695 files changed, 392062 insertions, 0 deletions

diff --git a/libs/tdlib/td/.clang-format b/libs/tdlib/td/.clang-format
new file mode 100644
index 0000000000..e169061bab
--- /dev/null
+++ b/libs/tdlib/td/.clang-format
@@ -0,0 +1,98 @@
+---
+Language:        Cpp
+# BasedOnStyle:  Google
+AccessModifierOffset: -1
+AlignAfterOpenBracket: Align
+AlignConsecutiveAssignments: false
+AlignConsecutiveDeclarations: false
+AlignEscapedNewlines: Left
+AlignOperands:   true
+AlignTrailingComments: true
+AllowAllParametersOfDeclarationOnNextLine: true
+AllowShortBlocksOnASingleLine: false
+AllowShortCaseLabelsOnASingleLine: false
+AllowShortFunctionsOnASingleLine: None # All
+AllowShortIfStatementsOnASingleLine: false # true
+AllowShortLoopsOnASingleLine: false # true
+AlwaysBreakAfterDefinitionReturnType: None
+AlwaysBreakAfterReturnType: None
+AlwaysBreakBeforeMultilineStrings: true
+AlwaysBreakTemplateDeclarations: true
+BinPackArguments: true
+BinPackParameters: true
+BraceWrapping:
+  AfterClass:      false
+  AfterControlStatement: false
+  AfterEnum:       false
+  AfterFunction:   false
+  AfterNamespace:  false
+  AfterObjCDeclaration: false
+  AfterStruct:     false
+  AfterUnion:      false
+  AfterExternBlock: false
+  BeforeCatch:     false
+  BeforeElse:      false
+  IndentBraces:    false
+  SplitEmptyFunction: true
+  SplitEmptyRecord: true
+  SplitEmptyNamespace: true
+BreakBeforeBinaryOperators: None
+BreakBeforeBraces: Attach
+BreakBeforeInheritanceComma: true # false
+BreakBeforeTernaryOperators: true
+BreakConstructorInitializersBeforeComma: true # false
+BreakConstructorInitializers: BeforeComma # BeforeColon
+# BreakAfterJavaFieldAnnotations: false
+BreakStringLiterals: true
+ColumnLimit:     120 # 80
+CommentPragmas:  '^ IWYU pragma:'
+CompactNamespaces: false
+ConstructorInitializerAllOnOneLineOrOnePerLine: true
+ConstructorInitializerIndentWidth: 4
+ContinuationIndentWidth: 4
+Cpp11BracedListStyle: true
+DerivePointerAlignment: true
+DisableFormat:   false
+ExperimentalAutoDetectBinPacking: false
+FixNamespaceComments: true
+# ForEachMacros: [ foreach, Q_FOREACH, BOOST_FOREACH ]
+IndentCaseLabels: true
+IndentPPDirectives: None
+IndentWidth:     2
+IndentWrappedFunctionNames: false
+# JavaScriptQuotes: Leave
+# JavaScriptWrapImports: true
+KeepEmptyLinesAtTheStartOfBlocks: false
+MacroBlockBegin: ''
+MacroBlockEnd:   ''
+MaxEmptyLinesToKeep: 1
+NamespaceIndentation: None
+# ObjCBlockIndentWidth: 2
+# ObjCSpaceAfterProperty: false
+# ObjCSpaceBeforeProtocolList: false
+PenaltyBreakAssignment: 2
+PenaltyBreakBeforeFirstCallParameter: 1
+PenaltyBreakComment: 300
+PenaltyBreakFirstLessLess: 120
+PenaltyBreakString: 1000
+PenaltyExcessCharacter: 1000000
+PenaltyReturnTypeOnItsOwnLine: 200
+PointerAlignment: Left
+ReflowComments:  false # true
+SortIncludes: false # disabled, because we need case insensitive sort
+SortUsingDeclarations: false # true
+SpaceAfterCStyleCast: false
+SpaceAfterTemplateKeyword: true
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeParens: ControlStatements
+SpaceInEmptyParentheses: false
+SpacesBeforeTrailingComments: 2
+SpacesInAngles:  false
+SpacesInContainerLiterals: true
+SpacesInCStyleCastParentheses: false
+SpacesInParentheses: false
+SpacesInSquareBrackets: false
+Standard:        Auto
+TabWidth:        100 # 8
+UseTab:          Never
+...
diff --git a/libs/tdlib/td/.gitattributes b/libs/tdlib/td/.gitattributes
new file mode 100644
index 0000000000..ecb5de5494
--- /dev/null
+++ b/libs/tdlib/td/.gitattributes
@@ -0,0 +1,36 @@
+* text=auto
+
+*.cpp text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.hpp text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.h text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.c text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.tl text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.txt text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.sh text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent eol=lf
+*.php text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.ps1 text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent eol=crlf
+*.yml text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.py text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.cmake text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.md text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+
+*.java text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.py text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.swift text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.cs text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.xaml text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.appxmanifest text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.json text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.csproj text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.sln text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.xml text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.rb text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.lock text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+*.go text whitespace=blank-at-eol,space-before-tab,blank-at-eof,tab-in-indent
+
+sqlite/sqlite/* linguist-vendored
+
+*.tlo binary
+
+*.pfx binary
+*.png binary
diff --git a/libs/tdlib/td/.gitignore b/libs/tdlib/td/.gitignore
new file mode 100644
index 0000000000..4b29dd985e
--- /dev/null
+++ b/libs/tdlib/td/.gitignore
@@ -0,0 +1,8 @@
+**/*build*/
+**/.*.swp
+**/.DS_Store
+**/auto/
+auto/
+db_backup
+*.pyc
+docs/
diff --git a/libs/tdlib/td/.travis.yml b/libs/tdlib/td/.travis.yml
new file mode 100644
index 0000000000..91e22933e9
--- /dev/null
+++ b/libs/tdlib/td/.travis.yml
@@ -0,0 +1,60 @@
+sudo: false
+dist: trusty
+
+addons_shortcuts:
+  addons_clang38: &clang38
+    apt:
+      sources:  [ 'ubuntu-toolchain-r-test', 'llvm-toolchain-precise-3.8' ]
+      packages: [ 'g++-5', 'clang-3.8','libc++-dev', 'libc++abi-dev', 'gperf']
+  addons_gcc5: &gcc5
+    apt:
+      sources:  [ 'ubuntu-toolchain-r-test']
+      packages: [ 'gcc-5','g++-5', 'gperf']
+
+branches:
+  only:
+  - travis
+
+language: cpp
+
+matrix:
+  include:
+    - os: linux
+      env: _CXX=g++-5 _CC=gcc-5 JOBS=1
+      addons: *gcc5
+    - os: linux
+      env: _CXX=clang++-3.8 _CC=clang-3.8 JOBS=4
+      addons: *clang38
+    - os: osx
+      env: JOBS=4
+      compiler: clang
+
+before_install:
+  #- sudo apt-get -qq update
+  #- sudo apt-get install -y libxml2-dev
+
+addons:
+  apt:
+    packages:
+      - gperf
+
+
+install:
+  # /usr/bin/gcc is 4.6 always, but gcc-X.Y is available.
+  - if [ "$TRAVIS_OS_NAME" = "osx" ]; then
+      export OPENSSL_ROOT_DIR=/usr/local/opt/openssl/;
+      brew link --force readline;
+      ulimit -n 1000;
+    fi
+  - false || [ -z "$_CXX" ] || export CXX=${_CXX}
+  - false || [ -z "$_CC" ] || export CC=${_CC}
+  - echo ${PATH}
+  - echo ${CXX}
+  - ${CXX} --version
+  - ${CXX} -v
+
+script:
+  - mkdir build
+  - cd build
+  - cmake .. && make -j${JOBS} VERBOSE=1
+  - ./test/run_all_tests --filter -client
diff --git a/libs/tdlib/td/.ycm_extra_conf.py b/libs/tdlib/td/.ycm_extra_conf.py
new file mode 100644
index 0000000000..dd6050fea6
--- /dev/null
+++ b/libs/tdlib/td/.ycm_extra_conf.py
@@ -0,0 +1,159 @@
+# This file is NOT licensed under the GPLv3, which is the license for the rest
+# of YouCompleteMe.
+#
+# Here's the license text for this file:
+#
+# This is free and unencumbered software released into the public domain.
+#
+# Anyone is free to copy, modify, publish, use, compile, sell, or
+# distribute this software, either in source code form or as a compiled
+# binary, for any purpose, commercial or non-commercial, and by any
+# means.
+#
+# In jurisdictions that recognize copyright laws, the author or authors
+# of this software dedicate any and all copyright interest in the
+# software to the public domain. We make this dedication for the benefit
+# of the public at large and to the detriment of our heirs and
+# successors. We intend this dedication to be an overt act of
+# relinquishment in perpetuity of all present and future rights to this
+# software under copyright law.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+# IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+# OTHER DEALINGS IN THE SOFTWARE.
+#
+# For more information, please refer to <http://unlicense.org/>
+
+import os
+import ycm_core
+
+# These are the compilation flags that will be used in case there's no
+# compilation database set (by default, one is not set).
+# CHANGE THIS LIST OF FLAGS. YES, THIS IS THE DROID YOU HAVE BEEN LOOKING FOR.
+flags = [
+"-stdlib=libc++",
+"-Wall",
+"-Wextra",
+"-Wno-unused-parameter",
+"-Wno-deprecated-declarations",
+"-std=c++14",
+"-x",
+"c++",
+"-I",
+".",
+"-I", "tdutils",
+"-I", "tdutils/generate",
+"-I", "tdactor",
+"-I", "tddb",
+"-I", "tdnet",
+"-I", "tdtl",
+"-I", "td/generate",
+"-I", "td/generate/auto",
+"-I", "td",
+"-isystem",
+"/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1",
+"-isystem",
+"/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/7.3.0/include",
+"-isystem",
+"/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include"
+]
+
+
+# Set this to the absolute path to the folder (NOT the file!) containing the
+# compile_commands.json file to use that instead of 'flags'. See here for
+# more details: http://clang.llvm.org/docs/JSONCompilationDatabase.html
+#
+# You can get CMake to generate this file for you by adding:
+#   set( CMAKE_EXPORT_COMPILE_COMMANDS 1 )
+# to your CMakeLists.txt file.
+#
+# Most projects will NOT need to set this to anything; you can just change the
+# 'flags' list of compilation flags. Notice that YCM itself uses that approach.
+compilation_database_folder = 'build'
+
+if os.path.exists( compilation_database_folder ):
+  database = ycm_core.CompilationDatabase( compilation_database_folder )
+else:
+  database = None
+
+SOURCE_EXTENSIONS = [ '.cpp', '.cxx', '.cc', '.c', '.m', '.mm' ]
+
+def DirectoryOfThisScript():
+  return os.path.dirname( os.path.abspath( __file__ ) )
+
+
+def MakeRelativePathsInFlagsAbsolute( flags, working_directory ):
+  if not working_directory:
+    return list( flags )
+  new_flags = []
+  make_next_absolute = False
+  path_flags = [ '-isystem', '-I', '-iquote', '--sysroot=' ]
+  for flag in flags:
+    new_flag = flag
+
+    if make_next_absolute:
+      make_next_absolute = False
+      if not flag.startswith( '/' ):
+        new_flag = os.path.join( working_directory, flag )
+
+    for path_flag in path_flags:
+      if flag == path_flag:
+        make_next_absolute = True
+        break
+
+      if flag.startswith( path_flag ):
+        path = flag[ len( path_flag ): ]
+        new_flag = path_flag + os.path.join( working_directory, path )
+        break
+
+    if new_flag:
+      new_flags.append( new_flag )
+  return new_flags
+
+
+def IsHeaderFile( filename ):
+  extension = os.path.splitext( filename )[ 1 ]
+  return extension in [ '.h', '.hxx', '.hpp', '.hh' ]
+
+
+def GetCompilationInfoForFile( filename ):
+  # The compilation_commands.json file generated by CMake does not have entries
+  # for header files. So we do our best by asking the db for flags for a
+  # corresponding source file, if any. If one exists, the flags for that file
+  # should be good enough.
+  if IsHeaderFile( filename ):
+    basename = os.path.splitext( filename )[ 0 ]
+    for extension in SOURCE_EXTENSIONS:
+      replacement_file = basename + extension
+      if os.path.exists( replacement_file ):
+        compilation_info = database.GetCompilationInfoForFile(
+          replacement_file )
+        if compilation_info.compiler_flags_:
+          return compilation_info
+    return None
+  return database.GetCompilationInfoForFile( filename )
+
+
+def FlagsForFile( filename, **kwargs ):
+  if database:
+    # Bear in mind that compilation_info.compiler_flags_ does NOT return a
+    # python list, but a "list-like" StringVec object
+    compilation_info = GetCompilationInfoForFile( filename )
+    if not compilation_info:
+      return None
+
+    final_flags = MakeRelativePathsInFlagsAbsolute(
+      compilation_info.compiler_flags_,
+      compilation_info.compiler_working_dir_ )
+  else:
+    relative_to = DirectoryOfThisScript()
+    final_flags = MakeRelativePathsInFlagsAbsolute( flags, relative_to )
+
+  return {
+    'flags': final_flags,
+    'do_cache': True
+  }
diff --git a/libs/tdlib/td/CHANGELOG.md b/libs/tdlib/td/CHANGELOG.md
new file mode 100644
index 0000000000..77a14246e2
--- /dev/null
+++ b/libs/tdlib/td/CHANGELOG.md
@@ -0,0 +1,89 @@
+Changes in 1.2.0:
+
+* Added support for native .NET bindings through `C++/CLI` and `C++/CX`.
+  See [using in .NET projects](README.md#using-dotnet) for more details.
+* Added a C# example. See [README](example/csharp/README.md) for build and usage instructions.
+* Added a build and usage example of TDLib SDK for Universal Windows Platform. See [README](example/uwp/README.md)
+  for detailed build and usage instructions. Also see [Unigram](https://github.com/UnigramDev/Unigram), which is
+  a full-featured client rewritten from scratch using TDLib SDK for Universal Windows Platform in less than 2 months.
+* Added a Swift example. See [README](example/swift/README.md) for build and usage instructions.
+* Added an example of building TDLib for iOS, watchOS, tvOS, and also macOS. See [README](example/ios/README.md) for
+  detailed build instructions.
+* Added README to [C++](example/cpp/README.md) and [python](example/python/README.md) examples.
+* Link Time Optimization is disabled by default. Use `-DTD_ENABLE_LTO=ON` CMake option and CMake >= 3.9 to enable it.
+* `updateNotificationSettings` is now automatically sent when the mute time expires for a chat.
+* Added automatic sending of a corresponding `chatAction` when a file is being uploaded.
+* `updateUserChatAction` with `chatActionCancel` is now automatically sent when the timeout expires for an action.
+* Authorization states `authorizationStateWaitCode` and `authorizationStateWaitPassword` are now saved between
+  library restarts for 5 minutes.
+* Added new message content type `messageWebsiteConnected`.
+* Added new text entity types `textEntityTypeCashtag` and `textEntityTypePhoneNumber`.
+* Added new update `updateUnreadMessageCount`, enabled when message database is used.
+* Method `joinChatByInviteLink` now returns the joined `Chat`.
+* Method `getWebPagePreview` now accepts `formattedText` instead of plain `string`.
+* Added field `phone_number` to `authenticationCodeInfo`, which contains a phone number that is being authenticated.
+* Added field `is_secret` to `messageAnimation`, `messagePhoto`, `messageVideo` and `messageVideoNote` classes,
+  which denotes whether the thumbnail for the content must be blurred and the content must be shown only while tapped.
+* Added field `expires_in` to `messageLocation` for live locations.
+* Added flag `can_be_reported` to `chat` class.
+* Added flag `supports_streaming` to classes `video` and `inputMessageVideo`.
+* Added parameter `message_ids` to `reportChat`, which can be used to report specific messages.
+* Added method `checkChatUsername` for checking whether a username can be set for a chat.
+* Added method `getRepliedMessage`, which returns a message that is replied by a given message.
+* Added method `getChatPinnedMessage`, which returns the pinned message from a chat.
+* Added method `searchStickers` to search by emoji for popular stickers suggested by the server.
+* Added method `searchStickerSets` to search by title and name for popular sticker sets suggested by the server.
+* Added method `searchInstalledStickerSets` to search by title and name for installed sticker sets.
+* Added methods for handling connected websites: `getConnectedWebsites`, `disconnectWebsite` and
+  `disconnectAllWebsites`.
+* Added method `getCountryCode`, which uses current user IP to identify their country.
+* Added option `t_me_url`.
+* Fixed `BlackBerry` spelling in `deviceTokenBlackBerryPush`.
+* Fixed return type of `getChatMessageByDate` method, which is `Message` and not `Messages`.
+* Ensured that updateOption("my_id") comes before `updateAuthorizationState` with `authorizationStateReady`.
+* Numerous optimizations and bug fixes.
+
+-----------------------------------------------------------------------------------------------------------------------
+
+Changes in 1.1.1:
+* Fixed C JSON bindings compilation error.
+* Fixed locale-dependent JSON generation.
+
+-----------------------------------------------------------------------------------------------------------------------
+
+Changes in 1.1.0:
+
+* Methods `td::Log::set_file_path` and `td_set_log_file_path` now return whether they succeeded.
+* Added methods `td::Log::set_max_file_size` and `td_set_log_max_file_size` for restricting maximum TDLib log size.
+* Added methods `td::Log::set_fatal_error_callback` and `td_set_log_fatal_error_callback` for providing callbacks
+  on fatal errors.
+* JNI-bindings are now package-agnostic. Use CMake option `TD_ENABLE_JNI` to enable JNI-bindings.
+* Added a Java example. See [README](example/java/README.md) for build and usage instructions.
+* Added support for text entities in media captions.
+  - Added new type `formattedText` containing a text with entities.
+  - Replaced all string fields `caption` with fields of type `formattedText`.
+  - Replaced fields `text` and `entities` with the field `text` of type `formattedText` in class `messageText`.
+  - Replaced fields `text` and `entities` with the field `text` of type `formattedText` in class `inputMessageText`.
+  - Replaced fields `text` and `text_entities` with the field `text` of type `formattedText` in class `game`.
+  - Removed field `parse_mode` from class `inputMessageText`.
+  - Added synchronous method `parseTextEntities`.
+* updateNewMessage is now sent for all sent messages.
+* updateChatLastMessage is now sent when any field of the last message in a chat changes.
+* Reworked the `registerDevice` method:
+  - Added parameter `other_user_ids` to method `registerDevice` to support multiple accounts.
+  - It is now possible to specify tokens for VoIP pushes, WNS, web Push API, Tizen Push Service as `DeviceToken`.
+  - Added support for Apple Push Notification Service inside App Sandbox.
+* Added method `searchChatsOnServer` analogous to `searchChats`, but using server search.
+* Results from the `searchChatsOnServer` method are now excluded from `searchPublicChats` results,
+  so `searchChatsOnServer` (along with `searchContacts`) should be called whenever `searchPublicChats` is called
+  to ensure that no results were omitted.
+* Added parameter `as_album` to method `getPublicMessageLink` to enable getting public links for media albums.
+* Added field `html` to class `publicMessageLink`, containing HTML-code for message/message album embedding.
+* Added parameter `only_if_pending` to method `cancelDownloadFile` to allow keeping already started downloads.
+* Methods `createPrivateChat`, `createBasciGroupChat`, `createSupergroupChat` and `createSecretChat`
+  can now be called without a prior call to `getUser`/`getBasicGroup`/`getSupergorup`/`getSecretChat`.
+* Added parameter `force` to methods `createPrivateChat`, `createBasciGroupChat` and `createSupergroupChat` to allow
+  creating a chat without network requests.
+* Numerous optimizations and bug fixes.
+
+-----------------------------------------------------------------------------------------------------------------------
diff --git a/libs/tdlib/td/CMake/AddCXXCompilerFlag.cmake b/libs/tdlib/td/CMake/AddCXXCompilerFlag.cmake
new file mode 100644
index 0000000000..b57fa4dd98
--- /dev/null
+++ b/libs/tdlib/td/CMake/AddCXXCompilerFlag.cmake
@@ -0,0 +1,74 @@
+# - Adds a compiler flag if it is supported by the compiler
+#
+# This function checks that the supplied compiler flag is supported and then
+# adds it to the corresponding compiler flags
+#
+#  add_cxx_compiler_flag(<FLAG> [<VARIANT>])
+#
+# - Example
+#
+# include(AddCXXCompilerFlag)
+# add_cxx_compiler_flag(-Wall)
+# add_cxx_compiler_flag(-no-strict-aliasing RELEASE)
+# Requires CMake 2.6+
+
+if(__add_cxx_compiler_flag)
+  return()
+endif()
+set(__add_cxx_compiler_flag INCLUDED)
+
+include(CheckCXXCompilerFlag)
+
+function(mangle_compiler_flag FLAG OUTPUT)
+  string(TOUPPER "HAVE_CXX_FLAG_${FLAG}" SANITIZED_FLAG)
+  string(REPLACE "+" "X" SANITIZED_FLAG ${SANITIZED_FLAG})
+  string(REGEX REPLACE "[^A-Za-z_0-9]" "_" SANITIZED_FLAG ${SANITIZED_FLAG})
+  string(REGEX REPLACE "_+" "_" SANITIZED_FLAG ${SANITIZED_FLAG})
+  set(${OUTPUT} "${SANITIZED_FLAG}" PARENT_SCOPE)
+endfunction(mangle_compiler_flag)
+
+function(add_cxx_compiler_flag FLAG)
+  string(REPLACE "-Wno-" "-W" MAIN_FLAG ${FLAG})
+  mangle_compiler_flag("${MAIN_FLAG}" MANGLED_FLAG)
+  if (DEFINED CMAKE_REQUIRED_FLAGS)
+    set(OLD_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
+    set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} ${FLAG}")
+  else()
+    set(CMAKE_REQUIRED_FLAGS "${FLAG}")
+  endif()
+  check_cxx_compiler_flag("${MAIN_FLAG}" ${MANGLED_FLAG})
+  if (DEFINED OLD_CMAKE_REQUIRED_FLAGS)
+    set(CMAKE_REQUIRED_FLAGS "${OLD_CMAKE_REQUIRED_FLAGS}")
+  else()
+    unset(CMAKE_REQUIRED_FLAGS)
+  endif()
+  if(${MANGLED_FLAG})
+    set(VARIANT ${ARGV1})
+    if(ARGV1)
+      string(TOUPPER "_${VARIANT}" VARIANT)
+    endif()
+    set(CMAKE_CXX_FLAGS${VARIANT} "${CMAKE_CXX_FLAGS${VARIANT}} ${FLAG}" PARENT_SCOPE)
+  endif()
+endfunction()
+
+function(add_required_cxx_compiler_flag FLAG)
+  string(REPLACE "-Wno-" "-W" MAIN_FLAG ${FLAG})
+  mangle_compiler_flag("${MAIN_FLAG}" MANGLED_FLAG)
+  set(OLD_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
+  set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} ${FLAG}")
+  check_cxx_compiler_flag("${MAIN_FLAG}" ${MANGLED_FLAG})
+  set(CMAKE_REQUIRED_FLAGS "${OLD_CMAKE_REQUIRED_FLAGS}")
+  if (${MANGLED_FLAG})
+    set(VARIANT ${ARGV1})
+    if (ARGV1)
+      string(TOUPPER "_${VARIANT}" VARIANT)
+    endif()
+    set(CMAKE_CXX_FLAGS${VARIANT} "${CMAKE_CXX_FLAGS${VARIANT}} ${FLAG}" PARENT_SCOPE)
+    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${FLAG}" PARENT_SCOPE)
+    set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${FLAG}" PARENT_SCOPE)
+    set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} ${FLAG}" PARENT_SCOPE)
+    set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} ${FLAG}" PARENT_SCOPE)
+  else()
+    message(FATAL_ERROR "Required flag '${FLAG}' is not supported by the compiler")
+  endif()
+endfunction()
diff --git a/libs/tdlib/td/CMake/FindReadline.cmake b/libs/tdlib/td/CMake/FindReadline.cmake
new file mode 100644
index 0000000000..dab24bb19f
--- /dev/null
+++ b/libs/tdlib/td/CMake/FindReadline.cmake
@@ -0,0 +1,25 @@
+if (APPLE)
+  find_path(READLINE_INCLUDE_DIR readline/readline.h /usr/local/opt/readline/include /opt/local/include /opt/include /usr/local/include /usr/include NO_DEFAULT_PATH)
+endif()
+find_path(READLINE_INCLUDE_DIR readline/readline.h)
+
+if (APPLE)
+  find_library(READLINE_LIBRARY readline /usr/local/opt/readline/lib /opt/local/lib /opt/lib /usr/local/lib /usr/lib NO_DEFAULT_PATH)
+endif()
+find_library(READLINE_LIBRARY readline)
+
+if (READLINE_INCLUDE_DIR AND READLINE_LIBRARY AND NOT GNU_READLINE_FOUND)
+  set(CMAKE_REQUIRED_INCLUDES "${READLINE_INCLUDE_DIR}")
+  set(CMAKE_REQUIRED_LIBRARIES "${READLINE_LIBRARY}")
+  include(CheckCXXSourceCompiles)
+  unset(GNU_READLINE_FOUND CACHE)
+  CHECK_CXX_SOURCE_COMPILES("#include <stdio.h>\n#include <readline/readline.h>\nint main() { rl_replace_line(\"\", 0); }" GNU_READLINE_FOUND)
+  if (NOT GNU_READLINE_FOUND)
+    unset(READLINE_INCLUDE_DIR CACHE)
+    unset(READLINE_LIBRARY CACHE)
+  endif()
+endif()
+
+include(FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(Readline DEFAULT_MSG READLINE_INCLUDE_DIR READLINE_LIBRARY)
+mark_as_advanced(READLINE_INCLUDE_DIR READLINE_LIBRARY)
diff --git a/libs/tdlib/td/CMake/iOS.cmake b/libs/tdlib/td/CMake/iOS.cmake
new file mode 100644
index 0000000000..9b395a0764
--- /dev/null
+++ b/libs/tdlib/td/CMake/iOS.cmake
@@ -0,0 +1,250 @@
+# This file is based off of the Platform/Darwin.cmake and Platform/UnixPaths.cmake
+# files which are included with CMake 2.8.4
+# It has been altered for iOS development
+
+# Options:
+#
+# IOS_PLATFORM = OS (default) or SIMULATOR
+#   This decides if SDKS will be selected from the iPhoneOS.platform or iPhoneSimulator.platform folders
+#   OS - the default, used to build for iPhone and iPad physical devices, which have an arm arch.
+#   SIMULATOR - used to build for the Simulator platforms, which have an x86 arch.
+#
+# CMAKE_IOS_DEVELOPER_ROOT = automatic(default) or /path/to/platform/Developer folder
+#   By default this location is automatcially chosen based on the IOS_PLATFORM value above.
+#   If set manually, it will override the default location and force the user of a particular Developer Platform
+#
+# CMAKE_IOS_SDK_ROOT = automatic(default) or /path/to/platform/Developer/SDKs/SDK folder
+#   By default this location is automatcially chosen based on the CMAKE_IOS_DEVELOPER_ROOT value.
+#   In this case it will always be the most up-to-date SDK found in the CMAKE_IOS_DEVELOPER_ROOT path.
+#   If set manually, this will force the use of a specific SDK version
+
+# Macros:
+#
+# set_xcode_property (TARGET XCODE_PROPERTY XCODE_VALUE)
+#  A convenience macro for setting xcode specific properties on targets
+#  example: set_xcode_property (myioslib IPHONEOS_DEPLOYMENT_TARGET "3.1")
+#
+# find_host_package (PROGRAM ARGS)
+#  A macro used to find executable programs on the host system, not within the iOS environment.
+#  Thanks to the android-cmake project for providing the command
+
+# Standard settings
+set (CMAKE_SYSTEM_NAME Darwin)
+set (CMAKE_SYSTEM_VERSION 1)
+set (UNIX True)
+set (APPLE True)
+set (IOS True)
+
+# Required as of cmake 2.8.10
+set (CMAKE_OSX_DEPLOYMENT_TARGET "" CACHE STRING "Force unset of the deployment target for iOS" FORCE)
+
+# Determine the cmake host system version so we know where to find the iOS SDKs
+find_program (CMAKE_UNAME uname /bin /usr/bin /usr/local/bin)
+if (CMAKE_UNAME)
+    exec_program(uname ARGS -r OUTPUT_VARIABLE CMAKE_HOST_SYSTEM_VERSION)
+    string (REGEX REPLACE "^([0-9]+)\\.([0-9]+).*$" "\\1" DARWIN_MAJOR_VERSION "${CMAKE_HOST_SYSTEM_VERSION}")
+endif (CMAKE_UNAME)
+
+# Force the compilers to gcc for iOS
+set (CMAKE_C_COMPILER /usr/bin/gcc)
+set (CMAKE_CXX_COMPILER /usr/bin/g++)
+set(CMAKE_AR ar CACHE FILEPATH "" FORCE)
+set(CMAKE_RANLIB ranlib CACHE FILEPATH "" FORCE)
+set(PKG_CONFIG_EXECUTABLE pkg-config CACHE FILEPATH "" FORCE)
+
+# Setup iOS platform unless specified manually with IOS_PLATFORM
+if (NOT DEFINED IOS_PLATFORM)
+    set (IOS_PLATFORM "OS")
+endif (NOT DEFINED IOS_PLATFORM)
+set (IOS_PLATFORM ${IOS_PLATFORM} CACHE STRING "Type of iOS Platform")
+
+# Check the platform selection and setup for developer root
+if (${IOS_PLATFORM} STREQUAL "OS")
+    set (IOS_PLATFORM_LOCATION "iPhoneOS.platform")
+    set (XCODE_IOS_PLATFORM iphoneos)
+
+    # This causes the installers to properly locate the output libraries
+    set (CMAKE_XCODE_EFFECTIVE_PLATFORMS "-iphoneos")
+
+    set (APPLE_IOS True)
+elseif (${IOS_PLATFORM} STREQUAL "SIMULATOR")
+    set (SIMULATOR_FLAG true)
+    set (IOS_PLATFORM_LOCATION "iPhoneSimulator.platform")
+    set (XCODE_IOS_PLATFORM iphonesimulator)
+
+    # This causes the installers to properly locate the output libraries
+    set (CMAKE_XCODE_EFFECTIVE_PLATFORMS "-iphonesimulator")
+
+    set (APPLE_IOS True)
+elseif (${IOS_PLATFORM} STREQUAL "WATCHOS")
+    set (IOS_PLATFORM_LOCATION "WatchOS.platform")
+    set (XCODE_IOS_PLATFORM watchos)
+
+    # This causes the installers to properly locate the output libraries
+    set (CMAKE_XCODE_EFFECTIVE_PLATFORMS "-watchos")
+
+    set (APPLE_WATCH True)
+elseif (${IOS_PLATFORM} STREQUAL "WATCHSIMULATOR")
+    set (SIMULATOR_FLAG true)
+    set (IOS_PLATFORM_LOCATION "WatchSimulator.platform")
+    set (XCODE_IOS_PLATFORM watchsimulator)
+
+    # This causes the installers to properly locate the output libraries
+    set (CMAKE_XCODE_EFFECTIVE_PLATFORMS "-watchsimulator")
+
+    set (APPLE_WATCH True)
+elseif (${IOS_PLATFORM} STREQUAL "TVOS")
+    set (IOS_PLATFORM_LOCATION "AppleTvOS.platform")
+    set (XCODE_IOS_PLATFORM tvos)
+
+    # This causes the installers to properly locate the output libraries
+    set (CMAKE_XCODE_EFFECTIVE_PLATFORMS "-appletvos")
+
+    set (APPLE_TV True)
+elseif (${IOS_PLATFORM} STREQUAL "TVSIMULATOR")
+    set (SIMULATOR_FLAG true)
+    set (IOS_PLATFORM_LOCATION "AppleTvSimulator.platform")
+    set (XCODE_IOS_PLATFORM tvsimulator)
+
+    # This causes the installers to properly locate the output libraries
+    set (CMAKE_XCODE_EFFECTIVE_PLATFORMS "-tvsimulator")
+
+    set (APPLE_TV True)
+else (${IOS_PLATFORM} STREQUAL "OS")
+    message (FATAL_ERROR "Unsupported IOS_PLATFORM value selected. Please choose OS, SIMULATOR, or WATCHOS.")
+endif ()
+
+# All iOS/Darwin specific settings - some may be redundant
+set (CMAKE_SHARED_LIBRARY_PREFIX "lib")
+set (CMAKE_SHARED_LIBRARY_SUFFIX ".dylib")
+set (CMAKE_SHARED_MODULE_PREFIX "lib")
+set (CMAKE_SHARED_MODULE_SUFFIX ".so")
+set (CMAKE_MODULE_EXISTS 1)
+set (CMAKE_DL_LIBS "")
+
+set (CMAKE_C_OSX_COMPATIBILITY_VERSION_FLAG "-compatibility_version ")
+set (CMAKE_C_OSX_CURRENT_VERSION_FLAG "-current_version ")
+set (CMAKE_CXX_OSX_COMPATIBILITY_VERSION_FLAG "${CMAKE_C_OSX_COMPATIBILITY_VERSION_FLAG}")
+set (CMAKE_CXX_OSX_CURRENT_VERSION_FLAG "${CMAKE_C_OSX_CURRENT_VERSION_FLAG}")
+
+if (IOS_DEPLOYMENT_TARGET)
+    set (XCODE_IOS_PLATFORM_VERSION_FLAGS "-m${XCODE_IOS_PLATFORM}-version-min=${IOS_DEPLOYMENT_TARGET}")
+endif()
+
+set (CMAKE_SHARED_LINKER_FLAGS_INIT "-fapplication-extension")
+if (NOT SIMULATOR_FLAG)
+    set (BITCODE "-fembed-bitcode")
+endif()
+set (CMAKE_C_FLAGS_INIT "${XCODE_IOS_PLATFORM_VERSION_FLAGS} ${BITCODE}")
+# Hidden visibilty is required for cxx on iOS
+set (CMAKE_CXX_FLAGS_INIT "${XCODE_IOS_PLATFORM_VERSION_FLAGS} ${BITCODE} -fvisibility-inlines-hidden")
+
+set (CMAKE_C_LINK_FLAGS   "${XCODE_IOS_PLATFORM_VERSION_FLAGS} -fapplication-extension -Wl,-search_paths_first ${CMAKE_C_LINK_FLAGS}")
+set (CMAKE_CXX_LINK_FLAGS "${XCODE_IOS_PLATFORM_VERSION_FLAGS} -fapplication-extension -Wl,-search_paths_first ${CMAKE_CXX_LINK_FLAGS}")
+
+set (CMAKE_PLATFORM_HAS_INSTALLNAME 1)
+set (CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS "-dynamiclib -headerpad_max_install_names")
+set (CMAKE_SHARED_MODULE_CREATE_C_FLAGS "-bundle -headerpad_max_install_names")
+set (CMAKE_SHARED_MODULE_LOADER_C_FLAG "-Wl,-bundle_loader,")
+set (CMAKE_SHARED_MODULE_LOADER_CXX_FLAG "-Wl,-bundle_loader,")
+set (CMAKE_FIND_LIBRARY_SUFFIXES ".dylib" ".so" ".a")
+
+# hack: if a new cmake (which uses CMAKE_INSTALL_NAME_TOOL) runs on an old build tree
+# (where install_name_tool was hardcoded) and where CMAKE_INSTALL_NAME_TOOL isn't in the cache
+# and still cmake didn't fail in CMakeFindBinUtils.cmake (because it isn't rerun)
+# hardcode CMAKE_INSTALL_NAME_TOOL here to install_name_tool, so it behaves as it did before, Alex
+if (NOT DEFINED CMAKE_INSTALL_NAME_TOOL)
+    find_program(CMAKE_INSTALL_NAME_TOOL install_name_tool)
+endif (NOT DEFINED CMAKE_INSTALL_NAME_TOOL)
+
+# Setup iOS deployment target
+set (IOS_DEPLOYMENT_TARGET ${IOS_DEPLOYMENT_TARGET} CACHE STRING "Minimum iOS version")
+
+# Setup iOS developer location unless specified manually with CMAKE_IOS_DEVELOPER_ROOT
+# Note Xcode 4.3 changed the installation location, choose the most recent one available
+exec_program(/usr/bin/xcode-select ARGS -print-path OUTPUT_VARIABLE CMAKE_XCODE_DEVELOPER_DIR)
+set (XCODE_POST_43_ROOT "${CMAKE_XCODE_DEVELOPER_DIR}/Platforms/${IOS_PLATFORM_LOCATION}/Developer")
+set (XCODE_PRE_43_ROOT "/Developer/Platforms/${IOS_PLATFORM_LOCATION}/Developer")
+if (NOT DEFINED CMAKE_IOS_DEVELOPER_ROOT)
+    if (EXISTS ${XCODE_POST_43_ROOT})
+        set (CMAKE_IOS_DEVELOPER_ROOT ${XCODE_POST_43_ROOT})
+    elseif(EXISTS ${XCODE_PRE_43_ROOT})
+        set (CMAKE_IOS_DEVELOPER_ROOT ${XCODE_PRE_43_ROOT})
+    endif (EXISTS ${XCODE_POST_43_ROOT})
+endif (NOT DEFINED CMAKE_IOS_DEVELOPER_ROOT)
+set (CMAKE_IOS_DEVELOPER_ROOT ${CMAKE_IOS_DEVELOPER_ROOT} CACHE PATH "Location of iOS Platform")
+
+# Find and use the most recent iOS sdk unless specified manually with CMAKE_IOS_SDK_ROOT
+if (NOT DEFINED CMAKE_IOS_SDK_ROOT)
+    file (GLOB _CMAKE_IOS_SDKS "${CMAKE_IOS_DEVELOPER_ROOT}/SDKs/*")
+    if (_CMAKE_IOS_SDKS)
+        list (SORT _CMAKE_IOS_SDKS)
+        list (REVERSE _CMAKE_IOS_SDKS)
+        list (GET _CMAKE_IOS_SDKS 0 CMAKE_IOS_SDK_ROOT)
+    else (_CMAKE_IOS_SDKS)
+        message (FATAL_ERROR "No iOS SDK's found in default search path ${CMAKE_IOS_DEVELOPER_ROOT}. Manually set CMAKE_IOS_SDK_ROOT or install the iOS SDK.")
+    endif (_CMAKE_IOS_SDKS)
+    message (STATUS "Toolchain using default iOS SDK: ${CMAKE_IOS_SDK_ROOT}")
+endif (NOT DEFINED CMAKE_IOS_SDK_ROOT)
+set (CMAKE_IOS_SDK_ROOT ${CMAKE_IOS_SDK_ROOT} CACHE PATH "Location of the selected iOS SDK")
+
+# Set the sysroot default to the most recent SDK
+set (CMAKE_OSX_SYSROOT ${CMAKE_IOS_SDK_ROOT} CACHE PATH "Sysroot used for iOS support")
+
+# set the architecture for iOS
+if (IOS_PLATFORM STREQUAL "OS")
+    set (IOS_ARCH "armv7;armv7s;arm64")
+elseif (IOS_PLATFORM STREQUAL "SIMULATOR")
+    set (IOS_ARCH "i386;x86_64")
+elseif (IOS_PLATFORM STREQUAL "WATCHOS")
+    set (IOS_ARCH "armv7k")
+elseif (IOS_PLATFORM STREQUAL "WATCHSIMULATOR")
+    set (IOS_ARCH "i386")
+elseif (IOS_PLATFORM STREQUAL "TVOS")
+    set (IOS_ARCH "arm64")
+elseif (IOS_PLATFORM STREQUAL "TVSIMULATOR")
+    set (IOS_ARCH "x86_64")
+else()
+    message (WARNING "Unknown IOS_PLATFORM=<${IOS_PLATFORM}>")
+endif()
+message (STATUS ${IOS_ARCH})
+
+set (CMAKE_OSX_ARCHITECTURES ${IOS_ARCH} CACHE STRING "Build architecture for iOS")
+
+# Set the find root to the iOS developer roots and to user defined paths
+set (CMAKE_FIND_ROOT_PATH ${CMAKE_IOS_DEVELOPER_ROOT} ${CMAKE_IOS_SDK_ROOT} ${CMAKE_PREFIX_PATH} CACHE STRING "iOS find search path root")
+
+# default to searching for frameworks first
+set (CMAKE_FIND_FRAMEWORK FIRST)
+
+# set up the default search directories for frameworks
+set (CMAKE_SYSTEM_FRAMEWORK_PATH
+    ${CMAKE_IOS_SDK_ROOT}/System/Library/Frameworks
+    ${CMAKE_IOS_SDK_ROOT}/System/Library/PrivateFrameworks
+    ${CMAKE_IOS_SDK_ROOT}/Developer/Library/Frameworks
+)
+
+# only search the iOS sdks, not the remainder of the host filesystem
+set (CMAKE_FIND_ROOT_PATH_MODE_PROGRAM ONLY)
+set (CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set (CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+
+# This little macro lets you set any Xcode specific property
+macro (set_xcode_property TARGET XCODE_PROPERTY XCODE_VALUE)
+    set_property (TARGET ${TARGET} PROPERTY XCODE_ATTRIBUTE_${XCODE_PROPERTY} ${XCODE_VALUE})
+endmacro (set_xcode_property)
+
+# This macro lets you find executable programs on the host system
+macro (find_host_package)
+    set (CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+    set (CMAKE_FIND_ROOT_PATH_MODE_LIBRARY NEVER)
+    set (CMAKE_FIND_ROOT_PATH_MODE_INCLUDE NEVER)
+    set (IOS FALSE)
+
+    find_package(${ARGN})
+
+    set (IOS TRUE)
+    set (CMAKE_FIND_ROOT_PATH_MODE_PROGRAM ONLY)
+    set (CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+    set (CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+endmacro (find_host_package)
diff --git a/libs/tdlib/td/CMakeLists.txt b/libs/tdlib/td/CMakeLists.txt
new file mode 100644
index 0000000000..5e2a626021
--- /dev/null
+++ b/libs/tdlib/td/CMakeLists.txt
@@ -0,0 +1,792 @@
+cmake_minimum_required(VERSION 3.0.2 FATAL_ERROR)
+
+project(TDLib VERSION 1.2.0 LANGUAGES CXX C)
+
+# Prevent in-source build
+get_filename_component(TD_REAL_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}" REALPATH)
+get_filename_component(TD_REAL_BINARY_DIR "${CMAKE_CURRENT_BINARY_DIR}" REALPATH)
+
+if (TD_REAL_BINARY_DIR STREQUAL TD_REAL_SOURCE_DIR)
+  message("  Out-of-source build should be used to build TDLib.")
+  message("  You need to remove the files already created by CMake and")
+  message("  rerun CMake from a new directory:")
+  message("  rm -rf CMakeFiles CMakeCache.txt")
+  message("  mkdir build")
+  message("  cd build")
+  message("  cmake ..")
+  message(FATAL_ERROR "In-source build failed.")
+endif()
+
+option(TD_ENABLE_JNI "Use \"ON\" to enable JNI-compatible TDLib API.")
+option(TD_ENABLE_DOTNET "Use \"ON\" to enable generation of C++/CLI or C++/CX TDLib API bindings.")
+
+if (TD_ENABLE_DOTNET AND (CMAKE_VERSION VERSION_LESS "3.1.0"))
+  message(FATAL_ERROR "CMake 3.1.0 or higher is required. You are running version ${CMAKE_VERSION}.")
+endif()
+
+if (NOT DEFINED CMAKE_MODULE_PATH)
+  set(CMAKE_MODULE_PATH "")
+endif()
+set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/CMake" "${CMAKE_MODULE_PATH}")
+
+set(CMAKE_EXPORT_COMPILE_COMMANDS 1)
+
+set(CMAKE_POSITION_INDEPENDENT_CODE ON)
+
+enable_testing()
+
+if (POLICY CMP0069)
+  option(TD_ENABLE_LTO "Use \"ON\" to enable Link Time Optimization.")
+
+  if (TD_ENABLE_LTO)
+    cmake_policy(SET CMP0069 NEW)
+    include(CheckIPOSupported)
+    check_ipo_supported(RESULT IPO_SUPPORTED)
+    if (IPO_SUPPORTED)
+      # set_property(DIRECTORY PROPERTY INTERPROCEDURAL_OPTIMIZATION TRUE) do not work?
+      string(REPLACE ";" " " CXX_FLAGS_IPO "${CMAKE_CXX_COMPILE_OPTIONS_IPO}")
+      message(STATUS "Use link time optimization CXX options: ${CXX_FLAGS_IPO}")
+      set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} ${CXX_FLAGS_IPO}")
+
+      string(REPLACE ";" " " C_FLAGS_IPO "${CMAKE_C_COMPILE_OPTIONS_IPO}")
+      message(STATUS "Use link time optimization C options: ${C_FLAGS_IPO}")
+      set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} ${C_FLAGS_IPO}")
+
+      string(REPLACE ";" " " LINK_FLAGS_IPO "${CMAKE_CXX_LINK_OPTIONS_IPO}")
+      message(STATUS "Use link time optimization linker options: ${LINK_FLAGS_IPO}")
+      set(CMAKE_EXE_LINKER_FLAGS_RELEASE "${CMAKE_EXE_LINKER_FLAGS_RELEASE} ${LINK_FLAGS_IPO}")
+    endif()
+  endif()
+endif()
+
+# Configure CCache if available
+find_program(CCACHE_FOUND ccache)
+#set(CCACHE_FOUND 0)
+if (CCACHE_FOUND)
+  message(STATUS "Found ccache")
+  set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE ccache)
+  set_property(GLOBAL PROPERTY RULE_LAUNCH_LINK ccache)
+else()
+  message(STATUS "Could NOT find ccache")
+endif()
+
+set(MEMPROF "" CACHE STRING "Use one of \"ON\", \"FAST\" or \"SAFE\" to enable memory profiling. \
+Works under Mac OS and Linux when compiled using glibc. \
+In FAST mode stack is unwinded only using frame pointers, which may fail. \
+In SAFE mode stack is unwinded using backtrace function from execinfo.h, which may be very slow. \
+By default both methods are used to achieve maximum speed and accuracy")
+
+if (EMSCRIPTEN)
+  # use prebuilt zlib
+  set(ZLIB_FOUND 1)
+  set(ZLIB_LIBRARIES)
+  set(ZLIB_INCLUDE_DIR)
+
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Os -s ALLOW_MEMORY_GROWTH=1 -s USE_ZLIB=1 -s MODULARIZE=1 -s EXTRA_EXPORTED_RUNTIME_METHODS=\"['FS']\"")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Os -s ALLOW_MEMORY_GROWTH=1 -s USE_ZLIB=1 -s MODULARIZE=1 -s EXTRA_EXPORTED_RUNTIME_METHODS=\"['FS']\"")
+  set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -s DEMANGLE_SUPPORT=1 -s ASSERTIONS=1")
+  set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -s DEMANGLE_SUPPORT=1 -s ASSERTIONS=1")
+
+  if (ASMJS)
+    set(TD_EMSCRIPTEN td_asmjs)
+  else()
+    set(TD_EMSCRIPTEN td_wasm)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -s WASM=1")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -s WASM=1")
+  endif()
+endif()
+
+if (NOT OPENSSL_FOUND)
+  find_package(OpenSSL)
+endif()
+if (OPENSSL_FOUND)
+  message(STATUS "Found OpenSSL: ${OPENSSL_INCLUDE_DIR} ${OPENSSL_LIBRARIES}")
+endif()
+
+if (${CMAKE_CXX_COMPILER_ID} STREQUAL GNU)
+  set(GCC 1)
+elseif (${CMAKE_CXX_COMPILER_ID} MATCHES Clang)
+  set(CLANG 1)
+elseif (${CMAKE_CXX_COMPILER_ID} STREQUAL Intel)
+  set(INTEL 1)
+elseif (NOT MSVC)
+  message(FATAL_ERROR "Compiler isn't supported")
+endif()
+
+include(CheckCXXCompilerFlag)
+
+if (GCC OR CLANG OR INTEL)
+  if (WIN32 AND INTEL)
+    SET(STD14_FLAG /Qstd=c++14)
+  else()
+    SET(STD14_FLAG -std=c++14)
+  endif()
+  CHECK_CXX_COMPILER_FLAG(${STD14_FLAG} HAVE_STD14)
+  if (NOT HAVE_STD14)
+    string(REPLACE "c++14" "c++1y" STD14_FLAG "${STD14_FLAG}")
+    CHECK_CXX_COMPILER_FLAG(${STD14_FLAG} HAVE_STD1Y)
+    set(HAVE_STD14 ${HAVE_STD1Y})
+  endif()
+elseif (MSVC)
+  set(HAVE_STD14 MSVC_VERSION>=1900)
+endif()
+
+if (NOT HAVE_STD14)
+  message(FATAL_ERROR "No C++14 support in the compiler. Please upgrade the compiler.")
+endif()
+
+set(CMAKE_THREAD_PREFER_PTHREAD ON)
+set(THREADS_PREFER_PTHREAD_FLAG ON)
+find_package(Threads REQUIRED)
+
+if (THREADS_HAVE_PTHREAD_ARG)
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pthread")
+endif()
+
+if (MSVC)
+  if (CMAKE_CXX_FLAGS_DEBUG MATCHES "/RTC1")
+    string(REPLACE "/RTC1" " " CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG}")
+  endif()
+  add_definitions(-D_SCL_SECURE_NO_WARNINGS -D_CRT_SECURE_NO_WARNINGS)
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /GR- /W4 /wd4100 /wd4127 /wd4324 /wd4505 /wd4702")
+elseif (CLANG OR GCC)
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${STD14_FLAG} -fno-omit-frame-pointer -fno-exceptions -fno-rtti")
+  if (APPLE)
+    set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,-dead_strip,-x,-S")
+  else()
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -ffunction-sections -fdata-sections")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -ffunction-sections -fdata-sections")
+    set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,--gc-sections -Wl,--exclude-libs,ALL")
+  endif()
+
+  if (MEMPROF)
+    CHECK_CXX_COMPILER_FLAG(-no-pie CXX_NO_PIE_FLAG)
+    if (CXX_NO_PIE_FLAG)
+      set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -no-pie")
+    elseif (APPLE)
+      set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,-no_pie")
+    endif()
+  endif()
+elseif (INTEL)
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${STD14_FLAG}")
+endif()
+
+if (WIN32)
+  add_definitions(-DNTDDI_VERSION=0x06020000 -DWINVER=0x0602 -D_WIN32_WINNT=0x0602 -DNOMINMAX -DUNICODE -D_UNICODE)
+endif()
+if (CYGWIN)
+  add_definitions(-D_DEFAULT_SOURCE=1 -DFD_SETSIZE=4096)
+endif()
+
+if (NOT ANDROID) # _FILE_OFFSET_BITS is broken in ndk r15 and r15b and doesn't work prior to Android 7.0
+  add_definitions(-D_FILE_OFFSET_BITS=64)
+endif()
+
+include(AddCXXCompilerFlag)
+if (NOT MSVC)
+  add_cxx_compiler_flag("-Wall")
+  add_cxx_compiler_flag("-Wextra")
+  add_cxx_compiler_flag("-Wimplicit-fallthrough=2")
+  add_cxx_compiler_flag("-Wpointer-arith")
+  add_cxx_compiler_flag("-Wcast-qual")
+  add_cxx_compiler_flag("-Wsign-compare")
+  add_cxx_compiler_flag("-Wduplicated-branches")
+  add_cxx_compiler_flag("-Wduplicated-cond")
+  add_cxx_compiler_flag("-Walloc-zero")
+  add_cxx_compiler_flag("-Wlogical-op")
+  add_cxx_compiler_flag("-Wno-tautological-compare")
+  add_cxx_compiler_flag("-Wpointer-arith")
+  add_cxx_compiler_flag("-Wvla")
+  add_cxx_compiler_flag("-Wnon-virtual-dtor")
+  add_cxx_compiler_flag("-Wno-unused-parameter")
+  add_cxx_compiler_flag("-Wconversion")
+  add_cxx_compiler_flag("-Wno-sign-conversion")
+  add_cxx_compiler_flag("-Wc++14-compat-pedantic")
+  add_cxx_compiler_flag("-Qunused-arguments")
+  add_cxx_compiler_flag("-Wodr")
+  add_cxx_compiler_flag("-flto-odr-type-merging")
+
+#  add_cxx_compiler_flag("-Werror")
+
+#  add_cxx_compiler_flag("-Wcast-align")
+
+#std::int32_t <-> int and off_t <-> std::size_t/std::int64_t
+#  add_cxx_compiler_flag("-Wuseless-cast")
+
+#external headers like openssl
+#  add_cxx_compiler_flag("-Wzero-as-null-pointer-constant")
+endif()
+
+#set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -isystem /usr/include/c++/v1")
+#set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libc++")
+#set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=thread")
+#set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=address")
+#set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=undefined")
+#set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=leak")
+
+add_subdirectory(tdtl)
+
+add_subdirectory(tdutils)
+
+add_subdirectory(td/generate)
+
+if (NOT CMAKE_CROSSCOMPILING)
+  add_custom_target(prepare_cross_compiling DEPENDS tl_generate_common tdmime_auto tl_generate_json)
+  if (TD_ENABLE_DOTNET)
+    add_custom_target(remove_cpp_documentation
+      WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+      COMMAND remove_documentation ${TL_TD_AUTO} td/telegram/Client.h td/telegram/Log.h td/tl/TlObject.h
+      COMMENT "Remove C++ documentation from sources"
+      DEPENDS remove_documentation tl_generate_common generate_dotnet_api ${TL_TD_AUTO} td/telegram/Client.h td/telegram/Log.h td/tl/TlObject.h
+    )
+
+    add_dependencies(prepare_cross_compiling generate_dotnet_api remove_cpp_documentation)
+  endif()
+endif()
+
+if (NOT OPENSSL_FOUND)
+  message(WARNING "Not found OpenSSL: skip TDLib, tdactor, tdnet, tddb")
+  return()
+endif()
+
+if (NOT ZLIB_FOUND)
+  find_package(ZLIB)
+endif()
+if (NOT ZLIB_FOUND)
+  message(WARNING "Not found zlib: skip TDLib, tdactor, tdnet, tddb")
+  return()
+endif()
+
+add_subdirectory(tdactor)
+
+add_subdirectory(tdnet)
+
+add_subdirectory(sqlite)
+
+add_subdirectory(tddb)
+
+add_subdirectory(test)
+
+if (NOT CMAKE_CROSSCOMPILING)
+  add_subdirectory(benchmark)
+endif()
+
+
+get_directory_property(HAS_PARENT PARENT_DIRECTORY)
+if (HAS_PARENT)
+  set(TL_TD_AUTO_INCLUDES ${TL_TD_AUTO_INCLUDES} PARENT_SCOPE)
+  set(TL_TD_API_TLO ${TL_TD_API_TLO} PARENT_SCOPE)
+  set(TL_TD_JSON_AUTO ${TL_TD_JSON_AUTO} PARENT_SCOPE)
+  set(TD_TEST_SOURCE ${TD_TEST_SOURCE} PARENT_SCOPE)
+endif()
+
+
+#SOURCE SETS
+
+set_source_files_properties(${TL_TD_AUTO} PROPERTIES GENERATED TRUE)
+if (TD_ENABLE_JNI)
+  set(TL_JNI_OBJECT
+    td/tl/tl_jni_object.cpp
+    td/tl/tl_jni_object.h
+  )
+else()
+  set(TL_JNI_OBJECT)
+endif()
+
+set(TL_TD_SCHEME_SOURCE
+  ${TL_TD_AUTO}
+  ${TL_JNI_OBJECT}
+  td/tl/TlObject.h
+  td/tl/tl_object_parse.h
+  td/tl/tl_object_store.h
+)
+
+set_source_files_properties(${TL_TD_JSON_AUTO} PROPERTIES GENERATED TRUE)
+set(TL_TD_JSON
+  ${TL_TD_JSON_AUTO}
+  td/tl/tl_json.h
+)
+
+set_source_files_properties(${TL_C_AUTO} PROPERTIES GENERATED TRUE)
+set(TL_C_SCHEME_SOURCE
+  ${TL_C_AUTO}
+)
+
+set_source_files_properties(${TL_DOTNET_AUTO} PROPERTIES GENERATED TRUE)
+set(TL_DOTNET_SCHEME_SOURCE
+  ${TL_DOTNET_AUTO}
+  td/tl/tl_dotnet_object.h
+)
+
+set(TDLIB_SOURCE
+  td/mtproto/AuthData.cpp
+  td/mtproto/crypto.cpp
+  td/mtproto/Handshake.cpp
+  td/mtproto/HandshakeActor.cpp
+  td/mtproto/HttpTransport.cpp
+  td/mtproto/IStreamTransport.cpp
+  td/mtproto/RawConnection.cpp
+  td/mtproto/SessionConnection.cpp
+  td/mtproto/TcpTransport.cpp
+  td/mtproto/Transport.cpp
+  td/mtproto/utils.cpp
+
+  td/telegram/AnimationsManager.cpp
+  td/telegram/AudiosManager.cpp
+  td/telegram/AuthManager.cpp
+  td/telegram/CallActor.cpp
+  td/telegram/CallDiscardReason.cpp
+  td/telegram/CallManager.cpp
+  td/telegram/CallbackQueriesManager.cpp
+  td/telegram/ClientActor.cpp
+  td/telegram/ConfigManager.cpp
+  td/telegram/ConfigShared.cpp
+  td/telegram/Contact.cpp
+  td/telegram/ContactsManager.cpp
+  td/telegram/DelayDispatcher.cpp
+  td/telegram/DeviceTokenManager.cpp
+  td/telegram/DhCache.cpp
+  td/telegram/DialogDb.cpp
+  td/telegram/DialogId.cpp
+  td/telegram/DialogParticipant.cpp
+  td/telegram/DocumentsManager.cpp
+  td/telegram/files/FileDb.cpp
+  td/telegram/files/FileDownloader.cpp
+  td/telegram/files/FileFromBytes.cpp
+  td/telegram/files/FileGcParameters.cpp
+  td/telegram/files/FileGcWorker.cpp
+  td/telegram/files/FileGenerateManager.cpp
+  td/telegram/files/FileHashUploader.cpp
+  td/telegram/files/FileLoader.cpp
+  td/telegram/files/FileLoaderUtils.cpp
+  td/telegram/files/FileLoadManager.cpp
+  td/telegram/files/FileManager.cpp
+  td/telegram/files/FileStats.cpp
+  td/telegram/files/FileStatsWorker.cpp
+  td/telegram/files/FileUploader.cpp
+  td/telegram/files/PartsManager.cpp
+  td/telegram/files/ResourceManager.cpp
+  td/telegram/Game.cpp
+  td/telegram/Global.cpp
+  td/telegram/HashtagHints.cpp
+  td/telegram/InlineQueriesManager.cpp
+  td/telegram/Location.cpp
+  td/telegram/MessageEntity.cpp
+  td/telegram/MessagesDb.cpp
+  td/telegram/MessagesManager.cpp
+  td/telegram/misc.cpp
+  td/telegram/net/AuthDataShared.cpp
+  td/telegram/net/ConnectionCreator.cpp
+  td/telegram/net/DcAuthManager.cpp
+  td/telegram/net/DcOptionsSet.cpp
+  td/telegram/net/MtprotoHeader.cpp
+  td/telegram/net/NetActor.cpp
+  td/telegram/net/NetQuery.cpp
+  td/telegram/net/NetQueryCounter.cpp
+  td/telegram/net/NetQueryCreator.cpp
+  td/telegram/net/NetQueryDelayer.cpp
+  td/telegram/net/NetQueryDispatcher.cpp
+  td/telegram/net/NetStatsManager.cpp
+  td/telegram/net/PublicRsaKeyShared.cpp
+  td/telegram/net/PublicRsaKeyWatchdog.cpp
+  td/telegram/net/Session.cpp
+  td/telegram/net/SessionProxy.cpp
+  td/telegram/net/SessionMultiProxy.cpp
+  td/telegram/Payments.cpp
+  td/telegram/PasswordManager.cpp
+  td/telegram/PrivacyManager.cpp
+  td/telegram/Photo.cpp
+  td/telegram/ReplyMarkup.cpp
+  td/telegram/SecretChatActor.cpp
+  td/telegram/SecretChatDb.cpp
+  td/telegram/SecretChatsManager.cpp
+  td/telegram/SequenceDispatcher.cpp
+  td/telegram/StateManager.cpp
+  td/telegram/StickersManager.cpp
+  td/telegram/StorageManager.cpp
+  td/telegram/Td.cpp
+  td/telegram/TdDb.cpp
+  td/telegram/TopDialogManager.cpp
+  td/telegram/UpdatesManager.cpp
+  td/telegram/VideoNotesManager.cpp
+  td/telegram/VideosManager.cpp
+  td/telegram/VoiceNotesManager.cpp
+  td/telegram/WebPagesManager.cpp
+
+  td/mtproto/AuthData.h
+  td/mtproto/AuthKey.h
+  td/mtproto/crypto.h
+  td/mtproto/CryptoStorer.h
+  td/mtproto/Handshake.h
+  td/mtproto/HandshakeActor.h
+  td/mtproto/HandshakeConnection.h
+  td/mtproto/HttpTransport.h
+  td/mtproto/IStreamTransport.h
+  td/mtproto/NoCryptoStorer.h
+  td/mtproto/PacketStorer.h
+  td/mtproto/PingConnection.h
+  td/mtproto/RawConnection.h
+  td/mtproto/SessionConnection.h
+  td/mtproto/TcpTransport.h
+  td/mtproto/Transport.h
+  td/mtproto/utils.h
+
+  td/telegram/AccessRights.h
+  td/telegram/AnimationsManager.h
+  td/telegram/AudiosManager.h
+  td/telegram/AuthManager.h
+  td/telegram/CallActor.h
+  td/telegram/CallDiscardReason.h
+  td/telegram/CallId.h
+  td/telegram/CallManager.h
+  td/telegram/CallbackQueriesManager.h
+  td/telegram/ChannelId.h
+  td/telegram/ChatId.h
+  td/telegram/ClientActor.h
+  td/telegram/ConfigManager.h
+  td/telegram/ConfigShared.h
+  td/telegram/Contact.h
+  td/telegram/ContactsManager.h
+  td/telegram/DelayDispatcher.h
+  td/telegram/DeviceTokenManager.h
+  td/telegram/DhCache.h
+  td/telegram/DhConfig.h
+  td/telegram/DialogDb.h
+  td/telegram/DialogId.h
+  td/telegram/DialogParticipant.h
+  td/telegram/DocumentsManager.h
+  td/telegram/files/FileDb.h
+  td/telegram/files/FileDownloader.h
+  td/telegram/files/FileFromBytes.h
+  td/telegram/files/FileGcParameters.h
+  td/telegram/files/FileGcWorker.h
+  td/telegram/files/FileGenerateManager.h
+  td/telegram/files/FileHashUploader.h
+  td/telegram/files/FileId.h
+  td/telegram/files/FileLoaderActor.h
+  td/telegram/files/FileLoader.h
+  td/telegram/files/FileLoaderUtils.h
+  td/telegram/files/FileLoadManager.h
+  td/telegram/files/FileLocation.h
+  td/telegram/files/FileManager.h
+  td/telegram/files/FileStats.h
+  td/telegram/files/FileStatsWorker.h
+  td/telegram/files/FileUploader.h
+  td/telegram/files/PartsManager.h
+  td/telegram/files/ResourceManager.h
+  td/telegram/files/ResourceState.h
+  td/telegram/Game.h
+  td/telegram/Global.h
+  td/telegram/HashtagHints.h
+  td/telegram/InlineQueriesManager.h
+  td/telegram/Location.h
+  td/telegram/logevent/LogEvent.h
+  td/telegram/logevent/SecretChatEvent.h
+  td/telegram/MessageEntity.h
+  td/telegram/MessageId.h
+  td/telegram/MessagesDb.h
+  td/telegram/MessagesManager.h
+  td/telegram/misc.h
+  td/telegram/net/AuthDataShared.h
+  td/telegram/net/ConnectionCreator.h
+  td/telegram/net/DcAuthManager.h
+  td/telegram/net/DcId.h
+  td/telegram/net/DcOptions.h
+  td/telegram/net/DcOptionsSet.h
+  td/telegram/net/MtprotoHeader.h
+  td/telegram/net/NetActor.h
+  td/telegram/net/NetQuery.h
+  td/telegram/net/NetQueryCounter.h
+  td/telegram/net/NetQueryCreator.h
+  td/telegram/net/NetQueryDelayer.h
+  td/telegram/net/NetQueryDispatcher.h
+  td/telegram/net/NetStatsManager.h
+  td/telegram/net/NetType.h
+  td/telegram/net/PublicRsaKeyShared.h
+  td/telegram/net/PublicRsaKeyWatchdog.h
+  td/telegram/net/Session.h
+  td/telegram/net/SessionProxy.h
+  td/telegram/net/SessionMultiProxy.h
+  td/telegram/net/TempAuthKeyWatchdog.h
+  td/telegram/PasswordManager.h
+  td/telegram/Payments.h
+  td/telegram/Photo.h
+  td/telegram/PrivacyManager.h
+  td/telegram/PtsManager.h
+  td/telegram/ReplyMarkup.h
+  td/telegram/SecretChatActor.h
+  td/telegram/SecretChatId.h
+  td/telegram/SecretChatDb.h
+  td/telegram/SecretChatsManager.h
+  td/telegram/SecretInputMedia.h
+  td/telegram/SequenceDispatcher.h
+  td/telegram/StateManager.h
+  td/telegram/StickersManager.h
+  td/telegram/StorageManager.h
+  td/telegram/Td.h
+  td/telegram/TdCallback.h
+  td/telegram/TdDb.h
+  td/telegram/TdParameters.h
+  td/telegram/TopDialogManager.h
+  td/telegram/UniqueId.h
+  td/telegram/UpdatesManager.h
+  td/telegram/UserId.h
+  td/telegram/Version.h
+  td/telegram/VideoNotesManager.h
+  td/telegram/VideosManager.h
+  td/telegram/VoiceNotesManager.h
+  td/telegram/WebPageId.h
+  td/telegram/WebPagesManager.h
+
+  td/telegram/AnimationsManager.hpp
+  td/telegram/AudiosManager.hpp
+  td/telegram/AuthManager.hpp
+  td/telegram/DocumentsManager.hpp
+  td/telegram/files/FileId.hpp
+  td/telegram/files/FileManager.hpp
+  td/telegram/Game.hpp
+  td/telegram/Payments.hpp
+  td/telegram/Photo.hpp
+  td/telegram/ReplyMarkup.hpp
+  td/telegram/StickersManager.hpp
+  td/telegram/VideoNotesManager.hpp
+  td/telegram/VideosManager.hpp
+  td/telegram/VoiceNotesManager.hpp
+
+  ${TL_TD_SCHEME_SOURCE}
+)
+
+set(MEMPROF_SOURCE
+  memprof/memprof.cpp
+  memprof/memprof.h
+)
+
+#RULES
+
+file(MAKE_DIRECTORY auto)
+
+if (WIN32)
+  set(GIT_COMMIT_CMD powershell -ExecutionPolicy ByPass ./gen_git_commit_h.ps1)
+else()
+  set(GIT_COMMIT_CMD ./gen_git_commit_h.sh)
+endif()
+
+add_custom_target(git_commit ALL
+  WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+  COMMAND ${GIT_COMMIT_CMD}
+  COMMENT "Generate git_commit.h"
+)
+
+#LIBRARIES
+
+# memprof - simple library for memory usage profiling
+add_library(memprof STATIC ${MEMPROF_SOURCE})
+target_include_directories(memprof PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>)
+target_link_libraries(memprof PRIVATE tdutils)
+if (MEMPROF)
+  target_compile_definitions(memprof PRIVATE -DUSE_MEMPROF=1)
+  if (MEMPROF STREQUAL "SAFE")
+    target_compile_definitions(memprof PRIVATE -DUSE_MEMPROF_SAFE=1)
+  elseif (MEMPROF STREQUAL "FAST")
+    target_compile_definitions(memprof PRIVATE -DUSE_MEMPROF_FAST=1)
+  elseif (NOT ${MEMPROF})
+    message(FATAL_ERROR "Unsupported MEMPROF value \"${MEMPROF}\"")
+  endif()
+endif()
+
+
+# tdcore - mostly internal TDLib interface. One should use tdactor for interactions with it.
+add_library(tdcore STATIC ${TDLIB_SOURCE})
+target_include_directories(tdcore PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}> $<BUILD_INTERFACE:${TL_TD_AUTO_INCLUDES}>)
+target_include_directories(tdcore SYSTEM PRIVATE ${OPENSSL_INCLUDE_DIR})
+target_link_libraries(tdcore PUBLIC tdactor tdutils tdnet tddb PRIVATE ${OPENSSL_CRYPTO_LIBRARY} ${CMAKE_DL_LIBS} ${ZLIB_LIBRARIES})
+
+if (TD_ENABLE_JNI AND NOT ANDROID) # jni is available by default on Android
+  if (NOT JNI_FOUND)
+    find_package(JNI REQUIRED)
+  endif()
+  message(STATUS "Found JNI: ${JNI_INCLUDE_DIRS} ${JNI_LIBRARIES}")
+  target_include_directories(tdcore PUBLIC ${JAVA_INCLUDE_PATH} ${JAVA_INCLUDE_PATH2})
+  target_link_libraries(tdcore PUBLIC ${JAVA_JVM_LIBRARY})
+endif()
+
+if (NOT CMAKE_CROSSCOMPILING)
+  add_dependencies(tdcore tl_generate_common)
+  if (TD_ENABLE_JNI)
+    add_dependencies(tdcore td_generate_java_api)
+  endif()
+  if (TD_ENABLE_DOTNET)
+    add_dependencies(tdcore remove_cpp_documentation)
+  endif()
+endif()
+
+add_library(tdclient td/telegram/Client.cpp td/telegram/Client.h td/telegram/Log.cpp td/telegram/Log.h)
+target_include_directories(tdclient PUBLIC
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+  $<BUILD_INTERFACE:${TL_TD_AUTO_INCLUDES}>
+)
+target_link_libraries(tdclient PRIVATE tdcore)
+
+if (TD_ENABLE_JNI AND NOT ANDROID) # jni is available by default on Android
+  target_include_directories(tdclient PUBLIC ${JAVA_INCLUDE_PATH} ${JAVA_INCLUDE_PATH2})
+  target_link_libraries(tdclient PUBLIC ${JAVA_JVM_LIBRARY})
+endif()
+
+if (TD_ENABLE_DOTNET)
+  add_library(tddotnet SHARED
+    td/telegram/ClientDotNet.cpp
+    td/telegram/LogDotNet.cpp
+    ${TL_DOTNET_SCHEME_SOURCE}
+  )
+  set(VCPKG_APPLOCAL_LIBRARY_DEPS ON)
+  set_target_properties(tddotnet PROPERTIES OUTPUT_NAME Telegram.Td)
+  target_link_libraries(tddotnet PRIVATE tdclient tdutils)
+  target_include_directories(tddotnet PUBLIC
+    $<BUILD_INTERFACE:${TL_TD_AUTO_INCLUDES}>
+  )
+  if (NOT CMAKE_CROSSCOMPILING)
+    add_dependencies(tddotnet generate_dotnet_api)
+  endif()
+
+  target_compile_options(tddotnet PRIVATE "/doc")
+  if ("${CMAKE_SYSTEM_NAME}" STREQUAL "WindowsStore")
+    set_target_properties(tddotnet PROPERTIES VS_WINRT_COMPONENT "true")
+    target_compile_options(tddotnet PUBLIC "/ZW")
+  else()
+    set_target_properties(tddotnet PROPERTIES COMPILE_FLAGS "/GR /clr")
+    target_compile_options(tddotnet PUBLIC "/EHa")
+  endif()
+endif()
+
+# tdc - TDLib interface in pure c.
+add_library(tdc STATIC ${TL_C_SCHEME_SOURCE} td/telegram/td_c_client.cpp td/telegram/td_c_client.h)
+target_include_directories(tdc PUBLIC
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+  $<BUILD_INTERFACE:${TL_TD_AUTO_INCLUDES}>)
+target_link_libraries(tdc PRIVATE tdclient tdutils)
+if (NOT CMAKE_CROSSCOMPILING)
+  add_dependencies(tdc tl_generate_c)
+endif()
+
+add_library(tdjson_private STATIC ${TL_TD_JSON} td/telegram/ClientJson.cpp td/telegram/ClientJson.h)
+target_include_directories(tdjson_private PUBLIC
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+  $<BUILD_INTERFACE:${TL_TD_AUTO_INCLUDES}>)
+target_link_libraries(tdjson_private PUBLIC tdclient tdutils)
+if (NOT CMAKE_CROSSCOMPILING)
+  add_dependencies(tdjson_private tl_generate_common tl_generate_json)
+  if (TD_ENABLE_DOTNET)
+    add_dependencies(tdjson_private remove_cpp_documentation)
+  endif()
+endif()
+
+set(TD_JSON_HEADERS td/telegram/td_json_client.h td/telegram/td_log.h)
+set(TD_JSON_SOURCE td/telegram/td_json_client.cpp td/telegram/td_log.cpp)
+
+include(GenerateExportHeader)
+
+add_library(tdjson SHARED ${TD_JSON_SOURCE} ${TD_JSON_HEADERS})
+target_link_libraries(tdjson PRIVATE tdjson_private)
+generate_export_header(tdjson EXPORT_FILE_NAME ${CMAKE_CURRENT_BINARY_DIR}/td/telegram/tdjson_export.h)
+target_include_directories(tdjson PUBLIC
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}>
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>)
+if (APPLE)
+  set_target_properties(tdjson PROPERTIES LINK_FLAGS "-Wl,-exported_symbols_list,${CMAKE_CURRENT_SOURCE_DIR}/tdclientjson_export_list")
+endif()
+
+add_library(tdjson_static STATIC ${TD_JSON_SOURCE} ${TD_JSON_HEADERS})
+target_link_libraries(tdjson_static PRIVATE tdjson_private)
+target_compile_definitions(tdjson_static PUBLIC TDJSON_STATIC_DEFINE)
+target_include_directories(tdjson_static PUBLIC
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}>
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>)
+
+set(BIGOBJ)
+if (WIN32 OR CYGWIN)
+  if (MSVC)
+    set(BIGOBJ "/bigobj")
+  elseif (GCC)
+    set(BIGOBJ "-Wa,-mbig-obj")
+  endif()
+endif()
+if (BIGOBJ)
+  target_compile_options(tdc PUBLIC ${BIGOBJ})
+  target_compile_options(tdcore PUBLIC ${BIGOBJ})
+  target_compile_options(tdclient PUBLIC ${BIGOBJ})
+  target_compile_options(tdjson PUBLIC ${BIGOBJ})
+  target_compile_options(tdjson_static PUBLIC ${BIGOBJ})
+  if (TD_ENABLE_DOTNET)
+    target_compile_options(tddotnet PUBLIC "/bigobj")
+  endif()
+endif()
+
+if (EMSCRIPTEN)
+  set(TD_EMSCRIPTEN_SRC td/telegram/td_emscripten.cpp)
+  add_executable(${TD_EMSCRIPTEN} ${TD_EMSCRIPTEN_SRC})
+  target_include_directories(${TD_EMSCRIPTEN} PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>)
+  target_link_libraries(${TD_EMSCRIPTEN} PRIVATE tdjson_static)
+endif()
+
+#EXECUTABLES
+if (NOT CMAKE_CROSSCOMPILING)
+  add_executable(tg_cli td/telegram/cli.cpp ${TL_TD_JSON})
+
+  if (NOT READLINE_FOUND)
+    find_package(Readline)
+  endif()
+  if (NOT READLINE_FOUND)
+    message(STATUS "Could NOT find Readline")
+  else()
+    message(STATUS "Found Readline: ${READLINE_INCLUDE_DIR} ${READLINE_LIBRARY}")
+    target_link_libraries(tg_cli PRIVATE ${READLINE_LIBRARY})
+    target_include_directories(tg_cli SYSTEM PRIVATE ${READLINE_INCLUDE_DIR})
+    target_compile_definitions(tg_cli PRIVATE -DUSE_READLINE=1)
+  endif()
+  target_link_libraries(tg_cli PRIVATE memprof tdclient tdcore tdtl)
+  add_dependencies(tg_cli tl_generate_json)
+endif()
+
+#Exported libraries
+add_library(TdStatic INTERFACE)
+target_link_libraries(TdStatic INTERFACE tdclient)
+
+add_library(TdJson INTERFACE)
+target_link_libraries(TdJson INTERFACE tdjson)
+
+add_library(TdJsonStatic INTERFACE)
+target_link_libraries(TdJsonStatic INTERFACE tdjson_static)
+
+add_library(Td::TdStatic ALIAS TdStatic)
+add_library(Td::TdJson ALIAS TdJson)
+add_library(Td::TdJsonStatic ALIAS TdJsonStatic)
+
+install(TARGETS tdjson TdJson tdjson_static TdJsonStatic tdjson_private tdclient tdcore TdStatic EXPORT TdTargets
+  LIBRARY DESTINATION lib
+  ARCHIVE DESTINATION lib
+  RUNTIME DESTINATION bin
+  INCLUDES DESTINATION include
+)
+
+install(EXPORT TdTargets
+  FILE TdTargets.cmake
+  NAMESPACE Td::
+  DESTINATION lib/cmake/Td
+)
+
+install(FILES ${TD_JSON_HEADERS} ${CMAKE_CURRENT_BINARY_DIR}/td/telegram/tdjson_export.h DESTINATION include/td/telegram)
+install(FILES td/telegram/Client.h td/telegram/Log.h DESTINATION include/td/telegram)
+install(FILES td/tl/TlObject.h DESTINATION include/td/tl)
+install(FILES ${TL_TD_AUTO_INCLUDES}/td/telegram/td_api.h ${TL_TD_AUTO_INCLUDES}/td/telegram/td_api.hpp DESTINATION include/td/telegram)
+if (TD_ENABLE_JNI)
+  install(FILES td/tl/tl_jni_object.h DESTINATION include/td/tl)
+endif()
+
+include(CMakePackageConfigHelpers)
+write_basic_package_version_file("TdConfigVersion.cmake"
+  VERSION ${TDLib_VERSION}
+  COMPATIBILITY ExactVersion
+)
+install(FILES "TdConfig.cmake" "${CMAKE_CURRENT_BINARY_DIR}/TdConfigVersion.cmake"
+  DESTINATION lib/cmake/Td
+)
diff --git a/libs/tdlib/td/Doxyfile b/libs/tdlib/td/Doxyfile
new file mode 100644
index 0000000000..e9e26e2d5d
--- /dev/null
+++ b/libs/tdlib/td/Doxyfile
@@ -0,0 +1,2473 @@
+# Doxyfile 1.8.13
+
+# This file describes the settings to be used by the documentation system
+# doxygen (www.doxygen.org) for a project.
+#
+# All text after a double hash (##) is considered a comment and is placed in
+# front of the TAG it is preceding.
+#
+# All text after a single hash (#) is considered a comment and will be ignored.
+# The format is:
+# TAG = value [value, ...]
+# For lists, items can also be appended using:
+# TAG += value [value, ...]
+# Values that contain spaces should be placed between quotes (\" \").
+
+#---------------------------------------------------------------------------
+# Project related configuration options
+#---------------------------------------------------------------------------
+
+# This tag specifies the encoding used for all characters in the config file
+# that follow. The default is UTF-8 which is also the encoding used for all text
+# before the first occurrence of this tag. Doxygen uses libiconv (or the iconv
+# built into libc) for the transcoding. See http://www.gnu.org/software/libiconv
+# for the list of possible encodings.
+# The default value is: UTF-8.
+
+DOXYFILE_ENCODING      = UTF-8
+
+# The PROJECT_NAME tag is a single word (or a sequence of words surrounded by
+# double-quotes, unless you are using Doxywizard) that should identify the
+# project for which the documentation is generated. This name is used in the
+# title of most generated pages and in a few other places.
+# The default value is: My Project.
+
+PROJECT_NAME           = "TDLib"
+
+# The PROJECT_NUMBER tag can be used to enter a project or revision number. This
+# could be handy for archiving the generated documentation or if some version
+# control system is used.
+
+PROJECT_NUMBER         =
+
+# Using the PROJECT_BRIEF tag one can provide an optional one line description
+# for a project that appears at the top of each page and should give viewer a
+# quick idea about the purpose of the project. Keep the description short.
+
+PROJECT_BRIEF          =
+
+# With the PROJECT_LOGO tag one can specify a logo or an icon that is included
+# in the documentation. The maximum height of the logo should not exceed 55
+# pixels and the maximum width should not exceed 200 pixels. Doxygen will copy
+# the logo to the output directory.
+
+PROJECT_LOGO           =
+
+# The OUTPUT_DIRECTORY tag is used to specify the (relative or absolute) path
+# into which the generated documentation will be written. If a relative path is
+# entered, it will be relative to the location where doxygen was started. If
+# left blank the current directory will be used.
+
+OUTPUT_DIRECTORY       = "docs"
+
+# If the CREATE_SUBDIRS tag is set to YES then doxygen will create 4096 sub-
+# directories (in 2 levels) under the output directory of each output format and
+# will distribute the generated files over these directories. Enabling this
+# option can be useful when feeding doxygen a huge amount of source files, where
+# putting all generated files in the same directory would otherwise causes
+# performance problems for the file system.
+# The default value is: NO.
+
+CREATE_SUBDIRS         = NO
+
+# If the ALLOW_UNICODE_NAMES tag is set to YES, doxygen will allow non-ASCII
+# characters to appear in the names of generated files. If set to NO, non-ASCII
+# characters will be escaped, for example _xE3_x81_x84 will be used for Unicode
+# U+3044.
+# The default value is: NO.
+
+ALLOW_UNICODE_NAMES    = NO
+
+# The OUTPUT_LANGUAGE tag is used to specify the language in which all
+# documentation generated by doxygen is written. Doxygen will use this
+# information to generate all constant output in the proper language.
+# Possible values are: Afrikaans, Arabic, Armenian, Brazilian, Catalan, Chinese,
+# Chinese-Traditional, Croatian, Czech, Danish, Dutch, English (United States),
+# Esperanto, Farsi (Persian), Finnish, French, German, Greek, Hungarian,
+# Indonesian, Italian, Japanese, Japanese-en (Japanese with English messages),
+# Korean, Korean-en (Korean with English messages), Latvian, Lithuanian,
+# Macedonian, Norwegian, Persian (Farsi), Polish, Portuguese, Romanian, Russian,
+# Serbian, Serbian-Cyrillic, Slovak, Slovene, Spanish, Swedish, Turkish,
+# Ukrainian and Vietnamese.
+# The default value is: English.
+
+OUTPUT_LANGUAGE        = English
+
+# If the BRIEF_MEMBER_DESC tag is set to YES, doxygen will include brief member
+# descriptions after the members that are listed in the file and class
+# documentation (similar to Javadoc). Set to NO to disable this.
+# The default value is: YES.
+
+BRIEF_MEMBER_DESC      = YES
+
+# If the REPEAT_BRIEF tag is set to YES, doxygen will prepend the brief
+# description of a member or function before the detailed description
+#
+# Note: If both HIDE_UNDOC_MEMBERS and BRIEF_MEMBER_DESC are set to NO, the
+# brief descriptions will be completely suppressed.
+# The default value is: YES.
+
+REPEAT_BRIEF           = YES
+
+# This tag implements a quasi-intelligent brief description abbreviator that is
+# used to form the text in various listings. Each string in this list, if found
+# as the leading text of the brief description, will be stripped from the text
+# and the result, after processing the whole list, is used as the annotated
+# text. Otherwise, the brief description is used as-is. If left blank, the
+# following values are used ($name is automatically replaced with the name of
+# the entity):The $name class, The $name widget, The $name file, is, provides,
+# specifies, contains, represents, a, an and the.
+
+ABBREVIATE_BRIEF       = "The $name class" \
+                         "The $name widget" \
+                         "The $name file" \
+                         is \
+                         provides \
+                         specifies \
+                         contains \
+                         represents \
+                         a \
+                         an \
+                         the
+
+# If the ALWAYS_DETAILED_SEC and REPEAT_BRIEF tags are both set to YES then
+# doxygen will generate a detailed section even if there is only a brief
+# description.
+# The default value is: NO.
+
+ALWAYS_DETAILED_SEC    = NO
+
+# If the INLINE_INHERITED_MEMB tag is set to YES, doxygen will show all
+# inherited members of a class in the documentation of that class as if those
+# members were ordinary class members. Constructors, destructors and assignment
+# operators of the base classes will not be shown.
+# The default value is: NO.
+
+INLINE_INHERITED_MEMB  = NO
+
+# If the FULL_PATH_NAMES tag is set to YES, doxygen will prepend the full path
+# before files name in the file list and in the header files. If set to NO the
+# shortest path that makes the file name unique will be used
+# The default value is: YES.
+
+FULL_PATH_NAMES        = YES
+
+# The STRIP_FROM_PATH tag can be used to strip a user-defined part of the path.
+# Stripping is only done if one of the specified strings matches the left-hand
+# part of the path. The tag can be used to show relative paths in the file list.
+# If left blank the directory from which doxygen is run is used as the path to
+# strip.
+#
+# Note that you can specify absolute paths here, but also relative paths, which
+# will be relative from the directory where doxygen is started.
+# This tag requires that the tag FULL_PATH_NAMES is set to YES.
+
+STRIP_FROM_PATH        =
+
+# The STRIP_FROM_INC_PATH tag can be used to strip a user-defined part of the
+# path mentioned in the documentation of a class, which tells the reader which
+# header file to include in order to use a class. If left blank only the name of
+# the header file containing the class definition is used. Otherwise one should
+# specify the list of include paths that are normally passed to the compiler
+# using the -I flag.
+
+STRIP_FROM_INC_PATH    = td/generate/auto/ .
+
+# If the SHORT_NAMES tag is set to YES, doxygen will generate much shorter (but
+# less readable) file names. This can be useful is your file systems doesn't
+# support long names like on DOS, Mac, or CD-ROM.
+# The default value is: NO.
+
+SHORT_NAMES            = NO
+
+# If the JAVADOC_AUTOBRIEF tag is set to YES then doxygen will interpret the
+# first line (until the first dot) of a Javadoc-style comment as the brief
+# description. If set to NO, the Javadoc-style will behave just like regular Qt-
+# style comments (thus requiring an explicit @brief command for a brief
+# description.)
+# The default value is: NO.
+
+JAVADOC_AUTOBRIEF      = NO
+
+# If the QT_AUTOBRIEF tag is set to YES then doxygen will interpret the first
+# line (until the first dot) of a Qt-style comment as the brief description. If
+# set to NO, the Qt-style will behave just like regular Qt-style comments (thus
+# requiring an explicit \brief command for a brief description.)
+# The default value is: NO.
+
+QT_AUTOBRIEF           = NO
+
+# The MULTILINE_CPP_IS_BRIEF tag can be set to YES to make doxygen treat a
+# multi-line C++ special comment block (i.e. a block of //! or /// comments) as
+# a brief description. This used to be the default behavior. The new default is
+# to treat a multi-line C++ comment block as a detailed description. Set this
+# tag to YES if you prefer the old behavior instead.
+#
+# Note that setting this tag to YES also means that rational rose comments are
+# not recognized any more.
+# The default value is: NO.
+
+MULTILINE_CPP_IS_BRIEF = NO
+
+# If the INHERIT_DOCS tag is set to YES then an undocumented member inherits the
+# documentation from any documented member that it re-implements.
+# The default value is: YES.
+
+INHERIT_DOCS           = YES
+
+# If the SEPARATE_MEMBER_PAGES tag is set to YES then doxygen will produce a new
+# page for each member. If set to NO, the documentation of a member will be part
+# of the file/class/namespace that contains it.
+# The default value is: NO.
+
+SEPARATE_MEMBER_PAGES  = NO
+
+# The TAB_SIZE tag can be used to set the number of spaces in a tab. Doxygen
+# uses this value to replace tabs by spaces in code fragments.
+# Minimum value: 1, maximum value: 16, default value: 4.
+
+TAB_SIZE               = 4
+
+# This tag can be used to specify a number of aliases that act as commands in
+# the documentation. An alias has the form:
+# name=value
+# For example adding
+# "sideeffect=@par Side Effects:\n"
+# will allow you to put the command \sideeffect (or @sideeffect) in the
+# documentation, which will result in a user-defined paragraph with heading
+# "Side Effects:". You can put \n's in the value part of an alias to insert
+# newlines.
+
+ALIASES                =
+
+# This tag can be used to specify a number of word-keyword mappings (TCL only).
+# A mapping has the form "name=value". For example adding "class=itcl::class"
+# will allow you to use the command class in the itcl::class meaning.
+
+TCL_SUBST              =
+
+# Set the OPTIMIZE_OUTPUT_FOR_C tag to YES if your project consists of C sources
+# only. Doxygen will then generate output that is more tailored for C. For
+# instance, some of the names that are used will be different. The list of all
+# members will be omitted, etc.
+# The default value is: NO.
+
+OPTIMIZE_OUTPUT_FOR_C  = NO
+
+# Set the OPTIMIZE_OUTPUT_JAVA tag to YES if your project consists of Java or
+# Python sources only. Doxygen will then generate output that is more tailored
+# for that language. For instance, namespaces will be presented as packages,
+# qualified scopes will look different, etc.
+# The default value is: NO.
+
+OPTIMIZE_OUTPUT_JAVA   = NO
+
+# Set the OPTIMIZE_FOR_FORTRAN tag to YES if your project consists of Fortran
+# sources. Doxygen will then generate output that is tailored for Fortran.
+# The default value is: NO.
+
+OPTIMIZE_FOR_FORTRAN   = NO
+
+# Set the OPTIMIZE_OUTPUT_VHDL tag to YES if your project consists of VHDL
+# sources. Doxygen will then generate output that is tailored for VHDL.
+# The default value is: NO.
+
+OPTIMIZE_OUTPUT_VHDL   = NO
+
+# Doxygen selects the parser to use depending on the extension of the files it
+# parses. With this tag you can assign which parser to use for a given
+# extension. Doxygen has a built-in mapping, but you can override or extend it
+# using this tag. The format is ext=language, where ext is a file extension, and
+# language is one of the parsers supported by doxygen: IDL, Java, Javascript,
+# C#, C, C++, D, PHP, Objective-C, Python, Fortran (fixed format Fortran:
+# FortranFixed, free formatted Fortran: FortranFree, unknown formatted Fortran:
+# Fortran. In the later case the parser tries to guess whether the code is fixed
+# or free formatted code, this is the default for Fortran type files), VHDL. For
+# instance to make doxygen treat .inc files as Fortran files (default is PHP),
+# and .f files as C (default is Fortran), use: inc=Fortran f=C.
+#
+# Note: For files without extension you can use no_extension as a placeholder.
+#
+# Note that for custom extensions you also need to set FILE_PATTERNS otherwise
+# the files are not read by doxygen.
+
+EXTENSION_MAPPING      =
+
+# If the MARKDOWN_SUPPORT tag is enabled then doxygen pre-processes all comments
+# according to the Markdown format, which allows for more readable
+# documentation. See http://daringfireball.net/projects/markdown/ for details.
+# The output of markdown processing is further processed by doxygen, so you can
+# mix doxygen, HTML, and XML commands with Markdown formatting. Disable only in
+# case of backward compatibilities issues.
+# The default value is: YES.
+
+MARKDOWN_SUPPORT       = YES
+
+# When the TOC_INCLUDE_HEADINGS tag is set to a non-zero value, all headings up
+# to that level are automatically included in the table of contents, even if
+# they do not have an id attribute.
+# Note: This feature currently applies only to Markdown headings.
+# Minimum value: 0, maximum value: 99, default value: 0.
+# This tag requires that the tag MARKDOWN_SUPPORT is set to YES.
+
+TOC_INCLUDE_HEADINGS   = 0
+
+# When enabled doxygen tries to link words that correspond to documented
+# classes, or namespaces to their corresponding documentation. Such a link can
+# be prevented in individual cases by putting a % sign in front of the word or
+# globally by setting AUTOLINK_SUPPORT to NO.
+# The default value is: YES.
+
+AUTOLINK_SUPPORT       = YES
+
+# If you use STL classes (i.e. std::string, std::vector, etc.) but do not want
+# to include (a tag file for) the STL sources as input, then you should set this
+# tag to YES in order to let doxygen match functions declarations and
+# definitions whose arguments contain STL classes (e.g. func(std::string);
+# versus func(std::string) {}). This also make the inheritance and collaboration
+# diagrams that involve STL classes more complete and accurate.
+# The default value is: NO.
+
+BUILTIN_STL_SUPPORT    = YES
+
+# If you use Microsoft's C++/CLI language, you should set this option to YES to
+# enable parsing support.
+# The default value is: NO.
+
+CPP_CLI_SUPPORT        = NO
+
+# Set the SIP_SUPPORT tag to YES if your project consists of sip (see:
+# http://www.riverbankcomputing.co.uk/software/sip/intro) sources only. Doxygen
+# will parse them like normal C++ but will assume all classes use public instead
+# of private inheritance when no explicit protection keyword is present.
+# The default value is: NO.
+
+SIP_SUPPORT            = NO
+
+# For Microsoft's IDL there are propget and propput attributes to indicate
+# getter and setter methods for a property. Setting this option to YES will make
+# doxygen to replace the get and set methods by a property in the documentation.
+# This will only work if the methods are indeed getting or setting a simple
+# type. If this is not the case, or you want to show the methods anyway, you
+# should set this option to NO.
+# The default value is: YES.
+
+IDL_PROPERTY_SUPPORT   = YES
+
+# If member grouping is used in the documentation and the DISTRIBUTE_GROUP_DOC
+# tag is set to YES then doxygen will reuse the documentation of the first
+# member in the group (if any) for the other members of the group. By default
+# all members of a group must be documented explicitly.
+# The default value is: NO.
+
+DISTRIBUTE_GROUP_DOC   = NO
+
+# If one adds a struct or class to a group and this option is enabled, then also
+# any nested class or struct is added to the same group. By default this option
+# is disabled and one has to add nested compounds explicitly via \ingroup.
+# The default value is: NO.
+
+GROUP_NESTED_COMPOUNDS = NO
+
+# Set the SUBGROUPING tag to YES to allow class member groups of the same type
+# (for instance a group of public functions) to be put as a subgroup of that
+# type (e.g. under the Public Functions section). Set it to NO to prevent
+# subgrouping. Alternatively, this can be done per class using the
+# \nosubgrouping command.
+# The default value is: YES.
+
+SUBGROUPING            = YES
+
+# When the INLINE_GROUPED_CLASSES tag is set to YES, classes, structs and unions
+# are shown inside the group in which they are included (e.g. using \ingroup)
+# instead of on a separate page (for HTML and Man pages) or section (for LaTeX
+# and RTF).
+#
+# Note that this feature does not work in combination with
+# SEPARATE_MEMBER_PAGES.
+# The default value is: NO.
+
+INLINE_GROUPED_CLASSES = NO
+
+# When the INLINE_SIMPLE_STRUCTS tag is set to YES, structs, classes, and unions
+# with only public data fields or simple typedef fields will be shown inline in
+# the documentation of the scope in which they are defined (i.e. file,
+# namespace, or group documentation), provided this scope is documented. If set
+# to NO, structs, classes, and unions are shown on a separate page (for HTML and
+# Man pages) or section (for LaTeX and RTF).
+# The default value is: NO.
+
+INLINE_SIMPLE_STRUCTS  = NO
+
+# When TYPEDEF_HIDES_STRUCT tag is enabled, a typedef of a struct, union, or
+# enum is documented as struct, union, or enum with the name of the typedef. So
+# typedef struct TypeS {} TypeT, will appear in the documentation as a struct
+# with name TypeT. When disabled the typedef will appear as a member of a file,
+# namespace, or class. And the struct will be named TypeS. This can typically be
+# useful for C code in case the coding convention dictates that all compound
+# types are typedef'ed and only the typedef is referenced, never the tag name.
+# The default value is: NO.
+
+TYPEDEF_HIDES_STRUCT   = NO
+
+# The size of the symbol lookup cache can be set using LOOKUP_CACHE_SIZE. This
+# cache is used to resolve symbols given their name and scope. Since this can be
+# an expensive process and often the same symbol appears multiple times in the
+# code, doxygen keeps a cache of pre-resolved symbols. If the cache is too small
+# doxygen will become slower. If the cache is too large, memory is wasted. The
+# cache size is given by this formula: 2^(16+LOOKUP_CACHE_SIZE). The valid range
+# is 0..9, the default is 0, corresponding to a cache size of 2^16=65536
+# symbols. At the end of a run doxygen will report the cache usage and suggest
+# the optimal cache size from a speed point of view.
+# Minimum value: 0, maximum value: 9, default value: 0.
+
+LOOKUP_CACHE_SIZE      = 0
+
+#---------------------------------------------------------------------------
+# Build related configuration options
+#---------------------------------------------------------------------------
+
+# If the EXTRACT_ALL tag is set to YES, doxygen will assume all entities in
+# documentation are documented, even if no documentation was available. Private
+# class members and static file members will be hidden unless the
+# EXTRACT_PRIVATE respectively EXTRACT_STATIC tags are set to YES.
+# Note: This will also disable the warnings about undocumented members that are
+# normally produced when WARNINGS is set to YES.
+# The default value is: NO.
+
+EXTRACT_ALL            = NO
+
+# If the EXTRACT_PRIVATE tag is set to YES, all private members of a class will
+# be included in the documentation.
+# The default value is: NO.
+
+EXTRACT_PRIVATE        = NO
+
+# If the EXTRACT_PACKAGE tag is set to YES, all members with package or internal
+# scope will be included in the documentation.
+# The default value is: NO.
+
+EXTRACT_PACKAGE        = NO
+
+# If the EXTRACT_STATIC tag is set to YES, all static members of a file will be
+# included in the documentation.
+# The default value is: NO.
+
+EXTRACT_STATIC         = NO
+
+# If the EXTRACT_LOCAL_CLASSES tag is set to YES, classes (and structs) defined
+# locally in source files will be included in the documentation. If set to NO,
+# only classes defined in header files are included. Does not have any effect
+# for Java sources.
+# The default value is: YES.
+
+EXTRACT_LOCAL_CLASSES  = YES
+
+# This flag is only useful for Objective-C code. If set to YES, local methods,
+# which are defined in the implementation section but not in the interface are
+# included in the documentation. If set to NO, only methods in the interface are
+# included.
+# The default value is: NO.
+
+EXTRACT_LOCAL_METHODS  = NO
+
+# If this flag is set to YES, the members of anonymous namespaces will be
+# extracted and appear in the documentation as a namespace called
+# 'anonymous_namespace{file}', where file will be replaced with the base name of
+# the file that contains the anonymous namespace. By default anonymous namespace
+# are hidden.
+# The default value is: NO.
+
+EXTRACT_ANON_NSPACES   = NO
+
+# If the HIDE_UNDOC_MEMBERS tag is set to YES, doxygen will hide all
+# undocumented members inside documented classes or files. If set to NO these
+# members will be included in the various overviews, but no documentation
+# section is generated. This option has no effect if EXTRACT_ALL is enabled.
+# The default value is: NO.
+
+HIDE_UNDOC_MEMBERS     = NO
+
+# If the HIDE_UNDOC_CLASSES tag is set to YES, doxygen will hide all
+# undocumented classes that are normally visible in the class hierarchy. If set
+# to NO, these classes will be included in the various overviews. This option
+# has no effect if EXTRACT_ALL is enabled.
+# The default value is: NO.
+
+HIDE_UNDOC_CLASSES     = NO
+
+# If the HIDE_FRIEND_COMPOUNDS tag is set to YES, doxygen will hide all friend
+# (class|struct|union) declarations. If set to NO, these declarations will be
+# included in the documentation.
+# The default value is: NO.
+
+HIDE_FRIEND_COMPOUNDS  = NO
+
+# If the HIDE_IN_BODY_DOCS tag is set to YES, doxygen will hide any
+# documentation blocks found inside the body of a function. If set to NO, these
+# blocks will be appended to the function's detailed documentation block.
+# The default value is: NO.
+
+HIDE_IN_BODY_DOCS      = NO
+
+# The INTERNAL_DOCS tag determines if documentation that is typed after a
+# \internal command is included. If the tag is set to NO then the documentation
+# will be excluded. Set it to YES to include the internal documentation.
+# The default value is: NO.
+
+INTERNAL_DOCS          = NO
+
+# If the CASE_SENSE_NAMES tag is set to NO then doxygen will only generate file
+# names in lower-case letters. If set to YES, upper-case letters are also
+# allowed. This is useful if you have classes or files whose names only differ
+# in case and if your file system supports case sensitive file names. Windows
+# and Mac users are advised to set this option to NO.
+# The default value is: system dependent.
+
+CASE_SENSE_NAMES       = NO
+
+# If the HIDE_SCOPE_NAMES tag is set to NO then doxygen will show members with
+# their full class and namespace scopes in the documentation. If set to YES, the
+# scope will be hidden.
+# The default value is: NO.
+
+HIDE_SCOPE_NAMES       = NO
+
+# If the HIDE_COMPOUND_REFERENCE tag is set to NO (default) then doxygen will
+# append additional text to a page's title, such as Class Reference. If set to
+# YES the compound reference will be hidden.
+# The default value is: NO.
+
+HIDE_COMPOUND_REFERENCE= NO
+
+# If the SHOW_INCLUDE_FILES tag is set to YES then doxygen will put a list of
+# the files that are included by a file in the documentation of that file.
+# The default value is: YES.
+
+SHOW_INCLUDE_FILES     = YES
+
+# If the SHOW_GROUPED_MEMB_INC tag is set to YES then Doxygen will add for each
+# grouped member an include statement to the documentation, telling the reader
+# which file to include in order to use the member.
+# The default value is: NO.
+
+SHOW_GROUPED_MEMB_INC  = NO
+
+# If the FORCE_LOCAL_INCLUDES tag is set to YES then doxygen will list include
+# files with double quotes in the documentation rather than with sharp brackets.
+# The default value is: NO.
+
+FORCE_LOCAL_INCLUDES   = NO
+
+# If the INLINE_INFO tag is set to YES then a tag [inline] is inserted in the
+# documentation for inline members.
+# The default value is: YES.
+
+INLINE_INFO            = YES
+
+# If the SORT_MEMBER_DOCS tag is set to YES then doxygen will sort the
+# (detailed) documentation of file and class members alphabetically by member
+# name. If set to NO, the members will appear in declaration order.
+# The default value is: YES.
+
+SORT_MEMBER_DOCS       = YES
+
+# If the SORT_BRIEF_DOCS tag is set to YES then doxygen will sort the brief
+# descriptions of file, namespace and class members alphabetically by member
+# name. If set to NO, the members will appear in declaration order. Note that
+# this will also influence the order of the classes in the class list.
+# The default value is: NO.
+
+SORT_BRIEF_DOCS        = NO
+
+# If the SORT_MEMBERS_CTORS_1ST tag is set to YES then doxygen will sort the
+# (brief and detailed) documentation of class members so that constructors and
+# destructors are listed first. If set to NO the constructors will appear in the
+# respective orders defined by SORT_BRIEF_DOCS and SORT_MEMBER_DOCS.
+# Note: If SORT_BRIEF_DOCS is set to NO this option is ignored for sorting brief
+# member documentation.
+# Note: If SORT_MEMBER_DOCS is set to NO this option is ignored for sorting
+# detailed member documentation.
+# The default value is: NO.
+
+SORT_MEMBERS_CTORS_1ST = NO
+
+# If the SORT_GROUP_NAMES tag is set to YES then doxygen will sort the hierarchy
+# of group names into alphabetical order. If set to NO the group names will
+# appear in their defined order.
+# The default value is: NO.
+
+SORT_GROUP_NAMES       = NO
+
+# If the SORT_BY_SCOPE_NAME tag is set to YES, the class list will be sorted by
+# fully-qualified names, including namespaces. If set to NO, the class list will
+# be sorted only by class name, not including the namespace part.
+# Note: This option is not very useful if HIDE_SCOPE_NAMES is set to YES.
+# Note: This option applies only to the class list, not to the alphabetical
+# list.
+# The default value is: NO.
+
+SORT_BY_SCOPE_NAME     = NO
+
+# If the STRICT_PROTO_MATCHING option is enabled and doxygen fails to do proper
+# type resolution of all parameters of a function it will reject a match between
+# the prototype and the implementation of a member function even if there is
+# only one candidate or it is obvious which candidate to choose by doing a
+# simple string match. By disabling STRICT_PROTO_MATCHING doxygen will still
+# accept a match between prototype and implementation in such cases.
+# The default value is: NO.
+
+STRICT_PROTO_MATCHING  = NO
+
+# The GENERATE_TODOLIST tag can be used to enable (YES) or disable (NO) the todo
+# list. This list is created by putting \todo commands in the documentation.
+# The default value is: YES.
+
+GENERATE_TODOLIST      = YES
+
+# The GENERATE_TESTLIST tag can be used to enable (YES) or disable (NO) the test
+# list. This list is created by putting \test commands in the documentation.
+# The default value is: YES.
+
+GENERATE_TESTLIST      = YES
+
+# The GENERATE_BUGLIST tag can be used to enable (YES) or disable (NO) the bug
+# list. This list is created by putting \bug commands in the documentation.
+# The default value is: YES.
+
+GENERATE_BUGLIST       = YES
+
+# The GENERATE_DEPRECATEDLIST tag can be used to enable (YES) or disable (NO)
+# the deprecated list. This list is created by putting \deprecated commands in
+# the documentation.
+# The default value is: YES.
+
+GENERATE_DEPRECATEDLIST= YES
+
+# The ENABLED_SECTIONS tag can be used to enable conditional documentation
+# sections, marked by \if <section_label> ... \endif and \cond <section_label>
+# ... \endcond blocks.
+
+ENABLED_SECTIONS       =
+
+# The MAX_INITIALIZER_LINES tag determines the maximum number of lines that the
+# initial value of a variable or macro / define can have for it to appear in the
+# documentation. If the initializer consists of more lines than specified here
+# it will be hidden. Use a value of 0 to hide initializers completely. The
+# appearance of the value of individual variables and macros / defines can be
+# controlled using \showinitializer or \hideinitializer command in the
+# documentation regardless of this setting.
+# Minimum value: 0, maximum value: 10000, default value: 30.
+
+MAX_INITIALIZER_LINES  = 30
+
+# Set the SHOW_USED_FILES tag to NO to disable the list of files generated at
+# the bottom of the documentation of classes and structs. If set to YES, the
+# list will mention the files that were used to generate the documentation.
+# The default value is: YES.
+
+SHOW_USED_FILES        = YES
+
+# Set the SHOW_FILES tag to NO to disable the generation of the Files page. This
+# will remove the Files entry from the Quick Index and from the Folder Tree View
+# (if specified).
+# The default value is: YES.
+
+SHOW_FILES             = YES
+
+# Set the SHOW_NAMESPACES tag to NO to disable the generation of the Namespaces
+# page. This will remove the Namespaces entry from the Quick Index and from the
+# Folder Tree View (if specified).
+# The default value is: YES.
+
+SHOW_NAMESPACES        = YES
+
+# The FILE_VERSION_FILTER tag can be used to specify a program or script that
+# doxygen should invoke to get the current version for each file (typically from
+# the version control system). Doxygen will invoke the program by executing (via
+# popen()) the command command input-file, where command is the value of the
+# FILE_VERSION_FILTER tag, and input-file is the name of an input file provided
+# by doxygen. Whatever the program writes to standard output is used as the file
+# version. For an example see the documentation.
+
+FILE_VERSION_FILTER    =
+
+# The LAYOUT_FILE tag can be used to specify a layout file which will be parsed
+# by doxygen. The layout file controls the global structure of the generated
+# output files in an output format independent way. To create the layout file
+# that represents doxygen's defaults, run doxygen with the -l option. You can
+# optionally specify a file name after the option, if omitted DoxygenLayout.xml
+# will be used as the name of the layout file.
+#
+# Note that if you run doxygen from a directory containing a file called
+# DoxygenLayout.xml, doxygen will parse it automatically even if the LAYOUT_FILE
+# tag is left empty.
+
+LAYOUT_FILE            =
+
+# The CITE_BIB_FILES tag can be used to specify one or more bib files containing
+# the reference definitions. This must be a list of .bib files. The .bib
+# extension is automatically appended if omitted. This requires the bibtex tool
+# to be installed. See also http://en.wikipedia.org/wiki/BibTeX for more info.
+# For LaTeX the style of the bibliography can be controlled using
+# LATEX_BIB_STYLE. To use this feature you need bibtex and perl available in the
+# search path. See also \cite for info how to create references.
+
+CITE_BIB_FILES         =
+
+#---------------------------------------------------------------------------
+# Configuration options related to warning and progress messages
+#---------------------------------------------------------------------------
+
+# The QUIET tag can be used to turn on/off the messages that are generated to
+# standard output by doxygen. If QUIET is set to YES this implies that the
+# messages are off.
+# The default value is: NO.
+
+QUIET                  = NO
+
+# The WARNINGS tag can be used to turn on/off the warning messages that are
+# generated to standard error (stderr) by doxygen. If WARNINGS is set to YES
+# this implies that the warnings are on.
+#
+# Tip: Turn warnings on while writing the documentation.
+# The default value is: YES.
+
+WARNINGS               = YES
+
+# If the WARN_IF_UNDOCUMENTED tag is set to YES then doxygen will generate
+# warnings for undocumented members. If EXTRACT_ALL is set to YES then this flag
+# will automatically be disabled.
+# The default value is: YES.
+
+WARN_IF_UNDOCUMENTED   = YES
+
+# If the WARN_IF_DOC_ERROR tag is set to YES, doxygen will generate warnings for
+# potential errors in the documentation, such as not documenting some parameters
+# in a documented function, or documenting parameters that don't exist or using
+# markup commands wrongly.
+# The default value is: YES.
+
+WARN_IF_DOC_ERROR      = YES
+
+# This WARN_NO_PARAMDOC option can be enabled to get warnings for functions that
+# are documented, but have no documentation for their parameters or return
+# value. If set to NO, doxygen will only warn about wrong or incomplete
+# parameter documentation, but not about the absence of documentation.
+# The default value is: NO.
+
+WARN_NO_PARAMDOC       = NO
+
+# If the WARN_AS_ERROR tag is set to YES then doxygen will immediately stop when
+# a warning is encountered.
+# The default value is: NO.
+
+WARN_AS_ERROR          = NO
+
+# The WARN_FORMAT tag determines the format of the warning messages that doxygen
+# can produce. The string should contain the $file, $line, and $text tags, which
+# will be replaced by the file and line number from which the warning originated
+# and the warning text. Optionally the format may contain $version, which will
+# be replaced by the version of the file (if it could be obtained via
+# FILE_VERSION_FILTER)
+# The default value is: $file:$line: $text.
+
+WARN_FORMAT            = "$file:$line: $text"
+
+# The WARN_LOGFILE tag can be used to specify a file to which warning and error
+# messages should be written. If left blank the output is written to standard
+# error (stderr).
+
+WARN_LOGFILE           =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the input files
+#---------------------------------------------------------------------------
+
+# The INPUT tag is used to specify the files and/or directories that contain
+# documented source files. You may enter file names like myfile.cpp or
+# directories like /usr/src/myproject. Separate the files or directories with
+# spaces. See also FILE_PATTERNS and EXTENSION_MAPPING
+# Note: If this tag is empty the current directory is searched.
+
+INPUT                  = td/generate/auto/td/telegram/td_api.h td/generate/auto/td/telegram/td_api.hpp td/tl/TlObject.h td/telegram/Client.h td/telegram/ClientActor.h td/telegram/Log.h td/telegram/TdCallback.h td/telegram/td_json_client.h td/telegram/td_log.h ./README.md
+
+# This tag can be used to specify the character encoding of the source files
+# that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses
+# libiconv (or the iconv built into libc) for the transcoding. See the libiconv
+# documentation (see: http://www.gnu.org/software/libiconv) for the list of
+# possible encodings.
+# The default value is: UTF-8.
+
+INPUT_ENCODING         = UTF-8
+
+# If the value of the INPUT tag contains directories, you can use the
+# FILE_PATTERNS tag to specify one or more wildcard patterns (like *.cpp and
+# *.h) to filter out the source-files in the directories.
+#
+# Note that for custom extensions or not directly supported extensions you also
+# need to set EXTENSION_MAPPING for the extension otherwise the files are not
+# read by doxygen.
+#
+# If left blank the following patterns are tested:*.c, *.cc, *.cxx, *.cpp,
+# *.c++, *.java, *.ii, *.ixx, *.ipp, *.i++, *.inl, *.idl, *.ddl, *.odl, *.h,
+# *.hh, *.hxx, *.hpp, *.h++, *.cs, *.d, *.php, *.php4, *.php5, *.phtml, *.inc,
+# *.m, *.markdown, *.md, *.mm, *.dox, *.py, *.pyw, *.f90, *.f95, *.f03, *.f08,
+# *.f, *.for, *.tcl, *.vhd, *.vhdl, *.ucf and *.qsf.
+
+FILE_PATTERNS          = *.c \
+                         *.cc \
+                         *.cxx \
+                         *.cpp \
+                         *.c++ \
+                         *.java \
+                         *.ii \
+                         *.ixx \
+                         *.ipp \
+                         *.i++ \
+                         *.inl \
+                         *.idl \
+                         *.ddl \
+                         *.odl \
+                         *.h \
+                         *.hh \
+                         *.hxx \
+                         *.hpp \
+                         *.h++ \
+                         *.cs \
+                         *.d \
+                         *.php \
+                         *.php4 \
+                         *.php5 \
+                         *.phtml \
+                         *.inc \
+                         *.m \
+                         *.markdown \
+                         *.md \
+                         *.mm \
+                         *.dox \
+                         *.py \
+                         *.pyw \
+                         *.f90 \
+                         *.f95 \
+                         *.f03 \
+                         *.f08 \
+                         *.f \
+                         *.for \
+                         *.tcl \
+                         *.vhd \
+                         *.vhdl \
+                         *.ucf \
+                         *.qsf
+
+# The RECURSIVE tag can be used to specify whether or not subdirectories should
+# be searched for input files as well.
+# The default value is: NO.
+
+RECURSIVE              = NO
+
+# The EXCLUDE tag can be used to specify files and/or directories that should be
+# excluded from the INPUT source files. This way you can easily exclude a
+# subdirectory from a directory tree whose root is specified with the INPUT tag.
+#
+# Note that relative paths are relative to the directory from which doxygen is
+# run.
+
+EXCLUDE                =
+
+# The EXCLUDE_SYMLINKS tag can be used to select whether or not files or
+# directories that are symbolic links (a Unix file system feature) are excluded
+# from the input.
+# The default value is: NO.
+
+EXCLUDE_SYMLINKS       = NO
+
+# If the value of the INPUT tag contains directories, you can use the
+# EXCLUDE_PATTERNS tag to specify one or more wildcard patterns to exclude
+# certain files from those directories.
+#
+# Note that the wildcards are matched against the file with absolute path, so to
+# exclude all test directories for example use the pattern */test/*
+
+EXCLUDE_PATTERNS       =
+
+# The EXCLUDE_SYMBOLS tag can be used to specify one or more symbol names
+# (namespaces, classes, functions, etc.) that should be excluded from the
+# output. The symbol name can be a fully qualified name, a word, or if the
+# wildcard * is used, a substring. Examples: ANamespace, AClass,
+# AClass::ANamespace, ANamespace::*Test
+#
+# Note that the wildcards are matched against the file with absolute path, so to
+# exclude all test directories use the pattern */test/*
+
+EXCLUDE_SYMBOLS        =
+
+# The EXAMPLE_PATH tag can be used to specify one or more files or directories
+# that contain example code fragments that are included (see the \include
+# command).
+
+EXAMPLE_PATH           =
+
+# If the value of the EXAMPLE_PATH tag contains directories, you can use the
+# EXAMPLE_PATTERNS tag to specify one or more wildcard pattern (like *.cpp and
+# *.h) to filter out the source-files in the directories. If left blank all
+# files are included.
+
+EXAMPLE_PATTERNS       = *
+
+# If the EXAMPLE_RECURSIVE tag is set to YES then subdirectories will be
+# searched for input files to be used with the \include or \dontinclude commands
+# irrespective of the value of the RECURSIVE tag.
+# The default value is: NO.
+
+EXAMPLE_RECURSIVE      = NO
+
+# The IMAGE_PATH tag can be used to specify one or more files or directories
+# that contain images that are to be included in the documentation (see the
+# \image command).
+
+IMAGE_PATH             =
+
+# The INPUT_FILTER tag can be used to specify a program that doxygen should
+# invoke to filter for each input file. Doxygen will invoke the filter program
+# by executing (via popen()) the command:
+#
+# <filter> <input-file>
+#
+# where <filter> is the value of the INPUT_FILTER tag, and <input-file> is the
+# name of an input file. Doxygen will then use the output that the filter
+# program writes to standard output. If FILTER_PATTERNS is specified, this tag
+# will be ignored.
+#
+# Note that the filter must not add or remove lines; it is applied before the
+# code is scanned, but not when the output code is generated. If lines are added
+# or removed, the anchors will not be placed correctly.
+#
+# Note that for custom extensions or not directly supported extensions you also
+# need to set EXTENSION_MAPPING for the extension otherwise the files are not
+# properly processed by doxygen.
+
+INPUT_FILTER           =
+
+# The FILTER_PATTERNS tag can be used to specify filters on a per file pattern
+# basis. Doxygen will compare the file name with each pattern and apply the
+# filter if there is a match. The filters are a list of the form: pattern=filter
+# (like *.cpp=my_cpp_filter). See INPUT_FILTER for further information on how
+# filters are used. If the FILTER_PATTERNS tag is empty or if none of the
+# patterns match the file name, INPUT_FILTER is applied.
+#
+# Note that for custom extensions or not directly supported extensions you also
+# need to set EXTENSION_MAPPING for the extension otherwise the files are not
+# properly processed by doxygen.
+
+FILTER_PATTERNS        =
+
+# If the FILTER_SOURCE_FILES tag is set to YES, the input filter (if set using
+# INPUT_FILTER) will also be used to filter the input files that are used for
+# producing the source files to browse (i.e. when SOURCE_BROWSER is set to YES).
+# The default value is: NO.
+
+FILTER_SOURCE_FILES    = NO
+
+# The FILTER_SOURCE_PATTERNS tag can be used to specify source filters per file
+# pattern. A pattern will override the setting for FILTER_PATTERN (if any) and
+# it is also possible to disable source filtering for a specific pattern using
+# *.ext= (so without naming a filter).
+# This tag requires that the tag FILTER_SOURCE_FILES is set to YES.
+
+FILTER_SOURCE_PATTERNS =
+
+# If the USE_MDFILE_AS_MAINPAGE tag refers to the name of a markdown file that
+# is part of the input, its contents will be placed on the main page
+# (index.html). This can be useful if you have a project on for instance GitHub
+# and want to reuse the introduction page also for the doxygen output.
+
+USE_MDFILE_AS_MAINPAGE = ./README.md
+
+#---------------------------------------------------------------------------
+# Configuration options related to source browsing
+#---------------------------------------------------------------------------
+
+# If the SOURCE_BROWSER tag is set to YES then a list of source files will be
+# generated. Documented entities will be cross-referenced with these sources.
+#
+# Note: To get rid of all source code in the generated output, make sure that
+# also VERBATIM_HEADERS is set to NO.
+# The default value is: NO.
+
+SOURCE_BROWSER         = NO
+
+# Setting the INLINE_SOURCES tag to YES will include the body of functions,
+# classes and enums directly into the documentation.
+# The default value is: NO.
+
+INLINE_SOURCES         = NO
+
+# Setting the STRIP_CODE_COMMENTS tag to YES will instruct doxygen to hide any
+# special comment blocks from generated source code fragments. Normal C, C++ and
+# Fortran comments will always remain visible.
+# The default value is: YES.
+
+STRIP_CODE_COMMENTS    = YES
+
+# If the REFERENCED_BY_RELATION tag is set to YES then for each documented
+# function all documented functions referencing it will be listed.
+# The default value is: NO.
+
+REFERENCED_BY_RELATION = NO
+
+# If the REFERENCES_RELATION tag is set to YES then for each documented function
+# all documented entities called/used by that function will be listed.
+# The default value is: NO.
+
+REFERENCES_RELATION    = NO
+
+# If the REFERENCES_LINK_SOURCE tag is set to YES and SOURCE_BROWSER tag is set
+# to YES then the hyperlinks from functions in REFERENCES_RELATION and
+# REFERENCED_BY_RELATION lists will link to the source code. Otherwise they will
+# link to the documentation.
+# The default value is: YES.
+
+REFERENCES_LINK_SOURCE = YES
+
+# If SOURCE_TOOLTIPS is enabled (the default) then hovering a hyperlink in the
+# source code will show a tooltip with additional information such as prototype,
+# brief description and links to the definition and documentation. Since this
+# will make the HTML file larger and loading of large files a bit slower, you
+# can opt to disable this feature.
+# The default value is: YES.
+# This tag requires that the tag SOURCE_BROWSER is set to YES.
+
+SOURCE_TOOLTIPS        = YES
+
+# If the USE_HTAGS tag is set to YES then the references to source code will
+# point to the HTML generated by the htags(1) tool instead of doxygen built-in
+# source browser. The htags tool is part of GNU's global source tagging system
+# (see http://www.gnu.org/software/global/global.html). You will need version
+# 4.8.6 or higher.
+#
+# To use it do the following:
+# - Install the latest version of global
+# - Enable SOURCE_BROWSER and USE_HTAGS in the config file
+# - Make sure the INPUT points to the root of the source tree
+# - Run doxygen as normal
+#
+# Doxygen will invoke htags (and that will in turn invoke gtags), so these
+# tools must be available from the command line (i.e. in the search path).
+#
+# The result: instead of the source browser generated by doxygen, the links to
+# source code will now point to the output of htags.
+# The default value is: NO.
+# This tag requires that the tag SOURCE_BROWSER is set to YES.
+
+USE_HTAGS              = NO
+
+# If the VERBATIM_HEADERS tag is set the YES then doxygen will generate a
+# verbatim copy of the header file for each class for which an include is
+# specified. Set to NO to disable this.
+# See also: Section \class.
+# The default value is: YES.
+
+VERBATIM_HEADERS       = YES
+
+#---------------------------------------------------------------------------
+# Configuration options related to the alphabetical class index
+#---------------------------------------------------------------------------
+
+# If the ALPHABETICAL_INDEX tag is set to YES, an alphabetical index of all
+# compounds will be generated. Enable this if the project contains a lot of
+# classes, structs, unions or interfaces.
+# The default value is: YES.
+
+ALPHABETICAL_INDEX     = YES
+
+# The COLS_IN_ALPHA_INDEX tag can be used to specify the number of columns in
+# which the alphabetical index list will be split.
+# Minimum value: 1, maximum value: 20, default value: 5.
+# This tag requires that the tag ALPHABETICAL_INDEX is set to YES.
+
+COLS_IN_ALPHA_INDEX    = 5
+
+# In case all classes in a project start with a common prefix, all classes will
+# be put under the same header in the alphabetical index. The IGNORE_PREFIX tag
+# can be used to specify a prefix (or a list of prefixes) that should be ignored
+# while generating the index headers.
+# This tag requires that the tag ALPHABETICAL_INDEX is set to YES.
+
+IGNORE_PREFIX          =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the HTML output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_HTML tag is set to YES, doxygen will generate HTML output
+# The default value is: YES.
+
+GENERATE_HTML          = YES
+
+# The HTML_OUTPUT tag is used to specify where the HTML docs will be put. If a
+# relative path is entered the value of OUTPUT_DIRECTORY will be put in front of
+# it.
+# The default directory is: html.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_OUTPUT            = html
+
+# The HTML_FILE_EXTENSION tag can be used to specify the file extension for each
+# generated HTML page (for example: .htm, .php, .asp).
+# The default value is: .html.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_FILE_EXTENSION    = .html
+
+# The HTML_HEADER tag can be used to specify a user-defined HTML header file for
+# each generated HTML page. If the tag is left blank doxygen will generate a
+# standard header.
+#
+# To get valid HTML the header file that includes any scripts and style sheets
+# that doxygen needs, which is dependent on the configuration options used (e.g.
+# the setting GENERATE_TREEVIEW). It is highly recommended to start with a
+# default header using
+# doxygen -w html new_header.html new_footer.html new_stylesheet.css
+# YourConfigFile
+# and then modify the file new_header.html. See also section "Doxygen usage"
+# for information on how to generate the default header that doxygen normally
+# uses.
+# Note: The header is subject to change so you typically have to regenerate the
+# default header when upgrading to a newer version of doxygen. For a description
+# of the possible markers and block names see the documentation.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_HEADER            =
+
+# The HTML_FOOTER tag can be used to specify a user-defined HTML footer for each
+# generated HTML page. If the tag is left blank doxygen will generate a standard
+# footer. See HTML_HEADER for more information on how to generate a default
+# footer and what special commands can be used inside the footer. See also
+# section "Doxygen usage" for information on how to generate the default footer
+# that doxygen normally uses.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_FOOTER            =
+
+# The HTML_STYLESHEET tag can be used to specify a user-defined cascading style
+# sheet that is used by each HTML page. It can be used to fine-tune the look of
+# the HTML output. If left blank doxygen will generate a default style sheet.
+# See also section "Doxygen usage" for information on how to generate the style
+# sheet that doxygen normally uses.
+# Note: It is recommended to use HTML_EXTRA_STYLESHEET instead of this tag, as
+# it is more robust and this tag (HTML_STYLESHEET) will in the future become
+# obsolete.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_STYLESHEET        =
+
+# The HTML_EXTRA_STYLESHEET tag can be used to specify additional user-defined
+# cascading style sheets that are included after the standard style sheets
+# created by doxygen. Using this option one can overrule certain style aspects.
+# This is preferred over using HTML_STYLESHEET since it does not replace the
+# standard style sheet and is therefore more robust against future updates.
+# Doxygen will copy the style sheet files to the output directory.
+# Note: The order of the extra style sheet files is of importance (e.g. the last
+# style sheet in the list overrules the setting of the previous ones in the
+# list). For an example see the documentation.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_EXTRA_STYLESHEET  =
+
+# The HTML_EXTRA_FILES tag can be used to specify one or more extra images or
+# other source files which should be copied to the HTML output directory. Note
+# that these files will be copied to the base HTML output directory. Use the
+# $relpath^ marker in the HTML_HEADER and/or HTML_FOOTER files to load these
+# files. In the HTML_STYLESHEET file, use the file name only. Also note that the
+# files will be copied as-is; there are no commands or markers available.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_EXTRA_FILES       =
+
+# The HTML_COLORSTYLE_HUE tag controls the color of the HTML output. Doxygen
+# will adjust the colors in the style sheet and background images according to
+# this color. Hue is specified as an angle on a colorwheel, see
+# http://en.wikipedia.org/wiki/Hue for more information. For instance the value
+# 0 represents red, 60 is yellow, 120 is green, 180 is cyan, 240 is blue, 300
+# purple, and 360 is red again.
+# Minimum value: 0, maximum value: 359, default value: 220.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_COLORSTYLE_HUE    = 220
+
+# The HTML_COLORSTYLE_SAT tag controls the purity (or saturation) of the colors
+# in the HTML output. For a value of 0 the output will use grayscales only. A
+# value of 255 will produce the most vivid colors.
+# Minimum value: 0, maximum value: 255, default value: 100.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_COLORSTYLE_SAT    = 100
+
+# The HTML_COLORSTYLE_GAMMA tag controls the gamma correction applied to the
+# luminance component of the colors in the HTML output. Values below 100
+# gradually make the output lighter, whereas values above 100 make the output
+# darker. The value divided by 100 is the actual gamma applied, so 80 represents
+# a gamma of 0.8, The value 220 represents a gamma of 2.2, and 100 does not
+# change the gamma.
+# Minimum value: 40, maximum value: 240, default value: 80.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_COLORSTYLE_GAMMA  = 80
+
+# If the HTML_TIMESTAMP tag is set to YES then the footer of each generated HTML
+# page will contain the date and time when the page was generated. Setting this
+# to YES can help to show when doxygen was last run and thus if the
+# documentation is up to date.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_TIMESTAMP         = NO
+
+# If the HTML_DYNAMIC_SECTIONS tag is set to YES then the generated HTML
+# documentation will contain sections that can be hidden and shown after the
+# page has loaded.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_DYNAMIC_SECTIONS  = NO
+
+# With HTML_INDEX_NUM_ENTRIES one can control the preferred number of entries
+# shown in the various tree structured indices initially; the user can expand
+# and collapse entries dynamically later on. Doxygen will expand the tree to
+# such a level that at most the specified number of entries are visible (unless
+# a fully collapsed tree already exceeds this amount). So setting the number of
+# entries 1 will produce a full collapsed tree by default. 0 is a special value
+# representing an infinite number of entries and will result in a full expanded
+# tree by default.
+# Minimum value: 0, maximum value: 9999, default value: 100.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_INDEX_NUM_ENTRIES = 100
+
+# If the GENERATE_DOCSET tag is set to YES, additional index files will be
+# generated that can be used as input for Apple's Xcode 3 integrated development
+# environment (see: http://developer.apple.com/tools/xcode/), introduced with
+# OSX 10.5 (Leopard). To create a documentation set, doxygen will generate a
+# Makefile in the HTML output directory. Running make will produce the docset in
+# that directory and running make install will install the docset in
+# ~/Library/Developer/Shared/Documentation/DocSets so that Xcode will find it at
+# startup. See http://developer.apple.com/tools/creatingdocsetswithdoxygen.html
+# for more information.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+GENERATE_DOCSET        = NO
+
+# This tag determines the name of the docset feed. A documentation feed provides
+# an umbrella under which multiple documentation sets from a single provider
+# (such as a company or product suite) can be grouped.
+# The default value is: Doxygen generated docs.
+# This tag requires that the tag GENERATE_DOCSET is set to YES.
+
+DOCSET_FEEDNAME        = "Doxygen generated docs"
+
+# This tag specifies a string that should uniquely identify the documentation
+# set bundle. This should be a reverse domain-name style string, e.g.
+# com.mycompany.MyDocSet. Doxygen will append .docset to the name.
+# The default value is: org.doxygen.Project.
+# This tag requires that the tag GENERATE_DOCSET is set to YES.
+
+DOCSET_BUNDLE_ID       = org.doxygen.Project
+
+# The DOCSET_PUBLISHER_ID tag specifies a string that should uniquely identify
+# the documentation publisher. This should be a reverse domain-name style
+# string, e.g. com.mycompany.MyDocSet.documentation.
+# The default value is: org.doxygen.Publisher.
+# This tag requires that the tag GENERATE_DOCSET is set to YES.
+
+DOCSET_PUBLISHER_ID    = org.doxygen.Publisher
+
+# The DOCSET_PUBLISHER_NAME tag identifies the documentation publisher.
+# The default value is: Publisher.
+# This tag requires that the tag GENERATE_DOCSET is set to YES.
+
+DOCSET_PUBLISHER_NAME  = Publisher
+
+# If the GENERATE_HTMLHELP tag is set to YES then doxygen generates three
+# additional HTML index files: index.hhp, index.hhc, and index.hhk. The
+# index.hhp is a project file that can be read by Microsoft's HTML Help Workshop
+# (see: http://www.microsoft.com/en-us/download/details.aspx?id=21138) on
+# Windows.
+#
+# The HTML Help Workshop contains a compiler that can convert all HTML output
+# generated by doxygen into a single compiled HTML file (.chm). Compiled HTML
+# files are now used as the Windows 98 help format, and will replace the old
+# Windows help format (.hlp) on all Windows platforms in the future. Compressed
+# HTML files also contain an index, a table of contents, and you can search for
+# words in the documentation. The HTML workshop also contains a viewer for
+# compressed HTML files.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+GENERATE_HTMLHELP      = NO
+
+# The CHM_FILE tag can be used to specify the file name of the resulting .chm
+# file. You can add a path in front of the file if the result should not be
+# written to the html output directory.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+CHM_FILE               =
+
+# The HHC_LOCATION tag can be used to specify the location (absolute path
+# including file name) of the HTML help compiler (hhc.exe). If non-empty,
+# doxygen will try to run the HTML help compiler on the generated index.hhp.
+# The file has to be specified with full path.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+HHC_LOCATION           =
+
+# The GENERATE_CHI flag controls if a separate .chi index file is generated
+# (YES) or that it should be included in the master .chm file (NO).
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+GENERATE_CHI           = NO
+
+# The CHM_INDEX_ENCODING is used to encode HtmlHelp index (hhk), content (hhc)
+# and project file content.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+CHM_INDEX_ENCODING     =
+
+# The BINARY_TOC flag controls whether a binary table of contents is generated
+# (YES) or a normal table of contents (NO) in the .chm file. Furthermore it
+# enables the Previous and Next buttons.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+BINARY_TOC             = NO
+
+# The TOC_EXPAND flag can be set to YES to add extra items for group members to
+# the table of contents of the HTML help documentation and to the tree view.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+TOC_EXPAND             = NO
+
+# If the GENERATE_QHP tag is set to YES and both QHP_NAMESPACE and
+# QHP_VIRTUAL_FOLDER are set, an additional index file will be generated that
+# can be used as input for Qt's qhelpgenerator to generate a Qt Compressed Help
+# (.qch) of the generated HTML documentation.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+GENERATE_QHP           = NO
+
+# If the QHG_LOCATION tag is specified, the QCH_FILE tag can be used to specify
+# the file name of the resulting .qch file. The path specified is relative to
+# the HTML output folder.
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QCH_FILE               =
+
+# The QHP_NAMESPACE tag specifies the namespace to use when generating Qt Help
+# Project output. For more information please see Qt Help Project / Namespace
+# (see: http://qt-project.org/doc/qt-4.8/qthelpproject.html#namespace).
+# The default value is: org.doxygen.Project.
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHP_NAMESPACE          = org.doxygen.Project
+
+# The QHP_VIRTUAL_FOLDER tag specifies the namespace to use when generating Qt
+# Help Project output. For more information please see Qt Help Project / Virtual
+# Folders (see: http://qt-project.org/doc/qt-4.8/qthelpproject.html#virtual-
+# folders).
+# The default value is: doc.
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHP_VIRTUAL_FOLDER     = doc
+
+# If the QHP_CUST_FILTER_NAME tag is set, it specifies the name of a custom
+# filter to add. For more information please see Qt Help Project / Custom
+# Filters (see: http://qt-project.org/doc/qt-4.8/qthelpproject.html#custom-
+# filters).
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHP_CUST_FILTER_NAME   =
+
+# The QHP_CUST_FILTER_ATTRS tag specifies the list of the attributes of the
+# custom filter to add. For more information please see Qt Help Project / Custom
+# Filters (see: http://qt-project.org/doc/qt-4.8/qthelpproject.html#custom-
+# filters).
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHP_CUST_FILTER_ATTRS  =
+
+# The QHP_SECT_FILTER_ATTRS tag specifies the list of the attributes this
+# project's filter section matches. Qt Help Project / Filter Attributes (see:
+# http://qt-project.org/doc/qt-4.8/qthelpproject.html#filter-attributes).
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHP_SECT_FILTER_ATTRS  =
+
+# The QHG_LOCATION tag can be used to specify the location of Qt's
+# qhelpgenerator. If non-empty doxygen will try to run qhelpgenerator on the
+# generated .qhp file.
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHG_LOCATION           =
+
+# If the GENERATE_ECLIPSEHELP tag is set to YES, additional index files will be
+# generated, together with the HTML files, they form an Eclipse help plugin. To
+# install this plugin and make it available under the help contents menu in
+# Eclipse, the contents of the directory containing the HTML and XML files needs
+# to be copied into the plugins directory of eclipse. The name of the directory
+# within the plugins directory should be the same as the ECLIPSE_DOC_ID value.
+# After copying Eclipse needs to be restarted before the help appears.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+GENERATE_ECLIPSEHELP   = NO
+
+# A unique identifier for the Eclipse help plugin. When installing the plugin
+# the directory name containing the HTML and XML files should also have this
+# name. Each documentation set should have its own identifier.
+# The default value is: org.doxygen.Project.
+# This tag requires that the tag GENERATE_ECLIPSEHELP is set to YES.
+
+ECLIPSE_DOC_ID         = org.doxygen.Project
+
+# If you want full control over the layout of the generated HTML pages it might
+# be necessary to disable the index and replace it with your own. The
+# DISABLE_INDEX tag can be used to turn on/off the condensed index (tabs) at top
+# of each HTML page. A value of NO enables the index and the value YES disables
+# it. Since the tabs in the index contain the same information as the navigation
+# tree, you can set this option to YES if you also set GENERATE_TREEVIEW to YES.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+DISABLE_INDEX          = NO
+
+# The GENERATE_TREEVIEW tag is used to specify whether a tree-like index
+# structure should be generated to display hierarchical information. If the tag
+# value is set to YES, a side panel will be generated containing a tree-like
+# index structure (just like the one that is generated for HTML Help). For this
+# to work a browser that supports JavaScript, DHTML, CSS and frames is required
+# (i.e. any modern browser). Windows users are probably better off using the
+# HTML help feature. Via custom style sheets (see HTML_EXTRA_STYLESHEET) one can
+# further fine-tune the look of the index. As an example, the default style
+# sheet generated by doxygen has an example that shows how to put an image at
+# the root of the tree instead of the PROJECT_NAME. Since the tree basically has
+# the same information as the tab index, you could consider setting
+# DISABLE_INDEX to YES when enabling this option.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+GENERATE_TREEVIEW      = NO
+
+# The ENUM_VALUES_PER_LINE tag can be used to set the number of enum values that
+# doxygen will group on one line in the generated HTML documentation.
+#
+# Note that a value of 0 will completely suppress the enum values from appearing
+# in the overview section.
+# Minimum value: 0, maximum value: 20, default value: 4.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+ENUM_VALUES_PER_LINE   = 4
+
+# If the treeview is enabled (see GENERATE_TREEVIEW) then this tag can be used
+# to set the initial width (in pixels) of the frame in which the tree is shown.
+# Minimum value: 0, maximum value: 1500, default value: 250.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+TREEVIEW_WIDTH         = 250
+
+# If the EXT_LINKS_IN_WINDOW option is set to YES, doxygen will open links to
+# external symbols imported via tag files in a separate window.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+EXT_LINKS_IN_WINDOW    = NO
+
+# Use this tag to change the font size of LaTeX formulas included as images in
+# the HTML documentation. When you change the font size after a successful
+# doxygen run you need to manually remove any form_*.png images from the HTML
+# output directory to force them to be regenerated.
+# Minimum value: 8, maximum value: 50, default value: 10.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+FORMULA_FONTSIZE       = 10
+
+# Use the FORMULA_TRANPARENT tag to determine whether or not the images
+# generated for formulas are transparent PNGs. Transparent PNGs are not
+# supported properly for IE 6.0, but are supported on all modern browsers.
+#
+# Note that when changing this option you need to delete any form_*.png files in
+# the HTML output directory before the changes have effect.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+FORMULA_TRANSPARENT    = YES
+
+# Enable the USE_MATHJAX option to render LaTeX formulas using MathJax (see
+# http://www.mathjax.org) which uses client side Javascript for the rendering
+# instead of using pre-rendered bitmaps. Use this if you do not have LaTeX
+# installed or if you want to formulas look prettier in the HTML output. When
+# enabled you may also need to install MathJax separately and configure the path
+# to it using the MATHJAX_RELPATH option.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+USE_MATHJAX            = NO
+
+# When MathJax is enabled you can set the default output format to be used for
+# the MathJax output. See the MathJax site (see:
+# http://docs.mathjax.org/en/latest/output.html) for more details.
+# Possible values are: HTML-CSS (which is slower, but has the best
+# compatibility), NativeMML (i.e. MathML) and SVG.
+# The default value is: HTML-CSS.
+# This tag requires that the tag USE_MATHJAX is set to YES.
+
+MATHJAX_FORMAT         = HTML-CSS
+
+# When MathJax is enabled you need to specify the location relative to the HTML
+# output directory using the MATHJAX_RELPATH option. The destination directory
+# should contain the MathJax.js script. For instance, if the mathjax directory
+# is located at the same level as the HTML output directory, then
+# MATHJAX_RELPATH should be ../mathjax. The default value points to the MathJax
+# Content Delivery Network so you can quickly see the result without installing
+# MathJax. However, it is strongly recommended to install a local copy of
+# MathJax from http://www.mathjax.org before deployment.
+# The default value is: http://cdn.mathjax.org/mathjax/latest.
+# This tag requires that the tag USE_MATHJAX is set to YES.
+
+MATHJAX_RELPATH        = http://cdn.mathjax.org/mathjax/latest
+
+# The MATHJAX_EXTENSIONS tag can be used to specify one or more MathJax
+# extension names that should be enabled during MathJax rendering. For example
+# MATHJAX_EXTENSIONS = TeX/AMSmath TeX/AMSsymbols
+# This tag requires that the tag USE_MATHJAX is set to YES.
+
+MATHJAX_EXTENSIONS     =
+
+# The MATHJAX_CODEFILE tag can be used to specify a file with javascript pieces
+# of code that will be used on startup of the MathJax code. See the MathJax site
+# (see: http://docs.mathjax.org/en/latest/output.html) for more details. For an
+# example see the documentation.
+# This tag requires that the tag USE_MATHJAX is set to YES.
+
+MATHJAX_CODEFILE       =
+
+# When the SEARCHENGINE tag is enabled doxygen will generate a search box for
+# the HTML output. The underlying search engine uses javascript and DHTML and
+# should work on any modern browser. Note that when using HTML help
+# (GENERATE_HTMLHELP), Qt help (GENERATE_QHP), or docsets (GENERATE_DOCSET)
+# there is already a search function so this one should typically be disabled.
+# For large projects the javascript based search engine can be slow, then
+# enabling SERVER_BASED_SEARCH may provide a better solution. It is possible to
+# search using the keyboard; to jump to the search box use <access key> + S
+# (what the <access key> is depends on the OS and browser, but it is typically
+# <CTRL>, <ALT>/<option>, or both). Inside the search box use the <cursor down
+# key> to jump into the search results window, the results can be navigated
+# using the <cursor keys>. Press <Enter> to select an item or <escape> to cancel
+# the search. The filter options can be selected when the cursor is inside the
+# search box by pressing <Shift>+<cursor down>. Also here use the <cursor keys>
+# to select a filter and <Enter> or <escape> to activate or cancel the filter
+# option.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+SEARCHENGINE           = YES
+
+# When the SERVER_BASED_SEARCH tag is enabled the search engine will be
+# implemented using a web server instead of a web client using Javascript. There
+# are two flavors of web server based searching depending on the EXTERNAL_SEARCH
+# setting. When disabled, doxygen will generate a PHP script for searching and
+# an index file used by the script. When EXTERNAL_SEARCH is enabled the indexing
+# and searching needs to be provided by external tools. See the section
+# "External Indexing and Searching" for details.
+# The default value is: NO.
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+SERVER_BASED_SEARCH    = NO
+
+# When EXTERNAL_SEARCH tag is enabled doxygen will no longer generate the PHP
+# script for searching. Instead the search results are written to an XML file
+# which needs to be processed by an external indexer. Doxygen will invoke an
+# external search engine pointed to by the SEARCHENGINE_URL option to obtain the
+# search results.
+#
+# Doxygen ships with an example indexer (doxyindexer) and search engine
+# (doxysearch.cgi) which are based on the open source search engine library
+# Xapian (see: http://xapian.org/).
+#
+# See the section "External Indexing and Searching" for details.
+# The default value is: NO.
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+EXTERNAL_SEARCH        = NO
+
+# The SEARCHENGINE_URL should point to a search engine hosted by a web server
+# which will return the search results when EXTERNAL_SEARCH is enabled.
+#
+# Doxygen ships with an example indexer (doxyindexer) and search engine
+# (doxysearch.cgi) which are based on the open source search engine library
+# Xapian (see: http://xapian.org/). See the section "External Indexing and
+# Searching" for details.
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+SEARCHENGINE_URL       =
+
+# When SERVER_BASED_SEARCH and EXTERNAL_SEARCH are both enabled the unindexed
+# search data is written to a file for indexing by an external tool. With the
+# SEARCHDATA_FILE tag the name of this file can be specified.
+# The default file is: searchdata.xml.
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+SEARCHDATA_FILE        = searchdata.xml
+
+# When SERVER_BASED_SEARCH and EXTERNAL_SEARCH are both enabled the
+# EXTERNAL_SEARCH_ID tag can be used as an identifier for the project. This is
+# useful in combination with EXTRA_SEARCH_MAPPINGS to search through multiple
+# projects and redirect the results back to the right project.
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+EXTERNAL_SEARCH_ID     =
+
+# The EXTRA_SEARCH_MAPPINGS tag can be used to enable searching through doxygen
+# projects other than the one defined by this configuration file, but that are
+# all added to the same external search index. Each project needs to have a
+# unique id set via EXTERNAL_SEARCH_ID. The search mapping then maps the id of
+# to a relative location where the documentation can be found. The format is:
+# EXTRA_SEARCH_MAPPINGS = tagname1=loc1 tagname2=loc2 ...
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+EXTRA_SEARCH_MAPPINGS  =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the LaTeX output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_LATEX tag is set to YES, doxygen will generate LaTeX output.
+# The default value is: YES.
+
+GENERATE_LATEX         = NO
+
+# The LATEX_OUTPUT tag is used to specify where the LaTeX docs will be put. If a
+# relative path is entered the value of OUTPUT_DIRECTORY will be put in front of
+# it.
+# The default directory is: latex.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_OUTPUT           = latex
+
+# The LATEX_CMD_NAME tag can be used to specify the LaTeX command name to be
+# invoked.
+#
+# Note that when enabling USE_PDFLATEX this option is only used for generating
+# bitmaps for formulas in the HTML output, but not in the Makefile that is
+# written to the output directory.
+# The default file is: latex.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_CMD_NAME         = latex
+
+# The MAKEINDEX_CMD_NAME tag can be used to specify the command name to generate
+# index for LaTeX.
+# The default file is: makeindex.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+MAKEINDEX_CMD_NAME     = makeindex
+
+# If the COMPACT_LATEX tag is set to YES, doxygen generates more compact LaTeX
+# documents. This may be useful for small projects and may help to save some
+# trees in general.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+COMPACT_LATEX          = NO
+
+# The PAPER_TYPE tag can be used to set the paper type that is used by the
+# printer.
+# Possible values are: a4 (210 x 297 mm), letter (8.5 x 11 inches), legal (8.5 x
+# 14 inches) and executive (7.25 x 10.5 inches).
+# The default value is: a4.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+PAPER_TYPE             = a4
+
+# The EXTRA_PACKAGES tag can be used to specify one or more LaTeX package names
+# that should be included in the LaTeX output. The package can be specified just
+# by its name or with the correct syntax as to be used with the LaTeX
+# \usepackage command. To get the times font for instance you can specify :
+# EXTRA_PACKAGES=times or EXTRA_PACKAGES={times}
+# To use the option intlimits with the amsmath package you can specify:
+# EXTRA_PACKAGES=[intlimits]{amsmath}
+# If left blank no extra packages will be included.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+EXTRA_PACKAGES         =
+
+# The LATEX_HEADER tag can be used to specify a personal LaTeX header for the
+# generated LaTeX document. The header should contain everything until the first
+# chapter. If it is left blank doxygen will generate a standard header. See
+# section "Doxygen usage" for information on how to let doxygen write the
+# default header to a separate file.
+#
+# Note: Only use a user-defined header if you know what you are doing! The
+# following commands have a special meaning inside the header: $title,
+# $datetime, $date, $doxygenversion, $projectname, $projectnumber,
+# $projectbrief, $projectlogo. Doxygen will replace $title with the empty
+# string, for the replacement values of the other commands the user is referred
+# to HTML_HEADER.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_HEADER           =
+
+# The LATEX_FOOTER tag can be used to specify a personal LaTeX footer for the
+# generated LaTeX document. The footer should contain everything after the last
+# chapter. If it is left blank doxygen will generate a standard footer. See
+# LATEX_HEADER for more information on how to generate a default footer and what
+# special commands can be used inside the footer.
+#
+# Note: Only use a user-defined footer if you know what you are doing!
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_FOOTER           =
+
+# The LATEX_EXTRA_STYLESHEET tag can be used to specify additional user-defined
+# LaTeX style sheets that are included after the standard style sheets created
+# by doxygen. Using this option one can overrule certain style aspects. Doxygen
+# will copy the style sheet files to the output directory.
+# Note: The order of the extra style sheet files is of importance (e.g. the last
+# style sheet in the list overrules the setting of the previous ones in the
+# list).
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_EXTRA_STYLESHEET =
+
+# The LATEX_EXTRA_FILES tag can be used to specify one or more extra images or
+# other source files which should be copied to the LATEX_OUTPUT output
+# directory. Note that the files will be copied as-is; there are no commands or
+# markers available.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_EXTRA_FILES      =
+
+# If the PDF_HYPERLINKS tag is set to YES, the LaTeX that is generated is
+# prepared for conversion to PDF (using ps2pdf or pdflatex). The PDF file will
+# contain links (just like the HTML output) instead of page references. This
+# makes the output suitable for online browsing using a PDF viewer.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+PDF_HYPERLINKS         = YES
+
+# If the USE_PDFLATEX tag is set to YES, doxygen will use pdflatex to generate
+# the PDF file directly from the LaTeX files. Set this option to YES, to get a
+# higher quality PDF documentation.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+USE_PDFLATEX           = YES
+
+# If the LATEX_BATCHMODE tag is set to YES, doxygen will add the \batchmode
+# command to the generated LaTeX files. This will instruct LaTeX to keep running
+# if errors occur, instead of asking the user for help. This option is also used
+# when generating formulas in HTML.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_BATCHMODE        = NO
+
+# If the LATEX_HIDE_INDICES tag is set to YES then doxygen will not include the
+# index chapters (such as File Index, Compound Index, etc.) in the output.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_HIDE_INDICES     = NO
+
+# If the LATEX_SOURCE_CODE tag is set to YES then doxygen will include source
+# code with syntax highlighting in the LaTeX output.
+#
+# Note that which sources are shown also depends on other settings such as
+# SOURCE_BROWSER.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_SOURCE_CODE      = NO
+
+# The LATEX_BIB_STYLE tag can be used to specify the style to use for the
+# bibliography, e.g. plainnat, or ieeetr. See
+# http://en.wikipedia.org/wiki/BibTeX and \cite for more info.
+# The default value is: plain.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_BIB_STYLE        = plain
+
+# If the LATEX_TIMESTAMP tag is set to YES then the footer of each generated
+# page will contain the date and time when the page was generated. Setting this
+# to NO can help when comparing the output of multiple runs.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_TIMESTAMP        = NO
+
+#---------------------------------------------------------------------------
+# Configuration options related to the RTF output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_RTF tag is set to YES, doxygen will generate RTF output. The
+# RTF output is optimized for Word 97 and may not look too pretty with other RTF
+# readers/editors.
+# The default value is: NO.
+
+GENERATE_RTF           = NO
+
+# The RTF_OUTPUT tag is used to specify where the RTF docs will be put. If a
+# relative path is entered the value of OUTPUT_DIRECTORY will be put in front of
+# it.
+# The default directory is: rtf.
+# This tag requires that the tag GENERATE_RTF is set to YES.
+
+RTF_OUTPUT             = rtf
+
+# If the COMPACT_RTF tag is set to YES, doxygen generates more compact RTF
+# documents. This may be useful for small projects and may help to save some
+# trees in general.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_RTF is set to YES.
+
+COMPACT_RTF            = NO
+
+# If the RTF_HYPERLINKS tag is set to YES, the RTF that is generated will
+# contain hyperlink fields. The RTF file will contain links (just like the HTML
+# output) instead of page references. This makes the output suitable for online
+# browsing using Word or some other Word compatible readers that support those
+# fields.
+#
+# Note: WordPad (write) and others do not support links.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_RTF is set to YES.
+
+RTF_HYPERLINKS         = NO
+
+# Load stylesheet definitions from file. Syntax is similar to doxygen's config
+# file, i.e. a series of assignments. You only have to provide replacements,
+# missing definitions are set to their default value.
+#
+# See also section "Doxygen usage" for information on how to generate the
+# default style sheet that doxygen normally uses.
+# This tag requires that the tag GENERATE_RTF is set to YES.
+
+RTF_STYLESHEET_FILE    =
+
+# Set optional variables used in the generation of an RTF document. Syntax is
+# similar to doxygen's config file. A template extensions file can be generated
+# using doxygen -e rtf extensionFile.
+# This tag requires that the tag GENERATE_RTF is set to YES.
+
+RTF_EXTENSIONS_FILE    =
+
+# If the RTF_SOURCE_CODE tag is set to YES then doxygen will include source code
+# with syntax highlighting in the RTF output.
+#
+# Note that which sources are shown also depends on other settings such as
+# SOURCE_BROWSER.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_RTF is set to YES.
+
+RTF_SOURCE_CODE        = NO
+
+#---------------------------------------------------------------------------
+# Configuration options related to the man page output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_MAN tag is set to YES, doxygen will generate man pages for
+# classes and files.
+# The default value is: NO.
+
+GENERATE_MAN           = NO
+
+# The MAN_OUTPUT tag is used to specify where the man pages will be put. If a
+# relative path is entered the value of OUTPUT_DIRECTORY will be put in front of
+# it. A directory man3 will be created inside the directory specified by
+# MAN_OUTPUT.
+# The default directory is: man.
+# This tag requires that the tag GENERATE_MAN is set to YES.
+
+MAN_OUTPUT             = man
+
+# The MAN_EXTENSION tag determines the extension that is added to the generated
+# man pages. In case the manual section does not start with a number, the number
+# 3 is prepended. The dot (.) at the beginning of the MAN_EXTENSION tag is
+# optional.
+# The default value is: .3.
+# This tag requires that the tag GENERATE_MAN is set to YES.
+
+MAN_EXTENSION          = .3
+
+# The MAN_SUBDIR tag determines the name of the directory created within
+# MAN_OUTPUT in which the man pages are placed. If defaults to man followed by
+# MAN_EXTENSION with the initial . removed.
+# This tag requires that the tag GENERATE_MAN is set to YES.
+
+MAN_SUBDIR             =
+
+# If the MAN_LINKS tag is set to YES and doxygen generates man output, then it
+# will generate one additional man file for each entity documented in the real
+# man page(s). These additional files only source the real man page, but without
+# them the man command would be unable to find the correct page.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_MAN is set to YES.
+
+MAN_LINKS              = NO
+
+#---------------------------------------------------------------------------
+# Configuration options related to the XML output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_XML tag is set to YES, doxygen will generate an XML file that
+# captures the structure of the code including all documentation.
+# The default value is: NO.
+
+GENERATE_XML           = NO
+
+# The XML_OUTPUT tag is used to specify where the XML pages will be put. If a
+# relative path is entered the value of OUTPUT_DIRECTORY will be put in front of
+# it.
+# The default directory is: xml.
+# This tag requires that the tag GENERATE_XML is set to YES.
+
+XML_OUTPUT             = xml
+
+# If the XML_PROGRAMLISTING tag is set to YES, doxygen will dump the program
+# listings (including syntax highlighting and cross-referencing information) to
+# the XML output. Note that enabling this will significantly increase the size
+# of the XML output.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_XML is set to YES.
+
+XML_PROGRAMLISTING     = YES
+
+#---------------------------------------------------------------------------
+# Configuration options related to the DOCBOOK output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_DOCBOOK tag is set to YES, doxygen will generate Docbook files
+# that can be used to generate PDF.
+# The default value is: NO.
+
+GENERATE_DOCBOOK       = NO
+
+# The DOCBOOK_OUTPUT tag is used to specify where the Docbook pages will be put.
+# If a relative path is entered the value of OUTPUT_DIRECTORY will be put in
+# front of it.
+# The default directory is: docbook.
+# This tag requires that the tag GENERATE_DOCBOOK is set to YES.
+
+DOCBOOK_OUTPUT         = docbook
+
+# If the DOCBOOK_PROGRAMLISTING tag is set to YES, doxygen will include the
+# program listings (including syntax highlighting and cross-referencing
+# information) to the DOCBOOK output. Note that enabling this will significantly
+# increase the size of the DOCBOOK output.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_DOCBOOK is set to YES.
+
+DOCBOOK_PROGRAMLISTING = NO
+
+#---------------------------------------------------------------------------
+# Configuration options for the AutoGen Definitions output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_AUTOGEN_DEF tag is set to YES, doxygen will generate an
+# AutoGen Definitions (see http://autogen.sf.net) file that captures the
+# structure of the code including all documentation. Note that this feature is
+# still experimental and incomplete at the moment.
+# The default value is: NO.
+
+GENERATE_AUTOGEN_DEF   = NO
+
+#---------------------------------------------------------------------------
+# Configuration options related to the Perl module output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_PERLMOD tag is set to YES, doxygen will generate a Perl module
+# file that captures the structure of the code including all documentation.
+#
+# Note that this feature is still experimental and incomplete at the moment.
+# The default value is: NO.
+
+GENERATE_PERLMOD       = NO
+
+# If the PERLMOD_LATEX tag is set to YES, doxygen will generate the necessary
+# Makefile rules, Perl scripts and LaTeX code to be able to generate PDF and DVI
+# output from the Perl module output.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_PERLMOD is set to YES.
+
+PERLMOD_LATEX          = NO
+
+# If the PERLMOD_PRETTY tag is set to YES, the Perl module output will be nicely
+# formatted so it can be parsed by a human reader. This is useful if you want to
+# understand what is going on. On the other hand, if this tag is set to NO, the
+# size of the Perl module output will be much smaller and Perl will parse it
+# just the same.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_PERLMOD is set to YES.
+
+PERLMOD_PRETTY         = YES
+
+# The names of the make variables in the generated doxyrules.make file are
+# prefixed with the string contained in PERLMOD_MAKEVAR_PREFIX. This is useful
+# so different doxyrules.make files included by the same Makefile don't
+# overwrite each other's variables.
+# This tag requires that the tag GENERATE_PERLMOD is set to YES.
+
+PERLMOD_MAKEVAR_PREFIX =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the preprocessor
+#---------------------------------------------------------------------------
+
+# If the ENABLE_PREPROCESSING tag is set to YES, doxygen will evaluate all
+# C-preprocessor directives found in the sources and include files.
+# The default value is: YES.
+
+ENABLE_PREPROCESSING   = YES
+
+# If the MACRO_EXPANSION tag is set to YES, doxygen will expand all macro names
+# in the source code. If set to NO, only conditional compilation will be
+# performed. Macro expansion can be done in a controlled way by setting
+# EXPAND_ONLY_PREDEF to YES.
+# The default value is: NO.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+MACRO_EXPANSION        = YES
+
+# If the EXPAND_ONLY_PREDEF and MACRO_EXPANSION tags are both set to YES then
+# the macro expansion is limited to the macros specified with the PREDEFINED and
+# EXPAND_AS_DEFINED tags.
+# The default value is: NO.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+EXPAND_ONLY_PREDEF     = YES
+
+# If the SEARCH_INCLUDES tag is set to YES, the include files in the
+# INCLUDE_PATH will be searched if a #include is found.
+# The default value is: YES.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+SEARCH_INCLUDES        = YES
+
+# The INCLUDE_PATH tag can be used to specify one or more directories that
+# contain include files that are not input files but should be processed by the
+# preprocessor.
+# This tag requires that the tag SEARCH_INCLUDES is set to YES.
+
+INCLUDE_PATH           =
+
+# You can use the INCLUDE_FILE_PATTERNS tag to specify one or more wildcard
+# patterns (like *.h and *.hpp) to filter out the header-files in the
+# directories. If left blank, the patterns specified with FILE_PATTERNS will be
+# used.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+INCLUDE_FILE_PATTERNS  =
+
+# The PREDEFINED tag can be used to specify one or more macro names that are
+# defined before the preprocessor is started (similar to the -D option of e.g.
+# gcc). The argument of the tag is a list of macros of the form: name or
+# name=definition (no spaces). If the definition and the "=" are omitted, "=1"
+# is assumed. To prevent a macro definition from being undefined via #undef or
+# recursively expanded use the := operator instead of the = operator.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+PREDEFINED             =  TDJSON_EXPORT=
+
+# If the MACRO_EXPANSION and EXPAND_ONLY_PREDEF tags are set to YES then this
+# tag can be used to specify a list of macro names that should be expanded. The
+# macro definition that is found in the sources will be used. Use the PREDEFINED
+# tag if you want to use a different macro definition that overrules the
+# definition found in the source code.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+EXPAND_AS_DEFINED      =
+
+# If the SKIP_FUNCTION_MACROS tag is set to YES then doxygen's preprocessor will
+# remove all references to function-like macros that are alone on a line, have
+# an all uppercase name, and do not end with a semicolon. Such function macros
+# are typically used for boiler-plate code, and will confuse the parser if not
+# removed.
+# The default value is: YES.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+SKIP_FUNCTION_MACROS   = YES
+
+#---------------------------------------------------------------------------
+# Configuration options related to external references
+#---------------------------------------------------------------------------
+
+# The TAGFILES tag can be used to specify one or more tag files. For each tag
+# file the location of the external documentation should be added. The format of
+# a tag file without this location is as follows:
+# TAGFILES = file1 file2 ...
+# Adding location for the tag files is done as follows:
+# TAGFILES = file1=loc1 "file2 = loc2" ...
+# where loc1 and loc2 can be relative or absolute paths or URLs. See the
+# section "Linking to external documentation" for more information about the use
+# of tag files.
+# Note: Each tag file must have a unique name (where the name does NOT include
+# the path). If a tag file is not located in the directory in which doxygen is
+# run, you must also specify the path to the tagfile here.
+
+TAGFILES               =
+
+# When a file name is specified after GENERATE_TAGFILE, doxygen will create a
+# tag file that is based on the input files it reads. See section "Linking to
+# external documentation" for more information about the usage of tag files.
+
+GENERATE_TAGFILE       =
+
+# If the ALLEXTERNALS tag is set to YES, all external class will be listed in
+# the class index. If set to NO, only the inherited external classes will be
+# listed.
+# The default value is: NO.
+
+ALLEXTERNALS           = NO
+
+# If the EXTERNAL_GROUPS tag is set to YES, all external groups will be listed
+# in the modules index. If set to NO, only the current project's groups will be
+# listed.
+# The default value is: YES.
+
+EXTERNAL_GROUPS        = YES
+
+# If the EXTERNAL_PAGES tag is set to YES, all external pages will be listed in
+# the related pages index. If set to NO, only the current project's pages will
+# be listed.
+# The default value is: YES.
+
+EXTERNAL_PAGES         = YES
+
+# The PERL_PATH should be the absolute path and name of the perl script
+# interpreter (i.e. the result of 'which perl').
+# The default file (with absolute path) is: /usr/bin/perl.
+
+PERL_PATH              = /usr/bin/perl
+
+#---------------------------------------------------------------------------
+# Configuration options related to the dot tool
+#---------------------------------------------------------------------------
+
+# If the CLASS_DIAGRAMS tag is set to YES, doxygen will generate a class diagram
+# (in HTML and LaTeX) for classes with base or super classes. Setting the tag to
+# NO turns the diagrams off. Note that this option also works with HAVE_DOT
+# disabled, but it is recommended to install and use dot, since it yields more
+# powerful graphs.
+# The default value is: YES.
+
+CLASS_DIAGRAMS         = YES
+
+# You can define message sequence charts within doxygen comments using the \msc
+# command. Doxygen will then run the mscgen tool (see:
+# http://www.mcternan.me.uk/mscgen/)) to produce the chart and insert it in the
+# documentation. The MSCGEN_PATH tag allows you to specify the directory where
+# the mscgen tool resides. If left empty the tool is assumed to be found in the
+# default search path.
+
+MSCGEN_PATH            =
+
+# You can include diagrams made with dia in doxygen documentation. Doxygen will
+# then run dia to produce the diagram and insert it in the documentation. The
+# DIA_PATH tag allows you to specify the directory where the dia binary resides.
+# If left empty dia is assumed to be found in the default search path.
+
+DIA_PATH               =
+
+# If set to YES the inheritance and collaboration graphs will hide inheritance
+# and usage relations if the target is undocumented or is not a class.
+# The default value is: YES.
+
+HIDE_UNDOC_RELATIONS   = YES
+
+# If you set the HAVE_DOT tag to YES then doxygen will assume the dot tool is
+# available from the path. This tool is part of Graphviz (see:
+# http://www.graphviz.org/), a graph visualization toolkit from AT&T and Lucent
+# Bell Labs. The other options in this section have no effect if this option is
+# set to NO
+# The default value is: NO.
+
+HAVE_DOT               = NO
+
+# The DOT_NUM_THREADS specifies the number of dot invocations doxygen is allowed
+# to run in parallel. When set to 0 doxygen will base this on the number of
+# processors available in the system. You can set it explicitly to a value
+# larger than 0 to get control over the balance between CPU load and processing
+# speed.
+# Minimum value: 0, maximum value: 32, default value: 0.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_NUM_THREADS        = 0
+
+# When you want a differently looking font in the dot files that doxygen
+# generates you can specify the font name using DOT_FONTNAME. You need to make
+# sure dot is able to find the font, which can be done by putting it in a
+# standard location or by setting the DOTFONTPATH environment variable or by
+# setting DOT_FONTPATH to the directory containing the font.
+# The default value is: Helvetica.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_FONTNAME           = Helvetica
+
+# The DOT_FONTSIZE tag can be used to set the size (in points) of the font of
+# dot graphs.
+# Minimum value: 4, maximum value: 24, default value: 10.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_FONTSIZE           = 10
+
+# By default doxygen will tell dot to use the default font as specified with
+# DOT_FONTNAME. If you specify a different font using DOT_FONTNAME you can set
+# the path where dot can find it using this tag.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_FONTPATH           =
+
+# If the CLASS_GRAPH tag is set to YES then doxygen will generate a graph for
+# each documented class showing the direct and indirect inheritance relations.
+# Setting this tag to YES will force the CLASS_DIAGRAMS tag to NO.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+CLASS_GRAPH            = YES
+
+# If the COLLABORATION_GRAPH tag is set to YES then doxygen will generate a
+# graph for each documented class showing the direct and indirect implementation
+# dependencies (inheritance, containment, and class references variables) of the
+# class with other documented classes.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+COLLABORATION_GRAPH    = YES
+
+# If the GROUP_GRAPHS tag is set to YES then doxygen will generate a graph for
+# groups, showing the direct groups dependencies.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+GROUP_GRAPHS           = YES
+
+# If the UML_LOOK tag is set to YES, doxygen will generate inheritance and
+# collaboration diagrams in a style similar to the OMG's Unified Modeling
+# Language.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+UML_LOOK               = NO
+
+# If the UML_LOOK tag is enabled, the fields and methods are shown inside the
+# class node. If there are many fields or methods and many nodes the graph may
+# become too big to be useful. The UML_LIMIT_NUM_FIELDS threshold limits the
+# number of items for each type to make the size more manageable. Set this to 0
+# for no limit. Note that the threshold may be exceeded by 50% before the limit
+# is enforced. So when you set the threshold to 10, up to 15 fields may appear,
+# but if the number exceeds 15, the total amount of fields shown is limited to
+# 10.
+# Minimum value: 0, maximum value: 100, default value: 10.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+UML_LIMIT_NUM_FIELDS   = 10
+
+# If the TEMPLATE_RELATIONS tag is set to YES then the inheritance and
+# collaboration graphs will show the relations between templates and their
+# instances.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+TEMPLATE_RELATIONS     = NO
+
+# If the INCLUDE_GRAPH, ENABLE_PREPROCESSING and SEARCH_INCLUDES tags are set to
+# YES then doxygen will generate a graph for each documented file showing the
+# direct and indirect include dependencies of the file with other documented
+# files.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+INCLUDE_GRAPH          = YES
+
+# If the INCLUDED_BY_GRAPH, ENABLE_PREPROCESSING and SEARCH_INCLUDES tags are
+# set to YES then doxygen will generate a graph for each documented file showing
+# the direct and indirect include dependencies of the file with other documented
+# files.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+INCLUDED_BY_GRAPH      = YES
+
+# If the CALL_GRAPH tag is set to YES then doxygen will generate a call
+# dependency graph for every global function or class method.
+#
+# Note that enabling this option will significantly increase the time of a run.
+# So in most cases it will be better to enable call graphs for selected
+# functions only using the \callgraph command. Disabling a call graph can be
+# accomplished by means of the command \hidecallgraph.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+CALL_GRAPH             = NO
+
+# If the CALLER_GRAPH tag is set to YES then doxygen will generate a caller
+# dependency graph for every global function or class method.
+#
+# Note that enabling this option will significantly increase the time of a run.
+# So in most cases it will be better to enable caller graphs for selected
+# functions only using the \callergraph command. Disabling a caller graph can be
+# accomplished by means of the command \hidecallergraph.
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+CALLER_GRAPH           = NO
+
+# If the GRAPHICAL_HIERARCHY tag is set to YES then doxygen will graphical
+# hierarchy of all classes instead of a textual one.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+GRAPHICAL_HIERARCHY    = YES
+
+# If the DIRECTORY_GRAPH tag is set to YES then doxygen will show the
+# dependencies a directory has on other directories in a graphical way. The
+# dependency relations are determined by the #include relations between the
+# files in the directories.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DIRECTORY_GRAPH        = YES
+
+# The DOT_IMAGE_FORMAT tag can be used to set the image format of the images
+# generated by dot. For an explanation of the image formats see the section
+# output formats in the documentation of the dot tool (Graphviz (see:
+# http://www.graphviz.org/)).
+# Note: If you choose svg you need to set HTML_FILE_EXTENSION to xhtml in order
+# to make the SVG files visible in IE 9+ (other browsers do not have this
+# requirement).
+# Possible values are: png, jpg, gif, svg, png:gd, png:gd:gd, png:cairo,
+# png:cairo:gd, png:cairo:cairo, png:cairo:gdiplus, png:gdiplus and
+# png:gdiplus:gdiplus.
+# The default value is: png.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_IMAGE_FORMAT       = png
+
+# If DOT_IMAGE_FORMAT is set to svg, then this option can be set to YES to
+# enable generation of interactive SVG images that allow zooming and panning.
+#
+# Note that this requires a modern browser other than Internet Explorer. Tested
+# and working are Firefox, Chrome, Safari, and Opera.
+# Note: For IE 9+ you need to set HTML_FILE_EXTENSION to xhtml in order to make
+# the SVG files visible. Older versions of IE do not have SVG support.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+INTERACTIVE_SVG        = NO
+
+# The DOT_PATH tag can be used to specify the path where the dot tool can be
+# found. If left blank, it is assumed the dot tool can be found in the path.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_PATH               =
+
+# The DOTFILE_DIRS tag can be used to specify one or more directories that
+# contain dot files that are included in the documentation (see the \dotfile
+# command).
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOTFILE_DIRS           =
+
+# The MSCFILE_DIRS tag can be used to specify one or more directories that
+# contain msc files that are included in the documentation (see the \mscfile
+# command).
+
+MSCFILE_DIRS           =
+
+# The DIAFILE_DIRS tag can be used to specify one or more directories that
+# contain dia files that are included in the documentation (see the \diafile
+# command).
+
+DIAFILE_DIRS           =
+
+# When using plantuml, the PLANTUML_JAR_PATH tag should be used to specify the
+# path where java can find the plantuml.jar file. If left blank, it is assumed
+# PlantUML is not used or called during a preprocessing step. Doxygen will
+# generate a warning when it encounters a \startuml command in this case and
+# will not generate output for the diagram.
+
+PLANTUML_JAR_PATH      =
+
+# When using plantuml, the PLANTUML_CFG_FILE tag can be used to specify a
+# configuration file for plantuml.
+
+PLANTUML_CFG_FILE      =
+
+# When using plantuml, the specified paths are searched for files specified by
+# the !include statement in a plantuml block.
+
+PLANTUML_INCLUDE_PATH  =
+
+# The DOT_GRAPH_MAX_NODES tag can be used to set the maximum number of nodes
+# that will be shown in the graph. If the number of nodes in a graph becomes
+# larger than this value, doxygen will truncate the graph, which is visualized
+# by representing a node as a red box. Note that doxygen if the number of direct
+# children of the root node in a graph is already larger than
+# DOT_GRAPH_MAX_NODES then the graph will not be shown at all. Also note that
+# the size of a graph can be further restricted by MAX_DOT_GRAPH_DEPTH.
+# Minimum value: 0, maximum value: 10000, default value: 50.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_GRAPH_MAX_NODES    = 50
+
+# The MAX_DOT_GRAPH_DEPTH tag can be used to set the maximum depth of the graphs
+# generated by dot. A depth value of 3 means that only nodes reachable from the
+# root by following a path via at most 3 edges will be shown. Nodes that lay
+# further from the root node will be omitted. Note that setting this option to 1
+# or 2 may greatly reduce the computation time needed for large code bases. Also
+# note that the size of a graph can be further restricted by
+# DOT_GRAPH_MAX_NODES. Using a depth of 0 means no depth restriction.
+# Minimum value: 0, maximum value: 1000, default value: 0.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+MAX_DOT_GRAPH_DEPTH    = 0
+
+# Set the DOT_TRANSPARENT tag to YES to generate images with a transparent
+# background. This is disabled by default, because dot on Windows does not seem
+# to support this out of the box.
+#
+# Warning: Depending on the platform used, enabling this option may lead to
+# badly anti-aliased labels on the edges of a graph (i.e. they become hard to
+# read).
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_TRANSPARENT        = NO
+
+# Set the DOT_MULTI_TARGETS tag to YES to allow dot to generate multiple output
+# files in one run (i.e. multiple -o and -T options on the command line). This
+# makes dot run faster, but since only newer versions of dot (>1.8.10) support
+# this, this feature is disabled by default.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_MULTI_TARGETS      = NO
+
+# If the GENERATE_LEGEND tag is set to YES doxygen will generate a legend page
+# explaining the meaning of the various boxes and arrows in the dot generated
+# graphs.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+GENERATE_LEGEND        = YES
+
+# If the DOT_CLEANUP tag is set to YES, doxygen will remove the intermediate dot
+# files that are used to generate the various graphs.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_CLEANUP            = YES
diff --git a/libs/tdlib/td/LICENSE_1_0.txt b/libs/tdlib/td/LICENSE_1_0.txt
new file mode 100644
index 0000000000..36b7cd93cd
--- /dev/null
+++ b/libs/tdlib/td/LICENSE_1_0.txt
@@ -0,0 +1,23 @@
+Boost Software License - Version 1.0 - August 17th, 2003
+
+Permission is hereby granted, free of charge, to any person or organization
+obtaining a copy of the software and accompanying documentation covered by
+this license (the "Software") to use, reproduce, display, distribute,
+execute, and transmit the Software, and to prepare derivative works of the
+Software, and to permit third-parties to whom the Software is furnished to
+do so, all subject to the following:
+
+The copyright notices in the Software and this entire statement, including
+the above license grant, this restriction and the following disclaimer,
+must be included in all copies of the Software, in whole or in part, and
+all derivative works of the Software, unless such copies or derivative
+works are solely in the form of machine-executable object code generated by
+a source language processor.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
diff --git a/libs/tdlib/td/README.md b/libs/tdlib/td/README.md
new file mode 100644
index 0000000000..00e94cabff
--- /dev/null
+++ b/libs/tdlib/td/README.md
@@ -0,0 +1,152 @@
+# TDLib
+
+TDLib (Telegram Database library) is a cross-platform library for building [Telegram](https://telegram.org) clients. It can be easily used from almost any programming language.
+
+## Table of Contents
+- [Features](#features)
+- [Examples and documentation](#usage)
+- [Dependencies](#dependencies)
+- [Building](#building)
+- [Installing dependencies](#installing-dependencies)
+- [Using in CMake C++ projects](#using-cxx)
+- [Using in Java projects](#using-java)
+- [Using in .NET projects](#using-dotnet)
+- [Using with other programming languages](#using-json)
+- [License](#license)
+
+<a name="features"></a>
+## Features
+
+`TDLib` has many advantages. Notably `TDLib` is:
+
+* **Cross-platform**: `TDLib` can be used on Android, iOS, Windows, macOS, Linux, Windows Phone, WebAssembly, watchOS, tvOS, Tizen, Cygwin. It should also work on other *nix systems with or without minimal effort.
+* **Multilanguage**: `TDLib` can be easily used with any programming language that is able to execute C functions. Additionally it already has native Java (using `JNI`) bindings and .NET (using `C++/CLI` and `C++/CX`) bindings.
+* **Easy to use**: `TDLib` takes care of all network implementation details, encryption and local data storage.
+* **High-performance**: in the [Telegram Bot API](https://core.telegram.org/bots/api), each `TDLib` instance handles more than 19000 active bots simultaneously.
+* **Well-documented**: all `TDLib` API methods and public interfaces are fully documented.
+* **Consistent**: `TDLib` guarantees that all updates are delivered in the right order.
+* **Reliable**: `TDLib` remains stable on slow and unreliable Internet connections.
+* **Secure**: all local data is encrypted using a user-provided encryption key.
+* **Fully-asynchronous**: requests to `TDLib` don't block each other or anything else, responses are sent when they are available.
+
+<a name="usage"></a>
+## Examples and documentation
+Take a look at our [examples](https://github.com/tdlib/td/tree/master/example) and [documentation](https://core.telegram.org/tdlib/docs/).
+
+<a name="dependencies"></a>
+## Dependencies
+`TDLib` depends on:
+
+* C++14 compatible compiler (Clang 3.4+, GCC 4.9+, MSVC 19.0+ (Visual Studio 2015+), Intel C++ Compiler 17+)
+* OpenSSL
+* zlib
+* gperf (build only)
+* CMake (3.0.2+, build only)
+* PHP (optional, for documentation generation)
+* Doxygen (optional, for documentation generation)
+
+<a name="building"></a>
+## Building
+
+Install all `TDLib` dependencies as described in [Installing dependencies](#installing-dependencies).
+Then enter directory containing `TDLib` sources and compile them using CMake:
+
+```
+mkdir build
+cd build
+cmake -DCMAKE_BUILD_TYPE=Release ..
+cmake --build .
+```
+
+<a name="installing-dependencies"></a>
+### Installing dependencies
+
+<a name="macos"></a>
+#### macOS
+* Install the latest Xcode command line tools.
+* Install other dependencies, for example, using [Homebrew](https://brew.sh):
+```
+brew install gperf cmake openssl
+```
+* Build `TDLib` with CMake as explained in [building](#building). You may need to manually specify path to the installed OpenSSL to CMake, e.g.,
+```
+cmake -DCMAKE_BUILD_TYPE=Release -DOPENSSL_ROOT_DIR=/usr/local/opt/openssl/ ..
+```
+
+<a name="windows"></a>
+#### Windows
+* Download and install [gperf](https://sourceforge.net/projects/gnuwin32/files/gperf/3.0.1/). Add the path to gperf.exe to the PATH environment variable.
+* Install [vcpkg](https://github.com/Microsoft/vcpkg#quick-start).
+* Run the following commands to install `TDLib` dependencies using vcpkg:
+```
+C:\src\vcpkg> .\vcpkg.exe install openssl:x64-windows openssl:x86-windows zlib:x64-windows zlib:x86-windows
+```
+* Build `TDLib` with CMake as explained in [building](#building), but instead of `cmake -DCMAKE_BUILD_TYPE=Release ..` use
+```
+cmake -DCMAKE_TOOLCHAIN_FILE=C:\src\vcpkg\scripts\buildsystems\vcpkg.cmake ..
+```
+
+To build 64-bit `TDLib` using MSVC, you will need to additionally specify parameter `-A x64` to CMake.
+To build `TDLib` in Release mode using MSVC, you will need to additionally specify parameter `--config Release` to the `cmake --build .` command.
+
+<a name="linux"></a>
+#### Linux
+* Install all dependencies using your package manager.
+
+<a name="using-cxx"></a>
+## Using in CMake C++ projects
+For C++ projects that use CMake, the best approach is to build `TDLib` as part of your project or to use a prebuilt installation.
+
+There are several libraries that you could use in your CMake project:
+
+* Td::TdJson, Td::TdJsonStatic — dynamic and static version of a JSON interface. This has a simple C interface, so it can be easily used with any programming language that is able to execute C functions.
+  See [td_json_client](https://core.telegram.org/tdlib/docs/td__json__client_8h.html) and [td_log](https://core.telegram.org/tdlib/docs/td__log_8h.html) documentation for more information.
+* Td::TdStatic — static library with C++ interface for general usage.
+  See [Client](https://core.telegram.org/tdlib/docs/classtd_1_1_client.html) and [Log](https://core.telegram.org/tdlib/docs/classtd_1_1_log.html) documentation for more information.
+* Td::TdCoreStatic — static library with low-level C++ interface intended mostly for internal usage.
+  See [ClientActor](https://core.telegram.org/tdlib/docs/classtd_1_1_client_actor.html) and [Log](https://core.telegram.org/tdlib/docs/classtd_1_1_log.html) documentation for more information.
+
+For example, part of your CMakeLists.txt may look like this:
+```
+add_subdirectory(td)
+target_link_libraries(YourTarget PRIVATE Td::TdStatic)
+```
+
+Or you could install `TDLib` and then reference it in your CMakeLists.txt like this:
+```
+find_package(Td 1.2.0 REQUIRED)
+target_link_libraries(YourTarget PRIVATE Td::TdStatic)
+```
+See [example/cpp/CMakeLists.txt](https://github.com/tdlib/td/tree/master/example/cpp/CMakeLists.txt).
+
+<a name="using-java"></a>
+## Using in Java projects
+`TDLib` provides native Java interface through JNI. To enable it, specify option `-DTD_ENABLE_JNI=ON` to CMake.
+
+See [example/java](https://github.com/tdlib/td/tree/master/example/java) for example of using `TDLib` from Java and detailed build and usage instructions.
+
+<a name="using-dotnet"></a>
+## Using in .NET projects
+`TDLib` provides native .NET interface through `C++/CLI` and `C++/CX`. To enable it, specify option `-DTD_ENABLE_DOTNET=ON` to CMake.
+.NET Core doesn't support `C++/CLI`, so if .NET Core is used, then `TDLib` JSON interface should be used through P/Invoke instead.
+
+See [example/csharp](https://github.com/tdlib/td/tree/master/example/csharp) for example of using `TDLib` from C# and detailed build and usage instructions.
+See [example/uwp](https://github.com/tdlib/td/tree/master/example/uwp) for example of using `TDLib` from C# UWP application and detailed build and usage instructions for Visual Studio Extension "TDLib for Universal Windows Platform".
+
+When `TDLib` is built with `TD_ENABLE_DOTNET` option enabled, `C++` documentation is removed from some files. You need to checkout these files to return `C++` documentation back:
+```
+git checkout td/telegram/Client.h td/telegram/Log.h td/tl/TlObject.h
+```
+
+<a name="using-json"></a>
+## Using from other programming languages
+`TDLib` provides efficient native C++, Java, and .NET interfaces.
+But for most use cases we suggest to use the JSON interface, which can be easily used with any programming language that is able to execute C functions.
+See [td_json_client](https://core.telegram.org/tdlib/docs/td__json__client_8h.html) and [td_log](https://core.telegram.org/tdlib/docs/td__log_8h.html) documentation for detailed JSON interface description,
+scheme [td_api.tl](https://github.com/tdlib/td/blob/master/td/generate/scheme/td_api.tl) or autogenerated [HTML documentation](https://core.telegram.org/tdlib/docs/td__api_8h.html) for the list of all available `TDLib` methods and classes.
+
+See [example/python/tdjson_example.py](https://github.com/tdlib/td/tree/master/example/python/tdjson_example.py) and [example/ruby/example.rb](https://github.com/tdlib/td/tree/master/example/ruby/example.rb) for an example of such usage.
+
+<a name="license"></a>
+## License
+`TDLib` is licensed under the terms of the Boost Software License. See [LICENSE_1_0.txt](http://www.boost.org/LICENSE_1_0.txt) for more information.
diff --git a/libs/tdlib/td/TdConfig.cmake b/libs/tdlib/td/TdConfig.cmake
new file mode 100644
index 0000000000..3cdff38c2a
--- /dev/null
+++ b/libs/tdlib/td/TdConfig.cmake
@@ -0,0 +1,3 @@
+include(CMakeFindDependencyMacro)
+#TODO: write all external dependencies
+include("${CMAKE_CURRENT_LIST_DIR}/TdTargets.cmake")
diff --git a/libs/tdlib/td/benchmark/CMakeLists.txt b/libs/tdlib/td/benchmark/CMakeLists.txt
new file mode 100644
index 0000000000..90f294fbc9
--- /dev/null
+++ b/libs/tdlib/td/benchmark/CMakeLists.txt
@@ -0,0 +1,59 @@
+cmake_minimum_required(VERSION 3.0.2 FATAL_ERROR)
+
+if (NOT OPENSSL_FOUND)
+  find_package(OpenSSL REQUIRED)
+  find_package(ZLIB REQUIRED)
+endif()
+
+#TODO: all benchmarks in one file
+add_executable(bench_crypto bench_crypto.cpp)
+target_link_libraries(bench_crypto PRIVATE tdcore tdutils ${OPENSSL_CRYPTO_LIBRARY} ${CMAKE_DL_LIBS} ${ZLIB_LIBRARIES})
+target_include_directories(bench_crypto SYSTEM PRIVATE ${OPENSSL_INCLUDE_DIR})
+
+add_executable(bench_actor bench_actor.cpp)
+target_link_libraries(bench_actor PRIVATE tdactor tdutils)
+
+add_executable(bench_http bench_http.cpp)
+target_link_libraries(bench_http PRIVATE tdnet tdutils)
+
+add_executable(bench_http_server bench_http_server.cpp)
+target_link_libraries(bench_http_server PRIVATE tdnet tdutils)
+
+add_executable(bench_http_server_cheat bench_http_server_cheat.cpp)
+target_link_libraries(bench_http_server_cheat PRIVATE tdnet tdutils)
+
+add_executable(bench_http_server_fast bench_http_server_fast.cpp)
+target_link_libraries(bench_http_server_fast PRIVATE tdnet tdutils)
+
+add_executable(bench_http_reader bench_http_reader.cpp)
+target_link_libraries(bench_http_reader PRIVATE tdnet tdutils)
+
+add_executable(bench_handshake bench_handshake.cpp)
+target_link_libraries(bench_handshake PRIVATE tdcore tdutils)
+
+add_executable(bench_db bench_db.cpp)
+target_link_libraries(bench_db PRIVATE tdactor tddb tdutils)
+
+add_executable(bench_tddb bench_tddb.cpp)
+target_link_libraries(bench_tddb PRIVATE tdcore tddb tdutils)
+
+add_executable(bench_misc bench_misc.cpp)
+target_link_libraries(bench_misc PRIVATE tdcore tdutils)
+
+add_executable(rmdir rmdir.cpp)
+target_link_libraries(rmdir PRIVATE tdutils)
+
+add_executable(wget wget.cpp)
+target_link_libraries(wget PRIVATE tdnet tdutils)
+
+add_executable(bench_empty bench_empty.cpp)
+target_link_libraries(bench_empty PRIVATE tdutils)
+
+if (NOT WIN32 AND NOT CYGWIN)
+  add_executable(bench_log bench_log.cpp)
+  target_link_libraries(bench_log PRIVATE tdutils)
+
+  set_source_files_properties(bench_queue.cpp PROPERTIES COMPILE_FLAGS -Wno-deprecated-declarations)
+  add_executable(bench_queue bench_queue.cpp)
+  target_link_libraries(bench_queue PRIVATE tdutils)
+endif()
diff --git a/libs/tdlib/td/benchmark/bench_actor.cpp b/libs/tdlib/td/benchmark/bench_actor.cpp
new file mode 100644
index 0000000000..a966d601cf
--- /dev/null
+++ b/libs/tdlib/td/benchmark/bench_actor.cpp
@@ -0,0 +1,290 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/benchmark.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/utils/logging.h"
+
+#include <algorithm>
+
+#if TD_MSVC
+#pragma comment(linker, "/STACK:16777216")
+#endif
+
+template <int type>
+class RingBench : public td::Benchmark {
+ public:
+  struct PassActor;
+
+ private:
+  int actor_n_;
+  int thread_n_;
+  std::vector<td::ActorId<PassActor>> actor_array_;
+  td::ConcurrentScheduler *scheduler_;
+
+ public:
+  std::string get_description() const override {
+    static const char *types[] = {"later", "immediate", "raw", "tail", "lambda"};
+    static_assert(0 <= type && type < 5, "");
+    return PSTRING() << "Ring (send_" << types[type] << ") (threads_n = " << thread_n_ << ")";
+  }
+
+  struct PassActor : public td::Actor {
+    int id;
+    td::ActorId<PassActor> next_actor;
+    int start_n = 0;
+
+    void pass(int n) {
+      // LOG(INFO) << "pass: " << n;
+      if (n == 0) {
+        td::Scheduler::instance()->finish();
+      } else {
+        if (type == 0) {
+          send_closure_later(next_actor, &PassActor::pass, n - 1);
+        } else if (type == 1) {
+          send_closure(next_actor, &PassActor::pass, n - 1);
+        } else if (type == 2) {
+          send_event(next_actor, td::Event::raw(static_cast<td::uint32>(n - 1)));
+        } else if (type == 3) {
+          if (n % 5000 == 0) {
+            send_closure_later(next_actor, &PassActor::pass, n - 1);
+          } else {
+            // TODO: it is three times faster than send_event
+            // may be send event could be further optimized?
+            ::td::Scheduler::instance()->hack(static_cast<td::ActorId<Actor>>(next_actor),
+                                              td::Event::raw(static_cast<td::uint32>(n - 1)));
+          }
+        } else if (type == 4) {
+          send_lambda(next_actor, [=, ptr = next_actor.get_actor_unsafe()] { ptr->pass(n - 1); });
+        }
+      }
+    }
+
+    void raw_event(const td::Event::Raw &raw) override {
+      pass(static_cast<int>(raw.u32));
+    }
+
+    void start_up() override {
+      yield();
+    }
+    void wakeup() override {
+      if (start_n != 0) {
+        int n = start_n;
+        start_n = 0;
+        pass(n);
+      }
+    }
+  };
+
+  RingBench(int actor_n, int thread_n) : actor_n_(actor_n), thread_n_(thread_n) {
+  }
+
+  void start_up() override {
+    scheduler_ = new td::ConcurrentScheduler();
+    scheduler_->init(thread_n_);
+
+    actor_array_ = std::vector<td::ActorId<PassActor>>(actor_n_);
+    for (int i = 0; i < actor_n_; i++) {
+      actor_array_[i] =
+          scheduler_->create_actor_unsafe<PassActor>(thread_n_ ? i % thread_n_ : 0, "PassActor").release();
+      actor_array_[i].get_actor_unsafe()->id = i;
+    }
+    for (int i = 0; i < actor_n_; i++) {
+      actor_array_[i].get_actor_unsafe()->next_actor = actor_array_[(i + 1) % actor_n_];
+    }
+    scheduler_->start();
+  }
+
+  void run(int n) override {
+    // first actor is on main_thread
+    actor_array_[0].get_actor_unsafe()->start_n = std::max(n, 100);
+    while (scheduler_->run_main(10)) {
+      // empty
+    }
+  }
+
+  void tear_down() override {
+    scheduler_->finish();
+    delete scheduler_;
+  }
+};
+
+template <int type>
+class QueryBench : public td::Benchmark {
+ public:
+  std::string get_description() const override {
+    static const char *types[] = {"callback", "immediate future", "delayed future", "dummy", "lambda", "lambda_future"};
+    static_assert(0 <= type && type < 6, "");
+    return PSTRING() << "QueryBench: " << types[type];
+  }
+
+  class ClientActor : public td::Actor {
+   public:
+    class Callback {
+     public:
+      Callback() = default;
+      Callback(const Callback &) = delete;
+      Callback &operator=(const Callback &) = delete;
+      Callback(Callback &&) = delete;
+      Callback &operator=(Callback &&) = delete;
+      virtual ~Callback() = default;
+      virtual void on_result(int x) = 0;
+    };
+    explicit ClientActor(std::unique_ptr<Callback> callback) : callback_(std::move(callback)) {
+    }
+    void f(int x) {
+      callback_->on_result(x * x);
+    }
+    void dummy(int x, int *y) {
+      *y = x * x;
+    }
+    void f_immediate_promise(int x, td::PromiseActor<int> &&promise) {
+      promise.set_value(x * x);
+    }
+    void f_promise(td::Promise<> promise) {
+      promise.set_value(td::Unit());
+    }
+
+   private:
+    std::unique_ptr<Callback> callback_;
+  };
+
+  class ServerActor : public td::Actor {
+   public:
+    class ClientCallback : public ClientActor::Callback {
+     public:
+      explicit ClientCallback(td::ActorId<ServerActor> server) : server_(server) {
+      }
+      void on_result(int x) override {
+        send_closure(server_, &ServerActor::on_result, x);
+      }
+
+     private:
+      td::ActorId<ServerActor> server_;
+    };
+    void start_up() override {
+      client_ = td::create_actor<ClientActor>("Client", td::make_unique<ClientCallback>(actor_id(this))).release();
+    }
+
+    void on_result(int x) {
+      CHECK(x == n_ * n_);
+      wakeup();
+    }
+
+    void wakeup() override {
+      while (true) {
+        if (n_ < 0) {
+          td::Scheduler::instance()->finish();
+          return;
+        }
+        n_--;
+        if (type == 0) {
+          send_closure(client_, &ClientActor::f, n_);
+          return;
+        } else if (type == 1) {
+          td::PromiseActor<int> promise;
+          td::FutureActor<int> future;
+          init_promise_future(&promise, &future);
+          send_closure(client_, &ClientActor::f_immediate_promise, n_, std::move(promise));
+          int val = future.move_as_ok();
+          CHECK(val == n_ * n_);
+        } else if (type == 2) {
+          td::PromiseActor<int> promise;
+          init_promise_future(&promise, &future_);
+          future_.set_event(td::EventCreator::raw(actor_id(), static_cast<td::uint64>(1)));
+          send_closure(client_, &ClientActor::f_immediate_promise, n_, std::move(promise));
+          return;
+        } else if (type == 3) {
+          int res;
+          send_closure(client_, &ClientActor::dummy, n_, &res);
+        } else if (type == 4) {
+          int val = 0;
+          send_lambda(client_, [&] { val = n_ * n_; });
+        } else if (type == 5) {
+          send_closure(client_, &ClientActor::f_promise,
+                       td::PromiseCreator::lambda(
+                           [id = actor_id(this), n = n_](td::Unit) { send_closure(id, &ServerActor::result, n * n); }));
+          return;
+        }
+      }
+    }
+
+    void run(int n) {
+      n_ = n;
+      wakeup();
+    }
+
+    void raw_event(const td::Event::Raw &event) override {
+      int val = future_.move_as_ok();
+      CHECK(val == n_ * n_);
+      wakeup();
+    }
+    void result(int val) {
+      CHECK(val == n_ * n_);
+      wakeup();
+    }
+
+   private:
+    td::ActorId<ClientActor> client_;
+    int n_;
+    td::FutureActor<int> future_;
+  };
+
+  void start_up() override {
+    scheduler_ = new td::ConcurrentScheduler();
+    scheduler_->init(0);
+
+    server_ = scheduler_->create_actor_unsafe<ServerActor>(0, "Server");
+    scheduler_->start();
+  }
+
+  void run(int n) override {
+    // first actor is on main_thread
+    {
+      auto guard = scheduler_->get_current_guard();
+      send_closure(server_, &ServerActor::run, n);
+    }
+    while (scheduler_->run_main(10)) {
+      // empty
+    }
+  }
+
+  void tear_down() override {
+    server_.release();
+    scheduler_->finish();
+    delete scheduler_;
+  }
+
+ private:
+  td::ConcurrentScheduler *scheduler_;
+  td::ActorOwn<ServerActor> server_;
+};
+
+int main() {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(DEBUG));
+  bench(RingBench<4>(504, 0));
+  bench(RingBench<3>(504, 0));
+  bench(RingBench<0>(504, 0));
+  bench(RingBench<1>(504, 0));
+  bench(RingBench<2>(504, 0));
+  bench(QueryBench<5>());
+  bench(QueryBench<4>());
+  bench(QueryBench<2>());
+  bench(QueryBench<3>());
+  bench(QueryBench<1>());
+  bench(QueryBench<0>());
+  bench(RingBench<3>(504, 0));
+  bench(RingBench<0>(504, 10));
+  bench(RingBench<1>(504, 10));
+  bench(RingBench<2>(504, 10));
+  bench(RingBench<0>(504, 2));
+  bench(RingBench<1>(504, 2));
+  bench(RingBench<2>(504, 2));
+  return 0;
+}
diff --git a/libs/tdlib/td/benchmark/bench_crypto.cpp b/libs/tdlib/td/benchmark/bench_crypto.cpp
new file mode 100644
index 0000000000..44d309ef11
--- /dev/null
+++ b/libs/tdlib/td/benchmark/bench_crypto.cpp
@@ -0,0 +1,213 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/benchmark.h"
+
+#include "td/utils/crypto.h"
+#include "td/utils/int_types.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/thread.h"
+#include "td/utils/Random.h"
+#include "td/utils/Slice.h"
+
+#include <openssl/sha.h>
+
+#include <array>
+#include <atomic>
+#include <cstdint>
+#include <cstdlib>
+#include <random>
+#include <string>
+#include <vector>
+
+static constexpr int DATA_SIZE = 8 << 10;
+
+class SHA1Bench : public td::Benchmark {
+ public:
+  alignas(64) unsigned char data[DATA_SIZE];
+
+  std::string get_description() const override {
+    return PSTRING() << "SHA1 OpenSSL [" << (DATA_SIZE >> 10) << "KB]";
+  }
+
+  void start_up() override {
+    for (int i = 0; i < DATA_SIZE; i++) {
+      data[i] = 123;
+      data[i] = 0;
+    }
+  }
+
+  void run(int n) override {
+    for (int i = 0; i < n; i++) {
+      unsigned char md[20];
+      SHA1(data, DATA_SIZE, md);
+    }
+  }
+};
+
+class AESBench : public td::Benchmark {
+ public:
+  alignas(64) unsigned char data[DATA_SIZE];
+  td::UInt256 key;
+  td::UInt256 iv;
+
+  std::string get_description() const override {
+    return PSTRING() << "AES OpenSSL [" << (DATA_SIZE >> 10) << "KB]";
+  }
+
+  void start_up() override {
+    for (int i = 0; i < DATA_SIZE; i++) {
+      data[i] = 123;
+    }
+    td::Random::secure_bytes(key.raw, sizeof(key));
+    td::Random::secure_bytes(iv.raw, sizeof(iv));
+  }
+
+  void run(int n) override {
+    td::MutableSlice data_slice(data, DATA_SIZE);
+    for (int i = 0; i < n; i++) {
+      td::aes_ige_encrypt(key, &iv, data_slice, data_slice);
+    }
+  }
+};
+
+BENCH(Rand, "std_rand") {
+  int res = 0;
+  for (int i = 0; i < n; i++) {
+    res ^= std::rand();
+  }
+  td::do_not_optimize_away(res);
+}
+
+BENCH(CppRand, "mt19937_rand") {
+  std::uint_fast32_t res = 0;
+  std::mt19937 g(123);
+  for (int i = 0; i < n; i++) {
+    res ^= g();
+  }
+  td::do_not_optimize_away(res);
+}
+
+BENCH(TdRand32, "td_rand_fast32") {
+  td::uint32 res = 0;
+  for (int i = 0; i < n; i++) {
+    res ^= td::Random::fast_uint32();
+  }
+  td::do_not_optimize_away(res);
+}
+
+BENCH(TdRandFast, "td_rand_fast") {
+  int res = 0;
+  for (int i = 0; i < n; i++) {
+    res ^= td::Random::fast(0, RAND_MAX);
+  }
+  td::do_not_optimize_away(res);
+}
+
+#if !TD_THREAD_UNSUPPORTED
+BENCH(SslRand, "ssl_rand_int32") {
+  std::vector<td::thread> v;
+  std::atomic<td::uint32> sum;
+  for (int i = 0; i < 3; i++) {
+    v.push_back(td::thread([&] {
+      td::int32 res = 0;
+      for (int j = 0; j < n; j++) {
+        res ^= td::Random::secure_int32();
+      }
+      sum += res;
+    }));
+  }
+  for (auto &x : v) {
+    x.join();
+  }
+  v.clear();
+  td::do_not_optimize_away(sum.load());
+}
+#endif
+
+BENCH(SslRandBuf, "ssl_rand_bytes") {
+  td::int32 res = 0;
+  std::array<td::int32, 1000> buf;
+  for (int i = 0; i < n; i += static_cast<int>(buf.size())) {
+    td::Random::secure_bytes(reinterpret_cast<td::uint8 *>(buf.data()), sizeof(buf[0]) * buf.size());
+    for (auto x : buf) {
+      res ^= x;
+    }
+  }
+  td::do_not_optimize_away(res);
+}
+
+BENCH(Pbkdf2, "pbkdf2") {
+  std::string password = "cucumber";
+  std::string salt = "abcdefghijklmnopqrstuvw";
+  std::string key(32, ' ');
+  td::pbkdf2_sha256(password, salt, n, key);
+}
+
+class Crc32Bench : public td::Benchmark {
+ public:
+  alignas(64) unsigned char data[DATA_SIZE];
+
+  std::string get_description() const override {
+    return PSTRING() << "Crc32 zlib [" << (DATA_SIZE >> 10) << "KB]";
+  }
+
+  void start_up() override {
+    for (int i = 0; i < DATA_SIZE; i++) {
+      data[i] = 123;
+      data[i] = 0;
+    }
+  }
+
+  void run(int n) override {
+    td::uint64 res = 0;
+    for (int i = 0; i < n; i++) {
+      res += td::crc32(td::Slice(data, DATA_SIZE));
+    }
+    td::do_not_optimize_away(res);
+  }
+};
+
+class Crc64Bench : public td::Benchmark {
+ public:
+  alignas(64) unsigned char data[DATA_SIZE];
+
+  std::string get_description() const override {
+    return PSTRING() << "Crc64 Anton [" << (DATA_SIZE >> 10) << "KB]";
+  }
+
+  void start_up() override {
+    for (int i = 0; i < DATA_SIZE; i++) {
+      data[i] = 123;
+      data[i] = 0;
+    }
+  }
+
+  void run(int n) override {
+    td::uint64 res = 0;
+    for (int i = 0; i < n; i++) {
+      res += td::crc64(td::Slice(data, DATA_SIZE));
+    }
+    td::do_not_optimize_away(res);
+  }
+};
+
+int main() {
+  td::bench(Pbkdf2Bench());
+  td::bench(RandBench());
+  td::bench(CppRandBench());
+  td::bench(TdRand32Bench());
+  td::bench(TdRandFastBench());
+#if !TD_THREAD_UNSUPPORTED
+  td::bench(SslRandBench());
+#endif
+  td::bench(SslRandBufBench());
+  td::bench(SHA1Bench());
+  td::bench(AESBench());
+  td::bench(Crc32Bench());
+  td::bench(Crc64Bench());
+  return 0;
+}
diff --git a/libs/tdlib/td/benchmark/bench_db.cpp b/libs/tdlib/td/benchmark/bench_db.cpp
new file mode 100644
index 0000000000..dc768e9d9d
--- /dev/null
+++ b/libs/tdlib/td/benchmark/bench_db.cpp
@@ -0,0 +1,237 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/actor/actor.h"
+
+#include "td/db/binlog/Binlog.h"
+#include "td/db/BinlogKeyValue.h"
+#include "td/db/SeqKeyValue.h"
+#include "td/db/SqliteDb.h"
+#include "td/db/SqliteKeyValueAsync.h"
+
+#include "td/utils/benchmark.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+
+#include <memory>
+
+template <class KeyValueT>
+class TdKvBench : public td::Benchmark {
+  td::ConcurrentScheduler sched;
+  td::string name_;
+
+ public:
+  explicit TdKvBench(td::string name) {
+    name_ = std::move(name);
+  }
+
+  td::string get_description() const override {
+    return name_;
+  }
+
+  class Main : public td::Actor {
+   public:
+    explicit Main(int n) : n_(n) {
+    }
+
+   private:
+    void loop() override {
+      KeyValueT::destroy("test_tddb").ignore();
+
+      class Worker : public Actor {
+       public:
+        Worker(int n, td::string db_name) : n_(n) {
+          kv_.init(db_name).ensure();
+        }
+
+       private:
+        void loop() override {
+          for (int i = 0; i < n_; i++) {
+            kv_.set(td::to_string(i % 10), td::to_string(i));
+          }
+          td::Scheduler::instance()->finish();
+        }
+        int n_;
+        KeyValueT kv_;
+      };
+      td::create_actor_on_scheduler<Worker>("Worker", 0, n_, "test_tddb").release();
+    }
+    int n_;
+  };
+
+  void start_up_n(int n) override {
+    sched.init(1);
+    sched.create_actor_unsafe<Main>(1, "Main", n).release();
+  }
+
+  void run(int n) override {
+    sched.start();
+    while (sched.run_main(10)) {
+      // empty
+    }
+    sched.finish();
+  }
+
+  void tear_down() override {
+  }
+};
+
+template <bool is_encrypted = false>
+class SqliteKVBench : public td::Benchmark {
+  td::SqliteDb db;
+  td::string get_description() const override {
+    return PSTRING() << "SqliteKV " << td::tag("is_encrypted", is_encrypted);
+  }
+  void start_up() override {
+    td::string path = "testdb.sqlite";
+    td::SqliteDb::destroy(path).ignore();
+    if (is_encrypted) {
+      td::SqliteDb::change_key(path, td::DbKey::password("cucumber"), td::DbKey::empty());
+      db = td::SqliteDb::open_with_key(path, td::DbKey::password("cucumber")).move_as_ok();
+    } else {
+      db = td::SqliteDb::open_with_key(path, td::DbKey::empty()).move_as_ok();
+    }
+    db.exec("PRAGMA encoding=\"UTF-8\"").ensure();
+    db.exec("PRAGMA synchronous=NORMAL").ensure();
+    db.exec("PRAGMA journal_mode=WAL").ensure();
+    db.exec("PRAGMA temp_store=MEMORY").ensure();
+    db.exec("DROP TABLE IF EXISTS KV").ensure();
+    db.exec("CREATE TABLE IF NOT EXISTS KV (k BLOB PRIMARY KEY, v BLOB)").ensure();
+  }
+  void run(int n) override {
+    auto stmt = db.get_statement("REPLACE INTO KV (k, v) VALUES(?1, ?2)").move_as_ok();
+    db.exec("BEGIN TRANSACTION").ensure();
+    for (int i = 0; i < n; i++) {
+      auto key = td::to_string(i % 10);
+      auto value = td::to_string(i);
+      stmt.bind_blob(1, key).ensure();
+      stmt.bind_blob(2, value).ensure();
+      stmt.step().ensure();
+      CHECK(!stmt.can_step());
+      stmt.reset();
+
+      if (i % 10 == 0) {
+        db.exec("COMMIT TRANSACTION").ensure();
+        db.exec("BEGIN TRANSACTION").ensure();
+      }
+    }
+    db.exec("COMMIT TRANSACTION").ensure();
+  }
+};
+
+static td::Status init_db(td::SqliteDb &db) {
+  TRY_STATUS(db.exec("PRAGMA encoding=\"UTF-8\""));
+  TRY_STATUS(db.exec("PRAGMA journal_mode=WAL"));
+
+  TRY_STATUS(db.exec("PRAGMA synchronous=NORMAL"));
+  TRY_STATUS(db.exec("PRAGMA temp_store=MEMORY"));
+  // TRY_STATUS(db.exec("PRAGMA secure_delete=1"));
+
+  return td::Status::OK();
+}
+
+class SqliteKeyValueAsyncBench : public td::Benchmark {
+ public:
+  td::string get_description() const override {
+    return "SqliteKeyValueAsync";
+  }
+  void start_up() override {
+    do_start_up().ensure();
+    scheduler_->start();
+  }
+  void run(int n) override {
+    auto guard = scheduler_->get_current_guard();
+
+    for (int i = 0; i < n; i++) {
+      auto key = td::to_string(i % 10);
+      auto value = td::to_string(i);
+      sqlite_kv_async_->set(key, value, td::Auto());
+    }
+  }
+  void tear_down() override {
+    scheduler_->run_main(0.1);
+    {
+      auto guard = scheduler_->get_current_guard();
+      sqlite_kv_async_.reset();
+      sqlite_kv_safe_.reset();
+      sql_connection_->close_and_destroy();
+    }
+
+    scheduler_->finish();
+    scheduler_.reset();
+  }
+
+ private:
+  std::unique_ptr<td::ConcurrentScheduler> scheduler_;
+  std::shared_ptr<td::SqliteConnectionSafe> sql_connection_;
+  std::shared_ptr<td::SqliteKeyValueSafe> sqlite_kv_safe_;
+  std::unique_ptr<td::SqliteKeyValueAsyncInterface> sqlite_kv_async_;
+
+  td::Status do_start_up() {
+    scheduler_ = std::make_unique<td::ConcurrentScheduler>();
+    scheduler_->init(1);
+
+    auto guard = scheduler_->get_current_guard();
+
+    td::string sql_db_name = "testdb.sqlite";
+    td::SqliteDb::destroy(sql_db_name).ignore();
+
+    sql_connection_ = std::make_shared<td::SqliteConnectionSafe>(sql_db_name);
+    auto &db = sql_connection_->get();
+    TRY_STATUS(init_db(db));
+
+    sqlite_kv_safe_ = std::make_shared<td::SqliteKeyValueSafe>("common", sql_connection_);
+    sqlite_kv_async_ = create_sqlite_key_value_async(sqlite_kv_safe_, 0);
+
+    return td::Status::OK();
+  }
+};
+
+class SeqKvBench : public td::Benchmark {
+  td::string get_description() const override {
+    return "SeqKvBench";
+  }
+
+  td::SeqKeyValue kv;
+  void run(int n) override {
+    for (int i = 0; i < n; i++) {
+      kv.set(td::to_string(i % 10), td::to_string(i));
+    }
+  }
+};
+
+template <bool is_encrypted = false>
+class BinlogKeyValueBench : public td::Benchmark {
+  td::string get_description() const override {
+    return PSTRING() << "BinlogKeyValue " << td::tag("is_encrypted", is_encrypted);
+  }
+
+  td::BinlogKeyValue<td::Binlog> kv;
+  void start_up() override {
+    td::SqliteDb::destroy("test_binlog").ignore();
+    kv.init("test_binlog", is_encrypted ? td::DbKey::password("cucumber") : td::DbKey::empty()).ensure();
+  }
+  void run(int n) override {
+    for (int i = 0; i < n; i++) {
+      kv.set(td::to_string(i % 10), td::to_string(i));
+    }
+  }
+};
+
+int main() {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(WARNING));
+  bench(BinlogKeyValueBench<true>());
+  bench(BinlogKeyValueBench<false>());
+  bench(SqliteKVBench<false>());
+  bench(SqliteKVBench<true>());
+  bench(SqliteKeyValueAsyncBench());
+  bench(TdKvBench<td::BinlogKeyValue<td::Binlog>>("BinlogKeyValue<Binlog>"));
+  bench(TdKvBench<td::BinlogKeyValue<td::ConcurrentBinlog>>("BinlogKeyValue<ConcurrentBinlog>"));
+  bench(SeqKvBench());
+  return 0;
+}
diff --git a/libs/tdlib/td/benchmark/bench_empty.cpp b/libs/tdlib/td/benchmark/bench_empty.cpp
new file mode 100644
index 0000000000..f6718152b4
--- /dev/null
+++ b/libs/tdlib/td/benchmark/bench_empty.cpp
@@ -0,0 +1,9 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+int main() {
+  return 0;
+}
diff --git a/libs/tdlib/td/benchmark/bench_handshake.cpp b/libs/tdlib/td/benchmark/bench_handshake.cpp
new file mode 100644
index 0000000000..08d04f009c
--- /dev/null
+++ b/libs/tdlib/td/benchmark/bench_handshake.cpp
@@ -0,0 +1,76 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/benchmark.h"  // for bench, do_not_optimize_away, etc
+
+#include "td/mtproto/crypto.h"
+
+#include "td/utils/base64.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+
+#include <map>
+
+#if TD_LINUX || TD_ANDROID || TD_TIZEN
+#include <semaphore.h>
+#endif
+
+namespace td {
+
+static int32 g = 3;
+static string prime_base64 =
+    "xxyuucaxyQSObFIvcPE_c5gNQCOOPiHBSTTQN1Y9kw9IGYoKp8FAWCKUk9IlMPTb-jNvbgrJJROVQ67UTM58NyD9UfaUWHBaxozU_mtrE6vcl0ZRKW"
+    "kyhFTxj6-MWV9kJHf-lrsqlB1bzR1KyMxJiAcI-ps3jjxPOpBgvuZ8-aSkppWBEFGQfhYnU7VrD2tBDbp02KhLKhSzFE4O8ShHVP0X7ZUNWWW0ud1G"
+    "WC2xF40WnGvEZbDW_5yjko_vW5rk5Bj8Feg-vqD4f6n_Xu1wBQ3tKEn0e_lZ2VaFDOkphR8NgRX2NbEF7i5OFdBLJFS_b0-t8DSxBAMRnNjjuS_MW"
+    "w";
+
+class HandshakeBench : public Benchmark {
+  std::string get_description() const override {
+    return "Handshake";
+  }
+
+  class FakeDhCallback : public DhCallback {
+   public:
+    int is_good_prime(Slice prime_str) const override {
+      auto it = cache.find(prime_str.str());
+      if (it == cache.end()) {
+        return -1;
+      }
+      return it->second;
+    }
+    void add_good_prime(Slice prime_str) const override {
+      cache[prime_str.str()] = 1;
+    }
+    void add_bad_prime(Slice prime_str) const override {
+      cache[prime_str.str()] = 0;
+    }
+    mutable std::map<string, int> cache;
+  } dh_callback;
+
+  void run(int n) override {
+    DhHandshake a;
+    DhHandshake b;
+    auto prime = base64url_decode(prime_base64).move_as_ok();
+    for (int i = 0; i < n; i += 2) {
+      a.set_config(g, prime);
+      b.set_config(g, prime);
+      b.set_g_a(a.get_g_b());
+      a.set_g_a(b.get_g_b());
+      a.run_checks(&dh_callback).ensure();
+      b.run_checks(&dh_callback).ensure();
+      auto a_key = a.gen_key();
+      auto b_key = b.gen_key();
+      CHECK(a_key.first == b_key.first);
+    }
+  }
+};
+}  // namespace td
+
+int main() {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(DEBUG));
+  td::bench(td::HandshakeBench());
+  return 0;
+}
diff --git a/libs/tdlib/td/benchmark/bench_http.cpp b/libs/tdlib/td/benchmark/bench_http.cpp
new file mode 100644
index 0000000000..6958a5b313
--- /dev/null
+++ b/libs/tdlib/td/benchmark/bench_http.cpp
@@ -0,0 +1,78 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/actor/actor.h"
+
+#include "td/net/HttpOutboundConnection.h"
+#include "td/net/HttpQuery.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/IPAddress.h"
+#include "td/utils/port/SocketFd.h"
+#include "td/utils/Status.h"
+
+#include <atomic>
+#include <limits>
+
+namespace td {
+
+std::atomic<int> counter;
+class HttpClient : public HttpOutboundConnection::Callback {
+  void start_up() override {
+    IPAddress addr;
+    addr.init_ipv4_port("127.0.0.1", 8082).ensure();
+    auto fd = SocketFd::open(addr);
+    CHECK(fd.is_ok()) << fd.error();
+    connection_ =
+        create_actor<HttpOutboundConnection>("Connect", fd.move_as_ok(), std::numeric_limits<size_t>::max(), 0, 0,
+                                             ActorOwn<HttpOutboundConnection::Callback>(actor_id(this)));
+    yield();
+    cnt_ = 100000;
+    counter++;
+  }
+  void tear_down() override {
+    if (--counter == 0) {
+      Scheduler::instance()->finish();
+    }
+  }
+  void loop() override {
+    if (cnt_-- < 0) {
+      return stop();
+    }
+    send_closure(connection_, &HttpOutboundConnection::write_next, BufferSlice("GET / HTTP/1.1\r\n\r\n"));
+    send_closure(connection_, &HttpOutboundConnection::write_ok);
+    LOG(INFO) << "SEND";
+  }
+  void handle(HttpQueryPtr result) override {
+    loop();
+  }
+  void on_connection_error(Status error) override {
+    LOG(ERROR) << "ERROR: " << error;
+  }
+
+  ActorOwn<HttpOutboundConnection> connection_;
+  int cnt_;
+};
+
+int main() {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR));
+  auto scheduler = make_unique<ConcurrentScheduler>();
+  scheduler->init(0);
+  scheduler->create_actor_unsafe<HttpClient>(0, "Client1").release();
+  scheduler->create_actor_unsafe<HttpClient>(0, "Client2").release();
+  scheduler->start();
+  while (scheduler->run_main(10)) {
+    // empty
+  }
+  scheduler->finish();
+  return 0;
+}
+}  // namespace td
+
+int main() {
+  return td::main();
+}
diff --git a/libs/tdlib/td/benchmark/bench_http_reader.cpp b/libs/tdlib/td/benchmark/bench_http_reader.cpp
new file mode 100644
index 0000000000..2afe2d73ff
--- /dev/null
+++ b/libs/tdlib/td/benchmark/bench_http_reader.cpp
@@ -0,0 +1,118 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/net/HttpQuery.h"
+#include "td/net/HttpReader.h"
+
+#include "td/utils/benchmark.h"
+#include "td/utils/buffer.h"
+#include "td/utils/find_boundary.h"
+#include "td/utils/logging.h"
+
+static std::string http_query = "GET / HTTP/1.1\r\nConnection:keep-alive\r\nhost:127.0.0.1:8080\r\n\r\n";
+static const size_t block_size = 2500;
+
+class HttpReaderBench : public td::Benchmark {
+  std::string get_description() const override {
+    return "HttpReaderBench";
+  }
+
+  void run(int n) override {
+    int cnt = static_cast<int>(block_size / http_query.size());
+    td::HttpQuery q;
+    int parsed = 0;
+    int sent = 0;
+    for (int i = 0; i < n; i += cnt) {
+      for (int j = 0; j < cnt; j++) {
+        writer_.append(http_query);
+        sent++;
+      }
+      reader_.sync_with_writer();
+      while (true) {
+        auto wait = http_reader_.read_next(&q).ok();
+        if (wait != 0) {
+          break;
+        }
+        parsed++;
+      }
+    }
+    CHECK(parsed == sent);
+  }
+  td::ChainBufferWriter writer_;
+  td::ChainBufferReader reader_;
+  td::HttpReader http_reader_;
+
+  void start_up() override {
+    writer_ = td::ChainBufferWriter::create_empty();
+    reader_ = writer_.extract_reader();
+    http_reader_.init(&reader_, 10000, 0);
+  }
+};
+
+class BufferBench : public td::Benchmark {
+  std::string get_description() const override {
+    return "BufferBench";
+  }
+
+  void run(int n) override {
+    int cnt = static_cast<int>(block_size / http_query.size());
+    for (int i = 0; i < n; i += cnt) {
+      for (int j = 0; j < cnt; j++) {
+        writer_.append(http_query);
+      }
+      reader_.sync_with_writer();
+      for (int j = 0; j < cnt; j++) {
+        reader_.cut_head(http_query.size());
+      }
+    }
+  }
+  td::ChainBufferWriter writer_;
+  td::ChainBufferReader reader_;
+  td::HttpReader http_reader_;
+
+  void start_up() override {
+    writer_ = td::ChainBufferWriter::create_empty();
+    reader_ = writer_.extract_reader();
+  }
+};
+
+class FindBoundaryBench : public td::Benchmark {
+  std::string get_description() const override {
+    return "FindBoundaryBench";
+  }
+
+  void run(int n) override {
+    int cnt = static_cast<int>(block_size / http_query.size());
+    for (int i = 0; i < n; i += cnt) {
+      for (int j = 0; j < cnt; j++) {
+        writer_.append(http_query);
+      }
+      reader_.sync_with_writer();
+      for (int j = 0; j < cnt; j++) {
+        size_t len = 0;
+        find_boundary(reader_.clone(), "\r\n\r\n", len);
+        CHECK(size_t(len) + 4 == http_query.size());
+        reader_.cut_head(len + 2);
+        reader_.advance(2);
+      }
+    }
+  }
+  td::ChainBufferWriter writer_;
+  td::ChainBufferReader reader_;
+  td::HttpReader http_reader_;
+
+  void start_up() override {
+    writer_ = td::ChainBufferWriter::create_empty();
+    reader_ = writer_.extract_reader();
+  }
+};
+
+int main() {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(WARNING));
+  td::bench(BufferBench());
+  td::bench(FindBoundaryBench());
+  td::bench(HttpReaderBench());
+}
diff --git a/libs/tdlib/td/benchmark/bench_http_server.cpp b/libs/tdlib/td/benchmark/bench_http_server.cpp
new file mode 100644
index 0000000000..c48e8b4a67
--- /dev/null
+++ b/libs/tdlib/td/benchmark/bench_http_server.cpp
@@ -0,0 +1,89 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/actor/actor.h"
+
+#include "td/net/HttpHeaderCreator.h"
+#include "td/net/HttpInboundConnection.h"
+#include "td/net/HttpQuery.h"
+#include "td/net/TcpListener.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/SocketFd.h"
+#include "td/utils/Slice.h"
+
+namespace td {
+
+static int cnt = 0;
+class HelloWorld : public HttpInboundConnection::Callback {
+ public:
+  void handle(HttpQueryPtr query, ActorOwn<HttpInboundConnection> connection) override {
+    // LOG(ERROR) << *query;
+    HttpHeaderCreator hc;
+    Slice content = "hello world";
+    //auto content = BufferSlice("hello world");
+    hc.init_ok();
+    hc.set_keep_alive();
+    hc.set_content_size(content.size());
+    hc.add_header("Server", "TDLib/test");
+    hc.add_header("Date", "Thu Dec 14 01:41:50 2017");
+    hc.add_header("Content-Type:", "text/html");
+
+    auto res = hc.finish(content);
+    LOG_IF(FATAL, res.is_error()) << res.error();
+    send_closure(connection, &HttpInboundConnection::write_next, BufferSlice(res.ok()));
+    send_closure(connection.release(), &HttpInboundConnection::write_ok);
+  }
+  void hangup() override {
+    LOG(ERROR) << "CLOSE " << cnt--;
+    stop();
+  }
+};
+
+const int N = 0;
+class Server : public TcpListener::Callback {
+ public:
+  void start_up() override {
+    listener_ = create_actor<TcpListener>("Listener", 8082, ActorOwn<TcpListener::Callback>(actor_id(this)));
+  }
+  void accept(SocketFd fd) override {
+    LOG(ERROR) << "ACCEPT " << cnt++;
+    pos_++;
+    auto scheduler_id = pos_ % (N != 0 ? N : 1) + (N != 0);
+    create_actor_on_scheduler<HttpInboundConnection>("HttpInboundConnection", scheduler_id, std::move(fd), 1024 * 1024,
+                                                     0, 0,
+                                                     create_actor_on_scheduler<HelloWorld>("HelloWorld", scheduler_id))
+        .release();
+  }
+  void hangup() override {
+    // may be it should be default?..
+    LOG(ERROR) << "hangup..";
+    stop();
+  }
+
+ private:
+  ActorOwn<TcpListener> listener_;
+  int pos_{0};
+};
+
+int main() {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR));
+  auto scheduler = make_unique<ConcurrentScheduler>();
+  scheduler->init(N);
+  scheduler->create_actor_unsafe<Server>(0, "Server").release();
+  scheduler->start();
+  while (scheduler->run_main(10)) {
+    // empty
+  }
+  scheduler->finish();
+  return 0;
+}
+}  // namespace td
+
+int main() {
+  return td::main();
+}
diff --git a/libs/tdlib/td/benchmark/bench_http_server_cheat.cpp b/libs/tdlib/td/benchmark/bench_http_server_cheat.cpp
new file mode 100644
index 0000000000..da6fbbd713
--- /dev/null
+++ b/libs/tdlib/td/benchmark/bench_http_server_cheat.cpp
@@ -0,0 +1,138 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/actor/actor.h"
+
+#include "td/net/HttpHeaderCreator.h"
+#include "td/net/HttpInboundConnection.h"
+#include "td/net/TcpListener.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/SocketFd.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <array>
+
+namespace td {
+
+// HttpInboundConnection header
+static int cnt = 0;
+class HelloWorld : public Actor {
+ public:
+  explicit HelloWorld(SocketFd socket_fd) : socket_fd_(std::move(socket_fd)) {
+  }
+
+ private:
+  SocketFd socket_fd_;
+
+  std::array<char, 1024> read_buf;
+  size_t read_new_lines{0};
+
+  std::string hello_;
+  std::string write_buf_;
+  size_t write_pos_{0};
+
+  void start_up() override {
+    socket_fd_.get_fd().set_observer(this);
+    subscribe(socket_fd_.get_fd());
+    HttpHeaderCreator hc;
+    Slice content = "hello world";
+    //auto content = BufferSlice("hello world");
+    hc.init_ok();
+    hc.set_keep_alive();
+    hc.set_content_size(content.size());
+    hc.add_header("Server", "TDLib/test");
+    hc.add_header("Date", "Thu Dec 14 01:41:50 2017");
+    hc.add_header("Content-Type:", "text/html");
+    hello_ = hc.finish(content).ok().str();
+  }
+
+  void loop() override {
+    auto status = do_loop();
+    if (status.is_error()) {
+      unsubscribe(socket_fd_.get_fd());
+      stop();
+      LOG(ERROR) << "CLOSE: " << status;
+    }
+  }
+  Status do_loop() {
+    TRY_STATUS(read_loop());
+    TRY_STATUS(write_loop());
+    if (can_close(socket_fd_)) {
+      return Status::Error("CLOSE");
+    }
+    return Status::OK();
+  }
+  Status write_loop() {
+    while (can_write(socket_fd_) && write_pos_ < write_buf_.size()) {
+      TRY_RESULT(written, socket_fd_.write(Slice(write_buf_).substr(write_pos_)));
+      write_pos_ += written;
+      if (write_pos_ == write_buf_.size()) {
+        write_pos_ = 0;
+        write_buf_.clear();
+      }
+    }
+    return Status::OK();
+  }
+  Status read_loop() {
+    while (can_read(socket_fd_)) {
+      TRY_RESULT(read_size, socket_fd_.read(MutableSlice(read_buf.data(), read_buf.size())));
+      for (size_t i = 0; i < read_size; i++) {
+        if (read_buf[i] == '\n') {
+          read_new_lines++;
+          if (read_new_lines == 2) {
+            read_new_lines = 0;
+            write_buf_.append(hello_);
+          }
+        }
+      }
+    }
+    return Status::OK();
+  }
+};
+const int N = 0;
+class Server : public TcpListener::Callback {
+ public:
+  void start_up() override {
+    listener_ = create_actor<TcpListener>("Listener", 8082, ActorOwn<TcpListener::Callback>(actor_id(this)));
+  }
+  void accept(SocketFd fd) override {
+    LOG(ERROR) << "ACCEPT " << cnt++;
+    pos_++;
+    auto scheduler_id = pos_ % (N != 0 ? N : 1) + (N != 0);
+    create_actor_on_scheduler<HelloWorld>("HttpInboundConnection", scheduler_id, std::move(fd)).release();
+  }
+  void hangup() override {
+    // may be it should be default?..
+    LOG(ERROR) << "hangup..";
+    stop();
+  }
+
+ private:
+  ActorOwn<TcpListener> listener_;
+  int pos_{0};
+};
+
+int main() {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR));
+  auto scheduler = make_unique<ConcurrentScheduler>();
+  scheduler->init(N);
+  scheduler->create_actor_unsafe<Server>(0, "Server").release();
+  scheduler->start();
+  while (scheduler->run_main(10)) {
+    // empty
+  }
+  scheduler->finish();
+  return 0;
+}
+}  // namespace td
+
+int main() {
+  return td::main();
+}
diff --git a/libs/tdlib/td/benchmark/bench_http_server_fast.cpp b/libs/tdlib/td/benchmark/bench_http_server_fast.cpp
new file mode 100644
index 0000000000..fbda47590b
--- /dev/null
+++ b/libs/tdlib/td/benchmark/bench_http_server_fast.cpp
@@ -0,0 +1,121 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/actor/actor.h"
+
+#include "td/net/HttpHeaderCreator.h"
+#include "td/net/HttpQuery.h"
+#include "td/net/HttpReader.h"
+#include "td/net/TcpListener.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/BufferedFd.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/SocketFd.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+class HttpEchoConnection : public Actor {
+ public:
+  explicit HttpEchoConnection(SocketFd fd) : fd_(std::move(fd)) {
+  }
+
+ private:
+  BufferedFd<SocketFd> fd_;
+  HttpReader reader_;
+  HttpQuery query_;
+  void start_up() override {
+    fd_.get_fd().set_observer(this);
+    subscribe(fd_.get_fd());
+    reader_.init(&fd_.input_buffer(), 1024 * 1024, 0);
+  }
+
+  void handle_query() {
+    query_ = HttpQuery();
+    HttpHeaderCreator hc;
+    Slice content = "hello world";
+    //auto content = BufferSlice("hello world");
+    hc.init_ok();
+    hc.set_keep_alive();
+    hc.set_content_size(content.size());
+    hc.add_header("Server", "TDLib/test");
+    hc.add_header("Date", "Thu Dec 14 01:41:50 2017");
+    hc.add_header("Content-Type:", "text/html");
+    auto res = hc.finish(content);
+    fd_.output_buffer().append(res.ok());
+  }
+
+  void loop() override {
+    auto status = [&] {
+      TRY_STATUS(loop_read());
+      TRY_STATUS(loop_write());
+      return Status::OK();
+    }();
+    if (status.is_error() || can_close(fd_)) {
+      stop();
+    }
+  }
+  Status loop_read() {
+    if (can_read(fd_)) {
+      TRY_STATUS(fd_.flush_read());
+    }
+    while (true) {
+      TRY_RESULT(need, reader_.read_next(&query_));
+      if (need == 0) {
+        handle_query();
+      } else {
+        break;
+      }
+    }
+    return Status::OK();
+  }
+  Status loop_write() {
+    TRY_STATUS(fd_.flush_write());
+    return Status::OK();
+  }
+};
+
+const int N = 4;
+class Server : public TcpListener::Callback {
+ public:
+  void start_up() override {
+    listener_ = create_actor<TcpListener>("Listener", 8082, ActorOwn<TcpListener::Callback>(actor_id(this)));
+  }
+  void accept(SocketFd fd) override {
+    pos_++;
+    auto scheduler_id = pos_ % (N != 0 ? N : 1) + (N != 0);
+    create_actor_on_scheduler<HttpEchoConnection>("HttpInboundConnection", scheduler_id, std::move(fd)).release();
+  }
+  void hangup() override {
+    LOG(ERROR) << "hangup..";
+    stop();
+  }
+
+ private:
+  ActorOwn<TcpListener> listener_;
+  int pos_{0};
+};
+
+int main() {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR));
+  auto scheduler = make_unique<ConcurrentScheduler>();
+  scheduler->init(N);
+  scheduler->create_actor_unsafe<Server>(0, "Server").release();
+  scheduler->start();
+  while (scheduler->run_main(10)) {
+    // empty
+  }
+  scheduler->finish();
+  return 0;
+}
+}  // namespace td
+
+int main() {
+  return td::main();
+}
diff --git a/libs/tdlib/td/benchmark/bench_log.cpp b/libs/tdlib/td/benchmark/bench_log.cpp
new file mode 100644
index 0000000000..a57b1b9b42
--- /dev/null
+++ b/libs/tdlib/td/benchmark/bench_log.cpp
@@ -0,0 +1,163 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/benchmark.h"
+#include "td/utils/logging.h"
+
+#include <cstdio>
+#include <fstream>
+#include <iostream>
+#include <mutex>
+#include <ostream>
+#include <streambuf>
+#include <string>
+
+#include <unistd.h>
+
+std::string create_tmp_file() {
+#if TD_ANDROID
+  std::string name = "/data/local/tmp/large_file.txt";
+  unlink(name.c_str());
+  return name;
+#else
+  char file_name[] = "largefileXXXXXX";
+  int fd = mkstemp(file_name);
+  if (fd == -1) {
+    perror("Can't cretate temporary file");
+  }
+  CHECK(fd != -1);
+
+  close(fd);
+  return file_name;
+#endif
+}
+
+class IostreamWriteBench : public td::Benchmark {
+ protected:
+  std::string file_name_;
+  std::ofstream stream;
+  enum { buffer_size = 1 << 20 };
+  char buffer[buffer_size];
+
+ public:
+  std::string get_description() const override {
+    return "ostream (to file, no buf, no flush)";
+  }
+
+  void start_up() override {
+    file_name_ = create_tmp_file();
+    stream.open(file_name_.c_str());
+    CHECK(stream.is_open());
+    //    stream.rdbuf()->pubsetbuf(buffer, buffer_size);
+  }
+
+  void run(int n) override {
+    for (int i = 0; i < n; i++) {
+      stream << "This is just for test" << 987654321 << '\n';
+    }
+  }
+
+  void tear_down() override {
+    stream.close();
+    unlink(file_name_.c_str());
+  }
+};
+
+class FILEWriteBench : public td::Benchmark {
+ protected:
+  std::string file_name_;
+  FILE *file;
+  enum { buffer_size = 1 << 20 };
+  char buffer[buffer_size];
+
+ public:
+  std::string get_description() const override {
+    return "std::fprintf (to file, no buf, no flush)";
+  }
+
+  void start_up() override {
+    file_name_ = create_tmp_file();
+    file = fopen(file_name_.c_str(), "w");
+    //    setvbuf(file, buffer, _IOFBF, buffer_size);
+  }
+
+  void run(int n) override {
+    for (int i = 0; i < n; i++) {
+      std::fprintf(file, "This is just for test%d\n", 987654321);
+      //      std::fflush(file);
+    }
+  }
+
+  void tear_down() override {
+    std::fclose(file);
+    unlink(file_name_.c_str());
+  }
+};
+
+#if TD_ANDROID
+#include <android/log.h>
+#define ALOG(...) __android_log_print(ANDROID_LOG_VERBOSE, "XXX", __VA_ARGS__)
+class ALogWriteBench : public td::Benchmark {
+ public:
+  std::string get_description() const override {
+    return "android_log";
+  }
+  void start_up() override {
+  }
+  void run(int n) override {
+    for (int i = 0; i < n; i++) {
+      ALOG("This is just for test%d\n", 987654321);
+    }
+  }
+  void tear_down() override {
+  }
+};
+#endif
+
+class LogWriteBench : public td::Benchmark {
+ protected:
+  std::string file_name_;
+  std::ofstream stream;
+  std::streambuf *old_buf;
+  enum { buffer_size = 1 << 20 };
+  char buffer[buffer_size];
+
+ public:
+  std::string get_description() const override {
+    return "td_log (slow in debug mode)";
+  }
+
+  void start_up() override {
+    file_name_ = create_tmp_file();
+    stream.open(file_name_.c_str());
+    CHECK(stream.is_open());
+    old_buf = std::cerr.rdbuf(stream.rdbuf());
+  }
+
+  void run(int n) override {
+    for (int i = 0; i < n; i++) {
+      LOG(DEBUG) << "This is just for test" << 987654321;
+    }
+  }
+
+  void tear_down() override {
+    stream.close();
+    unlink(file_name_.c_str());
+    std::cerr.rdbuf(old_buf);
+  }
+};
+
+std::mutex mutex;
+
+int main() {
+  td::bench(LogWriteBench());
+#if TD_ANDROID
+  td::bench(ALogWriteBench());
+#endif
+  td::bench(IostreamWriteBench());
+  td::bench(FILEWriteBench());
+  return 0;
+}
diff --git a/libs/tdlib/td/benchmark/bench_misc.cpp b/libs/tdlib/td/benchmark/bench_misc.cpp
new file mode 100644
index 0000000000..bfbcea438b
--- /dev/null
+++ b/libs/tdlib/td/benchmark/bench_misc.cpp
@@ -0,0 +1,392 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/benchmark.h"
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/Clocks.h"
+#include "td/utils/port/EventFd.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/port/path.h"
+#include "td/utils/port/RwMutex.h"
+#include "td/utils/port/Stat.h"
+#include "td/utils/port/thread.h"
+#include "td/utils/Slice.h"
+
+#include "td/telegram/telegram_api.h"
+#include "td/telegram/telegram_api.hpp"
+
+#if !TD_WINDOWS
+#include <unistd.h>
+#include <utime.h>
+#endif
+
+#if TD_LINUX || TD_ANDROID || TD_TIZEN
+#include <semaphore.h>
+#endif
+
+#include <atomic>
+#include <cstdint>
+
+namespace td {
+
+class F {
+  uint32 &sum;
+
+ public:
+  explicit F(uint32 &sum) : sum(sum) {
+  }
+
+  template <class T>
+  void operator()(const T &x) const {
+    sum += static_cast<uint32>(x.get_id());
+  }
+};
+
+BENCH(Call, "TL Call") {
+  tl_object_ptr<telegram_api::Function> x = make_tl_object<telegram_api::account_getWallPapers>();
+  uint32 res = 0;
+  F f(res);
+  for (int i = 0; i < n; i++) {
+    downcast_call(*x, f);
+  }
+  do_not_optimize_away(res);
+}
+
+#if !TD_EVENTFD_UNSUPPORTED
+BENCH(EventFd, "EventFd") {
+  EventFd fd;
+  fd.init();
+  for (int i = 0; i < n; i++) {
+    fd.release();
+    fd.acquire();
+  }
+  fd.close();
+}
+#endif
+
+BENCH(NewInt, "new int + delete") {
+  std::uintptr_t res = 0;
+  for (int i = 0; i < n; i++) {
+    int *x = new int;
+    res += reinterpret_cast<std::uintptr_t>(x);
+    delete x;
+  }
+  do_not_optimize_away(res);
+}
+
+BENCH(NewObj, "new struct then delete") {
+  struct A {
+    int32 a = 0;
+    int32 b = 0;
+    int32 c = 0;
+    int32 d = 0;
+  };
+  std::uintptr_t res = 0;
+  A **ptr = new A *[n];
+  for (int i = 0; i < n; i++) {
+    ptr[i] = new A();
+    res += reinterpret_cast<std::uintptr_t>(ptr[i]);
+  }
+  for (int i = 0; i < n; i++) {
+    delete ptr[i];
+  }
+  delete[] ptr;
+  do_not_optimize_away(res);
+}
+
+#if !TD_THREAD_UNSUPPORTED
+BENCH(ThreadNew, "new struct then delete in several threads") {
+  td::NewObjBench a, b;
+  thread ta([&] { a.run(n / 2); });
+  thread tb([&] { b.run(n - n / 2); });
+  ta.join();
+  tb.join();
+}
+#endif
+
+// Too hard for android clang (?)
+BENCH(Time, "Clocks::monotonic") {
+  double res = 0;
+  for (int i = 0; i < n; i++) {
+    res += Clocks::monotonic();
+  }
+  do_not_optimize_away(res);
+}
+
+#if !TD_WINDOWS
+class PipeBench : public Benchmark {
+ public:
+  int p[2];
+
+  PipeBench() {
+    pipe(p);
+  }
+
+  string get_description() const override {
+    return "pipe write + read int32";
+  }
+
+  void start_up() override {
+    pipe(p);
+  }
+
+  void run(int n) override {
+    int res = 0;
+    for (int i = 0; i < n; i++) {
+      int val = 1;
+      write(p[1], &val, sizeof(val));
+      read(p[0], &val, sizeof(val));
+      res += val;
+    }
+    do_not_optimize_away(res);
+  }
+
+  void tear_down() override {
+    close(p[0]);
+    close(p[1]);
+  }
+};
+#endif
+
+#if TD_LINUX || TD_ANDROID || TD_TIZEN
+class SemBench : public Benchmark {
+  sem_t sem;
+
+ public:
+  string get_description() const override {
+    return "sem post + wait";
+  }
+
+  void start_up() override {
+    int err = sem_init(&sem, 0, 0);
+    CHECK(err != -1);
+  }
+
+  void run(int n) override {
+    for (int i = 0; i < n; i++) {
+      sem_post(&sem);
+      sem_wait(&sem);
+    }
+  }
+
+  void tear_down() override {
+    sem_destroy(&sem);
+  }
+};
+#endif
+
+#if !TD_WINDOWS
+class UtimeBench : public Benchmark {
+ public:
+  void start_up() override {
+    FileFd::open("test", FileFd::Flags::Create | FileFd::Flags::Write).move_as_ok().close();
+  }
+  string get_description() const override {
+    return "utime";
+  }
+  void run(int n) override {
+    for (int i = 0; i < n; i++) {
+      int err = utime("test", nullptr);
+      CHECK(err >= 0);
+      utimbuf buf;
+      buf.modtime = 123;
+      buf.actime = 321;
+      err = utime("test", &buf);
+      CHECK(err >= 0);
+    }
+  }
+};
+#endif
+
+BENCH(Pwrite, "pwrite") {
+  auto fd = FileFd::open("test", FileFd::Flags::Create | FileFd::Flags::Write).move_as_ok();
+  for (int i = 0; i < n; i++) {
+    fd.pwrite("a", 0).ok();
+  }
+  fd.close();
+}
+
+class CreateFileBench : public Benchmark {
+  string get_description() const override {
+    return "create_file";
+  }
+  void start_up() override {
+    mkdir("A").ensure();
+  }
+  void run(int n) override {
+    for (int i = 0; i < n; i++) {
+      FileFd::open("A/" + to_string(i), FileFd::Flags::Write | FileFd::Flags::Create).move_as_ok().close();
+    }
+  }
+  void tear_down() override {
+    auto status = td::walk_path("A/", [&](CSlice path, bool is_dir) {
+      if (is_dir) {
+        rmdir(path).ignore();
+      } else {
+        unlink(path).ignore();
+      }
+    });
+  }
+};
+class WalkPathBench : public Benchmark {
+  string get_description() const override {
+    return "walk_path";
+  }
+  void start_up_n(int n) override {
+    mkdir("A").ensure();
+    for (int i = 0; i < n; i++) {
+      FileFd::open("A/" + to_string(i), FileFd::Flags::Write | FileFd::Flags::Create).move_as_ok().close();
+    }
+  }
+  void run(int n) override {
+    int cnt = 0;
+    auto status = td::walk_path("A/", [&](CSlice path, bool is_dir) {
+      stat(path).ok();
+      cnt++;
+    });
+  }
+  void tear_down() override {
+    auto status = td::walk_path("A/", [&](CSlice path, bool is_dir) {
+      if (is_dir) {
+        rmdir(path).ignore();
+      } else {
+        unlink(path).ignore();
+      }
+    });
+  }
+};
+
+#if !TD_THREAD_UNSUPPORTED
+template <int ThreadN = 2>
+class AtomicReleaseIncBench : public Benchmark {
+  string get_description() const override {
+    return PSTRING() << "AtomicReleaseInc" << ThreadN;
+  }
+
+  static std::atomic<uint64> a_;
+  void run(int n) override {
+    std::vector<thread> threads;
+    for (int i = 0; i < ThreadN; i++) {
+      threads.emplace_back([&] {
+        for (int i = 0; i < n / ThreadN; i++) {
+          a_.fetch_add(1, std::memory_order_release);
+        }
+      });
+    }
+    for (auto &thread : threads) {
+      thread.join();
+    }
+  }
+};
+template <int ThreadN>
+std::atomic<uint64> AtomicReleaseIncBench<ThreadN>::a_;
+
+template <int ThreadN = 2>
+class AtomicReleaseCasIncBench : public Benchmark {
+  string get_description() const override {
+    return PSTRING() << "AtomicReleaseCasInc" << ThreadN;
+  }
+
+  static std::atomic<uint64> a_;
+  void run(int n) override {
+    std::vector<thread> threads;
+    for (int i = 0; i < ThreadN; i++) {
+      threads.emplace_back([&] {
+        for (int i = 0; i < n / ThreadN; i++) {
+          auto value = a_.load(std::memory_order_relaxed);
+          while (!a_.compare_exchange_strong(value, value + 1, std::memory_order_release, std::memory_order_relaxed)) {
+          }
+        }
+      });
+    }
+    for (auto &thread : threads) {
+      thread.join();
+    }
+  }
+};
+template <int ThreadN>
+std::atomic<uint64> AtomicReleaseCasIncBench<ThreadN>::a_;
+
+template <int ThreadN = 2>
+class RwMutexReadBench : public Benchmark {
+  string get_description() const override {
+    return PSTRING() << "RwMutexRead" << ThreadN;
+  }
+  RwMutex mutex_;
+  void run(int n) override {
+    std::vector<thread> threads;
+    for (int i = 0; i < ThreadN; i++) {
+      threads.emplace_back([&] {
+        for (int i = 0; i < n / ThreadN; i++) {
+          mutex_.lock_read().ensure();
+        }
+      });
+    }
+    for (auto &thread : threads) {
+      thread.join();
+    }
+  }
+};
+template <int ThreadN = 2>
+class RwMutexWriteBench : public Benchmark {
+  string get_description() const override {
+    return PSTRING() << "RwMutexWrite" << ThreadN;
+  }
+  RwMutex mutex_;
+  void run(int n) override {
+    std::vector<thread> threads;
+    for (int i = 0; i < ThreadN; i++) {
+      threads.emplace_back([&] {
+        for (int i = 0; i < n / ThreadN; i++) {
+          mutex_.lock_write().ensure();
+        }
+      });
+    }
+    for (auto &thread : threads) {
+      thread.join();
+    }
+  }
+};
+#endif
+}  // namespace td
+
+int main() {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(DEBUG));
+#if !TD_THREAD_UNSUPPORTED
+  td::bench(td::AtomicReleaseIncBench<1>());
+  td::bench(td::AtomicReleaseIncBench<2>());
+  td::bench(td::AtomicReleaseCasIncBench<1>());
+  td::bench(td::AtomicReleaseCasIncBench<2>());
+  td::bench(td::RwMutexWriteBench<1>());
+  td::bench(td::RwMutexReadBench<1>());
+  td::bench(td::RwMutexWriteBench<>());
+  td::bench(td::RwMutexReadBench<>());
+#endif
+#if !TD_WINDOWS
+  td::bench(td::UtimeBench());
+#endif
+  td::bench(td::WalkPathBench());
+  td::bench(td::CreateFileBench());
+  td::bench(td::PwriteBench());
+
+  td::bench(td::CallBench());
+#if !TD_THREAD_UNSUPPORTED
+  td::bench(td::ThreadNewBench());
+#endif
+#if !TD_EVENTFD_UNSUPPORTED
+  td::bench(td::EventFdBench());
+#endif
+  td::bench(td::NewObjBench());
+  td::bench(td::NewIntBench());
+#if !TD_WINDOWS
+  td::bench(td::PipeBench());
+#endif
+#if TD_LINUX || TD_ANDROID || TD_TIZEN
+  td::bench(td::SemBench());
+#endif
+  return 0;
+}
diff --git a/libs/tdlib/td/benchmark/bench_queue.cpp b/libs/tdlib/td/benchmark/bench_queue.cpp
new file mode 100644
index 0000000000..13288e6cd7
--- /dev/null
+++ b/libs/tdlib/td/benchmark/bench_queue.cpp
@@ -0,0 +1,943 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/benchmark.h"
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/MpscPollableQueue.h"
+#include "td/utils/queue.h"
+
+// TODO: check system calls
+// TODO: all return values must be checked
+
+#include <atomic>
+#include <cstdio>
+#include <cstdlib>
+#include <vector>
+
+#include <pthread.h>
+#include <sched.h>
+#include <semaphore.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#if TD_LINUX
+#include <sys/eventfd.h>
+#endif
+
+using std::atomic;
+using std::vector;
+
+using td::int32;
+using td::uint32;
+
+#define MODE std::memory_order_relaxed
+
+// void set_affinity(int mask) {
+// int err, syscallres;
+// pid_t pid = gettid();
+// syscallres = syscall(__NR_sched_setaffinity, pid, sizeof(mask), &mask);
+// if (syscallres) {
+// err = errno;
+// perror("oppa");
+//}
+//}
+
+// TODO: warnings and asserts. There should be no warnings or debug output in production.
+using qvalue_t = int;
+
+// Just for testing, not production
+class PipeQueue {
+  int input;
+  int output;
+
+ public:
+  void init() {
+    int new_pipe[2];
+    pipe(new_pipe);
+    output = new_pipe[0];
+    input = new_pipe[1];
+  }
+
+  void put(qvalue_t value) {
+    write(input, &value, sizeof(value));
+  }
+
+  qvalue_t get() {
+    qvalue_t res;
+    read(output, &res, sizeof(res));
+    return res;
+  }
+
+  void destroy() {
+    close(input);
+    close(output);
+  }
+};
+
+class Backoff {
+  int cnt;
+
+ public:
+  Backoff() : cnt(0) {
+  }
+
+  bool next() {
+    cnt++;
+    if (cnt < 50) {
+      return true;
+    } else {
+      sched_yield();
+      return cnt < 500;
+    }
+  }
+};
+
+class VarQueue {
+  atomic<qvalue_t> data;
+
+ public:
+  void init() {
+    data.store(-1, MODE);
+  }
+
+  void put(qvalue_t value) {
+    data.store(value, MODE);
+  }
+
+  qvalue_t try_get() {
+    __sync_synchronize();  // TODO: it is wrong place for barrier, but it results in fastest queue
+    qvalue_t res = data.load(MODE);
+    return res;
+  }
+
+  void acquire() {
+    data.store(-1, MODE);
+  }
+
+  qvalue_t get() {
+    qvalue_t res;
+    Backoff backoff;
+
+    do {
+      res = try_get();
+    } while (res == -1 && (backoff.next(), true));
+    acquire();
+
+    return res;
+  }
+
+  void destroy() {
+  }
+};
+
+class SemQueue {
+  sem_t sem;
+  VarQueue q;
+
+ public:
+  void init() {
+    q.init();
+    sem_init(&sem, 0, 0);
+  }
+
+  void put(qvalue_t value) {
+    q.put(value);
+    sem_post(&sem);
+  }
+
+  qvalue_t get() {
+    sem_wait(&sem);
+    qvalue_t res = q.get();
+    return res;
+  }
+
+  void destroy() {
+    q.destroy();
+    sem_destroy(&sem);
+  }
+
+  // HACK for benchmark
+  void reader_flush() {
+  }
+
+  void writer_flush() {
+  }
+
+  void writer_put(qvalue_t value) {
+    put(value);
+  }
+
+  int reader_wait() {
+    return 1;
+  }
+
+  qvalue_t reader_get_unsafe() {
+    return get();
+  }
+};
+
+#if TD_LINUX
+class EventfdQueue {
+  int fd;
+  VarQueue q;
+
+ public:
+  void init() {
+    q.init();
+    fd = eventfd(0, 0);
+  }
+  void put(qvalue_t value) {
+    q.put(value);
+    td::int64 x = 1;
+    write(fd, &x, sizeof(x));
+  }
+  qvalue_t get() {
+    td::int64 x;
+    read(fd, &x, sizeof(x));
+    return q.get();
+  }
+  void destroy() {
+    q.destroy();
+    close(fd);
+  }
+};
+#endif
+
+const int queue_buf_size = 1 << 10;
+
+class BufferQueue {
+  struct node {
+    qvalue_t val;
+    char pad[64 - sizeof(atomic<qvalue_t>)];
+  };
+  node q[queue_buf_size];
+
+  struct Position {
+    atomic<uint32> i;
+    char pad[64 - sizeof(atomic<uint32>)];
+
+    uint32 local_read_i;
+    uint32 local_write_i;
+    char pad2[64 - sizeof(uint32) * 2];
+
+    void init() {
+      i = 0;
+      local_read_i = 0;
+      local_write_i = 0;
+    }
+  };
+
+  Position writer;
+  Position reader;
+
+ public:
+  void init() {
+    writer.init();
+    reader.init();
+  }
+
+  bool reader_empty() {
+    return reader.local_write_i == reader.local_read_i;
+  }
+
+  bool writer_empty() {
+    return writer.local_write_i == writer.local_read_i + queue_buf_size;
+  }
+
+  int reader_ready() {
+    return static_cast<int>(reader.local_write_i - reader.local_read_i);
+  }
+
+  int writer_ready() {
+    return static_cast<int>(writer.local_read_i + queue_buf_size - writer.local_write_i);
+  }
+
+  qvalue_t get_unsafe() {
+    return q[reader.local_read_i++ & (queue_buf_size - 1)].val;
+  }
+
+  void flush_reader() {
+    reader.i.store(reader.local_read_i, std::memory_order_release);
+  }
+
+  int update_reader() {
+    reader.local_write_i = writer.i.load(std::memory_order_acquire);
+    return reader_ready();
+  }
+
+  void put_unsafe(qvalue_t val) {
+    q[writer.local_write_i++ & (queue_buf_size - 1)].val = val;
+  }
+
+  void flush_writer() {
+    writer.i.store(writer.local_write_i, std::memory_order_release);
+  }
+
+  int update_writer() {
+    writer.local_read_i = reader.i.load(std::memory_order_acquire);
+    return writer_ready();
+  }
+
+  int wait_reader() {
+    Backoff backoff;
+    int res = 0;
+    while (res == 0) {
+      backoff.next();
+      res = update_reader();
+    }
+    return res;
+  }
+
+  qvalue_t get_noflush() {
+    if (!reader_empty()) {
+      return get_unsafe();
+    }
+
+    Backoff backoff;
+    while (true) {
+      backoff.next();
+      if (update_reader()) {
+        return get_unsafe();
+      }
+    }
+  }
+
+  qvalue_t get() {
+    qvalue_t res = get_noflush();
+    flush_reader();
+    return res;
+  }
+
+  void put_noflush(qvalue_t val) {
+    if (!writer_empty()) {
+      put_unsafe(val);
+      return;
+    }
+    if (!update_writer()) {
+      std::fprintf(stderr, "put strong failed\n");
+      std::exit(0);
+    }
+    put_unsafe(val);
+  }
+
+  void put(qvalue_t val) {
+    put_noflush(val);
+    flush_writer();
+  }
+
+  void destroy() {
+  }
+};
+
+#if TD_LINUX
+class BufferedFdQueue {
+  int fd;
+  atomic<int> wait_flag;
+  BufferQueue q;
+  char pad[64];
+
+ public:
+  void init() {
+    q.init();
+    fd = eventfd(0, 0);
+    (void)pad[0];
+  }
+  void put(qvalue_t value) {
+    q.put(value);
+    td::int64 x = 1;
+    __sync_synchronize();
+    if (wait_flag.load(MODE)) {
+      write(fd, &x, sizeof(x));
+    }
+  }
+  void put_noflush(qvalue_t value) {
+    q.put_noflush(value);
+  }
+  void flush_writer() {
+    q.flush_writer();
+    td::int64 x = 1;
+    __sync_synchronize();
+    if (wait_flag.load(MODE)) {
+      write(fd, &x, sizeof(x));
+    }
+  }
+  void flush_reader() {
+    q.flush_reader();
+  }
+
+  qvalue_t get_unsafe_flush() {
+    qvalue_t res = q.get_unsafe();
+    q.flush_reader();
+    return res;
+  }
+
+  qvalue_t get_unsafe() {
+    return q.get_unsafe();
+  }
+
+  int wait_reader() {
+    int res = 0;
+    Backoff backoff;
+    while (res == 0 && backoff.next()) {
+      res = q.update_reader();
+    }
+    if (res != 0) {
+      return res;
+    }
+
+    td::int64 x;
+    wait_flag.store(1, MODE);
+    __sync_synchronize();
+    while (!(res = q.update_reader())) {
+      read(fd, &x, sizeof(x));
+      __sync_synchronize();
+    }
+    wait_flag.store(0, MODE);
+    return res;
+  }
+
+  qvalue_t get() {
+    if (!q.reader_empty()) {
+      return get_unsafe_flush();
+    }
+
+    Backoff backoff;
+    while (backoff.next()) {
+      if (q.update_reader()) {
+        return get_unsafe_flush();
+      }
+    }
+
+    td::int64 x;
+    wait_flag.store(1, MODE);
+    __sync_synchronize();
+    while (!q.update_reader()) {
+      read(fd, &x, sizeof(x));
+      __sync_synchronize();
+    }
+    wait_flag.store(0, MODE);
+    return get_unsafe_flush();
+  }
+  void destroy() {
+    q.destroy();
+    close(fd);
+  }
+};
+
+class FdQueue {
+  int fd;
+  atomic<int> wait_flag;
+  VarQueue q;
+  char pad[64];
+
+ public:
+  void init() {
+    q.init();
+    fd = eventfd(0, 0);
+    (void)pad[0];
+  }
+  void put(qvalue_t value) {
+    q.put(value);
+    td::int64 x = 1;
+    __sync_synchronize();
+    if (wait_flag.load(MODE)) {
+      write(fd, &x, sizeof(x));
+    }
+  }
+  qvalue_t get() {
+    // td::int64 x;
+    // read(fd, &x, sizeof(x));
+    // return q.get();
+
+    Backoff backoff;
+    qvalue_t res = -1;
+    do {
+      res = q.try_get();
+    } while (res == -1 && backoff.next());
+    if (res != -1) {
+      q.acquire();
+      return res;
+    }
+
+    td::int64 x;
+    wait_flag.store(1, MODE);
+    __sync_synchronize();
+    // std::fprintf(stderr, "!\n");
+    // while (res == -1 && read(fd, &x, sizeof(x))) {
+    // res = q.try_get();
+    //}
+    do {
+      __sync_synchronize();
+      res = q.try_get();
+    } while (res == -1 && read(fd, &x, sizeof(x)));
+    q.acquire();
+    wait_flag.store(0, MODE);
+    return res;
+  }
+  void destroy() {
+    q.destroy();
+    close(fd);
+  }
+};
+#endif
+
+class SemBackoffQueue {
+  sem_t sem;
+  VarQueue q;
+
+ public:
+  void init() {
+    q.init();
+    sem_init(&sem, 0, 0);
+  }
+
+  void put(qvalue_t value) {
+    q.put(value);
+    sem_post(&sem);
+  }
+
+  qvalue_t get() {
+    Backoff backoff;
+    int sem_flag = -1;
+    do {
+      sem_flag = sem_trywait(&sem);
+    } while (sem_flag != 0 && backoff.next());
+    if (sem_flag != 0) {
+      sem_wait(&sem);
+    }
+    return q.get();
+  }
+
+  void destroy() {
+    q.destroy();
+    sem_destroy(&sem);
+  }
+};
+
+class SemCheatQueue {
+  sem_t sem;
+  VarQueue q;
+
+ public:
+  void init() {
+    q.init();
+    sem_init(&sem, 0, 0);
+  }
+
+  void put(qvalue_t value) {
+    q.put(value);
+    sem_post(&sem);
+  }
+
+  qvalue_t get() {
+    Backoff backoff;
+    qvalue_t res = -1;
+    do {
+      res = q.try_get();
+    } while (res == -1 && backoff.next());
+    sem_wait(&sem);
+    if (res != -1) {
+      q.acquire();
+      return res;
+    }
+    return q.get();
+  }
+
+  void destroy() {
+    q.destroy();
+    sem_destroy(&sem);
+  }
+};
+
+template <class QueueT>
+class QueueBenchmark2 : public td::Benchmark {
+  QueueT client, server;
+  int connections_n, queries_n;
+
+  int server_active_connections;
+  int client_active_connections;
+  vector<td::int64> server_conn;
+  vector<td::int64> client_conn;
+
+ public:
+  explicit QueueBenchmark2(int connections_n = 1) : connections_n(connections_n) {
+  }
+
+  std::string get_description() const override {
+    return "QueueBenchmark2";
+  }
+
+  void start_up() override {
+    client.init();
+    server.init();
+  }
+
+  void tear_down() override {
+    client.destroy();
+    server.destroy();
+  }
+
+  void server_process(qvalue_t value) {
+    int no = value & 0x00FFFFFF;
+    int co = static_cast<int>(static_cast<unsigned int>(value) >> 24);
+    // std::fprintf(stderr, "-->%d %d\n", co, no);
+    if (co < 0 || co >= connections_n || no != server_conn[co]++) {
+      std::fprintf(stderr, "%d %d\n", co, no);
+      std::fprintf(stderr, "expected %d %lld\n", co, static_cast<long long>(server_conn[co] - 1));
+      std::fprintf(stderr, "Server BUG\n");
+      while (true) {
+      }
+    }
+    // std::fprintf(stderr, "no = %d/%d\n", no, queries_n);
+    // std::fprintf(stderr, "answer: %d %d\n", no, co);
+
+    client.writer_put(value);
+    client.writer_flush();
+    if (no + 1 >= queries_n) {
+      server_active_connections--;
+    }
+  }
+
+  void *server_run(void *) {
+    server_conn = vector<td::int64>(connections_n);
+    server_active_connections = connections_n;
+
+    while (server_active_connections > 0) {
+      int cnt = server.reader_wait();
+      if (cnt == 0) {
+        std::fprintf(stderr, "ERROR!\n");
+        std::exit(0);
+      }
+      while (cnt-- > 0) {
+        server_process(server.reader_get_unsafe());
+        server.reader_flush();
+      }
+      // client.writer_flush();
+      server.reader_flush();
+    }
+    return nullptr;
+  }
+
+  void client_process(qvalue_t value) {
+    int no = value & 0x00FFFFFF;
+    int co = static_cast<int>(static_cast<unsigned int>(value) >> 24);
+    // std::fprintf(stderr, "<--%d %d\n", co, no);
+    if (co < 0 || co >= connections_n || no != client_conn[co]++) {
+      std::fprintf(stderr, "%d %d\n", co, no);
+      std::fprintf(stderr, "expected %d %lld\n", co, static_cast<long long>(client_conn[co] - 1));
+      std::fprintf(stderr, "BUG\n");
+      while (true) {
+      }
+      std::exit(0);
+    }
+    if (no + 1 < queries_n) {
+      // std::fprintf(stderr, "query: %d %d\n", no + 1, co);
+      server.writer_put(value + 1);
+      server.writer_flush();
+    } else {
+      client_active_connections--;
+    }
+  }
+
+  void *client_run(void *) {
+    client_conn = vector<td::int64>(connections_n);
+    client_active_connections = connections_n;
+    if (queries_n >= (1 << 24)) {
+      std::fprintf(stderr, "Too big queries_n\n");
+      std::exit(0);
+    }
+
+    for (int i = 0; i < connections_n; i++) {
+      server.writer_put(static_cast<qvalue_t>(i) << 24);
+    }
+    server.writer_flush();
+
+    while (client_active_connections > 0) {
+      int cnt = client.reader_wait();
+      if (cnt == 0) {
+        std::fprintf(stderr, "ERROR!\n");
+        std::exit(0);
+      }
+      while (cnt-- > 0) {
+        client_process(client.reader_get_unsafe());
+        client.reader_flush();
+      }
+      // server.writer_flush();
+      client.reader_flush();
+    }
+    // system("cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq");
+    return nullptr;
+  }
+
+  static void *client_run_gateway(void *arg) {
+    return static_cast<QueueBenchmark2 *>(arg)->client_run(nullptr);
+  }
+
+  static void *server_run_gateway(void *arg) {
+    return static_cast<QueueBenchmark2 *>(arg)->server_run(nullptr);
+  }
+
+  void run(int n) override {
+    pthread_t client_thread_id;
+    pthread_t server_thread_id;
+
+    queries_n = (n + connections_n - 1) / connections_n;
+
+    pthread_create(&client_thread_id, nullptr, client_run_gateway, this);
+    pthread_create(&server_thread_id, nullptr, server_run_gateway, this);
+
+    pthread_join(client_thread_id, nullptr);
+    pthread_join(server_thread_id, nullptr);
+  }
+};
+
+template <class QueueT>
+class QueueBenchmark : public td::Benchmark {
+  QueueT client, server;
+  const int connections_n;
+  int queries_n;
+
+ public:
+  explicit QueueBenchmark(int connections_n = 1) : connections_n(connections_n) {
+  }
+
+  std::string get_description() const override {
+    return "QueueBenchmark";
+  }
+
+  void start_up() override {
+    client.init();
+    server.init();
+  }
+
+  void tear_down() override {
+    client.destroy();
+    server.destroy();
+  }
+
+  void *server_run(void *) {
+    vector<td::int64> conn(connections_n);
+    int active_connections = connections_n;
+    while (active_connections > 0) {
+      qvalue_t value = server.get();
+      int no = value & 0x00FFFFFF;
+      int co = static_cast<int>(value >> 24);
+      // std::fprintf(stderr, "-->%d %d\n", co, no);
+      if (co < 0 || co >= connections_n || no != conn[co]++) {
+        std::fprintf(stderr, "%d %d\n", co, no);
+        std::fprintf(stderr, "expected %d %lld\n", co, static_cast<long long>(conn[co] - 1));
+        std::fprintf(stderr, "Server BUG\n");
+        while (true) {
+        }
+      }
+      // std::fprintf(stderr, "no = %d/%d\n", no, queries_n);
+      client.put(value);
+      if (no + 1 >= queries_n) {
+        active_connections--;
+      }
+    }
+    return nullptr;
+  }
+
+  void *client_run(void *) {
+    vector<td::int64> conn(connections_n);
+    if (queries_n >= (1 << 24)) {
+      std::fprintf(stderr, "Too big queries_n\n");
+      std::exit(0);
+    }
+    for (int i = 0; i < connections_n; i++) {
+      server.put(static_cast<qvalue_t>(i) << 24);
+    }
+    int active_connections = connections_n;
+    while (active_connections > 0) {
+      qvalue_t value = client.get();
+      int no = value & 0x00FFFFFF;
+      int co = static_cast<int>(value >> 24);
+      // std::fprintf(stderr, "<--%d %d\n", co, no);
+      if (co < 0 || co >= connections_n || no != conn[co]++) {
+        std::fprintf(stderr, "%d %d\n", co, no);
+        std::fprintf(stderr, "expected %d %lld\n", co, static_cast<long long>(conn[co] - 1));
+        std::fprintf(stderr, "BUG\n");
+        while (true) {
+        }
+        std::exit(0);
+      }
+      if (no + 1 < queries_n) {
+        server.put(value + 1);
+      } else {
+        active_connections--;
+      }
+    }
+    // system("cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq");
+    return nullptr;
+  }
+
+  void *client_run2(void *) {
+    vector<td::int64> conn(connections_n);
+    if (queries_n >= (1 << 24)) {
+      std::fprintf(stderr, "Too big queries_n\n");
+      std::exit(0);
+    }
+    for (int it = 0; it < queries_n; it++) {
+      for (int i = 0; i < connections_n; i++) {
+        server.put((static_cast<td::int64>(i) << 24) + it);
+      }
+      for (int i = 0; i < connections_n; i++) {
+        qvalue_t value = client.get();
+        int no = value & 0x00FFFFFF;
+        int co = static_cast<int>(value >> 24);
+        // std::fprintf(stderr, "<--%d %d\n", co, no);
+        if (co < 0 || co >= connections_n || no != conn[co]++) {
+          std::fprintf(stderr, "%d %d\n", co, no);
+          std::fprintf(stderr, "expected %d %lld\n", co, static_cast<long long>(conn[co] - 1));
+          std::fprintf(stderr, "BUG\n");
+          while (true) {
+          }
+          std::exit(0);
+        }
+      }
+    }
+    // system("cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq");
+    return nullptr;
+  }
+
+  static void *client_run_gateway(void *arg) {
+    return static_cast<QueueBenchmark *>(arg)->client_run(nullptr);
+  }
+
+  static void *server_run_gateway(void *arg) {
+    return static_cast<QueueBenchmark *>(arg)->server_run(nullptr);
+  }
+
+  void run(int n) override {
+    pthread_t client_thread_id;
+    pthread_t server_thread_id;
+
+    queries_n = (n + connections_n - 1) / connections_n;
+
+    pthread_create(&client_thread_id, nullptr, client_run_gateway, this);
+    pthread_create(&server_thread_id, nullptr, server_run_gateway, this);
+
+    pthread_join(client_thread_id, nullptr);
+    pthread_join(server_thread_id, nullptr);
+  }
+};
+
+template <class QueueT>
+class RingBenchmark : public td::Benchmark {
+  enum { QN = 504 };
+
+  struct Thread {
+    int int_id;
+    pthread_t id;
+    QueueT queue;
+    Thread *next;
+    char pad[64];
+
+    void *run() {
+      qvalue_t value;
+      // std::fprintf(stderr, "start %d\n", int_id);
+      do {
+        int cnt = queue.reader_wait();
+        CHECK(cnt == 1);
+        value = queue.reader_get_unsafe();
+        queue.reader_flush();
+
+        next->queue.writer_put(value - 1);
+        next->queue.writer_flush();
+      } while (value >= QN);
+      return nullptr;
+    }
+  };
+
+  Thread q[QN];
+
+ public:
+  static void *run_gateway(void *arg) {
+    return static_cast<Thread *>(arg)->run();
+  }
+
+  void start_up() override {
+    for (int i = 0; i < QN; i++) {
+      q[i].int_id = i;
+      q[i].queue.init();
+      q[i].next = &q[(i + 1) % QN];
+    }
+  }
+
+  void tear_down() override {
+    for (int i = 0; i < QN; i++) {
+      q[i].queue.destroy();
+    }
+  }
+
+  void run(int n) override {
+    for (int i = 0; i < QN; i++) {
+      pthread_create(&q[i].id, nullptr, run_gateway, &q[i]);
+    }
+
+    std::fprintf(stderr, "run %d\n", n);
+    if (n < 1000) {
+      n = 1000;
+    }
+    q[0].queue.writer_put(n);
+    q[0].queue.writer_flush();
+
+    for (int i = 0; i < QN; i++) {
+      pthread_join(q[i].id, nullptr);
+    }
+  }
+};
+
+int main() {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(DEBUG));
+#define BENCH_Q2(Q, N)                      \
+  std::fprintf(stderr, "!%s %d:\t", #Q, N); \
+  td::bench(QueueBenchmark2<Q>(N));
+#define BENCH_Q(Q, N)                      \
+  std::fprintf(stderr, "%s %d:\t", #Q, N); \
+  td::bench(QueueBenchmark<Q>(N));
+
+#define BENCH_R(Q)                   \
+  std::fprintf(stderr, "%s:\t", #Q); \
+  td::bench(RingBenchmark<Q>());
+  // TODO: yield makes it extremely slow. Yet some backoff may be necessary.
+  //  BENCH_R(SemQueue);
+  //  BENCH_R(td::PollQueue<qvalue_t>);
+
+  BENCH_Q2(td::PollQueue<qvalue_t>, 1);
+  BENCH_Q2(td::MpscPollableQueue<qvalue_t>, 1);
+  BENCH_Q2(td::PollQueue<qvalue_t>, 100);
+  BENCH_Q2(td::MpscPollableQueue<qvalue_t>, 100);
+  BENCH_Q2(td::PollQueue<qvalue_t>, 10);
+  BENCH_Q2(td::MpscPollableQueue<qvalue_t>, 10);
+
+  BENCH_Q(VarQueue, 1);
+  // BENCH_Q(FdQueue, 1);
+  // BENCH_Q(BufferedFdQueue, 1);
+  BENCH_Q(PipeQueue, 1);
+  BENCH_Q(SemCheatQueue, 1);
+  BENCH_Q(SemQueue, 1);
+
+  // BENCH_Q2(td::PollQueue<qvalue_t>, 100);
+  // BENCH_Q2(td::PollQueue<qvalue_t>, 10);
+  // BENCH_Q2(td::PollQueue<qvalue_t>, 4);
+  // BENCH_Q2(td::InfBackoffQueue<qvalue_t>, 100);
+
+  // BENCH_Q2(td::InfBackoffQueue<qvalue_t>, 1);
+  // BENCH_Q(SemCheatQueue, 1);
+
+  // BENCH_Q(BufferedFdQueue, 100);
+  // BENCH_Q(BufferedFdQueue, 10);
+
+  // BENCH_Q(BufferQueue, 4);
+  // BENCH_Q(BufferQueue, 100);
+  // BENCH_Q(BufferQueue, 10);
+  // BENCH_Q(BufferQueue, 1);
+
+  return 0;
+}
diff --git a/libs/tdlib/td/benchmark/bench_tddb.cpp b/libs/tdlib/td/benchmark/bench_tddb.cpp
new file mode 100644
index 0000000000..91e957a501
--- /dev/null
+++ b/libs/tdlib/td/benchmark/bench_tddb.cpp
@@ -0,0 +1,108 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/DialogId.h"
+#include "td/telegram/MessageId.h"
+#include "td/telegram/MessagesDb.h"
+#include "td/telegram/UserId.h"
+
+#include "td/utils/benchmark.h"
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/Random.h"
+#include "td/utils/Status.h"
+
+#include <memory>
+
+namespace td {
+
+static Status init_db(SqliteDb &db) {
+  TRY_STATUS(db.exec("PRAGMA encoding=\"UTF-8\""));
+  TRY_STATUS(db.exec("PRAGMA synchronous=NORMAL"));
+  TRY_STATUS(db.exec("PRAGMA journal_mode=WAL"));
+  TRY_STATUS(db.exec("PRAGMA temp_store=MEMORY"));
+  TRY_STATUS(db.exec("PRAGMA secure_delete=1"));
+  return Status::OK();
+}
+
+class MessagesDbBench : public Benchmark {
+ public:
+  string get_description() const override {
+    return "MessagesDb";
+  }
+  void start_up() override {
+    LOG(ERROR) << "START UP";
+    do_start_up().ensure();
+    scheduler_->start();
+  }
+  void run(int n) override {
+    auto guard = scheduler_->get_current_guard();
+    for (int i = 0; i < n; i += 20) {
+      auto dialog_id = DialogId{UserId{Random::fast(1, 100)}};
+      auto message_id_raw = Random::fast(1, 100000);
+      for (int j = 0; j < 20; j++) {
+        auto message_id = MessageId{ServerMessageId{message_id_raw + j}};
+        auto unique_message_id = ServerMessageId{i + 1};
+        auto sender_user_id = UserId{Random::fast(1, 1000)};
+        auto random_id = i + 1;
+        auto ttl_expires_at = 0;
+        auto data = BufferSlice(Random::fast(100, 299));
+
+        // use async on same thread.
+        messages_db_async_->add_message({dialog_id, message_id}, unique_message_id, sender_user_id, random_id,
+                                        ttl_expires_at, 0, 0, "", std::move(data), Promise<>());
+      }
+    }
+  }
+  void tear_down() override {
+    scheduler_->run_main(0.1);
+    {
+      auto guard = scheduler_->get_current_guard();
+      sql_connection_.reset();
+      messages_db_sync_safe_.reset();
+      messages_db_async_.reset();
+    }
+
+    scheduler_->finish();
+    scheduler_.reset();
+    LOG(ERROR) << "TEAR DOWN";
+  }
+
+ private:
+  std::unique_ptr<td::ConcurrentScheduler> scheduler_;
+  std::shared_ptr<SqliteConnectionSafe> sql_connection_;
+  std::shared_ptr<MessagesDbSyncSafeInterface> messages_db_sync_safe_;
+  std::shared_ptr<MessagesDbAsyncInterface> messages_db_async_;
+
+  Status do_start_up() {
+    scheduler_ = std::make_unique<ConcurrentScheduler>();
+    scheduler_->init(1);
+
+    auto guard = scheduler_->get_current_guard();
+
+    string sql_db_name = "testdb.sqlite";
+    sql_connection_ = std::make_shared<SqliteConnectionSafe>(sql_db_name);
+    auto &db = sql_connection_->get();
+    TRY_STATUS(init_db(db));
+
+    db.exec("BEGIN TRANSACTION").ensure();
+    // version == 0 ==> db will be destroyed
+    TRY_STATUS(init_messages_db(db, 0));
+    db.exec("COMMIT TRANSACTION").ensure();
+
+    messages_db_sync_safe_ = create_messages_db_sync(sql_connection_);
+    messages_db_async_ = create_messages_db_async(messages_db_sync_safe_, 0);
+    return Status::OK();
+  }
+};
+}  // namespace td
+
+int main() {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(WARNING));
+  bench(td::MessagesDbBench());
+  return 0;
+}
diff --git a/libs/tdlib/td/benchmark/rmdir.cpp b/libs/tdlib/td/benchmark/rmdir.cpp
new file mode 100644
index 0000000000..f1676baa63
--- /dev/null
+++ b/libs/tdlib/td/benchmark/rmdir.cpp
@@ -0,0 +1,28 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/logging.h"
+#include "td/utils/port/path.h"
+#include "td/utils/Slice.h"
+
+int main(int argc, char *argv[]) {
+  if (argc < 1) {
+    return 1;
+  }
+  td::CSlice dir(argv[1]);
+  int cnt = 0;
+  auto status = td::walk_path(dir, [&](td::CSlice path, bool is_dir) {
+    cnt++;
+    LOG(INFO) << path << " " << is_dir;
+    // if (is_dir) {
+    // td::rmdir(path);
+    //} else {
+    // td::unlink(path);
+    //}
+  });
+  LOG(INFO) << status << ": " << cnt;
+  return 0;
+}
diff --git a/libs/tdlib/td/benchmark/wget.cpp b/libs/tdlib/td/benchmark/wget.cpp
new file mode 100644
index 0000000000..dba997e61f
--- /dev/null
+++ b/libs/tdlib/td/benchmark/wget.cpp
@@ -0,0 +1,39 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/net/HttpQuery.h"
+#include "td/net/Wget.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/Status.h"
+
+#include <memory>
+#include <string>
+
+int main(int argc, char *argv[]) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(INFO));
+  td::VERBOSITY_NAME(fd) = VERBOSITY_NAME(INFO);
+
+  std::string url = (argc > 1 ? argv[1] : "https://telegram.org");
+  auto scheduler = std::make_unique<td::ConcurrentScheduler>();
+  scheduler->init(0);
+  scheduler
+      ->create_actor_unsafe<td::Wget>(0, "Client", td::PromiseCreator::lambda([](td::Result<td::HttpQueryPtr> res) {
+                                        LOG(ERROR) << *res.ok();
+                                        td::Scheduler::instance()->finish();
+                                      }),
+                                      url)
+      .release();
+  scheduler->start();
+  while (scheduler->run_main(10)) {
+    // empty
+  }
+  scheduler->finish();
+  return 0;
+}
diff --git a/libs/tdlib/td/bitbucket-pipelines.yml b/libs/tdlib/td/bitbucket-pipelines.yml
new file mode 100644
index 0000000000..4dbdf6c914
--- /dev/null
+++ b/libs/tdlib/td/bitbucket-pipelines.yml
@@ -0,0 +1,16 @@
+image: gcc:5.4
+
+pipelines:
+  default:
+    - step:
+        script:
+          - apt-get update
+          - apt-get install -y cmake
+          - apt-get install -y gperf
+          - g++ --version
+          - cmake --version
+          - mkdir build
+          - cd build
+          - cmake ..
+          - make -k run_all_tests
+          - ./test/run_all_tests
diff --git a/libs/tdlib/td/example/cpp/.gitignore b/libs/tdlib/td/example/cpp/.gitignore
new file mode 100644
index 0000000000..336dc7d458
--- /dev/null
+++ b/libs/tdlib/td/example/cpp/.gitignore
@@ -0,0 +1 @@
+td/
diff --git a/libs/tdlib/td/example/cpp/CMakeLists.txt b/libs/tdlib/td/example/cpp/CMakeLists.txt
new file mode 100644
index 0000000000..3e7794d4fa
--- /dev/null
+++ b/libs/tdlib/td/example/cpp/CMakeLists.txt
@@ -0,0 +1,13 @@
+cmake_minimum_required(VERSION 3.1 FATAL_ERROR)
+
+project(TdExample VERSION 1.0 LANGUAGES CXX)
+
+find_package(Td 1.2.0 REQUIRED)
+
+add_executable(tdjson_example tdjson_example.cpp)
+target_link_libraries(tdjson_example PRIVATE Td::TdJson)
+set_property(TARGET tdjson_example PROPERTY CXX_STANDARD 11)
+
+add_executable(td_example td_example.cpp)
+target_link_libraries(td_example PRIVATE Td::TdStatic)
+set_property(TARGET td_example PROPERTY CXX_STANDARD 14)
diff --git a/libs/tdlib/td/example/cpp/README.md b/libs/tdlib/td/example/cpp/README.md
new file mode 100644
index 0000000000..9e5de531ba
--- /dev/null
+++ b/libs/tdlib/td/example/cpp/README.md
@@ -0,0 +1,24 @@
+# TDLib cpp basic usage examples
+
+TDLib should be prebuilt and installed to local subdirectory `td/`:
+```
+cd <path to TDLib sources>
+mkdir build
+cd build
+cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX:PATH=../example/cpp/td ..
+cmake --build . --target install
+```
+Also see [building](https://github.com/tdlib/td#building) for additional details on TDLib building.
+
+Then you can build the examples:
+```
+cd <path to TDLib sources>/example/cpp
+mkdir build
+cd build
+cmake -DCMAKE_BUILD_TYPE=Release -DTd_DIR=<full path to TDLib sources>/example/cpp/td/lib/cmake/Td ..
+cmake --build .
+```
+
+Documentation for all available classes and methods can be found at https://core.telegram.org/tdlib/docs.
+
+To run `tdjson_example` you may need to manually copy a `tdjson` shared library from `td/bin` to a directory containing built binaries.
diff --git a/libs/tdlib/td/example/cpp/td_example.cpp b/libs/tdlib/td/example/cpp/td_example.cpp
new file mode 100644
index 0000000000..1efbf465b9
--- /dev/null
+++ b/libs/tdlib/td/example/cpp/td_example.cpp
@@ -0,0 +1,308 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include <td/telegram/Client.h>
+#include <td/telegram/Log.h>
+#include <td/telegram/td_api.h>
+#include <td/telegram/td_api.hpp>
+
+#include <cstdint>
+#include <functional>
+#include <iostream>
+#include <limits>
+#include <map>
+#include <sstream>
+#include <string>
+#include <vector>
+
+// Simple single-threaded example of TDLib usage.
+// Real world programs should use separate thread for the user input.
+// Example includes user authentication, receiving updates, getting chat list and sending text messages.
+
+// overloaded
+namespace detail {
+template <class... Fs>
+struct overload;
+
+template <class F>
+struct overload<F> : public F {
+  explicit overload(F f) : F(f) {
+  }
+};
+template <class F, class... Fs>
+struct overload<F, Fs...>
+    : public overload<F>
+    , overload<Fs...> {
+  overload(F f, Fs... fs) : overload<F>(f), overload<Fs...>(fs...) {
+  }
+  using overload<F>::operator();
+  using overload<Fs...>::operator();
+};
+}  // namespace detail
+
+template <class... F>
+auto overloaded(F... f) {
+  return detail::overload<F...>(f...);
+}
+
+namespace td_api = td::td_api;
+
+class TdExample {
+ public:
+  TdExample() {
+    td::Log::set_verbosity_level(1);
+    client_ = std::make_unique<td::Client>();
+  }
+
+  void loop() {
+    while (true) {
+      if (need_restart_) {
+        restart();
+      } else if (!are_authorized_) {
+        process_response(client_->receive(10));
+      } else {
+        std::cerr << "Enter action [q] quit [u] check for updates and request results [c] show chats [m <id> <text>] "
+                     "send message [l] logout: "
+                  << std::endl;
+        std::string line;
+        std::getline(std::cin, line);
+        std::istringstream ss(line);
+        std::string action;
+        if (!(ss >> action)) {
+          continue;
+        }
+        if (action == "q") {
+          return;
+        }
+        if (action == "u") {
+          std::cerr << "Checking for updates..." << std::endl;
+          while (true) {
+            auto response = client_->receive(0);
+            if (response.object) {
+              process_response(std::move(response));
+            } else {
+              break;
+            }
+          }
+        } else if (action == "l") {
+          std::cerr << "Logging out..." << std::endl;
+          send_query(td_api::make_object<td_api::logOut>(), {});
+        } else if (action == "m") {
+          std::int64_t chat_id;
+          ss >> chat_id;
+          ss.get();
+          std::string text;
+          std::getline(ss, text);
+
+          std::cerr << "Sending message to chat " << chat_id << "..." << std::endl;
+          auto send_message = td_api::make_object<td_api::sendMessage>();
+          send_message->chat_id_ = chat_id;
+          auto message_content = td_api::make_object<td_api::inputMessageText>();
+          message_content->text_ = td_api::make_object<td_api::formattedText>();
+          message_content->text_->text_ = std::move(text);
+          send_message->input_message_content_ = std::move(message_content);
+
+          send_query(std::move(send_message), {});
+        } else if (action == "c") {
+          std::cerr << "Loading chat list..." << std::endl;
+          send_query(td_api::make_object<td_api::getChats>(std::numeric_limits<std::int64_t>::max(), 0, 20),
+                     [this](Object object) {
+                       if (object->get_id() == td_api::error::ID) {
+                         return;
+                       }
+                       auto chats = td::move_tl_object_as<td_api::chats>(object);
+                       for (auto chat_id : chats->chat_ids_) {
+                         std::cerr << "[id:" << chat_id << "] [title:" << chat_title_[chat_id] << "]" << std::endl;
+                       }
+                     });
+        }
+      }
+    }
+  }
+
+ private:
+  using Object = td_api::object_ptr<td_api::Object>;
+  std::unique_ptr<td::Client> client_;
+
+  td_api::object_ptr<td_api::AuthorizationState> authorization_state_;
+  bool are_authorized_{false};
+  bool need_restart_{false};
+  std::uint64_t current_query_id_{0};
+  std::uint64_t authentication_query_id_{0};
+
+  std::map<std::uint64_t, std::function<void(Object)>> handlers_;
+
+  std::map<std::int32_t, td_api::object_ptr<td_api::user>> users_;
+
+  std::map<std::int64_t, std::string> chat_title_;
+
+  void restart() {
+    client_.reset();
+    *this = TdExample();
+  }
+
+  void send_query(td_api::object_ptr<td_api::Function> f, std::function<void(Object)> handler) {
+    auto query_id = next_query_id();
+    if (handler) {
+      handlers_.emplace(query_id, std::move(handler));
+    }
+    client_->send({query_id, std::move(f)});
+  }
+
+  void process_response(td::Client::Response response) {
+    if (!response.object) {
+      return;
+    }
+    //std::cerr << response.id << " " << to_string(response.object) << std::endl;
+    if (response.id == 0) {
+      return process_update(std::move(response.object));
+    }
+    auto it = handlers_.find(response.id);
+    if (it != handlers_.end()) {
+      it->second(std::move(response.object));
+    }
+  }
+
+  std::string get_user_name(std::int32_t user_id) {
+    auto it = users_.find(user_id);
+    if (it == users_.end()) {
+      return "unknown user";
+    }
+    return it->second->first_name_ + " " + it->second->last_name_;
+  }
+
+  void process_update(td_api::object_ptr<td_api::Object> update) {
+    td_api::downcast_call(
+        *update, overloaded(
+                     [this](td_api::updateAuthorizationState &update_authorization_state) {
+                       authorization_state_ = std::move(update_authorization_state.authorization_state_);
+                       on_authorization_state_update();
+                     },
+                     [this](td_api::updateNewChat &update_new_chat) {
+                       chat_title_[update_new_chat.chat_->id_] = update_new_chat.chat_->title_;
+                     },
+                     [this](td_api::updateChatTitle &update_chat_title) {
+                       chat_title_[update_chat_title.chat_id_] = update_chat_title.title_;
+                     },
+                     [this](td_api::updateUser &update_user) {
+                       auto user_id = update_user.user_->id_;
+                       users_[user_id] = std::move(update_user.user_);
+                     },
+                     [this](td_api::updateNewMessage &update_new_message) {
+                       auto chat_id = update_new_message.message_->chat_id_;
+                       auto sender_user_name = get_user_name(update_new_message.message_->sender_user_id_);
+                       std::string text;
+                       if (update_new_message.message_->content_->get_id() == td_api::messageText::ID) {
+                         text = static_cast<td_api::messageText &>(*update_new_message.message_->content_).text_->text_;
+                       }
+                       std::cerr << "Got message: [chat_id:" << chat_id << "] [from:" << sender_user_name << "] ["
+                                 << text << "]" << std::endl;
+                     },
+                     [](auto &update) {}));
+  }
+
+  auto create_authentication_query_handler() {
+    return [this, id = authentication_query_id_](Object object) {
+      if (id == authentication_query_id_) {
+        check_authentication_error(std::move(object));
+      }
+    };
+  }
+
+  void on_authorization_state_update() {
+    authentication_query_id_++;
+    td_api::downcast_call(
+        *authorization_state_,
+        overloaded(
+            [this](td_api::authorizationStateReady &) {
+              are_authorized_ = true;
+              std::cerr << "Got authorization" << std::endl;
+            },
+            [this](td_api::authorizationStateLoggingOut &) {
+              are_authorized_ = false;
+              std::cerr << "Logging out" << std::endl;
+            },
+            [this](td_api::authorizationStateClosing &) { std::cerr << "Closing" << std::endl; },
+            [this](td_api::authorizationStateClosed &) {
+              are_authorized_ = false;
+              need_restart_ = true;
+              std::cerr << "Terminated" << std::endl;
+            },
+            [this](td_api::authorizationStateWaitCode &wait_code) {
+              std::string first_name;
+              std::string last_name;
+              if (!wait_code.is_registered_) {
+                std::cerr << "Enter your first name: ";
+                std::cin >> first_name;
+                std::cerr << "Enter your last name: ";
+                std::cin >> last_name;
+              }
+              std::cerr << "Enter authentication code: ";
+              std::string code;
+              std::cin >> code;
+              send_query(td_api::make_object<td_api::checkAuthenticationCode>(code, first_name, last_name),
+                         create_authentication_query_handler());
+            },
+            [this](td_api::authorizationStateWaitPassword &) {
+              std::cerr << "Enter authentication password: ";
+              std::string password;
+              std::cin >> password;
+              send_query(td_api::make_object<td_api::checkAuthenticationPassword>(password),
+                         create_authentication_query_handler());
+            },
+            [this](td_api::authorizationStateWaitPhoneNumber &) {
+              std::cerr << "Enter phone number: ";
+              std::string phone_number;
+              std::cin >> phone_number;
+              send_query(td_api::make_object<td_api::setAuthenticationPhoneNumber>(
+                             phone_number, false /*allow_flash_calls*/, false /*is_current_phone_number*/),
+                         create_authentication_query_handler());
+            },
+            [this](td_api::authorizationStateWaitEncryptionKey &) {
+              std::cerr << "Enter encryption key or DESTROY: ";
+              std::string key;
+              std::getline(std::cin, key);
+              if (key == "DESTROY") {
+                send_query(td_api::make_object<td_api::destroy>(), create_authentication_query_handler());
+              } else {
+                send_query(td_api::make_object<td_api::checkDatabaseEncryptionKey>(std::move(key)),
+                           create_authentication_query_handler());
+              }
+            },
+            [this](td_api::authorizationStateWaitTdlibParameters &) {
+              auto parameters = td_api::make_object<td_api::tdlibParameters>();
+              parameters->database_directory_ = "tdlib";
+              parameters->use_message_database_ = true;
+              parameters->use_secret_chats_ = true;
+              parameters->api_id_ = 94575;
+              parameters->api_hash_ = "a3406de8d171bb422bb6ddf3bbd800e2";
+              parameters->system_language_code_ = "en";
+              parameters->device_model_ = "Desktop";
+              parameters->system_version_ = "Unknown";
+              parameters->application_version_ = "1.0";
+              parameters->enable_storage_optimizer_ = true;
+              send_query(td_api::make_object<td_api::setTdlibParameters>(std::move(parameters)),
+                         create_authentication_query_handler());
+            }));
+  }
+
+  void check_authentication_error(Object object) {
+    if (object->get_id() == td_api::error::ID) {
+      auto error = td::move_tl_object_as<td_api::error>(object);
+      std::cerr << "Error: " << to_string(error);
+      on_authorization_state_update();
+    }
+  }
+
+  std::uint64_t next_query_id() {
+    return ++current_query_id_;
+  }
+};
+
+int main() {
+  TdExample example;
+  example.loop();
+}
diff --git a/libs/tdlib/td/example/cpp/tdjson_example.cpp b/libs/tdlib/td/example/cpp/tdjson_example.cpp
new file mode 100644
index 0000000000..6787b37f86
--- /dev/null
+++ b/libs/tdlib/td/example/cpp/tdjson_example.cpp
@@ -0,0 +1,33 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include <iostream>
+#include <td/telegram/td_json_client.h>
+
+// Basic example of TDLib JSON interface usage.
+// Native interface should be preferred instead in C++, so here is only an example of
+// the main event cycle, which should be essentially the same for all languages.
+
+int main() {
+  void *client = td_json_client_create();
+  // somehow share the client with other threads, which will be able to send requests via td_json_client_send
+
+  const double WAIT_TIMEOUT = 10.0;  // seconds
+  while (true) {
+    const char *result = td_json_client_receive(client, WAIT_TIMEOUT);
+    if (result != nullptr) {
+      // parse the result as JSON object and process it as an incoming update or an answer to a previously sent request
+
+      // if (result is UpdateAuthorizationState with authorizationStateClosed) {
+      //   break;
+      // }
+
+      std::cout << result << std::endl;
+    }
+  }
+
+  td_json_client_destroy(client);
+}
diff --git a/libs/tdlib/td/example/csharp/.gitignore b/libs/tdlib/td/example/csharp/.gitignore
new file mode 100644
index 0000000000..5266ecccc9
--- /dev/null
+++ b/libs/tdlib/td/example/csharp/.gitignore
@@ -0,0 +1,5 @@
+.vs/
+bin/
+obj/
+project.lock.json
+TdExample.csproj.user
diff --git a/libs/tdlib/td/example/csharp/README.md b/libs/tdlib/td/example/csharp/README.md
new file mode 100644
index 0000000000..2faa15e12e
--- /dev/null
+++ b/libs/tdlib/td/example/csharp/README.md
@@ -0,0 +1,32 @@
+# TDLib C# example
+
+This is an example of building TDLib with `C++/CLI` support and an example of TDLib usage from C#.
+
+## Building TDLib
+
+* Download and install Microsoft Visual Studio 2015 or later.
+* Download and install [CMake](https://cmake.org/download/).
+* Install [vcpkg](https://github.com/Microsoft/vcpkg#quick-start) or update it to the latest version using `vcpkg update` and following received instructions.
+* Install `zlib` and `openssl` for using `vcpkg`:
+```
+C:\src\vcpkg> .\vcpkg.exe install openssl:x64-windows openssl:x86-windows zlib:x64-windows zlib:x86-windows
+```
+* (Optional. For XML documentation generation.) Download [PHP](https://windows.php.net/download#php-7.2). Add the path to php.exe to the PATH environment variable.
+* Download and install [gperf](https://sourceforge.net/projects/gnuwin32/files/gperf/3.0.1/). Add the path to gperf.exe to the PATH environment variable.
+* Build `TDLib` with CMake enabling `.NET` support and specifying correct path to `vcpkg` toolchain file:
+```
+cd <path to TDLib sources>/example/csharp
+mkdir build
+cd build
+cmake -DTD_ENABLE_DOTNET=ON -DCMAKE_TOOLCHAIN_FILE=C:\src\vcpkg\scripts\buildsystems\vcpkg.cmake ../../..
+cmake --build . --config Release
+cmake --build . --config Debug
+```
+
+## Example of usage
+
+After `TDLib` is built you can open and run TdExample project.
+It contains a simple console C# application with implementation of authorization and message sending.
+Just open it with Visual Studio 2015 or 2017 and run.
+
+Also see TdExample.csproj for example of including TDLib in C# project with all native shared library dependencies.
diff --git a/libs/tdlib/td/example/csharp/TdExample.cs b/libs/tdlib/td/example/csharp/TdExample.cs
new file mode 100644
index 0000000000..be98e1a758
--- /dev/null
+++ b/libs/tdlib/td/example/csharp/TdExample.cs
@@ -0,0 +1,270 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+using Td = Telegram.Td;
+using TdApi = Telegram.Td.Api;
+
+using System;
+using System.Threading;
+
+namespace TdExample
+{
+    /// <summary>
+    /// Example class for TDLib usage from C#.
+    /// </summary>
+    class Example
+    {
+        private static Td.Client _client = null;
+        private readonly static Td.ClientResultHandler _defaultHandler = new DefaultHandler();
+
+        private static TdApi.AuthorizationState _authorizationState = null;
+        private static volatile bool _haveAuthorization = false;
+        private static volatile bool _quiting = false;
+
+        private static volatile AutoResetEvent _gotAuthorization = new AutoResetEvent(false);
+
+        private static readonly string _newLine = Environment.NewLine;
+        private static readonly string _commandsLine = "Enter command (gc <chatId> - GetChat, me - GetMe, sm <chatId> <message> - SendMessage, lo - LogOut, q - Quit): ";
+        private static volatile string _currentPrompt = null;
+
+        private static Td.Client CreateTdClient()
+        {
+            Td.Client result = Td.Client.Create(new UpdatesHandler());
+            new Thread(() =>
+            {
+                Thread.CurrentThread.IsBackground = true;
+                result.Run();
+            }).Start();
+            return result;
+        }
+
+        private static void Print(string str)
+        {
+            if (_currentPrompt != null)
+            {
+                Console.WriteLine();
+            }
+            Console.WriteLine(str);
+            if (_currentPrompt != null)
+            {
+                Console.Write(_currentPrompt);
+            }
+        }
+
+        private static string ReadLine(string str)
+        {
+            Console.Write(str);
+            _currentPrompt = str;
+            var result = Console.ReadLine();
+            _currentPrompt = null;
+            return result;
+        }
+
+        private static void OnAuthorizationStateUpdated(TdApi.AuthorizationState authorizationState)
+        {
+            if (authorizationState != null)
+            {
+                _authorizationState = authorizationState;
+            }
+            if (_authorizationState is TdApi.AuthorizationStateWaitTdlibParameters)
+            {
+                TdApi.TdlibParameters parameters = new TdApi.TdlibParameters();
+                parameters.DatabaseDirectory = "tdlib";
+                parameters.UseMessageDatabase = true;
+                parameters.UseSecretChats = true;
+                parameters.ApiId = 94575;
+                parameters.ApiHash = "a3406de8d171bb422bb6ddf3bbd800e2";
+                parameters.SystemLanguageCode = "en";
+                parameters.DeviceModel = "Desktop";
+                parameters.SystemVersion = "Unknown";
+                parameters.ApplicationVersion = "1.0";
+                parameters.EnableStorageOptimizer = true;
+
+                _client.Send(new TdApi.SetTdlibParameters(parameters), new AuthorizationRequestHandler());
+            }
+            else if (_authorizationState is TdApi.AuthorizationStateWaitEncryptionKey)
+            {
+                _client.Send(new TdApi.CheckDatabaseEncryptionKey(), new AuthorizationRequestHandler());
+            }
+            else if (_authorizationState is TdApi.AuthorizationStateWaitPhoneNumber)
+            {
+                string phoneNumber = ReadLine("Please enter phone number: ");
+                _client.Send(new TdApi.SetAuthenticationPhoneNumber(phoneNumber, false, false), new AuthorizationRequestHandler());
+            }
+            else if (_authorizationState is TdApi.AuthorizationStateWaitCode)
+            {
+                string code = ReadLine("Please enter authentication code: ");
+                _client.Send(new TdApi.CheckAuthenticationCode(code, "", ""), new AuthorizationRequestHandler());
+            }
+            else if (_authorizationState is TdApi.AuthorizationStateWaitPassword)
+            {
+                string password = ReadLine("Please enter password: ");
+                _client.Send(new TdApi.CheckAuthenticationPassword(password), new AuthorizationRequestHandler());
+            }
+            else if (_authorizationState is TdApi.AuthorizationStateReady)
+            {
+                _haveAuthorization = true;
+                _gotAuthorization.Set();
+            }
+            else if (_authorizationState is TdApi.AuthorizationStateLoggingOut)
+            {
+                _haveAuthorization = false;
+                Print("Logging out");
+            }
+            else if (_authorizationState is TdApi.AuthorizationStateClosing)
+            {
+                _haveAuthorization = false;
+                Print("Closing");
+            }
+            else if (_authorizationState is TdApi.AuthorizationStateClosed)
+            {
+                Print("Closed");
+                if (!_quiting)
+                {
+                    _client = CreateTdClient(); // recreate _client after previous has closed
+                }
+            }
+            else
+            {
+                Print("Unsupported authorization state:" + _newLine + _authorizationState);
+            }
+        }
+
+        private static long GetChatId(string arg)
+        {
+            long chatId = 0;
+            try
+            {
+                chatId = Convert.ToInt64(arg);
+            }
+            catch (FormatException)
+            {
+            }
+            catch (OverflowException)
+            {
+            }
+            return chatId;
+        }
+
+        private static void GetCommand()
+        {
+            string command = ReadLine(_commandsLine);
+            string[] commands = command.Split(new char[] { ' ' }, 2);
+            try
+            {
+                switch (commands[0])
+                {
+                    case "gc":
+                        _client.Send(new TdApi.GetChat(GetChatId(commands[1])), _defaultHandler);
+                        break;
+                    case "me":
+                        _client.Send(new TdApi.GetMe(), _defaultHandler);
+                        break;
+                    case "sm":
+                        string[] args = commands[1].Split(new char[] { ' ' }, 2);
+                        sendMessage(GetChatId(args[0]), args[1]);
+                        break;
+                    case "lo":
+                        _haveAuthorization = false;
+                        _client.Send(new TdApi.LogOut(), _defaultHandler);
+                        break;
+                    case "q":
+                        _quiting = true;
+                        _haveAuthorization = false;
+                        _client.Send(new TdApi.Close(), _defaultHandler);
+                        break;
+                    default:
+                        Print("Unsupported command: " + command);
+                        break;
+                }
+            }
+            catch (IndexOutOfRangeException)
+            {
+                Print("Not enough arguments");
+            }
+        }
+
+        private static void sendMessage(long chatId, string message)
+        {
+            // initialize reply markup just for testing
+            TdApi.InlineKeyboardButton[] row = { new TdApi.InlineKeyboardButton("https://telegram.org?1", new TdApi.InlineKeyboardButtonTypeUrl()), new TdApi.InlineKeyboardButton("https://telegram.org?2", new TdApi.InlineKeyboardButtonTypeUrl()), new TdApi.InlineKeyboardButton("https://telegram.org?3", new TdApi.InlineKeyboardButtonTypeUrl()) };
+            TdApi.ReplyMarkup replyMarkup = new TdApi.ReplyMarkupInlineKeyboard(new TdApi.InlineKeyboardButton[][] { row, row, row });
+
+            TdApi.InputMessageContent content = new TdApi.InputMessageText(new TdApi.FormattedText(message, null), false, true);
+            _client.Send(new TdApi.SendMessage(chatId, 0, false, false, replyMarkup, content), _defaultHandler);
+        }
+
+        static void Main()
+        {
+            // disable TDLib log
+            Td.Log.SetVerbosityLevel(0);
+            if (!Td.Log.SetFilePath("tdlib.log"))
+            {
+                throw new System.IO.IOException("Write access to the current directory is required");
+            }
+
+            // create Td.Client
+            _client = CreateTdClient();
+
+            // test Client.Execute
+            _defaultHandler.OnResult(_client.Execute(new TdApi.GetTextEntities("@telegram /test_command https://telegram.org telegram.me @gif @test")));
+
+            // main loop
+            while (!_quiting)
+            {
+                // await authorization
+                _gotAuthorization.Reset();
+                _gotAuthorization.WaitOne();
+
+                _client.Send(new TdApi.GetChats(Int64.MaxValue, 0, 100), _defaultHandler); // preload chat list
+                while (_haveAuthorization)
+                {
+                    GetCommand();
+                }
+            }
+        }
+
+        private class DefaultHandler : Td.ClientResultHandler
+        {
+            void Td.ClientResultHandler.OnResult(TdApi.BaseObject @object)
+            {
+                Print(@object.ToString());
+            }
+        }
+
+        private class UpdatesHandler : Td.ClientResultHandler
+        {
+            void Td.ClientResultHandler.OnResult(TdApi.BaseObject @object)
+            {
+                if (@object is TdApi.UpdateAuthorizationState)
+                {
+                    OnAuthorizationStateUpdated((@object as TdApi.UpdateAuthorizationState).AuthorizationState);
+                }
+                else
+                {
+                    // Print("Unsupported update: " + @object);
+                }
+            }
+        }
+
+        private class AuthorizationRequestHandler : Td.ClientResultHandler
+        {
+            void Td.ClientResultHandler.OnResult(TdApi.BaseObject @object)
+            {
+                if (@object is TdApi.Error)
+                {
+                    Print("Receive an error:" + _newLine + @object);
+                    OnAuthorizationStateUpdated(null); // repeat last action
+                }
+                else
+                {
+                    // result is already received through UpdateAuthorizationState, nothing to do
+                }
+            }
+        }
+    }
+}
diff --git a/libs/tdlib/td/example/csharp/TdExample.csproj b/libs/tdlib/td/example/csharp/TdExample.csproj
new file mode 100644
index 0000000000..ea2ad56532
--- /dev/null
+++ b/libs/tdlib/td/example/csharp/TdExample.csproj
@@ -0,0 +1,85 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">x86</Platform>
+    <ProjectGuid>{3F9A93EA-DC26-4F8B-ACE0-131B33B00CA7}</ProjectGuid>
+    <OutputType>Exe</OutputType>
+    <NoStandardLibraries>false</NoStandardLibraries>
+    <AssemblyName>ConsoleApplication</AssemblyName>
+    <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
+    <TargetFrameworkProfile>Client</TargetFrameworkProfile>
+    <FileAlignment>512</FileAlignment>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|x86' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+    <PlatformTarget>x86</PlatformTarget>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|x86' ">
+    <DebugType>pdbonly</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+    <PlatformTarget>x86</PlatformTarget>
+  </PropertyGroup>
+  <PropertyGroup>
+    <RootNamespace>TdExample</RootNamespace>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="Microsoft.CSharp" />
+    <Reference Include="System" />
+    <Reference Include="System.Core" />
+    <Reference Include="System.Data" />
+    <Reference Include="System.Data.DataSetExtensions" />
+    <Reference Include="System.Xml" />
+    <Reference Include="System.Xml.Linq" />
+    <Reference Include="Telegram.Td, Version=0.0.0.0, Culture=neutral, processorArchitecture=AMD64">
+      <SpecificVersion>False</SpecificVersion>
+      <HintPath Condition=" '$(Configuration)' == 'Debug' ">build\Debug\Telegram.Td.dll</HintPath>
+      <HintPath Condition=" '$(Configuration)' == 'Release' ">build\Release\Telegram.Td.dll</HintPath>
+    </Reference>
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="TdExample.cs" />
+  </ItemGroup>
+  <ItemGroup Condition=" '$(Configuration)' == 'Debug' ">
+    <Content Include="build\Debug\LIBEAY32.dll">
+      <Link>LIBEAY32.dll</Link>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <Content Include="build\Debug\SSLEAY32.dll">
+      <Link>SSLEAY32.dll</Link>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <Content Include="build\Debug\zlibd1.dll">
+      <Link>zlibd1.dll</Link>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+  </ItemGroup>
+  <ItemGroup Condition=" '$(Configuration)' == 'Release' ">
+    <Content Include="build\Release\LIBEAY32.dll">
+      <Link>LIBEAY32.dll</Link>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <Content Include="build\Release\SSLEAY32.dll">
+      <Link>SSLEAY32.dll</Link>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <Content Include="build\Release\zlib1.dll">
+      <Link>zlib1.dll</Link>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+  </ItemGroup>
+  <Import Project="$(MSBuildToolsPath)\Microsoft.CSHARP.Targets" />
+  <ProjectExtensions>
+    <VisualStudio AllowExistingFolder="true" />
+  </ProjectExtensions>
+</Project>
\ No newline at end of file
diff --git a/libs/tdlib/td/example/go/main.go b/libs/tdlib/td/example/go/main.go
new file mode 100644
index 0000000000..430e067019
--- /dev/null
+++ b/libs/tdlib/td/example/go/main.go
@@ -0,0 +1,26 @@
+package main
+
+// #cgo LDFLAGS: -ltdjson
+// #include <td/telegram/td_json_client.h>
+import "C"
+import (
+	"log"
+	"unsafe"
+)
+
+func td_send(client unsafe.Pointer, query *C.char) {
+	C.td_json_client_send(client, query)
+}
+
+func td_receive(client unsafe.Pointer) string {
+	return C.GoString(C.td_json_client_receive(client, 1.0))
+}
+
+func main() {
+	var client unsafe.Pointer
+	client = C.td_json_client_create()
+
+	query := C.CString(`{"@type": "getAuthorizationState"}`)
+	td_send(client, query)
+	log.Println(td_receive(client))
+}
diff --git a/libs/tdlib/td/example/ios/README.md b/libs/tdlib/td/example/ios/README.md
new file mode 100644
index 0000000000..25a1e68fcc
--- /dev/null
+++ b/libs/tdlib/td/example/ios/README.md
@@ -0,0 +1,41 @@
+# Build for iOS
+
+Below are instructions for building TDLib for iOS, watchOS, tvOS, and also macOS.
+
+If you need only a macOS build, take a look at our build instructions for [macOS](https://github.com/tdlib/td#macos).
+
+For example of usage take a look at our [Swift example](https://github.com/tdlib/td/tree/master/example/swift).
+
+To compile `TDLib` you will need to:
+* Install the latest Xcode command line tools.
+* Install other build dependencies, for example, using [Homebrew](https://brew.sh):
+```
+brew install gperf cmake
+```
+* If you don't want to build `TDLib` for macOS, you can pregenerate required source code files using CMake prepare_cross_compiling target:
+```
+cd <path to TDLib sources>
+mkdir native-build
+cd native-build
+cmake ..
+cmake --build . --target prepare_cross_compiling
+```
+* Build OpenSSL for iOS, watchOS, tvOS and macOS:
+```
+cd <path to TDLib sources>/example/ios
+./build-openssl.sh
+```
+Here we use scripts from [Python Apple support](https://github.com/pybee/Python-Apple-support), but any other OpenSSL builds should work too.
+Built libraries should be stored in `third_party/openssl/<platform>`, because the next script will rely on this location.
+* Build TDLib for iOS, watchOS, tvOS and macOS:
+```
+cd <path to TDLib sources>/example/ios
+./build.sh
+```
+This may take a while, because TDLib will be built about 10 times.
+Resulting library for iOS will work on any architecture (arv7, armv7s, arm64) and even on a simulator.
+We use [CMake/iOS.cmake](https://github.com/tdlib/td/blob/master/CMake/iOS.cmake) toolchain, other toolchains may work too.
+
+Built libraries will be store in `tdjson` directory.
+
+Documentation for all available classes and methods can be found at https://core.telegram.org/tdlib/docs.
diff --git a/libs/tdlib/td/example/ios/build-openssl.sh b/libs/tdlib/td/example/ios/build-openssl.sh
new file mode 100644
index 0000000000..2ad9dbcfee
--- /dev/null
+++ b/libs/tdlib/td/example/ios/build-openssl.sh
@@ -0,0 +1,22 @@
+#!/bin/sh
+
+git clone https://github.com/pybee/Python-Apple-support
+cd Python-Apple-support
+git checkout 2.7
+cd ..
+
+#TODO: change openssl version
+platforms="macOS iOS watchOS tvOS"
+for platform in $platforms;
+do
+  echo $platform
+  cd Python-Apple-support
+  #NB: -j will fail
+  make OpenSSL-$platform
+  cd ..
+  rm -rf third_party/openssl/$platform
+  mkdir -p third_party/openssl/$platform/lib
+  cp ./Python-Apple-support/build/$platform/libcrypto.a third_party/openssl/$platform/lib/
+  cp ./Python-Apple-support/build/$platform/libssl.a third_party/openssl/$platform/lib/
+  cp -r ./Python-Apple-support/build/$platform/Support/OpenSSL/Headers/ third_party/openssl/$platform/include
+done
diff --git a/libs/tdlib/td/example/ios/build.sh b/libs/tdlib/td/example/ios/build.sh
new file mode 100644
index 0000000000..9970008a1c
--- /dev/null
+++ b/libs/tdlib/td/example/ios/build.sh
@@ -0,0 +1,74 @@
+#/bin/sh
+td_path=$(realpath ../..)
+
+rm -rf build
+mkdir -p build
+cd build
+
+platforms="macOS iOS watchOS tvOS"
+for platform in $platforms;
+do
+  echo "Platform = ${platform} Simulator = ${simulator}"
+  openssl_path=$(realpath ../third_party/openssl/${platform})
+  echo "OpenSSL path = ${openssl_path}"
+  openssl_crypto_library="${openssl_path}/lib/libcrypto.a"
+  openssl_ssl_library="${openssl_path}/lib/libssl.a"
+  options="$options -DOPENSSL_FOUND=1"
+  options="$options -DOPENSSL_CRYPTO_LIBRARY=${openssl_crypto_library}"
+  #options="$options -DOPENSSL_SSL_LIBRARY=${openssl_ssl_library}"
+  options="$options -DOPENSSL_INCLUDE_DIR=${openssl_path}/include"
+  options="$options -DOPENSSL_LIBRARIES=${openssl_crypto_library};${openssl_ssl_library}"
+  options="$options -DCMAKE_BUILD_TYPE=Release"
+  if [[ $platform = "macOS" ]]; then
+    build="build-${platform}"
+    install="install-${platform}"
+    rm -rf $build
+    mkdir -p $build
+    mkdir -p $install
+    cd $build
+    cmake $td_path $options -DCMAKE_INSTALL_PREFIX=../${install}
+    make -j3 install || exit
+    cd ..
+    mkdir -p $platform
+    cp $build/libtdjson.dylib $platform/libtdjson.dylib
+    install_name_tool -id @rpath/libtdjson.dylib $platform/libtdjson.dylib
+  else
+    simulators="0 1"
+    for simulator in $simulators;
+    do
+      build="build-${platform}"
+      install="install-${platform}"
+      if [[ $simulator = "1" ]]; then
+        build="${build}-simulator"
+        install="${install}-simulator"
+        ios_platform="SIMULATOR"
+      else
+        ios_platform="OS"
+      fi
+      if [[ $platform = "watchOS" ]]; then
+        ios_platform="WATCH${ios_platform}"
+      fi
+      if [[ $platform = "tvOS" ]]; then
+        ios_platform="TV${ios_platform}"
+      fi
+      echo $ios_platform
+      rm -rf $build
+      mkdir -p $build
+      mkdir -p $install
+      cd $build
+      cmake $td_path $options -DIOS_PLATFORM=${ios_platform} -DCMAKE_TOOLCHAIN_FILE=${td_path}/CMake/iOS.cmake -DCMAKE_INSTALL_PREFIX=../${install}
+      make -j3 install || exit
+      cd ..
+    done
+    lib="install-${platform}/lib/libtdjson.dylib"
+    lib_simulator="install-${platform}-simulator/lib/libtdjson.dylib"
+    mkdir -p $platform
+    lipo -create $lib $lib_simulator -o $platform/libtdjson.dylib
+    install_name_tool -id @rpath/libtdjson.dylib $platform/libtdjson.dylib
+  fi
+
+  mkdir -p ../tdjson/$platform/include
+  rsync --recursive ${install}/include/ ../tdjson/${platform}/include/
+  mkdir -p ../tdjson/$platform/lib
+  cp $platform/libtdjson.dylib ../tdjson/$platform/lib/
+done
diff --git a/libs/tdlib/td/example/java/.gitignore b/libs/tdlib/td/example/java/.gitignore
new file mode 100644
index 0000000000..8f846b80d9
--- /dev/null
+++ b/libs/tdlib/td/example/java/.gitignore
@@ -0,0 +1,5 @@
+**/*build/
+bin/
+docs/
+org/drinkless/tdlib/TdApi.java
+td/
diff --git a/libs/tdlib/td/example/java/CMakeLists.txt b/libs/tdlib/td/example/java/CMakeLists.txt
new file mode 100644
index 0000000000..e8313a68b7
--- /dev/null
+++ b/libs/tdlib/td/example/java/CMakeLists.txt
@@ -0,0 +1,68 @@
+cmake_minimum_required(VERSION 3.1 FATAL_ERROR)
+
+project(TdJavaExample VERSION 1.0 LANGUAGES CXX)
+
+find_package(Td REQUIRED)
+
+if (NOT JNI_FOUND)
+  find_package(JNI REQUIRED)
+endif()
+message(STATUS "Found JNI: ${JNI_INCLUDE_DIRS} ${JNI_LIBRARIES}")
+
+if (NOT Java_FOUND)
+  find_package(Java 1.6 REQUIRED)
+endif()
+message(STATUS "Found Java: ${Java_JAVAC_EXECUTABLE} ${Java_JAVADOC_EXECUTABLE}")
+
+# Generating TdApi.java
+find_program(PHP_EXECUTABLE php)
+
+set(TD_API_JAVA_PACKAGE "org/drinkless/tdlib")
+set(TD_API_JAVA_PATH ${CMAKE_CURRENT_SOURCE_DIR})
+set(TD_API_TLO_PATH ${CMAKE_CURRENT_SOURCE_DIR}/td/bin/td/generate/scheme/td_api.tlo)
+set(TD_API_TL_PATH ${CMAKE_CURRENT_SOURCE_DIR}/td/bin/td/generate/scheme/td_api.tl)
+set(JAVADOC_TL_DOCUMENTATION_GENERATOR_PATH ${CMAKE_CURRENT_SOURCE_DIR}/td/bin/td/generate/JavadocTlDocumentationGenerator.php)
+set(GENERATE_JAVA_API_CMD ${CMAKE_CURRENT_SOURCE_DIR}/td/bin/td_generate_java_api TdApi ${TD_API_TLO_PATH} ${TD_API_JAVA_PATH} ${TD_API_JAVA_PACKAGE})
+if (PHP_EXECUTABLE)
+  set(GENERATE_JAVA_API_CMD ${GENERATE_JAVA_API_CMD} && ${PHP_EXECUTABLE} ${JAVADOC_TL_DOCUMENTATION_GENERATOR_PATH} ${TD_API_TL_PATH} ${TD_API_JAVA_PATH}/${TD_API_JAVA_PACKAGE}/TdApi.java)
+endif()
+
+add_custom_target(td_generate_java_api
+  COMMAND ${GENERATE_JAVA_API_CMD}
+  COMMENT "Generating Java TDLib API source files"
+  DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/td/bin/td_generate_java_api ${TD_API_TLO_PATH} ${TD_API_TL_PATH} ${JAVADOC_TL_DOCUMENTATION_GENERATOR_PATH}
+)
+
+set(JAVA_SOURCE_PATH "${TD_API_JAVA_PATH}/${TD_API_JAVA_PACKAGE}")
+get_filename_component(JAVA_OUTPUT_DIRECTORY ${CMAKE_INSTALL_PREFIX}/bin REALPATH BASE_DIR "${CMAKE_CURRENT_BINARY_DIR}")
+file(MAKE_DIRECTORY ${JAVA_OUTPUT_DIRECTORY})
+add_custom_target(build_java
+  COMMAND ${Java_JAVAC_EXECUTABLE} -d ${JAVA_OUTPUT_DIRECTORY} ${JAVA_SOURCE_PATH}/example/Example.java ${JAVA_SOURCE_PATH}/Client.java ${JAVA_SOURCE_PATH}/Log.java ${JAVA_SOURCE_PATH}/TdApi.java
+  COMMENT "Building Java code"
+  DEPENDS td_generate_java_api
+)
+
+set(JAVA_SOURCE_PATH "${TD_API_JAVA_PATH}/${TD_API_JAVA_PACKAGE}")
+add_custom_target(generate_javadoc
+  COMMAND ${Java_JAVADOC_EXECUTABLE} -d ${JAVA_OUTPUT_DIRECTORY}/../docs org.drinkless.tdlib
+  WORKING_DIRECTORY ${TD_API_JAVA_PATH}
+  COMMENT "Generating Javadoc documentation"
+  DEPENDS td_generate_java_api
+)
+
+# Building shared library
+add_library(tdjni SHARED
+  td_jni.cpp
+)
+target_include_directories(tdjni PRIVATE ${JAVA_INCLUDE_PATH} ${JAVA_INCLUDE_PATH2})
+target_link_libraries(tdjni PRIVATE Td::TdStatic ${JAVA_JVM_LIBRARY})
+target_compile_definitions(tdjni PRIVATE PACKAGE_NAME="${TD_API_JAVA_PACKAGE}")
+
+set_property(TARGET tdjni PROPERTY CXX_STANDARD 14)
+
+add_dependencies(tdjni td_generate_java_api build_java generate_javadoc)
+
+install(TARGETS tdjni
+  LIBRARY DESTINATION bin
+  RUNTIME DESTINATION bin
+)
diff --git a/libs/tdlib/td/example/java/README.md b/libs/tdlib/td/example/java/README.md
new file mode 100644
index 0000000000..c2b5c43171
--- /dev/null
+++ b/libs/tdlib/td/example/java/README.md
@@ -0,0 +1,39 @@
+# TDLib Java example
+
+To run this example, you will need installed JDK >= 1.6.
+For Javadoc documentation generation PHP is needed.
+
+TDLib should be prebuilt for using with Java and installed to local subdirectory `td/` as follows:
+```
+cd <path to TDLib sources>
+mkdir jnibuild
+cd jnibuild
+cmake -DCMAKE_BUILD_TYPE=Release -DTD_ENABLE_JNI=ON -DCMAKE_INSTALL_PREFIX:PATH=../example/java/td ..
+cmake --build . --target install
+```
+If you want to compile TDLib for 64-bit Java on Windows using MSVC, you will also need to add `-A x64` option to CMake.
+
+In Windows, use Vcpkg toolchain file by adding parameter -DCMAKE_TOOLCHAIN_FILE=<VCPKG_DIR>/scripts/buildsystems/vcpkg.cmake
+
+Then you can build this example:
+```
+cd <path to TDLib sources>/example/java
+mkdir build
+cd build
+cmake -DCMAKE_BUILD_TYPE=Release -DTd_DIR=<full path to TDLib sources>/example/java/td/lib/cmake/Td -DCMAKE_INSTALL_PREFIX:PATH=.. ..
+cmake --build . --target install
+```
+
+Compiled TDLib shared library and Java example after that will be placed in bin/ and Javadoc documentation in `docs/`.
+
+Now you can run Java example:
+```
+cd <path to TDLib sources>/example/java/bin
+java '-Djava.library.path=.' org/drinkless/tdlib/example/Example
+```
+
+If you get "Could NOT find JNI ..." error from CMake, you need to specify to CMake path to the installed JDK, for example, "-DJAVA_HOME=/usr/lib/jvm/java-8-oracle/".
+
+If you get java.lang.UnsatisfiedLinkError with "Can't find dependent libraries", you may also need to copy some dependent shared libraries to `bin/`.
+
+In case you compiled the example as 32-bit version, you may need to give -d32 parameter to Java.
diff --git a/libs/tdlib/td/example/java/org/drinkless/tdlib/Client.java b/libs/tdlib/td/example/java/org/drinkless/tdlib/Client.java
new file mode 100644
index 0000000000..efb38e9c5a
--- /dev/null
+++ b/libs/tdlib/td/example/java/org/drinkless/tdlib/Client.java
@@ -0,0 +1,285 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+package org.drinkless.tdlib;
+
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
+/**
+ * Main class for interaction with the TDLib.
+ */
+public final class Client implements Runnable {
+    /**
+     * Interface for handler for results of queries to TDLib and incoming updates from TDLib.
+     */
+    public interface ResultHandler {
+        /**
+         * Callback called on result of query to TDLib or incoming update from TDLib.
+         *
+         * @param object Result of query or update of type TdApi.Update about new events.
+         */
+        void onResult(TdApi.Object object);
+    }
+
+    /**
+     * Interface for handler of exceptions thrown while invoking ResultHandler.
+     * By default, all such exceptions are ignored.
+     * All exceptions thrown from ExceptionHandler are ignored.
+     */
+    public interface ExceptionHandler {
+        /**
+         * Callback called on exceptions thrown while invoking ResultHandler.
+         *
+         * @param e Exception thrown by ResultHandler.
+         */
+        void onException(Throwable e);
+    }
+
+    /**
+     * Sends a request to the TDLib.
+     *
+     * @param query            Object representing a query to the TDLib.
+     * @param resultHandler    Result handler with onResult method which will be called with result
+     *                         of the query or with TdApi.Error as parameter. If it is null, nothing
+     *                         will be called.
+     * @param exceptionHandler Exception handler with onException method which will be called on
+     *                         exception thrown from resultHandler. If it is null, then
+     *                         defaultExceptionHandler will be called.
+     * @throws NullPointerException if query is null.
+     */
+    public void send(TdApi.Function query, ResultHandler resultHandler, ExceptionHandler exceptionHandler) {
+        if (query == null) {
+            throw new NullPointerException("query is null");
+        }
+
+        readLock.lock();
+        try {
+            if (isClientDestroyed) {
+                if (resultHandler != null) {
+                    handleResult(new TdApi.Error(500, "Client is closed"), resultHandler, exceptionHandler);
+                }
+                return;
+            }
+
+            long queryId = currentQueryId.incrementAndGet();
+            handlers.put(queryId, new Handler(resultHandler, exceptionHandler));
+            nativeClientSend(nativeClientId, queryId, query);
+        } finally {
+            readLock.unlock();
+        }
+    }
+
+    /**
+     * Sends a request to the TDLib with an empty ExceptionHandler.
+     *
+     * @param query         Object representing a query to the TDLib.
+     * @param resultHandler Result handler with onResult method which will be called with result
+     *                      of the query or with TdApi.Error as parameter. If it is null, then
+     *                      defaultExceptionHandler will be called.
+     * @throws NullPointerException if query is null.
+     */
+    public void send(TdApi.Function query, ResultHandler resultHandler) {
+        send(query, resultHandler, null);
+    }
+
+    /**
+     * Synchronously executes a TDLib request. Only a few marked accordingly requests can be executed synchronously.
+     *
+     * @param query Object representing a query to the TDLib.
+     * @return request result.
+     * @throws NullPointerException if query is null.
+     */
+    public static TdApi.Object execute(TdApi.Function query) {
+        if (query == null) {
+            throw new NullPointerException("query is null");
+        }
+        return nativeClientExecute(query);
+    }
+
+    /**
+     * Replaces handler for incoming updates from the TDLib.
+     *
+     * @param updatesHandler   Handler with onResult method which will be called for every incoming
+     *                         update from the TDLib.
+     * @param exceptionHandler Exception handler with onException method which will be called on
+     *                         exception thrown from updatesHandler, if it is null, defaultExceptionHandler will be invoked.
+     */
+    public void setUpdatesHandler(ResultHandler updatesHandler, ExceptionHandler exceptionHandler) {
+        handlers.put(0L, new Handler(updatesHandler, exceptionHandler));
+    }
+
+    /**
+     * Replaces handler for incoming updates from the TDLib. Sets empty ExceptionHandler.
+     *
+     * @param updatesHandler Handler with onResult method which will be called for every incoming
+     *                       update from the TDLib.
+     */
+    public void setUpdatesHandler(ResultHandler updatesHandler) {
+        setUpdatesHandler(updatesHandler, null);
+    }
+
+    /**
+     * Replaces default exception handler to be invoked on exceptions thrown from updatesHandler and all other ResultHandler.
+     *
+     * @param defaultExceptionHandler Default exception handler. If null Exceptions are ignored.
+     */
+    public void setDefaultExceptionHandler(Client.ExceptionHandler defaultExceptionHandler) {
+        this.defaultExceptionHandler = defaultExceptionHandler;
+    }
+
+    /**
+     * Overridden method from Runnable, do not call it directly.
+     */
+    @Override
+    public void run() {
+        while (!stopFlag) {
+            receiveQueries(300.0 /*seconds*/);
+        }
+    }
+
+    /**
+     * Creates new Client.
+     *
+     * @param updatesHandler          Handler for incoming updates.
+     * @param updatesExceptionHandler Handler for exceptions thrown from updatesHandler. If it is null, exceptions will be iggnored.
+     * @param defaultExceptionHandler Default handler for exceptions thrown from all ResultHandler. If it is null, exceptions will be iggnored.
+     * @return created Client
+     */
+    public static Client create(ResultHandler updatesHandler, ExceptionHandler updatesExceptionHandler, ExceptionHandler defaultExceptionHandler) {
+        Client client = new Client(updatesHandler, updatesExceptionHandler, defaultExceptionHandler);
+        new Thread(client, "TDLib thread").start();
+        return client;
+    }
+
+    /**
+     * Closes Client.
+     */
+    public void close() {
+        writeLock.lock();
+        try {
+            if (isClientDestroyed) {
+                return;
+            }
+            if (!stopFlag) {
+                send(new TdApi.Close(), null);
+            }
+            isClientDestroyed = true;
+            while (!stopFlag) {
+                Thread.yield();
+            }
+            while (handlers.size() != 1) {
+                receiveQueries(300.0);
+            }
+            destroyNativeClient(nativeClientId);
+        } finally {
+            writeLock.unlock();
+        }
+    }
+
+    private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock();
+    private final Lock readLock = readWriteLock.readLock();
+    private final Lock writeLock = readWriteLock.writeLock();
+
+    private volatile boolean stopFlag = false;
+    private volatile boolean isClientDestroyed = false;
+    private final long nativeClientId;
+
+    private final ConcurrentHashMap<Long, Handler> handlers = new ConcurrentHashMap<Long, Handler>();
+    private final AtomicLong currentQueryId = new AtomicLong();
+
+    private volatile ExceptionHandler defaultExceptionHandler = null;
+
+    private static final int MAX_EVENTS = 1000;
+    private final long[] eventIds = new long[MAX_EVENTS];
+    private final TdApi.Object[] events = new TdApi.Object[MAX_EVENTS];
+
+    private static class Handler {
+        final ResultHandler resultHandler;
+        final ExceptionHandler exceptionHandler;
+
+        Handler(ResultHandler resultHandler, ExceptionHandler exceptionHandler) {
+            this.resultHandler = resultHandler;
+            this.exceptionHandler = exceptionHandler;
+        }
+    }
+
+    private Client(ResultHandler updatesHandler, ExceptionHandler updateExceptionHandler, ExceptionHandler defaultExceptionHandler) {
+        nativeClientId = createNativeClient();
+        handlers.put(0L, new Handler(updatesHandler, updateExceptionHandler));
+        this.defaultExceptionHandler = defaultExceptionHandler;
+    }
+
+    @Override
+    protected void finalize() throws Throwable {
+        try {
+            close();
+        } finally {
+            super.finalize();
+        }
+    }
+
+    private void processResult(long id, TdApi.Object object) {
+        if (object instanceof TdApi.UpdateAuthorizationState) {
+            if (((TdApi.UpdateAuthorizationState) object).authorizationState instanceof TdApi.AuthorizationStateClosed) {
+                stopFlag = true;
+            }
+        }
+        Handler handler;
+        if (id == 0) {
+            // update handler stays forever
+            handler = handlers.get(id);
+        } else {
+            handler = handlers.remove(id);
+        }
+        if (handler == null) {
+            return;
+        }
+
+        handleResult(object, handler.resultHandler, handler.exceptionHandler);
+    }
+
+    private void handleResult(TdApi.Object object, ResultHandler resultHandler, ExceptionHandler exceptionHandler) {
+        if (resultHandler == null) {
+            return;
+        }
+
+        try {
+            resultHandler.onResult(object);
+        } catch (Throwable cause) {
+            if (exceptionHandler == null) {
+                exceptionHandler = defaultExceptionHandler;
+            }
+            if (exceptionHandler != null) {
+                try {
+                    exceptionHandler.onException(cause);
+                } catch (Throwable ignored) {
+                }
+            }
+        }
+    }
+
+    private void receiveQueries(double timeout) {
+        int resultN = nativeClientReceive(nativeClientId, eventIds, events, timeout);
+        for (int i = 0; i < resultN; i++) {
+            processResult(eventIds[i], events[i]);
+            events[i] = null;
+        }
+    }
+
+    private static native long createNativeClient();
+
+    private static native void nativeClientSend(long nativeClientId, long eventId, TdApi.Function function);
+
+    private static native int nativeClientReceive(long nativeClientId, long[] eventIds, TdApi.Object[] events, double timeout);
+
+    private static native TdApi.Object nativeClientExecute(TdApi.Function function);
+
+    private static native void destroyNativeClient(long nativeClientId);
+}
diff --git a/libs/tdlib/td/example/java/org/drinkless/tdlib/Log.java b/libs/tdlib/td/example/java/org/drinkless/tdlib/Log.java
new file mode 100644
index 0000000000..c81ffbeeb7
--- /dev/null
+++ b/libs/tdlib/td/example/java/org/drinkless/tdlib/Log.java
@@ -0,0 +1,75 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+package org.drinkless.tdlib;
+
+/**
+ * Class for managing internal TDLib logging.
+ */
+public final class Log {
+    /**
+     * Changes TDLib log verbosity.
+     *
+     * @param verbosityLevel New value of log verbosity level. Must be non-negative.
+     *                       Value 0 corresponds to fatal errors,
+     *                       value 1 corresponds to java.util.logging.Level.SEVERE,
+     *                       value 2 corresponds to java.util.logging.Level.WARNING,
+     *                       value 3 corresponds to java.util.logging.Level.INFO,
+     *                       value 4 corresponds to java.util.logging.Level.FINE,
+     *                       value 5 corresponds to java.util.logging.Level.FINER,
+     *                       value greater than 5 can be used to enable even more logging.
+     *                       Default value of the log verbosity level is 5.
+     */
+    public static native void setVerbosityLevel(int verbosityLevel);
+
+    /**
+     * Sets file path for writing TDLib internal log. By default TDLib writes logs to the System.err.
+     * Use this method to write the log to a file instead.
+     *
+     * @param filePath Path to a file for writing TDLib internal log. Use an empty path to
+     *                 switch back to logging to the System.err.
+     * @return whether opening the log file succeeded.
+     */
+    public static native boolean setFilePath(String filePath);
+
+    /**
+     * Changes maximum size of TDLib log file.
+     *
+     * @param maxFileSize Maximum size of the file to where the internal TDLib log is written
+     *                    before the file will be auto-rotated. Must be positive. Defaults to 10 MB.
+     */
+    public static native void setMaxFileSize(long maxFileSize);
+
+    /**
+     * This function is called from the JNI when a fatal error happens to provide a better error message.
+     * The function does not return.
+     *
+     * @param errorMessage Error message.
+     */
+    private static void onFatalError(String errorMessage) {
+        class ThrowError implements Runnable {
+            private ThrowError(String errorMessage) {
+                this.errorMessage = errorMessage;
+            }
+
+            @Override
+            public void run() {
+                throw new RuntimeException("TDLib fatal error: " + errorMessage);
+            }
+
+            private final String errorMessage;
+        }
+
+        new Thread(new ThrowError(errorMessage), "TDLib fatal error thread").start();
+        while (true) {
+            try {
+                Thread.sleep(1000);     // milliseconds
+            } catch (InterruptedException ex) {
+                Thread.currentThread().interrupt();
+            }
+        }
+    }
+}
diff --git a/libs/tdlib/td/example/java/org/drinkless/tdlib/example/Example.java b/libs/tdlib/td/example/java/org/drinkless/tdlib/example/Example.java
new file mode 100644
index 0000000000..831de88f1d
--- /dev/null
+++ b/libs/tdlib/td/example/java/org/drinkless/tdlib/example/Example.java
@@ -0,0 +1,533 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+package org.drinkless.tdlib.example;
+
+import org.drinkless.tdlib.Client;
+import org.drinkless.tdlib.Log;
+import org.drinkless.tdlib.TdApi;
+
+import java.io.IOError;
+import java.io.IOException;
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.util.NavigableSet;
+import java.util.TreeSet;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.locks.Condition;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
+/**
+ * Example class for TDLib usage from Java.
+ */
+public final class Example {
+    private static Client client = null;
+
+    private static TdApi.AuthorizationState authorizationState = null;
+    private static volatile boolean haveAuthorization = false;
+    private static volatile boolean quiting = false;
+
+    private static final Client.ResultHandler defaultHandler = new DefaultHandler();
+
+    private static final Lock authorizationLock = new ReentrantLock();
+    private static final Condition gotAuthorization = authorizationLock.newCondition();
+
+    private static final ConcurrentMap<Integer, TdApi.User> users = new ConcurrentHashMap<Integer, TdApi.User>();
+    private static final ConcurrentMap<Integer, TdApi.BasicGroup> basicGroups = new ConcurrentHashMap<Integer, TdApi.BasicGroup>();
+    private static final ConcurrentMap<Integer, TdApi.Supergroup> supergroups = new ConcurrentHashMap<Integer, TdApi.Supergroup>();
+    private static final ConcurrentMap<Integer, TdApi.SecretChat> secretChats = new ConcurrentHashMap<Integer, TdApi.SecretChat>();
+
+    private static final ConcurrentMap<Long, TdApi.Chat> chats = new ConcurrentHashMap<Long, TdApi.Chat>();
+    private static final NavigableSet<OrderedChat> chatList = new TreeSet<OrderedChat>();
+    private static boolean haveFullChatList = false;
+
+    private static final ConcurrentMap<Integer, TdApi.UserFullInfo> usersFullInfo = new ConcurrentHashMap<Integer, TdApi.UserFullInfo>();
+    private static final ConcurrentMap<Integer, TdApi.BasicGroupFullInfo> basicGroupsFullInfo = new ConcurrentHashMap<Integer, TdApi.BasicGroupFullInfo>();
+    private static final ConcurrentMap<Integer, TdApi.SupergroupFullInfo> supergroupsFullInfo = new ConcurrentHashMap<Integer, TdApi.SupergroupFullInfo>();
+
+    private static final String newLine = System.getProperty("line.separator");
+    private static final String commandsLine = "Enter command (gcs - GetChats, gc <chatId> - GetChat, me - GetMe, sm <chatId> <message> - SendMessage, lo - LogOut, q - Quit): ";
+    private static volatile String currentPrompt = null;
+
+    static {
+        System.loadLibrary("tdjni");
+    }
+
+    private static void print(String str) {
+        if (currentPrompt != null) {
+            System.out.println("");
+        }
+        System.out.println(str);
+        if (currentPrompt != null) {
+            System.out.print(currentPrompt);
+        }
+    }
+
+    private static void setChatOrder(TdApi.Chat chat, long order) {
+        synchronized (chatList) {
+            if (chat.order != 0) {
+                boolean isRemoved = chatList.remove(new OrderedChat(chat.order, chat.id));
+                assert isRemoved;
+            }
+
+            chat.order = order;
+
+            if (chat.order != 0) {
+                boolean isAdded = chatList.add(new OrderedChat(chat.order, chat.id));
+                assert isAdded;
+            }
+        }
+    }
+
+    private static void onAuthorizationStateUpdated(TdApi.AuthorizationState authorizationState) {
+        if (authorizationState != null) {
+            Example.authorizationState = authorizationState;
+        }
+        switch (Example.authorizationState.getConstructor()) {
+            case TdApi.AuthorizationStateWaitTdlibParameters.CONSTRUCTOR:
+                TdApi.TdlibParameters parameters = new TdApi.TdlibParameters();
+                parameters.databaseDirectory = "tdlib";
+                parameters.useMessageDatabase = true;
+                parameters.useSecretChats = true;
+                parameters.apiId = 94575;
+                parameters.apiHash = "a3406de8d171bb422bb6ddf3bbd800e2";
+                parameters.systemLanguageCode = "en";
+                parameters.deviceModel = "Desktop";
+                parameters.systemVersion = "Unknown";
+                parameters.applicationVersion = "1.0";
+                parameters.enableStorageOptimizer = true;
+
+                client.send(new TdApi.SetTdlibParameters(parameters), new AuthorizationRequestHandler());
+                break;
+            case TdApi.AuthorizationStateWaitEncryptionKey.CONSTRUCTOR:
+                client.send(new TdApi.CheckDatabaseEncryptionKey(), new AuthorizationRequestHandler());
+                break;
+            case TdApi.AuthorizationStateWaitPhoneNumber.CONSTRUCTOR: {
+                String phoneNumber = promptString("Please enter phone number: ");
+                client.send(new TdApi.SetAuthenticationPhoneNumber(phoneNumber, false, false), new AuthorizationRequestHandler());
+                break;
+            }
+            case TdApi.AuthorizationStateWaitCode.CONSTRUCTOR: {
+                String code = promptString("Please enter authentication code: ");
+                client.send(new TdApi.CheckAuthenticationCode(code, "", ""), new AuthorizationRequestHandler());
+                break;
+            }
+            case TdApi.AuthorizationStateWaitPassword.CONSTRUCTOR: {
+                String password = promptString("Please enter password: ");
+                client.send(new TdApi.CheckAuthenticationPassword(password), new AuthorizationRequestHandler());
+                break;
+            }
+            case TdApi.AuthorizationStateReady.CONSTRUCTOR:
+                haveAuthorization = true;
+                authorizationLock.lock();
+                try {
+                    gotAuthorization.signal();
+                } finally {
+                    authorizationLock.unlock();
+                }
+                break;
+            case TdApi.AuthorizationStateLoggingOut.CONSTRUCTOR:
+                haveAuthorization = false;
+                print("Logging out");
+                break;
+            case TdApi.AuthorizationStateClosing.CONSTRUCTOR:
+                haveAuthorization = false;
+                print("Closing");
+                break;
+            case TdApi.AuthorizationStateClosed.CONSTRUCTOR:
+                print("Closed");
+                if (!quiting) {
+                    client = Client.create(new UpdatesHandler(), null, null); // recreate client after previous has closed
+                }
+                break;
+            default:
+                System.err.println("Unsupported authorization state:" + newLine + Example.authorizationState);
+        }
+    }
+
+    private static int toInt(String arg) {
+        int result = 0;
+        try {
+            result = Integer.parseInt(arg);
+        } catch (NumberFormatException ignored) {
+        }
+        return result;
+    }
+
+    private static long getChatId(String arg) {
+        long chatId = 0;
+        try {
+            chatId = Long.parseLong(arg);
+        } catch (NumberFormatException ignored) {
+        }
+        return chatId;
+    }
+
+    private static String promptString(String prompt) {
+        System.out.print(prompt);
+        currentPrompt = prompt;
+        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
+        String str = "";
+        try {
+            str = reader.readLine();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        currentPrompt = null;
+        return str;
+    }
+
+    private static void getCommand() {
+        String command = promptString(commandsLine);
+        String[] commands = command.split(" ", 2);
+        try {
+            switch (commands[0]) {
+                case "gcs": {
+                    int limit = 20;
+                    if (commands.length > 1) {
+                        limit = toInt(commands[1]);
+                    }
+                    getChatList(limit);
+                    break;
+                }
+                case "gc":
+                    client.send(new TdApi.GetChat(getChatId(commands[1])), defaultHandler);
+                    break;
+                case "me":
+                    client.send(new TdApi.GetMe(), defaultHandler);
+                    break;
+                case "sm": {
+                    String[] args = commands[1].split(" ", 2);
+                    sendMessage(getChatId(args[0]), args[1]);
+                    break;
+                }
+                case "lo":
+                    haveAuthorization = false;
+                    client.send(new TdApi.LogOut(), defaultHandler);
+                    break;
+                case "q":
+                    quiting = true;
+                    haveAuthorization = false;
+                    client.send(new TdApi.Close(), defaultHandler);
+                    break;
+                default:
+                    System.err.println("Unsupported command: " + command);
+            }
+        } catch (ArrayIndexOutOfBoundsException e) {
+            print("Not enough arguments");
+        }
+    }
+
+    private static void getChatList(final int limit) {
+        synchronized (chatList) {
+            if (!haveFullChatList && limit > chatList.size()) {
+                // have enough chats in the chat list or chat list is too small
+                long offsetOrder = Long.MAX_VALUE;
+                long offsetChatId = 0;
+                if (!chatList.isEmpty()) {
+                    OrderedChat last = chatList.last();
+                    offsetOrder = last.order;
+                    offsetChatId = last.chatId;
+                }
+                client.send(new TdApi.GetChats(offsetOrder, offsetChatId, limit - chatList.size()), new Client.ResultHandler() {
+                    @Override
+                    public void onResult(TdApi.Object object) {
+                        switch (object.getConstructor()) {
+                            case TdApi.Error.CONSTRUCTOR:
+                                System.err.println("Receive an error for GetChats:" + newLine + object);
+                                break;
+                            case TdApi.Chats.CONSTRUCTOR:
+                                long[] chatIds = ((TdApi.Chats) object).chatIds;
+                                if (chatIds.length == 0) {
+                                    synchronized (chatList) {
+                                        haveFullChatList = true;
+                                    }
+                                }
+                                // chats had already been received through updates, let's retry request
+                                getChatList(limit);
+                                break;
+                            default:
+                                System.err.println("Receive wrong response from TDLib:" + newLine + object);
+                        }
+                    }
+                });
+                return;
+            }
+
+            // have enough chats in the chat list to answer request
+            java.util.Iterator<OrderedChat> iter = chatList.iterator();
+            System.out.println();
+            System.out.println("First " + limit + " chat(s) out of " + chatList.size() + " known chat(s):");
+            for (int i = 0; i < limit; i++) {
+                long chatId = iter.next().chatId;
+                TdApi.Chat chat = chats.get(chatId);
+                synchronized (chat) {
+                    System.out.println(chatId + ": " + chat.title);
+                }
+            }
+            print("");
+        }
+    }
+
+    private static void sendMessage(long chatId, String message) {
+        // initialize reply markup just for testing
+        TdApi.InlineKeyboardButton[] row = {new TdApi.InlineKeyboardButton("https://telegram.org?1", new TdApi.InlineKeyboardButtonTypeUrl()), new TdApi.InlineKeyboardButton("https://telegram.org?2", new TdApi.InlineKeyboardButtonTypeUrl()), new TdApi.InlineKeyboardButton("https://telegram.org?3", new TdApi.InlineKeyboardButtonTypeUrl())};
+        TdApi.ReplyMarkup replyMarkup = new TdApi.ReplyMarkupInlineKeyboard(new TdApi.InlineKeyboardButton[][]{row, row, row});
+
+        TdApi.InputMessageContent content = new TdApi.InputMessageText(new TdApi.FormattedText(message, null), false, true);
+        client.send(new TdApi.SendMessage(chatId, 0, false, false, replyMarkup, content), defaultHandler);
+    }
+
+    public static void main(String[] args) throws InterruptedException {
+        // disable TDLib log
+        Log.setVerbosityLevel(0);
+        if (!Log.setFilePath("tdlib.log")) {
+            throw new IOError(new IOException("Write access to the current directory is required"));
+        }
+
+        // create client
+        client = Client.create(new UpdatesHandler(), null, null);
+
+        // test Client.execute
+        defaultHandler.onResult(Client.execute(new TdApi.GetTextEntities("@telegram /test_command https://telegram.org telegram.me @gif @test")));
+
+        // main loop
+        while (!quiting) {
+            // await authorization
+            authorizationLock.lock();
+            try {
+                while (!haveAuthorization) {
+                    gotAuthorization.await();
+                }
+            } finally {
+                authorizationLock.unlock();
+            }
+
+            while (haveAuthorization) {
+                getCommand();
+            }
+        }
+    }
+
+    private static class OrderedChat implements Comparable<OrderedChat> {
+        final long order;
+        final long chatId;
+
+        OrderedChat(long order, long chatId) {
+            this.order = order;
+            this.chatId = chatId;
+        }
+
+        @Override
+        public int compareTo(OrderedChat o) {
+            if (this.order != o.order) {
+                return o.order < this.order ? -1 : 1;
+            }
+            if (this.chatId != o.chatId) {
+                return o.chatId < this.chatId ? -1 : 1;
+            }
+            return 0;
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            OrderedChat o = (OrderedChat) obj;
+            return this.order == o.order && this.chatId == o.chatId;
+        }
+    }
+
+    private static class DefaultHandler implements Client.ResultHandler {
+        @Override
+        public void onResult(TdApi.Object object) {
+            print(object.toString());
+        }
+    }
+
+    private static class UpdatesHandler implements Client.ResultHandler {
+        @Override
+        public void onResult(TdApi.Object object) {
+            switch (object.getConstructor()) {
+                case TdApi.UpdateAuthorizationState.CONSTRUCTOR:
+                    onAuthorizationStateUpdated(((TdApi.UpdateAuthorizationState) object).authorizationState);
+                    break;
+
+                case TdApi.UpdateUser.CONSTRUCTOR:
+                    TdApi.UpdateUser updateUser = (TdApi.UpdateUser) object;
+                    users.put(updateUser.user.id, updateUser.user);
+                    break;
+                case TdApi.UpdateUserStatus.CONSTRUCTOR:  {
+                    TdApi.UpdateUserStatus updateUserStatus = (TdApi.UpdateUserStatus) object;
+                    TdApi.User user = users.get(updateUserStatus.userId);
+                    synchronized (user) {
+                        user.status = updateUserStatus.status;
+                    }
+                    break;
+                }
+                case TdApi.UpdateBasicGroup.CONSTRUCTOR:
+                    TdApi.UpdateBasicGroup updateBasicGroup = (TdApi.UpdateBasicGroup) object;
+                    basicGroups.put(updateBasicGroup.basicGroup.id, updateBasicGroup.basicGroup);
+                    break;
+                case TdApi.UpdateSupergroup.CONSTRUCTOR:
+                    TdApi.UpdateSupergroup updateSupergroup = (TdApi.UpdateSupergroup) object;
+                    supergroups.put(updateSupergroup.supergroup.id, updateSupergroup.supergroup);
+                    break;
+                case TdApi.UpdateSecretChat.CONSTRUCTOR:
+                    TdApi.UpdateSecretChat updateSecretChat = (TdApi.UpdateSecretChat) object;
+                    secretChats.put(updateSecretChat.secretChat.id, updateSecretChat.secretChat);
+                    break;
+
+                case TdApi.UpdateNewChat.CONSTRUCTOR: {
+                    TdApi.UpdateNewChat updateNewChat = (TdApi.UpdateNewChat) object;
+                    TdApi.Chat chat = updateNewChat.chat;
+                    synchronized (chat) {
+                        chats.put(chat.id, chat);
+
+                        long order = chat.order;
+                        chat.order = 0;
+                        setChatOrder(chat, order);
+                    }
+                    break;
+                }
+                case TdApi.UpdateChatTitle.CONSTRUCTOR: {
+                    TdApi.UpdateChatTitle updateChat = (TdApi.UpdateChatTitle) object;
+                    TdApi.Chat chat = chats.get(updateChat.chatId);
+                    synchronized (chat) {
+                        chat.title = updateChat.title;
+                    }
+                    break;
+                }
+                case TdApi.UpdateChatPhoto.CONSTRUCTOR: {
+                    TdApi.UpdateChatPhoto updateChat = (TdApi.UpdateChatPhoto) object;
+                    TdApi.Chat chat = chats.get(updateChat.chatId);
+                    synchronized (chat) {
+                        chat.photo = updateChat.photo;
+                    }
+                    break;
+                }
+                case TdApi.UpdateChatLastMessage.CONSTRUCTOR: {
+                    TdApi.UpdateChatLastMessage updateChat = (TdApi.UpdateChatLastMessage) object;
+                    TdApi.Chat chat = chats.get(updateChat.chatId);
+                    synchronized (chat) {
+                        chat.lastMessage = updateChat.lastMessage;
+                        setChatOrder(chat, updateChat.order);
+                    }
+                    break;
+                }
+                case TdApi.UpdateChatOrder.CONSTRUCTOR: {
+                    TdApi.UpdateChatOrder updateChat = (TdApi.UpdateChatOrder) object;
+                    TdApi.Chat chat = chats.get(updateChat.chatId);
+                    synchronized (chat) {
+                        setChatOrder(chat, updateChat.order);
+                    }
+                    break;
+                }
+                case TdApi.UpdateChatIsPinned.CONSTRUCTOR: {
+                    TdApi.UpdateChatIsPinned updateChat = (TdApi.UpdateChatIsPinned) object;
+                    TdApi.Chat chat = chats.get(updateChat.chatId);
+                    synchronized (chat) {
+                        chat.isPinned = updateChat.isPinned;
+                        setChatOrder(chat, updateChat.order);
+                    }
+                    break;
+                }
+                case TdApi.UpdateChatReadInbox.CONSTRUCTOR: {
+                    TdApi.UpdateChatReadInbox updateChat = (TdApi.UpdateChatReadInbox) object;
+                    TdApi.Chat chat = chats.get(updateChat.chatId);
+                    synchronized (chat) {
+                        chat.lastReadInboxMessageId = updateChat.lastReadInboxMessageId;
+                        chat.unreadCount = updateChat.unreadCount;
+                    }
+                    break;
+                }
+                case TdApi.UpdateChatReadOutbox.CONSTRUCTOR: {
+                    TdApi.UpdateChatReadOutbox updateChat = (TdApi.UpdateChatReadOutbox) object;
+                    TdApi.Chat chat = chats.get(updateChat.chatId);
+                    synchronized (chat) {
+                        chat.lastReadOutboxMessageId = updateChat.lastReadOutboxMessageId;
+                    }
+                    break;
+                }
+                case TdApi.UpdateChatUnreadMentionCount.CONSTRUCTOR: {
+                    TdApi.UpdateChatUnreadMentionCount updateChat = (TdApi.UpdateChatUnreadMentionCount) object;
+                    TdApi.Chat chat = chats.get(updateChat.chatId);
+                    synchronized (chat) {
+                        chat.unreadMentionCount = updateChat.unreadMentionCount;
+                    }
+                    break;
+                }
+                case TdApi.UpdateMessageMentionRead.CONSTRUCTOR: {
+                    TdApi.UpdateMessageMentionRead updateChat = (TdApi.UpdateMessageMentionRead) object;
+                    TdApi.Chat chat = chats.get(updateChat.chatId);
+                    synchronized (chat) {
+                        chat.unreadMentionCount = updateChat.unreadMentionCount;
+                    }
+                    break;
+                }
+                case TdApi.UpdateChatReplyMarkup.CONSTRUCTOR: {
+                    TdApi.UpdateChatReplyMarkup updateChat = (TdApi.UpdateChatReplyMarkup) object;
+                    TdApi.Chat chat = chats.get(updateChat.chatId);
+                    synchronized (chat) {
+                        chat.replyMarkupMessageId = updateChat.replyMarkupMessageId;
+                    }
+                    break;
+                }
+                case TdApi.UpdateChatDraftMessage.CONSTRUCTOR: {
+                    TdApi.UpdateChatDraftMessage updateChat = (TdApi.UpdateChatDraftMessage) object;
+                    TdApi.Chat chat = chats.get(updateChat.chatId);
+                    synchronized (chat) {
+                        chat.draftMessage = updateChat.draftMessage;
+                        setChatOrder(chat, updateChat.order);
+                    }
+                    break;
+                }
+                case TdApi.UpdateNotificationSettings.CONSTRUCTOR: {
+                    TdApi.UpdateNotificationSettings update = (TdApi.UpdateNotificationSettings) object;
+                    if (update.scope instanceof TdApi.NotificationSettingsScopeChat) {
+                        TdApi.Chat chat = chats.get(((TdApi.NotificationSettingsScopeChat) update.scope).chatId);
+                        synchronized (chat) {
+                            chat.notificationSettings = update.notificationSettings;
+                        }
+                    }
+                    break;
+                }
+
+                case TdApi.UpdateUserFullInfo.CONSTRUCTOR:
+                    TdApi.UpdateUserFullInfo updateUserFullInfo = (TdApi.UpdateUserFullInfo) object;
+                    usersFullInfo.put(updateUserFullInfo.userId, updateUserFullInfo.userFullInfo);
+                    break;
+                case TdApi.UpdateBasicGroupFullInfo.CONSTRUCTOR:
+                    TdApi.UpdateBasicGroupFullInfo updateBasicGroupFullInfo = (TdApi.UpdateBasicGroupFullInfo) object;
+                    basicGroupsFullInfo.put(updateBasicGroupFullInfo.basicGroupId, updateBasicGroupFullInfo.basicGroupFullInfo);
+                    break;
+                case TdApi.UpdateSupergroupFullInfo.CONSTRUCTOR:
+                    TdApi.UpdateSupergroupFullInfo updateSupergroupFullInfo = (TdApi.UpdateSupergroupFullInfo) object;
+                    supergroupsFullInfo.put(updateSupergroupFullInfo.supergroupId, updateSupergroupFullInfo.supergroupFullInfo);
+                    break;
+                default:
+                    // print("Unsupported update:" + newLine + object);
+            }
+        }
+    }
+
+    private static class AuthorizationRequestHandler implements Client.ResultHandler {
+        @Override
+        public void onResult(TdApi.Object object) {
+            switch (object.getConstructor()) {
+                case TdApi.Error.CONSTRUCTOR:
+                    System.err.println("Receive an error:" + newLine + object);
+                    onAuthorizationStateUpdated(null); // repeat last action
+                    break;
+                case TdApi.Ok.CONSTRUCTOR:
+                    // result is already received through UpdateAuthorizationState, nothing to do
+                    break;
+                default:
+                    System.err.println("Receive wrong response from TDLib:" + newLine + object);
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/libs/tdlib/td/example/java/td_jni.cpp b/libs/tdlib/td/example/java/td_jni.cpp
new file mode 100644
index 0000000000..b9ba74a402
--- /dev/null
+++ b/libs/tdlib/td/example/java/td_jni.cpp
@@ -0,0 +1,158 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include <td/telegram/Client.h>
+#include <td/telegram/Log.h>
+#include <td/telegram/td_api.h>
+
+#include <td/tl/tl_jni_object.h>
+
+#include <cstdint>
+#include <cstdlib>
+#include <string>
+#include <utility>
+
+namespace td_jni {
+
+static td::td_api::object_ptr<td::td_api::Function> fetch_function(JNIEnv *env, jobject function) {
+  td::jni::reset_parse_error();
+  auto result = td::td_api::Function::fetch(env, function);
+  if (td::jni::have_parse_error()) {
+    std::abort();
+  }
+  return result;
+}
+
+static td::Client *get_client(jlong client_id) {
+  return reinterpret_cast<td::Client *>(static_cast<std::uintptr_t>(client_id));
+}
+
+static jlong Client_createNativeClient(JNIEnv *env, jclass clazz) {
+  return static_cast<jlong>(reinterpret_cast<std::uintptr_t>(new td::Client()));
+}
+
+static void Client_nativeClientSend(JNIEnv *env, jclass clazz, jlong client_id, jlong id, jobject function) {
+  get_client(client_id)->send({static_cast<std::uint64_t>(id), fetch_function(env, function)});
+}
+
+static jint Client_nativeClientReceive(JNIEnv *env, jclass clazz, jlong client_id, jlongArray ids, jobjectArray events,
+                                       jdouble timeout) {
+  auto client = get_client(client_id);
+  jsize events_size = env->GetArrayLength(ids);  // ids and events size must be of equal size
+  jsize result_size = 0;
+
+  auto response = client->receive(timeout);
+  while (response.object && result_size < events_size) {
+    jlong result_id = static_cast<jlong>(response.id);
+    env->SetLongArrayRegion(ids, result_size, 1, &result_id);
+
+    jobject object;
+    response.object->store(env, object);
+    env->SetObjectArrayElement(events, result_size, object);
+    env->DeleteLocalRef(object);
+
+    result_size++;
+    response = client->receive(0);
+  }
+  return result_size;
+}
+
+static jobject Client_nativeClientExecute(JNIEnv *env, jclass clazz, jobject function) {
+  jobject result;
+  td::Client::execute({0, fetch_function(env, function)}).object->store(env, result);
+  return result;
+}
+
+static void Client_destroyNativeClient(JNIEnv *env, jclass clazz, jlong client_id) {
+  delete get_client(client_id);
+}
+
+static void Log_setVerbosityLevel(JNIEnv *env, jclass clazz, jint new_log_verbosity_level) {
+  td::Log::set_verbosity_level(static_cast<int>(new_log_verbosity_level));
+}
+
+static jboolean Log_setFilePath(JNIEnv *env, jclass clazz, jstring file_path) {
+  return td::Log::set_file_path(td::jni::from_jstring(env, file_path)) ? JNI_TRUE : JNI_FALSE;
+}
+
+static void Log_setMaxFileSize(JNIEnv *env, jclass clazz, jlong max_file_size) {
+  td::Log::set_max_file_size(max_file_size);
+}
+
+static jstring Object_toString(JNIEnv *env, jobject object) {
+  return td::jni::to_jstring(env, to_string(td::td_api::Object::fetch(env, object)));
+}
+
+static jstring Function_toString(JNIEnv *env, jobject object) {
+  return td::jni::to_jstring(env, to_string(td::td_api::Function::fetch(env, object)));
+}
+
+static constexpr jint JAVA_VERSION = JNI_VERSION_1_6;
+static JavaVM *java_vm;
+static jclass log_class;
+
+static void on_fatal_error(const char *error_message) {
+  auto env = td::jni::get_jni_env(java_vm, JAVA_VERSION);
+  jmethodID on_fatal_error_method = env->GetStaticMethodID(log_class, "onFatalError", "(Ljava/lang/String;)V");
+  if (env && on_fatal_error_method) {
+    jstring error_str = td::jni::to_jstring(env.get(), error_message);
+    env->CallStaticVoidMethod(log_class, on_fatal_error_method, error_str);
+    if (error_str) {
+      env->DeleteLocalRef(error_str);
+    }
+  }
+}
+
+static jint register_native(JavaVM *vm) {
+  JNIEnv *env;
+  if (vm->GetEnv(reinterpret_cast<void **>(&env), JAVA_VERSION) != JNI_OK) {
+    return -1;
+  }
+
+  java_vm = vm;
+
+  auto register_method = [env](jclass clazz, std::string name, std::string signature, auto function_ptr) {
+    td::jni::register_native_method(env, clazz, std::move(name), std::move(signature),
+                                    reinterpret_cast<void *>(function_ptr));
+  };
+
+  auto client_class = td::jni::get_jclass(env, PACKAGE_NAME "/Client");
+  log_class = td::jni::get_jclass(env, PACKAGE_NAME "/Log");
+  auto object_class = td::jni::get_jclass(env, PACKAGE_NAME "/TdApi$Object");
+  auto function_class = td::jni::get_jclass(env, PACKAGE_NAME "/TdApi$Function");
+
+#define TD_OBJECT "L" PACKAGE_NAME "/TdApi$Object;"
+#define TD_FUNCTION "L" PACKAGE_NAME "/TdApi$Function;"
+  register_method(client_class, "createNativeClient", "()J", Client_createNativeClient);
+  register_method(client_class, "nativeClientSend", "(JJ" TD_FUNCTION ")V", Client_nativeClientSend);
+  register_method(client_class, "nativeClientReceive", "(J[J[" TD_OBJECT "D)I", Client_nativeClientReceive);
+  register_method(client_class, "nativeClientExecute", "(" TD_FUNCTION ")" TD_OBJECT, Client_nativeClientExecute);
+  register_method(client_class, "destroyNativeClient", "(J)V", Client_destroyNativeClient);
+
+  register_method(log_class, "setVerbosityLevel", "(I)V", Log_setVerbosityLevel);
+  register_method(log_class, "setFilePath", "(Ljava/lang/String;)Z", Log_setFilePath);
+  register_method(log_class, "setMaxFileSize", "(J)V", Log_setMaxFileSize);
+
+  register_method(object_class, "toString", "()Ljava/lang/String;", Object_toString);
+
+  register_method(function_class, "toString", "()Ljava/lang/String;", Function_toString);
+#undef TD_FUNCTION
+#undef TD_OBJECT
+
+  td::jni::init_vars(env, PACKAGE_NAME);
+  td::td_api::Object::init_jni_vars(env, PACKAGE_NAME);
+  td::td_api::Function::init_jni_vars(env, PACKAGE_NAME);
+  td::Log::set_fatal_error_callback(on_fatal_error);
+
+  return JAVA_VERSION;
+}
+
+}  // namespace td_jni
+
+JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved) {
+  static jint jni_version = td_jni::register_native(vm);  // call_once
+  return jni_version;
+}
diff --git a/libs/tdlib/td/example/python/README.md b/libs/tdlib/td/example/python/README.md
new file mode 100644
index 0000000000..c4a4ad3768
--- /dev/null
+++ b/libs/tdlib/td/example/python/README.md
@@ -0,0 +1,11 @@
+# TDLib Python example
+
+To run this example you need to [build](https://github.com/tdlib/td#building) TDLib and copy built tdjson shared library to this directory.
+
+Then you can run the example:
+```
+python tdjson_example.py
+```
+
+Description of all available classes and methods can be found at [td_json_client](https://core.telegram.org/tdlib/docs/td__json__client_8h.html),
+[td_log](https://core.telegram.org/tdlib/docs/td__log_8h.html) and [td_api](https://core.telegram.org/tdlib/docs/td__api_8h.html) documentation.
diff --git a/libs/tdlib/td/example/python/tdjson_example.py b/libs/tdlib/td/example/python/tdjson_example.py
new file mode 100644
index 0000000000..d7b2e86fbb
--- /dev/null
+++ b/libs/tdlib/td/example/python/tdjson_example.py
@@ -0,0 +1,106 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+from ctypes.util import find_library
+from ctypes import *
+import json
+import sys
+
+# load shared library
+tdjson_path = find_library("tdjson") or "tdjson.dll"
+if tdjson_path is None:
+    print('can\'t find tdjson library')
+    quit()
+tdjson = CDLL(tdjson_path)
+
+# load TDLib functions from shared library
+td_json_client_create = tdjson.td_json_client_create
+td_json_client_create.restype = c_void_p
+td_json_client_create.argtypes = []
+
+td_json_client_receive = tdjson.td_json_client_receive
+td_json_client_receive.restype = c_char_p
+td_json_client_receive.argtypes = [c_void_p, c_double]
+
+td_json_client_send = tdjson.td_json_client_send
+td_json_client_send.restype = None
+td_json_client_send.argtypes = [c_void_p, c_char_p]
+
+td_json_client_execute = tdjson.td_json_client_execute
+td_json_client_execute.restype = c_char_p
+td_json_client_execute.argtypes = [c_void_p, c_char_p]
+
+td_json_client_destroy = tdjson.td_json_client_destroy
+td_json_client_destroy.restype = None
+td_json_client_destroy.argtypes = [c_void_p]
+
+td_set_log_file_path = tdjson.td_set_log_file_path
+td_set_log_file_path.restype = c_int
+td_set_log_file_path.argtypes = [c_char_p]
+
+td_set_log_max_file_size = tdjson.td_set_log_max_file_size
+td_set_log_max_file_size.restype = None
+td_set_log_max_file_size.argtypes = [c_longlong]
+
+td_set_log_verbosity_level = tdjson.td_set_log_verbosity_level
+td_set_log_verbosity_level.restype = None
+td_set_log_verbosity_level.argtypes = [c_int]
+
+fatal_error_callback_type = CFUNCTYPE(None, c_char_p)
+
+td_set_log_fatal_error_callback = tdjson.td_set_log_fatal_error_callback
+td_set_log_fatal_error_callback.restype = None
+td_set_log_fatal_error_callback.argtypes = [fatal_error_callback_type]
+
+# initialize TDLib log with desired parameters
+def on_fatal_error_callback(error_message):
+    print('TDLib fatal error: ', error_message)
+
+td_set_log_verbosity_level(2)
+c_on_fatal_error_callback = fatal_error_callback_type(on_fatal_error_callback)
+td_set_log_fatal_error_callback(c_on_fatal_error_callback)
+
+# create client
+client = td_json_client_create()
+
+# simple wrappers for client usage
+def td_send(query):
+    query = json.dumps(query).encode('utf-8')
+    td_json_client_send(client, query)
+
+def td_receive():
+    result = td_json_client_receive(client, 1.0)
+    if result:
+        result = json.loads(result.decode('utf-8'))
+    return result
+
+def td_execute(query):
+    query = json.dumps(query).encode('utf-8')
+    result = td_json_client_execute(client, query)
+    if result:
+        result = json.loads(result.decode('utf-8'))
+    return result
+
+# testing TDLib execute method
+print(td_execute({'@type': 'getTextEntities', 'text': '@telegram /test_command https://telegram.org telegram.me', '@extra': ['5', 7.0]}))
+
+# testing TDLib send method
+td_send({'@type': 'getAuthorizationState', '@extra': 1.01234})
+
+# main events cycle
+while True:
+    event = td_receive()
+    if event:
+        # if client is closed, we need to destroy it and create new client
+        if event['@type'] is 'updateAuthorizationState' and event['authorization_state']['@type'] is 'authorizationStateClosed':
+            break
+
+        # handle an incoming update or an answer to a previously sent request
+        print(event)
+        sys.stdout.flush()
+
+# destroy client when it is closed and isn't needed anymore
+td_json_client_destroy(client)
diff --git a/libs/tdlib/td/example/ruby/Gemfile b/libs/tdlib/td/example/ruby/Gemfile
new file mode 100644
index 0000000000..3a38ffc0a3
--- /dev/null
+++ b/libs/tdlib/td/example/ruby/Gemfile
@@ -0,0 +1,3 @@
+source 'https://rubygems.org'
+
+gem 'tdlib-ruby'
diff --git a/libs/tdlib/td/example/ruby/Gemfile.lock b/libs/tdlib/td/example/ruby/Gemfile.lock
new file mode 100644
index 0000000000..22954eddfb
--- /dev/null
+++ b/libs/tdlib/td/example/ruby/Gemfile.lock
@@ -0,0 +1,17 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    concurrent-ruby (1.0.5)
+    dry-configurable (0.7.0)
+      concurrent-ruby (~> 1.0)
+    tdlib-ruby (0.2.0)
+      dry-configurable (~> 0.7)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  tdlib-ruby
+
+BUNDLED WITH
+   1.16.1
diff --git a/libs/tdlib/td/example/ruby/example.rb b/libs/tdlib/td/example/ruby/example.rb
new file mode 100644
index 0000000000..4b29dfd53a
--- /dev/null
+++ b/libs/tdlib/td/example/ruby/example.rb
@@ -0,0 +1,61 @@
+require 'tdlib-ruby'
+
+TD.configure do |config|
+  config.lib_path = 'path/to/dir_containing_lobtdjson'
+
+  # You should obtain your own api_id and api_hash from https://my.telegram.org/apps
+  config.client.api_id = 12345
+  config.client.api_hash = '1234567890abcdefghigklmnopqrstuv'
+end
+
+TD::Api.set_log_verbosity_level(1)
+
+client = TD::Client.new
+
+begin
+  state = nil
+
+  client.on('updateAuthorizationState') do |update|
+    next unless update.dig('authorization_state', '@type') == 'authorizationStateWaitPhoneNumber'
+    state = :wait_phone
+  end
+
+  client.on('updateAuthorizationState') do |update|
+    next unless update.dig('authorization_state', '@type') == 'authorizationStateWaitCode'
+    state = :wait_code
+  end
+
+  client.on('updateAuthorizationState') do |update|
+    next unless update.dig('authorization_state', '@type') == 'authorizationStateReady'
+    state = :ready
+  end
+
+  loop do
+    case state
+    when :wait_phone
+      p 'Please, enter your phone number:'
+      phone = STDIN.gets.strip
+      params = {
+        '@type' => 'setAuthenticationPhoneNumber',
+        'phone_number' => phone
+      }
+      client.broadcast_and_receive(params)
+    when :wait_code
+      p 'Please, enter code from SMS:'
+      code = STDIN.gets.strip
+      params = {
+        '@type' => 'checkAuthenticationCode',
+        'code' => code
+      }
+      client.broadcast_and_receive(params)
+    when :ready
+      @me = client.broadcast_and_receive('@type' => 'getMe')
+      break
+    end
+  end
+
+ensure
+  client.close
+end
+
+p @me
diff --git a/libs/tdlib/td/example/swift/.gitignore b/libs/tdlib/td/example/swift/.gitignore
new file mode 100644
index 0000000000..4737be5996
--- /dev/null
+++ b/libs/tdlib/td/example/swift/.gitignore
@@ -0,0 +1,3 @@
+xcuserdata/
+*workspace/
+td/
diff --git a/libs/tdlib/td/example/swift/README.md b/libs/tdlib/td/example/swift/README.md
new file mode 100644
index 0000000000..6a333df766
--- /dev/null
+++ b/libs/tdlib/td/example/swift/README.md
@@ -0,0 +1,15 @@
+# TDLib swift MacOS example
+
+TDLib should be prebuilt and installed to local subdirectory `td/`:
+```
+cd <path to TDLib sources>
+mkdir build
+cd build
+cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX:PATH=../example/swift/td ..
+cmake --build . --target install
+```
+
+Then you can open and build the example with the latest Xcode.
+
+Description of all available classes and methods can be found at [td_json_client](https://core.telegram.org/tdlib/docs/td__json__client_8h.html),
+[td_log](https://core.telegram.org/tdlib/docs/td__log_8h.html) and [td_api](https://core.telegram.org/tdlib/docs/td__api_8h.html) documentation.
diff --git a/libs/tdlib/td/example/swift/src/main.swift b/libs/tdlib/td/example/swift/src/main.swift
new file mode 100644
index 0000000000..ac81c632b8
--- /dev/null
+++ b/libs/tdlib/td/example/swift/src/main.swift
@@ -0,0 +1,178 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+import Foundation
+
+// TDLib Client Swift binding
+class TdClient {
+    typealias Client = UnsafeMutableRawPointer
+    var client = td_json_client_create()!
+    let tdlibMainLoop = DispatchQueue(label: "TDLib")
+    let tdlibQueryQueue = DispatchQueue(label: "TDLibQuery")
+    var queryF = Dictionary<Int64, (Dictionary<String,Any>)->()>()
+    var updateF: ((Dictionary<String,Any>)->())?
+    var queryId: Int64 = 0
+
+    func queryAsync(query: [String: Any], f: ((Dictionary<String,Any>)->())? = nil) {
+        tdlibQueryQueue.async {
+            var newQuery = query
+
+            if f != nil {
+                let nextQueryId = self.queryId + 1
+                newQuery["@extra"] = nextQueryId
+                self.queryF[nextQueryId] = f
+                self.queryId = nextQueryId
+            }
+            td_json_client_send(self.client, to_json(newQuery))
+        }
+    }
+
+    func querySync(query: [String: Any]) -> Dictionary<String,Any> {
+        let semaphore = DispatchSemaphore(value:0)
+        var result = Dictionary<String,Any>()
+        queryAsync(query: query) {
+            result = $0
+            semaphore.signal()
+        }
+        semaphore.wait()
+        return result
+    }
+
+    init() {
+    }
+
+    deinit {
+        td_json_client_destroy(client)
+    }
+
+    func run(updateHandler: @escaping (Dictionary<String,Any>)->()) {
+        updateF = updateHandler
+        tdlibMainLoop.async { [weak self] in
+            while (true) {
+                if let s = self {
+                    if let res = td_json_client_receive(s.client, 10) {
+                        let event = String(cString: res)
+                        s.queryResultAsync(event)
+                    }
+                } else {
+                    break
+                }
+            }
+        }
+    }
+
+    private func queryResultAsync(_ result: String) {
+        tdlibQueryQueue.async {
+            let json = try? JSONSerialization.jsonObject(with: result.data(using: .utf8)!, options:[])
+            if let dictionary = json as? [String:Any] {
+                if let extra = dictionary["@extra"] as? Int64 {
+                    let index = self.queryF.index(forKey: extra)!
+                    self.queryF[index].value(dictionary)
+                    self.queryF.remove(at: index)
+                } else {
+                    self.updateF!(dictionary)
+                }
+            }
+        }
+    }
+}
+
+func to_json(_ obj: Any) -> String {
+    do {
+        let obj = try JSONSerialization.data(withJSONObject: obj)
+        return String(data: obj, encoding: .utf8)!
+    } catch {
+        return ""
+    }
+}
+
+
+// An example of usage
+td_set_log_verbosity_level(1);
+
+var client = TdClient()
+
+func myReadLine() -> String {
+    while (true) {
+        if let line = readLine() {
+            return line
+        }
+    }
+}
+
+func updateAuthorizationState(authorizationState: Dictionary<String, Any>) {
+    switch(authorizationState["@type"] as! String) {
+        case "authorizationStateWaitTdlibParameters":
+            client.queryAsync(query:[
+                "@type":"setTdlibParameters",
+                "parameters":[
+                    "database_directory":"tdlib",
+                    "use_message_database":true,
+                    "use_secret_chats":true,
+                    "api_id":94575,
+                    "api_hash":"a3406de8d171bb422bb6ddf3bbd800e2",
+                    "system_language_code":"en",
+                    "device_model":"Desktop",
+                    "system_version":"Unknown",
+                    "application_version":"1.0",
+                    "enable_storage_optimizer":true
+                ]
+            ]);
+
+        case "authorizationStateWaitEncryptionKey":
+            client.queryAsync(query: ["@type":"checkDatabaseEncryptionKey", "key":"cucumber"])
+
+        case "authorizationStateWaitPhoneNumber":
+            print("Enter your phone: ")
+            let phone = myReadLine()
+            client.queryAsync(query:["@type":"setAuthenticationPhoneNumber", "phone_number":phone], f:checkAuthenticationError)
+
+        case "authorizationStateWaitCode":
+            var first_name: String = ""
+            var last_name: String = ""
+            var code: String = ""
+            if let is_registered = authorizationState["is_registered"] as? Bool, is_registered {
+            } else {
+                print("Enter your first name: ")
+                first_name = myReadLine()
+                print("Enter your last name: ")
+                last_name = myReadLine()
+            }
+            print("Enter (SMS) code: ")
+            code = myReadLine()
+            client.queryAsync(query:["@type":"checkAuthenticationCode", "code":code, "first_name":first_name, "last_name":last_name], f:checkAuthenticationError)
+
+        case "authorizationStateWaitPassword":
+            print("Enter password: ")
+            let password = myReadLine()
+            client.queryAsync(query:["@type":"checkAuthenticationPassword", "password":password], f:checkAuthenticationError)
+
+        case "authorizationStateReady":
+            ()
+
+        default:
+            assert(false, "TODO: Unknown authorization state");
+    }
+}
+
+func checkAuthenticationError(error: Dictionary<String, Any>) {
+    if (error["@type"] as! String == "error") {
+        client.queryAsync(query:["@type":"getAuthorizationState"], f:updateAuthorizationState)
+    }
+}
+
+client.run {
+    let update = $0
+    print(update)
+    if update["@type"] as! String == "updateAuthorizationState" {
+        updateAuthorizationState(authorizationState: update["authorization_state"] as! Dictionary<String, Any>)
+    }
+}
+
+while true {
+    sleep(1)
+}
diff --git a/libs/tdlib/td/example/swift/src/td-Bridging-Header.h b/libs/tdlib/td/example/swift/src/td-Bridging-Header.h
new file mode 100644
index 0000000000..434ab2e4a4
--- /dev/null
+++ b/libs/tdlib/td/example/swift/src/td-Bridging-Header.h
@@ -0,0 +1,15 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "td/telegram/td_json_client.h"
+#include "td/telegram/td_log.h"
diff --git a/libs/tdlib/td/example/swift/td.xcodeproj/project.pbxproj b/libs/tdlib/td/example/swift/td.xcodeproj/project.pbxproj
new file mode 100644
index 0000000000..7b774c421c
--- /dev/null
+++ b/libs/tdlib/td/example/swift/td.xcodeproj/project.pbxproj
@@ -0,0 +1,310 @@
+// !$*UTF8*$!
+{
+	archiveVersion = 1;
+	classes = {
+	};
+	objectVersion = 46;
+	objects = {
+
+/* Begin PBXBuildFile section */
+		1F65E3A42031BF6A00F79763 /* libtdjson.dylib in Frameworks */ = {isa = PBXBuildFile; fileRef = 1F65E3A32031BF6A00F79763 /* libtdjson.dylib */; };
+		1F65E3A92031C0F000F79763 /* main.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1F65E3A82031C0F000F79763 /* main.swift */; };
+/* End PBXBuildFile section */
+
+/* Begin PBXCopyFilesBuildPhase section */
+		1FCE2CEF1EC5E1B50061661A /* CopyFiles */ = {
+			isa = PBXCopyFilesBuildPhase;
+			buildActionMask = 2147483647;
+			dstPath = /usr/share/man/man1/;
+			dstSubfolderSpec = 0;
+			files = (
+			);
+			runOnlyForDeploymentPostprocessing = 1;
+		};
+/* End PBXCopyFilesBuildPhase section */
+
+/* Begin PBXFileReference section */
+		1F65E3A32031BF6A00F79763 /* libtdjson.dylib */ = {isa = PBXFileReference; lastKnownFileType = "compiled.mach-o.dylib"; name = libtdjson.dylib; path = td/lib/libtdjson.dylib; sourceTree = "<group>"; };
+		1F65E3A82031C0F000F79763 /* main.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = main.swift; path = src/main.swift; sourceTree = SOURCE_ROOT; };
+		1F65E3AA2031C14300F79763 /* td-Bridging-Header.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = "td-Bridging-Header.h"; path = "src/td-Bridging-Header.h"; sourceTree = SOURCE_ROOT; };
+		1FCE2CF11EC5E1B50061661A /* td */ = {isa = PBXFileReference; explicitFileType = "compiled.mach-o.executable"; includeInIndex = 0; path = td; sourceTree = BUILT_PRODUCTS_DIR; };
+/* End PBXFileReference section */
+
+/* Begin PBXFrameworksBuildPhase section */
+		1FCE2CEE1EC5E1B50061661A /* Frameworks */ = {
+			isa = PBXFrameworksBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+				1F65E3A42031BF6A00F79763 /* libtdjson.dylib in Frameworks */,
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+		};
+/* End PBXFrameworksBuildPhase section */
+
+/* Begin PBXGroup section */
+		1FCE2CE81EC5E1B50061661A = {
+			isa = PBXGroup;
+			children = (
+				1FCE2CF31EC5E1B50061661A /* src */,
+				1FCE2CF21EC5E1B50061661A /* Products */,
+				1FCE2CFB1EC5E1EE0061661A /* Frameworks */,
+			);
+			sourceTree = "<group>";
+		};
+		1FCE2CF21EC5E1B50061661A /* Products */ = {
+			isa = PBXGroup;
+			children = (
+				1FCE2CF11EC5E1B50061661A /* td */,
+			);
+			name = Products;
+			sourceTree = "<group>";
+		};
+		1FCE2CF31EC5E1B50061661A /* src */ = {
+			isa = PBXGroup;
+			children = (
+				1F65E3AA2031C14300F79763 /* td-Bridging-Header.h */,
+				1F65E3A82031C0F000F79763 /* main.swift */,
+			);
+			name = src;
+			path = td;
+			sourceTree = "<group>";
+		};
+		1FCE2CFB1EC5E1EE0061661A /* Frameworks */ = {
+			isa = PBXGroup;
+			children = (
+				1F65E3A32031BF6A00F79763 /* libtdjson.dylib */,
+			);
+			name = Frameworks;
+			sourceTree = "<group>";
+		};
+/* End PBXGroup section */
+
+/* Begin PBXNativeTarget section */
+		1FCE2CF01EC5E1B50061661A /* td */ = {
+			isa = PBXNativeTarget;
+			buildConfigurationList = 1FCE2CF81EC5E1B50061661A /* Build configuration list for PBXNativeTarget "td" */;
+			buildPhases = (
+				1FCE2CED1EC5E1B50061661A /* Sources */,
+				1FCE2CEE1EC5E1B50061661A /* Frameworks */,
+				1FCE2CEF1EC5E1B50061661A /* CopyFiles */,
+			);
+			buildRules = (
+			);
+			dependencies = (
+			);
+			name = td;
+			productName = td;
+			productReference = 1FCE2CF11EC5E1B50061661A /* td */;
+			productType = "com.apple.product-type.tool";
+		};
+/* End PBXNativeTarget section */
+
+/* Begin PBXProject section */
+		1FCE2CE91EC5E1B50061661A /* Project object */ = {
+			isa = PBXProject;
+			attributes = {
+				LastSwiftUpdateCheck = 0830;
+				LastUpgradeCheck = 0920;
+				ORGANIZATIONNAME = "Arseny Smirnov ";
+				TargetAttributes = {
+					1FCE2CF01EC5E1B50061661A = {
+						CreatedOnToolsVersion = 8.3.2;
+						LastSwiftMigration = 0920;
+						ProvisioningStyle = Automatic;
+					};
+				};
+			};
+			buildConfigurationList = 1FCE2CEC1EC5E1B50061661A /* Build configuration list for PBXProject "td" */;
+			compatibilityVersion = "Xcode 3.2";
+			developmentRegion = English;
+			hasScannedForEncodings = 0;
+			knownRegions = (
+				en,
+			);
+			mainGroup = 1FCE2CE81EC5E1B50061661A;
+			productRefGroup = 1FCE2CF21EC5E1B50061661A /* Products */;
+			projectDirPath = "";
+			projectRoot = "";
+			targets = (
+				1FCE2CF01EC5E1B50061661A /* td */,
+			);
+		};
+/* End PBXProject section */
+
+/* Begin PBXSourcesBuildPhase section */
+		1FCE2CED1EC5E1B50061661A /* Sources */ = {
+			isa = PBXSourcesBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+				1F65E3A92031C0F000F79763 /* main.swift in Sources */,
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+		};
+/* End PBXSourcesBuildPhase section */
+
+/* Begin XCBuildConfiguration section */
+		1FCE2CF61EC5E1B50061661A /* Debug */ = {
+			isa = XCBuildConfiguration;
+			buildSettings = {
+				ALWAYS_SEARCH_USER_PATHS = NO;
+				CLANG_ANALYZER_NONNULL = YES;
+				CLANG_ANALYZER_NUMBER_OBJECT_CONVERSION = YES_AGGRESSIVE;
+				CLANG_CXX_LANGUAGE_STANDARD = "gnu++0x";
+				CLANG_CXX_LIBRARY = "libc++";
+				CLANG_ENABLE_MODULES = YES;
+				CLANG_ENABLE_OBJC_ARC = YES;
+				CLANG_WARN_BLOCK_CAPTURE_AUTORELEASING = YES;
+				CLANG_WARN_BOOL_CONVERSION = YES;
+				CLANG_WARN_COMMA = YES;
+				CLANG_WARN_CONSTANT_CONVERSION = YES;
+				CLANG_WARN_DIRECT_OBJC_ISA_USAGE = YES_ERROR;
+				CLANG_WARN_DOCUMENTATION_COMMENTS = YES;
+				CLANG_WARN_EMPTY_BODY = YES;
+				CLANG_WARN_ENUM_CONVERSION = YES;
+				CLANG_WARN_INFINITE_RECURSION = YES;
+				CLANG_WARN_INT_CONVERSION = YES;
+				CLANG_WARN_NON_LITERAL_NULL_CONVERSION = YES;
+				CLANG_WARN_OBJC_LITERAL_CONVERSION = YES;
+				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
+				CLANG_WARN_RANGE_LOOP_ANALYSIS = YES;
+				CLANG_WARN_STRICT_PROTOTYPES = YES;
+				CLANG_WARN_SUSPICIOUS_MOVE = YES;
+				CLANG_WARN_UNREACHABLE_CODE = YES;
+				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
+				CODE_SIGN_IDENTITY = "-";
+				COPY_PHASE_STRIP = NO;
+				DEBUG_INFORMATION_FORMAT = dwarf;
+				ENABLE_STRICT_OBJC_MSGSEND = YES;
+				ENABLE_TESTABILITY = YES;
+				GCC_C_LANGUAGE_STANDARD = gnu99;
+				GCC_DYNAMIC_NO_PIC = NO;
+				GCC_NO_COMMON_BLOCKS = YES;
+				GCC_OPTIMIZATION_LEVEL = 0;
+				GCC_PREPROCESSOR_DEFINITIONS = (
+					"DEBUG=1",
+					"$(inherited)",
+				);
+				GCC_WARN_64_TO_32_BIT_CONVERSION = YES;
+				GCC_WARN_ABOUT_RETURN_TYPE = YES_ERROR;
+				GCC_WARN_UNDECLARED_SELECTOR = YES;
+				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
+				GCC_WARN_UNUSED_FUNCTION = YES;
+				GCC_WARN_UNUSED_VARIABLE = YES;
+				MACOSX_DEPLOYMENT_TARGET = 10.12;
+				MTL_ENABLE_DEBUG_INFO = YES;
+				ONLY_ACTIVE_ARCH = YES;
+				SDKROOT = macosx;
+				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_SWIFT3_OBJC_INFERENCE = Default;
+			};
+			name = Debug;
+		};
+		1FCE2CF71EC5E1B50061661A /* Release */ = {
+			isa = XCBuildConfiguration;
+			buildSettings = {
+				ALWAYS_SEARCH_USER_PATHS = NO;
+				CLANG_ANALYZER_NONNULL = YES;
+				CLANG_ANALYZER_NUMBER_OBJECT_CONVERSION = YES_AGGRESSIVE;
+				CLANG_CXX_LANGUAGE_STANDARD = "gnu++0x";
+				CLANG_CXX_LIBRARY = "libc++";
+				CLANG_ENABLE_MODULES = YES;
+				CLANG_ENABLE_OBJC_ARC = YES;
+				CLANG_WARN_BLOCK_CAPTURE_AUTORELEASING = YES;
+				CLANG_WARN_BOOL_CONVERSION = YES;
+				CLANG_WARN_COMMA = YES;
+				CLANG_WARN_CONSTANT_CONVERSION = YES;
+				CLANG_WARN_DIRECT_OBJC_ISA_USAGE = YES_ERROR;
+				CLANG_WARN_DOCUMENTATION_COMMENTS = YES;
+				CLANG_WARN_EMPTY_BODY = YES;
+				CLANG_WARN_ENUM_CONVERSION = YES;
+				CLANG_WARN_INFINITE_RECURSION = YES;
+				CLANG_WARN_INT_CONVERSION = YES;
+				CLANG_WARN_NON_LITERAL_NULL_CONVERSION = YES;
+				CLANG_WARN_OBJC_LITERAL_CONVERSION = YES;
+				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
+				CLANG_WARN_RANGE_LOOP_ANALYSIS = YES;
+				CLANG_WARN_STRICT_PROTOTYPES = YES;
+				CLANG_WARN_SUSPICIOUS_MOVE = YES;
+				CLANG_WARN_UNREACHABLE_CODE = YES;
+				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
+				CODE_SIGN_IDENTITY = "-";
+				COPY_PHASE_STRIP = NO;
+				DEBUG_INFORMATION_FORMAT = "dwarf-with-dsym";
+				ENABLE_NS_ASSERTIONS = NO;
+				ENABLE_STRICT_OBJC_MSGSEND = YES;
+				GCC_C_LANGUAGE_STANDARD = gnu99;
+				GCC_NO_COMMON_BLOCKS = YES;
+				GCC_WARN_64_TO_32_BIT_CONVERSION = YES;
+				GCC_WARN_ABOUT_RETURN_TYPE = YES_ERROR;
+				GCC_WARN_UNDECLARED_SELECTOR = YES;
+				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
+				GCC_WARN_UNUSED_FUNCTION = YES;
+				GCC_WARN_UNUSED_VARIABLE = YES;
+				MACOSX_DEPLOYMENT_TARGET = 10.12;
+				MTL_ENABLE_DEBUG_INFO = NO;
+				SDKROOT = macosx;
+				SWIFT_OPTIMIZATION_LEVEL = "-Owholemodule";
+				SWIFT_SWIFT3_OBJC_INFERENCE = Default;
+			};
+			name = Release;
+		};
+		1FCE2CF91EC5E1B50061661A /* Debug */ = {
+			isa = XCBuildConfiguration;
+			buildSettings = {
+				CLANG_ENABLE_MODULES = YES;
+				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/../Frameworks @loader_path/../Frameworks $(PROJECT_DIR)/lib";
+				LIBRARY_SEARCH_PATHS = (
+					"$(inherited)",
+					"$(PROJECT_DIR)/td/lib",
+				);
+				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_OBJC_BRIDGING_HEADER = "src/td-Bridging-Header.h";
+				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_SWIFT3_OBJC_INFERENCE = Default;
+				SWIFT_VERSION = 4.0;
+				USER_HEADER_SEARCH_PATHS = td/include/;
+			};
+			name = Debug;
+		};
+		1FCE2CFA1EC5E1B50061661A /* Release */ = {
+			isa = XCBuildConfiguration;
+			buildSettings = {
+				CLANG_ENABLE_MODULES = YES;
+				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/../Frameworks @loader_path/../Frameworks $(PROJECT_DIR)/lib";
+				LIBRARY_SEARCH_PATHS = (
+					"$(inherited)",
+					"$(PROJECT_DIR)/td/lib",
+				);
+				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_OBJC_BRIDGING_HEADER = "src/td-Bridging-Header.h";
+				SWIFT_SWIFT3_OBJC_INFERENCE = Default;
+				SWIFT_VERSION = 4.0;
+				USER_HEADER_SEARCH_PATHS = td/include/;
+			};
+			name = Release;
+		};
+/* End XCBuildConfiguration section */
+
+/* Begin XCConfigurationList section */
+		1FCE2CEC1EC5E1B50061661A /* Build configuration list for PBXProject "td" */ = {
+			isa = XCConfigurationList;
+			buildConfigurations = (
+				1FCE2CF61EC5E1B50061661A /* Debug */,
+				1FCE2CF71EC5E1B50061661A /* Release */,
+			);
+			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
+		};
+		1FCE2CF81EC5E1B50061661A /* Build configuration list for PBXNativeTarget "td" */ = {
+			isa = XCConfigurationList;
+			buildConfigurations = (
+				1FCE2CF91EC5E1B50061661A /* Debug */,
+				1FCE2CFA1EC5E1B50061661A /* Release */,
+			);
+			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
+		};
+/* End XCConfigurationList section */
+	};
+	rootObject = 1FCE2CE91EC5E1B50061661A /* Project object */;
+}
diff --git a/libs/tdlib/td/example/uwp/LICENSE_1_0.txt b/libs/tdlib/td/example/uwp/LICENSE_1_0.txt
new file mode 100644
index 0000000000..36b7cd93cd
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/LICENSE_1_0.txt
@@ -0,0 +1,23 @@
+Boost Software License - Version 1.0 - August 17th, 2003
+
+Permission is hereby granted, free of charge, to any person or organization
+obtaining a copy of the software and accompanying documentation covered by
+this license (the "Software") to use, reproduce, display, distribute,
+execute, and transmit the Software, and to prepare derivative works of the
+Software, and to permit third-parties to whom the Software is furnished to
+do so, all subject to the following:
+
+The copyright notices in the Software and this entire statement, including
+the above license grant, this restriction and the following disclaimer,
+must be included in all copies of the Software, in whole or in part, and
+all derivative works of the Software, unless such copies or derivative
+works are solely in the form of machine-executable object code generated by
+a source language processor.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
diff --git a/libs/tdlib/td/example/uwp/README.md b/libs/tdlib/td/example/uwp/README.md
new file mode 100644
index 0000000000..e7bb9b821b
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/README.md
@@ -0,0 +1,28 @@
+# TDLib Universal Windows Platform example
+
+This is an example of building TDLib SDK for Universal Windows Platform and an example of its usage from C#.
+
+## Building SDK
+
+* Download and install Microsoft Visual Studio 2015+ with Windows 10 SDK. We recommend to use the latest available versions of Microsoft Visual Studio and Windows 10 SDK.
+* Download and install [CMake](https://cmake.org/download/).
+* Install [vcpkg](https://github.com/Microsoft/vcpkg#quick-start) or update it to the latest version using `vcpkg update` and following received instructions.
+* Install `zlib` and `openssl` for all UWP architectures using `vcpkg`:
+```
+C:\src\vcpkg> .\vcpkg.exe install openssl:arm-uwp openssl:x64-uwp openssl:x86-uwp zlib:arm-uwp zlib:x64-uwp zlib:x86-uwp
+```
+* (Optional. For XML documentation generation.) Download [PHP](https://windows.php.net/download#php-7.2). Add the path to php.exe to the PATH environment variable.
+* Download and install [gperf](https://sourceforge.net/projects/gnuwin32/files/gperf/3.0.1/). Add the path to gperf.exe to the PATH environment variable.
+* Download and install [7-Zip](http://www.7-zip.org/download.html) archiver, which is used by the `build.ps1` script to create a Telegram.Td.UWP Visual Studio Extension. Add the path to 7z.exe to the PATH environment variable.
+  Alternatively `build.ps1` supports compressing using [WinRAR](https://en.wikipedia.org/wiki/WinRAR) with option `-compress winrar` and compressing using [zip](http://gnuwin32.sourceforge.net/packages/zip.htm) with `-compress zip`.
+* Build `TDLib` using provided `build.ps1` script (TDLib should be built 6 times for multiple platforms in Debug and Release configurations, so it make take few hours). Pass path to vcpkg.exe as `-vcpkg-root` argument:
+```
+powershell -ExecutionPolicy ByPass .\build.ps1 -vcpkg_root C:\src\vcpkg
+```
+If you need to restart the build from scratch, call `.\build.ps1 -mode clean` first.
+* Install Visual Studio Extension "TDLib for Universal Windows Platform" located at `build-uwp\vsix\tdlib.vsix`, which was created on the previous step by `build.ps1` script.
+
+Now `TDLib` can be freely used from any UWP project, built in Visual Studio.
+
+## Example of usage
+The `app/` directory contains a simple example of a C# application for Universal Windows Platform. Just open it with Visual Studio 2015 or 2017 and run.
diff --git a/libs/tdlib/td/example/uwp/SDKManifest.xml b/libs/tdlib/td/example/uwp/SDKManifest.xml
new file mode 100644
index 0000000000..d6896fcb65
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/SDKManifest.xml
@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<FileList
+    DisplayName="TDLib for Universal Windows Platform"
+    ProductFamilyName="Telegram.Td.UWP"
+    MoreInfo="https://core.telegram.org/tdlib"
+    MinVSVersion="14.0"
+    AppliesTo="WindowsAppContainer"
+    DependsOn="Microsoft.VCLibs, version=14.0"
+    SupportsMultipleVersions="Error"
+    SupportedArchitectures="x86;x64;ARM">
+  <File Reference="Telegram.Td.winmd" Implementation="Telegram.Td.dll" />
+</FileList>
diff --git a/libs/tdlib/td/example/uwp/[Content_Types].xml b/libs/tdlib/td/example/uwp/[Content_Types].xml
new file mode 100644
index 0000000000..b91d46fa3c
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/[Content_Types].xml
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types">
+  <Default Extension="winmd" ContentType="application/octet-stream" />
+  <Default Extension="pri" ContentType="application/octet-stream" />
+  <Default Extension="dll" ContentType="application/octet-stream" />
+  <Default Extension="h" ContentType="application/octet-stream" />
+  <Default Extension="lib" ContentType="application/octet-stream" />
+  <Default Extension="pdb" ContentType="application/octet-stream" />
+  <Default Extension="png" ContentType="application/octet-stream" />
+  <Default Extension="props" ContentType="application/octet-stream" />
+  <Default Extension="txt" ContentType="text/plain" />
+  <Default Extension="vsixmanifest" ContentType="text/xml" />
+  <Default Extension="xml" ContentType="text/xml" />
+</Types>
diff --git a/libs/tdlib/td/example/uwp/app/.gitignore b/libs/tdlib/td/example/uwp/app/.gitignore
new file mode 100644
index 0000000000..37ab08165b
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/.gitignore
@@ -0,0 +1,5 @@
+.vs/
+bin/
+obj/
+project.lock.json
+TdApp.csproj.user
diff --git a/libs/tdlib/td/example/uwp/app/App.xaml b/libs/tdlib/td/example/uwp/app/App.xaml
new file mode 100644
index 0000000000..b4256fd441
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/App.xaml
@@ -0,0 +1,7 @@
+<Application
+    x:Class="TdApp.App"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:local="using:TdApp"
+    RequestedTheme="Light">
+</Application>
diff --git a/libs/tdlib/td/example/uwp/app/App.xaml.cs b/libs/tdlib/td/example/uwp/app/App.xaml.cs
new file mode 100644
index 0000000000..0ed0f96812
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/App.xaml.cs
@@ -0,0 +1,104 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+using System;
+using Windows.ApplicationModel;
+using Windows.ApplicationModel.Activation;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Navigation;
+
+namespace TdApp
+{
+    /// <summary>
+    /// Provides application-specific behavior to supplement the default Application class.
+    /// </summary>
+    sealed partial class App : Application
+    {
+        /// <summary>
+        /// Initializes the singleton application object.  This is the first line of authored code
+        /// executed, and as such is the logical equivalent of main() or WinMain().
+        /// </summary>
+        public App()
+        {
+            Microsoft.ApplicationInsights.WindowsAppInitializer.InitializeAsync(
+                Microsoft.ApplicationInsights.WindowsCollectors.Metadata |
+                Microsoft.ApplicationInsights.WindowsCollectors.Session);
+            this.InitializeComponent();
+            this.Suspending += OnSuspending;
+        }
+
+        /// <summary>
+        /// Invoked when the application is launched normally by the end user.  Other entry points
+        /// will be used such as when the application is launched to open a specific file.
+        /// </summary>
+        /// <param name="e">Details about the launch request and process.</param>
+        protected override void OnLaunched(LaunchActivatedEventArgs e)
+        {
+
+#if DEBUG
+            if (System.Diagnostics.Debugger.IsAttached)
+            {
+                this.DebugSettings.EnableFrameRateCounter = true;
+            }
+#endif
+
+            Frame rootFrame = Window.Current.Content as Frame;
+
+            // Do not repeat app initialization when the Window already has content,
+            // just ensure that the window is active
+            if (rootFrame == null)
+            {
+                // Create a Frame to act as the navigation context and navigate to the first page
+                rootFrame = new Frame();
+
+                rootFrame.NavigationFailed += OnNavigationFailed;
+
+                if (e.PreviousExecutionState == ApplicationExecutionState.Terminated)
+                {
+                    //TODO: Load state from previously suspended application
+                }
+
+                // Place the frame in the current Window
+                Window.Current.Content = rootFrame;
+            }
+
+            if (rootFrame.Content == null)
+            {
+                // When the navigation stack isn't restored navigate to the first page,
+                // configuring the new page by passing required information as a navigation
+                // parameter
+                rootFrame.Navigate(typeof(MainPage), e.Arguments);
+            }
+            // Ensure the current window is active
+            Window.Current.Activate();
+        }
+
+        /// <summary>
+        /// Invoked when Navigation to a certain page fails
+        /// </summary>
+        /// <param name="sender">The Frame which failed navigation</param>
+        /// <param name="e">Details about the navigation failure</param>
+        void OnNavigationFailed(object sender, NavigationFailedEventArgs e)
+        {
+            throw new Exception("Failed to load Page " + e.SourcePageType.FullName);
+        }
+
+        /// <summary>
+        /// Invoked when application execution is being suspended.  Application state is saved
+        /// without knowing whether the application will be terminated or resumed with the contents
+        /// of memory still intact.
+        /// </summary>
+        /// <param name="sender">The source of the suspend request.</param>
+        /// <param name="e">Details about the suspend request.</param>
+        private void OnSuspending(object sender, SuspendingEventArgs e)
+        {
+            var deferral = e.SuspendingOperation.GetDeferral();
+            //TODO: Save application state and stop any background activity
+            deferral.Complete();
+        }
+    }
+}
diff --git a/libs/tdlib/td/example/uwp/app/ApplicationInsights.config b/libs/tdlib/td/example/uwp/app/ApplicationInsights.config
new file mode 100644
index 0000000000..cb2a232da3
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/ApplicationInsights.config
@@ -0,0 +1,3 @@
+<?xml version="1.0" encoding="utf-8"?>
+<ApplicationInsights xmlns = "http://schemas.microsoft.com/ApplicationInsights/2013/Settings">
+</ApplicationInsights>
diff --git a/libs/tdlib/td/example/uwp/app/Assets/LockScreenLogo.scale-200.png b/libs/tdlib/td/example/uwp/app/Assets/LockScreenLogo.scale-200.png
new file mode 100644
index 0000000000..735f57adb5
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/Assets/LockScreenLogo.scale-200.png
diff --git a/libs/tdlib/td/example/uwp/app/Assets/SplashScreen.scale-200.png b/libs/tdlib/td/example/uwp/app/Assets/SplashScreen.scale-200.png
new file mode 100644
index 0000000000..023e7f1fed
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/Assets/SplashScreen.scale-200.png
diff --git a/libs/tdlib/td/example/uwp/app/Assets/Square150x150Logo.scale-200.png b/libs/tdlib/td/example/uwp/app/Assets/Square150x150Logo.scale-200.png
new file mode 100644
index 0000000000..af49fec1a5
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/Assets/Square150x150Logo.scale-200.png
diff --git a/libs/tdlib/td/example/uwp/app/Assets/Square44x44Logo.scale-200.png b/libs/tdlib/td/example/uwp/app/Assets/Square44x44Logo.scale-200.png
new file mode 100644
index 0000000000..ce342a2ec8
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/Assets/Square44x44Logo.scale-200.png
diff --git a/libs/tdlib/td/example/uwp/app/Assets/Square44x44Logo.targetsize-24_altform-unplated.png b/libs/tdlib/td/example/uwp/app/Assets/Square44x44Logo.targetsize-24_altform-unplated.png
new file mode 100644
index 0000000000..f6c02ce97e
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/Assets/Square44x44Logo.targetsize-24_altform-unplated.png
diff --git a/libs/tdlib/td/example/uwp/app/Assets/StoreLogo.png b/libs/tdlib/td/example/uwp/app/Assets/StoreLogo.png
new file mode 100644
index 0000000000..7385b56c0e
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/Assets/StoreLogo.png
diff --git a/libs/tdlib/td/example/uwp/app/Assets/Wide310x150Logo.scale-200.png b/libs/tdlib/td/example/uwp/app/Assets/Wide310x150Logo.scale-200.png
new file mode 100644
index 0000000000..288995b397
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/Assets/Wide310x150Logo.scale-200.png
diff --git a/libs/tdlib/td/example/uwp/app/MainPage.xaml b/libs/tdlib/td/example/uwp/app/MainPage.xaml
new file mode 100644
index 0000000000..cdff97d9f3
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/MainPage.xaml
@@ -0,0 +1,29 @@
+<Page
+    x:Class="TdApp.MainPage"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:local="using:TdApp"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    mc:Ignorable="d"
+    x:Name="Self">
+
+    <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
+        <Grid.RowDefinitions>
+            <RowDefinition Height="Auto"/>
+            <RowDefinition Height="*"/>
+        </Grid.RowDefinitions>
+        <Grid>
+            <Grid.ColumnDefinitions>
+                <ColumnDefinition Width="*"/>
+                <ColumnDefinition Width="Auto"/>
+            </Grid.ColumnDefinitions>
+            <TextBox x:Name="Input"/>
+            <Button Grid.Column="1" x:Name="Send" Content="send" Click="Button_Click"/>
+        </Grid>
+        <ListBox Grid.Row="1" x:Name="ItemsControl" ItemsSource="{Binding Items, ElementName=Self}">
+
+        </ListBox>
+        <!--<Button Content="Test" Click="Button_Click"/>-->
+    </Grid>
+</Page>
diff --git a/libs/tdlib/td/example/uwp/app/MainPage.xaml.cs b/libs/tdlib/td/example/uwp/app/MainPage.xaml.cs
new file mode 100644
index 0000000000..9bdf5070ee
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/MainPage.xaml.cs
@@ -0,0 +1,171 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+using System;
+using System.IO;
+using Td = Telegram.Td;
+using TdApi = Telegram.Td.Api;
+using Windows.UI.Core;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+
+namespace TdApp
+{
+    public sealed partial class MainPage : Page
+    {
+        public System.Collections.ObjectModel.ObservableCollection<string> Items { get; set; }
+
+        private static MyClientResultHandler _handler;
+
+        public MainPage()
+        {
+            InitializeComponent();
+
+            Items = new System.Collections.ObjectModel.ObservableCollection<string>();
+            _handler = new MyClientResultHandler(this);
+
+            System.Threading.Tasks.Task.Run(() =>
+            {
+                try
+                {
+                    Td.Log.SetFilePath(Path.Combine(Windows.Storage.ApplicationData.Current.LocalFolder.Path, "log"));
+                    _client = Td.Client.Create(_handler);
+                    var parameters = new TdApi.TdlibParameters();
+                    parameters.DatabaseDirectory = Windows.Storage.ApplicationData.Current.LocalFolder.Path;
+                    parameters.UseSecretChats = true;
+                    parameters.UseMessageDatabase = true;
+                    parameters.ApiId = 94575;
+                    parameters.ApiHash = "a3406de8d171bb422bb6ddf3bbd800e2";
+                    parameters.SystemLanguageCode = "en";
+                    parameters.DeviceModel = "en";
+                    parameters.SystemVersion = "en";
+                    parameters.ApplicationVersion = "1.0.0";
+                    _client.Send(new TdApi.SetTdlibParameters(parameters), null);
+                    _client.Send(new TdApi.CheckDatabaseEncryptionKey(), null);
+                    _client.Run();
+                }
+                catch (Exception ex)
+                {
+                    Print(ex.ToString());
+                }
+            });
+        }
+
+        public void Print(String str)
+        {
+            var delayTask = Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
+            {
+                Items.Insert(0, str.Substring(0, Math.Min(1024, str.Length)));
+            });
+        }
+
+        private static Td.Client _client;
+
+        private void AcceptCommand(String command)
+        {
+            Input.Text = string.Empty;
+            Items.Insert(0, string.Format(">>{0}", command));
+        }
+        private void Button_Click(object sender, RoutedEventArgs e)
+        {
+            var command = Input.Text;
+
+            if (command.StartsWith("DESTROY"))
+            {
+                AcceptCommand("Destroy");
+                _client.Send(new TdApi.Destroy(), _handler);
+            }
+            else if (command.StartsWith("lo"))
+            {
+                AcceptCommand("LogOut");
+                _client.Send(new TdApi.LogOut(), _handler);
+            }
+            else if (command.StartsWith("gas"))
+            {
+                AcceptCommand(command);
+                _client.Send(new TdApi.GetAuthorizationState(), _handler);
+            }
+            else if (command.StartsWith("sap"))
+            {
+                var args = command.Split(" ".ToCharArray(), 2);
+                AcceptCommand(command);
+                _client.Send(new TdApi.SetAuthenticationPhoneNumber(args[1], false, false), _handler);
+            }
+            else if (command.StartsWith("cac"))
+            {
+                var args = command.Split(" ".ToCharArray(), 2);
+                AcceptCommand(command);
+                _client.Send(new TdApi.CheckAuthenticationCode(args[1], String.Empty, String.Empty), _handler);
+            }
+            else if (command.StartsWith("cap"))
+            {
+                var args = command.Split(" ".ToCharArray(), 2);
+                AcceptCommand(command);
+                _client.Send(new TdApi.CheckAuthenticationPassword(args[1]), _handler);
+            }
+            else if (command.StartsWith("gco"))
+            {
+                var args = command.Split(" ".ToCharArray(), 2);
+                AcceptCommand(command);
+                _client.Send(new TdApi.SearchContacts(), _handler);
+            }
+            else if (command.StartsWith("df"))
+            {
+                var args = command.Split(" ".ToCharArray(), 2);
+                AcceptCommand(command);
+                _client.Send(new TdApi.DownloadFile(Int32.Parse(args[1]), 1), _handler);
+            }
+            else if (command.StartsWith("bench"))
+            {
+                var args = command.Split(" ".ToCharArray(), 2);
+                AcceptCommand(command);
+                var cnt = Int32.Parse(args[1]);
+                var handler = new BenchSimpleHandler(this, cnt);
+                for (int i = 0; i < cnt; i++)
+                {
+                    _client.Send(new TdApi.TestSquareInt(123), handler);
+                }
+            }
+        }
+    }
+
+    class MyClientResultHandler : Td.ClientResultHandler
+    {
+        private MainPage _page;
+
+        public MyClientResultHandler(MainPage page)
+        {
+            _page = page;
+        }
+
+        public void OnResult(TdApi.BaseObject obj)
+        {
+            var str = obj.ToString();
+            _page.Print(str);
+        }
+    }
+
+    class BenchSimpleHandler : Td.ClientResultHandler
+    {
+        private MainPage _page;
+        private int _cnt;
+
+        public BenchSimpleHandler(MainPage page, int cnt)
+        {
+            _page = page;
+            _cnt = cnt;
+        }
+
+        public void OnResult(TdApi.BaseObject obj)
+        {
+            _cnt--;
+            if (_cnt == 0)
+            {
+                _page.Print("DONE");
+            }
+        }
+    }
+}
diff --git a/libs/tdlib/td/example/uwp/app/Package.appxmanifest b/libs/tdlib/td/example/uwp/app/Package.appxmanifest
new file mode 100644
index 0000000000..ca1235ffa7
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/Package.appxmanifest
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Package xmlns="http://schemas.microsoft.com/appx/manifest/foundation/windows10" xmlns:mp="http://schemas.microsoft.com/appx/2014/phone/manifest" xmlns:uap="http://schemas.microsoft.com/appx/manifest/uap/windows10" IgnorableNamespaces="uap mp">
+  <Identity Name="1c9ba6de-23cf-4aef-803b-91fcc451b69a" Publisher="CN=arseny30" Version="1.0.0.0" />
+  <mp:PhoneIdentity PhoneProductId="1c9ba6de-23cf-4aef-803b-91fcc451b69a" PhonePublisherId="00000000-0000-0000-0000-000000000000" />
+  <Properties>
+    <DisplayName>TdApp</DisplayName>
+    <PublisherDisplayName>arseny30</PublisherDisplayName>
+    <Logo>Assets\StoreLogo.png</Logo>
+  </Properties>
+  <Dependencies>
+    <TargetDeviceFamily Name="Windows.Universal" MinVersion="10.0.0.0" MaxVersionTested="10.0.0.0" />
+  </Dependencies>
+  <Resources>
+    <Resource Language="x-generate" />
+  </Resources>
+  <Applications>
+    <Application Id="App" Executable="$targetnametoken$.exe" EntryPoint="TdApp.App">
+      <uap:VisualElements DisplayName="TdApp" Square150x150Logo="Assets\Square150x150Logo.png" Square44x44Logo="Assets\Square44x44Logo.png" Description="TdApp" BackgroundColor="transparent">
+        <uap:DefaultTile Wide310x150Logo="Assets\Wide310x150Logo.png">
+        </uap:DefaultTile>
+        <uap:SplashScreen Image="Assets\SplashScreen.png" />
+      </uap:VisualElements>
+    </Application>
+  </Applications>
+  <Capabilities>
+    <Capability Name="internetClient" />
+  </Capabilities>
+</Package>
\ No newline at end of file
diff --git a/libs/tdlib/td/example/uwp/app/Properties/AssemblyInfo.cs b/libs/tdlib/td/example/uwp/app/Properties/AssemblyInfo.cs
new file mode 100644
index 0000000000..99e2b83bea
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/Properties/AssemblyInfo.cs
@@ -0,0 +1,29 @@
+using System.Reflection;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+// General Information about an assembly is controlled through the following
+// set of attributes. Change these attribute values to modify the information
+// associated with an assembly.
+[assembly: AssemblyTitle("App2")]
+[assembly: AssemblyDescription("")]
+[assembly: AssemblyConfiguration("")]
+[assembly: AssemblyCompany("")]
+[assembly: AssemblyProduct("App2")]
+[assembly: AssemblyCopyright("Copyright © 2015-2018")]
+[assembly: AssemblyTrademark("")]
+[assembly: AssemblyCulture("")]
+
+// Version information for an assembly consists of the following four values:
+//
+//      Major Version
+//      Minor Version
+//      Build Number
+//      Revision
+//
+// You can specify all the values or you can default the Build and Revision Numbers
+// by using the '*' as shown below:
+// [assembly: AssemblyVersion("1.0.*")]
+[assembly: AssemblyVersion("1.0.0.0")]
+[assembly: AssemblyFileVersion("1.0.0.0")]
+[assembly: ComVisible(false)]
\ No newline at end of file
diff --git a/libs/tdlib/td/example/uwp/app/Properties/Default.rd.xml b/libs/tdlib/td/example/uwp/app/Properties/Default.rd.xml
new file mode 100644
index 0000000000..479eb7669d
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/Properties/Default.rd.xml
@@ -0,0 +1,31 @@
+<!--
+    This file contains Runtime Directives used by .NET Native. The defaults here are suitable for most
+    developers. However, you can modify these parameters to modify the behavior of the .NET Native
+    optimizer.
+
+    Runtime Directives are documented at http://go.microsoft.com/fwlink/?LinkID=391919
+
+    To fully enable reflection for App1.MyClass and all of its public/private members
+    <Type Name="App1.MyClass" Dynamic="Required All"/>
+
+    To enable dynamic creation of the specific instantiation of AppClass<T> over System.Int32
+    <TypeInstantiation Name="App1.AppClass" Arguments="System.Int32" Activate="Required Public" />
+
+    Using the Namespace directive to apply reflection policy to all the types in a particular namespace
+    <Namespace Name="DataClasses.ViewModels" Seralize="All" />
+-->
+
+<Directives xmlns="http://schemas.microsoft.com/netfx/2013/01/metadata">
+  <Application>
+    <!--
+      An Assembly element with Name="*Application*" applies to all assemblies in
+      the application package. The asterisks are not wildcards.
+    -->
+    <Assembly Name="*Application*" Dynamic="Required All" />
+
+
+    <!-- Add your application specific runtime directives here. -->
+
+
+  </Application>
+</Directives>
\ No newline at end of file
diff --git a/libs/tdlib/td/example/uwp/app/TdApp.csproj b/libs/tdlib/td/example/uwp/app/TdApp.csproj
new file mode 100644
index 0000000000..b3d1d944d1
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/TdApp.csproj
@@ -0,0 +1,151 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="14.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">x86</Platform>
+    <ProjectGuid>{0B971A4C-EC00-4FED-BCC2-FCD03B78D644}</ProjectGuid>
+    <OutputType>AppContainerExe</OutputType>
+    <AppDesignerFolder>Properties</AppDesignerFolder>
+    <RootNamespace>TdApp</RootNamespace>
+    <AssemblyName>TdApp</AssemblyName>
+    <DefaultLanguage>en-US</DefaultLanguage>
+    <TargetPlatformIdentifier>UAP</TargetPlatformIdentifier>
+    <TargetPlatformVersion>10.0.10586.0</TargetPlatformVersion>
+    <TargetPlatformMinVersion>10.0.10240.0</TargetPlatformMinVersion>
+    <MinimumVisualStudioVersion>14</MinimumVisualStudioVersion>
+    <FileAlignment>512</FileAlignment>
+    <ProjectTypeGuids>{A5A43C5B-DE2A-4C0C-9213-0A381AF9435A};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+    <PackageCertificateKeyFile>TdApp_TemporaryKey.pfx</PackageCertificateKeyFile>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|x86'">
+    <DebugSymbols>true</DebugSymbols>
+    <OutputPath>bin\x86\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
+    <NoWarn>;2008</NoWarn>
+    <DebugType>full</DebugType>
+    <PlatformTarget>x86</PlatformTarget>
+    <UseVSHostingProcess>false</UseVSHostingProcess>
+    <ErrorReport>prompt</ErrorReport>
+    <Prefer32Bit>true</Prefer32Bit>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x86'">
+    <OutputPath>bin\x86\Release\</OutputPath>
+    <DefineConstants>TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
+    <Optimize>true</Optimize>
+    <NoWarn>;2008</NoWarn>
+    <DebugType>pdbonly</DebugType>
+    <PlatformTarget>x86</PlatformTarget>
+    <UseVSHostingProcess>false</UseVSHostingProcess>
+    <ErrorReport>prompt</ErrorReport>
+    <Prefer32Bit>true</Prefer32Bit>
+    <UseDotNetNativeToolchain>true</UseDotNetNativeToolchain>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|ARM'">
+    <DebugSymbols>true</DebugSymbols>
+    <OutputPath>bin\ARM\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
+    <NoWarn>;2008</NoWarn>
+    <DebugType>full</DebugType>
+    <PlatformTarget>ARM</PlatformTarget>
+    <UseVSHostingProcess>false</UseVSHostingProcess>
+    <ErrorReport>prompt</ErrorReport>
+    <Prefer32Bit>true</Prefer32Bit>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|ARM'">
+    <OutputPath>bin\ARM\Release\</OutputPath>
+    <DefineConstants>TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
+    <Optimize>true</Optimize>
+    <NoWarn>;2008</NoWarn>
+    <DebugType>pdbonly</DebugType>
+    <PlatformTarget>ARM</PlatformTarget>
+    <UseVSHostingProcess>false</UseVSHostingProcess>
+    <ErrorReport>prompt</ErrorReport>
+    <Prefer32Bit>true</Prefer32Bit>
+    <UseDotNetNativeToolchain>true</UseDotNetNativeToolchain>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|x64'">
+    <DebugSymbols>true</DebugSymbols>
+    <OutputPath>bin\x64\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
+    <NoWarn>;2008</NoWarn>
+    <DebugType>full</DebugType>
+    <PlatformTarget>x64</PlatformTarget>
+    <UseVSHostingProcess>false</UseVSHostingProcess>
+    <ErrorReport>prompt</ErrorReport>
+    <Prefer32Bit>true</Prefer32Bit>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x64'">
+    <OutputPath>bin\x64\Release\</OutputPath>
+    <DefineConstants>TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
+    <Optimize>true</Optimize>
+    <NoWarn>;2008</NoWarn>
+    <DebugType>pdbonly</DebugType>
+    <PlatformTarget>x64</PlatformTarget>
+    <UseVSHostingProcess>false</UseVSHostingProcess>
+    <ErrorReport>prompt</ErrorReport>
+    <Prefer32Bit>true</Prefer32Bit>
+    <UseDotNetNativeToolchain>true</UseDotNetNativeToolchain>
+  </PropertyGroup>
+  <ItemGroup>
+    <!-- A reference to the entire .Net Framework and Windows SDK are automatically included -->
+    <Content Include="ApplicationInsights.config">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <None Include="project.json" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="App.xaml.cs">
+      <DependentUpon>App.xaml</DependentUpon>
+    </Compile>
+    <Compile Include="MainPage.xaml.cs">
+      <DependentUpon>MainPage.xaml</DependentUpon>
+    </Compile>
+    <Compile Include="Properties\AssemblyInfo.cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <AppxManifest Include="Package.appxmanifest">
+      <SubType>Designer</SubType>
+    </AppxManifest>
+    <None Include="TdApp_TemporaryKey.pfx" />
+  </ItemGroup>
+  <ItemGroup>
+    <Content Include="Properties\Default.rd.xml" />
+    <Content Include="Assets\LockScreenLogo.scale-200.png" />
+    <Content Include="Assets\SplashScreen.scale-200.png" />
+    <Content Include="Assets\Square150x150Logo.scale-200.png" />
+    <Content Include="Assets\Square44x44Logo.scale-200.png" />
+    <Content Include="Assets\Square44x44Logo.targetsize-24_altform-unplated.png" />
+    <Content Include="Assets\StoreLogo.png" />
+    <Content Include="Assets\Wide310x150Logo.scale-200.png" />
+  </ItemGroup>
+  <ItemGroup>
+    <ApplicationDefinition Include="App.xaml">
+      <Generator>MSBuild:Compile</Generator>
+      <SubType>Designer</SubType>
+    </ApplicationDefinition>
+    <Page Include="MainPage.xaml">
+      <Generator>MSBuild:Compile</Generator>
+      <SubType>Designer</SubType>
+    </Page>
+  </ItemGroup>
+  <ItemGroup>
+    <SDKReference Include="Microsoft.VCLibs, Version=14.0">
+      <Name>Visual C++ 2015 Runtime for Universal Windows Platform Apps</Name>
+    </SDKReference>
+    <SDKReference Include="Telegram.Td.UWP, Version=1.0">
+      <Name>TDLib for Universal Windows Platform</Name>
+    </SDKReference>
+  </ItemGroup>
+  <PropertyGroup Condition=" '$(VisualStudioVersion)' == '' or '$(VisualStudioVersion)' &lt; '14.0' ">
+    <VisualStudioVersion>14.0</VisualStudioVersion>
+  </PropertyGroup>
+  <Import Project="$(MSBuildExtensionsPath)\Microsoft\WindowsXaml\v$(VisualStudioVersion)\Microsoft.Windows.UI.Xaml.CSharp.targets" />
+  <!-- To modify your build process, add your task inside one of the targets below and uncomment it.
+       Other similar extension points exist, see Microsoft.Common.targets.
+  <Target Name="BeforeBuild">
+  </Target>
+  <Target Name="AfterBuild">
+  </Target>
+  -->
+</Project>
\ No newline at end of file
diff --git a/libs/tdlib/td/example/uwp/app/TdApp_TemporaryKey.pfx b/libs/tdlib/td/example/uwp/app/TdApp_TemporaryKey.pfx
new file mode 100644
index 0000000000..05ffbcabbc
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/TdApp_TemporaryKey.pfx
diff --git a/libs/tdlib/td/example/uwp/app/project.json b/libs/tdlib/td/example/uwp/app/project.json
new file mode 100644
index 0000000000..e3b2dba25f
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/app/project.json
@@ -0,0 +1,19 @@
+{
+  "dependencies": {
+    "Microsoft.ApplicationInsights": "1.0.0",
+    "Microsoft.ApplicationInsights.PersistenceChannel": "1.0.0",
+    "Microsoft.ApplicationInsights.WindowsApps": "1.0.0",
+    "Microsoft.NETCore.UniversalWindowsPlatform": "5.0.0"
+  },
+  "frameworks": {
+    "uap10.0": {}
+  },
+  "runtimes": {
+    "win10-arm": {},
+    "win10-arm-aot": {},
+    "win10-x86": {},
+    "win10-x86-aot": {},
+    "win10-x64": {},
+    "win10-x64-aot": {}
+  }
+}
\ No newline at end of file
diff --git a/libs/tdlib/td/example/uwp/build.ps1 b/libs/tdlib/td/example/uwp/build.ps1
new file mode 100644
index 0000000000..71156b0a2d
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/build.ps1
@@ -0,0 +1,142 @@
+param (
+  [string]$vcpkg_root = $(throw "-vcpkg_root=<path to vcpkg> is required"),
+  [string]$arch = "",
+  [string]$mode = "all",
+  [string]$compress = "7z"
+)
+$ErrorActionPreference = "Stop"
+
+$vcpkg_root = Resolve-Path $vcpkg_root
+
+$vcpkg_cmake="${vcpkg_root}\scripts\buildsystems\vcpkg.cmake"
+$arch_list = @( "x86", "x64", "arm" )
+if ($arch) {
+  $arch_list = @(, $arch)
+}
+
+$td_root = Resolve-Path "../.."
+
+function CheckLastExitCode {
+  if ($LastExitCode -ne 0) {
+    $msg = @"
+EXE RETURNED EXIT CODE $LastExitCode
+CALLSTACK:$(Get-PSCallStack | Out-String)
+"@
+    throw $msg
+  }
+}
+
+function clean {
+  Remove-Item build-* -Force -Recurse -ErrorAction SilentlyContinue
+}
+
+function prepare {
+  New-Item -ItemType Directory -Force -Path build-native
+
+  cd build-native
+
+  cmake $td_root -DCMAKE_TOOLCHAIN_FILE="$vcpkg_cmake" -DTD_ENABLE_DOTNET=1
+  CheckLastExitCode
+  cmake --build . --target prepare_cross_compiling
+  CheckLastExitCode
+
+  cd ..
+}
+
+function config {
+  New-Item -ItemType Directory -Force -Path build-uwp
+  cd build-uwp
+
+  ForEach($arch in $arch_list) {
+    echo "Config Arch = [$arch]"
+    New-Item -ItemType Directory -Force -Path $arch
+    cd $arch
+    echo "${td_root}"
+    $fixed_arch = $arch
+    if ($arch -eq "x86") {
+      $fixed_arch = "win32"
+    }
+    cmake "$td_root" -A $fixed_arch -DCMAKE_SYSTEM_VERSION="10.0" -DCMAKE_SYSTEM_NAME="WindowsStore" -DCMAKE_TOOLCHAIN_FILE="$vcpkg_cmake" -DTD_ENABLE_DOTNET=1
+    CheckLastExitCode
+    cd ..
+  }
+  echo "done"
+  cd ..
+}
+
+function build {
+  cd build-uwp
+  ForEach($arch in $arch_list) {
+    echo "Build Arch = [$arch]"
+    cd $arch
+    cmake --build . --config Release --target tddotnet
+    cmake --build . --config Debug --target tddotnet
+    cd ..
+  }
+  cd ..
+}
+
+function export {
+  cd build-uwp
+  Remove-Item vsix -Force -Recurse -ErrorAction SilentlyContinue
+  New-Item -ItemType Directory -Force -Path vsix
+  cp ../SDKManifest.xml vsix
+  cp ../extension.vsixmanifest vsix
+  cp '../`[Content_Types`].xml' vsix
+  cp ../LICENSE_1_0.txt vsix
+
+  ForEach($arch in $arch_list) {
+    New-Item -ItemType Directory -Force -Path vsix/DesignTime/Debug/${arch}
+    New-Item -ItemType Directory -Force -Path vsix/DesignTime/Retail/${arch}
+    New-Item -ItemType Directory -Force -Path vsix/Redist/Debug/${arch}
+    New-Item -ItemType Directory -Force -Path vsix/Redist/Retail/${arch}
+    New-Item -ItemType Directory -Force -Path vsix/References/CommonConfiguration/${arch}
+
+    cp ${arch}/Debug/* -include "LIBEAY*","SSLEAY*","zlib*" vsix/Redist/Debug/${arch}/
+    cp ${arch}/Release/* -include "LIBEAY*","SSLEAY*","zlib*" vsix/Redist/Retail/${arch}/
+
+    cp ${arch}/Debug/* -filter "Telegram.Td.*" -include "*.lib" vsix/DesignTime/Debug/${arch}/
+    cp ${arch}/Release/*  -filter "Telegram.Td.*" -include "*.lib" vsix/DesignTime/Retail/${arch}/
+
+    cp ${arch}/Debug/*  -filter "Telegram.Td.*" -include "*.pdb","*.dll" vsix/Redist/Debug/${arch}/
+    cp ${arch}/Release/*  -filter "Telegram.Td.*" -include "*.pdb","*.dll" vsix/Redist/Retail/${arch}/
+
+    cp ${arch}/Release/* -filter "Telegram.Td.*" -include "*.pri","*.winmd","*.xml" vsix/References/CommonConfiguration/${arch}/
+  }
+
+  cd vsix
+
+  if ($compress -eq "zip") {
+    zip -r tdlib.vsix *
+  } elseif ($compress -eq "winrar") {
+    WinRAR.exe a -afzip -r -ep1 tdlib.vsix *
+  } else {
+    7z.exe a -tzip -r tdlib.vsix *
+  }
+  cd ..
+}
+
+function run {
+  Push-Location
+  Try {
+    if ($mode -eq "clean") {
+      clean
+    }
+    if (($mode -eq "prepare") -or ($mode -eq "all")) {
+      prepare
+    }
+    if (($mode -eq "config") -or ( $mode -eq "all")) {
+      config
+    }
+    if (($mode -eq "build") -or ($mode -eq "all")) {
+      build
+    }
+    if (($mode -eq "export") -or ($mode -eq "all")) {
+      export
+    }
+  } Finally {
+    Pop-Location
+  }
+}
+
+run
diff --git a/libs/tdlib/td/example/uwp/extension.vsixmanifest b/libs/tdlib/td/example/uwp/extension.vsixmanifest
new file mode 100644
index 0000000000..cfcfdb57af
--- /dev/null
+++ b/libs/tdlib/td/example/uwp/extension.vsixmanifest
@@ -0,0 +1,17 @@
+<PackageManifest Version="2.0.0" xmlns="http://schemas.microsoft.com/developer/vsx-schema/2011">
+  <Metadata>
+    <Identity Id="Telegram.Td.UWP" Version="1.2.0" Language="en-US" Publisher="Telegram LLC" />
+    <DisplayName>TDLib for Universal Windows Platform</DisplayName>
+    <Description>TDLib is a library for building Telegram clients</Description>
+    <MoreInfo>https://core.telegram.org/tdlib</MoreInfo>
+    <Tags>Telegram, TDLib, library, client, API</Tags>
+    <License>LICENSE_1_0.txt</License>
+    <ReleaseNotes>https://github.com/tdlib/td/blob/master/CHANGELOG.md</ReleaseNotes>
+  </Metadata>
+  <Installation Scope="Global">
+    <InstallationTarget Id="Microsoft.ExtensionSDK" TargetPlatformIdentifier="UAP" TargetPlatformVersion="v0.8.0.0" SdkName="Telegram.Td.UWP" SdkVersion="1.0" />
+  </Installation>
+  <Assets>
+    <Asset Type="Microsoft.ExtensionSDK" Path="SDKManifest.xml" />
+  </Assets>
+</PackageManifest>
diff --git a/libs/tdlib/td/format.ps1 b/libs/tdlib/td/format.ps1
new file mode 100644
index 0000000000..f64296cc36
--- /dev/null
+++ b/libs/tdlib/td/format.ps1
@@ -0,0 +1,3 @@
+./src.ps1 | Select-String -NotMatch "CxCli.h" | Select-String -NotMatch "dotnet" | ForEach-Object {
+  clang-format -verbose -style=file -i $_
+}
diff --git a/libs/tdlib/td/format.sh b/libs/tdlib/td/format.sh
new file mode 100644
index 0000000000..64280e3384
--- /dev/null
+++ b/libs/tdlib/td/format.sh
@@ -0,0 +1,2 @@
+#!/bin/sh
+./src.sh | grep -v CxCli.h | grep -iv dotnet | xargs -n 1 clang-format -verbose -style=file -i
diff --git a/libs/tdlib/td/gen_git_commit_h.ps1 b/libs/tdlib/td/gen_git_commit_h.ps1
new file mode 100644
index 0000000000..2893f89c2a
--- /dev/null
+++ b/libs/tdlib/td/gen_git_commit_h.ps1
@@ -0,0 +1,9 @@
+$commit = git rev-parse HEAD
+git diff-index --quiet HEAD
+$dirty = $LASTEXITCODE
+echo "#pragma once`r`n#define GIT_COMMIT `"$commit`"`r`n#define GIT_DIRTY $dirty" | out-file -encoding ASCII auto/git_info.h.new
+if (-not (Test-Path .\auto\git_info.h) -or (Compare-Object $(Get-Content .\auto\git_info.h.new) $(Get-Content .\auto\git_info.h))) {
+  mv -Force auto/git_info.h.new auto/git_info.h
+} else {
+  rm auto/git_info.h.new
+}
diff --git a/libs/tdlib/td/gen_git_commit_h.sh b/libs/tdlib/td/gen_git_commit_h.sh
new file mode 100644
index 0000000000..b3416b2983
--- /dev/null
+++ b/libs/tdlib/td/gen_git_commit_h.sh
@@ -0,0 +1,11 @@
+#!/bin/sh
+commit=$(git rev-parse HEAD)
+git diff-index --quiet HEAD
+dirty=$?
+printf "#pragma once\n#define GIT_COMMIT \"$commit\"\n#define GIT_DIRTY $dirty\n" > auto/git_info.h.new
+if cmp -s auto/git_info.h.new auto/git_info.h 2>&1 > /dev/null
+then
+  rm -f auto/git_info.h.new
+else
+  mv -f auto/git_info.h.new auto/git_info.h
+fi
diff --git a/libs/tdlib/td/memprof/memprof.cpp b/libs/tdlib/td/memprof/memprof.cpp
new file mode 100644
index 0000000000..11822ee00a
--- /dev/null
+++ b/libs/tdlib/td/memprof/memprof.cpp
@@ -0,0 +1,317 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "memprof/memprof.h"
+
+#include "td/utils/port/platform.h"
+
+#if (TD_DARWIN || TD_LINUX) && defined(USE_MEMPROF)
+#include <algorithm>
+#include <atomic>
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+#include <functional>
+#include <new>
+#include <utility>
+#include <vector>
+
+#include <dlfcn.h>
+#include <execinfo.h>
+
+bool is_memprof_on() {
+  return true;
+}
+
+#if USE_MEMPROF_SAFE
+double get_fast_backtrace_success_rate() {
+  return 0;
+}
+#else
+
+#if TD_LINUX
+extern void *__libc_stack_end;
+#endif
+
+static void *get_bp() {
+  void *bp;
+#if defined(__i386__)
+  __asm__ volatile("movl %%ebp, %[r]" : [r] "=r"(bp));
+#elif defined(__x86_64__)
+  __asm__ volatile("movq %%rbp, %[r]" : [r] "=r"(bp));
+#endif
+  return bp;
+}
+
+static int fast_backtrace(void **buffer, int size) {
+  struct stack_frame {
+    stack_frame *bp;
+    void *ip;
+  };
+
+  stack_frame *bp = reinterpret_cast<stack_frame *>(get_bp());
+  int i = 0;
+  while (i < size &&
+#if TD_LINUX
+         static_cast<void *>(bp) <= __libc_stack_end &&
+#endif
+         !(reinterpret_cast<std::uintptr_t>(static_cast<void *>(bp)) & (sizeof(void *) - 1))) {
+    void *ip = bp->ip;
+    buffer[i++] = ip;
+    stack_frame *p = bp->bp;
+    if (p <= bp) {
+      break;
+    }
+    bp = p;
+  }
+  return i;
+}
+
+static std::atomic<std::size_t> fast_backtrace_failed_cnt, backtrace_total_cnt;
+double get_fast_backtrace_success_rate() {
+  return 1 - static_cast<double>(fast_backtrace_failed_cnt.load(std::memory_order_relaxed)) /
+                 static_cast<double>(std::max(std::size_t(1), backtrace_total_cnt.load(std::memory_order_relaxed)));
+}
+
+#endif
+
+static Backtrace get_backtrace() {
+  static __thread bool in_backtrace;  // static zero-initialized
+  Backtrace res{{nullptr}};
+  if (in_backtrace) {
+    return res;
+  }
+  in_backtrace = true;
+  std::array<void *, res.size() + BACKTRACE_SHIFT + 10> tmp{{nullptr}};
+  std::size_t n;
+#if USE_MEMPROF_SAFE
+  n = backtrace(tmp.data(), static_cast<int>(tmp.size()));
+#else
+  n = fast_backtrace(tmp.data(), static_cast<int>(tmp.size()));
+  auto from_shared = [](void *ptr) {
+    return reinterpret_cast<std::uintptr_t>(ptr) > static_cast<std::uintptr_t>(0x700000000000ull);
+  };
+
+#if !USE_MEMPROF_FAST
+  auto end = tmp.begin() + std::min(res.size() + BACKTRACE_SHIFT, n);
+  if (std::find_if(tmp.begin(), end, from_shared) != end) {
+    fast_backtrace_failed_cnt.fetch_add(1, std::memory_order_relaxed);
+    n = backtrace(tmp.data(), static_cast<int>(tmp.size()));
+  }
+  backtrace_total_cnt.fetch_add(1, std::memory_order_relaxed);
+#endif
+  n = std::remove_if(tmp.begin(), tmp.begin() + n, from_shared) - tmp.begin();
+#endif
+  n = std::min(res.size() + BACKTRACE_SHIFT, n);
+
+  for (std::size_t i = BACKTRACE_SHIFT; i < n; i++) {
+    res[i - BACKTRACE_SHIFT] = tmp[i];
+  }
+  in_backtrace = false;
+  return res;
+}
+
+static constexpr std::size_t reserved = 16;
+static constexpr std::int32_t malloc_info_magic = 0x27138373;
+struct malloc_info {
+  std::int32_t magic;
+  std::int32_t size;
+  std::int32_t ht_pos;
+};
+
+static std::uint64_t get_hash(const Backtrace &bt) {
+  std::uint64_t h = 7;
+  for (std::size_t i = 0; i < bt.size() && i < BACKTRACE_HASHED_LENGTH; i++) {
+    h = h * 0x4372897893428797lu + reinterpret_cast<std::uintptr_t>(bt[i]);
+  }
+  return h;
+}
+
+struct HashtableNode {
+  std::atomic<std::uint64_t> hash;
+  Backtrace backtrace;
+  std::atomic<std::size_t> size;
+};
+
+static constexpr std::size_t ht_max_size = 1000000;
+static std::atomic<std::size_t> ht_size{0};
+static std::array<HashtableNode, ht_max_size> ht;
+
+std::size_t get_ht_size() {
+  return ht_size.load();
+}
+
+std::int32_t get_ht_pos(const Backtrace &bt, bool force = false) {
+  auto hash = get_hash(bt);
+  std::int32_t pos = static_cast<std::int32_t>(hash % ht.size());
+  bool was_overflow = false;
+  while (true) {
+    auto pos_hash = ht[pos].hash.load();
+    if (pos_hash == 0) {
+      if (ht_size > ht_max_size / 2) {
+        if (force) {
+          assert(ht_size * 10 < ht_max_size * 7);
+        } else {
+          Backtrace unknown_bt{{nullptr}};
+          unknown_bt[0] = reinterpret_cast<void *>(1);
+          return get_ht_pos(unknown_bt, true);
+        }
+      }
+
+      std::uint64_t expected = 0;
+      if (ht[pos].hash.compare_exchange_strong(expected, hash)) {
+        ht[pos].backtrace = bt;
+        ++ht_size;
+        return pos;
+      }
+    } else if (pos_hash == hash) {
+      return pos;
+    } else {
+      pos++;
+      if (pos == static_cast<std::int32_t>(ht.size())) {
+        pos = 0;
+        if (was_overflow) {
+          // unreachable
+          std::abort();
+        }
+        was_overflow = true;
+      }
+    }
+  }
+}
+
+void dump_alloc(const std::function<void(const AllocInfo &)> &func) {
+  for (auto &node : ht) {
+    if (node.size == 0) {
+      continue;
+    }
+    func(AllocInfo{node.backtrace, node.size.load()});
+  }
+}
+
+void register_xalloc(malloc_info *info, std::int32_t diff) {
+  if (diff > 0) {
+    ht[info->ht_pos].size += info->size;
+  } else {
+    ht[info->ht_pos].size -= info->size;
+  }
+}
+
+extern "C" {
+
+static void *malloc_with_frame(std::size_t size, const Backtrace &frame) {
+  static_assert(reserved % alignof(std::max_align_t) == 0, "fail");
+  static_assert(reserved >= sizeof(malloc_info), "fail");
+#if TD_DARWIN
+  static void *malloc_void = dlsym(RTLD_NEXT, "malloc");
+  static auto malloc_old = *reinterpret_cast<decltype(malloc) **>(&malloc_void);
+#else
+  extern decltype(malloc) __libc_malloc;
+  static auto malloc_old = __libc_malloc;
+#endif
+  auto *info = static_cast<malloc_info *>(malloc_old(size + reserved));
+  auto *buf = reinterpret_cast<char *>(info);
+
+  info->magic = malloc_info_magic;
+  info->size = static_cast<std::int32_t>(size);
+  info->ht_pos = get_ht_pos(frame);
+
+  register_xalloc(info, +1);
+
+  void *data = buf + reserved;
+
+  return data;
+}
+
+static malloc_info *get_info(void *data_void) {
+  char *data = static_cast<char *>(data_void);
+  auto *buf = data - reserved;
+
+  auto *info = reinterpret_cast<malloc_info *>(buf);
+  assert(info->magic == malloc_info_magic);
+  return info;
+}
+
+void *malloc(std::size_t size) {
+  return malloc_with_frame(size, get_backtrace());
+}
+
+void free(void *data_void) {
+  if (data_void == nullptr) {
+    return;
+  }
+  auto *info = get_info(data_void);
+  register_xalloc(info, -1);
+
+#if TD_DARWIN
+  static void *free_void = dlsym(RTLD_NEXT, "free");
+  static auto free_old = *reinterpret_cast<decltype(free) **>(&free_void);
+#else
+  extern decltype(free) __libc_free;
+  static auto free_old = __libc_free;
+#endif
+  return free_old(info);
+}
+void *calloc(std::size_t size_a, std::size_t size_b) {
+  auto size = size_a * size_b;
+  void *res = malloc_with_frame(size, get_backtrace());
+  std::memset(res, 0, size);
+  return res;
+}
+void *realloc(void *ptr, std::size_t size) {
+  if (ptr == nullptr) {
+    return malloc_with_frame(size, get_backtrace());
+  }
+  auto *info = get_info(ptr);
+  auto *new_ptr = malloc_with_frame(size, get_backtrace());
+  auto to_copy = std::min(static_cast<std::int32_t>(size), info->size);
+  std::memcpy(new_ptr, ptr, to_copy);
+  free(ptr);
+  return new_ptr;
+}
+void *memalign(std::size_t aligment, std::size_t size) {
+  assert(false && "Memalign is unsupported");
+  return nullptr;
+}
+}
+
+// c++14 guarantees than it is enough to override this two operators.
+void *operator new(std::size_t count) {
+  return malloc_with_frame(count, get_backtrace());
+}
+void operator delete(void *ptr) noexcept(true) {
+  free(ptr);
+}
+// because of gcc warning: the program should also define 'void operator delete(void*, std::size_t)'
+void operator delete(void *ptr, std::size_t) noexcept(true) {
+  free(ptr);
+}
+
+// c++17
+// void *operator new(std::size_t count, std::align_val_t al);
+// void operator delete(void *ptr, std::align_val_t al);
+
+#else
+bool is_memprof_on() {
+  return false;
+}
+void dump_alloc(const std::function<void(const AllocInfo &)> &func) {
+}
+double get_fast_backtrace_success_rate() {
+  return 0;
+}
+std::size_t get_ht_size() {
+  return 0;
+}
+#endif
+
+std::size_t get_used_memory_size() {
+  std::size_t res = 0;
+  dump_alloc([&](const auto info) { res += info.size; });
+  return res;
+}
diff --git a/libs/tdlib/td/memprof/memprof.h b/libs/tdlib/td/memprof/memprof.h
new file mode 100644
index 0000000000..00e33f7380
--- /dev/null
+++ b/libs/tdlib/td/memprof/memprof.h
@@ -0,0 +1,27 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include <array>
+#include <cstddef>
+#include <functional>
+
+constexpr std::size_t BACKTRACE_SHIFT = 2;
+constexpr std::size_t BACKTRACE_HASHED_LENGTH = 6;
+constexpr std::size_t BACKTRACE_LENGTH = 10;
+
+using Backtrace = std::array<void *, BACKTRACE_LENGTH>;
+struct AllocInfo {
+  Backtrace backtrace;
+  std::size_t size;
+};
+
+bool is_memprof_on();
+std::size_t get_ht_size();
+double get_fast_backtrace_success_rate();
+void dump_alloc(const std::function<void(const AllocInfo &)> &func);
+std::size_t get_used_memory_size();
diff --git a/libs/tdlib/td/sqlite/CMakeLists.txt b/libs/tdlib/td/sqlite/CMakeLists.txt
new file mode 100644
index 0000000000..c94efe4f57
--- /dev/null
+++ b/libs/tdlib/td/sqlite/CMakeLists.txt
@@ -0,0 +1,52 @@
+cmake_minimum_required(VERSION 3.0.2 FATAL_ERROR)
+
+if (NOT OPENSSL_FOUND)
+  find_package(OpenSSL REQUIRED)
+  find_package(ZLIB REQUIRED)
+endif()
+
+set(SQLITE_SOURCE
+  sqlite/sqlite3.c
+
+  sqlite/sqlite3.h
+  sqlite/sqlite3ext.h
+  sqlite/sqlite3session.h
+)
+
+add_library(tdsqlite STATIC ${SQLITE_SOURCE})
+target_include_directories(tdsqlite PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>)
+target_include_directories(tdsqlite SYSTEM PRIVATE ${OPENSSL_INCLUDE_DIR})
+target_link_libraries(tdsqlite PRIVATE ${OPENSSL_CRYPTO_LIBRARY} ${CMAKE_DL_LIBS} ${ZLIB_LIBRARIES})
+target_compile_definitions(tdsqlite PRIVATE
+  -DSQLITE_DEFAULT_MEMSTATUS=0
+  -DSQLITE_OMIT_LOAD_EXTENSION
+  -DSQLITE_OMIT_DECLTYPE
+  -DSQLITE_OMIT_PROGRESS_CALLBACK
+  #-DSQLITE_OMIT_DEPRECATED  # SQLCipher uses deprecated sqlite3_profile
+  #-DSQLITE_OMIT_SHARED_CACHE
+)
+target_compile_definitions(tdsqlite PRIVATE -DSQLITE_HAS_CODEC -DSQLITE_TEMP_STORE=2 -DSQLITE_ENABLE_FTS5 -DSQLITE_DISABLE_LFS)
+
+if (NOT WIN32)
+  target_compile_definitions(tdsqlite PRIVATE -DHAVE_USLEEP -DNDEBUG=1)
+endif()
+
+if ("${CMAKE_SYSTEM_NAME}" STREQUAL "WindowsStore")
+  target_compile_definitions(tdsqlite PRIVATE -DSQLITE_OS_WINRT=1)
+endif()
+
+if (GCC OR CLANG)
+  target_compile_options(tdsqlite PRIVATE -Wno-deprecated-declarations -Wno-unused-variable -Wno-unused-const-variable -Wno-unused-function)
+  if (CLANG)
+    target_compile_options(tdsqlite PRIVATE -Wno-parentheses-equality -Wno-unused-value)
+  endif()
+elseif (MSVC)
+  target_compile_options(tdsqlite PRIVATE /wd4996)
+endif()
+
+install(TARGETS tdsqlite EXPORT TdTargets
+  LIBRARY DESTINATION lib
+  ARCHIVE DESTINATION lib
+  RUNTIME DESTINATION bin
+  INCLUDES DESTINATION include
+)
diff --git a/libs/tdlib/td/sqlite/sqlite/LICENSE b/libs/tdlib/td/sqlite/sqlite/LICENSE
new file mode 100644
index 0000000000..4fdcf4ed4c
--- /dev/null
+++ b/libs/tdlib/td/sqlite/sqlite/LICENSE
@@ -0,0 +1,24 @@
+Copyright (c) 2008, ZETETIC LLC
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+    * Neither the name of the ZETETIC LLC nor the
+      names of its contributors may be used to endorse or promote products
+      derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY ZETETIC LLC ''AS IS'' AND ANY
+EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL ZETETIC LLC BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
\ No newline at end of file
diff --git a/libs/tdlib/td/sqlite/sqlite/sqlite3.c b/libs/tdlib/td/sqlite/sqlite/sqlite3.c
new file mode 100644
index 0000000000..a7bb6243ca
--- /dev/null
+++ b/libs/tdlib/td/sqlite/sqlite/sqlite3.c
@@ -0,0 +1,202634 @@
+/******************************************************************************
+** This file is an amalgamation of many separate C source files from SQLite
+** version 3.15.2.  By combining all the individual C code files into this
+** single large file, the entire code can be compiled as a single translation
+** unit.  This allows many compilers to do optimizations that would not be
+** possible if the files were compiled separately.  Performance improvements
+** of 5% or more are commonly seen when SQLite is compiled as a single
+** translation unit.
+**
+** This file is all you need to compile SQLite.  To use SQLite in other
+** programs, you need this file and the "sqlite3.h" header file that defines
+** the programming interface to the SQLite library.  (If you do not have
+** the "sqlite3.h" header file at hand, you will find a copy embedded within
+** the text of this file.  Search for "Begin file sqlite3.h" to find the start
+** of the embedded sqlite3.h header file.) Additional code files may be needed
+** if you want a wrapper to interface SQLite with your choice of programming
+** language. The code for the "sqlite3" command-line shell is also in a
+** separate file. This file contains only code for the core SQLite library.
+*/
+#define SQLITE_CORE 1
+#define SQLITE_AMALGAMATION 1
+#ifndef SQLITE_PRIVATE
+# define SQLITE_PRIVATE static
+#endif
+/************** Begin file sqliteInt.h ***************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** Internal interface definitions for SQLite.
+**
+*/
+#ifndef SQLITEINT_H
+#define SQLITEINT_H
+
+/* Special Comments:
+**
+** Some comments have special meaning to the tools that measure test
+** coverage:
+**
+**    NO_TEST                     - The branches on this line are not
+**                                  measured by branch coverage.  This is
+**                                  used on lines of code that actually
+**                                  implement parts of coverage testing.
+**
+**    OPTIMIZATION-IF-TRUE        - This branch is allowed to alway be false
+**                                  and the correct answer is still obtained,
+**                                  though perhaps more slowly.
+**
+**    OPTIMIZATION-IF-FALSE       - This branch is allowed to alway be true
+**                                  and the correct answer is still obtained,
+**                                  though perhaps more slowly.
+**
+**    PREVENTS-HARMLESS-OVERREAD  - This branch prevents a buffer overread
+**                                  that would be harmless and undetectable
+**                                  if it did occur.  
+**
+** In all cases, the special comment must be enclosed in the usual
+** slash-asterisk...asterisk-slash comment marks, with no spaces between the 
+** asterisks and the comment text.
+*/
+
+/*
+** Make sure the Tcl calling convention macro is defined.  This macro is
+** only used by test code and Tcl integration code.
+*/
+#ifndef SQLITE_TCLAPI
+#  define SQLITE_TCLAPI
+#endif
+
+/*
+** Make sure that rand_s() is available on Windows systems with MSVC 2005
+** or higher.
+*/
+#if defined(_MSC_VER) && _MSC_VER>=1400
+#  define _CRT_RAND_S
+#endif
+
+/*
+** Include the header file used to customize the compiler options for MSVC.
+** This should be done first so that it can successfully prevent spurious
+** compiler warnings due to subsequent content in this file and other files
+** that are included by this file.
+*/
+/************** Include msvc.h in the middle of sqliteInt.h ******************/
+/************** Begin file msvc.h ********************************************/
+/*
+** 2015 January 12
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains code that is specific to MSVC.
+*/
+#ifndef SQLITE_MSVC_H
+#define SQLITE_MSVC_H
+
+#if defined(_MSC_VER)
+#pragma warning(disable : 4054)
+#pragma warning(disable : 4055)
+#pragma warning(disable : 4100)
+#pragma warning(disable : 4127)
+#pragma warning(disable : 4130)
+#pragma warning(disable : 4152)
+#pragma warning(disable : 4189)
+#pragma warning(disable : 4206)
+#pragma warning(disable : 4210)
+#pragma warning(disable : 4232)
+#pragma warning(disable : 4244)
+#pragma warning(disable : 4305)
+#pragma warning(disable : 4306)
+#pragma warning(disable : 4702)
+#pragma warning(disable : 4706)
+#endif /* defined(_MSC_VER) */
+
+#endif /* SQLITE_MSVC_H */
+
+/************** End of msvc.h ************************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+
+/*
+** Special setup for VxWorks
+*/
+/************** Include vxworks.h in the middle of sqliteInt.h ***************/
+/************** Begin file vxworks.h *****************************************/
+/*
+** 2015-03-02
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains code that is specific to Wind River's VxWorks
+*/
+#if defined(__RTP__) || defined(_WRS_KERNEL)
+/* This is VxWorks.  Set up things specially for that OS
+*/
+#include <vxWorks.h>
+#include <pthread.h>  /* amalgamator: dontcache */
+#define OS_VXWORKS 1
+#define SQLITE_OS_OTHER 0
+#define SQLITE_HOMEGROWN_RECURSIVE_MUTEX 1
+#define SQLITE_OMIT_LOAD_EXTENSION 1
+#define SQLITE_ENABLE_LOCKING_STYLE 0
+#define HAVE_UTIME 1
+#else
+/* This is not VxWorks. */
+#define OS_VXWORKS 0
+#define HAVE_FCHOWN 1
+#define HAVE_READLINK 1
+#define HAVE_LSTAT 1
+#endif /* defined(_WRS_KERNEL) */
+
+/************** End of vxworks.h *********************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+
+/*
+** These #defines should enable >2GB file support on POSIX if the
+** underlying operating system supports it.  If the OS lacks
+** large file support, or if the OS is windows, these should be no-ops.
+**
+** Ticket #2739:  The _LARGEFILE_SOURCE macro must appear before any
+** system #includes.  Hence, this block of code must be the very first
+** code in all source files.
+**
+** Large file support can be disabled using the -DSQLITE_DISABLE_LFS switch
+** on the compiler command line.  This is necessary if you are compiling
+** on a recent machine (ex: Red Hat 7.2) but you want your code to work
+** on an older machine (ex: Red Hat 6.0).  If you compile on Red Hat 7.2
+** without this option, LFS is enable.  But LFS does not exist in the kernel
+** in Red Hat 6.0, so the code won't work.  Hence, for maximum binary
+** portability you should omit LFS.
+**
+** The previous paragraph was written in 2005.  (This paragraph is written
+** on 2008-11-28.) These days, all Linux kernels support large files, so
+** you should probably leave LFS enabled.  But some embedded platforms might
+** lack LFS in which case the SQLITE_DISABLE_LFS macro might still be useful.
+**
+** Similar is true for Mac OS X.  LFS is only supported on Mac OS X 9 and later.
+*/
+#ifndef SQLITE_DISABLE_LFS
+# define _LARGE_FILE       1
+# ifndef _FILE_OFFSET_BITS
+#   define _FILE_OFFSET_BITS 64
+# endif
+# define _LARGEFILE_SOURCE 1
+#endif
+
+/* What version of GCC is being used.  0 means GCC is not being used */
+#ifdef __GNUC__
+# define GCC_VERSION (__GNUC__*1000000+__GNUC_MINOR__*1000+__GNUC_PATCHLEVEL__)
+#else
+# define GCC_VERSION 0
+#endif
+
+/* Needed for various definitions... */
+#if defined(__GNUC__) && !defined(_GNU_SOURCE)
+# define _GNU_SOURCE
+#endif
+
+#if defined(__OpenBSD__) && !defined(_BSD_SOURCE)
+# define _BSD_SOURCE
+#endif
+
+/*
+** For MinGW, check to see if we can include the header file containing its
+** version information, among other things.  Normally, this internal MinGW
+** header file would [only] be included automatically by other MinGW header
+** files; however, the contained version information is now required by this
+** header file to work around binary compatibility issues (see below) and
+** this is the only known way to reliably obtain it.  This entire #if block
+** would be completely unnecessary if there was any other way of detecting
+** MinGW via their preprocessor (e.g. if they customized their GCC to define
+** some MinGW-specific macros).  When compiling for MinGW, either the
+** _HAVE_MINGW_H or _HAVE__MINGW_H (note the extra underscore) macro must be
+** defined; otherwise, detection of conditions specific to MinGW will be
+** disabled.
+*/
+#if defined(_HAVE_MINGW_H)
+# include "mingw.h"
+#elif defined(_HAVE__MINGW_H)
+# include "_mingw.h"
+#endif
+
+/*
+** For MinGW version 4.x (and higher), check to see if the _USE_32BIT_TIME_T
+** define is required to maintain binary compatibility with the MSVC runtime
+** library in use (e.g. for Windows XP).
+*/
+#if !defined(_USE_32BIT_TIME_T) && !defined(_USE_64BIT_TIME_T) && \
+    defined(_WIN32) && !defined(_WIN64) && \
+    defined(__MINGW_MAJOR_VERSION) && __MINGW_MAJOR_VERSION >= 4 && \
+    defined(__MSVCRT__)
+# define _USE_32BIT_TIME_T
+#endif
+
+/* The public SQLite interface.  The _FILE_OFFSET_BITS macro must appear
+** first in QNX.  Also, the _USE_32BIT_TIME_T macro must appear first for
+** MinGW.
+*/
+/************** Include sqlite3.h in the middle of sqliteInt.h ***************/
+/************** Begin file sqlite3.h *****************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This header file defines the interface that the SQLite library
+** presents to client programs.  If a C-function, structure, datatype,
+** or constant definition does not appear in this file, then it is
+** not a published API of SQLite, is subject to change without
+** notice, and should not be referenced by programs that use SQLite.
+**
+** Some of the definitions that are in this file are marked as
+** "experimental".  Experimental interfaces are normally new
+** features recently added to SQLite.  We do not anticipate changes
+** to experimental interfaces but reserve the right to make minor changes
+** if experience from use "in the wild" suggest such changes are prudent.
+**
+** The official C-language API documentation for SQLite is derived
+** from comments in this file.  This file is the authoritative source
+** on how SQLite interfaces are supposed to operate.
+**
+** The name of this file under configuration management is "sqlite.h.in".
+** The makefile makes some minor changes to this file (such as inserting
+** the version number) and changes its name to "sqlite3.h" as
+** part of the build process.
+*/
+#ifndef SQLITE3_H
+#define SQLITE3_H
+#include <stdarg.h>     /* Needed for the definition of va_list */
+
+/*
+** Make sure we can call this stuff from C++.
+*/
+#if 0
+extern "C" {
+#endif
+
+
+/*
+** Provide the ability to override linkage features of the interface.
+*/
+#ifndef SQLITE_EXTERN
+# define SQLITE_EXTERN extern
+#endif
+#ifndef SQLITE_API
+# define SQLITE_API
+#endif
+#ifndef SQLITE_CDECL
+# define SQLITE_CDECL
+#endif
+#ifndef SQLITE_APICALL
+# define SQLITE_APICALL
+#endif
+#ifndef SQLITE_STDCALL
+# define SQLITE_STDCALL SQLITE_APICALL
+#endif
+#ifndef SQLITE_CALLBACK
+# define SQLITE_CALLBACK
+#endif
+#ifndef SQLITE_SYSAPI
+# define SQLITE_SYSAPI
+#endif
+
+/*
+** These no-op macros are used in front of interfaces to mark those
+** interfaces as either deprecated or experimental.  New applications
+** should not use deprecated interfaces - they are supported for backwards
+** compatibility only.  Application writers should be aware that
+** experimental interfaces are subject to change in point releases.
+**
+** These macros used to resolve to various kinds of compiler magic that
+** would generate warning messages when they were used.  But that
+** compiler magic ended up generating such a flurry of bug reports
+** that we have taken it all out and gone back to using simple
+** noop macros.
+*/
+#define SQLITE_DEPRECATED
+#define SQLITE_EXPERIMENTAL
+
+/*
+** Ensure these symbols were not defined by some previous header file.
+*/
+#ifdef SQLITE_VERSION
+# undef SQLITE_VERSION
+#endif
+#ifdef SQLITE_VERSION_NUMBER
+# undef SQLITE_VERSION_NUMBER
+#endif
+
+/*
+** CAPI3REF: Compile-Time Library Version Numbers
+**
+** ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header
+** evaluates to a string literal that is the SQLite version in the
+** format "X.Y.Z" where X is the major version number (always 3 for
+** SQLite3) and Y is the minor version number and Z is the release number.)^
+** ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves to an integer
+** with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z are the same
+** numbers used in [SQLITE_VERSION].)^
+** The SQLITE_VERSION_NUMBER for any given release of SQLite will also
+** be larger than the release from which it is derived.  Either Y will
+** be held constant and Z will be incremented or else Y will be incremented
+** and Z will be reset to zero.
+**
+** Since [version 3.6.18] ([dateof:3.6.18]), 
+** SQLite source code has been stored in the
+** <a href="http://www.fossil-scm.org/">Fossil configuration management
+** system</a>.  ^The SQLITE_SOURCE_ID macro evaluates to
+** a string which identifies a particular check-in of SQLite
+** within its configuration management system.  ^The SQLITE_SOURCE_ID
+** string contains the date and time of the check-in (UTC) and an SHA1
+** hash of the entire source tree.
+**
+** See also: [sqlite3_libversion()],
+** [sqlite3_libversion_number()], [sqlite3_sourceid()],
+** [sqlite_version()] and [sqlite_source_id()].
+*/
+#define SQLITE_VERSION        "3.15.2"
+#define SQLITE_VERSION_NUMBER 3015002
+#define SQLITE_SOURCE_ID      "2016-11-28 19:13:37 bbd85d235f7037c6a033a9690534391ffeacecc8"
+
+/*
+** CAPI3REF: Run-Time Library Version Numbers
+** KEYWORDS: sqlite3_version, sqlite3_sourceid
+**
+** These interfaces provide the same information as the [SQLITE_VERSION],
+** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
+** but are associated with the library instead of the header file.  ^(Cautious
+** programmers might include assert() statements in their application to
+** verify that values returned by these interfaces match the macros in
+** the header, and thus ensure that the application is
+** compiled with matching library and header files.
+**
+** <blockquote><pre>
+** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );
+** assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 );
+** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );
+** </pre></blockquote>)^
+**
+** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION]
+** macro.  ^The sqlite3_libversion() function returns a pointer to the
+** to the sqlite3_version[] string constant.  The sqlite3_libversion()
+** function is provided for use in DLLs since DLL users usually do not have
+** direct access to string constants within the DLL.  ^The
+** sqlite3_libversion_number() function returns an integer equal to
+** [SQLITE_VERSION_NUMBER].  ^The sqlite3_sourceid() function returns 
+** a pointer to a string constant whose value is the same as the 
+** [SQLITE_SOURCE_ID] C preprocessor macro.
+**
+** See also: [sqlite_version()] and [sqlite_source_id()].
+*/
+SQLITE_API const char sqlite3_version[] = SQLITE_VERSION;
+SQLITE_API const char *sqlite3_libversion(void);
+SQLITE_API const char *sqlite3_sourceid(void);
+SQLITE_API int sqlite3_libversion_number(void);
+
+/*
+** CAPI3REF: Run-Time Library Compilation Options Diagnostics
+**
+** ^The sqlite3_compileoption_used() function returns 0 or 1 
+** indicating whether the specified option was defined at 
+** compile time.  ^The SQLITE_ prefix may be omitted from the 
+** option name passed to sqlite3_compileoption_used().  
+**
+** ^The sqlite3_compileoption_get() function allows iterating
+** over the list of options that were defined at compile time by
+** returning the N-th compile time option string.  ^If N is out of range,
+** sqlite3_compileoption_get() returns a NULL pointer.  ^The SQLITE_ 
+** prefix is omitted from any strings returned by 
+** sqlite3_compileoption_get().
+**
+** ^Support for the diagnostic functions sqlite3_compileoption_used()
+** and sqlite3_compileoption_get() may be omitted by specifying the 
+** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time.
+**
+** See also: SQL functions [sqlite_compileoption_used()] and
+** [sqlite_compileoption_get()] and the [compile_options pragma].
+*/
+#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
+SQLITE_API int sqlite3_compileoption_used(const char *zOptName);
+SQLITE_API const char *sqlite3_compileoption_get(int N);
+#endif
+
+/*
+** CAPI3REF: Test To See If The Library Is Threadsafe
+**
+** ^The sqlite3_threadsafe() function returns zero if and only if
+** SQLite was compiled with mutexing code omitted due to the
+** [SQLITE_THREADSAFE] compile-time option being set to 0.
+**
+** SQLite can be compiled with or without mutexes.  When
+** the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes
+** are enabled and SQLite is threadsafe.  When the
+** [SQLITE_THREADSAFE] macro is 0, 
+** the mutexes are omitted.  Without the mutexes, it is not safe
+** to use SQLite concurrently from more than one thread.
+**
+** Enabling mutexes incurs a measurable performance penalty.
+** So if speed is of utmost importance, it makes sense to disable
+** the mutexes.  But for maximum safety, mutexes should be enabled.
+** ^The default behavior is for mutexes to be enabled.
+**
+** This interface can be used by an application to make sure that the
+** version of SQLite that it is linking against was compiled with
+** the desired setting of the [SQLITE_THREADSAFE] macro.
+**
+** This interface only reports on the compile-time mutex setting
+** of the [SQLITE_THREADSAFE] flag.  If SQLite is compiled with
+** SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but
+** can be fully or partially disabled using a call to [sqlite3_config()]
+** with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD],
+** or [SQLITE_CONFIG_SERIALIZED].  ^(The return value of the
+** sqlite3_threadsafe() function shows only the compile-time setting of
+** thread safety, not any run-time changes to that setting made by
+** sqlite3_config(). In other words, the return value from sqlite3_threadsafe()
+** is unchanged by calls to sqlite3_config().)^
+**
+** See the [threading mode] documentation for additional information.
+*/
+SQLITE_API int sqlite3_threadsafe(void);
+
+/*
+** CAPI3REF: Database Connection Handle
+** KEYWORDS: {database connection} {database connections}
+**
+** Each open SQLite database is represented by a pointer to an instance of
+** the opaque structure named "sqlite3".  It is useful to think of an sqlite3
+** pointer as an object.  The [sqlite3_open()], [sqlite3_open16()], and
+** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
+** and [sqlite3_close_v2()] are its destructors.  There are many other
+** interfaces (such as
+** [sqlite3_prepare_v2()], [sqlite3_create_function()], and
+** [sqlite3_busy_timeout()] to name but three) that are methods on an
+** sqlite3 object.
+*/
+typedef struct sqlite3 sqlite3;
+
+/*
+** CAPI3REF: 64-Bit Integer Types
+** KEYWORDS: sqlite_int64 sqlite_uint64
+**
+** Because there is no cross-platform way to specify 64-bit integer types
+** SQLite includes typedefs for 64-bit signed and unsigned integers.
+**
+** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.
+** The sqlite_int64 and sqlite_uint64 types are supported for backwards
+** compatibility only.
+**
+** ^The sqlite3_int64 and sqlite_int64 types can store integer values
+** between -9223372036854775808 and +9223372036854775807 inclusive.  ^The
+** sqlite3_uint64 and sqlite_uint64 types can store integer values 
+** between 0 and +18446744073709551615 inclusive.
+*/
+#ifdef SQLITE_INT64_TYPE
+  typedef SQLITE_INT64_TYPE sqlite_int64;
+  typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
+#elif defined(_MSC_VER) || defined(__BORLANDC__)
+  typedef __int64 sqlite_int64;
+  typedef unsigned __int64 sqlite_uint64;
+#else
+  typedef long long int sqlite_int64;
+  typedef unsigned long long int sqlite_uint64;
+#endif
+typedef sqlite_int64 sqlite3_int64;
+typedef sqlite_uint64 sqlite3_uint64;
+
+/*
+** If compiling for a processor that lacks floating point support,
+** substitute integer for floating-point.
+*/
+#ifdef SQLITE_OMIT_FLOATING_POINT
+# define double sqlite3_int64
+#endif
+
+/*
+** CAPI3REF: Closing A Database Connection
+** DESTRUCTOR: sqlite3
+**
+** ^The sqlite3_close() and sqlite3_close_v2() routines are destructors
+** for the [sqlite3] object.
+** ^Calls to sqlite3_close() and sqlite3_close_v2() return [SQLITE_OK] if
+** the [sqlite3] object is successfully destroyed and all associated
+** resources are deallocated.
+**
+** ^If the database connection is associated with unfinalized prepared
+** statements or unfinished sqlite3_backup objects then sqlite3_close()
+** will leave the database connection open and return [SQLITE_BUSY].
+** ^If sqlite3_close_v2() is called with unfinalized prepared statements
+** and/or unfinished sqlite3_backups, then the database connection becomes
+** an unusable "zombie" which will automatically be deallocated when the
+** last prepared statement is finalized or the last sqlite3_backup is
+** finished.  The sqlite3_close_v2() interface is intended for use with
+** host languages that are garbage collected, and where the order in which
+** destructors are called is arbitrary.
+**
+** Applications should [sqlite3_finalize | finalize] all [prepared statements],
+** [sqlite3_blob_close | close] all [BLOB handles], and 
+** [sqlite3_backup_finish | finish] all [sqlite3_backup] objects associated
+** with the [sqlite3] object prior to attempting to close the object.  ^If
+** sqlite3_close_v2() is called on a [database connection] that still has
+** outstanding [prepared statements], [BLOB handles], and/or
+** [sqlite3_backup] objects then it returns [SQLITE_OK] and the deallocation
+** of resources is deferred until all [prepared statements], [BLOB handles],
+** and [sqlite3_backup] objects are also destroyed.
+**
+** ^If an [sqlite3] object is destroyed while a transaction is open,
+** the transaction is automatically rolled back.
+**
+** The C parameter to [sqlite3_close(C)] and [sqlite3_close_v2(C)]
+** must be either a NULL
+** pointer or an [sqlite3] object pointer obtained
+** from [sqlite3_open()], [sqlite3_open16()], or
+** [sqlite3_open_v2()], and not previously closed.
+** ^Calling sqlite3_close() or sqlite3_close_v2() with a NULL pointer
+** argument is a harmless no-op.
+*/
+SQLITE_API int sqlite3_close(sqlite3*);
+SQLITE_API int sqlite3_close_v2(sqlite3*);
+
+/*
+** The type for a callback function.
+** This is legacy and deprecated.  It is included for historical
+** compatibility and is not documented.
+*/
+typedef int (*sqlite3_callback)(void*,int,char**, char**);
+
+/*
+** CAPI3REF: One-Step Query Execution Interface
+** METHOD: sqlite3
+**
+** The sqlite3_exec() interface is a convenience wrapper around
+** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()],
+** that allows an application to run multiple statements of SQL
+** without having to use a lot of C code. 
+**
+** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
+** semicolon-separate SQL statements passed into its 2nd argument,
+** in the context of the [database connection] passed in as its 1st
+** argument.  ^If the callback function of the 3rd argument to
+** sqlite3_exec() is not NULL, then it is invoked for each result row
+** coming out of the evaluated SQL statements.  ^The 4th argument to
+** sqlite3_exec() is relayed through to the 1st argument of each
+** callback invocation.  ^If the callback pointer to sqlite3_exec()
+** is NULL, then no callback is ever invoked and result rows are
+** ignored.
+**
+** ^If an error occurs while evaluating the SQL statements passed into
+** sqlite3_exec(), then execution of the current statement stops and
+** subsequent statements are skipped.  ^If the 5th parameter to sqlite3_exec()
+** is not NULL then any error message is written into memory obtained
+** from [sqlite3_malloc()] and passed back through the 5th parameter.
+** To avoid memory leaks, the application should invoke [sqlite3_free()]
+** on error message strings returned through the 5th parameter of
+** sqlite3_exec() after the error message string is no longer needed.
+** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors
+** occur, then sqlite3_exec() sets the pointer in its 5th parameter to
+** NULL before returning.
+**
+** ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec()
+** routine returns SQLITE_ABORT without invoking the callback again and
+** without running any subsequent SQL statements.
+**
+** ^The 2nd argument to the sqlite3_exec() callback function is the
+** number of columns in the result.  ^The 3rd argument to the sqlite3_exec()
+** callback is an array of pointers to strings obtained as if from
+** [sqlite3_column_text()], one for each column.  ^If an element of a
+** result row is NULL then the corresponding string pointer for the
+** sqlite3_exec() callback is a NULL pointer.  ^The 4th argument to the
+** sqlite3_exec() callback is an array of pointers to strings where each
+** entry represents the name of corresponding result column as obtained
+** from [sqlite3_column_name()].
+**
+** ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer
+** to an empty string, or a pointer that contains only whitespace and/or 
+** SQL comments, then no SQL statements are evaluated and the database
+** is not changed.
+**
+** Restrictions:
+**
+** <ul>
+** <li> The application must ensure that the 1st parameter to sqlite3_exec()
+**      is a valid and open [database connection].
+** <li> The application must not close the [database connection] specified by
+**      the 1st parameter to sqlite3_exec() while sqlite3_exec() is running.
+** <li> The application must not modify the SQL statement text passed into
+**      the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running.
+** </ul>
+*/
+SQLITE_API int sqlite3_exec(
+  sqlite3*,                                  /* An open database */
+  const char *sql,                           /* SQL to be evaluated */
+  int (*callback)(void*,int,char**,char**),  /* Callback function */
+  void *,                                    /* 1st argument to callback */
+  char **errmsg                              /* Error msg written here */
+);
+
+/*
+** CAPI3REF: Result Codes
+** KEYWORDS: {result code definitions}
+**
+** Many SQLite functions return an integer result code from the set shown
+** here in order to indicate success or failure.
+**
+** New error codes may be added in future versions of SQLite.
+**
+** See also: [extended result code definitions]
+*/
+#define SQLITE_OK           0   /* Successful result */
+/* beginning-of-error-codes */
+#define SQLITE_ERROR        1   /* SQL error or missing database */
+#define SQLITE_INTERNAL     2   /* Internal logic error in SQLite */
+#define SQLITE_PERM         3   /* Access permission denied */
+#define SQLITE_ABORT        4   /* Callback routine requested an abort */
+#define SQLITE_BUSY         5   /* The database file is locked */
+#define SQLITE_LOCKED       6   /* A table in the database is locked */
+#define SQLITE_NOMEM        7   /* A malloc() failed */
+#define SQLITE_READONLY     8   /* Attempt to write a readonly database */
+#define SQLITE_INTERRUPT    9   /* Operation terminated by sqlite3_interrupt()*/
+#define SQLITE_IOERR       10   /* Some kind of disk I/O error occurred */
+#define SQLITE_CORRUPT     11   /* The database disk image is malformed */
+#define SQLITE_NOTFOUND    12   /* Unknown opcode in sqlite3_file_control() */
+#define SQLITE_FULL        13   /* Insertion failed because database is full */
+#define SQLITE_CANTOPEN    14   /* Unable to open the database file */
+#define SQLITE_PROTOCOL    15   /* Database lock protocol error */
+#define SQLITE_EMPTY       16   /* Database is empty */
+#define SQLITE_SCHEMA      17   /* The database schema changed */
+#define SQLITE_TOOBIG      18   /* String or BLOB exceeds size limit */
+#define SQLITE_CONSTRAINT  19   /* Abort due to constraint violation */
+#define SQLITE_MISMATCH    20   /* Data type mismatch */
+#define SQLITE_MISUSE      21   /* Library used incorrectly */
+#define SQLITE_NOLFS       22   /* Uses OS features not supported on host */
+#define SQLITE_AUTH        23   /* Authorization denied */
+#define SQLITE_FORMAT      24   /* Auxiliary database format error */
+#define SQLITE_RANGE       25   /* 2nd parameter to sqlite3_bind out of range */
+#define SQLITE_NOTADB      26   /* File opened that is not a database file */
+#define SQLITE_NOTICE      27   /* Notifications from sqlite3_log() */
+#define SQLITE_WARNING     28   /* Warnings from sqlite3_log() */
+#define SQLITE_ROW         100  /* sqlite3_step() has another row ready */
+#define SQLITE_DONE        101  /* sqlite3_step() has finished executing */
+/* end-of-error-codes */
+
+/*
+** CAPI3REF: Extended Result Codes
+** KEYWORDS: {extended result code definitions}
+**
+** In its default configuration, SQLite API routines return one of 30 integer
+** [result codes].  However, experience has shown that many of
+** these result codes are too coarse-grained.  They do not provide as
+** much information about problems as programmers might like.  In an effort to
+** address this, newer versions of SQLite (version 3.3.8 [dateof:3.3.8]
+** and later) include
+** support for additional result codes that provide more detailed information
+** about errors. These [extended result codes] are enabled or disabled
+** on a per database connection basis using the
+** [sqlite3_extended_result_codes()] API.  Or, the extended code for
+** the most recent error can be obtained using
+** [sqlite3_extended_errcode()].
+*/
+#define SQLITE_IOERR_READ              (SQLITE_IOERR | (1<<8))
+#define SQLITE_IOERR_SHORT_READ        (SQLITE_IOERR | (2<<8))
+#define SQLITE_IOERR_WRITE             (SQLITE_IOERR | (3<<8))
+#define SQLITE_IOERR_FSYNC             (SQLITE_IOERR | (4<<8))
+#define SQLITE_IOERR_DIR_FSYNC         (SQLITE_IOERR | (5<<8))
+#define SQLITE_IOERR_TRUNCATE          (SQLITE_IOERR | (6<<8))
+#define SQLITE_IOERR_FSTAT             (SQLITE_IOERR | (7<<8))
+#define SQLITE_IOERR_UNLOCK            (SQLITE_IOERR | (8<<8))
+#define SQLITE_IOERR_RDLOCK            (SQLITE_IOERR | (9<<8))
+#define SQLITE_IOERR_DELETE            (SQLITE_IOERR | (10<<8))
+#define SQLITE_IOERR_BLOCKED           (SQLITE_IOERR | (11<<8))
+#define SQLITE_IOERR_NOMEM             (SQLITE_IOERR | (12<<8))
+#define SQLITE_IOERR_ACCESS            (SQLITE_IOERR | (13<<8))
+#define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))
+#define SQLITE_IOERR_LOCK              (SQLITE_IOERR | (15<<8))
+#define SQLITE_IOERR_CLOSE             (SQLITE_IOERR | (16<<8))
+#define SQLITE_IOERR_DIR_CLOSE         (SQLITE_IOERR | (17<<8))
+#define SQLITE_IOERR_SHMOPEN           (SQLITE_IOERR | (18<<8))
+#define SQLITE_IOERR_SHMSIZE           (SQLITE_IOERR | (19<<8))
+#define SQLITE_IOERR_SHMLOCK           (SQLITE_IOERR | (20<<8))
+#define SQLITE_IOERR_SHMMAP            (SQLITE_IOERR | (21<<8))
+#define SQLITE_IOERR_SEEK              (SQLITE_IOERR | (22<<8))
+#define SQLITE_IOERR_DELETE_NOENT      (SQLITE_IOERR | (23<<8))
+#define SQLITE_IOERR_MMAP              (SQLITE_IOERR | (24<<8))
+#define SQLITE_IOERR_GETTEMPPATH       (SQLITE_IOERR | (25<<8))
+#define SQLITE_IOERR_CONVPATH          (SQLITE_IOERR | (26<<8))
+#define SQLITE_IOERR_VNODE             (SQLITE_IOERR | (27<<8))
+#define SQLITE_IOERR_AUTH              (SQLITE_IOERR | (28<<8))
+#define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
+#define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
+#define SQLITE_BUSY_SNAPSHOT           (SQLITE_BUSY   |  (2<<8))
+#define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
+#define SQLITE_CANTOPEN_ISDIR          (SQLITE_CANTOPEN | (2<<8))
+#define SQLITE_CANTOPEN_FULLPATH       (SQLITE_CANTOPEN | (3<<8))
+#define SQLITE_CANTOPEN_CONVPATH       (SQLITE_CANTOPEN | (4<<8))
+#define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))
+#define SQLITE_READONLY_RECOVERY       (SQLITE_READONLY | (1<<8))
+#define SQLITE_READONLY_CANTLOCK       (SQLITE_READONLY | (2<<8))
+#define SQLITE_READONLY_ROLLBACK       (SQLITE_READONLY | (3<<8))
+#define SQLITE_READONLY_DBMOVED        (SQLITE_READONLY | (4<<8))
+#define SQLITE_ABORT_ROLLBACK          (SQLITE_ABORT | (2<<8))
+#define SQLITE_CONSTRAINT_CHECK        (SQLITE_CONSTRAINT | (1<<8))
+#define SQLITE_CONSTRAINT_COMMITHOOK   (SQLITE_CONSTRAINT | (2<<8))
+#define SQLITE_CONSTRAINT_FOREIGNKEY   (SQLITE_CONSTRAINT | (3<<8))
+#define SQLITE_CONSTRAINT_FUNCTION     (SQLITE_CONSTRAINT | (4<<8))
+#define SQLITE_CONSTRAINT_NOTNULL      (SQLITE_CONSTRAINT | (5<<8))
+#define SQLITE_CONSTRAINT_PRIMARYKEY   (SQLITE_CONSTRAINT | (6<<8))
+#define SQLITE_CONSTRAINT_TRIGGER      (SQLITE_CONSTRAINT | (7<<8))
+#define SQLITE_CONSTRAINT_UNIQUE       (SQLITE_CONSTRAINT | (8<<8))
+#define SQLITE_CONSTRAINT_VTAB         (SQLITE_CONSTRAINT | (9<<8))
+#define SQLITE_CONSTRAINT_ROWID        (SQLITE_CONSTRAINT |(10<<8))
+#define SQLITE_NOTICE_RECOVER_WAL      (SQLITE_NOTICE | (1<<8))
+#define SQLITE_NOTICE_RECOVER_ROLLBACK (SQLITE_NOTICE | (2<<8))
+#define SQLITE_WARNING_AUTOINDEX       (SQLITE_WARNING | (1<<8))
+#define SQLITE_AUTH_USER               (SQLITE_AUTH | (1<<8))
+#define SQLITE_OK_LOAD_PERMANENTLY     (SQLITE_OK | (1<<8))
+
+/*
+** CAPI3REF: Flags For File Open Operations
+**
+** These bit values are intended for use in the
+** 3rd parameter to the [sqlite3_open_v2()] interface and
+** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
+*/
+#define SQLITE_OPEN_READONLY         0x00000001  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_READWRITE        0x00000002  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_CREATE           0x00000004  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_DELETEONCLOSE    0x00000008  /* VFS only */
+#define SQLITE_OPEN_EXCLUSIVE        0x00000010  /* VFS only */
+#define SQLITE_OPEN_AUTOPROXY        0x00000020  /* VFS only */
+#define SQLITE_OPEN_URI              0x00000040  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_MEMORY           0x00000080  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_MAIN_DB          0x00000100  /* VFS only */
+#define SQLITE_OPEN_TEMP_DB          0x00000200  /* VFS only */
+#define SQLITE_OPEN_TRANSIENT_DB     0x00000400  /* VFS only */
+#define SQLITE_OPEN_MAIN_JOURNAL     0x00000800  /* VFS only */
+#define SQLITE_OPEN_TEMP_JOURNAL     0x00001000  /* VFS only */
+#define SQLITE_OPEN_SUBJOURNAL       0x00002000  /* VFS only */
+#define SQLITE_OPEN_MASTER_JOURNAL   0x00004000  /* VFS only */
+#define SQLITE_OPEN_NOMUTEX          0x00008000  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_FULLMUTEX        0x00010000  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_SHAREDCACHE      0x00020000  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_PRIVATECACHE     0x00040000  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_WAL              0x00080000  /* VFS only */
+
+/* Reserved:                         0x00F00000 */
+
+/*
+** CAPI3REF: Device Characteristics
+**
+** The xDeviceCharacteristics method of the [sqlite3_io_methods]
+** object returns an integer which is a vector of these
+** bit values expressing I/O characteristics of the mass storage
+** device that holds the file that the [sqlite3_io_methods]
+** refers to.
+**
+** The SQLITE_IOCAP_ATOMIC property means that all writes of
+** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
+** mean that writes of blocks that are nnn bytes in size and
+** are aligned to an address which is an integer multiple of
+** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
+** that when data is appended to a file, the data is appended
+** first then the size of the file is extended, never the other
+** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
+** information is written to disk in the same order as calls
+** to xWrite().  The SQLITE_IOCAP_POWERSAFE_OVERWRITE property means that
+** after reboot following a crash or power loss, the only bytes in a
+** file that were written at the application level might have changed
+** and that adjacent bytes, even bytes within the same sector are
+** guaranteed to be unchanged.  The SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
+** flag indicate that a file cannot be deleted when open.  The
+** SQLITE_IOCAP_IMMUTABLE flag indicates that the file is on
+** read-only media and cannot be changed even by processes with
+** elevated privileges.
+*/
+#define SQLITE_IOCAP_ATOMIC                 0x00000001
+#define SQLITE_IOCAP_ATOMIC512              0x00000002
+#define SQLITE_IOCAP_ATOMIC1K               0x00000004
+#define SQLITE_IOCAP_ATOMIC2K               0x00000008
+#define SQLITE_IOCAP_ATOMIC4K               0x00000010
+#define SQLITE_IOCAP_ATOMIC8K               0x00000020
+#define SQLITE_IOCAP_ATOMIC16K              0x00000040
+#define SQLITE_IOCAP_ATOMIC32K              0x00000080
+#define SQLITE_IOCAP_ATOMIC64K              0x00000100
+#define SQLITE_IOCAP_SAFE_APPEND            0x00000200
+#define SQLITE_IOCAP_SEQUENTIAL             0x00000400
+#define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN  0x00000800
+#define SQLITE_IOCAP_POWERSAFE_OVERWRITE    0x00001000
+#define SQLITE_IOCAP_IMMUTABLE              0x00002000
+
+/*
+** CAPI3REF: File Locking Levels
+**
+** SQLite uses one of these integer values as the second
+** argument to calls it makes to the xLock() and xUnlock() methods
+** of an [sqlite3_io_methods] object.
+*/
+#define SQLITE_LOCK_NONE          0
+#define SQLITE_LOCK_SHARED        1
+#define SQLITE_LOCK_RESERVED      2
+#define SQLITE_LOCK_PENDING       3
+#define SQLITE_LOCK_EXCLUSIVE     4
+
+/*
+** CAPI3REF: Synchronization Type Flags
+**
+** When SQLite invokes the xSync() method of an
+** [sqlite3_io_methods] object it uses a combination of
+** these integer values as the second argument.
+**
+** When the SQLITE_SYNC_DATAONLY flag is used, it means that the
+** sync operation only needs to flush data to mass storage.  Inode
+** information need not be flushed. If the lower four bits of the flag
+** equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics.
+** If the lower four bits equal SQLITE_SYNC_FULL, that means
+** to use Mac OS X style fullsync instead of fsync().
+**
+** Do not confuse the SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags
+** with the [PRAGMA synchronous]=NORMAL and [PRAGMA synchronous]=FULL
+** settings.  The [synchronous pragma] determines when calls to the
+** xSync VFS method occur and applies uniformly across all platforms.
+** The SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags determine how
+** energetic or rigorous or forceful the sync operations are and
+** only make a difference on Mac OSX for the default SQLite code.
+** (Third-party VFS implementations might also make the distinction
+** between SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL, but among the
+** operating systems natively supported by SQLite, only Mac OSX
+** cares about the difference.)
+*/
+#define SQLITE_SYNC_NORMAL        0x00002
+#define SQLITE_SYNC_FULL          0x00003
+#define SQLITE_SYNC_DATAONLY      0x00010
+
+/*
+** CAPI3REF: OS Interface Open File Handle
+**
+** An [sqlite3_file] object represents an open file in the 
+** [sqlite3_vfs | OS interface layer].  Individual OS interface
+** implementations will
+** want to subclass this object by appending additional fields
+** for their own use.  The pMethods entry is a pointer to an
+** [sqlite3_io_methods] object that defines methods for performing
+** I/O operations on the open file.
+*/
+typedef struct sqlite3_file sqlite3_file;
+struct sqlite3_file {
+  const struct sqlite3_io_methods *pMethods;  /* Methods for an open file */
+};
+
+/*
+** CAPI3REF: OS Interface File Virtual Methods Object
+**
+** Every file opened by the [sqlite3_vfs.xOpen] method populates an
+** [sqlite3_file] object (or, more commonly, a subclass of the
+** [sqlite3_file] object) with a pointer to an instance of this object.
+** This object defines the methods used to perform various operations
+** against the open file represented by the [sqlite3_file] object.
+**
+** If the [sqlite3_vfs.xOpen] method sets the sqlite3_file.pMethods element 
+** to a non-NULL pointer, then the sqlite3_io_methods.xClose method
+** may be invoked even if the [sqlite3_vfs.xOpen] reported that it failed.  The
+** only way to prevent a call to xClose following a failed [sqlite3_vfs.xOpen]
+** is for the [sqlite3_vfs.xOpen] to set the sqlite3_file.pMethods element
+** to NULL.
+**
+** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or
+** [SQLITE_SYNC_FULL].  The first choice is the normal fsync().
+** The second choice is a Mac OS X style fullsync.  The [SQLITE_SYNC_DATAONLY]
+** flag may be ORed in to indicate that only the data of the file
+** and not its inode needs to be synced.
+**
+** The integer values to xLock() and xUnlock() are one of
+** <ul>
+** <li> [SQLITE_LOCK_NONE],
+** <li> [SQLITE_LOCK_SHARED],
+** <li> [SQLITE_LOCK_RESERVED],
+** <li> [SQLITE_LOCK_PENDING], or
+** <li> [SQLITE_LOCK_EXCLUSIVE].
+** </ul>
+** xLock() increases the lock. xUnlock() decreases the lock.
+** The xCheckReservedLock() method checks whether any database connection,
+** either in this process or in some other process, is holding a RESERVED,
+** PENDING, or EXCLUSIVE lock on the file.  It returns true
+** if such a lock exists and false otherwise.
+**
+** The xFileControl() method is a generic interface that allows custom
+** VFS implementations to directly control an open file using the
+** [sqlite3_file_control()] interface.  The second "op" argument is an
+** integer opcode.  The third argument is a generic pointer intended to
+** point to a structure that may contain arguments or space in which to
+** write return values.  Potential uses for xFileControl() might be
+** functions to enable blocking locks with timeouts, to change the
+** locking strategy (for example to use dot-file locks), to inquire
+** about the status of a lock, or to break stale locks.  The SQLite
+** core reserves all opcodes less than 100 for its own use.
+** A [file control opcodes | list of opcodes] less than 100 is available.
+** Applications that define a custom xFileControl method should use opcodes
+** greater than 100 to avoid conflicts.  VFS implementations should
+** return [SQLITE_NOTFOUND] for file control opcodes that they do not
+** recognize.
+**
+** The xSectorSize() method returns the sector size of the
+** device that underlies the file.  The sector size is the
+** minimum write that can be performed without disturbing
+** other bytes in the file.  The xDeviceCharacteristics()
+** method returns a bit vector describing behaviors of the
+** underlying device:
+**
+** <ul>
+** <li> [SQLITE_IOCAP_ATOMIC]
+** <li> [SQLITE_IOCAP_ATOMIC512]
+** <li> [SQLITE_IOCAP_ATOMIC1K]
+** <li> [SQLITE_IOCAP_ATOMIC2K]
+** <li> [SQLITE_IOCAP_ATOMIC4K]
+** <li> [SQLITE_IOCAP_ATOMIC8K]
+** <li> [SQLITE_IOCAP_ATOMIC16K]
+** <li> [SQLITE_IOCAP_ATOMIC32K]
+** <li> [SQLITE_IOCAP_ATOMIC64K]
+** <li> [SQLITE_IOCAP_SAFE_APPEND]
+** <li> [SQLITE_IOCAP_SEQUENTIAL]
+** </ul>
+**
+** The SQLITE_IOCAP_ATOMIC property means that all writes of
+** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
+** mean that writes of blocks that are nnn bytes in size and
+** are aligned to an address which is an integer multiple of
+** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
+** that when data is appended to a file, the data is appended
+** first then the size of the file is extended, never the other
+** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
+** information is written to disk in the same order as calls
+** to xWrite().
+**
+** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill
+** in the unread portions of the buffer with zeros.  A VFS that
+** fails to zero-fill short reads might seem to work.  However,
+** failure to zero-fill short reads will eventually lead to
+** database corruption.
+*/
+typedef struct sqlite3_io_methods sqlite3_io_methods;
+struct sqlite3_io_methods {
+  int iVersion;
+  int (*xClose)(sqlite3_file*);
+  int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
+  int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
+  int (*xTruncate)(sqlite3_file*, sqlite3_int64 size);
+  int (*xSync)(sqlite3_file*, int flags);
+  int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize);
+  int (*xLock)(sqlite3_file*, int);
+  int (*xUnlock)(sqlite3_file*, int);
+  int (*xCheckReservedLock)(sqlite3_file*, int *pResOut);
+  int (*xFileControl)(sqlite3_file*, int op, void *pArg);
+  int (*xSectorSize)(sqlite3_file*);
+  int (*xDeviceCharacteristics)(sqlite3_file*);
+  /* Methods above are valid for version 1 */
+  int (*xShmMap)(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
+  int (*xShmLock)(sqlite3_file*, int offset, int n, int flags);
+  void (*xShmBarrier)(sqlite3_file*);
+  int (*xShmUnmap)(sqlite3_file*, int deleteFlag);
+  /* Methods above are valid for version 2 */
+  int (*xFetch)(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
+  int (*xUnfetch)(sqlite3_file*, sqlite3_int64 iOfst, void *p);
+  /* Methods above are valid for version 3 */
+  /* Additional methods may be added in future releases */
+};
+
+/*
+** CAPI3REF: Standard File Control Opcodes
+** KEYWORDS: {file control opcodes} {file control opcode}
+**
+** These integer constants are opcodes for the xFileControl method
+** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]
+** interface.
+**
+** <ul>
+** <li>[[SQLITE_FCNTL_LOCKSTATE]]
+** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging.  This
+** opcode causes the xFileControl method to write the current state of
+** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
+** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
+** into an integer that the pArg argument points to. This capability
+** is used during testing and is only available when the SQLITE_TEST
+** compile-time option is used.
+**
+** <li>[[SQLITE_FCNTL_SIZE_HINT]]
+** The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS
+** layer a hint of how large the database file will grow to be during the
+** current transaction.  This hint is not guaranteed to be accurate but it
+** is often close.  The underlying VFS might choose to preallocate database
+** file space based on this hint in order to help writes to the database
+** file run faster.
+**
+** <li>[[SQLITE_FCNTL_CHUNK_SIZE]]
+** The [SQLITE_FCNTL_CHUNK_SIZE] opcode is used to request that the VFS
+** extends and truncates the database file in chunks of a size specified
+** by the user. The fourth argument to [sqlite3_file_control()] should 
+** point to an integer (type int) containing the new chunk-size to use
+** for the nominated database. Allocating database file space in large
+** chunks (say 1MB at a time), may reduce file-system fragmentation and
+** improve performance on some systems.
+**
+** <li>[[SQLITE_FCNTL_FILE_POINTER]]
+** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer
+** to the [sqlite3_file] object associated with a particular database
+** connection.  See also [SQLITE_FCNTL_JOURNAL_POINTER].
+**
+** <li>[[SQLITE_FCNTL_JOURNAL_POINTER]]
+** The [SQLITE_FCNTL_JOURNAL_POINTER] opcode is used to obtain a pointer
+** to the [sqlite3_file] object associated with the journal file (either
+** the [rollback journal] or the [write-ahead log]) for a particular database
+** connection.  See also [SQLITE_FCNTL_FILE_POINTER].
+**
+** <li>[[SQLITE_FCNTL_SYNC_OMITTED]]
+** No longer in use.
+**
+** <li>[[SQLITE_FCNTL_SYNC]]
+** The [SQLITE_FCNTL_SYNC] opcode is generated internally by SQLite and
+** sent to the VFS immediately before the xSync method is invoked on a
+** database file descriptor. Or, if the xSync method is not invoked 
+** because the user has configured SQLite with 
+** [PRAGMA synchronous | PRAGMA synchronous=OFF] it is invoked in place 
+** of the xSync method. In most cases, the pointer argument passed with
+** this file-control is NULL. However, if the database file is being synced
+** as part of a multi-database commit, the argument points to a nul-terminated
+** string containing the transactions master-journal file name. VFSes that 
+** do not need this signal should silently ignore this opcode. Applications 
+** should not call [sqlite3_file_control()] with this opcode as doing so may 
+** disrupt the operation of the specialized VFSes that do require it.  
+**
+** <li>[[SQLITE_FCNTL_COMMIT_PHASETWO]]
+** The [SQLITE_FCNTL_COMMIT_PHASETWO] opcode is generated internally by SQLite
+** and sent to the VFS after a transaction has been committed immediately
+** but before the database is unlocked. VFSes that do not need this signal
+** should silently ignore this opcode. Applications should not call
+** [sqlite3_file_control()] with this opcode as doing so may disrupt the 
+** operation of the specialized VFSes that do require it.  
+**
+** <li>[[SQLITE_FCNTL_WIN32_AV_RETRY]]
+** ^The [SQLITE_FCNTL_WIN32_AV_RETRY] opcode is used to configure automatic
+** retry counts and intervals for certain disk I/O operations for the
+** windows [VFS] in order to provide robustness in the presence of
+** anti-virus programs.  By default, the windows VFS will retry file read,
+** file write, and file delete operations up to 10 times, with a delay
+** of 25 milliseconds before the first retry and with the delay increasing
+** by an additional 25 milliseconds with each subsequent retry.  This
+** opcode allows these two values (10 retries and 25 milliseconds of delay)
+** to be adjusted.  The values are changed for all database connections
+** within the same process.  The argument is a pointer to an array of two
+** integers where the first integer i the new retry count and the second
+** integer is the delay.  If either integer is negative, then the setting
+** is not changed but instead the prior value of that setting is written
+** into the array entry, allowing the current retry settings to be
+** interrogated.  The zDbName parameter is ignored.
+**
+** <li>[[SQLITE_FCNTL_PERSIST_WAL]]
+** ^The [SQLITE_FCNTL_PERSIST_WAL] opcode is used to set or query the
+** persistent [WAL | Write Ahead Log] setting.  By default, the auxiliary
+** write ahead log and shared memory files used for transaction control
+** are automatically deleted when the latest connection to the database
+** closes.  Setting persistent WAL mode causes those files to persist after
+** close.  Persisting the files is useful when other processes that do not
+** have write permission on the directory containing the database file want
+** to read the database file, as the WAL and shared memory files must exist
+** in order for the database to be readable.  The fourth parameter to
+** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
+** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
+** WAL mode.  If the integer is -1, then it is overwritten with the current
+** WAL persistence setting.
+**
+** <li>[[SQLITE_FCNTL_POWERSAFE_OVERWRITE]]
+** ^The [SQLITE_FCNTL_POWERSAFE_OVERWRITE] opcode is used to set or query the
+** persistent "powersafe-overwrite" or "PSOW" setting.  The PSOW setting
+** determines the [SQLITE_IOCAP_POWERSAFE_OVERWRITE] bit of the
+** xDeviceCharacteristics methods. The fourth parameter to
+** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
+** That integer is 0 to disable zero-damage mode or 1 to enable zero-damage
+** mode.  If the integer is -1, then it is overwritten with the current
+** zero-damage mode setting.
+**
+** <li>[[SQLITE_FCNTL_OVERWRITE]]
+** ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening
+** a write transaction to indicate that, unless it is rolled back for some
+** reason, the entire database file will be overwritten by the current 
+** transaction. This is used by VACUUM operations.
+**
+** <li>[[SQLITE_FCNTL_VFSNAME]]
+** ^The [SQLITE_FCNTL_VFSNAME] opcode can be used to obtain the names of
+** all [VFSes] in the VFS stack.  The names are of all VFS shims and the
+** final bottom-level VFS are written into memory obtained from 
+** [sqlite3_malloc()] and the result is stored in the char* variable
+** that the fourth parameter of [sqlite3_file_control()] points to.
+** The caller is responsible for freeing the memory when done.  As with
+** all file-control actions, there is no guarantee that this will actually
+** do anything.  Callers should initialize the char* variable to a NULL
+** pointer in case this file-control is not implemented.  This file-control
+** is intended for diagnostic use only.
+**
+** <li>[[SQLITE_FCNTL_VFS_POINTER]]
+** ^The [SQLITE_FCNTL_VFS_POINTER] opcode finds a pointer to the top-level
+** [VFSes] currently in use.  ^(The argument X in
+** sqlite3_file_control(db,SQLITE_FCNTL_VFS_POINTER,X) must be
+** of type "[sqlite3_vfs] **".  This opcodes will set *X
+** to a pointer to the top-level VFS.)^
+** ^When there are multiple VFS shims in the stack, this opcode finds the
+** upper-most shim only.
+**
+** <li>[[SQLITE_FCNTL_PRAGMA]]
+** ^Whenever a [PRAGMA] statement is parsed, an [SQLITE_FCNTL_PRAGMA] 
+** file control is sent to the open [sqlite3_file] object corresponding
+** to the database file to which the pragma statement refers. ^The argument
+** to the [SQLITE_FCNTL_PRAGMA] file control is an array of
+** pointers to strings (char**) in which the second element of the array
+** is the name of the pragma and the third element is the argument to the
+** pragma or NULL if the pragma has no argument.  ^The handler for an
+** [SQLITE_FCNTL_PRAGMA] file control can optionally make the first element
+** of the char** argument point to a string obtained from [sqlite3_mprintf()]
+** or the equivalent and that string will become the result of the pragma or
+** the error message if the pragma fails. ^If the
+** [SQLITE_FCNTL_PRAGMA] file control returns [SQLITE_NOTFOUND], then normal 
+** [PRAGMA] processing continues.  ^If the [SQLITE_FCNTL_PRAGMA]
+** file control returns [SQLITE_OK], then the parser assumes that the
+** VFS has handled the PRAGMA itself and the parser generates a no-op
+** prepared statement if result string is NULL, or that returns a copy
+** of the result string if the string is non-NULL.
+** ^If the [SQLITE_FCNTL_PRAGMA] file control returns
+** any result code other than [SQLITE_OK] or [SQLITE_NOTFOUND], that means
+** that the VFS encountered an error while handling the [PRAGMA] and the
+** compilation of the PRAGMA fails with an error.  ^The [SQLITE_FCNTL_PRAGMA]
+** file control occurs at the beginning of pragma statement analysis and so
+** it is able to override built-in [PRAGMA] statements.
+**
+** <li>[[SQLITE_FCNTL_BUSYHANDLER]]
+** ^The [SQLITE_FCNTL_BUSYHANDLER]
+** file-control may be invoked by SQLite on the database file handle
+** shortly after it is opened in order to provide a custom VFS with access
+** to the connections busy-handler callback. The argument is of type (void **)
+** - an array of two (void *) values. The first (void *) actually points
+** to a function of type (int (*)(void *)). In order to invoke the connections
+** busy-handler, this function should be invoked with the second (void *) in
+** the array as the only argument. If it returns non-zero, then the operation
+** should be retried. If it returns zero, the custom VFS should abandon the
+** current operation.
+**
+** <li>[[SQLITE_FCNTL_TEMPFILENAME]]
+** ^Application can invoke the [SQLITE_FCNTL_TEMPFILENAME] file-control
+** to have SQLite generate a
+** temporary filename using the same algorithm that is followed to generate
+** temporary filenames for TEMP tables and other internal uses.  The
+** argument should be a char** which will be filled with the filename
+** written into memory obtained from [sqlite3_malloc()].  The caller should
+** invoke [sqlite3_free()] on the result to avoid a memory leak.
+**
+** <li>[[SQLITE_FCNTL_MMAP_SIZE]]
+** The [SQLITE_FCNTL_MMAP_SIZE] file control is used to query or set the
+** maximum number of bytes that will be used for memory-mapped I/O.
+** The argument is a pointer to a value of type sqlite3_int64 that
+** is an advisory maximum number of bytes in the file to memory map.  The
+** pointer is overwritten with the old value.  The limit is not changed if
+** the value originally pointed to is negative, and so the current limit 
+** can be queried by passing in a pointer to a negative number.  This
+** file-control is used internally to implement [PRAGMA mmap_size].
+**
+** <li>[[SQLITE_FCNTL_TRACE]]
+** The [SQLITE_FCNTL_TRACE] file control provides advisory information
+** to the VFS about what the higher layers of the SQLite stack are doing.
+** This file control is used by some VFS activity tracing [shims].
+** The argument is a zero-terminated string.  Higher layers in the
+** SQLite stack may generate instances of this file control if
+** the [SQLITE_USE_FCNTL_TRACE] compile-time option is enabled.
+**
+** <li>[[SQLITE_FCNTL_HAS_MOVED]]
+** The [SQLITE_FCNTL_HAS_MOVED] file control interprets its argument as a
+** pointer to an integer and it writes a boolean into that integer depending
+** on whether or not the file has been renamed, moved, or deleted since it
+** was first opened.
+**
+** <li>[[SQLITE_FCNTL_WIN32_GET_HANDLE]]
+** The [SQLITE_FCNTL_WIN32_GET_HANDLE] opcode can be used to obtain the
+** underlying native file handle associated with a file handle.  This file
+** control interprets its argument as a pointer to a native file handle and
+** writes the resulting value there.
+**
+** <li>[[SQLITE_FCNTL_WIN32_SET_HANDLE]]
+** The [SQLITE_FCNTL_WIN32_SET_HANDLE] opcode is used for debugging.  This
+** opcode causes the xFileControl method to swap the file handle with the one
+** pointed to by the pArg argument.  This capability is used during testing
+** and only needs to be supported when SQLITE_TEST is defined.
+**
+** <li>[[SQLITE_FCNTL_WAL_BLOCK]]
+** The [SQLITE_FCNTL_WAL_BLOCK] is a signal to the VFS layer that it might
+** be advantageous to block on the next WAL lock if the lock is not immediately
+** available.  The WAL subsystem issues this signal during rare
+** circumstances in order to fix a problem with priority inversion.
+** Applications should <em>not</em> use this file-control.
+**
+** <li>[[SQLITE_FCNTL_ZIPVFS]]
+** The [SQLITE_FCNTL_ZIPVFS] opcode is implemented by zipvfs only. All other
+** VFS should return SQLITE_NOTFOUND for this opcode.
+**
+** <li>[[SQLITE_FCNTL_RBU]]
+** The [SQLITE_FCNTL_RBU] opcode is implemented by the special VFS used by
+** the RBU extension only.  All other VFS should return SQLITE_NOTFOUND for
+** this opcode.  
+** </ul>
+*/
+#define SQLITE_FCNTL_LOCKSTATE               1
+#define SQLITE_FCNTL_GET_LOCKPROXYFILE       2
+#define SQLITE_FCNTL_SET_LOCKPROXYFILE       3
+#define SQLITE_FCNTL_LAST_ERRNO              4
+#define SQLITE_FCNTL_SIZE_HINT               5
+#define SQLITE_FCNTL_CHUNK_SIZE              6
+#define SQLITE_FCNTL_FILE_POINTER            7
+#define SQLITE_FCNTL_SYNC_OMITTED            8
+#define SQLITE_FCNTL_WIN32_AV_RETRY          9
+#define SQLITE_FCNTL_PERSIST_WAL            10
+#define SQLITE_FCNTL_OVERWRITE              11
+#define SQLITE_FCNTL_VFSNAME                12
+#define SQLITE_FCNTL_POWERSAFE_OVERWRITE    13
+#define SQLITE_FCNTL_PRAGMA                 14
+#define SQLITE_FCNTL_BUSYHANDLER            15
+#define SQLITE_FCNTL_TEMPFILENAME           16
+#define SQLITE_FCNTL_MMAP_SIZE              18
+#define SQLITE_FCNTL_TRACE                  19
+#define SQLITE_FCNTL_HAS_MOVED              20
+#define SQLITE_FCNTL_SYNC                   21
+#define SQLITE_FCNTL_COMMIT_PHASETWO        22
+#define SQLITE_FCNTL_WIN32_SET_HANDLE       23
+#define SQLITE_FCNTL_WAL_BLOCK              24
+#define SQLITE_FCNTL_ZIPVFS                 25
+#define SQLITE_FCNTL_RBU                    26
+#define SQLITE_FCNTL_VFS_POINTER            27
+#define SQLITE_FCNTL_JOURNAL_POINTER        28
+#define SQLITE_FCNTL_WIN32_GET_HANDLE       29
+
+/* deprecated names */
+#define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
+#define SQLITE_SET_LOCKPROXYFILE      SQLITE_FCNTL_SET_LOCKPROXYFILE
+#define SQLITE_LAST_ERRNO             SQLITE_FCNTL_LAST_ERRNO
+
+
+/*
+** CAPI3REF: Mutex Handle
+**
+** The mutex module within SQLite defines [sqlite3_mutex] to be an
+** abstract type for a mutex object.  The SQLite core never looks
+** at the internal representation of an [sqlite3_mutex].  It only
+** deals with pointers to the [sqlite3_mutex] object.
+**
+** Mutexes are created using [sqlite3_mutex_alloc()].
+*/
+typedef struct sqlite3_mutex sqlite3_mutex;
+
+/*
+** CAPI3REF: Loadable Extension Thunk
+**
+** A pointer to the opaque sqlite3_api_routines structure is passed as
+** the third parameter to entry points of [loadable extensions].  This
+** structure must be typedefed in order to work around compiler warnings
+** on some platforms.
+*/
+typedef struct sqlite3_api_routines sqlite3_api_routines;
+
+/*
+** CAPI3REF: OS Interface Object
+**
+** An instance of the sqlite3_vfs object defines the interface between
+** the SQLite core and the underlying operating system.  The "vfs"
+** in the name of the object stands for "virtual file system".  See
+** the [VFS | VFS documentation] for further information.
+**
+** The value of the iVersion field is initially 1 but may be larger in
+** future versions of SQLite.  Additional fields may be appended to this
+** object when the iVersion value is increased.  Note that the structure
+** of the sqlite3_vfs object changes in the transaction between
+** SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not
+** modified.
+**
+** The szOsFile field is the size of the subclassed [sqlite3_file]
+** structure used by this VFS.  mxPathname is the maximum length of
+** a pathname in this VFS.
+**
+** Registered sqlite3_vfs objects are kept on a linked list formed by
+** the pNext pointer.  The [sqlite3_vfs_register()]
+** and [sqlite3_vfs_unregister()] interfaces manage this list
+** in a thread-safe way.  The [sqlite3_vfs_find()] interface
+** searches the list.  Neither the application code nor the VFS
+** implementation should use the pNext pointer.
+**
+** The pNext field is the only field in the sqlite3_vfs
+** structure that SQLite will ever modify.  SQLite will only access
+** or modify this field while holding a particular static mutex.
+** The application should never modify anything within the sqlite3_vfs
+** object once the object has been registered.
+**
+** The zName field holds the name of the VFS module.  The name must
+** be unique across all VFS modules.
+**
+** [[sqlite3_vfs.xOpen]]
+** ^SQLite guarantees that the zFilename parameter to xOpen
+** is either a NULL pointer or string obtained
+** from xFullPathname() with an optional suffix added.
+** ^If a suffix is added to the zFilename parameter, it will
+** consist of a single "-" character followed by no more than
+** 11 alphanumeric and/or "-" characters.
+** ^SQLite further guarantees that
+** the string will be valid and unchanged until xClose() is
+** called. Because of the previous sentence,
+** the [sqlite3_file] can safely store a pointer to the
+** filename if it needs to remember the filename for some reason.
+** If the zFilename parameter to xOpen is a NULL pointer then xOpen
+** must invent its own temporary name for the file.  ^Whenever the 
+** xFilename parameter is NULL it will also be the case that the
+** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].
+**
+** The flags argument to xOpen() includes all bits set in
+** the flags argument to [sqlite3_open_v2()].  Or if [sqlite3_open()]
+** or [sqlite3_open16()] is used, then flags includes at least
+** [SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]. 
+** If xOpen() opens a file read-only then it sets *pOutFlags to
+** include [SQLITE_OPEN_READONLY].  Other bits in *pOutFlags may be set.
+**
+** ^(SQLite will also add one of the following flags to the xOpen()
+** call, depending on the object being opened:
+**
+** <ul>
+** <li>  [SQLITE_OPEN_MAIN_DB]
+** <li>  [SQLITE_OPEN_MAIN_JOURNAL]
+** <li>  [SQLITE_OPEN_TEMP_DB]
+** <li>  [SQLITE_OPEN_TEMP_JOURNAL]
+** <li>  [SQLITE_OPEN_TRANSIENT_DB]
+** <li>  [SQLITE_OPEN_SUBJOURNAL]
+** <li>  [SQLITE_OPEN_MASTER_JOURNAL]
+** <li>  [SQLITE_OPEN_WAL]
+** </ul>)^
+**
+** The file I/O implementation can use the object type flags to
+** change the way it deals with files.  For example, an application
+** that does not care about crash recovery or rollback might make
+** the open of a journal file a no-op.  Writes to this journal would
+** also be no-ops, and any attempt to read the journal would return
+** SQLITE_IOERR.  Or the implementation might recognize that a database
+** file will be doing page-aligned sector reads and writes in a random
+** order and set up its I/O subsystem accordingly.
+**
+** SQLite might also add one of the following flags to the xOpen method:
+**
+** <ul>
+** <li> [SQLITE_OPEN_DELETEONCLOSE]
+** <li> [SQLITE_OPEN_EXCLUSIVE]
+** </ul>
+**
+** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
+** deleted when it is closed.  ^The [SQLITE_OPEN_DELETEONCLOSE]
+** will be set for TEMP databases and their journals, transient
+** databases, and subjournals.
+**
+** ^The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction
+** with the [SQLITE_OPEN_CREATE] flag, which are both directly
+** analogous to the O_EXCL and O_CREAT flags of the POSIX open()
+** API.  The SQLITE_OPEN_EXCLUSIVE flag, when paired with the 
+** SQLITE_OPEN_CREATE, is used to indicate that file should always
+** be created, and that it is an error if it already exists.
+** It is <i>not</i> used to indicate the file should be opened 
+** for exclusive access.
+**
+** ^At least szOsFile bytes of memory are allocated by SQLite
+** to hold the  [sqlite3_file] structure passed as the third
+** argument to xOpen.  The xOpen method does not have to
+** allocate the structure; it should just fill it in.  Note that
+** the xOpen method must set the sqlite3_file.pMethods to either
+** a valid [sqlite3_io_methods] object or to NULL.  xOpen must do
+** this even if the open fails.  SQLite expects that the sqlite3_file.pMethods
+** element will be valid after xOpen returns regardless of the success
+** or failure of the xOpen call.
+**
+** [[sqlite3_vfs.xAccess]]
+** ^The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]
+** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to
+** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]
+** to test whether a file is at least readable.   The file can be a
+** directory.
+**
+** ^SQLite will always allocate at least mxPathname+1 bytes for the
+** output buffer xFullPathname.  The exact size of the output buffer
+** is also passed as a parameter to both  methods. If the output buffer
+** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is
+** handled as a fatal error by SQLite, vfs implementations should endeavor
+** to prevent this by setting mxPathname to a sufficiently large value.
+**
+** The xRandomness(), xSleep(), xCurrentTime(), and xCurrentTimeInt64()
+** interfaces are not strictly a part of the filesystem, but they are
+** included in the VFS structure for completeness.
+** The xRandomness() function attempts to return nBytes bytes
+** of good-quality randomness into zOut.  The return value is
+** the actual number of bytes of randomness obtained.
+** The xSleep() method causes the calling thread to sleep for at
+** least the number of microseconds given.  ^The xCurrentTime()
+** method returns a Julian Day Number for the current date and time as
+** a floating point value.
+** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
+** Day Number multiplied by 86400000 (the number of milliseconds in 
+** a 24-hour day).  
+** ^SQLite will use the xCurrentTimeInt64() method to get the current
+** date and time if that method is available (if iVersion is 2 or 
+** greater and the function pointer is not NULL) and will fall back
+** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
+**
+** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
+** are not used by the SQLite core.  These optional interfaces are provided
+** by some VFSes to facilitate testing of the VFS code. By overriding 
+** system calls with functions under its control, a test program can
+** simulate faults and error conditions that would otherwise be difficult
+** or impossible to induce.  The set of system calls that can be overridden
+** varies from one VFS to another, and from one version of the same VFS to the
+** next.  Applications that use these interfaces must be prepared for any
+** or all of these interfaces to be NULL or for their behavior to change
+** from one release to the next.  Applications must not attempt to access
+** any of these methods if the iVersion of the VFS is less than 3.
+*/
+typedef struct sqlite3_vfs sqlite3_vfs;
+typedef void (*sqlite3_syscall_ptr)(void);
+struct sqlite3_vfs {
+  int iVersion;            /* Structure version number (currently 3) */
+  int szOsFile;            /* Size of subclassed sqlite3_file */
+  int mxPathname;          /* Maximum file pathname length */
+  sqlite3_vfs *pNext;      /* Next registered VFS */
+  const char *zName;       /* Name of this virtual file system */
+  void *pAppData;          /* Pointer to application-specific data */
+  int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
+               int flags, int *pOutFlags);
+  int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
+  int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut);
+  int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
+  void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
+  void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
+  void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void);
+  void (*xDlClose)(sqlite3_vfs*, void*);
+  int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
+  int (*xSleep)(sqlite3_vfs*, int microseconds);
+  int (*xCurrentTime)(sqlite3_vfs*, double*);
+  int (*xGetLastError)(sqlite3_vfs*, int, char *);
+  /*
+  ** The methods above are in version 1 of the sqlite_vfs object
+  ** definition.  Those that follow are added in version 2 or later
+  */
+  int (*xCurrentTimeInt64)(sqlite3_vfs*, sqlite3_int64*);
+  /*
+  ** The methods above are in versions 1 and 2 of the sqlite_vfs object.
+  ** Those below are for version 3 and greater.
+  */
+  int (*xSetSystemCall)(sqlite3_vfs*, const char *zName, sqlite3_syscall_ptr);
+  sqlite3_syscall_ptr (*xGetSystemCall)(sqlite3_vfs*, const char *zName);
+  const char *(*xNextSystemCall)(sqlite3_vfs*, const char *zName);
+  /*
+  ** The methods above are in versions 1 through 3 of the sqlite_vfs object.
+  ** New fields may be appended in future versions.  The iVersion
+  ** value will increment whenever this happens. 
+  */
+};
+
+/*
+** CAPI3REF: Flags for the xAccess VFS method
+**
+** These integer constants can be used as the third parameter to
+** the xAccess method of an [sqlite3_vfs] object.  They determine
+** what kind of permissions the xAccess method is looking for.
+** With SQLITE_ACCESS_EXISTS, the xAccess method
+** simply checks whether the file exists.
+** With SQLITE_ACCESS_READWRITE, the xAccess method
+** checks whether the named directory is both readable and writable
+** (in other words, if files can be added, removed, and renamed within
+** the directory).
+** The SQLITE_ACCESS_READWRITE constant is currently used only by the
+** [temp_store_directory pragma], though this could change in a future
+** release of SQLite.
+** With SQLITE_ACCESS_READ, the xAccess method
+** checks whether the file is readable.  The SQLITE_ACCESS_READ constant is
+** currently unused, though it might be used in a future release of
+** SQLite.
+*/
+#define SQLITE_ACCESS_EXISTS    0
+#define SQLITE_ACCESS_READWRITE 1   /* Used by PRAGMA temp_store_directory */
+#define SQLITE_ACCESS_READ      2   /* Unused */
+
+/*
+** CAPI3REF: Flags for the xShmLock VFS method
+**
+** These integer constants define the various locking operations
+** allowed by the xShmLock method of [sqlite3_io_methods].  The
+** following are the only legal combinations of flags to the
+** xShmLock method:
+**
+** <ul>
+** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_SHARED
+** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE
+** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED
+** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE
+** </ul>
+**
+** When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as
+** was given on the corresponding lock.  
+**
+** The xShmLock method can transition between unlocked and SHARED or
+** between unlocked and EXCLUSIVE.  It cannot transition between SHARED
+** and EXCLUSIVE.
+*/
+#define SQLITE_SHM_UNLOCK       1
+#define SQLITE_SHM_LOCK         2
+#define SQLITE_SHM_SHARED       4
+#define SQLITE_SHM_EXCLUSIVE    8
+
+/*
+** CAPI3REF: Maximum xShmLock index
+**
+** The xShmLock method on [sqlite3_io_methods] may use values
+** between 0 and this upper bound as its "offset" argument.
+** The SQLite core will never attempt to acquire or release a
+** lock outside of this range
+*/
+#define SQLITE_SHM_NLOCK        8
+
+
+/*
+** CAPI3REF: Initialize The SQLite Library
+**
+** ^The sqlite3_initialize() routine initializes the
+** SQLite library.  ^The sqlite3_shutdown() routine
+** deallocates any resources that were allocated by sqlite3_initialize().
+** These routines are designed to aid in process initialization and
+** shutdown on embedded systems.  Workstation applications using
+** SQLite normally do not need to invoke either of these routines.
+**
+** A call to sqlite3_initialize() is an "effective" call if it is
+** the first time sqlite3_initialize() is invoked during the lifetime of
+** the process, or if it is the first time sqlite3_initialize() is invoked
+** following a call to sqlite3_shutdown().  ^(Only an effective call
+** of sqlite3_initialize() does any initialization.  All other calls
+** are harmless no-ops.)^
+**
+** A call to sqlite3_shutdown() is an "effective" call if it is the first
+** call to sqlite3_shutdown() since the last sqlite3_initialize().  ^(Only
+** an effective call to sqlite3_shutdown() does any deinitialization.
+** All other valid calls to sqlite3_shutdown() are harmless no-ops.)^
+**
+** The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown()
+** is not.  The sqlite3_shutdown() interface must only be called from a
+** single thread.  All open [database connections] must be closed and all
+** other SQLite resources must be deallocated prior to invoking
+** sqlite3_shutdown().
+**
+** Among other things, ^sqlite3_initialize() will invoke
+** sqlite3_os_init().  Similarly, ^sqlite3_shutdown()
+** will invoke sqlite3_os_end().
+**
+** ^The sqlite3_initialize() routine returns [SQLITE_OK] on success.
+** ^If for some reason, sqlite3_initialize() is unable to initialize
+** the library (perhaps it is unable to allocate a needed resource such
+** as a mutex) it returns an [error code] other than [SQLITE_OK].
+**
+** ^The sqlite3_initialize() routine is called internally by many other
+** SQLite interfaces so that an application usually does not need to
+** invoke sqlite3_initialize() directly.  For example, [sqlite3_open()]
+** calls sqlite3_initialize() so the SQLite library will be automatically
+** initialized when [sqlite3_open()] is called if it has not be initialized
+** already.  ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]
+** compile-time option, then the automatic calls to sqlite3_initialize()
+** are omitted and the application must call sqlite3_initialize() directly
+** prior to using any other SQLite interface.  For maximum portability,
+** it is recommended that applications always invoke sqlite3_initialize()
+** directly prior to using any other SQLite interface.  Future releases
+** of SQLite may require this.  In other words, the behavior exhibited
+** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the
+** default behavior in some future release of SQLite.
+**
+** The sqlite3_os_init() routine does operating-system specific
+** initialization of the SQLite library.  The sqlite3_os_end()
+** routine undoes the effect of sqlite3_os_init().  Typical tasks
+** performed by these routines include allocation or deallocation
+** of static resources, initialization of global variables,
+** setting up a default [sqlite3_vfs] module, or setting up
+** a default configuration using [sqlite3_config()].
+**
+** The application should never invoke either sqlite3_os_init()
+** or sqlite3_os_end() directly.  The application should only invoke
+** sqlite3_initialize() and sqlite3_shutdown().  The sqlite3_os_init()
+** interface is called automatically by sqlite3_initialize() and
+** sqlite3_os_end() is called by sqlite3_shutdown().  Appropriate
+** implementations for sqlite3_os_init() and sqlite3_os_end()
+** are built into SQLite when it is compiled for Unix, Windows, or OS/2.
+** When [custom builds | built for other platforms]
+** (using the [SQLITE_OS_OTHER=1] compile-time
+** option) the application must supply a suitable implementation for
+** sqlite3_os_init() and sqlite3_os_end().  An application-supplied
+** implementation of sqlite3_os_init() or sqlite3_os_end()
+** must return [SQLITE_OK] on success and some other [error code] upon
+** failure.
+*/
+SQLITE_API int sqlite3_initialize(void);
+SQLITE_API int sqlite3_shutdown(void);
+SQLITE_API int sqlite3_os_init(void);
+SQLITE_API int sqlite3_os_end(void);
+
+/*
+** CAPI3REF: Configuring The SQLite Library
+**
+** The sqlite3_config() interface is used to make global configuration
+** changes to SQLite in order to tune SQLite to the specific needs of
+** the application.  The default configuration is recommended for most
+** applications and so this routine is usually not necessary.  It is
+** provided to support rare applications with unusual needs.
+**
+** <b>The sqlite3_config() interface is not threadsafe. The application
+** must ensure that no other SQLite interfaces are invoked by other
+** threads while sqlite3_config() is running.</b>
+**
+** The sqlite3_config() interface
+** may only be invoked prior to library initialization using
+** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
+** ^If sqlite3_config() is called after [sqlite3_initialize()] and before
+** [sqlite3_shutdown()] then it will return SQLITE_MISUSE.
+** Note, however, that ^sqlite3_config() can be called as part of the
+** implementation of an application-defined [sqlite3_os_init()].
+**
+** The first argument to sqlite3_config() is an integer
+** [configuration option] that determines
+** what property of SQLite is to be configured.  Subsequent arguments
+** vary depending on the [configuration option]
+** in the first argument.
+**
+** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
+** ^If the option is unknown or SQLite is unable to set the option
+** then this routine returns a non-zero [error code].
+*/
+SQLITE_API int sqlite3_config(int, ...);
+
+/*
+** CAPI3REF: Configure database connections
+** METHOD: sqlite3
+**
+** The sqlite3_db_config() interface is used to make configuration
+** changes to a [database connection].  The interface is similar to
+** [sqlite3_config()] except that the changes apply to a single
+** [database connection] (specified in the first argument).
+**
+** The second argument to sqlite3_db_config(D,V,...)  is the
+** [SQLITE_DBCONFIG_LOOKASIDE | configuration verb] - an integer code 
+** that indicates what aspect of the [database connection] is being configured.
+** Subsequent arguments vary depending on the configuration verb.
+**
+** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
+** the call is considered successful.
+*/
+SQLITE_API int sqlite3_db_config(sqlite3*, int op, ...);
+
+/*
+** CAPI3REF: Memory Allocation Routines
+**
+** An instance of this object defines the interface between SQLite
+** and low-level memory allocation routines.
+**
+** This object is used in only one place in the SQLite interface.
+** A pointer to an instance of this object is the argument to
+** [sqlite3_config()] when the configuration option is
+** [SQLITE_CONFIG_MALLOC] or [SQLITE_CONFIG_GETMALLOC].  
+** By creating an instance of this object
+** and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC])
+** during configuration, an application can specify an alternative
+** memory allocation subsystem for SQLite to use for all of its
+** dynamic memory needs.
+**
+** Note that SQLite comes with several [built-in memory allocators]
+** that are perfectly adequate for the overwhelming majority of applications
+** and that this object is only useful to a tiny minority of applications
+** with specialized memory allocation requirements.  This object is
+** also used during testing of SQLite in order to specify an alternative
+** memory allocator that simulates memory out-of-memory conditions in
+** order to verify that SQLite recovers gracefully from such
+** conditions.
+**
+** The xMalloc, xRealloc, and xFree methods must work like the
+** malloc(), realloc() and free() functions from the standard C library.
+** ^SQLite guarantees that the second argument to
+** xRealloc is always a value returned by a prior call to xRoundup.
+**
+** xSize should return the allocated size of a memory allocation
+** previously obtained from xMalloc or xRealloc.  The allocated size
+** is always at least as big as the requested size but may be larger.
+**
+** The xRoundup method returns what would be the allocated size of
+** a memory allocation given a particular requested size.  Most memory
+** allocators round up memory allocations at least to the next multiple
+** of 8.  Some allocators round up to a larger multiple or to a power of 2.
+** Every memory allocation request coming in through [sqlite3_malloc()]
+** or [sqlite3_realloc()] first calls xRoundup.  If xRoundup returns 0, 
+** that causes the corresponding memory allocation to fail.
+**
+** The xInit method initializes the memory allocator.  For example,
+** it might allocate any require mutexes or initialize internal data
+** structures.  The xShutdown method is invoked (indirectly) by
+** [sqlite3_shutdown()] and should deallocate any resources acquired
+** by xInit.  The pAppData pointer is used as the only parameter to
+** xInit and xShutdown.
+**
+** SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes
+** the xInit method, so the xInit method need not be threadsafe.  The
+** xShutdown method is only called from [sqlite3_shutdown()] so it does
+** not need to be threadsafe either.  For all other methods, SQLite
+** holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the
+** [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which
+** it is by default) and so the methods are automatically serialized.
+** However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other
+** methods must be threadsafe or else make their own arrangements for
+** serialization.
+**
+** SQLite will never invoke xInit() more than once without an intervening
+** call to xShutdown().
+*/
+typedef struct sqlite3_mem_methods sqlite3_mem_methods;
+struct sqlite3_mem_methods {
+  void *(*xMalloc)(int);         /* Memory allocation function */
+  void (*xFree)(void*);          /* Free a prior allocation */
+  void *(*xRealloc)(void*,int);  /* Resize an allocation */
+  int (*xSize)(void*);           /* Return the size of an allocation */
+  int (*xRoundup)(int);          /* Round up request size to allocation size */
+  int (*xInit)(void*);           /* Initialize the memory allocator */
+  void (*xShutdown)(void*);      /* Deinitialize the memory allocator */
+  void *pAppData;                /* Argument to xInit() and xShutdown() */
+};
+
+/*
+** CAPI3REF: Configuration Options
+** KEYWORDS: {configuration option}
+**
+** These constants are the available integer configuration options that
+** can be passed as the first argument to the [sqlite3_config()] interface.
+**
+** New configuration options may be added in future releases of SQLite.
+** Existing configuration options might be discontinued.  Applications
+** should check the return code from [sqlite3_config()] to make sure that
+** the call worked.  The [sqlite3_config()] interface will return a
+** non-zero [error code] if a discontinued or unsupported configuration option
+** is invoked.
+**
+** <dl>
+** [[SQLITE_CONFIG_SINGLETHREAD]] <dt>SQLITE_CONFIG_SINGLETHREAD</dt>
+** <dd>There are no arguments to this option.  ^This option sets the
+** [threading mode] to Single-thread.  In other words, it disables
+** all mutexing and puts SQLite into a mode where it can only be used
+** by a single thread.   ^If SQLite is compiled with
+** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
+** it is not possible to change the [threading mode] from its default
+** value of Single-thread and so [sqlite3_config()] will return 
+** [SQLITE_ERROR] if called with the SQLITE_CONFIG_SINGLETHREAD
+** configuration option.</dd>
+**
+** [[SQLITE_CONFIG_MULTITHREAD]] <dt>SQLITE_CONFIG_MULTITHREAD</dt>
+** <dd>There are no arguments to this option.  ^This option sets the
+** [threading mode] to Multi-thread.  In other words, it disables
+** mutexing on [database connection] and [prepared statement] objects.
+** The application is responsible for serializing access to
+** [database connections] and [prepared statements].  But other mutexes
+** are enabled so that SQLite will be safe to use in a multi-threaded
+** environment as long as no two threads attempt to use the same
+** [database connection] at the same time.  ^If SQLite is compiled with
+** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
+** it is not possible to set the Multi-thread [threading mode] and
+** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
+** SQLITE_CONFIG_MULTITHREAD configuration option.</dd>
+**
+** [[SQLITE_CONFIG_SERIALIZED]] <dt>SQLITE_CONFIG_SERIALIZED</dt>
+** <dd>There are no arguments to this option.  ^This option sets the
+** [threading mode] to Serialized. In other words, this option enables
+** all mutexes including the recursive
+** mutexes on [database connection] and [prepared statement] objects.
+** In this mode (which is the default when SQLite is compiled with
+** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access
+** to [database connections] and [prepared statements] so that the
+** application is free to use the same [database connection] or the
+** same [prepared statement] in different threads at the same time.
+** ^If SQLite is compiled with
+** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
+** it is not possible to set the Serialized [threading mode] and
+** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
+** SQLITE_CONFIG_SERIALIZED configuration option.</dd>
+**
+** [[SQLITE_CONFIG_MALLOC]] <dt>SQLITE_CONFIG_MALLOC</dt>
+** <dd> ^(The SQLITE_CONFIG_MALLOC option takes a single argument which is 
+** a pointer to an instance of the [sqlite3_mem_methods] structure.
+** The argument specifies
+** alternative low-level memory allocation routines to be used in place of
+** the memory allocation routines built into SQLite.)^ ^SQLite makes
+** its own private copy of the content of the [sqlite3_mem_methods] structure
+** before the [sqlite3_config()] call returns.</dd>
+**
+** [[SQLITE_CONFIG_GETMALLOC]] <dt>SQLITE_CONFIG_GETMALLOC</dt>
+** <dd> ^(The SQLITE_CONFIG_GETMALLOC option takes a single argument which
+** is a pointer to an instance of the [sqlite3_mem_methods] structure.
+** The [sqlite3_mem_methods]
+** structure is filled with the currently defined memory allocation routines.)^
+** This option can be used to overload the default memory allocation
+** routines with a wrapper that simulations memory allocation failure or
+** tracks memory usage, for example. </dd>
+**
+** [[SQLITE_CONFIG_MEMSTATUS]] <dt>SQLITE_CONFIG_MEMSTATUS</dt>
+** <dd> ^The SQLITE_CONFIG_MEMSTATUS option takes single argument of type int,
+** interpreted as a boolean, which enables or disables the collection of
+** memory allocation statistics. ^(When memory allocation statistics are
+** disabled, the following SQLite interfaces become non-operational:
+**   <ul>
+**   <li> [sqlite3_memory_used()]
+**   <li> [sqlite3_memory_highwater()]
+**   <li> [sqlite3_soft_heap_limit64()]
+**   <li> [sqlite3_status64()]
+**   </ul>)^
+** ^Memory allocation statistics are enabled by default unless SQLite is
+** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
+** allocation statistics are disabled by default.
+** </dd>
+**
+** [[SQLITE_CONFIG_SCRATCH]] <dt>SQLITE_CONFIG_SCRATCH</dt>
+** <dd> ^The SQLITE_CONFIG_SCRATCH option specifies a static memory buffer
+** that SQLite can use for scratch memory.  ^(There are three arguments
+** to SQLITE_CONFIG_SCRATCH:  A pointer an 8-byte
+** aligned memory buffer from which the scratch allocations will be
+** drawn, the size of each scratch allocation (sz),
+** and the maximum number of scratch allocations (N).)^
+** The first argument must be a pointer to an 8-byte aligned buffer
+** of at least sz*N bytes of memory.
+** ^SQLite will not use more than one scratch buffers per thread.
+** ^SQLite will never request a scratch buffer that is more than 6
+** times the database page size.
+** ^If SQLite needs needs additional
+** scratch memory beyond what is provided by this configuration option, then 
+** [sqlite3_malloc()] will be used to obtain the memory needed.<p>
+** ^When the application provides any amount of scratch memory using
+** SQLITE_CONFIG_SCRATCH, SQLite avoids unnecessary large
+** [sqlite3_malloc|heap allocations].
+** This can help [Robson proof|prevent memory allocation failures] due to heap
+** fragmentation in low-memory embedded systems.
+** </dd>
+**
+** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>
+** <dd> ^The SQLITE_CONFIG_PAGECACHE option specifies a memory pool
+** that SQLite can use for the database page cache with the default page
+** cache implementation.  
+** This configuration option is a no-op if an application-define page
+** cache implementation is loaded using the [SQLITE_CONFIG_PCACHE2].
+** ^There are three arguments to SQLITE_CONFIG_PAGECACHE: A pointer to
+** 8-byte aligned memory (pMem), the size of each page cache line (sz),
+** and the number of cache lines (N).
+** The sz argument should be the size of the largest database page
+** (a power of two between 512 and 65536) plus some extra bytes for each
+** page header.  ^The number of extra bytes needed by the page header
+** can be determined using [SQLITE_CONFIG_PCACHE_HDRSZ].
+** ^It is harmless, apart from the wasted memory,
+** for the sz parameter to be larger than necessary.  The pMem
+** argument must be either a NULL pointer or a pointer to an 8-byte
+** aligned block of memory of at least sz*N bytes, otherwise
+** subsequent behavior is undefined.
+** ^When pMem is not NULL, SQLite will strive to use the memory provided
+** to satisfy page cache needs, falling back to [sqlite3_malloc()] if
+** a page cache line is larger than sz bytes or if all of the pMem buffer
+** is exhausted.
+** ^If pMem is NULL and N is non-zero, then each database connection
+** does an initial bulk allocation for page cache memory
+** from [sqlite3_malloc()] sufficient for N cache lines if N is positive or
+** of -1024*N bytes if N is negative, . ^If additional
+** page cache memory is needed beyond what is provided by the initial
+** allocation, then SQLite goes to [sqlite3_malloc()] separately for each
+** additional cache line. </dd>
+**
+** [[SQLITE_CONFIG_HEAP]] <dt>SQLITE_CONFIG_HEAP</dt>
+** <dd> ^The SQLITE_CONFIG_HEAP option specifies a static memory buffer 
+** that SQLite will use for all of its dynamic memory allocation needs
+** beyond those provided for by [SQLITE_CONFIG_SCRATCH] and
+** [SQLITE_CONFIG_PAGECACHE].
+** ^The SQLITE_CONFIG_HEAP option is only available if SQLite is compiled
+** with either [SQLITE_ENABLE_MEMSYS3] or [SQLITE_ENABLE_MEMSYS5] and returns
+** [SQLITE_ERROR] if invoked otherwise.
+** ^There are three arguments to SQLITE_CONFIG_HEAP:
+** An 8-byte aligned pointer to the memory,
+** the number of bytes in the memory buffer, and the minimum allocation size.
+** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
+** to using its default memory allocator (the system malloc() implementation),
+** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
+** memory pointer is not NULL then the alternative memory
+** allocator is engaged to handle all of SQLites memory allocation needs.
+** The first pointer (the memory pointer) must be aligned to an 8-byte
+** boundary or subsequent behavior of SQLite will be undefined.
+** The minimum allocation size is capped at 2**12. Reasonable values
+** for the minimum allocation size are 2**5 through 2**8.</dd>
+**
+** [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt>
+** <dd> ^(The SQLITE_CONFIG_MUTEX option takes a single argument which is a
+** pointer to an instance of the [sqlite3_mutex_methods] structure.
+** The argument specifies alternative low-level mutex routines to be used
+** in place the mutex routines built into SQLite.)^  ^SQLite makes a copy of
+** the content of the [sqlite3_mutex_methods] structure before the call to
+** [sqlite3_config()] returns. ^If SQLite is compiled with
+** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
+** the entire mutexing subsystem is omitted from the build and hence calls to
+** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will
+** return [SQLITE_ERROR].</dd>
+**
+** [[SQLITE_CONFIG_GETMUTEX]] <dt>SQLITE_CONFIG_GETMUTEX</dt>
+** <dd> ^(The SQLITE_CONFIG_GETMUTEX option takes a single argument which
+** is a pointer to an instance of the [sqlite3_mutex_methods] structure.  The
+** [sqlite3_mutex_methods]
+** structure is filled with the currently defined mutex routines.)^
+** This option can be used to overload the default mutex allocation
+** routines with a wrapper used to track mutex usage for performance
+** profiling or testing, for example.   ^If SQLite is compiled with
+** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
+** the entire mutexing subsystem is omitted from the build and hence calls to
+** [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will
+** return [SQLITE_ERROR].</dd>
+**
+** [[SQLITE_CONFIG_LOOKASIDE]] <dt>SQLITE_CONFIG_LOOKASIDE</dt>
+** <dd> ^(The SQLITE_CONFIG_LOOKASIDE option takes two arguments that determine
+** the default size of lookaside memory on each [database connection].
+** The first argument is the
+** size of each lookaside buffer slot and the second is the number of
+** slots allocated to each database connection.)^  ^(SQLITE_CONFIG_LOOKASIDE
+** sets the <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE]
+** option to [sqlite3_db_config()] can be used to change the lookaside
+** configuration on individual connections.)^ </dd>
+**
+** [[SQLITE_CONFIG_PCACHE2]] <dt>SQLITE_CONFIG_PCACHE2</dt>
+** <dd> ^(The SQLITE_CONFIG_PCACHE2 option takes a single argument which is 
+** a pointer to an [sqlite3_pcache_methods2] object.  This object specifies
+** the interface to a custom page cache implementation.)^
+** ^SQLite makes a copy of the [sqlite3_pcache_methods2] object.</dd>
+**
+** [[SQLITE_CONFIG_GETPCACHE2]] <dt>SQLITE_CONFIG_GETPCACHE2</dt>
+** <dd> ^(The SQLITE_CONFIG_GETPCACHE2 option takes a single argument which
+** is a pointer to an [sqlite3_pcache_methods2] object.  SQLite copies of
+** the current page cache implementation into that object.)^ </dd>
+**
+** [[SQLITE_CONFIG_LOG]] <dt>SQLITE_CONFIG_LOG</dt>
+** <dd> The SQLITE_CONFIG_LOG option is used to configure the SQLite
+** global [error log].
+** (^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
+** function with a call signature of void(*)(void*,int,const char*), 
+** and a pointer to void. ^If the function pointer is not NULL, it is
+** invoked by [sqlite3_log()] to process each logging event.  ^If the
+** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.
+** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is
+** passed through as the first parameter to the application-defined logger
+** function whenever that function is invoked.  ^The second parameter to
+** the logger function is a copy of the first parameter to the corresponding
+** [sqlite3_log()] call and is intended to be a [result code] or an
+** [extended result code].  ^The third parameter passed to the logger is
+** log message after formatting via [sqlite3_snprintf()].
+** The SQLite logging interface is not reentrant; the logger function
+** supplied by the application must not invoke any SQLite interface.
+** In a multi-threaded application, the application-defined logger
+** function must be threadsafe. </dd>
+**
+** [[SQLITE_CONFIG_URI]] <dt>SQLITE_CONFIG_URI
+** <dd>^(The SQLITE_CONFIG_URI option takes a single argument of type int.
+** If non-zero, then URI handling is globally enabled. If the parameter is zero,
+** then URI handling is globally disabled.)^ ^If URI handling is globally
+** enabled, all filenames passed to [sqlite3_open()], [sqlite3_open_v2()],
+** [sqlite3_open16()] or
+** specified as part of [ATTACH] commands are interpreted as URIs, regardless
+** of whether or not the [SQLITE_OPEN_URI] flag is set when the database
+** connection is opened. ^If it is globally disabled, filenames are
+** only interpreted as URIs if the SQLITE_OPEN_URI flag is set when the
+** database connection is opened. ^(By default, URI handling is globally
+** disabled. The default value may be changed by compiling with the
+** [SQLITE_USE_URI] symbol defined.)^
+**
+** [[SQLITE_CONFIG_COVERING_INDEX_SCAN]] <dt>SQLITE_CONFIG_COVERING_INDEX_SCAN
+** <dd>^The SQLITE_CONFIG_COVERING_INDEX_SCAN option takes a single integer
+** argument which is interpreted as a boolean in order to enable or disable
+** the use of covering indices for full table scans in the query optimizer.
+** ^The default setting is determined
+** by the [SQLITE_ALLOW_COVERING_INDEX_SCAN] compile-time option, or is "on"
+** if that compile-time option is omitted.
+** The ability to disable the use of covering indices for full table scans
+** is because some incorrectly coded legacy applications might malfunction
+** when the optimization is enabled.  Providing the ability to
+** disable the optimization allows the older, buggy application code to work
+** without change even with newer versions of SQLite.
+**
+** [[SQLITE_CONFIG_PCACHE]] [[SQLITE_CONFIG_GETPCACHE]]
+** <dt>SQLITE_CONFIG_PCACHE and SQLITE_CONFIG_GETPCACHE
+** <dd> These options are obsolete and should not be used by new code.
+** They are retained for backwards compatibility but are now no-ops.
+** </dd>
+**
+** [[SQLITE_CONFIG_SQLLOG]]
+** <dt>SQLITE_CONFIG_SQLLOG
+** <dd>This option is only available if sqlite is compiled with the
+** [SQLITE_ENABLE_SQLLOG] pre-processor macro defined. The first argument should
+** be a pointer to a function of type void(*)(void*,sqlite3*,const char*, int).
+** The second should be of type (void*). The callback is invoked by the library
+** in three separate circumstances, identified by the value passed as the
+** fourth parameter. If the fourth parameter is 0, then the database connection
+** passed as the second argument has just been opened. The third argument
+** points to a buffer containing the name of the main database file. If the
+** fourth parameter is 1, then the SQL statement that the third parameter
+** points to has just been executed. Or, if the fourth parameter is 2, then
+** the connection being passed as the second parameter is being closed. The
+** third parameter is passed NULL In this case.  An example of using this
+** configuration option can be seen in the "test_sqllog.c" source file in
+** the canonical SQLite source tree.</dd>
+**
+** [[SQLITE_CONFIG_MMAP_SIZE]]
+** <dt>SQLITE_CONFIG_MMAP_SIZE
+** <dd>^SQLITE_CONFIG_MMAP_SIZE takes two 64-bit integer (sqlite3_int64) values
+** that are the default mmap size limit (the default setting for
+** [PRAGMA mmap_size]) and the maximum allowed mmap size limit.
+** ^The default setting can be overridden by each database connection using
+** either the [PRAGMA mmap_size] command, or by using the
+** [SQLITE_FCNTL_MMAP_SIZE] file control.  ^(The maximum allowed mmap size
+** will be silently truncated if necessary so that it does not exceed the
+** compile-time maximum mmap size set by the
+** [SQLITE_MAX_MMAP_SIZE] compile-time option.)^
+** ^If either argument to this option is negative, then that argument is
+** changed to its compile-time default.
+**
+** [[SQLITE_CONFIG_WIN32_HEAPSIZE]]
+** <dt>SQLITE_CONFIG_WIN32_HEAPSIZE
+** <dd>^The SQLITE_CONFIG_WIN32_HEAPSIZE option is only available if SQLite is
+** compiled for Windows with the [SQLITE_WIN32_MALLOC] pre-processor macro
+** defined. ^SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit unsigned integer value
+** that specifies the maximum size of the created heap.
+**
+** [[SQLITE_CONFIG_PCACHE_HDRSZ]]
+** <dt>SQLITE_CONFIG_PCACHE_HDRSZ
+** <dd>^The SQLITE_CONFIG_PCACHE_HDRSZ option takes a single parameter which
+** is a pointer to an integer and writes into that integer the number of extra
+** bytes per page required for each page in [SQLITE_CONFIG_PAGECACHE].
+** The amount of extra space required can change depending on the compiler,
+** target platform, and SQLite version.
+**
+** [[SQLITE_CONFIG_PMASZ]]
+** <dt>SQLITE_CONFIG_PMASZ
+** <dd>^The SQLITE_CONFIG_PMASZ option takes a single parameter which
+** is an unsigned integer and sets the "Minimum PMA Size" for the multithreaded
+** sorter to that integer.  The default minimum PMA Size is set by the
+** [SQLITE_SORTER_PMASZ] compile-time option.  New threads are launched
+** to help with sort operations when multithreaded sorting
+** is enabled (using the [PRAGMA threads] command) and the amount of content
+** to be sorted exceeds the page size times the minimum of the
+** [PRAGMA cache_size] setting and this value.
+**
+** [[SQLITE_CONFIG_STMTJRNL_SPILL]]
+** <dt>SQLITE_CONFIG_STMTJRNL_SPILL
+** <dd>^The SQLITE_CONFIG_STMTJRNL_SPILL option takes a single parameter which
+** becomes the [statement journal] spill-to-disk threshold.  
+** [Statement journals] are held in memory until their size (in bytes)
+** exceeds this threshold, at which point they are written to disk.
+** Or if the threshold is -1, statement journals are always held
+** exclusively in memory.
+** Since many statement journals never become large, setting the spill
+** threshold to a value such as 64KiB can greatly reduce the amount of
+** I/O required to support statement rollback.
+** The default value for this setting is controlled by the
+** [SQLITE_STMTJRNL_SPILL] compile-time option.
+** </dl>
+*/
+#define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
+#define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
+#define SQLITE_CONFIG_SERIALIZED    3  /* nil */
+#define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
+#define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
+#define SQLITE_CONFIG_SCRATCH       6  /* void*, int sz, int N */
+#define SQLITE_CONFIG_PAGECACHE     7  /* void*, int sz, int N */
+#define SQLITE_CONFIG_HEAP          8  /* void*, int nByte, int min */
+#define SQLITE_CONFIG_MEMSTATUS     9  /* boolean */
+#define SQLITE_CONFIG_MUTEX        10  /* sqlite3_mutex_methods* */
+#define SQLITE_CONFIG_GETMUTEX     11  /* sqlite3_mutex_methods* */
+/* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */ 
+#define SQLITE_CONFIG_LOOKASIDE    13  /* int int */
+#define SQLITE_CONFIG_PCACHE       14  /* no-op */
+#define SQLITE_CONFIG_GETPCACHE    15  /* no-op */
+#define SQLITE_CONFIG_LOG          16  /* xFunc, void* */
+#define SQLITE_CONFIG_URI          17  /* int */
+#define SQLITE_CONFIG_PCACHE2      18  /* sqlite3_pcache_methods2* */
+#define SQLITE_CONFIG_GETPCACHE2   19  /* sqlite3_pcache_methods2* */
+#define SQLITE_CONFIG_COVERING_INDEX_SCAN 20  /* int */
+#define SQLITE_CONFIG_SQLLOG       21  /* xSqllog, void* */
+#define SQLITE_CONFIG_MMAP_SIZE    22  /* sqlite3_int64, sqlite3_int64 */
+#define SQLITE_CONFIG_WIN32_HEAPSIZE      23  /* int nByte */
+#define SQLITE_CONFIG_PCACHE_HDRSZ        24  /* int *psz */
+#define SQLITE_CONFIG_PMASZ               25  /* unsigned int szPma */
+#define SQLITE_CONFIG_STMTJRNL_SPILL      26  /* int nByte */
+
+/*
+** CAPI3REF: Database Connection Configuration Options
+**
+** These constants are the available integer configuration options that
+** can be passed as the second argument to the [sqlite3_db_config()] interface.
+**
+** New configuration options may be added in future releases of SQLite.
+** Existing configuration options might be discontinued.  Applications
+** should check the return code from [sqlite3_db_config()] to make sure that
+** the call worked.  ^The [sqlite3_db_config()] interface will return a
+** non-zero [error code] if a discontinued or unsupported configuration option
+** is invoked.
+**
+** <dl>
+** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
+** <dd> ^This option takes three additional arguments that determine the 
+** [lookaside memory allocator] configuration for the [database connection].
+** ^The first argument (the third parameter to [sqlite3_db_config()] is a
+** pointer to a memory buffer to use for lookaside memory.
+** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
+** may be NULL in which case SQLite will allocate the
+** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the
+** size of each lookaside buffer slot.  ^The third argument is the number of
+** slots.  The size of the buffer in the first argument must be greater than
+** or equal to the product of the second and third arguments.  The buffer
+** must be aligned to an 8-byte boundary.  ^If the second argument to
+** SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally
+** rounded down to the next smaller multiple of 8.  ^(The lookaside memory
+** configuration for a database connection can only be changed when that
+** connection is not currently using lookaside memory, or in other words
+** when the "current value" returned by
+** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.
+** Any attempt to change the lookaside memory configuration when lookaside
+** memory is in use leaves the configuration unchanged and returns 
+** [SQLITE_BUSY].)^</dd>
+**
+** <dt>SQLITE_DBCONFIG_ENABLE_FKEY</dt>
+** <dd> ^This option is used to enable or disable the enforcement of
+** [foreign key constraints].  There should be two additional arguments.
+** The first argument is an integer which is 0 to disable FK enforcement,
+** positive to enable FK enforcement or negative to leave FK enforcement
+** unchanged.  The second parameter is a pointer to an integer into which
+** is written 0 or 1 to indicate whether FK enforcement is off or on
+** following this call.  The second parameter may be a NULL pointer, in
+** which case the FK enforcement setting is not reported back. </dd>
+**
+** <dt>SQLITE_DBCONFIG_ENABLE_TRIGGER</dt>
+** <dd> ^This option is used to enable or disable [CREATE TRIGGER | triggers].
+** There should be two additional arguments.
+** The first argument is an integer which is 0 to disable triggers,
+** positive to enable triggers or negative to leave the setting unchanged.
+** The second parameter is a pointer to an integer into which
+** is written 0 or 1 to indicate whether triggers are disabled or enabled
+** following this call.  The second parameter may be a NULL pointer, in
+** which case the trigger setting is not reported back. </dd>
+**
+** <dt>SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER</dt>
+** <dd> ^This option is used to enable or disable the two-argument
+** version of the [fts3_tokenizer()] function which is part of the
+** [FTS3] full-text search engine extension.
+** There should be two additional arguments.
+** The first argument is an integer which is 0 to disable fts3_tokenizer() or
+** positive to enable fts3_tokenizer() or negative to leave the setting
+** unchanged.
+** The second parameter is a pointer to an integer into which
+** is written 0 or 1 to indicate whether fts3_tokenizer is disabled or enabled
+** following this call.  The second parameter may be a NULL pointer, in
+** which case the new setting is not reported back. </dd>
+**
+** <dt>SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION</dt>
+** <dd> ^This option is used to enable or disable the [sqlite3_load_extension()]
+** interface independently of the [load_extension()] SQL function.
+** The [sqlite3_enable_load_extension()] API enables or disables both the
+** C-API [sqlite3_load_extension()] and the SQL function [load_extension()].
+** There should be two additional arguments.
+** When the first argument to this interface is 1, then only the C-API is
+** enabled and the SQL function remains disabled.  If the first argument to
+** this interface is 0, then both the C-API and the SQL function are disabled.
+** If the first argument is -1, then no changes are made to state of either the
+** C-API or the SQL function.
+** The second parameter is a pointer to an integer into which
+** is written 0 or 1 to indicate whether [sqlite3_load_extension()] interface
+** is disabled or enabled following this call.  The second parameter may
+** be a NULL pointer, in which case the new setting is not reported back.
+** </dd>
+**
+** <dt>SQLITE_DBCONFIG_MAINDBNAME</dt>
+** <dd> ^This option is used to change the name of the "main" database
+** schema.  ^The sole argument is a pointer to a constant UTF8 string
+** which will become the new schema name in place of "main".  ^SQLite
+** does not make a copy of the new main schema name string, so the application
+** must ensure that the argument passed into this DBCONFIG option is unchanged
+** until after the database connection closes.
+** </dd>
+**
+** </dl>
+*/
+#define SQLITE_DBCONFIG_MAINDBNAME            1000 /* const char* */
+#define SQLITE_DBCONFIG_LOOKASIDE             1001 /* void* int int */
+#define SQLITE_DBCONFIG_ENABLE_FKEY           1002 /* int int* */
+#define SQLITE_DBCONFIG_ENABLE_TRIGGER        1003 /* int int* */
+#define SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER 1004 /* int int* */
+#define SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION 1005 /* int int* */
+
+
+/*
+** CAPI3REF: Enable Or Disable Extended Result Codes
+** METHOD: sqlite3
+**
+** ^The sqlite3_extended_result_codes() routine enables or disables the
+** [extended result codes] feature of SQLite. ^The extended result
+** codes are disabled by default for historical compatibility.
+*/
+SQLITE_API int sqlite3_extended_result_codes(sqlite3*, int onoff);
+
+/*
+** CAPI3REF: Last Insert Rowid
+** METHOD: sqlite3
+**
+** ^Each entry in most SQLite tables (except for [WITHOUT ROWID] tables)
+** has a unique 64-bit signed
+** integer key called the [ROWID | "rowid"]. ^The rowid is always available
+** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
+** names are not also used by explicitly declared columns. ^If
+** the table has a column of type [INTEGER PRIMARY KEY] then that column
+** is another alias for the rowid.
+**
+** ^The sqlite3_last_insert_rowid(D) interface returns the [rowid] of the 
+** most recent successful [INSERT] into a rowid table or [virtual table]
+** on database connection D.
+** ^Inserts into [WITHOUT ROWID] tables are not recorded.
+** ^If no successful [INSERT]s into rowid tables
+** have ever occurred on the database connection D, 
+** then sqlite3_last_insert_rowid(D) returns zero.
+**
+** ^(If an [INSERT] occurs within a trigger or within a [virtual table]
+** method, then this routine will return the [rowid] of the inserted
+** row as long as the trigger or virtual table method is running.
+** But once the trigger or virtual table method ends, the value returned 
+** by this routine reverts to what it was before the trigger or virtual
+** table method began.)^
+**
+** ^An [INSERT] that fails due to a constraint violation is not a
+** successful [INSERT] and does not change the value returned by this
+** routine.  ^Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,
+** and INSERT OR ABORT make no changes to the return value of this
+** routine when their insertion fails.  ^(When INSERT OR REPLACE
+** encounters a constraint violation, it does not fail.  The
+** INSERT continues to completion after deleting rows that caused
+** the constraint problem so INSERT OR REPLACE will always change
+** the return value of this interface.)^
+**
+** ^For the purposes of this routine, an [INSERT] is considered to
+** be successful even if it is subsequently rolled back.
+**
+** This function is accessible to SQL statements via the
+** [last_insert_rowid() SQL function].
+**
+** If a separate thread performs a new [INSERT] on the same
+** database connection while the [sqlite3_last_insert_rowid()]
+** function is running and thus changes the last insert [rowid],
+** then the value returned by [sqlite3_last_insert_rowid()] is
+** unpredictable and might not equal either the old or the new
+** last insert [rowid].
+*/
+SQLITE_API sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*);
+
+/*
+** CAPI3REF: Count The Number Of Rows Modified
+** METHOD: sqlite3
+**
+** ^This function returns the number of rows modified, inserted or
+** deleted by the most recently completed INSERT, UPDATE or DELETE
+** statement on the database connection specified by the only parameter.
+** ^Executing any other type of SQL statement does not modify the value
+** returned by this function.
+**
+** ^Only changes made directly by the INSERT, UPDATE or DELETE statement are
+** considered - auxiliary changes caused by [CREATE TRIGGER | triggers], 
+** [foreign key actions] or [REPLACE] constraint resolution are not counted.
+** 
+** Changes to a view that are intercepted by 
+** [INSTEAD OF trigger | INSTEAD OF triggers] are not counted. ^The value 
+** returned by sqlite3_changes() immediately after an INSERT, UPDATE or 
+** DELETE statement run on a view is always zero. Only changes made to real 
+** tables are counted.
+**
+** Things are more complicated if the sqlite3_changes() function is
+** executed while a trigger program is running. This may happen if the
+** program uses the [changes() SQL function], or if some other callback
+** function invokes sqlite3_changes() directly. Essentially:
+** 
+** <ul>
+**   <li> ^(Before entering a trigger program the value returned by
+**        sqlite3_changes() function is saved. After the trigger program 
+**        has finished, the original value is restored.)^
+** 
+**   <li> ^(Within a trigger program each INSERT, UPDATE and DELETE 
+**        statement sets the value returned by sqlite3_changes() 
+**        upon completion as normal. Of course, this value will not include 
+**        any changes performed by sub-triggers, as the sqlite3_changes() 
+**        value will be saved and restored after each sub-trigger has run.)^
+** </ul>
+** 
+** ^This means that if the changes() SQL function (or similar) is used
+** by the first INSERT, UPDATE or DELETE statement within a trigger, it 
+** returns the value as set when the calling statement began executing.
+** ^If it is used by the second or subsequent such statement within a trigger 
+** program, the value returned reflects the number of rows modified by the 
+** previous INSERT, UPDATE or DELETE statement within the same trigger.
+**
+** See also the [sqlite3_total_changes()] interface, the
+** [count_changes pragma], and the [changes() SQL function].
+**
+** If a separate thread makes changes on the same database connection
+** while [sqlite3_changes()] is running then the value returned
+** is unpredictable and not meaningful.
+*/
+SQLITE_API int sqlite3_changes(sqlite3*);
+
+/*
+** CAPI3REF: Total Number Of Rows Modified
+** METHOD: sqlite3
+**
+** ^This function returns the total number of rows inserted, modified or
+** deleted by all [INSERT], [UPDATE] or [DELETE] statements completed
+** since the database connection was opened, including those executed as
+** part of trigger programs. ^Executing any other type of SQL statement
+** does not affect the value returned by sqlite3_total_changes().
+** 
+** ^Changes made as part of [foreign key actions] are included in the
+** count, but those made as part of REPLACE constraint resolution are
+** not. ^Changes to a view that are intercepted by INSTEAD OF triggers 
+** are not counted.
+** 
+** See also the [sqlite3_changes()] interface, the
+** [count_changes pragma], and the [total_changes() SQL function].
+**
+** If a separate thread makes changes on the same database connection
+** while [sqlite3_total_changes()] is running then the value
+** returned is unpredictable and not meaningful.
+*/
+SQLITE_API int sqlite3_total_changes(sqlite3*);
+
+/*
+** CAPI3REF: Interrupt A Long-Running Query
+** METHOD: sqlite3
+**
+** ^This function causes any pending database operation to abort and
+** return at its earliest opportunity. This routine is typically
+** called in response to a user action such as pressing "Cancel"
+** or Ctrl-C where the user wants a long query operation to halt
+** immediately.
+**
+** ^It is safe to call this routine from a thread different from the
+** thread that is currently running the database operation.  But it
+** is not safe to call this routine with a [database connection] that
+** is closed or might close before sqlite3_interrupt() returns.
+**
+** ^If an SQL operation is very nearly finished at the time when
+** sqlite3_interrupt() is called, then it might not have an opportunity
+** to be interrupted and might continue to completion.
+**
+** ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT].
+** ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE
+** that is inside an explicit transaction, then the entire transaction
+** will be rolled back automatically.
+**
+** ^The sqlite3_interrupt(D) call is in effect until all currently running
+** SQL statements on [database connection] D complete.  ^Any new SQL statements
+** that are started after the sqlite3_interrupt() call and before the 
+** running statements reaches zero are interrupted as if they had been
+** running prior to the sqlite3_interrupt() call.  ^New SQL statements
+** that are started after the running statement count reaches zero are
+** not effected by the sqlite3_interrupt().
+** ^A call to sqlite3_interrupt(D) that occurs when there are no running
+** SQL statements is a no-op and has no effect on SQL statements
+** that are started after the sqlite3_interrupt() call returns.
+**
+** If the database connection closes while [sqlite3_interrupt()]
+** is running then bad things will likely happen.
+*/
+SQLITE_API void sqlite3_interrupt(sqlite3*);
+
+/*
+** CAPI3REF: Determine If An SQL Statement Is Complete
+**
+** These routines are useful during command-line input to determine if the
+** currently entered text seems to form a complete SQL statement or
+** if additional input is needed before sending the text into
+** SQLite for parsing.  ^These routines return 1 if the input string
+** appears to be a complete SQL statement.  ^A statement is judged to be
+** complete if it ends with a semicolon token and is not a prefix of a
+** well-formed CREATE TRIGGER statement.  ^Semicolons that are embedded within
+** string literals or quoted identifier names or comments are not
+** independent tokens (they are part of the token in which they are
+** embedded) and thus do not count as a statement terminator.  ^Whitespace
+** and comments that follow the final semicolon are ignored.
+**
+** ^These routines return 0 if the statement is incomplete.  ^If a
+** memory allocation fails, then SQLITE_NOMEM is returned.
+**
+** ^These routines do not parse the SQL statements thus
+** will not detect syntactically incorrect SQL.
+**
+** ^(If SQLite has not been initialized using [sqlite3_initialize()] prior 
+** to invoking sqlite3_complete16() then sqlite3_initialize() is invoked
+** automatically by sqlite3_complete16().  If that initialization fails,
+** then the return value from sqlite3_complete16() will be non-zero
+** regardless of whether or not the input SQL is complete.)^
+**
+** The input to [sqlite3_complete()] must be a zero-terminated
+** UTF-8 string.
+**
+** The input to [sqlite3_complete16()] must be a zero-terminated
+** UTF-16 string in native byte order.
+*/
+SQLITE_API int sqlite3_complete(const char *sql);
+SQLITE_API int sqlite3_complete16(const void *sql);
+
+/*
+** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors
+** KEYWORDS: {busy-handler callback} {busy handler}
+** METHOD: sqlite3
+**
+** ^The sqlite3_busy_handler(D,X,P) routine sets a callback function X
+** that might be invoked with argument P whenever
+** an attempt is made to access a database table associated with
+** [database connection] D when another thread
+** or process has the table locked.
+** The sqlite3_busy_handler() interface is used to implement
+** [sqlite3_busy_timeout()] and [PRAGMA busy_timeout].
+**
+** ^If the busy callback is NULL, then [SQLITE_BUSY]
+** is returned immediately upon encountering the lock.  ^If the busy callback
+** is not NULL, then the callback might be invoked with two arguments.
+**
+** ^The first argument to the busy handler is a copy of the void* pointer which
+** is the third argument to sqlite3_busy_handler().  ^The second argument to
+** the busy handler callback is the number of times that the busy handler has
+** been invoked previously for the same locking event.  ^If the
+** busy callback returns 0, then no additional attempts are made to
+** access the database and [SQLITE_BUSY] is returned
+** to the application.
+** ^If the callback returns non-zero, then another attempt
+** is made to access the database and the cycle repeats.
+**
+** The presence of a busy handler does not guarantee that it will be invoked
+** when there is lock contention. ^If SQLite determines that invoking the busy
+** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]
+** to the application instead of invoking the 
+** busy handler.
+** Consider a scenario where one process is holding a read lock that
+** it is trying to promote to a reserved lock and
+** a second process is holding a reserved lock that it is trying
+** to promote to an exclusive lock.  The first process cannot proceed
+** because it is blocked by the second and the second process cannot
+** proceed because it is blocked by the first.  If both processes
+** invoke the busy handlers, neither will make any progress.  Therefore,
+** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
+** will induce the first process to release its read lock and allow
+** the second process to proceed.
+**
+** ^The default busy callback is NULL.
+**
+** ^(There can only be a single busy handler defined for each
+** [database connection].  Setting a new busy handler clears any
+** previously set handler.)^  ^Note that calling [sqlite3_busy_timeout()]
+** or evaluating [PRAGMA busy_timeout=N] will change the
+** busy handler and thus clear any previously set busy handler.
+**
+** The busy callback should not take any actions which modify the
+** database connection that invoked the busy handler.  In other words,
+** the busy handler is not reentrant.  Any such actions
+** result in undefined behavior.
+** 
+** A busy handler must not close the database connection
+** or [prepared statement] that invoked the busy handler.
+*/
+SQLITE_API int sqlite3_busy_handler(sqlite3*,int(*)(void*,int),void*);
+
+/*
+** CAPI3REF: Set A Busy Timeout
+** METHOD: sqlite3
+**
+** ^This routine sets a [sqlite3_busy_handler | busy handler] that sleeps
+** for a specified amount of time when a table is locked.  ^The handler
+** will sleep multiple times until at least "ms" milliseconds of sleeping
+** have accumulated.  ^After at least "ms" milliseconds of sleeping,
+** the handler returns 0 which causes [sqlite3_step()] to return
+** [SQLITE_BUSY].
+**
+** ^Calling this routine with an argument less than or equal to zero
+** turns off all busy handlers.
+**
+** ^(There can only be a single busy handler for a particular
+** [database connection] at any given moment.  If another busy handler
+** was defined  (using [sqlite3_busy_handler()]) prior to calling
+** this routine, that other busy handler is cleared.)^
+**
+** See also:  [PRAGMA busy_timeout]
+*/
+SQLITE_API int sqlite3_busy_timeout(sqlite3*, int ms);
+
+/*
+** CAPI3REF: Convenience Routines For Running Queries
+** METHOD: sqlite3
+**
+** This is a legacy interface that is preserved for backwards compatibility.
+** Use of this interface is not recommended.
+**
+** Definition: A <b>result table</b> is memory data structure created by the
+** [sqlite3_get_table()] interface.  A result table records the
+** complete query results from one or more queries.
+**
+** The table conceptually has a number of rows and columns.  But
+** these numbers are not part of the result table itself.  These
+** numbers are obtained separately.  Let N be the number of rows
+** and M be the number of columns.
+**
+** A result table is an array of pointers to zero-terminated UTF-8 strings.
+** There are (N+1)*M elements in the array.  The first M pointers point
+** to zero-terminated strings that  contain the names of the columns.
+** The remaining entries all point to query results.  NULL values result
+** in NULL pointers.  All other values are in their UTF-8 zero-terminated
+** string representation as returned by [sqlite3_column_text()].
+**
+** A result table might consist of one or more memory allocations.
+** It is not safe to pass a result table directly to [sqlite3_free()].
+** A result table should be deallocated using [sqlite3_free_table()].
+**
+** ^(As an example of the result table format, suppose a query result
+** is as follows:
+**
+** <blockquote><pre>
+**        Name        | Age
+**        -----------------------
+**        Alice       | 43
+**        Bob         | 28
+**        Cindy       | 21
+** </pre></blockquote>
+**
+** There are two column (M==2) and three rows (N==3).  Thus the
+** result table has 8 entries.  Suppose the result table is stored
+** in an array names azResult.  Then azResult holds this content:
+**
+** <blockquote><pre>
+**        azResult&#91;0] = "Name";
+**        azResult&#91;1] = "Age";
+**        azResult&#91;2] = "Alice";
+**        azResult&#91;3] = "43";
+**        azResult&#91;4] = "Bob";
+**        azResult&#91;5] = "28";
+**        azResult&#91;6] = "Cindy";
+**        azResult&#91;7] = "21";
+** </pre></blockquote>)^
+**
+** ^The sqlite3_get_table() function evaluates one or more
+** semicolon-separated SQL statements in the zero-terminated UTF-8
+** string of its 2nd parameter and returns a result table to the
+** pointer given in its 3rd parameter.
+**
+** After the application has finished with the result from sqlite3_get_table(),
+** it must pass the result table pointer to sqlite3_free_table() in order to
+** release the memory that was malloced.  Because of the way the
+** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling
+** function must not try to call [sqlite3_free()] directly.  Only
+** [sqlite3_free_table()] is able to release the memory properly and safely.
+**
+** The sqlite3_get_table() interface is implemented as a wrapper around
+** [sqlite3_exec()].  The sqlite3_get_table() routine does not have access
+** to any internal data structures of SQLite.  It uses only the public
+** interface defined here.  As a consequence, errors that occur in the
+** wrapper layer outside of the internal [sqlite3_exec()] call are not
+** reflected in subsequent calls to [sqlite3_errcode()] or
+** [sqlite3_errmsg()].
+*/
+SQLITE_API int sqlite3_get_table(
+  sqlite3 *db,          /* An open database */
+  const char *zSql,     /* SQL to be evaluated */
+  char ***pazResult,    /* Results of the query */
+  int *pnRow,           /* Number of result rows written here */
+  int *pnColumn,        /* Number of result columns written here */
+  char **pzErrmsg       /* Error msg written here */
+);
+SQLITE_API void sqlite3_free_table(char **result);
+
+/*
+** CAPI3REF: Formatted String Printing Functions
+**
+** These routines are work-alikes of the "printf()" family of functions
+** from the standard C library.
+** These routines understand most of the common K&R formatting options,
+** plus some additional non-standard formats, detailed below.
+** Note that some of the more obscure formatting options from recent
+** C-library standards are omitted from this implementation.
+**
+** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
+** results into memory obtained from [sqlite3_malloc()].
+** The strings returned by these two routines should be
+** released by [sqlite3_free()].  ^Both routines return a
+** NULL pointer if [sqlite3_malloc()] is unable to allocate enough
+** memory to hold the resulting string.
+**
+** ^(The sqlite3_snprintf() routine is similar to "snprintf()" from
+** the standard C library.  The result is written into the
+** buffer supplied as the second parameter whose size is given by
+** the first parameter. Note that the order of the
+** first two parameters is reversed from snprintf().)^  This is an
+** historical accident that cannot be fixed without breaking
+** backwards compatibility.  ^(Note also that sqlite3_snprintf()
+** returns a pointer to its buffer instead of the number of
+** characters actually written into the buffer.)^  We admit that
+** the number of characters written would be a more useful return
+** value but we cannot change the implementation of sqlite3_snprintf()
+** now without breaking compatibility.
+**
+** ^As long as the buffer size is greater than zero, sqlite3_snprintf()
+** guarantees that the buffer is always zero-terminated.  ^The first
+** parameter "n" is the total size of the buffer, including space for
+** the zero terminator.  So the longest string that can be completely
+** written will be n-1 characters.
+**
+** ^The sqlite3_vsnprintf() routine is a varargs version of sqlite3_snprintf().
+**
+** These routines all implement some additional formatting
+** options that are useful for constructing SQL statements.
+** All of the usual printf() formatting options apply.  In addition, there
+** is are "%q", "%Q", "%w" and "%z" options.
+**
+** ^(The %q option works like %s in that it substitutes a nul-terminated
+** string from the argument list.  But %q also doubles every '\'' character.
+** %q is designed for use inside a string literal.)^  By doubling each '\''
+** character it escapes that character and allows it to be inserted into
+** the string.
+**
+** For example, assume the string variable zText contains text as follows:
+**
+** <blockquote><pre>
+**  char *zText = "It's a happy day!";
+** </pre></blockquote>
+**
+** One can use this text in an SQL statement as follows:
+**
+** <blockquote><pre>
+**  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText);
+**  sqlite3_exec(db, zSQL, 0, 0, 0);
+**  sqlite3_free(zSQL);
+** </pre></blockquote>
+**
+** Because the %q format string is used, the '\'' character in zText
+** is escaped and the SQL generated is as follows:
+**
+** <blockquote><pre>
+**  INSERT INTO table1 VALUES('It''s a happy day!')
+** </pre></blockquote>
+**
+** This is correct.  Had we used %s instead of %q, the generated SQL
+** would have looked like this:
+**
+** <blockquote><pre>
+**  INSERT INTO table1 VALUES('It's a happy day!');
+** </pre></blockquote>
+**
+** This second example is an SQL syntax error.  As a general rule you should
+** always use %q instead of %s when inserting text into a string literal.
+**
+** ^(The %Q option works like %q except it also adds single quotes around
+** the outside of the total string.  Additionally, if the parameter in the
+** argument list is a NULL pointer, %Q substitutes the text "NULL" (without
+** single quotes).)^  So, for example, one could say:
+**
+** <blockquote><pre>
+**  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText);
+**  sqlite3_exec(db, zSQL, 0, 0, 0);
+**  sqlite3_free(zSQL);
+** </pre></blockquote>
+**
+** The code above will render a correct SQL statement in the zSQL
+** variable even if the zText variable is a NULL pointer.
+**
+** ^(The "%w" formatting option is like "%q" except that it expects to
+** be contained within double-quotes instead of single quotes, and it
+** escapes the double-quote character instead of the single-quote
+** character.)^  The "%w" formatting option is intended for safely inserting
+** table and column names into a constructed SQL statement.
+**
+** ^(The "%z" formatting option works like "%s" but with the
+** addition that after the string has been read and copied into
+** the result, [sqlite3_free()] is called on the input string.)^
+*/
+SQLITE_API char *sqlite3_mprintf(const char*,...);
+SQLITE_API char *sqlite3_vmprintf(const char*, va_list);
+SQLITE_API char *sqlite3_snprintf(int,char*,const char*, ...);
+SQLITE_API char *sqlite3_vsnprintf(int,char*,const char*, va_list);
+
+/*
+** CAPI3REF: Memory Allocation Subsystem
+**
+** The SQLite core uses these three routines for all of its own
+** internal memory allocation needs. "Core" in the previous sentence
+** does not include operating-system specific VFS implementation.  The
+** Windows VFS uses native malloc() and free() for some operations.
+**
+** ^The sqlite3_malloc() routine returns a pointer to a block
+** of memory at least N bytes in length, where N is the parameter.
+** ^If sqlite3_malloc() is unable to obtain sufficient free
+** memory, it returns a NULL pointer.  ^If the parameter N to
+** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns
+** a NULL pointer.
+**
+** ^The sqlite3_malloc64(N) routine works just like
+** sqlite3_malloc(N) except that N is an unsigned 64-bit integer instead
+** of a signed 32-bit integer.
+**
+** ^Calling sqlite3_free() with a pointer previously returned
+** by sqlite3_malloc() or sqlite3_realloc() releases that memory so
+** that it might be reused.  ^The sqlite3_free() routine is
+** a no-op if is called with a NULL pointer.  Passing a NULL pointer
+** to sqlite3_free() is harmless.  After being freed, memory
+** should neither be read nor written.  Even reading previously freed
+** memory might result in a segmentation fault or other severe error.
+** Memory corruption, a segmentation fault, or other severe error
+** might result if sqlite3_free() is called with a non-NULL pointer that
+** was not obtained from sqlite3_malloc() or sqlite3_realloc().
+**
+** ^The sqlite3_realloc(X,N) interface attempts to resize a
+** prior memory allocation X to be at least N bytes.
+** ^If the X parameter to sqlite3_realloc(X,N)
+** is a NULL pointer then its behavior is identical to calling
+** sqlite3_malloc(N).
+** ^If the N parameter to sqlite3_realloc(X,N) is zero or
+** negative then the behavior is exactly the same as calling
+** sqlite3_free(X).
+** ^sqlite3_realloc(X,N) returns a pointer to a memory allocation
+** of at least N bytes in size or NULL if insufficient memory is available.
+** ^If M is the size of the prior allocation, then min(N,M) bytes
+** of the prior allocation are copied into the beginning of buffer returned
+** by sqlite3_realloc(X,N) and the prior allocation is freed.
+** ^If sqlite3_realloc(X,N) returns NULL and N is positive, then the
+** prior allocation is not freed.
+**
+** ^The sqlite3_realloc64(X,N) interfaces works the same as
+** sqlite3_realloc(X,N) except that N is a 64-bit unsigned integer instead
+** of a 32-bit signed integer.
+**
+** ^If X is a memory allocation previously obtained from sqlite3_malloc(),
+** sqlite3_malloc64(), sqlite3_realloc(), or sqlite3_realloc64(), then
+** sqlite3_msize(X) returns the size of that memory allocation in bytes.
+** ^The value returned by sqlite3_msize(X) might be larger than the number
+** of bytes requested when X was allocated.  ^If X is a NULL pointer then
+** sqlite3_msize(X) returns zero.  If X points to something that is not
+** the beginning of memory allocation, or if it points to a formerly
+** valid memory allocation that has now been freed, then the behavior
+** of sqlite3_msize(X) is undefined and possibly harmful.
+**
+** ^The memory returned by sqlite3_malloc(), sqlite3_realloc(),
+** sqlite3_malloc64(), and sqlite3_realloc64()
+** is always aligned to at least an 8 byte boundary, or to a
+** 4 byte boundary if the [SQLITE_4_BYTE_ALIGNED_MALLOC] compile-time
+** option is used.
+**
+** In SQLite version 3.5.0 and 3.5.1, it was possible to define
+** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in
+** implementation of these routines to be omitted.  That capability
+** is no longer provided.  Only built-in memory allocators can be used.
+**
+** Prior to SQLite version 3.7.10, the Windows OS interface layer called
+** the system malloc() and free() directly when converting
+** filenames between the UTF-8 encoding used by SQLite
+** and whatever filename encoding is used by the particular Windows
+** installation.  Memory allocation errors were detected, but
+** they were reported back as [SQLITE_CANTOPEN] or
+** [SQLITE_IOERR] rather than [SQLITE_NOMEM].
+**
+** The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]
+** must be either NULL or else pointers obtained from a prior
+** invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have
+** not yet been released.
+**
+** The application must not read or write any part of
+** a block of memory after it has been released using
+** [sqlite3_free()] or [sqlite3_realloc()].
+*/
+SQLITE_API void *sqlite3_malloc(int);
+SQLITE_API void *sqlite3_malloc64(sqlite3_uint64);
+SQLITE_API void *sqlite3_realloc(void*, int);
+SQLITE_API void *sqlite3_realloc64(void*, sqlite3_uint64);
+SQLITE_API void sqlite3_free(void*);
+SQLITE_API sqlite3_uint64 sqlite3_msize(void*);
+
+/*
+** CAPI3REF: Memory Allocator Statistics
+**
+** SQLite provides these two interfaces for reporting on the status
+** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]
+** routines, which form the built-in memory allocation subsystem.
+**
+** ^The [sqlite3_memory_used()] routine returns the number of bytes
+** of memory currently outstanding (malloced but not freed).
+** ^The [sqlite3_memory_highwater()] routine returns the maximum
+** value of [sqlite3_memory_used()] since the high-water mark
+** was last reset.  ^The values returned by [sqlite3_memory_used()] and
+** [sqlite3_memory_highwater()] include any overhead
+** added by SQLite in its implementation of [sqlite3_malloc()],
+** but not overhead added by the any underlying system library
+** routines that [sqlite3_malloc()] may call.
+**
+** ^The memory high-water mark is reset to the current value of
+** [sqlite3_memory_used()] if and only if the parameter to
+** [sqlite3_memory_highwater()] is true.  ^The value returned
+** by [sqlite3_memory_highwater(1)] is the high-water mark
+** prior to the reset.
+*/
+SQLITE_API sqlite3_int64 sqlite3_memory_used(void);
+SQLITE_API sqlite3_int64 sqlite3_memory_highwater(int resetFlag);
+
+/*
+** CAPI3REF: Pseudo-Random Number Generator
+**
+** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
+** select random [ROWID | ROWIDs] when inserting new records into a table that
+** already uses the largest possible [ROWID].  The PRNG is also used for
+** the build-in random() and randomblob() SQL functions.  This interface allows
+** applications to access the same PRNG for other purposes.
+**
+** ^A call to this routine stores N bytes of randomness into buffer P.
+** ^The P parameter can be a NULL pointer.
+**
+** ^If this routine has not been previously called or if the previous
+** call had N less than one or a NULL pointer for P, then the PRNG is
+** seeded using randomness obtained from the xRandomness method of
+** the default [sqlite3_vfs] object.
+** ^If the previous call to this routine had an N of 1 or more and a
+** non-NULL P then the pseudo-randomness is generated
+** internally and without recourse to the [sqlite3_vfs] xRandomness
+** method.
+*/
+SQLITE_API void sqlite3_randomness(int N, void *P);
+
+/*
+** CAPI3REF: Compile-Time Authorization Callbacks
+** METHOD: sqlite3
+**
+** ^This routine registers an authorizer callback with a particular
+** [database connection], supplied in the first argument.
+** ^The authorizer callback is invoked as SQL statements are being compiled
+** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
+** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()].  ^At various
+** points during the compilation process, as logic is being created
+** to perform various actions, the authorizer callback is invoked to
+** see if those actions are allowed.  ^The authorizer callback should
+** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the
+** specific action but allow the SQL statement to continue to be
+** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be
+** rejected with an error.  ^If the authorizer callback returns
+** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]
+** then the [sqlite3_prepare_v2()] or equivalent call that triggered
+** the authorizer will fail with an error message.
+**
+** When the callback returns [SQLITE_OK], that means the operation
+** requested is ok.  ^When the callback returns [SQLITE_DENY], the
+** [sqlite3_prepare_v2()] or equivalent call that triggered the
+** authorizer will fail with an error message explaining that
+** access is denied. 
+**
+** ^The first parameter to the authorizer callback is a copy of the third
+** parameter to the sqlite3_set_authorizer() interface. ^The second parameter
+** to the callback is an integer [SQLITE_COPY | action code] that specifies
+** the particular action to be authorized. ^The third through sixth parameters
+** to the callback are zero-terminated strings that contain additional
+** details about the action to be authorized.
+**
+** ^If the action code is [SQLITE_READ]
+** and the callback returns [SQLITE_IGNORE] then the
+** [prepared statement] statement is constructed to substitute
+** a NULL value in place of the table column that would have
+** been read if [SQLITE_OK] had been returned.  The [SQLITE_IGNORE]
+** return can be used to deny an untrusted user access to individual
+** columns of a table.
+** ^If the action code is [SQLITE_DELETE] and the callback returns
+** [SQLITE_IGNORE] then the [DELETE] operation proceeds but the
+** [truncate optimization] is disabled and all rows are deleted individually.
+**
+** An authorizer is used when [sqlite3_prepare | preparing]
+** SQL statements from an untrusted source, to ensure that the SQL statements
+** do not try to access data they are not allowed to see, or that they do not
+** try to execute malicious statements that damage the database.  For
+** example, an application may allow a user to enter arbitrary
+** SQL queries for evaluation by a database.  But the application does
+** not want the user to be able to make arbitrary changes to the
+** database.  An authorizer could then be put in place while the
+** user-entered SQL is being [sqlite3_prepare | prepared] that
+** disallows everything except [SELECT] statements.
+**
+** Applications that need to process SQL from untrusted sources
+** might also consider lowering resource limits using [sqlite3_limit()]
+** and limiting database size using the [max_page_count] [PRAGMA]
+** in addition to using an authorizer.
+**
+** ^(Only a single authorizer can be in place on a database connection
+** at a time.  Each call to sqlite3_set_authorizer overrides the
+** previous call.)^  ^Disable the authorizer by installing a NULL callback.
+** The authorizer is disabled by default.
+**
+** The authorizer callback must not do anything that will modify
+** the database connection that invoked the authorizer callback.
+** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
+** database connections for the meaning of "modify" in this paragraph.
+**
+** ^When [sqlite3_prepare_v2()] is used to prepare a statement, the
+** statement might be re-prepared during [sqlite3_step()] due to a 
+** schema change.  Hence, the application should ensure that the
+** correct authorizer callback remains in place during the [sqlite3_step()].
+**
+** ^Note that the authorizer callback is invoked only during
+** [sqlite3_prepare()] or its variants.  Authorization is not
+** performed during statement evaluation in [sqlite3_step()], unless
+** as stated in the previous paragraph, sqlite3_step() invokes
+** sqlite3_prepare_v2() to reprepare a statement after a schema change.
+*/
+SQLITE_API int sqlite3_set_authorizer(
+  sqlite3*,
+  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
+  void *pUserData
+);
+
+/*
+** CAPI3REF: Authorizer Return Codes
+**
+** The [sqlite3_set_authorizer | authorizer callback function] must
+** return either [SQLITE_OK] or one of these two constants in order
+** to signal SQLite whether or not the action is permitted.  See the
+** [sqlite3_set_authorizer | authorizer documentation] for additional
+** information.
+**
+** Note that SQLITE_IGNORE is also used as a [conflict resolution mode]
+** returned from the [sqlite3_vtab_on_conflict()] interface.
+*/
+#define SQLITE_DENY   1   /* Abort the SQL statement with an error */
+#define SQLITE_IGNORE 2   /* Don't allow access, but don't generate an error */
+
+/*
+** CAPI3REF: Authorizer Action Codes
+**
+** The [sqlite3_set_authorizer()] interface registers a callback function
+** that is invoked to authorize certain SQL statement actions.  The
+** second parameter to the callback is an integer code that specifies
+** what action is being authorized.  These are the integer action codes that
+** the authorizer callback may be passed.
+**
+** These action code values signify what kind of operation is to be
+** authorized.  The 3rd and 4th parameters to the authorization
+** callback function will be parameters or NULL depending on which of these
+** codes is used as the second parameter.  ^(The 5th parameter to the
+** authorizer callback is the name of the database ("main", "temp",
+** etc.) if applicable.)^  ^The 6th parameter to the authorizer callback
+** is the name of the inner-most trigger or view that is responsible for
+** the access attempt or NULL if this access attempt is directly from
+** top-level SQL code.
+*/
+/******************************************* 3rd ************ 4th ***********/
+#define SQLITE_CREATE_INDEX          1   /* Index Name      Table Name      */
+#define SQLITE_CREATE_TABLE          2   /* Table Name      NULL            */
+#define SQLITE_CREATE_TEMP_INDEX     3   /* Index Name      Table Name      */
+#define SQLITE_CREATE_TEMP_TABLE     4   /* Table Name      NULL            */
+#define SQLITE_CREATE_TEMP_TRIGGER   5   /* Trigger Name    Table Name      */
+#define SQLITE_CREATE_TEMP_VIEW      6   /* View Name       NULL            */
+#define SQLITE_CREATE_TRIGGER        7   /* Trigger Name    Table Name      */
+#define SQLITE_CREATE_VIEW           8   /* View Name       NULL            */
+#define SQLITE_DELETE                9   /* Table Name      NULL            */
+#define SQLITE_DROP_INDEX           10   /* Index Name      Table Name      */
+#define SQLITE_DROP_TABLE           11   /* Table Name      NULL            */
+#define SQLITE_DROP_TEMP_INDEX      12   /* Index Name      Table Name      */
+#define SQLITE_DROP_TEMP_TABLE      13   /* Table Name      NULL            */
+#define SQLITE_DROP_TEMP_TRIGGER    14   /* Trigger Name    Table Name      */
+#define SQLITE_DROP_TEMP_VIEW       15   /* View Name       NULL            */
+#define SQLITE_DROP_TRIGGER         16   /* Trigger Name    Table Name      */
+#define SQLITE_DROP_VIEW            17   /* View Name       NULL            */
+#define SQLITE_INSERT               18   /* Table Name      NULL            */
+#define SQLITE_PRAGMA               19   /* Pragma Name     1st arg or NULL */
+#define SQLITE_READ                 20   /* Table Name      Column Name     */
+#define SQLITE_SELECT               21   /* NULL            NULL            */
+#define SQLITE_TRANSACTION          22   /* Operation       NULL            */
+#define SQLITE_UPDATE               23   /* Table Name      Column Name     */
+#define SQLITE_ATTACH               24   /* Filename        NULL            */
+#define SQLITE_DETACH               25   /* Database Name   NULL            */
+#define SQLITE_ALTER_TABLE          26   /* Database Name   Table Name      */
+#define SQLITE_REINDEX              27   /* Index Name      NULL            */
+#define SQLITE_ANALYZE              28   /* Table Name      NULL            */
+#define SQLITE_CREATE_VTABLE        29   /* Table Name      Module Name     */
+#define SQLITE_DROP_VTABLE          30   /* Table Name      Module Name     */
+#define SQLITE_FUNCTION             31   /* NULL            Function Name   */
+#define SQLITE_SAVEPOINT            32   /* Operation       Savepoint Name  */
+#define SQLITE_COPY                  0   /* No longer used */
+#define SQLITE_RECURSIVE            33   /* NULL            NULL            */
+
+/*
+** CAPI3REF: Tracing And Profiling Functions
+** METHOD: sqlite3
+**
+** These routines are deprecated. Use the [sqlite3_trace_v2()] interface
+** instead of the routines described here.
+**
+** These routines register callback functions that can be used for
+** tracing and profiling the execution of SQL statements.
+**
+** ^The callback function registered by sqlite3_trace() is invoked at
+** various times when an SQL statement is being run by [sqlite3_step()].
+** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
+** SQL statement text as the statement first begins executing.
+** ^(Additional sqlite3_trace() callbacks might occur
+** as each triggered subprogram is entered.  The callbacks for triggers
+** contain a UTF-8 SQL comment that identifies the trigger.)^
+**
+** The [SQLITE_TRACE_SIZE_LIMIT] compile-time option can be used to limit
+** the length of [bound parameter] expansion in the output of sqlite3_trace().
+**
+** ^The callback function registered by sqlite3_profile() is invoked
+** as each SQL statement finishes.  ^The profile callback contains
+** the original statement text and an estimate of wall-clock time
+** of how long that statement took to run.  ^The profile callback
+** time is in units of nanoseconds, however the current implementation
+** is only capable of millisecond resolution so the six least significant
+** digits in the time are meaningless.  Future versions of SQLite
+** might provide greater resolution on the profiler callback.  The
+** sqlite3_profile() function is considered experimental and is
+** subject to change in future versions of SQLite.
+*/
+SQLITE_API SQLITE_DEPRECATED void *sqlite3_trace(sqlite3*,
+   void(*xTrace)(void*,const char*), void*);
+SQLITE_API SQLITE_DEPRECATED void *sqlite3_profile(sqlite3*,
+   void(*xProfile)(void*,const char*,sqlite3_uint64), void*);
+
+/*
+** CAPI3REF: SQL Trace Event Codes
+** KEYWORDS: SQLITE_TRACE
+**
+** These constants identify classes of events that can be monitored
+** using the [sqlite3_trace_v2()] tracing logic.  The third argument
+** to [sqlite3_trace_v2()] is an OR-ed combination of one or more of
+** the following constants.  ^The first argument to the trace callback
+** is one of the following constants.
+**
+** New tracing constants may be added in future releases.
+**
+** ^A trace callback has four arguments: xCallback(T,C,P,X).
+** ^The T argument is one of the integer type codes above.
+** ^The C argument is a copy of the context pointer passed in as the
+** fourth argument to [sqlite3_trace_v2()].
+** The P and X arguments are pointers whose meanings depend on T.
+**
+** <dl>
+** [[SQLITE_TRACE_STMT]] <dt>SQLITE_TRACE_STMT</dt>
+** <dd>^An SQLITE_TRACE_STMT callback is invoked when a prepared statement
+** first begins running and possibly at other times during the
+** execution of the prepared statement, such as at the start of each
+** trigger subprogram. ^The P argument is a pointer to the
+** [prepared statement]. ^The X argument is a pointer to a string which
+** is the unexpanded SQL text of the prepared statement or an SQL comment 
+** that indicates the invocation of a trigger.  ^The callback can compute
+** the same text that would have been returned by the legacy [sqlite3_trace()]
+** interface by using the X argument when X begins with "--" and invoking
+** [sqlite3_expanded_sql(P)] otherwise.
+**
+** [[SQLITE_TRACE_PROFILE]] <dt>SQLITE_TRACE_PROFILE</dt>
+** <dd>^An SQLITE_TRACE_PROFILE callback provides approximately the same
+** information as is provided by the [sqlite3_profile()] callback.
+** ^The P argument is a pointer to the [prepared statement] and the
+** X argument points to a 64-bit integer which is the estimated of
+** the number of nanosecond that the prepared statement took to run.
+** ^The SQLITE_TRACE_PROFILE callback is invoked when the statement finishes.
+**
+** [[SQLITE_TRACE_ROW]] <dt>SQLITE_TRACE_ROW</dt>
+** <dd>^An SQLITE_TRACE_ROW callback is invoked whenever a prepared
+** statement generates a single row of result.  
+** ^The P argument is a pointer to the [prepared statement] and the
+** X argument is unused.
+**
+** [[SQLITE_TRACE_CLOSE]] <dt>SQLITE_TRACE_CLOSE</dt>
+** <dd>^An SQLITE_TRACE_CLOSE callback is invoked when a database
+** connection closes.
+** ^The P argument is a pointer to the [database connection] object
+** and the X argument is unused.
+** </dl>
+*/
+#define SQLITE_TRACE_STMT       0x01
+#define SQLITE_TRACE_PROFILE    0x02
+#define SQLITE_TRACE_ROW        0x04
+#define SQLITE_TRACE_CLOSE      0x08
+
+/*
+** CAPI3REF: SQL Trace Hook
+** METHOD: sqlite3
+**
+** ^The sqlite3_trace_v2(D,M,X,P) interface registers a trace callback
+** function X against [database connection] D, using property mask M
+** and context pointer P.  ^If the X callback is
+** NULL or if the M mask is zero, then tracing is disabled.  The
+** M argument should be the bitwise OR-ed combination of
+** zero or more [SQLITE_TRACE] constants.
+**
+** ^Each call to either sqlite3_trace() or sqlite3_trace_v2() overrides 
+** (cancels) any prior calls to sqlite3_trace() or sqlite3_trace_v2().
+**
+** ^The X callback is invoked whenever any of the events identified by 
+** mask M occur.  ^The integer return value from the callback is currently
+** ignored, though this may change in future releases.  Callback
+** implementations should return zero to ensure future compatibility.
+**
+** ^A trace callback is invoked with four arguments: callback(T,C,P,X).
+** ^The T argument is one of the [SQLITE_TRACE]
+** constants to indicate why the callback was invoked.
+** ^The C argument is a copy of the context pointer.
+** The P and X arguments are pointers whose meanings depend on T.
+**
+** The sqlite3_trace_v2() interface is intended to replace the legacy
+** interfaces [sqlite3_trace()] and [sqlite3_profile()], both of which
+** are deprecated.
+*/
+SQLITE_API int sqlite3_trace_v2(
+  sqlite3*,
+  unsigned uMask,
+  int(*xCallback)(unsigned,void*,void*,void*),
+  void *pCtx
+);
+
+/*
+** CAPI3REF: Query Progress Callbacks
+** METHOD: sqlite3
+**
+** ^The sqlite3_progress_handler(D,N,X,P) interface causes the callback
+** function X to be invoked periodically during long running calls to
+** [sqlite3_exec()], [sqlite3_step()] and [sqlite3_get_table()] for
+** database connection D.  An example use for this
+** interface is to keep a GUI updated during a large query.
+**
+** ^The parameter P is passed through as the only parameter to the 
+** callback function X.  ^The parameter N is the approximate number of 
+** [virtual machine instructions] that are evaluated between successive
+** invocations of the callback X.  ^If N is less than one then the progress
+** handler is disabled.
+**
+** ^Only a single progress handler may be defined at one time per
+** [database connection]; setting a new progress handler cancels the
+** old one.  ^Setting parameter X to NULL disables the progress handler.
+** ^The progress handler is also disabled by setting N to a value less
+** than 1.
+**
+** ^If the progress callback returns non-zero, the operation is
+** interrupted.  This feature can be used to implement a
+** "Cancel" button on a GUI progress dialog box.
+**
+** The progress handler callback must not do anything that will modify
+** the database connection that invoked the progress handler.
+** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
+** database connections for the meaning of "modify" in this paragraph.
+**
+*/
+SQLITE_API void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);
+
+/*
+** CAPI3REF: Opening A New Database Connection
+** CONSTRUCTOR: sqlite3
+**
+** ^These routines open an SQLite database file as specified by the 
+** filename argument. ^The filename argument is interpreted as UTF-8 for
+** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
+** order for sqlite3_open16(). ^(A [database connection] handle is usually
+** returned in *ppDb, even if an error occurs.  The only exception is that
+** if SQLite is unable to allocate memory to hold the [sqlite3] object,
+** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]
+** object.)^ ^(If the database is opened (and/or created) successfully, then
+** [SQLITE_OK] is returned.  Otherwise an [error code] is returned.)^ ^The
+** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain
+** an English language description of the error following a failure of any
+** of the sqlite3_open() routines.
+**
+** ^The default encoding will be UTF-8 for databases created using
+** sqlite3_open() or sqlite3_open_v2().  ^The default encoding for databases
+** created using sqlite3_open16() will be UTF-16 in the native byte order.
+**
+** Whether or not an error occurs when it is opened, resources
+** associated with the [database connection] handle should be released by
+** passing it to [sqlite3_close()] when it is no longer required.
+**
+** The sqlite3_open_v2() interface works like sqlite3_open()
+** except that it accepts two additional parameters for additional control
+** over the new database connection.  ^(The flags parameter to
+** sqlite3_open_v2() can take one of
+** the following three values, optionally combined with the 
+** [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX], [SQLITE_OPEN_SHAREDCACHE],
+** [SQLITE_OPEN_PRIVATECACHE], and/or [SQLITE_OPEN_URI] flags:)^
+**
+** <dl>
+** ^(<dt>[SQLITE_OPEN_READONLY]</dt>
+** <dd>The database is opened in read-only mode.  If the database does not
+** already exist, an error is returned.</dd>)^
+**
+** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>
+** <dd>The database is opened for reading and writing if possible, or reading
+** only if the file is write protected by the operating system.  In either
+** case the database must already exist, otherwise an error is returned.</dd>)^
+**
+** ^(<dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
+** <dd>The database is opened for reading and writing, and is created if
+** it does not already exist. This is the behavior that is always used for
+** sqlite3_open() and sqlite3_open16().</dd>)^
+** </dl>
+**
+** If the 3rd parameter to sqlite3_open_v2() is not one of the
+** combinations shown above optionally combined with other
+** [SQLITE_OPEN_READONLY | SQLITE_OPEN_* bits]
+** then the behavior is undefined.
+**
+** ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection
+** opens in the multi-thread [threading mode] as long as the single-thread
+** mode has not been set at compile-time or start-time.  ^If the
+** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens
+** in the serialized [threading mode] unless single-thread was
+** previously selected at compile-time or start-time.
+** ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be
+** eligible to use [shared cache mode], regardless of whether or not shared
+** cache is enabled using [sqlite3_enable_shared_cache()].  ^The
+** [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not
+** participate in [shared cache mode] even if it is enabled.
+**
+** ^The fourth parameter to sqlite3_open_v2() is the name of the
+** [sqlite3_vfs] object that defines the operating system interface that
+** the new database connection should use.  ^If the fourth parameter is
+** a NULL pointer then the default [sqlite3_vfs] object is used.
+**
+** ^If the filename is ":memory:", then a private, temporary in-memory database
+** is created for the connection.  ^This in-memory database will vanish when
+** the database connection is closed.  Future versions of SQLite might
+** make use of additional special filenames that begin with the ":" character.
+** It is recommended that when a database filename actually does begin with
+** a ":" character you should prefix the filename with a pathname such as
+** "./" to avoid ambiguity.
+**
+** ^If the filename is an empty string, then a private, temporary
+** on-disk database will be created.  ^This private database will be
+** automatically deleted as soon as the database connection is closed.
+**
+** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
+**
+** ^If [URI filename] interpretation is enabled, and the filename argument
+** begins with "file:", then the filename is interpreted as a URI. ^URI
+** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
+** set in the fourth argument to sqlite3_open_v2(), or if it has
+** been enabled globally using the [SQLITE_CONFIG_URI] option with the
+** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
+** As of SQLite version 3.7.7, URI filename interpretation is turned off
+** by default, but future releases of SQLite might enable URI filename
+** interpretation by default.  See "[URI filenames]" for additional
+** information.
+**
+** URI filenames are parsed according to RFC 3986. ^If the URI contains an
+** authority, then it must be either an empty string or the string 
+** "localhost". ^If the authority is not an empty string or "localhost", an 
+** error is returned to the caller. ^The fragment component of a URI, if 
+** present, is ignored.
+**
+** ^SQLite uses the path component of the URI as the name of the disk file
+** which contains the database. ^If the path begins with a '/' character, 
+** then it is interpreted as an absolute path. ^If the path does not begin 
+** with a '/' (meaning that the authority section is omitted from the URI)
+** then the path is interpreted as a relative path. 
+** ^(On windows, the first component of an absolute path 
+** is a drive specification (e.g. "C:").)^
+**
+** [[core URI query parameters]]
+** The query component of a URI may contain parameters that are interpreted
+** either by SQLite itself, or by a [VFS | custom VFS implementation].
+** SQLite and its built-in [VFSes] interpret the
+** following query parameters:
+**
+** <ul>
+**   <li> <b>vfs</b>: ^The "vfs" parameter may be used to specify the name of
+**     a VFS object that provides the operating system interface that should
+**     be used to access the database file on disk. ^If this option is set to
+**     an empty string the default VFS object is used. ^Specifying an unknown
+**     VFS is an error. ^If sqlite3_open_v2() is used and the vfs option is
+**     present, then the VFS specified by the option takes precedence over
+**     the value passed as the fourth parameter to sqlite3_open_v2().
+**
+**   <li> <b>mode</b>: ^(The mode parameter may be set to either "ro", "rw",
+**     "rwc", or "memory". Attempting to set it to any other value is
+**     an error)^. 
+**     ^If "ro" is specified, then the database is opened for read-only 
+**     access, just as if the [SQLITE_OPEN_READONLY] flag had been set in the 
+**     third argument to sqlite3_open_v2(). ^If the mode option is set to 
+**     "rw", then the database is opened for read-write (but not create) 
+**     access, as if SQLITE_OPEN_READWRITE (but not SQLITE_OPEN_CREATE) had 
+**     been set. ^Value "rwc" is equivalent to setting both 
+**     SQLITE_OPEN_READWRITE and SQLITE_OPEN_CREATE.  ^If the mode option is
+**     set to "memory" then a pure [in-memory database] that never reads
+**     or writes from disk is used. ^It is an error to specify a value for
+**     the mode parameter that is less restrictive than that specified by
+**     the flags passed in the third parameter to sqlite3_open_v2().
+**
+**   <li> <b>cache</b>: ^The cache parameter may be set to either "shared" or
+**     "private". ^Setting it to "shared" is equivalent to setting the
+**     SQLITE_OPEN_SHAREDCACHE bit in the flags argument passed to
+**     sqlite3_open_v2(). ^Setting the cache parameter to "private" is 
+**     equivalent to setting the SQLITE_OPEN_PRIVATECACHE bit.
+**     ^If sqlite3_open_v2() is used and the "cache" parameter is present in
+**     a URI filename, its value overrides any behavior requested by setting
+**     SQLITE_OPEN_PRIVATECACHE or SQLITE_OPEN_SHAREDCACHE flag.
+**
+**  <li> <b>psow</b>: ^The psow parameter indicates whether or not the
+**     [powersafe overwrite] property does or does not apply to the
+**     storage media on which the database file resides.
+**
+**  <li> <b>nolock</b>: ^The nolock parameter is a boolean query parameter
+**     which if set disables file locking in rollback journal modes.  This
+**     is useful for accessing a database on a filesystem that does not
+**     support locking.  Caution:  Database corruption might result if two
+**     or more processes write to the same database and any one of those
+**     processes uses nolock=1.
+**
+**  <li> <b>immutable</b>: ^The immutable parameter is a boolean query
+**     parameter that indicates that the database file is stored on
+**     read-only media.  ^When immutable is set, SQLite assumes that the
+**     database file cannot be changed, even by a process with higher
+**     privilege, and so the database is opened read-only and all locking
+**     and change detection is disabled.  Caution: Setting the immutable
+**     property on a database file that does in fact change can result
+**     in incorrect query results and/or [SQLITE_CORRUPT] errors.
+**     See also: [SQLITE_IOCAP_IMMUTABLE].
+**       
+** </ul>
+**
+** ^Specifying an unknown parameter in the query component of a URI is not an
+** error.  Future versions of SQLite might understand additional query
+** parameters.  See "[query parameters with special meaning to SQLite]" for
+** additional information.
+**
+** [[URI filename examples]] <h3>URI filename examples</h3>
+**
+** <table border="1" align=center cellpadding=5>
+** <tr><th> URI filenames <th> Results
+** <tr><td> file:data.db <td> 
+**          Open the file "data.db" in the current directory.
+** <tr><td> file:/home/fred/data.db<br>
+**          file:///home/fred/data.db <br> 
+**          file://localhost/home/fred/data.db <br> <td> 
+**          Open the database file "/home/fred/data.db".
+** <tr><td> file://darkstar/home/fred/data.db <td> 
+**          An error. "darkstar" is not a recognized authority.
+** <tr><td style="white-space:nowrap"> 
+**          file:///C:/Documents%20and%20Settings/fred/Desktop/data.db
+**     <td> Windows only: Open the file "data.db" on fred's desktop on drive
+**          C:. Note that the %20 escaping in this example is not strictly 
+**          necessary - space characters can be used literally
+**          in URI filenames.
+** <tr><td> file:data.db?mode=ro&cache=private <td> 
+**          Open file "data.db" in the current directory for read-only access.
+**          Regardless of whether or not shared-cache mode is enabled by
+**          default, use a private cache.
+** <tr><td> file:/home/fred/data.db?vfs=unix-dotfile <td>
+**          Open file "/home/fred/data.db". Use the special VFS "unix-dotfile"
+**          that uses dot-files in place of posix advisory locking.
+** <tr><td> file:data.db?mode=readonly <td> 
+**          An error. "readonly" is not a valid option for the "mode" parameter.
+** </table>
+**
+** ^URI hexadecimal escape sequences (%HH) are supported within the path and
+** query components of a URI. A hexadecimal escape sequence consists of a
+** percent sign - "%" - followed by exactly two hexadecimal digits 
+** specifying an octet value. ^Before the path or query components of a
+** URI filename are interpreted, they are encoded using UTF-8 and all 
+** hexadecimal escape sequences replaced by a single byte containing the
+** corresponding octet. If this process generates an invalid UTF-8 encoding,
+** the results are undefined.
+**
+** <b>Note to Windows users:</b>  The encoding used for the filename argument
+** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever
+** codepage is currently defined.  Filenames containing international
+** characters must be converted to UTF-8 prior to passing them into
+** sqlite3_open() or sqlite3_open_v2().
+**
+** <b>Note to Windows Runtime users:</b>  The temporary directory must be set
+** prior to calling sqlite3_open() or sqlite3_open_v2().  Otherwise, various
+** features that require the use of temporary files may fail.
+**
+** See also: [sqlite3_temp_directory]
+*/
+SQLITE_API int sqlite3_open(
+  const char *filename,   /* Database filename (UTF-8) */
+  sqlite3 **ppDb          /* OUT: SQLite db handle */
+);
+SQLITE_API int sqlite3_open16(
+  const void *filename,   /* Database filename (UTF-16) */
+  sqlite3 **ppDb          /* OUT: SQLite db handle */
+);
+SQLITE_API int sqlite3_open_v2(
+  const char *filename,   /* Database filename (UTF-8) */
+  sqlite3 **ppDb,         /* OUT: SQLite db handle */
+  int flags,              /* Flags */
+  const char *zVfs        /* Name of VFS module to use */
+);
+
+/*
+** CAPI3REF: Obtain Values For URI Parameters
+**
+** These are utility routines, useful to VFS implementations, that check
+** to see if a database file was a URI that contained a specific query 
+** parameter, and if so obtains the value of that query parameter.
+**
+** If F is the database filename pointer passed into the xOpen() method of 
+** a VFS implementation when the flags parameter to xOpen() has one or 
+** more of the [SQLITE_OPEN_URI] or [SQLITE_OPEN_MAIN_DB] bits set and
+** P is the name of the query parameter, then
+** sqlite3_uri_parameter(F,P) returns the value of the P
+** parameter if it exists or a NULL pointer if P does not appear as a 
+** query parameter on F.  If P is a query parameter of F
+** has no explicit value, then sqlite3_uri_parameter(F,P) returns
+** a pointer to an empty string.
+**
+** The sqlite3_uri_boolean(F,P,B) routine assumes that P is a boolean
+** parameter and returns true (1) or false (0) according to the value
+** of P.  The sqlite3_uri_boolean(F,P,B) routine returns true (1) if the
+** value of query parameter P is one of "yes", "true", or "on" in any
+** case or if the value begins with a non-zero number.  The 
+** sqlite3_uri_boolean(F,P,B) routines returns false (0) if the value of
+** query parameter P is one of "no", "false", or "off" in any case or
+** if the value begins with a numeric zero.  If P is not a query
+** parameter on F or if the value of P is does not match any of the
+** above, then sqlite3_uri_boolean(F,P,B) returns (B!=0).
+**
+** The sqlite3_uri_int64(F,P,D) routine converts the value of P into a
+** 64-bit signed integer and returns that integer, or D if P does not
+** exist.  If the value of P is something other than an integer, then
+** zero is returned.
+** 
+** If F is a NULL pointer, then sqlite3_uri_parameter(F,P) returns NULL and
+** sqlite3_uri_boolean(F,P,B) returns B.  If F is not a NULL pointer and
+** is not a database file pathname pointer that SQLite passed into the xOpen
+** VFS method, then the behavior of this routine is undefined and probably
+** undesirable.
+*/
+SQLITE_API const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam);
+SQLITE_API int sqlite3_uri_boolean(const char *zFile, const char *zParam, int bDefault);
+SQLITE_API sqlite3_int64 sqlite3_uri_int64(const char*, const char*, sqlite3_int64);
+
+
+/*
+** CAPI3REF: Error Codes And Messages
+** METHOD: sqlite3
+**
+** ^If the most recent sqlite3_* API call associated with 
+** [database connection] D failed, then the sqlite3_errcode(D) interface
+** returns the numeric [result code] or [extended result code] for that
+** API call.
+** If the most recent API call was successful,
+** then the return value from sqlite3_errcode() is undefined.
+** ^The sqlite3_extended_errcode()
+** interface is the same except that it always returns the 
+** [extended result code] even when extended result codes are
+** disabled.
+**
+** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
+** text that describes the error, as either UTF-8 or UTF-16 respectively.
+** ^(Memory to hold the error message string is managed internally.
+** The application does not need to worry about freeing the result.
+** However, the error string might be overwritten or deallocated by
+** subsequent calls to other SQLite interface functions.)^
+**
+** ^The sqlite3_errstr() interface returns the English-language text
+** that describes the [result code], as UTF-8.
+** ^(Memory to hold the error message string is managed internally
+** and must not be freed by the application)^.
+**
+** When the serialized [threading mode] is in use, it might be the
+** case that a second error occurs on a separate thread in between
+** the time of the first error and the call to these interfaces.
+** When that happens, the second error will be reported since these
+** interfaces always report the most recent result.  To avoid
+** this, each thread can obtain exclusive use of the [database connection] D
+** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
+** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
+** all calls to the interfaces listed here are completed.
+**
+** If an interface fails with SQLITE_MISUSE, that means the interface
+** was invoked incorrectly by the application.  In that case, the
+** error code and message may or may not be set.
+*/
+SQLITE_API int sqlite3_errcode(sqlite3 *db);
+SQLITE_API int sqlite3_extended_errcode(sqlite3 *db);
+SQLITE_API const char *sqlite3_errmsg(sqlite3*);
+SQLITE_API const void *sqlite3_errmsg16(sqlite3*);
+SQLITE_API const char *sqlite3_errstr(int);
+
+/*
+** CAPI3REF: Prepared Statement Object
+** KEYWORDS: {prepared statement} {prepared statements}
+**
+** An instance of this object represents a single SQL statement that
+** has been compiled into binary form and is ready to be evaluated.
+**
+** Think of each SQL statement as a separate computer program.  The
+** original SQL text is source code.  A prepared statement object 
+** is the compiled object code.  All SQL must be converted into a
+** prepared statement before it can be run.
+**
+** The life-cycle of a prepared statement object usually goes like this:
+**
+** <ol>
+** <li> Create the prepared statement object using [sqlite3_prepare_v2()].
+** <li> Bind values to [parameters] using the sqlite3_bind_*()
+**      interfaces.
+** <li> Run the SQL by calling [sqlite3_step()] one or more times.
+** <li> Reset the prepared statement using [sqlite3_reset()] then go back
+**      to step 2.  Do this zero or more times.
+** <li> Destroy the object using [sqlite3_finalize()].
+** </ol>
+*/
+typedef struct sqlite3_stmt sqlite3_stmt;
+
+/*
+** CAPI3REF: Run-time Limits
+** METHOD: sqlite3
+**
+** ^(This interface allows the size of various constructs to be limited
+** on a connection by connection basis.  The first parameter is the
+** [database connection] whose limit is to be set or queried.  The
+** second parameter is one of the [limit categories] that define a
+** class of constructs to be size limited.  The third parameter is the
+** new limit for that construct.)^
+**
+** ^If the new limit is a negative number, the limit is unchanged.
+** ^(For each limit category SQLITE_LIMIT_<i>NAME</i> there is a 
+** [limits | hard upper bound]
+** set at compile-time by a C preprocessor macro called
+** [limits | SQLITE_MAX_<i>NAME</i>].
+** (The "_LIMIT_" in the name is changed to "_MAX_".))^
+** ^Attempts to increase a limit above its hard upper bound are
+** silently truncated to the hard upper bound.
+**
+** ^Regardless of whether or not the limit was changed, the 
+** [sqlite3_limit()] interface returns the prior value of the limit.
+** ^Hence, to find the current value of a limit without changing it,
+** simply invoke this interface with the third parameter set to -1.
+**
+** Run-time limits are intended for use in applications that manage
+** both their own internal database and also databases that are controlled
+** by untrusted external sources.  An example application might be a
+** web browser that has its own databases for storing history and
+** separate databases controlled by JavaScript applications downloaded
+** off the Internet.  The internal databases can be given the
+** large, default limits.  Databases managed by external sources can
+** be given much smaller limits designed to prevent a denial of service
+** attack.  Developers might also want to use the [sqlite3_set_authorizer()]
+** interface to further control untrusted SQL.  The size of the database
+** created by an untrusted script can be contained using the
+** [max_page_count] [PRAGMA].
+**
+** New run-time limit categories may be added in future releases.
+*/
+SQLITE_API int sqlite3_limit(sqlite3*, int id, int newVal);
+
+/*
+** CAPI3REF: Run-Time Limit Categories
+** KEYWORDS: {limit category} {*limit categories}
+**
+** These constants define various performance limits
+** that can be lowered at run-time using [sqlite3_limit()].
+** The synopsis of the meanings of the various limits is shown below.
+** Additional information is available at [limits | Limits in SQLite].
+**
+** <dl>
+** [[SQLITE_LIMIT_LENGTH]] ^(<dt>SQLITE_LIMIT_LENGTH</dt>
+** <dd>The maximum size of any string or BLOB or table row, in bytes.<dd>)^
+**
+** [[SQLITE_LIMIT_SQL_LENGTH]] ^(<dt>SQLITE_LIMIT_SQL_LENGTH</dt>
+** <dd>The maximum length of an SQL statement, in bytes.</dd>)^
+**
+** [[SQLITE_LIMIT_COLUMN]] ^(<dt>SQLITE_LIMIT_COLUMN</dt>
+** <dd>The maximum number of columns in a table definition or in the
+** result set of a [SELECT] or the maximum number of columns in an index
+** or in an ORDER BY or GROUP BY clause.</dd>)^
+**
+** [[SQLITE_LIMIT_EXPR_DEPTH]] ^(<dt>SQLITE_LIMIT_EXPR_DEPTH</dt>
+** <dd>The maximum depth of the parse tree on any expression.</dd>)^
+**
+** [[SQLITE_LIMIT_COMPOUND_SELECT]] ^(<dt>SQLITE_LIMIT_COMPOUND_SELECT</dt>
+** <dd>The maximum number of terms in a compound SELECT statement.</dd>)^
+**
+** [[SQLITE_LIMIT_VDBE_OP]] ^(<dt>SQLITE_LIMIT_VDBE_OP</dt>
+** <dd>The maximum number of instructions in a virtual machine program
+** used to implement an SQL statement.  This limit is not currently
+** enforced, though that might be added in some future release of
+** SQLite.</dd>)^
+**
+** [[SQLITE_LIMIT_FUNCTION_ARG]] ^(<dt>SQLITE_LIMIT_FUNCTION_ARG</dt>
+** <dd>The maximum number of arguments on a function.</dd>)^
+**
+** [[SQLITE_LIMIT_ATTACHED]] ^(<dt>SQLITE_LIMIT_ATTACHED</dt>
+** <dd>The maximum number of [ATTACH | attached databases].)^</dd>
+**
+** [[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]]
+** ^(<dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt>
+** <dd>The maximum length of the pattern argument to the [LIKE] or
+** [GLOB] operators.</dd>)^
+**
+** [[SQLITE_LIMIT_VARIABLE_NUMBER]]
+** ^(<dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt>
+** <dd>The maximum index number of any [parameter] in an SQL statement.)^
+**
+** [[SQLITE_LIMIT_TRIGGER_DEPTH]] ^(<dt>SQLITE_LIMIT_TRIGGER_DEPTH</dt>
+** <dd>The maximum depth of recursion for triggers.</dd>)^
+**
+** [[SQLITE_LIMIT_WORKER_THREADS]] ^(<dt>SQLITE_LIMIT_WORKER_THREADS</dt>
+** <dd>The maximum number of auxiliary worker threads that a single
+** [prepared statement] may start.</dd>)^
+** </dl>
+*/
+#define SQLITE_LIMIT_LENGTH                    0
+#define SQLITE_LIMIT_SQL_LENGTH                1
+#define SQLITE_LIMIT_COLUMN                    2
+#define SQLITE_LIMIT_EXPR_DEPTH                3
+#define SQLITE_LIMIT_COMPOUND_SELECT           4
+#define SQLITE_LIMIT_VDBE_OP                   5
+#define SQLITE_LIMIT_FUNCTION_ARG              6
+#define SQLITE_LIMIT_ATTACHED                  7
+#define SQLITE_LIMIT_LIKE_PATTERN_LENGTH       8
+#define SQLITE_LIMIT_VARIABLE_NUMBER           9
+#define SQLITE_LIMIT_TRIGGER_DEPTH            10
+#define SQLITE_LIMIT_WORKER_THREADS           11
+
+/*
+** CAPI3REF: Compiling An SQL Statement
+** KEYWORDS: {SQL statement compiler}
+** METHOD: sqlite3
+** CONSTRUCTOR: sqlite3_stmt
+**
+** To execute an SQL query, it must first be compiled into a byte-code
+** program using one of these routines.
+**
+** The first argument, "db", is a [database connection] obtained from a
+** prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or
+** [sqlite3_open16()].  The database connection must not have been closed.
+**
+** The second argument, "zSql", is the statement to be compiled, encoded
+** as either UTF-8 or UTF-16.  The sqlite3_prepare() and sqlite3_prepare_v2()
+** interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2()
+** use UTF-16.
+**
+** ^If the nByte argument is negative, then zSql is read up to the
+** first zero terminator. ^If nByte is positive, then it is the
+** number of bytes read from zSql.  ^If nByte is zero, then no prepared
+** statement is generated.
+** If the caller knows that the supplied string is nul-terminated, then
+** there is a small performance advantage to passing an nByte parameter that
+** is the number of bytes in the input string <i>including</i>
+** the nul-terminator.
+**
+** ^If pzTail is not NULL then *pzTail is made to point to the first byte
+** past the end of the first SQL statement in zSql.  These routines only
+** compile the first statement in zSql, so *pzTail is left pointing to
+** what remains uncompiled.
+**
+** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
+** executed using [sqlite3_step()].  ^If there is an error, *ppStmt is set
+** to NULL.  ^If the input text contains no SQL (if the input is an empty
+** string or a comment) then *ppStmt is set to NULL.
+** The calling procedure is responsible for deleting the compiled
+** SQL statement using [sqlite3_finalize()] after it has finished with it.
+** ppStmt may not be NULL.
+**
+** ^On success, the sqlite3_prepare() family of routines return [SQLITE_OK];
+** otherwise an [error code] is returned.
+**
+** The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are
+** recommended for all new programs. The two older interfaces are retained
+** for backwards compatibility, but their use is discouraged.
+** ^In the "v2" interfaces, the prepared statement
+** that is returned (the [sqlite3_stmt] object) contains a copy of the
+** original SQL text. This causes the [sqlite3_step()] interface to
+** behave differently in three ways:
+**
+** <ol>
+** <li>
+** ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it
+** always used to do, [sqlite3_step()] will automatically recompile the SQL
+** statement and try to run it again. As many as [SQLITE_MAX_SCHEMA_RETRY]
+** retries will occur before sqlite3_step() gives up and returns an error.
+** </li>
+**
+** <li>
+** ^When an error occurs, [sqlite3_step()] will return one of the detailed
+** [error codes] or [extended error codes].  ^The legacy behavior was that
+** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code
+** and the application would have to make a second call to [sqlite3_reset()]
+** in order to find the underlying cause of the problem. With the "v2" prepare
+** interfaces, the underlying reason for the error is returned immediately.
+** </li>
+**
+** <li>
+** ^If the specific value bound to [parameter | host parameter] in the 
+** WHERE clause might influence the choice of query plan for a statement,
+** then the statement will be automatically recompiled, as if there had been 
+** a schema change, on the first  [sqlite3_step()] call following any change
+** to the [sqlite3_bind_text | bindings] of that [parameter]. 
+** ^The specific value of WHERE-clause [parameter] might influence the 
+** choice of query plan if the parameter is the left-hand side of a [LIKE]
+** or [GLOB] operator or if the parameter is compared to an indexed column
+** and the [SQLITE_ENABLE_STAT3] compile-time option is enabled.
+** </li>
+** </ol>
+*/
+SQLITE_API int sqlite3_prepare(
+  sqlite3 *db,            /* Database handle */
+  const char *zSql,       /* SQL statement, UTF-8 encoded */
+  int nByte,              /* Maximum length of zSql in bytes. */
+  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
+  const char **pzTail     /* OUT: Pointer to unused portion of zSql */
+);
+SQLITE_API int sqlite3_prepare_v2(
+  sqlite3 *db,            /* Database handle */
+  const char *zSql,       /* SQL statement, UTF-8 encoded */
+  int nByte,              /* Maximum length of zSql in bytes. */
+  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
+  const char **pzTail     /* OUT: Pointer to unused portion of zSql */
+);
+SQLITE_API int sqlite3_prepare16(
+  sqlite3 *db,            /* Database handle */
+  const void *zSql,       /* SQL statement, UTF-16 encoded */
+  int nByte,              /* Maximum length of zSql in bytes. */
+  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
+  const void **pzTail     /* OUT: Pointer to unused portion of zSql */
+);
+SQLITE_API int sqlite3_prepare16_v2(
+  sqlite3 *db,            /* Database handle */
+  const void *zSql,       /* SQL statement, UTF-16 encoded */
+  int nByte,              /* Maximum length of zSql in bytes. */
+  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
+  const void **pzTail     /* OUT: Pointer to unused portion of zSql */
+);
+
+/*
+** CAPI3REF: Retrieving Statement SQL
+** METHOD: sqlite3_stmt
+**
+** ^The sqlite3_sql(P) interface returns a pointer to a copy of the UTF-8
+** SQL text used to create [prepared statement] P if P was
+** created by either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
+** ^The sqlite3_expanded_sql(P) interface returns a pointer to a UTF-8
+** string containing the SQL text of prepared statement P with
+** [bound parameters] expanded.
+**
+** ^(For example, if a prepared statement is created using the SQL
+** text "SELECT $abc,:xyz" and if parameter $abc is bound to integer 2345
+** and parameter :xyz is unbound, then sqlite3_sql() will return
+** the original string, "SELECT $abc,:xyz" but sqlite3_expanded_sql()
+** will return "SELECT 2345,NULL".)^
+**
+** ^The sqlite3_expanded_sql() interface returns NULL if insufficient memory
+** is available to hold the result, or if the result would exceed the
+** the maximum string length determined by the [SQLITE_LIMIT_LENGTH].
+**
+** ^The [SQLITE_TRACE_SIZE_LIMIT] compile-time option limits the size of
+** bound parameter expansions.  ^The [SQLITE_OMIT_TRACE] compile-time
+** option causes sqlite3_expanded_sql() to always return NULL.
+**
+** ^The string returned by sqlite3_sql(P) is managed by SQLite and is
+** automatically freed when the prepared statement is finalized.
+** ^The string returned by sqlite3_expanded_sql(P), on the other hand,
+** is obtained from [sqlite3_malloc()] and must be free by the application
+** by passing it to [sqlite3_free()].
+*/
+SQLITE_API const char *sqlite3_sql(sqlite3_stmt *pStmt);
+SQLITE_API char *sqlite3_expanded_sql(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Determine If An SQL Statement Writes The Database
+** METHOD: sqlite3_stmt
+**
+** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if
+** and only if the [prepared statement] X makes no direct changes to
+** the content of the database file.
+**
+** Note that [application-defined SQL functions] or
+** [virtual tables] might change the database indirectly as a side effect.  
+** ^(For example, if an application defines a function "eval()" that 
+** calls [sqlite3_exec()], then the following SQL statement would
+** change the database file through side-effects:
+**
+** <blockquote><pre>
+**    SELECT eval('DELETE FROM t1') FROM t2;
+** </pre></blockquote>
+**
+** But because the [SELECT] statement does not change the database file
+** directly, sqlite3_stmt_readonly() would still return true.)^
+**
+** ^Transaction control statements such as [BEGIN], [COMMIT], [ROLLBACK],
+** [SAVEPOINT], and [RELEASE] cause sqlite3_stmt_readonly() to return true,
+** since the statements themselves do not actually modify the database but
+** rather they control the timing of when other statements modify the 
+** database.  ^The [ATTACH] and [DETACH] statements also cause
+** sqlite3_stmt_readonly() to return true since, while those statements
+** change the configuration of a database connection, they do not make 
+** changes to the content of the database files on disk.
+*/
+SQLITE_API int sqlite3_stmt_readonly(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Determine If A Prepared Statement Has Been Reset
+** METHOD: sqlite3_stmt
+**
+** ^The sqlite3_stmt_busy(S) interface returns true (non-zero) if the
+** [prepared statement] S has been stepped at least once using 
+** [sqlite3_step(S)] but has neither run to completion (returned
+** [SQLITE_DONE] from [sqlite3_step(S)]) nor
+** been reset using [sqlite3_reset(S)].  ^The sqlite3_stmt_busy(S)
+** interface returns false if S is a NULL pointer.  If S is not a 
+** NULL pointer and is not a pointer to a valid [prepared statement]
+** object, then the behavior is undefined and probably undesirable.
+**
+** This interface can be used in combination [sqlite3_next_stmt()]
+** to locate all prepared statements associated with a database 
+** connection that are in need of being reset.  This can be used,
+** for example, in diagnostic routines to search for prepared 
+** statements that are holding a transaction open.
+*/
+SQLITE_API int sqlite3_stmt_busy(sqlite3_stmt*);
+
+/*
+** CAPI3REF: Dynamically Typed Value Object
+** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value}
+**
+** SQLite uses the sqlite3_value object to represent all values
+** that can be stored in a database table. SQLite uses dynamic typing
+** for the values it stores.  ^Values stored in sqlite3_value objects
+** can be integers, floating point values, strings, BLOBs, or NULL.
+**
+** An sqlite3_value object may be either "protected" or "unprotected".
+** Some interfaces require a protected sqlite3_value.  Other interfaces
+** will accept either a protected or an unprotected sqlite3_value.
+** Every interface that accepts sqlite3_value arguments specifies
+** whether or not it requires a protected sqlite3_value.  The
+** [sqlite3_value_dup()] interface can be used to construct a new 
+** protected sqlite3_value from an unprotected sqlite3_value.
+**
+** The terms "protected" and "unprotected" refer to whether or not
+** a mutex is held.  An internal mutex is held for a protected
+** sqlite3_value object but no mutex is held for an unprotected
+** sqlite3_value object.  If SQLite is compiled to be single-threaded
+** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
+** or if SQLite is run in one of reduced mutex modes 
+** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
+** then there is no distinction between protected and unprotected
+** sqlite3_value objects and they can be used interchangeably.  However,
+** for maximum code portability it is recommended that applications
+** still make the distinction between protected and unprotected
+** sqlite3_value objects even when not strictly required.
+**
+** ^The sqlite3_value objects that are passed as parameters into the
+** implementation of [application-defined SQL functions] are protected.
+** ^The sqlite3_value object returned by
+** [sqlite3_column_value()] is unprotected.
+** Unprotected sqlite3_value objects may only be used with
+** [sqlite3_result_value()] and [sqlite3_bind_value()].
+** The [sqlite3_value_blob | sqlite3_value_type()] family of
+** interfaces require protected sqlite3_value objects.
+*/
+typedef struct Mem sqlite3_value;
+
+/*
+** CAPI3REF: SQL Function Context Object
+**
+** The context in which an SQL function executes is stored in an
+** sqlite3_context object.  ^A pointer to an sqlite3_context object
+** is always first parameter to [application-defined SQL functions].
+** The application-defined SQL function implementation will pass this
+** pointer through into calls to [sqlite3_result_int | sqlite3_result()],
+** [sqlite3_aggregate_context()], [sqlite3_user_data()],
+** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()],
+** and/or [sqlite3_set_auxdata()].
+*/
+typedef struct sqlite3_context sqlite3_context;
+
+/*
+** CAPI3REF: Binding Values To Prepared Statements
+** KEYWORDS: {host parameter} {host parameters} {host parameter name}
+** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding}
+** METHOD: sqlite3_stmt
+**
+** ^(In the SQL statement text input to [sqlite3_prepare_v2()] and its variants,
+** literals may be replaced by a [parameter] that matches one of following
+** templates:
+**
+** <ul>
+** <li>  ?
+** <li>  ?NNN
+** <li>  :VVV
+** <li>  @VVV
+** <li>  $VVV
+** </ul>
+**
+** In the templates above, NNN represents an integer literal,
+** and VVV represents an alphanumeric identifier.)^  ^The values of these
+** parameters (also called "host parameter names" or "SQL parameters")
+** can be set using the sqlite3_bind_*() routines defined here.
+**
+** ^The first argument to the sqlite3_bind_*() routines is always
+** a pointer to the [sqlite3_stmt] object returned from
+** [sqlite3_prepare_v2()] or its variants.
+**
+** ^The second argument is the index of the SQL parameter to be set.
+** ^The leftmost SQL parameter has an index of 1.  ^When the same named
+** SQL parameter is used more than once, second and subsequent
+** occurrences have the same index as the first occurrence.
+** ^The index for named parameters can be looked up using the
+** [sqlite3_bind_parameter_index()] API if desired.  ^The index
+** for "?NNN" parameters is the value of NNN.
+** ^The NNN value must be between 1 and the [sqlite3_limit()]
+** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999).
+**
+** ^The third argument is the value to bind to the parameter.
+** ^If the third parameter to sqlite3_bind_text() or sqlite3_bind_text16()
+** or sqlite3_bind_blob() is a NULL pointer then the fourth parameter
+** is ignored and the end result is the same as sqlite3_bind_null().
+**
+** ^(In those routines that have a fourth argument, its value is the
+** number of bytes in the parameter.  To be clear: the value is the
+** number of <u>bytes</u> in the value, not the number of characters.)^
+** ^If the fourth parameter to sqlite3_bind_text() or sqlite3_bind_text16()
+** is negative, then the length of the string is
+** the number of bytes up to the first zero terminator.
+** If the fourth parameter to sqlite3_bind_blob() is negative, then
+** the behavior is undefined.
+** If a non-negative fourth parameter is provided to sqlite3_bind_text()
+** or sqlite3_bind_text16() or sqlite3_bind_text64() then
+** that parameter must be the byte offset
+** where the NUL terminator would occur assuming the string were NUL
+** terminated.  If any NUL characters occur at byte offsets less than 
+** the value of the fourth parameter then the resulting string value will
+** contain embedded NULs.  The result of expressions involving strings
+** with embedded NULs is undefined.
+**
+** ^The fifth argument to the BLOB and string binding interfaces
+** is a destructor used to dispose of the BLOB or
+** string after SQLite has finished with it.  ^The destructor is called
+** to dispose of the BLOB or string even if the call to bind API fails.
+** ^If the fifth argument is
+** the special value [SQLITE_STATIC], then SQLite assumes that the
+** information is in static, unmanaged space and does not need to be freed.
+** ^If the fifth argument has the value [SQLITE_TRANSIENT], then
+** SQLite makes its own private copy of the data immediately, before
+** the sqlite3_bind_*() routine returns.
+**
+** ^The sixth argument to sqlite3_bind_text64() must be one of
+** [SQLITE_UTF8], [SQLITE_UTF16], [SQLITE_UTF16BE], or [SQLITE_UTF16LE]
+** to specify the encoding of the text in the third parameter.  If
+** the sixth argument to sqlite3_bind_text64() is not one of the
+** allowed values shown above, or if the text encoding is different
+** from the encoding specified by the sixth parameter, then the behavior
+** is undefined.
+**
+** ^The sqlite3_bind_zeroblob() routine binds a BLOB of length N that
+** is filled with zeroes.  ^A zeroblob uses a fixed amount of memory
+** (just an integer to hold its size) while it is being processed.
+** Zeroblobs are intended to serve as placeholders for BLOBs whose
+** content is later written using
+** [sqlite3_blob_open | incremental BLOB I/O] routines.
+** ^A negative value for the zeroblob results in a zero-length BLOB.
+**
+** ^If any of the sqlite3_bind_*() routines are called with a NULL pointer
+** for the [prepared statement] or with a prepared statement for which
+** [sqlite3_step()] has been called more recently than [sqlite3_reset()],
+** then the call will return [SQLITE_MISUSE].  If any sqlite3_bind_()
+** routine is passed a [prepared statement] that has been finalized, the
+** result is undefined and probably harmful.
+**
+** ^Bindings are not cleared by the [sqlite3_reset()] routine.
+** ^Unbound parameters are interpreted as NULL.
+**
+** ^The sqlite3_bind_* routines return [SQLITE_OK] on success or an
+** [error code] if anything goes wrong.
+** ^[SQLITE_TOOBIG] might be returned if the size of a string or BLOB
+** exceeds limits imposed by [sqlite3_limit]([SQLITE_LIMIT_LENGTH]) or
+** [SQLITE_MAX_LENGTH].
+** ^[SQLITE_RANGE] is returned if the parameter
+** index is out of range.  ^[SQLITE_NOMEM] is returned if malloc() fails.
+**
+** See also: [sqlite3_bind_parameter_count()],
+** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()].
+*/
+SQLITE_API int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*));
+SQLITE_API int sqlite3_bind_blob64(sqlite3_stmt*, int, const void*, sqlite3_uint64,
+                        void(*)(void*));
+SQLITE_API int sqlite3_bind_double(sqlite3_stmt*, int, double);
+SQLITE_API int sqlite3_bind_int(sqlite3_stmt*, int, int);
+SQLITE_API int sqlite3_bind_int64(sqlite3_stmt*, int, sqlite3_int64);
+SQLITE_API int sqlite3_bind_null(sqlite3_stmt*, int);
+SQLITE_API int sqlite3_bind_text(sqlite3_stmt*,int,const char*,int,void(*)(void*));
+SQLITE_API int sqlite3_bind_text16(sqlite3_stmt*, int, const void*, int, void(*)(void*));
+SQLITE_API int sqlite3_bind_text64(sqlite3_stmt*, int, const char*, sqlite3_uint64,
+                         void(*)(void*), unsigned char encoding);
+SQLITE_API int sqlite3_bind_value(sqlite3_stmt*, int, const sqlite3_value*);
+SQLITE_API int sqlite3_bind_zeroblob(sqlite3_stmt*, int, int n);
+SQLITE_API int sqlite3_bind_zeroblob64(sqlite3_stmt*, int, sqlite3_uint64);
+
+/*
+** CAPI3REF: Number Of SQL Parameters
+** METHOD: sqlite3_stmt
+**
+** ^This routine can be used to find the number of [SQL parameters]
+** in a [prepared statement].  SQL parameters are tokens of the
+** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as
+** placeholders for values that are [sqlite3_bind_blob | bound]
+** to the parameters at a later time.
+**
+** ^(This routine actually returns the index of the largest (rightmost)
+** parameter. For all forms except ?NNN, this will correspond to the
+** number of unique parameters.  If parameters of the ?NNN form are used,
+** there may be gaps in the list.)^
+**
+** See also: [sqlite3_bind_blob|sqlite3_bind()],
+** [sqlite3_bind_parameter_name()], and
+** [sqlite3_bind_parameter_index()].
+*/
+SQLITE_API int sqlite3_bind_parameter_count(sqlite3_stmt*);
+
+/*
+** CAPI3REF: Name Of A Host Parameter
+** METHOD: sqlite3_stmt
+**
+** ^The sqlite3_bind_parameter_name(P,N) interface returns
+** the name of the N-th [SQL parameter] in the [prepared statement] P.
+** ^(SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA"
+** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA"
+** respectively.
+** In other words, the initial ":" or "$" or "@" or "?"
+** is included as part of the name.)^
+** ^Parameters of the form "?" without a following integer have no name
+** and are referred to as "nameless" or "anonymous parameters".
+**
+** ^The first host parameter has an index of 1, not 0.
+**
+** ^If the value N is out of range or if the N-th parameter is
+** nameless, then NULL is returned.  ^The returned string is
+** always in UTF-8 encoding even if the named parameter was
+** originally specified as UTF-16 in [sqlite3_prepare16()] or
+** [sqlite3_prepare16_v2()].
+**
+** See also: [sqlite3_bind_blob|sqlite3_bind()],
+** [sqlite3_bind_parameter_count()], and
+** [sqlite3_bind_parameter_index()].
+*/
+SQLITE_API const char *sqlite3_bind_parameter_name(sqlite3_stmt*, int);
+
+/*
+** CAPI3REF: Index Of A Parameter With A Given Name
+** METHOD: sqlite3_stmt
+**
+** ^Return the index of an SQL parameter given its name.  ^The
+** index value returned is suitable for use as the second
+** parameter to [sqlite3_bind_blob|sqlite3_bind()].  ^A zero
+** is returned if no matching parameter is found.  ^The parameter
+** name must be given in UTF-8 even if the original statement
+** was prepared from UTF-16 text using [sqlite3_prepare16_v2()].
+**
+** See also: [sqlite3_bind_blob|sqlite3_bind()],
+** [sqlite3_bind_parameter_count()], and
+** [sqlite3_bind_parameter_name()].
+*/
+SQLITE_API int sqlite3_bind_parameter_index(sqlite3_stmt*, const char *zName);
+
+/*
+** CAPI3REF: Reset All Bindings On A Prepared Statement
+** METHOD: sqlite3_stmt
+**
+** ^Contrary to the intuition of many, [sqlite3_reset()] does not reset
+** the [sqlite3_bind_blob | bindings] on a [prepared statement].
+** ^Use this routine to reset all host parameters to NULL.
+*/
+SQLITE_API int sqlite3_clear_bindings(sqlite3_stmt*);
+
+/*
+** CAPI3REF: Number Of Columns In A Result Set
+** METHOD: sqlite3_stmt
+**
+** ^Return the number of columns in the result set returned by the
+** [prepared statement]. ^This routine returns 0 if pStmt is an SQL
+** statement that does not return data (for example an [UPDATE]).
+**
+** See also: [sqlite3_data_count()]
+*/
+SQLITE_API int sqlite3_column_count(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Column Names In A Result Set
+** METHOD: sqlite3_stmt
+**
+** ^These routines return the name assigned to a particular column
+** in the result set of a [SELECT] statement.  ^The sqlite3_column_name()
+** interface returns a pointer to a zero-terminated UTF-8 string
+** and sqlite3_column_name16() returns a pointer to a zero-terminated
+** UTF-16 string.  ^The first parameter is the [prepared statement]
+** that implements the [SELECT] statement. ^The second parameter is the
+** column number.  ^The leftmost column is number 0.
+**
+** ^The returned string pointer is valid until either the [prepared statement]
+** is destroyed by [sqlite3_finalize()] or until the statement is automatically
+** reprepared by the first call to [sqlite3_step()] for a particular run
+** or until the next call to
+** sqlite3_column_name() or sqlite3_column_name16() on the same column.
+**
+** ^If sqlite3_malloc() fails during the processing of either routine
+** (for example during a conversion from UTF-8 to UTF-16) then a
+** NULL pointer is returned.
+**
+** ^The name of a result column is the value of the "AS" clause for
+** that column, if there is an AS clause.  If there is no AS clause
+** then the name of the column is unspecified and may change from
+** one release of SQLite to the next.
+*/
+SQLITE_API const char *sqlite3_column_name(sqlite3_stmt*, int N);
+SQLITE_API const void *sqlite3_column_name16(sqlite3_stmt*, int N);
+
+/*
+** CAPI3REF: Source Of Data In A Query Result
+** METHOD: sqlite3_stmt
+**
+** ^These routines provide a means to determine the database, table, and
+** table column that is the origin of a particular result column in
+** [SELECT] statement.
+** ^The name of the database or table or column can be returned as
+** either a UTF-8 or UTF-16 string.  ^The _database_ routines return
+** the database name, the _table_ routines return the table name, and
+** the origin_ routines return the column name.
+** ^The returned string is valid until the [prepared statement] is destroyed
+** using [sqlite3_finalize()] or until the statement is automatically
+** reprepared by the first call to [sqlite3_step()] for a particular run
+** or until the same information is requested
+** again in a different encoding.
+**
+** ^The names returned are the original un-aliased names of the
+** database, table, and column.
+**
+** ^The first argument to these interfaces is a [prepared statement].
+** ^These functions return information about the Nth result column returned by
+** the statement, where N is the second function argument.
+** ^The left-most column is column 0 for these routines.
+**
+** ^If the Nth column returned by the statement is an expression or
+** subquery and is not a column value, then all of these functions return
+** NULL.  ^These routine might also return NULL if a memory allocation error
+** occurs.  ^Otherwise, they return the name of the attached database, table,
+** or column that query result column was extracted from.
+**
+** ^As with all other SQLite APIs, those whose names end with "16" return
+** UTF-16 encoded strings and the other functions return UTF-8.
+**
+** ^These APIs are only available if the library was compiled with the
+** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol.
+**
+** If two or more threads call one or more of these routines against the same
+** prepared statement and column at the same time then the results are
+** undefined.
+**
+** If two or more threads call one or more
+** [sqlite3_column_database_name | column metadata interfaces]
+** for the same [prepared statement] and result column
+** at the same time then the results are undefined.
+*/
+SQLITE_API const char *sqlite3_column_database_name(sqlite3_stmt*,int);
+SQLITE_API const void *sqlite3_column_database_name16(sqlite3_stmt*,int);
+SQLITE_API const char *sqlite3_column_table_name(sqlite3_stmt*,int);
+SQLITE_API const void *sqlite3_column_table_name16(sqlite3_stmt*,int);
+SQLITE_API const char *sqlite3_column_origin_name(sqlite3_stmt*,int);
+SQLITE_API const void *sqlite3_column_origin_name16(sqlite3_stmt*,int);
+
+/*
+** CAPI3REF: Declared Datatype Of A Query Result
+** METHOD: sqlite3_stmt
+**
+** ^(The first parameter is a [prepared statement].
+** If this statement is a [SELECT] statement and the Nth column of the
+** returned result set of that [SELECT] is a table column (not an
+** expression or subquery) then the declared type of the table
+** column is returned.)^  ^If the Nth column of the result set is an
+** expression or subquery, then a NULL pointer is returned.
+** ^The returned string is always UTF-8 encoded.
+**
+** ^(For example, given the database schema:
+**
+** CREATE TABLE t1(c1 VARIANT);
+**
+** and the following statement to be compiled:
+**
+** SELECT c1 + 1, c1 FROM t1;
+**
+** this routine would return the string "VARIANT" for the second result
+** column (i==1), and a NULL pointer for the first result column (i==0).)^
+**
+** ^SQLite uses dynamic run-time typing.  ^So just because a column
+** is declared to contain a particular type does not mean that the
+** data stored in that column is of the declared type.  SQLite is
+** strongly typed, but the typing is dynamic not static.  ^Type
+** is associated with individual values, not with the containers
+** used to hold those values.
+*/
+SQLITE_API const char *sqlite3_column_decltype(sqlite3_stmt*,int);
+SQLITE_API const void *sqlite3_column_decltype16(sqlite3_stmt*,int);
+
+/*
+** CAPI3REF: Evaluate An SQL Statement
+** METHOD: sqlite3_stmt
+**
+** After a [prepared statement] has been prepared using either
+** [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] or one of the legacy
+** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function
+** must be called one or more times to evaluate the statement.
+**
+** The details of the behavior of the sqlite3_step() interface depend
+** on whether the statement was prepared using the newer "v2" interface
+** [sqlite3_prepare_v2()] and [sqlite3_prepare16_v2()] or the older legacy
+** interface [sqlite3_prepare()] and [sqlite3_prepare16()].  The use of the
+** new "v2" interface is recommended for new applications but the legacy
+** interface will continue to be supported.
+**
+** ^In the legacy interface, the return value will be either [SQLITE_BUSY],
+** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
+** ^With the "v2" interface, any of the other [result codes] or
+** [extended result codes] might be returned as well.
+**
+** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
+** database locks it needs to do its job.  ^If the statement is a [COMMIT]
+** or occurs outside of an explicit transaction, then you can retry the
+** statement.  If the statement is not a [COMMIT] and occurs within an
+** explicit transaction then you should rollback the transaction before
+** continuing.
+**
+** ^[SQLITE_DONE] means that the statement has finished executing
+** successfully.  sqlite3_step() should not be called again on this virtual
+** machine without first calling [sqlite3_reset()] to reset the virtual
+** machine back to its initial state.
+**
+** ^If the SQL statement being executed returns any data, then [SQLITE_ROW]
+** is returned each time a new row of data is ready for processing by the
+** caller. The values may be accessed using the [column access functions].
+** sqlite3_step() is called again to retrieve the next row of data.
+**
+** ^[SQLITE_ERROR] means that a run-time error (such as a constraint
+** violation) has occurred.  sqlite3_step() should not be called again on
+** the VM. More information may be found by calling [sqlite3_errmsg()].
+** ^With the legacy interface, a more specific error code (for example,
+** [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth)
+** can be obtained by calling [sqlite3_reset()] on the
+** [prepared statement].  ^In the "v2" interface,
+** the more specific error code is returned directly by sqlite3_step().
+**
+** [SQLITE_MISUSE] means that the this routine was called inappropriately.
+** Perhaps it was called on a [prepared statement] that has
+** already been [sqlite3_finalize | finalized] or on one that had
+** previously returned [SQLITE_ERROR] or [SQLITE_DONE].  Or it could
+** be the case that the same database connection is being used by two or
+** more threads at the same moment in time.
+**
+** For all versions of SQLite up to and including 3.6.23.1, a call to
+** [sqlite3_reset()] was required after sqlite3_step() returned anything
+** other than [SQLITE_ROW] before any subsequent invocation of
+** sqlite3_step().  Failure to reset the prepared statement using 
+** [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from
+** sqlite3_step().  But after [version 3.6.23.1] ([dateof:3.6.23.1],
+** sqlite3_step() began
+** calling [sqlite3_reset()] automatically in this circumstance rather
+** than returning [SQLITE_MISUSE].  This is not considered a compatibility
+** break because any application that ever receives an SQLITE_MISUSE error
+** is broken by definition.  The [SQLITE_OMIT_AUTORESET] compile-time option
+** can be used to restore the legacy behavior.
+**
+** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
+** API always returns a generic error code, [SQLITE_ERROR], following any
+** error other than [SQLITE_BUSY] and [SQLITE_MISUSE].  You must call
+** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
+** specific [error codes] that better describes the error.
+** We admit that this is a goofy design.  The problem has been fixed
+** with the "v2" interface.  If you prepare all of your SQL statements
+** using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead
+** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,
+** then the more specific [error codes] are returned directly
+** by sqlite3_step().  The use of the "v2" interface is recommended.
+*/
+SQLITE_API int sqlite3_step(sqlite3_stmt*);
+
+/*
+** CAPI3REF: Number of columns in a result set
+** METHOD: sqlite3_stmt
+**
+** ^The sqlite3_data_count(P) interface returns the number of columns in the
+** current row of the result set of [prepared statement] P.
+** ^If prepared statement P does not have results ready to return
+** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
+** interfaces) then sqlite3_data_count(P) returns 0.
+** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.
+** ^The sqlite3_data_count(P) routine returns 0 if the previous call to
+** [sqlite3_step](P) returned [SQLITE_DONE].  ^The sqlite3_data_count(P)
+** will return non-zero if previous call to [sqlite3_step](P) returned
+** [SQLITE_ROW], except in the case of the [PRAGMA incremental_vacuum]
+** where it always returns zero since each step of that multi-step
+** pragma returns 0 columns of data.
+**
+** See also: [sqlite3_column_count()]
+*/
+SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Fundamental Datatypes
+** KEYWORDS: SQLITE_TEXT
+**
+** ^(Every value in SQLite has one of five fundamental datatypes:
+**
+** <ul>
+** <li> 64-bit signed integer
+** <li> 64-bit IEEE floating point number
+** <li> string
+** <li> BLOB
+** <li> NULL
+** </ul>)^
+**
+** These constants are codes for each of those types.
+**
+** Note that the SQLITE_TEXT constant was also used in SQLite version 2
+** for a completely different meaning.  Software that links against both
+** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not
+** SQLITE_TEXT.
+*/
+#define SQLITE_INTEGER  1
+#define SQLITE_FLOAT    2
+#define SQLITE_BLOB     4
+#define SQLITE_NULL     5
+#ifdef SQLITE_TEXT
+# undef SQLITE_TEXT
+#else
+# define SQLITE_TEXT     3
+#endif
+#define SQLITE3_TEXT     3
+
+/*
+** CAPI3REF: Result Values From A Query
+** KEYWORDS: {column access functions}
+** METHOD: sqlite3_stmt
+**
+** ^These routines return information about a single column of the current
+** result row of a query.  ^In every case the first argument is a pointer
+** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*]
+** that was returned from [sqlite3_prepare_v2()] or one of its variants)
+** and the second argument is the index of the column for which information
+** should be returned. ^The leftmost column of the result set has the index 0.
+** ^The number of columns in the result can be determined using
+** [sqlite3_column_count()].
+**
+** If the SQL statement does not currently point to a valid row, or if the
+** column index is out of range, the result is undefined.
+** These routines may only be called when the most recent call to
+** [sqlite3_step()] has returned [SQLITE_ROW] and neither
+** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently.
+** If any of these routines are called after [sqlite3_reset()] or
+** [sqlite3_finalize()] or after [sqlite3_step()] has returned
+** something other than [SQLITE_ROW], the results are undefined.
+** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()]
+** are called from a different thread while any of these routines
+** are pending, then the results are undefined.
+**
+** ^The sqlite3_column_type() routine returns the
+** [SQLITE_INTEGER | datatype code] for the initial data type
+** of the result column.  ^The returned value is one of [SQLITE_INTEGER],
+** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL].  The value
+** returned by sqlite3_column_type() is only meaningful if no type
+** conversions have occurred as described below.  After a type conversion,
+** the value returned by sqlite3_column_type() is undefined.  Future
+** versions of SQLite may change the behavior of sqlite3_column_type()
+** following a type conversion.
+**
+** ^If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes()
+** routine returns the number of bytes in that BLOB or string.
+** ^If the result is a UTF-16 string, then sqlite3_column_bytes() converts
+** the string to UTF-8 and then returns the number of bytes.
+** ^If the result is a numeric value then sqlite3_column_bytes() uses
+** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns
+** the number of bytes in that string.
+** ^If the result is NULL, then sqlite3_column_bytes() returns zero.
+**
+** ^If the result is a BLOB or UTF-16 string then the sqlite3_column_bytes16()
+** routine returns the number of bytes in that BLOB or string.
+** ^If the result is a UTF-8 string, then sqlite3_column_bytes16() converts
+** the string to UTF-16 and then returns the number of bytes.
+** ^If the result is a numeric value then sqlite3_column_bytes16() uses
+** [sqlite3_snprintf()] to convert that value to a UTF-16 string and returns
+** the number of bytes in that string.
+** ^If the result is NULL, then sqlite3_column_bytes16() returns zero.
+**
+** ^The values returned by [sqlite3_column_bytes()] and 
+** [sqlite3_column_bytes16()] do not include the zero terminators at the end
+** of the string.  ^For clarity: the values returned by
+** [sqlite3_column_bytes()] and [sqlite3_column_bytes16()] are the number of
+** bytes in the string, not the number of characters.
+**
+** ^Strings returned by sqlite3_column_text() and sqlite3_column_text16(),
+** even empty strings, are always zero-terminated.  ^The return
+** value from sqlite3_column_blob() for a zero-length BLOB is a NULL pointer.
+**
+** <b>Warning:</b> ^The object returned by [sqlite3_column_value()] is an
+** [unprotected sqlite3_value] object.  In a multithreaded environment,
+** an unprotected sqlite3_value object may only be used safely with
+** [sqlite3_bind_value()] and [sqlite3_result_value()].
+** If the [unprotected sqlite3_value] object returned by
+** [sqlite3_column_value()] is used in any other way, including calls
+** to routines like [sqlite3_value_int()], [sqlite3_value_text()],
+** or [sqlite3_value_bytes()], the behavior is not threadsafe.
+**
+** These routines attempt to convert the value where appropriate.  ^For
+** example, if the internal representation is FLOAT and a text result
+** is requested, [sqlite3_snprintf()] is used internally to perform the
+** conversion automatically.  ^(The following table details the conversions
+** that are applied:
+**
+** <blockquote>
+** <table border="1">
+** <tr><th> Internal<br>Type <th> Requested<br>Type <th>  Conversion
+**
+** <tr><td>  NULL    <td> INTEGER   <td> Result is 0
+** <tr><td>  NULL    <td>  FLOAT    <td> Result is 0.0
+** <tr><td>  NULL    <td>   TEXT    <td> Result is a NULL pointer
+** <tr><td>  NULL    <td>   BLOB    <td> Result is a NULL pointer
+** <tr><td> INTEGER  <td>  FLOAT    <td> Convert from integer to float
+** <tr><td> INTEGER  <td>   TEXT    <td> ASCII rendering of the integer
+** <tr><td> INTEGER  <td>   BLOB    <td> Same as INTEGER->TEXT
+** <tr><td>  FLOAT   <td> INTEGER   <td> [CAST] to INTEGER
+** <tr><td>  FLOAT   <td>   TEXT    <td> ASCII rendering of the float
+** <tr><td>  FLOAT   <td>   BLOB    <td> [CAST] to BLOB
+** <tr><td>  TEXT    <td> INTEGER   <td> [CAST] to INTEGER
+** <tr><td>  TEXT    <td>  FLOAT    <td> [CAST] to REAL
+** <tr><td>  TEXT    <td>   BLOB    <td> No change
+** <tr><td>  BLOB    <td> INTEGER   <td> [CAST] to INTEGER
+** <tr><td>  BLOB    <td>  FLOAT    <td> [CAST] to REAL
+** <tr><td>  BLOB    <td>   TEXT    <td> Add a zero terminator if needed
+** </table>
+** </blockquote>)^
+**
+** Note that when type conversions occur, pointers returned by prior
+** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or
+** sqlite3_column_text16() may be invalidated.
+** Type conversions and pointer invalidations might occur
+** in the following cases:
+**
+** <ul>
+** <li> The initial content is a BLOB and sqlite3_column_text() or
+**      sqlite3_column_text16() is called.  A zero-terminator might
+**      need to be added to the string.</li>
+** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or
+**      sqlite3_column_text16() is called.  The content must be converted
+**      to UTF-16.</li>
+** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or
+**      sqlite3_column_text() is called.  The content must be converted
+**      to UTF-8.</li>
+** </ul>
+**
+** ^Conversions between UTF-16be and UTF-16le are always done in place and do
+** not invalidate a prior pointer, though of course the content of the buffer
+** that the prior pointer references will have been modified.  Other kinds
+** of conversion are done in place when it is possible, but sometimes they
+** are not possible and in those cases prior pointers are invalidated.
+**
+** The safest policy is to invoke these routines
+** in one of the following ways:
+**
+** <ul>
+**  <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li>
+**  <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li>
+**  <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li>
+** </ul>
+**
+** In other words, you should call sqlite3_column_text(),
+** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result
+** into the desired format, then invoke sqlite3_column_bytes() or
+** sqlite3_column_bytes16() to find the size of the result.  Do not mix calls
+** to sqlite3_column_text() or sqlite3_column_blob() with calls to
+** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16()
+** with calls to sqlite3_column_bytes().
+**
+** ^The pointers returned are valid until a type conversion occurs as
+** described above, or until [sqlite3_step()] or [sqlite3_reset()] or
+** [sqlite3_finalize()] is called.  ^The memory space used to hold strings
+** and BLOBs is freed automatically.  Do <em>not</em> pass the pointers returned
+** from [sqlite3_column_blob()], [sqlite3_column_text()], etc. into
+** [sqlite3_free()].
+**
+** ^(If a memory allocation error occurs during the evaluation of any
+** of these routines, a default value is returned.  The default value
+** is either the integer 0, the floating point number 0.0, or a NULL
+** pointer.  Subsequent calls to [sqlite3_errcode()] will return
+** [SQLITE_NOMEM].)^
+*/
+SQLITE_API const void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
+SQLITE_API int sqlite3_column_bytes(sqlite3_stmt*, int iCol);
+SQLITE_API int sqlite3_column_bytes16(sqlite3_stmt*, int iCol);
+SQLITE_API double sqlite3_column_double(sqlite3_stmt*, int iCol);
+SQLITE_API int sqlite3_column_int(sqlite3_stmt*, int iCol);
+SQLITE_API sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);
+SQLITE_API const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol);
+SQLITE_API const void *sqlite3_column_text16(sqlite3_stmt*, int iCol);
+SQLITE_API int sqlite3_column_type(sqlite3_stmt*, int iCol);
+SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);
+
+/*
+** CAPI3REF: Destroy A Prepared Statement Object
+** DESTRUCTOR: sqlite3_stmt
+**
+** ^The sqlite3_finalize() function is called to delete a [prepared statement].
+** ^If the most recent evaluation of the statement encountered no errors
+** or if the statement is never been evaluated, then sqlite3_finalize() returns
+** SQLITE_OK.  ^If the most recent evaluation of statement S failed, then
+** sqlite3_finalize(S) returns the appropriate [error code] or
+** [extended error code].
+**
+** ^The sqlite3_finalize(S) routine can be called at any point during
+** the life cycle of [prepared statement] S:
+** before statement S is ever evaluated, after
+** one or more calls to [sqlite3_reset()], or after any call
+** to [sqlite3_step()] regardless of whether or not the statement has
+** completed execution.
+**
+** ^Invoking sqlite3_finalize() on a NULL pointer is a harmless no-op.
+**
+** The application must finalize every [prepared statement] in order to avoid
+** resource leaks.  It is a grievous error for the application to try to use
+** a prepared statement after it has been finalized.  Any use of a prepared
+** statement after it has been finalized can result in undefined and
+** undesirable behavior such as segfaults and heap corruption.
+*/
+SQLITE_API int sqlite3_finalize(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Reset A Prepared Statement Object
+** METHOD: sqlite3_stmt
+**
+** The sqlite3_reset() function is called to reset a [prepared statement]
+** object back to its initial state, ready to be re-executed.
+** ^Any SQL statement variables that had values bound to them using
+** the [sqlite3_bind_blob | sqlite3_bind_*() API] retain their values.
+** Use [sqlite3_clear_bindings()] to reset the bindings.
+**
+** ^The [sqlite3_reset(S)] interface resets the [prepared statement] S
+** back to the beginning of its program.
+**
+** ^If the most recent call to [sqlite3_step(S)] for the
+** [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE],
+** or if [sqlite3_step(S)] has never before been called on S,
+** then [sqlite3_reset(S)] returns [SQLITE_OK].
+**
+** ^If the most recent call to [sqlite3_step(S)] for the
+** [prepared statement] S indicated an error, then
+** [sqlite3_reset(S)] returns an appropriate [error code].
+**
+** ^The [sqlite3_reset(S)] interface does not change the values
+** of any [sqlite3_bind_blob|bindings] on the [prepared statement] S.
+*/
+SQLITE_API int sqlite3_reset(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Create Or Redefine SQL Functions
+** KEYWORDS: {function creation routines}
+** KEYWORDS: {application-defined SQL function}
+** KEYWORDS: {application-defined SQL functions}
+** METHOD: sqlite3
+**
+** ^These functions (collectively known as "function creation routines")
+** are used to add SQL functions or aggregates or to redefine the behavior
+** of existing SQL functions or aggregates.  The only differences between
+** these routines are the text encoding expected for
+** the second parameter (the name of the function being created)
+** and the presence or absence of a destructor callback for
+** the application data pointer.
+**
+** ^The first parameter is the [database connection] to which the SQL
+** function is to be added.  ^If an application uses more than one database
+** connection then application-defined SQL functions must be added
+** to each database connection separately.
+**
+** ^The second parameter is the name of the SQL function to be created or
+** redefined.  ^The length of the name is limited to 255 bytes in a UTF-8
+** representation, exclusive of the zero-terminator.  ^Note that the name
+** length limit is in UTF-8 bytes, not characters nor UTF-16 bytes.  
+** ^Any attempt to create a function with a longer name
+** will result in [SQLITE_MISUSE] being returned.
+**
+** ^The third parameter (nArg)
+** is the number of arguments that the SQL function or
+** aggregate takes. ^If this parameter is -1, then the SQL function or
+** aggregate may take any number of arguments between 0 and the limit
+** set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]).  If the third
+** parameter is less than -1 or greater than 127 then the behavior is
+** undefined.
+**
+** ^The fourth parameter, eTextRep, specifies what
+** [SQLITE_UTF8 | text encoding] this SQL function prefers for
+** its parameters.  The application should set this parameter to
+** [SQLITE_UTF16LE] if the function implementation invokes 
+** [sqlite3_value_text16le()] on an input, or [SQLITE_UTF16BE] if the
+** implementation invokes [sqlite3_value_text16be()] on an input, or
+** [SQLITE_UTF16] if [sqlite3_value_text16()] is used, or [SQLITE_UTF8]
+** otherwise.  ^The same SQL function may be registered multiple times using
+** different preferred text encodings, with different implementations for
+** each encoding.
+** ^When multiple implementations of the same function are available, SQLite
+** will pick the one that involves the least amount of data conversion.
+**
+** ^The fourth parameter may optionally be ORed with [SQLITE_DETERMINISTIC]
+** to signal that the function will always return the same result given
+** the same inputs within a single SQL statement.  Most SQL functions are
+** deterministic.  The built-in [random()] SQL function is an example of a
+** function that is not deterministic.  The SQLite query planner is able to
+** perform additional optimizations on deterministic functions, so use
+** of the [SQLITE_DETERMINISTIC] flag is recommended where possible.
+**
+** ^(The fifth parameter is an arbitrary pointer.  The implementation of the
+** function can gain access to this pointer using [sqlite3_user_data()].)^
+**
+** ^The sixth, seventh and eighth parameters, xFunc, xStep and xFinal, are
+** pointers to C-language functions that implement the SQL function or
+** aggregate. ^A scalar SQL function requires an implementation of the xFunc
+** callback only; NULL pointers must be passed as the xStep and xFinal
+** parameters. ^An aggregate SQL function requires an implementation of xStep
+** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing
+** SQL function or aggregate, pass NULL pointers for all three function
+** callbacks.
+**
+** ^(If the ninth parameter to sqlite3_create_function_v2() is not NULL,
+** then it is destructor for the application data pointer. 
+** The destructor is invoked when the function is deleted, either by being
+** overloaded or when the database connection closes.)^
+** ^The destructor is also invoked if the call to
+** sqlite3_create_function_v2() fails.
+** ^When the destructor callback of the tenth parameter is invoked, it
+** is passed a single argument which is a copy of the application data 
+** pointer which was the fifth parameter to sqlite3_create_function_v2().
+**
+** ^It is permitted to register multiple implementations of the same
+** functions with the same name but with either differing numbers of
+** arguments or differing preferred text encodings.  ^SQLite will use
+** the implementation that most closely matches the way in which the
+** SQL function is used.  ^A function implementation with a non-negative
+** nArg parameter is a better match than a function implementation with
+** a negative nArg.  ^A function where the preferred text encoding
+** matches the database encoding is a better
+** match than a function where the encoding is different.  
+** ^A function where the encoding difference is between UTF16le and UTF16be
+** is a closer match than a function where the encoding difference is
+** between UTF8 and UTF16.
+**
+** ^Built-in functions may be overloaded by new application-defined functions.
+**
+** ^An application-defined function is permitted to call other
+** SQLite interfaces.  However, such calls must not
+** close the database connection nor finalize or reset the prepared
+** statement in which the function is running.
+*/
+SQLITE_API int sqlite3_create_function(
+  sqlite3 *db,
+  const char *zFunctionName,
+  int nArg,
+  int eTextRep,
+  void *pApp,
+  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
+  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+  void (*xFinal)(sqlite3_context*)
+);
+SQLITE_API int sqlite3_create_function16(
+  sqlite3 *db,
+  const void *zFunctionName,
+  int nArg,
+  int eTextRep,
+  void *pApp,
+  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
+  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+  void (*xFinal)(sqlite3_context*)
+);
+SQLITE_API int sqlite3_create_function_v2(
+  sqlite3 *db,
+  const char *zFunctionName,
+  int nArg,
+  int eTextRep,
+  void *pApp,
+  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
+  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+  void (*xFinal)(sqlite3_context*),
+  void(*xDestroy)(void*)
+);
+
+/*
+** CAPI3REF: Text Encodings
+**
+** These constant define integer codes that represent the various
+** text encodings supported by SQLite.
+*/
+#define SQLITE_UTF8           1    /* IMP: R-37514-35566 */
+#define SQLITE_UTF16LE        2    /* IMP: R-03371-37637 */
+#define SQLITE_UTF16BE        3    /* IMP: R-51971-34154 */
+#define SQLITE_UTF16          4    /* Use native byte order */
+#define SQLITE_ANY            5    /* Deprecated */
+#define SQLITE_UTF16_ALIGNED  8    /* sqlite3_create_collation only */
+
+/*
+** CAPI3REF: Function Flags
+**
+** These constants may be ORed together with the 
+** [SQLITE_UTF8 | preferred text encoding] as the fourth argument
+** to [sqlite3_create_function()], [sqlite3_create_function16()], or
+** [sqlite3_create_function_v2()].
+*/
+#define SQLITE_DETERMINISTIC    0x800
+
+/*
+** CAPI3REF: Deprecated Functions
+** DEPRECATED
+**
+** These functions are [deprecated].  In order to maintain
+** backwards compatibility with older code, these functions continue 
+** to be supported.  However, new applications should avoid
+** the use of these functions.  To encourage programmers to avoid
+** these functions, we will not explain what they do.
+*/
+#ifndef SQLITE_OMIT_DEPRECATED
+SQLITE_API SQLITE_DEPRECATED int sqlite3_aggregate_count(sqlite3_context*);
+SQLITE_API SQLITE_DEPRECATED int sqlite3_expired(sqlite3_stmt*);
+SQLITE_API SQLITE_DEPRECATED int sqlite3_transfer_bindings(sqlite3_stmt*, sqlite3_stmt*);
+SQLITE_API SQLITE_DEPRECATED int sqlite3_global_recover(void);
+SQLITE_API SQLITE_DEPRECATED void sqlite3_thread_cleanup(void);
+SQLITE_API SQLITE_DEPRECATED int sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),
+                      void*,sqlite3_int64);
+#endif
+
+/*
+** CAPI3REF: Obtaining SQL Values
+** METHOD: sqlite3_value
+**
+** The C-language implementation of SQL functions and aggregates uses
+** this set of interface routines to access the parameter values on
+** the function or aggregate.  
+**
+** The xFunc (for scalar functions) or xStep (for aggregates) parameters
+** to [sqlite3_create_function()] and [sqlite3_create_function16()]
+** define callbacks that implement the SQL functions and aggregates.
+** The 3rd parameter to these callbacks is an array of pointers to
+** [protected sqlite3_value] objects.  There is one [sqlite3_value] object for
+** each parameter to the SQL function.  These routines are used to
+** extract values from the [sqlite3_value] objects.
+**
+** These routines work only with [protected sqlite3_value] objects.
+** Any attempt to use these routines on an [unprotected sqlite3_value]
+** object results in undefined behavior.
+**
+** ^These routines work just like the corresponding [column access functions]
+** except that these routines take a single [protected sqlite3_value] object
+** pointer instead of a [sqlite3_stmt*] pointer and an integer column number.
+**
+** ^The sqlite3_value_text16() interface extracts a UTF-16 string
+** in the native byte-order of the host machine.  ^The
+** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces
+** extract UTF-16 strings as big-endian and little-endian respectively.
+**
+** ^(The sqlite3_value_numeric_type() interface attempts to apply
+** numeric affinity to the value.  This means that an attempt is
+** made to convert the value to an integer or floating point.  If
+** such a conversion is possible without loss of information (in other
+** words, if the value is a string that looks like a number)
+** then the conversion is performed.  Otherwise no conversion occurs.
+** The [SQLITE_INTEGER | datatype] after conversion is returned.)^
+**
+** Please pay particular attention to the fact that the pointer returned
+** from [sqlite3_value_blob()], [sqlite3_value_text()], or
+** [sqlite3_value_text16()] can be invalidated by a subsequent call to
+** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],
+** or [sqlite3_value_text16()].
+**
+** These routines must be called from the same thread as
+** the SQL function that supplied the [sqlite3_value*] parameters.
+*/
+SQLITE_API const void *sqlite3_value_blob(sqlite3_value*);
+SQLITE_API int sqlite3_value_bytes(sqlite3_value*);
+SQLITE_API int sqlite3_value_bytes16(sqlite3_value*);
+SQLITE_API double sqlite3_value_double(sqlite3_value*);
+SQLITE_API int sqlite3_value_int(sqlite3_value*);
+SQLITE_API sqlite3_int64 sqlite3_value_int64(sqlite3_value*);
+SQLITE_API const unsigned char *sqlite3_value_text(sqlite3_value*);
+SQLITE_API const void *sqlite3_value_text16(sqlite3_value*);
+SQLITE_API const void *sqlite3_value_text16le(sqlite3_value*);
+SQLITE_API const void *sqlite3_value_text16be(sqlite3_value*);
+SQLITE_API int sqlite3_value_type(sqlite3_value*);
+SQLITE_API int sqlite3_value_numeric_type(sqlite3_value*);
+
+/*
+** CAPI3REF: Finding The Subtype Of SQL Values
+** METHOD: sqlite3_value
+**
+** The sqlite3_value_subtype(V) function returns the subtype for
+** an [application-defined SQL function] argument V.  The subtype
+** information can be used to pass a limited amount of context from
+** one SQL function to another.  Use the [sqlite3_result_subtype()]
+** routine to set the subtype for the return value of an SQL function.
+**
+** SQLite makes no use of subtype itself.  It merely passes the subtype
+** from the result of one [application-defined SQL function] into the
+** input of another.
+*/
+SQLITE_API unsigned int sqlite3_value_subtype(sqlite3_value*);
+
+/*
+** CAPI3REF: Copy And Free SQL Values
+** METHOD: sqlite3_value
+**
+** ^The sqlite3_value_dup(V) interface makes a copy of the [sqlite3_value]
+** object D and returns a pointer to that copy.  ^The [sqlite3_value] returned
+** is a [protected sqlite3_value] object even if the input is not.
+** ^The sqlite3_value_dup(V) interface returns NULL if V is NULL or if a
+** memory allocation fails.
+**
+** ^The sqlite3_value_free(V) interface frees an [sqlite3_value] object
+** previously obtained from [sqlite3_value_dup()].  ^If V is a NULL pointer
+** then sqlite3_value_free(V) is a harmless no-op.
+*/
+SQLITE_API sqlite3_value *sqlite3_value_dup(const sqlite3_value*);
+SQLITE_API void sqlite3_value_free(sqlite3_value*);
+
+/*
+** CAPI3REF: Obtain Aggregate Function Context
+** METHOD: sqlite3_context
+**
+** Implementations of aggregate SQL functions use this
+** routine to allocate memory for storing their state.
+**
+** ^The first time the sqlite3_aggregate_context(C,N) routine is called 
+** for a particular aggregate function, SQLite
+** allocates N of memory, zeroes out that memory, and returns a pointer
+** to the new memory. ^On second and subsequent calls to
+** sqlite3_aggregate_context() for the same aggregate function instance,
+** the same buffer is returned.  Sqlite3_aggregate_context() is normally
+** called once for each invocation of the xStep callback and then one
+** last time when the xFinal callback is invoked.  ^(When no rows match
+** an aggregate query, the xStep() callback of the aggregate function
+** implementation is never called and xFinal() is called exactly once.
+** In those cases, sqlite3_aggregate_context() might be called for the
+** first time from within xFinal().)^
+**
+** ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer 
+** when first called if N is less than or equal to zero or if a memory
+** allocate error occurs.
+**
+** ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is
+** determined by the N parameter on first successful call.  Changing the
+** value of N in subsequent call to sqlite3_aggregate_context() within
+** the same aggregate function instance will not resize the memory
+** allocation.)^  Within the xFinal callback, it is customary to set
+** N=0 in calls to sqlite3_aggregate_context(C,N) so that no 
+** pointless memory allocations occur.
+**
+** ^SQLite automatically frees the memory allocated by 
+** sqlite3_aggregate_context() when the aggregate query concludes.
+**
+** The first parameter must be a copy of the
+** [sqlite3_context | SQL function context] that is the first parameter
+** to the xStep or xFinal callback routine that implements the aggregate
+** function.
+**
+** This routine must be called from the same thread in which
+** the aggregate SQL function is running.
+*/
+SQLITE_API void *sqlite3_aggregate_context(sqlite3_context*, int nBytes);
+
+/*
+** CAPI3REF: User Data For Functions
+** METHOD: sqlite3_context
+**
+** ^The sqlite3_user_data() interface returns a copy of
+** the pointer that was the pUserData parameter (the 5th parameter)
+** of the [sqlite3_create_function()]
+** and [sqlite3_create_function16()] routines that originally
+** registered the application defined function.
+**
+** This routine must be called from the same thread in which
+** the application-defined function is running.
+*/
+SQLITE_API void *sqlite3_user_data(sqlite3_context*);
+
+/*
+** CAPI3REF: Database Connection For Functions
+** METHOD: sqlite3_context
+**
+** ^The sqlite3_context_db_handle() interface returns a copy of
+** the pointer to the [database connection] (the 1st parameter)
+** of the [sqlite3_create_function()]
+** and [sqlite3_create_function16()] routines that originally
+** registered the application defined function.
+*/
+SQLITE_API sqlite3 *sqlite3_context_db_handle(sqlite3_context*);
+
+/*
+** CAPI3REF: Function Auxiliary Data
+** METHOD: sqlite3_context
+**
+** These functions may be used by (non-aggregate) SQL functions to
+** associate metadata with argument values. If the same value is passed to
+** multiple invocations of the same SQL function during query execution, under
+** some circumstances the associated metadata may be preserved.  An example
+** of where this might be useful is in a regular-expression matching
+** function. The compiled version of the regular expression can be stored as
+** metadata associated with the pattern string.  
+** Then as long as the pattern string remains the same,
+** the compiled regular expression can be reused on multiple
+** invocations of the same function.
+**
+** ^The sqlite3_get_auxdata() interface returns a pointer to the metadata
+** associated by the sqlite3_set_auxdata() function with the Nth argument
+** value to the application-defined function. ^If there is no metadata
+** associated with the function argument, this sqlite3_get_auxdata() interface
+** returns a NULL pointer.
+**
+** ^The sqlite3_set_auxdata(C,N,P,X) interface saves P as metadata for the N-th
+** argument of the application-defined function.  ^Subsequent
+** calls to sqlite3_get_auxdata(C,N) return P from the most recent
+** sqlite3_set_auxdata(C,N,P,X) call if the metadata is still valid or
+** NULL if the metadata has been discarded.
+** ^After each call to sqlite3_set_auxdata(C,N,P,X) where X is not NULL,
+** SQLite will invoke the destructor function X with parameter P exactly
+** once, when the metadata is discarded.
+** SQLite is free to discard the metadata at any time, including: <ul>
+** <li> ^(when the corresponding function parameter changes)^, or
+** <li> ^(when [sqlite3_reset()] or [sqlite3_finalize()] is called for the
+**      SQL statement)^, or
+** <li> ^(when sqlite3_set_auxdata() is invoked again on the same
+**       parameter)^, or
+** <li> ^(during the original sqlite3_set_auxdata() call when a memory 
+**      allocation error occurs.)^ </ul>
+**
+** Note the last bullet in particular.  The destructor X in 
+** sqlite3_set_auxdata(C,N,P,X) might be called immediately, before the
+** sqlite3_set_auxdata() interface even returns.  Hence sqlite3_set_auxdata()
+** should be called near the end of the function implementation and the
+** function implementation should not make any use of P after
+** sqlite3_set_auxdata() has been called.
+**
+** ^(In practice, metadata is preserved between function calls for
+** function parameters that are compile-time constants, including literal
+** values and [parameters] and expressions composed from the same.)^
+**
+** These routines must be called from the same thread in which
+** the SQL function is running.
+*/
+SQLITE_API void *sqlite3_get_auxdata(sqlite3_context*, int N);
+SQLITE_API void sqlite3_set_auxdata(sqlite3_context*, int N, void*, void (*)(void*));
+
+
+/*
+** CAPI3REF: Constants Defining Special Destructor Behavior
+**
+** These are special values for the destructor that is passed in as the
+** final argument to routines like [sqlite3_result_blob()].  ^If the destructor
+** argument is SQLITE_STATIC, it means that the content pointer is constant
+** and will never change.  It does not need to be destroyed.  ^The
+** SQLITE_TRANSIENT value means that the content will likely change in
+** the near future and that SQLite should make its own private copy of
+** the content before returning.
+**
+** The typedef is necessary to work around problems in certain
+** C++ compilers.
+*/
+typedef void (*sqlite3_destructor_type)(void*);
+#define SQLITE_STATIC      ((sqlite3_destructor_type)0)
+#define SQLITE_TRANSIENT   ((sqlite3_destructor_type)-1)
+
+/*
+** CAPI3REF: Setting The Result Of An SQL Function
+** METHOD: sqlite3_context
+**
+** These routines are used by the xFunc or xFinal callbacks that
+** implement SQL functions and aggregates.  See
+** [sqlite3_create_function()] and [sqlite3_create_function16()]
+** for additional information.
+**
+** These functions work very much like the [parameter binding] family of
+** functions used to bind values to host parameters in prepared statements.
+** Refer to the [SQL parameter] documentation for additional information.
+**
+** ^The sqlite3_result_blob() interface sets the result from
+** an application-defined function to be the BLOB whose content is pointed
+** to by the second parameter and which is N bytes long where N is the
+** third parameter.
+**
+** ^The sqlite3_result_zeroblob(C,N) and sqlite3_result_zeroblob64(C,N)
+** interfaces set the result of the application-defined function to be
+** a BLOB containing all zero bytes and N bytes in size.
+**
+** ^The sqlite3_result_double() interface sets the result from
+** an application-defined function to be a floating point value specified
+** by its 2nd argument.
+**
+** ^The sqlite3_result_error() and sqlite3_result_error16() functions
+** cause the implemented SQL function to throw an exception.
+** ^SQLite uses the string pointed to by the
+** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()
+** as the text of an error message.  ^SQLite interprets the error
+** message string from sqlite3_result_error() as UTF-8. ^SQLite
+** interprets the string from sqlite3_result_error16() as UTF-16 in native
+** byte order.  ^If the third parameter to sqlite3_result_error()
+** or sqlite3_result_error16() is negative then SQLite takes as the error
+** message all text up through the first zero character.
+** ^If the third parameter to sqlite3_result_error() or
+** sqlite3_result_error16() is non-negative then SQLite takes that many
+** bytes (not characters) from the 2nd parameter as the error message.
+** ^The sqlite3_result_error() and sqlite3_result_error16()
+** routines make a private copy of the error message text before
+** they return.  Hence, the calling function can deallocate or
+** modify the text after they return without harm.
+** ^The sqlite3_result_error_code() function changes the error code
+** returned by SQLite as a result of an error in a function.  ^By default,
+** the error code is SQLITE_ERROR.  ^A subsequent call to sqlite3_result_error()
+** or sqlite3_result_error16() resets the error code to SQLITE_ERROR.
+**
+** ^The sqlite3_result_error_toobig() interface causes SQLite to throw an
+** error indicating that a string or BLOB is too long to represent.
+**
+** ^The sqlite3_result_error_nomem() interface causes SQLite to throw an
+** error indicating that a memory allocation failed.
+**
+** ^The sqlite3_result_int() interface sets the return value
+** of the application-defined function to be the 32-bit signed integer
+** value given in the 2nd argument.
+** ^The sqlite3_result_int64() interface sets the return value
+** of the application-defined function to be the 64-bit signed integer
+** value given in the 2nd argument.
+**
+** ^The sqlite3_result_null() interface sets the return value
+** of the application-defined function to be NULL.
+**
+** ^The sqlite3_result_text(), sqlite3_result_text16(),
+** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces
+** set the return value of the application-defined function to be
+** a text string which is represented as UTF-8, UTF-16 native byte order,
+** UTF-16 little endian, or UTF-16 big endian, respectively.
+** ^The sqlite3_result_text64() interface sets the return value of an
+** application-defined function to be a text string in an encoding
+** specified by the fifth (and last) parameter, which must be one
+** of [SQLITE_UTF8], [SQLITE_UTF16], [SQLITE_UTF16BE], or [SQLITE_UTF16LE].
+** ^SQLite takes the text result from the application from
+** the 2nd parameter of the sqlite3_result_text* interfaces.
+** ^If the 3rd parameter to the sqlite3_result_text* interfaces
+** is negative, then SQLite takes result text from the 2nd parameter
+** through the first zero character.
+** ^If the 3rd parameter to the sqlite3_result_text* interfaces
+** is non-negative, then as many bytes (not characters) of the text
+** pointed to by the 2nd parameter are taken as the application-defined
+** function result.  If the 3rd parameter is non-negative, then it
+** must be the byte offset into the string where the NUL terminator would
+** appear if the string where NUL terminated.  If any NUL characters occur
+** in the string at a byte offset that is less than the value of the 3rd
+** parameter, then the resulting string will contain embedded NULs and the
+** result of expressions operating on strings with embedded NULs is undefined.
+** ^If the 4th parameter to the sqlite3_result_text* interfaces
+** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
+** function as the destructor on the text or BLOB result when it has
+** finished using that result.
+** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
+** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
+** assumes that the text or BLOB result is in constant space and does not
+** copy the content of the parameter nor call a destructor on the content
+** when it has finished using that result.
+** ^If the 4th parameter to the sqlite3_result_text* interfaces
+** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT
+** then SQLite makes a copy of the result into space obtained from
+** from [sqlite3_malloc()] before it returns.
+**
+** ^The sqlite3_result_value() interface sets the result of
+** the application-defined function to be a copy of the
+** [unprotected sqlite3_value] object specified by the 2nd parameter.  ^The
+** sqlite3_result_value() interface makes a copy of the [sqlite3_value]
+** so that the [sqlite3_value] specified in the parameter may change or
+** be deallocated after sqlite3_result_value() returns without harm.
+** ^A [protected sqlite3_value] object may always be used where an
+** [unprotected sqlite3_value] object is required, so either
+** kind of [sqlite3_value] object can be used with this interface.
+**
+** If these routines are called from within the different thread
+** than the one containing the application-defined function that received
+** the [sqlite3_context] pointer, the results are undefined.
+*/
+SQLITE_API void sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*));
+SQLITE_API void sqlite3_result_blob64(sqlite3_context*,const void*,
+                           sqlite3_uint64,void(*)(void*));
+SQLITE_API void sqlite3_result_double(sqlite3_context*, double);
+SQLITE_API void sqlite3_result_error(sqlite3_context*, const char*, int);
+SQLITE_API void sqlite3_result_error16(sqlite3_context*, const void*, int);
+SQLITE_API void sqlite3_result_error_toobig(sqlite3_context*);
+SQLITE_API void sqlite3_result_error_nomem(sqlite3_context*);
+SQLITE_API void sqlite3_result_error_code(sqlite3_context*, int);
+SQLITE_API void sqlite3_result_int(sqlite3_context*, int);
+SQLITE_API void sqlite3_result_int64(sqlite3_context*, sqlite3_int64);
+SQLITE_API void sqlite3_result_null(sqlite3_context*);
+SQLITE_API void sqlite3_result_text(sqlite3_context*, const char*, int, void(*)(void*));
+SQLITE_API void sqlite3_result_text64(sqlite3_context*, const char*,sqlite3_uint64,
+                           void(*)(void*), unsigned char encoding);
+SQLITE_API void sqlite3_result_text16(sqlite3_context*, const void*, int, void(*)(void*));
+SQLITE_API void sqlite3_result_text16le(sqlite3_context*, const void*, int,void(*)(void*));
+SQLITE_API void sqlite3_result_text16be(sqlite3_context*, const void*, int,void(*)(void*));
+SQLITE_API void sqlite3_result_value(sqlite3_context*, sqlite3_value*);
+SQLITE_API void sqlite3_result_zeroblob(sqlite3_context*, int n);
+SQLITE_API int sqlite3_result_zeroblob64(sqlite3_context*, sqlite3_uint64 n);
+
+
+/*
+** CAPI3REF: Setting The Subtype Of An SQL Function
+** METHOD: sqlite3_context
+**
+** The sqlite3_result_subtype(C,T) function causes the subtype of
+** the result from the [application-defined SQL function] with 
+** [sqlite3_context] C to be the value T.  Only the lower 8 bits 
+** of the subtype T are preserved in current versions of SQLite;
+** higher order bits are discarded.
+** The number of subtype bytes preserved by SQLite might increase
+** in future releases of SQLite.
+*/
+SQLITE_API void sqlite3_result_subtype(sqlite3_context*,unsigned int);
+
+/*
+** CAPI3REF: Define New Collating Sequences
+** METHOD: sqlite3
+**
+** ^These functions add, remove, or modify a [collation] associated
+** with the [database connection] specified as the first argument.
+**
+** ^The name of the collation is a UTF-8 string
+** for sqlite3_create_collation() and sqlite3_create_collation_v2()
+** and a UTF-16 string in native byte order for sqlite3_create_collation16().
+** ^Collation names that compare equal according to [sqlite3_strnicmp()] are
+** considered to be the same name.
+**
+** ^(The third argument (eTextRep) must be one of the constants:
+** <ul>
+** <li> [SQLITE_UTF8],
+** <li> [SQLITE_UTF16LE],
+** <li> [SQLITE_UTF16BE],
+** <li> [SQLITE_UTF16], or
+** <li> [SQLITE_UTF16_ALIGNED].
+** </ul>)^
+** ^The eTextRep argument determines the encoding of strings passed
+** to the collating function callback, xCallback.
+** ^The [SQLITE_UTF16] and [SQLITE_UTF16_ALIGNED] values for eTextRep
+** force strings to be UTF16 with native byte order.
+** ^The [SQLITE_UTF16_ALIGNED] value for eTextRep forces strings to begin
+** on an even byte address.
+**
+** ^The fourth argument, pArg, is an application data pointer that is passed
+** through as the first argument to the collating function callback.
+**
+** ^The fifth argument, xCallback, is a pointer to the collating function.
+** ^Multiple collating functions can be registered using the same name but
+** with different eTextRep parameters and SQLite will use whichever
+** function requires the least amount of data transformation.
+** ^If the xCallback argument is NULL then the collating function is
+** deleted.  ^When all collating functions having the same name are deleted,
+** that collation is no longer usable.
+**
+** ^The collating function callback is invoked with a copy of the pArg 
+** application data pointer and with two strings in the encoding specified
+** by the eTextRep argument.  The collating function must return an
+** integer that is negative, zero, or positive
+** if the first string is less than, equal to, or greater than the second,
+** respectively.  A collating function must always return the same answer
+** given the same inputs.  If two or more collating functions are registered
+** to the same collation name (using different eTextRep values) then all
+** must give an equivalent answer when invoked with equivalent strings.
+** The collating function must obey the following properties for all
+** strings A, B, and C:
+**
+** <ol>
+** <li> If A==B then B==A.
+** <li> If A==B and B==C then A==C.
+** <li> If A&lt;B THEN B&gt;A.
+** <li> If A&lt;B and B&lt;C then A&lt;C.
+** </ol>
+**
+** If a collating function fails any of the above constraints and that
+** collating function is  registered and used, then the behavior of SQLite
+** is undefined.
+**
+** ^The sqlite3_create_collation_v2() works like sqlite3_create_collation()
+** with the addition that the xDestroy callback is invoked on pArg when
+** the collating function is deleted.
+** ^Collating functions are deleted when they are overridden by later
+** calls to the collation creation functions or when the
+** [database connection] is closed using [sqlite3_close()].
+**
+** ^The xDestroy callback is <u>not</u> called if the 
+** sqlite3_create_collation_v2() function fails.  Applications that invoke
+** sqlite3_create_collation_v2() with a non-NULL xDestroy argument should 
+** check the return code and dispose of the application data pointer
+** themselves rather than expecting SQLite to deal with it for them.
+** This is different from every other SQLite interface.  The inconsistency 
+** is unfortunate but cannot be changed without breaking backwards 
+** compatibility.
+**
+** See also:  [sqlite3_collation_needed()] and [sqlite3_collation_needed16()].
+*/
+SQLITE_API int sqlite3_create_collation(
+  sqlite3*, 
+  const char *zName, 
+  int eTextRep, 
+  void *pArg,
+  int(*xCompare)(void*,int,const void*,int,const void*)
+);
+SQLITE_API int sqlite3_create_collation_v2(
+  sqlite3*, 
+  const char *zName, 
+  int eTextRep, 
+  void *pArg,
+  int(*xCompare)(void*,int,const void*,int,const void*),
+  void(*xDestroy)(void*)
+);
+SQLITE_API int sqlite3_create_collation16(
+  sqlite3*, 
+  const void *zName,
+  int eTextRep, 
+  void *pArg,
+  int(*xCompare)(void*,int,const void*,int,const void*)
+);
+
+/*
+** CAPI3REF: Collation Needed Callbacks
+** METHOD: sqlite3
+**
+** ^To avoid having to register all collation sequences before a database
+** can be used, a single callback function may be registered with the
+** [database connection] to be invoked whenever an undefined collation
+** sequence is required.
+**
+** ^If the function is registered using the sqlite3_collation_needed() API,
+** then it is passed the names of undefined collation sequences as strings
+** encoded in UTF-8. ^If sqlite3_collation_needed16() is used,
+** the names are passed as UTF-16 in machine native byte order.
+** ^A call to either function replaces the existing collation-needed callback.
+**
+** ^(When the callback is invoked, the first argument passed is a copy
+** of the second argument to sqlite3_collation_needed() or
+** sqlite3_collation_needed16().  The second argument is the database
+** connection.  The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE],
+** or [SQLITE_UTF16LE], indicating the most desirable form of the collation
+** sequence function required.  The fourth parameter is the name of the
+** required collation sequence.)^
+**
+** The callback function should register the desired collation using
+** [sqlite3_create_collation()], [sqlite3_create_collation16()], or
+** [sqlite3_create_collation_v2()].
+*/
+SQLITE_API int sqlite3_collation_needed(
+  sqlite3*, 
+  void*, 
+  void(*)(void*,sqlite3*,int eTextRep,const char*)
+);
+SQLITE_API int sqlite3_collation_needed16(
+  sqlite3*, 
+  void*,
+  void(*)(void*,sqlite3*,int eTextRep,const void*)
+);
+
+#ifdef SQLITE_HAS_CODEC
+/*
+** Specify the key for an encrypted database.  This routine should be
+** called right after sqlite3_open().
+**
+** The code to implement this API is not available in the public release
+** of SQLite.
+*/
+SQLITE_API int sqlite3_key(
+  sqlite3 *db,                   /* Database to be rekeyed */
+  const void *pKey, int nKey     /* The key */
+);
+SQLITE_API int sqlite3_key_v2(
+  sqlite3 *db,                   /* Database to be rekeyed */
+  const char *zDbName,           /* Name of the database */
+  const void *pKey, int nKey     /* The key */
+);
+
+/*
+** Change the key on an open database.  If the current database is not
+** encrypted, this routine will encrypt it.  If pNew==0 or nNew==0, the
+** database is decrypted.
+**
+** The code to implement this API is not available in the public release
+** of SQLite.
+*/
+SQLITE_API int sqlite3_rekey(
+  sqlite3 *db,                   /* Database to be rekeyed */
+  const void *pKey, int nKey     /* The new key */
+);
+SQLITE_API int sqlite3_rekey_v2(
+  sqlite3 *db,                   /* Database to be rekeyed */
+  const char *zDbName,           /* Name of the database */
+  const void *pKey, int nKey     /* The new key */
+);
+
+/*
+** Specify the activation key for a SEE database.  Unless 
+** activated, none of the SEE routines will work.
+*/
+SQLITE_API void sqlite3_activate_see(
+  const char *zPassPhrase        /* Activation phrase */
+);
+#endif
+
+#ifdef SQLITE_ENABLE_CEROD
+/*
+** Specify the activation key for a CEROD database.  Unless 
+** activated, none of the CEROD routines will work.
+*/
+SQLITE_API void sqlite3_activate_cerod(
+  const char *zPassPhrase        /* Activation phrase */
+);
+#endif
+
+/*
+** CAPI3REF: Suspend Execution For A Short Time
+**
+** The sqlite3_sleep() function causes the current thread to suspend execution
+** for at least a number of milliseconds specified in its parameter.
+**
+** If the operating system does not support sleep requests with
+** millisecond time resolution, then the time will be rounded up to
+** the nearest second. The number of milliseconds of sleep actually
+** requested from the operating system is returned.
+**
+** ^SQLite implements this interface by calling the xSleep()
+** method of the default [sqlite3_vfs] object.  If the xSleep() method
+** of the default VFS is not implemented correctly, or not implemented at
+** all, then the behavior of sqlite3_sleep() may deviate from the description
+** in the previous paragraphs.
+*/
+SQLITE_API int sqlite3_sleep(int);
+
+/*
+** CAPI3REF: Name Of The Folder Holding Temporary Files
+**
+** ^(If this global variable is made to point to a string which is
+** the name of a folder (a.k.a. directory), then all temporary files
+** created by SQLite when using a built-in [sqlite3_vfs | VFS]
+** will be placed in that directory.)^  ^If this variable
+** is a NULL pointer, then SQLite performs a search for an appropriate
+** temporary file directory.
+**
+** Applications are strongly discouraged from using this global variable.
+** It is required to set a temporary folder on Windows Runtime (WinRT).
+** But for all other platforms, it is highly recommended that applications
+** neither read nor write this variable.  This global variable is a relic
+** that exists for backwards compatibility of legacy applications and should
+** be avoided in new projects.
+**
+** It is not safe to read or modify this variable in more than one
+** thread at a time.  It is not safe to read or modify this variable
+** if a [database connection] is being used at the same time in a separate
+** thread.
+** It is intended that this variable be set once
+** as part of process initialization and before any SQLite interface
+** routines have been called and that this variable remain unchanged
+** thereafter.
+**
+** ^The [temp_store_directory pragma] may modify this variable and cause
+** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
+** the [temp_store_directory pragma] always assumes that any string
+** that this variable points to is held in memory obtained from 
+** [sqlite3_malloc] and the pragma may attempt to free that memory
+** using [sqlite3_free].
+** Hence, if this variable is modified directly, either it should be
+** made NULL or made to point to memory obtained from [sqlite3_malloc]
+** or else the use of the [temp_store_directory pragma] should be avoided.
+** Except when requested by the [temp_store_directory pragma], SQLite
+** does not free the memory that sqlite3_temp_directory points to.  If
+** the application wants that memory to be freed, it must do
+** so itself, taking care to only do so after all [database connection]
+** objects have been destroyed.
+**
+** <b>Note to Windows Runtime users:</b>  The temporary directory must be set
+** prior to calling [sqlite3_open] or [sqlite3_open_v2].  Otherwise, various
+** features that require the use of temporary files may fail.  Here is an
+** example of how to do this using C++ with the Windows Runtime:
+**
+** <blockquote><pre>
+** LPCWSTR zPath = Windows::Storage::ApplicationData::Current->
+** &nbsp;     TemporaryFolder->Path->Data();
+** char zPathBuf&#91;MAX_PATH + 1&#93;;
+** memset(zPathBuf, 0, sizeof(zPathBuf));
+** WideCharToMultiByte(CP_UTF8, 0, zPath, -1, zPathBuf, sizeof(zPathBuf),
+** &nbsp;     NULL, NULL);
+** sqlite3_temp_directory = sqlite3_mprintf("%s", zPathBuf);
+** </pre></blockquote>
+*/
+SQLITE_API char *sqlite3_temp_directory;
+
+/*
+** CAPI3REF: Name Of The Folder Holding Database Files
+**
+** ^(If this global variable is made to point to a string which is
+** the name of a folder (a.k.a. directory), then all database files
+** specified with a relative pathname and created or accessed by
+** SQLite when using a built-in windows [sqlite3_vfs | VFS] will be assumed
+** to be relative to that directory.)^ ^If this variable is a NULL
+** pointer, then SQLite assumes that all database files specified
+** with a relative pathname are relative to the current directory
+** for the process.  Only the windows VFS makes use of this global
+** variable; it is ignored by the unix VFS.
+**
+** Changing the value of this variable while a database connection is
+** open can result in a corrupt database.
+**
+** It is not safe to read or modify this variable in more than one
+** thread at a time.  It is not safe to read or modify this variable
+** if a [database connection] is being used at the same time in a separate
+** thread.
+** It is intended that this variable be set once
+** as part of process initialization and before any SQLite interface
+** routines have been called and that this variable remain unchanged
+** thereafter.
+**
+** ^The [data_store_directory pragma] may modify this variable and cause
+** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
+** the [data_store_directory pragma] always assumes that any string
+** that this variable points to is held in memory obtained from 
+** [sqlite3_malloc] and the pragma may attempt to free that memory
+** using [sqlite3_free].
+** Hence, if this variable is modified directly, either it should be
+** made NULL or made to point to memory obtained from [sqlite3_malloc]
+** or else the use of the [data_store_directory pragma] should be avoided.
+*/
+SQLITE_API char *sqlite3_data_directory;
+
+/*
+** CAPI3REF: Test For Auto-Commit Mode
+** KEYWORDS: {autocommit mode}
+** METHOD: sqlite3
+**
+** ^The sqlite3_get_autocommit() interface returns non-zero or
+** zero if the given database connection is or is not in autocommit mode,
+** respectively.  ^Autocommit mode is on by default.
+** ^Autocommit mode is disabled by a [BEGIN] statement.
+** ^Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK].
+**
+** If certain kinds of errors occur on a statement within a multi-statement
+** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR],
+** [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the
+** transaction might be rolled back automatically.  The only way to
+** find out whether SQLite automatically rolled back the transaction after
+** an error is to use this function.
+**
+** If another thread changes the autocommit status of the database
+** connection while this routine is running, then the return value
+** is undefined.
+*/
+SQLITE_API int sqlite3_get_autocommit(sqlite3*);
+
+/*
+** CAPI3REF: Find The Database Handle Of A Prepared Statement
+** METHOD: sqlite3_stmt
+**
+** ^The sqlite3_db_handle interface returns the [database connection] handle
+** to which a [prepared statement] belongs.  ^The [database connection]
+** returned by sqlite3_db_handle is the same [database connection]
+** that was the first argument
+** to the [sqlite3_prepare_v2()] call (or its variants) that was used to
+** create the statement in the first place.
+*/
+SQLITE_API sqlite3 *sqlite3_db_handle(sqlite3_stmt*);
+
+/*
+** CAPI3REF: Return The Filename For A Database Connection
+** METHOD: sqlite3
+**
+** ^The sqlite3_db_filename(D,N) interface returns a pointer to a filename
+** associated with database N of connection D.  ^The main database file
+** has the name "main".  If there is no attached database N on the database
+** connection D, or if database N is a temporary or in-memory database, then
+** a NULL pointer is returned.
+**
+** ^The filename returned by this function is the output of the
+** xFullPathname method of the [VFS].  ^In other words, the filename
+** will be an absolute pathname, even if the filename used
+** to open the database originally was a URI or relative pathname.
+*/
+SQLITE_API const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName);
+
+/*
+** CAPI3REF: Determine if a database is read-only
+** METHOD: sqlite3
+**
+** ^The sqlite3_db_readonly(D,N) interface returns 1 if the database N
+** of connection D is read-only, 0 if it is read/write, or -1 if N is not
+** the name of a database on connection D.
+*/
+SQLITE_API int sqlite3_db_readonly(sqlite3 *db, const char *zDbName);
+
+/*
+** CAPI3REF: Find the next prepared statement
+** METHOD: sqlite3
+**
+** ^This interface returns a pointer to the next [prepared statement] after
+** pStmt associated with the [database connection] pDb.  ^If pStmt is NULL
+** then this interface returns a pointer to the first prepared statement
+** associated with the database connection pDb.  ^If no prepared statement
+** satisfies the conditions of this routine, it returns NULL.
+**
+** The [database connection] pointer D in a call to
+** [sqlite3_next_stmt(D,S)] must refer to an open database
+** connection and in particular must not be a NULL pointer.
+*/
+SQLITE_API sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Commit And Rollback Notification Callbacks
+** METHOD: sqlite3
+**
+** ^The sqlite3_commit_hook() interface registers a callback
+** function to be invoked whenever a transaction is [COMMIT | committed].
+** ^Any callback set by a previous call to sqlite3_commit_hook()
+** for the same database connection is overridden.
+** ^The sqlite3_rollback_hook() interface registers a callback
+** function to be invoked whenever a transaction is [ROLLBACK | rolled back].
+** ^Any callback set by a previous call to sqlite3_rollback_hook()
+** for the same database connection is overridden.
+** ^The pArg argument is passed through to the callback.
+** ^If the callback on a commit hook function returns non-zero,
+** then the commit is converted into a rollback.
+**
+** ^The sqlite3_commit_hook(D,C,P) and sqlite3_rollback_hook(D,C,P) functions
+** return the P argument from the previous call of the same function
+** on the same [database connection] D, or NULL for
+** the first call for each function on D.
+**
+** The commit and rollback hook callbacks are not reentrant.
+** The callback implementation must not do anything that will modify
+** the database connection that invoked the callback.  Any actions
+** to modify the database connection must be deferred until after the
+** completion of the [sqlite3_step()] call that triggered the commit
+** or rollback hook in the first place.
+** Note that running any other SQL statements, including SELECT statements,
+** or merely calling [sqlite3_prepare_v2()] and [sqlite3_step()] will modify
+** the database connections for the meaning of "modify" in this paragraph.
+**
+** ^Registering a NULL function disables the callback.
+**
+** ^When the commit hook callback routine returns zero, the [COMMIT]
+** operation is allowed to continue normally.  ^If the commit hook
+** returns non-zero, then the [COMMIT] is converted into a [ROLLBACK].
+** ^The rollback hook is invoked on a rollback that results from a commit
+** hook returning non-zero, just as it would be with any other rollback.
+**
+** ^For the purposes of this API, a transaction is said to have been
+** rolled back if an explicit "ROLLBACK" statement is executed, or
+** an error or constraint causes an implicit rollback to occur.
+** ^The rollback callback is not invoked if a transaction is
+** automatically rolled back because the database connection is closed.
+**
+** See also the [sqlite3_update_hook()] interface.
+*/
+SQLITE_API void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
+SQLITE_API void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
+
+/*
+** CAPI3REF: Data Change Notification Callbacks
+** METHOD: sqlite3
+**
+** ^The sqlite3_update_hook() interface registers a callback function
+** with the [database connection] identified by the first argument
+** to be invoked whenever a row is updated, inserted or deleted in
+** a [rowid table].
+** ^Any callback set by a previous call to this function
+** for the same database connection is overridden.
+**
+** ^The second argument is a pointer to the function to invoke when a
+** row is updated, inserted or deleted in a rowid table.
+** ^The first argument to the callback is a copy of the third argument
+** to sqlite3_update_hook().
+** ^The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE],
+** or [SQLITE_UPDATE], depending on the operation that caused the callback
+** to be invoked.
+** ^The third and fourth arguments to the callback contain pointers to the
+** database and table name containing the affected row.
+** ^The final callback parameter is the [rowid] of the row.
+** ^In the case of an update, this is the [rowid] after the update takes place.
+**
+** ^(The update hook is not invoked when internal system tables are
+** modified (i.e. sqlite_master and sqlite_sequence).)^
+** ^The update hook is not invoked when [WITHOUT ROWID] tables are modified.
+**
+** ^In the current implementation, the update hook
+** is not invoked when duplication rows are deleted because of an
+** [ON CONFLICT | ON CONFLICT REPLACE] clause.  ^Nor is the update hook
+** invoked when rows are deleted using the [truncate optimization].
+** The exceptions defined in this paragraph might change in a future
+** release of SQLite.
+**
+** The update hook implementation must not do anything that will modify
+** the database connection that invoked the update hook.  Any actions
+** to modify the database connection must be deferred until after the
+** completion of the [sqlite3_step()] call that triggered the update hook.
+** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
+** database connections for the meaning of "modify" in this paragraph.
+**
+** ^The sqlite3_update_hook(D,C,P) function
+** returns the P argument from the previous call
+** on the same [database connection] D, or NULL for
+** the first call on D.
+**
+** See also the [sqlite3_commit_hook()], [sqlite3_rollback_hook()],
+** and [sqlite3_preupdate_hook()] interfaces.
+*/
+SQLITE_API void *sqlite3_update_hook(
+  sqlite3*, 
+  void(*)(void *,int ,char const *,char const *,sqlite3_int64),
+  void*
+);
+
+/*
+** CAPI3REF: Enable Or Disable Shared Pager Cache
+**
+** ^(This routine enables or disables the sharing of the database cache
+** and schema data structures between [database connection | connections]
+** to the same database. Sharing is enabled if the argument is true
+** and disabled if the argument is false.)^
+**
+** ^Cache sharing is enabled and disabled for an entire process.
+** This is a change as of SQLite [version 3.5.0] ([dateof:3.5.0]). 
+** In prior versions of SQLite,
+** sharing was enabled or disabled for each thread separately.
+**
+** ^(The cache sharing mode set by this interface effects all subsequent
+** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()].
+** Existing database connections continue use the sharing mode
+** that was in effect at the time they were opened.)^
+**
+** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled
+** successfully.  An [error code] is returned otherwise.)^
+**
+** ^Shared cache is disabled by default. But this might change in
+** future releases of SQLite.  Applications that care about shared
+** cache setting should set it explicitly.
+**
+** Note: This method is disabled on MacOS X 10.7 and iOS version 5.0
+** and will always return SQLITE_MISUSE. On those systems, 
+** shared cache mode should be enabled per-database connection via 
+** [sqlite3_open_v2()] with [SQLITE_OPEN_SHAREDCACHE].
+**
+** This interface is threadsafe on processors where writing a
+** 32-bit integer is atomic.
+**
+** See Also:  [SQLite Shared-Cache Mode]
+*/
+SQLITE_API int sqlite3_enable_shared_cache(int);
+
+/*
+** CAPI3REF: Attempt To Free Heap Memory
+**
+** ^The sqlite3_release_memory() interface attempts to free N bytes
+** of heap memory by deallocating non-essential memory allocations
+** held by the database library.   Memory used to cache database
+** pages to improve performance is an example of non-essential memory.
+** ^sqlite3_release_memory() returns the number of bytes actually freed,
+** which might be more or less than the amount requested.
+** ^The sqlite3_release_memory() routine is a no-op returning zero
+** if SQLite is not compiled with [SQLITE_ENABLE_MEMORY_MANAGEMENT].
+**
+** See also: [sqlite3_db_release_memory()]
+*/
+SQLITE_API int sqlite3_release_memory(int);
+
+/*
+** CAPI3REF: Free Memory Used By A Database Connection
+** METHOD: sqlite3
+**
+** ^The sqlite3_db_release_memory(D) interface attempts to free as much heap
+** memory as possible from database connection D. Unlike the
+** [sqlite3_release_memory()] interface, this interface is in effect even
+** when the [SQLITE_ENABLE_MEMORY_MANAGEMENT] compile-time option is
+** omitted.
+**
+** See also: [sqlite3_release_memory()]
+*/
+SQLITE_API int sqlite3_db_release_memory(sqlite3*);
+
+/*
+** CAPI3REF: Impose A Limit On Heap Size
+**
+** ^The sqlite3_soft_heap_limit64() interface sets and/or queries the
+** soft limit on the amount of heap memory that may be allocated by SQLite.
+** ^SQLite strives to keep heap memory utilization below the soft heap
+** limit by reducing the number of pages held in the page cache
+** as heap memory usages approaches the limit.
+** ^The soft heap limit is "soft" because even though SQLite strives to stay
+** below the limit, it will exceed the limit rather than generate
+** an [SQLITE_NOMEM] error.  In other words, the soft heap limit 
+** is advisory only.
+**
+** ^The return value from sqlite3_soft_heap_limit64() is the size of
+** the soft heap limit prior to the call, or negative in the case of an
+** error.  ^If the argument N is negative
+** then no change is made to the soft heap limit.  Hence, the current
+** size of the soft heap limit can be determined by invoking
+** sqlite3_soft_heap_limit64() with a negative argument.
+**
+** ^If the argument N is zero then the soft heap limit is disabled.
+**
+** ^(The soft heap limit is not enforced in the current implementation
+** if one or more of following conditions are true:
+**
+** <ul>
+** <li> The soft heap limit is set to zero.
+** <li> Memory accounting is disabled using a combination of the
+**      [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and
+**      the [SQLITE_DEFAULT_MEMSTATUS] compile-time option.
+** <li> An alternative page cache implementation is specified using
+**      [sqlite3_config]([SQLITE_CONFIG_PCACHE2],...).
+** <li> The page cache allocates from its own memory pool supplied
+**      by [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],...) rather than
+**      from the heap.
+** </ul>)^
+**
+** Beginning with SQLite [version 3.7.3] ([dateof:3.7.3]), 
+** the soft heap limit is enforced
+** regardless of whether or not the [SQLITE_ENABLE_MEMORY_MANAGEMENT]
+** compile-time option is invoked.  With [SQLITE_ENABLE_MEMORY_MANAGEMENT],
+** the soft heap limit is enforced on every memory allocation.  Without
+** [SQLITE_ENABLE_MEMORY_MANAGEMENT], the soft heap limit is only enforced
+** when memory is allocated by the page cache.  Testing suggests that because
+** the page cache is the predominate memory user in SQLite, most
+** applications will achieve adequate soft heap limit enforcement without
+** the use of [SQLITE_ENABLE_MEMORY_MANAGEMENT].
+**
+** The circumstances under which SQLite will enforce the soft heap limit may
+** changes in future releases of SQLite.
+*/
+SQLITE_API sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 N);
+
+/*
+** CAPI3REF: Deprecated Soft Heap Limit Interface
+** DEPRECATED
+**
+** This is a deprecated version of the [sqlite3_soft_heap_limit64()]
+** interface.  This routine is provided for historical compatibility
+** only.  All new applications should use the
+** [sqlite3_soft_heap_limit64()] interface rather than this one.
+*/
+SQLITE_API SQLITE_DEPRECATED void sqlite3_soft_heap_limit(int N);
+
+
+/*
+** CAPI3REF: Extract Metadata About A Column Of A Table
+** METHOD: sqlite3
+**
+** ^(The sqlite3_table_column_metadata(X,D,T,C,....) routine returns
+** information about column C of table T in database D
+** on [database connection] X.)^  ^The sqlite3_table_column_metadata()
+** interface returns SQLITE_OK and fills in the non-NULL pointers in
+** the final five arguments with appropriate values if the specified
+** column exists.  ^The sqlite3_table_column_metadata() interface returns
+** SQLITE_ERROR and if the specified column does not exist.
+** ^If the column-name parameter to sqlite3_table_column_metadata() is a
+** NULL pointer, then this routine simply checks for the existence of the
+** table and returns SQLITE_OK if the table exists and SQLITE_ERROR if it
+** does not.
+**
+** ^The column is identified by the second, third and fourth parameters to
+** this function. ^(The second parameter is either the name of the database
+** (i.e. "main", "temp", or an attached database) containing the specified
+** table or NULL.)^ ^If it is NULL, then all attached databases are searched
+** for the table using the same algorithm used by the database engine to
+** resolve unqualified table references.
+**
+** ^The third and fourth parameters to this function are the table and column
+** name of the desired column, respectively.
+**
+** ^Metadata is returned by writing to the memory locations passed as the 5th
+** and subsequent parameters to this function. ^Any of these arguments may be
+** NULL, in which case the corresponding element of metadata is omitted.
+**
+** ^(<blockquote>
+** <table border="1">
+** <tr><th> Parameter <th> Output<br>Type <th>  Description
+**
+** <tr><td> 5th <td> const char* <td> Data type
+** <tr><td> 6th <td> const char* <td> Name of default collation sequence
+** <tr><td> 7th <td> int         <td> True if column has a NOT NULL constraint
+** <tr><td> 8th <td> int         <td> True if column is part of the PRIMARY KEY
+** <tr><td> 9th <td> int         <td> True if column is [AUTOINCREMENT]
+** </table>
+** </blockquote>)^
+**
+** ^The memory pointed to by the character pointers returned for the
+** declaration type and collation sequence is valid until the next
+** call to any SQLite API function.
+**
+** ^If the specified table is actually a view, an [error code] is returned.
+**
+** ^If the specified column is "rowid", "oid" or "_rowid_" and the table 
+** is not a [WITHOUT ROWID] table and an
+** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output
+** parameters are set for the explicitly declared column. ^(If there is no
+** [INTEGER PRIMARY KEY] column, then the outputs
+** for the [rowid] are set as follows:
+**
+** <pre>
+**     data type: "INTEGER"
+**     collation sequence: "BINARY"
+**     not null: 0
+**     primary key: 1
+**     auto increment: 0
+** </pre>)^
+**
+** ^This function causes all database schemas to be read from disk and
+** parsed, if that has not already been done, and returns an error if
+** any errors are encountered while loading the schema.
+*/
+SQLITE_API int sqlite3_table_column_metadata(
+  sqlite3 *db,                /* Connection handle */
+  const char *zDbName,        /* Database name or NULL */
+  const char *zTableName,     /* Table name */
+  const char *zColumnName,    /* Column name */
+  char const **pzDataType,    /* OUTPUT: Declared data type */
+  char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
+  int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
+  int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
+  int *pAutoinc               /* OUTPUT: True if column is auto-increment */
+);
+
+/*
+** CAPI3REF: Load An Extension
+** METHOD: sqlite3
+**
+** ^This interface loads an SQLite extension library from the named file.
+**
+** ^The sqlite3_load_extension() interface attempts to load an
+** [SQLite extension] library contained in the file zFile.  If
+** the file cannot be loaded directly, attempts are made to load
+** with various operating-system specific extensions added.
+** So for example, if "samplelib" cannot be loaded, then names like
+** "samplelib.so" or "samplelib.dylib" or "samplelib.dll" might
+** be tried also.
+**
+** ^The entry point is zProc.
+** ^(zProc may be 0, in which case SQLite will try to come up with an
+** entry point name on its own.  It first tries "sqlite3_extension_init".
+** If that does not work, it constructs a name "sqlite3_X_init" where the
+** X is consists of the lower-case equivalent of all ASCII alphabetic
+** characters in the filename from the last "/" to the first following
+** "." and omitting any initial "lib".)^
+** ^The sqlite3_load_extension() interface returns
+** [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong.
+** ^If an error occurs and pzErrMsg is not 0, then the
+** [sqlite3_load_extension()] interface shall attempt to
+** fill *pzErrMsg with error message text stored in memory
+** obtained from [sqlite3_malloc()]. The calling function
+** should free this memory by calling [sqlite3_free()].
+**
+** ^Extension loading must be enabled using
+** [sqlite3_enable_load_extension()] or
+** [sqlite3_db_config](db,[SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION],1,NULL)
+** prior to calling this API,
+** otherwise an error will be returned.
+**
+** <b>Security warning:</b> It is recommended that the 
+** [SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION] method be used to enable only this
+** interface.  The use of the [sqlite3_enable_load_extension()] interface
+** should be avoided.  This will keep the SQL function [load_extension()]
+** disabled and prevent SQL injections from giving attackers
+** access to extension loading capabilities.
+**
+** See also the [load_extension() SQL function].
+*/
+SQLITE_API int sqlite3_load_extension(
+  sqlite3 *db,          /* Load the extension into this database connection */
+  const char *zFile,    /* Name of the shared library containing extension */
+  const char *zProc,    /* Entry point.  Derived from zFile if 0 */
+  char **pzErrMsg       /* Put error message here if not 0 */
+);
+
+/*
+** CAPI3REF: Enable Or Disable Extension Loading
+** METHOD: sqlite3
+**
+** ^So as not to open security holes in older applications that are
+** unprepared to deal with [extension loading], and as a means of disabling
+** [extension loading] while evaluating user-entered SQL, the following API
+** is provided to turn the [sqlite3_load_extension()] mechanism on and off.
+**
+** ^Extension loading is off by default.
+** ^Call the sqlite3_enable_load_extension() routine with onoff==1
+** to turn extension loading on and call it with onoff==0 to turn
+** it back off again.
+**
+** ^This interface enables or disables both the C-API
+** [sqlite3_load_extension()] and the SQL function [load_extension()].
+** ^(Use [sqlite3_db_config](db,[SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION],..)
+** to enable or disable only the C-API.)^
+**
+** <b>Security warning:</b> It is recommended that extension loading
+** be disabled using the [SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION] method
+** rather than this interface, so the [load_extension()] SQL function
+** remains disabled. This will prevent SQL injections from giving attackers
+** access to extension loading capabilities.
+*/
+SQLITE_API int sqlite3_enable_load_extension(sqlite3 *db, int onoff);
+
+/*
+** CAPI3REF: Automatically Load Statically Linked Extensions
+**
+** ^This interface causes the xEntryPoint() function to be invoked for
+** each new [database connection] that is created.  The idea here is that
+** xEntryPoint() is the entry point for a statically linked [SQLite extension]
+** that is to be automatically loaded into all new database connections.
+**
+** ^(Even though the function prototype shows that xEntryPoint() takes
+** no arguments and returns void, SQLite invokes xEntryPoint() with three
+** arguments and expects an integer result as if the signature of the
+** entry point where as follows:
+**
+** <blockquote><pre>
+** &nbsp;  int xEntryPoint(
+** &nbsp;    sqlite3 *db,
+** &nbsp;    const char **pzErrMsg,
+** &nbsp;    const struct sqlite3_api_routines *pThunk
+** &nbsp;  );
+** </pre></blockquote>)^
+**
+** If the xEntryPoint routine encounters an error, it should make *pzErrMsg
+** point to an appropriate error message (obtained from [sqlite3_mprintf()])
+** and return an appropriate [error code].  ^SQLite ensures that *pzErrMsg
+** is NULL before calling the xEntryPoint().  ^SQLite will invoke
+** [sqlite3_free()] on *pzErrMsg after xEntryPoint() returns.  ^If any
+** xEntryPoint() returns an error, the [sqlite3_open()], [sqlite3_open16()],
+** or [sqlite3_open_v2()] call that provoked the xEntryPoint() will fail.
+**
+** ^Calling sqlite3_auto_extension(X) with an entry point X that is already
+** on the list of automatic extensions is a harmless no-op. ^No entry point
+** will be called more than once for each database connection that is opened.
+**
+** See also: [sqlite3_reset_auto_extension()]
+** and [sqlite3_cancel_auto_extension()]
+*/
+SQLITE_API int sqlite3_auto_extension(void(*xEntryPoint)(void));
+
+/*
+** CAPI3REF: Cancel Automatic Extension Loading
+**
+** ^The [sqlite3_cancel_auto_extension(X)] interface unregisters the
+** initialization routine X that was registered using a prior call to
+** [sqlite3_auto_extension(X)].  ^The [sqlite3_cancel_auto_extension(X)]
+** routine returns 1 if initialization routine X was successfully 
+** unregistered and it returns 0 if X was not on the list of initialization
+** routines.
+*/
+SQLITE_API int sqlite3_cancel_auto_extension(void(*xEntryPoint)(void));
+
+/*
+** CAPI3REF: Reset Automatic Extension Loading
+**
+** ^This interface disables all automatic extensions previously
+** registered using [sqlite3_auto_extension()].
+*/
+SQLITE_API void sqlite3_reset_auto_extension(void);
+
+/*
+** The interface to the virtual-table mechanism is currently considered
+** to be experimental.  The interface might change in incompatible ways.
+** If this is a problem for you, do not use the interface at this time.
+**
+** When the virtual-table mechanism stabilizes, we will declare the
+** interface fixed, support it indefinitely, and remove this comment.
+*/
+
+/*
+** Structures used by the virtual table interface
+*/
+typedef struct sqlite3_vtab sqlite3_vtab;
+typedef struct sqlite3_index_info sqlite3_index_info;
+typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
+typedef struct sqlite3_module sqlite3_module;
+
+/*
+** CAPI3REF: Virtual Table Object
+** KEYWORDS: sqlite3_module {virtual table module}
+**
+** This structure, sometimes called a "virtual table module", 
+** defines the implementation of a [virtual tables].  
+** This structure consists mostly of methods for the module.
+**
+** ^A virtual table module is created by filling in a persistent
+** instance of this structure and passing a pointer to that instance
+** to [sqlite3_create_module()] or [sqlite3_create_module_v2()].
+** ^The registration remains valid until it is replaced by a different
+** module or until the [database connection] closes.  The content
+** of this structure must not change while it is registered with
+** any database connection.
+*/
+struct sqlite3_module {
+  int iVersion;
+  int (*xCreate)(sqlite3*, void *pAux,
+               int argc, const char *const*argv,
+               sqlite3_vtab **ppVTab, char**);
+  int (*xConnect)(sqlite3*, void *pAux,
+               int argc, const char *const*argv,
+               sqlite3_vtab **ppVTab, char**);
+  int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*);
+  int (*xDisconnect)(sqlite3_vtab *pVTab);
+  int (*xDestroy)(sqlite3_vtab *pVTab);
+  int (*xOpen)(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor);
+  int (*xClose)(sqlite3_vtab_cursor*);
+  int (*xFilter)(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
+                int argc, sqlite3_value **argv);
+  int (*xNext)(sqlite3_vtab_cursor*);
+  int (*xEof)(sqlite3_vtab_cursor*);
+  int (*xColumn)(sqlite3_vtab_cursor*, sqlite3_context*, int);
+  int (*xRowid)(sqlite3_vtab_cursor*, sqlite3_int64 *pRowid);
+  int (*xUpdate)(sqlite3_vtab *, int, sqlite3_value **, sqlite3_int64 *);
+  int (*xBegin)(sqlite3_vtab *pVTab);
+  int (*xSync)(sqlite3_vtab *pVTab);
+  int (*xCommit)(sqlite3_vtab *pVTab);
+  int (*xRollback)(sqlite3_vtab *pVTab);
+  int (*xFindFunction)(sqlite3_vtab *pVtab, int nArg, const char *zName,
+                       void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
+                       void **ppArg);
+  int (*xRename)(sqlite3_vtab *pVtab, const char *zNew);
+  /* The methods above are in version 1 of the sqlite_module object. Those 
+  ** below are for version 2 and greater. */
+  int (*xSavepoint)(sqlite3_vtab *pVTab, int);
+  int (*xRelease)(sqlite3_vtab *pVTab, int);
+  int (*xRollbackTo)(sqlite3_vtab *pVTab, int);
+};
+
+/*
+** CAPI3REF: Virtual Table Indexing Information
+** KEYWORDS: sqlite3_index_info
+**
+** The sqlite3_index_info structure and its substructures is used as part
+** of the [virtual table] interface to
+** pass information into and receive the reply from the [xBestIndex]
+** method of a [virtual table module].  The fields under **Inputs** are the
+** inputs to xBestIndex and are read-only.  xBestIndex inserts its
+** results into the **Outputs** fields.
+**
+** ^(The aConstraint[] array records WHERE clause constraints of the form:
+**
+** <blockquote>column OP expr</blockquote>
+**
+** where OP is =, &lt;, &lt;=, &gt;, or &gt;=.)^  ^(The particular operator is
+** stored in aConstraint[].op using one of the
+** [SQLITE_INDEX_CONSTRAINT_EQ | SQLITE_INDEX_CONSTRAINT_ values].)^
+** ^(The index of the column is stored in
+** aConstraint[].iColumn.)^  ^(aConstraint[].usable is TRUE if the
+** expr on the right-hand side can be evaluated (and thus the constraint
+** is usable) and false if it cannot.)^
+**
+** ^The optimizer automatically inverts terms of the form "expr OP column"
+** and makes other simplifications to the WHERE clause in an attempt to
+** get as many WHERE clause terms into the form shown above as possible.
+** ^The aConstraint[] array only reports WHERE clause terms that are
+** relevant to the particular virtual table being queried.
+**
+** ^Information about the ORDER BY clause is stored in aOrderBy[].
+** ^Each term of aOrderBy records a column of the ORDER BY clause.
+**
+** The colUsed field indicates which columns of the virtual table may be
+** required by the current scan. Virtual table columns are numbered from
+** zero in the order in which they appear within the CREATE TABLE statement
+** passed to sqlite3_declare_vtab(). For the first 63 columns (columns 0-62),
+** the corresponding bit is set within the colUsed mask if the column may be
+** required by SQLite. If the table has at least 64 columns and any column
+** to the right of the first 63 is required, then bit 63 of colUsed is also
+** set. In other words, column iCol may be required if the expression
+** (colUsed & ((sqlite3_uint64)1 << (iCol>=63 ? 63 : iCol))) evaluates to 
+** non-zero.
+**
+** The [xBestIndex] method must fill aConstraintUsage[] with information
+** about what parameters to pass to xFilter.  ^If argvIndex>0 then
+** the right-hand side of the corresponding aConstraint[] is evaluated
+** and becomes the argvIndex-th entry in argv.  ^(If aConstraintUsage[].omit
+** is true, then the constraint is assumed to be fully handled by the
+** virtual table and is not checked again by SQLite.)^
+**
+** ^The idxNum and idxPtr values are recorded and passed into the
+** [xFilter] method.
+** ^[sqlite3_free()] is used to free idxPtr if and only if
+** needToFreeIdxPtr is true.
+**
+** ^The orderByConsumed means that output from [xFilter]/[xNext] will occur in
+** the correct order to satisfy the ORDER BY clause so that no separate
+** sorting step is required.
+**
+** ^The estimatedCost value is an estimate of the cost of a particular
+** strategy. A cost of N indicates that the cost of the strategy is similar
+** to a linear scan of an SQLite table with N rows. A cost of log(N) 
+** indicates that the expense of the operation is similar to that of a
+** binary search on a unique indexed field of an SQLite table with N rows.
+**
+** ^The estimatedRows value is an estimate of the number of rows that
+** will be returned by the strategy.
+**
+** The xBestIndex method may optionally populate the idxFlags field with a 
+** mask of SQLITE_INDEX_SCAN_* flags. Currently there is only one such flag -
+** SQLITE_INDEX_SCAN_UNIQUE. If the xBestIndex method sets this flag, SQLite
+** assumes that the strategy may visit at most one row. 
+**
+** Additionally, if xBestIndex sets the SQLITE_INDEX_SCAN_UNIQUE flag, then
+** SQLite also assumes that if a call to the xUpdate() method is made as
+** part of the same statement to delete or update a virtual table row and the
+** implementation returns SQLITE_CONSTRAINT, then there is no need to rollback
+** any database changes. In other words, if the xUpdate() returns
+** SQLITE_CONSTRAINT, the database contents must be exactly as they were
+** before xUpdate was called. By contrast, if SQLITE_INDEX_SCAN_UNIQUE is not
+** set and xUpdate returns SQLITE_CONSTRAINT, any database changes made by
+** the xUpdate method are automatically rolled back by SQLite.
+**
+** IMPORTANT: The estimatedRows field was added to the sqlite3_index_info
+** structure for SQLite [version 3.8.2] ([dateof:3.8.2]). 
+** If a virtual table extension is
+** used with an SQLite version earlier than 3.8.2, the results of attempting 
+** to read or write the estimatedRows field are undefined (but are likely 
+** to included crashing the application). The estimatedRows field should
+** therefore only be used if [sqlite3_libversion_number()] returns a
+** value greater than or equal to 3008002. Similarly, the idxFlags field
+** was added for [version 3.9.0] ([dateof:3.9.0]). 
+** It may therefore only be used if
+** sqlite3_libversion_number() returns a value greater than or equal to
+** 3009000.
+*/
+struct sqlite3_index_info {
+  /* Inputs */
+  int nConstraint;           /* Number of entries in aConstraint */
+  struct sqlite3_index_constraint {
+     int iColumn;              /* Column constrained.  -1 for ROWID */
+     unsigned char op;         /* Constraint operator */
+     unsigned char usable;     /* True if this constraint is usable */
+     int iTermOffset;          /* Used internally - xBestIndex should ignore */
+  } *aConstraint;            /* Table of WHERE clause constraints */
+  int nOrderBy;              /* Number of terms in the ORDER BY clause */
+  struct sqlite3_index_orderby {
+     int iColumn;              /* Column number */
+     unsigned char desc;       /* True for DESC.  False for ASC. */
+  } *aOrderBy;               /* The ORDER BY clause */
+  /* Outputs */
+  struct sqlite3_index_constraint_usage {
+    int argvIndex;           /* if >0, constraint is part of argv to xFilter */
+    unsigned char omit;      /* Do not code a test for this constraint */
+  } *aConstraintUsage;
+  int idxNum;                /* Number used to identify the index */
+  char *idxStr;              /* String, possibly obtained from sqlite3_malloc */
+  int needToFreeIdxStr;      /* Free idxStr using sqlite3_free() if true */
+  int orderByConsumed;       /* True if output is already ordered */
+  double estimatedCost;           /* Estimated cost of using this index */
+  /* Fields below are only available in SQLite 3.8.2 and later */
+  sqlite3_int64 estimatedRows;    /* Estimated number of rows returned */
+  /* Fields below are only available in SQLite 3.9.0 and later */
+  int idxFlags;              /* Mask of SQLITE_INDEX_SCAN_* flags */
+  /* Fields below are only available in SQLite 3.10.0 and later */
+  sqlite3_uint64 colUsed;    /* Input: Mask of columns used by statement */
+};
+
+/*
+** CAPI3REF: Virtual Table Scan Flags
+*/
+#define SQLITE_INDEX_SCAN_UNIQUE      1     /* Scan visits at most 1 row */
+
+/*
+** CAPI3REF: Virtual Table Constraint Operator Codes
+**
+** These macros defined the allowed values for the
+** [sqlite3_index_info].aConstraint[].op field.  Each value represents
+** an operator that is part of a constraint term in the wHERE clause of
+** a query that uses a [virtual table].
+*/
+#define SQLITE_INDEX_CONSTRAINT_EQ      2
+#define SQLITE_INDEX_CONSTRAINT_GT      4
+#define SQLITE_INDEX_CONSTRAINT_LE      8
+#define SQLITE_INDEX_CONSTRAINT_LT     16
+#define SQLITE_INDEX_CONSTRAINT_GE     32
+#define SQLITE_INDEX_CONSTRAINT_MATCH  64
+#define SQLITE_INDEX_CONSTRAINT_LIKE   65
+#define SQLITE_INDEX_CONSTRAINT_GLOB   66
+#define SQLITE_INDEX_CONSTRAINT_REGEXP 67
+
+/*
+** CAPI3REF: Register A Virtual Table Implementation
+** METHOD: sqlite3
+**
+** ^These routines are used to register a new [virtual table module] name.
+** ^Module names must be registered before
+** creating a new [virtual table] using the module and before using a
+** preexisting [virtual table] for the module.
+**
+** ^The module name is registered on the [database connection] specified
+** by the first parameter.  ^The name of the module is given by the 
+** second parameter.  ^The third parameter is a pointer to
+** the implementation of the [virtual table module].   ^The fourth
+** parameter is an arbitrary client data pointer that is passed through
+** into the [xCreate] and [xConnect] methods of the virtual table module
+** when a new virtual table is be being created or reinitialized.
+**
+** ^The sqlite3_create_module_v2() interface has a fifth parameter which
+** is a pointer to a destructor for the pClientData.  ^SQLite will
+** invoke the destructor function (if it is not NULL) when SQLite
+** no longer needs the pClientData pointer.  ^The destructor will also
+** be invoked if the call to sqlite3_create_module_v2() fails.
+** ^The sqlite3_create_module()
+** interface is equivalent to sqlite3_create_module_v2() with a NULL
+** destructor.
+*/
+SQLITE_API int sqlite3_create_module(
+  sqlite3 *db,               /* SQLite connection to register module with */
+  const char *zName,         /* Name of the module */
+  const sqlite3_module *p,   /* Methods for the module */
+  void *pClientData          /* Client data for xCreate/xConnect */
+);
+SQLITE_API int sqlite3_create_module_v2(
+  sqlite3 *db,               /* SQLite connection to register module with */
+  const char *zName,         /* Name of the module */
+  const sqlite3_module *p,   /* Methods for the module */
+  void *pClientData,         /* Client data for xCreate/xConnect */
+  void(*xDestroy)(void*)     /* Module destructor function */
+);
+
+/*
+** CAPI3REF: Virtual Table Instance Object
+** KEYWORDS: sqlite3_vtab
+**
+** Every [virtual table module] implementation uses a subclass
+** of this object to describe a particular instance
+** of the [virtual table].  Each subclass will
+** be tailored to the specific needs of the module implementation.
+** The purpose of this superclass is to define certain fields that are
+** common to all module implementations.
+**
+** ^Virtual tables methods can set an error message by assigning a
+** string obtained from [sqlite3_mprintf()] to zErrMsg.  The method should
+** take care that any prior string is freed by a call to [sqlite3_free()]
+** prior to assigning a new string to zErrMsg.  ^After the error message
+** is delivered up to the client application, the string will be automatically
+** freed by sqlite3_free() and the zErrMsg field will be zeroed.
+*/
+struct sqlite3_vtab {
+  const sqlite3_module *pModule;  /* The module for this virtual table */
+  int nRef;                       /* Number of open cursors */
+  char *zErrMsg;                  /* Error message from sqlite3_mprintf() */
+  /* Virtual table implementations will typically add additional fields */
+};
+
+/*
+** CAPI3REF: Virtual Table Cursor Object
+** KEYWORDS: sqlite3_vtab_cursor {virtual table cursor}
+**
+** Every [virtual table module] implementation uses a subclass of the
+** following structure to describe cursors that point into the
+** [virtual table] and are used
+** to loop through the virtual table.  Cursors are created using the
+** [sqlite3_module.xOpen | xOpen] method of the module and are destroyed
+** by the [sqlite3_module.xClose | xClose] method.  Cursors are used
+** by the [xFilter], [xNext], [xEof], [xColumn], and [xRowid] methods
+** of the module.  Each module implementation will define
+** the content of a cursor structure to suit its own needs.
+**
+** This superclass exists in order to define fields of the cursor that
+** are common to all implementations.
+*/
+struct sqlite3_vtab_cursor {
+  sqlite3_vtab *pVtab;      /* Virtual table of this cursor */
+  /* Virtual table implementations will typically add additional fields */
+};
+
+/*
+** CAPI3REF: Declare The Schema Of A Virtual Table
+**
+** ^The [xCreate] and [xConnect] methods of a
+** [virtual table module] call this interface
+** to declare the format (the names and datatypes of the columns) of
+** the virtual tables they implement.
+*/
+SQLITE_API int sqlite3_declare_vtab(sqlite3*, const char *zSQL);
+
+/*
+** CAPI3REF: Overload A Function For A Virtual Table
+** METHOD: sqlite3
+**
+** ^(Virtual tables can provide alternative implementations of functions
+** using the [xFindFunction] method of the [virtual table module].  
+** But global versions of those functions
+** must exist in order to be overloaded.)^
+**
+** ^(This API makes sure a global version of a function with a particular
+** name and number of parameters exists.  If no such function exists
+** before this API is called, a new function is created.)^  ^The implementation
+** of the new function always causes an exception to be thrown.  So
+** the new function is not good for anything by itself.  Its only
+** purpose is to be a placeholder function that can be overloaded
+** by a [virtual table].
+*/
+SQLITE_API int sqlite3_overload_function(sqlite3*, const char *zFuncName, int nArg);
+
+/*
+** The interface to the virtual-table mechanism defined above (back up
+** to a comment remarkably similar to this one) is currently considered
+** to be experimental.  The interface might change in incompatible ways.
+** If this is a problem for you, do not use the interface at this time.
+**
+** When the virtual-table mechanism stabilizes, we will declare the
+** interface fixed, support it indefinitely, and remove this comment.
+*/
+
+/*
+** CAPI3REF: A Handle To An Open BLOB
+** KEYWORDS: {BLOB handle} {BLOB handles}
+**
+** An instance of this object represents an open BLOB on which
+** [sqlite3_blob_open | incremental BLOB I/O] can be performed.
+** ^Objects of this type are created by [sqlite3_blob_open()]
+** and destroyed by [sqlite3_blob_close()].
+** ^The [sqlite3_blob_read()] and [sqlite3_blob_write()] interfaces
+** can be used to read or write small subsections of the BLOB.
+** ^The [sqlite3_blob_bytes()] interface returns the size of the BLOB in bytes.
+*/
+typedef struct sqlite3_blob sqlite3_blob;
+
+/*
+** CAPI3REF: Open A BLOB For Incremental I/O
+** METHOD: sqlite3
+** CONSTRUCTOR: sqlite3_blob
+**
+** ^(This interfaces opens a [BLOB handle | handle] to the BLOB located
+** in row iRow, column zColumn, table zTable in database zDb;
+** in other words, the same BLOB that would be selected by:
+**
+** <pre>
+**     SELECT zColumn FROM zDb.zTable WHERE [rowid] = iRow;
+** </pre>)^
+**
+** ^(Parameter zDb is not the filename that contains the database, but 
+** rather the symbolic name of the database. For attached databases, this is
+** the name that appears after the AS keyword in the [ATTACH] statement.
+** For the main database file, the database name is "main". For TEMP
+** tables, the database name is "temp".)^
+**
+** ^If the flags parameter is non-zero, then the BLOB is opened for read
+** and write access. ^If the flags parameter is zero, the BLOB is opened for
+** read-only access.
+**
+** ^(On success, [SQLITE_OK] is returned and the new [BLOB handle] is stored
+** in *ppBlob. Otherwise an [error code] is returned and, unless the error
+** code is SQLITE_MISUSE, *ppBlob is set to NULL.)^ ^This means that, provided
+** the API is not misused, it is always safe to call [sqlite3_blob_close()] 
+** on *ppBlob after this function it returns.
+**
+** This function fails with SQLITE_ERROR if any of the following are true:
+** <ul>
+**   <li> ^(Database zDb does not exist)^, 
+**   <li> ^(Table zTable does not exist within database zDb)^, 
+**   <li> ^(Table zTable is a WITHOUT ROWID table)^, 
+**   <li> ^(Column zColumn does not exist)^,
+**   <li> ^(Row iRow is not present in the table)^,
+**   <li> ^(The specified column of row iRow contains a value that is not
+**         a TEXT or BLOB value)^,
+**   <li> ^(Column zColumn is part of an index, PRIMARY KEY or UNIQUE 
+**         constraint and the blob is being opened for read/write access)^,
+**   <li> ^([foreign key constraints | Foreign key constraints] are enabled, 
+**         column zColumn is part of a [child key] definition and the blob is
+**         being opened for read/write access)^.
+** </ul>
+**
+** ^Unless it returns SQLITE_MISUSE, this function sets the 
+** [database connection] error code and message accessible via 
+** [sqlite3_errcode()] and [sqlite3_errmsg()] and related functions. 
+**
+**
+** ^(If the row that a BLOB handle points to is modified by an
+** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
+** then the BLOB handle is marked as "expired".
+** This is true if any column of the row is changed, even a column
+** other than the one the BLOB handle is open on.)^
+** ^Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for
+** an expired BLOB handle fail with a return code of [SQLITE_ABORT].
+** ^(Changes written into a BLOB prior to the BLOB expiring are not
+** rolled back by the expiration of the BLOB.  Such changes will eventually
+** commit if the transaction continues to completion.)^
+**
+** ^Use the [sqlite3_blob_bytes()] interface to determine the size of
+** the opened blob.  ^The size of a blob may not be changed by this
+** interface.  Use the [UPDATE] SQL command to change the size of a
+** blob.
+**
+** ^The [sqlite3_bind_zeroblob()] and [sqlite3_result_zeroblob()] interfaces
+** and the built-in [zeroblob] SQL function may be used to create a 
+** zero-filled blob to read or write using the incremental-blob interface.
+**
+** To avoid a resource leak, every open [BLOB handle] should eventually
+** be released by a call to [sqlite3_blob_close()].
+*/
+SQLITE_API int sqlite3_blob_open(
+  sqlite3*,
+  const char *zDb,
+  const char *zTable,
+  const char *zColumn,
+  sqlite3_int64 iRow,
+  int flags,
+  sqlite3_blob **ppBlob
+);
+
+/*
+** CAPI3REF: Move a BLOB Handle to a New Row
+** METHOD: sqlite3_blob
+**
+** ^This function is used to move an existing blob handle so that it points
+** to a different row of the same database table. ^The new row is identified
+** by the rowid value passed as the second argument. Only the row can be
+** changed. ^The database, table and column on which the blob handle is open
+** remain the same. Moving an existing blob handle to a new row can be
+** faster than closing the existing handle and opening a new one.
+**
+** ^(The new row must meet the same criteria as for [sqlite3_blob_open()] -
+** it must exist and there must be either a blob or text value stored in
+** the nominated column.)^ ^If the new row is not present in the table, or if
+** it does not contain a blob or text value, or if another error occurs, an
+** SQLite error code is returned and the blob handle is considered aborted.
+** ^All subsequent calls to [sqlite3_blob_read()], [sqlite3_blob_write()] or
+** [sqlite3_blob_reopen()] on an aborted blob handle immediately return
+** SQLITE_ABORT. ^Calling [sqlite3_blob_bytes()] on an aborted blob handle
+** always returns zero.
+**
+** ^This function sets the database handle error code and message.
+*/
+SQLITE_API int sqlite3_blob_reopen(sqlite3_blob *, sqlite3_int64);
+
+/*
+** CAPI3REF: Close A BLOB Handle
+** DESTRUCTOR: sqlite3_blob
+**
+** ^This function closes an open [BLOB handle]. ^(The BLOB handle is closed
+** unconditionally.  Even if this routine returns an error code, the 
+** handle is still closed.)^
+**
+** ^If the blob handle being closed was opened for read-write access, and if
+** the database is in auto-commit mode and there are no other open read-write
+** blob handles or active write statements, the current transaction is
+** committed. ^If an error occurs while committing the transaction, an error
+** code is returned and the transaction rolled back.
+**
+** Calling this function with an argument that is not a NULL pointer or an
+** open blob handle results in undefined behaviour. ^Calling this routine 
+** with a null pointer (such as would be returned by a failed call to 
+** [sqlite3_blob_open()]) is a harmless no-op. ^Otherwise, if this function
+** is passed a valid open blob handle, the values returned by the 
+** sqlite3_errcode() and sqlite3_errmsg() functions are set before returning.
+*/
+SQLITE_API int sqlite3_blob_close(sqlite3_blob *);
+
+/*
+** CAPI3REF: Return The Size Of An Open BLOB
+** METHOD: sqlite3_blob
+**
+** ^Returns the size in bytes of the BLOB accessible via the 
+** successfully opened [BLOB handle] in its only argument.  ^The
+** incremental blob I/O routines can only read or overwriting existing
+** blob content; they cannot change the size of a blob.
+**
+** This routine only works on a [BLOB handle] which has been created
+** by a prior successful call to [sqlite3_blob_open()] and which has not
+** been closed by [sqlite3_blob_close()].  Passing any other pointer in
+** to this routine results in undefined and probably undesirable behavior.
+*/
+SQLITE_API int sqlite3_blob_bytes(sqlite3_blob *);
+
+/*
+** CAPI3REF: Read Data From A BLOB Incrementally
+** METHOD: sqlite3_blob
+**
+** ^(This function is used to read data from an open [BLOB handle] into a
+** caller-supplied buffer. N bytes of data are copied into buffer Z
+** from the open BLOB, starting at offset iOffset.)^
+**
+** ^If offset iOffset is less than N bytes from the end of the BLOB,
+** [SQLITE_ERROR] is returned and no data is read.  ^If N or iOffset is
+** less than zero, [SQLITE_ERROR] is returned and no data is read.
+** ^The size of the blob (and hence the maximum value of N+iOffset)
+** can be determined using the [sqlite3_blob_bytes()] interface.
+**
+** ^An attempt to read from an expired [BLOB handle] fails with an
+** error code of [SQLITE_ABORT].
+**
+** ^(On success, sqlite3_blob_read() returns SQLITE_OK.
+** Otherwise, an [error code] or an [extended error code] is returned.)^
+**
+** This routine only works on a [BLOB handle] which has been created
+** by a prior successful call to [sqlite3_blob_open()] and which has not
+** been closed by [sqlite3_blob_close()].  Passing any other pointer in
+** to this routine results in undefined and probably undesirable behavior.
+**
+** See also: [sqlite3_blob_write()].
+*/
+SQLITE_API int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);
+
+/*
+** CAPI3REF: Write Data Into A BLOB Incrementally
+** METHOD: sqlite3_blob
+**
+** ^(This function is used to write data into an open [BLOB handle] from a
+** caller-supplied buffer. N bytes of data are copied from the buffer Z
+** into the open BLOB, starting at offset iOffset.)^
+**
+** ^(On success, sqlite3_blob_write() returns SQLITE_OK.
+** Otherwise, an  [error code] or an [extended error code] is returned.)^
+** ^Unless SQLITE_MISUSE is returned, this function sets the 
+** [database connection] error code and message accessible via 
+** [sqlite3_errcode()] and [sqlite3_errmsg()] and related functions. 
+**
+** ^If the [BLOB handle] passed as the first argument was not opened for
+** writing (the flags parameter to [sqlite3_blob_open()] was zero),
+** this function returns [SQLITE_READONLY].
+**
+** This function may only modify the contents of the BLOB; it is
+** not possible to increase the size of a BLOB using this API.
+** ^If offset iOffset is less than N bytes from the end of the BLOB,
+** [SQLITE_ERROR] is returned and no data is written. The size of the 
+** BLOB (and hence the maximum value of N+iOffset) can be determined 
+** using the [sqlite3_blob_bytes()] interface. ^If N or iOffset are less 
+** than zero [SQLITE_ERROR] is returned and no data is written.
+**
+** ^An attempt to write to an expired [BLOB handle] fails with an
+** error code of [SQLITE_ABORT].  ^Writes to the BLOB that occurred
+** before the [BLOB handle] expired are not rolled back by the
+** expiration of the handle, though of course those changes might
+** have been overwritten by the statement that expired the BLOB handle
+** or by other independent statements.
+**
+** This routine only works on a [BLOB handle] which has been created
+** by a prior successful call to [sqlite3_blob_open()] and which has not
+** been closed by [sqlite3_blob_close()].  Passing any other pointer in
+** to this routine results in undefined and probably undesirable behavior.
+**
+** See also: [sqlite3_blob_read()].
+*/
+SQLITE_API int sqlite3_blob_write(sqlite3_blob *, const void *z, int n, int iOffset);
+
+/*
+** CAPI3REF: Virtual File System Objects
+**
+** A virtual filesystem (VFS) is an [sqlite3_vfs] object
+** that SQLite uses to interact
+** with the underlying operating system.  Most SQLite builds come with a
+** single default VFS that is appropriate for the host computer.
+** New VFSes can be registered and existing VFSes can be unregistered.
+** The following interfaces are provided.
+**
+** ^The sqlite3_vfs_find() interface returns a pointer to a VFS given its name.
+** ^Names are case sensitive.
+** ^Names are zero-terminated UTF-8 strings.
+** ^If there is no match, a NULL pointer is returned.
+** ^If zVfsName is NULL then the default VFS is returned.
+**
+** ^New VFSes are registered with sqlite3_vfs_register().
+** ^Each new VFS becomes the default VFS if the makeDflt flag is set.
+** ^The same VFS can be registered multiple times without injury.
+** ^To make an existing VFS into the default VFS, register it again
+** with the makeDflt flag set.  If two different VFSes with the
+** same name are registered, the behavior is undefined.  If a
+** VFS is registered with a name that is NULL or an empty string,
+** then the behavior is undefined.
+**
+** ^Unregister a VFS with the sqlite3_vfs_unregister() interface.
+** ^(If the default VFS is unregistered, another VFS is chosen as
+** the default.  The choice for the new VFS is arbitrary.)^
+*/
+SQLITE_API sqlite3_vfs *sqlite3_vfs_find(const char *zVfsName);
+SQLITE_API int sqlite3_vfs_register(sqlite3_vfs*, int makeDflt);
+SQLITE_API int sqlite3_vfs_unregister(sqlite3_vfs*);
+
+/*
+** CAPI3REF: Mutexes
+**
+** The SQLite core uses these routines for thread
+** synchronization. Though they are intended for internal
+** use by SQLite, code that links against SQLite is
+** permitted to use any of these routines.
+**
+** The SQLite source code contains multiple implementations
+** of these mutex routines.  An appropriate implementation
+** is selected automatically at compile-time.  The following
+** implementations are available in the SQLite core:
+**
+** <ul>
+** <li>   SQLITE_MUTEX_PTHREADS
+** <li>   SQLITE_MUTEX_W32
+** <li>   SQLITE_MUTEX_NOOP
+** </ul>
+**
+** The SQLITE_MUTEX_NOOP implementation is a set of routines
+** that does no real locking and is appropriate for use in
+** a single-threaded application.  The SQLITE_MUTEX_PTHREADS and
+** SQLITE_MUTEX_W32 implementations are appropriate for use on Unix
+** and Windows.
+**
+** If SQLite is compiled with the SQLITE_MUTEX_APPDEF preprocessor
+** macro defined (with "-DSQLITE_MUTEX_APPDEF=1"), then no mutex
+** implementation is included with the library. In this case the
+** application must supply a custom mutex implementation using the
+** [SQLITE_CONFIG_MUTEX] option of the sqlite3_config() function
+** before calling sqlite3_initialize() or any other public sqlite3_
+** function that calls sqlite3_initialize().
+**
+** ^The sqlite3_mutex_alloc() routine allocates a new
+** mutex and returns a pointer to it. ^The sqlite3_mutex_alloc()
+** routine returns NULL if it is unable to allocate the requested
+** mutex.  The argument to sqlite3_mutex_alloc() must one of these
+** integer constants:
+**
+** <ul>
+** <li>  SQLITE_MUTEX_FAST
+** <li>  SQLITE_MUTEX_RECURSIVE
+** <li>  SQLITE_MUTEX_STATIC_MASTER
+** <li>  SQLITE_MUTEX_STATIC_MEM
+** <li>  SQLITE_MUTEX_STATIC_OPEN
+** <li>  SQLITE_MUTEX_STATIC_PRNG
+** <li>  SQLITE_MUTEX_STATIC_LRU
+** <li>  SQLITE_MUTEX_STATIC_PMEM
+** <li>  SQLITE_MUTEX_STATIC_APP1
+** <li>  SQLITE_MUTEX_STATIC_APP2
+** <li>  SQLITE_MUTEX_STATIC_APP3
+** <li>  SQLITE_MUTEX_STATIC_VFS1
+** <li>  SQLITE_MUTEX_STATIC_VFS2
+** <li>  SQLITE_MUTEX_STATIC_VFS3
+** </ul>
+**
+** ^The first two constants (SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE)
+** cause sqlite3_mutex_alloc() to create
+** a new mutex.  ^The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
+** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
+** The mutex implementation does not need to make a distinction
+** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
+** not want to.  SQLite will only request a recursive mutex in
+** cases where it really needs one.  If a faster non-recursive mutex
+** implementation is available on the host platform, the mutex subsystem
+** might return such a mutex in response to SQLITE_MUTEX_FAST.
+**
+** ^The other allowed parameters to sqlite3_mutex_alloc() (anything other
+** than SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE) each return
+** a pointer to a static preexisting mutex.  ^Nine static mutexes are
+** used by the current version of SQLite.  Future versions of SQLite
+** may add additional static mutexes.  Static mutexes are for internal
+** use by SQLite only.  Applications that use SQLite mutexes should
+** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
+** SQLITE_MUTEX_RECURSIVE.
+**
+** ^Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
+** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
+** returns a different mutex on every call.  ^For the static
+** mutex types, the same mutex is returned on every call that has
+** the same type number.
+**
+** ^The sqlite3_mutex_free() routine deallocates a previously
+** allocated dynamic mutex.  Attempting to deallocate a static
+** mutex results in undefined behavior.
+**
+** ^The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
+** to enter a mutex.  ^If another thread is already within the mutex,
+** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
+** SQLITE_BUSY.  ^The sqlite3_mutex_try() interface returns [SQLITE_OK]
+** upon successful entry.  ^(Mutexes created using
+** SQLITE_MUTEX_RECURSIVE can be entered multiple times by the same thread.
+** In such cases, the
+** mutex must be exited an equal number of times before another thread
+** can enter.)^  If the same thread tries to enter any mutex other
+** than an SQLITE_MUTEX_RECURSIVE more than once, the behavior is undefined.
+**
+** ^(Some systems (for example, Windows 95) do not support the operation
+** implemented by sqlite3_mutex_try().  On those systems, sqlite3_mutex_try()
+** will always return SQLITE_BUSY. The SQLite core only ever uses
+** sqlite3_mutex_try() as an optimization so this is acceptable 
+** behavior.)^
+**
+** ^The sqlite3_mutex_leave() routine exits a mutex that was
+** previously entered by the same thread.   The behavior
+** is undefined if the mutex is not currently entered by the
+** calling thread or is not currently allocated.
+**
+** ^If the argument to sqlite3_mutex_enter(), sqlite3_mutex_try(), or
+** sqlite3_mutex_leave() is a NULL pointer, then all three routines
+** behave as no-ops.
+**
+** See also: [sqlite3_mutex_held()] and [sqlite3_mutex_notheld()].
+*/
+SQLITE_API sqlite3_mutex *sqlite3_mutex_alloc(int);
+SQLITE_API void sqlite3_mutex_free(sqlite3_mutex*);
+SQLITE_API void sqlite3_mutex_enter(sqlite3_mutex*);
+SQLITE_API int sqlite3_mutex_try(sqlite3_mutex*);
+SQLITE_API void sqlite3_mutex_leave(sqlite3_mutex*);
+
+/*
+** CAPI3REF: Mutex Methods Object
+**
+** An instance of this structure defines the low-level routines
+** used to allocate and use mutexes.
+**
+** Usually, the default mutex implementations provided by SQLite are
+** sufficient, however the application has the option of substituting a custom
+** implementation for specialized deployments or systems for which SQLite
+** does not provide a suitable implementation. In this case, the application
+** creates and populates an instance of this structure to pass
+** to sqlite3_config() along with the [SQLITE_CONFIG_MUTEX] option.
+** Additionally, an instance of this structure can be used as an
+** output variable when querying the system for the current mutex
+** implementation, using the [SQLITE_CONFIG_GETMUTEX] option.
+**
+** ^The xMutexInit method defined by this structure is invoked as
+** part of system initialization by the sqlite3_initialize() function.
+** ^The xMutexInit routine is called by SQLite exactly once for each
+** effective call to [sqlite3_initialize()].
+**
+** ^The xMutexEnd method defined by this structure is invoked as
+** part of system shutdown by the sqlite3_shutdown() function. The
+** implementation of this method is expected to release all outstanding
+** resources obtained by the mutex methods implementation, especially
+** those obtained by the xMutexInit method.  ^The xMutexEnd()
+** interface is invoked exactly once for each call to [sqlite3_shutdown()].
+**
+** ^(The remaining seven methods defined by this structure (xMutexAlloc,
+** xMutexFree, xMutexEnter, xMutexTry, xMutexLeave, xMutexHeld and
+** xMutexNotheld) implement the following interfaces (respectively):
+**
+** <ul>
+**   <li>  [sqlite3_mutex_alloc()] </li>
+**   <li>  [sqlite3_mutex_free()] </li>
+**   <li>  [sqlite3_mutex_enter()] </li>
+**   <li>  [sqlite3_mutex_try()] </li>
+**   <li>  [sqlite3_mutex_leave()] </li>
+**   <li>  [sqlite3_mutex_held()] </li>
+**   <li>  [sqlite3_mutex_notheld()] </li>
+** </ul>)^
+**
+** The only difference is that the public sqlite3_XXX functions enumerated
+** above silently ignore any invocations that pass a NULL pointer instead
+** of a valid mutex handle. The implementations of the methods defined
+** by this structure are not required to handle this case, the results
+** of passing a NULL pointer instead of a valid mutex handle are undefined
+** (i.e. it is acceptable to provide an implementation that segfaults if
+** it is passed a NULL pointer).
+**
+** The xMutexInit() method must be threadsafe.  It must be harmless to
+** invoke xMutexInit() multiple times within the same process and without
+** intervening calls to xMutexEnd().  Second and subsequent calls to
+** xMutexInit() must be no-ops.
+**
+** xMutexInit() must not use SQLite memory allocation ([sqlite3_malloc()]
+** and its associates).  Similarly, xMutexAlloc() must not use SQLite memory
+** allocation for a static mutex.  ^However xMutexAlloc() may use SQLite
+** memory allocation for a fast or recursive mutex.
+**
+** ^SQLite will invoke the xMutexEnd() method when [sqlite3_shutdown()] is
+** called, but only if the prior call to xMutexInit returned SQLITE_OK.
+** If xMutexInit fails in any way, it is expected to clean up after itself
+** prior to returning.
+*/
+typedef struct sqlite3_mutex_methods sqlite3_mutex_methods;
+struct sqlite3_mutex_methods {
+  int (*xMutexInit)(void);
+  int (*xMutexEnd)(void);
+  sqlite3_mutex *(*xMutexAlloc)(int);
+  void (*xMutexFree)(sqlite3_mutex *);
+  void (*xMutexEnter)(sqlite3_mutex *);
+  int (*xMutexTry)(sqlite3_mutex *);
+  void (*xMutexLeave)(sqlite3_mutex *);
+  int (*xMutexHeld)(sqlite3_mutex *);
+  int (*xMutexNotheld)(sqlite3_mutex *);
+};
+
+/*
+** CAPI3REF: Mutex Verification Routines
+**
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routines
+** are intended for use inside assert() statements.  The SQLite core
+** never uses these routines except inside an assert() and applications
+** are advised to follow the lead of the core.  The SQLite core only
+** provides implementations for these routines when it is compiled
+** with the SQLITE_DEBUG flag.  External mutex implementations
+** are only required to provide these routines if SQLITE_DEBUG is
+** defined and if NDEBUG is not defined.
+**
+** These routines should return true if the mutex in their argument
+** is held or not held, respectively, by the calling thread.
+**
+** The implementation is not required to provide versions of these
+** routines that actually work. If the implementation does not provide working
+** versions of these routines, it should at least provide stubs that always
+** return true so that one does not get spurious assertion failures.
+**
+** If the argument to sqlite3_mutex_held() is a NULL pointer then
+** the routine should return 1.   This seems counter-intuitive since
+** clearly the mutex cannot be held if it does not exist.  But
+** the reason the mutex does not exist is because the build is not
+** using mutexes.  And we do not want the assert() containing the
+** call to sqlite3_mutex_held() to fail, so a non-zero return is
+** the appropriate thing to do.  The sqlite3_mutex_notheld()
+** interface should also return 1 when given a NULL pointer.
+*/
+#ifndef NDEBUG
+SQLITE_API int sqlite3_mutex_held(sqlite3_mutex*);
+SQLITE_API int sqlite3_mutex_notheld(sqlite3_mutex*);
+#endif
+
+/*
+** CAPI3REF: Mutex Types
+**
+** The [sqlite3_mutex_alloc()] interface takes a single argument
+** which is one of these integer constants.
+**
+** The set of static mutexes may change from one SQLite release to the
+** next.  Applications that override the built-in mutex logic must be
+** prepared to accommodate additional static mutexes.
+*/
+#define SQLITE_MUTEX_FAST             0
+#define SQLITE_MUTEX_RECURSIVE        1
+#define SQLITE_MUTEX_STATIC_MASTER    2
+#define SQLITE_MUTEX_STATIC_MEM       3  /* sqlite3_malloc() */
+#define SQLITE_MUTEX_STATIC_MEM2      4  /* NOT USED */
+#define SQLITE_MUTEX_STATIC_OPEN      4  /* sqlite3BtreeOpen() */
+#define SQLITE_MUTEX_STATIC_PRNG      5  /* sqlite3_randomness() */
+#define SQLITE_MUTEX_STATIC_LRU       6  /* lru page list */
+#define SQLITE_MUTEX_STATIC_LRU2      7  /* NOT USED */
+#define SQLITE_MUTEX_STATIC_PMEM      7  /* sqlite3PageMalloc() */
+#define SQLITE_MUTEX_STATIC_APP1      8  /* For use by application */
+#define SQLITE_MUTEX_STATIC_APP2      9  /* For use by application */
+#define SQLITE_MUTEX_STATIC_APP3     10  /* For use by application */
+#define SQLITE_MUTEX_STATIC_VFS1     11  /* For use by built-in VFS */
+#define SQLITE_MUTEX_STATIC_VFS2     12  /* For use by extension VFS */
+#define SQLITE_MUTEX_STATIC_VFS3     13  /* For use by application VFS */
+
+/*
+** CAPI3REF: Retrieve the mutex for a database connection
+** METHOD: sqlite3
+**
+** ^This interface returns a pointer the [sqlite3_mutex] object that 
+** serializes access to the [database connection] given in the argument
+** when the [threading mode] is Serialized.
+** ^If the [threading mode] is Single-thread or Multi-thread then this
+** routine returns a NULL pointer.
+*/
+SQLITE_API sqlite3_mutex *sqlite3_db_mutex(sqlite3*);
+
+/*
+** CAPI3REF: Low-Level Control Of Database Files
+** METHOD: sqlite3
+**
+** ^The [sqlite3_file_control()] interface makes a direct call to the
+** xFileControl method for the [sqlite3_io_methods] object associated
+** with a particular database identified by the second argument. ^The
+** name of the database is "main" for the main database or "temp" for the
+** TEMP database, or the name that appears after the AS keyword for
+** databases that are added using the [ATTACH] SQL command.
+** ^A NULL pointer can be used in place of "main" to refer to the
+** main database file.
+** ^The third and fourth parameters to this routine
+** are passed directly through to the second and third parameters of
+** the xFileControl method.  ^The return value of the xFileControl
+** method becomes the return value of this routine.
+**
+** ^The SQLITE_FCNTL_FILE_POINTER value for the op parameter causes
+** a pointer to the underlying [sqlite3_file] object to be written into
+** the space pointed to by the 4th parameter.  ^The SQLITE_FCNTL_FILE_POINTER
+** case is a short-circuit path which does not actually invoke the
+** underlying sqlite3_io_methods.xFileControl method.
+**
+** ^If the second parameter (zDbName) does not match the name of any
+** open database file, then SQLITE_ERROR is returned.  ^This error
+** code is not remembered and will not be recalled by [sqlite3_errcode()]
+** or [sqlite3_errmsg()].  The underlying xFileControl method might
+** also return SQLITE_ERROR.  There is no way to distinguish between
+** an incorrect zDbName and an SQLITE_ERROR return from the underlying
+** xFileControl method.
+**
+** See also: [SQLITE_FCNTL_LOCKSTATE]
+*/
+SQLITE_API int sqlite3_file_control(sqlite3*, const char *zDbName, int op, void*);
+
+/*
+** CAPI3REF: Testing Interface
+**
+** ^The sqlite3_test_control() interface is used to read out internal
+** state of SQLite and to inject faults into SQLite for testing
+** purposes.  ^The first parameter is an operation code that determines
+** the number, meaning, and operation of all subsequent parameters.
+**
+** This interface is not for use by applications.  It exists solely
+** for verifying the correct operation of the SQLite library.  Depending
+** on how the SQLite library is compiled, this interface might not exist.
+**
+** The details of the operation codes, their meanings, the parameters
+** they take, and what they do are all subject to change without notice.
+** Unlike most of the SQLite API, this function is not guaranteed to
+** operate consistently from one release to the next.
+*/
+SQLITE_API int sqlite3_test_control(int op, ...);
+
+/*
+** CAPI3REF: Testing Interface Operation Codes
+**
+** These constants are the valid operation code parameters used
+** as the first argument to [sqlite3_test_control()].
+**
+** These parameters and their meanings are subject to change
+** without notice.  These values are for testing purposes only.
+** Applications should not use any of these parameters or the
+** [sqlite3_test_control()] interface.
+*/
+#define SQLITE_TESTCTRL_FIRST                    5
+#define SQLITE_TESTCTRL_PRNG_SAVE                5
+#define SQLITE_TESTCTRL_PRNG_RESTORE             6
+#define SQLITE_TESTCTRL_PRNG_RESET               7
+#define SQLITE_TESTCTRL_BITVEC_TEST              8
+#define SQLITE_TESTCTRL_FAULT_INSTALL            9
+#define SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS     10
+#define SQLITE_TESTCTRL_PENDING_BYTE            11
+#define SQLITE_TESTCTRL_ASSERT                  12
+#define SQLITE_TESTCTRL_ALWAYS                  13
+#define SQLITE_TESTCTRL_RESERVE                 14
+#define SQLITE_TESTCTRL_OPTIMIZATIONS           15
+#define SQLITE_TESTCTRL_ISKEYWORD               16
+#define SQLITE_TESTCTRL_SCRATCHMALLOC           17
+#define SQLITE_TESTCTRL_LOCALTIME_FAULT         18
+#define SQLITE_TESTCTRL_EXPLAIN_STMT            19  /* NOT USED */
+#define SQLITE_TESTCTRL_ONCE_RESET_THRESHOLD    19
+#define SQLITE_TESTCTRL_NEVER_CORRUPT           20
+#define SQLITE_TESTCTRL_VDBE_COVERAGE           21
+#define SQLITE_TESTCTRL_BYTEORDER               22
+#define SQLITE_TESTCTRL_ISINIT                  23
+#define SQLITE_TESTCTRL_SORTER_MMAP             24
+#define SQLITE_TESTCTRL_IMPOSTER                25
+#define SQLITE_TESTCTRL_LAST                    25
+
+/*
+** CAPI3REF: SQLite Runtime Status
+**
+** ^These interfaces are used to retrieve runtime status information
+** about the performance of SQLite, and optionally to reset various
+** highwater marks.  ^The first argument is an integer code for
+** the specific parameter to measure.  ^(Recognized integer codes
+** are of the form [status parameters | SQLITE_STATUS_...].)^
+** ^The current value of the parameter is returned into *pCurrent.
+** ^The highest recorded value is returned in *pHighwater.  ^If the
+** resetFlag is true, then the highest record value is reset after
+** *pHighwater is written.  ^(Some parameters do not record the highest
+** value.  For those parameters
+** nothing is written into *pHighwater and the resetFlag is ignored.)^
+** ^(Other parameters record only the highwater mark and not the current
+** value.  For these latter parameters nothing is written into *pCurrent.)^
+**
+** ^The sqlite3_status() and sqlite3_status64() routines return
+** SQLITE_OK on success and a non-zero [error code] on failure.
+**
+** If either the current value or the highwater mark is too large to
+** be represented by a 32-bit integer, then the values returned by
+** sqlite3_status() are undefined.
+**
+** See also: [sqlite3_db_status()]
+*/
+SQLITE_API int sqlite3_status(int op, int *pCurrent, int *pHighwater, int resetFlag);
+SQLITE_API int sqlite3_status64(
+  int op,
+  sqlite3_int64 *pCurrent,
+  sqlite3_int64 *pHighwater,
+  int resetFlag
+);
+
+
+/*
+** CAPI3REF: Status Parameters
+** KEYWORDS: {status parameters}
+**
+** These integer constants designate various run-time status parameters
+** that can be returned by [sqlite3_status()].
+**
+** <dl>
+** [[SQLITE_STATUS_MEMORY_USED]] ^(<dt>SQLITE_STATUS_MEMORY_USED</dt>
+** <dd>This parameter is the current amount of memory checked out
+** using [sqlite3_malloc()], either directly or indirectly.  The
+** figure includes calls made to [sqlite3_malloc()] by the application
+** and internal memory usage by the SQLite library.  Scratch memory
+** controlled by [SQLITE_CONFIG_SCRATCH] and auxiliary page-cache
+** memory controlled by [SQLITE_CONFIG_PAGECACHE] is not included in
+** this parameter.  The amount returned is the sum of the allocation
+** sizes as reported by the xSize method in [sqlite3_mem_methods].</dd>)^
+**
+** [[SQLITE_STATUS_MALLOC_SIZE]] ^(<dt>SQLITE_STATUS_MALLOC_SIZE</dt>
+** <dd>This parameter records the largest memory allocation request
+** handed to [sqlite3_malloc()] or [sqlite3_realloc()] (or their
+** internal equivalents).  Only the value returned in the
+** *pHighwater parameter to [sqlite3_status()] is of interest.  
+** The value written into the *pCurrent parameter is undefined.</dd>)^
+**
+** [[SQLITE_STATUS_MALLOC_COUNT]] ^(<dt>SQLITE_STATUS_MALLOC_COUNT</dt>
+** <dd>This parameter records the number of separate memory allocations
+** currently checked out.</dd>)^
+**
+** [[SQLITE_STATUS_PAGECACHE_USED]] ^(<dt>SQLITE_STATUS_PAGECACHE_USED</dt>
+** <dd>This parameter returns the number of pages used out of the
+** [pagecache memory allocator] that was configured using 
+** [SQLITE_CONFIG_PAGECACHE].  The
+** value returned is in pages, not in bytes.</dd>)^
+**
+** [[SQLITE_STATUS_PAGECACHE_OVERFLOW]] 
+** ^(<dt>SQLITE_STATUS_PAGECACHE_OVERFLOW</dt>
+** <dd>This parameter returns the number of bytes of page cache
+** allocation which could not be satisfied by the [SQLITE_CONFIG_PAGECACHE]
+** buffer and where forced to overflow to [sqlite3_malloc()].  The
+** returned value includes allocations that overflowed because they
+** where too large (they were larger than the "sz" parameter to
+** [SQLITE_CONFIG_PAGECACHE]) and allocations that overflowed because
+** no space was left in the page cache.</dd>)^
+**
+** [[SQLITE_STATUS_PAGECACHE_SIZE]] ^(<dt>SQLITE_STATUS_PAGECACHE_SIZE</dt>
+** <dd>This parameter records the largest memory allocation request
+** handed to [pagecache memory allocator].  Only the value returned in the
+** *pHighwater parameter to [sqlite3_status()] is of interest.  
+** The value written into the *pCurrent parameter is undefined.</dd>)^
+**
+** [[SQLITE_STATUS_SCRATCH_USED]] ^(<dt>SQLITE_STATUS_SCRATCH_USED</dt>
+** <dd>This parameter returns the number of allocations used out of the
+** [scratch memory allocator] configured using
+** [SQLITE_CONFIG_SCRATCH].  The value returned is in allocations, not
+** in bytes.  Since a single thread may only have one scratch allocation
+** outstanding at time, this parameter also reports the number of threads
+** using scratch memory at the same time.</dd>)^
+**
+** [[SQLITE_STATUS_SCRATCH_OVERFLOW]] ^(<dt>SQLITE_STATUS_SCRATCH_OVERFLOW</dt>
+** <dd>This parameter returns the number of bytes of scratch memory
+** allocation which could not be satisfied by the [SQLITE_CONFIG_SCRATCH]
+** buffer and where forced to overflow to [sqlite3_malloc()].  The values
+** returned include overflows because the requested allocation was too
+** larger (that is, because the requested allocation was larger than the
+** "sz" parameter to [SQLITE_CONFIG_SCRATCH]) and because no scratch buffer
+** slots were available.
+** </dd>)^
+**
+** [[SQLITE_STATUS_SCRATCH_SIZE]] ^(<dt>SQLITE_STATUS_SCRATCH_SIZE</dt>
+** <dd>This parameter records the largest memory allocation request
+** handed to [scratch memory allocator].  Only the value returned in the
+** *pHighwater parameter to [sqlite3_status()] is of interest.  
+** The value written into the *pCurrent parameter is undefined.</dd>)^
+**
+** [[SQLITE_STATUS_PARSER_STACK]] ^(<dt>SQLITE_STATUS_PARSER_STACK</dt>
+** <dd>The *pHighwater parameter records the deepest parser stack. 
+** The *pCurrent value is undefined.  The *pHighwater value is only
+** meaningful if SQLite is compiled with [YYTRACKMAXSTACKDEPTH].</dd>)^
+** </dl>
+**
+** New status parameters may be added from time to time.
+*/
+#define SQLITE_STATUS_MEMORY_USED          0
+#define SQLITE_STATUS_PAGECACHE_USED       1
+#define SQLITE_STATUS_PAGECACHE_OVERFLOW   2
+#define SQLITE_STATUS_SCRATCH_USED         3
+#define SQLITE_STATUS_SCRATCH_OVERFLOW     4
+#define SQLITE_STATUS_MALLOC_SIZE          5
+#define SQLITE_STATUS_PARSER_STACK         6
+#define SQLITE_STATUS_PAGECACHE_SIZE       7
+#define SQLITE_STATUS_SCRATCH_SIZE         8
+#define SQLITE_STATUS_MALLOC_COUNT         9
+
+/*
+** CAPI3REF: Database Connection Status
+** METHOD: sqlite3
+**
+** ^This interface is used to retrieve runtime status information 
+** about a single [database connection].  ^The first argument is the
+** database connection object to be interrogated.  ^The second argument
+** is an integer constant, taken from the set of
+** [SQLITE_DBSTATUS options], that
+** determines the parameter to interrogate.  The set of 
+** [SQLITE_DBSTATUS options] is likely
+** to grow in future releases of SQLite.
+**
+** ^The current value of the requested parameter is written into *pCur
+** and the highest instantaneous value is written into *pHiwtr.  ^If
+** the resetFlg is true, then the highest instantaneous value is
+** reset back down to the current value.
+**
+** ^The sqlite3_db_status() routine returns SQLITE_OK on success and a
+** non-zero [error code] on failure.
+**
+** See also: [sqlite3_status()] and [sqlite3_stmt_status()].
+*/
+SQLITE_API int sqlite3_db_status(sqlite3*, int op, int *pCur, int *pHiwtr, int resetFlg);
+
+/*
+** CAPI3REF: Status Parameters for database connections
+** KEYWORDS: {SQLITE_DBSTATUS options}
+**
+** These constants are the available integer "verbs" that can be passed as
+** the second argument to the [sqlite3_db_status()] interface.
+**
+** New verbs may be added in future releases of SQLite. Existing verbs
+** might be discontinued. Applications should check the return code from
+** [sqlite3_db_status()] to make sure that the call worked.
+** The [sqlite3_db_status()] interface will return a non-zero error code
+** if a discontinued or unsupported verb is invoked.
+**
+** <dl>
+** [[SQLITE_DBSTATUS_LOOKASIDE_USED]] ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_USED</dt>
+** <dd>This parameter returns the number of lookaside memory slots currently
+** checked out.</dd>)^
+**
+** [[SQLITE_DBSTATUS_LOOKASIDE_HIT]] ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_HIT</dt>
+** <dd>This parameter returns the number malloc attempts that were 
+** satisfied using lookaside memory. Only the high-water value is meaningful;
+** the current value is always zero.)^
+**
+** [[SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE]]
+** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE</dt>
+** <dd>This parameter returns the number malloc attempts that might have
+** been satisfied using lookaside memory but failed due to the amount of
+** memory requested being larger than the lookaside slot size.
+** Only the high-water value is meaningful;
+** the current value is always zero.)^
+**
+** [[SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL]]
+** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL</dt>
+** <dd>This parameter returns the number malloc attempts that might have
+** been satisfied using lookaside memory but failed due to all lookaside
+** memory already being in use.
+** Only the high-water value is meaningful;
+** the current value is always zero.)^
+**
+** [[SQLITE_DBSTATUS_CACHE_USED]] ^(<dt>SQLITE_DBSTATUS_CACHE_USED</dt>
+** <dd>This parameter returns the approximate number of bytes of heap
+** memory used by all pager caches associated with the database connection.)^
+** ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_USED is always 0.
+**
+** [[SQLITE_DBSTATUS_CACHE_USED_SHARED]] 
+** ^(<dt>SQLITE_DBSTATUS_CACHE_USED_SHARED</dt>
+** <dd>This parameter is similar to DBSTATUS_CACHE_USED, except that if a
+** pager cache is shared between two or more connections the bytes of heap
+** memory used by that pager cache is divided evenly between the attached
+** connections.)^  In other words, if none of the pager caches associated
+** with the database connection are shared, this request returns the same
+** value as DBSTATUS_CACHE_USED. Or, if one or more or the pager caches are
+** shared, the value returned by this call will be smaller than that returned
+** by DBSTATUS_CACHE_USED. ^The highwater mark associated with
+** SQLITE_DBSTATUS_CACHE_USED_SHARED is always 0.
+**
+** [[SQLITE_DBSTATUS_SCHEMA_USED]] ^(<dt>SQLITE_DBSTATUS_SCHEMA_USED</dt>
+** <dd>This parameter returns the approximate number of bytes of heap
+** memory used to store the schema for all databases associated
+** with the connection - main, temp, and any [ATTACH]-ed databases.)^ 
+** ^The full amount of memory used by the schemas is reported, even if the
+** schema memory is shared with other database connections due to
+** [shared cache mode] being enabled.
+** ^The highwater mark associated with SQLITE_DBSTATUS_SCHEMA_USED is always 0.
+**
+** [[SQLITE_DBSTATUS_STMT_USED]] ^(<dt>SQLITE_DBSTATUS_STMT_USED</dt>
+** <dd>This parameter returns the approximate number of bytes of heap
+** and lookaside memory used by all prepared statements associated with
+** the database connection.)^
+** ^The highwater mark associated with SQLITE_DBSTATUS_STMT_USED is always 0.
+** </dd>
+**
+** [[SQLITE_DBSTATUS_CACHE_HIT]] ^(<dt>SQLITE_DBSTATUS_CACHE_HIT</dt>
+** <dd>This parameter returns the number of pager cache hits that have
+** occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_HIT 
+** is always 0.
+** </dd>
+**
+** [[SQLITE_DBSTATUS_CACHE_MISS]] ^(<dt>SQLITE_DBSTATUS_CACHE_MISS</dt>
+** <dd>This parameter returns the number of pager cache misses that have
+** occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_MISS 
+** is always 0.
+** </dd>
+**
+** [[SQLITE_DBSTATUS_CACHE_WRITE]] ^(<dt>SQLITE_DBSTATUS_CACHE_WRITE</dt>
+** <dd>This parameter returns the number of dirty cache entries that have
+** been written to disk. Specifically, the number of pages written to the
+** wal file in wal mode databases, or the number of pages written to the
+** database file in rollback mode databases. Any pages written as part of
+** transaction rollback or database recovery operations are not included.
+** If an IO or other error occurs while writing a page to disk, the effect
+** on subsequent SQLITE_DBSTATUS_CACHE_WRITE requests is undefined.)^ ^The
+** highwater mark associated with SQLITE_DBSTATUS_CACHE_WRITE is always 0.
+** </dd>
+**
+** [[SQLITE_DBSTATUS_DEFERRED_FKS]] ^(<dt>SQLITE_DBSTATUS_DEFERRED_FKS</dt>
+** <dd>This parameter returns zero for the current value if and only if
+** all foreign key constraints (deferred or immediate) have been
+** resolved.)^  ^The highwater mark is always 0.
+** </dd>
+** </dl>
+*/
+#define SQLITE_DBSTATUS_LOOKASIDE_USED       0
+#define SQLITE_DBSTATUS_CACHE_USED           1
+#define SQLITE_DBSTATUS_SCHEMA_USED          2
+#define SQLITE_DBSTATUS_STMT_USED            3
+#define SQLITE_DBSTATUS_LOOKASIDE_HIT        4
+#define SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE  5
+#define SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL  6
+#define SQLITE_DBSTATUS_CACHE_HIT            7
+#define SQLITE_DBSTATUS_CACHE_MISS           8
+#define SQLITE_DBSTATUS_CACHE_WRITE          9
+#define SQLITE_DBSTATUS_DEFERRED_FKS        10
+#define SQLITE_DBSTATUS_CACHE_USED_SHARED   11
+#define SQLITE_DBSTATUS_MAX                 11   /* Largest defined DBSTATUS */
+
+
+/*
+** CAPI3REF: Prepared Statement Status
+** METHOD: sqlite3_stmt
+**
+** ^(Each prepared statement maintains various
+** [SQLITE_STMTSTATUS counters] that measure the number
+** of times it has performed specific operations.)^  These counters can
+** be used to monitor the performance characteristics of the prepared
+** statements.  For example, if the number of table steps greatly exceeds
+** the number of table searches or result rows, that would tend to indicate
+** that the prepared statement is using a full table scan rather than
+** an index.  
+**
+** ^(This interface is used to retrieve and reset counter values from
+** a [prepared statement].  The first argument is the prepared statement
+** object to be interrogated.  The second argument
+** is an integer code for a specific [SQLITE_STMTSTATUS counter]
+** to be interrogated.)^
+** ^The current value of the requested counter is returned.
+** ^If the resetFlg is true, then the counter is reset to zero after this
+** interface call returns.
+**
+** See also: [sqlite3_status()] and [sqlite3_db_status()].
+*/
+SQLITE_API int sqlite3_stmt_status(sqlite3_stmt*, int op,int resetFlg);
+
+/*
+** CAPI3REF: Status Parameters for prepared statements
+** KEYWORDS: {SQLITE_STMTSTATUS counter} {SQLITE_STMTSTATUS counters}
+**
+** These preprocessor macros define integer codes that name counter
+** values associated with the [sqlite3_stmt_status()] interface.
+** The meanings of the various counters are as follows:
+**
+** <dl>
+** [[SQLITE_STMTSTATUS_FULLSCAN_STEP]] <dt>SQLITE_STMTSTATUS_FULLSCAN_STEP</dt>
+** <dd>^This is the number of times that SQLite has stepped forward in
+** a table as part of a full table scan.  Large numbers for this counter
+** may indicate opportunities for performance improvement through 
+** careful use of indices.</dd>
+**
+** [[SQLITE_STMTSTATUS_SORT]] <dt>SQLITE_STMTSTATUS_SORT</dt>
+** <dd>^This is the number of sort operations that have occurred.
+** A non-zero value in this counter may indicate an opportunity to
+** improvement performance through careful use of indices.</dd>
+**
+** [[SQLITE_STMTSTATUS_AUTOINDEX]] <dt>SQLITE_STMTSTATUS_AUTOINDEX</dt>
+** <dd>^This is the number of rows inserted into transient indices that
+** were created automatically in order to help joins run faster.
+** A non-zero value in this counter may indicate an opportunity to
+** improvement performance by adding permanent indices that do not
+** need to be reinitialized each time the statement is run.</dd>
+**
+** [[SQLITE_STMTSTATUS_VM_STEP]] <dt>SQLITE_STMTSTATUS_VM_STEP</dt>
+** <dd>^This is the number of virtual machine operations executed
+** by the prepared statement if that number is less than or equal
+** to 2147483647.  The number of virtual machine operations can be 
+** used as a proxy for the total work done by the prepared statement.
+** If the number of virtual machine operations exceeds 2147483647
+** then the value returned by this statement status code is undefined.
+** </dd>
+** </dl>
+*/
+#define SQLITE_STMTSTATUS_FULLSCAN_STEP     1
+#define SQLITE_STMTSTATUS_SORT              2
+#define SQLITE_STMTSTATUS_AUTOINDEX         3
+#define SQLITE_STMTSTATUS_VM_STEP           4
+
+/*
+** CAPI3REF: Custom Page Cache Object
+**
+** The sqlite3_pcache type is opaque.  It is implemented by
+** the pluggable module.  The SQLite core has no knowledge of
+** its size or internal structure and never deals with the
+** sqlite3_pcache object except by holding and passing pointers
+** to the object.
+**
+** See [sqlite3_pcache_methods2] for additional information.
+*/
+typedef struct sqlite3_pcache sqlite3_pcache;
+
+/*
+** CAPI3REF: Custom Page Cache Object
+**
+** The sqlite3_pcache_page object represents a single page in the
+** page cache.  The page cache will allocate instances of this
+** object.  Various methods of the page cache use pointers to instances
+** of this object as parameters or as their return value.
+**
+** See [sqlite3_pcache_methods2] for additional information.
+*/
+typedef struct sqlite3_pcache_page sqlite3_pcache_page;
+struct sqlite3_pcache_page {
+  void *pBuf;        /* The content of the page */
+  void *pExtra;      /* Extra information associated with the page */
+};
+
+/*
+** CAPI3REF: Application Defined Page Cache.
+** KEYWORDS: {page cache}
+**
+** ^(The [sqlite3_config]([SQLITE_CONFIG_PCACHE2], ...) interface can
+** register an alternative page cache implementation by passing in an 
+** instance of the sqlite3_pcache_methods2 structure.)^
+** In many applications, most of the heap memory allocated by 
+** SQLite is used for the page cache.
+** By implementing a 
+** custom page cache using this API, an application can better control
+** the amount of memory consumed by SQLite, the way in which 
+** that memory is allocated and released, and the policies used to 
+** determine exactly which parts of a database file are cached and for 
+** how long.
+**
+** The alternative page cache mechanism is an
+** extreme measure that is only needed by the most demanding applications.
+** The built-in page cache is recommended for most uses.
+**
+** ^(The contents of the sqlite3_pcache_methods2 structure are copied to an
+** internal buffer by SQLite within the call to [sqlite3_config].  Hence
+** the application may discard the parameter after the call to
+** [sqlite3_config()] returns.)^
+**
+** [[the xInit() page cache method]]
+** ^(The xInit() method is called once for each effective 
+** call to [sqlite3_initialize()])^
+** (usually only once during the lifetime of the process). ^(The xInit()
+** method is passed a copy of the sqlite3_pcache_methods2.pArg value.)^
+** The intent of the xInit() method is to set up global data structures 
+** required by the custom page cache implementation. 
+** ^(If the xInit() method is NULL, then the 
+** built-in default page cache is used instead of the application defined
+** page cache.)^
+**
+** [[the xShutdown() page cache method]]
+** ^The xShutdown() method is called by [sqlite3_shutdown()].
+** It can be used to clean up 
+** any outstanding resources before process shutdown, if required.
+** ^The xShutdown() method may be NULL.
+**
+** ^SQLite automatically serializes calls to the xInit method,
+** so the xInit method need not be threadsafe.  ^The
+** xShutdown method is only called from [sqlite3_shutdown()] so it does
+** not need to be threadsafe either.  All other methods must be threadsafe
+** in multithreaded applications.
+**
+** ^SQLite will never invoke xInit() more than once without an intervening
+** call to xShutdown().
+**
+** [[the xCreate() page cache methods]]
+** ^SQLite invokes the xCreate() method to construct a new cache instance.
+** SQLite will typically create one cache instance for each open database file,
+** though this is not guaranteed. ^The
+** first parameter, szPage, is the size in bytes of the pages that must
+** be allocated by the cache.  ^szPage will always a power of two.  ^The
+** second parameter szExtra is a number of bytes of extra storage 
+** associated with each page cache entry.  ^The szExtra parameter will
+** a number less than 250.  SQLite will use the
+** extra szExtra bytes on each page to store metadata about the underlying
+** database page on disk.  The value passed into szExtra depends
+** on the SQLite version, the target platform, and how SQLite was compiled.
+** ^The third argument to xCreate(), bPurgeable, is true if the cache being
+** created will be used to cache database pages of a file stored on disk, or
+** false if it is used for an in-memory database. The cache implementation
+** does not have to do anything special based with the value of bPurgeable;
+** it is purely advisory.  ^On a cache where bPurgeable is false, SQLite will
+** never invoke xUnpin() except to deliberately delete a page.
+** ^In other words, calls to xUnpin() on a cache with bPurgeable set to
+** false will always have the "discard" flag set to true.  
+** ^Hence, a cache created with bPurgeable false will
+** never contain any unpinned pages.
+**
+** [[the xCachesize() page cache method]]
+** ^(The xCachesize() method may be called at any time by SQLite to set the
+** suggested maximum cache-size (number of pages stored by) the cache
+** instance passed as the first argument. This is the value configured using
+** the SQLite "[PRAGMA cache_size]" command.)^  As with the bPurgeable
+** parameter, the implementation is not required to do anything with this
+** value; it is advisory only.
+**
+** [[the xPagecount() page cache methods]]
+** The xPagecount() method must return the number of pages currently
+** stored in the cache, both pinned and unpinned.
+** 
+** [[the xFetch() page cache methods]]
+** The xFetch() method locates a page in the cache and returns a pointer to 
+** an sqlite3_pcache_page object associated with that page, or a NULL pointer.
+** The pBuf element of the returned sqlite3_pcache_page object will be a
+** pointer to a buffer of szPage bytes used to store the content of a 
+** single database page.  The pExtra element of sqlite3_pcache_page will be
+** a pointer to the szExtra bytes of extra storage that SQLite has requested
+** for each entry in the page cache.
+**
+** The page to be fetched is determined by the key. ^The minimum key value
+** is 1.  After it has been retrieved using xFetch, the page is considered
+** to be "pinned".
+**
+** If the requested page is already in the page cache, then the page cache
+** implementation must return a pointer to the page buffer with its content
+** intact.  If the requested page is not already in the cache, then the
+** cache implementation should use the value of the createFlag
+** parameter to help it determined what action to take:
+**
+** <table border=1 width=85% align=center>
+** <tr><th> createFlag <th> Behavior when page is not already in cache
+** <tr><td> 0 <td> Do not allocate a new page.  Return NULL.
+** <tr><td> 1 <td> Allocate a new page if it easy and convenient to do so.
+**                 Otherwise return NULL.
+** <tr><td> 2 <td> Make every effort to allocate a new page.  Only return
+**                 NULL if allocating a new page is effectively impossible.
+** </table>
+**
+** ^(SQLite will normally invoke xFetch() with a createFlag of 0 or 1.  SQLite
+** will only use a createFlag of 2 after a prior call with a createFlag of 1
+** failed.)^  In between the to xFetch() calls, SQLite may
+** attempt to unpin one or more cache pages by spilling the content of
+** pinned pages to disk and synching the operating system disk cache.
+**
+** [[the xUnpin() page cache method]]
+** ^xUnpin() is called by SQLite with a pointer to a currently pinned page
+** as its second argument.  If the third parameter, discard, is non-zero,
+** then the page must be evicted from the cache.
+** ^If the discard parameter is
+** zero, then the page may be discarded or retained at the discretion of
+** page cache implementation. ^The page cache implementation
+** may choose to evict unpinned pages at any time.
+**
+** The cache must not perform any reference counting. A single 
+** call to xUnpin() unpins the page regardless of the number of prior calls 
+** to xFetch().
+**
+** [[the xRekey() page cache methods]]
+** The xRekey() method is used to change the key value associated with the
+** page passed as the second argument. If the cache
+** previously contains an entry associated with newKey, it must be
+** discarded. ^Any prior cache entry associated with newKey is guaranteed not
+** to be pinned.
+**
+** When SQLite calls the xTruncate() method, the cache must discard all
+** existing cache entries with page numbers (keys) greater than or equal
+** to the value of the iLimit parameter passed to xTruncate(). If any
+** of these pages are pinned, they are implicitly unpinned, meaning that
+** they can be safely discarded.
+**
+** [[the xDestroy() page cache method]]
+** ^The xDestroy() method is used to delete a cache allocated by xCreate().
+** All resources associated with the specified cache should be freed. ^After
+** calling the xDestroy() method, SQLite considers the [sqlite3_pcache*]
+** handle invalid, and will not use it with any other sqlite3_pcache_methods2
+** functions.
+**
+** [[the xShrink() page cache method]]
+** ^SQLite invokes the xShrink() method when it wants the page cache to
+** free up as much of heap memory as possible.  The page cache implementation
+** is not obligated to free any memory, but well-behaved implementations should
+** do their best.
+*/
+typedef struct sqlite3_pcache_methods2 sqlite3_pcache_methods2;
+struct sqlite3_pcache_methods2 {
+  int iVersion;
+  void *pArg;
+  int (*xInit)(void*);
+  void (*xShutdown)(void*);
+  sqlite3_pcache *(*xCreate)(int szPage, int szExtra, int bPurgeable);
+  void (*xCachesize)(sqlite3_pcache*, int nCachesize);
+  int (*xPagecount)(sqlite3_pcache*);
+  sqlite3_pcache_page *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag);
+  void (*xUnpin)(sqlite3_pcache*, sqlite3_pcache_page*, int discard);
+  void (*xRekey)(sqlite3_pcache*, sqlite3_pcache_page*, 
+      unsigned oldKey, unsigned newKey);
+  void (*xTruncate)(sqlite3_pcache*, unsigned iLimit);
+  void (*xDestroy)(sqlite3_pcache*);
+  void (*xShrink)(sqlite3_pcache*);
+};
+
+/*
+** This is the obsolete pcache_methods object that has now been replaced
+** by sqlite3_pcache_methods2.  This object is not used by SQLite.  It is
+** retained in the header file for backwards compatibility only.
+*/
+typedef struct sqlite3_pcache_methods sqlite3_pcache_methods;
+struct sqlite3_pcache_methods {
+  void *pArg;
+  int (*xInit)(void*);
+  void (*xShutdown)(void*);
+  sqlite3_pcache *(*xCreate)(int szPage, int bPurgeable);
+  void (*xCachesize)(sqlite3_pcache*, int nCachesize);
+  int (*xPagecount)(sqlite3_pcache*);
+  void *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag);
+  void (*xUnpin)(sqlite3_pcache*, void*, int discard);
+  void (*xRekey)(sqlite3_pcache*, void*, unsigned oldKey, unsigned newKey);
+  void (*xTruncate)(sqlite3_pcache*, unsigned iLimit);
+  void (*xDestroy)(sqlite3_pcache*);
+};
+
+
+/*
+** CAPI3REF: Online Backup Object
+**
+** The sqlite3_backup object records state information about an ongoing
+** online backup operation.  ^The sqlite3_backup object is created by
+** a call to [sqlite3_backup_init()] and is destroyed by a call to
+** [sqlite3_backup_finish()].
+**
+** See Also: [Using the SQLite Online Backup API]
+*/
+typedef struct sqlite3_backup sqlite3_backup;
+
+/*
+** CAPI3REF: Online Backup API.
+**
+** The backup API copies the content of one database into another.
+** It is useful either for creating backups of databases or
+** for copying in-memory databases to or from persistent files. 
+**
+** See Also: [Using the SQLite Online Backup API]
+**
+** ^SQLite holds a write transaction open on the destination database file
+** for the duration of the backup operation.
+** ^The source database is read-locked only while it is being read;
+** it is not locked continuously for the entire backup operation.
+** ^Thus, the backup may be performed on a live source database without
+** preventing other database connections from
+** reading or writing to the source database while the backup is underway.
+** 
+** ^(To perform a backup operation: 
+**   <ol>
+**     <li><b>sqlite3_backup_init()</b> is called once to initialize the
+**         backup, 
+**     <li><b>sqlite3_backup_step()</b> is called one or more times to transfer 
+**         the data between the two databases, and finally
+**     <li><b>sqlite3_backup_finish()</b> is called to release all resources 
+**         associated with the backup operation. 
+**   </ol>)^
+** There should be exactly one call to sqlite3_backup_finish() for each
+** successful call to sqlite3_backup_init().
+**
+** [[sqlite3_backup_init()]] <b>sqlite3_backup_init()</b>
+**
+** ^The D and N arguments to sqlite3_backup_init(D,N,S,M) are the 
+** [database connection] associated with the destination database 
+** and the database name, respectively.
+** ^The database name is "main" for the main database, "temp" for the
+** temporary database, or the name specified after the AS keyword in
+** an [ATTACH] statement for an attached database.
+** ^The S and M arguments passed to 
+** sqlite3_backup_init(D,N,S,M) identify the [database connection]
+** and database name of the source database, respectively.
+** ^The source and destination [database connections] (parameters S and D)
+** must be different or else sqlite3_backup_init(D,N,S,M) will fail with
+** an error.
+**
+** ^A call to sqlite3_backup_init() will fail, returning NULL, if 
+** there is already a read or read-write transaction open on the 
+** destination database.
+**
+** ^If an error occurs within sqlite3_backup_init(D,N,S,M), then NULL is
+** returned and an error code and error message are stored in the
+** destination [database connection] D.
+** ^The error code and message for the failed call to sqlite3_backup_init()
+** can be retrieved using the [sqlite3_errcode()], [sqlite3_errmsg()], and/or
+** [sqlite3_errmsg16()] functions.
+** ^A successful call to sqlite3_backup_init() returns a pointer to an
+** [sqlite3_backup] object.
+** ^The [sqlite3_backup] object may be used with the sqlite3_backup_step() and
+** sqlite3_backup_finish() functions to perform the specified backup 
+** operation.
+**
+** [[sqlite3_backup_step()]] <b>sqlite3_backup_step()</b>
+**
+** ^Function sqlite3_backup_step(B,N) will copy up to N pages between 
+** the source and destination databases specified by [sqlite3_backup] object B.
+** ^If N is negative, all remaining source pages are copied. 
+** ^If sqlite3_backup_step(B,N) successfully copies N pages and there
+** are still more pages to be copied, then the function returns [SQLITE_OK].
+** ^If sqlite3_backup_step(B,N) successfully finishes copying all pages
+** from source to destination, then it returns [SQLITE_DONE].
+** ^If an error occurs while running sqlite3_backup_step(B,N),
+** then an [error code] is returned. ^As well as [SQLITE_OK] and
+** [SQLITE_DONE], a call to sqlite3_backup_step() may return [SQLITE_READONLY],
+** [SQLITE_NOMEM], [SQLITE_BUSY], [SQLITE_LOCKED], or an
+** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX] extended error code.
+**
+** ^(The sqlite3_backup_step() might return [SQLITE_READONLY] if
+** <ol>
+** <li> the destination database was opened read-only, or
+** <li> the destination database is using write-ahead-log journaling
+** and the destination and source page sizes differ, or
+** <li> the destination database is an in-memory database and the
+** destination and source page sizes differ.
+** </ol>)^
+**
+** ^If sqlite3_backup_step() cannot obtain a required file-system lock, then
+** the [sqlite3_busy_handler | busy-handler function]
+** is invoked (if one is specified). ^If the 
+** busy-handler returns non-zero before the lock is available, then 
+** [SQLITE_BUSY] is returned to the caller. ^In this case the call to
+** sqlite3_backup_step() can be retried later. ^If the source
+** [database connection]
+** is being used to write to the source database when sqlite3_backup_step()
+** is called, then [SQLITE_LOCKED] is returned immediately. ^Again, in this
+** case the call to sqlite3_backup_step() can be retried later on. ^(If
+** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX], [SQLITE_NOMEM], or
+** [SQLITE_READONLY] is returned, then 
+** there is no point in retrying the call to sqlite3_backup_step(). These 
+** errors are considered fatal.)^  The application must accept 
+** that the backup operation has failed and pass the backup operation handle 
+** to the sqlite3_backup_finish() to release associated resources.
+**
+** ^The first call to sqlite3_backup_step() obtains an exclusive lock
+** on the destination file. ^The exclusive lock is not released until either 
+** sqlite3_backup_finish() is called or the backup operation is complete 
+** and sqlite3_backup_step() returns [SQLITE_DONE].  ^Every call to
+** sqlite3_backup_step() obtains a [shared lock] on the source database that
+** lasts for the duration of the sqlite3_backup_step() call.
+** ^Because the source database is not locked between calls to
+** sqlite3_backup_step(), the source database may be modified mid-way
+** through the backup process.  ^If the source database is modified by an
+** external process or via a database connection other than the one being
+** used by the backup operation, then the backup will be automatically
+** restarted by the next call to sqlite3_backup_step(). ^If the source 
+** database is modified by the using the same database connection as is used
+** by the backup operation, then the backup database is automatically
+** updated at the same time.
+**
+** [[sqlite3_backup_finish()]] <b>sqlite3_backup_finish()</b>
+**
+** When sqlite3_backup_step() has returned [SQLITE_DONE], or when the 
+** application wishes to abandon the backup operation, the application
+** should destroy the [sqlite3_backup] by passing it to sqlite3_backup_finish().
+** ^The sqlite3_backup_finish() interfaces releases all
+** resources associated with the [sqlite3_backup] object. 
+** ^If sqlite3_backup_step() has not yet returned [SQLITE_DONE], then any
+** active write-transaction on the destination database is rolled back.
+** The [sqlite3_backup] object is invalid
+** and may not be used following a call to sqlite3_backup_finish().
+**
+** ^The value returned by sqlite3_backup_finish is [SQLITE_OK] if no
+** sqlite3_backup_step() errors occurred, regardless or whether or not
+** sqlite3_backup_step() completed.
+** ^If an out-of-memory condition or IO error occurred during any prior
+** sqlite3_backup_step() call on the same [sqlite3_backup] object, then
+** sqlite3_backup_finish() returns the corresponding [error code].
+**
+** ^A return of [SQLITE_BUSY] or [SQLITE_LOCKED] from sqlite3_backup_step()
+** is not a permanent error and does not affect the return value of
+** sqlite3_backup_finish().
+**
+** [[sqlite3_backup_remaining()]] [[sqlite3_backup_pagecount()]]
+** <b>sqlite3_backup_remaining() and sqlite3_backup_pagecount()</b>
+**
+** ^The sqlite3_backup_remaining() routine returns the number of pages still
+** to be backed up at the conclusion of the most recent sqlite3_backup_step().
+** ^The sqlite3_backup_pagecount() routine returns the total number of pages
+** in the source database at the conclusion of the most recent
+** sqlite3_backup_step().
+** ^(The values returned by these functions are only updated by
+** sqlite3_backup_step(). If the source database is modified in a way that
+** changes the size of the source database or the number of pages remaining,
+** those changes are not reflected in the output of sqlite3_backup_pagecount()
+** and sqlite3_backup_remaining() until after the next
+** sqlite3_backup_step().)^
+**
+** <b>Concurrent Usage of Database Handles</b>
+**
+** ^The source [database connection] may be used by the application for other
+** purposes while a backup operation is underway or being initialized.
+** ^If SQLite is compiled and configured to support threadsafe database
+** connections, then the source database connection may be used concurrently
+** from within other threads.
+**
+** However, the application must guarantee that the destination 
+** [database connection] is not passed to any other API (by any thread) after 
+** sqlite3_backup_init() is called and before the corresponding call to
+** sqlite3_backup_finish().  SQLite does not currently check to see
+** if the application incorrectly accesses the destination [database connection]
+** and so no error code is reported, but the operations may malfunction
+** nevertheless.  Use of the destination database connection while a
+** backup is in progress might also also cause a mutex deadlock.
+**
+** If running in [shared cache mode], the application must
+** guarantee that the shared cache used by the destination database
+** is not accessed while the backup is running. In practice this means
+** that the application must guarantee that the disk file being 
+** backed up to is not accessed by any connection within the process,
+** not just the specific connection that was passed to sqlite3_backup_init().
+**
+** The [sqlite3_backup] object itself is partially threadsafe. Multiple 
+** threads may safely make multiple concurrent calls to sqlite3_backup_step().
+** However, the sqlite3_backup_remaining() and sqlite3_backup_pagecount()
+** APIs are not strictly speaking threadsafe. If they are invoked at the
+** same time as another thread is invoking sqlite3_backup_step() it is
+** possible that they return invalid values.
+*/
+SQLITE_API sqlite3_backup *sqlite3_backup_init(
+  sqlite3 *pDest,                        /* Destination database handle */
+  const char *zDestName,                 /* Destination database name */
+  sqlite3 *pSource,                      /* Source database handle */
+  const char *zSourceName                /* Source database name */
+);
+SQLITE_API int sqlite3_backup_step(sqlite3_backup *p, int nPage);
+SQLITE_API int sqlite3_backup_finish(sqlite3_backup *p);
+SQLITE_API int sqlite3_backup_remaining(sqlite3_backup *p);
+SQLITE_API int sqlite3_backup_pagecount(sqlite3_backup *p);
+
+/*
+** CAPI3REF: Unlock Notification
+** METHOD: sqlite3
+**
+** ^When running in shared-cache mode, a database operation may fail with
+** an [SQLITE_LOCKED] error if the required locks on the shared-cache or
+** individual tables within the shared-cache cannot be obtained. See
+** [SQLite Shared-Cache Mode] for a description of shared-cache locking. 
+** ^This API may be used to register a callback that SQLite will invoke 
+** when the connection currently holding the required lock relinquishes it.
+** ^This API is only available if the library was compiled with the
+** [SQLITE_ENABLE_UNLOCK_NOTIFY] C-preprocessor symbol defined.
+**
+** See Also: [Using the SQLite Unlock Notification Feature].
+**
+** ^Shared-cache locks are released when a database connection concludes
+** its current transaction, either by committing it or rolling it back. 
+**
+** ^When a connection (known as the blocked connection) fails to obtain a
+** shared-cache lock and SQLITE_LOCKED is returned to the caller, the
+** identity of the database connection (the blocking connection) that
+** has locked the required resource is stored internally. ^After an 
+** application receives an SQLITE_LOCKED error, it may call the
+** sqlite3_unlock_notify() method with the blocked connection handle as 
+** the first argument to register for a callback that will be invoked
+** when the blocking connections current transaction is concluded. ^The
+** callback is invoked from within the [sqlite3_step] or [sqlite3_close]
+** call that concludes the blocking connections transaction.
+**
+** ^(If sqlite3_unlock_notify() is called in a multi-threaded application,
+** there is a chance that the blocking connection will have already
+** concluded its transaction by the time sqlite3_unlock_notify() is invoked.
+** If this happens, then the specified callback is invoked immediately,
+** from within the call to sqlite3_unlock_notify().)^
+**
+** ^If the blocked connection is attempting to obtain a write-lock on a
+** shared-cache table, and more than one other connection currently holds
+** a read-lock on the same table, then SQLite arbitrarily selects one of 
+** the other connections to use as the blocking connection.
+**
+** ^(There may be at most one unlock-notify callback registered by a 
+** blocked connection. If sqlite3_unlock_notify() is called when the
+** blocked connection already has a registered unlock-notify callback,
+** then the new callback replaces the old.)^ ^If sqlite3_unlock_notify() is
+** called with a NULL pointer as its second argument, then any existing
+** unlock-notify callback is canceled. ^The blocked connections 
+** unlock-notify callback may also be canceled by closing the blocked
+** connection using [sqlite3_close()].
+**
+** The unlock-notify callback is not reentrant. If an application invokes
+** any sqlite3_xxx API functions from within an unlock-notify callback, a
+** crash or deadlock may be the result.
+**
+** ^Unless deadlock is detected (see below), sqlite3_unlock_notify() always
+** returns SQLITE_OK.
+**
+** <b>Callback Invocation Details</b>
+**
+** When an unlock-notify callback is registered, the application provides a 
+** single void* pointer that is passed to the callback when it is invoked.
+** However, the signature of the callback function allows SQLite to pass
+** it an array of void* context pointers. The first argument passed to
+** an unlock-notify callback is a pointer to an array of void* pointers,
+** and the second is the number of entries in the array.
+**
+** When a blocking connections transaction is concluded, there may be
+** more than one blocked connection that has registered for an unlock-notify
+** callback. ^If two or more such blocked connections have specified the
+** same callback function, then instead of invoking the callback function
+** multiple times, it is invoked once with the set of void* context pointers
+** specified by the blocked connections bundled together into an array.
+** This gives the application an opportunity to prioritize any actions 
+** related to the set of unblocked database connections.
+**
+** <b>Deadlock Detection</b>
+**
+** Assuming that after registering for an unlock-notify callback a 
+** database waits for the callback to be issued before taking any further
+** action (a reasonable assumption), then using this API may cause the
+** application to deadlock. For example, if connection X is waiting for
+** connection Y's transaction to be concluded, and similarly connection
+** Y is waiting on connection X's transaction, then neither connection
+** will proceed and the system may remain deadlocked indefinitely.
+**
+** To avoid this scenario, the sqlite3_unlock_notify() performs deadlock
+** detection. ^If a given call to sqlite3_unlock_notify() would put the
+** system in a deadlocked state, then SQLITE_LOCKED is returned and no
+** unlock-notify callback is registered. The system is said to be in
+** a deadlocked state if connection A has registered for an unlock-notify
+** callback on the conclusion of connection B's transaction, and connection
+** B has itself registered for an unlock-notify callback when connection
+** A's transaction is concluded. ^Indirect deadlock is also detected, so
+** the system is also considered to be deadlocked if connection B has
+** registered for an unlock-notify callback on the conclusion of connection
+** C's transaction, where connection C is waiting on connection A. ^Any
+** number of levels of indirection are allowed.
+**
+** <b>The "DROP TABLE" Exception</b>
+**
+** When a call to [sqlite3_step()] returns SQLITE_LOCKED, it is almost 
+** always appropriate to call sqlite3_unlock_notify(). There is however,
+** one exception. When executing a "DROP TABLE" or "DROP INDEX" statement,
+** SQLite checks if there are any currently executing SELECT statements
+** that belong to the same connection. If there are, SQLITE_LOCKED is
+** returned. In this case there is no "blocking connection", so invoking
+** sqlite3_unlock_notify() results in the unlock-notify callback being
+** invoked immediately. If the application then re-attempts the "DROP TABLE"
+** or "DROP INDEX" query, an infinite loop might be the result.
+**
+** One way around this problem is to check the extended error code returned
+** by an sqlite3_step() call. ^(If there is a blocking connection, then the
+** extended error code is set to SQLITE_LOCKED_SHAREDCACHE. Otherwise, in
+** the special "DROP TABLE/INDEX" case, the extended error code is just 
+** SQLITE_LOCKED.)^
+*/
+SQLITE_API int sqlite3_unlock_notify(
+  sqlite3 *pBlocked,                          /* Waiting connection */
+  void (*xNotify)(void **apArg, int nArg),    /* Callback function to invoke */
+  void *pNotifyArg                            /* Argument to pass to xNotify */
+);
+
+
+/*
+** CAPI3REF: String Comparison
+**
+** ^The [sqlite3_stricmp()] and [sqlite3_strnicmp()] APIs allow applications
+** and extensions to compare the contents of two buffers containing UTF-8
+** strings in a case-independent fashion, using the same definition of "case
+** independence" that SQLite uses internally when comparing identifiers.
+*/
+SQLITE_API int sqlite3_stricmp(const char *, const char *);
+SQLITE_API int sqlite3_strnicmp(const char *, const char *, int);
+
+/*
+** CAPI3REF: String Globbing
+*
+** ^The [sqlite3_strglob(P,X)] interface returns zero if and only if
+** string X matches the [GLOB] pattern P.
+** ^The definition of [GLOB] pattern matching used in
+** [sqlite3_strglob(P,X)] is the same as for the "X GLOB P" operator in the
+** SQL dialect understood by SQLite.  ^The [sqlite3_strglob(P,X)] function
+** is case sensitive.
+**
+** Note that this routine returns zero on a match and non-zero if the strings
+** do not match, the same as [sqlite3_stricmp()] and [sqlite3_strnicmp()].
+**
+** See also: [sqlite3_strlike()].
+*/
+SQLITE_API int sqlite3_strglob(const char *zGlob, const char *zStr);
+
+/*
+** CAPI3REF: String LIKE Matching
+*
+** ^The [sqlite3_strlike(P,X,E)] interface returns zero if and only if
+** string X matches the [LIKE] pattern P with escape character E.
+** ^The definition of [LIKE] pattern matching used in
+** [sqlite3_strlike(P,X,E)] is the same as for the "X LIKE P ESCAPE E"
+** operator in the SQL dialect understood by SQLite.  ^For "X LIKE P" without
+** the ESCAPE clause, set the E parameter of [sqlite3_strlike(P,X,E)] to 0.
+** ^As with the LIKE operator, the [sqlite3_strlike(P,X,E)] function is case
+** insensitive - equivalent upper and lower case ASCII characters match
+** one another.
+**
+** ^The [sqlite3_strlike(P,X,E)] function matches Unicode characters, though
+** only ASCII characters are case folded.
+**
+** Note that this routine returns zero on a match and non-zero if the strings
+** do not match, the same as [sqlite3_stricmp()] and [sqlite3_strnicmp()].
+**
+** See also: [sqlite3_strglob()].
+*/
+SQLITE_API int sqlite3_strlike(const char *zGlob, const char *zStr, unsigned int cEsc);
+
+/*
+** CAPI3REF: Error Logging Interface
+**
+** ^The [sqlite3_log()] interface writes a message into the [error log]
+** established by the [SQLITE_CONFIG_LOG] option to [sqlite3_config()].
+** ^If logging is enabled, the zFormat string and subsequent arguments are
+** used with [sqlite3_snprintf()] to generate the final output string.
+**
+** The sqlite3_log() interface is intended for use by extensions such as
+** virtual tables, collating functions, and SQL functions.  While there is
+** nothing to prevent an application from calling sqlite3_log(), doing so
+** is considered bad form.
+**
+** The zFormat string must not be NULL.
+**
+** To avoid deadlocks and other threading problems, the sqlite3_log() routine
+** will not use dynamically allocated memory.  The log message is stored in
+** a fixed-length buffer on the stack.  If the log message is longer than
+** a few hundred characters, it will be truncated to the length of the
+** buffer.
+*/
+SQLITE_API void sqlite3_log(int iErrCode, const char *zFormat, ...);
+
+/*
+** CAPI3REF: Write-Ahead Log Commit Hook
+** METHOD: sqlite3
+**
+** ^The [sqlite3_wal_hook()] function is used to register a callback that
+** is invoked each time data is committed to a database in wal mode.
+**
+** ^(The callback is invoked by SQLite after the commit has taken place and 
+** the associated write-lock on the database released)^, so the implementation 
+** may read, write or [checkpoint] the database as required.
+**
+** ^The first parameter passed to the callback function when it is invoked
+** is a copy of the third parameter passed to sqlite3_wal_hook() when
+** registering the callback. ^The second is a copy of the database handle.
+** ^The third parameter is the name of the database that was written to -
+** either "main" or the name of an [ATTACH]-ed database. ^The fourth parameter
+** is the number of pages currently in the write-ahead log file,
+** including those that were just committed.
+**
+** The callback function should normally return [SQLITE_OK].  ^If an error
+** code is returned, that error will propagate back up through the
+** SQLite code base to cause the statement that provoked the callback
+** to report an error, though the commit will have still occurred. If the
+** callback returns [SQLITE_ROW] or [SQLITE_DONE], or if it returns a value
+** that does not correspond to any valid SQLite error code, the results
+** are undefined.
+**
+** A single database handle may have at most a single write-ahead log callback 
+** registered at one time. ^Calling [sqlite3_wal_hook()] replaces any
+** previously registered write-ahead log callback. ^Note that the
+** [sqlite3_wal_autocheckpoint()] interface and the
+** [wal_autocheckpoint pragma] both invoke [sqlite3_wal_hook()] and will
+** overwrite any prior [sqlite3_wal_hook()] settings.
+*/
+SQLITE_API void *sqlite3_wal_hook(
+  sqlite3*, 
+  int(*)(void *,sqlite3*,const char*,int),
+  void*
+);
+
+/*
+** CAPI3REF: Configure an auto-checkpoint
+** METHOD: sqlite3
+**
+** ^The [sqlite3_wal_autocheckpoint(D,N)] is a wrapper around
+** [sqlite3_wal_hook()] that causes any database on [database connection] D
+** to automatically [checkpoint]
+** after committing a transaction if there are N or
+** more frames in the [write-ahead log] file.  ^Passing zero or 
+** a negative value as the nFrame parameter disables automatic
+** checkpoints entirely.
+**
+** ^The callback registered by this function replaces any existing callback
+** registered using [sqlite3_wal_hook()].  ^Likewise, registering a callback
+** using [sqlite3_wal_hook()] disables the automatic checkpoint mechanism
+** configured by this function.
+**
+** ^The [wal_autocheckpoint pragma] can be used to invoke this interface
+** from SQL.
+**
+** ^Checkpoints initiated by this mechanism are
+** [sqlite3_wal_checkpoint_v2|PASSIVE].
+**
+** ^Every new [database connection] defaults to having the auto-checkpoint
+** enabled with a threshold of 1000 or [SQLITE_DEFAULT_WAL_AUTOCHECKPOINT]
+** pages.  The use of this interface
+** is only necessary if the default setting is found to be suboptimal
+** for a particular application.
+*/
+SQLITE_API int sqlite3_wal_autocheckpoint(sqlite3 *db, int N);
+
+/*
+** CAPI3REF: Checkpoint a database
+** METHOD: sqlite3
+**
+** ^(The sqlite3_wal_checkpoint(D,X) is equivalent to
+** [sqlite3_wal_checkpoint_v2](D,X,[SQLITE_CHECKPOINT_PASSIVE],0,0).)^
+**
+** In brief, sqlite3_wal_checkpoint(D,X) causes the content in the 
+** [write-ahead log] for database X on [database connection] D to be
+** transferred into the database file and for the write-ahead log to
+** be reset.  See the [checkpointing] documentation for addition
+** information.
+**
+** This interface used to be the only way to cause a checkpoint to
+** occur.  But then the newer and more powerful [sqlite3_wal_checkpoint_v2()]
+** interface was added.  This interface is retained for backwards
+** compatibility and as a convenience for applications that need to manually
+** start a callback but which do not need the full power (and corresponding
+** complication) of [sqlite3_wal_checkpoint_v2()].
+*/
+SQLITE_API int sqlite3_wal_checkpoint(sqlite3 *db, const char *zDb);
+
+/*
+** CAPI3REF: Checkpoint a database
+** METHOD: sqlite3
+**
+** ^(The sqlite3_wal_checkpoint_v2(D,X,M,L,C) interface runs a checkpoint
+** operation on database X of [database connection] D in mode M.  Status
+** information is written back into integers pointed to by L and C.)^
+** ^(The M parameter must be a valid [checkpoint mode]:)^
+**
+** <dl>
+** <dt>SQLITE_CHECKPOINT_PASSIVE<dd>
+**   ^Checkpoint as many frames as possible without waiting for any database 
+**   readers or writers to finish, then sync the database file if all frames 
+**   in the log were checkpointed. ^The [busy-handler callback]
+**   is never invoked in the SQLITE_CHECKPOINT_PASSIVE mode.  
+**   ^On the other hand, passive mode might leave the checkpoint unfinished
+**   if there are concurrent readers or writers.
+**
+** <dt>SQLITE_CHECKPOINT_FULL<dd>
+**   ^This mode blocks (it invokes the
+**   [sqlite3_busy_handler|busy-handler callback]) until there is no
+**   database writer and all readers are reading from the most recent database
+**   snapshot. ^It then checkpoints all frames in the log file and syncs the
+**   database file. ^This mode blocks new database writers while it is pending,
+**   but new database readers are allowed to continue unimpeded.
+**
+** <dt>SQLITE_CHECKPOINT_RESTART<dd>
+**   ^This mode works the same way as SQLITE_CHECKPOINT_FULL with the addition
+**   that after checkpointing the log file it blocks (calls the 
+**   [busy-handler callback])
+**   until all readers are reading from the database file only. ^This ensures 
+**   that the next writer will restart the log file from the beginning.
+**   ^Like SQLITE_CHECKPOINT_FULL, this mode blocks new
+**   database writer attempts while it is pending, but does not impede readers.
+**
+** <dt>SQLITE_CHECKPOINT_TRUNCATE<dd>
+**   ^This mode works the same way as SQLITE_CHECKPOINT_RESTART with the
+**   addition that it also truncates the log file to zero bytes just prior
+**   to a successful return.
+** </dl>
+**
+** ^If pnLog is not NULL, then *pnLog is set to the total number of frames in
+** the log file or to -1 if the checkpoint could not run because
+** of an error or because the database is not in [WAL mode]. ^If pnCkpt is not
+** NULL,then *pnCkpt is set to the total number of checkpointed frames in the
+** log file (including any that were already checkpointed before the function
+** was called) or to -1 if the checkpoint could not run due to an error or
+** because the database is not in WAL mode. ^Note that upon successful
+** completion of an SQLITE_CHECKPOINT_TRUNCATE, the log file will have been
+** truncated to zero bytes and so both *pnLog and *pnCkpt will be set to zero.
+**
+** ^All calls obtain an exclusive "checkpoint" lock on the database file. ^If
+** any other process is running a checkpoint operation at the same time, the 
+** lock cannot be obtained and SQLITE_BUSY is returned. ^Even if there is a 
+** busy-handler configured, it will not be invoked in this case.
+**
+** ^The SQLITE_CHECKPOINT_FULL, RESTART and TRUNCATE modes also obtain the 
+** exclusive "writer" lock on the database file. ^If the writer lock cannot be
+** obtained immediately, and a busy-handler is configured, it is invoked and
+** the writer lock retried until either the busy-handler returns 0 or the lock
+** is successfully obtained. ^The busy-handler is also invoked while waiting for
+** database readers as described above. ^If the busy-handler returns 0 before
+** the writer lock is obtained or while waiting for database readers, the
+** checkpoint operation proceeds from that point in the same way as 
+** SQLITE_CHECKPOINT_PASSIVE - checkpointing as many frames as possible 
+** without blocking any further. ^SQLITE_BUSY is returned in this case.
+**
+** ^If parameter zDb is NULL or points to a zero length string, then the
+** specified operation is attempted on all WAL databases [attached] to 
+** [database connection] db.  In this case the
+** values written to output parameters *pnLog and *pnCkpt are undefined. ^If 
+** an SQLITE_BUSY error is encountered when processing one or more of the 
+** attached WAL databases, the operation is still attempted on any remaining 
+** attached databases and SQLITE_BUSY is returned at the end. ^If any other 
+** error occurs while processing an attached database, processing is abandoned 
+** and the error code is returned to the caller immediately. ^If no error 
+** (SQLITE_BUSY or otherwise) is encountered while processing the attached 
+** databases, SQLITE_OK is returned.
+**
+** ^If database zDb is the name of an attached database that is not in WAL
+** mode, SQLITE_OK is returned and both *pnLog and *pnCkpt set to -1. ^If
+** zDb is not NULL (or a zero length string) and is not the name of any
+** attached database, SQLITE_ERROR is returned to the caller.
+**
+** ^Unless it returns SQLITE_MISUSE,
+** the sqlite3_wal_checkpoint_v2() interface
+** sets the error information that is queried by
+** [sqlite3_errcode()] and [sqlite3_errmsg()].
+**
+** ^The [PRAGMA wal_checkpoint] command can be used to invoke this interface
+** from SQL.
+*/
+SQLITE_API int sqlite3_wal_checkpoint_v2(
+  sqlite3 *db,                    /* Database handle */
+  const char *zDb,                /* Name of attached database (or NULL) */
+  int eMode,                      /* SQLITE_CHECKPOINT_* value */
+  int *pnLog,                     /* OUT: Size of WAL log in frames */
+  int *pnCkpt                     /* OUT: Total number of frames checkpointed */
+);
+
+/*
+** CAPI3REF: Checkpoint Mode Values
+** KEYWORDS: {checkpoint mode}
+**
+** These constants define all valid values for the "checkpoint mode" passed
+** as the third parameter to the [sqlite3_wal_checkpoint_v2()] interface.
+** See the [sqlite3_wal_checkpoint_v2()] documentation for details on the
+** meaning of each of these checkpoint modes.
+*/
+#define SQLITE_CHECKPOINT_PASSIVE  0  /* Do as much as possible w/o blocking */
+#define SQLITE_CHECKPOINT_FULL     1  /* Wait for writers, then checkpoint */
+#define SQLITE_CHECKPOINT_RESTART  2  /* Like FULL but wait for for readers */
+#define SQLITE_CHECKPOINT_TRUNCATE 3  /* Like RESTART but also truncate WAL */
+
+/*
+** CAPI3REF: Virtual Table Interface Configuration
+**
+** This function may be called by either the [xConnect] or [xCreate] method
+** of a [virtual table] implementation to configure
+** various facets of the virtual table interface.
+**
+** If this interface is invoked outside the context of an xConnect or
+** xCreate virtual table method then the behavior is undefined.
+**
+** At present, there is only one option that may be configured using
+** this function. (See [SQLITE_VTAB_CONSTRAINT_SUPPORT].)  Further options
+** may be added in the future.
+*/
+SQLITE_API int sqlite3_vtab_config(sqlite3*, int op, ...);
+
+/*
+** CAPI3REF: Virtual Table Configuration Options
+**
+** These macros define the various options to the
+** [sqlite3_vtab_config()] interface that [virtual table] implementations
+** can use to customize and optimize their behavior.
+**
+** <dl>
+** <dt>SQLITE_VTAB_CONSTRAINT_SUPPORT
+** <dd>Calls of the form
+** [sqlite3_vtab_config](db,SQLITE_VTAB_CONSTRAINT_SUPPORT,X) are supported,
+** where X is an integer.  If X is zero, then the [virtual table] whose
+** [xCreate] or [xConnect] method invoked [sqlite3_vtab_config()] does not
+** support constraints.  In this configuration (which is the default) if
+** a call to the [xUpdate] method returns [SQLITE_CONSTRAINT], then the entire
+** statement is rolled back as if [ON CONFLICT | OR ABORT] had been
+** specified as part of the users SQL statement, regardless of the actual
+** ON CONFLICT mode specified.
+**
+** If X is non-zero, then the virtual table implementation guarantees
+** that if [xUpdate] returns [SQLITE_CONSTRAINT], it will do so before
+** any modifications to internal or persistent data structures have been made.
+** If the [ON CONFLICT] mode is ABORT, FAIL, IGNORE or ROLLBACK, SQLite 
+** is able to roll back a statement or database transaction, and abandon
+** or continue processing the current SQL statement as appropriate. 
+** If the ON CONFLICT mode is REPLACE and the [xUpdate] method returns
+** [SQLITE_CONSTRAINT], SQLite handles this as if the ON CONFLICT mode
+** had been ABORT.
+**
+** Virtual table implementations that are required to handle OR REPLACE
+** must do so within the [xUpdate] method. If a call to the 
+** [sqlite3_vtab_on_conflict()] function indicates that the current ON 
+** CONFLICT policy is REPLACE, the virtual table implementation should 
+** silently replace the appropriate rows within the xUpdate callback and
+** return SQLITE_OK. Or, if this is not possible, it may return
+** SQLITE_CONSTRAINT, in which case SQLite falls back to OR ABORT 
+** constraint handling.
+** </dl>
+*/
+#define SQLITE_VTAB_CONSTRAINT_SUPPORT 1
+
+/*
+** CAPI3REF: Determine The Virtual Table Conflict Policy
+**
+** This function may only be called from within a call to the [xUpdate] method
+** of a [virtual table] implementation for an INSERT or UPDATE operation. ^The
+** value returned is one of [SQLITE_ROLLBACK], [SQLITE_IGNORE], [SQLITE_FAIL],
+** [SQLITE_ABORT], or [SQLITE_REPLACE], according to the [ON CONFLICT] mode
+** of the SQL statement that triggered the call to the [xUpdate] method of the
+** [virtual table].
+*/
+SQLITE_API int sqlite3_vtab_on_conflict(sqlite3 *);
+
+/*
+** CAPI3REF: Conflict resolution modes
+** KEYWORDS: {conflict resolution mode}
+**
+** These constants are returned by [sqlite3_vtab_on_conflict()] to
+** inform a [virtual table] implementation what the [ON CONFLICT] mode
+** is for the SQL statement being evaluated.
+**
+** Note that the [SQLITE_IGNORE] constant is also used as a potential
+** return value from the [sqlite3_set_authorizer()] callback and that
+** [SQLITE_ABORT] is also a [result code].
+*/
+#define SQLITE_ROLLBACK 1
+/* #define SQLITE_IGNORE 2 // Also used by sqlite3_authorizer() callback */
+#define SQLITE_FAIL     3
+/* #define SQLITE_ABORT 4  // Also an error code */
+#define SQLITE_REPLACE  5
+
+/*
+** CAPI3REF: Prepared Statement Scan Status Opcodes
+** KEYWORDS: {scanstatus options}
+**
+** The following constants can be used for the T parameter to the
+** [sqlite3_stmt_scanstatus(S,X,T,V)] interface.  Each constant designates a
+** different metric for sqlite3_stmt_scanstatus() to return.
+**
+** When the value returned to V is a string, space to hold that string is
+** managed by the prepared statement S and will be automatically freed when
+** S is finalized.
+**
+** <dl>
+** [[SQLITE_SCANSTAT_NLOOP]] <dt>SQLITE_SCANSTAT_NLOOP</dt>
+** <dd>^The [sqlite3_int64] variable pointed to by the T parameter will be
+** set to the total number of times that the X-th loop has run.</dd>
+**
+** [[SQLITE_SCANSTAT_NVISIT]] <dt>SQLITE_SCANSTAT_NVISIT</dt>
+** <dd>^The [sqlite3_int64] variable pointed to by the T parameter will be set
+** to the total number of rows examined by all iterations of the X-th loop.</dd>
+**
+** [[SQLITE_SCANSTAT_EST]] <dt>SQLITE_SCANSTAT_EST</dt>
+** <dd>^The "double" variable pointed to by the T parameter will be set to the
+** query planner's estimate for the average number of rows output from each
+** iteration of the X-th loop.  If the query planner's estimates was accurate,
+** then this value will approximate the quotient NVISIT/NLOOP and the
+** product of this value for all prior loops with the same SELECTID will
+** be the NLOOP value for the current loop.
+**
+** [[SQLITE_SCANSTAT_NAME]] <dt>SQLITE_SCANSTAT_NAME</dt>
+** <dd>^The "const char *" variable pointed to by the T parameter will be set
+** to a zero-terminated UTF-8 string containing the name of the index or table
+** used for the X-th loop.
+**
+** [[SQLITE_SCANSTAT_EXPLAIN]] <dt>SQLITE_SCANSTAT_EXPLAIN</dt>
+** <dd>^The "const char *" variable pointed to by the T parameter will be set
+** to a zero-terminated UTF-8 string containing the [EXPLAIN QUERY PLAN]
+** description for the X-th loop.
+**
+** [[SQLITE_SCANSTAT_SELECTID]] <dt>SQLITE_SCANSTAT_SELECT</dt>
+** <dd>^The "int" variable pointed to by the T parameter will be set to the
+** "select-id" for the X-th loop.  The select-id identifies which query or
+** subquery the loop is part of.  The main query has a select-id of zero.
+** The select-id is the same value as is output in the first column
+** of an [EXPLAIN QUERY PLAN] query.
+** </dl>
+*/
+#define SQLITE_SCANSTAT_NLOOP    0
+#define SQLITE_SCANSTAT_NVISIT   1
+#define SQLITE_SCANSTAT_EST      2
+#define SQLITE_SCANSTAT_NAME     3
+#define SQLITE_SCANSTAT_EXPLAIN  4
+#define SQLITE_SCANSTAT_SELECTID 5
+
+/*
+** CAPI3REF: Prepared Statement Scan Status
+** METHOD: sqlite3_stmt
+**
+** This interface returns information about the predicted and measured
+** performance for pStmt.  Advanced applications can use this
+** interface to compare the predicted and the measured performance and
+** issue warnings and/or rerun [ANALYZE] if discrepancies are found.
+**
+** Since this interface is expected to be rarely used, it is only
+** available if SQLite is compiled using the [SQLITE_ENABLE_STMT_SCANSTATUS]
+** compile-time option.
+**
+** The "iScanStatusOp" parameter determines which status information to return.
+** The "iScanStatusOp" must be one of the [scanstatus options] or the behavior
+** of this interface is undefined.
+** ^The requested measurement is written into a variable pointed to by
+** the "pOut" parameter.
+** Parameter "idx" identifies the specific loop to retrieve statistics for.
+** Loops are numbered starting from zero. ^If idx is out of range - less than
+** zero or greater than or equal to the total number of loops used to implement
+** the statement - a non-zero value is returned and the variable that pOut
+** points to is unchanged.
+**
+** ^Statistics might not be available for all loops in all statements. ^In cases
+** where there exist loops with no available statistics, this function behaves
+** as if the loop did not exist - it returns non-zero and leave the variable
+** that pOut points to unchanged.
+**
+** See also: [sqlite3_stmt_scanstatus_reset()]
+*/
+SQLITE_API int sqlite3_stmt_scanstatus(
+  sqlite3_stmt *pStmt,      /* Prepared statement for which info desired */
+  int idx,                  /* Index of loop to report on */
+  int iScanStatusOp,        /* Information desired.  SQLITE_SCANSTAT_* */
+  void *pOut                /* Result written here */
+);     
+
+/*
+** CAPI3REF: Zero Scan-Status Counters
+** METHOD: sqlite3_stmt
+**
+** ^Zero all [sqlite3_stmt_scanstatus()] related event counters.
+**
+** This API is only available if the library is built with pre-processor
+** symbol [SQLITE_ENABLE_STMT_SCANSTATUS] defined.
+*/
+SQLITE_API void sqlite3_stmt_scanstatus_reset(sqlite3_stmt*);
+
+/*
+** CAPI3REF: Flush caches to disk mid-transaction
+**
+** ^If a write-transaction is open on [database connection] D when the
+** [sqlite3_db_cacheflush(D)] interface invoked, any dirty
+** pages in the pager-cache that are not currently in use are written out 
+** to disk. A dirty page may be in use if a database cursor created by an
+** active SQL statement is reading from it, or if it is page 1 of a database
+** file (page 1 is always "in use").  ^The [sqlite3_db_cacheflush(D)]
+** interface flushes caches for all schemas - "main", "temp", and
+** any [attached] databases.
+**
+** ^If this function needs to obtain extra database locks before dirty pages 
+** can be flushed to disk, it does so. ^If those locks cannot be obtained 
+** immediately and there is a busy-handler callback configured, it is invoked
+** in the usual manner. ^If the required lock still cannot be obtained, then
+** the database is skipped and an attempt made to flush any dirty pages
+** belonging to the next (if any) database. ^If any databases are skipped
+** because locks cannot be obtained, but no other error occurs, this
+** function returns SQLITE_BUSY.
+**
+** ^If any other error occurs while flushing dirty pages to disk (for
+** example an IO error or out-of-memory condition), then processing is
+** abandoned and an SQLite [error code] is returned to the caller immediately.
+**
+** ^Otherwise, if no error occurs, [sqlite3_db_cacheflush()] returns SQLITE_OK.
+**
+** ^This function does not set the database handle error code or message
+** returned by the [sqlite3_errcode()] and [sqlite3_errmsg()] functions.
+*/
+SQLITE_API int sqlite3_db_cacheflush(sqlite3*);
+
+/*
+** CAPI3REF: The pre-update hook.
+**
+** ^These interfaces are only available if SQLite is compiled using the
+** [SQLITE_ENABLE_PREUPDATE_HOOK] compile-time option.
+**
+** ^The [sqlite3_preupdate_hook()] interface registers a callback function
+** that is invoked prior to each [INSERT], [UPDATE], and [DELETE] operation
+** on a [rowid table].
+** ^At most one preupdate hook may be registered at a time on a single
+** [database connection]; each call to [sqlite3_preupdate_hook()] overrides
+** the previous setting.
+** ^The preupdate hook is disabled by invoking [sqlite3_preupdate_hook()]
+** with a NULL pointer as the second parameter.
+** ^The third parameter to [sqlite3_preupdate_hook()] is passed through as
+** the first parameter to callbacks.
+**
+** ^The preupdate hook only fires for changes to [rowid tables]; the preupdate
+** hook is not invoked for changes to [virtual tables] or [WITHOUT ROWID]
+** tables.
+**
+** ^The second parameter to the preupdate callback is a pointer to
+** the [database connection] that registered the preupdate hook.
+** ^The third parameter to the preupdate callback is one of the constants
+** [SQLITE_INSERT], [SQLITE_DELETE], or [SQLITE_UPDATE] to identify the
+** kind of update operation that is about to occur.
+** ^(The fourth parameter to the preupdate callback is the name of the
+** database within the database connection that is being modified.  This
+** will be "main" for the main database or "temp" for TEMP tables or 
+** the name given after the AS keyword in the [ATTACH] statement for attached
+** databases.)^
+** ^The fifth parameter to the preupdate callback is the name of the
+** table that is being modified.
+** ^The sixth parameter to the preupdate callback is the initial [rowid] of the
+** row being changes for SQLITE_UPDATE and SQLITE_DELETE changes and is
+** undefined for SQLITE_INSERT changes.
+** ^The seventh parameter to the preupdate callback is the final [rowid] of
+** the row being changed for SQLITE_UPDATE and SQLITE_INSERT changes and is
+** undefined for SQLITE_DELETE changes.
+**
+** The [sqlite3_preupdate_old()], [sqlite3_preupdate_new()],
+** [sqlite3_preupdate_count()], and [sqlite3_preupdate_depth()] interfaces
+** provide additional information about a preupdate event. These routines
+** may only be called from within a preupdate callback.  Invoking any of
+** these routines from outside of a preupdate callback or with a
+** [database connection] pointer that is different from the one supplied
+** to the preupdate callback results in undefined and probably undesirable
+** behavior.
+**
+** ^The [sqlite3_preupdate_count(D)] interface returns the number of columns
+** in the row that is being inserted, updated, or deleted.
+**
+** ^The [sqlite3_preupdate_old(D,N,P)] interface writes into P a pointer to
+** a [protected sqlite3_value] that contains the value of the Nth column of
+** the table row before it is updated.  The N parameter must be between 0
+** and one less than the number of columns or the behavior will be
+** undefined. This must only be used within SQLITE_UPDATE and SQLITE_DELETE
+** preupdate callbacks; if it is used by an SQLITE_INSERT callback then the
+** behavior is undefined.  The [sqlite3_value] that P points to
+** will be destroyed when the preupdate callback returns.
+**
+** ^The [sqlite3_preupdate_new(D,N,P)] interface writes into P a pointer to
+** a [protected sqlite3_value] that contains the value of the Nth column of
+** the table row after it is updated.  The N parameter must be between 0
+** and one less than the number of columns or the behavior will be
+** undefined. This must only be used within SQLITE_INSERT and SQLITE_UPDATE
+** preupdate callbacks; if it is used by an SQLITE_DELETE callback then the
+** behavior is undefined.  The [sqlite3_value] that P points to
+** will be destroyed when the preupdate callback returns.
+**
+** ^The [sqlite3_preupdate_depth(D)] interface returns 0 if the preupdate
+** callback was invoked as a result of a direct insert, update, or delete
+** operation; or 1 for inserts, updates, or deletes invoked by top-level 
+** triggers; or 2 for changes resulting from triggers called by top-level
+** triggers; and so forth.
+**
+** See also:  [sqlite3_update_hook()]
+*/
+SQLITE_API SQLITE_EXPERIMENTAL void *sqlite3_preupdate_hook(
+  sqlite3 *db,
+  void(*xPreUpdate)(
+    void *pCtx,                   /* Copy of third arg to preupdate_hook() */
+    sqlite3 *db,                  /* Database handle */
+    int op,                       /* SQLITE_UPDATE, DELETE or INSERT */
+    char const *zDb,              /* Database name */
+    char const *zName,            /* Table name */
+    sqlite3_int64 iKey1,          /* Rowid of row about to be deleted/updated */
+    sqlite3_int64 iKey2           /* New rowid value (for a rowid UPDATE) */
+  ),
+  void*
+);
+SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_preupdate_old(sqlite3 *, int, sqlite3_value **);
+SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_preupdate_count(sqlite3 *);
+SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_preupdate_depth(sqlite3 *);
+SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_preupdate_new(sqlite3 *, int, sqlite3_value **);
+
+/*
+** CAPI3REF: Low-level system error code
+**
+** ^Attempt to return the underlying operating system error code or error
+** number that caused the most recent I/O error or failure to open a file.
+** The return value is OS-dependent.  For example, on unix systems, after
+** [sqlite3_open_v2()] returns [SQLITE_CANTOPEN], this interface could be
+** called to get back the underlying "errno" that caused the problem, such
+** as ENOSPC, EAUTH, EISDIR, and so forth.  
+*/
+SQLITE_API int sqlite3_system_errno(sqlite3*);
+
+/*
+** CAPI3REF: Database Snapshot
+** KEYWORDS: {snapshot}
+** EXPERIMENTAL
+**
+** An instance of the snapshot object records the state of a [WAL mode]
+** database for some specific point in history.
+**
+** In [WAL mode], multiple [database connections] that are open on the
+** same database file can each be reading a different historical version
+** of the database file.  When a [database connection] begins a read
+** transaction, that connection sees an unchanging copy of the database
+** as it existed for the point in time when the transaction first started.
+** Subsequent changes to the database from other connections are not seen
+** by the reader until a new read transaction is started.
+**
+** The sqlite3_snapshot object records state information about an historical
+** version of the database file so that it is possible to later open a new read
+** transaction that sees that historical version of the database rather than
+** the most recent version.
+**
+** The constructor for this object is [sqlite3_snapshot_get()].  The
+** [sqlite3_snapshot_open()] method causes a fresh read transaction to refer
+** to an historical snapshot (if possible).  The destructor for 
+** sqlite3_snapshot objects is [sqlite3_snapshot_free()].
+*/
+typedef struct sqlite3_snapshot sqlite3_snapshot;
+
+/*
+** CAPI3REF: Record A Database Snapshot
+** EXPERIMENTAL
+**
+** ^The [sqlite3_snapshot_get(D,S,P)] interface attempts to make a
+** new [sqlite3_snapshot] object that records the current state of
+** schema S in database connection D.  ^On success, the
+** [sqlite3_snapshot_get(D,S,P)] interface writes a pointer to the newly
+** created [sqlite3_snapshot] object into *P and returns SQLITE_OK.
+** ^If schema S of [database connection] D is not a [WAL mode] database
+** that is in a read transaction, then [sqlite3_snapshot_get(D,S,P)]
+** leaves the *P value unchanged and returns an appropriate [error code].
+**
+** The [sqlite3_snapshot] object returned from a successful call to
+** [sqlite3_snapshot_get()] must be freed using [sqlite3_snapshot_free()]
+** to avoid a memory leak.
+**
+** The [sqlite3_snapshot_get()] interface is only available when the
+** SQLITE_ENABLE_SNAPSHOT compile-time option is used.
+*/
+SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_snapshot_get(
+  sqlite3 *db,
+  const char *zSchema,
+  sqlite3_snapshot **ppSnapshot
+);
+
+/*
+** CAPI3REF: Start a read transaction on an historical snapshot
+** EXPERIMENTAL
+**
+** ^The [sqlite3_snapshot_open(D,S,P)] interface starts a
+** read transaction for schema S of
+** [database connection] D such that the read transaction
+** refers to historical [snapshot] P, rather than the most
+** recent change to the database.
+** ^The [sqlite3_snapshot_open()] interface returns SQLITE_OK on success
+** or an appropriate [error code] if it fails.
+**
+** ^In order to succeed, a call to [sqlite3_snapshot_open(D,S,P)] must be
+** the first operation following the [BEGIN] that takes the schema S
+** out of [autocommit mode].
+** ^In other words, schema S must not currently be in
+** a transaction for [sqlite3_snapshot_open(D,S,P)] to work, but the
+** database connection D must be out of [autocommit mode].
+** ^A [snapshot] will fail to open if it has been overwritten by a
+** [checkpoint].
+** ^(A call to [sqlite3_snapshot_open(D,S,P)] will fail if the
+** database connection D does not know that the database file for
+** schema S is in [WAL mode].  A database connection might not know
+** that the database file is in [WAL mode] if there has been no prior
+** I/O on that database connection, or if the database entered [WAL mode] 
+** after the most recent I/O on the database connection.)^
+** (Hint: Run "[PRAGMA application_id]" against a newly opened
+** database connection in order to make it ready to use snapshots.)
+**
+** The [sqlite3_snapshot_open()] interface is only available when the
+** SQLITE_ENABLE_SNAPSHOT compile-time option is used.
+*/
+SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_snapshot_open(
+  sqlite3 *db,
+  const char *zSchema,
+  sqlite3_snapshot *pSnapshot
+);
+
+/*
+** CAPI3REF: Destroy a snapshot
+** EXPERIMENTAL
+**
+** ^The [sqlite3_snapshot_free(P)] interface destroys [sqlite3_snapshot] P.
+** The application must eventually free every [sqlite3_snapshot] object
+** using this routine to avoid a memory leak.
+**
+** The [sqlite3_snapshot_free()] interface is only available when the
+** SQLITE_ENABLE_SNAPSHOT compile-time option is used.
+*/
+SQLITE_API SQLITE_EXPERIMENTAL void sqlite3_snapshot_free(sqlite3_snapshot*);
+
+/*
+** CAPI3REF: Compare the ages of two snapshot handles.
+** EXPERIMENTAL
+**
+** The sqlite3_snapshot_cmp(P1, P2) interface is used to compare the ages
+** of two valid snapshot handles. 
+**
+** If the two snapshot handles are not associated with the same database 
+** file, the result of the comparison is undefined. 
+**
+** Additionally, the result of the comparison is only valid if both of the
+** snapshot handles were obtained by calling sqlite3_snapshot_get() since the
+** last time the wal file was deleted. The wal file is deleted when the
+** database is changed back to rollback mode or when the number of database
+** clients drops to zero. If either snapshot handle was obtained before the 
+** wal file was last deleted, the value returned by this function 
+** is undefined.
+**
+** Otherwise, this API returns a negative value if P1 refers to an older
+** snapshot than P2, zero if the two handles refer to the same database
+** snapshot, and a positive value if P1 is a newer snapshot than P2.
+*/
+SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_snapshot_cmp(
+  sqlite3_snapshot *p1,
+  sqlite3_snapshot *p2
+);
+
+/*
+** Undo the hack that converts floating point types to integer for
+** builds on processors without floating point support.
+*/
+#ifdef SQLITE_OMIT_FLOATING_POINT
+# undef double
+#endif
+
+#if 0
+}  /* End of the 'extern "C"' block */
+#endif
+#endif /* SQLITE3_H */
+
+/******** Begin file sqlite3rtree.h *********/
+/*
+** 2010 August 30
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+*/
+
+#ifndef _SQLITE3RTREE_H_
+#define _SQLITE3RTREE_H_
+
+
+#if 0
+extern "C" {
+#endif
+
+typedef struct sqlite3_rtree_geometry sqlite3_rtree_geometry;
+typedef struct sqlite3_rtree_query_info sqlite3_rtree_query_info;
+
+/* The double-precision datatype used by RTree depends on the
+** SQLITE_RTREE_INT_ONLY compile-time option.
+*/
+#ifdef SQLITE_RTREE_INT_ONLY
+  typedef sqlite3_int64 sqlite3_rtree_dbl;
+#else
+  typedef double sqlite3_rtree_dbl;
+#endif
+
+/*
+** Register a geometry callback named zGeom that can be used as part of an
+** R-Tree geometry query as follows:
+**
+**   SELECT ... FROM <rtree> WHERE <rtree col> MATCH $zGeom(... params ...)
+*/
+SQLITE_API int sqlite3_rtree_geometry_callback(
+  sqlite3 *db,
+  const char *zGeom,
+  int (*xGeom)(sqlite3_rtree_geometry*, int, sqlite3_rtree_dbl*,int*),
+  void *pContext
+);
+
+
+/*
+** A pointer to a structure of the following type is passed as the first
+** argument to callbacks registered using rtree_geometry_callback().
+*/
+struct sqlite3_rtree_geometry {
+  void *pContext;                 /* Copy of pContext passed to s_r_g_c() */
+  int nParam;                     /* Size of array aParam[] */
+  sqlite3_rtree_dbl *aParam;      /* Parameters passed to SQL geom function */
+  void *pUser;                    /* Callback implementation user data */
+  void (*xDelUser)(void *);       /* Called by SQLite to clean up pUser */
+};
+
+/*
+** Register a 2nd-generation geometry callback named zScore that can be 
+** used as part of an R-Tree geometry query as follows:
+**
+**   SELECT ... FROM <rtree> WHERE <rtree col> MATCH $zQueryFunc(... params ...)
+*/
+SQLITE_API int sqlite3_rtree_query_callback(
+  sqlite3 *db,
+  const char *zQueryFunc,
+  int (*xQueryFunc)(sqlite3_rtree_query_info*),
+  void *pContext,
+  void (*xDestructor)(void*)
+);
+
+
+/*
+** A pointer to a structure of the following type is passed as the 
+** argument to scored geometry callback registered using
+** sqlite3_rtree_query_callback().
+**
+** Note that the first 5 fields of this structure are identical to
+** sqlite3_rtree_geometry.  This structure is a subclass of
+** sqlite3_rtree_geometry.
+*/
+struct sqlite3_rtree_query_info {
+  void *pContext;                   /* pContext from when function registered */
+  int nParam;                       /* Number of function parameters */
+  sqlite3_rtree_dbl *aParam;        /* value of function parameters */
+  void *pUser;                      /* callback can use this, if desired */
+  void (*xDelUser)(void*);          /* function to free pUser */
+  sqlite3_rtree_dbl *aCoord;        /* Coordinates of node or entry to check */
+  unsigned int *anQueue;            /* Number of pending entries in the queue */
+  int nCoord;                       /* Number of coordinates */
+  int iLevel;                       /* Level of current node or entry */
+  int mxLevel;                      /* The largest iLevel value in the tree */
+  sqlite3_int64 iRowid;             /* Rowid for current entry */
+  sqlite3_rtree_dbl rParentScore;   /* Score of parent node */
+  int eParentWithin;                /* Visibility of parent node */
+  int eWithin;                      /* OUT: Visiblity */
+  sqlite3_rtree_dbl rScore;         /* OUT: Write the score here */
+  /* The following fields are only available in 3.8.11 and later */
+  sqlite3_value **apSqlParam;       /* Original SQL values of parameters */
+};
+
+/*
+** Allowed values for sqlite3_rtree_query.eWithin and .eParentWithin.
+*/
+#define NOT_WITHIN       0   /* Object completely outside of query region */
+#define PARTLY_WITHIN    1   /* Object partially overlaps query region */
+#define FULLY_WITHIN     2   /* Object fully contained within query region */
+
+
+#if 0
+}  /* end of the 'extern "C"' block */
+#endif
+
+#endif  /* ifndef _SQLITE3RTREE_H_ */
+
+/******** End of sqlite3rtree.h *********/
+/******** Begin file sqlite3session.h *********/
+
+#if !defined(__SQLITESESSION_H_) && defined(SQLITE_ENABLE_SESSION)
+#define __SQLITESESSION_H_ 1
+
+/*
+** Make sure we can call this stuff from C++.
+*/
+#if 0
+extern "C" {
+#endif
+
+
+/*
+** CAPI3REF: Session Object Handle
+*/
+typedef struct sqlite3_session sqlite3_session;
+
+/*
+** CAPI3REF: Changeset Iterator Handle
+*/
+typedef struct sqlite3_changeset_iter sqlite3_changeset_iter;
+
+/*
+** CAPI3REF: Create A New Session Object
+**
+** Create a new session object attached to database handle db. If successful,
+** a pointer to the new object is written to *ppSession and SQLITE_OK is
+** returned. If an error occurs, *ppSession is set to NULL and an SQLite
+** error code (e.g. SQLITE_NOMEM) is returned.
+**
+** It is possible to create multiple session objects attached to a single
+** database handle.
+**
+** Session objects created using this function should be deleted using the
+** [sqlite3session_delete()] function before the database handle that they
+** are attached to is itself closed. If the database handle is closed before
+** the session object is deleted, then the results of calling any session
+** module function, including [sqlite3session_delete()] on the session object
+** are undefined.
+**
+** Because the session module uses the [sqlite3_preupdate_hook()] API, it
+** is not possible for an application to register a pre-update hook on a
+** database handle that has one or more session objects attached. Nor is
+** it possible to create a session object attached to a database handle for
+** which a pre-update hook is already defined. The results of attempting 
+** either of these things are undefined.
+**
+** The session object will be used to create changesets for tables in
+** database zDb, where zDb is either "main", or "temp", or the name of an
+** attached database. It is not an error if database zDb is not attached
+** to the database when the session object is created.
+*/
+int sqlite3session_create(
+  sqlite3 *db,                    /* Database handle */
+  const char *zDb,                /* Name of db (e.g. "main") */
+  sqlite3_session **ppSession     /* OUT: New session object */
+);
+
+/*
+** CAPI3REF: Delete A Session Object
+**
+** Delete a session object previously allocated using 
+** [sqlite3session_create()]. Once a session object has been deleted, the
+** results of attempting to use pSession with any other session module
+** function are undefined.
+**
+** Session objects must be deleted before the database handle to which they
+** are attached is closed. Refer to the documentation for 
+** [sqlite3session_create()] for details.
+*/
+void sqlite3session_delete(sqlite3_session *pSession);
+
+
+/*
+** CAPI3REF: Enable Or Disable A Session Object
+**
+** Enable or disable the recording of changes by a session object. When
+** enabled, a session object records changes made to the database. When
+** disabled - it does not. A newly created session object is enabled.
+** Refer to the documentation for [sqlite3session_changeset()] for further
+** details regarding how enabling and disabling a session object affects
+** the eventual changesets.
+**
+** Passing zero to this function disables the session. Passing a value
+** greater than zero enables it. Passing a value less than zero is a 
+** no-op, and may be used to query the current state of the session.
+**
+** The return value indicates the final state of the session object: 0 if 
+** the session is disabled, or 1 if it is enabled.
+*/
+int sqlite3session_enable(sqlite3_session *pSession, int bEnable);
+
+/*
+** CAPI3REF: Set Or Clear the Indirect Change Flag
+**
+** Each change recorded by a session object is marked as either direct or
+** indirect. A change is marked as indirect if either:
+**
+** <ul>
+**   <li> The session object "indirect" flag is set when the change is
+**        made, or
+**   <li> The change is made by an SQL trigger or foreign key action 
+**        instead of directly as a result of a users SQL statement.
+** </ul>
+**
+** If a single row is affected by more than one operation within a session,
+** then the change is considered indirect if all operations meet the criteria
+** for an indirect change above, or direct otherwise.
+**
+** This function is used to set, clear or query the session object indirect
+** flag.  If the second argument passed to this function is zero, then the
+** indirect flag is cleared. If it is greater than zero, the indirect flag
+** is set. Passing a value less than zero does not modify the current value
+** of the indirect flag, and may be used to query the current state of the 
+** indirect flag for the specified session object.
+**
+** The return value indicates the final state of the indirect flag: 0 if 
+** it is clear, or 1 if it is set.
+*/
+int sqlite3session_indirect(sqlite3_session *pSession, int bIndirect);
+
+/*
+** CAPI3REF: Attach A Table To A Session Object
+**
+** If argument zTab is not NULL, then it is the name of a table to attach
+** to the session object passed as the first argument. All subsequent changes 
+** made to the table while the session object is enabled will be recorded. See 
+** documentation for [sqlite3session_changeset()] for further details.
+**
+** Or, if argument zTab is NULL, then changes are recorded for all tables
+** in the database. If additional tables are added to the database (by 
+** executing "CREATE TABLE" statements) after this call is made, changes for 
+** the new tables are also recorded.
+**
+** Changes can only be recorded for tables that have a PRIMARY KEY explicitly
+** defined as part of their CREATE TABLE statement. It does not matter if the 
+** PRIMARY KEY is an "INTEGER PRIMARY KEY" (rowid alias) or not. The PRIMARY
+** KEY may consist of a single column, or may be a composite key.
+** 
+** It is not an error if the named table does not exist in the database. Nor
+** is it an error if the named table does not have a PRIMARY KEY. However,
+** no changes will be recorded in either of these scenarios.
+**
+** Changes are not recorded for individual rows that have NULL values stored
+** in one or more of their PRIMARY KEY columns.
+**
+** SQLITE_OK is returned if the call completes without error. Or, if an error 
+** occurs, an SQLite error code (e.g. SQLITE_NOMEM) is returned.
+*/
+int sqlite3session_attach(
+  sqlite3_session *pSession,      /* Session object */
+  const char *zTab                /* Table name */
+);
+
+/*
+** CAPI3REF: Set a table filter on a Session Object.
+**
+** The second argument (xFilter) is the "filter callback". For changes to rows 
+** in tables that are not attached to the Session object, the filter is called
+** to determine whether changes to the table's rows should be tracked or not. 
+** If xFilter returns 0, changes is not tracked. Note that once a table is 
+** attached, xFilter will not be called again.
+*/
+void sqlite3session_table_filter(
+  sqlite3_session *pSession,      /* Session object */
+  int(*xFilter)(
+    void *pCtx,                   /* Copy of third arg to _filter_table() */
+    const char *zTab              /* Table name */
+  ),
+  void *pCtx                      /* First argument passed to xFilter */
+);
+
+/*
+** CAPI3REF: Generate A Changeset From A Session Object
+**
+** Obtain a changeset containing changes to the tables attached to the 
+** session object passed as the first argument. If successful, 
+** set *ppChangeset to point to a buffer containing the changeset 
+** and *pnChangeset to the size of the changeset in bytes before returning
+** SQLITE_OK. If an error occurs, set both *ppChangeset and *pnChangeset to
+** zero and return an SQLite error code.
+**
+** A changeset consists of zero or more INSERT, UPDATE and/or DELETE changes,
+** each representing a change to a single row of an attached table. An INSERT
+** change contains the values of each field of a new database row. A DELETE
+** contains the original values of each field of a deleted database row. An
+** UPDATE change contains the original values of each field of an updated
+** database row along with the updated values for each updated non-primary-key
+** column. It is not possible for an UPDATE change to represent a change that
+** modifies the values of primary key columns. If such a change is made, it
+** is represented in a changeset as a DELETE followed by an INSERT.
+**
+** Changes are not recorded for rows that have NULL values stored in one or 
+** more of their PRIMARY KEY columns. If such a row is inserted or deleted,
+** no corresponding change is present in the changesets returned by this
+** function. If an existing row with one or more NULL values stored in
+** PRIMARY KEY columns is updated so that all PRIMARY KEY columns are non-NULL,
+** only an INSERT is appears in the changeset. Similarly, if an existing row
+** with non-NULL PRIMARY KEY values is updated so that one or more of its
+** PRIMARY KEY columns are set to NULL, the resulting changeset contains a
+** DELETE change only.
+**
+** The contents of a changeset may be traversed using an iterator created
+** using the [sqlite3changeset_start()] API. A changeset may be applied to
+** a database with a compatible schema using the [sqlite3changeset_apply()]
+** API.
+**
+** Within a changeset generated by this function, all changes related to a
+** single table are grouped together. In other words, when iterating through
+** a changeset or when applying a changeset to a database, all changes related
+** to a single table are processed before moving on to the next table. Tables
+** are sorted in the same order in which they were attached (or auto-attached)
+** to the sqlite3_session object. The order in which the changes related to
+** a single table are stored is undefined.
+**
+** Following a successful call to this function, it is the responsibility of
+** the caller to eventually free the buffer that *ppChangeset points to using
+** [sqlite3_free()].
+**
+** <h3>Changeset Generation</h3>
+**
+** Once a table has been attached to a session object, the session object
+** records the primary key values of all new rows inserted into the table.
+** It also records the original primary key and other column values of any
+** deleted or updated rows. For each unique primary key value, data is only
+** recorded once - the first time a row with said primary key is inserted,
+** updated or deleted in the lifetime of the session.
+**
+** There is one exception to the previous paragraph: when a row is inserted,
+** updated or deleted, if one or more of its primary key columns contain a
+** NULL value, no record of the change is made.
+**
+** The session object therefore accumulates two types of records - those
+** that consist of primary key values only (created when the user inserts
+** a new record) and those that consist of the primary key values and the
+** original values of other table columns (created when the users deletes
+** or updates a record).
+**
+** When this function is called, the requested changeset is created using
+** both the accumulated records and the current contents of the database
+** file. Specifically:
+**
+** <ul>
+**   <li> For each record generated by an insert, the database is queried
+**        for a row with a matching primary key. If one is found, an INSERT
+**        change is added to the changeset. If no such row is found, no change 
+**        is added to the changeset.
+**
+**   <li> For each record generated by an update or delete, the database is 
+**        queried for a row with a matching primary key. If such a row is
+**        found and one or more of the non-primary key fields have been
+**        modified from their original values, an UPDATE change is added to 
+**        the changeset. Or, if no such row is found in the table, a DELETE 
+**        change is added to the changeset. If there is a row with a matching
+**        primary key in the database, but all fields contain their original
+**        values, no change is added to the changeset.
+** </ul>
+**
+** This means, amongst other things, that if a row is inserted and then later
+** deleted while a session object is active, neither the insert nor the delete
+** will be present in the changeset. Or if a row is deleted and then later a 
+** row with the same primary key values inserted while a session object is
+** active, the resulting changeset will contain an UPDATE change instead of
+** a DELETE and an INSERT.
+**
+** When a session object is disabled (see the [sqlite3session_enable()] API),
+** it does not accumulate records when rows are inserted, updated or deleted.
+** This may appear to have some counter-intuitive effects if a single row
+** is written to more than once during a session. For example, if a row
+** is inserted while a session object is enabled, then later deleted while 
+** the same session object is disabled, no INSERT record will appear in the
+** changeset, even though the delete took place while the session was disabled.
+** Or, if one field of a row is updated while a session is disabled, and 
+** another field of the same row is updated while the session is enabled, the
+** resulting changeset will contain an UPDATE change that updates both fields.
+*/
+int sqlite3session_changeset(
+  sqlite3_session *pSession,      /* Session object */
+  int *pnChangeset,               /* OUT: Size of buffer at *ppChangeset */
+  void **ppChangeset              /* OUT: Buffer containing changeset */
+);
+
+/*
+** CAPI3REF: Load The Difference Between Tables Into A Session 
+**
+** If it is not already attached to the session object passed as the first
+** argument, this function attaches table zTbl in the same manner as the
+** [sqlite3session_attach()] function. If zTbl does not exist, or if it
+** does not have a primary key, this function is a no-op (but does not return
+** an error).
+**
+** Argument zFromDb must be the name of a database ("main", "temp" etc.)
+** attached to the same database handle as the session object that contains 
+** a table compatible with the table attached to the session by this function.
+** A table is considered compatible if it:
+**
+** <ul>
+**   <li> Has the same name,
+**   <li> Has the same set of columns declared in the same order, and
+**   <li> Has the same PRIMARY KEY definition.
+** </ul>
+**
+** If the tables are not compatible, SQLITE_SCHEMA is returned. If the tables
+** are compatible but do not have any PRIMARY KEY columns, it is not an error
+** but no changes are added to the session object. As with other session
+** APIs, tables without PRIMARY KEYs are simply ignored.
+**
+** This function adds a set of changes to the session object that could be
+** used to update the table in database zFrom (call this the "from-table") 
+** so that its content is the same as the table attached to the session 
+** object (call this the "to-table"). Specifically:
+**
+** <ul>
+**   <li> For each row (primary key) that exists in the to-table but not in 
+**     the from-table, an INSERT record is added to the session object.
+**
+**   <li> For each row (primary key) that exists in the to-table but not in 
+**     the from-table, a DELETE record is added to the session object.
+**
+**   <li> For each row (primary key) that exists in both tables, but features 
+**     different in each, an UPDATE record is added to the session.
+** </ul>
+**
+** To clarify, if this function is called and then a changeset constructed
+** using [sqlite3session_changeset()], then after applying that changeset to 
+** database zFrom the contents of the two compatible tables would be 
+** identical.
+**
+** It an error if database zFrom does not exist or does not contain the
+** required compatible table.
+**
+** If the operation successful, SQLITE_OK is returned. Otherwise, an SQLite
+** error code. In this case, if argument pzErrMsg is not NULL, *pzErrMsg
+** may be set to point to a buffer containing an English language error 
+** message. It is the responsibility of the caller to free this buffer using
+** sqlite3_free().
+*/
+int sqlite3session_diff(
+  sqlite3_session *pSession,
+  const char *zFromDb,
+  const char *zTbl,
+  char **pzErrMsg
+);
+
+
+/*
+** CAPI3REF: Generate A Patchset From A Session Object
+**
+** The differences between a patchset and a changeset are that:
+**
+** <ul>
+**   <li> DELETE records consist of the primary key fields only. The 
+**        original values of other fields are omitted.
+**   <li> The original values of any modified fields are omitted from 
+**        UPDATE records.
+** </ul>
+**
+** A patchset blob may be used with up to date versions of all 
+** sqlite3changeset_xxx API functions except for sqlite3changeset_invert(), 
+** which returns SQLITE_CORRUPT if it is passed a patchset. Similarly,
+** attempting to use a patchset blob with old versions of the
+** sqlite3changeset_xxx APIs also provokes an SQLITE_CORRUPT error. 
+**
+** Because the non-primary key "old.*" fields are omitted, no 
+** SQLITE_CHANGESET_DATA conflicts can be detected or reported if a patchset
+** is passed to the sqlite3changeset_apply() API. Other conflict types work
+** in the same way as for changesets.
+**
+** Changes within a patchset are ordered in the same way as for changesets
+** generated by the sqlite3session_changeset() function (i.e. all changes for
+** a single table are grouped together, tables appear in the order in which
+** they were attached to the session object).
+*/
+int sqlite3session_patchset(
+  sqlite3_session *pSession,      /* Session object */
+  int *pnPatchset,                /* OUT: Size of buffer at *ppChangeset */
+  void **ppPatchset               /* OUT: Buffer containing changeset */
+);
+
+/*
+** CAPI3REF: Test if a changeset has recorded any changes.
+**
+** Return non-zero if no changes to attached tables have been recorded by 
+** the session object passed as the first argument. Otherwise, if one or 
+** more changes have been recorded, return zero.
+**
+** Even if this function returns zero, it is possible that calling
+** [sqlite3session_changeset()] on the session handle may still return a
+** changeset that contains no changes. This can happen when a row in 
+** an attached table is modified and then later on the original values 
+** are restored. However, if this function returns non-zero, then it is
+** guaranteed that a call to sqlite3session_changeset() will return a 
+** changeset containing zero changes.
+*/
+int sqlite3session_isempty(sqlite3_session *pSession);
+
+/*
+** CAPI3REF: Create An Iterator To Traverse A Changeset 
+**
+** Create an iterator used to iterate through the contents of a changeset.
+** If successful, *pp is set to point to the iterator handle and SQLITE_OK
+** is returned. Otherwise, if an error occurs, *pp is set to zero and an
+** SQLite error code is returned.
+**
+** The following functions can be used to advance and query a changeset 
+** iterator created by this function:
+**
+** <ul>
+**   <li> [sqlite3changeset_next()]
+**   <li> [sqlite3changeset_op()]
+**   <li> [sqlite3changeset_new()]
+**   <li> [sqlite3changeset_old()]
+** </ul>
+**
+** It is the responsibility of the caller to eventually destroy the iterator
+** by passing it to [sqlite3changeset_finalize()]. The buffer containing the
+** changeset (pChangeset) must remain valid until after the iterator is
+** destroyed.
+**
+** Assuming the changeset blob was created by one of the
+** [sqlite3session_changeset()], [sqlite3changeset_concat()] or
+** [sqlite3changeset_invert()] functions, all changes within the changeset 
+** that apply to a single table are grouped together. This means that when 
+** an application iterates through a changeset using an iterator created by 
+** this function, all changes that relate to a single table are visited 
+** consecutively. There is no chance that the iterator will visit a change 
+** the applies to table X, then one for table Y, and then later on visit 
+** another change for table X.
+*/
+int sqlite3changeset_start(
+  sqlite3_changeset_iter **pp,    /* OUT: New changeset iterator handle */
+  int nChangeset,                 /* Size of changeset blob in bytes */
+  void *pChangeset                /* Pointer to blob containing changeset */
+);
+
+
+/*
+** CAPI3REF: Advance A Changeset Iterator
+**
+** This function may only be used with iterators created by function
+** [sqlite3changeset_start()]. If it is called on an iterator passed to
+** a conflict-handler callback by [sqlite3changeset_apply()], SQLITE_MISUSE
+** is returned and the call has no effect.
+**
+** Immediately after an iterator is created by sqlite3changeset_start(), it
+** does not point to any change in the changeset. Assuming the changeset
+** is not empty, the first call to this function advances the iterator to
+** point to the first change in the changeset. Each subsequent call advances
+** the iterator to point to the next change in the changeset (if any). If
+** no error occurs and the iterator points to a valid change after a call
+** to sqlite3changeset_next() has advanced it, SQLITE_ROW is returned. 
+** Otherwise, if all changes in the changeset have already been visited,
+** SQLITE_DONE is returned.
+**
+** If an error occurs, an SQLite error code is returned. Possible error 
+** codes include SQLITE_CORRUPT (if the changeset buffer is corrupt) or 
+** SQLITE_NOMEM.
+*/
+int sqlite3changeset_next(sqlite3_changeset_iter *pIter);
+
+/*
+** CAPI3REF: Obtain The Current Operation From A Changeset Iterator
+**
+** The pIter argument passed to this function may either be an iterator
+** passed to a conflict-handler by [sqlite3changeset_apply()], or an iterator
+** created by [sqlite3changeset_start()]. In the latter case, the most recent
+** call to [sqlite3changeset_next()] must have returned [SQLITE_ROW]. If this
+** is not the case, this function returns [SQLITE_MISUSE].
+**
+** If argument pzTab is not NULL, then *pzTab is set to point to a
+** nul-terminated utf-8 encoded string containing the name of the table
+** affected by the current change. The buffer remains valid until either
+** sqlite3changeset_next() is called on the iterator or until the 
+** conflict-handler function returns. If pnCol is not NULL, then *pnCol is 
+** set to the number of columns in the table affected by the change. If
+** pbIncorrect is not NULL, then *pbIndirect is set to true (1) if the change
+** is an indirect change, or false (0) otherwise. See the documentation for
+** [sqlite3session_indirect()] for a description of direct and indirect
+** changes. Finally, if pOp is not NULL, then *pOp is set to one of 
+** [SQLITE_INSERT], [SQLITE_DELETE] or [SQLITE_UPDATE], depending on the 
+** type of change that the iterator currently points to.
+**
+** If no error occurs, SQLITE_OK is returned. If an error does occur, an
+** SQLite error code is returned. The values of the output variables may not
+** be trusted in this case.
+*/
+int sqlite3changeset_op(
+  sqlite3_changeset_iter *pIter,  /* Iterator object */
+  const char **pzTab,             /* OUT: Pointer to table name */
+  int *pnCol,                     /* OUT: Number of columns in table */
+  int *pOp,                       /* OUT: SQLITE_INSERT, DELETE or UPDATE */
+  int *pbIndirect                 /* OUT: True for an 'indirect' change */
+);
+
+/*
+** CAPI3REF: Obtain The Primary Key Definition Of A Table
+**
+** For each modified table, a changeset includes the following:
+**
+** <ul>
+**   <li> The number of columns in the table, and
+**   <li> Which of those columns make up the tables PRIMARY KEY.
+** </ul>
+**
+** This function is used to find which columns comprise the PRIMARY KEY of
+** the table modified by the change that iterator pIter currently points to.
+** If successful, *pabPK is set to point to an array of nCol entries, where
+** nCol is the number of columns in the table. Elements of *pabPK are set to
+** 0x01 if the corresponding column is part of the tables primary key, or
+** 0x00 if it is not.
+**
+** If argument pnCol is not NULL, then *pnCol is set to the number of columns
+** in the table.
+**
+** If this function is called when the iterator does not point to a valid
+** entry, SQLITE_MISUSE is returned and the output variables zeroed. Otherwise,
+** SQLITE_OK is returned and the output variables populated as described
+** above.
+*/
+int sqlite3changeset_pk(
+  sqlite3_changeset_iter *pIter,  /* Iterator object */
+  unsigned char **pabPK,          /* OUT: Array of boolean - true for PK cols */
+  int *pnCol                      /* OUT: Number of entries in output array */
+);
+
+/*
+** CAPI3REF: Obtain old.* Values From A Changeset Iterator
+**
+** The pIter argument passed to this function may either be an iterator
+** passed to a conflict-handler by [sqlite3changeset_apply()], or an iterator
+** created by [sqlite3changeset_start()]. In the latter case, the most recent
+** call to [sqlite3changeset_next()] must have returned SQLITE_ROW. 
+** Furthermore, it may only be called if the type of change that the iterator
+** currently points to is either [SQLITE_DELETE] or [SQLITE_UPDATE]. Otherwise,
+** this function returns [SQLITE_MISUSE] and sets *ppValue to NULL.
+**
+** Argument iVal must be greater than or equal to 0, and less than the number
+** of columns in the table affected by the current change. Otherwise,
+** [SQLITE_RANGE] is returned and *ppValue is set to NULL.
+**
+** If successful, this function sets *ppValue to point to a protected
+** sqlite3_value object containing the iVal'th value from the vector of 
+** original row values stored as part of the UPDATE or DELETE change and
+** returns SQLITE_OK. The name of the function comes from the fact that this 
+** is similar to the "old.*" columns available to update or delete triggers.
+**
+** If some other error occurs (e.g. an OOM condition), an SQLite error code
+** is returned and *ppValue is set to NULL.
+*/
+int sqlite3changeset_old(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int iVal,                       /* Column number */
+  sqlite3_value **ppValue         /* OUT: Old value (or NULL pointer) */
+);
+
+/*
+** CAPI3REF: Obtain new.* Values From A Changeset Iterator
+**
+** The pIter argument passed to this function may either be an iterator
+** passed to a conflict-handler by [sqlite3changeset_apply()], or an iterator
+** created by [sqlite3changeset_start()]. In the latter case, the most recent
+** call to [sqlite3changeset_next()] must have returned SQLITE_ROW. 
+** Furthermore, it may only be called if the type of change that the iterator
+** currently points to is either [SQLITE_UPDATE] or [SQLITE_INSERT]. Otherwise,
+** this function returns [SQLITE_MISUSE] and sets *ppValue to NULL.
+**
+** Argument iVal must be greater than or equal to 0, and less than the number
+** of columns in the table affected by the current change. Otherwise,
+** [SQLITE_RANGE] is returned and *ppValue is set to NULL.
+**
+** If successful, this function sets *ppValue to point to a protected
+** sqlite3_value object containing the iVal'th value from the vector of 
+** new row values stored as part of the UPDATE or INSERT change and
+** returns SQLITE_OK. If the change is an UPDATE and does not include
+** a new value for the requested column, *ppValue is set to NULL and 
+** SQLITE_OK returned. The name of the function comes from the fact that 
+** this is similar to the "new.*" columns available to update or delete 
+** triggers.
+**
+** If some other error occurs (e.g. an OOM condition), an SQLite error code
+** is returned and *ppValue is set to NULL.
+*/
+int sqlite3changeset_new(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int iVal,                       /* Column number */
+  sqlite3_value **ppValue         /* OUT: New value (or NULL pointer) */
+);
+
+/*
+** CAPI3REF: Obtain Conflicting Row Values From A Changeset Iterator
+**
+** This function should only be used with iterator objects passed to a
+** conflict-handler callback by [sqlite3changeset_apply()] with either
+** [SQLITE_CHANGESET_DATA] or [SQLITE_CHANGESET_CONFLICT]. If this function
+** is called on any other iterator, [SQLITE_MISUSE] is returned and *ppValue
+** is set to NULL.
+**
+** Argument iVal must be greater than or equal to 0, and less than the number
+** of columns in the table affected by the current change. Otherwise,
+** [SQLITE_RANGE] is returned and *ppValue is set to NULL.
+**
+** If successful, this function sets *ppValue to point to a protected
+** sqlite3_value object containing the iVal'th value from the 
+** "conflicting row" associated with the current conflict-handler callback
+** and returns SQLITE_OK.
+**
+** If some other error occurs (e.g. an OOM condition), an SQLite error code
+** is returned and *ppValue is set to NULL.
+*/
+int sqlite3changeset_conflict(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int iVal,                       /* Column number */
+  sqlite3_value **ppValue         /* OUT: Value from conflicting row */
+);
+
+/*
+** CAPI3REF: Determine The Number Of Foreign Key Constraint Violations
+**
+** This function may only be called with an iterator passed to an
+** SQLITE_CHANGESET_FOREIGN_KEY conflict handler callback. In this case
+** it sets the output variable to the total number of known foreign key
+** violations in the destination database and returns SQLITE_OK.
+**
+** In all other cases this function returns SQLITE_MISUSE.
+*/
+int sqlite3changeset_fk_conflicts(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int *pnOut                      /* OUT: Number of FK violations */
+);
+
+
+/*
+** CAPI3REF: Finalize A Changeset Iterator
+**
+** This function is used to finalize an iterator allocated with
+** [sqlite3changeset_start()].
+**
+** This function should only be called on iterators created using the
+** [sqlite3changeset_start()] function. If an application calls this
+** function with an iterator passed to a conflict-handler by
+** [sqlite3changeset_apply()], [SQLITE_MISUSE] is immediately returned and the
+** call has no effect.
+**
+** If an error was encountered within a call to an sqlite3changeset_xxx()
+** function (for example an [SQLITE_CORRUPT] in [sqlite3changeset_next()] or an 
+** [SQLITE_NOMEM] in [sqlite3changeset_new()]) then an error code corresponding
+** to that error is returned by this function. Otherwise, SQLITE_OK is
+** returned. This is to allow the following pattern (pseudo-code):
+**
+**   sqlite3changeset_start();
+**   while( SQLITE_ROW==sqlite3changeset_next() ){
+**     // Do something with change.
+**   }
+**   rc = sqlite3changeset_finalize();
+**   if( rc!=SQLITE_OK ){
+**     // An error has occurred 
+**   }
+*/
+int sqlite3changeset_finalize(sqlite3_changeset_iter *pIter);
+
+/*
+** CAPI3REF: Invert A Changeset
+**
+** This function is used to "invert" a changeset object. Applying an inverted
+** changeset to a database reverses the effects of applying the uninverted
+** changeset. Specifically:
+**
+** <ul>
+**   <li> Each DELETE change is changed to an INSERT, and
+**   <li> Each INSERT change is changed to a DELETE, and
+**   <li> For each UPDATE change, the old.* and new.* values are exchanged.
+** </ul>
+**
+** This function does not change the order in which changes appear within
+** the changeset. It merely reverses the sense of each individual change.
+**
+** If successful, a pointer to a buffer containing the inverted changeset
+** is stored in *ppOut, the size of the same buffer is stored in *pnOut, and
+** SQLITE_OK is returned. If an error occurs, both *pnOut and *ppOut are
+** zeroed and an SQLite error code returned.
+**
+** It is the responsibility of the caller to eventually call sqlite3_free()
+** on the *ppOut pointer to free the buffer allocation following a successful 
+** call to this function.
+**
+** WARNING/TODO: This function currently assumes that the input is a valid
+** changeset. If it is not, the results are undefined.
+*/
+int sqlite3changeset_invert(
+  int nIn, const void *pIn,       /* Input changeset */
+  int *pnOut, void **ppOut        /* OUT: Inverse of input */
+);
+
+/*
+** CAPI3REF: Concatenate Two Changeset Objects
+**
+** This function is used to concatenate two changesets, A and B, into a 
+** single changeset. The result is a changeset equivalent to applying
+** changeset A followed by changeset B. 
+**
+** This function combines the two input changesets using an 
+** sqlite3_changegroup object. Calling it produces similar results as the
+** following code fragment:
+**
+**   sqlite3_changegroup *pGrp;
+**   rc = sqlite3_changegroup_new(&pGrp);
+**   if( rc==SQLITE_OK ) rc = sqlite3changegroup_add(pGrp, nA, pA);
+**   if( rc==SQLITE_OK ) rc = sqlite3changegroup_add(pGrp, nB, pB);
+**   if( rc==SQLITE_OK ){
+**     rc = sqlite3changegroup_output(pGrp, pnOut, ppOut);
+**   }else{
+**     *ppOut = 0;
+**     *pnOut = 0;
+**   }
+**
+** Refer to the sqlite3_changegroup documentation below for details.
+*/
+int sqlite3changeset_concat(
+  int nA,                         /* Number of bytes in buffer pA */
+  void *pA,                       /* Pointer to buffer containing changeset A */
+  int nB,                         /* Number of bytes in buffer pB */
+  void *pB,                       /* Pointer to buffer containing changeset B */
+  int *pnOut,                     /* OUT: Number of bytes in output changeset */
+  void **ppOut                    /* OUT: Buffer containing output changeset */
+);
+
+
+/*
+** CAPI3REF: Changegroup Handle
+*/
+typedef struct sqlite3_changegroup sqlite3_changegroup;
+
+/*
+** CAPI3REF: Create A New Changegroup Object
+**
+** An sqlite3_changegroup object is used to combine two or more changesets
+** (or patchsets) into a single changeset (or patchset). A single changegroup
+** object may combine changesets or patchsets, but not both. The output is
+** always in the same format as the input.
+**
+** If successful, this function returns SQLITE_OK and populates (*pp) with
+** a pointer to a new sqlite3_changegroup object before returning. The caller
+** should eventually free the returned object using a call to 
+** sqlite3changegroup_delete(). If an error occurs, an SQLite error code
+** (i.e. SQLITE_NOMEM) is returned and *pp is set to NULL.
+**
+** The usual usage pattern for an sqlite3_changegroup object is as follows:
+**
+** <ul>
+**   <li> It is created using a call to sqlite3changegroup_new().
+**
+**   <li> Zero or more changesets (or patchsets) are added to the object
+**        by calling sqlite3changegroup_add().
+**
+**   <li> The result of combining all input changesets together is obtained 
+**        by the application via a call to sqlite3changegroup_output().
+**
+**   <li> The object is deleted using a call to sqlite3changegroup_delete().
+** </ul>
+**
+** Any number of calls to add() and output() may be made between the calls to
+** new() and delete(), and in any order.
+**
+** As well as the regular sqlite3changegroup_add() and 
+** sqlite3changegroup_output() functions, also available are the streaming
+** versions sqlite3changegroup_add_strm() and sqlite3changegroup_output_strm().
+*/
+int sqlite3changegroup_new(sqlite3_changegroup **pp);
+
+/*
+** CAPI3REF: Add A Changeset To A Changegroup
+**
+** Add all changes within the changeset (or patchset) in buffer pData (size
+** nData bytes) to the changegroup. 
+**
+** If the buffer contains a patchset, then all prior calls to this function
+** on the same changegroup object must also have specified patchsets. Or, if
+** the buffer contains a changeset, so must have the earlier calls to this
+** function. Otherwise, SQLITE_ERROR is returned and no changes are added
+** to the changegroup.
+**
+** Rows within the changeset and changegroup are identified by the values in
+** their PRIMARY KEY columns. A change in the changeset is considered to
+** apply to the same row as a change already present in the changegroup if
+** the two rows have the same primary key.
+**
+** Changes to rows that do not already appear in the changegroup are
+** simply copied into it. Or, if both the new changeset and the changegroup
+** contain changes that apply to a single row, the final contents of the
+** changegroup depends on the type of each change, as follows:
+**
+** <table border=1 style="margin-left:8ex;margin-right:8ex">
+**   <tr><th style="white-space:pre">Existing Change  </th>
+**       <th style="white-space:pre">New Change       </th>
+**       <th>Output Change
+**   <tr><td>INSERT <td>INSERT <td>
+**       The new change is ignored. This case does not occur if the new
+**       changeset was recorded immediately after the changesets already
+**       added to the changegroup.
+**   <tr><td>INSERT <td>UPDATE <td>
+**       The INSERT change remains in the changegroup. The values in the 
+**       INSERT change are modified as if the row was inserted by the
+**       existing change and then updated according to the new change.
+**   <tr><td>INSERT <td>DELETE <td>
+**       The existing INSERT is removed from the changegroup. The DELETE is
+**       not added.
+**   <tr><td>UPDATE <td>INSERT <td>
+**       The new change is ignored. This case does not occur if the new
+**       changeset was recorded immediately after the changesets already
+**       added to the changegroup.
+**   <tr><td>UPDATE <td>UPDATE <td>
+**       The existing UPDATE remains within the changegroup. It is amended 
+**       so that the accompanying values are as if the row was updated once 
+**       by the existing change and then again by the new change.
+**   <tr><td>UPDATE <td>DELETE <td>
+**       The existing UPDATE is replaced by the new DELETE within the
+**       changegroup.
+**   <tr><td>DELETE <td>INSERT <td>
+**       If one or more of the column values in the row inserted by the
+**       new change differ from those in the row deleted by the existing 
+**       change, the existing DELETE is replaced by an UPDATE within the
+**       changegroup. Otherwise, if the inserted row is exactly the same 
+**       as the deleted row, the existing DELETE is simply discarded.
+**   <tr><td>DELETE <td>UPDATE <td>
+**       The new change is ignored. This case does not occur if the new
+**       changeset was recorded immediately after the changesets already
+**       added to the changegroup.
+**   <tr><td>DELETE <td>DELETE <td>
+**       The new change is ignored. This case does not occur if the new
+**       changeset was recorded immediately after the changesets already
+**       added to the changegroup.
+** </table>
+**
+** If the new changeset contains changes to a table that is already present
+** in the changegroup, then the number of columns and the position of the
+** primary key columns for the table must be consistent. If this is not the
+** case, this function fails with SQLITE_SCHEMA. If the input changeset
+** appears to be corrupt and the corruption is detected, SQLITE_CORRUPT is
+** returned. Or, if an out-of-memory condition occurs during processing, this
+** function returns SQLITE_NOMEM. In all cases, if an error occurs the
+** final contents of the changegroup is undefined.
+**
+** If no error occurs, SQLITE_OK is returned.
+*/
+int sqlite3changegroup_add(sqlite3_changegroup*, int nData, void *pData);
+
+/*
+** CAPI3REF: Obtain A Composite Changeset From A Changegroup
+**
+** Obtain a buffer containing a changeset (or patchset) representing the
+** current contents of the changegroup. If the inputs to the changegroup
+** were themselves changesets, the output is a changeset. Or, if the
+** inputs were patchsets, the output is also a patchset.
+**
+** As with the output of the sqlite3session_changeset() and
+** sqlite3session_patchset() functions, all changes related to a single
+** table are grouped together in the output of this function. Tables appear
+** in the same order as for the very first changeset added to the changegroup.
+** If the second or subsequent changesets added to the changegroup contain
+** changes for tables that do not appear in the first changeset, they are
+** appended onto the end of the output changeset, again in the order in
+** which they are first encountered.
+**
+** If an error occurs, an SQLite error code is returned and the output
+** variables (*pnData) and (*ppData) are set to 0. Otherwise, SQLITE_OK
+** is returned and the output variables are set to the size of and a 
+** pointer to the output buffer, respectively. In this case it is the
+** responsibility of the caller to eventually free the buffer using a
+** call to sqlite3_free().
+*/
+int sqlite3changegroup_output(
+  sqlite3_changegroup*,
+  int *pnData,                    /* OUT: Size of output buffer in bytes */
+  void **ppData                   /* OUT: Pointer to output buffer */
+);
+
+/*
+** CAPI3REF: Delete A Changegroup Object
+*/
+void sqlite3changegroup_delete(sqlite3_changegroup*);
+
+/*
+** CAPI3REF: Apply A Changeset To A Database
+**
+** Apply a changeset to a database. This function attempts to update the
+** "main" database attached to handle db with the changes found in the
+** changeset passed via the second and third arguments.
+**
+** The fourth argument (xFilter) passed to this function is the "filter
+** callback". If it is not NULL, then for each table affected by at least one
+** change in the changeset, the filter callback is invoked with
+** the table name as the second argument, and a copy of the context pointer
+** passed as the sixth argument to this function as the first. If the "filter
+** callback" returns zero, then no attempt is made to apply any changes to 
+** the table. Otherwise, if the return value is non-zero or the xFilter
+** argument to this function is NULL, all changes related to the table are
+** attempted.
+**
+** For each table that is not excluded by the filter callback, this function 
+** tests that the target database contains a compatible table. A table is 
+** considered compatible if all of the following are true:
+**
+** <ul>
+**   <li> The table has the same name as the name recorded in the 
+**        changeset, and
+**   <li> The table has the same number of columns as recorded in the 
+**        changeset, and
+**   <li> The table has primary key columns in the same position as 
+**        recorded in the changeset.
+** </ul>
+**
+** If there is no compatible table, it is not an error, but none of the
+** changes associated with the table are applied. A warning message is issued
+** via the sqlite3_log() mechanism with the error code SQLITE_SCHEMA. At most
+** one such warning is issued for each table in the changeset.
+**
+** For each change for which there is a compatible table, an attempt is made 
+** to modify the table contents according to the UPDATE, INSERT or DELETE 
+** change. If a change cannot be applied cleanly, the conflict handler 
+** function passed as the fifth argument to sqlite3changeset_apply() may be 
+** invoked. A description of exactly when the conflict handler is invoked for 
+** each type of change is below.
+**
+** Unlike the xFilter argument, xConflict may not be passed NULL. The results
+** of passing anything other than a valid function pointer as the xConflict
+** argument are undefined.
+**
+** Each time the conflict handler function is invoked, it must return one
+** of [SQLITE_CHANGESET_OMIT], [SQLITE_CHANGESET_ABORT] or 
+** [SQLITE_CHANGESET_REPLACE]. SQLITE_CHANGESET_REPLACE may only be returned
+** if the second argument passed to the conflict handler is either
+** SQLITE_CHANGESET_DATA or SQLITE_CHANGESET_CONFLICT. If the conflict-handler
+** returns an illegal value, any changes already made are rolled back and
+** the call to sqlite3changeset_apply() returns SQLITE_MISUSE. Different 
+** actions are taken by sqlite3changeset_apply() depending on the value
+** returned by each invocation of the conflict-handler function. Refer to
+** the documentation for the three 
+** [SQLITE_CHANGESET_OMIT|available return values] for details.
+**
+** <dl>
+** <dt>DELETE Changes<dd>
+**   For each DELETE change, this function checks if the target database 
+**   contains a row with the same primary key value (or values) as the 
+**   original row values stored in the changeset. If it does, and the values 
+**   stored in all non-primary key columns also match the values stored in 
+**   the changeset the row is deleted from the target database.
+**
+**   If a row with matching primary key values is found, but one or more of
+**   the non-primary key fields contains a value different from the original
+**   row value stored in the changeset, the conflict-handler function is
+**   invoked with [SQLITE_CHANGESET_DATA] as the second argument.
+**
+**   If no row with matching primary key values is found in the database,
+**   the conflict-handler function is invoked with [SQLITE_CHANGESET_NOTFOUND]
+**   passed as the second argument.
+**
+**   If the DELETE operation is attempted, but SQLite returns SQLITE_CONSTRAINT
+**   (which can only happen if a foreign key constraint is violated), the
+**   conflict-handler function is invoked with [SQLITE_CHANGESET_CONSTRAINT]
+**   passed as the second argument. This includes the case where the DELETE
+**   operation is attempted because an earlier call to the conflict handler
+**   function returned [SQLITE_CHANGESET_REPLACE].
+**
+** <dt>INSERT Changes<dd>
+**   For each INSERT change, an attempt is made to insert the new row into
+**   the database.
+**
+**   If the attempt to insert the row fails because the database already 
+**   contains a row with the same primary key values, the conflict handler
+**   function is invoked with the second argument set to 
+**   [SQLITE_CHANGESET_CONFLICT].
+**
+**   If the attempt to insert the row fails because of some other constraint
+**   violation (e.g. NOT NULL or UNIQUE), the conflict handler function is 
+**   invoked with the second argument set to [SQLITE_CHANGESET_CONSTRAINT].
+**   This includes the case where the INSERT operation is re-attempted because 
+**   an earlier call to the conflict handler function returned 
+**   [SQLITE_CHANGESET_REPLACE].
+**
+** <dt>UPDATE Changes<dd>
+**   For each UPDATE change, this function checks if the target database 
+**   contains a row with the same primary key value (or values) as the 
+**   original row values stored in the changeset. If it does, and the values 
+**   stored in all non-primary key columns also match the values stored in 
+**   the changeset the row is updated within the target database.
+**
+**   If a row with matching primary key values is found, but one or more of
+**   the non-primary key fields contains a value different from an original
+**   row value stored in the changeset, the conflict-handler function is
+**   invoked with [SQLITE_CHANGESET_DATA] as the second argument. Since
+**   UPDATE changes only contain values for non-primary key fields that are
+**   to be modified, only those fields need to match the original values to
+**   avoid the SQLITE_CHANGESET_DATA conflict-handler callback.
+**
+**   If no row with matching primary key values is found in the database,
+**   the conflict-handler function is invoked with [SQLITE_CHANGESET_NOTFOUND]
+**   passed as the second argument.
+**
+**   If the UPDATE operation is attempted, but SQLite returns 
+**   SQLITE_CONSTRAINT, the conflict-handler function is invoked with 
+**   [SQLITE_CHANGESET_CONSTRAINT] passed as the second argument.
+**   This includes the case where the UPDATE operation is attempted after 
+**   an earlier call to the conflict handler function returned
+**   [SQLITE_CHANGESET_REPLACE].  
+** </dl>
+**
+** It is safe to execute SQL statements, including those that write to the
+** table that the callback related to, from within the xConflict callback.
+** This can be used to further customize the applications conflict
+** resolution strategy.
+**
+** All changes made by this function are enclosed in a savepoint transaction.
+** If any other error (aside from a constraint failure when attempting to
+** write to the target database) occurs, then the savepoint transaction is
+** rolled back, restoring the target database to its original state, and an 
+** SQLite error code returned.
+*/
+int sqlite3changeset_apply(
+  sqlite3 *db,                    /* Apply change to "main" db of this handle */
+  int nChangeset,                 /* Size of changeset in bytes */
+  void *pChangeset,               /* Changeset blob */
+  int(*xFilter)(
+    void *pCtx,                   /* Copy of sixth arg to _apply() */
+    const char *zTab              /* Table name */
+  ),
+  int(*xConflict)(
+    void *pCtx,                   /* Copy of sixth arg to _apply() */
+    int eConflict,                /* DATA, MISSING, CONFLICT, CONSTRAINT */
+    sqlite3_changeset_iter *p     /* Handle describing change and conflict */
+  ),
+  void *pCtx                      /* First argument passed to xConflict */
+);
+
+/* 
+** CAPI3REF: Constants Passed To The Conflict Handler
+**
+** Values that may be passed as the second argument to a conflict-handler.
+**
+** <dl>
+** <dt>SQLITE_CHANGESET_DATA<dd>
+**   The conflict handler is invoked with CHANGESET_DATA as the second argument
+**   when processing a DELETE or UPDATE change if a row with the required
+**   PRIMARY KEY fields is present in the database, but one or more other 
+**   (non primary-key) fields modified by the update do not contain the 
+**   expected "before" values.
+** 
+**   The conflicting row, in this case, is the database row with the matching
+**   primary key.
+** 
+** <dt>SQLITE_CHANGESET_NOTFOUND<dd>
+**   The conflict handler is invoked with CHANGESET_NOTFOUND as the second
+**   argument when processing a DELETE or UPDATE change if a row with the
+**   required PRIMARY KEY fields is not present in the database.
+** 
+**   There is no conflicting row in this case. The results of invoking the
+**   sqlite3changeset_conflict() API are undefined.
+** 
+** <dt>SQLITE_CHANGESET_CONFLICT<dd>
+**   CHANGESET_CONFLICT is passed as the second argument to the conflict
+**   handler while processing an INSERT change if the operation would result 
+**   in duplicate primary key values.
+** 
+**   The conflicting row in this case is the database row with the matching
+**   primary key.
+**
+** <dt>SQLITE_CHANGESET_FOREIGN_KEY<dd>
+**   If foreign key handling is enabled, and applying a changeset leaves the
+**   database in a state containing foreign key violations, the conflict 
+**   handler is invoked with CHANGESET_FOREIGN_KEY as the second argument
+**   exactly once before the changeset is committed. If the conflict handler
+**   returns CHANGESET_OMIT, the changes, including those that caused the
+**   foreign key constraint violation, are committed. Or, if it returns
+**   CHANGESET_ABORT, the changeset is rolled back.
+**
+**   No current or conflicting row information is provided. The only function
+**   it is possible to call on the supplied sqlite3_changeset_iter handle
+**   is sqlite3changeset_fk_conflicts().
+** 
+** <dt>SQLITE_CHANGESET_CONSTRAINT<dd>
+**   If any other constraint violation occurs while applying a change (i.e. 
+**   a UNIQUE, CHECK or NOT NULL constraint), the conflict handler is 
+**   invoked with CHANGESET_CONSTRAINT as the second argument.
+** 
+**   There is no conflicting row in this case. The results of invoking the
+**   sqlite3changeset_conflict() API are undefined.
+**
+** </dl>
+*/
+#define SQLITE_CHANGESET_DATA        1
+#define SQLITE_CHANGESET_NOTFOUND    2
+#define SQLITE_CHANGESET_CONFLICT    3
+#define SQLITE_CHANGESET_CONSTRAINT  4
+#define SQLITE_CHANGESET_FOREIGN_KEY 5
+
+/* 
+** CAPI3REF: Constants Returned By The Conflict Handler
+**
+** A conflict handler callback must return one of the following three values.
+**
+** <dl>
+** <dt>SQLITE_CHANGESET_OMIT<dd>
+**   If a conflict handler returns this value no special action is taken. The
+**   change that caused the conflict is not applied. The session module 
+**   continues to the next change in the changeset.
+**
+** <dt>SQLITE_CHANGESET_REPLACE<dd>
+**   This value may only be returned if the second argument to the conflict
+**   handler was SQLITE_CHANGESET_DATA or SQLITE_CHANGESET_CONFLICT. If this
+**   is not the case, any changes applied so far are rolled back and the 
+**   call to sqlite3changeset_apply() returns SQLITE_MISUSE.
+**
+**   If CHANGESET_REPLACE is returned by an SQLITE_CHANGESET_DATA conflict
+**   handler, then the conflicting row is either updated or deleted, depending
+**   on the type of change.
+**
+**   If CHANGESET_REPLACE is returned by an SQLITE_CHANGESET_CONFLICT conflict
+**   handler, then the conflicting row is removed from the database and a
+**   second attempt to apply the change is made. If this second attempt fails,
+**   the original row is restored to the database before continuing.
+**
+** <dt>SQLITE_CHANGESET_ABORT<dd>
+**   If this value is returned, any changes applied so far are rolled back 
+**   and the call to sqlite3changeset_apply() returns SQLITE_ABORT.
+** </dl>
+*/
+#define SQLITE_CHANGESET_OMIT       0
+#define SQLITE_CHANGESET_REPLACE    1
+#define SQLITE_CHANGESET_ABORT      2
+
+/*
+** CAPI3REF: Streaming Versions of API functions.
+**
+** The six streaming API xxx_strm() functions serve similar purposes to the 
+** corresponding non-streaming API functions:
+**
+** <table border=1 style="margin-left:8ex;margin-right:8ex">
+**   <tr><th>Streaming function<th>Non-streaming equivalent</th>
+**   <tr><td>sqlite3changeset_apply_str<td>[sqlite3changeset_apply] 
+**   <tr><td>sqlite3changeset_concat_str<td>[sqlite3changeset_concat] 
+**   <tr><td>sqlite3changeset_invert_str<td>[sqlite3changeset_invert] 
+**   <tr><td>sqlite3changeset_start_str<td>[sqlite3changeset_start] 
+**   <tr><td>sqlite3session_changeset_str<td>[sqlite3session_changeset] 
+**   <tr><td>sqlite3session_patchset_str<td>[sqlite3session_patchset] 
+** </table>
+**
+** Non-streaming functions that accept changesets (or patchsets) as input
+** require that the entire changeset be stored in a single buffer in memory. 
+** Similarly, those that return a changeset or patchset do so by returning 
+** a pointer to a single large buffer allocated using sqlite3_malloc(). 
+** Normally this is convenient. However, if an application running in a 
+** low-memory environment is required to handle very large changesets, the
+** large contiguous memory allocations required can become onerous.
+**
+** In order to avoid this problem, instead of a single large buffer, input
+** is passed to a streaming API functions by way of a callback function that
+** the sessions module invokes to incrementally request input data as it is
+** required. In all cases, a pair of API function parameters such as
+**
+**  <pre>
+**  &nbsp;     int nChangeset,
+**  &nbsp;     void *pChangeset,
+**  </pre>
+**
+** Is replaced by:
+**
+**  <pre>
+**  &nbsp;     int (*xInput)(void *pIn, void *pData, int *pnData),
+**  &nbsp;     void *pIn,
+**  </pre>
+**
+** Each time the xInput callback is invoked by the sessions module, the first
+** argument passed is a copy of the supplied pIn context pointer. The second 
+** argument, pData, points to a buffer (*pnData) bytes in size. Assuming no 
+** error occurs the xInput method should copy up to (*pnData) bytes of data 
+** into the buffer and set (*pnData) to the actual number of bytes copied 
+** before returning SQLITE_OK. If the input is completely exhausted, (*pnData) 
+** should be set to zero to indicate this. Or, if an error occurs, an SQLite 
+** error code should be returned. In all cases, if an xInput callback returns
+** an error, all processing is abandoned and the streaming API function
+** returns a copy of the error code to the caller.
+**
+** In the case of sqlite3changeset_start_strm(), the xInput callback may be
+** invoked by the sessions module at any point during the lifetime of the
+** iterator. If such an xInput callback returns an error, the iterator enters
+** an error state, whereby all subsequent calls to iterator functions 
+** immediately fail with the same error code as returned by xInput.
+**
+** Similarly, streaming API functions that return changesets (or patchsets)
+** return them in chunks by way of a callback function instead of via a
+** pointer to a single large buffer. In this case, a pair of parameters such
+** as:
+**
+**  <pre>
+**  &nbsp;     int *pnChangeset,
+**  &nbsp;     void **ppChangeset,
+**  </pre>
+**
+** Is replaced by:
+**
+**  <pre>
+**  &nbsp;     int (*xOutput)(void *pOut, const void *pData, int nData),
+**  &nbsp;     void *pOut
+**  </pre>
+**
+** The xOutput callback is invoked zero or more times to return data to
+** the application. The first parameter passed to each call is a copy of the
+** pOut pointer supplied by the application. The second parameter, pData,
+** points to a buffer nData bytes in size containing the chunk of output
+** data being returned. If the xOutput callback successfully processes the
+** supplied data, it should return SQLITE_OK to indicate success. Otherwise,
+** it should return some other SQLite error code. In this case processing
+** is immediately abandoned and the streaming API function returns a copy
+** of the xOutput error code to the application.
+**
+** The sessions module never invokes an xOutput callback with the third 
+** parameter set to a value less than or equal to zero. Other than this,
+** no guarantees are made as to the size of the chunks of data returned.
+*/
+int sqlite3changeset_apply_strm(
+  sqlite3 *db,                    /* Apply change to "main" db of this handle */
+  int (*xInput)(void *pIn, void *pData, int *pnData), /* Input function */
+  void *pIn,                                          /* First arg for xInput */
+  int(*xFilter)(
+    void *pCtx,                   /* Copy of sixth arg to _apply() */
+    const char *zTab              /* Table name */
+  ),
+  int(*xConflict)(
+    void *pCtx,                   /* Copy of sixth arg to _apply() */
+    int eConflict,                /* DATA, MISSING, CONFLICT, CONSTRAINT */
+    sqlite3_changeset_iter *p     /* Handle describing change and conflict */
+  ),
+  void *pCtx                      /* First argument passed to xConflict */
+);
+int sqlite3changeset_concat_strm(
+  int (*xInputA)(void *pIn, void *pData, int *pnData),
+  void *pInA,
+  int (*xInputB)(void *pIn, void *pData, int *pnData),
+  void *pInB,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut
+);
+int sqlite3changeset_invert_strm(
+  int (*xInput)(void *pIn, void *pData, int *pnData),
+  void *pIn,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut
+);
+int sqlite3changeset_start_strm(
+  sqlite3_changeset_iter **pp,
+  int (*xInput)(void *pIn, void *pData, int *pnData),
+  void *pIn
+);
+int sqlite3session_changeset_strm(
+  sqlite3_session *pSession,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut
+);
+int sqlite3session_patchset_strm(
+  sqlite3_session *pSession,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut
+);
+int sqlite3changegroup_add_strm(sqlite3_changegroup*, 
+    int (*xInput)(void *pIn, void *pData, int *pnData),
+    void *pIn
+);
+int sqlite3changegroup_output_strm(sqlite3_changegroup*,
+    int (*xOutput)(void *pOut, const void *pData, int nData), 
+    void *pOut
+);
+
+
+/*
+** Make sure we can call this stuff from C++.
+*/
+#if 0
+}
+#endif
+
+#endif  /* !defined(__SQLITESESSION_H_) && defined(SQLITE_ENABLE_SESSION) */
+
+/******** End of sqlite3session.h *********/
+/******** Begin file fts5.h *********/
+/*
+** 2014 May 31
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** Interfaces to extend FTS5. Using the interfaces defined in this file, 
+** FTS5 may be extended with:
+**
+**     * custom tokenizers, and
+**     * custom auxiliary functions.
+*/
+
+
+#ifndef _FTS5_H
+#define _FTS5_H
+
+
+#if 0
+extern "C" {
+#endif
+
+/*************************************************************************
+** CUSTOM AUXILIARY FUNCTIONS
+**
+** Virtual table implementations may overload SQL functions by implementing
+** the sqlite3_module.xFindFunction() method.
+*/
+
+typedef struct Fts5ExtensionApi Fts5ExtensionApi;
+typedef struct Fts5Context Fts5Context;
+typedef struct Fts5PhraseIter Fts5PhraseIter;
+
+typedef void (*fts5_extension_function)(
+  const Fts5ExtensionApi *pApi,   /* API offered by current FTS version */
+  Fts5Context *pFts,              /* First arg to pass to pApi functions */
+  sqlite3_context *pCtx,          /* Context for returning result/error */
+  int nVal,                       /* Number of values in apVal[] array */
+  sqlite3_value **apVal           /* Array of trailing arguments */
+);
+
+struct Fts5PhraseIter {
+  const unsigned char *a;
+  const unsigned char *b;
+};
+
+/*
+** EXTENSION API FUNCTIONS
+**
+** xUserData(pFts):
+**   Return a copy of the context pointer the extension function was 
+**   registered with.
+**
+** xColumnTotalSize(pFts, iCol, pnToken):
+**   If parameter iCol is less than zero, set output variable *pnToken
+**   to the total number of tokens in the FTS5 table. Or, if iCol is
+**   non-negative but less than the number of columns in the table, return
+**   the total number of tokens in column iCol, considering all rows in 
+**   the FTS5 table.
+**
+**   If parameter iCol is greater than or equal to the number of columns
+**   in the table, SQLITE_RANGE is returned. Or, if an error occurs (e.g.
+**   an OOM condition or IO error), an appropriate SQLite error code is 
+**   returned.
+**
+** xColumnCount(pFts):
+**   Return the number of columns in the table.
+**
+** xColumnSize(pFts, iCol, pnToken):
+**   If parameter iCol is less than zero, set output variable *pnToken
+**   to the total number of tokens in the current row. Or, if iCol is
+**   non-negative but less than the number of columns in the table, set
+**   *pnToken to the number of tokens in column iCol of the current row.
+**
+**   If parameter iCol is greater than or equal to the number of columns
+**   in the table, SQLITE_RANGE is returned. Or, if an error occurs (e.g.
+**   an OOM condition or IO error), an appropriate SQLite error code is 
+**   returned.
+**
+**   This function may be quite inefficient if used with an FTS5 table
+**   created with the "columnsize=0" option.
+**
+** xColumnText:
+**   This function attempts to retrieve the text of column iCol of the
+**   current document. If successful, (*pz) is set to point to a buffer
+**   containing the text in utf-8 encoding, (*pn) is set to the size in bytes
+**   (not characters) of the buffer and SQLITE_OK is returned. Otherwise,
+**   if an error occurs, an SQLite error code is returned and the final values
+**   of (*pz) and (*pn) are undefined.
+**
+** xPhraseCount:
+**   Returns the number of phrases in the current query expression.
+**
+** xPhraseSize:
+**   Returns the number of tokens in phrase iPhrase of the query. Phrases
+**   are numbered starting from zero.
+**
+** xInstCount:
+**   Set *pnInst to the total number of occurrences of all phrases within
+**   the query within the current row. Return SQLITE_OK if successful, or
+**   an error code (i.e. SQLITE_NOMEM) if an error occurs.
+**
+**   This API can be quite slow if used with an FTS5 table created with the
+**   "detail=none" or "detail=column" option. If the FTS5 table is created 
+**   with either "detail=none" or "detail=column" and "content=" option 
+**   (i.e. if it is a contentless table), then this API always returns 0.
+**
+** xInst:
+**   Query for the details of phrase match iIdx within the current row.
+**   Phrase matches are numbered starting from zero, so the iIdx argument
+**   should be greater than or equal to zero and smaller than the value
+**   output by xInstCount().
+**
+**   Usually, output parameter *piPhrase is set to the phrase number, *piCol
+**   to the column in which it occurs and *piOff the token offset of the
+**   first token of the phrase. The exception is if the table was created
+**   with the offsets=0 option specified. In this case *piOff is always
+**   set to -1.
+**
+**   Returns SQLITE_OK if successful, or an error code (i.e. SQLITE_NOMEM) 
+**   if an error occurs.
+**
+**   This API can be quite slow if used with an FTS5 table created with the
+**   "detail=none" or "detail=column" option. 
+**
+** xRowid:
+**   Returns the rowid of the current row.
+**
+** xTokenize:
+**   Tokenize text using the tokenizer belonging to the FTS5 table.
+**
+** xQueryPhrase(pFts5, iPhrase, pUserData, xCallback):
+**   This API function is used to query the FTS table for phrase iPhrase
+**   of the current query. Specifically, a query equivalent to:
+**
+**       ... FROM ftstable WHERE ftstable MATCH $p ORDER BY rowid
+**
+**   with $p set to a phrase equivalent to the phrase iPhrase of the
+**   current query is executed. Any column filter that applies to
+**   phrase iPhrase of the current query is included in $p. For each 
+**   row visited, the callback function passed as the fourth argument 
+**   is invoked. The context and API objects passed to the callback 
+**   function may be used to access the properties of each matched row.
+**   Invoking Api.xUserData() returns a copy of the pointer passed as 
+**   the third argument to pUserData.
+**
+**   If the callback function returns any value other than SQLITE_OK, the
+**   query is abandoned and the xQueryPhrase function returns immediately.
+**   If the returned value is SQLITE_DONE, xQueryPhrase returns SQLITE_OK.
+**   Otherwise, the error code is propagated upwards.
+**
+**   If the query runs to completion without incident, SQLITE_OK is returned.
+**   Or, if some error occurs before the query completes or is aborted by
+**   the callback, an SQLite error code is returned.
+**
+**
+** xSetAuxdata(pFts5, pAux, xDelete)
+**
+**   Save the pointer passed as the second argument as the extension functions 
+**   "auxiliary data". The pointer may then be retrieved by the current or any
+**   future invocation of the same fts5 extension function made as part of
+**   of the same MATCH query using the xGetAuxdata() API.
+**
+**   Each extension function is allocated a single auxiliary data slot for
+**   each FTS query (MATCH expression). If the extension function is invoked 
+**   more than once for a single FTS query, then all invocations share a 
+**   single auxiliary data context.
+**
+**   If there is already an auxiliary data pointer when this function is
+**   invoked, then it is replaced by the new pointer. If an xDelete callback
+**   was specified along with the original pointer, it is invoked at this
+**   point.
+**
+**   The xDelete callback, if one is specified, is also invoked on the
+**   auxiliary data pointer after the FTS5 query has finished.
+**
+**   If an error (e.g. an OOM condition) occurs within this function, an
+**   the auxiliary data is set to NULL and an error code returned. If the
+**   xDelete parameter was not NULL, it is invoked on the auxiliary data
+**   pointer before returning.
+**
+**
+** xGetAuxdata(pFts5, bClear)
+**
+**   Returns the current auxiliary data pointer for the fts5 extension 
+**   function. See the xSetAuxdata() method for details.
+**
+**   If the bClear argument is non-zero, then the auxiliary data is cleared
+**   (set to NULL) before this function returns. In this case the xDelete,
+**   if any, is not invoked.
+**
+**
+** xRowCount(pFts5, pnRow)
+**
+**   This function is used to retrieve the total number of rows in the table.
+**   In other words, the same value that would be returned by:
+**
+**        SELECT count(*) FROM ftstable;
+**
+** xPhraseFirst()
+**   This function is used, along with type Fts5PhraseIter and the xPhraseNext
+**   method, to iterate through all instances of a single query phrase within
+**   the current row. This is the same information as is accessible via the
+**   xInstCount/xInst APIs. While the xInstCount/xInst APIs are more convenient
+**   to use, this API may be faster under some circumstances. To iterate 
+**   through instances of phrase iPhrase, use the following code:
+**
+**       Fts5PhraseIter iter;
+**       int iCol, iOff;
+**       for(pApi->xPhraseFirst(pFts, iPhrase, &iter, &iCol, &iOff);
+**           iCol>=0;
+**           pApi->xPhraseNext(pFts, &iter, &iCol, &iOff)
+**       ){
+**         // An instance of phrase iPhrase at offset iOff of column iCol
+**       }
+**
+**   The Fts5PhraseIter structure is defined above. Applications should not
+**   modify this structure directly - it should only be used as shown above
+**   with the xPhraseFirst() and xPhraseNext() API methods (and by
+**   xPhraseFirstColumn() and xPhraseNextColumn() as illustrated below).
+**
+**   This API can be quite slow if used with an FTS5 table created with the
+**   "detail=none" or "detail=column" option. If the FTS5 table is created 
+**   with either "detail=none" or "detail=column" and "content=" option 
+**   (i.e. if it is a contentless table), then this API always iterates
+**   through an empty set (all calls to xPhraseFirst() set iCol to -1).
+**
+** xPhraseNext()
+**   See xPhraseFirst above.
+**
+** xPhraseFirstColumn()
+**   This function and xPhraseNextColumn() are similar to the xPhraseFirst()
+**   and xPhraseNext() APIs described above. The difference is that instead
+**   of iterating through all instances of a phrase in the current row, these
+**   APIs are used to iterate through the set of columns in the current row
+**   that contain one or more instances of a specified phrase. For example:
+**
+**       Fts5PhraseIter iter;
+**       int iCol;
+**       for(pApi->xPhraseFirstColumn(pFts, iPhrase, &iter, &iCol);
+**           iCol>=0;
+**           pApi->xPhraseNextColumn(pFts, &iter, &iCol)
+**       ){
+**         // Column iCol contains at least one instance of phrase iPhrase
+**       }
+**
+**   This API can be quite slow if used with an FTS5 table created with the
+**   "detail=none" option. If the FTS5 table is created with either 
+**   "detail=none" "content=" option (i.e. if it is a contentless table), 
+**   then this API always iterates through an empty set (all calls to 
+**   xPhraseFirstColumn() set iCol to -1).
+**
+**   The information accessed using this API and its companion
+**   xPhraseFirstColumn() may also be obtained using xPhraseFirst/xPhraseNext
+**   (or xInst/xInstCount). The chief advantage of this API is that it is
+**   significantly more efficient than those alternatives when used with
+**   "detail=column" tables.  
+**
+** xPhraseNextColumn()
+**   See xPhraseFirstColumn above.
+*/
+struct Fts5ExtensionApi {
+  int iVersion;                   /* Currently always set to 3 */
+
+  void *(*xUserData)(Fts5Context*);
+
+  int (*xColumnCount)(Fts5Context*);
+  int (*xRowCount)(Fts5Context*, sqlite3_int64 *pnRow);
+  int (*xColumnTotalSize)(Fts5Context*, int iCol, sqlite3_int64 *pnToken);
+
+  int (*xTokenize)(Fts5Context*, 
+    const char *pText, int nText, /* Text to tokenize */
+    void *pCtx,                   /* Context passed to xToken() */
+    int (*xToken)(void*, int, const char*, int, int, int)       /* Callback */
+  );
+
+  int (*xPhraseCount)(Fts5Context*);
+  int (*xPhraseSize)(Fts5Context*, int iPhrase);
+
+  int (*xInstCount)(Fts5Context*, int *pnInst);
+  int (*xInst)(Fts5Context*, int iIdx, int *piPhrase, int *piCol, int *piOff);
+
+  sqlite3_int64 (*xRowid)(Fts5Context*);
+  int (*xColumnText)(Fts5Context*, int iCol, const char **pz, int *pn);
+  int (*xColumnSize)(Fts5Context*, int iCol, int *pnToken);
+
+  int (*xQueryPhrase)(Fts5Context*, int iPhrase, void *pUserData,
+    int(*)(const Fts5ExtensionApi*,Fts5Context*,void*)
+  );
+  int (*xSetAuxdata)(Fts5Context*, void *pAux, void(*xDelete)(void*));
+  void *(*xGetAuxdata)(Fts5Context*, int bClear);
+
+  int (*xPhraseFirst)(Fts5Context*, int iPhrase, Fts5PhraseIter*, int*, int*);
+  void (*xPhraseNext)(Fts5Context*, Fts5PhraseIter*, int *piCol, int *piOff);
+
+  int (*xPhraseFirstColumn)(Fts5Context*, int iPhrase, Fts5PhraseIter*, int*);
+  void (*xPhraseNextColumn)(Fts5Context*, Fts5PhraseIter*, int *piCol);
+};
+
+/* 
+** CUSTOM AUXILIARY FUNCTIONS
+*************************************************************************/
+
+/*************************************************************************
+** CUSTOM TOKENIZERS
+**
+** Applications may also register custom tokenizer types. A tokenizer 
+** is registered by providing fts5 with a populated instance of the 
+** following structure. All structure methods must be defined, setting
+** any member of the fts5_tokenizer struct to NULL leads to undefined
+** behaviour. The structure methods are expected to function as follows:
+**
+** xCreate:
+**   This function is used to allocate and initialize a tokenizer instance.
+**   A tokenizer instance is required to actually tokenize text.
+**
+**   The first argument passed to this function is a copy of the (void*)
+**   pointer provided by the application when the fts5_tokenizer object
+**   was registered with FTS5 (the third argument to xCreateTokenizer()). 
+**   The second and third arguments are an array of nul-terminated strings
+**   containing the tokenizer arguments, if any, specified following the
+**   tokenizer name as part of the CREATE VIRTUAL TABLE statement used
+**   to create the FTS5 table.
+**
+**   The final argument is an output variable. If successful, (*ppOut) 
+**   should be set to point to the new tokenizer handle and SQLITE_OK
+**   returned. If an error occurs, some value other than SQLITE_OK should
+**   be returned. In this case, fts5 assumes that the final value of *ppOut 
+**   is undefined.
+**
+** xDelete:
+**   This function is invoked to delete a tokenizer handle previously
+**   allocated using xCreate(). Fts5 guarantees that this function will
+**   be invoked exactly once for each successful call to xCreate().
+**
+** xTokenize:
+**   This function is expected to tokenize the nText byte string indicated 
+**   by argument pText. pText may or may not be nul-terminated. The first
+**   argument passed to this function is a pointer to an Fts5Tokenizer object
+**   returned by an earlier call to xCreate().
+**
+**   The second argument indicates the reason that FTS5 is requesting
+**   tokenization of the supplied text. This is always one of the following
+**   four values:
+**
+**   <ul><li> <b>FTS5_TOKENIZE_DOCUMENT</b> - A document is being inserted into
+**            or removed from the FTS table. The tokenizer is being invoked to
+**            determine the set of tokens to add to (or delete from) the
+**            FTS index.
+**
+**       <li> <b>FTS5_TOKENIZE_QUERY</b> - A MATCH query is being executed 
+**            against the FTS index. The tokenizer is being called to tokenize 
+**            a bareword or quoted string specified as part of the query.
+**
+**       <li> <b>(FTS5_TOKENIZE_QUERY | FTS5_TOKENIZE_PREFIX)</b> - Same as
+**            FTS5_TOKENIZE_QUERY, except that the bareword or quoted string is
+**            followed by a "*" character, indicating that the last token
+**            returned by the tokenizer will be treated as a token prefix.
+**
+**       <li> <b>FTS5_TOKENIZE_AUX</b> - The tokenizer is being invoked to 
+**            satisfy an fts5_api.xTokenize() request made by an auxiliary
+**            function. Or an fts5_api.xColumnSize() request made by the same
+**            on a columnsize=0 database.  
+**   </ul>
+**
+**   For each token in the input string, the supplied callback xToken() must
+**   be invoked. The first argument to it should be a copy of the pointer
+**   passed as the second argument to xTokenize(). The third and fourth
+**   arguments are a pointer to a buffer containing the token text, and the
+**   size of the token in bytes. The 4th and 5th arguments are the byte offsets
+**   of the first byte of and first byte immediately following the text from
+**   which the token is derived within the input.
+**
+**   The second argument passed to the xToken() callback ("tflags") should
+**   normally be set to 0. The exception is if the tokenizer supports 
+**   synonyms. In this case see the discussion below for details.
+**
+**   FTS5 assumes the xToken() callback is invoked for each token in the 
+**   order that they occur within the input text.
+**
+**   If an xToken() callback returns any value other than SQLITE_OK, then
+**   the tokenization should be abandoned and the xTokenize() method should
+**   immediately return a copy of the xToken() return value. Or, if the
+**   input buffer is exhausted, xTokenize() should return SQLITE_OK. Finally,
+**   if an error occurs with the xTokenize() implementation itself, it
+**   may abandon the tokenization and return any error code other than
+**   SQLITE_OK or SQLITE_DONE.
+**
+** SYNONYM SUPPORT
+**
+**   Custom tokenizers may also support synonyms. Consider a case in which a
+**   user wishes to query for a phrase such as "first place". Using the 
+**   built-in tokenizers, the FTS5 query 'first + place' will match instances
+**   of "first place" within the document set, but not alternative forms
+**   such as "1st place". In some applications, it would be better to match
+**   all instances of "first place" or "1st place" regardless of which form
+**   the user specified in the MATCH query text.
+**
+**   There are several ways to approach this in FTS5:
+**
+**   <ol><li> By mapping all synonyms to a single token. In this case, the 
+**            In the above example, this means that the tokenizer returns the
+**            same token for inputs "first" and "1st". Say that token is in
+**            fact "first", so that when the user inserts the document "I won
+**            1st place" entries are added to the index for tokens "i", "won",
+**            "first" and "place". If the user then queries for '1st + place',
+**            the tokenizer substitutes "first" for "1st" and the query works
+**            as expected.
+**
+**       <li> By adding multiple synonyms for a single term to the FTS index.
+**            In this case, when tokenizing query text, the tokenizer may 
+**            provide multiple synonyms for a single term within the document.
+**            FTS5 then queries the index for each synonym individually. For
+**            example, faced with the query:
+**
+**   <codeblock>
+**     ... MATCH 'first place'</codeblock>
+**
+**            the tokenizer offers both "1st" and "first" as synonyms for the
+**            first token in the MATCH query and FTS5 effectively runs a query 
+**            similar to:
+**
+**   <codeblock>
+**     ... MATCH '(first OR 1st) place'</codeblock>
+**
+**            except that, for the purposes of auxiliary functions, the query
+**            still appears to contain just two phrases - "(first OR 1st)" 
+**            being treated as a single phrase.
+**
+**       <li> By adding multiple synonyms for a single term to the FTS index.
+**            Using this method, when tokenizing document text, the tokenizer
+**            provides multiple synonyms for each token. So that when a 
+**            document such as "I won first place" is tokenized, entries are
+**            added to the FTS index for "i", "won", "first", "1st" and
+**            "place".
+**
+**            This way, even if the tokenizer does not provide synonyms
+**            when tokenizing query text (it should not - to do would be
+**            inefficient), it doesn't matter if the user queries for 
+**            'first + place' or '1st + place', as there are entires in the
+**            FTS index corresponding to both forms of the first token.
+**   </ol>
+**
+**   Whether it is parsing document or query text, any call to xToken that
+**   specifies a <i>tflags</i> argument with the FTS5_TOKEN_COLOCATED bit
+**   is considered to supply a synonym for the previous token. For example,
+**   when parsing the document "I won first place", a tokenizer that supports
+**   synonyms would call xToken() 5 times, as follows:
+**
+**   <codeblock>
+**       xToken(pCtx, 0, "i",                      1,  0,  1);
+**       xToken(pCtx, 0, "won",                    3,  2,  5);
+**       xToken(pCtx, 0, "first",                  5,  6, 11);
+**       xToken(pCtx, FTS5_TOKEN_COLOCATED, "1st", 3,  6, 11);
+**       xToken(pCtx, 0, "place",                  5, 12, 17);
+**</codeblock>
+**
+**   It is an error to specify the FTS5_TOKEN_COLOCATED flag the first time
+**   xToken() is called. Multiple synonyms may be specified for a single token
+**   by making multiple calls to xToken(FTS5_TOKEN_COLOCATED) in sequence. 
+**   There is no limit to the number of synonyms that may be provided for a
+**   single token.
+**
+**   In many cases, method (1) above is the best approach. It does not add 
+**   extra data to the FTS index or require FTS5 to query for multiple terms,
+**   so it is efficient in terms of disk space and query speed. However, it
+**   does not support prefix queries very well. If, as suggested above, the
+**   token "first" is subsituted for "1st" by the tokenizer, then the query:
+**
+**   <codeblock>
+**     ... MATCH '1s*'</codeblock>
+**
+**   will not match documents that contain the token "1st" (as the tokenizer
+**   will probably not map "1s" to any prefix of "first").
+**
+**   For full prefix support, method (3) may be preferred. In this case, 
+**   because the index contains entries for both "first" and "1st", prefix
+**   queries such as 'fi*' or '1s*' will match correctly. However, because
+**   extra entries are added to the FTS index, this method uses more space
+**   within the database.
+**
+**   Method (2) offers a midpoint between (1) and (3). Using this method,
+**   a query such as '1s*' will match documents that contain the literal 
+**   token "1st", but not "first" (assuming the tokenizer is not able to
+**   provide synonyms for prefixes). However, a non-prefix query like '1st'
+**   will match against "1st" and "first". This method does not require
+**   extra disk space, as no extra entries are added to the FTS index. 
+**   On the other hand, it may require more CPU cycles to run MATCH queries,
+**   as separate queries of the FTS index are required for each synonym.
+**
+**   When using methods (2) or (3), it is important that the tokenizer only
+**   provide synonyms when tokenizing document text (method (2)) or query
+**   text (method (3)), not both. Doing so will not cause any errors, but is
+**   inefficient.
+*/
+typedef struct Fts5Tokenizer Fts5Tokenizer;
+typedef struct fts5_tokenizer fts5_tokenizer;
+struct fts5_tokenizer {
+  int (*xCreate)(void*, const char **azArg, int nArg, Fts5Tokenizer **ppOut);
+  void (*xDelete)(Fts5Tokenizer*);
+  int (*xTokenize)(Fts5Tokenizer*, 
+      void *pCtx,
+      int flags,            /* Mask of FTS5_TOKENIZE_* flags */
+      const char *pText, int nText, 
+      int (*xToken)(
+        void *pCtx,         /* Copy of 2nd argument to xTokenize() */
+        int tflags,         /* Mask of FTS5_TOKEN_* flags */
+        const char *pToken, /* Pointer to buffer containing token */
+        int nToken,         /* Size of token in bytes */
+        int iStart,         /* Byte offset of token within input text */
+        int iEnd            /* Byte offset of end of token within input text */
+      )
+  );
+};
+
+/* Flags that may be passed as the third argument to xTokenize() */
+#define FTS5_TOKENIZE_QUERY     0x0001
+#define FTS5_TOKENIZE_PREFIX    0x0002
+#define FTS5_TOKENIZE_DOCUMENT  0x0004
+#define FTS5_TOKENIZE_AUX       0x0008
+
+/* Flags that may be passed by the tokenizer implementation back to FTS5
+** as the third argument to the supplied xToken callback. */
+#define FTS5_TOKEN_COLOCATED    0x0001      /* Same position as prev. token */
+
+/*
+** END OF CUSTOM TOKENIZERS
+*************************************************************************/
+
+/*************************************************************************
+** FTS5 EXTENSION REGISTRATION API
+*/
+typedef struct fts5_api fts5_api;
+struct fts5_api {
+  int iVersion;                   /* Currently always set to 2 */
+
+  /* Create a new tokenizer */
+  int (*xCreateTokenizer)(
+    fts5_api *pApi,
+    const char *zName,
+    void *pContext,
+    fts5_tokenizer *pTokenizer,
+    void (*xDestroy)(void*)
+  );
+
+  /* Find an existing tokenizer */
+  int (*xFindTokenizer)(
+    fts5_api *pApi,
+    const char *zName,
+    void **ppContext,
+    fts5_tokenizer *pTokenizer
+  );
+
+  /* Create a new auxiliary function */
+  int (*xCreateFunction)(
+    fts5_api *pApi,
+    const char *zName,
+    void *pContext,
+    fts5_extension_function xFunction,
+    void (*xDestroy)(void*)
+  );
+};
+
+/*
+** END OF REGISTRATION API
+*************************************************************************/
+
+#if 0
+}  /* end of the 'extern "C"' block */
+#endif
+
+#endif /* _FTS5_H */
+
+/******** End of fts5.h *********/
+
+/************** End of sqlite3.h *********************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+
+/*
+** Include the configuration header output by 'configure' if we're using the
+** autoconf-based build
+*/
+#ifdef _HAVE_SQLITE_CONFIG_H
+#include "config.h"
+#endif
+
+/************** Include sqliteLimit.h in the middle of sqliteInt.h ***********/
+/************** Begin file sqliteLimit.h *************************************/
+/*
+** 2007 May 7
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** 
+** This file defines various limits of what SQLite can process.
+*/
+
+/*
+** The maximum length of a TEXT or BLOB in bytes.   This also
+** limits the size of a row in a table or index.
+**
+** The hard limit is the ability of a 32-bit signed integer
+** to count the size: 2^31-1 or 2147483647.
+*/
+#ifndef SQLITE_MAX_LENGTH
+# define SQLITE_MAX_LENGTH 1000000000
+#endif
+
+/*
+** This is the maximum number of
+**
+**    * Columns in a table
+**    * Columns in an index
+**    * Columns in a view
+**    * Terms in the SET clause of an UPDATE statement
+**    * Terms in the result set of a SELECT statement
+**    * Terms in the GROUP BY or ORDER BY clauses of a SELECT statement.
+**    * Terms in the VALUES clause of an INSERT statement
+**
+** The hard upper limit here is 32676.  Most database people will
+** tell you that in a well-normalized database, you usually should
+** not have more than a dozen or so columns in any table.  And if
+** that is the case, there is no point in having more than a few
+** dozen values in any of the other situations described above.
+*/
+#ifndef SQLITE_MAX_COLUMN
+# define SQLITE_MAX_COLUMN 2000
+#endif
+
+/*
+** The maximum length of a single SQL statement in bytes.
+**
+** It used to be the case that setting this value to zero would
+** turn the limit off.  That is no longer true.  It is not possible
+** to turn this limit off.
+*/
+#ifndef SQLITE_MAX_SQL_LENGTH
+# define SQLITE_MAX_SQL_LENGTH 1000000000
+#endif
+
+/*
+** The maximum depth of an expression tree. This is limited to 
+** some extent by SQLITE_MAX_SQL_LENGTH. But sometime you might 
+** want to place more severe limits on the complexity of an 
+** expression.
+**
+** A value of 0 used to mean that the limit was not enforced.
+** But that is no longer true.  The limit is now strictly enforced
+** at all times.
+*/
+#ifndef SQLITE_MAX_EXPR_DEPTH
+# define SQLITE_MAX_EXPR_DEPTH 1000
+#endif
+
+/*
+** The maximum number of terms in a compound SELECT statement.
+** The code generator for compound SELECT statements does one
+** level of recursion for each term.  A stack overflow can result
+** if the number of terms is too large.  In practice, most SQL
+** never has more than 3 or 4 terms.  Use a value of 0 to disable
+** any limit on the number of terms in a compount SELECT.
+*/
+#ifndef SQLITE_MAX_COMPOUND_SELECT
+# define SQLITE_MAX_COMPOUND_SELECT 500
+#endif
+
+/*
+** The maximum number of opcodes in a VDBE program.
+** Not currently enforced.
+*/
+#ifndef SQLITE_MAX_VDBE_OP
+# define SQLITE_MAX_VDBE_OP 25000
+#endif
+
+/*
+** The maximum number of arguments to an SQL function.
+*/
+#ifndef SQLITE_MAX_FUNCTION_ARG
+# define SQLITE_MAX_FUNCTION_ARG 127
+#endif
+
+/*
+** The suggested maximum number of in-memory pages to use for
+** the main database table and for temporary tables.
+**
+** IMPLEMENTATION-OF: R-30185-15359 The default suggested cache size is -2000,
+** which means the cache size is limited to 2048000 bytes of memory.
+** IMPLEMENTATION-OF: R-48205-43578 The default suggested cache size can be
+** altered using the SQLITE_DEFAULT_CACHE_SIZE compile-time options.
+*/
+#ifndef SQLITE_DEFAULT_CACHE_SIZE
+# define SQLITE_DEFAULT_CACHE_SIZE  -2000
+#endif
+
+/*
+** The default number of frames to accumulate in the log file before
+** checkpointing the database in WAL mode.
+*/
+#ifndef SQLITE_DEFAULT_WAL_AUTOCHECKPOINT
+# define SQLITE_DEFAULT_WAL_AUTOCHECKPOINT  1000
+#endif
+
+/*
+** The maximum number of attached databases.  This must be between 0
+** and 125.  The upper bound of 125 is because the attached databases are
+** counted using a signed 8-bit integer which has a maximum value of 127
+** and we have to allow 2 extra counts for the "main" and "temp" databases.
+*/
+#ifndef SQLITE_MAX_ATTACHED
+# define SQLITE_MAX_ATTACHED 10
+#endif
+
+
+/*
+** The maximum value of a ?nnn wildcard that the parser will accept.
+*/
+#ifndef SQLITE_MAX_VARIABLE_NUMBER
+# define SQLITE_MAX_VARIABLE_NUMBER 999
+#endif
+
+/* Maximum page size.  The upper bound on this value is 65536.  This a limit
+** imposed by the use of 16-bit offsets within each page.
+**
+** Earlier versions of SQLite allowed the user to change this value at
+** compile time. This is no longer permitted, on the grounds that it creates
+** a library that is technically incompatible with an SQLite library 
+** compiled with a different limit. If a process operating on a database 
+** with a page-size of 65536 bytes crashes, then an instance of SQLite 
+** compiled with the default page-size limit will not be able to rollback 
+** the aborted transaction. This could lead to database corruption.
+*/
+#ifdef SQLITE_MAX_PAGE_SIZE
+# undef SQLITE_MAX_PAGE_SIZE
+#endif
+#define SQLITE_MAX_PAGE_SIZE 65536
+
+
+/*
+** The default size of a database page.
+*/
+#ifndef SQLITE_DEFAULT_PAGE_SIZE
+# define SQLITE_DEFAULT_PAGE_SIZE 4096
+#endif
+#if SQLITE_DEFAULT_PAGE_SIZE>SQLITE_MAX_PAGE_SIZE
+# undef SQLITE_DEFAULT_PAGE_SIZE
+# define SQLITE_DEFAULT_PAGE_SIZE SQLITE_MAX_PAGE_SIZE
+#endif
+
+/*
+** Ordinarily, if no value is explicitly provided, SQLite creates databases
+** with page size SQLITE_DEFAULT_PAGE_SIZE. However, based on certain
+** device characteristics (sector-size and atomic write() support),
+** SQLite may choose a larger value. This constant is the maximum value
+** SQLite will choose on its own.
+*/
+#ifndef SQLITE_MAX_DEFAULT_PAGE_SIZE
+# define SQLITE_MAX_DEFAULT_PAGE_SIZE 8192
+#endif
+#if SQLITE_MAX_DEFAULT_PAGE_SIZE>SQLITE_MAX_PAGE_SIZE
+# undef SQLITE_MAX_DEFAULT_PAGE_SIZE
+# define SQLITE_MAX_DEFAULT_PAGE_SIZE SQLITE_MAX_PAGE_SIZE
+#endif
+
+
+/*
+** Maximum number of pages in one database file.
+**
+** This is really just the default value for the max_page_count pragma.
+** This value can be lowered (or raised) at run-time using that the
+** max_page_count macro.
+*/
+#ifndef SQLITE_MAX_PAGE_COUNT
+# define SQLITE_MAX_PAGE_COUNT 1073741823
+#endif
+
+/*
+** Maximum length (in bytes) of the pattern in a LIKE or GLOB
+** operator.
+*/
+#ifndef SQLITE_MAX_LIKE_PATTERN_LENGTH
+# define SQLITE_MAX_LIKE_PATTERN_LENGTH 50000
+#endif
+
+/*
+** Maximum depth of recursion for triggers.
+**
+** A value of 1 means that a trigger program will not be able to itself
+** fire any triggers. A value of 0 means that no trigger programs at all 
+** may be executed.
+*/
+#ifndef SQLITE_MAX_TRIGGER_DEPTH
+# define SQLITE_MAX_TRIGGER_DEPTH 1000
+#endif
+
+/************** End of sqliteLimit.h *****************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+
+/* Disable nuisance warnings on Borland compilers */
+#if defined(__BORLANDC__)
+#pragma warn -rch /* unreachable code */
+#pragma warn -ccc /* Condition is always true or false */
+#pragma warn -aus /* Assigned value is never used */
+#pragma warn -csu /* Comparing signed and unsigned */
+#pragma warn -spa /* Suspicious pointer arithmetic */
+#endif
+
+/*
+** Include standard header files as necessary
+*/
+#ifdef HAVE_STDINT_H
+#include <stdint.h>
+#endif
+#ifdef HAVE_INTTYPES_H
+#include <inttypes.h>
+#endif
+
+/*
+** The following macros are used to cast pointers to integers and
+** integers to pointers.  The way you do this varies from one compiler
+** to the next, so we have developed the following set of #if statements
+** to generate appropriate macros for a wide range of compilers.
+**
+** The correct "ANSI" way to do this is to use the intptr_t type.
+** Unfortunately, that typedef is not available on all compilers, or
+** if it is available, it requires an #include of specific headers
+** that vary from one machine to the next.
+**
+** Ticket #3860:  The llvm-gcc-4.2 compiler from Apple chokes on
+** the ((void*)&((char*)0)[X]) construct.  But MSVC chokes on ((void*)(X)).
+** So we have to define the macros in different ways depending on the
+** compiler.
+*/
+#if defined(__PTRDIFF_TYPE__)  /* This case should work for GCC */
+# define SQLITE_INT_TO_PTR(X)  ((void*)(__PTRDIFF_TYPE__)(X))
+# define SQLITE_PTR_TO_INT(X)  ((int)(__PTRDIFF_TYPE__)(X))
+#elif !defined(__GNUC__)       /* Works for compilers other than LLVM */
+# define SQLITE_INT_TO_PTR(X)  ((void*)&((char*)0)[X])
+# define SQLITE_PTR_TO_INT(X)  ((int)(((char*)X)-(char*)0))
+#elif defined(HAVE_STDINT_H)   /* Use this case if we have ANSI headers */
+# define SQLITE_INT_TO_PTR(X)  ((void*)(intptr_t)(X))
+# define SQLITE_PTR_TO_INT(X)  ((int)(intptr_t)(X))
+#else                          /* Generates a warning - but it always works */
+# define SQLITE_INT_TO_PTR(X)  ((void*)(X))
+# define SQLITE_PTR_TO_INT(X)  ((int)(X))
+#endif
+
+/*
+** A macro to hint to the compiler that a function should not be
+** inlined.
+*/
+#if defined(__GNUC__)
+#  define SQLITE_NOINLINE  __attribute__((noinline))
+#elif defined(_MSC_VER) && _MSC_VER>=1310
+#  define SQLITE_NOINLINE  __declspec(noinline)
+#else
+#  define SQLITE_NOINLINE
+#endif
+
+/*
+** Make sure that the compiler intrinsics we desire are enabled when
+** compiling with an appropriate version of MSVC unless prevented by
+** the SQLITE_DISABLE_INTRINSIC define.
+*/
+#if !defined(SQLITE_DISABLE_INTRINSIC)
+#  if defined(_MSC_VER) && _MSC_VER>=1400
+#    if !defined(_WIN32_WCE)
+#      include <intrin.h>
+#      pragma intrinsic(_byteswap_ushort)
+#      pragma intrinsic(_byteswap_ulong)
+#      pragma intrinsic(_ReadWriteBarrier)
+#    else
+#      include <cmnintrin.h>
+#    endif
+#  endif
+#endif
+
+/*
+** The SQLITE_THREADSAFE macro must be defined as 0, 1, or 2.
+** 0 means mutexes are permanently disable and the library is never
+** threadsafe.  1 means the library is serialized which is the highest
+** level of threadsafety.  2 means the library is multithreaded - multiple
+** threads can use SQLite as long as no two threads try to use the same
+** database connection at the same time.
+**
+** Older versions of SQLite used an optional THREADSAFE macro.
+** We support that for legacy.
+*/
+#if !defined(SQLITE_THREADSAFE)
+# if defined(THREADSAFE)
+#   define SQLITE_THREADSAFE THREADSAFE
+# else
+#   define SQLITE_THREADSAFE 1 /* IMP: R-07272-22309 */
+# endif
+#endif
+
+/*
+** Powersafe overwrite is on by default.  But can be turned off using
+** the -DSQLITE_POWERSAFE_OVERWRITE=0 command-line option.
+*/
+#ifndef SQLITE_POWERSAFE_OVERWRITE
+# define SQLITE_POWERSAFE_OVERWRITE 1
+#endif
+
+/*
+** EVIDENCE-OF: R-25715-37072 Memory allocation statistics are enabled by
+** default unless SQLite is compiled with SQLITE_DEFAULT_MEMSTATUS=0 in
+** which case memory allocation statistics are disabled by default.
+*/
+#if !defined(SQLITE_DEFAULT_MEMSTATUS)
+# define SQLITE_DEFAULT_MEMSTATUS 1
+#endif
+
+/*
+** Exactly one of the following macros must be defined in order to
+** specify which memory allocation subsystem to use.
+**
+**     SQLITE_SYSTEM_MALLOC          // Use normal system malloc()
+**     SQLITE_WIN32_MALLOC           // Use Win32 native heap API
+**     SQLITE_ZERO_MALLOC            // Use a stub allocator that always fails
+**     SQLITE_MEMDEBUG               // Debugging version of system malloc()
+**
+** On Windows, if the SQLITE_WIN32_MALLOC_VALIDATE macro is defined and the
+** assert() macro is enabled, each call into the Win32 native heap subsystem
+** will cause HeapValidate to be called.  If heap validation should fail, an
+** assertion will be triggered.
+**
+** If none of the above are defined, then set SQLITE_SYSTEM_MALLOC as
+** the default.
+*/
+#if defined(SQLITE_SYSTEM_MALLOC) \
+  + defined(SQLITE_WIN32_MALLOC) \
+  + defined(SQLITE_ZERO_MALLOC) \
+  + defined(SQLITE_MEMDEBUG)>1
+# error "Two or more of the following compile-time configuration options\
+ are defined but at most one is allowed:\
+ SQLITE_SYSTEM_MALLOC, SQLITE_WIN32_MALLOC, SQLITE_MEMDEBUG,\
+ SQLITE_ZERO_MALLOC"
+#endif
+#if defined(SQLITE_SYSTEM_MALLOC) \
+  + defined(SQLITE_WIN32_MALLOC) \
+  + defined(SQLITE_ZERO_MALLOC) \
+  + defined(SQLITE_MEMDEBUG)==0
+# define SQLITE_SYSTEM_MALLOC 1
+#endif
+
+/*
+** If SQLITE_MALLOC_SOFT_LIMIT is not zero, then try to keep the
+** sizes of memory allocations below this value where possible.
+*/
+#if !defined(SQLITE_MALLOC_SOFT_LIMIT)
+# define SQLITE_MALLOC_SOFT_LIMIT 1024
+#endif
+
+/*
+** We need to define _XOPEN_SOURCE as follows in order to enable
+** recursive mutexes on most Unix systems and fchmod() on OpenBSD.
+** But _XOPEN_SOURCE define causes problems for Mac OS X, so omit
+** it.
+*/
+#if !defined(_XOPEN_SOURCE) && !defined(__DARWIN__) && !defined(__APPLE__)
+#  define _XOPEN_SOURCE 600
+#endif
+
+/*
+** NDEBUG and SQLITE_DEBUG are opposites.  It should always be true that
+** defined(NDEBUG)==!defined(SQLITE_DEBUG).  If this is not currently true,
+** make it true by defining or undefining NDEBUG.
+**
+** Setting NDEBUG makes the code smaller and faster by disabling the
+** assert() statements in the code.  So we want the default action
+** to be for NDEBUG to be set and NDEBUG to be undefined only if SQLITE_DEBUG
+** is set.  Thus NDEBUG becomes an opt-in rather than an opt-out
+** feature.
+*/
+#if !defined(NDEBUG) && !defined(SQLITE_DEBUG)
+# define NDEBUG 1
+#endif
+#if defined(NDEBUG) && defined(SQLITE_DEBUG)
+# undef NDEBUG
+#endif
+
+/*
+** Enable SQLITE_ENABLE_EXPLAIN_COMMENTS if SQLITE_DEBUG is turned on.
+*/
+#if !defined(SQLITE_ENABLE_EXPLAIN_COMMENTS) && defined(SQLITE_DEBUG)
+# define SQLITE_ENABLE_EXPLAIN_COMMENTS 1
+#endif
+
+/*
+** The testcase() macro is used to aid in coverage testing.  When
+** doing coverage testing, the condition inside the argument to
+** testcase() must be evaluated both true and false in order to
+** get full branch coverage.  The testcase() macro is inserted
+** to help ensure adequate test coverage in places where simple
+** condition/decision coverage is inadequate.  For example, testcase()
+** can be used to make sure boundary values are tested.  For
+** bitmask tests, testcase() can be used to make sure each bit
+** is significant and used at least once.  On switch statements
+** where multiple cases go to the same block of code, testcase()
+** can insure that all cases are evaluated.
+**
+*/
+#ifdef SQLITE_COVERAGE_TEST
+SQLITE_PRIVATE   void sqlite3Coverage(int);
+# define testcase(X)  if( X ){ sqlite3Coverage(__LINE__); }
+#else
+# define testcase(X)
+#endif
+
+/*
+** The TESTONLY macro is used to enclose variable declarations or
+** other bits of code that are needed to support the arguments
+** within testcase() and assert() macros.
+*/
+#if !defined(NDEBUG) || defined(SQLITE_COVERAGE_TEST)
+# define TESTONLY(X)  X
+#else
+# define TESTONLY(X)
+#endif
+
+/*
+** Sometimes we need a small amount of code such as a variable initialization
+** to setup for a later assert() statement.  We do not want this code to
+** appear when assert() is disabled.  The following macro is therefore
+** used to contain that setup code.  The "VVA" acronym stands for
+** "Verification, Validation, and Accreditation".  In other words, the
+** code within VVA_ONLY() will only run during verification processes.
+*/
+#ifndef NDEBUG
+# define VVA_ONLY(X)  X
+#else
+# define VVA_ONLY(X)
+#endif
+
+/*
+** The ALWAYS and NEVER macros surround boolean expressions which
+** are intended to always be true or false, respectively.  Such
+** expressions could be omitted from the code completely.  But they
+** are included in a few cases in order to enhance the resilience
+** of SQLite to unexpected behavior - to make the code "self-healing"
+** or "ductile" rather than being "brittle" and crashing at the first
+** hint of unplanned behavior.
+**
+** In other words, ALWAYS and NEVER are added for defensive code.
+**
+** When doing coverage testing ALWAYS and NEVER are hard-coded to
+** be true and false so that the unreachable code they specify will
+** not be counted as untested code.
+*/
+#if defined(SQLITE_COVERAGE_TEST) || defined(SQLITE_MUTATION_TEST)
+# define ALWAYS(X)      (1)
+# define NEVER(X)       (0)
+#elif !defined(NDEBUG)
+# define ALWAYS(X)      ((X)?1:(assert(0),0))
+# define NEVER(X)       ((X)?(assert(0),1):0)
+#else
+# define ALWAYS(X)      (X)
+# define NEVER(X)       (X)
+#endif
+
+/*
+** Some malloc failures are only possible if SQLITE_TEST_REALLOC_STRESS is
+** defined.  We need to defend against those failures when testing with
+** SQLITE_TEST_REALLOC_STRESS, but we don't want the unreachable branches
+** during a normal build.  The following macro can be used to disable tests
+** that are always false except when SQLITE_TEST_REALLOC_STRESS is set.
+*/
+#if defined(SQLITE_TEST_REALLOC_STRESS)
+# define ONLY_IF_REALLOC_STRESS(X)  (X)
+#elif !defined(NDEBUG)
+# define ONLY_IF_REALLOC_STRESS(X)  ((X)?(assert(0),1):0)
+#else
+# define ONLY_IF_REALLOC_STRESS(X)  (0)
+#endif
+
+/*
+** Declarations used for tracing the operating system interfaces.
+*/
+#if defined(SQLITE_FORCE_OS_TRACE) || defined(SQLITE_TEST) || \
+    (defined(SQLITE_DEBUG) && SQLITE_OS_WIN)
+  extern int sqlite3OSTrace;
+# define OSTRACE(X)          if( sqlite3OSTrace ) sqlite3DebugPrintf X
+# define SQLITE_HAVE_OS_TRACE
+#else
+# define OSTRACE(X)
+# undef  SQLITE_HAVE_OS_TRACE
+#endif
+
+/*
+** Is the sqlite3ErrName() function needed in the build?  Currently,
+** it is needed by "mutex_w32.c" (when debugging), "os_win.c" (when
+** OSTRACE is enabled), and by several "test*.c" files (which are
+** compiled using SQLITE_TEST).
+*/
+#if defined(SQLITE_HAVE_OS_TRACE) || defined(SQLITE_TEST) || \
+    (defined(SQLITE_DEBUG) && SQLITE_OS_WIN)
+# define SQLITE_NEED_ERR_NAME
+#else
+# undef  SQLITE_NEED_ERR_NAME
+#endif
+
+/*
+** SQLITE_ENABLE_EXPLAIN_COMMENTS is incompatible with SQLITE_OMIT_EXPLAIN
+*/
+#ifdef SQLITE_OMIT_EXPLAIN
+# undef SQLITE_ENABLE_EXPLAIN_COMMENTS
+#endif
+
+/*
+** Return true (non-zero) if the input is an integer that is too large
+** to fit in 32-bits.  This macro is used inside of various testcase()
+** macros to verify that we have tested SQLite for large-file support.
+*/
+#define IS_BIG_INT(X)  (((X)&~(i64)0xffffffff)!=0)
+
+/*
+** The macro unlikely() is a hint that surrounds a boolean
+** expression that is usually false.  Macro likely() surrounds
+** a boolean expression that is usually true.  These hints could,
+** in theory, be used by the compiler to generate better code, but
+** currently they are just comments for human readers.
+*/
+#define likely(X)    (X)
+#define unlikely(X)  (X)
+
+/************** Include hash.h in the middle of sqliteInt.h ******************/
+/************** Begin file hash.h ********************************************/
+/*
+** 2001 September 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This is the header file for the generic hash-table implementation
+** used in SQLite.
+*/
+#ifndef SQLITE_HASH_H
+#define SQLITE_HASH_H
+
+/* Forward declarations of structures. */
+typedef struct Hash Hash;
+typedef struct HashElem HashElem;
+
+/* A complete hash table is an instance of the following structure.
+** The internals of this structure are intended to be opaque -- client
+** code should not attempt to access or modify the fields of this structure
+** directly.  Change this structure only by using the routines below.
+** However, some of the "procedures" and "functions" for modifying and
+** accessing this structure are really macros, so we can't really make
+** this structure opaque.
+**
+** All elements of the hash table are on a single doubly-linked list.
+** Hash.first points to the head of this list.
+**
+** There are Hash.htsize buckets.  Each bucket points to a spot in
+** the global doubly-linked list.  The contents of the bucket are the
+** element pointed to plus the next _ht.count-1 elements in the list.
+**
+** Hash.htsize and Hash.ht may be zero.  In that case lookup is done
+** by a linear search of the global list.  For small tables, the 
+** Hash.ht table is never allocated because if there are few elements
+** in the table, it is faster to do a linear search than to manage
+** the hash table.
+*/
+struct Hash {
+  unsigned int htsize;      /* Number of buckets in the hash table */
+  unsigned int count;       /* Number of entries in this table */
+  HashElem *first;          /* The first element of the array */
+  struct _ht {              /* the hash table */
+    int count;                 /* Number of entries with this hash */
+    HashElem *chain;           /* Pointer to first entry with this hash */
+  } *ht;
+};
+
+/* Each element in the hash table is an instance of the following 
+** structure.  All elements are stored on a single doubly-linked list.
+**
+** Again, this structure is intended to be opaque, but it can't really
+** be opaque because it is used by macros.
+*/
+struct HashElem {
+  HashElem *next, *prev;       /* Next and previous elements in the table */
+  void *data;                  /* Data associated with this element */
+  const char *pKey;            /* Key associated with this element */
+};
+
+/*
+** Access routines.  To delete, insert a NULL pointer.
+*/
+SQLITE_PRIVATE void sqlite3HashInit(Hash*);
+SQLITE_PRIVATE void *sqlite3HashInsert(Hash*, const char *pKey, void *pData);
+SQLITE_PRIVATE void *sqlite3HashFind(const Hash*, const char *pKey);
+SQLITE_PRIVATE void sqlite3HashClear(Hash*);
+
+/*
+** Macros for looping over all elements of a hash table.  The idiom is
+** like this:
+**
+**   Hash h;
+**   HashElem *p;
+**   ...
+**   for(p=sqliteHashFirst(&h); p; p=sqliteHashNext(p)){
+**     SomeStructure *pData = sqliteHashData(p);
+**     // do something with pData
+**   }
+*/
+#define sqliteHashFirst(H)  ((H)->first)
+#define sqliteHashNext(E)   ((E)->next)
+#define sqliteHashData(E)   ((E)->data)
+/* #define sqliteHashKey(E)    ((E)->pKey) // NOT USED */
+/* #define sqliteHashKeysize(E) ((E)->nKey)  // NOT USED */
+
+/*
+** Number of entries in a hash table
+*/
+/* #define sqliteHashCount(H)  ((H)->count) // NOT USED */
+
+#endif /* SQLITE_HASH_H */
+
+/************** End of hash.h ************************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+/************** Include parse.h in the middle of sqliteInt.h *****************/
+/************** Begin file parse.h *******************************************/
+#define TK_SEMI                             1
+#define TK_EXPLAIN                          2
+#define TK_QUERY                            3
+#define TK_PLAN                             4
+#define TK_BEGIN                            5
+#define TK_TRANSACTION                      6
+#define TK_DEFERRED                         7
+#define TK_IMMEDIATE                        8
+#define TK_EXCLUSIVE                        9
+#define TK_COMMIT                          10
+#define TK_END                             11
+#define TK_ROLLBACK                        12
+#define TK_SAVEPOINT                       13
+#define TK_RELEASE                         14
+#define TK_TO                              15
+#define TK_TABLE                           16
+#define TK_CREATE                          17
+#define TK_IF                              18
+#define TK_NOT                             19
+#define TK_EXISTS                          20
+#define TK_TEMP                            21
+#define TK_LP                              22
+#define TK_RP                              23
+#define TK_AS                              24
+#define TK_WITHOUT                         25
+#define TK_COMMA                           26
+#define TK_OR                              27
+#define TK_AND                             28
+#define TK_IS                              29
+#define TK_MATCH                           30
+#define TK_LIKE_KW                         31
+#define TK_BETWEEN                         32
+#define TK_IN                              33
+#define TK_ISNULL                          34
+#define TK_NOTNULL                         35
+#define TK_NE                              36
+#define TK_EQ                              37
+#define TK_GT                              38
+#define TK_LE                              39
+#define TK_LT                              40
+#define TK_GE                              41
+#define TK_ESCAPE                          42
+#define TK_BITAND                          43
+#define TK_BITOR                           44
+#define TK_LSHIFT                          45
+#define TK_RSHIFT                          46
+#define TK_PLUS                            47
+#define TK_MINUS                           48
+#define TK_STAR                            49
+#define TK_SLASH                           50
+#define TK_REM                             51
+#define TK_CONCAT                          52
+#define TK_COLLATE                         53
+#define TK_BITNOT                          54
+#define TK_ID                              55
+#define TK_INDEXED                         56
+#define TK_ABORT                           57
+#define TK_ACTION                          58
+#define TK_AFTER                           59
+#define TK_ANALYZE                         60
+#define TK_ASC                             61
+#define TK_ATTACH                          62
+#define TK_BEFORE                          63
+#define TK_BY                              64
+#define TK_CASCADE                         65
+#define TK_CAST                            66
+#define TK_COLUMNKW                        67
+#define TK_CONFLICT                        68
+#define TK_DATABASE                        69
+#define TK_DESC                            70
+#define TK_DETACH                          71
+#define TK_EACH                            72
+#define TK_FAIL                            73
+#define TK_FOR                             74
+#define TK_IGNORE                          75
+#define TK_INITIALLY                       76
+#define TK_INSTEAD                         77
+#define TK_NO                              78
+#define TK_KEY                             79
+#define TK_OF                              80
+#define TK_OFFSET                          81
+#define TK_PRAGMA                          82
+#define TK_RAISE                           83
+#define TK_RECURSIVE                       84
+#define TK_REPLACE                         85
+#define TK_RESTRICT                        86
+#define TK_ROW                             87
+#define TK_TRIGGER                         88
+#define TK_VACUUM                          89
+#define TK_VIEW                            90
+#define TK_VIRTUAL                         91
+#define TK_WITH                            92
+#define TK_REINDEX                         93
+#define TK_RENAME                          94
+#define TK_CTIME_KW                        95
+#define TK_ANY                             96
+#define TK_STRING                          97
+#define TK_JOIN_KW                         98
+#define TK_CONSTRAINT                      99
+#define TK_DEFAULT                        100
+#define TK_NULL                           101
+#define TK_PRIMARY                        102
+#define TK_UNIQUE                         103
+#define TK_CHECK                          104
+#define TK_REFERENCES                     105
+#define TK_AUTOINCR                       106
+#define TK_ON                             107
+#define TK_INSERT                         108
+#define TK_DELETE                         109
+#define TK_UPDATE                         110
+#define TK_SET                            111
+#define TK_DEFERRABLE                     112
+#define TK_FOREIGN                        113
+#define TK_DROP                           114
+#define TK_UNION                          115
+#define TK_ALL                            116
+#define TK_EXCEPT                         117
+#define TK_INTERSECT                      118
+#define TK_SELECT                         119
+#define TK_VALUES                         120
+#define TK_DISTINCT                       121
+#define TK_DOT                            122
+#define TK_FROM                           123
+#define TK_JOIN                           124
+#define TK_USING                          125
+#define TK_ORDER                          126
+#define TK_GROUP                          127
+#define TK_HAVING                         128
+#define TK_LIMIT                          129
+#define TK_WHERE                          130
+#define TK_INTO                           131
+#define TK_FLOAT                          132
+#define TK_BLOB                           133
+#define TK_INTEGER                        134
+#define TK_VARIABLE                       135
+#define TK_CASE                           136
+#define TK_WHEN                           137
+#define TK_THEN                           138
+#define TK_ELSE                           139
+#define TK_INDEX                          140
+#define TK_ALTER                          141
+#define TK_ADD                            142
+#define TK_TO_TEXT                        143
+#define TK_TO_BLOB                        144
+#define TK_TO_NUMERIC                     145
+#define TK_TO_INT                         146
+#define TK_TO_REAL                        147
+#define TK_ISNOT                          148
+#define TK_END_OF_FILE                    149
+#define TK_UNCLOSED_STRING                150
+#define TK_FUNCTION                       151
+#define TK_COLUMN                         152
+#define TK_AGG_FUNCTION                   153
+#define TK_AGG_COLUMN                     154
+#define TK_UMINUS                         155
+#define TK_UPLUS                          156
+#define TK_REGISTER                       157
+#define TK_VECTOR                         158
+#define TK_SELECT_COLUMN                  159
+#define TK_ASTERISK                       160
+#define TK_SPAN                           161
+#define TK_SPACE                          162
+#define TK_ILLEGAL                        163
+
+/* The token codes above must all fit in 8 bits */
+#define TKFLG_MASK           0xff  
+
+/* Flags that can be added to a token code when it is not
+** being stored in a u8: */
+#define TKFLG_DONTFOLD       0x100  /* Omit constant folding optimizations */
+
+/************** End of parse.h ***********************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <stddef.h>
+
+/*
+** If compiling for a processor that lacks floating point support,
+** substitute integer for floating-point
+*/
+#ifdef SQLITE_OMIT_FLOATING_POINT
+# define double sqlite_int64
+# define float sqlite_int64
+# define LONGDOUBLE_TYPE sqlite_int64
+# ifndef SQLITE_BIG_DBL
+#   define SQLITE_BIG_DBL (((sqlite3_int64)1)<<50)
+# endif
+# define SQLITE_OMIT_DATETIME_FUNCS 1
+# define SQLITE_OMIT_TRACE 1
+# undef SQLITE_MIXED_ENDIAN_64BIT_FLOAT
+# undef SQLITE_HAVE_ISNAN
+#endif
+#ifndef SQLITE_BIG_DBL
+# define SQLITE_BIG_DBL (1e99)
+#endif
+
+/*
+** OMIT_TEMPDB is set to 1 if SQLITE_OMIT_TEMPDB is defined, or 0
+** afterward. Having this macro allows us to cause the C compiler
+** to omit code used by TEMP tables without messy #ifndef statements.
+*/
+#ifdef SQLITE_OMIT_TEMPDB
+#define OMIT_TEMPDB 1
+#else
+#define OMIT_TEMPDB 0
+#endif
+
+/*
+** The "file format" number is an integer that is incremented whenever
+** the VDBE-level file format changes.  The following macros define the
+** the default file format for new databases and the maximum file format
+** that the library can read.
+*/
+#define SQLITE_MAX_FILE_FORMAT 4
+#ifndef SQLITE_DEFAULT_FILE_FORMAT
+# define SQLITE_DEFAULT_FILE_FORMAT 4
+#endif
+
+/*
+** Determine whether triggers are recursive by default.  This can be
+** changed at run-time using a pragma.
+*/
+#ifndef SQLITE_DEFAULT_RECURSIVE_TRIGGERS
+# define SQLITE_DEFAULT_RECURSIVE_TRIGGERS 0
+#endif
+
+/*
+** Provide a default value for SQLITE_TEMP_STORE in case it is not specified
+** on the command-line
+*/
+#ifndef SQLITE_TEMP_STORE
+# define SQLITE_TEMP_STORE 1
+# define SQLITE_TEMP_STORE_xc 1  /* Exclude from ctime.c */
+#endif
+
+/*
+** If no value has been provided for SQLITE_MAX_WORKER_THREADS, or if
+** SQLITE_TEMP_STORE is set to 3 (never use temporary files), set it
+** to zero.
+*/
+#if SQLITE_TEMP_STORE==3 || SQLITE_THREADSAFE==0
+# undef SQLITE_MAX_WORKER_THREADS
+# define SQLITE_MAX_WORKER_THREADS 0
+#endif
+#ifndef SQLITE_MAX_WORKER_THREADS
+# define SQLITE_MAX_WORKER_THREADS 8
+#endif
+#ifndef SQLITE_DEFAULT_WORKER_THREADS
+# define SQLITE_DEFAULT_WORKER_THREADS 0
+#endif
+#if SQLITE_DEFAULT_WORKER_THREADS>SQLITE_MAX_WORKER_THREADS
+# undef SQLITE_MAX_WORKER_THREADS
+# define SQLITE_MAX_WORKER_THREADS SQLITE_DEFAULT_WORKER_THREADS
+#endif
+
+/*
+** The default initial allocation for the pagecache when using separate
+** pagecaches for each database connection.  A positive number is the
+** number of pages.  A negative number N translations means that a buffer
+** of -1024*N bytes is allocated and used for as many pages as it will hold.
+*/
+#ifndef SQLITE_DEFAULT_PCACHE_INITSZ
+# define SQLITE_DEFAULT_PCACHE_INITSZ 100
+#endif
+
+/*
+** GCC does not define the offsetof() macro so we'll have to do it
+** ourselves.
+*/
+#ifndef offsetof
+#define offsetof(STRUCTURE,FIELD) ((int)((char*)&((STRUCTURE*)0)->FIELD))
+#endif
+
+/*
+** Macros to compute minimum and maximum of two numbers.
+*/
+#ifndef MIN
+# define MIN(A,B) ((A)<(B)?(A):(B))
+#endif
+#ifndef MAX
+# define MAX(A,B) ((A)>(B)?(A):(B))
+#endif
+
+/*
+** Swap two objects of type TYPE.
+*/
+#define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}
+
+/*
+** Check to see if this machine uses EBCDIC.  (Yes, believe it or
+** not, there are still machines out there that use EBCDIC.)
+*/
+#if 'A' == '\301'
+# define SQLITE_EBCDIC 1
+#else
+# define SQLITE_ASCII 1
+#endif
+
+/*
+** Integers of known sizes.  These typedefs might change for architectures
+** where the sizes very.  Preprocessor macros are available so that the
+** types can be conveniently redefined at compile-type.  Like this:
+**
+**         cc '-DUINTPTR_TYPE=long long int' ...
+*/
+#ifndef UINT32_TYPE
+# ifdef HAVE_UINT32_T
+#  define UINT32_TYPE uint32_t
+# else
+#  define UINT32_TYPE unsigned int
+# endif
+#endif
+#ifndef UINT16_TYPE
+# ifdef HAVE_UINT16_T
+#  define UINT16_TYPE uint16_t
+# else
+#  define UINT16_TYPE unsigned short int
+# endif
+#endif
+#ifndef INT16_TYPE
+# ifdef HAVE_INT16_T
+#  define INT16_TYPE int16_t
+# else
+#  define INT16_TYPE short int
+# endif
+#endif
+#ifndef UINT8_TYPE
+# ifdef HAVE_UINT8_T
+#  define UINT8_TYPE uint8_t
+# else
+#  define UINT8_TYPE unsigned char
+# endif
+#endif
+#ifndef INT8_TYPE
+# ifdef HAVE_INT8_T
+#  define INT8_TYPE int8_t
+# else
+#  define INT8_TYPE signed char
+# endif
+#endif
+#ifndef LONGDOUBLE_TYPE
+# define LONGDOUBLE_TYPE long double
+#endif
+typedef sqlite_int64 i64;          /* 8-byte signed integer */
+typedef sqlite_uint64 u64;         /* 8-byte unsigned integer */
+typedef UINT32_TYPE u32;           /* 4-byte unsigned integer */
+typedef UINT16_TYPE u16;           /* 2-byte unsigned integer */
+typedef INT16_TYPE i16;            /* 2-byte signed integer */
+typedef UINT8_TYPE u8;             /* 1-byte unsigned integer */
+typedef INT8_TYPE i8;              /* 1-byte signed integer */
+
+/*
+** SQLITE_MAX_U32 is a u64 constant that is the maximum u64 value
+** that can be stored in a u32 without loss of data.  The value
+** is 0x00000000ffffffff.  But because of quirks of some compilers, we
+** have to specify the value in the less intuitive manner shown:
+*/
+#define SQLITE_MAX_U32  ((((u64)1)<<32)-1)
+
+/*
+** The datatype used to store estimates of the number of rows in a
+** table or index.  This is an unsigned integer type.  For 99.9% of
+** the world, a 32-bit integer is sufficient.  But a 64-bit integer
+** can be used at compile-time if desired.
+*/
+#ifdef SQLITE_64BIT_STATS
+ typedef u64 tRowcnt;    /* 64-bit only if requested at compile-time */
+#else
+ typedef u32 tRowcnt;    /* 32-bit is the default */
+#endif
+
+/*
+** Estimated quantities used for query planning are stored as 16-bit
+** logarithms.  For quantity X, the value stored is 10*log2(X).  This
+** gives a possible range of values of approximately 1.0e986 to 1e-986.
+** But the allowed values are "grainy".  Not every value is representable.
+** For example, quantities 16 and 17 are both represented by a LogEst
+** of 40.  However, since LogEst quantities are suppose to be estimates,
+** not exact values, this imprecision is not a problem.
+**
+** "LogEst" is short for "Logarithmic Estimate".
+**
+** Examples:
+**      1 -> 0              20 -> 43          10000 -> 132
+**      2 -> 10             25 -> 46          25000 -> 146
+**      3 -> 16            100 -> 66        1000000 -> 199
+**      4 -> 20           1000 -> 99        1048576 -> 200
+**     10 -> 33           1024 -> 100    4294967296 -> 320
+**
+** The LogEst can be negative to indicate fractional values.
+** Examples:
+**
+**    0.5 -> -10           0.1 -> -33        0.0625 -> -40
+*/
+typedef INT16_TYPE LogEst;
+
+/*
+** Set the SQLITE_PTRSIZE macro to the number of bytes in a pointer
+*/
+#ifndef SQLITE_PTRSIZE
+# if defined(__SIZEOF_POINTER__)
+#   define SQLITE_PTRSIZE __SIZEOF_POINTER__
+# elif defined(i386)     || defined(__i386__)   || defined(_M_IX86) ||    \
+       defined(_M_ARM)   || defined(__arm__)    || defined(__x86)
+#   define SQLITE_PTRSIZE 4
+# else
+#   define SQLITE_PTRSIZE 8
+# endif
+#endif
+
+/* The uptr type is an unsigned integer large enough to hold a pointer
+*/
+#if defined(HAVE_STDINT_H)
+  typedef uintptr_t uptr;
+#elif SQLITE_PTRSIZE==4
+  typedef u32 uptr;
+#else
+  typedef u64 uptr;
+#endif
+
+/*
+** The SQLITE_WITHIN(P,S,E) macro checks to see if pointer P points to
+** something between S (inclusive) and E (exclusive).
+**
+** In other words, S is a buffer and E is a pointer to the first byte after
+** the end of buffer S.  This macro returns true if P points to something
+** contained within the buffer S.
+*/
+#define SQLITE_WITHIN(P,S,E) (((uptr)(P)>=(uptr)(S))&&((uptr)(P)<(uptr)(E)))
+
+
+/*
+** Macros to determine whether the machine is big or little endian,
+** and whether or not that determination is run-time or compile-time.
+**
+** For best performance, an attempt is made to guess at the byte-order
+** using C-preprocessor macros.  If that is unsuccessful, or if
+** -DSQLITE_RUNTIME_BYTEORDER=1 is set, then byte-order is determined
+** at run-time.
+*/
+#if (defined(i386)     || defined(__i386__)   || defined(_M_IX86) ||    \
+     defined(__x86_64) || defined(__x86_64__) || defined(_M_X64)  ||    \
+     defined(_M_AMD64) || defined(_M_ARM)     || defined(__x86)   ||    \
+     defined(__arm__)) && !defined(SQLITE_RUNTIME_BYTEORDER)
+# define SQLITE_BYTEORDER    1234
+# define SQLITE_BIGENDIAN    0
+# define SQLITE_LITTLEENDIAN 1
+# define SQLITE_UTF16NATIVE  SQLITE_UTF16LE
+#endif
+#if (defined(sparc)    || defined(__ppc__))  \
+    && !defined(SQLITE_RUNTIME_BYTEORDER)
+# define SQLITE_BYTEORDER    4321
+# define SQLITE_BIGENDIAN    1
+# define SQLITE_LITTLEENDIAN 0
+# define SQLITE_UTF16NATIVE  SQLITE_UTF16BE
+#endif
+#if !defined(SQLITE_BYTEORDER)
+# ifdef SQLITE_AMALGAMATION
+  const int sqlite3one = 1;
+# else
+  extern const int sqlite3one;
+# endif
+# define SQLITE_BYTEORDER    0     /* 0 means "unknown at compile-time" */
+# define SQLITE_BIGENDIAN    (*(char *)(&sqlite3one)==0)
+# define SQLITE_LITTLEENDIAN (*(char *)(&sqlite3one)==1)
+# define SQLITE_UTF16NATIVE  (SQLITE_BIGENDIAN?SQLITE_UTF16BE:SQLITE_UTF16LE)
+#endif
+
+/*
+** Constants for the largest and smallest possible 64-bit signed integers.
+** These macros are designed to work correctly on both 32-bit and 64-bit
+** compilers.
+*/
+#define LARGEST_INT64  (0xffffffff|(((i64)0x7fffffff)<<32))
+#define SMALLEST_INT64 (((i64)-1) - LARGEST_INT64)
+
+/*
+** Round up a number to the next larger multiple of 8.  This is used
+** to force 8-byte alignment on 64-bit architectures.
+*/
+#define ROUND8(x)     (((x)+7)&~7)
+
+/*
+** Round down to the nearest multiple of 8
+*/
+#define ROUNDDOWN8(x) ((x)&~7)
+
+/*
+** Assert that the pointer X is aligned to an 8-byte boundary.  This
+** macro is used only within assert() to verify that the code gets
+** all alignment restrictions correct.
+**
+** Except, if SQLITE_4_BYTE_ALIGNED_MALLOC is defined, then the
+** underlying malloc() implementation might return us 4-byte aligned
+** pointers.  In that case, only verify 4-byte alignment.
+*/
+#ifdef SQLITE_4_BYTE_ALIGNED_MALLOC
+# define EIGHT_BYTE_ALIGNMENT(X)   ((((char*)(X) - (char*)0)&3)==0)
+#else
+# define EIGHT_BYTE_ALIGNMENT(X)   ((((char*)(X) - (char*)0)&7)==0)
+#endif
+
+/*
+** Disable MMAP on platforms where it is known to not work
+*/
+#if defined(__OpenBSD__) || defined(__QNXNTO__)
+# undef SQLITE_MAX_MMAP_SIZE
+# define SQLITE_MAX_MMAP_SIZE 0
+#endif
+
+/*
+** Default maximum size of memory used by memory-mapped I/O in the VFS
+*/
+#ifdef __APPLE__
+# include <TargetConditionals.h>
+#endif
+#ifndef SQLITE_MAX_MMAP_SIZE
+# if defined(__linux__) \
+  || defined(_WIN32) \
+  || (defined(__APPLE__) && defined(__MACH__)) \
+  || defined(__sun) \
+  || defined(__FreeBSD__) \
+  || defined(__DragonFly__)
+#   define SQLITE_MAX_MMAP_SIZE 0x7fff0000  /* 2147418112 */
+# else
+#   define SQLITE_MAX_MMAP_SIZE 0
+# endif
+# define SQLITE_MAX_MMAP_SIZE_xc 1 /* exclude from ctime.c */
+#endif
+
+/*
+** The default MMAP_SIZE is zero on all platforms.  Or, even if a larger
+** default MMAP_SIZE is specified at compile-time, make sure that it does
+** not exceed the maximum mmap size.
+*/
+#ifndef SQLITE_DEFAULT_MMAP_SIZE
+# define SQLITE_DEFAULT_MMAP_SIZE 0
+# define SQLITE_DEFAULT_MMAP_SIZE_xc 1  /* Exclude from ctime.c */
+#endif
+#if SQLITE_DEFAULT_MMAP_SIZE>SQLITE_MAX_MMAP_SIZE
+# undef SQLITE_DEFAULT_MMAP_SIZE
+# define SQLITE_DEFAULT_MMAP_SIZE SQLITE_MAX_MMAP_SIZE
+#endif
+
+/*
+** Only one of SQLITE_ENABLE_STAT3 or SQLITE_ENABLE_STAT4 can be defined.
+** Priority is given to SQLITE_ENABLE_STAT4.  If either are defined, also
+** define SQLITE_ENABLE_STAT3_OR_STAT4
+*/
+#ifdef SQLITE_ENABLE_STAT4
+# undef SQLITE_ENABLE_STAT3
+# define SQLITE_ENABLE_STAT3_OR_STAT4 1
+#elif SQLITE_ENABLE_STAT3
+# define SQLITE_ENABLE_STAT3_OR_STAT4 1
+#elif SQLITE_ENABLE_STAT3_OR_STAT4
+# undef SQLITE_ENABLE_STAT3_OR_STAT4
+#endif
+
+/*
+** SELECTTRACE_ENABLED will be either 1 or 0 depending on whether or not
+** the Select query generator tracing logic is turned on.
+*/
+#if defined(SQLITE_DEBUG) || defined(SQLITE_ENABLE_SELECTTRACE)
+# define SELECTTRACE_ENABLED 1
+#else
+# define SELECTTRACE_ENABLED 0
+#endif
+
+/*
+** An instance of the following structure is used to store the busy-handler
+** callback for a given sqlite handle.
+**
+** The sqlite.busyHandler member of the sqlite struct contains the busy
+** callback for the database handle. Each pager opened via the sqlite
+** handle is passed a pointer to sqlite.busyHandler. The busy-handler
+** callback is currently invoked only from within pager.c.
+*/
+typedef struct BusyHandler BusyHandler;
+struct BusyHandler {
+  int (*xFunc)(void *,int);  /* The busy callback */
+  void *pArg;                /* First arg to busy callback */
+  int nBusy;                 /* Incremented with each busy call */
+};
+
+/*
+** Name of the master database table.  The master database table
+** is a special table that holds the names and attributes of all
+** user tables and indices.
+*/
+#define MASTER_NAME       "sqlite_master"
+#define TEMP_MASTER_NAME  "sqlite_temp_master"
+
+/*
+** The root-page of the master database table.
+*/
+#define MASTER_ROOT       1
+
+/*
+** The name of the schema table.
+*/
+#define SCHEMA_TABLE(x)  ((!OMIT_TEMPDB)&&(x==1)?TEMP_MASTER_NAME:MASTER_NAME)
+
+/*
+** A convenience macro that returns the number of elements in
+** an array.
+*/
+#define ArraySize(X)    ((int)(sizeof(X)/sizeof(X[0])))
+
+/*
+** Determine if the argument is a power of two
+*/
+#define IsPowerOfTwo(X) (((X)&((X)-1))==0)
+
+/*
+** The following value as a destructor means to use sqlite3DbFree().
+** The sqlite3DbFree() routine requires two parameters instead of the
+** one parameter that destructors normally want.  So we have to introduce
+** this magic value that the code knows to handle differently.  Any
+** pointer will work here as long as it is distinct from SQLITE_STATIC
+** and SQLITE_TRANSIENT.
+*/
+#define SQLITE_DYNAMIC   ((sqlite3_destructor_type)sqlite3MallocSize)
+
+/*
+** When SQLITE_OMIT_WSD is defined, it means that the target platform does
+** not support Writable Static Data (WSD) such as global and static variables.
+** All variables must either be on the stack or dynamically allocated from
+** the heap.  When WSD is unsupported, the variable declarations scattered
+** throughout the SQLite code must become constants instead.  The SQLITE_WSD
+** macro is used for this purpose.  And instead of referencing the variable
+** directly, we use its constant as a key to lookup the run-time allocated
+** buffer that holds real variable.  The constant is also the initializer
+** for the run-time allocated buffer.
+**
+** In the usual case where WSD is supported, the SQLITE_WSD and GLOBAL
+** macros become no-ops and have zero performance impact.
+*/
+#ifdef SQLITE_OMIT_WSD
+  #define SQLITE_WSD const
+  #define GLOBAL(t,v) (*(t*)sqlite3_wsd_find((void*)&(v), sizeof(v)))
+  #define sqlite3GlobalConfig GLOBAL(struct Sqlite3Config, sqlite3Config)
+SQLITE_API int sqlite3_wsd_init(int N, int J);
+SQLITE_API void *sqlite3_wsd_find(void *K, int L);
+#else
+  #define SQLITE_WSD
+  #define GLOBAL(t,v) v
+  #define sqlite3GlobalConfig sqlite3Config
+#endif
+
+/*
+** The following macros are used to suppress compiler warnings and to
+** make it clear to human readers when a function parameter is deliberately
+** left unused within the body of a function. This usually happens when
+** a function is called via a function pointer. For example the
+** implementation of an SQL aggregate step callback may not use the
+** parameter indicating the number of arguments passed to the aggregate,
+** if it knows that this is enforced elsewhere.
+**
+** When a function parameter is not used at all within the body of a function,
+** it is generally named "NotUsed" or "NotUsed2" to make things even clearer.
+** However, these macros may also be used to suppress warnings related to
+** parameters that may or may not be used depending on compilation options.
+** For example those parameters only used in assert() statements. In these
+** cases the parameters are named as per the usual conventions.
+*/
+#define UNUSED_PARAMETER(x) (void)(x)
+#define UNUSED_PARAMETER2(x,y) UNUSED_PARAMETER(x),UNUSED_PARAMETER(y)
+
+/*
+** Forward references to structures
+*/
+typedef struct AggInfo AggInfo;
+typedef struct AuthContext AuthContext;
+typedef struct AutoincInfo AutoincInfo;
+typedef struct Bitvec Bitvec;
+typedef struct CollSeq CollSeq;
+typedef struct Column Column;
+typedef struct Db Db;
+typedef struct Schema Schema;
+typedef struct Expr Expr;
+typedef struct ExprList ExprList;
+typedef struct ExprSpan ExprSpan;
+typedef struct FKey FKey;
+typedef struct FuncDestructor FuncDestructor;
+typedef struct FuncDef FuncDef;
+typedef struct FuncDefHash FuncDefHash;
+typedef struct IdList IdList;
+typedef struct Index Index;
+typedef struct IndexSample IndexSample;
+typedef struct KeyClass KeyClass;
+typedef struct KeyInfo KeyInfo;
+typedef struct Lookaside Lookaside;
+typedef struct LookasideSlot LookasideSlot;
+typedef struct Module Module;
+typedef struct NameContext NameContext;
+typedef struct Parse Parse;
+typedef struct PreUpdate PreUpdate;
+typedef struct PrintfArguments PrintfArguments;
+typedef struct RowSet RowSet;
+typedef struct Savepoint Savepoint;
+typedef struct Select Select;
+typedef struct SQLiteThread SQLiteThread;
+typedef struct SelectDest SelectDest;
+typedef struct SrcList SrcList;
+typedef struct StrAccum StrAccum;
+typedef struct Table Table;
+typedef struct TableLock TableLock;
+typedef struct Token Token;
+typedef struct TreeView TreeView;
+typedef struct Trigger Trigger;
+typedef struct TriggerPrg TriggerPrg;
+typedef struct TriggerStep TriggerStep;
+typedef struct UnpackedRecord UnpackedRecord;
+typedef struct VTable VTable;
+typedef struct VtabCtx VtabCtx;
+typedef struct Walker Walker;
+typedef struct WhereInfo WhereInfo;
+typedef struct With With;
+
+/*
+** Defer sourcing vdbe.h and btree.h until after the "u8" and
+** "BusyHandler" typedefs. vdbe.h also requires a few of the opaque
+** pointer types (i.e. FuncDef) defined above.
+*/
+/************** Include btree.h in the middle of sqliteInt.h *****************/
+/************** Begin file btree.h *******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This header file defines the interface that the sqlite B-Tree file
+** subsystem.  See comments in the source code for a detailed description
+** of what each interface routine does.
+*/
+#ifndef SQLITE_BTREE_H
+#define SQLITE_BTREE_H
+
+/* TODO: This definition is just included so other modules compile. It
+** needs to be revisited.
+*/
+#define SQLITE_N_BTREE_META 16
+
+/*
+** If defined as non-zero, auto-vacuum is enabled by default. Otherwise
+** it must be turned on for each database using "PRAGMA auto_vacuum = 1".
+*/
+#ifndef SQLITE_DEFAULT_AUTOVACUUM
+  #define SQLITE_DEFAULT_AUTOVACUUM 0
+#endif
+
+#define BTREE_AUTOVACUUM_NONE 0        /* Do not do auto-vacuum */
+#define BTREE_AUTOVACUUM_FULL 1        /* Do full auto-vacuum */
+#define BTREE_AUTOVACUUM_INCR 2        /* Incremental vacuum */
+
+/*
+** Forward declarations of structure
+*/
+typedef struct Btree Btree;
+typedef struct BtCursor BtCursor;
+typedef struct BtShared BtShared;
+typedef struct BtreePayload BtreePayload;
+
+
+SQLITE_PRIVATE int sqlite3BtreeOpen(
+  sqlite3_vfs *pVfs,       /* VFS to use with this b-tree */
+  const char *zFilename,   /* Name of database file to open */
+  sqlite3 *db,             /* Associated database connection */
+  Btree **ppBtree,         /* Return open Btree* here */
+  int flags,               /* Flags */
+  int vfsFlags             /* Flags passed through to VFS open */
+);
+
+/* The flags parameter to sqlite3BtreeOpen can be the bitwise or of the
+** following values.
+**
+** NOTE:  These values must match the corresponding PAGER_ values in
+** pager.h.
+*/
+#define BTREE_OMIT_JOURNAL  1  /* Do not create or use a rollback journal */
+#define BTREE_MEMORY        2  /* This is an in-memory DB */
+#define BTREE_SINGLE        4  /* The file contains at most 1 b-tree */
+#define BTREE_UNORDERED     8  /* Use of a hash implementation is OK */
+
+SQLITE_PRIVATE int sqlite3BtreeClose(Btree*);
+SQLITE_PRIVATE int sqlite3BtreeSetCacheSize(Btree*,int);
+SQLITE_PRIVATE int sqlite3BtreeSetSpillSize(Btree*,int);
+#if SQLITE_MAX_MMAP_SIZE>0
+SQLITE_PRIVATE   int sqlite3BtreeSetMmapLimit(Btree*,sqlite3_int64);
+#endif
+SQLITE_PRIVATE int sqlite3BtreeSetPagerFlags(Btree*,unsigned);
+SQLITE_PRIVATE int sqlite3BtreeSetPageSize(Btree *p, int nPagesize, int nReserve, int eFix);
+SQLITE_PRIVATE int sqlite3BtreeGetPageSize(Btree*);
+SQLITE_PRIVATE int sqlite3BtreeMaxPageCount(Btree*,int);
+SQLITE_PRIVATE u32 sqlite3BtreeLastPage(Btree*);
+SQLITE_PRIVATE int sqlite3BtreeSecureDelete(Btree*,int);
+SQLITE_PRIVATE int sqlite3BtreeGetOptimalReserve(Btree*);
+SQLITE_PRIVATE int sqlite3BtreeGetReserveNoMutex(Btree *p);
+SQLITE_PRIVATE int sqlite3BtreeSetAutoVacuum(Btree *, int);
+SQLITE_PRIVATE int sqlite3BtreeGetAutoVacuum(Btree *);
+SQLITE_PRIVATE int sqlite3BtreeBeginTrans(Btree*,int);
+SQLITE_PRIVATE int sqlite3BtreeCommitPhaseOne(Btree*, const char *zMaster);
+SQLITE_PRIVATE int sqlite3BtreeCommitPhaseTwo(Btree*, int);
+SQLITE_PRIVATE int sqlite3BtreeCommit(Btree*);
+SQLITE_PRIVATE int sqlite3BtreeRollback(Btree*,int,int);
+SQLITE_PRIVATE int sqlite3BtreeBeginStmt(Btree*,int);
+SQLITE_PRIVATE int sqlite3BtreeCreateTable(Btree*, int*, int flags);
+SQLITE_PRIVATE int sqlite3BtreeIsInTrans(Btree*);
+SQLITE_PRIVATE int sqlite3BtreeIsInReadTrans(Btree*);
+SQLITE_PRIVATE int sqlite3BtreeIsInBackup(Btree*);
+SQLITE_PRIVATE void *sqlite3BtreeSchema(Btree *, int, void(*)(void *));
+SQLITE_PRIVATE int sqlite3BtreeSchemaLocked(Btree *pBtree);
+#ifndef SQLITE_OMIT_SHARED_CACHE
+SQLITE_PRIVATE int sqlite3BtreeLockTable(Btree *pBtree, int iTab, u8 isWriteLock);
+#endif
+SQLITE_PRIVATE int sqlite3BtreeSavepoint(Btree *, int, int);
+
+SQLITE_PRIVATE const char *sqlite3BtreeGetFilename(Btree *);
+SQLITE_PRIVATE const char *sqlite3BtreeGetJournalname(Btree *);
+SQLITE_PRIVATE int sqlite3BtreeCopyFile(Btree *, Btree *);
+
+SQLITE_PRIVATE int sqlite3BtreeIncrVacuum(Btree *);
+
+/* The flags parameter to sqlite3BtreeCreateTable can be the bitwise OR
+** of the flags shown below.
+**
+** Every SQLite table must have either BTREE_INTKEY or BTREE_BLOBKEY set.
+** With BTREE_INTKEY, the table key is a 64-bit integer and arbitrary data
+** is stored in the leaves.  (BTREE_INTKEY is used for SQL tables.)  With
+** BTREE_BLOBKEY, the key is an arbitrary BLOB and no content is stored
+** anywhere - the key is the content.  (BTREE_BLOBKEY is used for SQL
+** indices.)
+*/
+#define BTREE_INTKEY     1    /* Table has only 64-bit signed integer keys */
+#define BTREE_BLOBKEY    2    /* Table has keys only - no data */
+
+SQLITE_PRIVATE int sqlite3BtreeDropTable(Btree*, int, int*);
+SQLITE_PRIVATE int sqlite3BtreeClearTable(Btree*, int, int*);
+SQLITE_PRIVATE int sqlite3BtreeClearTableOfCursor(BtCursor*);
+SQLITE_PRIVATE int sqlite3BtreeTripAllCursors(Btree*, int, int);
+
+SQLITE_PRIVATE void sqlite3BtreeGetMeta(Btree *pBtree, int idx, u32 *pValue);
+SQLITE_PRIVATE int sqlite3BtreeUpdateMeta(Btree*, int idx, u32 value);
+
+SQLITE_PRIVATE int sqlite3BtreeNewDb(Btree *p);
+
+/*
+** The second parameter to sqlite3BtreeGetMeta or sqlite3BtreeUpdateMeta
+** should be one of the following values. The integer values are assigned 
+** to constants so that the offset of the corresponding field in an
+** SQLite database header may be found using the following formula:
+**
+**   offset = 36 + (idx * 4)
+**
+** For example, the free-page-count field is located at byte offset 36 of
+** the database file header. The incr-vacuum-flag field is located at
+** byte offset 64 (== 36+4*7).
+**
+** The BTREE_DATA_VERSION value is not really a value stored in the header.
+** It is a read-only number computed by the pager.  But we merge it with
+** the header value access routines since its access pattern is the same.
+** Call it a "virtual meta value".
+*/
+#define BTREE_FREE_PAGE_COUNT     0
+#define BTREE_SCHEMA_VERSION      1
+#define BTREE_FILE_FORMAT         2
+#define BTREE_DEFAULT_CACHE_SIZE  3
+#define BTREE_LARGEST_ROOT_PAGE   4
+#define BTREE_TEXT_ENCODING       5
+#define BTREE_USER_VERSION        6
+#define BTREE_INCR_VACUUM         7
+#define BTREE_APPLICATION_ID      8
+#define BTREE_DATA_VERSION        15  /* A virtual meta-value */
+
+/*
+** Kinds of hints that can be passed into the sqlite3BtreeCursorHint()
+** interface.
+**
+** BTREE_HINT_RANGE  (arguments: Expr*, Mem*)
+**
+**     The first argument is an Expr* (which is guaranteed to be constant for
+**     the lifetime of the cursor) that defines constraints on which rows
+**     might be fetched with this cursor.  The Expr* tree may contain
+**     TK_REGISTER nodes that refer to values stored in the array of registers
+**     passed as the second parameter.  In other words, if Expr.op==TK_REGISTER
+**     then the value of the node is the value in Mem[pExpr.iTable].  Any
+**     TK_COLUMN node in the expression tree refers to the Expr.iColumn-th
+**     column of the b-tree of the cursor.  The Expr tree will not contain
+**     any function calls nor subqueries nor references to b-trees other than
+**     the cursor being hinted.
+**
+**     The design of the _RANGE hint is aid b-tree implementations that try
+**     to prefetch content from remote machines - to provide those
+**     implementations with limits on what needs to be prefetched and thereby
+**     reduce network bandwidth.
+**
+** Note that BTREE_HINT_FLAGS with BTREE_BULKLOAD is the only hint used by
+** standard SQLite.  The other hints are provided for extentions that use
+** the SQLite parser and code generator but substitute their own storage
+** engine.
+*/
+#define BTREE_HINT_RANGE 0       /* Range constraints on queries */
+
+/*
+** Values that may be OR'd together to form the argument to the
+** BTREE_HINT_FLAGS hint for sqlite3BtreeCursorHint():
+**
+** The BTREE_BULKLOAD flag is set on index cursors when the index is going
+** to be filled with content that is already in sorted order.
+**
+** The BTREE_SEEK_EQ flag is set on cursors that will get OP_SeekGE or
+** OP_SeekLE opcodes for a range search, but where the range of entries
+** selected will all have the same key.  In other words, the cursor will
+** be used only for equality key searches.
+**
+*/
+#define BTREE_BULKLOAD 0x00000001  /* Used to full index in sorted order */
+#define BTREE_SEEK_EQ  0x00000002  /* EQ seeks only - no range seeks */
+
+/* 
+** Flags passed as the third argument to sqlite3BtreeCursor().
+**
+** For read-only cursors the wrFlag argument is always zero. For read-write
+** cursors it may be set to either (BTREE_WRCSR|BTREE_FORDELETE) or just
+** (BTREE_WRCSR). If the BTREE_FORDELETE bit is set, then the cursor will
+** only be used by SQLite for the following:
+**
+**   * to seek to and then delete specific entries, and/or
+**
+**   * to read values that will be used to create keys that other
+**     BTREE_FORDELETE cursors will seek to and delete.
+**
+** The BTREE_FORDELETE flag is an optimization hint.  It is not used by
+** by this, the native b-tree engine of SQLite, but it is available to
+** alternative storage engines that might be substituted in place of this
+** b-tree system.  For alternative storage engines in which a delete of
+** the main table row automatically deletes corresponding index rows,
+** the FORDELETE flag hint allows those alternative storage engines to
+** skip a lot of work.  Namely:  FORDELETE cursors may treat all SEEK
+** and DELETE operations as no-ops, and any READ operation against a
+** FORDELETE cursor may return a null row: 0x01 0x00.
+*/
+#define BTREE_WRCSR     0x00000004     /* read-write cursor */
+#define BTREE_FORDELETE 0x00000008     /* Cursor is for seek/delete only */
+
+SQLITE_PRIVATE int sqlite3BtreeCursor(
+  Btree*,                              /* BTree containing table to open */
+  int iTable,                          /* Index of root page */
+  int wrFlag,                          /* 1 for writing.  0 for read-only */
+  struct KeyInfo*,                     /* First argument to compare function */
+  BtCursor *pCursor                    /* Space to write cursor structure */
+);
+SQLITE_PRIVATE int sqlite3BtreeCursorSize(void);
+SQLITE_PRIVATE void sqlite3BtreeCursorZero(BtCursor*);
+SQLITE_PRIVATE void sqlite3BtreeCursorHintFlags(BtCursor*, unsigned);
+#ifdef SQLITE_ENABLE_CURSOR_HINTS
+SQLITE_PRIVATE void sqlite3BtreeCursorHint(BtCursor*, int, ...);
+#endif
+
+SQLITE_PRIVATE int sqlite3BtreeCloseCursor(BtCursor*);
+SQLITE_PRIVATE int sqlite3BtreeMovetoUnpacked(
+  BtCursor*,
+  UnpackedRecord *pUnKey,
+  i64 intKey,
+  int bias,
+  int *pRes
+);
+SQLITE_PRIVATE int sqlite3BtreeCursorHasMoved(BtCursor*);
+SQLITE_PRIVATE int sqlite3BtreeCursorRestore(BtCursor*, int*);
+SQLITE_PRIVATE int sqlite3BtreeDelete(BtCursor*, u8 flags);
+
+/* Allowed flags for the 2nd argument to sqlite3BtreeDelete() */
+#define BTREE_SAVEPOSITION 0x02  /* Leave cursor pointing at NEXT or PREV */
+#define BTREE_AUXDELETE    0x04  /* not the primary delete operation */
+
+/* An instance of the BtreePayload object describes the content of a single
+** entry in either an index or table btree.
+**
+** Index btrees (used for indexes and also WITHOUT ROWID tables) contain
+** an arbitrary key and no data.  These btrees have pKey,nKey set to their
+** key and pData,nData,nZero set to zero.
+**
+** Table btrees (used for rowid tables) contain an integer rowid used as
+** the key and passed in the nKey field.  The pKey field is zero.  
+** pData,nData hold the content of the new entry.  nZero extra zero bytes
+** are appended to the end of the content when constructing the entry.
+**
+** This object is used to pass information into sqlite3BtreeInsert().  The
+** same information used to be passed as five separate parameters.  But placing
+** the information into this object helps to keep the interface more 
+** organized and understandable, and it also helps the resulting code to
+** run a little faster by using fewer registers for parameter passing.
+*/
+struct BtreePayload {
+  const void *pKey;       /* Key content for indexes.  NULL for tables */
+  sqlite3_int64 nKey;     /* Size of pKey for indexes.  PRIMARY KEY for tabs */
+  const void *pData;      /* Data for tables.  NULL for indexes */
+  int nData;              /* Size of pData.  0 if none. */
+  int nZero;              /* Extra zero data appended after pData,nData */
+};
+
+SQLITE_PRIVATE int sqlite3BtreeInsert(BtCursor*, const BtreePayload *pPayload,
+                       int bias, int seekResult);
+SQLITE_PRIVATE int sqlite3BtreeFirst(BtCursor*, int *pRes);
+SQLITE_PRIVATE int sqlite3BtreeLast(BtCursor*, int *pRes);
+SQLITE_PRIVATE int sqlite3BtreeNext(BtCursor*, int *pRes);
+SQLITE_PRIVATE int sqlite3BtreeEof(BtCursor*);
+SQLITE_PRIVATE int sqlite3BtreePrevious(BtCursor*, int *pRes);
+SQLITE_PRIVATE i64 sqlite3BtreeIntegerKey(BtCursor*);
+SQLITE_PRIVATE int sqlite3BtreeKey(BtCursor*, u32 offset, u32 amt, void*);
+SQLITE_PRIVATE const void *sqlite3BtreePayloadFetch(BtCursor*, u32 *pAmt);
+SQLITE_PRIVATE u32 sqlite3BtreePayloadSize(BtCursor*);
+SQLITE_PRIVATE int sqlite3BtreeData(BtCursor*, u32 offset, u32 amt, void*);
+
+SQLITE_PRIVATE char *sqlite3BtreeIntegrityCheck(Btree*, int *aRoot, int nRoot, int, int*);
+SQLITE_PRIVATE struct Pager *sqlite3BtreePager(Btree*);
+
+#ifndef SQLITE_OMIT_INCRBLOB
+SQLITE_PRIVATE int sqlite3BtreePutData(BtCursor*, u32 offset, u32 amt, void*);
+SQLITE_PRIVATE void sqlite3BtreeIncrblobCursor(BtCursor *);
+#endif
+SQLITE_PRIVATE void sqlite3BtreeClearCursor(BtCursor *);
+SQLITE_PRIVATE int sqlite3BtreeSetVersion(Btree *pBt, int iVersion);
+SQLITE_PRIVATE int sqlite3BtreeCursorHasHint(BtCursor*, unsigned int mask);
+SQLITE_PRIVATE int sqlite3BtreeIsReadonly(Btree *pBt);
+SQLITE_PRIVATE int sqlite3HeaderSizeBtree(void);
+
+#ifndef NDEBUG
+SQLITE_PRIVATE int sqlite3BtreeCursorIsValid(BtCursor*);
+#endif
+
+#ifndef SQLITE_OMIT_BTREECOUNT
+SQLITE_PRIVATE int sqlite3BtreeCount(BtCursor *, i64 *);
+#endif
+
+#ifdef SQLITE_TEST
+SQLITE_PRIVATE int sqlite3BtreeCursorInfo(BtCursor*, int*, int);
+SQLITE_PRIVATE void sqlite3BtreeCursorList(Btree*);
+#endif
+
+#ifndef SQLITE_OMIT_WAL
+SQLITE_PRIVATE   int sqlite3BtreeCheckpoint(Btree*, int, int *, int *);
+#endif
+
+/*
+** If we are not using shared cache, then there is no need to
+** use mutexes to access the BtShared structures.  So make the
+** Enter and Leave procedures no-ops.
+*/
+#ifndef SQLITE_OMIT_SHARED_CACHE
+SQLITE_PRIVATE   void sqlite3BtreeEnter(Btree*);
+SQLITE_PRIVATE   void sqlite3BtreeEnterAll(sqlite3*);
+SQLITE_PRIVATE   int sqlite3BtreeSharable(Btree*);
+SQLITE_PRIVATE   void sqlite3BtreeEnterCursor(BtCursor*);
+SQLITE_PRIVATE   int sqlite3BtreeConnectionCount(Btree*);
+#else
+# define sqlite3BtreeEnter(X) 
+# define sqlite3BtreeEnterAll(X)
+# define sqlite3BtreeSharable(X) 0
+# define sqlite3BtreeEnterCursor(X)
+# define sqlite3BtreeConnectionCount(X) 1
+#endif
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE
+SQLITE_PRIVATE   void sqlite3BtreeLeave(Btree*);
+SQLITE_PRIVATE   void sqlite3BtreeLeaveCursor(BtCursor*);
+SQLITE_PRIVATE   void sqlite3BtreeLeaveAll(sqlite3*);
+#ifndef NDEBUG
+  /* These routines are used inside assert() statements only. */
+SQLITE_PRIVATE   int sqlite3BtreeHoldsMutex(Btree*);
+SQLITE_PRIVATE   int sqlite3BtreeHoldsAllMutexes(sqlite3*);
+SQLITE_PRIVATE   int sqlite3SchemaMutexHeld(sqlite3*,int,Schema*);
+#endif
+#else
+
+# define sqlite3BtreeLeave(X)
+# define sqlite3BtreeLeaveCursor(X)
+# define sqlite3BtreeLeaveAll(X)
+
+# define sqlite3BtreeHoldsMutex(X) 1
+# define sqlite3BtreeHoldsAllMutexes(X) 1
+# define sqlite3SchemaMutexHeld(X,Y,Z) 1
+#endif
+
+
+#endif /* SQLITE_BTREE_H */
+
+/************** End of btree.h ***********************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+/************** Include vdbe.h in the middle of sqliteInt.h ******************/
+/************** Begin file vdbe.h ********************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** Header file for the Virtual DataBase Engine (VDBE)
+**
+** This header defines the interface to the virtual database engine
+** or VDBE.  The VDBE implements an abstract machine that runs a
+** simple program to access and modify the underlying database.
+*/
+#ifndef SQLITE_VDBE_H
+#define SQLITE_VDBE_H
+/* #include <stdio.h> */
+
+/*
+** A single VDBE is an opaque structure named "Vdbe".  Only routines
+** in the source file sqliteVdbe.c are allowed to see the insides
+** of this structure.
+*/
+typedef struct Vdbe Vdbe;
+
+/*
+** The names of the following types declared in vdbeInt.h are required
+** for the VdbeOp definition.
+*/
+typedef struct Mem Mem;
+typedef struct SubProgram SubProgram;
+
+/*
+** A single instruction of the virtual machine has an opcode
+** and as many as three operands.  The instruction is recorded
+** as an instance of the following structure:
+*/
+struct VdbeOp {
+  u8 opcode;          /* What operation to perform */
+  signed char p4type; /* One of the P4_xxx constants for p4 */
+  u8 notUsed1;
+  u8 p5;              /* Fifth parameter is an unsigned character */
+  int p1;             /* First operand */
+  int p2;             /* Second parameter (often the jump destination) */
+  int p3;             /* The third parameter */
+  union p4union {     /* fourth parameter */
+    int i;                 /* Integer value if p4type==P4_INT32 */
+    void *p;               /* Generic pointer */
+    char *z;               /* Pointer to data for string (char array) types */
+    i64 *pI64;             /* Used when p4type is P4_INT64 */
+    double *pReal;         /* Used when p4type is P4_REAL */
+    FuncDef *pFunc;        /* Used when p4type is P4_FUNCDEF */
+    sqlite3_context *pCtx; /* Used when p4type is P4_FUNCCTX */
+    CollSeq *pColl;        /* Used when p4type is P4_COLLSEQ */
+    Mem *pMem;             /* Used when p4type is P4_MEM */
+    VTable *pVtab;         /* Used when p4type is P4_VTAB */
+    KeyInfo *pKeyInfo;     /* Used when p4type is P4_KEYINFO */
+    int *ai;               /* Used when p4type is P4_INTARRAY */
+    SubProgram *pProgram;  /* Used when p4type is P4_SUBPROGRAM */
+    Table *pTab;           /* Used when p4type is P4_TABLE */
+#ifdef SQLITE_ENABLE_CURSOR_HINTS
+    Expr *pExpr;           /* Used when p4type is P4_EXPR */
+#endif
+    int (*xAdvance)(BtCursor *, int *);
+  } p4;
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+  char *zComment;          /* Comment to improve readability */
+#endif
+#ifdef VDBE_PROFILE
+  u32 cnt;                 /* Number of times this instruction was executed */
+  u64 cycles;              /* Total time spent executing this instruction */
+#endif
+#ifdef SQLITE_VDBE_COVERAGE
+  int iSrcLine;            /* Source-code line that generated this opcode */
+#endif
+};
+typedef struct VdbeOp VdbeOp;
+
+
+/*
+** A sub-routine used to implement a trigger program.
+*/
+struct SubProgram {
+  VdbeOp *aOp;                  /* Array of opcodes for sub-program */
+  int nOp;                      /* Elements in aOp[] */
+  int nMem;                     /* Number of memory cells required */
+  int nCsr;                     /* Number of cursors required */
+  void *token;                  /* id that may be used to recursive triggers */
+  SubProgram *pNext;            /* Next sub-program already visited */
+};
+
+/*
+** A smaller version of VdbeOp used for the VdbeAddOpList() function because
+** it takes up less space.
+*/
+struct VdbeOpList {
+  u8 opcode;          /* What operation to perform */
+  signed char p1;     /* First operand */
+  signed char p2;     /* Second parameter (often the jump destination) */
+  signed char p3;     /* Third parameter */
+};
+typedef struct VdbeOpList VdbeOpList;
+
+/*
+** Allowed values of VdbeOp.p4type
+*/
+#define P4_NOTUSED    0   /* The P4 parameter is not used */
+#define P4_DYNAMIC  (-1)  /* Pointer to a string obtained from sqliteMalloc() */
+#define P4_STATIC   (-2)  /* Pointer to a static string */
+#define P4_COLLSEQ  (-4)  /* P4 is a pointer to a CollSeq structure */
+#define P4_FUNCDEF  (-5)  /* P4 is a pointer to a FuncDef structure */
+#define P4_KEYINFO  (-6)  /* P4 is a pointer to a KeyInfo structure */
+#define P4_EXPR     (-7)  /* P4 is a pointer to an Expr tree */
+#define P4_MEM      (-8)  /* P4 is a pointer to a Mem*    structure */
+#define P4_TRANSIENT  0   /* P4 is a pointer to a transient string */
+#define P4_VTAB     (-10) /* P4 is a pointer to an sqlite3_vtab structure */
+#define P4_MPRINTF  (-11) /* P4 is a string obtained from sqlite3_mprintf() */
+#define P4_REAL     (-12) /* P4 is a 64-bit floating point value */
+#define P4_INT64    (-13) /* P4 is a 64-bit signed integer */
+#define P4_INT32    (-14) /* P4 is a 32-bit signed integer */
+#define P4_INTARRAY (-15) /* P4 is a vector of 32-bit integers */
+#define P4_SUBPROGRAM  (-18) /* P4 is a pointer to a SubProgram structure */
+#define P4_ADVANCE  (-19) /* P4 is a pointer to BtreeNext() or BtreePrev() */
+#define P4_TABLE    (-20) /* P4 is a pointer to a Table structure */
+#define P4_FUNCCTX  (-21) /* P4 is a pointer to an sqlite3_context object */
+
+/* Error message codes for OP_Halt */
+#define P5_ConstraintNotNull 1
+#define P5_ConstraintUnique  2
+#define P5_ConstraintCheck   3
+#define P5_ConstraintFK      4
+
+/*
+** The Vdbe.aColName array contains 5n Mem structures, where n is the 
+** number of columns of data returned by the statement.
+*/
+#define COLNAME_NAME     0
+#define COLNAME_DECLTYPE 1
+#define COLNAME_DATABASE 2
+#define COLNAME_TABLE    3
+#define COLNAME_COLUMN   4
+#ifdef SQLITE_ENABLE_COLUMN_METADATA
+# define COLNAME_N        5      /* Number of COLNAME_xxx symbols */
+#else
+# ifdef SQLITE_OMIT_DECLTYPE
+#   define COLNAME_N      1      /* Store only the name */
+# else
+#   define COLNAME_N      2      /* Store the name and decltype */
+# endif
+#endif
+
+/*
+** The following macro converts a relative address in the p2 field
+** of a VdbeOp structure into a negative number so that 
+** sqlite3VdbeAddOpList() knows that the address is relative.  Calling
+** the macro again restores the address.
+*/
+#define ADDR(X)  (-1-(X))
+
+/*
+** The makefile scans the vdbe.c source file and creates the "opcodes.h"
+** header file that defines a number for each opcode used by the VDBE.
+*/
+/************** Include opcodes.h in the middle of vdbe.h ********************/
+/************** Begin file opcodes.h *****************************************/
+/* Automatically generated.  Do not edit */
+/* See the tool/mkopcodeh.tcl script for details */
+#define OP_Savepoint       0
+#define OP_AutoCommit      1
+#define OP_Transaction     2
+#define OP_SorterNext      3
+#define OP_PrevIfOpen      4
+#define OP_NextIfOpen      5
+#define OP_Prev            6
+#define OP_Next            7
+#define OP_Checkpoint      8
+#define OP_JournalMode     9
+#define OP_Vacuum         10
+#define OP_VFilter        11 /* synopsis: iplan=r[P3] zplan='P4'           */
+#define OP_VUpdate        12 /* synopsis: data=r[P3@P2]                    */
+#define OP_Goto           13
+#define OP_Gosub          14
+#define OP_InitCoroutine  15
+#define OP_Yield          16
+#define OP_MustBeInt      17
+#define OP_Jump           18
+#define OP_Not            19 /* same as TK_NOT, synopsis: r[P2]= !r[P1]    */
+#define OP_Once           20
+#define OP_If             21
+#define OP_IfNot          22
+#define OP_SeekLT         23 /* synopsis: key=r[P3@P4]                     */
+#define OP_SeekLE         24 /* synopsis: key=r[P3@P4]                     */
+#define OP_SeekGE         25 /* synopsis: key=r[P3@P4]                     */
+#define OP_SeekGT         26 /* synopsis: key=r[P3@P4]                     */
+#define OP_Or             27 /* same as TK_OR, synopsis: r[P3]=(r[P1] || r[P2]) */
+#define OP_And            28 /* same as TK_AND, synopsis: r[P3]=(r[P1] && r[P2]) */
+#define OP_NoConflict     29 /* synopsis: key=r[P3@P4]                     */
+#define OP_NotFound       30 /* synopsis: key=r[P3@P4]                     */
+#define OP_Found          31 /* synopsis: key=r[P3@P4]                     */
+#define OP_SeekRowid      32 /* synopsis: intkey=r[P3]                     */
+#define OP_NotExists      33 /* synopsis: intkey=r[P3]                     */
+#define OP_IsNull         34 /* same as TK_ISNULL, synopsis: if r[P1]==NULL goto P2 */
+#define OP_NotNull        35 /* same as TK_NOTNULL, synopsis: if r[P1]!=NULL goto P2 */
+#define OP_Ne             36 /* same as TK_NE, synopsis: IF r[P3]!=r[P1]   */
+#define OP_Eq             37 /* same as TK_EQ, synopsis: IF r[P3]==r[P1]   */
+#define OP_Gt             38 /* same as TK_GT, synopsis: IF r[P3]>r[P1]    */
+#define OP_Le             39 /* same as TK_LE, synopsis: IF r[P3]<=r[P1]   */
+#define OP_Lt             40 /* same as TK_LT, synopsis: IF r[P3]<r[P1]    */
+#define OP_Ge             41 /* same as TK_GE, synopsis: IF r[P3]>=r[P1]   */
+#define OP_ElseNotEq      42 /* same as TK_ESCAPE                          */
+#define OP_BitAnd         43 /* same as TK_BITAND, synopsis: r[P3]=r[P1]&r[P2] */
+#define OP_BitOr          44 /* same as TK_BITOR, synopsis: r[P3]=r[P1]|r[P2] */
+#define OP_ShiftLeft      45 /* same as TK_LSHIFT, synopsis: r[P3]=r[P2]<<r[P1] */
+#define OP_ShiftRight     46 /* same as TK_RSHIFT, synopsis: r[P3]=r[P2]>>r[P1] */
+#define OP_Add            47 /* same as TK_PLUS, synopsis: r[P3]=r[P1]+r[P2] */
+#define OP_Subtract       48 /* same as TK_MINUS, synopsis: r[P3]=r[P2]-r[P1] */
+#define OP_Multiply       49 /* same as TK_STAR, synopsis: r[P3]=r[P1]*r[P2] */
+#define OP_Divide         50 /* same as TK_SLASH, synopsis: r[P3]=r[P2]/r[P1] */
+#define OP_Remainder      51 /* same as TK_REM, synopsis: r[P3]=r[P2]%r[P1] */
+#define OP_Concat         52 /* same as TK_CONCAT, synopsis: r[P3]=r[P2]+r[P1] */
+#define OP_Last           53
+#define OP_BitNot         54 /* same as TK_BITNOT, synopsis: r[P1]= ~r[P1] */
+#define OP_SorterSort     55
+#define OP_Sort           56
+#define OP_Rewind         57
+#define OP_IdxLE          58 /* synopsis: key=r[P3@P4]                     */
+#define OP_IdxGT          59 /* synopsis: key=r[P3@P4]                     */
+#define OP_IdxLT          60 /* synopsis: key=r[P3@P4]                     */
+#define OP_IdxGE          61 /* synopsis: key=r[P3@P4]                     */
+#define OP_RowSetRead     62 /* synopsis: r[P3]=rowset(P1)                 */
+#define OP_RowSetTest     63 /* synopsis: if r[P3] in rowset(P1) goto P2   */
+#define OP_Program        64
+#define OP_FkIfZero       65 /* synopsis: if fkctr[P1]==0 goto P2          */
+#define OP_IfPos          66 /* synopsis: if r[P1]>0 then r[P1]-=P3, goto P2 */
+#define OP_IfNotZero      67 /* synopsis: if r[P1]!=0 then r[P1]-=P3, goto P2 */
+#define OP_DecrJumpZero   68 /* synopsis: if (--r[P1])==0 goto P2          */
+#define OP_IncrVacuum     69
+#define OP_VNext          70
+#define OP_Init           71 /* synopsis: Start at P2                      */
+#define OP_Return         72
+#define OP_EndCoroutine   73
+#define OP_HaltIfNull     74 /* synopsis: if r[P3]=null halt               */
+#define OP_Halt           75
+#define OP_Integer        76 /* synopsis: r[P2]=P1                         */
+#define OP_Int64          77 /* synopsis: r[P2]=P4                         */
+#define OP_String         78 /* synopsis: r[P2]='P4' (len=P1)              */
+#define OP_Null           79 /* synopsis: r[P2..P3]=NULL                   */
+#define OP_SoftNull       80 /* synopsis: r[P1]=NULL                       */
+#define OP_Blob           81 /* synopsis: r[P2]=P4 (len=P1)                */
+#define OP_Variable       82 /* synopsis: r[P2]=parameter(P1,P4)           */
+#define OP_Move           83 /* synopsis: r[P2@P3]=r[P1@P3]                */
+#define OP_Copy           84 /* synopsis: r[P2@P3+1]=r[P1@P3+1]            */
+#define OP_SCopy          85 /* synopsis: r[P2]=r[P1]                      */
+#define OP_IntCopy        86 /* synopsis: r[P2]=r[P1]                      */
+#define OP_ResultRow      87 /* synopsis: output=r[P1@P2]                  */
+#define OP_CollSeq        88
+#define OP_Function0      89 /* synopsis: r[P3]=func(r[P2@P5])             */
+#define OP_Function       90 /* synopsis: r[P3]=func(r[P2@P5])             */
+#define OP_AddImm         91 /* synopsis: r[P1]=r[P1]+P2                   */
+#define OP_RealAffinity   92
+#define OP_Cast           93 /* synopsis: affinity(r[P1])                  */
+#define OP_Permutation    94
+#define OP_Compare        95 /* synopsis: r[P1@P3] <-> r[P2@P3]            */
+#define OP_Column         96 /* synopsis: r[P3]=PX                         */
+#define OP_String8        97 /* same as TK_STRING, synopsis: r[P2]='P4'    */
+#define OP_Affinity       98 /* synopsis: affinity(r[P1@P2])               */
+#define OP_MakeRecord     99 /* synopsis: r[P3]=mkrec(r[P1@P2])            */
+#define OP_Count         100 /* synopsis: r[P2]=count()                    */
+#define OP_ReadCookie    101
+#define OP_SetCookie     102
+#define OP_ReopenIdx     103 /* synopsis: root=P2 iDb=P3                   */
+#define OP_OpenRead      104 /* synopsis: root=P2 iDb=P3                   */
+#define OP_OpenWrite     105 /* synopsis: root=P2 iDb=P3                   */
+#define OP_OpenAutoindex 106 /* synopsis: nColumn=P2                       */
+#define OP_OpenEphemeral 107 /* synopsis: nColumn=P2                       */
+#define OP_SorterOpen    108
+#define OP_SequenceTest  109 /* synopsis: if( cursor[P1].ctr++ ) pc = P2   */
+#define OP_OpenPseudo    110 /* synopsis: P3 columns in r[P2]              */
+#define OP_Close         111
+#define OP_ColumnsUsed   112
+#define OP_Sequence      113 /* synopsis: r[P2]=cursor[P1].ctr++           */
+#define OP_NewRowid      114 /* synopsis: r[P2]=rowid                      */
+#define OP_Insert        115 /* synopsis: intkey=r[P3] data=r[P2]          */
+#define OP_InsertInt     116 /* synopsis: intkey=P3 data=r[P2]             */
+#define OP_Delete        117
+#define OP_ResetCount    118
+#define OP_SorterCompare 119 /* synopsis: if key(P1)!=trim(r[P3],P4) goto P2 */
+#define OP_SorterData    120 /* synopsis: r[P2]=data                       */
+#define OP_RowKey        121 /* synopsis: r[P2]=key                        */
+#define OP_RowData       122 /* synopsis: r[P2]=data                       */
+#define OP_Rowid         123 /* synopsis: r[P2]=rowid                      */
+#define OP_NullRow       124
+#define OP_SorterInsert  125
+#define OP_IdxInsert     126 /* synopsis: key=r[P2]                        */
+#define OP_IdxDelete     127 /* synopsis: key=r[P2@P3]                     */
+#define OP_Seek          128 /* synopsis: Move P3 to P1.rowid              */
+#define OP_IdxRowid      129 /* synopsis: r[P2]=rowid                      */
+#define OP_Destroy       130
+#define OP_Clear         131
+#define OP_Real          132 /* same as TK_FLOAT, synopsis: r[P2]=P4       */
+#define OP_ResetSorter   133
+#define OP_CreateIndex   134 /* synopsis: r[P2]=root iDb=P1                */
+#define OP_CreateTable   135 /* synopsis: r[P2]=root iDb=P1                */
+#define OP_ParseSchema   136
+#define OP_LoadAnalysis  137
+#define OP_DropTable     138
+#define OP_DropIndex     139
+#define OP_DropTrigger   140
+#define OP_IntegrityCk   141
+#define OP_RowSetAdd     142 /* synopsis: rowset(P1)=r[P2]                 */
+#define OP_Param         143
+#define OP_FkCounter     144 /* synopsis: fkctr[P1]+=P2                    */
+#define OP_MemMax        145 /* synopsis: r[P1]=max(r[P1],r[P2])           */
+#define OP_OffsetLimit   146 /* synopsis: if r[P1]>0 then r[P2]=r[P1]+max(0,r[P3]) else r[P2]=(-1) */
+#define OP_AggStep0      147 /* synopsis: accum=r[P3] step(r[P2@P5])       */
+#define OP_AggStep       148 /* synopsis: accum=r[P3] step(r[P2@P5])       */
+#define OP_AggFinal      149 /* synopsis: accum=r[P1] N=P2                 */
+#define OP_Expire        150
+#define OP_TableLock     151 /* synopsis: iDb=P1 root=P2 write=P3          */
+#define OP_VBegin        152
+#define OP_VCreate       153
+#define OP_VDestroy      154
+#define OP_VOpen         155
+#define OP_VColumn       156 /* synopsis: r[P3]=vcolumn(P2)                */
+#define OP_VRename       157
+#define OP_Pagecount     158
+#define OP_MaxPgcnt      159
+#define OP_CursorHint    160
+#define OP_Noop          161
+#define OP_Explain       162
+
+/* Properties such as "out2" or "jump" that are specified in
+** comments following the "case" for each opcode in the vdbe.c
+** are encoded into bitvectors as follows:
+*/
+#define OPFLG_JUMP        0x01  /* jump:  P2 holds jmp target */
+#define OPFLG_IN1         0x02  /* in1:   P1 is an input */
+#define OPFLG_IN2         0x04  /* in2:   P2 is an input */
+#define OPFLG_IN3         0x08  /* in3:   P3 is an input */
+#define OPFLG_OUT2        0x10  /* out2:  P2 is an output */
+#define OPFLG_OUT3        0x20  /* out3:  P3 is an output */
+#define OPFLG_INITIALIZER {\
+/*   0 */ 0x00, 0x00, 0x00, 0x01, 0x01, 0x01, 0x01, 0x01,\
+/*   8 */ 0x00, 0x10, 0x00, 0x01, 0x00, 0x01, 0x01, 0x01,\
+/*  16 */ 0x03, 0x03, 0x01, 0x12, 0x01, 0x03, 0x03, 0x09,\
+/*  24 */ 0x09, 0x09, 0x09, 0x26, 0x26, 0x09, 0x09, 0x09,\
+/*  32 */ 0x09, 0x09, 0x03, 0x03, 0x0b, 0x0b, 0x0b, 0x0b,\
+/*  40 */ 0x0b, 0x0b, 0x01, 0x26, 0x26, 0x26, 0x26, 0x26,\
+/*  48 */ 0x26, 0x26, 0x26, 0x26, 0x26, 0x01, 0x12, 0x01,\
+/*  56 */ 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x23, 0x0b,\
+/*  64 */ 0x01, 0x01, 0x03, 0x03, 0x03, 0x01, 0x01, 0x01,\
+/*  72 */ 0x02, 0x02, 0x08, 0x00, 0x10, 0x10, 0x10, 0x10,\
+/*  80 */ 0x00, 0x10, 0x10, 0x00, 0x00, 0x10, 0x10, 0x00,\
+/*  88 */ 0x00, 0x00, 0x00, 0x02, 0x02, 0x02, 0x00, 0x00,\
+/*  96 */ 0x00, 0x10, 0x00, 0x00, 0x10, 0x10, 0x00, 0x00,\
+/* 104 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,\
+/* 112 */ 0x00, 0x10, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00,\
+/* 120 */ 0x00, 0x00, 0x00, 0x10, 0x00, 0x04, 0x04, 0x00,\
+/* 128 */ 0x00, 0x10, 0x10, 0x00, 0x10, 0x00, 0x10, 0x10,\
+/* 136 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x06, 0x10,\
+/* 144 */ 0x00, 0x04, 0x1a, 0x00, 0x00, 0x00, 0x00, 0x00,\
+/* 152 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x10,\
+/* 160 */ 0x00, 0x00, 0x00,}
+
+/* The sqlite3P2Values() routine is able to run faster if it knows
+** the value of the largest JUMP opcode.  The smaller the maximum
+** JUMP opcode the better, so the mkopcodeh.tcl script that
+** generated this include file strives to group all JUMP opcodes
+** together near the beginning of the list.
+*/
+#define SQLITE_MX_JUMP_OPCODE  71  /* Maximum JUMP opcode */
+
+/************** End of opcodes.h *********************************************/
+/************** Continuing where we left off in vdbe.h ***********************/
+
+/*
+** Prototypes for the VDBE interface.  See comments on the implementation
+** for a description of what each of these routines does.
+*/
+SQLITE_PRIVATE Vdbe *sqlite3VdbeCreate(Parse*);
+SQLITE_PRIVATE int sqlite3VdbeAddOp0(Vdbe*,int);
+SQLITE_PRIVATE int sqlite3VdbeAddOp1(Vdbe*,int,int);
+SQLITE_PRIVATE int sqlite3VdbeAddOp2(Vdbe*,int,int,int);
+SQLITE_PRIVATE int sqlite3VdbeGoto(Vdbe*,int);
+SQLITE_PRIVATE int sqlite3VdbeLoadString(Vdbe*,int,const char*);
+SQLITE_PRIVATE void sqlite3VdbeMultiLoad(Vdbe*,int,const char*,...);
+SQLITE_PRIVATE int sqlite3VdbeAddOp3(Vdbe*,int,int,int,int);
+SQLITE_PRIVATE int sqlite3VdbeAddOp4(Vdbe*,int,int,int,int,const char *zP4,int);
+SQLITE_PRIVATE int sqlite3VdbeAddOp4Dup8(Vdbe*,int,int,int,int,const u8*,int);
+SQLITE_PRIVATE int sqlite3VdbeAddOp4Int(Vdbe*,int,int,int,int,int);
+SQLITE_PRIVATE void sqlite3VdbeEndCoroutine(Vdbe*,int);
+#if defined(SQLITE_DEBUG) && !defined(SQLITE_TEST_REALLOC_STRESS)
+SQLITE_PRIVATE   void sqlite3VdbeVerifyNoMallocRequired(Vdbe *p, int N);
+#else
+# define sqlite3VdbeVerifyNoMallocRequired(A,B)
+#endif
+SQLITE_PRIVATE VdbeOp *sqlite3VdbeAddOpList(Vdbe*, int nOp, VdbeOpList const *aOp, int iLineno);
+SQLITE_PRIVATE void sqlite3VdbeAddParseSchemaOp(Vdbe*,int,char*);
+SQLITE_PRIVATE void sqlite3VdbeChangeOpcode(Vdbe*, u32 addr, u8);
+SQLITE_PRIVATE void sqlite3VdbeChangeP1(Vdbe*, u32 addr, int P1);
+SQLITE_PRIVATE void sqlite3VdbeChangeP2(Vdbe*, u32 addr, int P2);
+SQLITE_PRIVATE void sqlite3VdbeChangeP3(Vdbe*, u32 addr, int P3);
+SQLITE_PRIVATE void sqlite3VdbeChangeP5(Vdbe*, u8 P5);
+SQLITE_PRIVATE void sqlite3VdbeJumpHere(Vdbe*, int addr);
+SQLITE_PRIVATE int sqlite3VdbeChangeToNoop(Vdbe*, int addr);
+SQLITE_PRIVATE int sqlite3VdbeDeletePriorOpcode(Vdbe*, u8 op);
+SQLITE_PRIVATE void sqlite3VdbeChangeP4(Vdbe*, int addr, const char *zP4, int N);
+SQLITE_PRIVATE void sqlite3VdbeSetP4KeyInfo(Parse*, Index*);
+SQLITE_PRIVATE void sqlite3VdbeUsesBtree(Vdbe*, int);
+SQLITE_PRIVATE VdbeOp *sqlite3VdbeGetOp(Vdbe*, int);
+SQLITE_PRIVATE int sqlite3VdbeMakeLabel(Vdbe*);
+SQLITE_PRIVATE void sqlite3VdbeRunOnlyOnce(Vdbe*);
+SQLITE_PRIVATE void sqlite3VdbeReusable(Vdbe*);
+SQLITE_PRIVATE void sqlite3VdbeDelete(Vdbe*);
+SQLITE_PRIVATE void sqlite3VdbeClearObject(sqlite3*,Vdbe*);
+SQLITE_PRIVATE void sqlite3VdbeMakeReady(Vdbe*,Parse*);
+SQLITE_PRIVATE int sqlite3VdbeFinalize(Vdbe*);
+SQLITE_PRIVATE void sqlite3VdbeResolveLabel(Vdbe*, int);
+SQLITE_PRIVATE int sqlite3VdbeCurrentAddr(Vdbe*);
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE   int sqlite3VdbeAssertMayAbort(Vdbe *, int);
+#endif
+SQLITE_PRIVATE void sqlite3VdbeResetStepResult(Vdbe*);
+SQLITE_PRIVATE void sqlite3VdbeRewind(Vdbe*);
+SQLITE_PRIVATE int sqlite3VdbeReset(Vdbe*);
+SQLITE_PRIVATE void sqlite3VdbeSetNumCols(Vdbe*,int);
+SQLITE_PRIVATE int sqlite3VdbeSetColName(Vdbe*, int, int, const char *, void(*)(void*));
+SQLITE_PRIVATE void sqlite3VdbeCountChanges(Vdbe*);
+SQLITE_PRIVATE sqlite3 *sqlite3VdbeDb(Vdbe*);
+SQLITE_PRIVATE void sqlite3VdbeSetSql(Vdbe*, const char *z, int n, int);
+SQLITE_PRIVATE void sqlite3VdbeSwap(Vdbe*,Vdbe*);
+SQLITE_PRIVATE VdbeOp *sqlite3VdbeTakeOpArray(Vdbe*, int*, int*);
+SQLITE_PRIVATE sqlite3_value *sqlite3VdbeGetBoundValue(Vdbe*, int, u8);
+SQLITE_PRIVATE void sqlite3VdbeSetVarmask(Vdbe*, int);
+#ifndef SQLITE_OMIT_TRACE
+SQLITE_PRIVATE   char *sqlite3VdbeExpandSql(Vdbe*, const char*);
+#endif
+SQLITE_PRIVATE int sqlite3MemCompare(const Mem*, const Mem*, const CollSeq*);
+
+SQLITE_PRIVATE void sqlite3VdbeRecordUnpack(KeyInfo*,int,const void*,UnpackedRecord*);
+SQLITE_PRIVATE int sqlite3VdbeRecordCompare(int,const void*,UnpackedRecord*);
+SQLITE_PRIVATE int sqlite3VdbeRecordCompareWithSkip(int, const void *, UnpackedRecord *, int);
+SQLITE_PRIVATE UnpackedRecord *sqlite3VdbeAllocUnpackedRecord(KeyInfo *, char *, int, char **);
+
+typedef int (*RecordCompare)(int,const void*,UnpackedRecord*);
+SQLITE_PRIVATE RecordCompare sqlite3VdbeFindCompare(UnpackedRecord*);
+
+#ifndef SQLITE_OMIT_TRIGGER
+SQLITE_PRIVATE void sqlite3VdbeLinkSubProgram(Vdbe *, SubProgram *);
+#endif
+
+/* Use SQLITE_ENABLE_COMMENTS to enable generation of extra comments on
+** each VDBE opcode.
+**
+** Use the SQLITE_ENABLE_MODULE_COMMENTS macro to see some extra no-op
+** comments in VDBE programs that show key decision points in the code
+** generator.
+*/
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+SQLITE_PRIVATE   void sqlite3VdbeComment(Vdbe*, const char*, ...);
+# define VdbeComment(X)  sqlite3VdbeComment X
+SQLITE_PRIVATE   void sqlite3VdbeNoopComment(Vdbe*, const char*, ...);
+# define VdbeNoopComment(X)  sqlite3VdbeNoopComment X
+# ifdef SQLITE_ENABLE_MODULE_COMMENTS
+#   define VdbeModuleComment(X)  sqlite3VdbeNoopComment X
+# else
+#   define VdbeModuleComment(X)
+# endif
+#else
+# define VdbeComment(X)
+# define VdbeNoopComment(X)
+# define VdbeModuleComment(X)
+#endif
+
+/*
+** The VdbeCoverage macros are used to set a coverage testing point
+** for VDBE branch instructions.  The coverage testing points are line
+** numbers in the sqlite3.c source file.  VDBE branch coverage testing
+** only works with an amalagmation build.  That's ok since a VDBE branch
+** coverage build designed for testing the test suite only.  No application
+** should ever ship with VDBE branch coverage measuring turned on.
+**
+**    VdbeCoverage(v)                  // Mark the previously coded instruction
+**                                     // as a branch
+**
+**    VdbeCoverageIf(v, conditional)   // Mark previous if conditional true
+**
+**    VdbeCoverageAlwaysTaken(v)       // Previous branch is always taken
+**
+**    VdbeCoverageNeverTaken(v)        // Previous branch is never taken
+**
+** Every VDBE branch operation must be tagged with one of the macros above.
+** If not, then when "make test" is run with -DSQLITE_VDBE_COVERAGE and
+** -DSQLITE_DEBUG then an ALWAYS() will fail in the vdbeTakeBranch()
+** routine in vdbe.c, alerting the developer to the missed tag.
+*/
+#ifdef SQLITE_VDBE_COVERAGE
+SQLITE_PRIVATE   void sqlite3VdbeSetLineNumber(Vdbe*,int);
+# define VdbeCoverage(v) sqlite3VdbeSetLineNumber(v,__LINE__)
+# define VdbeCoverageIf(v,x) if(x)sqlite3VdbeSetLineNumber(v,__LINE__)
+# define VdbeCoverageAlwaysTaken(v) sqlite3VdbeSetLineNumber(v,2);
+# define VdbeCoverageNeverTaken(v) sqlite3VdbeSetLineNumber(v,1);
+# define VDBE_OFFSET_LINENO(x) (__LINE__+x)
+#else
+# define VdbeCoverage(v)
+# define VdbeCoverageIf(v,x)
+# define VdbeCoverageAlwaysTaken(v)
+# define VdbeCoverageNeverTaken(v)
+# define VDBE_OFFSET_LINENO(x) 0
+#endif
+
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+SQLITE_PRIVATE void sqlite3VdbeScanStatus(Vdbe*, int, int, int, LogEst, const char*);
+#else
+# define sqlite3VdbeScanStatus(a,b,c,d,e)
+#endif
+
+#endif /* SQLITE_VDBE_H */
+
+/************** End of vdbe.h ************************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+/************** Include pager.h in the middle of sqliteInt.h *****************/
+/************** Begin file pager.h *******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This header file defines the interface that the sqlite page cache
+** subsystem.  The page cache subsystem reads and writes a file a page
+** at a time and provides a journal for rollback.
+*/
+
+#ifndef SQLITE_PAGER_H
+#define SQLITE_PAGER_H
+
+/*
+** Default maximum size for persistent journal files. A negative 
+** value means no limit. This value may be overridden using the 
+** sqlite3PagerJournalSizeLimit() API. See also "PRAGMA journal_size_limit".
+*/
+#ifndef SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT
+  #define SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT -1
+#endif
+
+/*
+** The type used to represent a page number.  The first page in a file
+** is called page 1.  0 is used to represent "not a page".
+*/
+typedef u32 Pgno;
+
+/*
+** Each open file is managed by a separate instance of the "Pager" structure.
+*/
+typedef struct Pager Pager;
+
+/*
+** Handle type for pages.
+*/
+typedef struct PgHdr DbPage;
+
+/*
+** Page number PAGER_MJ_PGNO is never used in an SQLite database (it is
+** reserved for working around a windows/posix incompatibility). It is
+** used in the journal to signify that the remainder of the journal file 
+** is devoted to storing a master journal name - there are no more pages to
+** roll back. See comments for function writeMasterJournal() in pager.c 
+** for details.
+*/
+#define PAGER_MJ_PGNO(x) ((Pgno)((PENDING_BYTE/((x)->pageSize))+1))
+
+/*
+** Allowed values for the flags parameter to sqlite3PagerOpen().
+**
+** NOTE: These values must match the corresponding BTREE_ values in btree.h.
+*/
+#define PAGER_OMIT_JOURNAL  0x0001    /* Do not use a rollback journal */
+#define PAGER_MEMORY        0x0002    /* In-memory database */
+
+/*
+** Valid values for the second argument to sqlite3PagerLockingMode().
+*/
+#define PAGER_LOCKINGMODE_QUERY      -1
+#define PAGER_LOCKINGMODE_NORMAL      0
+#define PAGER_LOCKINGMODE_EXCLUSIVE   1
+
+/*
+** Numeric constants that encode the journalmode.
+**
+** The numeric values encoded here (other than PAGER_JOURNALMODE_QUERY)
+** are exposed in the API via the "PRAGMA journal_mode" command and
+** therefore cannot be changed without a compatibility break.
+*/
+#define PAGER_JOURNALMODE_QUERY     (-1)  /* Query the value of journalmode */
+#define PAGER_JOURNALMODE_DELETE      0   /* Commit by deleting journal file */
+#define PAGER_JOURNALMODE_PERSIST     1   /* Commit by zeroing journal header */
+#define PAGER_JOURNALMODE_OFF         2   /* Journal omitted.  */
+#define PAGER_JOURNALMODE_TRUNCATE    3   /* Commit by truncating journal */
+#define PAGER_JOURNALMODE_MEMORY      4   /* In-memory journal file */
+#define PAGER_JOURNALMODE_WAL         5   /* Use write-ahead logging */
+
+/*
+** Flags that make up the mask passed to sqlite3PagerGet().
+*/
+#define PAGER_GET_NOCONTENT     0x01  /* Do not load data from disk */
+#define PAGER_GET_READONLY      0x02  /* Read-only page is acceptable */
+
+/*
+** Flags for sqlite3PagerSetFlags()
+**
+** Value constraints (enforced via assert()):
+**    PAGER_FULLFSYNC      == SQLITE_FullFSync
+**    PAGER_CKPT_FULLFSYNC == SQLITE_CkptFullFSync
+**    PAGER_CACHE_SPILL    == SQLITE_CacheSpill
+*/
+#define PAGER_SYNCHRONOUS_OFF       0x01  /* PRAGMA synchronous=OFF */
+#define PAGER_SYNCHRONOUS_NORMAL    0x02  /* PRAGMA synchronous=NORMAL */
+#define PAGER_SYNCHRONOUS_FULL      0x03  /* PRAGMA synchronous=FULL */
+#define PAGER_SYNCHRONOUS_EXTRA     0x04  /* PRAGMA synchronous=EXTRA */
+#define PAGER_SYNCHRONOUS_MASK      0x07  /* Mask for four values above */
+#define PAGER_FULLFSYNC             0x08  /* PRAGMA fullfsync=ON */
+#define PAGER_CKPT_FULLFSYNC        0x10  /* PRAGMA checkpoint_fullfsync=ON */
+#define PAGER_CACHESPILL            0x20  /* PRAGMA cache_spill=ON */
+#define PAGER_FLAGS_MASK            0x38  /* All above except SYNCHRONOUS */
+
+/*
+** The remainder of this file contains the declarations of the functions
+** that make up the Pager sub-system API. See source code comments for 
+** a detailed description of each routine.
+*/
+
+/* Open and close a Pager connection. */ 
+SQLITE_PRIVATE int sqlite3PagerOpen(
+  sqlite3_vfs*,
+  Pager **ppPager,
+  const char*,
+  int,
+  int,
+  int,
+  void(*)(DbPage*)
+);
+SQLITE_PRIVATE int sqlite3PagerClose(Pager *pPager);
+SQLITE_PRIVATE int sqlite3PagerReadFileheader(Pager*, int, unsigned char*);
+
+/* Functions used to configure a Pager object. */
+SQLITE_PRIVATE void sqlite3PagerSetBusyhandler(Pager*, int(*)(void *), void *);
+SQLITE_PRIVATE int sqlite3PagerSetPagesize(Pager*, u32*, int);
+#ifdef SQLITE_HAS_CODEC
+SQLITE_PRIVATE void sqlite3PagerAlignReserve(Pager*,Pager*);
+#endif
+SQLITE_PRIVATE int sqlite3PagerMaxPageCount(Pager*, int);
+SQLITE_PRIVATE void sqlite3PagerSetCachesize(Pager*, int);
+SQLITE_PRIVATE int sqlite3PagerSetSpillsize(Pager*, int);
+SQLITE_PRIVATE void sqlite3PagerSetMmapLimit(Pager *, sqlite3_int64);
+SQLITE_PRIVATE void sqlite3PagerShrink(Pager*);
+SQLITE_PRIVATE void sqlite3PagerSetFlags(Pager*,unsigned);
+SQLITE_PRIVATE int sqlite3PagerLockingMode(Pager *, int);
+SQLITE_PRIVATE int sqlite3PagerSetJournalMode(Pager *, int);
+SQLITE_PRIVATE int sqlite3PagerGetJournalMode(Pager*);
+SQLITE_PRIVATE int sqlite3PagerOkToChangeJournalMode(Pager*);
+SQLITE_PRIVATE i64 sqlite3PagerJournalSizeLimit(Pager *, i64);
+SQLITE_PRIVATE sqlite3_backup **sqlite3PagerBackupPtr(Pager*);
+SQLITE_PRIVATE int sqlite3PagerFlush(Pager*);
+
+/* Functions used to obtain and release page references. */ 
+SQLITE_PRIVATE int sqlite3PagerGet(Pager *pPager, Pgno pgno, DbPage **ppPage, int clrFlag);
+SQLITE_PRIVATE DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno);
+SQLITE_PRIVATE void sqlite3PagerRef(DbPage*);
+SQLITE_PRIVATE void sqlite3PagerUnref(DbPage*);
+SQLITE_PRIVATE void sqlite3PagerUnrefNotNull(DbPage*);
+
+/* Operations on page references. */
+SQLITE_PRIVATE int sqlite3PagerWrite(DbPage*);
+SQLITE_PRIVATE void sqlite3PagerDontWrite(DbPage*);
+SQLITE_PRIVATE int sqlite3PagerMovepage(Pager*,DbPage*,Pgno,int);
+SQLITE_PRIVATE int sqlite3PagerPageRefcount(DbPage*);
+SQLITE_PRIVATE void *sqlite3PagerGetData(DbPage *); 
+SQLITE_PRIVATE void *sqlite3PagerGetExtra(DbPage *); 
+
+/* Functions used to manage pager transactions and savepoints. */
+SQLITE_PRIVATE void sqlite3PagerPagecount(Pager*, int*);
+SQLITE_PRIVATE int sqlite3PagerBegin(Pager*, int exFlag, int);
+SQLITE_PRIVATE int sqlite3PagerCommitPhaseOne(Pager*,const char *zMaster, int);
+SQLITE_PRIVATE int sqlite3PagerExclusiveLock(Pager*);
+SQLITE_PRIVATE int sqlite3PagerSync(Pager *pPager, const char *zMaster);
+SQLITE_PRIVATE int sqlite3PagerCommitPhaseTwo(Pager*);
+SQLITE_PRIVATE int sqlite3PagerRollback(Pager*);
+SQLITE_PRIVATE int sqlite3PagerOpenSavepoint(Pager *pPager, int n);
+SQLITE_PRIVATE int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint);
+SQLITE_PRIVATE int sqlite3PagerSharedLock(Pager *pPager);
+
+#ifndef SQLITE_OMIT_WAL
+SQLITE_PRIVATE   int sqlite3PagerCheckpoint(Pager *pPager, int, int*, int*);
+SQLITE_PRIVATE   int sqlite3PagerWalSupported(Pager *pPager);
+SQLITE_PRIVATE   int sqlite3PagerWalCallback(Pager *pPager);
+SQLITE_PRIVATE   int sqlite3PagerOpenWal(Pager *pPager, int *pisOpen);
+SQLITE_PRIVATE   int sqlite3PagerCloseWal(Pager *pPager);
+SQLITE_PRIVATE   int sqlite3PagerUseWal(Pager *pPager);
+# ifdef SQLITE_ENABLE_SNAPSHOT
+SQLITE_PRIVATE   int sqlite3PagerSnapshotGet(Pager *pPager, sqlite3_snapshot **ppSnapshot);
+SQLITE_PRIVATE   int sqlite3PagerSnapshotOpen(Pager *pPager, sqlite3_snapshot *pSnapshot);
+# endif
+#else
+# define sqlite3PagerUseWal(x) 0
+#endif
+
+#ifdef SQLITE_ENABLE_ZIPVFS
+SQLITE_PRIVATE   int sqlite3PagerWalFramesize(Pager *pPager);
+#endif
+
+/* Functions used to query pager state and configuration. */
+SQLITE_PRIVATE u8 sqlite3PagerIsreadonly(Pager*);
+SQLITE_PRIVATE u32 sqlite3PagerDataVersion(Pager*);
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE   int sqlite3PagerRefcount(Pager*);
+#endif
+SQLITE_PRIVATE int sqlite3PagerMemUsed(Pager*);
+SQLITE_PRIVATE const char *sqlite3PagerFilename(Pager*, int);
+SQLITE_PRIVATE sqlite3_vfs *sqlite3PagerVfs(Pager*);
+SQLITE_PRIVATE sqlite3_file *sqlite3PagerFile(Pager*);
+SQLITE_PRIVATE sqlite3_file *sqlite3PagerJrnlFile(Pager*);
+SQLITE_PRIVATE const char *sqlite3PagerJournalname(Pager*);
+SQLITE_PRIVATE void *sqlite3PagerTempSpace(Pager*);
+SQLITE_PRIVATE int sqlite3PagerIsMemdb(Pager*);
+SQLITE_PRIVATE void sqlite3PagerCacheStat(Pager *, int, int, int *);
+SQLITE_PRIVATE void sqlite3PagerClearCache(Pager*);
+SQLITE_PRIVATE int sqlite3SectorSize(sqlite3_file *);
+
+/* Functions used to truncate the database file. */
+SQLITE_PRIVATE void sqlite3PagerTruncateImage(Pager*,Pgno);
+
+SQLITE_PRIVATE void sqlite3PagerRekey(DbPage*, Pgno, u16);
+
+#if defined(SQLITE_HAS_CODEC) && !defined(SQLITE_OMIT_WAL)
+SQLITE_PRIVATE void *sqlite3PagerCodec(DbPage *);
+#endif
+
+/* Functions to support testing and debugging. */
+#if !defined(NDEBUG) || defined(SQLITE_TEST)
+SQLITE_PRIVATE   Pgno sqlite3PagerPagenumber(DbPage*);
+SQLITE_PRIVATE   int sqlite3PagerIswriteable(DbPage*);
+#endif
+#ifdef SQLITE_TEST
+SQLITE_PRIVATE   int *sqlite3PagerStats(Pager*);
+SQLITE_PRIVATE   void sqlite3PagerRefdump(Pager*);
+  void disable_simulated_io_errors(void);
+  void enable_simulated_io_errors(void);
+#else
+# define disable_simulated_io_errors()
+# define enable_simulated_io_errors()
+#endif
+
+#endif /* SQLITE_PAGER_H */
+
+/************** End of pager.h ***********************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+/************** Include pcache.h in the middle of sqliteInt.h ****************/
+/************** Begin file pcache.h ******************************************/
+/*
+** 2008 August 05
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This header file defines the interface that the sqlite page cache
+** subsystem. 
+*/
+
+#ifndef _PCACHE_H_
+
+typedef struct PgHdr PgHdr;
+typedef struct PCache PCache;
+
+/*
+** Every page in the cache is controlled by an instance of the following
+** structure.
+*/
+struct PgHdr {
+  sqlite3_pcache_page *pPage;    /* Pcache object page handle */
+  void *pData;                   /* Page data */
+  void *pExtra;                  /* Extra content */
+  PgHdr *pDirty;                 /* Transient list of dirty sorted by pgno */
+  Pager *pPager;                 /* The pager this page is part of */
+  Pgno pgno;                     /* Page number for this page */
+#ifdef SQLITE_CHECK_PAGES
+  u32 pageHash;                  /* Hash of page content */
+#endif
+  u16 flags;                     /* PGHDR flags defined below */
+
+  /**********************************************************************
+  ** Elements above are public.  All that follows is private to pcache.c
+  ** and should not be accessed by other modules.
+  */
+  i16 nRef;                      /* Number of users of this page */
+  PCache *pCache;                /* Cache that owns this page */
+
+  PgHdr *pDirtyNext;             /* Next element in list of dirty pages */
+  PgHdr *pDirtyPrev;             /* Previous element in list of dirty pages */
+};
+
+/* Bit values for PgHdr.flags */
+#define PGHDR_CLEAN           0x001  /* Page not on the PCache.pDirty list */
+#define PGHDR_DIRTY           0x002  /* Page is on the PCache.pDirty list */
+#define PGHDR_WRITEABLE       0x004  /* Journaled and ready to modify */
+#define PGHDR_NEED_SYNC       0x008  /* Fsync the rollback journal before
+                                     ** writing this page to the database */
+#define PGHDR_DONT_WRITE      0x010  /* Do not write content to disk */
+#define PGHDR_MMAP            0x020  /* This is an mmap page object */
+
+#define PGHDR_WAL_APPEND      0x040  /* Appended to wal file */
+
+/* Initialize and shutdown the page cache subsystem */
+SQLITE_PRIVATE int sqlite3PcacheInitialize(void);
+SQLITE_PRIVATE void sqlite3PcacheShutdown(void);
+
+/* Page cache buffer management:
+** These routines implement SQLITE_CONFIG_PAGECACHE.
+*/
+SQLITE_PRIVATE void sqlite3PCacheBufferSetup(void *, int sz, int n);
+
+/* Create a new pager cache.
+** Under memory stress, invoke xStress to try to make pages clean.
+** Only clean and unpinned pages can be reclaimed.
+*/
+SQLITE_PRIVATE int sqlite3PcacheOpen(
+  int szPage,                    /* Size of every page */
+  int szExtra,                   /* Extra space associated with each page */
+  int bPurgeable,                /* True if pages are on backing store */
+  int (*xStress)(void*, PgHdr*), /* Call to try to make pages clean */
+  void *pStress,                 /* Argument to xStress */
+  PCache *pToInit                /* Preallocated space for the PCache */
+);
+
+/* Modify the page-size after the cache has been created. */
+SQLITE_PRIVATE int sqlite3PcacheSetPageSize(PCache *, int);
+
+/* Return the size in bytes of a PCache object.  Used to preallocate
+** storage space.
+*/
+SQLITE_PRIVATE int sqlite3PcacheSize(void);
+
+/* One release per successful fetch.  Page is pinned until released.
+** Reference counted. 
+*/
+SQLITE_PRIVATE sqlite3_pcache_page *sqlite3PcacheFetch(PCache*, Pgno, int createFlag);
+SQLITE_PRIVATE int sqlite3PcacheFetchStress(PCache*, Pgno, sqlite3_pcache_page**);
+SQLITE_PRIVATE PgHdr *sqlite3PcacheFetchFinish(PCache*, Pgno, sqlite3_pcache_page *pPage);
+SQLITE_PRIVATE void sqlite3PcacheRelease(PgHdr*);
+
+SQLITE_PRIVATE void sqlite3PcacheDrop(PgHdr*);         /* Remove page from cache */
+SQLITE_PRIVATE void sqlite3PcacheMakeDirty(PgHdr*);    /* Make sure page is marked dirty */
+SQLITE_PRIVATE void sqlite3PcacheMakeClean(PgHdr*);    /* Mark a single page as clean */
+SQLITE_PRIVATE void sqlite3PcacheCleanAll(PCache*);    /* Mark all dirty list pages as clean */
+SQLITE_PRIVATE void sqlite3PcacheClearWritable(PCache*);
+
+/* Change a page number.  Used by incr-vacuum. */
+SQLITE_PRIVATE void sqlite3PcacheMove(PgHdr*, Pgno);
+
+/* Remove all pages with pgno>x.  Reset the cache if x==0 */
+SQLITE_PRIVATE void sqlite3PcacheTruncate(PCache*, Pgno x);
+
+/* Get a list of all dirty pages in the cache, sorted by page number */
+SQLITE_PRIVATE PgHdr *sqlite3PcacheDirtyList(PCache*);
+
+/* Reset and close the cache object */
+SQLITE_PRIVATE void sqlite3PcacheClose(PCache*);
+
+/* Clear flags from pages of the page cache */
+SQLITE_PRIVATE void sqlite3PcacheClearSyncFlags(PCache *);
+
+/* Discard the contents of the cache */
+SQLITE_PRIVATE void sqlite3PcacheClear(PCache*);
+
+/* Return the total number of outstanding page references */
+SQLITE_PRIVATE int sqlite3PcacheRefCount(PCache*);
+
+/* Increment the reference count of an existing page */
+SQLITE_PRIVATE void sqlite3PcacheRef(PgHdr*);
+
+SQLITE_PRIVATE int sqlite3PcachePageRefcount(PgHdr*);
+
+/* Return the total number of pages stored in the cache */
+SQLITE_PRIVATE int sqlite3PcachePagecount(PCache*);
+
+#if defined(SQLITE_CHECK_PAGES) || defined(SQLITE_DEBUG)
+/* Iterate through all dirty pages currently stored in the cache. This
+** interface is only available if SQLITE_CHECK_PAGES is defined when the 
+** library is built.
+*/
+SQLITE_PRIVATE void sqlite3PcacheIterateDirty(PCache *pCache, void (*xIter)(PgHdr *));
+#endif
+
+#if defined(SQLITE_DEBUG)
+/* Check invariants on a PgHdr object */
+SQLITE_PRIVATE int sqlite3PcachePageSanity(PgHdr*);
+#endif
+
+/* Set and get the suggested cache-size for the specified pager-cache.
+**
+** If no global maximum is configured, then the system attempts to limit
+** the total number of pages cached by purgeable pager-caches to the sum
+** of the suggested cache-sizes.
+*/
+SQLITE_PRIVATE void sqlite3PcacheSetCachesize(PCache *, int);
+#ifdef SQLITE_TEST
+SQLITE_PRIVATE int sqlite3PcacheGetCachesize(PCache *);
+#endif
+
+/* Set or get the suggested spill-size for the specified pager-cache.
+**
+** The spill-size is the minimum number of pages in cache before the cache
+** will attempt to spill dirty pages by calling xStress.
+*/
+SQLITE_PRIVATE int sqlite3PcacheSetSpillsize(PCache *, int);
+
+/* Free up as much memory as possible from the page cache */
+SQLITE_PRIVATE void sqlite3PcacheShrink(PCache*);
+
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+/* Try to return memory used by the pcache module to the main memory heap */
+SQLITE_PRIVATE int sqlite3PcacheReleaseMemory(int);
+#endif
+
+#ifdef SQLITE_TEST
+SQLITE_PRIVATE void sqlite3PcacheStats(int*,int*,int*,int*);
+#endif
+
+SQLITE_PRIVATE void sqlite3PCacheSetDefault(void);
+
+/* Return the header size */
+SQLITE_PRIVATE int sqlite3HeaderSizePcache(void);
+SQLITE_PRIVATE int sqlite3HeaderSizePcache1(void);
+
+/* Number of dirty pages as a percentage of the configured cache size */
+SQLITE_PRIVATE int sqlite3PCachePercentDirty(PCache*);
+
+#endif /* _PCACHE_H_ */
+
+/************** End of pcache.h **********************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+/************** Include os.h in the middle of sqliteInt.h ********************/
+/************** Begin file os.h **********************************************/
+/*
+** 2001 September 16
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This header file (together with is companion C source-code file
+** "os.c") attempt to abstract the underlying operating system so that
+** the SQLite library will work on both POSIX and windows systems.
+**
+** This header file is #include-ed by sqliteInt.h and thus ends up
+** being included by every source file.
+*/
+#ifndef _SQLITE_OS_H_
+#define _SQLITE_OS_H_
+
+/*
+** Attempt to automatically detect the operating system and setup the
+** necessary pre-processor macros for it.
+*/
+/************** Include os_setup.h in the middle of os.h *********************/
+/************** Begin file os_setup.h ****************************************/
+/*
+** 2013 November 25
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains pre-processor directives related to operating system
+** detection and/or setup.
+*/
+#ifndef SQLITE_OS_SETUP_H
+#define SQLITE_OS_SETUP_H
+
+/*
+** Figure out if we are dealing with Unix, Windows, or some other operating
+** system.
+**
+** After the following block of preprocess macros, all of SQLITE_OS_UNIX,
+** SQLITE_OS_WIN, and SQLITE_OS_OTHER will defined to either 1 or 0.  One of
+** the three will be 1.  The other two will be 0.
+*/
+#if defined(SQLITE_OS_OTHER)
+#  if SQLITE_OS_OTHER==1
+#    undef SQLITE_OS_UNIX
+#    define SQLITE_OS_UNIX 0
+#    undef SQLITE_OS_WIN
+#    define SQLITE_OS_WIN 0
+#  else
+#    undef SQLITE_OS_OTHER
+#  endif
+#endif
+#if !defined(SQLITE_OS_UNIX) && !defined(SQLITE_OS_OTHER)
+#  define SQLITE_OS_OTHER 0
+#  ifndef SQLITE_OS_WIN
+#    if defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) || \
+        defined(__MINGW32__) || defined(__BORLANDC__)
+#      define SQLITE_OS_WIN 1
+#      define SQLITE_OS_UNIX 0
+#    else
+#      define SQLITE_OS_WIN 0
+#      define SQLITE_OS_UNIX 1
+#    endif
+#  else
+#    define SQLITE_OS_UNIX 0
+#  endif
+#else
+#  ifndef SQLITE_OS_WIN
+#    define SQLITE_OS_WIN 0
+#  endif
+#endif
+
+#endif /* SQLITE_OS_SETUP_H */
+
+/************** End of os_setup.h ********************************************/
+/************** Continuing where we left off in os.h *************************/
+
+/* If the SET_FULLSYNC macro is not defined above, then make it
+** a no-op
+*/
+#ifndef SET_FULLSYNC
+# define SET_FULLSYNC(x,y)
+#endif
+
+/*
+** The default size of a disk sector
+*/
+#ifndef SQLITE_DEFAULT_SECTOR_SIZE
+# define SQLITE_DEFAULT_SECTOR_SIZE 4096
+#endif
+
+/*
+** Temporary files are named starting with this prefix followed by 16 random
+** alphanumeric characters, and no file extension. They are stored in the
+** OS's standard temporary file directory, and are deleted prior to exit.
+** If sqlite is being embedded in another program, you may wish to change the
+** prefix to reflect your program's name, so that if your program exits
+** prematurely, old temporary files can be easily identified. This can be done
+** using -DSQLITE_TEMP_FILE_PREFIX=myprefix_ on the compiler command line.
+**
+** 2006-10-31:  The default prefix used to be "sqlite_".  But then
+** Mcafee started using SQLite in their anti-virus product and it
+** started putting files with the "sqlite" name in the c:/temp folder.
+** This annoyed many windows users.  Those users would then do a 
+** Google search for "sqlite", find the telephone numbers of the
+** developers and call to wake them up at night and complain.
+** For this reason, the default name prefix is changed to be "sqlite" 
+** spelled backwards.  So the temp files are still identified, but
+** anybody smart enough to figure out the code is also likely smart
+** enough to know that calling the developer will not help get rid
+** of the file.
+*/
+#ifndef SQLITE_TEMP_FILE_PREFIX
+# define SQLITE_TEMP_FILE_PREFIX "etilqs_"
+#endif
+
+/*
+** The following values may be passed as the second argument to
+** sqlite3OsLock(). The various locks exhibit the following semantics:
+**
+** SHARED:    Any number of processes may hold a SHARED lock simultaneously.
+** RESERVED:  A single process may hold a RESERVED lock on a file at
+**            any time. Other processes may hold and obtain new SHARED locks.
+** PENDING:   A single process may hold a PENDING lock on a file at
+**            any one time. Existing SHARED locks may persist, but no new
+**            SHARED locks may be obtained by other processes.
+** EXCLUSIVE: An EXCLUSIVE lock precludes all other locks.
+**
+** PENDING_LOCK may not be passed directly to sqlite3OsLock(). Instead, a
+** process that requests an EXCLUSIVE lock may actually obtain a PENDING
+** lock. This can be upgraded to an EXCLUSIVE lock by a subsequent call to
+** sqlite3OsLock().
+*/
+#define NO_LOCK         0
+#define SHARED_LOCK     1
+#define RESERVED_LOCK   2
+#define PENDING_LOCK    3
+#define EXCLUSIVE_LOCK  4
+
+/*
+** File Locking Notes:  (Mostly about windows but also some info for Unix)
+**
+** We cannot use LockFileEx() or UnlockFileEx() on Win95/98/ME because
+** those functions are not available.  So we use only LockFile() and
+** UnlockFile().
+**
+** LockFile() prevents not just writing but also reading by other processes.
+** A SHARED_LOCK is obtained by locking a single randomly-chosen 
+** byte out of a specific range of bytes. The lock byte is obtained at 
+** random so two separate readers can probably access the file at the 
+** same time, unless they are unlucky and choose the same lock byte.
+** An EXCLUSIVE_LOCK is obtained by locking all bytes in the range.
+** There can only be one writer.  A RESERVED_LOCK is obtained by locking
+** a single byte of the file that is designated as the reserved lock byte.
+** A PENDING_LOCK is obtained by locking a designated byte different from
+** the RESERVED_LOCK byte.
+**
+** On WinNT/2K/XP systems, LockFileEx() and UnlockFileEx() are available,
+** which means we can use reader/writer locks.  When reader/writer locks
+** are used, the lock is placed on the same range of bytes that is used
+** for probabilistic locking in Win95/98/ME.  Hence, the locking scheme
+** will support two or more Win95 readers or two or more WinNT readers.
+** But a single Win95 reader will lock out all WinNT readers and a single
+** WinNT reader will lock out all other Win95 readers.
+**
+** The following #defines specify the range of bytes used for locking.
+** SHARED_SIZE is the number of bytes available in the pool from which
+** a random byte is selected for a shared lock.  The pool of bytes for
+** shared locks begins at SHARED_FIRST. 
+**
+** The same locking strategy and
+** byte ranges are used for Unix.  This leaves open the possibility of having
+** clients on win95, winNT, and unix all talking to the same shared file
+** and all locking correctly.  To do so would require that samba (or whatever
+** tool is being used for file sharing) implements locks correctly between
+** windows and unix.  I'm guessing that isn't likely to happen, but by
+** using the same locking range we are at least open to the possibility.
+**
+** Locking in windows is manditory.  For this reason, we cannot store
+** actual data in the bytes used for locking.  The pager never allocates
+** the pages involved in locking therefore.  SHARED_SIZE is selected so
+** that all locks will fit on a single page even at the minimum page size.
+** PENDING_BYTE defines the beginning of the locks.  By default PENDING_BYTE
+** is set high so that we don't have to allocate an unused page except
+** for very large databases.  But one should test the page skipping logic 
+** by setting PENDING_BYTE low and running the entire regression suite.
+**
+** Changing the value of PENDING_BYTE results in a subtly incompatible
+** file format.  Depending on how it is changed, you might not notice
+** the incompatibility right away, even running a full regression test.
+** The default location of PENDING_BYTE is the first byte past the
+** 1GB boundary.
+**
+*/
+#ifdef SQLITE_OMIT_WSD
+# define PENDING_BYTE     (0x40000000)
+#else
+# define PENDING_BYTE      sqlite3PendingByte
+#endif
+#define RESERVED_BYTE     (PENDING_BYTE+1)
+#define SHARED_FIRST      (PENDING_BYTE+2)
+#define SHARED_SIZE       510
+
+/*
+** Wrapper around OS specific sqlite3_os_init() function.
+*/
+SQLITE_PRIVATE int sqlite3OsInit(void);
+
+/* 
+** Functions for accessing sqlite3_file methods 
+*/
+SQLITE_PRIVATE void sqlite3OsClose(sqlite3_file*);
+SQLITE_PRIVATE int sqlite3OsRead(sqlite3_file*, void*, int amt, i64 offset);
+SQLITE_PRIVATE int sqlite3OsWrite(sqlite3_file*, const void*, int amt, i64 offset);
+SQLITE_PRIVATE int sqlite3OsTruncate(sqlite3_file*, i64 size);
+SQLITE_PRIVATE int sqlite3OsSync(sqlite3_file*, int);
+SQLITE_PRIVATE int sqlite3OsFileSize(sqlite3_file*, i64 *pSize);
+SQLITE_PRIVATE int sqlite3OsLock(sqlite3_file*, int);
+SQLITE_PRIVATE int sqlite3OsUnlock(sqlite3_file*, int);
+SQLITE_PRIVATE int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut);
+SQLITE_PRIVATE int sqlite3OsFileControl(sqlite3_file*,int,void*);
+SQLITE_PRIVATE void sqlite3OsFileControlHint(sqlite3_file*,int,void*);
+#define SQLITE_FCNTL_DB_UNCHANGED 0xca093fa0
+SQLITE_PRIVATE int sqlite3OsSectorSize(sqlite3_file *id);
+SQLITE_PRIVATE int sqlite3OsDeviceCharacteristics(sqlite3_file *id);
+SQLITE_PRIVATE int sqlite3OsShmMap(sqlite3_file *,int,int,int,void volatile **);
+SQLITE_PRIVATE int sqlite3OsShmLock(sqlite3_file *id, int, int, int);
+SQLITE_PRIVATE void sqlite3OsShmBarrier(sqlite3_file *id);
+SQLITE_PRIVATE int sqlite3OsShmUnmap(sqlite3_file *id, int);
+SQLITE_PRIVATE int sqlite3OsFetch(sqlite3_file *id, i64, int, void **);
+SQLITE_PRIVATE int sqlite3OsUnfetch(sqlite3_file *, i64, void *);
+
+
+/* 
+** Functions for accessing sqlite3_vfs methods 
+*/
+SQLITE_PRIVATE int sqlite3OsOpen(sqlite3_vfs *, const char *, sqlite3_file*, int, int *);
+SQLITE_PRIVATE int sqlite3OsDelete(sqlite3_vfs *, const char *, int);
+SQLITE_PRIVATE int sqlite3OsAccess(sqlite3_vfs *, const char *, int, int *pResOut);
+SQLITE_PRIVATE int sqlite3OsFullPathname(sqlite3_vfs *, const char *, int, char *);
+#ifndef SQLITE_OMIT_LOAD_EXTENSION
+SQLITE_PRIVATE void *sqlite3OsDlOpen(sqlite3_vfs *, const char *);
+SQLITE_PRIVATE void sqlite3OsDlError(sqlite3_vfs *, int, char *);
+SQLITE_PRIVATE void (*sqlite3OsDlSym(sqlite3_vfs *, void *, const char *))(void);
+SQLITE_PRIVATE void sqlite3OsDlClose(sqlite3_vfs *, void *);
+#endif /* SQLITE_OMIT_LOAD_EXTENSION */
+SQLITE_PRIVATE int sqlite3OsRandomness(sqlite3_vfs *, int, char *);
+SQLITE_PRIVATE int sqlite3OsSleep(sqlite3_vfs *, int);
+SQLITE_PRIVATE int sqlite3OsGetLastError(sqlite3_vfs*);
+SQLITE_PRIVATE int sqlite3OsCurrentTimeInt64(sqlite3_vfs *, sqlite3_int64*);
+
+/*
+** Convenience functions for opening and closing files using 
+** sqlite3_malloc() to obtain space for the file-handle structure.
+*/
+SQLITE_PRIVATE int sqlite3OsOpenMalloc(sqlite3_vfs *, const char *, sqlite3_file **, int,int*);
+SQLITE_PRIVATE void sqlite3OsCloseFree(sqlite3_file *);
+
+#endif /* _SQLITE_OS_H_ */
+
+/************** End of os.h **************************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+/************** Include mutex.h in the middle of sqliteInt.h *****************/
+/************** Begin file mutex.h *******************************************/
+/*
+** 2007 August 28
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains the common header for all mutex implementations.
+** The sqliteInt.h header #includes this file so that it is available
+** to all source files.  We break it out in an effort to keep the code
+** better organized.
+**
+** NOTE:  source files should *not* #include this header file directly.
+** Source files should #include the sqliteInt.h file and let that file
+** include this one indirectly.
+*/
+
+
+/*
+** Figure out what version of the code to use.  The choices are
+**
+**   SQLITE_MUTEX_OMIT         No mutex logic.  Not even stubs.  The
+**                             mutexes implementation cannot be overridden
+**                             at start-time.
+**
+**   SQLITE_MUTEX_NOOP         For single-threaded applications.  No
+**                             mutual exclusion is provided.  But this
+**                             implementation can be overridden at
+**                             start-time.
+**
+**   SQLITE_MUTEX_PTHREADS     For multi-threaded applications on Unix.
+**
+**   SQLITE_MUTEX_W32          For multi-threaded applications on Win32.
+*/
+#if !SQLITE_THREADSAFE
+# define SQLITE_MUTEX_OMIT
+#endif
+#if SQLITE_THREADSAFE && !defined(SQLITE_MUTEX_NOOP)
+#  if SQLITE_OS_UNIX
+#    define SQLITE_MUTEX_PTHREADS
+#  elif SQLITE_OS_WIN
+#    define SQLITE_MUTEX_W32
+#  else
+#    define SQLITE_MUTEX_NOOP
+#  endif
+#endif
+
+#ifdef SQLITE_MUTEX_OMIT
+/*
+** If this is a no-op implementation, implement everything as macros.
+*/
+#define sqlite3_mutex_alloc(X)    ((sqlite3_mutex*)8)
+#define sqlite3_mutex_free(X)
+#define sqlite3_mutex_enter(X)    
+#define sqlite3_mutex_try(X)      SQLITE_OK
+#define sqlite3_mutex_leave(X)    
+#define sqlite3_mutex_held(X)     ((void)(X),1)
+#define sqlite3_mutex_notheld(X)  ((void)(X),1)
+#define sqlite3MutexAlloc(X)      ((sqlite3_mutex*)8)
+#define sqlite3MutexInit()        SQLITE_OK
+#define sqlite3MutexEnd()
+#define MUTEX_LOGIC(X)
+#else
+#define MUTEX_LOGIC(X)            X
+#endif /* defined(SQLITE_MUTEX_OMIT) */
+
+/************** End of mutex.h ***********************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+
+/* The SQLITE_EXTRA_DURABLE compile-time option used to set the default
+** synchronous setting to EXTRA.  It is no longer supported.
+*/
+#ifdef SQLITE_EXTRA_DURABLE
+# warning Use SQLITE_DEFAULT_SYNCHRONOUS=3 instead of SQLITE_EXTRA_DURABLE
+# define SQLITE_DEFAULT_SYNCHRONOUS 3
+#endif
+
+/*
+** Default synchronous levels.
+**
+** Note that (for historcal reasons) the PAGER_SYNCHRONOUS_* macros differ
+** from the SQLITE_DEFAULT_SYNCHRONOUS value by 1.
+**
+**           PAGER_SYNCHRONOUS       DEFAULT_SYNCHRONOUS
+**   OFF           1                         0
+**   NORMAL        2                         1
+**   FULL          3                         2
+**   EXTRA         4                         3
+**
+** The "PRAGMA synchronous" statement also uses the zero-based numbers.
+** In other words, the zero-based numbers are used for all external interfaces
+** and the one-based values are used internally.
+*/
+#ifndef SQLITE_DEFAULT_SYNCHRONOUS
+# define SQLITE_DEFAULT_SYNCHRONOUS (PAGER_SYNCHRONOUS_FULL-1)
+#endif
+#ifndef SQLITE_DEFAULT_WAL_SYNCHRONOUS
+# define SQLITE_DEFAULT_WAL_SYNCHRONOUS SQLITE_DEFAULT_SYNCHRONOUS
+#endif
+
+/*
+** Each database file to be accessed by the system is an instance
+** of the following structure.  There are normally two of these structures
+** in the sqlite.aDb[] array.  aDb[0] is the main database file and
+** aDb[1] is the database file used to hold temporary tables.  Additional
+** databases may be attached.
+*/
+struct Db {
+  char *zDbSName;      /* Name of this database. (schema name, not filename) */
+  Btree *pBt;          /* The B*Tree structure for this database file */
+  u8 safety_level;     /* How aggressive at syncing data to disk */
+  u8 bSyncSet;         /* True if "PRAGMA synchronous=N" has been run */
+  Schema *pSchema;     /* Pointer to database schema (possibly shared) */
+};
+
+/*
+** An instance of the following structure stores a database schema.
+**
+** Most Schema objects are associated with a Btree.  The exception is
+** the Schema for the TEMP databaes (sqlite3.aDb[1]) which is free-standing.
+** In shared cache mode, a single Schema object can be shared by multiple
+** Btrees that refer to the same underlying BtShared object.
+**
+** Schema objects are automatically deallocated when the last Btree that
+** references them is destroyed.   The TEMP Schema is manually freed by
+** sqlite3_close().
+*
+** A thread must be holding a mutex on the corresponding Btree in order
+** to access Schema content.  This implies that the thread must also be
+** holding a mutex on the sqlite3 connection pointer that owns the Btree.
+** For a TEMP Schema, only the connection mutex is required.
+*/
+struct Schema {
+  int schema_cookie;   /* Database schema version number for this file */
+  int iGeneration;     /* Generation counter.  Incremented with each change */
+  Hash tblHash;        /* All tables indexed by name */
+  Hash idxHash;        /* All (named) indices indexed by name */
+  Hash trigHash;       /* All triggers indexed by name */
+  Hash fkeyHash;       /* All foreign keys by referenced table name */
+  Table *pSeqTab;      /* The sqlite_sequence table used by AUTOINCREMENT */
+  u8 file_format;      /* Schema format version for this file */
+  u8 enc;              /* Text encoding used by this database */
+  u16 schemaFlags;     /* Flags associated with this schema */
+  int cache_size;      /* Number of pages to use in the cache */
+};
+
+/*
+** These macros can be used to test, set, or clear bits in the
+** Db.pSchema->flags field.
+*/
+#define DbHasProperty(D,I,P)     (((D)->aDb[I].pSchema->schemaFlags&(P))==(P))
+#define DbHasAnyProperty(D,I,P)  (((D)->aDb[I].pSchema->schemaFlags&(P))!=0)
+#define DbSetProperty(D,I,P)     (D)->aDb[I].pSchema->schemaFlags|=(P)
+#define DbClearProperty(D,I,P)   (D)->aDb[I].pSchema->schemaFlags&=~(P)
+
+/*
+** Allowed values for the DB.pSchema->flags field.
+**
+** The DB_SchemaLoaded flag is set after the database schema has been
+** read into internal hash tables.
+**
+** DB_UnresetViews means that one or more views have column names that
+** have been filled out.  If the schema changes, these column names might
+** changes and so the view will need to be reset.
+*/
+#define DB_SchemaLoaded    0x0001  /* The schema has been loaded */
+#define DB_UnresetViews    0x0002  /* Some views have defined column names */
+#define DB_Empty           0x0004  /* The file is empty (length 0 bytes) */
+
+/*
+** The number of different kinds of things that can be limited
+** using the sqlite3_limit() interface.
+*/
+#define SQLITE_N_LIMIT (SQLITE_LIMIT_WORKER_THREADS+1)
+
+/*
+** Lookaside malloc is a set of fixed-size buffers that can be used
+** to satisfy small transient memory allocation requests for objects
+** associated with a particular database connection.  The use of
+** lookaside malloc provides a significant performance enhancement
+** (approx 10%) by avoiding numerous malloc/free requests while parsing
+** SQL statements.
+**
+** The Lookaside structure holds configuration information about the
+** lookaside malloc subsystem.  Each available memory allocation in
+** the lookaside subsystem is stored on a linked list of LookasideSlot
+** objects.
+**
+** Lookaside allocations are only allowed for objects that are associated
+** with a particular database connection.  Hence, schema information cannot
+** be stored in lookaside because in shared cache mode the schema information
+** is shared by multiple database connections.  Therefore, while parsing
+** schema information, the Lookaside.bEnabled flag is cleared so that
+** lookaside allocations are not used to construct the schema objects.
+*/
+struct Lookaside {
+  u32 bDisable;           /* Only operate the lookaside when zero */
+  u16 sz;                 /* Size of each buffer in bytes */
+  u8 bMalloced;           /* True if pStart obtained from sqlite3_malloc() */
+  int nOut;               /* Number of buffers currently checked out */
+  int mxOut;              /* Highwater mark for nOut */
+  int anStat[3];          /* 0: hits.  1: size misses.  2: full misses */
+  LookasideSlot *pFree;   /* List of available buffers */
+  void *pStart;           /* First byte of available memory space */
+  void *pEnd;             /* First byte past end of available space */
+};
+struct LookasideSlot {
+  LookasideSlot *pNext;    /* Next buffer in the list of free buffers */
+};
+
+/*
+** A hash table for built-in function definitions.  (Application-defined
+** functions use a regular table table from hash.h.)
+**
+** Hash each FuncDef structure into one of the FuncDefHash.a[] slots.
+** Collisions are on the FuncDef.u.pHash chain.
+*/
+#define SQLITE_FUNC_HASH_SZ 23
+struct FuncDefHash {
+  FuncDef *a[SQLITE_FUNC_HASH_SZ];       /* Hash table for functions */
+};
+
+#ifdef SQLITE_USER_AUTHENTICATION
+/*
+** Information held in the "sqlite3" database connection object and used
+** to manage user authentication.
+*/
+typedef struct sqlite3_userauth sqlite3_userauth;
+struct sqlite3_userauth {
+  u8 authLevel;                 /* Current authentication level */
+  int nAuthPW;                  /* Size of the zAuthPW in bytes */
+  char *zAuthPW;                /* Password used to authenticate */
+  char *zAuthUser;              /* User name used to authenticate */
+};
+
+/* Allowed values for sqlite3_userauth.authLevel */
+#define UAUTH_Unknown     0     /* Authentication not yet checked */
+#define UAUTH_Fail        1     /* User authentication failed */
+#define UAUTH_User        2     /* Authenticated as a normal user */
+#define UAUTH_Admin       3     /* Authenticated as an administrator */
+
+/* Functions used only by user authorization logic */
+SQLITE_PRIVATE int sqlite3UserAuthTable(const char*);
+SQLITE_PRIVATE int sqlite3UserAuthCheckLogin(sqlite3*,const char*,u8*);
+SQLITE_PRIVATE void sqlite3UserAuthInit(sqlite3*);
+SQLITE_PRIVATE void sqlite3CryptFunc(sqlite3_context*,int,sqlite3_value**);
+
+#endif /* SQLITE_USER_AUTHENTICATION */
+
+/*
+** typedef for the authorization callback function.
+*/
+#ifdef SQLITE_USER_AUTHENTICATION
+  typedef int (*sqlite3_xauth)(void*,int,const char*,const char*,const char*,
+                               const char*, const char*);
+#else
+  typedef int (*sqlite3_xauth)(void*,int,const char*,const char*,const char*,
+                               const char*);
+#endif
+
+#ifndef SQLITE_OMIT_DEPRECATED
+/* This is an extra SQLITE_TRACE macro that indicates "legacy" tracing
+** in the style of sqlite3_trace()
+*/
+#define SQLITE_TRACE_LEGACY  0x80
+#else
+#define SQLITE_TRACE_LEGACY  0
+#endif /* SQLITE_OMIT_DEPRECATED */
+
+
+/*
+** Each database connection is an instance of the following structure.
+*/
+struct sqlite3 {
+  sqlite3_vfs *pVfs;            /* OS Interface */
+  struct Vdbe *pVdbe;           /* List of active virtual machines */
+  CollSeq *pDfltColl;           /* The default collating sequence (BINARY) */
+  sqlite3_mutex *mutex;         /* Connection mutex */
+  Db *aDb;                      /* All backends */
+  int nDb;                      /* Number of backends currently in use */
+  int flags;                    /* Miscellaneous flags. See below */
+  i64 lastRowid;                /* ROWID of most recent insert (see above) */
+  i64 szMmap;                   /* Default mmap_size setting */
+  unsigned int openFlags;       /* Flags passed to sqlite3_vfs.xOpen() */
+  int errCode;                  /* Most recent error code (SQLITE_*) */
+  int errMask;                  /* & result codes with this before returning */
+  int iSysErrno;                /* Errno value from last system error */
+  u16 dbOptFlags;               /* Flags to enable/disable optimizations */
+  u8 enc;                       /* Text encoding */
+  u8 autoCommit;                /* The auto-commit flag. */
+  u8 temp_store;                /* 1: file 2: memory 0: default */
+  u8 mallocFailed;              /* True if we have seen a malloc failure */
+  u8 bBenignMalloc;             /* Do not require OOMs if true */
+  u8 dfltLockMode;              /* Default locking-mode for attached dbs */
+  signed char nextAutovac;      /* Autovac setting after VACUUM if >=0 */
+  u8 suppressErr;               /* Do not issue error messages if true */
+  u8 vtabOnConflict;            /* Value to return for s3_vtab_on_conflict() */
+  u8 isTransactionSavepoint;    /* True if the outermost savepoint is a TS */
+  u8 mTrace;                    /* zero or more SQLITE_TRACE flags */
+  int nextPagesize;             /* Pagesize after VACUUM if >0 */
+  u32 magic;                    /* Magic number for detect library misuse */
+  int nChange;                  /* Value returned by sqlite3_changes() */
+  int nTotalChange;             /* Value returned by sqlite3_total_changes() */
+  int aLimit[SQLITE_N_LIMIT];   /* Limits */
+  int nMaxSorterMmap;           /* Maximum size of regions mapped by sorter */
+  struct sqlite3InitInfo {      /* Information used during initialization */
+    int newTnum;                /* Rootpage of table being initialized */
+    u8 iDb;                     /* Which db file is being initialized */
+    u8 busy;                    /* TRUE if currently initializing */
+    u8 orphanTrigger;           /* Last statement is orphaned TEMP trigger */
+    u8 imposterTable;           /* Building an imposter table */
+  } init;
+  int nVdbeActive;              /* Number of VDBEs currently running */
+  int nVdbeRead;                /* Number of active VDBEs that read or write */
+  int nVdbeWrite;               /* Number of active VDBEs that read and write */
+  int nVdbeExec;                /* Number of nested calls to VdbeExec() */
+  int nVDestroy;                /* Number of active OP_VDestroy operations */
+  int nExtension;               /* Number of loaded extensions */
+  void **aExtension;            /* Array of shared library handles */
+  int (*xTrace)(u32,void*,void*,void*);     /* Trace function */
+  void *pTraceArg;                          /* Argument to the trace function */
+  void (*xProfile)(void*,const char*,u64);  /* Profiling function */
+  void *pProfileArg;                        /* Argument to profile function */
+  void *pCommitArg;                 /* Argument to xCommitCallback() */
+  int (*xCommitCallback)(void*);    /* Invoked at every commit. */
+  void *pRollbackArg;               /* Argument to xRollbackCallback() */
+  void (*xRollbackCallback)(void*); /* Invoked at every commit. */
+  void *pUpdateArg;
+  void (*xUpdateCallback)(void*,int, const char*,const char*,sqlite_int64);
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+  void *pPreUpdateArg;          /* First argument to xPreUpdateCallback */
+  void (*xPreUpdateCallback)(   /* Registered using sqlite3_preupdate_hook() */
+    void*,sqlite3*,int,char const*,char const*,sqlite3_int64,sqlite3_int64
+  );
+  PreUpdate *pPreUpdate;        /* Context for active pre-update callback */
+#endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
+#ifndef SQLITE_OMIT_WAL
+  int (*xWalCallback)(void *, sqlite3 *, const char *, int);
+  void *pWalArg;
+#endif
+  void(*xCollNeeded)(void*,sqlite3*,int eTextRep,const char*);
+  void(*xCollNeeded16)(void*,sqlite3*,int eTextRep,const void*);
+  void *pCollNeededArg;
+  sqlite3_value *pErr;          /* Most recent error message */
+  union {
+    volatile int isInterrupted; /* True if sqlite3_interrupt has been called */
+    double notUsed1;            /* Spacer */
+  } u1;
+  Lookaside lookaside;          /* Lookaside malloc configuration */
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  sqlite3_xauth xAuth;          /* Access authorization function */
+  void *pAuthArg;               /* 1st argument to the access auth function */
+#endif
+#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
+  int (*xProgress)(void *);     /* The progress callback */
+  void *pProgressArg;           /* Argument to the progress callback */
+  unsigned nProgressOps;        /* Number of opcodes for progress callback */
+#endif
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  int nVTrans;                  /* Allocated size of aVTrans */
+  Hash aModule;                 /* populated by sqlite3_create_module() */
+  VtabCtx *pVtabCtx;            /* Context for active vtab connect/create */
+  VTable **aVTrans;             /* Virtual tables with open transactions */
+  VTable *pDisconnect;    /* Disconnect these in next sqlite3_prepare() */
+#endif
+  Hash aFunc;                   /* Hash table of connection functions */
+  Hash aCollSeq;                /* All collating sequences */
+  BusyHandler busyHandler;      /* Busy callback */
+  Db aDbStatic[2];              /* Static space for the 2 default backends */
+  Savepoint *pSavepoint;        /* List of active savepoints */
+  int busyTimeout;              /* Busy handler timeout, in msec */
+  int nSavepoint;               /* Number of non-transaction savepoints */
+  int nStatement;               /* Number of nested statement-transactions  */
+  i64 nDeferredCons;            /* Net deferred constraints this transaction. */
+  i64 nDeferredImmCons;         /* Net deferred immediate constraints */
+  int *pnBytesFreed;            /* If not NULL, increment this in DbFree() */
+#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
+  /* The following variables are all protected by the STATIC_MASTER
+  ** mutex, not by sqlite3.mutex. They are used by code in notify.c.
+  **
+  ** When X.pUnlockConnection==Y, that means that X is waiting for Y to
+  ** unlock so that it can proceed.
+  **
+  ** When X.pBlockingConnection==Y, that means that something that X tried
+  ** tried to do recently failed with an SQLITE_LOCKED error due to locks
+  ** held by Y.
+  */
+  sqlite3 *pBlockingConnection; /* Connection that caused SQLITE_LOCKED */
+  sqlite3 *pUnlockConnection;           /* Connection to watch for unlock */
+  void *pUnlockArg;                     /* Argument to xUnlockNotify */
+  void (*xUnlockNotify)(void **, int);  /* Unlock notify callback */
+  sqlite3 *pNextBlocked;        /* Next in list of all blocked connections */
+#endif
+#ifdef SQLITE_USER_AUTHENTICATION
+  sqlite3_userauth auth;        /* User authentication information */
+#endif
+};
+
+/*
+** A macro to discover the encoding of a database.
+*/
+#define SCHEMA_ENC(db) ((db)->aDb[0].pSchema->enc)
+#define ENC(db)        ((db)->enc)
+
+/*
+** Possible values for the sqlite3.flags.
+**
+** Value constraints (enforced via assert()):
+**      SQLITE_FullFSync     == PAGER_FULLFSYNC
+**      SQLITE_CkptFullFSync == PAGER_CKPT_FULLFSYNC
+**      SQLITE_CacheSpill    == PAGER_CACHE_SPILL
+*/
+#define SQLITE_VdbeTrace      0x00000001  /* True to trace VDBE execution */
+#define SQLITE_InternChanges  0x00000002  /* Uncommitted Hash table changes */
+#define SQLITE_FullColNames   0x00000004  /* Show full column names on SELECT */
+#define SQLITE_FullFSync      0x00000008  /* Use full fsync on the backend */
+#define SQLITE_CkptFullFSync  0x00000010  /* Use full fsync for checkpoint */
+#define SQLITE_CacheSpill     0x00000020  /* OK to spill pager cache */
+#define SQLITE_ShortColNames  0x00000040  /* Show short columns names */
+#define SQLITE_CountRows      0x00000080  /* Count rows changed by INSERT, */
+                                          /*   DELETE, or UPDATE and return */
+                                          /*   the count using a callback. */
+#define SQLITE_NullCallback   0x00000100  /* Invoke the callback once if the */
+                                          /*   result set is empty */
+#define SQLITE_SqlTrace       0x00000200  /* Debug print SQL as it executes */
+#define SQLITE_VdbeListing    0x00000400  /* Debug listings of VDBE programs */
+#define SQLITE_WriteSchema    0x00000800  /* OK to update SQLITE_MASTER */
+#define SQLITE_VdbeAddopTrace 0x00001000  /* Trace sqlite3VdbeAddOp() calls */
+#define SQLITE_IgnoreChecks   0x00002000  /* Do not enforce check constraints */
+#define SQLITE_ReadUncommitted 0x0004000  /* For shared-cache mode */
+#define SQLITE_LegacyFileFmt  0x00008000  /* Create new databases in format 1 */
+#define SQLITE_RecoveryMode   0x00010000  /* Ignore schema errors */
+#define SQLITE_ReverseOrder   0x00020000  /* Reverse unordered SELECTs */
+#define SQLITE_RecTriggers    0x00040000  /* Enable recursive triggers */
+#define SQLITE_ForeignKeys    0x00080000  /* Enforce foreign key constraints  */
+#define SQLITE_AutoIndex      0x00100000  /* Enable automatic indexes */
+#define SQLITE_PreferBuiltin  0x00200000  /* Preference to built-in funcs */
+#define SQLITE_LoadExtension  0x00400000  /* Enable load_extension */
+#define SQLITE_LoadExtFunc    0x00800000  /* Enable load_extension() SQL func */
+#define SQLITE_EnableTrigger  0x01000000  /* True to enable triggers */
+#define SQLITE_DeferFKs       0x02000000  /* Defer all FK constraints */
+#define SQLITE_QueryOnly      0x04000000  /* Disable database changes */
+#define SQLITE_VdbeEQP        0x08000000  /* Debug EXPLAIN QUERY PLAN */
+#define SQLITE_Vacuum         0x10000000  /* Currently in a VACUUM */
+#define SQLITE_CellSizeCk     0x20000000  /* Check btree cell sizes on load */
+#define SQLITE_Fts3Tokenizer  0x40000000  /* Enable fts3_tokenizer(2) */
+
+
+/*
+** Bits of the sqlite3.dbOptFlags field that are used by the
+** sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS,...) interface to
+** selectively disable various optimizations.
+*/
+#define SQLITE_QueryFlattener 0x0001   /* Query flattening */
+#define SQLITE_ColumnCache    0x0002   /* Column cache */
+#define SQLITE_GroupByOrder   0x0004   /* GROUPBY cover of ORDERBY */
+#define SQLITE_FactorOutConst 0x0008   /* Constant factoring */
+/*                not used    0x0010   // Was: SQLITE_IdxRealAsInt */
+#define SQLITE_DistinctOpt    0x0020   /* DISTINCT using indexes */
+#define SQLITE_CoverIdxScan   0x0040   /* Covering index scans */
+#define SQLITE_OrderByIdxJoin 0x0080   /* ORDER BY of joins via index */
+#define SQLITE_SubqCoroutine  0x0100   /* Evaluate subqueries as coroutines */
+#define SQLITE_Transitive     0x0200   /* Transitive constraints */
+#define SQLITE_OmitNoopJoin   0x0400   /* Omit unused tables in joins */
+#define SQLITE_Stat34         0x0800   /* Use STAT3 or STAT4 data */
+#define SQLITE_CursorHints    0x2000   /* Add OP_CursorHint opcodes */
+#define SQLITE_AllOpts        0xffff   /* All optimizations */
+
+/*
+** Macros for testing whether or not optimizations are enabled or disabled.
+*/
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+#define OptimizationDisabled(db, mask)  (((db)->dbOptFlags&(mask))!=0)
+#define OptimizationEnabled(db, mask)   (((db)->dbOptFlags&(mask))==0)
+#else
+#define OptimizationDisabled(db, mask)  0
+#define OptimizationEnabled(db, mask)   1
+#endif
+
+/*
+** Return true if it OK to factor constant expressions into the initialization
+** code. The argument is a Parse object for the code generator.
+*/
+#define ConstFactorOk(P) ((P)->okConstFactor)
+
+/*
+** Possible values for the sqlite.magic field.
+** The numbers are obtained at random and have no special meaning, other
+** than being distinct from one another.
+*/
+#define SQLITE_MAGIC_OPEN     0xa029a697  /* Database is open */
+#define SQLITE_MAGIC_CLOSED   0x9f3c2d33  /* Database is closed */
+#define SQLITE_MAGIC_SICK     0x4b771290  /* Error and awaiting close */
+#define SQLITE_MAGIC_BUSY     0xf03b7906  /* Database currently in use */
+#define SQLITE_MAGIC_ERROR    0xb5357930  /* An SQLITE_MISUSE error occurred */
+#define SQLITE_MAGIC_ZOMBIE   0x64cffc7f  /* Close with last statement close */
+
+/*
+** Each SQL function is defined by an instance of the following
+** structure.  For global built-in functions (ex: substr(), max(), count())
+** a pointer to this structure is held in the sqlite3BuiltinFunctions object.
+** For per-connection application-defined functions, a pointer to this
+** structure is held in the db->aHash hash table.
+**
+** The u.pHash field is used by the global built-ins.  The u.pDestructor
+** field is used by per-connection app-def functions.
+*/
+struct FuncDef {
+  i8 nArg;             /* Number of arguments.  -1 means unlimited */
+  u16 funcFlags;       /* Some combination of SQLITE_FUNC_* */
+  void *pUserData;     /* User data parameter */
+  FuncDef *pNext;      /* Next function with same name */
+  void (*xSFunc)(sqlite3_context*,int,sqlite3_value**); /* func or agg-step */
+  void (*xFinalize)(sqlite3_context*);                  /* Agg finalizer */
+  const char *zName;   /* SQL name of the function. */
+  union {
+    FuncDef *pHash;      /* Next with a different name but the same hash */
+    FuncDestructor *pDestructor;   /* Reference counted destructor function */
+  } u;
+};
+
+/*
+** This structure encapsulates a user-function destructor callback (as
+** configured using create_function_v2()) and a reference counter. When
+** create_function_v2() is called to create a function with a destructor,
+** a single object of this type is allocated. FuncDestructor.nRef is set to
+** the number of FuncDef objects created (either 1 or 3, depending on whether
+** or not the specified encoding is SQLITE_ANY). The FuncDef.pDestructor
+** member of each of the new FuncDef objects is set to point to the allocated
+** FuncDestructor.
+**
+** Thereafter, when one of the FuncDef objects is deleted, the reference
+** count on this object is decremented. When it reaches 0, the destructor
+** is invoked and the FuncDestructor structure freed.
+*/
+struct FuncDestructor {
+  int nRef;
+  void (*xDestroy)(void *);
+  void *pUserData;
+};
+
+/*
+** Possible values for FuncDef.flags.  Note that the _LENGTH and _TYPEOF
+** values must correspond to OPFLAG_LENGTHARG and OPFLAG_TYPEOFARG.  And
+** SQLITE_FUNC_CONSTANT must be the same as SQLITE_DETERMINISTIC.  There
+** are assert() statements in the code to verify this.
+**
+** Value constraints (enforced via assert()):
+**     SQLITE_FUNC_MINMAX    ==  NC_MinMaxAgg      == SF_MinMaxAgg
+**     SQLITE_FUNC_LENGTH    ==  OPFLAG_LENGTHARG
+**     SQLITE_FUNC_TYPEOF    ==  OPFLAG_TYPEOFARG
+**     SQLITE_FUNC_CONSTANT  ==  SQLITE_DETERMINISTIC from the API
+**     SQLITE_FUNC_ENCMASK   depends on SQLITE_UTF* macros in the API
+*/
+#define SQLITE_FUNC_ENCMASK  0x0003 /* SQLITE_UTF8, SQLITE_UTF16BE or UTF16LE */
+#define SQLITE_FUNC_LIKE     0x0004 /* Candidate for the LIKE optimization */
+#define SQLITE_FUNC_CASE     0x0008 /* Case-sensitive LIKE-type function */
+#define SQLITE_FUNC_EPHEM    0x0010 /* Ephemeral.  Delete with VDBE */
+#define SQLITE_FUNC_NEEDCOLL 0x0020 /* sqlite3GetFuncCollSeq() might be called*/
+#define SQLITE_FUNC_LENGTH   0x0040 /* Built-in length() function */
+#define SQLITE_FUNC_TYPEOF   0x0080 /* Built-in typeof() function */
+#define SQLITE_FUNC_COUNT    0x0100 /* Built-in count(*) aggregate */
+#define SQLITE_FUNC_COALESCE 0x0200 /* Built-in coalesce() or ifnull() */
+#define SQLITE_FUNC_UNLIKELY 0x0400 /* Built-in unlikely() function */
+#define SQLITE_FUNC_CONSTANT 0x0800 /* Constant inputs give a constant output */
+#define SQLITE_FUNC_MINMAX   0x1000 /* True for min() and max() aggregates */
+#define SQLITE_FUNC_SLOCHNG  0x2000 /* "Slow Change". Value constant during a
+                                    ** single query - might change over time */
+
+/*
+** The following three macros, FUNCTION(), LIKEFUNC() and AGGREGATE() are
+** used to create the initializers for the FuncDef structures.
+**
+**   FUNCTION(zName, nArg, iArg, bNC, xFunc)
+**     Used to create a scalar function definition of a function zName
+**     implemented by C function xFunc that accepts nArg arguments. The
+**     value passed as iArg is cast to a (void*) and made available
+**     as the user-data (sqlite3_user_data()) for the function. If
+**     argument bNC is true, then the SQLITE_FUNC_NEEDCOLL flag is set.
+**
+**   VFUNCTION(zName, nArg, iArg, bNC, xFunc)
+**     Like FUNCTION except it omits the SQLITE_FUNC_CONSTANT flag.
+**
+**   DFUNCTION(zName, nArg, iArg, bNC, xFunc)
+**     Like FUNCTION except it omits the SQLITE_FUNC_CONSTANT flag and
+**     adds the SQLITE_FUNC_SLOCHNG flag.  Used for date & time functions
+**     and functions like sqlite_version() that can change, but not during
+**     a single query.
+**
+**   AGGREGATE(zName, nArg, iArg, bNC, xStep, xFinal)
+**     Used to create an aggregate function definition implemented by
+**     the C functions xStep and xFinal. The first four parameters
+**     are interpreted in the same way as the first 4 parameters to
+**     FUNCTION().
+**
+**   LIKEFUNC(zName, nArg, pArg, flags)
+**     Used to create a scalar function definition of a function zName
+**     that accepts nArg arguments and is implemented by a call to C
+**     function likeFunc. Argument pArg is cast to a (void *) and made
+**     available as the function user-data (sqlite3_user_data()). The
+**     FuncDef.flags variable is set to the value passed as the flags
+**     parameter.
+*/
+#define FUNCTION(zName, nArg, iArg, bNC, xFunc) \
+  {nArg, SQLITE_FUNC_CONSTANT|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
+   SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, #zName, {0} }
+#define VFUNCTION(zName, nArg, iArg, bNC, xFunc) \
+  {nArg, SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
+   SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, #zName, {0} }
+#define DFUNCTION(zName, nArg, iArg, bNC, xFunc) \
+  {nArg, SQLITE_FUNC_SLOCHNG|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
+   SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, #zName, {0} }
+#define FUNCTION2(zName, nArg, iArg, bNC, xFunc, extraFlags) \
+  {nArg,SQLITE_FUNC_CONSTANT|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL)|extraFlags,\
+   SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, #zName, {0} }
+#define STR_FUNCTION(zName, nArg, pArg, bNC, xFunc) \
+  {nArg, SQLITE_FUNC_SLOCHNG|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
+   pArg, 0, xFunc, 0, #zName, }
+#define LIKEFUNC(zName, nArg, arg, flags) \
+  {nArg, SQLITE_FUNC_CONSTANT|SQLITE_UTF8|flags, \
+   (void *)arg, 0, likeFunc, 0, #zName, {0} }
+#define AGGREGATE(zName, nArg, arg, nc, xStep, xFinal) \
+  {nArg, SQLITE_UTF8|(nc*SQLITE_FUNC_NEEDCOLL), \
+   SQLITE_INT_TO_PTR(arg), 0, xStep,xFinal,#zName, {0}}
+#define AGGREGATE2(zName, nArg, arg, nc, xStep, xFinal, extraFlags) \
+  {nArg, SQLITE_UTF8|(nc*SQLITE_FUNC_NEEDCOLL)|extraFlags, \
+   SQLITE_INT_TO_PTR(arg), 0, xStep,xFinal,#zName, {0}}
+
+/*
+** All current savepoints are stored in a linked list starting at
+** sqlite3.pSavepoint. The first element in the list is the most recently
+** opened savepoint. Savepoints are added to the list by the vdbe
+** OP_Savepoint instruction.
+*/
+struct Savepoint {
+  char *zName;                        /* Savepoint name (nul-terminated) */
+  i64 nDeferredCons;                  /* Number of deferred fk violations */
+  i64 nDeferredImmCons;               /* Number of deferred imm fk. */
+  Savepoint *pNext;                   /* Parent savepoint (if any) */
+};
+
+/*
+** The following are used as the second parameter to sqlite3Savepoint(),
+** and as the P1 argument to the OP_Savepoint instruction.
+*/
+#define SAVEPOINT_BEGIN      0
+#define SAVEPOINT_RELEASE    1
+#define SAVEPOINT_ROLLBACK   2
+
+
+/*
+** Each SQLite module (virtual table definition) is defined by an
+** instance of the following structure, stored in the sqlite3.aModule
+** hash table.
+*/
+struct Module {
+  const sqlite3_module *pModule;       /* Callback pointers */
+  const char *zName;                   /* Name passed to create_module() */
+  void *pAux;                          /* pAux passed to create_module() */
+  void (*xDestroy)(void *);            /* Module destructor function */
+  Table *pEpoTab;                      /* Eponymous table for this module */
+};
+
+/*
+** information about each column of an SQL table is held in an instance
+** of this structure.
+*/
+struct Column {
+  char *zName;     /* Name of this column, \000, then the type */
+  Expr *pDflt;     /* Default value of this column */
+  char *zColl;     /* Collating sequence.  If NULL, use the default */
+  u8 notNull;      /* An OE_ code for handling a NOT NULL constraint */
+  char affinity;   /* One of the SQLITE_AFF_... values */
+  u8 szEst;        /* Estimated size of value in this column. sizeof(INT)==1 */
+  u8 colFlags;     /* Boolean properties.  See COLFLAG_ defines below */
+};
+
+/* Allowed values for Column.colFlags:
+*/
+#define COLFLAG_PRIMKEY  0x0001    /* Column is part of the primary key */
+#define COLFLAG_HIDDEN   0x0002    /* A hidden column in a virtual table */
+#define COLFLAG_HASTYPE  0x0004    /* Type name follows column name */
+
+/*
+** A "Collating Sequence" is defined by an instance of the following
+** structure. Conceptually, a collating sequence consists of a name and
+** a comparison routine that defines the order of that sequence.
+**
+** If CollSeq.xCmp is NULL, it means that the
+** collating sequence is undefined.  Indices built on an undefined
+** collating sequence may not be read or written.
+*/
+struct CollSeq {
+  char *zName;          /* Name of the collating sequence, UTF-8 encoded */
+  u8 enc;               /* Text encoding handled by xCmp() */
+  void *pUser;          /* First argument to xCmp() */
+  int (*xCmp)(void*,int, const void*, int, const void*);
+  void (*xDel)(void*);  /* Destructor for pUser */
+};
+
+/*
+** A sort order can be either ASC or DESC.
+*/
+#define SQLITE_SO_ASC       0  /* Sort in ascending order */
+#define SQLITE_SO_DESC      1  /* Sort in ascending order */
+#define SQLITE_SO_UNDEFINED -1 /* No sort order specified */
+
+/*
+** Column affinity types.
+**
+** These used to have mnemonic name like 'i' for SQLITE_AFF_INTEGER and
+** 't' for SQLITE_AFF_TEXT.  But we can save a little space and improve
+** the speed a little by numbering the values consecutively.
+**
+** But rather than start with 0 or 1, we begin with 'A'.  That way,
+** when multiple affinity types are concatenated into a string and
+** used as the P4 operand, they will be more readable.
+**
+** Note also that the numeric types are grouped together so that testing
+** for a numeric type is a single comparison.  And the BLOB type is first.
+*/
+#define SQLITE_AFF_BLOB     'A'
+#define SQLITE_AFF_TEXT     'B'
+#define SQLITE_AFF_NUMERIC  'C'
+#define SQLITE_AFF_INTEGER  'D'
+#define SQLITE_AFF_REAL     'E'
+
+#define sqlite3IsNumericAffinity(X)  ((X)>=SQLITE_AFF_NUMERIC)
+
+/*
+** The SQLITE_AFF_MASK values masks off the significant bits of an
+** affinity value.
+*/
+#define SQLITE_AFF_MASK     0x47
+
+/*
+** Additional bit values that can be ORed with an affinity without
+** changing the affinity.
+**
+** The SQLITE_NOTNULL flag is a combination of NULLEQ and JUMPIFNULL.
+** It causes an assert() to fire if either operand to a comparison
+** operator is NULL.  It is added to certain comparison operators to
+** prove that the operands are always NOT NULL.
+*/
+#define SQLITE_KEEPNULL     0x08  /* Used by vector == or <> */
+#define SQLITE_JUMPIFNULL   0x10  /* jumps if either operand is NULL */
+#define SQLITE_STOREP2      0x20  /* Store result in reg[P2] rather than jump */
+#define SQLITE_NULLEQ       0x80  /* NULL=NULL */
+#define SQLITE_NOTNULL      0x90  /* Assert that operands are never NULL */
+
+/*
+** An object of this type is created for each virtual table present in
+** the database schema.
+**
+** If the database schema is shared, then there is one instance of this
+** structure for each database connection (sqlite3*) that uses the shared
+** schema. This is because each database connection requires its own unique
+** instance of the sqlite3_vtab* handle used to access the virtual table
+** implementation. sqlite3_vtab* handles can not be shared between
+** database connections, even when the rest of the in-memory database
+** schema is shared, as the implementation often stores the database
+** connection handle passed to it via the xConnect() or xCreate() method
+** during initialization internally. This database connection handle may
+** then be used by the virtual table implementation to access real tables
+** within the database. So that they appear as part of the callers
+** transaction, these accesses need to be made via the same database
+** connection as that used to execute SQL operations on the virtual table.
+**
+** All VTable objects that correspond to a single table in a shared
+** database schema are initially stored in a linked-list pointed to by
+** the Table.pVTable member variable of the corresponding Table object.
+** When an sqlite3_prepare() operation is required to access the virtual
+** table, it searches the list for the VTable that corresponds to the
+** database connection doing the preparing so as to use the correct
+** sqlite3_vtab* handle in the compiled query.
+**
+** When an in-memory Table object is deleted (for example when the
+** schema is being reloaded for some reason), the VTable objects are not
+** deleted and the sqlite3_vtab* handles are not xDisconnect()ed
+** immediately. Instead, they are moved from the Table.pVTable list to
+** another linked list headed by the sqlite3.pDisconnect member of the
+** corresponding sqlite3 structure. They are then deleted/xDisconnected
+** next time a statement is prepared using said sqlite3*. This is done
+** to avoid deadlock issues involving multiple sqlite3.mutex mutexes.
+** Refer to comments above function sqlite3VtabUnlockList() for an
+** explanation as to why it is safe to add an entry to an sqlite3.pDisconnect
+** list without holding the corresponding sqlite3.mutex mutex.
+**
+** The memory for objects of this type is always allocated by
+** sqlite3DbMalloc(), using the connection handle stored in VTable.db as
+** the first argument.
+*/
+struct VTable {
+  sqlite3 *db;              /* Database connection associated with this table */
+  Module *pMod;             /* Pointer to module implementation */
+  sqlite3_vtab *pVtab;      /* Pointer to vtab instance */
+  int nRef;                 /* Number of pointers to this structure */
+  u8 bConstraint;           /* True if constraints are supported */
+  int iSavepoint;           /* Depth of the SAVEPOINT stack */
+  VTable *pNext;            /* Next in linked list (see above) */
+};
+
+/*
+** The schema for each SQL table and view is represented in memory
+** by an instance of the following structure.
+*/
+struct Table {
+  char *zName;         /* Name of the table or view */
+  Column *aCol;        /* Information about each column */
+  Index *pIndex;       /* List of SQL indexes on this table. */
+  Select *pSelect;     /* NULL for tables.  Points to definition if a view. */
+  FKey *pFKey;         /* Linked list of all foreign keys in this table */
+  char *zColAff;       /* String defining the affinity of each column */
+  ExprList *pCheck;    /* All CHECK constraints */
+                       /*   ... also used as column name list in a VIEW */
+  int tnum;            /* Root BTree page for this table */
+  i16 iPKey;           /* If not negative, use aCol[iPKey] as the rowid */
+  i16 nCol;            /* Number of columns in this table */
+  u16 nRef;            /* Number of pointers to this Table */
+  LogEst nRowLogEst;   /* Estimated rows in table - from sqlite_stat1 table */
+  LogEst szTabRow;     /* Estimated size of each table row in bytes */
+#ifdef SQLITE_ENABLE_COSTMULT
+  LogEst costMult;     /* Cost multiplier for using this table */
+#endif
+  u8 tabFlags;         /* Mask of TF_* values */
+  u8 keyConf;          /* What to do in case of uniqueness conflict on iPKey */
+#ifndef SQLITE_OMIT_ALTERTABLE
+  int addColOffset;    /* Offset in CREATE TABLE stmt to add a new column */
+#endif
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  int nModuleArg;      /* Number of arguments to the module */
+  char **azModuleArg;  /* 0: module 1: schema 2: vtab name 3...: args */
+  VTable *pVTable;     /* List of VTable objects. */
+#endif
+  Trigger *pTrigger;   /* List of triggers stored in pSchema */
+  Schema *pSchema;     /* Schema that contains this table */
+  Table *pNextZombie;  /* Next on the Parse.pZombieTab list */
+};
+
+/*
+** Allowed values for Table.tabFlags.
+**
+** TF_OOOHidden applies to tables or view that have hidden columns that are
+** followed by non-hidden columns.  Example:  "CREATE VIRTUAL TABLE x USING
+** vtab1(a HIDDEN, b);".  Since "b" is a non-hidden column but "a" is hidden,
+** the TF_OOOHidden attribute would apply in this case.  Such tables require
+** special handling during INSERT processing.
+*/
+#define TF_Readonly        0x01    /* Read-only system table */
+#define TF_Ephemeral       0x02    /* An ephemeral table */
+#define TF_HasPrimaryKey   0x04    /* Table has a primary key */
+#define TF_Autoincrement   0x08    /* Integer primary key is autoincrement */
+#define TF_Virtual         0x10    /* Is a virtual table */
+#define TF_WithoutRowid    0x20    /* No rowid.  PRIMARY KEY is the key */
+#define TF_NoVisibleRowid  0x40    /* No user-visible "rowid" column */
+#define TF_OOOHidden       0x80    /* Out-of-Order hidden columns */
+
+
+/*
+** Test to see whether or not a table is a virtual table.  This is
+** done as a macro so that it will be optimized out when virtual
+** table support is omitted from the build.
+*/
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+#  define IsVirtual(X)      (((X)->tabFlags & TF_Virtual)!=0)
+#else
+#  define IsVirtual(X)      0
+#endif
+
+/*
+** Macros to determine if a column is hidden.  IsOrdinaryHiddenColumn()
+** only works for non-virtual tables (ordinary tables and views) and is
+** always false unless SQLITE_ENABLE_HIDDEN_COLUMNS is defined.  The
+** IsHiddenColumn() macro is general purpose.
+*/
+#if defined(SQLITE_ENABLE_HIDDEN_COLUMNS)
+#  define IsHiddenColumn(X)         (((X)->colFlags & COLFLAG_HIDDEN)!=0)
+#  define IsOrdinaryHiddenColumn(X) (((X)->colFlags & COLFLAG_HIDDEN)!=0)
+#elif !defined(SQLITE_OMIT_VIRTUALTABLE)
+#  define IsHiddenColumn(X)         (((X)->colFlags & COLFLAG_HIDDEN)!=0)
+#  define IsOrdinaryHiddenColumn(X) 0
+#else
+#  define IsHiddenColumn(X)         0
+#  define IsOrdinaryHiddenColumn(X) 0
+#endif
+
+
+/* Does the table have a rowid */
+#define HasRowid(X)     (((X)->tabFlags & TF_WithoutRowid)==0)
+#define VisibleRowid(X) (((X)->tabFlags & TF_NoVisibleRowid)==0)
+
+/*
+** Each foreign key constraint is an instance of the following structure.
+**
+** A foreign key is associated with two tables.  The "from" table is
+** the table that contains the REFERENCES clause that creates the foreign
+** key.  The "to" table is the table that is named in the REFERENCES clause.
+** Consider this example:
+**
+**     CREATE TABLE ex1(
+**       a INTEGER PRIMARY KEY,
+**       b INTEGER CONSTRAINT fk1 REFERENCES ex2(x)
+**     );
+**
+** For foreign key "fk1", the from-table is "ex1" and the to-table is "ex2".
+** Equivalent names:
+**
+**     from-table == child-table
+**       to-table == parent-table
+**
+** Each REFERENCES clause generates an instance of the following structure
+** which is attached to the from-table.  The to-table need not exist when
+** the from-table is created.  The existence of the to-table is not checked.
+**
+** The list of all parents for child Table X is held at X.pFKey.
+**
+** A list of all children for a table named Z (which might not even exist)
+** is held in Schema.fkeyHash with a hash key of Z.
+*/
+struct FKey {
+  Table *pFrom;     /* Table containing the REFERENCES clause (aka: Child) */
+  FKey *pNextFrom;  /* Next FKey with the same in pFrom. Next parent of pFrom */
+  char *zTo;        /* Name of table that the key points to (aka: Parent) */
+  FKey *pNextTo;    /* Next with the same zTo. Next child of zTo. */
+  FKey *pPrevTo;    /* Previous with the same zTo */
+  int nCol;         /* Number of columns in this key */
+  /* EV: R-30323-21917 */
+  u8 isDeferred;       /* True if constraint checking is deferred till COMMIT */
+  u8 aAction[2];        /* ON DELETE and ON UPDATE actions, respectively */
+  Trigger *apTrigger[2];/* Triggers for aAction[] actions */
+  struct sColMap {      /* Mapping of columns in pFrom to columns in zTo */
+    int iFrom;            /* Index of column in pFrom */
+    char *zCol;           /* Name of column in zTo.  If NULL use PRIMARY KEY */
+  } aCol[1];            /* One entry for each of nCol columns */
+};
+
+/*
+** SQLite supports many different ways to resolve a constraint
+** error.  ROLLBACK processing means that a constraint violation
+** causes the operation in process to fail and for the current transaction
+** to be rolled back.  ABORT processing means the operation in process
+** fails and any prior changes from that one operation are backed out,
+** but the transaction is not rolled back.  FAIL processing means that
+** the operation in progress stops and returns an error code.  But prior
+** changes due to the same operation are not backed out and no rollback
+** occurs.  IGNORE means that the particular row that caused the constraint
+** error is not inserted or updated.  Processing continues and no error
+** is returned.  REPLACE means that preexisting database rows that caused
+** a UNIQUE constraint violation are removed so that the new insert or
+** update can proceed.  Processing continues and no error is reported.
+**
+** RESTRICT, SETNULL, and CASCADE actions apply only to foreign keys.
+** RESTRICT is the same as ABORT for IMMEDIATE foreign keys and the
+** same as ROLLBACK for DEFERRED keys.  SETNULL means that the foreign
+** key is set to NULL.  CASCADE means that a DELETE or UPDATE of the
+** referenced table row is propagated into the row that holds the
+** foreign key.
+**
+** The following symbolic values are used to record which type
+** of action to take.
+*/
+#define OE_None     0   /* There is no constraint to check */
+#define OE_Rollback 1   /* Fail the operation and rollback the transaction */
+#define OE_Abort    2   /* Back out changes but do no rollback transaction */
+#define OE_Fail     3   /* Stop the operation but leave all prior changes */
+#define OE_Ignore   4   /* Ignore the error. Do not do the INSERT or UPDATE */
+#define OE_Replace  5   /* Delete existing record, then do INSERT or UPDATE */
+
+#define OE_Restrict 6   /* OE_Abort for IMMEDIATE, OE_Rollback for DEFERRED */
+#define OE_SetNull  7   /* Set the foreign key value to NULL */
+#define OE_SetDflt  8   /* Set the foreign key value to its default */
+#define OE_Cascade  9   /* Cascade the changes */
+
+#define OE_Default  10  /* Do whatever the default action is */
+
+
+/*
+** An instance of the following structure is passed as the first
+** argument to sqlite3VdbeKeyCompare and is used to control the
+** comparison of the two index keys.
+**
+** Note that aSortOrder[] and aColl[] have nField+1 slots.  There
+** are nField slots for the columns of an index then one extra slot
+** for the rowid at the end.
+*/
+struct KeyInfo {
+  u32 nRef;           /* Number of references to this KeyInfo object */
+  u8 enc;             /* Text encoding - one of the SQLITE_UTF* values */
+  u16 nField;         /* Number of key columns in the index */
+  u16 nXField;        /* Number of columns beyond the key columns */
+  sqlite3 *db;        /* The database connection */
+  u8 *aSortOrder;     /* Sort order for each column. */
+  CollSeq *aColl[1];  /* Collating sequence for each term of the key */
+};
+
+/*
+** This object holds a record which has been parsed out into individual
+** fields, for the purposes of doing a comparison.
+**
+** A record is an object that contains one or more fields of data.
+** Records are used to store the content of a table row and to store
+** the key of an index.  A blob encoding of a record is created by
+** the OP_MakeRecord opcode of the VDBE and is disassembled by the
+** OP_Column opcode.
+**
+** An instance of this object serves as a "key" for doing a search on
+** an index b+tree. The goal of the search is to find the entry that
+** is closed to the key described by this object.  This object might hold
+** just a prefix of the key.  The number of fields is given by
+** pKeyInfo->nField.
+**
+** The r1 and r2 fields are the values to return if this key is less than
+** or greater than a key in the btree, respectively.  These are normally
+** -1 and +1 respectively, but might be inverted to +1 and -1 if the b-tree
+** is in DESC order.
+**
+** The key comparison functions actually return default_rc when they find
+** an equals comparison.  default_rc can be -1, 0, or +1.  If there are
+** multiple entries in the b-tree with the same key (when only looking
+** at the first pKeyInfo->nFields,) then default_rc can be set to -1 to
+** cause the search to find the last match, or +1 to cause the search to
+** find the first match.
+**
+** The key comparison functions will set eqSeen to true if they ever
+** get and equal results when comparing this structure to a b-tree record.
+** When default_rc!=0, the search might end up on the record immediately
+** before the first match or immediately after the last match.  The
+** eqSeen field will indicate whether or not an exact match exists in the
+** b-tree.
+*/
+struct UnpackedRecord {
+  KeyInfo *pKeyInfo;  /* Collation and sort-order information */
+  Mem *aMem;          /* Values */
+  u16 nField;         /* Number of entries in apMem[] */
+  i8 default_rc;      /* Comparison result if keys are equal */
+  u8 errCode;         /* Error detected by xRecordCompare (CORRUPT or NOMEM) */
+  i8 r1;              /* Value to return if (lhs > rhs) */
+  i8 r2;              /* Value to return if (rhs < lhs) */
+  u8 eqSeen;          /* True if an equality comparison has been seen */
+};
+
+
+/*
+** Each SQL index is represented in memory by an
+** instance of the following structure.
+**
+** The columns of the table that are to be indexed are described
+** by the aiColumn[] field of this structure.  For example, suppose
+** we have the following table and index:
+**
+**     CREATE TABLE Ex1(c1 int, c2 int, c3 text);
+**     CREATE INDEX Ex2 ON Ex1(c3,c1);
+**
+** In the Table structure describing Ex1, nCol==3 because there are
+** three columns in the table.  In the Index structure describing
+** Ex2, nColumn==2 since 2 of the 3 columns of Ex1 are indexed.
+** The value of aiColumn is {2, 0}.  aiColumn[0]==2 because the
+** first column to be indexed (c3) has an index of 2 in Ex1.aCol[].
+** The second column to be indexed (c1) has an index of 0 in
+** Ex1.aCol[], hence Ex2.aiColumn[1]==0.
+**
+** The Index.onError field determines whether or not the indexed columns
+** must be unique and what to do if they are not.  When Index.onError=OE_None,
+** it means this is not a unique index.  Otherwise it is a unique index
+** and the value of Index.onError indicate the which conflict resolution
+** algorithm to employ whenever an attempt is made to insert a non-unique
+** element.
+**
+** While parsing a CREATE TABLE or CREATE INDEX statement in order to
+** generate VDBE code (as opposed to parsing one read from an sqlite_master
+** table as part of parsing an existing database schema), transient instances
+** of this structure may be created. In this case the Index.tnum variable is
+** used to store the address of a VDBE instruction, not a database page
+** number (it cannot - the database page is not allocated until the VDBE
+** program is executed). See convertToWithoutRowidTable() for details.
+*/
+struct Index {
+  char *zName;             /* Name of this index */
+  i16 *aiColumn;           /* Which columns are used by this index.  1st is 0 */
+  LogEst *aiRowLogEst;     /* From ANALYZE: Est. rows selected by each column */
+  Table *pTable;           /* The SQL table being indexed */
+  char *zColAff;           /* String defining the affinity of each column */
+  Index *pNext;            /* The next index associated with the same table */
+  Schema *pSchema;         /* Schema containing this index */
+  u8 *aSortOrder;          /* for each column: True==DESC, False==ASC */
+  const char **azColl;     /* Array of collation sequence names for index */
+  Expr *pPartIdxWhere;     /* WHERE clause for partial indices */
+  ExprList *aColExpr;      /* Column expressions */
+  int tnum;                /* DB Page containing root of this index */
+  LogEst szIdxRow;         /* Estimated average row size in bytes */
+  u16 nKeyCol;             /* Number of columns forming the key */
+  u16 nColumn;             /* Number of columns stored in the index */
+  u8 onError;              /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
+  unsigned idxType:2;      /* 1==UNIQUE, 2==PRIMARY KEY, 0==CREATE INDEX */
+  unsigned bUnordered:1;   /* Use this index for == or IN queries only */
+  unsigned uniqNotNull:1;  /* True if UNIQUE and NOT NULL for all columns */
+  unsigned isResized:1;    /* True if resizeIndexObject() has been called */
+  unsigned isCovering:1;   /* True if this is a covering index */
+  unsigned noSkipScan:1;   /* Do not try to use skip-scan if true */
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  int nSample;             /* Number of elements in aSample[] */
+  int nSampleCol;          /* Size of IndexSample.anEq[] and so on */
+  tRowcnt *aAvgEq;         /* Average nEq values for keys not in aSample */
+  IndexSample *aSample;    /* Samples of the left-most key */
+  tRowcnt *aiRowEst;       /* Non-logarithmic stat1 data for this index */
+  tRowcnt nRowEst0;        /* Non-logarithmic number of rows in the index */
+#endif
+};
+
+/*
+** Allowed values for Index.idxType
+*/
+#define SQLITE_IDXTYPE_APPDEF      0   /* Created using CREATE INDEX */
+#define SQLITE_IDXTYPE_UNIQUE      1   /* Implements a UNIQUE constraint */
+#define SQLITE_IDXTYPE_PRIMARYKEY  2   /* Is the PRIMARY KEY for the table */
+
+/* Return true if index X is a PRIMARY KEY index */
+#define IsPrimaryKeyIndex(X)  ((X)->idxType==SQLITE_IDXTYPE_PRIMARYKEY)
+
+/* Return true if index X is a UNIQUE index */
+#define IsUniqueIndex(X)      ((X)->onError!=OE_None)
+
+/* The Index.aiColumn[] values are normally positive integer.  But
+** there are some negative values that have special meaning:
+*/
+#define XN_ROWID     (-1)     /* Indexed column is the rowid */
+#define XN_EXPR      (-2)     /* Indexed column is an expression */
+
+/*
+** Each sample stored in the sqlite_stat3 table is represented in memory
+** using a structure of this type.  See documentation at the top of the
+** analyze.c source file for additional information.
+*/
+struct IndexSample {
+  void *p;          /* Pointer to sampled record */
+  int n;            /* Size of record in bytes */
+  tRowcnt *anEq;    /* Est. number of rows where the key equals this sample */
+  tRowcnt *anLt;    /* Est. number of rows where key is less than this sample */
+  tRowcnt *anDLt;   /* Est. number of distinct keys less than this sample */
+};
+
+/*
+** Each token coming out of the lexer is an instance of
+** this structure.  Tokens are also used as part of an expression.
+**
+** Note if Token.z==0 then Token.dyn and Token.n are undefined and
+** may contain random values.  Do not make any assumptions about Token.dyn
+** and Token.n when Token.z==0.
+*/
+struct Token {
+  const char *z;     /* Text of the token.  Not NULL-terminated! */
+  unsigned int n;    /* Number of characters in this token */
+};
+
+/*
+** An instance of this structure contains information needed to generate
+** code for a SELECT that contains aggregate functions.
+**
+** If Expr.op==TK_AGG_COLUMN or TK_AGG_FUNCTION then Expr.pAggInfo is a
+** pointer to this structure.  The Expr.iColumn field is the index in
+** AggInfo.aCol[] or AggInfo.aFunc[] of information needed to generate
+** code for that node.
+**
+** AggInfo.pGroupBy and AggInfo.aFunc.pExpr point to fields within the
+** original Select structure that describes the SELECT statement.  These
+** fields do not need to be freed when deallocating the AggInfo structure.
+*/
+struct AggInfo {
+  u8 directMode;          /* Direct rendering mode means take data directly
+                          ** from source tables rather than from accumulators */
+  u8 useSortingIdx;       /* In direct mode, reference the sorting index rather
+                          ** than the source table */
+  int sortingIdx;         /* Cursor number of the sorting index */
+  int sortingIdxPTab;     /* Cursor number of pseudo-table */
+  int nSortingColumn;     /* Number of columns in the sorting index */
+  int mnReg, mxReg;       /* Range of registers allocated for aCol and aFunc */
+  ExprList *pGroupBy;     /* The group by clause */
+  struct AggInfo_col {    /* For each column used in source tables */
+    Table *pTab;             /* Source table */
+    int iTable;              /* Cursor number of the source table */
+    int iColumn;             /* Column number within the source table */
+    int iSorterColumn;       /* Column number in the sorting index */
+    int iMem;                /* Memory location that acts as accumulator */
+    Expr *pExpr;             /* The original expression */
+  } *aCol;
+  int nColumn;            /* Number of used entries in aCol[] */
+  int nAccumulator;       /* Number of columns that show through to the output.
+                          ** Additional columns are used only as parameters to
+                          ** aggregate functions */
+  struct AggInfo_func {   /* For each aggregate function */
+    Expr *pExpr;             /* Expression encoding the function */
+    FuncDef *pFunc;          /* The aggregate function implementation */
+    int iMem;                /* Memory location that acts as accumulator */
+    int iDistinct;           /* Ephemeral table used to enforce DISTINCT */
+  } *aFunc;
+  int nFunc;              /* Number of entries in aFunc[] */
+};
+
+/*
+** The datatype ynVar is a signed integer, either 16-bit or 32-bit.
+** Usually it is 16-bits.  But if SQLITE_MAX_VARIABLE_NUMBER is greater
+** than 32767 we have to make it 32-bit.  16-bit is preferred because
+** it uses less memory in the Expr object, which is a big memory user
+** in systems with lots of prepared statements.  And few applications
+** need more than about 10 or 20 variables.  But some extreme users want
+** to have prepared statements with over 32767 variables, and for them
+** the option is available (at compile-time).
+*/
+#if SQLITE_MAX_VARIABLE_NUMBER<=32767
+typedef i16 ynVar;
+#else
+typedef int ynVar;
+#endif
+
+/*
+** Each node of an expression in the parse tree is an instance
+** of this structure.
+**
+** Expr.op is the opcode. The integer parser token codes are reused
+** as opcodes here. For example, the parser defines TK_GE to be an integer
+** code representing the ">=" operator. This same integer code is reused
+** to represent the greater-than-or-equal-to operator in the expression
+** tree.
+**
+** If the expression is an SQL literal (TK_INTEGER, TK_FLOAT, TK_BLOB,
+** or TK_STRING), then Expr.token contains the text of the SQL literal. If
+** the expression is a variable (TK_VARIABLE), then Expr.token contains the
+** variable name. Finally, if the expression is an SQL function (TK_FUNCTION),
+** then Expr.token contains the name of the function.
+**
+** Expr.pRight and Expr.pLeft are the left and right subexpressions of a
+** binary operator. Either or both may be NULL.
+**
+** Expr.x.pList is a list of arguments if the expression is an SQL function,
+** a CASE expression or an IN expression of the form "<lhs> IN (<y>, <z>...)".
+** Expr.x.pSelect is used if the expression is a sub-select or an expression of
+** the form "<lhs> IN (SELECT ...)". If the EP_xIsSelect bit is set in the
+** Expr.flags mask, then Expr.x.pSelect is valid. Otherwise, Expr.x.pList is
+** valid.
+**
+** An expression of the form ID or ID.ID refers to a column in a table.
+** For such expressions, Expr.op is set to TK_COLUMN and Expr.iTable is
+** the integer cursor number of a VDBE cursor pointing to that table and
+** Expr.iColumn is the column number for the specific column.  If the
+** expression is used as a result in an aggregate SELECT, then the
+** value is also stored in the Expr.iAgg column in the aggregate so that
+** it can be accessed after all aggregates are computed.
+**
+** If the expression is an unbound variable marker (a question mark
+** character '?' in the original SQL) then the Expr.iTable holds the index
+** number for that variable.
+**
+** If the expression is a subquery then Expr.iColumn holds an integer
+** register number containing the result of the subquery.  If the
+** subquery gives a constant result, then iTable is -1.  If the subquery
+** gives a different answer at different times during statement processing
+** then iTable is the address of a subroutine that computes the subquery.
+**
+** If the Expr is of type OP_Column, and the table it is selecting from
+** is a disk table or the "old.*" pseudo-table, then pTab points to the
+** corresponding table definition.
+**
+** ALLOCATION NOTES:
+**
+** Expr objects can use a lot of memory space in database schema.  To
+** help reduce memory requirements, sometimes an Expr object will be
+** truncated.  And to reduce the number of memory allocations, sometimes
+** two or more Expr objects will be stored in a single memory allocation,
+** together with Expr.zToken strings.
+**
+** If the EP_Reduced and EP_TokenOnly flags are set when
+** an Expr object is truncated.  When EP_Reduced is set, then all
+** the child Expr objects in the Expr.pLeft and Expr.pRight subtrees
+** are contained within the same memory allocation.  Note, however, that
+** the subtrees in Expr.x.pList or Expr.x.pSelect are always separately
+** allocated, regardless of whether or not EP_Reduced is set.
+*/
+struct Expr {
+  u8 op;                 /* Operation performed by this node */
+  char affinity;         /* The affinity of the column or 0 if not a column */
+  u32 flags;             /* Various flags.  EP_* See below */
+  union {
+    char *zToken;          /* Token value. Zero terminated and dequoted */
+    int iValue;            /* Non-negative integer value if EP_IntValue */
+  } u;
+
+  /* If the EP_TokenOnly flag is set in the Expr.flags mask, then no
+  ** space is allocated for the fields below this point. An attempt to
+  ** access them will result in a segfault or malfunction.
+  *********************************************************************/
+
+  Expr *pLeft;           /* Left subnode */
+  Expr *pRight;          /* Right subnode */
+  union {
+    ExprList *pList;     /* op = IN, EXISTS, SELECT, CASE, FUNCTION, BETWEEN */
+    Select *pSelect;     /* EP_xIsSelect and op = IN, EXISTS, SELECT */
+  } x;
+
+  /* If the EP_Reduced flag is set in the Expr.flags mask, then no
+  ** space is allocated for the fields below this point. An attempt to
+  ** access them will result in a segfault or malfunction.
+  *********************************************************************/
+
+#if SQLITE_MAX_EXPR_DEPTH>0
+  int nHeight;           /* Height of the tree headed by this node */
+#endif
+  int iTable;            /* TK_COLUMN: cursor number of table holding column
+                         ** TK_REGISTER: register number
+                         ** TK_TRIGGER: 1 -> new, 0 -> old
+                         ** EP_Unlikely:  134217728 times likelihood
+                         ** TK_SELECT: 1st register of result vector */
+  ynVar iColumn;         /* TK_COLUMN: column index.  -1 for rowid.
+                         ** TK_VARIABLE: variable number (always >= 1).
+                         ** TK_SELECT_COLUMN: column of the result vector */
+  i16 iAgg;              /* Which entry in pAggInfo->aCol[] or ->aFunc[] */
+  i16 iRightJoinTable;   /* If EP_FromJoin, the right table of the join */
+  u8 op2;                /* TK_REGISTER: original value of Expr.op
+                         ** TK_COLUMN: the value of p5 for OP_Column
+                         ** TK_AGG_FUNCTION: nesting depth */
+  AggInfo *pAggInfo;     /* Used by TK_AGG_COLUMN and TK_AGG_FUNCTION */
+  Table *pTab;           /* Table for TK_COLUMN expressions. */
+};
+
+/*
+** The following are the meanings of bits in the Expr.flags field.
+*/
+#define EP_FromJoin  0x000001 /* Originates in ON/USING clause of outer join */
+#define EP_Agg       0x000002 /* Contains one or more aggregate functions */
+#define EP_Resolved  0x000004 /* IDs have been resolved to COLUMNs */
+#define EP_Error     0x000008 /* Expression contains one or more errors */
+#define EP_Distinct  0x000010 /* Aggregate function with DISTINCT keyword */
+#define EP_VarSelect 0x000020 /* pSelect is correlated, not constant */
+#define EP_DblQuoted 0x000040 /* token.z was originally in "..." */
+#define EP_InfixFunc 0x000080 /* True for an infix function: LIKE, GLOB, etc */
+#define EP_Collate   0x000100 /* Tree contains a TK_COLLATE operator */
+#define EP_Generic   0x000200 /* Ignore COLLATE or affinity on this tree */
+#define EP_IntValue  0x000400 /* Integer value contained in u.iValue */
+#define EP_xIsSelect 0x000800 /* x.pSelect is valid (otherwise x.pList is) */
+#define EP_Skip      0x001000 /* COLLATE, AS, or UNLIKELY */
+#define EP_Reduced   0x002000 /* Expr struct EXPR_REDUCEDSIZE bytes only */
+#define EP_TokenOnly 0x004000 /* Expr struct EXPR_TOKENONLYSIZE bytes only */
+#define EP_Static    0x008000 /* Held in memory not obtained from malloc() */
+#define EP_MemToken  0x010000 /* Need to sqlite3DbFree() Expr.zToken */
+#define EP_NoReduce  0x020000 /* Cannot EXPRDUP_REDUCE this Expr */
+#define EP_Unlikely  0x040000 /* unlikely() or likelihood() function */
+#define EP_ConstFunc 0x080000 /* A SQLITE_FUNC_CONSTANT or _SLOCHNG function */
+#define EP_CanBeNull 0x100000 /* Can be null despite NOT NULL constraint */
+#define EP_Subquery  0x200000 /* Tree contains a TK_SELECT operator */
+#define EP_Alias     0x400000 /* Is an alias for a result set column */
+#define EP_Leaf      0x800000 /* Expr.pLeft, .pRight, .u.pSelect all NULL */
+
+/*
+** Combinations of two or more EP_* flags
+*/
+#define EP_Propagate (EP_Collate|EP_Subquery) /* Propagate these bits up tree */
+
+/*
+** These macros can be used to test, set, or clear bits in the
+** Expr.flags field.
+*/
+#define ExprHasProperty(E,P)     (((E)->flags&(P))!=0)
+#define ExprHasAllProperty(E,P)  (((E)->flags&(P))==(P))
+#define ExprSetProperty(E,P)     (E)->flags|=(P)
+#define ExprClearProperty(E,P)   (E)->flags&=~(P)
+
+/* The ExprSetVVAProperty() macro is used for Verification, Validation,
+** and Accreditation only.  It works like ExprSetProperty() during VVA
+** processes but is a no-op for delivery.
+*/
+#ifdef SQLITE_DEBUG
+# define ExprSetVVAProperty(E,P)  (E)->flags|=(P)
+#else
+# define ExprSetVVAProperty(E,P)
+#endif
+
+/*
+** Macros to determine the number of bytes required by a normal Expr
+** struct, an Expr struct with the EP_Reduced flag set in Expr.flags
+** and an Expr struct with the EP_TokenOnly flag set.
+*/
+#define EXPR_FULLSIZE           sizeof(Expr)           /* Full size */
+#define EXPR_REDUCEDSIZE        offsetof(Expr,iTable)  /* Common features */
+#define EXPR_TOKENONLYSIZE      offsetof(Expr,pLeft)   /* Fewer features */
+
+/*
+** Flags passed to the sqlite3ExprDup() function. See the header comment
+** above sqlite3ExprDup() for details.
+*/
+#define EXPRDUP_REDUCE         0x0001  /* Used reduced-size Expr nodes */
+
+/*
+** A list of expressions.  Each expression may optionally have a
+** name.  An expr/name combination can be used in several ways, such
+** as the list of "expr AS ID" fields following a "SELECT" or in the
+** list of "ID = expr" items in an UPDATE.  A list of expressions can
+** also be used as the argument to a function, in which case the a.zName
+** field is not used.
+**
+** By default the Expr.zSpan field holds a human-readable description of
+** the expression that is used in the generation of error messages and
+** column labels.  In this case, Expr.zSpan is typically the text of a
+** column expression as it exists in a SELECT statement.  However, if
+** the bSpanIsTab flag is set, then zSpan is overloaded to mean the name
+** of the result column in the form: DATABASE.TABLE.COLUMN.  This later
+** form is used for name resolution with nested FROM clauses.
+*/
+struct ExprList {
+  int nExpr;             /* Number of expressions on the list */
+  struct ExprList_item { /* For each expression in the list */
+    Expr *pExpr;            /* The list of expressions */
+    char *zName;            /* Token associated with this expression */
+    char *zSpan;            /* Original text of the expression */
+    u8 sortOrder;           /* 1 for DESC or 0 for ASC */
+    unsigned done :1;       /* A flag to indicate when processing is finished */
+    unsigned bSpanIsTab :1; /* zSpan holds DB.TABLE.COLUMN */
+    unsigned reusable :1;   /* Constant expression is reusable */
+    union {
+      struct {
+        u16 iOrderByCol;      /* For ORDER BY, column number in result set */
+        u16 iAlias;           /* Index into Parse.aAlias[] for zName */
+      } x;
+      int iConstExprReg;      /* Register in which Expr value is cached */
+    } u;
+  } *a;                  /* Alloc a power of two greater or equal to nExpr */
+};
+
+/*
+** An instance of this structure is used by the parser to record both
+** the parse tree for an expression and the span of input text for an
+** expression.
+*/
+struct ExprSpan {
+  Expr *pExpr;          /* The expression parse tree */
+  const char *zStart;   /* First character of input text */
+  const char *zEnd;     /* One character past the end of input text */
+};
+
+/*
+** An instance of this structure can hold a simple list of identifiers,
+** such as the list "a,b,c" in the following statements:
+**
+**      INSERT INTO t(a,b,c) VALUES ...;
+**      CREATE INDEX idx ON t(a,b,c);
+**      CREATE TRIGGER trig BEFORE UPDATE ON t(a,b,c) ...;
+**
+** The IdList.a.idx field is used when the IdList represents the list of
+** column names after a table name in an INSERT statement.  In the statement
+**
+**     INSERT INTO t(a,b,c) ...
+**
+** If "a" is the k-th column of table "t", then IdList.a[0].idx==k.
+*/
+struct IdList {
+  struct IdList_item {
+    char *zName;      /* Name of the identifier */
+    int idx;          /* Index in some Table.aCol[] of a column named zName */
+  } *a;
+  int nId;         /* Number of identifiers on the list */
+};
+
+/*
+** The bitmask datatype defined below is used for various optimizations.
+**
+** Changing this from a 64-bit to a 32-bit type limits the number of
+** tables in a join to 32 instead of 64.  But it also reduces the size
+** of the library by 738 bytes on ix86.
+*/
+#ifdef SQLITE_BITMASK_TYPE
+  typedef SQLITE_BITMASK_TYPE Bitmask;
+#else
+  typedef u64 Bitmask;
+#endif
+
+/*
+** The number of bits in a Bitmask.  "BMS" means "BitMask Size".
+*/
+#define BMS  ((int)(sizeof(Bitmask)*8))
+
+/*
+** A bit in a Bitmask
+*/
+#define MASKBIT(n)   (((Bitmask)1)<<(n))
+#define MASKBIT32(n) (((unsigned int)1)<<(n))
+#define ALLBITS      ((Bitmask)-1)
+
+/*
+** The following structure describes the FROM clause of a SELECT statement.
+** Each table or subquery in the FROM clause is a separate element of
+** the SrcList.a[] array.
+**
+** With the addition of multiple database support, the following structure
+** can also be used to describe a particular table such as the table that
+** is modified by an INSERT, DELETE, or UPDATE statement.  In standard SQL,
+** such a table must be a simple name: ID.  But in SQLite, the table can
+** now be identified by a database name, a dot, then the table name: ID.ID.
+**
+** The jointype starts out showing the join type between the current table
+** and the next table on the list.  The parser builds the list this way.
+** But sqlite3SrcListShiftJoinType() later shifts the jointypes so that each
+** jointype expresses the join between the table and the previous table.
+**
+** In the colUsed field, the high-order bit (bit 63) is set if the table
+** contains more than 63 columns and the 64-th or later column is used.
+*/
+struct SrcList {
+  int nSrc;        /* Number of tables or subqueries in the FROM clause */
+  u32 nAlloc;      /* Number of entries allocated in a[] below */
+  struct SrcList_item {
+    Schema *pSchema;  /* Schema to which this item is fixed */
+    char *zDatabase;  /* Name of database holding this table */
+    char *zName;      /* Name of the table */
+    char *zAlias;     /* The "B" part of a "A AS B" phrase.  zName is the "A" */
+    Table *pTab;      /* An SQL table corresponding to zName */
+    Select *pSelect;  /* A SELECT statement used in place of a table name */
+    int addrFillSub;  /* Address of subroutine to manifest a subquery */
+    int regReturn;    /* Register holding return address of addrFillSub */
+    int regResult;    /* Registers holding results of a co-routine */
+    struct {
+      u8 jointype;      /* Type of join between this table and the previous */
+      unsigned notIndexed :1;    /* True if there is a NOT INDEXED clause */
+      unsigned isIndexedBy :1;   /* True if there is an INDEXED BY clause */
+      unsigned isTabFunc :1;     /* True if table-valued-function syntax */
+      unsigned isCorrelated :1;  /* True if sub-query is correlated */
+      unsigned viaCoroutine :1;  /* Implemented as a co-routine */
+      unsigned isRecursive :1;   /* True for recursive reference in WITH */
+    } fg;
+#ifndef SQLITE_OMIT_EXPLAIN
+    u8 iSelectId;     /* If pSelect!=0, the id of the sub-select in EQP */
+#endif
+    int iCursor;      /* The VDBE cursor number used to access this table */
+    Expr *pOn;        /* The ON clause of a join */
+    IdList *pUsing;   /* The USING clause of a join */
+    Bitmask colUsed;  /* Bit N (1<<N) set if column N of pTab is used */
+    union {
+      char *zIndexedBy;    /* Identifier from "INDEXED BY <zIndex>" clause */
+      ExprList *pFuncArg;  /* Arguments to table-valued-function */
+    } u1;
+    Index *pIBIndex;  /* Index structure corresponding to u1.zIndexedBy */
+  } a[1];             /* One entry for each identifier on the list */
+};
+
+/*
+** Permitted values of the SrcList.a.jointype field
+*/
+#define JT_INNER     0x0001    /* Any kind of inner or cross join */
+#define JT_CROSS     0x0002    /* Explicit use of the CROSS keyword */
+#define JT_NATURAL   0x0004    /* True for a "natural" join */
+#define JT_LEFT      0x0008    /* Left outer join */
+#define JT_RIGHT     0x0010    /* Right outer join */
+#define JT_OUTER     0x0020    /* The "OUTER" keyword is present */
+#define JT_ERROR     0x0040    /* unknown or unsupported join type */
+
+
+/*
+** Flags appropriate for the wctrlFlags parameter of sqlite3WhereBegin()
+** and the WhereInfo.wctrlFlags member.
+**
+** Value constraints (enforced via assert()):
+**     WHERE_USE_LIMIT  == SF_FixedLimit
+*/
+#define WHERE_ORDERBY_NORMAL   0x0000 /* No-op */
+#define WHERE_ORDERBY_MIN      0x0001 /* ORDER BY processing for min() func */
+#define WHERE_ORDERBY_MAX      0x0002 /* ORDER BY processing for max() func */
+#define WHERE_ONEPASS_DESIRED  0x0004 /* Want to do one-pass UPDATE/DELETE */
+#define WHERE_ONEPASS_MULTIROW 0x0008 /* ONEPASS is ok with multiple rows */
+#define WHERE_DUPLICATES_OK    0x0010 /* Ok to return a row more than once */
+#define WHERE_OR_SUBCLAUSE     0x0020 /* Processing a sub-WHERE as part of
+                                      ** the OR optimization  */
+#define WHERE_GROUPBY          0x0040 /* pOrderBy is really a GROUP BY */
+#define WHERE_DISTINCTBY       0x0080 /* pOrderby is really a DISTINCT clause */
+#define WHERE_WANT_DISTINCT    0x0100 /* All output needs to be distinct */
+#define WHERE_SORTBYGROUP      0x0200 /* Support sqlite3WhereIsSorted() */
+#define WHERE_SEEK_TABLE       0x0400 /* Do not defer seeks on main table */
+#define WHERE_ORDERBY_LIMIT    0x0800 /* ORDERBY+LIMIT on the inner loop */
+                        /*     0x1000    not currently used */
+                        /*     0x2000    not currently used */
+#define WHERE_USE_LIMIT        0x4000 /* Use the LIMIT in cost estimates */
+                        /*     0x8000    not currently used */
+
+/* Allowed return values from sqlite3WhereIsDistinct()
+*/
+#define WHERE_DISTINCT_NOOP      0  /* DISTINCT keyword not used */
+#define WHERE_DISTINCT_UNIQUE    1  /* No duplicates */
+#define WHERE_DISTINCT_ORDERED   2  /* All duplicates are adjacent */
+#define WHERE_DISTINCT_UNORDERED 3  /* Duplicates are scattered */
+
+/*
+** A NameContext defines a context in which to resolve table and column
+** names.  The context consists of a list of tables (the pSrcList) field and
+** a list of named expression (pEList).  The named expression list may
+** be NULL.  The pSrc corresponds to the FROM clause of a SELECT or
+** to the table being operated on by INSERT, UPDATE, or DELETE.  The
+** pEList corresponds to the result set of a SELECT and is NULL for
+** other statements.
+**
+** NameContexts can be nested.  When resolving names, the inner-most
+** context is searched first.  If no match is found, the next outer
+** context is checked.  If there is still no match, the next context
+** is checked.  This process continues until either a match is found
+** or all contexts are check.  When a match is found, the nRef member of
+** the context containing the match is incremented.
+**
+** Each subquery gets a new NameContext.  The pNext field points to the
+** NameContext in the parent query.  Thus the process of scanning the
+** NameContext list corresponds to searching through successively outer
+** subqueries looking for a match.
+*/
+struct NameContext {
+  Parse *pParse;       /* The parser */
+  SrcList *pSrcList;   /* One or more tables used to resolve names */
+  ExprList *pEList;    /* Optional list of result-set columns */
+  AggInfo *pAggInfo;   /* Information about aggregates at this level */
+  NameContext *pNext;  /* Next outer name context.  NULL for outermost */
+  int nRef;            /* Number of names resolved by this context */
+  int nErr;            /* Number of errors encountered while resolving names */
+  u16 ncFlags;         /* Zero or more NC_* flags defined below */
+};
+
+/*
+** Allowed values for the NameContext, ncFlags field.
+**
+** Value constraints (all checked via assert()):
+**    NC_HasAgg    == SF_HasAgg
+**    NC_MinMaxAgg == SF_MinMaxAgg == SQLITE_FUNC_MINMAX
+**
+*/
+#define NC_AllowAgg  0x0001  /* Aggregate functions are allowed here */
+#define NC_PartIdx   0x0002  /* True if resolving a partial index WHERE */
+#define NC_IsCheck   0x0004  /* True if resolving names in a CHECK constraint */
+#define NC_InAggFunc 0x0008  /* True if analyzing arguments to an agg func */
+#define NC_HasAgg    0x0010  /* One or more aggregate functions seen */
+#define NC_IdxExpr   0x0020  /* True if resolving columns of CREATE INDEX */
+#define NC_VarSelect 0x0040  /* A correlated subquery has been seen */
+#define NC_MinMaxAgg 0x1000  /* min/max aggregates seen.  See note above */
+
+/*
+** An instance of the following structure contains all information
+** needed to generate code for a single SELECT statement.
+**
+** nLimit is set to -1 if there is no LIMIT clause.  nOffset is set to 0.
+** If there is a LIMIT clause, the parser sets nLimit to the value of the
+** limit and nOffset to the value of the offset (or 0 if there is not
+** offset).  But later on, nLimit and nOffset become the memory locations
+** in the VDBE that record the limit and offset counters.
+**
+** addrOpenEphm[] entries contain the address of OP_OpenEphemeral opcodes.
+** These addresses must be stored so that we can go back and fill in
+** the P4_KEYINFO and P2 parameters later.  Neither the KeyInfo nor
+** the number of columns in P2 can be computed at the same time
+** as the OP_OpenEphm instruction is coded because not
+** enough information about the compound query is known at that point.
+** The KeyInfo for addrOpenTran[0] and [1] contains collating sequences
+** for the result set.  The KeyInfo for addrOpenEphm[2] contains collating
+** sequences for the ORDER BY clause.
+*/
+struct Select {
+  ExprList *pEList;      /* The fields of the result */
+  u8 op;                 /* One of: TK_UNION TK_ALL TK_INTERSECT TK_EXCEPT */
+  LogEst nSelectRow;     /* Estimated number of result rows */
+  u32 selFlags;          /* Various SF_* values */
+  int iLimit, iOffset;   /* Memory registers holding LIMIT & OFFSET counters */
+#if SELECTTRACE_ENABLED
+  char zSelName[12];     /* Symbolic name of this SELECT use for debugging */
+#endif
+  int addrOpenEphm[2];   /* OP_OpenEphem opcodes related to this select */
+  SrcList *pSrc;         /* The FROM clause */
+  Expr *pWhere;          /* The WHERE clause */
+  ExprList *pGroupBy;    /* The GROUP BY clause */
+  Expr *pHaving;         /* The HAVING clause */
+  ExprList *pOrderBy;    /* The ORDER BY clause */
+  Select *pPrior;        /* Prior select in a compound select statement */
+  Select *pNext;         /* Next select to the left in a compound */
+  Expr *pLimit;          /* LIMIT expression. NULL means not used. */
+  Expr *pOffset;         /* OFFSET expression. NULL means not used. */
+  With *pWith;           /* WITH clause attached to this select. Or NULL. */
+};
+
+/*
+** Allowed values for Select.selFlags.  The "SF" prefix stands for
+** "Select Flag".
+**
+** Value constraints (all checked via assert())
+**     SF_HasAgg     == NC_HasAgg
+**     SF_MinMaxAgg  == NC_MinMaxAgg     == SQLITE_FUNC_MINMAX
+**     SF_FixedLimit == WHERE_USE_LIMIT
+*/
+#define SF_Distinct       0x00001  /* Output should be DISTINCT */
+#define SF_All            0x00002  /* Includes the ALL keyword */
+#define SF_Resolved       0x00004  /* Identifiers have been resolved */
+#define SF_Aggregate      0x00008  /* Contains agg functions or a GROUP BY */
+#define SF_HasAgg         0x00010  /* Contains aggregate functions */
+#define SF_UsesEphemeral  0x00020  /* Uses the OpenEphemeral opcode */
+#define SF_Expanded       0x00040  /* sqlite3SelectExpand() called on this */
+#define SF_HasTypeInfo    0x00080  /* FROM subqueries have Table metadata */
+#define SF_Compound       0x00100  /* Part of a compound query */
+#define SF_Values         0x00200  /* Synthesized from VALUES clause */
+#define SF_MultiValue     0x00400  /* Single VALUES term with multiple rows */
+#define SF_NestedFrom     0x00800  /* Part of a parenthesized FROM clause */
+#define SF_MinMaxAgg      0x01000  /* Aggregate containing min() or max() */
+#define SF_Recursive      0x02000  /* The recursive part of a recursive CTE */
+#define SF_FixedLimit     0x04000  /* nSelectRow set by a constant LIMIT */
+#define SF_MaybeConvert   0x08000  /* Need convertCompoundSelectToSubquery() */
+#define SF_Converted      0x10000  /* By convertCompoundSelectToSubquery() */
+#define SF_IncludeHidden  0x20000  /* Include hidden columns in output */
+
+
+/*
+** The results of a SELECT can be distributed in several ways, as defined
+** by one of the following macros.  The "SRT" prefix means "SELECT Result
+** Type".
+**
+**     SRT_Union       Store results as a key in a temporary index
+**                     identified by pDest->iSDParm.
+**
+**     SRT_Except      Remove results from the temporary index pDest->iSDParm.
+**
+**     SRT_Exists      Store a 1 in memory cell pDest->iSDParm if the result
+**                     set is not empty.
+**
+**     SRT_Discard     Throw the results away.  This is used by SELECT
+**                     statements within triggers whose only purpose is
+**                     the side-effects of functions.
+**
+** All of the above are free to ignore their ORDER BY clause. Those that
+** follow must honor the ORDER BY clause.
+**
+**     SRT_Output      Generate a row of output (using the OP_ResultRow
+**                     opcode) for each row in the result set.
+**
+**     SRT_Mem         Only valid if the result is a single column.
+**                     Store the first column of the first result row
+**                     in register pDest->iSDParm then abandon the rest
+**                     of the query.  This destination implies "LIMIT 1".
+**
+**     SRT_Set         The result must be a single column.  Store each
+**                     row of result as the key in table pDest->iSDParm.
+**                     Apply the affinity pDest->affSdst before storing
+**                     results.  Used to implement "IN (SELECT ...)".
+**
+**     SRT_EphemTab    Create an temporary table pDest->iSDParm and store
+**                     the result there. The cursor is left open after
+**                     returning.  This is like SRT_Table except that
+**                     this destination uses OP_OpenEphemeral to create
+**                     the table first.
+**
+**     SRT_Coroutine   Generate a co-routine that returns a new row of
+**                     results each time it is invoked.  The entry point
+**                     of the co-routine is stored in register pDest->iSDParm
+**                     and the result row is stored in pDest->nDest registers
+**                     starting with pDest->iSdst.
+**
+**     SRT_Table       Store results in temporary table pDest->iSDParm.
+**     SRT_Fifo        This is like SRT_EphemTab except that the table
+**                     is assumed to already be open.  SRT_Fifo has
+**                     the additional property of being able to ignore
+**                     the ORDER BY clause.
+**
+**     SRT_DistFifo    Store results in a temporary table pDest->iSDParm.
+**                     But also use temporary table pDest->iSDParm+1 as
+**                     a record of all prior results and ignore any duplicate
+**                     rows.  Name means:  "Distinct Fifo".
+**
+**     SRT_Queue       Store results in priority queue pDest->iSDParm (really
+**                     an index).  Append a sequence number so that all entries
+**                     are distinct.
+**
+**     SRT_DistQueue   Store results in priority queue pDest->iSDParm only if
+**                     the same record has never been stored before.  The
+**                     index at pDest->iSDParm+1 hold all prior stores.
+*/
+#define SRT_Union        1  /* Store result as keys in an index */
+#define SRT_Except       2  /* Remove result from a UNION index */
+#define SRT_Exists       3  /* Store 1 if the result is not empty */
+#define SRT_Discard      4  /* Do not save the results anywhere */
+#define SRT_Fifo         5  /* Store result as data with an automatic rowid */
+#define SRT_DistFifo     6  /* Like SRT_Fifo, but unique results only */
+#define SRT_Queue        7  /* Store result in an queue */
+#define SRT_DistQueue    8  /* Like SRT_Queue, but unique results only */
+
+/* The ORDER BY clause is ignored for all of the above */
+#define IgnorableOrderby(X) ((X->eDest)<=SRT_DistQueue)
+
+#define SRT_Output       9  /* Output each row of result */
+#define SRT_Mem         10  /* Store result in a memory cell */
+#define SRT_Set         11  /* Store results as keys in an index */
+#define SRT_EphemTab    12  /* Create transient tab and store like SRT_Table */
+#define SRT_Coroutine   13  /* Generate a single row of result */
+#define SRT_Table       14  /* Store result as data with an automatic rowid */
+
+/*
+** An instance of this object describes where to put of the results of
+** a SELECT statement.
+*/
+struct SelectDest {
+  u8 eDest;            /* How to dispose of the results.  On of SRT_* above. */
+  char *zAffSdst;      /* Affinity used when eDest==SRT_Set */
+  int iSDParm;         /* A parameter used by the eDest disposal method */
+  int iSdst;           /* Base register where results are written */
+  int nSdst;           /* Number of registers allocated */
+  ExprList *pOrderBy;  /* Key columns for SRT_Queue and SRT_DistQueue */
+};
+
+/*
+** During code generation of statements that do inserts into AUTOINCREMENT
+** tables, the following information is attached to the Table.u.autoInc.p
+** pointer of each autoincrement table to record some side information that
+** the code generator needs.  We have to keep per-table autoincrement
+** information in case inserts are done within triggers.  Triggers do not
+** normally coordinate their activities, but we do need to coordinate the
+** loading and saving of autoincrement information.
+*/
+struct AutoincInfo {
+  AutoincInfo *pNext;   /* Next info block in a list of them all */
+  Table *pTab;          /* Table this info block refers to */
+  int iDb;              /* Index in sqlite3.aDb[] of database holding pTab */
+  int regCtr;           /* Memory register holding the rowid counter */
+};
+
+/*
+** Size of the column cache
+*/
+#ifndef SQLITE_N_COLCACHE
+# define SQLITE_N_COLCACHE 10
+#endif
+
+/*
+** At least one instance of the following structure is created for each
+** trigger that may be fired while parsing an INSERT, UPDATE or DELETE
+** statement. All such objects are stored in the linked list headed at
+** Parse.pTriggerPrg and deleted once statement compilation has been
+** completed.
+**
+** A Vdbe sub-program that implements the body and WHEN clause of trigger
+** TriggerPrg.pTrigger, assuming a default ON CONFLICT clause of
+** TriggerPrg.orconf, is stored in the TriggerPrg.pProgram variable.
+** The Parse.pTriggerPrg list never contains two entries with the same
+** values for both pTrigger and orconf.
+**
+** The TriggerPrg.aColmask[0] variable is set to a mask of old.* columns
+** accessed (or set to 0 for triggers fired as a result of INSERT
+** statements). Similarly, the TriggerPrg.aColmask[1] variable is set to
+** a mask of new.* columns used by the program.
+*/
+struct TriggerPrg {
+  Trigger *pTrigger;      /* Trigger this program was coded from */
+  TriggerPrg *pNext;      /* Next entry in Parse.pTriggerPrg list */
+  SubProgram *pProgram;   /* Program implementing pTrigger/orconf */
+  int orconf;             /* Default ON CONFLICT policy */
+  u32 aColmask[2];        /* Masks of old.*, new.* columns accessed */
+};
+
+/*
+** The yDbMask datatype for the bitmask of all attached databases.
+*/
+#if SQLITE_MAX_ATTACHED>30
+  typedef unsigned char yDbMask[(SQLITE_MAX_ATTACHED+9)/8];
+# define DbMaskTest(M,I)    (((M)[(I)/8]&(1<<((I)&7)))!=0)
+# define DbMaskZero(M)      memset((M),0,sizeof(M))
+# define DbMaskSet(M,I)     (M)[(I)/8]|=(1<<((I)&7))
+# define DbMaskAllZero(M)   sqlite3DbMaskAllZero(M)
+# define DbMaskNonZero(M)   (sqlite3DbMaskAllZero(M)==0)
+#else
+  typedef unsigned int yDbMask;
+# define DbMaskTest(M,I)    (((M)&(((yDbMask)1)<<(I)))!=0)
+# define DbMaskZero(M)      (M)=0
+# define DbMaskSet(M,I)     (M)|=(((yDbMask)1)<<(I))
+# define DbMaskAllZero(M)   (M)==0
+# define DbMaskNonZero(M)   (M)!=0
+#endif
+
+/*
+** An SQL parser context.  A copy of this structure is passed through
+** the parser and down into all the parser action routine in order to
+** carry around information that is global to the entire parse.
+**
+** The structure is divided into two parts.  When the parser and code
+** generate call themselves recursively, the first part of the structure
+** is constant but the second part is reset at the beginning and end of
+** each recursion.
+**
+** The nTableLock and aTableLock variables are only used if the shared-cache
+** feature is enabled (if sqlite3Tsd()->useSharedData is true). They are
+** used to store the set of table-locks required by the statement being
+** compiled. Function sqlite3TableLock() is used to add entries to the
+** list.
+*/
+struct Parse {
+  sqlite3 *db;         /* The main database structure */
+  char *zErrMsg;       /* An error message */
+  Vdbe *pVdbe;         /* An engine for executing database bytecode */
+  int rc;              /* Return code from execution */
+  u8 colNamesSet;      /* TRUE after OP_ColumnName has been issued to pVdbe */
+  u8 checkSchema;      /* Causes schema cookie check after an error */
+  u8 nested;           /* Number of nested calls to the parser/code generator */
+  u8 nTempReg;         /* Number of temporary registers in aTempReg[] */
+  u8 isMultiWrite;     /* True if statement may modify/insert multiple rows */
+  u8 mayAbort;         /* True if statement may throw an ABORT exception */
+  u8 hasCompound;      /* Need to invoke convertCompoundSelectToSubquery() */
+  u8 okConstFactor;    /* OK to factor out constants */
+  u8 disableLookaside; /* Number of times lookaside has been disabled */
+  u8 nColCache;        /* Number of entries in aColCache[] */
+  int nRangeReg;       /* Size of the temporary register block */
+  int iRangeReg;       /* First register in temporary register block */
+  int nErr;            /* Number of errors seen */
+  int nTab;            /* Number of previously allocated VDBE cursors */
+  int nMem;            /* Number of memory cells used so far */
+  int nOpAlloc;        /* Number of slots allocated for Vdbe.aOp[] */
+  int szOpAlloc;       /* Bytes of memory space allocated for Vdbe.aOp[] */
+  int ckBase;          /* Base register of data during check constraints */
+  int iSelfTab;        /* Table of an index whose exprs are being coded */
+  int iCacheLevel;     /* ColCache valid when aColCache[].iLevel<=iCacheLevel */
+  int iCacheCnt;       /* Counter used to generate aColCache[].lru values */
+  int nLabel;          /* Number of labels used */
+  int *aLabel;         /* Space to hold the labels */
+  ExprList *pConstExpr;/* Constant expressions */
+  Token constraintName;/* Name of the constraint currently being parsed */
+  yDbMask writeMask;   /* Start a write transaction on these databases */
+  yDbMask cookieMask;  /* Bitmask of schema verified databases */
+  int regRowid;        /* Register holding rowid of CREATE TABLE entry */
+  int regRoot;         /* Register holding root page number for new objects */
+  int nMaxArg;         /* Max args passed to user function by sub-program */
+#if SELECTTRACE_ENABLED
+  int nSelect;         /* Number of SELECT statements seen */
+  int nSelectIndent;   /* How far to indent SELECTTRACE() output */
+#endif
+#ifndef SQLITE_OMIT_SHARED_CACHE
+  int nTableLock;        /* Number of locks in aTableLock */
+  TableLock *aTableLock; /* Required table locks for shared-cache mode */
+#endif
+  AutoincInfo *pAinc;  /* Information about AUTOINCREMENT counters */
+  Parse *pToplevel;    /* Parse structure for main program (or NULL) */
+  Table *pTriggerTab;  /* Table triggers are being coded for */
+  int addrCrTab;       /* Address of OP_CreateTable opcode on CREATE TABLE */
+  u32 nQueryLoop;      /* Est number of iterations of a query (10*log2(N)) */
+  u32 oldmask;         /* Mask of old.* columns referenced */
+  u32 newmask;         /* Mask of new.* columns referenced */
+  u8 eTriggerOp;       /* TK_UPDATE, TK_INSERT or TK_DELETE */
+  u8 eOrconf;          /* Default ON CONFLICT policy for trigger steps */
+  u8 disableTriggers;  /* True to disable triggers */
+
+  /**************************************************************************
+  ** Fields above must be initialized to zero.  The fields that follow,
+  ** down to the beginning of the recursive section, do not need to be
+  ** initialized as they will be set before being used.  The boundary is
+  ** determined by offsetof(Parse,aColCache).
+  **************************************************************************/
+
+  struct yColCache {
+    int iTable;           /* Table cursor number */
+    i16 iColumn;          /* Table column number */
+    u8 tempReg;           /* iReg is a temp register that needs to be freed */
+    int iLevel;           /* Nesting level */
+    int iReg;             /* Reg with value of this column. 0 means none. */
+    int lru;              /* Least recently used entry has the smallest value */
+  } aColCache[SQLITE_N_COLCACHE];  /* One for each column cache entry */
+  int aTempReg[8];        /* Holding area for temporary registers */
+  Token sNameToken;       /* Token with unqualified schema object name */
+
+  /************************************************************************
+  ** Above is constant between recursions.  Below is reset before and after
+  ** each recursion.  The boundary between these two regions is determined
+  ** using offsetof(Parse,sLastToken) so the sLastToken field must be the
+  ** first field in the recursive region.
+  ************************************************************************/
+
+  Token sLastToken;       /* The last token parsed */
+  ynVar nVar;               /* Number of '?' variables seen in the SQL so far */
+  int nzVar;                /* Number of available slots in azVar[] */
+  u8 iPkSortOrder;          /* ASC or DESC for INTEGER PRIMARY KEY */
+  u8 explain;               /* True if the EXPLAIN flag is found on the query */
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  u8 declareVtab;           /* True if inside sqlite3_declare_vtab() */
+  int nVtabLock;            /* Number of virtual tables to lock */
+#endif
+  int nHeight;              /* Expression tree height of current sub-select */
+#ifndef SQLITE_OMIT_EXPLAIN
+  int iSelectId;            /* ID of current select for EXPLAIN output */
+  int iNextSelectId;        /* Next available select ID for EXPLAIN output */
+#endif
+  char **azVar;             /* Pointers to names of parameters */
+  Vdbe *pReprepare;         /* VM being reprepared (sqlite3Reprepare()) */
+  const char *zTail;        /* All SQL text past the last semicolon parsed */
+  Table *pNewTable;         /* A table being constructed by CREATE TABLE */
+  Trigger *pNewTrigger;     /* Trigger under construct by a CREATE TRIGGER */
+  const char *zAuthContext; /* The 6th parameter to db->xAuth callbacks */
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  Token sArg;               /* Complete text of a module argument */
+  Table **apVtabLock;       /* Pointer to virtual tables needing locking */
+#endif
+  Table *pZombieTab;        /* List of Table objects to delete after code gen */
+  TriggerPrg *pTriggerPrg;  /* Linked list of coded triggers */
+  With *pWith;              /* Current WITH clause, or NULL */
+  With *pWithToFree;        /* Free this WITH object at the end of the parse */
+};
+
+/*
+** Sizes and pointers of various parts of the Parse object.
+*/
+#define PARSE_HDR_SZ offsetof(Parse,aColCache) /* Recursive part w/o aColCache*/
+#define PARSE_RECURSE_SZ offsetof(Parse,sLastToken)    /* Recursive part */
+#define PARSE_TAIL_SZ (sizeof(Parse)-PARSE_RECURSE_SZ) /* Non-recursive part */
+#define PARSE_TAIL(X) (((char*)(X))+PARSE_RECURSE_SZ)  /* Pointer to tail */
+
+/*
+** Return true if currently inside an sqlite3_declare_vtab() call.
+*/
+#ifdef SQLITE_OMIT_VIRTUALTABLE
+  #define IN_DECLARE_VTAB 0
+#else
+  #define IN_DECLARE_VTAB (pParse->declareVtab)
+#endif
+
+/*
+** An instance of the following structure can be declared on a stack and used
+** to save the Parse.zAuthContext value so that it can be restored later.
+*/
+struct AuthContext {
+  const char *zAuthContext;   /* Put saved Parse.zAuthContext here */
+  Parse *pParse;              /* The Parse structure */
+};
+
+/*
+** Bitfield flags for P5 value in various opcodes.
+**
+** Value constraints (enforced via assert()):
+**    OPFLAG_LENGTHARG    == SQLITE_FUNC_LENGTH
+**    OPFLAG_TYPEOFARG    == SQLITE_FUNC_TYPEOF
+**    OPFLAG_BULKCSR      == BTREE_BULKLOAD
+**    OPFLAG_SEEKEQ       == BTREE_SEEK_EQ
+**    OPFLAG_FORDELETE    == BTREE_FORDELETE
+**    OPFLAG_SAVEPOSITION == BTREE_SAVEPOSITION
+**    OPFLAG_AUXDELETE    == BTREE_AUXDELETE
+*/
+#define OPFLAG_NCHANGE       0x01    /* OP_Insert: Set to update db->nChange */
+                                     /* Also used in P2 (not P5) of OP_Delete */
+#define OPFLAG_EPHEM         0x01    /* OP_Column: Ephemeral output is ok */
+#define OPFLAG_LASTROWID     0x02    /* Set to update db->lastRowid */
+#define OPFLAG_ISUPDATE      0x04    /* This OP_Insert is an sql UPDATE */
+#define OPFLAG_APPEND        0x08    /* This is likely to be an append */
+#define OPFLAG_USESEEKRESULT 0x10    /* Try to avoid a seek in BtreeInsert() */
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+#define OPFLAG_ISNOOP        0x40    /* OP_Delete does pre-update-hook only */
+#endif
+#define OPFLAG_LENGTHARG     0x40    /* OP_Column only used for length() */
+#define OPFLAG_TYPEOFARG     0x80    /* OP_Column only used for typeof() */
+#define OPFLAG_BULKCSR       0x01    /* OP_Open** used to open bulk cursor */
+#define OPFLAG_SEEKEQ        0x02    /* OP_Open** cursor uses EQ seek only */
+#define OPFLAG_FORDELETE     0x08    /* OP_Open should use BTREE_FORDELETE */
+#define OPFLAG_P2ISREG       0x10    /* P2 to OP_Open** is a register number */
+#define OPFLAG_PERMUTE       0x01    /* OP_Compare: use the permutation */
+#define OPFLAG_SAVEPOSITION  0x02    /* OP_Delete: keep cursor position */
+#define OPFLAG_AUXDELETE     0x04    /* OP_Delete: index in a DELETE op */
+
+/*
+ * Each trigger present in the database schema is stored as an instance of
+ * struct Trigger.
+ *
+ * Pointers to instances of struct Trigger are stored in two ways.
+ * 1. In the "trigHash" hash table (part of the sqlite3* that represents the
+ *    database). This allows Trigger structures to be retrieved by name.
+ * 2. All triggers associated with a single table form a linked list, using the
+ *    pNext member of struct Trigger. A pointer to the first element of the
+ *    linked list is stored as the "pTrigger" member of the associated
+ *    struct Table.
+ *
+ * The "step_list" member points to the first element of a linked list
+ * containing the SQL statements specified as the trigger program.
+ */
+struct Trigger {
+  char *zName;            /* The name of the trigger                        */
+  char *table;            /* The table or view to which the trigger applies */
+  u8 op;                  /* One of TK_DELETE, TK_UPDATE, TK_INSERT         */
+  u8 tr_tm;               /* One of TRIGGER_BEFORE, TRIGGER_AFTER */
+  Expr *pWhen;            /* The WHEN clause of the expression (may be NULL) */
+  IdList *pColumns;       /* If this is an UPDATE OF <column-list> trigger,
+                             the <column-list> is stored here */
+  Schema *pSchema;        /* Schema containing the trigger */
+  Schema *pTabSchema;     /* Schema containing the table */
+  TriggerStep *step_list; /* Link list of trigger program steps             */
+  Trigger *pNext;         /* Next trigger associated with the table */
+};
+
+/*
+** A trigger is either a BEFORE or an AFTER trigger.  The following constants
+** determine which.
+**
+** If there are multiple triggers, you might of some BEFORE and some AFTER.
+** In that cases, the constants below can be ORed together.
+*/
+#define TRIGGER_BEFORE  1
+#define TRIGGER_AFTER   2
+
+/*
+ * An instance of struct TriggerStep is used to store a single SQL statement
+ * that is a part of a trigger-program.
+ *
+ * Instances of struct TriggerStep are stored in a singly linked list (linked
+ * using the "pNext" member) referenced by the "step_list" member of the
+ * associated struct Trigger instance. The first element of the linked list is
+ * the first step of the trigger-program.
+ *
+ * The "op" member indicates whether this is a "DELETE", "INSERT", "UPDATE" or
+ * "SELECT" statement. The meanings of the other members is determined by the
+ * value of "op" as follows:
+ *
+ * (op == TK_INSERT)
+ * orconf    -> stores the ON CONFLICT algorithm
+ * pSelect   -> If this is an INSERT INTO ... SELECT ... statement, then
+ *              this stores a pointer to the SELECT statement. Otherwise NULL.
+ * zTarget   -> Dequoted name of the table to insert into.
+ * pExprList -> If this is an INSERT INTO ... VALUES ... statement, then
+ *              this stores values to be inserted. Otherwise NULL.
+ * pIdList   -> If this is an INSERT INTO ... (<column-names>) VALUES ...
+ *              statement, then this stores the column-names to be
+ *              inserted into.
+ *
+ * (op == TK_DELETE)
+ * zTarget   -> Dequoted name of the table to delete from.
+ * pWhere    -> The WHERE clause of the DELETE statement if one is specified.
+ *              Otherwise NULL.
+ *
+ * (op == TK_UPDATE)
+ * zTarget   -> Dequoted name of the table to update.
+ * pWhere    -> The WHERE clause of the UPDATE statement if one is specified.
+ *              Otherwise NULL.
+ * pExprList -> A list of the columns to update and the expressions to update
+ *              them to. See sqlite3Update() documentation of "pChanges"
+ *              argument.
+ *
+ */
+struct TriggerStep {
+  u8 op;               /* One of TK_DELETE, TK_UPDATE, TK_INSERT, TK_SELECT */
+  u8 orconf;           /* OE_Rollback etc. */
+  Trigger *pTrig;      /* The trigger that this step is a part of */
+  Select *pSelect;     /* SELECT statement or RHS of INSERT INTO SELECT ... */
+  char *zTarget;       /* Target table for DELETE, UPDATE, INSERT */
+  Expr *pWhere;        /* The WHERE clause for DELETE or UPDATE steps */
+  ExprList *pExprList; /* SET clause for UPDATE. */
+  IdList *pIdList;     /* Column names for INSERT */
+  TriggerStep *pNext;  /* Next in the link-list */
+  TriggerStep *pLast;  /* Last element in link-list. Valid for 1st elem only */
+};
+
+/*
+** The following structure contains information used by the sqliteFix...
+** routines as they walk the parse tree to make database references
+** explicit.
+*/
+typedef struct DbFixer DbFixer;
+struct DbFixer {
+  Parse *pParse;      /* The parsing context.  Error messages written here */
+  Schema *pSchema;    /* Fix items to this schema */
+  int bVarOnly;       /* Check for variable references only */
+  const char *zDb;    /* Make sure all objects are contained in this database */
+  const char *zType;  /* Type of the container - used for error messages */
+  const Token *pName; /* Name of the container - used for error messages */
+};
+
+/*
+** An objected used to accumulate the text of a string where we
+** do not necessarily know how big the string will be in the end.
+*/
+struct StrAccum {
+  sqlite3 *db;         /* Optional database for lookaside.  Can be NULL */
+  char *zBase;         /* A base allocation.  Not from malloc. */
+  char *zText;         /* The string collected so far */
+  u32  nChar;          /* Length of the string so far */
+  u32  nAlloc;         /* Amount of space allocated in zText */
+  u32  mxAlloc;        /* Maximum allowed allocation.  0 for no malloc usage */
+  u8   accError;       /* STRACCUM_NOMEM or STRACCUM_TOOBIG */
+  u8   printfFlags;    /* SQLITE_PRINTF flags below */
+};
+#define STRACCUM_NOMEM   1
+#define STRACCUM_TOOBIG  2
+#define SQLITE_PRINTF_INTERNAL 0x01  /* Internal-use-only converters allowed */
+#define SQLITE_PRINTF_SQLFUNC  0x02  /* SQL function arguments to VXPrintf */
+#define SQLITE_PRINTF_MALLOCED 0x04  /* True if xText is allocated space */
+
+#define isMalloced(X)  (((X)->printfFlags & SQLITE_PRINTF_MALLOCED)!=0)
+
+
+/*
+** A pointer to this structure is used to communicate information
+** from sqlite3Init and OP_ParseSchema into the sqlite3InitCallback.
+*/
+typedef struct {
+  sqlite3 *db;        /* The database being initialized */
+  char **pzErrMsg;    /* Error message stored here */
+  int iDb;            /* 0 for main database.  1 for TEMP, 2.. for ATTACHed */
+  int rc;             /* Result code stored here */
+} InitData;
+
+/*
+** Structure containing global configuration data for the SQLite library.
+**
+** This structure also contains some state information.
+*/
+struct Sqlite3Config {
+  int bMemstat;                     /* True to enable memory status */
+  int bCoreMutex;                   /* True to enable core mutexing */
+  int bFullMutex;                   /* True to enable full mutexing */
+  int bOpenUri;                     /* True to interpret filenames as URIs */
+  int bUseCis;                      /* Use covering indices for full-scans */
+  int mxStrlen;                     /* Maximum string length */
+  int neverCorrupt;                 /* Database is always well-formed */
+  int szLookaside;                  /* Default lookaside buffer size */
+  int nLookaside;                   /* Default lookaside buffer count */
+  int nStmtSpill;                   /* Stmt-journal spill-to-disk threshold */
+  sqlite3_mem_methods m;            /* Low-level memory allocation interface */
+  sqlite3_mutex_methods mutex;      /* Low-level mutex interface */
+  sqlite3_pcache_methods2 pcache2;  /* Low-level page-cache interface */
+  void *pHeap;                      /* Heap storage space */
+  int nHeap;                        /* Size of pHeap[] */
+  int mnReq, mxReq;                 /* Min and max heap requests sizes */
+  sqlite3_int64 szMmap;             /* mmap() space per open file */
+  sqlite3_int64 mxMmap;             /* Maximum value for szMmap */
+  void *pScratch;                   /* Scratch memory */
+  int szScratch;                    /* Size of each scratch buffer */
+  int nScratch;                     /* Number of scratch buffers */
+  void *pPage;                      /* Page cache memory */
+  int szPage;                       /* Size of each page in pPage[] */
+  int nPage;                        /* Number of pages in pPage[] */
+  int mxParserStack;                /* maximum depth of the parser stack */
+  int sharedCacheEnabled;           /* true if shared-cache mode enabled */
+  u32 szPma;                        /* Maximum Sorter PMA size */
+  /* The above might be initialized to non-zero.  The following need to always
+  ** initially be zero, however. */
+  int isInit;                       /* True after initialization has finished */
+  int inProgress;                   /* True while initialization in progress */
+  int isMutexInit;                  /* True after mutexes are initialized */
+  int isMallocInit;                 /* True after malloc is initialized */
+  int isPCacheInit;                 /* True after malloc is initialized */
+  int nRefInitMutex;                /* Number of users of pInitMutex */
+  sqlite3_mutex *pInitMutex;        /* Mutex used by sqlite3_initialize() */
+  void (*xLog)(void*,int,const char*); /* Function for logging */
+  void *pLogArg;                       /* First argument to xLog() */
+#ifdef SQLITE_ENABLE_SQLLOG
+  void(*xSqllog)(void*,sqlite3*,const char*, int);
+  void *pSqllogArg;
+#endif
+#ifdef SQLITE_VDBE_COVERAGE
+  /* The following callback (if not NULL) is invoked on every VDBE branch
+  ** operation.  Set the callback using SQLITE_TESTCTRL_VDBE_COVERAGE.
+  */
+  void (*xVdbeBranch)(void*,int iSrcLine,u8 eThis,u8 eMx);  /* Callback */
+  void *pVdbeBranchArg;                                     /* 1st argument */
+#endif
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+  int (*xTestCallback)(int);        /* Invoked by sqlite3FaultSim() */
+#endif
+  int bLocaltimeFault;              /* True to fail localtime() calls */
+  int iOnceResetThreshold;          /* When to reset OP_Once counters */
+};
+
+/*
+** This macro is used inside of assert() statements to indicate that
+** the assert is only valid on a well-formed database.  Instead of:
+**
+**     assert( X );
+**
+** One writes:
+**
+**     assert( X || CORRUPT_DB );
+**
+** CORRUPT_DB is true during normal operation.  CORRUPT_DB does not indicate
+** that the database is definitely corrupt, only that it might be corrupt.
+** For most test cases, CORRUPT_DB is set to false using a special
+** sqlite3_test_control().  This enables assert() statements to prove
+** things that are always true for well-formed databases.
+*/
+#define CORRUPT_DB  (sqlite3Config.neverCorrupt==0)
+
+/*
+** Context pointer passed down through the tree-walk.
+*/
+struct Walker {
+  Parse *pParse;                            /* Parser context.  */
+  int (*xExprCallback)(Walker*, Expr*);     /* Callback for expressions */
+  int (*xSelectCallback)(Walker*,Select*);  /* Callback for SELECTs */
+  void (*xSelectCallback2)(Walker*,Select*);/* Second callback for SELECTs */
+  int walkerDepth;                          /* Number of subqueries */
+  u8 eCode;                                 /* A small processing code */
+  union {                                   /* Extra data for callback */
+    NameContext *pNC;                          /* Naming context */
+    int n;                                     /* A counter */
+    int iCur;                                  /* A cursor number */
+    SrcList *pSrcList;                         /* FROM clause */
+    struct SrcCount *pSrcCount;                /* Counting column references */
+    struct CCurHint *pCCurHint;                /* Used by codeCursorHint() */
+    int *aiCol;                                /* array of column indexes */
+    struct IdxCover *pIdxCover;                /* Check for index coverage */
+  } u;
+};
+
+/* Forward declarations */
+SQLITE_PRIVATE int sqlite3WalkExpr(Walker*, Expr*);
+SQLITE_PRIVATE int sqlite3WalkExprList(Walker*, ExprList*);
+SQLITE_PRIVATE int sqlite3WalkSelect(Walker*, Select*);
+SQLITE_PRIVATE int sqlite3WalkSelectExpr(Walker*, Select*);
+SQLITE_PRIVATE int sqlite3WalkSelectFrom(Walker*, Select*);
+SQLITE_PRIVATE int sqlite3ExprWalkNoop(Walker*, Expr*);
+
+/*
+** Return code from the parse-tree walking primitives and their
+** callbacks.
+*/
+#define WRC_Continue    0   /* Continue down into children */
+#define WRC_Prune       1   /* Omit children but continue walking siblings */
+#define WRC_Abort       2   /* Abandon the tree walk */
+
+/*
+** An instance of this structure represents a set of one or more CTEs
+** (common table expressions) created by a single WITH clause.
+*/
+struct With {
+  int nCte;                       /* Number of CTEs in the WITH clause */
+  With *pOuter;                   /* Containing WITH clause, or NULL */
+  struct Cte {                    /* For each CTE in the WITH clause.... */
+    char *zName;                    /* Name of this CTE */
+    ExprList *pCols;                /* List of explicit column names, or NULL */
+    Select *pSelect;                /* The definition of this CTE */
+    const char *zCteErr;            /* Error message for circular references */
+  } a[1];
+};
+
+#ifdef SQLITE_DEBUG
+/*
+** An instance of the TreeView object is used for printing the content of
+** data structures on sqlite3DebugPrintf() using a tree-like view.
+*/
+struct TreeView {
+  int iLevel;             /* Which level of the tree we are on */
+  u8  bLine[100];         /* Draw vertical in column i if bLine[i] is true */
+};
+#endif /* SQLITE_DEBUG */
+
+/*
+** Assuming zIn points to the first byte of a UTF-8 character,
+** advance zIn to point to the first byte of the next UTF-8 character.
+*/
+#define SQLITE_SKIP_UTF8(zIn) {                        \
+  if( (*(zIn++))>=0xc0 ){                              \
+    while( (*zIn & 0xc0)==0x80 ){ zIn++; }             \
+  }                                                    \
+}
+
+/*
+** The SQLITE_*_BKPT macros are substitutes for the error codes with
+** the same name but without the _BKPT suffix.  These macros invoke
+** routines that report the line-number on which the error originated
+** using sqlite3_log().  The routines also provide a convenient place
+** to set a debugger breakpoint.
+*/
+SQLITE_PRIVATE int sqlite3CorruptError(int);
+SQLITE_PRIVATE int sqlite3MisuseError(int);
+SQLITE_PRIVATE int sqlite3CantopenError(int);
+#define SQLITE_CORRUPT_BKPT sqlite3CorruptError(__LINE__)
+#define SQLITE_MISUSE_BKPT sqlite3MisuseError(__LINE__)
+#define SQLITE_CANTOPEN_BKPT sqlite3CantopenError(__LINE__)
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE   int sqlite3NomemError(int);
+SQLITE_PRIVATE   int sqlite3IoerrnomemError(int);
+# define SQLITE_NOMEM_BKPT sqlite3NomemError(__LINE__)
+# define SQLITE_IOERR_NOMEM_BKPT sqlite3IoerrnomemError(__LINE__)
+#else
+# define SQLITE_NOMEM_BKPT SQLITE_NOMEM
+# define SQLITE_IOERR_NOMEM_BKPT SQLITE_IOERR_NOMEM
+#endif
+
+/*
+** FTS3 and FTS4 both require virtual table support
+*/
+#if defined(SQLITE_OMIT_VIRTUALTABLE)
+# undef SQLITE_ENABLE_FTS3
+# undef SQLITE_ENABLE_FTS4
+#endif
+
+/*
+** FTS4 is really an extension for FTS3.  It is enabled using the
+** SQLITE_ENABLE_FTS3 macro.  But to avoid confusion we also call
+** the SQLITE_ENABLE_FTS4 macro to serve as an alias for SQLITE_ENABLE_FTS3.
+*/
+#if defined(SQLITE_ENABLE_FTS4) && !defined(SQLITE_ENABLE_FTS3)
+# define SQLITE_ENABLE_FTS3 1
+#endif
+
+/*
+** The ctype.h header is needed for non-ASCII systems.  It is also
+** needed by FTS3 when FTS3 is included in the amalgamation.
+*/
+#if !defined(SQLITE_ASCII) || \
+    (defined(SQLITE_ENABLE_FTS3) && defined(SQLITE_AMALGAMATION))
+# include <ctype.h>
+#endif
+
+/*
+** The following macros mimic the standard library functions toupper(),
+** isspace(), isalnum(), isdigit() and isxdigit(), respectively. The
+** sqlite versions only work for ASCII characters, regardless of locale.
+*/
+#ifdef SQLITE_ASCII
+# define sqlite3Toupper(x)  ((x)&~(sqlite3CtypeMap[(unsigned char)(x)]&0x20))
+# define sqlite3Isspace(x)   (sqlite3CtypeMap[(unsigned char)(x)]&0x01)
+# define sqlite3Isalnum(x)   (sqlite3CtypeMap[(unsigned char)(x)]&0x06)
+# define sqlite3Isalpha(x)   (sqlite3CtypeMap[(unsigned char)(x)]&0x02)
+# define sqlite3Isdigit(x)   (sqlite3CtypeMap[(unsigned char)(x)]&0x04)
+# define sqlite3Isxdigit(x)  (sqlite3CtypeMap[(unsigned char)(x)]&0x08)
+# define sqlite3Tolower(x)   (sqlite3UpperToLower[(unsigned char)(x)])
+# define sqlite3Isquote(x)   (sqlite3CtypeMap[(unsigned char)(x)]&0x80)
+#else
+# define sqlite3Toupper(x)   toupper((unsigned char)(x))
+# define sqlite3Isspace(x)   isspace((unsigned char)(x))
+# define sqlite3Isalnum(x)   isalnum((unsigned char)(x))
+# define sqlite3Isalpha(x)   isalpha((unsigned char)(x))
+# define sqlite3Isdigit(x)   isdigit((unsigned char)(x))
+# define sqlite3Isxdigit(x)  isxdigit((unsigned char)(x))
+# define sqlite3Tolower(x)   tolower((unsigned char)(x))
+# define sqlite3Isquote(x)   ((x)=='"'||(x)=='\''||(x)=='['||(x)=='`')
+#endif
+#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
+SQLITE_PRIVATE int sqlite3IsIdChar(u8);
+#endif
+
+/*
+** Internal function prototypes
+*/
+SQLITE_PRIVATE int sqlite3StrICmp(const char*,const char*);
+SQLITE_PRIVATE int sqlite3Strlen30(const char*);
+SQLITE_PRIVATE char *sqlite3ColumnType(Column*,char*);
+#define sqlite3StrNICmp sqlite3_strnicmp
+
+SQLITE_PRIVATE int sqlite3MallocInit(void);
+SQLITE_PRIVATE void sqlite3MallocEnd(void);
+SQLITE_PRIVATE void *sqlite3Malloc(u64);
+SQLITE_PRIVATE void *sqlite3MallocZero(u64);
+SQLITE_PRIVATE void *sqlite3DbMallocZero(sqlite3*, u64);
+SQLITE_PRIVATE void *sqlite3DbMallocRaw(sqlite3*, u64);
+SQLITE_PRIVATE void *sqlite3DbMallocRawNN(sqlite3*, u64);
+SQLITE_PRIVATE char *sqlite3DbStrDup(sqlite3*,const char*);
+SQLITE_PRIVATE char *sqlite3DbStrNDup(sqlite3*,const char*, u64);
+SQLITE_PRIVATE void *sqlite3Realloc(void*, u64);
+SQLITE_PRIVATE void *sqlite3DbReallocOrFree(sqlite3 *, void *, u64);
+SQLITE_PRIVATE void *sqlite3DbRealloc(sqlite3 *, void *, u64);
+SQLITE_PRIVATE void sqlite3DbFree(sqlite3*, void*);
+SQLITE_PRIVATE int sqlite3MallocSize(void*);
+SQLITE_PRIVATE int sqlite3DbMallocSize(sqlite3*, void*);
+SQLITE_PRIVATE void *sqlite3ScratchMalloc(int);
+SQLITE_PRIVATE void sqlite3ScratchFree(void*);
+SQLITE_PRIVATE void *sqlite3PageMalloc(int);
+SQLITE_PRIVATE void sqlite3PageFree(void*);
+SQLITE_PRIVATE void sqlite3MemSetDefault(void);
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+SQLITE_PRIVATE void sqlite3BenignMallocHooks(void (*)(void), void (*)(void));
+#endif
+SQLITE_PRIVATE int sqlite3HeapNearlyFull(void);
+
+/*
+** On systems with ample stack space and that support alloca(), make
+** use of alloca() to obtain space for large automatic objects.  By default,
+** obtain space from malloc().
+**
+** The alloca() routine never returns NULL.  This will cause code paths
+** that deal with sqlite3StackAlloc() failures to be unreachable.
+*/
+#ifdef SQLITE_USE_ALLOCA
+# define sqlite3StackAllocRaw(D,N)   alloca(N)
+# define sqlite3StackAllocZero(D,N)  memset(alloca(N), 0, N)
+# define sqlite3StackFree(D,P)
+#else
+# define sqlite3StackAllocRaw(D,N)   sqlite3DbMallocRaw(D,N)
+# define sqlite3StackAllocZero(D,N)  sqlite3DbMallocZero(D,N)
+# define sqlite3StackFree(D,P)       sqlite3DbFree(D,P)
+#endif
+
+/* Do not allow both MEMSYS5 and MEMSYS3 to be defined together.  If they
+** are, disable MEMSYS3
+*/
+#ifdef SQLITE_ENABLE_MEMSYS5
+SQLITE_PRIVATE const sqlite3_mem_methods *sqlite3MemGetMemsys5(void);
+#undef SQLITE_ENABLE_MEMSYS3
+#endif
+#ifdef SQLITE_ENABLE_MEMSYS3
+SQLITE_PRIVATE const sqlite3_mem_methods *sqlite3MemGetMemsys3(void);
+#endif
+
+
+#ifndef SQLITE_MUTEX_OMIT
+SQLITE_PRIVATE   sqlite3_mutex_methods const *sqlite3DefaultMutex(void);
+SQLITE_PRIVATE   sqlite3_mutex_methods const *sqlite3NoopMutex(void);
+SQLITE_PRIVATE   sqlite3_mutex *sqlite3MutexAlloc(int);
+SQLITE_PRIVATE   int sqlite3MutexInit(void);
+SQLITE_PRIVATE   int sqlite3MutexEnd(void);
+#endif
+#if !defined(SQLITE_MUTEX_OMIT) && !defined(SQLITE_MUTEX_NOOP)
+SQLITE_PRIVATE   void sqlite3MemoryBarrier(void);
+#else
+# define sqlite3MemoryBarrier()
+#endif
+
+SQLITE_PRIVATE sqlite3_int64 sqlite3StatusValue(int);
+SQLITE_PRIVATE void sqlite3StatusUp(int, int);
+SQLITE_PRIVATE void sqlite3StatusDown(int, int);
+SQLITE_PRIVATE void sqlite3StatusHighwater(int, int);
+
+/* Access to mutexes used by sqlite3_status() */
+SQLITE_PRIVATE sqlite3_mutex *sqlite3Pcache1Mutex(void);
+SQLITE_PRIVATE sqlite3_mutex *sqlite3MallocMutex(void);
+
+#ifndef SQLITE_OMIT_FLOATING_POINT
+SQLITE_PRIVATE   int sqlite3IsNaN(double);
+#else
+# define sqlite3IsNaN(X)  0
+#endif
+
+/*
+** An instance of the following structure holds information about SQL
+** functions arguments that are the parameters to the printf() function.
+*/
+struct PrintfArguments {
+  int nArg;                /* Total number of arguments */
+  int nUsed;               /* Number of arguments used so far */
+  sqlite3_value **apArg;   /* The argument values */
+};
+
+SQLITE_PRIVATE void sqlite3VXPrintf(StrAccum*, const char*, va_list);
+SQLITE_PRIVATE void sqlite3XPrintf(StrAccum*, const char*, ...);
+SQLITE_PRIVATE char *sqlite3MPrintf(sqlite3*,const char*, ...);
+SQLITE_PRIVATE char *sqlite3VMPrintf(sqlite3*,const char*, va_list);
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
+SQLITE_PRIVATE   void sqlite3DebugPrintf(const char*, ...);
+#endif
+#if defined(SQLITE_TEST)
+SQLITE_PRIVATE   void *sqlite3TestTextToPtr(const char*);
+#endif
+
+#if defined(SQLITE_DEBUG)
+SQLITE_PRIVATE   void sqlite3TreeViewExpr(TreeView*, const Expr*, u8);
+SQLITE_PRIVATE   void sqlite3TreeViewBareExprList(TreeView*, const ExprList*, const char*);
+SQLITE_PRIVATE   void sqlite3TreeViewExprList(TreeView*, const ExprList*, u8, const char*);
+SQLITE_PRIVATE   void sqlite3TreeViewSelect(TreeView*, const Select*, u8);
+SQLITE_PRIVATE   void sqlite3TreeViewWith(TreeView*, const With*, u8);
+#endif
+
+
+SQLITE_PRIVATE void sqlite3SetString(char **, sqlite3*, const char*);
+SQLITE_PRIVATE void sqlite3ErrorMsg(Parse*, const char*, ...);
+SQLITE_PRIVATE void sqlite3Dequote(char*);
+SQLITE_PRIVATE void sqlite3TokenInit(Token*,char*);
+SQLITE_PRIVATE int sqlite3KeywordCode(const unsigned char*, int);
+SQLITE_PRIVATE int sqlite3RunParser(Parse*, const char*, char **);
+SQLITE_PRIVATE void sqlite3FinishCoding(Parse*);
+SQLITE_PRIVATE int sqlite3GetTempReg(Parse*);
+SQLITE_PRIVATE void sqlite3ReleaseTempReg(Parse*,int);
+SQLITE_PRIVATE int sqlite3GetTempRange(Parse*,int);
+SQLITE_PRIVATE void sqlite3ReleaseTempRange(Parse*,int,int);
+SQLITE_PRIVATE void sqlite3ClearTempRegCache(Parse*);
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE int sqlite3NoTempsInRange(Parse*,int,int);
+#endif
+SQLITE_PRIVATE Expr *sqlite3ExprAlloc(sqlite3*,int,const Token*,int);
+SQLITE_PRIVATE Expr *sqlite3Expr(sqlite3*,int,const char*);
+SQLITE_PRIVATE void sqlite3ExprAttachSubtrees(sqlite3*,Expr*,Expr*,Expr*);
+SQLITE_PRIVATE Expr *sqlite3PExpr(Parse*, int, Expr*, Expr*, const Token*);
+SQLITE_PRIVATE void sqlite3PExprAddSelect(Parse*, Expr*, Select*);
+SQLITE_PRIVATE Expr *sqlite3ExprAnd(sqlite3*,Expr*, Expr*);
+SQLITE_PRIVATE Expr *sqlite3ExprFunction(Parse*,ExprList*, Token*);
+SQLITE_PRIVATE void sqlite3ExprAssignVarNumber(Parse*, Expr*, u32);
+SQLITE_PRIVATE void sqlite3ExprDelete(sqlite3*, Expr*);
+SQLITE_PRIVATE ExprList *sqlite3ExprListAppend(Parse*,ExprList*,Expr*);
+SQLITE_PRIVATE ExprList *sqlite3ExprListAppendVector(Parse*,ExprList*,IdList*,Expr*);
+SQLITE_PRIVATE void sqlite3ExprListSetSortOrder(ExprList*,int);
+SQLITE_PRIVATE void sqlite3ExprListSetName(Parse*,ExprList*,Token*,int);
+SQLITE_PRIVATE void sqlite3ExprListSetSpan(Parse*,ExprList*,ExprSpan*);
+SQLITE_PRIVATE void sqlite3ExprListDelete(sqlite3*, ExprList*);
+SQLITE_PRIVATE u32 sqlite3ExprListFlags(const ExprList*);
+SQLITE_PRIVATE int sqlite3Init(sqlite3*, char**);
+SQLITE_PRIVATE int sqlite3InitCallback(void*, int, char**, char**);
+SQLITE_PRIVATE void sqlite3Pragma(Parse*,Token*,Token*,Token*,int);
+SQLITE_PRIVATE void sqlite3ResetAllSchemasOfConnection(sqlite3*);
+SQLITE_PRIVATE void sqlite3ResetOneSchema(sqlite3*,int);
+SQLITE_PRIVATE void sqlite3CollapseDatabaseArray(sqlite3*);
+SQLITE_PRIVATE void sqlite3CommitInternalChanges(sqlite3*);
+SQLITE_PRIVATE void sqlite3DeleteColumnNames(sqlite3*,Table*);
+SQLITE_PRIVATE int sqlite3ColumnsFromExprList(Parse*,ExprList*,i16*,Column**);
+SQLITE_PRIVATE void sqlite3SelectAddColumnTypeAndCollation(Parse*,Table*,Select*);
+SQLITE_PRIVATE Table *sqlite3ResultSetOfSelect(Parse*,Select*);
+SQLITE_PRIVATE void sqlite3OpenMasterTable(Parse *, int);
+SQLITE_PRIVATE Index *sqlite3PrimaryKeyIndex(Table*);
+SQLITE_PRIVATE i16 sqlite3ColumnOfIndex(Index*, i16);
+SQLITE_PRIVATE void sqlite3StartTable(Parse*,Token*,Token*,int,int,int,int);
+#if SQLITE_ENABLE_HIDDEN_COLUMNS
+SQLITE_PRIVATE   void sqlite3ColumnPropertiesFromName(Table*, Column*);
+#else
+# define sqlite3ColumnPropertiesFromName(T,C) /* no-op */
+#endif
+SQLITE_PRIVATE void sqlite3AddColumn(Parse*,Token*,Token*);
+SQLITE_PRIVATE void sqlite3AddNotNull(Parse*, int);
+SQLITE_PRIVATE void sqlite3AddPrimaryKey(Parse*, ExprList*, int, int, int);
+SQLITE_PRIVATE void sqlite3AddCheckConstraint(Parse*, Expr*);
+SQLITE_PRIVATE void sqlite3AddDefaultValue(Parse*,ExprSpan*);
+SQLITE_PRIVATE void sqlite3AddCollateType(Parse*, Token*);
+SQLITE_PRIVATE void sqlite3EndTable(Parse*,Token*,Token*,u8,Select*);
+SQLITE_PRIVATE int sqlite3ParseUri(const char*,const char*,unsigned int*,
+                    sqlite3_vfs**,char**,char **);
+SQLITE_PRIVATE Btree *sqlite3DbNameToBtree(sqlite3*,const char*);
+
+#ifdef SQLITE_OMIT_BUILTIN_TEST
+# define sqlite3FaultSim(X) SQLITE_OK
+#else
+SQLITE_PRIVATE   int sqlite3FaultSim(int);
+#endif
+
+SQLITE_PRIVATE Bitvec *sqlite3BitvecCreate(u32);
+SQLITE_PRIVATE int sqlite3BitvecTest(Bitvec*, u32);
+SQLITE_PRIVATE int sqlite3BitvecTestNotNull(Bitvec*, u32);
+SQLITE_PRIVATE int sqlite3BitvecSet(Bitvec*, u32);
+SQLITE_PRIVATE void sqlite3BitvecClear(Bitvec*, u32, void*);
+SQLITE_PRIVATE void sqlite3BitvecDestroy(Bitvec*);
+SQLITE_PRIVATE u32 sqlite3BitvecSize(Bitvec*);
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+SQLITE_PRIVATE int sqlite3BitvecBuiltinTest(int,int*);
+#endif
+
+SQLITE_PRIVATE RowSet *sqlite3RowSetInit(sqlite3*, void*, unsigned int);
+SQLITE_PRIVATE void sqlite3RowSetClear(RowSet*);
+SQLITE_PRIVATE void sqlite3RowSetInsert(RowSet*, i64);
+SQLITE_PRIVATE int sqlite3RowSetTest(RowSet*, int iBatch, i64);
+SQLITE_PRIVATE int sqlite3RowSetNext(RowSet*, i64*);
+
+SQLITE_PRIVATE void sqlite3CreateView(Parse*,Token*,Token*,Token*,ExprList*,Select*,int,int);
+
+#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_VIRTUALTABLE)
+SQLITE_PRIVATE   int sqlite3ViewGetColumnNames(Parse*,Table*);
+#else
+# define sqlite3ViewGetColumnNames(A,B) 0
+#endif
+
+#if SQLITE_MAX_ATTACHED>30
+SQLITE_PRIVATE   int sqlite3DbMaskAllZero(yDbMask);
+#endif
+SQLITE_PRIVATE void sqlite3DropTable(Parse*, SrcList*, int, int);
+SQLITE_PRIVATE void sqlite3CodeDropTable(Parse*, Table*, int, int);
+SQLITE_PRIVATE void sqlite3DeleteTable(sqlite3*, Table*);
+#ifndef SQLITE_OMIT_AUTOINCREMENT
+SQLITE_PRIVATE   void sqlite3AutoincrementBegin(Parse *pParse);
+SQLITE_PRIVATE   void sqlite3AutoincrementEnd(Parse *pParse);
+#else
+# define sqlite3AutoincrementBegin(X)
+# define sqlite3AutoincrementEnd(X)
+#endif
+SQLITE_PRIVATE void sqlite3Insert(Parse*, SrcList*, Select*, IdList*, int);
+SQLITE_PRIVATE void *sqlite3ArrayAllocate(sqlite3*,void*,int,int*,int*);
+SQLITE_PRIVATE IdList *sqlite3IdListAppend(sqlite3*, IdList*, Token*);
+SQLITE_PRIVATE int sqlite3IdListIndex(IdList*,const char*);
+SQLITE_PRIVATE SrcList *sqlite3SrcListEnlarge(sqlite3*, SrcList*, int, int);
+SQLITE_PRIVATE SrcList *sqlite3SrcListAppend(sqlite3*, SrcList*, Token*, Token*);
+SQLITE_PRIVATE SrcList *sqlite3SrcListAppendFromTerm(Parse*, SrcList*, Token*, Token*,
+                                      Token*, Select*, Expr*, IdList*);
+SQLITE_PRIVATE void sqlite3SrcListIndexedBy(Parse *, SrcList *, Token *);
+SQLITE_PRIVATE void sqlite3SrcListFuncArgs(Parse*, SrcList*, ExprList*);
+SQLITE_PRIVATE int sqlite3IndexedByLookup(Parse *, struct SrcList_item *);
+SQLITE_PRIVATE void sqlite3SrcListShiftJoinType(SrcList*);
+SQLITE_PRIVATE void sqlite3SrcListAssignCursors(Parse*, SrcList*);
+SQLITE_PRIVATE void sqlite3IdListDelete(sqlite3*, IdList*);
+SQLITE_PRIVATE void sqlite3SrcListDelete(sqlite3*, SrcList*);
+SQLITE_PRIVATE Index *sqlite3AllocateIndexObject(sqlite3*,i16,int,char**);
+SQLITE_PRIVATE void sqlite3CreateIndex(Parse*,Token*,Token*,SrcList*,ExprList*,int,Token*,
+                          Expr*, int, int, u8);
+SQLITE_PRIVATE void sqlite3DropIndex(Parse*, SrcList*, int);
+SQLITE_PRIVATE int sqlite3Select(Parse*, Select*, SelectDest*);
+SQLITE_PRIVATE Select *sqlite3SelectNew(Parse*,ExprList*,SrcList*,Expr*,ExprList*,
+                         Expr*,ExprList*,u32,Expr*,Expr*);
+SQLITE_PRIVATE void sqlite3SelectDelete(sqlite3*, Select*);
+SQLITE_PRIVATE Table *sqlite3SrcListLookup(Parse*, SrcList*);
+SQLITE_PRIVATE int sqlite3IsReadOnly(Parse*, Table*, int);
+SQLITE_PRIVATE void sqlite3OpenTable(Parse*, int iCur, int iDb, Table*, int);
+#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)
+SQLITE_PRIVATE Expr *sqlite3LimitWhere(Parse*,SrcList*,Expr*,ExprList*,Expr*,Expr*,char*);
+#endif
+SQLITE_PRIVATE void sqlite3DeleteFrom(Parse*, SrcList*, Expr*);
+SQLITE_PRIVATE void sqlite3Update(Parse*, SrcList*, ExprList*, Expr*, int);
+SQLITE_PRIVATE WhereInfo *sqlite3WhereBegin(Parse*,SrcList*,Expr*,ExprList*,ExprList*,u16,int);
+SQLITE_PRIVATE void sqlite3WhereEnd(WhereInfo*);
+SQLITE_PRIVATE LogEst sqlite3WhereOutputRowCount(WhereInfo*);
+SQLITE_PRIVATE int sqlite3WhereIsDistinct(WhereInfo*);
+SQLITE_PRIVATE int sqlite3WhereIsOrdered(WhereInfo*);
+SQLITE_PRIVATE int sqlite3WhereOrderedInnerLoop(WhereInfo*);
+SQLITE_PRIVATE int sqlite3WhereIsSorted(WhereInfo*);
+SQLITE_PRIVATE int sqlite3WhereContinueLabel(WhereInfo*);
+SQLITE_PRIVATE int sqlite3WhereBreakLabel(WhereInfo*);
+SQLITE_PRIVATE int sqlite3WhereOkOnePass(WhereInfo*, int*);
+#define ONEPASS_OFF      0        /* Use of ONEPASS not allowed */
+#define ONEPASS_SINGLE   1        /* ONEPASS valid for a single row update */
+#define ONEPASS_MULTI    2        /* ONEPASS is valid for multiple rows */
+SQLITE_PRIVATE void sqlite3ExprCodeLoadIndexColumn(Parse*, Index*, int, int, int);
+SQLITE_PRIVATE int sqlite3ExprCodeGetColumn(Parse*, Table*, int, int, int, u8);
+SQLITE_PRIVATE void sqlite3ExprCodeGetColumnToReg(Parse*, Table*, int, int, int);
+SQLITE_PRIVATE void sqlite3ExprCodeGetColumnOfTable(Vdbe*, Table*, int, int, int);
+SQLITE_PRIVATE void sqlite3ExprCodeMove(Parse*, int, int, int);
+SQLITE_PRIVATE void sqlite3ExprCacheStore(Parse*, int, int, int);
+SQLITE_PRIVATE void sqlite3ExprCachePush(Parse*);
+SQLITE_PRIVATE void sqlite3ExprCachePop(Parse*);
+SQLITE_PRIVATE void sqlite3ExprCacheRemove(Parse*, int, int);
+SQLITE_PRIVATE void sqlite3ExprCacheClear(Parse*);
+SQLITE_PRIVATE void sqlite3ExprCacheAffinityChange(Parse*, int, int);
+SQLITE_PRIVATE void sqlite3ExprCode(Parse*, Expr*, int);
+SQLITE_PRIVATE void sqlite3ExprCodeCopy(Parse*, Expr*, int);
+SQLITE_PRIVATE void sqlite3ExprCodeFactorable(Parse*, Expr*, int);
+SQLITE_PRIVATE void sqlite3ExprCodeAtInit(Parse*, Expr*, int, u8);
+SQLITE_PRIVATE int sqlite3ExprCodeTemp(Parse*, Expr*, int*);
+SQLITE_PRIVATE int sqlite3ExprCodeTarget(Parse*, Expr*, int);
+SQLITE_PRIVATE void sqlite3ExprCodeAndCache(Parse*, Expr*, int);
+SQLITE_PRIVATE int sqlite3ExprCodeExprList(Parse*, ExprList*, int, int, u8);
+#define SQLITE_ECEL_DUP      0x01  /* Deep, not shallow copies */
+#define SQLITE_ECEL_FACTOR   0x02  /* Factor out constant terms */
+#define SQLITE_ECEL_REF      0x04  /* Use ExprList.u.x.iOrderByCol */
+SQLITE_PRIVATE void sqlite3ExprIfTrue(Parse*, Expr*, int, int);
+SQLITE_PRIVATE void sqlite3ExprIfFalse(Parse*, Expr*, int, int);
+SQLITE_PRIVATE void sqlite3ExprIfFalseDup(Parse*, Expr*, int, int);
+SQLITE_PRIVATE Table *sqlite3FindTable(sqlite3*,const char*, const char*);
+#define LOCATE_VIEW    0x01
+#define LOCATE_NOERR   0x02
+SQLITE_PRIVATE Table *sqlite3LocateTable(Parse*,u32 flags,const char*, const char*);
+SQLITE_PRIVATE Table *sqlite3LocateTableItem(Parse*,u32 flags,struct SrcList_item *);
+SQLITE_PRIVATE Index *sqlite3FindIndex(sqlite3*,const char*, const char*);
+SQLITE_PRIVATE void sqlite3UnlinkAndDeleteTable(sqlite3*,int,const char*);
+SQLITE_PRIVATE void sqlite3UnlinkAndDeleteIndex(sqlite3*,int,const char*);
+SQLITE_PRIVATE void sqlite3Vacuum(Parse*,Token*);
+SQLITE_PRIVATE int sqlite3RunVacuum(char**, sqlite3*, int);
+SQLITE_PRIVATE char *sqlite3NameFromToken(sqlite3*, Token*);
+SQLITE_PRIVATE int sqlite3ExprCompare(Expr*, Expr*, int);
+SQLITE_PRIVATE int sqlite3ExprListCompare(ExprList*, ExprList*, int);
+SQLITE_PRIVATE int sqlite3ExprImpliesExpr(Expr*, Expr*, int);
+SQLITE_PRIVATE void sqlite3ExprAnalyzeAggregates(NameContext*, Expr*);
+SQLITE_PRIVATE void sqlite3ExprAnalyzeAggList(NameContext*,ExprList*);
+SQLITE_PRIVATE int sqlite3ExprCoveredByIndex(Expr*, int iCur, Index *pIdx);
+SQLITE_PRIVATE int sqlite3FunctionUsesThisSrc(Expr*, SrcList*);
+SQLITE_PRIVATE Vdbe *sqlite3GetVdbe(Parse*);
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+SQLITE_PRIVATE void sqlite3PrngSaveState(void);
+SQLITE_PRIVATE void sqlite3PrngRestoreState(void);
+#endif
+SQLITE_PRIVATE void sqlite3RollbackAll(sqlite3*,int);
+SQLITE_PRIVATE void sqlite3CodeVerifySchema(Parse*, int);
+SQLITE_PRIVATE void sqlite3CodeVerifyNamedSchema(Parse*, const char *zDb);
+SQLITE_PRIVATE void sqlite3BeginTransaction(Parse*, int);
+SQLITE_PRIVATE void sqlite3CommitTransaction(Parse*);
+SQLITE_PRIVATE void sqlite3RollbackTransaction(Parse*);
+SQLITE_PRIVATE void sqlite3Savepoint(Parse*, int, Token*);
+SQLITE_PRIVATE void sqlite3CloseSavepoints(sqlite3 *);
+SQLITE_PRIVATE void sqlite3LeaveMutexAndCloseZombie(sqlite3*);
+SQLITE_PRIVATE int sqlite3ExprIsConstant(Expr*);
+SQLITE_PRIVATE int sqlite3ExprIsConstantNotJoin(Expr*);
+SQLITE_PRIVATE int sqlite3ExprIsConstantOrFunction(Expr*, u8);
+SQLITE_PRIVATE int sqlite3ExprIsTableConstant(Expr*,int);
+#ifdef SQLITE_ENABLE_CURSOR_HINTS
+SQLITE_PRIVATE int sqlite3ExprContainsSubquery(Expr*);
+#endif
+SQLITE_PRIVATE int sqlite3ExprIsInteger(Expr*, int*);
+SQLITE_PRIVATE int sqlite3ExprCanBeNull(const Expr*);
+SQLITE_PRIVATE int sqlite3ExprNeedsNoAffinityChange(const Expr*, char);
+SQLITE_PRIVATE int sqlite3IsRowid(const char*);
+SQLITE_PRIVATE void sqlite3GenerateRowDelete(
+    Parse*,Table*,Trigger*,int,int,int,i16,u8,u8,u8,int);
+SQLITE_PRIVATE void sqlite3GenerateRowIndexDelete(Parse*, Table*, int, int, int*, int);
+SQLITE_PRIVATE int sqlite3GenerateIndexKey(Parse*, Index*, int, int, int, int*,Index*,int);
+SQLITE_PRIVATE void sqlite3ResolvePartIdxLabel(Parse*,int);
+SQLITE_PRIVATE void sqlite3GenerateConstraintChecks(Parse*,Table*,int*,int,int,int,int,
+                                     u8,u8,int,int*,int*);
+SQLITE_PRIVATE void sqlite3CompleteInsertion(Parse*,Table*,int,int,int,int*,int,int,int);
+SQLITE_PRIVATE int sqlite3OpenTableAndIndices(Parse*, Table*, int, u8, int, u8*, int*, int*);
+SQLITE_PRIVATE void sqlite3BeginWriteOperation(Parse*, int, int);
+SQLITE_PRIVATE void sqlite3MultiWrite(Parse*);
+SQLITE_PRIVATE void sqlite3MayAbort(Parse*);
+SQLITE_PRIVATE void sqlite3HaltConstraint(Parse*, int, int, char*, i8, u8);
+SQLITE_PRIVATE void sqlite3UniqueConstraint(Parse*, int, Index*);
+SQLITE_PRIVATE void sqlite3RowidConstraint(Parse*, int, Table*);
+SQLITE_PRIVATE Expr *sqlite3ExprDup(sqlite3*,Expr*,int);
+SQLITE_PRIVATE ExprList *sqlite3ExprListDup(sqlite3*,ExprList*,int);
+SQLITE_PRIVATE SrcList *sqlite3SrcListDup(sqlite3*,SrcList*,int);
+SQLITE_PRIVATE IdList *sqlite3IdListDup(sqlite3*,IdList*);
+SQLITE_PRIVATE Select *sqlite3SelectDup(sqlite3*,Select*,int);
+#if SELECTTRACE_ENABLED
+SQLITE_PRIVATE void sqlite3SelectSetName(Select*,const char*);
+#else
+# define sqlite3SelectSetName(A,B)
+#endif
+SQLITE_PRIVATE void sqlite3InsertBuiltinFuncs(FuncDef*,int);
+SQLITE_PRIVATE FuncDef *sqlite3FindFunction(sqlite3*,const char*,int,u8,u8);
+SQLITE_PRIVATE void sqlite3RegisterBuiltinFunctions(void);
+SQLITE_PRIVATE void sqlite3RegisterDateTimeFunctions(void);
+SQLITE_PRIVATE void sqlite3RegisterPerConnectionBuiltinFunctions(sqlite3*);
+SQLITE_PRIVATE int sqlite3SafetyCheckOk(sqlite3*);
+SQLITE_PRIVATE int sqlite3SafetyCheckSickOrOk(sqlite3*);
+SQLITE_PRIVATE void sqlite3ChangeCookie(Parse*, int);
+
+#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
+SQLITE_PRIVATE void sqlite3MaterializeView(Parse*, Table*, Expr*, int);
+#endif
+
+#ifndef SQLITE_OMIT_TRIGGER
+SQLITE_PRIVATE   void sqlite3BeginTrigger(Parse*, Token*,Token*,int,int,IdList*,SrcList*,
+                           Expr*,int, int);
+SQLITE_PRIVATE   void sqlite3FinishTrigger(Parse*, TriggerStep*, Token*);
+SQLITE_PRIVATE   void sqlite3DropTrigger(Parse*, SrcList*, int);
+SQLITE_PRIVATE   void sqlite3DropTriggerPtr(Parse*, Trigger*);
+SQLITE_PRIVATE   Trigger *sqlite3TriggersExist(Parse *, Table*, int, ExprList*, int *pMask);
+SQLITE_PRIVATE   Trigger *sqlite3TriggerList(Parse *, Table *);
+SQLITE_PRIVATE   void sqlite3CodeRowTrigger(Parse*, Trigger *, int, ExprList*, int, Table *,
+                            int, int, int);
+SQLITE_PRIVATE   void sqlite3CodeRowTriggerDirect(Parse *, Trigger *, Table *, int, int, int);
+  void sqliteViewTriggers(Parse*, Table*, Expr*, int, ExprList*);
+SQLITE_PRIVATE   void sqlite3DeleteTriggerStep(sqlite3*, TriggerStep*);
+SQLITE_PRIVATE   TriggerStep *sqlite3TriggerSelectStep(sqlite3*,Select*);
+SQLITE_PRIVATE   TriggerStep *sqlite3TriggerInsertStep(sqlite3*,Token*, IdList*,
+                                        Select*,u8);
+SQLITE_PRIVATE   TriggerStep *sqlite3TriggerUpdateStep(sqlite3*,Token*,ExprList*, Expr*, u8);
+SQLITE_PRIVATE   TriggerStep *sqlite3TriggerDeleteStep(sqlite3*,Token*, Expr*);
+SQLITE_PRIVATE   void sqlite3DeleteTrigger(sqlite3*, Trigger*);
+SQLITE_PRIVATE   void sqlite3UnlinkAndDeleteTrigger(sqlite3*,int,const char*);
+SQLITE_PRIVATE   u32 sqlite3TriggerColmask(Parse*,Trigger*,ExprList*,int,int,Table*,int);
+# define sqlite3ParseToplevel(p) ((p)->pToplevel ? (p)->pToplevel : (p))
+# define sqlite3IsToplevel(p) ((p)->pToplevel==0)
+#else
+# define sqlite3TriggersExist(B,C,D,E,F) 0
+# define sqlite3DeleteTrigger(A,B)
+# define sqlite3DropTriggerPtr(A,B)
+# define sqlite3UnlinkAndDeleteTrigger(A,B,C)
+# define sqlite3CodeRowTrigger(A,B,C,D,E,F,G,H,I)
+# define sqlite3CodeRowTriggerDirect(A,B,C,D,E,F)
+# define sqlite3TriggerList(X, Y) 0
+# define sqlite3ParseToplevel(p) p
+# define sqlite3IsToplevel(p) 1
+# define sqlite3TriggerColmask(A,B,C,D,E,F,G) 0
+#endif
+
+SQLITE_PRIVATE int sqlite3JoinType(Parse*, Token*, Token*, Token*);
+SQLITE_PRIVATE void sqlite3CreateForeignKey(Parse*, ExprList*, Token*, ExprList*, int);
+SQLITE_PRIVATE void sqlite3DeferForeignKey(Parse*, int);
+#ifndef SQLITE_OMIT_AUTHORIZATION
+SQLITE_PRIVATE   void sqlite3AuthRead(Parse*,Expr*,Schema*,SrcList*);
+SQLITE_PRIVATE   int sqlite3AuthCheck(Parse*,int, const char*, const char*, const char*);
+SQLITE_PRIVATE   void sqlite3AuthContextPush(Parse*, AuthContext*, const char*);
+SQLITE_PRIVATE   void sqlite3AuthContextPop(AuthContext*);
+SQLITE_PRIVATE   int sqlite3AuthReadCol(Parse*, const char *, const char *, int);
+#else
+# define sqlite3AuthRead(a,b,c,d)
+# define sqlite3AuthCheck(a,b,c,d,e)    SQLITE_OK
+# define sqlite3AuthContextPush(a,b,c)
+# define sqlite3AuthContextPop(a)  ((void)(a))
+#endif
+SQLITE_PRIVATE void sqlite3Attach(Parse*, Expr*, Expr*, Expr*);
+SQLITE_PRIVATE void sqlite3Detach(Parse*, Expr*);
+SQLITE_PRIVATE void sqlite3FixInit(DbFixer*, Parse*, int, const char*, const Token*);
+SQLITE_PRIVATE int sqlite3FixSrcList(DbFixer*, SrcList*);
+SQLITE_PRIVATE int sqlite3FixSelect(DbFixer*, Select*);
+SQLITE_PRIVATE int sqlite3FixExpr(DbFixer*, Expr*);
+SQLITE_PRIVATE int sqlite3FixExprList(DbFixer*, ExprList*);
+SQLITE_PRIVATE int sqlite3FixTriggerStep(DbFixer*, TriggerStep*);
+SQLITE_PRIVATE int sqlite3AtoF(const char *z, double*, int, u8);
+SQLITE_PRIVATE int sqlite3GetInt32(const char *, int*);
+SQLITE_PRIVATE int sqlite3Atoi(const char*);
+SQLITE_PRIVATE int sqlite3Utf16ByteLen(const void *pData, int nChar);
+SQLITE_PRIVATE int sqlite3Utf8CharLen(const char *pData, int nByte);
+SQLITE_PRIVATE u32 sqlite3Utf8Read(const u8**);
+SQLITE_PRIVATE LogEst sqlite3LogEst(u64);
+SQLITE_PRIVATE LogEst sqlite3LogEstAdd(LogEst,LogEst);
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+SQLITE_PRIVATE LogEst sqlite3LogEstFromDouble(double);
+#endif
+#if defined(SQLITE_ENABLE_STMT_SCANSTATUS) || \
+    defined(SQLITE_ENABLE_STAT3_OR_STAT4) || \
+    defined(SQLITE_EXPLAIN_ESTIMATED_ROWS)
+SQLITE_PRIVATE u64 sqlite3LogEstToInt(LogEst);
+#endif
+
+/*
+** Routines to read and write variable-length integers.  These used to
+** be defined locally, but now we use the varint routines in the util.c
+** file.
+*/
+SQLITE_PRIVATE int sqlite3PutVarint(unsigned char*, u64);
+SQLITE_PRIVATE u8 sqlite3GetVarint(const unsigned char *, u64 *);
+SQLITE_PRIVATE u8 sqlite3GetVarint32(const unsigned char *, u32 *);
+SQLITE_PRIVATE int sqlite3VarintLen(u64 v);
+
+/*
+** The common case is for a varint to be a single byte.  They following
+** macros handle the common case without a procedure call, but then call
+** the procedure for larger varints.
+*/
+#define getVarint32(A,B)  \
+  (u8)((*(A)<(u8)0x80)?((B)=(u32)*(A)),1:sqlite3GetVarint32((A),(u32 *)&(B)))
+#define putVarint32(A,B)  \
+  (u8)(((u32)(B)<(u32)0x80)?(*(A)=(unsigned char)(B)),1:\
+  sqlite3PutVarint((A),(B)))
+#define getVarint    sqlite3GetVarint
+#define putVarint    sqlite3PutVarint
+
+
+SQLITE_PRIVATE const char *sqlite3IndexAffinityStr(sqlite3*, Index*);
+SQLITE_PRIVATE void sqlite3TableAffinity(Vdbe*, Table*, int);
+SQLITE_PRIVATE char sqlite3CompareAffinity(Expr *pExpr, char aff2);
+SQLITE_PRIVATE int sqlite3IndexAffinityOk(Expr *pExpr, char idx_affinity);
+SQLITE_PRIVATE char sqlite3TableColumnAffinity(Table*,int);
+SQLITE_PRIVATE char sqlite3ExprAffinity(Expr *pExpr);
+SQLITE_PRIVATE int sqlite3Atoi64(const char*, i64*, int, u8);
+SQLITE_PRIVATE int sqlite3DecOrHexToI64(const char*, i64*);
+SQLITE_PRIVATE void sqlite3ErrorWithMsg(sqlite3*, int, const char*,...);
+SQLITE_PRIVATE void sqlite3Error(sqlite3*,int);
+SQLITE_PRIVATE void sqlite3SystemError(sqlite3*,int);
+SQLITE_PRIVATE void *sqlite3HexToBlob(sqlite3*, const char *z, int n);
+SQLITE_PRIVATE u8 sqlite3HexToInt(int h);
+SQLITE_PRIVATE int sqlite3TwoPartName(Parse *, Token *, Token *, Token **);
+
+#if defined(SQLITE_NEED_ERR_NAME)
+SQLITE_PRIVATE const char *sqlite3ErrName(int);
+#endif
+
+SQLITE_PRIVATE const char *sqlite3ErrStr(int);
+SQLITE_PRIVATE int sqlite3ReadSchema(Parse *pParse);
+SQLITE_PRIVATE CollSeq *sqlite3FindCollSeq(sqlite3*,u8 enc, const char*,int);
+SQLITE_PRIVATE CollSeq *sqlite3LocateCollSeq(Parse *pParse, const char*zName);
+SQLITE_PRIVATE CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr);
+SQLITE_PRIVATE Expr *sqlite3ExprAddCollateToken(Parse *pParse, Expr*, const Token*, int);
+SQLITE_PRIVATE Expr *sqlite3ExprAddCollateString(Parse*,Expr*,const char*);
+SQLITE_PRIVATE Expr *sqlite3ExprSkipCollate(Expr*);
+SQLITE_PRIVATE int sqlite3CheckCollSeq(Parse *, CollSeq *);
+SQLITE_PRIVATE int sqlite3CheckObjectName(Parse *, const char *);
+SQLITE_PRIVATE void sqlite3VdbeSetChanges(sqlite3 *, int);
+SQLITE_PRIVATE int sqlite3AddInt64(i64*,i64);
+SQLITE_PRIVATE int sqlite3SubInt64(i64*,i64);
+SQLITE_PRIVATE int sqlite3MulInt64(i64*,i64);
+SQLITE_PRIVATE int sqlite3AbsInt32(int);
+#ifdef SQLITE_ENABLE_8_3_NAMES
+SQLITE_PRIVATE void sqlite3FileSuffix3(const char*, char*);
+#else
+# define sqlite3FileSuffix3(X,Y)
+#endif
+SQLITE_PRIVATE u8 sqlite3GetBoolean(const char *z,u8);
+
+SQLITE_PRIVATE const void *sqlite3ValueText(sqlite3_value*, u8);
+SQLITE_PRIVATE int sqlite3ValueBytes(sqlite3_value*, u8);
+SQLITE_PRIVATE void sqlite3ValueSetStr(sqlite3_value*, int, const void *,u8,
+                        void(*)(void*));
+SQLITE_PRIVATE void sqlite3ValueSetNull(sqlite3_value*);
+SQLITE_PRIVATE void sqlite3ValueFree(sqlite3_value*);
+SQLITE_PRIVATE sqlite3_value *sqlite3ValueNew(sqlite3 *);
+SQLITE_PRIVATE char *sqlite3Utf16to8(sqlite3 *, const void*, int, u8);
+SQLITE_PRIVATE int sqlite3ValueFromExpr(sqlite3 *, Expr *, u8, u8, sqlite3_value **);
+SQLITE_PRIVATE void sqlite3ValueApplyAffinity(sqlite3_value *, u8, u8);
+#ifndef SQLITE_AMALGAMATION
+SQLITE_PRIVATE const unsigned char sqlite3OpcodeProperty[];
+SQLITE_PRIVATE const char sqlite3StrBINARY[];
+SQLITE_PRIVATE const unsigned char sqlite3UpperToLower[];
+SQLITE_PRIVATE const unsigned char sqlite3CtypeMap[];
+SQLITE_PRIVATE const Token sqlite3IntTokens[];
+SQLITE_PRIVATE SQLITE_WSD struct Sqlite3Config sqlite3Config;
+SQLITE_PRIVATE FuncDefHash sqlite3BuiltinFunctions;
+#ifndef SQLITE_OMIT_WSD
+SQLITE_PRIVATE int sqlite3PendingByte;
+#endif
+#endif
+SQLITE_PRIVATE void sqlite3RootPageMoved(sqlite3*, int, int, int);
+SQLITE_PRIVATE void sqlite3Reindex(Parse*, Token*, Token*);
+SQLITE_PRIVATE void sqlite3AlterFunctions(void);
+SQLITE_PRIVATE void sqlite3AlterRenameTable(Parse*, SrcList*, Token*);
+SQLITE_PRIVATE int sqlite3GetToken(const unsigned char *, int *);
+SQLITE_PRIVATE void sqlite3NestedParse(Parse*, const char*, ...);
+SQLITE_PRIVATE void sqlite3ExpirePreparedStatements(sqlite3*);
+SQLITE_PRIVATE int sqlite3CodeSubselect(Parse*, Expr *, int, int);
+SQLITE_PRIVATE void sqlite3SelectPrep(Parse*, Select*, NameContext*);
+SQLITE_PRIVATE void sqlite3SelectWrongNumTermsError(Parse *pParse, Select *p);
+SQLITE_PRIVATE int sqlite3MatchSpanName(const char*, const char*, const char*, const char*);
+SQLITE_PRIVATE int sqlite3ResolveExprNames(NameContext*, Expr*);
+SQLITE_PRIVATE int sqlite3ResolveExprListNames(NameContext*, ExprList*);
+SQLITE_PRIVATE void sqlite3ResolveSelectNames(Parse*, Select*, NameContext*);
+SQLITE_PRIVATE void sqlite3ResolveSelfReference(Parse*,Table*,int,Expr*,ExprList*);
+SQLITE_PRIVATE int sqlite3ResolveOrderGroupBy(Parse*, Select*, ExprList*, const char*);
+SQLITE_PRIVATE void sqlite3ColumnDefault(Vdbe *, Table *, int, int);
+SQLITE_PRIVATE void sqlite3AlterFinishAddColumn(Parse *, Token *);
+SQLITE_PRIVATE void sqlite3AlterBeginAddColumn(Parse *, SrcList *);
+SQLITE_PRIVATE CollSeq *sqlite3GetCollSeq(Parse*, u8, CollSeq *, const char*);
+SQLITE_PRIVATE char sqlite3AffinityType(const char*, u8*);
+SQLITE_PRIVATE void sqlite3Analyze(Parse*, Token*, Token*);
+SQLITE_PRIVATE int sqlite3InvokeBusyHandler(BusyHandler*);
+SQLITE_PRIVATE int sqlite3FindDb(sqlite3*, Token*);
+SQLITE_PRIVATE int sqlite3FindDbName(sqlite3 *, const char *);
+SQLITE_PRIVATE int sqlite3AnalysisLoad(sqlite3*,int iDB);
+SQLITE_PRIVATE void sqlite3DeleteIndexSamples(sqlite3*,Index*);
+SQLITE_PRIVATE void sqlite3DefaultRowEst(Index*);
+SQLITE_PRIVATE void sqlite3RegisterLikeFunctions(sqlite3*, int);
+SQLITE_PRIVATE int sqlite3IsLikeFunction(sqlite3*,Expr*,int*,char*);
+SQLITE_PRIVATE void sqlite3SchemaClear(void *);
+SQLITE_PRIVATE Schema *sqlite3SchemaGet(sqlite3 *, Btree *);
+SQLITE_PRIVATE int sqlite3SchemaToIndex(sqlite3 *db, Schema *);
+SQLITE_PRIVATE KeyInfo *sqlite3KeyInfoAlloc(sqlite3*,int,int);
+SQLITE_PRIVATE void sqlite3KeyInfoUnref(KeyInfo*);
+SQLITE_PRIVATE KeyInfo *sqlite3KeyInfoRef(KeyInfo*);
+SQLITE_PRIVATE KeyInfo *sqlite3KeyInfoOfIndex(Parse*, Index*);
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE int sqlite3KeyInfoIsWriteable(KeyInfo*);
+#endif
+SQLITE_PRIVATE int sqlite3CreateFunc(sqlite3 *, const char *, int, int, void *,
+  void (*)(sqlite3_context*,int,sqlite3_value **),
+  void (*)(sqlite3_context*,int,sqlite3_value **), void (*)(sqlite3_context*),
+  FuncDestructor *pDestructor
+);
+SQLITE_PRIVATE void sqlite3OomFault(sqlite3*);
+SQLITE_PRIVATE void sqlite3OomClear(sqlite3*);
+SQLITE_PRIVATE int sqlite3ApiExit(sqlite3 *db, int);
+SQLITE_PRIVATE int sqlite3OpenTempDatabase(Parse *);
+
+SQLITE_PRIVATE void sqlite3StrAccumInit(StrAccum*, sqlite3*, char*, int, int);
+SQLITE_PRIVATE void sqlite3StrAccumAppend(StrAccum*,const char*,int);
+SQLITE_PRIVATE void sqlite3StrAccumAppendAll(StrAccum*,const char*);
+SQLITE_PRIVATE void sqlite3AppendChar(StrAccum*,int,char);
+SQLITE_PRIVATE char *sqlite3StrAccumFinish(StrAccum*);
+SQLITE_PRIVATE void sqlite3StrAccumReset(StrAccum*);
+SQLITE_PRIVATE void sqlite3SelectDestInit(SelectDest*,int,int);
+SQLITE_PRIVATE Expr *sqlite3CreateColumnExpr(sqlite3 *, SrcList *, int, int);
+
+SQLITE_PRIVATE void sqlite3BackupRestart(sqlite3_backup *);
+SQLITE_PRIVATE void sqlite3BackupUpdate(sqlite3_backup *, Pgno, const u8 *);
+
+#ifndef SQLITE_OMIT_SUBQUERY
+SQLITE_PRIVATE int sqlite3ExprCheckIN(Parse*, Expr*);
+#else
+# define sqlite3ExprCheckIN(x,y) SQLITE_OK
+#endif
+
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+SQLITE_PRIVATE void sqlite3AnalyzeFunctions(void);
+SQLITE_PRIVATE int sqlite3Stat4ProbeSetValue(
+    Parse*,Index*,UnpackedRecord**,Expr*,int,int,int*);
+SQLITE_PRIVATE int sqlite3Stat4ValueFromExpr(Parse*, Expr*, u8, sqlite3_value**);
+SQLITE_PRIVATE void sqlite3Stat4ProbeFree(UnpackedRecord*);
+SQLITE_PRIVATE int sqlite3Stat4Column(sqlite3*, const void*, int, int, sqlite3_value**);
+SQLITE_PRIVATE char sqlite3IndexColumnAffinity(sqlite3*, Index*, int);
+#endif
+
+/*
+** The interface to the LEMON-generated parser
+*/
+SQLITE_PRIVATE void *sqlite3ParserAlloc(void*(*)(u64));
+SQLITE_PRIVATE void sqlite3ParserFree(void*, void(*)(void*));
+SQLITE_PRIVATE void sqlite3Parser(void*, int, Token, Parse*);
+#ifdef YYTRACKMAXSTACKDEPTH
+SQLITE_PRIVATE   int sqlite3ParserStackPeak(void*);
+#endif
+
+SQLITE_PRIVATE void sqlite3AutoLoadExtensions(sqlite3*);
+#ifndef SQLITE_OMIT_LOAD_EXTENSION
+SQLITE_PRIVATE   void sqlite3CloseExtensions(sqlite3*);
+#else
+# define sqlite3CloseExtensions(X)
+#endif
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+SQLITE_PRIVATE   void sqlite3TableLock(Parse *, int, int, u8, const char *);
+#else
+  #define sqlite3TableLock(v,w,x,y,z)
+#endif
+
+#ifdef SQLITE_TEST
+SQLITE_PRIVATE   int sqlite3Utf8To8(unsigned char*);
+#endif
+
+#ifdef SQLITE_OMIT_VIRTUALTABLE
+#  define sqlite3VtabClear(Y)
+#  define sqlite3VtabSync(X,Y) SQLITE_OK
+#  define sqlite3VtabRollback(X)
+#  define sqlite3VtabCommit(X)
+#  define sqlite3VtabInSync(db) 0
+#  define sqlite3VtabLock(X)
+#  define sqlite3VtabUnlock(X)
+#  define sqlite3VtabUnlockList(X)
+#  define sqlite3VtabSavepoint(X, Y, Z) SQLITE_OK
+#  define sqlite3GetVTable(X,Y)  ((VTable*)0)
+#else
+SQLITE_PRIVATE    void sqlite3VtabClear(sqlite3 *db, Table*);
+SQLITE_PRIVATE    void sqlite3VtabDisconnect(sqlite3 *db, Table *p);
+SQLITE_PRIVATE    int sqlite3VtabSync(sqlite3 *db, Vdbe*);
+SQLITE_PRIVATE    int sqlite3VtabRollback(sqlite3 *db);
+SQLITE_PRIVATE    int sqlite3VtabCommit(sqlite3 *db);
+SQLITE_PRIVATE    void sqlite3VtabLock(VTable *);
+SQLITE_PRIVATE    void sqlite3VtabUnlock(VTable *);
+SQLITE_PRIVATE    void sqlite3VtabUnlockList(sqlite3*);
+SQLITE_PRIVATE    int sqlite3VtabSavepoint(sqlite3 *, int, int);
+SQLITE_PRIVATE    void sqlite3VtabImportErrmsg(Vdbe*, sqlite3_vtab*);
+SQLITE_PRIVATE    VTable *sqlite3GetVTable(sqlite3*, Table*);
+#  define sqlite3VtabInSync(db) ((db)->nVTrans>0 && (db)->aVTrans==0)
+#endif
+SQLITE_PRIVATE int sqlite3VtabEponymousTableInit(Parse*,Module*);
+SQLITE_PRIVATE void sqlite3VtabEponymousTableClear(sqlite3*,Module*);
+SQLITE_PRIVATE void sqlite3VtabMakeWritable(Parse*,Table*);
+SQLITE_PRIVATE void sqlite3VtabBeginParse(Parse*, Token*, Token*, Token*, int);
+SQLITE_PRIVATE void sqlite3VtabFinishParse(Parse*, Token*);
+SQLITE_PRIVATE void sqlite3VtabArgInit(Parse*);
+SQLITE_PRIVATE void sqlite3VtabArgExtend(Parse*, Token*);
+SQLITE_PRIVATE int sqlite3VtabCallCreate(sqlite3*, int, const char *, char **);
+SQLITE_PRIVATE int sqlite3VtabCallConnect(Parse*, Table*);
+SQLITE_PRIVATE int sqlite3VtabCallDestroy(sqlite3*, int, const char *);
+SQLITE_PRIVATE int sqlite3VtabBegin(sqlite3 *, VTable *);
+SQLITE_PRIVATE FuncDef *sqlite3VtabOverloadFunction(sqlite3 *,FuncDef*, int nArg, Expr*);
+SQLITE_PRIVATE void sqlite3InvalidFunction(sqlite3_context*,int,sqlite3_value**);
+SQLITE_PRIVATE sqlite3_int64 sqlite3StmtCurrentTime(sqlite3_context*);
+SQLITE_PRIVATE int sqlite3VdbeParameterIndex(Vdbe*, const char*, int);
+SQLITE_PRIVATE int sqlite3TransferBindings(sqlite3_stmt *, sqlite3_stmt *);
+SQLITE_PRIVATE void sqlite3ParserReset(Parse*);
+SQLITE_PRIVATE int sqlite3Reprepare(Vdbe*);
+SQLITE_PRIVATE void sqlite3ExprListCheckLength(Parse*, ExprList*, const char*);
+SQLITE_PRIVATE CollSeq *sqlite3BinaryCompareCollSeq(Parse *, Expr *, Expr *);
+SQLITE_PRIVATE int sqlite3TempInMemory(const sqlite3*);
+SQLITE_PRIVATE const char *sqlite3JournalModename(int);
+#ifndef SQLITE_OMIT_WAL
+SQLITE_PRIVATE   int sqlite3Checkpoint(sqlite3*, int, int, int*, int*);
+SQLITE_PRIVATE   int sqlite3WalDefaultHook(void*,sqlite3*,const char*,int);
+#endif
+#ifndef SQLITE_OMIT_CTE
+SQLITE_PRIVATE   With *sqlite3WithAdd(Parse*,With*,Token*,ExprList*,Select*);
+SQLITE_PRIVATE   void sqlite3WithDelete(sqlite3*,With*);
+SQLITE_PRIVATE   void sqlite3WithPush(Parse*, With*, u8);
+#else
+#define sqlite3WithPush(x,y,z)
+#define sqlite3WithDelete(x,y)
+#endif
+
+/* Declarations for functions in fkey.c. All of these are replaced by
+** no-op macros if OMIT_FOREIGN_KEY is defined. In this case no foreign
+** key functionality is available. If OMIT_TRIGGER is defined but
+** OMIT_FOREIGN_KEY is not, only some of the functions are no-oped. In
+** this case foreign keys are parsed, but no other functionality is
+** provided (enforcement of FK constraints requires the triggers sub-system).
+*/
+#if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
+SQLITE_PRIVATE   void sqlite3FkCheck(Parse*, Table*, int, int, int*, int);
+SQLITE_PRIVATE   void sqlite3FkDropTable(Parse*, SrcList *, Table*);
+SQLITE_PRIVATE   void sqlite3FkActions(Parse*, Table*, ExprList*, int, int*, int);
+SQLITE_PRIVATE   int sqlite3FkRequired(Parse*, Table*, int*, int);
+SQLITE_PRIVATE   u32 sqlite3FkOldmask(Parse*, Table*);
+SQLITE_PRIVATE   FKey *sqlite3FkReferences(Table *);
+#else
+  #define sqlite3FkActions(a,b,c,d,e,f)
+  #define sqlite3FkCheck(a,b,c,d,e,f)
+  #define sqlite3FkDropTable(a,b,c)
+  #define sqlite3FkOldmask(a,b)         0
+  #define sqlite3FkRequired(a,b,c,d)    0
+#endif
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+SQLITE_PRIVATE   void sqlite3FkDelete(sqlite3 *, Table*);
+SQLITE_PRIVATE   int sqlite3FkLocateIndex(Parse*,Table*,FKey*,Index**,int**);
+#else
+  #define sqlite3FkDelete(a,b)
+  #define sqlite3FkLocateIndex(a,b,c,d,e)
+#endif
+
+
+/*
+** Available fault injectors.  Should be numbered beginning with 0.
+*/
+#define SQLITE_FAULTINJECTOR_MALLOC     0
+#define SQLITE_FAULTINJECTOR_COUNT      1
+
+/*
+** The interface to the code in fault.c used for identifying "benign"
+** malloc failures. This is only present if SQLITE_OMIT_BUILTIN_TEST
+** is not defined.
+*/
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+SQLITE_PRIVATE   void sqlite3BeginBenignMalloc(void);
+SQLITE_PRIVATE   void sqlite3EndBenignMalloc(void);
+#else
+  #define sqlite3BeginBenignMalloc()
+  #define sqlite3EndBenignMalloc()
+#endif
+
+/*
+** Allowed return values from sqlite3FindInIndex()
+*/
+#define IN_INDEX_ROWID        1   /* Search the rowid of the table */
+#define IN_INDEX_EPH          2   /* Search an ephemeral b-tree */
+#define IN_INDEX_INDEX_ASC    3   /* Existing index ASCENDING */
+#define IN_INDEX_INDEX_DESC   4   /* Existing index DESCENDING */
+#define IN_INDEX_NOOP         5   /* No table available. Use comparisons */
+/*
+** Allowed flags for the 3rd parameter to sqlite3FindInIndex().
+*/
+#define IN_INDEX_NOOP_OK     0x0001  /* OK to return IN_INDEX_NOOP */
+#define IN_INDEX_MEMBERSHIP  0x0002  /* IN operator used for membership test */
+#define IN_INDEX_LOOP        0x0004  /* IN operator used as a loop */
+SQLITE_PRIVATE int sqlite3FindInIndex(Parse *, Expr *, u32, int*, int*);
+
+SQLITE_PRIVATE int sqlite3JournalOpen(sqlite3_vfs *, const char *, sqlite3_file *, int, int);
+SQLITE_PRIVATE int sqlite3JournalSize(sqlite3_vfs *);
+#ifdef SQLITE_ENABLE_ATOMIC_WRITE
+SQLITE_PRIVATE   int sqlite3JournalCreate(sqlite3_file *);
+#endif
+
+SQLITE_PRIVATE int sqlite3JournalIsInMemory(sqlite3_file *p);
+SQLITE_PRIVATE void sqlite3MemJournalOpen(sqlite3_file *);
+
+SQLITE_PRIVATE void sqlite3ExprSetHeightAndFlags(Parse *pParse, Expr *p);
+#if SQLITE_MAX_EXPR_DEPTH>0
+SQLITE_PRIVATE   int sqlite3SelectExprHeight(Select *);
+SQLITE_PRIVATE   int sqlite3ExprCheckHeight(Parse*, int);
+#else
+  #define sqlite3SelectExprHeight(x) 0
+  #define sqlite3ExprCheckHeight(x,y)
+#endif
+
+SQLITE_PRIVATE u32 sqlite3Get4byte(const u8*);
+SQLITE_PRIVATE void sqlite3Put4byte(u8*, u32);
+
+#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
+SQLITE_PRIVATE   void sqlite3ConnectionBlocked(sqlite3 *, sqlite3 *);
+SQLITE_PRIVATE   void sqlite3ConnectionUnlocked(sqlite3 *db);
+SQLITE_PRIVATE   void sqlite3ConnectionClosed(sqlite3 *db);
+#else
+  #define sqlite3ConnectionBlocked(x,y)
+  #define sqlite3ConnectionUnlocked(x)
+  #define sqlite3ConnectionClosed(x)
+#endif
+
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE   void sqlite3ParserTrace(FILE*, char *);
+#endif
+
+/*
+** If the SQLITE_ENABLE IOTRACE exists then the global variable
+** sqlite3IoTrace is a pointer to a printf-like routine used to
+** print I/O tracing messages.
+*/
+#ifdef SQLITE_ENABLE_IOTRACE
+# define IOTRACE(A)  if( sqlite3IoTrace ){ sqlite3IoTrace A; }
+SQLITE_PRIVATE   void sqlite3VdbeIOTraceSql(Vdbe*);
+SQLITE_API SQLITE_EXTERN void (SQLITE_CDECL *sqlite3IoTrace)(const char*,...);
+#else
+# define IOTRACE(A)
+# define sqlite3VdbeIOTraceSql(X)
+#endif
+
+/*
+** These routines are available for the mem2.c debugging memory allocator
+** only.  They are used to verify that different "types" of memory
+** allocations are properly tracked by the system.
+**
+** sqlite3MemdebugSetType() sets the "type" of an allocation to one of
+** the MEMTYPE_* macros defined below.  The type must be a bitmask with
+** a single bit set.
+**
+** sqlite3MemdebugHasType() returns true if any of the bits in its second
+** argument match the type set by the previous sqlite3MemdebugSetType().
+** sqlite3MemdebugHasType() is intended for use inside assert() statements.
+**
+** sqlite3MemdebugNoType() returns true if none of the bits in its second
+** argument match the type set by the previous sqlite3MemdebugSetType().
+**
+** Perhaps the most important point is the difference between MEMTYPE_HEAP
+** and MEMTYPE_LOOKASIDE.  If an allocation is MEMTYPE_LOOKASIDE, that means
+** it might have been allocated by lookaside, except the allocation was
+** too large or lookaside was already full.  It is important to verify
+** that allocations that might have been satisfied by lookaside are not
+** passed back to non-lookaside free() routines.  Asserts such as the
+** example above are placed on the non-lookaside free() routines to verify
+** this constraint.
+**
+** All of this is no-op for a production build.  It only comes into
+** play when the SQLITE_MEMDEBUG compile-time option is used.
+*/
+#ifdef SQLITE_MEMDEBUG
+SQLITE_PRIVATE   void sqlite3MemdebugSetType(void*,u8);
+SQLITE_PRIVATE   int sqlite3MemdebugHasType(void*,u8);
+SQLITE_PRIVATE   int sqlite3MemdebugNoType(void*,u8);
+#else
+# define sqlite3MemdebugSetType(X,Y)  /* no-op */
+# define sqlite3MemdebugHasType(X,Y)  1
+# define sqlite3MemdebugNoType(X,Y)   1
+#endif
+#define MEMTYPE_HEAP       0x01  /* General heap allocations */
+#define MEMTYPE_LOOKASIDE  0x02  /* Heap that might have been lookaside */
+#define MEMTYPE_SCRATCH    0x04  /* Scratch allocations */
+#define MEMTYPE_PCACHE     0x08  /* Page cache allocations */
+
+/*
+** Threading interface
+*/
+#if SQLITE_MAX_WORKER_THREADS>0
+SQLITE_PRIVATE int sqlite3ThreadCreate(SQLiteThread**,void*(*)(void*),void*);
+SQLITE_PRIVATE int sqlite3ThreadJoin(SQLiteThread*, void**);
+#endif
+
+#if defined(SQLITE_ENABLE_DBSTAT_VTAB) || defined(SQLITE_TEST)
+SQLITE_PRIVATE int sqlite3DbstatRegister(sqlite3*);
+#endif
+
+SQLITE_PRIVATE int sqlite3ExprVectorSize(Expr *pExpr);
+SQLITE_PRIVATE int sqlite3ExprIsVector(Expr *pExpr);
+SQLITE_PRIVATE Expr *sqlite3VectorFieldSubexpr(Expr*, int);
+SQLITE_PRIVATE Expr *sqlite3ExprForVectorField(Parse*,Expr*,int);
+
+#endif /* SQLITEINT_H */
+
+/************** End of sqliteInt.h *******************************************/
+/************** Begin file crypto.c ******************************************/
+/* 
+** SQLCipher
+** http://sqlcipher.net
+** 
+** Copyright (c) 2008 - 2013, ZETETIC LLC
+** All rights reserved.
+** 
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are met:
+**     * Redistributions of source code must retain the above copyright
+**       notice, this list of conditions and the following disclaimer.
+**     * Redistributions in binary form must reproduce the above copyright
+**       notice, this list of conditions and the following disclaimer in the
+**       documentation and/or other materials provided with the distribution.
+**     * Neither the name of the ZETETIC LLC nor the
+**       names of its contributors may be used to endorse or promote products
+**       derived from this software without specific prior written permission.
+** 
+** THIS SOFTWARE IS PROVIDED BY ZETETIC LLC ''AS IS'' AND ANY
+** EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+** WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+** DISCLAIMED. IN NO EVENT SHALL ZETETIC LLC BE LIABLE FOR ANY
+** DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+** (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+** SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+**  
+*/
+/* BEGIN SQLCIPHER */
+#ifdef SQLITE_HAS_CODEC
+
+/* #include <assert.h> */
+/* #include "sqliteInt.h" */
+/************** Include btreeInt.h in the middle of crypto.c *****************/
+/************** Begin file btreeInt.h ****************************************/
+/*
+** 2004 April 6
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file implements an external (disk-based) database using BTrees.
+** For a detailed discussion of BTrees, refer to
+**
+**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
+**     "Sorting And Searching", pages 473-480. Addison-Wesley
+**     Publishing Company, Reading, Massachusetts.
+**
+** The basic idea is that each page of the file contains N database
+** entries and N+1 pointers to subpages.
+**
+**   ----------------------------------------------------------------
+**   |  Ptr(0) | Key(0) | Ptr(1) | Key(1) | ... | Key(N-1) | Ptr(N) |
+**   ----------------------------------------------------------------
+**
+** All of the keys on the page that Ptr(0) points to have values less
+** than Key(0).  All of the keys on page Ptr(1) and its subpages have
+** values greater than Key(0) and less than Key(1).  All of the keys
+** on Ptr(N) and its subpages have values greater than Key(N-1).  And
+** so forth.
+**
+** Finding a particular key requires reading O(log(M)) pages from the 
+** disk where M is the number of entries in the tree.
+**
+** In this implementation, a single file can hold one or more separate 
+** BTrees.  Each BTree is identified by the index of its root page.  The
+** key and data for any entry are combined to form the "payload".  A
+** fixed amount of payload can be carried directly on the database
+** page.  If the payload is larger than the preset amount then surplus
+** bytes are stored on overflow pages.  The payload for an entry
+** and the preceding pointer are combined to form a "Cell".  Each 
+** page has a small header which contains the Ptr(N) pointer and other
+** information such as the size of key and data.
+**
+** FORMAT DETAILS
+**
+** The file is divided into pages.  The first page is called page 1,
+** the second is page 2, and so forth.  A page number of zero indicates
+** "no such page".  The page size can be any power of 2 between 512 and 65536.
+** Each page can be either a btree page, a freelist page, an overflow
+** page, or a pointer-map page.
+**
+** The first page is always a btree page.  The first 100 bytes of the first
+** page contain a special header (the "file header") that describes the file.
+** The format of the file header is as follows:
+**
+**   OFFSET   SIZE    DESCRIPTION
+**      0      16     Header string: "SQLite format 3\000"
+**     16       2     Page size in bytes.  (1 means 65536)
+**     18       1     File format write version
+**     19       1     File format read version
+**     20       1     Bytes of unused space at the end of each page
+**     21       1     Max embedded payload fraction (must be 64)
+**     22       1     Min embedded payload fraction (must be 32)
+**     23       1     Min leaf payload fraction (must be 32)
+**     24       4     File change counter
+**     28       4     Reserved for future use
+**     32       4     First freelist page
+**     36       4     Number of freelist pages in the file
+**     40      60     15 4-byte meta values passed to higher layers
+**
+**     40       4     Schema cookie
+**     44       4     File format of schema layer
+**     48       4     Size of page cache
+**     52       4     Largest root-page (auto/incr_vacuum)
+**     56       4     1=UTF-8 2=UTF16le 3=UTF16be
+**     60       4     User version
+**     64       4     Incremental vacuum mode
+**     68       4     Application-ID
+**     72      20     unused
+**     92       4     The version-valid-for number
+**     96       4     SQLITE_VERSION_NUMBER
+**
+** All of the integer values are big-endian (most significant byte first).
+**
+** The file change counter is incremented when the database is changed
+** This counter allows other processes to know when the file has changed
+** and thus when they need to flush their cache.
+**
+** The max embedded payload fraction is the amount of the total usable
+** space in a page that can be consumed by a single cell for standard
+** B-tree (non-LEAFDATA) tables.  A value of 255 means 100%.  The default
+** is to limit the maximum cell size so that at least 4 cells will fit
+** on one page.  Thus the default max embedded payload fraction is 64.
+**
+** If the payload for a cell is larger than the max payload, then extra
+** payload is spilled to overflow pages.  Once an overflow page is allocated,
+** as many bytes as possible are moved into the overflow pages without letting
+** the cell size drop below the min embedded payload fraction.
+**
+** The min leaf payload fraction is like the min embedded payload fraction
+** except that it applies to leaf nodes in a LEAFDATA tree.  The maximum
+** payload fraction for a LEAFDATA tree is always 100% (or 255) and it
+** not specified in the header.
+**
+** Each btree pages is divided into three sections:  The header, the
+** cell pointer array, and the cell content area.  Page 1 also has a 100-byte
+** file header that occurs before the page header.
+**
+**      |----------------|
+**      | file header    |   100 bytes.  Page 1 only.
+**      |----------------|
+**      | page header    |   8 bytes for leaves.  12 bytes for interior nodes
+**      |----------------|
+**      | cell pointer   |   |  2 bytes per cell.  Sorted order.
+**      | array          |   |  Grows downward
+**      |                |   v
+**      |----------------|
+**      | unallocated    |
+**      | space          |
+**      |----------------|   ^  Grows upwards
+**      | cell content   |   |  Arbitrary order interspersed with freeblocks.
+**      | area           |   |  and free space fragments.
+**      |----------------|
+**
+** The page headers looks like this:
+**
+**   OFFSET   SIZE     DESCRIPTION
+**      0       1      Flags. 1: intkey, 2: zerodata, 4: leafdata, 8: leaf
+**      1       2      byte offset to the first freeblock
+**      3       2      number of cells on this page
+**      5       2      first byte of the cell content area
+**      7       1      number of fragmented free bytes
+**      8       4      Right child (the Ptr(N) value).  Omitted on leaves.
+**
+** The flags define the format of this btree page.  The leaf flag means that
+** this page has no children.  The zerodata flag means that this page carries
+** only keys and no data.  The intkey flag means that the key is an integer
+** which is stored in the key size entry of the cell header rather than in
+** the payload area.
+**
+** The cell pointer array begins on the first byte after the page header.
+** The cell pointer array contains zero or more 2-byte numbers which are
+** offsets from the beginning of the page to the cell content in the cell
+** content area.  The cell pointers occur in sorted order.  The system strives
+** to keep free space after the last cell pointer so that new cells can
+** be easily added without having to defragment the page.
+**
+** Cell content is stored at the very end of the page and grows toward the
+** beginning of the page.
+**
+** Unused space within the cell content area is collected into a linked list of
+** freeblocks.  Each freeblock is at least 4 bytes in size.  The byte offset
+** to the first freeblock is given in the header.  Freeblocks occur in
+** increasing order.  Because a freeblock must be at least 4 bytes in size,
+** any group of 3 or fewer unused bytes in the cell content area cannot
+** exist on the freeblock chain.  A group of 3 or fewer free bytes is called
+** a fragment.  The total number of bytes in all fragments is recorded.
+** in the page header at offset 7.
+**
+**    SIZE    DESCRIPTION
+**      2     Byte offset of the next freeblock
+**      2     Bytes in this freeblock
+**
+** Cells are of variable length.  Cells are stored in the cell content area at
+** the end of the page.  Pointers to the cells are in the cell pointer array
+** that immediately follows the page header.  Cells is not necessarily
+** contiguous or in order, but cell pointers are contiguous and in order.
+**
+** Cell content makes use of variable length integers.  A variable
+** length integer is 1 to 9 bytes where the lower 7 bits of each 
+** byte are used.  The integer consists of all bytes that have bit 8 set and
+** the first byte with bit 8 clear.  The most significant byte of the integer
+** appears first.  A variable-length integer may not be more than 9 bytes long.
+** As a special case, all 8 bytes of the 9th byte are used as data.  This
+** allows a 64-bit integer to be encoded in 9 bytes.
+**
+**    0x00                      becomes  0x00000000
+**    0x7f                      becomes  0x0000007f
+**    0x81 0x00                 becomes  0x00000080
+**    0x82 0x00                 becomes  0x00000100
+**    0x80 0x7f                 becomes  0x0000007f
+**    0x8a 0x91 0xd1 0xac 0x78  becomes  0x12345678
+**    0x81 0x81 0x81 0x81 0x01  becomes  0x10204081
+**
+** Variable length integers are used for rowids and to hold the number of
+** bytes of key and data in a btree cell.
+**
+** The content of a cell looks like this:
+**
+**    SIZE    DESCRIPTION
+**      4     Page number of the left child. Omitted if leaf flag is set.
+**     var    Number of bytes of data. Omitted if the zerodata flag is set.
+**     var    Number of bytes of key. Or the key itself if intkey flag is set.
+**      *     Payload
+**      4     First page of the overflow chain.  Omitted if no overflow
+**
+** Overflow pages form a linked list.  Each page except the last is completely
+** filled with data (pagesize - 4 bytes).  The last page can have as little
+** as 1 byte of data.
+**
+**    SIZE    DESCRIPTION
+**      4     Page number of next overflow page
+**      *     Data
+**
+** Freelist pages come in two subtypes: trunk pages and leaf pages.  The
+** file header points to the first in a linked list of trunk page.  Each trunk
+** page points to multiple leaf pages.  The content of a leaf page is
+** unspecified.  A trunk page looks like this:
+**
+**    SIZE    DESCRIPTION
+**      4     Page number of next trunk page
+**      4     Number of leaf pointers on this page
+**      *     zero or more pages numbers of leaves
+*/
+/* #include "sqliteInt.h" */
+
+
+/* The following value is the maximum cell size assuming a maximum page
+** size give above.
+*/
+#define MX_CELL_SIZE(pBt)  ((int)(pBt->pageSize-8))
+
+/* The maximum number of cells on a single page of the database.  This
+** assumes a minimum cell size of 6 bytes  (4 bytes for the cell itself
+** plus 2 bytes for the index to the cell in the page header).  Such
+** small cells will be rare, but they are possible.
+*/
+#define MX_CELL(pBt) ((pBt->pageSize-8)/6)
+
+/* Forward declarations */
+typedef struct MemPage MemPage;
+typedef struct BtLock BtLock;
+typedef struct CellInfo CellInfo;
+
+/*
+** This is a magic string that appears at the beginning of every
+** SQLite database in order to identify the file as a real database.
+**
+** You can change this value at compile-time by specifying a
+** -DSQLITE_FILE_HEADER="..." on the compiler command-line.  The
+** header must be exactly 16 bytes including the zero-terminator so
+** the string itself should be 15 characters long.  If you change
+** the header, then your custom library will not be able to read 
+** databases generated by the standard tools and the standard tools
+** will not be able to read databases created by your custom library.
+*/
+#ifndef SQLITE_FILE_HEADER /* 123456789 123456 */
+#  define SQLITE_FILE_HEADER "SQLite format 3"
+#endif
+
+/*
+** Page type flags.  An ORed combination of these flags appear as the
+** first byte of on-disk image of every BTree page.
+*/
+#define PTF_INTKEY    0x01
+#define PTF_ZERODATA  0x02
+#define PTF_LEAFDATA  0x04
+#define PTF_LEAF      0x08
+
+/*
+** As each page of the file is loaded into memory, an instance of the following
+** structure is appended and initialized to zero.  This structure stores
+** information about the page that is decoded from the raw file page.
+**
+** The pParent field points back to the parent page.  This allows us to
+** walk up the BTree from any leaf to the root.  Care must be taken to
+** unref() the parent page pointer when this page is no longer referenced.
+** The pageDestructor() routine handles that chore.
+**
+** Access to all fields of this structure is controlled by the mutex
+** stored in MemPage.pBt->mutex.
+*/
+struct MemPage {
+  u8 isInit;           /* True if previously initialized. MUST BE FIRST! */
+  u8 nOverflow;        /* Number of overflow cell bodies in aCell[] */
+  u8 intKey;           /* True if table b-trees.  False for index b-trees */
+  u8 intKeyLeaf;       /* True if the leaf of an intKey table */
+  u8 leaf;             /* True if a leaf page */
+  u8 hdrOffset;        /* 100 for page 1.  0 otherwise */
+  u8 childPtrSize;     /* 0 if leaf==1.  4 if leaf==0 */
+  u8 max1bytePayload;  /* min(maxLocal,127) */
+  u8 bBusy;            /* Prevent endless loops on corrupt database files */
+  u16 maxLocal;        /* Copy of BtShared.maxLocal or BtShared.maxLeaf */
+  u16 minLocal;        /* Copy of BtShared.minLocal or BtShared.minLeaf */
+  u16 cellOffset;      /* Index in aData of first cell pointer */
+  u16 nFree;           /* Number of free bytes on the page */
+  u16 nCell;           /* Number of cells on this page, local and ovfl */
+  u16 maskPage;        /* Mask for page offset */
+  u16 aiOvfl[5];       /* Insert the i-th overflow cell before the aiOvfl-th
+                       ** non-overflow cell */
+  u8 *apOvfl[5];       /* Pointers to the body of overflow cells */
+  BtShared *pBt;       /* Pointer to BtShared that this page is part of */
+  u8 *aData;           /* Pointer to disk image of the page data */
+  u8 *aDataEnd;        /* One byte past the end of usable data */
+  u8 *aCellIdx;        /* The cell index area */
+  u8 *aDataOfst;       /* Same as aData for leaves.  aData+4 for interior */
+  DbPage *pDbPage;     /* Pager page handle */
+  u16 (*xCellSize)(MemPage*,u8*);             /* cellSizePtr method */
+  void (*xParseCell)(MemPage*,u8*,CellInfo*); /* btreeParseCell method */
+  Pgno pgno;           /* Page number for this page */
+};
+
+/*
+** The in-memory image of a disk page has the auxiliary information appended
+** to the end.  EXTRA_SIZE is the number of bytes of space needed to hold
+** that extra information.
+*/
+#define EXTRA_SIZE sizeof(MemPage)
+
+/*
+** A linked list of the following structures is stored at BtShared.pLock.
+** Locks are added (or upgraded from READ_LOCK to WRITE_LOCK) when a cursor 
+** is opened on the table with root page BtShared.iTable. Locks are removed
+** from this list when a transaction is committed or rolled back, or when
+** a btree handle is closed.
+*/
+struct BtLock {
+  Btree *pBtree;        /* Btree handle holding this lock */
+  Pgno iTable;          /* Root page of table */
+  u8 eLock;             /* READ_LOCK or WRITE_LOCK */
+  BtLock *pNext;        /* Next in BtShared.pLock list */
+};
+
+/* Candidate values for BtLock.eLock */
+#define READ_LOCK     1
+#define WRITE_LOCK    2
+
+/* A Btree handle
+**
+** A database connection contains a pointer to an instance of
+** this object for every database file that it has open.  This structure
+** is opaque to the database connection.  The database connection cannot
+** see the internals of this structure and only deals with pointers to
+** this structure.
+**
+** For some database files, the same underlying database cache might be 
+** shared between multiple connections.  In that case, each connection
+** has it own instance of this object.  But each instance of this object
+** points to the same BtShared object.  The database cache and the
+** schema associated with the database file are all contained within
+** the BtShared object.
+**
+** All fields in this structure are accessed under sqlite3.mutex.
+** The pBt pointer itself may not be changed while there exists cursors 
+** in the referenced BtShared that point back to this Btree since those
+** cursors have to go through this Btree to find their BtShared and
+** they often do so without holding sqlite3.mutex.
+*/
+struct Btree {
+  sqlite3 *db;       /* The database connection holding this btree */
+  BtShared *pBt;     /* Sharable content of this btree */
+  u8 inTrans;        /* TRANS_NONE, TRANS_READ or TRANS_WRITE */
+  u8 sharable;       /* True if we can share pBt with another db */
+  u8 locked;         /* True if db currently has pBt locked */
+  u8 hasIncrblobCur; /* True if there are one or more Incrblob cursors */
+  int wantToLock;    /* Number of nested calls to sqlite3BtreeEnter() */
+  int nBackup;       /* Number of backup operations reading this btree */
+  u32 iDataVersion;  /* Combines with pBt->pPager->iDataVersion */
+  Btree *pNext;      /* List of other sharable Btrees from the same db */
+  Btree *pPrev;      /* Back pointer of the same list */
+#ifndef SQLITE_OMIT_SHARED_CACHE
+  BtLock lock;       /* Object used to lock page 1 */
+#endif
+};
+
+/*
+** Btree.inTrans may take one of the following values.
+**
+** If the shared-data extension is enabled, there may be multiple users
+** of the Btree structure. At most one of these may open a write transaction,
+** but any number may have active read transactions.
+*/
+#define TRANS_NONE  0
+#define TRANS_READ  1
+#define TRANS_WRITE 2
+
+/*
+** An instance of this object represents a single database file.
+** 
+** A single database file can be in use at the same time by two
+** or more database connections.  When two or more connections are
+** sharing the same database file, each connection has it own
+** private Btree object for the file and each of those Btrees points
+** to this one BtShared object.  BtShared.nRef is the number of
+** connections currently sharing this database file.
+**
+** Fields in this structure are accessed under the BtShared.mutex
+** mutex, except for nRef and pNext which are accessed under the
+** global SQLITE_MUTEX_STATIC_MASTER mutex.  The pPager field
+** may not be modified once it is initially set as long as nRef>0.
+** The pSchema field may be set once under BtShared.mutex and
+** thereafter is unchanged as long as nRef>0.
+**
+** isPending:
+**
+**   If a BtShared client fails to obtain a write-lock on a database
+**   table (because there exists one or more read-locks on the table),
+**   the shared-cache enters 'pending-lock' state and isPending is
+**   set to true.
+**
+**   The shared-cache leaves the 'pending lock' state when either of
+**   the following occur:
+**
+**     1) The current writer (BtShared.pWriter) concludes its transaction, OR
+**     2) The number of locks held by other connections drops to zero.
+**
+**   while in the 'pending-lock' state, no connection may start a new
+**   transaction.
+**
+**   This feature is included to help prevent writer-starvation.
+*/
+struct BtShared {
+  Pager *pPager;        /* The page cache */
+  sqlite3 *db;          /* Database connection currently using this Btree */
+  BtCursor *pCursor;    /* A list of all open cursors */
+  MemPage *pPage1;      /* First page of the database */
+  u8 openFlags;         /* Flags to sqlite3BtreeOpen() */
+#ifndef SQLITE_OMIT_AUTOVACUUM
+  u8 autoVacuum;        /* True if auto-vacuum is enabled */
+  u8 incrVacuum;        /* True if incr-vacuum is enabled */
+  u8 bDoTruncate;       /* True to truncate db on commit */
+#endif
+  u8 inTransaction;     /* Transaction state */
+  u8 max1bytePayload;   /* Maximum first byte of cell for a 1-byte payload */
+#ifdef SQLITE_HAS_CODEC
+  u8 optimalReserve;    /* Desired amount of reserved space per page */
+#endif
+  u16 btsFlags;         /* Boolean parameters.  See BTS_* macros below */
+  u16 maxLocal;         /* Maximum local payload in non-LEAFDATA tables */
+  u16 minLocal;         /* Minimum local payload in non-LEAFDATA tables */
+  u16 maxLeaf;          /* Maximum local payload in a LEAFDATA table */
+  u16 minLeaf;          /* Minimum local payload in a LEAFDATA table */
+  u32 pageSize;         /* Total number of bytes on a page */
+  u32 usableSize;       /* Number of usable bytes on each page */
+  int nTransaction;     /* Number of open transactions (read + write) */
+  u32 nPage;            /* Number of pages in the database */
+  void *pSchema;        /* Pointer to space allocated by sqlite3BtreeSchema() */
+  void (*xFreeSchema)(void*);  /* Destructor for BtShared.pSchema */
+  sqlite3_mutex *mutex; /* Non-recursive mutex required to access this object */
+  Bitvec *pHasContent;  /* Set of pages moved to free-list this transaction */
+#ifndef SQLITE_OMIT_SHARED_CACHE
+  int nRef;             /* Number of references to this structure */
+  BtShared *pNext;      /* Next on a list of sharable BtShared structs */
+  BtLock *pLock;        /* List of locks held on this shared-btree struct */
+  Btree *pWriter;       /* Btree with currently open write transaction */
+#endif
+  u8 *pTmpSpace;        /* Temp space sufficient to hold a single cell */
+};
+
+/*
+** Allowed values for BtShared.btsFlags
+*/
+#define BTS_READ_ONLY        0x0001   /* Underlying file is readonly */
+#define BTS_PAGESIZE_FIXED   0x0002   /* Page size can no longer be changed */
+#define BTS_SECURE_DELETE    0x0004   /* PRAGMA secure_delete is enabled */
+#define BTS_INITIALLY_EMPTY  0x0008   /* Database was empty at trans start */
+#define BTS_NO_WAL           0x0010   /* Do not open write-ahead-log files */
+#define BTS_EXCLUSIVE        0x0020   /* pWriter has an exclusive lock */
+#define BTS_PENDING          0x0040   /* Waiting for read-locks to clear */
+
+/*
+** An instance of the following structure is used to hold information
+** about a cell.  The parseCellPtr() function fills in this structure
+** based on information extract from the raw disk page.
+*/
+struct CellInfo {
+  i64 nKey;      /* The key for INTKEY tables, or nPayload otherwise */
+  u8 *pPayload;  /* Pointer to the start of payload */
+  u32 nPayload;  /* Bytes of payload */
+  u16 nLocal;    /* Amount of payload held locally, not on overflow */
+  u16 nSize;     /* Size of the cell content on the main b-tree page */
+};
+
+/*
+** Maximum depth of an SQLite B-Tree structure. Any B-Tree deeper than
+** this will be declared corrupt. This value is calculated based on a
+** maximum database size of 2^31 pages a minimum fanout of 2 for a
+** root-node and 3 for all other internal nodes.
+**
+** If a tree that appears to be taller than this is encountered, it is
+** assumed that the database is corrupt.
+*/
+#define BTCURSOR_MAX_DEPTH 20
+
+/*
+** A cursor is a pointer to a particular entry within a particular
+** b-tree within a database file.
+**
+** The entry is identified by its MemPage and the index in
+** MemPage.aCell[] of the entry.
+**
+** A single database file can be shared by two more database connections,
+** but cursors cannot be shared.  Each cursor is associated with a
+** particular database connection identified BtCursor.pBtree.db.
+**
+** Fields in this structure are accessed under the BtShared.mutex
+** found at self->pBt->mutex. 
+**
+** skipNext meaning:
+**    eState==SKIPNEXT && skipNext>0:  Next sqlite3BtreeNext() is no-op.
+**    eState==SKIPNEXT && skipNext<0:  Next sqlite3BtreePrevious() is no-op.
+**    eState==FAULT:                   Cursor fault with skipNext as error code.
+*/
+struct BtCursor {
+  Btree *pBtree;            /* The Btree to which this cursor belongs */
+  BtShared *pBt;            /* The BtShared this cursor points to */
+  BtCursor *pNext;          /* Forms a linked list of all cursors */
+  Pgno *aOverflow;          /* Cache of overflow page locations */
+  CellInfo info;            /* A parse of the cell we are pointing at */
+  i64 nKey;                 /* Size of pKey, or last integer key */
+  void *pKey;               /* Saved key that was cursor last known position */
+  Pgno pgnoRoot;            /* The root page of this tree */
+  int nOvflAlloc;           /* Allocated size of aOverflow[] array */
+  int skipNext;    /* Prev() is noop if negative. Next() is noop if positive.
+                   ** Error code if eState==CURSOR_FAULT */
+  u8 curFlags;              /* zero or more BTCF_* flags defined below */
+  u8 curPagerFlags;         /* Flags to send to sqlite3PagerGet() */
+  u8 eState;                /* One of the CURSOR_XXX constants (see below) */
+  u8 hints;                 /* As configured by CursorSetHints() */
+  /* All fields above are zeroed when the cursor is allocated.  See
+  ** sqlite3BtreeCursorZero().  Fields that follow must be manually
+  ** initialized. */
+  i8 iPage;                 /* Index of current page in apPage */
+  u8 curIntKey;             /* Value of apPage[0]->intKey */
+  struct KeyInfo *pKeyInfo; /* Argument passed to comparison function */
+  void *padding1;           /* Make object size a multiple of 16 */
+  u16 aiIdx[BTCURSOR_MAX_DEPTH];        /* Current index in apPage[i] */
+  MemPage *apPage[BTCURSOR_MAX_DEPTH];  /* Pages from root to current page */
+};
+
+/*
+** Legal values for BtCursor.curFlags
+*/
+#define BTCF_WriteFlag    0x01   /* True if a write cursor */
+#define BTCF_ValidNKey    0x02   /* True if info.nKey is valid */
+#define BTCF_ValidOvfl    0x04   /* True if aOverflow is valid */
+#define BTCF_AtLast       0x08   /* Cursor is pointing ot the last entry */
+#define BTCF_Incrblob     0x10   /* True if an incremental I/O handle */
+#define BTCF_Multiple     0x20   /* Maybe another cursor on the same btree */
+
+/*
+** Potential values for BtCursor.eState.
+**
+** CURSOR_INVALID:
+**   Cursor does not point to a valid entry. This can happen (for example) 
+**   because the table is empty or because BtreeCursorFirst() has not been
+**   called.
+**
+** CURSOR_VALID:
+**   Cursor points to a valid entry. getPayload() etc. may be called.
+**
+** CURSOR_SKIPNEXT:
+**   Cursor is valid except that the Cursor.skipNext field is non-zero
+**   indicating that the next sqlite3BtreeNext() or sqlite3BtreePrevious()
+**   operation should be a no-op.
+**
+** CURSOR_REQUIRESEEK:
+**   The table that this cursor was opened on still exists, but has been 
+**   modified since the cursor was last used. The cursor position is saved
+**   in variables BtCursor.pKey and BtCursor.nKey. When a cursor is in 
+**   this state, restoreCursorPosition() can be called to attempt to
+**   seek the cursor to the saved position.
+**
+** CURSOR_FAULT:
+**   An unrecoverable error (an I/O error or a malloc failure) has occurred
+**   on a different connection that shares the BtShared cache with this
+**   cursor.  The error has left the cache in an inconsistent state.
+**   Do nothing else with this cursor.  Any attempt to use the cursor
+**   should return the error code stored in BtCursor.skipNext
+*/
+#define CURSOR_INVALID           0
+#define CURSOR_VALID             1
+#define CURSOR_SKIPNEXT          2
+#define CURSOR_REQUIRESEEK       3
+#define CURSOR_FAULT             4
+
+/* 
+** The database page the PENDING_BYTE occupies. This page is never used.
+*/
+# define PENDING_BYTE_PAGE(pBt) PAGER_MJ_PGNO(pBt)
+
+/*
+** These macros define the location of the pointer-map entry for a 
+** database page. The first argument to each is the number of usable
+** bytes on each page of the database (often 1024). The second is the
+** page number to look up in the pointer map.
+**
+** PTRMAP_PAGENO returns the database page number of the pointer-map
+** page that stores the required pointer. PTRMAP_PTROFFSET returns
+** the offset of the requested map entry.
+**
+** If the pgno argument passed to PTRMAP_PAGENO is a pointer-map page,
+** then pgno is returned. So (pgno==PTRMAP_PAGENO(pgsz, pgno)) can be
+** used to test if pgno is a pointer-map page. PTRMAP_ISPAGE implements
+** this test.
+*/
+#define PTRMAP_PAGENO(pBt, pgno) ptrmapPageno(pBt, pgno)
+#define PTRMAP_PTROFFSET(pgptrmap, pgno) (5*(pgno-pgptrmap-1))
+#define PTRMAP_ISPAGE(pBt, pgno) (PTRMAP_PAGENO((pBt),(pgno))==(pgno))
+
+/*
+** The pointer map is a lookup table that identifies the parent page for
+** each child page in the database file.  The parent page is the page that
+** contains a pointer to the child.  Every page in the database contains
+** 0 or 1 parent pages.  (In this context 'database page' refers
+** to any page that is not part of the pointer map itself.)  Each pointer map
+** entry consists of a single byte 'type' and a 4 byte parent page number.
+** The PTRMAP_XXX identifiers below are the valid types.
+**
+** The purpose of the pointer map is to facility moving pages from one
+** position in the file to another as part of autovacuum.  When a page
+** is moved, the pointer in its parent must be updated to point to the
+** new location.  The pointer map is used to locate the parent page quickly.
+**
+** PTRMAP_ROOTPAGE: The database page is a root-page. The page-number is not
+**                  used in this case.
+**
+** PTRMAP_FREEPAGE: The database page is an unused (free) page. The page-number 
+**                  is not used in this case.
+**
+** PTRMAP_OVERFLOW1: The database page is the first page in a list of 
+**                   overflow pages. The page number identifies the page that
+**                   contains the cell with a pointer to this overflow page.
+**
+** PTRMAP_OVERFLOW2: The database page is the second or later page in a list of
+**                   overflow pages. The page-number identifies the previous
+**                   page in the overflow page list.
+**
+** PTRMAP_BTREE: The database page is a non-root btree page. The page number
+**               identifies the parent page in the btree.
+*/
+#define PTRMAP_ROOTPAGE 1
+#define PTRMAP_FREEPAGE 2
+#define PTRMAP_OVERFLOW1 3
+#define PTRMAP_OVERFLOW2 4
+#define PTRMAP_BTREE 5
+
+/* A bunch of assert() statements to check the transaction state variables
+** of handle p (type Btree*) are internally consistent.
+*/
+#define btreeIntegrity(p) \
+  assert( p->pBt->inTransaction!=TRANS_NONE || p->pBt->nTransaction==0 ); \
+  assert( p->pBt->inTransaction>=p->inTrans ); 
+
+
+/*
+** The ISAUTOVACUUM macro is used within balance_nonroot() to determine
+** if the database supports auto-vacuum or not. Because it is used
+** within an expression that is an argument to another macro 
+** (sqliteMallocRaw), it is not possible to use conditional compilation.
+** So, this macro is defined instead.
+*/
+#ifndef SQLITE_OMIT_AUTOVACUUM
+#define ISAUTOVACUUM (pBt->autoVacuum)
+#else
+#define ISAUTOVACUUM 0
+#endif
+
+
+/*
+** This structure is passed around through all the sanity checking routines
+** in order to keep track of some global state information.
+**
+** The aRef[] array is allocated so that there is 1 bit for each page in
+** the database. As the integrity-check proceeds, for each page used in
+** the database the corresponding bit is set. This allows integrity-check to 
+** detect pages that are used twice and orphaned pages (both of which 
+** indicate corruption).
+*/
+typedef struct IntegrityCk IntegrityCk;
+struct IntegrityCk {
+  BtShared *pBt;    /* The tree being checked out */
+  Pager *pPager;    /* The associated pager.  Also accessible by pBt->pPager */
+  u8 *aPgRef;       /* 1 bit per page in the db (see above) */
+  Pgno nPage;       /* Number of pages in the database */
+  int mxErr;        /* Stop accumulating errors when this reaches zero */
+  int nErr;         /* Number of messages written to zErrMsg so far */
+  int mallocFailed; /* A memory allocation error has occurred */
+  const char *zPfx; /* Error message prefix */
+  int v1, v2;       /* Values for up to two %d fields in zPfx */
+  StrAccum errMsg;  /* Accumulate the error message text here */
+  u32 *heap;        /* Min-heap used for analyzing cell coverage */
+};
+
+/*
+** Routines to read or write a two- and four-byte big-endian integer values.
+*/
+#define get2byte(x)   ((x)[0]<<8 | (x)[1])
+#define put2byte(p,v) ((p)[0] = (u8)((v)>>8), (p)[1] = (u8)(v))
+#define get4byte sqlite3Get4byte
+#define put4byte sqlite3Put4byte
+
+/*
+** get2byteAligned(), unlike get2byte(), requires that its argument point to a
+** two-byte aligned address.  get2bytea() is only used for accessing the
+** cell addresses in a btree header.
+*/
+#if SQLITE_BYTEORDER==4321
+# define get2byteAligned(x)  (*(u16*)(x))
+#elif SQLITE_BYTEORDER==1234 && !defined(SQLITE_DISABLE_INTRINSIC) \
+    && GCC_VERSION>=4008000
+# define get2byteAligned(x)  __builtin_bswap16(*(u16*)(x))
+#elif SQLITE_BYTEORDER==1234 && !defined(SQLITE_DISABLE_INTRINSIC) \
+    && defined(_MSC_VER) && _MSC_VER>=1300
+# define get2byteAligned(x)  _byteswap_ushort(*(u16*)(x))
+#else
+# define get2byteAligned(x)  ((x)[0]<<8 | (x)[1])
+#endif
+
+/************** End of btreeInt.h ********************************************/
+/************** Continuing where we left off in crypto.c *********************/
+/************** Include crypto.h in the middle of crypto.c *******************/
+/************** Begin file crypto.h ******************************************/
+/* 
+** SQLCipher
+** crypto.h developed by Stephen Lombardo (Zetetic LLC) 
+** sjlombardo at zetetic dot net
+** http://zetetic.net
+** 
+** Copyright (c) 2008, ZETETIC LLC
+** All rights reserved.
+** 
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are met:
+**     * Redistributions of source code must retain the above copyright
+**       notice, this list of conditions and the following disclaimer.
+**     * Redistributions in binary form must reproduce the above copyright
+**       notice, this list of conditions and the following disclaimer in the
+**       documentation and/or other materials provided with the distribution.
+**     * Neither the name of the ZETETIC LLC nor the
+**       names of its contributors may be used to endorse or promote products
+**       derived from this software without specific prior written permission.
+** 
+** THIS SOFTWARE IS PROVIDED BY ZETETIC LLC ''AS IS'' AND ANY
+** EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+** WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+** DISCLAIMED. IN NO EVENT SHALL ZETETIC LLC BE LIABLE FOR ANY
+** DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+** (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+** SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+**  
+*/
+/* BEGIN SQLCIPHER */
+#ifdef SQLITE_HAS_CODEC
+#ifndef CRYPTO_H
+#define CRYPTO_H
+
+#if !defined (SQLCIPHER_CRYPTO_CC) \
+   && !defined (SQLCIPHER_CRYPTO_LIBTOMCRYPT) \
+   && !defined (SQLCIPHER_CRYPTO_OPENSSL)
+#define SQLCIPHER_CRYPTO_OPENSSL
+#endif
+
+#define FILE_HEADER_SZ 16
+
+#ifndef CIPHER_VERSION
+#ifdef SQLCIPHER_FIPS
+#define CIPHER_VERSION "3.4.1 FIPS"
+#else
+#define CIPHER_VERSION "3.4.1"
+#endif
+#endif
+
+#ifndef CIPHER
+#define CIPHER "aes-256-cbc"
+#endif
+
+#define CIPHER_DECRYPT 0
+#define CIPHER_ENCRYPT 1
+
+#define CIPHER_READ_CTX 0
+#define CIPHER_WRITE_CTX 1
+#define CIPHER_READWRITE_CTX 2
+
+#ifndef PBKDF2_ITER
+#define PBKDF2_ITER 64000
+#endif
+
+/* possible flags for cipher_ctx->flags */
+#define CIPHER_FLAG_HMAC          0x01
+#define CIPHER_FLAG_LE_PGNO       0x02
+#define CIPHER_FLAG_BE_PGNO       0x04
+
+#ifndef DEFAULT_CIPHER_FLAGS
+#define DEFAULT_CIPHER_FLAGS CIPHER_FLAG_HMAC | CIPHER_FLAG_LE_PGNO
+#endif
+
+
+/* by default, sqlcipher will use a reduced number of iterations to generate
+   the HMAC key / or transform a raw cipher key 
+   */
+#ifndef FAST_PBKDF2_ITER
+#define FAST_PBKDF2_ITER 2
+#endif
+
+/* this if a fixed random array that will be xor'd with the database salt to ensure that the
+   salt passed to the HMAC key derivation function is not the same as that used to derive
+   the encryption key. This can be overridden at compile time but it will make the resulting
+   binary incompatible with the default builds when using HMAC. A future version of SQLcipher
+   will likely allow this to be defined at runtime via pragma */ 
+#ifndef HMAC_SALT_MASK
+#define HMAC_SALT_MASK 0x3a
+#endif
+
+#ifndef CIPHER_MAX_IV_SZ
+#define CIPHER_MAX_IV_SZ 16
+#endif
+
+#ifndef CIPHER_MAX_KEY_SZ
+#define CIPHER_MAX_KEY_SZ 64
+#endif
+
+
+#ifdef CODEC_DEBUG
+#define CODEC_TRACE(X)  {printf X;fflush(stdout);}
+#else
+#define CODEC_TRACE(X)
+#endif
+
+#ifdef CODEC_DEBUG_PAGEDATA
+#define CODEC_HEXDUMP(DESC,BUFFER,LEN)  \
+  { \
+    int __pctr; \
+    printf(DESC); \
+    for(__pctr=0; __pctr < LEN; __pctr++) { \
+      if(__pctr % 16 == 0) printf("\n%05x: ",__pctr); \
+      printf("%02x ",((unsigned char*) BUFFER)[__pctr]); \
+    } \
+    printf("\n"); \
+    fflush(stdout); \
+  }
+#else
+#define CODEC_HEXDUMP(DESC,BUFFER,LEN)
+#endif
+
+/* extensions defined in pager.c */ 
+SQLITE_API void sqlite3pager_get_codec(Pager *pPager, void **ctx);
+SQLITE_API int sqlite3pager_is_mj_pgno(Pager *pPager, Pgno pgno);
+SQLITE_PRIVATE sqlite3_file *sqlite3Pager_get_fd(Pager *pPager);
+SQLITE_API void sqlite3pager_sqlite3PagerSetCodec(
+  Pager *pPager,
+  void *(*xCodec)(void*,void*,Pgno,int),
+  void (*xCodecSizeChng)(void*,int,int),
+  void (*xCodecFree)(void*),
+  void *pCodec
+);
+SQLITE_API void sqlite3pager_sqlite3PagerSetError(Pager *pPager, int error);
+/* end extensions defined in pager.c */
+ 
+/*
+**  Simple shared routines for converting hex char strings to binary data
+ */
+static int cipher_hex2int(char c) {
+  return (c>='0' && c<='9') ? (c)-'0' :
+         (c>='A' && c<='F') ? (c)-'A'+10 :
+         (c>='a' && c<='f') ? (c)-'a'+10 : 0;
+}
+
+static void cipher_hex2bin(const unsigned char *hex, int sz, unsigned char *out){
+  int i;
+  for(i = 0; i < sz; i += 2){
+    out[i/2] = (cipher_hex2int(hex[i])<<4) | cipher_hex2int(hex[i+1]);
+  }
+}
+
+static void cipher_bin2hex(const unsigned char* in, int sz, char *out) {
+    int i;
+    for(i=0; i < sz; i++) {
+      sqlite3_snprintf(3, out + (i*2), "%02x ", in[i]);
+    } 
+}
+
+static int cipher_isHex(const unsigned char *hex, int sz){
+  int i;
+  for(i = 0; i < sz; i++) {
+    unsigned char c = hex[i];
+    if ((c < '0' || c > '9') &&
+        (c < 'A' || c > 'F') &&
+        (c < 'a' || c > 'f')) {
+      return 0;
+    }
+  }
+  return 1;
+}
+
+/* extensions defined in crypto_impl.c */
+typedef struct codec_ctx codec_ctx;
+
+/* activation and initialization */
+void sqlcipher_activate();
+void sqlcipher_deactivate();
+int sqlcipher_codec_ctx_init(codec_ctx **, Db *, Pager *, sqlite3_file *, const void *, int);
+void sqlcipher_codec_ctx_free(codec_ctx **);
+int sqlcipher_codec_key_derive(codec_ctx *);
+int sqlcipher_codec_key_copy(codec_ctx *, int);
+
+/* page cipher implementation */
+int sqlcipher_page_cipher(codec_ctx *, int, Pgno, int, int, unsigned char *, unsigned char *);
+
+/* context setters & getters */
+void sqlcipher_codec_ctx_set_error(codec_ctx *, int);
+
+int sqlcipher_codec_ctx_set_pass(codec_ctx *, const void *, int, int);
+void sqlcipher_codec_get_keyspec(codec_ctx *, void **zKey, int *nKey);
+
+int sqlcipher_codec_ctx_set_pagesize(codec_ctx *, int);
+int sqlcipher_codec_ctx_get_pagesize(codec_ctx *);
+int sqlcipher_codec_ctx_get_reservesize(codec_ctx *);
+
+void sqlcipher_set_default_pagesize(int page_size);
+int sqlcipher_get_default_pagesize();
+
+void sqlcipher_set_default_kdf_iter(int iter);
+int sqlcipher_get_default_kdf_iter();
+
+int sqlcipher_codec_ctx_set_kdf_iter(codec_ctx *, int, int);
+int sqlcipher_codec_ctx_get_kdf_iter(codec_ctx *ctx, int);
+
+void* sqlcipher_codec_ctx_get_kdf_salt(codec_ctx *ctx);
+
+int sqlcipher_codec_ctx_set_fast_kdf_iter(codec_ctx *, int, int);
+int sqlcipher_codec_ctx_get_fast_kdf_iter(codec_ctx *, int);
+
+int sqlcipher_codec_ctx_set_cipher(codec_ctx *, const char *, int);
+const char* sqlcipher_codec_ctx_get_cipher(codec_ctx *ctx, int for_ctx);
+
+void* sqlcipher_codec_ctx_get_data(codec_ctx *);
+
+void sqlcipher_exportFunc(sqlite3_context *, int, sqlite3_value **);
+
+void sqlcipher_set_default_use_hmac(int use);
+int sqlcipher_get_default_use_hmac();
+
+void sqlcipher_set_hmac_salt_mask(unsigned char mask);
+unsigned char sqlcipher_get_hmac_salt_mask();
+
+int sqlcipher_codec_ctx_set_use_hmac(codec_ctx *ctx, int use);
+int sqlcipher_codec_ctx_get_use_hmac(codec_ctx *ctx, int for_ctx);
+
+int sqlcipher_codec_ctx_set_flag(codec_ctx *ctx, unsigned int flag);
+int sqlcipher_codec_ctx_unset_flag(codec_ctx *ctx, unsigned int flag);
+int sqlcipher_codec_ctx_get_flag(codec_ctx *ctx, unsigned int flag, int for_ctx);
+
+const char* sqlcipher_codec_get_cipher_provider(codec_ctx *ctx);
+int sqlcipher_codec_ctx_migrate(codec_ctx *ctx);
+int sqlcipher_codec_add_random(codec_ctx *ctx, const char *data, int random_sz);
+int sqlcipher_cipher_profile(sqlite3 *db, const char *destination);
+static void sqlcipher_profile_callback(void *file, const char *sql, sqlite3_uint64 run_time);
+static int sqlcipher_codec_get_store_pass(codec_ctx *ctx);
+static void sqlcipher_codec_get_pass(codec_ctx *ctx, void **zKey, int *nKey);
+static void sqlcipher_codec_set_store_pass(codec_ctx *ctx, int value);
+int sqlcipher_codec_fips_status(codec_ctx *ctx);
+const char* sqlcipher_codec_get_provider_version(codec_ctx *ctx);
+#endif
+#endif
+/* END SQLCIPHER */
+
+/************** End of crypto.h **********************************************/
+/************** Continuing where we left off in crypto.c *********************/
+
+static const char* codec_get_cipher_version() {
+  return CIPHER_VERSION;
+}
+
+/* Generate code to return a string value */
+static void codec_vdbe_return_static_string(Parse *pParse, const char *zLabel, const char *value){
+  Vdbe *v = sqlite3GetVdbe(pParse);
+  sqlite3VdbeSetNumCols(v, 1);
+  sqlite3VdbeSetColName(v, 0, COLNAME_NAME, zLabel, SQLITE_STATIC);
+  sqlite3VdbeAddOp4(v, OP_String8, 0, 1, 0, value, 0);
+  sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 1);
+}
+
+static int codec_set_btree_to_codec_pagesize(sqlite3 *db, Db *pDb, codec_ctx *ctx) {
+  int rc, page_sz, reserve_sz; 
+
+  page_sz = sqlcipher_codec_ctx_get_pagesize(ctx);
+  reserve_sz = sqlcipher_codec_ctx_get_reservesize(ctx);
+
+  sqlite3_mutex_enter(db->mutex);
+  db->nextPagesize = page_sz; 
+
+  /* before forcing the page size we need to unset the BTS_PAGESIZE_FIXED flag, else  
+     sqliteBtreeSetPageSize will block the change  */
+  pDb->pBt->pBt->btsFlags &= ~BTS_PAGESIZE_FIXED;
+  CODEC_TRACE(("codec_set_btree_to_codec_pagesize: sqlite3BtreeSetPageSize() size=%d reserve=%d\n", page_sz, reserve_sz));
+  rc = sqlite3BtreeSetPageSize(pDb->pBt, page_sz, reserve_sz, 0);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+static int codec_set_pass_key(sqlite3* db, int nDb, const void *zKey, int nKey, int for_ctx) {
+  struct Db *pDb = &db->aDb[nDb];
+  CODEC_TRACE(("codec_set_pass_key: entered db=%p nDb=%d zKey=%s nKey=%d for_ctx=%d\n", db, nDb, (char *)zKey, nKey, for_ctx));
+  if(pDb->pBt) {
+    codec_ctx *ctx;
+    sqlite3pager_get_codec(pDb->pBt->pBt->pPager, (void **) &ctx);
+    if(ctx) return sqlcipher_codec_ctx_set_pass(ctx, zKey, nKey, for_ctx);
+  }
+  return SQLITE_ERROR;
+} 
+
+int sqlcipher_codec_pragma(sqlite3* db, int iDb, Parse *pParse, const char *zLeft, const char *zRight) {
+  char *pragma_cipher_deprecated_msg = "PRAGMA cipher command is deprecated, please remove from usage.";
+  struct Db *pDb = &db->aDb[iDb];
+  codec_ctx *ctx = NULL;
+  int rc;
+
+  if(pDb->pBt) {
+    sqlite3pager_get_codec(pDb->pBt->pBt->pPager, (void **) &ctx);
+  }
+
+  CODEC_TRACE(("sqlcipher_codec_pragma: entered db=%p iDb=%d pParse=%p zLeft=%s zRight=%s ctx=%p\n", db, iDb, pParse, zLeft, zRight, ctx));
+  
+  if( sqlite3StrICmp(zLeft, "cipher_fips_status")== 0 && !zRight ){
+    if(ctx) {
+      char *fips_mode_status = sqlite3_mprintf("%d", sqlcipher_codec_fips_status(ctx));
+      codec_vdbe_return_static_string(pParse, "cipher_fips_status", fips_mode_status);
+      sqlite3_free(fips_mode_status);
+    }
+  } else
+  if( sqlite3StrICmp(zLeft, "cipher_store_pass")==0 && zRight ) {
+    if(ctx) {
+      sqlcipher_codec_set_store_pass(ctx, sqlite3GetBoolean(zRight, 1));
+    }
+  } else
+  if( sqlite3StrICmp(zLeft, "cipher_store_pass")==0 && !zRight ) {
+    if(ctx){
+      char *store_pass_value = sqlite3_mprintf("%d", sqlcipher_codec_get_store_pass(ctx));
+      codec_vdbe_return_static_string(pParse, "cipher_store_pass", store_pass_value);
+      sqlite3_free(store_pass_value);
+    }
+  }
+  if( sqlite3StrICmp(zLeft, "cipher_profile")== 0 && zRight ){
+      char *profile_status = sqlite3_mprintf("%d", sqlcipher_cipher_profile(db, zRight));
+      codec_vdbe_return_static_string(pParse, "cipher_profile", profile_status);
+      sqlite3_free(profile_status);
+  } else
+  if( sqlite3StrICmp(zLeft, "cipher_add_random")==0 && zRight ){
+    if(ctx) {
+      char *add_random_status = sqlite3_mprintf("%d", sqlcipher_codec_add_random(ctx, zRight, sqlite3Strlen30(zRight)));
+      codec_vdbe_return_static_string(pParse, "cipher_add_random", add_random_status);
+      sqlite3_free(add_random_status);
+    }
+  } else
+  if( sqlite3StrICmp(zLeft, "cipher_migrate")==0 && !zRight ){
+    if(ctx){
+      char *migrate_status = sqlite3_mprintf("%d", sqlcipher_codec_ctx_migrate(ctx));
+      codec_vdbe_return_static_string(pParse, "cipher_migrate", migrate_status);
+      sqlite3_free(migrate_status);
+    }
+  } else
+  if( sqlite3StrICmp(zLeft, "cipher_provider")==0 && !zRight ){
+    if(ctx) { codec_vdbe_return_static_string(pParse, "cipher_provider",
+                                              sqlcipher_codec_get_cipher_provider(ctx));
+    }
+  } else
+  if( sqlite3StrICmp(zLeft, "cipher_provider_version")==0 && !zRight){
+    if(ctx) { codec_vdbe_return_static_string(pParse, "cipher_provider_version",
+                                              sqlcipher_codec_get_provider_version(ctx));
+    }
+  } else
+  if( sqlite3StrICmp(zLeft, "cipher_version")==0 && !zRight ){
+    codec_vdbe_return_static_string(pParse, "cipher_version", codec_get_cipher_version());
+  }else
+  if( sqlite3StrICmp(zLeft, "cipher")==0 ){
+    if(ctx) {
+      if( zRight ) {
+        rc = sqlcipher_codec_ctx_set_cipher(ctx, zRight, 2); // change cipher for both
+        codec_vdbe_return_static_string(pParse, "cipher", pragma_cipher_deprecated_msg);
+        sqlite3_log(SQLITE_WARNING, pragma_cipher_deprecated_msg);
+        return rc;
+      }else {
+        codec_vdbe_return_static_string(pParse, "cipher",
+          sqlcipher_codec_ctx_get_cipher(ctx, 2));
+      }
+    }
+  }else
+  if( sqlite3StrICmp(zLeft, "rekey_cipher")==0 && zRight ){
+    if(ctx) sqlcipher_codec_ctx_set_cipher(ctx, zRight, 1); // change write cipher only 
+  }else
+  if( sqlite3StrICmp(zLeft,"cipher_default_kdf_iter")==0 ){
+    if( zRight ) {
+      sqlcipher_set_default_kdf_iter(atoi(zRight)); // change default KDF iterations
+    } else {
+      char *kdf_iter = sqlite3_mprintf("%d", sqlcipher_get_default_kdf_iter());
+      codec_vdbe_return_static_string(pParse, "cipher_default_kdf_iter", kdf_iter);
+      sqlite3_free(kdf_iter);
+    }
+  }else
+  if( sqlite3StrICmp(zLeft, "kdf_iter")==0 ){
+    if(ctx) {
+      if( zRight ) {
+        sqlcipher_codec_ctx_set_kdf_iter(ctx, atoi(zRight), 2); // change of RW PBKDF2 iteration 
+      } else {
+        char *kdf_iter = sqlite3_mprintf("%d", sqlcipher_codec_ctx_get_kdf_iter(ctx, 2));
+        codec_vdbe_return_static_string(pParse, "kdf_iter", kdf_iter);
+        sqlite3_free(kdf_iter);
+      }
+    }
+  }else
+  if( sqlite3StrICmp(zLeft, "fast_kdf_iter")==0){
+    if(ctx) {
+      if( zRight ) {
+        sqlcipher_codec_ctx_set_fast_kdf_iter(ctx, atoi(zRight), 2); // change of RW PBKDF2 iteration 
+      } else {
+        char *fast_kdf_iter = sqlite3_mprintf("%d", sqlcipher_codec_ctx_get_fast_kdf_iter(ctx, 2));
+        codec_vdbe_return_static_string(pParse, "fast_kdf_iter", fast_kdf_iter);
+        sqlite3_free(fast_kdf_iter);
+      }
+    }
+  }else
+  if( sqlite3StrICmp(zLeft, "rekey_kdf_iter")==0 && zRight ){
+    if(ctx) sqlcipher_codec_ctx_set_kdf_iter(ctx, atoi(zRight), 1); // write iterations only
+  }else
+  if( sqlite3StrICmp(zLeft,"cipher_page_size")==0 ){
+    if(ctx) {
+      if( zRight ) {
+        int size = atoi(zRight);
+        rc = sqlcipher_codec_ctx_set_pagesize(ctx, size);
+        if(rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, rc);
+        rc = codec_set_btree_to_codec_pagesize(db, pDb, ctx);
+        if(rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, rc);
+      } else {
+        char * page_size = sqlite3_mprintf("%d", sqlcipher_codec_ctx_get_pagesize(ctx));
+        codec_vdbe_return_static_string(pParse, "cipher_page_size", page_size);
+        sqlite3_free(page_size);
+      }
+    }
+  }else
+  if( sqlite3StrICmp(zLeft,"cipher_default_page_size")==0 ){
+    if( zRight ) {
+      sqlcipher_set_default_pagesize(atoi(zRight));
+    } else {
+      char *default_page_size = sqlite3_mprintf("%d", sqlcipher_get_default_pagesize());
+      codec_vdbe_return_static_string(pParse, "cipher_default_page_size", default_page_size);
+      sqlite3_free(default_page_size);
+    }
+  }else
+  if( sqlite3StrICmp(zLeft,"cipher_default_use_hmac")==0 ){
+    if( zRight ) {
+      sqlcipher_set_default_use_hmac(sqlite3GetBoolean(zRight,1));
+    } else {
+      char *default_use_hmac = sqlite3_mprintf("%d", sqlcipher_get_default_use_hmac());
+      codec_vdbe_return_static_string(pParse, "cipher_default_use_hmac", default_use_hmac);
+      sqlite3_free(default_use_hmac);
+    }
+  }else
+  if( sqlite3StrICmp(zLeft,"cipher_use_hmac")==0 ){
+    if(ctx) {
+      if( zRight ) {
+        rc = sqlcipher_codec_ctx_set_use_hmac(ctx, sqlite3GetBoolean(zRight,1));
+        if(rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, rc);
+        /* since the use of hmac has changed, the page size may also change */
+        rc = codec_set_btree_to_codec_pagesize(db, pDb, ctx);
+        if(rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, rc);
+      } else {
+        char *hmac_flag = sqlite3_mprintf("%d", sqlcipher_codec_ctx_get_use_hmac(ctx, 2));
+        codec_vdbe_return_static_string(pParse, "cipher_use_hmac", hmac_flag);
+        sqlite3_free(hmac_flag);
+      }
+    }
+  }else
+  if( sqlite3StrICmp(zLeft,"cipher_hmac_pgno")==0 ){
+    if(ctx) {
+      if(zRight) {
+        // clear both pgno endian flags
+        if(sqlite3StrICmp(zRight, "le") == 0) {
+          sqlcipher_codec_ctx_unset_flag(ctx, CIPHER_FLAG_BE_PGNO);
+          sqlcipher_codec_ctx_set_flag(ctx, CIPHER_FLAG_LE_PGNO);
+        } else if(sqlite3StrICmp(zRight, "be") == 0) {
+          sqlcipher_codec_ctx_unset_flag(ctx, CIPHER_FLAG_LE_PGNO);
+          sqlcipher_codec_ctx_set_flag(ctx, CIPHER_FLAG_BE_PGNO);
+        } else if(sqlite3StrICmp(zRight, "native") == 0) {
+          sqlcipher_codec_ctx_unset_flag(ctx, CIPHER_FLAG_LE_PGNO);
+          sqlcipher_codec_ctx_unset_flag(ctx, CIPHER_FLAG_BE_PGNO);
+        }
+      } else {
+        if(sqlcipher_codec_ctx_get_flag(ctx, CIPHER_FLAG_LE_PGNO, 2)) {
+          codec_vdbe_return_static_string(pParse, "cipher_hmac_pgno", "le");
+        } else if(sqlcipher_codec_ctx_get_flag(ctx, CIPHER_FLAG_BE_PGNO, 2)) {
+          codec_vdbe_return_static_string(pParse, "cipher_hmac_pgno", "be");
+        } else {
+          codec_vdbe_return_static_string(pParse, "cipher_hmac_pgno", "native");
+        }
+      }
+    }
+  }else
+  if( sqlite3StrICmp(zLeft,"cipher_hmac_salt_mask")==0 ){
+    if(ctx) {
+      if(zRight) {
+        if (sqlite3StrNICmp(zRight ,"x'", 2) == 0 && sqlite3Strlen30(zRight) == 5) {
+          unsigned char mask = 0;
+          const unsigned char *hex = (const unsigned char *)zRight+2;
+          cipher_hex2bin(hex,2,&mask);
+          sqlcipher_set_hmac_salt_mask(mask);
+        }
+      } else {
+          char *hmac_salt_mask = sqlite3_mprintf("%02x", sqlcipher_get_hmac_salt_mask());
+          codec_vdbe_return_static_string(pParse, "cipher_hmac_salt_mask", hmac_salt_mask);
+          sqlite3_free(hmac_salt_mask);
+      }
+    }
+  }else {
+    return 0;
+  }
+  return 1;
+}
+
+
+/*
+ * sqlite3Codec can be called in multiple modes.
+ * encrypt mode - expected to return a pointer to the 
+ *   encrypted data without altering pData.
+ * decrypt mode - expected to return a pointer to pData, with
+ *   the data decrypted in the input buffer
+ */
+void* sqlite3Codec(void *iCtx, void *data, Pgno pgno, int mode) {
+  codec_ctx *ctx = (codec_ctx *) iCtx;
+  int offset = 0, rc = 0;
+  int page_sz = sqlcipher_codec_ctx_get_pagesize(ctx); 
+  unsigned char *pData = (unsigned char *) data;
+  void *buffer = sqlcipher_codec_ctx_get_data(ctx);
+  void *kdf_salt = sqlcipher_codec_ctx_get_kdf_salt(ctx);
+  CODEC_TRACE(("sqlite3Codec: entered pgno=%d, mode=%d, page_sz=%d\n", pgno, mode, page_sz));
+
+  /* call to derive keys if not present yet */
+  if((rc = sqlcipher_codec_key_derive(ctx)) != SQLITE_OK) {
+   sqlcipher_codec_ctx_set_error(ctx, rc); 
+   return NULL;
+  }
+
+  if(pgno == 1) offset = FILE_HEADER_SZ; /* adjust starting pointers in data page for header offset on first page*/
+
+  CODEC_TRACE(("sqlite3Codec: switch mode=%d offset=%d\n",  mode, offset));
+  switch(mode) {
+    case 0: /* decrypt */
+    case 2:
+    case 3:
+      if(pgno == 1) memcpy(buffer, SQLITE_FILE_HEADER, FILE_HEADER_SZ); /* copy file header to the first 16 bytes of the page */ 
+      rc = sqlcipher_page_cipher(ctx, CIPHER_READ_CTX, pgno, CIPHER_DECRYPT, page_sz - offset, pData + offset, (unsigned char*)buffer + offset);
+      if(rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, rc);
+      memcpy(pData, buffer, page_sz); /* copy buffer data back to pData and return */
+      return pData;
+      break;
+    case 6: /* encrypt */
+      if(pgno == 1) memcpy(buffer, kdf_salt, FILE_HEADER_SZ); /* copy salt to output buffer */ 
+      rc = sqlcipher_page_cipher(ctx, CIPHER_WRITE_CTX, pgno, CIPHER_ENCRYPT, page_sz - offset, pData + offset, (unsigned char*)buffer + offset);
+      if(rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, rc);
+      return buffer; /* return persistent buffer data, pData remains intact */
+      break;
+    case 7:
+      if(pgno == 1) memcpy(buffer, kdf_salt, FILE_HEADER_SZ); /* copy salt to output buffer */ 
+      rc = sqlcipher_page_cipher(ctx, CIPHER_READ_CTX, pgno, CIPHER_ENCRYPT, page_sz - offset, pData + offset, (unsigned char*)buffer + offset);
+      if(rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, rc);
+      return buffer; /* return persistent buffer data, pData remains intact */
+      break;
+    default:
+      return pData;
+      break;
+  }
+}
+
+SQLITE_PRIVATE void sqlite3FreeCodecArg(void *pCodecArg) {
+  codec_ctx *ctx = (codec_ctx *) pCodecArg;
+  if(pCodecArg == NULL) return;
+  sqlcipher_codec_ctx_free(&ctx); // wipe and free allocated memory for the context 
+  sqlcipher_deactivate(); /* cleanup related structures, OpenSSL etc, when codec is detatched */
+}
+
+SQLITE_PRIVATE int sqlite3CodecAttach(sqlite3* db, int nDb, const void *zKey, int nKey) {
+  struct Db *pDb = &db->aDb[nDb];
+
+  CODEC_TRACE(("sqlite3CodecAttach: entered nDb=%d zKey=%s, nKey=%d\n", nDb, (char *)zKey, nKey));
+
+
+  if(nKey && zKey && pDb->pBt) {
+    int rc;
+    Pager *pPager = pDb->pBt->pBt->pPager;
+    sqlite3_file *fd = sqlite3Pager_get_fd(pPager);
+    codec_ctx *ctx;
+
+    sqlcipher_activate(); /* perform internal initialization for sqlcipher */
+
+    sqlite3_mutex_enter(db->mutex);
+
+    /* point the internal codec argument against the contet to be prepared */
+    rc = sqlcipher_codec_ctx_init(&ctx, pDb, pDb->pBt->pBt->pPager, fd, zKey, nKey); 
+
+    if(rc != SQLITE_OK) {
+      /* initialization failed, do not attach potentially corrupted context */
+      sqlite3_mutex_leave(db->mutex);
+      return rc;
+    }
+
+    sqlite3pager_sqlite3PagerSetCodec(sqlite3BtreePager(pDb->pBt), sqlite3Codec, NULL, sqlite3FreeCodecArg, (void *) ctx);
+
+    codec_set_btree_to_codec_pagesize(db, pDb, ctx);
+
+    /* force secure delete. This has the benefit of wiping internal data when deleted
+       and also ensures that all pages are written to disk (i.e. not skipped by
+       sqlite3PagerDontWrite optimizations) */ 
+    sqlite3BtreeSecureDelete(pDb->pBt, 1); 
+
+    /* if fd is null, then this is an in-memory database and
+       we dont' want to overwrite the AutoVacuum settings
+       if not null, then set to the default */
+    if(fd != NULL) { 
+      sqlite3BtreeSetAutoVacuum(pDb->pBt, SQLITE_DEFAULT_AUTOVACUUM);
+    }
+    sqlite3_mutex_leave(db->mutex);
+  }
+  return SQLITE_OK;
+}
+
+SQLITE_API void sqlite3_activate_see(const char* in) {
+  /* do nothing, security enhancements are always active */
+}
+
+static int sqlcipher_find_db_index(sqlite3 *db, const char *zDb) {
+  int db_index;
+  if(zDb == NULL){
+    return 0;
+  }
+  for(db_index = 0; db_index < db->nDb; db_index++) {
+    struct Db *pDb = &db->aDb[db_index];
+    if(strcmp(pDb->zDbSName, zDb) == 0) {
+      return db_index;
+    }
+  }
+  return 0;
+}
+
+SQLITE_API int sqlite3_key(sqlite3 *db, const void *pKey, int nKey) {
+  CODEC_TRACE(("sqlite3_key entered: db=%p pKey=%s nKey=%d\n", db, (char *)pKey, nKey));
+  return sqlite3_key_v2(db, "main", pKey, nKey);
+}
+
+SQLITE_API int sqlite3_key_v2(sqlite3 *db, const char *zDb, const void *pKey, int nKey) {
+  CODEC_TRACE(("sqlite3_key_v2: entered db=%p zDb=%s pKey=%s nKey=%d\n", db, zDb, (char *)pKey, nKey));
+  /* attach key if db and pKey are not null and nKey is > 0 */
+  if(db && pKey && nKey) {
+    int db_index = sqlcipher_find_db_index(db, zDb);
+    return sqlite3CodecAttach(db, db_index, pKey, nKey); 
+  }
+  return SQLITE_ERROR;
+}
+
+SQLITE_API int sqlite3_rekey(sqlite3 *db, const void *pKey, int nKey) {
+  CODEC_TRACE(("sqlite3_rekey entered: db=%p pKey=%s nKey=%d\n", db, (char *)pKey, nKey));
+  return sqlite3_rekey_v2(db, "main", pKey, nKey);
+}
+
+/* sqlite3_rekey_v2
+** Given a database, this will reencrypt the database using a new key.
+** There is only one possible modes of operation - to encrypt a database
+** that is already encrpyted. If the database is not already encrypted
+** this should do nothing
+** The proposed logic for this function follows:
+** 1. Determine if the database is already encryptped
+** 2. If there is NOT already a key present do nothing
+** 3. If there is a key present, re-encrypt the database with the new key
+*/
+SQLITE_API int sqlite3_rekey_v2(sqlite3 *db, const char *zDb, const void *pKey, int nKey) {
+  CODEC_TRACE(("sqlite3_rekey_v2: entered db=%p zDb=%s pKey=%s, nKey=%d\n", db, zDb, (char *)pKey, nKey));
+  if(db && pKey && nKey) {
+    int db_index = sqlcipher_find_db_index(db, zDb);
+    struct Db *pDb = &db->aDb[db_index];
+    CODEC_TRACE(("sqlite3_rekey_v2: database pDb=%p db_index:%d\n", pDb, db_index));
+    if(pDb->pBt) {
+      codec_ctx *ctx;
+      int rc, page_count;
+      Pgno pgno;
+      PgHdr *page;
+      Pager *pPager = pDb->pBt->pBt->pPager;
+
+      sqlite3pager_get_codec(pDb->pBt->pBt->pPager, (void **) &ctx);
+     
+      if(ctx == NULL) { 
+        /* there was no codec attached to this database, so this should do nothing! */ 
+        CODEC_TRACE(("sqlite3_rekey_v2: no codec attached to db, exiting\n"));
+        return SQLITE_OK;
+      }
+
+      sqlite3_mutex_enter(db->mutex);
+
+      codec_set_pass_key(db, db_index, pKey, nKey, CIPHER_WRITE_CTX);
+    
+      /* do stuff here to rewrite the database 
+      ** 1. Create a transaction on the database
+      ** 2. Iterate through each page, reading it and then writing it.
+      ** 3. If that goes ok then commit and put ctx->rekey into ctx->key
+      **    note: don't deallocate rekey since it may be used in a subsequent iteration 
+      */
+      rc = sqlite3BtreeBeginTrans(pDb->pBt, 1); /* begin write transaction */
+      sqlite3PagerPagecount(pPager, &page_count);
+      for(pgno = 1; rc == SQLITE_OK && pgno <= (unsigned int)page_count; pgno++) { /* pgno's start at 1 see pager.c:pagerAcquire */
+        if(!sqlite3pager_is_mj_pgno(pPager, pgno)) { /* skip this page (see pager.c:pagerAcquire for reasoning) */
+          rc = sqlite3PagerGet(pPager, pgno, &page, 0);
+          if(rc == SQLITE_OK) { /* write page see pager_incr_changecounter for example */
+            rc = sqlite3PagerWrite(page);
+            if(rc == SQLITE_OK) {
+              sqlite3PagerUnref(page);
+            } else {
+             CODEC_TRACE(("sqlite3_rekey_v2: error %d occurred writing page %d\n", rc, pgno));  
+            }
+          } else {
+             CODEC_TRACE(("sqlite3_rekey_v2: error %d occurred getting page %d\n", rc, pgno));  
+          }
+        } 
+      }
+
+      /* if commit was successful commit and copy the rekey data to current key, else rollback to release locks */
+      if(rc == SQLITE_OK) { 
+        CODEC_TRACE(("sqlite3_rekey_v2: committing\n"));
+        rc = sqlite3BtreeCommit(pDb->pBt); 
+        sqlcipher_codec_key_copy(ctx, CIPHER_WRITE_CTX);
+      } else {
+        CODEC_TRACE(("sqlite3_rekey_v2: rollback\n"));
+        sqlite3BtreeRollback(pDb->pBt, SQLITE_ABORT_ROLLBACK, 0);
+      }
+
+      sqlite3_mutex_leave(db->mutex);
+    }
+    return SQLITE_OK;
+  }
+  return SQLITE_ERROR;
+}
+
+SQLITE_PRIVATE void sqlite3CodecGetKey(sqlite3* db, int nDb, void **zKey, int *nKey) {
+  struct Db *pDb = &db->aDb[nDb];
+  CODEC_TRACE(("sqlite3CodecGetKey: entered db=%p, nDb=%d\n", db, nDb));
+  if( pDb->pBt ) {
+    codec_ctx *ctx;
+    sqlite3pager_get_codec(pDb->pBt->pBt->pPager, (void **) &ctx);
+    if(ctx) {
+      if(sqlcipher_codec_get_store_pass(ctx) == 1) {
+        sqlcipher_codec_get_pass(ctx, zKey, nKey);
+      } else {
+        sqlcipher_codec_get_keyspec(ctx, zKey, nKey);
+      }
+    } else {
+      *zKey = NULL;
+      *nKey = 0;
+    }
+  }
+}
+
+#ifndef OMIT_EXPORT
+
+/*
+ * Implementation of an "export" function that allows a caller
+ * to duplicate the main database to an attached database. This is intended
+ * as a conveneince for users who need to:
+ * 
+ *   1. migrate from an non-encrypted database to an encrypted database
+ *   2. move from an encrypted database to a non-encrypted database
+ *   3. convert beween the various flavors of encrypted databases.  
+ *
+ * This implementation is based heavily on the procedure and code used
+ * in vacuum.c, but is exposed as a function that allows export to any
+ * named attached database.
+ */
+
+/*
+** Finalize a prepared statement.  If there was an error, store the
+** text of the error message in *pzErrMsg.  Return the result code.
+** 
+** Based on vacuumFinalize from vacuum.c
+*/
+static int sqlcipher_finalize(sqlite3 *db, sqlite3_stmt *pStmt, char **pzErrMsg){
+  int rc;
+  rc = sqlite3VdbeFinalize((Vdbe*)pStmt);
+  if( rc ){
+    sqlite3SetString(pzErrMsg, db, sqlite3_errmsg(db));
+  }
+  return rc;
+}
+
+/*
+** Execute zSql on database db. Return an error code.
+** 
+** Based on execSql from vacuum.c
+*/
+static int sqlcipher_execSql(sqlite3 *db, char **pzErrMsg, const char *zSql){
+  sqlite3_stmt *pStmt;
+  VVA_ONLY( int rc; )
+  if( !zSql ){
+    return SQLITE_NOMEM;
+  }
+  if( SQLITE_OK!=sqlite3_prepare(db, zSql, -1, &pStmt, 0) ){
+    sqlite3SetString(pzErrMsg, db, sqlite3_errmsg(db));
+    return sqlite3_errcode(db);
+  }
+  VVA_ONLY( rc = ) sqlite3_step(pStmt);
+  assert( rc!=SQLITE_ROW );
+  return sqlcipher_finalize(db, pStmt, pzErrMsg);
+}
+
+/*
+** Execute zSql on database db. The statement returns exactly
+** one column. Execute this as SQL on the same database.
+** 
+** Based on execExecSql from vacuum.c
+*/
+static int sqlcipher_execExecSql(sqlite3 *db, char **pzErrMsg, const char *zSql){
+  sqlite3_stmt *pStmt;
+  int rc;
+
+  rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
+  if( rc!=SQLITE_OK ) return rc;
+
+  while( SQLITE_ROW==sqlite3_step(pStmt) ){
+    rc = sqlcipher_execSql(db, pzErrMsg, (char*)sqlite3_column_text(pStmt, 0));
+    if( rc!=SQLITE_OK ){
+      sqlcipher_finalize(db, pStmt, pzErrMsg);
+      return rc;
+    }
+  }
+
+  return sqlcipher_finalize(db, pStmt, pzErrMsg);
+}
+
+/*
+ * copy database and schema from the main database to an attached database
+ * 
+ * Based on sqlite3RunVacuum from vacuum.c
+*/
+void sqlcipher_exportFunc(sqlite3_context *context, int argc, sqlite3_value **argv) {
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  const char* attachedDb = (const char*) sqlite3_value_text(argv[0]);
+  int saved_flags;        /* Saved value of the db->flags */
+  int saved_nChange;      /* Saved value of db->nChange */
+  int saved_nTotalChange; /* Saved value of db->nTotalChange */
+  int (*saved_xTrace)(u32,void*,void*,void*); /* Saved db->xTrace */
+  int rc = SQLITE_OK;     /* Return code from service routines */
+  char *zSql = NULL;         /* SQL statements */
+  char *pzErrMsg = NULL;
+  
+  saved_flags = db->flags;
+  saved_nChange = db->nChange;
+  saved_nTotalChange = db->nTotalChange;
+  saved_xTrace = db->xTrace;
+  db->flags |= SQLITE_WriteSchema | SQLITE_IgnoreChecks | SQLITE_PreferBuiltin;
+  db->flags &= ~(SQLITE_ForeignKeys | SQLITE_ReverseOrder);
+  db->xTrace = 0;
+
+  /* Query the schema of the main database. Create a mirror schema
+  ** in the temporary database.
+  */
+  zSql = sqlite3_mprintf(
+    "SELECT 'CREATE TABLE %s.' || substr(sql,14) "
+    "  FROM sqlite_master WHERE type='table' AND name!='sqlite_sequence'"
+    "   AND rootpage>0"
+  , attachedDb);
+  rc = (zSql == NULL) ? SQLITE_NOMEM : sqlcipher_execExecSql(db, &pzErrMsg, zSql); 
+  if( rc!=SQLITE_OK ) goto end_of_export;
+  sqlite3_free(zSql);
+
+  zSql = sqlite3_mprintf(
+    "SELECT 'CREATE INDEX %s.' || substr(sql,14)"
+    "  FROM sqlite_master WHERE sql LIKE 'CREATE INDEX %%' "
+  , attachedDb);
+  rc = (zSql == NULL) ? SQLITE_NOMEM : sqlcipher_execExecSql(db, &pzErrMsg, zSql); 
+  if( rc!=SQLITE_OK ) goto end_of_export;
+  sqlite3_free(zSql);
+
+  zSql = sqlite3_mprintf(
+    "SELECT 'CREATE UNIQUE INDEX %s.' || substr(sql,21) "
+    "  FROM sqlite_master WHERE sql LIKE 'CREATE UNIQUE INDEX %%'"
+  , attachedDb);
+  rc = (zSql == NULL) ? SQLITE_NOMEM : sqlcipher_execExecSql(db, &pzErrMsg, zSql); 
+  if( rc!=SQLITE_OK ) goto end_of_export;
+  sqlite3_free(zSql);
+
+  /* Loop through the tables in the main database. For each, do
+  ** an "INSERT INTO rekey_db.xxx SELECT * FROM main.xxx;" to copy
+  ** the contents to the temporary database.
+  */
+  zSql = sqlite3_mprintf(
+    "SELECT 'INSERT INTO %s.' || quote(name) "
+    "|| ' SELECT * FROM main.' || quote(name) || ';'"
+    "FROM main.sqlite_master "
+    "WHERE type = 'table' AND name!='sqlite_sequence' "
+    "  AND rootpage>0"
+  , attachedDb);
+  rc = (zSql == NULL) ? SQLITE_NOMEM : sqlcipher_execExecSql(db, &pzErrMsg, zSql); 
+  if( rc!=SQLITE_OK ) goto end_of_export;
+  sqlite3_free(zSql);
+
+  /* Copy over the sequence table
+  */
+  zSql = sqlite3_mprintf(
+    "SELECT 'DELETE FROM %s.' || quote(name) || ';' "
+    "FROM %s.sqlite_master WHERE name='sqlite_sequence' "
+  , attachedDb, attachedDb);
+  rc = (zSql == NULL) ? SQLITE_NOMEM : sqlcipher_execExecSql(db, &pzErrMsg, zSql); 
+  if( rc!=SQLITE_OK ) goto end_of_export;
+  sqlite3_free(zSql);
+
+  zSql = sqlite3_mprintf(
+    "SELECT 'INSERT INTO %s.' || quote(name) "
+    "|| ' SELECT * FROM main.' || quote(name) || ';' "
+    "FROM %s.sqlite_master WHERE name=='sqlite_sequence';"
+  , attachedDb, attachedDb);
+  rc = (zSql == NULL) ? SQLITE_NOMEM : sqlcipher_execExecSql(db, &pzErrMsg, zSql); 
+  if( rc!=SQLITE_OK ) goto end_of_export;
+  sqlite3_free(zSql);
+
+  /* Copy the triggers, views, and virtual tables from the main database
+  ** over to the temporary database.  None of these objects has any
+  ** associated storage, so all we have to do is copy their entries
+  ** from the SQLITE_MASTER table.
+  */
+  zSql = sqlite3_mprintf(
+    "INSERT INTO %s.sqlite_master "
+    "  SELECT type, name, tbl_name, rootpage, sql"
+    "    FROM main.sqlite_master"
+    "   WHERE type='view' OR type='trigger'"
+    "      OR (type='table' AND rootpage=0)"
+  , attachedDb);
+  rc = (zSql == NULL) ? SQLITE_NOMEM : sqlcipher_execSql(db, &pzErrMsg, zSql); 
+  if( rc!=SQLITE_OK ) goto end_of_export;
+  sqlite3_free(zSql);
+
+  zSql = NULL;
+end_of_export:
+  db->flags = saved_flags;
+  db->nChange = saved_nChange;
+  db->nTotalChange = saved_nTotalChange;
+  db->xTrace = saved_xTrace;
+
+  sqlite3_free(zSql);
+
+  if(rc) {
+    if(pzErrMsg != NULL) {
+      sqlite3_result_error(context, pzErrMsg, -1);
+      sqlite3DbFree(db, pzErrMsg);
+    } else {
+      sqlite3_result_error(context, sqlite3ErrStr(rc), -1);
+    }
+  }
+}
+
+#endif
+
+/* END SQLCIPHER */
+#endif
+
+/************** End of crypto.c **********************************************/
+/************** Begin file crypto_impl.c *************************************/
+/* 
+** SQLCipher
+** http://sqlcipher.net
+** 
+** Copyright (c) 2008 - 2013, ZETETIC LLC
+** All rights reserved.
+** 
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are met:
+**     * Redistributions of source code must retain the above copyright
+**       notice, this list of conditions and the following disclaimer.
+**     * Redistributions in binary form must reproduce the above copyright
+**       notice, this list of conditions and the following disclaimer in the
+**       documentation and/or other materials provided with the distribution.
+**     * Neither the name of the ZETETIC LLC nor the
+**       names of its contributors may be used to endorse or promote products
+**       derived from this software without specific prior written permission.
+** 
+** THIS SOFTWARE IS PROVIDED BY ZETETIC LLC ''AS IS'' AND ANY
+** EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+** WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+** DISCLAIMED. IN NO EVENT SHALL ZETETIC LLC BE LIABLE FOR ANY
+** DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+** (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+** SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+**  
+*/
+/* BEGIN SQLCIPHER */
+#ifdef SQLITE_HAS_CODEC
+
+/* #include "sqliteInt.h" */
+/* #include "btreeInt.h" */
+/************** Include sqlcipher.h in the middle of crypto_impl.c ***********/
+/************** Begin file sqlcipher.h ***************************************/
+/* 
+** SQLCipher
+** sqlcipher.h developed by Stephen Lombardo (Zetetic LLC) 
+** sjlombardo at zetetic dot net
+** http://zetetic.net
+** 
+** Copyright (c) 2008, ZETETIC LLC
+** All rights reserved.
+** 
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are met:
+**     * Redistributions of source code must retain the above copyright
+**       notice, this list of conditions and the following disclaimer.
+**     * Redistributions in binary form must reproduce the above copyright
+**       notice, this list of conditions and the following disclaimer in the
+**       documentation and/or other materials provided with the distribution.
+**     * Neither the name of the ZETETIC LLC nor the
+**       names of its contributors may be used to endorse or promote products
+**       derived from this software without specific prior written permission.
+** 
+** THIS SOFTWARE IS PROVIDED BY ZETETIC LLC ''AS IS'' AND ANY
+** EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+** WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+** DISCLAIMED. IN NO EVENT SHALL ZETETIC LLC BE LIABLE FOR ANY
+** DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+** (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+** SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+**  
+*/
+/* BEGIN SQLCIPHER */
+#ifdef SQLITE_HAS_CODEC
+#ifndef SQLCIPHER_H
+#define SQLCIPHER_H
+
+
+typedef struct {
+  int (*activate)(void *ctx);
+  int (*deactivate)(void *ctx);
+  const char* (*get_provider_name)(void *ctx);
+  int (*add_random)(void *ctx, void *buffer, int length);
+  int (*random)(void *ctx, void *buffer, int length);
+  int (*hmac)(void *ctx, unsigned char *hmac_key, int key_sz, unsigned char *in, int in_sz, unsigned char *in2, int in2_sz, unsigned char *out);
+  int (*kdf)(void *ctx, const unsigned char *pass, int pass_sz, unsigned char* salt, int salt_sz, int workfactor, int key_sz, unsigned char *key);
+  int (*cipher)(void *ctx, int mode, unsigned char *key, int key_sz, unsigned char *iv, unsigned char *in, int in_sz, unsigned char *out);
+  int (*set_cipher)(void *ctx, const char *cipher_name);
+  const char* (*get_cipher)(void *ctx);
+  int (*get_key_sz)(void *ctx);
+  int (*get_iv_sz)(void *ctx);
+  int (*get_block_sz)(void *ctx);
+  int (*get_hmac_sz)(void *ctx);
+  int (*ctx_copy)(void *target_ctx, void *source_ctx);
+  int (*ctx_cmp)(void *c1, void *c2);
+  int (*ctx_init)(void **ctx);
+  int (*ctx_free)(void **ctx);
+  int (*fips_status)(void *ctx);
+  const char* (*get_provider_version)(void *ctx);
+} sqlcipher_provider;
+
+/* utility functions */
+void sqlcipher_free(void *ptr, int sz);
+void* sqlcipher_malloc(int sz);
+void* sqlcipher_memset(void *v, unsigned char value, int len);
+int sqlcipher_ismemset(const void *v, unsigned char value, int len);
+int sqlcipher_memcmp(const void *v0, const void *v1, int len);
+void sqlcipher_free(void *, int);
+
+/* provider interfaces */
+int sqlcipher_register_provider(sqlcipher_provider *p);
+sqlcipher_provider* sqlcipher_get_provider();
+
+#endif
+#endif
+/* END SQLCIPHER */
+
+
+/************** End of sqlcipher.h *******************************************/
+/************** Continuing where we left off in crypto_impl.c ****************/
+/* #include "crypto.h" */
+#ifndef OMIT_MEMLOCK
+#if defined(__unix__) || defined(__APPLE__) || defined(_AIX)
+#include <sys/mman.h>
+#elif defined(_WIN32)
+# include <windows.h>
+#endif
+#endif
+
+/* the default implementation of SQLCipher uses a cipher_ctx
+   to keep track of read / write state separately. The following
+   struct and associated functions are defined here */
+typedef struct {
+  int store_pass;
+  int derive_key;
+  int kdf_iter;
+  int fast_kdf_iter;
+  int key_sz;
+  int iv_sz;
+  int block_sz;
+  int pass_sz;
+  int reserve_sz;
+  int hmac_sz;
+  int keyspec_sz;
+  unsigned int flags;
+  unsigned char *key;
+  unsigned char *hmac_key;
+  unsigned char *pass;
+  char *keyspec;
+  sqlcipher_provider *provider;
+  void *provider_ctx;
+} cipher_ctx;
+
+static unsigned int default_flags = DEFAULT_CIPHER_FLAGS;
+static unsigned char hmac_salt_mask = HMAC_SALT_MASK;
+static int default_kdf_iter = PBKDF2_ITER;
+static int default_page_size = 1024;
+static unsigned int sqlcipher_activate_count = 0;
+static sqlite3_mutex* sqlcipher_provider_mutex = NULL;
+static sqlcipher_provider *default_provider = NULL;
+
+struct codec_ctx {
+  int kdf_salt_sz;
+  int page_sz;
+  unsigned char *kdf_salt;
+  unsigned char *hmac_kdf_salt;
+  unsigned char *buffer;
+  Btree *pBt;
+  cipher_ctx *read_ctx;
+  cipher_ctx *write_ctx;
+  unsigned int skip_read_hmac;
+  unsigned int need_kdf_salt;
+};
+
+int sqlcipher_register_provider(sqlcipher_provider *p) {
+  sqlite3_mutex_enter(sqlcipher_provider_mutex);
+  if(default_provider != NULL && default_provider != p) {
+    /* only free the current registerd provider if it has been initialized
+       and it isn't a pointer to the same provider passed to the function
+       (i.e. protect against a caller calling register twice for the same provider) */
+    sqlcipher_free(default_provider, sizeof(sqlcipher_provider));
+  }
+  default_provider = p;   
+  sqlite3_mutex_leave(sqlcipher_provider_mutex);
+  return SQLITE_OK;
+}
+
+/* return a pointer to the currently registered provider. This will
+   allow an application to fetch the current registered provider and
+   make minor changes to it */
+sqlcipher_provider* sqlcipher_get_provider() {
+  return default_provider;
+}
+
+void sqlcipher_activate() {
+  sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
+
+  if(sqlcipher_provider_mutex == NULL) {
+    /* allocate a new mutex to guard access to the provider */
+    sqlcipher_provider_mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
+  }
+
+  /* check to see if there is a provider registered at this point
+     if there no provider registered at this point, register the 
+     default provider */
+  if(sqlcipher_get_provider() == NULL) {
+    sqlcipher_provider *p = sqlcipher_malloc(sizeof(sqlcipher_provider)); 
+#if defined (SQLCIPHER_CRYPTO_CC)
+    extern int sqlcipher_cc_setup(sqlcipher_provider *p);
+    sqlcipher_cc_setup(p);
+#elif defined (SQLCIPHER_CRYPTO_LIBTOMCRYPT)
+    extern int sqlcipher_ltc_setup(sqlcipher_provider *p);
+    sqlcipher_ltc_setup(p);
+#elif defined (SQLCIPHER_CRYPTO_OPENSSL)
+    extern int sqlcipher_openssl_setup(sqlcipher_provider *p);
+    sqlcipher_openssl_setup(p);
+#else
+#error "NO DEFAULT SQLCIPHER CRYPTO PROVIDER DEFINED"
+#endif
+    sqlcipher_register_provider(p);
+  }
+
+  sqlcipher_activate_count++; /* increment activation count */
+
+  sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
+}
+
+void sqlcipher_deactivate() {
+  sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
+  sqlcipher_activate_count--;
+  /* if no connections are using sqlcipher, cleanup globals */
+  if(sqlcipher_activate_count < 1) {
+    sqlite3_mutex_enter(sqlcipher_provider_mutex);
+    if(default_provider != NULL) {
+      sqlcipher_free(default_provider, sizeof(sqlcipher_provider));
+      default_provider = NULL;
+    }
+    sqlite3_mutex_leave(sqlcipher_provider_mutex);
+    
+    /* last connection closed, free provider mutex*/
+    sqlite3_mutex_free(sqlcipher_provider_mutex); 
+    sqlcipher_provider_mutex = NULL;
+
+    sqlcipher_activate_count = 0; /* reset activation count */
+  }
+  sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
+}
+
+/* constant time memset using volitile to avoid having the memset
+   optimized out by the compiler. 
+   Note: As suggested by Joachim Schipper (joachim.schipper@fox-it.com)
+*/
+void* sqlcipher_memset(void *v, unsigned char value, int len) {
+  int i = 0;
+  volatile unsigned char *a = v;
+
+  if (v == NULL) return v;
+
+  for(i = 0; i < len; i++) {
+    a[i] = value;
+  }
+
+  return v;
+}
+
+/* constant time memory check tests every position of a memory segement
+   matches a single value (i.e. the memory is all zeros)
+   returns 0 if match, 1 of no match */
+int sqlcipher_ismemset(const void *v, unsigned char value, int len) {
+  const unsigned char *a = v;
+  int i = 0, result = 0;
+
+  for(i = 0; i < len; i++) {
+    result |= a[i] ^ value;
+  }
+
+  return (result != 0);
+}
+
+/* constant time memory comparison routine. 
+   returns 0 if match, 1 if no match */
+int sqlcipher_memcmp(const void *v0, const void *v1, int len) {
+  const unsigned char *a0 = v0, *a1 = v1;
+  int i = 0, result = 0;
+
+  for(i = 0; i < len; i++) {
+    result |= a0[i] ^ a1[i];
+  }
+  
+  return (result != 0);
+}
+
+/**
+  * Free and wipe memory. Uses SQLites internal sqlite3_free so that memory
+  * can be countend and memory leak detection works in the test suite. 
+  * If ptr is not null memory will be freed. 
+  * If sz is greater than zero, the memory will be overwritten with zero before it is freed
+  * If sz is > 0, and not compiled with OMIT_MEMLOCK, system will attempt to unlock the
+  * memory segment so it can be paged
+  */
+void sqlcipher_free(void *ptr, int sz) {
+  if(ptr) {
+    if(sz > 0) {
+      sqlcipher_memset(ptr, 0, sz);
+#ifndef OMIT_MEMLOCK
+#if defined(__unix__) || defined(__APPLE__) 
+      munlock(ptr, sz);
+#elif defined(_WIN32)
+#if !(defined(WINAPI_FAMILY) && (WINAPI_FAMILY == WINAPI_FAMILY_PHONE_APP || WINAPI_FAMILY == WINAPI_FAMILY_APP))
+VirtualUnlock(ptr, sz);
+#endif
+#endif
+#endif
+    }
+    sqlite3_free(ptr);
+  }
+}
+
+/**
+  * allocate memory. Uses sqlite's internall malloc wrapper so memory can be 
+  * reference counted and leak detection works. Unless compiled with OMIT_MEMLOCK
+  * attempts to lock the memory pages so sensitive information won't be swapped
+  */
+void* sqlcipher_malloc(int sz) {
+  void *ptr = sqlite3Malloc(sz);
+  sqlcipher_memset(ptr, 0, sz);
+#ifndef OMIT_MEMLOCK
+  if(ptr) {
+#if defined(__unix__) || defined(__APPLE__) 
+    mlock(ptr, sz);
+#elif defined(_WIN32)
+#if !(defined(WINAPI_FAMILY) && (WINAPI_FAMILY == WINAPI_FAMILY_PHONE_APP || WINAPI_FAMILY == WINAPI_FAMILY_APP))
+    VirtualLock(ptr, sz);
+#endif
+#endif
+  }
+#endif
+  return ptr;
+}
+
+
+/**
+  * Initialize new cipher_ctx struct. This function will allocate memory
+  * for the cipher context and for the key
+  * 
+  * returns SQLITE_OK if initialization was successful
+  * returns SQLITE_NOMEM if an error occured allocating memory
+  */
+static int sqlcipher_cipher_ctx_init(cipher_ctx **iCtx) {
+  int rc;
+  cipher_ctx *ctx;
+  *iCtx = (cipher_ctx *) sqlcipher_malloc(sizeof(cipher_ctx));
+  ctx = *iCtx;
+  if(ctx == NULL) return SQLITE_NOMEM;
+
+  ctx->provider = (sqlcipher_provider *) sqlcipher_malloc(sizeof(sqlcipher_provider));
+  if(ctx->provider == NULL) return SQLITE_NOMEM;
+
+  /* make a copy of the provider to be used for the duration of the context */
+  sqlite3_mutex_enter(sqlcipher_provider_mutex);
+  memcpy(ctx->provider, default_provider, sizeof(sqlcipher_provider));
+  sqlite3_mutex_leave(sqlcipher_provider_mutex);
+
+  if((rc = ctx->provider->ctx_init(&ctx->provider_ctx)) != SQLITE_OK) return rc;
+  ctx->key = (unsigned char *) sqlcipher_malloc(CIPHER_MAX_KEY_SZ);
+  ctx->hmac_key = (unsigned char *) sqlcipher_malloc(CIPHER_MAX_KEY_SZ);
+  if(ctx->key == NULL) return SQLITE_NOMEM;
+  if(ctx->hmac_key == NULL) return SQLITE_NOMEM;
+
+  /* setup default flags */
+  ctx->flags = default_flags;
+
+  return SQLITE_OK;
+}
+
+/**
+  * Free and wipe memory associated with a cipher_ctx
+  */
+static void sqlcipher_cipher_ctx_free(cipher_ctx **iCtx) {
+  cipher_ctx *ctx = *iCtx;
+  CODEC_TRACE(("cipher_ctx_free: entered iCtx=%p\n", iCtx));
+  ctx->provider->ctx_free(&ctx->provider_ctx);
+  sqlcipher_free(ctx->provider, sizeof(sqlcipher_provider)); 
+  sqlcipher_free(ctx->key, ctx->key_sz);
+  sqlcipher_free(ctx->hmac_key, ctx->key_sz);
+  sqlcipher_free(ctx->pass, ctx->pass_sz);
+  sqlcipher_free(ctx->keyspec, ctx->keyspec_sz);
+  sqlcipher_free(ctx, sizeof(cipher_ctx)); 
+}
+
+/**
+  * Compare one cipher_ctx to another.
+  *
+  * returns 0 if all the parameters (except the derived key data) are the same
+  * returns 1 otherwise
+  */
+static int sqlcipher_cipher_ctx_cmp(cipher_ctx *c1, cipher_ctx *c2) {
+  int are_equal = (
+    c1->iv_sz == c2->iv_sz
+    && c1->kdf_iter == c2->kdf_iter
+    && c1->fast_kdf_iter == c2->fast_kdf_iter
+    && c1->key_sz == c2->key_sz
+    && c1->pass_sz == c2->pass_sz
+    && c1->flags == c2->flags
+    && c1->hmac_sz == c2->hmac_sz
+    && c1->provider->ctx_cmp(c1->provider_ctx, c2->provider_ctx) 
+    && (
+      c1->pass == c2->pass
+      || !sqlcipher_memcmp((const unsigned char*)c1->pass,
+                           (const unsigned char*)c2->pass,
+                           c1->pass_sz)
+    ));
+
+  CODEC_TRACE(("sqlcipher_cipher_ctx_cmp: entered \
+                  c1=%p c2=%p \
+                  c1->iv_sz=%d c2->iv_sz=%d \
+                  c1->kdf_iter=%d c2->kdf_iter=%d \
+                  c1->fast_kdf_iter=%d c2->fast_kdf_iter=%d \
+                  c1->key_sz=%d c2->key_sz=%d \
+                  c1->pass_sz=%d c2->pass_sz=%d \
+                  c1->flags=%d c2->flags=%d \
+                  c1->hmac_sz=%d c2->hmac_sz=%d \
+                  c1->provider_ctx=%p c2->provider_ctx=%p \
+                  c1->pass=%p c2->pass=%p \
+                  c1->pass=%s c2->pass=%s \
+                  provider->ctx_cmp=%d \
+                  sqlcipher_memcmp=%d \
+                  are_equal=%d \
+                   \n", 
+                  c1, c2,
+                  c1->iv_sz, c2->iv_sz,
+                  c1->kdf_iter, c2->kdf_iter,
+                  c1->fast_kdf_iter, c2->fast_kdf_iter,
+                  c1->key_sz, c2->key_sz,
+                  c1->pass_sz, c2->pass_sz,
+                  c1->flags, c2->flags,
+                  c1->hmac_sz, c2->hmac_sz,
+                  c1->provider_ctx, c2->provider_ctx,
+                  c1->pass, c2->pass,
+                  c1->pass, c2->pass,
+                  c1->provider->ctx_cmp(c1->provider_ctx, c2->provider_ctx),
+                  sqlcipher_memcmp((const unsigned char*)c1->pass,
+                           (const unsigned char*)c2->pass,
+                           c1->pass_sz),
+                  are_equal
+                  ));
+
+  return !are_equal; /* return 0 if they are the same, 1 otherwise */
+}
+
+/**
+  * Copy one cipher_ctx to another. For instance, assuming that read_ctx is a 
+  * fully initialized context, you could copy it to write_ctx and all yet data
+  * and pass information across
+  *
+  * returns SQLITE_OK if initialization was successful
+  * returns SQLITE_NOMEM if an error occured allocating memory
+  */
+static int sqlcipher_cipher_ctx_copy(cipher_ctx *target, cipher_ctx *source) {
+  void *key = target->key; 
+  void *hmac_key = target->hmac_key; 
+  void *provider = target->provider;
+  void *provider_ctx = target->provider_ctx;
+
+  CODEC_TRACE(("sqlcipher_cipher_ctx_copy: entered target=%p, source=%p\n", target, source));
+  sqlcipher_free(target->pass, target->pass_sz); 
+  sqlcipher_free(target->keyspec, target->keyspec_sz); 
+  memcpy(target, source, sizeof(cipher_ctx));
+
+  target->key = key; //restore pointer to previously allocated key data
+  memcpy(target->key, source->key, CIPHER_MAX_KEY_SZ);
+
+  target->hmac_key = hmac_key; //restore pointer to previously allocated hmac key data
+  memcpy(target->hmac_key, source->hmac_key, CIPHER_MAX_KEY_SZ);
+
+  target->provider = provider; // restore pointer to previouly allocated provider;
+  memcpy(target->provider, source->provider, sizeof(sqlcipher_provider));
+
+  target->provider_ctx = provider_ctx; // restore pointer to previouly allocated provider context;
+  target->provider->ctx_copy(target->provider_ctx, source->provider_ctx);
+
+  if(source->pass && source->pass_sz) {
+    target->pass = sqlcipher_malloc(source->pass_sz);
+    if(target->pass == NULL) return SQLITE_NOMEM;
+    memcpy(target->pass, source->pass, source->pass_sz);
+  }
+  if(source->keyspec && source->keyspec_sz) {
+    target->keyspec = sqlcipher_malloc(source->keyspec_sz);
+    if(target->keyspec == NULL) return SQLITE_NOMEM;
+    memcpy(target->keyspec, source->keyspec, source->keyspec_sz);
+  }
+  return SQLITE_OK;
+}
+
+/**
+  * Set the keyspec for the cipher_ctx
+  * 
+  * returns SQLITE_OK if assignment was successfull
+  * returns SQLITE_NOMEM if an error occured allocating memory
+  */
+static int sqlcipher_cipher_ctx_set_keyspec(cipher_ctx *ctx, const unsigned char *key, int key_sz, const unsigned char *salt, int salt_sz) {
+
+    /* free, zero existing pointers and size */
+  sqlcipher_free(ctx->keyspec, ctx->keyspec_sz);
+  ctx->keyspec = NULL;
+  ctx->keyspec_sz = 0;
+
+  /* establic a hex-formated key specification, containing the raw encryption key and
+     the salt used to generate it */
+  ctx->keyspec_sz = ((key_sz + salt_sz) * 2) + 3;
+  ctx->keyspec = sqlcipher_malloc(ctx->keyspec_sz);
+  if(ctx->keyspec == NULL) return SQLITE_NOMEM;
+
+  ctx->keyspec[0] = 'x';
+  ctx->keyspec[1] = '\'';
+  cipher_bin2hex(key, key_sz, ctx->keyspec + 2);
+  cipher_bin2hex(salt, salt_sz, ctx->keyspec + (key_sz * 2) + 2);
+  ctx->keyspec[ctx->keyspec_sz - 1] = '\'';
+  return SQLITE_OK;
+}
+
+int sqlcipher_codec_get_store_pass(codec_ctx *ctx) {
+  return ctx->read_ctx->store_pass;
+}
+
+void sqlcipher_codec_set_store_pass(codec_ctx *ctx, int value) {
+  ctx->read_ctx->store_pass = value;
+}
+
+void sqlcipher_codec_get_pass(codec_ctx *ctx, void **zKey, int *nKey) {
+  *zKey = ctx->read_ctx->pass;
+  *nKey = ctx->read_ctx->pass_sz;
+}
+
+/**
+  * Set the passphrase for the cipher_ctx
+  * 
+  * returns SQLITE_OK if assignment was successfull
+  * returns SQLITE_NOMEM if an error occured allocating memory
+  */
+static int sqlcipher_cipher_ctx_set_pass(cipher_ctx *ctx, const void *zKey, int nKey) {
+
+  /* free, zero existing pointers and size */
+  sqlcipher_free(ctx->pass, ctx->pass_sz);
+  ctx->pass = NULL;
+  ctx->pass_sz = 0;
+
+  if(zKey && nKey) { /* if new password is provided, copy it */
+    ctx->pass_sz = nKey;
+    ctx->pass = sqlcipher_malloc(nKey);
+    if(ctx->pass == NULL) return SQLITE_NOMEM;
+    memcpy(ctx->pass, zKey, nKey);
+  } 
+  return SQLITE_OK;
+}
+
+int sqlcipher_codec_ctx_set_pass(codec_ctx *ctx, const void *zKey, int nKey, int for_ctx) {
+  cipher_ctx *c_ctx = for_ctx ? ctx->write_ctx : ctx->read_ctx;
+  int rc;
+
+  if((rc = sqlcipher_cipher_ctx_set_pass(c_ctx, zKey, nKey)) != SQLITE_OK) return rc; 
+  c_ctx->derive_key = 1;
+
+  if(for_ctx == 2)
+    if((rc = sqlcipher_cipher_ctx_copy( for_ctx ? ctx->read_ctx : ctx->write_ctx, c_ctx)) != SQLITE_OK) 
+      return rc; 
+
+  return SQLITE_OK;
+} 
+
+int sqlcipher_codec_ctx_set_cipher(codec_ctx *ctx, const char *cipher_name, int for_ctx) {
+  cipher_ctx *c_ctx = for_ctx ? ctx->write_ctx : ctx->read_ctx;
+  int rc;
+
+  rc = c_ctx->provider->set_cipher(c_ctx->provider_ctx, cipher_name);
+  if(rc != SQLITE_OK){
+    sqlcipher_codec_ctx_set_error(ctx, rc);
+    return rc;
+  }
+  c_ctx->key_sz = c_ctx->provider->get_key_sz(c_ctx->provider_ctx);
+  c_ctx->iv_sz = c_ctx->provider->get_iv_sz(c_ctx->provider_ctx);
+  c_ctx->block_sz = c_ctx->provider->get_block_sz(c_ctx->provider_ctx);
+  c_ctx->hmac_sz = c_ctx->provider->get_hmac_sz(c_ctx->provider_ctx);
+  c_ctx->derive_key = 1;
+
+  if(for_ctx == 2)
+    if((rc = sqlcipher_cipher_ctx_copy( for_ctx ? ctx->read_ctx : ctx->write_ctx, c_ctx)) != SQLITE_OK)
+      return rc; 
+
+  return SQLITE_OK;
+}
+
+const char* sqlcipher_codec_ctx_get_cipher(codec_ctx *ctx, int for_ctx) {
+  cipher_ctx *c_ctx = for_ctx ? ctx->write_ctx : ctx->read_ctx;
+  return c_ctx->provider->get_cipher(c_ctx->provider_ctx);
+}
+
+/* set the global default KDF iteration */
+void sqlcipher_set_default_kdf_iter(int iter) {
+  default_kdf_iter = iter; 
+}
+
+int sqlcipher_get_default_kdf_iter() {
+  return default_kdf_iter;
+}
+
+int sqlcipher_codec_ctx_set_kdf_iter(codec_ctx *ctx, int kdf_iter, int for_ctx) {
+  cipher_ctx *c_ctx = for_ctx ? ctx->write_ctx : ctx->read_ctx;
+  int rc;
+
+  c_ctx->kdf_iter = kdf_iter;
+  c_ctx->derive_key = 1;
+
+  if(for_ctx == 2)
+    if((rc = sqlcipher_cipher_ctx_copy( for_ctx ? ctx->read_ctx : ctx->write_ctx, c_ctx)) != SQLITE_OK)
+      return rc; 
+
+  return SQLITE_OK;
+}
+
+int sqlcipher_codec_ctx_get_kdf_iter(codec_ctx *ctx, int for_ctx) {
+  cipher_ctx *c_ctx = for_ctx ? ctx->write_ctx : ctx->read_ctx;
+  return c_ctx->kdf_iter;
+}
+
+int sqlcipher_codec_ctx_set_fast_kdf_iter(codec_ctx *ctx, int fast_kdf_iter, int for_ctx) {
+  cipher_ctx *c_ctx = for_ctx ? ctx->write_ctx : ctx->read_ctx;
+  int rc;
+
+  c_ctx->fast_kdf_iter = fast_kdf_iter;
+  c_ctx->derive_key = 1;
+
+  if(for_ctx == 2)
+    if((rc = sqlcipher_cipher_ctx_copy( for_ctx ? ctx->read_ctx : ctx->write_ctx, c_ctx)) != SQLITE_OK)
+      return rc; 
+
+  return SQLITE_OK;
+}
+
+int sqlcipher_codec_ctx_get_fast_kdf_iter(codec_ctx *ctx, int for_ctx) {
+  cipher_ctx *c_ctx = for_ctx ? ctx->write_ctx : ctx->read_ctx;
+  return c_ctx->fast_kdf_iter;
+}
+
+/* set the global default flag for HMAC */
+void sqlcipher_set_default_use_hmac(int use) {
+  if(use) default_flags |= CIPHER_FLAG_HMAC; 
+  else default_flags &= ~CIPHER_FLAG_HMAC; 
+}
+
+int sqlcipher_get_default_use_hmac() {
+  return (default_flags & CIPHER_FLAG_HMAC) != 0;
+}
+
+void sqlcipher_set_hmac_salt_mask(unsigned char mask) {
+  hmac_salt_mask = mask;
+}
+
+unsigned char sqlcipher_get_hmac_salt_mask() {
+  return hmac_salt_mask;
+}
+
+/* set the codec flag for whether this individual database should be using hmac */
+int sqlcipher_codec_ctx_set_use_hmac(codec_ctx *ctx, int use) {
+  int reserve = CIPHER_MAX_IV_SZ; /* base reserve size will be IV only */ 
+
+  if(use) reserve += ctx->read_ctx->hmac_sz; /* if reserve will include hmac, update that size */
+
+  /* calculate the amount of reserve needed in even increments of the cipher block size */
+
+  reserve = ((reserve % ctx->read_ctx->block_sz) == 0) ? reserve :
+               ((reserve / ctx->read_ctx->block_sz) + 1) * ctx->read_ctx->block_sz;  
+
+  CODEC_TRACE(("sqlcipher_codec_ctx_set_use_hmac: use=%d block_sz=%d md_size=%d reserve=%d\n", 
+                use, ctx->read_ctx->block_sz, ctx->read_ctx->hmac_sz, reserve)); 
+
+  
+  if(use) {
+    sqlcipher_codec_ctx_set_flag(ctx, CIPHER_FLAG_HMAC);
+  } else {
+    sqlcipher_codec_ctx_unset_flag(ctx, CIPHER_FLAG_HMAC);
+  } 
+  
+  ctx->write_ctx->reserve_sz = ctx->read_ctx->reserve_sz = reserve;
+
+  return SQLITE_OK;
+}
+
+int sqlcipher_codec_ctx_get_use_hmac(codec_ctx *ctx, int for_ctx) {
+  cipher_ctx * c_ctx = for_ctx ? ctx->write_ctx : ctx->read_ctx;
+  return (c_ctx->flags & CIPHER_FLAG_HMAC) != 0;
+}
+
+int sqlcipher_codec_ctx_set_flag(codec_ctx *ctx, unsigned int flag) {
+  ctx->write_ctx->flags |= flag;
+  ctx->read_ctx->flags |= flag;
+  return SQLITE_OK;
+}
+
+int sqlcipher_codec_ctx_unset_flag(codec_ctx *ctx, unsigned int flag) {
+  ctx->write_ctx->flags &= ~flag;
+  ctx->read_ctx->flags &= ~flag;
+  return SQLITE_OK;
+}
+
+int sqlcipher_codec_ctx_get_flag(codec_ctx *ctx, unsigned int flag, int for_ctx) {
+  cipher_ctx * c_ctx = for_ctx ? ctx->write_ctx : ctx->read_ctx;
+  return (c_ctx->flags & flag) != 0;
+}
+
+void sqlcipher_codec_ctx_set_error(codec_ctx *ctx, int error) {
+  CODEC_TRACE(("sqlcipher_codec_ctx_set_error: ctx=%p, error=%d\n", ctx, error));
+  sqlite3pager_sqlite3PagerSetError(ctx->pBt->pBt->pPager, error);
+  ctx->pBt->pBt->db->errCode = error;
+}
+
+int sqlcipher_codec_ctx_get_reservesize(codec_ctx *ctx) {
+  return ctx->read_ctx->reserve_sz;
+}
+
+void* sqlcipher_codec_ctx_get_data(codec_ctx *ctx) {
+  return ctx->buffer;
+}
+
+void* sqlcipher_codec_ctx_get_kdf_salt(codec_ctx *ctx) {
+  return ctx->kdf_salt;
+}
+
+void sqlcipher_codec_get_keyspec(codec_ctx *ctx, void **zKey, int *nKey) {
+  *zKey = ctx->read_ctx->keyspec;
+  *nKey = ctx->read_ctx->keyspec_sz;
+}
+
+int sqlcipher_codec_ctx_set_pagesize(codec_ctx *ctx, int size) {
+  /* attempt to free the existing page buffer */
+  sqlcipher_free(ctx->buffer,ctx->page_sz);
+  ctx->page_sz = size;
+
+  /* pre-allocate a page buffer of PageSize bytes. This will
+     be used as a persistent buffer for encryption and decryption 
+     operations to avoid overhead of multiple memory allocations*/
+  ctx->buffer = sqlcipher_malloc(size);
+  if(ctx->buffer == NULL) return SQLITE_NOMEM;
+
+  return SQLITE_OK;
+}
+
+int sqlcipher_codec_ctx_get_pagesize(codec_ctx *ctx) {
+  return ctx->page_sz;
+}
+
+void sqlcipher_set_default_pagesize(int page_size) {
+  default_page_size = page_size;
+}
+
+int sqlcipher_get_default_pagesize() {
+  return default_page_size;
+}
+
+int sqlcipher_codec_ctx_init(codec_ctx **iCtx, Db *pDb, Pager *pPager, sqlite3_file *fd, const void *zKey, int nKey) {
+  int rc;
+  codec_ctx *ctx;
+  *iCtx = sqlcipher_malloc(sizeof(codec_ctx));
+  ctx = *iCtx;
+
+  if(ctx == NULL) return SQLITE_NOMEM;
+
+  ctx->pBt = pDb->pBt; /* assign pointer to database btree structure */
+
+  /* allocate space for salt data. Then read the first 16 bytes 
+       directly off the database file. This is the salt for the
+       key derivation function. If we get a short read allocate
+       a new random salt value */
+  ctx->kdf_salt_sz = FILE_HEADER_SZ;
+  ctx->kdf_salt = sqlcipher_malloc(ctx->kdf_salt_sz);
+  if(ctx->kdf_salt == NULL) return SQLITE_NOMEM;
+
+  /* allocate space for separate hmac salt data. We want the
+     HMAC derivation salt to be different than the encryption
+     key derivation salt */
+  ctx->hmac_kdf_salt = sqlcipher_malloc(ctx->kdf_salt_sz);
+  if(ctx->hmac_kdf_salt == NULL) return SQLITE_NOMEM;
+
+
+  /*
+     Always overwrite page size and set to the default because the first page of the database
+     in encrypted and thus sqlite can't effectively determine the pagesize. this causes an issue in 
+     cases where bytes 16 & 17 of the page header are a power of 2 as reported by John Lehman
+  */
+  if((rc = sqlcipher_codec_ctx_set_pagesize(ctx, default_page_size)) != SQLITE_OK) return rc;
+
+  if((rc = sqlcipher_cipher_ctx_init(&ctx->read_ctx)) != SQLITE_OK) return rc; 
+  if((rc = sqlcipher_cipher_ctx_init(&ctx->write_ctx)) != SQLITE_OK) return rc; 
+
+  if(fd == NULL || sqlite3OsRead(fd, ctx->kdf_salt, FILE_HEADER_SZ, 0) != SQLITE_OK) {
+    ctx->need_kdf_salt = 1;
+  }
+
+  if((rc = sqlcipher_codec_ctx_set_cipher(ctx, CIPHER, 0)) != SQLITE_OK) return rc;
+  if((rc = sqlcipher_codec_ctx_set_kdf_iter(ctx, default_kdf_iter, 0)) != SQLITE_OK) return rc;
+  if((rc = sqlcipher_codec_ctx_set_fast_kdf_iter(ctx, FAST_PBKDF2_ITER, 0)) != SQLITE_OK) return rc;
+  if((rc = sqlcipher_codec_ctx_set_pass(ctx, zKey, nKey, 0)) != SQLITE_OK) return rc;
+
+  /* Note that use_hmac is a special case that requires recalculation of page size
+     so we call set_use_hmac to perform setup */
+  if((rc = sqlcipher_codec_ctx_set_use_hmac(ctx, default_flags & CIPHER_FLAG_HMAC)) != SQLITE_OK) return rc;
+
+  if((rc = sqlcipher_cipher_ctx_copy(ctx->write_ctx, ctx->read_ctx)) != SQLITE_OK) return rc;
+
+  return SQLITE_OK;
+}
+
+/**
+  * Free and wipe memory associated with a cipher_ctx, including the allocated
+  * read_ctx and write_ctx.
+  */
+void sqlcipher_codec_ctx_free(codec_ctx **iCtx) {
+  codec_ctx *ctx = *iCtx;
+  CODEC_TRACE(("codec_ctx_free: entered iCtx=%p\n", iCtx));
+  sqlcipher_free(ctx->kdf_salt, ctx->kdf_salt_sz);
+  sqlcipher_free(ctx->hmac_kdf_salt, ctx->kdf_salt_sz);
+  sqlcipher_free(ctx->buffer, 0);
+  sqlcipher_cipher_ctx_free(&ctx->read_ctx);
+  sqlcipher_cipher_ctx_free(&ctx->write_ctx);
+  sqlcipher_free(ctx, sizeof(codec_ctx)); 
+}
+
+/** convert a 32bit unsigned integer to little endian byte ordering */
+static void sqlcipher_put4byte_le(unsigned char *p, u32 v) { 
+  p[0] = (u8)v;
+  p[1] = (u8)(v>>8);
+  p[2] = (u8)(v>>16);
+  p[3] = (u8)(v>>24);
+}
+
+static int sqlcipher_page_hmac(cipher_ctx *ctx, Pgno pgno, unsigned char *in, int in_sz, unsigned char *out) {
+  unsigned char pgno_raw[sizeof(pgno)];
+  /* we may convert page number to consistent representation before calculating MAC for
+     compatibility across big-endian and little-endian platforms. 
+
+     Note: The public release of sqlcipher 2.0.0 to 2.0.6 had a bug where the bytes of pgno 
+     were used directly in the MAC. SQLCipher convert's to little endian by default to preserve
+     backwards compatibility on the most popular platforms, but can optionally be configured
+     to use either big endian or native byte ordering via pragma. */
+
+  if(ctx->flags & CIPHER_FLAG_LE_PGNO) { /* compute hmac using little endian pgno*/
+    sqlcipher_put4byte_le(pgno_raw, pgno);
+  } else if(ctx->flags & CIPHER_FLAG_BE_PGNO) { /* compute hmac using big endian pgno */
+    sqlite3Put4byte(pgno_raw, pgno); /* sqlite3Put4byte converts 32bit uint to big endian  */
+  } else { /* use native byte ordering */
+    memcpy(pgno_raw, &pgno, sizeof(pgno));
+  }
+
+  /* include the encrypted page data,  initialization vector, and page number in HMAC. This will 
+     prevent both tampering with the ciphertext, manipulation of the IV, or resequencing otherwise
+     valid pages out of order in a database */ 
+  ctx->provider->hmac(
+    ctx->provider_ctx, ctx->hmac_key,
+    ctx->key_sz, in,
+    in_sz, (unsigned char*) &pgno_raw,
+    sizeof(pgno), out);
+  return SQLITE_OK; 
+}
+
+/*
+ * ctx - codec context
+ * pgno - page number in database
+ * size - size in bytes of input and output buffers
+ * mode - 1 to encrypt, 0 to decrypt
+ * in - pointer to input bytes
+ * out - pouter to output bytes
+ */
+int sqlcipher_page_cipher(codec_ctx *ctx, int for_ctx, Pgno pgno, int mode, int page_sz, unsigned char *in, unsigned char *out) {
+  cipher_ctx *c_ctx = for_ctx ? ctx->write_ctx : ctx->read_ctx;
+  unsigned char *iv_in, *iv_out, *hmac_in, *hmac_out, *out_start;
+  int size;
+
+  /* calculate some required positions into various buffers */
+  size = page_sz - c_ctx->reserve_sz; /* adjust size to useable size and memset reserve at end of page */
+  iv_out = out + size;
+  iv_in = in + size;
+
+  /* hmac will be written immediately after the initialization vector. the remainder of the page reserve will contain
+     random bytes. note, these pointers are only valid when using hmac */
+  hmac_in = in + size + c_ctx->iv_sz; 
+  hmac_out = out + size + c_ctx->iv_sz;
+  out_start = out; /* note the original position of the output buffer pointer, as out will be rewritten during encryption */
+
+  CODEC_TRACE(("codec_cipher:entered pgno=%d, mode=%d, size=%d\n", pgno, mode, size));
+  CODEC_HEXDUMP("codec_cipher: input page data", in, page_sz);
+
+  /* the key size should never be zero. If it is, error out. */
+  if(c_ctx->key_sz == 0) {
+    CODEC_TRACE(("codec_cipher: error possible context corruption, key_sz is zero for pgno=%d\n", pgno));
+    sqlcipher_memset(out, 0, page_sz); 
+    return SQLITE_ERROR;
+  } 
+
+  if(mode == CIPHER_ENCRYPT) {
+    /* start at front of the reserve block, write random data to the end */
+    if(c_ctx->provider->random(c_ctx->provider_ctx, iv_out, c_ctx->reserve_sz) != SQLITE_OK) return SQLITE_ERROR; 
+  } else { /* CIPHER_DECRYPT */
+    memcpy(iv_out, iv_in, c_ctx->iv_sz); /* copy the iv from the input to output buffer */
+  } 
+
+  if((c_ctx->flags & CIPHER_FLAG_HMAC) && (mode == CIPHER_DECRYPT) && !ctx->skip_read_hmac) {
+    if(sqlcipher_page_hmac(c_ctx, pgno, in, size + c_ctx->iv_sz, hmac_out) != SQLITE_OK) {
+      sqlcipher_memset(out, 0, page_sz); 
+      CODEC_TRACE(("codec_cipher: hmac operations failed for pgno=%d\n", pgno));
+      return SQLITE_ERROR;
+    }
+
+    CODEC_TRACE(("codec_cipher: comparing hmac on in=%p out=%p hmac_sz=%d\n", hmac_in, hmac_out, c_ctx->hmac_sz));
+    if(sqlcipher_memcmp(hmac_in, hmac_out, c_ctx->hmac_sz) != 0) { /* the hmac check failed */ 
+      if(sqlcipher_ismemset(in, 0, page_sz) == 0) {
+        /* first check if the entire contents of the page is zeros. If so, this page 
+           resulted from a short read (i.e. sqlite attempted to pull a page after the end of the file. these 
+           short read failures must be ignored for autovaccum mode to work so wipe the output buffer 
+           and return SQLITE_OK to skip the decryption step. */
+        CODEC_TRACE(("codec_cipher: zeroed page (short read) for pgno %d, encryption but returning SQLITE_OK\n", pgno));
+        sqlcipher_memset(out, 0, page_sz); 
+  	return SQLITE_OK;
+      } else {
+	/* if the page memory is not all zeros, it means the there was data and a hmac on the page. 
+           since the check failed, the page was either tampered with or corrupted. wipe the output buffer,
+           and return SQLITE_ERROR to the caller */
+      	CODEC_TRACE(("codec_cipher: hmac check failed for pgno=%d returning SQLITE_ERROR\n", pgno));
+        sqlcipher_memset(out, 0, page_sz); 
+      	return SQLITE_ERROR;
+      }
+    }
+  } 
+  
+  c_ctx->provider->cipher(c_ctx->provider_ctx, mode, c_ctx->key, c_ctx->key_sz, iv_out, in, size, out);
+
+  if((c_ctx->flags & CIPHER_FLAG_HMAC) && (mode == CIPHER_ENCRYPT)) {
+    sqlcipher_page_hmac(c_ctx, pgno, out_start, size + c_ctx->iv_sz, hmac_out); 
+  }
+
+  CODEC_HEXDUMP("codec_cipher: output page data", out_start, page_sz);
+
+  return SQLITE_OK;
+}
+
+/**
+  * Derive an encryption key for a cipher contex key based on the raw password.
+  *
+  * If the raw key data is formated as x'hex' and there are exactly enough hex chars to fill
+  * the key (i.e 64 hex chars for a 256 bit key) then the key data will be used directly. 
+
+  * Else, if the raw key data is formated as x'hex' and there are exactly enough hex chars to fill
+  * the key and the salt (i.e 92 hex chars for a 256 bit key and 16 byte salt) then it will be unpacked
+  * as the key followed by the salt.
+  * 
+  * Otherwise, a key data will be derived using PBKDF2
+  * 
+  * returns SQLITE_OK if initialization was successful
+  * returns SQLITE_ERROR if the key could't be derived (for instance if pass is NULL or pass_sz is 0)
+  */
+static int sqlcipher_cipher_ctx_key_derive(codec_ctx *ctx, cipher_ctx *c_ctx) {
+  int rc;
+  CODEC_TRACE(("cipher_ctx_key_derive: entered c_ctx->pass=%s, c_ctx->pass_sz=%d \
+                ctx->kdf_salt=%p ctx->kdf_salt_sz=%d c_ctx->kdf_iter=%d \
+                ctx->hmac_kdf_salt=%p, c_ctx->fast_kdf_iter=%d c_ctx->key_sz=%d\n", 
+                c_ctx->pass, c_ctx->pass_sz, ctx->kdf_salt, ctx->kdf_salt_sz, c_ctx->kdf_iter, 
+                ctx->hmac_kdf_salt, c_ctx->fast_kdf_iter, c_ctx->key_sz)); 
+                
+  
+  if(c_ctx->pass && c_ctx->pass_sz) { // if pass is not null
+
+    if(ctx->need_kdf_salt) {
+      if(ctx->read_ctx->provider->random(ctx->read_ctx->provider_ctx, ctx->kdf_salt, FILE_HEADER_SZ) != SQLITE_OK) return SQLITE_ERROR;
+      ctx->need_kdf_salt = 0;
+    }
+    if (c_ctx->pass_sz == ((c_ctx->key_sz * 2) + 3) && sqlite3StrNICmp((const char *)c_ctx->pass ,"x'", 2) == 0 && cipher_isHex(c_ctx->pass + 2, c_ctx->key_sz * 2)) { 
+      int n = c_ctx->pass_sz - 3; /* adjust for leading x' and tailing ' */
+      const unsigned char *z = c_ctx->pass + 2; /* adjust lead offset of x' */
+      CODEC_TRACE(("cipher_ctx_key_derive: using raw key from hex\n")); 
+      cipher_hex2bin(z, n, c_ctx->key);
+    } else if (c_ctx->pass_sz == (((c_ctx->key_sz + ctx->kdf_salt_sz) * 2) + 3) && sqlite3StrNICmp((const char *)c_ctx->pass ,"x'", 2) == 0 && cipher_isHex(c_ctx->pass + 2, (c_ctx->key_sz + ctx->kdf_salt_sz) * 2)) { 
+      const unsigned char *z = c_ctx->pass + 2; /* adjust lead offset of x' */
+      CODEC_TRACE(("cipher_ctx_key_derive: using raw key from hex\n")); 
+      cipher_hex2bin(z, (c_ctx->key_sz * 2), c_ctx->key);
+      cipher_hex2bin(z + (c_ctx->key_sz * 2), (ctx->kdf_salt_sz * 2), ctx->kdf_salt);
+    } else { 
+      CODEC_TRACE(("cipher_ctx_key_derive: deriving key using full PBKDF2 with %d iterations\n", c_ctx->kdf_iter)); 
+      c_ctx->provider->kdf(c_ctx->provider_ctx, c_ctx->pass, c_ctx->pass_sz, 
+                    ctx->kdf_salt, ctx->kdf_salt_sz, c_ctx->kdf_iter,
+                    c_ctx->key_sz, c_ctx->key);
+    }
+
+    /* set the context "keyspec" containing the hex-formatted key and salt to be used when attaching databases */
+    if((rc = sqlcipher_cipher_ctx_set_keyspec(c_ctx, c_ctx->key, c_ctx->key_sz, ctx->kdf_salt, ctx->kdf_salt_sz)) != SQLITE_OK) return rc;
+
+    /* if this context is setup to use hmac checks, generate a seperate and different 
+       key for HMAC. In this case, we use the output of the previous KDF as the input to 
+       this KDF run. This ensures a distinct but predictable HMAC key. */
+    if(c_ctx->flags & CIPHER_FLAG_HMAC) {
+      int i;
+
+      /* start by copying the kdf key into the hmac salt slot
+         then XOR it with the fixed hmac salt defined at compile time
+         this ensures that the salt passed in to derive the hmac key, while 
+         easy to derive and publically known, is not the same as the salt used 
+         to generate the encryption key */ 
+      memcpy(ctx->hmac_kdf_salt, ctx->kdf_salt, ctx->kdf_salt_sz);
+      for(i = 0; i < ctx->kdf_salt_sz; i++) {
+        ctx->hmac_kdf_salt[i] ^= hmac_salt_mask;
+      } 
+
+      CODEC_TRACE(("cipher_ctx_key_derive: deriving hmac key from encryption key using PBKDF2 with %d iterations\n", 
+        c_ctx->fast_kdf_iter)); 
+
+      
+      c_ctx->provider->kdf(c_ctx->provider_ctx, c_ctx->key, c_ctx->key_sz, 
+                    ctx->hmac_kdf_salt, ctx->kdf_salt_sz, c_ctx->fast_kdf_iter,
+                    c_ctx->key_sz, c_ctx->hmac_key); 
+    }
+
+    c_ctx->derive_key = 0;
+    return SQLITE_OK;
+  };
+  return SQLITE_ERROR;
+}
+
+int sqlcipher_codec_key_derive(codec_ctx *ctx) {
+  /* derive key on first use if necessary */
+  if(ctx->read_ctx->derive_key) {
+    if(sqlcipher_cipher_ctx_key_derive(ctx, ctx->read_ctx) != SQLITE_OK) return SQLITE_ERROR;
+  }
+
+  if(ctx->write_ctx->derive_key) {
+    if(sqlcipher_cipher_ctx_cmp(ctx->write_ctx, ctx->read_ctx) == 0) {
+      /* the relevant parameters are the same, just copy read key */
+      if(sqlcipher_cipher_ctx_copy(ctx->write_ctx, ctx->read_ctx) != SQLITE_OK) return SQLITE_ERROR;
+    } else {
+      if(sqlcipher_cipher_ctx_key_derive(ctx, ctx->write_ctx) != SQLITE_OK) return SQLITE_ERROR;
+    }
+  }
+
+  /* TODO: wipe and free passphrase after key derivation */
+  if(ctx->read_ctx->store_pass  != 1) {
+    sqlcipher_cipher_ctx_set_pass(ctx->read_ctx, NULL, 0);
+    sqlcipher_cipher_ctx_set_pass(ctx->write_ctx, NULL, 0);
+  }
+
+  return SQLITE_OK; 
+}
+
+int sqlcipher_codec_key_copy(codec_ctx *ctx, int source) {
+  if(source == CIPHER_READ_CTX) { 
+      return sqlcipher_cipher_ctx_copy(ctx->write_ctx, ctx->read_ctx); 
+  } else {
+      return sqlcipher_cipher_ctx_copy(ctx->read_ctx, ctx->write_ctx); 
+  }
+}
+
+const char* sqlcipher_codec_get_cipher_provider(codec_ctx *ctx) {
+  return ctx->read_ctx->provider->get_provider_name(ctx->read_ctx);
+}
+
+
+static int sqlcipher_check_connection(const char *filename, char *key, int key_sz, char *sql, int *user_version) {
+  int rc;
+  sqlite3 *db = NULL;
+  sqlite3_stmt *statement = NULL;
+  char *query_user_version = "PRAGMA user_version;";
+  
+  rc = sqlite3_open(filename, &db);
+  if(rc != SQLITE_OK){
+    goto cleanup;
+  }
+  rc = sqlite3_key(db, key, key_sz);
+  if(rc != SQLITE_OK){
+    goto cleanup;
+  }
+  rc = sqlite3_exec(db, sql, NULL, NULL, NULL);
+  if(rc != SQLITE_OK){
+    goto cleanup;
+  }
+  rc = sqlite3_prepare(db, query_user_version, -1, &statement, NULL);
+  if(rc != SQLITE_OK){
+    goto cleanup;
+  }
+  rc = sqlite3_step(statement);
+  if(rc == SQLITE_ROW){
+    *user_version = sqlite3_column_int(statement, 0);
+    rc = SQLITE_OK;
+  }
+  
+cleanup:
+  if(statement){
+    sqlite3_finalize(statement);
+  }
+  if(db){
+    sqlite3_close(db);
+  }
+  return rc;
+}
+
+int sqlcipher_codec_ctx_migrate(codec_ctx *ctx) {
+  u32 meta;
+  int rc = 0;
+  int command_idx = 0;
+  int password_sz;
+  int saved_flags;
+  int saved_nChange;
+  int saved_nTotalChange;
+  int (*saved_xTrace)(u32,void*,void*,void*); /* Saved db->xTrace */
+  Db *pDb = 0;
+  sqlite3 *db = ctx->pBt->db;
+  const char *db_filename = sqlite3_db_filename(db, "main");
+  char *migrated_db_filename = sqlite3_mprintf("%s-migrated", db_filename);
+  char *pragma_hmac_off = "PRAGMA cipher_use_hmac = OFF;";
+  char *pragma_4k_kdf_iter = "PRAGMA kdf_iter = 4000;";
+  char *pragma_1x_and_4k;
+  char *set_user_version;
+  char *key;
+  int key_sz;
+  int user_version = 0;
+  int upgrade_1x_format = 0;
+  int upgrade_4k_format = 0;
+  static const unsigned char aCopy[] = {
+    BTREE_SCHEMA_VERSION,     1,  /* Add one to the old schema cookie */
+    BTREE_DEFAULT_CACHE_SIZE, 0,  /* Preserve the default page cache size */
+    BTREE_TEXT_ENCODING,      0,  /* Preserve the text encoding */
+    BTREE_USER_VERSION,       0,  /* Preserve the user version */
+    BTREE_APPLICATION_ID,     0,  /* Preserve the application id */
+  };
+
+
+  key_sz = ctx->read_ctx->pass_sz + 1;
+  key = sqlcipher_malloc(key_sz);
+  memset(key, 0, key_sz);
+  memcpy(key, ctx->read_ctx->pass, ctx->read_ctx->pass_sz);
+
+  if(db_filename){
+    const char* commands[5];
+    char *attach_command = sqlite3_mprintf("ATTACH DATABASE '%s-migrated' as migrate KEY '%q';",
+                                            db_filename, key);
+
+    int rc = sqlcipher_check_connection(db_filename, key, ctx->read_ctx->pass_sz, "", &user_version);
+    if(rc == SQLITE_OK){
+      CODEC_TRACE(("No upgrade required - exiting\n"));
+      goto exit;
+    }
+    
+    // Version 2 - check for 4k with hmac format 
+    rc = sqlcipher_check_connection(db_filename, key, ctx->read_ctx->pass_sz, pragma_4k_kdf_iter, &user_version);
+    if(rc == SQLITE_OK) {
+      CODEC_TRACE(("Version 2 format found\n"));
+      upgrade_4k_format = 1;
+    }
+
+    // Version 1 - check both no hmac and 4k together
+    pragma_1x_and_4k = sqlite3_mprintf("%s%s", pragma_hmac_off,
+                                             pragma_4k_kdf_iter);
+    rc = sqlcipher_check_connection(db_filename, key, ctx->read_ctx->pass_sz, pragma_1x_and_4k, &user_version);
+    sqlite3_free(pragma_1x_and_4k);
+    if(rc == SQLITE_OK) {
+      CODEC_TRACE(("Version 1 format found\n"));
+      upgrade_1x_format = 1;
+      upgrade_4k_format = 1;
+    }
+
+    if(upgrade_1x_format == 0 && upgrade_4k_format == 0) {
+      CODEC_TRACE(("Upgrade format not determined\n"));
+      goto handle_error;
+    }
+
+    set_user_version = sqlite3_mprintf("PRAGMA migrate.user_version = %d;", user_version);
+    commands[0] = upgrade_4k_format == 1 ? pragma_4k_kdf_iter : "";
+    commands[1] = upgrade_1x_format == 1 ? pragma_hmac_off : "";
+    commands[2] = attach_command;
+    commands[3] = "SELECT sqlcipher_export('migrate');";
+    commands[4] = set_user_version;
+      
+    for(command_idx = 0; command_idx < ArraySize(commands); command_idx++){
+      const char *command = commands[command_idx];
+      if(strcmp(command, "") == 0){
+        continue;
+      }
+      rc = sqlite3_exec(db, command, NULL, NULL, NULL);
+      if(rc != SQLITE_OK){
+        break;
+      }
+    }
+    sqlite3_free(attach_command);
+    sqlite3_free(set_user_version);
+    sqlcipher_free(key, key_sz);
+    
+    if(rc == SQLITE_OK){
+      Btree *pDest;
+      Btree *pSrc;
+      int i = 0;
+
+      if( !db->autoCommit ){
+        CODEC_TRACE(("cannot migrate from within a transaction"));
+        goto handle_error;
+      }
+      if( db->nVdbeActive>1 ){
+        CODEC_TRACE(("cannot migrate - SQL statements in progress"));
+        goto handle_error;
+      }
+
+      /* Save the current value of the database flags so that it can be
+      ** restored before returning. Then set the writable-schema flag, and
+      ** disable CHECK and foreign key constraints.  */
+      saved_flags = db->flags;
+      saved_nChange = db->nChange;
+      saved_nTotalChange = db->nTotalChange;
+      saved_xTrace = db->xTrace;
+      db->flags |= SQLITE_WriteSchema | SQLITE_IgnoreChecks | SQLITE_PreferBuiltin;
+      db->flags &= ~(SQLITE_ForeignKeys | SQLITE_ReverseOrder);
+      db->xTrace = 0;
+      
+      pDest = db->aDb[0].pBt;
+      pDb = &(db->aDb[db->nDb-1]);
+      pSrc = pDb->pBt;
+      
+      rc = sqlite3_exec(db, "BEGIN;", NULL, NULL, NULL);
+      rc = sqlite3BtreeBeginTrans(pSrc, 2);
+      rc = sqlite3BtreeBeginTrans(pDest, 2);
+      
+      assert( 1==sqlite3BtreeIsInTrans(pDest) );
+      assert( 1==sqlite3BtreeIsInTrans(pSrc) );
+
+      sqlite3CodecGetKey(db, db->nDb - 1, (void**)&key, &password_sz);
+      sqlite3CodecAttach(db, 0, key, password_sz);
+      sqlite3pager_get_codec(pDest->pBt->pPager, (void**)&ctx);
+      
+      ctx->skip_read_hmac = 1;      
+      for(i=0; i<ArraySize(aCopy); i+=2){
+        sqlite3BtreeGetMeta(pSrc, aCopy[i], &meta);
+        rc = sqlite3BtreeUpdateMeta(pDest, aCopy[i], meta+aCopy[i+1]);
+        if( NEVER(rc!=SQLITE_OK) ) goto handle_error; 
+      }
+      rc = sqlite3BtreeCopyFile(pDest, pSrc);
+      ctx->skip_read_hmac = 0;
+      if( rc!=SQLITE_OK ) goto handle_error;
+      rc = sqlite3BtreeCommit(pDest);
+
+      db->flags = saved_flags;
+      db->nChange = saved_nChange;
+      db->nTotalChange = saved_nTotalChange;
+      db->xTrace = saved_xTrace;
+      db->autoCommit = 1;
+      sqlite3BtreeClose(pDb->pBt);
+      pDb->pBt = 0;
+      pDb->pSchema = 0;
+      sqlite3ResetAllSchemasOfConnection(db);
+      remove(migrated_db_filename);
+      sqlite3_free(migrated_db_filename);
+    } else {
+      CODEC_TRACE(("*** migration failure** \n\n"));
+    }
+    
+  }
+  goto exit;
+
+ handle_error:
+  CODEC_TRACE(("An error occurred attempting to migrate the database\n"));
+  rc = SQLITE_ERROR;
+
+ exit:
+  return rc;
+}
+
+int sqlcipher_codec_add_random(codec_ctx *ctx, const char *zRight, int random_sz){
+  const char *suffix = &zRight[random_sz-1];
+  int n = random_sz - 3; /* adjust for leading x' and tailing ' */
+  if (n > 0 &&
+      sqlite3StrNICmp((const char *)zRight ,"x'", 2) == 0 &&
+      sqlite3StrNICmp(suffix, "'", 1) == 0 &&
+      n % 2 == 0) {
+    int rc = 0;
+    int buffer_sz = n / 2;
+    unsigned char *random;
+    const unsigned char *z = (const unsigned char *)zRight + 2; /* adjust lead offset of x' */
+    CODEC_TRACE(("sqlcipher_codec_add_random: using raw random blob from hex\n"));
+    random = sqlcipher_malloc(buffer_sz);
+    memset(random, 0, buffer_sz);
+    cipher_hex2bin(z, n, random);
+    rc = ctx->read_ctx->provider->add_random(ctx->read_ctx->provider_ctx, random, buffer_sz);
+    sqlcipher_free(random, buffer_sz);
+    return rc;
+  }
+  return SQLITE_ERROR;
+}
+
+int sqlcipher_cipher_profile(sqlite3 *db, const char *destination){
+  FILE *f;
+  if(sqlite3StrICmp(destination, "stdout") == 0){
+    f = stdout;
+  }else if(sqlite3StrICmp(destination, "stderr") == 0){
+    f = stderr;
+  }else if(sqlite3StrICmp(destination, "off") == 0){
+    f = 0;
+  }else{
+#if defined(_WIN32) && (__STDC_VERSION__ > 199901L) || defined(SQLITE_OS_WINRT)
+    if(fopen_s(&f, destination, "a") != 0){
+#else
+    f = fopen(destination, "a");
+    if(f == 0){
+#endif    
+    return SQLITE_ERROR;
+  }	
+
+  }
+  sqlite3_profile(db, sqlcipher_profile_callback, f);
+  return SQLITE_OK;
+}
+
+static void sqlcipher_profile_callback(void *file, const char *sql, sqlite3_uint64 run_time){
+  FILE *f = (FILE*)file;
+  double elapsed = run_time/1000000.0;
+  if(f) fprintf(f, "Elapsed time:%.3f ms - %s\n", elapsed, sql);
+}
+
+int sqlcipher_codec_fips_status(codec_ctx *ctx) {
+  return ctx->read_ctx->provider->fips_status(ctx->read_ctx);
+}
+
+const char* sqlcipher_codec_get_provider_version(codec_ctx *ctx) {
+  return ctx->read_ctx->provider->get_provider_version(ctx->read_ctx);
+}
+
+#endif
+/* END SQLCIPHER */
+
+/************** End of crypto_impl.c *****************************************/
+/************** Begin file crypto_libtomcrypt.c ******************************/
+/*
+** SQLCipher
+** http://sqlcipher.net
+**
+** Copyright (c) 2008 - 2013, ZETETIC LLC
+** All rights reserved.
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are met:
+**     * Redistributions of source code must retain the above copyright
+**       notice, this list of conditions and the following disclaimer.
+**     * Redistributions in binary form must reproduce the above copyright
+**       notice, this list of conditions and the following disclaimer in the
+**       documentation and/or other materials provided with the distribution.
+**     * Neither the name of the ZETETIC LLC nor the
+**       names of its contributors may be used to endorse or promote products
+**       derived from this software without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED BY ZETETIC LLC ''AS IS'' AND ANY
+** EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+** WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+** DISCLAIMED. IN NO EVENT SHALL ZETETIC LLC BE LIABLE FOR ANY
+** DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+** (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+** SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+**
+*/
+/* BEGIN SQLCIPHER */
+#ifdef SQLITE_HAS_CODEC
+#ifdef SQLCIPHER_CRYPTO_LIBTOMCRYPT
+/* #include "sqliteInt.h" */
+/* #include "sqlcipher.h" */
+#include <tomcrypt.h>
+
+#define FORTUNA_MAX_SZ 32
+static prng_state prng;
+static unsigned int ltc_init = 0;
+static unsigned int ltc_ref_count = 0;
+static sqlite3_mutex* ltc_rand_mutex = NULL;
+
+static int sqlcipher_ltc_add_random(void *ctx, void *buffer, int length) {
+  int rc = 0;
+  int data_to_read = length;
+  int block_sz = data_to_read < FORTUNA_MAX_SZ ? data_to_read : FORTUNA_MAX_SZ;
+  const unsigned char * data = (const unsigned char *)buffer;
+#ifndef SQLCIPHER_LTC_NO_MUTEX_RAND
+  sqlite3_mutex_enter(ltc_rand_mutex);
+#endif
+    while(data_to_read > 0){
+      rc = fortuna_add_entropy(data, block_sz, &prng);
+      rc = rc != CRYPT_OK ? SQLITE_ERROR : SQLITE_OK;
+      if(rc != SQLITE_OK){
+        break;
+      }
+      data_to_read -= block_sz;
+      data += block_sz;
+      block_sz = data_to_read < FORTUNA_MAX_SZ ? data_to_read : FORTUNA_MAX_SZ;
+    }
+    fortuna_ready(&prng);
+#ifndef SQLCIPHER_LTC_NO_MUTEX_RAND
+  sqlite3_mutex_leave(ltc_rand_mutex);
+#endif
+  return rc;
+}
+
+static int sqlcipher_ltc_activate(void *ctx) {
+  unsigned char random_buffer[FORTUNA_MAX_SZ];
+#ifndef SQLCIPHER_LTC_NO_MUTEX_RAND
+  if(ltc_rand_mutex == NULL){
+    ltc_rand_mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
+  }
+  sqlite3_mutex_enter(ltc_rand_mutex);
+#endif
+  sqlcipher_memset(random_buffer, 0, FORTUNA_MAX_SZ);
+  if(ltc_init == 0) {
+    if(register_prng(&fortuna_desc) != CRYPT_OK) return SQLITE_ERROR;
+    if(register_cipher(&rijndael_desc) != CRYPT_OK) return SQLITE_ERROR;
+    if(register_hash(&sha1_desc) != CRYPT_OK) return SQLITE_ERROR;
+    if(fortuna_start(&prng) != CRYPT_OK) {
+      return SQLITE_ERROR;
+    }
+    ltc_init = 1;
+  }
+  ltc_ref_count++;
+#ifndef SQLCIPHER_TEST
+  sqlite3_randomness(FORTUNA_MAX_SZ, random_buffer);
+#endif
+#ifndef SQLCIPHER_LTC_NO_MUTEX_RAND
+  sqlite3_mutex_leave(ltc_rand_mutex);
+#endif
+  if(sqlcipher_ltc_add_random(ctx, random_buffer, FORTUNA_MAX_SZ) != SQLITE_OK) {
+    return SQLITE_ERROR;
+  }
+  sqlcipher_memset(random_buffer, 0, FORTUNA_MAX_SZ);
+  return SQLITE_OK;
+}
+
+static int sqlcipher_ltc_deactivate(void *ctx) {
+#ifndef SQLCIPHER_LTC_NO_MUTEX_RAND
+  sqlite3_mutex_enter(ltc_rand_mutex);
+#endif
+  ltc_ref_count--;
+  if(ltc_ref_count == 0){
+    fortuna_done(&prng);
+    sqlcipher_memset((void *)&prng, 0, sizeof(prng));
+#ifndef SQLCIPHER_LTC_NO_MUTEX_RAND
+    sqlite3_mutex_leave(ltc_rand_mutex);
+    sqlite3_mutex_free(ltc_rand_mutex);
+    ltc_rand_mutex = NULL;
+#endif
+  }
+#ifndef SQLCIPHER_LTC_NO_MUTEX_RAND
+  else {
+    sqlite3_mutex_leave(ltc_rand_mutex);
+  }
+#endif    
+  return SQLITE_OK;
+}
+
+static const char* sqlcipher_ltc_get_provider_name(void *ctx) {
+  return "libtomcrypt";
+}
+
+static const char* sqlcipher_ltc_get_provider_version(void *ctx) {
+  return SCRYPT;
+}
+
+static int sqlcipher_ltc_random(void *ctx, void *buffer, int length) {
+#ifndef SQLCIPHER_LTC_NO_MUTEX_RAND
+  sqlite3_mutex_enter(ltc_rand_mutex);
+#endif
+  fortuna_read(buffer, length, &prng);
+#ifndef SQLCIPHER_LTC_NO_MUTEX_RAND
+  sqlite3_mutex_leave(ltc_rand_mutex);
+#endif
+  return SQLITE_OK;
+}
+
+static int sqlcipher_ltc_hmac(void *ctx, unsigned char *hmac_key, int key_sz, unsigned char *in, int in_sz, unsigned char *in2, int in2_sz, unsigned char *out) {
+  int rc, hash_idx;
+  hmac_state hmac;
+  unsigned long outlen = key_sz;
+
+  hash_idx = find_hash("sha1");
+  if((rc = hmac_init(&hmac, hash_idx, hmac_key, key_sz)) != CRYPT_OK) return SQLITE_ERROR;
+  if((rc = hmac_process(&hmac, in, in_sz)) != CRYPT_OK) return SQLITE_ERROR;
+  if((rc = hmac_process(&hmac, in2, in2_sz)) != CRYPT_OK) return SQLITE_ERROR;
+  if((rc = hmac_done(&hmac, out, &outlen)) != CRYPT_OK) return SQLITE_ERROR;
+  return SQLITE_OK;
+}
+
+static int sqlcipher_ltc_kdf(void *ctx, const unsigned char *pass, int pass_sz, unsigned char* salt, int salt_sz, int workfactor, int key_sz, unsigned char *key) {
+  int rc, hash_idx;
+  unsigned long outlen = key_sz;
+  unsigned long random_buffer_sz = sizeof(char) * 256;
+  unsigned char *random_buffer = sqlcipher_malloc(random_buffer_sz);
+  sqlcipher_memset(random_buffer, 0, random_buffer_sz);
+
+  hash_idx = find_hash("sha1");
+  if((rc = pkcs_5_alg2(pass, pass_sz, salt, salt_sz,
+                       workfactor, hash_idx, key, &outlen)) != CRYPT_OK) {
+    return SQLITE_ERROR;
+  }
+  if((rc = pkcs_5_alg2(key, key_sz, salt, salt_sz,
+                       1, hash_idx, random_buffer, &random_buffer_sz)) != CRYPT_OK) {
+    return SQLITE_ERROR;
+  }
+  sqlcipher_ltc_add_random(ctx, random_buffer, random_buffer_sz);
+  sqlcipher_free(random_buffer, random_buffer_sz);
+  return SQLITE_OK;
+}
+
+static const char* sqlcipher_ltc_get_cipher(void *ctx) {
+  return "rijndael";
+}
+
+static int sqlcipher_ltc_cipher(void *ctx, int mode, unsigned char *key, int key_sz, unsigned char *iv, unsigned char *in, int in_sz, unsigned char *out) {
+  int rc, cipher_idx;
+  symmetric_CBC cbc;
+
+  if((cipher_idx = find_cipher(sqlcipher_ltc_get_cipher(ctx))) == -1) return SQLITE_ERROR;
+  if((rc = cbc_start(cipher_idx, iv, key, key_sz, 0, &cbc)) != CRYPT_OK) return SQLITE_ERROR;
+  rc = mode == 1 ? cbc_encrypt(in, out, in_sz, &cbc) : cbc_decrypt(in, out, in_sz, &cbc);
+  if(rc != CRYPT_OK) return SQLITE_ERROR;
+  cbc_done(&cbc);
+  return SQLITE_OK;
+}
+
+static int sqlcipher_ltc_set_cipher(void *ctx, const char *cipher_name) {
+  return SQLITE_OK;
+}
+
+static int sqlcipher_ltc_get_key_sz(void *ctx) {
+  int cipher_idx = find_cipher(sqlcipher_ltc_get_cipher(ctx));
+  return cipher_descriptor[cipher_idx].max_key_length;
+}
+
+static int sqlcipher_ltc_get_iv_sz(void *ctx) {
+  int cipher_idx = find_cipher(sqlcipher_ltc_get_cipher(ctx));
+  return cipher_descriptor[cipher_idx].block_length;
+}
+
+static int sqlcipher_ltc_get_block_sz(void *ctx) {
+  int cipher_idx = find_cipher(sqlcipher_ltc_get_cipher(ctx));
+  return cipher_descriptor[cipher_idx].block_length;
+}
+
+static int sqlcipher_ltc_get_hmac_sz(void *ctx) {
+  int hash_idx = find_hash("sha1");
+  return hash_descriptor[hash_idx].hashsize;
+}
+
+static int sqlcipher_ltc_ctx_copy(void *target_ctx, void *source_ctx) {
+  return SQLITE_OK;
+}
+
+static int sqlcipher_ltc_ctx_cmp(void *c1, void *c2) {
+  return 1;
+}
+
+static int sqlcipher_ltc_ctx_init(void **ctx) {
+  sqlcipher_ltc_activate(NULL);
+  return SQLITE_OK;
+}
+
+static int sqlcipher_ltc_ctx_free(void **ctx) {
+  sqlcipher_ltc_deactivate(&ctx);
+  return SQLITE_OK;
+}
+
+static int sqlcipher_ltc_fips_status(void *ctx) {
+  return 0;
+}
+
+int sqlcipher_ltc_setup(sqlcipher_provider *p) {
+  p->activate = sqlcipher_ltc_activate;
+  p->deactivate = sqlcipher_ltc_deactivate;
+  p->get_provider_name = sqlcipher_ltc_get_provider_name;
+  p->random = sqlcipher_ltc_random;
+  p->hmac = sqlcipher_ltc_hmac;
+  p->kdf = sqlcipher_ltc_kdf;
+  p->cipher = sqlcipher_ltc_cipher;
+  p->set_cipher = sqlcipher_ltc_set_cipher;
+  p->get_cipher = sqlcipher_ltc_get_cipher;
+  p->get_key_sz = sqlcipher_ltc_get_key_sz;
+  p->get_iv_sz = sqlcipher_ltc_get_iv_sz;
+  p->get_block_sz = sqlcipher_ltc_get_block_sz;
+  p->get_hmac_sz = sqlcipher_ltc_get_hmac_sz;
+  p->ctx_copy = sqlcipher_ltc_ctx_copy;
+  p->ctx_cmp = sqlcipher_ltc_ctx_cmp;
+  p->ctx_init = sqlcipher_ltc_ctx_init;
+  p->ctx_free = sqlcipher_ltc_ctx_free;
+  p->add_random = sqlcipher_ltc_add_random;
+  p->fips_status = sqlcipher_ltc_fips_status;
+  p->get_provider_version = sqlcipher_ltc_get_provider_version;
+  return SQLITE_OK;
+}
+
+#endif
+#endif
+/* END SQLCIPHER */
+
+/************** End of crypto_libtomcrypt.c **********************************/
+/************** Begin file crypto_openssl.c **********************************/
+/*
+** SQLCipher
+** http://sqlcipher.net
+**
+** Copyright (c) 2008 - 2013, ZETETIC LLC
+** All rights reserved.
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are met:
+**     * Redistributions of source code must retain the above copyright
+**       notice, this list of conditions and the following disclaimer.
+**     * Redistributions in binary form must reproduce the above copyright
+**       notice, this list of conditions and the following disclaimer in the
+**       documentation and/or other materials provided with the distribution.
+**     * Neither the name of the ZETETIC LLC nor the
+**       names of its contributors may be used to endorse or promote products
+**       derived from this software without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED BY ZETETIC LLC ''AS IS'' AND ANY
+** EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+** WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+** DISCLAIMED. IN NO EVENT SHALL ZETETIC LLC BE LIABLE FOR ANY
+** DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+** (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+** SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+**
+*/
+/* BEGIN SQLCIPHER */
+#ifdef SQLITE_HAS_CODEC
+#ifdef SQLCIPHER_CRYPTO_OPENSSL
+/* #include "sqliteInt.h" */
+/* #include "crypto.h" */
+/* #include "sqlcipher.h" */
+#include <openssl/rand.h>
+#include <openssl/evp.h>
+#include <openssl/hmac.h>
+
+typedef struct {
+  EVP_CIPHER *evp_cipher;
+} openssl_ctx;
+
+static unsigned int openssl_external_init = 0;
+static unsigned int openssl_init_count = 0;
+static sqlite3_mutex* openssl_rand_mutex = NULL;
+
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
+static HMAC_CTX *HMAC_CTX_new(void)
+{
+  HMAC_CTX *ctx = OPENSSL_malloc(sizeof(*ctx));
+  if (ctx != NULL) {
+    HMAC_CTX_init(ctx);
+  }
+  return ctx;
+}
+
+// Per 1.1.0 (https://wiki.openssl.org/index.php/1.1_API_Changes)
+// HMAC_CTX_free should call HMAC_CTX_cleanup, then EVP_MD_CTX_Cleanup.
+// HMAC_CTX_cleanup internally calls EVP_MD_CTX_cleanup so these
+// calls are not needed.
+static void HMAC_CTX_free(HMAC_CTX *ctx)
+{
+  if (ctx != NULL) {
+    HMAC_CTX_cleanup(ctx);
+    OPENSSL_free(ctx);
+  }
+}
+#endif
+
+static int sqlcipher_openssl_add_random(void *ctx, void *buffer, int length) {
+#ifndef SQLCIPHER_OPENSSL_NO_MUTEX_RAND
+  sqlite3_mutex_enter(openssl_rand_mutex);
+#endif
+  RAND_add(buffer, length, 0);
+#ifndef SQLCIPHER_OPENSSL_NO_MUTEX_RAND
+  sqlite3_mutex_leave(openssl_rand_mutex);
+#endif
+  return SQLITE_OK;
+}
+
+/* activate and initialize sqlcipher. Most importantly, this will automatically
+   intialize OpenSSL's EVP system if it hasn't already be externally. Note that 
+   this function may be called multiple times as new codecs are intiialized. 
+   Thus it performs some basic counting to ensure that only the last and final
+   sqlcipher_openssl_deactivate() will free the EVP structures. 
+*/
+static int sqlcipher_openssl_activate(void *ctx) {
+  /* initialize openssl and increment the internal init counter
+     but only if it hasn't been initalized outside of SQLCipher by this program 
+     e.g. on startup */
+  sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
+
+  if(openssl_init_count == 0 && EVP_get_cipherbyname(CIPHER) != NULL) {
+    /* if openssl has not yet been initialized by this library, but 
+       a call to get_cipherbyname works, then the openssl library
+       has been initialized externally already. */
+    openssl_external_init = 1;
+  }
+
+#ifdef SQLCIPHER_FIPS
+  if(!FIPS_mode()){
+    if(!FIPS_mode_set(1)){
+      ERR_load_crypto_strings();
+      ERR_print_errors_fp(stderr);
+    }
+  }
+#endif
+
+  if(openssl_init_count == 0 && openssl_external_init == 0)  {
+    /* if the library was not externally initialized, then should be now */
+    OpenSSL_add_all_algorithms();
+  } 
+
+#ifndef SQLCIPHER_OPENSSL_NO_MUTEX_RAND
+  if(openssl_rand_mutex == NULL) {
+    /* allocate a mutex to guard against concurrent calls to RAND_bytes() */
+    openssl_rand_mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
+  }
+#endif
+
+  openssl_init_count++; 
+  sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
+  return SQLITE_OK;
+}
+
+/* deactivate SQLCipher, most imporantly decremeting the activation count and
+   freeing the EVP structures on the final deactivation to ensure that 
+   OpenSSL memory is cleaned up */
+static int sqlcipher_openssl_deactivate(void *ctx) {
+  sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
+  openssl_init_count--;
+
+  if(openssl_init_count == 0) {
+    if(openssl_external_init == 0) {
+    /* if OpenSSL hasn't be initialized externally, and the counter reaches zero 
+       after it's decremented, release EVP memory
+       Note: this code will only be reached if OpensSSL_add_all_algorithms()
+       is called by SQLCipher internally. This should prevent SQLCipher from 
+       "cleaning up" openssl when it was initialized externally by the program */
+      EVP_cleanup();
+    } else {
+      openssl_external_init = 0;
+    }
+#ifndef SQLCIPHER_OPENSSL_NO_MUTEX_RAND
+    sqlite3_mutex_free(openssl_rand_mutex);
+    openssl_rand_mutex = NULL;
+#endif
+  }
+  sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER));
+  return SQLITE_OK;
+}
+
+static const char* sqlcipher_openssl_get_provider_name(void *ctx) {
+  return "openssl";
+}
+
+static const char* sqlcipher_openssl_get_provider_version(void *ctx) {
+  return OPENSSL_VERSION_TEXT;
+}
+
+/* generate a defined number of random bytes */
+static int sqlcipher_openssl_random (void *ctx, void *buffer, int length) {
+  int rc = 0;
+  /* concurrent calls to RAND_bytes can cause a crash under some openssl versions when a 
+     naive application doesn't use CRYPTO_set_locking_callback and
+     CRYPTO_THREADID_set_callback to ensure openssl thread safety. 
+     This is simple workaround to prevent this common crash
+     but a more proper solution is that applications setup platform-appropriate
+     thread saftey in openssl externally */
+#ifndef SQLCIPHER_OPENSSL_NO_MUTEX_RAND
+  sqlite3_mutex_enter(openssl_rand_mutex);
+#endif
+  rc = RAND_bytes((unsigned char *)buffer, length);
+#ifndef SQLCIPHER_OPENSSL_NO_MUTEX_RAND
+  sqlite3_mutex_leave(openssl_rand_mutex);
+#endif
+  return (rc == 1) ? SQLITE_OK : SQLITE_ERROR;
+}
+
+static int sqlcipher_openssl_hmac(void *ctx, unsigned char *hmac_key, int key_sz, unsigned char *in, int in_sz, unsigned char *in2, int in2_sz, unsigned char *out) {
+  unsigned int outlen;
+  HMAC_CTX* hctx = HMAC_CTX_new();
+  if(hctx == NULL) return SQLITE_ERROR;
+  HMAC_Init_ex(hctx, hmac_key, key_sz, EVP_sha1(), NULL);
+  HMAC_Update(hctx, in, in_sz);
+  HMAC_Update(hctx, in2, in2_sz);
+  HMAC_Final(hctx, out, &outlen);
+  HMAC_CTX_free(hctx);
+  return SQLITE_OK; 
+}
+
+static int sqlcipher_openssl_kdf(void *ctx, const unsigned char *pass, int pass_sz, unsigned char* salt, int salt_sz, int workfactor, int key_sz, unsigned char *key) {
+  PKCS5_PBKDF2_HMAC_SHA1((const char *)pass, pass_sz, salt, salt_sz, workfactor, key_sz, key);
+  return SQLITE_OK; 
+}
+
+static int sqlcipher_openssl_cipher(void *ctx, int mode, unsigned char *key, int key_sz, unsigned char *iv, unsigned char *in, int in_sz, unsigned char *out) {
+  int tmp_csz, csz;
+  EVP_CIPHER_CTX* ectx = EVP_CIPHER_CTX_new();
+  if(ectx == NULL) return SQLITE_ERROR;
+  EVP_CipherInit_ex(ectx, ((openssl_ctx *)ctx)->evp_cipher, NULL, NULL, NULL, mode);
+  EVP_CIPHER_CTX_set_padding(ectx, 0); // no padding
+  EVP_CipherInit_ex(ectx, NULL, NULL, key, iv, mode);
+  EVP_CipherUpdate(ectx, out, &tmp_csz, in, in_sz);
+  csz = tmp_csz;  
+  out += tmp_csz;
+  EVP_CipherFinal_ex(ectx, out, &tmp_csz);
+  csz += tmp_csz;
+  EVP_CIPHER_CTX_free(ectx);
+  assert(in_sz == csz);
+  return SQLITE_OK; 
+}
+
+static int sqlcipher_openssl_set_cipher(void *ctx, const char *cipher_name) {
+  openssl_ctx *o_ctx = (openssl_ctx *)ctx;
+  EVP_CIPHER* cipher = (EVP_CIPHER *) EVP_get_cipherbyname(cipher_name);
+  if(cipher != NULL) {
+    o_ctx->evp_cipher = cipher;
+  }
+  return cipher != NULL ? SQLITE_OK : SQLITE_ERROR;
+}
+
+static const char* sqlcipher_openssl_get_cipher(void *ctx) {
+  return EVP_CIPHER_name(((openssl_ctx *)ctx)->evp_cipher);
+}
+
+static int sqlcipher_openssl_get_key_sz(void *ctx) {
+  return EVP_CIPHER_key_length(((openssl_ctx *)ctx)->evp_cipher);
+}
+
+static int sqlcipher_openssl_get_iv_sz(void *ctx) {
+  return EVP_CIPHER_iv_length(((openssl_ctx *)ctx)->evp_cipher);
+}
+
+static int sqlcipher_openssl_get_block_sz(void *ctx) {
+  return EVP_CIPHER_block_size(((openssl_ctx *)ctx)->evp_cipher);
+}
+
+static int sqlcipher_openssl_get_hmac_sz(void *ctx) {
+  return EVP_MD_size(EVP_sha1());
+}
+
+static int sqlcipher_openssl_ctx_copy(void *target_ctx, void *source_ctx) {
+  memcpy(target_ctx, source_ctx, sizeof(openssl_ctx));
+  return SQLITE_OK;
+}
+
+static int sqlcipher_openssl_ctx_cmp(void *c1, void *c2) {
+  return ((openssl_ctx *)c1)->evp_cipher == ((openssl_ctx *)c2)->evp_cipher;
+}
+
+static int sqlcipher_openssl_ctx_init(void **ctx) {
+  *ctx = sqlcipher_malloc(sizeof(openssl_ctx));
+  if(*ctx == NULL) return SQLITE_NOMEM;
+  sqlcipher_openssl_activate(*ctx);
+  return SQLITE_OK;
+}
+
+static int sqlcipher_openssl_ctx_free(void **ctx) {
+  sqlcipher_openssl_deactivate(*ctx);
+  sqlcipher_free(*ctx, sizeof(openssl_ctx));
+  return SQLITE_OK;
+}
+
+static int sqlcipher_openssl_fips_status(void *ctx) {
+#ifdef SQLCIPHER_FIPS  
+  return FIPS_mode();
+#else
+  return 0;
+#endif
+}
+
+int sqlcipher_openssl_setup(sqlcipher_provider *p) {
+  p->activate = sqlcipher_openssl_activate;  
+  p->deactivate = sqlcipher_openssl_deactivate;
+  p->get_provider_name = sqlcipher_openssl_get_provider_name;
+  p->random = sqlcipher_openssl_random;
+  p->hmac = sqlcipher_openssl_hmac;
+  p->kdf = sqlcipher_openssl_kdf;
+  p->cipher = sqlcipher_openssl_cipher;
+  p->set_cipher = sqlcipher_openssl_set_cipher;
+  p->get_cipher = sqlcipher_openssl_get_cipher;
+  p->get_key_sz = sqlcipher_openssl_get_key_sz;
+  p->get_iv_sz = sqlcipher_openssl_get_iv_sz;
+  p->get_block_sz = sqlcipher_openssl_get_block_sz;
+  p->get_hmac_sz = sqlcipher_openssl_get_hmac_sz;
+  p->ctx_copy = sqlcipher_openssl_ctx_copy;
+  p->ctx_cmp = sqlcipher_openssl_ctx_cmp;
+  p->ctx_init = sqlcipher_openssl_ctx_init;
+  p->ctx_free = sqlcipher_openssl_ctx_free;
+  p->add_random = sqlcipher_openssl_add_random;
+  p->fips_status = sqlcipher_openssl_fips_status;
+  p->get_provider_version = sqlcipher_openssl_get_provider_version;
+  return SQLITE_OK;
+}
+
+#endif
+#endif
+/* END SQLCIPHER */
+
+/************** End of crypto_openssl.c **************************************/
+/************** Begin file crypto_cc.c ***************************************/
+/*
+** SQLCipher
+** http://sqlcipher.net
+**
+** Copyright (c) 2008 - 2013, ZETETIC LLC
+** All rights reserved.
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are met:
+**     * Redistributions of source code must retain the above copyright
+**       notice, this list of conditions and the following disclaimer.
+**     * Redistributions in binary form must reproduce the above copyright
+**       notice, this list of conditions and the following disclaimer in the
+**       documentation and/or other materials provided with the distribution.
+**     * Neither the name of the ZETETIC LLC nor the
+**       names of its contributors may be used to endorse or promote products
+**       derived from this software without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED BY ZETETIC LLC ''AS IS'' AND ANY
+** EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+** WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+** DISCLAIMED. IN NO EVENT SHALL ZETETIC LLC BE LIABLE FOR ANY
+** DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+** (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+** SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+**
+*/
+/* BEGIN SQLCIPHER */
+#ifdef SQLITE_HAS_CODEC
+#ifdef SQLCIPHER_CRYPTO_CC
+/* #include "crypto.h" */
+/* #include "sqlcipher.h" */
+#include <CommonCrypto/CommonCrypto.h>
+#include <Security/SecRandom.h>
+#include <CoreFoundation/CoreFoundation.h>
+
+static int sqlcipher_cc_add_random(void *ctx, void *buffer, int length) {
+  return SQLITE_OK;
+}
+
+/* generate a defined number of random bytes */
+static int sqlcipher_cc_random (void *ctx, void *buffer, int length) {
+  return (SecRandomCopyBytes(kSecRandomDefault, length, (uint8_t *)buffer) == 0) ? SQLITE_OK : SQLITE_ERROR;
+}
+
+static const char* sqlcipher_cc_get_provider_name(void *ctx) {
+  return "commoncrypto";
+}
+
+static const char* sqlcipher_cc_get_provider_version(void *ctx) {
+#if TARGET_OS_MAC
+  CFTypeRef version;
+  CFBundleRef bundle = CFBundleGetBundleWithIdentifier(CFSTR("com.apple.security"));
+  if(bundle == NULL) {
+    return "unknown";
+  }
+  version = CFBundleGetValueForInfoDictionaryKey(bundle, CFSTR("CFBundleShortVersionString"));
+  return CFStringGetCStringPtr(version, kCFStringEncodingUTF8);
+#else
+  return "unknown";
+#endif
+}
+
+static int sqlcipher_cc_hmac(void *ctx, unsigned char *hmac_key, int key_sz, unsigned char *in, int in_sz, unsigned char *in2, int in2_sz, unsigned char *out) {
+  CCHmacContext hmac_context;
+  CCHmacInit(&hmac_context, kCCHmacAlgSHA1, hmac_key, key_sz);
+  CCHmacUpdate(&hmac_context, in, in_sz);
+  CCHmacUpdate(&hmac_context, in2, in2_sz);
+  CCHmacFinal(&hmac_context, out);
+  return SQLITE_OK; 
+}
+
+static int sqlcipher_cc_kdf(void *ctx, const unsigned char *pass, int pass_sz, unsigned char* salt, int salt_sz, int workfactor, int key_sz, unsigned char *key) {
+  CCKeyDerivationPBKDF(kCCPBKDF2, (const char *)pass, pass_sz, salt, salt_sz, kCCPRFHmacAlgSHA1, workfactor, key, key_sz);
+  return SQLITE_OK; 
+}
+
+static int sqlcipher_cc_cipher(void *ctx, int mode, unsigned char *key, int key_sz, unsigned char *iv, unsigned char *in, int in_sz, unsigned char *out) {
+  CCCryptorRef cryptor;
+  size_t tmp_csz, csz;
+  CCOperation op = mode == CIPHER_ENCRYPT ? kCCEncrypt : kCCDecrypt;
+
+  CCCryptorCreate(op, kCCAlgorithmAES128, 0, key, kCCKeySizeAES256, iv, &cryptor);
+  CCCryptorUpdate(cryptor, in, in_sz, out, in_sz, &tmp_csz);
+  csz = tmp_csz;
+  out += tmp_csz;
+  CCCryptorFinal(cryptor, out, in_sz - csz, &tmp_csz);
+  csz += tmp_csz;
+  CCCryptorRelease(cryptor);
+  assert(in_sz == csz);
+
+  return SQLITE_OK; 
+}
+
+static int sqlcipher_cc_set_cipher(void *ctx, const char *cipher_name) {
+  return SQLITE_OK;
+}
+
+static const char* sqlcipher_cc_get_cipher(void *ctx) {
+  return "aes-256-cbc";
+}
+
+static int sqlcipher_cc_get_key_sz(void *ctx) {
+  return kCCKeySizeAES256;
+}
+
+static int sqlcipher_cc_get_iv_sz(void *ctx) {
+  return kCCBlockSizeAES128;
+}
+
+static int sqlcipher_cc_get_block_sz(void *ctx) {
+  return kCCBlockSizeAES128;
+}
+
+static int sqlcipher_cc_get_hmac_sz(void *ctx) {
+  return CC_SHA1_DIGEST_LENGTH;
+}
+
+static int sqlcipher_cc_ctx_copy(void *target_ctx, void *source_ctx) {
+  return SQLITE_OK;
+}
+
+static int sqlcipher_cc_ctx_cmp(void *c1, void *c2) {
+  return 1; /* always indicate contexts are the same */
+}
+
+static int sqlcipher_cc_ctx_init(void **ctx) {
+  return SQLITE_OK;
+}
+
+static int sqlcipher_cc_ctx_free(void **ctx) {
+  return SQLITE_OK;
+}
+
+static int sqlcipher_cc_fips_status(void *ctx) {
+  return 0;
+}
+
+int sqlcipher_cc_setup(sqlcipher_provider *p) {
+  p->random = sqlcipher_cc_random;
+  p->get_provider_name = sqlcipher_cc_get_provider_name;
+  p->hmac = sqlcipher_cc_hmac;
+  p->kdf = sqlcipher_cc_kdf;
+  p->cipher = sqlcipher_cc_cipher;
+  p->set_cipher = sqlcipher_cc_set_cipher;
+  p->get_cipher = sqlcipher_cc_get_cipher;
+  p->get_key_sz = sqlcipher_cc_get_key_sz;
+  p->get_iv_sz = sqlcipher_cc_get_iv_sz;
+  p->get_block_sz = sqlcipher_cc_get_block_sz;
+  p->get_hmac_sz = sqlcipher_cc_get_hmac_sz;
+  p->ctx_copy = sqlcipher_cc_ctx_copy;
+  p->ctx_cmp = sqlcipher_cc_ctx_cmp;
+  p->ctx_init = sqlcipher_cc_ctx_init;
+  p->ctx_free = sqlcipher_cc_ctx_free;
+  p->add_random = sqlcipher_cc_add_random;
+  p->fips_status = sqlcipher_cc_fips_status;
+  p->get_provider_version = sqlcipher_cc_get_provider_version;
+  return SQLITE_OK;
+}
+
+#endif
+#endif
+/* END SQLCIPHER */
+
+/************** End of crypto_cc.c *******************************************/
+/************** Begin file global.c ******************************************/
+/*
+** 2008 June 13
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains definitions of global variables and constants.
+*/
+/* #include "sqliteInt.h" */
+
+/* An array to map all upper-case characters into their corresponding
+** lower-case character. 
+**
+** SQLite only considers US-ASCII (or EBCDIC) characters.  We do not
+** handle case conversions for the UTF character set since the tables
+** involved are nearly as big or bigger than SQLite itself.
+*/
+SQLITE_PRIVATE const unsigned char sqlite3UpperToLower[] = {
+#ifdef SQLITE_ASCII
+      0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17,
+     18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
+     36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53,
+     54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 97, 98, 99,100,101,102,103,
+    104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,
+    122, 91, 92, 93, 94, 95, 96, 97, 98, 99,100,101,102,103,104,105,106,107,
+    108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,
+    126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,
+    144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,
+    162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,
+    180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,
+    198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,
+    216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,
+    234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,
+    252,253,254,255
+#endif
+#ifdef SQLITE_EBCDIC
+      0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, /* 0x */
+     16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, /* 1x */
+     32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, /* 2x */
+     48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, /* 3x */
+     64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, /* 4x */
+     80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, /* 5x */
+     96, 97, 98, 99,100,101,102,103,104,105,106,107,108,109,110,111, /* 6x */
+    112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127, /* 7x */
+    128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143, /* 8x */
+    144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159, /* 9x */
+    160,161,162,163,164,165,166,167,168,169,170,171,140,141,142,175, /* Ax */
+    176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191, /* Bx */
+    192,129,130,131,132,133,134,135,136,137,202,203,204,205,206,207, /* Cx */
+    208,145,146,147,148,149,150,151,152,153,218,219,220,221,222,223, /* Dx */
+    224,225,162,163,164,165,166,167,168,169,234,235,236,237,238,239, /* Ex */
+    240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255, /* Fx */
+#endif
+};
+
+/*
+** The following 256 byte lookup table is used to support SQLites built-in
+** equivalents to the following standard library functions:
+**
+**   isspace()                        0x01
+**   isalpha()                        0x02
+**   isdigit()                        0x04
+**   isalnum()                        0x06
+**   isxdigit()                       0x08
+**   toupper()                        0x20
+**   SQLite identifier character      0x40
+**   Quote character                  0x80
+**
+** Bit 0x20 is set if the mapped character requires translation to upper
+** case. i.e. if the character is a lower-case ASCII character.
+** If x is a lower-case ASCII character, then its upper-case equivalent
+** is (x - 0x20). Therefore toupper() can be implemented as:
+**
+**   (x & ~(map[x]&0x20))
+**
+** The equivalent of tolower() is implemented using the sqlite3UpperToLower[]
+** array. tolower() is used more often than toupper() by SQLite.
+**
+** Bit 0x40 is set if the character is non-alphanumeric and can be used in an 
+** SQLite identifier.  Identifiers are alphanumerics, "_", "$", and any
+** non-ASCII UTF character. Hence the test for whether or not a character is
+** part of an identifier is 0x46.
+*/
+#ifdef SQLITE_ASCII
+SQLITE_PRIVATE const unsigned char sqlite3CtypeMap[256] = {
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 00..07    ........ */
+  0x00, 0x01, 0x01, 0x01, 0x01, 0x01, 0x00, 0x00,  /* 08..0f    ........ */
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 10..17    ........ */
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 18..1f    ........ */
+  0x01, 0x00, 0x80, 0x00, 0x40, 0x00, 0x00, 0x80,  /* 20..27     !"#$%&' */
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 28..2f    ()*+,-./ */
+  0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c,  /* 30..37    01234567 */
+  0x0c, 0x0c, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 38..3f    89:;<=>? */
+
+  0x00, 0x0a, 0x0a, 0x0a, 0x0a, 0x0a, 0x0a, 0x02,  /* 40..47    @ABCDEFG */
+  0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,  /* 48..4f    HIJKLMNO */
+  0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,  /* 50..57    PQRSTUVW */
+  0x02, 0x02, 0x02, 0x80, 0x00, 0x00, 0x00, 0x40,  /* 58..5f    XYZ[\]^_ */
+  0x80, 0x2a, 0x2a, 0x2a, 0x2a, 0x2a, 0x2a, 0x22,  /* 60..67    `abcdefg */
+  0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22,  /* 68..6f    hijklmno */
+  0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22,  /* 70..77    pqrstuvw */
+  0x22, 0x22, 0x22, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 78..7f    xyz{|}~. */
+
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* 80..87    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* 88..8f    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* 90..97    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* 98..9f    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* a0..a7    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* a8..af    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* b0..b7    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* b8..bf    ........ */
+
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* c0..c7    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* c8..cf    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* d0..d7    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* d8..df    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* e0..e7    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* e8..ef    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* f0..f7    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40   /* f8..ff    ........ */
+};
+#endif
+
+/* EVIDENCE-OF: R-02982-34736 In order to maintain full backwards
+** compatibility for legacy applications, the URI filename capability is
+** disabled by default.
+**
+** EVIDENCE-OF: R-38799-08373 URI filenames can be enabled or disabled
+** using the SQLITE_USE_URI=1 or SQLITE_USE_URI=0 compile-time options.
+**
+** EVIDENCE-OF: R-43642-56306 By default, URI handling is globally
+** disabled. The default value may be changed by compiling with the
+** SQLITE_USE_URI symbol defined.
+*/
+#ifndef SQLITE_USE_URI
+# define  SQLITE_USE_URI 0
+#endif
+
+/* EVIDENCE-OF: R-38720-18127 The default setting is determined by the
+** SQLITE_ALLOW_COVERING_INDEX_SCAN compile-time option, or is "on" if
+** that compile-time option is omitted.
+*/
+#ifndef SQLITE_ALLOW_COVERING_INDEX_SCAN
+# define SQLITE_ALLOW_COVERING_INDEX_SCAN 1
+#endif
+
+/* The minimum PMA size is set to this value multiplied by the database
+** page size in bytes.
+*/
+#ifndef SQLITE_SORTER_PMASZ
+# define SQLITE_SORTER_PMASZ 250
+#endif
+
+/* Statement journals spill to disk when their size exceeds the following
+** threshold (in bytes). 0 means that statement journals are created and
+** written to disk immediately (the default behavior for SQLite versions
+** before 3.12.0).  -1 means always keep the entire statement journal in
+** memory.  (The statement journal is also always held entirely in memory
+** if journal_mode=MEMORY or if temp_store=MEMORY, regardless of this
+** setting.)
+*/
+#ifndef SQLITE_STMTJRNL_SPILL 
+# define SQLITE_STMTJRNL_SPILL (64*1024)
+#endif
+
+/*
+** The following singleton contains the global configuration for
+** the SQLite library.
+*/
+SQLITE_PRIVATE SQLITE_WSD struct Sqlite3Config sqlite3Config = {
+   SQLITE_DEFAULT_MEMSTATUS,  /* bMemstat */
+   1,                         /* bCoreMutex */
+   SQLITE_THREADSAFE==1,      /* bFullMutex */
+   SQLITE_USE_URI,            /* bOpenUri */
+   SQLITE_ALLOW_COVERING_INDEX_SCAN,   /* bUseCis */
+   0x7ffffffe,                /* mxStrlen */
+   0,                         /* neverCorrupt */
+   128,                       /* szLookaside */
+   500,                       /* nLookaside */
+   SQLITE_STMTJRNL_SPILL,     /* nStmtSpill */
+   {0,0,0,0,0,0,0,0},         /* m */
+   {0,0,0,0,0,0,0,0,0},       /* mutex */
+   {0,0,0,0,0,0,0,0,0,0,0,0,0},/* pcache2 */
+   (void*)0,                  /* pHeap */
+   0,                         /* nHeap */
+   0, 0,                      /* mnHeap, mxHeap */
+   SQLITE_DEFAULT_MMAP_SIZE,  /* szMmap */
+   SQLITE_MAX_MMAP_SIZE,      /* mxMmap */
+   (void*)0,                  /* pScratch */
+   0,                         /* szScratch */
+   0,                         /* nScratch */
+   (void*)0,                  /* pPage */
+   0,                         /* szPage */
+   SQLITE_DEFAULT_PCACHE_INITSZ, /* nPage */
+   0,                         /* mxParserStack */
+   0,                         /* sharedCacheEnabled */
+   SQLITE_SORTER_PMASZ,       /* szPma */
+   /* All the rest should always be initialized to zero */
+   0,                         /* isInit */
+   0,                         /* inProgress */
+   0,                         /* isMutexInit */
+   0,                         /* isMallocInit */
+   0,                         /* isPCacheInit */
+   0,                         /* nRefInitMutex */
+   0,                         /* pInitMutex */
+   0,                         /* xLog */
+   0,                         /* pLogArg */
+#ifdef SQLITE_ENABLE_SQLLOG
+   0,                         /* xSqllog */
+   0,                         /* pSqllogArg */
+#endif
+#ifdef SQLITE_VDBE_COVERAGE
+   0,                         /* xVdbeBranch */
+   0,                         /* pVbeBranchArg */
+#endif
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+   0,                         /* xTestCallback */
+#endif
+   0,                         /* bLocaltimeFault */
+   0x7ffffffe                 /* iOnceResetThreshold */
+};
+
+/*
+** Hash table for global functions - functions common to all
+** database connections.  After initialization, this table is
+** read-only.
+*/
+SQLITE_PRIVATE FuncDefHash sqlite3BuiltinFunctions;
+
+/*
+** Constant tokens for values 0 and 1.
+*/
+SQLITE_PRIVATE const Token sqlite3IntTokens[] = {
+   { "0", 1 },
+   { "1", 1 }
+};
+
+
+/*
+** The value of the "pending" byte must be 0x40000000 (1 byte past the
+** 1-gibabyte boundary) in a compatible database.  SQLite never uses
+** the database page that contains the pending byte.  It never attempts
+** to read or write that page.  The pending byte page is set aside
+** for use by the VFS layers as space for managing file locks.
+**
+** During testing, it is often desirable to move the pending byte to
+** a different position in the file.  This allows code that has to
+** deal with the pending byte to run on files that are much smaller
+** than 1 GiB.  The sqlite3_test_control() interface can be used to
+** move the pending byte.
+**
+** IMPORTANT:  Changing the pending byte to any value other than
+** 0x40000000 results in an incompatible database file format!
+** Changing the pending byte during operation will result in undefined
+** and incorrect behavior.
+*/
+#ifndef SQLITE_OMIT_WSD
+SQLITE_PRIVATE int sqlite3PendingByte = 0x40000000;
+#endif
+
+/* #include "opcodes.h" */
+/*
+** Properties of opcodes.  The OPFLG_INITIALIZER macro is
+** created by mkopcodeh.awk during compilation.  Data is obtained
+** from the comments following the "case OP_xxxx:" statements in
+** the vdbe.c file.  
+*/
+SQLITE_PRIVATE const unsigned char sqlite3OpcodeProperty[] = OPFLG_INITIALIZER;
+
+/*
+** Name of the default collating sequence
+*/
+SQLITE_PRIVATE const char sqlite3StrBINARY[] = "BINARY";
+
+/************** End of global.c **********************************************/
+/************** Begin file ctime.c *******************************************/
+/*
+** 2010 February 23
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file implements routines used to report what compile-time options
+** SQLite was built with.
+*/
+
+#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
+
+/* #include "sqliteInt.h" */
+
+/*
+** An array of names of all compile-time options.  This array should 
+** be sorted A-Z.
+**
+** This array looks large, but in a typical installation actually uses
+** only a handful of compile-time options, so most times this array is usually
+** rather short and uses little memory space.
+*/
+static const char * const azCompileOpt[] = {
+
+/* These macros are provided to "stringify" the value of the define
+** for those options in which the value is meaningful. */
+#define CTIMEOPT_VAL_(opt) #opt
+#define CTIMEOPT_VAL(opt) CTIMEOPT_VAL_(opt)
+
+#if SQLITE_32BIT_ROWID
+  "32BIT_ROWID",
+#endif
+#if SQLITE_4_BYTE_ALIGNED_MALLOC
+  "4_BYTE_ALIGNED_MALLOC",
+#endif
+#if SQLITE_CASE_SENSITIVE_LIKE
+  "CASE_SENSITIVE_LIKE",
+#endif
+#if SQLITE_CHECK_PAGES
+  "CHECK_PAGES",
+#endif
+#if defined(__clang__) && defined(__clang_major__)
+  "COMPILER=clang-" CTIMEOPT_VAL(__clang_major__) "."
+                    CTIMEOPT_VAL(__clang_minor__) "."
+                    CTIMEOPT_VAL(__clang_patchlevel__),
+#elif defined(_MSC_VER)
+  "COMPILER=msvc-" CTIMEOPT_VAL(_MSC_VER),
+#elif defined(__GNUC__) && defined(__VERSION__)
+  "COMPILER=gcc-" __VERSION__,
+#endif
+#if SQLITE_COVERAGE_TEST
+  "COVERAGE_TEST",
+#endif
+#if SQLITE_DEBUG
+  "DEBUG",
+#endif
+#if SQLITE_DEFAULT_LOCKING_MODE
+  "DEFAULT_LOCKING_MODE=" CTIMEOPT_VAL(SQLITE_DEFAULT_LOCKING_MODE),
+#endif
+#if defined(SQLITE_DEFAULT_MMAP_SIZE) && !defined(SQLITE_DEFAULT_MMAP_SIZE_xc)
+  "DEFAULT_MMAP_SIZE=" CTIMEOPT_VAL(SQLITE_DEFAULT_MMAP_SIZE),
+#endif
+#if SQLITE_DISABLE_DIRSYNC
+  "DISABLE_DIRSYNC",
+#endif
+#if SQLITE_DISABLE_LFS
+  "DISABLE_LFS",
+#endif
+#if SQLITE_ENABLE_8_3_NAMES
+  "ENABLE_8_3_NAMES=" CTIMEOPT_VAL(SQLITE_ENABLE_8_3_NAMES),
+#endif
+#if SQLITE_ENABLE_API_ARMOR
+  "ENABLE_API_ARMOR",
+#endif
+#if SQLITE_ENABLE_ATOMIC_WRITE
+  "ENABLE_ATOMIC_WRITE",
+#endif
+#if SQLITE_ENABLE_CEROD
+  "ENABLE_CEROD",
+#endif
+#if SQLITE_ENABLE_COLUMN_METADATA
+  "ENABLE_COLUMN_METADATA",
+#endif
+#if SQLITE_ENABLE_DBSTAT_VTAB
+  "ENABLE_DBSTAT_VTAB",
+#endif
+#if SQLITE_ENABLE_EXPENSIVE_ASSERT
+  "ENABLE_EXPENSIVE_ASSERT",
+#endif
+#if SQLITE_ENABLE_FTS1
+  "ENABLE_FTS1",
+#endif
+#if SQLITE_ENABLE_FTS2
+  "ENABLE_FTS2",
+#endif
+#if SQLITE_ENABLE_FTS3
+  "ENABLE_FTS3",
+#endif
+#if SQLITE_ENABLE_FTS3_PARENTHESIS
+  "ENABLE_FTS3_PARENTHESIS",
+#endif
+#if SQLITE_ENABLE_FTS4
+  "ENABLE_FTS4",
+#endif
+#if SQLITE_ENABLE_FTS5
+  "ENABLE_FTS5",
+#endif
+#if SQLITE_ENABLE_ICU
+  "ENABLE_ICU",
+#endif
+#if SQLITE_ENABLE_IOTRACE
+  "ENABLE_IOTRACE",
+#endif
+#if SQLITE_ENABLE_JSON1
+  "ENABLE_JSON1",
+#endif
+#if SQLITE_ENABLE_LOAD_EXTENSION
+  "ENABLE_LOAD_EXTENSION",
+#endif
+#if SQLITE_ENABLE_LOCKING_STYLE
+  "ENABLE_LOCKING_STYLE=" CTIMEOPT_VAL(SQLITE_ENABLE_LOCKING_STYLE),
+#endif
+#if SQLITE_ENABLE_MEMORY_MANAGEMENT
+  "ENABLE_MEMORY_MANAGEMENT",
+#endif
+#if SQLITE_ENABLE_MEMSYS3
+  "ENABLE_MEMSYS3",
+#endif
+#if SQLITE_ENABLE_MEMSYS5
+  "ENABLE_MEMSYS5",
+#endif
+#if SQLITE_ENABLE_OVERSIZE_CELL_CHECK
+  "ENABLE_OVERSIZE_CELL_CHECK",
+#endif
+#if SQLITE_ENABLE_RTREE
+  "ENABLE_RTREE",
+#endif
+#if defined(SQLITE_ENABLE_STAT4)
+  "ENABLE_STAT4",
+#elif defined(SQLITE_ENABLE_STAT3)
+  "ENABLE_STAT3",
+#endif
+#if SQLITE_ENABLE_UNLOCK_NOTIFY
+  "ENABLE_UNLOCK_NOTIFY",
+#endif
+#if SQLITE_ENABLE_UPDATE_DELETE_LIMIT
+  "ENABLE_UPDATE_DELETE_LIMIT",
+#endif
+#if SQLITE_HAS_CODEC
+  "HAS_CODEC",
+#endif
+#if HAVE_ISNAN || SQLITE_HAVE_ISNAN
+  "HAVE_ISNAN",
+#endif
+#if SQLITE_HOMEGROWN_RECURSIVE_MUTEX
+  "HOMEGROWN_RECURSIVE_MUTEX",
+#endif
+#if SQLITE_IGNORE_AFP_LOCK_ERRORS
+  "IGNORE_AFP_LOCK_ERRORS",
+#endif
+#if SQLITE_IGNORE_FLOCK_LOCK_ERRORS
+  "IGNORE_FLOCK_LOCK_ERRORS",
+#endif
+#ifdef SQLITE_INT64_TYPE
+  "INT64_TYPE",
+#endif
+#ifdef SQLITE_LIKE_DOESNT_MATCH_BLOBS
+  "LIKE_DOESNT_MATCH_BLOBS",
+#endif
+#if SQLITE_LOCK_TRACE
+  "LOCK_TRACE",
+#endif
+#if defined(SQLITE_MAX_MMAP_SIZE) && !defined(SQLITE_MAX_MMAP_SIZE_xc)
+  "MAX_MMAP_SIZE=" CTIMEOPT_VAL(SQLITE_MAX_MMAP_SIZE),
+#endif
+#ifdef SQLITE_MAX_SCHEMA_RETRY
+  "MAX_SCHEMA_RETRY=" CTIMEOPT_VAL(SQLITE_MAX_SCHEMA_RETRY),
+#endif
+#if SQLITE_MEMDEBUG
+  "MEMDEBUG",
+#endif
+#if SQLITE_MIXED_ENDIAN_64BIT_FLOAT
+  "MIXED_ENDIAN_64BIT_FLOAT",
+#endif
+#if SQLITE_NO_SYNC
+  "NO_SYNC",
+#endif
+#if SQLITE_OMIT_ALTERTABLE
+  "OMIT_ALTERTABLE",
+#endif
+#if SQLITE_OMIT_ANALYZE
+  "OMIT_ANALYZE",
+#endif
+#if SQLITE_OMIT_ATTACH
+  "OMIT_ATTACH",
+#endif
+#if SQLITE_OMIT_AUTHORIZATION
+  "OMIT_AUTHORIZATION",
+#endif
+#if SQLITE_OMIT_AUTOINCREMENT
+  "OMIT_AUTOINCREMENT",
+#endif
+#if SQLITE_OMIT_AUTOINIT
+  "OMIT_AUTOINIT",
+#endif
+#if SQLITE_OMIT_AUTOMATIC_INDEX
+  "OMIT_AUTOMATIC_INDEX",
+#endif
+#if SQLITE_OMIT_AUTORESET
+  "OMIT_AUTORESET",
+#endif
+#if SQLITE_OMIT_AUTOVACUUM
+  "OMIT_AUTOVACUUM",
+#endif
+#if SQLITE_OMIT_BETWEEN_OPTIMIZATION
+  "OMIT_BETWEEN_OPTIMIZATION",
+#endif
+#if SQLITE_OMIT_BLOB_LITERAL
+  "OMIT_BLOB_LITERAL",
+#endif
+#if SQLITE_OMIT_BTREECOUNT
+  "OMIT_BTREECOUNT",
+#endif
+#if SQLITE_OMIT_BUILTIN_TEST
+  "OMIT_BUILTIN_TEST",
+#endif
+#if SQLITE_OMIT_CAST
+  "OMIT_CAST",
+#endif
+#if SQLITE_OMIT_CHECK
+  "OMIT_CHECK",
+#endif
+#if SQLITE_OMIT_COMPLETE
+  "OMIT_COMPLETE",
+#endif
+#if SQLITE_OMIT_COMPOUND_SELECT
+  "OMIT_COMPOUND_SELECT",
+#endif
+#if SQLITE_OMIT_CTE
+  "OMIT_CTE",
+#endif
+#if SQLITE_OMIT_DATETIME_FUNCS
+  "OMIT_DATETIME_FUNCS",
+#endif
+#if SQLITE_OMIT_DECLTYPE
+  "OMIT_DECLTYPE",
+#endif
+#if SQLITE_OMIT_DEPRECATED
+  "OMIT_DEPRECATED",
+#endif
+#if SQLITE_OMIT_DISKIO
+  "OMIT_DISKIO",
+#endif
+#if SQLITE_OMIT_EXPLAIN
+  "OMIT_EXPLAIN",
+#endif
+#if SQLITE_OMIT_FLAG_PRAGMAS
+  "OMIT_FLAG_PRAGMAS",
+#endif
+#if SQLITE_OMIT_FLOATING_POINT
+  "OMIT_FLOATING_POINT",
+#endif
+#if SQLITE_OMIT_FOREIGN_KEY
+  "OMIT_FOREIGN_KEY",
+#endif
+#if SQLITE_OMIT_GET_TABLE
+  "OMIT_GET_TABLE",
+#endif
+#if SQLITE_OMIT_INCRBLOB
+  "OMIT_INCRBLOB",
+#endif
+#if SQLITE_OMIT_INTEGRITY_CHECK
+  "OMIT_INTEGRITY_CHECK",
+#endif
+#if SQLITE_OMIT_LIKE_OPTIMIZATION
+  "OMIT_LIKE_OPTIMIZATION",
+#endif
+#if SQLITE_OMIT_LOAD_EXTENSION
+  "OMIT_LOAD_EXTENSION",
+#endif
+#if SQLITE_OMIT_LOCALTIME
+  "OMIT_LOCALTIME",
+#endif
+#if SQLITE_OMIT_LOOKASIDE
+  "OMIT_LOOKASIDE",
+#endif
+#if SQLITE_OMIT_MEMORYDB
+  "OMIT_MEMORYDB",
+#endif
+#if SQLITE_OMIT_OR_OPTIMIZATION
+  "OMIT_OR_OPTIMIZATION",
+#endif
+#if SQLITE_OMIT_PAGER_PRAGMAS
+  "OMIT_PAGER_PRAGMAS",
+#endif
+#if SQLITE_OMIT_PRAGMA
+  "OMIT_PRAGMA",
+#endif
+#if SQLITE_OMIT_PROGRESS_CALLBACK
+  "OMIT_PROGRESS_CALLBACK",
+#endif
+#if SQLITE_OMIT_QUICKBALANCE
+  "OMIT_QUICKBALANCE",
+#endif
+#if SQLITE_OMIT_REINDEX
+  "OMIT_REINDEX",
+#endif
+#if SQLITE_OMIT_SCHEMA_PRAGMAS
+  "OMIT_SCHEMA_PRAGMAS",
+#endif
+#if SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS
+  "OMIT_SCHEMA_VERSION_PRAGMAS",
+#endif
+#if SQLITE_OMIT_SHARED_CACHE
+  "OMIT_SHARED_CACHE",
+#endif
+#if SQLITE_OMIT_SUBQUERY
+  "OMIT_SUBQUERY",
+#endif
+#if SQLITE_OMIT_TCL_VARIABLE
+  "OMIT_TCL_VARIABLE",
+#endif
+#if SQLITE_OMIT_TEMPDB
+  "OMIT_TEMPDB",
+#endif
+#if SQLITE_OMIT_TRACE
+  "OMIT_TRACE",
+#endif
+#if SQLITE_OMIT_TRIGGER
+  "OMIT_TRIGGER",
+#endif
+#if SQLITE_OMIT_TRUNCATE_OPTIMIZATION
+  "OMIT_TRUNCATE_OPTIMIZATION",
+#endif
+#if SQLITE_OMIT_UTF16
+  "OMIT_UTF16",
+#endif
+#if SQLITE_OMIT_VACUUM
+  "OMIT_VACUUM",
+#endif
+#if SQLITE_OMIT_VIEW
+  "OMIT_VIEW",
+#endif
+#if SQLITE_OMIT_VIRTUALTABLE
+  "OMIT_VIRTUALTABLE",
+#endif
+#if SQLITE_OMIT_WAL
+  "OMIT_WAL",
+#endif
+#if SQLITE_OMIT_WSD
+  "OMIT_WSD",
+#endif
+#if SQLITE_OMIT_XFER_OPT
+  "OMIT_XFER_OPT",
+#endif
+#if SQLITE_PERFORMANCE_TRACE
+  "PERFORMANCE_TRACE",
+#endif
+#if SQLITE_PROXY_DEBUG
+  "PROXY_DEBUG",
+#endif
+#if SQLITE_RTREE_INT_ONLY
+  "RTREE_INT_ONLY",
+#endif
+#if SQLITE_SECURE_DELETE
+  "SECURE_DELETE",
+#endif
+#if SQLITE_SMALL_STACK
+  "SMALL_STACK",
+#endif
+#if SQLITE_SOUNDEX
+  "SOUNDEX",
+#endif
+#if SQLITE_SYSTEM_MALLOC
+  "SYSTEM_MALLOC",
+#endif
+#if SQLITE_TCL
+  "TCL",
+#endif
+#if defined(SQLITE_TEMP_STORE) && !defined(SQLITE_TEMP_STORE_xc)
+  "TEMP_STORE=" CTIMEOPT_VAL(SQLITE_TEMP_STORE),
+#endif
+#if SQLITE_TEST
+  "TEST",
+#endif
+#if defined(SQLITE_THREADSAFE)
+  "THREADSAFE=" CTIMEOPT_VAL(SQLITE_THREADSAFE),
+#endif
+#if SQLITE_USE_ALLOCA
+  "USE_ALLOCA",
+#endif
+#if SQLITE_USER_AUTHENTICATION
+  "USER_AUTHENTICATION",
+#endif
+#if SQLITE_WIN32_MALLOC
+  "WIN32_MALLOC",
+#endif
+#if SQLITE_ZERO_MALLOC
+  "ZERO_MALLOC"
+#endif
+};
+
+/*
+** Given the name of a compile-time option, return true if that option
+** was used and false if not.
+**
+** The name can optionally begin with "SQLITE_" but the "SQLITE_" prefix
+** is not required for a match.
+*/
+SQLITE_API int sqlite3_compileoption_used(const char *zOptName){
+  int i, n;
+
+#if SQLITE_ENABLE_API_ARMOR
+  if( zOptName==0 ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  if( sqlite3StrNICmp(zOptName, "SQLITE_", 7)==0 ) zOptName += 7;
+  n = sqlite3Strlen30(zOptName);
+
+  /* Since ArraySize(azCompileOpt) is normally in single digits, a
+  ** linear search is adequate.  No need for a binary search. */
+  for(i=0; i<ArraySize(azCompileOpt); i++){
+    if( sqlite3StrNICmp(zOptName, azCompileOpt[i], n)==0
+     && sqlite3IsIdChar((unsigned char)azCompileOpt[i][n])==0
+    ){
+      return 1;
+    }
+  }
+  return 0;
+}
+
+/*
+** Return the N-th compile-time option string.  If N is out of range,
+** return a NULL pointer.
+*/
+SQLITE_API const char *sqlite3_compileoption_get(int N){
+  if( N>=0 && N<ArraySize(azCompileOpt) ){
+    return azCompileOpt[N];
+  }
+  return 0;
+}
+
+#endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */
+
+/************** End of ctime.c ***********************************************/
+/************** Begin file status.c ******************************************/
+/*
+** 2008 June 18
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This module implements the sqlite3_status() interface and related
+** functionality.
+*/
+/* #include "sqliteInt.h" */
+/************** Include vdbeInt.h in the middle of status.c ******************/
+/************** Begin file vdbeInt.h *****************************************/
+/*
+** 2003 September 6
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This is the header file for information that is private to the
+** VDBE.  This information used to all be at the top of the single
+** source code file "vdbe.c".  When that file became too big (over
+** 6000 lines long) it was split up into several smaller files and
+** this header information was factored out.
+*/
+#ifndef SQLITE_VDBEINT_H
+#define SQLITE_VDBEINT_H
+
+/*
+** The maximum number of times that a statement will try to reparse
+** itself before giving up and returning SQLITE_SCHEMA.
+*/
+#ifndef SQLITE_MAX_SCHEMA_RETRY
+# define SQLITE_MAX_SCHEMA_RETRY 50
+#endif
+
+/*
+** VDBE_DISPLAY_P4 is true or false depending on whether or not the
+** "explain" P4 display logic is enabled.
+*/
+#if !defined(SQLITE_OMIT_EXPLAIN) || !defined(NDEBUG) \
+     || defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
+# define VDBE_DISPLAY_P4 1
+#else
+# define VDBE_DISPLAY_P4 0
+#endif
+
+/*
+** SQL is translated into a sequence of instructions to be
+** executed by a virtual machine.  Each instruction is an instance
+** of the following structure.
+*/
+typedef struct VdbeOp Op;
+
+/*
+** Boolean values
+*/
+typedef unsigned Bool;
+
+/* Opaque type used by code in vdbesort.c */
+typedef struct VdbeSorter VdbeSorter;
+
+/* Elements of the linked list at Vdbe.pAuxData */
+typedef struct AuxData AuxData;
+
+/* Types of VDBE cursors */
+#define CURTYPE_BTREE       0
+#define CURTYPE_SORTER      1
+#define CURTYPE_VTAB        2
+#define CURTYPE_PSEUDO      3
+
+/*
+** A VdbeCursor is an superclass (a wrapper) for various cursor objects:
+**
+**      * A b-tree cursor
+**          -  In the main database or in an ephemeral database
+**          -  On either an index or a table
+**      * A sorter
+**      * A virtual table
+**      * A one-row "pseudotable" stored in a single register
+*/
+typedef struct VdbeCursor VdbeCursor;
+struct VdbeCursor {
+  u8 eCurType;          /* One of the CURTYPE_* values above */
+  i8 iDb;               /* Index of cursor database in db->aDb[] (or -1) */
+  u8 nullRow;           /* True if pointing to a row with no data */
+  u8 deferredMoveto;    /* A call to sqlite3BtreeMoveto() is needed */
+  u8 isTable;           /* True for rowid tables.  False for indexes */
+#ifdef SQLITE_DEBUG
+  u8 seekOp;            /* Most recent seek operation on this cursor */
+  u8 wrFlag;            /* The wrFlag argument to sqlite3BtreeCursor() */
+#endif
+  Bool isEphemeral:1;   /* True for an ephemeral table */
+  Bool useRandomRowid:1;/* Generate new record numbers semi-randomly */
+  Bool isOrdered:1;     /* True if the table is not BTREE_UNORDERED */
+  Pgno pgnoRoot;        /* Root page of the open btree cursor */
+  i16 nField;           /* Number of fields in the header */
+  u16 nHdrParsed;       /* Number of header fields parsed so far */
+  union {
+    BtCursor *pCursor;          /* CURTYPE_BTREE.  Btree cursor */
+    sqlite3_vtab_cursor *pVCur; /* CURTYPE_VTAB.   Vtab cursor */
+    int pseudoTableReg;         /* CURTYPE_PSEUDO. Reg holding content. */
+    VdbeSorter *pSorter;        /* CURTYPE_SORTER. Sorter object */
+  } uc;
+  Btree *pBt;           /* Separate file holding temporary table */
+  KeyInfo *pKeyInfo;    /* Info about index keys needed by index cursors */
+  int seekResult;       /* Result of previous sqlite3BtreeMoveto() */
+  i64 seqCount;         /* Sequence counter */
+  i64 movetoTarget;     /* Argument to the deferred sqlite3BtreeMoveto() */
+  VdbeCursor *pAltCursor; /* Associated index cursor from which to read */
+  int *aAltMap;           /* Mapping from table to index column numbers */
+#ifdef SQLITE_ENABLE_COLUMN_USED_MASK
+  u64 maskUsed;         /* Mask of columns used by this cursor */
+#endif
+
+  /* Cached information about the header for the data record that the
+  ** cursor is currently pointing to.  Only valid if cacheStatus matches
+  ** Vdbe.cacheCtr.  Vdbe.cacheCtr will never take on the value of
+  ** CACHE_STALE and so setting cacheStatus=CACHE_STALE guarantees that
+  ** the cache is out of date.
+  **
+  ** aRow might point to (ephemeral) data for the current row, or it might
+  ** be NULL.
+  */
+  u32 cacheStatus;      /* Cache is valid if this matches Vdbe.cacheCtr */
+  u32 payloadSize;      /* Total number of bytes in the record */
+  u32 szRow;            /* Byte available in aRow */
+  u32 iHdrOffset;       /* Offset to next unparsed byte of the header */
+  const u8 *aRow;       /* Data for the current row, if all on one page */
+  u32 *aOffset;         /* Pointer to aType[nField] */
+  u32 aType[1];         /* Type values for all entries in the record */
+  /* 2*nField extra array elements allocated for aType[], beyond the one
+  ** static element declared in the structure.  nField total array slots for
+  ** aType[] and nField+1 array slots for aOffset[] */
+};
+
+
+/*
+** A value for VdbeCursor.cacheStatus that means the cache is always invalid.
+*/
+#define CACHE_STALE 0
+
+/*
+** When a sub-program is executed (OP_Program), a structure of this type
+** is allocated to store the current value of the program counter, as
+** well as the current memory cell array and various other frame specific
+** values stored in the Vdbe struct. When the sub-program is finished, 
+** these values are copied back to the Vdbe from the VdbeFrame structure,
+** restoring the state of the VM to as it was before the sub-program
+** began executing.
+**
+** The memory for a VdbeFrame object is allocated and managed by a memory
+** cell in the parent (calling) frame. When the memory cell is deleted or
+** overwritten, the VdbeFrame object is not freed immediately. Instead, it
+** is linked into the Vdbe.pDelFrame list. The contents of the Vdbe.pDelFrame
+** list is deleted when the VM is reset in VdbeHalt(). The reason for doing
+** this instead of deleting the VdbeFrame immediately is to avoid recursive
+** calls to sqlite3VdbeMemRelease() when the memory cells belonging to the
+** child frame are released.
+**
+** The currently executing frame is stored in Vdbe.pFrame. Vdbe.pFrame is
+** set to NULL if the currently executing frame is the main program.
+*/
+typedef struct VdbeFrame VdbeFrame;
+struct VdbeFrame {
+  Vdbe *v;                /* VM this frame belongs to */
+  VdbeFrame *pParent;     /* Parent of this frame, or NULL if parent is main */
+  Op *aOp;                /* Program instructions for parent frame */
+  i64 *anExec;            /* Event counters from parent frame */
+  Mem *aMem;              /* Array of memory cells for parent frame */
+  VdbeCursor **apCsr;     /* Array of Vdbe cursors for parent frame */
+  void *token;            /* Copy of SubProgram.token */
+  i64 lastRowid;          /* Last insert rowid (sqlite3.lastRowid) */
+  AuxData *pAuxData;      /* Linked list of auxdata allocations */
+  int nCursor;            /* Number of entries in apCsr */
+  int pc;                 /* Program Counter in parent (calling) frame */
+  int nOp;                /* Size of aOp array */
+  int nMem;               /* Number of entries in aMem */
+  int nChildMem;          /* Number of memory cells for child frame */
+  int nChildCsr;          /* Number of cursors for child frame */
+  int nChange;            /* Statement changes (Vdbe.nChange)     */
+  int nDbChange;          /* Value of db->nChange */
+};
+
+#define VdbeFrameMem(p) ((Mem *)&((u8 *)p)[ROUND8(sizeof(VdbeFrame))])
+
+/*
+** Internally, the vdbe manipulates nearly all SQL values as Mem
+** structures. Each Mem struct may cache multiple representations (string,
+** integer etc.) of the same value.
+*/
+struct Mem {
+  union MemValue {
+    double r;           /* Real value used when MEM_Real is set in flags */
+    i64 i;              /* Integer value used when MEM_Int is set in flags */
+    int nZero;          /* Used when bit MEM_Zero is set in flags */
+    FuncDef *pDef;      /* Used only when flags==MEM_Agg */
+    RowSet *pRowSet;    /* Used only when flags==MEM_RowSet */
+    VdbeFrame *pFrame;  /* Used when flags==MEM_Frame */
+  } u;
+  u16 flags;          /* Some combination of MEM_Null, MEM_Str, MEM_Dyn, etc. */
+  u8  enc;            /* SQLITE_UTF8, SQLITE_UTF16BE, SQLITE_UTF16LE */
+  u8  eSubtype;       /* Subtype for this value */
+  int n;              /* Number of characters in string value, excluding '\0' */
+  char *z;            /* String or BLOB value */
+  /* ShallowCopy only needs to copy the information above */
+  char *zMalloc;      /* Space to hold MEM_Str or MEM_Blob if szMalloc>0 */
+  int szMalloc;       /* Size of the zMalloc allocation */
+  u32 uTemp;          /* Transient storage for serial_type in OP_MakeRecord */
+  sqlite3 *db;        /* The associated database connection */
+  void (*xDel)(void*);/* Destructor for Mem.z - only valid if MEM_Dyn */
+#ifdef SQLITE_DEBUG
+  Mem *pScopyFrom;    /* This Mem is a shallow copy of pScopyFrom */
+  void *pFiller;      /* So that sizeof(Mem) is a multiple of 8 */
+#endif
+};
+
+/*
+** Size of struct Mem not including the Mem.zMalloc member or anything that
+** follows.
+*/
+#define MEMCELLSIZE offsetof(Mem,zMalloc)
+
+/* One or more of the following flags are set to indicate the validOK
+** representations of the value stored in the Mem struct.
+**
+** If the MEM_Null flag is set, then the value is an SQL NULL value.
+** No other flags may be set in this case.
+**
+** If the MEM_Str flag is set then Mem.z points at a string representation.
+** Usually this is encoded in the same unicode encoding as the main
+** database (see below for exceptions). If the MEM_Term flag is also
+** set, then the string is nul terminated. The MEM_Int and MEM_Real 
+** flags may coexist with the MEM_Str flag.
+*/
+#define MEM_Null      0x0001   /* Value is NULL */
+#define MEM_Str       0x0002   /* Value is a string */
+#define MEM_Int       0x0004   /* Value is an integer */
+#define MEM_Real      0x0008   /* Value is a real number */
+#define MEM_Blob      0x0010   /* Value is a BLOB */
+#define MEM_AffMask   0x001f   /* Mask of affinity bits */
+#define MEM_RowSet    0x0020   /* Value is a RowSet object */
+#define MEM_Frame     0x0040   /* Value is a VdbeFrame object */
+#define MEM_Undefined 0x0080   /* Value is undefined */
+#define MEM_Cleared   0x0100   /* NULL set by OP_Null, not from data */
+#define MEM_TypeMask  0x81ff   /* Mask of type bits */
+
+
+/* Whenever Mem contains a valid string or blob representation, one of
+** the following flags must be set to determine the memory management
+** policy for Mem.z.  The MEM_Term flag tells us whether or not the
+** string is \000 or \u0000 terminated
+*/
+#define MEM_Term      0x0200   /* String rep is nul terminated */
+#define MEM_Dyn       0x0400   /* Need to call Mem.xDel() on Mem.z */
+#define MEM_Static    0x0800   /* Mem.z points to a static string */
+#define MEM_Ephem     0x1000   /* Mem.z points to an ephemeral string */
+#define MEM_Agg       0x2000   /* Mem.z points to an agg function context */
+#define MEM_Zero      0x4000   /* Mem.i contains count of 0s appended to blob */
+#define MEM_Subtype   0x8000   /* Mem.eSubtype is valid */
+#ifdef SQLITE_OMIT_INCRBLOB
+  #undef MEM_Zero
+  #define MEM_Zero 0x0000
+#endif
+
+/* Return TRUE if Mem X contains dynamically allocated content - anything
+** that needs to be deallocated to avoid a leak.
+*/
+#define VdbeMemDynamic(X)  \
+  (((X)->flags&(MEM_Agg|MEM_Dyn|MEM_RowSet|MEM_Frame))!=0)
+
+/*
+** Clear any existing type flags from a Mem and replace them with f
+*/
+#define MemSetTypeFlag(p, f) \
+   ((p)->flags = ((p)->flags&~(MEM_TypeMask|MEM_Zero))|f)
+
+/*
+** Return true if a memory cell is not marked as invalid.  This macro
+** is for use inside assert() statements only.
+*/
+#ifdef SQLITE_DEBUG
+#define memIsValid(M)  ((M)->flags & MEM_Undefined)==0
+#endif
+
+/*
+** Each auxiliary data pointer stored by a user defined function 
+** implementation calling sqlite3_set_auxdata() is stored in an instance
+** of this structure. All such structures associated with a single VM
+** are stored in a linked list headed at Vdbe.pAuxData. All are destroyed
+** when the VM is halted (if not before).
+*/
+struct AuxData {
+  int iOp;                        /* Instruction number of OP_Function opcode */
+  int iArg;                       /* Index of function argument. */
+  void *pAux;                     /* Aux data pointer */
+  void (*xDelete)(void *);        /* Destructor for the aux data */
+  AuxData *pNext;                 /* Next element in list */
+};
+
+/*
+** The "context" argument for an installable function.  A pointer to an
+** instance of this structure is the first argument to the routines used
+** implement the SQL functions.
+**
+** There is a typedef for this structure in sqlite.h.  So all routines,
+** even the public interface to SQLite, can use a pointer to this structure.
+** But this file is the only place where the internal details of this
+** structure are known.
+**
+** This structure is defined inside of vdbeInt.h because it uses substructures
+** (Mem) which are only defined there.
+*/
+struct sqlite3_context {
+  Mem *pOut;              /* The return value is stored here */
+  FuncDef *pFunc;         /* Pointer to function information */
+  Mem *pMem;              /* Memory cell used to store aggregate context */
+  Vdbe *pVdbe;            /* The VM that owns this context */
+  int iOp;                /* Instruction number of OP_Function */
+  int isError;            /* Error code returned by the function. */
+  u8 skipFlag;            /* Skip accumulator loading if true */
+  u8 fErrorOrAux;         /* isError!=0 or pVdbe->pAuxData modified */
+  u8 argc;                /* Number of arguments */
+  sqlite3_value *argv[1]; /* Argument set */
+};
+
+/* A bitfield type for use inside of structures.  Always follow with :N where
+** N is the number of bits.
+*/
+typedef unsigned bft;  /* Bit Field Type */
+
+typedef struct ScanStatus ScanStatus;
+struct ScanStatus {
+  int addrExplain;                /* OP_Explain for loop */
+  int addrLoop;                   /* Address of "loops" counter */
+  int addrVisit;                  /* Address of "rows visited" counter */
+  int iSelectID;                  /* The "Select-ID" for this loop */
+  LogEst nEst;                    /* Estimated output rows per loop */
+  char *zName;                    /* Name of table or index */
+};
+
+/*
+** An instance of the virtual machine.  This structure contains the complete
+** state of the virtual machine.
+**
+** The "sqlite3_stmt" structure pointer that is returned by sqlite3_prepare()
+** is really a pointer to an instance of this structure.
+*/
+struct Vdbe {
+  sqlite3 *db;            /* The database connection that owns this statement */
+  Vdbe *pPrev,*pNext;     /* Linked list of VDBEs with the same Vdbe.db */
+  Parse *pParse;          /* Parsing context used to create this Vdbe */
+  ynVar nVar;             /* Number of entries in aVar[] */
+  ynVar nzVar;            /* Number of entries in azVar[] */
+  u32 magic;              /* Magic number for sanity checking */
+  int nMem;               /* Number of memory locations currently allocated */
+  int nCursor;            /* Number of slots in apCsr[] */
+  u32 cacheCtr;           /* VdbeCursor row cache generation counter */
+  int pc;                 /* The program counter */
+  int rc;                 /* Value to return */
+  int nChange;            /* Number of db changes made since last reset */
+  int iStatement;         /* Statement number (or 0 if has not opened stmt) */
+  i64 iCurrentTime;       /* Value of julianday('now') for this statement */
+  i64 nFkConstraint;      /* Number of imm. FK constraints this VM */
+  i64 nStmtDefCons;       /* Number of def. constraints when stmt started */
+  i64 nStmtDefImmCons;    /* Number of def. imm constraints when stmt started */
+
+  /* When allocating a new Vdbe object, all of the fields below should be
+  ** initialized to zero or NULL */
+
+  Op *aOp;                /* Space to hold the virtual machine's program */
+  Mem *aMem;              /* The memory locations */
+  Mem **apArg;            /* Arguments to currently executing user function */
+  Mem *aColName;          /* Column names to return */
+  Mem *pResultSet;        /* Pointer to an array of results */
+  char *zErrMsg;          /* Error message written here */
+  VdbeCursor **apCsr;     /* One element of this array for each open cursor */
+  Mem *aVar;              /* Values for the OP_Variable opcode. */
+  char **azVar;           /* Name of variables */
+#ifndef SQLITE_OMIT_TRACE
+  i64 startTime;          /* Time when query started - used for profiling */
+#endif
+  int nOp;                /* Number of instructions in the program */
+#ifdef SQLITE_DEBUG
+  int rcApp;              /* errcode set by sqlite3_result_error_code() */
+#endif
+  u16 nResColumn;         /* Number of columns in one row of the result set */
+  u8 errorAction;         /* Recovery action to do in case of an error */
+  u8 minWriteFileFormat;  /* Minimum file format for writable database files */
+  bft expired:1;          /* True if the VM needs to be recompiled */
+  bft doingRerun:1;       /* True if rerunning after an auto-reprepare */
+  bft explain:2;          /* True if EXPLAIN present on SQL command */
+  bft changeCntOn:1;      /* True to update the change-counter */
+  bft runOnlyOnce:1;      /* Automatically expire on reset */
+  bft usesStmtJournal:1;  /* True if uses a statement journal */
+  bft readOnly:1;         /* True for statements that do not write */
+  bft bIsReader:1;        /* True for statements that read */
+  bft isPrepareV2:1;      /* True if prepared with prepare_v2() */
+  yDbMask btreeMask;      /* Bitmask of db->aDb[] entries referenced */
+  yDbMask lockMask;       /* Subset of btreeMask that requires a lock */
+  u32 aCounter[5];        /* Counters used by sqlite3_stmt_status() */
+  char *zSql;             /* Text of the SQL statement that generated this */
+  void *pFree;            /* Free this when deleting the vdbe */
+  VdbeFrame *pFrame;      /* Parent frame */
+  VdbeFrame *pDelFrame;   /* List of frame objects to free on VM reset */
+  int nFrame;             /* Number of frames in pFrame list */
+  u32 expmask;            /* Binding to these vars invalidates VM */
+  SubProgram *pProgram;   /* Linked list of all sub-programs used by VM */
+  AuxData *pAuxData;      /* Linked list of auxdata allocations */
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+  i64 *anExec;            /* Number of times each op has been executed */
+  int nScan;              /* Entries in aScan[] */
+  ScanStatus *aScan;      /* Scan definitions for sqlite3_stmt_scanstatus() */
+#endif
+};
+
+/*
+** The following are allowed values for Vdbe.magic
+*/
+#define VDBE_MAGIC_INIT     0x16bceaa5    /* Building a VDBE program */
+#define VDBE_MAGIC_RUN      0x2df20da3    /* VDBE is ready to execute */
+#define VDBE_MAGIC_HALT     0x319c2973    /* VDBE has completed execution */
+#define VDBE_MAGIC_RESET    0x48fa9f76    /* Reset and ready to run again */
+#define VDBE_MAGIC_DEAD     0x5606c3c8    /* The VDBE has been deallocated */
+
+/*
+** Structure used to store the context required by the 
+** sqlite3_preupdate_*() API functions.
+*/
+struct PreUpdate {
+  Vdbe *v;
+  VdbeCursor *pCsr;               /* Cursor to read old values from */
+  int op;                         /* One of SQLITE_INSERT, UPDATE, DELETE */
+  u8 *aRecord;                    /* old.* database record */
+  KeyInfo keyinfo;
+  UnpackedRecord *pUnpacked;      /* Unpacked version of aRecord[] */
+  UnpackedRecord *pNewUnpacked;   /* Unpacked version of new.* record */
+  int iNewReg;                    /* Register for new.* values */
+  i64 iKey1;                      /* First key value passed to hook */
+  i64 iKey2;                      /* Second key value passed to hook */
+  Mem *aNew;                      /* Array of new.* values */
+  Table *pTab;                    /* Schema object being upated */          
+};
+
+/*
+** Function prototypes
+*/
+SQLITE_PRIVATE void sqlite3VdbeError(Vdbe*, const char *, ...);
+SQLITE_PRIVATE void sqlite3VdbeFreeCursor(Vdbe *, VdbeCursor*);
+void sqliteVdbePopStack(Vdbe*,int);
+SQLITE_PRIVATE int sqlite3VdbeCursorMoveto(VdbeCursor**, int*);
+SQLITE_PRIVATE int sqlite3VdbeCursorRestore(VdbeCursor*);
+#if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)
+SQLITE_PRIVATE void sqlite3VdbePrintOp(FILE*, int, Op*);
+#endif
+SQLITE_PRIVATE u32 sqlite3VdbeSerialTypeLen(u32);
+SQLITE_PRIVATE u8 sqlite3VdbeOneByteSerialTypeLen(u8);
+SQLITE_PRIVATE u32 sqlite3VdbeSerialType(Mem*, int, u32*);
+SQLITE_PRIVATE u32 sqlite3VdbeSerialPut(unsigned char*, Mem*, u32);
+SQLITE_PRIVATE u32 sqlite3VdbeSerialGet(const unsigned char*, u32, Mem*);
+SQLITE_PRIVATE void sqlite3VdbeDeleteAuxData(sqlite3*, AuxData**, int, int);
+
+int sqlite2BtreeKeyCompare(BtCursor *, const void *, int, int, int *);
+SQLITE_PRIVATE int sqlite3VdbeIdxKeyCompare(sqlite3*,VdbeCursor*,UnpackedRecord*,int*);
+SQLITE_PRIVATE int sqlite3VdbeIdxRowid(sqlite3*, BtCursor*, i64*);
+SQLITE_PRIVATE int sqlite3VdbeExec(Vdbe*);
+SQLITE_PRIVATE int sqlite3VdbeList(Vdbe*);
+SQLITE_PRIVATE int sqlite3VdbeHalt(Vdbe*);
+SQLITE_PRIVATE int sqlite3VdbeChangeEncoding(Mem *, int);
+SQLITE_PRIVATE int sqlite3VdbeMemTooBig(Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemCopy(Mem*, const Mem*);
+SQLITE_PRIVATE void sqlite3VdbeMemShallowCopy(Mem*, const Mem*, int);
+SQLITE_PRIVATE void sqlite3VdbeMemMove(Mem*, Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemNulTerminate(Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemSetStr(Mem*, const char*, int, u8, void(*)(void*));
+SQLITE_PRIVATE void sqlite3VdbeMemSetInt64(Mem*, i64);
+#ifdef SQLITE_OMIT_FLOATING_POINT
+# define sqlite3VdbeMemSetDouble sqlite3VdbeMemSetInt64
+#else
+SQLITE_PRIVATE   void sqlite3VdbeMemSetDouble(Mem*, double);
+#endif
+SQLITE_PRIVATE void sqlite3VdbeMemInit(Mem*,sqlite3*,u16);
+SQLITE_PRIVATE void sqlite3VdbeMemSetNull(Mem*);
+SQLITE_PRIVATE void sqlite3VdbeMemSetZeroBlob(Mem*,int);
+SQLITE_PRIVATE void sqlite3VdbeMemSetRowSet(Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemMakeWriteable(Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemStringify(Mem*, u8, u8);
+SQLITE_PRIVATE i64 sqlite3VdbeIntValue(Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemIntegerify(Mem*);
+SQLITE_PRIVATE double sqlite3VdbeRealValue(Mem*);
+SQLITE_PRIVATE void sqlite3VdbeIntegerAffinity(Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemRealify(Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemNumerify(Mem*);
+SQLITE_PRIVATE void sqlite3VdbeMemCast(Mem*,u8,u8);
+SQLITE_PRIVATE int sqlite3VdbeMemFromBtree(BtCursor*,u32,u32,int,Mem*);
+SQLITE_PRIVATE void sqlite3VdbeMemRelease(Mem *p);
+SQLITE_PRIVATE int sqlite3VdbeMemFinalize(Mem*, FuncDef*);
+SQLITE_PRIVATE const char *sqlite3OpcodeName(int);
+SQLITE_PRIVATE int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve);
+SQLITE_PRIVATE int sqlite3VdbeMemClearAndResize(Mem *pMem, int n);
+SQLITE_PRIVATE int sqlite3VdbeCloseStatement(Vdbe *, int);
+SQLITE_PRIVATE void sqlite3VdbeFrameDelete(VdbeFrame*);
+SQLITE_PRIVATE int sqlite3VdbeFrameRestore(VdbeFrame *);
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+SQLITE_PRIVATE void sqlite3VdbePreUpdateHook(Vdbe*,VdbeCursor*,int,const char*,Table*,i64,int);
+#endif
+SQLITE_PRIVATE int sqlite3VdbeTransferError(Vdbe *p);
+
+SQLITE_PRIVATE int sqlite3VdbeSorterInit(sqlite3 *, int, VdbeCursor *);
+SQLITE_PRIVATE void sqlite3VdbeSorterReset(sqlite3 *, VdbeSorter *);
+SQLITE_PRIVATE void sqlite3VdbeSorterClose(sqlite3 *, VdbeCursor *);
+SQLITE_PRIVATE int sqlite3VdbeSorterRowkey(const VdbeCursor *, Mem *);
+SQLITE_PRIVATE int sqlite3VdbeSorterNext(sqlite3 *, const VdbeCursor *, int *);
+SQLITE_PRIVATE int sqlite3VdbeSorterRewind(const VdbeCursor *, int *);
+SQLITE_PRIVATE int sqlite3VdbeSorterWrite(const VdbeCursor *, Mem *);
+SQLITE_PRIVATE int sqlite3VdbeSorterCompare(const VdbeCursor *, Mem *, int, int *);
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE) 
+SQLITE_PRIVATE   void sqlite3VdbeEnter(Vdbe*);
+#else
+# define sqlite3VdbeEnter(X)
+#endif
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
+SQLITE_PRIVATE   void sqlite3VdbeLeave(Vdbe*);
+#else
+# define sqlite3VdbeLeave(X)
+#endif
+
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE void sqlite3VdbeMemAboutToChange(Vdbe*,Mem*);
+SQLITE_PRIVATE int sqlite3VdbeCheckMemInvariants(Mem*);
+#endif
+
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+SQLITE_PRIVATE int sqlite3VdbeCheckFk(Vdbe *, int);
+#else
+# define sqlite3VdbeCheckFk(p,i) 0
+#endif
+
+SQLITE_PRIVATE int sqlite3VdbeMemTranslate(Mem*, u8);
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE   void sqlite3VdbePrintSql(Vdbe*);
+SQLITE_PRIVATE   void sqlite3VdbeMemPrettyPrint(Mem *pMem, char *zBuf);
+#endif
+SQLITE_PRIVATE int sqlite3VdbeMemHandleBom(Mem *pMem);
+
+#ifndef SQLITE_OMIT_INCRBLOB
+SQLITE_PRIVATE   int sqlite3VdbeMemExpandBlob(Mem *);
+  #define ExpandBlob(P) (((P)->flags&MEM_Zero)?sqlite3VdbeMemExpandBlob(P):0)
+#else
+  #define sqlite3VdbeMemExpandBlob(x) SQLITE_OK
+  #define ExpandBlob(P) SQLITE_OK
+#endif
+
+#endif /* !defined(SQLITE_VDBEINT_H) */
+
+/************** End of vdbeInt.h *********************************************/
+/************** Continuing where we left off in status.c *********************/
+
+/*
+** Variables in which to record status information.
+*/
+#if SQLITE_PTRSIZE>4
+typedef sqlite3_int64 sqlite3StatValueType;
+#else
+typedef u32 sqlite3StatValueType;
+#endif
+typedef struct sqlite3StatType sqlite3StatType;
+static SQLITE_WSD struct sqlite3StatType {
+  sqlite3StatValueType nowValue[10];  /* Current value */
+  sqlite3StatValueType mxValue[10];   /* Maximum value */
+} sqlite3Stat = { {0,}, {0,} };
+
+/*
+** Elements of sqlite3Stat[] are protected by either the memory allocator
+** mutex, or by the pcache1 mutex.  The following array determines which.
+*/
+static const char statMutex[] = {
+  0,  /* SQLITE_STATUS_MEMORY_USED */
+  1,  /* SQLITE_STATUS_PAGECACHE_USED */
+  1,  /* SQLITE_STATUS_PAGECACHE_OVERFLOW */
+  0,  /* SQLITE_STATUS_SCRATCH_USED */
+  0,  /* SQLITE_STATUS_SCRATCH_OVERFLOW */
+  0,  /* SQLITE_STATUS_MALLOC_SIZE */
+  0,  /* SQLITE_STATUS_PARSER_STACK */
+  1,  /* SQLITE_STATUS_PAGECACHE_SIZE */
+  0,  /* SQLITE_STATUS_SCRATCH_SIZE */
+  0,  /* SQLITE_STATUS_MALLOC_COUNT */
+};
+
+
+/* The "wsdStat" macro will resolve to the status information
+** state vector.  If writable static data is unsupported on the target,
+** we have to locate the state vector at run-time.  In the more common
+** case where writable static data is supported, wsdStat can refer directly
+** to the "sqlite3Stat" state vector declared above.
+*/
+#ifdef SQLITE_OMIT_WSD
+# define wsdStatInit  sqlite3StatType *x = &GLOBAL(sqlite3StatType,sqlite3Stat)
+# define wsdStat x[0]
+#else
+# define wsdStatInit
+# define wsdStat sqlite3Stat
+#endif
+
+/*
+** Return the current value of a status parameter.  The caller must
+** be holding the appropriate mutex.
+*/
+SQLITE_PRIVATE sqlite3_int64 sqlite3StatusValue(int op){
+  wsdStatInit;
+  assert( op>=0 && op<ArraySize(wsdStat.nowValue) );
+  assert( op>=0 && op<ArraySize(statMutex) );
+  assert( sqlite3_mutex_held(statMutex[op] ? sqlite3Pcache1Mutex()
+                                           : sqlite3MallocMutex()) );
+  return wsdStat.nowValue[op];
+}
+
+/*
+** Add N to the value of a status record.  The caller must hold the
+** appropriate mutex.  (Locking is checked by assert()).
+**
+** The StatusUp() routine can accept positive or negative values for N.
+** The value of N is added to the current status value and the high-water
+** mark is adjusted if necessary.
+**
+** The StatusDown() routine lowers the current value by N.  The highwater
+** mark is unchanged.  N must be non-negative for StatusDown().
+*/
+SQLITE_PRIVATE void sqlite3StatusUp(int op, int N){
+  wsdStatInit;
+  assert( op>=0 && op<ArraySize(wsdStat.nowValue) );
+  assert( op>=0 && op<ArraySize(statMutex) );
+  assert( sqlite3_mutex_held(statMutex[op] ? sqlite3Pcache1Mutex()
+                                           : sqlite3MallocMutex()) );
+  wsdStat.nowValue[op] += N;
+  if( wsdStat.nowValue[op]>wsdStat.mxValue[op] ){
+    wsdStat.mxValue[op] = wsdStat.nowValue[op];
+  }
+}
+SQLITE_PRIVATE void sqlite3StatusDown(int op, int N){
+  wsdStatInit;
+  assert( N>=0 );
+  assert( op>=0 && op<ArraySize(statMutex) );
+  assert( sqlite3_mutex_held(statMutex[op] ? sqlite3Pcache1Mutex()
+                                           : sqlite3MallocMutex()) );
+  assert( op>=0 && op<ArraySize(wsdStat.nowValue) );
+  wsdStat.nowValue[op] -= N;
+}
+
+/*
+** Adjust the highwater mark if necessary.
+** The caller must hold the appropriate mutex.
+*/
+SQLITE_PRIVATE void sqlite3StatusHighwater(int op, int X){
+  sqlite3StatValueType newValue;
+  wsdStatInit;
+  assert( X>=0 );
+  newValue = (sqlite3StatValueType)X;
+  assert( op>=0 && op<ArraySize(wsdStat.nowValue) );
+  assert( op>=0 && op<ArraySize(statMutex) );
+  assert( sqlite3_mutex_held(statMutex[op] ? sqlite3Pcache1Mutex()
+                                           : sqlite3MallocMutex()) );
+  assert( op==SQLITE_STATUS_MALLOC_SIZE
+          || op==SQLITE_STATUS_PAGECACHE_SIZE
+          || op==SQLITE_STATUS_SCRATCH_SIZE
+          || op==SQLITE_STATUS_PARSER_STACK );
+  if( newValue>wsdStat.mxValue[op] ){
+    wsdStat.mxValue[op] = newValue;
+  }
+}
+
+/*
+** Query status information.
+*/
+SQLITE_API int sqlite3_status64(
+  int op,
+  sqlite3_int64 *pCurrent,
+  sqlite3_int64 *pHighwater,
+  int resetFlag
+){
+  sqlite3_mutex *pMutex;
+  wsdStatInit;
+  if( op<0 || op>=ArraySize(wsdStat.nowValue) ){
+    return SQLITE_MISUSE_BKPT;
+  }
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( pCurrent==0 || pHighwater==0 ) return SQLITE_MISUSE_BKPT;
+#endif
+  pMutex = statMutex[op] ? sqlite3Pcache1Mutex() : sqlite3MallocMutex();
+  sqlite3_mutex_enter(pMutex);
+  *pCurrent = wsdStat.nowValue[op];
+  *pHighwater = wsdStat.mxValue[op];
+  if( resetFlag ){
+    wsdStat.mxValue[op] = wsdStat.nowValue[op];
+  }
+  sqlite3_mutex_leave(pMutex);
+  (void)pMutex;  /* Prevent warning when SQLITE_THREADSAFE=0 */
+  return SQLITE_OK;
+}
+SQLITE_API int sqlite3_status(int op, int *pCurrent, int *pHighwater, int resetFlag){
+  sqlite3_int64 iCur = 0, iHwtr = 0;
+  int rc;
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( pCurrent==0 || pHighwater==0 ) return SQLITE_MISUSE_BKPT;
+#endif
+  rc = sqlite3_status64(op, &iCur, &iHwtr, resetFlag);
+  if( rc==0 ){
+    *pCurrent = (int)iCur;
+    *pHighwater = (int)iHwtr;
+  }
+  return rc;
+}
+
+/*
+** Query status information for a single database connection
+*/
+SQLITE_API int sqlite3_db_status(
+  sqlite3 *db,          /* The database connection whose status is desired */
+  int op,               /* Status verb */
+  int *pCurrent,        /* Write current value here */
+  int *pHighwater,      /* Write high-water mark here */
+  int resetFlag         /* Reset high-water mark if true */
+){
+  int rc = SQLITE_OK;   /* Return code */
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) || pCurrent==0|| pHighwater==0 ){
+    return SQLITE_MISUSE_BKPT;
+  }
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  switch( op ){
+    case SQLITE_DBSTATUS_LOOKASIDE_USED: {
+      *pCurrent = db->lookaside.nOut;
+      *pHighwater = db->lookaside.mxOut;
+      if( resetFlag ){
+        db->lookaside.mxOut = db->lookaside.nOut;
+      }
+      break;
+    }
+
+    case SQLITE_DBSTATUS_LOOKASIDE_HIT:
+    case SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE:
+    case SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL: {
+      testcase( op==SQLITE_DBSTATUS_LOOKASIDE_HIT );
+      testcase( op==SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE );
+      testcase( op==SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL );
+      assert( (op-SQLITE_DBSTATUS_LOOKASIDE_HIT)>=0 );
+      assert( (op-SQLITE_DBSTATUS_LOOKASIDE_HIT)<3 );
+      *pCurrent = 0;
+      *pHighwater = db->lookaside.anStat[op - SQLITE_DBSTATUS_LOOKASIDE_HIT];
+      if( resetFlag ){
+        db->lookaside.anStat[op - SQLITE_DBSTATUS_LOOKASIDE_HIT] = 0;
+      }
+      break;
+    }
+
+    /* 
+    ** Return an approximation for the amount of memory currently used
+    ** by all pagers associated with the given database connection.  The
+    ** highwater mark is meaningless and is returned as zero.
+    */
+    case SQLITE_DBSTATUS_CACHE_USED_SHARED:
+    case SQLITE_DBSTATUS_CACHE_USED: {
+      int totalUsed = 0;
+      int i;
+      sqlite3BtreeEnterAll(db);
+      for(i=0; i<db->nDb; i++){
+        Btree *pBt = db->aDb[i].pBt;
+        if( pBt ){
+          Pager *pPager = sqlite3BtreePager(pBt);
+          int nByte = sqlite3PagerMemUsed(pPager);
+          if( op==SQLITE_DBSTATUS_CACHE_USED_SHARED ){
+            nByte = nByte / sqlite3BtreeConnectionCount(pBt);
+          }
+          totalUsed += nByte;
+        }
+      }
+      sqlite3BtreeLeaveAll(db);
+      *pCurrent = totalUsed;
+      *pHighwater = 0;
+      break;
+    }
+
+    /*
+    ** *pCurrent gets an accurate estimate of the amount of memory used
+    ** to store the schema for all databases (main, temp, and any ATTACHed
+    ** databases.  *pHighwater is set to zero.
+    */
+    case SQLITE_DBSTATUS_SCHEMA_USED: {
+      int i;                      /* Used to iterate through schemas */
+      int nByte = 0;              /* Used to accumulate return value */
+
+      sqlite3BtreeEnterAll(db);
+      db->pnBytesFreed = &nByte;
+      for(i=0; i<db->nDb; i++){
+        Schema *pSchema = db->aDb[i].pSchema;
+        if( ALWAYS(pSchema!=0) ){
+          HashElem *p;
+
+          nByte += sqlite3GlobalConfig.m.xRoundup(sizeof(HashElem)) * (
+              pSchema->tblHash.count 
+            + pSchema->trigHash.count
+            + pSchema->idxHash.count
+            + pSchema->fkeyHash.count
+          );
+          nByte += sqlite3_msize(pSchema->tblHash.ht);
+          nByte += sqlite3_msize(pSchema->trigHash.ht);
+          nByte += sqlite3_msize(pSchema->idxHash.ht);
+          nByte += sqlite3_msize(pSchema->fkeyHash.ht);
+
+          for(p=sqliteHashFirst(&pSchema->trigHash); p; p=sqliteHashNext(p)){
+            sqlite3DeleteTrigger(db, (Trigger*)sqliteHashData(p));
+          }
+          for(p=sqliteHashFirst(&pSchema->tblHash); p; p=sqliteHashNext(p)){
+            sqlite3DeleteTable(db, (Table *)sqliteHashData(p));
+          }
+        }
+      }
+      db->pnBytesFreed = 0;
+      sqlite3BtreeLeaveAll(db);
+
+      *pHighwater = 0;
+      *pCurrent = nByte;
+      break;
+    }
+
+    /*
+    ** *pCurrent gets an accurate estimate of the amount of memory used
+    ** to store all prepared statements.
+    ** *pHighwater is set to zero.
+    */
+    case SQLITE_DBSTATUS_STMT_USED: {
+      struct Vdbe *pVdbe;         /* Used to iterate through VMs */
+      int nByte = 0;              /* Used to accumulate return value */
+
+      db->pnBytesFreed = &nByte;
+      for(pVdbe=db->pVdbe; pVdbe; pVdbe=pVdbe->pNext){
+        sqlite3VdbeClearObject(db, pVdbe);
+        sqlite3DbFree(db, pVdbe);
+      }
+      db->pnBytesFreed = 0;
+
+      *pHighwater = 0;  /* IMP: R-64479-57858 */
+      *pCurrent = nByte;
+
+      break;
+    }
+
+    /*
+    ** Set *pCurrent to the total cache hits or misses encountered by all
+    ** pagers the database handle is connected to. *pHighwater is always set 
+    ** to zero.
+    */
+    case SQLITE_DBSTATUS_CACHE_HIT:
+    case SQLITE_DBSTATUS_CACHE_MISS:
+    case SQLITE_DBSTATUS_CACHE_WRITE:{
+      int i;
+      int nRet = 0;
+      assert( SQLITE_DBSTATUS_CACHE_MISS==SQLITE_DBSTATUS_CACHE_HIT+1 );
+      assert( SQLITE_DBSTATUS_CACHE_WRITE==SQLITE_DBSTATUS_CACHE_HIT+2 );
+
+      for(i=0; i<db->nDb; i++){
+        if( db->aDb[i].pBt ){
+          Pager *pPager = sqlite3BtreePager(db->aDb[i].pBt);
+          sqlite3PagerCacheStat(pPager, op, resetFlag, &nRet);
+        }
+      }
+      *pHighwater = 0; /* IMP: R-42420-56072 */
+                       /* IMP: R-54100-20147 */
+                       /* IMP: R-29431-39229 */
+      *pCurrent = nRet;
+      break;
+    }
+
+    /* Set *pCurrent to non-zero if there are unresolved deferred foreign
+    ** key constraints.  Set *pCurrent to zero if all foreign key constraints
+    ** have been satisfied.  The *pHighwater is always set to zero.
+    */
+    case SQLITE_DBSTATUS_DEFERRED_FKS: {
+      *pHighwater = 0;  /* IMP: R-11967-56545 */
+      *pCurrent = db->nDeferredImmCons>0 || db->nDeferredCons>0;
+      break;
+    }
+
+    default: {
+      rc = SQLITE_ERROR;
+    }
+  }
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+/************** End of status.c **********************************************/
+/************** Begin file date.c ********************************************/
+/*
+** 2003 October 31
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C functions that implement date and time
+** functions for SQLite.  
+**
+** There is only one exported symbol in this file - the function
+** sqlite3RegisterDateTimeFunctions() found at the bottom of the file.
+** All other code has file scope.
+**
+** SQLite processes all times and dates as julian day numbers.  The
+** dates and times are stored as the number of days since noon
+** in Greenwich on November 24, 4714 B.C. according to the Gregorian
+** calendar system. 
+**
+** 1970-01-01 00:00:00 is JD 2440587.5
+** 2000-01-01 00:00:00 is JD 2451544.5
+**
+** This implementation requires years to be expressed as a 4-digit number
+** which means that only dates between 0000-01-01 and 9999-12-31 can
+** be represented, even though julian day numbers allow a much wider
+** range of dates.
+**
+** The Gregorian calendar system is used for all dates and times,
+** even those that predate the Gregorian calendar.  Historians usually
+** use the julian calendar for dates prior to 1582-10-15 and for some
+** dates afterwards, depending on locale.  Beware of this difference.
+**
+** The conversion algorithms are implemented based on descriptions
+** in the following text:
+**
+**      Jean Meeus
+**      Astronomical Algorithms, 2nd Edition, 1998
+**      ISBM 0-943396-61-1
+**      Willmann-Bell, Inc
+**      Richmond, Virginia (USA)
+*/
+/* #include "sqliteInt.h" */
+/* #include <stdlib.h> */
+/* #include <assert.h> */
+#include <time.h>
+
+#ifndef SQLITE_OMIT_DATETIME_FUNCS
+
+/*
+** The MSVC CRT on Windows CE may not have a localtime() function.
+** So declare a substitute.  The substitute function itself is
+** defined in "os_win.c".
+*/
+#if !defined(SQLITE_OMIT_LOCALTIME) && defined(_WIN32_WCE) && \
+    (!defined(SQLITE_MSVC_LOCALTIME_API) || !SQLITE_MSVC_LOCALTIME_API)
+struct tm *__cdecl localtime(const time_t *);
+#endif
+
+/*
+** A structure for holding a single date and time.
+*/
+typedef struct DateTime DateTime;
+struct DateTime {
+  sqlite3_int64 iJD; /* The julian day number times 86400000 */
+  int Y, M, D;       /* Year, month, and day */
+  int h, m;          /* Hour and minutes */
+  int tz;            /* Timezone offset in minutes */
+  double s;          /* Seconds */
+  char validYMD;     /* True (1) if Y,M,D are valid */
+  char validHMS;     /* True (1) if h,m,s are valid */
+  char validJD;      /* True (1) if iJD is valid */
+  char validTZ;      /* True (1) if tz is valid */
+  char tzSet;        /* Timezone was set explicitly */
+};
+
+
+/*
+** Convert zDate into one or more integers according to the conversion
+** specifier zFormat.
+**
+** zFormat[] contains 4 characters for each integer converted, except for
+** the last integer which is specified by three characters.  The meaning
+** of a four-character format specifiers ABCD is:
+**
+**    A:   number of digits to convert.  Always "2" or "4".
+**    B:   minimum value.  Always "0" or "1".
+**    C:   maximum value, decoded as:
+**           a:  12
+**           b:  14
+**           c:  24
+**           d:  31
+**           e:  59
+**           f:  9999
+**    D:   the separator character, or \000 to indicate this is the
+**         last number to convert.
+**
+** Example:  To translate an ISO-8601 date YYYY-MM-DD, the format would
+** be "40f-21a-20c".  The "40f-" indicates the 4-digit year followed by "-".
+** The "21a-" indicates the 2-digit month followed by "-".  The "20c" indicates
+** the 2-digit day which is the last integer in the set.
+**
+** The function returns the number of successful conversions.
+*/
+static int getDigits(const char *zDate, const char *zFormat, ...){
+  /* The aMx[] array translates the 3rd character of each format
+  ** spec into a max size:    a   b   c   d   e     f */
+  static const u16 aMx[] = { 12, 14, 24, 31, 59, 9999 };
+  va_list ap;
+  int cnt = 0;
+  char nextC;
+  va_start(ap, zFormat);
+  do{
+    char N = zFormat[0] - '0';
+    char min = zFormat[1] - '0';
+    int val = 0;
+    u16 max;
+
+    assert( zFormat[2]>='a' && zFormat[2]<='f' );
+    max = aMx[zFormat[2] - 'a'];
+    nextC = zFormat[3];
+    val = 0;
+    while( N-- ){
+      if( !sqlite3Isdigit(*zDate) ){
+        goto end_getDigits;
+      }
+      val = val*10 + *zDate - '0';
+      zDate++;
+    }
+    if( val<(int)min || val>(int)max || (nextC!=0 && nextC!=*zDate) ){
+      goto end_getDigits;
+    }
+    *va_arg(ap,int*) = val;
+    zDate++;
+    cnt++;
+    zFormat += 4;
+  }while( nextC );
+end_getDigits:
+  va_end(ap);
+  return cnt;
+}
+
+/*
+** Parse a timezone extension on the end of a date-time.
+** The extension is of the form:
+**
+**        (+/-)HH:MM
+**
+** Or the "zulu" notation:
+**
+**        Z
+**
+** If the parse is successful, write the number of minutes
+** of change in p->tz and return 0.  If a parser error occurs,
+** return non-zero.
+**
+** A missing specifier is not considered an error.
+*/
+static int parseTimezone(const char *zDate, DateTime *p){
+  int sgn = 0;
+  int nHr, nMn;
+  int c;
+  while( sqlite3Isspace(*zDate) ){ zDate++; }
+  p->tz = 0;
+  c = *zDate;
+  if( c=='-' ){
+    sgn = -1;
+  }else if( c=='+' ){
+    sgn = +1;
+  }else if( c=='Z' || c=='z' ){
+    zDate++;
+    goto zulu_time;
+  }else{
+    return c!=0;
+  }
+  zDate++;
+  if( getDigits(zDate, "20b:20e", &nHr, &nMn)!=2 ){
+    return 1;
+  }
+  zDate += 5;
+  p->tz = sgn*(nMn + nHr*60);
+zulu_time:
+  while( sqlite3Isspace(*zDate) ){ zDate++; }
+  p->tzSet = 1;
+  return *zDate!=0;
+}
+
+/*
+** Parse times of the form HH:MM or HH:MM:SS or HH:MM:SS.FFFF.
+** The HH, MM, and SS must each be exactly 2 digits.  The
+** fractional seconds FFFF can be one or more digits.
+**
+** Return 1 if there is a parsing error and 0 on success.
+*/
+static int parseHhMmSs(const char *zDate, DateTime *p){
+  int h, m, s;
+  double ms = 0.0;
+  if( getDigits(zDate, "20c:20e", &h, &m)!=2 ){
+    return 1;
+  }
+  zDate += 5;
+  if( *zDate==':' ){
+    zDate++;
+    if( getDigits(zDate, "20e", &s)!=1 ){
+      return 1;
+    }
+    zDate += 2;
+    if( *zDate=='.' && sqlite3Isdigit(zDate[1]) ){
+      double rScale = 1.0;
+      zDate++;
+      while( sqlite3Isdigit(*zDate) ){
+        ms = ms*10.0 + *zDate - '0';
+        rScale *= 10.0;
+        zDate++;
+      }
+      ms /= rScale;
+    }
+  }else{
+    s = 0;
+  }
+  p->validJD = 0;
+  p->validHMS = 1;
+  p->h = h;
+  p->m = m;
+  p->s = s + ms;
+  if( parseTimezone(zDate, p) ) return 1;
+  p->validTZ = (p->tz!=0)?1:0;
+  return 0;
+}
+
+/*
+** Convert from YYYY-MM-DD HH:MM:SS to julian day.  We always assume
+** that the YYYY-MM-DD is according to the Gregorian calendar.
+**
+** Reference:  Meeus page 61
+*/
+static void computeJD(DateTime *p){
+  int Y, M, D, A, B, X1, X2;
+
+  if( p->validJD ) return;
+  if( p->validYMD ){
+    Y = p->Y;
+    M = p->M;
+    D = p->D;
+  }else{
+    Y = 2000;  /* If no YMD specified, assume 2000-Jan-01 */
+    M = 1;
+    D = 1;
+  }
+  if( M<=2 ){
+    Y--;
+    M += 12;
+  }
+  A = Y/100;
+  B = 2 - A + (A/4);
+  X1 = 36525*(Y+4716)/100;
+  X2 = 306001*(M+1)/10000;
+  p->iJD = (sqlite3_int64)((X1 + X2 + D + B - 1524.5 ) * 86400000);
+  p->validJD = 1;
+  if( p->validHMS ){
+    p->iJD += p->h*3600000 + p->m*60000 + (sqlite3_int64)(p->s*1000);
+    if( p->validTZ ){
+      p->iJD -= p->tz*60000;
+      p->validYMD = 0;
+      p->validHMS = 0;
+      p->validTZ = 0;
+    }
+  }
+}
+
+/*
+** Parse dates of the form
+**
+**     YYYY-MM-DD HH:MM:SS.FFF
+**     YYYY-MM-DD HH:MM:SS
+**     YYYY-MM-DD HH:MM
+**     YYYY-MM-DD
+**
+** Write the result into the DateTime structure and return 0
+** on success and 1 if the input string is not a well-formed
+** date.
+*/
+static int parseYyyyMmDd(const char *zDate, DateTime *p){
+  int Y, M, D, neg;
+
+  if( zDate[0]=='-' ){
+    zDate++;
+    neg = 1;
+  }else{
+    neg = 0;
+  }
+  if( getDigits(zDate, "40f-21a-21d", &Y, &M, &D)!=3 ){
+    return 1;
+  }
+  zDate += 10;
+  while( sqlite3Isspace(*zDate) || 'T'==*(u8*)zDate ){ zDate++; }
+  if( parseHhMmSs(zDate, p)==0 ){
+    /* We got the time */
+  }else if( *zDate==0 ){
+    p->validHMS = 0;
+  }else{
+    return 1;
+  }
+  p->validJD = 0;
+  p->validYMD = 1;
+  p->Y = neg ? -Y : Y;
+  p->M = M;
+  p->D = D;
+  if( p->validTZ ){
+    computeJD(p);
+  }
+  return 0;
+}
+
+/*
+** Set the time to the current time reported by the VFS.
+**
+** Return the number of errors.
+*/
+static int setDateTimeToCurrent(sqlite3_context *context, DateTime *p){
+  p->iJD = sqlite3StmtCurrentTime(context);
+  if( p->iJD>0 ){
+    p->validJD = 1;
+    return 0;
+  }else{
+    return 1;
+  }
+}
+
+/*
+** Attempt to parse the given string into a julian day number.  Return
+** the number of errors.
+**
+** The following are acceptable forms for the input string:
+**
+**      YYYY-MM-DD HH:MM:SS.FFF  +/-HH:MM
+**      DDDD.DD 
+**      now
+**
+** In the first form, the +/-HH:MM is always optional.  The fractional
+** seconds extension (the ".FFF") is optional.  The seconds portion
+** (":SS.FFF") is option.  The year and date can be omitted as long
+** as there is a time string.  The time string can be omitted as long
+** as there is a year and date.
+*/
+static int parseDateOrTime(
+  sqlite3_context *context, 
+  const char *zDate, 
+  DateTime *p
+){
+  double r;
+  if( parseYyyyMmDd(zDate,p)==0 ){
+    return 0;
+  }else if( parseHhMmSs(zDate, p)==0 ){
+    return 0;
+  }else if( sqlite3StrICmp(zDate,"now")==0){
+    return setDateTimeToCurrent(context, p);
+  }else if( sqlite3AtoF(zDate, &r, sqlite3Strlen30(zDate), SQLITE_UTF8) ){
+    p->iJD = (sqlite3_int64)(r*86400000.0 + 0.5);
+    p->validJD = 1;
+    return 0;
+  }
+  return 1;
+}
+
+/*
+** Compute the Year, Month, and Day from the julian day number.
+*/
+static void computeYMD(DateTime *p){
+  int Z, A, B, C, D, E, X1;
+  if( p->validYMD ) return;
+  if( !p->validJD ){
+    p->Y = 2000;
+    p->M = 1;
+    p->D = 1;
+  }else{
+    Z = (int)((p->iJD + 43200000)/86400000);
+    A = (int)((Z - 1867216.25)/36524.25);
+    A = Z + 1 + A - (A/4);
+    B = A + 1524;
+    C = (int)((B - 122.1)/365.25);
+    D = (36525*(C&32767))/100;
+    E = (int)((B-D)/30.6001);
+    X1 = (int)(30.6001*E);
+    p->D = B - D - X1;
+    p->M = E<14 ? E-1 : E-13;
+    p->Y = p->M>2 ? C - 4716 : C - 4715;
+  }
+  p->validYMD = 1;
+}
+
+/*
+** Compute the Hour, Minute, and Seconds from the julian day number.
+*/
+static void computeHMS(DateTime *p){
+  int s;
+  if( p->validHMS ) return;
+  computeJD(p);
+  s = (int)((p->iJD + 43200000) % 86400000);
+  p->s = s/1000.0;
+  s = (int)p->s;
+  p->s -= s;
+  p->h = s/3600;
+  s -= p->h*3600;
+  p->m = s/60;
+  p->s += s - p->m*60;
+  p->validHMS = 1;
+}
+
+/*
+** Compute both YMD and HMS
+*/
+static void computeYMD_HMS(DateTime *p){
+  computeYMD(p);
+  computeHMS(p);
+}
+
+/*
+** Clear the YMD and HMS and the TZ
+*/
+static void clearYMD_HMS_TZ(DateTime *p){
+  p->validYMD = 0;
+  p->validHMS = 0;
+  p->validTZ = 0;
+}
+
+#ifndef SQLITE_OMIT_LOCALTIME
+/*
+** On recent Windows platforms, the localtime_s() function is available
+** as part of the "Secure CRT". It is essentially equivalent to 
+** localtime_r() available under most POSIX platforms, except that the 
+** order of the parameters is reversed.
+**
+** See http://msdn.microsoft.com/en-us/library/a442x3ye(VS.80).aspx.
+**
+** If the user has not indicated to use localtime_r() or localtime_s()
+** already, check for an MSVC build environment that provides 
+** localtime_s().
+*/
+#if !HAVE_LOCALTIME_R && !HAVE_LOCALTIME_S \
+    && defined(_MSC_VER) && defined(_CRT_INSECURE_DEPRECATE)
+#undef  HAVE_LOCALTIME_S
+#define HAVE_LOCALTIME_S 1
+#endif
+
+/*
+** The following routine implements the rough equivalent of localtime_r()
+** using whatever operating-system specific localtime facility that
+** is available.  This routine returns 0 on success and
+** non-zero on any kind of error.
+**
+** If the sqlite3GlobalConfig.bLocaltimeFault variable is true then this
+** routine will always fail.
+**
+** EVIDENCE-OF: R-62172-00036 In this implementation, the standard C
+** library function localtime_r() is used to assist in the calculation of
+** local time.
+*/
+static int osLocaltime(time_t *t, struct tm *pTm){
+  int rc;
+#if !HAVE_LOCALTIME_R && !HAVE_LOCALTIME_S
+  struct tm *pX;
+#if SQLITE_THREADSAFE>0
+  sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
+#endif
+  sqlite3_mutex_enter(mutex);
+  pX = localtime(t);
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+  if( sqlite3GlobalConfig.bLocaltimeFault ) pX = 0;
+#endif
+  if( pX ) *pTm = *pX;
+  sqlite3_mutex_leave(mutex);
+  rc = pX==0;
+#else
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+  if( sqlite3GlobalConfig.bLocaltimeFault ) return 1;
+#endif
+#if HAVE_LOCALTIME_R
+  rc = localtime_r(t, pTm)==0;
+#else
+  rc = localtime_s(pTm, t);
+#endif /* HAVE_LOCALTIME_R */
+#endif /* HAVE_LOCALTIME_R || HAVE_LOCALTIME_S */
+  return rc;
+}
+#endif /* SQLITE_OMIT_LOCALTIME */
+
+
+#ifndef SQLITE_OMIT_LOCALTIME
+/*
+** Compute the difference (in milliseconds) between localtime and UTC
+** (a.k.a. GMT) for the time value p where p is in UTC. If no error occurs,
+** return this value and set *pRc to SQLITE_OK. 
+**
+** Or, if an error does occur, set *pRc to SQLITE_ERROR. The returned value
+** is undefined in this case.
+*/
+static sqlite3_int64 localtimeOffset(
+  DateTime *p,                    /* Date at which to calculate offset */
+  sqlite3_context *pCtx,          /* Write error here if one occurs */
+  int *pRc                        /* OUT: Error code. SQLITE_OK or ERROR */
+){
+  DateTime x, y;
+  time_t t;
+  struct tm sLocal;
+
+  /* Initialize the contents of sLocal to avoid a compiler warning. */
+  memset(&sLocal, 0, sizeof(sLocal));
+
+  x = *p;
+  computeYMD_HMS(&x);
+  if( x.Y<1971 || x.Y>=2038 ){
+    /* EVIDENCE-OF: R-55269-29598 The localtime_r() C function normally only
+    ** works for years between 1970 and 2037. For dates outside this range,
+    ** SQLite attempts to map the year into an equivalent year within this
+    ** range, do the calculation, then map the year back.
+    */
+    x.Y = 2000;
+    x.M = 1;
+    x.D = 1;
+    x.h = 0;
+    x.m = 0;
+    x.s = 0.0;
+  } else {
+    int s = (int)(x.s + 0.5);
+    x.s = s;
+  }
+  x.tz = 0;
+  x.validJD = 0;
+  computeJD(&x);
+  t = (time_t)(x.iJD/1000 - 21086676*(i64)10000);
+  if( osLocaltime(&t, &sLocal) ){
+    sqlite3_result_error(pCtx, "local time unavailable", -1);
+    *pRc = SQLITE_ERROR;
+    return 0;
+  }
+  y.Y = sLocal.tm_year + 1900;
+  y.M = sLocal.tm_mon + 1;
+  y.D = sLocal.tm_mday;
+  y.h = sLocal.tm_hour;
+  y.m = sLocal.tm_min;
+  y.s = sLocal.tm_sec;
+  y.validYMD = 1;
+  y.validHMS = 1;
+  y.validJD = 0;
+  y.validTZ = 0;
+  computeJD(&y);
+  *pRc = SQLITE_OK;
+  return y.iJD - x.iJD;
+}
+#endif /* SQLITE_OMIT_LOCALTIME */
+
+/*
+** Process a modifier to a date-time stamp.  The modifiers are
+** as follows:
+**
+**     NNN days
+**     NNN hours
+**     NNN minutes
+**     NNN.NNNN seconds
+**     NNN months
+**     NNN years
+**     start of month
+**     start of year
+**     start of week
+**     start of day
+**     weekday N
+**     unixepoch
+**     localtime
+**     utc
+**
+** Return 0 on success and 1 if there is any kind of error. If the error
+** is in a system call (i.e. localtime()), then an error message is written
+** to context pCtx. If the error is an unrecognized modifier, no error is
+** written to pCtx.
+*/
+static int parseModifier(sqlite3_context *pCtx, const char *zMod, DateTime *p){
+  int rc = 1;
+  int n;
+  double r;
+  char *z, zBuf[30];
+  z = zBuf;
+  for(n=0; n<ArraySize(zBuf)-1 && zMod[n]; n++){
+    z[n] = (char)sqlite3UpperToLower[(u8)zMod[n]];
+  }
+  z[n] = 0;
+  switch( z[0] ){
+#ifndef SQLITE_OMIT_LOCALTIME
+    case 'l': {
+      /*    localtime
+      **
+      ** Assuming the current time value is UTC (a.k.a. GMT), shift it to
+      ** show local time.
+      */
+      if( strcmp(z, "localtime")==0 ){
+        computeJD(p);
+        p->iJD += localtimeOffset(p, pCtx, &rc);
+        clearYMD_HMS_TZ(p);
+      }
+      break;
+    }
+#endif
+    case 'u': {
+      /*
+      **    unixepoch
+      **
+      ** Treat the current value of p->iJD as the number of
+      ** seconds since 1970.  Convert to a real julian day number.
+      */
+      if( strcmp(z, "unixepoch")==0 && p->validJD ){
+        p->iJD = (p->iJD + 43200)/86400 + 21086676*(i64)10000000;
+        clearYMD_HMS_TZ(p);
+        rc = 0;
+      }
+#ifndef SQLITE_OMIT_LOCALTIME
+      else if( strcmp(z, "utc")==0 ){
+        if( p->tzSet==0 ){
+          sqlite3_int64 c1;
+          computeJD(p);
+          c1 = localtimeOffset(p, pCtx, &rc);
+          if( rc==SQLITE_OK ){
+            p->iJD -= c1;
+            clearYMD_HMS_TZ(p);
+            p->iJD += c1 - localtimeOffset(p, pCtx, &rc);
+          }
+          p->tzSet = 1;
+        }else{
+          rc = SQLITE_OK;
+        }
+      }
+#endif
+      break;
+    }
+    case 'w': {
+      /*
+      **    weekday N
+      **
+      ** Move the date to the same time on the next occurrence of
+      ** weekday N where 0==Sunday, 1==Monday, and so forth.  If the
+      ** date is already on the appropriate weekday, this is a no-op.
+      */
+      if( strncmp(z, "weekday ", 8)==0
+               && sqlite3AtoF(&z[8], &r, sqlite3Strlen30(&z[8]), SQLITE_UTF8)
+               && (n=(int)r)==r && n>=0 && r<7 ){
+        sqlite3_int64 Z;
+        computeYMD_HMS(p);
+        p->validTZ = 0;
+        p->validJD = 0;
+        computeJD(p);
+        Z = ((p->iJD + 129600000)/86400000) % 7;
+        if( Z>n ) Z -= 7;
+        p->iJD += (n - Z)*86400000;
+        clearYMD_HMS_TZ(p);
+        rc = 0;
+      }
+      break;
+    }
+    case 's': {
+      /*
+      **    start of TTTTT
+      **
+      ** Move the date backwards to the beginning of the current day,
+      ** or month or year.
+      */
+      if( strncmp(z, "start of ", 9)!=0 ) break;
+      z += 9;
+      computeYMD(p);
+      p->validHMS = 1;
+      p->h = p->m = 0;
+      p->s = 0.0;
+      p->validTZ = 0;
+      p->validJD = 0;
+      if( strcmp(z,"month")==0 ){
+        p->D = 1;
+        rc = 0;
+      }else if( strcmp(z,"year")==0 ){
+        computeYMD(p);
+        p->M = 1;
+        p->D = 1;
+        rc = 0;
+      }else if( strcmp(z,"day")==0 ){
+        rc = 0;
+      }
+      break;
+    }
+    case '+':
+    case '-':
+    case '0':
+    case '1':
+    case '2':
+    case '3':
+    case '4':
+    case '5':
+    case '6':
+    case '7':
+    case '8':
+    case '9': {
+      double rRounder;
+      for(n=1; z[n] && z[n]!=':' && !sqlite3Isspace(z[n]); n++){}
+      if( !sqlite3AtoF(z, &r, n, SQLITE_UTF8) ){
+        rc = 1;
+        break;
+      }
+      if( z[n]==':' ){
+        /* A modifier of the form (+|-)HH:MM:SS.FFF adds (or subtracts) the
+        ** specified number of hours, minutes, seconds, and fractional seconds
+        ** to the time.  The ".FFF" may be omitted.  The ":SS.FFF" may be
+        ** omitted.
+        */
+        const char *z2 = z;
+        DateTime tx;
+        sqlite3_int64 day;
+        if( !sqlite3Isdigit(*z2) ) z2++;
+        memset(&tx, 0, sizeof(tx));
+        if( parseHhMmSs(z2, &tx) ) break;
+        computeJD(&tx);
+        tx.iJD -= 43200000;
+        day = tx.iJD/86400000;
+        tx.iJD -= day*86400000;
+        if( z[0]=='-' ) tx.iJD = -tx.iJD;
+        computeJD(p);
+        clearYMD_HMS_TZ(p);
+        p->iJD += tx.iJD;
+        rc = 0;
+        break;
+      }
+      z += n;
+      while( sqlite3Isspace(*z) ) z++;
+      n = sqlite3Strlen30(z);
+      if( n>10 || n<3 ) break;
+      if( z[n-1]=='s' ){ z[n-1] = 0; n--; }
+      computeJD(p);
+      rc = 0;
+      rRounder = r<0 ? -0.5 : +0.5;
+      if( n==3 && strcmp(z,"day")==0 ){
+        p->iJD += (sqlite3_int64)(r*86400000.0 + rRounder);
+      }else if( n==4 && strcmp(z,"hour")==0 ){
+        p->iJD += (sqlite3_int64)(r*(86400000.0/24.0) + rRounder);
+      }else if( n==6 && strcmp(z,"minute")==0 ){
+        p->iJD += (sqlite3_int64)(r*(86400000.0/(24.0*60.0)) + rRounder);
+      }else if( n==6 && strcmp(z,"second")==0 ){
+        p->iJD += (sqlite3_int64)(r*(86400000.0/(24.0*60.0*60.0)) + rRounder);
+      }else if( n==5 && strcmp(z,"month")==0 ){
+        int x, y;
+        computeYMD_HMS(p);
+        p->M += (int)r;
+        x = p->M>0 ? (p->M-1)/12 : (p->M-12)/12;
+        p->Y += x;
+        p->M -= x*12;
+        p->validJD = 0;
+        computeJD(p);
+        y = (int)r;
+        if( y!=r ){
+          p->iJD += (sqlite3_int64)((r - y)*30.0*86400000.0 + rRounder);
+        }
+      }else if( n==4 && strcmp(z,"year")==0 ){
+        int y = (int)r;
+        computeYMD_HMS(p);
+        p->Y += y;
+        p->validJD = 0;
+        computeJD(p);
+        if( y!=r ){
+          p->iJD += (sqlite3_int64)((r - y)*365.0*86400000.0 + rRounder);
+        }
+      }else{
+        rc = 1;
+      }
+      clearYMD_HMS_TZ(p);
+      break;
+    }
+    default: {
+      break;
+    }
+  }
+  return rc;
+}
+
+/*
+** Process time function arguments.  argv[0] is a date-time stamp.
+** argv[1] and following are modifiers.  Parse them all and write
+** the resulting time into the DateTime structure p.  Return 0
+** on success and 1 if there are any errors.
+**
+** If there are zero parameters (if even argv[0] is undefined)
+** then assume a default value of "now" for argv[0].
+*/
+static int isDate(
+  sqlite3_context *context, 
+  int argc, 
+  sqlite3_value **argv, 
+  DateTime *p
+){
+  int i;
+  const unsigned char *z;
+  int eType;
+  memset(p, 0, sizeof(*p));
+  if( argc==0 ){
+    return setDateTimeToCurrent(context, p);
+  }
+  if( (eType = sqlite3_value_type(argv[0]))==SQLITE_FLOAT
+                   || eType==SQLITE_INTEGER ){
+    p->iJD = (sqlite3_int64)(sqlite3_value_double(argv[0])*86400000.0 + 0.5);
+    p->validJD = 1;
+  }else{
+    z = sqlite3_value_text(argv[0]);
+    if( !z || parseDateOrTime(context, (char*)z, p) ){
+      return 1;
+    }
+  }
+  for(i=1; i<argc; i++){
+    z = sqlite3_value_text(argv[i]);
+    if( z==0 || parseModifier(context, (char*)z, p) ) return 1;
+  }
+  return 0;
+}
+
+
+/*
+** The following routines implement the various date and time functions
+** of SQLite.
+*/
+
+/*
+**    julianday( TIMESTRING, MOD, MOD, ...)
+**
+** Return the julian day number of the date specified in the arguments
+*/
+static void juliandayFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  DateTime x;
+  if( isDate(context, argc, argv, &x)==0 ){
+    computeJD(&x);
+    sqlite3_result_double(context, x.iJD/86400000.0);
+  }
+}
+
+/*
+**    datetime( TIMESTRING, MOD, MOD, ...)
+**
+** Return YYYY-MM-DD HH:MM:SS
+*/
+static void datetimeFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  DateTime x;
+  if( isDate(context, argc, argv, &x)==0 ){
+    char zBuf[100];
+    computeYMD_HMS(&x);
+    sqlite3_snprintf(sizeof(zBuf), zBuf, "%04d-%02d-%02d %02d:%02d:%02d",
+                     x.Y, x.M, x.D, x.h, x.m, (int)(x.s));
+    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
+  }
+}
+
+/*
+**    time( TIMESTRING, MOD, MOD, ...)
+**
+** Return HH:MM:SS
+*/
+static void timeFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  DateTime x;
+  if( isDate(context, argc, argv, &x)==0 ){
+    char zBuf[100];
+    computeHMS(&x);
+    sqlite3_snprintf(sizeof(zBuf), zBuf, "%02d:%02d:%02d", x.h, x.m, (int)x.s);
+    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
+  }
+}
+
+/*
+**    date( TIMESTRING, MOD, MOD, ...)
+**
+** Return YYYY-MM-DD
+*/
+static void dateFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  DateTime x;
+  if( isDate(context, argc, argv, &x)==0 ){
+    char zBuf[100];
+    computeYMD(&x);
+    sqlite3_snprintf(sizeof(zBuf), zBuf, "%04d-%02d-%02d", x.Y, x.M, x.D);
+    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
+  }
+}
+
+/*
+**    strftime( FORMAT, TIMESTRING, MOD, MOD, ...)
+**
+** Return a string described by FORMAT.  Conversions as follows:
+**
+**   %d  day of month
+**   %f  ** fractional seconds  SS.SSS
+**   %H  hour 00-24
+**   %j  day of year 000-366
+**   %J  ** julian day number
+**   %m  month 01-12
+**   %M  minute 00-59
+**   %s  seconds since 1970-01-01
+**   %S  seconds 00-59
+**   %w  day of week 0-6  sunday==0
+**   %W  week of year 00-53
+**   %Y  year 0000-9999
+**   %%  %
+*/
+static void strftimeFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  DateTime x;
+  u64 n;
+  size_t i,j;
+  char *z;
+  sqlite3 *db;
+  const char *zFmt;
+  char zBuf[100];
+  if( argc==0 ) return;
+  zFmt = (const char*)sqlite3_value_text(argv[0]);
+  if( zFmt==0 || isDate(context, argc-1, argv+1, &x) ) return;
+  db = sqlite3_context_db_handle(context);
+  for(i=0, n=1; zFmt[i]; i++, n++){
+    if( zFmt[i]=='%' ){
+      switch( zFmt[i+1] ){
+        case 'd':
+        case 'H':
+        case 'm':
+        case 'M':
+        case 'S':
+        case 'W':
+          n++;
+          /* fall thru */
+        case 'w':
+        case '%':
+          break;
+        case 'f':
+          n += 8;
+          break;
+        case 'j':
+          n += 3;
+          break;
+        case 'Y':
+          n += 8;
+          break;
+        case 's':
+        case 'J':
+          n += 50;
+          break;
+        default:
+          return;  /* ERROR.  return a NULL */
+      }
+      i++;
+    }
+  }
+  testcase( n==sizeof(zBuf)-1 );
+  testcase( n==sizeof(zBuf) );
+  testcase( n==(u64)db->aLimit[SQLITE_LIMIT_LENGTH]+1 );
+  testcase( n==(u64)db->aLimit[SQLITE_LIMIT_LENGTH] );
+  if( n<sizeof(zBuf) ){
+    z = zBuf;
+  }else if( n>(u64)db->aLimit[SQLITE_LIMIT_LENGTH] ){
+    sqlite3_result_error_toobig(context);
+    return;
+  }else{
+    z = sqlite3DbMallocRawNN(db, (int)n);
+    if( z==0 ){
+      sqlite3_result_error_nomem(context);
+      return;
+    }
+  }
+  computeJD(&x);
+  computeYMD_HMS(&x);
+  for(i=j=0; zFmt[i]; i++){
+    if( zFmt[i]!='%' ){
+      z[j++] = zFmt[i];
+    }else{
+      i++;
+      switch( zFmt[i] ){
+        case 'd':  sqlite3_snprintf(3, &z[j],"%02d",x.D); j+=2; break;
+        case 'f': {
+          double s = x.s;
+          if( s>59.999 ) s = 59.999;
+          sqlite3_snprintf(7, &z[j],"%06.3f", s);
+          j += sqlite3Strlen30(&z[j]);
+          break;
+        }
+        case 'H':  sqlite3_snprintf(3, &z[j],"%02d",x.h); j+=2; break;
+        case 'W': /* Fall thru */
+        case 'j': {
+          int nDay;             /* Number of days since 1st day of year */
+          DateTime y = x;
+          y.validJD = 0;
+          y.M = 1;
+          y.D = 1;
+          computeJD(&y);
+          nDay = (int)((x.iJD-y.iJD+43200000)/86400000);
+          if( zFmt[i]=='W' ){
+            int wd;   /* 0=Monday, 1=Tuesday, ... 6=Sunday */
+            wd = (int)(((x.iJD+43200000)/86400000)%7);
+            sqlite3_snprintf(3, &z[j],"%02d",(nDay+7-wd)/7);
+            j += 2;
+          }else{
+            sqlite3_snprintf(4, &z[j],"%03d",nDay+1);
+            j += 3;
+          }
+          break;
+        }
+        case 'J': {
+          sqlite3_snprintf(20, &z[j],"%.16g",x.iJD/86400000.0);
+          j+=sqlite3Strlen30(&z[j]);
+          break;
+        }
+        case 'm':  sqlite3_snprintf(3, &z[j],"%02d",x.M); j+=2; break;
+        case 'M':  sqlite3_snprintf(3, &z[j],"%02d",x.m); j+=2; break;
+        case 's': {
+          sqlite3_snprintf(30,&z[j],"%lld",
+                           (i64)(x.iJD/1000 - 21086676*(i64)10000));
+          j += sqlite3Strlen30(&z[j]);
+          break;
+        }
+        case 'S':  sqlite3_snprintf(3,&z[j],"%02d",(int)x.s); j+=2; break;
+        case 'w': {
+          z[j++] = (char)(((x.iJD+129600000)/86400000) % 7) + '0';
+          break;
+        }
+        case 'Y': {
+          sqlite3_snprintf(5,&z[j],"%04d",x.Y); j+=sqlite3Strlen30(&z[j]);
+          break;
+        }
+        default:   z[j++] = '%'; break;
+      }
+    }
+  }
+  z[j] = 0;
+  sqlite3_result_text(context, z, -1,
+                      z==zBuf ? SQLITE_TRANSIENT : SQLITE_DYNAMIC);
+}
+
+/*
+** current_time()
+**
+** This function returns the same value as time('now').
+*/
+static void ctimeFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **NotUsed2
+){
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  timeFunc(context, 0, 0);
+}
+
+/*
+** current_date()
+**
+** This function returns the same value as date('now').
+*/
+static void cdateFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **NotUsed2
+){
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  dateFunc(context, 0, 0);
+}
+
+/*
+** current_timestamp()
+**
+** This function returns the same value as datetime('now').
+*/
+static void ctimestampFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **NotUsed2
+){
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  datetimeFunc(context, 0, 0);
+}
+#endif /* !defined(SQLITE_OMIT_DATETIME_FUNCS) */
+
+#ifdef SQLITE_OMIT_DATETIME_FUNCS
+/*
+** If the library is compiled to omit the full-scale date and time
+** handling (to get a smaller binary), the following minimal version
+** of the functions current_time(), current_date() and current_timestamp()
+** are included instead. This is to support column declarations that
+** include "DEFAULT CURRENT_TIME" etc.
+**
+** This function uses the C-library functions time(), gmtime()
+** and strftime(). The format string to pass to strftime() is supplied
+** as the user-data for the function.
+*/
+static void currentTimeFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  time_t t;
+  char *zFormat = (char *)sqlite3_user_data(context);
+  sqlite3_int64 iT;
+  struct tm *pTm;
+  struct tm sNow;
+  char zBuf[20];
+
+  UNUSED_PARAMETER(argc);
+  UNUSED_PARAMETER(argv);
+
+  iT = sqlite3StmtCurrentTime(context);
+  if( iT<=0 ) return;
+  t = iT/1000 - 10000*(sqlite3_int64)21086676;
+#if HAVE_GMTIME_R
+  pTm = gmtime_r(&t, &sNow);
+#else
+  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+  pTm = gmtime(&t);
+  if( pTm ) memcpy(&sNow, pTm, sizeof(sNow));
+  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+#endif
+  if( pTm ){
+    strftime(zBuf, 20, zFormat, &sNow);
+    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
+  }
+}
+#endif
+
+/*
+** This function registered all of the above C functions as SQL
+** functions.  This should be the only routine in this file with
+** external linkage.
+*/
+SQLITE_PRIVATE void sqlite3RegisterDateTimeFunctions(void){
+  static FuncDef aDateTimeFuncs[] = {
+#ifndef SQLITE_OMIT_DATETIME_FUNCS
+    DFUNCTION(julianday,        -1, 0, 0, juliandayFunc ),
+    DFUNCTION(date,             -1, 0, 0, dateFunc      ),
+    DFUNCTION(time,             -1, 0, 0, timeFunc      ),
+    DFUNCTION(datetime,         -1, 0, 0, datetimeFunc  ),
+    DFUNCTION(strftime,         -1, 0, 0, strftimeFunc  ),
+    DFUNCTION(current_time,      0, 0, 0, ctimeFunc     ),
+    DFUNCTION(current_timestamp, 0, 0, 0, ctimestampFunc),
+    DFUNCTION(current_date,      0, 0, 0, cdateFunc     ),
+#else
+    STR_FUNCTION(current_time,      0, "%H:%M:%S",          0, currentTimeFunc),
+    STR_FUNCTION(current_date,      0, "%Y-%m-%d",          0, currentTimeFunc),
+    STR_FUNCTION(current_timestamp, 0, "%Y-%m-%d %H:%M:%S", 0, currentTimeFunc),
+#endif
+  };
+  sqlite3InsertBuiltinFuncs(aDateTimeFuncs, ArraySize(aDateTimeFuncs));
+}
+
+/************** End of date.c ************************************************/
+/************** Begin file os.c **********************************************/
+/*
+** 2005 November 29
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains OS interface code that is common to all
+** architectures.
+*/
+/* #include "sqliteInt.h" */
+
+/*
+** If we compile with the SQLITE_TEST macro set, then the following block
+** of code will give us the ability to simulate a disk I/O error.  This
+** is used for testing the I/O recovery logic.
+*/
+#if defined(SQLITE_TEST)
+SQLITE_API int sqlite3_io_error_hit = 0;            /* Total number of I/O Errors */
+SQLITE_API int sqlite3_io_error_hardhit = 0;        /* Number of non-benign errors */
+SQLITE_API int sqlite3_io_error_pending = 0;        /* Count down to first I/O error */
+SQLITE_API int sqlite3_io_error_persist = 0;        /* True if I/O errors persist */
+SQLITE_API int sqlite3_io_error_benign = 0;         /* True if errors are benign */
+SQLITE_API int sqlite3_diskfull_pending = 0;
+SQLITE_API int sqlite3_diskfull = 0;
+#endif /* defined(SQLITE_TEST) */
+
+/*
+** When testing, also keep a count of the number of open files.
+*/
+#if defined(SQLITE_TEST)
+SQLITE_API int sqlite3_open_file_count = 0;
+#endif /* defined(SQLITE_TEST) */
+
+/*
+** The default SQLite sqlite3_vfs implementations do not allocate
+** memory (actually, os_unix.c allocates a small amount of memory
+** from within OsOpen()), but some third-party implementations may.
+** So we test the effects of a malloc() failing and the sqlite3OsXXX()
+** function returning SQLITE_IOERR_NOMEM using the DO_OS_MALLOC_TEST macro.
+**
+** The following functions are instrumented for malloc() failure
+** testing:
+**
+**     sqlite3OsRead()
+**     sqlite3OsWrite()
+**     sqlite3OsSync()
+**     sqlite3OsFileSize()
+**     sqlite3OsLock()
+**     sqlite3OsCheckReservedLock()
+**     sqlite3OsFileControl()
+**     sqlite3OsShmMap()
+**     sqlite3OsOpen()
+**     sqlite3OsDelete()
+**     sqlite3OsAccess()
+**     sqlite3OsFullPathname()
+**
+*/
+#if defined(SQLITE_TEST)
+SQLITE_API int sqlite3_memdebug_vfs_oom_test = 1;
+  #define DO_OS_MALLOC_TEST(x)                                       \
+  if (sqlite3_memdebug_vfs_oom_test && (!x || !sqlite3JournalIsInMemory(x))) { \
+    void *pTstAlloc = sqlite3Malloc(10);                             \
+    if (!pTstAlloc) return SQLITE_IOERR_NOMEM_BKPT;                  \
+    sqlite3_free(pTstAlloc);                                         \
+  }
+#else
+  #define DO_OS_MALLOC_TEST(x)
+#endif
+
+/*
+** The following routines are convenience wrappers around methods
+** of the sqlite3_file object.  This is mostly just syntactic sugar. All
+** of this would be completely automatic if SQLite were coded using
+** C++ instead of plain old C.
+*/
+SQLITE_PRIVATE void sqlite3OsClose(sqlite3_file *pId){
+  if( pId->pMethods ){
+    pId->pMethods->xClose(pId);
+    pId->pMethods = 0;
+  }
+}
+SQLITE_PRIVATE int sqlite3OsRead(sqlite3_file *id, void *pBuf, int amt, i64 offset){
+  DO_OS_MALLOC_TEST(id);
+  return id->pMethods->xRead(id, pBuf, amt, offset);
+}
+SQLITE_PRIVATE int sqlite3OsWrite(sqlite3_file *id, const void *pBuf, int amt, i64 offset){
+  DO_OS_MALLOC_TEST(id);
+  return id->pMethods->xWrite(id, pBuf, amt, offset);
+}
+SQLITE_PRIVATE int sqlite3OsTruncate(sqlite3_file *id, i64 size){
+  return id->pMethods->xTruncate(id, size);
+}
+SQLITE_PRIVATE int sqlite3OsSync(sqlite3_file *id, int flags){
+  DO_OS_MALLOC_TEST(id);
+  return id->pMethods->xSync(id, flags);
+}
+SQLITE_PRIVATE int sqlite3OsFileSize(sqlite3_file *id, i64 *pSize){
+  DO_OS_MALLOC_TEST(id);
+  return id->pMethods->xFileSize(id, pSize);
+}
+SQLITE_PRIVATE int sqlite3OsLock(sqlite3_file *id, int lockType){
+  DO_OS_MALLOC_TEST(id);
+  return id->pMethods->xLock(id, lockType);
+}
+SQLITE_PRIVATE int sqlite3OsUnlock(sqlite3_file *id, int lockType){
+  return id->pMethods->xUnlock(id, lockType);
+}
+SQLITE_PRIVATE int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut){
+  DO_OS_MALLOC_TEST(id);
+  return id->pMethods->xCheckReservedLock(id, pResOut);
+}
+
+/*
+** Use sqlite3OsFileControl() when we are doing something that might fail
+** and we need to know about the failures.  Use sqlite3OsFileControlHint()
+** when simply tossing information over the wall to the VFS and we do not
+** really care if the VFS receives and understands the information since it
+** is only a hint and can be safely ignored.  The sqlite3OsFileControlHint()
+** routine has no return value since the return value would be meaningless.
+*/
+SQLITE_PRIVATE int sqlite3OsFileControl(sqlite3_file *id, int op, void *pArg){
+#ifdef SQLITE_TEST
+  if( op!=SQLITE_FCNTL_COMMIT_PHASETWO ){
+    /* Faults are not injected into COMMIT_PHASETWO because, assuming SQLite
+    ** is using a regular VFS, it is called after the corresponding
+    ** transaction has been committed. Injecting a fault at this point
+    ** confuses the test scripts - the COMMIT comand returns SQLITE_NOMEM
+    ** but the transaction is committed anyway.
+    **
+    ** The core must call OsFileControl() though, not OsFileControlHint(),
+    ** as if a custom VFS (e.g. zipvfs) returns an error here, it probably
+    ** means the commit really has failed and an error should be returned
+    ** to the user.  */
+    DO_OS_MALLOC_TEST(id);
+  }
+#endif
+  return id->pMethods->xFileControl(id, op, pArg);
+}
+SQLITE_PRIVATE void sqlite3OsFileControlHint(sqlite3_file *id, int op, void *pArg){
+  (void)id->pMethods->xFileControl(id, op, pArg);
+}
+
+SQLITE_PRIVATE int sqlite3OsSectorSize(sqlite3_file *id){
+  int (*xSectorSize)(sqlite3_file*) = id->pMethods->xSectorSize;
+  return (xSectorSize ? xSectorSize(id) : SQLITE_DEFAULT_SECTOR_SIZE);
+}
+SQLITE_PRIVATE int sqlite3OsDeviceCharacteristics(sqlite3_file *id){
+  return id->pMethods->xDeviceCharacteristics(id);
+}
+SQLITE_PRIVATE int sqlite3OsShmLock(sqlite3_file *id, int offset, int n, int flags){
+  return id->pMethods->xShmLock(id, offset, n, flags);
+}
+SQLITE_PRIVATE void sqlite3OsShmBarrier(sqlite3_file *id){
+  id->pMethods->xShmBarrier(id);
+}
+SQLITE_PRIVATE int sqlite3OsShmUnmap(sqlite3_file *id, int deleteFlag){
+  return id->pMethods->xShmUnmap(id, deleteFlag);
+}
+SQLITE_PRIVATE int sqlite3OsShmMap(
+  sqlite3_file *id,               /* Database file handle */
+  int iPage,
+  int pgsz,
+  int bExtend,                    /* True to extend file if necessary */
+  void volatile **pp              /* OUT: Pointer to mapping */
+){
+  DO_OS_MALLOC_TEST(id);
+  return id->pMethods->xShmMap(id, iPage, pgsz, bExtend, pp);
+}
+
+#if SQLITE_MAX_MMAP_SIZE>0
+/* The real implementation of xFetch and xUnfetch */
+SQLITE_PRIVATE int sqlite3OsFetch(sqlite3_file *id, i64 iOff, int iAmt, void **pp){
+  DO_OS_MALLOC_TEST(id);
+  return id->pMethods->xFetch(id, iOff, iAmt, pp);
+}
+SQLITE_PRIVATE int sqlite3OsUnfetch(sqlite3_file *id, i64 iOff, void *p){
+  return id->pMethods->xUnfetch(id, iOff, p);
+}
+#else
+/* No-op stubs to use when memory-mapped I/O is disabled */
+SQLITE_PRIVATE int sqlite3OsFetch(sqlite3_file *id, i64 iOff, int iAmt, void **pp){
+  *pp = 0;
+  return SQLITE_OK;
+}
+SQLITE_PRIVATE int sqlite3OsUnfetch(sqlite3_file *id, i64 iOff, void *p){
+  return SQLITE_OK;
+}
+#endif
+
+/*
+** The next group of routines are convenience wrappers around the
+** VFS methods.
+*/
+SQLITE_PRIVATE int sqlite3OsOpen(
+  sqlite3_vfs *pVfs,
+  const char *zPath,
+  sqlite3_file *pFile,
+  int flags,
+  int *pFlagsOut
+){
+  int rc;
+  DO_OS_MALLOC_TEST(0);
+  /* 0x87f7f is a mask of SQLITE_OPEN_ flags that are valid to be passed
+  ** down into the VFS layer.  Some SQLITE_OPEN_ flags (for example,
+  ** SQLITE_OPEN_FULLMUTEX or SQLITE_OPEN_SHAREDCACHE) are blocked before
+  ** reaching the VFS. */
+  rc = pVfs->xOpen(pVfs, zPath, pFile, flags & 0x87f7f, pFlagsOut);
+  assert( rc==SQLITE_OK || pFile->pMethods==0 );
+  return rc;
+}
+SQLITE_PRIVATE int sqlite3OsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
+  DO_OS_MALLOC_TEST(0);
+  assert( dirSync==0 || dirSync==1 );
+  return pVfs->xDelete(pVfs, zPath, dirSync);
+}
+SQLITE_PRIVATE int sqlite3OsAccess(
+  sqlite3_vfs *pVfs,
+  const char *zPath,
+  int flags,
+  int *pResOut
+){
+  DO_OS_MALLOC_TEST(0);
+  return pVfs->xAccess(pVfs, zPath, flags, pResOut);
+}
+SQLITE_PRIVATE int sqlite3OsFullPathname(
+  sqlite3_vfs *pVfs,
+  const char *zPath,
+  int nPathOut,
+  char *zPathOut
+){
+  DO_OS_MALLOC_TEST(0);
+  zPathOut[0] = 0;
+  return pVfs->xFullPathname(pVfs, zPath, nPathOut, zPathOut);
+}
+#ifndef SQLITE_OMIT_LOAD_EXTENSION
+SQLITE_PRIVATE void *sqlite3OsDlOpen(sqlite3_vfs *pVfs, const char *zPath){
+  return pVfs->xDlOpen(pVfs, zPath);
+}
+SQLITE_PRIVATE void sqlite3OsDlError(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
+  pVfs->xDlError(pVfs, nByte, zBufOut);
+}
+SQLITE_PRIVATE void (*sqlite3OsDlSym(sqlite3_vfs *pVfs, void *pHdle, const char *zSym))(void){
+  return pVfs->xDlSym(pVfs, pHdle, zSym);
+}
+SQLITE_PRIVATE void sqlite3OsDlClose(sqlite3_vfs *pVfs, void *pHandle){
+  pVfs->xDlClose(pVfs, pHandle);
+}
+#endif /* SQLITE_OMIT_LOAD_EXTENSION */
+SQLITE_PRIVATE int sqlite3OsRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
+  return pVfs->xRandomness(pVfs, nByte, zBufOut);
+}
+SQLITE_PRIVATE int sqlite3OsSleep(sqlite3_vfs *pVfs, int nMicro){
+  return pVfs->xSleep(pVfs, nMicro);
+}
+SQLITE_PRIVATE int sqlite3OsGetLastError(sqlite3_vfs *pVfs){
+  return pVfs->xGetLastError ? pVfs->xGetLastError(pVfs, 0, 0) : 0;
+}
+SQLITE_PRIVATE int sqlite3OsCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *pTimeOut){
+  int rc;
+  /* IMPLEMENTATION-OF: R-49045-42493 SQLite will use the xCurrentTimeInt64()
+  ** method to get the current date and time if that method is available
+  ** (if iVersion is 2 or greater and the function pointer is not NULL) and
+  ** will fall back to xCurrentTime() if xCurrentTimeInt64() is
+  ** unavailable.
+  */
+  if( pVfs->iVersion>=2 && pVfs->xCurrentTimeInt64 ){
+    rc = pVfs->xCurrentTimeInt64(pVfs, pTimeOut);
+  }else{
+    double r;
+    rc = pVfs->xCurrentTime(pVfs, &r);
+    *pTimeOut = (sqlite3_int64)(r*86400000.0);
+  }
+  return rc;
+}
+
+SQLITE_PRIVATE int sqlite3OsOpenMalloc(
+  sqlite3_vfs *pVfs,
+  const char *zFile,
+  sqlite3_file **ppFile,
+  int flags,
+  int *pOutFlags
+){
+  int rc;
+  sqlite3_file *pFile;
+  pFile = (sqlite3_file *)sqlite3MallocZero(pVfs->szOsFile);
+  if( pFile ){
+    rc = sqlite3OsOpen(pVfs, zFile, pFile, flags, pOutFlags);
+    if( rc!=SQLITE_OK ){
+      sqlite3_free(pFile);
+    }else{
+      *ppFile = pFile;
+    }
+  }else{
+    rc = SQLITE_NOMEM_BKPT;
+  }
+  return rc;
+}
+SQLITE_PRIVATE void sqlite3OsCloseFree(sqlite3_file *pFile){
+  assert( pFile );
+  sqlite3OsClose(pFile);
+  sqlite3_free(pFile);
+}
+
+/*
+** This function is a wrapper around the OS specific implementation of
+** sqlite3_os_init(). The purpose of the wrapper is to provide the
+** ability to simulate a malloc failure, so that the handling of an
+** error in sqlite3_os_init() by the upper layers can be tested.
+*/
+SQLITE_PRIVATE int sqlite3OsInit(void){
+  void *p = sqlite3_malloc(10);
+  if( p==0 ) return SQLITE_NOMEM_BKPT;
+  sqlite3_free(p);
+  return sqlite3_os_init();
+}
+
+/*
+** The list of all registered VFS implementations.
+*/
+static sqlite3_vfs * SQLITE_WSD vfsList = 0;
+#define vfsList GLOBAL(sqlite3_vfs *, vfsList)
+
+/*
+** Locate a VFS by name.  If no name is given, simply return the
+** first VFS on the list.
+*/
+SQLITE_API sqlite3_vfs *sqlite3_vfs_find(const char *zVfs){
+  sqlite3_vfs *pVfs = 0;
+#if SQLITE_THREADSAFE
+  sqlite3_mutex *mutex;
+#endif
+#ifndef SQLITE_OMIT_AUTOINIT
+  int rc = sqlite3_initialize();
+  if( rc ) return 0;
+#endif
+#if SQLITE_THREADSAFE
+  mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
+#endif
+  sqlite3_mutex_enter(mutex);
+  for(pVfs = vfsList; pVfs; pVfs=pVfs->pNext){
+    if( zVfs==0 ) break;
+    if( strcmp(zVfs, pVfs->zName)==0 ) break;
+  }
+  sqlite3_mutex_leave(mutex);
+  return pVfs;
+}
+
+/*
+** Unlink a VFS from the linked list
+*/
+static void vfsUnlink(sqlite3_vfs *pVfs){
+  assert( sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER)) );
+  if( pVfs==0 ){
+    /* No-op */
+  }else if( vfsList==pVfs ){
+    vfsList = pVfs->pNext;
+  }else if( vfsList ){
+    sqlite3_vfs *p = vfsList;
+    while( p->pNext && p->pNext!=pVfs ){
+      p = p->pNext;
+    }
+    if( p->pNext==pVfs ){
+      p->pNext = pVfs->pNext;
+    }
+  }
+}
+
+/*
+** Register a VFS with the system.  It is harmless to register the same
+** VFS multiple times.  The new VFS becomes the default if makeDflt is
+** true.
+*/
+SQLITE_API int sqlite3_vfs_register(sqlite3_vfs *pVfs, int makeDflt){
+  MUTEX_LOGIC(sqlite3_mutex *mutex;)
+#ifndef SQLITE_OMIT_AUTOINIT
+  int rc = sqlite3_initialize();
+  if( rc ) return rc;
+#endif
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( pVfs==0 ) return SQLITE_MISUSE_BKPT;
+#endif
+
+  MUTEX_LOGIC( mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); )
+  sqlite3_mutex_enter(mutex);
+  vfsUnlink(pVfs);
+  if( makeDflt || vfsList==0 ){
+    pVfs->pNext = vfsList;
+    vfsList = pVfs;
+  }else{
+    pVfs->pNext = vfsList->pNext;
+    vfsList->pNext = pVfs;
+  }
+  assert(vfsList);
+  sqlite3_mutex_leave(mutex);
+  return SQLITE_OK;
+}
+
+/*
+** Unregister a VFS so that it is no longer accessible.
+*/
+SQLITE_API int sqlite3_vfs_unregister(sqlite3_vfs *pVfs){
+#if SQLITE_THREADSAFE
+  sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
+#endif
+  sqlite3_mutex_enter(mutex);
+  vfsUnlink(pVfs);
+  sqlite3_mutex_leave(mutex);
+  return SQLITE_OK;
+}
+
+/************** End of os.c **************************************************/
+/************** Begin file fault.c *******************************************/
+/*
+** 2008 Jan 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains code to support the concept of "benign" 
+** malloc failures (when the xMalloc() or xRealloc() method of the
+** sqlite3_mem_methods structure fails to allocate a block of memory
+** and returns 0). 
+**
+** Most malloc failures are non-benign. After they occur, SQLite
+** abandons the current operation and returns an error code (usually
+** SQLITE_NOMEM) to the user. However, sometimes a fault is not necessarily
+** fatal. For example, if a malloc fails while resizing a hash table, this 
+** is completely recoverable simply by not carrying out the resize. The 
+** hash table will continue to function normally.  So a malloc failure 
+** during a hash table resize is a benign fault.
+*/
+
+/* #include "sqliteInt.h" */
+
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+
+/*
+** Global variables.
+*/
+typedef struct BenignMallocHooks BenignMallocHooks;
+static SQLITE_WSD struct BenignMallocHooks {
+  void (*xBenignBegin)(void);
+  void (*xBenignEnd)(void);
+} sqlite3Hooks = { 0, 0 };
+
+/* The "wsdHooks" macro will resolve to the appropriate BenignMallocHooks
+** structure.  If writable static data is unsupported on the target,
+** we have to locate the state vector at run-time.  In the more common
+** case where writable static data is supported, wsdHooks can refer directly
+** to the "sqlite3Hooks" state vector declared above.
+*/
+#ifdef SQLITE_OMIT_WSD
+# define wsdHooksInit \
+  BenignMallocHooks *x = &GLOBAL(BenignMallocHooks,sqlite3Hooks)
+# define wsdHooks x[0]
+#else
+# define wsdHooksInit
+# define wsdHooks sqlite3Hooks
+#endif
+
+
+/*
+** Register hooks to call when sqlite3BeginBenignMalloc() and
+** sqlite3EndBenignMalloc() are called, respectively.
+*/
+SQLITE_PRIVATE void sqlite3BenignMallocHooks(
+  void (*xBenignBegin)(void),
+  void (*xBenignEnd)(void)
+){
+  wsdHooksInit;
+  wsdHooks.xBenignBegin = xBenignBegin;
+  wsdHooks.xBenignEnd = xBenignEnd;
+}
+
+/*
+** This (sqlite3EndBenignMalloc()) is called by SQLite code to indicate that
+** subsequent malloc failures are benign. A call to sqlite3EndBenignMalloc()
+** indicates that subsequent malloc failures are non-benign.
+*/
+SQLITE_PRIVATE void sqlite3BeginBenignMalloc(void){
+  wsdHooksInit;
+  if( wsdHooks.xBenignBegin ){
+    wsdHooks.xBenignBegin();
+  }
+}
+SQLITE_PRIVATE void sqlite3EndBenignMalloc(void){
+  wsdHooksInit;
+  if( wsdHooks.xBenignEnd ){
+    wsdHooks.xBenignEnd();
+  }
+}
+
+#endif   /* #ifndef SQLITE_OMIT_BUILTIN_TEST */
+
+/************** End of fault.c ***********************************************/
+/************** Begin file mem0.c ********************************************/
+/*
+** 2008 October 28
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains a no-op memory allocation drivers for use when
+** SQLITE_ZERO_MALLOC is defined.  The allocation drivers implemented
+** here always fail.  SQLite will not operate with these drivers.  These
+** are merely placeholders.  Real drivers must be substituted using
+** sqlite3_config() before SQLite will operate.
+*/
+/* #include "sqliteInt.h" */
+
+/*
+** This version of the memory allocator is the default.  It is
+** used when no other memory allocator is specified using compile-time
+** macros.
+*/
+#ifdef SQLITE_ZERO_MALLOC
+
+/*
+** No-op versions of all memory allocation routines
+*/
+static void *sqlite3MemMalloc(int nByte){ return 0; }
+static void sqlite3MemFree(void *pPrior){ return; }
+static void *sqlite3MemRealloc(void *pPrior, int nByte){ return 0; }
+static int sqlite3MemSize(void *pPrior){ return 0; }
+static int sqlite3MemRoundup(int n){ return n; }
+static int sqlite3MemInit(void *NotUsed){ return SQLITE_OK; }
+static void sqlite3MemShutdown(void *NotUsed){ return; }
+
+/*
+** This routine is the only routine in this file with external linkage.
+**
+** Populate the low-level memory allocation function pointers in
+** sqlite3GlobalConfig.m with pointers to the routines in this file.
+*/
+SQLITE_PRIVATE void sqlite3MemSetDefault(void){
+  static const sqlite3_mem_methods defaultMethods = {
+     sqlite3MemMalloc,
+     sqlite3MemFree,
+     sqlite3MemRealloc,
+     sqlite3MemSize,
+     sqlite3MemRoundup,
+     sqlite3MemInit,
+     sqlite3MemShutdown,
+     0
+  };
+  sqlite3_config(SQLITE_CONFIG_MALLOC, &defaultMethods);
+}
+
+#endif /* SQLITE_ZERO_MALLOC */
+
+/************** End of mem0.c ************************************************/
+/************** Begin file mem1.c ********************************************/
+/*
+** 2007 August 14
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains low-level memory allocation drivers for when
+** SQLite will use the standard C-library malloc/realloc/free interface
+** to obtain the memory it needs.
+**
+** This file contains implementations of the low-level memory allocation
+** routines specified in the sqlite3_mem_methods object.  The content of
+** this file is only used if SQLITE_SYSTEM_MALLOC is defined.  The
+** SQLITE_SYSTEM_MALLOC macro is defined automatically if neither the
+** SQLITE_MEMDEBUG nor the SQLITE_WIN32_MALLOC macros are defined.  The
+** default configuration is to use memory allocation routines in this
+** file.
+**
+** C-preprocessor macro summary:
+**
+**    HAVE_MALLOC_USABLE_SIZE     The configure script sets this symbol if
+**                                the malloc_usable_size() interface exists
+**                                on the target platform.  Or, this symbol
+**                                can be set manually, if desired.
+**                                If an equivalent interface exists by
+**                                a different name, using a separate -D
+**                                option to rename it.
+**
+**    SQLITE_WITHOUT_ZONEMALLOC   Some older macs lack support for the zone
+**                                memory allocator.  Set this symbol to enable
+**                                building on older macs.
+**
+**    SQLITE_WITHOUT_MSIZE        Set this symbol to disable the use of
+**                                _msize() on windows systems.  This might
+**                                be necessary when compiling for Delphi,
+**                                for example.
+*/
+/* #include "sqliteInt.h" */
+
+/*
+** This version of the memory allocator is the default.  It is
+** used when no other memory allocator is specified using compile-time
+** macros.
+*/
+#ifdef SQLITE_SYSTEM_MALLOC
+#if defined(__APPLE__) && !defined(SQLITE_WITHOUT_ZONEMALLOC)
+
+/*
+** Use the zone allocator available on apple products unless the
+** SQLITE_WITHOUT_ZONEMALLOC symbol is defined.
+*/
+#include <sys/sysctl.h>
+#include <malloc/malloc.h>
+#include <libkern/OSAtomic.h>
+static malloc_zone_t* _sqliteZone_;
+#define SQLITE_MALLOC(x) malloc_zone_malloc(_sqliteZone_, (x))
+#define SQLITE_FREE(x) malloc_zone_free(_sqliteZone_, (x));
+#define SQLITE_REALLOC(x,y) malloc_zone_realloc(_sqliteZone_, (x), (y))
+#define SQLITE_MALLOCSIZE(x) \
+        (_sqliteZone_ ? _sqliteZone_->size(_sqliteZone_,x) : malloc_size(x))
+
+#else /* if not __APPLE__ */
+
+/*
+** Use standard C library malloc and free on non-Apple systems.  
+** Also used by Apple systems if SQLITE_WITHOUT_ZONEMALLOC is defined.
+*/
+#define SQLITE_MALLOC(x)             malloc(x)
+#define SQLITE_FREE(x)               free(x)
+#define SQLITE_REALLOC(x,y)          realloc((x),(y))
+
+/*
+** The malloc.h header file is needed for malloc_usable_size() function
+** on some systems (e.g. Linux).
+*/
+#if HAVE_MALLOC_H && HAVE_MALLOC_USABLE_SIZE
+#  define SQLITE_USE_MALLOC_H 1
+#  define SQLITE_USE_MALLOC_USABLE_SIZE 1
+/*
+** The MSVCRT has malloc_usable_size(), but it is called _msize().  The
+** use of _msize() is automatic, but can be disabled by compiling with
+** -DSQLITE_WITHOUT_MSIZE.  Using the _msize() function also requires
+** the malloc.h header file.
+*/
+#elif defined(_MSC_VER) && !defined(SQLITE_WITHOUT_MSIZE)
+#  define SQLITE_USE_MALLOC_H
+#  define SQLITE_USE_MSIZE
+#endif
+
+/*
+** Include the malloc.h header file, if necessary.  Also set define macro
+** SQLITE_MALLOCSIZE to the appropriate function name, which is _msize()
+** for MSVC and malloc_usable_size() for most other systems (e.g. Linux).
+** The memory size function can always be overridden manually by defining
+** the macro SQLITE_MALLOCSIZE to the desired function name.
+*/
+#if defined(SQLITE_USE_MALLOC_H)
+#  include <malloc.h>
+#  if defined(SQLITE_USE_MALLOC_USABLE_SIZE)
+#    if !defined(SQLITE_MALLOCSIZE)
+#      define SQLITE_MALLOCSIZE(x)   malloc_usable_size(x)
+#    endif
+#  elif defined(SQLITE_USE_MSIZE)
+#    if !defined(SQLITE_MALLOCSIZE)
+#      define SQLITE_MALLOCSIZE      _msize
+#    endif
+#  endif
+#endif /* defined(SQLITE_USE_MALLOC_H) */
+
+#endif /* __APPLE__ or not __APPLE__ */
+
+/*
+** Like malloc(), but remember the size of the allocation
+** so that we can find it later using sqlite3MemSize().
+**
+** For this low-level routine, we are guaranteed that nByte>0 because
+** cases of nByte<=0 will be intercepted and dealt with by higher level
+** routines.
+*/
+static void *sqlite3MemMalloc(int nByte){
+#ifdef SQLITE_MALLOCSIZE
+  void *p = SQLITE_MALLOC( nByte );
+  if( p==0 ){
+    testcase( sqlite3GlobalConfig.xLog!=0 );
+    sqlite3_log(SQLITE_NOMEM, "failed to allocate %u bytes of memory", nByte);
+  }
+  return p;
+#else
+  sqlite3_int64 *p;
+  assert( nByte>0 );
+  nByte = ROUND8(nByte);
+  p = SQLITE_MALLOC( nByte+8 );
+  if( p ){
+    p[0] = nByte;
+    p++;
+  }else{
+    testcase( sqlite3GlobalConfig.xLog!=0 );
+    sqlite3_log(SQLITE_NOMEM, "failed to allocate %u bytes of memory", nByte);
+  }
+  return (void *)p;
+#endif
+}
+
+/*
+** Like free() but works for allocations obtained from sqlite3MemMalloc()
+** or sqlite3MemRealloc().
+**
+** For this low-level routine, we already know that pPrior!=0 since
+** cases where pPrior==0 will have been intecepted and dealt with
+** by higher-level routines.
+*/
+static void sqlite3MemFree(void *pPrior){
+#ifdef SQLITE_MALLOCSIZE
+  SQLITE_FREE(pPrior);
+#else
+  sqlite3_int64 *p = (sqlite3_int64*)pPrior;
+  assert( pPrior!=0 );
+  p--;
+  SQLITE_FREE(p);
+#endif
+}
+
+/*
+** Report the allocated size of a prior return from xMalloc()
+** or xRealloc().
+*/
+static int sqlite3MemSize(void *pPrior){
+#ifdef SQLITE_MALLOCSIZE
+  assert( pPrior!=0 );
+  return (int)SQLITE_MALLOCSIZE(pPrior);
+#else
+  sqlite3_int64 *p;
+  assert( pPrior!=0 );
+  p = (sqlite3_int64*)pPrior;
+  p--;
+  return (int)p[0];
+#endif
+}
+
+/*
+** Like realloc().  Resize an allocation previously obtained from
+** sqlite3MemMalloc().
+**
+** For this low-level interface, we know that pPrior!=0.  Cases where
+** pPrior==0 while have been intercepted by higher-level routine and
+** redirected to xMalloc.  Similarly, we know that nByte>0 because
+** cases where nByte<=0 will have been intercepted by higher-level
+** routines and redirected to xFree.
+*/
+static void *sqlite3MemRealloc(void *pPrior, int nByte){
+#ifdef SQLITE_MALLOCSIZE
+  void *p = SQLITE_REALLOC(pPrior, nByte);
+  if( p==0 ){
+    testcase( sqlite3GlobalConfig.xLog!=0 );
+    sqlite3_log(SQLITE_NOMEM,
+      "failed memory resize %u to %u bytes",
+      SQLITE_MALLOCSIZE(pPrior), nByte);
+  }
+  return p;
+#else
+  sqlite3_int64 *p = (sqlite3_int64*)pPrior;
+  assert( pPrior!=0 && nByte>0 );
+  assert( nByte==ROUND8(nByte) ); /* EV: R-46199-30249 */
+  p--;
+  p = SQLITE_REALLOC(p, nByte+8 );
+  if( p ){
+    p[0] = nByte;
+    p++;
+  }else{
+    testcase( sqlite3GlobalConfig.xLog!=0 );
+    sqlite3_log(SQLITE_NOMEM,
+      "failed memory resize %u to %u bytes",
+      sqlite3MemSize(pPrior), nByte);
+  }
+  return (void*)p;
+#endif
+}
+
+/*
+** Round up a request size to the next valid allocation size.
+*/
+static int sqlite3MemRoundup(int n){
+  return ROUND8(n);
+}
+
+/*
+** Initialize this module.
+*/
+static int sqlite3MemInit(void *NotUsed){
+#if defined(__APPLE__) && !defined(SQLITE_WITHOUT_ZONEMALLOC)
+  int cpuCount;
+  size_t len;
+  if( _sqliteZone_ ){
+    return SQLITE_OK;
+  }
+  len = sizeof(cpuCount);
+  /* One usually wants to use hw.acctivecpu for MT decisions, but not here */
+  sysctlbyname("hw.ncpu", &cpuCount, &len, NULL, 0);
+  if( cpuCount>1 ){
+    /* defer MT decisions to system malloc */
+    _sqliteZone_ = malloc_default_zone();
+  }else{
+    /* only 1 core, use our own zone to contention over global locks, 
+    ** e.g. we have our own dedicated locks */
+    bool success;
+    malloc_zone_t* newzone = malloc_create_zone(4096, 0);
+    malloc_set_zone_name(newzone, "Sqlite_Heap");
+    do{
+      success = OSAtomicCompareAndSwapPtrBarrier(NULL, newzone, 
+                                 (void * volatile *)&_sqliteZone_);
+    }while(!_sqliteZone_);
+    if( !success ){
+      /* somebody registered a zone first */
+      malloc_destroy_zone(newzone);
+    }
+  }
+#endif
+  UNUSED_PARAMETER(NotUsed);
+  return SQLITE_OK;
+}
+
+/*
+** Deinitialize this module.
+*/
+static void sqlite3MemShutdown(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  return;
+}
+
+/*
+** This routine is the only routine in this file with external linkage.
+**
+** Populate the low-level memory allocation function pointers in
+** sqlite3GlobalConfig.m with pointers to the routines in this file.
+*/
+SQLITE_PRIVATE void sqlite3MemSetDefault(void){
+  static const sqlite3_mem_methods defaultMethods = {
+     sqlite3MemMalloc,
+     sqlite3MemFree,
+     sqlite3MemRealloc,
+     sqlite3MemSize,
+     sqlite3MemRoundup,
+     sqlite3MemInit,
+     sqlite3MemShutdown,
+     0
+  };
+  sqlite3_config(SQLITE_CONFIG_MALLOC, &defaultMethods);
+}
+
+#endif /* SQLITE_SYSTEM_MALLOC */
+
+/************** End of mem1.c ************************************************/
+/************** Begin file mem2.c ********************************************/
+/*
+** 2007 August 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains low-level memory allocation drivers for when
+** SQLite will use the standard C-library malloc/realloc/free interface
+** to obtain the memory it needs while adding lots of additional debugging
+** information to each allocation in order to help detect and fix memory
+** leaks and memory usage errors.
+**
+** This file contains implementations of the low-level memory allocation
+** routines specified in the sqlite3_mem_methods object.
+*/
+/* #include "sqliteInt.h" */
+
+/*
+** This version of the memory allocator is used only if the
+** SQLITE_MEMDEBUG macro is defined
+*/
+#ifdef SQLITE_MEMDEBUG
+
+/*
+** The backtrace functionality is only available with GLIBC
+*/
+#ifdef __GLIBC__
+  extern int backtrace(void**,int);
+  extern void backtrace_symbols_fd(void*const*,int,int);
+#else
+# define backtrace(A,B) 1
+# define backtrace_symbols_fd(A,B,C)
+#endif
+/* #include <stdio.h> */
+
+/*
+** Each memory allocation looks like this:
+**
+**  ------------------------------------------------------------------------
+**  | Title |  backtrace pointers |  MemBlockHdr |  allocation |  EndGuard |
+**  ------------------------------------------------------------------------
+**
+** The application code sees only a pointer to the allocation.  We have
+** to back up from the allocation pointer to find the MemBlockHdr.  The
+** MemBlockHdr tells us the size of the allocation and the number of
+** backtrace pointers.  There is also a guard word at the end of the
+** MemBlockHdr.
+*/
+struct MemBlockHdr {
+  i64 iSize;                          /* Size of this allocation */
+  struct MemBlockHdr *pNext, *pPrev;  /* Linked list of all unfreed memory */
+  char nBacktrace;                    /* Number of backtraces on this alloc */
+  char nBacktraceSlots;               /* Available backtrace slots */
+  u8 nTitle;                          /* Bytes of title; includes '\0' */
+  u8 eType;                           /* Allocation type code */
+  int iForeGuard;                     /* Guard word for sanity */
+};
+
+/*
+** Guard words
+*/
+#define FOREGUARD 0x80F5E153
+#define REARGUARD 0xE4676B53
+
+/*
+** Number of malloc size increments to track.
+*/
+#define NCSIZE  1000
+
+/*
+** All of the static variables used by this module are collected
+** into a single structure named "mem".  This is to keep the
+** static variables organized and to reduce namespace pollution
+** when this module is combined with other in the amalgamation.
+*/
+static struct {
+  
+  /*
+  ** Mutex to control access to the memory allocation subsystem.
+  */
+  sqlite3_mutex *mutex;
+
+  /*
+  ** Head and tail of a linked list of all outstanding allocations
+  */
+  struct MemBlockHdr *pFirst;
+  struct MemBlockHdr *pLast;
+  
+  /*
+  ** The number of levels of backtrace to save in new allocations.
+  */
+  int nBacktrace;
+  void (*xBacktrace)(int, int, void **);
+
+  /*
+  ** Title text to insert in front of each block
+  */
+  int nTitle;        /* Bytes of zTitle to save.  Includes '\0' and padding */
+  char zTitle[100];  /* The title text */
+
+  /* 
+  ** sqlite3MallocDisallow() increments the following counter.
+  ** sqlite3MallocAllow() decrements it.
+  */
+  int disallow; /* Do not allow memory allocation */
+
+  /*
+  ** Gather statistics on the sizes of memory allocations.
+  ** nAlloc[i] is the number of allocation attempts of i*8
+  ** bytes.  i==NCSIZE is the number of allocation attempts for
+  ** sizes more than NCSIZE*8 bytes.
+  */
+  int nAlloc[NCSIZE];      /* Total number of allocations */
+  int nCurrent[NCSIZE];    /* Current number of allocations */
+  int mxCurrent[NCSIZE];   /* Highwater mark for nCurrent */
+
+} mem;
+
+
+/*
+** Adjust memory usage statistics
+*/
+static void adjustStats(int iSize, int increment){
+  int i = ROUND8(iSize)/8;
+  if( i>NCSIZE-1 ){
+    i = NCSIZE - 1;
+  }
+  if( increment>0 ){
+    mem.nAlloc[i]++;
+    mem.nCurrent[i]++;
+    if( mem.nCurrent[i]>mem.mxCurrent[i] ){
+      mem.mxCurrent[i] = mem.nCurrent[i];
+    }
+  }else{
+    mem.nCurrent[i]--;
+    assert( mem.nCurrent[i]>=0 );
+  }
+}
+
+/*
+** Given an allocation, find the MemBlockHdr for that allocation.
+**
+** This routine checks the guards at either end of the allocation and
+** if they are incorrect it asserts.
+*/
+static struct MemBlockHdr *sqlite3MemsysGetHeader(void *pAllocation){
+  struct MemBlockHdr *p;
+  int *pInt;
+  u8 *pU8;
+  int nReserve;
+
+  p = (struct MemBlockHdr*)pAllocation;
+  p--;
+  assert( p->iForeGuard==(int)FOREGUARD );
+  nReserve = ROUND8(p->iSize);
+  pInt = (int*)pAllocation;
+  pU8 = (u8*)pAllocation;
+  assert( pInt[nReserve/sizeof(int)]==(int)REARGUARD );
+  /* This checks any of the "extra" bytes allocated due
+  ** to rounding up to an 8 byte boundary to ensure 
+  ** they haven't been overwritten.
+  */
+  while( nReserve-- > p->iSize ) assert( pU8[nReserve]==0x65 );
+  return p;
+}
+
+/*
+** Return the number of bytes currently allocated at address p.
+*/
+static int sqlite3MemSize(void *p){
+  struct MemBlockHdr *pHdr;
+  if( !p ){
+    return 0;
+  }
+  pHdr = sqlite3MemsysGetHeader(p);
+  return (int)pHdr->iSize;
+}
+
+/*
+** Initialize the memory allocation subsystem.
+*/
+static int sqlite3MemInit(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  assert( (sizeof(struct MemBlockHdr)&7) == 0 );
+  if( !sqlite3GlobalConfig.bMemstat ){
+    /* If memory status is enabled, then the malloc.c wrapper will already
+    ** hold the STATIC_MEM mutex when the routines here are invoked. */
+    mem.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Deinitialize the memory allocation subsystem.
+*/
+static void sqlite3MemShutdown(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  mem.mutex = 0;
+}
+
+/*
+** Round up a request size to the next valid allocation size.
+*/
+static int sqlite3MemRoundup(int n){
+  return ROUND8(n);
+}
+
+/*
+** Fill a buffer with pseudo-random bytes.  This is used to preset
+** the content of a new memory allocation to unpredictable values and
+** to clear the content of a freed allocation to unpredictable values.
+*/
+static void randomFill(char *pBuf, int nByte){
+  unsigned int x, y, r;
+  x = SQLITE_PTR_TO_INT(pBuf);
+  y = nByte | 1;
+  while( nByte >= 4 ){
+    x = (x>>1) ^ (-(int)(x&1) & 0xd0000001);
+    y = y*1103515245 + 12345;
+    r = x ^ y;
+    *(int*)pBuf = r;
+    pBuf += 4;
+    nByte -= 4;
+  }
+  while( nByte-- > 0 ){
+    x = (x>>1) ^ (-(int)(x&1) & 0xd0000001);
+    y = y*1103515245 + 12345;
+    r = x ^ y;
+    *(pBuf++) = r & 0xff;
+  }
+}
+
+/*
+** Allocate nByte bytes of memory.
+*/
+static void *sqlite3MemMalloc(int nByte){
+  struct MemBlockHdr *pHdr;
+  void **pBt;
+  char *z;
+  int *pInt;
+  void *p = 0;
+  int totalSize;
+  int nReserve;
+  sqlite3_mutex_enter(mem.mutex);
+  assert( mem.disallow==0 );
+  nReserve = ROUND8(nByte);
+  totalSize = nReserve + sizeof(*pHdr) + sizeof(int) +
+               mem.nBacktrace*sizeof(void*) + mem.nTitle;
+  p = malloc(totalSize);
+  if( p ){
+    z = p;
+    pBt = (void**)&z[mem.nTitle];
+    pHdr = (struct MemBlockHdr*)&pBt[mem.nBacktrace];
+    pHdr->pNext = 0;
+    pHdr->pPrev = mem.pLast;
+    if( mem.pLast ){
+      mem.pLast->pNext = pHdr;
+    }else{
+      mem.pFirst = pHdr;
+    }
+    mem.pLast = pHdr;
+    pHdr->iForeGuard = FOREGUARD;
+    pHdr->eType = MEMTYPE_HEAP;
+    pHdr->nBacktraceSlots = mem.nBacktrace;
+    pHdr->nTitle = mem.nTitle;
+    if( mem.nBacktrace ){
+      void *aAddr[40];
+      pHdr->nBacktrace = backtrace(aAddr, mem.nBacktrace+1)-1;
+      memcpy(pBt, &aAddr[1], pHdr->nBacktrace*sizeof(void*));
+      assert(pBt[0]);
+      if( mem.xBacktrace ){
+        mem.xBacktrace(nByte, pHdr->nBacktrace-1, &aAddr[1]);
+      }
+    }else{
+      pHdr->nBacktrace = 0;
+    }
+    if( mem.nTitle ){
+      memcpy(z, mem.zTitle, mem.nTitle);
+    }
+    pHdr->iSize = nByte;
+    adjustStats(nByte, +1);
+    pInt = (int*)&pHdr[1];
+    pInt[nReserve/sizeof(int)] = REARGUARD;
+    randomFill((char*)pInt, nByte);
+    memset(((char*)pInt)+nByte, 0x65, nReserve-nByte);
+    p = (void*)pInt;
+  }
+  sqlite3_mutex_leave(mem.mutex);
+  return p; 
+}
+
+/*
+** Free memory.
+*/
+static void sqlite3MemFree(void *pPrior){
+  struct MemBlockHdr *pHdr;
+  void **pBt;
+  char *z;
+  assert( sqlite3GlobalConfig.bMemstat || sqlite3GlobalConfig.bCoreMutex==0 
+       || mem.mutex!=0 );
+  pHdr = sqlite3MemsysGetHeader(pPrior);
+  pBt = (void**)pHdr;
+  pBt -= pHdr->nBacktraceSlots;
+  sqlite3_mutex_enter(mem.mutex);
+  if( pHdr->pPrev ){
+    assert( pHdr->pPrev->pNext==pHdr );
+    pHdr->pPrev->pNext = pHdr->pNext;
+  }else{
+    assert( mem.pFirst==pHdr );
+    mem.pFirst = pHdr->pNext;
+  }
+  if( pHdr->pNext ){
+    assert( pHdr->pNext->pPrev==pHdr );
+    pHdr->pNext->pPrev = pHdr->pPrev;
+  }else{
+    assert( mem.pLast==pHdr );
+    mem.pLast = pHdr->pPrev;
+  }
+  z = (char*)pBt;
+  z -= pHdr->nTitle;
+  adjustStats((int)pHdr->iSize, -1);
+  randomFill(z, sizeof(void*)*pHdr->nBacktraceSlots + sizeof(*pHdr) +
+                (int)pHdr->iSize + sizeof(int) + pHdr->nTitle);
+  free(z);
+  sqlite3_mutex_leave(mem.mutex);  
+}
+
+/*
+** Change the size of an existing memory allocation.
+**
+** For this debugging implementation, we *always* make a copy of the
+** allocation into a new place in memory.  In this way, if the 
+** higher level code is using pointer to the old allocation, it is 
+** much more likely to break and we are much more liking to find
+** the error.
+*/
+static void *sqlite3MemRealloc(void *pPrior, int nByte){
+  struct MemBlockHdr *pOldHdr;
+  void *pNew;
+  assert( mem.disallow==0 );
+  assert( (nByte & 7)==0 );     /* EV: R-46199-30249 */
+  pOldHdr = sqlite3MemsysGetHeader(pPrior);
+  pNew = sqlite3MemMalloc(nByte);
+  if( pNew ){
+    memcpy(pNew, pPrior, (int)(nByte<pOldHdr->iSize ? nByte : pOldHdr->iSize));
+    if( nByte>pOldHdr->iSize ){
+      randomFill(&((char*)pNew)[pOldHdr->iSize], nByte - (int)pOldHdr->iSize);
+    }
+    sqlite3MemFree(pPrior);
+  }
+  return pNew;
+}
+
+/*
+** Populate the low-level memory allocation function pointers in
+** sqlite3GlobalConfig.m with pointers to the routines in this file.
+*/
+SQLITE_PRIVATE void sqlite3MemSetDefault(void){
+  static const sqlite3_mem_methods defaultMethods = {
+     sqlite3MemMalloc,
+     sqlite3MemFree,
+     sqlite3MemRealloc,
+     sqlite3MemSize,
+     sqlite3MemRoundup,
+     sqlite3MemInit,
+     sqlite3MemShutdown,
+     0
+  };
+  sqlite3_config(SQLITE_CONFIG_MALLOC, &defaultMethods);
+}
+
+/*
+** Set the "type" of an allocation.
+*/
+SQLITE_PRIVATE void sqlite3MemdebugSetType(void *p, u8 eType){
+  if( p && sqlite3GlobalConfig.m.xMalloc==sqlite3MemMalloc ){
+    struct MemBlockHdr *pHdr;
+    pHdr = sqlite3MemsysGetHeader(p);
+    assert( pHdr->iForeGuard==FOREGUARD );
+    pHdr->eType = eType;
+  }
+}
+
+/*
+** Return TRUE if the mask of type in eType matches the type of the
+** allocation p.  Also return true if p==NULL.
+**
+** This routine is designed for use within an assert() statement, to
+** verify the type of an allocation.  For example:
+**
+**     assert( sqlite3MemdebugHasType(p, MEMTYPE_HEAP) );
+*/
+SQLITE_PRIVATE int sqlite3MemdebugHasType(void *p, u8 eType){
+  int rc = 1;
+  if( p && sqlite3GlobalConfig.m.xMalloc==sqlite3MemMalloc ){
+    struct MemBlockHdr *pHdr;
+    pHdr = sqlite3MemsysGetHeader(p);
+    assert( pHdr->iForeGuard==FOREGUARD );         /* Allocation is valid */
+    if( (pHdr->eType&eType)==0 ){
+      rc = 0;
+    }
+  }
+  return rc;
+}
+
+/*
+** Return TRUE if the mask of type in eType matches no bits of the type of the
+** allocation p.  Also return true if p==NULL.
+**
+** This routine is designed for use within an assert() statement, to
+** verify the type of an allocation.  For example:
+**
+**     assert( sqlite3MemdebugNoType(p, MEMTYPE_LOOKASIDE) );
+*/
+SQLITE_PRIVATE int sqlite3MemdebugNoType(void *p, u8 eType){
+  int rc = 1;
+  if( p && sqlite3GlobalConfig.m.xMalloc==sqlite3MemMalloc ){
+    struct MemBlockHdr *pHdr;
+    pHdr = sqlite3MemsysGetHeader(p);
+    assert( pHdr->iForeGuard==FOREGUARD );         /* Allocation is valid */
+    if( (pHdr->eType&eType)!=0 ){
+      rc = 0;
+    }
+  }
+  return rc;
+}
+
+/*
+** Set the number of backtrace levels kept for each allocation.
+** A value of zero turns off backtracing.  The number is always rounded
+** up to a multiple of 2.
+*/
+SQLITE_PRIVATE void sqlite3MemdebugBacktrace(int depth){
+  if( depth<0 ){ depth = 0; }
+  if( depth>20 ){ depth = 20; }
+  depth = (depth+1)&0xfe;
+  mem.nBacktrace = depth;
+}
+
+SQLITE_PRIVATE void sqlite3MemdebugBacktraceCallback(void (*xBacktrace)(int, int, void **)){
+  mem.xBacktrace = xBacktrace;
+}
+
+/*
+** Set the title string for subsequent allocations.
+*/
+SQLITE_PRIVATE void sqlite3MemdebugSettitle(const char *zTitle){
+  unsigned int n = sqlite3Strlen30(zTitle) + 1;
+  sqlite3_mutex_enter(mem.mutex);
+  if( n>=sizeof(mem.zTitle) ) n = sizeof(mem.zTitle)-1;
+  memcpy(mem.zTitle, zTitle, n);
+  mem.zTitle[n] = 0;
+  mem.nTitle = ROUND8(n);
+  sqlite3_mutex_leave(mem.mutex);
+}
+
+SQLITE_PRIVATE void sqlite3MemdebugSync(){
+  struct MemBlockHdr *pHdr;
+  for(pHdr=mem.pFirst; pHdr; pHdr=pHdr->pNext){
+    void **pBt = (void**)pHdr;
+    pBt -= pHdr->nBacktraceSlots;
+    mem.xBacktrace((int)pHdr->iSize, pHdr->nBacktrace-1, &pBt[1]);
+  }
+}
+
+/*
+** Open the file indicated and write a log of all unfreed memory 
+** allocations into that log.
+*/
+SQLITE_PRIVATE void sqlite3MemdebugDump(const char *zFilename){
+  FILE *out;
+  struct MemBlockHdr *pHdr;
+  void **pBt;
+  int i;
+  out = fopen(zFilename, "w");
+  if( out==0 ){
+    fprintf(stderr, "** Unable to output memory debug output log: %s **\n",
+                    zFilename);
+    return;
+  }
+  for(pHdr=mem.pFirst; pHdr; pHdr=pHdr->pNext){
+    char *z = (char*)pHdr;
+    z -= pHdr->nBacktraceSlots*sizeof(void*) + pHdr->nTitle;
+    fprintf(out, "**** %lld bytes at %p from %s ****\n", 
+            pHdr->iSize, &pHdr[1], pHdr->nTitle ? z : "???");
+    if( pHdr->nBacktrace ){
+      fflush(out);
+      pBt = (void**)pHdr;
+      pBt -= pHdr->nBacktraceSlots;
+      backtrace_symbols_fd(pBt, pHdr->nBacktrace, fileno(out));
+      fprintf(out, "\n");
+    }
+  }
+  fprintf(out, "COUNTS:\n");
+  for(i=0; i<NCSIZE-1; i++){
+    if( mem.nAlloc[i] ){
+      fprintf(out, "   %5d: %10d %10d %10d\n", 
+            i*8, mem.nAlloc[i], mem.nCurrent[i], mem.mxCurrent[i]);
+    }
+  }
+  if( mem.nAlloc[NCSIZE-1] ){
+    fprintf(out, "   %5d: %10d %10d %10d\n",
+             NCSIZE*8-8, mem.nAlloc[NCSIZE-1],
+             mem.nCurrent[NCSIZE-1], mem.mxCurrent[NCSIZE-1]);
+  }
+  fclose(out);
+}
+
+/*
+** Return the number of times sqlite3MemMalloc() has been called.
+*/
+SQLITE_PRIVATE int sqlite3MemdebugMallocCount(){
+  int i;
+  int nTotal = 0;
+  for(i=0; i<NCSIZE; i++){
+    nTotal += mem.nAlloc[i];
+  }
+  return nTotal;
+}
+
+
+#endif /* SQLITE_MEMDEBUG */
+
+/************** End of mem2.c ************************************************/
+/************** Begin file mem3.c ********************************************/
+/*
+** 2007 October 14
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C functions that implement a memory
+** allocation subsystem for use by SQLite. 
+**
+** This version of the memory allocation subsystem omits all
+** use of malloc(). The SQLite user supplies a block of memory
+** before calling sqlite3_initialize() from which allocations
+** are made and returned by the xMalloc() and xRealloc() 
+** implementations. Once sqlite3_initialize() has been called,
+** the amount of memory available to SQLite is fixed and cannot
+** be changed.
+**
+** This version of the memory allocation subsystem is included
+** in the build only if SQLITE_ENABLE_MEMSYS3 is defined.
+*/
+/* #include "sqliteInt.h" */
+
+/*
+** This version of the memory allocator is only built into the library
+** SQLITE_ENABLE_MEMSYS3 is defined. Defining this symbol does not
+** mean that the library will use a memory-pool by default, just that
+** it is available. The mempool allocator is activated by calling
+** sqlite3_config().
+*/
+#ifdef SQLITE_ENABLE_MEMSYS3
+
+/*
+** Maximum size (in Mem3Blocks) of a "small" chunk.
+*/
+#define MX_SMALL 10
+
+
+/*
+** Number of freelist hash slots
+*/
+#define N_HASH  61
+
+/*
+** A memory allocation (also called a "chunk") consists of two or 
+** more blocks where each block is 8 bytes.  The first 8 bytes are 
+** a header that is not returned to the user.
+**
+** A chunk is two or more blocks that is either checked out or
+** free.  The first block has format u.hdr.  u.hdr.size4x is 4 times the
+** size of the allocation in blocks if the allocation is free.
+** The u.hdr.size4x&1 bit is true if the chunk is checked out and
+** false if the chunk is on the freelist.  The u.hdr.size4x&2 bit
+** is true if the previous chunk is checked out and false if the
+** previous chunk is free.  The u.hdr.prevSize field is the size of
+** the previous chunk in blocks if the previous chunk is on the
+** freelist. If the previous chunk is checked out, then
+** u.hdr.prevSize can be part of the data for that chunk and should
+** not be read or written.
+**
+** We often identify a chunk by its index in mem3.aPool[].  When
+** this is done, the chunk index refers to the second block of
+** the chunk.  In this way, the first chunk has an index of 1.
+** A chunk index of 0 means "no such chunk" and is the equivalent
+** of a NULL pointer.
+**
+** The second block of free chunks is of the form u.list.  The
+** two fields form a double-linked list of chunks of related sizes.
+** Pointers to the head of the list are stored in mem3.aiSmall[] 
+** for smaller chunks and mem3.aiHash[] for larger chunks.
+**
+** The second block of a chunk is user data if the chunk is checked 
+** out.  If a chunk is checked out, the user data may extend into
+** the u.hdr.prevSize value of the following chunk.
+*/
+typedef struct Mem3Block Mem3Block;
+struct Mem3Block {
+  union {
+    struct {
+      u32 prevSize;   /* Size of previous chunk in Mem3Block elements */
+      u32 size4x;     /* 4x the size of current chunk in Mem3Block elements */
+    } hdr;
+    struct {
+      u32 next;       /* Index in mem3.aPool[] of next free chunk */
+      u32 prev;       /* Index in mem3.aPool[] of previous free chunk */
+    } list;
+  } u;
+};
+
+/*
+** All of the static variables used by this module are collected
+** into a single structure named "mem3".  This is to keep the
+** static variables organized and to reduce namespace pollution
+** when this module is combined with other in the amalgamation.
+*/
+static SQLITE_WSD struct Mem3Global {
+  /*
+  ** Memory available for allocation. nPool is the size of the array
+  ** (in Mem3Blocks) pointed to by aPool less 2.
+  */
+  u32 nPool;
+  Mem3Block *aPool;
+
+  /*
+  ** True if we are evaluating an out-of-memory callback.
+  */
+  int alarmBusy;
+  
+  /*
+  ** Mutex to control access to the memory allocation subsystem.
+  */
+  sqlite3_mutex *mutex;
+  
+  /*
+  ** The minimum amount of free space that we have seen.
+  */
+  u32 mnMaster;
+
+  /*
+  ** iMaster is the index of the master chunk.  Most new allocations
+  ** occur off of this chunk.  szMaster is the size (in Mem3Blocks)
+  ** of the current master.  iMaster is 0 if there is not master chunk.
+  ** The master chunk is not in either the aiHash[] or aiSmall[].
+  */
+  u32 iMaster;
+  u32 szMaster;
+
+  /*
+  ** Array of lists of free blocks according to the block size 
+  ** for smaller chunks, or a hash on the block size for larger
+  ** chunks.
+  */
+  u32 aiSmall[MX_SMALL-1];   /* For sizes 2 through MX_SMALL, inclusive */
+  u32 aiHash[N_HASH];        /* For sizes MX_SMALL+1 and larger */
+} mem3 = { 97535575 };
+
+#define mem3 GLOBAL(struct Mem3Global, mem3)
+
+/*
+** Unlink the chunk at mem3.aPool[i] from list it is currently
+** on.  *pRoot is the list that i is a member of.
+*/
+static void memsys3UnlinkFromList(u32 i, u32 *pRoot){
+  u32 next = mem3.aPool[i].u.list.next;
+  u32 prev = mem3.aPool[i].u.list.prev;
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  if( prev==0 ){
+    *pRoot = next;
+  }else{
+    mem3.aPool[prev].u.list.next = next;
+  }
+  if( next ){
+    mem3.aPool[next].u.list.prev = prev;
+  }
+  mem3.aPool[i].u.list.next = 0;
+  mem3.aPool[i].u.list.prev = 0;
+}
+
+/*
+** Unlink the chunk at index i from 
+** whatever list is currently a member of.
+*/
+static void memsys3Unlink(u32 i){
+  u32 size, hash;
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  assert( (mem3.aPool[i-1].u.hdr.size4x & 1)==0 );
+  assert( i>=1 );
+  size = mem3.aPool[i-1].u.hdr.size4x/4;
+  assert( size==mem3.aPool[i+size-1].u.hdr.prevSize );
+  assert( size>=2 );
+  if( size <= MX_SMALL ){
+    memsys3UnlinkFromList(i, &mem3.aiSmall[size-2]);
+  }else{
+    hash = size % N_HASH;
+    memsys3UnlinkFromList(i, &mem3.aiHash[hash]);
+  }
+}
+
+/*
+** Link the chunk at mem3.aPool[i] so that is on the list rooted
+** at *pRoot.
+*/
+static void memsys3LinkIntoList(u32 i, u32 *pRoot){
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  mem3.aPool[i].u.list.next = *pRoot;
+  mem3.aPool[i].u.list.prev = 0;
+  if( *pRoot ){
+    mem3.aPool[*pRoot].u.list.prev = i;
+  }
+  *pRoot = i;
+}
+
+/*
+** Link the chunk at index i into either the appropriate
+** small chunk list, or into the large chunk hash table.
+*/
+static void memsys3Link(u32 i){
+  u32 size, hash;
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  assert( i>=1 );
+  assert( (mem3.aPool[i-1].u.hdr.size4x & 1)==0 );
+  size = mem3.aPool[i-1].u.hdr.size4x/4;
+  assert( size==mem3.aPool[i+size-1].u.hdr.prevSize );
+  assert( size>=2 );
+  if( size <= MX_SMALL ){
+    memsys3LinkIntoList(i, &mem3.aiSmall[size-2]);
+  }else{
+    hash = size % N_HASH;
+    memsys3LinkIntoList(i, &mem3.aiHash[hash]);
+  }
+}
+
+/*
+** If the STATIC_MEM mutex is not already held, obtain it now. The mutex
+** will already be held (obtained by code in malloc.c) if
+** sqlite3GlobalConfig.bMemStat is true.
+*/
+static void memsys3Enter(void){
+  if( sqlite3GlobalConfig.bMemstat==0 && mem3.mutex==0 ){
+    mem3.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
+  }
+  sqlite3_mutex_enter(mem3.mutex);
+}
+static void memsys3Leave(void){
+  sqlite3_mutex_leave(mem3.mutex);
+}
+
+/*
+** Called when we are unable to satisfy an allocation of nBytes.
+*/
+static void memsys3OutOfMemory(int nByte){
+  if( !mem3.alarmBusy ){
+    mem3.alarmBusy = 1;
+    assert( sqlite3_mutex_held(mem3.mutex) );
+    sqlite3_mutex_leave(mem3.mutex);
+    sqlite3_release_memory(nByte);
+    sqlite3_mutex_enter(mem3.mutex);
+    mem3.alarmBusy = 0;
+  }
+}
+
+
+/*
+** Chunk i is a free chunk that has been unlinked.  Adjust its 
+** size parameters for check-out and return a pointer to the 
+** user portion of the chunk.
+*/
+static void *memsys3Checkout(u32 i, u32 nBlock){
+  u32 x;
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  assert( i>=1 );
+  assert( mem3.aPool[i-1].u.hdr.size4x/4==nBlock );
+  assert( mem3.aPool[i+nBlock-1].u.hdr.prevSize==nBlock );
+  x = mem3.aPool[i-1].u.hdr.size4x;
+  mem3.aPool[i-1].u.hdr.size4x = nBlock*4 | 1 | (x&2);
+  mem3.aPool[i+nBlock-1].u.hdr.prevSize = nBlock;
+  mem3.aPool[i+nBlock-1].u.hdr.size4x |= 2;
+  return &mem3.aPool[i];
+}
+
+/*
+** Carve a piece off of the end of the mem3.iMaster free chunk.
+** Return a pointer to the new allocation.  Or, if the master chunk
+** is not large enough, return 0.
+*/
+static void *memsys3FromMaster(u32 nBlock){
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  assert( mem3.szMaster>=nBlock );
+  if( nBlock>=mem3.szMaster-1 ){
+    /* Use the entire master */
+    void *p = memsys3Checkout(mem3.iMaster, mem3.szMaster);
+    mem3.iMaster = 0;
+    mem3.szMaster = 0;
+    mem3.mnMaster = 0;
+    return p;
+  }else{
+    /* Split the master block.  Return the tail. */
+    u32 newi, x;
+    newi = mem3.iMaster + mem3.szMaster - nBlock;
+    assert( newi > mem3.iMaster+1 );
+    mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.prevSize = nBlock;
+    mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.size4x |= 2;
+    mem3.aPool[newi-1].u.hdr.size4x = nBlock*4 + 1;
+    mem3.szMaster -= nBlock;
+    mem3.aPool[newi-1].u.hdr.prevSize = mem3.szMaster;
+    x = mem3.aPool[mem3.iMaster-1].u.hdr.size4x & 2;
+    mem3.aPool[mem3.iMaster-1].u.hdr.size4x = mem3.szMaster*4 | x;
+    if( mem3.szMaster < mem3.mnMaster ){
+      mem3.mnMaster = mem3.szMaster;
+    }
+    return (void*)&mem3.aPool[newi];
+  }
+}
+
+/*
+** *pRoot is the head of a list of free chunks of the same size
+** or same size hash.  In other words, *pRoot is an entry in either
+** mem3.aiSmall[] or mem3.aiHash[].  
+**
+** This routine examines all entries on the given list and tries
+** to coalesce each entries with adjacent free chunks.  
+**
+** If it sees a chunk that is larger than mem3.iMaster, it replaces 
+** the current mem3.iMaster with the new larger chunk.  In order for
+** this mem3.iMaster replacement to work, the master chunk must be
+** linked into the hash tables.  That is not the normal state of
+** affairs, of course.  The calling routine must link the master
+** chunk before invoking this routine, then must unlink the (possibly
+** changed) master chunk once this routine has finished.
+*/
+static void memsys3Merge(u32 *pRoot){
+  u32 iNext, prev, size, i, x;
+
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  for(i=*pRoot; i>0; i=iNext){
+    iNext = mem3.aPool[i].u.list.next;
+    size = mem3.aPool[i-1].u.hdr.size4x;
+    assert( (size&1)==0 );
+    if( (size&2)==0 ){
+      memsys3UnlinkFromList(i, pRoot);
+      assert( i > mem3.aPool[i-1].u.hdr.prevSize );
+      prev = i - mem3.aPool[i-1].u.hdr.prevSize;
+      if( prev==iNext ){
+        iNext = mem3.aPool[prev].u.list.next;
+      }
+      memsys3Unlink(prev);
+      size = i + size/4 - prev;
+      x = mem3.aPool[prev-1].u.hdr.size4x & 2;
+      mem3.aPool[prev-1].u.hdr.size4x = size*4 | x;
+      mem3.aPool[prev+size-1].u.hdr.prevSize = size;
+      memsys3Link(prev);
+      i = prev;
+    }else{
+      size /= 4;
+    }
+    if( size>mem3.szMaster ){
+      mem3.iMaster = i;
+      mem3.szMaster = size;
+    }
+  }
+}
+
+/*
+** Return a block of memory of at least nBytes in size.
+** Return NULL if unable.
+**
+** This function assumes that the necessary mutexes, if any, are
+** already held by the caller. Hence "Unsafe".
+*/
+static void *memsys3MallocUnsafe(int nByte){
+  u32 i;
+  u32 nBlock;
+  u32 toFree;
+
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  assert( sizeof(Mem3Block)==8 );
+  if( nByte<=12 ){
+    nBlock = 2;
+  }else{
+    nBlock = (nByte + 11)/8;
+  }
+  assert( nBlock>=2 );
+
+  /* STEP 1:
+  ** Look for an entry of the correct size in either the small
+  ** chunk table or in the large chunk hash table.  This is
+  ** successful most of the time (about 9 times out of 10).
+  */
+  if( nBlock <= MX_SMALL ){
+    i = mem3.aiSmall[nBlock-2];
+    if( i>0 ){
+      memsys3UnlinkFromList(i, &mem3.aiSmall[nBlock-2]);
+      return memsys3Checkout(i, nBlock);
+    }
+  }else{
+    int hash = nBlock % N_HASH;
+    for(i=mem3.aiHash[hash]; i>0; i=mem3.aPool[i].u.list.next){
+      if( mem3.aPool[i-1].u.hdr.size4x/4==nBlock ){
+        memsys3UnlinkFromList(i, &mem3.aiHash[hash]);
+        return memsys3Checkout(i, nBlock);
+      }
+    }
+  }
+
+  /* STEP 2:
+  ** Try to satisfy the allocation by carving a piece off of the end
+  ** of the master chunk.  This step usually works if step 1 fails.
+  */
+  if( mem3.szMaster>=nBlock ){
+    return memsys3FromMaster(nBlock);
+  }
+
+
+  /* STEP 3:  
+  ** Loop through the entire memory pool.  Coalesce adjacent free
+  ** chunks.  Recompute the master chunk as the largest free chunk.
+  ** Then try again to satisfy the allocation by carving a piece off
+  ** of the end of the master chunk.  This step happens very
+  ** rarely (we hope!)
+  */
+  for(toFree=nBlock*16; toFree<(mem3.nPool*16); toFree *= 2){
+    memsys3OutOfMemory(toFree);
+    if( mem3.iMaster ){
+      memsys3Link(mem3.iMaster);
+      mem3.iMaster = 0;
+      mem3.szMaster = 0;
+    }
+    for(i=0; i<N_HASH; i++){
+      memsys3Merge(&mem3.aiHash[i]);
+    }
+    for(i=0; i<MX_SMALL-1; i++){
+      memsys3Merge(&mem3.aiSmall[i]);
+    }
+    if( mem3.szMaster ){
+      memsys3Unlink(mem3.iMaster);
+      if( mem3.szMaster>=nBlock ){
+        return memsys3FromMaster(nBlock);
+      }
+    }
+  }
+
+  /* If none of the above worked, then we fail. */
+  return 0;
+}
+
+/*
+** Free an outstanding memory allocation.
+**
+** This function assumes that the necessary mutexes, if any, are
+** already held by the caller. Hence "Unsafe".
+*/
+static void memsys3FreeUnsafe(void *pOld){
+  Mem3Block *p = (Mem3Block*)pOld;
+  int i;
+  u32 size, x;
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  assert( p>mem3.aPool && p<&mem3.aPool[mem3.nPool] );
+  i = p - mem3.aPool;
+  assert( (mem3.aPool[i-1].u.hdr.size4x&1)==1 );
+  size = mem3.aPool[i-1].u.hdr.size4x/4;
+  assert( i+size<=mem3.nPool+1 );
+  mem3.aPool[i-1].u.hdr.size4x &= ~1;
+  mem3.aPool[i+size-1].u.hdr.prevSize = size;
+  mem3.aPool[i+size-1].u.hdr.size4x &= ~2;
+  memsys3Link(i);
+
+  /* Try to expand the master using the newly freed chunk */
+  if( mem3.iMaster ){
+    while( (mem3.aPool[mem3.iMaster-1].u.hdr.size4x&2)==0 ){
+      size = mem3.aPool[mem3.iMaster-1].u.hdr.prevSize;
+      mem3.iMaster -= size;
+      mem3.szMaster += size;
+      memsys3Unlink(mem3.iMaster);
+      x = mem3.aPool[mem3.iMaster-1].u.hdr.size4x & 2;
+      mem3.aPool[mem3.iMaster-1].u.hdr.size4x = mem3.szMaster*4 | x;
+      mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.prevSize = mem3.szMaster;
+    }
+    x = mem3.aPool[mem3.iMaster-1].u.hdr.size4x & 2;
+    while( (mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.size4x&1)==0 ){
+      memsys3Unlink(mem3.iMaster+mem3.szMaster);
+      mem3.szMaster += mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.size4x/4;
+      mem3.aPool[mem3.iMaster-1].u.hdr.size4x = mem3.szMaster*4 | x;
+      mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.prevSize = mem3.szMaster;
+    }
+  }
+}
+
+/*
+** Return the size of an outstanding allocation, in bytes.  The
+** size returned omits the 8-byte header overhead.  This only
+** works for chunks that are currently checked out.
+*/
+static int memsys3Size(void *p){
+  Mem3Block *pBlock;
+  assert( p!=0 );
+  pBlock = (Mem3Block*)p;
+  assert( (pBlock[-1].u.hdr.size4x&1)!=0 );
+  return (pBlock[-1].u.hdr.size4x&~3)*2 - 4;
+}
+
+/*
+** Round up a request size to the next valid allocation size.
+*/
+static int memsys3Roundup(int n){
+  if( n<=12 ){
+    return 12;
+  }else{
+    return ((n+11)&~7) - 4;
+  }
+}
+
+/*
+** Allocate nBytes of memory.
+*/
+static void *memsys3Malloc(int nBytes){
+  sqlite3_int64 *p;
+  assert( nBytes>0 );          /* malloc.c filters out 0 byte requests */
+  memsys3Enter();
+  p = memsys3MallocUnsafe(nBytes);
+  memsys3Leave();
+  return (void*)p; 
+}
+
+/*
+** Free memory.
+*/
+static void memsys3Free(void *pPrior){
+  assert( pPrior );
+  memsys3Enter();
+  memsys3FreeUnsafe(pPrior);
+  memsys3Leave();
+}
+
+/*
+** Change the size of an existing memory allocation
+*/
+static void *memsys3Realloc(void *pPrior, int nBytes){
+  int nOld;
+  void *p;
+  if( pPrior==0 ){
+    return sqlite3_malloc(nBytes);
+  }
+  if( nBytes<=0 ){
+    sqlite3_free(pPrior);
+    return 0;
+  }
+  nOld = memsys3Size(pPrior);
+  if( nBytes<=nOld && nBytes>=nOld-128 ){
+    return pPrior;
+  }
+  memsys3Enter();
+  p = memsys3MallocUnsafe(nBytes);
+  if( p ){
+    if( nOld<nBytes ){
+      memcpy(p, pPrior, nOld);
+    }else{
+      memcpy(p, pPrior, nBytes);
+    }
+    memsys3FreeUnsafe(pPrior);
+  }
+  memsys3Leave();
+  return p;
+}
+
+/*
+** Initialize this module.
+*/
+static int memsys3Init(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  if( !sqlite3GlobalConfig.pHeap ){
+    return SQLITE_ERROR;
+  }
+
+  /* Store a pointer to the memory block in global structure mem3. */
+  assert( sizeof(Mem3Block)==8 );
+  mem3.aPool = (Mem3Block *)sqlite3GlobalConfig.pHeap;
+  mem3.nPool = (sqlite3GlobalConfig.nHeap / sizeof(Mem3Block)) - 2;
+
+  /* Initialize the master block. */
+  mem3.szMaster = mem3.nPool;
+  mem3.mnMaster = mem3.szMaster;
+  mem3.iMaster = 1;
+  mem3.aPool[0].u.hdr.size4x = (mem3.szMaster<<2) + 2;
+  mem3.aPool[mem3.nPool].u.hdr.prevSize = mem3.nPool;
+  mem3.aPool[mem3.nPool].u.hdr.size4x = 1;
+
+  return SQLITE_OK;
+}
+
+/*
+** Deinitialize this module.
+*/
+static void memsys3Shutdown(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  mem3.mutex = 0;
+  return;
+}
+
+
+
+/*
+** Open the file indicated and write a log of all unfreed memory 
+** allocations into that log.
+*/
+SQLITE_PRIVATE void sqlite3Memsys3Dump(const char *zFilename){
+#ifdef SQLITE_DEBUG
+  FILE *out;
+  u32 i, j;
+  u32 size;
+  if( zFilename==0 || zFilename[0]==0 ){
+    out = stdout;
+  }else{
+    out = fopen(zFilename, "w");
+    if( out==0 ){
+      fprintf(stderr, "** Unable to output memory debug output log: %s **\n",
+                      zFilename);
+      return;
+    }
+  }
+  memsys3Enter();
+  fprintf(out, "CHUNKS:\n");
+  for(i=1; i<=mem3.nPool; i+=size/4){
+    size = mem3.aPool[i-1].u.hdr.size4x;
+    if( size/4<=1 ){
+      fprintf(out, "%p size error\n", &mem3.aPool[i]);
+      assert( 0 );
+      break;
+    }
+    if( (size&1)==0 && mem3.aPool[i+size/4-1].u.hdr.prevSize!=size/4 ){
+      fprintf(out, "%p tail size does not match\n", &mem3.aPool[i]);
+      assert( 0 );
+      break;
+    }
+    if( ((mem3.aPool[i+size/4-1].u.hdr.size4x&2)>>1)!=(size&1) ){
+      fprintf(out, "%p tail checkout bit is incorrect\n", &mem3.aPool[i]);
+      assert( 0 );
+      break;
+    }
+    if( size&1 ){
+      fprintf(out, "%p %6d bytes checked out\n", &mem3.aPool[i], (size/4)*8-8);
+    }else{
+      fprintf(out, "%p %6d bytes free%s\n", &mem3.aPool[i], (size/4)*8-8,
+                  i==mem3.iMaster ? " **master**" : "");
+    }
+  }
+  for(i=0; i<MX_SMALL-1; i++){
+    if( mem3.aiSmall[i]==0 ) continue;
+    fprintf(out, "small(%2d):", i);
+    for(j = mem3.aiSmall[i]; j>0; j=mem3.aPool[j].u.list.next){
+      fprintf(out, " %p(%d)", &mem3.aPool[j],
+              (mem3.aPool[j-1].u.hdr.size4x/4)*8-8);
+    }
+    fprintf(out, "\n"); 
+  }
+  for(i=0; i<N_HASH; i++){
+    if( mem3.aiHash[i]==0 ) continue;
+    fprintf(out, "hash(%2d):", i);
+    for(j = mem3.aiHash[i]; j>0; j=mem3.aPool[j].u.list.next){
+      fprintf(out, " %p(%d)", &mem3.aPool[j],
+              (mem3.aPool[j-1].u.hdr.size4x/4)*8-8);
+    }
+    fprintf(out, "\n"); 
+  }
+  fprintf(out, "master=%d\n", mem3.iMaster);
+  fprintf(out, "nowUsed=%d\n", mem3.nPool*8 - mem3.szMaster*8);
+  fprintf(out, "mxUsed=%d\n", mem3.nPool*8 - mem3.mnMaster*8);
+  sqlite3_mutex_leave(mem3.mutex);
+  if( out==stdout ){
+    fflush(stdout);
+  }else{
+    fclose(out);
+  }
+#else
+  UNUSED_PARAMETER(zFilename);
+#endif
+}
+
+/*
+** This routine is the only routine in this file with external 
+** linkage.
+**
+** Populate the low-level memory allocation function pointers in
+** sqlite3GlobalConfig.m with pointers to the routines in this file. The
+** arguments specify the block of memory to manage.
+**
+** This routine is only called by sqlite3_config(), and therefore
+** is not required to be threadsafe (it is not).
+*/
+SQLITE_PRIVATE const sqlite3_mem_methods *sqlite3MemGetMemsys3(void){
+  static const sqlite3_mem_methods mempoolMethods = {
+     memsys3Malloc,
+     memsys3Free,
+     memsys3Realloc,
+     memsys3Size,
+     memsys3Roundup,
+     memsys3Init,
+     memsys3Shutdown,
+     0
+  };
+  return &mempoolMethods;
+}
+
+#endif /* SQLITE_ENABLE_MEMSYS3 */
+
+/************** End of mem3.c ************************************************/
+/************** Begin file mem5.c ********************************************/
+/*
+** 2007 October 14
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C functions that implement a memory
+** allocation subsystem for use by SQLite. 
+**
+** This version of the memory allocation subsystem omits all
+** use of malloc(). The application gives SQLite a block of memory
+** before calling sqlite3_initialize() from which allocations
+** are made and returned by the xMalloc() and xRealloc() 
+** implementations. Once sqlite3_initialize() has been called,
+** the amount of memory available to SQLite is fixed and cannot
+** be changed.
+**
+** This version of the memory allocation subsystem is included
+** in the build only if SQLITE_ENABLE_MEMSYS5 is defined.
+**
+** This memory allocator uses the following algorithm:
+**
+**   1.  All memory allocation sizes are rounded up to a power of 2.
+**
+**   2.  If two adjacent free blocks are the halves of a larger block,
+**       then the two blocks are coalesced into the single larger block.
+**
+**   3.  New memory is allocated from the first available free block.
+**
+** This algorithm is described in: J. M. Robson. "Bounds for Some Functions
+** Concerning Dynamic Storage Allocation". Journal of the Association for
+** Computing Machinery, Volume 21, Number 8, July 1974, pages 491-499.
+** 
+** Let n be the size of the largest allocation divided by the minimum
+** allocation size (after rounding all sizes up to a power of 2.)  Let M
+** be the maximum amount of memory ever outstanding at one time.  Let
+** N be the total amount of memory available for allocation.  Robson
+** proved that this memory allocator will never breakdown due to 
+** fragmentation as long as the following constraint holds:
+**
+**      N >=  M*(1 + log2(n)/2) - n + 1
+**
+** The sqlite3_status() logic tracks the maximum values of n and M so
+** that an application can, at any time, verify this constraint.
+*/
+/* #include "sqliteInt.h" */
+
+/*
+** This version of the memory allocator is used only when 
+** SQLITE_ENABLE_MEMSYS5 is defined.
+*/
+#ifdef SQLITE_ENABLE_MEMSYS5
+
+/*
+** A minimum allocation is an instance of the following structure.
+** Larger allocations are an array of these structures where the
+** size of the array is a power of 2.
+**
+** The size of this object must be a power of two.  That fact is
+** verified in memsys5Init().
+*/
+typedef struct Mem5Link Mem5Link;
+struct Mem5Link {
+  int next;       /* Index of next free chunk */
+  int prev;       /* Index of previous free chunk */
+};
+
+/*
+** Maximum size of any allocation is ((1<<LOGMAX)*mem5.szAtom). Since
+** mem5.szAtom is always at least 8 and 32-bit integers are used,
+** it is not actually possible to reach this limit.
+*/
+#define LOGMAX 30
+
+/*
+** Masks used for mem5.aCtrl[] elements.
+*/
+#define CTRL_LOGSIZE  0x1f    /* Log2 Size of this block */
+#define CTRL_FREE     0x20    /* True if not checked out */
+
+/*
+** All of the static variables used by this module are collected
+** into a single structure named "mem5".  This is to keep the
+** static variables organized and to reduce namespace pollution
+** when this module is combined with other in the amalgamation.
+*/
+static SQLITE_WSD struct Mem5Global {
+  /*
+  ** Memory available for allocation
+  */
+  int szAtom;      /* Smallest possible allocation in bytes */
+  int nBlock;      /* Number of szAtom sized blocks in zPool */
+  u8 *zPool;       /* Memory available to be allocated */
+  
+  /*
+  ** Mutex to control access to the memory allocation subsystem.
+  */
+  sqlite3_mutex *mutex;
+
+#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
+  /*
+  ** Performance statistics
+  */
+  u64 nAlloc;         /* Total number of calls to malloc */
+  u64 totalAlloc;     /* Total of all malloc calls - includes internal frag */
+  u64 totalExcess;    /* Total internal fragmentation */
+  u32 currentOut;     /* Current checkout, including internal fragmentation */
+  u32 currentCount;   /* Current number of distinct checkouts */
+  u32 maxOut;         /* Maximum instantaneous currentOut */
+  u32 maxCount;       /* Maximum instantaneous currentCount */
+  u32 maxRequest;     /* Largest allocation (exclusive of internal frag) */
+#endif
+  
+  /*
+  ** Lists of free blocks.  aiFreelist[0] is a list of free blocks of
+  ** size mem5.szAtom.  aiFreelist[1] holds blocks of size szAtom*2.
+  ** aiFreelist[2] holds free blocks of size szAtom*4.  And so forth.
+  */
+  int aiFreelist[LOGMAX+1];
+
+  /*
+  ** Space for tracking which blocks are checked out and the size
+  ** of each block.  One byte per block.
+  */
+  u8 *aCtrl;
+
+} mem5;
+
+/*
+** Access the static variable through a macro for SQLITE_OMIT_WSD.
+*/
+#define mem5 GLOBAL(struct Mem5Global, mem5)
+
+/*
+** Assuming mem5.zPool is divided up into an array of Mem5Link
+** structures, return a pointer to the idx-th such link.
+*/
+#define MEM5LINK(idx) ((Mem5Link *)(&mem5.zPool[(idx)*mem5.szAtom]))
+
+/*
+** Unlink the chunk at mem5.aPool[i] from list it is currently
+** on.  It should be found on mem5.aiFreelist[iLogsize].
+*/
+static void memsys5Unlink(int i, int iLogsize){
+  int next, prev;
+  assert( i>=0 && i<mem5.nBlock );
+  assert( iLogsize>=0 && iLogsize<=LOGMAX );
+  assert( (mem5.aCtrl[i] & CTRL_LOGSIZE)==iLogsize );
+
+  next = MEM5LINK(i)->next;
+  prev = MEM5LINK(i)->prev;
+  if( prev<0 ){
+    mem5.aiFreelist[iLogsize] = next;
+  }else{
+    MEM5LINK(prev)->next = next;
+  }
+  if( next>=0 ){
+    MEM5LINK(next)->prev = prev;
+  }
+}
+
+/*
+** Link the chunk at mem5.aPool[i] so that is on the iLogsize
+** free list.
+*/
+static void memsys5Link(int i, int iLogsize){
+  int x;
+  assert( sqlite3_mutex_held(mem5.mutex) );
+  assert( i>=0 && i<mem5.nBlock );
+  assert( iLogsize>=0 && iLogsize<=LOGMAX );
+  assert( (mem5.aCtrl[i] & CTRL_LOGSIZE)==iLogsize );
+
+  x = MEM5LINK(i)->next = mem5.aiFreelist[iLogsize];
+  MEM5LINK(i)->prev = -1;
+  if( x>=0 ){
+    assert( x<mem5.nBlock );
+    MEM5LINK(x)->prev = i;
+  }
+  mem5.aiFreelist[iLogsize] = i;
+}
+
+/*
+** Obtain or release the mutex needed to access global data structures.
+*/
+static void memsys5Enter(void){
+  sqlite3_mutex_enter(mem5.mutex);
+}
+static void memsys5Leave(void){
+  sqlite3_mutex_leave(mem5.mutex);
+}
+
+/*
+** Return the size of an outstanding allocation, in bytes.
+** This only works for chunks that are currently checked out.
+*/
+static int memsys5Size(void *p){
+  int iSize, i;
+  assert( p!=0 );
+  i = (int)(((u8 *)p-mem5.zPool)/mem5.szAtom);
+  assert( i>=0 && i<mem5.nBlock );
+  iSize = mem5.szAtom * (1 << (mem5.aCtrl[i]&CTRL_LOGSIZE));
+  return iSize;
+}
+
+/*
+** Return a block of memory of at least nBytes in size.
+** Return NULL if unable.  Return NULL if nBytes==0.
+**
+** The caller guarantees that nByte is positive.
+**
+** The caller has obtained a mutex prior to invoking this
+** routine so there is never any chance that two or more
+** threads can be in this routine at the same time.
+*/
+static void *memsys5MallocUnsafe(int nByte){
+  int i;           /* Index of a mem5.aPool[] slot */
+  int iBin;        /* Index into mem5.aiFreelist[] */
+  int iFullSz;     /* Size of allocation rounded up to power of 2 */
+  int iLogsize;    /* Log2 of iFullSz/POW2_MIN */
+
+  /* nByte must be a positive */
+  assert( nByte>0 );
+
+  /* No more than 1GiB per allocation */
+  if( nByte > 0x40000000 ) return 0;
+
+#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
+  /* Keep track of the maximum allocation request.  Even unfulfilled
+  ** requests are counted */
+  if( (u32)nByte>mem5.maxRequest ){
+    mem5.maxRequest = nByte;
+  }
+#endif
+
+
+  /* Round nByte up to the next valid power of two */
+  for(iFullSz=mem5.szAtom,iLogsize=0; iFullSz<nByte; iFullSz*=2,iLogsize++){}
+
+  /* Make sure mem5.aiFreelist[iLogsize] contains at least one free
+  ** block.  If not, then split a block of the next larger power of
+  ** two in order to create a new free block of size iLogsize.
+  */
+  for(iBin=iLogsize; iBin<=LOGMAX && mem5.aiFreelist[iBin]<0; iBin++){}
+  if( iBin>LOGMAX ){
+    testcase( sqlite3GlobalConfig.xLog!=0 );
+    sqlite3_log(SQLITE_NOMEM, "failed to allocate %u bytes", nByte);
+    return 0;
+  }
+  i = mem5.aiFreelist[iBin];
+  memsys5Unlink(i, iBin);
+  while( iBin>iLogsize ){
+    int newSize;
+
+    iBin--;
+    newSize = 1 << iBin;
+    mem5.aCtrl[i+newSize] = CTRL_FREE | iBin;
+    memsys5Link(i+newSize, iBin);
+  }
+  mem5.aCtrl[i] = iLogsize;
+
+#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
+  /* Update allocator performance statistics. */
+  mem5.nAlloc++;
+  mem5.totalAlloc += iFullSz;
+  mem5.totalExcess += iFullSz - nByte;
+  mem5.currentCount++;
+  mem5.currentOut += iFullSz;
+  if( mem5.maxCount<mem5.currentCount ) mem5.maxCount = mem5.currentCount;
+  if( mem5.maxOut<mem5.currentOut ) mem5.maxOut = mem5.currentOut;
+#endif
+
+#ifdef SQLITE_DEBUG
+  /* Make sure the allocated memory does not assume that it is set to zero
+  ** or retains a value from a previous allocation */
+  memset(&mem5.zPool[i*mem5.szAtom], 0xAA, iFullSz);
+#endif
+
+  /* Return a pointer to the allocated memory. */
+  return (void*)&mem5.zPool[i*mem5.szAtom];
+}
+
+/*
+** Free an outstanding memory allocation.
+*/
+static void memsys5FreeUnsafe(void *pOld){
+  u32 size, iLogsize;
+  int iBlock;
+
+  /* Set iBlock to the index of the block pointed to by pOld in 
+  ** the array of mem5.szAtom byte blocks pointed to by mem5.zPool.
+  */
+  iBlock = (int)(((u8 *)pOld-mem5.zPool)/mem5.szAtom);
+
+  /* Check that the pointer pOld points to a valid, non-free block. */
+  assert( iBlock>=0 && iBlock<mem5.nBlock );
+  assert( ((u8 *)pOld-mem5.zPool)%mem5.szAtom==0 );
+  assert( (mem5.aCtrl[iBlock] & CTRL_FREE)==0 );
+
+  iLogsize = mem5.aCtrl[iBlock] & CTRL_LOGSIZE;
+  size = 1<<iLogsize;
+  assert( iBlock+size-1<(u32)mem5.nBlock );
+
+  mem5.aCtrl[iBlock] |= CTRL_FREE;
+  mem5.aCtrl[iBlock+size-1] |= CTRL_FREE;
+
+#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
+  assert( mem5.currentCount>0 );
+  assert( mem5.currentOut>=(size*mem5.szAtom) );
+  mem5.currentCount--;
+  mem5.currentOut -= size*mem5.szAtom;
+  assert( mem5.currentOut>0 || mem5.currentCount==0 );
+  assert( mem5.currentCount>0 || mem5.currentOut==0 );
+#endif
+
+  mem5.aCtrl[iBlock] = CTRL_FREE | iLogsize;
+  while( ALWAYS(iLogsize<LOGMAX) ){
+    int iBuddy;
+    if( (iBlock>>iLogsize) & 1 ){
+      iBuddy = iBlock - size;
+      assert( iBuddy>=0 );
+    }else{
+      iBuddy = iBlock + size;
+      if( iBuddy>=mem5.nBlock ) break;
+    }
+    if( mem5.aCtrl[iBuddy]!=(CTRL_FREE | iLogsize) ) break;
+    memsys5Unlink(iBuddy, iLogsize);
+    iLogsize++;
+    if( iBuddy<iBlock ){
+      mem5.aCtrl[iBuddy] = CTRL_FREE | iLogsize;
+      mem5.aCtrl[iBlock] = 0;
+      iBlock = iBuddy;
+    }else{
+      mem5.aCtrl[iBlock] = CTRL_FREE | iLogsize;
+      mem5.aCtrl[iBuddy] = 0;
+    }
+    size *= 2;
+  }
+
+#ifdef SQLITE_DEBUG
+  /* Overwrite freed memory with the 0x55 bit pattern to verify that it is
+  ** not used after being freed */
+  memset(&mem5.zPool[iBlock*mem5.szAtom], 0x55, size);
+#endif
+
+  memsys5Link(iBlock, iLogsize);
+}
+
+/*
+** Allocate nBytes of memory.
+*/
+static void *memsys5Malloc(int nBytes){
+  sqlite3_int64 *p = 0;
+  if( nBytes>0 ){
+    memsys5Enter();
+    p = memsys5MallocUnsafe(nBytes);
+    memsys5Leave();
+  }
+  return (void*)p; 
+}
+
+/*
+** Free memory.
+**
+** The outer layer memory allocator prevents this routine from
+** being called with pPrior==0.
+*/
+static void memsys5Free(void *pPrior){
+  assert( pPrior!=0 );
+  memsys5Enter();
+  memsys5FreeUnsafe(pPrior);
+  memsys5Leave();  
+}
+
+/*
+** Change the size of an existing memory allocation.
+**
+** The outer layer memory allocator prevents this routine from
+** being called with pPrior==0.  
+**
+** nBytes is always a value obtained from a prior call to
+** memsys5Round().  Hence nBytes is always a non-negative power
+** of two.  If nBytes==0 that means that an oversize allocation
+** (an allocation larger than 0x40000000) was requested and this
+** routine should return 0 without freeing pPrior.
+*/
+static void *memsys5Realloc(void *pPrior, int nBytes){
+  int nOld;
+  void *p;
+  assert( pPrior!=0 );
+  assert( (nBytes&(nBytes-1))==0 );  /* EV: R-46199-30249 */
+  assert( nBytes>=0 );
+  if( nBytes==0 ){
+    return 0;
+  }
+  nOld = memsys5Size(pPrior);
+  if( nBytes<=nOld ){
+    return pPrior;
+  }
+  p = memsys5Malloc(nBytes);
+  if( p ){
+    memcpy(p, pPrior, nOld);
+    memsys5Free(pPrior);
+  }
+  return p;
+}
+
+/*
+** Round up a request size to the next valid allocation size.  If
+** the allocation is too large to be handled by this allocation system,
+** return 0.
+**
+** All allocations must be a power of two and must be expressed by a
+** 32-bit signed integer.  Hence the largest allocation is 0x40000000
+** or 1073741824 bytes.
+*/
+static int memsys5Roundup(int n){
+  int iFullSz;
+  if( n > 0x40000000 ) return 0;
+  for(iFullSz=mem5.szAtom; iFullSz<n; iFullSz *= 2);
+  return iFullSz;
+}
+
+/*
+** Return the ceiling of the logarithm base 2 of iValue.
+**
+** Examples:   memsys5Log(1) -> 0
+**             memsys5Log(2) -> 1
+**             memsys5Log(4) -> 2
+**             memsys5Log(5) -> 3
+**             memsys5Log(8) -> 3
+**             memsys5Log(9) -> 4
+*/
+static int memsys5Log(int iValue){
+  int iLog;
+  for(iLog=0; (iLog<(int)((sizeof(int)*8)-1)) && (1<<iLog)<iValue; iLog++);
+  return iLog;
+}
+
+/*
+** Initialize the memory allocator.
+**
+** This routine is not threadsafe.  The caller must be holding a mutex
+** to prevent multiple threads from entering at the same time.
+*/
+static int memsys5Init(void *NotUsed){
+  int ii;            /* Loop counter */
+  int nByte;         /* Number of bytes of memory available to this allocator */
+  u8 *zByte;         /* Memory usable by this allocator */
+  int nMinLog;       /* Log base 2 of minimum allocation size in bytes */
+  int iOffset;       /* An offset into mem5.aCtrl[] */
+
+  UNUSED_PARAMETER(NotUsed);
+
+  /* For the purposes of this routine, disable the mutex */
+  mem5.mutex = 0;
+
+  /* The size of a Mem5Link object must be a power of two.  Verify that
+  ** this is case.
+  */
+  assert( (sizeof(Mem5Link)&(sizeof(Mem5Link)-1))==0 );
+
+  nByte = sqlite3GlobalConfig.nHeap;
+  zByte = (u8*)sqlite3GlobalConfig.pHeap;
+  assert( zByte!=0 );  /* sqlite3_config() does not allow otherwise */
+
+  /* boundaries on sqlite3GlobalConfig.mnReq are enforced in sqlite3_config() */
+  nMinLog = memsys5Log(sqlite3GlobalConfig.mnReq);
+  mem5.szAtom = (1<<nMinLog);
+  while( (int)sizeof(Mem5Link)>mem5.szAtom ){
+    mem5.szAtom = mem5.szAtom << 1;
+  }
+
+  mem5.nBlock = (nByte / (mem5.szAtom+sizeof(u8)));
+  mem5.zPool = zByte;
+  mem5.aCtrl = (u8 *)&mem5.zPool[mem5.nBlock*mem5.szAtom];
+
+  for(ii=0; ii<=LOGMAX; ii++){
+    mem5.aiFreelist[ii] = -1;
+  }
+
+  iOffset = 0;
+  for(ii=LOGMAX; ii>=0; ii--){
+    int nAlloc = (1<<ii);
+    if( (iOffset+nAlloc)<=mem5.nBlock ){
+      mem5.aCtrl[iOffset] = ii | CTRL_FREE;
+      memsys5Link(iOffset, ii);
+      iOffset += nAlloc;
+    }
+    assert((iOffset+nAlloc)>mem5.nBlock);
+  }
+
+  /* If a mutex is required for normal operation, allocate one */
+  if( sqlite3GlobalConfig.bMemstat==0 ){
+    mem5.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Deinitialize this module.
+*/
+static void memsys5Shutdown(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  mem5.mutex = 0;
+  return;
+}
+
+#ifdef SQLITE_TEST
+/*
+** Open the file indicated and write a log of all unfreed memory 
+** allocations into that log.
+*/
+SQLITE_PRIVATE void sqlite3Memsys5Dump(const char *zFilename){
+  FILE *out;
+  int i, j, n;
+  int nMinLog;
+
+  if( zFilename==0 || zFilename[0]==0 ){
+    out = stdout;
+  }else{
+    out = fopen(zFilename, "w");
+    if( out==0 ){
+      fprintf(stderr, "** Unable to output memory debug output log: %s **\n",
+                      zFilename);
+      return;
+    }
+  }
+  memsys5Enter();
+  nMinLog = memsys5Log(mem5.szAtom);
+  for(i=0; i<=LOGMAX && i+nMinLog<32; i++){
+    for(n=0, j=mem5.aiFreelist[i]; j>=0; j = MEM5LINK(j)->next, n++){}
+    fprintf(out, "freelist items of size %d: %d\n", mem5.szAtom << i, n);
+  }
+  fprintf(out, "mem5.nAlloc       = %llu\n", mem5.nAlloc);
+  fprintf(out, "mem5.totalAlloc   = %llu\n", mem5.totalAlloc);
+  fprintf(out, "mem5.totalExcess  = %llu\n", mem5.totalExcess);
+  fprintf(out, "mem5.currentOut   = %u\n", mem5.currentOut);
+  fprintf(out, "mem5.currentCount = %u\n", mem5.currentCount);
+  fprintf(out, "mem5.maxOut       = %u\n", mem5.maxOut);
+  fprintf(out, "mem5.maxCount     = %u\n", mem5.maxCount);
+  fprintf(out, "mem5.maxRequest   = %u\n", mem5.maxRequest);
+  memsys5Leave();
+  if( out==stdout ){
+    fflush(stdout);
+  }else{
+    fclose(out);
+  }
+}
+#endif
+
+/*
+** This routine is the only routine in this file with external 
+** linkage. It returns a pointer to a static sqlite3_mem_methods
+** struct populated with the memsys5 methods.
+*/
+SQLITE_PRIVATE const sqlite3_mem_methods *sqlite3MemGetMemsys5(void){
+  static const sqlite3_mem_methods memsys5Methods = {
+     memsys5Malloc,
+     memsys5Free,
+     memsys5Realloc,
+     memsys5Size,
+     memsys5Roundup,
+     memsys5Init,
+     memsys5Shutdown,
+     0
+  };
+  return &memsys5Methods;
+}
+
+#endif /* SQLITE_ENABLE_MEMSYS5 */
+
+/************** End of mem5.c ************************************************/
+/************** Begin file mutex.c *******************************************/
+/*
+** 2007 August 14
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C functions that implement mutexes.
+**
+** This file contains code that is common across all mutex implementations.
+*/
+/* #include "sqliteInt.h" */
+
+#if defined(SQLITE_DEBUG) && !defined(SQLITE_MUTEX_OMIT)
+/*
+** For debugging purposes, record when the mutex subsystem is initialized
+** and uninitialized so that we can assert() if there is an attempt to
+** allocate a mutex while the system is uninitialized.
+*/
+static SQLITE_WSD int mutexIsInit = 0;
+#endif /* SQLITE_DEBUG && !defined(SQLITE_MUTEX_OMIT) */
+
+
+#ifndef SQLITE_MUTEX_OMIT
+/*
+** Initialize the mutex system.
+*/
+SQLITE_PRIVATE int sqlite3MutexInit(void){ 
+  int rc = SQLITE_OK;
+  if( !sqlite3GlobalConfig.mutex.xMutexAlloc ){
+    /* If the xMutexAlloc method has not been set, then the user did not
+    ** install a mutex implementation via sqlite3_config() prior to 
+    ** sqlite3_initialize() being called. This block copies pointers to
+    ** the default implementation into the sqlite3GlobalConfig structure.
+    */
+    sqlite3_mutex_methods const *pFrom;
+    sqlite3_mutex_methods *pTo = &sqlite3GlobalConfig.mutex;
+
+    if( sqlite3GlobalConfig.bCoreMutex ){
+      pFrom = sqlite3DefaultMutex();
+    }else{
+      pFrom = sqlite3NoopMutex();
+    }
+    pTo->xMutexInit = pFrom->xMutexInit;
+    pTo->xMutexEnd = pFrom->xMutexEnd;
+    pTo->xMutexFree = pFrom->xMutexFree;
+    pTo->xMutexEnter = pFrom->xMutexEnter;
+    pTo->xMutexTry = pFrom->xMutexTry;
+    pTo->xMutexLeave = pFrom->xMutexLeave;
+    pTo->xMutexHeld = pFrom->xMutexHeld;
+    pTo->xMutexNotheld = pFrom->xMutexNotheld;
+    sqlite3MemoryBarrier();
+    pTo->xMutexAlloc = pFrom->xMutexAlloc;
+  }
+  assert( sqlite3GlobalConfig.mutex.xMutexInit );
+  rc = sqlite3GlobalConfig.mutex.xMutexInit();
+
+#ifdef SQLITE_DEBUG
+  GLOBAL(int, mutexIsInit) = 1;
+#endif
+
+  return rc;
+}
+
+/*
+** Shutdown the mutex system. This call frees resources allocated by
+** sqlite3MutexInit().
+*/
+SQLITE_PRIVATE int sqlite3MutexEnd(void){
+  int rc = SQLITE_OK;
+  if( sqlite3GlobalConfig.mutex.xMutexEnd ){
+    rc = sqlite3GlobalConfig.mutex.xMutexEnd();
+  }
+
+#ifdef SQLITE_DEBUG
+  GLOBAL(int, mutexIsInit) = 0;
+#endif
+
+  return rc;
+}
+
+/*
+** Retrieve a pointer to a static mutex or allocate a new dynamic one.
+*/
+SQLITE_API sqlite3_mutex *sqlite3_mutex_alloc(int id){
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( id<=SQLITE_MUTEX_RECURSIVE && sqlite3_initialize() ) return 0;
+  if( id>SQLITE_MUTEX_RECURSIVE && sqlite3MutexInit() ) return 0;
+#endif
+  assert( sqlite3GlobalConfig.mutex.xMutexAlloc );
+  return sqlite3GlobalConfig.mutex.xMutexAlloc(id);
+}
+
+SQLITE_PRIVATE sqlite3_mutex *sqlite3MutexAlloc(int id){
+  if( !sqlite3GlobalConfig.bCoreMutex ){
+    return 0;
+  }
+  assert( GLOBAL(int, mutexIsInit) );
+  assert( sqlite3GlobalConfig.mutex.xMutexAlloc );
+  return sqlite3GlobalConfig.mutex.xMutexAlloc(id);
+}
+
+/*
+** Free a dynamic mutex.
+*/
+SQLITE_API void sqlite3_mutex_free(sqlite3_mutex *p){
+  if( p ){
+    assert( sqlite3GlobalConfig.mutex.xMutexFree );
+    sqlite3GlobalConfig.mutex.xMutexFree(p);
+  }
+}
+
+/*
+** Obtain the mutex p. If some other thread already has the mutex, block
+** until it can be obtained.
+*/
+SQLITE_API void sqlite3_mutex_enter(sqlite3_mutex *p){
+  if( p ){
+    assert( sqlite3GlobalConfig.mutex.xMutexEnter );
+    sqlite3GlobalConfig.mutex.xMutexEnter(p);
+  }
+}
+
+/*
+** Obtain the mutex p. If successful, return SQLITE_OK. Otherwise, if another
+** thread holds the mutex and it cannot be obtained, return SQLITE_BUSY.
+*/
+SQLITE_API int sqlite3_mutex_try(sqlite3_mutex *p){
+  int rc = SQLITE_OK;
+  if( p ){
+    assert( sqlite3GlobalConfig.mutex.xMutexTry );
+    return sqlite3GlobalConfig.mutex.xMutexTry(p);
+  }
+  return rc;
+}
+
+/*
+** The sqlite3_mutex_leave() routine exits a mutex that was previously
+** entered by the same thread.  The behavior is undefined if the mutex 
+** is not currently entered. If a NULL pointer is passed as an argument
+** this function is a no-op.
+*/
+SQLITE_API void sqlite3_mutex_leave(sqlite3_mutex *p){
+  if( p ){
+    assert( sqlite3GlobalConfig.mutex.xMutexLeave );
+    sqlite3GlobalConfig.mutex.xMutexLeave(p);
+  }
+}
+
+#ifndef NDEBUG
+/*
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
+** intended for use inside assert() statements.
+*/
+SQLITE_API int sqlite3_mutex_held(sqlite3_mutex *p){
+  assert( p==0 || sqlite3GlobalConfig.mutex.xMutexHeld );
+  return p==0 || sqlite3GlobalConfig.mutex.xMutexHeld(p);
+}
+SQLITE_API int sqlite3_mutex_notheld(sqlite3_mutex *p){
+  assert( p==0 || sqlite3GlobalConfig.mutex.xMutexNotheld );
+  return p==0 || sqlite3GlobalConfig.mutex.xMutexNotheld(p);
+}
+#endif
+
+#endif /* !defined(SQLITE_MUTEX_OMIT) */
+
+/************** End of mutex.c ***********************************************/
+/************** Begin file mutex_noop.c **************************************/
+/*
+** 2008 October 07
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C functions that implement mutexes.
+**
+** This implementation in this file does not provide any mutual
+** exclusion and is thus suitable for use only in applications
+** that use SQLite in a single thread.  The routines defined
+** here are place-holders.  Applications can substitute working
+** mutex routines at start-time using the
+**
+**     sqlite3_config(SQLITE_CONFIG_MUTEX,...)
+**
+** interface.
+**
+** If compiled with SQLITE_DEBUG, then additional logic is inserted
+** that does error checking on mutexes to make sure they are being
+** called correctly.
+*/
+/* #include "sqliteInt.h" */
+
+#ifndef SQLITE_MUTEX_OMIT
+
+#ifndef SQLITE_DEBUG
+/*
+** Stub routines for all mutex methods.
+**
+** This routines provide no mutual exclusion or error checking.
+*/
+static int noopMutexInit(void){ return SQLITE_OK; }
+static int noopMutexEnd(void){ return SQLITE_OK; }
+static sqlite3_mutex *noopMutexAlloc(int id){ 
+  UNUSED_PARAMETER(id);
+  return (sqlite3_mutex*)8; 
+}
+static void noopMutexFree(sqlite3_mutex *p){ UNUSED_PARAMETER(p); return; }
+static void noopMutexEnter(sqlite3_mutex *p){ UNUSED_PARAMETER(p); return; }
+static int noopMutexTry(sqlite3_mutex *p){
+  UNUSED_PARAMETER(p);
+  return SQLITE_OK;
+}
+static void noopMutexLeave(sqlite3_mutex *p){ UNUSED_PARAMETER(p); return; }
+
+SQLITE_PRIVATE sqlite3_mutex_methods const *sqlite3NoopMutex(void){
+  static const sqlite3_mutex_methods sMutex = {
+    noopMutexInit,
+    noopMutexEnd,
+    noopMutexAlloc,
+    noopMutexFree,
+    noopMutexEnter,
+    noopMutexTry,
+    noopMutexLeave,
+
+    0,
+    0,
+  };
+
+  return &sMutex;
+}
+#endif /* !SQLITE_DEBUG */
+
+#ifdef SQLITE_DEBUG
+/*
+** In this implementation, error checking is provided for testing
+** and debugging purposes.  The mutexes still do not provide any
+** mutual exclusion.
+*/
+
+/*
+** The mutex object
+*/
+typedef struct sqlite3_debug_mutex {
+  int id;     /* The mutex type */
+  int cnt;    /* Number of entries without a matching leave */
+} sqlite3_debug_mutex;
+
+/*
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
+** intended for use inside assert() statements.
+*/
+static int debugMutexHeld(sqlite3_mutex *pX){
+  sqlite3_debug_mutex *p = (sqlite3_debug_mutex*)pX;
+  return p==0 || p->cnt>0;
+}
+static int debugMutexNotheld(sqlite3_mutex *pX){
+  sqlite3_debug_mutex *p = (sqlite3_debug_mutex*)pX;
+  return p==0 || p->cnt==0;
+}
+
+/*
+** Initialize and deinitialize the mutex subsystem.
+*/
+static int debugMutexInit(void){ return SQLITE_OK; }
+static int debugMutexEnd(void){ return SQLITE_OK; }
+
+/*
+** The sqlite3_mutex_alloc() routine allocates a new
+** mutex and returns a pointer to it.  If it returns NULL
+** that means that a mutex could not be allocated. 
+*/
+static sqlite3_mutex *debugMutexAlloc(int id){
+  static sqlite3_debug_mutex aStatic[SQLITE_MUTEX_STATIC_VFS3 - 1];
+  sqlite3_debug_mutex *pNew = 0;
+  switch( id ){
+    case SQLITE_MUTEX_FAST:
+    case SQLITE_MUTEX_RECURSIVE: {
+      pNew = sqlite3Malloc(sizeof(*pNew));
+      if( pNew ){
+        pNew->id = id;
+        pNew->cnt = 0;
+      }
+      break;
+    }
+    default: {
+#ifdef SQLITE_ENABLE_API_ARMOR
+      if( id-2<0 || id-2>=ArraySize(aStatic) ){
+        (void)SQLITE_MISUSE_BKPT;
+        return 0;
+      }
+#endif
+      pNew = &aStatic[id-2];
+      pNew->id = id;
+      break;
+    }
+  }
+  return (sqlite3_mutex*)pNew;
+}
+
+/*
+** This routine deallocates a previously allocated mutex.
+*/
+static void debugMutexFree(sqlite3_mutex *pX){
+  sqlite3_debug_mutex *p = (sqlite3_debug_mutex*)pX;
+  assert( p->cnt==0 );
+  if( p->id==SQLITE_MUTEX_RECURSIVE || p->id==SQLITE_MUTEX_FAST ){
+    sqlite3_free(p);
+  }else{
+#ifdef SQLITE_ENABLE_API_ARMOR
+    (void)SQLITE_MISUSE_BKPT;
+#endif
+  }
+}
+
+/*
+** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
+** to enter a mutex.  If another thread is already within the mutex,
+** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
+** SQLITE_BUSY.  The sqlite3_mutex_try() interface returns SQLITE_OK
+** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
+** be entered multiple times by the same thread.  In such cases the,
+** mutex must be exited an equal number of times before another thread
+** can enter.  If the same thread tries to enter any other kind of mutex
+** more than once, the behavior is undefined.
+*/
+static void debugMutexEnter(sqlite3_mutex *pX){
+  sqlite3_debug_mutex *p = (sqlite3_debug_mutex*)pX;
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || debugMutexNotheld(pX) );
+  p->cnt++;
+}
+static int debugMutexTry(sqlite3_mutex *pX){
+  sqlite3_debug_mutex *p = (sqlite3_debug_mutex*)pX;
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || debugMutexNotheld(pX) );
+  p->cnt++;
+  return SQLITE_OK;
+}
+
+/*
+** The sqlite3_mutex_leave() routine exits a mutex that was
+** previously entered by the same thread.  The behavior
+** is undefined if the mutex is not currently entered or
+** is not currently allocated.  SQLite will never do either.
+*/
+static void debugMutexLeave(sqlite3_mutex *pX){
+  sqlite3_debug_mutex *p = (sqlite3_debug_mutex*)pX;
+  assert( debugMutexHeld(pX) );
+  p->cnt--;
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || debugMutexNotheld(pX) );
+}
+
+SQLITE_PRIVATE sqlite3_mutex_methods const *sqlite3NoopMutex(void){
+  static const sqlite3_mutex_methods sMutex = {
+    debugMutexInit,
+    debugMutexEnd,
+    debugMutexAlloc,
+    debugMutexFree,
+    debugMutexEnter,
+    debugMutexTry,
+    debugMutexLeave,
+
+    debugMutexHeld,
+    debugMutexNotheld
+  };
+
+  return &sMutex;
+}
+#endif /* SQLITE_DEBUG */
+
+/*
+** If compiled with SQLITE_MUTEX_NOOP, then the no-op mutex implementation
+** is used regardless of the run-time threadsafety setting.
+*/
+#ifdef SQLITE_MUTEX_NOOP
+SQLITE_PRIVATE sqlite3_mutex_methods const *sqlite3DefaultMutex(void){
+  return sqlite3NoopMutex();
+}
+#endif /* defined(SQLITE_MUTEX_NOOP) */
+#endif /* !defined(SQLITE_MUTEX_OMIT) */
+
+/************** End of mutex_noop.c ******************************************/
+/************** Begin file mutex_unix.c **************************************/
+/*
+** 2007 August 28
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C functions that implement mutexes for pthreads
+*/
+/* #include "sqliteInt.h" */
+
+/*
+** The code in this file is only used if we are compiling threadsafe
+** under unix with pthreads.
+**
+** Note that this implementation requires a version of pthreads that
+** supports recursive mutexes.
+*/
+#ifdef SQLITE_MUTEX_PTHREADS
+
+#include <pthread.h>
+
+/*
+** The sqlite3_mutex.id, sqlite3_mutex.nRef, and sqlite3_mutex.owner fields
+** are necessary under two condidtions:  (1) Debug builds and (2) using
+** home-grown mutexes.  Encapsulate these conditions into a single #define.
+*/
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HOMEGROWN_RECURSIVE_MUTEX)
+# define SQLITE_MUTEX_NREF 1
+#else
+# define SQLITE_MUTEX_NREF 0
+#endif
+
+/*
+** Each recursive mutex is an instance of the following structure.
+*/
+struct sqlite3_mutex {
+  pthread_mutex_t mutex;     /* Mutex controlling the lock */
+#if SQLITE_MUTEX_NREF || defined(SQLITE_ENABLE_API_ARMOR)
+  int id;                    /* Mutex type */
+#endif
+#if SQLITE_MUTEX_NREF
+  volatile int nRef;         /* Number of entrances */
+  volatile pthread_t owner;  /* Thread that is within this mutex */
+  int trace;                 /* True to trace changes */
+#endif
+};
+#if SQLITE_MUTEX_NREF
+#define SQLITE3_MUTEX_INITIALIZER {PTHREAD_MUTEX_INITIALIZER,0,0,(pthread_t)0,0}
+#elif defined(SQLITE_ENABLE_API_ARMOR)
+#define SQLITE3_MUTEX_INITIALIZER { PTHREAD_MUTEX_INITIALIZER, 0 }
+#else
+#define SQLITE3_MUTEX_INITIALIZER { PTHREAD_MUTEX_INITIALIZER }
+#endif
+
+/*
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
+** intended for use only inside assert() statements.  On some platforms,
+** there might be race conditions that can cause these routines to
+** deliver incorrect results.  In particular, if pthread_equal() is
+** not an atomic operation, then these routines might delivery
+** incorrect results.  On most platforms, pthread_equal() is a 
+** comparison of two integers and is therefore atomic.  But we are
+** told that HPUX is not such a platform.  If so, then these routines
+** will not always work correctly on HPUX.
+**
+** On those platforms where pthread_equal() is not atomic, SQLite
+** should be compiled without -DSQLITE_DEBUG and with -DNDEBUG to
+** make sure no assert() statements are evaluated and hence these
+** routines are never called.
+*/
+#if !defined(NDEBUG) || defined(SQLITE_DEBUG)
+static int pthreadMutexHeld(sqlite3_mutex *p){
+  return (p->nRef!=0 && pthread_equal(p->owner, pthread_self()));
+}
+static int pthreadMutexNotheld(sqlite3_mutex *p){
+  return p->nRef==0 || pthread_equal(p->owner, pthread_self())==0;
+}
+#endif
+
+/*
+** Try to provide a memory barrier operation, needed for initialization
+** and also for the implementation of xShmBarrier in the VFS in cases
+** where SQLite is compiled without mutexes.
+*/
+SQLITE_PRIVATE void sqlite3MemoryBarrier(void){
+#if defined(SQLITE_MEMORY_BARRIER)
+  SQLITE_MEMORY_BARRIER;
+#elif defined(__GNUC__) && GCC_VERSION>=4001000
+  __sync_synchronize();
+#endif
+}
+
+/*
+** Initialize and deinitialize the mutex subsystem.
+*/
+static int pthreadMutexInit(void){ return SQLITE_OK; }
+static int pthreadMutexEnd(void){ return SQLITE_OK; }
+
+/*
+** The sqlite3_mutex_alloc() routine allocates a new
+** mutex and returns a pointer to it.  If it returns NULL
+** that means that a mutex could not be allocated.  SQLite
+** will unwind its stack and return an error.  The argument
+** to sqlite3_mutex_alloc() is one of these integer constants:
+**
+** <ul>
+** <li>  SQLITE_MUTEX_FAST
+** <li>  SQLITE_MUTEX_RECURSIVE
+** <li>  SQLITE_MUTEX_STATIC_MASTER
+** <li>  SQLITE_MUTEX_STATIC_MEM
+** <li>  SQLITE_MUTEX_STATIC_OPEN
+** <li>  SQLITE_MUTEX_STATIC_PRNG
+** <li>  SQLITE_MUTEX_STATIC_LRU
+** <li>  SQLITE_MUTEX_STATIC_PMEM
+** <li>  SQLITE_MUTEX_STATIC_APP1
+** <li>  SQLITE_MUTEX_STATIC_APP2
+** <li>  SQLITE_MUTEX_STATIC_APP3
+** <li>  SQLITE_MUTEX_STATIC_VFS1
+** <li>  SQLITE_MUTEX_STATIC_VFS2
+** <li>  SQLITE_MUTEX_STATIC_VFS3
+** </ul>
+**
+** The first two constants cause sqlite3_mutex_alloc() to create
+** a new mutex.  The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
+** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
+** The mutex implementation does not need to make a distinction
+** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
+** not want to.  But SQLite will only request a recursive mutex in
+** cases where it really needs one.  If a faster non-recursive mutex
+** implementation is available on the host platform, the mutex subsystem
+** might return such a mutex in response to SQLITE_MUTEX_FAST.
+**
+** The other allowed parameters to sqlite3_mutex_alloc() each return
+** a pointer to a static preexisting mutex.  Six static mutexes are
+** used by the current version of SQLite.  Future versions of SQLite
+** may add additional static mutexes.  Static mutexes are for internal
+** use by SQLite only.  Applications that use SQLite mutexes should
+** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
+** SQLITE_MUTEX_RECURSIVE.
+**
+** Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
+** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
+** returns a different mutex on every call.  But for the static 
+** mutex types, the same mutex is returned on every call that has
+** the same type number.
+*/
+static sqlite3_mutex *pthreadMutexAlloc(int iType){
+  static sqlite3_mutex staticMutexes[] = {
+    SQLITE3_MUTEX_INITIALIZER,
+    SQLITE3_MUTEX_INITIALIZER,
+    SQLITE3_MUTEX_INITIALIZER,
+    SQLITE3_MUTEX_INITIALIZER,
+    SQLITE3_MUTEX_INITIALIZER,
+    SQLITE3_MUTEX_INITIALIZER,
+    SQLITE3_MUTEX_INITIALIZER,
+    SQLITE3_MUTEX_INITIALIZER,
+    SQLITE3_MUTEX_INITIALIZER,
+    SQLITE3_MUTEX_INITIALIZER,
+    SQLITE3_MUTEX_INITIALIZER,
+    SQLITE3_MUTEX_INITIALIZER
+  };
+  sqlite3_mutex *p;
+  switch( iType ){
+    case SQLITE_MUTEX_RECURSIVE: {
+      p = sqlite3MallocZero( sizeof(*p) );
+      if( p ){
+#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
+        /* If recursive mutexes are not available, we will have to
+        ** build our own.  See below. */
+        pthread_mutex_init(&p->mutex, 0);
+#else
+        /* Use a recursive mutex if it is available */
+        pthread_mutexattr_t recursiveAttr;
+        pthread_mutexattr_init(&recursiveAttr);
+        pthread_mutexattr_settype(&recursiveAttr, PTHREAD_MUTEX_RECURSIVE);
+        pthread_mutex_init(&p->mutex, &recursiveAttr);
+        pthread_mutexattr_destroy(&recursiveAttr);
+#endif
+      }
+      break;
+    }
+    case SQLITE_MUTEX_FAST: {
+      p = sqlite3MallocZero( sizeof(*p) );
+      if( p ){
+        pthread_mutex_init(&p->mutex, 0);
+      }
+      break;
+    }
+    default: {
+#ifdef SQLITE_ENABLE_API_ARMOR
+      if( iType-2<0 || iType-2>=ArraySize(staticMutexes) ){
+        (void)SQLITE_MISUSE_BKPT;
+        return 0;
+      }
+#endif
+      p = &staticMutexes[iType-2];
+      break;
+    }
+  }
+#if SQLITE_MUTEX_NREF || defined(SQLITE_ENABLE_API_ARMOR)
+  if( p ) p->id = iType;
+#endif
+  return p;
+}
+
+
+/*
+** This routine deallocates a previously
+** allocated mutex.  SQLite is careful to deallocate every
+** mutex that it allocates.
+*/
+static void pthreadMutexFree(sqlite3_mutex *p){
+  assert( p->nRef==0 );
+#if SQLITE_ENABLE_API_ARMOR
+  if( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE )
+#endif
+  {
+    pthread_mutex_destroy(&p->mutex);
+    sqlite3_free(p);
+  }
+#ifdef SQLITE_ENABLE_API_ARMOR
+  else{
+    (void)SQLITE_MISUSE_BKPT;
+  }
+#endif
+}
+
+/*
+** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
+** to enter a mutex.  If another thread is already within the mutex,
+** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
+** SQLITE_BUSY.  The sqlite3_mutex_try() interface returns SQLITE_OK
+** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
+** be entered multiple times by the same thread.  In such cases the,
+** mutex must be exited an equal number of times before another thread
+** can enter.  If the same thread tries to enter any other kind of mutex
+** more than once, the behavior is undefined.
+*/
+static void pthreadMutexEnter(sqlite3_mutex *p){
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || pthreadMutexNotheld(p) );
+
+#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
+  /* If recursive mutexes are not available, then we have to grow
+  ** our own.  This implementation assumes that pthread_equal()
+  ** is atomic - that it cannot be deceived into thinking self
+  ** and p->owner are equal if p->owner changes between two values
+  ** that are not equal to self while the comparison is taking place.
+  ** This implementation also assumes a coherent cache - that 
+  ** separate processes cannot read different values from the same
+  ** address at the same time.  If either of these two conditions
+  ** are not met, then the mutexes will fail and problems will result.
+  */
+  {
+    pthread_t self = pthread_self();
+    if( p->nRef>0 && pthread_equal(p->owner, self) ){
+      p->nRef++;
+    }else{
+      pthread_mutex_lock(&p->mutex);
+      assert( p->nRef==0 );
+      p->owner = self;
+      p->nRef = 1;
+    }
+  }
+#else
+  /* Use the built-in recursive mutexes if they are available.
+  */
+  pthread_mutex_lock(&p->mutex);
+#if SQLITE_MUTEX_NREF
+  assert( p->nRef>0 || p->owner==0 );
+  p->owner = pthread_self();
+  p->nRef++;
+#endif
+#endif
+
+#ifdef SQLITE_DEBUG
+  if( p->trace ){
+    printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
+  }
+#endif
+}
+static int pthreadMutexTry(sqlite3_mutex *p){
+  int rc;
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || pthreadMutexNotheld(p) );
+
+#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
+  /* If recursive mutexes are not available, then we have to grow
+  ** our own.  This implementation assumes that pthread_equal()
+  ** is atomic - that it cannot be deceived into thinking self
+  ** and p->owner are equal if p->owner changes between two values
+  ** that are not equal to self while the comparison is taking place.
+  ** This implementation also assumes a coherent cache - that 
+  ** separate processes cannot read different values from the same
+  ** address at the same time.  If either of these two conditions
+  ** are not met, then the mutexes will fail and problems will result.
+  */
+  {
+    pthread_t self = pthread_self();
+    if( p->nRef>0 && pthread_equal(p->owner, self) ){
+      p->nRef++;
+      rc = SQLITE_OK;
+    }else if( pthread_mutex_trylock(&p->mutex)==0 ){
+      assert( p->nRef==0 );
+      p->owner = self;
+      p->nRef = 1;
+      rc = SQLITE_OK;
+    }else{
+      rc = SQLITE_BUSY;
+    }
+  }
+#else
+  /* Use the built-in recursive mutexes if they are available.
+  */
+  if( pthread_mutex_trylock(&p->mutex)==0 ){
+#if SQLITE_MUTEX_NREF
+    p->owner = pthread_self();
+    p->nRef++;
+#endif
+    rc = SQLITE_OK;
+  }else{
+    rc = SQLITE_BUSY;
+  }
+#endif
+
+#ifdef SQLITE_DEBUG
+  if( rc==SQLITE_OK && p->trace ){
+    printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
+  }
+#endif
+  return rc;
+}
+
+/*
+** The sqlite3_mutex_leave() routine exits a mutex that was
+** previously entered by the same thread.  The behavior
+** is undefined if the mutex is not currently entered or
+** is not currently allocated.  SQLite will never do either.
+*/
+static void pthreadMutexLeave(sqlite3_mutex *p){
+  assert( pthreadMutexHeld(p) );
+#if SQLITE_MUTEX_NREF
+  p->nRef--;
+  if( p->nRef==0 ) p->owner = 0;
+#endif
+  assert( p->nRef==0 || p->id==SQLITE_MUTEX_RECURSIVE );
+
+#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
+  if( p->nRef==0 ){
+    pthread_mutex_unlock(&p->mutex);
+  }
+#else
+  pthread_mutex_unlock(&p->mutex);
+#endif
+
+#ifdef SQLITE_DEBUG
+  if( p->trace ){
+    printf("leave mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
+  }
+#endif
+}
+
+SQLITE_PRIVATE sqlite3_mutex_methods const *sqlite3DefaultMutex(void){
+  static const sqlite3_mutex_methods sMutex = {
+    pthreadMutexInit,
+    pthreadMutexEnd,
+    pthreadMutexAlloc,
+    pthreadMutexFree,
+    pthreadMutexEnter,
+    pthreadMutexTry,
+    pthreadMutexLeave,
+#ifdef SQLITE_DEBUG
+    pthreadMutexHeld,
+    pthreadMutexNotheld
+#else
+    0,
+    0
+#endif
+  };
+
+  return &sMutex;
+}
+
+#endif /* SQLITE_MUTEX_PTHREADS */
+
+/************** End of mutex_unix.c ******************************************/
+/************** Begin file mutex_w32.c ***************************************/
+/*
+** 2007 August 14
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C functions that implement mutexes for Win32.
+*/
+/* #include "sqliteInt.h" */
+
+#if SQLITE_OS_WIN
+/*
+** Include code that is common to all os_*.c files
+*/
+/************** Include os_common.h in the middle of mutex_w32.c *************/
+/************** Begin file os_common.h ***************************************/
+/*
+** 2004 May 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains macros and a little bit of code that is common to
+** all of the platform-specific files (os_*.c) and is #included into those
+** files.
+**
+** This file should be #included by the os_*.c files only.  It is not a
+** general purpose header file.
+*/
+#ifndef _OS_COMMON_H_
+#define _OS_COMMON_H_
+
+/*
+** At least two bugs have slipped in because we changed the MEMORY_DEBUG
+** macro to SQLITE_DEBUG and some older makefiles have not yet made the
+** switch.  The following code should catch this problem at compile-time.
+*/
+#ifdef MEMORY_DEBUG
+# error "The MEMORY_DEBUG macro is obsolete.  Use SQLITE_DEBUG instead."
+#endif
+
+/*
+** Macros for performance tracing.  Normally turned off.  Only works
+** on i486 hardware.
+*/
+#ifdef SQLITE_PERFORMANCE_TRACE
+
+/*
+** hwtime.h contains inline assembler code for implementing
+** high-performance timing routines.
+*/
+/************** Include hwtime.h in the middle of os_common.h ****************/
+/************** Begin file hwtime.h ******************************************/
+/*
+** 2008 May 27
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains inline asm code for retrieving "high-performance"
+** counters for x86 class CPUs.
+*/
+#ifndef SQLITE_HWTIME_H
+#define SQLITE_HWTIME_H
+
+/*
+** The following routine only works on pentium-class (or newer) processors.
+** It uses the RDTSC opcode to read the cycle count value out of the
+** processor and returns that value.  This can be used for high-res
+** profiling.
+*/
+#if (defined(__GNUC__) || defined(_MSC_VER)) && \
+      (defined(i386) || defined(__i386__) || defined(_M_IX86))
+
+  #if defined(__GNUC__)
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+     unsigned int lo, hi;
+     __asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
+     return (sqlite_uint64)hi << 32 | lo;
+  }
+
+  #elif defined(_MSC_VER)
+
+  __declspec(naked) __inline sqlite_uint64 __cdecl sqlite3Hwtime(void){
+     __asm {
+        rdtsc
+        ret       ; return value at EDX:EAX
+     }
+  }
+
+  #endif
+
+#elif (defined(__GNUC__) && defined(__x86_64__))
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+      unsigned long val;
+      __asm__ __volatile__ ("rdtsc" : "=A" (val));
+      return val;
+  }
+ 
+#elif (defined(__GNUC__) && defined(__ppc__))
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+      unsigned long long retval;
+      unsigned long junk;
+      __asm__ __volatile__ ("\n\
+          1:      mftbu   %1\n\
+                  mftb    %L0\n\
+                  mftbu   %0\n\
+                  cmpw    %0,%1\n\
+                  bne     1b"
+                  : "=r" (retval), "=r" (junk));
+      return retval;
+  }
+
+#else
+
+  #error Need implementation of sqlite3Hwtime() for your platform.
+
+  /*
+  ** To compile without implementing sqlite3Hwtime() for your platform,
+  ** you can remove the above #error and use the following
+  ** stub function.  You will lose timing support for many
+  ** of the debugging and testing utilities, but it should at
+  ** least compile and run.
+  */
+SQLITE_PRIVATE   sqlite_uint64 sqlite3Hwtime(void){ return ((sqlite_uint64)0); }
+
+#endif
+
+#endif /* !defined(SQLITE_HWTIME_H) */
+
+/************** End of hwtime.h **********************************************/
+/************** Continuing where we left off in os_common.h ******************/
+
+static sqlite_uint64 g_start;
+static sqlite_uint64 g_elapsed;
+#define TIMER_START       g_start=sqlite3Hwtime()
+#define TIMER_END         g_elapsed=sqlite3Hwtime()-g_start
+#define TIMER_ELAPSED     g_elapsed
+#else
+#define TIMER_START
+#define TIMER_END
+#define TIMER_ELAPSED     ((sqlite_uint64)0)
+#endif
+
+/*
+** If we compile with the SQLITE_TEST macro set, then the following block
+** of code will give us the ability to simulate a disk I/O error.  This
+** is used for testing the I/O recovery logic.
+*/
+#if defined(SQLITE_TEST)
+SQLITE_API extern int sqlite3_io_error_hit;
+SQLITE_API extern int sqlite3_io_error_hardhit;
+SQLITE_API extern int sqlite3_io_error_pending;
+SQLITE_API extern int sqlite3_io_error_persist;
+SQLITE_API extern int sqlite3_io_error_benign;
+SQLITE_API extern int sqlite3_diskfull_pending;
+SQLITE_API extern int sqlite3_diskfull;
+#define SimulateIOErrorBenign(X) sqlite3_io_error_benign=(X)
+#define SimulateIOError(CODE)  \
+  if( (sqlite3_io_error_persist && sqlite3_io_error_hit) \
+       || sqlite3_io_error_pending-- == 1 )  \
+              { local_ioerr(); CODE; }
+static void local_ioerr(){
+  IOTRACE(("IOERR\n"));
+  sqlite3_io_error_hit++;
+  if( !sqlite3_io_error_benign ) sqlite3_io_error_hardhit++;
+}
+#define SimulateDiskfullError(CODE) \
+   if( sqlite3_diskfull_pending ){ \
+     if( sqlite3_diskfull_pending == 1 ){ \
+       local_ioerr(); \
+       sqlite3_diskfull = 1; \
+       sqlite3_io_error_hit = 1; \
+       CODE; \
+     }else{ \
+       sqlite3_diskfull_pending--; \
+     } \
+   }
+#else
+#define SimulateIOErrorBenign(X)
+#define SimulateIOError(A)
+#define SimulateDiskfullError(A)
+#endif /* defined(SQLITE_TEST) */
+
+/*
+** When testing, keep a count of the number of open files.
+*/
+#if defined(SQLITE_TEST)
+SQLITE_API extern int sqlite3_open_file_count;
+#define OpenCounter(X)  sqlite3_open_file_count+=(X)
+#else
+#define OpenCounter(X)
+#endif /* defined(SQLITE_TEST) */
+
+#endif /* !defined(_OS_COMMON_H_) */
+
+/************** End of os_common.h *******************************************/
+/************** Continuing where we left off in mutex_w32.c ******************/
+
+/*
+** Include the header file for the Windows VFS.
+*/
+/************** Include os_win.h in the middle of mutex_w32.c ****************/
+/************** Begin file os_win.h ******************************************/
+/*
+** 2013 November 25
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains code that is specific to Windows.
+*/
+#ifndef SQLITE_OS_WIN_H
+#define SQLITE_OS_WIN_H
+
+/*
+** Include the primary Windows SDK header file.
+*/
+/* #include "windows.h" */
+
+#ifdef __CYGWIN__
+# include <sys/cygwin.h>
+# include <errno.h> /* amalgamator: dontcache */
+#endif
+
+/*
+** Determine if we are dealing with Windows NT.
+**
+** We ought to be able to determine if we are compiling for Windows 9x or
+** Windows NT using the _WIN32_WINNT macro as follows:
+**
+** #if defined(_WIN32_WINNT)
+** # define SQLITE_OS_WINNT 1
+** #else
+** # define SQLITE_OS_WINNT 0
+** #endif
+**
+** However, Visual Studio 2005 does not set _WIN32_WINNT by default, as
+** it ought to, so the above test does not work.  We'll just assume that
+** everything is Windows NT unless the programmer explicitly says otherwise
+** by setting SQLITE_OS_WINNT to 0.
+*/
+#if SQLITE_OS_WIN && !defined(SQLITE_OS_WINNT)
+# define SQLITE_OS_WINNT 1
+#endif
+
+/*
+** Determine if we are dealing with Windows CE - which has a much reduced
+** API.
+*/
+#if defined(_WIN32_WCE)
+# define SQLITE_OS_WINCE 1
+#else
+# define SQLITE_OS_WINCE 0
+#endif
+
+/*
+** Determine if we are dealing with WinRT, which provides only a subset of
+** the full Win32 API.
+*/
+#if !defined(SQLITE_OS_WINRT)
+# define SQLITE_OS_WINRT 0
+#endif
+
+/*
+** For WinCE, some API function parameters do not appear to be declared as
+** volatile.
+*/
+#if SQLITE_OS_WINCE
+# define SQLITE_WIN32_VOLATILE
+#else
+# define SQLITE_WIN32_VOLATILE volatile
+#endif
+
+/*
+** For some Windows sub-platforms, the _beginthreadex() / _endthreadex()
+** functions are not available (e.g. those not using MSVC, Cygwin, etc).
+*/
+#if SQLITE_OS_WIN && !SQLITE_OS_WINCE && !SQLITE_OS_WINRT && \
+    SQLITE_THREADSAFE>0 && !defined(__CYGWIN__)
+# define SQLITE_OS_WIN_THREADS 1
+#else
+# define SQLITE_OS_WIN_THREADS 0
+#endif
+
+#endif /* SQLITE_OS_WIN_H */
+
+/************** End of os_win.h **********************************************/
+/************** Continuing where we left off in mutex_w32.c ******************/
+#endif
+
+/*
+** The code in this file is only used if we are compiling multithreaded
+** on a Win32 system.
+*/
+#ifdef SQLITE_MUTEX_W32
+
+/*
+** Each recursive mutex is an instance of the following structure.
+*/
+struct sqlite3_mutex {
+  CRITICAL_SECTION mutex;    /* Mutex controlling the lock */
+  int id;                    /* Mutex type */
+#ifdef SQLITE_DEBUG
+  volatile int nRef;         /* Number of enterances */
+  volatile DWORD owner;      /* Thread holding this mutex */
+  volatile int trace;        /* True to trace changes */
+#endif
+};
+
+/*
+** These are the initializer values used when declaring a "static" mutex
+** on Win32.  It should be noted that all mutexes require initialization
+** on the Win32 platform.
+*/
+#define SQLITE_W32_MUTEX_INITIALIZER { 0 }
+
+#ifdef SQLITE_DEBUG
+#define SQLITE3_MUTEX_INITIALIZER { SQLITE_W32_MUTEX_INITIALIZER, 0, \
+                                    0L, (DWORD)0, 0 }
+#else
+#define SQLITE3_MUTEX_INITIALIZER { SQLITE_W32_MUTEX_INITIALIZER, 0 }
+#endif
+
+#ifdef SQLITE_DEBUG
+/*
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
+** intended for use only inside assert() statements.
+*/
+static int winMutexHeld(sqlite3_mutex *p){
+  return p->nRef!=0 && p->owner==GetCurrentThreadId();
+}
+
+static int winMutexNotheld2(sqlite3_mutex *p, DWORD tid){
+  return p->nRef==0 || p->owner!=tid;
+}
+
+static int winMutexNotheld(sqlite3_mutex *p){
+  DWORD tid = GetCurrentThreadId();
+  return winMutexNotheld2(p, tid);
+}
+#endif
+
+/*
+** Try to provide a memory barrier operation, needed for initialization
+** and also for the xShmBarrier method of the VFS in cases when SQLite is
+** compiled without mutexes (SQLITE_THREADSAFE=0).
+*/
+SQLITE_PRIVATE void sqlite3MemoryBarrier(void){
+#if defined(SQLITE_MEMORY_BARRIER)
+  SQLITE_MEMORY_BARRIER;
+#elif defined(__GNUC__)
+  __sync_synchronize();
+#elif !defined(SQLITE_DISABLE_INTRINSIC) && \
+      defined(_MSC_VER) && _MSC_VER>=1300
+  _ReadWriteBarrier();
+#elif defined(MemoryBarrier)
+  MemoryBarrier();
+#endif
+}
+
+/*
+** Initialize and deinitialize the mutex subsystem.
+*/
+static sqlite3_mutex winMutex_staticMutexes[] = {
+  SQLITE3_MUTEX_INITIALIZER,
+  SQLITE3_MUTEX_INITIALIZER,
+  SQLITE3_MUTEX_INITIALIZER,
+  SQLITE3_MUTEX_INITIALIZER,
+  SQLITE3_MUTEX_INITIALIZER,
+  SQLITE3_MUTEX_INITIALIZER,
+  SQLITE3_MUTEX_INITIALIZER,
+  SQLITE3_MUTEX_INITIALIZER,
+  SQLITE3_MUTEX_INITIALIZER,
+  SQLITE3_MUTEX_INITIALIZER,
+  SQLITE3_MUTEX_INITIALIZER,
+  SQLITE3_MUTEX_INITIALIZER
+};
+
+static int winMutex_isInit = 0;
+static int winMutex_isNt = -1; /* <0 means "need to query" */
+
+/* As the winMutexInit() and winMutexEnd() functions are called as part
+** of the sqlite3_initialize() and sqlite3_shutdown() processing, the
+** "interlocked" magic used here is probably not strictly necessary.
+*/
+static LONG SQLITE_WIN32_VOLATILE winMutex_lock = 0;
+
+SQLITE_API int sqlite3_win32_is_nt(void); /* os_win.c */
+SQLITE_API void sqlite3_win32_sleep(DWORD milliseconds); /* os_win.c */
+
+static int winMutexInit(void){
+  /* The first to increment to 1 does actual initialization */
+  if( InterlockedCompareExchange(&winMutex_lock, 1, 0)==0 ){
+    int i;
+    for(i=0; i<ArraySize(winMutex_staticMutexes); i++){
+#if SQLITE_OS_WINRT
+      InitializeCriticalSectionEx(&winMutex_staticMutexes[i].mutex, 0, 0);
+#else
+      InitializeCriticalSection(&winMutex_staticMutexes[i].mutex);
+#endif
+    }
+    winMutex_isInit = 1;
+  }else{
+    /* Another thread is (in the process of) initializing the static
+    ** mutexes */
+    while( !winMutex_isInit ){
+      sqlite3_win32_sleep(1);
+    }
+  }
+  return SQLITE_OK;
+}
+
+static int winMutexEnd(void){
+  /* The first to decrement to 0 does actual shutdown
+  ** (which should be the last to shutdown.) */
+  if( InterlockedCompareExchange(&winMutex_lock, 0, 1)==1 ){
+    if( winMutex_isInit==1 ){
+      int i;
+      for(i=0; i<ArraySize(winMutex_staticMutexes); i++){
+        DeleteCriticalSection(&winMutex_staticMutexes[i].mutex);
+      }
+      winMutex_isInit = 0;
+    }
+  }
+  return SQLITE_OK;
+}
+
+/*
+** The sqlite3_mutex_alloc() routine allocates a new
+** mutex and returns a pointer to it.  If it returns NULL
+** that means that a mutex could not be allocated.  SQLite
+** will unwind its stack and return an error.  The argument
+** to sqlite3_mutex_alloc() is one of these integer constants:
+**
+** <ul>
+** <li>  SQLITE_MUTEX_FAST
+** <li>  SQLITE_MUTEX_RECURSIVE
+** <li>  SQLITE_MUTEX_STATIC_MASTER
+** <li>  SQLITE_MUTEX_STATIC_MEM
+** <li>  SQLITE_MUTEX_STATIC_OPEN
+** <li>  SQLITE_MUTEX_STATIC_PRNG
+** <li>  SQLITE_MUTEX_STATIC_LRU
+** <li>  SQLITE_MUTEX_STATIC_PMEM
+** <li>  SQLITE_MUTEX_STATIC_APP1
+** <li>  SQLITE_MUTEX_STATIC_APP2
+** <li>  SQLITE_MUTEX_STATIC_APP3
+** <li>  SQLITE_MUTEX_STATIC_VFS1
+** <li>  SQLITE_MUTEX_STATIC_VFS2
+** <li>  SQLITE_MUTEX_STATIC_VFS3
+** </ul>
+**
+** The first two constants cause sqlite3_mutex_alloc() to create
+** a new mutex.  The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
+** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
+** The mutex implementation does not need to make a distinction
+** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
+** not want to.  But SQLite will only request a recursive mutex in
+** cases where it really needs one.  If a faster non-recursive mutex
+** implementation is available on the host platform, the mutex subsystem
+** might return such a mutex in response to SQLITE_MUTEX_FAST.
+**
+** The other allowed parameters to sqlite3_mutex_alloc() each return
+** a pointer to a static preexisting mutex.  Six static mutexes are
+** used by the current version of SQLite.  Future versions of SQLite
+** may add additional static mutexes.  Static mutexes are for internal
+** use by SQLite only.  Applications that use SQLite mutexes should
+** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
+** SQLITE_MUTEX_RECURSIVE.
+**
+** Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
+** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
+** returns a different mutex on every call.  But for the static
+** mutex types, the same mutex is returned on every call that has
+** the same type number.
+*/
+static sqlite3_mutex *winMutexAlloc(int iType){
+  sqlite3_mutex *p;
+
+  switch( iType ){
+    case SQLITE_MUTEX_FAST:
+    case SQLITE_MUTEX_RECURSIVE: {
+      p = sqlite3MallocZero( sizeof(*p) );
+      if( p ){
+        p->id = iType;
+#ifdef SQLITE_DEBUG
+#ifdef SQLITE_WIN32_MUTEX_TRACE_DYNAMIC
+        p->trace = 1;
+#endif
+#endif
+#if SQLITE_OS_WINRT
+        InitializeCriticalSectionEx(&p->mutex, 0, 0);
+#else
+        InitializeCriticalSection(&p->mutex);
+#endif
+      }
+      break;
+    }
+    default: {
+#ifdef SQLITE_ENABLE_API_ARMOR
+      if( iType-2<0 || iType-2>=ArraySize(winMutex_staticMutexes) ){
+        (void)SQLITE_MISUSE_BKPT;
+        return 0;
+      }
+#endif
+      p = &winMutex_staticMutexes[iType-2];
+      p->id = iType;
+#ifdef SQLITE_DEBUG
+#ifdef SQLITE_WIN32_MUTEX_TRACE_STATIC
+      p->trace = 1;
+#endif
+#endif
+      break;
+    }
+  }
+  return p;
+}
+
+
+/*
+** This routine deallocates a previously
+** allocated mutex.  SQLite is careful to deallocate every
+** mutex that it allocates.
+*/
+static void winMutexFree(sqlite3_mutex *p){
+  assert( p );
+  assert( p->nRef==0 && p->owner==0 );
+  if( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE ){
+    DeleteCriticalSection(&p->mutex);
+    sqlite3_free(p);
+  }else{
+#ifdef SQLITE_ENABLE_API_ARMOR
+    (void)SQLITE_MISUSE_BKPT;
+#endif
+  }
+}
+
+/*
+** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
+** to enter a mutex.  If another thread is already within the mutex,
+** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
+** SQLITE_BUSY.  The sqlite3_mutex_try() interface returns SQLITE_OK
+** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
+** be entered multiple times by the same thread.  In such cases the,
+** mutex must be exited an equal number of times before another thread
+** can enter.  If the same thread tries to enter any other kind of mutex
+** more than once, the behavior is undefined.
+*/
+static void winMutexEnter(sqlite3_mutex *p){
+#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
+  DWORD tid = GetCurrentThreadId();
+#endif
+#ifdef SQLITE_DEBUG
+  assert( p );
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld2(p, tid) );
+#else
+  assert( p );
+#endif
+  assert( winMutex_isInit==1 );
+  EnterCriticalSection(&p->mutex);
+#ifdef SQLITE_DEBUG
+  assert( p->nRef>0 || p->owner==0 );
+  p->owner = tid;
+  p->nRef++;
+  if( p->trace ){
+    OSTRACE(("ENTER-MUTEX tid=%lu, mutex=%p (%d), nRef=%d\n",
+             tid, p, p->trace, p->nRef));
+  }
+#endif
+}
+
+static int winMutexTry(sqlite3_mutex *p){
+#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
+  DWORD tid = GetCurrentThreadId();
+#endif
+  int rc = SQLITE_BUSY;
+  assert( p );
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld2(p, tid) );
+  /*
+  ** The sqlite3_mutex_try() routine is very rarely used, and when it
+  ** is used it is merely an optimization.  So it is OK for it to always
+  ** fail.
+  **
+  ** The TryEnterCriticalSection() interface is only available on WinNT.
+  ** And some windows compilers complain if you try to use it without
+  ** first doing some #defines that prevent SQLite from building on Win98.
+  ** For that reason, we will omit this optimization for now.  See
+  ** ticket #2685.
+  */
+#if defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x0400
+  assert( winMutex_isInit==1 );
+  assert( winMutex_isNt>=-1 && winMutex_isNt<=1 );
+  if( winMutex_isNt<0 ){
+    winMutex_isNt = sqlite3_win32_is_nt();
+  }
+  assert( winMutex_isNt==0 || winMutex_isNt==1 );
+  if( winMutex_isNt && TryEnterCriticalSection(&p->mutex) ){
+#ifdef SQLITE_DEBUG
+    p->owner = tid;
+    p->nRef++;
+#endif
+    rc = SQLITE_OK;
+  }
+#else
+  UNUSED_PARAMETER(p);
+#endif
+#ifdef SQLITE_DEBUG
+  if( p->trace ){
+    OSTRACE(("TRY-MUTEX tid=%lu, mutex=%p (%d), owner=%lu, nRef=%d, rc=%s\n",
+             tid, p, p->trace, p->owner, p->nRef, sqlite3ErrName(rc)));
+  }
+#endif
+  return rc;
+}
+
+/*
+** The sqlite3_mutex_leave() routine exits a mutex that was
+** previously entered by the same thread.  The behavior
+** is undefined if the mutex is not currently entered or
+** is not currently allocated.  SQLite will never do either.
+*/
+static void winMutexLeave(sqlite3_mutex *p){
+#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
+  DWORD tid = GetCurrentThreadId();
+#endif
+  assert( p );
+#ifdef SQLITE_DEBUG
+  assert( p->nRef>0 );
+  assert( p->owner==tid );
+  p->nRef--;
+  if( p->nRef==0 ) p->owner = 0;
+  assert( p->nRef==0 || p->id==SQLITE_MUTEX_RECURSIVE );
+#endif
+  assert( winMutex_isInit==1 );
+  LeaveCriticalSection(&p->mutex);
+#ifdef SQLITE_DEBUG
+  if( p->trace ){
+    OSTRACE(("LEAVE-MUTEX tid=%lu, mutex=%p (%d), nRef=%d\n",
+             tid, p, p->trace, p->nRef));
+  }
+#endif
+}
+
+SQLITE_PRIVATE sqlite3_mutex_methods const *sqlite3DefaultMutex(void){
+  static const sqlite3_mutex_methods sMutex = {
+    winMutexInit,
+    winMutexEnd,
+    winMutexAlloc,
+    winMutexFree,
+    winMutexEnter,
+    winMutexTry,
+    winMutexLeave,
+#ifdef SQLITE_DEBUG
+    winMutexHeld,
+    winMutexNotheld
+#else
+    0,
+    0
+#endif
+  };
+  return &sMutex;
+}
+
+#endif /* SQLITE_MUTEX_W32 */
+
+/************** End of mutex_w32.c *******************************************/
+/************** Begin file malloc.c ******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** Memory allocation functions used throughout sqlite.
+*/
+/* #include "sqliteInt.h" */
+/* #include <stdarg.h> */
+
+/*
+** Attempt to release up to n bytes of non-essential memory currently
+** held by SQLite. An example of non-essential memory is memory used to
+** cache database pages that are not currently in use.
+*/
+SQLITE_API int sqlite3_release_memory(int n){
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+  return sqlite3PcacheReleaseMemory(n);
+#else
+  /* IMPLEMENTATION-OF: R-34391-24921 The sqlite3_release_memory() routine
+  ** is a no-op returning zero if SQLite is not compiled with
+  ** SQLITE_ENABLE_MEMORY_MANAGEMENT. */
+  UNUSED_PARAMETER(n);
+  return 0;
+#endif
+}
+
+/*
+** An instance of the following object records the location of
+** each unused scratch buffer.
+*/
+typedef struct ScratchFreeslot {
+  struct ScratchFreeslot *pNext;   /* Next unused scratch buffer */
+} ScratchFreeslot;
+
+/*
+** State information local to the memory allocation subsystem.
+*/
+static SQLITE_WSD struct Mem0Global {
+  sqlite3_mutex *mutex;         /* Mutex to serialize access */
+  sqlite3_int64 alarmThreshold; /* The soft heap limit */
+
+  /*
+  ** Pointers to the end of sqlite3GlobalConfig.pScratch memory
+  ** (so that a range test can be used to determine if an allocation
+  ** being freed came from pScratch) and a pointer to the list of
+  ** unused scratch allocations.
+  */
+  void *pScratchEnd;
+  ScratchFreeslot *pScratchFree;
+  u32 nScratchFree;
+
+  /*
+  ** True if heap is nearly "full" where "full" is defined by the
+  ** sqlite3_soft_heap_limit() setting.
+  */
+  int nearlyFull;
+} mem0 = { 0, 0, 0, 0, 0, 0 };
+
+#define mem0 GLOBAL(struct Mem0Global, mem0)
+
+/*
+** Return the memory allocator mutex. sqlite3_status() needs it.
+*/
+SQLITE_PRIVATE sqlite3_mutex *sqlite3MallocMutex(void){
+  return mem0.mutex;
+}
+
+#ifndef SQLITE_OMIT_DEPRECATED
+/*
+** Deprecated external interface.  It used to set an alarm callback
+** that was invoked when memory usage grew too large.  Now it is a
+** no-op.
+*/
+SQLITE_API int sqlite3_memory_alarm(
+  void(*xCallback)(void *pArg, sqlite3_int64 used,int N),
+  void *pArg,
+  sqlite3_int64 iThreshold
+){
+  (void)xCallback;
+  (void)pArg;
+  (void)iThreshold;
+  return SQLITE_OK;
+}
+#endif
+
+/*
+** Set the soft heap-size limit for the library. Passing a zero or 
+** negative value indicates no limit.
+*/
+SQLITE_API sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 n){
+  sqlite3_int64 priorLimit;
+  sqlite3_int64 excess;
+  sqlite3_int64 nUsed;
+#ifndef SQLITE_OMIT_AUTOINIT
+  int rc = sqlite3_initialize();
+  if( rc ) return -1;
+#endif
+  sqlite3_mutex_enter(mem0.mutex);
+  priorLimit = mem0.alarmThreshold;
+  if( n<0 ){
+    sqlite3_mutex_leave(mem0.mutex);
+    return priorLimit;
+  }
+  mem0.alarmThreshold = n;
+  nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
+  mem0.nearlyFull = (n>0 && n<=nUsed);
+  sqlite3_mutex_leave(mem0.mutex);
+  excess = sqlite3_memory_used() - n;
+  if( excess>0 ) sqlite3_release_memory((int)(excess & 0x7fffffff));
+  return priorLimit;
+}
+SQLITE_API void sqlite3_soft_heap_limit(int n){
+  if( n<0 ) n = 0;
+  sqlite3_soft_heap_limit64(n);
+}
+
+/*
+** Initialize the memory allocation subsystem.
+*/
+SQLITE_PRIVATE int sqlite3MallocInit(void){
+  int rc;
+  if( sqlite3GlobalConfig.m.xMalloc==0 ){
+    sqlite3MemSetDefault();
+  }
+  memset(&mem0, 0, sizeof(mem0));
+  mem0.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
+  if( sqlite3GlobalConfig.pScratch && sqlite3GlobalConfig.szScratch>=100
+      && sqlite3GlobalConfig.nScratch>0 ){
+    int i, n, sz;
+    ScratchFreeslot *pSlot;
+    sz = ROUNDDOWN8(sqlite3GlobalConfig.szScratch);
+    sqlite3GlobalConfig.szScratch = sz;
+    pSlot = (ScratchFreeslot*)sqlite3GlobalConfig.pScratch;
+    n = sqlite3GlobalConfig.nScratch;
+    mem0.pScratchFree = pSlot;
+    mem0.nScratchFree = n;
+    for(i=0; i<n-1; i++){
+      pSlot->pNext = (ScratchFreeslot*)(sz+(char*)pSlot);
+      pSlot = pSlot->pNext;
+    }
+    pSlot->pNext = 0;
+    mem0.pScratchEnd = (void*)&pSlot[1];
+  }else{
+    mem0.pScratchEnd = 0;
+    sqlite3GlobalConfig.pScratch = 0;
+    sqlite3GlobalConfig.szScratch = 0;
+    sqlite3GlobalConfig.nScratch = 0;
+  }
+  if( sqlite3GlobalConfig.pPage==0 || sqlite3GlobalConfig.szPage<512
+      || sqlite3GlobalConfig.nPage<=0 ){
+    sqlite3GlobalConfig.pPage = 0;
+    sqlite3GlobalConfig.szPage = 0;
+  }
+  rc = sqlite3GlobalConfig.m.xInit(sqlite3GlobalConfig.m.pAppData);
+  if( rc!=SQLITE_OK ) memset(&mem0, 0, sizeof(mem0));
+  return rc;
+}
+
+/*
+** Return true if the heap is currently under memory pressure - in other
+** words if the amount of heap used is close to the limit set by
+** sqlite3_soft_heap_limit().
+*/
+SQLITE_PRIVATE int sqlite3HeapNearlyFull(void){
+  return mem0.nearlyFull;
+}
+
+/*
+** Deinitialize the memory allocation subsystem.
+*/
+SQLITE_PRIVATE void sqlite3MallocEnd(void){
+  if( sqlite3GlobalConfig.m.xShutdown ){
+    sqlite3GlobalConfig.m.xShutdown(sqlite3GlobalConfig.m.pAppData);
+  }
+  memset(&mem0, 0, sizeof(mem0));
+}
+
+/*
+** Return the amount of memory currently checked out.
+*/
+SQLITE_API sqlite3_int64 sqlite3_memory_used(void){
+  sqlite3_int64 res, mx;
+  sqlite3_status64(SQLITE_STATUS_MEMORY_USED, &res, &mx, 0);
+  return res;
+}
+
+/*
+** Return the maximum amount of memory that has ever been
+** checked out since either the beginning of this process
+** or since the most recent reset.
+*/
+SQLITE_API sqlite3_int64 sqlite3_memory_highwater(int resetFlag){
+  sqlite3_int64 res, mx;
+  sqlite3_status64(SQLITE_STATUS_MEMORY_USED, &res, &mx, resetFlag);
+  return mx;
+}
+
+/*
+** Trigger the alarm 
+*/
+static void sqlite3MallocAlarm(int nByte){
+  if( mem0.alarmThreshold<=0 ) return;
+  sqlite3_mutex_leave(mem0.mutex);
+  sqlite3_release_memory(nByte);
+  sqlite3_mutex_enter(mem0.mutex);
+}
+
+/*
+** Do a memory allocation with statistics and alarms.  Assume the
+** lock is already held.
+*/
+static int mallocWithAlarm(int n, void **pp){
+  int nFull;
+  void *p;
+  assert( sqlite3_mutex_held(mem0.mutex) );
+  nFull = sqlite3GlobalConfig.m.xRoundup(n);
+  sqlite3StatusHighwater(SQLITE_STATUS_MALLOC_SIZE, n);
+  if( mem0.alarmThreshold>0 ){
+    sqlite3_int64 nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
+    if( nUsed >= mem0.alarmThreshold - nFull ){
+      mem0.nearlyFull = 1;
+      sqlite3MallocAlarm(nFull);
+    }else{
+      mem0.nearlyFull = 0;
+    }
+  }
+  p = sqlite3GlobalConfig.m.xMalloc(nFull);
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+  if( p==0 && mem0.alarmThreshold>0 ){
+    sqlite3MallocAlarm(nFull);
+    p = sqlite3GlobalConfig.m.xMalloc(nFull);
+  }
+#endif
+  if( p ){
+    nFull = sqlite3MallocSize(p);
+    sqlite3StatusUp(SQLITE_STATUS_MEMORY_USED, nFull);
+    sqlite3StatusUp(SQLITE_STATUS_MALLOC_COUNT, 1);
+  }
+  *pp = p;
+  return nFull;
+}
+
+/*
+** Allocate memory.  This routine is like sqlite3_malloc() except that it
+** assumes the memory subsystem has already been initialized.
+*/
+SQLITE_PRIVATE void *sqlite3Malloc(u64 n){
+  void *p;
+  if( n==0 || n>=0x7fffff00 ){
+    /* A memory allocation of a number of bytes which is near the maximum
+    ** signed integer value might cause an integer overflow inside of the
+    ** xMalloc().  Hence we limit the maximum size to 0x7fffff00, giving
+    ** 255 bytes of overhead.  SQLite itself will never use anything near
+    ** this amount.  The only way to reach the limit is with sqlite3_malloc() */
+    p = 0;
+  }else if( sqlite3GlobalConfig.bMemstat ){
+    sqlite3_mutex_enter(mem0.mutex);
+    mallocWithAlarm((int)n, &p);
+    sqlite3_mutex_leave(mem0.mutex);
+  }else{
+    p = sqlite3GlobalConfig.m.xMalloc((int)n);
+  }
+  assert( EIGHT_BYTE_ALIGNMENT(p) );  /* IMP: R-11148-40995 */
+  return p;
+}
+
+/*
+** This version of the memory allocation is for use by the application.
+** First make sure the memory subsystem is initialized, then do the
+** allocation.
+*/
+SQLITE_API void *sqlite3_malloc(int n){
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  return n<=0 ? 0 : sqlite3Malloc(n);
+}
+SQLITE_API void *sqlite3_malloc64(sqlite3_uint64 n){
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  return sqlite3Malloc(n);
+}
+
+/*
+** Each thread may only have a single outstanding allocation from
+** xScratchMalloc().  We verify this constraint in the single-threaded
+** case by setting scratchAllocOut to 1 when an allocation
+** is outstanding clearing it when the allocation is freed.
+*/
+#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
+static int scratchAllocOut = 0;
+#endif
+
+
+/*
+** Allocate memory that is to be used and released right away.
+** This routine is similar to alloca() in that it is not intended
+** for situations where the memory might be held long-term.  This
+** routine is intended to get memory to old large transient data
+** structures that would not normally fit on the stack of an
+** embedded processor.
+*/
+SQLITE_PRIVATE void *sqlite3ScratchMalloc(int n){
+  void *p;
+  assert( n>0 );
+
+  sqlite3_mutex_enter(mem0.mutex);
+  sqlite3StatusHighwater(SQLITE_STATUS_SCRATCH_SIZE, n);
+  if( mem0.nScratchFree && sqlite3GlobalConfig.szScratch>=n ){
+    p = mem0.pScratchFree;
+    mem0.pScratchFree = mem0.pScratchFree->pNext;
+    mem0.nScratchFree--;
+    sqlite3StatusUp(SQLITE_STATUS_SCRATCH_USED, 1);
+    sqlite3_mutex_leave(mem0.mutex);
+  }else{
+    sqlite3_mutex_leave(mem0.mutex);
+    p = sqlite3Malloc(n);
+    if( sqlite3GlobalConfig.bMemstat && p ){
+      sqlite3_mutex_enter(mem0.mutex);
+      sqlite3StatusUp(SQLITE_STATUS_SCRATCH_OVERFLOW, sqlite3MallocSize(p));
+      sqlite3_mutex_leave(mem0.mutex);
+    }
+    sqlite3MemdebugSetType(p, MEMTYPE_SCRATCH);
+  }
+  assert( sqlite3_mutex_notheld(mem0.mutex) );
+
+
+#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
+  /* EVIDENCE-OF: R-12970-05880 SQLite will not use more than one scratch
+  ** buffers per thread.
+  **
+  ** This can only be checked in single-threaded mode.
+  */
+  assert( scratchAllocOut==0 );
+  if( p ) scratchAllocOut++;
+#endif
+
+  return p;
+}
+SQLITE_PRIVATE void sqlite3ScratchFree(void *p){
+  if( p ){
+
+#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
+    /* Verify that no more than two scratch allocation per thread
+    ** is outstanding at one time.  (This is only checked in the
+    ** single-threaded case since checking in the multi-threaded case
+    ** would be much more complicated.) */
+    assert( scratchAllocOut>=1 && scratchAllocOut<=2 );
+    scratchAllocOut--;
+#endif
+
+    if( SQLITE_WITHIN(p, sqlite3GlobalConfig.pScratch, mem0.pScratchEnd) ){
+      /* Release memory from the SQLITE_CONFIG_SCRATCH allocation */
+      ScratchFreeslot *pSlot;
+      pSlot = (ScratchFreeslot*)p;
+      sqlite3_mutex_enter(mem0.mutex);
+      pSlot->pNext = mem0.pScratchFree;
+      mem0.pScratchFree = pSlot;
+      mem0.nScratchFree++;
+      assert( mem0.nScratchFree <= (u32)sqlite3GlobalConfig.nScratch );
+      sqlite3StatusDown(SQLITE_STATUS_SCRATCH_USED, 1);
+      sqlite3_mutex_leave(mem0.mutex);
+    }else{
+      /* Release memory back to the heap */
+      assert( sqlite3MemdebugHasType(p, MEMTYPE_SCRATCH) );
+      assert( sqlite3MemdebugNoType(p, (u8)~MEMTYPE_SCRATCH) );
+      sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
+      if( sqlite3GlobalConfig.bMemstat ){
+        int iSize = sqlite3MallocSize(p);
+        sqlite3_mutex_enter(mem0.mutex);
+        sqlite3StatusDown(SQLITE_STATUS_SCRATCH_OVERFLOW, iSize);
+        sqlite3StatusDown(SQLITE_STATUS_MEMORY_USED, iSize);
+        sqlite3StatusDown(SQLITE_STATUS_MALLOC_COUNT, 1);
+        sqlite3GlobalConfig.m.xFree(p);
+        sqlite3_mutex_leave(mem0.mutex);
+      }else{
+        sqlite3GlobalConfig.m.xFree(p);
+      }
+    }
+  }
+}
+
+/*
+** TRUE if p is a lookaside memory allocation from db
+*/
+#ifndef SQLITE_OMIT_LOOKASIDE
+static int isLookaside(sqlite3 *db, void *p){
+  return SQLITE_WITHIN(p, db->lookaside.pStart, db->lookaside.pEnd);
+}
+#else
+#define isLookaside(A,B) 0
+#endif
+
+/*
+** Return the size of a memory allocation previously obtained from
+** sqlite3Malloc() or sqlite3_malloc().
+*/
+SQLITE_PRIVATE int sqlite3MallocSize(void *p){
+  assert( sqlite3MemdebugHasType(p, MEMTYPE_HEAP) );
+  return sqlite3GlobalConfig.m.xSize(p);
+}
+SQLITE_PRIVATE int sqlite3DbMallocSize(sqlite3 *db, void *p){
+  assert( p!=0 );
+  if( db==0 || !isLookaside(db,p) ){
+#if SQLITE_DEBUG
+    if( db==0 ){
+      assert( sqlite3MemdebugNoType(p, (u8)~MEMTYPE_HEAP) );
+      assert( sqlite3MemdebugHasType(p, MEMTYPE_HEAP) );
+    }else{
+      assert( sqlite3MemdebugHasType(p, (MEMTYPE_LOOKASIDE|MEMTYPE_HEAP)) );
+      assert( sqlite3MemdebugNoType(p, (u8)~(MEMTYPE_LOOKASIDE|MEMTYPE_HEAP)) );
+    }
+#endif
+    return sqlite3GlobalConfig.m.xSize(p);
+  }else{
+    assert( sqlite3_mutex_held(db->mutex) );
+    return db->lookaside.sz;
+  }
+}
+SQLITE_API sqlite3_uint64 sqlite3_msize(void *p){
+  assert( sqlite3MemdebugNoType(p, (u8)~MEMTYPE_HEAP) );
+  assert( sqlite3MemdebugHasType(p, MEMTYPE_HEAP) );
+  return p ? sqlite3GlobalConfig.m.xSize(p) : 0;
+}
+
+/*
+** Free memory previously obtained from sqlite3Malloc().
+*/
+SQLITE_API void sqlite3_free(void *p){
+  if( p==0 ) return;  /* IMP: R-49053-54554 */
+  assert( sqlite3MemdebugHasType(p, MEMTYPE_HEAP) );
+  assert( sqlite3MemdebugNoType(p, (u8)~MEMTYPE_HEAP) );
+  if( sqlite3GlobalConfig.bMemstat ){
+    sqlite3_mutex_enter(mem0.mutex);
+    sqlite3StatusDown(SQLITE_STATUS_MEMORY_USED, sqlite3MallocSize(p));
+    sqlite3StatusDown(SQLITE_STATUS_MALLOC_COUNT, 1);
+    sqlite3GlobalConfig.m.xFree(p);
+    sqlite3_mutex_leave(mem0.mutex);
+  }else{
+    sqlite3GlobalConfig.m.xFree(p);
+  }
+}
+
+/*
+** Add the size of memory allocation "p" to the count in
+** *db->pnBytesFreed.
+*/
+static SQLITE_NOINLINE void measureAllocationSize(sqlite3 *db, void *p){
+  *db->pnBytesFreed += sqlite3DbMallocSize(db,p);
+}
+
+/*
+** Free memory that might be associated with a particular database
+** connection.
+*/
+SQLITE_PRIVATE void sqlite3DbFree(sqlite3 *db, void *p){
+  assert( db==0 || sqlite3_mutex_held(db->mutex) );
+  if( p==0 ) return;
+  if( db ){
+    if( db->pnBytesFreed ){
+      measureAllocationSize(db, p);
+      return;
+    }
+    if( isLookaside(db, p) ){
+      LookasideSlot *pBuf = (LookasideSlot*)p;
+#if SQLITE_DEBUG
+      /* Trash all content in the buffer being freed */
+      memset(p, 0xaa, db->lookaside.sz);
+#endif
+      pBuf->pNext = db->lookaside.pFree;
+      db->lookaside.pFree = pBuf;
+      db->lookaside.nOut--;
+      return;
+    }
+  }
+  assert( sqlite3MemdebugHasType(p, (MEMTYPE_LOOKASIDE|MEMTYPE_HEAP)) );
+  assert( sqlite3MemdebugNoType(p, (u8)~(MEMTYPE_LOOKASIDE|MEMTYPE_HEAP)) );
+  assert( db!=0 || sqlite3MemdebugNoType(p, MEMTYPE_LOOKASIDE) );
+  sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
+  sqlite3_free(p);
+}
+
+/*
+** Change the size of an existing memory allocation
+*/
+SQLITE_PRIVATE void *sqlite3Realloc(void *pOld, u64 nBytes){
+  int nOld, nNew, nDiff;
+  void *pNew;
+  assert( sqlite3MemdebugHasType(pOld, MEMTYPE_HEAP) );
+  assert( sqlite3MemdebugNoType(pOld, (u8)~MEMTYPE_HEAP) );
+  if( pOld==0 ){
+    return sqlite3Malloc(nBytes); /* IMP: R-04300-56712 */
+  }
+  if( nBytes==0 ){
+    sqlite3_free(pOld); /* IMP: R-26507-47431 */
+    return 0;
+  }
+  if( nBytes>=0x7fffff00 ){
+    /* The 0x7ffff00 limit term is explained in comments on sqlite3Malloc() */
+    return 0;
+  }
+  nOld = sqlite3MallocSize(pOld);
+  /* IMPLEMENTATION-OF: R-46199-30249 SQLite guarantees that the second
+  ** argument to xRealloc is always a value returned by a prior call to
+  ** xRoundup. */
+  nNew = sqlite3GlobalConfig.m.xRoundup((int)nBytes);
+  if( nOld==nNew ){
+    pNew = pOld;
+  }else if( sqlite3GlobalConfig.bMemstat ){
+    sqlite3_mutex_enter(mem0.mutex);
+    sqlite3StatusHighwater(SQLITE_STATUS_MALLOC_SIZE, (int)nBytes);
+    nDiff = nNew - nOld;
+    if( sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED) >= 
+          mem0.alarmThreshold-nDiff ){
+      sqlite3MallocAlarm(nDiff);
+    }
+    pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);
+    if( pNew==0 && mem0.alarmThreshold>0 ){
+      sqlite3MallocAlarm((int)nBytes);
+      pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);
+    }
+    if( pNew ){
+      nNew = sqlite3MallocSize(pNew);
+      sqlite3StatusUp(SQLITE_STATUS_MEMORY_USED, nNew-nOld);
+    }
+    sqlite3_mutex_leave(mem0.mutex);
+  }else{
+    pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);
+  }
+  assert( EIGHT_BYTE_ALIGNMENT(pNew) ); /* IMP: R-11148-40995 */
+  return pNew;
+}
+
+/*
+** The public interface to sqlite3Realloc.  Make sure that the memory
+** subsystem is initialized prior to invoking sqliteRealloc.
+*/
+SQLITE_API void *sqlite3_realloc(void *pOld, int n){
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  if( n<0 ) n = 0;  /* IMP: R-26507-47431 */
+  return sqlite3Realloc(pOld, n);
+}
+SQLITE_API void *sqlite3_realloc64(void *pOld, sqlite3_uint64 n){
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  return sqlite3Realloc(pOld, n);
+}
+
+
+/*
+** Allocate and zero memory.
+*/ 
+SQLITE_PRIVATE void *sqlite3MallocZero(u64 n){
+  void *p = sqlite3Malloc(n);
+  if( p ){
+    memset(p, 0, (size_t)n);
+  }
+  return p;
+}
+
+/*
+** Allocate and zero memory.  If the allocation fails, make
+** the mallocFailed flag in the connection pointer.
+*/
+SQLITE_PRIVATE void *sqlite3DbMallocZero(sqlite3 *db, u64 n){
+  void *p;
+  testcase( db==0 );
+  p = sqlite3DbMallocRaw(db, n);
+  if( p ) memset(p, 0, (size_t)n);
+  return p;
+}
+
+
+/* Finish the work of sqlite3DbMallocRawNN for the unusual and
+** slower case when the allocation cannot be fulfilled using lookaside.
+*/
+static SQLITE_NOINLINE void *dbMallocRawFinish(sqlite3 *db, u64 n){
+  void *p;
+  assert( db!=0 );
+  p = sqlite3Malloc(n);
+  if( !p ) sqlite3OomFault(db);
+  sqlite3MemdebugSetType(p, 
+         (db->lookaside.bDisable==0) ? MEMTYPE_LOOKASIDE : MEMTYPE_HEAP);
+  return p;
+}
+
+/*
+** Allocate memory, either lookaside (if possible) or heap.  
+** If the allocation fails, set the mallocFailed flag in
+** the connection pointer.
+**
+** If db!=0 and db->mallocFailed is true (indicating a prior malloc
+** failure on the same database connection) then always return 0.
+** Hence for a particular database connection, once malloc starts
+** failing, it fails consistently until mallocFailed is reset.
+** This is an important assumption.  There are many places in the
+** code that do things like this:
+**
+**         int *a = (int*)sqlite3DbMallocRaw(db, 100);
+**         int *b = (int*)sqlite3DbMallocRaw(db, 200);
+**         if( b ) a[10] = 9;
+**
+** In other words, if a subsequent malloc (ex: "b") worked, it is assumed
+** that all prior mallocs (ex: "a") worked too.
+**
+** The sqlite3MallocRawNN() variant guarantees that the "db" parameter is
+** not a NULL pointer.
+*/
+SQLITE_PRIVATE void *sqlite3DbMallocRaw(sqlite3 *db, u64 n){
+  void *p;
+  if( db ) return sqlite3DbMallocRawNN(db, n);
+  p = sqlite3Malloc(n);
+  sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
+  return p;
+}
+SQLITE_PRIVATE void *sqlite3DbMallocRawNN(sqlite3 *db, u64 n){
+#ifndef SQLITE_OMIT_LOOKASIDE
+  LookasideSlot *pBuf;
+  assert( db!=0 );
+  assert( sqlite3_mutex_held(db->mutex) );
+  assert( db->pnBytesFreed==0 );
+  if( db->lookaside.bDisable==0 ){
+    assert( db->mallocFailed==0 );
+    if( n>db->lookaside.sz ){
+      db->lookaside.anStat[1]++;
+    }else if( (pBuf = db->lookaside.pFree)==0 ){
+      db->lookaside.anStat[2]++;
+    }else{
+      db->lookaside.pFree = pBuf->pNext;
+      db->lookaside.nOut++;
+      db->lookaside.anStat[0]++;
+      if( db->lookaside.nOut>db->lookaside.mxOut ){
+        db->lookaside.mxOut = db->lookaside.nOut;
+      }
+      return (void*)pBuf;
+    }
+  }else if( db->mallocFailed ){
+    return 0;
+  }
+#else
+  assert( db!=0 );
+  assert( sqlite3_mutex_held(db->mutex) );
+  assert( db->pnBytesFreed==0 );
+  if( db->mallocFailed ){
+    return 0;
+  }
+#endif
+  return dbMallocRawFinish(db, n);
+}
+
+/* Forward declaration */
+static SQLITE_NOINLINE void *dbReallocFinish(sqlite3 *db, void *p, u64 n);
+
+/*
+** Resize the block of memory pointed to by p to n bytes. If the
+** resize fails, set the mallocFailed flag in the connection object.
+*/
+SQLITE_PRIVATE void *sqlite3DbRealloc(sqlite3 *db, void *p, u64 n){
+  assert( db!=0 );
+  if( p==0 ) return sqlite3DbMallocRawNN(db, n);
+  assert( sqlite3_mutex_held(db->mutex) );
+  if( isLookaside(db,p) && n<=db->lookaside.sz ) return p;
+  return dbReallocFinish(db, p, n);
+}
+static SQLITE_NOINLINE void *dbReallocFinish(sqlite3 *db, void *p, u64 n){
+  void *pNew = 0;
+  assert( db!=0 );
+  assert( p!=0 );
+  if( db->mallocFailed==0 ){
+    if( isLookaside(db, p) ){
+      pNew = sqlite3DbMallocRawNN(db, n);
+      if( pNew ){
+        memcpy(pNew, p, db->lookaside.sz);
+        sqlite3DbFree(db, p);
+      }
+    }else{
+      assert( sqlite3MemdebugHasType(p, (MEMTYPE_LOOKASIDE|MEMTYPE_HEAP)) );
+      assert( sqlite3MemdebugNoType(p, (u8)~(MEMTYPE_LOOKASIDE|MEMTYPE_HEAP)) );
+      sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
+      pNew = sqlite3_realloc64(p, n);
+      if( !pNew ){
+        sqlite3OomFault(db);
+      }
+      sqlite3MemdebugSetType(pNew,
+            (db->lookaside.bDisable==0 ? MEMTYPE_LOOKASIDE : MEMTYPE_HEAP));
+    }
+  }
+  return pNew;
+}
+
+/*
+** Attempt to reallocate p.  If the reallocation fails, then free p
+** and set the mallocFailed flag in the database connection.
+*/
+SQLITE_PRIVATE void *sqlite3DbReallocOrFree(sqlite3 *db, void *p, u64 n){
+  void *pNew;
+  pNew = sqlite3DbRealloc(db, p, n);
+  if( !pNew ){
+    sqlite3DbFree(db, p);
+  }
+  return pNew;
+}
+
+/*
+** Make a copy of a string in memory obtained from sqliteMalloc(). These 
+** functions call sqlite3MallocRaw() directly instead of sqliteMalloc(). This
+** is because when memory debugging is turned on, these two functions are 
+** called via macros that record the current file and line number in the
+** ThreadData structure.
+*/
+SQLITE_PRIVATE char *sqlite3DbStrDup(sqlite3 *db, const char *z){
+  char *zNew;
+  size_t n;
+  if( z==0 ){
+    return 0;
+  }
+  n = sqlite3Strlen30(z) + 1;
+  assert( (n&0x7fffffff)==n );
+  zNew = sqlite3DbMallocRaw(db, (int)n);
+  if( zNew ){
+    memcpy(zNew, z, n);
+  }
+  return zNew;
+}
+SQLITE_PRIVATE char *sqlite3DbStrNDup(sqlite3 *db, const char *z, u64 n){
+  char *zNew;
+  assert( db!=0 );
+  if( z==0 ){
+    return 0;
+  }
+  assert( (n&0x7fffffff)==n );
+  zNew = sqlite3DbMallocRawNN(db, n+1);
+  if( zNew ){
+    memcpy(zNew, z, (size_t)n);
+    zNew[n] = 0;
+  }
+  return zNew;
+}
+
+/*
+** Free any prior content in *pz and replace it with a copy of zNew.
+*/
+SQLITE_PRIVATE void sqlite3SetString(char **pz, sqlite3 *db, const char *zNew){
+  sqlite3DbFree(db, *pz);
+  *pz = sqlite3DbStrDup(db, zNew);
+}
+
+/*
+** Call this routine to record the fact that an OOM (out-of-memory) error
+** has happened.  This routine will set db->mallocFailed, and also
+** temporarily disable the lookaside memory allocator and interrupt
+** any running VDBEs.
+*/
+SQLITE_PRIVATE void sqlite3OomFault(sqlite3 *db){
+  if( db->mallocFailed==0 && db->bBenignMalloc==0 ){
+    db->mallocFailed = 1;
+    if( db->nVdbeExec>0 ){
+      db->u1.isInterrupted = 1;
+    }
+    db->lookaside.bDisable++;
+  }
+}
+
+/*
+** This routine reactivates the memory allocator and clears the
+** db->mallocFailed flag as necessary.
+**
+** The memory allocator is not restarted if there are running
+** VDBEs.
+*/
+SQLITE_PRIVATE void sqlite3OomClear(sqlite3 *db){
+  if( db->mallocFailed && db->nVdbeExec==0 ){
+    db->mallocFailed = 0;
+    db->u1.isInterrupted = 0;
+    assert( db->lookaside.bDisable>0 );
+    db->lookaside.bDisable--;
+  }
+}
+
+/*
+** Take actions at the end of an API call to indicate an OOM error
+*/
+static SQLITE_NOINLINE int apiOomError(sqlite3 *db){
+  sqlite3OomClear(db);
+  sqlite3Error(db, SQLITE_NOMEM);
+  return SQLITE_NOMEM_BKPT;
+}
+
+/*
+** This function must be called before exiting any API function (i.e. 
+** returning control to the user) that has called sqlite3_malloc or
+** sqlite3_realloc.
+**
+** The returned value is normally a copy of the second argument to this
+** function. However, if a malloc() failure has occurred since the previous
+** invocation SQLITE_NOMEM is returned instead. 
+**
+** If an OOM as occurred, then the connection error-code (the value
+** returned by sqlite3_errcode()) is set to SQLITE_NOMEM.
+*/
+SQLITE_PRIVATE int sqlite3ApiExit(sqlite3* db, int rc){
+  /* If the db handle must hold the connection handle mutex here.
+  ** Otherwise the read (and possible write) of db->mallocFailed 
+  ** is unsafe, as is the call to sqlite3Error().
+  */
+  assert( db!=0 );
+  assert( sqlite3_mutex_held(db->mutex) );
+  if( db->mallocFailed || rc==SQLITE_IOERR_NOMEM ){
+    return apiOomError(db);
+  }
+  return rc & db->errMask;
+}
+
+/************** End of malloc.c **********************************************/
+/************** Begin file printf.c ******************************************/
+/*
+** The "printf" code that follows dates from the 1980's.  It is in
+** the public domain. 
+**
+**************************************************************************
+**
+** This file contains code for a set of "printf"-like routines.  These
+** routines format strings much like the printf() from the standard C
+** library, though the implementation here has enhancements to support
+** SQLite.
+*/
+/* #include "sqliteInt.h" */
+
+/*
+** Conversion types fall into various categories as defined by the
+** following enumeration.
+*/
+#define etRADIX       0 /* Integer types.  %d, %x, %o, and so forth */
+#define etFLOAT       1 /* Floating point.  %f */
+#define etEXP         2 /* Exponentional notation. %e and %E */
+#define etGENERIC     3 /* Floating or exponential, depending on exponent. %g */
+#define etSIZE        4 /* Return number of characters processed so far. %n */
+#define etSTRING      5 /* Strings. %s */
+#define etDYNSTRING   6 /* Dynamically allocated strings. %z */
+#define etPERCENT     7 /* Percent symbol. %% */
+#define etCHARX       8 /* Characters. %c */
+/* The rest are extensions, not normally found in printf() */
+#define etSQLESCAPE   9 /* Strings with '\'' doubled.  %q */
+#define etSQLESCAPE2 10 /* Strings with '\'' doubled and enclosed in '',
+                          NULL pointers replaced by SQL NULL.  %Q */
+#define etTOKEN      11 /* a pointer to a Token structure */
+#define etSRCLIST    12 /* a pointer to a SrcList */
+#define etPOINTER    13 /* The %p conversion */
+#define etSQLESCAPE3 14 /* %w -> Strings with '\"' doubled */
+#define etORDINAL    15 /* %r -> 1st, 2nd, 3rd, 4th, etc.  English only */
+
+#define etINVALID    16 /* Any unrecognized conversion type */
+
+
+/*
+** An "etByte" is an 8-bit unsigned value.
+*/
+typedef unsigned char etByte;
+
+/*
+** Each builtin conversion character (ex: the 'd' in "%d") is described
+** by an instance of the following structure
+*/
+typedef struct et_info {   /* Information about each format field */
+  char fmttype;            /* The format field code letter */
+  etByte base;             /* The base for radix conversion */
+  etByte flags;            /* One or more of FLAG_ constants below */
+  etByte type;             /* Conversion paradigm */
+  etByte charset;          /* Offset into aDigits[] of the digits string */
+  etByte prefix;           /* Offset into aPrefix[] of the prefix string */
+} et_info;
+
+/*
+** Allowed values for et_info.flags
+*/
+#define FLAG_SIGNED  1     /* True if the value to convert is signed */
+#define FLAG_INTERN  2     /* True if for internal use only */
+#define FLAG_STRING  4     /* Allow infinity precision */
+
+
+/*
+** The following table is searched linearly, so it is good to put the
+** most frequently used conversion types first.
+*/
+static const char aDigits[] = "0123456789ABCDEF0123456789abcdef";
+static const char aPrefix[] = "-x0\000X0";
+static const et_info fmtinfo[] = {
+  {  'd', 10, 1, etRADIX,      0,  0 },
+  {  's',  0, 4, etSTRING,     0,  0 },
+  {  'g',  0, 1, etGENERIC,    30, 0 },
+  {  'z',  0, 4, etDYNSTRING,  0,  0 },
+  {  'q',  0, 4, etSQLESCAPE,  0,  0 },
+  {  'Q',  0, 4, etSQLESCAPE2, 0,  0 },
+  {  'w',  0, 4, etSQLESCAPE3, 0,  0 },
+  {  'c',  0, 0, etCHARX,      0,  0 },
+  {  'o',  8, 0, etRADIX,      0,  2 },
+  {  'u', 10, 0, etRADIX,      0,  0 },
+  {  'x', 16, 0, etRADIX,      16, 1 },
+  {  'X', 16, 0, etRADIX,      0,  4 },
+#ifndef SQLITE_OMIT_FLOATING_POINT
+  {  'f',  0, 1, etFLOAT,      0,  0 },
+  {  'e',  0, 1, etEXP,        30, 0 },
+  {  'E',  0, 1, etEXP,        14, 0 },
+  {  'G',  0, 1, etGENERIC,    14, 0 },
+#endif
+  {  'i', 10, 1, etRADIX,      0,  0 },
+  {  'n',  0, 0, etSIZE,       0,  0 },
+  {  '%',  0, 0, etPERCENT,    0,  0 },
+  {  'p', 16, 0, etPOINTER,    0,  1 },
+
+/* All the rest have the FLAG_INTERN bit set and are thus for internal
+** use only */
+  {  'T',  0, 2, etTOKEN,      0,  0 },
+  {  'S',  0, 2, etSRCLIST,    0,  0 },
+  {  'r', 10, 3, etORDINAL,    0,  0 },
+};
+
+/*
+** If SQLITE_OMIT_FLOATING_POINT is defined, then none of the floating point
+** conversions will work.
+*/
+#ifndef SQLITE_OMIT_FLOATING_POINT
+/*
+** "*val" is a double such that 0.1 <= *val < 10.0
+** Return the ascii code for the leading digit of *val, then
+** multiply "*val" by 10.0 to renormalize.
+**
+** Example:
+**     input:     *val = 3.14159
+**     output:    *val = 1.4159    function return = '3'
+**
+** The counter *cnt is incremented each time.  After counter exceeds
+** 16 (the number of significant digits in a 64-bit float) '0' is
+** always returned.
+*/
+static char et_getdigit(LONGDOUBLE_TYPE *val, int *cnt){
+  int digit;
+  LONGDOUBLE_TYPE d;
+  if( (*cnt)<=0 ) return '0';
+  (*cnt)--;
+  digit = (int)*val;
+  d = digit;
+  digit += '0';
+  *val = (*val - d)*10.0;
+  return (char)digit;
+}
+#endif /* SQLITE_OMIT_FLOATING_POINT */
+
+/*
+** Set the StrAccum object to an error mode.
+*/
+static void setStrAccumError(StrAccum *p, u8 eError){
+  assert( eError==STRACCUM_NOMEM || eError==STRACCUM_TOOBIG );
+  p->accError = eError;
+  p->nAlloc = 0;
+}
+
+/*
+** Extra argument values from a PrintfArguments object
+*/
+static sqlite3_int64 getIntArg(PrintfArguments *p){
+  if( p->nArg<=p->nUsed ) return 0;
+  return sqlite3_value_int64(p->apArg[p->nUsed++]);
+}
+static double getDoubleArg(PrintfArguments *p){
+  if( p->nArg<=p->nUsed ) return 0.0;
+  return sqlite3_value_double(p->apArg[p->nUsed++]);
+}
+static char *getTextArg(PrintfArguments *p){
+  if( p->nArg<=p->nUsed ) return 0;
+  return (char*)sqlite3_value_text(p->apArg[p->nUsed++]);
+}
+
+
+/*
+** On machines with a small stack size, you can redefine the
+** SQLITE_PRINT_BUF_SIZE to be something smaller, if desired.
+*/
+#ifndef SQLITE_PRINT_BUF_SIZE
+# define SQLITE_PRINT_BUF_SIZE 70
+#endif
+#define etBUFSIZE SQLITE_PRINT_BUF_SIZE  /* Size of the output buffer */
+
+/*
+** Render a string given by "fmt" into the StrAccum object.
+*/
+SQLITE_PRIVATE void sqlite3VXPrintf(
+  StrAccum *pAccum,          /* Accumulate results here */
+  const char *fmt,           /* Format string */
+  va_list ap                 /* arguments */
+){
+  int c;                     /* Next character in the format string */
+  char *bufpt;               /* Pointer to the conversion buffer */
+  int precision;             /* Precision of the current field */
+  int length;                /* Length of the field */
+  int idx;                   /* A general purpose loop counter */
+  int width;                 /* Width of the current field */
+  etByte flag_leftjustify;   /* True if "-" flag is present */
+  etByte flag_plussign;      /* True if "+" flag is present */
+  etByte flag_blanksign;     /* True if " " flag is present */
+  etByte flag_alternateform; /* True if "#" flag is present */
+  etByte flag_altform2;      /* True if "!" flag is present */
+  etByte flag_zeropad;       /* True if field width constant starts with zero */
+  etByte flag_long;          /* True if "l" flag is present */
+  etByte flag_longlong;      /* True if the "ll" flag is present */
+  etByte done;               /* Loop termination flag */
+  etByte xtype = etINVALID;  /* Conversion paradigm */
+  u8 bArgList;               /* True for SQLITE_PRINTF_SQLFUNC */
+  u8 useIntern;              /* Ok to use internal conversions (ex: %T) */
+  char prefix;               /* Prefix character.  "+" or "-" or " " or '\0'. */
+  sqlite_uint64 longvalue;   /* Value for integer types */
+  LONGDOUBLE_TYPE realvalue; /* Value for real types */
+  const et_info *infop;      /* Pointer to the appropriate info structure */
+  char *zOut;                /* Rendering buffer */
+  int nOut;                  /* Size of the rendering buffer */
+  char *zExtra = 0;          /* Malloced memory used by some conversion */
+#ifndef SQLITE_OMIT_FLOATING_POINT
+  int  exp, e2;              /* exponent of real numbers */
+  int nsd;                   /* Number of significant digits returned */
+  double rounder;            /* Used for rounding floating point values */
+  etByte flag_dp;            /* True if decimal point should be shown */
+  etByte flag_rtz;           /* True if trailing zeros should be removed */
+#endif
+  PrintfArguments *pArgList = 0; /* Arguments for SQLITE_PRINTF_SQLFUNC */
+  char buf[etBUFSIZE];       /* Conversion buffer */
+
+  bufpt = 0;
+  if( pAccum->printfFlags ){
+    if( (bArgList = (pAccum->printfFlags & SQLITE_PRINTF_SQLFUNC))!=0 ){
+      pArgList = va_arg(ap, PrintfArguments*);
+    }
+    useIntern = pAccum->printfFlags & SQLITE_PRINTF_INTERNAL;
+  }else{
+    bArgList = useIntern = 0;
+  }
+  for(; (c=(*fmt))!=0; ++fmt){
+    if( c!='%' ){
+      bufpt = (char *)fmt;
+#if HAVE_STRCHRNUL
+      fmt = strchrnul(fmt, '%');
+#else
+      do{ fmt++; }while( *fmt && *fmt != '%' );
+#endif
+      sqlite3StrAccumAppend(pAccum, bufpt, (int)(fmt - bufpt));
+      if( *fmt==0 ) break;
+    }
+    if( (c=(*++fmt))==0 ){
+      sqlite3StrAccumAppend(pAccum, "%", 1);
+      break;
+    }
+    /* Find out what flags are present */
+    flag_leftjustify = flag_plussign = flag_blanksign = 
+     flag_alternateform = flag_altform2 = flag_zeropad = 0;
+    done = 0;
+    do{
+      switch( c ){
+        case '-':   flag_leftjustify = 1;     break;
+        case '+':   flag_plussign = 1;        break;
+        case ' ':   flag_blanksign = 1;       break;
+        case '#':   flag_alternateform = 1;   break;
+        case '!':   flag_altform2 = 1;        break;
+        case '0':   flag_zeropad = 1;         break;
+        default:    done = 1;                 break;
+      }
+    }while( !done && (c=(*++fmt))!=0 );
+    /* Get the field width */
+    if( c=='*' ){
+      if( bArgList ){
+        width = (int)getIntArg(pArgList);
+      }else{
+        width = va_arg(ap,int);
+      }
+      if( width<0 ){
+        flag_leftjustify = 1;
+        width = width >= -2147483647 ? -width : 0;
+      }
+      c = *++fmt;
+    }else{
+      unsigned wx = 0;
+      while( c>='0' && c<='9' ){
+        wx = wx*10 + c - '0';
+        c = *++fmt;
+      }
+      testcase( wx>0x7fffffff );
+      width = wx & 0x7fffffff;
+    }
+    assert( width>=0 );
+#ifdef SQLITE_PRINTF_PRECISION_LIMIT
+    if( width>SQLITE_PRINTF_PRECISION_LIMIT ){
+      width = SQLITE_PRINTF_PRECISION_LIMIT;
+    }
+#endif
+
+    /* Get the precision */
+    if( c=='.' ){
+      c = *++fmt;
+      if( c=='*' ){
+        if( bArgList ){
+          precision = (int)getIntArg(pArgList);
+        }else{
+          precision = va_arg(ap,int);
+        }
+        c = *++fmt;
+        if( precision<0 ){
+          precision = precision >= -2147483647 ? -precision : -1;
+        }
+      }else{
+        unsigned px = 0;
+        while( c>='0' && c<='9' ){
+          px = px*10 + c - '0';
+          c = *++fmt;
+        }
+        testcase( px>0x7fffffff );
+        precision = px & 0x7fffffff;
+      }
+    }else{
+      precision = -1;
+    }
+    assert( precision>=(-1) );
+#ifdef SQLITE_PRINTF_PRECISION_LIMIT
+    if( precision>SQLITE_PRINTF_PRECISION_LIMIT ){
+      precision = SQLITE_PRINTF_PRECISION_LIMIT;
+    }
+#endif
+
+
+    /* Get the conversion type modifier */
+    if( c=='l' ){
+      flag_long = 1;
+      c = *++fmt;
+      if( c=='l' ){
+        flag_longlong = 1;
+        c = *++fmt;
+      }else{
+        flag_longlong = 0;
+      }
+    }else{
+      flag_long = flag_longlong = 0;
+    }
+    /* Fetch the info entry for the field */
+    infop = &fmtinfo[0];
+    xtype = etINVALID;
+    for(idx=0; idx<ArraySize(fmtinfo); idx++){
+      if( c==fmtinfo[idx].fmttype ){
+        infop = &fmtinfo[idx];
+        if( useIntern || (infop->flags & FLAG_INTERN)==0 ){
+          xtype = infop->type;
+        }else{
+          return;
+        }
+        break;
+      }
+    }
+
+    /*
+    ** At this point, variables are initialized as follows:
+    **
+    **   flag_alternateform          TRUE if a '#' is present.
+    **   flag_altform2               TRUE if a '!' is present.
+    **   flag_plussign               TRUE if a '+' is present.
+    **   flag_leftjustify            TRUE if a '-' is present or if the
+    **                               field width was negative.
+    **   flag_zeropad                TRUE if the width began with 0.
+    **   flag_long                   TRUE if the letter 'l' (ell) prefixed
+    **                               the conversion character.
+    **   flag_longlong               TRUE if the letter 'll' (ell ell) prefixed
+    **                               the conversion character.
+    **   flag_blanksign              TRUE if a ' ' is present.
+    **   width                       The specified field width.  This is
+    **                               always non-negative.  Zero is the default.
+    **   precision                   The specified precision.  The default
+    **                               is -1.
+    **   xtype                       The class of the conversion.
+    **   infop                       Pointer to the appropriate info struct.
+    */
+    switch( xtype ){
+      case etPOINTER:
+        flag_longlong = sizeof(char*)==sizeof(i64);
+        flag_long = sizeof(char*)==sizeof(long int);
+        /* Fall through into the next case */
+      case etORDINAL:
+      case etRADIX:
+        if( infop->flags & FLAG_SIGNED ){
+          i64 v;
+          if( bArgList ){
+            v = getIntArg(pArgList);
+          }else if( flag_longlong ){
+            v = va_arg(ap,i64);
+          }else if( flag_long ){
+            v = va_arg(ap,long int);
+          }else{
+            v = va_arg(ap,int);
+          }
+          if( v<0 ){
+            if( v==SMALLEST_INT64 ){
+              longvalue = ((u64)1)<<63;
+            }else{
+              longvalue = -v;
+            }
+            prefix = '-';
+          }else{
+            longvalue = v;
+            if( flag_plussign )        prefix = '+';
+            else if( flag_blanksign )  prefix = ' ';
+            else                       prefix = 0;
+          }
+        }else{
+          if( bArgList ){
+            longvalue = (u64)getIntArg(pArgList);
+          }else if( flag_longlong ){
+            longvalue = va_arg(ap,u64);
+          }else if( flag_long ){
+            longvalue = va_arg(ap,unsigned long int);
+          }else{
+            longvalue = va_arg(ap,unsigned int);
+          }
+          prefix = 0;
+        }
+        if( longvalue==0 ) flag_alternateform = 0;
+        if( flag_zeropad && precision<width-(prefix!=0) ){
+          precision = width-(prefix!=0);
+        }
+        if( precision<etBUFSIZE-10 ){
+          nOut = etBUFSIZE;
+          zOut = buf;
+        }else{
+          nOut = precision + 10;
+          zOut = zExtra = sqlite3Malloc( nOut );
+          if( zOut==0 ){
+            setStrAccumError(pAccum, STRACCUM_NOMEM);
+            return;
+          }
+        }
+        bufpt = &zOut[nOut-1];
+        if( xtype==etORDINAL ){
+          static const char zOrd[] = "thstndrd";
+          int x = (int)(longvalue % 10);
+          if( x>=4 || (longvalue/10)%10==1 ){
+            x = 0;
+          }
+          *(--bufpt) = zOrd[x*2+1];
+          *(--bufpt) = zOrd[x*2];
+        }
+        {
+          const char *cset = &aDigits[infop->charset];
+          u8 base = infop->base;
+          do{                                           /* Convert to ascii */
+            *(--bufpt) = cset[longvalue%base];
+            longvalue = longvalue/base;
+          }while( longvalue>0 );
+        }
+        length = (int)(&zOut[nOut-1]-bufpt);
+        for(idx=precision-length; idx>0; idx--){
+          *(--bufpt) = '0';                             /* Zero pad */
+        }
+        if( prefix ) *(--bufpt) = prefix;               /* Add sign */
+        if( flag_alternateform && infop->prefix ){      /* Add "0" or "0x" */
+          const char *pre;
+          char x;
+          pre = &aPrefix[infop->prefix];
+          for(; (x=(*pre))!=0; pre++) *(--bufpt) = x;
+        }
+        length = (int)(&zOut[nOut-1]-bufpt);
+        break;
+      case etFLOAT:
+      case etEXP:
+      case etGENERIC:
+        if( bArgList ){
+          realvalue = getDoubleArg(pArgList);
+        }else{
+          realvalue = va_arg(ap,double);
+        }
+#ifdef SQLITE_OMIT_FLOATING_POINT
+        length = 0;
+#else
+        if( precision<0 ) precision = 6;         /* Set default precision */
+        if( realvalue<0.0 ){
+          realvalue = -realvalue;
+          prefix = '-';
+        }else{
+          if( flag_plussign )          prefix = '+';
+          else if( flag_blanksign )    prefix = ' ';
+          else                         prefix = 0;
+        }
+        if( xtype==etGENERIC && precision>0 ) precision--;
+        testcase( precision>0xfff );
+        for(idx=precision&0xfff, rounder=0.5; idx>0; idx--, rounder*=0.1){}
+        if( xtype==etFLOAT ) realvalue += rounder;
+        /* Normalize realvalue to within 10.0 > realvalue >= 1.0 */
+        exp = 0;
+        if( sqlite3IsNaN((double)realvalue) ){
+          bufpt = "NaN";
+          length = 3;
+          break;
+        }
+        if( realvalue>0.0 ){
+          LONGDOUBLE_TYPE scale = 1.0;
+          while( realvalue>=1e100*scale && exp<=350 ){ scale *= 1e100;exp+=100;}
+          while( realvalue>=1e10*scale && exp<=350 ){ scale *= 1e10; exp+=10; }
+          while( realvalue>=10.0*scale && exp<=350 ){ scale *= 10.0; exp++; }
+          realvalue /= scale;
+          while( realvalue<1e-8 ){ realvalue *= 1e8; exp-=8; }
+          while( realvalue<1.0 ){ realvalue *= 10.0; exp--; }
+          if( exp>350 ){
+            bufpt = buf;
+            buf[0] = prefix;
+            memcpy(buf+(prefix!=0),"Inf",4);
+            length = 3+(prefix!=0);
+            break;
+          }
+        }
+        bufpt = buf;
+        /*
+        ** If the field type is etGENERIC, then convert to either etEXP
+        ** or etFLOAT, as appropriate.
+        */
+        if( xtype!=etFLOAT ){
+          realvalue += rounder;
+          if( realvalue>=10.0 ){ realvalue *= 0.1; exp++; }
+        }
+        if( xtype==etGENERIC ){
+          flag_rtz = !flag_alternateform;
+          if( exp<-4 || exp>precision ){
+            xtype = etEXP;
+          }else{
+            precision = precision - exp;
+            xtype = etFLOAT;
+          }
+        }else{
+          flag_rtz = flag_altform2;
+        }
+        if( xtype==etEXP ){
+          e2 = 0;
+        }else{
+          e2 = exp;
+        }
+        if( MAX(e2,0)+(i64)precision+(i64)width > etBUFSIZE - 15 ){
+          bufpt = zExtra 
+              = sqlite3Malloc( MAX(e2,0)+(i64)precision+(i64)width+15 );
+          if( bufpt==0 ){
+            setStrAccumError(pAccum, STRACCUM_NOMEM);
+            return;
+          }
+        }
+        zOut = bufpt;
+        nsd = 16 + flag_altform2*10;
+        flag_dp = (precision>0 ?1:0) | flag_alternateform | flag_altform2;
+        /* The sign in front of the number */
+        if( prefix ){
+          *(bufpt++) = prefix;
+        }
+        /* Digits prior to the decimal point */
+        if( e2<0 ){
+          *(bufpt++) = '0';
+        }else{
+          for(; e2>=0; e2--){
+            *(bufpt++) = et_getdigit(&realvalue,&nsd);
+          }
+        }
+        /* The decimal point */
+        if( flag_dp ){
+          *(bufpt++) = '.';
+        }
+        /* "0" digits after the decimal point but before the first
+        ** significant digit of the number */
+        for(e2++; e2<0; precision--, e2++){
+          assert( precision>0 );
+          *(bufpt++) = '0';
+        }
+        /* Significant digits after the decimal point */
+        while( (precision--)>0 ){
+          *(bufpt++) = et_getdigit(&realvalue,&nsd);
+        }
+        /* Remove trailing zeros and the "." if no digits follow the "." */
+        if( flag_rtz && flag_dp ){
+          while( bufpt[-1]=='0' ) *(--bufpt) = 0;
+          assert( bufpt>zOut );
+          if( bufpt[-1]=='.' ){
+            if( flag_altform2 ){
+              *(bufpt++) = '0';
+            }else{
+              *(--bufpt) = 0;
+            }
+          }
+        }
+        /* Add the "eNNN" suffix */
+        if( xtype==etEXP ){
+          *(bufpt++) = aDigits[infop->charset];
+          if( exp<0 ){
+            *(bufpt++) = '-'; exp = -exp;
+          }else{
+            *(bufpt++) = '+';
+          }
+          if( exp>=100 ){
+            *(bufpt++) = (char)((exp/100)+'0');        /* 100's digit */
+            exp %= 100;
+          }
+          *(bufpt++) = (char)(exp/10+'0');             /* 10's digit */
+          *(bufpt++) = (char)(exp%10+'0');             /* 1's digit */
+        }
+        *bufpt = 0;
+
+        /* The converted number is in buf[] and zero terminated. Output it.
+        ** Note that the number is in the usual order, not reversed as with
+        ** integer conversions. */
+        length = (int)(bufpt-zOut);
+        bufpt = zOut;
+
+        /* Special case:  Add leading zeros if the flag_zeropad flag is
+        ** set and we are not left justified */
+        if( flag_zeropad && !flag_leftjustify && length < width){
+          int i;
+          int nPad = width - length;
+          for(i=width; i>=nPad; i--){
+            bufpt[i] = bufpt[i-nPad];
+          }
+          i = prefix!=0;
+          while( nPad-- ) bufpt[i++] = '0';
+          length = width;
+        }
+#endif /* !defined(SQLITE_OMIT_FLOATING_POINT) */
+        break;
+      case etSIZE:
+        if( !bArgList ){
+          *(va_arg(ap,int*)) = pAccum->nChar;
+        }
+        length = width = 0;
+        break;
+      case etPERCENT:
+        buf[0] = '%';
+        bufpt = buf;
+        length = 1;
+        break;
+      case etCHARX:
+        if( bArgList ){
+          bufpt = getTextArg(pArgList);
+          c = bufpt ? bufpt[0] : 0;
+        }else{
+          c = va_arg(ap,int);
+        }
+        if( precision>1 ){
+          width -= precision-1;
+          if( width>1 && !flag_leftjustify ){
+            sqlite3AppendChar(pAccum, width-1, ' ');
+            width = 0;
+          }
+          sqlite3AppendChar(pAccum, precision-1, c);
+        }
+        length = 1;
+        buf[0] = c;
+        bufpt = buf;
+        break;
+      case etSTRING:
+      case etDYNSTRING:
+        if( bArgList ){
+          bufpt = getTextArg(pArgList);
+          xtype = etSTRING;
+        }else{
+          bufpt = va_arg(ap,char*);
+        }
+        if( bufpt==0 ){
+          bufpt = "";
+        }else if( xtype==etDYNSTRING ){
+          zExtra = bufpt;
+        }
+        if( precision>=0 ){
+          for(length=0; length<precision && bufpt[length]; length++){}
+        }else{
+          length = sqlite3Strlen30(bufpt);
+        }
+        break;
+      case etSQLESCAPE:           /* Escape ' characters */
+      case etSQLESCAPE2:          /* Escape ' and enclose in '...' */
+      case etSQLESCAPE3: {        /* Escape " characters */
+        int i, j, k, n, isnull;
+        int needQuote;
+        char ch;
+        char q = ((xtype==etSQLESCAPE3)?'"':'\'');   /* Quote character */
+        char *escarg;
+
+        if( bArgList ){
+          escarg = getTextArg(pArgList);
+        }else{
+          escarg = va_arg(ap,char*);
+        }
+        isnull = escarg==0;
+        if( isnull ) escarg = (xtype==etSQLESCAPE2 ? "NULL" : "(NULL)");
+        k = precision;
+        for(i=n=0; k!=0 && (ch=escarg[i])!=0; i++, k--){
+          if( ch==q )  n++;
+        }
+        needQuote = !isnull && xtype==etSQLESCAPE2;
+        n += i + 3;
+        if( n>etBUFSIZE ){
+          bufpt = zExtra = sqlite3Malloc( n );
+          if( bufpt==0 ){
+            setStrAccumError(pAccum, STRACCUM_NOMEM);
+            return;
+          }
+        }else{
+          bufpt = buf;
+        }
+        j = 0;
+        if( needQuote ) bufpt[j++] = q;
+        k = i;
+        for(i=0; i<k; i++){
+          bufpt[j++] = ch = escarg[i];
+          if( ch==q ) bufpt[j++] = ch;
+        }
+        if( needQuote ) bufpt[j++] = q;
+        bufpt[j] = 0;
+        length = j;
+        /* The precision in %q and %Q means how many input characters to
+        ** consume, not the length of the output...
+        ** if( precision>=0 && precision<length ) length = precision; */
+        break;
+      }
+      case etTOKEN: {
+        Token *pToken = va_arg(ap, Token*);
+        assert( bArgList==0 );
+        if( pToken && pToken->n ){
+          sqlite3StrAccumAppend(pAccum, (const char*)pToken->z, pToken->n);
+        }
+        length = width = 0;
+        break;
+      }
+      case etSRCLIST: {
+        SrcList *pSrc = va_arg(ap, SrcList*);
+        int k = va_arg(ap, int);
+        struct SrcList_item *pItem = &pSrc->a[k];
+        assert( bArgList==0 );
+        assert( k>=0 && k<pSrc->nSrc );
+        if( pItem->zDatabase ){
+          sqlite3StrAccumAppendAll(pAccum, pItem->zDatabase);
+          sqlite3StrAccumAppend(pAccum, ".", 1);
+        }
+        sqlite3StrAccumAppendAll(pAccum, pItem->zName);
+        length = width = 0;
+        break;
+      }
+      default: {
+        assert( xtype==etINVALID );
+        return;
+      }
+    }/* End switch over the format type */
+    /*
+    ** The text of the conversion is pointed to by "bufpt" and is
+    ** "length" characters long.  The field width is "width".  Do
+    ** the output.
+    */
+    width -= length;
+    if( width>0 && !flag_leftjustify ) sqlite3AppendChar(pAccum, width, ' ');
+    sqlite3StrAccumAppend(pAccum, bufpt, length);
+    if( width>0 && flag_leftjustify ) sqlite3AppendChar(pAccum, width, ' ');
+
+    if( zExtra ){
+      sqlite3DbFree(pAccum->db, zExtra);
+      zExtra = 0;
+    }
+  }/* End for loop over the format string */
+} /* End of function */
+
+/*
+** Enlarge the memory allocation on a StrAccum object so that it is
+** able to accept at least N more bytes of text.
+**
+** Return the number of bytes of text that StrAccum is able to accept
+** after the attempted enlargement.  The value returned might be zero.
+*/
+static int sqlite3StrAccumEnlarge(StrAccum *p, int N){
+  char *zNew;
+  assert( p->nChar+(i64)N >= p->nAlloc ); /* Only called if really needed */
+  if( p->accError ){
+    testcase(p->accError==STRACCUM_TOOBIG);
+    testcase(p->accError==STRACCUM_NOMEM);
+    return 0;
+  }
+  if( p->mxAlloc==0 ){
+    N = p->nAlloc - p->nChar - 1;
+    setStrAccumError(p, STRACCUM_TOOBIG);
+    return N;
+  }else{
+    char *zOld = isMalloced(p) ? p->zText : 0;
+    i64 szNew = p->nChar;
+    assert( (p->zText==0 || p->zText==p->zBase)==!isMalloced(p) );
+    szNew += N + 1;
+    if( szNew+p->nChar<=p->mxAlloc ){
+      /* Force exponential buffer size growth as long as it does not overflow,
+      ** to avoid having to call this routine too often */
+      szNew += p->nChar;
+    }
+    if( szNew > p->mxAlloc ){
+      sqlite3StrAccumReset(p);
+      setStrAccumError(p, STRACCUM_TOOBIG);
+      return 0;
+    }else{
+      p->nAlloc = (int)szNew;
+    }
+    if( p->db ){
+      zNew = sqlite3DbRealloc(p->db, zOld, p->nAlloc);
+    }else{
+      zNew = sqlite3_realloc64(zOld, p->nAlloc);
+    }
+    if( zNew ){
+      assert( p->zText!=0 || p->nChar==0 );
+      if( !isMalloced(p) && p->nChar>0 ) memcpy(zNew, p->zText, p->nChar);
+      p->zText = zNew;
+      p->nAlloc = sqlite3DbMallocSize(p->db, zNew);
+      p->printfFlags |= SQLITE_PRINTF_MALLOCED;
+    }else{
+      sqlite3StrAccumReset(p);
+      setStrAccumError(p, STRACCUM_NOMEM);
+      return 0;
+    }
+  }
+  return N;
+}
+
+/*
+** Append N copies of character c to the given string buffer.
+*/
+SQLITE_PRIVATE void sqlite3AppendChar(StrAccum *p, int N, char c){
+  testcase( p->nChar + (i64)N > 0x7fffffff );
+  if( p->nChar+(i64)N >= p->nAlloc && (N = sqlite3StrAccumEnlarge(p, N))<=0 ){
+    return;
+  }
+  assert( (p->zText==p->zBase)==!isMalloced(p) );
+  while( (N--)>0 ) p->zText[p->nChar++] = c;
+}
+
+/*
+** The StrAccum "p" is not large enough to accept N new bytes of z[].
+** So enlarge if first, then do the append.
+**
+** This is a helper routine to sqlite3StrAccumAppend() that does special-case
+** work (enlarging the buffer) using tail recursion, so that the
+** sqlite3StrAccumAppend() routine can use fast calling semantics.
+*/
+static void SQLITE_NOINLINE enlargeAndAppend(StrAccum *p, const char *z, int N){
+  N = sqlite3StrAccumEnlarge(p, N);
+  if( N>0 ){
+    memcpy(&p->zText[p->nChar], z, N);
+    p->nChar += N;
+  }
+  assert( (p->zText==0 || p->zText==p->zBase)==!isMalloced(p) );
+}
+
+/*
+** Append N bytes of text from z to the StrAccum object.  Increase the
+** size of the memory allocation for StrAccum if necessary.
+*/
+SQLITE_PRIVATE void sqlite3StrAccumAppend(StrAccum *p, const char *z, int N){
+  assert( z!=0 || N==0 );
+  assert( p->zText!=0 || p->nChar==0 || p->accError );
+  assert( N>=0 );
+  assert( p->accError==0 || p->nAlloc==0 );
+  if( p->nChar+N >= p->nAlloc ){
+    enlargeAndAppend(p,z,N);
+  }else{
+    assert( p->zText );
+    p->nChar += N;
+    memcpy(&p->zText[p->nChar-N], z, N);
+  }
+}
+
+/*
+** Append the complete text of zero-terminated string z[] to the p string.
+*/
+SQLITE_PRIVATE void sqlite3StrAccumAppendAll(StrAccum *p, const char *z){
+  sqlite3StrAccumAppend(p, z, sqlite3Strlen30(z));
+}
+
+
+/*
+** Finish off a string by making sure it is zero-terminated.
+** Return a pointer to the resulting string.  Return a NULL
+** pointer if any kind of error was encountered.
+*/
+SQLITE_PRIVATE char *sqlite3StrAccumFinish(StrAccum *p){
+  if( p->zText ){
+    assert( (p->zText==p->zBase)==!isMalloced(p) );
+    p->zText[p->nChar] = 0;
+    if( p->mxAlloc>0 && !isMalloced(p) ){
+      p->zText = sqlite3DbMallocRaw(p->db, p->nChar+1 );
+      if( p->zText ){
+        memcpy(p->zText, p->zBase, p->nChar+1);
+        p->printfFlags |= SQLITE_PRINTF_MALLOCED;
+      }else{
+        setStrAccumError(p, STRACCUM_NOMEM);
+      }
+    }
+  }
+  return p->zText;
+}
+
+/*
+** Reset an StrAccum string.  Reclaim all malloced memory.
+*/
+SQLITE_PRIVATE void sqlite3StrAccumReset(StrAccum *p){
+  assert( (p->zText==0 || p->zText==p->zBase)==!isMalloced(p) );
+  if( isMalloced(p) ){
+    sqlite3DbFree(p->db, p->zText);
+    p->printfFlags &= ~SQLITE_PRINTF_MALLOCED;
+  }
+  p->zText = 0;
+}
+
+/*
+** Initialize a string accumulator.
+**
+** p:     The accumulator to be initialized.
+** db:    Pointer to a database connection.  May be NULL.  Lookaside
+**        memory is used if not NULL. db->mallocFailed is set appropriately
+**        when not NULL.
+** zBase: An initial buffer.  May be NULL in which case the initial buffer
+**        is malloced.
+** n:     Size of zBase in bytes.  If total space requirements never exceed
+**        n then no memory allocations ever occur.
+** mx:    Maximum number of bytes to accumulate.  If mx==0 then no memory
+**        allocations will ever occur.
+*/
+SQLITE_PRIVATE void sqlite3StrAccumInit(StrAccum *p, sqlite3 *db, char *zBase, int n, int mx){
+  p->zText = p->zBase = zBase;
+  p->db = db;
+  p->nChar = 0;
+  p->nAlloc = n;
+  p->mxAlloc = mx;
+  p->accError = 0;
+  p->printfFlags = 0;
+}
+
+/*
+** Print into memory obtained from sqliteMalloc().  Use the internal
+** %-conversion extensions.
+*/
+SQLITE_PRIVATE char *sqlite3VMPrintf(sqlite3 *db, const char *zFormat, va_list ap){
+  char *z;
+  char zBase[SQLITE_PRINT_BUF_SIZE];
+  StrAccum acc;
+  assert( db!=0 );
+  sqlite3StrAccumInit(&acc, db, zBase, sizeof(zBase),
+                      db->aLimit[SQLITE_LIMIT_LENGTH]);
+  acc.printfFlags = SQLITE_PRINTF_INTERNAL;
+  sqlite3VXPrintf(&acc, zFormat, ap);
+  z = sqlite3StrAccumFinish(&acc);
+  if( acc.accError==STRACCUM_NOMEM ){
+    sqlite3OomFault(db);
+  }
+  return z;
+}
+
+/*
+** Print into memory obtained from sqliteMalloc().  Use the internal
+** %-conversion extensions.
+*/
+SQLITE_PRIVATE char *sqlite3MPrintf(sqlite3 *db, const char *zFormat, ...){
+  va_list ap;
+  char *z;
+  va_start(ap, zFormat);
+  z = sqlite3VMPrintf(db, zFormat, ap);
+  va_end(ap);
+  return z;
+}
+
+/*
+** Print into memory obtained from sqlite3_malloc().  Omit the internal
+** %-conversion extensions.
+*/
+SQLITE_API char *sqlite3_vmprintf(const char *zFormat, va_list ap){
+  char *z;
+  char zBase[SQLITE_PRINT_BUF_SIZE];
+  StrAccum acc;
+
+#ifdef SQLITE_ENABLE_API_ARMOR  
+  if( zFormat==0 ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  sqlite3StrAccumInit(&acc, 0, zBase, sizeof(zBase), SQLITE_MAX_LENGTH);
+  sqlite3VXPrintf(&acc, zFormat, ap);
+  z = sqlite3StrAccumFinish(&acc);
+  return z;
+}
+
+/*
+** Print into memory obtained from sqlite3_malloc()().  Omit the internal
+** %-conversion extensions.
+*/
+SQLITE_API char *sqlite3_mprintf(const char *zFormat, ...){
+  va_list ap;
+  char *z;
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  va_start(ap, zFormat);
+  z = sqlite3_vmprintf(zFormat, ap);
+  va_end(ap);
+  return z;
+}
+
+/*
+** sqlite3_snprintf() works like snprintf() except that it ignores the
+** current locale settings.  This is important for SQLite because we
+** are not able to use a "," as the decimal point in place of "." as
+** specified by some locales.
+**
+** Oops:  The first two arguments of sqlite3_snprintf() are backwards
+** from the snprintf() standard.  Unfortunately, it is too late to change
+** this without breaking compatibility, so we just have to live with the
+** mistake.
+**
+** sqlite3_vsnprintf() is the varargs version.
+*/
+SQLITE_API char *sqlite3_vsnprintf(int n, char *zBuf, const char *zFormat, va_list ap){
+  StrAccum acc;
+  if( n<=0 ) return zBuf;
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( zBuf==0 || zFormat==0 ) {
+    (void)SQLITE_MISUSE_BKPT;
+    if( zBuf ) zBuf[0] = 0;
+    return zBuf;
+  }
+#endif
+  sqlite3StrAccumInit(&acc, 0, zBuf, n, 0);
+  sqlite3VXPrintf(&acc, zFormat, ap);
+  return sqlite3StrAccumFinish(&acc);
+}
+SQLITE_API char *sqlite3_snprintf(int n, char *zBuf, const char *zFormat, ...){
+  char *z;
+  va_list ap;
+  va_start(ap,zFormat);
+  z = sqlite3_vsnprintf(n, zBuf, zFormat, ap);
+  va_end(ap);
+  return z;
+}
+
+/*
+** This is the routine that actually formats the sqlite3_log() message.
+** We house it in a separate routine from sqlite3_log() to avoid using
+** stack space on small-stack systems when logging is disabled.
+**
+** sqlite3_log() must render into a static buffer.  It cannot dynamically
+** allocate memory because it might be called while the memory allocator
+** mutex is held.
+**
+** sqlite3VXPrintf() might ask for *temporary* memory allocations for
+** certain format characters (%q) or for very large precisions or widths.
+** Care must be taken that any sqlite3_log() calls that occur while the
+** memory mutex is held do not use these mechanisms.
+*/
+static void renderLogMsg(int iErrCode, const char *zFormat, va_list ap){
+  StrAccum acc;                          /* String accumulator */
+  char zMsg[SQLITE_PRINT_BUF_SIZE*3];    /* Complete log message */
+
+  sqlite3StrAccumInit(&acc, 0, zMsg, sizeof(zMsg), 0);
+  sqlite3VXPrintf(&acc, zFormat, ap);
+  sqlite3GlobalConfig.xLog(sqlite3GlobalConfig.pLogArg, iErrCode,
+                           sqlite3StrAccumFinish(&acc));
+}
+
+/*
+** Format and write a message to the log if logging is enabled.
+*/
+SQLITE_API void sqlite3_log(int iErrCode, const char *zFormat, ...){
+  va_list ap;                             /* Vararg list */
+  if( sqlite3GlobalConfig.xLog ){
+    va_start(ap, zFormat);
+    renderLogMsg(iErrCode, zFormat, ap);
+    va_end(ap);
+  }
+}
+
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
+/*
+** A version of printf() that understands %lld.  Used for debugging.
+** The printf() built into some versions of windows does not understand %lld
+** and segfaults if you give it a long long int.
+*/
+SQLITE_PRIVATE void sqlite3DebugPrintf(const char *zFormat, ...){
+  va_list ap;
+  StrAccum acc;
+  char zBuf[500];
+  sqlite3StrAccumInit(&acc, 0, zBuf, sizeof(zBuf), 0);
+  va_start(ap,zFormat);
+  sqlite3VXPrintf(&acc, zFormat, ap);
+  va_end(ap);
+  sqlite3StrAccumFinish(&acc);
+  fprintf(stdout,"%s", zBuf);
+  fflush(stdout);
+}
+#endif
+
+
+/*
+** variable-argument wrapper around sqlite3VXPrintf().  The bFlags argument
+** can contain the bit SQLITE_PRINTF_INTERNAL enable internal formats.
+*/
+SQLITE_PRIVATE void sqlite3XPrintf(StrAccum *p, const char *zFormat, ...){
+  va_list ap;
+  va_start(ap,zFormat);
+  sqlite3VXPrintf(p, zFormat, ap);
+  va_end(ap);
+}
+
+/************** End of printf.c **********************************************/
+/************** Begin file treeview.c ****************************************/
+/*
+** 2015-06-08
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains C code to implement the TreeView debugging routines.
+** These routines print a parse tree to standard output for debugging and
+** analysis. 
+**
+** The interfaces in this file is only available when compiling
+** with SQLITE_DEBUG.
+*/
+/* #include "sqliteInt.h" */
+#ifdef SQLITE_DEBUG
+
+/*
+** Add a new subitem to the tree.  The moreToFollow flag indicates that this
+** is not the last item in the tree.
+*/
+static TreeView *sqlite3TreeViewPush(TreeView *p, u8 moreToFollow){
+  if( p==0 ){
+    p = sqlite3_malloc64( sizeof(*p) );
+    if( p==0 ) return 0;
+    memset(p, 0, sizeof(*p));
+  }else{
+    p->iLevel++;
+  }
+  assert( moreToFollow==0 || moreToFollow==1 );
+  if( p->iLevel<sizeof(p->bLine) ) p->bLine[p->iLevel] = moreToFollow;
+  return p;
+}
+
+/*
+** Finished with one layer of the tree
+*/
+static void sqlite3TreeViewPop(TreeView *p){
+  if( p==0 ) return;
+  p->iLevel--;
+  if( p->iLevel<0 ) sqlite3_free(p);
+}
+
+/*
+** Generate a single line of output for the tree, with a prefix that contains
+** all the appropriate tree lines
+*/
+static void sqlite3TreeViewLine(TreeView *p, const char *zFormat, ...){
+  va_list ap;
+  int i;
+  StrAccum acc;
+  char zBuf[500];
+  sqlite3StrAccumInit(&acc, 0, zBuf, sizeof(zBuf), 0);
+  if( p ){
+    for(i=0; i<p->iLevel && i<sizeof(p->bLine)-1; i++){
+      sqlite3StrAccumAppend(&acc, p->bLine[i] ? "|   " : "    ", 4);
+    }
+    sqlite3StrAccumAppend(&acc, p->bLine[i] ? "|-- " : "'-- ", 4);
+  }
+  va_start(ap, zFormat);
+  sqlite3VXPrintf(&acc, zFormat, ap);
+  va_end(ap);
+  if( zBuf[acc.nChar-1]!='\n' ) sqlite3StrAccumAppend(&acc, "\n", 1);
+  sqlite3StrAccumFinish(&acc);
+  fprintf(stdout,"%s", zBuf);
+  fflush(stdout);
+}
+
+/*
+** Shorthand for starting a new tree item that consists of a single label
+*/
+static void sqlite3TreeViewItem(TreeView *p, const char *zLabel,u8 moreFollows){
+  p = sqlite3TreeViewPush(p, moreFollows);
+  sqlite3TreeViewLine(p, "%s", zLabel);
+}
+
+/*
+** Generate a human-readable description of a WITH clause.
+*/
+SQLITE_PRIVATE void sqlite3TreeViewWith(TreeView *pView, const With *pWith, u8 moreToFollow){
+  int i;
+  if( pWith==0 ) return;
+  if( pWith->nCte==0 ) return;
+  if( pWith->pOuter ){
+    sqlite3TreeViewLine(pView, "WITH (0x%p, pOuter=0x%p)",pWith,pWith->pOuter);
+  }else{
+    sqlite3TreeViewLine(pView, "WITH (0x%p)", pWith);
+  }
+  if( pWith->nCte>0 ){
+    pView = sqlite3TreeViewPush(pView, 1);
+    for(i=0; i<pWith->nCte; i++){
+      StrAccum x;
+      char zLine[1000];
+      const struct Cte *pCte = &pWith->a[i];
+      sqlite3StrAccumInit(&x, 0, zLine, sizeof(zLine), 0);
+      sqlite3XPrintf(&x, "%s", pCte->zName);
+      if( pCte->pCols && pCte->pCols->nExpr>0 ){
+        char cSep = '(';
+        int j;
+        for(j=0; j<pCte->pCols->nExpr; j++){
+          sqlite3XPrintf(&x, "%c%s", cSep, pCte->pCols->a[j].zName);
+          cSep = ',';
+        }
+        sqlite3XPrintf(&x, ")");
+      }
+      sqlite3XPrintf(&x, " AS");
+      sqlite3StrAccumFinish(&x);
+      sqlite3TreeViewItem(pView, zLine, i<pWith->nCte-1);
+      sqlite3TreeViewSelect(pView, pCte->pSelect, 0);
+      sqlite3TreeViewPop(pView);
+    }
+    sqlite3TreeViewPop(pView);
+  }
+}
+
+
+/*
+** Generate a human-readable description of a Select object.
+*/
+SQLITE_PRIVATE void sqlite3TreeViewSelect(TreeView *pView, const Select *p, u8 moreToFollow){
+  int n = 0;
+  int cnt = 0;
+  pView = sqlite3TreeViewPush(pView, moreToFollow);
+  if( p->pWith ){
+    sqlite3TreeViewWith(pView, p->pWith, 1);
+    cnt = 1;
+    sqlite3TreeViewPush(pView, 1);
+  }
+  do{
+    sqlite3TreeViewLine(pView, "SELECT%s%s (0x%p) selFlags=0x%x nSelectRow=%d",
+      ((p->selFlags & SF_Distinct) ? " DISTINCT" : ""),
+      ((p->selFlags & SF_Aggregate) ? " agg_flag" : ""), p, p->selFlags,
+      (int)p->nSelectRow
+    );
+    if( cnt++ ) sqlite3TreeViewPop(pView);
+    if( p->pPrior ){
+      n = 1000;
+    }else{
+      n = 0;
+      if( p->pSrc && p->pSrc->nSrc ) n++;
+      if( p->pWhere ) n++;
+      if( p->pGroupBy ) n++;
+      if( p->pHaving ) n++;
+      if( p->pOrderBy ) n++;
+      if( p->pLimit ) n++;
+      if( p->pOffset ) n++;
+    }
+    sqlite3TreeViewExprList(pView, p->pEList, (n--)>0, "result-set");
+    if( p->pSrc && p->pSrc->nSrc ){
+      int i;
+      pView = sqlite3TreeViewPush(pView, (n--)>0);
+      sqlite3TreeViewLine(pView, "FROM");
+      for(i=0; i<p->pSrc->nSrc; i++){
+        struct SrcList_item *pItem = &p->pSrc->a[i];
+        StrAccum x;
+        char zLine[100];
+        sqlite3StrAccumInit(&x, 0, zLine, sizeof(zLine), 0);
+        sqlite3XPrintf(&x, "{%d,*}", pItem->iCursor);
+        if( pItem->zDatabase ){
+          sqlite3XPrintf(&x, " %s.%s", pItem->zDatabase, pItem->zName);
+        }else if( pItem->zName ){
+          sqlite3XPrintf(&x, " %s", pItem->zName);
+        }
+        if( pItem->pTab ){
+          sqlite3XPrintf(&x, " tabname=%Q", pItem->pTab->zName);
+        }
+        if( pItem->zAlias ){
+          sqlite3XPrintf(&x, " (AS %s)", pItem->zAlias);
+        }
+        if( pItem->fg.jointype & JT_LEFT ){
+          sqlite3XPrintf(&x, " LEFT-JOIN");
+        }
+        sqlite3StrAccumFinish(&x);
+        sqlite3TreeViewItem(pView, zLine, i<p->pSrc->nSrc-1); 
+        if( pItem->pSelect ){
+          sqlite3TreeViewSelect(pView, pItem->pSelect, 0);
+        }
+        if( pItem->fg.isTabFunc ){
+          sqlite3TreeViewExprList(pView, pItem->u1.pFuncArg, 0, "func-args:");
+        }
+        sqlite3TreeViewPop(pView);
+      }
+      sqlite3TreeViewPop(pView);
+    }
+    if( p->pWhere ){
+      sqlite3TreeViewItem(pView, "WHERE", (n--)>0);
+      sqlite3TreeViewExpr(pView, p->pWhere, 0);
+      sqlite3TreeViewPop(pView);
+    }
+    if( p->pGroupBy ){
+      sqlite3TreeViewExprList(pView, p->pGroupBy, (n--)>0, "GROUPBY");
+    }
+    if( p->pHaving ){
+      sqlite3TreeViewItem(pView, "HAVING", (n--)>0);
+      sqlite3TreeViewExpr(pView, p->pHaving, 0);
+      sqlite3TreeViewPop(pView);
+    }
+    if( p->pOrderBy ){
+      sqlite3TreeViewExprList(pView, p->pOrderBy, (n--)>0, "ORDERBY");
+    }
+    if( p->pLimit ){
+      sqlite3TreeViewItem(pView, "LIMIT", (n--)>0);
+      sqlite3TreeViewExpr(pView, p->pLimit, 0);
+      sqlite3TreeViewPop(pView);
+    }
+    if( p->pOffset ){
+      sqlite3TreeViewItem(pView, "OFFSET", (n--)>0);
+      sqlite3TreeViewExpr(pView, p->pOffset, 0);
+      sqlite3TreeViewPop(pView);
+    }
+    if( p->pPrior ){
+      const char *zOp = "UNION";
+      switch( p->op ){
+        case TK_ALL:         zOp = "UNION ALL";  break;
+        case TK_INTERSECT:   zOp = "INTERSECT";  break;
+        case TK_EXCEPT:      zOp = "EXCEPT";     break;
+      }
+      sqlite3TreeViewItem(pView, zOp, 1);
+    }
+    p = p->pPrior;
+  }while( p!=0 );
+  sqlite3TreeViewPop(pView);
+}
+
+/*
+** Generate a human-readable explanation of an expression tree.
+*/
+SQLITE_PRIVATE void sqlite3TreeViewExpr(TreeView *pView, const Expr *pExpr, u8 moreToFollow){
+  const char *zBinOp = 0;   /* Binary operator */
+  const char *zUniOp = 0;   /* Unary operator */
+  char zFlgs[30];
+  pView = sqlite3TreeViewPush(pView, moreToFollow);
+  if( pExpr==0 ){
+    sqlite3TreeViewLine(pView, "nil");
+    sqlite3TreeViewPop(pView);
+    return;
+  }
+  if( pExpr->flags ){
+    sqlite3_snprintf(sizeof(zFlgs),zFlgs,"  flags=0x%x",pExpr->flags);
+  }else{
+    zFlgs[0] = 0;
+  }
+  switch( pExpr->op ){
+    case TK_AGG_COLUMN: {
+      sqlite3TreeViewLine(pView, "AGG{%d:%d}%s",
+            pExpr->iTable, pExpr->iColumn, zFlgs);
+      break;
+    }
+    case TK_COLUMN: {
+      if( pExpr->iTable<0 ){
+        /* This only happens when coding check constraints */
+        sqlite3TreeViewLine(pView, "COLUMN(%d)%s", pExpr->iColumn, zFlgs);
+      }else{
+        sqlite3TreeViewLine(pView, "{%d:%d}%s",
+                             pExpr->iTable, pExpr->iColumn, zFlgs);
+      }
+      break;
+    }
+    case TK_INTEGER: {
+      if( pExpr->flags & EP_IntValue ){
+        sqlite3TreeViewLine(pView, "%d", pExpr->u.iValue);
+      }else{
+        sqlite3TreeViewLine(pView, "%s", pExpr->u.zToken);
+      }
+      break;
+    }
+#ifndef SQLITE_OMIT_FLOATING_POINT
+    case TK_FLOAT: {
+      sqlite3TreeViewLine(pView,"%s", pExpr->u.zToken);
+      break;
+    }
+#endif
+    case TK_STRING: {
+      sqlite3TreeViewLine(pView,"%Q", pExpr->u.zToken);
+      break;
+    }
+    case TK_NULL: {
+      sqlite3TreeViewLine(pView,"NULL");
+      break;
+    }
+#ifndef SQLITE_OMIT_BLOB_LITERAL
+    case TK_BLOB: {
+      sqlite3TreeViewLine(pView,"%s", pExpr->u.zToken);
+      break;
+    }
+#endif
+    case TK_VARIABLE: {
+      sqlite3TreeViewLine(pView,"VARIABLE(%s,%d)",
+                          pExpr->u.zToken, pExpr->iColumn);
+      break;
+    }
+    case TK_REGISTER: {
+      sqlite3TreeViewLine(pView,"REGISTER(%d)", pExpr->iTable);
+      break;
+    }
+    case TK_ID: {
+      sqlite3TreeViewLine(pView,"ID \"%w\"", pExpr->u.zToken);
+      break;
+    }
+#ifndef SQLITE_OMIT_CAST
+    case TK_CAST: {
+      /* Expressions of the form:   CAST(pLeft AS token) */
+      sqlite3TreeViewLine(pView,"CAST %Q", pExpr->u.zToken);
+      sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
+      break;
+    }
+#endif /* SQLITE_OMIT_CAST */
+    case TK_LT:      zBinOp = "LT";     break;
+    case TK_LE:      zBinOp = "LE";     break;
+    case TK_GT:      zBinOp = "GT";     break;
+    case TK_GE:      zBinOp = "GE";     break;
+    case TK_NE:      zBinOp = "NE";     break;
+    case TK_EQ:      zBinOp = "EQ";     break;
+    case TK_IS:      zBinOp = "IS";     break;
+    case TK_ISNOT:   zBinOp = "ISNOT";  break;
+    case TK_AND:     zBinOp = "AND";    break;
+    case TK_OR:      zBinOp = "OR";     break;
+    case TK_PLUS:    zBinOp = "ADD";    break;
+    case TK_STAR:    zBinOp = "MUL";    break;
+    case TK_MINUS:   zBinOp = "SUB";    break;
+    case TK_REM:     zBinOp = "REM";    break;
+    case TK_BITAND:  zBinOp = "BITAND"; break;
+    case TK_BITOR:   zBinOp = "BITOR";  break;
+    case TK_SLASH:   zBinOp = "DIV";    break;
+    case TK_LSHIFT:  zBinOp = "LSHIFT"; break;
+    case TK_RSHIFT:  zBinOp = "RSHIFT"; break;
+    case TK_CONCAT:  zBinOp = "CONCAT"; break;
+    case TK_DOT:     zBinOp = "DOT";    break;
+
+    case TK_UMINUS:  zUniOp = "UMINUS"; break;
+    case TK_UPLUS:   zUniOp = "UPLUS";  break;
+    case TK_BITNOT:  zUniOp = "BITNOT"; break;
+    case TK_NOT:     zUniOp = "NOT";    break;
+    case TK_ISNULL:  zUniOp = "ISNULL"; break;
+    case TK_NOTNULL: zUniOp = "NOTNULL"; break;
+
+    case TK_SPAN: {
+      sqlite3TreeViewLine(pView, "SPAN %Q", pExpr->u.zToken);
+      sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
+      break;
+    }
+
+    case TK_COLLATE: {
+      sqlite3TreeViewLine(pView, "COLLATE %Q", pExpr->u.zToken);
+      sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
+      break;
+    }
+
+    case TK_AGG_FUNCTION:
+    case TK_FUNCTION: {
+      ExprList *pFarg;       /* List of function arguments */
+      if( ExprHasProperty(pExpr, EP_TokenOnly) ){
+        pFarg = 0;
+      }else{
+        pFarg = pExpr->x.pList;
+      }
+      if( pExpr->op==TK_AGG_FUNCTION ){
+        sqlite3TreeViewLine(pView, "AGG_FUNCTION%d %Q",
+                             pExpr->op2, pExpr->u.zToken);
+      }else{
+        sqlite3TreeViewLine(pView, "FUNCTION %Q", pExpr->u.zToken);
+      }
+      if( pFarg ){
+        sqlite3TreeViewExprList(pView, pFarg, 0, 0);
+      }
+      break;
+    }
+#ifndef SQLITE_OMIT_SUBQUERY
+    case TK_EXISTS: {
+      sqlite3TreeViewLine(pView, "EXISTS-expr");
+      sqlite3TreeViewSelect(pView, pExpr->x.pSelect, 0);
+      break;
+    }
+    case TK_SELECT: {
+      sqlite3TreeViewLine(pView, "SELECT-expr");
+      sqlite3TreeViewSelect(pView, pExpr->x.pSelect, 0);
+      break;
+    }
+    case TK_IN: {
+      sqlite3TreeViewLine(pView, "IN");
+      sqlite3TreeViewExpr(pView, pExpr->pLeft, 1);
+      if( ExprHasProperty(pExpr, EP_xIsSelect) ){
+        sqlite3TreeViewSelect(pView, pExpr->x.pSelect, 0);
+      }else{
+        sqlite3TreeViewExprList(pView, pExpr->x.pList, 0, 0);
+      }
+      break;
+    }
+#endif /* SQLITE_OMIT_SUBQUERY */
+
+    /*
+    **    x BETWEEN y AND z
+    **
+    ** This is equivalent to
+    **
+    **    x>=y AND x<=z
+    **
+    ** X is stored in pExpr->pLeft.
+    ** Y is stored in pExpr->pList->a[0].pExpr.
+    ** Z is stored in pExpr->pList->a[1].pExpr.
+    */
+    case TK_BETWEEN: {
+      Expr *pX = pExpr->pLeft;
+      Expr *pY = pExpr->x.pList->a[0].pExpr;
+      Expr *pZ = pExpr->x.pList->a[1].pExpr;
+      sqlite3TreeViewLine(pView, "BETWEEN");
+      sqlite3TreeViewExpr(pView, pX, 1);
+      sqlite3TreeViewExpr(pView, pY, 1);
+      sqlite3TreeViewExpr(pView, pZ, 0);
+      break;
+    }
+    case TK_TRIGGER: {
+      /* If the opcode is TK_TRIGGER, then the expression is a reference
+      ** to a column in the new.* or old.* pseudo-tables available to
+      ** trigger programs. In this case Expr.iTable is set to 1 for the
+      ** new.* pseudo-table, or 0 for the old.* pseudo-table. Expr.iColumn
+      ** is set to the column of the pseudo-table to read, or to -1 to
+      ** read the rowid field.
+      */
+      sqlite3TreeViewLine(pView, "%s(%d)", 
+          pExpr->iTable ? "NEW" : "OLD", pExpr->iColumn);
+      break;
+    }
+    case TK_CASE: {
+      sqlite3TreeViewLine(pView, "CASE");
+      sqlite3TreeViewExpr(pView, pExpr->pLeft, 1);
+      sqlite3TreeViewExprList(pView, pExpr->x.pList, 0, 0);
+      break;
+    }
+#ifndef SQLITE_OMIT_TRIGGER
+    case TK_RAISE: {
+      const char *zType = "unk";
+      switch( pExpr->affinity ){
+        case OE_Rollback:   zType = "rollback";  break;
+        case OE_Abort:      zType = "abort";     break;
+        case OE_Fail:       zType = "fail";      break;
+        case OE_Ignore:     zType = "ignore";    break;
+      }
+      sqlite3TreeViewLine(pView, "RAISE %s(%Q)", zType, pExpr->u.zToken);
+      break;
+    }
+#endif
+    case TK_MATCH: {
+      sqlite3TreeViewLine(pView, "MATCH {%d:%d}%s",
+                          pExpr->iTable, pExpr->iColumn, zFlgs);
+      sqlite3TreeViewExpr(pView, pExpr->pRight, 0);
+      break;
+    }
+    case TK_VECTOR: {
+      sqlite3TreeViewBareExprList(pView, pExpr->x.pList, "VECTOR");
+      break;
+    }
+    case TK_SELECT_COLUMN: {
+      sqlite3TreeViewLine(pView, "SELECT-COLUMN %d", pExpr->iColumn);
+      sqlite3TreeViewSelect(pView, pExpr->pLeft->x.pSelect, 0);
+      break;
+    }
+    default: {
+      sqlite3TreeViewLine(pView, "op=%d", pExpr->op);
+      break;
+    }
+  }
+  if( zBinOp ){
+    sqlite3TreeViewLine(pView, "%s%s", zBinOp, zFlgs);
+    sqlite3TreeViewExpr(pView, pExpr->pLeft, 1);
+    sqlite3TreeViewExpr(pView, pExpr->pRight, 0);
+  }else if( zUniOp ){
+    sqlite3TreeViewLine(pView, "%s%s", zUniOp, zFlgs);
+    sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
+  }
+  sqlite3TreeViewPop(pView);
+}
+
+
+/*
+** Generate a human-readable explanation of an expression list.
+*/
+SQLITE_PRIVATE void sqlite3TreeViewBareExprList(
+  TreeView *pView,
+  const ExprList *pList,
+  const char *zLabel
+){
+  if( zLabel==0 || zLabel[0]==0 ) zLabel = "LIST";
+  if( pList==0 ){
+    sqlite3TreeViewLine(pView, "%s (empty)", zLabel);
+  }else{
+    int i;
+    sqlite3TreeViewLine(pView, "%s", zLabel);
+    for(i=0; i<pList->nExpr; i++){
+      int j = pList->a[i].u.x.iOrderByCol;
+      if( j ){
+        sqlite3TreeViewPush(pView, 0);
+        sqlite3TreeViewLine(pView, "iOrderByCol=%d", j);
+      }
+      sqlite3TreeViewExpr(pView, pList->a[i].pExpr, i<pList->nExpr-1);
+      if( j ) sqlite3TreeViewPop(pView);
+    }
+  }
+}
+SQLITE_PRIVATE void sqlite3TreeViewExprList(
+  TreeView *pView,
+  const ExprList *pList,
+  u8 moreToFollow,
+  const char *zLabel
+){
+  pView = sqlite3TreeViewPush(pView, moreToFollow);
+  sqlite3TreeViewBareExprList(pView, pList, zLabel);
+  sqlite3TreeViewPop(pView);
+}
+
+#endif /* SQLITE_DEBUG */
+
+/************** End of treeview.c ********************************************/
+/************** Begin file random.c ******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains code to implement a pseudo-random number
+** generator (PRNG) for SQLite.
+**
+** Random numbers are used by some of the database backends in order
+** to generate random integer keys for tables or random filenames.
+*/
+/* #include "sqliteInt.h" */
+
+
+/* All threads share a single random number generator.
+** This structure is the current state of the generator.
+*/
+static SQLITE_WSD struct sqlite3PrngType {
+  unsigned char isInit;          /* True if initialized */
+  unsigned char i, j;            /* State variables */
+  unsigned char s[256];          /* State variables */
+} sqlite3Prng;
+
+/*
+** Return N random bytes.
+*/
+SQLITE_API void sqlite3_randomness(int N, void *pBuf){
+  unsigned char t;
+  unsigned char *zBuf = pBuf;
+
+  /* The "wsdPrng" macro will resolve to the pseudo-random number generator
+  ** state vector.  If writable static data is unsupported on the target,
+  ** we have to locate the state vector at run-time.  In the more common
+  ** case where writable static data is supported, wsdPrng can refer directly
+  ** to the "sqlite3Prng" state vector declared above.
+  */
+#ifdef SQLITE_OMIT_WSD
+  struct sqlite3PrngType *p = &GLOBAL(struct sqlite3PrngType, sqlite3Prng);
+# define wsdPrng p[0]
+#else
+# define wsdPrng sqlite3Prng
+#endif
+
+#if SQLITE_THREADSAFE
+  sqlite3_mutex *mutex;
+#endif
+
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return;
+#endif
+
+#if SQLITE_THREADSAFE
+  mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_PRNG);
+#endif
+
+  sqlite3_mutex_enter(mutex);
+  if( N<=0 || pBuf==0 ){
+    wsdPrng.isInit = 0;
+    sqlite3_mutex_leave(mutex);
+    return;
+  }
+
+  /* Initialize the state of the random number generator once,
+  ** the first time this routine is called.  The seed value does
+  ** not need to contain a lot of randomness since we are not
+  ** trying to do secure encryption or anything like that...
+  **
+  ** Nothing in this file or anywhere else in SQLite does any kind of
+  ** encryption.  The RC4 algorithm is being used as a PRNG (pseudo-random
+  ** number generator) not as an encryption device.
+  */
+  if( !wsdPrng.isInit ){
+    int i;
+    char k[256];
+    wsdPrng.j = 0;
+    wsdPrng.i = 0;
+    sqlite3OsRandomness(sqlite3_vfs_find(0), 256, k);
+    for(i=0; i<256; i++){
+      wsdPrng.s[i] = (u8)i;
+    }
+    for(i=0; i<256; i++){
+      wsdPrng.j += wsdPrng.s[i] + k[i];
+      t = wsdPrng.s[wsdPrng.j];
+      wsdPrng.s[wsdPrng.j] = wsdPrng.s[i];
+      wsdPrng.s[i] = t;
+    }
+    wsdPrng.isInit = 1;
+  }
+
+  assert( N>0 );
+  do{
+    wsdPrng.i++;
+    t = wsdPrng.s[wsdPrng.i];
+    wsdPrng.j += t;
+    wsdPrng.s[wsdPrng.i] = wsdPrng.s[wsdPrng.j];
+    wsdPrng.s[wsdPrng.j] = t;
+    t += wsdPrng.s[wsdPrng.i];
+    *(zBuf++) = wsdPrng.s[t];
+  }while( --N );
+  sqlite3_mutex_leave(mutex);
+}
+
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+/*
+** For testing purposes, we sometimes want to preserve the state of
+** PRNG and restore the PRNG to its saved state at a later time, or
+** to reset the PRNG to its initial state.  These routines accomplish
+** those tasks.
+**
+** The sqlite3_test_control() interface calls these routines to
+** control the PRNG.
+*/
+static SQLITE_WSD struct sqlite3PrngType sqlite3SavedPrng;
+SQLITE_PRIVATE void sqlite3PrngSaveState(void){
+  memcpy(
+    &GLOBAL(struct sqlite3PrngType, sqlite3SavedPrng),
+    &GLOBAL(struct sqlite3PrngType, sqlite3Prng),
+    sizeof(sqlite3Prng)
+  );
+}
+SQLITE_PRIVATE void sqlite3PrngRestoreState(void){
+  memcpy(
+    &GLOBAL(struct sqlite3PrngType, sqlite3Prng),
+    &GLOBAL(struct sqlite3PrngType, sqlite3SavedPrng),
+    sizeof(sqlite3Prng)
+  );
+}
+#endif /* SQLITE_OMIT_BUILTIN_TEST */
+
+/************** End of random.c **********************************************/
+/************** Begin file threads.c *****************************************/
+/*
+** 2012 July 21
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file presents a simple cross-platform threading interface for
+** use internally by SQLite.
+**
+** A "thread" can be created using sqlite3ThreadCreate().  This thread
+** runs independently of its creator until it is joined using
+** sqlite3ThreadJoin(), at which point it terminates.
+**
+** Threads do not have to be real.  It could be that the work of the
+** "thread" is done by the main thread at either the sqlite3ThreadCreate()
+** or sqlite3ThreadJoin() call.  This is, in fact, what happens in
+** single threaded systems.  Nothing in SQLite requires multiple threads.
+** This interface exists so that applications that want to take advantage
+** of multiple cores can do so, while also allowing applications to stay
+** single-threaded if desired.
+*/
+/* #include "sqliteInt.h" */
+#if SQLITE_OS_WIN
+/* #  include "os_win.h" */
+#endif
+
+#if SQLITE_MAX_WORKER_THREADS>0
+
+/********************************* Unix Pthreads ****************************/
+#if SQLITE_OS_UNIX && defined(SQLITE_MUTEX_PTHREADS) && SQLITE_THREADSAFE>0
+
+#define SQLITE_THREADS_IMPLEMENTED 1  /* Prevent the single-thread code below */
+/* #include <pthread.h> */
+
+/* A running thread */
+struct SQLiteThread {
+  pthread_t tid;                 /* Thread ID */
+  int done;                      /* Set to true when thread finishes */
+  void *pOut;                    /* Result returned by the thread */
+  void *(*xTask)(void*);         /* The thread routine */
+  void *pIn;                     /* Argument to the thread */
+};
+
+/* Create a new thread */
+SQLITE_PRIVATE int sqlite3ThreadCreate(
+  SQLiteThread **ppThread,  /* OUT: Write the thread object here */
+  void *(*xTask)(void*),    /* Routine to run in a separate thread */
+  void *pIn                 /* Argument passed into xTask() */
+){
+  SQLiteThread *p;
+  int rc;
+
+  assert( ppThread!=0 );
+  assert( xTask!=0 );
+  /* This routine is never used in single-threaded mode */
+  assert( sqlite3GlobalConfig.bCoreMutex!=0 );
+
+  *ppThread = 0;
+  p = sqlite3Malloc(sizeof(*p));
+  if( p==0 ) return SQLITE_NOMEM_BKPT;
+  memset(p, 0, sizeof(*p));
+  p->xTask = xTask;
+  p->pIn = pIn;
+  /* If the SQLITE_TESTCTRL_FAULT_INSTALL callback is registered to a 
+  ** function that returns SQLITE_ERROR when passed the argument 200, that
+  ** forces worker threads to run sequentially and deterministically 
+  ** for testing purposes. */
+  if( sqlite3FaultSim(200) ){
+    rc = 1;
+  }else{    
+    rc = pthread_create(&p->tid, 0, xTask, pIn);
+  }
+  if( rc ){
+    p->done = 1;
+    p->pOut = xTask(pIn);
+  }
+  *ppThread = p;
+  return SQLITE_OK;
+}
+
+/* Get the results of the thread */
+SQLITE_PRIVATE int sqlite3ThreadJoin(SQLiteThread *p, void **ppOut){
+  int rc;
+
+  assert( ppOut!=0 );
+  if( NEVER(p==0) ) return SQLITE_NOMEM_BKPT;
+  if( p->done ){
+    *ppOut = p->pOut;
+    rc = SQLITE_OK;
+  }else{
+    rc = pthread_join(p->tid, ppOut) ? SQLITE_ERROR : SQLITE_OK;
+  }
+  sqlite3_free(p);
+  return rc;
+}
+
+#endif /* SQLITE_OS_UNIX && defined(SQLITE_MUTEX_PTHREADS) */
+/******************************** End Unix Pthreads *************************/
+
+
+/********************************* Win32 Threads ****************************/
+#if SQLITE_OS_WIN_THREADS
+
+#define SQLITE_THREADS_IMPLEMENTED 1  /* Prevent the single-thread code below */
+#include <process.h>
+
+/* A running thread */
+struct SQLiteThread {
+  void *tid;               /* The thread handle */
+  unsigned id;             /* The thread identifier */
+  void *(*xTask)(void*);   /* The routine to run as a thread */
+  void *pIn;               /* Argument to xTask */
+  void *pResult;           /* Result of xTask */
+};
+
+/* Thread procedure Win32 compatibility shim */
+static unsigned __stdcall sqlite3ThreadProc(
+  void *pArg  /* IN: Pointer to the SQLiteThread structure */
+){
+  SQLiteThread *p = (SQLiteThread *)pArg;
+
+  assert( p!=0 );
+#if 0
+  /*
+  ** This assert appears to trigger spuriously on certain
+  ** versions of Windows, possibly due to _beginthreadex()
+  ** and/or CreateThread() not fully setting their thread
+  ** ID parameter before starting the thread.
+  */
+  assert( p->id==GetCurrentThreadId() );
+#endif
+  assert( p->xTask!=0 );
+  p->pResult = p->xTask(p->pIn);
+
+  _endthreadex(0);
+  return 0; /* NOT REACHED */
+}
+
+/* Create a new thread */
+SQLITE_PRIVATE int sqlite3ThreadCreate(
+  SQLiteThread **ppThread,  /* OUT: Write the thread object here */
+  void *(*xTask)(void*),    /* Routine to run in a separate thread */
+  void *pIn                 /* Argument passed into xTask() */
+){
+  SQLiteThread *p;
+
+  assert( ppThread!=0 );
+  assert( xTask!=0 );
+  *ppThread = 0;
+  p = sqlite3Malloc(sizeof(*p));
+  if( p==0 ) return SQLITE_NOMEM_BKPT;
+  /* If the SQLITE_TESTCTRL_FAULT_INSTALL callback is registered to a 
+  ** function that returns SQLITE_ERROR when passed the argument 200, that
+  ** forces worker threads to run sequentially and deterministically 
+  ** (via the sqlite3FaultSim() term of the conditional) for testing
+  ** purposes. */
+  if( sqlite3GlobalConfig.bCoreMutex==0 || sqlite3FaultSim(200) ){
+    memset(p, 0, sizeof(*p));
+  }else{
+    p->xTask = xTask;
+    p->pIn = pIn;
+    p->tid = (void*)_beginthreadex(0, 0, sqlite3ThreadProc, p, 0, &p->id);
+    if( p->tid==0 ){
+      memset(p, 0, sizeof(*p));
+    }
+  }
+  if( p->xTask==0 ){
+    p->id = GetCurrentThreadId();
+    p->pResult = xTask(pIn);
+  }
+  *ppThread = p;
+  return SQLITE_OK;
+}
+
+SQLITE_PRIVATE DWORD sqlite3Win32Wait(HANDLE hObject); /* os_win.c */
+
+/* Get the results of the thread */
+SQLITE_PRIVATE int sqlite3ThreadJoin(SQLiteThread *p, void **ppOut){
+  DWORD rc;
+  BOOL bRc;
+
+  assert( ppOut!=0 );
+  if( NEVER(p==0) ) return SQLITE_NOMEM_BKPT;
+  if( p->xTask==0 ){
+    /* assert( p->id==GetCurrentThreadId() ); */
+    rc = WAIT_OBJECT_0;
+    assert( p->tid==0 );
+  }else{
+    assert( p->id!=0 && p->id!=GetCurrentThreadId() );
+    rc = sqlite3Win32Wait((HANDLE)p->tid);
+    assert( rc!=WAIT_IO_COMPLETION );
+    bRc = CloseHandle((HANDLE)p->tid);
+    assert( bRc );
+  }
+  if( rc==WAIT_OBJECT_0 ) *ppOut = p->pResult;
+  sqlite3_free(p);
+  return (rc==WAIT_OBJECT_0) ? SQLITE_OK : SQLITE_ERROR;
+}
+
+#endif /* SQLITE_OS_WIN_THREADS */
+/******************************** End Win32 Threads *************************/
+
+
+/********************************* Single-Threaded **************************/
+#ifndef SQLITE_THREADS_IMPLEMENTED
+/*
+** This implementation does not actually create a new thread.  It does the
+** work of the thread in the main thread, when either the thread is created
+** or when it is joined
+*/
+
+/* A running thread */
+struct SQLiteThread {
+  void *(*xTask)(void*);   /* The routine to run as a thread */
+  void *pIn;               /* Argument to xTask */
+  void *pResult;           /* Result of xTask */
+};
+
+/* Create a new thread */
+SQLITE_PRIVATE int sqlite3ThreadCreate(
+  SQLiteThread **ppThread,  /* OUT: Write the thread object here */
+  void *(*xTask)(void*),    /* Routine to run in a separate thread */
+  void *pIn                 /* Argument passed into xTask() */
+){
+  SQLiteThread *p;
+
+  assert( ppThread!=0 );
+  assert( xTask!=0 );
+  *ppThread = 0;
+  p = sqlite3Malloc(sizeof(*p));
+  if( p==0 ) return SQLITE_NOMEM_BKPT;
+  if( (SQLITE_PTR_TO_INT(p)/17)&1 ){
+    p->xTask = xTask;
+    p->pIn = pIn;
+  }else{
+    p->xTask = 0;
+    p->pResult = xTask(pIn);
+  }
+  *ppThread = p;
+  return SQLITE_OK;
+}
+
+/* Get the results of the thread */
+SQLITE_PRIVATE int sqlite3ThreadJoin(SQLiteThread *p, void **ppOut){
+
+  assert( ppOut!=0 );
+  if( NEVER(p==0) ) return SQLITE_NOMEM_BKPT;
+  if( p->xTask ){
+    *ppOut = p->xTask(p->pIn);
+  }else{
+    *ppOut = p->pResult;
+  }
+  sqlite3_free(p);
+
+#if defined(SQLITE_TEST)
+  {
+    void *pTstAlloc = sqlite3Malloc(10);
+    if (!pTstAlloc) return SQLITE_NOMEM_BKPT;
+    sqlite3_free(pTstAlloc);
+  }
+#endif
+
+  return SQLITE_OK;
+}
+
+#endif /* !defined(SQLITE_THREADS_IMPLEMENTED) */
+/****************************** End Single-Threaded *************************/
+#endif /* SQLITE_MAX_WORKER_THREADS>0 */
+
+/************** End of threads.c *********************************************/
+/************** Begin file utf.c *********************************************/
+/*
+** 2004 April 13
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains routines used to translate between UTF-8, 
+** UTF-16, UTF-16BE, and UTF-16LE.
+**
+** Notes on UTF-8:
+**
+**   Byte-0    Byte-1    Byte-2    Byte-3    Value
+**  0xxxxxxx                                 00000000 00000000 0xxxxxxx
+**  110yyyyy  10xxxxxx                       00000000 00000yyy yyxxxxxx
+**  1110zzzz  10yyyyyy  10xxxxxx             00000000 zzzzyyyy yyxxxxxx
+**  11110uuu  10uuzzzz  10yyyyyy  10xxxxxx   000uuuuu zzzzyyyy yyxxxxxx
+**
+**
+** Notes on UTF-16:  (with wwww+1==uuuuu)
+**
+**      Word-0               Word-1          Value
+**  110110ww wwzzzzyy   110111yy yyxxxxxx    000uuuuu zzzzyyyy yyxxxxxx
+**  zzzzyyyy yyxxxxxx                        00000000 zzzzyyyy yyxxxxxx
+**
+**
+** BOM or Byte Order Mark:
+**     0xff 0xfe   little-endian utf-16 follows
+**     0xfe 0xff   big-endian utf-16 follows
+**
+*/
+/* #include "sqliteInt.h" */
+/* #include <assert.h> */
+/* #include "vdbeInt.h" */
+
+#if !defined(SQLITE_AMALGAMATION) && SQLITE_BYTEORDER==0
+/*
+** The following constant value is used by the SQLITE_BIGENDIAN and
+** SQLITE_LITTLEENDIAN macros.
+*/
+SQLITE_PRIVATE const int sqlite3one = 1;
+#endif /* SQLITE_AMALGAMATION && SQLITE_BYTEORDER==0 */
+
+/*
+** This lookup table is used to help decode the first byte of
+** a multi-byte UTF8 character.
+*/
+static const unsigned char sqlite3Utf8Trans1[] = {
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+  0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+  0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x00, 0x01, 0x02, 0x03, 0x00, 0x01, 0x00, 0x00,
+};
+
+
+#define WRITE_UTF8(zOut, c) {                          \
+  if( c<0x00080 ){                                     \
+    *zOut++ = (u8)(c&0xFF);                            \
+  }                                                    \
+  else if( c<0x00800 ){                                \
+    *zOut++ = 0xC0 + (u8)((c>>6)&0x1F);                \
+    *zOut++ = 0x80 + (u8)(c & 0x3F);                   \
+  }                                                    \
+  else if( c<0x10000 ){                                \
+    *zOut++ = 0xE0 + (u8)((c>>12)&0x0F);               \
+    *zOut++ = 0x80 + (u8)((c>>6) & 0x3F);              \
+    *zOut++ = 0x80 + (u8)(c & 0x3F);                   \
+  }else{                                               \
+    *zOut++ = 0xF0 + (u8)((c>>18) & 0x07);             \
+    *zOut++ = 0x80 + (u8)((c>>12) & 0x3F);             \
+    *zOut++ = 0x80 + (u8)((c>>6) & 0x3F);              \
+    *zOut++ = 0x80 + (u8)(c & 0x3F);                   \
+  }                                                    \
+}
+
+#define WRITE_UTF16LE(zOut, c) {                                    \
+  if( c<=0xFFFF ){                                                  \
+    *zOut++ = (u8)(c&0x00FF);                                       \
+    *zOut++ = (u8)((c>>8)&0x00FF);                                  \
+  }else{                                                            \
+    *zOut++ = (u8)(((c>>10)&0x003F) + (((c-0x10000)>>10)&0x00C0));  \
+    *zOut++ = (u8)(0x00D8 + (((c-0x10000)>>18)&0x03));              \
+    *zOut++ = (u8)(c&0x00FF);                                       \
+    *zOut++ = (u8)(0x00DC + ((c>>8)&0x03));                         \
+  }                                                                 \
+}
+
+#define WRITE_UTF16BE(zOut, c) {                                    \
+  if( c<=0xFFFF ){                                                  \
+    *zOut++ = (u8)((c>>8)&0x00FF);                                  \
+    *zOut++ = (u8)(c&0x00FF);                                       \
+  }else{                                                            \
+    *zOut++ = (u8)(0x00D8 + (((c-0x10000)>>18)&0x03));              \
+    *zOut++ = (u8)(((c>>10)&0x003F) + (((c-0x10000)>>10)&0x00C0));  \
+    *zOut++ = (u8)(0x00DC + ((c>>8)&0x03));                         \
+    *zOut++ = (u8)(c&0x00FF);                                       \
+  }                                                                 \
+}
+
+#define READ_UTF16LE(zIn, TERM, c){                                   \
+  c = (*zIn++);                                                       \
+  c += ((*zIn++)<<8);                                                 \
+  if( c>=0xD800 && c<0xE000 && TERM ){                                \
+    int c2 = (*zIn++);                                                \
+    c2 += ((*zIn++)<<8);                                              \
+    c = (c2&0x03FF) + ((c&0x003F)<<10) + (((c&0x03C0)+0x0040)<<10);   \
+  }                                                                   \
+}
+
+#define READ_UTF16BE(zIn, TERM, c){                                   \
+  c = ((*zIn++)<<8);                                                  \
+  c += (*zIn++);                                                      \
+  if( c>=0xD800 && c<0xE000 && TERM ){                                \
+    int c2 = ((*zIn++)<<8);                                           \
+    c2 += (*zIn++);                                                   \
+    c = (c2&0x03FF) + ((c&0x003F)<<10) + (((c&0x03C0)+0x0040)<<10);   \
+  }                                                                   \
+}
+
+/*
+** Translate a single UTF-8 character.  Return the unicode value.
+**
+** During translation, assume that the byte that zTerm points
+** is a 0x00.
+**
+** Write a pointer to the next unread byte back into *pzNext.
+**
+** Notes On Invalid UTF-8:
+**
+**  *  This routine never allows a 7-bit character (0x00 through 0x7f) to
+**     be encoded as a multi-byte character.  Any multi-byte character that
+**     attempts to encode a value between 0x00 and 0x7f is rendered as 0xfffd.
+**
+**  *  This routine never allows a UTF16 surrogate value to be encoded.
+**     If a multi-byte character attempts to encode a value between
+**     0xd800 and 0xe000 then it is rendered as 0xfffd.
+**
+**  *  Bytes in the range of 0x80 through 0xbf which occur as the first
+**     byte of a character are interpreted as single-byte characters
+**     and rendered as themselves even though they are technically
+**     invalid characters.
+**
+**  *  This routine accepts over-length UTF8 encodings
+**     for unicode values 0x80 and greater.  It does not change over-length
+**     encodings to 0xfffd as some systems recommend.
+*/
+#define READ_UTF8(zIn, zTerm, c)                           \
+  c = *(zIn++);                                            \
+  if( c>=0xc0 ){                                           \
+    c = sqlite3Utf8Trans1[c-0xc0];                         \
+    while( zIn!=zTerm && (*zIn & 0xc0)==0x80 ){            \
+      c = (c<<6) + (0x3f & *(zIn++));                      \
+    }                                                      \
+    if( c<0x80                                             \
+        || (c&0xFFFFF800)==0xD800                          \
+        || (c&0xFFFFFFFE)==0xFFFE ){  c = 0xFFFD; }        \
+  }
+SQLITE_PRIVATE u32 sqlite3Utf8Read(
+  const unsigned char **pz    /* Pointer to string from which to read char */
+){
+  unsigned int c;
+
+  /* Same as READ_UTF8() above but without the zTerm parameter.
+  ** For this routine, we assume the UTF8 string is always zero-terminated.
+  */
+  c = *((*pz)++);
+  if( c>=0xc0 ){
+    c = sqlite3Utf8Trans1[c-0xc0];
+    while( (*(*pz) & 0xc0)==0x80 ){
+      c = (c<<6) + (0x3f & *((*pz)++));
+    }
+    if( c<0x80
+        || (c&0xFFFFF800)==0xD800
+        || (c&0xFFFFFFFE)==0xFFFE ){  c = 0xFFFD; }
+  }
+  return c;
+}
+
+
+
+
+/*
+** If the TRANSLATE_TRACE macro is defined, the value of each Mem is
+** printed on stderr on the way into and out of sqlite3VdbeMemTranslate().
+*/ 
+/* #define TRANSLATE_TRACE 1 */
+
+#ifndef SQLITE_OMIT_UTF16
+/*
+** This routine transforms the internal text encoding used by pMem to
+** desiredEnc. It is an error if the string is already of the desired
+** encoding, or if *pMem does not contain a string value.
+*/
+SQLITE_PRIVATE SQLITE_NOINLINE int sqlite3VdbeMemTranslate(Mem *pMem, u8 desiredEnc){
+  int len;                    /* Maximum length of output string in bytes */
+  unsigned char *zOut;                  /* Output buffer */
+  unsigned char *zIn;                   /* Input iterator */
+  unsigned char *zTerm;                 /* End of input */
+  unsigned char *z;                     /* Output iterator */
+  unsigned int c;
+
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( pMem->flags&MEM_Str );
+  assert( pMem->enc!=desiredEnc );
+  assert( pMem->enc!=0 );
+  assert( pMem->n>=0 );
+
+#if defined(TRANSLATE_TRACE) && defined(SQLITE_DEBUG)
+  {
+    char zBuf[100];
+    sqlite3VdbeMemPrettyPrint(pMem, zBuf);
+    fprintf(stderr, "INPUT:  %s\n", zBuf);
+  }
+#endif
+
+  /* If the translation is between UTF-16 little and big endian, then 
+  ** all that is required is to swap the byte order. This case is handled
+  ** differently from the others.
+  */
+  if( pMem->enc!=SQLITE_UTF8 && desiredEnc!=SQLITE_UTF8 ){
+    u8 temp;
+    int rc;
+    rc = sqlite3VdbeMemMakeWriteable(pMem);
+    if( rc!=SQLITE_OK ){
+      assert( rc==SQLITE_NOMEM );
+      return SQLITE_NOMEM_BKPT;
+    }
+    zIn = (u8*)pMem->z;
+    zTerm = &zIn[pMem->n&~1];
+    while( zIn<zTerm ){
+      temp = *zIn;
+      *zIn = *(zIn+1);
+      zIn++;
+      *zIn++ = temp;
+    }
+    pMem->enc = desiredEnc;
+    goto translate_out;
+  }
+
+  /* Set len to the maximum number of bytes required in the output buffer. */
+  if( desiredEnc==SQLITE_UTF8 ){
+    /* When converting from UTF-16, the maximum growth results from
+    ** translating a 2-byte character to a 4-byte UTF-8 character.
+    ** A single byte is required for the output string
+    ** nul-terminator.
+    */
+    pMem->n &= ~1;
+    len = pMem->n * 2 + 1;
+  }else{
+    /* When converting from UTF-8 to UTF-16 the maximum growth is caused
+    ** when a 1-byte UTF-8 character is translated into a 2-byte UTF-16
+    ** character. Two bytes are required in the output buffer for the
+    ** nul-terminator.
+    */
+    len = pMem->n * 2 + 2;
+  }
+
+  /* Set zIn to point at the start of the input buffer and zTerm to point 1
+  ** byte past the end.
+  **
+  ** Variable zOut is set to point at the output buffer, space obtained
+  ** from sqlite3_malloc().
+  */
+  zIn = (u8*)pMem->z;
+  zTerm = &zIn[pMem->n];
+  zOut = sqlite3DbMallocRaw(pMem->db, len);
+  if( !zOut ){
+    return SQLITE_NOMEM_BKPT;
+  }
+  z = zOut;
+
+  if( pMem->enc==SQLITE_UTF8 ){
+    if( desiredEnc==SQLITE_UTF16LE ){
+      /* UTF-8 -> UTF-16 Little-endian */
+      while( zIn<zTerm ){
+        READ_UTF8(zIn, zTerm, c);
+        WRITE_UTF16LE(z, c);
+      }
+    }else{
+      assert( desiredEnc==SQLITE_UTF16BE );
+      /* UTF-8 -> UTF-16 Big-endian */
+      while( zIn<zTerm ){
+        READ_UTF8(zIn, zTerm, c);
+        WRITE_UTF16BE(z, c);
+      }
+    }
+    pMem->n = (int)(z - zOut);
+    *z++ = 0;
+  }else{
+    assert( desiredEnc==SQLITE_UTF8 );
+    if( pMem->enc==SQLITE_UTF16LE ){
+      /* UTF-16 Little-endian -> UTF-8 */
+      while( zIn<zTerm ){
+        READ_UTF16LE(zIn, zIn<zTerm, c); 
+        WRITE_UTF8(z, c);
+      }
+    }else{
+      /* UTF-16 Big-endian -> UTF-8 */
+      while( zIn<zTerm ){
+        READ_UTF16BE(zIn, zIn<zTerm, c); 
+        WRITE_UTF8(z, c);
+      }
+    }
+    pMem->n = (int)(z - zOut);
+  }
+  *z = 0;
+  assert( (pMem->n+(desiredEnc==SQLITE_UTF8?1:2))<=len );
+
+  c = pMem->flags;
+  sqlite3VdbeMemRelease(pMem);
+  pMem->flags = MEM_Str|MEM_Term|(c&(MEM_AffMask|MEM_Subtype));
+  pMem->enc = desiredEnc;
+  pMem->z = (char*)zOut;
+  pMem->zMalloc = pMem->z;
+  pMem->szMalloc = sqlite3DbMallocSize(pMem->db, pMem->z);
+
+translate_out:
+#if defined(TRANSLATE_TRACE) && defined(SQLITE_DEBUG)
+  {
+    char zBuf[100];
+    sqlite3VdbeMemPrettyPrint(pMem, zBuf);
+    fprintf(stderr, "OUTPUT: %s\n", zBuf);
+  }
+#endif
+  return SQLITE_OK;
+}
+
+/*
+** This routine checks for a byte-order mark at the beginning of the 
+** UTF-16 string stored in *pMem. If one is present, it is removed and
+** the encoding of the Mem adjusted. This routine does not do any
+** byte-swapping, it just sets Mem.enc appropriately.
+**
+** The allocation (static, dynamic etc.) and encoding of the Mem may be
+** changed by this function.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemHandleBom(Mem *pMem){
+  int rc = SQLITE_OK;
+  u8 bom = 0;
+
+  assert( pMem->n>=0 );
+  if( pMem->n>1 ){
+    u8 b1 = *(u8 *)pMem->z;
+    u8 b2 = *(((u8 *)pMem->z) + 1);
+    if( b1==0xFE && b2==0xFF ){
+      bom = SQLITE_UTF16BE;
+    }
+    if( b1==0xFF && b2==0xFE ){
+      bom = SQLITE_UTF16LE;
+    }
+  }
+  
+  if( bom ){
+    rc = sqlite3VdbeMemMakeWriteable(pMem);
+    if( rc==SQLITE_OK ){
+      pMem->n -= 2;
+      memmove(pMem->z, &pMem->z[2], pMem->n);
+      pMem->z[pMem->n] = '\0';
+      pMem->z[pMem->n+1] = '\0';
+      pMem->flags |= MEM_Term;
+      pMem->enc = bom;
+    }
+  }
+  return rc;
+}
+#endif /* SQLITE_OMIT_UTF16 */
+
+/*
+** pZ is a UTF-8 encoded unicode string. If nByte is less than zero,
+** return the number of unicode characters in pZ up to (but not including)
+** the first 0x00 byte. If nByte is not less than zero, return the
+** number of unicode characters in the first nByte of pZ (or up to 
+** the first 0x00, whichever comes first).
+*/
+SQLITE_PRIVATE int sqlite3Utf8CharLen(const char *zIn, int nByte){
+  int r = 0;
+  const u8 *z = (const u8*)zIn;
+  const u8 *zTerm;
+  if( nByte>=0 ){
+    zTerm = &z[nByte];
+  }else{
+    zTerm = (const u8*)(-1);
+  }
+  assert( z<=zTerm );
+  while( *z!=0 && z<zTerm ){
+    SQLITE_SKIP_UTF8(z);
+    r++;
+  }
+  return r;
+}
+
+/* This test function is not currently used by the automated test-suite. 
+** Hence it is only available in debug builds.
+*/
+#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
+/*
+** Translate UTF-8 to UTF-8.
+**
+** This has the effect of making sure that the string is well-formed
+** UTF-8.  Miscoded characters are removed.
+**
+** The translation is done in-place and aborted if the output
+** overruns the input.
+*/
+SQLITE_PRIVATE int sqlite3Utf8To8(unsigned char *zIn){
+  unsigned char *zOut = zIn;
+  unsigned char *zStart = zIn;
+  u32 c;
+
+  while( zIn[0] && zOut<=zIn ){
+    c = sqlite3Utf8Read((const u8**)&zIn);
+    if( c!=0xfffd ){
+      WRITE_UTF8(zOut, c);
+    }
+  }
+  *zOut = 0;
+  return (int)(zOut - zStart);
+}
+#endif
+
+#ifndef SQLITE_OMIT_UTF16
+/*
+** Convert a UTF-16 string in the native encoding into a UTF-8 string.
+** Memory to hold the UTF-8 string is obtained from sqlite3_malloc and must
+** be freed by the calling function.
+**
+** NULL is returned if there is an allocation error.
+*/
+SQLITE_PRIVATE char *sqlite3Utf16to8(sqlite3 *db, const void *z, int nByte, u8 enc){
+  Mem m;
+  memset(&m, 0, sizeof(m));
+  m.db = db;
+  sqlite3VdbeMemSetStr(&m, z, nByte, enc, SQLITE_STATIC);
+  sqlite3VdbeChangeEncoding(&m, SQLITE_UTF8);
+  if( db->mallocFailed ){
+    sqlite3VdbeMemRelease(&m);
+    m.z = 0;
+  }
+  assert( (m.flags & MEM_Term)!=0 || db->mallocFailed );
+  assert( (m.flags & MEM_Str)!=0 || db->mallocFailed );
+  assert( m.z || db->mallocFailed );
+  return m.z;
+}
+
+/*
+** zIn is a UTF-16 encoded unicode string at least nChar characters long.
+** Return the number of bytes in the first nChar unicode characters
+** in pZ.  nChar must be non-negative.
+*/
+SQLITE_PRIVATE int sqlite3Utf16ByteLen(const void *zIn, int nChar){
+  int c;
+  unsigned char const *z = zIn;
+  int n = 0;
+  
+  if( SQLITE_UTF16NATIVE==SQLITE_UTF16BE ){
+    while( n<nChar ){
+      READ_UTF16BE(z, 1, c);
+      n++;
+    }
+  }else{
+    while( n<nChar ){
+      READ_UTF16LE(z, 1, c);
+      n++;
+    }
+  }
+  return (int)(z-(unsigned char const *)zIn);
+}
+
+#if defined(SQLITE_TEST)
+/*
+** This routine is called from the TCL test function "translate_selftest".
+** It checks that the primitives for serializing and deserializing
+** characters in each encoding are inverses of each other.
+*/
+SQLITE_PRIVATE void sqlite3UtfSelfTest(void){
+  unsigned int i, t;
+  unsigned char zBuf[20];
+  unsigned char *z;
+  int n;
+  unsigned int c;
+
+  for(i=0; i<0x00110000; i++){
+    z = zBuf;
+    WRITE_UTF8(z, i);
+    n = (int)(z-zBuf);
+    assert( n>0 && n<=4 );
+    z[0] = 0;
+    z = zBuf;
+    c = sqlite3Utf8Read((const u8**)&z);
+    t = i;
+    if( i>=0xD800 && i<=0xDFFF ) t = 0xFFFD;
+    if( (i&0xFFFFFFFE)==0xFFFE ) t = 0xFFFD;
+    assert( c==t );
+    assert( (z-zBuf)==n );
+  }
+  for(i=0; i<0x00110000; i++){
+    if( i>=0xD800 && i<0xE000 ) continue;
+    z = zBuf;
+    WRITE_UTF16LE(z, i);
+    n = (int)(z-zBuf);
+    assert( n>0 && n<=4 );
+    z[0] = 0;
+    z = zBuf;
+    READ_UTF16LE(z, 1, c);
+    assert( c==i );
+    assert( (z-zBuf)==n );
+  }
+  for(i=0; i<0x00110000; i++){
+    if( i>=0xD800 && i<0xE000 ) continue;
+    z = zBuf;
+    WRITE_UTF16BE(z, i);
+    n = (int)(z-zBuf);
+    assert( n>0 && n<=4 );
+    z[0] = 0;
+    z = zBuf;
+    READ_UTF16BE(z, 1, c);
+    assert( c==i );
+    assert( (z-zBuf)==n );
+  }
+}
+#endif /* SQLITE_TEST */
+#endif /* SQLITE_OMIT_UTF16 */
+
+/************** End of utf.c *************************************************/
+/************** Begin file util.c ********************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** Utility functions used throughout sqlite.
+**
+** This file contains functions for allocating memory, comparing
+** strings, and stuff like that.
+**
+*/
+/* #include "sqliteInt.h" */
+/* #include <stdarg.h> */
+#if HAVE_ISNAN || SQLITE_HAVE_ISNAN
+# include <math.h>
+#endif
+
+/*
+** Routine needed to support the testcase() macro.
+*/
+#ifdef SQLITE_COVERAGE_TEST
+SQLITE_PRIVATE void sqlite3Coverage(int x){
+  static unsigned dummy = 0;
+  dummy += (unsigned)x;
+}
+#endif
+
+/*
+** Give a callback to the test harness that can be used to simulate faults
+** in places where it is difficult or expensive to do so purely by means
+** of inputs.
+**
+** The intent of the integer argument is to let the fault simulator know
+** which of multiple sqlite3FaultSim() calls has been hit.
+**
+** Return whatever integer value the test callback returns, or return
+** SQLITE_OK if no test callback is installed.
+*/
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+SQLITE_PRIVATE int sqlite3FaultSim(int iTest){
+  int (*xCallback)(int) = sqlite3GlobalConfig.xTestCallback;
+  return xCallback ? xCallback(iTest) : SQLITE_OK;
+}
+#endif
+
+#ifndef SQLITE_OMIT_FLOATING_POINT
+/*
+** Return true if the floating point value is Not a Number (NaN).
+**
+** Use the math library isnan() function if compiled with SQLITE_HAVE_ISNAN.
+** Otherwise, we have our own implementation that works on most systems.
+*/
+SQLITE_PRIVATE int sqlite3IsNaN(double x){
+  int rc;   /* The value return */
+#if !SQLITE_HAVE_ISNAN && !HAVE_ISNAN
+  /*
+  ** Systems that support the isnan() library function should probably
+  ** make use of it by compiling with -DSQLITE_HAVE_ISNAN.  But we have
+  ** found that many systems do not have a working isnan() function so
+  ** this implementation is provided as an alternative.
+  **
+  ** This NaN test sometimes fails if compiled on GCC with -ffast-math.
+  ** On the other hand, the use of -ffast-math comes with the following
+  ** warning:
+  **
+  **      This option [-ffast-math] should never be turned on by any
+  **      -O option since it can result in incorrect output for programs
+  **      which depend on an exact implementation of IEEE or ISO 
+  **      rules/specifications for math functions.
+  **
+  ** Under MSVC, this NaN test may fail if compiled with a floating-
+  ** point precision mode other than /fp:precise.  From the MSDN 
+  ** documentation:
+  **
+  **      The compiler [with /fp:precise] will properly handle comparisons 
+  **      involving NaN. For example, x != x evaluates to true if x is NaN 
+  **      ...
+  */
+#ifdef __FAST_MATH__
+# error SQLite will not work correctly with the -ffast-math option of GCC.
+#endif
+  volatile double y = x;
+  volatile double z = y;
+  rc = (y!=z);
+#else  /* if HAVE_ISNAN */
+  rc = isnan(x);
+#endif /* HAVE_ISNAN */
+  testcase( rc );
+  return rc;
+}
+#endif /* SQLITE_OMIT_FLOATING_POINT */
+
+/*
+** Compute a string length that is limited to what can be stored in
+** lower 30 bits of a 32-bit signed integer.
+**
+** The value returned will never be negative.  Nor will it ever be greater
+** than the actual length of the string.  For very long strings (greater
+** than 1GiB) the value returned might be less than the true string length.
+*/
+SQLITE_PRIVATE int sqlite3Strlen30(const char *z){
+  if( z==0 ) return 0;
+  return 0x3fffffff & (int)strlen(z);
+}
+
+/*
+** Return the declared type of a column.  Or return zDflt if the column 
+** has no declared type.
+**
+** The column type is an extra string stored after the zero-terminator on
+** the column name if and only if the COLFLAG_HASTYPE flag is set.
+*/
+SQLITE_PRIVATE char *sqlite3ColumnType(Column *pCol, char *zDflt){
+  if( (pCol->colFlags & COLFLAG_HASTYPE)==0 ) return zDflt;
+  return pCol->zName + strlen(pCol->zName) + 1;
+}
+
+/*
+** Helper function for sqlite3Error() - called rarely.  Broken out into
+** a separate routine to avoid unnecessary register saves on entry to
+** sqlite3Error().
+*/
+static SQLITE_NOINLINE void  sqlite3ErrorFinish(sqlite3 *db, int err_code){
+  if( db->pErr ) sqlite3ValueSetNull(db->pErr);
+  sqlite3SystemError(db, err_code);
+}
+
+/*
+** Set the current error code to err_code and clear any prior error message.
+** Also set iSysErrno (by calling sqlite3System) if the err_code indicates
+** that would be appropriate.
+*/
+SQLITE_PRIVATE void sqlite3Error(sqlite3 *db, int err_code){
+  assert( db!=0 );
+  db->errCode = err_code;
+  if( err_code || db->pErr ) sqlite3ErrorFinish(db, err_code);
+}
+
+/*
+** Load the sqlite3.iSysErrno field if that is an appropriate thing
+** to do based on the SQLite error code in rc.
+*/
+SQLITE_PRIVATE void sqlite3SystemError(sqlite3 *db, int rc){
+  if( rc==SQLITE_IOERR_NOMEM ) return;
+  rc &= 0xff;
+  if( rc==SQLITE_CANTOPEN || rc==SQLITE_IOERR ){
+    db->iSysErrno = sqlite3OsGetLastError(db->pVfs);
+  }
+}
+
+/*
+** Set the most recent error code and error string for the sqlite
+** handle "db". The error code is set to "err_code".
+**
+** If it is not NULL, string zFormat specifies the format of the
+** error string in the style of the printf functions: The following
+** format characters are allowed:
+**
+**      %s      Insert a string
+**      %z      A string that should be freed after use
+**      %d      Insert an integer
+**      %T      Insert a token
+**      %S      Insert the first element of a SrcList
+**
+** zFormat and any string tokens that follow it are assumed to be
+** encoded in UTF-8.
+**
+** To clear the most recent error for sqlite handle "db", sqlite3Error
+** should be called with err_code set to SQLITE_OK and zFormat set
+** to NULL.
+*/
+SQLITE_PRIVATE void sqlite3ErrorWithMsg(sqlite3 *db, int err_code, const char *zFormat, ...){
+  assert( db!=0 );
+  db->errCode = err_code;
+  sqlite3SystemError(db, err_code);
+  if( zFormat==0 ){
+    sqlite3Error(db, err_code);
+  }else if( db->pErr || (db->pErr = sqlite3ValueNew(db))!=0 ){
+    char *z;
+    va_list ap;
+    va_start(ap, zFormat);
+    z = sqlite3VMPrintf(db, zFormat, ap);
+    va_end(ap);
+    sqlite3ValueSetStr(db->pErr, -1, z, SQLITE_UTF8, SQLITE_DYNAMIC);
+  }
+}
+
+/*
+** Add an error message to pParse->zErrMsg and increment pParse->nErr.
+** The following formatting characters are allowed:
+**
+**      %s      Insert a string
+**      %z      A string that should be freed after use
+**      %d      Insert an integer
+**      %T      Insert a token
+**      %S      Insert the first element of a SrcList
+**
+** This function should be used to report any error that occurs while
+** compiling an SQL statement (i.e. within sqlite3_prepare()). The
+** last thing the sqlite3_prepare() function does is copy the error
+** stored by this function into the database handle using sqlite3Error().
+** Functions sqlite3Error() or sqlite3ErrorWithMsg() should be used
+** during statement execution (sqlite3_step() etc.).
+*/
+SQLITE_PRIVATE void sqlite3ErrorMsg(Parse *pParse, const char *zFormat, ...){
+  char *zMsg;
+  va_list ap;
+  sqlite3 *db = pParse->db;
+  va_start(ap, zFormat);
+  zMsg = sqlite3VMPrintf(db, zFormat, ap);
+  va_end(ap);
+  if( db->suppressErr ){
+    sqlite3DbFree(db, zMsg);
+  }else{
+    pParse->nErr++;
+    sqlite3DbFree(db, pParse->zErrMsg);
+    pParse->zErrMsg = zMsg;
+    pParse->rc = SQLITE_ERROR;
+  }
+}
+
+/*
+** Convert an SQL-style quoted string into a normal string by removing
+** the quote characters.  The conversion is done in-place.  If the
+** input does not begin with a quote character, then this routine
+** is a no-op.
+**
+** The input string must be zero-terminated.  A new zero-terminator
+** is added to the dequoted string.
+**
+** The return value is -1 if no dequoting occurs or the length of the
+** dequoted string, exclusive of the zero terminator, if dequoting does
+** occur.
+**
+** 2002-Feb-14: This routine is extended to remove MS-Access style
+** brackets from around identifiers.  For example:  "[a-b-c]" becomes
+** "a-b-c".
+*/
+SQLITE_PRIVATE void sqlite3Dequote(char *z){
+  char quote;
+  int i, j;
+  if( z==0 ) return;
+  quote = z[0];
+  if( !sqlite3Isquote(quote) ) return;
+  if( quote=='[' ) quote = ']';
+  for(i=1, j=0;; i++){
+    assert( z[i] );
+    if( z[i]==quote ){
+      if( z[i+1]==quote ){
+        z[j++] = quote;
+        i++;
+      }else{
+        break;
+      }
+    }else{
+      z[j++] = z[i];
+    }
+  }
+  z[j] = 0;
+}
+
+/*
+** Generate a Token object from a string
+*/
+SQLITE_PRIVATE void sqlite3TokenInit(Token *p, char *z){
+  p->z = z;
+  p->n = sqlite3Strlen30(z);
+}
+
+/* Convenient short-hand */
+#define UpperToLower sqlite3UpperToLower
+
+/*
+** Some systems have stricmp().  Others have strcasecmp().  Because
+** there is no consistency, we will define our own.
+**
+** IMPLEMENTATION-OF: R-30243-02494 The sqlite3_stricmp() and
+** sqlite3_strnicmp() APIs allow applications and extensions to compare
+** the contents of two buffers containing UTF-8 strings in a
+** case-independent fashion, using the same definition of "case
+** independence" that SQLite uses internally when comparing identifiers.
+*/
+SQLITE_API int sqlite3_stricmp(const char *zLeft, const char *zRight){
+  if( zLeft==0 ){
+    return zRight ? -1 : 0;
+  }else if( zRight==0 ){
+    return 1;
+  }
+  return sqlite3StrICmp(zLeft, zRight);
+}
+SQLITE_PRIVATE int sqlite3StrICmp(const char *zLeft, const char *zRight){
+  unsigned char *a, *b;
+  int c;
+  a = (unsigned char *)zLeft;
+  b = (unsigned char *)zRight;
+  for(;;){
+    c = (int)UpperToLower[*a] - (int)UpperToLower[*b];
+    if( c || *a==0 ) break;
+    a++;
+    b++;
+  }
+  return c;
+}
+SQLITE_API int sqlite3_strnicmp(const char *zLeft, const char *zRight, int N){
+  register unsigned char *a, *b;
+  if( zLeft==0 ){
+    return zRight ? -1 : 0;
+  }else if( zRight==0 ){
+    return 1;
+  }
+  a = (unsigned char *)zLeft;
+  b = (unsigned char *)zRight;
+  while( N-- > 0 && *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }
+  return N<0 ? 0 : UpperToLower[*a] - UpperToLower[*b];
+}
+
+/*
+** The string z[] is an text representation of a real number.
+** Convert this string to a double and write it into *pResult.
+**
+** The string z[] is length bytes in length (bytes, not characters) and
+** uses the encoding enc.  The string is not necessarily zero-terminated.
+**
+** Return TRUE if the result is a valid real number (or integer) and FALSE
+** if the string is empty or contains extraneous text.  Valid numbers
+** are in one of these formats:
+**
+**    [+-]digits[E[+-]digits]
+**    [+-]digits.[digits][E[+-]digits]
+**    [+-].digits[E[+-]digits]
+**
+** Leading and trailing whitespace is ignored for the purpose of determining
+** validity.
+**
+** If some prefix of the input string is a valid number, this routine
+** returns FALSE but it still converts the prefix and writes the result
+** into *pResult.
+*/
+SQLITE_PRIVATE int sqlite3AtoF(const char *z, double *pResult, int length, u8 enc){
+#ifndef SQLITE_OMIT_FLOATING_POINT
+  int incr;
+  const char *zEnd = z + length;
+  /* sign * significand * (10 ^ (esign * exponent)) */
+  int sign = 1;    /* sign of significand */
+  i64 s = 0;       /* significand */
+  int d = 0;       /* adjust exponent for shifting decimal point */
+  int esign = 1;   /* sign of exponent */
+  int e = 0;       /* exponent */
+  int eValid = 1;  /* True exponent is either not used or is well-formed */
+  double result;
+  int nDigits = 0;
+  int nonNum = 0;  /* True if input contains UTF16 with high byte non-zero */
+
+  assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
+  *pResult = 0.0;   /* Default return value, in case of an error */
+
+  if( enc==SQLITE_UTF8 ){
+    incr = 1;
+  }else{
+    int i;
+    incr = 2;
+    assert( SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
+    for(i=3-enc; i<length && z[i]==0; i+=2){}
+    nonNum = i<length;
+    zEnd = &z[i^1];
+    z += (enc&1);
+  }
+
+  /* skip leading spaces */
+  while( z<zEnd && sqlite3Isspace(*z) ) z+=incr;
+  if( z>=zEnd ) return 0;
+
+  /* get sign of significand */
+  if( *z=='-' ){
+    sign = -1;
+    z+=incr;
+  }else if( *z=='+' ){
+    z+=incr;
+  }
+
+  /* copy max significant digits to significand */
+  while( z<zEnd && sqlite3Isdigit(*z) && s<((LARGEST_INT64-9)/10) ){
+    s = s*10 + (*z - '0');
+    z+=incr, nDigits++;
+  }
+
+  /* skip non-significant significand digits
+  ** (increase exponent by d to shift decimal left) */
+  while( z<zEnd && sqlite3Isdigit(*z) ) z+=incr, nDigits++, d++;
+  if( z>=zEnd ) goto do_atof_calc;
+
+  /* if decimal point is present */
+  if( *z=='.' ){
+    z+=incr;
+    /* copy digits from after decimal to significand
+    ** (decrease exponent by d to shift decimal right) */
+    while( z<zEnd && sqlite3Isdigit(*z) ){
+      if( s<((LARGEST_INT64-9)/10) ){
+        s = s*10 + (*z - '0');
+        d--;
+      }
+      z+=incr, nDigits++;
+    }
+  }
+  if( z>=zEnd ) goto do_atof_calc;
+
+  /* if exponent is present */
+  if( *z=='e' || *z=='E' ){
+    z+=incr;
+    eValid = 0;
+
+    /* This branch is needed to avoid a (harmless) buffer overread.  The 
+    ** special comment alerts the mutation tester that the correct answer
+    ** is obtained even if the branch is omitted */
+    if( z>=zEnd ) goto do_atof_calc;              /*PREVENTS-HARMLESS-OVERREAD*/
+
+    /* get sign of exponent */
+    if( *z=='-' ){
+      esign = -1;
+      z+=incr;
+    }else if( *z=='+' ){
+      z+=incr;
+    }
+    /* copy digits to exponent */
+    while( z<zEnd && sqlite3Isdigit(*z) ){
+      e = e<10000 ? (e*10 + (*z - '0')) : 10000;
+      z+=incr;
+      eValid = 1;
+    }
+  }
+
+  /* skip trailing spaces */
+  while( z<zEnd && sqlite3Isspace(*z) ) z+=incr;
+
+do_atof_calc:
+  /* adjust exponent by d, and update sign */
+  e = (e*esign) + d;
+  if( e<0 ) {
+    esign = -1;
+    e *= -1;
+  } else {
+    esign = 1;
+  }
+
+  if( s==0 ) {
+    /* In the IEEE 754 standard, zero is signed. */
+    result = sign<0 ? -(double)0 : (double)0;
+  } else {
+    /* Attempt to reduce exponent.
+    **
+    ** Branches that are not required for the correct answer but which only
+    ** help to obtain the correct answer faster are marked with special
+    ** comments, as a hint to the mutation tester.
+    */
+    while( e>0 ){                                       /*OPTIMIZATION-IF-TRUE*/
+      if( esign>0 ){
+        if( s>=(LARGEST_INT64/10) ) break;             /*OPTIMIZATION-IF-FALSE*/
+        s *= 10;
+      }else{
+        if( s%10!=0 ) break;                           /*OPTIMIZATION-IF-FALSE*/
+        s /= 10;
+      }
+      e--;
+    }
+
+    /* adjust the sign of significand */
+    s = sign<0 ? -s : s;
+
+    if( e==0 ){                                         /*OPTIMIZATION-IF-TRUE*/
+      result = (double)s;
+    }else{
+      LONGDOUBLE_TYPE scale = 1.0;
+      /* attempt to handle extremely small/large numbers better */
+      if( e>307 ){                                      /*OPTIMIZATION-IF-TRUE*/
+        if( e<342 ){                                    /*OPTIMIZATION-IF-TRUE*/
+          while( e%308 ) { scale *= 1.0e+1; e -= 1; }
+          if( esign<0 ){
+            result = s / scale;
+            result /= 1.0e+308;
+          }else{
+            result = s * scale;
+            result *= 1.0e+308;
+          }
+        }else{ assert( e>=342 );
+          if( esign<0 ){
+            result = 0.0*s;
+          }else{
+            result = 1e308*1e308*s;  /* Infinity */
+          }
+        }
+      }else{
+        /* 1.0e+22 is the largest power of 10 than can be 
+        ** represented exactly. */
+        while( e%22 ) { scale *= 1.0e+1; e -= 1; }
+        while( e>0 ) { scale *= 1.0e+22; e -= 22; }
+        if( esign<0 ){
+          result = s / scale;
+        }else{
+          result = s * scale;
+        }
+      }
+    }
+  }
+
+  /* store the result */
+  *pResult = result;
+
+  /* return true if number and no extra non-whitespace chracters after */
+  return z==zEnd && nDigits>0 && eValid && nonNum==0;
+#else
+  return !sqlite3Atoi64(z, pResult, length, enc);
+#endif /* SQLITE_OMIT_FLOATING_POINT */
+}
+
+/*
+** Compare the 19-character string zNum against the text representation
+** value 2^63:  9223372036854775808.  Return negative, zero, or positive
+** if zNum is less than, equal to, or greater than the string.
+** Note that zNum must contain exactly 19 characters.
+**
+** Unlike memcmp() this routine is guaranteed to return the difference
+** in the values of the last digit if the only difference is in the
+** last digit.  So, for example,
+**
+**      compare2pow63("9223372036854775800", 1)
+**
+** will return -8.
+*/
+static int compare2pow63(const char *zNum, int incr){
+  int c = 0;
+  int i;
+                    /* 012345678901234567 */
+  const char *pow63 = "922337203685477580";
+  for(i=0; c==0 && i<18; i++){
+    c = (zNum[i*incr]-pow63[i])*10;
+  }
+  if( c==0 ){
+    c = zNum[18*incr] - '8';
+    testcase( c==(-1) );
+    testcase( c==0 );
+    testcase( c==(+1) );
+  }
+  return c;
+}
+
+/*
+** Convert zNum to a 64-bit signed integer.  zNum must be decimal. This
+** routine does *not* accept hexadecimal notation.
+**
+** If the zNum value is representable as a 64-bit twos-complement 
+** integer, then write that value into *pNum and return 0.
+**
+** If zNum is exactly 9223372036854775808, return 2.  This special
+** case is broken out because while 9223372036854775808 cannot be a 
+** signed 64-bit integer, its negative -9223372036854775808 can be.
+**
+** If zNum is too big for a 64-bit integer and is not
+** 9223372036854775808  or if zNum contains any non-numeric text,
+** then return 1.
+**
+** length is the number of bytes in the string (bytes, not characters).
+** The string is not necessarily zero-terminated.  The encoding is
+** given by enc.
+*/
+SQLITE_PRIVATE int sqlite3Atoi64(const char *zNum, i64 *pNum, int length, u8 enc){
+  int incr;
+  u64 u = 0;
+  int neg = 0; /* assume positive */
+  int i;
+  int c = 0;
+  int nonNum = 0;  /* True if input contains UTF16 with high byte non-zero */
+  const char *zStart;
+  const char *zEnd = zNum + length;
+  assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
+  if( enc==SQLITE_UTF8 ){
+    incr = 1;
+  }else{
+    incr = 2;
+    assert( SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
+    for(i=3-enc; i<length && zNum[i]==0; i+=2){}
+    nonNum = i<length;
+    zEnd = &zNum[i^1];
+    zNum += (enc&1);
+  }
+  while( zNum<zEnd && sqlite3Isspace(*zNum) ) zNum+=incr;
+  if( zNum<zEnd ){
+    if( *zNum=='-' ){
+      neg = 1;
+      zNum+=incr;
+    }else if( *zNum=='+' ){
+      zNum+=incr;
+    }
+  }
+  zStart = zNum;
+  while( zNum<zEnd && zNum[0]=='0' ){ zNum+=incr; } /* Skip leading zeros. */
+  for(i=0; &zNum[i]<zEnd && (c=zNum[i])>='0' && c<='9'; i+=incr){
+    u = u*10 + c - '0';
+  }
+  if( u>LARGEST_INT64 ){
+    *pNum = neg ? SMALLEST_INT64 : LARGEST_INT64;
+  }else if( neg ){
+    *pNum = -(i64)u;
+  }else{
+    *pNum = (i64)u;
+  }
+  testcase( i==18 );
+  testcase( i==19 );
+  testcase( i==20 );
+  if( &zNum[i]<zEnd              /* Extra bytes at the end */
+   || (i==0 && zStart==zNum)     /* No digits */
+   || i>19*incr                  /* Too many digits */
+   || nonNum                     /* UTF16 with high-order bytes non-zero */
+  ){
+    /* zNum is empty or contains non-numeric text or is longer
+    ** than 19 digits (thus guaranteeing that it is too large) */
+    return 1;
+  }else if( i<19*incr ){
+    /* Less than 19 digits, so we know that it fits in 64 bits */
+    assert( u<=LARGEST_INT64 );
+    return 0;
+  }else{
+    /* zNum is a 19-digit numbers.  Compare it against 9223372036854775808. */
+    c = compare2pow63(zNum, incr);
+    if( c<0 ){
+      /* zNum is less than 9223372036854775808 so it fits */
+      assert( u<=LARGEST_INT64 );
+      return 0;
+    }else if( c>0 ){
+      /* zNum is greater than 9223372036854775808 so it overflows */
+      return 1;
+    }else{
+      /* zNum is exactly 9223372036854775808.  Fits if negative.  The
+      ** special case 2 overflow if positive */
+      assert( u-1==LARGEST_INT64 );
+      return neg ? 0 : 2;
+    }
+  }
+}
+
+/*
+** Transform a UTF-8 integer literal, in either decimal or hexadecimal,
+** into a 64-bit signed integer.  This routine accepts hexadecimal literals,
+** whereas sqlite3Atoi64() does not.
+**
+** Returns:
+**
+**     0    Successful transformation.  Fits in a 64-bit signed integer.
+**     1    Integer too large for a 64-bit signed integer or is malformed
+**     2    Special case of 9223372036854775808
+*/
+SQLITE_PRIVATE int sqlite3DecOrHexToI64(const char *z, i64 *pOut){
+#ifndef SQLITE_OMIT_HEX_INTEGER
+  if( z[0]=='0'
+   && (z[1]=='x' || z[1]=='X')
+  ){
+    u64 u = 0;
+    int i, k;
+    for(i=2; z[i]=='0'; i++){}
+    for(k=i; sqlite3Isxdigit(z[k]); k++){
+      u = u*16 + sqlite3HexToInt(z[k]);
+    }
+    memcpy(pOut, &u, 8);
+    return (z[k]==0 && k-i<=16) ? 0 : 1;
+  }else
+#endif /* SQLITE_OMIT_HEX_INTEGER */
+  {
+    return sqlite3Atoi64(z, pOut, sqlite3Strlen30(z), SQLITE_UTF8);
+  }
+}
+
+/*
+** If zNum represents an integer that will fit in 32-bits, then set
+** *pValue to that integer and return true.  Otherwise return false.
+**
+** This routine accepts both decimal and hexadecimal notation for integers.
+**
+** Any non-numeric characters that following zNum are ignored.
+** This is different from sqlite3Atoi64() which requires the
+** input number to be zero-terminated.
+*/
+SQLITE_PRIVATE int sqlite3GetInt32(const char *zNum, int *pValue){
+  sqlite_int64 v = 0;
+  int i, c;
+  int neg = 0;
+  if( zNum[0]=='-' ){
+    neg = 1;
+    zNum++;
+  }else if( zNum[0]=='+' ){
+    zNum++;
+  }
+#ifndef SQLITE_OMIT_HEX_INTEGER
+  else if( zNum[0]=='0'
+        && (zNum[1]=='x' || zNum[1]=='X')
+        && sqlite3Isxdigit(zNum[2])
+  ){
+    u32 u = 0;
+    zNum += 2;
+    while( zNum[0]=='0' ) zNum++;
+    for(i=0; sqlite3Isxdigit(zNum[i]) && i<8; i++){
+      u = u*16 + sqlite3HexToInt(zNum[i]);
+    }
+    if( (u&0x80000000)==0 && sqlite3Isxdigit(zNum[i])==0 ){
+      memcpy(pValue, &u, 4);
+      return 1;
+    }else{
+      return 0;
+    }
+  }
+#endif
+  while( zNum[0]=='0' ) zNum++;
+  for(i=0; i<11 && (c = zNum[i] - '0')>=0 && c<=9; i++){
+    v = v*10 + c;
+  }
+
+  /* The longest decimal representation of a 32 bit integer is 10 digits:
+  **
+  **             1234567890
+  **     2^31 -> 2147483648
+  */
+  testcase( i==10 );
+  if( i>10 ){
+    return 0;
+  }
+  testcase( v-neg==2147483647 );
+  if( v-neg>2147483647 ){
+    return 0;
+  }
+  if( neg ){
+    v = -v;
+  }
+  *pValue = (int)v;
+  return 1;
+}
+
+/*
+** Return a 32-bit integer value extracted from a string.  If the
+** string is not an integer, just return 0.
+*/
+SQLITE_PRIVATE int sqlite3Atoi(const char *z){
+  int x = 0;
+  if( z ) sqlite3GetInt32(z, &x);
+  return x;
+}
+
+/*
+** The variable-length integer encoding is as follows:
+**
+** KEY:
+**         A = 0xxxxxxx    7 bits of data and one flag bit
+**         B = 1xxxxxxx    7 bits of data and one flag bit
+**         C = xxxxxxxx    8 bits of data
+**
+**  7 bits - A
+** 14 bits - BA
+** 21 bits - BBA
+** 28 bits - BBBA
+** 35 bits - BBBBA
+** 42 bits - BBBBBA
+** 49 bits - BBBBBBA
+** 56 bits - BBBBBBBA
+** 64 bits - BBBBBBBBC
+*/
+
+/*
+** Write a 64-bit variable-length integer to memory starting at p[0].
+** The length of data write will be between 1 and 9 bytes.  The number
+** of bytes written is returned.
+**
+** A variable-length integer consists of the lower 7 bits of each byte
+** for all bytes that have the 8th bit set and one byte with the 8th
+** bit clear.  Except, if we get to the 9th byte, it stores the full
+** 8 bits and is the last byte.
+*/
+static int SQLITE_NOINLINE putVarint64(unsigned char *p, u64 v){
+  int i, j, n;
+  u8 buf[10];
+  if( v & (((u64)0xff000000)<<32) ){
+    p[8] = (u8)v;
+    v >>= 8;
+    for(i=7; i>=0; i--){
+      p[i] = (u8)((v & 0x7f) | 0x80);
+      v >>= 7;
+    }
+    return 9;
+  }    
+  n = 0;
+  do{
+    buf[n++] = (u8)((v & 0x7f) | 0x80);
+    v >>= 7;
+  }while( v!=0 );
+  buf[0] &= 0x7f;
+  assert( n<=9 );
+  for(i=0, j=n-1; j>=0; j--, i++){
+    p[i] = buf[j];
+  }
+  return n;
+}
+SQLITE_PRIVATE int sqlite3PutVarint(unsigned char *p, u64 v){
+  if( v<=0x7f ){
+    p[0] = v&0x7f;
+    return 1;
+  }
+  if( v<=0x3fff ){
+    p[0] = ((v>>7)&0x7f)|0x80;
+    p[1] = v&0x7f;
+    return 2;
+  }
+  return putVarint64(p,v);
+}
+
+/*
+** Bitmasks used by sqlite3GetVarint().  These precomputed constants
+** are defined here rather than simply putting the constant expressions
+** inline in order to work around bugs in the RVT compiler.
+**
+** SLOT_2_0     A mask for  (0x7f<<14) | 0x7f
+**
+** SLOT_4_2_0   A mask for  (0x7f<<28) | SLOT_2_0
+*/
+#define SLOT_2_0     0x001fc07f
+#define SLOT_4_2_0   0xf01fc07f
+
+
+/*
+** Read a 64-bit variable-length integer from memory starting at p[0].
+** Return the number of bytes read.  The value is stored in *v.
+*/
+SQLITE_PRIVATE u8 sqlite3GetVarint(const unsigned char *p, u64 *v){
+  u32 a,b,s;
+
+  a = *p;
+  /* a: p0 (unmasked) */
+  if (!(a&0x80))
+  {
+    *v = a;
+    return 1;
+  }
+
+  p++;
+  b = *p;
+  /* b: p1 (unmasked) */
+  if (!(b&0x80))
+  {
+    a &= 0x7f;
+    a = a<<7;
+    a |= b;
+    *v = a;
+    return 2;
+  }
+
+  /* Verify that constants are precomputed correctly */
+  assert( SLOT_2_0 == ((0x7f<<14) | (0x7f)) );
+  assert( SLOT_4_2_0 == ((0xfU<<28) | (0x7f<<14) | (0x7f)) );
+
+  p++;
+  a = a<<14;
+  a |= *p;
+  /* a: p0<<14 | p2 (unmasked) */
+  if (!(a&0x80))
+  {
+    a &= SLOT_2_0;
+    b &= 0x7f;
+    b = b<<7;
+    a |= b;
+    *v = a;
+    return 3;
+  }
+
+  /* CSE1 from below */
+  a &= SLOT_2_0;
+  p++;
+  b = b<<14;
+  b |= *p;
+  /* b: p1<<14 | p3 (unmasked) */
+  if (!(b&0x80))
+  {
+    b &= SLOT_2_0;
+    /* moved CSE1 up */
+    /* a &= (0x7f<<14)|(0x7f); */
+    a = a<<7;
+    a |= b;
+    *v = a;
+    return 4;
+  }
+
+  /* a: p0<<14 | p2 (masked) */
+  /* b: p1<<14 | p3 (unmasked) */
+  /* 1:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
+  /* moved CSE1 up */
+  /* a &= (0x7f<<14)|(0x7f); */
+  b &= SLOT_2_0;
+  s = a;
+  /* s: p0<<14 | p2 (masked) */
+
+  p++;
+  a = a<<14;
+  a |= *p;
+  /* a: p0<<28 | p2<<14 | p4 (unmasked) */
+  if (!(a&0x80))
+  {
+    /* we can skip these cause they were (effectively) done above
+    ** while calculating s */
+    /* a &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
+    /* b &= (0x7f<<14)|(0x7f); */
+    b = b<<7;
+    a |= b;
+    s = s>>18;
+    *v = ((u64)s)<<32 | a;
+    return 5;
+  }
+
+  /* 2:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
+  s = s<<7;
+  s |= b;
+  /* s: p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
+
+  p++;
+  b = b<<14;
+  b |= *p;
+  /* b: p1<<28 | p3<<14 | p5 (unmasked) */
+  if (!(b&0x80))
+  {
+    /* we can skip this cause it was (effectively) done above in calc'ing s */
+    /* b &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
+    a &= SLOT_2_0;
+    a = a<<7;
+    a |= b;
+    s = s>>18;
+    *v = ((u64)s)<<32 | a;
+    return 6;
+  }
+
+  p++;
+  a = a<<14;
+  a |= *p;
+  /* a: p2<<28 | p4<<14 | p6 (unmasked) */
+  if (!(a&0x80))
+  {
+    a &= SLOT_4_2_0;
+    b &= SLOT_2_0;
+    b = b<<7;
+    a |= b;
+    s = s>>11;
+    *v = ((u64)s)<<32 | a;
+    return 7;
+  }
+
+  /* CSE2 from below */
+  a &= SLOT_2_0;
+  p++;
+  b = b<<14;
+  b |= *p;
+  /* b: p3<<28 | p5<<14 | p7 (unmasked) */
+  if (!(b&0x80))
+  {
+    b &= SLOT_4_2_0;
+    /* moved CSE2 up */
+    /* a &= (0x7f<<14)|(0x7f); */
+    a = a<<7;
+    a |= b;
+    s = s>>4;
+    *v = ((u64)s)<<32 | a;
+    return 8;
+  }
+
+  p++;
+  a = a<<15;
+  a |= *p;
+  /* a: p4<<29 | p6<<15 | p8 (unmasked) */
+
+  /* moved CSE2 up */
+  /* a &= (0x7f<<29)|(0x7f<<15)|(0xff); */
+  b &= SLOT_2_0;
+  b = b<<8;
+  a |= b;
+
+  s = s<<4;
+  b = p[-4];
+  b &= 0x7f;
+  b = b>>3;
+  s |= b;
+
+  *v = ((u64)s)<<32 | a;
+
+  return 9;
+}
+
+/*
+** Read a 32-bit variable-length integer from memory starting at p[0].
+** Return the number of bytes read.  The value is stored in *v.
+**
+** If the varint stored in p[0] is larger than can fit in a 32-bit unsigned
+** integer, then set *v to 0xffffffff.
+**
+** A MACRO version, getVarint32, is provided which inlines the 
+** single-byte case.  All code should use the MACRO version as 
+** this function assumes the single-byte case has already been handled.
+*/
+SQLITE_PRIVATE u8 sqlite3GetVarint32(const unsigned char *p, u32 *v){
+  u32 a,b;
+
+  /* The 1-byte case.  Overwhelmingly the most common.  Handled inline
+  ** by the getVarin32() macro */
+  a = *p;
+  /* a: p0 (unmasked) */
+#ifndef getVarint32
+  if (!(a&0x80))
+  {
+    /* Values between 0 and 127 */
+    *v = a;
+    return 1;
+  }
+#endif
+
+  /* The 2-byte case */
+  p++;
+  b = *p;
+  /* b: p1 (unmasked) */
+  if (!(b&0x80))
+  {
+    /* Values between 128 and 16383 */
+    a &= 0x7f;
+    a = a<<7;
+    *v = a | b;
+    return 2;
+  }
+
+  /* The 3-byte case */
+  p++;
+  a = a<<14;
+  a |= *p;
+  /* a: p0<<14 | p2 (unmasked) */
+  if (!(a&0x80))
+  {
+    /* Values between 16384 and 2097151 */
+    a &= (0x7f<<14)|(0x7f);
+    b &= 0x7f;
+    b = b<<7;
+    *v = a | b;
+    return 3;
+  }
+
+  /* A 32-bit varint is used to store size information in btrees.
+  ** Objects are rarely larger than 2MiB limit of a 3-byte varint.
+  ** A 3-byte varint is sufficient, for example, to record the size
+  ** of a 1048569-byte BLOB or string.
+  **
+  ** We only unroll the first 1-, 2-, and 3- byte cases.  The very
+  ** rare larger cases can be handled by the slower 64-bit varint
+  ** routine.
+  */
+#if 1
+  {
+    u64 v64;
+    u8 n;
+
+    p -= 2;
+    n = sqlite3GetVarint(p, &v64);
+    assert( n>3 && n<=9 );
+    if( (v64 & SQLITE_MAX_U32)!=v64 ){
+      *v = 0xffffffff;
+    }else{
+      *v = (u32)v64;
+    }
+    return n;
+  }
+
+#else
+  /* For following code (kept for historical record only) shows an
+  ** unrolling for the 3- and 4-byte varint cases.  This code is
+  ** slightly faster, but it is also larger and much harder to test.
+  */
+  p++;
+  b = b<<14;
+  b |= *p;
+  /* b: p1<<14 | p3 (unmasked) */
+  if (!(b&0x80))
+  {
+    /* Values between 2097152 and 268435455 */
+    b &= (0x7f<<14)|(0x7f);
+    a &= (0x7f<<14)|(0x7f);
+    a = a<<7;
+    *v = a | b;
+    return 4;
+  }
+
+  p++;
+  a = a<<14;
+  a |= *p;
+  /* a: p0<<28 | p2<<14 | p4 (unmasked) */
+  if (!(a&0x80))
+  {
+    /* Values  between 268435456 and 34359738367 */
+    a &= SLOT_4_2_0;
+    b &= SLOT_4_2_0;
+    b = b<<7;
+    *v = a | b;
+    return 5;
+  }
+
+  /* We can only reach this point when reading a corrupt database
+  ** file.  In that case we are not in any hurry.  Use the (relatively
+  ** slow) general-purpose sqlite3GetVarint() routine to extract the
+  ** value. */
+  {
+    u64 v64;
+    u8 n;
+
+    p -= 4;
+    n = sqlite3GetVarint(p, &v64);
+    assert( n>5 && n<=9 );
+    *v = (u32)v64;
+    return n;
+  }
+#endif
+}
+
+/*
+** Return the number of bytes that will be needed to store the given
+** 64-bit integer.
+*/
+SQLITE_PRIVATE int sqlite3VarintLen(u64 v){
+  int i;
+  for(i=1; (v >>= 7)!=0; i++){ assert( i<10 ); }
+  return i;
+}
+
+
+/*
+** Read or write a four-byte big-endian integer value.
+*/
+SQLITE_PRIVATE u32 sqlite3Get4byte(const u8 *p){
+#if SQLITE_BYTEORDER==4321
+  u32 x;
+  memcpy(&x,p,4);
+  return x;
+#elif SQLITE_BYTEORDER==1234 && !defined(SQLITE_DISABLE_INTRINSIC) \
+    && defined(__GNUC__) && GCC_VERSION>=4003000
+  u32 x;
+  memcpy(&x,p,4);
+  return __builtin_bswap32(x);
+#elif SQLITE_BYTEORDER==1234 && !defined(SQLITE_DISABLE_INTRINSIC) \
+    && defined(_MSC_VER) && _MSC_VER>=1300
+  u32 x;
+  memcpy(&x,p,4);
+  return _byteswap_ulong(x);
+#else
+  testcase( p[0]&0x80 );
+  return ((unsigned)p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
+#endif
+}
+SQLITE_PRIVATE void sqlite3Put4byte(unsigned char *p, u32 v){
+#if SQLITE_BYTEORDER==4321
+  memcpy(p,&v,4);
+#elif SQLITE_BYTEORDER==1234 && !defined(SQLITE_DISABLE_INTRINSIC) \
+    && defined(__GNUC__) && GCC_VERSION>=4003000
+  u32 x = __builtin_bswap32(v);
+  memcpy(p,&x,4);
+#elif SQLITE_BYTEORDER==1234 && !defined(SQLITE_DISABLE_INTRINSIC) \
+    && defined(_MSC_VER) && _MSC_VER>=1300
+  u32 x = _byteswap_ulong(v);
+  memcpy(p,&x,4);
+#else
+  p[0] = (u8)(v>>24);
+  p[1] = (u8)(v>>16);
+  p[2] = (u8)(v>>8);
+  p[3] = (u8)v;
+#endif
+}
+
+
+
+/*
+** Translate a single byte of Hex into an integer.
+** This routine only works if h really is a valid hexadecimal
+** character:  0..9a..fA..F
+*/
+SQLITE_PRIVATE u8 sqlite3HexToInt(int h){
+  assert( (h>='0' && h<='9') ||  (h>='a' && h<='f') ||  (h>='A' && h<='F') );
+#ifdef SQLITE_ASCII
+  h += 9*(1&(h>>6));
+#endif
+#ifdef SQLITE_EBCDIC
+  h += 9*(1&~(h>>4));
+#endif
+  return (u8)(h & 0xf);
+}
+
+#if !defined(SQLITE_OMIT_BLOB_LITERAL) || defined(SQLITE_HAS_CODEC)
+/*
+** Convert a BLOB literal of the form "x'hhhhhh'" into its binary
+** value.  Return a pointer to its binary value.  Space to hold the
+** binary value has been obtained from malloc and must be freed by
+** the calling routine.
+*/
+SQLITE_PRIVATE void *sqlite3HexToBlob(sqlite3 *db, const char *z, int n){
+  char *zBlob;
+  int i;
+
+  zBlob = (char *)sqlite3DbMallocRawNN(db, n/2 + 1);
+  n--;
+  if( zBlob ){
+    for(i=0; i<n; i+=2){
+      zBlob[i/2] = (sqlite3HexToInt(z[i])<<4) | sqlite3HexToInt(z[i+1]);
+    }
+    zBlob[i/2] = 0;
+  }
+  return zBlob;
+}
+#endif /* !SQLITE_OMIT_BLOB_LITERAL || SQLITE_HAS_CODEC */
+
+/*
+** Log an error that is an API call on a connection pointer that should
+** not have been used.  The "type" of connection pointer is given as the
+** argument.  The zType is a word like "NULL" or "closed" or "invalid".
+*/
+static void logBadConnection(const char *zType){
+  sqlite3_log(SQLITE_MISUSE, 
+     "API call with %s database connection pointer",
+     zType
+  );
+}
+
+/*
+** Check to make sure we have a valid db pointer.  This test is not
+** foolproof but it does provide some measure of protection against
+** misuse of the interface such as passing in db pointers that are
+** NULL or which have been previously closed.  If this routine returns
+** 1 it means that the db pointer is valid and 0 if it should not be
+** dereferenced for any reason.  The calling function should invoke
+** SQLITE_MISUSE immediately.
+**
+** sqlite3SafetyCheckOk() requires that the db pointer be valid for
+** use.  sqlite3SafetyCheckSickOrOk() allows a db pointer that failed to
+** open properly and is not fit for general use but which can be
+** used as an argument to sqlite3_errmsg() or sqlite3_close().
+*/
+SQLITE_PRIVATE int sqlite3SafetyCheckOk(sqlite3 *db){
+  u32 magic;
+  if( db==0 ){
+    logBadConnection("NULL");
+    return 0;
+  }
+  magic = db->magic;
+  if( magic!=SQLITE_MAGIC_OPEN ){
+    if( sqlite3SafetyCheckSickOrOk(db) ){
+      testcase( sqlite3GlobalConfig.xLog!=0 );
+      logBadConnection("unopened");
+    }
+    return 0;
+  }else{
+    return 1;
+  }
+}
+SQLITE_PRIVATE int sqlite3SafetyCheckSickOrOk(sqlite3 *db){
+  u32 magic;
+  magic = db->magic;
+  if( magic!=SQLITE_MAGIC_SICK &&
+      magic!=SQLITE_MAGIC_OPEN &&
+      magic!=SQLITE_MAGIC_BUSY ){
+    testcase( sqlite3GlobalConfig.xLog!=0 );
+    logBadConnection("invalid");
+    return 0;
+  }else{
+    return 1;
+  }
+}
+
+/*
+** Attempt to add, substract, or multiply the 64-bit signed value iB against
+** the other 64-bit signed integer at *pA and store the result in *pA.
+** Return 0 on success.  Or if the operation would have resulted in an
+** overflow, leave *pA unchanged and return 1.
+*/
+SQLITE_PRIVATE int sqlite3AddInt64(i64 *pA, i64 iB){
+  i64 iA = *pA;
+  testcase( iA==0 ); testcase( iA==1 );
+  testcase( iB==-1 ); testcase( iB==0 );
+  if( iB>=0 ){
+    testcase( iA>0 && LARGEST_INT64 - iA == iB );
+    testcase( iA>0 && LARGEST_INT64 - iA == iB - 1 );
+    if( iA>0 && LARGEST_INT64 - iA < iB ) return 1;
+  }else{
+    testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 1 );
+    testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 2 );
+    if( iA<0 && -(iA + LARGEST_INT64) > iB + 1 ) return 1;
+  }
+  *pA += iB;
+  return 0; 
+}
+SQLITE_PRIVATE int sqlite3SubInt64(i64 *pA, i64 iB){
+  testcase( iB==SMALLEST_INT64+1 );
+  if( iB==SMALLEST_INT64 ){
+    testcase( (*pA)==(-1) ); testcase( (*pA)==0 );
+    if( (*pA)>=0 ) return 1;
+    *pA -= iB;
+    return 0;
+  }else{
+    return sqlite3AddInt64(pA, -iB);
+  }
+}
+SQLITE_PRIVATE int sqlite3MulInt64(i64 *pA, i64 iB){
+  i64 iA = *pA;
+  if( iB>0 ){
+    if( iA>LARGEST_INT64/iB ) return 1;
+    if( iA<SMALLEST_INT64/iB ) return 1;
+  }else if( iB<0 ){
+    if( iA>0 ){
+      if( iB<SMALLEST_INT64/iA ) return 1;
+    }else if( iA<0 ){
+      if( iB==SMALLEST_INT64 ) return 1;
+      if( iA==SMALLEST_INT64 ) return 1;
+      if( -iA>LARGEST_INT64/-iB ) return 1;
+    }
+  }
+  *pA = iA*iB;
+  return 0;
+}
+
+/*
+** Compute the absolute value of a 32-bit signed integer, of possible.  Or 
+** if the integer has a value of -2147483648, return +2147483647
+*/
+SQLITE_PRIVATE int sqlite3AbsInt32(int x){
+  if( x>=0 ) return x;
+  if( x==(int)0x80000000 ) return 0x7fffffff;
+  return -x;
+}
+
+#ifdef SQLITE_ENABLE_8_3_NAMES
+/*
+** If SQLITE_ENABLE_8_3_NAMES is set at compile-time and if the database
+** filename in zBaseFilename is a URI with the "8_3_names=1" parameter and
+** if filename in z[] has a suffix (a.k.a. "extension") that is longer than
+** three characters, then shorten the suffix on z[] to be the last three
+** characters of the original suffix.
+**
+** If SQLITE_ENABLE_8_3_NAMES is set to 2 at compile-time, then always
+** do the suffix shortening regardless of URI parameter.
+**
+** Examples:
+**
+**     test.db-journal    =>   test.nal
+**     test.db-wal        =>   test.wal
+**     test.db-shm        =>   test.shm
+**     test.db-mj7f3319fa =>   test.9fa
+*/
+SQLITE_PRIVATE void sqlite3FileSuffix3(const char *zBaseFilename, char *z){
+#if SQLITE_ENABLE_8_3_NAMES<2
+  if( sqlite3_uri_boolean(zBaseFilename, "8_3_names", 0) )
+#endif
+  {
+    int i, sz;
+    sz = sqlite3Strlen30(z);
+    for(i=sz-1; i>0 && z[i]!='/' && z[i]!='.'; i--){}
+    if( z[i]=='.' && ALWAYS(sz>i+4) ) memmove(&z[i+1], &z[sz-3], 4);
+  }
+}
+#endif
+
+/* 
+** Find (an approximate) sum of two LogEst values.  This computation is
+** not a simple "+" operator because LogEst is stored as a logarithmic
+** value.
+** 
+*/
+SQLITE_PRIVATE LogEst sqlite3LogEstAdd(LogEst a, LogEst b){
+  static const unsigned char x[] = {
+     10, 10,                         /* 0,1 */
+      9, 9,                          /* 2,3 */
+      8, 8,                          /* 4,5 */
+      7, 7, 7,                       /* 6,7,8 */
+      6, 6, 6,                       /* 9,10,11 */
+      5, 5, 5,                       /* 12-14 */
+      4, 4, 4, 4,                    /* 15-18 */
+      3, 3, 3, 3, 3, 3,              /* 19-24 */
+      2, 2, 2, 2, 2, 2, 2,           /* 25-31 */
+  };
+  if( a>=b ){
+    if( a>b+49 ) return a;
+    if( a>b+31 ) return a+1;
+    return a+x[a-b];
+  }else{
+    if( b>a+49 ) return b;
+    if( b>a+31 ) return b+1;
+    return b+x[b-a];
+  }
+}
+
+/*
+** Convert an integer into a LogEst.  In other words, compute an
+** approximation for 10*log2(x).
+*/
+SQLITE_PRIVATE LogEst sqlite3LogEst(u64 x){
+  static LogEst a[] = { 0, 2, 3, 5, 6, 7, 8, 9 };
+  LogEst y = 40;
+  if( x<8 ){
+    if( x<2 ) return 0;
+    while( x<8 ){  y -= 10; x <<= 1; }
+  }else{
+    while( x>255 ){ y += 40; x >>= 4; }  /*OPTIMIZATION-IF-TRUE*/
+    while( x>15 ){  y += 10; x >>= 1; }
+  }
+  return a[x&7] + y - 10;
+}
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/*
+** Convert a double into a LogEst
+** In other words, compute an approximation for 10*log2(x).
+*/
+SQLITE_PRIVATE LogEst sqlite3LogEstFromDouble(double x){
+  u64 a;
+  LogEst e;
+  assert( sizeof(x)==8 && sizeof(a)==8 );
+  if( x<=1 ) return 0;
+  if( x<=2000000000 ) return sqlite3LogEst((u64)x);
+  memcpy(&a, &x, 8);
+  e = (a>>52) - 1022;
+  return e*10;
+}
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+#if defined(SQLITE_ENABLE_STMT_SCANSTATUS) || \
+    defined(SQLITE_ENABLE_STAT3_OR_STAT4) || \
+    defined(SQLITE_EXPLAIN_ESTIMATED_ROWS)
+/*
+** Convert a LogEst into an integer.
+**
+** Note that this routine is only used when one or more of various
+** non-standard compile-time options is enabled.
+*/
+SQLITE_PRIVATE u64 sqlite3LogEstToInt(LogEst x){
+  u64 n;
+  n = x%10;
+  x /= 10;
+  if( n>=5 ) n -= 2;
+  else if( n>=1 ) n -= 1;
+#if defined(SQLITE_ENABLE_STMT_SCANSTATUS) || \
+    defined(SQLITE_EXPLAIN_ESTIMATED_ROWS)
+  if( x>60 ) return (u64)LARGEST_INT64;
+#else
+  /* If only SQLITE_ENABLE_STAT3_OR_STAT4 is on, then the largest input
+  ** possible to this routine is 310, resulting in a maximum x of 31 */
+  assert( x<=60 );
+#endif
+  return x>=3 ? (n+8)<<(x-3) : (n+8)>>(3-x);
+}
+#endif /* defined SCANSTAT or STAT4 or ESTIMATED_ROWS */
+
+/************** End of util.c ************************************************/
+/************** Begin file hash.c ********************************************/
+/*
+** 2001 September 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This is the implementation of generic hash-tables
+** used in SQLite.
+*/
+/* #include "sqliteInt.h" */
+/* #include <assert.h> */
+
+/* Turn bulk memory into a hash table object by initializing the
+** fields of the Hash structure.
+**
+** "pNew" is a pointer to the hash table that is to be initialized.
+*/
+SQLITE_PRIVATE void sqlite3HashInit(Hash *pNew){
+  assert( pNew!=0 );
+  pNew->first = 0;
+  pNew->count = 0;
+  pNew->htsize = 0;
+  pNew->ht = 0;
+}
+
+/* Remove all entries from a hash table.  Reclaim all memory.
+** Call this routine to delete a hash table or to reset a hash table
+** to the empty state.
+*/
+SQLITE_PRIVATE void sqlite3HashClear(Hash *pH){
+  HashElem *elem;         /* For looping over all elements of the table */
+
+  assert( pH!=0 );
+  elem = pH->first;
+  pH->first = 0;
+  sqlite3_free(pH->ht);
+  pH->ht = 0;
+  pH->htsize = 0;
+  while( elem ){
+    HashElem *next_elem = elem->next;
+    sqlite3_free(elem);
+    elem = next_elem;
+  }
+  pH->count = 0;
+}
+
+/*
+** The hashing function.
+*/
+static unsigned int strHash(const char *z){
+  unsigned int h = 0;
+  unsigned char c;
+  while( (c = (unsigned char)*z++)!=0 ){     /*OPTIMIZATION-IF-TRUE*/
+    /* Knuth multiplicative hashing.  (Sorting & Searching, p. 510).
+    ** 0x9e3779b1 is 2654435761 which is the closest prime number to
+    ** (2**32)*golden_ratio, where golden_ratio = (sqrt(5) - 1)/2. */
+    h += sqlite3UpperToLower[c];
+    h *= 0x9e3779b1;
+  }
+  return h;
+}
+
+
+/* Link pNew element into the hash table pH.  If pEntry!=0 then also
+** insert pNew into the pEntry hash bucket.
+*/
+static void insertElement(
+  Hash *pH,              /* The complete hash table */
+  struct _ht *pEntry,    /* The entry into which pNew is inserted */
+  HashElem *pNew         /* The element to be inserted */
+){
+  HashElem *pHead;       /* First element already in pEntry */
+  if( pEntry ){
+    pHead = pEntry->count ? pEntry->chain : 0;
+    pEntry->count++;
+    pEntry->chain = pNew;
+  }else{
+    pHead = 0;
+  }
+  if( pHead ){
+    pNew->next = pHead;
+    pNew->prev = pHead->prev;
+    if( pHead->prev ){ pHead->prev->next = pNew; }
+    else             { pH->first = pNew; }
+    pHead->prev = pNew;
+  }else{
+    pNew->next = pH->first;
+    if( pH->first ){ pH->first->prev = pNew; }
+    pNew->prev = 0;
+    pH->first = pNew;
+  }
+}
+
+
+/* Resize the hash table so that it cantains "new_size" buckets.
+**
+** The hash table might fail to resize if sqlite3_malloc() fails or
+** if the new size is the same as the prior size.
+** Return TRUE if the resize occurs and false if not.
+*/
+static int rehash(Hash *pH, unsigned int new_size){
+  struct _ht *new_ht;            /* The new hash table */
+  HashElem *elem, *next_elem;    /* For looping over existing elements */
+
+#if SQLITE_MALLOC_SOFT_LIMIT>0
+  if( new_size*sizeof(struct _ht)>SQLITE_MALLOC_SOFT_LIMIT ){
+    new_size = SQLITE_MALLOC_SOFT_LIMIT/sizeof(struct _ht);
+  }
+  if( new_size==pH->htsize ) return 0;
+#endif
+
+  /* The inability to allocates space for a larger hash table is
+  ** a performance hit but it is not a fatal error.  So mark the
+  ** allocation as a benign. Use sqlite3Malloc()/memset(0) instead of 
+  ** sqlite3MallocZero() to make the allocation, as sqlite3MallocZero()
+  ** only zeroes the requested number of bytes whereas this module will
+  ** use the actual amount of space allocated for the hash table (which
+  ** may be larger than the requested amount).
+  */
+  sqlite3BeginBenignMalloc();
+  new_ht = (struct _ht *)sqlite3Malloc( new_size*sizeof(struct _ht) );
+  sqlite3EndBenignMalloc();
+
+  if( new_ht==0 ) return 0;
+  sqlite3_free(pH->ht);
+  pH->ht = new_ht;
+  pH->htsize = new_size = sqlite3MallocSize(new_ht)/sizeof(struct _ht);
+  memset(new_ht, 0, new_size*sizeof(struct _ht));
+  for(elem=pH->first, pH->first=0; elem; elem = next_elem){
+    unsigned int h = strHash(elem->pKey) % new_size;
+    next_elem = elem->next;
+    insertElement(pH, &new_ht[h], elem);
+  }
+  return 1;
+}
+
+/* This function (for internal use only) locates an element in an
+** hash table that matches the given key.  The hash for this key is
+** also computed and returned in the *pH parameter.
+*/
+static HashElem *findElementWithHash(
+  const Hash *pH,     /* The pH to be searched */
+  const char *pKey,   /* The key we are searching for */
+  unsigned int *pHash /* Write the hash value here */
+){
+  HashElem *elem;                /* Used to loop thru the element list */
+  int count;                     /* Number of elements left to test */
+  unsigned int h;                /* The computed hash */
+
+  if( pH->ht ){   /*OPTIMIZATION-IF-TRUE*/
+    struct _ht *pEntry;
+    h = strHash(pKey) % pH->htsize;
+    pEntry = &pH->ht[h];
+    elem = pEntry->chain;
+    count = pEntry->count;
+  }else{
+    h = 0;
+    elem = pH->first;
+    count = pH->count;
+  }
+  *pHash = h;
+  while( count-- ){
+    assert( elem!=0 );
+    if( sqlite3StrICmp(elem->pKey,pKey)==0 ){ 
+      return elem;
+    }
+    elem = elem->next;
+  }
+  return 0;
+}
+
+/* Remove a single entry from the hash table given a pointer to that
+** element and a hash on the element's key.
+*/
+static void removeElementGivenHash(
+  Hash *pH,         /* The pH containing "elem" */
+  HashElem* elem,   /* The element to be removed from the pH */
+  unsigned int h    /* Hash value for the element */
+){
+  struct _ht *pEntry;
+  if( elem->prev ){
+    elem->prev->next = elem->next; 
+  }else{
+    pH->first = elem->next;
+  }
+  if( elem->next ){
+    elem->next->prev = elem->prev;
+  }
+  if( pH->ht ){
+    pEntry = &pH->ht[h];
+    if( pEntry->chain==elem ){
+      pEntry->chain = elem->next;
+    }
+    pEntry->count--;
+    assert( pEntry->count>=0 );
+  }
+  sqlite3_free( elem );
+  pH->count--;
+  if( pH->count==0 ){
+    assert( pH->first==0 );
+    assert( pH->count==0 );
+    sqlite3HashClear(pH);
+  }
+}
+
+/* Attempt to locate an element of the hash table pH with a key
+** that matches pKey.  Return the data for this element if it is
+** found, or NULL if there is no match.
+*/
+SQLITE_PRIVATE void *sqlite3HashFind(const Hash *pH, const char *pKey){
+  HashElem *elem;    /* The element that matches key */
+  unsigned int h;    /* A hash on key */
+
+  assert( pH!=0 );
+  assert( pKey!=0 );
+  elem = findElementWithHash(pH, pKey, &h);
+  return elem ? elem->data : 0;
+}
+
+/* Insert an element into the hash table pH.  The key is pKey
+** and the data is "data".
+**
+** If no element exists with a matching key, then a new
+** element is created and NULL is returned.
+**
+** If another element already exists with the same key, then the
+** new data replaces the old data and the old data is returned.
+** The key is not copied in this instance.  If a malloc fails, then
+** the new data is returned and the hash table is unchanged.
+**
+** If the "data" parameter to this function is NULL, then the
+** element corresponding to "key" is removed from the hash table.
+*/
+SQLITE_PRIVATE void *sqlite3HashInsert(Hash *pH, const char *pKey, void *data){
+  unsigned int h;       /* the hash of the key modulo hash table size */
+  HashElem *elem;       /* Used to loop thru the element list */
+  HashElem *new_elem;   /* New element added to the pH */
+
+  assert( pH!=0 );
+  assert( pKey!=0 );
+  elem = findElementWithHash(pH,pKey,&h);
+  if( elem ){
+    void *old_data = elem->data;
+    if( data==0 ){
+      removeElementGivenHash(pH,elem,h);
+    }else{
+      elem->data = data;
+      elem->pKey = pKey;
+    }
+    return old_data;
+  }
+  if( data==0 ) return 0;
+  new_elem = (HashElem*)sqlite3Malloc( sizeof(HashElem) );
+  if( new_elem==0 ) return data;
+  new_elem->pKey = pKey;
+  new_elem->data = data;
+  pH->count++;
+  if( pH->count>=10 && pH->count > 2*pH->htsize ){
+    if( rehash(pH, pH->count*2) ){
+      assert( pH->htsize>0 );
+      h = strHash(pKey) % pH->htsize;
+    }
+  }
+  insertElement(pH, pH->ht ? &pH->ht[h] : 0, new_elem);
+  return 0;
+}
+
+/************** End of hash.c ************************************************/
+/************** Begin file opcodes.c *****************************************/
+/* Automatically generated.  Do not edit */
+/* See the tool/mkopcodec.tcl script for details. */
+#if !defined(SQLITE_OMIT_EXPLAIN) \
+ || defined(VDBE_PROFILE) \
+ || defined(SQLITE_DEBUG)
+#if defined(SQLITE_ENABLE_EXPLAIN_COMMENTS) || defined(SQLITE_DEBUG)
+# define OpHelp(X) "\0" X
+#else
+# define OpHelp(X)
+#endif
+SQLITE_PRIVATE const char *sqlite3OpcodeName(int i){
+ static const char *const azName[] = {
+    /*   0 */ "Savepoint"        OpHelp(""),
+    /*   1 */ "AutoCommit"       OpHelp(""),
+    /*   2 */ "Transaction"      OpHelp(""),
+    /*   3 */ "SorterNext"       OpHelp(""),
+    /*   4 */ "PrevIfOpen"       OpHelp(""),
+    /*   5 */ "NextIfOpen"       OpHelp(""),
+    /*   6 */ "Prev"             OpHelp(""),
+    /*   7 */ "Next"             OpHelp(""),
+    /*   8 */ "Checkpoint"       OpHelp(""),
+    /*   9 */ "JournalMode"      OpHelp(""),
+    /*  10 */ "Vacuum"           OpHelp(""),
+    /*  11 */ "VFilter"          OpHelp("iplan=r[P3] zplan='P4'"),
+    /*  12 */ "VUpdate"          OpHelp("data=r[P3@P2]"),
+    /*  13 */ "Goto"             OpHelp(""),
+    /*  14 */ "Gosub"            OpHelp(""),
+    /*  15 */ "InitCoroutine"    OpHelp(""),
+    /*  16 */ "Yield"            OpHelp(""),
+    /*  17 */ "MustBeInt"        OpHelp(""),
+    /*  18 */ "Jump"             OpHelp(""),
+    /*  19 */ "Not"              OpHelp("r[P2]= !r[P1]"),
+    /*  20 */ "Once"             OpHelp(""),
+    /*  21 */ "If"               OpHelp(""),
+    /*  22 */ "IfNot"            OpHelp(""),
+    /*  23 */ "SeekLT"           OpHelp("key=r[P3@P4]"),
+    /*  24 */ "SeekLE"           OpHelp("key=r[P3@P4]"),
+    /*  25 */ "SeekGE"           OpHelp("key=r[P3@P4]"),
+    /*  26 */ "SeekGT"           OpHelp("key=r[P3@P4]"),
+    /*  27 */ "Or"               OpHelp("r[P3]=(r[P1] || r[P2])"),
+    /*  28 */ "And"              OpHelp("r[P3]=(r[P1] && r[P2])"),
+    /*  29 */ "NoConflict"       OpHelp("key=r[P3@P4]"),
+    /*  30 */ "NotFound"         OpHelp("key=r[P3@P4]"),
+    /*  31 */ "Found"            OpHelp("key=r[P3@P4]"),
+    /*  32 */ "SeekRowid"        OpHelp("intkey=r[P3]"),
+    /*  33 */ "NotExists"        OpHelp("intkey=r[P3]"),
+    /*  34 */ "IsNull"           OpHelp("if r[P1]==NULL goto P2"),
+    /*  35 */ "NotNull"          OpHelp("if r[P1]!=NULL goto P2"),
+    /*  36 */ "Ne"               OpHelp("IF r[P3]!=r[P1]"),
+    /*  37 */ "Eq"               OpHelp("IF r[P3]==r[P1]"),
+    /*  38 */ "Gt"               OpHelp("IF r[P3]>r[P1]"),
+    /*  39 */ "Le"               OpHelp("IF r[P3]<=r[P1]"),
+    /*  40 */ "Lt"               OpHelp("IF r[P3]<r[P1]"),
+    /*  41 */ "Ge"               OpHelp("IF r[P3]>=r[P1]"),
+    /*  42 */ "ElseNotEq"        OpHelp(""),
+    /*  43 */ "BitAnd"           OpHelp("r[P3]=r[P1]&r[P2]"),
+    /*  44 */ "BitOr"            OpHelp("r[P3]=r[P1]|r[P2]"),
+    /*  45 */ "ShiftLeft"        OpHelp("r[P3]=r[P2]<<r[P1]"),
+    /*  46 */ "ShiftRight"       OpHelp("r[P3]=r[P2]>>r[P1]"),
+    /*  47 */ "Add"              OpHelp("r[P3]=r[P1]+r[P2]"),
+    /*  48 */ "Subtract"         OpHelp("r[P3]=r[P2]-r[P1]"),
+    /*  49 */ "Multiply"         OpHelp("r[P3]=r[P1]*r[P2]"),
+    /*  50 */ "Divide"           OpHelp("r[P3]=r[P2]/r[P1]"),
+    /*  51 */ "Remainder"        OpHelp("r[P3]=r[P2]%r[P1]"),
+    /*  52 */ "Concat"           OpHelp("r[P3]=r[P2]+r[P1]"),
+    /*  53 */ "Last"             OpHelp(""),
+    /*  54 */ "BitNot"           OpHelp("r[P1]= ~r[P1]"),
+    /*  55 */ "SorterSort"       OpHelp(""),
+    /*  56 */ "Sort"             OpHelp(""),
+    /*  57 */ "Rewind"           OpHelp(""),
+    /*  58 */ "IdxLE"            OpHelp("key=r[P3@P4]"),
+    /*  59 */ "IdxGT"            OpHelp("key=r[P3@P4]"),
+    /*  60 */ "IdxLT"            OpHelp("key=r[P3@P4]"),
+    /*  61 */ "IdxGE"            OpHelp("key=r[P3@P4]"),
+    /*  62 */ "RowSetRead"       OpHelp("r[P3]=rowset(P1)"),
+    /*  63 */ "RowSetTest"       OpHelp("if r[P3] in rowset(P1) goto P2"),
+    /*  64 */ "Program"          OpHelp(""),
+    /*  65 */ "FkIfZero"         OpHelp("if fkctr[P1]==0 goto P2"),
+    /*  66 */ "IfPos"            OpHelp("if r[P1]>0 then r[P1]-=P3, goto P2"),
+    /*  67 */ "IfNotZero"        OpHelp("if r[P1]!=0 then r[P1]-=P3, goto P2"),
+    /*  68 */ "DecrJumpZero"     OpHelp("if (--r[P1])==0 goto P2"),
+    /*  69 */ "IncrVacuum"       OpHelp(""),
+    /*  70 */ "VNext"            OpHelp(""),
+    /*  71 */ "Init"             OpHelp("Start at P2"),
+    /*  72 */ "Return"           OpHelp(""),
+    /*  73 */ "EndCoroutine"     OpHelp(""),
+    /*  74 */ "HaltIfNull"       OpHelp("if r[P3]=null halt"),
+    /*  75 */ "Halt"             OpHelp(""),
+    /*  76 */ "Integer"          OpHelp("r[P2]=P1"),
+    /*  77 */ "Int64"            OpHelp("r[P2]=P4"),
+    /*  78 */ "String"           OpHelp("r[P2]='P4' (len=P1)"),
+    /*  79 */ "Null"             OpHelp("r[P2..P3]=NULL"),
+    /*  80 */ "SoftNull"         OpHelp("r[P1]=NULL"),
+    /*  81 */ "Blob"             OpHelp("r[P2]=P4 (len=P1)"),
+    /*  82 */ "Variable"         OpHelp("r[P2]=parameter(P1,P4)"),
+    /*  83 */ "Move"             OpHelp("r[P2@P3]=r[P1@P3]"),
+    /*  84 */ "Copy"             OpHelp("r[P2@P3+1]=r[P1@P3+1]"),
+    /*  85 */ "SCopy"            OpHelp("r[P2]=r[P1]"),
+    /*  86 */ "IntCopy"          OpHelp("r[P2]=r[P1]"),
+    /*  87 */ "ResultRow"        OpHelp("output=r[P1@P2]"),
+    /*  88 */ "CollSeq"          OpHelp(""),
+    /*  89 */ "Function0"        OpHelp("r[P3]=func(r[P2@P5])"),
+    /*  90 */ "Function"         OpHelp("r[P3]=func(r[P2@P5])"),
+    /*  91 */ "AddImm"           OpHelp("r[P1]=r[P1]+P2"),
+    /*  92 */ "RealAffinity"     OpHelp(""),
+    /*  93 */ "Cast"             OpHelp("affinity(r[P1])"),
+    /*  94 */ "Permutation"      OpHelp(""),
+    /*  95 */ "Compare"          OpHelp("r[P1@P3] <-> r[P2@P3]"),
+    /*  96 */ "Column"           OpHelp("r[P3]=PX"),
+    /*  97 */ "String8"          OpHelp("r[P2]='P4'"),
+    /*  98 */ "Affinity"         OpHelp("affinity(r[P1@P2])"),
+    /*  99 */ "MakeRecord"       OpHelp("r[P3]=mkrec(r[P1@P2])"),
+    /* 100 */ "Count"            OpHelp("r[P2]=count()"),
+    /* 101 */ "ReadCookie"       OpHelp(""),
+    /* 102 */ "SetCookie"        OpHelp(""),
+    /* 103 */ "ReopenIdx"        OpHelp("root=P2 iDb=P3"),
+    /* 104 */ "OpenRead"         OpHelp("root=P2 iDb=P3"),
+    /* 105 */ "OpenWrite"        OpHelp("root=P2 iDb=P3"),
+    /* 106 */ "OpenAutoindex"    OpHelp("nColumn=P2"),
+    /* 107 */ "OpenEphemeral"    OpHelp("nColumn=P2"),
+    /* 108 */ "SorterOpen"       OpHelp(""),
+    /* 109 */ "SequenceTest"     OpHelp("if( cursor[P1].ctr++ ) pc = P2"),
+    /* 110 */ "OpenPseudo"       OpHelp("P3 columns in r[P2]"),
+    /* 111 */ "Close"            OpHelp(""),
+    /* 112 */ "ColumnsUsed"      OpHelp(""),
+    /* 113 */ "Sequence"         OpHelp("r[P2]=cursor[P1].ctr++"),
+    /* 114 */ "NewRowid"         OpHelp("r[P2]=rowid"),
+    /* 115 */ "Insert"           OpHelp("intkey=r[P3] data=r[P2]"),
+    /* 116 */ "InsertInt"        OpHelp("intkey=P3 data=r[P2]"),
+    /* 117 */ "Delete"           OpHelp(""),
+    /* 118 */ "ResetCount"       OpHelp(""),
+    /* 119 */ "SorterCompare"    OpHelp("if key(P1)!=trim(r[P3],P4) goto P2"),
+    /* 120 */ "SorterData"       OpHelp("r[P2]=data"),
+    /* 121 */ "RowKey"           OpHelp("r[P2]=key"),
+    /* 122 */ "RowData"          OpHelp("r[P2]=data"),
+    /* 123 */ "Rowid"            OpHelp("r[P2]=rowid"),
+    /* 124 */ "NullRow"          OpHelp(""),
+    /* 125 */ "SorterInsert"     OpHelp(""),
+    /* 126 */ "IdxInsert"        OpHelp("key=r[P2]"),
+    /* 127 */ "IdxDelete"        OpHelp("key=r[P2@P3]"),
+    /* 128 */ "Seek"             OpHelp("Move P3 to P1.rowid"),
+    /* 129 */ "IdxRowid"         OpHelp("r[P2]=rowid"),
+    /* 130 */ "Destroy"          OpHelp(""),
+    /* 131 */ "Clear"            OpHelp(""),
+    /* 132 */ "Real"             OpHelp("r[P2]=P4"),
+    /* 133 */ "ResetSorter"      OpHelp(""),
+    /* 134 */ "CreateIndex"      OpHelp("r[P2]=root iDb=P1"),
+    /* 135 */ "CreateTable"      OpHelp("r[P2]=root iDb=P1"),
+    /* 136 */ "ParseSchema"      OpHelp(""),
+    /* 137 */ "LoadAnalysis"     OpHelp(""),
+    /* 138 */ "DropTable"        OpHelp(""),
+    /* 139 */ "DropIndex"        OpHelp(""),
+    /* 140 */ "DropTrigger"      OpHelp(""),
+    /* 141 */ "IntegrityCk"      OpHelp(""),
+    /* 142 */ "RowSetAdd"        OpHelp("rowset(P1)=r[P2]"),
+    /* 143 */ "Param"            OpHelp(""),
+    /* 144 */ "FkCounter"        OpHelp("fkctr[P1]+=P2"),
+    /* 145 */ "MemMax"           OpHelp("r[P1]=max(r[P1],r[P2])"),
+    /* 146 */ "OffsetLimit"      OpHelp("if r[P1]>0 then r[P2]=r[P1]+max(0,r[P3]) else r[P2]=(-1)"),
+    /* 147 */ "AggStep0"         OpHelp("accum=r[P3] step(r[P2@P5])"),
+    /* 148 */ "AggStep"          OpHelp("accum=r[P3] step(r[P2@P5])"),
+    /* 149 */ "AggFinal"         OpHelp("accum=r[P1] N=P2"),
+    /* 150 */ "Expire"           OpHelp(""),
+    /* 151 */ "TableLock"        OpHelp("iDb=P1 root=P2 write=P3"),
+    /* 152 */ "VBegin"           OpHelp(""),
+    /* 153 */ "VCreate"          OpHelp(""),
+    /* 154 */ "VDestroy"         OpHelp(""),
+    /* 155 */ "VOpen"            OpHelp(""),
+    /* 156 */ "VColumn"          OpHelp("r[P3]=vcolumn(P2)"),
+    /* 157 */ "VRename"          OpHelp(""),
+    /* 158 */ "Pagecount"        OpHelp(""),
+    /* 159 */ "MaxPgcnt"         OpHelp(""),
+    /* 160 */ "CursorHint"       OpHelp(""),
+    /* 161 */ "Noop"             OpHelp(""),
+    /* 162 */ "Explain"          OpHelp(""),
+  };
+  return azName[i];
+}
+#endif
+
+/************** End of opcodes.c *********************************************/
+/************** Begin file os_unix.c *****************************************/
+/*
+** 2004 May 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains the VFS implementation for unix-like operating systems
+** include Linux, MacOSX, *BSD, QNX, VxWorks, AIX, HPUX, and others.
+**
+** There are actually several different VFS implementations in this file.
+** The differences are in the way that file locking is done.  The default
+** implementation uses Posix Advisory Locks.  Alternative implementations
+** use flock(), dot-files, various proprietary locking schemas, or simply
+** skip locking all together.
+**
+** This source file is organized into divisions where the logic for various
+** subfunctions is contained within the appropriate division.  PLEASE
+** KEEP THE STRUCTURE OF THIS FILE INTACT.  New code should be placed
+** in the correct division and should be clearly labeled.
+**
+** The layout of divisions is as follows:
+**
+**   *  General-purpose declarations and utility functions.
+**   *  Unique file ID logic used by VxWorks.
+**   *  Various locking primitive implementations (all except proxy locking):
+**      + for Posix Advisory Locks
+**      + for no-op locks
+**      + for dot-file locks
+**      + for flock() locking
+**      + for named semaphore locks (VxWorks only)
+**      + for AFP filesystem locks (MacOSX only)
+**   *  sqlite3_file methods not associated with locking.
+**   *  Definitions of sqlite3_io_methods objects for all locking
+**      methods plus "finder" functions for each locking method.
+**   *  sqlite3_vfs method implementations.
+**   *  Locking primitives for the proxy uber-locking-method. (MacOSX only)
+**   *  Definitions of sqlite3_vfs objects for all locking methods
+**      plus implementations of sqlite3_os_init() and sqlite3_os_end().
+*/
+/* #include "sqliteInt.h" */
+#if SQLITE_OS_UNIX              /* This file is used on unix only */
+
+/*
+** There are various methods for file locking used for concurrency
+** control:
+**
+**   1. POSIX locking (the default),
+**   2. No locking,
+**   3. Dot-file locking,
+**   4. flock() locking,
+**   5. AFP locking (OSX only),
+**   6. Named POSIX semaphores (VXWorks only),
+**   7. proxy locking. (OSX only)
+**
+** Styles 4, 5, and 7 are only available of SQLITE_ENABLE_LOCKING_STYLE
+** is defined to 1.  The SQLITE_ENABLE_LOCKING_STYLE also enables automatic
+** selection of the appropriate locking style based on the filesystem
+** where the database is located.  
+*/
+#if !defined(SQLITE_ENABLE_LOCKING_STYLE)
+#  if defined(__APPLE__)
+#    define SQLITE_ENABLE_LOCKING_STYLE 1
+#  else
+#    define SQLITE_ENABLE_LOCKING_STYLE 0
+#  endif
+#endif
+
+/* Use pread() and pwrite() if they are available */
+#if defined(__APPLE__)
+# define HAVE_PREAD 1
+# define HAVE_PWRITE 1
+#endif
+#if defined(HAVE_PREAD64) && defined(HAVE_PWRITE64)
+# undef USE_PREAD
+# define USE_PREAD64 1
+#elif defined(HAVE_PREAD) && defined(HAVE_PWRITE)
+# undef USE_PREAD64
+# define USE_PREAD 1
+#endif
+
+/*
+** standard include files.
+*/
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+/* #include <time.h> */
+#include <sys/time.h>
+#include <errno.h>
+#if !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0
+/* # include <sys/mman.h> */
+#endif
+
+#if SQLITE_ENABLE_LOCKING_STYLE
+# include <sys/ioctl.h>
+# include <sys/file.h>
+# include <sys/param.h>
+#endif /* SQLITE_ENABLE_LOCKING_STYLE */
+
+#if defined(__APPLE__) && ((__MAC_OS_X_VERSION_MIN_REQUIRED > 1050) || \
+                           (__IPHONE_OS_VERSION_MIN_REQUIRED > 2000))
+#  if (!defined(TARGET_OS_EMBEDDED) || (TARGET_OS_EMBEDDED==0)) \
+       && (!defined(TARGET_IPHONE_SIMULATOR) || (TARGET_IPHONE_SIMULATOR==0))
+#    define HAVE_GETHOSTUUID 1
+#  else
+#    warning "gethostuuid() is disabled."
+#  endif
+#endif
+
+
+#if OS_VXWORKS
+/* # include <sys/ioctl.h> */
+# include <semaphore.h>
+# include <limits.h>
+#endif /* OS_VXWORKS */
+
+#if defined(__APPLE__) || SQLITE_ENABLE_LOCKING_STYLE
+# include <sys/mount.h>
+#endif
+
+#ifdef HAVE_UTIME
+# include <utime.h>
+#endif
+
+/*
+** Allowed values of unixFile.fsFlags
+*/
+#define SQLITE_FSFLAGS_IS_MSDOS     0x1
+
+/*
+** If we are to be thread-safe, include the pthreads header and define
+** the SQLITE_UNIX_THREADS macro.
+*/
+#if SQLITE_THREADSAFE
+/* # include <pthread.h> */
+# define SQLITE_UNIX_THREADS 1
+#endif
+
+/*
+** Default permissions when creating a new file
+*/
+#ifndef SQLITE_DEFAULT_FILE_PERMISSIONS
+# define SQLITE_DEFAULT_FILE_PERMISSIONS 0644
+#endif
+
+/*
+** Default permissions when creating auto proxy dir
+*/
+#ifndef SQLITE_DEFAULT_PROXYDIR_PERMISSIONS
+# define SQLITE_DEFAULT_PROXYDIR_PERMISSIONS 0755
+#endif
+
+/*
+** Maximum supported path-length.
+*/
+#define MAX_PATHNAME 512
+
+/*
+** Maximum supported symbolic links
+*/
+#define SQLITE_MAX_SYMLINKS 100
+
+/* Always cast the getpid() return type for compatibility with
+** kernel modules in VxWorks. */
+#define osGetpid(X) (pid_t)getpid()
+
+/*
+** Only set the lastErrno if the error code is a real error and not 
+** a normal expected return code of SQLITE_BUSY or SQLITE_OK
+*/
+#define IS_LOCK_ERROR(x)  ((x != SQLITE_OK) && (x != SQLITE_BUSY))
+
+/* Forward references */
+typedef struct unixShm unixShm;               /* Connection shared memory */
+typedef struct unixShmNode unixShmNode;       /* Shared memory instance */
+typedef struct unixInodeInfo unixInodeInfo;   /* An i-node */
+typedef struct UnixUnusedFd UnixUnusedFd;     /* An unused file descriptor */
+
+/*
+** Sometimes, after a file handle is closed by SQLite, the file descriptor
+** cannot be closed immediately. In these cases, instances of the following
+** structure are used to store the file descriptor while waiting for an
+** opportunity to either close or reuse it.
+*/
+struct UnixUnusedFd {
+  int fd;                   /* File descriptor to close */
+  int flags;                /* Flags this file descriptor was opened with */
+  UnixUnusedFd *pNext;      /* Next unused file descriptor on same file */
+};
+
+/*
+** The unixFile structure is subclass of sqlite3_file specific to the unix
+** VFS implementations.
+*/
+typedef struct unixFile unixFile;
+struct unixFile {
+  sqlite3_io_methods const *pMethod;  /* Always the first entry */
+  sqlite3_vfs *pVfs;                  /* The VFS that created this unixFile */
+  unixInodeInfo *pInode;              /* Info about locks on this inode */
+  int h;                              /* The file descriptor */
+  unsigned char eFileLock;            /* The type of lock held on this fd */
+  unsigned short int ctrlFlags;       /* Behavioral bits.  UNIXFILE_* flags */
+  int lastErrno;                      /* The unix errno from last I/O error */
+  void *lockingContext;               /* Locking style specific state */
+  UnixUnusedFd *pUnused;              /* Pre-allocated UnixUnusedFd */
+  const char *zPath;                  /* Name of the file */
+  unixShm *pShm;                      /* Shared memory segment information */
+  int szChunk;                        /* Configured by FCNTL_CHUNK_SIZE */
+#if SQLITE_MAX_MMAP_SIZE>0
+  int nFetchOut;                      /* Number of outstanding xFetch refs */
+  sqlite3_int64 mmapSize;             /* Usable size of mapping at pMapRegion */
+  sqlite3_int64 mmapSizeActual;       /* Actual size of mapping at pMapRegion */
+  sqlite3_int64 mmapSizeMax;          /* Configured FCNTL_MMAP_SIZE value */
+  void *pMapRegion;                   /* Memory mapped region */
+#endif
+#ifdef __QNXNTO__
+  int sectorSize;                     /* Device sector size */
+  int deviceCharacteristics;          /* Precomputed device characteristics */
+#endif
+#if SQLITE_ENABLE_LOCKING_STYLE
+  int openFlags;                      /* The flags specified at open() */
+#endif
+#if SQLITE_ENABLE_LOCKING_STYLE || defined(__APPLE__)
+  unsigned fsFlags;                   /* cached details from statfs() */
+#endif
+#if OS_VXWORKS
+  struct vxworksFileId *pId;          /* Unique file ID */
+#endif
+#ifdef SQLITE_DEBUG
+  /* The next group of variables are used to track whether or not the
+  ** transaction counter in bytes 24-27 of database files are updated
+  ** whenever any part of the database changes.  An assertion fault will
+  ** occur if a file is updated without also updating the transaction
+  ** counter.  This test is made to avoid new problems similar to the
+  ** one described by ticket #3584. 
+  */
+  unsigned char transCntrChng;   /* True if the transaction counter changed */
+  unsigned char dbUpdate;        /* True if any part of database file changed */
+  unsigned char inNormalWrite;   /* True if in a normal write operation */
+
+#endif
+
+#ifdef SQLITE_TEST
+  /* In test mode, increase the size of this structure a bit so that 
+  ** it is larger than the struct CrashFile defined in test6.c.
+  */
+  char aPadding[32];
+#endif
+};
+
+/* This variable holds the process id (pid) from when the xRandomness()
+** method was called.  If xOpen() is called from a different process id,
+** indicating that a fork() has occurred, the PRNG will be reset.
+*/
+static pid_t randomnessPid = 0;
+
+/*
+** Allowed values for the unixFile.ctrlFlags bitmask:
+*/
+#define UNIXFILE_EXCL        0x01     /* Connections from one process only */
+#define UNIXFILE_RDONLY      0x02     /* Connection is read only */
+#define UNIXFILE_PERSIST_WAL 0x04     /* Persistent WAL mode */
+#ifndef SQLITE_DISABLE_DIRSYNC
+# define UNIXFILE_DIRSYNC    0x08     /* Directory sync needed */
+#else
+# define UNIXFILE_DIRSYNC    0x00
+#endif
+#define UNIXFILE_PSOW        0x10     /* SQLITE_IOCAP_POWERSAFE_OVERWRITE */
+#define UNIXFILE_DELETE      0x20     /* Delete on close */
+#define UNIXFILE_URI         0x40     /* Filename might have query parameters */
+#define UNIXFILE_NOLOCK      0x80     /* Do no file locking */
+
+/*
+** Include code that is common to all os_*.c files
+*/
+/************** Include os_common.h in the middle of os_unix.c ***************/
+/************** Begin file os_common.h ***************************************/
+/*
+** 2004 May 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains macros and a little bit of code that is common to
+** all of the platform-specific files (os_*.c) and is #included into those
+** files.
+**
+** This file should be #included by the os_*.c files only.  It is not a
+** general purpose header file.
+*/
+#ifndef _OS_COMMON_H_
+#define _OS_COMMON_H_
+
+/*
+** At least two bugs have slipped in because we changed the MEMORY_DEBUG
+** macro to SQLITE_DEBUG and some older makefiles have not yet made the
+** switch.  The following code should catch this problem at compile-time.
+*/
+#ifdef MEMORY_DEBUG
+# error "The MEMORY_DEBUG macro is obsolete.  Use SQLITE_DEBUG instead."
+#endif
+
+/*
+** Macros for performance tracing.  Normally turned off.  Only works
+** on i486 hardware.
+*/
+#ifdef SQLITE_PERFORMANCE_TRACE
+
+/*
+** hwtime.h contains inline assembler code for implementing
+** high-performance timing routines.
+*/
+/************** Include hwtime.h in the middle of os_common.h ****************/
+/************** Begin file hwtime.h ******************************************/
+/*
+** 2008 May 27
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains inline asm code for retrieving "high-performance"
+** counters for x86 class CPUs.
+*/
+#ifndef SQLITE_HWTIME_H
+#define SQLITE_HWTIME_H
+
+/*
+** The following routine only works on pentium-class (or newer) processors.
+** It uses the RDTSC opcode to read the cycle count value out of the
+** processor and returns that value.  This can be used for high-res
+** profiling.
+*/
+#if (defined(__GNUC__) || defined(_MSC_VER)) && \
+      (defined(i386) || defined(__i386__) || defined(_M_IX86))
+
+  #if defined(__GNUC__)
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+     unsigned int lo, hi;
+     __asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
+     return (sqlite_uint64)hi << 32 | lo;
+  }
+
+  #elif defined(_MSC_VER)
+
+  __declspec(naked) __inline sqlite_uint64 __cdecl sqlite3Hwtime(void){
+     __asm {
+        rdtsc
+        ret       ; return value at EDX:EAX
+     }
+  }
+
+  #endif
+
+#elif (defined(__GNUC__) && defined(__x86_64__))
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+      unsigned long val;
+      __asm__ __volatile__ ("rdtsc" : "=A" (val));
+      return val;
+  }
+ 
+#elif (defined(__GNUC__) && defined(__ppc__))
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+      unsigned long long retval;
+      unsigned long junk;
+      __asm__ __volatile__ ("\n\
+          1:      mftbu   %1\n\
+                  mftb    %L0\n\
+                  mftbu   %0\n\
+                  cmpw    %0,%1\n\
+                  bne     1b"
+                  : "=r" (retval), "=r" (junk));
+      return retval;
+  }
+
+#else
+
+  #error Need implementation of sqlite3Hwtime() for your platform.
+
+  /*
+  ** To compile without implementing sqlite3Hwtime() for your platform,
+  ** you can remove the above #error and use the following
+  ** stub function.  You will lose timing support for many
+  ** of the debugging and testing utilities, but it should at
+  ** least compile and run.
+  */
+SQLITE_PRIVATE   sqlite_uint64 sqlite3Hwtime(void){ return ((sqlite_uint64)0); }
+
+#endif
+
+#endif /* !defined(SQLITE_HWTIME_H) */
+
+/************** End of hwtime.h **********************************************/
+/************** Continuing where we left off in os_common.h ******************/
+
+static sqlite_uint64 g_start;
+static sqlite_uint64 g_elapsed;
+#define TIMER_START       g_start=sqlite3Hwtime()
+#define TIMER_END         g_elapsed=sqlite3Hwtime()-g_start
+#define TIMER_ELAPSED     g_elapsed
+#else
+#define TIMER_START
+#define TIMER_END
+#define TIMER_ELAPSED     ((sqlite_uint64)0)
+#endif
+
+/*
+** If we compile with the SQLITE_TEST macro set, then the following block
+** of code will give us the ability to simulate a disk I/O error.  This
+** is used for testing the I/O recovery logic.
+*/
+#if defined(SQLITE_TEST)
+SQLITE_API extern int sqlite3_io_error_hit;
+SQLITE_API extern int sqlite3_io_error_hardhit;
+SQLITE_API extern int sqlite3_io_error_pending;
+SQLITE_API extern int sqlite3_io_error_persist;
+SQLITE_API extern int sqlite3_io_error_benign;
+SQLITE_API extern int sqlite3_diskfull_pending;
+SQLITE_API extern int sqlite3_diskfull;
+#define SimulateIOErrorBenign(X) sqlite3_io_error_benign=(X)
+#define SimulateIOError(CODE)  \
+  if( (sqlite3_io_error_persist && sqlite3_io_error_hit) \
+       || sqlite3_io_error_pending-- == 1 )  \
+              { local_ioerr(); CODE; }
+static void local_ioerr(){
+  IOTRACE(("IOERR\n"));
+  sqlite3_io_error_hit++;
+  if( !sqlite3_io_error_benign ) sqlite3_io_error_hardhit++;
+}
+#define SimulateDiskfullError(CODE) \
+   if( sqlite3_diskfull_pending ){ \
+     if( sqlite3_diskfull_pending == 1 ){ \
+       local_ioerr(); \
+       sqlite3_diskfull = 1; \
+       sqlite3_io_error_hit = 1; \
+       CODE; \
+     }else{ \
+       sqlite3_diskfull_pending--; \
+     } \
+   }
+#else
+#define SimulateIOErrorBenign(X)
+#define SimulateIOError(A)
+#define SimulateDiskfullError(A)
+#endif /* defined(SQLITE_TEST) */
+
+/*
+** When testing, keep a count of the number of open files.
+*/
+#if defined(SQLITE_TEST)
+SQLITE_API extern int sqlite3_open_file_count;
+#define OpenCounter(X)  sqlite3_open_file_count+=(X)
+#else
+#define OpenCounter(X)
+#endif /* defined(SQLITE_TEST) */
+
+#endif /* !defined(_OS_COMMON_H_) */
+
+/************** End of os_common.h *******************************************/
+/************** Continuing where we left off in os_unix.c ********************/
+
+/*
+** Define various macros that are missing from some systems.
+*/
+#ifndef O_LARGEFILE
+# define O_LARGEFILE 0
+#endif
+#ifdef SQLITE_DISABLE_LFS
+# undef O_LARGEFILE
+# define O_LARGEFILE 0
+#endif
+#ifndef O_NOFOLLOW
+# define O_NOFOLLOW 0
+#endif
+#ifndef O_BINARY
+# define O_BINARY 0
+#endif
+
+/*
+** The threadid macro resolves to the thread-id or to 0.  Used for
+** testing and debugging only.
+*/
+#if SQLITE_THREADSAFE
+#define threadid pthread_self()
+#else
+#define threadid 0
+#endif
+
+/*
+** HAVE_MREMAP defaults to true on Linux and false everywhere else.
+*/
+#if !defined(HAVE_MREMAP)
+# if defined(__linux__) && defined(_GNU_SOURCE)
+#  define HAVE_MREMAP 1
+# else
+#  define HAVE_MREMAP 0
+# endif
+#endif
+
+/*
+** Explicitly call the 64-bit version of lseek() on Android. Otherwise, lseek()
+** is the 32-bit version, even if _FILE_OFFSET_BITS=64 is defined.
+*/
+#ifdef __ANDROID__
+# define lseek lseek64
+#endif
+
+/*
+** Different Unix systems declare open() in different ways.  Same use
+** open(const char*,int,mode_t).  Others use open(const char*,int,...).
+** The difference is important when using a pointer to the function.
+**
+** The safest way to deal with the problem is to always use this wrapper
+** which always has the same well-defined interface.
+*/
+static int posixOpen(const char *zFile, int flags, int mode){
+  return open(zFile, flags, mode);
+}
+
+/* Forward reference */
+static int openDirectory(const char*, int*);
+static int unixGetpagesize(void);
+
+/*
+** Many system calls are accessed through pointer-to-functions so that
+** they may be overridden at runtime to facilitate fault injection during
+** testing and sandboxing.  The following array holds the names and pointers
+** to all overrideable system calls.
+*/
+static struct unix_syscall {
+  const char *zName;            /* Name of the system call */
+  sqlite3_syscall_ptr pCurrent; /* Current value of the system call */
+  sqlite3_syscall_ptr pDefault; /* Default value */
+} aSyscall[] = {
+  { "open",         (sqlite3_syscall_ptr)posixOpen,  0  },
+#define osOpen      ((int(*)(const char*,int,int))aSyscall[0].pCurrent)
+
+  { "close",        (sqlite3_syscall_ptr)close,      0  },
+#define osClose     ((int(*)(int))aSyscall[1].pCurrent)
+
+  { "access",       (sqlite3_syscall_ptr)access,     0  },
+#define osAccess    ((int(*)(const char*,int))aSyscall[2].pCurrent)
+
+  { "getcwd",       (sqlite3_syscall_ptr)getcwd,     0  },
+#define osGetcwd    ((char*(*)(char*,size_t))aSyscall[3].pCurrent)
+
+  { "stat",         (sqlite3_syscall_ptr)stat,       0  },
+#define osStat      ((int(*)(const char*,struct stat*))aSyscall[4].pCurrent)
+
+/*
+** The DJGPP compiler environment looks mostly like Unix, but it
+** lacks the fcntl() system call.  So redefine fcntl() to be something
+** that always succeeds.  This means that locking does not occur under
+** DJGPP.  But it is DOS - what did you expect?
+*/
+#ifdef __DJGPP__
+  { "fstat",        0,                 0  },
+#define osFstat(a,b,c)    0
+#else     
+  { "fstat",        (sqlite3_syscall_ptr)fstat,      0  },
+#define osFstat     ((int(*)(int,struct stat*))aSyscall[5].pCurrent)
+#endif
+
+  { "ftruncate",    (sqlite3_syscall_ptr)ftruncate,  0  },
+#define osFtruncate ((int(*)(int,off_t))aSyscall[6].pCurrent)
+
+  { "fcntl",        (sqlite3_syscall_ptr)fcntl,      0  },
+#define osFcntl     ((int(*)(int,int,...))aSyscall[7].pCurrent)
+
+  { "read",         (sqlite3_syscall_ptr)read,       0  },
+#define osRead      ((ssize_t(*)(int,void*,size_t))aSyscall[8].pCurrent)
+
+#if defined(USE_PREAD) || SQLITE_ENABLE_LOCKING_STYLE
+  { "pread",        (sqlite3_syscall_ptr)pread,      0  },
+#else
+  { "pread",        (sqlite3_syscall_ptr)0,          0  },
+#endif
+#define osPread     ((ssize_t(*)(int,void*,size_t,off_t))aSyscall[9].pCurrent)
+
+#if defined(USE_PREAD64)
+  { "pread64",      (sqlite3_syscall_ptr)pread64,    0  },
+#else
+  { "pread64",      (sqlite3_syscall_ptr)0,          0  },
+#endif
+#define osPread64 ((ssize_t(*)(int,void*,size_t,off64_t))aSyscall[10].pCurrent)
+
+  { "write",        (sqlite3_syscall_ptr)write,      0  },
+#define osWrite     ((ssize_t(*)(int,const void*,size_t))aSyscall[11].pCurrent)
+
+#if defined(USE_PREAD) || SQLITE_ENABLE_LOCKING_STYLE
+  { "pwrite",       (sqlite3_syscall_ptr)pwrite,     0  },
+#else
+  { "pwrite",       (sqlite3_syscall_ptr)0,          0  },
+#endif
+#define osPwrite    ((ssize_t(*)(int,const void*,size_t,off_t))\
+                    aSyscall[12].pCurrent)
+
+#if defined(USE_PREAD64)
+  { "pwrite64",     (sqlite3_syscall_ptr)pwrite64,   0  },
+#else
+  { "pwrite64",     (sqlite3_syscall_ptr)0,          0  },
+#endif
+#define osPwrite64  ((ssize_t(*)(int,const void*,size_t,off64_t))\
+                    aSyscall[13].pCurrent)
+
+  { "fchmod",       (sqlite3_syscall_ptr)fchmod,          0  },
+#define osFchmod    ((int(*)(int,mode_t))aSyscall[14].pCurrent)
+
+#if defined(HAVE_POSIX_FALLOCATE) && HAVE_POSIX_FALLOCATE
+  { "fallocate",    (sqlite3_syscall_ptr)posix_fallocate,  0 },
+#else
+  { "fallocate",    (sqlite3_syscall_ptr)0,                0 },
+#endif
+#define osFallocate ((int(*)(int,off_t,off_t))aSyscall[15].pCurrent)
+
+  { "unlink",       (sqlite3_syscall_ptr)unlink,           0 },
+#define osUnlink    ((int(*)(const char*))aSyscall[16].pCurrent)
+
+  { "openDirectory",    (sqlite3_syscall_ptr)openDirectory,      0 },
+#define osOpenDirectory ((int(*)(const char*,int*))aSyscall[17].pCurrent)
+
+  { "mkdir",        (sqlite3_syscall_ptr)mkdir,           0 },
+#define osMkdir     ((int(*)(const char*,mode_t))aSyscall[18].pCurrent)
+
+  { "rmdir",        (sqlite3_syscall_ptr)rmdir,           0 },
+#define osRmdir     ((int(*)(const char*))aSyscall[19].pCurrent)
+
+#if defined(HAVE_FCHOWN)
+  { "fchown",       (sqlite3_syscall_ptr)fchown,          0 },
+#else
+  { "fchown",       (sqlite3_syscall_ptr)0,               0 },
+#endif
+#define osFchown    ((int(*)(int,uid_t,gid_t))aSyscall[20].pCurrent)
+
+  { "geteuid",      (sqlite3_syscall_ptr)geteuid,         0 },
+#define osGeteuid   ((uid_t(*)(void))aSyscall[21].pCurrent)
+
+#if !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0
+  { "mmap",         (sqlite3_syscall_ptr)mmap,            0 },
+#else
+  { "mmap",         (sqlite3_syscall_ptr)0,               0 },
+#endif
+#define osMmap ((void*(*)(void*,size_t,int,int,int,off_t))aSyscall[22].pCurrent)
+
+#if !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0
+  { "munmap",       (sqlite3_syscall_ptr)munmap,          0 },
+#else
+  { "munmap",       (sqlite3_syscall_ptr)0,               0 },
+#endif
+#define osMunmap ((void*(*)(void*,size_t))aSyscall[23].pCurrent)
+
+#if HAVE_MREMAP && (!defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0)
+  { "mremap",       (sqlite3_syscall_ptr)mremap,          0 },
+#else
+  { "mremap",       (sqlite3_syscall_ptr)0,               0 },
+#endif
+#define osMremap ((void*(*)(void*,size_t,size_t,int,...))aSyscall[24].pCurrent)
+
+#if !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0
+  { "getpagesize",  (sqlite3_syscall_ptr)unixGetpagesize, 0 },
+#else
+  { "getpagesize",  (sqlite3_syscall_ptr)0,               0 },
+#endif
+#define osGetpagesize ((int(*)(void))aSyscall[25].pCurrent)
+
+#if defined(HAVE_READLINK)
+  { "readlink",     (sqlite3_syscall_ptr)readlink,        0 },
+#else
+  { "readlink",     (sqlite3_syscall_ptr)0,               0 },
+#endif
+#define osReadlink ((ssize_t(*)(const char*,char*,size_t))aSyscall[26].pCurrent)
+
+#if defined(HAVE_LSTAT)
+  { "lstat",         (sqlite3_syscall_ptr)lstat,          0 },
+#else
+  { "lstat",         (sqlite3_syscall_ptr)0,              0 },
+#endif
+#define osLstat      ((int(*)(const char*,struct stat*))aSyscall[27].pCurrent)
+
+}; /* End of the overrideable system calls */
+
+
+/*
+** On some systems, calls to fchown() will trigger a message in a security
+** log if they come from non-root processes.  So avoid calling fchown() if
+** we are not running as root.
+*/
+static int robustFchown(int fd, uid_t uid, gid_t gid){
+#if defined(HAVE_FCHOWN)
+  return osGeteuid() ? 0 : osFchown(fd,uid,gid);
+#else
+  return 0;
+#endif
+}
+
+/*
+** This is the xSetSystemCall() method of sqlite3_vfs for all of the
+** "unix" VFSes.  Return SQLITE_OK opon successfully updating the
+** system call pointer, or SQLITE_NOTFOUND if there is no configurable
+** system call named zName.
+*/
+static int unixSetSystemCall(
+  sqlite3_vfs *pNotUsed,        /* The VFS pointer.  Not used */
+  const char *zName,            /* Name of system call to override */
+  sqlite3_syscall_ptr pNewFunc  /* Pointer to new system call value */
+){
+  unsigned int i;
+  int rc = SQLITE_NOTFOUND;
+
+  UNUSED_PARAMETER(pNotUsed);
+  if( zName==0 ){
+    /* If no zName is given, restore all system calls to their default
+    ** settings and return NULL
+    */
+    rc = SQLITE_OK;
+    for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
+      if( aSyscall[i].pDefault ){
+        aSyscall[i].pCurrent = aSyscall[i].pDefault;
+      }
+    }
+  }else{
+    /* If zName is specified, operate on only the one system call
+    ** specified.
+    */
+    for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
+      if( strcmp(zName, aSyscall[i].zName)==0 ){
+        if( aSyscall[i].pDefault==0 ){
+          aSyscall[i].pDefault = aSyscall[i].pCurrent;
+        }
+        rc = SQLITE_OK;
+        if( pNewFunc==0 ) pNewFunc = aSyscall[i].pDefault;
+        aSyscall[i].pCurrent = pNewFunc;
+        break;
+      }
+    }
+  }
+  return rc;
+}
+
+/*
+** Return the value of a system call.  Return NULL if zName is not a
+** recognized system call name.  NULL is also returned if the system call
+** is currently undefined.
+*/
+static sqlite3_syscall_ptr unixGetSystemCall(
+  sqlite3_vfs *pNotUsed,
+  const char *zName
+){
+  unsigned int i;
+
+  UNUSED_PARAMETER(pNotUsed);
+  for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
+    if( strcmp(zName, aSyscall[i].zName)==0 ) return aSyscall[i].pCurrent;
+  }
+  return 0;
+}
+
+/*
+** Return the name of the first system call after zName.  If zName==NULL
+** then return the name of the first system call.  Return NULL if zName
+** is the last system call or if zName is not the name of a valid
+** system call.
+*/
+static const char *unixNextSystemCall(sqlite3_vfs *p, const char *zName){
+  int i = -1;
+
+  UNUSED_PARAMETER(p);
+  if( zName ){
+    for(i=0; i<ArraySize(aSyscall)-1; i++){
+      if( strcmp(zName, aSyscall[i].zName)==0 ) break;
+    }
+  }
+  for(i++; i<ArraySize(aSyscall); i++){
+    if( aSyscall[i].pCurrent!=0 ) return aSyscall[i].zName;
+  }
+  return 0;
+}
+
+/*
+** Do not accept any file descriptor less than this value, in order to avoid
+** opening database file using file descriptors that are commonly used for 
+** standard input, output, and error.
+*/
+#ifndef SQLITE_MINIMUM_FILE_DESCRIPTOR
+# define SQLITE_MINIMUM_FILE_DESCRIPTOR 3
+#endif
+
+/*
+** Invoke open().  Do so multiple times, until it either succeeds or
+** fails for some reason other than EINTR.
+**
+** If the file creation mode "m" is 0 then set it to the default for
+** SQLite.  The default is SQLITE_DEFAULT_FILE_PERMISSIONS (normally
+** 0644) as modified by the system umask.  If m is not 0, then
+** make the file creation mode be exactly m ignoring the umask.
+**
+** The m parameter will be non-zero only when creating -wal, -journal,
+** and -shm files.  We want those files to have *exactly* the same
+** permissions as their original database, unadulterated by the umask.
+** In that way, if a database file is -rw-rw-rw or -rw-rw-r-, and a
+** transaction crashes and leaves behind hot journals, then any
+** process that is able to write to the database will also be able to
+** recover the hot journals.
+*/
+static int robust_open(const char *z, int f, mode_t m){
+  int fd;
+  mode_t m2 = m ? m : SQLITE_DEFAULT_FILE_PERMISSIONS;
+  while(1){
+#if defined(O_CLOEXEC)
+    fd = osOpen(z,f|O_CLOEXEC,m2);
+#else
+    fd = osOpen(z,f,m2);
+#endif
+    if( fd<0 ){
+      if( errno==EINTR ) continue;
+      break;
+    }
+    if( fd>=SQLITE_MINIMUM_FILE_DESCRIPTOR ) break;
+    osClose(fd);
+    sqlite3_log(SQLITE_WARNING, 
+                "attempt to open \"%s\" as file descriptor %d", z, fd);
+    fd = -1;
+    if( osOpen("/dev/null", f, m)<0 ) break;
+  }
+  if( fd>=0 ){
+    if( m!=0 ){
+      struct stat statbuf;
+      if( osFstat(fd, &statbuf)==0 
+       && statbuf.st_size==0
+       && (statbuf.st_mode&0777)!=m 
+      ){
+        osFchmod(fd, m);
+      }
+    }
+#if defined(FD_CLOEXEC) && (!defined(O_CLOEXEC) || O_CLOEXEC==0)
+    osFcntl(fd, F_SETFD, osFcntl(fd, F_GETFD, 0) | FD_CLOEXEC);
+#endif
+  }
+  return fd;
+}
+
+/*
+** Helper functions to obtain and relinquish the global mutex. The
+** global mutex is used to protect the unixInodeInfo and
+** vxworksFileId objects used by this file, all of which may be 
+** shared by multiple threads.
+**
+** Function unixMutexHeld() is used to assert() that the global mutex 
+** is held when required. This function is only used as part of assert() 
+** statements. e.g.
+**
+**   unixEnterMutex()
+**     assert( unixMutexHeld() );
+**   unixEnterLeave()
+*/
+static void unixEnterMutex(void){
+  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_VFS1));
+}
+static void unixLeaveMutex(void){
+  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_VFS1));
+}
+#ifdef SQLITE_DEBUG
+static int unixMutexHeld(void) {
+  return sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_VFS1));
+}
+#endif
+
+
+#ifdef SQLITE_HAVE_OS_TRACE
+/*
+** Helper function for printing out trace information from debugging
+** binaries. This returns the string representation of the supplied
+** integer lock-type.
+*/
+static const char *azFileLock(int eFileLock){
+  switch( eFileLock ){
+    case NO_LOCK: return "NONE";
+    case SHARED_LOCK: return "SHARED";
+    case RESERVED_LOCK: return "RESERVED";
+    case PENDING_LOCK: return "PENDING";
+    case EXCLUSIVE_LOCK: return "EXCLUSIVE";
+  }
+  return "ERROR";
+}
+#endif
+
+#ifdef SQLITE_LOCK_TRACE
+/*
+** Print out information about all locking operations.
+**
+** This routine is used for troubleshooting locks on multithreaded
+** platforms.  Enable by compiling with the -DSQLITE_LOCK_TRACE
+** command-line option on the compiler.  This code is normally
+** turned off.
+*/
+static int lockTrace(int fd, int op, struct flock *p){
+  char *zOpName, *zType;
+  int s;
+  int savedErrno;
+  if( op==F_GETLK ){
+    zOpName = "GETLK";
+  }else if( op==F_SETLK ){
+    zOpName = "SETLK";
+  }else{
+    s = osFcntl(fd, op, p);
+    sqlite3DebugPrintf("fcntl unknown %d %d %d\n", fd, op, s);
+    return s;
+  }
+  if( p->l_type==F_RDLCK ){
+    zType = "RDLCK";
+  }else if( p->l_type==F_WRLCK ){
+    zType = "WRLCK";
+  }else if( p->l_type==F_UNLCK ){
+    zType = "UNLCK";
+  }else{
+    assert( 0 );
+  }
+  assert( p->l_whence==SEEK_SET );
+  s = osFcntl(fd, op, p);
+  savedErrno = errno;
+  sqlite3DebugPrintf("fcntl %d %d %s %s %d %d %d %d\n",
+     threadid, fd, zOpName, zType, (int)p->l_start, (int)p->l_len,
+     (int)p->l_pid, s);
+  if( s==(-1) && op==F_SETLK && (p->l_type==F_RDLCK || p->l_type==F_WRLCK) ){
+    struct flock l2;
+    l2 = *p;
+    osFcntl(fd, F_GETLK, &l2);
+    if( l2.l_type==F_RDLCK ){
+      zType = "RDLCK";
+    }else if( l2.l_type==F_WRLCK ){
+      zType = "WRLCK";
+    }else if( l2.l_type==F_UNLCK ){
+      zType = "UNLCK";
+    }else{
+      assert( 0 );
+    }
+    sqlite3DebugPrintf("fcntl-failure-reason: %s %d %d %d\n",
+       zType, (int)l2.l_start, (int)l2.l_len, (int)l2.l_pid);
+  }
+  errno = savedErrno;
+  return s;
+}
+#undef osFcntl
+#define osFcntl lockTrace
+#endif /* SQLITE_LOCK_TRACE */
+
+/*
+** Retry ftruncate() calls that fail due to EINTR
+**
+** All calls to ftruncate() within this file should be made through
+** this wrapper.  On the Android platform, bypassing the logic below
+** could lead to a corrupt database.
+*/
+static int robust_ftruncate(int h, sqlite3_int64 sz){
+  int rc;
+#ifdef __ANDROID__
+  /* On Android, ftruncate() always uses 32-bit offsets, even if 
+  ** _FILE_OFFSET_BITS=64 is defined. This means it is unsafe to attempt to
+  ** truncate a file to any size larger than 2GiB. Silently ignore any
+  ** such attempts.  */
+  if( sz>(sqlite3_int64)0x7FFFFFFF ){
+    rc = SQLITE_OK;
+  }else
+#endif
+  do{ rc = osFtruncate(h,sz); }while( rc<0 && errno==EINTR );
+  return rc;
+}
+
+/*
+** This routine translates a standard POSIX errno code into something
+** useful to the clients of the sqlite3 functions.  Specifically, it is
+** intended to translate a variety of "try again" errors into SQLITE_BUSY
+** and a variety of "please close the file descriptor NOW" errors into 
+** SQLITE_IOERR
+** 
+** Errors during initialization of locks, or file system support for locks,
+** should handle ENOLCK, ENOTSUP, EOPNOTSUPP separately.
+*/
+static int sqliteErrorFromPosixError(int posixError, int sqliteIOErr) {
+  assert( (sqliteIOErr == SQLITE_IOERR_LOCK) || 
+          (sqliteIOErr == SQLITE_IOERR_UNLOCK) || 
+          (sqliteIOErr == SQLITE_IOERR_RDLOCK) ||
+          (sqliteIOErr == SQLITE_IOERR_CHECKRESERVEDLOCK) );
+  switch (posixError) {
+  case EACCES: 
+  case EAGAIN:
+  case ETIMEDOUT:
+  case EBUSY:
+  case EINTR:
+  case ENOLCK:  
+    /* random NFS retry error, unless during file system support 
+     * introspection, in which it actually means what it says */
+    return SQLITE_BUSY;
+    
+  case EPERM: 
+    return SQLITE_PERM;
+    
+  default: 
+    return sqliteIOErr;
+  }
+}
+
+
+/******************************************************************************
+****************** Begin Unique File ID Utility Used By VxWorks ***************
+**
+** On most versions of unix, we can get a unique ID for a file by concatenating
+** the device number and the inode number.  But this does not work on VxWorks.
+** On VxWorks, a unique file id must be based on the canonical filename.
+**
+** A pointer to an instance of the following structure can be used as a
+** unique file ID in VxWorks.  Each instance of this structure contains
+** a copy of the canonical filename.  There is also a reference count.  
+** The structure is reclaimed when the number of pointers to it drops to
+** zero.
+**
+** There are never very many files open at one time and lookups are not
+** a performance-critical path, so it is sufficient to put these
+** structures on a linked list.
+*/
+struct vxworksFileId {
+  struct vxworksFileId *pNext;  /* Next in a list of them all */
+  int nRef;                     /* Number of references to this one */
+  int nName;                    /* Length of the zCanonicalName[] string */
+  char *zCanonicalName;         /* Canonical filename */
+};
+
+#if OS_VXWORKS
+/* 
+** All unique filenames are held on a linked list headed by this
+** variable:
+*/
+static struct vxworksFileId *vxworksFileList = 0;
+
+/*
+** Simplify a filename into its canonical form
+** by making the following changes:
+**
+**  * removing any trailing and duplicate /
+**  * convert /./ into just /
+**  * convert /A/../ where A is any simple name into just /
+**
+** Changes are made in-place.  Return the new name length.
+**
+** The original filename is in z[0..n-1].  Return the number of
+** characters in the simplified name.
+*/
+static int vxworksSimplifyName(char *z, int n){
+  int i, j;
+  while( n>1 && z[n-1]=='/' ){ n--; }
+  for(i=j=0; i<n; i++){
+    if( z[i]=='/' ){
+      if( z[i+1]=='/' ) continue;
+      if( z[i+1]=='.' && i+2<n && z[i+2]=='/' ){
+        i += 1;
+        continue;
+      }
+      if( z[i+1]=='.' && i+3<n && z[i+2]=='.' && z[i+3]=='/' ){
+        while( j>0 && z[j-1]!='/' ){ j--; }
+        if( j>0 ){ j--; }
+        i += 2;
+        continue;
+      }
+    }
+    z[j++] = z[i];
+  }
+  z[j] = 0;
+  return j;
+}
+
+/*
+** Find a unique file ID for the given absolute pathname.  Return
+** a pointer to the vxworksFileId object.  This pointer is the unique
+** file ID.
+**
+** The nRef field of the vxworksFileId object is incremented before
+** the object is returned.  A new vxworksFileId object is created
+** and added to the global list if necessary.
+**
+** If a memory allocation error occurs, return NULL.
+*/
+static struct vxworksFileId *vxworksFindFileId(const char *zAbsoluteName){
+  struct vxworksFileId *pNew;         /* search key and new file ID */
+  struct vxworksFileId *pCandidate;   /* For looping over existing file IDs */
+  int n;                              /* Length of zAbsoluteName string */
+
+  assert( zAbsoluteName[0]=='/' );
+  n = (int)strlen(zAbsoluteName);
+  pNew = sqlite3_malloc64( sizeof(*pNew) + (n+1) );
+  if( pNew==0 ) return 0;
+  pNew->zCanonicalName = (char*)&pNew[1];
+  memcpy(pNew->zCanonicalName, zAbsoluteName, n+1);
+  n = vxworksSimplifyName(pNew->zCanonicalName, n);
+
+  /* Search for an existing entry that matching the canonical name.
+  ** If found, increment the reference count and return a pointer to
+  ** the existing file ID.
+  */
+  unixEnterMutex();
+  for(pCandidate=vxworksFileList; pCandidate; pCandidate=pCandidate->pNext){
+    if( pCandidate->nName==n 
+     && memcmp(pCandidate->zCanonicalName, pNew->zCanonicalName, n)==0
+    ){
+       sqlite3_free(pNew);
+       pCandidate->nRef++;
+       unixLeaveMutex();
+       return pCandidate;
+    }
+  }
+
+  /* No match was found.  We will make a new file ID */
+  pNew->nRef = 1;
+  pNew->nName = n;
+  pNew->pNext = vxworksFileList;
+  vxworksFileList = pNew;
+  unixLeaveMutex();
+  return pNew;
+}
+
+/*
+** Decrement the reference count on a vxworksFileId object.  Free
+** the object when the reference count reaches zero.
+*/
+static void vxworksReleaseFileId(struct vxworksFileId *pId){
+  unixEnterMutex();
+  assert( pId->nRef>0 );
+  pId->nRef--;
+  if( pId->nRef==0 ){
+    struct vxworksFileId **pp;
+    for(pp=&vxworksFileList; *pp && *pp!=pId; pp = &((*pp)->pNext)){}
+    assert( *pp==pId );
+    *pp = pId->pNext;
+    sqlite3_free(pId);
+  }
+  unixLeaveMutex();
+}
+#endif /* OS_VXWORKS */
+/*************** End of Unique File ID Utility Used By VxWorks ****************
+******************************************************************************/
+
+
+/******************************************************************************
+*************************** Posix Advisory Locking ****************************
+**
+** POSIX advisory locks are broken by design.  ANSI STD 1003.1 (1996)
+** section 6.5.2.2 lines 483 through 490 specify that when a process
+** sets or clears a lock, that operation overrides any prior locks set
+** by the same process.  It does not explicitly say so, but this implies
+** that it overrides locks set by the same process using a different
+** file descriptor.  Consider this test case:
+**
+**       int fd1 = open("./file1", O_RDWR|O_CREAT, 0644);
+**       int fd2 = open("./file2", O_RDWR|O_CREAT, 0644);
+**
+** Suppose ./file1 and ./file2 are really the same file (because
+** one is a hard or symbolic link to the other) then if you set
+** an exclusive lock on fd1, then try to get an exclusive lock
+** on fd2, it works.  I would have expected the second lock to
+** fail since there was already a lock on the file due to fd1.
+** But not so.  Since both locks came from the same process, the
+** second overrides the first, even though they were on different
+** file descriptors opened on different file names.
+**
+** This means that we cannot use POSIX locks to synchronize file access
+** among competing threads of the same process.  POSIX locks will work fine
+** to synchronize access for threads in separate processes, but not
+** threads within the same process.
+**
+** To work around the problem, SQLite has to manage file locks internally
+** on its own.  Whenever a new database is opened, we have to find the
+** specific inode of the database file (the inode is determined by the
+** st_dev and st_ino fields of the stat structure that fstat() fills in)
+** and check for locks already existing on that inode.  When locks are
+** created or removed, we have to look at our own internal record of the
+** locks to see if another thread has previously set a lock on that same
+** inode.
+**
+** (Aside: The use of inode numbers as unique IDs does not work on VxWorks.
+** For VxWorks, we have to use the alternative unique ID system based on
+** canonical filename and implemented in the previous division.)
+**
+** The sqlite3_file structure for POSIX is no longer just an integer file
+** descriptor.  It is now a structure that holds the integer file
+** descriptor and a pointer to a structure that describes the internal
+** locks on the corresponding inode.  There is one locking structure
+** per inode, so if the same inode is opened twice, both unixFile structures
+** point to the same locking structure.  The locking structure keeps
+** a reference count (so we will know when to delete it) and a "cnt"
+** field that tells us its internal lock status.  cnt==0 means the
+** file is unlocked.  cnt==-1 means the file has an exclusive lock.
+** cnt>0 means there are cnt shared locks on the file.
+**
+** Any attempt to lock or unlock a file first checks the locking
+** structure.  The fcntl() system call is only invoked to set a 
+** POSIX lock if the internal lock structure transitions between
+** a locked and an unlocked state.
+**
+** But wait:  there are yet more problems with POSIX advisory locks.
+**
+** If you close a file descriptor that points to a file that has locks,
+** all locks on that file that are owned by the current process are
+** released.  To work around this problem, each unixInodeInfo object
+** maintains a count of the number of pending locks on tha inode.
+** When an attempt is made to close an unixFile, if there are
+** other unixFile open on the same inode that are holding locks, the call
+** to close() the file descriptor is deferred until all of the locks clear.
+** The unixInodeInfo structure keeps a list of file descriptors that need to
+** be closed and that list is walked (and cleared) when the last lock
+** clears.
+**
+** Yet another problem:  LinuxThreads do not play well with posix locks.
+**
+** Many older versions of linux use the LinuxThreads library which is
+** not posix compliant.  Under LinuxThreads, a lock created by thread
+** A cannot be modified or overridden by a different thread B.
+** Only thread A can modify the lock.  Locking behavior is correct
+** if the appliation uses the newer Native Posix Thread Library (NPTL)
+** on linux - with NPTL a lock created by thread A can override locks
+** in thread B.  But there is no way to know at compile-time which
+** threading library is being used.  So there is no way to know at
+** compile-time whether or not thread A can override locks on thread B.
+** One has to do a run-time check to discover the behavior of the
+** current process.
+**
+** SQLite used to support LinuxThreads.  But support for LinuxThreads
+** was dropped beginning with version 3.7.0.  SQLite will still work with
+** LinuxThreads provided that (1) there is no more than one connection 
+** per database file in the same process and (2) database connections
+** do not move across threads.
+*/
+
+/*
+** An instance of the following structure serves as the key used
+** to locate a particular unixInodeInfo object.
+*/
+struct unixFileId {
+  dev_t dev;                  /* Device number */
+#if OS_VXWORKS
+  struct vxworksFileId *pId;  /* Unique file ID for vxworks. */
+#else
+  ino_t ino;                  /* Inode number */
+#endif
+};
+
+/*
+** An instance of the following structure is allocated for each open
+** inode.  Or, on LinuxThreads, there is one of these structures for
+** each inode opened by each thread.
+**
+** A single inode can have multiple file descriptors, so each unixFile
+** structure contains a pointer to an instance of this object and this
+** object keeps a count of the number of unixFile pointing to it.
+*/
+struct unixInodeInfo {
+  struct unixFileId fileId;       /* The lookup key */
+  int nShared;                    /* Number of SHARED locks held */
+  unsigned char eFileLock;        /* One of SHARED_LOCK, RESERVED_LOCK etc. */
+  unsigned char bProcessLock;     /* An exclusive process lock is held */
+  int nRef;                       /* Number of pointers to this structure */
+  unixShmNode *pShmNode;          /* Shared memory associated with this inode */
+  int nLock;                      /* Number of outstanding file locks */
+  UnixUnusedFd *pUnused;          /* Unused file descriptors to close */
+  unixInodeInfo *pNext;           /* List of all unixInodeInfo objects */
+  unixInodeInfo *pPrev;           /*    .... doubly linked */
+#if SQLITE_ENABLE_LOCKING_STYLE
+  unsigned long long sharedByte;  /* for AFP simulated shared lock */
+#endif
+#if OS_VXWORKS
+  sem_t *pSem;                    /* Named POSIX semaphore */
+  char aSemName[MAX_PATHNAME+2];  /* Name of that semaphore */
+#endif
+};
+
+/*
+** A lists of all unixInodeInfo objects.
+*/
+static unixInodeInfo *inodeList = 0;
+
+/*
+**
+** This function - unixLogErrorAtLine(), is only ever called via the macro
+** unixLogError().
+**
+** It is invoked after an error occurs in an OS function and errno has been
+** set. It logs a message using sqlite3_log() containing the current value of
+** errno and, if possible, the human-readable equivalent from strerror() or
+** strerror_r().
+**
+** The first argument passed to the macro should be the error code that
+** will be returned to SQLite (e.g. SQLITE_IOERR_DELETE, SQLITE_CANTOPEN). 
+** The two subsequent arguments should be the name of the OS function that
+** failed (e.g. "unlink", "open") and the associated file-system path,
+** if any.
+*/
+#define unixLogError(a,b,c)     unixLogErrorAtLine(a,b,c,__LINE__)
+static int unixLogErrorAtLine(
+  int errcode,                    /* SQLite error code */
+  const char *zFunc,              /* Name of OS function that failed */
+  const char *zPath,              /* File path associated with error */
+  int iLine                       /* Source line number where error occurred */
+){
+  char *zErr;                     /* Message from strerror() or equivalent */
+  int iErrno = errno;             /* Saved syscall error number */
+
+  /* If this is not a threadsafe build (SQLITE_THREADSAFE==0), then use
+  ** the strerror() function to obtain the human-readable error message
+  ** equivalent to errno. Otherwise, use strerror_r().
+  */ 
+#if SQLITE_THREADSAFE && defined(HAVE_STRERROR_R)
+  char aErr[80];
+  memset(aErr, 0, sizeof(aErr));
+  zErr = aErr;
+
+  /* If STRERROR_R_CHAR_P (set by autoconf scripts) or __USE_GNU is defined,
+  ** assume that the system provides the GNU version of strerror_r() that
+  ** returns a pointer to a buffer containing the error message. That pointer 
+  ** may point to aErr[], or it may point to some static storage somewhere. 
+  ** Otherwise, assume that the system provides the POSIX version of 
+  ** strerror_r(), which always writes an error message into aErr[].
+  **
+  ** If the code incorrectly assumes that it is the POSIX version that is
+  ** available, the error message will often be an empty string. Not a
+  ** huge problem. Incorrectly concluding that the GNU version is available 
+  ** could lead to a segfault though.
+  */
+#if defined(STRERROR_R_CHAR_P) || defined(__USE_GNU)
+  zErr = 
+# endif
+  strerror_r(iErrno, aErr, sizeof(aErr)-1);
+
+#elif SQLITE_THREADSAFE
+  /* This is a threadsafe build, but strerror_r() is not available. */
+  zErr = "";
+#else
+  /* Non-threadsafe build, use strerror(). */
+  zErr = strerror(iErrno);
+#endif
+
+  if( zPath==0 ) zPath = "";
+  sqlite3_log(errcode,
+      "os_unix.c:%d: (%d) %s(%s) - %s",
+      iLine, iErrno, zFunc, zPath, zErr
+  );
+
+  return errcode;
+}
+
+/*
+** Close a file descriptor.
+**
+** We assume that close() almost always works, since it is only in a
+** very sick application or on a very sick platform that it might fail.
+** If it does fail, simply leak the file descriptor, but do log the
+** error.
+**
+** Note that it is not safe to retry close() after EINTR since the
+** file descriptor might have already been reused by another thread.
+** So we don't even try to recover from an EINTR.  Just log the error
+** and move on.
+*/
+static void robust_close(unixFile *pFile, int h, int lineno){
+  if( osClose(h) ){
+    unixLogErrorAtLine(SQLITE_IOERR_CLOSE, "close",
+                       pFile ? pFile->zPath : 0, lineno);
+  }
+}
+
+/*
+** Set the pFile->lastErrno.  Do this in a subroutine as that provides
+** a convenient place to set a breakpoint.
+*/
+static void storeLastErrno(unixFile *pFile, int error){
+  pFile->lastErrno = error;
+}
+
+/*
+** Close all file descriptors accumuated in the unixInodeInfo->pUnused list.
+*/ 
+static void closePendingFds(unixFile *pFile){
+  unixInodeInfo *pInode = pFile->pInode;
+  UnixUnusedFd *p;
+  UnixUnusedFd *pNext;
+  for(p=pInode->pUnused; p; p=pNext){
+    pNext = p->pNext;
+    robust_close(pFile, p->fd, __LINE__);
+    sqlite3_free(p);
+  }
+  pInode->pUnused = 0;
+}
+
+/*
+** Release a unixInodeInfo structure previously allocated by findInodeInfo().
+**
+** The mutex entered using the unixEnterMutex() function must be held
+** when this function is called.
+*/
+static void releaseInodeInfo(unixFile *pFile){
+  unixInodeInfo *pInode = pFile->pInode;
+  assert( unixMutexHeld() );
+  if( ALWAYS(pInode) ){
+    pInode->nRef--;
+    if( pInode->nRef==0 ){
+      assert( pInode->pShmNode==0 );
+      closePendingFds(pFile);
+      if( pInode->pPrev ){
+        assert( pInode->pPrev->pNext==pInode );
+        pInode->pPrev->pNext = pInode->pNext;
+      }else{
+        assert( inodeList==pInode );
+        inodeList = pInode->pNext;
+      }
+      if( pInode->pNext ){
+        assert( pInode->pNext->pPrev==pInode );
+        pInode->pNext->pPrev = pInode->pPrev;
+      }
+      sqlite3_free(pInode);
+    }
+  }
+}
+
+/*
+** Given a file descriptor, locate the unixInodeInfo object that
+** describes that file descriptor.  Create a new one if necessary.  The
+** return value might be uninitialized if an error occurs.
+**
+** The mutex entered using the unixEnterMutex() function must be held
+** when this function is called.
+**
+** Return an appropriate error code.
+*/
+static int findInodeInfo(
+  unixFile *pFile,               /* Unix file with file desc used in the key */
+  unixInodeInfo **ppInode        /* Return the unixInodeInfo object here */
+){
+  int rc;                        /* System call return code */
+  int fd;                        /* The file descriptor for pFile */
+  struct unixFileId fileId;      /* Lookup key for the unixInodeInfo */
+  struct stat statbuf;           /* Low-level file information */
+  unixInodeInfo *pInode = 0;     /* Candidate unixInodeInfo object */
+
+  assert( unixMutexHeld() );
+
+  /* Get low-level information about the file that we can used to
+  ** create a unique name for the file.
+  */
+  fd = pFile->h;
+  rc = osFstat(fd, &statbuf);
+  if( rc!=0 ){
+    storeLastErrno(pFile, errno);
+#if defined(EOVERFLOW) && defined(SQLITE_DISABLE_LFS)
+    if( pFile->lastErrno==EOVERFLOW ) return SQLITE_NOLFS;
+#endif
+    return SQLITE_IOERR;
+  }
+
+#ifdef __APPLE__
+  /* On OS X on an msdos filesystem, the inode number is reported
+  ** incorrectly for zero-size files.  See ticket #3260.  To work
+  ** around this problem (we consider it a bug in OS X, not SQLite)
+  ** we always increase the file size to 1 by writing a single byte
+  ** prior to accessing the inode number.  The one byte written is
+  ** an ASCII 'S' character which also happens to be the first byte
+  ** in the header of every SQLite database.  In this way, if there
+  ** is a race condition such that another thread has already populated
+  ** the first page of the database, no damage is done.
+  */
+  if( statbuf.st_size==0 && (pFile->fsFlags & SQLITE_FSFLAGS_IS_MSDOS)!=0 ){
+    do{ rc = osWrite(fd, "S", 1); }while( rc<0 && errno==EINTR );
+    if( rc!=1 ){
+      storeLastErrno(pFile, errno);
+      return SQLITE_IOERR;
+    }
+    rc = osFstat(fd, &statbuf);
+    if( rc!=0 ){
+      storeLastErrno(pFile, errno);
+      return SQLITE_IOERR;
+    }
+  }
+#endif
+
+  memset(&fileId, 0, sizeof(fileId));
+  fileId.dev = statbuf.st_dev;
+#if OS_VXWORKS
+  fileId.pId = pFile->pId;
+#else
+  fileId.ino = statbuf.st_ino;
+#endif
+  pInode = inodeList;
+  while( pInode && memcmp(&fileId, &pInode->fileId, sizeof(fileId)) ){
+    pInode = pInode->pNext;
+  }
+  if( pInode==0 ){
+    pInode = sqlite3_malloc64( sizeof(*pInode) );
+    if( pInode==0 ){
+      return SQLITE_NOMEM_BKPT;
+    }
+    memset(pInode, 0, sizeof(*pInode));
+    memcpy(&pInode->fileId, &fileId, sizeof(fileId));
+    pInode->nRef = 1;
+    pInode->pNext = inodeList;
+    pInode->pPrev = 0;
+    if( inodeList ) inodeList->pPrev = pInode;
+    inodeList = pInode;
+  }else{
+    pInode->nRef++;
+  }
+  *ppInode = pInode;
+  return SQLITE_OK;
+}
+
+/*
+** Return TRUE if pFile has been renamed or unlinked since it was first opened.
+*/
+static int fileHasMoved(unixFile *pFile){
+#if OS_VXWORKS
+  return pFile->pInode!=0 && pFile->pId!=pFile->pInode->fileId.pId;
+#else
+  struct stat buf;
+  return pFile->pInode!=0 &&
+      (osStat(pFile->zPath, &buf)!=0 || buf.st_ino!=pFile->pInode->fileId.ino);
+#endif
+}
+
+
+/*
+** Check a unixFile that is a database.  Verify the following:
+**
+** (1) There is exactly one hard link on the file
+** (2) The file is not a symbolic link
+** (3) The file has not been renamed or unlinked
+**
+** Issue sqlite3_log(SQLITE_WARNING,...) messages if anything is not right.
+*/
+static void verifyDbFile(unixFile *pFile){
+  struct stat buf;
+  int rc;
+
+  /* These verifications occurs for the main database only */
+  if( pFile->ctrlFlags & UNIXFILE_NOLOCK ) return;
+
+  rc = osFstat(pFile->h, &buf);
+  if( rc!=0 ){
+    sqlite3_log(SQLITE_WARNING, "cannot fstat db file %s", pFile->zPath);
+    return;
+  }
+  if( buf.st_nlink==0 ){
+    sqlite3_log(SQLITE_WARNING, "file unlinked while open: %s", pFile->zPath);
+    return;
+  }
+  if( buf.st_nlink>1 ){
+    sqlite3_log(SQLITE_WARNING, "multiple links to file: %s", pFile->zPath);
+    return;
+  }
+  if( fileHasMoved(pFile) ){
+    sqlite3_log(SQLITE_WARNING, "file renamed while open: %s", pFile->zPath);
+    return;
+  }
+}
+
+
+/*
+** This routine checks if there is a RESERVED lock held on the specified
+** file by this or any other process. If such a lock is held, set *pResOut
+** to a non-zero value otherwise *pResOut is set to zero.  The return value
+** is set to SQLITE_OK unless an I/O error occurs during lock checking.
+*/
+static int unixCheckReservedLock(sqlite3_file *id, int *pResOut){
+  int rc = SQLITE_OK;
+  int reserved = 0;
+  unixFile *pFile = (unixFile*)id;
+
+  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
+
+  assert( pFile );
+  assert( pFile->eFileLock<=SHARED_LOCK );
+  unixEnterMutex(); /* Because pFile->pInode is shared across threads */
+
+  /* Check if a thread in this process holds such a lock */
+  if( pFile->pInode->eFileLock>SHARED_LOCK ){
+    reserved = 1;
+  }
+
+  /* Otherwise see if some other process holds it.
+  */
+#ifndef __DJGPP__
+  if( !reserved && !pFile->pInode->bProcessLock ){
+    struct flock lock;
+    lock.l_whence = SEEK_SET;
+    lock.l_start = RESERVED_BYTE;
+    lock.l_len = 1;
+    lock.l_type = F_WRLCK;
+    if( osFcntl(pFile->h, F_GETLK, &lock) ){
+      rc = SQLITE_IOERR_CHECKRESERVEDLOCK;
+      storeLastErrno(pFile, errno);
+    } else if( lock.l_type!=F_UNLCK ){
+      reserved = 1;
+    }
+  }
+#endif
+  
+  unixLeaveMutex();
+  OSTRACE(("TEST WR-LOCK %d %d %d (unix)\n", pFile->h, rc, reserved));
+
+  *pResOut = reserved;
+  return rc;
+}
+
+/*
+** Attempt to set a system-lock on the file pFile.  The lock is 
+** described by pLock.
+**
+** If the pFile was opened read/write from unix-excl, then the only lock
+** ever obtained is an exclusive lock, and it is obtained exactly once
+** the first time any lock is attempted.  All subsequent system locking
+** operations become no-ops.  Locking operations still happen internally,
+** in order to coordinate access between separate database connections
+** within this process, but all of that is handled in memory and the
+** operating system does not participate.
+**
+** This function is a pass-through to fcntl(F_SETLK) if pFile is using
+** any VFS other than "unix-excl" or if pFile is opened on "unix-excl"
+** and is read-only.
+**
+** Zero is returned if the call completes successfully, or -1 if a call
+** to fcntl() fails. In this case, errno is set appropriately (by fcntl()).
+*/
+static int unixFileLock(unixFile *pFile, struct flock *pLock){
+  int rc;
+  unixInodeInfo *pInode = pFile->pInode;
+  assert( unixMutexHeld() );
+  assert( pInode!=0 );
+  if( (pFile->ctrlFlags & (UNIXFILE_EXCL|UNIXFILE_RDONLY))==UNIXFILE_EXCL ){
+    if( pInode->bProcessLock==0 ){
+      struct flock lock;
+      assert( pInode->nLock==0 );
+      lock.l_whence = SEEK_SET;
+      lock.l_start = SHARED_FIRST;
+      lock.l_len = SHARED_SIZE;
+      lock.l_type = F_WRLCK;
+      rc = osFcntl(pFile->h, F_SETLK, &lock);
+      if( rc<0 ) return rc;
+      pInode->bProcessLock = 1;
+      pInode->nLock++;
+    }else{
+      rc = 0;
+    }
+  }else{
+    rc = osFcntl(pFile->h, F_SETLK, pLock);
+  }
+  return rc;
+}
+
+/*
+** Lock the file with the lock specified by parameter eFileLock - one
+** of the following:
+**
+**     (1) SHARED_LOCK
+**     (2) RESERVED_LOCK
+**     (3) PENDING_LOCK
+**     (4) EXCLUSIVE_LOCK
+**
+** Sometimes when requesting one lock state, additional lock states
+** are inserted in between.  The locking might fail on one of the later
+** transitions leaving the lock state different from what it started but
+** still short of its goal.  The following chart shows the allowed
+** transitions and the inserted intermediate states:
+**
+**    UNLOCKED -> SHARED
+**    SHARED -> RESERVED
+**    SHARED -> (PENDING) -> EXCLUSIVE
+**    RESERVED -> (PENDING) -> EXCLUSIVE
+**    PENDING -> EXCLUSIVE
+**
+** This routine will only increase a lock.  Use the sqlite3OsUnlock()
+** routine to lower a locking level.
+*/
+static int unixLock(sqlite3_file *id, int eFileLock){
+  /* The following describes the implementation of the various locks and
+  ** lock transitions in terms of the POSIX advisory shared and exclusive
+  ** lock primitives (called read-locks and write-locks below, to avoid
+  ** confusion with SQLite lock names). The algorithms are complicated
+  ** slightly in order to be compatible with Windows95 systems simultaneously
+  ** accessing the same database file, in case that is ever required.
+  **
+  ** Symbols defined in os.h indentify the 'pending byte' and the 'reserved
+  ** byte', each single bytes at well known offsets, and the 'shared byte
+  ** range', a range of 510 bytes at a well known offset.
+  **
+  ** To obtain a SHARED lock, a read-lock is obtained on the 'pending
+  ** byte'.  If this is successful, 'shared byte range' is read-locked
+  ** and the lock on the 'pending byte' released.  (Legacy note:  When
+  ** SQLite was first developed, Windows95 systems were still very common,
+  ** and Widnows95 lacks a shared-lock capability.  So on Windows95, a
+  ** single randomly selected by from the 'shared byte range' is locked.
+  ** Windows95 is now pretty much extinct, but this work-around for the
+  ** lack of shared-locks on Windows95 lives on, for backwards
+  ** compatibility.)
+  **
+  ** A process may only obtain a RESERVED lock after it has a SHARED lock.
+  ** A RESERVED lock is implemented by grabbing a write-lock on the
+  ** 'reserved byte'. 
+  **
+  ** A process may only obtain a PENDING lock after it has obtained a
+  ** SHARED lock. A PENDING lock is implemented by obtaining a write-lock
+  ** on the 'pending byte'. This ensures that no new SHARED locks can be
+  ** obtained, but existing SHARED locks are allowed to persist. A process
+  ** does not have to obtain a RESERVED lock on the way to a PENDING lock.
+  ** This property is used by the algorithm for rolling back a journal file
+  ** after a crash.
+  **
+  ** An EXCLUSIVE lock, obtained after a PENDING lock is held, is
+  ** implemented by obtaining a write-lock on the entire 'shared byte
+  ** range'. Since all other locks require a read-lock on one of the bytes
+  ** within this range, this ensures that no other locks are held on the
+  ** database. 
+  */
+  int rc = SQLITE_OK;
+  unixFile *pFile = (unixFile*)id;
+  unixInodeInfo *pInode;
+  struct flock lock;
+  int tErrno = 0;
+
+  assert( pFile );
+  OSTRACE(("LOCK    %d %s was %s(%s,%d) pid=%d (unix)\n", pFile->h,
+      azFileLock(eFileLock), azFileLock(pFile->eFileLock),
+      azFileLock(pFile->pInode->eFileLock), pFile->pInode->nShared,
+      osGetpid(0)));
+
+  /* If there is already a lock of this type or more restrictive on the
+  ** unixFile, do nothing. Don't use the end_lock: exit path, as
+  ** unixEnterMutex() hasn't been called yet.
+  */
+  if( pFile->eFileLock>=eFileLock ){
+    OSTRACE(("LOCK    %d %s ok (already held) (unix)\n", pFile->h,
+            azFileLock(eFileLock)));
+    return SQLITE_OK;
+  }
+
+  /* Make sure the locking sequence is correct.
+  **  (1) We never move from unlocked to anything higher than shared lock.
+  **  (2) SQLite never explicitly requests a pendig lock.
+  **  (3) A shared lock is always held when a reserve lock is requested.
+  */
+  assert( pFile->eFileLock!=NO_LOCK || eFileLock==SHARED_LOCK );
+  assert( eFileLock!=PENDING_LOCK );
+  assert( eFileLock!=RESERVED_LOCK || pFile->eFileLock==SHARED_LOCK );
+
+  /* This mutex is needed because pFile->pInode is shared across threads
+  */
+  unixEnterMutex();
+  pInode = pFile->pInode;
+
+  /* If some thread using this PID has a lock via a different unixFile*
+  ** handle that precludes the requested lock, return BUSY.
+  */
+  if( (pFile->eFileLock!=pInode->eFileLock && 
+          (pInode->eFileLock>=PENDING_LOCK || eFileLock>SHARED_LOCK))
+  ){
+    rc = SQLITE_BUSY;
+    goto end_lock;
+  }
+
+  /* If a SHARED lock is requested, and some thread using this PID already
+  ** has a SHARED or RESERVED lock, then increment reference counts and
+  ** return SQLITE_OK.
+  */
+  if( eFileLock==SHARED_LOCK && 
+      (pInode->eFileLock==SHARED_LOCK || pInode->eFileLock==RESERVED_LOCK) ){
+    assert( eFileLock==SHARED_LOCK );
+    assert( pFile->eFileLock==0 );
+    assert( pInode->nShared>0 );
+    pFile->eFileLock = SHARED_LOCK;
+    pInode->nShared++;
+    pInode->nLock++;
+    goto end_lock;
+  }
+
+
+  /* A PENDING lock is needed before acquiring a SHARED lock and before
+  ** acquiring an EXCLUSIVE lock.  For the SHARED lock, the PENDING will
+  ** be released.
+  */
+  lock.l_len = 1L;
+  lock.l_whence = SEEK_SET;
+  if( eFileLock==SHARED_LOCK 
+      || (eFileLock==EXCLUSIVE_LOCK && pFile->eFileLock<PENDING_LOCK)
+  ){
+    lock.l_type = (eFileLock==SHARED_LOCK?F_RDLCK:F_WRLCK);
+    lock.l_start = PENDING_BYTE;
+    if( unixFileLock(pFile, &lock) ){
+      tErrno = errno;
+      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
+      if( rc!=SQLITE_BUSY ){
+        storeLastErrno(pFile, tErrno);
+      }
+      goto end_lock;
+    }
+  }
+
+
+  /* If control gets to this point, then actually go ahead and make
+  ** operating system calls for the specified lock.
+  */
+  if( eFileLock==SHARED_LOCK ){
+    assert( pInode->nShared==0 );
+    assert( pInode->eFileLock==0 );
+    assert( rc==SQLITE_OK );
+
+    /* Now get the read-lock */
+    lock.l_start = SHARED_FIRST;
+    lock.l_len = SHARED_SIZE;
+    if( unixFileLock(pFile, &lock) ){
+      tErrno = errno;
+      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
+    }
+
+    /* Drop the temporary PENDING lock */
+    lock.l_start = PENDING_BYTE;
+    lock.l_len = 1L;
+    lock.l_type = F_UNLCK;
+    if( unixFileLock(pFile, &lock) && rc==SQLITE_OK ){
+      /* This could happen with a network mount */
+      tErrno = errno;
+      rc = SQLITE_IOERR_UNLOCK; 
+    }
+
+    if( rc ){
+      if( rc!=SQLITE_BUSY ){
+        storeLastErrno(pFile, tErrno);
+      }
+      goto end_lock;
+    }else{
+      pFile->eFileLock = SHARED_LOCK;
+      pInode->nLock++;
+      pInode->nShared = 1;
+    }
+  }else if( eFileLock==EXCLUSIVE_LOCK && pInode->nShared>1 ){
+    /* We are trying for an exclusive lock but another thread in this
+    ** same process is still holding a shared lock. */
+    rc = SQLITE_BUSY;
+  }else{
+    /* The request was for a RESERVED or EXCLUSIVE lock.  It is
+    ** assumed that there is a SHARED or greater lock on the file
+    ** already.
+    */
+    assert( 0!=pFile->eFileLock );
+    lock.l_type = F_WRLCK;
+
+    assert( eFileLock==RESERVED_LOCK || eFileLock==EXCLUSIVE_LOCK );
+    if( eFileLock==RESERVED_LOCK ){
+      lock.l_start = RESERVED_BYTE;
+      lock.l_len = 1L;
+    }else{
+      lock.l_start = SHARED_FIRST;
+      lock.l_len = SHARED_SIZE;
+    }
+
+    if( unixFileLock(pFile, &lock) ){
+      tErrno = errno;
+      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
+      if( rc!=SQLITE_BUSY ){
+        storeLastErrno(pFile, tErrno);
+      }
+    }
+  }
+  
+
+#ifdef SQLITE_DEBUG
+  /* Set up the transaction-counter change checking flags when
+  ** transitioning from a SHARED to a RESERVED lock.  The change
+  ** from SHARED to RESERVED marks the beginning of a normal
+  ** write operation (not a hot journal rollback).
+  */
+  if( rc==SQLITE_OK
+   && pFile->eFileLock<=SHARED_LOCK
+   && eFileLock==RESERVED_LOCK
+  ){
+    pFile->transCntrChng = 0;
+    pFile->dbUpdate = 0;
+    pFile->inNormalWrite = 1;
+  }
+#endif
+
+
+  if( rc==SQLITE_OK ){
+    pFile->eFileLock = eFileLock;
+    pInode->eFileLock = eFileLock;
+  }else if( eFileLock==EXCLUSIVE_LOCK ){
+    pFile->eFileLock = PENDING_LOCK;
+    pInode->eFileLock = PENDING_LOCK;
+  }
+
+end_lock:
+  unixLeaveMutex();
+  OSTRACE(("LOCK    %d %s %s (unix)\n", pFile->h, azFileLock(eFileLock), 
+      rc==SQLITE_OK ? "ok" : "failed"));
+  return rc;
+}
+
+/*
+** Add the file descriptor used by file handle pFile to the corresponding
+** pUnused list.
+*/
+static void setPendingFd(unixFile *pFile){
+  unixInodeInfo *pInode = pFile->pInode;
+  UnixUnusedFd *p = pFile->pUnused;
+  p->pNext = pInode->pUnused;
+  pInode->pUnused = p;
+  pFile->h = -1;
+  pFile->pUnused = 0;
+}
+
+/*
+** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+** 
+** If handleNFSUnlock is true, then on downgrading an EXCLUSIVE_LOCK to SHARED
+** the byte range is divided into 2 parts and the first part is unlocked then
+** set to a read lock, then the other part is simply unlocked.  This works 
+** around a bug in BSD NFS lockd (also seen on MacOSX 10.3+) that fails to 
+** remove the write lock on a region when a read lock is set.
+*/
+static int posixUnlock(sqlite3_file *id, int eFileLock, int handleNFSUnlock){
+  unixFile *pFile = (unixFile*)id;
+  unixInodeInfo *pInode;
+  struct flock lock;
+  int rc = SQLITE_OK;
+
+  assert( pFile );
+  OSTRACE(("UNLOCK  %d %d was %d(%d,%d) pid=%d (unix)\n", pFile->h, eFileLock,
+      pFile->eFileLock, pFile->pInode->eFileLock, pFile->pInode->nShared,
+      osGetpid(0)));
+
+  assert( eFileLock<=SHARED_LOCK );
+  if( pFile->eFileLock<=eFileLock ){
+    return SQLITE_OK;
+  }
+  unixEnterMutex();
+  pInode = pFile->pInode;
+  assert( pInode->nShared!=0 );
+  if( pFile->eFileLock>SHARED_LOCK ){
+    assert( pInode->eFileLock==pFile->eFileLock );
+
+#ifdef SQLITE_DEBUG
+    /* When reducing a lock such that other processes can start
+    ** reading the database file again, make sure that the
+    ** transaction counter was updated if any part of the database
+    ** file changed.  If the transaction counter is not updated,
+    ** other connections to the same file might not realize that
+    ** the file has changed and hence might not know to flush their
+    ** cache.  The use of a stale cache can lead to database corruption.
+    */
+    pFile->inNormalWrite = 0;
+#endif
+
+    /* downgrading to a shared lock on NFS involves clearing the write lock
+    ** before establishing the readlock - to avoid a race condition we downgrade
+    ** the lock in 2 blocks, so that part of the range will be covered by a 
+    ** write lock until the rest is covered by a read lock:
+    **  1:   [WWWWW]
+    **  2:   [....W]
+    **  3:   [RRRRW]
+    **  4:   [RRRR.]
+    */
+    if( eFileLock==SHARED_LOCK ){
+#if !defined(__APPLE__) || !SQLITE_ENABLE_LOCKING_STYLE
+      (void)handleNFSUnlock;
+      assert( handleNFSUnlock==0 );
+#endif
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+      if( handleNFSUnlock ){
+        int tErrno;               /* Error code from system call errors */
+        off_t divSize = SHARED_SIZE - 1;
+        
+        lock.l_type = F_UNLCK;
+        lock.l_whence = SEEK_SET;
+        lock.l_start = SHARED_FIRST;
+        lock.l_len = divSize;
+        if( unixFileLock(pFile, &lock)==(-1) ){
+          tErrno = errno;
+          rc = SQLITE_IOERR_UNLOCK;
+          storeLastErrno(pFile, tErrno);
+          goto end_unlock;
+        }
+        lock.l_type = F_RDLCK;
+        lock.l_whence = SEEK_SET;
+        lock.l_start = SHARED_FIRST;
+        lock.l_len = divSize;
+        if( unixFileLock(pFile, &lock)==(-1) ){
+          tErrno = errno;
+          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK);
+          if( IS_LOCK_ERROR(rc) ){
+            storeLastErrno(pFile, tErrno);
+          }
+          goto end_unlock;
+        }
+        lock.l_type = F_UNLCK;
+        lock.l_whence = SEEK_SET;
+        lock.l_start = SHARED_FIRST+divSize;
+        lock.l_len = SHARED_SIZE-divSize;
+        if( unixFileLock(pFile, &lock)==(-1) ){
+          tErrno = errno;
+          rc = SQLITE_IOERR_UNLOCK;
+          storeLastErrno(pFile, tErrno);
+          goto end_unlock;
+        }
+      }else
+#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
+      {
+        lock.l_type = F_RDLCK;
+        lock.l_whence = SEEK_SET;
+        lock.l_start = SHARED_FIRST;
+        lock.l_len = SHARED_SIZE;
+        if( unixFileLock(pFile, &lock) ){
+          /* In theory, the call to unixFileLock() cannot fail because another
+          ** process is holding an incompatible lock. If it does, this 
+          ** indicates that the other process is not following the locking
+          ** protocol. If this happens, return SQLITE_IOERR_RDLOCK. Returning
+          ** SQLITE_BUSY would confuse the upper layer (in practice it causes 
+          ** an assert to fail). */ 
+          rc = SQLITE_IOERR_RDLOCK;
+          storeLastErrno(pFile, errno);
+          goto end_unlock;
+        }
+      }
+    }
+    lock.l_type = F_UNLCK;
+    lock.l_whence = SEEK_SET;
+    lock.l_start = PENDING_BYTE;
+    lock.l_len = 2L;  assert( PENDING_BYTE+1==RESERVED_BYTE );
+    if( unixFileLock(pFile, &lock)==0 ){
+      pInode->eFileLock = SHARED_LOCK;
+    }else{
+      rc = SQLITE_IOERR_UNLOCK;
+      storeLastErrno(pFile, errno);
+      goto end_unlock;
+    }
+  }
+  if( eFileLock==NO_LOCK ){
+    /* Decrement the shared lock counter.  Release the lock using an
+    ** OS call only when all threads in this same process have released
+    ** the lock.
+    */
+    pInode->nShared--;
+    if( pInode->nShared==0 ){
+      lock.l_type = F_UNLCK;
+      lock.l_whence = SEEK_SET;
+      lock.l_start = lock.l_len = 0L;
+      if( unixFileLock(pFile, &lock)==0 ){
+        pInode->eFileLock = NO_LOCK;
+      }else{
+        rc = SQLITE_IOERR_UNLOCK;
+        storeLastErrno(pFile, errno);
+        pInode->eFileLock = NO_LOCK;
+        pFile->eFileLock = NO_LOCK;
+      }
+    }
+
+    /* Decrement the count of locks against this same file.  When the
+    ** count reaches zero, close any other file descriptors whose close
+    ** was deferred because of outstanding locks.
+    */
+    pInode->nLock--;
+    assert( pInode->nLock>=0 );
+    if( pInode->nLock==0 ){
+      closePendingFds(pFile);
+    }
+  }
+
+end_unlock:
+  unixLeaveMutex();
+  if( rc==SQLITE_OK ) pFile->eFileLock = eFileLock;
+  return rc;
+}
+
+/*
+** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+*/
+static int unixUnlock(sqlite3_file *id, int eFileLock){
+#if SQLITE_MAX_MMAP_SIZE>0
+  assert( eFileLock==SHARED_LOCK || ((unixFile *)id)->nFetchOut==0 );
+#endif
+  return posixUnlock(id, eFileLock, 0);
+}
+
+#if SQLITE_MAX_MMAP_SIZE>0
+static int unixMapfile(unixFile *pFd, i64 nByte);
+static void unixUnmapfile(unixFile *pFd);
+#endif
+
+/*
+** This function performs the parts of the "close file" operation 
+** common to all locking schemes. It closes the directory and file
+** handles, if they are valid, and sets all fields of the unixFile
+** structure to 0.
+**
+** It is *not* necessary to hold the mutex when this routine is called,
+** even on VxWorks.  A mutex will be acquired on VxWorks by the
+** vxworksReleaseFileId() routine.
+*/
+static int closeUnixFile(sqlite3_file *id){
+  unixFile *pFile = (unixFile*)id;
+#if SQLITE_MAX_MMAP_SIZE>0
+  unixUnmapfile(pFile);
+#endif
+  if( pFile->h>=0 ){
+    robust_close(pFile, pFile->h, __LINE__);
+    pFile->h = -1;
+  }
+#if OS_VXWORKS
+  if( pFile->pId ){
+    if( pFile->ctrlFlags & UNIXFILE_DELETE ){
+      osUnlink(pFile->pId->zCanonicalName);
+    }
+    vxworksReleaseFileId(pFile->pId);
+    pFile->pId = 0;
+  }
+#endif
+#ifdef SQLITE_UNLINK_AFTER_CLOSE
+  if( pFile->ctrlFlags & UNIXFILE_DELETE ){
+    osUnlink(pFile->zPath);
+    sqlite3_free(*(char**)&pFile->zPath);
+    pFile->zPath = 0;
+  }
+#endif
+  OSTRACE(("CLOSE   %-3d\n", pFile->h));
+  OpenCounter(-1);
+  sqlite3_free(pFile->pUnused);
+  memset(pFile, 0, sizeof(unixFile));
+  return SQLITE_OK;
+}
+
+/*
+** Close a file.
+*/
+static int unixClose(sqlite3_file *id){
+  int rc = SQLITE_OK;
+  unixFile *pFile = (unixFile *)id;
+  verifyDbFile(pFile);
+  unixUnlock(id, NO_LOCK);
+  unixEnterMutex();
+
+  /* unixFile.pInode is always valid here. Otherwise, a different close
+  ** routine (e.g. nolockClose()) would be called instead.
+  */
+  assert( pFile->pInode->nLock>0 || pFile->pInode->bProcessLock==0 );
+  if( ALWAYS(pFile->pInode) && pFile->pInode->nLock ){
+    /* If there are outstanding locks, do not actually close the file just
+    ** yet because that would clear those locks.  Instead, add the file
+    ** descriptor to pInode->pUnused list.  It will be automatically closed 
+    ** when the last lock is cleared.
+    */
+    setPendingFd(pFile);
+  }
+  releaseInodeInfo(pFile);
+  rc = closeUnixFile(id);
+  unixLeaveMutex();
+  return rc;
+}
+
+/************** End of the posix advisory lock implementation *****************
+******************************************************************************/
+
+/******************************************************************************
+****************************** No-op Locking **********************************
+**
+** Of the various locking implementations available, this is by far the
+** simplest:  locking is ignored.  No attempt is made to lock the database
+** file for reading or writing.
+**
+** This locking mode is appropriate for use on read-only databases
+** (ex: databases that are burned into CD-ROM, for example.)  It can
+** also be used if the application employs some external mechanism to
+** prevent simultaneous access of the same database by two or more
+** database connections.  But there is a serious risk of database
+** corruption if this locking mode is used in situations where multiple
+** database connections are accessing the same database file at the same
+** time and one or more of those connections are writing.
+*/
+
+static int nolockCheckReservedLock(sqlite3_file *NotUsed, int *pResOut){
+  UNUSED_PARAMETER(NotUsed);
+  *pResOut = 0;
+  return SQLITE_OK;
+}
+static int nolockLock(sqlite3_file *NotUsed, int NotUsed2){
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  return SQLITE_OK;
+}
+static int nolockUnlock(sqlite3_file *NotUsed, int NotUsed2){
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  return SQLITE_OK;
+}
+
+/*
+** Close the file.
+*/
+static int nolockClose(sqlite3_file *id) {
+  return closeUnixFile(id);
+}
+
+/******************* End of the no-op lock implementation *********************
+******************************************************************************/
+
+/******************************************************************************
+************************* Begin dot-file Locking ******************************
+**
+** The dotfile locking implementation uses the existence of separate lock
+** files (really a directory) to control access to the database.  This works
+** on just about every filesystem imaginable.  But there are serious downsides:
+**
+**    (1)  There is zero concurrency.  A single reader blocks all other
+**         connections from reading or writing the database.
+**
+**    (2)  An application crash or power loss can leave stale lock files
+**         sitting around that need to be cleared manually.
+**
+** Nevertheless, a dotlock is an appropriate locking mode for use if no
+** other locking strategy is available.
+**
+** Dotfile locking works by creating a subdirectory in the same directory as
+** the database and with the same name but with a ".lock" extension added.
+** The existence of a lock directory implies an EXCLUSIVE lock.  All other
+** lock types (SHARED, RESERVED, PENDING) are mapped into EXCLUSIVE.
+*/
+
+/*
+** The file suffix added to the data base filename in order to create the
+** lock directory.
+*/
+#define DOTLOCK_SUFFIX ".lock"
+
+/*
+** This routine checks if there is a RESERVED lock held on the specified
+** file by this or any other process. If such a lock is held, set *pResOut
+** to a non-zero value otherwise *pResOut is set to zero.  The return value
+** is set to SQLITE_OK unless an I/O error occurs during lock checking.
+**
+** In dotfile locking, either a lock exists or it does not.  So in this
+** variation of CheckReservedLock(), *pResOut is set to true if any lock
+** is held on the file and false if the file is unlocked.
+*/
+static int dotlockCheckReservedLock(sqlite3_file *id, int *pResOut) {
+  int rc = SQLITE_OK;
+  int reserved = 0;
+  unixFile *pFile = (unixFile*)id;
+
+  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
+  
+  assert( pFile );
+  reserved = osAccess((const char*)pFile->lockingContext, 0)==0;
+  OSTRACE(("TEST WR-LOCK %d %d %d (dotlock)\n", pFile->h, rc, reserved));
+  *pResOut = reserved;
+  return rc;
+}
+
+/*
+** Lock the file with the lock specified by parameter eFileLock - one
+** of the following:
+**
+**     (1) SHARED_LOCK
+**     (2) RESERVED_LOCK
+**     (3) PENDING_LOCK
+**     (4) EXCLUSIVE_LOCK
+**
+** Sometimes when requesting one lock state, additional lock states
+** are inserted in between.  The locking might fail on one of the later
+** transitions leaving the lock state different from what it started but
+** still short of its goal.  The following chart shows the allowed
+** transitions and the inserted intermediate states:
+**
+**    UNLOCKED -> SHARED
+**    SHARED -> RESERVED
+**    SHARED -> (PENDING) -> EXCLUSIVE
+**    RESERVED -> (PENDING) -> EXCLUSIVE
+**    PENDING -> EXCLUSIVE
+**
+** This routine will only increase a lock.  Use the sqlite3OsUnlock()
+** routine to lower a locking level.
+**
+** With dotfile locking, we really only support state (4): EXCLUSIVE.
+** But we track the other locking levels internally.
+*/
+static int dotlockLock(sqlite3_file *id, int eFileLock) {
+  unixFile *pFile = (unixFile*)id;
+  char *zLockFile = (char *)pFile->lockingContext;
+  int rc = SQLITE_OK;
+
+
+  /* If we have any lock, then the lock file already exists.  All we have
+  ** to do is adjust our internal record of the lock level.
+  */
+  if( pFile->eFileLock > NO_LOCK ){
+    pFile->eFileLock = eFileLock;
+    /* Always update the timestamp on the old file */
+#ifdef HAVE_UTIME
+    utime(zLockFile, NULL);
+#else
+    utimes(zLockFile, NULL);
+#endif
+    return SQLITE_OK;
+  }
+  
+  /* grab an exclusive lock */
+  rc = osMkdir(zLockFile, 0777);
+  if( rc<0 ){
+    /* failed to open/create the lock directory */
+    int tErrno = errno;
+    if( EEXIST == tErrno ){
+      rc = SQLITE_BUSY;
+    } else {
+      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
+      if( rc!=SQLITE_BUSY ){
+        storeLastErrno(pFile, tErrno);
+      }
+    }
+    return rc;
+  } 
+  
+  /* got it, set the type and return ok */
+  pFile->eFileLock = eFileLock;
+  return rc;
+}
+
+/*
+** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+**
+** When the locking level reaches NO_LOCK, delete the lock file.
+*/
+static int dotlockUnlock(sqlite3_file *id, int eFileLock) {
+  unixFile *pFile = (unixFile*)id;
+  char *zLockFile = (char *)pFile->lockingContext;
+  int rc;
+
+  assert( pFile );
+  OSTRACE(("UNLOCK  %d %d was %d pid=%d (dotlock)\n", pFile->h, eFileLock,
+           pFile->eFileLock, osGetpid(0)));
+  assert( eFileLock<=SHARED_LOCK );
+  
+  /* no-op if possible */
+  if( pFile->eFileLock==eFileLock ){
+    return SQLITE_OK;
+  }
+
+  /* To downgrade to shared, simply update our internal notion of the
+  ** lock state.  No need to mess with the file on disk.
+  */
+  if( eFileLock==SHARED_LOCK ){
+    pFile->eFileLock = SHARED_LOCK;
+    return SQLITE_OK;
+  }
+  
+  /* To fully unlock the database, delete the lock file */
+  assert( eFileLock==NO_LOCK );
+  rc = osRmdir(zLockFile);
+  if( rc<0 ){
+    int tErrno = errno;
+    if( tErrno==ENOENT ){
+      rc = SQLITE_OK;
+    }else{
+      rc = SQLITE_IOERR_UNLOCK;
+      storeLastErrno(pFile, tErrno);
+    }
+    return rc; 
+  }
+  pFile->eFileLock = NO_LOCK;
+  return SQLITE_OK;
+}
+
+/*
+** Close a file.  Make sure the lock has been released before closing.
+*/
+static int dotlockClose(sqlite3_file *id) {
+  unixFile *pFile = (unixFile*)id;
+  assert( id!=0 );
+  dotlockUnlock(id, NO_LOCK);
+  sqlite3_free(pFile->lockingContext);
+  return closeUnixFile(id);
+}
+/****************** End of the dot-file lock implementation *******************
+******************************************************************************/
+
+/******************************************************************************
+************************** Begin flock Locking ********************************
+**
+** Use the flock() system call to do file locking.
+**
+** flock() locking is like dot-file locking in that the various
+** fine-grain locking levels supported by SQLite are collapsed into
+** a single exclusive lock.  In other words, SHARED, RESERVED, and
+** PENDING locks are the same thing as an EXCLUSIVE lock.  SQLite
+** still works when you do this, but concurrency is reduced since
+** only a single process can be reading the database at a time.
+**
+** Omit this section if SQLITE_ENABLE_LOCKING_STYLE is turned off
+*/
+#if SQLITE_ENABLE_LOCKING_STYLE
+
+/*
+** Retry flock() calls that fail with EINTR
+*/
+#ifdef EINTR
+static int robust_flock(int fd, int op){
+  int rc;
+  do{ rc = flock(fd,op); }while( rc<0 && errno==EINTR );
+  return rc;
+}
+#else
+# define robust_flock(a,b) flock(a,b)
+#endif
+     
+
+/*
+** This routine checks if there is a RESERVED lock held on the specified
+** file by this or any other process. If such a lock is held, set *pResOut
+** to a non-zero value otherwise *pResOut is set to zero.  The return value
+** is set to SQLITE_OK unless an I/O error occurs during lock checking.
+*/
+static int flockCheckReservedLock(sqlite3_file *id, int *pResOut){
+  int rc = SQLITE_OK;
+  int reserved = 0;
+  unixFile *pFile = (unixFile*)id;
+  
+  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
+  
+  assert( pFile );
+  
+  /* Check if a thread in this process holds such a lock */
+  if( pFile->eFileLock>SHARED_LOCK ){
+    reserved = 1;
+  }
+  
+  /* Otherwise see if some other process holds it. */
+  if( !reserved ){
+    /* attempt to get the lock */
+    int lrc = robust_flock(pFile->h, LOCK_EX | LOCK_NB);
+    if( !lrc ){
+      /* got the lock, unlock it */
+      lrc = robust_flock(pFile->h, LOCK_UN);
+      if ( lrc ) {
+        int tErrno = errno;
+        /* unlock failed with an error */
+        lrc = SQLITE_IOERR_UNLOCK; 
+        storeLastErrno(pFile, tErrno);
+        rc = lrc;
+      }
+    } else {
+      int tErrno = errno;
+      reserved = 1;
+      /* someone else might have it reserved */
+      lrc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK); 
+      if( IS_LOCK_ERROR(lrc) ){
+        storeLastErrno(pFile, tErrno);
+        rc = lrc;
+      }
+    }
+  }
+  OSTRACE(("TEST WR-LOCK %d %d %d (flock)\n", pFile->h, rc, reserved));
+
+#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS
+  if( (rc & SQLITE_IOERR) == SQLITE_IOERR ){
+    rc = SQLITE_OK;
+    reserved=1;
+  }
+#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */
+  *pResOut = reserved;
+  return rc;
+}
+
+/*
+** Lock the file with the lock specified by parameter eFileLock - one
+** of the following:
+**
+**     (1) SHARED_LOCK
+**     (2) RESERVED_LOCK
+**     (3) PENDING_LOCK
+**     (4) EXCLUSIVE_LOCK
+**
+** Sometimes when requesting one lock state, additional lock states
+** are inserted in between.  The locking might fail on one of the later
+** transitions leaving the lock state different from what it started but
+** still short of its goal.  The following chart shows the allowed
+** transitions and the inserted intermediate states:
+**
+**    UNLOCKED -> SHARED
+**    SHARED -> RESERVED
+**    SHARED -> (PENDING) -> EXCLUSIVE
+**    RESERVED -> (PENDING) -> EXCLUSIVE
+**    PENDING -> EXCLUSIVE
+**
+** flock() only really support EXCLUSIVE locks.  We track intermediate
+** lock states in the sqlite3_file structure, but all locks SHARED or
+** above are really EXCLUSIVE locks and exclude all other processes from
+** access the file.
+**
+** This routine will only increase a lock.  Use the sqlite3OsUnlock()
+** routine to lower a locking level.
+*/
+static int flockLock(sqlite3_file *id, int eFileLock) {
+  int rc = SQLITE_OK;
+  unixFile *pFile = (unixFile*)id;
+
+  assert( pFile );
+
+  /* if we already have a lock, it is exclusive.  
+  ** Just adjust level and punt on outta here. */
+  if (pFile->eFileLock > NO_LOCK) {
+    pFile->eFileLock = eFileLock;
+    return SQLITE_OK;
+  }
+  
+  /* grab an exclusive lock */
+  
+  if (robust_flock(pFile->h, LOCK_EX | LOCK_NB)) {
+    int tErrno = errno;
+    /* didn't get, must be busy */
+    rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
+    if( IS_LOCK_ERROR(rc) ){
+      storeLastErrno(pFile, tErrno);
+    }
+  } else {
+    /* got it, set the type and return ok */
+    pFile->eFileLock = eFileLock;
+  }
+  OSTRACE(("LOCK    %d %s %s (flock)\n", pFile->h, azFileLock(eFileLock), 
+           rc==SQLITE_OK ? "ok" : "failed"));
+#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS
+  if( (rc & SQLITE_IOERR) == SQLITE_IOERR ){
+    rc = SQLITE_BUSY;
+  }
+#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */
+  return rc;
+}
+
+
+/*
+** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+*/
+static int flockUnlock(sqlite3_file *id, int eFileLock) {
+  unixFile *pFile = (unixFile*)id;
+  
+  assert( pFile );
+  OSTRACE(("UNLOCK  %d %d was %d pid=%d (flock)\n", pFile->h, eFileLock,
+           pFile->eFileLock, osGetpid(0)));
+  assert( eFileLock<=SHARED_LOCK );
+  
+  /* no-op if possible */
+  if( pFile->eFileLock==eFileLock ){
+    return SQLITE_OK;
+  }
+  
+  /* shared can just be set because we always have an exclusive */
+  if (eFileLock==SHARED_LOCK) {
+    pFile->eFileLock = eFileLock;
+    return SQLITE_OK;
+  }
+  
+  /* no, really, unlock. */
+  if( robust_flock(pFile->h, LOCK_UN) ){
+#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS
+    return SQLITE_OK;
+#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */
+    return SQLITE_IOERR_UNLOCK;
+  }else{
+    pFile->eFileLock = NO_LOCK;
+    return SQLITE_OK;
+  }
+}
+
+/*
+** Close a file.
+*/
+static int flockClose(sqlite3_file *id) {
+  assert( id!=0 );
+  flockUnlock(id, NO_LOCK);
+  return closeUnixFile(id);
+}
+
+#endif /* SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORK */
+
+/******************* End of the flock lock implementation *********************
+******************************************************************************/
+
+/******************************************************************************
+************************ Begin Named Semaphore Locking ************************
+**
+** Named semaphore locking is only supported on VxWorks.
+**
+** Semaphore locking is like dot-lock and flock in that it really only
+** supports EXCLUSIVE locking.  Only a single process can read or write
+** the database file at a time.  This reduces potential concurrency, but
+** makes the lock implementation much easier.
+*/
+#if OS_VXWORKS
+
+/*
+** This routine checks if there is a RESERVED lock held on the specified
+** file by this or any other process. If such a lock is held, set *pResOut
+** to a non-zero value otherwise *pResOut is set to zero.  The return value
+** is set to SQLITE_OK unless an I/O error occurs during lock checking.
+*/
+static int semXCheckReservedLock(sqlite3_file *id, int *pResOut) {
+  int rc = SQLITE_OK;
+  int reserved = 0;
+  unixFile *pFile = (unixFile*)id;
+
+  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
+  
+  assert( pFile );
+
+  /* Check if a thread in this process holds such a lock */
+  if( pFile->eFileLock>SHARED_LOCK ){
+    reserved = 1;
+  }
+  
+  /* Otherwise see if some other process holds it. */
+  if( !reserved ){
+    sem_t *pSem = pFile->pInode->pSem;
+
+    if( sem_trywait(pSem)==-1 ){
+      int tErrno = errno;
+      if( EAGAIN != tErrno ){
+        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK);
+        storeLastErrno(pFile, tErrno);
+      } else {
+        /* someone else has the lock when we are in NO_LOCK */
+        reserved = (pFile->eFileLock < SHARED_LOCK);
+      }
+    }else{
+      /* we could have it if we want it */
+      sem_post(pSem);
+    }
+  }
+  OSTRACE(("TEST WR-LOCK %d %d %d (sem)\n", pFile->h, rc, reserved));
+
+  *pResOut = reserved;
+  return rc;
+}
+
+/*
+** Lock the file with the lock specified by parameter eFileLock - one
+** of the following:
+**
+**     (1) SHARED_LOCK
+**     (2) RESERVED_LOCK
+**     (3) PENDING_LOCK
+**     (4) EXCLUSIVE_LOCK
+**
+** Sometimes when requesting one lock state, additional lock states
+** are inserted in between.  The locking might fail on one of the later
+** transitions leaving the lock state different from what it started but
+** still short of its goal.  The following chart shows the allowed
+** transitions and the inserted intermediate states:
+**
+**    UNLOCKED -> SHARED
+**    SHARED -> RESERVED
+**    SHARED -> (PENDING) -> EXCLUSIVE
+**    RESERVED -> (PENDING) -> EXCLUSIVE
+**    PENDING -> EXCLUSIVE
+**
+** Semaphore locks only really support EXCLUSIVE locks.  We track intermediate
+** lock states in the sqlite3_file structure, but all locks SHARED or
+** above are really EXCLUSIVE locks and exclude all other processes from
+** access the file.
+**
+** This routine will only increase a lock.  Use the sqlite3OsUnlock()
+** routine to lower a locking level.
+*/
+static int semXLock(sqlite3_file *id, int eFileLock) {
+  unixFile *pFile = (unixFile*)id;
+  sem_t *pSem = pFile->pInode->pSem;
+  int rc = SQLITE_OK;
+
+  /* if we already have a lock, it is exclusive.  
+  ** Just adjust level and punt on outta here. */
+  if (pFile->eFileLock > NO_LOCK) {
+    pFile->eFileLock = eFileLock;
+    rc = SQLITE_OK;
+    goto sem_end_lock;
+  }
+  
+  /* lock semaphore now but bail out when already locked. */
+  if( sem_trywait(pSem)==-1 ){
+    rc = SQLITE_BUSY;
+    goto sem_end_lock;
+  }
+
+  /* got it, set the type and return ok */
+  pFile->eFileLock = eFileLock;
+
+ sem_end_lock:
+  return rc;
+}
+
+/*
+** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+*/
+static int semXUnlock(sqlite3_file *id, int eFileLock) {
+  unixFile *pFile = (unixFile*)id;
+  sem_t *pSem = pFile->pInode->pSem;
+
+  assert( pFile );
+  assert( pSem );
+  OSTRACE(("UNLOCK  %d %d was %d pid=%d (sem)\n", pFile->h, eFileLock,
+           pFile->eFileLock, osGetpid(0)));
+  assert( eFileLock<=SHARED_LOCK );
+  
+  /* no-op if possible */
+  if( pFile->eFileLock==eFileLock ){
+    return SQLITE_OK;
+  }
+  
+  /* shared can just be set because we always have an exclusive */
+  if (eFileLock==SHARED_LOCK) {
+    pFile->eFileLock = eFileLock;
+    return SQLITE_OK;
+  }
+  
+  /* no, really unlock. */
+  if ( sem_post(pSem)==-1 ) {
+    int rc, tErrno = errno;
+    rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
+    if( IS_LOCK_ERROR(rc) ){
+      storeLastErrno(pFile, tErrno);
+    }
+    return rc; 
+  }
+  pFile->eFileLock = NO_LOCK;
+  return SQLITE_OK;
+}
+
+/*
+ ** Close a file.
+ */
+static int semXClose(sqlite3_file *id) {
+  if( id ){
+    unixFile *pFile = (unixFile*)id;
+    semXUnlock(id, NO_LOCK);
+    assert( pFile );
+    unixEnterMutex();
+    releaseInodeInfo(pFile);
+    unixLeaveMutex();
+    closeUnixFile(id);
+  }
+  return SQLITE_OK;
+}
+
+#endif /* OS_VXWORKS */
+/*
+** Named semaphore locking is only available on VxWorks.
+**
+*************** End of the named semaphore lock implementation ****************
+******************************************************************************/
+
+
+/******************************************************************************
+*************************** Begin AFP Locking *********************************
+**
+** AFP is the Apple Filing Protocol.  AFP is a network filesystem found
+** on Apple Macintosh computers - both OS9 and OSX.
+**
+** Third-party implementations of AFP are available.  But this code here
+** only works on OSX.
+*/
+
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+/*
+** The afpLockingContext structure contains all afp lock specific state
+*/
+typedef struct afpLockingContext afpLockingContext;
+struct afpLockingContext {
+  int reserved;
+  const char *dbPath;             /* Name of the open file */
+};
+
+struct ByteRangeLockPB2
+{
+  unsigned long long offset;        /* offset to first byte to lock */
+  unsigned long long length;        /* nbr of bytes to lock */
+  unsigned long long retRangeStart; /* nbr of 1st byte locked if successful */
+  unsigned char unLockFlag;         /* 1 = unlock, 0 = lock */
+  unsigned char startEndFlag;       /* 1=rel to end of fork, 0=rel to start */
+  int fd;                           /* file desc to assoc this lock with */
+};
+
+#define afpfsByteRangeLock2FSCTL        _IOWR('z', 23, struct ByteRangeLockPB2)
+
+/*
+** This is a utility for setting or clearing a bit-range lock on an
+** AFP filesystem.
+** 
+** Return SQLITE_OK on success, SQLITE_BUSY on failure.
+*/
+static int afpSetLock(
+  const char *path,              /* Name of the file to be locked or unlocked */
+  unixFile *pFile,               /* Open file descriptor on path */
+  unsigned long long offset,     /* First byte to be locked */
+  unsigned long long length,     /* Number of bytes to lock */
+  int setLockFlag                /* True to set lock.  False to clear lock */
+){
+  struct ByteRangeLockPB2 pb;
+  int err;
+  
+  pb.unLockFlag = setLockFlag ? 0 : 1;
+  pb.startEndFlag = 0;
+  pb.offset = offset;
+  pb.length = length; 
+  pb.fd = pFile->h;
+  
+  OSTRACE(("AFPSETLOCK [%s] for %d%s in range %llx:%llx\n", 
+    (setLockFlag?"ON":"OFF"), pFile->h, (pb.fd==-1?"[testval-1]":""),
+    offset, length));
+  err = fsctl(path, afpfsByteRangeLock2FSCTL, &pb, 0);
+  if ( err==-1 ) {
+    int rc;
+    int tErrno = errno;
+    OSTRACE(("AFPSETLOCK failed to fsctl() '%s' %d %s\n",
+             path, tErrno, strerror(tErrno)));
+#ifdef SQLITE_IGNORE_AFP_LOCK_ERRORS
+    rc = SQLITE_BUSY;
+#else
+    rc = sqliteErrorFromPosixError(tErrno,
+                    setLockFlag ? SQLITE_IOERR_LOCK : SQLITE_IOERR_UNLOCK);
+#endif /* SQLITE_IGNORE_AFP_LOCK_ERRORS */
+    if( IS_LOCK_ERROR(rc) ){
+      storeLastErrno(pFile, tErrno);
+    }
+    return rc;
+  } else {
+    return SQLITE_OK;
+  }
+}
+
+/*
+** This routine checks if there is a RESERVED lock held on the specified
+** file by this or any other process. If such a lock is held, set *pResOut
+** to a non-zero value otherwise *pResOut is set to zero.  The return value
+** is set to SQLITE_OK unless an I/O error occurs during lock checking.
+*/
+static int afpCheckReservedLock(sqlite3_file *id, int *pResOut){
+  int rc = SQLITE_OK;
+  int reserved = 0;
+  unixFile *pFile = (unixFile*)id;
+  afpLockingContext *context;
+  
+  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
+  
+  assert( pFile );
+  context = (afpLockingContext *) pFile->lockingContext;
+  if( context->reserved ){
+    *pResOut = 1;
+    return SQLITE_OK;
+  }
+  unixEnterMutex(); /* Because pFile->pInode is shared across threads */
+  
+  /* Check if a thread in this process holds such a lock */
+  if( pFile->pInode->eFileLock>SHARED_LOCK ){
+    reserved = 1;
+  }
+  
+  /* Otherwise see if some other process holds it.
+   */
+  if( !reserved ){
+    /* lock the RESERVED byte */
+    int lrc = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1,1);  
+    if( SQLITE_OK==lrc ){
+      /* if we succeeded in taking the reserved lock, unlock it to restore
+      ** the original state */
+      lrc = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1, 0);
+    } else {
+      /* if we failed to get the lock then someone else must have it */
+      reserved = 1;
+    }
+    if( IS_LOCK_ERROR(lrc) ){
+      rc=lrc;
+    }
+  }
+  
+  unixLeaveMutex();
+  OSTRACE(("TEST WR-LOCK %d %d %d (afp)\n", pFile->h, rc, reserved));
+  
+  *pResOut = reserved;
+  return rc;
+}
+
+/*
+** Lock the file with the lock specified by parameter eFileLock - one
+** of the following:
+**
+**     (1) SHARED_LOCK
+**     (2) RESERVED_LOCK
+**     (3) PENDING_LOCK
+**     (4) EXCLUSIVE_LOCK
+**
+** Sometimes when requesting one lock state, additional lock states
+** are inserted in between.  The locking might fail on one of the later
+** transitions leaving the lock state different from what it started but
+** still short of its goal.  The following chart shows the allowed
+** transitions and the inserted intermediate states:
+**
+**    UNLOCKED -> SHARED
+**    SHARED -> RESERVED
+**    SHARED -> (PENDING) -> EXCLUSIVE
+**    RESERVED -> (PENDING) -> EXCLUSIVE
+**    PENDING -> EXCLUSIVE
+**
+** This routine will only increase a lock.  Use the sqlite3OsUnlock()
+** routine to lower a locking level.
+*/
+static int afpLock(sqlite3_file *id, int eFileLock){
+  int rc = SQLITE_OK;
+  unixFile *pFile = (unixFile*)id;
+  unixInodeInfo *pInode = pFile->pInode;
+  afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;
+  
+  assert( pFile );
+  OSTRACE(("LOCK    %d %s was %s(%s,%d) pid=%d (afp)\n", pFile->h,
+           azFileLock(eFileLock), azFileLock(pFile->eFileLock),
+           azFileLock(pInode->eFileLock), pInode->nShared , osGetpid(0)));
+
+  /* If there is already a lock of this type or more restrictive on the
+  ** unixFile, do nothing. Don't use the afp_end_lock: exit path, as
+  ** unixEnterMutex() hasn't been called yet.
+  */
+  if( pFile->eFileLock>=eFileLock ){
+    OSTRACE(("LOCK    %d %s ok (already held) (afp)\n", pFile->h,
+           azFileLock(eFileLock)));
+    return SQLITE_OK;
+  }
+
+  /* Make sure the locking sequence is correct
+  **  (1) We never move from unlocked to anything higher than shared lock.
+  **  (2) SQLite never explicitly requests a pendig lock.
+  **  (3) A shared lock is always held when a reserve lock is requested.
+  */
+  assert( pFile->eFileLock!=NO_LOCK || eFileLock==SHARED_LOCK );
+  assert( eFileLock!=PENDING_LOCK );
+  assert( eFileLock!=RESERVED_LOCK || pFile->eFileLock==SHARED_LOCK );
+  
+  /* This mutex is needed because pFile->pInode is shared across threads
+  */
+  unixEnterMutex();
+  pInode = pFile->pInode;
+
+  /* If some thread using this PID has a lock via a different unixFile*
+  ** handle that precludes the requested lock, return BUSY.
+  */
+  if( (pFile->eFileLock!=pInode->eFileLock && 
+       (pInode->eFileLock>=PENDING_LOCK || eFileLock>SHARED_LOCK))
+     ){
+    rc = SQLITE_BUSY;
+    goto afp_end_lock;
+  }
+  
+  /* If a SHARED lock is requested, and some thread using this PID already
+  ** has a SHARED or RESERVED lock, then increment reference counts and
+  ** return SQLITE_OK.
+  */
+  if( eFileLock==SHARED_LOCK && 
+     (pInode->eFileLock==SHARED_LOCK || pInode->eFileLock==RESERVED_LOCK) ){
+    assert( eFileLock==SHARED_LOCK );
+    assert( pFile->eFileLock==0 );
+    assert( pInode->nShared>0 );
+    pFile->eFileLock = SHARED_LOCK;
+    pInode->nShared++;
+    pInode->nLock++;
+    goto afp_end_lock;
+  }
+    
+  /* A PENDING lock is needed before acquiring a SHARED lock and before
+  ** acquiring an EXCLUSIVE lock.  For the SHARED lock, the PENDING will
+  ** be released.
+  */
+  if( eFileLock==SHARED_LOCK 
+      || (eFileLock==EXCLUSIVE_LOCK && pFile->eFileLock<PENDING_LOCK)
+  ){
+    int failed;
+    failed = afpSetLock(context->dbPath, pFile, PENDING_BYTE, 1, 1);
+    if (failed) {
+      rc = failed;
+      goto afp_end_lock;
+    }
+  }
+  
+  /* If control gets to this point, then actually go ahead and make
+  ** operating system calls for the specified lock.
+  */
+  if( eFileLock==SHARED_LOCK ){
+    int lrc1, lrc2, lrc1Errno = 0;
+    long lk, mask;
+    
+    assert( pInode->nShared==0 );
+    assert( pInode->eFileLock==0 );
+        
+    mask = (sizeof(long)==8) ? LARGEST_INT64 : 0x7fffffff;
+    /* Now get the read-lock SHARED_LOCK */
+    /* note that the quality of the randomness doesn't matter that much */
+    lk = random(); 
+    pInode->sharedByte = (lk & mask)%(SHARED_SIZE - 1);
+    lrc1 = afpSetLock(context->dbPath, pFile, 
+          SHARED_FIRST+pInode->sharedByte, 1, 1);
+    if( IS_LOCK_ERROR(lrc1) ){
+      lrc1Errno = pFile->lastErrno;
+    }
+    /* Drop the temporary PENDING lock */
+    lrc2 = afpSetLock(context->dbPath, pFile, PENDING_BYTE, 1, 0);
+    
+    if( IS_LOCK_ERROR(lrc1) ) {
+      storeLastErrno(pFile, lrc1Errno);
+      rc = lrc1;
+      goto afp_end_lock;
+    } else if( IS_LOCK_ERROR(lrc2) ){
+      rc = lrc2;
+      goto afp_end_lock;
+    } else if( lrc1 != SQLITE_OK ) {
+      rc = lrc1;
+    } else {
+      pFile->eFileLock = SHARED_LOCK;
+      pInode->nLock++;
+      pInode->nShared = 1;
+    }
+  }else if( eFileLock==EXCLUSIVE_LOCK && pInode->nShared>1 ){
+    /* We are trying for an exclusive lock but another thread in this
+     ** same process is still holding a shared lock. */
+    rc = SQLITE_BUSY;
+  }else{
+    /* The request was for a RESERVED or EXCLUSIVE lock.  It is
+    ** assumed that there is a SHARED or greater lock on the file
+    ** already.
+    */
+    int failed = 0;
+    assert( 0!=pFile->eFileLock );
+    if (eFileLock >= RESERVED_LOCK && pFile->eFileLock < RESERVED_LOCK) {
+        /* Acquire a RESERVED lock */
+        failed = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1,1);
+      if( !failed ){
+        context->reserved = 1;
+      }
+    }
+    if (!failed && eFileLock == EXCLUSIVE_LOCK) {
+      /* Acquire an EXCLUSIVE lock */
+        
+      /* Remove the shared lock before trying the range.  we'll need to 
+      ** reestablish the shared lock if we can't get the  afpUnlock
+      */
+      if( !(failed = afpSetLock(context->dbPath, pFile, SHARED_FIRST +
+                         pInode->sharedByte, 1, 0)) ){
+        int failed2 = SQLITE_OK;
+        /* now attemmpt to get the exclusive lock range */
+        failed = afpSetLock(context->dbPath, pFile, SHARED_FIRST, 
+                               SHARED_SIZE, 1);
+        if( failed && (failed2 = afpSetLock(context->dbPath, pFile, 
+                       SHARED_FIRST + pInode->sharedByte, 1, 1)) ){
+          /* Can't reestablish the shared lock.  Sqlite can't deal, this is
+          ** a critical I/O error
+          */
+          rc = ((failed & SQLITE_IOERR) == SQLITE_IOERR) ? failed2 : 
+               SQLITE_IOERR_LOCK;
+          goto afp_end_lock;
+        } 
+      }else{
+        rc = failed; 
+      }
+    }
+    if( failed ){
+      rc = failed;
+    }
+  }
+  
+  if( rc==SQLITE_OK ){
+    pFile->eFileLock = eFileLock;
+    pInode->eFileLock = eFileLock;
+  }else if( eFileLock==EXCLUSIVE_LOCK ){
+    pFile->eFileLock = PENDING_LOCK;
+    pInode->eFileLock = PENDING_LOCK;
+  }
+  
+afp_end_lock:
+  unixLeaveMutex();
+  OSTRACE(("LOCK    %d %s %s (afp)\n", pFile->h, azFileLock(eFileLock), 
+         rc==SQLITE_OK ? "ok" : "failed"));
+  return rc;
+}
+
+/*
+** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+*/
+static int afpUnlock(sqlite3_file *id, int eFileLock) {
+  int rc = SQLITE_OK;
+  unixFile *pFile = (unixFile*)id;
+  unixInodeInfo *pInode;
+  afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;
+  int skipShared = 0;
+#ifdef SQLITE_TEST
+  int h = pFile->h;
+#endif
+
+  assert( pFile );
+  OSTRACE(("UNLOCK  %d %d was %d(%d,%d) pid=%d (afp)\n", pFile->h, eFileLock,
+           pFile->eFileLock, pFile->pInode->eFileLock, pFile->pInode->nShared,
+           osGetpid(0)));
+
+  assert( eFileLock<=SHARED_LOCK );
+  if( pFile->eFileLock<=eFileLock ){
+    return SQLITE_OK;
+  }
+  unixEnterMutex();
+  pInode = pFile->pInode;
+  assert( pInode->nShared!=0 );
+  if( pFile->eFileLock>SHARED_LOCK ){
+    assert( pInode->eFileLock==pFile->eFileLock );
+    SimulateIOErrorBenign(1);
+    SimulateIOError( h=(-1) )
+    SimulateIOErrorBenign(0);
+    
+#ifdef SQLITE_DEBUG
+    /* When reducing a lock such that other processes can start
+    ** reading the database file again, make sure that the
+    ** transaction counter was updated if any part of the database
+    ** file changed.  If the transaction counter is not updated,
+    ** other connections to the same file might not realize that
+    ** the file has changed and hence might not know to flush their
+    ** cache.  The use of a stale cache can lead to database corruption.
+    */
+    assert( pFile->inNormalWrite==0
+           || pFile->dbUpdate==0
+           || pFile->transCntrChng==1 );
+    pFile->inNormalWrite = 0;
+#endif
+    
+    if( pFile->eFileLock==EXCLUSIVE_LOCK ){
+      rc = afpSetLock(context->dbPath, pFile, SHARED_FIRST, SHARED_SIZE, 0);
+      if( rc==SQLITE_OK && (eFileLock==SHARED_LOCK || pInode->nShared>1) ){
+        /* only re-establish the shared lock if necessary */
+        int sharedLockByte = SHARED_FIRST+pInode->sharedByte;
+        rc = afpSetLock(context->dbPath, pFile, sharedLockByte, 1, 1);
+      } else {
+        skipShared = 1;
+      }
+    }
+    if( rc==SQLITE_OK && pFile->eFileLock>=PENDING_LOCK ){
+      rc = afpSetLock(context->dbPath, pFile, PENDING_BYTE, 1, 0);
+    } 
+    if( rc==SQLITE_OK && pFile->eFileLock>=RESERVED_LOCK && context->reserved ){
+      rc = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1, 0);
+      if( !rc ){ 
+        context->reserved = 0; 
+      }
+    }
+    if( rc==SQLITE_OK && (eFileLock==SHARED_LOCK || pInode->nShared>1)){
+      pInode->eFileLock = SHARED_LOCK;
+    }
+  }
+  if( rc==SQLITE_OK && eFileLock==NO_LOCK ){
+
+    /* Decrement the shared lock counter.  Release the lock using an
+    ** OS call only when all threads in this same process have released
+    ** the lock.
+    */
+    unsigned long long sharedLockByte = SHARED_FIRST+pInode->sharedByte;
+    pInode->nShared--;
+    if( pInode->nShared==0 ){
+      SimulateIOErrorBenign(1);
+      SimulateIOError( h=(-1) )
+      SimulateIOErrorBenign(0);
+      if( !skipShared ){
+        rc = afpSetLock(context->dbPath, pFile, sharedLockByte, 1, 0);
+      }
+      if( !rc ){
+        pInode->eFileLock = NO_LOCK;
+        pFile->eFileLock = NO_LOCK;
+      }
+    }
+    if( rc==SQLITE_OK ){
+      pInode->nLock--;
+      assert( pInode->nLock>=0 );
+      if( pInode->nLock==0 ){
+        closePendingFds(pFile);
+      }
+    }
+  }
+  
+  unixLeaveMutex();
+  if( rc==SQLITE_OK ) pFile->eFileLock = eFileLock;
+  return rc;
+}
+
+/*
+** Close a file & cleanup AFP specific locking context 
+*/
+static int afpClose(sqlite3_file *id) {
+  int rc = SQLITE_OK;
+  unixFile *pFile = (unixFile*)id;
+  assert( id!=0 );
+  afpUnlock(id, NO_LOCK);
+  unixEnterMutex();
+  if( pFile->pInode && pFile->pInode->nLock ){
+    /* If there are outstanding locks, do not actually close the file just
+    ** yet because that would clear those locks.  Instead, add the file
+    ** descriptor to pInode->aPending.  It will be automatically closed when
+    ** the last lock is cleared.
+    */
+    setPendingFd(pFile);
+  }
+  releaseInodeInfo(pFile);
+  sqlite3_free(pFile->lockingContext);
+  rc = closeUnixFile(id);
+  unixLeaveMutex();
+  return rc;
+}
+
+#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
+/*
+** The code above is the AFP lock implementation.  The code is specific
+** to MacOSX and does not work on other unix platforms.  No alternative
+** is available.  If you don't compile for a mac, then the "unix-afp"
+** VFS is not available.
+**
+********************* End of the AFP lock implementation **********************
+******************************************************************************/
+
+/******************************************************************************
+*************************** Begin NFS Locking ********************************/
+
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+/*
+ ** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
+ ** must be either NO_LOCK or SHARED_LOCK.
+ **
+ ** If the locking level of the file descriptor is already at or below
+ ** the requested locking level, this routine is a no-op.
+ */
+static int nfsUnlock(sqlite3_file *id, int eFileLock){
+  return posixUnlock(id, eFileLock, 1);
+}
+
+#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
+/*
+** The code above is the NFS lock implementation.  The code is specific
+** to MacOSX and does not work on other unix platforms.  No alternative
+** is available.  
+**
+********************* End of the NFS lock implementation **********************
+******************************************************************************/
+
+/******************************************************************************
+**************** Non-locking sqlite3_file methods *****************************
+**
+** The next division contains implementations for all methods of the 
+** sqlite3_file object other than the locking methods.  The locking
+** methods were defined in divisions above (one locking method per
+** division).  Those methods that are common to all locking modes
+** are gather together into this division.
+*/
+
+/*
+** Seek to the offset passed as the second argument, then read cnt 
+** bytes into pBuf. Return the number of bytes actually read.
+**
+** NB:  If you define USE_PREAD or USE_PREAD64, then it might also
+** be necessary to define _XOPEN_SOURCE to be 500.  This varies from
+** one system to another.  Since SQLite does not define USE_PREAD
+** in any form by default, we will not attempt to define _XOPEN_SOURCE.
+** See tickets #2741 and #2681.
+**
+** To avoid stomping the errno value on a failed read the lastErrno value
+** is set before returning.
+*/
+static int seekAndRead(unixFile *id, sqlite3_int64 offset, void *pBuf, int cnt){
+  int got;
+  int prior = 0;
+#if (!defined(USE_PREAD) && !defined(USE_PREAD64))
+  i64 newOffset;
+#endif
+  TIMER_START;
+  assert( cnt==(cnt&0x1ffff) );
+  assert( id->h>2 );
+  do{
+#if defined(USE_PREAD)
+    got = osPread(id->h, pBuf, cnt, offset);
+    SimulateIOError( got = -1 );
+#elif defined(USE_PREAD64)
+    got = osPread64(id->h, pBuf, cnt, offset);
+    SimulateIOError( got = -1 );
+#else
+    newOffset = lseek(id->h, offset, SEEK_SET);
+    SimulateIOError( newOffset = -1 );
+    if( newOffset<0 ){
+      storeLastErrno((unixFile*)id, errno);
+      return -1;
+    }
+    got = osRead(id->h, pBuf, cnt);
+#endif
+    if( got==cnt ) break;
+    if( got<0 ){
+      if( errno==EINTR ){ got = 1; continue; }
+      prior = 0;
+      storeLastErrno((unixFile*)id,  errno);
+      break;
+    }else if( got>0 ){
+      cnt -= got;
+      offset += got;
+      prior += got;
+      pBuf = (void*)(got + (char*)pBuf);
+    }
+  }while( got>0 );
+  TIMER_END;
+  OSTRACE(("READ    %-3d %5d %7lld %llu\n",
+            id->h, got+prior, offset-prior, TIMER_ELAPSED));
+  return got+prior;
+}
+
+/*
+** Read data from a file into a buffer.  Return SQLITE_OK if all
+** bytes were read successfully and SQLITE_IOERR if anything goes
+** wrong.
+*/
+static int unixRead(
+  sqlite3_file *id, 
+  void *pBuf, 
+  int amt,
+  sqlite3_int64 offset
+){
+  unixFile *pFile = (unixFile *)id;
+  int got;
+  assert( id );
+  assert( offset>=0 );
+  assert( amt>0 );
+
+  /* If this is a database file (not a journal, master-journal or temp
+  ** file), the bytes in the locking range should never be read or written. */
+#if 0
+  assert( pFile->pUnused==0
+       || offset>=PENDING_BYTE+512
+       || offset+amt<=PENDING_BYTE 
+  );
+#endif
+
+#if SQLITE_MAX_MMAP_SIZE>0
+  /* Deal with as much of this read request as possible by transfering
+  ** data from the memory mapping using memcpy().  */
+  if( offset<pFile->mmapSize ){
+    if( offset+amt <= pFile->mmapSize ){
+      memcpy(pBuf, &((u8 *)(pFile->pMapRegion))[offset], amt);
+      return SQLITE_OK;
+    }else{
+      int nCopy = pFile->mmapSize - offset;
+      memcpy(pBuf, &((u8 *)(pFile->pMapRegion))[offset], nCopy);
+      pBuf = &((u8 *)pBuf)[nCopy];
+      amt -= nCopy;
+      offset += nCopy;
+    }
+  }
+#endif
+
+  got = seekAndRead(pFile, offset, pBuf, amt);
+  if( got==amt ){
+    return SQLITE_OK;
+  }else if( got<0 ){
+    /* lastErrno set by seekAndRead */
+    return SQLITE_IOERR_READ;
+  }else{
+    storeLastErrno(pFile, 0);   /* not a system error */
+    /* Unread parts of the buffer must be zero-filled */
+    memset(&((char*)pBuf)[got], 0, amt-got);
+    return SQLITE_IOERR_SHORT_READ;
+  }
+}
+
+/*
+** Attempt to seek the file-descriptor passed as the first argument to
+** absolute offset iOff, then attempt to write nBuf bytes of data from
+** pBuf to it. If an error occurs, return -1 and set *piErrno. Otherwise, 
+** return the actual number of bytes written (which may be less than
+** nBuf).
+*/
+static int seekAndWriteFd(
+  int fd,                         /* File descriptor to write to */
+  i64 iOff,                       /* File offset to begin writing at */
+  const void *pBuf,               /* Copy data from this buffer to the file */
+  int nBuf,                       /* Size of buffer pBuf in bytes */
+  int *piErrno                    /* OUT: Error number if error occurs */
+){
+  int rc = 0;                     /* Value returned by system call */
+
+  assert( nBuf==(nBuf&0x1ffff) );
+  assert( fd>2 );
+  assert( piErrno!=0 );
+  nBuf &= 0x1ffff;
+  TIMER_START;
+
+#if defined(USE_PREAD)
+  do{ rc = (int)osPwrite(fd, pBuf, nBuf, iOff); }while( rc<0 && errno==EINTR );
+#elif defined(USE_PREAD64)
+  do{ rc = (int)osPwrite64(fd, pBuf, nBuf, iOff);}while( rc<0 && errno==EINTR);
+#else
+  do{
+    i64 iSeek = lseek(fd, iOff, SEEK_SET);
+    SimulateIOError( iSeek = -1 );
+    if( iSeek<0 ){
+      rc = -1;
+      break;
+    }
+    rc = osWrite(fd, pBuf, nBuf);
+  }while( rc<0 && errno==EINTR );
+#endif
+
+  TIMER_END;
+  OSTRACE(("WRITE   %-3d %5d %7lld %llu\n", fd, rc, iOff, TIMER_ELAPSED));
+
+  if( rc<0 ) *piErrno = errno;
+  return rc;
+}
+
+
+/*
+** Seek to the offset in id->offset then read cnt bytes into pBuf.
+** Return the number of bytes actually read.  Update the offset.
+**
+** To avoid stomping the errno value on a failed write the lastErrno value
+** is set before returning.
+*/
+static int seekAndWrite(unixFile *id, i64 offset, const void *pBuf, int cnt){
+  return seekAndWriteFd(id->h, offset, pBuf, cnt, &id->lastErrno);
+}
+
+
+/*
+** Write data from a buffer into a file.  Return SQLITE_OK on success
+** or some other error code on failure.
+*/
+static int unixWrite(
+  sqlite3_file *id, 
+  const void *pBuf, 
+  int amt,
+  sqlite3_int64 offset 
+){
+  unixFile *pFile = (unixFile*)id;
+  int wrote = 0;
+  assert( id );
+  assert( amt>0 );
+
+  /* If this is a database file (not a journal, master-journal or temp
+  ** file), the bytes in the locking range should never be read or written. */
+#if 0
+  assert( pFile->pUnused==0
+       || offset>=PENDING_BYTE+512
+       || offset+amt<=PENDING_BYTE 
+  );
+#endif
+
+#ifdef SQLITE_DEBUG
+  /* If we are doing a normal write to a database file (as opposed to
+  ** doing a hot-journal rollback or a write to some file other than a
+  ** normal database file) then record the fact that the database
+  ** has changed.  If the transaction counter is modified, record that
+  ** fact too.
+  */
+  if( pFile->inNormalWrite ){
+    pFile->dbUpdate = 1;  /* The database has been modified */
+    if( offset<=24 && offset+amt>=27 ){
+      int rc;
+      char oldCntr[4];
+      SimulateIOErrorBenign(1);
+      rc = seekAndRead(pFile, 24, oldCntr, 4);
+      SimulateIOErrorBenign(0);
+      if( rc!=4 || memcmp(oldCntr, &((char*)pBuf)[24-offset], 4)!=0 ){
+        pFile->transCntrChng = 1;  /* The transaction counter has changed */
+      }
+    }
+  }
+#endif
+
+#if defined(SQLITE_MMAP_READWRITE) && SQLITE_MAX_MMAP_SIZE>0
+  /* Deal with as much of this write request as possible by transfering
+  ** data from the memory mapping using memcpy().  */
+  if( offset<pFile->mmapSize ){
+    if( offset+amt <= pFile->mmapSize ){
+      memcpy(&((u8 *)(pFile->pMapRegion))[offset], pBuf, amt);
+      return SQLITE_OK;
+    }else{
+      int nCopy = pFile->mmapSize - offset;
+      memcpy(&((u8 *)(pFile->pMapRegion))[offset], pBuf, nCopy);
+      pBuf = &((u8 *)pBuf)[nCopy];
+      amt -= nCopy;
+      offset += nCopy;
+    }
+  }
+#endif
+ 
+  while( (wrote = seekAndWrite(pFile, offset, pBuf, amt))<amt && wrote>0 ){
+    amt -= wrote;
+    offset += wrote;
+    pBuf = &((char*)pBuf)[wrote];
+  }
+  SimulateIOError(( wrote=(-1), amt=1 ));
+  SimulateDiskfullError(( wrote=0, amt=1 ));
+
+  if( amt>wrote ){
+    if( wrote<0 && pFile->lastErrno!=ENOSPC ){
+      /* lastErrno set by seekAndWrite */
+      return SQLITE_IOERR_WRITE;
+    }else{
+      storeLastErrno(pFile, 0); /* not a system error */
+      return SQLITE_FULL;
+    }
+  }
+
+  return SQLITE_OK;
+}
+
+#ifdef SQLITE_TEST
+/*
+** Count the number of fullsyncs and normal syncs.  This is used to test
+** that syncs and fullsyncs are occurring at the right times.
+*/
+SQLITE_API int sqlite3_sync_count = 0;
+SQLITE_API int sqlite3_fullsync_count = 0;
+#endif
+
+/*
+** We do not trust systems to provide a working fdatasync().  Some do.
+** Others do no.  To be safe, we will stick with the (slightly slower)
+** fsync(). If you know that your system does support fdatasync() correctly,
+** then simply compile with -Dfdatasync=fdatasync or -DHAVE_FDATASYNC
+*/
+#if !defined(fdatasync) && !HAVE_FDATASYNC
+# define fdatasync fsync
+#endif
+
+/*
+** Define HAVE_FULLFSYNC to 0 or 1 depending on whether or not
+** the F_FULLFSYNC macro is defined.  F_FULLFSYNC is currently
+** only available on Mac OS X.  But that could change.
+*/
+#ifdef F_FULLFSYNC
+# define HAVE_FULLFSYNC 1
+#else
+# define HAVE_FULLFSYNC 0
+#endif
+
+
+/*
+** The fsync() system call does not work as advertised on many
+** unix systems.  The following procedure is an attempt to make
+** it work better.
+**
+** The SQLITE_NO_SYNC macro disables all fsync()s.  This is useful
+** for testing when we want to run through the test suite quickly.
+** You are strongly advised *not* to deploy with SQLITE_NO_SYNC
+** enabled, however, since with SQLITE_NO_SYNC enabled, an OS crash
+** or power failure will likely corrupt the database file.
+**
+** SQLite sets the dataOnly flag if the size of the file is unchanged.
+** The idea behind dataOnly is that it should only write the file content
+** to disk, not the inode.  We only set dataOnly if the file size is 
+** unchanged since the file size is part of the inode.  However, 
+** Ted Ts'o tells us that fdatasync() will also write the inode if the
+** file size has changed.  The only real difference between fdatasync()
+** and fsync(), Ted tells us, is that fdatasync() will not flush the
+** inode if the mtime or owner or other inode attributes have changed.
+** We only care about the file size, not the other file attributes, so
+** as far as SQLite is concerned, an fdatasync() is always adequate.
+** So, we always use fdatasync() if it is available, regardless of
+** the value of the dataOnly flag.
+*/
+static int full_fsync(int fd, int fullSync, int dataOnly){
+  int rc;
+
+  /* The following "ifdef/elif/else/" block has the same structure as
+  ** the one below. It is replicated here solely to avoid cluttering 
+  ** up the real code with the UNUSED_PARAMETER() macros.
+  */
+#ifdef SQLITE_NO_SYNC
+  UNUSED_PARAMETER(fd);
+  UNUSED_PARAMETER(fullSync);
+  UNUSED_PARAMETER(dataOnly);
+#elif HAVE_FULLFSYNC
+  UNUSED_PARAMETER(dataOnly);
+#else
+  UNUSED_PARAMETER(fullSync);
+  UNUSED_PARAMETER(dataOnly);
+#endif
+
+  /* Record the number of times that we do a normal fsync() and 
+  ** FULLSYNC.  This is used during testing to verify that this procedure
+  ** gets called with the correct arguments.
+  */
+#ifdef SQLITE_TEST
+  if( fullSync ) sqlite3_fullsync_count++;
+  sqlite3_sync_count++;
+#endif
+
+  /* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a
+  ** no-op.  But go ahead and call fstat() to validate the file
+  ** descriptor as we need a method to provoke a failure during
+  ** coverate testing.
+  */
+#ifdef SQLITE_NO_SYNC
+  {
+    struct stat buf;
+    rc = osFstat(fd, &buf);
+  }
+#elif HAVE_FULLFSYNC
+  if( fullSync ){
+    rc = osFcntl(fd, F_FULLFSYNC, 0);
+  }else{
+    rc = 1;
+  }
+  /* If the FULLFSYNC failed, fall back to attempting an fsync().
+  ** It shouldn't be possible for fullfsync to fail on the local 
+  ** file system (on OSX), so failure indicates that FULLFSYNC
+  ** isn't supported for this file system. So, attempt an fsync 
+  ** and (for now) ignore the overhead of a superfluous fcntl call.  
+  ** It'd be better to detect fullfsync support once and avoid 
+  ** the fcntl call every time sync is called.
+  */
+  if( rc ) rc = fsync(fd);
+
+#elif defined(__APPLE__)
+  /* fdatasync() on HFS+ doesn't yet flush the file size if it changed correctly
+  ** so currently we default to the macro that redefines fdatasync to fsync
+  */
+  rc = fsync(fd);
+#else 
+  rc = fdatasync(fd);
+#if OS_VXWORKS
+  if( rc==-1 && errno==ENOTSUP ){
+    rc = fsync(fd);
+  }
+#endif /* OS_VXWORKS */
+#endif /* ifdef SQLITE_NO_SYNC elif HAVE_FULLFSYNC */
+
+  if( OS_VXWORKS && rc!= -1 ){
+    rc = 0;
+  }
+  return rc;
+}
+
+/*
+** Open a file descriptor to the directory containing file zFilename.
+** If successful, *pFd is set to the opened file descriptor and
+** SQLITE_OK is returned. If an error occurs, either SQLITE_NOMEM
+** or SQLITE_CANTOPEN is returned and *pFd is set to an undefined
+** value.
+**
+** The directory file descriptor is used for only one thing - to
+** fsync() a directory to make sure file creation and deletion events
+** are flushed to disk.  Such fsyncs are not needed on newer
+** journaling filesystems, but are required on older filesystems.
+**
+** This routine can be overridden using the xSetSysCall interface.
+** The ability to override this routine was added in support of the
+** chromium sandbox.  Opening a directory is a security risk (we are
+** told) so making it overrideable allows the chromium sandbox to
+** replace this routine with a harmless no-op.  To make this routine
+** a no-op, replace it with a stub that returns SQLITE_OK but leaves
+** *pFd set to a negative number.
+**
+** If SQLITE_OK is returned, the caller is responsible for closing
+** the file descriptor *pFd using close().
+*/
+static int openDirectory(const char *zFilename, int *pFd){
+  int ii;
+  int fd = -1;
+  char zDirname[MAX_PATHNAME+1];
+
+  sqlite3_snprintf(MAX_PATHNAME, zDirname, "%s", zFilename);
+  for(ii=(int)strlen(zDirname); ii>0 && zDirname[ii]!='/'; ii--);
+  if( ii>0 ){
+    zDirname[ii] = '\0';
+  }else{
+    if( zDirname[0]!='/' ) zDirname[0] = '.';
+    zDirname[1] = 0;
+  }
+  fd = robust_open(zDirname, O_RDONLY|O_BINARY, 0);
+  if( fd>=0 ){
+    OSTRACE(("OPENDIR %-3d %s\n", fd, zDirname));
+  }
+  *pFd = fd;
+  if( fd>=0 ) return SQLITE_OK;
+  return unixLogError(SQLITE_CANTOPEN_BKPT, "openDirectory", zDirname);
+}
+
+/*
+** Make sure all writes to a particular file are committed to disk.
+**
+** If dataOnly==0 then both the file itself and its metadata (file
+** size, access time, etc) are synced.  If dataOnly!=0 then only the
+** file data is synced.
+**
+** Under Unix, also make sure that the directory entry for the file
+** has been created by fsync-ing the directory that contains the file.
+** If we do not do this and we encounter a power failure, the directory
+** entry for the journal might not exist after we reboot.  The next
+** SQLite to access the file will not know that the journal exists (because
+** the directory entry for the journal was never created) and the transaction
+** will not roll back - possibly leading to database corruption.
+*/
+static int unixSync(sqlite3_file *id, int flags){
+  int rc;
+  unixFile *pFile = (unixFile*)id;
+
+  int isDataOnly = (flags&SQLITE_SYNC_DATAONLY);
+  int isFullsync = (flags&0x0F)==SQLITE_SYNC_FULL;
+
+  /* Check that one of SQLITE_SYNC_NORMAL or FULL was passed */
+  assert((flags&0x0F)==SQLITE_SYNC_NORMAL
+      || (flags&0x0F)==SQLITE_SYNC_FULL
+  );
+
+  /* Unix cannot, but some systems may return SQLITE_FULL from here. This
+  ** line is to test that doing so does not cause any problems.
+  */
+  SimulateDiskfullError( return SQLITE_FULL );
+
+  assert( pFile );
+  OSTRACE(("SYNC    %-3d\n", pFile->h));
+  rc = full_fsync(pFile->h, isFullsync, isDataOnly);
+  SimulateIOError( rc=1 );
+  if( rc ){
+    storeLastErrno(pFile, errno);
+    return unixLogError(SQLITE_IOERR_FSYNC, "full_fsync", pFile->zPath);
+  }
+
+  /* Also fsync the directory containing the file if the DIRSYNC flag
+  ** is set.  This is a one-time occurrence.  Many systems (examples: AIX)
+  ** are unable to fsync a directory, so ignore errors on the fsync.
+  */
+  if( pFile->ctrlFlags & UNIXFILE_DIRSYNC ){
+    int dirfd;
+    OSTRACE(("DIRSYNC %s (have_fullfsync=%d fullsync=%d)\n", pFile->zPath,
+            HAVE_FULLFSYNC, isFullsync));
+    rc = osOpenDirectory(pFile->zPath, &dirfd);
+    if( rc==SQLITE_OK ){
+      full_fsync(dirfd, 0, 0);
+      robust_close(pFile, dirfd, __LINE__);
+    }else{
+      assert( rc==SQLITE_CANTOPEN );
+      rc = SQLITE_OK;
+    }
+    pFile->ctrlFlags &= ~UNIXFILE_DIRSYNC;
+  }
+  return rc;
+}
+
+/*
+** Truncate an open file to a specified size
+*/
+static int unixTruncate(sqlite3_file *id, i64 nByte){
+  unixFile *pFile = (unixFile *)id;
+  int rc;
+  assert( pFile );
+  SimulateIOError( return SQLITE_IOERR_TRUNCATE );
+
+  /* If the user has configured a chunk-size for this file, truncate the
+  ** file so that it consists of an integer number of chunks (i.e. the
+  ** actual file size after the operation may be larger than the requested
+  ** size).
+  */
+  if( pFile->szChunk>0 ){
+    nByte = ((nByte + pFile->szChunk - 1)/pFile->szChunk) * pFile->szChunk;
+  }
+
+  rc = robust_ftruncate(pFile->h, nByte);
+  if( rc ){
+    storeLastErrno(pFile, errno);
+    return unixLogError(SQLITE_IOERR_TRUNCATE, "ftruncate", pFile->zPath);
+  }else{
+#ifdef SQLITE_DEBUG
+    /* If we are doing a normal write to a database file (as opposed to
+    ** doing a hot-journal rollback or a write to some file other than a
+    ** normal database file) and we truncate the file to zero length,
+    ** that effectively updates the change counter.  This might happen
+    ** when restoring a database using the backup API from a zero-length
+    ** source.
+    */
+    if( pFile->inNormalWrite && nByte==0 ){
+      pFile->transCntrChng = 1;
+    }
+#endif
+
+#if SQLITE_MAX_MMAP_SIZE>0
+    /* If the file was just truncated to a size smaller than the currently
+    ** mapped region, reduce the effective mapping size as well. SQLite will
+    ** use read() and write() to access data beyond this point from now on.  
+    */
+    if( nByte<pFile->mmapSize ){
+      pFile->mmapSize = nByte;
+    }
+#endif
+
+    return SQLITE_OK;
+  }
+}
+
+/*
+** Determine the current size of a file in bytes
+*/
+static int unixFileSize(sqlite3_file *id, i64 *pSize){
+  int rc;
+  struct stat buf;
+  assert( id );
+  rc = osFstat(((unixFile*)id)->h, &buf);
+  SimulateIOError( rc=1 );
+  if( rc!=0 ){
+    storeLastErrno((unixFile*)id, errno);
+    return SQLITE_IOERR_FSTAT;
+  }
+  *pSize = buf.st_size;
+
+  /* When opening a zero-size database, the findInodeInfo() procedure
+  ** writes a single byte into that file in order to work around a bug
+  ** in the OS-X msdos filesystem.  In order to avoid problems with upper
+  ** layers, we need to report this file size as zero even though it is
+  ** really 1.   Ticket #3260.
+  */
+  if( *pSize==1 ) *pSize = 0;
+
+
+  return SQLITE_OK;
+}
+
+#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
+/*
+** Handler for proxy-locking file-control verbs.  Defined below in the
+** proxying locking division.
+*/
+static int proxyFileControl(sqlite3_file*,int,void*);
+#endif
+
+/* 
+** This function is called to handle the SQLITE_FCNTL_SIZE_HINT 
+** file-control operation.  Enlarge the database to nBytes in size
+** (rounded up to the next chunk-size).  If the database is already
+** nBytes or larger, this routine is a no-op.
+*/
+static int fcntlSizeHint(unixFile *pFile, i64 nByte){
+  if( pFile->szChunk>0 ){
+    i64 nSize;                    /* Required file size */
+    struct stat buf;              /* Used to hold return values of fstat() */
+   
+    if( osFstat(pFile->h, &buf) ){
+      return SQLITE_IOERR_FSTAT;
+    }
+
+    nSize = ((nByte+pFile->szChunk-1) / pFile->szChunk) * pFile->szChunk;
+    if( nSize>(i64)buf.st_size ){
+
+#if defined(HAVE_POSIX_FALLOCATE) && HAVE_POSIX_FALLOCATE
+      /* The code below is handling the return value of osFallocate() 
+      ** correctly. posix_fallocate() is defined to "returns zero on success, 
+      ** or an error number on  failure". See the manpage for details. */
+      int err;
+      do{
+        err = osFallocate(pFile->h, buf.st_size, nSize-buf.st_size);
+      }while( err==EINTR );
+      if( err ) return SQLITE_IOERR_WRITE;
+#else
+      /* If the OS does not have posix_fallocate(), fake it. Write a 
+      ** single byte to the last byte in each block that falls entirely
+      ** within the extended region. Then, if required, a single byte
+      ** at offset (nSize-1), to set the size of the file correctly.
+      ** This is a similar technique to that used by glibc on systems
+      ** that do not have a real fallocate() call.
+      */
+      int nBlk = buf.st_blksize;  /* File-system block size */
+      int nWrite = 0;             /* Number of bytes written by seekAndWrite */
+      i64 iWrite;                 /* Next offset to write to */
+
+      iWrite = (buf.st_size/nBlk)*nBlk + nBlk - 1;
+      assert( iWrite>=buf.st_size );
+      assert( ((iWrite+1)%nBlk)==0 );
+      for(/*no-op*/; iWrite<nSize+nBlk-1; iWrite+=nBlk ){
+        if( iWrite>=nSize ) iWrite = nSize - 1;
+        nWrite = seekAndWrite(pFile, iWrite, "", 1);
+        if( nWrite!=1 ) return SQLITE_IOERR_WRITE;
+      }
+#endif
+    }
+  }
+
+#if SQLITE_MAX_MMAP_SIZE>0
+  if( pFile->mmapSizeMax>0 && nByte>pFile->mmapSize ){
+    int rc;
+    if( pFile->szChunk<=0 ){
+      if( robust_ftruncate(pFile->h, nByte) ){
+        storeLastErrno(pFile, errno);
+        return unixLogError(SQLITE_IOERR_TRUNCATE, "ftruncate", pFile->zPath);
+      }
+    }
+
+    rc = unixMapfile(pFile, nByte);
+    return rc;
+  }
+#endif
+
+  return SQLITE_OK;
+}
+
+/*
+** If *pArg is initially negative then this is a query.  Set *pArg to
+** 1 or 0 depending on whether or not bit mask of pFile->ctrlFlags is set.
+**
+** If *pArg is 0 or 1, then clear or set the mask bit of pFile->ctrlFlags.
+*/
+static void unixModeBit(unixFile *pFile, unsigned char mask, int *pArg){
+  if( *pArg<0 ){
+    *pArg = (pFile->ctrlFlags & mask)!=0;
+  }else if( (*pArg)==0 ){
+    pFile->ctrlFlags &= ~mask;
+  }else{
+    pFile->ctrlFlags |= mask;
+  }
+}
+
+/* Forward declaration */
+static int unixGetTempname(int nBuf, char *zBuf);
+
+/*
+** Information and control of an open file handle.
+*/
+static int unixFileControl(sqlite3_file *id, int op, void *pArg){
+  unixFile *pFile = (unixFile*)id;
+  switch( op ){
+    case SQLITE_FCNTL_LOCKSTATE: {
+      *(int*)pArg = pFile->eFileLock;
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_LAST_ERRNO: {
+      *(int*)pArg = pFile->lastErrno;
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_CHUNK_SIZE: {
+      pFile->szChunk = *(int *)pArg;
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_SIZE_HINT: {
+      int rc;
+      SimulateIOErrorBenign(1);
+      rc = fcntlSizeHint(pFile, *(i64 *)pArg);
+      SimulateIOErrorBenign(0);
+      return rc;
+    }
+    case SQLITE_FCNTL_PERSIST_WAL: {
+      unixModeBit(pFile, UNIXFILE_PERSIST_WAL, (int*)pArg);
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_POWERSAFE_OVERWRITE: {
+      unixModeBit(pFile, UNIXFILE_PSOW, (int*)pArg);
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_VFSNAME: {
+      *(char**)pArg = sqlite3_mprintf("%s", pFile->pVfs->zName);
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_TEMPFILENAME: {
+      char *zTFile = sqlite3_malloc64( pFile->pVfs->mxPathname );
+      if( zTFile ){
+        unixGetTempname(pFile->pVfs->mxPathname, zTFile);
+        *(char**)pArg = zTFile;
+      }
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_HAS_MOVED: {
+      *(int*)pArg = fileHasMoved(pFile);
+      return SQLITE_OK;
+    }
+#if SQLITE_MAX_MMAP_SIZE>0
+    case SQLITE_FCNTL_MMAP_SIZE: {
+      i64 newLimit = *(i64*)pArg;
+      int rc = SQLITE_OK;
+      if( newLimit>sqlite3GlobalConfig.mxMmap ){
+        newLimit = sqlite3GlobalConfig.mxMmap;
+      }
+      *(i64*)pArg = pFile->mmapSizeMax;
+      if( newLimit>=0 && newLimit!=pFile->mmapSizeMax && pFile->nFetchOut==0 ){
+        pFile->mmapSizeMax = newLimit;
+        if( pFile->mmapSize>0 ){
+          unixUnmapfile(pFile);
+          rc = unixMapfile(pFile, -1);
+        }
+      }
+      return rc;
+    }
+#endif
+#ifdef SQLITE_DEBUG
+    /* The pager calls this method to signal that it has done
+    ** a rollback and that the database is therefore unchanged and
+    ** it hence it is OK for the transaction change counter to be
+    ** unchanged.
+    */
+    case SQLITE_FCNTL_DB_UNCHANGED: {
+      ((unixFile*)id)->dbUpdate = 0;
+      return SQLITE_OK;
+    }
+#endif
+#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
+    case SQLITE_FCNTL_SET_LOCKPROXYFILE:
+    case SQLITE_FCNTL_GET_LOCKPROXYFILE: {
+      return proxyFileControl(id,op,pArg);
+    }
+#endif /* SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__) */
+  }
+  return SQLITE_NOTFOUND;
+}
+
+/*
+** Return the sector size in bytes of the underlying block device for
+** the specified file. This is almost always 512 bytes, but may be
+** larger for some devices.
+**
+** SQLite code assumes this function cannot fail. It also assumes that
+** if two files are created in the same file-system directory (i.e.
+** a database and its journal file) that the sector size will be the
+** same for both.
+*/
+#ifndef __QNXNTO__ 
+static int unixSectorSize(sqlite3_file *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  return SQLITE_DEFAULT_SECTOR_SIZE;
+}
+#endif
+
+/*
+** The following version of unixSectorSize() is optimized for QNX.
+*/
+#ifdef __QNXNTO__
+#include <sys/dcmd_blk.h>
+#include <sys/statvfs.h>
+static int unixSectorSize(sqlite3_file *id){
+  unixFile *pFile = (unixFile*)id;
+  if( pFile->sectorSize == 0 ){
+    struct statvfs fsInfo;
+       
+    /* Set defaults for non-supported filesystems */
+    pFile->sectorSize = SQLITE_DEFAULT_SECTOR_SIZE;
+    pFile->deviceCharacteristics = 0;
+    if( fstatvfs(pFile->h, &fsInfo) == -1 ) {
+      return pFile->sectorSize;
+    }
+
+    if( !strcmp(fsInfo.f_basetype, "tmp") ) {
+      pFile->sectorSize = fsInfo.f_bsize;
+      pFile->deviceCharacteristics =
+        SQLITE_IOCAP_ATOMIC4K |       /* All ram filesystem writes are atomic */
+        SQLITE_IOCAP_SAFE_APPEND |    /* growing the file does not occur until
+                                      ** the write succeeds */
+        SQLITE_IOCAP_SEQUENTIAL |     /* The ram filesystem has no write behind
+                                      ** so it is ordered */
+        0;
+    }else if( strstr(fsInfo.f_basetype, "etfs") ){
+      pFile->sectorSize = fsInfo.f_bsize;
+      pFile->deviceCharacteristics =
+        /* etfs cluster size writes are atomic */
+        (pFile->sectorSize / 512 * SQLITE_IOCAP_ATOMIC512) |
+        SQLITE_IOCAP_SAFE_APPEND |    /* growing the file does not occur until
+                                      ** the write succeeds */
+        SQLITE_IOCAP_SEQUENTIAL |     /* The ram filesystem has no write behind
+                                      ** so it is ordered */
+        0;
+    }else if( !strcmp(fsInfo.f_basetype, "qnx6") ){
+      pFile->sectorSize = fsInfo.f_bsize;
+      pFile->deviceCharacteristics =
+        SQLITE_IOCAP_ATOMIC |         /* All filesystem writes are atomic */
+        SQLITE_IOCAP_SAFE_APPEND |    /* growing the file does not occur until
+                                      ** the write succeeds */
+        SQLITE_IOCAP_SEQUENTIAL |     /* The ram filesystem has no write behind
+                                      ** so it is ordered */
+        0;
+    }else if( !strcmp(fsInfo.f_basetype, "qnx4") ){
+      pFile->sectorSize = fsInfo.f_bsize;
+      pFile->deviceCharacteristics =
+        /* full bitset of atomics from max sector size and smaller */
+        ((pFile->sectorSize / 512 * SQLITE_IOCAP_ATOMIC512) << 1) - 2 |
+        SQLITE_IOCAP_SEQUENTIAL |     /* The ram filesystem has no write behind
+                                      ** so it is ordered */
+        0;
+    }else if( strstr(fsInfo.f_basetype, "dos") ){
+      pFile->sectorSize = fsInfo.f_bsize;
+      pFile->deviceCharacteristics =
+        /* full bitset of atomics from max sector size and smaller */
+        ((pFile->sectorSize / 512 * SQLITE_IOCAP_ATOMIC512) << 1) - 2 |
+        SQLITE_IOCAP_SEQUENTIAL |     /* The ram filesystem has no write behind
+                                      ** so it is ordered */
+        0;
+    }else{
+      pFile->deviceCharacteristics =
+        SQLITE_IOCAP_ATOMIC512 |      /* blocks are atomic */
+        SQLITE_IOCAP_SAFE_APPEND |    /* growing the file does not occur until
+                                      ** the write succeeds */
+        0;
+    }
+  }
+  /* Last chance verification.  If the sector size isn't a multiple of 512
+  ** then it isn't valid.*/
+  if( pFile->sectorSize % 512 != 0 ){
+    pFile->deviceCharacteristics = 0;
+    pFile->sectorSize = SQLITE_DEFAULT_SECTOR_SIZE;
+  }
+  return pFile->sectorSize;
+}
+#endif /* __QNXNTO__ */
+
+/*
+** Return the device characteristics for the file.
+**
+** This VFS is set up to return SQLITE_IOCAP_POWERSAFE_OVERWRITE by default.
+** However, that choice is controversial since technically the underlying
+** file system does not always provide powersafe overwrites.  (In other
+** words, after a power-loss event, parts of the file that were never
+** written might end up being altered.)  However, non-PSOW behavior is very,
+** very rare.  And asserting PSOW makes a large reduction in the amount
+** of required I/O for journaling, since a lot of padding is eliminated.
+**  Hence, while POWERSAFE_OVERWRITE is on by default, there is a file-control
+** available to turn it off and URI query parameter available to turn it off.
+*/
+static int unixDeviceCharacteristics(sqlite3_file *id){
+  unixFile *p = (unixFile*)id;
+  int rc = 0;
+#ifdef __QNXNTO__
+  if( p->sectorSize==0 ) unixSectorSize(id);
+  rc = p->deviceCharacteristics;
+#endif
+  if( p->ctrlFlags & UNIXFILE_PSOW ){
+    rc |= SQLITE_IOCAP_POWERSAFE_OVERWRITE;
+  }
+  return rc;
+}
+
+#if !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0
+
+/*
+** Return the system page size.
+**
+** This function should not be called directly by other code in this file. 
+** Instead, it should be called via macro osGetpagesize().
+*/
+static int unixGetpagesize(void){
+#if OS_VXWORKS
+  return 1024;
+#elif defined(_BSD_SOURCE)
+  return getpagesize();
+#else
+  return (int)sysconf(_SC_PAGESIZE);
+#endif
+}
+
+#endif /* !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0 */
+
+#ifndef SQLITE_OMIT_WAL
+
+/*
+** Object used to represent an shared memory buffer.  
+**
+** When multiple threads all reference the same wal-index, each thread
+** has its own unixShm object, but they all point to a single instance
+** of this unixShmNode object.  In other words, each wal-index is opened
+** only once per process.
+**
+** Each unixShmNode object is connected to a single unixInodeInfo object.
+** We could coalesce this object into unixInodeInfo, but that would mean
+** every open file that does not use shared memory (in other words, most
+** open files) would have to carry around this extra information.  So
+** the unixInodeInfo object contains a pointer to this unixShmNode object
+** and the unixShmNode object is created only when needed.
+**
+** unixMutexHeld() must be true when creating or destroying
+** this object or while reading or writing the following fields:
+**
+**      nRef
+**
+** The following fields are read-only after the object is created:
+** 
+**      fid
+**      zFilename
+**
+** Either unixShmNode.mutex must be held or unixShmNode.nRef==0 and
+** unixMutexHeld() is true when reading or writing any other field
+** in this structure.
+*/
+struct unixShmNode {
+  unixInodeInfo *pInode;     /* unixInodeInfo that owns this SHM node */
+  sqlite3_mutex *mutex;      /* Mutex to access this object */
+  char *zFilename;           /* Name of the mmapped file */
+  int h;                     /* Open file descriptor */
+  int szRegion;              /* Size of shared-memory regions */
+  u16 nRegion;               /* Size of array apRegion */
+  u8 isReadonly;             /* True if read-only */
+  char **apRegion;           /* Array of mapped shared-memory regions */
+  int nRef;                  /* Number of unixShm objects pointing to this */
+  unixShm *pFirst;           /* All unixShm objects pointing to this */
+#ifdef SQLITE_DEBUG
+  u8 exclMask;               /* Mask of exclusive locks held */
+  u8 sharedMask;             /* Mask of shared locks held */
+  u8 nextShmId;              /* Next available unixShm.id value */
+#endif
+};
+
+/*
+** Structure used internally by this VFS to record the state of an
+** open shared memory connection.
+**
+** The following fields are initialized when this object is created and
+** are read-only thereafter:
+**
+**    unixShm.pFile
+**    unixShm.id
+**
+** All other fields are read/write.  The unixShm.pFile->mutex must be held
+** while accessing any read/write fields.
+*/
+struct unixShm {
+  unixShmNode *pShmNode;     /* The underlying unixShmNode object */
+  unixShm *pNext;            /* Next unixShm with the same unixShmNode */
+  u8 hasMutex;               /* True if holding the unixShmNode mutex */
+  u8 id;                     /* Id of this connection within its unixShmNode */
+  u16 sharedMask;            /* Mask of shared locks held */
+  u16 exclMask;              /* Mask of exclusive locks held */
+};
+
+/*
+** Constants used for locking
+*/
+#define UNIX_SHM_BASE   ((22+SQLITE_SHM_NLOCK)*4)         /* first lock byte */
+#define UNIX_SHM_DMS    (UNIX_SHM_BASE+SQLITE_SHM_NLOCK)  /* deadman switch */
+
+/*
+** Apply posix advisory locks for all bytes from ofst through ofst+n-1.
+**
+** Locks block if the mask is exactly UNIX_SHM_C and are non-blocking
+** otherwise.
+*/
+static int unixShmSystemLock(
+  unixFile *pFile,       /* Open connection to the WAL file */
+  int lockType,          /* F_UNLCK, F_RDLCK, or F_WRLCK */
+  int ofst,              /* First byte of the locking range */
+  int n                  /* Number of bytes to lock */
+){
+  unixShmNode *pShmNode; /* Apply locks to this open shared-memory segment */
+  struct flock f;        /* The posix advisory locking structure */
+  int rc = SQLITE_OK;    /* Result code form fcntl() */
+
+  /* Access to the unixShmNode object is serialized by the caller */
+  pShmNode = pFile->pInode->pShmNode;
+  assert( sqlite3_mutex_held(pShmNode->mutex) || pShmNode->nRef==0 );
+
+  /* Shared locks never span more than one byte */
+  assert( n==1 || lockType!=F_RDLCK );
+
+  /* Locks are within range */
+  assert( n>=1 && n<=SQLITE_SHM_NLOCK );
+
+  if( pShmNode->h>=0 ){
+    /* Initialize the locking parameters */
+    memset(&f, 0, sizeof(f));
+    f.l_type = lockType;
+    f.l_whence = SEEK_SET;
+    f.l_start = ofst;
+    f.l_len = n;
+
+    rc = osFcntl(pShmNode->h, F_SETLK, &f);
+    rc = (rc!=(-1)) ? SQLITE_OK : SQLITE_BUSY;
+  }
+
+  /* Update the global lock state and do debug tracing */
+#ifdef SQLITE_DEBUG
+  { u16 mask;
+  OSTRACE(("SHM-LOCK "));
+  mask = ofst>31 ? 0xffff : (1<<(ofst+n)) - (1<<ofst);
+  if( rc==SQLITE_OK ){
+    if( lockType==F_UNLCK ){
+      OSTRACE(("unlock %d ok", ofst));
+      pShmNode->exclMask &= ~mask;
+      pShmNode->sharedMask &= ~mask;
+    }else if( lockType==F_RDLCK ){
+      OSTRACE(("read-lock %d ok", ofst));
+      pShmNode->exclMask &= ~mask;
+      pShmNode->sharedMask |= mask;
+    }else{
+      assert( lockType==F_WRLCK );
+      OSTRACE(("write-lock %d ok", ofst));
+      pShmNode->exclMask |= mask;
+      pShmNode->sharedMask &= ~mask;
+    }
+  }else{
+    if( lockType==F_UNLCK ){
+      OSTRACE(("unlock %d failed", ofst));
+    }else if( lockType==F_RDLCK ){
+      OSTRACE(("read-lock failed"));
+    }else{
+      assert( lockType==F_WRLCK );
+      OSTRACE(("write-lock %d failed", ofst));
+    }
+  }
+  OSTRACE((" - afterwards %03x,%03x\n",
+           pShmNode->sharedMask, pShmNode->exclMask));
+  }
+#endif
+
+  return rc;        
+}
+
+/*
+** Return the minimum number of 32KB shm regions that should be mapped at
+** a time, assuming that each mapping must be an integer multiple of the
+** current system page-size.
+**
+** Usually, this is 1. The exception seems to be systems that are configured
+** to use 64KB pages - in this case each mapping must cover at least two
+** shm regions.
+*/
+static int unixShmRegionPerMap(void){
+  int shmsz = 32*1024;            /* SHM region size */
+  int pgsz = osGetpagesize();   /* System page size */
+  assert( ((pgsz-1)&pgsz)==0 );   /* Page size must be a power of 2 */
+  if( pgsz<shmsz ) return 1;
+  return pgsz/shmsz;
+}
+
+/*
+** Purge the unixShmNodeList list of all entries with unixShmNode.nRef==0.
+**
+** This is not a VFS shared-memory method; it is a utility function called
+** by VFS shared-memory methods.
+*/
+static void unixShmPurge(unixFile *pFd){
+  unixShmNode *p = pFd->pInode->pShmNode;
+  assert( unixMutexHeld() );
+  if( p && ALWAYS(p->nRef==0) ){
+    int nShmPerMap = unixShmRegionPerMap();
+    int i;
+    assert( p->pInode==pFd->pInode );
+    sqlite3_mutex_free(p->mutex);
+    for(i=0; i<p->nRegion; i+=nShmPerMap){
+      if( p->h>=0 ){
+        osMunmap(p->apRegion[i], p->szRegion);
+      }else{
+        sqlite3_free(p->apRegion[i]);
+      }
+    }
+    sqlite3_free(p->apRegion);
+    if( p->h>=0 ){
+      robust_close(pFd, p->h, __LINE__);
+      p->h = -1;
+    }
+    p->pInode->pShmNode = 0;
+    sqlite3_free(p);
+  }
+}
+
+/*
+** Open a shared-memory area associated with open database file pDbFd.  
+** This particular implementation uses mmapped files.
+**
+** The file used to implement shared-memory is in the same directory
+** as the open database file and has the same name as the open database
+** file with the "-shm" suffix added.  For example, if the database file
+** is "/home/user1/config.db" then the file that is created and mmapped
+** for shared memory will be called "/home/user1/config.db-shm".  
+**
+** Another approach to is to use files in /dev/shm or /dev/tmp or an
+** some other tmpfs mount. But if a file in a different directory
+** from the database file is used, then differing access permissions
+** or a chroot() might cause two different processes on the same
+** database to end up using different files for shared memory - 
+** meaning that their memory would not really be shared - resulting
+** in database corruption.  Nevertheless, this tmpfs file usage
+** can be enabled at compile-time using -DSQLITE_SHM_DIRECTORY="/dev/shm"
+** or the equivalent.  The use of the SQLITE_SHM_DIRECTORY compile-time
+** option results in an incompatible build of SQLite;  builds of SQLite
+** that with differing SQLITE_SHM_DIRECTORY settings attempt to use the
+** same database file at the same time, database corruption will likely
+** result. The SQLITE_SHM_DIRECTORY compile-time option is considered
+** "unsupported" and may go away in a future SQLite release.
+**
+** When opening a new shared-memory file, if no other instances of that
+** file are currently open, in this process or in other processes, then
+** the file must be truncated to zero length or have its header cleared.
+**
+** If the original database file (pDbFd) is using the "unix-excl" VFS
+** that means that an exclusive lock is held on the database file and
+** that no other processes are able to read or write the database.  In
+** that case, we do not really need shared memory.  No shared memory
+** file is created.  The shared memory will be simulated with heap memory.
+*/
+static int unixOpenSharedMemory(unixFile *pDbFd){
+  struct unixShm *p = 0;          /* The connection to be opened */
+  struct unixShmNode *pShmNode;   /* The underlying mmapped file */
+  int rc;                         /* Result code */
+  unixInodeInfo *pInode;          /* The inode of fd */
+  char *zShmFilename;             /* Name of the file used for SHM */
+  int nShmFilename;               /* Size of the SHM filename in bytes */
+
+  /* Allocate space for the new unixShm object. */
+  p = sqlite3_malloc64( sizeof(*p) );
+  if( p==0 ) return SQLITE_NOMEM_BKPT;
+  memset(p, 0, sizeof(*p));
+  assert( pDbFd->pShm==0 );
+
+  /* Check to see if a unixShmNode object already exists. Reuse an existing
+  ** one if present. Create a new one if necessary.
+  */
+  unixEnterMutex();
+  pInode = pDbFd->pInode;
+  pShmNode = pInode->pShmNode;
+  if( pShmNode==0 ){
+    struct stat sStat;                 /* fstat() info for database file */
+#ifndef SQLITE_SHM_DIRECTORY
+    const char *zBasePath = pDbFd->zPath;
+#endif
+
+    /* Call fstat() to figure out the permissions on the database file. If
+    ** a new *-shm file is created, an attempt will be made to create it
+    ** with the same permissions.
+    */
+    if( osFstat(pDbFd->h, &sStat) ){
+      rc = SQLITE_IOERR_FSTAT;
+      goto shm_open_err;
+    }
+
+#ifdef SQLITE_SHM_DIRECTORY
+    nShmFilename = sizeof(SQLITE_SHM_DIRECTORY) + 31;
+#else
+    nShmFilename = 6 + (int)strlen(zBasePath);
+#endif
+    pShmNode = sqlite3_malloc64( sizeof(*pShmNode) + nShmFilename );
+    if( pShmNode==0 ){
+      rc = SQLITE_NOMEM_BKPT;
+      goto shm_open_err;
+    }
+    memset(pShmNode, 0, sizeof(*pShmNode)+nShmFilename);
+    zShmFilename = pShmNode->zFilename = (char*)&pShmNode[1];
+#ifdef SQLITE_SHM_DIRECTORY
+    sqlite3_snprintf(nShmFilename, zShmFilename, 
+                     SQLITE_SHM_DIRECTORY "/sqlite-shm-%x-%x",
+                     (u32)sStat.st_ino, (u32)sStat.st_dev);
+#else
+    sqlite3_snprintf(nShmFilename, zShmFilename, "%s-shm", zBasePath);
+    sqlite3FileSuffix3(pDbFd->zPath, zShmFilename);
+#endif
+    pShmNode->h = -1;
+    pDbFd->pInode->pShmNode = pShmNode;
+    pShmNode->pInode = pDbFd->pInode;
+    if( sqlite3GlobalConfig.bCoreMutex ){
+      pShmNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
+      if( pShmNode->mutex==0 ){
+        rc = SQLITE_NOMEM_BKPT;
+        goto shm_open_err;
+      }
+    }
+
+    if( pInode->bProcessLock==0 ){
+      int openFlags = O_RDWR | O_CREAT;
+      if( sqlite3_uri_boolean(pDbFd->zPath, "readonly_shm", 0) ){
+        openFlags = O_RDONLY;
+        pShmNode->isReadonly = 1;
+      }
+      pShmNode->h = robust_open(zShmFilename, openFlags, (sStat.st_mode&0777));
+      if( pShmNode->h<0 ){
+        rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zShmFilename);
+        goto shm_open_err;
+      }
+
+      /* If this process is running as root, make sure that the SHM file
+      ** is owned by the same user that owns the original database.  Otherwise,
+      ** the original owner will not be able to connect.
+      */
+      robustFchown(pShmNode->h, sStat.st_uid, sStat.st_gid);
+  
+      /* Check to see if another process is holding the dead-man switch.
+      ** If not, truncate the file to zero length. 
+      */
+      rc = SQLITE_OK;
+      if( unixShmSystemLock(pDbFd, F_WRLCK, UNIX_SHM_DMS, 1)==SQLITE_OK ){
+        if( robust_ftruncate(pShmNode->h, 0) ){
+          rc = unixLogError(SQLITE_IOERR_SHMOPEN, "ftruncate", zShmFilename);
+        }
+      }
+      if( rc==SQLITE_OK ){
+        rc = unixShmSystemLock(pDbFd, F_RDLCK, UNIX_SHM_DMS, 1);
+      }
+      if( rc ) goto shm_open_err;
+    }
+  }
+
+  /* Make the new connection a child of the unixShmNode */
+  p->pShmNode = pShmNode;
+#ifdef SQLITE_DEBUG
+  p->id = pShmNode->nextShmId++;
+#endif
+  pShmNode->nRef++;
+  pDbFd->pShm = p;
+  unixLeaveMutex();
+
+  /* The reference count on pShmNode has already been incremented under
+  ** the cover of the unixEnterMutex() mutex and the pointer from the
+  ** new (struct unixShm) object to the pShmNode has been set. All that is
+  ** left to do is to link the new object into the linked list starting
+  ** at pShmNode->pFirst. This must be done while holding the pShmNode->mutex 
+  ** mutex.
+  */
+  sqlite3_mutex_enter(pShmNode->mutex);
+  p->pNext = pShmNode->pFirst;
+  pShmNode->pFirst = p;
+  sqlite3_mutex_leave(pShmNode->mutex);
+  return SQLITE_OK;
+
+  /* Jump here on any error */
+shm_open_err:
+  unixShmPurge(pDbFd);       /* This call frees pShmNode if required */
+  sqlite3_free(p);
+  unixLeaveMutex();
+  return rc;
+}
+
+/*
+** This function is called to obtain a pointer to region iRegion of the 
+** shared-memory associated with the database file fd. Shared-memory regions 
+** are numbered starting from zero. Each shared-memory region is szRegion 
+** bytes in size.
+**
+** If an error occurs, an error code is returned and *pp is set to NULL.
+**
+** Otherwise, if the bExtend parameter is 0 and the requested shared-memory
+** region has not been allocated (by any client, including one running in a
+** separate process), then *pp is set to NULL and SQLITE_OK returned. If 
+** bExtend is non-zero and the requested shared-memory region has not yet 
+** been allocated, it is allocated by this function.
+**
+** If the shared-memory region has already been allocated or is allocated by
+** this call as described above, then it is mapped into this processes 
+** address space (if it is not already), *pp is set to point to the mapped 
+** memory and SQLITE_OK returned.
+*/
+static int unixShmMap(
+  sqlite3_file *fd,               /* Handle open on database file */
+  int iRegion,                    /* Region to retrieve */
+  int szRegion,                   /* Size of regions */
+  int bExtend,                    /* True to extend file if necessary */
+  void volatile **pp              /* OUT: Mapped memory */
+){
+  unixFile *pDbFd = (unixFile*)fd;
+  unixShm *p;
+  unixShmNode *pShmNode;
+  int rc = SQLITE_OK;
+  int nShmPerMap = unixShmRegionPerMap();
+  int nReqRegion;
+
+  /* If the shared-memory file has not yet been opened, open it now. */
+  if( pDbFd->pShm==0 ){
+    rc = unixOpenSharedMemory(pDbFd);
+    if( rc!=SQLITE_OK ) return rc;
+  }
+
+  p = pDbFd->pShm;
+  pShmNode = p->pShmNode;
+  sqlite3_mutex_enter(pShmNode->mutex);
+  assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 );
+  assert( pShmNode->pInode==pDbFd->pInode );
+  assert( pShmNode->h>=0 || pDbFd->pInode->bProcessLock==1 );
+  assert( pShmNode->h<0 || pDbFd->pInode->bProcessLock==0 );
+
+  /* Minimum number of regions required to be mapped. */
+  nReqRegion = ((iRegion+nShmPerMap) / nShmPerMap) * nShmPerMap;
+
+  if( pShmNode->nRegion<nReqRegion ){
+    char **apNew;                      /* New apRegion[] array */
+    int nByte = nReqRegion*szRegion;   /* Minimum required file size */
+    struct stat sStat;                 /* Used by fstat() */
+
+    pShmNode->szRegion = szRegion;
+
+    if( pShmNode->h>=0 ){
+      /* The requested region is not mapped into this processes address space.
+      ** Check to see if it has been allocated (i.e. if the wal-index file is
+      ** large enough to contain the requested region).
+      */
+      if( osFstat(pShmNode->h, &sStat) ){
+        rc = SQLITE_IOERR_SHMSIZE;
+        goto shmpage_out;
+      }
+  
+      if( sStat.st_size<nByte ){
+        /* The requested memory region does not exist. If bExtend is set to
+        ** false, exit early. *pp will be set to NULL and SQLITE_OK returned.
+        */
+        if( !bExtend ){
+          goto shmpage_out;
+        }
+
+        /* Alternatively, if bExtend is true, extend the file. Do this by
+        ** writing a single byte to the end of each (OS) page being
+        ** allocated or extended. Technically, we need only write to the
+        ** last page in order to extend the file. But writing to all new
+        ** pages forces the OS to allocate them immediately, which reduces
+        ** the chances of SIGBUS while accessing the mapped region later on.
+        */
+        else{
+          static const int pgsz = 4096;
+          int iPg;
+
+          /* Write to the last byte of each newly allocated or extended page */
+          assert( (nByte % pgsz)==0 );
+          for(iPg=(sStat.st_size/pgsz); iPg<(nByte/pgsz); iPg++){
+            int x = 0;
+            if( seekAndWriteFd(pShmNode->h, iPg*pgsz + pgsz-1, "", 1, &x)!=1 ){
+              const char *zFile = pShmNode->zFilename;
+              rc = unixLogError(SQLITE_IOERR_SHMSIZE, "write", zFile);
+              goto shmpage_out;
+            }
+          }
+        }
+      }
+    }
+
+    /* Map the requested memory region into this processes address space. */
+    apNew = (char **)sqlite3_realloc(
+        pShmNode->apRegion, nReqRegion*sizeof(char *)
+    );
+    if( !apNew ){
+      rc = SQLITE_IOERR_NOMEM_BKPT;
+      goto shmpage_out;
+    }
+    pShmNode->apRegion = apNew;
+    while( pShmNode->nRegion<nReqRegion ){
+      int nMap = szRegion*nShmPerMap;
+      int i;
+      void *pMem;
+      if( pShmNode->h>=0 ){
+        pMem = osMmap(0, nMap,
+            pShmNode->isReadonly ? PROT_READ : PROT_READ|PROT_WRITE, 
+            MAP_SHARED, pShmNode->h, szRegion*(i64)pShmNode->nRegion
+        );
+        if( pMem==MAP_FAILED ){
+          rc = unixLogError(SQLITE_IOERR_SHMMAP, "mmap", pShmNode->zFilename);
+          goto shmpage_out;
+        }
+      }else{
+        pMem = sqlite3_malloc64(szRegion);
+        if( pMem==0 ){
+          rc = SQLITE_NOMEM_BKPT;
+          goto shmpage_out;
+        }
+        memset(pMem, 0, szRegion);
+      }
+
+      for(i=0; i<nShmPerMap; i++){
+        pShmNode->apRegion[pShmNode->nRegion+i] = &((char*)pMem)[szRegion*i];
+      }
+      pShmNode->nRegion += nShmPerMap;
+    }
+  }
+
+shmpage_out:
+  if( pShmNode->nRegion>iRegion ){
+    *pp = pShmNode->apRegion[iRegion];
+  }else{
+    *pp = 0;
+  }
+  if( pShmNode->isReadonly && rc==SQLITE_OK ) rc = SQLITE_READONLY;
+  sqlite3_mutex_leave(pShmNode->mutex);
+  return rc;
+}
+
+/*
+** Change the lock state for a shared-memory segment.
+**
+** Note that the relationship between SHAREd and EXCLUSIVE locks is a little
+** different here than in posix.  In xShmLock(), one can go from unlocked
+** to shared and back or from unlocked to exclusive and back.  But one may
+** not go from shared to exclusive or from exclusive to shared.
+*/
+static int unixShmLock(
+  sqlite3_file *fd,          /* Database file holding the shared memory */
+  int ofst,                  /* First lock to acquire or release */
+  int n,                     /* Number of locks to acquire or release */
+  int flags                  /* What to do with the lock */
+){
+  unixFile *pDbFd = (unixFile*)fd;      /* Connection holding shared memory */
+  unixShm *p = pDbFd->pShm;             /* The shared memory being locked */
+  unixShm *pX;                          /* For looping over all siblings */
+  unixShmNode *pShmNode = p->pShmNode;  /* The underlying file iNode */
+  int rc = SQLITE_OK;                   /* Result code */
+  u16 mask;                             /* Mask of locks to take or release */
+
+  assert( pShmNode==pDbFd->pInode->pShmNode );
+  assert( pShmNode->pInode==pDbFd->pInode );
+  assert( ofst>=0 && ofst+n<=SQLITE_SHM_NLOCK );
+  assert( n>=1 );
+  assert( flags==(SQLITE_SHM_LOCK | SQLITE_SHM_SHARED)
+       || flags==(SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE)
+       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED)
+       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) );
+  assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 );
+  assert( pShmNode->h>=0 || pDbFd->pInode->bProcessLock==1 );
+  assert( pShmNode->h<0 || pDbFd->pInode->bProcessLock==0 );
+
+  mask = (1<<(ofst+n)) - (1<<ofst);
+  assert( n>1 || mask==(1<<ofst) );
+  sqlite3_mutex_enter(pShmNode->mutex);
+  if( flags & SQLITE_SHM_UNLOCK ){
+    u16 allMask = 0; /* Mask of locks held by siblings */
+
+    /* See if any siblings hold this same lock */
+    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
+      if( pX==p ) continue;
+      assert( (pX->exclMask & (p->exclMask|p->sharedMask))==0 );
+      allMask |= pX->sharedMask;
+    }
+
+    /* Unlock the system-level locks */
+    if( (mask & allMask)==0 ){
+      rc = unixShmSystemLock(pDbFd, F_UNLCK, ofst+UNIX_SHM_BASE, n);
+    }else{
+      rc = SQLITE_OK;
+    }
+
+    /* Undo the local locks */
+    if( rc==SQLITE_OK ){
+      p->exclMask &= ~mask;
+      p->sharedMask &= ~mask;
+    } 
+  }else if( flags & SQLITE_SHM_SHARED ){
+    u16 allShared = 0;  /* Union of locks held by connections other than "p" */
+
+    /* Find out which shared locks are already held by sibling connections.
+    ** If any sibling already holds an exclusive lock, go ahead and return
+    ** SQLITE_BUSY.
+    */
+    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
+      if( (pX->exclMask & mask)!=0 ){
+        rc = SQLITE_BUSY;
+        break;
+      }
+      allShared |= pX->sharedMask;
+    }
+
+    /* Get shared locks at the system level, if necessary */
+    if( rc==SQLITE_OK ){
+      if( (allShared & mask)==0 ){
+        rc = unixShmSystemLock(pDbFd, F_RDLCK, ofst+UNIX_SHM_BASE, n);
+      }else{
+        rc = SQLITE_OK;
+      }
+    }
+
+    /* Get the local shared locks */
+    if( rc==SQLITE_OK ){
+      p->sharedMask |= mask;
+    }
+  }else{
+    /* Make sure no sibling connections hold locks that will block this
+    ** lock.  If any do, return SQLITE_BUSY right away.
+    */
+    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
+      if( (pX->exclMask & mask)!=0 || (pX->sharedMask & mask)!=0 ){
+        rc = SQLITE_BUSY;
+        break;
+      }
+    }
+  
+    /* Get the exclusive locks at the system level.  Then if successful
+    ** also mark the local connection as being locked.
+    */
+    if( rc==SQLITE_OK ){
+      rc = unixShmSystemLock(pDbFd, F_WRLCK, ofst+UNIX_SHM_BASE, n);
+      if( rc==SQLITE_OK ){
+        assert( (p->sharedMask & mask)==0 );
+        p->exclMask |= mask;
+      }
+    }
+  }
+  sqlite3_mutex_leave(pShmNode->mutex);
+  OSTRACE(("SHM-LOCK shmid-%d, pid-%d got %03x,%03x\n",
+           p->id, osGetpid(0), p->sharedMask, p->exclMask));
+  return rc;
+}
+
+/*
+** Implement a memory barrier or memory fence on shared memory.  
+**
+** All loads and stores begun before the barrier must complete before
+** any load or store begun after the barrier.
+*/
+static void unixShmBarrier(
+  sqlite3_file *fd                /* Database file holding the shared memory */
+){
+  UNUSED_PARAMETER(fd);
+  sqlite3MemoryBarrier();         /* compiler-defined memory barrier */
+  unixEnterMutex();               /* Also mutex, for redundancy */
+  unixLeaveMutex();
+}
+
+/*
+** Close a connection to shared-memory.  Delete the underlying 
+** storage if deleteFlag is true.
+**
+** If there is no shared memory associated with the connection then this
+** routine is a harmless no-op.
+*/
+static int unixShmUnmap(
+  sqlite3_file *fd,               /* The underlying database file */
+  int deleteFlag                  /* Delete shared-memory if true */
+){
+  unixShm *p;                     /* The connection to be closed */
+  unixShmNode *pShmNode;          /* The underlying shared-memory file */
+  unixShm **pp;                   /* For looping over sibling connections */
+  unixFile *pDbFd;                /* The underlying database file */
+
+  pDbFd = (unixFile*)fd;
+  p = pDbFd->pShm;
+  if( p==0 ) return SQLITE_OK;
+  pShmNode = p->pShmNode;
+
+  assert( pShmNode==pDbFd->pInode->pShmNode );
+  assert( pShmNode->pInode==pDbFd->pInode );
+
+  /* Remove connection p from the set of connections associated
+  ** with pShmNode */
+  sqlite3_mutex_enter(pShmNode->mutex);
+  for(pp=&pShmNode->pFirst; (*pp)!=p; pp = &(*pp)->pNext){}
+  *pp = p->pNext;
+
+  /* Free the connection p */
+  sqlite3_free(p);
+  pDbFd->pShm = 0;
+  sqlite3_mutex_leave(pShmNode->mutex);
+
+  /* If pShmNode->nRef has reached 0, then close the underlying
+  ** shared-memory file, too */
+  unixEnterMutex();
+  assert( pShmNode->nRef>0 );
+  pShmNode->nRef--;
+  if( pShmNode->nRef==0 ){
+    if( deleteFlag && pShmNode->h>=0 ){
+      osUnlink(pShmNode->zFilename);
+    }
+    unixShmPurge(pDbFd);
+  }
+  unixLeaveMutex();
+
+  return SQLITE_OK;
+}
+
+
+#else
+# define unixShmMap     0
+# define unixShmLock    0
+# define unixShmBarrier 0
+# define unixShmUnmap   0
+#endif /* #ifndef SQLITE_OMIT_WAL */
+
+#if SQLITE_MAX_MMAP_SIZE>0
+/*
+** If it is currently memory mapped, unmap file pFd.
+*/
+static void unixUnmapfile(unixFile *pFd){
+  assert( pFd->nFetchOut==0 );
+  if( pFd->pMapRegion ){
+    osMunmap(pFd->pMapRegion, pFd->mmapSizeActual);
+    pFd->pMapRegion = 0;
+    pFd->mmapSize = 0;
+    pFd->mmapSizeActual = 0;
+  }
+}
+
+/*
+** Attempt to set the size of the memory mapping maintained by file 
+** descriptor pFd to nNew bytes. Any existing mapping is discarded.
+**
+** If successful, this function sets the following variables:
+**
+**       unixFile.pMapRegion
+**       unixFile.mmapSize
+**       unixFile.mmapSizeActual
+**
+** If unsuccessful, an error message is logged via sqlite3_log() and
+** the three variables above are zeroed. In this case SQLite should
+** continue accessing the database using the xRead() and xWrite()
+** methods.
+*/
+static void unixRemapfile(
+  unixFile *pFd,                  /* File descriptor object */
+  i64 nNew                        /* Required mapping size */
+){
+  const char *zErr = "mmap";
+  int h = pFd->h;                      /* File descriptor open on db file */
+  u8 *pOrig = (u8 *)pFd->pMapRegion;   /* Pointer to current file mapping */
+  i64 nOrig = pFd->mmapSizeActual;     /* Size of pOrig region in bytes */
+  u8 *pNew = 0;                        /* Location of new mapping */
+  int flags = PROT_READ;               /* Flags to pass to mmap() */
+
+  assert( pFd->nFetchOut==0 );
+  assert( nNew>pFd->mmapSize );
+  assert( nNew<=pFd->mmapSizeMax );
+  assert( nNew>0 );
+  assert( pFd->mmapSizeActual>=pFd->mmapSize );
+  assert( MAP_FAILED!=0 );
+
+#ifdef SQLITE_MMAP_READWRITE
+  if( (pFd->ctrlFlags & UNIXFILE_RDONLY)==0 ) flags |= PROT_WRITE;
+#endif
+
+  if( pOrig ){
+#if HAVE_MREMAP
+    i64 nReuse = pFd->mmapSize;
+#else
+    const int szSyspage = osGetpagesize();
+    i64 nReuse = (pFd->mmapSize & ~(szSyspage-1));
+#endif
+    u8 *pReq = &pOrig[nReuse];
+
+    /* Unmap any pages of the existing mapping that cannot be reused. */
+    if( nReuse!=nOrig ){
+      osMunmap(pReq, nOrig-nReuse);
+    }
+
+#if HAVE_MREMAP
+    pNew = osMremap(pOrig, nReuse, nNew, MREMAP_MAYMOVE);
+    zErr = "mremap";
+#else
+    pNew = osMmap(pReq, nNew-nReuse, flags, MAP_SHARED, h, nReuse);
+    if( pNew!=MAP_FAILED ){
+      if( pNew!=pReq ){
+        osMunmap(pNew, nNew - nReuse);
+        pNew = 0;
+      }else{
+        pNew = pOrig;
+      }
+    }
+#endif
+
+    /* The attempt to extend the existing mapping failed. Free it. */
+    if( pNew==MAP_FAILED || pNew==0 ){
+      osMunmap(pOrig, nReuse);
+    }
+  }
+
+  /* If pNew is still NULL, try to create an entirely new mapping. */
+  if( pNew==0 ){
+    pNew = osMmap(0, nNew, flags, MAP_SHARED, h, 0);
+  }
+
+  if( pNew==MAP_FAILED ){
+    pNew = 0;
+    nNew = 0;
+    unixLogError(SQLITE_OK, zErr, pFd->zPath);
+
+    /* If the mmap() above failed, assume that all subsequent mmap() calls
+    ** will probably fail too. Fall back to using xRead/xWrite exclusively
+    ** in this case.  */
+    pFd->mmapSizeMax = 0;
+  }
+  pFd->pMapRegion = (void *)pNew;
+  pFd->mmapSize = pFd->mmapSizeActual = nNew;
+}
+
+/*
+** Memory map or remap the file opened by file-descriptor pFd (if the file
+** is already mapped, the existing mapping is replaced by the new). Or, if 
+** there already exists a mapping for this file, and there are still 
+** outstanding xFetch() references to it, this function is a no-op.
+**
+** If parameter nByte is non-negative, then it is the requested size of 
+** the mapping to create. Otherwise, if nByte is less than zero, then the 
+** requested size is the size of the file on disk. The actual size of the
+** created mapping is either the requested size or the value configured 
+** using SQLITE_FCNTL_MMAP_LIMIT, whichever is smaller.
+**
+** SQLITE_OK is returned if no error occurs (even if the mapping is not
+** recreated as a result of outstanding references) or an SQLite error
+** code otherwise.
+*/
+static int unixMapfile(unixFile *pFd, i64 nMap){
+  assert( nMap>=0 || pFd->nFetchOut==0 );
+  assert( nMap>0 || (pFd->mmapSize==0 && pFd->pMapRegion==0) );
+  if( pFd->nFetchOut>0 ) return SQLITE_OK;
+
+  if( nMap<0 ){
+    struct stat statbuf;          /* Low-level file information */
+    if( osFstat(pFd->h, &statbuf) ){
+      return SQLITE_IOERR_FSTAT;
+    }
+    nMap = statbuf.st_size;
+  }
+  if( nMap>pFd->mmapSizeMax ){
+    nMap = pFd->mmapSizeMax;
+  }
+
+  assert( nMap>0 || (pFd->mmapSize==0 && pFd->pMapRegion==0) );
+  if( nMap!=pFd->mmapSize ){
+    unixRemapfile(pFd, nMap);
+  }
+
+  return SQLITE_OK;
+}
+#endif /* SQLITE_MAX_MMAP_SIZE>0 */
+
+/*
+** If possible, return a pointer to a mapping of file fd starting at offset
+** iOff. The mapping must be valid for at least nAmt bytes.
+**
+** If such a pointer can be obtained, store it in *pp and return SQLITE_OK.
+** Or, if one cannot but no error occurs, set *pp to 0 and return SQLITE_OK.
+** Finally, if an error does occur, return an SQLite error code. The final
+** value of *pp is undefined in this case.
+**
+** If this function does return a pointer, the caller must eventually 
+** release the reference by calling unixUnfetch().
+*/
+static int unixFetch(sqlite3_file *fd, i64 iOff, int nAmt, void **pp){
+#if SQLITE_MAX_MMAP_SIZE>0
+  unixFile *pFd = (unixFile *)fd;   /* The underlying database file */
+#endif
+  *pp = 0;
+
+#if SQLITE_MAX_MMAP_SIZE>0
+  if( pFd->mmapSizeMax>0 ){
+    if( pFd->pMapRegion==0 ){
+      int rc = unixMapfile(pFd, -1);
+      if( rc!=SQLITE_OK ) return rc;
+    }
+    if( pFd->mmapSize >= iOff+nAmt ){
+      *pp = &((u8 *)pFd->pMapRegion)[iOff];
+      pFd->nFetchOut++;
+    }
+  }
+#endif
+  return SQLITE_OK;
+}
+
+/*
+** If the third argument is non-NULL, then this function releases a 
+** reference obtained by an earlier call to unixFetch(). The second
+** argument passed to this function must be the same as the corresponding
+** argument that was passed to the unixFetch() invocation. 
+**
+** Or, if the third argument is NULL, then this function is being called 
+** to inform the VFS layer that, according to POSIX, any existing mapping 
+** may now be invalid and should be unmapped.
+*/
+static int unixUnfetch(sqlite3_file *fd, i64 iOff, void *p){
+#if SQLITE_MAX_MMAP_SIZE>0
+  unixFile *pFd = (unixFile *)fd;   /* The underlying database file */
+  UNUSED_PARAMETER(iOff);
+
+  /* If p==0 (unmap the entire file) then there must be no outstanding 
+  ** xFetch references. Or, if p!=0 (meaning it is an xFetch reference),
+  ** then there must be at least one outstanding.  */
+  assert( (p==0)==(pFd->nFetchOut==0) );
+
+  /* If p!=0, it must match the iOff value. */
+  assert( p==0 || p==&((u8 *)pFd->pMapRegion)[iOff] );
+
+  if( p ){
+    pFd->nFetchOut--;
+  }else{
+    unixUnmapfile(pFd);
+  }
+
+  assert( pFd->nFetchOut>=0 );
+#else
+  UNUSED_PARAMETER(fd);
+  UNUSED_PARAMETER(p);
+  UNUSED_PARAMETER(iOff);
+#endif
+  return SQLITE_OK;
+}
+
+/*
+** Here ends the implementation of all sqlite3_file methods.
+**
+********************** End sqlite3_file Methods *******************************
+******************************************************************************/
+
+/*
+** This division contains definitions of sqlite3_io_methods objects that
+** implement various file locking strategies.  It also contains definitions
+** of "finder" functions.  A finder-function is used to locate the appropriate
+** sqlite3_io_methods object for a particular database file.  The pAppData
+** field of the sqlite3_vfs VFS objects are initialized to be pointers to
+** the correct finder-function for that VFS.
+**
+** Most finder functions return a pointer to a fixed sqlite3_io_methods
+** object.  The only interesting finder-function is autolockIoFinder, which
+** looks at the filesystem type and tries to guess the best locking
+** strategy from that.
+**
+** For finder-function F, two objects are created:
+**
+**    (1) The real finder-function named "FImpt()".
+**
+**    (2) A constant pointer to this function named just "F".
+**
+**
+** A pointer to the F pointer is used as the pAppData value for VFS
+** objects.  We have to do this instead of letting pAppData point
+** directly at the finder-function since C90 rules prevent a void*
+** from be cast into a function pointer.
+**
+**
+** Each instance of this macro generates two objects:
+**
+**   *  A constant sqlite3_io_methods object call METHOD that has locking
+**      methods CLOSE, LOCK, UNLOCK, CKRESLOCK.
+**
+**   *  An I/O method finder function called FINDER that returns a pointer
+**      to the METHOD object in the previous bullet.
+*/
+#define IOMETHODS(FINDER,METHOD,VERSION,CLOSE,LOCK,UNLOCK,CKLOCK,SHMMAP)     \
+static const sqlite3_io_methods METHOD = {                                   \
+   VERSION,                    /* iVersion */                                \
+   CLOSE,                      /* xClose */                                  \
+   unixRead,                   /* xRead */                                   \
+   unixWrite,                  /* xWrite */                                  \
+   unixTruncate,               /* xTruncate */                               \
+   unixSync,                   /* xSync */                                   \
+   unixFileSize,               /* xFileSize */                               \
+   LOCK,                       /* xLock */                                   \
+   UNLOCK,                     /* xUnlock */                                 \
+   CKLOCK,                     /* xCheckReservedLock */                      \
+   unixFileControl,            /* xFileControl */                            \
+   unixSectorSize,             /* xSectorSize */                             \
+   unixDeviceCharacteristics,  /* xDeviceCapabilities */                     \
+   SHMMAP,                     /* xShmMap */                                 \
+   unixShmLock,                /* xShmLock */                                \
+   unixShmBarrier,             /* xShmBarrier */                             \
+   unixShmUnmap,               /* xShmUnmap */                               \
+   unixFetch,                  /* xFetch */                                  \
+   unixUnfetch,                /* xUnfetch */                                \
+};                                                                           \
+static const sqlite3_io_methods *FINDER##Impl(const char *z, unixFile *p){   \
+  UNUSED_PARAMETER(z); UNUSED_PARAMETER(p);                                  \
+  return &METHOD;                                                            \
+}                                                                            \
+static const sqlite3_io_methods *(*const FINDER)(const char*,unixFile *p)    \
+    = FINDER##Impl;
+
+/*
+** Here are all of the sqlite3_io_methods objects for each of the
+** locking strategies.  Functions that return pointers to these methods
+** are also created.
+*/
+IOMETHODS(
+  posixIoFinder,            /* Finder function name */
+  posixIoMethods,           /* sqlite3_io_methods object name */
+  3,                        /* shared memory and mmap are enabled */
+  unixClose,                /* xClose method */
+  unixLock,                 /* xLock method */
+  unixUnlock,               /* xUnlock method */
+  unixCheckReservedLock,    /* xCheckReservedLock method */
+  unixShmMap                /* xShmMap method */
+)
+IOMETHODS(
+  nolockIoFinder,           /* Finder function name */
+  nolockIoMethods,          /* sqlite3_io_methods object name */
+  3,                        /* shared memory is disabled */
+  nolockClose,              /* xClose method */
+  nolockLock,               /* xLock method */
+  nolockUnlock,             /* xUnlock method */
+  nolockCheckReservedLock,  /* xCheckReservedLock method */
+  0                         /* xShmMap method */
+)
+IOMETHODS(
+  dotlockIoFinder,          /* Finder function name */
+  dotlockIoMethods,         /* sqlite3_io_methods object name */
+  1,                        /* shared memory is disabled */
+  dotlockClose,             /* xClose method */
+  dotlockLock,              /* xLock method */
+  dotlockUnlock,            /* xUnlock method */
+  dotlockCheckReservedLock, /* xCheckReservedLock method */
+  0                         /* xShmMap method */
+)
+
+#if SQLITE_ENABLE_LOCKING_STYLE
+IOMETHODS(
+  flockIoFinder,            /* Finder function name */
+  flockIoMethods,           /* sqlite3_io_methods object name */
+  1,                        /* shared memory is disabled */
+  flockClose,               /* xClose method */
+  flockLock,                /* xLock method */
+  flockUnlock,              /* xUnlock method */
+  flockCheckReservedLock,   /* xCheckReservedLock method */
+  0                         /* xShmMap method */
+)
+#endif
+
+#if OS_VXWORKS
+IOMETHODS(
+  semIoFinder,              /* Finder function name */
+  semIoMethods,             /* sqlite3_io_methods object name */
+  1,                        /* shared memory is disabled */
+  semXClose,                /* xClose method */
+  semXLock,                 /* xLock method */
+  semXUnlock,               /* xUnlock method */
+  semXCheckReservedLock,    /* xCheckReservedLock method */
+  0                         /* xShmMap method */
+)
+#endif
+
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+IOMETHODS(
+  afpIoFinder,              /* Finder function name */
+  afpIoMethods,             /* sqlite3_io_methods object name */
+  1,                        /* shared memory is disabled */
+  afpClose,                 /* xClose method */
+  afpLock,                  /* xLock method */
+  afpUnlock,                /* xUnlock method */
+  afpCheckReservedLock,     /* xCheckReservedLock method */
+  0                         /* xShmMap method */
+)
+#endif
+
+/*
+** The proxy locking method is a "super-method" in the sense that it
+** opens secondary file descriptors for the conch and lock files and
+** it uses proxy, dot-file, AFP, and flock() locking methods on those
+** secondary files.  For this reason, the division that implements
+** proxy locking is located much further down in the file.  But we need
+** to go ahead and define the sqlite3_io_methods and finder function
+** for proxy locking here.  So we forward declare the I/O methods.
+*/
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+static int proxyClose(sqlite3_file*);
+static int proxyLock(sqlite3_file*, int);
+static int proxyUnlock(sqlite3_file*, int);
+static int proxyCheckReservedLock(sqlite3_file*, int*);
+IOMETHODS(
+  proxyIoFinder,            /* Finder function name */
+  proxyIoMethods,           /* sqlite3_io_methods object name */
+  1,                        /* shared memory is disabled */
+  proxyClose,               /* xClose method */
+  proxyLock,                /* xLock method */
+  proxyUnlock,              /* xUnlock method */
+  proxyCheckReservedLock,   /* xCheckReservedLock method */
+  0                         /* xShmMap method */
+)
+#endif
+
+/* nfs lockd on OSX 10.3+ doesn't clear write locks when a read lock is set */
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+IOMETHODS(
+  nfsIoFinder,               /* Finder function name */
+  nfsIoMethods,              /* sqlite3_io_methods object name */
+  1,                         /* shared memory is disabled */
+  unixClose,                 /* xClose method */
+  unixLock,                  /* xLock method */
+  nfsUnlock,                 /* xUnlock method */
+  unixCheckReservedLock,     /* xCheckReservedLock method */
+  0                          /* xShmMap method */
+)
+#endif
+
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+/* 
+** This "finder" function attempts to determine the best locking strategy 
+** for the database file "filePath".  It then returns the sqlite3_io_methods
+** object that implements that strategy.
+**
+** This is for MacOSX only.
+*/
+static const sqlite3_io_methods *autolockIoFinderImpl(
+  const char *filePath,    /* name of the database file */
+  unixFile *pNew           /* open file object for the database file */
+){
+  static const struct Mapping {
+    const char *zFilesystem;              /* Filesystem type name */
+    const sqlite3_io_methods *pMethods;   /* Appropriate locking method */
+  } aMap[] = {
+    { "hfs",    &posixIoMethods },
+    { "ufs",    &posixIoMethods },
+    { "afpfs",  &afpIoMethods },
+    { "smbfs",  &afpIoMethods },
+    { "webdav", &nolockIoMethods },
+    { 0, 0 }
+  };
+  int i;
+  struct statfs fsInfo;
+  struct flock lockInfo;
+
+  if( !filePath ){
+    /* If filePath==NULL that means we are dealing with a transient file
+    ** that does not need to be locked. */
+    return &nolockIoMethods;
+  }
+  if( statfs(filePath, &fsInfo) != -1 ){
+    if( fsInfo.f_flags & MNT_RDONLY ){
+      return &nolockIoMethods;
+    }
+    for(i=0; aMap[i].zFilesystem; i++){
+      if( strcmp(fsInfo.f_fstypename, aMap[i].zFilesystem)==0 ){
+        return aMap[i].pMethods;
+      }
+    }
+  }
+
+  /* Default case. Handles, amongst others, "nfs".
+  ** Test byte-range lock using fcntl(). If the call succeeds, 
+  ** assume that the file-system supports POSIX style locks. 
+  */
+  lockInfo.l_len = 1;
+  lockInfo.l_start = 0;
+  lockInfo.l_whence = SEEK_SET;
+  lockInfo.l_type = F_RDLCK;
+  if( osFcntl(pNew->h, F_GETLK, &lockInfo)!=-1 ) {
+    if( strcmp(fsInfo.f_fstypename, "nfs")==0 ){
+      return &nfsIoMethods;
+    } else {
+      return &posixIoMethods;
+    }
+  }else{
+    return &dotlockIoMethods;
+  }
+}
+static const sqlite3_io_methods 
+  *(*const autolockIoFinder)(const char*,unixFile*) = autolockIoFinderImpl;
+
+#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
+
+#if OS_VXWORKS
+/*
+** This "finder" function for VxWorks checks to see if posix advisory
+** locking works.  If it does, then that is what is used.  If it does not
+** work, then fallback to named semaphore locking.
+*/
+static const sqlite3_io_methods *vxworksIoFinderImpl(
+  const char *filePath,    /* name of the database file */
+  unixFile *pNew           /* the open file object */
+){
+  struct flock lockInfo;
+
+  if( !filePath ){
+    /* If filePath==NULL that means we are dealing with a transient file
+    ** that does not need to be locked. */
+    return &nolockIoMethods;
+  }
+
+  /* Test if fcntl() is supported and use POSIX style locks.
+  ** Otherwise fall back to the named semaphore method.
+  */
+  lockInfo.l_len = 1;
+  lockInfo.l_start = 0;
+  lockInfo.l_whence = SEEK_SET;
+  lockInfo.l_type = F_RDLCK;
+  if( osFcntl(pNew->h, F_GETLK, &lockInfo)!=-1 ) {
+    return &posixIoMethods;
+  }else{
+    return &semIoMethods;
+  }
+}
+static const sqlite3_io_methods 
+  *(*const vxworksIoFinder)(const char*,unixFile*) = vxworksIoFinderImpl;
+
+#endif /* OS_VXWORKS */
+
+/*
+** An abstract type for a pointer to an IO method finder function:
+*/
+typedef const sqlite3_io_methods *(*finder_type)(const char*,unixFile*);
+
+
+/****************************************************************************
+**************************** sqlite3_vfs methods ****************************
+**
+** This division contains the implementation of methods on the
+** sqlite3_vfs object.
+*/
+
+/*
+** Initialize the contents of the unixFile structure pointed to by pId.
+*/
+static int fillInUnixFile(
+  sqlite3_vfs *pVfs,      /* Pointer to vfs object */
+  int h,                  /* Open file descriptor of file being opened */
+  sqlite3_file *pId,      /* Write to the unixFile structure here */
+  const char *zFilename,  /* Name of the file being opened */
+  int ctrlFlags           /* Zero or more UNIXFILE_* values */
+){
+  const sqlite3_io_methods *pLockingStyle;
+  unixFile *pNew = (unixFile *)pId;
+  int rc = SQLITE_OK;
+
+  assert( pNew->pInode==NULL );
+
+  /* Usually the path zFilename should not be a relative pathname. The
+  ** exception is when opening the proxy "conch" file in builds that
+  ** include the special Apple locking styles.
+  */
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+  assert( zFilename==0 || zFilename[0]=='/' 
+    || pVfs->pAppData==(void*)&autolockIoFinder );
+#else
+  assert( zFilename==0 || zFilename[0]=='/' );
+#endif
+
+  /* No locking occurs in temporary files */
+  assert( zFilename!=0 || (ctrlFlags & UNIXFILE_NOLOCK)!=0 );
+
+  OSTRACE(("OPEN    %-3d %s\n", h, zFilename));
+  pNew->h = h;
+  pNew->pVfs = pVfs;
+  pNew->zPath = zFilename;
+  pNew->ctrlFlags = (u8)ctrlFlags;
+#if SQLITE_MAX_MMAP_SIZE>0
+  pNew->mmapSizeMax = sqlite3GlobalConfig.szMmap;
+#endif
+  if( sqlite3_uri_boolean(((ctrlFlags & UNIXFILE_URI) ? zFilename : 0),
+                           "psow", SQLITE_POWERSAFE_OVERWRITE) ){
+    pNew->ctrlFlags |= UNIXFILE_PSOW;
+  }
+  if( strcmp(pVfs->zName,"unix-excl")==0 ){
+    pNew->ctrlFlags |= UNIXFILE_EXCL;
+  }
+
+#if OS_VXWORKS
+  pNew->pId = vxworksFindFileId(zFilename);
+  if( pNew->pId==0 ){
+    ctrlFlags |= UNIXFILE_NOLOCK;
+    rc = SQLITE_NOMEM_BKPT;
+  }
+#endif
+
+  if( ctrlFlags & UNIXFILE_NOLOCK ){
+    pLockingStyle = &nolockIoMethods;
+  }else{
+    pLockingStyle = (**(finder_type*)pVfs->pAppData)(zFilename, pNew);
+#if SQLITE_ENABLE_LOCKING_STYLE
+    /* Cache zFilename in the locking context (AFP and dotlock override) for
+    ** proxyLock activation is possible (remote proxy is based on db name)
+    ** zFilename remains valid until file is closed, to support */
+    pNew->lockingContext = (void*)zFilename;
+#endif
+  }
+
+  if( pLockingStyle == &posixIoMethods
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+    || pLockingStyle == &nfsIoMethods
+#endif
+  ){
+    unixEnterMutex();
+    rc = findInodeInfo(pNew, &pNew->pInode);
+    if( rc!=SQLITE_OK ){
+      /* If an error occurred in findInodeInfo(), close the file descriptor
+      ** immediately, before releasing the mutex. findInodeInfo() may fail
+      ** in two scenarios:
+      **
+      **   (a) A call to fstat() failed.
+      **   (b) A malloc failed.
+      **
+      ** Scenario (b) may only occur if the process is holding no other
+      ** file descriptors open on the same file. If there were other file
+      ** descriptors on this file, then no malloc would be required by
+      ** findInodeInfo(). If this is the case, it is quite safe to close
+      ** handle h - as it is guaranteed that no posix locks will be released
+      ** by doing so.
+      **
+      ** If scenario (a) caused the error then things are not so safe. The
+      ** implicit assumption here is that if fstat() fails, things are in
+      ** such bad shape that dropping a lock or two doesn't matter much.
+      */
+      robust_close(pNew, h, __LINE__);
+      h = -1;
+    }
+    unixLeaveMutex();
+  }
+
+#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
+  else if( pLockingStyle == &afpIoMethods ){
+    /* AFP locking uses the file path so it needs to be included in
+    ** the afpLockingContext.
+    */
+    afpLockingContext *pCtx;
+    pNew->lockingContext = pCtx = sqlite3_malloc64( sizeof(*pCtx) );
+    if( pCtx==0 ){
+      rc = SQLITE_NOMEM_BKPT;
+    }else{
+      /* NB: zFilename exists and remains valid until the file is closed
+      ** according to requirement F11141.  So we do not need to make a
+      ** copy of the filename. */
+      pCtx->dbPath = zFilename;
+      pCtx->reserved = 0;
+      srandomdev();
+      unixEnterMutex();
+      rc = findInodeInfo(pNew, &pNew->pInode);
+      if( rc!=SQLITE_OK ){
+        sqlite3_free(pNew->lockingContext);
+        robust_close(pNew, h, __LINE__);
+        h = -1;
+      }
+      unixLeaveMutex();        
+    }
+  }
+#endif
+
+  else if( pLockingStyle == &dotlockIoMethods ){
+    /* Dotfile locking uses the file path so it needs to be included in
+    ** the dotlockLockingContext 
+    */
+    char *zLockFile;
+    int nFilename;
+    assert( zFilename!=0 );
+    nFilename = (int)strlen(zFilename) + 6;
+    zLockFile = (char *)sqlite3_malloc64(nFilename);
+    if( zLockFile==0 ){
+      rc = SQLITE_NOMEM_BKPT;
+    }else{
+      sqlite3_snprintf(nFilename, zLockFile, "%s" DOTLOCK_SUFFIX, zFilename);
+    }
+    pNew->lockingContext = zLockFile;
+  }
+
+#if OS_VXWORKS
+  else if( pLockingStyle == &semIoMethods ){
+    /* Named semaphore locking uses the file path so it needs to be
+    ** included in the semLockingContext
+    */
+    unixEnterMutex();
+    rc = findInodeInfo(pNew, &pNew->pInode);
+    if( (rc==SQLITE_OK) && (pNew->pInode->pSem==NULL) ){
+      char *zSemName = pNew->pInode->aSemName;
+      int n;
+      sqlite3_snprintf(MAX_PATHNAME, zSemName, "/%s.sem",
+                       pNew->pId->zCanonicalName);
+      for( n=1; zSemName[n]; n++ )
+        if( zSemName[n]=='/' ) zSemName[n] = '_';
+      pNew->pInode->pSem = sem_open(zSemName, O_CREAT, 0666, 1);
+      if( pNew->pInode->pSem == SEM_FAILED ){
+        rc = SQLITE_NOMEM_BKPT;
+        pNew->pInode->aSemName[0] = '\0';
+      }
+    }
+    unixLeaveMutex();
+  }
+#endif
+  
+  storeLastErrno(pNew, 0);
+#if OS_VXWORKS
+  if( rc!=SQLITE_OK ){
+    if( h>=0 ) robust_close(pNew, h, __LINE__);
+    h = -1;
+    osUnlink(zFilename);
+    pNew->ctrlFlags |= UNIXFILE_DELETE;
+  }
+#endif
+  if( rc!=SQLITE_OK ){
+    if( h>=0 ) robust_close(pNew, h, __LINE__);
+  }else{
+    pNew->pMethod = pLockingStyle;
+    OpenCounter(+1);
+    verifyDbFile(pNew);
+  }
+  return rc;
+}
+
+/*
+** Return the name of a directory in which to put temporary files.
+** If no suitable temporary file directory can be found, return NULL.
+*/
+static const char *unixTempFileDir(void){
+  static const char *azDirs[] = {
+     0,
+     0,
+     "/var/tmp",
+     "/usr/tmp",
+     "/tmp",
+     "."
+  };
+  unsigned int i = 0;
+  struct stat buf;
+  const char *zDir = sqlite3_temp_directory;
+
+  if( !azDirs[0] ) azDirs[0] = getenv("SQLITE_TMPDIR");
+  if( !azDirs[1] ) azDirs[1] = getenv("TMPDIR");
+  while(1){
+    if( zDir!=0
+     && osStat(zDir, &buf)==0
+     && S_ISDIR(buf.st_mode)
+     && osAccess(zDir, 03)==0
+    ){
+      return zDir;
+    }
+    if( i>=sizeof(azDirs)/sizeof(azDirs[0]) ) break;
+    zDir = azDirs[i++];
+  }
+  return 0;
+}
+
+/*
+** Create a temporary file name in zBuf.  zBuf must be allocated
+** by the calling process and must be big enough to hold at least
+** pVfs->mxPathname bytes.
+*/
+static int unixGetTempname(int nBuf, char *zBuf){
+  const char *zDir;
+  int iLimit = 0;
+
+  /* It's odd to simulate an io-error here, but really this is just
+  ** using the io-error infrastructure to test that SQLite handles this
+  ** function failing. 
+  */
+  zBuf[0] = 0;
+  SimulateIOError( return SQLITE_IOERR );
+
+  zDir = unixTempFileDir();
+  if( zDir==0 ) return SQLITE_IOERR_GETTEMPPATH;
+  do{
+    u64 r;
+    sqlite3_randomness(sizeof(r), &r);
+    assert( nBuf>2 );
+    zBuf[nBuf-2] = 0;
+    sqlite3_snprintf(nBuf, zBuf, "%s/"SQLITE_TEMP_FILE_PREFIX"%llx%c",
+                     zDir, r, 0);
+    if( zBuf[nBuf-2]!=0 || (iLimit++)>10 ) return SQLITE_ERROR;
+  }while( osAccess(zBuf,0)==0 );
+  return SQLITE_OK;
+}
+
+#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
+/*
+** Routine to transform a unixFile into a proxy-locking unixFile.
+** Implementation in the proxy-lock division, but used by unixOpen()
+** if SQLITE_PREFER_PROXY_LOCKING is defined.
+*/
+static int proxyTransformUnixFile(unixFile*, const char*);
+#endif
+
+/*
+** Search for an unused file descriptor that was opened on the database 
+** file (not a journal or master-journal file) identified by pathname
+** zPath with SQLITE_OPEN_XXX flags matching those passed as the second
+** argument to this function.
+**
+** Such a file descriptor may exist if a database connection was closed
+** but the associated file descriptor could not be closed because some
+** other file descriptor open on the same file is holding a file-lock.
+** Refer to comments in the unixClose() function and the lengthy comment
+** describing "Posix Advisory Locking" at the start of this file for 
+** further details. Also, ticket #4018.
+**
+** If a suitable file descriptor is found, then it is returned. If no
+** such file descriptor is located, -1 is returned.
+*/
+static UnixUnusedFd *findReusableFd(const char *zPath, int flags){
+  UnixUnusedFd *pUnused = 0;
+
+  /* Do not search for an unused file descriptor on vxworks. Not because
+  ** vxworks would not benefit from the change (it might, we're not sure),
+  ** but because no way to test it is currently available. It is better 
+  ** not to risk breaking vxworks support for the sake of such an obscure 
+  ** feature.  */
+#if !OS_VXWORKS
+  struct stat sStat;                   /* Results of stat() call */
+
+  /* A stat() call may fail for various reasons. If this happens, it is
+  ** almost certain that an open() call on the same path will also fail.
+  ** For this reason, if an error occurs in the stat() call here, it is
+  ** ignored and -1 is returned. The caller will try to open a new file
+  ** descriptor on the same path, fail, and return an error to SQLite.
+  **
+  ** Even if a subsequent open() call does succeed, the consequences of
+  ** not searching for a reusable file descriptor are not dire.  */
+  if( 0==osStat(zPath, &sStat) ){
+    unixInodeInfo *pInode;
+
+    unixEnterMutex();
+    pInode = inodeList;
+    while( pInode && (pInode->fileId.dev!=sStat.st_dev
+                     || pInode->fileId.ino!=sStat.st_ino) ){
+       pInode = pInode->pNext;
+    }
+    if( pInode ){
+      UnixUnusedFd **pp;
+      for(pp=&pInode->pUnused; *pp && (*pp)->flags!=flags; pp=&((*pp)->pNext));
+      pUnused = *pp;
+      if( pUnused ){
+        *pp = pUnused->pNext;
+      }
+    }
+    unixLeaveMutex();
+  }
+#endif    /* if !OS_VXWORKS */
+  return pUnused;
+}
+
+/*
+** Find the mode, uid and gid of file zFile. 
+*/
+static int getFileMode(
+  const char *zFile,              /* File name */
+  mode_t *pMode,                  /* OUT: Permissions of zFile */
+  uid_t *pUid,                    /* OUT: uid of zFile. */
+  gid_t *pGid                     /* OUT: gid of zFile. */
+){
+  struct stat sStat;              /* Output of stat() on database file */
+  int rc = SQLITE_OK;
+  if( 0==osStat(zFile, &sStat) ){
+    *pMode = sStat.st_mode & 0777;
+    *pUid = sStat.st_uid;
+    *pGid = sStat.st_gid;
+  }else{
+    rc = SQLITE_IOERR_FSTAT;
+  }
+  return rc;
+}
+
+/*
+** This function is called by unixOpen() to determine the unix permissions
+** to create new files with. If no error occurs, then SQLITE_OK is returned
+** and a value suitable for passing as the third argument to open(2) is
+** written to *pMode. If an IO error occurs, an SQLite error code is 
+** returned and the value of *pMode is not modified.
+**
+** In most cases, this routine sets *pMode to 0, which will become
+** an indication to robust_open() to create the file using
+** SQLITE_DEFAULT_FILE_PERMISSIONS adjusted by the umask.
+** But if the file being opened is a WAL or regular journal file, then 
+** this function queries the file-system for the permissions on the 
+** corresponding database file and sets *pMode to this value. Whenever 
+** possible, WAL and journal files are created using the same permissions 
+** as the associated database file.
+**
+** If the SQLITE_ENABLE_8_3_NAMES option is enabled, then the
+** original filename is unavailable.  But 8_3_NAMES is only used for
+** FAT filesystems and permissions do not matter there, so just use
+** the default permissions.
+*/
+static int findCreateFileMode(
+  const char *zPath,              /* Path of file (possibly) being created */
+  int flags,                      /* Flags passed as 4th argument to xOpen() */
+  mode_t *pMode,                  /* OUT: Permissions to open file with */
+  uid_t *pUid,                    /* OUT: uid to set on the file */
+  gid_t *pGid                     /* OUT: gid to set on the file */
+){
+  int rc = SQLITE_OK;             /* Return Code */
+  *pMode = 0;
+  *pUid = 0;
+  *pGid = 0;
+  if( flags & (SQLITE_OPEN_WAL|SQLITE_OPEN_MAIN_JOURNAL) ){
+    char zDb[MAX_PATHNAME+1];     /* Database file path */
+    int nDb;                      /* Number of valid bytes in zDb */
+
+    /* zPath is a path to a WAL or journal file. The following block derives
+    ** the path to the associated database file from zPath. This block handles
+    ** the following naming conventions:
+    **
+    **   "<path to db>-journal"
+    **   "<path to db>-wal"
+    **   "<path to db>-journalNN"
+    **   "<path to db>-walNN"
+    **
+    ** where NN is a decimal number. The NN naming schemes are 
+    ** used by the test_multiplex.c module.
+    */
+    nDb = sqlite3Strlen30(zPath) - 1; 
+    while( zPath[nDb]!='-' ){
+#ifndef SQLITE_ENABLE_8_3_NAMES
+      /* In the normal case (8+3 filenames disabled) the journal filename
+      ** is guaranteed to contain a '-' character. */
+      assert( nDb>0 );
+      assert( sqlite3Isalnum(zPath[nDb]) );
+#else
+      /* If 8+3 names are possible, then the journal file might not contain
+      ** a '-' character.  So check for that case and return early. */
+      if( nDb==0 || zPath[nDb]=='.' ) return SQLITE_OK;
+#endif
+      nDb--;
+    }
+    memcpy(zDb, zPath, nDb);
+    zDb[nDb] = '\0';
+
+    rc = getFileMode(zDb, pMode, pUid, pGid);
+  }else if( flags & SQLITE_OPEN_DELETEONCLOSE ){
+    *pMode = 0600;
+  }else if( flags & SQLITE_OPEN_URI ){
+    /* If this is a main database file and the file was opened using a URI
+    ** filename, check for the "modeof" parameter. If present, interpret
+    ** its value as a filename and try to copy the mode, uid and gid from
+    ** that file.  */
+    const char *z = sqlite3_uri_parameter(zPath, "modeof");
+    if( z ){
+      rc = getFileMode(z, pMode, pUid, pGid);
+    }
+  }
+  return rc;
+}
+
+/*
+** Open the file zPath.
+** 
+** Previously, the SQLite OS layer used three functions in place of this
+** one:
+**
+**     sqlite3OsOpenReadWrite();
+**     sqlite3OsOpenReadOnly();
+**     sqlite3OsOpenExclusive();
+**
+** These calls correspond to the following combinations of flags:
+**
+**     ReadWrite() ->     (READWRITE | CREATE)
+**     ReadOnly()  ->     (READONLY) 
+**     OpenExclusive() -> (READWRITE | CREATE | EXCLUSIVE)
+**
+** The old OpenExclusive() accepted a boolean argument - "delFlag". If
+** true, the file was configured to be automatically deleted when the
+** file handle closed. To achieve the same effect using this new 
+** interface, add the DELETEONCLOSE flag to those specified above for 
+** OpenExclusive().
+*/
+static int unixOpen(
+  sqlite3_vfs *pVfs,           /* The VFS for which this is the xOpen method */
+  const char *zPath,           /* Pathname of file to be opened */
+  sqlite3_file *pFile,         /* The file descriptor to be filled in */
+  int flags,                   /* Input flags to control the opening */
+  int *pOutFlags               /* Output flags returned to SQLite core */
+){
+  unixFile *p = (unixFile *)pFile;
+  int fd = -1;                   /* File descriptor returned by open() */
+  int openFlags = 0;             /* Flags to pass to open() */
+  int eType = flags&0xFFFFFF00;  /* Type of file to open */
+  int noLock;                    /* True to omit locking primitives */
+  int rc = SQLITE_OK;            /* Function Return Code */
+  int ctrlFlags = 0;             /* UNIXFILE_* flags */
+
+  int isExclusive  = (flags & SQLITE_OPEN_EXCLUSIVE);
+  int isDelete     = (flags & SQLITE_OPEN_DELETEONCLOSE);
+  int isCreate     = (flags & SQLITE_OPEN_CREATE);
+  int isReadonly   = (flags & SQLITE_OPEN_READONLY);
+  int isReadWrite  = (flags & SQLITE_OPEN_READWRITE);
+#if SQLITE_ENABLE_LOCKING_STYLE
+  int isAutoProxy  = (flags & SQLITE_OPEN_AUTOPROXY);
+#endif
+#if defined(__APPLE__) || SQLITE_ENABLE_LOCKING_STYLE
+  struct statfs fsInfo;
+#endif
+
+  /* If creating a master or main-file journal, this function will open
+  ** a file-descriptor on the directory too. The first time unixSync()
+  ** is called the directory file descriptor will be fsync()ed and close()d.
+  */
+  int syncDir = (isCreate && (
+        eType==SQLITE_OPEN_MASTER_JOURNAL 
+     || eType==SQLITE_OPEN_MAIN_JOURNAL 
+     || eType==SQLITE_OPEN_WAL
+  ));
+
+  /* If argument zPath is a NULL pointer, this function is required to open
+  ** a temporary file. Use this buffer to store the file name in.
+  */
+  char zTmpname[MAX_PATHNAME+2];
+  const char *zName = zPath;
+
+  /* Check the following statements are true: 
+  **
+  **   (a) Exactly one of the READWRITE and READONLY flags must be set, and 
+  **   (b) if CREATE is set, then READWRITE must also be set, and
+  **   (c) if EXCLUSIVE is set, then CREATE must also be set.
+  **   (d) if DELETEONCLOSE is set, then CREATE must also be set.
+  */
+  assert((isReadonly==0 || isReadWrite==0) && (isReadWrite || isReadonly));
+  assert(isCreate==0 || isReadWrite);
+  assert(isExclusive==0 || isCreate);
+  assert(isDelete==0 || isCreate);
+
+  /* The main DB, main journal, WAL file and master journal are never 
+  ** automatically deleted. Nor are they ever temporary files.  */
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_DB );
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_JOURNAL );
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MASTER_JOURNAL );
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_WAL );
+
+  /* Assert that the upper layer has set one of the "file-type" flags. */
+  assert( eType==SQLITE_OPEN_MAIN_DB      || eType==SQLITE_OPEN_TEMP_DB 
+       || eType==SQLITE_OPEN_MAIN_JOURNAL || eType==SQLITE_OPEN_TEMP_JOURNAL 
+       || eType==SQLITE_OPEN_SUBJOURNAL   || eType==SQLITE_OPEN_MASTER_JOURNAL 
+       || eType==SQLITE_OPEN_TRANSIENT_DB || eType==SQLITE_OPEN_WAL
+  );
+
+  /* Detect a pid change and reset the PRNG.  There is a race condition
+  ** here such that two or more threads all trying to open databases at
+  ** the same instant might all reset the PRNG.  But multiple resets
+  ** are harmless.
+  */
+  if( randomnessPid!=osGetpid(0) ){
+    randomnessPid = osGetpid(0);
+    sqlite3_randomness(0,0);
+  }
+
+  memset(p, 0, sizeof(unixFile));
+
+  if( eType==SQLITE_OPEN_MAIN_DB ){
+    UnixUnusedFd *pUnused;
+    pUnused = findReusableFd(zName, flags);
+    if( pUnused ){
+      fd = pUnused->fd;
+    }else{
+      pUnused = sqlite3_malloc64(sizeof(*pUnused));
+      if( !pUnused ){
+        return SQLITE_NOMEM_BKPT;
+      }
+    }
+    p->pUnused = pUnused;
+
+    /* Database filenames are double-zero terminated if they are not
+    ** URIs with parameters.  Hence, they can always be passed into
+    ** sqlite3_uri_parameter(). */
+    assert( (flags & SQLITE_OPEN_URI) || zName[strlen(zName)+1]==0 );
+
+  }else if( !zName ){
+    /* If zName is NULL, the upper layer is requesting a temp file. */
+    assert(isDelete && !syncDir);
+    rc = unixGetTempname(pVfs->mxPathname, zTmpname);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    zName = zTmpname;
+
+    /* Generated temporary filenames are always double-zero terminated
+    ** for use by sqlite3_uri_parameter(). */
+    assert( zName[strlen(zName)+1]==0 );
+  }
+
+  /* Determine the value of the flags parameter passed to POSIX function
+  ** open(). These must be calculated even if open() is not called, as
+  ** they may be stored as part of the file handle and used by the 
+  ** 'conch file' locking functions later on.  */
+  if( isReadonly )  openFlags |= O_RDONLY;
+  if( isReadWrite ) openFlags |= O_RDWR;
+  if( isCreate )    openFlags |= O_CREAT;
+  if( isExclusive ) openFlags |= (O_EXCL|O_NOFOLLOW);
+  openFlags |= (O_LARGEFILE|O_BINARY);
+
+  if( fd<0 ){
+    mode_t openMode;              /* Permissions to create file with */
+    uid_t uid;                    /* Userid for the file */
+    gid_t gid;                    /* Groupid for the file */
+    rc = findCreateFileMode(zName, flags, &openMode, &uid, &gid);
+    if( rc!=SQLITE_OK ){
+      assert( !p->pUnused );
+      assert( eType==SQLITE_OPEN_WAL || eType==SQLITE_OPEN_MAIN_JOURNAL );
+      return rc;
+    }
+    fd = robust_open(zName, openFlags, openMode);
+    OSTRACE(("OPENX   %-3d %s 0%o\n", fd, zName, openFlags));
+    assert( !isExclusive || (openFlags & O_CREAT)!=0 );
+    if( fd<0 && errno!=EISDIR && isReadWrite ){
+      /* Failed to open the file for read/write access. Try read-only. */
+      flags &= ~(SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE);
+      openFlags &= ~(O_RDWR|O_CREAT);
+      flags |= SQLITE_OPEN_READONLY;
+      openFlags |= O_RDONLY;
+      isReadonly = 1;
+      fd = robust_open(zName, openFlags, openMode);
+    }
+    if( fd<0 ){
+      rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zName);
+      goto open_finished;
+    }
+
+    /* If this process is running as root and if creating a new rollback
+    ** journal or WAL file, set the ownership of the journal or WAL to be
+    ** the same as the original database.
+    */
+    if( flags & (SQLITE_OPEN_WAL|SQLITE_OPEN_MAIN_JOURNAL) ){
+      robustFchown(fd, uid, gid);
+    }
+  }
+  assert( fd>=0 );
+  if( pOutFlags ){
+    *pOutFlags = flags;
+  }
+
+  if( p->pUnused ){
+    p->pUnused->fd = fd;
+    p->pUnused->flags = flags;
+  }
+
+  if( isDelete ){
+#if OS_VXWORKS
+    zPath = zName;
+#elif defined(SQLITE_UNLINK_AFTER_CLOSE)
+    zPath = sqlite3_mprintf("%s", zName);
+    if( zPath==0 ){
+      robust_close(p, fd, __LINE__);
+      return SQLITE_NOMEM_BKPT;
+    }
+#else
+    osUnlink(zName);
+#endif
+  }
+#if SQLITE_ENABLE_LOCKING_STYLE
+  else{
+    p->openFlags = openFlags;
+  }
+#endif
+  
+#if defined(__APPLE__) || SQLITE_ENABLE_LOCKING_STYLE
+  if( fstatfs(fd, &fsInfo) == -1 ){
+    storeLastErrno(p, errno);
+    robust_close(p, fd, __LINE__);
+    return SQLITE_IOERR_ACCESS;
+  }
+  if (0 == strncmp("msdos", fsInfo.f_fstypename, 5)) {
+    ((unixFile*)pFile)->fsFlags |= SQLITE_FSFLAGS_IS_MSDOS;
+  }
+  if (0 == strncmp("exfat", fsInfo.f_fstypename, 5)) {
+    ((unixFile*)pFile)->fsFlags |= SQLITE_FSFLAGS_IS_MSDOS;
+  }
+#endif
+
+  /* Set up appropriate ctrlFlags */
+  if( isDelete )                ctrlFlags |= UNIXFILE_DELETE;
+  if( isReadonly )              ctrlFlags |= UNIXFILE_RDONLY;
+  noLock = eType!=SQLITE_OPEN_MAIN_DB;
+  if( noLock )                  ctrlFlags |= UNIXFILE_NOLOCK;
+  if( syncDir )                 ctrlFlags |= UNIXFILE_DIRSYNC;
+  if( flags & SQLITE_OPEN_URI ) ctrlFlags |= UNIXFILE_URI;
+
+#if SQLITE_ENABLE_LOCKING_STYLE
+#if SQLITE_PREFER_PROXY_LOCKING
+  isAutoProxy = 1;
+#endif
+  if( isAutoProxy && (zPath!=NULL) && (!noLock) && pVfs->xOpen ){
+    char *envforce = getenv("SQLITE_FORCE_PROXY_LOCKING");
+    int useProxy = 0;
+
+    /* SQLITE_FORCE_PROXY_LOCKING==1 means force always use proxy, 0 means 
+    ** never use proxy, NULL means use proxy for non-local files only.  */
+    if( envforce!=NULL ){
+      useProxy = atoi(envforce)>0;
+    }else{
+      useProxy = !(fsInfo.f_flags&MNT_LOCAL);
+    }
+    if( useProxy ){
+      rc = fillInUnixFile(pVfs, fd, pFile, zPath, ctrlFlags);
+      if( rc==SQLITE_OK ){
+        rc = proxyTransformUnixFile((unixFile*)pFile, ":auto:");
+        if( rc!=SQLITE_OK ){
+          /* Use unixClose to clean up the resources added in fillInUnixFile 
+          ** and clear all the structure's references.  Specifically, 
+          ** pFile->pMethods will be NULL so sqlite3OsClose will be a no-op 
+          */
+          unixClose(pFile);
+          return rc;
+        }
+      }
+      goto open_finished;
+    }
+  }
+#endif
+  
+  rc = fillInUnixFile(pVfs, fd, pFile, zPath, ctrlFlags);
+
+open_finished:
+  if( rc!=SQLITE_OK ){
+    sqlite3_free(p->pUnused);
+  }
+  return rc;
+}
+
+
+/*
+** Delete the file at zPath. If the dirSync argument is true, fsync()
+** the directory after deleting the file.
+*/
+static int unixDelete(
+  sqlite3_vfs *NotUsed,     /* VFS containing this as the xDelete method */
+  const char *zPath,        /* Name of file to be deleted */
+  int dirSync               /* If true, fsync() directory after deleting file */
+){
+  int rc = SQLITE_OK;
+  UNUSED_PARAMETER(NotUsed);
+  SimulateIOError(return SQLITE_IOERR_DELETE);
+  if( osUnlink(zPath)==(-1) ){
+    if( errno==ENOENT
+#if OS_VXWORKS
+        || osAccess(zPath,0)!=0
+#endif
+    ){
+      rc = SQLITE_IOERR_DELETE_NOENT;
+    }else{
+      rc = unixLogError(SQLITE_IOERR_DELETE, "unlink", zPath);
+    }
+    return rc;
+  }
+#ifndef SQLITE_DISABLE_DIRSYNC
+  if( (dirSync & 1)!=0 ){
+    int fd;
+    rc = osOpenDirectory(zPath, &fd);
+    if( rc==SQLITE_OK ){
+      if( full_fsync(fd,0,0) ){
+        rc = unixLogError(SQLITE_IOERR_DIR_FSYNC, "fsync", zPath);
+      }
+      robust_close(0, fd, __LINE__);
+    }else{
+      assert( rc==SQLITE_CANTOPEN );
+      rc = SQLITE_OK;
+    }
+  }
+#endif
+  return rc;
+}
+
+/*
+** Test the existence of or access permissions of file zPath. The
+** test performed depends on the value of flags:
+**
+**     SQLITE_ACCESS_EXISTS: Return 1 if the file exists
+**     SQLITE_ACCESS_READWRITE: Return 1 if the file is read and writable.
+**     SQLITE_ACCESS_READONLY: Return 1 if the file is readable.
+**
+** Otherwise return 0.
+*/
+static int unixAccess(
+  sqlite3_vfs *NotUsed,   /* The VFS containing this xAccess method */
+  const char *zPath,      /* Path of the file to examine */
+  int flags,              /* What do we want to learn about the zPath file? */
+  int *pResOut            /* Write result boolean here */
+){
+  UNUSED_PARAMETER(NotUsed);
+  SimulateIOError( return SQLITE_IOERR_ACCESS; );
+  assert( pResOut!=0 );
+
+  /* The spec says there are three possible values for flags.  But only
+  ** two of them are actually used */
+  assert( flags==SQLITE_ACCESS_EXISTS || flags==SQLITE_ACCESS_READWRITE );
+
+  if( flags==SQLITE_ACCESS_EXISTS ){
+    struct stat buf;
+    *pResOut = (0==osStat(zPath, &buf) && buf.st_size>0);
+  }else{
+    *pResOut = osAccess(zPath, W_OK|R_OK)==0;
+  }
+  return SQLITE_OK;
+}
+
+/*
+**
+*/
+static int mkFullPathname(
+  const char *zPath,              /* Input path */
+  char *zOut,                     /* Output buffer */
+  int nOut                        /* Allocated size of buffer zOut */
+){
+  int nPath = sqlite3Strlen30(zPath);
+  int iOff = 0;
+  if( zPath[0]!='/' ){
+    if( osGetcwd(zOut, nOut-2)==0 ){
+      return unixLogError(SQLITE_CANTOPEN_BKPT, "getcwd", zPath);
+    }
+    iOff = sqlite3Strlen30(zOut);
+    zOut[iOff++] = '/';
+  }
+  if( (iOff+nPath+1)>nOut ){
+    /* SQLite assumes that xFullPathname() nul-terminates the output buffer
+    ** even if it returns an error.  */
+    zOut[iOff] = '\0';
+    return SQLITE_CANTOPEN_BKPT;
+  }
+  sqlite3_snprintf(nOut-iOff, &zOut[iOff], "%s", zPath);
+  return SQLITE_OK;
+}
+
+/*
+** Turn a relative pathname into a full pathname. The relative path
+** is stored as a nul-terminated string in the buffer pointed to by
+** zPath. 
+**
+** zOut points to a buffer of at least sqlite3_vfs.mxPathname bytes 
+** (in this case, MAX_PATHNAME bytes). The full-path is written to
+** this buffer before returning.
+*/
+static int unixFullPathname(
+  sqlite3_vfs *pVfs,            /* Pointer to vfs object */
+  const char *zPath,            /* Possibly relative input path */
+  int nOut,                     /* Size of output buffer in bytes */
+  char *zOut                    /* Output buffer */
+){
+#if !defined(HAVE_READLINK) || !defined(HAVE_LSTAT)
+  return mkFullPathname(zPath, zOut, nOut);
+#else
+  int rc = SQLITE_OK;
+  int nByte;
+  int nLink = 1;                /* Number of symbolic links followed so far */
+  const char *zIn = zPath;      /* Input path for each iteration of loop */
+  char *zDel = 0;
+
+  assert( pVfs->mxPathname==MAX_PATHNAME );
+  UNUSED_PARAMETER(pVfs);
+
+  /* It's odd to simulate an io-error here, but really this is just
+  ** using the io-error infrastructure to test that SQLite handles this
+  ** function failing. This function could fail if, for example, the
+  ** current working directory has been unlinked.
+  */
+  SimulateIOError( return SQLITE_ERROR );
+
+  do {
+
+    /* Call stat() on path zIn. Set bLink to true if the path is a symbolic
+    ** link, or false otherwise.  */
+    int bLink = 0;
+    struct stat buf;
+    if( osLstat(zIn, &buf)!=0 ){
+      if( errno!=ENOENT ){
+        rc = unixLogError(SQLITE_CANTOPEN_BKPT, "lstat", zIn);
+      }
+    }else{
+      bLink = S_ISLNK(buf.st_mode);
+    }
+
+    if( bLink ){
+      if( zDel==0 ){
+        zDel = sqlite3_malloc(nOut);
+        if( zDel==0 ) rc = SQLITE_NOMEM_BKPT;
+      }else if( ++nLink>SQLITE_MAX_SYMLINKS ){
+        rc = SQLITE_CANTOPEN_BKPT;
+      }
+
+      if( rc==SQLITE_OK ){
+        nByte = osReadlink(zIn, zDel, nOut-1);
+        if( nByte<0 ){
+          rc = unixLogError(SQLITE_CANTOPEN_BKPT, "readlink", zIn);
+        }else{
+          if( zDel[0]!='/' ){
+            int n;
+            for(n = sqlite3Strlen30(zIn); n>0 && zIn[n-1]!='/'; n--);
+            if( nByte+n+1>nOut ){
+              rc = SQLITE_CANTOPEN_BKPT;
+            }else{
+              memmove(&zDel[n], zDel, nByte+1);
+              memcpy(zDel, zIn, n);
+              nByte += n;
+            }
+          }
+          zDel[nByte] = '\0';
+        }
+      }
+
+      zIn = zDel;
+    }
+
+    assert( rc!=SQLITE_OK || zIn!=zOut || zIn[0]=='/' );
+    if( rc==SQLITE_OK && zIn!=zOut ){
+      rc = mkFullPathname(zIn, zOut, nOut);
+    }
+    if( bLink==0 ) break;
+    zIn = zOut;
+  }while( rc==SQLITE_OK );
+
+  sqlite3_free(zDel);
+  return rc;
+#endif   /* HAVE_READLINK && HAVE_LSTAT */
+}
+
+
+#ifndef SQLITE_OMIT_LOAD_EXTENSION
+/*
+** Interfaces for opening a shared library, finding entry points
+** within the shared library, and closing the shared library.
+*/
+#include <dlfcn.h>
+static void *unixDlOpen(sqlite3_vfs *NotUsed, const char *zFilename){
+  UNUSED_PARAMETER(NotUsed);
+  return dlopen(zFilename, RTLD_NOW | RTLD_GLOBAL);
+}
+
+/*
+** SQLite calls this function immediately after a call to unixDlSym() or
+** unixDlOpen() fails (returns a null pointer). If a more detailed error
+** message is available, it is written to zBufOut. If no error message
+** is available, zBufOut is left unmodified and SQLite uses a default
+** error message.
+*/
+static void unixDlError(sqlite3_vfs *NotUsed, int nBuf, char *zBufOut){
+  const char *zErr;
+  UNUSED_PARAMETER(NotUsed);
+  unixEnterMutex();
+  zErr = dlerror();
+  if( zErr ){
+    sqlite3_snprintf(nBuf, zBufOut, "%s", zErr);
+  }
+  unixLeaveMutex();
+}
+static void (*unixDlSym(sqlite3_vfs *NotUsed, void *p, const char*zSym))(void){
+  /* 
+  ** GCC with -pedantic-errors says that C90 does not allow a void* to be
+  ** cast into a pointer to a function.  And yet the library dlsym() routine
+  ** returns a void* which is really a pointer to a function.  So how do we
+  ** use dlsym() with -pedantic-errors?
+  **
+  ** Variable x below is defined to be a pointer to a function taking
+  ** parameters void* and const char* and returning a pointer to a function.
+  ** We initialize x by assigning it a pointer to the dlsym() function.
+  ** (That assignment requires a cast.)  Then we call the function that
+  ** x points to.  
+  **
+  ** This work-around is unlikely to work correctly on any system where
+  ** you really cannot cast a function pointer into void*.  But then, on the
+  ** other hand, dlsym() will not work on such a system either, so we have
+  ** not really lost anything.
+  */
+  void (*(*x)(void*,const char*))(void);
+  UNUSED_PARAMETER(NotUsed);
+  x = (void(*(*)(void*,const char*))(void))dlsym;
+  return (*x)(p, zSym);
+}
+static void unixDlClose(sqlite3_vfs *NotUsed, void *pHandle){
+  UNUSED_PARAMETER(NotUsed);
+  dlclose(pHandle);
+}
+#else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */
+  #define unixDlOpen  0
+  #define unixDlError 0
+  #define unixDlSym   0
+  #define unixDlClose 0
+#endif
+
+/*
+** Write nBuf bytes of random data to the supplied buffer zBuf.
+*/
+static int unixRandomness(sqlite3_vfs *NotUsed, int nBuf, char *zBuf){
+  UNUSED_PARAMETER(NotUsed);
+  assert((size_t)nBuf>=(sizeof(time_t)+sizeof(int)));
+
+  /* We have to initialize zBuf to prevent valgrind from reporting
+  ** errors.  The reports issued by valgrind are incorrect - we would
+  ** prefer that the randomness be increased by making use of the
+  ** uninitialized space in zBuf - but valgrind errors tend to worry
+  ** some users.  Rather than argue, it seems easier just to initialize
+  ** the whole array and silence valgrind, even if that means less randomness
+  ** in the random seed.
+  **
+  ** When testing, initializing zBuf[] to zero is all we do.  That means
+  ** that we always use the same random number sequence.  This makes the
+  ** tests repeatable.
+  */
+  memset(zBuf, 0, nBuf);
+  randomnessPid = osGetpid(0);  
+#if !defined(SQLITE_TEST) && !defined(SQLITE_OMIT_RANDOMNESS)
+  {
+    int fd, got;
+    fd = robust_open("/dev/urandom", O_RDONLY, 0);
+    if( fd<0 ){
+      time_t t;
+      time(&t);
+      memcpy(zBuf, &t, sizeof(t));
+      memcpy(&zBuf[sizeof(t)], &randomnessPid, sizeof(randomnessPid));
+      assert( sizeof(t)+sizeof(randomnessPid)<=(size_t)nBuf );
+      nBuf = sizeof(t) + sizeof(randomnessPid);
+    }else{
+      do{ got = osRead(fd, zBuf, nBuf); }while( got<0 && errno==EINTR );
+      robust_close(0, fd, __LINE__);
+    }
+  }
+#endif
+  return nBuf;
+}
+
+
+/*
+** Sleep for a little while.  Return the amount of time slept.
+** The argument is the number of microseconds we want to sleep.
+** The return value is the number of microseconds of sleep actually
+** requested from the underlying operating system, a number which
+** might be greater than or equal to the argument, but not less
+** than the argument.
+*/
+static int unixSleep(sqlite3_vfs *NotUsed, int microseconds){
+#if OS_VXWORKS
+  struct timespec sp;
+
+  sp.tv_sec = microseconds / 1000000;
+  sp.tv_nsec = (microseconds % 1000000) * 1000;
+  nanosleep(&sp, NULL);
+  UNUSED_PARAMETER(NotUsed);
+  return microseconds;
+#elif defined(HAVE_USLEEP) && HAVE_USLEEP
+  usleep(microseconds);
+  UNUSED_PARAMETER(NotUsed);
+  return microseconds;
+#else
+  int seconds = (microseconds+999999)/1000000;
+  sleep(seconds);
+  UNUSED_PARAMETER(NotUsed);
+  return seconds*1000000;
+#endif
+}
+
+/*
+** The following variable, if set to a non-zero value, is interpreted as
+** the number of seconds since 1970 and is used to set the result of
+** sqlite3OsCurrentTime() during testing.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_current_time = 0;  /* Fake system time in seconds since 1970. */
+#endif
+
+/*
+** Find the current time (in Universal Coordinated Time).  Write into *piNow
+** the current time and date as a Julian Day number times 86_400_000.  In
+** other words, write into *piNow the number of milliseconds since the Julian
+** epoch of noon in Greenwich on November 24, 4714 B.C according to the
+** proleptic Gregorian calendar.
+**
+** On success, return SQLITE_OK.  Return SQLITE_ERROR if the time and date 
+** cannot be found.
+*/
+static int unixCurrentTimeInt64(sqlite3_vfs *NotUsed, sqlite3_int64 *piNow){
+  static const sqlite3_int64 unixEpoch = 24405875*(sqlite3_int64)8640000;
+  int rc = SQLITE_OK;
+#if defined(NO_GETTOD)
+  time_t t;
+  time(&t);
+  *piNow = ((sqlite3_int64)t)*1000 + unixEpoch;
+#elif OS_VXWORKS
+  struct timespec sNow;
+  clock_gettime(CLOCK_REALTIME, &sNow);
+  *piNow = unixEpoch + 1000*(sqlite3_int64)sNow.tv_sec + sNow.tv_nsec/1000000;
+#else
+  struct timeval sNow;
+  (void)gettimeofday(&sNow, 0);  /* Cannot fail given valid arguments */
+  *piNow = unixEpoch + 1000*(sqlite3_int64)sNow.tv_sec + sNow.tv_usec/1000;
+#endif
+
+#ifdef SQLITE_TEST
+  if( sqlite3_current_time ){
+    *piNow = 1000*(sqlite3_int64)sqlite3_current_time + unixEpoch;
+  }
+#endif
+  UNUSED_PARAMETER(NotUsed);
+  return rc;
+}
+
+#ifndef SQLITE_OMIT_DEPRECATED
+/*
+** Find the current time (in Universal Coordinated Time).  Write the
+** current time and date as a Julian Day number into *prNow and
+** return 0.  Return 1 if the time and date cannot be found.
+*/
+static int unixCurrentTime(sqlite3_vfs *NotUsed, double *prNow){
+  sqlite3_int64 i = 0;
+  int rc;
+  UNUSED_PARAMETER(NotUsed);
+  rc = unixCurrentTimeInt64(0, &i);
+  *prNow = i/86400000.0;
+  return rc;
+}
+#else
+# define unixCurrentTime 0
+#endif
+
+/*
+** The xGetLastError() method is designed to return a better
+** low-level error message when operating-system problems come up
+** during SQLite operation.  Only the integer return code is currently
+** used.
+*/
+static int unixGetLastError(sqlite3_vfs *NotUsed, int NotUsed2, char *NotUsed3){
+  UNUSED_PARAMETER(NotUsed);
+  UNUSED_PARAMETER(NotUsed2);
+  UNUSED_PARAMETER(NotUsed3);
+  return errno;
+}
+
+
+/*
+************************ End of sqlite3_vfs methods ***************************
+******************************************************************************/
+
+/******************************************************************************
+************************** Begin Proxy Locking ********************************
+**
+** Proxy locking is a "uber-locking-method" in this sense:  It uses the
+** other locking methods on secondary lock files.  Proxy locking is a
+** meta-layer over top of the primitive locking implemented above.  For
+** this reason, the division that implements of proxy locking is deferred
+** until late in the file (here) after all of the other I/O methods have
+** been defined - so that the primitive locking methods are available
+** as services to help with the implementation of proxy locking.
+**
+****
+**
+** The default locking schemes in SQLite use byte-range locks on the
+** database file to coordinate safe, concurrent access by multiple readers
+** and writers [http://sqlite.org/lockingv3.html].  The five file locking
+** states (UNLOCKED, PENDING, SHARED, RESERVED, EXCLUSIVE) are implemented
+** as POSIX read & write locks over fixed set of locations (via fsctl),
+** on AFP and SMB only exclusive byte-range locks are available via fsctl
+** with _IOWR('z', 23, struct ByteRangeLockPB2) to track the same 5 states.
+** To simulate a F_RDLCK on the shared range, on AFP a randomly selected
+** address in the shared range is taken for a SHARED lock, the entire
+** shared range is taken for an EXCLUSIVE lock):
+**
+**      PENDING_BYTE        0x40000000
+**      RESERVED_BYTE       0x40000001
+**      SHARED_RANGE        0x40000002 -> 0x40000200
+**
+** This works well on the local file system, but shows a nearly 100x
+** slowdown in read performance on AFP because the AFP client disables
+** the read cache when byte-range locks are present.  Enabling the read
+** cache exposes a cache coherency problem that is present on all OS X
+** supported network file systems.  NFS and AFP both observe the
+** close-to-open semantics for ensuring cache coherency
+** [http://nfs.sourceforge.net/#faq_a8], which does not effectively
+** address the requirements for concurrent database access by multiple
+** readers and writers
+** [http://www.nabble.com/SQLite-on-NFS-cache-coherency-td15655701.html].
+**
+** To address the performance and cache coherency issues, proxy file locking
+** changes the way database access is controlled by limiting access to a
+** single host at a time and moving file locks off of the database file
+** and onto a proxy file on the local file system.  
+**
+**
+** Using proxy locks
+** -----------------
+**
+** C APIs
+**
+**  sqlite3_file_control(db, dbname, SQLITE_FCNTL_SET_LOCKPROXYFILE,
+**                       <proxy_path> | ":auto:");
+**  sqlite3_file_control(db, dbname, SQLITE_FCNTL_GET_LOCKPROXYFILE,
+**                       &<proxy_path>);
+**
+**
+** SQL pragmas
+**
+**  PRAGMA [database.]lock_proxy_file=<proxy_path> | :auto:
+**  PRAGMA [database.]lock_proxy_file
+**
+** Specifying ":auto:" means that if there is a conch file with a matching
+** host ID in it, the proxy path in the conch file will be used, otherwise
+** a proxy path based on the user's temp dir
+** (via confstr(_CS_DARWIN_USER_TEMP_DIR,...)) will be used and the
+** actual proxy file name is generated from the name and path of the
+** database file.  For example:
+**
+**       For database path "/Users/me/foo.db" 
+**       The lock path will be "<tmpdir>/sqliteplocks/_Users_me_foo.db:auto:")
+**
+** Once a lock proxy is configured for a database connection, it can not
+** be removed, however it may be switched to a different proxy path via
+** the above APIs (assuming the conch file is not being held by another
+** connection or process). 
+**
+**
+** How proxy locking works
+** -----------------------
+**
+** Proxy file locking relies primarily on two new supporting files: 
+**
+**   *  conch file to limit access to the database file to a single host
+**      at a time
+**
+**   *  proxy file to act as a proxy for the advisory locks normally
+**      taken on the database
+**
+** The conch file - to use a proxy file, sqlite must first "hold the conch"
+** by taking an sqlite-style shared lock on the conch file, reading the
+** contents and comparing the host's unique host ID (see below) and lock
+** proxy path against the values stored in the conch.  The conch file is
+** stored in the same directory as the database file and the file name
+** is patterned after the database file name as ".<databasename>-conch".
+** If the conch file does not exist, or its contents do not match the
+** host ID and/or proxy path, then the lock is escalated to an exclusive
+** lock and the conch file contents is updated with the host ID and proxy
+** path and the lock is downgraded to a shared lock again.  If the conch
+** is held by another process (with a shared lock), the exclusive lock
+** will fail and SQLITE_BUSY is returned.
+**
+** The proxy file - a single-byte file used for all advisory file locks
+** normally taken on the database file.   This allows for safe sharing
+** of the database file for multiple readers and writers on the same
+** host (the conch ensures that they all use the same local lock file).
+**
+** Requesting the lock proxy does not immediately take the conch, it is
+** only taken when the first request to lock database file is made.  
+** This matches the semantics of the traditional locking behavior, where
+** opening a connection to a database file does not take a lock on it.
+** The shared lock and an open file descriptor are maintained until 
+** the connection to the database is closed. 
+**
+** The proxy file and the lock file are never deleted so they only need
+** to be created the first time they are used.
+**
+** Configuration options
+** ---------------------
+**
+**  SQLITE_PREFER_PROXY_LOCKING
+**
+**       Database files accessed on non-local file systems are
+**       automatically configured for proxy locking, lock files are
+**       named automatically using the same logic as
+**       PRAGMA lock_proxy_file=":auto:"
+**    
+**  SQLITE_PROXY_DEBUG
+**
+**       Enables the logging of error messages during host id file
+**       retrieval and creation
+**
+**  LOCKPROXYDIR
+**
+**       Overrides the default directory used for lock proxy files that
+**       are named automatically via the ":auto:" setting
+**
+**  SQLITE_DEFAULT_PROXYDIR_PERMISSIONS
+**
+**       Permissions to use when creating a directory for storing the
+**       lock proxy files, only used when LOCKPROXYDIR is not set.
+**    
+**    
+** As mentioned above, when compiled with SQLITE_PREFER_PROXY_LOCKING,
+** setting the environment variable SQLITE_FORCE_PROXY_LOCKING to 1 will
+** force proxy locking to be used for every database file opened, and 0
+** will force automatic proxy locking to be disabled for all database
+** files (explicitly calling the SQLITE_FCNTL_SET_LOCKPROXYFILE pragma or
+** sqlite_file_control API is not affected by SQLITE_FORCE_PROXY_LOCKING).
+*/
+
+/*
+** Proxy locking is only available on MacOSX 
+*/
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+
+/*
+** The proxyLockingContext has the path and file structures for the remote 
+** and local proxy files in it
+*/
+typedef struct proxyLockingContext proxyLockingContext;
+struct proxyLockingContext {
+  unixFile *conchFile;         /* Open conch file */
+  char *conchFilePath;         /* Name of the conch file */
+  unixFile *lockProxy;         /* Open proxy lock file */
+  char *lockProxyPath;         /* Name of the proxy lock file */
+  char *dbPath;                /* Name of the open file */
+  int conchHeld;               /* 1 if the conch is held, -1 if lockless */
+  int nFails;                  /* Number of conch taking failures */
+  void *oldLockingContext;     /* Original lockingcontext to restore on close */
+  sqlite3_io_methods const *pOldMethod;     /* Original I/O methods for close */
+};
+
+/* 
+** The proxy lock file path for the database at dbPath is written into lPath, 
+** which must point to valid, writable memory large enough for a maxLen length
+** file path. 
+*/
+static int proxyGetLockPath(const char *dbPath, char *lPath, size_t maxLen){
+  int len;
+  int dbLen;
+  int i;
+
+#ifdef LOCKPROXYDIR
+  len = strlcpy(lPath, LOCKPROXYDIR, maxLen);
+#else
+# ifdef _CS_DARWIN_USER_TEMP_DIR
+  {
+    if( !confstr(_CS_DARWIN_USER_TEMP_DIR, lPath, maxLen) ){
+      OSTRACE(("GETLOCKPATH  failed %s errno=%d pid=%d\n",
+               lPath, errno, osGetpid(0)));
+      return SQLITE_IOERR_LOCK;
+    }
+    len = strlcat(lPath, "sqliteplocks", maxLen);    
+  }
+# else
+  len = strlcpy(lPath, "/tmp/", maxLen);
+# endif
+#endif
+
+  if( lPath[len-1]!='/' ){
+    len = strlcat(lPath, "/", maxLen);
+  }
+  
+  /* transform the db path to a unique cache name */
+  dbLen = (int)strlen(dbPath);
+  for( i=0; i<dbLen && (i+len+7)<(int)maxLen; i++){
+    char c = dbPath[i];
+    lPath[i+len] = (c=='/')?'_':c;
+  }
+  lPath[i+len]='\0';
+  strlcat(lPath, ":auto:", maxLen);
+  OSTRACE(("GETLOCKPATH  proxy lock path=%s pid=%d\n", lPath, osGetpid(0)));
+  return SQLITE_OK;
+}
+
+/* 
+ ** Creates the lock file and any missing directories in lockPath
+ */
+static int proxyCreateLockPath(const char *lockPath){
+  int i, len;
+  char buf[MAXPATHLEN];
+  int start = 0;
+  
+  assert(lockPath!=NULL);
+  /* try to create all the intermediate directories */
+  len = (int)strlen(lockPath);
+  buf[0] = lockPath[0];
+  for( i=1; i<len; i++ ){
+    if( lockPath[i] == '/' && (i - start > 0) ){
+      /* only mkdir if leaf dir != "." or "/" or ".." */
+      if( i-start>2 || (i-start==1 && buf[start] != '.' && buf[start] != '/') 
+         || (i-start==2 && buf[start] != '.' && buf[start+1] != '.') ){
+        buf[i]='\0';
+        if( osMkdir(buf, SQLITE_DEFAULT_PROXYDIR_PERMISSIONS) ){
+          int err=errno;
+          if( err!=EEXIST ) {
+            OSTRACE(("CREATELOCKPATH  FAILED creating %s, "
+                     "'%s' proxy lock path=%s pid=%d\n",
+                     buf, strerror(err), lockPath, osGetpid(0)));
+            return err;
+          }
+        }
+      }
+      start=i+1;
+    }
+    buf[i] = lockPath[i];
+  }
+  OSTRACE(("CREATELOCKPATH  proxy lock path=%s pid=%d\n",lockPath,osGetpid(0)));
+  return 0;
+}
+
+/*
+** Create a new VFS file descriptor (stored in memory obtained from
+** sqlite3_malloc) and open the file named "path" in the file descriptor.
+**
+** The caller is responsible not only for closing the file descriptor
+** but also for freeing the memory associated with the file descriptor.
+*/
+static int proxyCreateUnixFile(
+    const char *path,        /* path for the new unixFile */
+    unixFile **ppFile,       /* unixFile created and returned by ref */
+    int islockfile           /* if non zero missing dirs will be created */
+) {
+  int fd = -1;
+  unixFile *pNew;
+  int rc = SQLITE_OK;
+  int openFlags = O_RDWR | O_CREAT;
+  sqlite3_vfs dummyVfs;
+  int terrno = 0;
+  UnixUnusedFd *pUnused = NULL;
+
+  /* 1. first try to open/create the file
+  ** 2. if that fails, and this is a lock file (not-conch), try creating
+  ** the parent directories and then try again.
+  ** 3. if that fails, try to open the file read-only
+  ** otherwise return BUSY (if lock file) or CANTOPEN for the conch file
+  */
+  pUnused = findReusableFd(path, openFlags);
+  if( pUnused ){
+    fd = pUnused->fd;
+  }else{
+    pUnused = sqlite3_malloc64(sizeof(*pUnused));
+    if( !pUnused ){
+      return SQLITE_NOMEM_BKPT;
+    }
+  }
+  if( fd<0 ){
+    fd = robust_open(path, openFlags, 0);
+    terrno = errno;
+    if( fd<0 && errno==ENOENT && islockfile ){
+      if( proxyCreateLockPath(path) == SQLITE_OK ){
+        fd = robust_open(path, openFlags, 0);
+      }
+    }
+  }
+  if( fd<0 ){
+    openFlags = O_RDONLY;
+    fd = robust_open(path, openFlags, 0);
+    terrno = errno;
+  }
+  if( fd<0 ){
+    if( islockfile ){
+      return SQLITE_BUSY;
+    }
+    switch (terrno) {
+      case EACCES:
+        return SQLITE_PERM;
+      case EIO: 
+        return SQLITE_IOERR_LOCK; /* even though it is the conch */
+      default:
+        return SQLITE_CANTOPEN_BKPT;
+    }
+  }
+  
+  pNew = (unixFile *)sqlite3_malloc64(sizeof(*pNew));
+  if( pNew==NULL ){
+    rc = SQLITE_NOMEM_BKPT;
+    goto end_create_proxy;
+  }
+  memset(pNew, 0, sizeof(unixFile));
+  pNew->openFlags = openFlags;
+  memset(&dummyVfs, 0, sizeof(dummyVfs));
+  dummyVfs.pAppData = (void*)&autolockIoFinder;
+  dummyVfs.zName = "dummy";
+  pUnused->fd = fd;
+  pUnused->flags = openFlags;
+  pNew->pUnused = pUnused;
+  
+  rc = fillInUnixFile(&dummyVfs, fd, (sqlite3_file*)pNew, path, 0);
+  if( rc==SQLITE_OK ){
+    *ppFile = pNew;
+    return SQLITE_OK;
+  }
+end_create_proxy:    
+  robust_close(pNew, fd, __LINE__);
+  sqlite3_free(pNew);
+  sqlite3_free(pUnused);
+  return rc;
+}
+
+#ifdef SQLITE_TEST
+/* simulate multiple hosts by creating unique hostid file paths */
+SQLITE_API int sqlite3_hostid_num = 0;
+#endif
+
+#define PROXY_HOSTIDLEN    16  /* conch file host id length */
+
+#ifdef HAVE_GETHOSTUUID
+/* Not always defined in the headers as it ought to be */
+extern int gethostuuid(uuid_t id, const struct timespec *wait);
+#endif
+
+/* get the host ID via gethostuuid(), pHostID must point to PROXY_HOSTIDLEN 
+** bytes of writable memory.
+*/
+static int proxyGetHostID(unsigned char *pHostID, int *pError){
+  assert(PROXY_HOSTIDLEN == sizeof(uuid_t));
+  memset(pHostID, 0, PROXY_HOSTIDLEN);
+#ifdef HAVE_GETHOSTUUID
+  {
+    struct timespec timeout = {1, 0}; /* 1 sec timeout */
+    if( gethostuuid(pHostID, &timeout) ){
+      int err = errno;
+      if( pError ){
+        *pError = err;
+      }
+      return SQLITE_IOERR;
+    }
+  }
+#else
+  UNUSED_PARAMETER(pError);
+#endif
+#ifdef SQLITE_TEST
+  /* simulate multiple hosts by creating unique hostid file paths */
+  if( sqlite3_hostid_num != 0){
+    pHostID[0] = (char)(pHostID[0] + (char)(sqlite3_hostid_num & 0xFF));
+  }
+#endif
+  
+  return SQLITE_OK;
+}
+
+/* The conch file contains the header, host id and lock file path
+ */
+#define PROXY_CONCHVERSION 2   /* 1-byte header, 16-byte host id, path */
+#define PROXY_HEADERLEN    1   /* conch file header length */
+#define PROXY_PATHINDEX    (PROXY_HEADERLEN+PROXY_HOSTIDLEN)
+#define PROXY_MAXCONCHLEN  (PROXY_HEADERLEN+PROXY_HOSTIDLEN+MAXPATHLEN)
+
+/* 
+** Takes an open conch file, copies the contents to a new path and then moves 
+** it back.  The newly created file's file descriptor is assigned to the
+** conch file structure and finally the original conch file descriptor is 
+** closed.  Returns zero if successful.
+*/
+static int proxyBreakConchLock(unixFile *pFile, uuid_t myHostID){
+  proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; 
+  unixFile *conchFile = pCtx->conchFile;
+  char tPath[MAXPATHLEN];
+  char buf[PROXY_MAXCONCHLEN];
+  char *cPath = pCtx->conchFilePath;
+  size_t readLen = 0;
+  size_t pathLen = 0;
+  char errmsg[64] = "";
+  int fd = -1;
+  int rc = -1;
+  UNUSED_PARAMETER(myHostID);
+
+  /* create a new path by replace the trailing '-conch' with '-break' */
+  pathLen = strlcpy(tPath, cPath, MAXPATHLEN);
+  if( pathLen>MAXPATHLEN || pathLen<6 || 
+     (strlcpy(&tPath[pathLen-5], "break", 6) != 5) ){
+    sqlite3_snprintf(sizeof(errmsg),errmsg,"path error (len %d)",(int)pathLen);
+    goto end_breaklock;
+  }
+  /* read the conch content */
+  readLen = osPread(conchFile->h, buf, PROXY_MAXCONCHLEN, 0);
+  if( readLen<PROXY_PATHINDEX ){
+    sqlite3_snprintf(sizeof(errmsg),errmsg,"read error (len %d)",(int)readLen);
+    goto end_breaklock;
+  }
+  /* write it out to the temporary break file */
+  fd = robust_open(tPath, (O_RDWR|O_CREAT|O_EXCL), 0);
+  if( fd<0 ){
+    sqlite3_snprintf(sizeof(errmsg), errmsg, "create failed (%d)", errno);
+    goto end_breaklock;
+  }
+  if( osPwrite(fd, buf, readLen, 0) != (ssize_t)readLen ){
+    sqlite3_snprintf(sizeof(errmsg), errmsg, "write failed (%d)", errno);
+    goto end_breaklock;
+  }
+  if( rename(tPath, cPath) ){
+    sqlite3_snprintf(sizeof(errmsg), errmsg, "rename failed (%d)", errno);
+    goto end_breaklock;
+  }
+  rc = 0;
+  fprintf(stderr, "broke stale lock on %s\n", cPath);
+  robust_close(pFile, conchFile->h, __LINE__);
+  conchFile->h = fd;
+  conchFile->openFlags = O_RDWR | O_CREAT;
+
+end_breaklock:
+  if( rc ){
+    if( fd>=0 ){
+      osUnlink(tPath);
+      robust_close(pFile, fd, __LINE__);
+    }
+    fprintf(stderr, "failed to break stale lock on %s, %s\n", cPath, errmsg);
+  }
+  return rc;
+}
+
+/* Take the requested lock on the conch file and break a stale lock if the 
+** host id matches.
+*/
+static int proxyConchLock(unixFile *pFile, uuid_t myHostID, int lockType){
+  proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; 
+  unixFile *conchFile = pCtx->conchFile;
+  int rc = SQLITE_OK;
+  int nTries = 0;
+  struct timespec conchModTime;
+  
+  memset(&conchModTime, 0, sizeof(conchModTime));
+  do {
+    rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, lockType);
+    nTries ++;
+    if( rc==SQLITE_BUSY ){
+      /* If the lock failed (busy):
+       * 1st try: get the mod time of the conch, wait 0.5s and try again. 
+       * 2nd try: fail if the mod time changed or host id is different, wait 
+       *           10 sec and try again
+       * 3rd try: break the lock unless the mod time has changed.
+       */
+      struct stat buf;
+      if( osFstat(conchFile->h, &buf) ){
+        storeLastErrno(pFile, errno);
+        return SQLITE_IOERR_LOCK;
+      }
+      
+      if( nTries==1 ){
+        conchModTime = buf.st_mtimespec;
+        usleep(500000); /* wait 0.5 sec and try the lock again*/
+        continue;  
+      }
+
+      assert( nTries>1 );
+      if( conchModTime.tv_sec != buf.st_mtimespec.tv_sec || 
+         conchModTime.tv_nsec != buf.st_mtimespec.tv_nsec ){
+        return SQLITE_BUSY;
+      }
+      
+      if( nTries==2 ){  
+        char tBuf[PROXY_MAXCONCHLEN];
+        int len = osPread(conchFile->h, tBuf, PROXY_MAXCONCHLEN, 0);
+        if( len<0 ){
+          storeLastErrno(pFile, errno);
+          return SQLITE_IOERR_LOCK;
+        }
+        if( len>PROXY_PATHINDEX && tBuf[0]==(char)PROXY_CONCHVERSION){
+          /* don't break the lock if the host id doesn't match */
+          if( 0!=memcmp(&tBuf[PROXY_HEADERLEN], myHostID, PROXY_HOSTIDLEN) ){
+            return SQLITE_BUSY;
+          }
+        }else{
+          /* don't break the lock on short read or a version mismatch */
+          return SQLITE_BUSY;
+        }
+        usleep(10000000); /* wait 10 sec and try the lock again */
+        continue; 
+      }
+      
+      assert( nTries==3 );
+      if( 0==proxyBreakConchLock(pFile, myHostID) ){
+        rc = SQLITE_OK;
+        if( lockType==EXCLUSIVE_LOCK ){
+          rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, SHARED_LOCK);
+        }
+        if( !rc ){
+          rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, lockType);
+        }
+      }
+    }
+  } while( rc==SQLITE_BUSY && nTries<3 );
+  
+  return rc;
+}
+
+/* Takes the conch by taking a shared lock and read the contents conch, if 
+** lockPath is non-NULL, the host ID and lock file path must match.  A NULL 
+** lockPath means that the lockPath in the conch file will be used if the 
+** host IDs match, or a new lock path will be generated automatically 
+** and written to the conch file.
+*/
+static int proxyTakeConch(unixFile *pFile){
+  proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; 
+  
+  if( pCtx->conchHeld!=0 ){
+    return SQLITE_OK;
+  }else{
+    unixFile *conchFile = pCtx->conchFile;
+    uuid_t myHostID;
+    int pError = 0;
+    char readBuf[PROXY_MAXCONCHLEN];
+    char lockPath[MAXPATHLEN];
+    char *tempLockPath = NULL;
+    int rc = SQLITE_OK;
+    int createConch = 0;
+    int hostIdMatch = 0;
+    int readLen = 0;
+    int tryOldLockPath = 0;
+    int forceNewLockPath = 0;
+    
+    OSTRACE(("TAKECONCH  %d for %s pid=%d\n", conchFile->h,
+             (pCtx->lockProxyPath ? pCtx->lockProxyPath : ":auto:"),
+             osGetpid(0)));
+
+    rc = proxyGetHostID(myHostID, &pError);
+    if( (rc&0xff)==SQLITE_IOERR ){
+      storeLastErrno(pFile, pError);
+      goto end_takeconch;
+    }
+    rc = proxyConchLock(pFile, myHostID, SHARED_LOCK);
+    if( rc!=SQLITE_OK ){
+      goto end_takeconch;
+    }
+    /* read the existing conch file */
+    readLen = seekAndRead((unixFile*)conchFile, 0, readBuf, PROXY_MAXCONCHLEN);
+    if( readLen<0 ){
+      /* I/O error: lastErrno set by seekAndRead */
+      storeLastErrno(pFile, conchFile->lastErrno);
+      rc = SQLITE_IOERR_READ;
+      goto end_takeconch;
+    }else if( readLen<=(PROXY_HEADERLEN+PROXY_HOSTIDLEN) || 
+             readBuf[0]!=(char)PROXY_CONCHVERSION ){
+      /* a short read or version format mismatch means we need to create a new 
+      ** conch file. 
+      */
+      createConch = 1;
+    }
+    /* if the host id matches and the lock path already exists in the conch
+    ** we'll try to use the path there, if we can't open that path, we'll 
+    ** retry with a new auto-generated path 
+    */
+    do { /* in case we need to try again for an :auto: named lock file */
+
+      if( !createConch && !forceNewLockPath ){
+        hostIdMatch = !memcmp(&readBuf[PROXY_HEADERLEN], myHostID, 
+                                  PROXY_HOSTIDLEN);
+        /* if the conch has data compare the contents */
+        if( !pCtx->lockProxyPath ){
+          /* for auto-named local lock file, just check the host ID and we'll
+           ** use the local lock file path that's already in there
+           */
+          if( hostIdMatch ){
+            size_t pathLen = (readLen - PROXY_PATHINDEX);
+            
+            if( pathLen>=MAXPATHLEN ){
+              pathLen=MAXPATHLEN-1;
+            }
+            memcpy(lockPath, &readBuf[PROXY_PATHINDEX], pathLen);
+            lockPath[pathLen] = 0;
+            tempLockPath = lockPath;
+            tryOldLockPath = 1;
+            /* create a copy of the lock path if the conch is taken */
+            goto end_takeconch;
+          }
+        }else if( hostIdMatch
+               && !strncmp(pCtx->lockProxyPath, &readBuf[PROXY_PATHINDEX],
+                           readLen-PROXY_PATHINDEX)
+        ){
+          /* conch host and lock path match */
+          goto end_takeconch; 
+        }
+      }
+      
+      /* if the conch isn't writable and doesn't match, we can't take it */
+      if( (conchFile->openFlags&O_RDWR) == 0 ){
+        rc = SQLITE_BUSY;
+        goto end_takeconch;
+      }
+      
+      /* either the conch didn't match or we need to create a new one */
+      if( !pCtx->lockProxyPath ){
+        proxyGetLockPath(pCtx->dbPath, lockPath, MAXPATHLEN);
+        tempLockPath = lockPath;
+        /* create a copy of the lock path _only_ if the conch is taken */
+      }
+      
+      /* update conch with host and path (this will fail if other process
+      ** has a shared lock already), if the host id matches, use the big
+      ** stick.
+      */
+      futimes(conchFile->h, NULL);
+      if( hostIdMatch && !createConch ){
+        if( conchFile->pInode && conchFile->pInode->nShared>1 ){
+          /* We are trying for an exclusive lock but another thread in this
+           ** same process is still holding a shared lock. */
+          rc = SQLITE_BUSY;
+        } else {          
+          rc = proxyConchLock(pFile, myHostID, EXCLUSIVE_LOCK);
+        }
+      }else{
+        rc = proxyConchLock(pFile, myHostID, EXCLUSIVE_LOCK);
+      }
+      if( rc==SQLITE_OK ){
+        char writeBuffer[PROXY_MAXCONCHLEN];
+        int writeSize = 0;
+        
+        writeBuffer[0] = (char)PROXY_CONCHVERSION;
+        memcpy(&writeBuffer[PROXY_HEADERLEN], myHostID, PROXY_HOSTIDLEN);
+        if( pCtx->lockProxyPath!=NULL ){
+          strlcpy(&writeBuffer[PROXY_PATHINDEX], pCtx->lockProxyPath,
+                  MAXPATHLEN);
+        }else{
+          strlcpy(&writeBuffer[PROXY_PATHINDEX], tempLockPath, MAXPATHLEN);
+        }
+        writeSize = PROXY_PATHINDEX + strlen(&writeBuffer[PROXY_PATHINDEX]);
+        robust_ftruncate(conchFile->h, writeSize);
+        rc = unixWrite((sqlite3_file *)conchFile, writeBuffer, writeSize, 0);
+        full_fsync(conchFile->h,0,0);
+        /* If we created a new conch file (not just updated the contents of a 
+         ** valid conch file), try to match the permissions of the database 
+         */
+        if( rc==SQLITE_OK && createConch ){
+          struct stat buf;
+          int err = osFstat(pFile->h, &buf);
+          if( err==0 ){
+            mode_t cmode = buf.st_mode&(S_IRUSR|S_IWUSR | S_IRGRP|S_IWGRP |
+                                        S_IROTH|S_IWOTH);
+            /* try to match the database file R/W permissions, ignore failure */
+#ifndef SQLITE_PROXY_DEBUG
+            osFchmod(conchFile->h, cmode);
+#else
+            do{
+              rc = osFchmod(conchFile->h, cmode);
+            }while( rc==(-1) && errno==EINTR );
+            if( rc!=0 ){
+              int code = errno;
+              fprintf(stderr, "fchmod %o FAILED with %d %s\n",
+                      cmode, code, strerror(code));
+            } else {
+              fprintf(stderr, "fchmod %o SUCCEDED\n",cmode);
+            }
+          }else{
+            int code = errno;
+            fprintf(stderr, "STAT FAILED[%d] with %d %s\n", 
+                    err, code, strerror(code));
+#endif
+          }
+        }
+      }
+      conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, SHARED_LOCK);
+      
+    end_takeconch:
+      OSTRACE(("TRANSPROXY: CLOSE  %d\n", pFile->h));
+      if( rc==SQLITE_OK && pFile->openFlags ){
+        int fd;
+        if( pFile->h>=0 ){
+          robust_close(pFile, pFile->h, __LINE__);
+        }
+        pFile->h = -1;
+        fd = robust_open(pCtx->dbPath, pFile->openFlags, 0);
+        OSTRACE(("TRANSPROXY: OPEN  %d\n", fd));
+        if( fd>=0 ){
+          pFile->h = fd;
+        }else{
+          rc=SQLITE_CANTOPEN_BKPT; /* SQLITE_BUSY? proxyTakeConch called
+           during locking */
+        }
+      }
+      if( rc==SQLITE_OK && !pCtx->lockProxy ){
+        char *path = tempLockPath ? tempLockPath : pCtx->lockProxyPath;
+        rc = proxyCreateUnixFile(path, &pCtx->lockProxy, 1);
+        if( rc!=SQLITE_OK && rc!=SQLITE_NOMEM && tryOldLockPath ){
+          /* we couldn't create the proxy lock file with the old lock file path
+           ** so try again via auto-naming 
+           */
+          forceNewLockPath = 1;
+          tryOldLockPath = 0;
+          continue; /* go back to the do {} while start point, try again */
+        }
+      }
+      if( rc==SQLITE_OK ){
+        /* Need to make a copy of path if we extracted the value
+         ** from the conch file or the path was allocated on the stack
+         */
+        if( tempLockPath ){
+          pCtx->lockProxyPath = sqlite3DbStrDup(0, tempLockPath);
+          if( !pCtx->lockProxyPath ){
+            rc = SQLITE_NOMEM_BKPT;
+          }
+        }
+      }
+      if( rc==SQLITE_OK ){
+        pCtx->conchHeld = 1;
+        
+        if( pCtx->lockProxy->pMethod == &afpIoMethods ){
+          afpLockingContext *afpCtx;
+          afpCtx = (afpLockingContext *)pCtx->lockProxy->lockingContext;
+          afpCtx->dbPath = pCtx->lockProxyPath;
+        }
+      } else {
+        conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK);
+      }
+      OSTRACE(("TAKECONCH  %d %s\n", conchFile->h,
+               rc==SQLITE_OK?"ok":"failed"));
+      return rc;
+    } while (1); /* in case we need to retry the :auto: lock file - 
+                 ** we should never get here except via the 'continue' call. */
+  }
+}
+
+/*
+** If pFile holds a lock on a conch file, then release that lock.
+*/
+static int proxyReleaseConch(unixFile *pFile){
+  int rc = SQLITE_OK;         /* Subroutine return code */
+  proxyLockingContext *pCtx;  /* The locking context for the proxy lock */
+  unixFile *conchFile;        /* Name of the conch file */
+
+  pCtx = (proxyLockingContext *)pFile->lockingContext;
+  conchFile = pCtx->conchFile;
+  OSTRACE(("RELEASECONCH  %d for %s pid=%d\n", conchFile->h,
+           (pCtx->lockProxyPath ? pCtx->lockProxyPath : ":auto:"), 
+           osGetpid(0)));
+  if( pCtx->conchHeld>0 ){
+    rc = conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK);
+  }
+  pCtx->conchHeld = 0;
+  OSTRACE(("RELEASECONCH  %d %s\n", conchFile->h,
+           (rc==SQLITE_OK ? "ok" : "failed")));
+  return rc;
+}
+
+/*
+** Given the name of a database file, compute the name of its conch file.
+** Store the conch filename in memory obtained from sqlite3_malloc64().
+** Make *pConchPath point to the new name.  Return SQLITE_OK on success
+** or SQLITE_NOMEM if unable to obtain memory.
+**
+** The caller is responsible for ensuring that the allocated memory
+** space is eventually freed.
+**
+** *pConchPath is set to NULL if a memory allocation error occurs.
+*/
+static int proxyCreateConchPathname(char *dbPath, char **pConchPath){
+  int i;                        /* Loop counter */
+  int len = (int)strlen(dbPath); /* Length of database filename - dbPath */
+  char *conchPath;              /* buffer in which to construct conch name */
+
+  /* Allocate space for the conch filename and initialize the name to
+  ** the name of the original database file. */  
+  *pConchPath = conchPath = (char *)sqlite3_malloc64(len + 8);
+  if( conchPath==0 ){
+    return SQLITE_NOMEM_BKPT;
+  }
+  memcpy(conchPath, dbPath, len+1);
+  
+  /* now insert a "." before the last / character */
+  for( i=(len-1); i>=0; i-- ){
+    if( conchPath[i]=='/' ){
+      i++;
+      break;
+    }
+  }
+  conchPath[i]='.';
+  while ( i<len ){
+    conchPath[i+1]=dbPath[i];
+    i++;
+  }
+
+  /* append the "-conch" suffix to the file */
+  memcpy(&conchPath[i+1], "-conch", 7);
+  assert( (int)strlen(conchPath) == len+7 );
+
+  return SQLITE_OK;
+}
+
+
+/* Takes a fully configured proxy locking-style unix file and switches
+** the local lock file path 
+*/
+static int switchLockProxyPath(unixFile *pFile, const char *path) {
+  proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext;
+  char *oldPath = pCtx->lockProxyPath;
+  int rc = SQLITE_OK;
+
+  if( pFile->eFileLock!=NO_LOCK ){
+    return SQLITE_BUSY;
+  }  
+
+  /* nothing to do if the path is NULL, :auto: or matches the existing path */
+  if( !path || path[0]=='\0' || !strcmp(path, ":auto:") ||
+    (oldPath && !strncmp(oldPath, path, MAXPATHLEN)) ){
+    return SQLITE_OK;
+  }else{
+    unixFile *lockProxy = pCtx->lockProxy;
+    pCtx->lockProxy=NULL;
+    pCtx->conchHeld = 0;
+    if( lockProxy!=NULL ){
+      rc=lockProxy->pMethod->xClose((sqlite3_file *)lockProxy);
+      if( rc ) return rc;
+      sqlite3_free(lockProxy);
+    }
+    sqlite3_free(oldPath);
+    pCtx->lockProxyPath = sqlite3DbStrDup(0, path);
+  }
+  
+  return rc;
+}
+
+/*
+** pFile is a file that has been opened by a prior xOpen call.  dbPath
+** is a string buffer at least MAXPATHLEN+1 characters in size.
+**
+** This routine find the filename associated with pFile and writes it
+** int dbPath.
+*/
+static int proxyGetDbPathForUnixFile(unixFile *pFile, char *dbPath){
+#if defined(__APPLE__)
+  if( pFile->pMethod == &afpIoMethods ){
+    /* afp style keeps a reference to the db path in the filePath field 
+    ** of the struct */
+    assert( (int)strlen((char*)pFile->lockingContext)<=MAXPATHLEN );
+    strlcpy(dbPath, ((afpLockingContext *)pFile->lockingContext)->dbPath,
+            MAXPATHLEN);
+  } else
+#endif
+  if( pFile->pMethod == &dotlockIoMethods ){
+    /* dot lock style uses the locking context to store the dot lock
+    ** file path */
+    int len = strlen((char *)pFile->lockingContext) - strlen(DOTLOCK_SUFFIX);
+    memcpy(dbPath, (char *)pFile->lockingContext, len + 1);
+  }else{
+    /* all other styles use the locking context to store the db file path */
+    assert( strlen((char*)pFile->lockingContext)<=MAXPATHLEN );
+    strlcpy(dbPath, (char *)pFile->lockingContext, MAXPATHLEN);
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Takes an already filled in unix file and alters it so all file locking 
+** will be performed on the local proxy lock file.  The following fields
+** are preserved in the locking context so that they can be restored and 
+** the unix structure properly cleaned up at close time:
+**  ->lockingContext
+**  ->pMethod
+*/
+static int proxyTransformUnixFile(unixFile *pFile, const char *path) {
+  proxyLockingContext *pCtx;
+  char dbPath[MAXPATHLEN+1];       /* Name of the database file */
+  char *lockPath=NULL;
+  int rc = SQLITE_OK;
+  
+  if( pFile->eFileLock!=NO_LOCK ){
+    return SQLITE_BUSY;
+  }
+  proxyGetDbPathForUnixFile(pFile, dbPath);
+  if( !path || path[0]=='\0' || !strcmp(path, ":auto:") ){
+    lockPath=NULL;
+  }else{
+    lockPath=(char *)path;
+  }
+  
+  OSTRACE(("TRANSPROXY  %d for %s pid=%d\n", pFile->h,
+           (lockPath ? lockPath : ":auto:"), osGetpid(0)));
+
+  pCtx = sqlite3_malloc64( sizeof(*pCtx) );
+  if( pCtx==0 ){
+    return SQLITE_NOMEM_BKPT;
+  }
+  memset(pCtx, 0, sizeof(*pCtx));
+
+  rc = proxyCreateConchPathname(dbPath, &pCtx->conchFilePath);
+  if( rc==SQLITE_OK ){
+    rc = proxyCreateUnixFile(pCtx->conchFilePath, &pCtx->conchFile, 0);
+    if( rc==SQLITE_CANTOPEN && ((pFile->openFlags&O_RDWR) == 0) ){
+      /* if (a) the open flags are not O_RDWR, (b) the conch isn't there, and
+      ** (c) the file system is read-only, then enable no-locking access.
+      ** Ugh, since O_RDONLY==0x0000 we test for !O_RDWR since unixOpen asserts
+      ** that openFlags will have only one of O_RDONLY or O_RDWR.
+      */
+      struct statfs fsInfo;
+      struct stat conchInfo;
+      int goLockless = 0;
+
+      if( osStat(pCtx->conchFilePath, &conchInfo) == -1 ) {
+        int err = errno;
+        if( (err==ENOENT) && (statfs(dbPath, &fsInfo) != -1) ){
+          goLockless = (fsInfo.f_flags&MNT_RDONLY) == MNT_RDONLY;
+        }
+      }
+      if( goLockless ){
+        pCtx->conchHeld = -1; /* read only FS/ lockless */
+        rc = SQLITE_OK;
+      }
+    }
+  }  
+  if( rc==SQLITE_OK && lockPath ){
+    pCtx->lockProxyPath = sqlite3DbStrDup(0, lockPath);
+  }
+
+  if( rc==SQLITE_OK ){
+    pCtx->dbPath = sqlite3DbStrDup(0, dbPath);
+    if( pCtx->dbPath==NULL ){
+      rc = SQLITE_NOMEM_BKPT;
+    }
+  }
+  if( rc==SQLITE_OK ){
+    /* all memory is allocated, proxys are created and assigned, 
+    ** switch the locking context and pMethod then return.
+    */
+    pCtx->oldLockingContext = pFile->lockingContext;
+    pFile->lockingContext = pCtx;
+    pCtx->pOldMethod = pFile->pMethod;
+    pFile->pMethod = &proxyIoMethods;
+  }else{
+    if( pCtx->conchFile ){ 
+      pCtx->conchFile->pMethod->xClose((sqlite3_file *)pCtx->conchFile);
+      sqlite3_free(pCtx->conchFile);
+    }
+    sqlite3DbFree(0, pCtx->lockProxyPath);
+    sqlite3_free(pCtx->conchFilePath); 
+    sqlite3_free(pCtx);
+  }
+  OSTRACE(("TRANSPROXY  %d %s\n", pFile->h,
+           (rc==SQLITE_OK ? "ok" : "failed")));
+  return rc;
+}
+
+
+/*
+** This routine handles sqlite3_file_control() calls that are specific
+** to proxy locking.
+*/
+static int proxyFileControl(sqlite3_file *id, int op, void *pArg){
+  switch( op ){
+    case SQLITE_FCNTL_GET_LOCKPROXYFILE: {
+      unixFile *pFile = (unixFile*)id;
+      if( pFile->pMethod == &proxyIoMethods ){
+        proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext;
+        proxyTakeConch(pFile);
+        if( pCtx->lockProxyPath ){
+          *(const char **)pArg = pCtx->lockProxyPath;
+        }else{
+          *(const char **)pArg = ":auto: (not held)";
+        }
+      } else {
+        *(const char **)pArg = NULL;
+      }
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_SET_LOCKPROXYFILE: {
+      unixFile *pFile = (unixFile*)id;
+      int rc = SQLITE_OK;
+      int isProxyStyle = (pFile->pMethod == &proxyIoMethods);
+      if( pArg==NULL || (const char *)pArg==0 ){
+        if( isProxyStyle ){
+          /* turn off proxy locking - not supported.  If support is added for
+          ** switching proxy locking mode off then it will need to fail if
+          ** the journal mode is WAL mode. 
+          */
+          rc = SQLITE_ERROR /*SQLITE_PROTOCOL? SQLITE_MISUSE?*/;
+        }else{
+          /* turn off proxy locking - already off - NOOP */
+          rc = SQLITE_OK;
+        }
+      }else{
+        const char *proxyPath = (const char *)pArg;
+        if( isProxyStyle ){
+          proxyLockingContext *pCtx = 
+            (proxyLockingContext*)pFile->lockingContext;
+          if( !strcmp(pArg, ":auto:") 
+           || (pCtx->lockProxyPath &&
+               !strncmp(pCtx->lockProxyPath, proxyPath, MAXPATHLEN))
+          ){
+            rc = SQLITE_OK;
+          }else{
+            rc = switchLockProxyPath(pFile, proxyPath);
+          }
+        }else{
+          /* turn on proxy file locking */
+          rc = proxyTransformUnixFile(pFile, proxyPath);
+        }
+      }
+      return rc;
+    }
+    default: {
+      assert( 0 );  /* The call assures that only valid opcodes are sent */
+    }
+  }
+  /*NOTREACHED*/
+  return SQLITE_ERROR;
+}
+
+/*
+** Within this division (the proxying locking implementation) the procedures
+** above this point are all utilities.  The lock-related methods of the
+** proxy-locking sqlite3_io_method object follow.
+*/
+
+
+/*
+** This routine checks if there is a RESERVED lock held on the specified
+** file by this or any other process. If such a lock is held, set *pResOut
+** to a non-zero value otherwise *pResOut is set to zero.  The return value
+** is set to SQLITE_OK unless an I/O error occurs during lock checking.
+*/
+static int proxyCheckReservedLock(sqlite3_file *id, int *pResOut) {
+  unixFile *pFile = (unixFile*)id;
+  int rc = proxyTakeConch(pFile);
+  if( rc==SQLITE_OK ){
+    proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
+    if( pCtx->conchHeld>0 ){
+      unixFile *proxy = pCtx->lockProxy;
+      return proxy->pMethod->xCheckReservedLock((sqlite3_file*)proxy, pResOut);
+    }else{ /* conchHeld < 0 is lockless */
+      pResOut=0;
+    }
+  }
+  return rc;
+}
+
+/*
+** Lock the file with the lock specified by parameter eFileLock - one
+** of the following:
+**
+**     (1) SHARED_LOCK
+**     (2) RESERVED_LOCK
+**     (3) PENDING_LOCK
+**     (4) EXCLUSIVE_LOCK
+**
+** Sometimes when requesting one lock state, additional lock states
+** are inserted in between.  The locking might fail on one of the later
+** transitions leaving the lock state different from what it started but
+** still short of its goal.  The following chart shows the allowed
+** transitions and the inserted intermediate states:
+**
+**    UNLOCKED -> SHARED
+**    SHARED -> RESERVED
+**    SHARED -> (PENDING) -> EXCLUSIVE
+**    RESERVED -> (PENDING) -> EXCLUSIVE
+**    PENDING -> EXCLUSIVE
+**
+** This routine will only increase a lock.  Use the sqlite3OsUnlock()
+** routine to lower a locking level.
+*/
+static int proxyLock(sqlite3_file *id, int eFileLock) {
+  unixFile *pFile = (unixFile*)id;
+  int rc = proxyTakeConch(pFile);
+  if( rc==SQLITE_OK ){
+    proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
+    if( pCtx->conchHeld>0 ){
+      unixFile *proxy = pCtx->lockProxy;
+      rc = proxy->pMethod->xLock((sqlite3_file*)proxy, eFileLock);
+      pFile->eFileLock = proxy->eFileLock;
+    }else{
+      /* conchHeld < 0 is lockless */
+    }
+  }
+  return rc;
+}
+
+
+/*
+** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+*/
+static int proxyUnlock(sqlite3_file *id, int eFileLock) {
+  unixFile *pFile = (unixFile*)id;
+  int rc = proxyTakeConch(pFile);
+  if( rc==SQLITE_OK ){
+    proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
+    if( pCtx->conchHeld>0 ){
+      unixFile *proxy = pCtx->lockProxy;
+      rc = proxy->pMethod->xUnlock((sqlite3_file*)proxy, eFileLock);
+      pFile->eFileLock = proxy->eFileLock;
+    }else{
+      /* conchHeld < 0 is lockless */
+    }
+  }
+  return rc;
+}
+
+/*
+** Close a file that uses proxy locks.
+*/
+static int proxyClose(sqlite3_file *id) {
+  if( ALWAYS(id) ){
+    unixFile *pFile = (unixFile*)id;
+    proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
+    unixFile *lockProxy = pCtx->lockProxy;
+    unixFile *conchFile = pCtx->conchFile;
+    int rc = SQLITE_OK;
+    
+    if( lockProxy ){
+      rc = lockProxy->pMethod->xUnlock((sqlite3_file*)lockProxy, NO_LOCK);
+      if( rc ) return rc;
+      rc = lockProxy->pMethod->xClose((sqlite3_file*)lockProxy);
+      if( rc ) return rc;
+      sqlite3_free(lockProxy);
+      pCtx->lockProxy = 0;
+    }
+    if( conchFile ){
+      if( pCtx->conchHeld ){
+        rc = proxyReleaseConch(pFile);
+        if( rc ) return rc;
+      }
+      rc = conchFile->pMethod->xClose((sqlite3_file*)conchFile);
+      if( rc ) return rc;
+      sqlite3_free(conchFile);
+    }
+    sqlite3DbFree(0, pCtx->lockProxyPath);
+    sqlite3_free(pCtx->conchFilePath);
+    sqlite3DbFree(0, pCtx->dbPath);
+    /* restore the original locking context and pMethod then close it */
+    pFile->lockingContext = pCtx->oldLockingContext;
+    pFile->pMethod = pCtx->pOldMethod;
+    sqlite3_free(pCtx);
+    return pFile->pMethod->xClose(id);
+  }
+  return SQLITE_OK;
+}
+
+
+
+#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
+/*
+** The proxy locking style is intended for use with AFP filesystems.
+** And since AFP is only supported on MacOSX, the proxy locking is also
+** restricted to MacOSX.
+** 
+**
+******************* End of the proxy lock implementation **********************
+******************************************************************************/
+
+/*
+** Initialize the operating system interface.
+**
+** This routine registers all VFS implementations for unix-like operating
+** systems.  This routine, and the sqlite3_os_end() routine that follows,
+** should be the only routines in this file that are visible from other
+** files.
+**
+** This routine is called once during SQLite initialization and by a
+** single thread.  The memory allocation and mutex subsystems have not
+** necessarily been initialized when this routine is called, and so they
+** should not be used.
+*/
+SQLITE_API int sqlite3_os_init(void){ 
+  /* 
+  ** The following macro defines an initializer for an sqlite3_vfs object.
+  ** The name of the VFS is NAME.  The pAppData is a pointer to a pointer
+  ** to the "finder" function.  (pAppData is a pointer to a pointer because
+  ** silly C90 rules prohibit a void* from being cast to a function pointer
+  ** and so we have to go through the intermediate pointer to avoid problems
+  ** when compiling with -pedantic-errors on GCC.)
+  **
+  ** The FINDER parameter to this macro is the name of the pointer to the
+  ** finder-function.  The finder-function returns a pointer to the
+  ** sqlite_io_methods object that implements the desired locking
+  ** behaviors.  See the division above that contains the IOMETHODS
+  ** macro for addition information on finder-functions.
+  **
+  ** Most finders simply return a pointer to a fixed sqlite3_io_methods
+  ** object.  But the "autolockIoFinder" available on MacOSX does a little
+  ** more than that; it looks at the filesystem type that hosts the 
+  ** database file and tries to choose an locking method appropriate for
+  ** that filesystem time.
+  */
+  #define UNIXVFS(VFSNAME, FINDER) {                        \
+    3,                    /* iVersion */                    \
+    sizeof(unixFile),     /* szOsFile */                    \
+    MAX_PATHNAME,         /* mxPathname */                  \
+    0,                    /* pNext */                       \
+    VFSNAME,              /* zName */                       \
+    (void*)&FINDER,       /* pAppData */                    \
+    unixOpen,             /* xOpen */                       \
+    unixDelete,           /* xDelete */                     \
+    unixAccess,           /* xAccess */                     \
+    unixFullPathname,     /* xFullPathname */               \
+    unixDlOpen,           /* xDlOpen */                     \
+    unixDlError,          /* xDlError */                    \
+    unixDlSym,            /* xDlSym */                      \
+    unixDlClose,          /* xDlClose */                    \
+    unixRandomness,       /* xRandomness */                 \
+    unixSleep,            /* xSleep */                      \
+    unixCurrentTime,      /* xCurrentTime */                \
+    unixGetLastError,     /* xGetLastError */               \
+    unixCurrentTimeInt64, /* xCurrentTimeInt64 */           \
+    unixSetSystemCall,    /* xSetSystemCall */              \
+    unixGetSystemCall,    /* xGetSystemCall */              \
+    unixNextSystemCall,   /* xNextSystemCall */             \
+  }
+
+  /*
+  ** All default VFSes for unix are contained in the following array.
+  **
+  ** Note that the sqlite3_vfs.pNext field of the VFS object is modified
+  ** by the SQLite core when the VFS is registered.  So the following
+  ** array cannot be const.
+  */
+  static sqlite3_vfs aVfs[] = {
+#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
+    UNIXVFS("unix",          autolockIoFinder ),
+#elif OS_VXWORKS
+    UNIXVFS("unix",          vxworksIoFinder ),
+#else
+    UNIXVFS("unix",          posixIoFinder ),
+#endif
+    UNIXVFS("unix-none",     nolockIoFinder ),
+    UNIXVFS("unix-dotfile",  dotlockIoFinder ),
+    UNIXVFS("unix-excl",     posixIoFinder ),
+#if OS_VXWORKS
+    UNIXVFS("unix-namedsem", semIoFinder ),
+#endif
+#if SQLITE_ENABLE_LOCKING_STYLE || OS_VXWORKS
+    UNIXVFS("unix-posix",    posixIoFinder ),
+#endif
+#if SQLITE_ENABLE_LOCKING_STYLE
+    UNIXVFS("unix-flock",    flockIoFinder ),
+#endif
+#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
+    UNIXVFS("unix-afp",      afpIoFinder ),
+    UNIXVFS("unix-nfs",      nfsIoFinder ),
+    UNIXVFS("unix-proxy",    proxyIoFinder ),
+#endif
+  };
+  unsigned int i;          /* Loop counter */
+
+  /* Double-check that the aSyscall[] array has been constructed
+  ** correctly.  See ticket [bb3a86e890c8e96ab] */
+  assert( ArraySize(aSyscall)==28 );
+
+  /* Register all VFSes defined in the aVfs[] array */
+  for(i=0; i<(sizeof(aVfs)/sizeof(sqlite3_vfs)); i++){
+    sqlite3_vfs_register(&aVfs[i], i==0);
+  }
+  return SQLITE_OK; 
+}
+
+/*
+** Shutdown the operating system interface.
+**
+** Some operating systems might need to do some cleanup in this routine,
+** to release dynamically allocated objects.  But not on unix.
+** This routine is a no-op for unix.
+*/
+SQLITE_API int sqlite3_os_end(void){ 
+  return SQLITE_OK; 
+}
+ 
+#endif /* SQLITE_OS_UNIX */
+
+/************** End of os_unix.c *********************************************/
+/************** Begin file os_win.c ******************************************/
+/*
+** 2004 May 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains code that is specific to Windows.
+*/
+/* #include "sqliteInt.h" */
+#if SQLITE_OS_WIN               /* This file is used for Windows only */
+
+/*
+** Include code that is common to all os_*.c files
+*/
+/************** Include os_common.h in the middle of os_win.c ****************/
+/************** Begin file os_common.h ***************************************/
+/*
+** 2004 May 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains macros and a little bit of code that is common to
+** all of the platform-specific files (os_*.c) and is #included into those
+** files.
+**
+** This file should be #included by the os_*.c files only.  It is not a
+** general purpose header file.
+*/
+#ifndef _OS_COMMON_H_
+#define _OS_COMMON_H_
+
+/*
+** At least two bugs have slipped in because we changed the MEMORY_DEBUG
+** macro to SQLITE_DEBUG and some older makefiles have not yet made the
+** switch.  The following code should catch this problem at compile-time.
+*/
+#ifdef MEMORY_DEBUG
+# error "The MEMORY_DEBUG macro is obsolete.  Use SQLITE_DEBUG instead."
+#endif
+
+/*
+** Macros for performance tracing.  Normally turned off.  Only works
+** on i486 hardware.
+*/
+#ifdef SQLITE_PERFORMANCE_TRACE
+
+/*
+** hwtime.h contains inline assembler code for implementing
+** high-performance timing routines.
+*/
+/************** Include hwtime.h in the middle of os_common.h ****************/
+/************** Begin file hwtime.h ******************************************/
+/*
+** 2008 May 27
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains inline asm code for retrieving "high-performance"
+** counters for x86 class CPUs.
+*/
+#ifndef SQLITE_HWTIME_H
+#define SQLITE_HWTIME_H
+
+/*
+** The following routine only works on pentium-class (or newer) processors.
+** It uses the RDTSC opcode to read the cycle count value out of the
+** processor and returns that value.  This can be used for high-res
+** profiling.
+*/
+#if (defined(__GNUC__) || defined(_MSC_VER)) && \
+      (defined(i386) || defined(__i386__) || defined(_M_IX86))
+
+  #if defined(__GNUC__)
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+     unsigned int lo, hi;
+     __asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
+     return (sqlite_uint64)hi << 32 | lo;
+  }
+
+  #elif defined(_MSC_VER)
+
+  __declspec(naked) __inline sqlite_uint64 __cdecl sqlite3Hwtime(void){
+     __asm {
+        rdtsc
+        ret       ; return value at EDX:EAX
+     }
+  }
+
+  #endif
+
+#elif (defined(__GNUC__) && defined(__x86_64__))
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+      unsigned long val;
+      __asm__ __volatile__ ("rdtsc" : "=A" (val));
+      return val;
+  }
+ 
+#elif (defined(__GNUC__) && defined(__ppc__))
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+      unsigned long long retval;
+      unsigned long junk;
+      __asm__ __volatile__ ("\n\
+          1:      mftbu   %1\n\
+                  mftb    %L0\n\
+                  mftbu   %0\n\
+                  cmpw    %0,%1\n\
+                  bne     1b"
+                  : "=r" (retval), "=r" (junk));
+      return retval;
+  }
+
+#else
+
+  #error Need implementation of sqlite3Hwtime() for your platform.
+
+  /*
+  ** To compile without implementing sqlite3Hwtime() for your platform,
+  ** you can remove the above #error and use the following
+  ** stub function.  You will lose timing support for many
+  ** of the debugging and testing utilities, but it should at
+  ** least compile and run.
+  */
+SQLITE_PRIVATE   sqlite_uint64 sqlite3Hwtime(void){ return ((sqlite_uint64)0); }
+
+#endif
+
+#endif /* !defined(SQLITE_HWTIME_H) */
+
+/************** End of hwtime.h **********************************************/
+/************** Continuing where we left off in os_common.h ******************/
+
+static sqlite_uint64 g_start;
+static sqlite_uint64 g_elapsed;
+#define TIMER_START       g_start=sqlite3Hwtime()
+#define TIMER_END         g_elapsed=sqlite3Hwtime()-g_start
+#define TIMER_ELAPSED     g_elapsed
+#else
+#define TIMER_START
+#define TIMER_END
+#define TIMER_ELAPSED     ((sqlite_uint64)0)
+#endif
+
+/*
+** If we compile with the SQLITE_TEST macro set, then the following block
+** of code will give us the ability to simulate a disk I/O error.  This
+** is used for testing the I/O recovery logic.
+*/
+#if defined(SQLITE_TEST)
+SQLITE_API extern int sqlite3_io_error_hit;
+SQLITE_API extern int sqlite3_io_error_hardhit;
+SQLITE_API extern int sqlite3_io_error_pending;
+SQLITE_API extern int sqlite3_io_error_persist;
+SQLITE_API extern int sqlite3_io_error_benign;
+SQLITE_API extern int sqlite3_diskfull_pending;
+SQLITE_API extern int sqlite3_diskfull;
+#define SimulateIOErrorBenign(X) sqlite3_io_error_benign=(X)
+#define SimulateIOError(CODE)  \
+  if( (sqlite3_io_error_persist && sqlite3_io_error_hit) \
+       || sqlite3_io_error_pending-- == 1 )  \
+              { local_ioerr(); CODE; }
+static void local_ioerr(){
+  IOTRACE(("IOERR\n"));
+  sqlite3_io_error_hit++;
+  if( !sqlite3_io_error_benign ) sqlite3_io_error_hardhit++;
+}
+#define SimulateDiskfullError(CODE) \
+   if( sqlite3_diskfull_pending ){ \
+     if( sqlite3_diskfull_pending == 1 ){ \
+       local_ioerr(); \
+       sqlite3_diskfull = 1; \
+       sqlite3_io_error_hit = 1; \
+       CODE; \
+     }else{ \
+       sqlite3_diskfull_pending--; \
+     } \
+   }
+#else
+#define SimulateIOErrorBenign(X)
+#define SimulateIOError(A)
+#define SimulateDiskfullError(A)
+#endif /* defined(SQLITE_TEST) */
+
+/*
+** When testing, keep a count of the number of open files.
+*/
+#if defined(SQLITE_TEST)
+SQLITE_API extern int sqlite3_open_file_count;
+#define OpenCounter(X)  sqlite3_open_file_count+=(X)
+#else
+#define OpenCounter(X)
+#endif /* defined(SQLITE_TEST) */
+
+#endif /* !defined(_OS_COMMON_H_) */
+
+/************** End of os_common.h *******************************************/
+/************** Continuing where we left off in os_win.c *********************/
+
+/*
+** Include the header file for the Windows VFS.
+*/
+/* #include "os_win.h" */
+
+/*
+** Compiling and using WAL mode requires several APIs that are only
+** available in Windows platforms based on the NT kernel.
+*/
+#if !SQLITE_OS_WINNT && !defined(SQLITE_OMIT_WAL)
+#  error "WAL mode requires support from the Windows NT kernel, compile\
+ with SQLITE_OMIT_WAL."
+#endif
+
+#if !SQLITE_OS_WINNT && SQLITE_MAX_MMAP_SIZE>0
+#  error "Memory mapped files require support from the Windows NT kernel,\
+ compile with SQLITE_MAX_MMAP_SIZE=0."
+#endif
+
+/*
+** Are most of the Win32 ANSI APIs available (i.e. with certain exceptions
+** based on the sub-platform)?
+*/
+#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT && !defined(SQLITE_WIN32_NO_ANSI)
+#  define SQLITE_WIN32_HAS_ANSI
+#endif
+
+/*
+** Are most of the Win32 Unicode APIs available (i.e. with certain exceptions
+** based on the sub-platform)?
+*/
+#if (SQLITE_OS_WINCE || SQLITE_OS_WINNT || SQLITE_OS_WINRT) && \
+    !defined(SQLITE_WIN32_NO_WIDE)
+#  define SQLITE_WIN32_HAS_WIDE
+#endif
+
+/*
+** Make sure at least one set of Win32 APIs is available.
+*/
+#if !defined(SQLITE_WIN32_HAS_ANSI) && !defined(SQLITE_WIN32_HAS_WIDE)
+#  error "At least one of SQLITE_WIN32_HAS_ANSI and SQLITE_WIN32_HAS_WIDE\
+ must be defined."
+#endif
+
+/*
+** Define the required Windows SDK version constants if they are not
+** already available.
+*/
+#ifndef NTDDI_WIN8
+#  define NTDDI_WIN8                        0x06020000
+#endif
+
+#ifndef NTDDI_WINBLUE
+#  define NTDDI_WINBLUE                     0x06030000
+#endif
+
+#ifndef NTDDI_WINTHRESHOLD
+#  define NTDDI_WINTHRESHOLD                0x06040000
+#endif
+
+/*
+** Check to see if the GetVersionEx[AW] functions are deprecated on the
+** target system.  GetVersionEx was first deprecated in Win8.1.
+*/
+#ifndef SQLITE_WIN32_GETVERSIONEX
+#  if defined(NTDDI_VERSION) && NTDDI_VERSION >= NTDDI_WINBLUE
+#    define SQLITE_WIN32_GETVERSIONEX   0   /* GetVersionEx() is deprecated */
+#  else
+#    define SQLITE_WIN32_GETVERSIONEX   1   /* GetVersionEx() is current */
+#  endif
+#endif
+
+/*
+** Check to see if the CreateFileMappingA function is supported on the
+** target system.  It is unavailable when using "mincore.lib" on Win10.
+** When compiling for Windows 10, always assume "mincore.lib" is in use.
+*/
+#ifndef SQLITE_WIN32_CREATEFILEMAPPINGA
+#  if defined(NTDDI_VERSION) && NTDDI_VERSION >= NTDDI_WINTHRESHOLD
+#    define SQLITE_WIN32_CREATEFILEMAPPINGA   0
+#  else
+#    define SQLITE_WIN32_CREATEFILEMAPPINGA   1
+#  endif
+#endif
+
+/*
+** This constant should already be defined (in the "WinDef.h" SDK file).
+*/
+#ifndef MAX_PATH
+#  define MAX_PATH                      (260)
+#endif
+
+/*
+** Maximum pathname length (in chars) for Win32.  This should normally be
+** MAX_PATH.
+*/
+#ifndef SQLITE_WIN32_MAX_PATH_CHARS
+#  define SQLITE_WIN32_MAX_PATH_CHARS   (MAX_PATH)
+#endif
+
+/*
+** This constant should already be defined (in the "WinNT.h" SDK file).
+*/
+#ifndef UNICODE_STRING_MAX_CHARS
+#  define UNICODE_STRING_MAX_CHARS      (32767)
+#endif
+
+/*
+** Maximum pathname length (in chars) for WinNT.  This should normally be
+** UNICODE_STRING_MAX_CHARS.
+*/
+#ifndef SQLITE_WINNT_MAX_PATH_CHARS
+#  define SQLITE_WINNT_MAX_PATH_CHARS   (UNICODE_STRING_MAX_CHARS)
+#endif
+
+/*
+** Maximum pathname length (in bytes) for Win32.  The MAX_PATH macro is in
+** characters, so we allocate 4 bytes per character assuming worst-case of
+** 4-bytes-per-character for UTF8.
+*/
+#ifndef SQLITE_WIN32_MAX_PATH_BYTES
+#  define SQLITE_WIN32_MAX_PATH_BYTES   (SQLITE_WIN32_MAX_PATH_CHARS*4)
+#endif
+
+/*
+** Maximum pathname length (in bytes) for WinNT.  This should normally be
+** UNICODE_STRING_MAX_CHARS * sizeof(WCHAR).
+*/
+#ifndef SQLITE_WINNT_MAX_PATH_BYTES
+#  define SQLITE_WINNT_MAX_PATH_BYTES   \
+                            (sizeof(WCHAR) * SQLITE_WINNT_MAX_PATH_CHARS)
+#endif
+
+/*
+** Maximum error message length (in chars) for WinRT.
+*/
+#ifndef SQLITE_WIN32_MAX_ERRMSG_CHARS
+#  define SQLITE_WIN32_MAX_ERRMSG_CHARS (1024)
+#endif
+
+/*
+** Returns non-zero if the character should be treated as a directory
+** separator.
+*/
+#ifndef winIsDirSep
+#  define winIsDirSep(a)                (((a) == '/') || ((a) == '\\'))
+#endif
+
+/*
+** This macro is used when a local variable is set to a value that is
+** [sometimes] not used by the code (e.g. via conditional compilation).
+*/
+#ifndef UNUSED_VARIABLE_VALUE
+#  define UNUSED_VARIABLE_VALUE(x)      (void)(x)
+#endif
+
+/*
+** Returns the character that should be used as the directory separator.
+*/
+#ifndef winGetDirSep
+#  define winGetDirSep()                '\\'
+#endif
+
+/*
+** Do we need to manually define the Win32 file mapping APIs for use with WAL
+** mode or memory mapped files (e.g. these APIs are available in the Windows
+** CE SDK; however, they are not present in the header file)?
+*/
+#if SQLITE_WIN32_FILEMAPPING_API && \
+        (!defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0)
+/*
+** Two of the file mapping APIs are different under WinRT.  Figure out which
+** set we need.
+*/
+#if SQLITE_OS_WINRT
+WINBASEAPI HANDLE WINAPI CreateFileMappingFromApp(HANDLE, \
+        LPSECURITY_ATTRIBUTES, ULONG, ULONG64, LPCWSTR);
+
+WINBASEAPI LPVOID WINAPI MapViewOfFileFromApp(HANDLE, ULONG, ULONG64, SIZE_T);
+#else
+#if defined(SQLITE_WIN32_HAS_ANSI)
+WINBASEAPI HANDLE WINAPI CreateFileMappingA(HANDLE, LPSECURITY_ATTRIBUTES, \
+        DWORD, DWORD, DWORD, LPCSTR);
+#endif /* defined(SQLITE_WIN32_HAS_ANSI) */
+
+#if defined(SQLITE_WIN32_HAS_WIDE)
+WINBASEAPI HANDLE WINAPI CreateFileMappingW(HANDLE, LPSECURITY_ATTRIBUTES, \
+        DWORD, DWORD, DWORD, LPCWSTR);
+#endif /* defined(SQLITE_WIN32_HAS_WIDE) */
+
+WINBASEAPI LPVOID WINAPI MapViewOfFile(HANDLE, DWORD, DWORD, DWORD, SIZE_T);
+#endif /* SQLITE_OS_WINRT */
+
+/*
+** These file mapping APIs are common to both Win32 and WinRT.
+*/
+
+WINBASEAPI BOOL WINAPI FlushViewOfFile(LPCVOID, SIZE_T);
+WINBASEAPI BOOL WINAPI UnmapViewOfFile(LPCVOID);
+#endif /* SQLITE_WIN32_FILEMAPPING_API */
+
+/*
+** Some Microsoft compilers lack this definition.
+*/
+#ifndef INVALID_FILE_ATTRIBUTES
+# define INVALID_FILE_ATTRIBUTES ((DWORD)-1)
+#endif
+
+#ifndef FILE_FLAG_MASK
+# define FILE_FLAG_MASK          (0xFF3C0000)
+#endif
+
+#ifndef FILE_ATTRIBUTE_MASK
+# define FILE_ATTRIBUTE_MASK     (0x0003FFF7)
+#endif
+
+#ifndef SQLITE_OMIT_WAL
+/* Forward references to structures used for WAL */
+typedef struct winShm winShm;           /* A connection to shared-memory */
+typedef struct winShmNode winShmNode;   /* A region of shared-memory */
+#endif
+
+/*
+** WinCE lacks native support for file locking so we have to fake it
+** with some code of our own.
+*/
+#if SQLITE_OS_WINCE
+typedef struct winceLock {
+  int nReaders;       /* Number of reader locks obtained */
+  BOOL bPending;      /* Indicates a pending lock has been obtained */
+  BOOL bReserved;     /* Indicates a reserved lock has been obtained */
+  BOOL bExclusive;    /* Indicates an exclusive lock has been obtained */
+} winceLock;
+#endif
+
+/*
+** The winFile structure is a subclass of sqlite3_file* specific to the win32
+** portability layer.
+*/
+typedef struct winFile winFile;
+struct winFile {
+  const sqlite3_io_methods *pMethod; /*** Must be first ***/
+  sqlite3_vfs *pVfs;      /* The VFS used to open this file */
+  HANDLE h;               /* Handle for accessing the file */
+  u8 locktype;            /* Type of lock currently held on this file */
+  short sharedLockByte;   /* Randomly chosen byte used as a shared lock */
+  u8 ctrlFlags;           /* Flags.  See WINFILE_* below */
+  DWORD lastErrno;        /* The Windows errno from the last I/O error */
+#ifndef SQLITE_OMIT_WAL
+  winShm *pShm;           /* Instance of shared memory on this file */
+#endif
+  const char *zPath;      /* Full pathname of this file */
+  int szChunk;            /* Chunk size configured by FCNTL_CHUNK_SIZE */
+#if SQLITE_OS_WINCE
+  LPWSTR zDeleteOnClose;  /* Name of file to delete when closing */
+  HANDLE hMutex;          /* Mutex used to control access to shared lock */
+  HANDLE hShared;         /* Shared memory segment used for locking */
+  winceLock local;        /* Locks obtained by this instance of winFile */
+  winceLock *shared;      /* Global shared lock memory for the file  */
+#endif
+#if SQLITE_MAX_MMAP_SIZE>0
+  int nFetchOut;                /* Number of outstanding xFetch references */
+  HANDLE hMap;                  /* Handle for accessing memory mapping */
+  void *pMapRegion;             /* Area memory mapped */
+  sqlite3_int64 mmapSize;       /* Usable size of mapped region */
+  sqlite3_int64 mmapSizeActual; /* Actual size of mapped region */
+  sqlite3_int64 mmapSizeMax;    /* Configured FCNTL_MMAP_SIZE value */
+#endif
+};
+
+/*
+** The winVfsAppData structure is used for the pAppData member for all of the
+** Win32 VFS variants.
+*/
+typedef struct winVfsAppData winVfsAppData;
+struct winVfsAppData {
+  const sqlite3_io_methods *pMethod; /* The file I/O methods to use. */
+  void *pAppData;                    /* The extra pAppData, if any. */
+  BOOL bNoLock;                      /* Non-zero if locking is disabled. */
+};
+
+/*
+** Allowed values for winFile.ctrlFlags
+*/
+#define WINFILE_RDONLY          0x02   /* Connection is read only */
+#define WINFILE_PERSIST_WAL     0x04   /* Persistent WAL mode */
+#define WINFILE_PSOW            0x10   /* SQLITE_IOCAP_POWERSAFE_OVERWRITE */
+
+/*
+ * The size of the buffer used by sqlite3_win32_write_debug().
+ */
+#ifndef SQLITE_WIN32_DBG_BUF_SIZE
+#  define SQLITE_WIN32_DBG_BUF_SIZE   ((int)(4096-sizeof(DWORD)))
+#endif
+
+/*
+ * The value used with sqlite3_win32_set_directory() to specify that
+ * the data directory should be changed.
+ */
+#ifndef SQLITE_WIN32_DATA_DIRECTORY_TYPE
+#  define SQLITE_WIN32_DATA_DIRECTORY_TYPE (1)
+#endif
+
+/*
+ * The value used with sqlite3_win32_set_directory() to specify that
+ * the temporary directory should be changed.
+ */
+#ifndef SQLITE_WIN32_TEMP_DIRECTORY_TYPE
+#  define SQLITE_WIN32_TEMP_DIRECTORY_TYPE (2)
+#endif
+
+/*
+ * If compiled with SQLITE_WIN32_MALLOC on Windows, we will use the
+ * various Win32 API heap functions instead of our own.
+ */
+#ifdef SQLITE_WIN32_MALLOC
+
+/*
+ * If this is non-zero, an isolated heap will be created by the native Win32
+ * allocator subsystem; otherwise, the default process heap will be used.  This
+ * setting has no effect when compiling for WinRT.  By default, this is enabled
+ * and an isolated heap will be created to store all allocated data.
+ *
+ ******************************************************************************
+ * WARNING: It is important to note that when this setting is non-zero and the
+ *          winMemShutdown function is called (e.g. by the sqlite3_shutdown
+ *          function), all data that was allocated using the isolated heap will
+ *          be freed immediately and any attempt to access any of that freed
+ *          data will almost certainly result in an immediate access violation.
+ ******************************************************************************
+ */
+#ifndef SQLITE_WIN32_HEAP_CREATE
+#  define SQLITE_WIN32_HEAP_CREATE    (TRUE)
+#endif
+
+/*
+ * This is cache size used in the calculation of the initial size of the
+ * Win32-specific heap.  It cannot be negative.
+ */
+#ifndef SQLITE_WIN32_CACHE_SIZE
+#  if SQLITE_DEFAULT_CACHE_SIZE>=0
+#    define SQLITE_WIN32_CACHE_SIZE (SQLITE_DEFAULT_CACHE_SIZE)
+#  else
+#    define SQLITE_WIN32_CACHE_SIZE (-(SQLITE_DEFAULT_CACHE_SIZE))
+#  endif
+#endif
+
+/*
+ * The initial size of the Win32-specific heap.  This value may be zero.
+ */
+#ifndef SQLITE_WIN32_HEAP_INIT_SIZE
+#  define SQLITE_WIN32_HEAP_INIT_SIZE ((SQLITE_WIN32_CACHE_SIZE) * \
+                                       (SQLITE_DEFAULT_PAGE_SIZE) + 4194304)
+#endif
+
+/*
+ * The maximum size of the Win32-specific heap.  This value may be zero.
+ */
+#ifndef SQLITE_WIN32_HEAP_MAX_SIZE
+#  define SQLITE_WIN32_HEAP_MAX_SIZE  (0)
+#endif
+
+/*
+ * The extra flags to use in calls to the Win32 heap APIs.  This value may be
+ * zero for the default behavior.
+ */
+#ifndef SQLITE_WIN32_HEAP_FLAGS
+#  define SQLITE_WIN32_HEAP_FLAGS     (0)
+#endif
+
+
+/*
+** The winMemData structure stores information required by the Win32-specific
+** sqlite3_mem_methods implementation.
+*/
+typedef struct winMemData winMemData;
+struct winMemData {
+#ifndef NDEBUG
+  u32 magic1;   /* Magic number to detect structure corruption. */
+#endif
+  HANDLE hHeap; /* The handle to our heap. */
+  BOOL bOwned;  /* Do we own the heap (i.e. destroy it on shutdown)? */
+#ifndef NDEBUG
+  u32 magic2;   /* Magic number to detect structure corruption. */
+#endif
+};
+
+#ifndef NDEBUG
+#define WINMEM_MAGIC1     0x42b2830b
+#define WINMEM_MAGIC2     0xbd4d7cf4
+#endif
+
+static struct winMemData win_mem_data = {
+#ifndef NDEBUG
+  WINMEM_MAGIC1,
+#endif
+  NULL, FALSE
+#ifndef NDEBUG
+  ,WINMEM_MAGIC2
+#endif
+};
+
+#ifndef NDEBUG
+#define winMemAssertMagic1() assert( win_mem_data.magic1==WINMEM_MAGIC1 )
+#define winMemAssertMagic2() assert( win_mem_data.magic2==WINMEM_MAGIC2 )
+#define winMemAssertMagic()  winMemAssertMagic1(); winMemAssertMagic2();
+#else
+#define winMemAssertMagic()
+#endif
+
+#define winMemGetDataPtr()  &win_mem_data
+#define winMemGetHeap()     win_mem_data.hHeap
+#define winMemGetOwned()    win_mem_data.bOwned
+
+static void *winMemMalloc(int nBytes);
+static void winMemFree(void *pPrior);
+static void *winMemRealloc(void *pPrior, int nBytes);
+static int winMemSize(void *p);
+static int winMemRoundup(int n);
+static int winMemInit(void *pAppData);
+static void winMemShutdown(void *pAppData);
+
+SQLITE_PRIVATE const sqlite3_mem_methods *sqlite3MemGetWin32(void);
+#endif /* SQLITE_WIN32_MALLOC */
+
+/*
+** The following variable is (normally) set once and never changes
+** thereafter.  It records whether the operating system is Win9x
+** or WinNT.
+**
+** 0:   Operating system unknown.
+** 1:   Operating system is Win9x.
+** 2:   Operating system is WinNT.
+**
+** In order to facilitate testing on a WinNT system, the test fixture
+** can manually set this value to 1 to emulate Win98 behavior.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API LONG SQLITE_WIN32_VOLATILE sqlite3_os_type = 0;
+#else
+static LONG SQLITE_WIN32_VOLATILE sqlite3_os_type = 0;
+#endif
+
+#ifndef SYSCALL
+#  define SYSCALL sqlite3_syscall_ptr
+#endif
+
+/*
+** This function is not available on Windows CE or WinRT.
+ */
+
+#if SQLITE_OS_WINCE || SQLITE_OS_WINRT
+#  define osAreFileApisANSI()       1
+#endif
+
+/*
+** Many system calls are accessed through pointer-to-functions so that
+** they may be overridden at runtime to facilitate fault injection during
+** testing and sandboxing.  The following array holds the names and pointers
+** to all overrideable system calls.
+*/
+static struct win_syscall {
+  const char *zName;            /* Name of the system call */
+  sqlite3_syscall_ptr pCurrent; /* Current value of the system call */
+  sqlite3_syscall_ptr pDefault; /* Default value */
+} aSyscall[] = {
+#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT
+  { "AreFileApisANSI",         (SYSCALL)AreFileApisANSI,         0 },
+#else
+  { "AreFileApisANSI",         (SYSCALL)0,                       0 },
+#endif
+
+#ifndef osAreFileApisANSI
+#define osAreFileApisANSI ((BOOL(WINAPI*)(VOID))aSyscall[0].pCurrent)
+#endif
+
+#if SQLITE_OS_WINCE && defined(SQLITE_WIN32_HAS_WIDE)
+  { "CharLowerW",              (SYSCALL)CharLowerW,              0 },
+#else
+  { "CharLowerW",              (SYSCALL)0,                       0 },
+#endif
+
+#define osCharLowerW ((LPWSTR(WINAPI*)(LPWSTR))aSyscall[1].pCurrent)
+
+#if SQLITE_OS_WINCE && defined(SQLITE_WIN32_HAS_WIDE)
+  { "CharUpperW",              (SYSCALL)CharUpperW,              0 },
+#else
+  { "CharUpperW",              (SYSCALL)0,                       0 },
+#endif
+
+#define osCharUpperW ((LPWSTR(WINAPI*)(LPWSTR))aSyscall[2].pCurrent)
+
+  { "CloseHandle",             (SYSCALL)CloseHandle,             0 },
+
+#define osCloseHandle ((BOOL(WINAPI*)(HANDLE))aSyscall[3].pCurrent)
+
+#if defined(SQLITE_WIN32_HAS_ANSI)
+  { "CreateFileA",             (SYSCALL)CreateFileA,             0 },
+#else
+  { "CreateFileA",             (SYSCALL)0,                       0 },
+#endif
+
+#define osCreateFileA ((HANDLE(WINAPI*)(LPCSTR,DWORD,DWORD, \
+        LPSECURITY_ATTRIBUTES,DWORD,DWORD,HANDLE))aSyscall[4].pCurrent)
+
+#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_HAS_WIDE)
+  { "CreateFileW",             (SYSCALL)CreateFileW,             0 },
+#else
+  { "CreateFileW",             (SYSCALL)0,                       0 },
+#endif
+
+#define osCreateFileW ((HANDLE(WINAPI*)(LPCWSTR,DWORD,DWORD, \
+        LPSECURITY_ATTRIBUTES,DWORD,DWORD,HANDLE))aSyscall[5].pCurrent)
+
+#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_HAS_ANSI) && \
+        (!defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0) && \
+        SQLITE_WIN32_CREATEFILEMAPPINGA
+  { "CreateFileMappingA",      (SYSCALL)CreateFileMappingA,      0 },
+#else
+  { "CreateFileMappingA",      (SYSCALL)0,                       0 },
+#endif
+
+#define osCreateFileMappingA ((HANDLE(WINAPI*)(HANDLE,LPSECURITY_ATTRIBUTES, \
+        DWORD,DWORD,DWORD,LPCSTR))aSyscall[6].pCurrent)
+
+#if SQLITE_OS_WINCE || (!SQLITE_OS_WINRT && defined(SQLITE_WIN32_HAS_WIDE) && \
+        (!defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0))
+  { "CreateFileMappingW",      (SYSCALL)CreateFileMappingW,      0 },
+#else
+  { "CreateFileMappingW",      (SYSCALL)0,                       0 },
+#endif
+
+#define osCreateFileMappingW ((HANDLE(WINAPI*)(HANDLE,LPSECURITY_ATTRIBUTES, \
+        DWORD,DWORD,DWORD,LPCWSTR))aSyscall[7].pCurrent)
+
+#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_HAS_WIDE)
+  { "CreateMutexW",            (SYSCALL)CreateMutexW,            0 },
+#else
+  { "CreateMutexW",            (SYSCALL)0,                       0 },
+#endif
+
+#define osCreateMutexW ((HANDLE(WINAPI*)(LPSECURITY_ATTRIBUTES,BOOL, \
+        LPCWSTR))aSyscall[8].pCurrent)
+
+#if defined(SQLITE_WIN32_HAS_ANSI)
+  { "DeleteFileA",             (SYSCALL)DeleteFileA,             0 },
+#else
+  { "DeleteFileA",             (SYSCALL)0,                       0 },
+#endif
+
+#define osDeleteFileA ((BOOL(WINAPI*)(LPCSTR))aSyscall[9].pCurrent)
+
+#if defined(SQLITE_WIN32_HAS_WIDE)
+  { "DeleteFileW",             (SYSCALL)DeleteFileW,             0 },
+#else
+  { "DeleteFileW",             (SYSCALL)0,                       0 },
+#endif
+
+#define osDeleteFileW ((BOOL(WINAPI*)(LPCWSTR))aSyscall[10].pCurrent)
+
+#if SQLITE_OS_WINCE
+  { "FileTimeToLocalFileTime", (SYSCALL)FileTimeToLocalFileTime, 0 },
+#else
+  { "FileTimeToLocalFileTime", (SYSCALL)0,                       0 },
+#endif
+
+#define osFileTimeToLocalFileTime ((BOOL(WINAPI*)(CONST FILETIME*, \
+        LPFILETIME))aSyscall[11].pCurrent)
+
+#if SQLITE_OS_WINCE
+  { "FileTimeToSystemTime",    (SYSCALL)FileTimeToSystemTime,    0 },
+#else
+  { "FileTimeToSystemTime",    (SYSCALL)0,                       0 },
+#endif
+
+#define osFileTimeToSystemTime ((BOOL(WINAPI*)(CONST FILETIME*, \
+        LPSYSTEMTIME))aSyscall[12].pCurrent)
+
+  { "FlushFileBuffers",        (SYSCALL)FlushFileBuffers,        0 },
+
+#define osFlushFileBuffers ((BOOL(WINAPI*)(HANDLE))aSyscall[13].pCurrent)
+
+#if defined(SQLITE_WIN32_HAS_ANSI)
+  { "FormatMessageA",          (SYSCALL)FormatMessageA,          0 },
+#else
+  { "FormatMessageA",          (SYSCALL)0,                       0 },
+#endif
+
+#define osFormatMessageA ((DWORD(WINAPI*)(DWORD,LPCVOID,DWORD,DWORD,LPSTR, \
+        DWORD,va_list*))aSyscall[14].pCurrent)
+
+#if defined(SQLITE_WIN32_HAS_WIDE)
+  { "FormatMessageW",          (SYSCALL)FormatMessageW,          0 },
+#else
+  { "FormatMessageW",          (SYSCALL)0,                       0 },
+#endif
+
+#define osFormatMessageW ((DWORD(WINAPI*)(DWORD,LPCVOID,DWORD,DWORD,LPWSTR, \
+        DWORD,va_list*))aSyscall[15].pCurrent)
+
+#if !defined(SQLITE_OMIT_LOAD_EXTENSION)
+  { "FreeLibrary",             (SYSCALL)FreeLibrary,             0 },
+#else
+  { "FreeLibrary",             (SYSCALL)0,                       0 },
+#endif
+
+#define osFreeLibrary ((BOOL(WINAPI*)(HMODULE))aSyscall[16].pCurrent)
+
+  { "GetCurrentProcessId",     (SYSCALL)GetCurrentProcessId,     0 },
+
+#define osGetCurrentProcessId ((DWORD(WINAPI*)(VOID))aSyscall[17].pCurrent)
+
+#if !SQLITE_OS_WINCE && defined(SQLITE_WIN32_HAS_ANSI)
+  { "GetDiskFreeSpaceA",       (SYSCALL)GetDiskFreeSpaceA,       0 },
+#else
+  { "GetDiskFreeSpaceA",       (SYSCALL)0,                       0 },
+#endif
+
+#define osGetDiskFreeSpaceA ((BOOL(WINAPI*)(LPCSTR,LPDWORD,LPDWORD,LPDWORD, \
+        LPDWORD))aSyscall[18].pCurrent)
+
+#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT && defined(SQLITE_WIN32_HAS_WIDE)
+  { "GetDiskFreeSpaceW",       (SYSCALL)GetDiskFreeSpaceW,       0 },
+#else
+  { "GetDiskFreeSpaceW",       (SYSCALL)0,                       0 },
+#endif
+
+#define osGetDiskFreeSpaceW ((BOOL(WINAPI*)(LPCWSTR,LPDWORD,LPDWORD,LPDWORD, \
+        LPDWORD))aSyscall[19].pCurrent)
+
+#if defined(SQLITE_WIN32_HAS_ANSI)
+  { "GetFileAttributesA",      (SYSCALL)GetFileAttributesA,      0 },
+#else
+  { "GetFileAttributesA",      (SYSCALL)0,                       0 },
+#endif
+
+#define osGetFileAttributesA ((DWORD(WINAPI*)(LPCSTR))aSyscall[20].pCurrent)
+
+#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_HAS_WIDE)
+  { "GetFileAttributesW",      (SYSCALL)GetFileAttributesW,      0 },
+#else
+  { "GetFileAttributesW",      (SYSCALL)0,                       0 },
+#endif
+
+#define osGetFileAttributesW ((DWORD(WINAPI*)(LPCWSTR))aSyscall[21].pCurrent)
+
+#if defined(SQLITE_WIN32_HAS_WIDE)
+  { "GetFileAttributesExW",    (SYSCALL)GetFileAttributesExW,    0 },
+#else
+  { "GetFileAttributesExW",    (SYSCALL)0,                       0 },
+#endif
+
+#define osGetFileAttributesExW ((BOOL(WINAPI*)(LPCWSTR,GET_FILEEX_INFO_LEVELS, \
+        LPVOID))aSyscall[22].pCurrent)
+
+#if !SQLITE_OS_WINRT
+  { "GetFileSize",             (SYSCALL)GetFileSize,             0 },
+#else
+  { "GetFileSize",             (SYSCALL)0,                       0 },
+#endif
+
+#define osGetFileSize ((DWORD(WINAPI*)(HANDLE,LPDWORD))aSyscall[23].pCurrent)
+
+#if !SQLITE_OS_WINCE && defined(SQLITE_WIN32_HAS_ANSI)
+  { "GetFullPathNameA",        (SYSCALL)GetFullPathNameA,        0 },
+#else
+  { "GetFullPathNameA",        (SYSCALL)0,                       0 },
+#endif
+
+#define osGetFullPathNameA ((DWORD(WINAPI*)(LPCSTR,DWORD,LPSTR, \
+        LPSTR*))aSyscall[24].pCurrent)
+
+#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT && defined(SQLITE_WIN32_HAS_WIDE)
+  { "GetFullPathNameW",        (SYSCALL)GetFullPathNameW,        0 },
+#else
+  { "GetFullPathNameW",        (SYSCALL)0,                       0 },
+#endif
+
+#define osGetFullPathNameW ((DWORD(WINAPI*)(LPCWSTR,DWORD,LPWSTR, \
+        LPWSTR*))aSyscall[25].pCurrent)
+
+  { "GetLastError",            (SYSCALL)GetLastError,            0 },
+
+#define osGetLastError ((DWORD(WINAPI*)(VOID))aSyscall[26].pCurrent)
+
+#if !defined(SQLITE_OMIT_LOAD_EXTENSION)
+#if SQLITE_OS_WINCE
+  /* The GetProcAddressA() routine is only available on Windows CE. */
+  { "GetProcAddressA",         (SYSCALL)GetProcAddressA,         0 },
+#else
+  /* All other Windows platforms expect GetProcAddress() to take
+  ** an ANSI string regardless of the _UNICODE setting */
+  { "GetProcAddressA",         (SYSCALL)GetProcAddress,          0 },
+#endif
+#else
+  { "GetProcAddressA",         (SYSCALL)0,                       0 },
+#endif
+
+#define osGetProcAddressA ((FARPROC(WINAPI*)(HMODULE, \
+        LPCSTR))aSyscall[27].pCurrent)
+
+#if !SQLITE_OS_WINRT
+  { "GetSystemInfo",           (SYSCALL)GetSystemInfo,           0 },
+#else
+  { "GetSystemInfo",           (SYSCALL)0,                       0 },
+#endif
+
+#define osGetSystemInfo ((VOID(WINAPI*)(LPSYSTEM_INFO))aSyscall[28].pCurrent)
+
+  { "GetSystemTime",           (SYSCALL)GetSystemTime,           0 },
+
+#define osGetSystemTime ((VOID(WINAPI*)(LPSYSTEMTIME))aSyscall[29].pCurrent)
+
+#if !SQLITE_OS_WINCE
+  { "GetSystemTimeAsFileTime", (SYSCALL)GetSystemTimeAsFileTime, 0 },
+#else
+  { "GetSystemTimeAsFileTime", (SYSCALL)0,                       0 },
+#endif
+
+#define osGetSystemTimeAsFileTime ((VOID(WINAPI*)( \
+        LPFILETIME))aSyscall[30].pCurrent)
+
+#if defined(SQLITE_WIN32_HAS_ANSI)
+  { "GetTempPathA",            (SYSCALL)GetTempPathA,            0 },
+#else
+  { "GetTempPathA",            (SYSCALL)0,                       0 },
+#endif
+
+#define osGetTempPathA ((DWORD(WINAPI*)(DWORD,LPSTR))aSyscall[31].pCurrent)
+
+#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_HAS_WIDE)
+  { "GetTempPathW",            (SYSCALL)GetTempPathW,            0 },
+#else
+  { "GetTempPathW",            (SYSCALL)0,                       0 },
+#endif
+
+#define osGetTempPathW ((DWORD(WINAPI*)(DWORD,LPWSTR))aSyscall[32].pCurrent)
+
+#if !SQLITE_OS_WINRT
+  { "GetTickCount",            (SYSCALL)GetTickCount,            0 },
+#else
+  { "GetTickCount",            (SYSCALL)0,                       0 },
+#endif
+
+#define osGetTickCount ((DWORD(WINAPI*)(VOID))aSyscall[33].pCurrent)
+
+#if defined(SQLITE_WIN32_HAS_ANSI) && SQLITE_WIN32_GETVERSIONEX
+  { "GetVersionExA",           (SYSCALL)GetVersionExA,           0 },
+#else
+  { "GetVersionExA",           (SYSCALL)0,                       0 },
+#endif
+
+#define osGetVersionExA ((BOOL(WINAPI*)( \
+        LPOSVERSIONINFOA))aSyscall[34].pCurrent)
+
+#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_HAS_WIDE) && \
+        SQLITE_WIN32_GETVERSIONEX
+  { "GetVersionExW",           (SYSCALL)GetVersionExW,           0 },
+#else
+  { "GetVersionExW",           (SYSCALL)0,                       0 },
+#endif
+
+#define osGetVersionExW ((BOOL(WINAPI*)( \
+        LPOSVERSIONINFOW))aSyscall[35].pCurrent)
+
+  { "HeapAlloc",               (SYSCALL)HeapAlloc,               0 },
+
+#define osHeapAlloc ((LPVOID(WINAPI*)(HANDLE,DWORD, \
+        SIZE_T))aSyscall[36].pCurrent)
+
+#if !SQLITE_OS_WINRT
+  { "HeapCreate",              (SYSCALL)HeapCreate,              0 },
+#else
+  { "HeapCreate",              (SYSCALL)0,                       0 },
+#endif
+
+#define osHeapCreate ((HANDLE(WINAPI*)(DWORD,SIZE_T, \
+        SIZE_T))aSyscall[37].pCurrent)
+
+#if !SQLITE_OS_WINRT
+  { "HeapDestroy",             (SYSCALL)HeapDestroy,             0 },
+#else
+  { "HeapDestroy",             (SYSCALL)0,                       0 },
+#endif
+
+#define osHeapDestroy ((BOOL(WINAPI*)(HANDLE))aSyscall[38].pCurrent)
+
+  { "HeapFree",                (SYSCALL)HeapFree,                0 },
+
+#define osHeapFree ((BOOL(WINAPI*)(HANDLE,DWORD,LPVOID))aSyscall[39].pCurrent)
+
+  { "HeapReAlloc",             (SYSCALL)HeapReAlloc,             0 },
+
+#define osHeapReAlloc ((LPVOID(WINAPI*)(HANDLE,DWORD,LPVOID, \
+        SIZE_T))aSyscall[40].pCurrent)
+
+  { "HeapSize",                (SYSCALL)HeapSize,                0 },
+
+#define osHeapSize ((SIZE_T(WINAPI*)(HANDLE,DWORD, \
+        LPCVOID))aSyscall[41].pCurrent)
+
+#if !SQLITE_OS_WINRT
+  { "HeapValidate",            (SYSCALL)HeapValidate,            0 },
+#else
+  { "HeapValidate",            (SYSCALL)0,                       0 },
+#endif
+
+#define osHeapValidate ((BOOL(WINAPI*)(HANDLE,DWORD, \
+        LPCVOID))aSyscall[42].pCurrent)
+
+#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT
+  { "HeapCompact",             (SYSCALL)HeapCompact,             0 },
+#else
+  { "HeapCompact",             (SYSCALL)0,                       0 },
+#endif
+
+#define osHeapCompact ((UINT(WINAPI*)(HANDLE,DWORD))aSyscall[43].pCurrent)
+
+#if defined(SQLITE_WIN32_HAS_ANSI) && !defined(SQLITE_OMIT_LOAD_EXTENSION)
+  { "LoadLibraryA",            (SYSCALL)LoadLibraryA,            0 },
+#else
+  { "LoadLibraryA",            (SYSCALL)0,                       0 },
+#endif
+
+#define osLoadLibraryA ((HMODULE(WINAPI*)(LPCSTR))aSyscall[44].pCurrent)
+
+#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_HAS_WIDE) && \
+        !defined(SQLITE_OMIT_LOAD_EXTENSION)
+  { "LoadLibraryW",            (SYSCALL)LoadLibraryW,            0 },
+#else
+  { "LoadLibraryW",            (SYSCALL)0,                       0 },
+#endif
+
+#define osLoadLibraryW ((HMODULE(WINAPI*)(LPCWSTR))aSyscall[45].pCurrent)
+
+#if !SQLITE_OS_WINRT
+  { "LocalFree",               (SYSCALL)LocalFree,               0 },
+#else
+  { "LocalFree",               (SYSCALL)0,                       0 },
+#endif
+
+#define osLocalFree ((HLOCAL(WINAPI*)(HLOCAL))aSyscall[46].pCurrent)
+
+#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT
+  { "LockFile",                (SYSCALL)LockFile,                0 },
+#else
+  { "LockFile",                (SYSCALL)0,                       0 },
+#endif
+
+#ifndef osLockFile
+#define osLockFile ((BOOL(WINAPI*)(HANDLE,DWORD,DWORD,DWORD, \
+        DWORD))aSyscall[47].pCurrent)
+#endif
+
+#if !SQLITE_OS_WINCE
+  { "LockFileEx",              (SYSCALL)LockFileEx,              0 },
+#else
+  { "LockFileEx",              (SYSCALL)0,                       0 },
+#endif
+
+#ifndef osLockFileEx
+#define osLockFileEx ((BOOL(WINAPI*)(HANDLE,DWORD,DWORD,DWORD,DWORD, \
+        LPOVERLAPPED))aSyscall[48].pCurrent)
+#endif
+
+#if SQLITE_OS_WINCE || (!SQLITE_OS_WINRT && \
+        (!defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0))
+  { "MapViewOfFile",           (SYSCALL)MapViewOfFile,           0 },
+#else
+  { "MapViewOfFile",           (SYSCALL)0,                       0 },
+#endif
+
+#define osMapViewOfFile ((LPVOID(WINAPI*)(HANDLE,DWORD,DWORD,DWORD, \
+        SIZE_T))aSyscall[49].pCurrent)
+
+  { "MultiByteToWideChar",     (SYSCALL)MultiByteToWideChar,     0 },
+
+#define osMultiByteToWideChar ((int(WINAPI*)(UINT,DWORD,LPCSTR,int,LPWSTR, \
+        int))aSyscall[50].pCurrent)
+
+  { "QueryPerformanceCounter", (SYSCALL)QueryPerformanceCounter, 0 },
+
+#define osQueryPerformanceCounter ((BOOL(WINAPI*)( \
+        LARGE_INTEGER*))aSyscall[51].pCurrent)
+
+  { "ReadFile",                (SYSCALL)ReadFile,                0 },
+
+#define osReadFile ((BOOL(WINAPI*)(HANDLE,LPVOID,DWORD,LPDWORD, \
+        LPOVERLAPPED))aSyscall[52].pCurrent)
+
+  { "SetEndOfFile",            (SYSCALL)SetEndOfFile,            0 },
+
+#define osSetEndOfFile ((BOOL(WINAPI*)(HANDLE))aSyscall[53].pCurrent)
+
+#if !SQLITE_OS_WINRT
+  { "SetFilePointer",          (SYSCALL)SetFilePointer,          0 },
+#else
+  { "SetFilePointer",          (SYSCALL)0,                       0 },
+#endif
+
+#define osSetFilePointer ((DWORD(WINAPI*)(HANDLE,LONG,PLONG, \
+        DWORD))aSyscall[54].pCurrent)
+
+#if !SQLITE_OS_WINRT
+  { "Sleep",                   (SYSCALL)Sleep,                   0 },
+#else
+  { "Sleep",                   (SYSCALL)0,                       0 },
+#endif
+
+#define osSleep ((VOID(WINAPI*)(DWORD))aSyscall[55].pCurrent)
+
+  { "SystemTimeToFileTime",    (SYSCALL)SystemTimeToFileTime,    0 },
+
+#define osSystemTimeToFileTime ((BOOL(WINAPI*)(CONST SYSTEMTIME*, \
+        LPFILETIME))aSyscall[56].pCurrent)
+
+#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT
+  { "UnlockFile",              (SYSCALL)UnlockFile,              0 },
+#else
+  { "UnlockFile",              (SYSCALL)0,                       0 },
+#endif
+
+#ifndef osUnlockFile
+#define osUnlockFile ((BOOL(WINAPI*)(HANDLE,DWORD,DWORD,DWORD, \
+        DWORD))aSyscall[57].pCurrent)
+#endif
+
+#if !SQLITE_OS_WINCE
+  { "UnlockFileEx",            (SYSCALL)UnlockFileEx,            0 },
+#else
+  { "UnlockFileEx",            (SYSCALL)0,                       0 },
+#endif
+
+#define osUnlockFileEx ((BOOL(WINAPI*)(HANDLE,DWORD,DWORD,DWORD, \
+        LPOVERLAPPED))aSyscall[58].pCurrent)
+
+#if SQLITE_OS_WINCE || !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0
+  { "UnmapViewOfFile",         (SYSCALL)UnmapViewOfFile,         0 },
+#else
+  { "UnmapViewOfFile",         (SYSCALL)0,                       0 },
+#endif
+
+#define osUnmapViewOfFile ((BOOL(WINAPI*)(LPCVOID))aSyscall[59].pCurrent)
+
+  { "WideCharToMultiByte",     (SYSCALL)WideCharToMultiByte,     0 },
+
+#define osWideCharToMultiByte ((int(WINAPI*)(UINT,DWORD,LPCWSTR,int,LPSTR,int, \
+        LPCSTR,LPBOOL))aSyscall[60].pCurrent)
+
+  { "WriteFile",               (SYSCALL)WriteFile,               0 },
+
+#define osWriteFile ((BOOL(WINAPI*)(HANDLE,LPCVOID,DWORD,LPDWORD, \
+        LPOVERLAPPED))aSyscall[61].pCurrent)
+
+#if SQLITE_OS_WINRT
+  { "CreateEventExW",          (SYSCALL)CreateEventExW,          0 },
+#else
+  { "CreateEventExW",          (SYSCALL)0,                       0 },
+#endif
+
+#define osCreateEventExW ((HANDLE(WINAPI*)(LPSECURITY_ATTRIBUTES,LPCWSTR, \
+        DWORD,DWORD))aSyscall[62].pCurrent)
+
+#if !SQLITE_OS_WINRT
+  { "WaitForSingleObject",     (SYSCALL)WaitForSingleObject,     0 },
+#else
+  { "WaitForSingleObject",     (SYSCALL)0,                       0 },
+#endif
+
+#define osWaitForSingleObject ((DWORD(WINAPI*)(HANDLE, \
+        DWORD))aSyscall[63].pCurrent)
+
+#if !SQLITE_OS_WINCE
+  { "WaitForSingleObjectEx",   (SYSCALL)WaitForSingleObjectEx,   0 },
+#else
+  { "WaitForSingleObjectEx",   (SYSCALL)0,                       0 },
+#endif
+
+#define osWaitForSingleObjectEx ((DWORD(WINAPI*)(HANDLE,DWORD, \
+        BOOL))aSyscall[64].pCurrent)
+
+#if SQLITE_OS_WINRT
+  { "SetFilePointerEx",        (SYSCALL)SetFilePointerEx,        0 },
+#else
+  { "SetFilePointerEx",        (SYSCALL)0,                       0 },
+#endif
+
+#define osSetFilePointerEx ((BOOL(WINAPI*)(HANDLE,LARGE_INTEGER, \
+        PLARGE_INTEGER,DWORD))aSyscall[65].pCurrent)
+
+#if SQLITE_OS_WINRT
+  { "GetFileInformationByHandleEx", (SYSCALL)GetFileInformationByHandleEx, 0 },
+#else
+  { "GetFileInformationByHandleEx", (SYSCALL)0,                  0 },
+#endif
+
+#define osGetFileInformationByHandleEx ((BOOL(WINAPI*)(HANDLE, \
+        FILE_INFO_BY_HANDLE_CLASS,LPVOID,DWORD))aSyscall[66].pCurrent)
+
+#if SQLITE_OS_WINRT && (!defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0)
+  { "MapViewOfFileFromApp",    (SYSCALL)MapViewOfFileFromApp,    0 },
+#else
+  { "MapViewOfFileFromApp",    (SYSCALL)0,                       0 },
+#endif
+
+#define osMapViewOfFileFromApp ((LPVOID(WINAPI*)(HANDLE,ULONG,ULONG64, \
+        SIZE_T))aSyscall[67].pCurrent)
+
+#if SQLITE_OS_WINRT
+  { "CreateFile2",             (SYSCALL)CreateFile2,             0 },
+#else
+  { "CreateFile2",             (SYSCALL)0,                       0 },
+#endif
+
+#define osCreateFile2 ((HANDLE(WINAPI*)(LPCWSTR,DWORD,DWORD,DWORD, \
+        LPCREATEFILE2_EXTENDED_PARAMETERS))aSyscall[68].pCurrent)
+
+#if SQLITE_OS_WINRT && !defined(SQLITE_OMIT_LOAD_EXTENSION)
+  { "LoadPackagedLibrary",     (SYSCALL)LoadPackagedLibrary,     0 },
+#else
+  { "LoadPackagedLibrary",     (SYSCALL)0,                       0 },
+#endif
+
+#define osLoadPackagedLibrary ((HMODULE(WINAPI*)(LPCWSTR, \
+        DWORD))aSyscall[69].pCurrent)
+
+#if SQLITE_OS_WINRT
+  { "GetTickCount64",          (SYSCALL)GetTickCount64,          0 },
+#else
+  { "GetTickCount64",          (SYSCALL)0,                       0 },
+#endif
+
+#define osGetTickCount64 ((ULONGLONG(WINAPI*)(VOID))aSyscall[70].pCurrent)
+
+#if SQLITE_OS_WINRT
+  { "GetNativeSystemInfo",     (SYSCALL)GetNativeSystemInfo,     0 },
+#else
+  { "GetNativeSystemInfo",     (SYSCALL)0,                       0 },
+#endif
+
+#define osGetNativeSystemInfo ((VOID(WINAPI*)( \
+        LPSYSTEM_INFO))aSyscall[71].pCurrent)
+
+#if defined(SQLITE_WIN32_HAS_ANSI)
+  { "OutputDebugStringA",      (SYSCALL)OutputDebugStringA,      0 },
+#else
+  { "OutputDebugStringA",      (SYSCALL)0,                       0 },
+#endif
+
+#define osOutputDebugStringA ((VOID(WINAPI*)(LPCSTR))aSyscall[72].pCurrent)
+
+#if defined(SQLITE_WIN32_HAS_WIDE)
+  { "OutputDebugStringW",      (SYSCALL)OutputDebugStringW,      0 },
+#else
+  { "OutputDebugStringW",      (SYSCALL)0,                       0 },
+#endif
+
+#define osOutputDebugStringW ((VOID(WINAPI*)(LPCWSTR))aSyscall[73].pCurrent)
+
+  { "GetProcessHeap",          (SYSCALL)GetProcessHeap,          0 },
+
+#define osGetProcessHeap ((HANDLE(WINAPI*)(VOID))aSyscall[74].pCurrent)
+
+#if SQLITE_OS_WINRT && (!defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0)
+  { "CreateFileMappingFromApp", (SYSCALL)CreateFileMappingFromApp, 0 },
+#else
+  { "CreateFileMappingFromApp", (SYSCALL)0,                      0 },
+#endif
+
+#define osCreateFileMappingFromApp ((HANDLE(WINAPI*)(HANDLE, \
+        LPSECURITY_ATTRIBUTES,ULONG,ULONG64,LPCWSTR))aSyscall[75].pCurrent)
+
+/*
+** NOTE: On some sub-platforms, the InterlockedCompareExchange "function"
+**       is really just a macro that uses a compiler intrinsic (e.g. x64).
+**       So do not try to make this is into a redefinable interface.
+*/
+#if defined(InterlockedCompareExchange)
+  { "InterlockedCompareExchange", (SYSCALL)0,                    0 },
+
+#define osInterlockedCompareExchange InterlockedCompareExchange
+#else
+  { "InterlockedCompareExchange", (SYSCALL)InterlockedCompareExchange, 0 },
+
+#define osInterlockedCompareExchange ((LONG(WINAPI*)(LONG \
+        SQLITE_WIN32_VOLATILE*, LONG,LONG))aSyscall[76].pCurrent)
+#endif /* defined(InterlockedCompareExchange) */
+
+#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT && SQLITE_WIN32_USE_UUID
+  { "UuidCreate",               (SYSCALL)UuidCreate,             0 },
+#else
+  { "UuidCreate",               (SYSCALL)0,                      0 },
+#endif
+
+#define osUuidCreate ((RPC_STATUS(RPC_ENTRY*)(UUID*))aSyscall[77].pCurrent)
+
+#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT && SQLITE_WIN32_USE_UUID
+  { "UuidCreateSequential",     (SYSCALL)UuidCreateSequential,   0 },
+#else
+  { "UuidCreateSequential",     (SYSCALL)0,                      0 },
+#endif
+
+#define osUuidCreateSequential \
+        ((RPC_STATUS(RPC_ENTRY*)(UUID*))aSyscall[78].pCurrent)
+
+#if !defined(SQLITE_NO_SYNC) && SQLITE_MAX_MMAP_SIZE>0
+  { "FlushViewOfFile",          (SYSCALL)FlushViewOfFile,        0 },
+#else
+  { "FlushViewOfFile",          (SYSCALL)0,                      0 },
+#endif
+
+#define osFlushViewOfFile \
+        ((BOOL(WINAPI*)(LPCVOID,SIZE_T))aSyscall[79].pCurrent)
+
+}; /* End of the overrideable system calls */
+
+/*
+** This is the xSetSystemCall() method of sqlite3_vfs for all of the
+** "win32" VFSes.  Return SQLITE_OK opon successfully updating the
+** system call pointer, or SQLITE_NOTFOUND if there is no configurable
+** system call named zName.
+*/
+static int winSetSystemCall(
+  sqlite3_vfs *pNotUsed,        /* The VFS pointer.  Not used */
+  const char *zName,            /* Name of system call to override */
+  sqlite3_syscall_ptr pNewFunc  /* Pointer to new system call value */
+){
+  unsigned int i;
+  int rc = SQLITE_NOTFOUND;
+
+  UNUSED_PARAMETER(pNotUsed);
+  if( zName==0 ){
+    /* If no zName is given, restore all system calls to their default
+    ** settings and return NULL
+    */
+    rc = SQLITE_OK;
+    for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
+      if( aSyscall[i].pDefault ){
+        aSyscall[i].pCurrent = aSyscall[i].pDefault;
+      }
+    }
+  }else{
+    /* If zName is specified, operate on only the one system call
+    ** specified.
+    */
+    for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
+      if( strcmp(zName, aSyscall[i].zName)==0 ){
+        if( aSyscall[i].pDefault==0 ){
+          aSyscall[i].pDefault = aSyscall[i].pCurrent;
+        }
+        rc = SQLITE_OK;
+        if( pNewFunc==0 ) pNewFunc = aSyscall[i].pDefault;
+        aSyscall[i].pCurrent = pNewFunc;
+        break;
+      }
+    }
+  }
+  return rc;
+}
+
+/*
+** Return the value of a system call.  Return NULL if zName is not a
+** recognized system call name.  NULL is also returned if the system call
+** is currently undefined.
+*/
+static sqlite3_syscall_ptr winGetSystemCall(
+  sqlite3_vfs *pNotUsed,
+  const char *zName
+){
+  unsigned int i;
+
+  UNUSED_PARAMETER(pNotUsed);
+  for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
+    if( strcmp(zName, aSyscall[i].zName)==0 ) return aSyscall[i].pCurrent;
+  }
+  return 0;
+}
+
+/*
+** Return the name of the first system call after zName.  If zName==NULL
+** then return the name of the first system call.  Return NULL if zName
+** is the last system call or if zName is not the name of a valid
+** system call.
+*/
+static const char *winNextSystemCall(sqlite3_vfs *p, const char *zName){
+  int i = -1;
+
+  UNUSED_PARAMETER(p);
+  if( zName ){
+    for(i=0; i<ArraySize(aSyscall)-1; i++){
+      if( strcmp(zName, aSyscall[i].zName)==0 ) break;
+    }
+  }
+  for(i++; i<ArraySize(aSyscall); i++){
+    if( aSyscall[i].pCurrent!=0 ) return aSyscall[i].zName;
+  }
+  return 0;
+}
+
+#ifdef SQLITE_WIN32_MALLOC
+/*
+** If a Win32 native heap has been configured, this function will attempt to
+** compact it.  Upon success, SQLITE_OK will be returned.  Upon failure, one
+** of SQLITE_NOMEM, SQLITE_ERROR, or SQLITE_NOTFOUND will be returned.  The
+** "pnLargest" argument, if non-zero, will be used to return the size of the
+** largest committed free block in the heap, in bytes.
+*/
+SQLITE_API int sqlite3_win32_compact_heap(LPUINT pnLargest){
+  int rc = SQLITE_OK;
+  UINT nLargest = 0;
+  HANDLE hHeap;
+
+  winMemAssertMagic();
+  hHeap = winMemGetHeap();
+  assert( hHeap!=0 );
+  assert( hHeap!=INVALID_HANDLE_VALUE );
+#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_MALLOC_VALIDATE)
+  assert( osHeapValidate(hHeap, SQLITE_WIN32_HEAP_FLAGS, NULL) );
+#endif
+#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT
+  if( (nLargest=osHeapCompact(hHeap, SQLITE_WIN32_HEAP_FLAGS))==0 ){
+    DWORD lastErrno = osGetLastError();
+    if( lastErrno==NO_ERROR ){
+      sqlite3_log(SQLITE_NOMEM, "failed to HeapCompact (no space), heap=%p",
+                  (void*)hHeap);
+      rc = SQLITE_NOMEM_BKPT;
+    }else{
+      sqlite3_log(SQLITE_ERROR, "failed to HeapCompact (%lu), heap=%p",
+                  osGetLastError(), (void*)hHeap);
+      rc = SQLITE_ERROR;
+    }
+  }
+#else
+  sqlite3_log(SQLITE_NOTFOUND, "failed to HeapCompact, heap=%p",
+              (void*)hHeap);
+  rc = SQLITE_NOTFOUND;
+#endif
+  if( pnLargest ) *pnLargest = nLargest;
+  return rc;
+}
+
+/*
+** If a Win32 native heap has been configured, this function will attempt to
+** destroy and recreate it.  If the Win32 native heap is not isolated and/or
+** the sqlite3_memory_used() function does not return zero, SQLITE_BUSY will
+** be returned and no changes will be made to the Win32 native heap.
+*/
+SQLITE_API int sqlite3_win32_reset_heap(){
+  int rc;
+  MUTEX_LOGIC( sqlite3_mutex *pMaster; ) /* The main static mutex */
+  MUTEX_LOGIC( sqlite3_mutex *pMem; )    /* The memsys static mutex */
+  MUTEX_LOGIC( pMaster = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); )
+  MUTEX_LOGIC( pMem = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM); )
+  sqlite3_mutex_enter(pMaster);
+  sqlite3_mutex_enter(pMem);
+  winMemAssertMagic();
+  if( winMemGetHeap()!=NULL && winMemGetOwned() && sqlite3_memory_used()==0 ){
+    /*
+    ** At this point, there should be no outstanding memory allocations on
+    ** the heap.  Also, since both the master and memsys locks are currently
+    ** being held by us, no other function (i.e. from another thread) should
+    ** be able to even access the heap.  Attempt to destroy and recreate our
+    ** isolated Win32 native heap now.
+    */
+    assert( winMemGetHeap()!=NULL );
+    assert( winMemGetOwned() );
+    assert( sqlite3_memory_used()==0 );
+    winMemShutdown(winMemGetDataPtr());
+    assert( winMemGetHeap()==NULL );
+    assert( !winMemGetOwned() );
+    assert( sqlite3_memory_used()==0 );
+    rc = winMemInit(winMemGetDataPtr());
+    assert( rc!=SQLITE_OK || winMemGetHeap()!=NULL );
+    assert( rc!=SQLITE_OK || winMemGetOwned() );
+    assert( rc!=SQLITE_OK || sqlite3_memory_used()==0 );
+  }else{
+    /*
+    ** The Win32 native heap cannot be modified because it may be in use.
+    */
+    rc = SQLITE_BUSY;
+  }
+  sqlite3_mutex_leave(pMem);
+  sqlite3_mutex_leave(pMaster);
+  return rc;
+}
+#endif /* SQLITE_WIN32_MALLOC */
+
+/*
+** This function outputs the specified (ANSI) string to the Win32 debugger
+** (if available).
+*/
+
+SQLITE_API void sqlite3_win32_write_debug(const char *zBuf, int nBuf){
+  char zDbgBuf[SQLITE_WIN32_DBG_BUF_SIZE];
+  int nMin = MIN(nBuf, (SQLITE_WIN32_DBG_BUF_SIZE - 1)); /* may be negative. */
+  if( nMin<-1 ) nMin = -1; /* all negative values become -1. */
+  assert( nMin==-1 || nMin==0 || nMin<SQLITE_WIN32_DBG_BUF_SIZE );
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !zBuf ){
+    (void)SQLITE_MISUSE_BKPT;
+    return;
+  }
+#endif
+#if defined(SQLITE_WIN32_HAS_ANSI)
+  if( nMin>0 ){
+    memset(zDbgBuf, 0, SQLITE_WIN32_DBG_BUF_SIZE);
+    memcpy(zDbgBuf, zBuf, nMin);
+    osOutputDebugStringA(zDbgBuf);
+  }else{
+    osOutputDebugStringA(zBuf);
+  }
+#elif defined(SQLITE_WIN32_HAS_WIDE)
+  memset(zDbgBuf, 0, SQLITE_WIN32_DBG_BUF_SIZE);
+  if ( osMultiByteToWideChar(
+          osAreFileApisANSI() ? CP_ACP : CP_OEMCP, 0, zBuf,
+          nMin, (LPWSTR)zDbgBuf, SQLITE_WIN32_DBG_BUF_SIZE/sizeof(WCHAR))<=0 ){
+    return;
+  }
+  osOutputDebugStringW((LPCWSTR)zDbgBuf);
+#else
+  if( nMin>0 ){
+    memset(zDbgBuf, 0, SQLITE_WIN32_DBG_BUF_SIZE);
+    memcpy(zDbgBuf, zBuf, nMin);
+    fprintf(stderr, "%s", zDbgBuf);
+  }else{
+    fprintf(stderr, "%s", zBuf);
+  }
+#endif
+}
+
+/*
+** The following routine suspends the current thread for at least ms
+** milliseconds.  This is equivalent to the Win32 Sleep() interface.
+*/
+#if SQLITE_OS_WINRT
+static HANDLE sleepObj = NULL;
+#endif
+
+SQLITE_API void sqlite3_win32_sleep(DWORD milliseconds){
+#if SQLITE_OS_WINRT
+  if ( sleepObj==NULL ){
+    sleepObj = osCreateEventExW(NULL, NULL, CREATE_EVENT_MANUAL_RESET,
+                                SYNCHRONIZE);
+  }
+  assert( sleepObj!=NULL );
+  osWaitForSingleObjectEx(sleepObj, milliseconds, FALSE);
+#else
+  osSleep(milliseconds);
+#endif
+}
+
+#if SQLITE_MAX_WORKER_THREADS>0 && !SQLITE_OS_WINCE && !SQLITE_OS_WINRT && \
+        SQLITE_THREADSAFE>0
+SQLITE_PRIVATE DWORD sqlite3Win32Wait(HANDLE hObject){
+  DWORD rc;
+  while( (rc = osWaitForSingleObjectEx(hObject, INFINITE,
+                                       TRUE))==WAIT_IO_COMPLETION ){}
+  return rc;
+}
+#endif
+
+/*
+** Return true (non-zero) if we are running under WinNT, Win2K, WinXP,
+** or WinCE.  Return false (zero) for Win95, Win98, or WinME.
+**
+** Here is an interesting observation:  Win95, Win98, and WinME lack
+** the LockFileEx() API.  But we can still statically link against that
+** API as long as we don't call it when running Win95/98/ME.  A call to
+** this routine is used to determine if the host is Win95/98/ME or
+** WinNT/2K/XP so that we will know whether or not we can safely call
+** the LockFileEx() API.
+*/
+
+#if !SQLITE_WIN32_GETVERSIONEX
+# define osIsNT()  (1)
+#elif SQLITE_OS_WINCE || SQLITE_OS_WINRT || !defined(SQLITE_WIN32_HAS_ANSI)
+# define osIsNT()  (1)
+#elif !defined(SQLITE_WIN32_HAS_WIDE)
+# define osIsNT()  (0)
+#else
+# define osIsNT()  ((sqlite3_os_type==2) || sqlite3_win32_is_nt())
+#endif
+
+/*
+** This function determines if the machine is running a version of Windows
+** based on the NT kernel.
+*/
+SQLITE_API int sqlite3_win32_is_nt(void){
+#if SQLITE_OS_WINRT
+  /*
+  ** NOTE: The WinRT sub-platform is always assumed to be based on the NT
+  **       kernel.
+  */
+  return 1;
+#elif SQLITE_WIN32_GETVERSIONEX
+  if( osInterlockedCompareExchange(&sqlite3_os_type, 0, 0)==0 ){
+#if defined(SQLITE_WIN32_HAS_ANSI)
+    OSVERSIONINFOA sInfo;
+    sInfo.dwOSVersionInfoSize = sizeof(sInfo);
+    osGetVersionExA(&sInfo);
+    osInterlockedCompareExchange(&sqlite3_os_type,
+        (sInfo.dwPlatformId == VER_PLATFORM_WIN32_NT) ? 2 : 1, 0);
+#elif defined(SQLITE_WIN32_HAS_WIDE)
+    OSVERSIONINFOW sInfo;
+    sInfo.dwOSVersionInfoSize = sizeof(sInfo);
+    osGetVersionExW(&sInfo);
+    osInterlockedCompareExchange(&sqlite3_os_type,
+        (sInfo.dwPlatformId == VER_PLATFORM_WIN32_NT) ? 2 : 1, 0);
+#endif
+  }
+  return osInterlockedCompareExchange(&sqlite3_os_type, 2, 2)==2;
+#elif SQLITE_TEST
+  return osInterlockedCompareExchange(&sqlite3_os_type, 2, 2)==2;
+#else
+  /*
+  ** NOTE: All sub-platforms where the GetVersionEx[AW] functions are
+  **       deprecated are always assumed to be based on the NT kernel.
+  */
+  return 1;
+#endif
+}
+
+#ifdef SQLITE_WIN32_MALLOC
+/*
+** Allocate nBytes of memory.
+*/
+static void *winMemMalloc(int nBytes){
+  HANDLE hHeap;
+  void *p;
+
+  winMemAssertMagic();
+  hHeap = winMemGetHeap();
+  assert( hHeap!=0 );
+  assert( hHeap!=INVALID_HANDLE_VALUE );
+#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_MALLOC_VALIDATE)
+  assert( osHeapValidate(hHeap, SQLITE_WIN32_HEAP_FLAGS, NULL) );
+#endif
+  assert( nBytes>=0 );
+  p = osHeapAlloc(hHeap, SQLITE_WIN32_HEAP_FLAGS, (SIZE_T)nBytes);
+  if( !p ){
+    sqlite3_log(SQLITE_NOMEM, "failed to HeapAlloc %u bytes (%lu), heap=%p",
+                nBytes, osGetLastError(), (void*)hHeap);
+  }
+  return p;
+}
+
+/*
+** Free memory.
+*/
+static void winMemFree(void *pPrior){
+  HANDLE hHeap;
+
+  winMemAssertMagic();
+  hHeap = winMemGetHeap();
+  assert( hHeap!=0 );
+  assert( hHeap!=INVALID_HANDLE_VALUE );
+#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_MALLOC_VALIDATE)
+  assert( osHeapValidate(hHeap, SQLITE_WIN32_HEAP_FLAGS, pPrior) );
+#endif
+  if( !pPrior ) return; /* Passing NULL to HeapFree is undefined. */
+  if( !osHeapFree(hHeap, SQLITE_WIN32_HEAP_FLAGS, pPrior) ){
+    sqlite3_log(SQLITE_NOMEM, "failed to HeapFree block %p (%lu), heap=%p",
+                pPrior, osGetLastError(), (void*)hHeap);
+  }
+}
+
+/*
+** Change the size of an existing memory allocation
+*/
+static void *winMemRealloc(void *pPrior, int nBytes){
+  HANDLE hHeap;
+  void *p;
+
+  winMemAssertMagic();
+  hHeap = winMemGetHeap();
+  assert( hHeap!=0 );
+  assert( hHeap!=INVALID_HANDLE_VALUE );
+#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_MALLOC_VALIDATE)
+  assert( osHeapValidate(hHeap, SQLITE_WIN32_HEAP_FLAGS, pPrior) );
+#endif
+  assert( nBytes>=0 );
+  if( !pPrior ){
+    p = osHeapAlloc(hHeap, SQLITE_WIN32_HEAP_FLAGS, (SIZE_T)nBytes);
+  }else{
+    p = osHeapReAlloc(hHeap, SQLITE_WIN32_HEAP_FLAGS, pPrior, (SIZE_T)nBytes);
+  }
+  if( !p ){
+    sqlite3_log(SQLITE_NOMEM, "failed to %s %u bytes (%lu), heap=%p",
+                pPrior ? "HeapReAlloc" : "HeapAlloc", nBytes, osGetLastError(),
+                (void*)hHeap);
+  }
+  return p;
+}
+
+/*
+** Return the size of an outstanding allocation, in bytes.
+*/
+static int winMemSize(void *p){
+  HANDLE hHeap;
+  SIZE_T n;
+
+  winMemAssertMagic();
+  hHeap = winMemGetHeap();
+  assert( hHeap!=0 );
+  assert( hHeap!=INVALID_HANDLE_VALUE );
+#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_MALLOC_VALIDATE)
+  assert( osHeapValidate(hHeap, SQLITE_WIN32_HEAP_FLAGS, p) );
+#endif
+  if( !p ) return 0;
+  n = osHeapSize(hHeap, SQLITE_WIN32_HEAP_FLAGS, p);
+  if( n==(SIZE_T)-1 ){
+    sqlite3_log(SQLITE_NOMEM, "failed to HeapSize block %p (%lu), heap=%p",
+                p, osGetLastError(), (void*)hHeap);
+    return 0;
+  }
+  return (int)n;
+}
+
+/*
+** Round up a request size to the next valid allocation size.
+*/
+static int winMemRoundup(int n){
+  return n;
+}
+
+/*
+** Initialize this module.
+*/
+static int winMemInit(void *pAppData){
+  winMemData *pWinMemData = (winMemData *)pAppData;
+
+  if( !pWinMemData ) return SQLITE_ERROR;
+  assert( pWinMemData->magic1==WINMEM_MAGIC1 );
+  assert( pWinMemData->magic2==WINMEM_MAGIC2 );
+
+#if !SQLITE_OS_WINRT && SQLITE_WIN32_HEAP_CREATE
+  if( !pWinMemData->hHeap ){
+    DWORD dwInitialSize = SQLITE_WIN32_HEAP_INIT_SIZE;
+    DWORD dwMaximumSize = (DWORD)sqlite3GlobalConfig.nHeap;
+    if( dwMaximumSize==0 ){
+      dwMaximumSize = SQLITE_WIN32_HEAP_MAX_SIZE;
+    }else if( dwInitialSize>dwMaximumSize ){
+      dwInitialSize = dwMaximumSize;
+    }
+    pWinMemData->hHeap = osHeapCreate(SQLITE_WIN32_HEAP_FLAGS,
+                                      dwInitialSize, dwMaximumSize);
+    if( !pWinMemData->hHeap ){
+      sqlite3_log(SQLITE_NOMEM,
+          "failed to HeapCreate (%lu), flags=%u, initSize=%lu, maxSize=%lu",
+          osGetLastError(), SQLITE_WIN32_HEAP_FLAGS, dwInitialSize,
+          dwMaximumSize);
+      return SQLITE_NOMEM_BKPT;
+    }
+    pWinMemData->bOwned = TRUE;
+    assert( pWinMemData->bOwned );
+  }
+#else
+  pWinMemData->hHeap = osGetProcessHeap();
+  if( !pWinMemData->hHeap ){
+    sqlite3_log(SQLITE_NOMEM,
+        "failed to GetProcessHeap (%lu)", osGetLastError());
+    return SQLITE_NOMEM_BKPT;
+  }
+  pWinMemData->bOwned = FALSE;
+  assert( !pWinMemData->bOwned );
+#endif
+  assert( pWinMemData->hHeap!=0 );
+  assert( pWinMemData->hHeap!=INVALID_HANDLE_VALUE );
+#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_MALLOC_VALIDATE)
+  assert( osHeapValidate(pWinMemData->hHeap, SQLITE_WIN32_HEAP_FLAGS, NULL) );
+#endif
+  return SQLITE_OK;
+}
+
+/*
+** Deinitialize this module.
+*/
+static void winMemShutdown(void *pAppData){
+  winMemData *pWinMemData = (winMemData *)pAppData;
+
+  if( !pWinMemData ) return;
+  assert( pWinMemData->magic1==WINMEM_MAGIC1 );
+  assert( pWinMemData->magic2==WINMEM_MAGIC2 );
+
+  if( pWinMemData->hHeap ){
+    assert( pWinMemData->hHeap!=INVALID_HANDLE_VALUE );
+#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_MALLOC_VALIDATE)
+    assert( osHeapValidate(pWinMemData->hHeap, SQLITE_WIN32_HEAP_FLAGS, NULL) );
+#endif
+    if( pWinMemData->bOwned ){
+      if( !osHeapDestroy(pWinMemData->hHeap) ){
+        sqlite3_log(SQLITE_NOMEM, "failed to HeapDestroy (%lu), heap=%p",
+                    osGetLastError(), (void*)pWinMemData->hHeap);
+      }
+      pWinMemData->bOwned = FALSE;
+    }
+    pWinMemData->hHeap = NULL;
+  }
+}
+
+/*
+** Populate the low-level memory allocation function pointers in
+** sqlite3GlobalConfig.m with pointers to the routines in this file. The
+** arguments specify the block of memory to manage.
+**
+** This routine is only called by sqlite3_config(), and therefore
+** is not required to be threadsafe (it is not).
+*/
+SQLITE_PRIVATE const sqlite3_mem_methods *sqlite3MemGetWin32(void){
+  static const sqlite3_mem_methods winMemMethods = {
+    winMemMalloc,
+    winMemFree,
+    winMemRealloc,
+    winMemSize,
+    winMemRoundup,
+    winMemInit,
+    winMemShutdown,
+    &win_mem_data
+  };
+  return &winMemMethods;
+}
+
+SQLITE_PRIVATE void sqlite3MemSetDefault(void){
+  sqlite3_config(SQLITE_CONFIG_MALLOC, sqlite3MemGetWin32());
+}
+#endif /* SQLITE_WIN32_MALLOC */
+
+/*
+** Convert a UTF-8 string to Microsoft Unicode.
+**
+** Space to hold the returned string is obtained from sqlite3_malloc().
+*/
+static LPWSTR winUtf8ToUnicode(const char *zText){
+  int nChar;
+  LPWSTR zWideText;
+
+  nChar = osMultiByteToWideChar(CP_UTF8, 0, zText, -1, NULL, 0);
+  if( nChar==0 ){
+    return 0;
+  }
+  zWideText = sqlite3MallocZero( nChar*sizeof(WCHAR) );
+  if( zWideText==0 ){
+    return 0;
+  }
+  nChar = osMultiByteToWideChar(CP_UTF8, 0, zText, -1, zWideText,
+                                nChar);
+  if( nChar==0 ){
+    sqlite3_free(zWideText);
+    zWideText = 0;
+  }
+  return zWideText;
+}
+
+/*
+** Convert a Microsoft Unicode string to UTF-8.
+**
+** Space to hold the returned string is obtained from sqlite3_malloc().
+*/
+static char *winUnicodeToUtf8(LPCWSTR zWideText){
+  int nByte;
+  char *zText;
+
+  nByte = osWideCharToMultiByte(CP_UTF8, 0, zWideText, -1, 0, 0, 0, 0);
+  if( nByte == 0 ){
+    return 0;
+  }
+  zText = sqlite3MallocZero( nByte );
+  if( zText==0 ){
+    return 0;
+  }
+  nByte = osWideCharToMultiByte(CP_UTF8, 0, zWideText, -1, zText, nByte,
+                                0, 0);
+  if( nByte == 0 ){
+    sqlite3_free(zText);
+    zText = 0;
+  }
+  return zText;
+}
+
+/*
+** Convert an ANSI string to Microsoft Unicode, using the ANSI or OEM
+** code page.
+**
+** Space to hold the returned string is obtained from sqlite3_malloc().
+*/
+static LPWSTR winMbcsToUnicode(const char *zText, int useAnsi){
+  int nByte;
+  LPWSTR zMbcsText;
+  int codepage = useAnsi ? CP_ACP : CP_OEMCP;
+
+  nByte = osMultiByteToWideChar(codepage, 0, zText, -1, NULL,
+                                0)*sizeof(WCHAR);
+  if( nByte==0 ){
+    return 0;
+  }
+  zMbcsText = sqlite3MallocZero( nByte*sizeof(WCHAR) );
+  if( zMbcsText==0 ){
+    return 0;
+  }
+  nByte = osMultiByteToWideChar(codepage, 0, zText, -1, zMbcsText,
+                                nByte);
+  if( nByte==0 ){
+    sqlite3_free(zMbcsText);
+    zMbcsText = 0;
+  }
+  return zMbcsText;
+}
+
+/*
+** Convert a Microsoft Unicode string to a multi-byte character string,
+** using the ANSI or OEM code page.
+**
+** Space to hold the returned string is obtained from sqlite3_malloc().
+*/
+static char *winUnicodeToMbcs(LPCWSTR zWideText, int useAnsi){
+  int nByte;
+  char *zText;
+  int codepage = useAnsi ? CP_ACP : CP_OEMCP;
+
+  nByte = osWideCharToMultiByte(codepage, 0, zWideText, -1, 0, 0, 0, 0);
+  if( nByte == 0 ){
+    return 0;
+  }
+  zText = sqlite3MallocZero( nByte );
+  if( zText==0 ){
+    return 0;
+  }
+  nByte = osWideCharToMultiByte(codepage, 0, zWideText, -1, zText,
+                                nByte, 0, 0);
+  if( nByte == 0 ){
+    sqlite3_free(zText);
+    zText = 0;
+  }
+  return zText;
+}
+
+/*
+** Convert a multi-byte character string to UTF-8.
+**
+** Space to hold the returned string is obtained from sqlite3_malloc().
+*/
+static char *winMbcsToUtf8(const char *zText, int useAnsi){
+  char *zTextUtf8;
+  LPWSTR zTmpWide;
+
+  zTmpWide = winMbcsToUnicode(zText, useAnsi);
+  if( zTmpWide==0 ){
+    return 0;
+  }
+  zTextUtf8 = winUnicodeToUtf8(zTmpWide);
+  sqlite3_free(zTmpWide);
+  return zTextUtf8;
+}
+
+/*
+** Convert a UTF-8 string to a multi-byte character string.
+**
+** Space to hold the returned string is obtained from sqlite3_malloc().
+*/
+static char *winUtf8ToMbcs(const char *zText, int useAnsi){
+  char *zTextMbcs;
+  LPWSTR zTmpWide;
+
+  zTmpWide = winUtf8ToUnicode(zText);
+  if( zTmpWide==0 ){
+    return 0;
+  }
+  zTextMbcs = winUnicodeToMbcs(zTmpWide, useAnsi);
+  sqlite3_free(zTmpWide);
+  return zTextMbcs;
+}
+
+/*
+** This is a public wrapper for the winUtf8ToUnicode() function.
+*/
+SQLITE_API LPWSTR sqlite3_win32_utf8_to_unicode(const char *zText){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !zText ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  return winUtf8ToUnicode(zText);
+}
+
+/*
+** This is a public wrapper for the winUnicodeToUtf8() function.
+*/
+SQLITE_API char *sqlite3_win32_unicode_to_utf8(LPCWSTR zWideText){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !zWideText ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  return winUnicodeToUtf8(zWideText);
+}
+
+/*
+** This is a public wrapper for the winMbcsToUtf8() function.
+*/
+SQLITE_API char *sqlite3_win32_mbcs_to_utf8(const char *zText){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !zText ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  return winMbcsToUtf8(zText, osAreFileApisANSI());
+}
+
+/*
+** This is a public wrapper for the winMbcsToUtf8() function.
+*/
+SQLITE_API char *sqlite3_win32_mbcs_to_utf8_v2(const char *zText, int useAnsi){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !zText ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  return winMbcsToUtf8(zText, useAnsi);
+}
+
+/*
+** This is a public wrapper for the winUtf8ToMbcs() function.
+*/
+SQLITE_API char *sqlite3_win32_utf8_to_mbcs(const char *zText){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !zText ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  return winUtf8ToMbcs(zText, osAreFileApisANSI());
+}
+
+/*
+** This is a public wrapper for the winUtf8ToMbcs() function.
+*/
+SQLITE_API char *sqlite3_win32_utf8_to_mbcs_v2(const char *zText, int useAnsi){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !zText ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  return winUtf8ToMbcs(zText, useAnsi);
+}
+
+/*
+** This function sets the data directory or the temporary directory based on
+** the provided arguments.  The type argument must be 1 in order to set the
+** data directory or 2 in order to set the temporary directory.  The zValue
+** argument is the name of the directory to use.  The return value will be
+** SQLITE_OK if successful.
+*/
+SQLITE_API int sqlite3_win32_set_directory(DWORD type, LPCWSTR zValue){
+  char **ppDirectory = 0;
+#ifndef SQLITE_OMIT_AUTOINIT
+  int rc = sqlite3_initialize();
+  if( rc ) return rc;
+#endif
+  if( type==SQLITE_WIN32_DATA_DIRECTORY_TYPE ){
+    ppDirectory = &sqlite3_data_directory;
+  }else if( type==SQLITE_WIN32_TEMP_DIRECTORY_TYPE ){
+    ppDirectory = &sqlite3_temp_directory;
+  }
+  assert( !ppDirectory || type==SQLITE_WIN32_DATA_DIRECTORY_TYPE
+          || type==SQLITE_WIN32_TEMP_DIRECTORY_TYPE
+  );
+  assert( !ppDirectory || sqlite3MemdebugHasType(*ppDirectory, MEMTYPE_HEAP) );
+  if( ppDirectory ){
+    char *zValueUtf8 = 0;
+    if( zValue && zValue[0] ){
+      zValueUtf8 = winUnicodeToUtf8(zValue);
+      if ( zValueUtf8==0 ){
+        return SQLITE_NOMEM_BKPT;
+      }
+    }
+    sqlite3_free(*ppDirectory);
+    *ppDirectory = zValueUtf8;
+    return SQLITE_OK;
+  }
+  return SQLITE_ERROR;
+}
+
+/*
+** The return value of winGetLastErrorMsg
+** is zero if the error message fits in the buffer, or non-zero
+** otherwise (if the message was truncated).
+*/
+static int winGetLastErrorMsg(DWORD lastErrno, int nBuf, char *zBuf){
+  /* FormatMessage returns 0 on failure.  Otherwise it
+  ** returns the number of TCHARs written to the output
+  ** buffer, excluding the terminating null char.
+  */
+  DWORD dwLen = 0;
+  char *zOut = 0;
+
+  if( osIsNT() ){
+#if SQLITE_OS_WINRT
+    WCHAR zTempWide[SQLITE_WIN32_MAX_ERRMSG_CHARS+1];
+    dwLen = osFormatMessageW(FORMAT_MESSAGE_FROM_SYSTEM |
+                             FORMAT_MESSAGE_IGNORE_INSERTS,
+                             NULL,
+                             lastErrno,
+                             0,
+                             zTempWide,
+                             SQLITE_WIN32_MAX_ERRMSG_CHARS,
+                             0);
+#else
+    LPWSTR zTempWide = NULL;
+    dwLen = osFormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER |
+                             FORMAT_MESSAGE_FROM_SYSTEM |
+                             FORMAT_MESSAGE_IGNORE_INSERTS,
+                             NULL,
+                             lastErrno,
+                             0,
+                             (LPWSTR) &zTempWide,
+                             0,
+                             0);
+#endif
+    if( dwLen > 0 ){
+      /* allocate a buffer and convert to UTF8 */
+      sqlite3BeginBenignMalloc();
+      zOut = winUnicodeToUtf8(zTempWide);
+      sqlite3EndBenignMalloc();
+#if !SQLITE_OS_WINRT
+      /* free the system buffer allocated by FormatMessage */
+      osLocalFree(zTempWide);
+#endif
+    }
+  }
+#ifdef SQLITE_WIN32_HAS_ANSI
+  else{
+    char *zTemp = NULL;
+    dwLen = osFormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER |
+                             FORMAT_MESSAGE_FROM_SYSTEM |
+                             FORMAT_MESSAGE_IGNORE_INSERTS,
+                             NULL,
+                             lastErrno,
+                             0,
+                             (LPSTR) &zTemp,
+                             0,
+                             0);
+    if( dwLen > 0 ){
+      /* allocate a buffer and convert to UTF8 */
+      sqlite3BeginBenignMalloc();
+      zOut = winMbcsToUtf8(zTemp, osAreFileApisANSI());
+      sqlite3EndBenignMalloc();
+      /* free the system buffer allocated by FormatMessage */
+      osLocalFree(zTemp);
+    }
+  }
+#endif
+  if( 0 == dwLen ){
+    sqlite3_snprintf(nBuf, zBuf, "OsError 0x%lx (%lu)", lastErrno, lastErrno);
+  }else{
+    /* copy a maximum of nBuf chars to output buffer */
+    sqlite3_snprintf(nBuf, zBuf, "%s", zOut);
+    /* free the UTF8 buffer */
+    sqlite3_free(zOut);
+  }
+  return 0;
+}
+
+/*
+**
+** This function - winLogErrorAtLine() - is only ever called via the macro
+** winLogError().
+**
+** This routine is invoked after an error occurs in an OS function.
+** It logs a message using sqlite3_log() containing the current value of
+** error code and, if possible, the human-readable equivalent from
+** FormatMessage.
+**
+** The first argument passed to the macro should be the error code that
+** will be returned to SQLite (e.g. SQLITE_IOERR_DELETE, SQLITE_CANTOPEN).
+** The two subsequent arguments should be the name of the OS function that
+** failed and the associated file-system path, if any.
+*/
+#define winLogError(a,b,c,d)   winLogErrorAtLine(a,b,c,d,__LINE__)
+static int winLogErrorAtLine(
+  int errcode,                    /* SQLite error code */
+  DWORD lastErrno,                /* Win32 last error */
+  const char *zFunc,              /* Name of OS function that failed */
+  const char *zPath,              /* File path associated with error */
+  int iLine                       /* Source line number where error occurred */
+){
+  char zMsg[500];                 /* Human readable error text */
+  int i;                          /* Loop counter */
+
+  zMsg[0] = 0;
+  winGetLastErrorMsg(lastErrno, sizeof(zMsg), zMsg);
+  assert( errcode!=SQLITE_OK );
+  if( zPath==0 ) zPath = "";
+  for(i=0; zMsg[i] && zMsg[i]!='\r' && zMsg[i]!='\n'; i++){}
+  zMsg[i] = 0;
+  sqlite3_log(errcode,
+      "os_win.c:%d: (%lu) %s(%s) - %s",
+      iLine, lastErrno, zFunc, zPath, zMsg
+  );
+
+  return errcode;
+}
+
+/*
+** The number of times that a ReadFile(), WriteFile(), and DeleteFile()
+** will be retried following a locking error - probably caused by
+** antivirus software.  Also the initial delay before the first retry.
+** The delay increases linearly with each retry.
+*/
+#ifndef SQLITE_WIN32_IOERR_RETRY
+# define SQLITE_WIN32_IOERR_RETRY 10
+#endif
+#ifndef SQLITE_WIN32_IOERR_RETRY_DELAY
+# define SQLITE_WIN32_IOERR_RETRY_DELAY 25
+#endif
+static int winIoerrRetry = SQLITE_WIN32_IOERR_RETRY;
+static int winIoerrRetryDelay = SQLITE_WIN32_IOERR_RETRY_DELAY;
+
+/*
+** The "winIoerrCanRetry1" macro is used to determine if a particular I/O
+** error code obtained via GetLastError() is eligible to be retried.  It
+** must accept the error code DWORD as its only argument and should return
+** non-zero if the error code is transient in nature and the operation
+** responsible for generating the original error might succeed upon being
+** retried.  The argument to this macro should be a variable.
+**
+** Additionally, a macro named "winIoerrCanRetry2" may be defined.  If it
+** is defined, it will be consulted only when the macro "winIoerrCanRetry1"
+** returns zero.  The "winIoerrCanRetry2" macro is completely optional and
+** may be used to include additional error codes in the set that should
+** result in the failing I/O operation being retried by the caller.  If
+** defined, the "winIoerrCanRetry2" macro must exhibit external semantics
+** identical to those of the "winIoerrCanRetry1" macro.
+*/
+#if !defined(winIoerrCanRetry1)
+#define winIoerrCanRetry1(a) (((a)==ERROR_ACCESS_DENIED)        || \
+                              ((a)==ERROR_SHARING_VIOLATION)    || \
+                              ((a)==ERROR_LOCK_VIOLATION)       || \
+                              ((a)==ERROR_DEV_NOT_EXIST)        || \
+                              ((a)==ERROR_NETNAME_DELETED)      || \
+                              ((a)==ERROR_SEM_TIMEOUT)          || \
+                              ((a)==ERROR_NETWORK_UNREACHABLE))
+#endif
+
+/*
+** If a ReadFile() or WriteFile() error occurs, invoke this routine
+** to see if it should be retried.  Return TRUE to retry.  Return FALSE
+** to give up with an error.
+*/
+static int winRetryIoerr(int *pnRetry, DWORD *pError){
+  DWORD e = osGetLastError();
+  if( *pnRetry>=winIoerrRetry ){
+    if( pError ){
+      *pError = e;
+    }
+    return 0;
+  }
+  if( winIoerrCanRetry1(e) ){
+    sqlite3_win32_sleep(winIoerrRetryDelay*(1+*pnRetry));
+    ++*pnRetry;
+    return 1;
+  }
+#if defined(winIoerrCanRetry2)
+  else if( winIoerrCanRetry2(e) ){
+    sqlite3_win32_sleep(winIoerrRetryDelay*(1+*pnRetry));
+    ++*pnRetry;
+    return 1;
+  }
+#endif
+  if( pError ){
+    *pError = e;
+  }
+  return 0;
+}
+
+/*
+** Log a I/O error retry episode.
+*/
+static void winLogIoerr(int nRetry, int lineno){
+  if( nRetry ){
+    sqlite3_log(SQLITE_NOTICE,
+      "delayed %dms for lock/sharing conflict at line %d",
+      winIoerrRetryDelay*nRetry*(nRetry+1)/2, lineno
+    );
+  }
+}
+
+/*
+** This #if does not rely on the SQLITE_OS_WINCE define because the
+** corresponding section in "date.c" cannot use it.
+*/
+#if !defined(SQLITE_OMIT_LOCALTIME) && defined(_WIN32_WCE) && \
+    (!defined(SQLITE_MSVC_LOCALTIME_API) || !SQLITE_MSVC_LOCALTIME_API)
+/*
+** The MSVC CRT on Windows CE may not have a localtime() function.
+** So define a substitute.
+*/
+/* #  include <time.h> */
+struct tm *__cdecl localtime(const time_t *t)
+{
+  static struct tm y;
+  FILETIME uTm, lTm;
+  SYSTEMTIME pTm;
+  sqlite3_int64 t64;
+  t64 = *t;
+  t64 = (t64 + 11644473600)*10000000;
+  uTm.dwLowDateTime = (DWORD)(t64 & 0xFFFFFFFF);
+  uTm.dwHighDateTime= (DWORD)(t64 >> 32);
+  osFileTimeToLocalFileTime(&uTm,&lTm);
+  osFileTimeToSystemTime(&lTm,&pTm);
+  y.tm_year = pTm.wYear - 1900;
+  y.tm_mon = pTm.wMonth - 1;
+  y.tm_wday = pTm.wDayOfWeek;
+  y.tm_mday = pTm.wDay;
+  y.tm_hour = pTm.wHour;
+  y.tm_min = pTm.wMinute;
+  y.tm_sec = pTm.wSecond;
+  return &y;
+}
+#endif
+
+#if SQLITE_OS_WINCE
+/*************************************************************************
+** This section contains code for WinCE only.
+*/
+#define HANDLE_TO_WINFILE(a) (winFile*)&((char*)a)[-(int)offsetof(winFile,h)]
+
+/*
+** Acquire a lock on the handle h
+*/
+static void winceMutexAcquire(HANDLE h){
+   DWORD dwErr;
+   do {
+     dwErr = osWaitForSingleObject(h, INFINITE);
+   } while (dwErr != WAIT_OBJECT_0 && dwErr != WAIT_ABANDONED);
+}
+/*
+** Release a lock acquired by winceMutexAcquire()
+*/
+#define winceMutexRelease(h) ReleaseMutex(h)
+
+/*
+** Create the mutex and shared memory used for locking in the file
+** descriptor pFile
+*/
+static int winceCreateLock(const char *zFilename, winFile *pFile){
+  LPWSTR zTok;
+  LPWSTR zName;
+  DWORD lastErrno;
+  BOOL bLogged = FALSE;
+  BOOL bInit = TRUE;
+
+  zName = winUtf8ToUnicode(zFilename);
+  if( zName==0 ){
+    /* out of memory */
+    return SQLITE_IOERR_NOMEM_BKPT;
+  }
+
+  /* Initialize the local lockdata */
+  memset(&pFile->local, 0, sizeof(pFile->local));
+
+  /* Replace the backslashes from the filename and lowercase it
+  ** to derive a mutex name. */
+  zTok = osCharLowerW(zName);
+  for (;*zTok;zTok++){
+    if (*zTok == '\\') *zTok = '_';
+  }
+
+  /* Create/open the named mutex */
+  pFile->hMutex = osCreateMutexW(NULL, FALSE, zName);
+  if (!pFile->hMutex){
+    pFile->lastErrno = osGetLastError();
+    sqlite3_free(zName);
+    return winLogError(SQLITE_IOERR, pFile->lastErrno,
+                       "winceCreateLock1", zFilename);
+  }
+
+  /* Acquire the mutex before continuing */
+  winceMutexAcquire(pFile->hMutex);
+
+  /* Since the names of named mutexes, semaphores, file mappings etc are
+  ** case-sensitive, take advantage of that by uppercasing the mutex name
+  ** and using that as the shared filemapping name.
+  */
+  osCharUpperW(zName);
+  pFile->hShared = osCreateFileMappingW(INVALID_HANDLE_VALUE, NULL,
+                                        PAGE_READWRITE, 0, sizeof(winceLock),
+                                        zName);
+
+  /* Set a flag that indicates we're the first to create the memory so it
+  ** must be zero-initialized */
+  lastErrno = osGetLastError();
+  if (lastErrno == ERROR_ALREADY_EXISTS){
+    bInit = FALSE;
+  }
+
+  sqlite3_free(zName);
+
+  /* If we succeeded in making the shared memory handle, map it. */
+  if( pFile->hShared ){
+    pFile->shared = (winceLock*)osMapViewOfFile(pFile->hShared,
+             FILE_MAP_READ|FILE_MAP_WRITE, 0, 0, sizeof(winceLock));
+    /* If mapping failed, close the shared memory handle and erase it */
+    if( !pFile->shared ){
+      pFile->lastErrno = osGetLastError();
+      winLogError(SQLITE_IOERR, pFile->lastErrno,
+                  "winceCreateLock2", zFilename);
+      bLogged = TRUE;
+      osCloseHandle(pFile->hShared);
+      pFile->hShared = NULL;
+    }
+  }
+
+  /* If shared memory could not be created, then close the mutex and fail */
+  if( pFile->hShared==NULL ){
+    if( !bLogged ){
+      pFile->lastErrno = lastErrno;
+      winLogError(SQLITE_IOERR, pFile->lastErrno,
+                  "winceCreateLock3", zFilename);
+      bLogged = TRUE;
+    }
+    winceMutexRelease(pFile->hMutex);
+    osCloseHandle(pFile->hMutex);
+    pFile->hMutex = NULL;
+    return SQLITE_IOERR;
+  }
+
+  /* Initialize the shared memory if we're supposed to */
+  if( bInit ){
+    memset(pFile->shared, 0, sizeof(winceLock));
+  }
+
+  winceMutexRelease(pFile->hMutex);
+  return SQLITE_OK;
+}
+
+/*
+** Destroy the part of winFile that deals with wince locks
+*/
+static void winceDestroyLock(winFile *pFile){
+  if (pFile->hMutex){
+    /* Acquire the mutex */
+    winceMutexAcquire(pFile->hMutex);
+
+    /* The following blocks should probably assert in debug mode, but they
+       are to cleanup in case any locks remained open */
+    if (pFile->local.nReaders){
+      pFile->shared->nReaders --;
+    }
+    if (pFile->local.bReserved){
+      pFile->shared->bReserved = FALSE;
+    }
+    if (pFile->local.bPending){
+      pFile->shared->bPending = FALSE;
+    }
+    if (pFile->local.bExclusive){
+      pFile->shared->bExclusive = FALSE;
+    }
+
+    /* De-reference and close our copy of the shared memory handle */
+    osUnmapViewOfFile(pFile->shared);
+    osCloseHandle(pFile->hShared);
+
+    /* Done with the mutex */
+    winceMutexRelease(pFile->hMutex);
+    osCloseHandle(pFile->hMutex);
+    pFile->hMutex = NULL;
+  }
+}
+
+/*
+** An implementation of the LockFile() API of Windows for CE
+*/
+static BOOL winceLockFile(
+  LPHANDLE phFile,
+  DWORD dwFileOffsetLow,
+  DWORD dwFileOffsetHigh,
+  DWORD nNumberOfBytesToLockLow,
+  DWORD nNumberOfBytesToLockHigh
+){
+  winFile *pFile = HANDLE_TO_WINFILE(phFile);
+  BOOL bReturn = FALSE;
+
+  UNUSED_PARAMETER(dwFileOffsetHigh);
+  UNUSED_PARAMETER(nNumberOfBytesToLockHigh);
+
+  if (!pFile->hMutex) return TRUE;
+  winceMutexAcquire(pFile->hMutex);
+
+  /* Wanting an exclusive lock? */
+  if (dwFileOffsetLow == (DWORD)SHARED_FIRST
+       && nNumberOfBytesToLockLow == (DWORD)SHARED_SIZE){
+    if (pFile->shared->nReaders == 0 && pFile->shared->bExclusive == 0){
+       pFile->shared->bExclusive = TRUE;
+       pFile->local.bExclusive = TRUE;
+       bReturn = TRUE;
+    }
+  }
+
+  /* Want a read-only lock? */
+  else if (dwFileOffsetLow == (DWORD)SHARED_FIRST &&
+           nNumberOfBytesToLockLow == 1){
+    if (pFile->shared->bExclusive == 0){
+      pFile->local.nReaders ++;
+      if (pFile->local.nReaders == 1){
+        pFile->shared->nReaders ++;
+      }
+      bReturn = TRUE;
+    }
+  }
+
+  /* Want a pending lock? */
+  else if (dwFileOffsetLow == (DWORD)PENDING_BYTE
+           && nNumberOfBytesToLockLow == 1){
+    /* If no pending lock has been acquired, then acquire it */
+    if (pFile->shared->bPending == 0) {
+      pFile->shared->bPending = TRUE;
+      pFile->local.bPending = TRUE;
+      bReturn = TRUE;
+    }
+  }
+
+  /* Want a reserved lock? */
+  else if (dwFileOffsetLow == (DWORD)RESERVED_BYTE
+           && nNumberOfBytesToLockLow == 1){
+    if (pFile->shared->bReserved == 0) {
+      pFile->shared->bReserved = TRUE;
+      pFile->local.bReserved = TRUE;
+      bReturn = TRUE;
+    }
+  }
+
+  winceMutexRelease(pFile->hMutex);
+  return bReturn;
+}
+
+/*
+** An implementation of the UnlockFile API of Windows for CE
+*/
+static BOOL winceUnlockFile(
+  LPHANDLE phFile,
+  DWORD dwFileOffsetLow,
+  DWORD dwFileOffsetHigh,
+  DWORD nNumberOfBytesToUnlockLow,
+  DWORD nNumberOfBytesToUnlockHigh
+){
+  winFile *pFile = HANDLE_TO_WINFILE(phFile);
+  BOOL bReturn = FALSE;
+
+  UNUSED_PARAMETER(dwFileOffsetHigh);
+  UNUSED_PARAMETER(nNumberOfBytesToUnlockHigh);
+
+  if (!pFile->hMutex) return TRUE;
+  winceMutexAcquire(pFile->hMutex);
+
+  /* Releasing a reader lock or an exclusive lock */
+  if (dwFileOffsetLow == (DWORD)SHARED_FIRST){
+    /* Did we have an exclusive lock? */
+    if (pFile->local.bExclusive){
+      assert(nNumberOfBytesToUnlockLow == (DWORD)SHARED_SIZE);
+      pFile->local.bExclusive = FALSE;
+      pFile->shared->bExclusive = FALSE;
+      bReturn = TRUE;
+    }
+
+    /* Did we just have a reader lock? */
+    else if (pFile->local.nReaders){
+      assert(nNumberOfBytesToUnlockLow == (DWORD)SHARED_SIZE
+             || nNumberOfBytesToUnlockLow == 1);
+      pFile->local.nReaders --;
+      if (pFile->local.nReaders == 0)
+      {
+        pFile->shared->nReaders --;
+      }
+      bReturn = TRUE;
+    }
+  }
+
+  /* Releasing a pending lock */
+  else if (dwFileOffsetLow == (DWORD)PENDING_BYTE
+           && nNumberOfBytesToUnlockLow == 1){
+    if (pFile->local.bPending){
+      pFile->local.bPending = FALSE;
+      pFile->shared->bPending = FALSE;
+      bReturn = TRUE;
+    }
+  }
+  /* Releasing a reserved lock */
+  else if (dwFileOffsetLow == (DWORD)RESERVED_BYTE
+           && nNumberOfBytesToUnlockLow == 1){
+    if (pFile->local.bReserved) {
+      pFile->local.bReserved = FALSE;
+      pFile->shared->bReserved = FALSE;
+      bReturn = TRUE;
+    }
+  }
+
+  winceMutexRelease(pFile->hMutex);
+  return bReturn;
+}
+/*
+** End of the special code for wince
+*****************************************************************************/
+#endif /* SQLITE_OS_WINCE */
+
+/*
+** Lock a file region.
+*/
+static BOOL winLockFile(
+  LPHANDLE phFile,
+  DWORD flags,
+  DWORD offsetLow,
+  DWORD offsetHigh,
+  DWORD numBytesLow,
+  DWORD numBytesHigh
+){
+#if SQLITE_OS_WINCE
+  /*
+  ** NOTE: Windows CE is handled differently here due its lack of the Win32
+  **       API LockFile.
+  */
+  return winceLockFile(phFile, offsetLow, offsetHigh,
+                       numBytesLow, numBytesHigh);
+#else
+  if( osIsNT() ){
+    OVERLAPPED ovlp;
+    memset(&ovlp, 0, sizeof(OVERLAPPED));
+    ovlp.Offset = offsetLow;
+    ovlp.OffsetHigh = offsetHigh;
+    return osLockFileEx(*phFile, flags, 0, numBytesLow, numBytesHigh, &ovlp);
+  }else{
+    return osLockFile(*phFile, offsetLow, offsetHigh, numBytesLow,
+                      numBytesHigh);
+  }
+#endif
+}
+
+/*
+** Unlock a file region.
+ */
+static BOOL winUnlockFile(
+  LPHANDLE phFile,
+  DWORD offsetLow,
+  DWORD offsetHigh,
+  DWORD numBytesLow,
+  DWORD numBytesHigh
+){
+#if SQLITE_OS_WINCE
+  /*
+  ** NOTE: Windows CE is handled differently here due its lack of the Win32
+  **       API UnlockFile.
+  */
+  return winceUnlockFile(phFile, offsetLow, offsetHigh,
+                         numBytesLow, numBytesHigh);
+#else
+  if( osIsNT() ){
+    OVERLAPPED ovlp;
+    memset(&ovlp, 0, sizeof(OVERLAPPED));
+    ovlp.Offset = offsetLow;
+    ovlp.OffsetHigh = offsetHigh;
+    return osUnlockFileEx(*phFile, 0, numBytesLow, numBytesHigh, &ovlp);
+  }else{
+    return osUnlockFile(*phFile, offsetLow, offsetHigh, numBytesLow,
+                        numBytesHigh);
+  }
+#endif
+}
+
+/*****************************************************************************
+** The next group of routines implement the I/O methods specified
+** by the sqlite3_io_methods object.
+******************************************************************************/
+
+/*
+** Some Microsoft compilers lack this definition.
+*/
+#ifndef INVALID_SET_FILE_POINTER
+# define INVALID_SET_FILE_POINTER ((DWORD)-1)
+#endif
+
+/*
+** Move the current position of the file handle passed as the first
+** argument to offset iOffset within the file. If successful, return 0.
+** Otherwise, set pFile->lastErrno and return non-zero.
+*/
+static int winSeekFile(winFile *pFile, sqlite3_int64 iOffset){
+#if !SQLITE_OS_WINRT
+  LONG upperBits;                 /* Most sig. 32 bits of new offset */
+  LONG lowerBits;                 /* Least sig. 32 bits of new offset */
+  DWORD dwRet;                    /* Value returned by SetFilePointer() */
+  DWORD lastErrno;                /* Value returned by GetLastError() */
+
+  OSTRACE(("SEEK file=%p, offset=%lld\n", pFile->h, iOffset));
+
+  upperBits = (LONG)((iOffset>>32) & 0x7fffffff);
+  lowerBits = (LONG)(iOffset & 0xffffffff);
+
+  /* API oddity: If successful, SetFilePointer() returns a dword
+  ** containing the lower 32-bits of the new file-offset. Or, if it fails,
+  ** it returns INVALID_SET_FILE_POINTER. However according to MSDN,
+  ** INVALID_SET_FILE_POINTER may also be a valid new offset. So to determine
+  ** whether an error has actually occurred, it is also necessary to call
+  ** GetLastError().
+  */
+  dwRet = osSetFilePointer(pFile->h, lowerBits, &upperBits, FILE_BEGIN);
+
+  if( (dwRet==INVALID_SET_FILE_POINTER
+      && ((lastErrno = osGetLastError())!=NO_ERROR)) ){
+    pFile->lastErrno = lastErrno;
+    winLogError(SQLITE_IOERR_SEEK, pFile->lastErrno,
+                "winSeekFile", pFile->zPath);
+    OSTRACE(("SEEK file=%p, rc=SQLITE_IOERR_SEEK\n", pFile->h));
+    return 1;
+  }
+
+  OSTRACE(("SEEK file=%p, rc=SQLITE_OK\n", pFile->h));
+  return 0;
+#else
+  /*
+  ** Same as above, except that this implementation works for WinRT.
+  */
+
+  LARGE_INTEGER x;                /* The new offset */
+  BOOL bRet;                      /* Value returned by SetFilePointerEx() */
+
+  x.QuadPart = iOffset;
+  bRet = osSetFilePointerEx(pFile->h, x, 0, FILE_BEGIN);
+
+  if(!bRet){
+    pFile->lastErrno = osGetLastError();
+    winLogError(SQLITE_IOERR_SEEK, pFile->lastErrno,
+                "winSeekFile", pFile->zPath);
+    OSTRACE(("SEEK file=%p, rc=SQLITE_IOERR_SEEK\n", pFile->h));
+    return 1;
+  }
+
+  OSTRACE(("SEEK file=%p, rc=SQLITE_OK\n", pFile->h));
+  return 0;
+#endif
+}
+
+#if SQLITE_MAX_MMAP_SIZE>0
+/* Forward references to VFS helper methods used for memory mapped files */
+static int winMapfile(winFile*, sqlite3_int64);
+static int winUnmapfile(winFile*);
+#endif
+
+/*
+** Close a file.
+**
+** It is reported that an attempt to close a handle might sometimes
+** fail.  This is a very unreasonable result, but Windows is notorious
+** for being unreasonable so I do not doubt that it might happen.  If
+** the close fails, we pause for 100 milliseconds and try again.  As
+** many as MX_CLOSE_ATTEMPT attempts to close the handle are made before
+** giving up and returning an error.
+*/
+#define MX_CLOSE_ATTEMPT 3
+static int winClose(sqlite3_file *id){
+  int rc, cnt = 0;
+  winFile *pFile = (winFile*)id;
+
+  assert( id!=0 );
+#ifndef SQLITE_OMIT_WAL
+  assert( pFile->pShm==0 );
+#endif
+  assert( pFile->h!=NULL && pFile->h!=INVALID_HANDLE_VALUE );
+  OSTRACE(("CLOSE pid=%lu, pFile=%p, file=%p\n",
+           osGetCurrentProcessId(), pFile, pFile->h));
+
+#if SQLITE_MAX_MMAP_SIZE>0
+  winUnmapfile(pFile);
+#endif
+
+  do{
+    rc = osCloseHandle(pFile->h);
+    /* SimulateIOError( rc=0; cnt=MX_CLOSE_ATTEMPT; ); */
+  }while( rc==0 && ++cnt < MX_CLOSE_ATTEMPT && (sqlite3_win32_sleep(100), 1) );
+#if SQLITE_OS_WINCE
+#define WINCE_DELETION_ATTEMPTS 3
+  {
+    winVfsAppData *pAppData = (winVfsAppData*)pFile->pVfs->pAppData;
+    if( pAppData==NULL || !pAppData->bNoLock ){
+      winceDestroyLock(pFile);
+    }
+  }
+  if( pFile->zDeleteOnClose ){
+    int cnt = 0;
+    while(
+           osDeleteFileW(pFile->zDeleteOnClose)==0
+        && osGetFileAttributesW(pFile->zDeleteOnClose)!=0xffffffff
+        && cnt++ < WINCE_DELETION_ATTEMPTS
+    ){
+       sqlite3_win32_sleep(100);  /* Wait a little before trying again */
+    }
+    sqlite3_free(pFile->zDeleteOnClose);
+  }
+#endif
+  if( rc ){
+    pFile->h = NULL;
+  }
+  OpenCounter(-1);
+  OSTRACE(("CLOSE pid=%lu, pFile=%p, file=%p, rc=%s\n",
+           osGetCurrentProcessId(), pFile, pFile->h, rc ? "ok" : "failed"));
+  return rc ? SQLITE_OK
+            : winLogError(SQLITE_IOERR_CLOSE, osGetLastError(),
+                          "winClose", pFile->zPath);
+}
+
+/*
+** Read data from a file into a buffer.  Return SQLITE_OK if all
+** bytes were read successfully and SQLITE_IOERR if anything goes
+** wrong.
+*/
+static int winRead(
+  sqlite3_file *id,          /* File to read from */
+  void *pBuf,                /* Write content into this buffer */
+  int amt,                   /* Number of bytes to read */
+  sqlite3_int64 offset       /* Begin reading at this offset */
+){
+#if !SQLITE_OS_WINCE && !defined(SQLITE_WIN32_NO_OVERLAPPED)
+  OVERLAPPED overlapped;          /* The offset for ReadFile. */
+#endif
+  winFile *pFile = (winFile*)id;  /* file handle */
+  DWORD nRead;                    /* Number of bytes actually read from file */
+  int nRetry = 0;                 /* Number of retrys */
+
+  assert( id!=0 );
+  assert( amt>0 );
+  assert( offset>=0 );
+  SimulateIOError(return SQLITE_IOERR_READ);
+  OSTRACE(("READ pid=%lu, pFile=%p, file=%p, buffer=%p, amount=%d, "
+           "offset=%lld, lock=%d\n", osGetCurrentProcessId(), pFile,
+           pFile->h, pBuf, amt, offset, pFile->locktype));
+
+#if SQLITE_MAX_MMAP_SIZE>0
+  /* Deal with as much of this read request as possible by transfering
+  ** data from the memory mapping using memcpy().  */
+  if( offset<pFile->mmapSize ){
+    if( offset+amt <= pFile->mmapSize ){
+      memcpy(pBuf, &((u8 *)(pFile->pMapRegion))[offset], amt);
+      OSTRACE(("READ-MMAP pid=%lu, pFile=%p, file=%p, rc=SQLITE_OK\n",
+               osGetCurrentProcessId(), pFile, pFile->h));
+      return SQLITE_OK;
+    }else{
+      int nCopy = (int)(pFile->mmapSize - offset);
+      memcpy(pBuf, &((u8 *)(pFile->pMapRegion))[offset], nCopy);
+      pBuf = &((u8 *)pBuf)[nCopy];
+      amt -= nCopy;
+      offset += nCopy;
+    }
+  }
+#endif
+
+#if SQLITE_OS_WINCE || defined(SQLITE_WIN32_NO_OVERLAPPED)
+  if( winSeekFile(pFile, offset) ){
+    OSTRACE(("READ pid=%lu, pFile=%p, file=%p, rc=SQLITE_FULL\n",
+             osGetCurrentProcessId(), pFile, pFile->h));
+    return SQLITE_FULL;
+  }
+  while( !osReadFile(pFile->h, pBuf, amt, &nRead, 0) ){
+#else
+  memset(&overlapped, 0, sizeof(OVERLAPPED));
+  overlapped.Offset = (LONG)(offset & 0xffffffff);
+  overlapped.OffsetHigh = (LONG)((offset>>32) & 0x7fffffff);
+  while( !osReadFile(pFile->h, pBuf, amt, &nRead, &overlapped) &&
+         osGetLastError()!=ERROR_HANDLE_EOF ){
+#endif
+    DWORD lastErrno;
+    if( winRetryIoerr(&nRetry, &lastErrno) ) continue;
+    pFile->lastErrno = lastErrno;
+    OSTRACE(("READ pid=%lu, pFile=%p, file=%p, rc=SQLITE_IOERR_READ\n",
+             osGetCurrentProcessId(), pFile, pFile->h));
+    return winLogError(SQLITE_IOERR_READ, pFile->lastErrno,
+                       "winRead", pFile->zPath);
+  }
+  winLogIoerr(nRetry, __LINE__);
+  if( nRead<(DWORD)amt ){
+    /* Unread parts of the buffer must be zero-filled */
+    memset(&((char*)pBuf)[nRead], 0, amt-nRead);
+    OSTRACE(("READ pid=%lu, pFile=%p, file=%p, rc=SQLITE_IOERR_SHORT_READ\n",
+             osGetCurrentProcessId(), pFile, pFile->h));
+    return SQLITE_IOERR_SHORT_READ;
+  }
+
+  OSTRACE(("READ pid=%lu, pFile=%p, file=%p, rc=SQLITE_OK\n",
+           osGetCurrentProcessId(), pFile, pFile->h));
+  return SQLITE_OK;
+}
+
+/*
+** Write data from a buffer into a file.  Return SQLITE_OK on success
+** or some other error code on failure.
+*/
+static int winWrite(
+  sqlite3_file *id,               /* File to write into */
+  const void *pBuf,               /* The bytes to be written */
+  int amt,                        /* Number of bytes to write */
+  sqlite3_int64 offset            /* Offset into the file to begin writing at */
+){
+  int rc = 0;                     /* True if error has occurred, else false */
+  winFile *pFile = (winFile*)id;  /* File handle */
+  int nRetry = 0;                 /* Number of retries */
+
+  assert( amt>0 );
+  assert( pFile );
+  SimulateIOError(return SQLITE_IOERR_WRITE);
+  SimulateDiskfullError(return SQLITE_FULL);
+
+  OSTRACE(("WRITE pid=%lu, pFile=%p, file=%p, buffer=%p, amount=%d, "
+           "offset=%lld, lock=%d\n", osGetCurrentProcessId(), pFile,
+           pFile->h, pBuf, amt, offset, pFile->locktype));
+
+#if defined(SQLITE_MMAP_READWRITE) && SQLITE_MAX_MMAP_SIZE>0
+  /* Deal with as much of this write request as possible by transfering
+  ** data from the memory mapping using memcpy().  */
+  if( offset<pFile->mmapSize ){
+    if( offset+amt <= pFile->mmapSize ){
+      memcpy(&((u8 *)(pFile->pMapRegion))[offset], pBuf, amt);
+      OSTRACE(("WRITE-MMAP pid=%lu, pFile=%p, file=%p, rc=SQLITE_OK\n",
+               osGetCurrentProcessId(), pFile, pFile->h));
+      return SQLITE_OK;
+    }else{
+      int nCopy = (int)(pFile->mmapSize - offset);
+      memcpy(&((u8 *)(pFile->pMapRegion))[offset], pBuf, nCopy);
+      pBuf = &((u8 *)pBuf)[nCopy];
+      amt -= nCopy;
+      offset += nCopy;
+    }
+  }
+#endif
+
+#if SQLITE_OS_WINCE || defined(SQLITE_WIN32_NO_OVERLAPPED)
+  rc = winSeekFile(pFile, offset);
+  if( rc==0 ){
+#else
+  {
+#endif
+#if !SQLITE_OS_WINCE && !defined(SQLITE_WIN32_NO_OVERLAPPED)
+    OVERLAPPED overlapped;        /* The offset for WriteFile. */
+#endif
+    u8 *aRem = (u8 *)pBuf;        /* Data yet to be written */
+    int nRem = amt;               /* Number of bytes yet to be written */
+    DWORD nWrite;                 /* Bytes written by each WriteFile() call */
+    DWORD lastErrno = NO_ERROR;   /* Value returned by GetLastError() */
+
+#if !SQLITE_OS_WINCE && !defined(SQLITE_WIN32_NO_OVERLAPPED)
+    memset(&overlapped, 0, sizeof(OVERLAPPED));
+    overlapped.Offset = (LONG)(offset & 0xffffffff);
+    overlapped.OffsetHigh = (LONG)((offset>>32) & 0x7fffffff);
+#endif
+
+    while( nRem>0 ){
+#if SQLITE_OS_WINCE || defined(SQLITE_WIN32_NO_OVERLAPPED)
+      if( !osWriteFile(pFile->h, aRem, nRem, &nWrite, 0) ){
+#else
+      if( !osWriteFile(pFile->h, aRem, nRem, &nWrite, &overlapped) ){
+#endif
+        if( winRetryIoerr(&nRetry, &lastErrno) ) continue;
+        break;
+      }
+      assert( nWrite==0 || nWrite<=(DWORD)nRem );
+      if( nWrite==0 || nWrite>(DWORD)nRem ){
+        lastErrno = osGetLastError();
+        break;
+      }
+#if !SQLITE_OS_WINCE && !defined(SQLITE_WIN32_NO_OVERLAPPED)
+      offset += nWrite;
+      overlapped.Offset = (LONG)(offset & 0xffffffff);
+      overlapped.OffsetHigh = (LONG)((offset>>32) & 0x7fffffff);
+#endif
+      aRem += nWrite;
+      nRem -= nWrite;
+    }
+    if( nRem>0 ){
+      pFile->lastErrno = lastErrno;
+      rc = 1;
+    }
+  }
+
+  if( rc ){
+    if(   ( pFile->lastErrno==ERROR_HANDLE_DISK_FULL )
+       || ( pFile->lastErrno==ERROR_DISK_FULL )){
+      OSTRACE(("WRITE pid=%lu, pFile=%p, file=%p, rc=SQLITE_FULL\n",
+               osGetCurrentProcessId(), pFile, pFile->h));
+      return winLogError(SQLITE_FULL, pFile->lastErrno,
+                         "winWrite1", pFile->zPath);
+    }
+    OSTRACE(("WRITE pid=%lu, pFile=%p, file=%p, rc=SQLITE_IOERR_WRITE\n",
+             osGetCurrentProcessId(), pFile, pFile->h));
+    return winLogError(SQLITE_IOERR_WRITE, pFile->lastErrno,
+                       "winWrite2", pFile->zPath);
+  }else{
+    winLogIoerr(nRetry, __LINE__);
+  }
+  OSTRACE(("WRITE pid=%lu, pFile=%p, file=%p, rc=SQLITE_OK\n",
+           osGetCurrentProcessId(), pFile, pFile->h));
+  return SQLITE_OK;
+}
+
+/*
+** Truncate an open file to a specified size
+*/
+static int winTruncate(sqlite3_file *id, sqlite3_int64 nByte){
+  winFile *pFile = (winFile*)id;  /* File handle object */
+  int rc = SQLITE_OK;             /* Return code for this function */
+  DWORD lastErrno;
+
+  assert( pFile );
+  SimulateIOError(return SQLITE_IOERR_TRUNCATE);
+  OSTRACE(("TRUNCATE pid=%lu, pFile=%p, file=%p, size=%lld, lock=%d\n",
+           osGetCurrentProcessId(), pFile, pFile->h, nByte, pFile->locktype));
+
+  /* If the user has configured a chunk-size for this file, truncate the
+  ** file so that it consists of an integer number of chunks (i.e. the
+  ** actual file size after the operation may be larger than the requested
+  ** size).
+  */
+  if( pFile->szChunk>0 ){
+    nByte = ((nByte + pFile->szChunk - 1)/pFile->szChunk) * pFile->szChunk;
+  }
+
+  /* SetEndOfFile() returns non-zero when successful, or zero when it fails. */
+  if( winSeekFile(pFile, nByte) ){
+    rc = winLogError(SQLITE_IOERR_TRUNCATE, pFile->lastErrno,
+                     "winTruncate1", pFile->zPath);
+  }else if( 0==osSetEndOfFile(pFile->h) &&
+            ((lastErrno = osGetLastError())!=ERROR_USER_MAPPED_FILE) ){
+    pFile->lastErrno = lastErrno;
+    rc = winLogError(SQLITE_IOERR_TRUNCATE, pFile->lastErrno,
+                     "winTruncate2", pFile->zPath);
+  }
+
+#if SQLITE_MAX_MMAP_SIZE>0
+  /* If the file was truncated to a size smaller than the currently
+  ** mapped region, reduce the effective mapping size as well. SQLite will
+  ** use read() and write() to access data beyond this point from now on.
+  */
+  if( pFile->pMapRegion && nByte<pFile->mmapSize ){
+    pFile->mmapSize = nByte;
+  }
+#endif
+
+  OSTRACE(("TRUNCATE pid=%lu, pFile=%p, file=%p, rc=%s\n",
+           osGetCurrentProcessId(), pFile, pFile->h, sqlite3ErrName(rc)));
+  return rc;
+}
+
+#ifdef SQLITE_TEST
+/*
+** Count the number of fullsyncs and normal syncs.  This is used to test
+** that syncs and fullsyncs are occuring at the right times.
+*/
+SQLITE_API int sqlite3_sync_count = 0;
+SQLITE_API int sqlite3_fullsync_count = 0;
+#endif
+
+/*
+** Make sure all writes to a particular file are committed to disk.
+*/
+static int winSync(sqlite3_file *id, int flags){
+#ifndef SQLITE_NO_SYNC
+  /*
+  ** Used only when SQLITE_NO_SYNC is not defined.
+   */
+  BOOL rc;
+#endif
+#if !defined(NDEBUG) || !defined(SQLITE_NO_SYNC) || \
+    defined(SQLITE_HAVE_OS_TRACE)
+  /*
+  ** Used when SQLITE_NO_SYNC is not defined and by the assert() and/or
+  ** OSTRACE() macros.
+   */
+  winFile *pFile = (winFile*)id;
+#else
+  UNUSED_PARAMETER(id);
+#endif
+
+  assert( pFile );
+  /* Check that one of SQLITE_SYNC_NORMAL or FULL was passed */
+  assert((flags&0x0F)==SQLITE_SYNC_NORMAL
+      || (flags&0x0F)==SQLITE_SYNC_FULL
+  );
+
+  /* Unix cannot, but some systems may return SQLITE_FULL from here. This
+  ** line is to test that doing so does not cause any problems.
+  */
+  SimulateDiskfullError( return SQLITE_FULL );
+
+  OSTRACE(("SYNC pid=%lu, pFile=%p, file=%p, flags=%x, lock=%d\n",
+           osGetCurrentProcessId(), pFile, pFile->h, flags,
+           pFile->locktype));
+
+#ifndef SQLITE_TEST
+  UNUSED_PARAMETER(flags);
+#else
+  if( (flags&0x0F)==SQLITE_SYNC_FULL ){
+    sqlite3_fullsync_count++;
+  }
+  sqlite3_sync_count++;
+#endif
+
+  /* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a
+  ** no-op
+  */
+#ifdef SQLITE_NO_SYNC
+  OSTRACE(("SYNC-NOP pid=%lu, pFile=%p, file=%p, rc=SQLITE_OK\n",
+           osGetCurrentProcessId(), pFile, pFile->h));
+  return SQLITE_OK;
+#else
+#if SQLITE_MAX_MMAP_SIZE>0
+  if( pFile->pMapRegion ){
+    if( osFlushViewOfFile(pFile->pMapRegion, 0) ){
+      OSTRACE(("SYNC-MMAP pid=%lu, pFile=%p, pMapRegion=%p, "
+               "rc=SQLITE_OK\n", osGetCurrentProcessId(),
+               pFile, pFile->pMapRegion));
+    }else{
+      pFile->lastErrno = osGetLastError();
+      OSTRACE(("SYNC-MMAP pid=%lu, pFile=%p, pMapRegion=%p, "
+               "rc=SQLITE_IOERR_MMAP\n", osGetCurrentProcessId(),
+               pFile, pFile->pMapRegion));
+      return winLogError(SQLITE_IOERR_MMAP, pFile->lastErrno,
+                         "winSync1", pFile->zPath);
+    }
+  }
+#endif
+  rc = osFlushFileBuffers(pFile->h);
+  SimulateIOError( rc=FALSE );
+  if( rc ){
+    OSTRACE(("SYNC pid=%lu, pFile=%p, file=%p, rc=SQLITE_OK\n",
+             osGetCurrentProcessId(), pFile, pFile->h));
+    return SQLITE_OK;
+  }else{
+    pFile->lastErrno = osGetLastError();
+    OSTRACE(("SYNC pid=%lu, pFile=%p, file=%p, rc=SQLITE_IOERR_FSYNC\n",
+             osGetCurrentProcessId(), pFile, pFile->h));
+    return winLogError(SQLITE_IOERR_FSYNC, pFile->lastErrno,
+                       "winSync2", pFile->zPath);
+  }
+#endif
+}
+
+/*
+** Determine the current size of a file in bytes
+*/
+static int winFileSize(sqlite3_file *id, sqlite3_int64 *pSize){
+  winFile *pFile = (winFile*)id;
+  int rc = SQLITE_OK;
+
+  assert( id!=0 );
+  assert( pSize!=0 );
+  SimulateIOError(return SQLITE_IOERR_FSTAT);
+  OSTRACE(("SIZE file=%p, pSize=%p\n", pFile->h, pSize));
+
+#if SQLITE_OS_WINRT
+  {
+    FILE_STANDARD_INFO info;
+    if( osGetFileInformationByHandleEx(pFile->h, FileStandardInfo,
+                                     &info, sizeof(info)) ){
+      *pSize = info.EndOfFile.QuadPart;
+    }else{
+      pFile->lastErrno = osGetLastError();
+      rc = winLogError(SQLITE_IOERR_FSTAT, pFile->lastErrno,
+                       "winFileSize", pFile->zPath);
+    }
+  }
+#else
+  {
+    DWORD upperBits;
+    DWORD lowerBits;
+    DWORD lastErrno;
+
+    lowerBits = osGetFileSize(pFile->h, &upperBits);
+    *pSize = (((sqlite3_int64)upperBits)<<32) + lowerBits;
+    if(   (lowerBits == INVALID_FILE_SIZE)
+       && ((lastErrno = osGetLastError())!=NO_ERROR) ){
+      pFile->lastErrno = lastErrno;
+      rc = winLogError(SQLITE_IOERR_FSTAT, pFile->lastErrno,
+                       "winFileSize", pFile->zPath);
+    }
+  }
+#endif
+  OSTRACE(("SIZE file=%p, pSize=%p, *pSize=%lld, rc=%s\n",
+           pFile->h, pSize, *pSize, sqlite3ErrName(rc)));
+  return rc;
+}
+
+/*
+** LOCKFILE_FAIL_IMMEDIATELY is undefined on some Windows systems.
+*/
+#ifndef LOCKFILE_FAIL_IMMEDIATELY
+# define LOCKFILE_FAIL_IMMEDIATELY 1
+#endif
+
+#ifndef LOCKFILE_EXCLUSIVE_LOCK
+# define LOCKFILE_EXCLUSIVE_LOCK 2
+#endif
+
+/*
+** Historically, SQLite has used both the LockFile and LockFileEx functions.
+** When the LockFile function was used, it was always expected to fail
+** immediately if the lock could not be obtained.  Also, it always expected to
+** obtain an exclusive lock.  These flags are used with the LockFileEx function
+** and reflect those expectations; therefore, they should not be changed.
+*/
+#ifndef SQLITE_LOCKFILE_FLAGS
+# define SQLITE_LOCKFILE_FLAGS   (LOCKFILE_FAIL_IMMEDIATELY | \
+                                  LOCKFILE_EXCLUSIVE_LOCK)
+#endif
+
+/*
+** Currently, SQLite never calls the LockFileEx function without wanting the
+** call to fail immediately if the lock cannot be obtained.
+*/
+#ifndef SQLITE_LOCKFILEEX_FLAGS
+# define SQLITE_LOCKFILEEX_FLAGS (LOCKFILE_FAIL_IMMEDIATELY)
+#endif
+
+/*
+** Acquire a reader lock.
+** Different API routines are called depending on whether or not this
+** is Win9x or WinNT.
+*/
+static int winGetReadLock(winFile *pFile){
+  int res;
+  OSTRACE(("READ-LOCK file=%p, lock=%d\n", pFile->h, pFile->locktype));
+  if( osIsNT() ){
+#if SQLITE_OS_WINCE
+    /*
+    ** NOTE: Windows CE is handled differently here due its lack of the Win32
+    **       API LockFileEx.
+    */
+    res = winceLockFile(&pFile->h, SHARED_FIRST, 0, 1, 0);
+#else
+    res = winLockFile(&pFile->h, SQLITE_LOCKFILEEX_FLAGS, SHARED_FIRST, 0,
+                      SHARED_SIZE, 0);
+#endif
+  }
+#ifdef SQLITE_WIN32_HAS_ANSI
+  else{
+    int lk;
+    sqlite3_randomness(sizeof(lk), &lk);
+    pFile->sharedLockByte = (short)((lk & 0x7fffffff)%(SHARED_SIZE - 1));
+    res = winLockFile(&pFile->h, SQLITE_LOCKFILE_FLAGS,
+                      SHARED_FIRST+pFile->sharedLockByte, 0, 1, 0);
+  }
+#endif
+  if( res == 0 ){
+    pFile->lastErrno = osGetLastError();
+    /* No need to log a failure to lock */
+  }
+  OSTRACE(("READ-LOCK file=%p, result=%d\n", pFile->h, res));
+  return res;
+}
+
+/*
+** Undo a readlock
+*/
+static int winUnlockReadLock(winFile *pFile){
+  int res;
+  DWORD lastErrno;
+  OSTRACE(("READ-UNLOCK file=%p, lock=%d\n", pFile->h, pFile->locktype));
+  if( osIsNT() ){
+    res = winUnlockFile(&pFile->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
+  }
+#ifdef SQLITE_WIN32_HAS_ANSI
+  else{
+    res = winUnlockFile(&pFile->h, SHARED_FIRST+pFile->sharedLockByte, 0, 1, 0);
+  }
+#endif
+  if( res==0 && ((lastErrno = osGetLastError())!=ERROR_NOT_LOCKED) ){
+    pFile->lastErrno = lastErrno;
+    winLogError(SQLITE_IOERR_UNLOCK, pFile->lastErrno,
+                "winUnlockReadLock", pFile->zPath);
+  }
+  OSTRACE(("READ-UNLOCK file=%p, result=%d\n", pFile->h, res));
+  return res;
+}
+
+/*
+** Lock the file with the lock specified by parameter locktype - one
+** of the following:
+**
+**     (1) SHARED_LOCK
+**     (2) RESERVED_LOCK
+**     (3) PENDING_LOCK
+**     (4) EXCLUSIVE_LOCK
+**
+** Sometimes when requesting one lock state, additional lock states
+** are inserted in between.  The locking might fail on one of the later
+** transitions leaving the lock state different from what it started but
+** still short of its goal.  The following chart shows the allowed
+** transitions and the inserted intermediate states:
+**
+**    UNLOCKED -> SHARED
+**    SHARED -> RESERVED
+**    SHARED -> (PENDING) -> EXCLUSIVE
+**    RESERVED -> (PENDING) -> EXCLUSIVE
+**    PENDING -> EXCLUSIVE
+**
+** This routine will only increase a lock.  The winUnlock() routine
+** erases all locks at once and returns us immediately to locking level 0.
+** It is not possible to lower the locking level one step at a time.  You
+** must go straight to locking level 0.
+*/
+static int winLock(sqlite3_file *id, int locktype){
+  int rc = SQLITE_OK;    /* Return code from subroutines */
+  int res = 1;           /* Result of a Windows lock call */
+  int newLocktype;       /* Set pFile->locktype to this value before exiting */
+  int gotPendingLock = 0;/* True if we acquired a PENDING lock this time */
+  winFile *pFile = (winFile*)id;
+  DWORD lastErrno = NO_ERROR;
+
+  assert( id!=0 );
+  OSTRACE(("LOCK file=%p, oldLock=%d(%d), newLock=%d\n",
+           pFile->h, pFile->locktype, pFile->sharedLockByte, locktype));
+
+  /* If there is already a lock of this type or more restrictive on the
+  ** OsFile, do nothing. Don't use the end_lock: exit path, as
+  ** sqlite3OsEnterMutex() hasn't been called yet.
+  */
+  if( pFile->locktype>=locktype ){
+    OSTRACE(("LOCK-HELD file=%p, rc=SQLITE_OK\n", pFile->h));
+    return SQLITE_OK;
+  }
+
+  /* Do not allow any kind of write-lock on a read-only database
+  */
+  if( (pFile->ctrlFlags & WINFILE_RDONLY)!=0 && locktype>=RESERVED_LOCK ){
+    return SQLITE_IOERR_LOCK;
+  }
+
+  /* Make sure the locking sequence is correct
+  */
+  assert( pFile->locktype!=NO_LOCK || locktype==SHARED_LOCK );
+  assert( locktype!=PENDING_LOCK );
+  assert( locktype!=RESERVED_LOCK || pFile->locktype==SHARED_LOCK );
+
+  /* Lock the PENDING_LOCK byte if we need to acquire a PENDING lock or
+  ** a SHARED lock.  If we are acquiring a SHARED lock, the acquisition of
+  ** the PENDING_LOCK byte is temporary.
+  */
+  newLocktype = pFile->locktype;
+  if( pFile->locktype==NO_LOCK
+   || (locktype==EXCLUSIVE_LOCK && pFile->locktype<=RESERVED_LOCK)
+  ){
+    int cnt = 3;
+    while( cnt-->0 && (res = winLockFile(&pFile->h, SQLITE_LOCKFILE_FLAGS,
+                                         PENDING_BYTE, 0, 1, 0))==0 ){
+      /* Try 3 times to get the pending lock.  This is needed to work
+      ** around problems caused by indexing and/or anti-virus software on
+      ** Windows systems.
+      ** If you are using this code as a model for alternative VFSes, do not
+      ** copy this retry logic.  It is a hack intended for Windows only.
+      */
+      lastErrno = osGetLastError();
+      OSTRACE(("LOCK-PENDING-FAIL file=%p, count=%d, result=%d\n",
+               pFile->h, cnt, res));
+      if( lastErrno==ERROR_INVALID_HANDLE ){
+        pFile->lastErrno = lastErrno;
+        rc = SQLITE_IOERR_LOCK;
+        OSTRACE(("LOCK-FAIL file=%p, count=%d, rc=%s\n",
+                 pFile->h, cnt, sqlite3ErrName(rc)));
+        return rc;
+      }
+      if( cnt ) sqlite3_win32_sleep(1);
+    }
+    gotPendingLock = res;
+    if( !res ){
+      lastErrno = osGetLastError();
+    }
+  }
+
+  /* Acquire a shared lock
+  */
+  if( locktype==SHARED_LOCK && res ){
+    assert( pFile->locktype==NO_LOCK );
+    res = winGetReadLock(pFile);
+    if( res ){
+      newLocktype = SHARED_LOCK;
+    }else{
+      lastErrno = osGetLastError();
+    }
+  }
+
+  /* Acquire a RESERVED lock
+  */
+  if( locktype==RESERVED_LOCK && res ){
+    assert( pFile->locktype==SHARED_LOCK );
+    res = winLockFile(&pFile->h, SQLITE_LOCKFILE_FLAGS, RESERVED_BYTE, 0, 1, 0);
+    if( res ){
+      newLocktype = RESERVED_LOCK;
+    }else{
+      lastErrno = osGetLastError();
+    }
+  }
+
+  /* Acquire a PENDING lock
+  */
+  if( locktype==EXCLUSIVE_LOCK && res ){
+    newLocktype = PENDING_LOCK;
+    gotPendingLock = 0;
+  }
+
+  /* Acquire an EXCLUSIVE lock
+  */
+  if( locktype==EXCLUSIVE_LOCK && res ){
+    assert( pFile->locktype>=SHARED_LOCK );
+    res = winUnlockReadLock(pFile);
+    res = winLockFile(&pFile->h, SQLITE_LOCKFILE_FLAGS, SHARED_FIRST, 0,
+                      SHARED_SIZE, 0);
+    if( res ){
+      newLocktype = EXCLUSIVE_LOCK;
+    }else{
+      lastErrno = osGetLastError();
+      winGetReadLock(pFile);
+    }
+  }
+
+  /* If we are holding a PENDING lock that ought to be released, then
+  ** release it now.
+  */
+  if( gotPendingLock && locktype==SHARED_LOCK ){
+    winUnlockFile(&pFile->h, PENDING_BYTE, 0, 1, 0);
+  }
+
+  /* Update the state of the lock has held in the file descriptor then
+  ** return the appropriate result code.
+  */
+  if( res ){
+    rc = SQLITE_OK;
+  }else{
+    pFile->lastErrno = lastErrno;
+    rc = SQLITE_BUSY;
+    OSTRACE(("LOCK-FAIL file=%p, wanted=%d, got=%d\n",
+             pFile->h, locktype, newLocktype));
+  }
+  pFile->locktype = (u8)newLocktype;
+  OSTRACE(("LOCK file=%p, lock=%d, rc=%s\n",
+           pFile->h, pFile->locktype, sqlite3ErrName(rc)));
+  return rc;
+}
+
+/*
+** This routine checks if there is a RESERVED lock held on the specified
+** file by this or any other process. If such a lock is held, return
+** non-zero, otherwise zero.
+*/
+static int winCheckReservedLock(sqlite3_file *id, int *pResOut){
+  int res;
+  winFile *pFile = (winFile*)id;
+
+  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
+  OSTRACE(("TEST-WR-LOCK file=%p, pResOut=%p\n", pFile->h, pResOut));
+
+  assert( id!=0 );
+  if( pFile->locktype>=RESERVED_LOCK ){
+    res = 1;
+    OSTRACE(("TEST-WR-LOCK file=%p, result=%d (local)\n", pFile->h, res));
+  }else{
+    res = winLockFile(&pFile->h, SQLITE_LOCKFILEEX_FLAGS,RESERVED_BYTE,0,1,0);
+    if( res ){
+      winUnlockFile(&pFile->h, RESERVED_BYTE, 0, 1, 0);
+    }
+    res = !res;
+    OSTRACE(("TEST-WR-LOCK file=%p, result=%d (remote)\n", pFile->h, res));
+  }
+  *pResOut = res;
+  OSTRACE(("TEST-WR-LOCK file=%p, pResOut=%p, *pResOut=%d, rc=SQLITE_OK\n",
+           pFile->h, pResOut, *pResOut));
+  return SQLITE_OK;
+}
+
+/*
+** Lower the locking level on file descriptor id to locktype.  locktype
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+**
+** It is not possible for this routine to fail if the second argument
+** is NO_LOCK.  If the second argument is SHARED_LOCK then this routine
+** might return SQLITE_IOERR;
+*/
+static int winUnlock(sqlite3_file *id, int locktype){
+  int type;
+  winFile *pFile = (winFile*)id;
+  int rc = SQLITE_OK;
+  assert( pFile!=0 );
+  assert( locktype<=SHARED_LOCK );
+  OSTRACE(("UNLOCK file=%p, oldLock=%d(%d), newLock=%d\n",
+           pFile->h, pFile->locktype, pFile->sharedLockByte, locktype));
+  type = pFile->locktype;
+  if( type>=EXCLUSIVE_LOCK ){
+    winUnlockFile(&pFile->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
+    if( locktype==SHARED_LOCK && !winGetReadLock(pFile) ){
+      /* This should never happen.  We should always be able to
+      ** reacquire the read lock */
+      rc = winLogError(SQLITE_IOERR_UNLOCK, osGetLastError(),
+                       "winUnlock", pFile->zPath);
+    }
+  }
+  if( type>=RESERVED_LOCK ){
+    winUnlockFile(&pFile->h, RESERVED_BYTE, 0, 1, 0);
+  }
+  if( locktype==NO_LOCK && type>=SHARED_LOCK ){
+    winUnlockReadLock(pFile);
+  }
+  if( type>=PENDING_LOCK ){
+    winUnlockFile(&pFile->h, PENDING_BYTE, 0, 1, 0);
+  }
+  pFile->locktype = (u8)locktype;
+  OSTRACE(("UNLOCK file=%p, lock=%d, rc=%s\n",
+           pFile->h, pFile->locktype, sqlite3ErrName(rc)));
+  return rc;
+}
+
+/******************************************************************************
+****************************** No-op Locking **********************************
+**
+** Of the various locking implementations available, this is by far the
+** simplest:  locking is ignored.  No attempt is made to lock the database
+** file for reading or writing.
+**
+** This locking mode is appropriate for use on read-only databases
+** (ex: databases that are burned into CD-ROM, for example.)  It can
+** also be used if the application employs some external mechanism to
+** prevent simultaneous access of the same database by two or more
+** database connections.  But there is a serious risk of database
+** corruption if this locking mode is used in situations where multiple
+** database connections are accessing the same database file at the same
+** time and one or more of those connections are writing.
+*/
+
+static int winNolockLock(sqlite3_file *id, int locktype){
+  UNUSED_PARAMETER(id);
+  UNUSED_PARAMETER(locktype);
+  return SQLITE_OK;
+}
+
+static int winNolockCheckReservedLock(sqlite3_file *id, int *pResOut){
+  UNUSED_PARAMETER(id);
+  UNUSED_PARAMETER(pResOut);
+  return SQLITE_OK;
+}
+
+static int winNolockUnlock(sqlite3_file *id, int locktype){
+  UNUSED_PARAMETER(id);
+  UNUSED_PARAMETER(locktype);
+  return SQLITE_OK;
+}
+
+/******************* End of the no-op lock implementation *********************
+******************************************************************************/
+
+/*
+** If *pArg is initially negative then this is a query.  Set *pArg to
+** 1 or 0 depending on whether or not bit mask of pFile->ctrlFlags is set.
+**
+** If *pArg is 0 or 1, then clear or set the mask bit of pFile->ctrlFlags.
+*/
+static void winModeBit(winFile *pFile, unsigned char mask, int *pArg){
+  if( *pArg<0 ){
+    *pArg = (pFile->ctrlFlags & mask)!=0;
+  }else if( (*pArg)==0 ){
+    pFile->ctrlFlags &= ~mask;
+  }else{
+    pFile->ctrlFlags |= mask;
+  }
+}
+
+/* Forward references to VFS helper methods used for temporary files */
+static int winGetTempname(sqlite3_vfs *, char **);
+static int winIsDir(const void *);
+static BOOL winIsDriveLetterAndColon(const char *);
+
+/*
+** Control and query of the open file handle.
+*/
+static int winFileControl(sqlite3_file *id, int op, void *pArg){
+  winFile *pFile = (winFile*)id;
+  OSTRACE(("FCNTL file=%p, op=%d, pArg=%p\n", pFile->h, op, pArg));
+  switch( op ){
+    case SQLITE_FCNTL_LOCKSTATE: {
+      *(int*)pArg = pFile->locktype;
+      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_LAST_ERRNO: {
+      *(int*)pArg = (int)pFile->lastErrno;
+      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_CHUNK_SIZE: {
+      pFile->szChunk = *(int *)pArg;
+      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_SIZE_HINT: {
+      if( pFile->szChunk>0 ){
+        sqlite3_int64 oldSz;
+        int rc = winFileSize(id, &oldSz);
+        if( rc==SQLITE_OK ){
+          sqlite3_int64 newSz = *(sqlite3_int64*)pArg;
+          if( newSz>oldSz ){
+            SimulateIOErrorBenign(1);
+            rc = winTruncate(id, newSz);
+            SimulateIOErrorBenign(0);
+          }
+        }
+        OSTRACE(("FCNTL file=%p, rc=%s\n", pFile->h, sqlite3ErrName(rc)));
+        return rc;
+      }
+      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_PERSIST_WAL: {
+      winModeBit(pFile, WINFILE_PERSIST_WAL, (int*)pArg);
+      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_POWERSAFE_OVERWRITE: {
+      winModeBit(pFile, WINFILE_PSOW, (int*)pArg);
+      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_VFSNAME: {
+      *(char**)pArg = sqlite3_mprintf("%s", pFile->pVfs->zName);
+      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_WIN32_AV_RETRY: {
+      int *a = (int*)pArg;
+      if( a[0]>0 ){
+        winIoerrRetry = a[0];
+      }else{
+        a[0] = winIoerrRetry;
+      }
+      if( a[1]>0 ){
+        winIoerrRetryDelay = a[1];
+      }else{
+        a[1] = winIoerrRetryDelay;
+      }
+      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_WIN32_GET_HANDLE: {
+      LPHANDLE phFile = (LPHANDLE)pArg;
+      *phFile = pFile->h;
+      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
+      return SQLITE_OK;
+    }
+#ifdef SQLITE_TEST
+    case SQLITE_FCNTL_WIN32_SET_HANDLE: {
+      LPHANDLE phFile = (LPHANDLE)pArg;
+      HANDLE hOldFile = pFile->h;
+      pFile->h = *phFile;
+      *phFile = hOldFile;
+      OSTRACE(("FCNTL oldFile=%p, newFile=%p, rc=SQLITE_OK\n",
+               hOldFile, pFile->h));
+      return SQLITE_OK;
+    }
+#endif
+    case SQLITE_FCNTL_TEMPFILENAME: {
+      char *zTFile = 0;
+      int rc = winGetTempname(pFile->pVfs, &zTFile);
+      if( rc==SQLITE_OK ){
+        *(char**)pArg = zTFile;
+      }
+      OSTRACE(("FCNTL file=%p, rc=%s\n", pFile->h, sqlite3ErrName(rc)));
+      return rc;
+    }
+#if SQLITE_MAX_MMAP_SIZE>0
+    case SQLITE_FCNTL_MMAP_SIZE: {
+      i64 newLimit = *(i64*)pArg;
+      int rc = SQLITE_OK;
+      if( newLimit>sqlite3GlobalConfig.mxMmap ){
+        newLimit = sqlite3GlobalConfig.mxMmap;
+      }
+      *(i64*)pArg = pFile->mmapSizeMax;
+      if( newLimit>=0 && newLimit!=pFile->mmapSizeMax && pFile->nFetchOut==0 ){
+        pFile->mmapSizeMax = newLimit;
+        if( pFile->mmapSize>0 ){
+          winUnmapfile(pFile);
+          rc = winMapfile(pFile, -1);
+        }
+      }
+      OSTRACE(("FCNTL file=%p, rc=%s\n", pFile->h, sqlite3ErrName(rc)));
+      return rc;
+    }
+#endif
+  }
+  OSTRACE(("FCNTL file=%p, rc=SQLITE_NOTFOUND\n", pFile->h));
+  return SQLITE_NOTFOUND;
+}
+
+/*
+** Return the sector size in bytes of the underlying block device for
+** the specified file. This is almost always 512 bytes, but may be
+** larger for some devices.
+**
+** SQLite code assumes this function cannot fail. It also assumes that
+** if two files are created in the same file-system directory (i.e.
+** a database and its journal file) that the sector size will be the
+** same for both.
+*/
+static int winSectorSize(sqlite3_file *id){
+  (void)id;
+  return SQLITE_DEFAULT_SECTOR_SIZE;
+}
+
+/*
+** Return a vector of device characteristics.
+*/
+static int winDeviceCharacteristics(sqlite3_file *id){
+  winFile *p = (winFile*)id;
+  return SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN |
+         ((p->ctrlFlags & WINFILE_PSOW)?SQLITE_IOCAP_POWERSAFE_OVERWRITE:0);
+}
+
+/*
+** Windows will only let you create file view mappings
+** on allocation size granularity boundaries.
+** During sqlite3_os_init() we do a GetSystemInfo()
+** to get the granularity size.
+*/
+static SYSTEM_INFO winSysInfo;
+
+#ifndef SQLITE_OMIT_WAL
+
+/*
+** Helper functions to obtain and relinquish the global mutex. The
+** global mutex is used to protect the winLockInfo objects used by
+** this file, all of which may be shared by multiple threads.
+**
+** Function winShmMutexHeld() is used to assert() that the global mutex
+** is held when required. This function is only used as part of assert()
+** statements. e.g.
+**
+**   winShmEnterMutex()
+**     assert( winShmMutexHeld() );
+**   winShmLeaveMutex()
+*/
+static void winShmEnterMutex(void){
+  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_VFS1));
+}
+static void winShmLeaveMutex(void){
+  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_VFS1));
+}
+#ifndef NDEBUG
+static int winShmMutexHeld(void) {
+  return sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_VFS1));
+}
+#endif
+
+/*
+** Object used to represent a single file opened and mmapped to provide
+** shared memory.  When multiple threads all reference the same
+** log-summary, each thread has its own winFile object, but they all
+** point to a single instance of this object.  In other words, each
+** log-summary is opened only once per process.
+**
+** winShmMutexHeld() must be true when creating or destroying
+** this object or while reading or writing the following fields:
+**
+**      nRef
+**      pNext
+**
+** The following fields are read-only after the object is created:
+**
+**      fid
+**      zFilename
+**
+** Either winShmNode.mutex must be held or winShmNode.nRef==0 and
+** winShmMutexHeld() is true when reading or writing any other field
+** in this structure.
+**
+*/
+struct winShmNode {
+  sqlite3_mutex *mutex;      /* Mutex to access this object */
+  char *zFilename;           /* Name of the file */
+  winFile hFile;             /* File handle from winOpen */
+
+  int szRegion;              /* Size of shared-memory regions */
+  int nRegion;               /* Size of array apRegion */
+  struct ShmRegion {
+    HANDLE hMap;             /* File handle from CreateFileMapping */
+    void *pMap;
+  } *aRegion;
+  DWORD lastErrno;           /* The Windows errno from the last I/O error */
+
+  int nRef;                  /* Number of winShm objects pointing to this */
+  winShm *pFirst;            /* All winShm objects pointing to this */
+  winShmNode *pNext;         /* Next in list of all winShmNode objects */
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
+  u8 nextShmId;              /* Next available winShm.id value */
+#endif
+};
+
+/*
+** A global array of all winShmNode objects.
+**
+** The winShmMutexHeld() must be true while reading or writing this list.
+*/
+static winShmNode *winShmNodeList = 0;
+
+/*
+** Structure used internally by this VFS to record the state of an
+** open shared memory connection.
+**
+** The following fields are initialized when this object is created and
+** are read-only thereafter:
+**
+**    winShm.pShmNode
+**    winShm.id
+**
+** All other fields are read/write.  The winShm.pShmNode->mutex must be held
+** while accessing any read/write fields.
+*/
+struct winShm {
+  winShmNode *pShmNode;      /* The underlying winShmNode object */
+  winShm *pNext;             /* Next winShm with the same winShmNode */
+  u8 hasMutex;               /* True if holding the winShmNode mutex */
+  u16 sharedMask;            /* Mask of shared locks held */
+  u16 exclMask;              /* Mask of exclusive locks held */
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
+  u8 id;                     /* Id of this connection with its winShmNode */
+#endif
+};
+
+/*
+** Constants used for locking
+*/
+#define WIN_SHM_BASE   ((22+SQLITE_SHM_NLOCK)*4)        /* first lock byte */
+#define WIN_SHM_DMS    (WIN_SHM_BASE+SQLITE_SHM_NLOCK)  /* deadman switch */
+
+/*
+** Apply advisory locks for all n bytes beginning at ofst.
+*/
+#define WINSHM_UNLCK  1
+#define WINSHM_RDLCK  2
+#define WINSHM_WRLCK  3
+static int winShmSystemLock(
+  winShmNode *pFile,    /* Apply locks to this open shared-memory segment */
+  int lockType,         /* WINSHM_UNLCK, WINSHM_RDLCK, or WINSHM_WRLCK */
+  int ofst,             /* Offset to first byte to be locked/unlocked */
+  int nByte             /* Number of bytes to lock or unlock */
+){
+  int rc = 0;           /* Result code form Lock/UnlockFileEx() */
+
+  /* Access to the winShmNode object is serialized by the caller */
+  assert( sqlite3_mutex_held(pFile->mutex) || pFile->nRef==0 );
+
+  OSTRACE(("SHM-LOCK file=%p, lock=%d, offset=%d, size=%d\n",
+           pFile->hFile.h, lockType, ofst, nByte));
+
+  /* Release/Acquire the system-level lock */
+  if( lockType==WINSHM_UNLCK ){
+    rc = winUnlockFile(&pFile->hFile.h, ofst, 0, nByte, 0);
+  }else{
+    /* Initialize the locking parameters */
+    DWORD dwFlags = LOCKFILE_FAIL_IMMEDIATELY;
+    if( lockType == WINSHM_WRLCK ) dwFlags |= LOCKFILE_EXCLUSIVE_LOCK;
+    rc = winLockFile(&pFile->hFile.h, dwFlags, ofst, 0, nByte, 0);
+  }
+
+  if( rc!= 0 ){
+    rc = SQLITE_OK;
+  }else{
+    pFile->lastErrno =  osGetLastError();
+    rc = SQLITE_BUSY;
+  }
+
+  OSTRACE(("SHM-LOCK file=%p, func=%s, errno=%lu, rc=%s\n",
+           pFile->hFile.h, (lockType == WINSHM_UNLCK) ? "winUnlockFile" :
+           "winLockFile", pFile->lastErrno, sqlite3ErrName(rc)));
+
+  return rc;
+}
+
+/* Forward references to VFS methods */
+static int winOpen(sqlite3_vfs*,const char*,sqlite3_file*,int,int*);
+static int winDelete(sqlite3_vfs *,const char*,int);
+
+/*
+** Purge the winShmNodeList list of all entries with winShmNode.nRef==0.
+**
+** This is not a VFS shared-memory method; it is a utility function called
+** by VFS shared-memory methods.
+*/
+static void winShmPurge(sqlite3_vfs *pVfs, int deleteFlag){
+  winShmNode **pp;
+  winShmNode *p;
+  assert( winShmMutexHeld() );
+  OSTRACE(("SHM-PURGE pid=%lu, deleteFlag=%d\n",
+           osGetCurrentProcessId(), deleteFlag));
+  pp = &winShmNodeList;
+  while( (p = *pp)!=0 ){
+    if( p->nRef==0 ){
+      int i;
+      if( p->mutex ){ sqlite3_mutex_free(p->mutex); }
+      for(i=0; i<p->nRegion; i++){
+        BOOL bRc = osUnmapViewOfFile(p->aRegion[i].pMap);
+        OSTRACE(("SHM-PURGE-UNMAP pid=%lu, region=%d, rc=%s\n",
+                 osGetCurrentProcessId(), i, bRc ? "ok" : "failed"));
+        UNUSED_VARIABLE_VALUE(bRc);
+        bRc = osCloseHandle(p->aRegion[i].hMap);
+        OSTRACE(("SHM-PURGE-CLOSE pid=%lu, region=%d, rc=%s\n",
+                 osGetCurrentProcessId(), i, bRc ? "ok" : "failed"));
+        UNUSED_VARIABLE_VALUE(bRc);
+      }
+      if( p->hFile.h!=NULL && p->hFile.h!=INVALID_HANDLE_VALUE ){
+        SimulateIOErrorBenign(1);
+        winClose((sqlite3_file *)&p->hFile);
+        SimulateIOErrorBenign(0);
+      }
+      if( deleteFlag ){
+        SimulateIOErrorBenign(1);
+        sqlite3BeginBenignMalloc();
+        winDelete(pVfs, p->zFilename, 0);
+        sqlite3EndBenignMalloc();
+        SimulateIOErrorBenign(0);
+      }
+      *pp = p->pNext;
+      sqlite3_free(p->aRegion);
+      sqlite3_free(p);
+    }else{
+      pp = &p->pNext;
+    }
+  }
+}
+
+/*
+** Open the shared-memory area associated with database file pDbFd.
+**
+** When opening a new shared-memory file, if no other instances of that
+** file are currently open, in this process or in other processes, then
+** the file must be truncated to zero length or have its header cleared.
+*/
+static int winOpenSharedMemory(winFile *pDbFd){
+  struct winShm *p;                  /* The connection to be opened */
+  struct winShmNode *pShmNode = 0;   /* The underlying mmapped file */
+  int rc;                            /* Result code */
+  struct winShmNode *pNew;           /* Newly allocated winShmNode */
+  int nName;                         /* Size of zName in bytes */
+
+  assert( pDbFd->pShm==0 );    /* Not previously opened */
+
+  /* Allocate space for the new sqlite3_shm object.  Also speculatively
+  ** allocate space for a new winShmNode and filename.
+  */
+  p = sqlite3MallocZero( sizeof(*p) );
+  if( p==0 ) return SQLITE_IOERR_NOMEM_BKPT;
+  nName = sqlite3Strlen30(pDbFd->zPath);
+  pNew = sqlite3MallocZero( sizeof(*pShmNode) + nName + 17 );
+  if( pNew==0 ){
+    sqlite3_free(p);
+    return SQLITE_IOERR_NOMEM_BKPT;
+  }
+  pNew->zFilename = (char*)&pNew[1];
+  sqlite3_snprintf(nName+15, pNew->zFilename, "%s-shm", pDbFd->zPath);
+  sqlite3FileSuffix3(pDbFd->zPath, pNew->zFilename);
+
+  /* Look to see if there is an existing winShmNode that can be used.
+  ** If no matching winShmNode currently exists, create a new one.
+  */
+  winShmEnterMutex();
+  for(pShmNode = winShmNodeList; pShmNode; pShmNode=pShmNode->pNext){
+    /* TBD need to come up with better match here.  Perhaps
+    ** use FILE_ID_BOTH_DIR_INFO Structure.
+    */
+    if( sqlite3StrICmp(pShmNode->zFilename, pNew->zFilename)==0 ) break;
+  }
+  if( pShmNode ){
+    sqlite3_free(pNew);
+  }else{
+    pShmNode = pNew;
+    pNew = 0;
+    ((winFile*)(&pShmNode->hFile))->h = INVALID_HANDLE_VALUE;
+    pShmNode->pNext = winShmNodeList;
+    winShmNodeList = pShmNode;
+
+    if( sqlite3GlobalConfig.bCoreMutex ){
+      pShmNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
+      if( pShmNode->mutex==0 ){
+        rc = SQLITE_IOERR_NOMEM_BKPT;
+        goto shm_open_err;
+      }
+    }
+
+    rc = winOpen(pDbFd->pVfs,
+                 pShmNode->zFilename,             /* Name of the file (UTF-8) */
+                 (sqlite3_file*)&pShmNode->hFile,  /* File handle here */
+                 SQLITE_OPEN_WAL | SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE,
+                 0);
+    if( SQLITE_OK!=rc ){
+      goto shm_open_err;
+    }
+
+    /* Check to see if another process is holding the dead-man switch.
+    ** If not, truncate the file to zero length.
+    */
+    if( winShmSystemLock(pShmNode, WINSHM_WRLCK, WIN_SHM_DMS, 1)==SQLITE_OK ){
+      rc = winTruncate((sqlite3_file *)&pShmNode->hFile, 0);
+      if( rc!=SQLITE_OK ){
+        rc = winLogError(SQLITE_IOERR_SHMOPEN, osGetLastError(),
+                         "winOpenShm", pDbFd->zPath);
+      }
+    }
+    if( rc==SQLITE_OK ){
+      winShmSystemLock(pShmNode, WINSHM_UNLCK, WIN_SHM_DMS, 1);
+      rc = winShmSystemLock(pShmNode, WINSHM_RDLCK, WIN_SHM_DMS, 1);
+    }
+    if( rc ) goto shm_open_err;
+  }
+
+  /* Make the new connection a child of the winShmNode */
+  p->pShmNode = pShmNode;
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
+  p->id = pShmNode->nextShmId++;
+#endif
+  pShmNode->nRef++;
+  pDbFd->pShm = p;
+  winShmLeaveMutex();
+
+  /* The reference count on pShmNode has already been incremented under
+  ** the cover of the winShmEnterMutex() mutex and the pointer from the
+  ** new (struct winShm) object to the pShmNode has been set. All that is
+  ** left to do is to link the new object into the linked list starting
+  ** at pShmNode->pFirst. This must be done while holding the pShmNode->mutex
+  ** mutex.
+  */
+  sqlite3_mutex_enter(pShmNode->mutex);
+  p->pNext = pShmNode->pFirst;
+  pShmNode->pFirst = p;
+  sqlite3_mutex_leave(pShmNode->mutex);
+  return SQLITE_OK;
+
+  /* Jump here on any error */
+shm_open_err:
+  winShmSystemLock(pShmNode, WINSHM_UNLCK, WIN_SHM_DMS, 1);
+  winShmPurge(pDbFd->pVfs, 0);      /* This call frees pShmNode if required */
+  sqlite3_free(p);
+  sqlite3_free(pNew);
+  winShmLeaveMutex();
+  return rc;
+}
+
+/*
+** Close a connection to shared-memory.  Delete the underlying
+** storage if deleteFlag is true.
+*/
+static int winShmUnmap(
+  sqlite3_file *fd,          /* Database holding shared memory */
+  int deleteFlag             /* Delete after closing if true */
+){
+  winFile *pDbFd;       /* Database holding shared-memory */
+  winShm *p;            /* The connection to be closed */
+  winShmNode *pShmNode; /* The underlying shared-memory file */
+  winShm **pp;          /* For looping over sibling connections */
+
+  pDbFd = (winFile*)fd;
+  p = pDbFd->pShm;
+  if( p==0 ) return SQLITE_OK;
+  pShmNode = p->pShmNode;
+
+  /* Remove connection p from the set of connections associated
+  ** with pShmNode */
+  sqlite3_mutex_enter(pShmNode->mutex);
+  for(pp=&pShmNode->pFirst; (*pp)!=p; pp = &(*pp)->pNext){}
+  *pp = p->pNext;
+
+  /* Free the connection p */
+  sqlite3_free(p);
+  pDbFd->pShm = 0;
+  sqlite3_mutex_leave(pShmNode->mutex);
+
+  /* If pShmNode->nRef has reached 0, then close the underlying
+  ** shared-memory file, too */
+  winShmEnterMutex();
+  assert( pShmNode->nRef>0 );
+  pShmNode->nRef--;
+  if( pShmNode->nRef==0 ){
+    winShmPurge(pDbFd->pVfs, deleteFlag);
+  }
+  winShmLeaveMutex();
+
+  return SQLITE_OK;
+}
+
+/*
+** Change the lock state for a shared-memory segment.
+*/
+static int winShmLock(
+  sqlite3_file *fd,          /* Database file holding the shared memory */
+  int ofst,                  /* First lock to acquire or release */
+  int n,                     /* Number of locks to acquire or release */
+  int flags                  /* What to do with the lock */
+){
+  winFile *pDbFd = (winFile*)fd;        /* Connection holding shared memory */
+  winShm *p = pDbFd->pShm;              /* The shared memory being locked */
+  winShm *pX;                           /* For looping over all siblings */
+  winShmNode *pShmNode = p->pShmNode;
+  int rc = SQLITE_OK;                   /* Result code */
+  u16 mask;                             /* Mask of locks to take or release */
+
+  assert( ofst>=0 && ofst+n<=SQLITE_SHM_NLOCK );
+  assert( n>=1 );
+  assert( flags==(SQLITE_SHM_LOCK | SQLITE_SHM_SHARED)
+       || flags==(SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE)
+       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED)
+       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) );
+  assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 );
+
+  mask = (u16)((1U<<(ofst+n)) - (1U<<ofst));
+  assert( n>1 || mask==(1<<ofst) );
+  sqlite3_mutex_enter(pShmNode->mutex);
+  if( flags & SQLITE_SHM_UNLOCK ){
+    u16 allMask = 0; /* Mask of locks held by siblings */
+
+    /* See if any siblings hold this same lock */
+    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
+      if( pX==p ) continue;
+      assert( (pX->exclMask & (p->exclMask|p->sharedMask))==0 );
+      allMask |= pX->sharedMask;
+    }
+
+    /* Unlock the system-level locks */
+    if( (mask & allMask)==0 ){
+      rc = winShmSystemLock(pShmNode, WINSHM_UNLCK, ofst+WIN_SHM_BASE, n);
+    }else{
+      rc = SQLITE_OK;
+    }
+
+    /* Undo the local locks */
+    if( rc==SQLITE_OK ){
+      p->exclMask &= ~mask;
+      p->sharedMask &= ~mask;
+    }
+  }else if( flags & SQLITE_SHM_SHARED ){
+    u16 allShared = 0;  /* Union of locks held by connections other than "p" */
+
+    /* Find out which shared locks are already held by sibling connections.
+    ** If any sibling already holds an exclusive lock, go ahead and return
+    ** SQLITE_BUSY.
+    */
+    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
+      if( (pX->exclMask & mask)!=0 ){
+        rc = SQLITE_BUSY;
+        break;
+      }
+      allShared |= pX->sharedMask;
+    }
+
+    /* Get shared locks at the system level, if necessary */
+    if( rc==SQLITE_OK ){
+      if( (allShared & mask)==0 ){
+        rc = winShmSystemLock(pShmNode, WINSHM_RDLCK, ofst+WIN_SHM_BASE, n);
+      }else{
+        rc = SQLITE_OK;
+      }
+    }
+
+    /* Get the local shared locks */
+    if( rc==SQLITE_OK ){
+      p->sharedMask |= mask;
+    }
+  }else{
+    /* Make sure no sibling connections hold locks that will block this
+    ** lock.  If any do, return SQLITE_BUSY right away.
+    */
+    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
+      if( (pX->exclMask & mask)!=0 || (pX->sharedMask & mask)!=0 ){
+        rc = SQLITE_BUSY;
+        break;
+      }
+    }
+
+    /* Get the exclusive locks at the system level.  Then if successful
+    ** also mark the local connection as being locked.
+    */
+    if( rc==SQLITE_OK ){
+      rc = winShmSystemLock(pShmNode, WINSHM_WRLCK, ofst+WIN_SHM_BASE, n);
+      if( rc==SQLITE_OK ){
+        assert( (p->sharedMask & mask)==0 );
+        p->exclMask |= mask;
+      }
+    }
+  }
+  sqlite3_mutex_leave(pShmNode->mutex);
+  OSTRACE(("SHM-LOCK pid=%lu, id=%d, sharedMask=%03x, exclMask=%03x, rc=%s\n",
+           osGetCurrentProcessId(), p->id, p->sharedMask, p->exclMask,
+           sqlite3ErrName(rc)));
+  return rc;
+}
+
+/*
+** Implement a memory barrier or memory fence on shared memory.
+**
+** All loads and stores begun before the barrier must complete before
+** any load or store begun after the barrier.
+*/
+static void winShmBarrier(
+  sqlite3_file *fd          /* Database holding the shared memory */
+){
+  UNUSED_PARAMETER(fd);
+  sqlite3MemoryBarrier();   /* compiler-defined memory barrier */
+  winShmEnterMutex();       /* Also mutex, for redundancy */
+  winShmLeaveMutex();
+}
+
+/*
+** This function is called to obtain a pointer to region iRegion of the
+** shared-memory associated with the database file fd. Shared-memory regions
+** are numbered starting from zero. Each shared-memory region is szRegion
+** bytes in size.
+**
+** If an error occurs, an error code is returned and *pp is set to NULL.
+**
+** Otherwise, if the isWrite parameter is 0 and the requested shared-memory
+** region has not been allocated (by any client, including one running in a
+** separate process), then *pp is set to NULL and SQLITE_OK returned. If
+** isWrite is non-zero and the requested shared-memory region has not yet
+** been allocated, it is allocated by this function.
+**
+** If the shared-memory region has already been allocated or is allocated by
+** this call as described above, then it is mapped into this processes
+** address space (if it is not already), *pp is set to point to the mapped
+** memory and SQLITE_OK returned.
+*/
+static int winShmMap(
+  sqlite3_file *fd,               /* Handle open on database file */
+  int iRegion,                    /* Region to retrieve */
+  int szRegion,                   /* Size of regions */
+  int isWrite,                    /* True to extend file if necessary */
+  void volatile **pp              /* OUT: Mapped memory */
+){
+  winFile *pDbFd = (winFile*)fd;
+  winShm *pShm = pDbFd->pShm;
+  winShmNode *pShmNode;
+  int rc = SQLITE_OK;
+
+  if( !pShm ){
+    rc = winOpenSharedMemory(pDbFd);
+    if( rc!=SQLITE_OK ) return rc;
+    pShm = pDbFd->pShm;
+  }
+  pShmNode = pShm->pShmNode;
+
+  sqlite3_mutex_enter(pShmNode->mutex);
+  assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 );
+
+  if( pShmNode->nRegion<=iRegion ){
+    struct ShmRegion *apNew;           /* New aRegion[] array */
+    int nByte = (iRegion+1)*szRegion;  /* Minimum required file size */
+    sqlite3_int64 sz;                  /* Current size of wal-index file */
+
+    pShmNode->szRegion = szRegion;
+
+    /* The requested region is not mapped into this processes address space.
+    ** Check to see if it has been allocated (i.e. if the wal-index file is
+    ** large enough to contain the requested region).
+    */
+    rc = winFileSize((sqlite3_file *)&pShmNode->hFile, &sz);
+    if( rc!=SQLITE_OK ){
+      rc = winLogError(SQLITE_IOERR_SHMSIZE, osGetLastError(),
+                       "winShmMap1", pDbFd->zPath);
+      goto shmpage_out;
+    }
+
+    if( sz<nByte ){
+      /* The requested memory region does not exist. If isWrite is set to
+      ** zero, exit early. *pp will be set to NULL and SQLITE_OK returned.
+      **
+      ** Alternatively, if isWrite is non-zero, use ftruncate() to allocate
+      ** the requested memory region.
+      */
+      if( !isWrite ) goto shmpage_out;
+      rc = winTruncate((sqlite3_file *)&pShmNode->hFile, nByte);
+      if( rc!=SQLITE_OK ){
+        rc = winLogError(SQLITE_IOERR_SHMSIZE, osGetLastError(),
+                         "winShmMap2", pDbFd->zPath);
+        goto shmpage_out;
+      }
+    }
+
+    /* Map the requested memory region into this processes address space. */
+    apNew = (struct ShmRegion *)sqlite3_realloc64(
+        pShmNode->aRegion, (iRegion+1)*sizeof(apNew[0])
+    );
+    if( !apNew ){
+      rc = SQLITE_IOERR_NOMEM_BKPT;
+      goto shmpage_out;
+    }
+    pShmNode->aRegion = apNew;
+
+    while( pShmNode->nRegion<=iRegion ){
+      HANDLE hMap = NULL;         /* file-mapping handle */
+      void *pMap = 0;             /* Mapped memory region */
+
+#if SQLITE_OS_WINRT
+      hMap = osCreateFileMappingFromApp(pShmNode->hFile.h,
+          NULL, PAGE_READWRITE, nByte, NULL
+      );
+#elif defined(SQLITE_WIN32_HAS_WIDE)
+      hMap = osCreateFileMappingW(pShmNode->hFile.h,
+          NULL, PAGE_READWRITE, 0, nByte, NULL
+      );
+#elif defined(SQLITE_WIN32_HAS_ANSI) && SQLITE_WIN32_CREATEFILEMAPPINGA
+      hMap = osCreateFileMappingA(pShmNode->hFile.h,
+          NULL, PAGE_READWRITE, 0, nByte, NULL
+      );
+#endif
+      OSTRACE(("SHM-MAP-CREATE pid=%lu, region=%d, size=%d, rc=%s\n",
+               osGetCurrentProcessId(), pShmNode->nRegion, nByte,
+               hMap ? "ok" : "failed"));
+      if( hMap ){
+        int iOffset = pShmNode->nRegion*szRegion;
+        int iOffsetShift = iOffset % winSysInfo.dwAllocationGranularity;
+#if SQLITE_OS_WINRT
+        pMap = osMapViewOfFileFromApp(hMap, FILE_MAP_WRITE | FILE_MAP_READ,
+            iOffset - iOffsetShift, szRegion + iOffsetShift
+        );
+#else
+        pMap = osMapViewOfFile(hMap, FILE_MAP_WRITE | FILE_MAP_READ,
+            0, iOffset - iOffsetShift, szRegion + iOffsetShift
+        );
+#endif
+        OSTRACE(("SHM-MAP-MAP pid=%lu, region=%d, offset=%d, size=%d, rc=%s\n",
+                 osGetCurrentProcessId(), pShmNode->nRegion, iOffset,
+                 szRegion, pMap ? "ok" : "failed"));
+      }
+      if( !pMap ){
+        pShmNode->lastErrno = osGetLastError();
+        rc = winLogError(SQLITE_IOERR_SHMMAP, pShmNode->lastErrno,
+                         "winShmMap3", pDbFd->zPath);
+        if( hMap ) osCloseHandle(hMap);
+        goto shmpage_out;
+      }
+
+      pShmNode->aRegion[pShmNode->nRegion].pMap = pMap;
+      pShmNode->aRegion[pShmNode->nRegion].hMap = hMap;
+      pShmNode->nRegion++;
+    }
+  }
+
+shmpage_out:
+  if( pShmNode->nRegion>iRegion ){
+    int iOffset = iRegion*szRegion;
+    int iOffsetShift = iOffset % winSysInfo.dwAllocationGranularity;
+    char *p = (char *)pShmNode->aRegion[iRegion].pMap;
+    *pp = (void *)&p[iOffsetShift];
+  }else{
+    *pp = 0;
+  }
+  sqlite3_mutex_leave(pShmNode->mutex);
+  return rc;
+}
+
+#else
+# define winShmMap     0
+# define winShmLock    0
+# define winShmBarrier 0
+# define winShmUnmap   0
+#endif /* #ifndef SQLITE_OMIT_WAL */
+
+/*
+** Cleans up the mapped region of the specified file, if any.
+*/
+#if SQLITE_MAX_MMAP_SIZE>0
+static int winUnmapfile(winFile *pFile){
+  assert( pFile!=0 );
+  OSTRACE(("UNMAP-FILE pid=%lu, pFile=%p, hMap=%p, pMapRegion=%p, "
+           "mmapSize=%lld, mmapSizeActual=%lld, mmapSizeMax=%lld\n",
+           osGetCurrentProcessId(), pFile, pFile->hMap, pFile->pMapRegion,
+           pFile->mmapSize, pFile->mmapSizeActual, pFile->mmapSizeMax));
+  if( pFile->pMapRegion ){
+    if( !osUnmapViewOfFile(pFile->pMapRegion) ){
+      pFile->lastErrno = osGetLastError();
+      OSTRACE(("UNMAP-FILE pid=%lu, pFile=%p, pMapRegion=%p, "
+               "rc=SQLITE_IOERR_MMAP\n", osGetCurrentProcessId(), pFile,
+               pFile->pMapRegion));
+      return winLogError(SQLITE_IOERR_MMAP, pFile->lastErrno,
+                         "winUnmapfile1", pFile->zPath);
+    }
+    pFile->pMapRegion = 0;
+    pFile->mmapSize = 0;
+    pFile->mmapSizeActual = 0;
+  }
+  if( pFile->hMap!=NULL ){
+    if( !osCloseHandle(pFile->hMap) ){
+      pFile->lastErrno = osGetLastError();
+      OSTRACE(("UNMAP-FILE pid=%lu, pFile=%p, hMap=%p, rc=SQLITE_IOERR_MMAP\n",
+               osGetCurrentProcessId(), pFile, pFile->hMap));
+      return winLogError(SQLITE_IOERR_MMAP, pFile->lastErrno,
+                         "winUnmapfile2", pFile->zPath);
+    }
+    pFile->hMap = NULL;
+  }
+  OSTRACE(("UNMAP-FILE pid=%lu, pFile=%p, rc=SQLITE_OK\n",
+           osGetCurrentProcessId(), pFile));
+  return SQLITE_OK;
+}
+
+/*
+** Memory map or remap the file opened by file-descriptor pFd (if the file
+** is already mapped, the existing mapping is replaced by the new). Or, if
+** there already exists a mapping for this file, and there are still
+** outstanding xFetch() references to it, this function is a no-op.
+**
+** If parameter nByte is non-negative, then it is the requested size of
+** the mapping to create. Otherwise, if nByte is less than zero, then the
+** requested size is the size of the file on disk. The actual size of the
+** created mapping is either the requested size or the value configured
+** using SQLITE_FCNTL_MMAP_SIZE, whichever is smaller.
+**
+** SQLITE_OK is returned if no error occurs (even if the mapping is not
+** recreated as a result of outstanding references) or an SQLite error
+** code otherwise.
+*/
+static int winMapfile(winFile *pFd, sqlite3_int64 nByte){
+  sqlite3_int64 nMap = nByte;
+  int rc;
+
+  assert( nMap>=0 || pFd->nFetchOut==0 );
+  OSTRACE(("MAP-FILE pid=%lu, pFile=%p, size=%lld\n",
+           osGetCurrentProcessId(), pFd, nByte));
+
+  if( pFd->nFetchOut>0 ) return SQLITE_OK;
+
+  if( nMap<0 ){
+    rc = winFileSize((sqlite3_file*)pFd, &nMap);
+    if( rc ){
+      OSTRACE(("MAP-FILE pid=%lu, pFile=%p, rc=SQLITE_IOERR_FSTAT\n",
+               osGetCurrentProcessId(), pFd));
+      return SQLITE_IOERR_FSTAT;
+    }
+  }
+  if( nMap>pFd->mmapSizeMax ){
+    nMap = pFd->mmapSizeMax;
+  }
+  nMap &= ~(sqlite3_int64)(winSysInfo.dwPageSize - 1);
+
+  if( nMap==0 && pFd->mmapSize>0 ){
+    winUnmapfile(pFd);
+  }
+  if( nMap!=pFd->mmapSize ){
+    void *pNew = 0;
+    DWORD protect = PAGE_READONLY;
+    DWORD flags = FILE_MAP_READ;
+
+    winUnmapfile(pFd);
+#ifdef SQLITE_MMAP_READWRITE
+    if( (pFd->ctrlFlags & WINFILE_RDONLY)==0 ){
+      protect = PAGE_READWRITE;
+      flags |= FILE_MAP_WRITE;
+    }
+#endif
+#if SQLITE_OS_WINRT
+    pFd->hMap = osCreateFileMappingFromApp(pFd->h, NULL, protect, nMap, NULL);
+#elif defined(SQLITE_WIN32_HAS_WIDE)
+    pFd->hMap = osCreateFileMappingW(pFd->h, NULL, protect,
+                                (DWORD)((nMap>>32) & 0xffffffff),
+                                (DWORD)(nMap & 0xffffffff), NULL);
+#elif defined(SQLITE_WIN32_HAS_ANSI) && SQLITE_WIN32_CREATEFILEMAPPINGA
+    pFd->hMap = osCreateFileMappingA(pFd->h, NULL, protect,
+                                (DWORD)((nMap>>32) & 0xffffffff),
+                                (DWORD)(nMap & 0xffffffff), NULL);
+#endif
+    if( pFd->hMap==NULL ){
+      pFd->lastErrno = osGetLastError();
+      rc = winLogError(SQLITE_IOERR_MMAP, pFd->lastErrno,
+                       "winMapfile1", pFd->zPath);
+      /* Log the error, but continue normal operation using xRead/xWrite */
+      OSTRACE(("MAP-FILE-CREATE pid=%lu, pFile=%p, rc=%s\n",
+               osGetCurrentProcessId(), pFd, sqlite3ErrName(rc)));
+      return SQLITE_OK;
+    }
+    assert( (nMap % winSysInfo.dwPageSize)==0 );
+    assert( sizeof(SIZE_T)==sizeof(sqlite3_int64) || nMap<=0xffffffff );
+#if SQLITE_OS_WINRT
+    pNew = osMapViewOfFileFromApp(pFd->hMap, flags, 0, (SIZE_T)nMap);
+#else
+    pNew = osMapViewOfFile(pFd->hMap, flags, 0, 0, (SIZE_T)nMap);
+#endif
+    if( pNew==NULL ){
+      osCloseHandle(pFd->hMap);
+      pFd->hMap = NULL;
+      pFd->lastErrno = osGetLastError();
+      rc = winLogError(SQLITE_IOERR_MMAP, pFd->lastErrno,
+                       "winMapfile2", pFd->zPath);
+      /* Log the error, but continue normal operation using xRead/xWrite */
+      OSTRACE(("MAP-FILE-MAP pid=%lu, pFile=%p, rc=%s\n",
+               osGetCurrentProcessId(), pFd, sqlite3ErrName(rc)));
+      return SQLITE_OK;
+    }
+    pFd->pMapRegion = pNew;
+    pFd->mmapSize = nMap;
+    pFd->mmapSizeActual = nMap;
+  }
+
+  OSTRACE(("MAP-FILE pid=%lu, pFile=%p, rc=SQLITE_OK\n",
+           osGetCurrentProcessId(), pFd));
+  return SQLITE_OK;
+}
+#endif /* SQLITE_MAX_MMAP_SIZE>0 */
+
+/*
+** If possible, return a pointer to a mapping of file fd starting at offset
+** iOff. The mapping must be valid for at least nAmt bytes.
+**
+** If such a pointer can be obtained, store it in *pp and return SQLITE_OK.
+** Or, if one cannot but no error occurs, set *pp to 0 and return SQLITE_OK.
+** Finally, if an error does occur, return an SQLite error code. The final
+** value of *pp is undefined in this case.
+**
+** If this function does return a pointer, the caller must eventually
+** release the reference by calling winUnfetch().
+*/
+static int winFetch(sqlite3_file *fd, i64 iOff, int nAmt, void **pp){
+#if SQLITE_MAX_MMAP_SIZE>0
+  winFile *pFd = (winFile*)fd;   /* The underlying database file */
+#endif
+  *pp = 0;
+
+  OSTRACE(("FETCH pid=%lu, pFile=%p, offset=%lld, amount=%d, pp=%p\n",
+           osGetCurrentProcessId(), fd, iOff, nAmt, pp));
+
+#if SQLITE_MAX_MMAP_SIZE>0
+  if( pFd->mmapSizeMax>0 ){
+    if( pFd->pMapRegion==0 ){
+      int rc = winMapfile(pFd, -1);
+      if( rc!=SQLITE_OK ){
+        OSTRACE(("FETCH pid=%lu, pFile=%p, rc=%s\n",
+                 osGetCurrentProcessId(), pFd, sqlite3ErrName(rc)));
+        return rc;
+      }
+    }
+    if( pFd->mmapSize >= iOff+nAmt ){
+      *pp = &((u8 *)pFd->pMapRegion)[iOff];
+      pFd->nFetchOut++;
+    }
+  }
+#endif
+
+  OSTRACE(("FETCH pid=%lu, pFile=%p, pp=%p, *pp=%p, rc=SQLITE_OK\n",
+           osGetCurrentProcessId(), fd, pp, *pp));
+  return SQLITE_OK;
+}
+
+/*
+** If the third argument is non-NULL, then this function releases a
+** reference obtained by an earlier call to winFetch(). The second
+** argument passed to this function must be the same as the corresponding
+** argument that was passed to the winFetch() invocation.
+**
+** Or, if the third argument is NULL, then this function is being called
+** to inform the VFS layer that, according to POSIX, any existing mapping
+** may now be invalid and should be unmapped.
+*/
+static int winUnfetch(sqlite3_file *fd, i64 iOff, void *p){
+#if SQLITE_MAX_MMAP_SIZE>0
+  winFile *pFd = (winFile*)fd;   /* The underlying database file */
+
+  /* If p==0 (unmap the entire file) then there must be no outstanding
+  ** xFetch references. Or, if p!=0 (meaning it is an xFetch reference),
+  ** then there must be at least one outstanding.  */
+  assert( (p==0)==(pFd->nFetchOut==0) );
+
+  /* If p!=0, it must match the iOff value. */
+  assert( p==0 || p==&((u8 *)pFd->pMapRegion)[iOff] );
+
+  OSTRACE(("UNFETCH pid=%lu, pFile=%p, offset=%lld, p=%p\n",
+           osGetCurrentProcessId(), pFd, iOff, p));
+
+  if( p ){
+    pFd->nFetchOut--;
+  }else{
+    /* FIXME:  If Windows truly always prevents truncating or deleting a
+    ** file while a mapping is held, then the following winUnmapfile() call
+    ** is unnecessary can be omitted - potentially improving
+    ** performance.  */
+    winUnmapfile(pFd);
+  }
+
+  assert( pFd->nFetchOut>=0 );
+#endif
+
+  OSTRACE(("UNFETCH pid=%lu, pFile=%p, rc=SQLITE_OK\n",
+           osGetCurrentProcessId(), fd));
+  return SQLITE_OK;
+}
+
+/*
+** Here ends the implementation of all sqlite3_file methods.
+**
+********************** End sqlite3_file Methods *******************************
+******************************************************************************/
+
+/*
+** This vector defines all the methods that can operate on an
+** sqlite3_file for win32.
+*/
+static const sqlite3_io_methods winIoMethod = {
+  3,                              /* iVersion */
+  winClose,                       /* xClose */
+  winRead,                        /* xRead */
+  winWrite,                       /* xWrite */
+  winTruncate,                    /* xTruncate */
+  winSync,                        /* xSync */
+  winFileSize,                    /* xFileSize */
+  winLock,                        /* xLock */
+  winUnlock,                      /* xUnlock */
+  winCheckReservedLock,           /* xCheckReservedLock */
+  winFileControl,                 /* xFileControl */
+  winSectorSize,                  /* xSectorSize */
+  winDeviceCharacteristics,       /* xDeviceCharacteristics */
+  winShmMap,                      /* xShmMap */
+  winShmLock,                     /* xShmLock */
+  winShmBarrier,                  /* xShmBarrier */
+  winShmUnmap,                    /* xShmUnmap */
+  winFetch,                       /* xFetch */
+  winUnfetch                      /* xUnfetch */
+};
+
+/*
+** This vector defines all the methods that can operate on an
+** sqlite3_file for win32 without performing any locking.
+*/
+static const sqlite3_io_methods winIoNolockMethod = {
+  3,                              /* iVersion */
+  winClose,                       /* xClose */
+  winRead,                        /* xRead */
+  winWrite,                       /* xWrite */
+  winTruncate,                    /* xTruncate */
+  winSync,                        /* xSync */
+  winFileSize,                    /* xFileSize */
+  winNolockLock,                  /* xLock */
+  winNolockUnlock,                /* xUnlock */
+  winNolockCheckReservedLock,     /* xCheckReservedLock */
+  winFileControl,                 /* xFileControl */
+  winSectorSize,                  /* xSectorSize */
+  winDeviceCharacteristics,       /* xDeviceCharacteristics */
+  winShmMap,                      /* xShmMap */
+  winShmLock,                     /* xShmLock */
+  winShmBarrier,                  /* xShmBarrier */
+  winShmUnmap,                    /* xShmUnmap */
+  winFetch,                       /* xFetch */
+  winUnfetch                      /* xUnfetch */
+};
+
+static winVfsAppData winAppData = {
+  &winIoMethod,       /* pMethod */
+  0,                  /* pAppData */
+  0                   /* bNoLock */
+};
+
+static winVfsAppData winNolockAppData = {
+  &winIoNolockMethod, /* pMethod */
+  0,                  /* pAppData */
+  1                   /* bNoLock */
+};
+
+/****************************************************************************
+**************************** sqlite3_vfs methods ****************************
+**
+** This division contains the implementation of methods on the
+** sqlite3_vfs object.
+*/
+
+#if defined(__CYGWIN__)
+/*
+** Convert a filename from whatever the underlying operating system
+** supports for filenames into UTF-8.  Space to hold the result is
+** obtained from malloc and must be freed by the calling function.
+*/
+static char *winConvertToUtf8Filename(const void *zFilename){
+  char *zConverted = 0;
+  if( osIsNT() ){
+    zConverted = winUnicodeToUtf8(zFilename);
+  }
+#ifdef SQLITE_WIN32_HAS_ANSI
+  else{
+    zConverted = winMbcsToUtf8(zFilename, osAreFileApisANSI());
+  }
+#endif
+  /* caller will handle out of memory */
+  return zConverted;
+}
+#endif
+
+/*
+** Convert a UTF-8 filename into whatever form the underlying
+** operating system wants filenames in.  Space to hold the result
+** is obtained from malloc and must be freed by the calling
+** function.
+*/
+static void *winConvertFromUtf8Filename(const char *zFilename){
+  void *zConverted = 0;
+  if( osIsNT() ){
+    zConverted = winUtf8ToUnicode(zFilename);
+  }
+#ifdef SQLITE_WIN32_HAS_ANSI
+  else{
+    zConverted = winUtf8ToMbcs(zFilename, osAreFileApisANSI());
+  }
+#endif
+  /* caller will handle out of memory */
+  return zConverted;
+}
+
+/*
+** This function returns non-zero if the specified UTF-8 string buffer
+** ends with a directory separator character or one was successfully
+** added to it.
+*/
+static int winMakeEndInDirSep(int nBuf, char *zBuf){
+  if( zBuf ){
+    int nLen = sqlite3Strlen30(zBuf);
+    if( nLen>0 ){
+      if( winIsDirSep(zBuf[nLen-1]) ){
+        return 1;
+      }else if( nLen+1<nBuf ){
+        zBuf[nLen] = winGetDirSep();
+        zBuf[nLen+1] = '\0';
+        return 1;
+      }
+    }
+  }
+  return 0;
+}
+
+/*
+** Create a temporary file name and store the resulting pointer into pzBuf.
+** The pointer returned in pzBuf must be freed via sqlite3_free().
+*/
+static int winGetTempname(sqlite3_vfs *pVfs, char **pzBuf){
+  static char zChars[] =
+    "abcdefghijklmnopqrstuvwxyz"
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+    "0123456789";
+  size_t i, j;
+  int nPre = sqlite3Strlen30(SQLITE_TEMP_FILE_PREFIX);
+  int nMax, nBuf, nDir, nLen;
+  char *zBuf;
+
+  /* It's odd to simulate an io-error here, but really this is just
+  ** using the io-error infrastructure to test that SQLite handles this
+  ** function failing.
+  */
+  SimulateIOError( return SQLITE_IOERR );
+
+  /* Allocate a temporary buffer to store the fully qualified file
+  ** name for the temporary file.  If this fails, we cannot continue.
+  */
+  nMax = pVfs->mxPathname; nBuf = nMax + 2;
+  zBuf = sqlite3MallocZero( nBuf );
+  if( !zBuf ){
+    OSTRACE(("TEMP-FILENAME rc=SQLITE_IOERR_NOMEM\n"));
+    return SQLITE_IOERR_NOMEM_BKPT;
+  }
+
+  /* Figure out the effective temporary directory.  First, check if one
+  ** has been explicitly set by the application; otherwise, use the one
+  ** configured by the operating system.
+  */
+  nDir = nMax - (nPre + 15);
+  assert( nDir>0 );
+  if( sqlite3_temp_directory ){
+    int nDirLen = sqlite3Strlen30(sqlite3_temp_directory);
+    if( nDirLen>0 ){
+      if( !winIsDirSep(sqlite3_temp_directory[nDirLen-1]) ){
+        nDirLen++;
+      }
+      if( nDirLen>nDir ){
+        sqlite3_free(zBuf);
+        OSTRACE(("TEMP-FILENAME rc=SQLITE_ERROR\n"));
+        return winLogError(SQLITE_ERROR, 0, "winGetTempname1", 0);
+      }
+      sqlite3_snprintf(nMax, zBuf, "%s", sqlite3_temp_directory);
+    }
+  }
+#if defined(__CYGWIN__)
+  else{
+    static const char *azDirs[] = {
+       0, /* getenv("SQLITE_TMPDIR") */
+       0, /* getenv("TMPDIR") */
+       0, /* getenv("TMP") */
+       0, /* getenv("TEMP") */
+       0, /* getenv("USERPROFILE") */
+       "/var/tmp",
+       "/usr/tmp",
+       "/tmp",
+       ".",
+       0        /* List terminator */
+    };
+    unsigned int i;
+    const char *zDir = 0;
+
+    if( !azDirs[0] ) azDirs[0] = getenv("SQLITE_TMPDIR");
+    if( !azDirs[1] ) azDirs[1] = getenv("TMPDIR");
+    if( !azDirs[2] ) azDirs[2] = getenv("TMP");
+    if( !azDirs[3] ) azDirs[3] = getenv("TEMP");
+    if( !azDirs[4] ) azDirs[4] = getenv("USERPROFILE");
+    for(i=0; i<sizeof(azDirs)/sizeof(azDirs[0]); zDir=azDirs[i++]){
+      void *zConverted;
+      if( zDir==0 ) continue;
+      /* If the path starts with a drive letter followed by the colon
+      ** character, assume it is already a native Win32 path; otherwise,
+      ** it must be converted to a native Win32 path via the Cygwin API
+      ** prior to using it.
+      */
+      if( winIsDriveLetterAndColon(zDir) ){
+        zConverted = winConvertFromUtf8Filename(zDir);
+        if( !zConverted ){
+          sqlite3_free(zBuf);
+          OSTRACE(("TEMP-FILENAME rc=SQLITE_IOERR_NOMEM\n"));
+          return SQLITE_IOERR_NOMEM_BKPT;
+        }
+        if( winIsDir(zConverted) ){
+          sqlite3_snprintf(nMax, zBuf, "%s", zDir);
+          sqlite3_free(zConverted);
+          break;
+        }
+        sqlite3_free(zConverted);
+      }else{
+        zConverted = sqlite3MallocZero( nMax+1 );
+        if( !zConverted ){
+          sqlite3_free(zBuf);
+          OSTRACE(("TEMP-FILENAME rc=SQLITE_IOERR_NOMEM\n"));
+          return SQLITE_IOERR_NOMEM_BKPT;
+        }
+        if( cygwin_conv_path(
+                osIsNT() ? CCP_POSIX_TO_WIN_W : CCP_POSIX_TO_WIN_A, zDir,
+                zConverted, nMax+1)<0 ){
+          sqlite3_free(zConverted);
+          sqlite3_free(zBuf);
+          OSTRACE(("TEMP-FILENAME rc=SQLITE_IOERR_CONVPATH\n"));
+          return winLogError(SQLITE_IOERR_CONVPATH, (DWORD)errno,
+                             "winGetTempname2", zDir);
+        }
+        if( winIsDir(zConverted) ){
+          /* At this point, we know the candidate directory exists and should
+          ** be used.  However, we may need to convert the string containing
+          ** its name into UTF-8 (i.e. if it is UTF-16 right now).
+          */
+          char *zUtf8 = winConvertToUtf8Filename(zConverted);
+          if( !zUtf8 ){
+            sqlite3_free(zConverted);
+            sqlite3_free(zBuf);
+            OSTRACE(("TEMP-FILENAME rc=SQLITE_IOERR_NOMEM\n"));
+            return SQLITE_IOERR_NOMEM_BKPT;
+          }
+          sqlite3_snprintf(nMax, zBuf, "%s", zUtf8);
+          sqlite3_free(zUtf8);
+          sqlite3_free(zConverted);
+          break;
+        }
+        sqlite3_free(zConverted);
+      }
+    }
+  }
+#elif !SQLITE_OS_WINRT && !defined(__CYGWIN__)
+  else if( osIsNT() ){
+    char *zMulti;
+    LPWSTR zWidePath = sqlite3MallocZero( nMax*sizeof(WCHAR) );
+    if( !zWidePath ){
+      sqlite3_free(zBuf);
+      OSTRACE(("TEMP-FILENAME rc=SQLITE_IOERR_NOMEM\n"));
+      return SQLITE_IOERR_NOMEM_BKPT;
+    }
+    if( osGetTempPathW(nMax, zWidePath)==0 ){
+      sqlite3_free(zWidePath);
+      sqlite3_free(zBuf);
+      OSTRACE(("TEMP-FILENAME rc=SQLITE_IOERR_GETTEMPPATH\n"));
+      return winLogError(SQLITE_IOERR_GETTEMPPATH, osGetLastError(),
+                         "winGetTempname2", 0);
+    }
+    zMulti = winUnicodeToUtf8(zWidePath);
+    if( zMulti ){
+      sqlite3_snprintf(nMax, zBuf, "%s", zMulti);
+      sqlite3_free(zMulti);
+      sqlite3_free(zWidePath);
+    }else{
+      sqlite3_free(zWidePath);
+      sqlite3_free(zBuf);
+      OSTRACE(("TEMP-FILENAME rc=SQLITE_IOERR_NOMEM\n"));
+      return SQLITE_IOERR_NOMEM_BKPT;
+    }
+  }
+#ifdef SQLITE_WIN32_HAS_ANSI
+  else{
+    char *zUtf8;
+    char *zMbcsPath = sqlite3MallocZero( nMax );
+    if( !zMbcsPath ){
+      sqlite3_free(zBuf);
+      OSTRACE(("TEMP-FILENAME rc=SQLITE_IOERR_NOMEM\n"));
+      return SQLITE_IOERR_NOMEM_BKPT;
+    }
+    if( osGetTempPathA(nMax, zMbcsPath)==0 ){
+      sqlite3_free(zBuf);
+      OSTRACE(("TEMP-FILENAME rc=SQLITE_IOERR_GETTEMPPATH\n"));
+      return winLogError(SQLITE_IOERR_GETTEMPPATH, osGetLastError(),
+                         "winGetTempname3", 0);
+    }
+    zUtf8 = winMbcsToUtf8(zMbcsPath, osAreFileApisANSI());
+    if( zUtf8 ){
+      sqlite3_snprintf(nMax, zBuf, "%s", zUtf8);
+      sqlite3_free(zUtf8);
+    }else{
+      sqlite3_free(zBuf);
+      OSTRACE(("TEMP-FILENAME rc=SQLITE_IOERR_NOMEM\n"));
+      return SQLITE_IOERR_NOMEM_BKPT;
+    }
+  }
+#endif /* SQLITE_WIN32_HAS_ANSI */
+#endif /* !SQLITE_OS_WINRT */
+
+  /*
+  ** Check to make sure the temporary directory ends with an appropriate
+  ** separator.  If it does not and there is not enough space left to add
+  ** one, fail.
+  */
+  if( !winMakeEndInDirSep(nDir+1, zBuf) ){
+    sqlite3_free(zBuf);
+    OSTRACE(("TEMP-FILENAME rc=SQLITE_ERROR\n"));
+    return winLogError(SQLITE_ERROR, 0, "winGetTempname4", 0);
+  }
+
+  /*
+  ** Check that the output buffer is large enough for the temporary file
+  ** name in the following format:
+  **
+  **   "<temporary_directory>/etilqs_XXXXXXXXXXXXXXX\0\0"
+  **
+  ** If not, return SQLITE_ERROR.  The number 17 is used here in order to
+  ** account for the space used by the 15 character random suffix and the
+  ** two trailing NUL characters.  The final directory separator character
+  ** has already added if it was not already present.
+  */
+  nLen = sqlite3Strlen30(zBuf);
+  if( (nLen + nPre + 17) > nBuf ){
+    sqlite3_free(zBuf);
+    OSTRACE(("TEMP-FILENAME rc=SQLITE_ERROR\n"));
+    return winLogError(SQLITE_ERROR, 0, "winGetTempname5", 0);
+  }
+
+  sqlite3_snprintf(nBuf-16-nLen, zBuf+nLen, SQLITE_TEMP_FILE_PREFIX);
+
+  j = sqlite3Strlen30(zBuf);
+  sqlite3_randomness(15, &zBuf[j]);
+  for(i=0; i<15; i++, j++){
+    zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
+  }
+  zBuf[j] = 0;
+  zBuf[j+1] = 0;
+  *pzBuf = zBuf;
+
+  OSTRACE(("TEMP-FILENAME name=%s, rc=SQLITE_OK\n", zBuf));
+  return SQLITE_OK;
+}
+
+/*
+** Return TRUE if the named file is really a directory.  Return false if
+** it is something other than a directory, or if there is any kind of memory
+** allocation failure.
+*/
+static int winIsDir(const void *zConverted){
+  DWORD attr;
+  int rc = 0;
+  DWORD lastErrno;
+
+  if( osIsNT() ){
+    int cnt = 0;
+    WIN32_FILE_ATTRIBUTE_DATA sAttrData;
+    memset(&sAttrData, 0, sizeof(sAttrData));
+    while( !(rc = osGetFileAttributesExW((LPCWSTR)zConverted,
+                             GetFileExInfoStandard,
+                             &sAttrData)) && winRetryIoerr(&cnt, &lastErrno) ){}
+    if( !rc ){
+      return 0; /* Invalid name? */
+    }
+    attr = sAttrData.dwFileAttributes;
+#if SQLITE_OS_WINCE==0
+  }else{
+    attr = osGetFileAttributesA((char*)zConverted);
+#endif
+  }
+  return (attr!=INVALID_FILE_ATTRIBUTES) && (attr&FILE_ATTRIBUTE_DIRECTORY);
+}
+
+/*
+** Open a file.
+*/
+static int winOpen(
+  sqlite3_vfs *pVfs,        /* Used to get maximum path length and AppData */
+  const char *zName,        /* Name of the file (UTF-8) */
+  sqlite3_file *id,         /* Write the SQLite file handle here */
+  int flags,                /* Open mode flags */
+  int *pOutFlags            /* Status return flags */
+){
+  HANDLE h;
+  DWORD lastErrno = 0;
+  DWORD dwDesiredAccess;
+  DWORD dwShareMode;
+  DWORD dwCreationDisposition;
+  DWORD dwFlagsAndAttributes = 0;
+#if SQLITE_OS_WINCE
+  int isTemp = 0;
+#endif
+  winVfsAppData *pAppData;
+  winFile *pFile = (winFile*)id;
+  void *zConverted;              /* Filename in OS encoding */
+  const char *zUtf8Name = zName; /* Filename in UTF-8 encoding */
+  int cnt = 0;
+
+  /* If argument zPath is a NULL pointer, this function is required to open
+  ** a temporary file. Use this buffer to store the file name in.
+  */
+  char *zTmpname = 0; /* For temporary filename, if necessary. */
+
+  int rc = SQLITE_OK;            /* Function Return Code */
+#if !defined(NDEBUG) || SQLITE_OS_WINCE
+  int eType = flags&0xFFFFFF00;  /* Type of file to open */
+#endif
+
+  int isExclusive  = (flags & SQLITE_OPEN_EXCLUSIVE);
+  int isDelete     = (flags & SQLITE_OPEN_DELETEONCLOSE);
+  int isCreate     = (flags & SQLITE_OPEN_CREATE);
+  int isReadonly   = (flags & SQLITE_OPEN_READONLY);
+  int isReadWrite  = (flags & SQLITE_OPEN_READWRITE);
+
+#ifndef NDEBUG
+  int isOpenJournal = (isCreate && (
+        eType==SQLITE_OPEN_MASTER_JOURNAL
+     || eType==SQLITE_OPEN_MAIN_JOURNAL
+     || eType==SQLITE_OPEN_WAL
+  ));
+#endif
+
+  OSTRACE(("OPEN name=%s, pFile=%p, flags=%x, pOutFlags=%p\n",
+           zUtf8Name, id, flags, pOutFlags));
+
+  /* Check the following statements are true:
+  **
+  **   (a) Exactly one of the READWRITE and READONLY flags must be set, and
+  **   (b) if CREATE is set, then READWRITE must also be set, and
+  **   (c) if EXCLUSIVE is set, then CREATE must also be set.
+  **   (d) if DELETEONCLOSE is set, then CREATE must also be set.
+  */
+  assert((isReadonly==0 || isReadWrite==0) && (isReadWrite || isReadonly));
+  assert(isCreate==0 || isReadWrite);
+  assert(isExclusive==0 || isCreate);
+  assert(isDelete==0 || isCreate);
+
+  /* The main DB, main journal, WAL file and master journal are never
+  ** automatically deleted. Nor are they ever temporary files.  */
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_DB );
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_JOURNAL );
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MASTER_JOURNAL );
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_WAL );
+
+  /* Assert that the upper layer has set one of the "file-type" flags. */
+  assert( eType==SQLITE_OPEN_MAIN_DB      || eType==SQLITE_OPEN_TEMP_DB
+       || eType==SQLITE_OPEN_MAIN_JOURNAL || eType==SQLITE_OPEN_TEMP_JOURNAL
+       || eType==SQLITE_OPEN_SUBJOURNAL   || eType==SQLITE_OPEN_MASTER_JOURNAL
+       || eType==SQLITE_OPEN_TRANSIENT_DB || eType==SQLITE_OPEN_WAL
+  );
+
+  assert( pFile!=0 );
+  memset(pFile, 0, sizeof(winFile));
+  pFile->h = INVALID_HANDLE_VALUE;
+
+#if SQLITE_OS_WINRT
+  if( !zUtf8Name && !sqlite3_temp_directory ){
+    sqlite3_log(SQLITE_ERROR,
+        "sqlite3_temp_directory variable should be set for WinRT");
+  }
+#endif
+
+  /* If the second argument to this function is NULL, generate a
+  ** temporary file name to use
+  */
+  if( !zUtf8Name ){
+    assert( isDelete && !isOpenJournal );
+    rc = winGetTempname(pVfs, &zTmpname);
+    if( rc!=SQLITE_OK ){
+      OSTRACE(("OPEN name=%s, rc=%s", zUtf8Name, sqlite3ErrName(rc)));
+      return rc;
+    }
+    zUtf8Name = zTmpname;
+  }
+
+  /* Database filenames are double-zero terminated if they are not
+  ** URIs with parameters.  Hence, they can always be passed into
+  ** sqlite3_uri_parameter().
+  */
+  assert( (eType!=SQLITE_OPEN_MAIN_DB) || (flags & SQLITE_OPEN_URI) ||
+       zUtf8Name[sqlite3Strlen30(zUtf8Name)+1]==0 );
+
+  /* Convert the filename to the system encoding. */
+  zConverted = winConvertFromUtf8Filename(zUtf8Name);
+  if( zConverted==0 ){
+    sqlite3_free(zTmpname);
+    OSTRACE(("OPEN name=%s, rc=SQLITE_IOERR_NOMEM", zUtf8Name));
+    return SQLITE_IOERR_NOMEM_BKPT;
+  }
+
+  if( winIsDir(zConverted) ){
+    sqlite3_free(zConverted);
+    sqlite3_free(zTmpname);
+    OSTRACE(("OPEN name=%s, rc=SQLITE_CANTOPEN_ISDIR", zUtf8Name));
+    return SQLITE_CANTOPEN_ISDIR;
+  }
+
+  if( isReadWrite ){
+    dwDesiredAccess = GENERIC_READ | GENERIC_WRITE;
+  }else{
+    dwDesiredAccess = GENERIC_READ;
+  }
+
+  /* SQLITE_OPEN_EXCLUSIVE is used to make sure that a new file is
+  ** created. SQLite doesn't use it to indicate "exclusive access"
+  ** as it is usually understood.
+  */
+  if( isExclusive ){
+    /* Creates a new file, only if it does not already exist. */
+    /* If the file exists, it fails. */
+    dwCreationDisposition = CREATE_NEW;
+  }else if( isCreate ){
+    /* Open existing file, or create if it doesn't exist */
+    dwCreationDisposition = OPEN_ALWAYS;
+  }else{
+    /* Opens a file, only if it exists. */
+    dwCreationDisposition = OPEN_EXISTING;
+  }
+
+  dwShareMode = FILE_SHARE_READ | FILE_SHARE_WRITE;
+
+  // TDLib: fix for TDLib. We will delete an opened database if it is corrupted
+  dwShareMode |= FILE_SHARE_DELETE;
+
+  if( isDelete ){
+#if SQLITE_OS_WINCE
+    dwFlagsAndAttributes = FILE_ATTRIBUTE_HIDDEN;
+    isTemp = 1;
+#else
+    dwFlagsAndAttributes = FILE_ATTRIBUTE_TEMPORARY
+                               | FILE_ATTRIBUTE_HIDDEN
+                               | FILE_FLAG_DELETE_ON_CLOSE;
+#endif
+  }else{
+    dwFlagsAndAttributes = FILE_ATTRIBUTE_NORMAL;
+  }
+  /* Reports from the internet are that performance is always
+  ** better if FILE_FLAG_RANDOM_ACCESS is used.  Ticket #2699. */
+#if SQLITE_OS_WINCE
+  dwFlagsAndAttributes |= FILE_FLAG_RANDOM_ACCESS;
+#endif
+
+  if( osIsNT() ){
+#if SQLITE_OS_WINRT
+    CREATEFILE2_EXTENDED_PARAMETERS extendedParameters;
+    extendedParameters.dwSize = sizeof(CREATEFILE2_EXTENDED_PARAMETERS);
+    extendedParameters.dwFileAttributes =
+            dwFlagsAndAttributes & FILE_ATTRIBUTE_MASK;
+    extendedParameters.dwFileFlags = dwFlagsAndAttributes & FILE_FLAG_MASK;
+    extendedParameters.dwSecurityQosFlags = SECURITY_ANONYMOUS;
+    extendedParameters.lpSecurityAttributes = NULL;
+    extendedParameters.hTemplateFile = NULL;
+    while( (h = osCreateFile2((LPCWSTR)zConverted,
+                              dwDesiredAccess,
+                              dwShareMode,
+                              dwCreationDisposition,
+                              &extendedParameters))==INVALID_HANDLE_VALUE &&
+                              winRetryIoerr(&cnt, &lastErrno) ){
+               /* Noop */
+    }
+#else
+    while( (h = osCreateFileW((LPCWSTR)zConverted,
+                              dwDesiredAccess,
+                              dwShareMode, NULL,
+                              dwCreationDisposition,
+                              dwFlagsAndAttributes,
+                              NULL))==INVALID_HANDLE_VALUE &&
+                              winRetryIoerr(&cnt, &lastErrno) ){
+               /* Noop */
+    }
+#endif
+  }
+#ifdef SQLITE_WIN32_HAS_ANSI
+  else{
+    while( (h = osCreateFileA((LPCSTR)zConverted,
+                              dwDesiredAccess,
+                              dwShareMode, NULL,
+                              dwCreationDisposition,
+                              dwFlagsAndAttributes,
+                              NULL))==INVALID_HANDLE_VALUE &&
+                              winRetryIoerr(&cnt, &lastErrno) ){
+               /* Noop */
+    }
+  }
+#endif
+  winLogIoerr(cnt, __LINE__);
+
+  OSTRACE(("OPEN file=%p, name=%s, access=%lx, rc=%s\n", h, zUtf8Name,
+           dwDesiredAccess, (h==INVALID_HANDLE_VALUE) ? "failed" : "ok"));
+
+  if( h==INVALID_HANDLE_VALUE ){
+    pFile->lastErrno = lastErrno;
+    winLogError(SQLITE_CANTOPEN, pFile->lastErrno, "winOpen", zUtf8Name);
+    sqlite3_free(zConverted);
+    sqlite3_free(zTmpname);
+    if( isReadWrite && !isExclusive ){
+      return winOpen(pVfs, zName, id,
+         ((flags|SQLITE_OPEN_READONLY) &
+                     ~(SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE)),
+         pOutFlags);
+    }else{
+      return SQLITE_CANTOPEN_BKPT;
+    }
+  }
+
+  if( pOutFlags ){
+    if( isReadWrite ){
+      *pOutFlags = SQLITE_OPEN_READWRITE;
+    }else{
+      *pOutFlags = SQLITE_OPEN_READONLY;
+    }
+  }
+
+  OSTRACE(("OPEN file=%p, name=%s, access=%lx, pOutFlags=%p, *pOutFlags=%d, "
+           "rc=%s\n", h, zUtf8Name, dwDesiredAccess, pOutFlags, pOutFlags ?
+           *pOutFlags : 0, (h==INVALID_HANDLE_VALUE) ? "failed" : "ok"));
+
+  pAppData = (winVfsAppData*)pVfs->pAppData;
+
+#if SQLITE_OS_WINCE
+  {
+    if( isReadWrite && eType==SQLITE_OPEN_MAIN_DB
+         && ((pAppData==NULL) || !pAppData->bNoLock)
+         && (rc = winceCreateLock(zName, pFile))!=SQLITE_OK
+    ){
+      osCloseHandle(h);
+      sqlite3_free(zConverted);
+      sqlite3_free(zTmpname);
+      OSTRACE(("OPEN-CE-LOCK name=%s, rc=%s\n", zName, sqlite3ErrName(rc)));
+      return rc;
+    }
+  }
+  if( isTemp ){
+    pFile->zDeleteOnClose = zConverted;
+  }else
+#endif
+  {
+    sqlite3_free(zConverted);
+  }
+
+  sqlite3_free(zTmpname);
+  pFile->pMethod = pAppData ? pAppData->pMethod : &winIoMethod;
+  pFile->pVfs = pVfs;
+  pFile->h = h;
+  if( isReadonly ){
+    pFile->ctrlFlags |= WINFILE_RDONLY;
+  }
+  if( sqlite3_uri_boolean(zName, "psow", SQLITE_POWERSAFE_OVERWRITE) ){
+    pFile->ctrlFlags |= WINFILE_PSOW;
+  }
+  pFile->lastErrno = NO_ERROR;
+  pFile->zPath = zName;
+#if SQLITE_MAX_MMAP_SIZE>0
+  pFile->hMap = NULL;
+  pFile->pMapRegion = 0;
+  pFile->mmapSize = 0;
+  pFile->mmapSizeActual = 0;
+  pFile->mmapSizeMax = sqlite3GlobalConfig.szMmap;
+#endif
+
+  OpenCounter(+1);
+  return rc;
+}
+
+/*
+** Delete the named file.
+**
+** Note that Windows does not allow a file to be deleted if some other
+** process has it open.  Sometimes a virus scanner or indexing program
+** will open a journal file shortly after it is created in order to do
+** whatever it does.  While this other process is holding the
+** file open, we will be unable to delete it.  To work around this
+** problem, we delay 100 milliseconds and try to delete again.  Up
+** to MX_DELETION_ATTEMPTs deletion attempts are run before giving
+** up and returning an error.
+*/
+static int winDelete(
+  sqlite3_vfs *pVfs,          /* Not used on win32 */
+  const char *zFilename,      /* Name of file to delete */
+  int syncDir                 /* Not used on win32 */
+){
+  int cnt = 0;
+  int rc;
+  DWORD attr;
+  DWORD lastErrno = 0;
+  void *zConverted;
+  UNUSED_PARAMETER(pVfs);
+  UNUSED_PARAMETER(syncDir);
+
+  SimulateIOError(return SQLITE_IOERR_DELETE);
+  OSTRACE(("DELETE name=%s, syncDir=%d\n", zFilename, syncDir));
+
+  zConverted = winConvertFromUtf8Filename(zFilename);
+  if( zConverted==0 ){
+    OSTRACE(("DELETE name=%s, rc=SQLITE_IOERR_NOMEM\n", zFilename));
+    return SQLITE_IOERR_NOMEM_BKPT;
+  }
+  if( osIsNT() ){
+    do {
+#if SQLITE_OS_WINRT
+      WIN32_FILE_ATTRIBUTE_DATA sAttrData;
+      memset(&sAttrData, 0, sizeof(sAttrData));
+      if ( osGetFileAttributesExW(zConverted, GetFileExInfoStandard,
+                                  &sAttrData) ){
+        attr = sAttrData.dwFileAttributes;
+      }else{
+        lastErrno = osGetLastError();
+        if( lastErrno==ERROR_FILE_NOT_FOUND
+         || lastErrno==ERROR_PATH_NOT_FOUND ){
+          rc = SQLITE_IOERR_DELETE_NOENT; /* Already gone? */
+        }else{
+          rc = SQLITE_ERROR;
+        }
+        break;
+      }
+#else
+      attr = osGetFileAttributesW(zConverted);
+#endif
+      if ( attr==INVALID_FILE_ATTRIBUTES ){
+        lastErrno = osGetLastError();
+        if( lastErrno==ERROR_FILE_NOT_FOUND
+         || lastErrno==ERROR_PATH_NOT_FOUND ){
+          rc = SQLITE_IOERR_DELETE_NOENT; /* Already gone? */
+        }else{
+          rc = SQLITE_ERROR;
+        }
+        break;
+      }
+      if ( attr&FILE_ATTRIBUTE_DIRECTORY ){
+        rc = SQLITE_ERROR; /* Files only. */
+        break;
+      }
+      if ( osDeleteFileW(zConverted) ){
+        rc = SQLITE_OK; /* Deleted OK. */
+        break;
+      }
+      if ( !winRetryIoerr(&cnt, &lastErrno) ){
+        rc = SQLITE_ERROR; /* No more retries. */
+        break;
+      }
+    } while(1);
+  }
+#ifdef SQLITE_WIN32_HAS_ANSI
+  else{
+    do {
+      attr = osGetFileAttributesA(zConverted);
+      if ( attr==INVALID_FILE_ATTRIBUTES ){
+        lastErrno = osGetLastError();
+        if( lastErrno==ERROR_FILE_NOT_FOUND
+         || lastErrno==ERROR_PATH_NOT_FOUND ){
+          rc = SQLITE_IOERR_DELETE_NOENT; /* Already gone? */
+        }else{
+          rc = SQLITE_ERROR;
+        }
+        break;
+      }
+      if ( attr&FILE_ATTRIBUTE_DIRECTORY ){
+        rc = SQLITE_ERROR; /* Files only. */
+        break;
+      }
+      if ( osDeleteFileA(zConverted) ){
+        rc = SQLITE_OK; /* Deleted OK. */
+        break;
+      }
+      if ( !winRetryIoerr(&cnt, &lastErrno) ){
+        rc = SQLITE_ERROR; /* No more retries. */
+        break;
+      }
+    } while(1);
+  }
+#endif
+  if( rc && rc!=SQLITE_IOERR_DELETE_NOENT ){
+    rc = winLogError(SQLITE_IOERR_DELETE, lastErrno, "winDelete", zFilename);
+  }else{
+    winLogIoerr(cnt, __LINE__);
+  }
+  sqlite3_free(zConverted);
+  OSTRACE(("DELETE name=%s, rc=%s\n", zFilename, sqlite3ErrName(rc)));
+  return rc;
+}
+
+/*
+** Check the existence and status of a file.
+*/
+static int winAccess(
+  sqlite3_vfs *pVfs,         /* Not used on win32 */
+  const char *zFilename,     /* Name of file to check */
+  int flags,                 /* Type of test to make on this file */
+  int *pResOut               /* OUT: Result */
+){
+  DWORD attr;
+  int rc = 0;
+  DWORD lastErrno = 0;
+  void *zConverted;
+  UNUSED_PARAMETER(pVfs);
+
+  SimulateIOError( return SQLITE_IOERR_ACCESS; );
+  OSTRACE(("ACCESS name=%s, flags=%x, pResOut=%p\n",
+           zFilename, flags, pResOut));
+
+  zConverted = winConvertFromUtf8Filename(zFilename);
+  if( zConverted==0 ){
+    OSTRACE(("ACCESS name=%s, rc=SQLITE_IOERR_NOMEM\n", zFilename));
+    return SQLITE_IOERR_NOMEM_BKPT;
+  }
+  if( osIsNT() ){
+    int cnt = 0;
+    WIN32_FILE_ATTRIBUTE_DATA sAttrData;
+    memset(&sAttrData, 0, sizeof(sAttrData));
+    while( !(rc = osGetFileAttributesExW((LPCWSTR)zConverted,
+                             GetFileExInfoStandard,
+                             &sAttrData)) && winRetryIoerr(&cnt, &lastErrno) ){}
+    if( rc ){
+      /* For an SQLITE_ACCESS_EXISTS query, treat a zero-length file
+      ** as if it does not exist.
+      */
+      if(    flags==SQLITE_ACCESS_EXISTS
+          && sAttrData.nFileSizeHigh==0
+          && sAttrData.nFileSizeLow==0 ){
+        attr = INVALID_FILE_ATTRIBUTES;
+      }else{
+        attr = sAttrData.dwFileAttributes;
+      }
+    }else{
+      winLogIoerr(cnt, __LINE__);
+      if( lastErrno!=ERROR_FILE_NOT_FOUND && lastErrno!=ERROR_PATH_NOT_FOUND ){
+        sqlite3_free(zConverted);
+        return winLogError(SQLITE_IOERR_ACCESS, lastErrno, "winAccess",
+                           zFilename);
+      }else{
+        attr = INVALID_FILE_ATTRIBUTES;
+      }
+    }
+  }
+#ifdef SQLITE_WIN32_HAS_ANSI
+  else{
+    attr = osGetFileAttributesA((char*)zConverted);
+  }
+#endif
+  sqlite3_free(zConverted);
+  switch( flags ){
+    case SQLITE_ACCESS_READ:
+    case SQLITE_ACCESS_EXISTS:
+      rc = attr!=INVALID_FILE_ATTRIBUTES;
+      break;
+    case SQLITE_ACCESS_READWRITE:
+      rc = attr!=INVALID_FILE_ATTRIBUTES &&
+             (attr & FILE_ATTRIBUTE_READONLY)==0;
+      break;
+    default:
+      assert(!"Invalid flags argument");
+  }
+  *pResOut = rc;
+  OSTRACE(("ACCESS name=%s, pResOut=%p, *pResOut=%d, rc=SQLITE_OK\n",
+           zFilename, pResOut, *pResOut));
+  return SQLITE_OK;
+}
+
+/*
+** Returns non-zero if the specified path name starts with a drive letter
+** followed by a colon character.
+*/
+static BOOL winIsDriveLetterAndColon(
+  const char *zPathname
+){
+  return ( sqlite3Isalpha(zPathname[0]) && zPathname[1]==':' );
+}
+
+/*
+** Returns non-zero if the specified path name should be used verbatim.  If
+** non-zero is returned from this function, the calling function must simply
+** use the provided path name verbatim -OR- resolve it into a full path name
+** using the GetFullPathName Win32 API function (if available).
+*/
+static BOOL winIsVerbatimPathname(
+  const char *zPathname
+){
+  /*
+  ** If the path name starts with a forward slash or a backslash, it is either
+  ** a legal UNC name, a volume relative path, or an absolute path name in the
+  ** "Unix" format on Windows.  There is no easy way to differentiate between
+  ** the final two cases; therefore, we return the safer return value of TRUE
+  ** so that callers of this function will simply use it verbatim.
+  */
+  if ( winIsDirSep(zPathname[0]) ){
+    return TRUE;
+  }
+
+  /*
+  ** If the path name starts with a letter and a colon it is either a volume
+  ** relative path or an absolute path.  Callers of this function must not
+  ** attempt to treat it as a relative path name (i.e. they should simply use
+  ** it verbatim).
+  */
+  if ( winIsDriveLetterAndColon(zPathname) ){
+    return TRUE;
+  }
+
+  /*
+  ** If we get to this point, the path name should almost certainly be a purely
+  ** relative one (i.e. not a UNC name, not absolute, and not volume relative).
+  */
+  return FALSE;
+}
+
+/*
+** Turn a relative pathname into a full pathname.  Write the full
+** pathname into zOut[].  zOut[] will be at least pVfs->mxPathname
+** bytes in size.
+*/
+static int winFullPathname(
+  sqlite3_vfs *pVfs,            /* Pointer to vfs object */
+  const char *zRelative,        /* Possibly relative input path */
+  int nFull,                    /* Size of output buffer in bytes */
+  char *zFull                   /* Output buffer */
+){
+#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT && !defined(__CYGWIN__)
+  DWORD nByte;
+  void *zConverted;
+  char *zOut;
+#endif
+
+  /* If this path name begins with "/X:", where "X" is any alphabetic
+  ** character, discard the initial "/" from the pathname.
+  */
+  if( zRelative[0]=='/' && winIsDriveLetterAndColon(zRelative+1) ){
+    zRelative++;
+  }
+
+#if defined(__CYGWIN__)
+  SimulateIOError( return SQLITE_ERROR );
+  UNUSED_PARAMETER(nFull);
+  assert( nFull>=pVfs->mxPathname );
+  if ( sqlite3_data_directory && !winIsVerbatimPathname(zRelative) ){
+    /*
+    ** NOTE: We are dealing with a relative path name and the data
+    **       directory has been set.  Therefore, use it as the basis
+    **       for converting the relative path name to an absolute
+    **       one by prepending the data directory and a slash.
+    */
+    char *zOut = sqlite3MallocZero( pVfs->mxPathname+1 );
+    if( !zOut ){
+      return SQLITE_IOERR_NOMEM_BKPT;
+    }
+    if( cygwin_conv_path(
+            (osIsNT() ? CCP_POSIX_TO_WIN_W : CCP_POSIX_TO_WIN_A) |
+            CCP_RELATIVE, zRelative, zOut, pVfs->mxPathname+1)<0 ){
+      sqlite3_free(zOut);
+      return winLogError(SQLITE_CANTOPEN_CONVPATH, (DWORD)errno,
+                         "winFullPathname1", zRelative);
+    }else{
+      char *zUtf8 = winConvertToUtf8Filename(zOut);
+      if( !zUtf8 ){
+        sqlite3_free(zOut);
+        return SQLITE_IOERR_NOMEM_BKPT;
+      }
+      sqlite3_snprintf(MIN(nFull, pVfs->mxPathname), zFull, "%s%c%s",
+                       sqlite3_data_directory, winGetDirSep(), zUtf8);
+      sqlite3_free(zUtf8);
+      sqlite3_free(zOut);
+    }
+  }else{
+    char *zOut = sqlite3MallocZero( pVfs->mxPathname+1 );
+    if( !zOut ){
+      return SQLITE_IOERR_NOMEM_BKPT;
+    }
+    if( cygwin_conv_path(
+            (osIsNT() ? CCP_POSIX_TO_WIN_W : CCP_POSIX_TO_WIN_A),
+            zRelative, zOut, pVfs->mxPathname+1)<0 ){
+      sqlite3_free(zOut);
+      return winLogError(SQLITE_CANTOPEN_CONVPATH, (DWORD)errno,
+                         "winFullPathname2", zRelative);
+    }else{
+      char *zUtf8 = winConvertToUtf8Filename(zOut);
+      if( !zUtf8 ){
+        sqlite3_free(zOut);
+        return SQLITE_IOERR_NOMEM_BKPT;
+      }
+      sqlite3_snprintf(MIN(nFull, pVfs->mxPathname), zFull, "%s", zUtf8);
+      sqlite3_free(zUtf8);
+      sqlite3_free(zOut);
+    }
+  }
+  return SQLITE_OK;
+#endif
+
+#if (SQLITE_OS_WINCE || SQLITE_OS_WINRT) && !defined(__CYGWIN__)
+  SimulateIOError( return SQLITE_ERROR );
+  /* WinCE has no concept of a relative pathname, or so I am told. */
+  /* WinRT has no way to convert a relative path to an absolute one. */
+  if ( sqlite3_data_directory && !winIsVerbatimPathname(zRelative) ){
+    /*
+    ** NOTE: We are dealing with a relative path name and the data
+    **       directory has been set.  Therefore, use it as the basis
+    **       for converting the relative path name to an absolute
+    **       one by prepending the data directory and a backslash.
+    */
+    sqlite3_snprintf(MIN(nFull, pVfs->mxPathname), zFull, "%s%c%s",
+                     sqlite3_data_directory, winGetDirSep(), zRelative);
+  }else{
+    sqlite3_snprintf(MIN(nFull, pVfs->mxPathname), zFull, "%s", zRelative);
+  }
+  return SQLITE_OK;
+#endif
+
+#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT && !defined(__CYGWIN__)
+  /* It's odd to simulate an io-error here, but really this is just
+  ** using the io-error infrastructure to test that SQLite handles this
+  ** function failing. This function could fail if, for example, the
+  ** current working directory has been unlinked.
+  */
+  SimulateIOError( return SQLITE_ERROR );
+  if ( sqlite3_data_directory && !winIsVerbatimPathname(zRelative) ){
+    /*
+    ** NOTE: We are dealing with a relative path name and the data
+    **       directory has been set.  Therefore, use it as the basis
+    **       for converting the relative path name to an absolute
+    **       one by prepending the data directory and a backslash.
+    */
+    sqlite3_snprintf(MIN(nFull, pVfs->mxPathname), zFull, "%s%c%s",
+                     sqlite3_data_directory, winGetDirSep(), zRelative);
+    return SQLITE_OK;
+  }
+  zConverted = winConvertFromUtf8Filename(zRelative);
+  if( zConverted==0 ){
+    return SQLITE_IOERR_NOMEM_BKPT;
+  }
+  if( osIsNT() ){
+    LPWSTR zTemp;
+    nByte = osGetFullPathNameW((LPCWSTR)zConverted, 0, 0, 0);
+    if( nByte==0 ){
+      sqlite3_free(zConverted);
+      return winLogError(SQLITE_CANTOPEN_FULLPATH, osGetLastError(),
+                         "winFullPathname1", zRelative);
+    }
+    nByte += 3;
+    zTemp = sqlite3MallocZero( nByte*sizeof(zTemp[0]) );
+    if( zTemp==0 ){
+      sqlite3_free(zConverted);
+      return SQLITE_IOERR_NOMEM_BKPT;
+    }
+    nByte = osGetFullPathNameW((LPCWSTR)zConverted, nByte, zTemp, 0);
+    if( nByte==0 ){
+      sqlite3_free(zConverted);
+      sqlite3_free(zTemp);
+      return winLogError(SQLITE_CANTOPEN_FULLPATH, osGetLastError(),
+                         "winFullPathname2", zRelative);
+    }
+    sqlite3_free(zConverted);
+    zOut = winUnicodeToUtf8(zTemp);
+    sqlite3_free(zTemp);
+  }
+#ifdef SQLITE_WIN32_HAS_ANSI
+  else{
+    char *zTemp;
+    nByte = osGetFullPathNameA((char*)zConverted, 0, 0, 0);
+    if( nByte==0 ){
+      sqlite3_free(zConverted);
+      return winLogError(SQLITE_CANTOPEN_FULLPATH, osGetLastError(),
+                         "winFullPathname3", zRelative);
+    }
+    nByte += 3;
+    zTemp = sqlite3MallocZero( nByte*sizeof(zTemp[0]) );
+    if( zTemp==0 ){
+      sqlite3_free(zConverted);
+      return SQLITE_IOERR_NOMEM_BKPT;
+    }
+    nByte = osGetFullPathNameA((char*)zConverted, nByte, zTemp, 0);
+    if( nByte==0 ){
+      sqlite3_free(zConverted);
+      sqlite3_free(zTemp);
+      return winLogError(SQLITE_CANTOPEN_FULLPATH, osGetLastError(),
+                         "winFullPathname4", zRelative);
+    }
+    sqlite3_free(zConverted);
+    zOut = winMbcsToUtf8(zTemp, osAreFileApisANSI());
+    sqlite3_free(zTemp);
+  }
+#endif
+  if( zOut ){
+    sqlite3_snprintf(MIN(nFull, pVfs->mxPathname), zFull, "%s", zOut);
+    sqlite3_free(zOut);
+    return SQLITE_OK;
+  }else{
+    return SQLITE_IOERR_NOMEM_BKPT;
+  }
+#endif
+}
+
+#ifndef SQLITE_OMIT_LOAD_EXTENSION
+/*
+** Interfaces for opening a shared library, finding entry points
+** within the shared library, and closing the shared library.
+*/
+static void *winDlOpen(sqlite3_vfs *pVfs, const char *zFilename){
+  HANDLE h;
+#if defined(__CYGWIN__)
+  int nFull = pVfs->mxPathname+1;
+  char *zFull = sqlite3MallocZero( nFull );
+  void *zConverted = 0;
+  if( zFull==0 ){
+    OSTRACE(("DLOPEN name=%s, handle=%p\n", zFilename, (void*)0));
+    return 0;
+  }
+  if( winFullPathname(pVfs, zFilename, nFull, zFull)!=SQLITE_OK ){
+    sqlite3_free(zFull);
+    OSTRACE(("DLOPEN name=%s, handle=%p\n", zFilename, (void*)0));
+    return 0;
+  }
+  zConverted = winConvertFromUtf8Filename(zFull);
+  sqlite3_free(zFull);
+#else
+  void *zConverted = winConvertFromUtf8Filename(zFilename);
+  UNUSED_PARAMETER(pVfs);
+#endif
+  if( zConverted==0 ){
+    OSTRACE(("DLOPEN name=%s, handle=%p\n", zFilename, (void*)0));
+    return 0;
+  }
+  if( osIsNT() ){
+#if SQLITE_OS_WINRT
+    h = osLoadPackagedLibrary((LPCWSTR)zConverted, 0);
+#else
+    h = osLoadLibraryW((LPCWSTR)zConverted);
+#endif
+  }
+#ifdef SQLITE_WIN32_HAS_ANSI
+  else{
+    h = osLoadLibraryA((char*)zConverted);
+  }
+#endif
+  OSTRACE(("DLOPEN name=%s, handle=%p\n", zFilename, (void*)h));
+  sqlite3_free(zConverted);
+  return (void*)h;
+}
+static void winDlError(sqlite3_vfs *pVfs, int nBuf, char *zBufOut){
+  UNUSED_PARAMETER(pVfs);
+  winGetLastErrorMsg(osGetLastError(), nBuf, zBufOut);
+}
+static void (*winDlSym(sqlite3_vfs *pVfs,void *pH,const char *zSym))(void){
+  FARPROC proc;
+  UNUSED_PARAMETER(pVfs);
+  proc = osGetProcAddressA((HANDLE)pH, zSym);
+  OSTRACE(("DLSYM handle=%p, symbol=%s, address=%p\n",
+           (void*)pH, zSym, (void*)proc));
+  return (void(*)(void))proc;
+}
+static void winDlClose(sqlite3_vfs *pVfs, void *pHandle){
+  UNUSED_PARAMETER(pVfs);
+  osFreeLibrary((HANDLE)pHandle);
+  OSTRACE(("DLCLOSE handle=%p\n", (void*)pHandle));
+}
+#else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */
+  #define winDlOpen  0
+  #define winDlError 0
+  #define winDlSym   0
+  #define winDlClose 0
+#endif
+
+/* State information for the randomness gatherer. */
+typedef struct EntropyGatherer EntropyGatherer;
+struct EntropyGatherer {
+  unsigned char *a;   /* Gather entropy into this buffer */
+  int na;             /* Size of a[] in bytes */
+  int i;              /* XOR next input into a[i] */
+  int nXor;           /* Number of XOR operations done */
+};
+
+#if !defined(SQLITE_TEST) && !defined(SQLITE_OMIT_RANDOMNESS)
+/* Mix sz bytes of entropy into p. */
+static void xorMemory(EntropyGatherer *p, unsigned char *x, int sz){
+  int j, k;
+  for(j=0, k=p->i; j<sz; j++){
+    p->a[k++] ^= x[j];
+    if( k>=p->na ) k = 0;
+  }
+  p->i = k;
+  p->nXor += sz;
+}
+#endif /* !defined(SQLITE_TEST) && !defined(SQLITE_OMIT_RANDOMNESS) */
+
+/*
+** Write up to nBuf bytes of randomness into zBuf.
+*/
+static int winRandomness(sqlite3_vfs *pVfs, int nBuf, char *zBuf){
+#if defined(SQLITE_TEST) || defined(SQLITE_OMIT_RANDOMNESS)
+  UNUSED_PARAMETER(pVfs);
+  memset(zBuf, 0, nBuf);
+  return nBuf;
+#else
+  EntropyGatherer e;
+  UNUSED_PARAMETER(pVfs);
+  memset(zBuf, 0, nBuf);
+#if defined(_MSC_VER) && _MSC_VER>=1400 && !SQLITE_OS_WINCE
+  rand_s((unsigned int*)zBuf); /* rand_s() is not available with MinGW */
+#endif /* defined(_MSC_VER) && _MSC_VER>=1400 */
+  e.a = (unsigned char*)zBuf;
+  e.na = nBuf;
+  e.nXor = 0;
+  e.i = 0;
+  {
+    SYSTEMTIME x;
+    osGetSystemTime(&x);
+    xorMemory(&e, (unsigned char*)&x, sizeof(SYSTEMTIME));
+  }
+  {
+    DWORD pid = osGetCurrentProcessId();
+    xorMemory(&e, (unsigned char*)&pid, sizeof(DWORD));
+  }
+#if SQLITE_OS_WINRT
+  {
+    ULONGLONG cnt = osGetTickCount64();
+    xorMemory(&e, (unsigned char*)&cnt, sizeof(ULONGLONG));
+  }
+#else
+  {
+    DWORD cnt = osGetTickCount();
+    xorMemory(&e, (unsigned char*)&cnt, sizeof(DWORD));
+  }
+#endif /* SQLITE_OS_WINRT */
+  {
+    LARGE_INTEGER i;
+    osQueryPerformanceCounter(&i);
+    xorMemory(&e, (unsigned char*)&i, sizeof(LARGE_INTEGER));
+  }
+#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT && SQLITE_WIN32_USE_UUID
+  {
+    UUID id;
+    memset(&id, 0, sizeof(UUID));
+    osUuidCreate(&id);
+    xorMemory(&e, (unsigned char*)&id, sizeof(UUID));
+    memset(&id, 0, sizeof(UUID));
+    osUuidCreateSequential(&id);
+    xorMemory(&e, (unsigned char*)&id, sizeof(UUID));
+  }
+#endif /* !SQLITE_OS_WINCE && !SQLITE_OS_WINRT && SQLITE_WIN32_USE_UUID */
+  return e.nXor>nBuf ? nBuf : e.nXor;
+#endif /* defined(SQLITE_TEST) || defined(SQLITE_OMIT_RANDOMNESS) */
+}
+
+
+/*
+** Sleep for a little while.  Return the amount of time slept.
+*/
+static int winSleep(sqlite3_vfs *pVfs, int microsec){
+  sqlite3_win32_sleep((microsec+999)/1000);
+  UNUSED_PARAMETER(pVfs);
+  return ((microsec+999)/1000)*1000;
+}
+
+/*
+** The following variable, if set to a non-zero value, is interpreted as
+** the number of seconds since 1970 and is used to set the result of
+** sqlite3OsCurrentTime() during testing.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_current_time = 0;  /* Fake system time in seconds since 1970. */
+#endif
+
+/*
+** Find the current time (in Universal Coordinated Time).  Write into *piNow
+** the current time and date as a Julian Day number times 86_400_000.  In
+** other words, write into *piNow the number of milliseconds since the Julian
+** epoch of noon in Greenwich on November 24, 4714 B.C according to the
+** proleptic Gregorian calendar.
+**
+** On success, return SQLITE_OK.  Return SQLITE_ERROR if the time and date
+** cannot be found.
+*/
+static int winCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *piNow){
+  /* FILETIME structure is a 64-bit value representing the number of
+     100-nanosecond intervals since January 1, 1601 (= JD 2305813.5).
+  */
+  FILETIME ft;
+  static const sqlite3_int64 winFiletimeEpoch = 23058135*(sqlite3_int64)8640000;
+#ifdef SQLITE_TEST
+  static const sqlite3_int64 unixEpoch = 24405875*(sqlite3_int64)8640000;
+#endif
+  /* 2^32 - to avoid use of LL and warnings in gcc */
+  static const sqlite3_int64 max32BitValue =
+      (sqlite3_int64)2000000000 + (sqlite3_int64)2000000000 +
+      (sqlite3_int64)294967296;
+
+#if SQLITE_OS_WINCE
+  SYSTEMTIME time;
+  osGetSystemTime(&time);
+  /* if SystemTimeToFileTime() fails, it returns zero. */
+  if (!osSystemTimeToFileTime(&time,&ft)){
+    return SQLITE_ERROR;
+  }
+#else
+  osGetSystemTimeAsFileTime( &ft );
+#endif
+
+  *piNow = winFiletimeEpoch +
+            ((((sqlite3_int64)ft.dwHighDateTime)*max32BitValue) +
+               (sqlite3_int64)ft.dwLowDateTime)/(sqlite3_int64)10000;
+
+#ifdef SQLITE_TEST
+  if( sqlite3_current_time ){
+    *piNow = 1000*(sqlite3_int64)sqlite3_current_time + unixEpoch;
+  }
+#endif
+  UNUSED_PARAMETER(pVfs);
+  return SQLITE_OK;
+}
+
+/*
+** Find the current time (in Universal Coordinated Time).  Write the
+** current time and date as a Julian Day number into *prNow and
+** return 0.  Return 1 if the time and date cannot be found.
+*/
+static int winCurrentTime(sqlite3_vfs *pVfs, double *prNow){
+  int rc;
+  sqlite3_int64 i;
+  rc = winCurrentTimeInt64(pVfs, &i);
+  if( !rc ){
+    *prNow = i/86400000.0;
+  }
+  return rc;
+}
+
+/*
+** The idea is that this function works like a combination of
+** GetLastError() and FormatMessage() on Windows (or errno and
+** strerror_r() on Unix). After an error is returned by an OS
+** function, SQLite calls this function with zBuf pointing to
+** a buffer of nBuf bytes. The OS layer should populate the
+** buffer with a nul-terminated UTF-8 encoded error message
+** describing the last IO error to have occurred within the calling
+** thread.
+**
+** If the error message is too large for the supplied buffer,
+** it should be truncated. The return value of xGetLastError
+** is zero if the error message fits in the buffer, or non-zero
+** otherwise (if the message was truncated). If non-zero is returned,
+** then it is not necessary to include the nul-terminator character
+** in the output buffer.
+**
+** Not supplying an error message will have no adverse effect
+** on SQLite. It is fine to have an implementation that never
+** returns an error message:
+**
+**   int xGetLastError(sqlite3_vfs *pVfs, int nBuf, char *zBuf){
+**     assert(zBuf[0]=='\0');
+**     return 0;
+**   }
+**
+** However if an error message is supplied, it will be incorporated
+** by sqlite into the error message available to the user using
+** sqlite3_errmsg(), possibly making IO errors easier to debug.
+*/
+static int winGetLastError(sqlite3_vfs *pVfs, int nBuf, char *zBuf){
+  DWORD e = osGetLastError();
+  UNUSED_PARAMETER(pVfs);
+  if( nBuf>0 ) winGetLastErrorMsg(e, nBuf, zBuf);
+  return e;
+}
+
+/*
+** Initialize and deinitialize the operating system interface.
+*/
+SQLITE_API int sqlite3_os_init(void){
+  static sqlite3_vfs winVfs = {
+    3,                     /* iVersion */
+    sizeof(winFile),       /* szOsFile */
+    SQLITE_WIN32_MAX_PATH_BYTES, /* mxPathname */
+    0,                     /* pNext */
+    "win32",               /* zName */
+    &winAppData,           /* pAppData */
+    winOpen,               /* xOpen */
+    winDelete,             /* xDelete */
+    winAccess,             /* xAccess */
+    winFullPathname,       /* xFullPathname */
+    winDlOpen,             /* xDlOpen */
+    winDlError,            /* xDlError */
+    winDlSym,              /* xDlSym */
+    winDlClose,            /* xDlClose */
+    winRandomness,         /* xRandomness */
+    winSleep,              /* xSleep */
+    winCurrentTime,        /* xCurrentTime */
+    winGetLastError,       /* xGetLastError */
+    winCurrentTimeInt64,   /* xCurrentTimeInt64 */
+    winSetSystemCall,      /* xSetSystemCall */
+    winGetSystemCall,      /* xGetSystemCall */
+    winNextSystemCall,     /* xNextSystemCall */
+  };
+#if defined(SQLITE_WIN32_HAS_WIDE)
+  static sqlite3_vfs winLongPathVfs = {
+    3,                     /* iVersion */
+    sizeof(winFile),       /* szOsFile */
+    SQLITE_WINNT_MAX_PATH_BYTES, /* mxPathname */
+    0,                     /* pNext */
+    "win32-longpath",      /* zName */
+    &winAppData,           /* pAppData */
+    winOpen,               /* xOpen */
+    winDelete,             /* xDelete */
+    winAccess,             /* xAccess */
+    winFullPathname,       /* xFullPathname */
+    winDlOpen,             /* xDlOpen */
+    winDlError,            /* xDlError */
+    winDlSym,              /* xDlSym */
+    winDlClose,            /* xDlClose */
+    winRandomness,         /* xRandomness */
+    winSleep,              /* xSleep */
+    winCurrentTime,        /* xCurrentTime */
+    winGetLastError,       /* xGetLastError */
+    winCurrentTimeInt64,   /* xCurrentTimeInt64 */
+    winSetSystemCall,      /* xSetSystemCall */
+    winGetSystemCall,      /* xGetSystemCall */
+    winNextSystemCall,     /* xNextSystemCall */
+  };
+#endif
+  static sqlite3_vfs winNolockVfs = {
+    3,                     /* iVersion */
+    sizeof(winFile),       /* szOsFile */
+    SQLITE_WIN32_MAX_PATH_BYTES, /* mxPathname */
+    0,                     /* pNext */
+    "win32-none",          /* zName */
+    &winNolockAppData,     /* pAppData */
+    winOpen,               /* xOpen */
+    winDelete,             /* xDelete */
+    winAccess,             /* xAccess */
+    winFullPathname,       /* xFullPathname */
+    winDlOpen,             /* xDlOpen */
+    winDlError,            /* xDlError */
+    winDlSym,              /* xDlSym */
+    winDlClose,            /* xDlClose */
+    winRandomness,         /* xRandomness */
+    winSleep,              /* xSleep */
+    winCurrentTime,        /* xCurrentTime */
+    winGetLastError,       /* xGetLastError */
+    winCurrentTimeInt64,   /* xCurrentTimeInt64 */
+    winSetSystemCall,      /* xSetSystemCall */
+    winGetSystemCall,      /* xGetSystemCall */
+    winNextSystemCall,     /* xNextSystemCall */
+  };
+#if defined(SQLITE_WIN32_HAS_WIDE)
+  static sqlite3_vfs winLongPathNolockVfs = {
+    3,                     /* iVersion */
+    sizeof(winFile),       /* szOsFile */
+    SQLITE_WINNT_MAX_PATH_BYTES, /* mxPathname */
+    0,                     /* pNext */
+    "win32-longpath-none", /* zName */
+    &winNolockAppData,     /* pAppData */
+    winOpen,               /* xOpen */
+    winDelete,             /* xDelete */
+    winAccess,             /* xAccess */
+    winFullPathname,       /* xFullPathname */
+    winDlOpen,             /* xDlOpen */
+    winDlError,            /* xDlError */
+    winDlSym,              /* xDlSym */
+    winDlClose,            /* xDlClose */
+    winRandomness,         /* xRandomness */
+    winSleep,              /* xSleep */
+    winCurrentTime,        /* xCurrentTime */
+    winGetLastError,       /* xGetLastError */
+    winCurrentTimeInt64,   /* xCurrentTimeInt64 */
+    winSetSystemCall,      /* xSetSystemCall */
+    winGetSystemCall,      /* xGetSystemCall */
+    winNextSystemCall,     /* xNextSystemCall */
+  };
+#endif
+
+  /* Double-check that the aSyscall[] array has been constructed
+  ** correctly.  See ticket [bb3a86e890c8e96ab] */
+  assert( ArraySize(aSyscall)==80 );
+
+  /* get memory map allocation granularity */
+  memset(&winSysInfo, 0, sizeof(SYSTEM_INFO));
+#if SQLITE_OS_WINRT
+  osGetNativeSystemInfo(&winSysInfo);
+#else
+  osGetSystemInfo(&winSysInfo);
+#endif
+  assert( winSysInfo.dwAllocationGranularity>0 );
+  assert( winSysInfo.dwPageSize>0 );
+
+  sqlite3_vfs_register(&winVfs, 1);
+
+#if defined(SQLITE_WIN32_HAS_WIDE)
+  sqlite3_vfs_register(&winLongPathVfs, 0);
+#endif
+
+  sqlite3_vfs_register(&winNolockVfs, 0);
+
+#if defined(SQLITE_WIN32_HAS_WIDE)
+  sqlite3_vfs_register(&winLongPathNolockVfs, 0);
+#endif
+
+  return SQLITE_OK;
+}
+
+SQLITE_API int sqlite3_os_end(void){
+#if SQLITE_OS_WINRT
+  if( sleepObj!=NULL ){
+    osCloseHandle(sleepObj);
+    sleepObj = NULL;
+  }
+#endif
+  return SQLITE_OK;
+}
+
+#endif /* SQLITE_OS_WIN */
+
+/************** End of os_win.c **********************************************/
+/************** Begin file bitvec.c ******************************************/
+/*
+** 2008 February 16
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file implements an object that represents a fixed-length
+** bitmap.  Bits are numbered starting with 1.
+**
+** A bitmap is used to record which pages of a database file have been
+** journalled during a transaction, or which pages have the "dont-write"
+** property.  Usually only a few pages are meet either condition.
+** So the bitmap is usually sparse and has low cardinality.
+** But sometimes (for example when during a DROP of a large table) most
+** or all of the pages in a database can get journalled.  In those cases, 
+** the bitmap becomes dense with high cardinality.  The algorithm needs 
+** to handle both cases well.
+**
+** The size of the bitmap is fixed when the object is created.
+**
+** All bits are clear when the bitmap is created.  Individual bits
+** may be set or cleared one at a time.
+**
+** Test operations are about 100 times more common that set operations.
+** Clear operations are exceedingly rare.  There are usually between
+** 5 and 500 set operations per Bitvec object, though the number of sets can
+** sometimes grow into tens of thousands or larger.  The size of the
+** Bitvec object is the number of pages in the database file at the
+** start of a transaction, and is thus usually less than a few thousand,
+** but can be as large as 2 billion for a really big database.
+*/
+/* #include "sqliteInt.h" */
+
+/* Size of the Bitvec structure in bytes. */
+#define BITVEC_SZ        512
+
+/* Round the union size down to the nearest pointer boundary, since that's how 
+** it will be aligned within the Bitvec struct. */
+#define BITVEC_USIZE \
+    (((BITVEC_SZ-(3*sizeof(u32)))/sizeof(Bitvec*))*sizeof(Bitvec*))
+
+/* Type of the array "element" for the bitmap representation. 
+** Should be a power of 2, and ideally, evenly divide into BITVEC_USIZE. 
+** Setting this to the "natural word" size of your CPU may improve
+** performance. */
+#define BITVEC_TELEM     u8
+/* Size, in bits, of the bitmap element. */
+#define BITVEC_SZELEM    8
+/* Number of elements in a bitmap array. */
+#define BITVEC_NELEM     (BITVEC_USIZE/sizeof(BITVEC_TELEM))
+/* Number of bits in the bitmap array. */
+#define BITVEC_NBIT      (BITVEC_NELEM*BITVEC_SZELEM)
+
+/* Number of u32 values in hash table. */
+#define BITVEC_NINT      (BITVEC_USIZE/sizeof(u32))
+/* Maximum number of entries in hash table before 
+** sub-dividing and re-hashing. */
+#define BITVEC_MXHASH    (BITVEC_NINT/2)
+/* Hashing function for the aHash representation.
+** Empirical testing showed that the *37 multiplier 
+** (an arbitrary prime)in the hash function provided 
+** no fewer collisions than the no-op *1. */
+#define BITVEC_HASH(X)   (((X)*1)%BITVEC_NINT)
+
+#define BITVEC_NPTR      (BITVEC_USIZE/sizeof(Bitvec *))
+
+
+/*
+** A bitmap is an instance of the following structure.
+**
+** This bitmap records the existence of zero or more bits
+** with values between 1 and iSize, inclusive.
+**
+** There are three possible representations of the bitmap.
+** If iSize<=BITVEC_NBIT, then Bitvec.u.aBitmap[] is a straight
+** bitmap.  The least significant bit is bit 1.
+**
+** If iSize>BITVEC_NBIT and iDivisor==0 then Bitvec.u.aHash[] is
+** a hash table that will hold up to BITVEC_MXHASH distinct values.
+**
+** Otherwise, the value i is redirected into one of BITVEC_NPTR
+** sub-bitmaps pointed to by Bitvec.u.apSub[].  Each subbitmap
+** handles up to iDivisor separate values of i.  apSub[0] holds
+** values between 1 and iDivisor.  apSub[1] holds values between
+** iDivisor+1 and 2*iDivisor.  apSub[N] holds values between
+** N*iDivisor+1 and (N+1)*iDivisor.  Each subbitmap is normalized
+** to hold deal with values between 1 and iDivisor.
+*/
+struct Bitvec {
+  u32 iSize;      /* Maximum bit index.  Max iSize is 4,294,967,296. */
+  u32 nSet;       /* Number of bits that are set - only valid for aHash
+                  ** element.  Max is BITVEC_NINT.  For BITVEC_SZ of 512,
+                  ** this would be 125. */
+  u32 iDivisor;   /* Number of bits handled by each apSub[] entry. */
+                  /* Should >=0 for apSub element. */
+                  /* Max iDivisor is max(u32) / BITVEC_NPTR + 1.  */
+                  /* For a BITVEC_SZ of 512, this would be 34,359,739. */
+  union {
+    BITVEC_TELEM aBitmap[BITVEC_NELEM];    /* Bitmap representation */
+    u32 aHash[BITVEC_NINT];      /* Hash table representation */
+    Bitvec *apSub[BITVEC_NPTR];  /* Recursive representation */
+  } u;
+};
+
+/*
+** Create a new bitmap object able to handle bits between 0 and iSize,
+** inclusive.  Return a pointer to the new object.  Return NULL if 
+** malloc fails.
+*/
+SQLITE_PRIVATE Bitvec *sqlite3BitvecCreate(u32 iSize){
+  Bitvec *p;
+  assert( sizeof(*p)==BITVEC_SZ );
+  p = sqlite3MallocZero( sizeof(*p) );
+  if( p ){
+    p->iSize = iSize;
+  }
+  return p;
+}
+
+/*
+** Check to see if the i-th bit is set.  Return true or false.
+** If p is NULL (if the bitmap has not been created) or if
+** i is out of range, then return false.
+*/
+SQLITE_PRIVATE int sqlite3BitvecTestNotNull(Bitvec *p, u32 i){
+  assert( p!=0 );
+  i--;
+  if( i>=p->iSize ) return 0;
+  while( p->iDivisor ){
+    u32 bin = i/p->iDivisor;
+    i = i%p->iDivisor;
+    p = p->u.apSub[bin];
+    if (!p) {
+      return 0;
+    }
+  }
+  if( p->iSize<=BITVEC_NBIT ){
+    return (p->u.aBitmap[i/BITVEC_SZELEM] & (1<<(i&(BITVEC_SZELEM-1))))!=0;
+  } else{
+    u32 h = BITVEC_HASH(i++);
+    while( p->u.aHash[h] ){
+      if( p->u.aHash[h]==i ) return 1;
+      h = (h+1) % BITVEC_NINT;
+    }
+    return 0;
+  }
+}
+SQLITE_PRIVATE int sqlite3BitvecTest(Bitvec *p, u32 i){
+  return p!=0 && sqlite3BitvecTestNotNull(p,i);
+}
+
+/*
+** Set the i-th bit.  Return 0 on success and an error code if
+** anything goes wrong.
+**
+** This routine might cause sub-bitmaps to be allocated.  Failing
+** to get the memory needed to hold the sub-bitmap is the only
+** that can go wrong with an insert, assuming p and i are valid.
+**
+** The calling function must ensure that p is a valid Bitvec object
+** and that the value for "i" is within range of the Bitvec object.
+** Otherwise the behavior is undefined.
+*/
+SQLITE_PRIVATE int sqlite3BitvecSet(Bitvec *p, u32 i){
+  u32 h;
+  if( p==0 ) return SQLITE_OK;
+  assert( i>0 );
+  assert( i<=p->iSize );
+  i--;
+  while((p->iSize > BITVEC_NBIT) && p->iDivisor) {
+    u32 bin = i/p->iDivisor;
+    i = i%p->iDivisor;
+    if( p->u.apSub[bin]==0 ){
+      p->u.apSub[bin] = sqlite3BitvecCreate( p->iDivisor );
+      if( p->u.apSub[bin]==0 ) return SQLITE_NOMEM_BKPT;
+    }
+    p = p->u.apSub[bin];
+  }
+  if( p->iSize<=BITVEC_NBIT ){
+    p->u.aBitmap[i/BITVEC_SZELEM] |= 1 << (i&(BITVEC_SZELEM-1));
+    return SQLITE_OK;
+  }
+  h = BITVEC_HASH(i++);
+  /* if there wasn't a hash collision, and this doesn't */
+  /* completely fill the hash, then just add it without */
+  /* worring about sub-dividing and re-hashing. */
+  if( !p->u.aHash[h] ){
+    if (p->nSet<(BITVEC_NINT-1)) {
+      goto bitvec_set_end;
+    } else {
+      goto bitvec_set_rehash;
+    }
+  }
+  /* there was a collision, check to see if it's already */
+  /* in hash, if not, try to find a spot for it */
+  do {
+    if( p->u.aHash[h]==i ) return SQLITE_OK;
+    h++;
+    if( h>=BITVEC_NINT ) h = 0;
+  } while( p->u.aHash[h] );
+  /* we didn't find it in the hash.  h points to the first */
+  /* available free spot. check to see if this is going to */
+  /* make our hash too "full".  */
+bitvec_set_rehash:
+  if( p->nSet>=BITVEC_MXHASH ){
+    unsigned int j;
+    int rc;
+    u32 *aiValues = sqlite3StackAllocRaw(0, sizeof(p->u.aHash));
+    if( aiValues==0 ){
+      return SQLITE_NOMEM_BKPT;
+    }else{
+      memcpy(aiValues, p->u.aHash, sizeof(p->u.aHash));
+      memset(p->u.apSub, 0, sizeof(p->u.apSub));
+      p->iDivisor = (p->iSize + BITVEC_NPTR - 1)/BITVEC_NPTR;
+      rc = sqlite3BitvecSet(p, i);
+      for(j=0; j<BITVEC_NINT; j++){
+        if( aiValues[j] ) rc |= sqlite3BitvecSet(p, aiValues[j]);
+      }
+      sqlite3StackFree(0, aiValues);
+      return rc;
+    }
+  }
+bitvec_set_end:
+  p->nSet++;
+  p->u.aHash[h] = i;
+  return SQLITE_OK;
+}
+
+/*
+** Clear the i-th bit.
+**
+** pBuf must be a pointer to at least BITVEC_SZ bytes of temporary storage
+** that BitvecClear can use to rebuilt its hash table.
+*/
+SQLITE_PRIVATE void sqlite3BitvecClear(Bitvec *p, u32 i, void *pBuf){
+  if( p==0 ) return;
+  assert( i>0 );
+  i--;
+  while( p->iDivisor ){
+    u32 bin = i/p->iDivisor;
+    i = i%p->iDivisor;
+    p = p->u.apSub[bin];
+    if (!p) {
+      return;
+    }
+  }
+  if( p->iSize<=BITVEC_NBIT ){
+    p->u.aBitmap[i/BITVEC_SZELEM] &= ~(1 << (i&(BITVEC_SZELEM-1)));
+  }else{
+    unsigned int j;
+    u32 *aiValues = pBuf;
+    memcpy(aiValues, p->u.aHash, sizeof(p->u.aHash));
+    memset(p->u.aHash, 0, sizeof(p->u.aHash));
+    p->nSet = 0;
+    for(j=0; j<BITVEC_NINT; j++){
+      if( aiValues[j] && aiValues[j]!=(i+1) ){
+        u32 h = BITVEC_HASH(aiValues[j]-1);
+        p->nSet++;
+        while( p->u.aHash[h] ){
+          h++;
+          if( h>=BITVEC_NINT ) h = 0;
+        }
+        p->u.aHash[h] = aiValues[j];
+      }
+    }
+  }
+}
+
+/*
+** Destroy a bitmap object.  Reclaim all memory used.
+*/
+SQLITE_PRIVATE void sqlite3BitvecDestroy(Bitvec *p){
+  if( p==0 ) return;
+  if( p->iDivisor ){
+    unsigned int i;
+    for(i=0; i<BITVEC_NPTR; i++){
+      sqlite3BitvecDestroy(p->u.apSub[i]);
+    }
+  }
+  sqlite3_free(p);
+}
+
+/*
+** Return the value of the iSize parameter specified when Bitvec *p
+** was created.
+*/
+SQLITE_PRIVATE u32 sqlite3BitvecSize(Bitvec *p){
+  return p->iSize;
+}
+
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+/*
+** Let V[] be an array of unsigned characters sufficient to hold
+** up to N bits.  Let I be an integer between 0 and N.  0<=I<N.
+** Then the following macros can be used to set, clear, or test
+** individual bits within V.
+*/
+#define SETBIT(V,I)      V[I>>3] |= (1<<(I&7))
+#define CLEARBIT(V,I)    V[I>>3] &= ~(1<<(I&7))
+#define TESTBIT(V,I)     (V[I>>3]&(1<<(I&7)))!=0
+
+/*
+** This routine runs an extensive test of the Bitvec code.
+**
+** The input is an array of integers that acts as a program
+** to test the Bitvec.  The integers are opcodes followed
+** by 0, 1, or 3 operands, depending on the opcode.  Another
+** opcode follows immediately after the last operand.
+**
+** There are 6 opcodes numbered from 0 through 5.  0 is the
+** "halt" opcode and causes the test to end.
+**
+**    0          Halt and return the number of errors
+**    1 N S X    Set N bits beginning with S and incrementing by X
+**    2 N S X    Clear N bits beginning with S and incrementing by X
+**    3 N        Set N randomly chosen bits
+**    4 N        Clear N randomly chosen bits
+**    5 N S X    Set N bits from S increment X in array only, not in bitvec
+**
+** The opcodes 1 through 4 perform set and clear operations are performed
+** on both a Bitvec object and on a linear array of bits obtained from malloc.
+** Opcode 5 works on the linear array only, not on the Bitvec.
+** Opcode 5 is used to deliberately induce a fault in order to
+** confirm that error detection works.
+**
+** At the conclusion of the test the linear array is compared
+** against the Bitvec object.  If there are any differences,
+** an error is returned.  If they are the same, zero is returned.
+**
+** If a memory allocation error occurs, return -1.
+*/
+SQLITE_PRIVATE int sqlite3BitvecBuiltinTest(int sz, int *aOp){
+  Bitvec *pBitvec = 0;
+  unsigned char *pV = 0;
+  int rc = -1;
+  int i, nx, pc, op;
+  void *pTmpSpace;
+
+  /* Allocate the Bitvec to be tested and a linear array of
+  ** bits to act as the reference */
+  pBitvec = sqlite3BitvecCreate( sz );
+  pV = sqlite3MallocZero( (sz+7)/8 + 1 );
+  pTmpSpace = sqlite3_malloc64(BITVEC_SZ);
+  if( pBitvec==0 || pV==0 || pTmpSpace==0  ) goto bitvec_end;
+
+  /* NULL pBitvec tests */
+  sqlite3BitvecSet(0, 1);
+  sqlite3BitvecClear(0, 1, pTmpSpace);
+
+  /* Run the program */
+  pc = 0;
+  while( (op = aOp[pc])!=0 ){
+    switch( op ){
+      case 1:
+      case 2:
+      case 5: {
+        nx = 4;
+        i = aOp[pc+2] - 1;
+        aOp[pc+2] += aOp[pc+3];
+        break;
+      }
+      case 3:
+      case 4: 
+      default: {
+        nx = 2;
+        sqlite3_randomness(sizeof(i), &i);
+        break;
+      }
+    }
+    if( (--aOp[pc+1]) > 0 ) nx = 0;
+    pc += nx;
+    i = (i & 0x7fffffff)%sz;
+    if( (op & 1)!=0 ){
+      SETBIT(pV, (i+1));
+      if( op!=5 ){
+        if( sqlite3BitvecSet(pBitvec, i+1) ) goto bitvec_end;
+      }
+    }else{
+      CLEARBIT(pV, (i+1));
+      sqlite3BitvecClear(pBitvec, i+1, pTmpSpace);
+    }
+  }
+
+  /* Test to make sure the linear array exactly matches the
+  ** Bitvec object.  Start with the assumption that they do
+  ** match (rc==0).  Change rc to non-zero if a discrepancy
+  ** is found.
+  */
+  rc = sqlite3BitvecTest(0,0) + sqlite3BitvecTest(pBitvec, sz+1)
+          + sqlite3BitvecTest(pBitvec, 0)
+          + (sqlite3BitvecSize(pBitvec) - sz);
+  for(i=1; i<=sz; i++){
+    if(  (TESTBIT(pV,i))!=sqlite3BitvecTest(pBitvec,i) ){
+      rc = i;
+      break;
+    }
+  }
+
+  /* Free allocated structure */
+bitvec_end:
+  sqlite3_free(pTmpSpace);
+  sqlite3_free(pV);
+  sqlite3BitvecDestroy(pBitvec);
+  return rc;
+}
+#endif /* SQLITE_OMIT_BUILTIN_TEST */
+
+/************** End of bitvec.c **********************************************/
+/************** Begin file pcache.c ******************************************/
+/*
+** 2008 August 05
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file implements that page cache.
+*/
+/* #include "sqliteInt.h" */
+
+/*
+** A complete page cache is an instance of this structure.  Every
+** entry in the cache holds a single page of the database file.  The
+** btree layer only operates on the cached copy of the database pages.
+**
+** A page cache entry is "clean" if it exactly matches what is currently
+** on disk.  A page is "dirty" if it has been modified and needs to be
+** persisted to disk.
+**
+** pDirty, pDirtyTail, pSynced:
+**   All dirty pages are linked into the doubly linked list using
+**   PgHdr.pDirtyNext and pDirtyPrev. The list is maintained in LRU order
+**   such that p was added to the list more recently than p->pDirtyNext.
+**   PCache.pDirty points to the first (newest) element in the list and
+**   pDirtyTail to the last (oldest).
+**
+**   The PCache.pSynced variable is used to optimize searching for a dirty
+**   page to eject from the cache mid-transaction. It is better to eject
+**   a page that does not require a journal sync than one that does. 
+**   Therefore, pSynced is maintained to that it *almost* always points
+**   to either the oldest page in the pDirty/pDirtyTail list that has a
+**   clear PGHDR_NEED_SYNC flag or to a page that is older than this one
+**   (so that the right page to eject can be found by following pDirtyPrev
+**   pointers).
+*/
+struct PCache {
+  PgHdr *pDirty, *pDirtyTail;         /* List of dirty pages in LRU order */
+  PgHdr *pSynced;                     /* Last synced page in dirty page list */
+  int nRefSum;                        /* Sum of ref counts over all pages */
+  int szCache;                        /* Configured cache size */
+  int szSpill;                        /* Size before spilling occurs */
+  int szPage;                         /* Size of every page in this cache */
+  int szExtra;                        /* Size of extra space for each page */
+  u8 bPurgeable;                      /* True if pages are on backing store */
+  u8 eCreate;                         /* eCreate value for for xFetch() */
+  int (*xStress)(void*,PgHdr*);       /* Call to try make a page clean */
+  void *pStress;                      /* Argument to xStress */
+  sqlite3_pcache *pCache;             /* Pluggable cache module */
+};
+
+/********************************** Test and Debug Logic **********************/
+/*
+** Debug tracing macros.  Enable by by changing the "0" to "1" and
+** recompiling.
+**
+** When sqlite3PcacheTrace is 1, single line trace messages are issued.
+** When sqlite3PcacheTrace is 2, a dump of the pcache showing all cache entries
+** is displayed for many operations, resulting in a lot of output.
+*/
+#if defined(SQLITE_DEBUG) && 0
+  int sqlite3PcacheTrace = 2;       /* 0: off  1: simple  2: cache dumps */
+  int sqlite3PcacheMxDump = 9999;   /* Max cache entries for pcacheDump() */
+# define pcacheTrace(X) if(sqlite3PcacheTrace){sqlite3DebugPrintf X;}
+  void pcacheDump(PCache *pCache){
+    int N;
+    int i, j;
+    sqlite3_pcache_page *pLower;
+    PgHdr *pPg;
+    unsigned char *a;
+  
+    if( sqlite3PcacheTrace<2 ) return;
+    if( pCache->pCache==0 ) return;
+    N = sqlite3PcachePagecount(pCache);
+    if( N>sqlite3PcacheMxDump ) N = sqlite3PcacheMxDump;
+    for(i=1; i<=N; i++){
+       pLower = sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache, i, 0);
+       if( pLower==0 ) continue;
+       pPg = (PgHdr*)pLower->pExtra;
+       printf("%3d: nRef %2d flgs %02x data ", i, pPg->nRef, pPg->flags);
+       a = (unsigned char *)pLower->pBuf;
+       for(j=0; j<12; j++) printf("%02x", a[j]);
+       printf("\n");
+       if( pPg->pPage==0 ){
+         sqlite3GlobalConfig.pcache2.xUnpin(pCache->pCache, pLower, 0);
+       }
+    }
+  }
+  #else
+# define pcacheTrace(X)
+# define pcacheDump(X)
+#endif
+
+/*
+** Check invariants on a PgHdr entry.  Return true if everything is OK.
+** Return false if any invariant is violated.
+**
+** This routine is for use inside of assert() statements only.  For
+** example:
+**
+**          assert( sqlite3PcachePageSanity(pPg) );
+*/
+#if SQLITE_DEBUG
+SQLITE_PRIVATE int sqlite3PcachePageSanity(PgHdr *pPg){
+  PCache *pCache;
+  assert( pPg!=0 );
+  assert( pPg->pgno>0 );    /* Page number is 1 or more */
+  pCache = pPg->pCache;
+  assert( pCache!=0 );      /* Every page has an associated PCache */
+  if( pPg->flags & PGHDR_CLEAN ){
+    assert( (pPg->flags & PGHDR_DIRTY)==0 );/* Cannot be both CLEAN and DIRTY */
+    assert( pCache->pDirty!=pPg );          /* CLEAN pages not on dirty list */
+    assert( pCache->pDirtyTail!=pPg );
+  }
+  /* WRITEABLE pages must also be DIRTY */
+  if( pPg->flags & PGHDR_WRITEABLE ){
+    assert( pPg->flags & PGHDR_DIRTY );     /* WRITEABLE implies DIRTY */
+  }
+  /* NEED_SYNC can be set independently of WRITEABLE.  This can happen,
+  ** for example, when using the sqlite3PagerDontWrite() optimization:
+  **    (1)  Page X is journalled, and gets WRITEABLE and NEED_SEEK.
+  **    (2)  Page X moved to freelist, WRITEABLE is cleared
+  **    (3)  Page X reused, WRITEABLE is set again
+  ** If NEED_SYNC had been cleared in step 2, then it would not be reset
+  ** in step 3, and page might be written into the database without first
+  ** syncing the rollback journal, which might cause corruption on a power
+  ** loss.
+  **
+  ** Another example is when the database page size is smaller than the
+  ** disk sector size.  When any page of a sector is journalled, all pages
+  ** in that sector are marked NEED_SYNC even if they are still CLEAN, just
+  ** in case they are later modified, since all pages in the same sector
+  ** must be journalled and synced before any of those pages can be safely
+  ** written.
+  */
+  return 1;
+}
+#endif /* SQLITE_DEBUG */
+
+
+/********************************** Linked List Management ********************/
+
+/* Allowed values for second argument to pcacheManageDirtyList() */
+#define PCACHE_DIRTYLIST_REMOVE   1    /* Remove pPage from dirty list */
+#define PCACHE_DIRTYLIST_ADD      2    /* Add pPage to the dirty list */
+#define PCACHE_DIRTYLIST_FRONT    3    /* Move pPage to the front of the list */
+
+/*
+** Manage pPage's participation on the dirty list.  Bits of the addRemove
+** argument determines what operation to do.  The 0x01 bit means first
+** remove pPage from the dirty list.  The 0x02 means add pPage back to
+** the dirty list.  Doing both moves pPage to the front of the dirty list.
+*/
+static void pcacheManageDirtyList(PgHdr *pPage, u8 addRemove){
+  PCache *p = pPage->pCache;
+
+  pcacheTrace(("%p.DIRTYLIST.%s %d\n", p,
+                addRemove==1 ? "REMOVE" : addRemove==2 ? "ADD" : "FRONT",
+                pPage->pgno));
+  if( addRemove & PCACHE_DIRTYLIST_REMOVE ){
+    assert( pPage->pDirtyNext || pPage==p->pDirtyTail );
+    assert( pPage->pDirtyPrev || pPage==p->pDirty );
+  
+    /* Update the PCache1.pSynced variable if necessary. */
+    if( p->pSynced==pPage ){
+      p->pSynced = pPage->pDirtyPrev;
+    }
+  
+    if( pPage->pDirtyNext ){
+      pPage->pDirtyNext->pDirtyPrev = pPage->pDirtyPrev;
+    }else{
+      assert( pPage==p->pDirtyTail );
+      p->pDirtyTail = pPage->pDirtyPrev;
+    }
+    if( pPage->pDirtyPrev ){
+      pPage->pDirtyPrev->pDirtyNext = pPage->pDirtyNext;
+    }else{
+      /* If there are now no dirty pages in the cache, set eCreate to 2. 
+      ** This is an optimization that allows sqlite3PcacheFetch() to skip
+      ** searching for a dirty page to eject from the cache when it might
+      ** otherwise have to.  */
+      assert( pPage==p->pDirty );
+      p->pDirty = pPage->pDirtyNext;
+      assert( p->bPurgeable || p->eCreate==2 );
+      if( p->pDirty==0 ){         /*OPTIMIZATION-IF-TRUE*/
+        assert( p->bPurgeable==0 || p->eCreate==1 );
+        p->eCreate = 2;
+      }
+    }
+    pPage->pDirtyNext = 0;
+    pPage->pDirtyPrev = 0;
+  }
+  if( addRemove & PCACHE_DIRTYLIST_ADD ){
+    assert( pPage->pDirtyNext==0 && pPage->pDirtyPrev==0 && p->pDirty!=pPage );
+  
+    pPage->pDirtyNext = p->pDirty;
+    if( pPage->pDirtyNext ){
+      assert( pPage->pDirtyNext->pDirtyPrev==0 );
+      pPage->pDirtyNext->pDirtyPrev = pPage;
+    }else{
+      p->pDirtyTail = pPage;
+      if( p->bPurgeable ){
+        assert( p->eCreate==2 );
+        p->eCreate = 1;
+      }
+    }
+    p->pDirty = pPage;
+
+    /* If pSynced is NULL and this page has a clear NEED_SYNC flag, set
+    ** pSynced to point to it. Checking the NEED_SYNC flag is an 
+    ** optimization, as if pSynced points to a page with the NEED_SYNC
+    ** flag set sqlite3PcacheFetchStress() searches through all newer 
+    ** entries of the dirty-list for a page with NEED_SYNC clear anyway.  */
+    if( !p->pSynced 
+     && 0==(pPage->flags&PGHDR_NEED_SYNC)   /*OPTIMIZATION-IF-FALSE*/
+    ){
+      p->pSynced = pPage;
+    }
+  }
+  pcacheDump(p);
+}
+
+/*
+** Wrapper around the pluggable caches xUnpin method. If the cache is
+** being used for an in-memory database, this function is a no-op.
+*/
+static void pcacheUnpin(PgHdr *p){
+  if( p->pCache->bPurgeable ){
+    pcacheTrace(("%p.UNPIN %d\n", p->pCache, p->pgno));
+    sqlite3GlobalConfig.pcache2.xUnpin(p->pCache->pCache, p->pPage, 0);
+    pcacheDump(p->pCache);
+  }
+}
+
+/*
+** Compute the number of pages of cache requested.   p->szCache is the
+** cache size requested by the "PRAGMA cache_size" statement.
+*/
+static int numberOfCachePages(PCache *p){
+  if( p->szCache>=0 ){
+    /* IMPLEMENTATION-OF: R-42059-47211 If the argument N is positive then the
+    ** suggested cache size is set to N. */
+    return p->szCache;
+  }else{
+    /* IMPLEMENTATION-OF: R-61436-13639 If the argument N is negative, then
+    ** the number of cache pages is adjusted to use approximately abs(N*1024)
+    ** bytes of memory. */
+    return (int)((-1024*(i64)p->szCache)/(p->szPage+p->szExtra));
+  }
+}
+
+/*************************************************** General Interfaces ******
+**
+** Initialize and shutdown the page cache subsystem. Neither of these 
+** functions are threadsafe.
+*/
+SQLITE_PRIVATE int sqlite3PcacheInitialize(void){
+  if( sqlite3GlobalConfig.pcache2.xInit==0 ){
+    /* IMPLEMENTATION-OF: R-26801-64137 If the xInit() method is NULL, then the
+    ** built-in default page cache is used instead of the application defined
+    ** page cache. */
+    sqlite3PCacheSetDefault();
+  }
+  return sqlite3GlobalConfig.pcache2.xInit(sqlite3GlobalConfig.pcache2.pArg);
+}
+SQLITE_PRIVATE void sqlite3PcacheShutdown(void){
+  if( sqlite3GlobalConfig.pcache2.xShutdown ){
+    /* IMPLEMENTATION-OF: R-26000-56589 The xShutdown() method may be NULL. */
+    sqlite3GlobalConfig.pcache2.xShutdown(sqlite3GlobalConfig.pcache2.pArg);
+  }
+}
+
+/*
+** Return the size in bytes of a PCache object.
+*/
+SQLITE_PRIVATE int sqlite3PcacheSize(void){ return sizeof(PCache); }
+
+/*
+** Create a new PCache object. Storage space to hold the object
+** has already been allocated and is passed in as the p pointer. 
+** The caller discovers how much space needs to be allocated by 
+** calling sqlite3PcacheSize().
+*/
+SQLITE_PRIVATE int sqlite3PcacheOpen(
+  int szPage,                  /* Size of every page */
+  int szExtra,                 /* Extra space associated with each page */
+  int bPurgeable,              /* True if pages are on backing store */
+  int (*xStress)(void*,PgHdr*),/* Call to try to make pages clean */
+  void *pStress,               /* Argument to xStress */
+  PCache *p                    /* Preallocated space for the PCache */
+){
+  memset(p, 0, sizeof(PCache));
+  p->szPage = 1;
+  p->szExtra = szExtra;
+  p->bPurgeable = bPurgeable;
+  p->eCreate = 2;
+  p->xStress = xStress;
+  p->pStress = pStress;
+  p->szCache = 100;
+  p->szSpill = 1;
+  pcacheTrace(("%p.OPEN szPage %d bPurgeable %d\n",p,szPage,bPurgeable));
+  return sqlite3PcacheSetPageSize(p, szPage);
+}
+
+/*
+** Change the page size for PCache object. The caller must ensure that there
+** are no outstanding page references when this function is called.
+*/
+SQLITE_PRIVATE int sqlite3PcacheSetPageSize(PCache *pCache, int szPage){
+  assert( pCache->nRefSum==0 && pCache->pDirty==0 );
+  if( pCache->szPage ){
+    sqlite3_pcache *pNew;
+    pNew = sqlite3GlobalConfig.pcache2.xCreate(
+                szPage, pCache->szExtra + ROUND8(sizeof(PgHdr)),
+                pCache->bPurgeable
+    );
+    if( pNew==0 ) return SQLITE_NOMEM_BKPT;
+    sqlite3GlobalConfig.pcache2.xCachesize(pNew, numberOfCachePages(pCache));
+    if( pCache->pCache ){
+      sqlite3GlobalConfig.pcache2.xDestroy(pCache->pCache);
+    }
+    pCache->pCache = pNew;
+    pCache->szPage = szPage;
+    pcacheTrace(("%p.PAGESIZE %d\n",pCache,szPage));
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Try to obtain a page from the cache.
+**
+** This routine returns a pointer to an sqlite3_pcache_page object if
+** such an object is already in cache, or if a new one is created.
+** This routine returns a NULL pointer if the object was not in cache
+** and could not be created.
+**
+** The createFlags should be 0 to check for existing pages and should
+** be 3 (not 1, but 3) to try to create a new page.
+**
+** If the createFlag is 0, then NULL is always returned if the page
+** is not already in the cache.  If createFlag is 1, then a new page
+** is created only if that can be done without spilling dirty pages
+** and without exceeding the cache size limit.
+**
+** The caller needs to invoke sqlite3PcacheFetchFinish() to properly
+** initialize the sqlite3_pcache_page object and convert it into a
+** PgHdr object.  The sqlite3PcacheFetch() and sqlite3PcacheFetchFinish()
+** routines are split this way for performance reasons. When separated
+** they can both (usually) operate without having to push values to
+** the stack on entry and pop them back off on exit, which saves a
+** lot of pushing and popping.
+*/
+SQLITE_PRIVATE sqlite3_pcache_page *sqlite3PcacheFetch(
+  PCache *pCache,       /* Obtain the page from this cache */
+  Pgno pgno,            /* Page number to obtain */
+  int createFlag        /* If true, create page if it does not exist already */
+){
+  int eCreate;
+  sqlite3_pcache_page *pRes;
+
+  assert( pCache!=0 );
+  assert( pCache->pCache!=0 );
+  assert( createFlag==3 || createFlag==0 );
+  assert( pgno>0 );
+  assert( pCache->eCreate==((pCache->bPurgeable && pCache->pDirty) ? 1 : 2) );
+
+  /* eCreate defines what to do if the page does not exist.
+  **    0     Do not allocate a new page.  (createFlag==0)
+  **    1     Allocate a new page if doing so is inexpensive.
+  **          (createFlag==1 AND bPurgeable AND pDirty)
+  **    2     Allocate a new page even it doing so is difficult.
+  **          (createFlag==1 AND !(bPurgeable AND pDirty)
+  */
+  eCreate = createFlag & pCache->eCreate;
+  assert( eCreate==0 || eCreate==1 || eCreate==2 );
+  assert( createFlag==0 || pCache->eCreate==eCreate );
+  assert( createFlag==0 || eCreate==1+(!pCache->bPurgeable||!pCache->pDirty) );
+  pRes = sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache, pgno, eCreate);
+  pcacheTrace(("%p.FETCH %d%s (result: %p)\n",pCache,pgno,
+               createFlag?" create":"",pRes));
+  return pRes;
+}
+
+/*
+** If the sqlite3PcacheFetch() routine is unable to allocate a new
+** page because no clean pages are available for reuse and the cache
+** size limit has been reached, then this routine can be invoked to 
+** try harder to allocate a page.  This routine might invoke the stress
+** callback to spill dirty pages to the journal.  It will then try to
+** allocate the new page and will only fail to allocate a new page on
+** an OOM error.
+**
+** This routine should be invoked only after sqlite3PcacheFetch() fails.
+*/
+SQLITE_PRIVATE int sqlite3PcacheFetchStress(
+  PCache *pCache,                 /* Obtain the page from this cache */
+  Pgno pgno,                      /* Page number to obtain */
+  sqlite3_pcache_page **ppPage    /* Write result here */
+){
+  PgHdr *pPg;
+  if( pCache->eCreate==2 ) return 0;
+
+  if( sqlite3PcachePagecount(pCache)>pCache->szSpill ){
+    /* Find a dirty page to write-out and recycle. First try to find a 
+    ** page that does not require a journal-sync (one with PGHDR_NEED_SYNC
+    ** cleared), but if that is not possible settle for any other 
+    ** unreferenced dirty page.
+    **
+    ** If the LRU page in the dirty list that has a clear PGHDR_NEED_SYNC
+    ** flag is currently referenced, then the following may leave pSynced
+    ** set incorrectly (pointing to other than the LRU page with NEED_SYNC
+    ** cleared). This is Ok, as pSynced is just an optimization.  */
+    for(pPg=pCache->pSynced; 
+        pPg && (pPg->nRef || (pPg->flags&PGHDR_NEED_SYNC)); 
+        pPg=pPg->pDirtyPrev
+    );
+    pCache->pSynced = pPg;
+    if( !pPg ){
+      for(pPg=pCache->pDirtyTail; pPg && pPg->nRef; pPg=pPg->pDirtyPrev);
+    }
+    if( pPg ){
+      int rc;
+#ifdef SQLITE_LOG_CACHE_SPILL
+      sqlite3_log(SQLITE_FULL, 
+                  "spill page %d making room for %d - cache used: %d/%d",
+                  pPg->pgno, pgno,
+                  sqlite3GlobalConfig.pcache.xPagecount(pCache->pCache),
+                numberOfCachePages(pCache));
+#endif
+      pcacheTrace(("%p.SPILL %d\n",pCache,pPg->pgno));
+      rc = pCache->xStress(pCache->pStress, pPg);
+      pcacheDump(pCache);
+      if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){
+        return rc;
+      }
+    }
+  }
+  *ppPage = sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache, pgno, 2);
+  return *ppPage==0 ? SQLITE_NOMEM_BKPT : SQLITE_OK;
+}
+
+/*
+** This is a helper routine for sqlite3PcacheFetchFinish()
+**
+** In the uncommon case where the page being fetched has not been
+** initialized, this routine is invoked to do the initialization.
+** This routine is broken out into a separate function since it
+** requires extra stack manipulation that can be avoided in the common
+** case.
+*/
+static SQLITE_NOINLINE PgHdr *pcacheFetchFinishWithInit(
+  PCache *pCache,             /* Obtain the page from this cache */
+  Pgno pgno,                  /* Page number obtained */
+  sqlite3_pcache_page *pPage  /* Page obtained by prior PcacheFetch() call */
+){
+  PgHdr *pPgHdr;
+  assert( pPage!=0 );
+  pPgHdr = (PgHdr*)pPage->pExtra;
+  assert( pPgHdr->pPage==0 );
+  memset(&pPgHdr->pDirty, 0, sizeof(PgHdr) - offsetof(PgHdr,pDirty));
+  pPgHdr->pPage = pPage;
+  pPgHdr->pData = pPage->pBuf;
+  pPgHdr->pExtra = (void *)&pPgHdr[1];
+  memset(pPgHdr->pExtra, 0, pCache->szExtra);
+  pPgHdr->pCache = pCache;
+  pPgHdr->pgno = pgno;
+  pPgHdr->flags = PGHDR_CLEAN;
+  return sqlite3PcacheFetchFinish(pCache,pgno,pPage);
+}
+
+/*
+** This routine converts the sqlite3_pcache_page object returned by
+** sqlite3PcacheFetch() into an initialized PgHdr object.  This routine
+** must be called after sqlite3PcacheFetch() in order to get a usable
+** result.
+*/
+SQLITE_PRIVATE PgHdr *sqlite3PcacheFetchFinish(
+  PCache *pCache,             /* Obtain the page from this cache */
+  Pgno pgno,                  /* Page number obtained */
+  sqlite3_pcache_page *pPage  /* Page obtained by prior PcacheFetch() call */
+){
+  PgHdr *pPgHdr;
+
+  assert( pPage!=0 );
+  pPgHdr = (PgHdr *)pPage->pExtra;
+
+  if( !pPgHdr->pPage ){
+    return pcacheFetchFinishWithInit(pCache, pgno, pPage);
+  }
+  pCache->nRefSum++;
+  pPgHdr->nRef++;
+  assert( sqlite3PcachePageSanity(pPgHdr) );
+  return pPgHdr;
+}
+
+/*
+** Decrement the reference count on a page. If the page is clean and the
+** reference count drops to 0, then it is made eligible for recycling.
+*/
+SQLITE_PRIVATE void SQLITE_NOINLINE sqlite3PcacheRelease(PgHdr *p){
+  assert( p->nRef>0 );
+  p->pCache->nRefSum--;
+  if( (--p->nRef)==0 ){
+    if( p->flags&PGHDR_CLEAN ){
+      pcacheUnpin(p);
+    }else if( p->pDirtyPrev!=0 ){ /*OPTIMIZATION-IF-FALSE*/
+      /* Move the page to the head of the dirty list. If p->pDirtyPrev==0,
+      ** then page p is already at the head of the dirty list and the
+      ** following call would be a no-op. Hence the OPTIMIZATION-IF-FALSE
+      ** tag above.  */
+      pcacheManageDirtyList(p, PCACHE_DIRTYLIST_FRONT);
+    }
+  }
+}
+
+/*
+** Increase the reference count of a supplied page by 1.
+*/
+SQLITE_PRIVATE void sqlite3PcacheRef(PgHdr *p){
+  assert(p->nRef>0);
+  assert( sqlite3PcachePageSanity(p) );
+  p->nRef++;
+  p->pCache->nRefSum++;
+}
+
+/*
+** Drop a page from the cache. There must be exactly one reference to the
+** page. This function deletes that reference, so after it returns the
+** page pointed to by p is invalid.
+*/
+SQLITE_PRIVATE void sqlite3PcacheDrop(PgHdr *p){
+  assert( p->nRef==1 );
+  assert( sqlite3PcachePageSanity(p) );
+  if( p->flags&PGHDR_DIRTY ){
+    pcacheManageDirtyList(p, PCACHE_DIRTYLIST_REMOVE);
+  }
+  p->pCache->nRefSum--;
+  sqlite3GlobalConfig.pcache2.xUnpin(p->pCache->pCache, p->pPage, 1);
+}
+
+/*
+** Make sure the page is marked as dirty. If it isn't dirty already,
+** make it so.
+*/
+SQLITE_PRIVATE void sqlite3PcacheMakeDirty(PgHdr *p){
+  assert( p->nRef>0 );
+  assert( sqlite3PcachePageSanity(p) );
+  if( p->flags & (PGHDR_CLEAN|PGHDR_DONT_WRITE) ){    /*OPTIMIZATION-IF-FALSE*/
+    p->flags &= ~PGHDR_DONT_WRITE;
+    if( p->flags & PGHDR_CLEAN ){
+      p->flags ^= (PGHDR_DIRTY|PGHDR_CLEAN);
+      pcacheTrace(("%p.DIRTY %d\n",p->pCache,p->pgno));
+      assert( (p->flags & (PGHDR_DIRTY|PGHDR_CLEAN))==PGHDR_DIRTY );
+      pcacheManageDirtyList(p, PCACHE_DIRTYLIST_ADD);
+    }
+    assert( sqlite3PcachePageSanity(p) );
+  }
+}
+
+/*
+** Make sure the page is marked as clean. If it isn't clean already,
+** make it so.
+*/
+SQLITE_PRIVATE void sqlite3PcacheMakeClean(PgHdr *p){
+  assert( sqlite3PcachePageSanity(p) );
+  if( ALWAYS((p->flags & PGHDR_DIRTY)!=0) ){
+    assert( (p->flags & PGHDR_CLEAN)==0 );
+    pcacheManageDirtyList(p, PCACHE_DIRTYLIST_REMOVE);
+    p->flags &= ~(PGHDR_DIRTY|PGHDR_NEED_SYNC|PGHDR_WRITEABLE);
+    p->flags |= PGHDR_CLEAN;
+    pcacheTrace(("%p.CLEAN %d\n",p->pCache,p->pgno));
+    assert( sqlite3PcachePageSanity(p) );
+    if( p->nRef==0 ){
+      pcacheUnpin(p);
+    }
+  }
+}
+
+/*
+** Make every page in the cache clean.
+*/
+SQLITE_PRIVATE void sqlite3PcacheCleanAll(PCache *pCache){
+  PgHdr *p;
+  pcacheTrace(("%p.CLEAN-ALL\n",pCache));
+  while( (p = pCache->pDirty)!=0 ){
+    sqlite3PcacheMakeClean(p);
+  }
+}
+
+/*
+** Clear the PGHDR_NEED_SYNC and PGHDR_WRITEABLE flag from all dirty pages.
+*/
+SQLITE_PRIVATE void sqlite3PcacheClearWritable(PCache *pCache){
+  PgHdr *p;
+  pcacheTrace(("%p.CLEAR-WRITEABLE\n",pCache));
+  for(p=pCache->pDirty; p; p=p->pDirtyNext){
+    p->flags &= ~(PGHDR_NEED_SYNC|PGHDR_WRITEABLE);
+  }
+  pCache->pSynced = pCache->pDirtyTail;
+}
+
+/*
+** Clear the PGHDR_NEED_SYNC flag from all dirty pages.
+*/
+SQLITE_PRIVATE void sqlite3PcacheClearSyncFlags(PCache *pCache){
+  PgHdr *p;
+  for(p=pCache->pDirty; p; p=p->pDirtyNext){
+    p->flags &= ~PGHDR_NEED_SYNC;
+  }
+  pCache->pSynced = pCache->pDirtyTail;
+}
+
+/*
+** Change the page number of page p to newPgno. 
+*/
+SQLITE_PRIVATE void sqlite3PcacheMove(PgHdr *p, Pgno newPgno){
+  PCache *pCache = p->pCache;
+  assert( p->nRef>0 );
+  assert( newPgno>0 );
+  assert( sqlite3PcachePageSanity(p) );
+  pcacheTrace(("%p.MOVE %d -> %d\n",pCache,p->pgno,newPgno));
+  sqlite3GlobalConfig.pcache2.xRekey(pCache->pCache, p->pPage, p->pgno,newPgno);
+  p->pgno = newPgno;
+  if( (p->flags&PGHDR_DIRTY) && (p->flags&PGHDR_NEED_SYNC) ){
+    pcacheManageDirtyList(p, PCACHE_DIRTYLIST_FRONT);
+  }
+}
+
+/*
+** Drop every cache entry whose page number is greater than "pgno". The
+** caller must ensure that there are no outstanding references to any pages
+** other than page 1 with a page number greater than pgno.
+**
+** If there is a reference to page 1 and the pgno parameter passed to this
+** function is 0, then the data area associated with page 1 is zeroed, but
+** the page object is not dropped.
+*/
+SQLITE_PRIVATE void sqlite3PcacheTruncate(PCache *pCache, Pgno pgno){
+  if( pCache->pCache ){
+    PgHdr *p;
+    PgHdr *pNext;
+    pcacheTrace(("%p.TRUNCATE %d\n",pCache,pgno));
+    for(p=pCache->pDirty; p; p=pNext){
+      pNext = p->pDirtyNext;
+      /* This routine never gets call with a positive pgno except right
+      ** after sqlite3PcacheCleanAll().  So if there are dirty pages,
+      ** it must be that pgno==0.
+      */
+      assert( p->pgno>0 );
+      if( p->pgno>pgno ){
+        assert( p->flags&PGHDR_DIRTY );
+        sqlite3PcacheMakeClean(p);
+      }
+    }
+    if( pgno==0 && pCache->nRefSum ){
+      sqlite3_pcache_page *pPage1;
+      pPage1 = sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache,1,0);
+      if( ALWAYS(pPage1) ){  /* Page 1 is always available in cache, because
+                             ** pCache->nRefSum>0 */
+        memset(pPage1->pBuf, 0, pCache->szPage);
+        pgno = 1;
+      }
+    }
+    sqlite3GlobalConfig.pcache2.xTruncate(pCache->pCache, pgno+1);
+  }
+}
+
+/*
+** Close a cache.
+*/
+SQLITE_PRIVATE void sqlite3PcacheClose(PCache *pCache){
+  assert( pCache->pCache!=0 );
+  pcacheTrace(("%p.CLOSE\n",pCache));
+  sqlite3GlobalConfig.pcache2.xDestroy(pCache->pCache);
+}
+
+/* 
+** Discard the contents of the cache.
+*/
+SQLITE_PRIVATE void sqlite3PcacheClear(PCache *pCache){
+  sqlite3PcacheTruncate(pCache, 0);
+}
+
+/*
+** Merge two lists of pages connected by pDirty and in pgno order.
+** Do not bother fixing the pDirtyPrev pointers.
+*/
+static PgHdr *pcacheMergeDirtyList(PgHdr *pA, PgHdr *pB){
+  PgHdr result, *pTail;
+  pTail = &result;
+  assert( pA!=0 && pB!=0 );
+  for(;;){
+    if( pA->pgno<pB->pgno ){
+      pTail->pDirty = pA;
+      pTail = pA;
+      pA = pA->pDirty;
+      if( pA==0 ){
+        pTail->pDirty = pB;
+        break;
+      }
+    }else{
+      pTail->pDirty = pB;
+      pTail = pB;
+      pB = pB->pDirty;
+      if( pB==0 ){
+        pTail->pDirty = pA;
+        break;
+      }
+    }
+  }
+  return result.pDirty;
+}
+
+/*
+** Sort the list of pages in accending order by pgno.  Pages are
+** connected by pDirty pointers.  The pDirtyPrev pointers are
+** corrupted by this sort.
+**
+** Since there cannot be more than 2^31 distinct pages in a database,
+** there cannot be more than 31 buckets required by the merge sorter.
+** One extra bucket is added to catch overflow in case something
+** ever changes to make the previous sentence incorrect.
+*/
+#define N_SORT_BUCKET  32
+static PgHdr *pcacheSortDirtyList(PgHdr *pIn){
+  PgHdr *a[N_SORT_BUCKET], *p;
+  int i;
+  memset(a, 0, sizeof(a));
+  while( pIn ){
+    p = pIn;
+    pIn = p->pDirty;
+    p->pDirty = 0;
+    for(i=0; ALWAYS(i<N_SORT_BUCKET-1); i++){
+      if( a[i]==0 ){
+        a[i] = p;
+        break;
+      }else{
+        p = pcacheMergeDirtyList(a[i], p);
+        a[i] = 0;
+      }
+    }
+    if( NEVER(i==N_SORT_BUCKET-1) ){
+      /* To get here, there need to be 2^(N_SORT_BUCKET) elements in
+      ** the input list.  But that is impossible.
+      */
+      a[i] = pcacheMergeDirtyList(a[i], p);
+    }
+  }
+  p = a[0];
+  for(i=1; i<N_SORT_BUCKET; i++){
+    if( a[i]==0 ) continue;
+    p = p ? pcacheMergeDirtyList(p, a[i]) : a[i];
+  }
+  return p;
+}
+
+/*
+** Return a list of all dirty pages in the cache, sorted by page number.
+*/
+SQLITE_PRIVATE PgHdr *sqlite3PcacheDirtyList(PCache *pCache){
+  PgHdr *p;
+  for(p=pCache->pDirty; p; p=p->pDirtyNext){
+    p->pDirty = p->pDirtyNext;
+  }
+  return pcacheSortDirtyList(pCache->pDirty);
+}
+
+/* 
+** Return the total number of references to all pages held by the cache.
+**
+** This is not the total number of pages referenced, but the sum of the
+** reference count for all pages.
+*/
+SQLITE_PRIVATE int sqlite3PcacheRefCount(PCache *pCache){
+  return pCache->nRefSum;
+}
+
+/*
+** Return the number of references to the page supplied as an argument.
+*/
+SQLITE_PRIVATE int sqlite3PcachePageRefcount(PgHdr *p){
+  return p->nRef;
+}
+
+/* 
+** Return the total number of pages in the cache.
+*/
+SQLITE_PRIVATE int sqlite3PcachePagecount(PCache *pCache){
+  assert( pCache->pCache!=0 );
+  return sqlite3GlobalConfig.pcache2.xPagecount(pCache->pCache);
+}
+
+#ifdef SQLITE_TEST
+/*
+** Get the suggested cache-size value.
+*/
+SQLITE_PRIVATE int sqlite3PcacheGetCachesize(PCache *pCache){
+  return numberOfCachePages(pCache);
+}
+#endif
+
+/*
+** Set the suggested cache-size value.
+*/
+SQLITE_PRIVATE void sqlite3PcacheSetCachesize(PCache *pCache, int mxPage){
+  assert( pCache->pCache!=0 );
+  pCache->szCache = mxPage;
+  sqlite3GlobalConfig.pcache2.xCachesize(pCache->pCache,
+                                         numberOfCachePages(pCache));
+}
+
+/*
+** Set the suggested cache-spill value.  Make no changes if if the
+** argument is zero.  Return the effective cache-spill size, which will
+** be the larger of the szSpill and szCache.
+*/
+SQLITE_PRIVATE int sqlite3PcacheSetSpillsize(PCache *p, int mxPage){
+  int res;
+  assert( p->pCache!=0 );
+  if( mxPage ){
+    if( mxPage<0 ){
+      mxPage = (int)((-1024*(i64)mxPage)/(p->szPage+p->szExtra));
+    }
+    p->szSpill = mxPage;
+  }
+  res = numberOfCachePages(p);
+  if( res<p->szSpill ) res = p->szSpill; 
+  return res;
+}
+
+/*
+** Free up as much memory as possible from the page cache.
+*/
+SQLITE_PRIVATE void sqlite3PcacheShrink(PCache *pCache){
+  assert( pCache->pCache!=0 );
+  sqlite3GlobalConfig.pcache2.xShrink(pCache->pCache);
+}
+
+/*
+** Return the size of the header added by this middleware layer
+** in the page-cache hierarchy.
+*/
+SQLITE_PRIVATE int sqlite3HeaderSizePcache(void){ return ROUND8(sizeof(PgHdr)); }
+
+/*
+** Return the number of dirty pages currently in the cache, as a percentage
+** of the configured cache size.
+*/
+SQLITE_PRIVATE int sqlite3PCachePercentDirty(PCache *pCache){
+  PgHdr *pDirty;
+  int nDirty = 0;
+  int nCache = numberOfCachePages(pCache);
+  for(pDirty=pCache->pDirty; pDirty; pDirty=pDirty->pDirtyNext) nDirty++;
+  return nCache ? (int)(((i64)nDirty * 100) / nCache) : 0;
+}
+
+#if defined(SQLITE_CHECK_PAGES) || defined(SQLITE_DEBUG)
+/*
+** For all dirty pages currently in the cache, invoke the specified
+** callback. This is only used if the SQLITE_CHECK_PAGES macro is
+** defined.
+*/
+SQLITE_PRIVATE void sqlite3PcacheIterateDirty(PCache *pCache, void (*xIter)(PgHdr *)){
+  PgHdr *pDirty;
+  for(pDirty=pCache->pDirty; pDirty; pDirty=pDirty->pDirtyNext){
+    xIter(pDirty);
+  }
+}
+#endif
+
+/************** End of pcache.c **********************************************/
+/************** Begin file pcache1.c *****************************************/
+/*
+** 2008 November 05
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file implements the default page cache implementation (the
+** sqlite3_pcache interface). It also contains part of the implementation
+** of the SQLITE_CONFIG_PAGECACHE and sqlite3_release_memory() features.
+** If the default page cache implementation is overridden, then neither of
+** these two features are available.
+**
+** A Page cache line looks like this:
+**
+**  -------------------------------------------------------------
+**  |  database page content   |  PgHdr1  |  MemPage  |  PgHdr  |
+**  -------------------------------------------------------------
+**
+** The database page content is up front (so that buffer overreads tend to
+** flow harmlessly into the PgHdr1, MemPage, and PgHdr extensions).   MemPage
+** is the extension added by the btree.c module containing information such
+** as the database page number and how that database page is used.  PgHdr
+** is added by the pcache.c layer and contains information used to keep track
+** of which pages are "dirty".  PgHdr1 is an extension added by this
+** module (pcache1.c).  The PgHdr1 header is a subclass of sqlite3_pcache_page.
+** PgHdr1 contains information needed to look up a page by its page number.
+** The superclass sqlite3_pcache_page.pBuf points to the start of the
+** database page content and sqlite3_pcache_page.pExtra points to PgHdr.
+**
+** The size of the extension (MemPage+PgHdr+PgHdr1) can be determined at
+** runtime using sqlite3_config(SQLITE_CONFIG_PCACHE_HDRSZ, &size).  The
+** sizes of the extensions sum to 272 bytes on x64 for 3.8.10, but this
+** size can vary according to architecture, compile-time options, and
+** SQLite library version number.
+**
+** If SQLITE_PCACHE_SEPARATE_HEADER is defined, then the extension is obtained
+** using a separate memory allocation from the database page content.  This
+** seeks to overcome the "clownshoe" problem (also called "internal
+** fragmentation" in academic literature) of allocating a few bytes more
+** than a power of two with the memory allocator rounding up to the next
+** power of two, and leaving the rounded-up space unused.
+**
+** This module tracks pointers to PgHdr1 objects.  Only pcache.c communicates
+** with this module.  Information is passed back and forth as PgHdr1 pointers.
+**
+** The pcache.c and pager.c modules deal pointers to PgHdr objects.
+** The btree.c module deals with pointers to MemPage objects.
+**
+** SOURCE OF PAGE CACHE MEMORY:
+**
+** Memory for a page might come from any of three sources:
+**
+**    (1)  The general-purpose memory allocator - sqlite3Malloc()
+**    (2)  Global page-cache memory provided using sqlite3_config() with
+**         SQLITE_CONFIG_PAGECACHE.
+**    (3)  PCache-local bulk allocation.
+**
+** The third case is a chunk of heap memory (defaulting to 100 pages worth)
+** that is allocated when the page cache is created.  The size of the local
+** bulk allocation can be adjusted using 
+**
+**     sqlite3_config(SQLITE_CONFIG_PAGECACHE, (void*)0, 0, N).
+**
+** If N is positive, then N pages worth of memory are allocated using a single
+** sqlite3Malloc() call and that memory is used for the first N pages allocated.
+** Or if N is negative, then -1024*N bytes of memory are allocated and used
+** for as many pages as can be accomodated.
+**
+** Only one of (2) or (3) can be used.  Once the memory available to (2) or
+** (3) is exhausted, subsequent allocations fail over to the general-purpose
+** memory allocator (1).
+**
+** Earlier versions of SQLite used only methods (1) and (2).  But experiments
+** show that method (3) with N==100 provides about a 5% performance boost for
+** common workloads.
+*/
+/* #include "sqliteInt.h" */
+
+typedef struct PCache1 PCache1;
+typedef struct PgHdr1 PgHdr1;
+typedef struct PgFreeslot PgFreeslot;
+typedef struct PGroup PGroup;
+
+/*
+** Each cache entry is represented by an instance of the following 
+** structure. Unless SQLITE_PCACHE_SEPARATE_HEADER is defined, a buffer of
+** PgHdr1.pCache->szPage bytes is allocated directly before this structure 
+** in memory.
+*/
+struct PgHdr1 {
+  sqlite3_pcache_page page;      /* Base class. Must be first. pBuf & pExtra */
+  unsigned int iKey;             /* Key value (page number) */
+  u8 isPinned;                   /* Page in use, not on the LRU list */
+  u8 isBulkLocal;                /* This page from bulk local storage */
+  u8 isAnchor;                   /* This is the PGroup.lru element */
+  PgHdr1 *pNext;                 /* Next in hash table chain */
+  PCache1 *pCache;               /* Cache that currently owns this page */
+  PgHdr1 *pLruNext;              /* Next in LRU list of unpinned pages */
+  PgHdr1 *pLruPrev;              /* Previous in LRU list of unpinned pages */
+};
+
+/* Each page cache (or PCache) belongs to a PGroup.  A PGroup is a set 
+** of one or more PCaches that are able to recycle each other's unpinned
+** pages when they are under memory pressure.  A PGroup is an instance of
+** the following object.
+**
+** This page cache implementation works in one of two modes:
+**
+**   (1)  Every PCache is the sole member of its own PGroup.  There is
+**        one PGroup per PCache.
+**
+**   (2)  There is a single global PGroup that all PCaches are a member
+**        of.
+**
+** Mode 1 uses more memory (since PCache instances are not able to rob
+** unused pages from other PCaches) but it also operates without a mutex,
+** and is therefore often faster.  Mode 2 requires a mutex in order to be
+** threadsafe, but recycles pages more efficiently.
+**
+** For mode (1), PGroup.mutex is NULL.  For mode (2) there is only a single
+** PGroup which is the pcache1.grp global variable and its mutex is
+** SQLITE_MUTEX_STATIC_LRU.
+*/
+struct PGroup {
+  sqlite3_mutex *mutex;          /* MUTEX_STATIC_LRU or NULL */
+  unsigned int nMaxPage;         /* Sum of nMax for purgeable caches */
+  unsigned int nMinPage;         /* Sum of nMin for purgeable caches */
+  unsigned int mxPinned;         /* nMaxpage + 10 - nMinPage */
+  unsigned int nCurrentPage;     /* Number of purgeable pages allocated */
+  PgHdr1 lru;                    /* The beginning and end of the LRU list */
+};
+
+/* Each page cache is an instance of the following object.  Every
+** open database file (including each in-memory database and each
+** temporary or transient database) has a single page cache which
+** is an instance of this object.
+**
+** Pointers to structures of this type are cast and returned as 
+** opaque sqlite3_pcache* handles.
+*/
+struct PCache1 {
+  /* Cache configuration parameters. Page size (szPage) and the purgeable
+  ** flag (bPurgeable) are set when the cache is created. nMax may be 
+  ** modified at any time by a call to the pcache1Cachesize() method.
+  ** The PGroup mutex must be held when accessing nMax.
+  */
+  PGroup *pGroup;                     /* PGroup this cache belongs to */
+  int szPage;                         /* Size of database content section */
+  int szExtra;                        /* sizeof(MemPage)+sizeof(PgHdr) */
+  int szAlloc;                        /* Total size of one pcache line */
+  int bPurgeable;                     /* True if cache is purgeable */
+  unsigned int nMin;                  /* Minimum number of pages reserved */
+  unsigned int nMax;                  /* Configured "cache_size" value */
+  unsigned int n90pct;                /* nMax*9/10 */
+  unsigned int iMaxKey;               /* Largest key seen since xTruncate() */
+
+  /* Hash table of all pages. The following variables may only be accessed
+  ** when the accessor is holding the PGroup mutex.
+  */
+  unsigned int nRecyclable;           /* Number of pages in the LRU list */
+  unsigned int nPage;                 /* Total number of pages in apHash */
+  unsigned int nHash;                 /* Number of slots in apHash[] */
+  PgHdr1 **apHash;                    /* Hash table for fast lookup by key */
+  PgHdr1 *pFree;                      /* List of unused pcache-local pages */
+  void *pBulk;                        /* Bulk memory used by pcache-local */
+};
+
+/*
+** Free slots in the allocator used to divide up the global page cache
+** buffer provided using the SQLITE_CONFIG_PAGECACHE mechanism.
+*/
+struct PgFreeslot {
+  PgFreeslot *pNext;  /* Next free slot */
+};
+
+/*
+** Global data used by this cache.
+*/
+static SQLITE_WSD struct PCacheGlobal {
+  PGroup grp;                    /* The global PGroup for mode (2) */
+
+  /* Variables related to SQLITE_CONFIG_PAGECACHE settings.  The
+  ** szSlot, nSlot, pStart, pEnd, nReserve, and isInit values are all
+  ** fixed at sqlite3_initialize() time and do not require mutex protection.
+  ** The nFreeSlot and pFree values do require mutex protection.
+  */
+  int isInit;                    /* True if initialized */
+  int separateCache;             /* Use a new PGroup for each PCache */
+  int nInitPage;                 /* Initial bulk allocation size */   
+  int szSlot;                    /* Size of each free slot */
+  int nSlot;                     /* The number of pcache slots */
+  int nReserve;                  /* Try to keep nFreeSlot above this */
+  void *pStart, *pEnd;           /* Bounds of global page cache memory */
+  /* Above requires no mutex.  Use mutex below for variable that follow. */
+  sqlite3_mutex *mutex;          /* Mutex for accessing the following: */
+  PgFreeslot *pFree;             /* Free page blocks */
+  int nFreeSlot;                 /* Number of unused pcache slots */
+  /* The following value requires a mutex to change.  We skip the mutex on
+  ** reading because (1) most platforms read a 32-bit integer atomically and
+  ** (2) even if an incorrect value is read, no great harm is done since this
+  ** is really just an optimization. */
+  int bUnderPressure;            /* True if low on PAGECACHE memory */
+} pcache1_g;
+
+/*
+** All code in this file should access the global structure above via the
+** alias "pcache1". This ensures that the WSD emulation is used when
+** compiling for systems that do not support real WSD.
+*/
+#define pcache1 (GLOBAL(struct PCacheGlobal, pcache1_g))
+
+/*
+** Macros to enter and leave the PCache LRU mutex.
+*/
+#if !defined(SQLITE_ENABLE_MEMORY_MANAGEMENT) || SQLITE_THREADSAFE==0
+# define pcache1EnterMutex(X)  assert((X)->mutex==0)
+# define pcache1LeaveMutex(X)  assert((X)->mutex==0)
+# define PCACHE1_MIGHT_USE_GROUP_MUTEX 0
+#else
+# define pcache1EnterMutex(X) sqlite3_mutex_enter((X)->mutex)
+# define pcache1LeaveMutex(X) sqlite3_mutex_leave((X)->mutex)
+# define PCACHE1_MIGHT_USE_GROUP_MUTEX 1
+#endif
+
+/******************************************************************************/
+/******** Page Allocation/SQLITE_CONFIG_PCACHE Related Functions **************/
+
+
+/*
+** This function is called during initialization if a static buffer is 
+** supplied to use for the page-cache by passing the SQLITE_CONFIG_PAGECACHE
+** verb to sqlite3_config(). Parameter pBuf points to an allocation large
+** enough to contain 'n' buffers of 'sz' bytes each.
+**
+** This routine is called from sqlite3_initialize() and so it is guaranteed
+** to be serialized already.  There is no need for further mutexing.
+*/
+SQLITE_PRIVATE void sqlite3PCacheBufferSetup(void *pBuf, int sz, int n){
+  if( pcache1.isInit ){
+    PgFreeslot *p;
+    if( pBuf==0 ) sz = n = 0;
+    sz = ROUNDDOWN8(sz);
+    pcache1.szSlot = sz;
+    pcache1.nSlot = pcache1.nFreeSlot = n;
+    pcache1.nReserve = n>90 ? 10 : (n/10 + 1);
+    pcache1.pStart = pBuf;
+    pcache1.pFree = 0;
+    pcache1.bUnderPressure = 0;
+    while( n-- ){
+      p = (PgFreeslot*)pBuf;
+      p->pNext = pcache1.pFree;
+      pcache1.pFree = p;
+      pBuf = (void*)&((char*)pBuf)[sz];
+    }
+    pcache1.pEnd = pBuf;
+  }
+}
+
+/*
+** Try to initialize the pCache->pFree and pCache->pBulk fields.  Return
+** true if pCache->pFree ends up containing one or more free pages.
+*/
+static int pcache1InitBulk(PCache1 *pCache){
+  i64 szBulk;
+  char *zBulk;
+  if( pcache1.nInitPage==0 ) return 0;
+  /* Do not bother with a bulk allocation if the cache size very small */
+  if( pCache->nMax<3 ) return 0;
+  sqlite3BeginBenignMalloc();
+  if( pcache1.nInitPage>0 ){
+    szBulk = pCache->szAlloc * (i64)pcache1.nInitPage;
+  }else{
+    szBulk = -1024 * (i64)pcache1.nInitPage;
+  }
+  if( szBulk > pCache->szAlloc*(i64)pCache->nMax ){
+    szBulk = pCache->szAlloc*(i64)pCache->nMax;
+  }
+  zBulk = pCache->pBulk = sqlite3Malloc( szBulk );
+  sqlite3EndBenignMalloc();
+  if( zBulk ){
+    int nBulk = sqlite3MallocSize(zBulk)/pCache->szAlloc;
+    int i;
+    for(i=0; i<nBulk; i++){
+      PgHdr1 *pX = (PgHdr1*)&zBulk[pCache->szPage];
+      pX->page.pBuf = zBulk;
+      pX->page.pExtra = &pX[1];
+      pX->isBulkLocal = 1;
+      pX->isAnchor = 0;
+      pX->pNext = pCache->pFree;
+      pCache->pFree = pX;
+      zBulk += pCache->szAlloc;
+    }
+  }
+  return pCache->pFree!=0;
+}
+
+/*
+** Malloc function used within this file to allocate space from the buffer
+** configured using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no 
+** such buffer exists or there is no space left in it, this function falls 
+** back to sqlite3Malloc().
+**
+** Multiple threads can run this routine at the same time.  Global variables
+** in pcache1 need to be protected via mutex.
+*/
+static void *pcache1Alloc(int nByte){
+  void *p = 0;
+  assert( sqlite3_mutex_notheld(pcache1.grp.mutex) );
+  if( nByte<=pcache1.szSlot ){
+    sqlite3_mutex_enter(pcache1.mutex);
+    p = (PgHdr1 *)pcache1.pFree;
+    if( p ){
+      pcache1.pFree = pcache1.pFree->pNext;
+      pcache1.nFreeSlot--;
+      pcache1.bUnderPressure = pcache1.nFreeSlot<pcache1.nReserve;
+      assert( pcache1.nFreeSlot>=0 );
+      sqlite3StatusHighwater(SQLITE_STATUS_PAGECACHE_SIZE, nByte);
+      sqlite3StatusUp(SQLITE_STATUS_PAGECACHE_USED, 1);
+    }
+    sqlite3_mutex_leave(pcache1.mutex);
+  }
+  if( p==0 ){
+    /* Memory is not available in the SQLITE_CONFIG_PAGECACHE pool.  Get
+    ** it from sqlite3Malloc instead.
+    */
+    p = sqlite3Malloc(nByte);
+#ifndef SQLITE_DISABLE_PAGECACHE_OVERFLOW_STATS
+    if( p ){
+      int sz = sqlite3MallocSize(p);
+      sqlite3_mutex_enter(pcache1.mutex);
+      sqlite3StatusHighwater(SQLITE_STATUS_PAGECACHE_SIZE, nByte);
+      sqlite3StatusUp(SQLITE_STATUS_PAGECACHE_OVERFLOW, sz);
+      sqlite3_mutex_leave(pcache1.mutex);
+    }
+#endif
+    sqlite3MemdebugSetType(p, MEMTYPE_PCACHE);
+  }
+  return p;
+}
+
+/*
+** Free an allocated buffer obtained from pcache1Alloc().
+*/
+static void pcache1Free(void *p){
+  if( p==0 ) return;
+  if( SQLITE_WITHIN(p, pcache1.pStart, pcache1.pEnd) ){
+    PgFreeslot *pSlot;
+    sqlite3_mutex_enter(pcache1.mutex);
+    sqlite3StatusDown(SQLITE_STATUS_PAGECACHE_USED, 1);
+    pSlot = (PgFreeslot*)p;
+    pSlot->pNext = pcache1.pFree;
+    pcache1.pFree = pSlot;
+    pcache1.nFreeSlot++;
+    pcache1.bUnderPressure = pcache1.nFreeSlot<pcache1.nReserve;
+    assert( pcache1.nFreeSlot<=pcache1.nSlot );
+    sqlite3_mutex_leave(pcache1.mutex);
+  }else{
+    assert( sqlite3MemdebugHasType(p, MEMTYPE_PCACHE) );
+    sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
+#ifndef SQLITE_DISABLE_PAGECACHE_OVERFLOW_STATS
+    {
+      int nFreed = 0;
+      nFreed = sqlite3MallocSize(p);
+      sqlite3_mutex_enter(pcache1.mutex);
+      sqlite3StatusDown(SQLITE_STATUS_PAGECACHE_OVERFLOW, nFreed);
+      sqlite3_mutex_leave(pcache1.mutex);
+    }
+#endif
+    sqlite3_free(p);
+  }
+}
+
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+/*
+** Return the size of a pcache allocation
+*/
+static int pcache1MemSize(void *p){
+  if( p>=pcache1.pStart && p<pcache1.pEnd ){
+    return pcache1.szSlot;
+  }else{
+    int iSize;
+    assert( sqlite3MemdebugHasType(p, MEMTYPE_PCACHE) );
+    sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
+    iSize = sqlite3MallocSize(p);
+    sqlite3MemdebugSetType(p, MEMTYPE_PCACHE);
+    return iSize;
+  }
+}
+#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */
+
+/*
+** Allocate a new page object initially associated with cache pCache.
+*/
+static PgHdr1 *pcache1AllocPage(PCache1 *pCache, int benignMalloc){
+  PgHdr1 *p = 0;
+  void *pPg;
+
+  assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
+  if( pCache->pFree || (pCache->nPage==0 && pcache1InitBulk(pCache)) ){
+    p = pCache->pFree;
+    pCache->pFree = p->pNext;
+    p->pNext = 0;
+  }else{
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+    /* The group mutex must be released before pcache1Alloc() is called. This
+    ** is because it might call sqlite3_release_memory(), which assumes that 
+    ** this mutex is not held. */
+    assert( pcache1.separateCache==0 );
+    assert( pCache->pGroup==&pcache1.grp );
+    pcache1LeaveMutex(pCache->pGroup);
+#endif
+    if( benignMalloc ){ sqlite3BeginBenignMalloc(); }
+#ifdef SQLITE_PCACHE_SEPARATE_HEADER
+    pPg = pcache1Alloc(pCache->szPage);
+    p = sqlite3Malloc(sizeof(PgHdr1) + pCache->szExtra);
+    if( !pPg || !p ){
+      pcache1Free(pPg);
+      sqlite3_free(p);
+      pPg = 0;
+    }
+#else
+    pPg = pcache1Alloc(pCache->szAlloc);
+    p = (PgHdr1 *)&((u8 *)pPg)[pCache->szPage];
+#endif
+    if( benignMalloc ){ sqlite3EndBenignMalloc(); }
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+    pcache1EnterMutex(pCache->pGroup);
+#endif
+    if( pPg==0 ) return 0;
+    p->page.pBuf = pPg;
+    p->page.pExtra = &p[1];
+    p->isBulkLocal = 0;
+    p->isAnchor = 0;
+  }
+  if( pCache->bPurgeable ){
+    pCache->pGroup->nCurrentPage++;
+  }
+  return p;
+}
+
+/*
+** Free a page object allocated by pcache1AllocPage().
+*/
+static void pcache1FreePage(PgHdr1 *p){
+  PCache1 *pCache;
+  assert( p!=0 );
+  pCache = p->pCache;
+  assert( sqlite3_mutex_held(p->pCache->pGroup->mutex) );
+  if( p->isBulkLocal ){
+    p->pNext = pCache->pFree;
+    pCache->pFree = p;
+  }else{
+    pcache1Free(p->page.pBuf);
+#ifdef SQLITE_PCACHE_SEPARATE_HEADER
+    sqlite3_free(p);
+#endif
+  }
+  if( pCache->bPurgeable ){
+    pCache->pGroup->nCurrentPage--;
+  }
+}
+
+/*
+** Malloc function used by SQLite to obtain space from the buffer configured
+** using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no such buffer
+** exists, this function falls back to sqlite3Malloc().
+*/
+SQLITE_PRIVATE void *sqlite3PageMalloc(int sz){
+  return pcache1Alloc(sz);
+}
+
+/*
+** Free an allocated buffer obtained from sqlite3PageMalloc().
+*/
+SQLITE_PRIVATE void sqlite3PageFree(void *p){
+  pcache1Free(p);
+}
+
+
+/*
+** Return true if it desirable to avoid allocating a new page cache
+** entry.
+**
+** If memory was allocated specifically to the page cache using
+** SQLITE_CONFIG_PAGECACHE but that memory has all been used, then
+** it is desirable to avoid allocating a new page cache entry because
+** presumably SQLITE_CONFIG_PAGECACHE was suppose to be sufficient
+** for all page cache needs and we should not need to spill the
+** allocation onto the heap.
+**
+** Or, the heap is used for all page cache memory but the heap is
+** under memory pressure, then again it is desirable to avoid
+** allocating a new page cache entry in order to avoid stressing
+** the heap even further.
+*/
+static int pcache1UnderMemoryPressure(PCache1 *pCache){
+  if( pcache1.nSlot && (pCache->szPage+pCache->szExtra)<=pcache1.szSlot ){
+    return pcache1.bUnderPressure;
+  }else{
+    return sqlite3HeapNearlyFull();
+  }
+}
+
+/******************************************************************************/
+/******** General Implementation Functions ************************************/
+
+/*
+** This function is used to resize the hash table used by the cache passed
+** as the first argument.
+**
+** The PCache mutex must be held when this function is called.
+*/
+static void pcache1ResizeHash(PCache1 *p){
+  PgHdr1 **apNew;
+  unsigned int nNew;
+  unsigned int i;
+
+  assert( sqlite3_mutex_held(p->pGroup->mutex) );
+
+  nNew = p->nHash*2;
+  if( nNew<256 ){
+    nNew = 256;
+  }
+
+  pcache1LeaveMutex(p->pGroup);
+  if( p->nHash ){ sqlite3BeginBenignMalloc(); }
+  apNew = (PgHdr1 **)sqlite3MallocZero(sizeof(PgHdr1 *)*nNew);
+  if( p->nHash ){ sqlite3EndBenignMalloc(); }
+  pcache1EnterMutex(p->pGroup);
+  if( apNew ){
+    for(i=0; i<p->nHash; i++){
+      PgHdr1 *pPage;
+      PgHdr1 *pNext = p->apHash[i];
+      while( (pPage = pNext)!=0 ){
+        unsigned int h = pPage->iKey % nNew;
+        pNext = pPage->pNext;
+        pPage->pNext = apNew[h];
+        apNew[h] = pPage;
+      }
+    }
+    sqlite3_free(p->apHash);
+    p->apHash = apNew;
+    p->nHash = nNew;
+  }
+}
+
+/*
+** This function is used internally to remove the page pPage from the 
+** PGroup LRU list, if is part of it. If pPage is not part of the PGroup
+** LRU list, then this function is a no-op.
+**
+** The PGroup mutex must be held when this function is called.
+*/
+static PgHdr1 *pcache1PinPage(PgHdr1 *pPage){
+  PCache1 *pCache;
+
+  assert( pPage!=0 );
+  assert( pPage->isPinned==0 );
+  pCache = pPage->pCache;
+  assert( pPage->pLruNext );
+  assert( pPage->pLruPrev );
+  assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
+  pPage->pLruPrev->pLruNext = pPage->pLruNext;
+  pPage->pLruNext->pLruPrev = pPage->pLruPrev;
+  pPage->pLruNext = 0;
+  pPage->pLruPrev = 0;
+  pPage->isPinned = 1;
+  assert( pPage->isAnchor==0 );
+  assert( pCache->pGroup->lru.isAnchor==1 );
+  pCache->nRecyclable--;
+  return pPage;
+}
+
+
+/*
+** Remove the page supplied as an argument from the hash table 
+** (PCache1.apHash structure) that it is currently stored in.
+** Also free the page if freePage is true.
+**
+** The PGroup mutex must be held when this function is called.
+*/
+static void pcache1RemoveFromHash(PgHdr1 *pPage, int freeFlag){
+  unsigned int h;
+  PCache1 *pCache = pPage->pCache;
+  PgHdr1 **pp;
+
+  assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
+  h = pPage->iKey % pCache->nHash;
+  for(pp=&pCache->apHash[h]; (*pp)!=pPage; pp=&(*pp)->pNext);
+  *pp = (*pp)->pNext;
+
+  pCache->nPage--;
+  if( freeFlag ) pcache1FreePage(pPage);
+}
+
+/*
+** If there are currently more than nMaxPage pages allocated, try
+** to recycle pages to reduce the number allocated to nMaxPage.
+*/
+static void pcache1EnforceMaxPage(PCache1 *pCache){
+  PGroup *pGroup = pCache->pGroup;
+  PgHdr1 *p;
+  assert( sqlite3_mutex_held(pGroup->mutex) );
+  while( pGroup->nCurrentPage>pGroup->nMaxPage
+      && (p=pGroup->lru.pLruPrev)->isAnchor==0
+  ){
+    assert( p->pCache->pGroup==pGroup );
+    assert( p->isPinned==0 );
+    pcache1PinPage(p);
+    pcache1RemoveFromHash(p, 1);
+  }
+  if( pCache->nPage==0 && pCache->pBulk ){
+    sqlite3_free(pCache->pBulk);
+    pCache->pBulk = pCache->pFree = 0;
+  }
+}
+
+/*
+** Discard all pages from cache pCache with a page number (key value) 
+** greater than or equal to iLimit. Any pinned pages that meet this 
+** criteria are unpinned before they are discarded.
+**
+** The PCache mutex must be held when this function is called.
+*/
+static void pcache1TruncateUnsafe(
+  PCache1 *pCache,             /* The cache to truncate */
+  unsigned int iLimit          /* Drop pages with this pgno or larger */
+){
+  TESTONLY( int nPage = 0; )  /* To assert pCache->nPage is correct */
+  unsigned int h, iStop;
+  assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
+  assert( pCache->iMaxKey >= iLimit );
+  assert( pCache->nHash > 0 );
+  if( pCache->iMaxKey - iLimit < pCache->nHash ){
+    /* If we are just shaving the last few pages off the end of the
+    ** cache, then there is no point in scanning the entire hash table.
+    ** Only scan those hash slots that might contain pages that need to
+    ** be removed. */
+    h = iLimit % pCache->nHash;
+    iStop = pCache->iMaxKey % pCache->nHash;
+    TESTONLY( nPage = -10; )  /* Disable the pCache->nPage validity check */
+  }else{
+    /* This is the general case where many pages are being removed.
+    ** It is necessary to scan the entire hash table */
+    h = pCache->nHash/2;
+    iStop = h - 1;
+  }
+  for(;;){
+    PgHdr1 **pp;
+    PgHdr1 *pPage;
+    assert( h<pCache->nHash );
+    pp = &pCache->apHash[h]; 
+    while( (pPage = *pp)!=0 ){
+      if( pPage->iKey>=iLimit ){
+        pCache->nPage--;
+        *pp = pPage->pNext;
+        if( !pPage->isPinned ) pcache1PinPage(pPage);
+        pcache1FreePage(pPage);
+      }else{
+        pp = &pPage->pNext;
+        TESTONLY( if( nPage>=0 ) nPage++; )
+      }
+    }
+    if( h==iStop ) break;
+    h = (h+1) % pCache->nHash;
+  }
+  assert( nPage<0 || pCache->nPage==(unsigned)nPage );
+}
+
+/******************************************************************************/
+/******** sqlite3_pcache Methods **********************************************/
+
+/*
+** Implementation of the sqlite3_pcache.xInit method.
+*/
+static int pcache1Init(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  assert( pcache1.isInit==0 );
+  memset(&pcache1, 0, sizeof(pcache1));
+
+
+  /*
+  ** The pcache1.separateCache variable is true if each PCache has its own
+  ** private PGroup (mode-1).  pcache1.separateCache is false if the single
+  ** PGroup in pcache1.grp is used for all page caches (mode-2).
+  **
+  **   *  Always use a unified cache (mode-2) if ENABLE_MEMORY_MANAGEMENT
+  **
+  **   *  Use a unified cache in single-threaded applications that have
+  **      configured a start-time buffer for use as page-cache memory using
+  **      sqlite3_config(SQLITE_CONFIG_PAGECACHE, pBuf, sz, N) with non-NULL 
+  **      pBuf argument.
+  **
+  **   *  Otherwise use separate caches (mode-1)
+  */
+#if defined(SQLITE_ENABLE_MEMORY_MANAGEMENT)
+  pcache1.separateCache = 0;
+#elif SQLITE_THREADSAFE
+  pcache1.separateCache = sqlite3GlobalConfig.pPage==0
+                          || sqlite3GlobalConfig.bCoreMutex>0;
+#else
+  pcache1.separateCache = sqlite3GlobalConfig.pPage==0;
+#endif
+
+#if SQLITE_THREADSAFE
+  if( sqlite3GlobalConfig.bCoreMutex ){
+    pcache1.grp.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU);
+    pcache1.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_PMEM);
+  }
+#endif
+  if( pcache1.separateCache
+   && sqlite3GlobalConfig.nPage!=0
+   && sqlite3GlobalConfig.pPage==0
+  ){
+    pcache1.nInitPage = sqlite3GlobalConfig.nPage;
+  }else{
+    pcache1.nInitPage = 0;
+  }
+  pcache1.grp.mxPinned = 10;
+  pcache1.isInit = 1;
+  return SQLITE_OK;
+}
+
+/*
+** Implementation of the sqlite3_pcache.xShutdown method.
+** Note that the static mutex allocated in xInit does 
+** not need to be freed.
+*/
+static void pcache1Shutdown(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  assert( pcache1.isInit!=0 );
+  memset(&pcache1, 0, sizeof(pcache1));
+}
+
+/* forward declaration */
+static void pcache1Destroy(sqlite3_pcache *p);
+
+/*
+** Implementation of the sqlite3_pcache.xCreate method.
+**
+** Allocate a new cache.
+*/
+static sqlite3_pcache *pcache1Create(int szPage, int szExtra, int bPurgeable){
+  PCache1 *pCache;      /* The newly created page cache */
+  PGroup *pGroup;       /* The group the new page cache will belong to */
+  int sz;               /* Bytes of memory required to allocate the new cache */
+
+  assert( (szPage & (szPage-1))==0 && szPage>=512 && szPage<=65536 );
+  assert( szExtra < 300 );
+
+  sz = sizeof(PCache1) + sizeof(PGroup)*pcache1.separateCache;
+  pCache = (PCache1 *)sqlite3MallocZero(sz);
+  if( pCache ){
+    if( pcache1.separateCache ){
+      pGroup = (PGroup*)&pCache[1];
+      pGroup->mxPinned = 10;
+    }else{
+      pGroup = &pcache1.grp;
+    }
+    if( pGroup->lru.isAnchor==0 ){
+      pGroup->lru.isAnchor = 1;
+      pGroup->lru.pLruPrev = pGroup->lru.pLruNext = &pGroup->lru;
+    }
+    pCache->pGroup = pGroup;
+    pCache->szPage = szPage;
+    pCache->szExtra = szExtra;
+    pCache->szAlloc = szPage + szExtra + ROUND8(sizeof(PgHdr1));
+    pCache->bPurgeable = (bPurgeable ? 1 : 0);
+    pcache1EnterMutex(pGroup);
+    pcache1ResizeHash(pCache);
+    if( bPurgeable ){
+      pCache->nMin = 10;
+      pGroup->nMinPage += pCache->nMin;
+      pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
+    }
+    pcache1LeaveMutex(pGroup);
+    if( pCache->nHash==0 ){
+      pcache1Destroy((sqlite3_pcache*)pCache);
+      pCache = 0;
+    }
+  }
+  return (sqlite3_pcache *)pCache;
+}
+
+/*
+** Implementation of the sqlite3_pcache.xCachesize method. 
+**
+** Configure the cache_size limit for a cache.
+*/
+static void pcache1Cachesize(sqlite3_pcache *p, int nMax){
+  PCache1 *pCache = (PCache1 *)p;
+  if( pCache->bPurgeable ){
+    PGroup *pGroup = pCache->pGroup;
+    pcache1EnterMutex(pGroup);
+    pGroup->nMaxPage += (nMax - pCache->nMax);
+    pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
+    pCache->nMax = nMax;
+    pCache->n90pct = pCache->nMax*9/10;
+    pcache1EnforceMaxPage(pCache);
+    pcache1LeaveMutex(pGroup);
+  }
+}
+
+/*
+** Implementation of the sqlite3_pcache.xShrink method. 
+**
+** Free up as much memory as possible.
+*/
+static void pcache1Shrink(sqlite3_pcache *p){
+  PCache1 *pCache = (PCache1*)p;
+  if( pCache->bPurgeable ){
+    PGroup *pGroup = pCache->pGroup;
+    int savedMaxPage;
+    pcache1EnterMutex(pGroup);
+    savedMaxPage = pGroup->nMaxPage;
+    pGroup->nMaxPage = 0;
+    pcache1EnforceMaxPage(pCache);
+    pGroup->nMaxPage = savedMaxPage;
+    pcache1LeaveMutex(pGroup);
+  }
+}
+
+/*
+** Implementation of the sqlite3_pcache.xPagecount method. 
+*/
+static int pcache1Pagecount(sqlite3_pcache *p){
+  int n;
+  PCache1 *pCache = (PCache1*)p;
+  pcache1EnterMutex(pCache->pGroup);
+  n = pCache->nPage;
+  pcache1LeaveMutex(pCache->pGroup);
+  return n;
+}
+
+
+/*
+** Implement steps 3, 4, and 5 of the pcache1Fetch() algorithm described
+** in the header of the pcache1Fetch() procedure.
+**
+** This steps are broken out into a separate procedure because they are
+** usually not needed, and by avoiding the stack initialization required
+** for these steps, the main pcache1Fetch() procedure can run faster.
+*/
+static SQLITE_NOINLINE PgHdr1 *pcache1FetchStage2(
+  PCache1 *pCache, 
+  unsigned int iKey, 
+  int createFlag
+){
+  unsigned int nPinned;
+  PGroup *pGroup = pCache->pGroup;
+  PgHdr1 *pPage = 0;
+
+  /* Step 3: Abort if createFlag is 1 but the cache is nearly full */
+  assert( pCache->nPage >= pCache->nRecyclable );
+  nPinned = pCache->nPage - pCache->nRecyclable;
+  assert( pGroup->mxPinned == pGroup->nMaxPage + 10 - pGroup->nMinPage );
+  assert( pCache->n90pct == pCache->nMax*9/10 );
+  if( createFlag==1 && (
+        nPinned>=pGroup->mxPinned
+     || nPinned>=pCache->n90pct
+     || (pcache1UnderMemoryPressure(pCache) && pCache->nRecyclable<nPinned)
+  )){
+    return 0;
+  }
+
+  if( pCache->nPage>=pCache->nHash ) pcache1ResizeHash(pCache);
+  assert( pCache->nHash>0 && pCache->apHash );
+
+  /* Step 4. Try to recycle a page. */
+  if( pCache->bPurgeable
+   && !pGroup->lru.pLruPrev->isAnchor
+   && ((pCache->nPage+1>=pCache->nMax) || pcache1UnderMemoryPressure(pCache))
+  ){
+    PCache1 *pOther;
+    pPage = pGroup->lru.pLruPrev;
+    assert( pPage->isPinned==0 );
+    pcache1RemoveFromHash(pPage, 0);
+    pcache1PinPage(pPage);
+    pOther = pPage->pCache;
+    if( pOther->szAlloc != pCache->szAlloc ){
+      pcache1FreePage(pPage);
+      pPage = 0;
+    }else{
+      pGroup->nCurrentPage -= (pOther->bPurgeable - pCache->bPurgeable);
+    }
+  }
+
+  /* Step 5. If a usable page buffer has still not been found, 
+  ** attempt to allocate a new one. 
+  */
+  if( !pPage ){
+    pPage = pcache1AllocPage(pCache, createFlag==1);
+  }
+
+  if( pPage ){
+    unsigned int h = iKey % pCache->nHash;
+    pCache->nPage++;
+    pPage->iKey = iKey;
+    pPage->pNext = pCache->apHash[h];
+    pPage->pCache = pCache;
+    pPage->pLruPrev = 0;
+    pPage->pLruNext = 0;
+    pPage->isPinned = 1;
+    *(void **)pPage->page.pExtra = 0;
+    pCache->apHash[h] = pPage;
+    if( iKey>pCache->iMaxKey ){
+      pCache->iMaxKey = iKey;
+    }
+  }
+  return pPage;
+}
+
+/*
+** Implementation of the sqlite3_pcache.xFetch method. 
+**
+** Fetch a page by key value.
+**
+** Whether or not a new page may be allocated by this function depends on
+** the value of the createFlag argument.  0 means do not allocate a new
+** page.  1 means allocate a new page if space is easily available.  2 
+** means to try really hard to allocate a new page.
+**
+** For a non-purgeable cache (a cache used as the storage for an in-memory
+** database) there is really no difference between createFlag 1 and 2.  So
+** the calling function (pcache.c) will never have a createFlag of 1 on
+** a non-purgeable cache.
+**
+** There are three different approaches to obtaining space for a page,
+** depending on the value of parameter createFlag (which may be 0, 1 or 2).
+**
+**   1. Regardless of the value of createFlag, the cache is searched for a 
+**      copy of the requested page. If one is found, it is returned.
+**
+**   2. If createFlag==0 and the page is not already in the cache, NULL is
+**      returned.
+**
+**   3. If createFlag is 1, and the page is not already in the cache, then
+**      return NULL (do not allocate a new page) if any of the following
+**      conditions are true:
+**
+**       (a) the number of pages pinned by the cache is greater than
+**           PCache1.nMax, or
+**
+**       (b) the number of pages pinned by the cache is greater than
+**           the sum of nMax for all purgeable caches, less the sum of 
+**           nMin for all other purgeable caches, or
+**
+**   4. If none of the first three conditions apply and the cache is marked
+**      as purgeable, and if one of the following is true:
+**
+**       (a) The number of pages allocated for the cache is already 
+**           PCache1.nMax, or
+**
+**       (b) The number of pages allocated for all purgeable caches is
+**           already equal to or greater than the sum of nMax for all
+**           purgeable caches,
+**
+**       (c) The system is under memory pressure and wants to avoid
+**           unnecessary pages cache entry allocations
+**
+**      then attempt to recycle a page from the LRU list. If it is the right
+**      size, return the recycled buffer. Otherwise, free the buffer and
+**      proceed to step 5. 
+**
+**   5. Otherwise, allocate and return a new page buffer.
+**
+** There are two versions of this routine.  pcache1FetchWithMutex() is
+** the general case.  pcache1FetchNoMutex() is a faster implementation for
+** the common case where pGroup->mutex is NULL.  The pcache1Fetch() wrapper
+** invokes the appropriate routine.
+*/
+static PgHdr1 *pcache1FetchNoMutex(
+  sqlite3_pcache *p, 
+  unsigned int iKey, 
+  int createFlag
+){
+  PCache1 *pCache = (PCache1 *)p;
+  PgHdr1 *pPage = 0;
+
+  /* Step 1: Search the hash table for an existing entry. */
+  pPage = pCache->apHash[iKey % pCache->nHash];
+  while( pPage && pPage->iKey!=iKey ){ pPage = pPage->pNext; }
+
+  /* Step 2: If the page was found in the hash table, then return it.
+  ** If the page was not in the hash table and createFlag is 0, abort.
+  ** Otherwise (page not in hash and createFlag!=0) continue with
+  ** subsequent steps to try to create the page. */
+  if( pPage ){
+    if( !pPage->isPinned ){
+      return pcache1PinPage(pPage);
+    }else{
+      return pPage;
+    }
+  }else if( createFlag ){
+    /* Steps 3, 4, and 5 implemented by this subroutine */
+    return pcache1FetchStage2(pCache, iKey, createFlag);
+  }else{
+    return 0;
+  }
+}
+#if PCACHE1_MIGHT_USE_GROUP_MUTEX
+static PgHdr1 *pcache1FetchWithMutex(
+  sqlite3_pcache *p, 
+  unsigned int iKey, 
+  int createFlag
+){
+  PCache1 *pCache = (PCache1 *)p;
+  PgHdr1 *pPage;
+
+  pcache1EnterMutex(pCache->pGroup);
+  pPage = pcache1FetchNoMutex(p, iKey, createFlag);
+  assert( pPage==0 || pCache->iMaxKey>=iKey );
+  pcache1LeaveMutex(pCache->pGroup);
+  return pPage;
+}
+#endif
+static sqlite3_pcache_page *pcache1Fetch(
+  sqlite3_pcache *p, 
+  unsigned int iKey, 
+  int createFlag
+){
+#if PCACHE1_MIGHT_USE_GROUP_MUTEX || defined(SQLITE_DEBUG)
+  PCache1 *pCache = (PCache1 *)p;
+#endif
+
+  assert( offsetof(PgHdr1,page)==0 );
+  assert( pCache->bPurgeable || createFlag!=1 );
+  assert( pCache->bPurgeable || pCache->nMin==0 );
+  assert( pCache->bPurgeable==0 || pCache->nMin==10 );
+  assert( pCache->nMin==0 || pCache->bPurgeable );
+  assert( pCache->nHash>0 );
+#if PCACHE1_MIGHT_USE_GROUP_MUTEX
+  if( pCache->pGroup->mutex ){
+    return (sqlite3_pcache_page*)pcache1FetchWithMutex(p, iKey, createFlag);
+  }else
+#endif
+  {
+    return (sqlite3_pcache_page*)pcache1FetchNoMutex(p, iKey, createFlag);
+  }
+}
+
+
+/*
+** Implementation of the sqlite3_pcache.xUnpin method.
+**
+** Mark a page as unpinned (eligible for asynchronous recycling).
+*/
+static void pcache1Unpin(
+  sqlite3_pcache *p, 
+  sqlite3_pcache_page *pPg, 
+  int reuseUnlikely
+){
+  PCache1 *pCache = (PCache1 *)p;
+  PgHdr1 *pPage = (PgHdr1 *)pPg;
+  PGroup *pGroup = pCache->pGroup;
+ 
+  assert( pPage->pCache==pCache );
+  pcache1EnterMutex(pGroup);
+
+  /* It is an error to call this function if the page is already 
+  ** part of the PGroup LRU list.
+  */
+  assert( pPage->pLruPrev==0 && pPage->pLruNext==0 );
+  assert( pPage->isPinned==1 );
+
+  if( reuseUnlikely || pGroup->nCurrentPage>pGroup->nMaxPage ){
+    pcache1RemoveFromHash(pPage, 1);
+  }else{
+    /* Add the page to the PGroup LRU list. */
+    PgHdr1 **ppFirst = &pGroup->lru.pLruNext;
+    pPage->pLruPrev = &pGroup->lru;
+    (pPage->pLruNext = *ppFirst)->pLruPrev = pPage;
+    *ppFirst = pPage;
+    pCache->nRecyclable++;
+    pPage->isPinned = 0;
+  }
+
+  pcache1LeaveMutex(pCache->pGroup);
+}
+
+/*
+** Implementation of the sqlite3_pcache.xRekey method. 
+*/
+static void pcache1Rekey(
+  sqlite3_pcache *p,
+  sqlite3_pcache_page *pPg,
+  unsigned int iOld,
+  unsigned int iNew
+){
+  PCache1 *pCache = (PCache1 *)p;
+  PgHdr1 *pPage = (PgHdr1 *)pPg;
+  PgHdr1 **pp;
+  unsigned int h; 
+  assert( pPage->iKey==iOld );
+  assert( pPage->pCache==pCache );
+
+  pcache1EnterMutex(pCache->pGroup);
+
+  h = iOld%pCache->nHash;
+  pp = &pCache->apHash[h];
+  while( (*pp)!=pPage ){
+    pp = &(*pp)->pNext;
+  }
+  *pp = pPage->pNext;
+
+  h = iNew%pCache->nHash;
+  pPage->iKey = iNew;
+  pPage->pNext = pCache->apHash[h];
+  pCache->apHash[h] = pPage;
+  if( iNew>pCache->iMaxKey ){
+    pCache->iMaxKey = iNew;
+  }
+
+  pcache1LeaveMutex(pCache->pGroup);
+}
+
+/*
+** Implementation of the sqlite3_pcache.xTruncate method. 
+**
+** Discard all unpinned pages in the cache with a page number equal to
+** or greater than parameter iLimit. Any pinned pages with a page number
+** equal to or greater than iLimit are implicitly unpinned.
+*/
+static void pcache1Truncate(sqlite3_pcache *p, unsigned int iLimit){
+  PCache1 *pCache = (PCache1 *)p;
+  pcache1EnterMutex(pCache->pGroup);
+  if( iLimit<=pCache->iMaxKey ){
+    pcache1TruncateUnsafe(pCache, iLimit);
+    pCache->iMaxKey = iLimit-1;
+  }
+  pcache1LeaveMutex(pCache->pGroup);
+}
+
+/*
+** Implementation of the sqlite3_pcache.xDestroy method. 
+**
+** Destroy a cache allocated using pcache1Create().
+*/
+static void pcache1Destroy(sqlite3_pcache *p){
+  PCache1 *pCache = (PCache1 *)p;
+  PGroup *pGroup = pCache->pGroup;
+  assert( pCache->bPurgeable || (pCache->nMax==0 && pCache->nMin==0) );
+  pcache1EnterMutex(pGroup);
+  if( pCache->nPage ) pcache1TruncateUnsafe(pCache, 0);
+  assert( pGroup->nMaxPage >= pCache->nMax );
+  pGroup->nMaxPage -= pCache->nMax;
+  assert( pGroup->nMinPage >= pCache->nMin );
+  pGroup->nMinPage -= pCache->nMin;
+  pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
+  pcache1EnforceMaxPage(pCache);
+  pcache1LeaveMutex(pGroup);
+  sqlite3_free(pCache->pBulk);
+  sqlite3_free(pCache->apHash);
+  sqlite3_free(pCache);
+}
+
+/*
+** This function is called during initialization (sqlite3_initialize()) to
+** install the default pluggable cache module, assuming the user has not
+** already provided an alternative.
+*/
+SQLITE_PRIVATE void sqlite3PCacheSetDefault(void){
+  static const sqlite3_pcache_methods2 defaultMethods = {
+    1,                       /* iVersion */
+    0,                       /* pArg */
+    pcache1Init,             /* xInit */
+    pcache1Shutdown,         /* xShutdown */
+    pcache1Create,           /* xCreate */
+    pcache1Cachesize,        /* xCachesize */
+    pcache1Pagecount,        /* xPagecount */
+    pcache1Fetch,            /* xFetch */
+    pcache1Unpin,            /* xUnpin */
+    pcache1Rekey,            /* xRekey */
+    pcache1Truncate,         /* xTruncate */
+    pcache1Destroy,          /* xDestroy */
+    pcache1Shrink            /* xShrink */
+  };
+  sqlite3_config(SQLITE_CONFIG_PCACHE2, &defaultMethods);
+}
+
+/*
+** Return the size of the header on each page of this PCACHE implementation.
+*/
+SQLITE_PRIVATE int sqlite3HeaderSizePcache1(void){ return ROUND8(sizeof(PgHdr1)); }
+
+/*
+** Return the global mutex used by this PCACHE implementation.  The
+** sqlite3_status() routine needs access to this mutex.
+*/
+SQLITE_PRIVATE sqlite3_mutex *sqlite3Pcache1Mutex(void){
+  return pcache1.mutex;
+}
+
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+/*
+** This function is called to free superfluous dynamically allocated memory
+** held by the pager system. Memory in use by any SQLite pager allocated
+** by the current thread may be sqlite3_free()ed.
+**
+** nReq is the number of bytes of memory required. Once this much has
+** been released, the function returns. The return value is the total number 
+** of bytes of memory released.
+*/
+SQLITE_PRIVATE int sqlite3PcacheReleaseMemory(int nReq){
+  int nFree = 0;
+  assert( sqlite3_mutex_notheld(pcache1.grp.mutex) );
+  assert( sqlite3_mutex_notheld(pcache1.mutex) );
+  if( sqlite3GlobalConfig.nPage==0 ){
+    PgHdr1 *p;
+    pcache1EnterMutex(&pcache1.grp);
+    while( (nReq<0 || nFree<nReq)
+       &&  (p=pcache1.grp.lru.pLruPrev)!=0
+       &&  p->isAnchor==0
+    ){
+      nFree += pcache1MemSize(p->page.pBuf);
+#ifdef SQLITE_PCACHE_SEPARATE_HEADER
+      nFree += sqlite3MemSize(p);
+#endif
+      assert( p->isPinned==0 );
+      pcache1PinPage(p);
+      pcache1RemoveFromHash(p, 1);
+    }
+    pcache1LeaveMutex(&pcache1.grp);
+  }
+  return nFree;
+}
+#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */
+
+#ifdef SQLITE_TEST
+/*
+** This function is used by test procedures to inspect the internal state
+** of the global cache.
+*/
+SQLITE_PRIVATE void sqlite3PcacheStats(
+  int *pnCurrent,      /* OUT: Total number of pages cached */
+  int *pnMax,          /* OUT: Global maximum cache size */
+  int *pnMin,          /* OUT: Sum of PCache1.nMin for purgeable caches */
+  int *pnRecyclable    /* OUT: Total number of pages available for recycling */
+){
+  PgHdr1 *p;
+  int nRecyclable = 0;
+  for(p=pcache1.grp.lru.pLruNext; p && !p->isAnchor; p=p->pLruNext){
+    assert( p->isPinned==0 );
+    nRecyclable++;
+  }
+  *pnCurrent = pcache1.grp.nCurrentPage;
+  *pnMax = (int)pcache1.grp.nMaxPage;
+  *pnMin = (int)pcache1.grp.nMinPage;
+  *pnRecyclable = nRecyclable;
+}
+#endif
+
+/************** End of pcache1.c *********************************************/
+/************** Begin file rowset.c ******************************************/
+/*
+** 2008 December 3
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This module implements an object we call a "RowSet".
+**
+** The RowSet object is a collection of rowids.  Rowids
+** are inserted into the RowSet in an arbitrary order.  Inserts
+** can be intermixed with tests to see if a given rowid has been
+** previously inserted into the RowSet.
+**
+** After all inserts are finished, it is possible to extract the
+** elements of the RowSet in sorted order.  Once this extraction
+** process has started, no new elements may be inserted.
+**
+** Hence, the primitive operations for a RowSet are:
+**
+**    CREATE
+**    INSERT
+**    TEST
+**    SMALLEST
+**    DESTROY
+**
+** The CREATE and DESTROY primitives are the constructor and destructor,
+** obviously.  The INSERT primitive adds a new element to the RowSet.
+** TEST checks to see if an element is already in the RowSet.  SMALLEST
+** extracts the least value from the RowSet.
+**
+** The INSERT primitive might allocate additional memory.  Memory is
+** allocated in chunks so most INSERTs do no allocation.  There is an 
+** upper bound on the size of allocated memory.  No memory is freed
+** until DESTROY.
+**
+** The TEST primitive includes a "batch" number.  The TEST primitive
+** will only see elements that were inserted before the last change
+** in the batch number.  In other words, if an INSERT occurs between
+** two TESTs where the TESTs have the same batch nubmer, then the
+** value added by the INSERT will not be visible to the second TEST.
+** The initial batch number is zero, so if the very first TEST contains
+** a non-zero batch number, it will see all prior INSERTs.
+**
+** No INSERTs may occurs after a SMALLEST.  An assertion will fail if
+** that is attempted.
+**
+** The cost of an INSERT is roughly constant.  (Sometimes new memory
+** has to be allocated on an INSERT.)  The cost of a TEST with a new
+** batch number is O(NlogN) where N is the number of elements in the RowSet.
+** The cost of a TEST using the same batch number is O(logN).  The cost
+** of the first SMALLEST is O(NlogN).  Second and subsequent SMALLEST
+** primitives are constant time.  The cost of DESTROY is O(N).
+**
+** TEST and SMALLEST may not be used by the same RowSet.  This used to
+** be possible, but the feature was not used, so it was removed in order
+** to simplify the code.
+*/
+/* #include "sqliteInt.h" */
+
+
+/*
+** Target size for allocation chunks.
+*/
+#define ROWSET_ALLOCATION_SIZE 1024
+
+/*
+** The number of rowset entries per allocation chunk.
+*/
+#define ROWSET_ENTRY_PER_CHUNK  \
+                       ((ROWSET_ALLOCATION_SIZE-8)/sizeof(struct RowSetEntry))
+
+/*
+** Each entry in a RowSet is an instance of the following object.
+**
+** This same object is reused to store a linked list of trees of RowSetEntry
+** objects.  In that alternative use, pRight points to the next entry
+** in the list, pLeft points to the tree, and v is unused.  The
+** RowSet.pForest value points to the head of this forest list.
+*/
+struct RowSetEntry {            
+  i64 v;                        /* ROWID value for this entry */
+  struct RowSetEntry *pRight;   /* Right subtree (larger entries) or list */
+  struct RowSetEntry *pLeft;    /* Left subtree (smaller entries) */
+};
+
+/*
+** RowSetEntry objects are allocated in large chunks (instances of the
+** following structure) to reduce memory allocation overhead.  The
+** chunks are kept on a linked list so that they can be deallocated
+** when the RowSet is destroyed.
+*/
+struct RowSetChunk {
+  struct RowSetChunk *pNextChunk;        /* Next chunk on list of them all */
+  struct RowSetEntry aEntry[ROWSET_ENTRY_PER_CHUNK]; /* Allocated entries */
+};
+
+/*
+** A RowSet in an instance of the following structure.
+**
+** A typedef of this structure if found in sqliteInt.h.
+*/
+struct RowSet {
+  struct RowSetChunk *pChunk;    /* List of all chunk allocations */
+  sqlite3 *db;                   /* The database connection */
+  struct RowSetEntry *pEntry;    /* List of entries using pRight */
+  struct RowSetEntry *pLast;     /* Last entry on the pEntry list */
+  struct RowSetEntry *pFresh;    /* Source of new entry objects */
+  struct RowSetEntry *pForest;   /* List of binary trees of entries */
+  u16 nFresh;                    /* Number of objects on pFresh */
+  u16 rsFlags;                   /* Various flags */
+  int iBatch;                    /* Current insert batch */
+};
+
+/*
+** Allowed values for RowSet.rsFlags
+*/
+#define ROWSET_SORTED  0x01   /* True if RowSet.pEntry is sorted */
+#define ROWSET_NEXT    0x02   /* True if sqlite3RowSetNext() has been called */
+
+/*
+** Turn bulk memory into a RowSet object.  N bytes of memory
+** are available at pSpace.  The db pointer is used as a memory context
+** for any subsequent allocations that need to occur.
+** Return a pointer to the new RowSet object.
+**
+** It must be the case that N is sufficient to make a Rowset.  If not
+** an assertion fault occurs.
+** 
+** If N is larger than the minimum, use the surplus as an initial
+** allocation of entries available to be filled.
+*/
+SQLITE_PRIVATE RowSet *sqlite3RowSetInit(sqlite3 *db, void *pSpace, unsigned int N){
+  RowSet *p;
+  assert( N >= ROUND8(sizeof(*p)) );
+  p = pSpace;
+  p->pChunk = 0;
+  p->db = db;
+  p->pEntry = 0;
+  p->pLast = 0;
+  p->pForest = 0;
+  p->pFresh = (struct RowSetEntry*)(ROUND8(sizeof(*p)) + (char*)p);
+  p->nFresh = (u16)((N - ROUND8(sizeof(*p)))/sizeof(struct RowSetEntry));
+  p->rsFlags = ROWSET_SORTED;
+  p->iBatch = 0;
+  return p;
+}
+
+/*
+** Deallocate all chunks from a RowSet.  This frees all memory that
+** the RowSet has allocated over its lifetime.  This routine is
+** the destructor for the RowSet.
+*/
+SQLITE_PRIVATE void sqlite3RowSetClear(RowSet *p){
+  struct RowSetChunk *pChunk, *pNextChunk;
+  for(pChunk=p->pChunk; pChunk; pChunk = pNextChunk){
+    pNextChunk = pChunk->pNextChunk;
+    sqlite3DbFree(p->db, pChunk);
+  }
+  p->pChunk = 0;
+  p->nFresh = 0;
+  p->pEntry = 0;
+  p->pLast = 0;
+  p->pForest = 0;
+  p->rsFlags = ROWSET_SORTED;
+}
+
+/*
+** Allocate a new RowSetEntry object that is associated with the
+** given RowSet.  Return a pointer to the new and completely uninitialized
+** objected.
+**
+** In an OOM situation, the RowSet.db->mallocFailed flag is set and this
+** routine returns NULL.
+*/
+static struct RowSetEntry *rowSetEntryAlloc(RowSet *p){
+  assert( p!=0 );
+  if( p->nFresh==0 ){  /*OPTIMIZATION-IF-FALSE*/
+    /* We could allocate a fresh RowSetEntry each time one is needed, but it
+    ** is more efficient to pull a preallocated entry from the pool */
+    struct RowSetChunk *pNew;
+    pNew = sqlite3DbMallocRawNN(p->db, sizeof(*pNew));
+    if( pNew==0 ){
+      return 0;
+    }
+    pNew->pNextChunk = p->pChunk;
+    p->pChunk = pNew;
+    p->pFresh = pNew->aEntry;
+    p->nFresh = ROWSET_ENTRY_PER_CHUNK;
+  }
+  p->nFresh--;
+  return p->pFresh++;
+}
+
+/*
+** Insert a new value into a RowSet.
+**
+** The mallocFailed flag of the database connection is set if a
+** memory allocation fails.
+*/
+SQLITE_PRIVATE void sqlite3RowSetInsert(RowSet *p, i64 rowid){
+  struct RowSetEntry *pEntry;  /* The new entry */
+  struct RowSetEntry *pLast;   /* The last prior entry */
+
+  /* This routine is never called after sqlite3RowSetNext() */
+  assert( p!=0 && (p->rsFlags & ROWSET_NEXT)==0 );
+
+  pEntry = rowSetEntryAlloc(p);
+  if( pEntry==0 ) return;
+  pEntry->v = rowid;
+  pEntry->pRight = 0;
+  pLast = p->pLast;
+  if( pLast ){
+    if( rowid<=pLast->v ){  /*OPTIMIZATION-IF-FALSE*/
+      /* Avoid unnecessary sorts by preserving the ROWSET_SORTED flags
+      ** where possible */
+      p->rsFlags &= ~ROWSET_SORTED;
+    }
+    pLast->pRight = pEntry;
+  }else{
+    p->pEntry = pEntry;
+  }
+  p->pLast = pEntry;
+}
+
+/*
+** Merge two lists of RowSetEntry objects.  Remove duplicates.
+**
+** The input lists are connected via pRight pointers and are 
+** assumed to each already be in sorted order.
+*/
+static struct RowSetEntry *rowSetEntryMerge(
+  struct RowSetEntry *pA,    /* First sorted list to be merged */
+  struct RowSetEntry *pB     /* Second sorted list to be merged */
+){
+  struct RowSetEntry head;
+  struct RowSetEntry *pTail;
+
+  pTail = &head;
+  assert( pA!=0 && pB!=0 );
+  for(;;){
+    assert( pA->pRight==0 || pA->v<=pA->pRight->v );
+    assert( pB->pRight==0 || pB->v<=pB->pRight->v );
+    if( pA->v<=pB->v ){
+      if( pA->v<pB->v ) pTail = pTail->pRight = pA;
+      pA = pA->pRight;
+      if( pA==0 ){
+        pTail->pRight = pB;
+        break;
+      }
+    }else{
+      pTail = pTail->pRight = pB;
+      pB = pB->pRight;
+      if( pB==0 ){
+        pTail->pRight = pA;
+        break;
+      }
+    }
+  }
+  return head.pRight;
+}
+
+/*
+** Sort all elements on the list of RowSetEntry objects into order of
+** increasing v.
+*/ 
+static struct RowSetEntry *rowSetEntrySort(struct RowSetEntry *pIn){
+  unsigned int i;
+  struct RowSetEntry *pNext, *aBucket[40];
+
+  memset(aBucket, 0, sizeof(aBucket));
+  while( pIn ){
+    pNext = pIn->pRight;
+    pIn->pRight = 0;
+    for(i=0; aBucket[i]; i++){
+      pIn = rowSetEntryMerge(aBucket[i], pIn);
+      aBucket[i] = 0;
+    }
+    aBucket[i] = pIn;
+    pIn = pNext;
+  }
+  pIn = aBucket[0];
+  for(i=1; i<sizeof(aBucket)/sizeof(aBucket[0]); i++){
+    if( aBucket[i]==0 ) continue;
+    pIn = pIn ? rowSetEntryMerge(pIn, aBucket[i]) : aBucket[i];
+  }
+  return pIn;
+}
+
+
+/*
+** The input, pIn, is a binary tree (or subtree) of RowSetEntry objects.
+** Convert this tree into a linked list connected by the pRight pointers
+** and return pointers to the first and last elements of the new list.
+*/
+static void rowSetTreeToList(
+  struct RowSetEntry *pIn,         /* Root of the input tree */
+  struct RowSetEntry **ppFirst,    /* Write head of the output list here */
+  struct RowSetEntry **ppLast      /* Write tail of the output list here */
+){
+  assert( pIn!=0 );
+  if( pIn->pLeft ){
+    struct RowSetEntry *p;
+    rowSetTreeToList(pIn->pLeft, ppFirst, &p);
+    p->pRight = pIn;
+  }else{
+    *ppFirst = pIn;
+  }
+  if( pIn->pRight ){
+    rowSetTreeToList(pIn->pRight, &pIn->pRight, ppLast);
+  }else{
+    *ppLast = pIn;
+  }
+  assert( (*ppLast)->pRight==0 );
+}
+
+
+/*
+** Convert a sorted list of elements (connected by pRight) into a binary
+** tree with depth of iDepth.  A depth of 1 means the tree contains a single
+** node taken from the head of *ppList.  A depth of 2 means a tree with
+** three nodes.  And so forth.
+**
+** Use as many entries from the input list as required and update the
+** *ppList to point to the unused elements of the list.  If the input
+** list contains too few elements, then construct an incomplete tree
+** and leave *ppList set to NULL.
+**
+** Return a pointer to the root of the constructed binary tree.
+*/
+static struct RowSetEntry *rowSetNDeepTree(
+  struct RowSetEntry **ppList,
+  int iDepth
+){
+  struct RowSetEntry *p;         /* Root of the new tree */
+  struct RowSetEntry *pLeft;     /* Left subtree */
+  if( *ppList==0 ){ /*OPTIMIZATION-IF-TRUE*/
+    /* Prevent unnecessary deep recursion when we run out of entries */
+    return 0; 
+  }
+  if( iDepth>1 ){   /*OPTIMIZATION-IF-TRUE*/
+    /* This branch causes a *balanced* tree to be generated.  A valid tree
+    ** is still generated without this branch, but the tree is wildly
+    ** unbalanced and inefficient. */
+    pLeft = rowSetNDeepTree(ppList, iDepth-1);
+    p = *ppList;
+    if( p==0 ){     /*OPTIMIZATION-IF-FALSE*/
+      /* It is safe to always return here, but the resulting tree
+      ** would be unbalanced */
+      return pLeft;
+    }
+    p->pLeft = pLeft;
+    *ppList = p->pRight;
+    p->pRight = rowSetNDeepTree(ppList, iDepth-1);
+  }else{
+    p = *ppList;
+    *ppList = p->pRight;
+    p->pLeft = p->pRight = 0;
+  }
+  return p;
+}
+
+/*
+** Convert a sorted list of elements into a binary tree. Make the tree
+** as deep as it needs to be in order to contain the entire list.
+*/
+static struct RowSetEntry *rowSetListToTree(struct RowSetEntry *pList){
+  int iDepth;           /* Depth of the tree so far */
+  struct RowSetEntry *p;       /* Current tree root */
+  struct RowSetEntry *pLeft;   /* Left subtree */
+
+  assert( pList!=0 );
+  p = pList;
+  pList = p->pRight;
+  p->pLeft = p->pRight = 0;
+  for(iDepth=1; pList; iDepth++){
+    pLeft = p;
+    p = pList;
+    pList = p->pRight;
+    p->pLeft = pLeft;
+    p->pRight = rowSetNDeepTree(&pList, iDepth);
+  }
+  return p;
+}
+
+/*
+** Extract the smallest element from the RowSet.
+** Write the element into *pRowid.  Return 1 on success.  Return
+** 0 if the RowSet is already empty.
+**
+** After this routine has been called, the sqlite3RowSetInsert()
+** routine may not be called again.
+**
+** This routine may not be called after sqlite3RowSetTest() has
+** been used.  Older versions of RowSet allowed that, but as the
+** capability was not used by the code generator, it was removed
+** for code economy.
+*/
+SQLITE_PRIVATE int sqlite3RowSetNext(RowSet *p, i64 *pRowid){
+  assert( p!=0 );
+  assert( p->pForest==0 );  /* Cannot be used with sqlite3RowSetText() */
+
+  /* Merge the forest into a single sorted list on first call */
+  if( (p->rsFlags & ROWSET_NEXT)==0 ){  /*OPTIMIZATION-IF-FALSE*/
+    if( (p->rsFlags & ROWSET_SORTED)==0 ){  /*OPTIMIZATION-IF-FALSE*/
+      p->pEntry = rowSetEntrySort(p->pEntry);
+    }
+    p->rsFlags |= ROWSET_SORTED|ROWSET_NEXT;
+  }
+
+  /* Return the next entry on the list */
+  if( p->pEntry ){
+    *pRowid = p->pEntry->v;
+    p->pEntry = p->pEntry->pRight;
+    if( p->pEntry==0 ){ /*OPTIMIZATION-IF-TRUE*/
+      /* Free memory immediately, rather than waiting on sqlite3_finalize() */
+      sqlite3RowSetClear(p);
+    }
+    return 1;
+  }else{
+    return 0;
+  }
+}
+
+/*
+** Check to see if element iRowid was inserted into the rowset as
+** part of any insert batch prior to iBatch.  Return 1 or 0.
+**
+** If this is the first test of a new batch and if there exist entries
+** on pRowSet->pEntry, then sort those entries into the forest at
+** pRowSet->pForest so that they can be tested.
+*/
+SQLITE_PRIVATE int sqlite3RowSetTest(RowSet *pRowSet, int iBatch, sqlite3_int64 iRowid){
+  struct RowSetEntry *p, *pTree;
+
+  /* This routine is never called after sqlite3RowSetNext() */
+  assert( pRowSet!=0 && (pRowSet->rsFlags & ROWSET_NEXT)==0 );
+
+  /* Sort entries into the forest on the first test of a new batch.
+  ** To save unnecessary work, only do this when the batch number changes.
+  */
+  if( iBatch!=pRowSet->iBatch ){  /*OPTIMIZATION-IF-FALSE*/
+    p = pRowSet->pEntry;
+    if( p ){
+      struct RowSetEntry **ppPrevTree = &pRowSet->pForest;
+      if( (pRowSet->rsFlags & ROWSET_SORTED)==0 ){ /*OPTIMIZATION-IF-FALSE*/
+        /* Only sort the current set of entiries if they need it */
+        p = rowSetEntrySort(p);
+      }
+      for(pTree = pRowSet->pForest; pTree; pTree=pTree->pRight){
+        ppPrevTree = &pTree->pRight;
+        if( pTree->pLeft==0 ){
+          pTree->pLeft = rowSetListToTree(p);
+          break;
+        }else{
+          struct RowSetEntry *pAux, *pTail;
+          rowSetTreeToList(pTree->pLeft, &pAux, &pTail);
+          pTree->pLeft = 0;
+          p = rowSetEntryMerge(pAux, p);
+        }
+      }
+      if( pTree==0 ){
+        *ppPrevTree = pTree = rowSetEntryAlloc(pRowSet);
+        if( pTree ){
+          pTree->v = 0;
+          pTree->pRight = 0;
+          pTree->pLeft = rowSetListToTree(p);
+        }
+      }
+      pRowSet->pEntry = 0;
+      pRowSet->pLast = 0;
+      pRowSet->rsFlags |= ROWSET_SORTED;
+    }
+    pRowSet->iBatch = iBatch;
+  }
+
+  /* Test to see if the iRowid value appears anywhere in the forest.
+  ** Return 1 if it does and 0 if not.
+  */
+  for(pTree = pRowSet->pForest; pTree; pTree=pTree->pRight){
+    p = pTree->pLeft;
+    while( p ){
+      if( p->v<iRowid ){
+        p = p->pRight;
+      }else if( p->v>iRowid ){
+        p = p->pLeft;
+      }else{
+        return 1;
+      }
+    }
+  }
+  return 0;
+}
+
+/************** End of rowset.c **********************************************/
+/************** Begin file pager.c *******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This is the implementation of the page cache subsystem or "pager".
+** 
+** The pager is used to access a database disk file.  It implements
+** atomic commit and rollback through the use of a journal file that
+** is separate from the database file.  The pager also implements file
+** locking to prevent two processes from writing the same database
+** file simultaneously, or one process from reading the database while
+** another is writing.
+*/
+#ifndef SQLITE_OMIT_DISKIO
+/* #include "sqliteInt.h" */
+/************** Include wal.h in the middle of pager.c ***********************/
+/************** Begin file wal.h *********************************************/
+/*
+** 2010 February 1
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This header file defines the interface to the write-ahead logging 
+** system. Refer to the comments below and the header comment attached to 
+** the implementation of each function in log.c for further details.
+*/
+
+#ifndef SQLITE_WAL_H
+#define SQLITE_WAL_H
+
+/* #include "sqliteInt.h" */
+
+/* Additional values that can be added to the sync_flags argument of
+** sqlite3WalFrames():
+*/
+#define WAL_SYNC_TRANSACTIONS  0x20   /* Sync at the end of each transaction */
+#define SQLITE_SYNC_MASK       0x13   /* Mask off the SQLITE_SYNC_* values */
+
+#ifdef SQLITE_OMIT_WAL
+# define sqlite3WalOpen(x,y,z)                   0
+# define sqlite3WalLimit(x,y)
+# define sqlite3WalClose(w,x,y,z)                0
+# define sqlite3WalBeginReadTransaction(y,z)     0
+# define sqlite3WalEndReadTransaction(z)
+# define sqlite3WalDbsize(y)                     0
+# define sqlite3WalBeginWriteTransaction(y)      0
+# define sqlite3WalEndWriteTransaction(x)        0
+# define sqlite3WalUndo(x,y,z)                   0
+# define sqlite3WalSavepoint(y,z)
+# define sqlite3WalSavepointUndo(y,z)            0
+# define sqlite3WalFrames(u,v,w,x,y,z)           0
+# define sqlite3WalCheckpoint(r,s,t,u,v,w,x,y,z) 0
+# define sqlite3WalCallback(z)                   0
+# define sqlite3WalExclusiveMode(y,z)            0
+# define sqlite3WalHeapMemory(z)                 0
+# define sqlite3WalFramesize(z)                  0
+# define sqlite3WalFindFrame(x,y,z)              0
+# define sqlite3WalFile(x)                       0
+#else
+
+#define WAL_SAVEPOINT_NDATA 4
+
+/* Connection to a write-ahead log (WAL) file. 
+** There is one object of this type for each pager. 
+*/
+typedef struct Wal Wal;
+
+/* Open and close a connection to a write-ahead log. */
+SQLITE_PRIVATE int sqlite3WalOpen(sqlite3_vfs*, sqlite3_file*, const char *, int, i64, Wal**);
+SQLITE_PRIVATE int sqlite3WalClose(Wal *pWal, int sync_flags, int, u8 *);
+
+/* Set the limiting size of a WAL file. */
+SQLITE_PRIVATE void sqlite3WalLimit(Wal*, i64);
+
+/* Used by readers to open (lock) and close (unlock) a snapshot.  A 
+** snapshot is like a read-transaction.  It is the state of the database
+** at an instant in time.  sqlite3WalOpenSnapshot gets a read lock and
+** preserves the current state even if the other threads or processes
+** write to or checkpoint the WAL.  sqlite3WalCloseSnapshot() closes the
+** transaction and releases the lock.
+*/
+SQLITE_PRIVATE int sqlite3WalBeginReadTransaction(Wal *pWal, int *);
+SQLITE_PRIVATE void sqlite3WalEndReadTransaction(Wal *pWal);
+
+/* Read a page from the write-ahead log, if it is present. */
+SQLITE_PRIVATE int sqlite3WalFindFrame(Wal *, Pgno, u32 *);
+SQLITE_PRIVATE int sqlite3WalReadFrame(Wal *, u32, int, u8 *);
+
+/* If the WAL is not empty, return the size of the database. */
+SQLITE_PRIVATE Pgno sqlite3WalDbsize(Wal *pWal);
+
+/* Obtain or release the WRITER lock. */
+SQLITE_PRIVATE int sqlite3WalBeginWriteTransaction(Wal *pWal);
+SQLITE_PRIVATE int sqlite3WalEndWriteTransaction(Wal *pWal);
+
+/* Undo any frames written (but not committed) to the log */
+SQLITE_PRIVATE int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), void *pUndoCtx);
+
+/* Return an integer that records the current (uncommitted) write
+** position in the WAL */
+SQLITE_PRIVATE void sqlite3WalSavepoint(Wal *pWal, u32 *aWalData);
+
+/* Move the write position of the WAL back to iFrame.  Called in
+** response to a ROLLBACK TO command. */
+SQLITE_PRIVATE int sqlite3WalSavepointUndo(Wal *pWal, u32 *aWalData);
+
+/* Write a frame or frames to the log. */
+SQLITE_PRIVATE int sqlite3WalFrames(Wal *pWal, int, PgHdr *, Pgno, int, int);
+
+/* Copy pages from the log to the database file */ 
+SQLITE_PRIVATE int sqlite3WalCheckpoint(
+  Wal *pWal,                      /* Write-ahead log connection */
+  int eMode,                      /* One of PASSIVE, FULL and RESTART */
+  int (*xBusy)(void*),            /* Function to call when busy */
+  void *pBusyArg,                 /* Context argument for xBusyHandler */
+  int sync_flags,                 /* Flags to sync db file with (or 0) */
+  int nBuf,                       /* Size of buffer nBuf */
+  u8 *zBuf,                       /* Temporary buffer to use */
+  int *pnLog,                     /* OUT: Number of frames in WAL */
+  int *pnCkpt                     /* OUT: Number of backfilled frames in WAL */
+);
+
+/* Return the value to pass to a sqlite3_wal_hook callback, the
+** number of frames in the WAL at the point of the last commit since
+** sqlite3WalCallback() was called.  If no commits have occurred since
+** the last call, then return 0.
+*/
+SQLITE_PRIVATE int sqlite3WalCallback(Wal *pWal);
+
+/* Tell the wal layer that an EXCLUSIVE lock has been obtained (or released)
+** by the pager layer on the database file.
+*/
+SQLITE_PRIVATE int sqlite3WalExclusiveMode(Wal *pWal, int op);
+
+/* Return true if the argument is non-NULL and the WAL module is using
+** heap-memory for the wal-index. Otherwise, if the argument is NULL or the
+** WAL module is using shared-memory, return false. 
+*/
+SQLITE_PRIVATE int sqlite3WalHeapMemory(Wal *pWal);
+
+#ifdef SQLITE_ENABLE_SNAPSHOT
+SQLITE_PRIVATE int sqlite3WalSnapshotGet(Wal *pWal, sqlite3_snapshot **ppSnapshot);
+SQLITE_PRIVATE void sqlite3WalSnapshotOpen(Wal *pWal, sqlite3_snapshot *pSnapshot);
+#endif
+
+#ifdef SQLITE_ENABLE_ZIPVFS
+/* If the WAL file is not empty, return the number of bytes of content
+** stored in each frame (i.e. the db page-size when the WAL was created).
+*/
+SQLITE_PRIVATE int sqlite3WalFramesize(Wal *pWal);
+#endif
+
+/* Return the sqlite3_file object for the WAL file */
+SQLITE_PRIVATE sqlite3_file *sqlite3WalFile(Wal *pWal);
+
+#endif /* ifndef SQLITE_OMIT_WAL */
+#endif /* SQLITE_WAL_H */
+
+/************** End of wal.h *************************************************/
+/************** Continuing where we left off in pager.c **********************/
+
+
+/******************* NOTES ON THE DESIGN OF THE PAGER ************************
+**
+** This comment block describes invariants that hold when using a rollback
+** journal.  These invariants do not apply for journal_mode=WAL,
+** journal_mode=MEMORY, or journal_mode=OFF.
+**
+** Within this comment block, a page is deemed to have been synced
+** automatically as soon as it is written when PRAGMA synchronous=OFF.
+** Otherwise, the page is not synced until the xSync method of the VFS
+** is called successfully on the file containing the page.
+**
+** Definition:  A page of the database file is said to be "overwriteable" if
+** one or more of the following are true about the page:
+** 
+**     (a)  The original content of the page as it was at the beginning of
+**          the transaction has been written into the rollback journal and
+**          synced.
+** 
+**     (b)  The page was a freelist leaf page at the start of the transaction.
+** 
+**     (c)  The page number is greater than the largest page that existed in
+**          the database file at the start of the transaction.
+** 
+** (1) A page of the database file is never overwritten unless one of the
+**     following are true:
+** 
+**     (a) The page and all other pages on the same sector are overwriteable.
+** 
+**     (b) The atomic page write optimization is enabled, and the entire
+**         transaction other than the update of the transaction sequence
+**         number consists of a single page change.
+** 
+** (2) The content of a page written into the rollback journal exactly matches
+**     both the content in the database when the rollback journal was written
+**     and the content in the database at the beginning of the current
+**     transaction.
+** 
+** (3) Writes to the database file are an integer multiple of the page size
+**     in length and are aligned on a page boundary.
+** 
+** (4) Reads from the database file are either aligned on a page boundary and
+**     an integer multiple of the page size in length or are taken from the
+**     first 100 bytes of the database file.
+** 
+** (5) All writes to the database file are synced prior to the rollback journal
+**     being deleted, truncated, or zeroed.
+** 
+** (6) If a master journal file is used, then all writes to the database file
+**     are synced prior to the master journal being deleted.
+** 
+** Definition: Two databases (or the same database at two points it time)
+** are said to be "logically equivalent" if they give the same answer to
+** all queries.  Note in particular the content of freelist leaf
+** pages can be changed arbitrarily without affecting the logical equivalence
+** of the database.
+** 
+** (7) At any time, if any subset, including the empty set and the total set,
+**     of the unsynced changes to a rollback journal are removed and the 
+**     journal is rolled back, the resulting database file will be logically
+**     equivalent to the database file at the beginning of the transaction.
+** 
+** (8) When a transaction is rolled back, the xTruncate method of the VFS
+**     is called to restore the database file to the same size it was at
+**     the beginning of the transaction.  (In some VFSes, the xTruncate
+**     method is a no-op, but that does not change the fact the SQLite will
+**     invoke it.)
+** 
+** (9) Whenever the database file is modified, at least one bit in the range
+**     of bytes from 24 through 39 inclusive will be changed prior to releasing
+**     the EXCLUSIVE lock, thus signaling other connections on the same
+**     database to flush their caches.
+**
+** (10) The pattern of bits in bytes 24 through 39 shall not repeat in less
+**      than one billion transactions.
+**
+** (11) A database file is well-formed at the beginning and at the conclusion
+**      of every transaction.
+**
+** (12) An EXCLUSIVE lock is held on the database file when writing to
+**      the database file.
+**
+** (13) A SHARED lock is held on the database file while reading any
+**      content out of the database file.
+**
+******************************************************************************/
+
+/*
+** Macros for troubleshooting.  Normally turned off
+*/
+#if 0
+int sqlite3PagerTrace=1;  /* True to enable tracing */
+#define sqlite3DebugPrintf printf
+#define PAGERTRACE(X)     if( sqlite3PagerTrace ){ sqlite3DebugPrintf X; }
+#else
+#define PAGERTRACE(X)
+#endif
+
+/*
+** The following two macros are used within the PAGERTRACE() macros above
+** to print out file-descriptors. 
+**
+** PAGERID() takes a pointer to a Pager struct as its argument. The
+** associated file-descriptor is returned. FILEHANDLEID() takes an sqlite3_file
+** struct as its argument.
+*/
+#define PAGERID(p) ((int)(p->fd))
+#define FILEHANDLEID(fd) ((int)fd)
+
+/*
+** The Pager.eState variable stores the current 'state' of a pager. A
+** pager may be in any one of the seven states shown in the following
+** state diagram.
+**
+**                            OPEN <------+------+
+**                              |         |      |
+**                              V         |      |
+**               +---------> READER-------+      |
+**               |              |                |
+**               |              V                |
+**               |<-------WRITER_LOCKED------> ERROR
+**               |              |                ^  
+**               |              V                |
+**               |<------WRITER_CACHEMOD-------->|
+**               |              |                |
+**               |              V                |
+**               |<-------WRITER_DBMOD---------->|
+**               |              |                |
+**               |              V                |
+**               +<------WRITER_FINISHED-------->+
+**
+**
+** List of state transitions and the C [function] that performs each:
+** 
+**   OPEN              -> READER              [sqlite3PagerSharedLock]
+**   READER            -> OPEN                [pager_unlock]
+**
+**   READER            -> WRITER_LOCKED       [sqlite3PagerBegin]
+**   WRITER_LOCKED     -> WRITER_CACHEMOD     [pager_open_journal]
+**   WRITER_CACHEMOD   -> WRITER_DBMOD        [syncJournal]
+**   WRITER_DBMOD      -> WRITER_FINISHED     [sqlite3PagerCommitPhaseOne]
+**   WRITER_***        -> READER              [pager_end_transaction]
+**
+**   WRITER_***        -> ERROR               [pager_error]
+**   ERROR             -> OPEN                [pager_unlock]
+** 
+**
+**  OPEN:
+**
+**    The pager starts up in this state. Nothing is guaranteed in this
+**    state - the file may or may not be locked and the database size is
+**    unknown. The database may not be read or written.
+**
+**    * No read or write transaction is active.
+**    * Any lock, or no lock at all, may be held on the database file.
+**    * The dbSize, dbOrigSize and dbFileSize variables may not be trusted.
+**
+**  READER:
+**
+**    In this state all the requirements for reading the database in 
+**    rollback (non-WAL) mode are met. Unless the pager is (or recently
+**    was) in exclusive-locking mode, a user-level read transaction is 
+**    open. The database size is known in this state.
+**
+**    A connection running with locking_mode=normal enters this state when
+**    it opens a read-transaction on the database and returns to state
+**    OPEN after the read-transaction is completed. However a connection
+**    running in locking_mode=exclusive (including temp databases) remains in
+**    this state even after the read-transaction is closed. The only way
+**    a locking_mode=exclusive connection can transition from READER to OPEN
+**    is via the ERROR state (see below).
+** 
+**    * A read transaction may be active (but a write-transaction cannot).
+**    * A SHARED or greater lock is held on the database file.
+**    * The dbSize variable may be trusted (even if a user-level read 
+**      transaction is not active). The dbOrigSize and dbFileSize variables
+**      may not be trusted at this point.
+**    * If the database is a WAL database, then the WAL connection is open.
+**    * Even if a read-transaction is not open, it is guaranteed that 
+**      there is no hot-journal in the file-system.
+**
+**  WRITER_LOCKED:
+**
+**    The pager moves to this state from READER when a write-transaction
+**    is first opened on the database. In WRITER_LOCKED state, all locks 
+**    required to start a write-transaction are held, but no actual 
+**    modifications to the cache or database have taken place.
+**
+**    In rollback mode, a RESERVED or (if the transaction was opened with 
+**    BEGIN EXCLUSIVE) EXCLUSIVE lock is obtained on the database file when
+**    moving to this state, but the journal file is not written to or opened 
+**    to in this state. If the transaction is committed or rolled back while 
+**    in WRITER_LOCKED state, all that is required is to unlock the database 
+**    file.
+**
+**    IN WAL mode, WalBeginWriteTransaction() is called to lock the log file.
+**    If the connection is running with locking_mode=exclusive, an attempt
+**    is made to obtain an EXCLUSIVE lock on the database file.
+**
+**    * A write transaction is active.
+**    * If the connection is open in rollback-mode, a RESERVED or greater 
+**      lock is held on the database file.
+**    * If the connection is open in WAL-mode, a WAL write transaction
+**      is open (i.e. sqlite3WalBeginWriteTransaction() has been successfully
+**      called).
+**    * The dbSize, dbOrigSize and dbFileSize variables are all valid.
+**    * The contents of the pager cache have not been modified.
+**    * The journal file may or may not be open.
+**    * Nothing (not even the first header) has been written to the journal.
+**
+**  WRITER_CACHEMOD:
+**
+**    A pager moves from WRITER_LOCKED state to this state when a page is
+**    first modified by the upper layer. In rollback mode the journal file
+**    is opened (if it is not already open) and a header written to the
+**    start of it. The database file on disk has not been modified.
+**
+**    * A write transaction is active.
+**    * A RESERVED or greater lock is held on the database file.
+**    * The journal file is open and the first header has been written 
+**      to it, but the header has not been synced to disk.
+**    * The contents of the page cache have been modified.
+**
+**  WRITER_DBMOD:
+**
+**    The pager transitions from WRITER_CACHEMOD into WRITER_DBMOD state
+**    when it modifies the contents of the database file. WAL connections
+**    never enter this state (since they do not modify the database file,
+**    just the log file).
+**
+**    * A write transaction is active.
+**    * An EXCLUSIVE or greater lock is held on the database file.
+**    * The journal file is open and the first header has been written 
+**      and synced to disk.
+**    * The contents of the page cache have been modified (and possibly
+**      written to disk).
+**
+**  WRITER_FINISHED:
+**
+**    It is not possible for a WAL connection to enter this state.
+**
+**    A rollback-mode pager changes to WRITER_FINISHED state from WRITER_DBMOD
+**    state after the entire transaction has been successfully written into the
+**    database file. In this state the transaction may be committed simply
+**    by finalizing the journal file. Once in WRITER_FINISHED state, it is 
+**    not possible to modify the database further. At this point, the upper 
+**    layer must either commit or rollback the transaction.
+**
+**    * A write transaction is active.
+**    * An EXCLUSIVE or greater lock is held on the database file.
+**    * All writing and syncing of journal and database data has finished.
+**      If no error occurred, all that remains is to finalize the journal to
+**      commit the transaction. If an error did occur, the caller will need
+**      to rollback the transaction. 
+**
+**  ERROR:
+**
+**    The ERROR state is entered when an IO or disk-full error (including
+**    SQLITE_IOERR_NOMEM) occurs at a point in the code that makes it 
+**    difficult to be sure that the in-memory pager state (cache contents, 
+**    db size etc.) are consistent with the contents of the file-system.
+**
+**    Temporary pager files may enter the ERROR state, but in-memory pagers
+**    cannot.
+**
+**    For example, if an IO error occurs while performing a rollback, 
+**    the contents of the page-cache may be left in an inconsistent state.
+**    At this point it would be dangerous to change back to READER state
+**    (as usually happens after a rollback). Any subsequent readers might
+**    report database corruption (due to the inconsistent cache), and if
+**    they upgrade to writers, they may inadvertently corrupt the database
+**    file. To avoid this hazard, the pager switches into the ERROR state
+**    instead of READER following such an error.
+**
+**    Once it has entered the ERROR state, any attempt to use the pager
+**    to read or write data returns an error. Eventually, once all 
+**    outstanding transactions have been abandoned, the pager is able to
+**    transition back to OPEN state, discarding the contents of the 
+**    page-cache and any other in-memory state at the same time. Everything
+**    is reloaded from disk (and, if necessary, hot-journal rollback peformed)
+**    when a read-transaction is next opened on the pager (transitioning
+**    the pager into READER state). At that point the system has recovered 
+**    from the error.
+**
+**    Specifically, the pager jumps into the ERROR state if:
+**
+**      1. An error occurs while attempting a rollback. This happens in
+**         function sqlite3PagerRollback().
+**
+**      2. An error occurs while attempting to finalize a journal file
+**         following a commit in function sqlite3PagerCommitPhaseTwo().
+**
+**      3. An error occurs while attempting to write to the journal or
+**         database file in function pagerStress() in order to free up
+**         memory.
+**
+**    In other cases, the error is returned to the b-tree layer. The b-tree
+**    layer then attempts a rollback operation. If the error condition 
+**    persists, the pager enters the ERROR state via condition (1) above.
+**
+**    Condition (3) is necessary because it can be triggered by a read-only
+**    statement executed within a transaction. In this case, if the error
+**    code were simply returned to the user, the b-tree layer would not
+**    automatically attempt a rollback, as it assumes that an error in a
+**    read-only statement cannot leave the pager in an internally inconsistent 
+**    state.
+**
+**    * The Pager.errCode variable is set to something other than SQLITE_OK.
+**    * There are one or more outstanding references to pages (after the
+**      last reference is dropped the pager should move back to OPEN state).
+**    * The pager is not an in-memory pager.
+**    
+**
+** Notes:
+**
+**   * A pager is never in WRITER_DBMOD or WRITER_FINISHED state if the
+**     connection is open in WAL mode. A WAL connection is always in one
+**     of the first four states.
+**
+**   * Normally, a connection open in exclusive mode is never in PAGER_OPEN
+**     state. There are two exceptions: immediately after exclusive-mode has
+**     been turned on (and before any read or write transactions are 
+**     executed), and when the pager is leaving the "error state".
+**
+**   * See also: assert_pager_state().
+*/
+#define PAGER_OPEN                  0
+#define PAGER_READER                1
+#define PAGER_WRITER_LOCKED         2
+#define PAGER_WRITER_CACHEMOD       3
+#define PAGER_WRITER_DBMOD          4
+#define PAGER_WRITER_FINISHED       5
+#define PAGER_ERROR                 6
+
+/*
+** The Pager.eLock variable is almost always set to one of the 
+** following locking-states, according to the lock currently held on
+** the database file: NO_LOCK, SHARED_LOCK, RESERVED_LOCK or EXCLUSIVE_LOCK.
+** This variable is kept up to date as locks are taken and released by
+** the pagerLockDb() and pagerUnlockDb() wrappers.
+**
+** If the VFS xLock() or xUnlock() returns an error other than SQLITE_BUSY
+** (i.e. one of the SQLITE_IOERR subtypes), it is not clear whether or not
+** the operation was successful. In these circumstances pagerLockDb() and
+** pagerUnlockDb() take a conservative approach - eLock is always updated
+** when unlocking the file, and only updated when locking the file if the
+** VFS call is successful. This way, the Pager.eLock variable may be set
+** to a less exclusive (lower) value than the lock that is actually held
+** at the system level, but it is never set to a more exclusive value.
+**
+** This is usually safe. If an xUnlock fails or appears to fail, there may 
+** be a few redundant xLock() calls or a lock may be held for longer than
+** required, but nothing really goes wrong.
+**
+** The exception is when the database file is unlocked as the pager moves
+** from ERROR to OPEN state. At this point there may be a hot-journal file 
+** in the file-system that needs to be rolled back (as part of an OPEN->SHARED
+** transition, by the same pager or any other). If the call to xUnlock()
+** fails at this point and the pager is left holding an EXCLUSIVE lock, this
+** can confuse the call to xCheckReservedLock() call made later as part
+** of hot-journal detection.
+**
+** xCheckReservedLock() is defined as returning true "if there is a RESERVED 
+** lock held by this process or any others". So xCheckReservedLock may 
+** return true because the caller itself is holding an EXCLUSIVE lock (but
+** doesn't know it because of a previous error in xUnlock). If this happens
+** a hot-journal may be mistaken for a journal being created by an active
+** transaction in another process, causing SQLite to read from the database
+** without rolling it back.
+**
+** To work around this, if a call to xUnlock() fails when unlocking the
+** database in the ERROR state, Pager.eLock is set to UNKNOWN_LOCK. It
+** is only changed back to a real locking state after a successful call
+** to xLock(EXCLUSIVE). Also, the code to do the OPEN->SHARED state transition
+** omits the check for a hot-journal if Pager.eLock is set to UNKNOWN_LOCK 
+** lock. Instead, it assumes a hot-journal exists and obtains an EXCLUSIVE
+** lock on the database file before attempting to roll it back. See function
+** PagerSharedLock() for more detail.
+**
+** Pager.eLock may only be set to UNKNOWN_LOCK when the pager is in 
+** PAGER_OPEN state.
+*/
+#define UNKNOWN_LOCK                (EXCLUSIVE_LOCK+1)
+
+/*
+** A macro used for invoking the codec if there is one
+*/
+#ifdef SQLITE_HAS_CODEC
+# define CODEC1(P,D,N,X,E) \
+    if( P->xCodec && P->xCodec(P->pCodec,D,N,X)==0 ){ E; }
+# define CODEC2(P,D,N,X,E,O) \
+    if( P->xCodec==0 ){ O=(char*)D; }else \
+    if( (O=(char*)(P->xCodec(P->pCodec,D,N,X)))==0 ){ E; }
+#else
+# define CODEC1(P,D,N,X,E)   /* NO-OP */
+# define CODEC2(P,D,N,X,E,O) O=(char*)D
+#endif
+
+/*
+** The maximum allowed sector size. 64KiB. If the xSectorsize() method 
+** returns a value larger than this, then MAX_SECTOR_SIZE is used instead.
+** This could conceivably cause corruption following a power failure on
+** such a system. This is currently an undocumented limit.
+*/
+#define MAX_SECTOR_SIZE 0x10000
+
+
+/*
+** An instance of the following structure is allocated for each active
+** savepoint and statement transaction in the system. All such structures
+** are stored in the Pager.aSavepoint[] array, which is allocated and
+** resized using sqlite3Realloc().
+**
+** When a savepoint is created, the PagerSavepoint.iHdrOffset field is
+** set to 0. If a journal-header is written into the main journal while
+** the savepoint is active, then iHdrOffset is set to the byte offset 
+** immediately following the last journal record written into the main
+** journal before the journal-header. This is required during savepoint
+** rollback (see pagerPlaybackSavepoint()).
+*/
+typedef struct PagerSavepoint PagerSavepoint;
+struct PagerSavepoint {
+  i64 iOffset;                 /* Starting offset in main journal */
+  i64 iHdrOffset;              /* See above */
+  Bitvec *pInSavepoint;        /* Set of pages in this savepoint */
+  Pgno nOrig;                  /* Original number of pages in file */
+  Pgno iSubRec;                /* Index of first record in sub-journal */
+#ifndef SQLITE_OMIT_WAL
+  u32 aWalData[WAL_SAVEPOINT_NDATA];        /* WAL savepoint context */
+#endif
+};
+
+/*
+** Bits of the Pager.doNotSpill flag.  See further description below.
+*/
+#define SPILLFLAG_OFF         0x01 /* Never spill cache.  Set via pragma */
+#define SPILLFLAG_ROLLBACK    0x02 /* Current rolling back, so do not spill */
+#define SPILLFLAG_NOSYNC      0x04 /* Spill is ok, but do not sync */
+
+/*
+** An open page cache is an instance of struct Pager. A description of
+** some of the more important member variables follows:
+**
+** eState
+**
+**   The current 'state' of the pager object. See the comment and state
+**   diagram above for a description of the pager state.
+**
+** eLock
+**
+**   For a real on-disk database, the current lock held on the database file -
+**   NO_LOCK, SHARED_LOCK, RESERVED_LOCK or EXCLUSIVE_LOCK.
+**
+**   For a temporary or in-memory database (neither of which require any
+**   locks), this variable is always set to EXCLUSIVE_LOCK. Since such
+**   databases always have Pager.exclusiveMode==1, this tricks the pager
+**   logic into thinking that it already has all the locks it will ever
+**   need (and no reason to release them).
+**
+**   In some (obscure) circumstances, this variable may also be set to
+**   UNKNOWN_LOCK. See the comment above the #define of UNKNOWN_LOCK for
+**   details.
+**
+** changeCountDone
+**
+**   This boolean variable is used to make sure that the change-counter 
+**   (the 4-byte header field at byte offset 24 of the database file) is 
+**   not updated more often than necessary. 
+**
+**   It is set to true when the change-counter field is updated, which 
+**   can only happen if an exclusive lock is held on the database file.
+**   It is cleared (set to false) whenever an exclusive lock is 
+**   relinquished on the database file. Each time a transaction is committed,
+**   The changeCountDone flag is inspected. If it is true, the work of
+**   updating the change-counter is omitted for the current transaction.
+**
+**   This mechanism means that when running in exclusive mode, a connection 
+**   need only update the change-counter once, for the first transaction
+**   committed.
+**
+** setMaster
+**
+**   When PagerCommitPhaseOne() is called to commit a transaction, it may
+**   (or may not) specify a master-journal name to be written into the 
+**   journal file before it is synced to disk.
+**
+**   Whether or not a journal file contains a master-journal pointer affects 
+**   the way in which the journal file is finalized after the transaction is 
+**   committed or rolled back when running in "journal_mode=PERSIST" mode.
+**   If a journal file does not contain a master-journal pointer, it is
+**   finalized by overwriting the first journal header with zeroes. If
+**   it does contain a master-journal pointer the journal file is finalized 
+**   by truncating it to zero bytes, just as if the connection were 
+**   running in "journal_mode=truncate" mode.
+**
+**   Journal files that contain master journal pointers cannot be finalized
+**   simply by overwriting the first journal-header with zeroes, as the
+**   master journal pointer could interfere with hot-journal rollback of any
+**   subsequently interrupted transaction that reuses the journal file.
+**
+**   The flag is cleared as soon as the journal file is finalized (either
+**   by PagerCommitPhaseTwo or PagerRollback). If an IO error prevents the
+**   journal file from being successfully finalized, the setMaster flag
+**   is cleared anyway (and the pager will move to ERROR state).
+**
+** doNotSpill
+**
+**   This variables control the behavior of cache-spills  (calls made by
+**   the pcache module to the pagerStress() routine to write cached data
+**   to the file-system in order to free up memory).
+**
+**   When bits SPILLFLAG_OFF or SPILLFLAG_ROLLBACK of doNotSpill are set,
+**   writing to the database from pagerStress() is disabled altogether.
+**   The SPILLFLAG_ROLLBACK case is done in a very obscure case that
+**   comes up during savepoint rollback that requires the pcache module
+**   to allocate a new page to prevent the journal file from being written
+**   while it is being traversed by code in pager_playback().  The SPILLFLAG_OFF
+**   case is a user preference.
+** 
+**   If the SPILLFLAG_NOSYNC bit is set, writing to the database from
+**   pagerStress() is permitted, but syncing the journal file is not.
+**   This flag is set by sqlite3PagerWrite() when the file-system sector-size
+**   is larger than the database page-size in order to prevent a journal sync
+**   from happening in between the journalling of two pages on the same sector. 
+**
+** subjInMemory
+**
+**   This is a boolean variable. If true, then any required sub-journal
+**   is opened as an in-memory journal file. If false, then in-memory
+**   sub-journals are only used for in-memory pager files.
+**
+**   This variable is updated by the upper layer each time a new 
+**   write-transaction is opened.
+**
+** dbSize, dbOrigSize, dbFileSize
+**
+**   Variable dbSize is set to the number of pages in the database file.
+**   It is valid in PAGER_READER and higher states (all states except for
+**   OPEN and ERROR). 
+**
+**   dbSize is set based on the size of the database file, which may be 
+**   larger than the size of the database (the value stored at offset
+**   28 of the database header by the btree). If the size of the file
+**   is not an integer multiple of the page-size, the value stored in
+**   dbSize is rounded down (i.e. a 5KB file with 2K page-size has dbSize==2).
+**   Except, any file that is greater than 0 bytes in size is considered
+**   to have at least one page. (i.e. a 1KB file with 2K page-size leads
+**   to dbSize==1).
+**
+**   During a write-transaction, if pages with page-numbers greater than
+**   dbSize are modified in the cache, dbSize is updated accordingly.
+**   Similarly, if the database is truncated using PagerTruncateImage(), 
+**   dbSize is updated.
+**
+**   Variables dbOrigSize and dbFileSize are valid in states 
+**   PAGER_WRITER_LOCKED and higher. dbOrigSize is a copy of the dbSize
+**   variable at the start of the transaction. It is used during rollback,
+**   and to determine whether or not pages need to be journalled before
+**   being modified.
+**
+**   Throughout a write-transaction, dbFileSize contains the size of
+**   the file on disk in pages. It is set to a copy of dbSize when the
+**   write-transaction is first opened, and updated when VFS calls are made
+**   to write or truncate the database file on disk. 
+**
+**   The only reason the dbFileSize variable is required is to suppress 
+**   unnecessary calls to xTruncate() after committing a transaction. If, 
+**   when a transaction is committed, the dbFileSize variable indicates 
+**   that the database file is larger than the database image (Pager.dbSize), 
+**   pager_truncate() is called. The pager_truncate() call uses xFilesize()
+**   to measure the database file on disk, and then truncates it if required.
+**   dbFileSize is not used when rolling back a transaction. In this case
+**   pager_truncate() is called unconditionally (which means there may be
+**   a call to xFilesize() that is not strictly required). In either case,
+**   pager_truncate() may cause the file to become smaller or larger.
+**
+** dbHintSize
+**
+**   The dbHintSize variable is used to limit the number of calls made to
+**   the VFS xFileControl(FCNTL_SIZE_HINT) method. 
+**
+**   dbHintSize is set to a copy of the dbSize variable when a
+**   write-transaction is opened (at the same time as dbFileSize and
+**   dbOrigSize). If the xFileControl(FCNTL_SIZE_HINT) method is called,
+**   dbHintSize is increased to the number of pages that correspond to the
+**   size-hint passed to the method call. See pager_write_pagelist() for 
+**   details.
+**
+** errCode
+**
+**   The Pager.errCode variable is only ever used in PAGER_ERROR state. It
+**   is set to zero in all other states. In PAGER_ERROR state, Pager.errCode 
+**   is always set to SQLITE_FULL, SQLITE_IOERR or one of the SQLITE_IOERR_XXX 
+**   sub-codes.
+*/
+struct Pager {
+  sqlite3_vfs *pVfs;          /* OS functions to use for IO */
+  u8 exclusiveMode;           /* Boolean. True if locking_mode==EXCLUSIVE */
+  u8 journalMode;             /* One of the PAGER_JOURNALMODE_* values */
+  u8 useJournal;              /* Use a rollback journal on this file */
+  u8 noSync;                  /* Do not sync the journal if true */
+  u8 fullSync;                /* Do extra syncs of the journal for robustness */
+  u8 extraSync;               /* sync directory after journal delete */
+  u8 ckptSyncFlags;           /* SYNC_NORMAL or SYNC_FULL for checkpoint */
+  u8 walSyncFlags;            /* SYNC_NORMAL or SYNC_FULL for wal writes */
+  u8 syncFlags;               /* SYNC_NORMAL or SYNC_FULL otherwise */
+  u8 tempFile;                /* zFilename is a temporary or immutable file */
+  u8 noLock;                  /* Do not lock (except in WAL mode) */
+  u8 readOnly;                /* True for a read-only database */
+  u8 memDb;                   /* True to inhibit all file I/O */
+
+  /**************************************************************************
+  ** The following block contains those class members that change during
+  ** routine operation.  Class members not in this block are either fixed
+  ** when the pager is first created or else only change when there is a
+  ** significant mode change (such as changing the page_size, locking_mode,
+  ** or the journal_mode).  From another view, these class members describe
+  ** the "state" of the pager, while other class members describe the
+  ** "configuration" of the pager.
+  */
+  u8 eState;                  /* Pager state (OPEN, READER, WRITER_LOCKED..) */
+  u8 eLock;                   /* Current lock held on database file */
+  u8 changeCountDone;         /* Set after incrementing the change-counter */
+  u8 setMaster;               /* True if a m-j name has been written to jrnl */
+  u8 doNotSpill;              /* Do not spill the cache when non-zero */
+  u8 subjInMemory;            /* True to use in-memory sub-journals */
+  u8 bUseFetch;               /* True to use xFetch() */
+  u8 hasHeldSharedLock;       /* True if a shared lock has ever been held */
+  Pgno dbSize;                /* Number of pages in the database */
+  Pgno dbOrigSize;            /* dbSize before the current transaction */
+  Pgno dbFileSize;            /* Number of pages in the database file */
+  Pgno dbHintSize;            /* Value passed to FCNTL_SIZE_HINT call */
+  int errCode;                /* One of several kinds of errors */
+  int nRec;                   /* Pages journalled since last j-header written */
+  u32 cksumInit;              /* Quasi-random value added to every checksum */
+  u32 nSubRec;                /* Number of records written to sub-journal */
+  Bitvec *pInJournal;         /* One bit for each page in the database file */
+  sqlite3_file *fd;           /* File descriptor for database */
+  sqlite3_file *jfd;          /* File descriptor for main journal */
+  sqlite3_file *sjfd;         /* File descriptor for sub-journal */
+  i64 journalOff;             /* Current write offset in the journal file */
+  i64 journalHdr;             /* Byte offset to previous journal header */
+  sqlite3_backup *pBackup;    /* Pointer to list of ongoing backup processes */
+  PagerSavepoint *aSavepoint; /* Array of active savepoints */
+  int nSavepoint;             /* Number of elements in aSavepoint[] */
+  u32 iDataVersion;           /* Changes whenever database content changes */
+  char dbFileVers[16];        /* Changes whenever database file changes */
+
+  int nMmapOut;               /* Number of mmap pages currently outstanding */
+  sqlite3_int64 szMmap;       /* Desired maximum mmap size */
+  PgHdr *pMmapFreelist;       /* List of free mmap page headers (pDirty) */
+  /*
+  ** End of the routinely-changing class members
+  ***************************************************************************/
+
+  u16 nExtra;                 /* Add this many bytes to each in-memory page */
+  i16 nReserve;               /* Number of unused bytes at end of each page */
+  u32 vfsFlags;               /* Flags for sqlite3_vfs.xOpen() */
+  u32 sectorSize;             /* Assumed sector size during rollback */
+  int pageSize;               /* Number of bytes in a page */
+  Pgno mxPgno;                /* Maximum allowed size of the database */
+  i64 journalSizeLimit;       /* Size limit for persistent journal files */
+  char *zFilename;            /* Name of the database file */
+  char *zJournal;             /* Name of the journal file */
+  int (*xBusyHandler)(void*); /* Function to call when busy */
+  void *pBusyHandlerArg;      /* Context argument for xBusyHandler */
+  int aStat[3];               /* Total cache hits, misses and writes */
+#ifdef SQLITE_TEST
+  int nRead;                  /* Database pages read */
+#endif
+  void (*xReiniter)(DbPage*); /* Call this routine when reloading pages */
+#ifdef SQLITE_HAS_CODEC
+  void *(*xCodec)(void*,void*,Pgno,int); /* Routine for en/decoding data */
+  void (*xCodecSizeChng)(void*,int,int); /* Notify of page size changes */
+  void (*xCodecFree)(void*);             /* Destructor for the codec */
+  void *pCodec;               /* First argument to xCodec... methods */
+#endif
+  char *pTmpSpace;            /* Pager.pageSize bytes of space for tmp use */
+  PCache *pPCache;            /* Pointer to page cache object */
+#ifndef SQLITE_OMIT_WAL
+  Wal *pWal;                  /* Write-ahead log used by "journal_mode=wal" */
+  char *zWal;                 /* File name for write-ahead log */
+#endif
+};
+
+/*
+** Indexes for use with Pager.aStat[]. The Pager.aStat[] array contains
+** the values accessed by passing SQLITE_DBSTATUS_CACHE_HIT, CACHE_MISS 
+** or CACHE_WRITE to sqlite3_db_status().
+*/
+#define PAGER_STAT_HIT   0
+#define PAGER_STAT_MISS  1
+#define PAGER_STAT_WRITE 2
+
+/*
+** The following global variables hold counters used for
+** testing purposes only.  These variables do not exist in
+** a non-testing build.  These variables are not thread-safe.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_pager_readdb_count = 0;    /* Number of full pages read from DB */
+SQLITE_API int sqlite3_pager_writedb_count = 0;   /* Number of full pages written to DB */
+SQLITE_API int sqlite3_pager_writej_count = 0;    /* Number of pages written to journal */
+# define PAGER_INCR(v)  v++
+#else
+# define PAGER_INCR(v)
+#endif
+
+
+
+/*
+** Journal files begin with the following magic string.  The data
+** was obtained from /dev/random.  It is used only as a sanity check.
+**
+** Since version 2.8.0, the journal format contains additional sanity
+** checking information.  If the power fails while the journal is being
+** written, semi-random garbage data might appear in the journal
+** file after power is restored.  If an attempt is then made
+** to roll the journal back, the database could be corrupted.  The additional
+** sanity checking data is an attempt to discover the garbage in the
+** journal and ignore it.
+**
+** The sanity checking information for the new journal format consists
+** of a 32-bit checksum on each page of data.  The checksum covers both
+** the page number and the pPager->pageSize bytes of data for the page.
+** This cksum is initialized to a 32-bit random value that appears in the
+** journal file right after the header.  The random initializer is important,
+** because garbage data that appears at the end of a journal is likely
+** data that was once in other files that have now been deleted.  If the
+** garbage data came from an obsolete journal file, the checksums might
+** be correct.  But by initializing the checksum to random value which
+** is different for every journal, we minimize that risk.
+*/
+static const unsigned char aJournalMagic[] = {
+  0xd9, 0xd5, 0x05, 0xf9, 0x20, 0xa1, 0x63, 0xd7,
+};
+
+/*
+** The size of the of each page record in the journal is given by
+** the following macro.
+*/
+#define JOURNAL_PG_SZ(pPager)  ((pPager->pageSize) + 8)
+
+/*
+** The journal header size for this pager. This is usually the same 
+** size as a single disk sector. See also setSectorSize().
+*/
+#define JOURNAL_HDR_SZ(pPager) (pPager->sectorSize)
+
+/*
+** The macro MEMDB is true if we are dealing with an in-memory database.
+** We do this as a macro so that if the SQLITE_OMIT_MEMORYDB macro is set,
+** the value of MEMDB will be a constant and the compiler will optimize
+** out code that would never execute.
+*/
+#ifdef SQLITE_OMIT_MEMORYDB
+# define MEMDB 0
+#else
+# define MEMDB pPager->memDb
+#endif
+
+/*
+** The macro USEFETCH is true if we are allowed to use the xFetch and xUnfetch
+** interfaces to access the database using memory-mapped I/O.
+*/
+#if SQLITE_MAX_MMAP_SIZE>0
+# define USEFETCH(x) ((x)->bUseFetch)
+#else
+# define USEFETCH(x) 0
+#endif
+
+/*
+** The maximum legal page number is (2^31 - 1).
+*/
+#define PAGER_MAX_PGNO 2147483647
+
+/*
+** The argument to this macro is a file descriptor (type sqlite3_file*).
+** Return 0 if it is not open, or non-zero (but not 1) if it is.
+**
+** This is so that expressions can be written as:
+**
+**   if( isOpen(pPager->jfd) ){ ...
+**
+** instead of
+**
+**   if( pPager->jfd->pMethods ){ ...
+*/
+#define isOpen(pFd) ((pFd)->pMethods!=0)
+
+/*
+** Return true if this pager uses a write-ahead log instead of the usual
+** rollback journal. Otherwise false.
+*/
+#ifndef SQLITE_OMIT_WAL
+SQLITE_PRIVATE int sqlite3PagerUseWal(Pager *pPager){
+  return (pPager->pWal!=0);
+}
+# define pagerUseWal(x) sqlite3PagerUseWal(x)
+#else
+# define pagerUseWal(x) 0
+# define pagerRollbackWal(x) 0
+# define pagerWalFrames(v,w,x,y) 0
+# define pagerOpenWalIfPresent(z) SQLITE_OK
+# define pagerBeginReadTransaction(z) SQLITE_OK
+#endif
+
+#ifndef NDEBUG 
+/*
+** Usage:
+**
+**   assert( assert_pager_state(pPager) );
+**
+** This function runs many asserts to try to find inconsistencies in
+** the internal state of the Pager object.
+*/
+static int assert_pager_state(Pager *p){
+  Pager *pPager = p;
+
+  /* State must be valid. */
+  assert( p->eState==PAGER_OPEN
+       || p->eState==PAGER_READER
+       || p->eState==PAGER_WRITER_LOCKED
+       || p->eState==PAGER_WRITER_CACHEMOD
+       || p->eState==PAGER_WRITER_DBMOD
+       || p->eState==PAGER_WRITER_FINISHED
+       || p->eState==PAGER_ERROR
+  );
+
+  /* Regardless of the current state, a temp-file connection always behaves
+  ** as if it has an exclusive lock on the database file. It never updates
+  ** the change-counter field, so the changeCountDone flag is always set.
+  */
+  assert( p->tempFile==0 || p->eLock==EXCLUSIVE_LOCK );
+  assert( p->tempFile==0 || pPager->changeCountDone );
+
+  /* If the useJournal flag is clear, the journal-mode must be "OFF". 
+  ** And if the journal-mode is "OFF", the journal file must not be open.
+  */
+  assert( p->journalMode==PAGER_JOURNALMODE_OFF || p->useJournal );
+  assert( p->journalMode!=PAGER_JOURNALMODE_OFF || !isOpen(p->jfd) );
+
+  /* Check that MEMDB implies noSync. And an in-memory journal. Since 
+  ** this means an in-memory pager performs no IO at all, it cannot encounter 
+  ** either SQLITE_IOERR or SQLITE_FULL during rollback or while finalizing 
+  ** a journal file. (although the in-memory journal implementation may 
+  ** return SQLITE_IOERR_NOMEM while the journal file is being written). It 
+  ** is therefore not possible for an in-memory pager to enter the ERROR 
+  ** state.
+  */
+  if( MEMDB ){
+    assert( !isOpen(p->fd) );
+    assert( p->noSync );
+    assert( p->journalMode==PAGER_JOURNALMODE_OFF 
+         || p->journalMode==PAGER_JOURNALMODE_MEMORY 
+    );
+    assert( p->eState!=PAGER_ERROR && p->eState!=PAGER_OPEN );
+    assert( pagerUseWal(p)==0 );
+  }
+
+  /* If changeCountDone is set, a RESERVED lock or greater must be held
+  ** on the file.
+  */
+  assert( pPager->changeCountDone==0 || pPager->eLock>=RESERVED_LOCK );
+  assert( p->eLock!=PENDING_LOCK );
+
+  switch( p->eState ){
+    case PAGER_OPEN:
+      assert( !MEMDB );
+      assert( pPager->errCode==SQLITE_OK );
+      assert( sqlite3PcacheRefCount(pPager->pPCache)==0 || pPager->tempFile );
+      break;
+
+    case PAGER_READER:
+      assert( pPager->errCode==SQLITE_OK );
+      assert( p->eLock!=UNKNOWN_LOCK );
+      assert( p->eLock>=SHARED_LOCK );
+      break;
+
+    case PAGER_WRITER_LOCKED:
+      assert( p->eLock!=UNKNOWN_LOCK );
+      assert( pPager->errCode==SQLITE_OK );
+      if( !pagerUseWal(pPager) ){
+        assert( p->eLock>=RESERVED_LOCK );
+      }
+      assert( pPager->dbSize==pPager->dbOrigSize );
+      assert( pPager->dbOrigSize==pPager->dbFileSize );
+      assert( pPager->dbOrigSize==pPager->dbHintSize );
+      assert( pPager->setMaster==0 );
+      break;
+
+    case PAGER_WRITER_CACHEMOD:
+      assert( p->eLock!=UNKNOWN_LOCK );
+      assert( pPager->errCode==SQLITE_OK );
+      if( !pagerUseWal(pPager) ){
+        /* It is possible that if journal_mode=wal here that neither the
+        ** journal file nor the WAL file are open. This happens during
+        ** a rollback transaction that switches from journal_mode=off
+        ** to journal_mode=wal.
+        */
+        assert( p->eLock>=RESERVED_LOCK );
+        assert( isOpen(p->jfd) 
+             || p->journalMode==PAGER_JOURNALMODE_OFF 
+             || p->journalMode==PAGER_JOURNALMODE_WAL 
+        );
+      }
+      assert( pPager->dbOrigSize==pPager->dbFileSize );
+      assert( pPager->dbOrigSize==pPager->dbHintSize );
+      break;
+
+    case PAGER_WRITER_DBMOD:
+      assert( p->eLock==EXCLUSIVE_LOCK );
+      assert( pPager->errCode==SQLITE_OK );
+      assert( !pagerUseWal(pPager) );
+      assert( p->eLock>=EXCLUSIVE_LOCK );
+      assert( isOpen(p->jfd) 
+           || p->journalMode==PAGER_JOURNALMODE_OFF 
+           || p->journalMode==PAGER_JOURNALMODE_WAL 
+      );
+      assert( pPager->dbOrigSize<=pPager->dbHintSize );
+      break;
+
+    case PAGER_WRITER_FINISHED:
+      assert( p->eLock==EXCLUSIVE_LOCK );
+      assert( pPager->errCode==SQLITE_OK );
+      assert( !pagerUseWal(pPager) );
+      assert( isOpen(p->jfd) 
+           || p->journalMode==PAGER_JOURNALMODE_OFF 
+           || p->journalMode==PAGER_JOURNALMODE_WAL 
+      );
+      break;
+
+    case PAGER_ERROR:
+      /* There must be at least one outstanding reference to the pager if
+      ** in ERROR state. Otherwise the pager should have already dropped
+      ** back to OPEN state.
+      */
+      assert( pPager->errCode!=SQLITE_OK );
+      assert( sqlite3PcacheRefCount(pPager->pPCache)>0 || pPager->tempFile );
+      break;
+  }
+
+  return 1;
+}
+#endif /* ifndef NDEBUG */
+
+#ifdef SQLITE_DEBUG 
+/*
+** Return a pointer to a human readable string in a static buffer
+** containing the state of the Pager object passed as an argument. This
+** is intended to be used within debuggers. For example, as an alternative
+** to "print *pPager" in gdb:
+**
+** (gdb) printf "%s", print_pager_state(pPager)
+*/
+static char *print_pager_state(Pager *p){
+  static char zRet[1024];
+
+  sqlite3_snprintf(1024, zRet,
+      "Filename:      %s\n"
+      "State:         %s errCode=%d\n"
+      "Lock:          %s\n"
+      "Locking mode:  locking_mode=%s\n"
+      "Journal mode:  journal_mode=%s\n"
+      "Backing store: tempFile=%d memDb=%d useJournal=%d\n"
+      "Journal:       journalOff=%lld journalHdr=%lld\n"
+      "Size:          dbsize=%d dbOrigSize=%d dbFileSize=%d\n"
+      , p->zFilename
+      , p->eState==PAGER_OPEN            ? "OPEN" :
+        p->eState==PAGER_READER          ? "READER" :
+        p->eState==PAGER_WRITER_LOCKED   ? "WRITER_LOCKED" :
+        p->eState==PAGER_WRITER_CACHEMOD ? "WRITER_CACHEMOD" :
+        p->eState==PAGER_WRITER_DBMOD    ? "WRITER_DBMOD" :
+        p->eState==PAGER_WRITER_FINISHED ? "WRITER_FINISHED" :
+        p->eState==PAGER_ERROR           ? "ERROR" : "?error?"
+      , (int)p->errCode
+      , p->eLock==NO_LOCK         ? "NO_LOCK" :
+        p->eLock==RESERVED_LOCK   ? "RESERVED" :
+        p->eLock==EXCLUSIVE_LOCK  ? "EXCLUSIVE" :
+        p->eLock==SHARED_LOCK     ? "SHARED" :
+        p->eLock==UNKNOWN_LOCK    ? "UNKNOWN" : "?error?"
+      , p->exclusiveMode ? "exclusive" : "normal"
+      , p->journalMode==PAGER_JOURNALMODE_MEMORY   ? "memory" :
+        p->journalMode==PAGER_JOURNALMODE_OFF      ? "off" :
+        p->journalMode==PAGER_JOURNALMODE_DELETE   ? "delete" :
+        p->journalMode==PAGER_JOURNALMODE_PERSIST  ? "persist" :
+        p->journalMode==PAGER_JOURNALMODE_TRUNCATE ? "truncate" :
+        p->journalMode==PAGER_JOURNALMODE_WAL      ? "wal" : "?error?"
+      , (int)p->tempFile, (int)p->memDb, (int)p->useJournal
+      , p->journalOff, p->journalHdr
+      , (int)p->dbSize, (int)p->dbOrigSize, (int)p->dbFileSize
+  );
+
+  return zRet;
+}
+#endif
+
+/*
+** Return true if it is necessary to write page *pPg into the sub-journal.
+** A page needs to be written into the sub-journal if there exists one
+** or more open savepoints for which:
+**
+**   * The page-number is less than or equal to PagerSavepoint.nOrig, and
+**   * The bit corresponding to the page-number is not set in
+**     PagerSavepoint.pInSavepoint.
+*/
+static int subjRequiresPage(PgHdr *pPg){
+  Pager *pPager = pPg->pPager;
+  PagerSavepoint *p;
+  Pgno pgno = pPg->pgno;
+  int i;
+  for(i=0; i<pPager->nSavepoint; i++){
+    p = &pPager->aSavepoint[i];
+    if( p->nOrig>=pgno && 0==sqlite3BitvecTestNotNull(p->pInSavepoint, pgno) ){
+      return 1;
+    }
+  }
+  return 0;
+}
+
+#ifdef SQLITE_DEBUG
+/*
+** Return true if the page is already in the journal file.
+*/
+static int pageInJournal(Pager *pPager, PgHdr *pPg){
+  return sqlite3BitvecTest(pPager->pInJournal, pPg->pgno);
+}
+#endif
+
+/*
+** Read a 32-bit integer from the given file descriptor.  Store the integer
+** that is read in *pRes.  Return SQLITE_OK if everything worked, or an
+** error code is something goes wrong.
+**
+** All values are stored on disk as big-endian.
+*/
+static int read32bits(sqlite3_file *fd, i64 offset, u32 *pRes){
+  unsigned char ac[4];
+  int rc = sqlite3OsRead(fd, ac, sizeof(ac), offset);
+  if( rc==SQLITE_OK ){
+    *pRes = sqlite3Get4byte(ac);
+  }
+  return rc;
+}
+
+/*
+** Write a 32-bit integer into a string buffer in big-endian byte order.
+*/
+#define put32bits(A,B)  sqlite3Put4byte((u8*)A,B)
+
+
+/*
+** Write a 32-bit integer into the given file descriptor.  Return SQLITE_OK
+** on success or an error code is something goes wrong.
+*/
+static int write32bits(sqlite3_file *fd, i64 offset, u32 val){
+  char ac[4];
+  put32bits(ac, val);
+  return sqlite3OsWrite(fd, ac, 4, offset);
+}
+
+/*
+** Unlock the database file to level eLock, which must be either NO_LOCK
+** or SHARED_LOCK. Regardless of whether or not the call to xUnlock()
+** succeeds, set the Pager.eLock variable to match the (attempted) new lock.
+**
+** Except, if Pager.eLock is set to UNKNOWN_LOCK when this function is
+** called, do not modify it. See the comment above the #define of 
+** UNKNOWN_LOCK for an explanation of this.
+*/
+static int pagerUnlockDb(Pager *pPager, int eLock){
+  int rc = SQLITE_OK;
+
+  assert( !pPager->exclusiveMode || pPager->eLock==eLock );
+  assert( eLock==NO_LOCK || eLock==SHARED_LOCK );
+  assert( eLock!=NO_LOCK || pagerUseWal(pPager)==0 );
+  if( isOpen(pPager->fd) ){
+    assert( pPager->eLock>=eLock );
+    rc = pPager->noLock ? SQLITE_OK : sqlite3OsUnlock(pPager->fd, eLock);
+    if( pPager->eLock!=UNKNOWN_LOCK ){
+      pPager->eLock = (u8)eLock;
+    }
+    IOTRACE(("UNLOCK %p %d\n", pPager, eLock))
+  }
+  return rc;
+}
+
+/*
+** Lock the database file to level eLock, which must be either SHARED_LOCK,
+** RESERVED_LOCK or EXCLUSIVE_LOCK. If the caller is successful, set the
+** Pager.eLock variable to the new locking state. 
+**
+** Except, if Pager.eLock is set to UNKNOWN_LOCK when this function is 
+** called, do not modify it unless the new locking state is EXCLUSIVE_LOCK. 
+** See the comment above the #define of UNKNOWN_LOCK for an explanation 
+** of this.
+*/
+static int pagerLockDb(Pager *pPager, int eLock){
+  int rc = SQLITE_OK;
+
+  assert( eLock==SHARED_LOCK || eLock==RESERVED_LOCK || eLock==EXCLUSIVE_LOCK );
+  if( pPager->eLock<eLock || pPager->eLock==UNKNOWN_LOCK ){
+    rc = pPager->noLock ? SQLITE_OK : sqlite3OsLock(pPager->fd, eLock);
+    if( rc==SQLITE_OK && (pPager->eLock!=UNKNOWN_LOCK||eLock==EXCLUSIVE_LOCK) ){
+      pPager->eLock = (u8)eLock;
+      IOTRACE(("LOCK %p %d\n", pPager, eLock))
+    }
+  }
+  return rc;
+}
+
+/*
+** This function determines whether or not the atomic-write optimization
+** can be used with this pager. The optimization can be used if:
+**
+**  (a) the value returned by OsDeviceCharacteristics() indicates that
+**      a database page may be written atomically, and
+**  (b) the value returned by OsSectorSize() is less than or equal
+**      to the page size.
+**
+** The optimization is also always enabled for temporary files. It is
+** an error to call this function if pPager is opened on an in-memory
+** database.
+**
+** If the optimization cannot be used, 0 is returned. If it can be used,
+** then the value returned is the size of the journal file when it
+** contains rollback data for exactly one page.
+*/
+#ifdef SQLITE_ENABLE_ATOMIC_WRITE
+static int jrnlBufferSize(Pager *pPager){
+  assert( !MEMDB );
+  if( !pPager->tempFile ){
+    int dc;                           /* Device characteristics */
+    int nSector;                      /* Sector size */
+    int szPage;                       /* Page size */
+
+    assert( isOpen(pPager->fd) );
+    dc = sqlite3OsDeviceCharacteristics(pPager->fd);
+    nSector = pPager->sectorSize;
+    szPage = pPager->pageSize;
+
+    assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
+    assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));
+    if( 0==(dc&(SQLITE_IOCAP_ATOMIC|(szPage>>8)) || nSector>szPage) ){
+      return 0;
+    }
+  }
+
+  return JOURNAL_HDR_SZ(pPager) + JOURNAL_PG_SZ(pPager);
+}
+#else
+# define jrnlBufferSize(x) 0
+#endif
+
+/*
+** If SQLITE_CHECK_PAGES is defined then we do some sanity checking
+** on the cache using a hash function.  This is used for testing
+** and debugging only.
+*/
+#ifdef SQLITE_CHECK_PAGES
+/*
+** Return a 32-bit hash of the page data for pPage.
+*/
+static u32 pager_datahash(int nByte, unsigned char *pData){
+  u32 hash = 0;
+  int i;
+  for(i=0; i<nByte; i++){
+    hash = (hash*1039) + pData[i];
+  }
+  return hash;
+}
+static u32 pager_pagehash(PgHdr *pPage){
+  return pager_datahash(pPage->pPager->pageSize, (unsigned char *)pPage->pData);
+}
+static void pager_set_pagehash(PgHdr *pPage){
+  pPage->pageHash = pager_pagehash(pPage);
+}
+
+/*
+** The CHECK_PAGE macro takes a PgHdr* as an argument. If SQLITE_CHECK_PAGES
+** is defined, and NDEBUG is not defined, an assert() statement checks
+** that the page is either dirty or still matches the calculated page-hash.
+*/
+#define CHECK_PAGE(x) checkPage(x)
+static void checkPage(PgHdr *pPg){
+  Pager *pPager = pPg->pPager;
+  assert( pPager->eState!=PAGER_ERROR );
+  assert( (pPg->flags&PGHDR_DIRTY) || pPg->pageHash==pager_pagehash(pPg) );
+}
+
+#else
+#define pager_datahash(X,Y)  0
+#define pager_pagehash(X)  0
+#define pager_set_pagehash(X)
+#define CHECK_PAGE(x)
+#endif  /* SQLITE_CHECK_PAGES */
+
+/*
+** When this is called the journal file for pager pPager must be open.
+** This function attempts to read a master journal file name from the 
+** end of the file and, if successful, copies it into memory supplied 
+** by the caller. See comments above writeMasterJournal() for the format
+** used to store a master journal file name at the end of a journal file.
+**
+** zMaster must point to a buffer of at least nMaster bytes allocated by
+** the caller. This should be sqlite3_vfs.mxPathname+1 (to ensure there is
+** enough space to write the master journal name). If the master journal
+** name in the journal is longer than nMaster bytes (including a
+** nul-terminator), then this is handled as if no master journal name
+** were present in the journal.
+**
+** If a master journal file name is present at the end of the journal
+** file, then it is copied into the buffer pointed to by zMaster. A
+** nul-terminator byte is appended to the buffer following the master
+** journal file name.
+**
+** If it is determined that no master journal file name is present 
+** zMaster[0] is set to 0 and SQLITE_OK returned.
+**
+** If an error occurs while reading from the journal file, an SQLite
+** error code is returned.
+*/
+static int readMasterJournal(sqlite3_file *pJrnl, char *zMaster, u32 nMaster){
+  int rc;                    /* Return code */
+  u32 len;                   /* Length in bytes of master journal name */
+  i64 szJ;                   /* Total size in bytes of journal file pJrnl */
+  u32 cksum;                 /* MJ checksum value read from journal */
+  u32 u;                     /* Unsigned loop counter */
+  unsigned char aMagic[8];   /* A buffer to hold the magic header */
+  zMaster[0] = '\0';
+
+  if( SQLITE_OK!=(rc = sqlite3OsFileSize(pJrnl, &szJ))
+   || szJ<16
+   || SQLITE_OK!=(rc = read32bits(pJrnl, szJ-16, &len))
+   || len>=nMaster 
+   || len==0 
+   || SQLITE_OK!=(rc = read32bits(pJrnl, szJ-12, &cksum))
+   || SQLITE_OK!=(rc = sqlite3OsRead(pJrnl, aMagic, 8, szJ-8))
+   || memcmp(aMagic, aJournalMagic, 8)
+   || SQLITE_OK!=(rc = sqlite3OsRead(pJrnl, zMaster, len, szJ-16-len))
+  ){
+    return rc;
+  }
+
+  /* See if the checksum matches the master journal name */
+  for(u=0; u<len; u++){
+    cksum -= zMaster[u];
+  }
+  if( cksum ){
+    /* If the checksum doesn't add up, then one or more of the disk sectors
+    ** containing the master journal filename is corrupted. This means
+    ** definitely roll back, so just return SQLITE_OK and report a (nul)
+    ** master-journal filename.
+    */
+    len = 0;
+  }
+  zMaster[len] = '\0';
+   
+  return SQLITE_OK;
+}
+
+/*
+** Return the offset of the sector boundary at or immediately 
+** following the value in pPager->journalOff, assuming a sector 
+** size of pPager->sectorSize bytes.
+**
+** i.e for a sector size of 512:
+**
+**   Pager.journalOff          Return value
+**   ---------------------------------------
+**   0                         0
+**   512                       512
+**   100                       512
+**   2000                      2048
+** 
+*/
+static i64 journalHdrOffset(Pager *pPager){
+  i64 offset = 0;
+  i64 c = pPager->journalOff;
+  if( c ){
+    offset = ((c-1)/JOURNAL_HDR_SZ(pPager) + 1) * JOURNAL_HDR_SZ(pPager);
+  }
+  assert( offset%JOURNAL_HDR_SZ(pPager)==0 );
+  assert( offset>=c );
+  assert( (offset-c)<JOURNAL_HDR_SZ(pPager) );
+  return offset;
+}
+
+/*
+** The journal file must be open when this function is called.
+**
+** This function is a no-op if the journal file has not been written to
+** within the current transaction (i.e. if Pager.journalOff==0).
+**
+** If doTruncate is non-zero or the Pager.journalSizeLimit variable is
+** set to 0, then truncate the journal file to zero bytes in size. Otherwise,
+** zero the 28-byte header at the start of the journal file. In either case, 
+** if the pager is not in no-sync mode, sync the journal file immediately 
+** after writing or truncating it.
+**
+** If Pager.journalSizeLimit is set to a positive, non-zero value, and
+** following the truncation or zeroing described above the size of the 
+** journal file in bytes is larger than this value, then truncate the
+** journal file to Pager.journalSizeLimit bytes. The journal file does
+** not need to be synced following this operation.
+**
+** If an IO error occurs, abandon processing and return the IO error code.
+** Otherwise, return SQLITE_OK.
+*/
+static int zeroJournalHdr(Pager *pPager, int doTruncate){
+  int rc = SQLITE_OK;                               /* Return code */
+  assert( isOpen(pPager->jfd) );
+  assert( !sqlite3JournalIsInMemory(pPager->jfd) );
+  if( pPager->journalOff ){
+    const i64 iLimit = pPager->journalSizeLimit;    /* Local cache of jsl */
+
+    IOTRACE(("JZEROHDR %p\n", pPager))
+    if( doTruncate || iLimit==0 ){
+      rc = sqlite3OsTruncate(pPager->jfd, 0);
+    }else{
+      static const char zeroHdr[28] = {0};
+      rc = sqlite3OsWrite(pPager->jfd, zeroHdr, sizeof(zeroHdr), 0);
+    }
+    if( rc==SQLITE_OK && !pPager->noSync ){
+      rc = sqlite3OsSync(pPager->jfd, SQLITE_SYNC_DATAONLY|pPager->syncFlags);
+    }
+
+    /* At this point the transaction is committed but the write lock 
+    ** is still held on the file. If there is a size limit configured for 
+    ** the persistent journal and the journal file currently consumes more
+    ** space than that limit allows for, truncate it now. There is no need
+    ** to sync the file following this operation.
+    */
+    if( rc==SQLITE_OK && iLimit>0 ){
+      i64 sz;
+      rc = sqlite3OsFileSize(pPager->jfd, &sz);
+      if( rc==SQLITE_OK && sz>iLimit ){
+        rc = sqlite3OsTruncate(pPager->jfd, iLimit);
+      }
+    }
+  }
+  return rc;
+}
+
+/*
+** The journal file must be open when this routine is called. A journal
+** header (JOURNAL_HDR_SZ bytes) is written into the journal file at the
+** current location.
+**
+** The format for the journal header is as follows:
+** - 8 bytes: Magic identifying journal format.
+** - 4 bytes: Number of records in journal, or -1 no-sync mode is on.
+** - 4 bytes: Random number used for page hash.
+** - 4 bytes: Initial database page count.
+** - 4 bytes: Sector size used by the process that wrote this journal.
+** - 4 bytes: Database page size.
+** 
+** Followed by (JOURNAL_HDR_SZ - 28) bytes of unused space.
+*/
+static int writeJournalHdr(Pager *pPager){
+  int rc = SQLITE_OK;                 /* Return code */
+  char *zHeader = pPager->pTmpSpace;  /* Temporary space used to build header */
+  u32 nHeader = (u32)pPager->pageSize;/* Size of buffer pointed to by zHeader */
+  u32 nWrite;                         /* Bytes of header sector written */
+  int ii;                             /* Loop counter */
+
+  assert( isOpen(pPager->jfd) );      /* Journal file must be open. */
+
+  if( nHeader>JOURNAL_HDR_SZ(pPager) ){
+    nHeader = JOURNAL_HDR_SZ(pPager);
+  }
+
+  /* If there are active savepoints and any of them were created 
+  ** since the most recent journal header was written, update the 
+  ** PagerSavepoint.iHdrOffset fields now.
+  */
+  for(ii=0; ii<pPager->nSavepoint; ii++){
+    if( pPager->aSavepoint[ii].iHdrOffset==0 ){
+      pPager->aSavepoint[ii].iHdrOffset = pPager->journalOff;
+    }
+  }
+
+  pPager->journalHdr = pPager->journalOff = journalHdrOffset(pPager);
+
+  /* 
+  ** Write the nRec Field - the number of page records that follow this
+  ** journal header. Normally, zero is written to this value at this time.
+  ** After the records are added to the journal (and the journal synced, 
+  ** if in full-sync mode), the zero is overwritten with the true number
+  ** of records (see syncJournal()).
+  **
+  ** A faster alternative is to write 0xFFFFFFFF to the nRec field. When
+  ** reading the journal this value tells SQLite to assume that the
+  ** rest of the journal file contains valid page records. This assumption
+  ** is dangerous, as if a failure occurred whilst writing to the journal
+  ** file it may contain some garbage data. There are two scenarios
+  ** where this risk can be ignored:
+  **
+  **   * When the pager is in no-sync mode. Corruption can follow a
+  **     power failure in this case anyway.
+  **
+  **   * When the SQLITE_IOCAP_SAFE_APPEND flag is set. This guarantees
+  **     that garbage data is never appended to the journal file.
+  */
+  assert( isOpen(pPager->fd) || pPager->noSync );
+  if( pPager->noSync || (pPager->journalMode==PAGER_JOURNALMODE_MEMORY)
+   || (sqlite3OsDeviceCharacteristics(pPager->fd)&SQLITE_IOCAP_SAFE_APPEND) 
+  ){
+    memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic));
+    put32bits(&zHeader[sizeof(aJournalMagic)], 0xffffffff);
+  }else{
+    memset(zHeader, 0, sizeof(aJournalMagic)+4);
+  }
+
+  /* The random check-hash initializer */ 
+  sqlite3_randomness(sizeof(pPager->cksumInit), &pPager->cksumInit);
+  put32bits(&zHeader[sizeof(aJournalMagic)+4], pPager->cksumInit);
+  /* The initial database size */
+  put32bits(&zHeader[sizeof(aJournalMagic)+8], pPager->dbOrigSize);
+  /* The assumed sector size for this process */
+  put32bits(&zHeader[sizeof(aJournalMagic)+12], pPager->sectorSize);
+
+  /* The page size */
+  put32bits(&zHeader[sizeof(aJournalMagic)+16], pPager->pageSize);
+
+  /* Initializing the tail of the buffer is not necessary.  Everything
+  ** works find if the following memset() is omitted.  But initializing
+  ** the memory prevents valgrind from complaining, so we are willing to
+  ** take the performance hit.
+  */
+  memset(&zHeader[sizeof(aJournalMagic)+20], 0,
+         nHeader-(sizeof(aJournalMagic)+20));
+
+  /* In theory, it is only necessary to write the 28 bytes that the 
+  ** journal header consumes to the journal file here. Then increment the 
+  ** Pager.journalOff variable by JOURNAL_HDR_SZ so that the next 
+  ** record is written to the following sector (leaving a gap in the file
+  ** that will be implicitly filled in by the OS).
+  **
+  ** However it has been discovered that on some systems this pattern can 
+  ** be significantly slower than contiguously writing data to the file,
+  ** even if that means explicitly writing data to the block of 
+  ** (JOURNAL_HDR_SZ - 28) bytes that will not be used. So that is what
+  ** is done. 
+  **
+  ** The loop is required here in case the sector-size is larger than the 
+  ** database page size. Since the zHeader buffer is only Pager.pageSize
+  ** bytes in size, more than one call to sqlite3OsWrite() may be required
+  ** to populate the entire journal header sector.
+  */ 
+  for(nWrite=0; rc==SQLITE_OK&&nWrite<JOURNAL_HDR_SZ(pPager); nWrite+=nHeader){
+    IOTRACE(("JHDR %p %lld %d\n", pPager, pPager->journalHdr, nHeader))
+    rc = sqlite3OsWrite(pPager->jfd, zHeader, nHeader, pPager->journalOff);
+    assert( pPager->journalHdr <= pPager->journalOff );
+    pPager->journalOff += nHeader;
+  }
+
+  return rc;
+}
+
+/*
+** The journal file must be open when this is called. A journal header file
+** (JOURNAL_HDR_SZ bytes) is read from the current location in the journal
+** file. The current location in the journal file is given by
+** pPager->journalOff. See comments above function writeJournalHdr() for
+** a description of the journal header format.
+**
+** If the header is read successfully, *pNRec is set to the number of
+** page records following this header and *pDbSize is set to the size of the
+** database before the transaction began, in pages. Also, pPager->cksumInit
+** is set to the value read from the journal header. SQLITE_OK is returned
+** in this case.
+**
+** If the journal header file appears to be corrupted, SQLITE_DONE is
+** returned and *pNRec and *PDbSize are undefined.  If JOURNAL_HDR_SZ bytes
+** cannot be read from the journal file an error code is returned.
+*/
+static int readJournalHdr(
+  Pager *pPager,               /* Pager object */
+  int isHot,
+  i64 journalSize,             /* Size of the open journal file in bytes */
+  u32 *pNRec,                  /* OUT: Value read from the nRec field */
+  u32 *pDbSize                 /* OUT: Value of original database size field */
+){
+  int rc;                      /* Return code */
+  unsigned char aMagic[8];     /* A buffer to hold the magic header */
+  i64 iHdrOff;                 /* Offset of journal header being read */
+
+  assert( isOpen(pPager->jfd) );      /* Journal file must be open. */
+
+  /* Advance Pager.journalOff to the start of the next sector. If the
+  ** journal file is too small for there to be a header stored at this
+  ** point, return SQLITE_DONE.
+  */
+  pPager->journalOff = journalHdrOffset(pPager);
+  if( pPager->journalOff+JOURNAL_HDR_SZ(pPager) > journalSize ){
+    return SQLITE_DONE;
+  }
+  iHdrOff = pPager->journalOff;
+
+  /* Read in the first 8 bytes of the journal header. If they do not match
+  ** the  magic string found at the start of each journal header, return
+  ** SQLITE_DONE. If an IO error occurs, return an error code. Otherwise,
+  ** proceed.
+  */
+  if( isHot || iHdrOff!=pPager->journalHdr ){
+    rc = sqlite3OsRead(pPager->jfd, aMagic, sizeof(aMagic), iHdrOff);
+    if( rc ){
+      return rc;
+    }
+    if( memcmp(aMagic, aJournalMagic, sizeof(aMagic))!=0 ){
+      return SQLITE_DONE;
+    }
+  }
+
+  /* Read the first three 32-bit fields of the journal header: The nRec
+  ** field, the checksum-initializer and the database size at the start
+  ** of the transaction. Return an error code if anything goes wrong.
+  */
+  if( SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+8, pNRec))
+   || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+12, &pPager->cksumInit))
+   || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+16, pDbSize))
+  ){
+    return rc;
+  }
+
+  if( pPager->journalOff==0 ){
+    u32 iPageSize;               /* Page-size field of journal header */
+    u32 iSectorSize;             /* Sector-size field of journal header */
+
+    /* Read the page-size and sector-size journal header fields. */
+    if( SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+20, &iSectorSize))
+     || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+24, &iPageSize))
+    ){
+      return rc;
+    }
+
+    /* Versions of SQLite prior to 3.5.8 set the page-size field of the
+    ** journal header to zero. In this case, assume that the Pager.pageSize
+    ** variable is already set to the correct page size.
+    */
+    if( iPageSize==0 ){
+      iPageSize = pPager->pageSize;
+    }
+
+    /* Check that the values read from the page-size and sector-size fields
+    ** are within range. To be 'in range', both values need to be a power
+    ** of two greater than or equal to 512 or 32, and not greater than their 
+    ** respective compile time maximum limits.
+    */
+    if( iPageSize<512                  || iSectorSize<32
+     || iPageSize>SQLITE_MAX_PAGE_SIZE || iSectorSize>MAX_SECTOR_SIZE
+     || ((iPageSize-1)&iPageSize)!=0   || ((iSectorSize-1)&iSectorSize)!=0 
+    ){
+      /* If the either the page-size or sector-size in the journal-header is 
+      ** invalid, then the process that wrote the journal-header must have 
+      ** crashed before the header was synced. In this case stop reading 
+      ** the journal file here.
+      */
+      return SQLITE_DONE;
+    }
+
+    /* Update the page-size to match the value read from the journal. 
+    ** Use a testcase() macro to make sure that malloc failure within 
+    ** PagerSetPagesize() is tested.
+    */
+    rc = sqlite3PagerSetPagesize(pPager, &iPageSize, -1);
+    testcase( rc!=SQLITE_OK );
+
+    /* Update the assumed sector-size to match the value used by 
+    ** the process that created this journal. If this journal was
+    ** created by a process other than this one, then this routine
+    ** is being called from within pager_playback(). The local value
+    ** of Pager.sectorSize is restored at the end of that routine.
+    */
+    pPager->sectorSize = iSectorSize;
+  }
+
+  pPager->journalOff += JOURNAL_HDR_SZ(pPager);
+  return rc;
+}
+
+
+/*
+** Write the supplied master journal name into the journal file for pager
+** pPager at the current location. The master journal name must be the last
+** thing written to a journal file. If the pager is in full-sync mode, the
+** journal file descriptor is advanced to the next sector boundary before
+** anything is written. The format is:
+**
+**   + 4 bytes: PAGER_MJ_PGNO.
+**   + N bytes: Master journal filename in utf-8.
+**   + 4 bytes: N (length of master journal name in bytes, no nul-terminator).
+**   + 4 bytes: Master journal name checksum.
+**   + 8 bytes: aJournalMagic[].
+**
+** The master journal page checksum is the sum of the bytes in the master
+** journal name, where each byte is interpreted as a signed 8-bit integer.
+**
+** If zMaster is a NULL pointer (occurs for a single database transaction), 
+** this call is a no-op.
+*/
+static int writeMasterJournal(Pager *pPager, const char *zMaster){
+  int rc;                          /* Return code */
+  int nMaster;                     /* Length of string zMaster */
+  i64 iHdrOff;                     /* Offset of header in journal file */
+  i64 jrnlSize;                    /* Size of journal file on disk */
+  u32 cksum = 0;                   /* Checksum of string zMaster */
+
+  assert( pPager->setMaster==0 );
+  assert( !pagerUseWal(pPager) );
+
+  if( !zMaster 
+   || pPager->journalMode==PAGER_JOURNALMODE_MEMORY 
+   || !isOpen(pPager->jfd)
+  ){
+    return SQLITE_OK;
+  }
+  pPager->setMaster = 1;
+  assert( pPager->journalHdr <= pPager->journalOff );
+
+  /* Calculate the length in bytes and the checksum of zMaster */
+  for(nMaster=0; zMaster[nMaster]; nMaster++){
+    cksum += zMaster[nMaster];
+  }
+
+  /* If in full-sync mode, advance to the next disk sector before writing
+  ** the master journal name. This is in case the previous page written to
+  ** the journal has already been synced.
+  */
+  if( pPager->fullSync ){
+    pPager->journalOff = journalHdrOffset(pPager);
+  }
+  iHdrOff = pPager->journalOff;
+
+  /* Write the master journal data to the end of the journal file. If
+  ** an error occurs, return the error code to the caller.
+  */
+  if( (0 != (rc = write32bits(pPager->jfd, iHdrOff, PAGER_MJ_PGNO(pPager))))
+   || (0 != (rc = sqlite3OsWrite(pPager->jfd, zMaster, nMaster, iHdrOff+4)))
+   || (0 != (rc = write32bits(pPager->jfd, iHdrOff+4+nMaster, nMaster)))
+   || (0 != (rc = write32bits(pPager->jfd, iHdrOff+4+nMaster+4, cksum)))
+   || (0 != (rc = sqlite3OsWrite(pPager->jfd, aJournalMagic, 8,
+                                 iHdrOff+4+nMaster+8)))
+  ){
+    return rc;
+  }
+  pPager->journalOff += (nMaster+20);
+
+  /* If the pager is in peristent-journal mode, then the physical 
+  ** journal-file may extend past the end of the master-journal name
+  ** and 8 bytes of magic data just written to the file. This is 
+  ** dangerous because the code to rollback a hot-journal file
+  ** will not be able to find the master-journal name to determine 
+  ** whether or not the journal is hot. 
+  **
+  ** Easiest thing to do in this scenario is to truncate the journal 
+  ** file to the required size.
+  */ 
+  if( SQLITE_OK==(rc = sqlite3OsFileSize(pPager->jfd, &jrnlSize))
+   && jrnlSize>pPager->journalOff
+  ){
+    rc = sqlite3OsTruncate(pPager->jfd, pPager->journalOff);
+  }
+  return rc;
+}
+
+/*
+** Discard the entire contents of the in-memory page-cache.
+*/
+static void pager_reset(Pager *pPager){
+  pPager->iDataVersion++;
+  sqlite3BackupRestart(pPager->pBackup);
+  sqlite3PcacheClear(pPager->pPCache);
+}
+
+/*
+** Return the pPager->iDataVersion value
+*/
+SQLITE_PRIVATE u32 sqlite3PagerDataVersion(Pager *pPager){
+  assert( pPager->eState>PAGER_OPEN );
+  return pPager->iDataVersion;
+}
+
+/*
+** Free all structures in the Pager.aSavepoint[] array and set both
+** Pager.aSavepoint and Pager.nSavepoint to zero. Close the sub-journal
+** if it is open and the pager is not in exclusive mode.
+*/
+static void releaseAllSavepoints(Pager *pPager){
+  int ii;               /* Iterator for looping through Pager.aSavepoint */
+  for(ii=0; ii<pPager->nSavepoint; ii++){
+    sqlite3BitvecDestroy(pPager->aSavepoint[ii].pInSavepoint);
+  }
+  if( !pPager->exclusiveMode || sqlite3JournalIsInMemory(pPager->sjfd) ){
+    sqlite3OsClose(pPager->sjfd);
+  }
+  sqlite3_free(pPager->aSavepoint);
+  pPager->aSavepoint = 0;
+  pPager->nSavepoint = 0;
+  pPager->nSubRec = 0;
+}
+
+/*
+** Set the bit number pgno in the PagerSavepoint.pInSavepoint 
+** bitvecs of all open savepoints. Return SQLITE_OK if successful
+** or SQLITE_NOMEM if a malloc failure occurs.
+*/
+static int addToSavepointBitvecs(Pager *pPager, Pgno pgno){
+  int ii;                   /* Loop counter */
+  int rc = SQLITE_OK;       /* Result code */
+
+  for(ii=0; ii<pPager->nSavepoint; ii++){
+    PagerSavepoint *p = &pPager->aSavepoint[ii];
+    if( pgno<=p->nOrig ){
+      rc |= sqlite3BitvecSet(p->pInSavepoint, pgno);
+      testcase( rc==SQLITE_NOMEM );
+      assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
+    }
+  }
+  return rc;
+}
+
+/*
+** This function is a no-op if the pager is in exclusive mode and not
+** in the ERROR state. Otherwise, it switches the pager to PAGER_OPEN
+** state.
+**
+** If the pager is not in exclusive-access mode, the database file is
+** completely unlocked. If the file is unlocked and the file-system does
+** not exhibit the UNDELETABLE_WHEN_OPEN property, the journal file is
+** closed (if it is open).
+**
+** If the pager is in ERROR state when this function is called, the 
+** contents of the pager cache are discarded before switching back to 
+** the OPEN state. Regardless of whether the pager is in exclusive-mode
+** or not, any journal file left in the file-system will be treated
+** as a hot-journal and rolled back the next time a read-transaction
+** is opened (by this or by any other connection).
+*/
+static void pager_unlock(Pager *pPager){
+
+  assert( pPager->eState==PAGER_READER 
+       || pPager->eState==PAGER_OPEN 
+       || pPager->eState==PAGER_ERROR 
+  );
+
+  sqlite3BitvecDestroy(pPager->pInJournal);
+  pPager->pInJournal = 0;
+  releaseAllSavepoints(pPager);
+
+  if( pagerUseWal(pPager) ){
+    assert( !isOpen(pPager->jfd) );
+    sqlite3WalEndReadTransaction(pPager->pWal);
+    pPager->eState = PAGER_OPEN;
+  }else if( !pPager->exclusiveMode ){
+    int rc;                       /* Error code returned by pagerUnlockDb() */
+    int iDc = isOpen(pPager->fd)?sqlite3OsDeviceCharacteristics(pPager->fd):0;
+
+    /* If the operating system support deletion of open files, then
+    ** close the journal file when dropping the database lock.  Otherwise
+    ** another connection with journal_mode=delete might delete the file
+    ** out from under us.
+    */
+    assert( (PAGER_JOURNALMODE_MEMORY   & 5)!=1 );
+    assert( (PAGER_JOURNALMODE_OFF      & 5)!=1 );
+    assert( (PAGER_JOURNALMODE_WAL      & 5)!=1 );
+    assert( (PAGER_JOURNALMODE_DELETE   & 5)!=1 );
+    assert( (PAGER_JOURNALMODE_TRUNCATE & 5)==1 );
+    assert( (PAGER_JOURNALMODE_PERSIST  & 5)==1 );
+    if( 0==(iDc & SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN)
+     || 1!=(pPager->journalMode & 5)
+    ){
+      sqlite3OsClose(pPager->jfd);
+    }
+
+    /* If the pager is in the ERROR state and the call to unlock the database
+    ** file fails, set the current lock to UNKNOWN_LOCK. See the comment
+    ** above the #define for UNKNOWN_LOCK for an explanation of why this
+    ** is necessary.
+    */
+    rc = pagerUnlockDb(pPager, NO_LOCK);
+    if( rc!=SQLITE_OK && pPager->eState==PAGER_ERROR ){
+      pPager->eLock = UNKNOWN_LOCK;
+    }
+
+    /* The pager state may be changed from PAGER_ERROR to PAGER_OPEN here
+    ** without clearing the error code. This is intentional - the error
+    ** code is cleared and the cache reset in the block below.
+    */
+    assert( pPager->errCode || pPager->eState!=PAGER_ERROR );
+    pPager->changeCountDone = 0;
+    pPager->eState = PAGER_OPEN;
+  }
+
+  /* If Pager.errCode is set, the contents of the pager cache cannot be
+  ** trusted. Now that there are no outstanding references to the pager,
+  ** it can safely move back to PAGER_OPEN state. This happens in both
+  ** normal and exclusive-locking mode.
+  */
+  assert( pPager->errCode==SQLITE_OK || !MEMDB );
+  if( pPager->errCode ){
+    if( pPager->tempFile==0 ){
+      pager_reset(pPager);
+      pPager->changeCountDone = 0;
+      pPager->eState = PAGER_OPEN;
+    }else{
+      pPager->eState = (isOpen(pPager->jfd) ? PAGER_OPEN : PAGER_READER);
+    }
+    if( USEFETCH(pPager) ) sqlite3OsUnfetch(pPager->fd, 0, 0);
+    pPager->errCode = SQLITE_OK;
+  }
+
+  pPager->journalOff = 0;
+  pPager->journalHdr = 0;
+  pPager->setMaster = 0;
+}
+
+/*
+** This function is called whenever an IOERR or FULL error that requires
+** the pager to transition into the ERROR state may ahve occurred.
+** The first argument is a pointer to the pager structure, the second 
+** the error-code about to be returned by a pager API function. The 
+** value returned is a copy of the second argument to this function. 
+**
+** If the second argument is SQLITE_FULL, SQLITE_IOERR or one of the
+** IOERR sub-codes, the pager enters the ERROR state and the error code
+** is stored in Pager.errCode. While the pager remains in the ERROR state,
+** all major API calls on the Pager will immediately return Pager.errCode.
+**
+** The ERROR state indicates that the contents of the pager-cache 
+** cannot be trusted. This state can be cleared by completely discarding 
+** the contents of the pager-cache. If a transaction was active when
+** the persistent error occurred, then the rollback journal may need
+** to be replayed to restore the contents of the database file (as if
+** it were a hot-journal).
+*/
+static int pager_error(Pager *pPager, int rc){
+  int rc2 = rc & 0xff;
+  assert( rc==SQLITE_OK || !MEMDB );
+  assert(
+       pPager->errCode==SQLITE_FULL ||
+       pPager->errCode==SQLITE_OK ||
+       (pPager->errCode & 0xff)==SQLITE_IOERR
+  );
+  if( rc2==SQLITE_FULL || rc2==SQLITE_IOERR ){
+    pPager->errCode = rc;
+    pPager->eState = PAGER_ERROR;
+  }
+  return rc;
+}
+
+static int pager_truncate(Pager *pPager, Pgno nPage);
+
+/*
+** The write transaction open on pPager is being committed (bCommit==1)
+** or rolled back (bCommit==0).
+**
+** Return TRUE if and only if all dirty pages should be flushed to disk.
+**
+** Rules:
+**
+**   *  For non-TEMP databases, always sync to disk.  This is necessary
+**      for transactions to be durable.
+**
+**   *  Sync TEMP database only on a COMMIT (not a ROLLBACK) when the backing
+**      file has been created already (via a spill on pagerStress()) and
+**      when the number of dirty pages in memory exceeds 25% of the total
+**      cache size.
+*/
+static int pagerFlushOnCommit(Pager *pPager, int bCommit){
+  if( pPager->tempFile==0 ) return 1;
+  if( !bCommit ) return 0;
+  if( !isOpen(pPager->fd) ) return 0;
+  return (sqlite3PCachePercentDirty(pPager->pPCache)>=25);
+}
+
+/*
+** This routine ends a transaction. A transaction is usually ended by 
+** either a COMMIT or a ROLLBACK operation. This routine may be called 
+** after rollback of a hot-journal, or if an error occurs while opening
+** the journal file or writing the very first journal-header of a
+** database transaction.
+** 
+** This routine is never called in PAGER_ERROR state. If it is called
+** in PAGER_NONE or PAGER_SHARED state and the lock held is less
+** exclusive than a RESERVED lock, it is a no-op.
+**
+** Otherwise, any active savepoints are released.
+**
+** If the journal file is open, then it is "finalized". Once a journal 
+** file has been finalized it is not possible to use it to roll back a 
+** transaction. Nor will it be considered to be a hot-journal by this
+** or any other database connection. Exactly how a journal is finalized
+** depends on whether or not the pager is running in exclusive mode and
+** the current journal-mode (Pager.journalMode value), as follows:
+**
+**   journalMode==MEMORY
+**     Journal file descriptor is simply closed. This destroys an 
+**     in-memory journal.
+**
+**   journalMode==TRUNCATE
+**     Journal file is truncated to zero bytes in size.
+**
+**   journalMode==PERSIST
+**     The first 28 bytes of the journal file are zeroed. This invalidates
+**     the first journal header in the file, and hence the entire journal
+**     file. An invalid journal file cannot be rolled back.
+**
+**   journalMode==DELETE
+**     The journal file is closed and deleted using sqlite3OsDelete().
+**
+**     If the pager is running in exclusive mode, this method of finalizing
+**     the journal file is never used. Instead, if the journalMode is
+**     DELETE and the pager is in exclusive mode, the method described under
+**     journalMode==PERSIST is used instead.
+**
+** After the journal is finalized, the pager moves to PAGER_READER state.
+** If running in non-exclusive rollback mode, the lock on the file is 
+** downgraded to a SHARED_LOCK.
+**
+** SQLITE_OK is returned if no error occurs. If an error occurs during
+** any of the IO operations to finalize the journal file or unlock the
+** database then the IO error code is returned to the user. If the 
+** operation to finalize the journal file fails, then the code still
+** tries to unlock the database file if not in exclusive mode. If the
+** unlock operation fails as well, then the first error code related
+** to the first error encountered (the journal finalization one) is
+** returned.
+*/
+static int pager_end_transaction(Pager *pPager, int hasMaster, int bCommit){
+  int rc = SQLITE_OK;      /* Error code from journal finalization operation */
+  int rc2 = SQLITE_OK;     /* Error code from db file unlock operation */
+
+  /* Do nothing if the pager does not have an open write transaction
+  ** or at least a RESERVED lock. This function may be called when there
+  ** is no write-transaction active but a RESERVED or greater lock is
+  ** held under two circumstances:
+  **
+  **   1. After a successful hot-journal rollback, it is called with
+  **      eState==PAGER_NONE and eLock==EXCLUSIVE_LOCK.
+  **
+  **   2. If a connection with locking_mode=exclusive holding an EXCLUSIVE 
+  **      lock switches back to locking_mode=normal and then executes a
+  **      read-transaction, this function is called with eState==PAGER_READER 
+  **      and eLock==EXCLUSIVE_LOCK when the read-transaction is closed.
+  */
+  assert( assert_pager_state(pPager) );
+  assert( pPager->eState!=PAGER_ERROR );
+  if( pPager->eState<PAGER_WRITER_LOCKED && pPager->eLock<RESERVED_LOCK ){
+    return SQLITE_OK;
+  }
+
+  releaseAllSavepoints(pPager);
+  assert( isOpen(pPager->jfd) || pPager->pInJournal==0 );
+  if( isOpen(pPager->jfd) ){
+    assert( !pagerUseWal(pPager) );
+
+    /* Finalize the journal file. */
+    if( sqlite3JournalIsInMemory(pPager->jfd) ){
+      /* assert( pPager->journalMode==PAGER_JOURNALMODE_MEMORY ); */
+      sqlite3OsClose(pPager->jfd);
+    }else if( pPager->journalMode==PAGER_JOURNALMODE_TRUNCATE ){
+      if( pPager->journalOff==0 ){
+        rc = SQLITE_OK;
+      }else{
+        rc = sqlite3OsTruncate(pPager->jfd, 0);
+        if( rc==SQLITE_OK && pPager->fullSync ){
+          /* Make sure the new file size is written into the inode right away.
+          ** Otherwise the journal might resurrect following a power loss and
+          ** cause the last transaction to roll back.  See
+          ** https://bugzilla.mozilla.org/show_bug.cgi?id=1072773
+          */
+          rc = sqlite3OsSync(pPager->jfd, pPager->syncFlags);
+        }
+      }
+      pPager->journalOff = 0;
+    }else if( pPager->journalMode==PAGER_JOURNALMODE_PERSIST
+      || (pPager->exclusiveMode && pPager->journalMode!=PAGER_JOURNALMODE_WAL)
+    ){
+      rc = zeroJournalHdr(pPager, hasMaster||pPager->tempFile);
+      pPager->journalOff = 0;
+    }else{
+      /* This branch may be executed with Pager.journalMode==MEMORY if
+      ** a hot-journal was just rolled back. In this case the journal
+      ** file should be closed and deleted. If this connection writes to
+      ** the database file, it will do so using an in-memory journal.
+      */
+      int bDelete = !pPager->tempFile;
+      assert( sqlite3JournalIsInMemory(pPager->jfd)==0 );
+      assert( pPager->journalMode==PAGER_JOURNALMODE_DELETE 
+           || pPager->journalMode==PAGER_JOURNALMODE_MEMORY 
+           || pPager->journalMode==PAGER_JOURNALMODE_WAL 
+      );
+      sqlite3OsClose(pPager->jfd);
+      if( bDelete ){
+        rc = sqlite3OsDelete(pPager->pVfs, pPager->zJournal, pPager->extraSync);
+      }
+    }
+  }
+
+#ifdef SQLITE_CHECK_PAGES
+  sqlite3PcacheIterateDirty(pPager->pPCache, pager_set_pagehash);
+  if( pPager->dbSize==0 && sqlite3PcacheRefCount(pPager->pPCache)>0 ){
+    PgHdr *p = sqlite3PagerLookup(pPager, 1);
+    if( p ){
+      p->pageHash = 0;
+      sqlite3PagerUnrefNotNull(p);
+    }
+  }
+#endif
+
+  sqlite3BitvecDestroy(pPager->pInJournal);
+  pPager->pInJournal = 0;
+  pPager->nRec = 0;
+  if( rc==SQLITE_OK ){
+    if( pagerFlushOnCommit(pPager, bCommit) ){
+      sqlite3PcacheCleanAll(pPager->pPCache);
+    }else{
+      sqlite3PcacheClearWritable(pPager->pPCache);
+    }
+    sqlite3PcacheTruncate(pPager->pPCache, pPager->dbSize);
+  }
+
+  if( pagerUseWal(pPager) ){
+    /* Drop the WAL write-lock, if any. Also, if the connection was in 
+    ** locking_mode=exclusive mode but is no longer, drop the EXCLUSIVE 
+    ** lock held on the database file.
+    */
+    rc2 = sqlite3WalEndWriteTransaction(pPager->pWal);
+    assert( rc2==SQLITE_OK );
+  }else if( rc==SQLITE_OK && bCommit && pPager->dbFileSize>pPager->dbSize ){
+    /* This branch is taken when committing a transaction in rollback-journal
+    ** mode if the database file on disk is larger than the database image.
+    ** At this point the journal has been finalized and the transaction 
+    ** successfully committed, but the EXCLUSIVE lock is still held on the
+    ** file. So it is safe to truncate the database file to its minimum
+    ** required size.  */
+    assert( pPager->eLock==EXCLUSIVE_LOCK );
+    rc = pager_truncate(pPager, pPager->dbSize);
+  }
+
+  if( rc==SQLITE_OK && bCommit && isOpen(pPager->fd) ){
+    rc = sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_COMMIT_PHASETWO, 0);
+    if( rc==SQLITE_NOTFOUND ) rc = SQLITE_OK;
+  }
+
+  if( !pPager->exclusiveMode 
+   && (!pagerUseWal(pPager) || sqlite3WalExclusiveMode(pPager->pWal, 0))
+  ){
+    rc2 = pagerUnlockDb(pPager, SHARED_LOCK);
+    pPager->changeCountDone = 0;
+  }
+  pPager->eState = PAGER_READER;
+  pPager->setMaster = 0;
+
+  return (rc==SQLITE_OK?rc2:rc);
+}
+
+/*
+** Execute a rollback if a transaction is active and unlock the 
+** database file. 
+**
+** If the pager has already entered the ERROR state, do not attempt 
+** the rollback at this time. Instead, pager_unlock() is called. The
+** call to pager_unlock() will discard all in-memory pages, unlock
+** the database file and move the pager back to OPEN state. If this 
+** means that there is a hot-journal left in the file-system, the next 
+** connection to obtain a shared lock on the pager (which may be this one) 
+** will roll it back.
+**
+** If the pager has not already entered the ERROR state, but an IO or
+** malloc error occurs during a rollback, then this will itself cause 
+** the pager to enter the ERROR state. Which will be cleared by the
+** call to pager_unlock(), as described above.
+*/
+static void pagerUnlockAndRollback(Pager *pPager){
+  if( pPager->eState!=PAGER_ERROR && pPager->eState!=PAGER_OPEN ){
+    assert( assert_pager_state(pPager) );
+    if( pPager->eState>=PAGER_WRITER_LOCKED ){
+      sqlite3BeginBenignMalloc();
+      sqlite3PagerRollback(pPager);
+      sqlite3EndBenignMalloc();
+    }else if( !pPager->exclusiveMode ){
+      assert( pPager->eState==PAGER_READER );
+      pager_end_transaction(pPager, 0, 0);
+    }
+  }
+  pager_unlock(pPager);
+}
+
+/*
+** Parameter aData must point to a buffer of pPager->pageSize bytes
+** of data. Compute and return a checksum based ont the contents of the 
+** page of data and the current value of pPager->cksumInit.
+**
+** This is not a real checksum. It is really just the sum of the 
+** random initial value (pPager->cksumInit) and every 200th byte
+** of the page data, starting with byte offset (pPager->pageSize%200).
+** Each byte is interpreted as an 8-bit unsigned integer.
+**
+** Changing the formula used to compute this checksum results in an
+** incompatible journal file format.
+**
+** If journal corruption occurs due to a power failure, the most likely 
+** scenario is that one end or the other of the record will be changed. 
+** It is much less likely that the two ends of the journal record will be
+** correct and the middle be corrupt.  Thus, this "checksum" scheme,
+** though fast and simple, catches the mostly likely kind of corruption.
+*/
+static u32 pager_cksum(Pager *pPager, const u8 *aData){
+  u32 cksum = pPager->cksumInit;         /* Checksum value to return */
+  int i = pPager->pageSize-200;          /* Loop counter */
+  while( i>0 ){
+    cksum += aData[i];
+    i -= 200;
+  }
+  return cksum;
+}
+
+/*
+** Report the current page size and number of reserved bytes back
+** to the codec.
+*/
+#ifdef SQLITE_HAS_CODEC
+static void pagerReportSize(Pager *pPager){
+  if( pPager->xCodecSizeChng ){
+    pPager->xCodecSizeChng(pPager->pCodec, pPager->pageSize,
+                           (int)pPager->nReserve);
+  }
+}
+#else
+# define pagerReportSize(X)     /* No-op if we do not support a codec */
+#endif
+
+#ifdef SQLITE_HAS_CODEC
+/*
+** Make sure the number of reserved bits is the same in the destination
+** pager as it is in the source.  This comes up when a VACUUM changes the
+** number of reserved bits to the "optimal" amount.
+*/
+SQLITE_PRIVATE void sqlite3PagerAlignReserve(Pager *pDest, Pager *pSrc){
+  if( pDest->nReserve!=pSrc->nReserve ){
+    pDest->nReserve = pSrc->nReserve;
+    pagerReportSize(pDest);
+  }
+}
+#endif
+
+/*
+** Read a single page from either the journal file (if isMainJrnl==1) or
+** from the sub-journal (if isMainJrnl==0) and playback that page.
+** The page begins at offset *pOffset into the file. The *pOffset
+** value is increased to the start of the next page in the journal.
+**
+** The main rollback journal uses checksums - the statement journal does 
+** not.
+**
+** If the page number of the page record read from the (sub-)journal file
+** is greater than the current value of Pager.dbSize, then playback is
+** skipped and SQLITE_OK is returned.
+**
+** If pDone is not NULL, then it is a record of pages that have already
+** been played back.  If the page at *pOffset has already been played back
+** (if the corresponding pDone bit is set) then skip the playback.
+** Make sure the pDone bit corresponding to the *pOffset page is set
+** prior to returning.
+**
+** If the page record is successfully read from the (sub-)journal file
+** and played back, then SQLITE_OK is returned. If an IO error occurs
+** while reading the record from the (sub-)journal file or while writing
+** to the database file, then the IO error code is returned. If data
+** is successfully read from the (sub-)journal file but appears to be
+** corrupted, SQLITE_DONE is returned. Data is considered corrupted in
+** two circumstances:
+** 
+**   * If the record page-number is illegal (0 or PAGER_MJ_PGNO), or
+**   * If the record is being rolled back from the main journal file
+**     and the checksum field does not match the record content.
+**
+** Neither of these two scenarios are possible during a savepoint rollback.
+**
+** If this is a savepoint rollback, then memory may have to be dynamically
+** allocated by this function. If this is the case and an allocation fails,
+** SQLITE_NOMEM is returned.
+*/
+static int pager_playback_one_page(
+  Pager *pPager,                /* The pager being played back */
+  i64 *pOffset,                 /* Offset of record to playback */
+  Bitvec *pDone,                /* Bitvec of pages already played back */
+  int isMainJrnl,               /* 1 -> main journal. 0 -> sub-journal. */
+  int isSavepnt                 /* True for a savepoint rollback */
+){
+  int rc;
+  PgHdr *pPg;                   /* An existing page in the cache */
+  Pgno pgno;                    /* The page number of a page in journal */
+  u32 cksum;                    /* Checksum used for sanity checking */
+  char *aData;                  /* Temporary storage for the page */
+  sqlite3_file *jfd;            /* The file descriptor for the journal file */
+  int isSynced;                 /* True if journal page is synced */
+
+  assert( (isMainJrnl&~1)==0 );      /* isMainJrnl is 0 or 1 */
+  assert( (isSavepnt&~1)==0 );       /* isSavepnt is 0 or 1 */
+  assert( isMainJrnl || pDone );     /* pDone always used on sub-journals */
+  assert( isSavepnt || pDone==0 );   /* pDone never used on non-savepoint */
+
+  aData = pPager->pTmpSpace;
+  assert( aData );         /* Temp storage must have already been allocated */
+  assert( pagerUseWal(pPager)==0 || (!isMainJrnl && isSavepnt) );
+
+  /* Either the state is greater than PAGER_WRITER_CACHEMOD (a transaction 
+  ** or savepoint rollback done at the request of the caller) or this is
+  ** a hot-journal rollback. If it is a hot-journal rollback, the pager
+  ** is in state OPEN and holds an EXCLUSIVE lock. Hot-journal rollback
+  ** only reads from the main journal, not the sub-journal.
+  */
+  assert( pPager->eState>=PAGER_WRITER_CACHEMOD
+       || (pPager->eState==PAGER_OPEN && pPager->eLock==EXCLUSIVE_LOCK)
+  );
+  assert( pPager->eState>=PAGER_WRITER_CACHEMOD || isMainJrnl );
+
+  /* Read the page number and page data from the journal or sub-journal
+  ** file. Return an error code to the caller if an IO error occurs.
+  */
+  jfd = isMainJrnl ? pPager->jfd : pPager->sjfd;
+  rc = read32bits(jfd, *pOffset, &pgno);
+  if( rc!=SQLITE_OK ) return rc;
+  rc = sqlite3OsRead(jfd, (u8*)aData, pPager->pageSize, (*pOffset)+4);
+  if( rc!=SQLITE_OK ) return rc;
+  *pOffset += pPager->pageSize + 4 + isMainJrnl*4;
+
+  /* Sanity checking on the page.  This is more important that I originally
+  ** thought.  If a power failure occurs while the journal is being written,
+  ** it could cause invalid data to be written into the journal.  We need to
+  ** detect this invalid data (with high probability) and ignore it.
+  */
+  if( pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){
+    assert( !isSavepnt );
+    return SQLITE_DONE;
+  }
+  if( pgno>(Pgno)pPager->dbSize || sqlite3BitvecTest(pDone, pgno) ){
+    return SQLITE_OK;
+  }
+  if( isMainJrnl ){
+    rc = read32bits(jfd, (*pOffset)-4, &cksum);
+    if( rc ) return rc;
+    if( !isSavepnt && pager_cksum(pPager, (u8*)aData)!=cksum ){
+      return SQLITE_DONE;
+    }
+  }
+
+  /* If this page has already been played back before during the current
+  ** rollback, then don't bother to play it back again.
+  */
+  if( pDone && (rc = sqlite3BitvecSet(pDone, pgno))!=SQLITE_OK ){
+    return rc;
+  }
+
+  /* When playing back page 1, restore the nReserve setting
+  */
+  if( pgno==1 && pPager->nReserve!=((u8*)aData)[20] ){
+    pPager->nReserve = ((u8*)aData)[20];
+    pagerReportSize(pPager);
+  }
+
+  /* If the pager is in CACHEMOD state, then there must be a copy of this
+  ** page in the pager cache. In this case just update the pager cache,
+  ** not the database file. The page is left marked dirty in this case.
+  **
+  ** An exception to the above rule: If the database is in no-sync mode
+  ** and a page is moved during an incremental vacuum then the page may
+  ** not be in the pager cache. Later: if a malloc() or IO error occurs
+  ** during a Movepage() call, then the page may not be in the cache
+  ** either. So the condition described in the above paragraph is not
+  ** assert()able.
+  **
+  ** If in WRITER_DBMOD, WRITER_FINISHED or OPEN state, then we update the
+  ** pager cache if it exists and the main file. The page is then marked 
+  ** not dirty. Since this code is only executed in PAGER_OPEN state for
+  ** a hot-journal rollback, it is guaranteed that the page-cache is empty
+  ** if the pager is in OPEN state.
+  **
+  ** Ticket #1171:  The statement journal might contain page content that is
+  ** different from the page content at the start of the transaction.
+  ** This occurs when a page is changed prior to the start of a statement
+  ** then changed again within the statement.  When rolling back such a
+  ** statement we must not write to the original database unless we know
+  ** for certain that original page contents are synced into the main rollback
+  ** journal.  Otherwise, a power loss might leave modified data in the
+  ** database file without an entry in the rollback journal that can
+  ** restore the database to its original form.  Two conditions must be
+  ** met before writing to the database files. (1) the database must be
+  ** locked.  (2) we know that the original page content is fully synced
+  ** in the main journal either because the page is not in cache or else
+  ** the page is marked as needSync==0.
+  **
+  ** 2008-04-14:  When attempting to vacuum a corrupt database file, it
+  ** is possible to fail a statement on a database that does not yet exist.
+  ** Do not attempt to write if database file has never been opened.
+  */
+  if( pagerUseWal(pPager) ){
+    pPg = 0;
+  }else{
+    pPg = sqlite3PagerLookup(pPager, pgno);
+  }
+  assert( pPg || !MEMDB );
+  assert( pPager->eState!=PAGER_OPEN || pPg==0 || pPager->tempFile );
+  PAGERTRACE(("PLAYBACK %d page %d hash(%08x) %s\n",
+           PAGERID(pPager), pgno, pager_datahash(pPager->pageSize, (u8*)aData),
+           (isMainJrnl?"main-journal":"sub-journal")
+  ));
+  if( isMainJrnl ){
+    isSynced = pPager->noSync || (*pOffset <= pPager->journalHdr);
+  }else{
+    isSynced = (pPg==0 || 0==(pPg->flags & PGHDR_NEED_SYNC));
+  }
+  if( isOpen(pPager->fd)
+   && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN)
+   && isSynced
+  ){
+    i64 ofst = (pgno-1)*(i64)pPager->pageSize;
+    testcase( !isSavepnt && pPg!=0 && (pPg->flags&PGHDR_NEED_SYNC)!=0 );
+    assert( !pagerUseWal(pPager) );
+    rc = sqlite3OsWrite(pPager->fd, (u8 *)aData, pPager->pageSize, ofst);
+    if( pgno>pPager->dbFileSize ){
+      pPager->dbFileSize = pgno;
+    }
+    if( pPager->pBackup ){
+      CODEC1(pPager, aData, pgno, 3, rc=SQLITE_NOMEM_BKPT);
+      sqlite3BackupUpdate(pPager->pBackup, pgno, (u8*)aData);
+      CODEC2(pPager, aData, pgno, 7, rc=SQLITE_NOMEM_BKPT, aData);
+    }
+  }else if( !isMainJrnl && pPg==0 ){
+    /* If this is a rollback of a savepoint and data was not written to
+    ** the database and the page is not in-memory, there is a potential
+    ** problem. When the page is next fetched by the b-tree layer, it 
+    ** will be read from the database file, which may or may not be 
+    ** current. 
+    **
+    ** There are a couple of different ways this can happen. All are quite
+    ** obscure. When running in synchronous mode, this can only happen 
+    ** if the page is on the free-list at the start of the transaction, then
+    ** populated, then moved using sqlite3PagerMovepage().
+    **
+    ** The solution is to add an in-memory page to the cache containing
+    ** the data just read from the sub-journal. Mark the page as dirty 
+    ** and if the pager requires a journal-sync, then mark the page as 
+    ** requiring a journal-sync before it is written.
+    */
+    assert( isSavepnt );
+    assert( (pPager->doNotSpill & SPILLFLAG_ROLLBACK)==0 );
+    pPager->doNotSpill |= SPILLFLAG_ROLLBACK;
+    rc = sqlite3PagerGet(pPager, pgno, &pPg, 1);
+    assert( (pPager->doNotSpill & SPILLFLAG_ROLLBACK)!=0 );
+    pPager->doNotSpill &= ~SPILLFLAG_ROLLBACK;
+    if( rc!=SQLITE_OK ) return rc;
+    sqlite3PcacheMakeDirty(pPg);
+  }
+  if( pPg ){
+    /* No page should ever be explicitly rolled back that is in use, except
+    ** for page 1 which is held in use in order to keep the lock on the
+    ** database active. However such a page may be rolled back as a result
+    ** of an internal error resulting in an automatic call to
+    ** sqlite3PagerRollback().
+    */
+    void *pData;
+    pData = pPg->pData;
+    memcpy(pData, (u8*)aData, pPager->pageSize);
+    pPager->xReiniter(pPg);
+    /* It used to be that sqlite3PcacheMakeClean(pPg) was called here.  But
+    ** that call was dangerous and had no detectable benefit since the cache
+    ** is normally cleaned by sqlite3PcacheCleanAll() after rollback and so
+    ** has been removed. */
+    pager_set_pagehash(pPg);
+
+    /* If this was page 1, then restore the value of Pager.dbFileVers.
+    ** Do this before any decoding. */
+    if( pgno==1 ){
+      memcpy(&pPager->dbFileVers, &((u8*)pData)[24],sizeof(pPager->dbFileVers));
+    }
+
+    /* Decode the page just read from disk */
+    CODEC1(pPager, pData, pPg->pgno, 3, rc=SQLITE_NOMEM_BKPT);
+    sqlite3PcacheRelease(pPg);
+  }
+  return rc;
+}
+
+/*
+** Parameter zMaster is the name of a master journal file. A single journal
+** file that referred to the master journal file has just been rolled back.
+** This routine checks if it is possible to delete the master journal file,
+** and does so if it is.
+**
+** Argument zMaster may point to Pager.pTmpSpace. So that buffer is not 
+** available for use within this function.
+**
+** When a master journal file is created, it is populated with the names 
+** of all of its child journals, one after another, formatted as utf-8 
+** encoded text. The end of each child journal file is marked with a 
+** nul-terminator byte (0x00). i.e. the entire contents of a master journal
+** file for a transaction involving two databases might be:
+**
+**   "/home/bill/a.db-journal\x00/home/bill/b.db-journal\x00"
+**
+** A master journal file may only be deleted once all of its child 
+** journals have been rolled back.
+**
+** This function reads the contents of the master-journal file into 
+** memory and loops through each of the child journal names. For
+** each child journal, it checks if:
+**
+**   * if the child journal exists, and if so
+**   * if the child journal contains a reference to master journal 
+**     file zMaster
+**
+** If a child journal can be found that matches both of the criteria
+** above, this function returns without doing anything. Otherwise, if
+** no such child journal can be found, file zMaster is deleted from
+** the file-system using sqlite3OsDelete().
+**
+** If an IO error within this function, an error code is returned. This
+** function allocates memory by calling sqlite3Malloc(). If an allocation
+** fails, SQLITE_NOMEM is returned. Otherwise, if no IO or malloc errors 
+** occur, SQLITE_OK is returned.
+**
+** TODO: This function allocates a single block of memory to load
+** the entire contents of the master journal file. This could be
+** a couple of kilobytes or so - potentially larger than the page 
+** size.
+*/
+static int pager_delmaster(Pager *pPager, const char *zMaster){
+  sqlite3_vfs *pVfs = pPager->pVfs;
+  int rc;                   /* Return code */
+  sqlite3_file *pMaster;    /* Malloc'd master-journal file descriptor */
+  sqlite3_file *pJournal;   /* Malloc'd child-journal file descriptor */
+  char *zMasterJournal = 0; /* Contents of master journal file */
+  i64 nMasterJournal;       /* Size of master journal file */
+  char *zJournal;           /* Pointer to one journal within MJ file */
+  char *zMasterPtr;         /* Space to hold MJ filename from a journal file */
+  int nMasterPtr;           /* Amount of space allocated to zMasterPtr[] */
+
+  /* Allocate space for both the pJournal and pMaster file descriptors.
+  ** If successful, open the master journal file for reading.
+  */
+  pMaster = (sqlite3_file *)sqlite3MallocZero(pVfs->szOsFile * 2);
+  pJournal = (sqlite3_file *)(((u8 *)pMaster) + pVfs->szOsFile);
+  if( !pMaster ){
+    rc = SQLITE_NOMEM_BKPT;
+  }else{
+    const int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_MASTER_JOURNAL);
+    rc = sqlite3OsOpen(pVfs, zMaster, pMaster, flags, 0);
+  }
+  if( rc!=SQLITE_OK ) goto delmaster_out;
+
+  /* Load the entire master journal file into space obtained from
+  ** sqlite3_malloc() and pointed to by zMasterJournal.   Also obtain
+  ** sufficient space (in zMasterPtr) to hold the names of master
+  ** journal files extracted from regular rollback-journals.
+  */
+  rc = sqlite3OsFileSize(pMaster, &nMasterJournal);
+  if( rc!=SQLITE_OK ) goto delmaster_out;
+  nMasterPtr = pVfs->mxPathname+1;
+  zMasterJournal = sqlite3Malloc(nMasterJournal + nMasterPtr + 1);
+  if( !zMasterJournal ){
+    rc = SQLITE_NOMEM_BKPT;
+    goto delmaster_out;
+  }
+  zMasterPtr = &zMasterJournal[nMasterJournal+1];
+  rc = sqlite3OsRead(pMaster, zMasterJournal, (int)nMasterJournal, 0);
+  if( rc!=SQLITE_OK ) goto delmaster_out;
+  zMasterJournal[nMasterJournal] = 0;
+
+  zJournal = zMasterJournal;
+  while( (zJournal-zMasterJournal)<nMasterJournal ){
+    int exists;
+    rc = sqlite3OsAccess(pVfs, zJournal, SQLITE_ACCESS_EXISTS, &exists);
+    if( rc!=SQLITE_OK ){
+      goto delmaster_out;
+    }
+    if( exists ){
+      /* One of the journals pointed to by the master journal exists.
+      ** Open it and check if it points at the master journal. If
+      ** so, return without deleting the master journal file.
+      */
+      int c;
+      int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_MAIN_JOURNAL);
+      rc = sqlite3OsOpen(pVfs, zJournal, pJournal, flags, 0);
+      if( rc!=SQLITE_OK ){
+        goto delmaster_out;
+      }
+
+      rc = readMasterJournal(pJournal, zMasterPtr, nMasterPtr);
+      sqlite3OsClose(pJournal);
+      if( rc!=SQLITE_OK ){
+        goto delmaster_out;
+      }
+
+      c = zMasterPtr[0]!=0 && strcmp(zMasterPtr, zMaster)==0;
+      if( c ){
+        /* We have a match. Do not delete the master journal file. */
+        goto delmaster_out;
+      }
+    }
+    zJournal += (sqlite3Strlen30(zJournal)+1);
+  }
+ 
+  sqlite3OsClose(pMaster);
+  rc = sqlite3OsDelete(pVfs, zMaster, 0);
+
+delmaster_out:
+  sqlite3_free(zMasterJournal);
+  if( pMaster ){
+    sqlite3OsClose(pMaster);
+    assert( !isOpen(pJournal) );
+    sqlite3_free(pMaster);
+  }
+  return rc;
+}
+
+
+/*
+** This function is used to change the actual size of the database 
+** file in the file-system. This only happens when committing a transaction,
+** or rolling back a transaction (including rolling back a hot-journal).
+**
+** If the main database file is not open, or the pager is not in either
+** DBMOD or OPEN state, this function is a no-op. Otherwise, the size 
+** of the file is changed to nPage pages (nPage*pPager->pageSize bytes). 
+** If the file on disk is currently larger than nPage pages, then use the VFS
+** xTruncate() method to truncate it.
+**
+** Or, it might be the case that the file on disk is smaller than 
+** nPage pages. Some operating system implementations can get confused if 
+** you try to truncate a file to some size that is larger than it 
+** currently is, so detect this case and write a single zero byte to 
+** the end of the new file instead.
+**
+** If successful, return SQLITE_OK. If an IO error occurs while modifying
+** the database file, return the error code to the caller.
+*/
+static int pager_truncate(Pager *pPager, Pgno nPage){
+  int rc = SQLITE_OK;
+  assert( pPager->eState!=PAGER_ERROR );
+  assert( pPager->eState!=PAGER_READER );
+  
+  if( isOpen(pPager->fd) 
+   && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN) 
+  ){
+    i64 currentSize, newSize;
+    int szPage = pPager->pageSize;
+    assert( pPager->eLock==EXCLUSIVE_LOCK );
+    /* TODO: Is it safe to use Pager.dbFileSize here? */
+    rc = sqlite3OsFileSize(pPager->fd, &currentSize);
+    newSize = szPage*(i64)nPage;
+    if( rc==SQLITE_OK && currentSize!=newSize ){
+      if( currentSize>newSize ){
+        rc = sqlite3OsTruncate(pPager->fd, newSize);
+      }else if( (currentSize+szPage)<=newSize ){
+        char *pTmp = pPager->pTmpSpace;
+        memset(pTmp, 0, szPage);
+        testcase( (newSize-szPage) == currentSize );
+        testcase( (newSize-szPage) >  currentSize );
+        rc = sqlite3OsWrite(pPager->fd, pTmp, szPage, newSize-szPage);
+      }
+      if( rc==SQLITE_OK ){
+        pPager->dbFileSize = nPage;
+      }
+    }
+  }
+  return rc;
+}
+
+/*
+** Return a sanitized version of the sector-size of OS file pFile. The
+** return value is guaranteed to lie between 32 and MAX_SECTOR_SIZE.
+*/
+SQLITE_PRIVATE int sqlite3SectorSize(sqlite3_file *pFile){
+  int iRet = sqlite3OsSectorSize(pFile);
+  if( iRet<32 ){
+    iRet = 512;
+  }else if( iRet>MAX_SECTOR_SIZE ){
+    assert( MAX_SECTOR_SIZE>=512 );
+    iRet = MAX_SECTOR_SIZE;
+  }
+  return iRet;
+}
+
+/*
+** Set the value of the Pager.sectorSize variable for the given
+** pager based on the value returned by the xSectorSize method
+** of the open database file. The sector size will be used 
+** to determine the size and alignment of journal header and 
+** master journal pointers within created journal files.
+**
+** For temporary files the effective sector size is always 512 bytes.
+**
+** Otherwise, for non-temporary files, the effective sector size is
+** the value returned by the xSectorSize() method rounded up to 32 if
+** it is less than 32, or rounded down to MAX_SECTOR_SIZE if it
+** is greater than MAX_SECTOR_SIZE.
+**
+** If the file has the SQLITE_IOCAP_POWERSAFE_OVERWRITE property, then set
+** the effective sector size to its minimum value (512).  The purpose of
+** pPager->sectorSize is to define the "blast radius" of bytes that
+** might change if a crash occurs while writing to a single byte in
+** that range.  But with POWERSAFE_OVERWRITE, the blast radius is zero
+** (that is what POWERSAFE_OVERWRITE means), so we minimize the sector
+** size.  For backwards compatibility of the rollback journal file format,
+** we cannot reduce the effective sector size below 512.
+*/
+static void setSectorSize(Pager *pPager){
+  assert( isOpen(pPager->fd) || pPager->tempFile );
+
+  if( pPager->tempFile
+   || (sqlite3OsDeviceCharacteristics(pPager->fd) & 
+              SQLITE_IOCAP_POWERSAFE_OVERWRITE)!=0
+  ){
+    /* Sector size doesn't matter for temporary files. Also, the file
+    ** may not have been opened yet, in which case the OsSectorSize()
+    ** call will segfault. */
+    pPager->sectorSize = 512;
+  }else{
+    pPager->sectorSize = sqlite3SectorSize(pPager->fd);
+  }
+}
+
+/*
+** Playback the journal and thus restore the database file to
+** the state it was in before we started making changes.  
+**
+** The journal file format is as follows: 
+**
+**  (1)  8 byte prefix.  A copy of aJournalMagic[].
+**  (2)  4 byte big-endian integer which is the number of valid page records
+**       in the journal.  If this value is 0xffffffff, then compute the
+**       number of page records from the journal size.
+**  (3)  4 byte big-endian integer which is the initial value for the 
+**       sanity checksum.
+**  (4)  4 byte integer which is the number of pages to truncate the
+**       database to during a rollback.
+**  (5)  4 byte big-endian integer which is the sector size.  The header
+**       is this many bytes in size.
+**  (6)  4 byte big-endian integer which is the page size.
+**  (7)  zero padding out to the next sector size.
+**  (8)  Zero or more pages instances, each as follows:
+**        +  4 byte page number.
+**        +  pPager->pageSize bytes of data.
+**        +  4 byte checksum
+**
+** When we speak of the journal header, we mean the first 7 items above.
+** Each entry in the journal is an instance of the 8th item.
+**
+** Call the value from the second bullet "nRec".  nRec is the number of
+** valid page entries in the journal.  In most cases, you can compute the
+** value of nRec from the size of the journal file.  But if a power
+** failure occurred while the journal was being written, it could be the
+** case that the size of the journal file had already been increased but
+** the extra entries had not yet made it safely to disk.  In such a case,
+** the value of nRec computed from the file size would be too large.  For
+** that reason, we always use the nRec value in the header.
+**
+** If the nRec value is 0xffffffff it means that nRec should be computed
+** from the file size.  This value is used when the user selects the
+** no-sync option for the journal.  A power failure could lead to corruption
+** in this case.  But for things like temporary table (which will be
+** deleted when the power is restored) we don't care.  
+**
+** If the file opened as the journal file is not a well-formed
+** journal file then all pages up to the first corrupted page are rolled
+** back (or no pages if the journal header is corrupted). The journal file
+** is then deleted and SQLITE_OK returned, just as if no corruption had
+** been encountered.
+**
+** If an I/O or malloc() error occurs, the journal-file is not deleted
+** and an error code is returned.
+**
+** The isHot parameter indicates that we are trying to rollback a journal
+** that might be a hot journal.  Or, it could be that the journal is 
+** preserved because of JOURNALMODE_PERSIST or JOURNALMODE_TRUNCATE.
+** If the journal really is hot, reset the pager cache prior rolling
+** back any content.  If the journal is merely persistent, no reset is
+** needed.
+*/
+static int pager_playback(Pager *pPager, int isHot){
+  sqlite3_vfs *pVfs = pPager->pVfs;
+  i64 szJ;                 /* Size of the journal file in bytes */
+  u32 nRec;                /* Number of Records in the journal */
+  u32 u;                   /* Unsigned loop counter */
+  Pgno mxPg = 0;           /* Size of the original file in pages */
+  int rc;                  /* Result code of a subroutine */
+  int res = 1;             /* Value returned by sqlite3OsAccess() */
+  char *zMaster = 0;       /* Name of master journal file if any */
+  int needPagerReset;      /* True to reset page prior to first page rollback */
+  int nPlayback = 0;       /* Total number of pages restored from journal */
+
+  /* Figure out how many records are in the journal.  Abort early if
+  ** the journal is empty.
+  */
+  assert( isOpen(pPager->jfd) );
+  rc = sqlite3OsFileSize(pPager->jfd, &szJ);
+  if( rc!=SQLITE_OK ){
+    goto end_playback;
+  }
+
+  /* Read the master journal name from the journal, if it is present.
+  ** If a master journal file name is specified, but the file is not
+  ** present on disk, then the journal is not hot and does not need to be
+  ** played back.
+  **
+  ** TODO: Technically the following is an error because it assumes that
+  ** buffer Pager.pTmpSpace is (mxPathname+1) bytes or larger. i.e. that
+  ** (pPager->pageSize >= pPager->pVfs->mxPathname+1). Using os_unix.c,
+  ** mxPathname is 512, which is the same as the minimum allowable value
+  ** for pageSize.
+  */
+  zMaster = pPager->pTmpSpace;
+  rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1);
+  if( rc==SQLITE_OK && zMaster[0] ){
+    rc = sqlite3OsAccess(pVfs, zMaster, SQLITE_ACCESS_EXISTS, &res);
+  }
+  zMaster = 0;
+  if( rc!=SQLITE_OK || !res ){
+    goto end_playback;
+  }
+  pPager->journalOff = 0;
+  needPagerReset = isHot;
+
+  /* This loop terminates either when a readJournalHdr() or 
+  ** pager_playback_one_page() call returns SQLITE_DONE or an IO error 
+  ** occurs. 
+  */
+  while( 1 ){
+    /* Read the next journal header from the journal file.  If there are
+    ** not enough bytes left in the journal file for a complete header, or
+    ** it is corrupted, then a process must have failed while writing it.
+    ** This indicates nothing more needs to be rolled back.
+    */
+    rc = readJournalHdr(pPager, isHot, szJ, &nRec, &mxPg);
+    if( rc!=SQLITE_OK ){ 
+      if( rc==SQLITE_DONE ){
+        rc = SQLITE_OK;
+      }
+      goto end_playback;
+    }
+
+    /* If nRec is 0xffffffff, then this journal was created by a process
+    ** working in no-sync mode. This means that the rest of the journal
+    ** file consists of pages, there are no more journal headers. Compute
+    ** the value of nRec based on this assumption.
+    */
+    if( nRec==0xffffffff ){
+      assert( pPager->journalOff==JOURNAL_HDR_SZ(pPager) );
+      nRec = (int)((szJ - JOURNAL_HDR_SZ(pPager))/JOURNAL_PG_SZ(pPager));
+    }
+
+    /* If nRec is 0 and this rollback is of a transaction created by this
+    ** process and if this is the final header in the journal, then it means
+    ** that this part of the journal was being filled but has not yet been
+    ** synced to disk.  Compute the number of pages based on the remaining
+    ** size of the file.
+    **
+    ** The third term of the test was added to fix ticket #2565.
+    ** When rolling back a hot journal, nRec==0 always means that the next
+    ** chunk of the journal contains zero pages to be rolled back.  But
+    ** when doing a ROLLBACK and the nRec==0 chunk is the last chunk in
+    ** the journal, it means that the journal might contain additional
+    ** pages that need to be rolled back and that the number of pages 
+    ** should be computed based on the journal file size.
+    */
+    if( nRec==0 && !isHot &&
+        pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff ){
+      nRec = (int)((szJ - pPager->journalOff) / JOURNAL_PG_SZ(pPager));
+    }
+
+    /* If this is the first header read from the journal, truncate the
+    ** database file back to its original size.
+    */
+    if( pPager->journalOff==JOURNAL_HDR_SZ(pPager) ){
+      rc = pager_truncate(pPager, mxPg);
+      if( rc!=SQLITE_OK ){
+        goto end_playback;
+      }
+      pPager->dbSize = mxPg;
+    }
+
+    /* Copy original pages out of the journal and back into the 
+    ** database file and/or page cache.
+    */
+    for(u=0; u<nRec; u++){
+      if( needPagerReset ){
+        pager_reset(pPager);
+        needPagerReset = 0;
+      }
+      rc = pager_playback_one_page(pPager,&pPager->journalOff,0,1,0);
+      if( rc==SQLITE_OK ){
+        nPlayback++;
+      }else{
+        if( rc==SQLITE_DONE ){
+          pPager->journalOff = szJ;
+          break;
+        }else if( rc==SQLITE_IOERR_SHORT_READ ){
+          /* If the journal has been truncated, simply stop reading and
+          ** processing the journal. This might happen if the journal was
+          ** not completely written and synced prior to a crash.  In that
+          ** case, the database should have never been written in the
+          ** first place so it is OK to simply abandon the rollback. */
+          rc = SQLITE_OK;
+          goto end_playback;
+        }else{
+          /* If we are unable to rollback, quit and return the error
+          ** code.  This will cause the pager to enter the error state
+          ** so that no further harm will be done.  Perhaps the next
+          ** process to come along will be able to rollback the database.
+          */
+          goto end_playback;
+        }
+      }
+    }
+  }
+  /*NOTREACHED*/
+  assert( 0 );
+
+end_playback:
+  /* Following a rollback, the database file should be back in its original
+  ** state prior to the start of the transaction, so invoke the
+  ** SQLITE_FCNTL_DB_UNCHANGED file-control method to disable the
+  ** assertion that the transaction counter was modified.
+  */
+#ifdef SQLITE_DEBUG
+  if( pPager->fd->pMethods ){
+    sqlite3OsFileControlHint(pPager->fd,SQLITE_FCNTL_DB_UNCHANGED,0);
+  }
+#endif
+
+  /* If this playback is happening automatically as a result of an IO or 
+  ** malloc error that occurred after the change-counter was updated but 
+  ** before the transaction was committed, then the change-counter 
+  ** modification may just have been reverted. If this happens in exclusive 
+  ** mode, then subsequent transactions performed by the connection will not
+  ** update the change-counter at all. This may lead to cache inconsistency
+  ** problems for other processes at some point in the future. So, just
+  ** in case this has happened, clear the changeCountDone flag now.
+  */
+  pPager->changeCountDone = pPager->tempFile;
+
+  if( rc==SQLITE_OK ){
+    zMaster = pPager->pTmpSpace;
+    rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1);
+    testcase( rc!=SQLITE_OK );
+  }
+  if( rc==SQLITE_OK
+   && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN)
+  ){
+    rc = sqlite3PagerSync(pPager, 0);
+  }
+  if( rc==SQLITE_OK ){
+    rc = pager_end_transaction(pPager, zMaster[0]!='\0', 0);
+    testcase( rc!=SQLITE_OK );
+  }
+  if( rc==SQLITE_OK && zMaster[0] && res ){
+    /* If there was a master journal and this routine will return success,
+    ** see if it is possible to delete the master journal.
+    */
+    rc = pager_delmaster(pPager, zMaster);
+    testcase( rc!=SQLITE_OK );
+  }
+  if( isHot && nPlayback ){
+    sqlite3_log(SQLITE_NOTICE_RECOVER_ROLLBACK, "recovered %d pages from %s",
+                nPlayback, pPager->zJournal);
+  }
+
+  /* The Pager.sectorSize variable may have been updated while rolling
+  ** back a journal created by a process with a different sector size
+  ** value. Reset it to the correct value for this process.
+  */
+  setSectorSize(pPager);
+  return rc;
+}
+
+
+/*
+** Read the content for page pPg out of the database file and into 
+** pPg->pData. A shared lock or greater must be held on the database
+** file before this function is called.
+**
+** If page 1 is read, then the value of Pager.dbFileVers[] is set to
+** the value read from the database file.
+**
+** If an IO error occurs, then the IO error is returned to the caller.
+** Otherwise, SQLITE_OK is returned.
+*/
+static int readDbPage(PgHdr *pPg, u32 iFrame){
+  Pager *pPager = pPg->pPager; /* Pager object associated with page pPg */
+  Pgno pgno = pPg->pgno;       /* Page number to read */
+  int rc = SQLITE_OK;          /* Return code */
+  int pgsz = pPager->pageSize; /* Number of bytes to read */
+
+  assert( pPager->eState>=PAGER_READER && !MEMDB );
+  assert( isOpen(pPager->fd) );
+
+#ifndef SQLITE_OMIT_WAL
+  if( iFrame ){
+    /* Try to pull the page from the write-ahead log. */
+    rc = sqlite3WalReadFrame(pPager->pWal, iFrame, pgsz, pPg->pData);
+  }else
+#endif
+  {
+    i64 iOffset = (pgno-1)*(i64)pPager->pageSize;
+    rc = sqlite3OsRead(pPager->fd, pPg->pData, pgsz, iOffset);
+    if( rc==SQLITE_IOERR_SHORT_READ ){
+      rc = SQLITE_OK;
+    }
+  }
+
+  if( pgno==1 ){
+    if( rc ){
+      /* If the read is unsuccessful, set the dbFileVers[] to something
+      ** that will never be a valid file version.  dbFileVers[] is a copy
+      ** of bytes 24..39 of the database.  Bytes 28..31 should always be
+      ** zero or the size of the database in page. Bytes 32..35 and 35..39
+      ** should be page numbers which are never 0xffffffff.  So filling
+      ** pPager->dbFileVers[] with all 0xff bytes should suffice.
+      **
+      ** For an encrypted database, the situation is more complex:  bytes
+      ** 24..39 of the database are white noise.  But the probability of
+      ** white noise equaling 16 bytes of 0xff is vanishingly small so
+      ** we should still be ok.
+      */
+      memset(pPager->dbFileVers, 0xff, sizeof(pPager->dbFileVers));
+    }else{
+      u8 *dbFileVers = &((u8*)pPg->pData)[24];
+      memcpy(&pPager->dbFileVers, dbFileVers, sizeof(pPager->dbFileVers));
+    }
+  }
+  CODEC1(pPager, pPg->pData, pgno, 3, rc = SQLITE_NOMEM_BKPT);
+
+  PAGER_INCR(sqlite3_pager_readdb_count);
+  PAGER_INCR(pPager->nRead);
+  IOTRACE(("PGIN %p %d\n", pPager, pgno));
+  PAGERTRACE(("FETCH %d page %d hash(%08x)\n",
+               PAGERID(pPager), pgno, pager_pagehash(pPg)));
+
+  return rc;
+}
+
+/*
+** Update the value of the change-counter at offsets 24 and 92 in
+** the header and the sqlite version number at offset 96.
+**
+** This is an unconditional update.  See also the pager_incr_changecounter()
+** routine which only updates the change-counter if the update is actually
+** needed, as determined by the pPager->changeCountDone state variable.
+*/
+static void pager_write_changecounter(PgHdr *pPg){
+  u32 change_counter;
+
+  /* Increment the value just read and write it back to byte 24. */
+  change_counter = sqlite3Get4byte((u8*)pPg->pPager->dbFileVers)+1;
+  put32bits(((char*)pPg->pData)+24, change_counter);
+
+  /* Also store the SQLite version number in bytes 96..99 and in
+  ** bytes 92..95 store the change counter for which the version number
+  ** is valid. */
+  put32bits(((char*)pPg->pData)+92, change_counter);
+  put32bits(((char*)pPg->pData)+96, SQLITE_VERSION_NUMBER);
+}
+
+#ifndef SQLITE_OMIT_WAL
+/*
+** This function is invoked once for each page that has already been 
+** written into the log file when a WAL transaction is rolled back.
+** Parameter iPg is the page number of said page. The pCtx argument 
+** is actually a pointer to the Pager structure.
+**
+** If page iPg is present in the cache, and has no outstanding references,
+** it is discarded. Otherwise, if there are one or more outstanding
+** references, the page content is reloaded from the database. If the
+** attempt to reload content from the database is required and fails, 
+** return an SQLite error code. Otherwise, SQLITE_OK.
+*/
+static int pagerUndoCallback(void *pCtx, Pgno iPg){
+  int rc = SQLITE_OK;
+  Pager *pPager = (Pager *)pCtx;
+  PgHdr *pPg;
+
+  assert( pagerUseWal(pPager) );
+  pPg = sqlite3PagerLookup(pPager, iPg);
+  if( pPg ){
+    if( sqlite3PcachePageRefcount(pPg)==1 ){
+      sqlite3PcacheDrop(pPg);
+    }else{
+      u32 iFrame = 0;
+      rc = sqlite3WalFindFrame(pPager->pWal, pPg->pgno, &iFrame);
+      if( rc==SQLITE_OK ){
+        rc = readDbPage(pPg, iFrame);
+      }
+      if( rc==SQLITE_OK ){
+        pPager->xReiniter(pPg);
+      }
+      sqlite3PagerUnrefNotNull(pPg);
+    }
+  }
+
+  /* Normally, if a transaction is rolled back, any backup processes are
+  ** updated as data is copied out of the rollback journal and into the
+  ** database. This is not generally possible with a WAL database, as
+  ** rollback involves simply truncating the log file. Therefore, if one
+  ** or more frames have already been written to the log (and therefore 
+  ** also copied into the backup databases) as part of this transaction,
+  ** the backups must be restarted.
+  */
+  sqlite3BackupRestart(pPager->pBackup);
+
+  return rc;
+}
+
+/*
+** This function is called to rollback a transaction on a WAL database.
+*/
+static int pagerRollbackWal(Pager *pPager){
+  int rc;                         /* Return Code */
+  PgHdr *pList;                   /* List of dirty pages to revert */
+
+  /* For all pages in the cache that are currently dirty or have already
+  ** been written (but not committed) to the log file, do one of the 
+  ** following:
+  **
+  **   + Discard the cached page (if refcount==0), or
+  **   + Reload page content from the database (if refcount>0).
+  */
+  pPager->dbSize = pPager->dbOrigSize;
+  rc = sqlite3WalUndo(pPager->pWal, pagerUndoCallback, (void *)pPager);
+  pList = sqlite3PcacheDirtyList(pPager->pPCache);
+  while( pList && rc==SQLITE_OK ){
+    PgHdr *pNext = pList->pDirty;
+    rc = pagerUndoCallback((void *)pPager, pList->pgno);
+    pList = pNext;
+  }
+
+  return rc;
+}
+
+/*
+** This function is a wrapper around sqlite3WalFrames(). As well as logging
+** the contents of the list of pages headed by pList (connected by pDirty),
+** this function notifies any active backup processes that the pages have
+** changed. 
+**
+** The list of pages passed into this routine is always sorted by page number.
+** Hence, if page 1 appears anywhere on the list, it will be the first page.
+*/ 
+static int pagerWalFrames(
+  Pager *pPager,                  /* Pager object */
+  PgHdr *pList,                   /* List of frames to log */
+  Pgno nTruncate,                 /* Database size after this commit */
+  int isCommit                    /* True if this is a commit */
+){
+  int rc;                         /* Return code */
+  int nList;                      /* Number of pages in pList */
+  PgHdr *p;                       /* For looping over pages */
+
+  assert( pPager->pWal );
+  assert( pList );
+#ifdef SQLITE_DEBUG
+  /* Verify that the page list is in accending order */
+  for(p=pList; p && p->pDirty; p=p->pDirty){
+    assert( p->pgno < p->pDirty->pgno );
+  }
+#endif
+
+  assert( pList->pDirty==0 || isCommit );
+  if( isCommit ){
+    /* If a WAL transaction is being committed, there is no point in writing
+    ** any pages with page numbers greater than nTruncate into the WAL file.
+    ** They will never be read by any client. So remove them from the pDirty
+    ** list here. */
+    PgHdr **ppNext = &pList;
+    nList = 0;
+    for(p=pList; (*ppNext = p)!=0; p=p->pDirty){
+      if( p->pgno<=nTruncate ){
+        ppNext = &p->pDirty;
+        nList++;
+      }
+    }
+    assert( pList );
+  }else{
+    nList = 1;
+  }
+  pPager->aStat[PAGER_STAT_WRITE] += nList;
+
+  if( pList->pgno==1 ) pager_write_changecounter(pList);
+  rc = sqlite3WalFrames(pPager->pWal, 
+      pPager->pageSize, pList, nTruncate, isCommit, pPager->walSyncFlags
+  );
+  if( rc==SQLITE_OK && pPager->pBackup ){
+    for(p=pList; p; p=p->pDirty){
+      sqlite3BackupUpdate(pPager->pBackup, p->pgno, (u8 *)p->pData);
+    }
+  }
+
+#ifdef SQLITE_CHECK_PAGES
+  pList = sqlite3PcacheDirtyList(pPager->pPCache);
+  for(p=pList; p; p=p->pDirty){
+    pager_set_pagehash(p);
+  }
+#endif
+
+  return rc;
+}
+
+/*
+** Begin a read transaction on the WAL.
+**
+** This routine used to be called "pagerOpenSnapshot()" because it essentially
+** makes a snapshot of the database at the current point in time and preserves
+** that snapshot for use by the reader in spite of concurrently changes by
+** other writers or checkpointers.
+*/
+static int pagerBeginReadTransaction(Pager *pPager){
+  int rc;                         /* Return code */
+  int changed = 0;                /* True if cache must be reset */
+
+  assert( pagerUseWal(pPager) );
+  assert( pPager->eState==PAGER_OPEN || pPager->eState==PAGER_READER );
+
+  /* sqlite3WalEndReadTransaction() was not called for the previous
+  ** transaction in locking_mode=EXCLUSIVE.  So call it now.  If we
+  ** are in locking_mode=NORMAL and EndRead() was previously called,
+  ** the duplicate call is harmless.
+  */
+  sqlite3WalEndReadTransaction(pPager->pWal);
+
+  rc = sqlite3WalBeginReadTransaction(pPager->pWal, &changed);
+  if( rc!=SQLITE_OK || changed ){
+    pager_reset(pPager);
+    if( USEFETCH(pPager) ) sqlite3OsUnfetch(pPager->fd, 0, 0);
+  }
+
+  return rc;
+}
+#endif
+
+/*
+** This function is called as part of the transition from PAGER_OPEN
+** to PAGER_READER state to determine the size of the database file
+** in pages (assuming the page size currently stored in Pager.pageSize).
+**
+** If no error occurs, SQLITE_OK is returned and the size of the database
+** in pages is stored in *pnPage. Otherwise, an error code (perhaps
+** SQLITE_IOERR_FSTAT) is returned and *pnPage is left unmodified.
+*/
+static int pagerPagecount(Pager *pPager, Pgno *pnPage){
+  Pgno nPage;                     /* Value to return via *pnPage */
+
+  /* Query the WAL sub-system for the database size. The WalDbsize()
+  ** function returns zero if the WAL is not open (i.e. Pager.pWal==0), or
+  ** if the database size is not available. The database size is not
+  ** available from the WAL sub-system if the log file is empty or
+  ** contains no valid committed transactions.
+  */
+  assert( pPager->eState==PAGER_OPEN );
+  assert( pPager->eLock>=SHARED_LOCK );
+  assert( isOpen(pPager->fd) );
+  assert( pPager->tempFile==0 );
+  nPage = sqlite3WalDbsize(pPager->pWal);
+
+  /* If the number of pages in the database is not available from the
+  ** WAL sub-system, determine the page counte based on the size of
+  ** the database file.  If the size of the database file is not an
+  ** integer multiple of the page-size, round up the result.
+  */
+  if( nPage==0 && ALWAYS(isOpen(pPager->fd)) ){
+    i64 n = 0;                    /* Size of db file in bytes */
+    int rc = sqlite3OsFileSize(pPager->fd, &n);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    nPage = (Pgno)((n+pPager->pageSize-1) / pPager->pageSize);
+  }
+
+  /* If the current number of pages in the file is greater than the
+  ** configured maximum pager number, increase the allowed limit so
+  ** that the file can be read.
+  */
+  if( nPage>pPager->mxPgno ){
+    pPager->mxPgno = (Pgno)nPage;
+  }
+
+  *pnPage = nPage;
+  return SQLITE_OK;
+}
+
+#ifndef SQLITE_OMIT_WAL
+/*
+** Check if the *-wal file that corresponds to the database opened by pPager
+** exists if the database is not empy, or verify that the *-wal file does
+** not exist (by deleting it) if the database file is empty.
+**
+** If the database is not empty and the *-wal file exists, open the pager
+** in WAL mode.  If the database is empty or if no *-wal file exists and
+** if no error occurs, make sure Pager.journalMode is not set to
+** PAGER_JOURNALMODE_WAL.
+**
+** Return SQLITE_OK or an error code.
+**
+** The caller must hold a SHARED lock on the database file to call this
+** function. Because an EXCLUSIVE lock on the db file is required to delete 
+** a WAL on a none-empty database, this ensures there is no race condition 
+** between the xAccess() below and an xDelete() being executed by some 
+** other connection.
+*/
+static int pagerOpenWalIfPresent(Pager *pPager){
+  int rc = SQLITE_OK;
+  assert( pPager->eState==PAGER_OPEN );
+  assert( pPager->eLock>=SHARED_LOCK );
+
+  if( !pPager->tempFile ){
+    int isWal;                    /* True if WAL file exists */
+    Pgno nPage;                   /* Size of the database file */
+
+    rc = pagerPagecount(pPager, &nPage);
+    if( rc ) return rc;
+    if( nPage==0 ){
+      rc = sqlite3OsDelete(pPager->pVfs, pPager->zWal, 0);
+      if( rc==SQLITE_IOERR_DELETE_NOENT ) rc = SQLITE_OK;
+      isWal = 0;
+    }else{
+      rc = sqlite3OsAccess(
+          pPager->pVfs, pPager->zWal, SQLITE_ACCESS_EXISTS, &isWal
+      );
+    }
+    if( rc==SQLITE_OK ){
+      if( isWal ){
+        testcase( sqlite3PcachePagecount(pPager->pPCache)==0 );
+        rc = sqlite3PagerOpenWal(pPager, 0);
+      }else if( pPager->journalMode==PAGER_JOURNALMODE_WAL ){
+        pPager->journalMode = PAGER_JOURNALMODE_DELETE;
+      }
+    }
+  }
+  return rc;
+}
+#endif
+
+/*
+** Playback savepoint pSavepoint. Or, if pSavepoint==NULL, then playback
+** the entire master journal file. The case pSavepoint==NULL occurs when 
+** a ROLLBACK TO command is invoked on a SAVEPOINT that is a transaction 
+** savepoint.
+**
+** When pSavepoint is not NULL (meaning a non-transaction savepoint is 
+** being rolled back), then the rollback consists of up to three stages,
+** performed in the order specified:
+**
+**   * Pages are played back from the main journal starting at byte
+**     offset PagerSavepoint.iOffset and continuing to 
+**     PagerSavepoint.iHdrOffset, or to the end of the main journal
+**     file if PagerSavepoint.iHdrOffset is zero.
+**
+**   * If PagerSavepoint.iHdrOffset is not zero, then pages are played
+**     back starting from the journal header immediately following 
+**     PagerSavepoint.iHdrOffset to the end of the main journal file.
+**
+**   * Pages are then played back from the sub-journal file, starting
+**     with the PagerSavepoint.iSubRec and continuing to the end of
+**     the journal file.
+**
+** Throughout the rollback process, each time a page is rolled back, the
+** corresponding bit is set in a bitvec structure (variable pDone in the
+** implementation below). This is used to ensure that a page is only
+** rolled back the first time it is encountered in either journal.
+**
+** If pSavepoint is NULL, then pages are only played back from the main
+** journal file. There is no need for a bitvec in this case.
+**
+** In either case, before playback commences the Pager.dbSize variable
+** is reset to the value that it held at the start of the savepoint 
+** (or transaction). No page with a page-number greater than this value
+** is played back. If one is encountered it is simply skipped.
+*/
+static int pagerPlaybackSavepoint(Pager *pPager, PagerSavepoint *pSavepoint){
+  i64 szJ;                 /* Effective size of the main journal */
+  i64 iHdrOff;             /* End of first segment of main-journal records */
+  int rc = SQLITE_OK;      /* Return code */
+  Bitvec *pDone = 0;       /* Bitvec to ensure pages played back only once */
+
+  assert( pPager->eState!=PAGER_ERROR );
+  assert( pPager->eState>=PAGER_WRITER_LOCKED );
+
+  /* Allocate a bitvec to use to store the set of pages rolled back */
+  if( pSavepoint ){
+    pDone = sqlite3BitvecCreate(pSavepoint->nOrig);
+    if( !pDone ){
+      return SQLITE_NOMEM_BKPT;
+    }
+  }
+
+  /* Set the database size back to the value it was before the savepoint 
+  ** being reverted was opened.
+  */
+  pPager->dbSize = pSavepoint ? pSavepoint->nOrig : pPager->dbOrigSize;
+  pPager->changeCountDone = pPager->tempFile;
+
+  if( !pSavepoint && pagerUseWal(pPager) ){
+    return pagerRollbackWal(pPager);
+  }
+
+  /* Use pPager->journalOff as the effective size of the main rollback
+  ** journal.  The actual file might be larger than this in
+  ** PAGER_JOURNALMODE_TRUNCATE or PAGER_JOURNALMODE_PERSIST.  But anything
+  ** past pPager->journalOff is off-limits to us.
+  */
+  szJ = pPager->journalOff;
+  assert( pagerUseWal(pPager)==0 || szJ==0 );
+
+  /* Begin by rolling back records from the main journal starting at
+  ** PagerSavepoint.iOffset and continuing to the next journal header.
+  ** There might be records in the main journal that have a page number
+  ** greater than the current database size (pPager->dbSize) but those
+  ** will be skipped automatically.  Pages are added to pDone as they
+  ** are played back.
+  */
+  if( pSavepoint && !pagerUseWal(pPager) ){
+    iHdrOff = pSavepoint->iHdrOffset ? pSavepoint->iHdrOffset : szJ;
+    pPager->journalOff = pSavepoint->iOffset;
+    while( rc==SQLITE_OK && pPager->journalOff<iHdrOff ){
+      rc = pager_playback_one_page(pPager, &pPager->journalOff, pDone, 1, 1);
+    }
+    assert( rc!=SQLITE_DONE );
+  }else{
+    pPager->journalOff = 0;
+  }
+
+  /* Continue rolling back records out of the main journal starting at
+  ** the first journal header seen and continuing until the effective end
+  ** of the main journal file.  Continue to skip out-of-range pages and
+  ** continue adding pages rolled back to pDone.
+  */
+  while( rc==SQLITE_OK && pPager->journalOff<szJ ){
+    u32 ii;            /* Loop counter */
+    u32 nJRec = 0;     /* Number of Journal Records */
+    u32 dummy;
+    rc = readJournalHdr(pPager, 0, szJ, &nJRec, &dummy);
+    assert( rc!=SQLITE_DONE );
+
+    /*
+    ** The "pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff"
+    ** test is related to ticket #2565.  See the discussion in the
+    ** pager_playback() function for additional information.
+    */
+    if( nJRec==0 
+     && pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff
+    ){
+      nJRec = (u32)((szJ - pPager->journalOff)/JOURNAL_PG_SZ(pPager));
+    }
+    for(ii=0; rc==SQLITE_OK && ii<nJRec && pPager->journalOff<szJ; ii++){
+      rc = pager_playback_one_page(pPager, &pPager->journalOff, pDone, 1, 1);
+    }
+    assert( rc!=SQLITE_DONE );
+  }
+  assert( rc!=SQLITE_OK || pPager->journalOff>=szJ );
+
+  /* Finally,  rollback pages from the sub-journal.  Page that were
+  ** previously rolled back out of the main journal (and are hence in pDone)
+  ** will be skipped.  Out-of-range pages are also skipped.
+  */
+  if( pSavepoint ){
+    u32 ii;            /* Loop counter */
+    i64 offset = (i64)pSavepoint->iSubRec*(4+pPager->pageSize);
+
+    if( pagerUseWal(pPager) ){
+      rc = sqlite3WalSavepointUndo(pPager->pWal, pSavepoint->aWalData);
+    }
+    for(ii=pSavepoint->iSubRec; rc==SQLITE_OK && ii<pPager->nSubRec; ii++){
+      assert( offset==(i64)ii*(4+pPager->pageSize) );
+      rc = pager_playback_one_page(pPager, &offset, pDone, 0, 1);
+    }
+    assert( rc!=SQLITE_DONE );
+  }
+
+  sqlite3BitvecDestroy(pDone);
+  if( rc==SQLITE_OK ){
+    pPager->journalOff = szJ;
+  }
+
+  return rc;
+}
+
+/*
+** Change the maximum number of in-memory pages that are allowed
+** before attempting to recycle clean and unused pages.
+*/
+SQLITE_PRIVATE void sqlite3PagerSetCachesize(Pager *pPager, int mxPage){
+  sqlite3PcacheSetCachesize(pPager->pPCache, mxPage);
+}
+
+/*
+** Change the maximum number of in-memory pages that are allowed
+** before attempting to spill pages to journal.
+*/
+SQLITE_PRIVATE int sqlite3PagerSetSpillsize(Pager *pPager, int mxPage){
+  return sqlite3PcacheSetSpillsize(pPager->pPCache, mxPage);
+}
+
+/*
+** Invoke SQLITE_FCNTL_MMAP_SIZE based on the current value of szMmap.
+*/
+static void pagerFixMaplimit(Pager *pPager){
+#if SQLITE_MAX_MMAP_SIZE>0
+  sqlite3_file *fd = pPager->fd;
+  if( isOpen(fd) && fd->pMethods->iVersion>=3 ){
+    sqlite3_int64 sz;
+    sz = pPager->szMmap;
+    pPager->bUseFetch = (sz>0);
+    sqlite3OsFileControlHint(pPager->fd, SQLITE_FCNTL_MMAP_SIZE, &sz);
+  }
+#endif
+}
+
+/*
+** Change the maximum size of any memory mapping made of the database file.
+*/
+SQLITE_PRIVATE void sqlite3PagerSetMmapLimit(Pager *pPager, sqlite3_int64 szMmap){
+  pPager->szMmap = szMmap;
+  pagerFixMaplimit(pPager);
+}
+
+/*
+** Free as much memory as possible from the pager.
+*/
+SQLITE_PRIVATE void sqlite3PagerShrink(Pager *pPager){
+  sqlite3PcacheShrink(pPager->pPCache);
+}
+
+/*
+** Adjust settings of the pager to those specified in the pgFlags parameter.
+**
+** The "level" in pgFlags & PAGER_SYNCHRONOUS_MASK sets the robustness
+** of the database to damage due to OS crashes or power failures by
+** changing the number of syncs()s when writing the journals.
+** There are four levels:
+**
+**    OFF       sqlite3OsSync() is never called.  This is the default
+**              for temporary and transient files.
+**
+**    NORMAL    The journal is synced once before writes begin on the
+**              database.  This is normally adequate protection, but
+**              it is theoretically possible, though very unlikely,
+**              that an inopertune power failure could leave the journal
+**              in a state which would cause damage to the database
+**              when it is rolled back.
+**
+**    FULL      The journal is synced twice before writes begin on the
+**              database (with some additional information - the nRec field
+**              of the journal header - being written in between the two
+**              syncs).  If we assume that writing a
+**              single disk sector is atomic, then this mode provides
+**              assurance that the journal will not be corrupted to the
+**              point of causing damage to the database during rollback.
+**
+**    EXTRA     This is like FULL except that is also syncs the directory
+**              that contains the rollback journal after the rollback
+**              journal is unlinked.
+**
+** The above is for a rollback-journal mode.  For WAL mode, OFF continues
+** to mean that no syncs ever occur.  NORMAL means that the WAL is synced
+** prior to the start of checkpoint and that the database file is synced
+** at the conclusion of the checkpoint if the entire content of the WAL
+** was written back into the database.  But no sync operations occur for
+** an ordinary commit in NORMAL mode with WAL.  FULL means that the WAL
+** file is synced following each commit operation, in addition to the
+** syncs associated with NORMAL.  There is no difference between FULL
+** and EXTRA for WAL mode.
+**
+** Do not confuse synchronous=FULL with SQLITE_SYNC_FULL.  The
+** SQLITE_SYNC_FULL macro means to use the MacOSX-style full-fsync
+** using fcntl(F_FULLFSYNC).  SQLITE_SYNC_NORMAL means to do an
+** ordinary fsync() call.  There is no difference between SQLITE_SYNC_FULL
+** and SQLITE_SYNC_NORMAL on platforms other than MacOSX.  But the
+** synchronous=FULL versus synchronous=NORMAL setting determines when
+** the xSync primitive is called and is relevant to all platforms.
+**
+** Numeric values associated with these states are OFF==1, NORMAL=2,
+** and FULL=3.
+*/
+#ifndef SQLITE_OMIT_PAGER_PRAGMAS
+SQLITE_PRIVATE void sqlite3PagerSetFlags(
+  Pager *pPager,        /* The pager to set safety level for */
+  unsigned pgFlags      /* Various flags */
+){
+  unsigned level = pgFlags & PAGER_SYNCHRONOUS_MASK;
+  if( pPager->tempFile ){
+    pPager->noSync = 1;
+    pPager->fullSync = 0;
+    pPager->extraSync = 0;
+  }else{
+    pPager->noSync =  level==PAGER_SYNCHRONOUS_OFF ?1:0;
+    pPager->fullSync = level>=PAGER_SYNCHRONOUS_FULL ?1:0;
+    pPager->extraSync = level==PAGER_SYNCHRONOUS_EXTRA ?1:0;
+  }
+  if( pPager->noSync ){
+    pPager->syncFlags = 0;
+    pPager->ckptSyncFlags = 0;
+  }else if( pgFlags & PAGER_FULLFSYNC ){
+    pPager->syncFlags = SQLITE_SYNC_FULL;
+    pPager->ckptSyncFlags = SQLITE_SYNC_FULL;
+  }else if( pgFlags & PAGER_CKPT_FULLFSYNC ){
+    pPager->syncFlags = SQLITE_SYNC_NORMAL;
+    pPager->ckptSyncFlags = SQLITE_SYNC_FULL;
+  }else{
+    pPager->syncFlags = SQLITE_SYNC_NORMAL;
+    pPager->ckptSyncFlags = SQLITE_SYNC_NORMAL;
+  }
+  pPager->walSyncFlags = pPager->syncFlags;
+  if( pPager->fullSync ){
+    pPager->walSyncFlags |= WAL_SYNC_TRANSACTIONS;
+  }
+  if( pgFlags & PAGER_CACHESPILL ){
+    pPager->doNotSpill &= ~SPILLFLAG_OFF;
+  }else{
+    pPager->doNotSpill |= SPILLFLAG_OFF;
+  }
+}
+#endif
+
+/*
+** The following global variable is incremented whenever the library
+** attempts to open a temporary file.  This information is used for
+** testing and analysis only.  
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_opentemp_count = 0;
+#endif
+
+/*
+** Open a temporary file.
+**
+** Write the file descriptor into *pFile. Return SQLITE_OK on success 
+** or some other error code if we fail. The OS will automatically 
+** delete the temporary file when it is closed.
+**
+** The flags passed to the VFS layer xOpen() call are those specified
+** by parameter vfsFlags ORed with the following:
+**
+**     SQLITE_OPEN_READWRITE
+**     SQLITE_OPEN_CREATE
+**     SQLITE_OPEN_EXCLUSIVE
+**     SQLITE_OPEN_DELETEONCLOSE
+*/
+static int pagerOpentemp(
+  Pager *pPager,        /* The pager object */
+  sqlite3_file *pFile,  /* Write the file descriptor here */
+  int vfsFlags          /* Flags passed through to the VFS */
+){
+  int rc;               /* Return code */
+
+#ifdef SQLITE_TEST
+  sqlite3_opentemp_count++;  /* Used for testing and analysis only */
+#endif
+
+  vfsFlags |=  SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE |
+            SQLITE_OPEN_EXCLUSIVE | SQLITE_OPEN_DELETEONCLOSE;
+  rc = sqlite3OsOpen(pPager->pVfs, 0, pFile, vfsFlags, 0);
+  assert( rc!=SQLITE_OK || isOpen(pFile) );
+  return rc;
+}
+
+/*
+** Set the busy handler function.
+**
+** The pager invokes the busy-handler if sqlite3OsLock() returns 
+** SQLITE_BUSY when trying to upgrade from no-lock to a SHARED lock,
+** or when trying to upgrade from a RESERVED lock to an EXCLUSIVE 
+** lock. It does *not* invoke the busy handler when upgrading from
+** SHARED to RESERVED, or when upgrading from SHARED to EXCLUSIVE
+** (which occurs during hot-journal rollback). Summary:
+**
+**   Transition                        | Invokes xBusyHandler
+**   --------------------------------------------------------
+**   NO_LOCK       -> SHARED_LOCK      | Yes
+**   SHARED_LOCK   -> RESERVED_LOCK    | No
+**   SHARED_LOCK   -> EXCLUSIVE_LOCK   | No
+**   RESERVED_LOCK -> EXCLUSIVE_LOCK   | Yes
+**
+** If the busy-handler callback returns non-zero, the lock is 
+** retried. If it returns zero, then the SQLITE_BUSY error is
+** returned to the caller of the pager API function.
+*/
+SQLITE_PRIVATE void sqlite3PagerSetBusyhandler(
+  Pager *pPager,                       /* Pager object */
+  int (*xBusyHandler)(void *),         /* Pointer to busy-handler function */
+  void *pBusyHandlerArg                /* Argument to pass to xBusyHandler */
+){
+  pPager->xBusyHandler = xBusyHandler;
+  pPager->pBusyHandlerArg = pBusyHandlerArg;
+
+  if( isOpen(pPager->fd) ){
+    void **ap = (void **)&pPager->xBusyHandler;
+    assert( ((int(*)(void *))(ap[0]))==xBusyHandler );
+    assert( ap[1]==pBusyHandlerArg );
+    sqlite3OsFileControlHint(pPager->fd, SQLITE_FCNTL_BUSYHANDLER, (void *)ap);
+  }
+}
+
+/*
+** Change the page size used by the Pager object. The new page size 
+** is passed in *pPageSize.
+**
+** If the pager is in the error state when this function is called, it
+** is a no-op. The value returned is the error state error code (i.e. 
+** one of SQLITE_IOERR, an SQLITE_IOERR_xxx sub-code or SQLITE_FULL).
+**
+** Otherwise, if all of the following are true:
+**
+**   * the new page size (value of *pPageSize) is valid (a power 
+**     of two between 512 and SQLITE_MAX_PAGE_SIZE, inclusive), and
+**
+**   * there are no outstanding page references, and
+**
+**   * the database is either not an in-memory database or it is
+**     an in-memory database that currently consists of zero pages.
+**
+** then the pager object page size is set to *pPageSize.
+**
+** If the page size is changed, then this function uses sqlite3PagerMalloc() 
+** to obtain a new Pager.pTmpSpace buffer. If this allocation attempt 
+** fails, SQLITE_NOMEM is returned and the page size remains unchanged. 
+** In all other cases, SQLITE_OK is returned.
+**
+** If the page size is not changed, either because one of the enumerated
+** conditions above is not true, the pager was in error state when this
+** function was called, or because the memory allocation attempt failed, 
+** then *pPageSize is set to the old, retained page size before returning.
+*/
+SQLITE_PRIVATE int sqlite3PagerSetPagesize(Pager *pPager, u32 *pPageSize, int nReserve){
+  int rc = SQLITE_OK;
+
+  /* It is not possible to do a full assert_pager_state() here, as this
+  ** function may be called from within PagerOpen(), before the state
+  ** of the Pager object is internally consistent.
+  **
+  ** At one point this function returned an error if the pager was in 
+  ** PAGER_ERROR state. But since PAGER_ERROR state guarantees that
+  ** there is at least one outstanding page reference, this function
+  ** is a no-op for that case anyhow.
+  */
+
+  u32 pageSize = *pPageSize;
+  assert( pageSize==0 || (pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE) );
+  if( (pPager->memDb==0 || pPager->dbSize==0)
+   && sqlite3PcacheRefCount(pPager->pPCache)==0 
+   && pageSize && pageSize!=(u32)pPager->pageSize 
+  ){
+    char *pNew = NULL;             /* New temp space */
+    i64 nByte = 0;
+
+    if( pPager->eState>PAGER_OPEN && isOpen(pPager->fd) ){
+      rc = sqlite3OsFileSize(pPager->fd, &nByte);
+    }
+    if( rc==SQLITE_OK ){
+      pNew = (char *)sqlite3PageMalloc(pageSize);
+      if( !pNew ) rc = SQLITE_NOMEM_BKPT;
+    }
+
+    if( rc==SQLITE_OK ){
+      pager_reset(pPager);
+      rc = sqlite3PcacheSetPageSize(pPager->pPCache, pageSize);
+    }
+    if( rc==SQLITE_OK ){
+      sqlite3PageFree(pPager->pTmpSpace);
+      pPager->pTmpSpace = pNew;
+      pPager->dbSize = (Pgno)((nByte+pageSize-1)/pageSize);
+      pPager->pageSize = pageSize;
+    }else{
+      sqlite3PageFree(pNew);
+    }
+  }
+
+  *pPageSize = pPager->pageSize;
+  if( rc==SQLITE_OK ){
+    if( nReserve<0 ) nReserve = pPager->nReserve;
+    assert( nReserve>=0 && nReserve<1000 );
+    pPager->nReserve = (i16)nReserve;
+    pagerReportSize(pPager);
+    pagerFixMaplimit(pPager);
+  }
+  return rc;
+}
+
+/*
+** Return a pointer to the "temporary page" buffer held internally
+** by the pager.  This is a buffer that is big enough to hold the
+** entire content of a database page.  This buffer is used internally
+** during rollback and will be overwritten whenever a rollback
+** occurs.  But other modules are free to use it too, as long as
+** no rollbacks are happening.
+*/
+SQLITE_PRIVATE void *sqlite3PagerTempSpace(Pager *pPager){
+  return pPager->pTmpSpace;
+}
+
+/*
+** Attempt to set the maximum database page count if mxPage is positive. 
+** Make no changes if mxPage is zero or negative.  And never reduce the
+** maximum page count below the current size of the database.
+**
+** Regardless of mxPage, return the current maximum page count.
+*/
+SQLITE_PRIVATE int sqlite3PagerMaxPageCount(Pager *pPager, int mxPage){
+  if( mxPage>0 ){
+    pPager->mxPgno = mxPage;
+  }
+  assert( pPager->eState!=PAGER_OPEN );      /* Called only by OP_MaxPgcnt */
+  assert( pPager->mxPgno>=pPager->dbSize );  /* OP_MaxPgcnt enforces this */
+  return pPager->mxPgno;
+}
+
+/*
+** The following set of routines are used to disable the simulated
+** I/O error mechanism.  These routines are used to avoid simulated
+** errors in places where we do not care about errors.
+**
+** Unless -DSQLITE_TEST=1 is used, these routines are all no-ops
+** and generate no code.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API extern int sqlite3_io_error_pending;
+SQLITE_API extern int sqlite3_io_error_hit;
+static int saved_cnt;
+void disable_simulated_io_errors(void){
+  saved_cnt = sqlite3_io_error_pending;
+  sqlite3_io_error_pending = -1;
+}
+void enable_simulated_io_errors(void){
+  sqlite3_io_error_pending = saved_cnt;
+}
+#else
+# define disable_simulated_io_errors()
+# define enable_simulated_io_errors()
+#endif
+
+/*
+** Read the first N bytes from the beginning of the file into memory
+** that pDest points to. 
+**
+** If the pager was opened on a transient file (zFilename==""), or
+** opened on a file less than N bytes in size, the output buffer is
+** zeroed and SQLITE_OK returned. The rationale for this is that this 
+** function is used to read database headers, and a new transient or
+** zero sized database has a header than consists entirely of zeroes.
+**
+** If any IO error apart from SQLITE_IOERR_SHORT_READ is encountered,
+** the error code is returned to the caller and the contents of the
+** output buffer undefined.
+*/
+SQLITE_PRIVATE int sqlite3PagerReadFileheader(Pager *pPager, int N, unsigned char *pDest){
+  int rc = SQLITE_OK;
+  memset(pDest, 0, N);
+  assert( isOpen(pPager->fd) || pPager->tempFile );
+
+  /* This routine is only called by btree immediately after creating
+  ** the Pager object.  There has not been an opportunity to transition
+  ** to WAL mode yet.
+  */
+  assert( !pagerUseWal(pPager) );
+
+  if( isOpen(pPager->fd) ){
+    IOTRACE(("DBHDR %p 0 %d\n", pPager, N))
+    rc = sqlite3OsRead(pPager->fd, pDest, N, 0);
+    if( rc==SQLITE_IOERR_SHORT_READ ){
+      rc = SQLITE_OK;
+    }
+  }
+  return rc;
+}
+
+/*
+** This function may only be called when a read-transaction is open on
+** the pager. It returns the total number of pages in the database.
+**
+** However, if the file is between 1 and <page-size> bytes in size, then 
+** this is considered a 1 page file.
+*/
+SQLITE_PRIVATE void sqlite3PagerPagecount(Pager *pPager, int *pnPage){
+  assert( pPager->eState>=PAGER_READER );
+  assert( pPager->eState!=PAGER_WRITER_FINISHED );
+  *pnPage = (int)pPager->dbSize;
+}
+
+
+/*
+** Try to obtain a lock of type locktype on the database file. If
+** a similar or greater lock is already held, this function is a no-op
+** (returning SQLITE_OK immediately).
+**
+** Otherwise, attempt to obtain the lock using sqlite3OsLock(). Invoke 
+** the busy callback if the lock is currently not available. Repeat 
+** until the busy callback returns false or until the attempt to 
+** obtain the lock succeeds.
+**
+** Return SQLITE_OK on success and an error code if we cannot obtain
+** the lock. If the lock is obtained successfully, set the Pager.state 
+** variable to locktype before returning.
+*/
+static int pager_wait_on_lock(Pager *pPager, int locktype){
+  int rc;                              /* Return code */
+
+  /* Check that this is either a no-op (because the requested lock is 
+  ** already held), or one of the transitions that the busy-handler
+  ** may be invoked during, according to the comment above
+  ** sqlite3PagerSetBusyhandler().
+  */
+  assert( (pPager->eLock>=locktype)
+       || (pPager->eLock==NO_LOCK && locktype==SHARED_LOCK)
+       || (pPager->eLock==RESERVED_LOCK && locktype==EXCLUSIVE_LOCK)
+  );
+
+  do {
+    rc = pagerLockDb(pPager, locktype);
+  }while( rc==SQLITE_BUSY && pPager->xBusyHandler(pPager->pBusyHandlerArg) );
+  return rc;
+}
+
+/*
+** Function assertTruncateConstraint(pPager) checks that one of the 
+** following is true for all dirty pages currently in the page-cache:
+**
+**   a) The page number is less than or equal to the size of the 
+**      current database image, in pages, OR
+**
+**   b) if the page content were written at this time, it would not
+**      be necessary to write the current content out to the sub-journal
+**      (as determined by function subjRequiresPage()).
+**
+** If the condition asserted by this function were not true, and the
+** dirty page were to be discarded from the cache via the pagerStress()
+** routine, pagerStress() would not write the current page content to
+** the database file. If a savepoint transaction were rolled back after
+** this happened, the correct behavior would be to restore the current
+** content of the page. However, since this content is not present in either
+** the database file or the portion of the rollback journal and 
+** sub-journal rolled back the content could not be restored and the
+** database image would become corrupt. It is therefore fortunate that 
+** this circumstance cannot arise.
+*/
+#if defined(SQLITE_DEBUG)
+static void assertTruncateConstraintCb(PgHdr *pPg){
+  assert( pPg->flags&PGHDR_DIRTY );
+  assert( !subjRequiresPage(pPg) || pPg->pgno<=pPg->pPager->dbSize );
+}
+static void assertTruncateConstraint(Pager *pPager){
+  sqlite3PcacheIterateDirty(pPager->pPCache, assertTruncateConstraintCb);
+}
+#else
+# define assertTruncateConstraint(pPager)
+#endif
+
+/*
+** Truncate the in-memory database file image to nPage pages. This 
+** function does not actually modify the database file on disk. It 
+** just sets the internal state of the pager object so that the 
+** truncation will be done when the current transaction is committed.
+**
+** This function is only called right before committing a transaction.
+** Once this function has been called, the transaction must either be
+** rolled back or committed. It is not safe to call this function and
+** then continue writing to the database.
+*/
+SQLITE_PRIVATE void sqlite3PagerTruncateImage(Pager *pPager, Pgno nPage){
+  assert( pPager->dbSize>=nPage );
+  assert( pPager->eState>=PAGER_WRITER_CACHEMOD );
+  pPager->dbSize = nPage;
+
+  /* At one point the code here called assertTruncateConstraint() to
+  ** ensure that all pages being truncated away by this operation are,
+  ** if one or more savepoints are open, present in the savepoint 
+  ** journal so that they can be restored if the savepoint is rolled
+  ** back. This is no longer necessary as this function is now only
+  ** called right before committing a transaction. So although the 
+  ** Pager object may still have open savepoints (Pager.nSavepoint!=0), 
+  ** they cannot be rolled back. So the assertTruncateConstraint() call
+  ** is no longer correct. */
+}
+
+
+/*
+** This function is called before attempting a hot-journal rollback. It
+** syncs the journal file to disk, then sets pPager->journalHdr to the
+** size of the journal file so that the pager_playback() routine knows
+** that the entire journal file has been synced.
+**
+** Syncing a hot-journal to disk before attempting to roll it back ensures 
+** that if a power-failure occurs during the rollback, the process that
+** attempts rollback following system recovery sees the same journal
+** content as this process.
+**
+** If everything goes as planned, SQLITE_OK is returned. Otherwise, 
+** an SQLite error code.
+*/
+static int pagerSyncHotJournal(Pager *pPager){
+  int rc = SQLITE_OK;
+  if( !pPager->noSync ){
+    rc = sqlite3OsSync(pPager->jfd, SQLITE_SYNC_NORMAL);
+  }
+  if( rc==SQLITE_OK ){
+    rc = sqlite3OsFileSize(pPager->jfd, &pPager->journalHdr);
+  }
+  return rc;
+}
+
+/*
+** Obtain a reference to a memory mapped page object for page number pgno. 
+** The new object will use the pointer pData, obtained from xFetch().
+** If successful, set *ppPage to point to the new page reference
+** and return SQLITE_OK. Otherwise, return an SQLite error code and set
+** *ppPage to zero.
+**
+** Page references obtained by calling this function should be released
+** by calling pagerReleaseMapPage().
+*/
+static int pagerAcquireMapPage(
+  Pager *pPager,                  /* Pager object */
+  Pgno pgno,                      /* Page number */
+  void *pData,                    /* xFetch()'d data for this page */
+  PgHdr **ppPage                  /* OUT: Acquired page object */
+){
+  PgHdr *p;                       /* Memory mapped page to return */
+  
+  if( pPager->pMmapFreelist ){
+    *ppPage = p = pPager->pMmapFreelist;
+    pPager->pMmapFreelist = p->pDirty;
+    p->pDirty = 0;
+    memset(p->pExtra, 0, pPager->nExtra);
+  }else{
+    *ppPage = p = (PgHdr *)sqlite3MallocZero(sizeof(PgHdr) + pPager->nExtra);
+    if( p==0 ){
+      sqlite3OsUnfetch(pPager->fd, (i64)(pgno-1) * pPager->pageSize, pData);
+      return SQLITE_NOMEM_BKPT;
+    }
+    p->pExtra = (void *)&p[1];
+    p->flags = PGHDR_MMAP;
+    p->nRef = 1;
+    p->pPager = pPager;
+  }
+
+  assert( p->pExtra==(void *)&p[1] );
+  assert( p->pPage==0 );
+  assert( p->flags==PGHDR_MMAP );
+  assert( p->pPager==pPager );
+  assert( p->nRef==1 );
+
+  p->pgno = pgno;
+  p->pData = pData;
+  pPager->nMmapOut++;
+
+  return SQLITE_OK;
+}
+
+/*
+** Release a reference to page pPg. pPg must have been returned by an 
+** earlier call to pagerAcquireMapPage().
+*/
+static void pagerReleaseMapPage(PgHdr *pPg){
+  Pager *pPager = pPg->pPager;
+  pPager->nMmapOut--;
+  pPg->pDirty = pPager->pMmapFreelist;
+  pPager->pMmapFreelist = pPg;
+
+  assert( pPager->fd->pMethods->iVersion>=3 );
+  sqlite3OsUnfetch(pPager->fd, (i64)(pPg->pgno-1)*pPager->pageSize, pPg->pData);
+}
+
+/*
+** Free all PgHdr objects stored in the Pager.pMmapFreelist list.
+*/
+static void pagerFreeMapHdrs(Pager *pPager){
+  PgHdr *p;
+  PgHdr *pNext;
+  for(p=pPager->pMmapFreelist; p; p=pNext){
+    pNext = p->pDirty;
+    sqlite3_free(p);
+  }
+}
+
+
+/*
+** Shutdown the page cache.  Free all memory and close all files.
+**
+** If a transaction was in progress when this routine is called, that
+** transaction is rolled back.  All outstanding pages are invalidated
+** and their memory is freed.  Any attempt to use a page associated
+** with this page cache after this function returns will likely
+** result in a coredump.
+**
+** This function always succeeds. If a transaction is active an attempt
+** is made to roll it back. If an error occurs during the rollback 
+** a hot journal may be left in the filesystem but no error is returned
+** to the caller.
+*/
+SQLITE_PRIVATE int sqlite3PagerClose(Pager *pPager){
+  u8 *pTmp = (u8 *)pPager->pTmpSpace;
+
+  assert( assert_pager_state(pPager) );
+  disable_simulated_io_errors();
+  sqlite3BeginBenignMalloc();
+  pagerFreeMapHdrs(pPager);
+  /* pPager->errCode = 0; */
+  pPager->exclusiveMode = 0;
+#ifndef SQLITE_OMIT_WAL
+  sqlite3WalClose(pPager->pWal, pPager->ckptSyncFlags, pPager->pageSize, pTmp);
+  pPager->pWal = 0;
+#endif
+  pager_reset(pPager);
+  if( MEMDB ){
+    pager_unlock(pPager);
+  }else{
+    /* If it is open, sync the journal file before calling UnlockAndRollback.
+    ** If this is not done, then an unsynced portion of the open journal 
+    ** file may be played back into the database. If a power failure occurs 
+    ** while this is happening, the database could become corrupt.
+    **
+    ** If an error occurs while trying to sync the journal, shift the pager
+    ** into the ERROR state. This causes UnlockAndRollback to unlock the
+    ** database and close the journal file without attempting to roll it
+    ** back or finalize it. The next database user will have to do hot-journal
+    ** rollback before accessing the database file.
+    */
+    if( isOpen(pPager->jfd) ){
+      pager_error(pPager, pagerSyncHotJournal(pPager));
+    }
+    pagerUnlockAndRollback(pPager);
+  }
+  sqlite3EndBenignMalloc();
+  enable_simulated_io_errors();
+  PAGERTRACE(("CLOSE %d\n", PAGERID(pPager)));
+  IOTRACE(("CLOSE %p\n", pPager))
+  sqlite3OsClose(pPager->jfd);
+  sqlite3OsClose(pPager->fd);
+  sqlite3PageFree(pTmp);
+  sqlite3PcacheClose(pPager->pPCache);
+
+#ifdef SQLITE_HAS_CODEC
+  if( pPager->xCodecFree ) pPager->xCodecFree(pPager->pCodec);
+#endif
+
+  assert( !pPager->aSavepoint && !pPager->pInJournal );
+  assert( !isOpen(pPager->jfd) && !isOpen(pPager->sjfd) );
+
+  sqlite3_free(pPager);
+  return SQLITE_OK;
+}
+
+#if !defined(NDEBUG) || defined(SQLITE_TEST)
+/*
+** Return the page number for page pPg.
+*/
+SQLITE_PRIVATE Pgno sqlite3PagerPagenumber(DbPage *pPg){
+  return pPg->pgno;
+}
+#endif
+
+/*
+** Increment the reference count for page pPg.
+*/
+SQLITE_PRIVATE void sqlite3PagerRef(DbPage *pPg){
+  sqlite3PcacheRef(pPg);
+}
+
+/*
+** Sync the journal. In other words, make sure all the pages that have
+** been written to the journal have actually reached the surface of the
+** disk and can be restored in the event of a hot-journal rollback.
+**
+** If the Pager.noSync flag is set, then this function is a no-op.
+** Otherwise, the actions required depend on the journal-mode and the 
+** device characteristics of the file-system, as follows:
+**
+**   * If the journal file is an in-memory journal file, no action need
+**     be taken.
+**
+**   * Otherwise, if the device does not support the SAFE_APPEND property,
+**     then the nRec field of the most recently written journal header
+**     is updated to contain the number of journal records that have
+**     been written following it. If the pager is operating in full-sync
+**     mode, then the journal file is synced before this field is updated.
+**
+**   * If the device does not support the SEQUENTIAL property, then 
+**     journal file is synced.
+**
+** Or, in pseudo-code:
+**
+**   if( NOT <in-memory journal> ){
+**     if( NOT SAFE_APPEND ){
+**       if( <full-sync mode> ) xSync(<journal file>);
+**       <update nRec field>
+**     } 
+**     if( NOT SEQUENTIAL ) xSync(<journal file>);
+**   }
+**
+** If successful, this routine clears the PGHDR_NEED_SYNC flag of every 
+** page currently held in memory before returning SQLITE_OK. If an IO
+** error is encountered, then the IO error code is returned to the caller.
+*/
+static int syncJournal(Pager *pPager, int newHdr){
+  int rc;                         /* Return code */
+
+  assert( pPager->eState==PAGER_WRITER_CACHEMOD
+       || pPager->eState==PAGER_WRITER_DBMOD
+  );
+  assert( assert_pager_state(pPager) );
+  assert( !pagerUseWal(pPager) );
+
+  rc = sqlite3PagerExclusiveLock(pPager);
+  if( rc!=SQLITE_OK ) return rc;
+
+  if( !pPager->noSync ){
+    assert( !pPager->tempFile );
+    if( isOpen(pPager->jfd) && pPager->journalMode!=PAGER_JOURNALMODE_MEMORY ){
+      const int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
+      assert( isOpen(pPager->jfd) );
+
+      if( 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){
+        /* This block deals with an obscure problem. If the last connection
+        ** that wrote to this database was operating in persistent-journal
+        ** mode, then the journal file may at this point actually be larger
+        ** than Pager.journalOff bytes. If the next thing in the journal
+        ** file happens to be a journal-header (written as part of the
+        ** previous connection's transaction), and a crash or power-failure 
+        ** occurs after nRec is updated but before this connection writes 
+        ** anything else to the journal file (or commits/rolls back its 
+        ** transaction), then SQLite may become confused when doing the 
+        ** hot-journal rollback following recovery. It may roll back all
+        ** of this connections data, then proceed to rolling back the old,
+        ** out-of-date data that follows it. Database corruption.
+        **
+        ** To work around this, if the journal file does appear to contain
+        ** a valid header following Pager.journalOff, then write a 0x00
+        ** byte to the start of it to prevent it from being recognized.
+        **
+        ** Variable iNextHdrOffset is set to the offset at which this
+        ** problematic header will occur, if it exists. aMagic is used 
+        ** as a temporary buffer to inspect the first couple of bytes of
+        ** the potential journal header.
+        */
+        i64 iNextHdrOffset;
+        u8 aMagic[8];
+        u8 zHeader[sizeof(aJournalMagic)+4];
+
+        memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic));
+        put32bits(&zHeader[sizeof(aJournalMagic)], pPager->nRec);
+
+        iNextHdrOffset = journalHdrOffset(pPager);
+        rc = sqlite3OsRead(pPager->jfd, aMagic, 8, iNextHdrOffset);
+        if( rc==SQLITE_OK && 0==memcmp(aMagic, aJournalMagic, 8) ){
+          static const u8 zerobyte = 0;
+          rc = sqlite3OsWrite(pPager->jfd, &zerobyte, 1, iNextHdrOffset);
+        }
+        if( rc!=SQLITE_OK && rc!=SQLITE_IOERR_SHORT_READ ){
+          return rc;
+        }
+
+        /* Write the nRec value into the journal file header. If in
+        ** full-synchronous mode, sync the journal first. This ensures that
+        ** all data has really hit the disk before nRec is updated to mark
+        ** it as a candidate for rollback.
+        **
+        ** This is not required if the persistent media supports the
+        ** SAFE_APPEND property. Because in this case it is not possible 
+        ** for garbage data to be appended to the file, the nRec field
+        ** is populated with 0xFFFFFFFF when the journal header is written
+        ** and never needs to be updated.
+        */
+        if( pPager->fullSync && 0==(iDc&SQLITE_IOCAP_SEQUENTIAL) ){
+          PAGERTRACE(("SYNC journal of %d\n", PAGERID(pPager)));
+          IOTRACE(("JSYNC %p\n", pPager))
+          rc = sqlite3OsSync(pPager->jfd, pPager->syncFlags);
+          if( rc!=SQLITE_OK ) return rc;
+        }
+        IOTRACE(("JHDR %p %lld\n", pPager, pPager->journalHdr));
+        rc = sqlite3OsWrite(
+            pPager->jfd, zHeader, sizeof(zHeader), pPager->journalHdr
+        );
+        if( rc!=SQLITE_OK ) return rc;
+      }
+      if( 0==(iDc&SQLITE_IOCAP_SEQUENTIAL) ){
+        PAGERTRACE(("SYNC journal of %d\n", PAGERID(pPager)));
+        IOTRACE(("JSYNC %p\n", pPager))
+        rc = sqlite3OsSync(pPager->jfd, pPager->syncFlags| 
+          (pPager->syncFlags==SQLITE_SYNC_FULL?SQLITE_SYNC_DATAONLY:0)
+        );
+        if( rc!=SQLITE_OK ) return rc;
+      }
+
+      pPager->journalHdr = pPager->journalOff;
+      if( newHdr && 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){
+        pPager->nRec = 0;
+        rc = writeJournalHdr(pPager);
+        if( rc!=SQLITE_OK ) return rc;
+      }
+    }else{
+      pPager->journalHdr = pPager->journalOff;
+    }
+  }
+
+  /* Unless the pager is in noSync mode, the journal file was just 
+  ** successfully synced. Either way, clear the PGHDR_NEED_SYNC flag on 
+  ** all pages.
+  */
+  sqlite3PcacheClearSyncFlags(pPager->pPCache);
+  pPager->eState = PAGER_WRITER_DBMOD;
+  assert( assert_pager_state(pPager) );
+  return SQLITE_OK;
+}
+
+/*
+** The argument is the first in a linked list of dirty pages connected
+** by the PgHdr.pDirty pointer. This function writes each one of the
+** in-memory pages in the list to the database file. The argument may
+** be NULL, representing an empty list. In this case this function is
+** a no-op.
+**
+** The pager must hold at least a RESERVED lock when this function
+** is called. Before writing anything to the database file, this lock
+** is upgraded to an EXCLUSIVE lock. If the lock cannot be obtained,
+** SQLITE_BUSY is returned and no data is written to the database file.
+** 
+** If the pager is a temp-file pager and the actual file-system file
+** is not yet open, it is created and opened before any data is 
+** written out.
+**
+** Once the lock has been upgraded and, if necessary, the file opened,
+** the pages are written out to the database file in list order. Writing
+** a page is skipped if it meets either of the following criteria:
+**
+**   * The page number is greater than Pager.dbSize, or
+**   * The PGHDR_DONT_WRITE flag is set on the page.
+**
+** If writing out a page causes the database file to grow, Pager.dbFileSize
+** is updated accordingly. If page 1 is written out, then the value cached
+** in Pager.dbFileVers[] is updated to match the new value stored in
+** the database file.
+**
+** If everything is successful, SQLITE_OK is returned. If an IO error 
+** occurs, an IO error code is returned. Or, if the EXCLUSIVE lock cannot
+** be obtained, SQLITE_BUSY is returned.
+*/
+static int pager_write_pagelist(Pager *pPager, PgHdr *pList){
+  int rc = SQLITE_OK;                  /* Return code */
+
+  /* This function is only called for rollback pagers in WRITER_DBMOD state. */
+  assert( !pagerUseWal(pPager) );
+  assert( pPager->tempFile || pPager->eState==PAGER_WRITER_DBMOD );
+  assert( pPager->eLock==EXCLUSIVE_LOCK );
+  assert( isOpen(pPager->fd) || pList->pDirty==0 );
+
+  /* If the file is a temp-file has not yet been opened, open it now. It
+  ** is not possible for rc to be other than SQLITE_OK if this branch
+  ** is taken, as pager_wait_on_lock() is a no-op for temp-files.
+  */
+  if( !isOpen(pPager->fd) ){
+    assert( pPager->tempFile && rc==SQLITE_OK );
+    rc = pagerOpentemp(pPager, pPager->fd, pPager->vfsFlags);
+  }
+
+  /* Before the first write, give the VFS a hint of what the final
+  ** file size will be.
+  */
+  assert( rc!=SQLITE_OK || isOpen(pPager->fd) );
+  if( rc==SQLITE_OK 
+   && pPager->dbHintSize<pPager->dbSize
+   && (pList->pDirty || pList->pgno>pPager->dbHintSize)
+  ){
+    sqlite3_int64 szFile = pPager->pageSize * (sqlite3_int64)pPager->dbSize;
+    sqlite3OsFileControlHint(pPager->fd, SQLITE_FCNTL_SIZE_HINT, &szFile);
+    pPager->dbHintSize = pPager->dbSize;
+  }
+
+  while( rc==SQLITE_OK && pList ){
+    Pgno pgno = pList->pgno;
+
+    /* If there are dirty pages in the page cache with page numbers greater
+    ** than Pager.dbSize, this means sqlite3PagerTruncateImage() was called to
+    ** make the file smaller (presumably by auto-vacuum code). Do not write
+    ** any such pages to the file.
+    **
+    ** Also, do not write out any page that has the PGHDR_DONT_WRITE flag
+    ** set (set by sqlite3PagerDontWrite()).
+    */
+    if( pgno<=pPager->dbSize && 0==(pList->flags&PGHDR_DONT_WRITE) ){
+      i64 offset = (pgno-1)*(i64)pPager->pageSize;   /* Offset to write */
+      char *pData;                                   /* Data to write */    
+
+      assert( (pList->flags&PGHDR_NEED_SYNC)==0 );
+      if( pList->pgno==1 ) pager_write_changecounter(pList);
+
+      /* Encode the database */
+      CODEC2(pPager, pList->pData, pgno, 6, return SQLITE_NOMEM_BKPT, pData);
+
+      /* Write out the page data. */
+      rc = sqlite3OsWrite(pPager->fd, pData, pPager->pageSize, offset);
+
+      /* If page 1 was just written, update Pager.dbFileVers to match
+      ** the value now stored in the database file. If writing this 
+      ** page caused the database file to grow, update dbFileSize. 
+      */
+      if( pgno==1 ){
+        memcpy(&pPager->dbFileVers, &pData[24], sizeof(pPager->dbFileVers));
+      }
+      if( pgno>pPager->dbFileSize ){
+        pPager->dbFileSize = pgno;
+      }
+      pPager->aStat[PAGER_STAT_WRITE]++;
+
+      /* Update any backup objects copying the contents of this pager. */
+      sqlite3BackupUpdate(pPager->pBackup, pgno, (u8*)pList->pData);
+
+      PAGERTRACE(("STORE %d page %d hash(%08x)\n",
+                   PAGERID(pPager), pgno, pager_pagehash(pList)));
+      IOTRACE(("PGOUT %p %d\n", pPager, pgno));
+      PAGER_INCR(sqlite3_pager_writedb_count);
+    }else{
+      PAGERTRACE(("NOSTORE %d page %d\n", PAGERID(pPager), pgno));
+    }
+    pager_set_pagehash(pList);
+    pList = pList->pDirty;
+  }
+
+  return rc;
+}
+
+/*
+** Ensure that the sub-journal file is open. If it is already open, this 
+** function is a no-op.
+**
+** SQLITE_OK is returned if everything goes according to plan. An 
+** SQLITE_IOERR_XXX error code is returned if a call to sqlite3OsOpen() 
+** fails.
+*/
+static int openSubJournal(Pager *pPager){
+  int rc = SQLITE_OK;
+  if( !isOpen(pPager->sjfd) ){
+    const int flags =  SQLITE_OPEN_SUBJOURNAL | SQLITE_OPEN_READWRITE 
+      | SQLITE_OPEN_CREATE | SQLITE_OPEN_EXCLUSIVE 
+      | SQLITE_OPEN_DELETEONCLOSE;
+    int nStmtSpill = sqlite3Config.nStmtSpill;
+    if( pPager->journalMode==PAGER_JOURNALMODE_MEMORY || pPager->subjInMemory ){
+      nStmtSpill = -1;
+    }
+    rc = sqlite3JournalOpen(pPager->pVfs, 0, pPager->sjfd, flags, nStmtSpill);
+  }
+  return rc;
+}
+
+/*
+** Append a record of the current state of page pPg to the sub-journal. 
+**
+** If successful, set the bit corresponding to pPg->pgno in the bitvecs
+** for all open savepoints before returning.
+**
+** This function returns SQLITE_OK if everything is successful, an IO
+** error code if the attempt to write to the sub-journal fails, or 
+** SQLITE_NOMEM if a malloc fails while setting a bit in a savepoint
+** bitvec.
+*/
+static int subjournalPage(PgHdr *pPg){
+  int rc = SQLITE_OK;
+  Pager *pPager = pPg->pPager;
+  if( pPager->journalMode!=PAGER_JOURNALMODE_OFF ){
+
+    /* Open the sub-journal, if it has not already been opened */
+    assert( pPager->useJournal );
+    assert( isOpen(pPager->jfd) || pagerUseWal(pPager) );
+    assert( isOpen(pPager->sjfd) || pPager->nSubRec==0 );
+    assert( pagerUseWal(pPager) 
+         || pageInJournal(pPager, pPg) 
+         || pPg->pgno>pPager->dbOrigSize 
+    );
+    rc = openSubJournal(pPager);
+
+    /* If the sub-journal was opened successfully (or was already open),
+    ** write the journal record into the file.  */
+    if( rc==SQLITE_OK ){
+      void *pData = pPg->pData;
+      i64 offset = (i64)pPager->nSubRec*(4+pPager->pageSize);
+      char *pData2;
+  
+      CODEC2(pPager, pData, pPg->pgno, 7, return SQLITE_NOMEM_BKPT, pData2);
+      PAGERTRACE(("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno));
+      rc = write32bits(pPager->sjfd, offset, pPg->pgno);
+      if( rc==SQLITE_OK ){
+        rc = sqlite3OsWrite(pPager->sjfd, pData2, pPager->pageSize, offset+4);
+      }
+    }
+  }
+  if( rc==SQLITE_OK ){
+    pPager->nSubRec++;
+    assert( pPager->nSavepoint>0 );
+    rc = addToSavepointBitvecs(pPager, pPg->pgno);
+  }
+  return rc;
+}
+static int subjournalPageIfRequired(PgHdr *pPg){
+  if( subjRequiresPage(pPg) ){
+    return subjournalPage(pPg);
+  }else{
+    return SQLITE_OK;
+  }
+}
+
+/*
+** This function is called by the pcache layer when it has reached some
+** soft memory limit. The first argument is a pointer to a Pager object
+** (cast as a void*). The pager is always 'purgeable' (not an in-memory
+** database). The second argument is a reference to a page that is 
+** currently dirty but has no outstanding references. The page
+** is always associated with the Pager object passed as the first 
+** argument.
+**
+** The job of this function is to make pPg clean by writing its contents
+** out to the database file, if possible. This may involve syncing the
+** journal file. 
+**
+** If successful, sqlite3PcacheMakeClean() is called on the page and
+** SQLITE_OK returned. If an IO error occurs while trying to make the
+** page clean, the IO error code is returned. If the page cannot be
+** made clean for some other reason, but no error occurs, then SQLITE_OK
+** is returned by sqlite3PcacheMakeClean() is not called.
+*/
+static int pagerStress(void *p, PgHdr *pPg){
+  Pager *pPager = (Pager *)p;
+  int rc = SQLITE_OK;
+
+  assert( pPg->pPager==pPager );
+  assert( pPg->flags&PGHDR_DIRTY );
+
+  /* The doNotSpill NOSYNC bit is set during times when doing a sync of
+  ** journal (and adding a new header) is not allowed.  This occurs
+  ** during calls to sqlite3PagerWrite() while trying to journal multiple
+  ** pages belonging to the same sector.
+  **
+  ** The doNotSpill ROLLBACK and OFF bits inhibits all cache spilling
+  ** regardless of whether or not a sync is required.  This is set during
+  ** a rollback or by user request, respectively.
+  **
+  ** Spilling is also prohibited when in an error state since that could
+  ** lead to database corruption.   In the current implementation it 
+  ** is impossible for sqlite3PcacheFetch() to be called with createFlag==3
+  ** while in the error state, hence it is impossible for this routine to
+  ** be called in the error state.  Nevertheless, we include a NEVER()
+  ** test for the error state as a safeguard against future changes.
+  */
+  if( NEVER(pPager->errCode) ) return SQLITE_OK;
+  testcase( pPager->doNotSpill & SPILLFLAG_ROLLBACK );
+  testcase( pPager->doNotSpill & SPILLFLAG_OFF );
+  testcase( pPager->doNotSpill & SPILLFLAG_NOSYNC );
+  if( pPager->doNotSpill
+   && ((pPager->doNotSpill & (SPILLFLAG_ROLLBACK|SPILLFLAG_OFF))!=0
+      || (pPg->flags & PGHDR_NEED_SYNC)!=0)
+  ){
+    return SQLITE_OK;
+  }
+
+  pPg->pDirty = 0;
+  if( pagerUseWal(pPager) ){
+    /* Write a single frame for this page to the log. */
+    rc = subjournalPageIfRequired(pPg); 
+    if( rc==SQLITE_OK ){
+      rc = pagerWalFrames(pPager, pPg, 0, 0);
+    }
+  }else{
+  
+    /* Sync the journal file if required. */
+    if( pPg->flags&PGHDR_NEED_SYNC 
+     || pPager->eState==PAGER_WRITER_CACHEMOD
+    ){
+      rc = syncJournal(pPager, 1);
+    }
+  
+    /* Write the contents of the page out to the database file. */
+    if( rc==SQLITE_OK ){
+      assert( (pPg->flags&PGHDR_NEED_SYNC)==0 );
+      rc = pager_write_pagelist(pPager, pPg);
+    }
+  }
+
+  /* Mark the page as clean. */
+  if( rc==SQLITE_OK ){
+    PAGERTRACE(("STRESS %d page %d\n", PAGERID(pPager), pPg->pgno));
+    sqlite3PcacheMakeClean(pPg);
+  }
+
+  return pager_error(pPager, rc); 
+}
+
+/*
+** Flush all unreferenced dirty pages to disk.
+*/
+SQLITE_PRIVATE int sqlite3PagerFlush(Pager *pPager){
+  int rc = pPager->errCode;
+  if( !MEMDB ){
+    PgHdr *pList = sqlite3PcacheDirtyList(pPager->pPCache);
+    assert( assert_pager_state(pPager) );
+    while( rc==SQLITE_OK && pList ){
+      PgHdr *pNext = pList->pDirty;
+      if( pList->nRef==0 ){
+        rc = pagerStress((void*)pPager, pList);
+      }
+      pList = pNext;
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Allocate and initialize a new Pager object and put a pointer to it
+** in *ppPager. The pager should eventually be freed by passing it
+** to sqlite3PagerClose().
+**
+** The zFilename argument is the path to the database file to open.
+** If zFilename is NULL then a randomly-named temporary file is created
+** and used as the file to be cached. Temporary files are be deleted
+** automatically when they are closed. If zFilename is ":memory:" then 
+** all information is held in cache. It is never written to disk. 
+** This can be used to implement an in-memory database.
+**
+** The nExtra parameter specifies the number of bytes of space allocated
+** along with each page reference. This space is available to the user
+** via the sqlite3PagerGetExtra() API.
+**
+** The flags argument is used to specify properties that affect the
+** operation of the pager. It should be passed some bitwise combination
+** of the PAGER_* flags.
+**
+** The vfsFlags parameter is a bitmask to pass to the flags parameter
+** of the xOpen() method of the supplied VFS when opening files. 
+**
+** If the pager object is allocated and the specified file opened 
+** successfully, SQLITE_OK is returned and *ppPager set to point to
+** the new pager object. If an error occurs, *ppPager is set to NULL
+** and error code returned. This function may return SQLITE_NOMEM
+** (sqlite3Malloc() is used to allocate memory), SQLITE_CANTOPEN or 
+** various SQLITE_IO_XXX errors.
+*/
+SQLITE_PRIVATE int sqlite3PagerOpen(
+  sqlite3_vfs *pVfs,       /* The virtual file system to use */
+  Pager **ppPager,         /* OUT: Return the Pager structure here */
+  const char *zFilename,   /* Name of the database file to open */
+  int nExtra,              /* Extra bytes append to each in-memory page */
+  int flags,               /* flags controlling this file */
+  int vfsFlags,            /* flags passed through to sqlite3_vfs.xOpen() */
+  void (*xReinit)(DbPage*) /* Function to reinitialize pages */
+){
+  u8 *pPtr;
+  Pager *pPager = 0;       /* Pager object to allocate and return */
+  int rc = SQLITE_OK;      /* Return code */
+  int tempFile = 0;        /* True for temp files (incl. in-memory files) */
+  int memDb = 0;           /* True if this is an in-memory file */
+  int readOnly = 0;        /* True if this is a read-only file */
+  int journalFileSize;     /* Bytes to allocate for each journal fd */
+  char *zPathname = 0;     /* Full path to database file */
+  int nPathname = 0;       /* Number of bytes in zPathname */
+  int useJournal = (flags & PAGER_OMIT_JOURNAL)==0; /* False to omit journal */
+  int pcacheSize = sqlite3PcacheSize();       /* Bytes to allocate for PCache */
+  u32 szPageDflt = SQLITE_DEFAULT_PAGE_SIZE;  /* Default page size */
+  const char *zUri = 0;    /* URI args to copy */
+  int nUri = 0;            /* Number of bytes of URI args at *zUri */
+
+  /* Figure out how much space is required for each journal file-handle
+  ** (there are two of them, the main journal and the sub-journal).  */
+  journalFileSize = ROUND8(sqlite3JournalSize(pVfs));
+
+  /* Set the output variable to NULL in case an error occurs. */
+  *ppPager = 0;
+
+#ifndef SQLITE_OMIT_MEMORYDB
+  if( flags & PAGER_MEMORY ){
+    memDb = 1;
+    if( zFilename && zFilename[0] ){
+      zPathname = sqlite3DbStrDup(0, zFilename);
+      if( zPathname==0  ) return SQLITE_NOMEM_BKPT;
+      nPathname = sqlite3Strlen30(zPathname);
+      zFilename = 0;
+    }
+  }
+#endif
+
+  /* Compute and store the full pathname in an allocated buffer pointed
+  ** to by zPathname, length nPathname. Or, if this is a temporary file,
+  ** leave both nPathname and zPathname set to 0.
+  */
+  if( zFilename && zFilename[0] ){
+    const char *z;
+    nPathname = pVfs->mxPathname+1;
+    zPathname = sqlite3DbMallocRaw(0, nPathname*2);
+    if( zPathname==0 ){
+      return SQLITE_NOMEM_BKPT;
+    }
+    zPathname[0] = 0; /* Make sure initialized even if FullPathname() fails */
+    rc = sqlite3OsFullPathname(pVfs, zFilename, nPathname, zPathname);
+    nPathname = sqlite3Strlen30(zPathname);
+    z = zUri = &zFilename[sqlite3Strlen30(zFilename)+1];
+    while( *z ){
+      z += sqlite3Strlen30(z)+1;
+      z += sqlite3Strlen30(z)+1;
+    }
+    nUri = (int)(&z[1] - zUri);
+    assert( nUri>=0 );
+    if( rc==SQLITE_OK && nPathname+8>pVfs->mxPathname ){
+      /* This branch is taken when the journal path required by
+      ** the database being opened will be more than pVfs->mxPathname
+      ** bytes in length. This means the database cannot be opened,
+      ** as it will not be possible to open the journal file or even
+      ** check for a hot-journal before reading.
+      */
+      rc = SQLITE_CANTOPEN_BKPT;
+    }
+    if( rc!=SQLITE_OK ){
+      sqlite3DbFree(0, zPathname);
+      return rc;
+    }
+  }
+
+  /* Allocate memory for the Pager structure, PCache object, the
+  ** three file descriptors, the database file name and the journal 
+  ** file name. The layout in memory is as follows:
+  **
+  **     Pager object                    (sizeof(Pager) bytes)
+  **     PCache object                   (sqlite3PcacheSize() bytes)
+  **     Database file handle            (pVfs->szOsFile bytes)
+  **     Sub-journal file handle         (journalFileSize bytes)
+  **     Main journal file handle        (journalFileSize bytes)
+  **     Database file name              (nPathname+1 bytes)
+  **     Journal file name               (nPathname+8+1 bytes)
+  */
+  pPtr = (u8 *)sqlite3MallocZero(
+    ROUND8(sizeof(*pPager)) +      /* Pager structure */
+    ROUND8(pcacheSize) +           /* PCache object */
+    ROUND8(pVfs->szOsFile) +       /* The main db file */
+    journalFileSize * 2 +          /* The two journal files */ 
+    nPathname + 1 + nUri +         /* zFilename */
+    nPathname + 8 + 2              /* zJournal */
+#ifndef SQLITE_OMIT_WAL
+    + nPathname + 4 + 2            /* zWal */
+#endif
+  );
+  assert( EIGHT_BYTE_ALIGNMENT(SQLITE_INT_TO_PTR(journalFileSize)) );
+  if( !pPtr ){
+    sqlite3DbFree(0, zPathname);
+    return SQLITE_NOMEM_BKPT;
+  }
+  pPager =              (Pager*)(pPtr);
+  pPager->pPCache =    (PCache*)(pPtr += ROUND8(sizeof(*pPager)));
+  pPager->fd =   (sqlite3_file*)(pPtr += ROUND8(pcacheSize));
+  pPager->sjfd = (sqlite3_file*)(pPtr += ROUND8(pVfs->szOsFile));
+  pPager->jfd =  (sqlite3_file*)(pPtr += journalFileSize);
+  pPager->zFilename =    (char*)(pPtr += journalFileSize);
+  assert( EIGHT_BYTE_ALIGNMENT(pPager->jfd) );
+
+  /* Fill in the Pager.zFilename and Pager.zJournal buffers, if required. */
+  if( zPathname ){
+    assert( nPathname>0 );
+    pPager->zJournal =   (char*)(pPtr += nPathname + 1 + nUri);
+    memcpy(pPager->zFilename, zPathname, nPathname);
+    if( nUri ) memcpy(&pPager->zFilename[nPathname+1], zUri, nUri);
+    memcpy(pPager->zJournal, zPathname, nPathname);
+    memcpy(&pPager->zJournal[nPathname], "-journal\000", 8+2);
+    sqlite3FileSuffix3(pPager->zFilename, pPager->zJournal);
+#ifndef SQLITE_OMIT_WAL
+    pPager->zWal = &pPager->zJournal[nPathname+8+1];
+    memcpy(pPager->zWal, zPathname, nPathname);
+    memcpy(&pPager->zWal[nPathname], "-wal\000", 4+1);
+    sqlite3FileSuffix3(pPager->zFilename, pPager->zWal);
+#endif
+    sqlite3DbFree(0, zPathname);
+  }
+  pPager->pVfs = pVfs;
+  pPager->vfsFlags = vfsFlags;
+
+  /* Open the pager file.
+  */
+  if( zFilename && zFilename[0] ){
+    int fout = 0;                    /* VFS flags returned by xOpen() */
+    rc = sqlite3OsOpen(pVfs, pPager->zFilename, pPager->fd, vfsFlags, &fout);
+    assert( !memDb );
+    readOnly = (fout&SQLITE_OPEN_READONLY);
+
+    /* If the file was successfully opened for read/write access,
+    ** choose a default page size in case we have to create the
+    ** database file. The default page size is the maximum of:
+    **
+    **    + SQLITE_DEFAULT_PAGE_SIZE,
+    **    + The value returned by sqlite3OsSectorSize()
+    **    + The largest page size that can be written atomically.
+    */
+    if( rc==SQLITE_OK ){
+      int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
+      if( !readOnly ){
+        setSectorSize(pPager);
+        assert(SQLITE_DEFAULT_PAGE_SIZE<=SQLITE_MAX_DEFAULT_PAGE_SIZE);
+        if( szPageDflt<pPager->sectorSize ){
+          if( pPager->sectorSize>SQLITE_MAX_DEFAULT_PAGE_SIZE ){
+            szPageDflt = SQLITE_MAX_DEFAULT_PAGE_SIZE;
+          }else{
+            szPageDflt = (u32)pPager->sectorSize;
+          }
+        }
+#ifdef SQLITE_ENABLE_ATOMIC_WRITE
+        {
+          int ii;
+          assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
+          assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));
+          assert(SQLITE_MAX_DEFAULT_PAGE_SIZE<=65536);
+          for(ii=szPageDflt; ii<=SQLITE_MAX_DEFAULT_PAGE_SIZE; ii=ii*2){
+            if( iDc&(SQLITE_IOCAP_ATOMIC|(ii>>8)) ){
+              szPageDflt = ii;
+            }
+          }
+        }
+#endif
+      }
+      pPager->noLock = sqlite3_uri_boolean(zFilename, "nolock", 0);
+      if( (iDc & SQLITE_IOCAP_IMMUTABLE)!=0
+       || sqlite3_uri_boolean(zFilename, "immutable", 0) ){
+          vfsFlags |= SQLITE_OPEN_READONLY;
+          goto act_like_temp_file;
+      }
+    }
+  }else{
+    /* If a temporary file is requested, it is not opened immediately.
+    ** In this case we accept the default page size and delay actually
+    ** opening the file until the first call to OsWrite().
+    **
+    ** This branch is also run for an in-memory database. An in-memory
+    ** database is the same as a temp-file that is never written out to
+    ** disk and uses an in-memory rollback journal.
+    **
+    ** This branch also runs for files marked as immutable.
+    */ 
+act_like_temp_file:
+    tempFile = 1;
+    pPager->eState = PAGER_READER;     /* Pretend we already have a lock */
+    pPager->eLock = EXCLUSIVE_LOCK;    /* Pretend we are in EXCLUSIVE mode */
+    pPager->noLock = 1;                /* Do no locking */
+    readOnly = (vfsFlags&SQLITE_OPEN_READONLY);
+  }
+
+  /* The following call to PagerSetPagesize() serves to set the value of 
+  ** Pager.pageSize and to allocate the Pager.pTmpSpace buffer.
+  */
+  if( rc==SQLITE_OK ){
+    assert( pPager->memDb==0 );
+    rc = sqlite3PagerSetPagesize(pPager, &szPageDflt, -1);
+    testcase( rc!=SQLITE_OK );
+  }
+
+  /* Initialize the PCache object. */
+  if( rc==SQLITE_OK ){
+    assert( nExtra<1000 );
+    nExtra = ROUND8(nExtra);
+    rc = sqlite3PcacheOpen(szPageDflt, nExtra, !memDb,
+                       !memDb?pagerStress:0, (void *)pPager, pPager->pPCache);
+  }
+
+  /* If an error occurred above, free the  Pager structure and close the file.
+  */
+  if( rc!=SQLITE_OK ){
+    sqlite3OsClose(pPager->fd);
+    sqlite3PageFree(pPager->pTmpSpace);
+    sqlite3_free(pPager);
+    return rc;
+  }
+
+  PAGERTRACE(("OPEN %d %s\n", FILEHANDLEID(pPager->fd), pPager->zFilename));
+  IOTRACE(("OPEN %p %s\n", pPager, pPager->zFilename))
+
+  pPager->useJournal = (u8)useJournal;
+  /* pPager->stmtOpen = 0; */
+  /* pPager->stmtInUse = 0; */
+  /* pPager->nRef = 0; */
+  /* pPager->stmtSize = 0; */
+  /* pPager->stmtJSize = 0; */
+  /* pPager->nPage = 0; */
+  pPager->mxPgno = SQLITE_MAX_PAGE_COUNT;
+  /* pPager->state = PAGER_UNLOCK; */
+  /* pPager->errMask = 0; */
+  pPager->tempFile = (u8)tempFile;
+  assert( tempFile==PAGER_LOCKINGMODE_NORMAL 
+          || tempFile==PAGER_LOCKINGMODE_EXCLUSIVE );
+  assert( PAGER_LOCKINGMODE_EXCLUSIVE==1 );
+  pPager->exclusiveMode = (u8)tempFile; 
+  pPager->changeCountDone = pPager->tempFile;
+  pPager->memDb = (u8)memDb;
+  pPager->readOnly = (u8)readOnly;
+  assert( useJournal || pPager->tempFile );
+  pPager->noSync = pPager->tempFile;
+  if( pPager->noSync ){
+    assert( pPager->fullSync==0 );
+    assert( pPager->extraSync==0 );
+    assert( pPager->syncFlags==0 );
+    assert( pPager->walSyncFlags==0 );
+    assert( pPager->ckptSyncFlags==0 );
+  }else{
+    pPager->fullSync = 1;
+    pPager->extraSync = 0;
+    pPager->syncFlags = SQLITE_SYNC_NORMAL;
+    pPager->walSyncFlags = SQLITE_SYNC_NORMAL | WAL_SYNC_TRANSACTIONS;
+    pPager->ckptSyncFlags = SQLITE_SYNC_NORMAL;
+  }
+  /* pPager->pFirst = 0; */
+  /* pPager->pFirstSynced = 0; */
+  /* pPager->pLast = 0; */
+  pPager->nExtra = (u16)nExtra;
+  pPager->journalSizeLimit = SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT;
+  assert( isOpen(pPager->fd) || tempFile );
+  setSectorSize(pPager);
+  if( !useJournal ){
+    pPager->journalMode = PAGER_JOURNALMODE_OFF;
+  }else if( memDb ){
+    pPager->journalMode = PAGER_JOURNALMODE_MEMORY;
+  }
+  /* pPager->xBusyHandler = 0; */
+  /* pPager->pBusyHandlerArg = 0; */
+  pPager->xReiniter = xReinit;
+  /* memset(pPager->aHash, 0, sizeof(pPager->aHash)); */
+  /* pPager->szMmap = SQLITE_DEFAULT_MMAP_SIZE // will be set by btree.c */
+
+  *ppPager = pPager;
+  return SQLITE_OK;
+}
+
+
+/* Verify that the database file has not be deleted or renamed out from
+** under the pager.  Return SQLITE_OK if the database is still were it ought
+** to be on disk.  Return non-zero (SQLITE_READONLY_DBMOVED or some other error
+** code from sqlite3OsAccess()) if the database has gone missing.
+*/
+static int databaseIsUnmoved(Pager *pPager){
+  int bHasMoved = 0;
+  int rc;
+
+  if( pPager->tempFile ) return SQLITE_OK;
+  if( pPager->dbSize==0 ) return SQLITE_OK;
+  assert( pPager->zFilename && pPager->zFilename[0] );
+  rc = sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_HAS_MOVED, &bHasMoved);
+  if( rc==SQLITE_NOTFOUND ){
+    /* If the HAS_MOVED file-control is unimplemented, assume that the file
+    ** has not been moved.  That is the historical behavior of SQLite: prior to
+    ** version 3.8.3, it never checked */
+    rc = SQLITE_OK;
+  }else if( rc==SQLITE_OK && bHasMoved ){
+    rc = SQLITE_READONLY_DBMOVED;
+  }
+  return rc;
+}
+
+
+/*
+** This function is called after transitioning from PAGER_UNLOCK to
+** PAGER_SHARED state. It tests if there is a hot journal present in
+** the file-system for the given pager. A hot journal is one that 
+** needs to be played back. According to this function, a hot-journal
+** file exists if the following criteria are met:
+**
+**   * The journal file exists in the file system, and
+**   * No process holds a RESERVED or greater lock on the database file, and
+**   * The database file itself is greater than 0 bytes in size, and
+**   * The first byte of the journal file exists and is not 0x00.
+**
+** If the current size of the database file is 0 but a journal file
+** exists, that is probably an old journal left over from a prior
+** database with the same name. In this case the journal file is
+** just deleted using OsDelete, *pExists is set to 0 and SQLITE_OK
+** is returned.
+**
+** This routine does not check if there is a master journal filename
+** at the end of the file. If there is, and that master journal file
+** does not exist, then the journal file is not really hot. In this
+** case this routine will return a false-positive. The pager_playback()
+** routine will discover that the journal file is not really hot and 
+** will not roll it back. 
+**
+** If a hot-journal file is found to exist, *pExists is set to 1 and 
+** SQLITE_OK returned. If no hot-journal file is present, *pExists is
+** set to 0 and SQLITE_OK returned. If an IO error occurs while trying
+** to determine whether or not a hot-journal file exists, the IO error
+** code is returned and the value of *pExists is undefined.
+*/
+static int hasHotJournal(Pager *pPager, int *pExists){
+  sqlite3_vfs * const pVfs = pPager->pVfs;
+  int rc = SQLITE_OK;           /* Return code */
+  int exists = 1;               /* True if a journal file is present */
+  int jrnlOpen = !!isOpen(pPager->jfd);
+
+  assert( pPager->useJournal );
+  assert( isOpen(pPager->fd) );
+  assert( pPager->eState==PAGER_OPEN );
+
+  assert( jrnlOpen==0 || ( sqlite3OsDeviceCharacteristics(pPager->jfd) &
+    SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
+  ));
+
+  *pExists = 0;
+  if( !jrnlOpen ){
+    rc = sqlite3OsAccess(pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &exists);
+  }
+  if( rc==SQLITE_OK && exists ){
+    int locked = 0;             /* True if some process holds a RESERVED lock */
+
+    /* Race condition here:  Another process might have been holding the
+    ** the RESERVED lock and have a journal open at the sqlite3OsAccess() 
+    ** call above, but then delete the journal and drop the lock before
+    ** we get to the following sqlite3OsCheckReservedLock() call.  If that
+    ** is the case, this routine might think there is a hot journal when
+    ** in fact there is none.  This results in a false-positive which will
+    ** be dealt with by the playback routine.  Ticket #3883.
+    */
+    rc = sqlite3OsCheckReservedLock(pPager->fd, &locked);
+    if( rc==SQLITE_OK && !locked ){
+      Pgno nPage;                 /* Number of pages in database file */
+
+      assert( pPager->tempFile==0 );
+      rc = pagerPagecount(pPager, &nPage);
+      if( rc==SQLITE_OK ){
+        /* If the database is zero pages in size, that means that either (1) the
+        ** journal is a remnant from a prior database with the same name where
+        ** the database file but not the journal was deleted, or (2) the initial
+        ** transaction that populates a new database is being rolled back.
+        ** In either case, the journal file can be deleted.  However, take care
+        ** not to delete the journal file if it is already open due to
+        ** journal_mode=PERSIST.
+        */
+        if( nPage==0 && !jrnlOpen ){
+          sqlite3BeginBenignMalloc();
+          if( pagerLockDb(pPager, RESERVED_LOCK)==SQLITE_OK ){
+            sqlite3OsDelete(pVfs, pPager->zJournal, 0);
+            if( !pPager->exclusiveMode ) pagerUnlockDb(pPager, SHARED_LOCK);
+          }
+          sqlite3EndBenignMalloc();
+        }else{
+          /* The journal file exists and no other connection has a reserved
+          ** or greater lock on the database file. Now check that there is
+          ** at least one non-zero bytes at the start of the journal file.
+          ** If there is, then we consider this journal to be hot. If not, 
+          ** it can be ignored.
+          */
+          if( !jrnlOpen ){
+            int f = SQLITE_OPEN_READONLY|SQLITE_OPEN_MAIN_JOURNAL;
+            rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, f, &f);
+          }
+          if( rc==SQLITE_OK ){
+            u8 first = 0;
+            rc = sqlite3OsRead(pPager->jfd, (void *)&first, 1, 0);
+            if( rc==SQLITE_IOERR_SHORT_READ ){
+              rc = SQLITE_OK;
+            }
+            if( !jrnlOpen ){
+              sqlite3OsClose(pPager->jfd);
+            }
+            *pExists = (first!=0);
+          }else if( rc==SQLITE_CANTOPEN ){
+            /* If we cannot open the rollback journal file in order to see if
+            ** it has a zero header, that might be due to an I/O error, or
+            ** it might be due to the race condition described above and in
+            ** ticket #3883.  Either way, assume that the journal is hot.
+            ** This might be a false positive.  But if it is, then the
+            ** automatic journal playback and recovery mechanism will deal
+            ** with it under an EXCLUSIVE lock where we do not need to
+            ** worry so much with race conditions.
+            */
+            *pExists = 1;
+            rc = SQLITE_OK;
+          }
+        }
+      }
+    }
+  }
+
+  return rc;
+}
+
+/*
+** This function is called to obtain a shared lock on the database file.
+** It is illegal to call sqlite3PagerGet() until after this function
+** has been successfully called. If a shared-lock is already held when
+** this function is called, it is a no-op.
+**
+** The following operations are also performed by this function.
+**
+**   1) If the pager is currently in PAGER_OPEN state (no lock held
+**      on the database file), then an attempt is made to obtain a
+**      SHARED lock on the database file. Immediately after obtaining
+**      the SHARED lock, the file-system is checked for a hot-journal,
+**      which is played back if present. Following any hot-journal 
+**      rollback, the contents of the cache are validated by checking
+**      the 'change-counter' field of the database file header and
+**      discarded if they are found to be invalid.
+**
+**   2) If the pager is running in exclusive-mode, and there are currently
+**      no outstanding references to any pages, and is in the error state,
+**      then an attempt is made to clear the error state by discarding
+**      the contents of the page cache and rolling back any open journal
+**      file.
+**
+** If everything is successful, SQLITE_OK is returned. If an IO error 
+** occurs while locking the database, checking for a hot-journal file or 
+** rolling back a journal file, the IO error code is returned.
+*/
+SQLITE_PRIVATE int sqlite3PagerSharedLock(Pager *pPager){
+  int rc = SQLITE_OK;                /* Return code */
+
+  /* This routine is only called from b-tree and only when there are no
+  ** outstanding pages. This implies that the pager state should either
+  ** be OPEN or READER. READER is only possible if the pager is or was in 
+  ** exclusive access mode.  */
+  assert( sqlite3PcacheRefCount(pPager->pPCache)==0 );
+  assert( assert_pager_state(pPager) );
+  assert( pPager->eState==PAGER_OPEN || pPager->eState==PAGER_READER );
+  assert( pPager->errCode==SQLITE_OK );
+
+  if( !pagerUseWal(pPager) && pPager->eState==PAGER_OPEN ){
+    int bHotJournal = 1;          /* True if there exists a hot journal-file */
+
+    assert( !MEMDB );
+    assert( pPager->tempFile==0 || pPager->eLock==EXCLUSIVE_LOCK );
+
+    rc = pager_wait_on_lock(pPager, SHARED_LOCK);
+    if( rc!=SQLITE_OK ){
+      assert( pPager->eLock==NO_LOCK || pPager->eLock==UNKNOWN_LOCK );
+      goto failed;
+    }
+
+    /* If a journal file exists, and there is no RESERVED lock on the
+    ** database file, then it either needs to be played back or deleted.
+    */
+    if( pPager->eLock<=SHARED_LOCK ){
+      rc = hasHotJournal(pPager, &bHotJournal);
+    }
+    if( rc!=SQLITE_OK ){
+      goto failed;
+    }
+    if( bHotJournal ){
+      if( pPager->readOnly ){
+        rc = SQLITE_READONLY_ROLLBACK;
+        goto failed;
+      }
+
+      /* Get an EXCLUSIVE lock on the database file. At this point it is
+      ** important that a RESERVED lock is not obtained on the way to the
+      ** EXCLUSIVE lock. If it were, another process might open the
+      ** database file, detect the RESERVED lock, and conclude that the
+      ** database is safe to read while this process is still rolling the 
+      ** hot-journal back.
+      ** 
+      ** Because the intermediate RESERVED lock is not requested, any
+      ** other process attempting to access the database file will get to 
+      ** this point in the code and fail to obtain its own EXCLUSIVE lock 
+      ** on the database file.
+      **
+      ** Unless the pager is in locking_mode=exclusive mode, the lock is
+      ** downgraded to SHARED_LOCK before this function returns.
+      */
+      rc = pagerLockDb(pPager, EXCLUSIVE_LOCK);
+      if( rc!=SQLITE_OK ){
+        goto failed;
+      }
+ 
+      /* If it is not already open and the file exists on disk, open the 
+      ** journal for read/write access. Write access is required because 
+      ** in exclusive-access mode the file descriptor will be kept open 
+      ** and possibly used for a transaction later on. Also, write-access 
+      ** is usually required to finalize the journal in journal_mode=persist 
+      ** mode (and also for journal_mode=truncate on some systems).
+      **
+      ** If the journal does not exist, it usually means that some 
+      ** other connection managed to get in and roll it back before 
+      ** this connection obtained the exclusive lock above. Or, it 
+      ** may mean that the pager was in the error-state when this
+      ** function was called and the journal file does not exist.
+      */
+      if( !isOpen(pPager->jfd) ){
+        sqlite3_vfs * const pVfs = pPager->pVfs;
+        int bExists;              /* True if journal file exists */
+        rc = sqlite3OsAccess(
+            pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &bExists);
+        if( rc==SQLITE_OK && bExists ){
+          int fout = 0;
+          int f = SQLITE_OPEN_READWRITE|SQLITE_OPEN_MAIN_JOURNAL;
+          assert( !pPager->tempFile );
+          rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, f, &fout);
+          assert( rc!=SQLITE_OK || isOpen(pPager->jfd) );
+          if( rc==SQLITE_OK && fout&SQLITE_OPEN_READONLY ){
+            rc = SQLITE_CANTOPEN_BKPT;
+            sqlite3OsClose(pPager->jfd);
+          }
+        }
+      }
+ 
+      /* Playback and delete the journal.  Drop the database write
+      ** lock and reacquire the read lock. Purge the cache before
+      ** playing back the hot-journal so that we don't end up with
+      ** an inconsistent cache.  Sync the hot journal before playing
+      ** it back since the process that crashed and left the hot journal
+      ** probably did not sync it and we are required to always sync
+      ** the journal before playing it back.
+      */
+      if( isOpen(pPager->jfd) ){
+        assert( rc==SQLITE_OK );
+        rc = pagerSyncHotJournal(pPager);
+        if( rc==SQLITE_OK ){
+          rc = pager_playback(pPager, !pPager->tempFile);
+          pPager->eState = PAGER_OPEN;
+        }
+      }else if( !pPager->exclusiveMode ){
+        pagerUnlockDb(pPager, SHARED_LOCK);
+      }
+
+      if( rc!=SQLITE_OK ){
+        /* This branch is taken if an error occurs while trying to open
+        ** or roll back a hot-journal while holding an EXCLUSIVE lock. The
+        ** pager_unlock() routine will be called before returning to unlock
+        ** the file. If the unlock attempt fails, then Pager.eLock must be
+        ** set to UNKNOWN_LOCK (see the comment above the #define for 
+        ** UNKNOWN_LOCK above for an explanation). 
+        **
+        ** In order to get pager_unlock() to do this, set Pager.eState to
+        ** PAGER_ERROR now. This is not actually counted as a transition
+        ** to ERROR state in the state diagram at the top of this file,
+        ** since we know that the same call to pager_unlock() will very
+        ** shortly transition the pager object to the OPEN state. Calling
+        ** assert_pager_state() would fail now, as it should not be possible
+        ** to be in ERROR state when there are zero outstanding page 
+        ** references.
+        */
+        pager_error(pPager, rc);
+        goto failed;
+      }
+
+      assert( pPager->eState==PAGER_OPEN );
+      assert( (pPager->eLock==SHARED_LOCK)
+           || (pPager->exclusiveMode && pPager->eLock>SHARED_LOCK)
+      );
+    }
+
+    if( !pPager->tempFile && pPager->hasHeldSharedLock ){
+      /* The shared-lock has just been acquired then check to
+      ** see if the database has been modified.  If the database has changed,
+      ** flush the cache.  The hasHeldSharedLock flag prevents this from
+      ** occurring on the very first access to a file, in order to save a
+      ** single unnecessary sqlite3OsRead() call at the start-up.
+      **
+      ** Database changes are detected by looking at 15 bytes beginning
+      ** at offset 24 into the file.  The first 4 of these 16 bytes are
+      ** a 32-bit counter that is incremented with each change.  The
+      ** other bytes change randomly with each file change when
+      ** a codec is in use.
+      ** 
+      ** There is a vanishingly small chance that a change will not be 
+      ** detected.  The chance of an undetected change is so small that
+      ** it can be neglected.
+      */
+      Pgno nPage = 0;
+      char dbFileVers[sizeof(pPager->dbFileVers)];
+
+      rc = pagerPagecount(pPager, &nPage);
+      if( rc ) goto failed;
+
+      if( nPage>0 ){
+        IOTRACE(("CKVERS %p %d\n", pPager, sizeof(dbFileVers)));
+        rc = sqlite3OsRead(pPager->fd, &dbFileVers, sizeof(dbFileVers), 24);
+        if( rc!=SQLITE_OK && rc!=SQLITE_IOERR_SHORT_READ ){
+          goto failed;
+        }
+      }else{
+        memset(dbFileVers, 0, sizeof(dbFileVers));
+      }
+
+      if( memcmp(pPager->dbFileVers, dbFileVers, sizeof(dbFileVers))!=0 ){
+        pager_reset(pPager);
+
+        /* Unmap the database file. It is possible that external processes
+        ** may have truncated the database file and then extended it back
+        ** to its original size while this process was not holding a lock.
+        ** In this case there may exist a Pager.pMap mapping that appears
+        ** to be the right size but is not actually valid. Avoid this
+        ** possibility by unmapping the db here. */
+        if( USEFETCH(pPager) ){
+          sqlite3OsUnfetch(pPager->fd, 0, 0);
+        }
+      }
+    }
+
+    /* If there is a WAL file in the file-system, open this database in WAL
+    ** mode. Otherwise, the following function call is a no-op.
+    */
+    rc = pagerOpenWalIfPresent(pPager);
+#ifndef SQLITE_OMIT_WAL
+    assert( pPager->pWal==0 || rc==SQLITE_OK );
+#endif
+  }
+
+  if( pagerUseWal(pPager) ){
+    assert( rc==SQLITE_OK );
+    rc = pagerBeginReadTransaction(pPager);
+  }
+
+  if( pPager->tempFile==0 && pPager->eState==PAGER_OPEN && rc==SQLITE_OK ){
+    rc = pagerPagecount(pPager, &pPager->dbSize);
+  }
+
+ failed:
+  if( rc!=SQLITE_OK ){
+    assert( !MEMDB );
+    pager_unlock(pPager);
+    assert( pPager->eState==PAGER_OPEN );
+  }else{
+    pPager->eState = PAGER_READER;
+    pPager->hasHeldSharedLock = 1;
+  }
+  return rc;
+}
+
+/*
+** If the reference count has reached zero, rollback any active
+** transaction and unlock the pager.
+**
+** Except, in locking_mode=EXCLUSIVE when there is nothing to in
+** the rollback journal, the unlock is not performed and there is
+** nothing to rollback, so this routine is a no-op.
+*/ 
+static void pagerUnlockIfUnused(Pager *pPager){
+  if( pPager->nMmapOut==0 && (sqlite3PcacheRefCount(pPager->pPCache)==0) ){
+    pagerUnlockAndRollback(pPager);
+  }
+}
+
+/*
+** Acquire a reference to page number pgno in pager pPager (a page
+** reference has type DbPage*). If the requested reference is 
+** successfully obtained, it is copied to *ppPage and SQLITE_OK returned.
+**
+** If the requested page is already in the cache, it is returned. 
+** Otherwise, a new page object is allocated and populated with data
+** read from the database file. In some cases, the pcache module may
+** choose not to allocate a new page object and may reuse an existing
+** object with no outstanding references.
+**
+** The extra data appended to a page is always initialized to zeros the 
+** first time a page is loaded into memory. If the page requested is 
+** already in the cache when this function is called, then the extra
+** data is left as it was when the page object was last used.
+**
+** If the database image is smaller than the requested page or if a 
+** non-zero value is passed as the noContent parameter and the 
+** requested page is not already stored in the cache, then no 
+** actual disk read occurs. In this case the memory image of the 
+** page is initialized to all zeros. 
+**
+** If noContent is true, it means that we do not care about the contents
+** of the page. This occurs in two scenarios:
+**
+**   a) When reading a free-list leaf page from the database, and
+**
+**   b) When a savepoint is being rolled back and we need to load
+**      a new page into the cache to be filled with the data read
+**      from the savepoint journal.
+**
+** If noContent is true, then the data returned is zeroed instead of
+** being read from the database. Additionally, the bits corresponding
+** to pgno in Pager.pInJournal (bitvec of pages already written to the
+** journal file) and the PagerSavepoint.pInSavepoint bitvecs of any open
+** savepoints are set. This means if the page is made writable at any
+** point in the future, using a call to sqlite3PagerWrite(), its contents
+** will not be journaled. This saves IO.
+**
+** The acquisition might fail for several reasons.  In all cases,
+** an appropriate error code is returned and *ppPage is set to NULL.
+**
+** See also sqlite3PagerLookup().  Both this routine and Lookup() attempt
+** to find a page in the in-memory cache first.  If the page is not already
+** in memory, this routine goes to disk to read it in whereas Lookup()
+** just returns 0.  This routine acquires a read-lock the first time it
+** has to go to disk, and could also playback an old journal if necessary.
+** Since Lookup() never goes to disk, it never has to deal with locks
+** or journal files.
+*/
+SQLITE_PRIVATE int sqlite3PagerGet(
+  Pager *pPager,      /* The pager open on the database file */
+  Pgno pgno,          /* Page number to fetch */
+  DbPage **ppPage,    /* Write a pointer to the page here */
+  int flags           /* PAGER_GET_XXX flags */
+){
+  int rc = SQLITE_OK;
+  PgHdr *pPg = 0;
+  u32 iFrame = 0;                 /* Frame to read from WAL file */
+  const int noContent = (flags & PAGER_GET_NOCONTENT);
+
+  /* It is acceptable to use a read-only (mmap) page for any page except
+  ** page 1 if there is no write-transaction open or the ACQUIRE_READONLY
+  ** flag was specified by the caller. And so long as the db is not a 
+  ** temporary or in-memory database.  */
+  const int bMmapOk = (pgno>1 && USEFETCH(pPager)
+   && (pPager->eState==PAGER_READER || (flags & PAGER_GET_READONLY))
+#ifdef SQLITE_HAS_CODEC
+   && pPager->xCodec==0
+#endif
+  );
+
+  /* Optimization note:  Adding the "pgno<=1" term before "pgno==0" here
+  ** allows the compiler optimizer to reuse the results of the "pgno>1"
+  ** test in the previous statement, and avoid testing pgno==0 in the
+  ** common case where pgno is large. */
+  if( pgno<=1 && pgno==0 ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+  assert( pPager->eState>=PAGER_READER );
+  assert( assert_pager_state(pPager) );
+  assert( noContent==0 || bMmapOk==0 );
+
+  assert( pPager->hasHeldSharedLock==1 );
+
+  /* If the pager is in the error state, return an error immediately. 
+  ** Otherwise, request the page from the PCache layer. */
+  if( pPager->errCode!=SQLITE_OK ){
+    rc = pPager->errCode;
+  }else{
+    if( bMmapOk && pagerUseWal(pPager) ){
+      rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iFrame);
+      if( rc!=SQLITE_OK ) goto pager_acquire_err;
+    }
+
+    if( bMmapOk && iFrame==0 ){
+      void *pData = 0;
+
+      rc = sqlite3OsFetch(pPager->fd, 
+          (i64)(pgno-1) * pPager->pageSize, pPager->pageSize, &pData
+      );
+
+      if( rc==SQLITE_OK && pData ){
+        if( pPager->eState>PAGER_READER || pPager->tempFile ){
+          pPg = sqlite3PagerLookup(pPager, pgno);
+        }
+        if( pPg==0 ){
+          rc = pagerAcquireMapPage(pPager, pgno, pData, &pPg);
+        }else{
+          sqlite3OsUnfetch(pPager->fd, (i64)(pgno-1)*pPager->pageSize, pData);
+        }
+        if( pPg ){
+          assert( rc==SQLITE_OK );
+          *ppPage = pPg;
+          return SQLITE_OK;
+        }
+      }
+      if( rc!=SQLITE_OK ){
+        goto pager_acquire_err;
+      }
+    }
+
+    {
+      sqlite3_pcache_page *pBase;
+      pBase = sqlite3PcacheFetch(pPager->pPCache, pgno, 3);
+      if( pBase==0 ){
+        rc = sqlite3PcacheFetchStress(pPager->pPCache, pgno, &pBase);
+        if( rc!=SQLITE_OK ) goto pager_acquire_err;
+        if( pBase==0 ){
+          pPg = *ppPage = 0;
+          rc = SQLITE_NOMEM_BKPT;
+          goto pager_acquire_err;
+        }
+      }
+      pPg = *ppPage = sqlite3PcacheFetchFinish(pPager->pPCache, pgno, pBase);
+      assert( pPg!=0 );
+    }
+  }
+
+  if( rc!=SQLITE_OK ){
+    /* Either the call to sqlite3PcacheFetch() returned an error or the
+    ** pager was already in the error-state when this function was called.
+    ** Set pPg to 0 and jump to the exception handler.  */
+    pPg = 0;
+    goto pager_acquire_err;
+  }
+  assert( pPg==(*ppPage) );
+  assert( pPg->pgno==pgno );
+  assert( pPg->pPager==pPager || pPg->pPager==0 );
+
+  if( pPg->pPager && !noContent ){
+    /* In this case the pcache already contains an initialized copy of
+    ** the page. Return without further ado.  */
+    assert( pgno<=PAGER_MAX_PGNO && pgno!=PAGER_MJ_PGNO(pPager) );
+    pPager->aStat[PAGER_STAT_HIT]++;
+    return SQLITE_OK;
+
+  }else{
+    /* The pager cache has created a new page. Its content needs to 
+    ** be initialized.  */
+
+    pPg->pPager = pPager;
+
+    /* The maximum page number is 2^31. Return SQLITE_CORRUPT if a page
+    ** number greater than this, or the unused locking-page, is requested. */
+    if( pgno>PAGER_MAX_PGNO || pgno==PAGER_MJ_PGNO(pPager) ){
+      rc = SQLITE_CORRUPT_BKPT;
+      goto pager_acquire_err;
+    }
+
+    assert( !isOpen(pPager->fd) || !MEMDB );
+    if( !isOpen(pPager->fd) || pPager->dbSize<pgno || noContent ){
+      if( pgno>pPager->mxPgno ){
+        rc = SQLITE_FULL;
+        goto pager_acquire_err;
+      }
+      if( noContent ){
+        /* Failure to set the bits in the InJournal bit-vectors is benign.
+        ** It merely means that we might do some extra work to journal a 
+        ** page that does not need to be journaled.  Nevertheless, be sure 
+        ** to test the case where a malloc error occurs while trying to set 
+        ** a bit in a bit vector.
+        */
+        sqlite3BeginBenignMalloc();
+        if( pgno<=pPager->dbOrigSize ){
+          TESTONLY( rc = ) sqlite3BitvecSet(pPager->pInJournal, pgno);
+          testcase( rc==SQLITE_NOMEM );
+        }
+        TESTONLY( rc = ) addToSavepointBitvecs(pPager, pgno);
+        testcase( rc==SQLITE_NOMEM );
+        sqlite3EndBenignMalloc();
+      }
+      memset(pPg->pData, 0, pPager->pageSize);
+      IOTRACE(("ZERO %p %d\n", pPager, pgno));
+    }else{
+      if( pagerUseWal(pPager) && bMmapOk==0 ){
+        rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iFrame);
+        if( rc!=SQLITE_OK ) goto pager_acquire_err;
+      }
+      assert( pPg->pPager==pPager );
+      pPager->aStat[PAGER_STAT_MISS]++;
+      rc = readDbPage(pPg, iFrame);
+      if( rc!=SQLITE_OK ){
+        goto pager_acquire_err;
+      }
+    }
+    pager_set_pagehash(pPg);
+  }
+
+  return SQLITE_OK;
+
+pager_acquire_err:
+  assert( rc!=SQLITE_OK );
+  if( pPg ){
+    sqlite3PcacheDrop(pPg);
+  }
+  pagerUnlockIfUnused(pPager);
+
+  *ppPage = 0;
+  return rc;
+}
+
+/*
+** Acquire a page if it is already in the in-memory cache.  Do
+** not read the page from disk.  Return a pointer to the page,
+** or 0 if the page is not in cache. 
+**
+** See also sqlite3PagerGet().  The difference between this routine
+** and sqlite3PagerGet() is that _get() will go to the disk and read
+** in the page if the page is not already in cache.  This routine
+** returns NULL if the page is not in cache or if a disk I/O error 
+** has ever happened.
+*/
+SQLITE_PRIVATE DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno){
+  sqlite3_pcache_page *pPage;
+  assert( pPager!=0 );
+  assert( pgno!=0 );
+  assert( pPager->pPCache!=0 );
+  pPage = sqlite3PcacheFetch(pPager->pPCache, pgno, 0);
+  assert( pPage==0 || pPager->hasHeldSharedLock );
+  if( pPage==0 ) return 0;
+  return sqlite3PcacheFetchFinish(pPager->pPCache, pgno, pPage);
+}
+
+/*
+** Release a page reference.
+**
+** If the number of references to the page drop to zero, then the
+** page is added to the LRU list.  When all references to all pages
+** are released, a rollback occurs and the lock on the database is
+** removed.
+*/
+SQLITE_PRIVATE void sqlite3PagerUnrefNotNull(DbPage *pPg){
+  Pager *pPager;
+  assert( pPg!=0 );
+  pPager = pPg->pPager;
+  if( pPg->flags & PGHDR_MMAP ){
+    pagerReleaseMapPage(pPg);
+  }else{
+    sqlite3PcacheRelease(pPg);
+  }
+  pagerUnlockIfUnused(pPager);
+}
+SQLITE_PRIVATE void sqlite3PagerUnref(DbPage *pPg){
+  if( pPg ) sqlite3PagerUnrefNotNull(pPg);
+}
+
+/*
+** This function is called at the start of every write transaction.
+** There must already be a RESERVED or EXCLUSIVE lock on the database 
+** file when this routine is called.
+**
+** Open the journal file for pager pPager and write a journal header
+** to the start of it. If there are active savepoints, open the sub-journal
+** as well. This function is only used when the journal file is being 
+** opened to write a rollback log for a transaction. It is not used 
+** when opening a hot journal file to roll it back.
+**
+** If the journal file is already open (as it may be in exclusive mode),
+** then this function just writes a journal header to the start of the
+** already open file. 
+**
+** Whether or not the journal file is opened by this function, the
+** Pager.pInJournal bitvec structure is allocated.
+**
+** Return SQLITE_OK if everything is successful. Otherwise, return 
+** SQLITE_NOMEM if the attempt to allocate Pager.pInJournal fails, or 
+** an IO error code if opening or writing the journal file fails.
+*/
+static int pager_open_journal(Pager *pPager){
+  int rc = SQLITE_OK;                        /* Return code */
+  sqlite3_vfs * const pVfs = pPager->pVfs;   /* Local cache of vfs pointer */
+
+  assert( pPager->eState==PAGER_WRITER_LOCKED );
+  assert( assert_pager_state(pPager) );
+  assert( pPager->pInJournal==0 );
+  
+  /* If already in the error state, this function is a no-op.  But on
+  ** the other hand, this routine is never called if we are already in
+  ** an error state. */
+  if( NEVER(pPager->errCode) ) return pPager->errCode;
+
+  if( !pagerUseWal(pPager) && pPager->journalMode!=PAGER_JOURNALMODE_OFF ){
+    pPager->pInJournal = sqlite3BitvecCreate(pPager->dbSize);
+    if( pPager->pInJournal==0 ){
+      return SQLITE_NOMEM_BKPT;
+    }
+  
+    /* Open the journal file if it is not already open. */
+    if( !isOpen(pPager->jfd) ){
+      if( pPager->journalMode==PAGER_JOURNALMODE_MEMORY ){
+        sqlite3MemJournalOpen(pPager->jfd);
+      }else{
+        int flags = SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE;
+        int nSpill;
+
+        if( pPager->tempFile ){
+          flags |= (SQLITE_OPEN_DELETEONCLOSE|SQLITE_OPEN_TEMP_JOURNAL);
+          nSpill = sqlite3Config.nStmtSpill;
+        }else{
+          flags |= SQLITE_OPEN_MAIN_JOURNAL;
+          nSpill = jrnlBufferSize(pPager);
+        }
+          
+        /* Verify that the database still has the same name as it did when
+        ** it was originally opened. */
+        rc = databaseIsUnmoved(pPager);
+        if( rc==SQLITE_OK ){
+          rc = sqlite3JournalOpen (
+              pVfs, pPager->zJournal, pPager->jfd, flags, nSpill
+          );
+        }
+      }
+      assert( rc!=SQLITE_OK || isOpen(pPager->jfd) );
+    }
+  
+  
+    /* Write the first journal header to the journal file and open 
+    ** the sub-journal if necessary.
+    */
+    if( rc==SQLITE_OK ){
+      /* TODO: Check if all of these are really required. */
+      pPager->nRec = 0;
+      pPager->journalOff = 0;
+      pPager->setMaster = 0;
+      pPager->journalHdr = 0;
+      rc = writeJournalHdr(pPager);
+    }
+  }
+
+  if( rc!=SQLITE_OK ){
+    sqlite3BitvecDestroy(pPager->pInJournal);
+    pPager->pInJournal = 0;
+  }else{
+    assert( pPager->eState==PAGER_WRITER_LOCKED );
+    pPager->eState = PAGER_WRITER_CACHEMOD;
+  }
+
+  return rc;
+}
+
+/*
+** Begin a write-transaction on the specified pager object. If a 
+** write-transaction has already been opened, this function is a no-op.
+**
+** If the exFlag argument is false, then acquire at least a RESERVED
+** lock on the database file. If exFlag is true, then acquire at least
+** an EXCLUSIVE lock. If such a lock is already held, no locking 
+** functions need be called.
+**
+** If the subjInMemory argument is non-zero, then any sub-journal opened
+** within this transaction will be opened as an in-memory file. This
+** has no effect if the sub-journal is already opened (as it may be when
+** running in exclusive mode) or if the transaction does not require a
+** sub-journal. If the subjInMemory argument is zero, then any required
+** sub-journal is implemented in-memory if pPager is an in-memory database, 
+** or using a temporary file otherwise.
+*/
+SQLITE_PRIVATE int sqlite3PagerBegin(Pager *pPager, int exFlag, int subjInMemory){
+  int rc = SQLITE_OK;
+
+  if( pPager->errCode ) return pPager->errCode;
+  assert( pPager->eState>=PAGER_READER && pPager->eState<PAGER_ERROR );
+  pPager->subjInMemory = (u8)subjInMemory;
+
+  if( ALWAYS(pPager->eState==PAGER_READER) ){
+    assert( pPager->pInJournal==0 );
+
+    if( pagerUseWal(pPager) ){
+      /* If the pager is configured to use locking_mode=exclusive, and an
+      ** exclusive lock on the database is not already held, obtain it now.
+      */
+      if( pPager->exclusiveMode && sqlite3WalExclusiveMode(pPager->pWal, -1) ){
+        rc = pagerLockDb(pPager, EXCLUSIVE_LOCK);
+        if( rc!=SQLITE_OK ){
+          return rc;
+        }
+        (void)sqlite3WalExclusiveMode(pPager->pWal, 1);
+      }
+
+      /* Grab the write lock on the log file. If successful, upgrade to
+      ** PAGER_RESERVED state. Otherwise, return an error code to the caller.
+      ** The busy-handler is not invoked if another connection already
+      ** holds the write-lock. If possible, the upper layer will call it.
+      */
+      rc = sqlite3WalBeginWriteTransaction(pPager->pWal);
+    }else{
+      /* Obtain a RESERVED lock on the database file. If the exFlag parameter
+      ** is true, then immediately upgrade this to an EXCLUSIVE lock. The
+      ** busy-handler callback can be used when upgrading to the EXCLUSIVE
+      ** lock, but not when obtaining the RESERVED lock.
+      */
+      rc = pagerLockDb(pPager, RESERVED_LOCK);
+      if( rc==SQLITE_OK && exFlag ){
+        rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
+      }
+    }
+
+    if( rc==SQLITE_OK ){
+      /* Change to WRITER_LOCKED state.
+      **
+      ** WAL mode sets Pager.eState to PAGER_WRITER_LOCKED or CACHEMOD
+      ** when it has an open transaction, but never to DBMOD or FINISHED.
+      ** This is because in those states the code to roll back savepoint 
+      ** transactions may copy data from the sub-journal into the database 
+      ** file as well as into the page cache. Which would be incorrect in 
+      ** WAL mode.
+      */
+      pPager->eState = PAGER_WRITER_LOCKED;
+      pPager->dbHintSize = pPager->dbSize;
+      pPager->dbFileSize = pPager->dbSize;
+      pPager->dbOrigSize = pPager->dbSize;
+      pPager->journalOff = 0;
+    }
+
+    assert( rc==SQLITE_OK || pPager->eState==PAGER_READER );
+    assert( rc!=SQLITE_OK || pPager->eState==PAGER_WRITER_LOCKED );
+    assert( assert_pager_state(pPager) );
+  }
+
+  PAGERTRACE(("TRANSACTION %d\n", PAGERID(pPager)));
+  return rc;
+}
+
+/*
+** Write page pPg onto the end of the rollback journal.
+*/
+static SQLITE_NOINLINE int pagerAddPageToRollbackJournal(PgHdr *pPg){
+  Pager *pPager = pPg->pPager;
+  int rc;
+  u32 cksum;
+  char *pData2;
+  i64 iOff = pPager->journalOff;
+
+  /* We should never write to the journal file the page that
+  ** contains the database locks.  The following assert verifies
+  ** that we do not. */
+  assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) );
+
+  assert( pPager->journalHdr<=pPager->journalOff );
+  CODEC2(pPager, pPg->pData, pPg->pgno, 7, return SQLITE_NOMEM_BKPT, pData2);
+  cksum = pager_cksum(pPager, (u8*)pData2);
+
+  /* Even if an IO or diskfull error occurs while journalling the
+  ** page in the block above, set the need-sync flag for the page.
+  ** Otherwise, when the transaction is rolled back, the logic in
+  ** playback_one_page() will think that the page needs to be restored
+  ** in the database file. And if an IO error occurs while doing so,
+  ** then corruption may follow.
+  */
+  pPg->flags |= PGHDR_NEED_SYNC;
+
+  rc = write32bits(pPager->jfd, iOff, pPg->pgno);
+  if( rc!=SQLITE_OK ) return rc;
+  rc = sqlite3OsWrite(pPager->jfd, pData2, pPager->pageSize, iOff+4);
+  if( rc!=SQLITE_OK ) return rc;
+  rc = write32bits(pPager->jfd, iOff+pPager->pageSize+4, cksum);
+  if( rc!=SQLITE_OK ) return rc;
+
+  IOTRACE(("JOUT %p %d %lld %d\n", pPager, pPg->pgno, 
+           pPager->journalOff, pPager->pageSize));
+  PAGER_INCR(sqlite3_pager_writej_count);
+  PAGERTRACE(("JOURNAL %d page %d needSync=%d hash(%08x)\n",
+       PAGERID(pPager), pPg->pgno, 
+       ((pPg->flags&PGHDR_NEED_SYNC)?1:0), pager_pagehash(pPg)));
+
+  pPager->journalOff += 8 + pPager->pageSize;
+  pPager->nRec++;
+  assert( pPager->pInJournal!=0 );
+  rc = sqlite3BitvecSet(pPager->pInJournal, pPg->pgno);
+  testcase( rc==SQLITE_NOMEM );
+  assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
+  rc |= addToSavepointBitvecs(pPager, pPg->pgno);
+  assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
+  return rc;
+}
+
+/*
+** Mark a single data page as writeable. The page is written into the 
+** main journal or sub-journal as required. If the page is written into
+** one of the journals, the corresponding bit is set in the 
+** Pager.pInJournal bitvec and the PagerSavepoint.pInSavepoint bitvecs
+** of any open savepoints as appropriate.
+*/
+static int pager_write(PgHdr *pPg){
+  Pager *pPager = pPg->pPager;
+  int rc = SQLITE_OK;
+
+  /* This routine is not called unless a write-transaction has already 
+  ** been started. The journal file may or may not be open at this point.
+  ** It is never called in the ERROR state.
+  */
+  assert( pPager->eState==PAGER_WRITER_LOCKED
+       || pPager->eState==PAGER_WRITER_CACHEMOD
+       || pPager->eState==PAGER_WRITER_DBMOD
+  );
+  assert( assert_pager_state(pPager) );
+  assert( pPager->errCode==0 );
+  assert( pPager->readOnly==0 );
+  CHECK_PAGE(pPg);
+
+  /* The journal file needs to be opened. Higher level routines have already
+  ** obtained the necessary locks to begin the write-transaction, but the
+  ** rollback journal might not yet be open. Open it now if this is the case.
+  **
+  ** This is done before calling sqlite3PcacheMakeDirty() on the page. 
+  ** Otherwise, if it were done after calling sqlite3PcacheMakeDirty(), then
+  ** an error might occur and the pager would end up in WRITER_LOCKED state
+  ** with pages marked as dirty in the cache.
+  */
+  if( pPager->eState==PAGER_WRITER_LOCKED ){
+    rc = pager_open_journal(pPager);
+    if( rc!=SQLITE_OK ) return rc;
+  }
+  assert( pPager->eState>=PAGER_WRITER_CACHEMOD );
+  assert( assert_pager_state(pPager) );
+
+  /* Mark the page that is about to be modified as dirty. */
+  sqlite3PcacheMakeDirty(pPg);
+
+  /* If a rollback journal is in use, them make sure the page that is about
+  ** to change is in the rollback journal, or if the page is a new page off
+  ** then end of the file, make sure it is marked as PGHDR_NEED_SYNC.
+  */
+  assert( (pPager->pInJournal!=0) == isOpen(pPager->jfd) );
+  if( pPager->pInJournal!=0
+   && sqlite3BitvecTestNotNull(pPager->pInJournal, pPg->pgno)==0
+  ){
+    assert( pagerUseWal(pPager)==0 );
+    if( pPg->pgno<=pPager->dbOrigSize ){
+      rc = pagerAddPageToRollbackJournal(pPg);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+    }else{
+      if( pPager->eState!=PAGER_WRITER_DBMOD ){
+        pPg->flags |= PGHDR_NEED_SYNC;
+      }
+      PAGERTRACE(("APPEND %d page %d needSync=%d\n",
+              PAGERID(pPager), pPg->pgno,
+             ((pPg->flags&PGHDR_NEED_SYNC)?1:0)));
+    }
+  }
+
+  /* The PGHDR_DIRTY bit is set above when the page was added to the dirty-list
+  ** and before writing the page into the rollback journal.  Wait until now,
+  ** after the page has been successfully journalled, before setting the
+  ** PGHDR_WRITEABLE bit that indicates that the page can be safely modified.
+  */
+  pPg->flags |= PGHDR_WRITEABLE;
+  
+  /* If the statement journal is open and the page is not in it,
+  ** then write the page into the statement journal.
+  */
+  if( pPager->nSavepoint>0 ){
+    rc = subjournalPageIfRequired(pPg);
+  }
+
+  /* Update the database size and return. */
+  if( pPager->dbSize<pPg->pgno ){
+    pPager->dbSize = pPg->pgno;
+  }
+  return rc;
+}
+
+/*
+** This is a variant of sqlite3PagerWrite() that runs when the sector size
+** is larger than the page size.  SQLite makes the (reasonable) assumption that
+** all bytes of a sector are written together by hardware.  Hence, all bytes of
+** a sector need to be journalled in case of a power loss in the middle of
+** a write.
+**
+** Usually, the sector size is less than or equal to the page size, in which
+** case pages can be individually written.  This routine only runs in the
+** exceptional case where the page size is smaller than the sector size.
+*/
+static SQLITE_NOINLINE int pagerWriteLargeSector(PgHdr *pPg){
+  int rc = SQLITE_OK;          /* Return code */
+  Pgno nPageCount;             /* Total number of pages in database file */
+  Pgno pg1;                    /* First page of the sector pPg is located on. */
+  int nPage = 0;               /* Number of pages starting at pg1 to journal */
+  int ii;                      /* Loop counter */
+  int needSync = 0;            /* True if any page has PGHDR_NEED_SYNC */
+  Pager *pPager = pPg->pPager; /* The pager that owns pPg */
+  Pgno nPagePerSector = (pPager->sectorSize/pPager->pageSize);
+
+  /* Set the doNotSpill NOSYNC bit to 1. This is because we cannot allow
+  ** a journal header to be written between the pages journaled by
+  ** this function.
+  */
+  assert( !MEMDB );
+  assert( (pPager->doNotSpill & SPILLFLAG_NOSYNC)==0 );
+  pPager->doNotSpill |= SPILLFLAG_NOSYNC;
+
+  /* This trick assumes that both the page-size and sector-size are
+  ** an integer power of 2. It sets variable pg1 to the identifier
+  ** of the first page of the sector pPg is located on.
+  */
+  pg1 = ((pPg->pgno-1) & ~(nPagePerSector-1)) + 1;
+
+  nPageCount = pPager->dbSize;
+  if( pPg->pgno>nPageCount ){
+    nPage = (pPg->pgno - pg1)+1;
+  }else if( (pg1+nPagePerSector-1)>nPageCount ){
+    nPage = nPageCount+1-pg1;
+  }else{
+    nPage = nPagePerSector;
+  }
+  assert(nPage>0);
+  assert(pg1<=pPg->pgno);
+  assert((pg1+nPage)>pPg->pgno);
+
+  for(ii=0; ii<nPage && rc==SQLITE_OK; ii++){
+    Pgno pg = pg1+ii;
+    PgHdr *pPage;
+    if( pg==pPg->pgno || !sqlite3BitvecTest(pPager->pInJournal, pg) ){
+      if( pg!=PAGER_MJ_PGNO(pPager) ){
+        rc = sqlite3PagerGet(pPager, pg, &pPage, 0);
+        if( rc==SQLITE_OK ){
+          rc = pager_write(pPage);
+          if( pPage->flags&PGHDR_NEED_SYNC ){
+            needSync = 1;
+          }
+          sqlite3PagerUnrefNotNull(pPage);
+        }
+      }
+    }else if( (pPage = sqlite3PagerLookup(pPager, pg))!=0 ){
+      if( pPage->flags&PGHDR_NEED_SYNC ){
+        needSync = 1;
+      }
+      sqlite3PagerUnrefNotNull(pPage);
+    }
+  }
+
+  /* If the PGHDR_NEED_SYNC flag is set for any of the nPage pages 
+  ** starting at pg1, then it needs to be set for all of them. Because
+  ** writing to any of these nPage pages may damage the others, the
+  ** journal file must contain sync()ed copies of all of them
+  ** before any of them can be written out to the database file.
+  */
+  if( rc==SQLITE_OK && needSync ){
+    assert( !MEMDB );
+    for(ii=0; ii<nPage; ii++){
+      PgHdr *pPage = sqlite3PagerLookup(pPager, pg1+ii);
+      if( pPage ){
+        pPage->flags |= PGHDR_NEED_SYNC;
+        sqlite3PagerUnrefNotNull(pPage);
+      }
+    }
+  }
+
+  assert( (pPager->doNotSpill & SPILLFLAG_NOSYNC)!=0 );
+  pPager->doNotSpill &= ~SPILLFLAG_NOSYNC;
+  return rc;
+}
+
+/*
+** Mark a data page as writeable. This routine must be called before 
+** making changes to a page. The caller must check the return value 
+** of this function and be careful not to change any page data unless 
+** this routine returns SQLITE_OK.
+**
+** The difference between this function and pager_write() is that this
+** function also deals with the special case where 2 or more pages
+** fit on a single disk sector. In this case all co-resident pages
+** must have been written to the journal file before returning.
+**
+** If an error occurs, SQLITE_NOMEM or an IO error code is returned
+** as appropriate. Otherwise, SQLITE_OK.
+*/
+SQLITE_PRIVATE int sqlite3PagerWrite(PgHdr *pPg){
+  Pager *pPager = pPg->pPager;
+  assert( (pPg->flags & PGHDR_MMAP)==0 );
+  assert( pPager->eState>=PAGER_WRITER_LOCKED );
+  assert( assert_pager_state(pPager) );
+  if( pPager->errCode ){
+    return pPager->errCode;
+  }else if( (pPg->flags & PGHDR_WRITEABLE)!=0 && pPager->dbSize>=pPg->pgno ){
+    if( pPager->nSavepoint ) return subjournalPageIfRequired(pPg);
+    return SQLITE_OK;
+  }else if( pPager->sectorSize > (u32)pPager->pageSize ){
+    assert( pPager->tempFile==0 );
+    return pagerWriteLargeSector(pPg);
+  }else{
+    return pager_write(pPg);
+  }
+}
+
+/*
+** Return TRUE if the page given in the argument was previously passed
+** to sqlite3PagerWrite().  In other words, return TRUE if it is ok
+** to change the content of the page.
+*/
+#ifndef NDEBUG
+SQLITE_PRIVATE int sqlite3PagerIswriteable(DbPage *pPg){
+  return pPg->flags & PGHDR_WRITEABLE;
+}
+#endif
+
+/*
+** A call to this routine tells the pager that it is not necessary to
+** write the information on page pPg back to the disk, even though
+** that page might be marked as dirty.  This happens, for example, when
+** the page has been added as a leaf of the freelist and so its
+** content no longer matters.
+**
+** The overlying software layer calls this routine when all of the data
+** on the given page is unused. The pager marks the page as clean so
+** that it does not get written to disk.
+**
+** Tests show that this optimization can quadruple the speed of large 
+** DELETE operations.
+**
+** This optimization cannot be used with a temp-file, as the page may
+** have been dirty at the start of the transaction. In that case, if
+** memory pressure forces page pPg out of the cache, the data does need 
+** to be written out to disk so that it may be read back in if the 
+** current transaction is rolled back.
+*/
+SQLITE_PRIVATE void sqlite3PagerDontWrite(PgHdr *pPg){
+  Pager *pPager = pPg->pPager;
+  if( !pPager->tempFile && (pPg->flags&PGHDR_DIRTY) && pPager->nSavepoint==0 ){
+    PAGERTRACE(("DONT_WRITE page %d of %d\n", pPg->pgno, PAGERID(pPager)));
+    IOTRACE(("CLEAN %p %d\n", pPager, pPg->pgno))
+    pPg->flags |= PGHDR_DONT_WRITE;
+    pPg->flags &= ~PGHDR_WRITEABLE;
+    testcase( pPg->flags & PGHDR_NEED_SYNC );
+    pager_set_pagehash(pPg);
+  }
+}
+
+/*
+** This routine is called to increment the value of the database file 
+** change-counter, stored as a 4-byte big-endian integer starting at 
+** byte offset 24 of the pager file.  The secondary change counter at
+** 92 is also updated, as is the SQLite version number at offset 96.
+**
+** But this only happens if the pPager->changeCountDone flag is false.
+** To avoid excess churning of page 1, the update only happens once.
+** See also the pager_write_changecounter() routine that does an 
+** unconditional update of the change counters.
+**
+** If the isDirectMode flag is zero, then this is done by calling 
+** sqlite3PagerWrite() on page 1, then modifying the contents of the
+** page data. In this case the file will be updated when the current
+** transaction is committed.
+**
+** The isDirectMode flag may only be non-zero if the library was compiled
+** with the SQLITE_ENABLE_ATOMIC_WRITE macro defined. In this case,
+** if isDirect is non-zero, then the database file is updated directly
+** by writing an updated version of page 1 using a call to the 
+** sqlite3OsWrite() function.
+*/
+static int pager_incr_changecounter(Pager *pPager, int isDirectMode){
+  int rc = SQLITE_OK;
+
+  assert( pPager->eState==PAGER_WRITER_CACHEMOD
+       || pPager->eState==PAGER_WRITER_DBMOD
+  );
+  assert( assert_pager_state(pPager) );
+
+  /* Declare and initialize constant integer 'isDirect'. If the
+  ** atomic-write optimization is enabled in this build, then isDirect
+  ** is initialized to the value passed as the isDirectMode parameter
+  ** to this function. Otherwise, it is always set to zero.
+  **
+  ** The idea is that if the atomic-write optimization is not
+  ** enabled at compile time, the compiler can omit the tests of
+  ** 'isDirect' below, as well as the block enclosed in the
+  ** "if( isDirect )" condition.
+  */
+#ifndef SQLITE_ENABLE_ATOMIC_WRITE
+# define DIRECT_MODE 0
+  assert( isDirectMode==0 );
+  UNUSED_PARAMETER(isDirectMode);
+#else
+# define DIRECT_MODE isDirectMode
+#endif
+
+  if( !pPager->changeCountDone && ALWAYS(pPager->dbSize>0) ){
+    PgHdr *pPgHdr;                /* Reference to page 1 */
+
+    assert( !pPager->tempFile && isOpen(pPager->fd) );
+
+    /* Open page 1 of the file for writing. */
+    rc = sqlite3PagerGet(pPager, 1, &pPgHdr, 0);
+    assert( pPgHdr==0 || rc==SQLITE_OK );
+
+    /* If page one was fetched successfully, and this function is not
+    ** operating in direct-mode, make page 1 writable.  When not in 
+    ** direct mode, page 1 is always held in cache and hence the PagerGet()
+    ** above is always successful - hence the ALWAYS on rc==SQLITE_OK.
+    */
+    if( !DIRECT_MODE && ALWAYS(rc==SQLITE_OK) ){
+      rc = sqlite3PagerWrite(pPgHdr);
+    }
+
+    if( rc==SQLITE_OK ){
+      /* Actually do the update of the change counter */
+      pager_write_changecounter(pPgHdr);
+
+      /* If running in direct mode, write the contents of page 1 to the file. */
+      if( DIRECT_MODE ){
+        const void *zBuf;
+        assert( pPager->dbFileSize>0 );
+        CODEC2(pPager, pPgHdr->pData, 1, 6, rc=SQLITE_NOMEM_BKPT, zBuf);
+        if( rc==SQLITE_OK ){
+          rc = sqlite3OsWrite(pPager->fd, zBuf, pPager->pageSize, 0);
+          pPager->aStat[PAGER_STAT_WRITE]++;
+        }
+        if( rc==SQLITE_OK ){
+          /* Update the pager's copy of the change-counter. Otherwise, the
+          ** next time a read transaction is opened the cache will be
+          ** flushed (as the change-counter values will not match).  */
+          const void *pCopy = (const void *)&((const char *)zBuf)[24];
+          memcpy(&pPager->dbFileVers, pCopy, sizeof(pPager->dbFileVers));
+          pPager->changeCountDone = 1;
+        }
+      }else{
+        pPager->changeCountDone = 1;
+      }
+    }
+
+    /* Release the page reference. */
+    sqlite3PagerUnref(pPgHdr);
+  }
+  return rc;
+}
+
+/*
+** Sync the database file to disk. This is a no-op for in-memory databases
+** or pages with the Pager.noSync flag set.
+**
+** If successful, or if called on a pager for which it is a no-op, this
+** function returns SQLITE_OK. Otherwise, an IO error code is returned.
+*/
+SQLITE_PRIVATE int sqlite3PagerSync(Pager *pPager, const char *zMaster){
+  int rc = SQLITE_OK;
+
+  if( isOpen(pPager->fd) ){
+    void *pArg = (void*)zMaster;
+    rc = sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_SYNC, pArg);
+    if( rc==SQLITE_NOTFOUND ) rc = SQLITE_OK;
+  }
+  if( rc==SQLITE_OK && !pPager->noSync ){
+    assert( !MEMDB );
+    rc = sqlite3OsSync(pPager->fd, pPager->syncFlags);
+  }
+  return rc;
+}
+
+/*
+** This function may only be called while a write-transaction is active in
+** rollback. If the connection is in WAL mode, this call is a no-op. 
+** Otherwise, if the connection does not already have an EXCLUSIVE lock on 
+** the database file, an attempt is made to obtain one.
+**
+** If the EXCLUSIVE lock is already held or the attempt to obtain it is
+** successful, or the connection is in WAL mode, SQLITE_OK is returned.
+** Otherwise, either SQLITE_BUSY or an SQLITE_IOERR_XXX error code is 
+** returned.
+*/
+SQLITE_PRIVATE int sqlite3PagerExclusiveLock(Pager *pPager){
+  int rc = pPager->errCode;
+  assert( assert_pager_state(pPager) );
+  if( rc==SQLITE_OK ){
+    assert( pPager->eState==PAGER_WRITER_CACHEMOD 
+         || pPager->eState==PAGER_WRITER_DBMOD 
+         || pPager->eState==PAGER_WRITER_LOCKED 
+    );
+    assert( assert_pager_state(pPager) );
+    if( 0==pagerUseWal(pPager) ){
+      rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
+    }
+  }
+  return rc;
+}
+
+/*
+** Sync the database file for the pager pPager. zMaster points to the name
+** of a master journal file that should be written into the individual
+** journal file. zMaster may be NULL, which is interpreted as no master
+** journal (a single database transaction).
+**
+** This routine ensures that:
+**
+**   * The database file change-counter is updated,
+**   * the journal is synced (unless the atomic-write optimization is used),
+**   * all dirty pages are written to the database file, 
+**   * the database file is truncated (if required), and
+**   * the database file synced. 
+**
+** The only thing that remains to commit the transaction is to finalize 
+** (delete, truncate or zero the first part of) the journal file (or 
+** delete the master journal file if specified).
+**
+** Note that if zMaster==NULL, this does not overwrite a previous value
+** passed to an sqlite3PagerCommitPhaseOne() call.
+**
+** If the final parameter - noSync - is true, then the database file itself
+** is not synced. The caller must call sqlite3PagerSync() directly to
+** sync the database file before calling CommitPhaseTwo() to delete the
+** journal file in this case.
+*/
+SQLITE_PRIVATE int sqlite3PagerCommitPhaseOne(
+  Pager *pPager,                  /* Pager object */
+  const char *zMaster,            /* If not NULL, the master journal name */
+  int noSync                      /* True to omit the xSync on the db file */
+){
+  int rc = SQLITE_OK;             /* Return code */
+
+  assert( pPager->eState==PAGER_WRITER_LOCKED
+       || pPager->eState==PAGER_WRITER_CACHEMOD
+       || pPager->eState==PAGER_WRITER_DBMOD
+       || pPager->eState==PAGER_ERROR
+  );
+  assert( assert_pager_state(pPager) );
+
+  /* If a prior error occurred, report that error again. */
+  if( NEVER(pPager->errCode) ) return pPager->errCode;
+
+  /* Provide the ability to easily simulate an I/O error during testing */
+  if( sqlite3FaultSim(400) ) return SQLITE_IOERR;
+
+  PAGERTRACE(("DATABASE SYNC: File=%s zMaster=%s nSize=%d\n", 
+      pPager->zFilename, zMaster, pPager->dbSize));
+
+  /* If no database changes have been made, return early. */
+  if( pPager->eState<PAGER_WRITER_CACHEMOD ) return SQLITE_OK;
+
+  assert( MEMDB==0 || pPager->tempFile );
+  assert( isOpen(pPager->fd) || pPager->tempFile );
+  if( 0==pagerFlushOnCommit(pPager, 1) ){
+    /* If this is an in-memory db, or no pages have been written to, or this
+    ** function has already been called, it is mostly a no-op.  However, any
+    ** backup in progress needs to be restarted.  */
+    sqlite3BackupRestart(pPager->pBackup);
+  }else{
+    if( pagerUseWal(pPager) ){
+      PgHdr *pList = sqlite3PcacheDirtyList(pPager->pPCache);
+      PgHdr *pPageOne = 0;
+      if( pList==0 ){
+        /* Must have at least one page for the WAL commit flag.
+        ** Ticket [2d1a5c67dfc2363e44f29d9bbd57f] 2011-05-18 */
+        rc = sqlite3PagerGet(pPager, 1, &pPageOne, 0);
+        pList = pPageOne;
+        pList->pDirty = 0;
+      }
+      assert( rc==SQLITE_OK );
+      if( ALWAYS(pList) ){
+        rc = pagerWalFrames(pPager, pList, pPager->dbSize, 1);
+      }
+      sqlite3PagerUnref(pPageOne);
+      if( rc==SQLITE_OK ){
+        sqlite3PcacheCleanAll(pPager->pPCache);
+      }
+    }else{
+      /* The following block updates the change-counter. Exactly how it
+      ** does this depends on whether or not the atomic-update optimization
+      ** was enabled at compile time, and if this transaction meets the 
+      ** runtime criteria to use the operation: 
+      **
+      **    * The file-system supports the atomic-write property for
+      **      blocks of size page-size, and 
+      **    * This commit is not part of a multi-file transaction, and
+      **    * Exactly one page has been modified and store in the journal file.
+      **
+      ** If the optimization was not enabled at compile time, then the
+      ** pager_incr_changecounter() function is called to update the change
+      ** counter in 'indirect-mode'. If the optimization is compiled in but
+      ** is not applicable to this transaction, call sqlite3JournalCreate()
+      ** to make sure the journal file has actually been created, then call
+      ** pager_incr_changecounter() to update the change-counter in indirect
+      ** mode. 
+      **
+      ** Otherwise, if the optimization is both enabled and applicable,
+      ** then call pager_incr_changecounter() to update the change-counter
+      ** in 'direct' mode. In this case the journal file will never be
+      ** created for this transaction.
+      */
+  #ifdef SQLITE_ENABLE_ATOMIC_WRITE
+      PgHdr *pPg;
+      assert( isOpen(pPager->jfd) 
+           || pPager->journalMode==PAGER_JOURNALMODE_OFF 
+           || pPager->journalMode==PAGER_JOURNALMODE_WAL 
+      );
+      if( !zMaster && isOpen(pPager->jfd) 
+       && pPager->journalOff==jrnlBufferSize(pPager) 
+       && pPager->dbSize>=pPager->dbOrigSize
+       && (0==(pPg = sqlite3PcacheDirtyList(pPager->pPCache)) || 0==pPg->pDirty)
+      ){
+        /* Update the db file change counter via the direct-write method. The 
+        ** following call will modify the in-memory representation of page 1 
+        ** to include the updated change counter and then write page 1 
+        ** directly to the database file. Because of the atomic-write 
+        ** property of the host file-system, this is safe.
+        */
+        rc = pager_incr_changecounter(pPager, 1);
+      }else{
+        rc = sqlite3JournalCreate(pPager->jfd);
+        if( rc==SQLITE_OK ){
+          rc = pager_incr_changecounter(pPager, 0);
+        }
+      }
+  #else
+      rc = pager_incr_changecounter(pPager, 0);
+  #endif
+      if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
+  
+      /* Write the master journal name into the journal file. If a master 
+      ** journal file name has already been written to the journal file, 
+      ** or if zMaster is NULL (no master journal), then this call is a no-op.
+      */
+      rc = writeMasterJournal(pPager, zMaster);
+      if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
+  
+      /* Sync the journal file and write all dirty pages to the database.
+      ** If the atomic-update optimization is being used, this sync will not 
+      ** create the journal file or perform any real IO.
+      **
+      ** Because the change-counter page was just modified, unless the
+      ** atomic-update optimization is used it is almost certain that the
+      ** journal requires a sync here. However, in locking_mode=exclusive
+      ** on a system under memory pressure it is just possible that this is 
+      ** not the case. In this case it is likely enough that the redundant
+      ** xSync() call will be changed to a no-op by the OS anyhow. 
+      */
+      rc = syncJournal(pPager, 0);
+      if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
+  
+      rc = pager_write_pagelist(pPager,sqlite3PcacheDirtyList(pPager->pPCache));
+      if( rc!=SQLITE_OK ){
+        assert( rc!=SQLITE_IOERR_BLOCKED );
+        goto commit_phase_one_exit;
+      }
+      sqlite3PcacheCleanAll(pPager->pPCache);
+
+      /* If the file on disk is smaller than the database image, use 
+      ** pager_truncate to grow the file here. This can happen if the database
+      ** image was extended as part of the current transaction and then the
+      ** last page in the db image moved to the free-list. In this case the
+      ** last page is never written out to disk, leaving the database file
+      ** undersized. Fix this now if it is the case.  */
+      if( pPager->dbSize>pPager->dbFileSize ){
+        Pgno nNew = pPager->dbSize - (pPager->dbSize==PAGER_MJ_PGNO(pPager));
+        assert( pPager->eState==PAGER_WRITER_DBMOD );
+        rc = pager_truncate(pPager, nNew);
+        if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
+      }
+  
+      /* Finally, sync the database file. */
+      if( !noSync ){
+        rc = sqlite3PagerSync(pPager, zMaster);
+      }
+      IOTRACE(("DBSYNC %p\n", pPager))
+    }
+  }
+
+commit_phase_one_exit:
+  if( rc==SQLITE_OK && !pagerUseWal(pPager) ){
+    pPager->eState = PAGER_WRITER_FINISHED;
+  }
+  return rc;
+}
+
+
+/*
+** When this function is called, the database file has been completely
+** updated to reflect the changes made by the current transaction and
+** synced to disk. The journal file still exists in the file-system 
+** though, and if a failure occurs at this point it will eventually
+** be used as a hot-journal and the current transaction rolled back.
+**
+** This function finalizes the journal file, either by deleting, 
+** truncating or partially zeroing it, so that it cannot be used 
+** for hot-journal rollback. Once this is done the transaction is
+** irrevocably committed.
+**
+** If an error occurs, an IO error code is returned and the pager
+** moves into the error state. Otherwise, SQLITE_OK is returned.
+*/
+SQLITE_PRIVATE int sqlite3PagerCommitPhaseTwo(Pager *pPager){
+  int rc = SQLITE_OK;                  /* Return code */
+
+  /* This routine should not be called if a prior error has occurred.
+  ** But if (due to a coding error elsewhere in the system) it does get
+  ** called, just return the same error code without doing anything. */
+  if( NEVER(pPager->errCode) ) return pPager->errCode;
+
+  assert( pPager->eState==PAGER_WRITER_LOCKED
+       || pPager->eState==PAGER_WRITER_FINISHED
+       || (pagerUseWal(pPager) && pPager->eState==PAGER_WRITER_CACHEMOD)
+  );
+  assert( assert_pager_state(pPager) );
+
+  /* An optimization. If the database was not actually modified during
+  ** this transaction, the pager is running in exclusive-mode and is
+  ** using persistent journals, then this function is a no-op.
+  **
+  ** The start of the journal file currently contains a single journal 
+  ** header with the nRec field set to 0. If such a journal is used as
+  ** a hot-journal during hot-journal rollback, 0 changes will be made
+  ** to the database file. So there is no need to zero the journal 
+  ** header. Since the pager is in exclusive mode, there is no need
+  ** to drop any locks either.
+  */
+  if( pPager->eState==PAGER_WRITER_LOCKED 
+   && pPager->exclusiveMode 
+   && pPager->journalMode==PAGER_JOURNALMODE_PERSIST
+  ){
+    assert( pPager->journalOff==JOURNAL_HDR_SZ(pPager) || !pPager->journalOff );
+    pPager->eState = PAGER_READER;
+    return SQLITE_OK;
+  }
+
+  PAGERTRACE(("COMMIT %d\n", PAGERID(pPager)));
+  pPager->iDataVersion++;
+  rc = pager_end_transaction(pPager, pPager->setMaster, 1);
+  return pager_error(pPager, rc);
+}
+
+/*
+** If a write transaction is open, then all changes made within the 
+** transaction are reverted and the current write-transaction is closed.
+** The pager falls back to PAGER_READER state if successful, or PAGER_ERROR
+** state if an error occurs.
+**
+** If the pager is already in PAGER_ERROR state when this function is called,
+** it returns Pager.errCode immediately. No work is performed in this case.
+**
+** Otherwise, in rollback mode, this function performs two functions:
+**
+**   1) It rolls back the journal file, restoring all database file and 
+**      in-memory cache pages to the state they were in when the transaction
+**      was opened, and
+**
+**   2) It finalizes the journal file, so that it is not used for hot
+**      rollback at any point in the future.
+**
+** Finalization of the journal file (task 2) is only performed if the 
+** rollback is successful.
+**
+** In WAL mode, all cache-entries containing data modified within the
+** current transaction are either expelled from the cache or reverted to
+** their pre-transaction state by re-reading data from the database or
+** WAL files. The WAL transaction is then closed.
+*/
+SQLITE_PRIVATE int sqlite3PagerRollback(Pager *pPager){
+  int rc = SQLITE_OK;                  /* Return code */
+  PAGERTRACE(("ROLLBACK %d\n", PAGERID(pPager)));
+
+  /* PagerRollback() is a no-op if called in READER or OPEN state. If
+  ** the pager is already in the ERROR state, the rollback is not 
+  ** attempted here. Instead, the error code is returned to the caller.
+  */
+  assert( assert_pager_state(pPager) );
+  if( pPager->eState==PAGER_ERROR ) return pPager->errCode;
+  if( pPager->eState<=PAGER_READER ) return SQLITE_OK;
+
+  if( pagerUseWal(pPager) ){
+    int rc2;
+    rc = sqlite3PagerSavepoint(pPager, SAVEPOINT_ROLLBACK, -1);
+    rc2 = pager_end_transaction(pPager, pPager->setMaster, 0);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }else if( !isOpen(pPager->jfd) || pPager->eState==PAGER_WRITER_LOCKED ){
+    int eState = pPager->eState;
+    rc = pager_end_transaction(pPager, 0, 0);
+    if( !MEMDB && eState>PAGER_WRITER_LOCKED ){
+      /* This can happen using journal_mode=off. Move the pager to the error 
+      ** state to indicate that the contents of the cache may not be trusted.
+      ** Any active readers will get SQLITE_ABORT.
+      */
+      pPager->errCode = SQLITE_ABORT;
+      pPager->eState = PAGER_ERROR;
+      return rc;
+    }
+  }else{
+    rc = pager_playback(pPager, 0);
+  }
+
+  assert( pPager->eState==PAGER_READER || rc!=SQLITE_OK );
+  assert( rc==SQLITE_OK || rc==SQLITE_FULL || rc==SQLITE_CORRUPT
+          || rc==SQLITE_NOMEM || (rc&0xFF)==SQLITE_IOERR 
+          || rc==SQLITE_CANTOPEN
+  );
+
+  /* If an error occurs during a ROLLBACK, we can no longer trust the pager
+  ** cache. So call pager_error() on the way out to make any error persistent.
+  */
+  return pager_error(pPager, rc);
+}
+
+/*
+** Return TRUE if the database file is opened read-only.  Return FALSE
+** if the database is (in theory) writable.
+*/
+SQLITE_PRIVATE u8 sqlite3PagerIsreadonly(Pager *pPager){
+  return pPager->readOnly;
+}
+
+#ifdef SQLITE_DEBUG
+/*
+** Return the sum of the reference counts for all pages held by pPager.
+*/
+SQLITE_PRIVATE int sqlite3PagerRefcount(Pager *pPager){
+  return sqlite3PcacheRefCount(pPager->pPCache);
+}
+#endif
+
+/*
+** Return the approximate number of bytes of memory currently
+** used by the pager and its associated cache.
+*/
+SQLITE_PRIVATE int sqlite3PagerMemUsed(Pager *pPager){
+  int perPageSize = pPager->pageSize + pPager->nExtra + sizeof(PgHdr)
+                                     + 5*sizeof(void*);
+  return perPageSize*sqlite3PcachePagecount(pPager->pPCache)
+           + sqlite3MallocSize(pPager)
+           + pPager->pageSize;
+}
+
+/*
+** Return the number of references to the specified page.
+*/
+SQLITE_PRIVATE int sqlite3PagerPageRefcount(DbPage *pPage){
+  return sqlite3PcachePageRefcount(pPage);
+}
+
+#ifdef SQLITE_TEST
+/*
+** This routine is used for testing and analysis only.
+*/
+SQLITE_PRIVATE int *sqlite3PagerStats(Pager *pPager){
+  static int a[11];
+  a[0] = sqlite3PcacheRefCount(pPager->pPCache);
+  a[1] = sqlite3PcachePagecount(pPager->pPCache);
+  a[2] = sqlite3PcacheGetCachesize(pPager->pPCache);
+  a[3] = pPager->eState==PAGER_OPEN ? -1 : (int) pPager->dbSize;
+  a[4] = pPager->eState;
+  a[5] = pPager->errCode;
+  a[6] = pPager->aStat[PAGER_STAT_HIT];
+  a[7] = pPager->aStat[PAGER_STAT_MISS];
+  a[8] = 0;  /* Used to be pPager->nOvfl */
+  a[9] = pPager->nRead;
+  a[10] = pPager->aStat[PAGER_STAT_WRITE];
+  return a;
+}
+#endif
+
+/*
+** Parameter eStat must be either SQLITE_DBSTATUS_CACHE_HIT or
+** SQLITE_DBSTATUS_CACHE_MISS. Before returning, *pnVal is incremented by the
+** current cache hit or miss count, according to the value of eStat. If the 
+** reset parameter is non-zero, the cache hit or miss count is zeroed before 
+** returning.
+*/
+SQLITE_PRIVATE void sqlite3PagerCacheStat(Pager *pPager, int eStat, int reset, int *pnVal){
+
+  assert( eStat==SQLITE_DBSTATUS_CACHE_HIT
+       || eStat==SQLITE_DBSTATUS_CACHE_MISS
+       || eStat==SQLITE_DBSTATUS_CACHE_WRITE
+  );
+
+  assert( SQLITE_DBSTATUS_CACHE_HIT+1==SQLITE_DBSTATUS_CACHE_MISS );
+  assert( SQLITE_DBSTATUS_CACHE_HIT+2==SQLITE_DBSTATUS_CACHE_WRITE );
+  assert( PAGER_STAT_HIT==0 && PAGER_STAT_MISS==1 && PAGER_STAT_WRITE==2 );
+
+  *pnVal += pPager->aStat[eStat - SQLITE_DBSTATUS_CACHE_HIT];
+  if( reset ){
+    pPager->aStat[eStat - SQLITE_DBSTATUS_CACHE_HIT] = 0;
+  }
+}
+
+/*
+** Return true if this is an in-memory or temp-file backed pager.
+*/
+SQLITE_PRIVATE int sqlite3PagerIsMemdb(Pager *pPager){
+  return pPager->tempFile;
+}
+
+/*
+** Check that there are at least nSavepoint savepoints open. If there are
+** currently less than nSavepoints open, then open one or more savepoints
+** to make up the difference. If the number of savepoints is already
+** equal to nSavepoint, then this function is a no-op.
+**
+** If a memory allocation fails, SQLITE_NOMEM is returned. If an error 
+** occurs while opening the sub-journal file, then an IO error code is
+** returned. Otherwise, SQLITE_OK.
+*/
+static SQLITE_NOINLINE int pagerOpenSavepoint(Pager *pPager, int nSavepoint){
+  int rc = SQLITE_OK;                       /* Return code */
+  int nCurrent = pPager->nSavepoint;        /* Current number of savepoints */
+  int ii;                                   /* Iterator variable */
+  PagerSavepoint *aNew;                     /* New Pager.aSavepoint array */
+
+  assert( pPager->eState>=PAGER_WRITER_LOCKED );
+  assert( assert_pager_state(pPager) );
+  assert( nSavepoint>nCurrent && pPager->useJournal );
+
+  /* Grow the Pager.aSavepoint array using realloc(). Return SQLITE_NOMEM
+  ** if the allocation fails. Otherwise, zero the new portion in case a 
+  ** malloc failure occurs while populating it in the for(...) loop below.
+  */
+  aNew = (PagerSavepoint *)sqlite3Realloc(
+      pPager->aSavepoint, sizeof(PagerSavepoint)*nSavepoint
+  );
+  if( !aNew ){
+    return SQLITE_NOMEM_BKPT;
+  }
+  memset(&aNew[nCurrent], 0, (nSavepoint-nCurrent) * sizeof(PagerSavepoint));
+  pPager->aSavepoint = aNew;
+
+  /* Populate the PagerSavepoint structures just allocated. */
+  for(ii=nCurrent; ii<nSavepoint; ii++){
+    aNew[ii].nOrig = pPager->dbSize;
+    if( isOpen(pPager->jfd) && pPager->journalOff>0 ){
+      aNew[ii].iOffset = pPager->journalOff;
+    }else{
+      aNew[ii].iOffset = JOURNAL_HDR_SZ(pPager);
+    }
+    aNew[ii].iSubRec = pPager->nSubRec;
+    aNew[ii].pInSavepoint = sqlite3BitvecCreate(pPager->dbSize);
+    if( !aNew[ii].pInSavepoint ){
+      return SQLITE_NOMEM_BKPT;
+    }
+    if( pagerUseWal(pPager) ){
+      sqlite3WalSavepoint(pPager->pWal, aNew[ii].aWalData);
+    }
+    pPager->nSavepoint = ii+1;
+  }
+  assert( pPager->nSavepoint==nSavepoint );
+  assertTruncateConstraint(pPager);
+  return rc;
+}
+SQLITE_PRIVATE int sqlite3PagerOpenSavepoint(Pager *pPager, int nSavepoint){
+  assert( pPager->eState>=PAGER_WRITER_LOCKED );
+  assert( assert_pager_state(pPager) );
+
+  if( nSavepoint>pPager->nSavepoint && pPager->useJournal ){
+    return pagerOpenSavepoint(pPager, nSavepoint);
+  }else{
+    return SQLITE_OK;
+  }
+}
+
+
+/*
+** This function is called to rollback or release (commit) a savepoint.
+** The savepoint to release or rollback need not be the most recently 
+** created savepoint.
+**
+** Parameter op is always either SAVEPOINT_ROLLBACK or SAVEPOINT_RELEASE.
+** If it is SAVEPOINT_RELEASE, then release and destroy the savepoint with
+** index iSavepoint. If it is SAVEPOINT_ROLLBACK, then rollback all changes
+** that have occurred since the specified savepoint was created.
+**
+** The savepoint to rollback or release is identified by parameter 
+** iSavepoint. A value of 0 means to operate on the outermost savepoint
+** (the first created). A value of (Pager.nSavepoint-1) means operate
+** on the most recently created savepoint. If iSavepoint is greater than
+** (Pager.nSavepoint-1), then this function is a no-op.
+**
+** If a negative value is passed to this function, then the current
+** transaction is rolled back. This is different to calling 
+** sqlite3PagerRollback() because this function does not terminate
+** the transaction or unlock the database, it just restores the 
+** contents of the database to its original state. 
+**
+** In any case, all savepoints with an index greater than iSavepoint 
+** are destroyed. If this is a release operation (op==SAVEPOINT_RELEASE),
+** then savepoint iSavepoint is also destroyed.
+**
+** This function may return SQLITE_NOMEM if a memory allocation fails,
+** or an IO error code if an IO error occurs while rolling back a 
+** savepoint. If no errors occur, SQLITE_OK is returned.
+*/ 
+SQLITE_PRIVATE int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint){
+  int rc = pPager->errCode;
+  
+#ifdef SQLITE_ENABLE_ZIPVFS
+  if( op==SAVEPOINT_RELEASE ) rc = SQLITE_OK;
+#endif
+
+  assert( op==SAVEPOINT_RELEASE || op==SAVEPOINT_ROLLBACK );
+  assert( iSavepoint>=0 || op==SAVEPOINT_ROLLBACK );
+
+  if( rc==SQLITE_OK && iSavepoint<pPager->nSavepoint ){
+    int ii;            /* Iterator variable */
+    int nNew;          /* Number of remaining savepoints after this op. */
+
+    /* Figure out how many savepoints will still be active after this
+    ** operation. Store this value in nNew. Then free resources associated 
+    ** with any savepoints that are destroyed by this operation.
+    */
+    nNew = iSavepoint + (( op==SAVEPOINT_RELEASE ) ? 0 : 1);
+    for(ii=nNew; ii<pPager->nSavepoint; ii++){
+      sqlite3BitvecDestroy(pPager->aSavepoint[ii].pInSavepoint);
+    }
+    pPager->nSavepoint = nNew;
+
+    /* If this is a release of the outermost savepoint, truncate 
+    ** the sub-journal to zero bytes in size. */
+    if( op==SAVEPOINT_RELEASE ){
+      if( nNew==0 && isOpen(pPager->sjfd) ){
+        /* Only truncate if it is an in-memory sub-journal. */
+        if( sqlite3JournalIsInMemory(pPager->sjfd) ){
+          rc = sqlite3OsTruncate(pPager->sjfd, 0);
+          assert( rc==SQLITE_OK );
+        }
+        pPager->nSubRec = 0;
+      }
+    }
+    /* Else this is a rollback operation, playback the specified savepoint.
+    ** If this is a temp-file, it is possible that the journal file has
+    ** not yet been opened. In this case there have been no changes to
+    ** the database file, so the playback operation can be skipped.
+    */
+    else if( pagerUseWal(pPager) || isOpen(pPager->jfd) ){
+      PagerSavepoint *pSavepoint = (nNew==0)?0:&pPager->aSavepoint[nNew-1];
+      rc = pagerPlaybackSavepoint(pPager, pSavepoint);
+      assert(rc!=SQLITE_DONE);
+    }
+    
+#ifdef SQLITE_ENABLE_ZIPVFS
+    /* If the cache has been modified but the savepoint cannot be rolled 
+    ** back journal_mode=off, put the pager in the error state. This way,
+    ** if the VFS used by this pager includes ZipVFS, the entire transaction
+    ** can be rolled back at the ZipVFS level.  */
+    else if( 
+        pPager->journalMode==PAGER_JOURNALMODE_OFF 
+     && pPager->eState>=PAGER_WRITER_CACHEMOD
+    ){
+      pPager->errCode = SQLITE_ABORT;
+      pPager->eState = PAGER_ERROR;
+    }
+#endif
+  }
+
+  return rc;
+}
+
+/*
+** Return the full pathname of the database file.
+**
+** Except, if the pager is in-memory only, then return an empty string if
+** nullIfMemDb is true.  This routine is called with nullIfMemDb==1 when
+** used to report the filename to the user, for compatibility with legacy
+** behavior.  But when the Btree needs to know the filename for matching to
+** shared cache, it uses nullIfMemDb==0 so that in-memory databases can
+** participate in shared-cache.
+*/
+SQLITE_PRIVATE const char *sqlite3PagerFilename(Pager *pPager, int nullIfMemDb){
+  return (nullIfMemDb && pPager->memDb) ? "" : pPager->zFilename;
+}
+
+/*
+** Return the VFS structure for the pager.
+*/
+SQLITE_PRIVATE sqlite3_vfs *sqlite3PagerVfs(Pager *pPager){
+  return pPager->pVfs;
+}
+
+/*
+** Return the file handle for the database file associated
+** with the pager.  This might return NULL if the file has
+** not yet been opened.
+*/
+SQLITE_PRIVATE sqlite3_file *sqlite3PagerFile(Pager *pPager){
+  return pPager->fd;
+}
+
+/*
+** Return the file handle for the journal file (if it exists).
+** This will be either the rollback journal or the WAL file.
+*/
+SQLITE_PRIVATE sqlite3_file *sqlite3PagerJrnlFile(Pager *pPager){
+#if SQLITE_OMIT_WAL
+  return pPager->jfd;
+#else
+  return pPager->pWal ? sqlite3WalFile(pPager->pWal) : pPager->jfd;
+#endif
+}
+
+/*
+** Return the full pathname of the journal file.
+*/
+SQLITE_PRIVATE const char *sqlite3PagerJournalname(Pager *pPager){
+  return pPager->zJournal;
+}
+
+#ifdef SQLITE_HAS_CODEC
+/*
+** Set or retrieve the codec for this pager
+*/
+SQLITE_PRIVATE void sqlite3PagerSetCodec(
+  Pager *pPager,
+  void *(*xCodec)(void*,void*,Pgno,int),
+  void (*xCodecSizeChng)(void*,int,int),
+  void (*xCodecFree)(void*),
+  void *pCodec
+){
+  if( pPager->xCodecFree ) pPager->xCodecFree(pPager->pCodec);
+  pPager->xCodec = pPager->memDb ? 0 : xCodec;
+  pPager->xCodecSizeChng = xCodecSizeChng;
+  pPager->xCodecFree = xCodecFree;
+  pPager->pCodec = pCodec;
+  pagerReportSize(pPager);
+}
+SQLITE_PRIVATE void *sqlite3PagerGetCodec(Pager *pPager){
+  return pPager->pCodec;
+}
+
+/*
+** This function is called by the wal module when writing page content
+** into the log file.
+**
+** This function returns a pointer to a buffer containing the encrypted
+** page content. If a malloc fails, this function may return NULL.
+*/
+SQLITE_PRIVATE void *sqlite3PagerCodec(PgHdr *pPg){
+  void *aData = 0;
+  CODEC2(pPg->pPager, pPg->pData, pPg->pgno, 6, return 0, aData);
+  return aData;
+}
+
+/*
+** Return the current pager state
+*/
+SQLITE_PRIVATE int sqlite3PagerState(Pager *pPager){
+  return pPager->eState;
+}
+#endif /* SQLITE_HAS_CODEC */
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+/*
+** Move the page pPg to location pgno in the file.
+**
+** There must be no references to the page previously located at
+** pgno (which we call pPgOld) though that page is allowed to be
+** in cache.  If the page previously located at pgno is not already
+** in the rollback journal, it is not put there by by this routine.
+**
+** References to the page pPg remain valid. Updating any
+** meta-data associated with pPg (i.e. data stored in the nExtra bytes
+** allocated along with the page) is the responsibility of the caller.
+**
+** A transaction must be active when this routine is called. It used to be
+** required that a statement transaction was not active, but this restriction
+** has been removed (CREATE INDEX needs to move a page when a statement
+** transaction is active).
+**
+** If the fourth argument, isCommit, is non-zero, then this page is being
+** moved as part of a database reorganization just before the transaction 
+** is being committed. In this case, it is guaranteed that the database page 
+** pPg refers to will not be written to again within this transaction.
+**
+** This function may return SQLITE_NOMEM or an IO error code if an error
+** occurs. Otherwise, it returns SQLITE_OK.
+*/
+SQLITE_PRIVATE int sqlite3PagerMovepage(Pager *pPager, DbPage *pPg, Pgno pgno, int isCommit){
+  PgHdr *pPgOld;               /* The page being overwritten. */
+  Pgno needSyncPgno = 0;       /* Old value of pPg->pgno, if sync is required */
+  int rc;                      /* Return code */
+  Pgno origPgno;               /* The original page number */
+
+  assert( pPg->nRef>0 );
+  assert( pPager->eState==PAGER_WRITER_CACHEMOD
+       || pPager->eState==PAGER_WRITER_DBMOD
+  );
+  assert( assert_pager_state(pPager) );
+
+  /* In order to be able to rollback, an in-memory database must journal
+  ** the page we are moving from.
+  */
+  assert( pPager->tempFile || !MEMDB );
+  if( pPager->tempFile ){
+    rc = sqlite3PagerWrite(pPg);
+    if( rc ) return rc;
+  }
+
+  /* If the page being moved is dirty and has not been saved by the latest
+  ** savepoint, then save the current contents of the page into the 
+  ** sub-journal now. This is required to handle the following scenario:
+  **
+  **   BEGIN;
+  **     <journal page X, then modify it in memory>
+  **     SAVEPOINT one;
+  **       <Move page X to location Y>
+  **     ROLLBACK TO one;
+  **
+  ** If page X were not written to the sub-journal here, it would not
+  ** be possible to restore its contents when the "ROLLBACK TO one"
+  ** statement were is processed.
+  **
+  ** subjournalPage() may need to allocate space to store pPg->pgno into
+  ** one or more savepoint bitvecs. This is the reason this function
+  ** may return SQLITE_NOMEM.
+  */
+  if( (pPg->flags & PGHDR_DIRTY)!=0
+   && SQLITE_OK!=(rc = subjournalPageIfRequired(pPg))
+  ){
+    return rc;
+  }
+
+  PAGERTRACE(("MOVE %d page %d (needSync=%d) moves to %d\n", 
+      PAGERID(pPager), pPg->pgno, (pPg->flags&PGHDR_NEED_SYNC)?1:0, pgno));
+  IOTRACE(("MOVE %p %d %d\n", pPager, pPg->pgno, pgno))
+
+  /* If the journal needs to be sync()ed before page pPg->pgno can
+  ** be written to, store pPg->pgno in local variable needSyncPgno.
+  **
+  ** If the isCommit flag is set, there is no need to remember that
+  ** the journal needs to be sync()ed before database page pPg->pgno 
+  ** can be written to. The caller has already promised not to write to it.
+  */
+  if( (pPg->flags&PGHDR_NEED_SYNC) && !isCommit ){
+    needSyncPgno = pPg->pgno;
+    assert( pPager->journalMode==PAGER_JOURNALMODE_OFF ||
+            pageInJournal(pPager, pPg) || pPg->pgno>pPager->dbOrigSize );
+    assert( pPg->flags&PGHDR_DIRTY );
+  }
+
+  /* If the cache contains a page with page-number pgno, remove it
+  ** from its hash chain. Also, if the PGHDR_NEED_SYNC flag was set for 
+  ** page pgno before the 'move' operation, it needs to be retained 
+  ** for the page moved there.
+  */
+  pPg->flags &= ~PGHDR_NEED_SYNC;
+  pPgOld = sqlite3PagerLookup(pPager, pgno);
+  assert( !pPgOld || pPgOld->nRef==1 );
+  if( pPgOld ){
+    pPg->flags |= (pPgOld->flags&PGHDR_NEED_SYNC);
+    if( pPager->tempFile ){
+      /* Do not discard pages from an in-memory database since we might
+      ** need to rollback later.  Just move the page out of the way. */
+      sqlite3PcacheMove(pPgOld, pPager->dbSize+1);
+    }else{
+      sqlite3PcacheDrop(pPgOld);
+    }
+  }
+
+  origPgno = pPg->pgno;
+  sqlite3PcacheMove(pPg, pgno);
+  sqlite3PcacheMakeDirty(pPg);
+
+  /* For an in-memory database, make sure the original page continues
+  ** to exist, in case the transaction needs to roll back.  Use pPgOld
+  ** as the original page since it has already been allocated.
+  */
+  if( pPager->tempFile && pPgOld ){
+    sqlite3PcacheMove(pPgOld, origPgno);
+    sqlite3PagerUnrefNotNull(pPgOld);
+  }
+
+  if( needSyncPgno ){
+    /* If needSyncPgno is non-zero, then the journal file needs to be 
+    ** sync()ed before any data is written to database file page needSyncPgno.
+    ** Currently, no such page exists in the page-cache and the 
+    ** "is journaled" bitvec flag has been set. This needs to be remedied by
+    ** loading the page into the pager-cache and setting the PGHDR_NEED_SYNC
+    ** flag.
+    **
+    ** If the attempt to load the page into the page-cache fails, (due
+    ** to a malloc() or IO failure), clear the bit in the pInJournal[]
+    ** array. Otherwise, if the page is loaded and written again in
+    ** this transaction, it may be written to the database file before
+    ** it is synced into the journal file. This way, it may end up in
+    ** the journal file twice, but that is not a problem.
+    */
+    PgHdr *pPgHdr;
+    rc = sqlite3PagerGet(pPager, needSyncPgno, &pPgHdr, 0);
+    if( rc!=SQLITE_OK ){
+      if( needSyncPgno<=pPager->dbOrigSize ){
+        assert( pPager->pTmpSpace!=0 );
+        sqlite3BitvecClear(pPager->pInJournal, needSyncPgno, pPager->pTmpSpace);
+      }
+      return rc;
+    }
+    pPgHdr->flags |= PGHDR_NEED_SYNC;
+    sqlite3PcacheMakeDirty(pPgHdr);
+    sqlite3PagerUnrefNotNull(pPgHdr);
+  }
+
+  return SQLITE_OK;
+}
+#endif
+
+/*
+** The page handle passed as the first argument refers to a dirty page 
+** with a page number other than iNew. This function changes the page's 
+** page number to iNew and sets the value of the PgHdr.flags field to 
+** the value passed as the third parameter.
+*/
+SQLITE_PRIVATE void sqlite3PagerRekey(DbPage *pPg, Pgno iNew, u16 flags){
+  assert( pPg->pgno!=iNew );
+  pPg->flags = flags;
+  sqlite3PcacheMove(pPg, iNew);
+}
+
+/*
+** Return a pointer to the data for the specified page.
+*/
+SQLITE_PRIVATE void *sqlite3PagerGetData(DbPage *pPg){
+  assert( pPg->nRef>0 || pPg->pPager->memDb );
+  return pPg->pData;
+}
+
+/*
+** Return a pointer to the Pager.nExtra bytes of "extra" space 
+** allocated along with the specified page.
+*/
+SQLITE_PRIVATE void *sqlite3PagerGetExtra(DbPage *pPg){
+  return pPg->pExtra;
+}
+
+/*
+** Get/set the locking-mode for this pager. Parameter eMode must be one
+** of PAGER_LOCKINGMODE_QUERY, PAGER_LOCKINGMODE_NORMAL or 
+** PAGER_LOCKINGMODE_EXCLUSIVE. If the parameter is not _QUERY, then
+** the locking-mode is set to the value specified.
+**
+** The returned value is either PAGER_LOCKINGMODE_NORMAL or
+** PAGER_LOCKINGMODE_EXCLUSIVE, indicating the current (possibly updated)
+** locking-mode.
+*/
+SQLITE_PRIVATE int sqlite3PagerLockingMode(Pager *pPager, int eMode){
+  assert( eMode==PAGER_LOCKINGMODE_QUERY
+            || eMode==PAGER_LOCKINGMODE_NORMAL
+            || eMode==PAGER_LOCKINGMODE_EXCLUSIVE );
+  assert( PAGER_LOCKINGMODE_QUERY<0 );
+  assert( PAGER_LOCKINGMODE_NORMAL>=0 && PAGER_LOCKINGMODE_EXCLUSIVE>=0 );
+  assert( pPager->exclusiveMode || 0==sqlite3WalHeapMemory(pPager->pWal) );
+  if( eMode>=0 && !pPager->tempFile && !sqlite3WalHeapMemory(pPager->pWal) ){
+    pPager->exclusiveMode = (u8)eMode;
+  }
+  return (int)pPager->exclusiveMode;
+}
+
+/*
+** Set the journal-mode for this pager. Parameter eMode must be one of:
+**
+**    PAGER_JOURNALMODE_DELETE
+**    PAGER_JOURNALMODE_TRUNCATE
+**    PAGER_JOURNALMODE_PERSIST
+**    PAGER_JOURNALMODE_OFF
+**    PAGER_JOURNALMODE_MEMORY
+**    PAGER_JOURNALMODE_WAL
+**
+** The journalmode is set to the value specified if the change is allowed.
+** The change may be disallowed for the following reasons:
+**
+**   *  An in-memory database can only have its journal_mode set to _OFF
+**      or _MEMORY.
+**
+**   *  Temporary databases cannot have _WAL journalmode.
+**
+** The returned indicate the current (possibly updated) journal-mode.
+*/
+SQLITE_PRIVATE int sqlite3PagerSetJournalMode(Pager *pPager, int eMode){
+  u8 eOld = pPager->journalMode;    /* Prior journalmode */
+
+#ifdef SQLITE_DEBUG
+  /* The print_pager_state() routine is intended to be used by the debugger
+  ** only.  We invoke it once here to suppress a compiler warning. */
+  print_pager_state(pPager);
+#endif
+
+
+  /* The eMode parameter is always valid */
+  assert(      eMode==PAGER_JOURNALMODE_DELETE
+            || eMode==PAGER_JOURNALMODE_TRUNCATE
+            || eMode==PAGER_JOURNALMODE_PERSIST
+            || eMode==PAGER_JOURNALMODE_OFF 
+            || eMode==PAGER_JOURNALMODE_WAL 
+            || eMode==PAGER_JOURNALMODE_MEMORY );
+
+  /* This routine is only called from the OP_JournalMode opcode, and
+  ** the logic there will never allow a temporary file to be changed
+  ** to WAL mode.
+  */
+  assert( pPager->tempFile==0 || eMode!=PAGER_JOURNALMODE_WAL );
+
+  /* Do allow the journalmode of an in-memory database to be set to
+  ** anything other than MEMORY or OFF
+  */
+  if( MEMDB ){
+    assert( eOld==PAGER_JOURNALMODE_MEMORY || eOld==PAGER_JOURNALMODE_OFF );
+    if( eMode!=PAGER_JOURNALMODE_MEMORY && eMode!=PAGER_JOURNALMODE_OFF ){
+      eMode = eOld;
+    }
+  }
+
+  if( eMode!=eOld ){
+
+    /* Change the journal mode. */
+    assert( pPager->eState!=PAGER_ERROR );
+    pPager->journalMode = (u8)eMode;
+
+    /* When transistioning from TRUNCATE or PERSIST to any other journal
+    ** mode except WAL, unless the pager is in locking_mode=exclusive mode,
+    ** delete the journal file.
+    */
+    assert( (PAGER_JOURNALMODE_TRUNCATE & 5)==1 );
+    assert( (PAGER_JOURNALMODE_PERSIST & 5)==1 );
+    assert( (PAGER_JOURNALMODE_DELETE & 5)==0 );
+    assert( (PAGER_JOURNALMODE_MEMORY & 5)==4 );
+    assert( (PAGER_JOURNALMODE_OFF & 5)==0 );
+    assert( (PAGER_JOURNALMODE_WAL & 5)==5 );
+
+    assert( isOpen(pPager->fd) || pPager->exclusiveMode );
+    if( !pPager->exclusiveMode && (eOld & 5)==1 && (eMode & 1)==0 ){
+
+      /* In this case we would like to delete the journal file. If it is
+      ** not possible, then that is not a problem. Deleting the journal file
+      ** here is an optimization only.
+      **
+      ** Before deleting the journal file, obtain a RESERVED lock on the
+      ** database file. This ensures that the journal file is not deleted
+      ** while it is in use by some other client.
+      */
+      sqlite3OsClose(pPager->jfd);
+      if( pPager->eLock>=RESERVED_LOCK ){
+        sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
+      }else{
+        int rc = SQLITE_OK;
+        int state = pPager->eState;
+        assert( state==PAGER_OPEN || state==PAGER_READER );
+        if( state==PAGER_OPEN ){
+          rc = sqlite3PagerSharedLock(pPager);
+        }
+        if( pPager->eState==PAGER_READER ){
+          assert( rc==SQLITE_OK );
+          rc = pagerLockDb(pPager, RESERVED_LOCK);
+        }
+        if( rc==SQLITE_OK ){
+          sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
+        }
+        if( rc==SQLITE_OK && state==PAGER_READER ){
+          pagerUnlockDb(pPager, SHARED_LOCK);
+        }else if( state==PAGER_OPEN ){
+          pager_unlock(pPager);
+        }
+        assert( state==pPager->eState );
+      }
+    }else if( eMode==PAGER_JOURNALMODE_OFF ){
+      sqlite3OsClose(pPager->jfd);
+    }
+  }
+
+  /* Return the new journal mode */
+  return (int)pPager->journalMode;
+}
+
+/*
+** Return the current journal mode.
+*/
+SQLITE_PRIVATE int sqlite3PagerGetJournalMode(Pager *pPager){
+  return (int)pPager->journalMode;
+}
+
+/*
+** Return TRUE if the pager is in a state where it is OK to change the
+** journalmode.  Journalmode changes can only happen when the database
+** is unmodified.
+*/
+SQLITE_PRIVATE int sqlite3PagerOkToChangeJournalMode(Pager *pPager){
+  assert( assert_pager_state(pPager) );
+  if( pPager->eState>=PAGER_WRITER_CACHEMOD ) return 0;
+  if( NEVER(isOpen(pPager->jfd) && pPager->journalOff>0) ) return 0;
+  return 1;
+}
+
+/*
+** Get/set the size-limit used for persistent journal files.
+**
+** Setting the size limit to -1 means no limit is enforced.
+** An attempt to set a limit smaller than -1 is a no-op.
+*/
+SQLITE_PRIVATE i64 sqlite3PagerJournalSizeLimit(Pager *pPager, i64 iLimit){
+  if( iLimit>=-1 ){
+    pPager->journalSizeLimit = iLimit;
+    sqlite3WalLimit(pPager->pWal, iLimit);
+  }
+  return pPager->journalSizeLimit;
+}
+
+/*
+** Return a pointer to the pPager->pBackup variable. The backup module
+** in backup.c maintains the content of this variable. This module
+** uses it opaquely as an argument to sqlite3BackupRestart() and
+** sqlite3BackupUpdate() only.
+*/
+SQLITE_PRIVATE sqlite3_backup **sqlite3PagerBackupPtr(Pager *pPager){
+  return &pPager->pBackup;
+}
+
+#ifndef SQLITE_OMIT_VACUUM
+/*
+** Unless this is an in-memory or temporary database, clear the pager cache.
+*/
+SQLITE_PRIVATE void sqlite3PagerClearCache(Pager *pPager){
+  assert( MEMDB==0 || pPager->tempFile );
+  if( pPager->tempFile==0 ) pager_reset(pPager);
+}
+#endif
+
+
+#ifndef SQLITE_OMIT_WAL
+/*
+** This function is called when the user invokes "PRAGMA wal_checkpoint",
+** "PRAGMA wal_blocking_checkpoint" or calls the sqlite3_wal_checkpoint()
+** or wal_blocking_checkpoint() API functions.
+**
+** Parameter eMode is one of SQLITE_CHECKPOINT_PASSIVE, FULL or RESTART.
+*/
+SQLITE_PRIVATE int sqlite3PagerCheckpoint(Pager *pPager, int eMode, int *pnLog, int *pnCkpt){
+  int rc = SQLITE_OK;
+  if( pPager->pWal ){
+    rc = sqlite3WalCheckpoint(pPager->pWal, eMode,
+        (eMode==SQLITE_CHECKPOINT_PASSIVE ? 0 : pPager->xBusyHandler),
+        pPager->pBusyHandlerArg,
+        pPager->ckptSyncFlags, pPager->pageSize, (u8 *)pPager->pTmpSpace,
+        pnLog, pnCkpt
+    );
+  }
+  return rc;
+}
+
+SQLITE_PRIVATE int sqlite3PagerWalCallback(Pager *pPager){
+  return sqlite3WalCallback(pPager->pWal);
+}
+
+/*
+** Return true if the underlying VFS for the given pager supports the
+** primitives necessary for write-ahead logging.
+*/
+SQLITE_PRIVATE int sqlite3PagerWalSupported(Pager *pPager){
+  const sqlite3_io_methods *pMethods = pPager->fd->pMethods;
+  if( pPager->noLock ) return 0;
+  return pPager->exclusiveMode || (pMethods->iVersion>=2 && pMethods->xShmMap);
+}
+
+/*
+** Attempt to take an exclusive lock on the database file. If a PENDING lock
+** is obtained instead, immediately release it.
+*/
+static int pagerExclusiveLock(Pager *pPager){
+  int rc;                         /* Return code */
+
+  assert( pPager->eLock==SHARED_LOCK || pPager->eLock==EXCLUSIVE_LOCK );
+  rc = pagerLockDb(pPager, EXCLUSIVE_LOCK);
+  if( rc!=SQLITE_OK ){
+    /* If the attempt to grab the exclusive lock failed, release the 
+    ** pending lock that may have been obtained instead.  */
+    pagerUnlockDb(pPager, SHARED_LOCK);
+  }
+
+  return rc;
+}
+
+/*
+** Call sqlite3WalOpen() to open the WAL handle. If the pager is in 
+** exclusive-locking mode when this function is called, take an EXCLUSIVE
+** lock on the database file and use heap-memory to store the wal-index
+** in. Otherwise, use the normal shared-memory.
+*/
+static int pagerOpenWal(Pager *pPager){
+  int rc = SQLITE_OK;
+
+  assert( pPager->pWal==0 && pPager->tempFile==0 );
+  assert( pPager->eLock==SHARED_LOCK || pPager->eLock==EXCLUSIVE_LOCK );
+
+  /* If the pager is already in exclusive-mode, the WAL module will use 
+  ** heap-memory for the wal-index instead of the VFS shared-memory 
+  ** implementation. Take the exclusive lock now, before opening the WAL
+  ** file, to make sure this is safe.
+  */
+  if( pPager->exclusiveMode ){
+    rc = pagerExclusiveLock(pPager);
+  }
+
+  /* Open the connection to the log file. If this operation fails, 
+  ** (e.g. due to malloc() failure), return an error code.
+  */
+  if( rc==SQLITE_OK ){
+    rc = sqlite3WalOpen(pPager->pVfs,
+        pPager->fd, pPager->zWal, pPager->exclusiveMode,
+        pPager->journalSizeLimit, &pPager->pWal
+    );
+  }
+  pagerFixMaplimit(pPager);
+
+  return rc;
+}
+
+
+/*
+** The caller must be holding a SHARED lock on the database file to call
+** this function.
+**
+** If the pager passed as the first argument is open on a real database
+** file (not a temp file or an in-memory database), and the WAL file
+** is not already open, make an attempt to open it now. If successful,
+** return SQLITE_OK. If an error occurs or the VFS used by the pager does 
+** not support the xShmXXX() methods, return an error code. *pbOpen is
+** not modified in either case.
+**
+** If the pager is open on a temp-file (or in-memory database), or if
+** the WAL file is already open, set *pbOpen to 1 and return SQLITE_OK
+** without doing anything.
+*/
+SQLITE_PRIVATE int sqlite3PagerOpenWal(
+  Pager *pPager,                  /* Pager object */
+  int *pbOpen                     /* OUT: Set to true if call is a no-op */
+){
+  int rc = SQLITE_OK;             /* Return code */
+
+  assert( assert_pager_state(pPager) );
+  assert( pPager->eState==PAGER_OPEN   || pbOpen );
+  assert( pPager->eState==PAGER_READER || !pbOpen );
+  assert( pbOpen==0 || *pbOpen==0 );
+  assert( pbOpen!=0 || (!pPager->tempFile && !pPager->pWal) );
+
+  if( !pPager->tempFile && !pPager->pWal ){
+    if( !sqlite3PagerWalSupported(pPager) ) return SQLITE_CANTOPEN;
+
+    /* Close any rollback journal previously open */
+    sqlite3OsClose(pPager->jfd);
+
+    rc = pagerOpenWal(pPager);
+    if( rc==SQLITE_OK ){
+      pPager->journalMode = PAGER_JOURNALMODE_WAL;
+      pPager->eState = PAGER_OPEN;
+    }
+  }else{
+    *pbOpen = 1;
+  }
+
+  return rc;
+}
+
+/*
+** This function is called to close the connection to the log file prior
+** to switching from WAL to rollback mode.
+**
+** Before closing the log file, this function attempts to take an 
+** EXCLUSIVE lock on the database file. If this cannot be obtained, an
+** error (SQLITE_BUSY) is returned and the log connection is not closed.
+** If successful, the EXCLUSIVE lock is not released before returning.
+*/
+SQLITE_PRIVATE int sqlite3PagerCloseWal(Pager *pPager){
+  int rc = SQLITE_OK;
+
+  assert( pPager->journalMode==PAGER_JOURNALMODE_WAL );
+
+  /* If the log file is not already open, but does exist in the file-system,
+  ** it may need to be checkpointed before the connection can switch to
+  ** rollback mode. Open it now so this can happen.
+  */
+  if( !pPager->pWal ){
+    int logexists = 0;
+    rc = pagerLockDb(pPager, SHARED_LOCK);
+    if( rc==SQLITE_OK ){
+      rc = sqlite3OsAccess(
+          pPager->pVfs, pPager->zWal, SQLITE_ACCESS_EXISTS, &logexists
+      );
+    }
+    if( rc==SQLITE_OK && logexists ){
+      rc = pagerOpenWal(pPager);
+    }
+  }
+    
+  /* Checkpoint and close the log. Because an EXCLUSIVE lock is held on
+  ** the database file, the log and log-summary files will be deleted.
+  */
+  if( rc==SQLITE_OK && pPager->pWal ){
+    rc = pagerExclusiveLock(pPager);
+    if( rc==SQLITE_OK ){
+      rc = sqlite3WalClose(pPager->pWal, pPager->ckptSyncFlags,
+                           pPager->pageSize, (u8*)pPager->pTmpSpace);
+      pPager->pWal = 0;
+      pagerFixMaplimit(pPager);
+      if( rc && !pPager->exclusiveMode ) pagerUnlockDb(pPager, SHARED_LOCK);
+    }
+  }
+  return rc;
+}
+
+#ifdef SQLITE_ENABLE_SNAPSHOT
+/*
+** If this is a WAL database, obtain a snapshot handle for the snapshot
+** currently open. Otherwise, return an error.
+*/
+SQLITE_PRIVATE int sqlite3PagerSnapshotGet(Pager *pPager, sqlite3_snapshot **ppSnapshot){
+  int rc = SQLITE_ERROR;
+  if( pPager->pWal ){
+    rc = sqlite3WalSnapshotGet(pPager->pWal, ppSnapshot);
+  }
+  return rc;
+}
+
+/*
+** If this is a WAL database, store a pointer to pSnapshot. Next time a
+** read transaction is opened, attempt to read from the snapshot it 
+** identifies. If this is not a WAL database, return an error.
+*/
+SQLITE_PRIVATE int sqlite3PagerSnapshotOpen(Pager *pPager, sqlite3_snapshot *pSnapshot){
+  int rc = SQLITE_OK;
+  if( pPager->pWal ){
+    sqlite3WalSnapshotOpen(pPager->pWal, pSnapshot);
+  }else{
+    rc = SQLITE_ERROR;
+  }
+  return rc;
+}
+#endif /* SQLITE_ENABLE_SNAPSHOT */
+#endif /* !SQLITE_OMIT_WAL */
+
+#ifdef SQLITE_ENABLE_ZIPVFS
+/*
+** A read-lock must be held on the pager when this function is called. If
+** the pager is in WAL mode and the WAL file currently contains one or more
+** frames, return the size in bytes of the page images stored within the
+** WAL frames. Otherwise, if this is not a WAL database or the WAL file
+** is empty, return 0.
+*/
+SQLITE_PRIVATE int sqlite3PagerWalFramesize(Pager *pPager){
+  assert( pPager->eState>=PAGER_READER );
+  return sqlite3WalFramesize(pPager->pWal);
+}
+#endif
+
+#endif /* SQLITE_OMIT_DISKIO */
+
+/* BEGIN SQLCIPHER */
+#ifdef SQLITE_HAS_CODEC
+SQLITE_API void sqlite3pager_get_codec(Pager *pPager, void **ctx) {
+  *ctx = pPager->pCodec;
+}
+
+SQLITE_API int sqlite3pager_is_mj_pgno(Pager *pPager, Pgno pgno) {
+  return (PAGER_MJ_PGNO(pPager) == pgno) ? 1 : 0;
+}
+
+SQLITE_PRIVATE sqlite3_file *sqlite3Pager_get_fd(Pager *pPager) {
+  return (isOpen(pPager->fd)) ? pPager->fd : NULL;
+}
+
+SQLITE_API void sqlite3pager_sqlite3PagerSetCodec(
+  Pager *pPager,
+  void *(*xCodec)(void*,void*,Pgno,int),
+  void (*xCodecSizeChng)(void*,int,int),
+  void (*xCodecFree)(void*),
+  void *pCodec
+){
+  sqlite3PagerSetCodec(pPager, xCodec, xCodecSizeChng, xCodecFree, pCodec); 
+}
+
+SQLITE_API void sqlite3pager_sqlite3PagerSetError( Pager *pPager, int error) {
+  pPager->errCode = error;
+}
+
+#endif
+/* END SQLCIPHER */
+
+
+/************** End of pager.c ***********************************************/
+/************** Begin file wal.c *********************************************/
+/*
+** 2010 February 1
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains the implementation of a write-ahead log (WAL) used in 
+** "journal_mode=WAL" mode.
+**
+** WRITE-AHEAD LOG (WAL) FILE FORMAT
+**
+** A WAL file consists of a header followed by zero or more "frames".
+** Each frame records the revised content of a single page from the
+** database file.  All changes to the database are recorded by writing
+** frames into the WAL.  Transactions commit when a frame is written that
+** contains a commit marker.  A single WAL can and usually does record 
+** multiple transactions.  Periodically, the content of the WAL is
+** transferred back into the database file in an operation called a
+** "checkpoint".
+**
+** A single WAL file can be used multiple times.  In other words, the
+** WAL can fill up with frames and then be checkpointed and then new
+** frames can overwrite the old ones.  A WAL always grows from beginning
+** toward the end.  Checksums and counters attached to each frame are
+** used to determine which frames within the WAL are valid and which
+** are leftovers from prior checkpoints.
+**
+** The WAL header is 32 bytes in size and consists of the following eight
+** big-endian 32-bit unsigned integer values:
+**
+**     0: Magic number.  0x377f0682 or 0x377f0683
+**     4: File format version.  Currently 3007000
+**     8: Database page size.  Example: 1024
+**    12: Checkpoint sequence number
+**    16: Salt-1, random integer incremented with each checkpoint
+**    20: Salt-2, a different random integer changing with each ckpt
+**    24: Checksum-1 (first part of checksum for first 24 bytes of header).
+**    28: Checksum-2 (second part of checksum for first 24 bytes of header).
+**
+** Immediately following the wal-header are zero or more frames. Each
+** frame consists of a 24-byte frame-header followed by a <page-size> bytes
+** of page data. The frame-header is six big-endian 32-bit unsigned 
+** integer values, as follows:
+**
+**     0: Page number.
+**     4: For commit records, the size of the database image in pages 
+**        after the commit. For all other records, zero.
+**     8: Salt-1 (copied from the header)
+**    12: Salt-2 (copied from the header)
+**    16: Checksum-1.
+**    20: Checksum-2.
+**
+** A frame is considered valid if and only if the following conditions are
+** true:
+**
+**    (1) The salt-1 and salt-2 values in the frame-header match
+**        salt values in the wal-header
+**
+**    (2) The checksum values in the final 8 bytes of the frame-header
+**        exactly match the checksum computed consecutively on the
+**        WAL header and the first 8 bytes and the content of all frames
+**        up to and including the current frame.
+**
+** The checksum is computed using 32-bit big-endian integers if the
+** magic number in the first 4 bytes of the WAL is 0x377f0683 and it
+** is computed using little-endian if the magic number is 0x377f0682.
+** The checksum values are always stored in the frame header in a
+** big-endian format regardless of which byte order is used to compute
+** the checksum.  The checksum is computed by interpreting the input as
+** an even number of unsigned 32-bit integers: x[0] through x[N].  The
+** algorithm used for the checksum is as follows:
+** 
+**   for i from 0 to n-1 step 2:
+**     s0 += x[i] + s1;
+**     s1 += x[i+1] + s0;
+**   endfor
+**
+** Note that s0 and s1 are both weighted checksums using fibonacci weights
+** in reverse order (the largest fibonacci weight occurs on the first element
+** of the sequence being summed.)  The s1 value spans all 32-bit 
+** terms of the sequence whereas s0 omits the final term.
+**
+** On a checkpoint, the WAL is first VFS.xSync-ed, then valid content of the
+** WAL is transferred into the database, then the database is VFS.xSync-ed.
+** The VFS.xSync operations serve as write barriers - all writes launched
+** before the xSync must complete before any write that launches after the
+** xSync begins.
+**
+** After each checkpoint, the salt-1 value is incremented and the salt-2
+** value is randomized.  This prevents old and new frames in the WAL from
+** being considered valid at the same time and being checkpointing together
+** following a crash.
+**
+** READER ALGORITHM
+**
+** To read a page from the database (call it page number P), a reader
+** first checks the WAL to see if it contains page P.  If so, then the
+** last valid instance of page P that is a followed by a commit frame
+** or is a commit frame itself becomes the value read.  If the WAL
+** contains no copies of page P that are valid and which are a commit
+** frame or are followed by a commit frame, then page P is read from
+** the database file.
+**
+** To start a read transaction, the reader records the index of the last
+** valid frame in the WAL.  The reader uses this recorded "mxFrame" value
+** for all subsequent read operations.  New transactions can be appended
+** to the WAL, but as long as the reader uses its original mxFrame value
+** and ignores the newly appended content, it will see a consistent snapshot
+** of the database from a single point in time.  This technique allows
+** multiple concurrent readers to view different versions of the database
+** content simultaneously.
+**
+** The reader algorithm in the previous paragraphs works correctly, but 
+** because frames for page P can appear anywhere within the WAL, the
+** reader has to scan the entire WAL looking for page P frames.  If the
+** WAL is large (multiple megabytes is typical) that scan can be slow,
+** and read performance suffers.  To overcome this problem, a separate
+** data structure called the wal-index is maintained to expedite the
+** search for frames of a particular page.
+** 
+** WAL-INDEX FORMAT
+**
+** Conceptually, the wal-index is shared memory, though VFS implementations
+** might choose to implement the wal-index using a mmapped file.  Because
+** the wal-index is shared memory, SQLite does not support journal_mode=WAL 
+** on a network filesystem.  All users of the database must be able to
+** share memory.
+**
+** The wal-index is transient.  After a crash, the wal-index can (and should
+** be) reconstructed from the original WAL file.  In fact, the VFS is required
+** to either truncate or zero the header of the wal-index when the last
+** connection to it closes.  Because the wal-index is transient, it can
+** use an architecture-specific format; it does not have to be cross-platform.
+** Hence, unlike the database and WAL file formats which store all values
+** as big endian, the wal-index can store multi-byte values in the native
+** byte order of the host computer.
+**
+** The purpose of the wal-index is to answer this question quickly:  Given
+** a page number P and a maximum frame index M, return the index of the 
+** last frame in the wal before frame M for page P in the WAL, or return
+** NULL if there are no frames for page P in the WAL prior to M.
+**
+** The wal-index consists of a header region, followed by an one or
+** more index blocks.  
+**
+** The wal-index header contains the total number of frames within the WAL
+** in the mxFrame field.
+**
+** Each index block except for the first contains information on 
+** HASHTABLE_NPAGE frames. The first index block contains information on
+** HASHTABLE_NPAGE_ONE frames. The values of HASHTABLE_NPAGE_ONE and 
+** HASHTABLE_NPAGE are selected so that together the wal-index header and
+** first index block are the same size as all other index blocks in the
+** wal-index.
+**
+** Each index block contains two sections, a page-mapping that contains the
+** database page number associated with each wal frame, and a hash-table 
+** that allows readers to query an index block for a specific page number.
+** The page-mapping is an array of HASHTABLE_NPAGE (or HASHTABLE_NPAGE_ONE
+** for the first index block) 32-bit page numbers. The first entry in the 
+** first index-block contains the database page number corresponding to the
+** first frame in the WAL file. The first entry in the second index block
+** in the WAL file corresponds to the (HASHTABLE_NPAGE_ONE+1)th frame in
+** the log, and so on.
+**
+** The last index block in a wal-index usually contains less than the full
+** complement of HASHTABLE_NPAGE (or HASHTABLE_NPAGE_ONE) page-numbers,
+** depending on the contents of the WAL file. This does not change the
+** allocated size of the page-mapping array - the page-mapping array merely
+** contains unused entries.
+**
+** Even without using the hash table, the last frame for page P
+** can be found by scanning the page-mapping sections of each index block
+** starting with the last index block and moving toward the first, and
+** within each index block, starting at the end and moving toward the
+** beginning.  The first entry that equals P corresponds to the frame
+** holding the content for that page.
+**
+** The hash table consists of HASHTABLE_NSLOT 16-bit unsigned integers.
+** HASHTABLE_NSLOT = 2*HASHTABLE_NPAGE, and there is one entry in the
+** hash table for each page number in the mapping section, so the hash 
+** table is never more than half full.  The expected number of collisions 
+** prior to finding a match is 1.  Each entry of the hash table is an
+** 1-based index of an entry in the mapping section of the same
+** index block.   Let K be the 1-based index of the largest entry in
+** the mapping section.  (For index blocks other than the last, K will
+** always be exactly HASHTABLE_NPAGE (4096) and for the last index block
+** K will be (mxFrame%HASHTABLE_NPAGE).)  Unused slots of the hash table
+** contain a value of 0.
+**
+** To look for page P in the hash table, first compute a hash iKey on
+** P as follows:
+**
+**      iKey = (P * 383) % HASHTABLE_NSLOT
+**
+** Then start scanning entries of the hash table, starting with iKey
+** (wrapping around to the beginning when the end of the hash table is
+** reached) until an unused hash slot is found. Let the first unused slot
+** be at index iUnused.  (iUnused might be less than iKey if there was
+** wrap-around.) Because the hash table is never more than half full,
+** the search is guaranteed to eventually hit an unused entry.  Let 
+** iMax be the value between iKey and iUnused, closest to iUnused,
+** where aHash[iMax]==P.  If there is no iMax entry (if there exists
+** no hash slot such that aHash[i]==p) then page P is not in the
+** current index block.  Otherwise the iMax-th mapping entry of the
+** current index block corresponds to the last entry that references 
+** page P.
+**
+** A hash search begins with the last index block and moves toward the
+** first index block, looking for entries corresponding to page P.  On
+** average, only two or three slots in each index block need to be
+** examined in order to either find the last entry for page P, or to
+** establish that no such entry exists in the block.  Each index block
+** holds over 4000 entries.  So two or three index blocks are sufficient
+** to cover a typical 10 megabyte WAL file, assuming 1K pages.  8 or 10
+** comparisons (on average) suffice to either locate a frame in the
+** WAL or to establish that the frame does not exist in the WAL.  This
+** is much faster than scanning the entire 10MB WAL.
+**
+** Note that entries are added in order of increasing K.  Hence, one
+** reader might be using some value K0 and a second reader that started
+** at a later time (after additional transactions were added to the WAL
+** and to the wal-index) might be using a different value K1, where K1>K0.
+** Both readers can use the same hash table and mapping section to get
+** the correct result.  There may be entries in the hash table with
+** K>K0 but to the first reader, those entries will appear to be unused
+** slots in the hash table and so the first reader will get an answer as
+** if no values greater than K0 had ever been inserted into the hash table
+** in the first place - which is what reader one wants.  Meanwhile, the
+** second reader using K1 will see additional values that were inserted
+** later, which is exactly what reader two wants.  
+**
+** When a rollback occurs, the value of K is decreased. Hash table entries
+** that correspond to frames greater than the new K value are removed
+** from the hash table at this point.
+*/
+#ifndef SQLITE_OMIT_WAL
+
+/* #include "wal.h" */
+
+/*
+** Trace output macros
+*/
+#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
+SQLITE_PRIVATE int sqlite3WalTrace = 0;
+# define WALTRACE(X)  if(sqlite3WalTrace) sqlite3DebugPrintf X
+#else
+# define WALTRACE(X)
+#endif
+
+/*
+** The maximum (and only) versions of the wal and wal-index formats
+** that may be interpreted by this version of SQLite.
+**
+** If a client begins recovering a WAL file and finds that (a) the checksum
+** values in the wal-header are correct and (b) the version field is not
+** WAL_MAX_VERSION, recovery fails and SQLite returns SQLITE_CANTOPEN.
+**
+** Similarly, if a client successfully reads a wal-index header (i.e. the 
+** checksum test is successful) and finds that the version field is not
+** WALINDEX_MAX_VERSION, then no read-transaction is opened and SQLite
+** returns SQLITE_CANTOPEN.
+*/
+#define WAL_MAX_VERSION      3007000
+#define WALINDEX_MAX_VERSION 3007000
+
+/*
+** Indices of various locking bytes.   WAL_NREADER is the number
+** of available reader locks and should be at least 3.  The default
+** is SQLITE_SHM_NLOCK==8 and  WAL_NREADER==5.
+*/
+#define WAL_WRITE_LOCK         0
+#define WAL_ALL_BUT_WRITE      1
+#define WAL_CKPT_LOCK          1
+#define WAL_RECOVER_LOCK       2
+#define WAL_READ_LOCK(I)       (3+(I))
+#define WAL_NREADER            (SQLITE_SHM_NLOCK-3)
+
+
+/* Object declarations */
+typedef struct WalIndexHdr WalIndexHdr;
+typedef struct WalIterator WalIterator;
+typedef struct WalCkptInfo WalCkptInfo;
+
+
+/*
+** The following object holds a copy of the wal-index header content.
+**
+** The actual header in the wal-index consists of two copies of this
+** object followed by one instance of the WalCkptInfo object.
+** For all versions of SQLite through 3.10.0 and probably beyond,
+** the locking bytes (WalCkptInfo.aLock) start at offset 120 and
+** the total header size is 136 bytes.
+**
+** The szPage value can be any power of 2 between 512 and 32768, inclusive.
+** Or it can be 1 to represent a 65536-byte page.  The latter case was
+** added in 3.7.1 when support for 64K pages was added.  
+*/
+struct WalIndexHdr {
+  u32 iVersion;                   /* Wal-index version */
+  u32 unused;                     /* Unused (padding) field */
+  u32 iChange;                    /* Counter incremented each transaction */
+  u8 isInit;                      /* 1 when initialized */
+  u8 bigEndCksum;                 /* True if checksums in WAL are big-endian */
+  u16 szPage;                     /* Database page size in bytes. 1==64K */
+  u32 mxFrame;                    /* Index of last valid frame in the WAL */
+  u32 nPage;                      /* Size of database in pages */
+  u32 aFrameCksum[2];             /* Checksum of last frame in log */
+  u32 aSalt[2];                   /* Two salt values copied from WAL header */
+  u32 aCksum[2];                  /* Checksum over all prior fields */
+};
+
+/*
+** A copy of the following object occurs in the wal-index immediately
+** following the second copy of the WalIndexHdr.  This object stores
+** information used by checkpoint.
+**
+** nBackfill is the number of frames in the WAL that have been written
+** back into the database. (We call the act of moving content from WAL to
+** database "backfilling".)  The nBackfill number is never greater than
+** WalIndexHdr.mxFrame.  nBackfill can only be increased by threads
+** holding the WAL_CKPT_LOCK lock (which includes a recovery thread).
+** However, a WAL_WRITE_LOCK thread can move the value of nBackfill from
+** mxFrame back to zero when the WAL is reset.
+**
+** nBackfillAttempted is the largest value of nBackfill that a checkpoint
+** has attempted to achieve.  Normally nBackfill==nBackfillAtempted, however
+** the nBackfillAttempted is set before any backfilling is done and the
+** nBackfill is only set after all backfilling completes.  So if a checkpoint
+** crashes, nBackfillAttempted might be larger than nBackfill.  The
+** WalIndexHdr.mxFrame must never be less than nBackfillAttempted.
+**
+** The aLock[] field is a set of bytes used for locking.  These bytes should
+** never be read or written.
+**
+** There is one entry in aReadMark[] for each reader lock.  If a reader
+** holds read-lock K, then the value in aReadMark[K] is no greater than
+** the mxFrame for that reader.  The value READMARK_NOT_USED (0xffffffff)
+** for any aReadMark[] means that entry is unused.  aReadMark[0] is 
+** a special case; its value is never used and it exists as a place-holder
+** to avoid having to offset aReadMark[] indexs by one.  Readers holding
+** WAL_READ_LOCK(0) always ignore the entire WAL and read all content
+** directly from the database.
+**
+** The value of aReadMark[K] may only be changed by a thread that
+** is holding an exclusive lock on WAL_READ_LOCK(K).  Thus, the value of
+** aReadMark[K] cannot changed while there is a reader is using that mark
+** since the reader will be holding a shared lock on WAL_READ_LOCK(K).
+**
+** The checkpointer may only transfer frames from WAL to database where
+** the frame numbers are less than or equal to every aReadMark[] that is
+** in use (that is, every aReadMark[j] for which there is a corresponding
+** WAL_READ_LOCK(j)).  New readers (usually) pick the aReadMark[] with the
+** largest value and will increase an unused aReadMark[] to mxFrame if there
+** is not already an aReadMark[] equal to mxFrame.  The exception to the
+** previous sentence is when nBackfill equals mxFrame (meaning that everything
+** in the WAL has been backfilled into the database) then new readers
+** will choose aReadMark[0] which has value 0 and hence such reader will
+** get all their all content directly from the database file and ignore 
+** the WAL.
+**
+** Writers normally append new frames to the end of the WAL.  However,
+** if nBackfill equals mxFrame (meaning that all WAL content has been
+** written back into the database) and if no readers are using the WAL
+** (in other words, if there are no WAL_READ_LOCK(i) where i>0) then
+** the writer will first "reset" the WAL back to the beginning and start
+** writing new content beginning at frame 1.
+**
+** We assume that 32-bit loads are atomic and so no locks are needed in
+** order to read from any aReadMark[] entries.
+*/
+struct WalCkptInfo {
+  u32 nBackfill;                  /* Number of WAL frames backfilled into DB */
+  u32 aReadMark[WAL_NREADER];     /* Reader marks */
+  u8 aLock[SQLITE_SHM_NLOCK];     /* Reserved space for locks */
+  u32 nBackfillAttempted;         /* WAL frames perhaps written, or maybe not */
+  u32 notUsed0;                   /* Available for future enhancements */
+};
+#define READMARK_NOT_USED  0xffffffff
+
+
+/* A block of WALINDEX_LOCK_RESERVED bytes beginning at
+** WALINDEX_LOCK_OFFSET is reserved for locks. Since some systems
+** only support mandatory file-locks, we do not read or write data
+** from the region of the file on which locks are applied.
+*/
+#define WALINDEX_LOCK_OFFSET (sizeof(WalIndexHdr)*2+offsetof(WalCkptInfo,aLock))
+#define WALINDEX_HDR_SIZE    (sizeof(WalIndexHdr)*2+sizeof(WalCkptInfo))
+
+/* Size of header before each frame in wal */
+#define WAL_FRAME_HDRSIZE 24
+
+/* Size of write ahead log header, including checksum. */
+/* #define WAL_HDRSIZE 24 */
+#define WAL_HDRSIZE 32
+
+/* WAL magic value. Either this value, or the same value with the least
+** significant bit also set (WAL_MAGIC | 0x00000001) is stored in 32-bit
+** big-endian format in the first 4 bytes of a WAL file.
+**
+** If the LSB is set, then the checksums for each frame within the WAL
+** file are calculated by treating all data as an array of 32-bit 
+** big-endian words. Otherwise, they are calculated by interpreting 
+** all data as 32-bit little-endian words.
+*/
+#define WAL_MAGIC 0x377f0682
+
+/*
+** Return the offset of frame iFrame in the write-ahead log file, 
+** assuming a database page size of szPage bytes. The offset returned
+** is to the start of the write-ahead log frame-header.
+*/
+#define walFrameOffset(iFrame, szPage) (                               \
+  WAL_HDRSIZE + ((iFrame)-1)*(i64)((szPage)+WAL_FRAME_HDRSIZE)         \
+)
+
+/*
+** An open write-ahead log file is represented by an instance of the
+** following object.
+*/
+struct Wal {
+  sqlite3_vfs *pVfs;         /* The VFS used to create pDbFd */
+  sqlite3_file *pDbFd;       /* File handle for the database file */
+  sqlite3_file *pWalFd;      /* File handle for WAL file */
+  u32 iCallback;             /* Value to pass to log callback (or 0) */
+  i64 mxWalSize;             /* Truncate WAL to this size upon reset */
+  int nWiData;               /* Size of array apWiData */
+  int szFirstBlock;          /* Size of first block written to WAL file */
+  volatile u32 **apWiData;   /* Pointer to wal-index content in memory */
+  u32 szPage;                /* Database page size */
+  i16 readLock;              /* Which read lock is being held.  -1 for none */
+  u8 syncFlags;              /* Flags to use to sync header writes */
+  u8 exclusiveMode;          /* Non-zero if connection is in exclusive mode */
+  u8 writeLock;              /* True if in a write transaction */
+  u8 ckptLock;               /* True if holding a checkpoint lock */
+  u8 readOnly;               /* WAL_RDWR, WAL_RDONLY, or WAL_SHM_RDONLY */
+  u8 truncateOnCommit;       /* True to truncate WAL file on commit */
+  u8 syncHeader;             /* Fsync the WAL header if true */
+  u8 padToSectorBoundary;    /* Pad transactions out to the next sector */
+  WalIndexHdr hdr;           /* Wal-index header for current transaction */
+  u32 minFrame;              /* Ignore wal frames before this one */
+  u32 iReCksum;              /* On commit, recalculate checksums from here */
+  const char *zWalName;      /* Name of WAL file */
+  u32 nCkpt;                 /* Checkpoint sequence counter in the wal-header */
+#ifdef SQLITE_DEBUG
+  u8 lockError;              /* True if a locking error has occurred */
+#endif
+#ifdef SQLITE_ENABLE_SNAPSHOT
+  WalIndexHdr *pSnapshot;    /* Start transaction here if not NULL */
+#endif
+};
+
+/*
+** Candidate values for Wal.exclusiveMode.
+*/
+#define WAL_NORMAL_MODE     0
+#define WAL_EXCLUSIVE_MODE  1     
+#define WAL_HEAPMEMORY_MODE 2
+
+/*
+** Possible values for WAL.readOnly
+*/
+#define WAL_RDWR        0    /* Normal read/write connection */
+#define WAL_RDONLY      1    /* The WAL file is readonly */
+#define WAL_SHM_RDONLY  2    /* The SHM file is readonly */
+
+/*
+** Each page of the wal-index mapping contains a hash-table made up of
+** an array of HASHTABLE_NSLOT elements of the following type.
+*/
+typedef u16 ht_slot;
+
+/*
+** This structure is used to implement an iterator that loops through
+** all frames in the WAL in database page order. Where two or more frames
+** correspond to the same database page, the iterator visits only the 
+** frame most recently written to the WAL (in other words, the frame with
+** the largest index).
+**
+** The internals of this structure are only accessed by:
+**
+**   walIteratorInit() - Create a new iterator,
+**   walIteratorNext() - Step an iterator,
+**   walIteratorFree() - Free an iterator.
+**
+** This functionality is used by the checkpoint code (see walCheckpoint()).
+*/
+struct WalIterator {
+  int iPrior;                     /* Last result returned from the iterator */
+  int nSegment;                   /* Number of entries in aSegment[] */
+  struct WalSegment {
+    int iNext;                    /* Next slot in aIndex[] not yet returned */
+    ht_slot *aIndex;              /* i0, i1, i2... such that aPgno[iN] ascend */
+    u32 *aPgno;                   /* Array of page numbers. */
+    int nEntry;                   /* Nr. of entries in aPgno[] and aIndex[] */
+    int iZero;                    /* Frame number associated with aPgno[0] */
+  } aSegment[1];                  /* One for every 32KB page in the wal-index */
+};
+
+/*
+** Define the parameters of the hash tables in the wal-index file. There
+** is a hash-table following every HASHTABLE_NPAGE page numbers in the
+** wal-index.
+**
+** Changing any of these constants will alter the wal-index format and
+** create incompatibilities.
+*/
+#define HASHTABLE_NPAGE      4096                 /* Must be power of 2 */
+#define HASHTABLE_HASH_1     383                  /* Should be prime */
+#define HASHTABLE_NSLOT      (HASHTABLE_NPAGE*2)  /* Must be a power of 2 */
+
+/* 
+** The block of page numbers associated with the first hash-table in a
+** wal-index is smaller than usual. This is so that there is a complete
+** hash-table on each aligned 32KB page of the wal-index.
+*/
+#define HASHTABLE_NPAGE_ONE  (HASHTABLE_NPAGE - (WALINDEX_HDR_SIZE/sizeof(u32)))
+
+/* The wal-index is divided into pages of WALINDEX_PGSZ bytes each. */
+#define WALINDEX_PGSZ   (                                         \
+    sizeof(ht_slot)*HASHTABLE_NSLOT + HASHTABLE_NPAGE*sizeof(u32) \
+)
+
+/*
+** Obtain a pointer to the iPage'th page of the wal-index. The wal-index
+** is broken into pages of WALINDEX_PGSZ bytes. Wal-index pages are
+** numbered from zero.
+**
+** If this call is successful, *ppPage is set to point to the wal-index
+** page and SQLITE_OK is returned. If an error (an OOM or VFS error) occurs,
+** then an SQLite error code is returned and *ppPage is set to 0.
+*/
+static int walIndexPage(Wal *pWal, int iPage, volatile u32 **ppPage){
+  int rc = SQLITE_OK;
+
+  /* Enlarge the pWal->apWiData[] array if required */
+  if( pWal->nWiData<=iPage ){
+    int nByte = sizeof(u32*)*(iPage+1);
+    volatile u32 **apNew;
+    apNew = (volatile u32 **)sqlite3_realloc64((void *)pWal->apWiData, nByte);
+    if( !apNew ){
+      *ppPage = 0;
+      return SQLITE_NOMEM_BKPT;
+    }
+    memset((void*)&apNew[pWal->nWiData], 0,
+           sizeof(u32*)*(iPage+1-pWal->nWiData));
+    pWal->apWiData = apNew;
+    pWal->nWiData = iPage+1;
+  }
+
+  /* Request a pointer to the required page from the VFS */
+  if( pWal->apWiData[iPage]==0 ){
+    if( pWal->exclusiveMode==WAL_HEAPMEMORY_MODE ){
+      pWal->apWiData[iPage] = (u32 volatile *)sqlite3MallocZero(WALINDEX_PGSZ);
+      if( !pWal->apWiData[iPage] ) rc = SQLITE_NOMEM_BKPT;
+    }else{
+      rc = sqlite3OsShmMap(pWal->pDbFd, iPage, WALINDEX_PGSZ, 
+          pWal->writeLock, (void volatile **)&pWal->apWiData[iPage]
+      );
+      if( rc==SQLITE_READONLY ){
+        pWal->readOnly |= WAL_SHM_RDONLY;
+        rc = SQLITE_OK;
+      }
+    }
+  }
+
+  *ppPage = pWal->apWiData[iPage];
+  assert( iPage==0 || *ppPage || rc!=SQLITE_OK );
+  return rc;
+}
+
+/*
+** Return a pointer to the WalCkptInfo structure in the wal-index.
+*/
+static volatile WalCkptInfo *walCkptInfo(Wal *pWal){
+  assert( pWal->nWiData>0 && pWal->apWiData[0] );
+  return (volatile WalCkptInfo*)&(pWal->apWiData[0][sizeof(WalIndexHdr)/2]);
+}
+
+/*
+** Return a pointer to the WalIndexHdr structure in the wal-index.
+*/
+static volatile WalIndexHdr *walIndexHdr(Wal *pWal){
+  assert( pWal->nWiData>0 && pWal->apWiData[0] );
+  return (volatile WalIndexHdr*)pWal->apWiData[0];
+}
+
+/*
+** The argument to this macro must be of type u32. On a little-endian
+** architecture, it returns the u32 value that results from interpreting
+** the 4 bytes as a big-endian value. On a big-endian architecture, it
+** returns the value that would be produced by interpreting the 4 bytes
+** of the input value as a little-endian integer.
+*/
+#define BYTESWAP32(x) ( \
+    (((x)&0x000000FF)<<24) + (((x)&0x0000FF00)<<8)  \
+  + (((x)&0x00FF0000)>>8)  + (((x)&0xFF000000)>>24) \
+)
+
+/*
+** Generate or extend an 8 byte checksum based on the data in 
+** array aByte[] and the initial values of aIn[0] and aIn[1] (or
+** initial values of 0 and 0 if aIn==NULL).
+**
+** The checksum is written back into aOut[] before returning.
+**
+** nByte must be a positive multiple of 8.
+*/
+static void walChecksumBytes(
+  int nativeCksum, /* True for native byte-order, false for non-native */
+  u8 *a,           /* Content to be checksummed */
+  int nByte,       /* Bytes of content in a[].  Must be a multiple of 8. */
+  const u32 *aIn,  /* Initial checksum value input */
+  u32 *aOut        /* OUT: Final checksum value output */
+){
+  u32 s1, s2;
+  u32 *aData = (u32 *)a;
+  u32 *aEnd = (u32 *)&a[nByte];
+
+  if( aIn ){
+    s1 = aIn[0];
+    s2 = aIn[1];
+  }else{
+    s1 = s2 = 0;
+  }
+
+  assert( nByte>=8 );
+  assert( (nByte&0x00000007)==0 );
+
+  if( nativeCksum ){
+    do {
+      s1 += *aData++ + s2;
+      s2 += *aData++ + s1;
+    }while( aData<aEnd );
+  }else{
+    do {
+      s1 += BYTESWAP32(aData[0]) + s2;
+      s2 += BYTESWAP32(aData[1]) + s1;
+      aData += 2;
+    }while( aData<aEnd );
+  }
+
+  aOut[0] = s1;
+  aOut[1] = s2;
+}
+
+static void walShmBarrier(Wal *pWal){
+  if( pWal->exclusiveMode!=WAL_HEAPMEMORY_MODE ){
+    sqlite3OsShmBarrier(pWal->pDbFd);
+  }
+}
+
+/*
+** Write the header information in pWal->hdr into the wal-index.
+**
+** The checksum on pWal->hdr is updated before it is written.
+*/
+static void walIndexWriteHdr(Wal *pWal){
+  volatile WalIndexHdr *aHdr = walIndexHdr(pWal);
+  const int nCksum = offsetof(WalIndexHdr, aCksum);
+
+  assert( pWal->writeLock );
+  pWal->hdr.isInit = 1;
+  pWal->hdr.iVersion = WALINDEX_MAX_VERSION;
+  walChecksumBytes(1, (u8*)&pWal->hdr, nCksum, 0, pWal->hdr.aCksum);
+  memcpy((void*)&aHdr[1], (const void*)&pWal->hdr, sizeof(WalIndexHdr));
+  walShmBarrier(pWal);
+  memcpy((void*)&aHdr[0], (const void*)&pWal->hdr, sizeof(WalIndexHdr));
+}
+
+/*
+** This function encodes a single frame header and writes it to a buffer
+** supplied by the caller. A frame-header is made up of a series of 
+** 4-byte big-endian integers, as follows:
+**
+**     0: Page number.
+**     4: For commit records, the size of the database image in pages 
+**        after the commit. For all other records, zero.
+**     8: Salt-1 (copied from the wal-header)
+**    12: Salt-2 (copied from the wal-header)
+**    16: Checksum-1.
+**    20: Checksum-2.
+*/
+static void walEncodeFrame(
+  Wal *pWal,                      /* The write-ahead log */
+  u32 iPage,                      /* Database page number for frame */
+  u32 nTruncate,                  /* New db size (or 0 for non-commit frames) */
+  u8 *aData,                      /* Pointer to page data */
+  u8 *aFrame                      /* OUT: Write encoded frame here */
+){
+  int nativeCksum;                /* True for native byte-order checksums */
+  u32 *aCksum = pWal->hdr.aFrameCksum;
+  assert( WAL_FRAME_HDRSIZE==24 );
+  sqlite3Put4byte(&aFrame[0], iPage);
+  sqlite3Put4byte(&aFrame[4], nTruncate);
+  if( pWal->iReCksum==0 ){
+    memcpy(&aFrame[8], pWal->hdr.aSalt, 8);
+
+    nativeCksum = (pWal->hdr.bigEndCksum==SQLITE_BIGENDIAN);
+    walChecksumBytes(nativeCksum, aFrame, 8, aCksum, aCksum);
+    walChecksumBytes(nativeCksum, aData, pWal->szPage, aCksum, aCksum);
+
+    sqlite3Put4byte(&aFrame[16], aCksum[0]);
+    sqlite3Put4byte(&aFrame[20], aCksum[1]);
+  }else{
+    memset(&aFrame[8], 0, 16);
+  }
+}
+
+/*
+** Check to see if the frame with header in aFrame[] and content
+** in aData[] is valid.  If it is a valid frame, fill *piPage and
+** *pnTruncate and return true.  Return if the frame is not valid.
+*/
+static int walDecodeFrame(
+  Wal *pWal,                      /* The write-ahead log */
+  u32 *piPage,                    /* OUT: Database page number for frame */
+  u32 *pnTruncate,                /* OUT: New db size (or 0 if not commit) */
+  u8 *aData,                      /* Pointer to page data (for checksum) */
+  u8 *aFrame                      /* Frame data */
+){
+  int nativeCksum;                /* True for native byte-order checksums */
+  u32 *aCksum = pWal->hdr.aFrameCksum;
+  u32 pgno;                       /* Page number of the frame */
+  assert( WAL_FRAME_HDRSIZE==24 );
+
+  /* A frame is only valid if the salt values in the frame-header
+  ** match the salt values in the wal-header. 
+  */
+  if( memcmp(&pWal->hdr.aSalt, &aFrame[8], 8)!=0 ){
+    return 0;
+  }
+
+  /* A frame is only valid if the page number is creater than zero.
+  */
+  pgno = sqlite3Get4byte(&aFrame[0]);
+  if( pgno==0 ){
+    return 0;
+  }
+
+  /* A frame is only valid if a checksum of the WAL header,
+  ** all prior frams, the first 16 bytes of this frame-header, 
+  ** and the frame-data matches the checksum in the last 8 
+  ** bytes of this frame-header.
+  */
+  nativeCksum = (pWal->hdr.bigEndCksum==SQLITE_BIGENDIAN);
+  walChecksumBytes(nativeCksum, aFrame, 8, aCksum, aCksum);
+  walChecksumBytes(nativeCksum, aData, pWal->szPage, aCksum, aCksum);
+  if( aCksum[0]!=sqlite3Get4byte(&aFrame[16]) 
+   || aCksum[1]!=sqlite3Get4byte(&aFrame[20]) 
+  ){
+    /* Checksum failed. */
+    return 0;
+  }
+
+  /* If we reach this point, the frame is valid.  Return the page number
+  ** and the new database size.
+  */
+  *piPage = pgno;
+  *pnTruncate = sqlite3Get4byte(&aFrame[4]);
+  return 1;
+}
+
+
+#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
+/*
+** Names of locks.  This routine is used to provide debugging output and is not
+** a part of an ordinary build.
+*/
+static const char *walLockName(int lockIdx){
+  if( lockIdx==WAL_WRITE_LOCK ){
+    return "WRITE-LOCK";
+  }else if( lockIdx==WAL_CKPT_LOCK ){
+    return "CKPT-LOCK";
+  }else if( lockIdx==WAL_RECOVER_LOCK ){
+    return "RECOVER-LOCK";
+  }else{
+    static char zName[15];
+    sqlite3_snprintf(sizeof(zName), zName, "READ-LOCK[%d]",
+                     lockIdx-WAL_READ_LOCK(0));
+    return zName;
+  }
+}
+#endif /*defined(SQLITE_TEST) || defined(SQLITE_DEBUG) */
+    
+
+/*
+** Set or release locks on the WAL.  Locks are either shared or exclusive.
+** A lock cannot be moved directly between shared and exclusive - it must go
+** through the unlocked state first.
+**
+** In locking_mode=EXCLUSIVE, all of these routines become no-ops.
+*/
+static int walLockShared(Wal *pWal, int lockIdx){
+  int rc;
+  if( pWal->exclusiveMode ) return SQLITE_OK;
+  rc = sqlite3OsShmLock(pWal->pDbFd, lockIdx, 1,
+                        SQLITE_SHM_LOCK | SQLITE_SHM_SHARED);
+  WALTRACE(("WAL%p: acquire SHARED-%s %s\n", pWal,
+            walLockName(lockIdx), rc ? "failed" : "ok"));
+  VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && rc!=SQLITE_BUSY); )
+  return rc;
+}
+static void walUnlockShared(Wal *pWal, int lockIdx){
+  if( pWal->exclusiveMode ) return;
+  (void)sqlite3OsShmLock(pWal->pDbFd, lockIdx, 1,
+                         SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED);
+  WALTRACE(("WAL%p: release SHARED-%s\n", pWal, walLockName(lockIdx)));
+}
+static int walLockExclusive(Wal *pWal, int lockIdx, int n){
+  int rc;
+  if( pWal->exclusiveMode ) return SQLITE_OK;
+  rc = sqlite3OsShmLock(pWal->pDbFd, lockIdx, n,
+                        SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE);
+  WALTRACE(("WAL%p: acquire EXCLUSIVE-%s cnt=%d %s\n", pWal,
+            walLockName(lockIdx), n, rc ? "failed" : "ok"));
+  VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && rc!=SQLITE_BUSY); )
+  return rc;
+}
+static void walUnlockExclusive(Wal *pWal, int lockIdx, int n){
+  if( pWal->exclusiveMode ) return;
+  (void)sqlite3OsShmLock(pWal->pDbFd, lockIdx, n,
+                         SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE);
+  WALTRACE(("WAL%p: release EXCLUSIVE-%s cnt=%d\n", pWal,
+             walLockName(lockIdx), n));
+}
+
+/*
+** Compute a hash on a page number.  The resulting hash value must land
+** between 0 and (HASHTABLE_NSLOT-1).  The walHashNext() function advances
+** the hash to the next value in the event of a collision.
+*/
+static int walHash(u32 iPage){
+  assert( iPage>0 );
+  assert( (HASHTABLE_NSLOT & (HASHTABLE_NSLOT-1))==0 );
+  return (iPage*HASHTABLE_HASH_1) & (HASHTABLE_NSLOT-1);
+}
+static int walNextHash(int iPriorHash){
+  return (iPriorHash+1)&(HASHTABLE_NSLOT-1);
+}
+
+/* 
+** Return pointers to the hash table and page number array stored on
+** page iHash of the wal-index. The wal-index is broken into 32KB pages
+** numbered starting from 0.
+**
+** Set output variable *paHash to point to the start of the hash table
+** in the wal-index file. Set *piZero to one less than the frame 
+** number of the first frame indexed by this hash table. If a
+** slot in the hash table is set to N, it refers to frame number 
+** (*piZero+N) in the log.
+**
+** Finally, set *paPgno so that *paPgno[1] is the page number of the
+** first frame indexed by the hash table, frame (*piZero+1).
+*/
+static int walHashGet(
+  Wal *pWal,                      /* WAL handle */
+  int iHash,                      /* Find the iHash'th table */
+  volatile ht_slot **paHash,      /* OUT: Pointer to hash index */
+  volatile u32 **paPgno,          /* OUT: Pointer to page number array */
+  u32 *piZero                     /* OUT: Frame associated with *paPgno[0] */
+){
+  int rc;                         /* Return code */
+  volatile u32 *aPgno;
+
+  rc = walIndexPage(pWal, iHash, &aPgno);
+  assert( rc==SQLITE_OK || iHash>0 );
+
+  if( rc==SQLITE_OK ){
+    u32 iZero;
+    volatile ht_slot *aHash;
+
+    aHash = (volatile ht_slot *)&aPgno[HASHTABLE_NPAGE];
+    if( iHash==0 ){
+      aPgno = &aPgno[WALINDEX_HDR_SIZE/sizeof(u32)];
+      iZero = 0;
+    }else{
+      iZero = HASHTABLE_NPAGE_ONE + (iHash-1)*HASHTABLE_NPAGE;
+    }
+  
+    *paPgno = &aPgno[-1];
+    *paHash = aHash;
+    *piZero = iZero;
+  }
+  return rc;
+}
+
+/*
+** Return the number of the wal-index page that contains the hash-table
+** and page-number array that contain entries corresponding to WAL frame
+** iFrame. The wal-index is broken up into 32KB pages. Wal-index pages 
+** are numbered starting from 0.
+*/
+static int walFramePage(u32 iFrame){
+  int iHash = (iFrame+HASHTABLE_NPAGE-HASHTABLE_NPAGE_ONE-1) / HASHTABLE_NPAGE;
+  assert( (iHash==0 || iFrame>HASHTABLE_NPAGE_ONE)
+       && (iHash>=1 || iFrame<=HASHTABLE_NPAGE_ONE)
+       && (iHash<=1 || iFrame>(HASHTABLE_NPAGE_ONE+HASHTABLE_NPAGE))
+       && (iHash>=2 || iFrame<=HASHTABLE_NPAGE_ONE+HASHTABLE_NPAGE)
+       && (iHash<=2 || iFrame>(HASHTABLE_NPAGE_ONE+2*HASHTABLE_NPAGE))
+  );
+  return iHash;
+}
+
+/*
+** Return the page number associated with frame iFrame in this WAL.
+*/
+static u32 walFramePgno(Wal *pWal, u32 iFrame){
+  int iHash = walFramePage(iFrame);
+  if( iHash==0 ){
+    return pWal->apWiData[0][WALINDEX_HDR_SIZE/sizeof(u32) + iFrame - 1];
+  }
+  return pWal->apWiData[iHash][(iFrame-1-HASHTABLE_NPAGE_ONE)%HASHTABLE_NPAGE];
+}
+
+/*
+** Remove entries from the hash table that point to WAL slots greater
+** than pWal->hdr.mxFrame.
+**
+** This function is called whenever pWal->hdr.mxFrame is decreased due
+** to a rollback or savepoint.
+**
+** At most only the hash table containing pWal->hdr.mxFrame needs to be
+** updated.  Any later hash tables will be automatically cleared when
+** pWal->hdr.mxFrame advances to the point where those hash tables are
+** actually needed.
+*/
+static void walCleanupHash(Wal *pWal){
+  volatile ht_slot *aHash = 0;    /* Pointer to hash table to clear */
+  volatile u32 *aPgno = 0;        /* Page number array for hash table */
+  u32 iZero = 0;                  /* frame == (aHash[x]+iZero) */
+  int iLimit = 0;                 /* Zero values greater than this */
+  int nByte;                      /* Number of bytes to zero in aPgno[] */
+  int i;                          /* Used to iterate through aHash[] */
+
+  assert( pWal->writeLock );
+  testcase( pWal->hdr.mxFrame==HASHTABLE_NPAGE_ONE-1 );
+  testcase( pWal->hdr.mxFrame==HASHTABLE_NPAGE_ONE );
+  testcase( pWal->hdr.mxFrame==HASHTABLE_NPAGE_ONE+1 );
+
+  if( pWal->hdr.mxFrame==0 ) return;
+
+  /* Obtain pointers to the hash-table and page-number array containing 
+  ** the entry that corresponds to frame pWal->hdr.mxFrame. It is guaranteed
+  ** that the page said hash-table and array reside on is already mapped.
+  */
+  assert( pWal->nWiData>walFramePage(pWal->hdr.mxFrame) );
+  assert( pWal->apWiData[walFramePage(pWal->hdr.mxFrame)] );
+  walHashGet(pWal, walFramePage(pWal->hdr.mxFrame), &aHash, &aPgno, &iZero);
+
+  /* Zero all hash-table entries that correspond to frame numbers greater
+  ** than pWal->hdr.mxFrame.
+  */
+  iLimit = pWal->hdr.mxFrame - iZero;
+  assert( iLimit>0 );
+  for(i=0; i<HASHTABLE_NSLOT; i++){
+    if( aHash[i]>iLimit ){
+      aHash[i] = 0;
+    }
+  }
+  
+  /* Zero the entries in the aPgno array that correspond to frames with
+  ** frame numbers greater than pWal->hdr.mxFrame. 
+  */
+  nByte = (int)((char *)aHash - (char *)&aPgno[iLimit+1]);
+  memset((void *)&aPgno[iLimit+1], 0, nByte);
+
+#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
+  /* Verify that the every entry in the mapping region is still reachable
+  ** via the hash table even after the cleanup.
+  */
+  if( iLimit ){
+    int j;           /* Loop counter */
+    int iKey;        /* Hash key */
+    for(j=1; j<=iLimit; j++){
+      for(iKey=walHash(aPgno[j]); aHash[iKey]; iKey=walNextHash(iKey)){
+        if( aHash[iKey]==j ) break;
+      }
+      assert( aHash[iKey]==j );
+    }
+  }
+#endif /* SQLITE_ENABLE_EXPENSIVE_ASSERT */
+}
+
+
+/*
+** Set an entry in the wal-index that will map database page number
+** pPage into WAL frame iFrame.
+*/
+static int walIndexAppend(Wal *pWal, u32 iFrame, u32 iPage){
+  int rc;                         /* Return code */
+  u32 iZero = 0;                  /* One less than frame number of aPgno[1] */
+  volatile u32 *aPgno = 0;        /* Page number array */
+  volatile ht_slot *aHash = 0;    /* Hash table */
+
+  rc = walHashGet(pWal, walFramePage(iFrame), &aHash, &aPgno, &iZero);
+
+  /* Assuming the wal-index file was successfully mapped, populate the
+  ** page number array and hash table entry.
+  */
+  if( rc==SQLITE_OK ){
+    int iKey;                     /* Hash table key */
+    int idx;                      /* Value to write to hash-table slot */
+    int nCollide;                 /* Number of hash collisions */
+
+    idx = iFrame - iZero;
+    assert( idx <= HASHTABLE_NSLOT/2 + 1 );
+    
+    /* If this is the first entry to be added to this hash-table, zero the
+    ** entire hash table and aPgno[] array before proceeding. 
+    */
+    if( idx==1 ){
+      int nByte = (int)((u8 *)&aHash[HASHTABLE_NSLOT] - (u8 *)&aPgno[1]);
+      memset((void*)&aPgno[1], 0, nByte);
+    }
+
+    /* If the entry in aPgno[] is already set, then the previous writer
+    ** must have exited unexpectedly in the middle of a transaction (after
+    ** writing one or more dirty pages to the WAL to free up memory). 
+    ** Remove the remnants of that writers uncommitted transaction from 
+    ** the hash-table before writing any new entries.
+    */
+    if( aPgno[idx] ){
+      walCleanupHash(pWal);
+      assert( !aPgno[idx] );
+    }
+
+    /* Write the aPgno[] array entry and the hash-table slot. */
+    nCollide = idx;
+    for(iKey=walHash(iPage); aHash[iKey]; iKey=walNextHash(iKey)){
+      if( (nCollide--)==0 ) return SQLITE_CORRUPT_BKPT;
+    }
+    aPgno[idx] = iPage;
+    aHash[iKey] = (ht_slot)idx;
+
+#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
+    /* Verify that the number of entries in the hash table exactly equals
+    ** the number of entries in the mapping region.
+    */
+    {
+      int i;           /* Loop counter */
+      int nEntry = 0;  /* Number of entries in the hash table */
+      for(i=0; i<HASHTABLE_NSLOT; i++){ if( aHash[i] ) nEntry++; }
+      assert( nEntry==idx );
+    }
+
+    /* Verify that the every entry in the mapping region is reachable
+    ** via the hash table.  This turns out to be a really, really expensive
+    ** thing to check, so only do this occasionally - not on every
+    ** iteration.
+    */
+    if( (idx&0x3ff)==0 ){
+      int i;           /* Loop counter */
+      for(i=1; i<=idx; i++){
+        for(iKey=walHash(aPgno[i]); aHash[iKey]; iKey=walNextHash(iKey)){
+          if( aHash[iKey]==i ) break;
+        }
+        assert( aHash[iKey]==i );
+      }
+    }
+#endif /* SQLITE_ENABLE_EXPENSIVE_ASSERT */
+  }
+
+
+  return rc;
+}
+
+
+/*
+** Recover the wal-index by reading the write-ahead log file. 
+**
+** This routine first tries to establish an exclusive lock on the
+** wal-index to prevent other threads/processes from doing anything
+** with the WAL or wal-index while recovery is running.  The
+** WAL_RECOVER_LOCK is also held so that other threads will know
+** that this thread is running recovery.  If unable to establish
+** the necessary locks, this routine returns SQLITE_BUSY.
+*/
+static int walIndexRecover(Wal *pWal){
+  int rc;                         /* Return Code */
+  i64 nSize;                      /* Size of log file */
+  u32 aFrameCksum[2] = {0, 0};
+  int iLock;                      /* Lock offset to lock for checkpoint */
+  int nLock;                      /* Number of locks to hold */
+
+  /* Obtain an exclusive lock on all byte in the locking range not already
+  ** locked by the caller. The caller is guaranteed to have locked the
+  ** WAL_WRITE_LOCK byte, and may have also locked the WAL_CKPT_LOCK byte.
+  ** If successful, the same bytes that are locked here are unlocked before
+  ** this function returns.
+  */
+  assert( pWal->ckptLock==1 || pWal->ckptLock==0 );
+  assert( WAL_ALL_BUT_WRITE==WAL_WRITE_LOCK+1 );
+  assert( WAL_CKPT_LOCK==WAL_ALL_BUT_WRITE );
+  assert( pWal->writeLock );
+  iLock = WAL_ALL_BUT_WRITE + pWal->ckptLock;
+  nLock = SQLITE_SHM_NLOCK - iLock;
+  rc = walLockExclusive(pWal, iLock, nLock);
+  if( rc ){
+    return rc;
+  }
+  WALTRACE(("WAL%p: recovery begin...\n", pWal));
+
+  memset(&pWal->hdr, 0, sizeof(WalIndexHdr));
+
+  rc = sqlite3OsFileSize(pWal->pWalFd, &nSize);
+  if( rc!=SQLITE_OK ){
+    goto recovery_error;
+  }
+
+  if( nSize>WAL_HDRSIZE ){
+    u8 aBuf[WAL_HDRSIZE];         /* Buffer to load WAL header into */
+    u8 *aFrame = 0;               /* Malloc'd buffer to load entire frame */
+    int szFrame;                  /* Number of bytes in buffer aFrame[] */
+    u8 *aData;                    /* Pointer to data part of aFrame buffer */
+    int iFrame;                   /* Index of last frame read */
+    i64 iOffset;                  /* Next offset to read from log file */
+    int szPage;                   /* Page size according to the log */
+    u32 magic;                    /* Magic value read from WAL header */
+    u32 version;                  /* Magic value read from WAL header */
+    int isValid;                  /* True if this frame is valid */
+
+    /* Read in the WAL header. */
+    rc = sqlite3OsRead(pWal->pWalFd, aBuf, WAL_HDRSIZE, 0);
+    if( rc!=SQLITE_OK ){
+      goto recovery_error;
+    }
+
+    /* If the database page size is not a power of two, or is greater than
+    ** SQLITE_MAX_PAGE_SIZE, conclude that the WAL file contains no valid 
+    ** data. Similarly, if the 'magic' value is invalid, ignore the whole
+    ** WAL file.
+    */
+    magic = sqlite3Get4byte(&aBuf[0]);
+    szPage = sqlite3Get4byte(&aBuf[8]);
+    if( (magic&0xFFFFFFFE)!=WAL_MAGIC 
+     || szPage&(szPage-1) 
+     || szPage>SQLITE_MAX_PAGE_SIZE 
+     || szPage<512 
+    ){
+      goto finished;
+    }
+    pWal->hdr.bigEndCksum = (u8)(magic&0x00000001);
+    pWal->szPage = szPage;
+    pWal->nCkpt = sqlite3Get4byte(&aBuf[12]);
+    memcpy(&pWal->hdr.aSalt, &aBuf[16], 8);
+
+    /* Verify that the WAL header checksum is correct */
+    walChecksumBytes(pWal->hdr.bigEndCksum==SQLITE_BIGENDIAN, 
+        aBuf, WAL_HDRSIZE-2*4, 0, pWal->hdr.aFrameCksum
+    );
+    if( pWal->hdr.aFrameCksum[0]!=sqlite3Get4byte(&aBuf[24])
+     || pWal->hdr.aFrameCksum[1]!=sqlite3Get4byte(&aBuf[28])
+    ){
+      goto finished;
+    }
+
+    /* Verify that the version number on the WAL format is one that
+    ** are able to understand */
+    version = sqlite3Get4byte(&aBuf[4]);
+    if( version!=WAL_MAX_VERSION ){
+      rc = SQLITE_CANTOPEN_BKPT;
+      goto finished;
+    }
+
+    /* Malloc a buffer to read frames into. */
+    szFrame = szPage + WAL_FRAME_HDRSIZE;
+    aFrame = (u8 *)sqlite3_malloc64(szFrame);
+    if( !aFrame ){
+      rc = SQLITE_NOMEM_BKPT;
+      goto recovery_error;
+    }
+    aData = &aFrame[WAL_FRAME_HDRSIZE];
+
+    /* Read all frames from the log file. */
+    iFrame = 0;
+    for(iOffset=WAL_HDRSIZE; (iOffset+szFrame)<=nSize; iOffset+=szFrame){
+      u32 pgno;                   /* Database page number for frame */
+      u32 nTruncate;              /* dbsize field from frame header */
+
+      /* Read and decode the next log frame. */
+      iFrame++;
+      rc = sqlite3OsRead(pWal->pWalFd, aFrame, szFrame, iOffset);
+      if( rc!=SQLITE_OK ) break;
+      isValid = walDecodeFrame(pWal, &pgno, &nTruncate, aData, aFrame);
+      if( !isValid ) break;
+      rc = walIndexAppend(pWal, iFrame, pgno);
+      if( rc!=SQLITE_OK ) break;
+
+      /* If nTruncate is non-zero, this is a commit record. */
+      if( nTruncate ){
+        pWal->hdr.mxFrame = iFrame;
+        pWal->hdr.nPage = nTruncate;
+        pWal->hdr.szPage = (u16)((szPage&0xff00) | (szPage>>16));
+        testcase( szPage<=32768 );
+        testcase( szPage>=65536 );
+        aFrameCksum[0] = pWal->hdr.aFrameCksum[0];
+        aFrameCksum[1] = pWal->hdr.aFrameCksum[1];
+      }
+    }
+
+    sqlite3_free(aFrame);
+  }
+
+finished:
+  if( rc==SQLITE_OK ){
+    volatile WalCkptInfo *pInfo;
+    int i;
+    pWal->hdr.aFrameCksum[0] = aFrameCksum[0];
+    pWal->hdr.aFrameCksum[1] = aFrameCksum[1];
+    walIndexWriteHdr(pWal);
+
+    /* Reset the checkpoint-header. This is safe because this thread is 
+    ** currently holding locks that exclude all other readers, writers and
+    ** checkpointers.
+    */
+    pInfo = walCkptInfo(pWal);
+    pInfo->nBackfill = 0;
+    pInfo->nBackfillAttempted = pWal->hdr.mxFrame;
+    pInfo->aReadMark[0] = 0;
+    for(i=1; i<WAL_NREADER; i++) pInfo->aReadMark[i] = READMARK_NOT_USED;
+    if( pWal->hdr.mxFrame ) pInfo->aReadMark[1] = pWal->hdr.mxFrame;
+
+    /* If more than one frame was recovered from the log file, report an
+    ** event via sqlite3_log(). This is to help with identifying performance
+    ** problems caused by applications routinely shutting down without
+    ** checkpointing the log file.
+    */
+    if( pWal->hdr.nPage ){
+      sqlite3_log(SQLITE_NOTICE_RECOVER_WAL,
+          "recovered %d frames from WAL file %s",
+          pWal->hdr.mxFrame, pWal->zWalName
+      );
+    }
+  }
+
+recovery_error:
+  WALTRACE(("WAL%p: recovery %s\n", pWal, rc ? "failed" : "ok"));
+  walUnlockExclusive(pWal, iLock, nLock);
+  return rc;
+}
+
+/*
+** Close an open wal-index.
+*/
+static void walIndexClose(Wal *pWal, int isDelete){
+  if( pWal->exclusiveMode==WAL_HEAPMEMORY_MODE ){
+    int i;
+    for(i=0; i<pWal->nWiData; i++){
+      sqlite3_free((void *)pWal->apWiData[i]);
+      pWal->apWiData[i] = 0;
+    }
+  }else{
+    sqlite3OsShmUnmap(pWal->pDbFd, isDelete);
+  }
+}
+
+/* 
+** Open a connection to the WAL file zWalName. The database file must 
+** already be opened on connection pDbFd. The buffer that zWalName points
+** to must remain valid for the lifetime of the returned Wal* handle.
+**
+** A SHARED lock should be held on the database file when this function
+** is called. The purpose of this SHARED lock is to prevent any other
+** client from unlinking the WAL or wal-index file. If another process
+** were to do this just after this client opened one of these files, the
+** system would be badly broken.
+**
+** If the log file is successfully opened, SQLITE_OK is returned and 
+** *ppWal is set to point to a new WAL handle. If an error occurs,
+** an SQLite error code is returned and *ppWal is left unmodified.
+*/
+SQLITE_PRIVATE int sqlite3WalOpen(
+  sqlite3_vfs *pVfs,              /* vfs module to open wal and wal-index */
+  sqlite3_file *pDbFd,            /* The open database file */
+  const char *zWalName,           /* Name of the WAL file */
+  int bNoShm,                     /* True to run in heap-memory mode */
+  i64 mxWalSize,                  /* Truncate WAL to this size on reset */
+  Wal **ppWal                     /* OUT: Allocated Wal handle */
+){
+  int rc;                         /* Return Code */
+  Wal *pRet;                      /* Object to allocate and return */
+  int flags;                      /* Flags passed to OsOpen() */
+
+  assert( zWalName && zWalName[0] );
+  assert( pDbFd );
+
+  /* In the amalgamation, the os_unix.c and os_win.c source files come before
+  ** this source file.  Verify that the #defines of the locking byte offsets
+  ** in os_unix.c and os_win.c agree with the WALINDEX_LOCK_OFFSET value.
+  ** For that matter, if the lock offset ever changes from its initial design
+  ** value of 120, we need to know that so there is an assert() to check it.
+  */
+  assert( 120==WALINDEX_LOCK_OFFSET );
+  assert( 136==WALINDEX_HDR_SIZE );
+#ifdef WIN_SHM_BASE
+  assert( WIN_SHM_BASE==WALINDEX_LOCK_OFFSET );
+#endif
+#ifdef UNIX_SHM_BASE
+  assert( UNIX_SHM_BASE==WALINDEX_LOCK_OFFSET );
+#endif
+
+
+  /* Allocate an instance of struct Wal to return. */
+  *ppWal = 0;
+  pRet = (Wal*)sqlite3MallocZero(sizeof(Wal) + pVfs->szOsFile);
+  if( !pRet ){
+    return SQLITE_NOMEM_BKPT;
+  }
+
+  pRet->pVfs = pVfs;
+  pRet->pWalFd = (sqlite3_file *)&pRet[1];
+  pRet->pDbFd = pDbFd;
+  pRet->readLock = -1;
+  pRet->mxWalSize = mxWalSize;
+  pRet->zWalName = zWalName;
+  pRet->syncHeader = 1;
+  pRet->padToSectorBoundary = 1;
+  pRet->exclusiveMode = (bNoShm ? WAL_HEAPMEMORY_MODE: WAL_NORMAL_MODE);
+
+  /* Open file handle on the write-ahead log file. */
+  flags = (SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|SQLITE_OPEN_WAL);
+  rc = sqlite3OsOpen(pVfs, zWalName, pRet->pWalFd, flags, &flags);
+  if( rc==SQLITE_OK && flags&SQLITE_OPEN_READONLY ){
+    pRet->readOnly = WAL_RDONLY;
+  }
+
+  if( rc!=SQLITE_OK ){
+    walIndexClose(pRet, 0);
+    sqlite3OsClose(pRet->pWalFd);
+    sqlite3_free(pRet);
+  }else{
+    int iDC = sqlite3OsDeviceCharacteristics(pDbFd);
+    if( iDC & SQLITE_IOCAP_SEQUENTIAL ){ pRet->syncHeader = 0; }
+    if( iDC & SQLITE_IOCAP_POWERSAFE_OVERWRITE ){
+      pRet->padToSectorBoundary = 0;
+    }
+    *ppWal = pRet;
+    WALTRACE(("WAL%d: opened\n", pRet));
+  }
+  return rc;
+}
+
+/*
+** Change the size to which the WAL file is trucated on each reset.
+*/
+SQLITE_PRIVATE void sqlite3WalLimit(Wal *pWal, i64 iLimit){
+  if( pWal ) pWal->mxWalSize = iLimit;
+}
+
+/*
+** Find the smallest page number out of all pages held in the WAL that
+** has not been returned by any prior invocation of this method on the
+** same WalIterator object.   Write into *piFrame the frame index where
+** that page was last written into the WAL.  Write into *piPage the page
+** number.
+**
+** Return 0 on success.  If there are no pages in the WAL with a page
+** number larger than *piPage, then return 1.
+*/
+static int walIteratorNext(
+  WalIterator *p,               /* Iterator */
+  u32 *piPage,                  /* OUT: The page number of the next page */
+  u32 *piFrame                  /* OUT: Wal frame index of next page */
+){
+  u32 iMin;                     /* Result pgno must be greater than iMin */
+  u32 iRet = 0xFFFFFFFF;        /* 0xffffffff is never a valid page number */
+  int i;                        /* For looping through segments */
+
+  iMin = p->iPrior;
+  assert( iMin<0xffffffff );
+  for(i=p->nSegment-1; i>=0; i--){
+    struct WalSegment *pSegment = &p->aSegment[i];
+    while( pSegment->iNext<pSegment->nEntry ){
+      u32 iPg = pSegment->aPgno[pSegment->aIndex[pSegment->iNext]];
+      if( iPg>iMin ){
+        if( iPg<iRet ){
+          iRet = iPg;
+          *piFrame = pSegment->iZero + pSegment->aIndex[pSegment->iNext];
+        }
+        break;
+      }
+      pSegment->iNext++;
+    }
+  }
+
+  *piPage = p->iPrior = iRet;
+  return (iRet==0xFFFFFFFF);
+}
+
+/*
+** This function merges two sorted lists into a single sorted list.
+**
+** aLeft[] and aRight[] are arrays of indices.  The sort key is
+** aContent[aLeft[]] and aContent[aRight[]].  Upon entry, the following
+** is guaranteed for all J<K:
+**
+**        aContent[aLeft[J]] < aContent[aLeft[K]]
+**        aContent[aRight[J]] < aContent[aRight[K]]
+**
+** This routine overwrites aRight[] with a new (probably longer) sequence
+** of indices such that the aRight[] contains every index that appears in
+** either aLeft[] or the old aRight[] and such that the second condition
+** above is still met.
+**
+** The aContent[aLeft[X]] values will be unique for all X.  And the
+** aContent[aRight[X]] values will be unique too.  But there might be
+** one or more combinations of X and Y such that
+**
+**      aLeft[X]!=aRight[Y]  &&  aContent[aLeft[X]] == aContent[aRight[Y]]
+**
+** When that happens, omit the aLeft[X] and use the aRight[Y] index.
+*/
+static void walMerge(
+  const u32 *aContent,            /* Pages in wal - keys for the sort */
+  ht_slot *aLeft,                 /* IN: Left hand input list */
+  int nLeft,                      /* IN: Elements in array *paLeft */
+  ht_slot **paRight,              /* IN/OUT: Right hand input list */
+  int *pnRight,                   /* IN/OUT: Elements in *paRight */
+  ht_slot *aTmp                   /* Temporary buffer */
+){
+  int iLeft = 0;                  /* Current index in aLeft */
+  int iRight = 0;                 /* Current index in aRight */
+  int iOut = 0;                   /* Current index in output buffer */
+  int nRight = *pnRight;
+  ht_slot *aRight = *paRight;
+
+  assert( nLeft>0 && nRight>0 );
+  while( iRight<nRight || iLeft<nLeft ){
+    ht_slot logpage;
+    Pgno dbpage;
+
+    if( (iLeft<nLeft) 
+     && (iRight>=nRight || aContent[aLeft[iLeft]]<aContent[aRight[iRight]])
+    ){
+      logpage = aLeft[iLeft++];
+    }else{
+      logpage = aRight[iRight++];
+    }
+    dbpage = aContent[logpage];
+
+    aTmp[iOut++] = logpage;
+    if( iLeft<nLeft && aContent[aLeft[iLeft]]==dbpage ) iLeft++;
+
+    assert( iLeft>=nLeft || aContent[aLeft[iLeft]]>dbpage );
+    assert( iRight>=nRight || aContent[aRight[iRight]]>dbpage );
+  }
+
+  *paRight = aLeft;
+  *pnRight = iOut;
+  memcpy(aLeft, aTmp, sizeof(aTmp[0])*iOut);
+}
+
+/*
+** Sort the elements in list aList using aContent[] as the sort key.
+** Remove elements with duplicate keys, preferring to keep the
+** larger aList[] values.
+**
+** The aList[] entries are indices into aContent[].  The values in
+** aList[] are to be sorted so that for all J<K:
+**
+**      aContent[aList[J]] < aContent[aList[K]]
+**
+** For any X and Y such that
+**
+**      aContent[aList[X]] == aContent[aList[Y]]
+**
+** Keep the larger of the two values aList[X] and aList[Y] and discard
+** the smaller.
+*/
+static void walMergesort(
+  const u32 *aContent,            /* Pages in wal */
+  ht_slot *aBuffer,               /* Buffer of at least *pnList items to use */
+  ht_slot *aList,                 /* IN/OUT: List to sort */
+  int *pnList                     /* IN/OUT: Number of elements in aList[] */
+){
+  struct Sublist {
+    int nList;                    /* Number of elements in aList */
+    ht_slot *aList;               /* Pointer to sub-list content */
+  };
+
+  const int nList = *pnList;      /* Size of input list */
+  int nMerge = 0;                 /* Number of elements in list aMerge */
+  ht_slot *aMerge = 0;            /* List to be merged */
+  int iList;                      /* Index into input list */
+  u32 iSub = 0;                   /* Index into aSub array */
+  struct Sublist aSub[13];        /* Array of sub-lists */
+
+  memset(aSub, 0, sizeof(aSub));
+  assert( nList<=HASHTABLE_NPAGE && nList>0 );
+  assert( HASHTABLE_NPAGE==(1<<(ArraySize(aSub)-1)) );
+
+  for(iList=0; iList<nList; iList++){
+    nMerge = 1;
+    aMerge = &aList[iList];
+    for(iSub=0; iList & (1<<iSub); iSub++){
+      struct Sublist *p;
+      assert( iSub<ArraySize(aSub) );
+      p = &aSub[iSub];
+      assert( p->aList && p->nList<=(1<<iSub) );
+      assert( p->aList==&aList[iList&~((2<<iSub)-1)] );
+      walMerge(aContent, p->aList, p->nList, &aMerge, &nMerge, aBuffer);
+    }
+    aSub[iSub].aList = aMerge;
+    aSub[iSub].nList = nMerge;
+  }
+
+  for(iSub++; iSub<ArraySize(aSub); iSub++){
+    if( nList & (1<<iSub) ){
+      struct Sublist *p;
+      assert( iSub<ArraySize(aSub) );
+      p = &aSub[iSub];
+      assert( p->nList<=(1<<iSub) );
+      assert( p->aList==&aList[nList&~((2<<iSub)-1)] );
+      walMerge(aContent, p->aList, p->nList, &aMerge, &nMerge, aBuffer);
+    }
+  }
+  assert( aMerge==aList );
+  *pnList = nMerge;
+
+#ifdef SQLITE_DEBUG
+  {
+    int i;
+    for(i=1; i<*pnList; i++){
+      assert( aContent[aList[i]] > aContent[aList[i-1]] );
+    }
+  }
+#endif
+}
+
+/* 
+** Free an iterator allocated by walIteratorInit().
+*/
+static void walIteratorFree(WalIterator *p){
+  sqlite3_free(p);
+}
+
+/*
+** Construct a WalInterator object that can be used to loop over all 
+** pages in the WAL in ascending order. The caller must hold the checkpoint
+** lock.
+**
+** On success, make *pp point to the newly allocated WalInterator object
+** return SQLITE_OK. Otherwise, return an error code. If this routine
+** returns an error, the value of *pp is undefined.
+**
+** The calling routine should invoke walIteratorFree() to destroy the
+** WalIterator object when it has finished with it.
+*/
+static int walIteratorInit(Wal *pWal, WalIterator **pp){
+  WalIterator *p;                 /* Return value */
+  int nSegment;                   /* Number of segments to merge */
+  u32 iLast;                      /* Last frame in log */
+  int nByte;                      /* Number of bytes to allocate */
+  int i;                          /* Iterator variable */
+  ht_slot *aTmp;                  /* Temp space used by merge-sort */
+  int rc = SQLITE_OK;             /* Return Code */
+
+  /* This routine only runs while holding the checkpoint lock. And
+  ** it only runs if there is actually content in the log (mxFrame>0).
+  */
+  assert( pWal->ckptLock && pWal->hdr.mxFrame>0 );
+  iLast = pWal->hdr.mxFrame;
+
+  /* Allocate space for the WalIterator object. */
+  nSegment = walFramePage(iLast) + 1;
+  nByte = sizeof(WalIterator) 
+        + (nSegment-1)*sizeof(struct WalSegment)
+        + iLast*sizeof(ht_slot);
+  p = (WalIterator *)sqlite3_malloc64(nByte);
+  if( !p ){
+    return SQLITE_NOMEM_BKPT;
+  }
+  memset(p, 0, nByte);
+  p->nSegment = nSegment;
+
+  /* Allocate temporary space used by the merge-sort routine. This block
+  ** of memory will be freed before this function returns.
+  */
+  aTmp = (ht_slot *)sqlite3_malloc64(
+      sizeof(ht_slot) * (iLast>HASHTABLE_NPAGE?HASHTABLE_NPAGE:iLast)
+  );
+  if( !aTmp ){
+    rc = SQLITE_NOMEM_BKPT;
+  }
+
+  for(i=0; rc==SQLITE_OK && i<nSegment; i++){
+    volatile ht_slot *aHash;
+    u32 iZero;
+    volatile u32 *aPgno;
+
+    rc = walHashGet(pWal, i, &aHash, &aPgno, &iZero);
+    if( rc==SQLITE_OK ){
+      int j;                      /* Counter variable */
+      int nEntry;                 /* Number of entries in this segment */
+      ht_slot *aIndex;            /* Sorted index for this segment */
+
+      aPgno++;
+      if( (i+1)==nSegment ){
+        nEntry = (int)(iLast - iZero);
+      }else{
+        nEntry = (int)((u32*)aHash - (u32*)aPgno);
+      }
+      aIndex = &((ht_slot *)&p->aSegment[p->nSegment])[iZero];
+      iZero++;
+  
+      for(j=0; j<nEntry; j++){
+        aIndex[j] = (ht_slot)j;
+      }
+      walMergesort((u32 *)aPgno, aTmp, aIndex, &nEntry);
+      p->aSegment[i].iZero = iZero;
+      p->aSegment[i].nEntry = nEntry;
+      p->aSegment[i].aIndex = aIndex;
+      p->aSegment[i].aPgno = (u32 *)aPgno;
+    }
+  }
+  sqlite3_free(aTmp);
+
+  if( rc!=SQLITE_OK ){
+    walIteratorFree(p);
+  }
+  *pp = p;
+  return rc;
+}
+
+/*
+** Attempt to obtain the exclusive WAL lock defined by parameters lockIdx and
+** n. If the attempt fails and parameter xBusy is not NULL, then it is a
+** busy-handler function. Invoke it and retry the lock until either the
+** lock is successfully obtained or the busy-handler returns 0.
+*/
+static int walBusyLock(
+  Wal *pWal,                      /* WAL connection */
+  int (*xBusy)(void*),            /* Function to call when busy */
+  void *pBusyArg,                 /* Context argument for xBusyHandler */
+  int lockIdx,                    /* Offset of first byte to lock */
+  int n                           /* Number of bytes to lock */
+){
+  int rc;
+  do {
+    rc = walLockExclusive(pWal, lockIdx, n);
+  }while( xBusy && rc==SQLITE_BUSY && xBusy(pBusyArg) );
+  return rc;
+}
+
+/*
+** The cache of the wal-index header must be valid to call this function.
+** Return the page-size in bytes used by the database.
+*/
+static int walPagesize(Wal *pWal){
+  return (pWal->hdr.szPage&0xfe00) + ((pWal->hdr.szPage&0x0001)<<16);
+}
+
+/*
+** The following is guaranteed when this function is called:
+**
+**   a) the WRITER lock is held,
+**   b) the entire log file has been checkpointed, and
+**   c) any existing readers are reading exclusively from the database
+**      file - there are no readers that may attempt to read a frame from
+**      the log file.
+**
+** This function updates the shared-memory structures so that the next
+** client to write to the database (which may be this one) does so by
+** writing frames into the start of the log file.
+**
+** The value of parameter salt1 is used as the aSalt[1] value in the 
+** new wal-index header. It should be passed a pseudo-random value (i.e. 
+** one obtained from sqlite3_randomness()).
+*/
+static void walRestartHdr(Wal *pWal, u32 salt1){
+  volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
+  int i;                          /* Loop counter */
+  u32 *aSalt = pWal->hdr.aSalt;   /* Big-endian salt values */
+  pWal->nCkpt++;
+  pWal->hdr.mxFrame = 0;
+  sqlite3Put4byte((u8*)&aSalt[0], 1 + sqlite3Get4byte((u8*)&aSalt[0]));
+  memcpy(&pWal->hdr.aSalt[1], &salt1, 4);
+  walIndexWriteHdr(pWal);
+  pInfo->nBackfill = 0;
+  pInfo->nBackfillAttempted = 0;
+  pInfo->aReadMark[1] = 0;
+  for(i=2; i<WAL_NREADER; i++) pInfo->aReadMark[i] = READMARK_NOT_USED;
+  assert( pInfo->aReadMark[0]==0 );
+}
+
+/*
+** Copy as much content as we can from the WAL back into the database file
+** in response to an sqlite3_wal_checkpoint() request or the equivalent.
+**
+** The amount of information copies from WAL to database might be limited
+** by active readers.  This routine will never overwrite a database page
+** that a concurrent reader might be using.
+**
+** All I/O barrier operations (a.k.a fsyncs) occur in this routine when
+** SQLite is in WAL-mode in synchronous=NORMAL.  That means that if 
+** checkpoints are always run by a background thread or background 
+** process, foreground threads will never block on a lengthy fsync call.
+**
+** Fsync is called on the WAL before writing content out of the WAL and
+** into the database.  This ensures that if the new content is persistent
+** in the WAL and can be recovered following a power-loss or hard reset.
+**
+** Fsync is also called on the database file if (and only if) the entire
+** WAL content is copied into the database file.  This second fsync makes
+** it safe to delete the WAL since the new content will persist in the
+** database file.
+**
+** This routine uses and updates the nBackfill field of the wal-index header.
+** This is the only routine that will increase the value of nBackfill.  
+** (A WAL reset or recovery will revert nBackfill to zero, but not increase
+** its value.)
+**
+** The caller must be holding sufficient locks to ensure that no other
+** checkpoint is running (in any other thread or process) at the same
+** time.
+*/
+static int walCheckpoint(
+  Wal *pWal,                      /* Wal connection */
+  int eMode,                      /* One of PASSIVE, FULL or RESTART */
+  int (*xBusy)(void*),            /* Function to call when busy */
+  void *pBusyArg,                 /* Context argument for xBusyHandler */
+  int sync_flags,                 /* Flags for OsSync() (or 0) */
+  u8 *zBuf                        /* Temporary buffer to use */
+){
+  int rc = SQLITE_OK;             /* Return code */
+  int szPage;                     /* Database page-size */
+  WalIterator *pIter = 0;         /* Wal iterator context */
+  u32 iDbpage = 0;                /* Next database page to write */
+  u32 iFrame = 0;                 /* Wal frame containing data for iDbpage */
+  u32 mxSafeFrame;                /* Max frame that can be backfilled */
+  u32 mxPage;                     /* Max database page to write */
+  int i;                          /* Loop counter */
+  volatile WalCkptInfo *pInfo;    /* The checkpoint status information */
+
+  szPage = walPagesize(pWal);
+  testcase( szPage<=32768 );
+  testcase( szPage>=65536 );
+  pInfo = walCkptInfo(pWal);
+  if( pInfo->nBackfill<pWal->hdr.mxFrame ){
+
+    /* Allocate the iterator */
+    rc = walIteratorInit(pWal, &pIter);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    assert( pIter );
+
+    /* EVIDENCE-OF: R-62920-47450 The busy-handler callback is never invoked
+    ** in the SQLITE_CHECKPOINT_PASSIVE mode. */
+    assert( eMode!=SQLITE_CHECKPOINT_PASSIVE || xBusy==0 );
+
+    /* Compute in mxSafeFrame the index of the last frame of the WAL that is
+    ** safe to write into the database.  Frames beyond mxSafeFrame might
+    ** overwrite database pages that are in use by active readers and thus
+    ** cannot be backfilled from the WAL.
+    */
+    mxSafeFrame = pWal->hdr.mxFrame;
+    mxPage = pWal->hdr.nPage;
+    for(i=1; i<WAL_NREADER; i++){
+      /* Thread-sanitizer reports that the following is an unsafe read,
+      ** as some other thread may be in the process of updating the value
+      ** of the aReadMark[] slot. The assumption here is that if that is
+      ** happening, the other client may only be increasing the value,
+      ** not decreasing it. So assuming either that either the "old" or
+      ** "new" version of the value is read, and not some arbitrary value
+      ** that would never be written by a real client, things are still 
+      ** safe.  */
+      u32 y = pInfo->aReadMark[i];
+      if( mxSafeFrame>y ){
+        assert( y<=pWal->hdr.mxFrame );
+        rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(i), 1);
+        if( rc==SQLITE_OK ){
+          pInfo->aReadMark[i] = (i==1 ? mxSafeFrame : READMARK_NOT_USED);
+          walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
+        }else if( rc==SQLITE_BUSY ){
+          mxSafeFrame = y;
+          xBusy = 0;
+        }else{
+          goto walcheckpoint_out;
+        }
+      }
+    }
+
+    if( pInfo->nBackfill<mxSafeFrame
+     && (rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(0),1))==SQLITE_OK
+    ){
+      i64 nSize;                    /* Current size of database file */
+      u32 nBackfill = pInfo->nBackfill;
+
+      pInfo->nBackfillAttempted = mxSafeFrame;
+
+      /* Sync the WAL to disk */
+      if( sync_flags ){
+        rc = sqlite3OsSync(pWal->pWalFd, sync_flags);
+      }
+
+      /* If the database may grow as a result of this checkpoint, hint
+      ** about the eventual size of the db file to the VFS layer.
+      */
+      if( rc==SQLITE_OK ){
+        i64 nReq = ((i64)mxPage * szPage);
+        rc = sqlite3OsFileSize(pWal->pDbFd, &nSize);
+        if( rc==SQLITE_OK && nSize<nReq ){
+          sqlite3OsFileControlHint(pWal->pDbFd, SQLITE_FCNTL_SIZE_HINT, &nReq);
+        }
+      }
+
+
+      /* Iterate through the contents of the WAL, copying data to the db file */
+      while( rc==SQLITE_OK && 0==walIteratorNext(pIter, &iDbpage, &iFrame) ){
+        i64 iOffset;
+        assert( walFramePgno(pWal, iFrame)==iDbpage );
+        if( iFrame<=nBackfill || iFrame>mxSafeFrame || iDbpage>mxPage ){
+          continue;
+        }
+        iOffset = walFrameOffset(iFrame, szPage) + WAL_FRAME_HDRSIZE;
+        /* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL file */
+        rc = sqlite3OsRead(pWal->pWalFd, zBuf, szPage, iOffset);
+        if( rc!=SQLITE_OK ) break;
+        iOffset = (iDbpage-1)*(i64)szPage;
+        testcase( IS_BIG_INT(iOffset) );
+        rc = sqlite3OsWrite(pWal->pDbFd, zBuf, szPage, iOffset);
+        if( rc!=SQLITE_OK ) break;
+      }
+
+      /* If work was actually accomplished... */
+      if( rc==SQLITE_OK ){
+        if( mxSafeFrame==walIndexHdr(pWal)->mxFrame ){
+          i64 szDb = pWal->hdr.nPage*(i64)szPage;
+          testcase( IS_BIG_INT(szDb) );
+          rc = sqlite3OsTruncate(pWal->pDbFd, szDb);
+          if( rc==SQLITE_OK && sync_flags ){
+            rc = sqlite3OsSync(pWal->pDbFd, sync_flags);
+          }
+        }
+        if( rc==SQLITE_OK ){
+          pInfo->nBackfill = mxSafeFrame;
+        }
+      }
+
+      /* Release the reader lock held while backfilling */
+      walUnlockExclusive(pWal, WAL_READ_LOCK(0), 1);
+    }
+
+    if( rc==SQLITE_BUSY ){
+      /* Reset the return code so as not to report a checkpoint failure
+      ** just because there are active readers.  */
+      rc = SQLITE_OK;
+    }
+  }
+
+  /* If this is an SQLITE_CHECKPOINT_RESTART or TRUNCATE operation, and the
+  ** entire wal file has been copied into the database file, then block 
+  ** until all readers have finished using the wal file. This ensures that 
+  ** the next process to write to the database restarts the wal file.
+  */
+  if( rc==SQLITE_OK && eMode!=SQLITE_CHECKPOINT_PASSIVE ){
+    assert( pWal->writeLock );
+    if( pInfo->nBackfill<pWal->hdr.mxFrame ){
+      rc = SQLITE_BUSY;
+    }else if( eMode>=SQLITE_CHECKPOINT_RESTART ){
+      u32 salt1;
+      sqlite3_randomness(4, &salt1);
+      assert( pInfo->nBackfill==pWal->hdr.mxFrame );
+      rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(1), WAL_NREADER-1);
+      if( rc==SQLITE_OK ){
+        if( eMode==SQLITE_CHECKPOINT_TRUNCATE ){
+          /* IMPLEMENTATION-OF: R-44699-57140 This mode works the same way as
+          ** SQLITE_CHECKPOINT_RESTART with the addition that it also
+          ** truncates the log file to zero bytes just prior to a
+          ** successful return.
+          **
+          ** In theory, it might be safe to do this without updating the
+          ** wal-index header in shared memory, as all subsequent reader or
+          ** writer clients should see that the entire log file has been
+          ** checkpointed and behave accordingly. This seems unsafe though,
+          ** as it would leave the system in a state where the contents of
+          ** the wal-index header do not match the contents of the 
+          ** file-system. To avoid this, update the wal-index header to
+          ** indicate that the log file contains zero valid frames.  */
+          walRestartHdr(pWal, salt1);
+          rc = sqlite3OsTruncate(pWal->pWalFd, 0);
+        }
+        walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
+      }
+    }
+  }
+
+ walcheckpoint_out:
+  walIteratorFree(pIter);
+  return rc;
+}
+
+/*
+** If the WAL file is currently larger than nMax bytes in size, truncate
+** it to exactly nMax bytes. If an error occurs while doing so, ignore it.
+*/
+static void walLimitSize(Wal *pWal, i64 nMax){
+  i64 sz;
+  int rx;
+  sqlite3BeginBenignMalloc();
+  rx = sqlite3OsFileSize(pWal->pWalFd, &sz);
+  if( rx==SQLITE_OK && (sz > nMax ) ){
+    rx = sqlite3OsTruncate(pWal->pWalFd, nMax);
+  }
+  sqlite3EndBenignMalloc();
+  if( rx ){
+    sqlite3_log(rx, "cannot limit WAL size: %s", pWal->zWalName);
+  }
+}
+
+/*
+** Close a connection to a log file.
+*/
+SQLITE_PRIVATE int sqlite3WalClose(
+  Wal *pWal,                      /* Wal to close */
+  int sync_flags,                 /* Flags to pass to OsSync() (or 0) */
+  int nBuf,
+  u8 *zBuf                        /* Buffer of at least nBuf bytes */
+){
+  int rc = SQLITE_OK;
+  if( pWal ){
+    int isDelete = 0;             /* True to unlink wal and wal-index files */
+
+    /* If an EXCLUSIVE lock can be obtained on the database file (using the
+    ** ordinary, rollback-mode locking methods, this guarantees that the
+    ** connection associated with this log file is the only connection to
+    ** the database. In this case checkpoint the database and unlink both
+    ** the wal and wal-index files.
+    **
+    ** The EXCLUSIVE lock is not released before returning.
+    */
+    rc = sqlite3OsLock(pWal->pDbFd, SQLITE_LOCK_EXCLUSIVE);
+    if( rc==SQLITE_OK ){
+      if( pWal->exclusiveMode==WAL_NORMAL_MODE ){
+        pWal->exclusiveMode = WAL_EXCLUSIVE_MODE;
+      }
+      rc = sqlite3WalCheckpoint(
+          pWal, SQLITE_CHECKPOINT_PASSIVE, 0, 0, sync_flags, nBuf, zBuf, 0, 0
+      );
+      if( rc==SQLITE_OK ){
+        int bPersist = -1;
+        sqlite3OsFileControlHint(
+            pWal->pDbFd, SQLITE_FCNTL_PERSIST_WAL, &bPersist
+        );
+        if( bPersist!=1 ){
+          /* Try to delete the WAL file if the checkpoint completed and
+          ** fsyned (rc==SQLITE_OK) and if we are not in persistent-wal
+          ** mode (!bPersist) */
+          isDelete = 1;
+        }else if( pWal->mxWalSize>=0 ){
+          /* Try to truncate the WAL file to zero bytes if the checkpoint
+          ** completed and fsynced (rc==SQLITE_OK) and we are in persistent
+          ** WAL mode (bPersist) and if the PRAGMA journal_size_limit is a
+          ** non-negative value (pWal->mxWalSize>=0).  Note that we truncate
+          ** to zero bytes as truncating to the journal_size_limit might
+          ** leave a corrupt WAL file on disk. */
+          walLimitSize(pWal, 0);
+        }
+      }
+    }
+
+    walIndexClose(pWal, isDelete);
+    sqlite3OsClose(pWal->pWalFd);
+    if( isDelete ){
+      sqlite3BeginBenignMalloc();
+      sqlite3OsDelete(pWal->pVfs, pWal->zWalName, 0);
+      sqlite3EndBenignMalloc();
+    }
+    WALTRACE(("WAL%p: closed\n", pWal));
+    sqlite3_free((void *)pWal->apWiData);
+    sqlite3_free(pWal);
+  }
+  return rc;
+}
+
+/*
+** Try to read the wal-index header.  Return 0 on success and 1 if
+** there is a problem.
+**
+** The wal-index is in shared memory.  Another thread or process might
+** be writing the header at the same time this procedure is trying to
+** read it, which might result in inconsistency.  A dirty read is detected
+** by verifying that both copies of the header are the same and also by
+** a checksum on the header.
+**
+** If and only if the read is consistent and the header is different from
+** pWal->hdr, then pWal->hdr is updated to the content of the new header
+** and *pChanged is set to 1.
+**
+** If the checksum cannot be verified return non-zero. If the header
+** is read successfully and the checksum verified, return zero.
+*/
+static int walIndexTryHdr(Wal *pWal, int *pChanged){
+  u32 aCksum[2];                  /* Checksum on the header content */
+  WalIndexHdr h1, h2;             /* Two copies of the header content */
+  WalIndexHdr volatile *aHdr;     /* Header in shared memory */
+
+  /* The first page of the wal-index must be mapped at this point. */
+  assert( pWal->nWiData>0 && pWal->apWiData[0] );
+
+  /* Read the header. This might happen concurrently with a write to the
+  ** same area of shared memory on a different CPU in a SMP,
+  ** meaning it is possible that an inconsistent snapshot is read
+  ** from the file. If this happens, return non-zero.
+  **
+  ** There are two copies of the header at the beginning of the wal-index.
+  ** When reading, read [0] first then [1].  Writes are in the reverse order.
+  ** Memory barriers are used to prevent the compiler or the hardware from
+  ** reordering the reads and writes.
+  */
+  aHdr = walIndexHdr(pWal);
+  memcpy(&h1, (void *)&aHdr[0], sizeof(h1));
+  walShmBarrier(pWal);
+  memcpy(&h2, (void *)&aHdr[1], sizeof(h2));
+
+  if( memcmp(&h1, &h2, sizeof(h1))!=0 ){
+    return 1;   /* Dirty read */
+  }  
+  if( h1.isInit==0 ){
+    return 1;   /* Malformed header - probably all zeros */
+  }
+  walChecksumBytes(1, (u8*)&h1, sizeof(h1)-sizeof(h1.aCksum), 0, aCksum);
+  if( aCksum[0]!=h1.aCksum[0] || aCksum[1]!=h1.aCksum[1] ){
+    return 1;   /* Checksum does not match */
+  }
+
+  if( memcmp(&pWal->hdr, &h1, sizeof(WalIndexHdr)) ){
+    *pChanged = 1;
+    memcpy(&pWal->hdr, &h1, sizeof(WalIndexHdr));
+    pWal->szPage = (pWal->hdr.szPage&0xfe00) + ((pWal->hdr.szPage&0x0001)<<16);
+    testcase( pWal->szPage<=32768 );
+    testcase( pWal->szPage>=65536 );
+  }
+
+  /* The header was successfully read. Return zero. */
+  return 0;
+}
+
+/*
+** Read the wal-index header from the wal-index and into pWal->hdr.
+** If the wal-header appears to be corrupt, try to reconstruct the
+** wal-index from the WAL before returning.
+**
+** Set *pChanged to 1 if the wal-index header value in pWal->hdr is
+** changed by this operation.  If pWal->hdr is unchanged, set *pChanged
+** to 0.
+**
+** If the wal-index header is successfully read, return SQLITE_OK. 
+** Otherwise an SQLite error code.
+*/
+static int walIndexReadHdr(Wal *pWal, int *pChanged){
+  int rc;                         /* Return code */
+  int badHdr;                     /* True if a header read failed */
+  volatile u32 *page0;            /* Chunk of wal-index containing header */
+
+  /* Ensure that page 0 of the wal-index (the page that contains the 
+  ** wal-index header) is mapped. Return early if an error occurs here.
+  */
+  assert( pChanged );
+  rc = walIndexPage(pWal, 0, &page0);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  };
+  assert( page0 || pWal->writeLock==0 );
+
+  /* If the first page of the wal-index has been mapped, try to read the
+  ** wal-index header immediately, without holding any lock. This usually
+  ** works, but may fail if the wal-index header is corrupt or currently 
+  ** being modified by another thread or process.
+  */
+  badHdr = (page0 ? walIndexTryHdr(pWal, pChanged) : 1);
+
+  /* If the first attempt failed, it might have been due to a race
+  ** with a writer.  So get a WRITE lock and try again.
+  */
+  assert( badHdr==0 || pWal->writeLock==0 );
+  if( badHdr ){
+    if( pWal->readOnly & WAL_SHM_RDONLY ){
+      if( SQLITE_OK==(rc = walLockShared(pWal, WAL_WRITE_LOCK)) ){
+        walUnlockShared(pWal, WAL_WRITE_LOCK);
+        rc = SQLITE_READONLY_RECOVERY;
+      }
+    }else if( SQLITE_OK==(rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1)) ){
+      pWal->writeLock = 1;
+      if( SQLITE_OK==(rc = walIndexPage(pWal, 0, &page0)) ){
+        badHdr = walIndexTryHdr(pWal, pChanged);
+        if( badHdr ){
+          /* If the wal-index header is still malformed even while holding
+          ** a WRITE lock, it can only mean that the header is corrupted and
+          ** needs to be reconstructed.  So run recovery to do exactly that.
+          */
+          rc = walIndexRecover(pWal);
+          *pChanged = 1;
+        }
+      }
+      pWal->writeLock = 0;
+      walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
+    }
+  }
+
+  /* If the header is read successfully, check the version number to make
+  ** sure the wal-index was not constructed with some future format that
+  ** this version of SQLite cannot understand.
+  */
+  if( badHdr==0 && pWal->hdr.iVersion!=WALINDEX_MAX_VERSION ){
+    rc = SQLITE_CANTOPEN_BKPT;
+  }
+
+  return rc;
+}
+
+/*
+** This is the value that walTryBeginRead returns when it needs to
+** be retried.
+*/
+#define WAL_RETRY  (-1)
+
+/*
+** Attempt to start a read transaction.  This might fail due to a race or
+** other transient condition.  When that happens, it returns WAL_RETRY to
+** indicate to the caller that it is safe to retry immediately.
+**
+** On success return SQLITE_OK.  On a permanent failure (such an
+** I/O error or an SQLITE_BUSY because another process is running
+** recovery) return a positive error code.
+**
+** The useWal parameter is true to force the use of the WAL and disable
+** the case where the WAL is bypassed because it has been completely
+** checkpointed.  If useWal==0 then this routine calls walIndexReadHdr() 
+** to make a copy of the wal-index header into pWal->hdr.  If the 
+** wal-index header has changed, *pChanged is set to 1 (as an indication 
+** to the caller that the local paget cache is obsolete and needs to be 
+** flushed.)  When useWal==1, the wal-index header is assumed to already
+** be loaded and the pChanged parameter is unused.
+**
+** The caller must set the cnt parameter to the number of prior calls to
+** this routine during the current read attempt that returned WAL_RETRY.
+** This routine will start taking more aggressive measures to clear the
+** race conditions after multiple WAL_RETRY returns, and after an excessive
+** number of errors will ultimately return SQLITE_PROTOCOL.  The
+** SQLITE_PROTOCOL return indicates that some other process has gone rogue
+** and is not honoring the locking protocol.  There is a vanishingly small
+** chance that SQLITE_PROTOCOL could be returned because of a run of really
+** bad luck when there is lots of contention for the wal-index, but that
+** possibility is so small that it can be safely neglected, we believe.
+**
+** On success, this routine obtains a read lock on 
+** WAL_READ_LOCK(pWal->readLock).  The pWal->readLock integer is
+** in the range 0 <= pWal->readLock < WAL_NREADER.  If pWal->readLock==(-1)
+** that means the Wal does not hold any read lock.  The reader must not
+** access any database page that is modified by a WAL frame up to and
+** including frame number aReadMark[pWal->readLock].  The reader will
+** use WAL frames up to and including pWal->hdr.mxFrame if pWal->readLock>0
+** Or if pWal->readLock==0, then the reader will ignore the WAL
+** completely and get all content directly from the database file.
+** If the useWal parameter is 1 then the WAL will never be ignored and
+** this routine will always set pWal->readLock>0 on success.
+** When the read transaction is completed, the caller must release the
+** lock on WAL_READ_LOCK(pWal->readLock) and set pWal->readLock to -1.
+**
+** This routine uses the nBackfill and aReadMark[] fields of the header
+** to select a particular WAL_READ_LOCK() that strives to let the
+** checkpoint process do as much work as possible.  This routine might
+** update values of the aReadMark[] array in the header, but if it does
+** so it takes care to hold an exclusive lock on the corresponding
+** WAL_READ_LOCK() while changing values.
+*/
+static int walTryBeginRead(Wal *pWal, int *pChanged, int useWal, int cnt){
+  volatile WalCkptInfo *pInfo;    /* Checkpoint information in wal-index */
+  u32 mxReadMark;                 /* Largest aReadMark[] value */
+  int mxI;                        /* Index of largest aReadMark[] value */
+  int i;                          /* Loop counter */
+  int rc = SQLITE_OK;             /* Return code  */
+  u32 mxFrame;                    /* Wal frame to lock to */
+
+  assert( pWal->readLock<0 );     /* Not currently locked */
+
+  /* Take steps to avoid spinning forever if there is a protocol error.
+  **
+  ** Circumstances that cause a RETRY should only last for the briefest
+  ** instances of time.  No I/O or other system calls are done while the
+  ** locks are held, so the locks should not be held for very long. But 
+  ** if we are unlucky, another process that is holding a lock might get
+  ** paged out or take a page-fault that is time-consuming to resolve, 
+  ** during the few nanoseconds that it is holding the lock.  In that case,
+  ** it might take longer than normal for the lock to free.
+  **
+  ** After 5 RETRYs, we begin calling sqlite3OsSleep().  The first few
+  ** calls to sqlite3OsSleep() have a delay of 1 microsecond.  Really this
+  ** is more of a scheduler yield than an actual delay.  But on the 10th
+  ** an subsequent retries, the delays start becoming longer and longer, 
+  ** so that on the 100th (and last) RETRY we delay for 323 milliseconds.
+  ** The total delay time before giving up is less than 10 seconds.
+  */
+  if( cnt>5 ){
+    int nDelay = 1;                      /* Pause time in microseconds */
+    if( cnt>100 ){
+      VVA_ONLY( pWal->lockError = 1; )
+      return SQLITE_PROTOCOL;
+    }
+    if( cnt>=10 ) nDelay = (cnt-9)*(cnt-9)*39;
+    sqlite3OsSleep(pWal->pVfs, nDelay);
+  }
+
+  if( !useWal ){
+    rc = walIndexReadHdr(pWal, pChanged);
+    if( rc==SQLITE_BUSY ){
+      /* If there is not a recovery running in another thread or process
+      ** then convert BUSY errors to WAL_RETRY.  If recovery is known to
+      ** be running, convert BUSY to BUSY_RECOVERY.  There is a race here
+      ** which might cause WAL_RETRY to be returned even if BUSY_RECOVERY
+      ** would be technically correct.  But the race is benign since with
+      ** WAL_RETRY this routine will be called again and will probably be
+      ** right on the second iteration.
+      */
+      if( pWal->apWiData[0]==0 ){
+        /* This branch is taken when the xShmMap() method returns SQLITE_BUSY.
+        ** We assume this is a transient condition, so return WAL_RETRY. The
+        ** xShmMap() implementation used by the default unix and win32 VFS 
+        ** modules may return SQLITE_BUSY due to a race condition in the 
+        ** code that determines whether or not the shared-memory region 
+        ** must be zeroed before the requested page is returned.
+        */
+        rc = WAL_RETRY;
+      }else if( SQLITE_OK==(rc = walLockShared(pWal, WAL_RECOVER_LOCK)) ){
+        walUnlockShared(pWal, WAL_RECOVER_LOCK);
+        rc = WAL_RETRY;
+      }else if( rc==SQLITE_BUSY ){
+        rc = SQLITE_BUSY_RECOVERY;
+      }
+    }
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+  }
+
+  pInfo = walCkptInfo(pWal);
+  if( !useWal && pInfo->nBackfill==pWal->hdr.mxFrame 
+#ifdef SQLITE_ENABLE_SNAPSHOT
+   && (pWal->pSnapshot==0 || pWal->hdr.mxFrame==0
+     || 0==memcmp(&pWal->hdr, pWal->pSnapshot, sizeof(WalIndexHdr)))
+#endif
+  ){
+    /* The WAL has been completely backfilled (or it is empty).
+    ** and can be safely ignored.
+    */
+    rc = walLockShared(pWal, WAL_READ_LOCK(0));
+    walShmBarrier(pWal);
+    if( rc==SQLITE_OK ){
+      if( memcmp((void *)walIndexHdr(pWal), &pWal->hdr, sizeof(WalIndexHdr)) ){
+        /* It is not safe to allow the reader to continue here if frames
+        ** may have been appended to the log before READ_LOCK(0) was obtained.
+        ** When holding READ_LOCK(0), the reader ignores the entire log file,
+        ** which implies that the database file contains a trustworthy
+        ** snapshot. Since holding READ_LOCK(0) prevents a checkpoint from
+        ** happening, this is usually correct.
+        **
+        ** However, if frames have been appended to the log (or if the log 
+        ** is wrapped and written for that matter) before the READ_LOCK(0)
+        ** is obtained, that is not necessarily true. A checkpointer may
+        ** have started to backfill the appended frames but crashed before
+        ** it finished. Leaving a corrupt image in the database file.
+        */
+        walUnlockShared(pWal, WAL_READ_LOCK(0));
+        return WAL_RETRY;
+      }
+      pWal->readLock = 0;
+      return SQLITE_OK;
+    }else if( rc!=SQLITE_BUSY ){
+      return rc;
+    }
+  }
+
+  /* If we get this far, it means that the reader will want to use
+  ** the WAL to get at content from recent commits.  The job now is
+  ** to select one of the aReadMark[] entries that is closest to
+  ** but not exceeding pWal->hdr.mxFrame and lock that entry.
+  */
+  mxReadMark = 0;
+  mxI = 0;
+  mxFrame = pWal->hdr.mxFrame;
+#ifdef SQLITE_ENABLE_SNAPSHOT
+  if( pWal->pSnapshot && pWal->pSnapshot->mxFrame<mxFrame ){
+    mxFrame = pWal->pSnapshot->mxFrame;
+  }
+#endif
+  for(i=1; i<WAL_NREADER; i++){
+    u32 thisMark = pInfo->aReadMark[i];
+    if( mxReadMark<=thisMark && thisMark<=mxFrame ){
+      assert( thisMark!=READMARK_NOT_USED );
+      mxReadMark = thisMark;
+      mxI = i;
+    }
+  }
+  if( (pWal->readOnly & WAL_SHM_RDONLY)==0
+   && (mxReadMark<mxFrame || mxI==0)
+  ){
+    for(i=1; i<WAL_NREADER; i++){
+      rc = walLockExclusive(pWal, WAL_READ_LOCK(i), 1);
+      if( rc==SQLITE_OK ){
+        mxReadMark = pInfo->aReadMark[i] = mxFrame;
+        mxI = i;
+        walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
+        break;
+      }else if( rc!=SQLITE_BUSY ){
+        return rc;
+      }
+    }
+  }
+  if( mxI==0 ){
+    assert( rc==SQLITE_BUSY || (pWal->readOnly & WAL_SHM_RDONLY)!=0 );
+    return rc==SQLITE_BUSY ? WAL_RETRY : SQLITE_READONLY_CANTLOCK;
+  }
+
+  rc = walLockShared(pWal, WAL_READ_LOCK(mxI));
+  if( rc ){
+    return rc==SQLITE_BUSY ? WAL_RETRY : rc;
+  }
+  /* Now that the read-lock has been obtained, check that neither the
+  ** value in the aReadMark[] array or the contents of the wal-index
+  ** header have changed.
+  **
+  ** It is necessary to check that the wal-index header did not change
+  ** between the time it was read and when the shared-lock was obtained
+  ** on WAL_READ_LOCK(mxI) was obtained to account for the possibility
+  ** that the log file may have been wrapped by a writer, or that frames
+  ** that occur later in the log than pWal->hdr.mxFrame may have been
+  ** copied into the database by a checkpointer. If either of these things
+  ** happened, then reading the database with the current value of
+  ** pWal->hdr.mxFrame risks reading a corrupted snapshot. So, retry
+  ** instead.
+  **
+  ** Before checking that the live wal-index header has not changed
+  ** since it was read, set Wal.minFrame to the first frame in the wal
+  ** file that has not yet been checkpointed. This client will not need
+  ** to read any frames earlier than minFrame from the wal file - they
+  ** can be safely read directly from the database file.
+  **
+  ** Because a ShmBarrier() call is made between taking the copy of 
+  ** nBackfill and checking that the wal-header in shared-memory still
+  ** matches the one cached in pWal->hdr, it is guaranteed that the 
+  ** checkpointer that set nBackfill was not working with a wal-index
+  ** header newer than that cached in pWal->hdr. If it were, that could
+  ** cause a problem. The checkpointer could omit to checkpoint
+  ** a version of page X that lies before pWal->minFrame (call that version
+  ** A) on the basis that there is a newer version (version B) of the same
+  ** page later in the wal file. But if version B happens to like past
+  ** frame pWal->hdr.mxFrame - then the client would incorrectly assume
+  ** that it can read version A from the database file. However, since
+  ** we can guarantee that the checkpointer that set nBackfill could not
+  ** see any pages past pWal->hdr.mxFrame, this problem does not come up.
+  */
+  pWal->minFrame = pInfo->nBackfill+1;
+  walShmBarrier(pWal);
+  if( pInfo->aReadMark[mxI]!=mxReadMark
+   || memcmp((void *)walIndexHdr(pWal), &pWal->hdr, sizeof(WalIndexHdr))
+  ){
+    walUnlockShared(pWal, WAL_READ_LOCK(mxI));
+    return WAL_RETRY;
+  }else{
+    assert( mxReadMark<=pWal->hdr.mxFrame );
+    pWal->readLock = (i16)mxI;
+  }
+  return rc;
+}
+
+/*
+** Begin a read transaction on the database.
+**
+** This routine used to be called sqlite3OpenSnapshot() and with good reason:
+** it takes a snapshot of the state of the WAL and wal-index for the current
+** instant in time.  The current thread will continue to use this snapshot.
+** Other threads might append new content to the WAL and wal-index but
+** that extra content is ignored by the current thread.
+**
+** If the database contents have changes since the previous read
+** transaction, then *pChanged is set to 1 before returning.  The
+** Pager layer will use this to know that is cache is stale and
+** needs to be flushed.
+*/
+SQLITE_PRIVATE int sqlite3WalBeginReadTransaction(Wal *pWal, int *pChanged){
+  int rc;                         /* Return code */
+  int cnt = 0;                    /* Number of TryBeginRead attempts */
+
+#ifdef SQLITE_ENABLE_SNAPSHOT
+  int bChanged = 0;
+  WalIndexHdr *pSnapshot = pWal->pSnapshot;
+  if( pSnapshot && memcmp(pSnapshot, &pWal->hdr, sizeof(WalIndexHdr))!=0 ){
+    bChanged = 1;
+  }
+#endif
+
+  do{
+    rc = walTryBeginRead(pWal, pChanged, 0, ++cnt);
+  }while( rc==WAL_RETRY );
+  testcase( (rc&0xff)==SQLITE_BUSY );
+  testcase( (rc&0xff)==SQLITE_IOERR );
+  testcase( rc==SQLITE_PROTOCOL );
+  testcase( rc==SQLITE_OK );
+
+#ifdef SQLITE_ENABLE_SNAPSHOT
+  if( rc==SQLITE_OK ){
+    if( pSnapshot && memcmp(pSnapshot, &pWal->hdr, sizeof(WalIndexHdr))!=0 ){
+      /* At this point the client has a lock on an aReadMark[] slot holding
+      ** a value equal to or smaller than pSnapshot->mxFrame, but pWal->hdr
+      ** is populated with the wal-index header corresponding to the head
+      ** of the wal file. Verify that pSnapshot is still valid before
+      ** continuing.  Reasons why pSnapshot might no longer be valid:
+      **
+      **    (1)  The WAL file has been reset since the snapshot was taken.
+      **         In this case, the salt will have changed.
+      **
+      **    (2)  A checkpoint as been attempted that wrote frames past
+      **         pSnapshot->mxFrame into the database file.  Note that the
+      **         checkpoint need not have completed for this to cause problems.
+      */
+      volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
+
+      assert( pWal->readLock>0 || pWal->hdr.mxFrame==0 );
+      assert( pInfo->aReadMark[pWal->readLock]<=pSnapshot->mxFrame );
+
+      /* It is possible that there is a checkpointer thread running 
+      ** concurrent with this code. If this is the case, it may be that the
+      ** checkpointer has already determined that it will checkpoint 
+      ** snapshot X, where X is later in the wal file than pSnapshot, but 
+      ** has not yet set the pInfo->nBackfillAttempted variable to indicate 
+      ** its intent. To avoid the race condition this leads to, ensure that
+      ** there is no checkpointer process by taking a shared CKPT lock 
+      ** before checking pInfo->nBackfillAttempted.  */
+      rc = walLockShared(pWal, WAL_CKPT_LOCK);
+
+      if( rc==SQLITE_OK ){
+        /* Check that the wal file has not been wrapped. Assuming that it has
+        ** not, also check that no checkpointer has attempted to checkpoint any
+        ** frames beyond pSnapshot->mxFrame. If either of these conditions are
+        ** true, return SQLITE_BUSY_SNAPSHOT. Otherwise, overwrite pWal->hdr
+        ** with *pSnapshot and set *pChanged as appropriate for opening the
+        ** snapshot.  */
+        if( !memcmp(pSnapshot->aSalt, pWal->hdr.aSalt, sizeof(pWal->hdr.aSalt))
+         && pSnapshot->mxFrame>=pInfo->nBackfillAttempted
+        ){
+          assert( pWal->readLock>0 );
+          memcpy(&pWal->hdr, pSnapshot, sizeof(WalIndexHdr));
+          *pChanged = bChanged;
+        }else{
+          rc = SQLITE_BUSY_SNAPSHOT;
+        }
+
+        /* Release the shared CKPT lock obtained above. */
+        walUnlockShared(pWal, WAL_CKPT_LOCK);
+      }
+
+
+      if( rc!=SQLITE_OK ){
+        sqlite3WalEndReadTransaction(pWal);
+      }
+    }
+  }
+#endif
+  return rc;
+}
+
+/*
+** Finish with a read transaction.  All this does is release the
+** read-lock.
+*/
+SQLITE_PRIVATE void sqlite3WalEndReadTransaction(Wal *pWal){
+  sqlite3WalEndWriteTransaction(pWal);
+  if( pWal->readLock>=0 ){
+    walUnlockShared(pWal, WAL_READ_LOCK(pWal->readLock));
+    pWal->readLock = -1;
+  }
+}
+
+/*
+** Search the wal file for page pgno. If found, set *piRead to the frame that
+** contains the page. Otherwise, if pgno is not in the wal file, set *piRead
+** to zero.
+**
+** Return SQLITE_OK if successful, or an error code if an error occurs. If an
+** error does occur, the final value of *piRead is undefined.
+*/
+SQLITE_PRIVATE int sqlite3WalFindFrame(
+  Wal *pWal,                      /* WAL handle */
+  Pgno pgno,                      /* Database page number to read data for */
+  u32 *piRead                     /* OUT: Frame number (or zero) */
+){
+  u32 iRead = 0;                  /* If !=0, WAL frame to return data from */
+  u32 iLast = pWal->hdr.mxFrame;  /* Last page in WAL for this reader */
+  int iHash;                      /* Used to loop through N hash tables */
+  int iMinHash;
+
+  /* This routine is only be called from within a read transaction. */
+  assert( pWal->readLock>=0 || pWal->lockError );
+
+  /* If the "last page" field of the wal-index header snapshot is 0, then
+  ** no data will be read from the wal under any circumstances. Return early
+  ** in this case as an optimization.  Likewise, if pWal->readLock==0, 
+  ** then the WAL is ignored by the reader so return early, as if the 
+  ** WAL were empty.
+  */
+  if( iLast==0 || pWal->readLock==0 ){
+    *piRead = 0;
+    return SQLITE_OK;
+  }
+
+  /* Search the hash table or tables for an entry matching page number
+  ** pgno. Each iteration of the following for() loop searches one
+  ** hash table (each hash table indexes up to HASHTABLE_NPAGE frames).
+  **
+  ** This code might run concurrently to the code in walIndexAppend()
+  ** that adds entries to the wal-index (and possibly to this hash 
+  ** table). This means the value just read from the hash 
+  ** slot (aHash[iKey]) may have been added before or after the 
+  ** current read transaction was opened. Values added after the
+  ** read transaction was opened may have been written incorrectly -
+  ** i.e. these slots may contain garbage data. However, we assume
+  ** that any slots written before the current read transaction was
+  ** opened remain unmodified.
+  **
+  ** For the reasons above, the if(...) condition featured in the inner
+  ** loop of the following block is more stringent that would be required 
+  ** if we had exclusive access to the hash-table:
+  **
+  **   (aPgno[iFrame]==pgno): 
+  **     This condition filters out normal hash-table collisions.
+  **
+  **   (iFrame<=iLast): 
+  **     This condition filters out entries that were added to the hash
+  **     table after the current read-transaction had started.
+  */
+  iMinHash = walFramePage(pWal->minFrame);
+  for(iHash=walFramePage(iLast); iHash>=iMinHash && iRead==0; iHash--){
+    volatile ht_slot *aHash;      /* Pointer to hash table */
+    volatile u32 *aPgno;          /* Pointer to array of page numbers */
+    u32 iZero;                    /* Frame number corresponding to aPgno[0] */
+    int iKey;                     /* Hash slot index */
+    int nCollide;                 /* Number of hash collisions remaining */
+    int rc;                       /* Error code */
+
+    rc = walHashGet(pWal, iHash, &aHash, &aPgno, &iZero);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    nCollide = HASHTABLE_NSLOT;
+    for(iKey=walHash(pgno); aHash[iKey]; iKey=walNextHash(iKey)){
+      u32 iFrame = aHash[iKey] + iZero;
+      if( iFrame<=iLast && iFrame>=pWal->minFrame && aPgno[aHash[iKey]]==pgno ){
+        assert( iFrame>iRead || CORRUPT_DB );
+        iRead = iFrame;
+      }
+      if( (nCollide--)==0 ){
+        return SQLITE_CORRUPT_BKPT;
+      }
+    }
+  }
+
+#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
+  /* If expensive assert() statements are available, do a linear search
+  ** of the wal-index file content. Make sure the results agree with the
+  ** result obtained using the hash indexes above.  */
+  {
+    u32 iRead2 = 0;
+    u32 iTest;
+    assert( pWal->minFrame>0 );
+    for(iTest=iLast; iTest>=pWal->minFrame; iTest--){
+      if( walFramePgno(pWal, iTest)==pgno ){
+        iRead2 = iTest;
+        break;
+      }
+    }
+    assert( iRead==iRead2 );
+  }
+#endif
+
+  *piRead = iRead;
+  return SQLITE_OK;
+}
+
+/*
+** Read the contents of frame iRead from the wal file into buffer pOut
+** (which is nOut bytes in size). Return SQLITE_OK if successful, or an
+** error code otherwise.
+*/
+SQLITE_PRIVATE int sqlite3WalReadFrame(
+  Wal *pWal,                      /* WAL handle */
+  u32 iRead,                      /* Frame to read */
+  int nOut,                       /* Size of buffer pOut in bytes */
+  u8 *pOut                        /* Buffer to write page data to */
+){
+  int sz;
+  i64 iOffset;
+  sz = pWal->hdr.szPage;
+  sz = (sz&0xfe00) + ((sz&0x0001)<<16);
+  testcase( sz<=32768 );
+  testcase( sz>=65536 );
+  iOffset = walFrameOffset(iRead, sz) + WAL_FRAME_HDRSIZE;
+  /* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL */
+  return sqlite3OsRead(pWal->pWalFd, pOut, (nOut>sz ? sz : nOut), iOffset);
+}
+
+/* 
+** Return the size of the database in pages (or zero, if unknown).
+*/
+SQLITE_PRIVATE Pgno sqlite3WalDbsize(Wal *pWal){
+  if( pWal && ALWAYS(pWal->readLock>=0) ){
+    return pWal->hdr.nPage;
+  }
+  return 0;
+}
+
+
+/* 
+** This function starts a write transaction on the WAL.
+**
+** A read transaction must have already been started by a prior call
+** to sqlite3WalBeginReadTransaction().
+**
+** If another thread or process has written into the database since
+** the read transaction was started, then it is not possible for this
+** thread to write as doing so would cause a fork.  So this routine
+** returns SQLITE_BUSY in that case and no write transaction is started.
+**
+** There can only be a single writer active at a time.
+*/
+SQLITE_PRIVATE int sqlite3WalBeginWriteTransaction(Wal *pWal){
+  int rc;
+
+  /* Cannot start a write transaction without first holding a read
+  ** transaction. */
+  assert( pWal->readLock>=0 );
+  assert( pWal->writeLock==0 && pWal->iReCksum==0 );
+
+  if( pWal->readOnly ){
+    return SQLITE_READONLY;
+  }
+
+  /* Only one writer allowed at a time.  Get the write lock.  Return
+  ** SQLITE_BUSY if unable.
+  */
+  rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1);
+  if( rc ){
+    return rc;
+  }
+  pWal->writeLock = 1;
+
+  /* If another connection has written to the database file since the
+  ** time the read transaction on this connection was started, then
+  ** the write is disallowed.
+  */
+  if( memcmp(&pWal->hdr, (void *)walIndexHdr(pWal), sizeof(WalIndexHdr))!=0 ){
+    walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
+    pWal->writeLock = 0;
+    rc = SQLITE_BUSY_SNAPSHOT;
+  }
+
+  return rc;
+}
+
+/*
+** End a write transaction.  The commit has already been done.  This
+** routine merely releases the lock.
+*/
+SQLITE_PRIVATE int sqlite3WalEndWriteTransaction(Wal *pWal){
+  if( pWal->writeLock ){
+    walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
+    pWal->writeLock = 0;
+    pWal->iReCksum = 0;
+    pWal->truncateOnCommit = 0;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** If any data has been written (but not committed) to the log file, this
+** function moves the write-pointer back to the start of the transaction.
+**
+** Additionally, the callback function is invoked for each frame written
+** to the WAL since the start of the transaction. If the callback returns
+** other than SQLITE_OK, it is not invoked again and the error code is
+** returned to the caller.
+**
+** Otherwise, if the callback function does not return an error, this
+** function returns SQLITE_OK.
+*/
+SQLITE_PRIVATE int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), void *pUndoCtx){
+  int rc = SQLITE_OK;
+  if( ALWAYS(pWal->writeLock) ){
+    Pgno iMax = pWal->hdr.mxFrame;
+    Pgno iFrame;
+  
+    /* Restore the clients cache of the wal-index header to the state it
+    ** was in before the client began writing to the database. 
+    */
+    memcpy(&pWal->hdr, (void *)walIndexHdr(pWal), sizeof(WalIndexHdr));
+
+    for(iFrame=pWal->hdr.mxFrame+1; 
+        ALWAYS(rc==SQLITE_OK) && iFrame<=iMax; 
+        iFrame++
+    ){
+      /* This call cannot fail. Unless the page for which the page number
+      ** is passed as the second argument is (a) in the cache and 
+      ** (b) has an outstanding reference, then xUndo is either a no-op
+      ** (if (a) is false) or simply expels the page from the cache (if (b)
+      ** is false).
+      **
+      ** If the upper layer is doing a rollback, it is guaranteed that there
+      ** are no outstanding references to any page other than page 1. And
+      ** page 1 is never written to the log until the transaction is
+      ** committed. As a result, the call to xUndo may not fail.
+      */
+      assert( walFramePgno(pWal, iFrame)!=1 );
+      rc = xUndo(pUndoCtx, walFramePgno(pWal, iFrame));
+    }
+    if( iMax!=pWal->hdr.mxFrame ) walCleanupHash(pWal);
+  }
+  return rc;
+}
+
+/* 
+** Argument aWalData must point to an array of WAL_SAVEPOINT_NDATA u32 
+** values. This function populates the array with values required to 
+** "rollback" the write position of the WAL handle back to the current 
+** point in the event of a savepoint rollback (via WalSavepointUndo()).
+*/
+SQLITE_PRIVATE void sqlite3WalSavepoint(Wal *pWal, u32 *aWalData){
+  assert( pWal->writeLock );
+  aWalData[0] = pWal->hdr.mxFrame;
+  aWalData[1] = pWal->hdr.aFrameCksum[0];
+  aWalData[2] = pWal->hdr.aFrameCksum[1];
+  aWalData[3] = pWal->nCkpt;
+}
+
+/* 
+** Move the write position of the WAL back to the point identified by
+** the values in the aWalData[] array. aWalData must point to an array
+** of WAL_SAVEPOINT_NDATA u32 values that has been previously populated
+** by a call to WalSavepoint().
+*/
+SQLITE_PRIVATE int sqlite3WalSavepointUndo(Wal *pWal, u32 *aWalData){
+  int rc = SQLITE_OK;
+
+  assert( pWal->writeLock );
+  assert( aWalData[3]!=pWal->nCkpt || aWalData[0]<=pWal->hdr.mxFrame );
+
+  if( aWalData[3]!=pWal->nCkpt ){
+    /* This savepoint was opened immediately after the write-transaction
+    ** was started. Right after that, the writer decided to wrap around
+    ** to the start of the log. Update the savepoint values to match.
+    */
+    aWalData[0] = 0;
+    aWalData[3] = pWal->nCkpt;
+  }
+
+  if( aWalData[0]<pWal->hdr.mxFrame ){
+    pWal->hdr.mxFrame = aWalData[0];
+    pWal->hdr.aFrameCksum[0] = aWalData[1];
+    pWal->hdr.aFrameCksum[1] = aWalData[2];
+    walCleanupHash(pWal);
+  }
+
+  return rc;
+}
+
+/*
+** This function is called just before writing a set of frames to the log
+** file (see sqlite3WalFrames()). It checks to see if, instead of appending
+** to the current log file, it is possible to overwrite the start of the
+** existing log file with the new frames (i.e. "reset" the log). If so,
+** it sets pWal->hdr.mxFrame to 0. Otherwise, pWal->hdr.mxFrame is left
+** unchanged.
+**
+** SQLITE_OK is returned if no error is encountered (regardless of whether
+** or not pWal->hdr.mxFrame is modified). An SQLite error code is returned
+** if an error occurs.
+*/
+static int walRestartLog(Wal *pWal){
+  int rc = SQLITE_OK;
+  int cnt;
+
+  if( pWal->readLock==0 ){
+    volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
+    assert( pInfo->nBackfill==pWal->hdr.mxFrame );
+    if( pInfo->nBackfill>0 ){
+      u32 salt1;
+      sqlite3_randomness(4, &salt1);
+      rc = walLockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
+      if( rc==SQLITE_OK ){
+        /* If all readers are using WAL_READ_LOCK(0) (in other words if no
+        ** readers are currently using the WAL), then the transactions
+        ** frames will overwrite the start of the existing log. Update the
+        ** wal-index header to reflect this.
+        **
+        ** In theory it would be Ok to update the cache of the header only
+        ** at this point. But updating the actual wal-index header is also
+        ** safe and means there is no special case for sqlite3WalUndo()
+        ** to handle if this transaction is rolled back.  */
+        walRestartHdr(pWal, salt1);
+        walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
+      }else if( rc!=SQLITE_BUSY ){
+        return rc;
+      }
+    }
+    walUnlockShared(pWal, WAL_READ_LOCK(0));
+    pWal->readLock = -1;
+    cnt = 0;
+    do{
+      int notUsed;
+      rc = walTryBeginRead(pWal, &notUsed, 1, ++cnt);
+    }while( rc==WAL_RETRY );
+    assert( (rc&0xff)!=SQLITE_BUSY ); /* BUSY not possible when useWal==1 */
+    testcase( (rc&0xff)==SQLITE_IOERR );
+    testcase( rc==SQLITE_PROTOCOL );
+    testcase( rc==SQLITE_OK );
+  }
+  return rc;
+}
+
+/*
+** Information about the current state of the WAL file and where
+** the next fsync should occur - passed from sqlite3WalFrames() into
+** walWriteToLog().
+*/
+typedef struct WalWriter {
+  Wal *pWal;                   /* The complete WAL information */
+  sqlite3_file *pFd;           /* The WAL file to which we write */
+  sqlite3_int64 iSyncPoint;    /* Fsync at this offset */
+  int syncFlags;               /* Flags for the fsync */
+  int szPage;                  /* Size of one page */
+} WalWriter;
+
+/*
+** Write iAmt bytes of content into the WAL file beginning at iOffset.
+** Do a sync when crossing the p->iSyncPoint boundary.
+**
+** In other words, if iSyncPoint is in between iOffset and iOffset+iAmt,
+** first write the part before iSyncPoint, then sync, then write the
+** rest.
+*/
+static int walWriteToLog(
+  WalWriter *p,              /* WAL to write to */
+  void *pContent,            /* Content to be written */
+  int iAmt,                  /* Number of bytes to write */
+  sqlite3_int64 iOffset      /* Start writing at this offset */
+){
+  int rc;
+  if( iOffset<p->iSyncPoint && iOffset+iAmt>=p->iSyncPoint ){
+    int iFirstAmt = (int)(p->iSyncPoint - iOffset);
+    rc = sqlite3OsWrite(p->pFd, pContent, iFirstAmt, iOffset);
+    if( rc ) return rc;
+    iOffset += iFirstAmt;
+    iAmt -= iFirstAmt;
+    pContent = (void*)(iFirstAmt + (char*)pContent);
+    assert( p->syncFlags & (SQLITE_SYNC_NORMAL|SQLITE_SYNC_FULL) );
+    rc = sqlite3OsSync(p->pFd, p->syncFlags & SQLITE_SYNC_MASK);
+    if( iAmt==0 || rc ) return rc;
+  }
+  rc = sqlite3OsWrite(p->pFd, pContent, iAmt, iOffset);
+  return rc;
+}
+
+/*
+** Write out a single frame of the WAL
+*/
+static int walWriteOneFrame(
+  WalWriter *p,               /* Where to write the frame */
+  PgHdr *pPage,               /* The page of the frame to be written */
+  int nTruncate,              /* The commit flag.  Usually 0.  >0 for commit */
+  sqlite3_int64 iOffset       /* Byte offset at which to write */
+){
+  int rc;                         /* Result code from subfunctions */
+  void *pData;                    /* Data actually written */
+  u8 aFrame[WAL_FRAME_HDRSIZE];   /* Buffer to assemble frame-header in */
+#if defined(SQLITE_HAS_CODEC)
+  if( (pData = sqlite3PagerCodec(pPage))==0 ) return SQLITE_NOMEM_BKPT;
+#else
+  pData = pPage->pData;
+#endif
+  walEncodeFrame(p->pWal, pPage->pgno, nTruncate, pData, aFrame);
+  rc = walWriteToLog(p, aFrame, sizeof(aFrame), iOffset);
+  if( rc ) return rc;
+  /* Write the page data */
+  rc = walWriteToLog(p, pData, p->szPage, iOffset+sizeof(aFrame));
+  return rc;
+}
+
+/*
+** This function is called as part of committing a transaction within which
+** one or more frames have been overwritten. It updates the checksums for
+** all frames written to the wal file by the current transaction starting
+** with the earliest to have been overwritten.
+**
+** SQLITE_OK is returned if successful, or an SQLite error code otherwise.
+*/
+static int walRewriteChecksums(Wal *pWal, u32 iLast){
+  const int szPage = pWal->szPage;/* Database page size */
+  int rc = SQLITE_OK;             /* Return code */
+  u8 *aBuf;                       /* Buffer to load data from wal file into */
+  u8 aFrame[WAL_FRAME_HDRSIZE];   /* Buffer to assemble frame-headers in */
+  u32 iRead;                      /* Next frame to read from wal file */
+  i64 iCksumOff;
+
+  aBuf = sqlite3_malloc(szPage + WAL_FRAME_HDRSIZE);
+  if( aBuf==0 ) return SQLITE_NOMEM_BKPT;
+
+  /* Find the checksum values to use as input for the recalculating the
+  ** first checksum. If the first frame is frame 1 (implying that the current
+  ** transaction restarted the wal file), these values must be read from the
+  ** wal-file header. Otherwise, read them from the frame header of the
+  ** previous frame.  */
+  assert( pWal->iReCksum>0 );
+  if( pWal->iReCksum==1 ){
+    iCksumOff = 24;
+  }else{
+    iCksumOff = walFrameOffset(pWal->iReCksum-1, szPage) + 16;
+  }
+  rc = sqlite3OsRead(pWal->pWalFd, aBuf, sizeof(u32)*2, iCksumOff);
+  pWal->hdr.aFrameCksum[0] = sqlite3Get4byte(aBuf);
+  pWal->hdr.aFrameCksum[1] = sqlite3Get4byte(&aBuf[sizeof(u32)]);
+
+  iRead = pWal->iReCksum;
+  pWal->iReCksum = 0;
+  for(; rc==SQLITE_OK && iRead<=iLast; iRead++){
+    i64 iOff = walFrameOffset(iRead, szPage);
+    rc = sqlite3OsRead(pWal->pWalFd, aBuf, szPage+WAL_FRAME_HDRSIZE, iOff);
+    if( rc==SQLITE_OK ){
+      u32 iPgno, nDbSize;
+      iPgno = sqlite3Get4byte(aBuf);
+      nDbSize = sqlite3Get4byte(&aBuf[4]);
+
+      walEncodeFrame(pWal, iPgno, nDbSize, &aBuf[WAL_FRAME_HDRSIZE], aFrame);
+      rc = sqlite3OsWrite(pWal->pWalFd, aFrame, sizeof(aFrame), iOff);
+    }
+  }
+
+  sqlite3_free(aBuf);
+  return rc;
+}
+
+/* 
+** Write a set of frames to the log. The caller must hold the write-lock
+** on the log file (obtained using sqlite3WalBeginWriteTransaction()).
+*/
+SQLITE_PRIVATE int sqlite3WalFrames(
+  Wal *pWal,                      /* Wal handle to write to */
+  int szPage,                     /* Database page-size in bytes */
+  PgHdr *pList,                   /* List of dirty pages to write */
+  Pgno nTruncate,                 /* Database size after this commit */
+  int isCommit,                   /* True if this is a commit */
+  int sync_flags                  /* Flags to pass to OsSync() (or 0) */
+){
+  int rc;                         /* Used to catch return codes */
+  u32 iFrame;                     /* Next frame address */
+  PgHdr *p;                       /* Iterator to run through pList with. */
+  PgHdr *pLast = 0;               /* Last frame in list */
+  int nExtra = 0;                 /* Number of extra copies of last page */
+  int szFrame;                    /* The size of a single frame */
+  i64 iOffset;                    /* Next byte to write in WAL file */
+  WalWriter w;                    /* The writer */
+  u32 iFirst = 0;                 /* First frame that may be overwritten */
+  WalIndexHdr *pLive;             /* Pointer to shared header */
+
+  assert( pList );
+  assert( pWal->writeLock );
+
+  /* If this frame set completes a transaction, then nTruncate>0.  If
+  ** nTruncate==0 then this frame set does not complete the transaction. */
+  assert( (isCommit!=0)==(nTruncate!=0) );
+
+#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
+  { int cnt; for(cnt=0, p=pList; p; p=p->pDirty, cnt++){}
+    WALTRACE(("WAL%p: frame write begin. %d frames. mxFrame=%d. %s\n",
+              pWal, cnt, pWal->hdr.mxFrame, isCommit ? "Commit" : "Spill"));
+  }
+#endif
+
+  pLive = (WalIndexHdr*)walIndexHdr(pWal);
+  if( memcmp(&pWal->hdr, (void *)pLive, sizeof(WalIndexHdr))!=0 ){
+    iFirst = pLive->mxFrame+1;
+  }
+
+  /* See if it is possible to write these frames into the start of the
+  ** log file, instead of appending to it at pWal->hdr.mxFrame.
+  */
+  if( SQLITE_OK!=(rc = walRestartLog(pWal)) ){
+    return rc;
+  }
+
+  /* If this is the first frame written into the log, write the WAL
+  ** header to the start of the WAL file. See comments at the top of
+  ** this source file for a description of the WAL header format.
+  */
+  iFrame = pWal->hdr.mxFrame;
+  if( iFrame==0 ){
+    u8 aWalHdr[WAL_HDRSIZE];      /* Buffer to assemble wal-header in */
+    u32 aCksum[2];                /* Checksum for wal-header */
+
+    sqlite3Put4byte(&aWalHdr[0], (WAL_MAGIC | SQLITE_BIGENDIAN));
+    sqlite3Put4byte(&aWalHdr[4], WAL_MAX_VERSION);
+    sqlite3Put4byte(&aWalHdr[8], szPage);
+    sqlite3Put4byte(&aWalHdr[12], pWal->nCkpt);
+    if( pWal->nCkpt==0 ) sqlite3_randomness(8, pWal->hdr.aSalt);
+    memcpy(&aWalHdr[16], pWal->hdr.aSalt, 8);
+    walChecksumBytes(1, aWalHdr, WAL_HDRSIZE-2*4, 0, aCksum);
+    sqlite3Put4byte(&aWalHdr[24], aCksum[0]);
+    sqlite3Put4byte(&aWalHdr[28], aCksum[1]);
+    
+    pWal->szPage = szPage;
+    pWal->hdr.bigEndCksum = SQLITE_BIGENDIAN;
+    pWal->hdr.aFrameCksum[0] = aCksum[0];
+    pWal->hdr.aFrameCksum[1] = aCksum[1];
+    pWal->truncateOnCommit = 1;
+
+    rc = sqlite3OsWrite(pWal->pWalFd, aWalHdr, sizeof(aWalHdr), 0);
+    WALTRACE(("WAL%p: wal-header write %s\n", pWal, rc ? "failed" : "ok"));
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+
+    /* Sync the header (unless SQLITE_IOCAP_SEQUENTIAL is true or unless
+    ** all syncing is turned off by PRAGMA synchronous=OFF).  Otherwise
+    ** an out-of-order write following a WAL restart could result in
+    ** database corruption.  See the ticket:
+    **
+    **     http://localhost:591/sqlite/info/ff5be73dee
+    */
+    if( pWal->syncHeader && sync_flags ){
+      rc = sqlite3OsSync(pWal->pWalFd, sync_flags & SQLITE_SYNC_MASK);
+      if( rc ) return rc;
+    }
+  }
+  assert( (int)pWal->szPage==szPage );
+
+  /* Setup information needed to write frames into the WAL */
+  w.pWal = pWal;
+  w.pFd = pWal->pWalFd;
+  w.iSyncPoint = 0;
+  w.syncFlags = sync_flags;
+  w.szPage = szPage;
+  iOffset = walFrameOffset(iFrame+1, szPage);
+  szFrame = szPage + WAL_FRAME_HDRSIZE;
+
+  /* Write all frames into the log file exactly once */
+  for(p=pList; p; p=p->pDirty){
+    int nDbSize;   /* 0 normally.  Positive == commit flag */
+
+    /* Check if this page has already been written into the wal file by
+    ** the current transaction. If so, overwrite the existing frame and
+    ** set Wal.writeLock to WAL_WRITELOCK_RECKSUM - indicating that 
+    ** checksums must be recomputed when the transaction is committed.  */
+    if( iFirst && (p->pDirty || isCommit==0) ){
+      u32 iWrite = 0;
+      VVA_ONLY(rc =) sqlite3WalFindFrame(pWal, p->pgno, &iWrite);
+      assert( rc==SQLITE_OK || iWrite==0 );
+      if( iWrite>=iFirst ){
+        i64 iOff = walFrameOffset(iWrite, szPage) + WAL_FRAME_HDRSIZE;
+        void *pData;
+        if( pWal->iReCksum==0 || iWrite<pWal->iReCksum ){
+          pWal->iReCksum = iWrite;
+        }
+#if defined(SQLITE_HAS_CODEC)
+        if( (pData = sqlite3PagerCodec(p))==0 ) return SQLITE_NOMEM;
+#else
+        pData = p->pData;
+#endif
+        rc = sqlite3OsWrite(pWal->pWalFd, pData, szPage, iOff);
+        if( rc ) return rc;
+        p->flags &= ~PGHDR_WAL_APPEND;
+        continue;
+      }
+    }
+
+    iFrame++;
+    assert( iOffset==walFrameOffset(iFrame, szPage) );
+    nDbSize = (isCommit && p->pDirty==0) ? nTruncate : 0;
+    rc = walWriteOneFrame(&w, p, nDbSize, iOffset);
+    if( rc ) return rc;
+    pLast = p;
+    iOffset += szFrame;
+    p->flags |= PGHDR_WAL_APPEND;
+  }
+
+  /* Recalculate checksums within the wal file if required. */
+  if( isCommit && pWal->iReCksum ){
+    rc = walRewriteChecksums(pWal, iFrame);
+    if( rc ) return rc;
+  }
+
+  /* If this is the end of a transaction, then we might need to pad
+  ** the transaction and/or sync the WAL file.
+  **
+  ** Padding and syncing only occur if this set of frames complete a
+  ** transaction and if PRAGMA synchronous=FULL.  If synchronous==NORMAL
+  ** or synchronous==OFF, then no padding or syncing are needed.
+  **
+  ** If SQLITE_IOCAP_POWERSAFE_OVERWRITE is defined, then padding is not
+  ** needed and only the sync is done.  If padding is needed, then the
+  ** final frame is repeated (with its commit mark) until the next sector
+  ** boundary is crossed.  Only the part of the WAL prior to the last
+  ** sector boundary is synced; the part of the last frame that extends
+  ** past the sector boundary is written after the sync.
+  */
+  if( isCommit && (sync_flags & WAL_SYNC_TRANSACTIONS)!=0 ){
+    int bSync = 1;
+    if( pWal->padToSectorBoundary ){
+      int sectorSize = sqlite3SectorSize(pWal->pWalFd);
+      w.iSyncPoint = ((iOffset+sectorSize-1)/sectorSize)*sectorSize;
+      bSync = (w.iSyncPoint==iOffset);
+      testcase( bSync );
+      while( iOffset<w.iSyncPoint ){
+        rc = walWriteOneFrame(&w, pLast, nTruncate, iOffset);
+        if( rc ) return rc;
+        iOffset += szFrame;
+        nExtra++;
+      }
+    }
+    if( bSync ){
+      assert( rc==SQLITE_OK );
+      rc = sqlite3OsSync(w.pFd, sync_flags & SQLITE_SYNC_MASK);
+    }
+  }
+
+  /* If this frame set completes the first transaction in the WAL and
+  ** if PRAGMA journal_size_limit is set, then truncate the WAL to the
+  ** journal size limit, if possible.
+  */
+  if( isCommit && pWal->truncateOnCommit && pWal->mxWalSize>=0 ){
+    i64 sz = pWal->mxWalSize;
+    if( walFrameOffset(iFrame+nExtra+1, szPage)>pWal->mxWalSize ){
+      sz = walFrameOffset(iFrame+nExtra+1, szPage);
+    }
+    walLimitSize(pWal, sz);
+    pWal->truncateOnCommit = 0;
+  }
+
+  /* Append data to the wal-index. It is not necessary to lock the 
+  ** wal-index to do this as the SQLITE_SHM_WRITE lock held on the wal-index
+  ** guarantees that there are no other writers, and no data that may
+  ** be in use by existing readers is being overwritten.
+  */
+  iFrame = pWal->hdr.mxFrame;
+  for(p=pList; p && rc==SQLITE_OK; p=p->pDirty){
+    if( (p->flags & PGHDR_WAL_APPEND)==0 ) continue;
+    iFrame++;
+    rc = walIndexAppend(pWal, iFrame, p->pgno);
+  }
+  while( rc==SQLITE_OK && nExtra>0 ){
+    iFrame++;
+    nExtra--;
+    rc = walIndexAppend(pWal, iFrame, pLast->pgno);
+  }
+
+  if( rc==SQLITE_OK ){
+    /* Update the private copy of the header. */
+    pWal->hdr.szPage = (u16)((szPage&0xff00) | (szPage>>16));
+    testcase( szPage<=32768 );
+    testcase( szPage>=65536 );
+    pWal->hdr.mxFrame = iFrame;
+    if( isCommit ){
+      pWal->hdr.iChange++;
+      pWal->hdr.nPage = nTruncate;
+    }
+    /* If this is a commit, update the wal-index header too. */
+    if( isCommit ){
+      walIndexWriteHdr(pWal);
+      pWal->iCallback = iFrame;
+    }
+  }
+
+  WALTRACE(("WAL%p: frame write %s\n", pWal, rc ? "failed" : "ok"));
+  return rc;
+}
+
+/* 
+** This routine is called to implement sqlite3_wal_checkpoint() and
+** related interfaces.
+**
+** Obtain a CHECKPOINT lock and then backfill as much information as
+** we can from WAL into the database.
+**
+** If parameter xBusy is not NULL, it is a pointer to a busy-handler
+** callback. In this case this function runs a blocking checkpoint.
+*/
+SQLITE_PRIVATE int sqlite3WalCheckpoint(
+  Wal *pWal,                      /* Wal connection */
+  int eMode,                      /* PASSIVE, FULL, RESTART, or TRUNCATE */
+  int (*xBusy)(void*),            /* Function to call when busy */
+  void *pBusyArg,                 /* Context argument for xBusyHandler */
+  int sync_flags,                 /* Flags to sync db file with (or 0) */
+  int nBuf,                       /* Size of temporary buffer */
+  u8 *zBuf,                       /* Temporary buffer to use */
+  int *pnLog,                     /* OUT: Number of frames in WAL */
+  int *pnCkpt                     /* OUT: Number of backfilled frames in WAL */
+){
+  int rc;                         /* Return code */
+  int isChanged = 0;              /* True if a new wal-index header is loaded */
+  int eMode2 = eMode;             /* Mode to pass to walCheckpoint() */
+  int (*xBusy2)(void*) = xBusy;   /* Busy handler for eMode2 */
+
+  assert( pWal->ckptLock==0 );
+  assert( pWal->writeLock==0 );
+
+  /* EVIDENCE-OF: R-62920-47450 The busy-handler callback is never invoked
+  ** in the SQLITE_CHECKPOINT_PASSIVE mode. */
+  assert( eMode!=SQLITE_CHECKPOINT_PASSIVE || xBusy==0 );
+
+  if( pWal->readOnly ) return SQLITE_READONLY;
+  WALTRACE(("WAL%p: checkpoint begins\n", pWal));
+
+  /* IMPLEMENTATION-OF: R-62028-47212 All calls obtain an exclusive 
+  ** "checkpoint" lock on the database file. */
+  rc = walLockExclusive(pWal, WAL_CKPT_LOCK, 1);
+  if( rc ){
+    /* EVIDENCE-OF: R-10421-19736 If any other process is running a
+    ** checkpoint operation at the same time, the lock cannot be obtained and
+    ** SQLITE_BUSY is returned.
+    ** EVIDENCE-OF: R-53820-33897 Even if there is a busy-handler configured,
+    ** it will not be invoked in this case.
+    */
+    testcase( rc==SQLITE_BUSY );
+    testcase( xBusy!=0 );
+    return rc;
+  }
+  pWal->ckptLock = 1;
+
+  /* IMPLEMENTATION-OF: R-59782-36818 The SQLITE_CHECKPOINT_FULL, RESTART and
+  ** TRUNCATE modes also obtain the exclusive "writer" lock on the database
+  ** file.
+  **
+  ** EVIDENCE-OF: R-60642-04082 If the writer lock cannot be obtained
+  ** immediately, and a busy-handler is configured, it is invoked and the
+  ** writer lock retried until either the busy-handler returns 0 or the
+  ** lock is successfully obtained.
+  */
+  if( eMode!=SQLITE_CHECKPOINT_PASSIVE ){
+    rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_WRITE_LOCK, 1);
+    if( rc==SQLITE_OK ){
+      pWal->writeLock = 1;
+    }else if( rc==SQLITE_BUSY ){
+      eMode2 = SQLITE_CHECKPOINT_PASSIVE;
+      xBusy2 = 0;
+      rc = SQLITE_OK;
+    }
+  }
+
+  /* Read the wal-index header. */
+  if( rc==SQLITE_OK ){
+    rc = walIndexReadHdr(pWal, &isChanged);
+    if( isChanged && pWal->pDbFd->pMethods->iVersion>=3 ){
+      sqlite3OsUnfetch(pWal->pDbFd, 0, 0);
+    }
+  }
+
+  /* Copy data from the log to the database file. */
+  if( rc==SQLITE_OK ){
+
+    if( pWal->hdr.mxFrame && walPagesize(pWal)!=nBuf ){
+      rc = SQLITE_CORRUPT_BKPT;
+    }else{
+      rc = walCheckpoint(pWal, eMode2, xBusy2, pBusyArg, sync_flags, zBuf);
+    }
+
+    /* If no error occurred, set the output variables. */
+    if( rc==SQLITE_OK || rc==SQLITE_BUSY ){
+      if( pnLog ) *pnLog = (int)pWal->hdr.mxFrame;
+      if( pnCkpt ) *pnCkpt = (int)(walCkptInfo(pWal)->nBackfill);
+    }
+  }
+
+  if( isChanged ){
+    /* If a new wal-index header was loaded before the checkpoint was 
+    ** performed, then the pager-cache associated with pWal is now
+    ** out of date. So zero the cached wal-index header to ensure that
+    ** next time the pager opens a snapshot on this database it knows that
+    ** the cache needs to be reset.
+    */
+    memset(&pWal->hdr, 0, sizeof(WalIndexHdr));
+  }
+
+  /* Release the locks. */
+  sqlite3WalEndWriteTransaction(pWal);
+  walUnlockExclusive(pWal, WAL_CKPT_LOCK, 1);
+  pWal->ckptLock = 0;
+  WALTRACE(("WAL%p: checkpoint %s\n", pWal, rc ? "failed" : "ok"));
+  return (rc==SQLITE_OK && eMode!=eMode2 ? SQLITE_BUSY : rc);
+}
+
+/* Return the value to pass to a sqlite3_wal_hook callback, the
+** number of frames in the WAL at the point of the last commit since
+** sqlite3WalCallback() was called.  If no commits have occurred since
+** the last call, then return 0.
+*/
+SQLITE_PRIVATE int sqlite3WalCallback(Wal *pWal){
+  u32 ret = 0;
+  if( pWal ){
+    ret = pWal->iCallback;
+    pWal->iCallback = 0;
+  }
+  return (int)ret;
+}
+
+/*
+** This function is called to change the WAL subsystem into or out
+** of locking_mode=EXCLUSIVE.
+**
+** If op is zero, then attempt to change from locking_mode=EXCLUSIVE
+** into locking_mode=NORMAL.  This means that we must acquire a lock
+** on the pWal->readLock byte.  If the WAL is already in locking_mode=NORMAL
+** or if the acquisition of the lock fails, then return 0.  If the
+** transition out of exclusive-mode is successful, return 1.  This
+** operation must occur while the pager is still holding the exclusive
+** lock on the main database file.
+**
+** If op is one, then change from locking_mode=NORMAL into 
+** locking_mode=EXCLUSIVE.  This means that the pWal->readLock must
+** be released.  Return 1 if the transition is made and 0 if the
+** WAL is already in exclusive-locking mode - meaning that this
+** routine is a no-op.  The pager must already hold the exclusive lock
+** on the main database file before invoking this operation.
+**
+** If op is negative, then do a dry-run of the op==1 case but do
+** not actually change anything. The pager uses this to see if it
+** should acquire the database exclusive lock prior to invoking
+** the op==1 case.
+*/
+SQLITE_PRIVATE int sqlite3WalExclusiveMode(Wal *pWal, int op){
+  int rc;
+  assert( pWal->writeLock==0 );
+  assert( pWal->exclusiveMode!=WAL_HEAPMEMORY_MODE || op==-1 );
+
+  /* pWal->readLock is usually set, but might be -1 if there was a 
+  ** prior error while attempting to acquire are read-lock. This cannot 
+  ** happen if the connection is actually in exclusive mode (as no xShmLock
+  ** locks are taken in this case). Nor should the pager attempt to
+  ** upgrade to exclusive-mode following such an error.
+  */
+  assert( pWal->readLock>=0 || pWal->lockError );
+  assert( pWal->readLock>=0 || (op<=0 && pWal->exclusiveMode==0) );
+
+  if( op==0 ){
+    if( pWal->exclusiveMode ){
+      pWal->exclusiveMode = 0;
+      if( walLockShared(pWal, WAL_READ_LOCK(pWal->readLock))!=SQLITE_OK ){
+        pWal->exclusiveMode = 1;
+      }
+      rc = pWal->exclusiveMode==0;
+    }else{
+      /* Already in locking_mode=NORMAL */
+      rc = 0;
+    }
+  }else if( op>0 ){
+    assert( pWal->exclusiveMode==0 );
+    assert( pWal->readLock>=0 );
+    walUnlockShared(pWal, WAL_READ_LOCK(pWal->readLock));
+    pWal->exclusiveMode = 1;
+    rc = 1;
+  }else{
+    rc = pWal->exclusiveMode==0;
+  }
+  return rc;
+}
+
+/* 
+** Return true if the argument is non-NULL and the WAL module is using
+** heap-memory for the wal-index. Otherwise, if the argument is NULL or the
+** WAL module is using shared-memory, return false. 
+*/
+SQLITE_PRIVATE int sqlite3WalHeapMemory(Wal *pWal){
+  return (pWal && pWal->exclusiveMode==WAL_HEAPMEMORY_MODE );
+}
+
+#ifdef SQLITE_ENABLE_SNAPSHOT
+/* Create a snapshot object.  The content of a snapshot is opaque to
+** every other subsystem, so the WAL module can put whatever it needs
+** in the object.
+*/
+SQLITE_PRIVATE int sqlite3WalSnapshotGet(Wal *pWal, sqlite3_snapshot **ppSnapshot){
+  int rc = SQLITE_OK;
+  WalIndexHdr *pRet;
+
+  assert( pWal->readLock>=0 && pWal->writeLock==0 );
+
+  pRet = (WalIndexHdr*)sqlite3_malloc(sizeof(WalIndexHdr));
+  if( pRet==0 ){
+    rc = SQLITE_NOMEM_BKPT;
+  }else{
+    memcpy(pRet, &pWal->hdr, sizeof(WalIndexHdr));
+    *ppSnapshot = (sqlite3_snapshot*)pRet;
+  }
+
+  return rc;
+}
+
+/* Try to open on pSnapshot when the next read-transaction starts
+*/
+SQLITE_PRIVATE void sqlite3WalSnapshotOpen(Wal *pWal, sqlite3_snapshot *pSnapshot){
+  pWal->pSnapshot = (WalIndexHdr*)pSnapshot;
+}
+
+/* 
+** Return a +ve value if snapshot p1 is newer than p2. A -ve value if
+** p1 is older than p2 and zero if p1 and p2 are the same snapshot.
+*/
+SQLITE_API int sqlite3_snapshot_cmp(sqlite3_snapshot *p1, sqlite3_snapshot *p2){
+  WalIndexHdr *pHdr1 = (WalIndexHdr*)p1;
+  WalIndexHdr *pHdr2 = (WalIndexHdr*)p2;
+
+  /* aSalt[0] is a copy of the value stored in the wal file header. It
+  ** is incremented each time the wal file is restarted.  */
+  if( pHdr1->aSalt[0]<pHdr2->aSalt[0] ) return -1;
+  if( pHdr1->aSalt[0]>pHdr2->aSalt[0] ) return +1;
+  if( pHdr1->mxFrame<pHdr2->mxFrame ) return -1;
+  if( pHdr1->mxFrame>pHdr2->mxFrame ) return +1;
+  return 0;
+}
+#endif /* SQLITE_ENABLE_SNAPSHOT */
+
+#ifdef SQLITE_ENABLE_ZIPVFS
+/*
+** If the argument is not NULL, it points to a Wal object that holds a
+** read-lock. This function returns the database page-size if it is known,
+** or zero if it is not (or if pWal is NULL).
+*/
+SQLITE_PRIVATE int sqlite3WalFramesize(Wal *pWal){
+  assert( pWal==0 || pWal->readLock>=0 );
+  return (pWal ? pWal->szPage : 0);
+}
+#endif
+
+/* Return the sqlite3_file object for the WAL file
+*/
+SQLITE_PRIVATE sqlite3_file *sqlite3WalFile(Wal *pWal){
+  return pWal->pWalFd;
+}
+
+#endif /* #ifndef SQLITE_OMIT_WAL */
+
+/************** End of wal.c *************************************************/
+/************** Begin file btmutex.c *****************************************/
+/*
+** 2007 August 27
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains code used to implement mutexes on Btree objects.
+** This code really belongs in btree.c.  But btree.c is getting too
+** big and we want to break it down some.  This packaged seemed like
+** a good breakout.
+*/
+/* #include "btreeInt.h" */
+#ifndef SQLITE_OMIT_SHARED_CACHE
+#if SQLITE_THREADSAFE
+
+/*
+** Obtain the BtShared mutex associated with B-Tree handle p. Also,
+** set BtShared.db to the database handle associated with p and the
+** p->locked boolean to true.
+*/
+static void lockBtreeMutex(Btree *p){
+  assert( p->locked==0 );
+  assert( sqlite3_mutex_notheld(p->pBt->mutex) );
+  assert( sqlite3_mutex_held(p->db->mutex) );
+
+  sqlite3_mutex_enter(p->pBt->mutex);
+  p->pBt->db = p->db;
+  p->locked = 1;
+}
+
+/*
+** Release the BtShared mutex associated with B-Tree handle p and
+** clear the p->locked boolean.
+*/
+static void SQLITE_NOINLINE unlockBtreeMutex(Btree *p){
+  BtShared *pBt = p->pBt;
+  assert( p->locked==1 );
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  assert( p->db==pBt->db );
+
+  sqlite3_mutex_leave(pBt->mutex);
+  p->locked = 0;
+}
+
+/* Forward reference */
+static void SQLITE_NOINLINE btreeLockCarefully(Btree *p);
+
+/*
+** Enter a mutex on the given BTree object.
+**
+** If the object is not sharable, then no mutex is ever required
+** and this routine is a no-op.  The underlying mutex is non-recursive.
+** But we keep a reference count in Btree.wantToLock so the behavior
+** of this interface is recursive.
+**
+** To avoid deadlocks, multiple Btrees are locked in the same order
+** by all database connections.  The p->pNext is a list of other
+** Btrees belonging to the same database connection as the p Btree
+** which need to be locked after p.  If we cannot get a lock on
+** p, then first unlock all of the others on p->pNext, then wait
+** for the lock to become available on p, then relock all of the
+** subsequent Btrees that desire a lock.
+*/
+SQLITE_PRIVATE void sqlite3BtreeEnter(Btree *p){
+  /* Some basic sanity checking on the Btree.  The list of Btrees
+  ** connected by pNext and pPrev should be in sorted order by
+  ** Btree.pBt value. All elements of the list should belong to
+  ** the same connection. Only shared Btrees are on the list. */
+  assert( p->pNext==0 || p->pNext->pBt>p->pBt );
+  assert( p->pPrev==0 || p->pPrev->pBt<p->pBt );
+  assert( p->pNext==0 || p->pNext->db==p->db );
+  assert( p->pPrev==0 || p->pPrev->db==p->db );
+  assert( p->sharable || (p->pNext==0 && p->pPrev==0) );
+
+  /* Check for locking consistency */
+  assert( !p->locked || p->wantToLock>0 );
+  assert( p->sharable || p->wantToLock==0 );
+
+  /* We should already hold a lock on the database connection */
+  assert( sqlite3_mutex_held(p->db->mutex) );
+
+  /* Unless the database is sharable and unlocked, then BtShared.db
+  ** should already be set correctly. */
+  assert( (p->locked==0 && p->sharable) || p->pBt->db==p->db );
+
+  if( !p->sharable ) return;
+  p->wantToLock++;
+  if( p->locked ) return;
+  btreeLockCarefully(p);
+}
+
+/* This is a helper function for sqlite3BtreeLock(). By moving
+** complex, but seldom used logic, out of sqlite3BtreeLock() and
+** into this routine, we avoid unnecessary stack pointer changes
+** and thus help the sqlite3BtreeLock() routine to run much faster
+** in the common case.
+*/
+static void SQLITE_NOINLINE btreeLockCarefully(Btree *p){
+  Btree *pLater;
+
+  /* In most cases, we should be able to acquire the lock we
+  ** want without having to go through the ascending lock
+  ** procedure that follows.  Just be sure not to block.
+  */
+  if( sqlite3_mutex_try(p->pBt->mutex)==SQLITE_OK ){
+    p->pBt->db = p->db;
+    p->locked = 1;
+    return;
+  }
+
+  /* To avoid deadlock, first release all locks with a larger
+  ** BtShared address.  Then acquire our lock.  Then reacquire
+  ** the other BtShared locks that we used to hold in ascending
+  ** order.
+  */
+  for(pLater=p->pNext; pLater; pLater=pLater->pNext){
+    assert( pLater->sharable );
+    assert( pLater->pNext==0 || pLater->pNext->pBt>pLater->pBt );
+    assert( !pLater->locked || pLater->wantToLock>0 );
+    if( pLater->locked ){
+      unlockBtreeMutex(pLater);
+    }
+  }
+  lockBtreeMutex(p);
+  for(pLater=p->pNext; pLater; pLater=pLater->pNext){
+    if( pLater->wantToLock ){
+      lockBtreeMutex(pLater);
+    }
+  }
+}
+
+
+/*
+** Exit the recursive mutex on a Btree.
+*/
+SQLITE_PRIVATE void sqlite3BtreeLeave(Btree *p){
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  if( p->sharable ){
+    assert( p->wantToLock>0 );
+    p->wantToLock--;
+    if( p->wantToLock==0 ){
+      unlockBtreeMutex(p);
+    }
+  }
+}
+
+#ifndef NDEBUG
+/*
+** Return true if the BtShared mutex is held on the btree, or if the
+** B-Tree is not marked as sharable.
+**
+** This routine is used only from within assert() statements.
+*/
+SQLITE_PRIVATE int sqlite3BtreeHoldsMutex(Btree *p){
+  assert( p->sharable==0 || p->locked==0 || p->wantToLock>0 );
+  assert( p->sharable==0 || p->locked==0 || p->db==p->pBt->db );
+  assert( p->sharable==0 || p->locked==0 || sqlite3_mutex_held(p->pBt->mutex) );
+  assert( p->sharable==0 || p->locked==0 || sqlite3_mutex_held(p->db->mutex) );
+
+  return (p->sharable==0 || p->locked);
+}
+#endif
+
+
+/*
+** Enter the mutex on every Btree associated with a database
+** connection.  This is needed (for example) prior to parsing
+** a statement since we will be comparing table and column names
+** against all schemas and we do not want those schemas being
+** reset out from under us.
+**
+** There is a corresponding leave-all procedures.
+**
+** Enter the mutexes in accending order by BtShared pointer address
+** to avoid the possibility of deadlock when two threads with
+** two or more btrees in common both try to lock all their btrees
+** at the same instant.
+*/
+SQLITE_PRIVATE void sqlite3BtreeEnterAll(sqlite3 *db){
+  int i;
+  Btree *p;
+  assert( sqlite3_mutex_held(db->mutex) );
+  for(i=0; i<db->nDb; i++){
+    p = db->aDb[i].pBt;
+    if( p ) sqlite3BtreeEnter(p);
+  }
+}
+SQLITE_PRIVATE void sqlite3BtreeLeaveAll(sqlite3 *db){
+  int i;
+  Btree *p;
+  assert( sqlite3_mutex_held(db->mutex) );
+  for(i=0; i<db->nDb; i++){
+    p = db->aDb[i].pBt;
+    if( p ) sqlite3BtreeLeave(p);
+  }
+}
+
+#ifndef NDEBUG
+/*
+** Return true if the current thread holds the database connection
+** mutex and all required BtShared mutexes.
+**
+** This routine is used inside assert() statements only.
+*/
+SQLITE_PRIVATE int sqlite3BtreeHoldsAllMutexes(sqlite3 *db){
+  int i;
+  if( !sqlite3_mutex_held(db->mutex) ){
+    return 0;
+  }
+  for(i=0; i<db->nDb; i++){
+    Btree *p;
+    p = db->aDb[i].pBt;
+    if( p && p->sharable &&
+         (p->wantToLock==0 || !sqlite3_mutex_held(p->pBt->mutex)) ){
+      return 0;
+    }
+  }
+  return 1;
+}
+#endif /* NDEBUG */
+
+#ifndef NDEBUG
+/*
+** Return true if the correct mutexes are held for accessing the
+** db->aDb[iDb].pSchema structure.  The mutexes required for schema
+** access are:
+**
+**   (1) The mutex on db
+**   (2) if iDb!=1, then the mutex on db->aDb[iDb].pBt.
+**
+** If pSchema is not NULL, then iDb is computed from pSchema and
+** db using sqlite3SchemaToIndex().
+*/
+SQLITE_PRIVATE int sqlite3SchemaMutexHeld(sqlite3 *db, int iDb, Schema *pSchema){
+  Btree *p;
+  assert( db!=0 );
+  if( pSchema ) iDb = sqlite3SchemaToIndex(db, pSchema);
+  assert( iDb>=0 && iDb<db->nDb );
+  if( !sqlite3_mutex_held(db->mutex) ) return 0;
+  if( iDb==1 ) return 1;
+  p = db->aDb[iDb].pBt;
+  assert( p!=0 );
+  return p->sharable==0 || p->locked==1;
+}
+#endif /* NDEBUG */
+
+#else /* SQLITE_THREADSAFE>0 above.  SQLITE_THREADSAFE==0 below */
+/*
+** The following are special cases for mutex enter routines for use
+** in single threaded applications that use shared cache.  Except for
+** these two routines, all mutex operations are no-ops in that case and
+** are null #defines in btree.h.
+**
+** If shared cache is disabled, then all btree mutex routines, including
+** the ones below, are no-ops and are null #defines in btree.h.
+*/
+
+SQLITE_PRIVATE void sqlite3BtreeEnter(Btree *p){
+  p->pBt->db = p->db;
+}
+SQLITE_PRIVATE void sqlite3BtreeEnterAll(sqlite3 *db){
+  int i;
+  for(i=0; i<db->nDb; i++){
+    Btree *p = db->aDb[i].pBt;
+    if( p ){
+      p->pBt->db = p->db;
+    }
+  }
+}
+#endif /* if SQLITE_THREADSAFE */
+
+#ifndef SQLITE_OMIT_INCRBLOB
+/*
+** Enter a mutex on a Btree given a cursor owned by that Btree. 
+**
+** These entry points are used by incremental I/O only. Enter() is required 
+** any time OMIT_SHARED_CACHE is not defined, regardless of whether or not 
+** the build is threadsafe. Leave() is only required by threadsafe builds.
+*/
+SQLITE_PRIVATE void sqlite3BtreeEnterCursor(BtCursor *pCur){
+  sqlite3BtreeEnter(pCur->pBtree);
+}
+# if SQLITE_THREADSAFE
+SQLITE_PRIVATE void sqlite3BtreeLeaveCursor(BtCursor *pCur){
+  sqlite3BtreeLeave(pCur->pBtree);
+}
+# endif
+#endif /* ifndef SQLITE_OMIT_INCRBLOB */
+
+#endif /* ifndef SQLITE_OMIT_SHARED_CACHE */
+
+/************** End of btmutex.c *********************************************/
+/************** Begin file btree.c *******************************************/
+/*
+** 2004 April 6
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file implements an external (disk-based) database using BTrees.
+** See the header comment on "btreeInt.h" for additional information.
+** Including a description of file format and an overview of operation.
+*/
+/* #include "btreeInt.h" */
+
+/*
+** The header string that appears at the beginning of every
+** SQLite database.
+*/
+static const char zMagicHeader[] = SQLITE_FILE_HEADER;
+
+/*
+** Set this global variable to 1 to enable tracing using the TRACE
+** macro.
+*/
+#if 0
+int sqlite3BtreeTrace=1;  /* True to enable tracing */
+# define TRACE(X)  if(sqlite3BtreeTrace){printf X;fflush(stdout);}
+#else
+# define TRACE(X)
+#endif
+
+/*
+** Extract a 2-byte big-endian integer from an array of unsigned bytes.
+** But if the value is zero, make it 65536.
+**
+** This routine is used to extract the "offset to cell content area" value
+** from the header of a btree page.  If the page size is 65536 and the page
+** is empty, the offset should be 65536, but the 2-byte value stores zero.
+** This routine makes the necessary adjustment to 65536.
+*/
+#define get2byteNotZero(X)  (((((int)get2byte(X))-1)&0xffff)+1)
+
+/*
+** Values passed as the 5th argument to allocateBtreePage()
+*/
+#define BTALLOC_ANY   0           /* Allocate any page */
+#define BTALLOC_EXACT 1           /* Allocate exact page if possible */
+#define BTALLOC_LE    2           /* Allocate any page <= the parameter */
+
+/*
+** Macro IfNotOmitAV(x) returns (x) if SQLITE_OMIT_AUTOVACUUM is not 
+** defined, or 0 if it is. For example:
+**
+**   bIncrVacuum = IfNotOmitAV(pBtShared->incrVacuum);
+*/
+#ifndef SQLITE_OMIT_AUTOVACUUM
+#define IfNotOmitAV(expr) (expr)
+#else
+#define IfNotOmitAV(expr) 0
+#endif
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+/*
+** A list of BtShared objects that are eligible for participation
+** in shared cache.  This variable has file scope during normal builds,
+** but the test harness needs to access it so we make it global for 
+** test builds.
+**
+** Access to this variable is protected by SQLITE_MUTEX_STATIC_MASTER.
+*/
+#ifdef SQLITE_TEST
+SQLITE_PRIVATE BtShared *SQLITE_WSD sqlite3SharedCacheList = 0;
+#else
+static BtShared *SQLITE_WSD sqlite3SharedCacheList = 0;
+#endif
+#endif /* SQLITE_OMIT_SHARED_CACHE */
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+/*
+** Enable or disable the shared pager and schema features.
+**
+** This routine has no effect on existing database connections.
+** The shared cache setting effects only future calls to
+** sqlite3_open(), sqlite3_open16(), or sqlite3_open_v2().
+*/
+SQLITE_API int sqlite3_enable_shared_cache(int enable){
+  sqlite3GlobalConfig.sharedCacheEnabled = enable;
+  return SQLITE_OK;
+}
+#endif
+
+
+
+#ifdef SQLITE_OMIT_SHARED_CACHE
+  /*
+  ** The functions querySharedCacheTableLock(), setSharedCacheTableLock(),
+  ** and clearAllSharedCacheTableLocks()
+  ** manipulate entries in the BtShared.pLock linked list used to store
+  ** shared-cache table level locks. If the library is compiled with the
+  ** shared-cache feature disabled, then there is only ever one user
+  ** of each BtShared structure and so this locking is not necessary. 
+  ** So define the lock related functions as no-ops.
+  */
+  #define querySharedCacheTableLock(a,b,c) SQLITE_OK
+  #define setSharedCacheTableLock(a,b,c) SQLITE_OK
+  #define clearAllSharedCacheTableLocks(a)
+  #define downgradeAllSharedCacheTableLocks(a)
+  #define hasSharedCacheTableLock(a,b,c,d) 1
+  #define hasReadConflicts(a, b) 0
+#endif
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+
+#ifdef SQLITE_DEBUG
+/*
+**** This function is only used as part of an assert() statement. ***
+**
+** Check to see if pBtree holds the required locks to read or write to the 
+** table with root page iRoot.   Return 1 if it does and 0 if not.
+**
+** For example, when writing to a table with root-page iRoot via 
+** Btree connection pBtree:
+**
+**    assert( hasSharedCacheTableLock(pBtree, iRoot, 0, WRITE_LOCK) );
+**
+** When writing to an index that resides in a sharable database, the 
+** caller should have first obtained a lock specifying the root page of
+** the corresponding table. This makes things a bit more complicated,
+** as this module treats each table as a separate structure. To determine
+** the table corresponding to the index being written, this
+** function has to search through the database schema.
+**
+** Instead of a lock on the table/index rooted at page iRoot, the caller may
+** hold a write-lock on the schema table (root page 1). This is also
+** acceptable.
+*/
+static int hasSharedCacheTableLock(
+  Btree *pBtree,         /* Handle that must hold lock */
+  Pgno iRoot,            /* Root page of b-tree */
+  int isIndex,           /* True if iRoot is the root of an index b-tree */
+  int eLockType          /* Required lock type (READ_LOCK or WRITE_LOCK) */
+){
+  Schema *pSchema = (Schema *)pBtree->pBt->pSchema;
+  Pgno iTab = 0;
+  BtLock *pLock;
+
+  /* If this database is not shareable, or if the client is reading
+  ** and has the read-uncommitted flag set, then no lock is required. 
+  ** Return true immediately.
+  */
+  if( (pBtree->sharable==0)
+   || (eLockType==READ_LOCK && (pBtree->db->flags & SQLITE_ReadUncommitted))
+  ){
+    return 1;
+  }
+
+  /* If the client is reading  or writing an index and the schema is
+  ** not loaded, then it is too difficult to actually check to see if
+  ** the correct locks are held.  So do not bother - just return true.
+  ** This case does not come up very often anyhow.
+  */
+  if( isIndex && (!pSchema || (pSchema->schemaFlags&DB_SchemaLoaded)==0) ){
+    return 1;
+  }
+
+  /* Figure out the root-page that the lock should be held on. For table
+  ** b-trees, this is just the root page of the b-tree being read or
+  ** written. For index b-trees, it is the root page of the associated
+  ** table.  */
+  if( isIndex ){
+    HashElem *p;
+    for(p=sqliteHashFirst(&pSchema->idxHash); p; p=sqliteHashNext(p)){
+      Index *pIdx = (Index *)sqliteHashData(p);
+      if( pIdx->tnum==(int)iRoot ){
+        if( iTab ){
+          /* Two or more indexes share the same root page.  There must
+          ** be imposter tables.  So just return true.  The assert is not
+          ** useful in that case. */
+          return 1;
+        }
+        iTab = pIdx->pTable->tnum;
+      }
+    }
+  }else{
+    iTab = iRoot;
+  }
+
+  /* Search for the required lock. Either a write-lock on root-page iTab, a 
+  ** write-lock on the schema table, or (if the client is reading) a
+  ** read-lock on iTab will suffice. Return 1 if any of these are found.  */
+  for(pLock=pBtree->pBt->pLock; pLock; pLock=pLock->pNext){
+    if( pLock->pBtree==pBtree 
+     && (pLock->iTable==iTab || (pLock->eLock==WRITE_LOCK && pLock->iTable==1))
+     && pLock->eLock>=eLockType 
+    ){
+      return 1;
+    }
+  }
+
+  /* Failed to find the required lock. */
+  return 0;
+}
+#endif /* SQLITE_DEBUG */
+
+#ifdef SQLITE_DEBUG
+/*
+**** This function may be used as part of assert() statements only. ****
+**
+** Return true if it would be illegal for pBtree to write into the
+** table or index rooted at iRoot because other shared connections are
+** simultaneously reading that same table or index.
+**
+** It is illegal for pBtree to write if some other Btree object that
+** shares the same BtShared object is currently reading or writing
+** the iRoot table.  Except, if the other Btree object has the
+** read-uncommitted flag set, then it is OK for the other object to
+** have a read cursor.
+**
+** For example, before writing to any part of the table or index
+** rooted at page iRoot, one should call:
+**
+**    assert( !hasReadConflicts(pBtree, iRoot) );
+*/
+static int hasReadConflicts(Btree *pBtree, Pgno iRoot){
+  BtCursor *p;
+  for(p=pBtree->pBt->pCursor; p; p=p->pNext){
+    if( p->pgnoRoot==iRoot 
+     && p->pBtree!=pBtree
+     && 0==(p->pBtree->db->flags & SQLITE_ReadUncommitted)
+    ){
+      return 1;
+    }
+  }
+  return 0;
+}
+#endif    /* #ifdef SQLITE_DEBUG */
+
+/*
+** Query to see if Btree handle p may obtain a lock of type eLock 
+** (READ_LOCK or WRITE_LOCK) on the table with root-page iTab. Return
+** SQLITE_OK if the lock may be obtained (by calling
+** setSharedCacheTableLock()), or SQLITE_LOCKED if not.
+*/
+static int querySharedCacheTableLock(Btree *p, Pgno iTab, u8 eLock){
+  BtShared *pBt = p->pBt;
+  BtLock *pIter;
+
+  assert( sqlite3BtreeHoldsMutex(p) );
+  assert( eLock==READ_LOCK || eLock==WRITE_LOCK );
+  assert( p->db!=0 );
+  assert( !(p->db->flags&SQLITE_ReadUncommitted)||eLock==WRITE_LOCK||iTab==1 );
+  
+  /* If requesting a write-lock, then the Btree must have an open write
+  ** transaction on this file. And, obviously, for this to be so there 
+  ** must be an open write transaction on the file itself.
+  */
+  assert( eLock==READ_LOCK || (p==pBt->pWriter && p->inTrans==TRANS_WRITE) );
+  assert( eLock==READ_LOCK || pBt->inTransaction==TRANS_WRITE );
+  
+  /* This routine is a no-op if the shared-cache is not enabled */
+  if( !p->sharable ){
+    return SQLITE_OK;
+  }
+
+  /* If some other connection is holding an exclusive lock, the
+  ** requested lock may not be obtained.
+  */
+  if( pBt->pWriter!=p && (pBt->btsFlags & BTS_EXCLUSIVE)!=0 ){
+    sqlite3ConnectionBlocked(p->db, pBt->pWriter->db);
+    return SQLITE_LOCKED_SHAREDCACHE;
+  }
+
+  for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
+    /* The condition (pIter->eLock!=eLock) in the following if(...) 
+    ** statement is a simplification of:
+    **
+    **   (eLock==WRITE_LOCK || pIter->eLock==WRITE_LOCK)
+    **
+    ** since we know that if eLock==WRITE_LOCK, then no other connection
+    ** may hold a WRITE_LOCK on any table in this file (since there can
+    ** only be a single writer).
+    */
+    assert( pIter->eLock==READ_LOCK || pIter->eLock==WRITE_LOCK );
+    assert( eLock==READ_LOCK || pIter->pBtree==p || pIter->eLock==READ_LOCK);
+    if( pIter->pBtree!=p && pIter->iTable==iTab && pIter->eLock!=eLock ){
+      sqlite3ConnectionBlocked(p->db, pIter->pBtree->db);
+      if( eLock==WRITE_LOCK ){
+        assert( p==pBt->pWriter );
+        pBt->btsFlags |= BTS_PENDING;
+      }
+      return SQLITE_LOCKED_SHAREDCACHE;
+    }
+  }
+  return SQLITE_OK;
+}
+#endif /* !SQLITE_OMIT_SHARED_CACHE */
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+/*
+** Add a lock on the table with root-page iTable to the shared-btree used
+** by Btree handle p. Parameter eLock must be either READ_LOCK or 
+** WRITE_LOCK.
+**
+** This function assumes the following:
+**
+**   (a) The specified Btree object p is connected to a sharable
+**       database (one with the BtShared.sharable flag set), and
+**
+**   (b) No other Btree objects hold a lock that conflicts
+**       with the requested lock (i.e. querySharedCacheTableLock() has
+**       already been called and returned SQLITE_OK).
+**
+** SQLITE_OK is returned if the lock is added successfully. SQLITE_NOMEM 
+** is returned if a malloc attempt fails.
+*/
+static int setSharedCacheTableLock(Btree *p, Pgno iTable, u8 eLock){
+  BtShared *pBt = p->pBt;
+  BtLock *pLock = 0;
+  BtLock *pIter;
+
+  assert( sqlite3BtreeHoldsMutex(p) );
+  assert( eLock==READ_LOCK || eLock==WRITE_LOCK );
+  assert( p->db!=0 );
+
+  /* A connection with the read-uncommitted flag set will never try to
+  ** obtain a read-lock using this function. The only read-lock obtained
+  ** by a connection in read-uncommitted mode is on the sqlite_master 
+  ** table, and that lock is obtained in BtreeBeginTrans().  */
+  assert( 0==(p->db->flags&SQLITE_ReadUncommitted) || eLock==WRITE_LOCK );
+
+  /* This function should only be called on a sharable b-tree after it 
+  ** has been determined that no other b-tree holds a conflicting lock.  */
+  assert( p->sharable );
+  assert( SQLITE_OK==querySharedCacheTableLock(p, iTable, eLock) );
+
+  /* First search the list for an existing lock on this table. */
+  for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
+    if( pIter->iTable==iTable && pIter->pBtree==p ){
+      pLock = pIter;
+      break;
+    }
+  }
+
+  /* If the above search did not find a BtLock struct associating Btree p
+  ** with table iTable, allocate one and link it into the list.
+  */
+  if( !pLock ){
+    pLock = (BtLock *)sqlite3MallocZero(sizeof(BtLock));
+    if( !pLock ){
+      return SQLITE_NOMEM_BKPT;
+    }
+    pLock->iTable = iTable;
+    pLock->pBtree = p;
+    pLock->pNext = pBt->pLock;
+    pBt->pLock = pLock;
+  }
+
+  /* Set the BtLock.eLock variable to the maximum of the current lock
+  ** and the requested lock. This means if a write-lock was already held
+  ** and a read-lock requested, we don't incorrectly downgrade the lock.
+  */
+  assert( WRITE_LOCK>READ_LOCK );
+  if( eLock>pLock->eLock ){
+    pLock->eLock = eLock;
+  }
+
+  return SQLITE_OK;
+}
+#endif /* !SQLITE_OMIT_SHARED_CACHE */
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+/*
+** Release all the table locks (locks obtained via calls to
+** the setSharedCacheTableLock() procedure) held by Btree object p.
+**
+** This function assumes that Btree p has an open read or write 
+** transaction. If it does not, then the BTS_PENDING flag
+** may be incorrectly cleared.
+*/
+static void clearAllSharedCacheTableLocks(Btree *p){
+  BtShared *pBt = p->pBt;
+  BtLock **ppIter = &pBt->pLock;
+
+  assert( sqlite3BtreeHoldsMutex(p) );
+  assert( p->sharable || 0==*ppIter );
+  assert( p->inTrans>0 );
+
+  while( *ppIter ){
+    BtLock *pLock = *ppIter;
+    assert( (pBt->btsFlags & BTS_EXCLUSIVE)==0 || pBt->pWriter==pLock->pBtree );
+    assert( pLock->pBtree->inTrans>=pLock->eLock );
+    if( pLock->pBtree==p ){
+      *ppIter = pLock->pNext;
+      assert( pLock->iTable!=1 || pLock==&p->lock );
+      if( pLock->iTable!=1 ){
+        sqlite3_free(pLock);
+      }
+    }else{
+      ppIter = &pLock->pNext;
+    }
+  }
+
+  assert( (pBt->btsFlags & BTS_PENDING)==0 || pBt->pWriter );
+  if( pBt->pWriter==p ){
+    pBt->pWriter = 0;
+    pBt->btsFlags &= ~(BTS_EXCLUSIVE|BTS_PENDING);
+  }else if( pBt->nTransaction==2 ){
+    /* This function is called when Btree p is concluding its 
+    ** transaction. If there currently exists a writer, and p is not
+    ** that writer, then the number of locks held by connections other
+    ** than the writer must be about to drop to zero. In this case
+    ** set the BTS_PENDING flag to 0.
+    **
+    ** If there is not currently a writer, then BTS_PENDING must
+    ** be zero already. So this next line is harmless in that case.
+    */
+    pBt->btsFlags &= ~BTS_PENDING;
+  }
+}
+
+/*
+** This function changes all write-locks held by Btree p into read-locks.
+*/
+static void downgradeAllSharedCacheTableLocks(Btree *p){
+  BtShared *pBt = p->pBt;
+  if( pBt->pWriter==p ){
+    BtLock *pLock;
+    pBt->pWriter = 0;
+    pBt->btsFlags &= ~(BTS_EXCLUSIVE|BTS_PENDING);
+    for(pLock=pBt->pLock; pLock; pLock=pLock->pNext){
+      assert( pLock->eLock==READ_LOCK || pLock->pBtree==p );
+      pLock->eLock = READ_LOCK;
+    }
+  }
+}
+
+#endif /* SQLITE_OMIT_SHARED_CACHE */
+
+static void releasePage(MemPage *pPage);  /* Forward reference */
+
+/*
+***** This routine is used inside of assert() only ****
+**
+** Verify that the cursor holds the mutex on its BtShared
+*/
+#ifdef SQLITE_DEBUG
+static int cursorHoldsMutex(BtCursor *p){
+  return sqlite3_mutex_held(p->pBt->mutex);
+}
+
+/* Verify that the cursor and the BtShared agree about what is the current
+** database connetion. This is important in shared-cache mode. If the database 
+** connection pointers get out-of-sync, it is possible for routines like
+** btreeInitPage() to reference an stale connection pointer that references a
+** a connection that has already closed.  This routine is used inside assert()
+** statements only and for the purpose of double-checking that the btree code
+** does keep the database connection pointers up-to-date.
+*/
+static int cursorOwnsBtShared(BtCursor *p){
+  assert( cursorHoldsMutex(p) );
+  return (p->pBtree->db==p->pBt->db);
+}
+#endif
+
+/*
+** Invalidate the overflow cache of the cursor passed as the first argument.
+** on the shared btree structure pBt.
+*/
+#define invalidateOverflowCache(pCur) (pCur->curFlags &= ~BTCF_ValidOvfl)
+
+/*
+** Invalidate the overflow page-list cache for all cursors opened
+** on the shared btree structure pBt.
+*/
+static void invalidateAllOverflowCache(BtShared *pBt){
+  BtCursor *p;
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  for(p=pBt->pCursor; p; p=p->pNext){
+    invalidateOverflowCache(p);
+  }
+}
+
+#ifndef SQLITE_OMIT_INCRBLOB
+/*
+** This function is called before modifying the contents of a table
+** to invalidate any incrblob cursors that are open on the
+** row or one of the rows being modified.
+**
+** If argument isClearTable is true, then the entire contents of the
+** table is about to be deleted. In this case invalidate all incrblob
+** cursors open on any row within the table with root-page pgnoRoot.
+**
+** Otherwise, if argument isClearTable is false, then the row with
+** rowid iRow is being replaced or deleted. In this case invalidate
+** only those incrblob cursors open on that specific row.
+*/
+static void invalidateIncrblobCursors(
+  Btree *pBtree,          /* The database file to check */
+  i64 iRow,               /* The rowid that might be changing */
+  int isClearTable        /* True if all rows are being deleted */
+){
+  BtCursor *p;
+  if( pBtree->hasIncrblobCur==0 ) return;
+  assert( sqlite3BtreeHoldsMutex(pBtree) );
+  pBtree->hasIncrblobCur = 0;
+  for(p=pBtree->pBt->pCursor; p; p=p->pNext){
+    if( (p->curFlags & BTCF_Incrblob)!=0 ){
+      pBtree->hasIncrblobCur = 1;
+      if( isClearTable || p->info.nKey==iRow ){
+        p->eState = CURSOR_INVALID;
+      }
+    }
+  }
+}
+
+#else
+  /* Stub function when INCRBLOB is omitted */
+  #define invalidateIncrblobCursors(x,y,z)
+#endif /* SQLITE_OMIT_INCRBLOB */
+
+/*
+** Set bit pgno of the BtShared.pHasContent bitvec. This is called 
+** when a page that previously contained data becomes a free-list leaf 
+** page.
+**
+** The BtShared.pHasContent bitvec exists to work around an obscure
+** bug caused by the interaction of two useful IO optimizations surrounding
+** free-list leaf pages:
+**
+**   1) When all data is deleted from a page and the page becomes
+**      a free-list leaf page, the page is not written to the database
+**      (as free-list leaf pages contain no meaningful data). Sometimes
+**      such a page is not even journalled (as it will not be modified,
+**      why bother journalling it?).
+**
+**   2) When a free-list leaf page is reused, its content is not read
+**      from the database or written to the journal file (why should it
+**      be, if it is not at all meaningful?).
+**
+** By themselves, these optimizations work fine and provide a handy
+** performance boost to bulk delete or insert operations. However, if
+** a page is moved to the free-list and then reused within the same
+** transaction, a problem comes up. If the page is not journalled when
+** it is moved to the free-list and it is also not journalled when it
+** is extracted from the free-list and reused, then the original data
+** may be lost. In the event of a rollback, it may not be possible
+** to restore the database to its original configuration.
+**
+** The solution is the BtShared.pHasContent bitvec. Whenever a page is 
+** moved to become a free-list leaf page, the corresponding bit is
+** set in the bitvec. Whenever a leaf page is extracted from the free-list,
+** optimization 2 above is omitted if the corresponding bit is already
+** set in BtShared.pHasContent. The contents of the bitvec are cleared
+** at the end of every transaction.
+*/
+static int btreeSetHasContent(BtShared *pBt, Pgno pgno){
+  int rc = SQLITE_OK;
+  if( !pBt->pHasContent ){
+    assert( pgno<=pBt->nPage );
+    pBt->pHasContent = sqlite3BitvecCreate(pBt->nPage);
+    if( !pBt->pHasContent ){
+      rc = SQLITE_NOMEM_BKPT;
+    }
+  }
+  if( rc==SQLITE_OK && pgno<=sqlite3BitvecSize(pBt->pHasContent) ){
+    rc = sqlite3BitvecSet(pBt->pHasContent, pgno);
+  }
+  return rc;
+}
+
+/*
+** Query the BtShared.pHasContent vector.
+**
+** This function is called when a free-list leaf page is removed from the
+** free-list for reuse. It returns false if it is safe to retrieve the
+** page from the pager layer with the 'no-content' flag set. True otherwise.
+*/
+static int btreeGetHasContent(BtShared *pBt, Pgno pgno){
+  Bitvec *p = pBt->pHasContent;
+  return (p && (pgno>sqlite3BitvecSize(p) || sqlite3BitvecTest(p, pgno)));
+}
+
+/*
+** Clear (destroy) the BtShared.pHasContent bitvec. This should be
+** invoked at the conclusion of each write-transaction.
+*/
+static void btreeClearHasContent(BtShared *pBt){
+  sqlite3BitvecDestroy(pBt->pHasContent);
+  pBt->pHasContent = 0;
+}
+
+/*
+** Release all of the apPage[] pages for a cursor.
+*/
+static void btreeReleaseAllCursorPages(BtCursor *pCur){
+  int i;
+  for(i=0; i<=pCur->iPage; i++){
+    releasePage(pCur->apPage[i]);
+    pCur->apPage[i] = 0;
+  }
+  pCur->iPage = -1;
+}
+
+/*
+** The cursor passed as the only argument must point to a valid entry
+** when this function is called (i.e. have eState==CURSOR_VALID). This
+** function saves the current cursor key in variables pCur->nKey and
+** pCur->pKey. SQLITE_OK is returned if successful or an SQLite error 
+** code otherwise.
+**
+** If the cursor is open on an intkey table, then the integer key
+** (the rowid) is stored in pCur->nKey and pCur->pKey is left set to
+** NULL. If the cursor is open on a non-intkey table, then pCur->pKey is 
+** set to point to a malloced buffer pCur->nKey bytes in size containing 
+** the key.
+*/
+static int saveCursorKey(BtCursor *pCur){
+  int rc = SQLITE_OK;
+  assert( CURSOR_VALID==pCur->eState );
+  assert( 0==pCur->pKey );
+  assert( cursorHoldsMutex(pCur) );
+
+  if( pCur->curIntKey ){
+    /* Only the rowid is required for a table btree */
+    pCur->nKey = sqlite3BtreeIntegerKey(pCur);
+  }else{
+    /* For an index btree, save the complete key content */
+    void *pKey;
+    pCur->nKey = sqlite3BtreePayloadSize(pCur);
+    pKey = sqlite3Malloc( pCur->nKey );
+    if( pKey ){
+      rc = sqlite3BtreeKey(pCur, 0, (int)pCur->nKey, pKey);
+      if( rc==SQLITE_OK ){
+        pCur->pKey = pKey;
+      }else{
+        sqlite3_free(pKey);
+      }
+    }else{
+      rc = SQLITE_NOMEM_BKPT;
+    }
+  }
+  assert( !pCur->curIntKey || !pCur->pKey );
+  return rc;
+}
+
+/*
+** Save the current cursor position in the variables BtCursor.nKey 
+** and BtCursor.pKey. The cursor's state is set to CURSOR_REQUIRESEEK.
+**
+** The caller must ensure that the cursor is valid (has eState==CURSOR_VALID)
+** prior to calling this routine.  
+*/
+static int saveCursorPosition(BtCursor *pCur){
+  int rc;
+
+  assert( CURSOR_VALID==pCur->eState || CURSOR_SKIPNEXT==pCur->eState );
+  assert( 0==pCur->pKey );
+  assert( cursorHoldsMutex(pCur) );
+
+  if( pCur->eState==CURSOR_SKIPNEXT ){
+    pCur->eState = CURSOR_VALID;
+  }else{
+    pCur->skipNext = 0;
+  }
+
+  rc = saveCursorKey(pCur);
+  if( rc==SQLITE_OK ){
+    btreeReleaseAllCursorPages(pCur);
+    pCur->eState = CURSOR_REQUIRESEEK;
+  }
+
+  pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl|BTCF_AtLast);
+  return rc;
+}
+
+/* Forward reference */
+static int SQLITE_NOINLINE saveCursorsOnList(BtCursor*,Pgno,BtCursor*);
+
+/*
+** Save the positions of all cursors (except pExcept) that are open on
+** the table with root-page iRoot.  "Saving the cursor position" means that
+** the location in the btree is remembered in such a way that it can be
+** moved back to the same spot after the btree has been modified.  This
+** routine is called just before cursor pExcept is used to modify the
+** table, for example in BtreeDelete() or BtreeInsert().
+**
+** If there are two or more cursors on the same btree, then all such 
+** cursors should have their BTCF_Multiple flag set.  The btreeCursor()
+** routine enforces that rule.  This routine only needs to be called in
+** the uncommon case when pExpect has the BTCF_Multiple flag set.
+**
+** If pExpect!=NULL and if no other cursors are found on the same root-page,
+** then the BTCF_Multiple flag on pExpect is cleared, to avoid another
+** pointless call to this routine.
+**
+** Implementation note:  This routine merely checks to see if any cursors
+** need to be saved.  It calls out to saveCursorsOnList() in the (unusual)
+** event that cursors are in need to being saved.
+*/
+static int saveAllCursors(BtShared *pBt, Pgno iRoot, BtCursor *pExcept){
+  BtCursor *p;
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( pExcept==0 || pExcept->pBt==pBt );
+  for(p=pBt->pCursor; p; p=p->pNext){
+    if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) ) break;
+  }
+  if( p ) return saveCursorsOnList(p, iRoot, pExcept);
+  if( pExcept ) pExcept->curFlags &= ~BTCF_Multiple;
+  return SQLITE_OK;
+}
+
+/* This helper routine to saveAllCursors does the actual work of saving
+** the cursors if and when a cursor is found that actually requires saving.
+** The common case is that no cursors need to be saved, so this routine is
+** broken out from its caller to avoid unnecessary stack pointer movement.
+*/
+static int SQLITE_NOINLINE saveCursorsOnList(
+  BtCursor *p,         /* The first cursor that needs saving */
+  Pgno iRoot,          /* Only save cursor with this iRoot. Save all if zero */
+  BtCursor *pExcept    /* Do not save this cursor */
+){
+  do{
+    if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) ){
+      if( p->eState==CURSOR_VALID || p->eState==CURSOR_SKIPNEXT ){
+        int rc = saveCursorPosition(p);
+        if( SQLITE_OK!=rc ){
+          return rc;
+        }
+      }else{
+        testcase( p->iPage>0 );
+        btreeReleaseAllCursorPages(p);
+      }
+    }
+    p = p->pNext;
+  }while( p );
+  return SQLITE_OK;
+}
+
+/*
+** Clear the current cursor position.
+*/
+SQLITE_PRIVATE void sqlite3BtreeClearCursor(BtCursor *pCur){
+  assert( cursorHoldsMutex(pCur) );
+  sqlite3_free(pCur->pKey);
+  pCur->pKey = 0;
+  pCur->eState = CURSOR_INVALID;
+}
+
+/*
+** In this version of BtreeMoveto, pKey is a packed index record
+** such as is generated by the OP_MakeRecord opcode.  Unpack the
+** record and then call BtreeMovetoUnpacked() to do the work.
+*/
+static int btreeMoveto(
+  BtCursor *pCur,     /* Cursor open on the btree to be searched */
+  const void *pKey,   /* Packed key if the btree is an index */
+  i64 nKey,           /* Integer key for tables.  Size of pKey for indices */
+  int bias,           /* Bias search to the high end */
+  int *pRes           /* Write search results here */
+){
+  int rc;                    /* Status code */
+  UnpackedRecord *pIdxKey;   /* Unpacked index key */
+  char aSpace[384];          /* Temp space for pIdxKey - to avoid a malloc */
+  char *pFree = 0;
+
+  if( pKey ){
+    assert( nKey==(i64)(int)nKey );
+    pIdxKey = sqlite3VdbeAllocUnpackedRecord(
+        pCur->pKeyInfo, aSpace, sizeof(aSpace), &pFree
+    );
+    if( pIdxKey==0 ) return SQLITE_NOMEM_BKPT;
+    sqlite3VdbeRecordUnpack(pCur->pKeyInfo, (int)nKey, pKey, pIdxKey);
+    if( pIdxKey->nField==0 ){
+      sqlite3DbFree(pCur->pKeyInfo->db, pFree);
+      return SQLITE_CORRUPT_BKPT;
+    }
+  }else{
+    pIdxKey = 0;
+  }
+  rc = sqlite3BtreeMovetoUnpacked(pCur, pIdxKey, nKey, bias, pRes);
+  if( pFree ){
+    sqlite3DbFree(pCur->pKeyInfo->db, pFree);
+  }
+  return rc;
+}
+
+/*
+** Restore the cursor to the position it was in (or as close to as possible)
+** when saveCursorPosition() was called. Note that this call deletes the 
+** saved position info stored by saveCursorPosition(), so there can be
+** at most one effective restoreCursorPosition() call after each 
+** saveCursorPosition().
+*/
+static int btreeRestoreCursorPosition(BtCursor *pCur){
+  int rc;
+  int skipNext;
+  assert( cursorOwnsBtShared(pCur) );
+  assert( pCur->eState>=CURSOR_REQUIRESEEK );
+  if( pCur->eState==CURSOR_FAULT ){
+    return pCur->skipNext;
+  }
+  pCur->eState = CURSOR_INVALID;
+  rc = btreeMoveto(pCur, pCur->pKey, pCur->nKey, 0, &skipNext);
+  if( rc==SQLITE_OK ){
+    sqlite3_free(pCur->pKey);
+    pCur->pKey = 0;
+    assert( pCur->eState==CURSOR_VALID || pCur->eState==CURSOR_INVALID );
+    pCur->skipNext |= skipNext;
+    if( pCur->skipNext && pCur->eState==CURSOR_VALID ){
+      pCur->eState = CURSOR_SKIPNEXT;
+    }
+  }
+  return rc;
+}
+
+#define restoreCursorPosition(p) \
+  (p->eState>=CURSOR_REQUIRESEEK ? \
+         btreeRestoreCursorPosition(p) : \
+         SQLITE_OK)
+
+/*
+** Determine whether or not a cursor has moved from the position where
+** it was last placed, or has been invalidated for any other reason.
+** Cursors can move when the row they are pointing at is deleted out
+** from under them, for example.  Cursor might also move if a btree
+** is rebalanced.
+**
+** Calling this routine with a NULL cursor pointer returns false.
+**
+** Use the separate sqlite3BtreeCursorRestore() routine to restore a cursor
+** back to where it ought to be if this routine returns true.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCursorHasMoved(BtCursor *pCur){
+  return pCur->eState!=CURSOR_VALID;
+}
+
+/*
+** This routine restores a cursor back to its original position after it
+** has been moved by some outside activity (such as a btree rebalance or
+** a row having been deleted out from under the cursor).  
+**
+** On success, the *pDifferentRow parameter is false if the cursor is left
+** pointing at exactly the same row.  *pDifferntRow is the row the cursor
+** was pointing to has been deleted, forcing the cursor to point to some
+** nearby row.
+**
+** This routine should only be called for a cursor that just returned
+** TRUE from sqlite3BtreeCursorHasMoved().
+*/
+SQLITE_PRIVATE int sqlite3BtreeCursorRestore(BtCursor *pCur, int *pDifferentRow){
+  int rc;
+
+  assert( pCur!=0 );
+  assert( pCur->eState!=CURSOR_VALID );
+  rc = restoreCursorPosition(pCur);
+  if( rc ){
+    *pDifferentRow = 1;
+    return rc;
+  }
+  if( pCur->eState!=CURSOR_VALID ){
+    *pDifferentRow = 1;
+  }else{
+    assert( pCur->skipNext==0 );
+    *pDifferentRow = 0;
+  }
+  return SQLITE_OK;
+}
+
+#ifdef SQLITE_ENABLE_CURSOR_HINTS
+/*
+** Provide hints to the cursor.  The particular hint given (and the type
+** and number of the varargs parameters) is determined by the eHintType
+** parameter.  See the definitions of the BTREE_HINT_* macros for details.
+*/
+SQLITE_PRIVATE void sqlite3BtreeCursorHint(BtCursor *pCur, int eHintType, ...){
+  /* Used only by system that substitute their own storage engine */
+}
+#endif
+
+/*
+** Provide flag hints to the cursor.
+*/
+SQLITE_PRIVATE void sqlite3BtreeCursorHintFlags(BtCursor *pCur, unsigned x){
+  assert( x==BTREE_SEEK_EQ || x==BTREE_BULKLOAD || x==0 );
+  pCur->hints = x;
+}
+
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+/*
+** Given a page number of a regular database page, return the page
+** number for the pointer-map page that contains the entry for the
+** input page number.
+**
+** Return 0 (not a valid page) for pgno==1 since there is
+** no pointer map associated with page 1.  The integrity_check logic
+** requires that ptrmapPageno(*,1)!=1.
+*/
+static Pgno ptrmapPageno(BtShared *pBt, Pgno pgno){
+  int nPagesPerMapPage;
+  Pgno iPtrMap, ret;
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  if( pgno<2 ) return 0;
+  nPagesPerMapPage = (pBt->usableSize/5)+1;
+  iPtrMap = (pgno-2)/nPagesPerMapPage;
+  ret = (iPtrMap*nPagesPerMapPage) + 2; 
+  if( ret==PENDING_BYTE_PAGE(pBt) ){
+    ret++;
+  }
+  return ret;
+}
+
+/*
+** Write an entry into the pointer map.
+**
+** This routine updates the pointer map entry for page number 'key'
+** so that it maps to type 'eType' and parent page number 'pgno'.
+**
+** If *pRC is initially non-zero (non-SQLITE_OK) then this routine is
+** a no-op.  If an error occurs, the appropriate error code is written
+** into *pRC.
+*/
+static void ptrmapPut(BtShared *pBt, Pgno key, u8 eType, Pgno parent, int *pRC){
+  DbPage *pDbPage;  /* The pointer map page */
+  u8 *pPtrmap;      /* The pointer map data */
+  Pgno iPtrmap;     /* The pointer map page number */
+  int offset;       /* Offset in pointer map page */
+  int rc;           /* Return code from subfunctions */
+
+  if( *pRC ) return;
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  /* The master-journal page number must never be used as a pointer map page */
+  assert( 0==PTRMAP_ISPAGE(pBt, PENDING_BYTE_PAGE(pBt)) );
+
+  assert( pBt->autoVacuum );
+  if( key==0 ){
+    *pRC = SQLITE_CORRUPT_BKPT;
+    return;
+  }
+  iPtrmap = PTRMAP_PAGENO(pBt, key);
+  rc = sqlite3PagerGet(pBt->pPager, iPtrmap, &pDbPage, 0);
+  if( rc!=SQLITE_OK ){
+    *pRC = rc;
+    return;
+  }
+  offset = PTRMAP_PTROFFSET(iPtrmap, key);
+  if( offset<0 ){
+    *pRC = SQLITE_CORRUPT_BKPT;
+    goto ptrmap_exit;
+  }
+  assert( offset <= (int)pBt->usableSize-5 );
+  pPtrmap = (u8 *)sqlite3PagerGetData(pDbPage);
+
+  if( eType!=pPtrmap[offset] || get4byte(&pPtrmap[offset+1])!=parent ){
+    TRACE(("PTRMAP_UPDATE: %d->(%d,%d)\n", key, eType, parent));
+    *pRC= rc = sqlite3PagerWrite(pDbPage);
+    if( rc==SQLITE_OK ){
+      pPtrmap[offset] = eType;
+      put4byte(&pPtrmap[offset+1], parent);
+    }
+  }
+
+ptrmap_exit:
+  sqlite3PagerUnref(pDbPage);
+}
+
+/*
+** Read an entry from the pointer map.
+**
+** This routine retrieves the pointer map entry for page 'key', writing
+** the type and parent page number to *pEType and *pPgno respectively.
+** An error code is returned if something goes wrong, otherwise SQLITE_OK.
+*/
+static int ptrmapGet(BtShared *pBt, Pgno key, u8 *pEType, Pgno *pPgno){
+  DbPage *pDbPage;   /* The pointer map page */
+  int iPtrmap;       /* Pointer map page index */
+  u8 *pPtrmap;       /* Pointer map page data */
+  int offset;        /* Offset of entry in pointer map */
+  int rc;
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+
+  iPtrmap = PTRMAP_PAGENO(pBt, key);
+  rc = sqlite3PagerGet(pBt->pPager, iPtrmap, &pDbPage, 0);
+  if( rc!=0 ){
+    return rc;
+  }
+  pPtrmap = (u8 *)sqlite3PagerGetData(pDbPage);
+
+  offset = PTRMAP_PTROFFSET(iPtrmap, key);
+  if( offset<0 ){
+    sqlite3PagerUnref(pDbPage);
+    return SQLITE_CORRUPT_BKPT;
+  }
+  assert( offset <= (int)pBt->usableSize-5 );
+  assert( pEType!=0 );
+  *pEType = pPtrmap[offset];
+  if( pPgno ) *pPgno = get4byte(&pPtrmap[offset+1]);
+
+  sqlite3PagerUnref(pDbPage);
+  if( *pEType<1 || *pEType>5 ) return SQLITE_CORRUPT_BKPT;
+  return SQLITE_OK;
+}
+
+#else /* if defined SQLITE_OMIT_AUTOVACUUM */
+  #define ptrmapPut(w,x,y,z,rc)
+  #define ptrmapGet(w,x,y,z) SQLITE_OK
+  #define ptrmapPutOvflPtr(x, y, rc)
+#endif
+
+/*
+** Given a btree page and a cell index (0 means the first cell on
+** the page, 1 means the second cell, and so forth) return a pointer
+** to the cell content.
+**
+** findCellPastPtr() does the same except it skips past the initial
+** 4-byte child pointer found on interior pages, if there is one.
+**
+** This routine works only for pages that do not contain overflow cells.
+*/
+#define findCell(P,I) \
+  ((P)->aData + ((P)->maskPage & get2byteAligned(&(P)->aCellIdx[2*(I)])))
+#define findCellPastPtr(P,I) \
+  ((P)->aDataOfst + ((P)->maskPage & get2byteAligned(&(P)->aCellIdx[2*(I)])))
+
+
+/*
+** This is common tail processing for btreeParseCellPtr() and
+** btreeParseCellPtrIndex() for the case when the cell does not fit entirely
+** on a single B-tree page.  Make necessary adjustments to the CellInfo
+** structure.
+*/
+static SQLITE_NOINLINE void btreeParseCellAdjustSizeForOverflow(
+  MemPage *pPage,         /* Page containing the cell */
+  u8 *pCell,              /* Pointer to the cell text. */
+  CellInfo *pInfo         /* Fill in this structure */
+){
+  /* If the payload will not fit completely on the local page, we have
+  ** to decide how much to store locally and how much to spill onto
+  ** overflow pages.  The strategy is to minimize the amount of unused
+  ** space on overflow pages while keeping the amount of local storage
+  ** in between minLocal and maxLocal.
+  **
+  ** Warning:  changing the way overflow payload is distributed in any
+  ** way will result in an incompatible file format.
+  */
+  int minLocal;  /* Minimum amount of payload held locally */
+  int maxLocal;  /* Maximum amount of payload held locally */
+  int surplus;   /* Overflow payload available for local storage */
+
+  minLocal = pPage->minLocal;
+  maxLocal = pPage->maxLocal;
+  surplus = minLocal + (pInfo->nPayload - minLocal)%(pPage->pBt->usableSize-4);
+  testcase( surplus==maxLocal );
+  testcase( surplus==maxLocal+1 );
+  if( surplus <= maxLocal ){
+    pInfo->nLocal = (u16)surplus;
+  }else{
+    pInfo->nLocal = (u16)minLocal;
+  }
+  pInfo->nSize = (u16)(&pInfo->pPayload[pInfo->nLocal] - pCell) + 4;
+}
+
+/*
+** The following routines are implementations of the MemPage.xParseCell()
+** method.
+**
+** Parse a cell content block and fill in the CellInfo structure.
+**
+** btreeParseCellPtr()        =>   table btree leaf nodes
+** btreeParseCellNoPayload()  =>   table btree internal nodes
+** btreeParseCellPtrIndex()   =>   index btree nodes
+**
+** There is also a wrapper function btreeParseCell() that works for
+** all MemPage types and that references the cell by index rather than
+** by pointer.
+*/
+static void btreeParseCellPtrNoPayload(
+  MemPage *pPage,         /* Page containing the cell */
+  u8 *pCell,              /* Pointer to the cell text. */
+  CellInfo *pInfo         /* Fill in this structure */
+){
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  assert( pPage->leaf==0 );
+  assert( pPage->childPtrSize==4 );
+#ifndef SQLITE_DEBUG
+  UNUSED_PARAMETER(pPage);
+#endif
+  pInfo->nSize = 4 + getVarint(&pCell[4], (u64*)&pInfo->nKey);
+  pInfo->nPayload = 0;
+  pInfo->nLocal = 0;
+  pInfo->pPayload = 0;
+  return;
+}
+static void btreeParseCellPtr(
+  MemPage *pPage,         /* Page containing the cell */
+  u8 *pCell,              /* Pointer to the cell text. */
+  CellInfo *pInfo         /* Fill in this structure */
+){
+  u8 *pIter;              /* For scanning through pCell */
+  u32 nPayload;           /* Number of bytes of cell payload */
+  u64 iKey;               /* Extracted Key value */
+
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  assert( pPage->leaf==0 || pPage->leaf==1 );
+  assert( pPage->intKeyLeaf );
+  assert( pPage->childPtrSize==0 );
+  pIter = pCell;
+
+  /* The next block of code is equivalent to:
+  **
+  **     pIter += getVarint32(pIter, nPayload);
+  **
+  ** The code is inlined to avoid a function call.
+  */
+  nPayload = *pIter;
+  if( nPayload>=0x80 ){
+    u8 *pEnd = &pIter[8];
+    nPayload &= 0x7f;
+    do{
+      nPayload = (nPayload<<7) | (*++pIter & 0x7f);
+    }while( (*pIter)>=0x80 && pIter<pEnd );
+  }
+  pIter++;
+
+  /* The next block of code is equivalent to:
+  **
+  **     pIter += getVarint(pIter, (u64*)&pInfo->nKey);
+  **
+  ** The code is inlined to avoid a function call.
+  */
+  iKey = *pIter;
+  if( iKey>=0x80 ){
+    u8 *pEnd = &pIter[7];
+    iKey &= 0x7f;
+    while(1){
+      iKey = (iKey<<7) | (*++pIter & 0x7f);
+      if( (*pIter)<0x80 ) break;
+      if( pIter>=pEnd ){
+        iKey = (iKey<<8) | *++pIter;
+        break;
+      }
+    }
+  }
+  pIter++;
+
+  pInfo->nKey = *(i64*)&iKey;
+  pInfo->nPayload = nPayload;
+  pInfo->pPayload = pIter;
+  testcase( nPayload==pPage->maxLocal );
+  testcase( nPayload==pPage->maxLocal+1 );
+  if( nPayload<=pPage->maxLocal ){
+    /* This is the (easy) common case where the entire payload fits
+    ** on the local page.  No overflow is required.
+    */
+    pInfo->nSize = nPayload + (u16)(pIter - pCell);
+    if( pInfo->nSize<4 ) pInfo->nSize = 4;
+    pInfo->nLocal = (u16)nPayload;
+  }else{
+    btreeParseCellAdjustSizeForOverflow(pPage, pCell, pInfo);
+  }
+}
+static void btreeParseCellPtrIndex(
+  MemPage *pPage,         /* Page containing the cell */
+  u8 *pCell,              /* Pointer to the cell text. */
+  CellInfo *pInfo         /* Fill in this structure */
+){
+  u8 *pIter;              /* For scanning through pCell */
+  u32 nPayload;           /* Number of bytes of cell payload */
+
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  assert( pPage->leaf==0 || pPage->leaf==1 );
+  assert( pPage->intKeyLeaf==0 );
+  pIter = pCell + pPage->childPtrSize;
+  nPayload = *pIter;
+  if( nPayload>=0x80 ){
+    u8 *pEnd = &pIter[8];
+    nPayload &= 0x7f;
+    do{
+      nPayload = (nPayload<<7) | (*++pIter & 0x7f);
+    }while( *(pIter)>=0x80 && pIter<pEnd );
+  }
+  pIter++;
+  pInfo->nKey = nPayload;
+  pInfo->nPayload = nPayload;
+  pInfo->pPayload = pIter;
+  testcase( nPayload==pPage->maxLocal );
+  testcase( nPayload==pPage->maxLocal+1 );
+  if( nPayload<=pPage->maxLocal ){
+    /* This is the (easy) common case where the entire payload fits
+    ** on the local page.  No overflow is required.
+    */
+    pInfo->nSize = nPayload + (u16)(pIter - pCell);
+    if( pInfo->nSize<4 ) pInfo->nSize = 4;
+    pInfo->nLocal = (u16)nPayload;
+  }else{
+    btreeParseCellAdjustSizeForOverflow(pPage, pCell, pInfo);
+  }
+}
+static void btreeParseCell(
+  MemPage *pPage,         /* Page containing the cell */
+  int iCell,              /* The cell index.  First cell is 0 */
+  CellInfo *pInfo         /* Fill in this structure */
+){
+  pPage->xParseCell(pPage, findCell(pPage, iCell), pInfo);
+}
+
+/*
+** The following routines are implementations of the MemPage.xCellSize
+** method.
+**
+** Compute the total number of bytes that a Cell needs in the cell
+** data area of the btree-page.  The return number includes the cell
+** data header and the local payload, but not any overflow page or
+** the space used by the cell pointer.
+**
+** cellSizePtrNoPayload()    =>   table internal nodes
+** cellSizePtr()             =>   all index nodes & table leaf nodes
+*/
+static u16 cellSizePtr(MemPage *pPage, u8 *pCell){
+  u8 *pIter = pCell + pPage->childPtrSize; /* For looping over bytes of pCell */
+  u8 *pEnd;                                /* End mark for a varint */
+  u32 nSize;                               /* Size value to return */
+
+#ifdef SQLITE_DEBUG
+  /* The value returned by this function should always be the same as
+  ** the (CellInfo.nSize) value found by doing a full parse of the
+  ** cell. If SQLITE_DEBUG is defined, an assert() at the bottom of
+  ** this function verifies that this invariant is not violated. */
+  CellInfo debuginfo;
+  pPage->xParseCell(pPage, pCell, &debuginfo);
+#endif
+
+  nSize = *pIter;
+  if( nSize>=0x80 ){
+    pEnd = &pIter[8];
+    nSize &= 0x7f;
+    do{
+      nSize = (nSize<<7) | (*++pIter & 0x7f);
+    }while( *(pIter)>=0x80 && pIter<pEnd );
+  }
+  pIter++;
+  if( pPage->intKey ){
+    /* pIter now points at the 64-bit integer key value, a variable length 
+    ** integer. The following block moves pIter to point at the first byte
+    ** past the end of the key value. */
+    pEnd = &pIter[9];
+    while( (*pIter++)&0x80 && pIter<pEnd );
+  }
+  testcase( nSize==pPage->maxLocal );
+  testcase( nSize==pPage->maxLocal+1 );
+  if( nSize<=pPage->maxLocal ){
+    nSize += (u32)(pIter - pCell);
+    if( nSize<4 ) nSize = 4;
+  }else{
+    int minLocal = pPage->minLocal;
+    nSize = minLocal + (nSize - minLocal) % (pPage->pBt->usableSize - 4);
+    testcase( nSize==pPage->maxLocal );
+    testcase( nSize==pPage->maxLocal+1 );
+    if( nSize>pPage->maxLocal ){
+      nSize = minLocal;
+    }
+    nSize += 4 + (u16)(pIter - pCell);
+  }
+  assert( nSize==debuginfo.nSize || CORRUPT_DB );
+  return (u16)nSize;
+}
+static u16 cellSizePtrNoPayload(MemPage *pPage, u8 *pCell){
+  u8 *pIter = pCell + 4; /* For looping over bytes of pCell */
+  u8 *pEnd;              /* End mark for a varint */
+
+#ifdef SQLITE_DEBUG
+  /* The value returned by this function should always be the same as
+  ** the (CellInfo.nSize) value found by doing a full parse of the
+  ** cell. If SQLITE_DEBUG is defined, an assert() at the bottom of
+  ** this function verifies that this invariant is not violated. */
+  CellInfo debuginfo;
+  pPage->xParseCell(pPage, pCell, &debuginfo);
+#else
+  UNUSED_PARAMETER(pPage);
+#endif
+
+  assert( pPage->childPtrSize==4 );
+  pEnd = pIter + 9;
+  while( (*pIter++)&0x80 && pIter<pEnd );
+  assert( debuginfo.nSize==(u16)(pIter - pCell) || CORRUPT_DB );
+  return (u16)(pIter - pCell);
+}
+
+
+#ifdef SQLITE_DEBUG
+/* This variation on cellSizePtr() is used inside of assert() statements
+** only. */
+static u16 cellSize(MemPage *pPage, int iCell){
+  return pPage->xCellSize(pPage, findCell(pPage, iCell));
+}
+#endif
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+/*
+** If the cell pCell, part of page pPage contains a pointer
+** to an overflow page, insert an entry into the pointer-map
+** for the overflow page.
+*/
+static void ptrmapPutOvflPtr(MemPage *pPage, u8 *pCell, int *pRC){
+  CellInfo info;
+  if( *pRC ) return;
+  assert( pCell!=0 );
+  pPage->xParseCell(pPage, pCell, &info);
+  if( info.nLocal<info.nPayload ){
+    Pgno ovfl = get4byte(&pCell[info.nSize-4]);
+    ptrmapPut(pPage->pBt, ovfl, PTRMAP_OVERFLOW1, pPage->pgno, pRC);
+  }
+}
+#endif
+
+
+/*
+** Defragment the page given.  All Cells are moved to the
+** end of the page and all free space is collected into one
+** big FreeBlk that occurs in between the header and cell
+** pointer array and the cell content area.
+**
+** EVIDENCE-OF: R-44582-60138 SQLite may from time to time reorganize a
+** b-tree page so that there are no freeblocks or fragment bytes, all
+** unused bytes are contained in the unallocated space region, and all
+** cells are packed tightly at the end of the page.
+*/
+static int defragmentPage(MemPage *pPage){
+  int i;                     /* Loop counter */
+  int pc;                    /* Address of the i-th cell */
+  int hdr;                   /* Offset to the page header */
+  int size;                  /* Size of a cell */
+  int usableSize;            /* Number of usable bytes on a page */
+  int cellOffset;            /* Offset to the cell pointer array */
+  int cbrk;                  /* Offset to the cell content area */
+  int nCell;                 /* Number of cells on the page */
+  unsigned char *data;       /* The page data */
+  unsigned char *temp;       /* Temp area for cell content */
+  unsigned char *src;        /* Source of content */
+  int iCellFirst;            /* First allowable cell index */
+  int iCellLast;             /* Last possible cell index */
+
+
+  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+  assert( pPage->pBt!=0 );
+  assert( pPage->pBt->usableSize <= SQLITE_MAX_PAGE_SIZE );
+  assert( pPage->nOverflow==0 );
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  temp = 0;
+  src = data = pPage->aData;
+  hdr = pPage->hdrOffset;
+  cellOffset = pPage->cellOffset;
+  nCell = pPage->nCell;
+  assert( nCell==get2byte(&data[hdr+3]) );
+  usableSize = pPage->pBt->usableSize;
+  cbrk = usableSize;
+  iCellFirst = cellOffset + 2*nCell;
+  iCellLast = usableSize - 4;
+  for(i=0; i<nCell; i++){
+    u8 *pAddr;     /* The i-th cell pointer */
+    pAddr = &data[cellOffset + i*2];
+    pc = get2byte(pAddr);
+    testcase( pc==iCellFirst );
+    testcase( pc==iCellLast );
+    /* These conditions have already been verified in btreeInitPage()
+    ** if PRAGMA cell_size_check=ON.
+    */
+    if( pc<iCellFirst || pc>iCellLast ){
+      return SQLITE_CORRUPT_BKPT;
+    }
+    assert( pc>=iCellFirst && pc<=iCellLast );
+    size = pPage->xCellSize(pPage, &src[pc]);
+    cbrk -= size;
+    if( cbrk<iCellFirst || pc+size>usableSize ){
+      return SQLITE_CORRUPT_BKPT;
+    }
+    assert( cbrk+size<=usableSize && cbrk>=iCellFirst );
+    testcase( cbrk+size==usableSize );
+    testcase( pc+size==usableSize );
+    put2byte(pAddr, cbrk);
+    if( temp==0 ){
+      int x;
+      if( cbrk==pc ) continue;
+      temp = sqlite3PagerTempSpace(pPage->pBt->pPager);
+      x = get2byte(&data[hdr+5]);
+      memcpy(&temp[x], &data[x], (cbrk+size) - x);
+      src = temp;
+    }
+    memcpy(&data[cbrk], &src[pc], size);
+  }
+  assert( cbrk>=iCellFirst );
+  put2byte(&data[hdr+5], cbrk);
+  data[hdr+1] = 0;
+  data[hdr+2] = 0;
+  data[hdr+7] = 0;
+  memset(&data[iCellFirst], 0, cbrk-iCellFirst);
+  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+  if( cbrk-iCellFirst!=pPage->nFree ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Search the free-list on page pPg for space to store a cell nByte bytes in
+** size. If one can be found, return a pointer to the space and remove it
+** from the free-list.
+**
+** If no suitable space can be found on the free-list, return NULL.
+**
+** This function may detect corruption within pPg.  If corruption is
+** detected then *pRc is set to SQLITE_CORRUPT and NULL is returned.
+**
+** Slots on the free list that are between 1 and 3 bytes larger than nByte
+** will be ignored if adding the extra space to the fragmentation count
+** causes the fragmentation count to exceed 60.
+*/
+static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc){
+  const int hdr = pPg->hdrOffset;
+  u8 * const aData = pPg->aData;
+  int iAddr = hdr + 1;
+  int pc = get2byte(&aData[iAddr]);
+  int x;
+  int usableSize = pPg->pBt->usableSize;
+
+  assert( pc>0 );
+  do{
+    int size;            /* Size of the free slot */
+    /* EVIDENCE-OF: R-06866-39125 Freeblocks are always connected in order of
+    ** increasing offset. */
+    if( pc>usableSize-4 || pc<iAddr+4 ){
+      *pRc = SQLITE_CORRUPT_BKPT;
+      return 0;
+    }
+    /* EVIDENCE-OF: R-22710-53328 The third and fourth bytes of each
+    ** freeblock form a big-endian integer which is the size of the freeblock
+    ** in bytes, including the 4-byte header. */
+    size = get2byte(&aData[pc+2]);
+    if( (x = size - nByte)>=0 ){
+      testcase( x==4 );
+      testcase( x==3 );
+      if( pc < pPg->cellOffset+2*pPg->nCell || size+pc > usableSize ){
+        *pRc = SQLITE_CORRUPT_BKPT;
+        return 0;
+      }else if( x<4 ){
+        /* EVIDENCE-OF: R-11498-58022 In a well-formed b-tree page, the total
+        ** number of bytes in fragments may not exceed 60. */
+        if( aData[hdr+7]>57 ) return 0;
+
+        /* Remove the slot from the free-list. Update the number of
+        ** fragmented bytes within the page. */
+        memcpy(&aData[iAddr], &aData[pc], 2);
+        aData[hdr+7] += (u8)x;
+      }else{
+        /* The slot remains on the free-list. Reduce its size to account
+         ** for the portion used by the new allocation. */
+        put2byte(&aData[pc+2], x);
+      }
+      return &aData[pc + x];
+    }
+    iAddr = pc;
+    pc = get2byte(&aData[pc]);
+  }while( pc );
+
+  return 0;
+}
+
+/*
+** Allocate nByte bytes of space from within the B-Tree page passed
+** as the first argument. Write into *pIdx the index into pPage->aData[]
+** of the first byte of allocated space. Return either SQLITE_OK or
+** an error code (usually SQLITE_CORRUPT).
+**
+** The caller guarantees that there is sufficient space to make the
+** allocation.  This routine might need to defragment in order to bring
+** all the space together, however.  This routine will avoid using
+** the first two bytes past the cell pointer area since presumably this
+** allocation is being made in order to insert a new cell, so we will
+** also end up needing a new cell pointer.
+*/
+static int allocateSpace(MemPage *pPage, int nByte, int *pIdx){
+  const int hdr = pPage->hdrOffset;    /* Local cache of pPage->hdrOffset */
+  u8 * const data = pPage->aData;      /* Local cache of pPage->aData */
+  int top;                             /* First byte of cell content area */
+  int rc = SQLITE_OK;                  /* Integer return code */
+  int gap;        /* First byte of gap between cell pointers and cell content */
+  
+  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+  assert( pPage->pBt );
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  assert( nByte>=0 );  /* Minimum cell size is 4 */
+  assert( pPage->nFree>=nByte );
+  assert( pPage->nOverflow==0 );
+  assert( nByte < (int)(pPage->pBt->usableSize-8) );
+
+  assert( pPage->cellOffset == hdr + 12 - 4*pPage->leaf );
+  gap = pPage->cellOffset + 2*pPage->nCell;
+  assert( gap<=65536 );
+  /* EVIDENCE-OF: R-29356-02391 If the database uses a 65536-byte page size
+  ** and the reserved space is zero (the usual value for reserved space)
+  ** then the cell content offset of an empty page wants to be 65536.
+  ** However, that integer is too large to be stored in a 2-byte unsigned
+  ** integer, so a value of 0 is used in its place. */
+  top = get2byte(&data[hdr+5]);
+  assert( top<=(int)pPage->pBt->usableSize ); /* Prevent by getAndInitPage() */
+  if( gap>top ){
+    if( top==0 && pPage->pBt->usableSize==65536 ){
+      top = 65536;
+    }else{
+      return SQLITE_CORRUPT_BKPT;
+    }
+  }
+
+  /* If there is enough space between gap and top for one more cell pointer
+  ** array entry offset, and if the freelist is not empty, then search the
+  ** freelist looking for a free slot big enough to satisfy the request.
+  */
+  testcase( gap+2==top );
+  testcase( gap+1==top );
+  testcase( gap==top );
+  if( (data[hdr+2] || data[hdr+1]) && gap+2<=top ){
+    u8 *pSpace = pageFindSlot(pPage, nByte, &rc);
+    if( pSpace ){
+      assert( pSpace>=data && (pSpace - data)<65536 );
+      *pIdx = (int)(pSpace - data);
+      return SQLITE_OK;
+    }else if( rc ){
+      return rc;
+    }
+  }
+
+  /* The request could not be fulfilled using a freelist slot.  Check
+  ** to see if defragmentation is necessary.
+  */
+  testcase( gap+2+nByte==top );
+  if( gap+2+nByte>top ){
+    assert( pPage->nCell>0 || CORRUPT_DB );
+    rc = defragmentPage(pPage);
+    if( rc ) return rc;
+    top = get2byteNotZero(&data[hdr+5]);
+    assert( gap+nByte<=top );
+  }
+
+
+  /* Allocate memory from the gap in between the cell pointer array
+  ** and the cell content area.  The btreeInitPage() call has already
+  ** validated the freelist.  Given that the freelist is valid, there
+  ** is no way that the allocation can extend off the end of the page.
+  ** The assert() below verifies the previous sentence.
+  */
+  top -= nByte;
+  put2byte(&data[hdr+5], top);
+  assert( top+nByte <= (int)pPage->pBt->usableSize );
+  *pIdx = top;
+  return SQLITE_OK;
+}
+
+/*
+** Return a section of the pPage->aData to the freelist.
+** The first byte of the new free block is pPage->aData[iStart]
+** and the size of the block is iSize bytes.
+**
+** Adjacent freeblocks are coalesced.
+**
+** Note that even though the freeblock list was checked by btreeInitPage(),
+** that routine will not detect overlap between cells or freeblocks.  Nor
+** does it detect cells or freeblocks that encrouch into the reserved bytes
+** at the end of the page.  So do additional corruption checks inside this
+** routine and return SQLITE_CORRUPT if any problems are found.
+*/
+static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
+  u16 iPtr;                             /* Address of ptr to next freeblock */
+  u16 iFreeBlk;                         /* Address of the next freeblock */
+  u8 hdr;                               /* Page header size.  0 or 100 */
+  u8 nFrag = 0;                         /* Reduction in fragmentation */
+  u16 iOrigSize = iSize;                /* Original value of iSize */
+  u32 iLast = pPage->pBt->usableSize-4; /* Largest possible freeblock offset */
+  u32 iEnd = iStart + iSize;            /* First byte past the iStart buffer */
+  unsigned char *data = pPage->aData;   /* Page content */
+
+  assert( pPage->pBt!=0 );
+  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+  assert( CORRUPT_DB || iStart>=pPage->hdrOffset+6+pPage->childPtrSize );
+  assert( CORRUPT_DB || iEnd <= pPage->pBt->usableSize );
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  assert( iSize>=4 );   /* Minimum cell size is 4 */
+  assert( iStart<=iLast );
+
+  /* Overwrite deleted information with zeros when the secure_delete
+  ** option is enabled */
+  if( pPage->pBt->btsFlags & BTS_SECURE_DELETE ){
+    memset(&data[iStart], 0, iSize);
+  }
+
+  /* The list of freeblocks must be in ascending order.  Find the 
+  ** spot on the list where iStart should be inserted.
+  */
+  hdr = pPage->hdrOffset;
+  iPtr = hdr + 1;
+  if( data[iPtr+1]==0 && data[iPtr]==0 ){
+    iFreeBlk = 0;  /* Shortcut for the case when the freelist is empty */
+  }else{
+    while( (iFreeBlk = get2byte(&data[iPtr]))<iStart ){
+      if( iFreeBlk<iPtr+4 ){
+        if( iFreeBlk==0 ) break;
+        return SQLITE_CORRUPT_BKPT;
+      }
+      iPtr = iFreeBlk;
+    }
+    if( iFreeBlk>iLast ) return SQLITE_CORRUPT_BKPT;
+    assert( iFreeBlk>iPtr || iFreeBlk==0 );
+  
+    /* At this point:
+    **    iFreeBlk:   First freeblock after iStart, or zero if none
+    **    iPtr:       The address of a pointer to iFreeBlk
+    **
+    ** Check to see if iFreeBlk should be coalesced onto the end of iStart.
+    */
+    if( iFreeBlk && iEnd+3>=iFreeBlk ){
+      nFrag = iFreeBlk - iEnd;
+      if( iEnd>iFreeBlk ) return SQLITE_CORRUPT_BKPT;
+      iEnd = iFreeBlk + get2byte(&data[iFreeBlk+2]);
+      if( iEnd > pPage->pBt->usableSize ) return SQLITE_CORRUPT_BKPT;
+      iSize = iEnd - iStart;
+      iFreeBlk = get2byte(&data[iFreeBlk]);
+    }
+  
+    /* If iPtr is another freeblock (that is, if iPtr is not the freelist
+    ** pointer in the page header) then check to see if iStart should be
+    ** coalesced onto the end of iPtr.
+    */
+    if( iPtr>hdr+1 ){
+      int iPtrEnd = iPtr + get2byte(&data[iPtr+2]);
+      if( iPtrEnd+3>=iStart ){
+        if( iPtrEnd>iStart ) return SQLITE_CORRUPT_BKPT;
+        nFrag += iStart - iPtrEnd;
+        iSize = iEnd - iPtr;
+        iStart = iPtr;
+      }
+    }
+    if( nFrag>data[hdr+7] ) return SQLITE_CORRUPT_BKPT;
+    data[hdr+7] -= nFrag;
+  }
+  if( iStart==get2byte(&data[hdr+5]) ){
+    /* The new freeblock is at the beginning of the cell content area,
+    ** so just extend the cell content area rather than create another
+    ** freelist entry */
+    if( iPtr!=hdr+1 ) return SQLITE_CORRUPT_BKPT;
+    put2byte(&data[hdr+1], iFreeBlk);
+    put2byte(&data[hdr+5], iEnd);
+  }else{
+    /* Insert the new freeblock into the freelist */
+    put2byte(&data[iPtr], iStart);
+    put2byte(&data[iStart], iFreeBlk);
+    put2byte(&data[iStart+2], iSize);
+  }
+  pPage->nFree += iOrigSize;
+  return SQLITE_OK;
+}
+
+/*
+** Decode the flags byte (the first byte of the header) for a page
+** and initialize fields of the MemPage structure accordingly.
+**
+** Only the following combinations are supported.  Anything different
+** indicates a corrupt database files:
+**
+**         PTF_ZERODATA
+**         PTF_ZERODATA | PTF_LEAF
+**         PTF_LEAFDATA | PTF_INTKEY
+**         PTF_LEAFDATA | PTF_INTKEY | PTF_LEAF
+*/
+static int decodeFlags(MemPage *pPage, int flagByte){
+  BtShared *pBt;     /* A copy of pPage->pBt */
+
+  assert( pPage->hdrOffset==(pPage->pgno==1 ? 100 : 0) );
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  pPage->leaf = (u8)(flagByte>>3);  assert( PTF_LEAF == 1<<3 );
+  flagByte &= ~PTF_LEAF;
+  pPage->childPtrSize = 4-4*pPage->leaf;
+  pPage->xCellSize = cellSizePtr;
+  pBt = pPage->pBt;
+  if( flagByte==(PTF_LEAFDATA | PTF_INTKEY) ){
+    /* EVIDENCE-OF: R-07291-35328 A value of 5 (0x05) means the page is an
+    ** interior table b-tree page. */
+    assert( (PTF_LEAFDATA|PTF_INTKEY)==5 );
+    /* EVIDENCE-OF: R-26900-09176 A value of 13 (0x0d) means the page is a
+    ** leaf table b-tree page. */
+    assert( (PTF_LEAFDATA|PTF_INTKEY|PTF_LEAF)==13 );
+    pPage->intKey = 1;
+    if( pPage->leaf ){
+      pPage->intKeyLeaf = 1;
+      pPage->xParseCell = btreeParseCellPtr;
+    }else{
+      pPage->intKeyLeaf = 0;
+      pPage->xCellSize = cellSizePtrNoPayload;
+      pPage->xParseCell = btreeParseCellPtrNoPayload;
+    }
+    pPage->maxLocal = pBt->maxLeaf;
+    pPage->minLocal = pBt->minLeaf;
+  }else if( flagByte==PTF_ZERODATA ){
+    /* EVIDENCE-OF: R-43316-37308 A value of 2 (0x02) means the page is an
+    ** interior index b-tree page. */
+    assert( (PTF_ZERODATA)==2 );
+    /* EVIDENCE-OF: R-59615-42828 A value of 10 (0x0a) means the page is a
+    ** leaf index b-tree page. */
+    assert( (PTF_ZERODATA|PTF_LEAF)==10 );
+    pPage->intKey = 0;
+    pPage->intKeyLeaf = 0;
+    pPage->xParseCell = btreeParseCellPtrIndex;
+    pPage->maxLocal = pBt->maxLocal;
+    pPage->minLocal = pBt->minLocal;
+  }else{
+    /* EVIDENCE-OF: R-47608-56469 Any other value for the b-tree page type is
+    ** an error. */
+    return SQLITE_CORRUPT_BKPT;
+  }
+  pPage->max1bytePayload = pBt->max1bytePayload;
+  return SQLITE_OK;
+}
+
+/*
+** Initialize the auxiliary information for a disk block.
+**
+** Return SQLITE_OK on success.  If we see that the page does
+** not contain a well-formed database page, then return 
+** SQLITE_CORRUPT.  Note that a return of SQLITE_OK does not
+** guarantee that the page is well-formed.  It only shows that
+** we failed to detect any corruption.
+*/
+static int btreeInitPage(MemPage *pPage){
+
+  assert( pPage->pBt!=0 );
+  assert( pPage->pBt->db!=0 );
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  assert( pPage->pgno==sqlite3PagerPagenumber(pPage->pDbPage) );
+  assert( pPage == sqlite3PagerGetExtra(pPage->pDbPage) );
+  assert( pPage->aData == sqlite3PagerGetData(pPage->pDbPage) );
+
+  if( !pPage->isInit ){
+    u16 pc;            /* Address of a freeblock within pPage->aData[] */
+    u8 hdr;            /* Offset to beginning of page header */
+    u8 *data;          /* Equal to pPage->aData */
+    BtShared *pBt;        /* The main btree structure */
+    int usableSize;    /* Amount of usable space on each page */
+    u16 cellOffset;    /* Offset from start of page to first cell pointer */
+    int nFree;         /* Number of unused bytes on the page */
+    int top;           /* First byte of the cell content area */
+    int iCellFirst;    /* First allowable cell or freeblock offset */
+    int iCellLast;     /* Last possible cell or freeblock offset */
+
+    pBt = pPage->pBt;
+
+    hdr = pPage->hdrOffset;
+    data = pPage->aData;
+    /* EVIDENCE-OF: R-28594-02890 The one-byte flag at offset 0 indicating
+    ** the b-tree page type. */
+    if( decodeFlags(pPage, data[hdr]) ) return SQLITE_CORRUPT_BKPT;
+    assert( pBt->pageSize>=512 && pBt->pageSize<=65536 );
+    pPage->maskPage = (u16)(pBt->pageSize - 1);
+    pPage->nOverflow = 0;
+    usableSize = pBt->usableSize;
+    pPage->cellOffset = cellOffset = hdr + 8 + pPage->childPtrSize;
+    pPage->aDataEnd = &data[usableSize];
+    pPage->aCellIdx = &data[cellOffset];
+    pPage->aDataOfst = &data[pPage->childPtrSize];
+    /* EVIDENCE-OF: R-58015-48175 The two-byte integer at offset 5 designates
+    ** the start of the cell content area. A zero value for this integer is
+    ** interpreted as 65536. */
+    top = get2byteNotZero(&data[hdr+5]);
+    /* EVIDENCE-OF: R-37002-32774 The two-byte integer at offset 3 gives the
+    ** number of cells on the page. */
+    pPage->nCell = get2byte(&data[hdr+3]);
+    if( pPage->nCell>MX_CELL(pBt) ){
+      /* To many cells for a single page.  The page must be corrupt */
+      return SQLITE_CORRUPT_BKPT;
+    }
+    testcase( pPage->nCell==MX_CELL(pBt) );
+    /* EVIDENCE-OF: R-24089-57979 If a page contains no cells (which is only
+    ** possible for a root page of a table that contains no rows) then the
+    ** offset to the cell content area will equal the page size minus the
+    ** bytes of reserved space. */
+    assert( pPage->nCell>0 || top==usableSize || CORRUPT_DB );
+
+    /* A malformed database page might cause us to read past the end
+    ** of page when parsing a cell.  
+    **
+    ** The following block of code checks early to see if a cell extends
+    ** past the end of a page boundary and causes SQLITE_CORRUPT to be 
+    ** returned if it does.
+    */
+    iCellFirst = cellOffset + 2*pPage->nCell;
+    iCellLast = usableSize - 4;
+    if( pBt->db->flags & SQLITE_CellSizeCk ){
+      int i;            /* Index into the cell pointer array */
+      int sz;           /* Size of a cell */
+
+      if( !pPage->leaf ) iCellLast--;
+      for(i=0; i<pPage->nCell; i++){
+        pc = get2byteAligned(&data[cellOffset+i*2]);
+        testcase( pc==iCellFirst );
+        testcase( pc==iCellLast );
+        if( pc<iCellFirst || pc>iCellLast ){
+          return SQLITE_CORRUPT_BKPT;
+        }
+        sz = pPage->xCellSize(pPage, &data[pc]);
+        testcase( pc+sz==usableSize );
+        if( pc+sz>usableSize ){
+          return SQLITE_CORRUPT_BKPT;
+        }
+      }
+      if( !pPage->leaf ) iCellLast++;
+    }  
+
+    /* Compute the total free space on the page
+    ** EVIDENCE-OF: R-23588-34450 The two-byte integer at offset 1 gives the
+    ** start of the first freeblock on the page, or is zero if there are no
+    ** freeblocks. */
+    pc = get2byte(&data[hdr+1]);
+    nFree = data[hdr+7] + top;  /* Init nFree to non-freeblock free space */
+    while( pc>0 ){
+      u16 next, size;
+      if( pc<iCellFirst || pc>iCellLast ){
+        /* EVIDENCE-OF: R-55530-52930 In a well-formed b-tree page, there will
+        ** always be at least one cell before the first freeblock.
+        **
+        ** Or, the freeblock is off the end of the page
+        */
+        return SQLITE_CORRUPT_BKPT; 
+      }
+      next = get2byte(&data[pc]);
+      size = get2byte(&data[pc+2]);
+      if( (next>0 && next<=pc+size+3) || pc+size>usableSize ){
+        /* Free blocks must be in ascending order. And the last byte of
+        ** the free-block must lie on the database page.  */
+        return SQLITE_CORRUPT_BKPT; 
+      }
+      nFree = nFree + size;
+      pc = next;
+    }
+
+    /* At this point, nFree contains the sum of the offset to the start
+    ** of the cell-content area plus the number of free bytes within
+    ** the cell-content area. If this is greater than the usable-size
+    ** of the page, then the page must be corrupted. This check also
+    ** serves to verify that the offset to the start of the cell-content
+    ** area, according to the page header, lies within the page.
+    */
+    if( nFree>usableSize ){
+      return SQLITE_CORRUPT_BKPT; 
+    }
+    pPage->nFree = (u16)(nFree - iCellFirst);
+    pPage->isInit = 1;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Set up a raw page so that it looks like a database page holding
+** no entries.
+*/
+static void zeroPage(MemPage *pPage, int flags){
+  unsigned char *data = pPage->aData;
+  BtShared *pBt = pPage->pBt;
+  u8 hdr = pPage->hdrOffset;
+  u16 first;
+
+  assert( sqlite3PagerPagenumber(pPage->pDbPage)==pPage->pgno );
+  assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage );
+  assert( sqlite3PagerGetData(pPage->pDbPage) == data );
+  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  if( pBt->btsFlags & BTS_SECURE_DELETE ){
+    memset(&data[hdr], 0, pBt->usableSize - hdr);
+  }
+  data[hdr] = (char)flags;
+  first = hdr + ((flags&PTF_LEAF)==0 ? 12 : 8);
+  memset(&data[hdr+1], 0, 4);
+  data[hdr+7] = 0;
+  put2byte(&data[hdr+5], pBt->usableSize);
+  pPage->nFree = (u16)(pBt->usableSize - first);
+  decodeFlags(pPage, flags);
+  pPage->cellOffset = first;
+  pPage->aDataEnd = &data[pBt->usableSize];
+  pPage->aCellIdx = &data[first];
+  pPage->aDataOfst = &data[pPage->childPtrSize];
+  pPage->nOverflow = 0;
+  assert( pBt->pageSize>=512 && pBt->pageSize<=65536 );
+  pPage->maskPage = (u16)(pBt->pageSize - 1);
+  pPage->nCell = 0;
+  pPage->isInit = 1;
+}
+
+
+/*
+** Convert a DbPage obtained from the pager into a MemPage used by
+** the btree layer.
+*/
+static MemPage *btreePageFromDbPage(DbPage *pDbPage, Pgno pgno, BtShared *pBt){
+  MemPage *pPage = (MemPage*)sqlite3PagerGetExtra(pDbPage);
+  if( pgno!=pPage->pgno ){
+    pPage->aData = sqlite3PagerGetData(pDbPage);
+    pPage->pDbPage = pDbPage;
+    pPage->pBt = pBt;
+    pPage->pgno = pgno;
+    pPage->hdrOffset = pgno==1 ? 100 : 0;
+  }
+  assert( pPage->aData==sqlite3PagerGetData(pDbPage) );
+  return pPage; 
+}
+
+/*
+** Get a page from the pager.  Initialize the MemPage.pBt and
+** MemPage.aData elements if needed.  See also: btreeGetUnusedPage().
+**
+** If the PAGER_GET_NOCONTENT flag is set, it means that we do not care
+** about the content of the page at this time.  So do not go to the disk
+** to fetch the content.  Just fill in the content with zeros for now.
+** If in the future we call sqlite3PagerWrite() on this page, that
+** means we have started to be concerned about content and the disk
+** read should occur at that point.
+*/
+static int btreeGetPage(
+  BtShared *pBt,       /* The btree */
+  Pgno pgno,           /* Number of the page to fetch */
+  MemPage **ppPage,    /* Return the page in this parameter */
+  int flags            /* PAGER_GET_NOCONTENT or PAGER_GET_READONLY */
+){
+  int rc;
+  DbPage *pDbPage;
+
+  assert( flags==0 || flags==PAGER_GET_NOCONTENT || flags==PAGER_GET_READONLY );
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  rc = sqlite3PagerGet(pBt->pPager, pgno, (DbPage**)&pDbPage, flags);
+  if( rc ) return rc;
+  *ppPage = btreePageFromDbPage(pDbPage, pgno, pBt);
+  return SQLITE_OK;
+}
+
+/*
+** Retrieve a page from the pager cache. If the requested page is not
+** already in the pager cache return NULL. Initialize the MemPage.pBt and
+** MemPage.aData elements if needed.
+*/
+static MemPage *btreePageLookup(BtShared *pBt, Pgno pgno){
+  DbPage *pDbPage;
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  pDbPage = sqlite3PagerLookup(pBt->pPager, pgno);
+  if( pDbPage ){
+    return btreePageFromDbPage(pDbPage, pgno, pBt);
+  }
+  return 0;
+}
+
+/*
+** Return the size of the database file in pages. If there is any kind of
+** error, return ((unsigned int)-1).
+*/
+static Pgno btreePagecount(BtShared *pBt){
+  return pBt->nPage;
+}
+SQLITE_PRIVATE u32 sqlite3BtreeLastPage(Btree *p){
+  assert( sqlite3BtreeHoldsMutex(p) );
+  assert( ((p->pBt->nPage)&0x8000000)==0 );
+  return btreePagecount(p->pBt);
+}
+
+/*
+** Get a page from the pager and initialize it.
+**
+** If pCur!=0 then the page is being fetched as part of a moveToChild()
+** call.  Do additional sanity checking on the page in this case.
+** And if the fetch fails, this routine must decrement pCur->iPage.
+**
+** The page is fetched as read-write unless pCur is not NULL and is
+** a read-only cursor.
+**
+** If an error occurs, then *ppPage is undefined. It
+** may remain unchanged, or it may be set to an invalid value.
+*/
+static int getAndInitPage(
+  BtShared *pBt,                  /* The database file */
+  Pgno pgno,                      /* Number of the page to get */
+  MemPage **ppPage,               /* Write the page pointer here */
+  BtCursor *pCur,                 /* Cursor to receive the page, or NULL */
+  int bReadOnly                   /* True for a read-only page */
+){
+  int rc;
+  DbPage *pDbPage;
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( pCur==0 || ppPage==&pCur->apPage[pCur->iPage] );
+  assert( pCur==0 || bReadOnly==pCur->curPagerFlags );
+  assert( pCur==0 || pCur->iPage>0 );
+
+  if( pgno>btreePagecount(pBt) ){
+    rc = SQLITE_CORRUPT_BKPT;
+    goto getAndInitPage_error;
+  }
+  rc = sqlite3PagerGet(pBt->pPager, pgno, (DbPage**)&pDbPage, bReadOnly);
+  if( rc ){
+    goto getAndInitPage_error;
+  }
+  *ppPage = (MemPage*)sqlite3PagerGetExtra(pDbPage);
+  if( (*ppPage)->isInit==0 ){
+    btreePageFromDbPage(pDbPage, pgno, pBt);
+    rc = btreeInitPage(*ppPage);
+    if( rc!=SQLITE_OK ){
+      releasePage(*ppPage);
+      goto getAndInitPage_error;
+    }
+  }
+  assert( (*ppPage)->pgno==pgno );
+  assert( (*ppPage)->aData==sqlite3PagerGetData(pDbPage) );
+
+  /* If obtaining a child page for a cursor, we must verify that the page is
+  ** compatible with the root page. */
+  if( pCur && ((*ppPage)->nCell<1 || (*ppPage)->intKey!=pCur->curIntKey) ){
+    rc = SQLITE_CORRUPT_BKPT;
+    releasePage(*ppPage);
+    goto getAndInitPage_error;
+  }
+  return SQLITE_OK;
+
+getAndInitPage_error:
+  if( pCur ) pCur->iPage--;
+  testcase( pgno==0 );
+  assert( pgno!=0 || rc==SQLITE_CORRUPT );
+  return rc;
+}
+
+/*
+** Release a MemPage.  This should be called once for each prior
+** call to btreeGetPage.
+*/
+static void releasePageNotNull(MemPage *pPage){
+  assert( pPage->aData );
+  assert( pPage->pBt );
+  assert( pPage->pDbPage!=0 );
+  assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage );
+  assert( sqlite3PagerGetData(pPage->pDbPage)==pPage->aData );
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  sqlite3PagerUnrefNotNull(pPage->pDbPage);
+}
+static void releasePage(MemPage *pPage){
+  if( pPage ) releasePageNotNull(pPage);
+}
+
+/*
+** Get an unused page.
+**
+** This works just like btreeGetPage() with the addition:
+**
+**   *  If the page is already in use for some other purpose, immediately
+**      release it and return an SQLITE_CURRUPT error.
+**   *  Make sure the isInit flag is clear
+*/
+static int btreeGetUnusedPage(
+  BtShared *pBt,       /* The btree */
+  Pgno pgno,           /* Number of the page to fetch */
+  MemPage **ppPage,    /* Return the page in this parameter */
+  int flags            /* PAGER_GET_NOCONTENT or PAGER_GET_READONLY */
+){
+  int rc = btreeGetPage(pBt, pgno, ppPage, flags);
+  if( rc==SQLITE_OK ){
+    if( sqlite3PagerPageRefcount((*ppPage)->pDbPage)>1 ){
+      releasePage(*ppPage);
+      *ppPage = 0;
+      return SQLITE_CORRUPT_BKPT;
+    }
+    (*ppPage)->isInit = 0;
+  }else{
+    *ppPage = 0;
+  }
+  return rc;
+}
+
+
+/*
+** During a rollback, when the pager reloads information into the cache
+** so that the cache is restored to its original state at the start of
+** the transaction, for each page restored this routine is called.
+**
+** This routine needs to reset the extra data section at the end of the
+** page to agree with the restored data.
+*/
+static void pageReinit(DbPage *pData){
+  MemPage *pPage;
+  pPage = (MemPage *)sqlite3PagerGetExtra(pData);
+  assert( sqlite3PagerPageRefcount(pData)>0 );
+  if( pPage->isInit ){
+    assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+    pPage->isInit = 0;
+    if( sqlite3PagerPageRefcount(pData)>1 ){
+      /* pPage might not be a btree page;  it might be an overflow page
+      ** or ptrmap page or a free page.  In those cases, the following
+      ** call to btreeInitPage() will likely return SQLITE_CORRUPT.
+      ** But no harm is done by this.  And it is very important that
+      ** btreeInitPage() be called on every btree page so we make
+      ** the call for every page that comes in for re-initing. */
+      btreeInitPage(pPage);
+    }
+  }
+}
+
+/*
+** Invoke the busy handler for a btree.
+*/
+static int btreeInvokeBusyHandler(void *pArg){
+  BtShared *pBt = (BtShared*)pArg;
+  assert( pBt->db );
+  assert( sqlite3_mutex_held(pBt->db->mutex) );
+  return sqlite3InvokeBusyHandler(&pBt->db->busyHandler);
+}
+
+/*
+** Open a database file.
+** 
+** zFilename is the name of the database file.  If zFilename is NULL
+** then an ephemeral database is created.  The ephemeral database might
+** be exclusively in memory, or it might use a disk-based memory cache.
+** Either way, the ephemeral database will be automatically deleted 
+** when sqlite3BtreeClose() is called.
+**
+** If zFilename is ":memory:" then an in-memory database is created
+** that is automatically destroyed when it is closed.
+**
+** The "flags" parameter is a bitmask that might contain bits like
+** BTREE_OMIT_JOURNAL and/or BTREE_MEMORY.
+**
+** If the database is already opened in the same database connection
+** and we are in shared cache mode, then the open will fail with an
+** SQLITE_CONSTRAINT error.  We cannot allow two or more BtShared
+** objects in the same database connection since doing so will lead
+** to problems with locking.
+*/
+SQLITE_PRIVATE int sqlite3BtreeOpen(
+  sqlite3_vfs *pVfs,      /* VFS to use for this b-tree */
+  const char *zFilename,  /* Name of the file containing the BTree database */
+  sqlite3 *db,            /* Associated database handle */
+  Btree **ppBtree,        /* Pointer to new Btree object written here */
+  int flags,              /* Options */
+  int vfsFlags            /* Flags passed through to sqlite3_vfs.xOpen() */
+){
+  BtShared *pBt = 0;             /* Shared part of btree structure */
+  Btree *p;                      /* Handle to return */
+  sqlite3_mutex *mutexOpen = 0;  /* Prevents a race condition. Ticket #3537 */
+  int rc = SQLITE_OK;            /* Result code from this function */
+  u8 nReserve;                   /* Byte of unused space on each page */
+  unsigned char zDbHeader[100];  /* Database header content */
+
+  /* True if opening an ephemeral, temporary database */
+  const int isTempDb = zFilename==0 || zFilename[0]==0;
+
+  /* Set the variable isMemdb to true for an in-memory database, or 
+  ** false for a file-based database.
+  */
+#ifdef SQLITE_OMIT_MEMORYDB
+  const int isMemdb = 0;
+#else
+  const int isMemdb = (zFilename && strcmp(zFilename, ":memory:")==0)
+                       || (isTempDb && sqlite3TempInMemory(db))
+                       || (vfsFlags & SQLITE_OPEN_MEMORY)!=0;
+#endif
+
+  assert( db!=0 );
+  assert( pVfs!=0 );
+  assert( sqlite3_mutex_held(db->mutex) );
+  assert( (flags&0xff)==flags );   /* flags fit in 8 bits */
+
+  /* Only a BTREE_SINGLE database can be BTREE_UNORDERED */
+  assert( (flags & BTREE_UNORDERED)==0 || (flags & BTREE_SINGLE)!=0 );
+
+  /* A BTREE_SINGLE database is always a temporary and/or ephemeral */
+  assert( (flags & BTREE_SINGLE)==0 || isTempDb );
+
+  if( isMemdb ){
+    flags |= BTREE_MEMORY;
+  }
+  if( (vfsFlags & SQLITE_OPEN_MAIN_DB)!=0 && (isMemdb || isTempDb) ){
+    vfsFlags = (vfsFlags & ~SQLITE_OPEN_MAIN_DB) | SQLITE_OPEN_TEMP_DB;
+  }
+  p = sqlite3MallocZero(sizeof(Btree));
+  if( !p ){
+    return SQLITE_NOMEM_BKPT;
+  }
+  p->inTrans = TRANS_NONE;
+  p->db = db;
+#ifndef SQLITE_OMIT_SHARED_CACHE
+  p->lock.pBtree = p;
+  p->lock.iTable = 1;
+#endif
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
+  /*
+  ** If this Btree is a candidate for shared cache, try to find an
+  ** existing BtShared object that we can share with
+  */
+  if( isTempDb==0 && (isMemdb==0 || (vfsFlags&SQLITE_OPEN_URI)!=0) ){
+    if( vfsFlags & SQLITE_OPEN_SHAREDCACHE ){
+      int nFilename = sqlite3Strlen30(zFilename)+1;
+      int nFullPathname = pVfs->mxPathname+1;
+      char *zFullPathname = sqlite3Malloc(MAX(nFullPathname,nFilename));
+      MUTEX_LOGIC( sqlite3_mutex *mutexShared; )
+
+      p->sharable = 1;
+      if( !zFullPathname ){
+        sqlite3_free(p);
+        return SQLITE_NOMEM_BKPT;
+      }
+      if( isMemdb ){
+        memcpy(zFullPathname, zFilename, nFilename);
+      }else{
+        rc = sqlite3OsFullPathname(pVfs, zFilename,
+                                   nFullPathname, zFullPathname);
+        if( rc ){
+          sqlite3_free(zFullPathname);
+          sqlite3_free(p);
+          return rc;
+        }
+      }
+#if SQLITE_THREADSAFE
+      mutexOpen = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_OPEN);
+      sqlite3_mutex_enter(mutexOpen);
+      mutexShared = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
+      sqlite3_mutex_enter(mutexShared);
+#endif
+      for(pBt=GLOBAL(BtShared*,sqlite3SharedCacheList); pBt; pBt=pBt->pNext){
+        assert( pBt->nRef>0 );
+        if( 0==strcmp(zFullPathname, sqlite3PagerFilename(pBt->pPager, 0))
+                 && sqlite3PagerVfs(pBt->pPager)==pVfs ){
+          int iDb;
+          for(iDb=db->nDb-1; iDb>=0; iDb--){
+            Btree *pExisting = db->aDb[iDb].pBt;
+            if( pExisting && pExisting->pBt==pBt ){
+              sqlite3_mutex_leave(mutexShared);
+              sqlite3_mutex_leave(mutexOpen);
+              sqlite3_free(zFullPathname);
+              sqlite3_free(p);
+              return SQLITE_CONSTRAINT;
+            }
+          }
+          p->pBt = pBt;
+          pBt->nRef++;
+          break;
+        }
+      }
+      sqlite3_mutex_leave(mutexShared);
+      sqlite3_free(zFullPathname);
+    }
+#ifdef SQLITE_DEBUG
+    else{
+      /* In debug mode, we mark all persistent databases as sharable
+      ** even when they are not.  This exercises the locking code and
+      ** gives more opportunity for asserts(sqlite3_mutex_held())
+      ** statements to find locking problems.
+      */
+      p->sharable = 1;
+    }
+#endif
+  }
+#endif
+  if( pBt==0 ){
+    /*
+    ** The following asserts make sure that structures used by the btree are
+    ** the right size.  This is to guard against size changes that result
+    ** when compiling on a different architecture.
+    */
+    assert( sizeof(i64)==8 );
+    assert( sizeof(u64)==8 );
+    assert( sizeof(u32)==4 );
+    assert( sizeof(u16)==2 );
+    assert( sizeof(Pgno)==4 );
+  
+    pBt = sqlite3MallocZero( sizeof(*pBt) );
+    if( pBt==0 ){
+      rc = SQLITE_NOMEM_BKPT;
+      goto btree_open_out;
+    }
+    rc = sqlite3PagerOpen(pVfs, &pBt->pPager, zFilename,
+                          EXTRA_SIZE, flags, vfsFlags, pageReinit);
+    if( rc==SQLITE_OK ){
+      sqlite3PagerSetMmapLimit(pBt->pPager, db->szMmap);
+      rc = sqlite3PagerReadFileheader(pBt->pPager,sizeof(zDbHeader),zDbHeader);
+    }
+    if( rc!=SQLITE_OK ){
+      goto btree_open_out;
+    }
+    pBt->openFlags = (u8)flags;
+    pBt->db = db;
+    sqlite3PagerSetBusyhandler(pBt->pPager, btreeInvokeBusyHandler, pBt);
+    p->pBt = pBt;
+  
+    pBt->pCursor = 0;
+    pBt->pPage1 = 0;
+    if( sqlite3PagerIsreadonly(pBt->pPager) ) pBt->btsFlags |= BTS_READ_ONLY;
+#ifdef SQLITE_SECURE_DELETE
+    pBt->btsFlags |= BTS_SECURE_DELETE;
+#endif
+    /* EVIDENCE-OF: R-51873-39618 The page size for a database file is
+    ** determined by the 2-byte integer located at an offset of 16 bytes from
+    ** the beginning of the database file. */
+    pBt->pageSize = (zDbHeader[16]<<8) | (zDbHeader[17]<<16);
+    if( pBt->pageSize<512 || pBt->pageSize>SQLITE_MAX_PAGE_SIZE
+         || ((pBt->pageSize-1)&pBt->pageSize)!=0 ){
+      pBt->pageSize = 0;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+      /* If the magic name ":memory:" will create an in-memory database, then
+      ** leave the autoVacuum mode at 0 (do not auto-vacuum), even if
+      ** SQLITE_DEFAULT_AUTOVACUUM is true. On the other hand, if
+      ** SQLITE_OMIT_MEMORYDB has been defined, then ":memory:" is just a
+      ** regular file-name. In this case the auto-vacuum applies as per normal.
+      */
+      if( zFilename && !isMemdb ){
+        pBt->autoVacuum = (SQLITE_DEFAULT_AUTOVACUUM ? 1 : 0);
+        pBt->incrVacuum = (SQLITE_DEFAULT_AUTOVACUUM==2 ? 1 : 0);
+      }
+#endif
+      nReserve = 0;
+    }else{
+      /* EVIDENCE-OF: R-37497-42412 The size of the reserved region is
+      ** determined by the one-byte unsigned integer found at an offset of 20
+      ** into the database file header. */
+      nReserve = zDbHeader[20];
+      pBt->btsFlags |= BTS_PAGESIZE_FIXED;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+      pBt->autoVacuum = (get4byte(&zDbHeader[36 + 4*4])?1:0);
+      pBt->incrVacuum = (get4byte(&zDbHeader[36 + 7*4])?1:0);
+#endif
+    }
+    rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize, nReserve);
+    if( rc ) goto btree_open_out;
+    pBt->usableSize = pBt->pageSize - nReserve;
+    assert( (pBt->pageSize & 7)==0 );  /* 8-byte alignment of pageSize */
+   
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
+    /* Add the new BtShared object to the linked list sharable BtShareds.
+    */
+    pBt->nRef = 1;
+    if( p->sharable ){
+      MUTEX_LOGIC( sqlite3_mutex *mutexShared; )
+      MUTEX_LOGIC( mutexShared = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);)
+      if( SQLITE_THREADSAFE && sqlite3GlobalConfig.bCoreMutex ){
+        pBt->mutex = sqlite3MutexAlloc(SQLITE_MUTEX_FAST);
+        if( pBt->mutex==0 ){
+          rc = SQLITE_NOMEM_BKPT;
+          goto btree_open_out;
+        }
+      }
+      sqlite3_mutex_enter(mutexShared);
+      pBt->pNext = GLOBAL(BtShared*,sqlite3SharedCacheList);
+      GLOBAL(BtShared*,sqlite3SharedCacheList) = pBt;
+      sqlite3_mutex_leave(mutexShared);
+    }
+#endif
+  }
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
+  /* If the new Btree uses a sharable pBtShared, then link the new
+  ** Btree into the list of all sharable Btrees for the same connection.
+  ** The list is kept in ascending order by pBt address.
+  */
+  if( p->sharable ){
+    int i;
+    Btree *pSib;
+    for(i=0; i<db->nDb; i++){
+      if( (pSib = db->aDb[i].pBt)!=0 && pSib->sharable ){
+        while( pSib->pPrev ){ pSib = pSib->pPrev; }
+        if( (uptr)p->pBt<(uptr)pSib->pBt ){
+          p->pNext = pSib;
+          p->pPrev = 0;
+          pSib->pPrev = p;
+        }else{
+          while( pSib->pNext && (uptr)pSib->pNext->pBt<(uptr)p->pBt ){
+            pSib = pSib->pNext;
+          }
+          p->pNext = pSib->pNext;
+          p->pPrev = pSib;
+          if( p->pNext ){
+            p->pNext->pPrev = p;
+          }
+          pSib->pNext = p;
+        }
+        break;
+      }
+    }
+  }
+#endif
+  *ppBtree = p;
+
+btree_open_out:
+  if( rc!=SQLITE_OK ){
+    if( pBt && pBt->pPager ){
+      sqlite3PagerClose(pBt->pPager);
+    }
+    sqlite3_free(pBt);
+    sqlite3_free(p);
+    *ppBtree = 0;
+  }else{
+    /* If the B-Tree was successfully opened, set the pager-cache size to the
+    ** default value. Except, when opening on an existing shared pager-cache,
+    ** do not change the pager-cache size.
+    */
+    if( sqlite3BtreeSchema(p, 0, 0)==0 ){
+      sqlite3PagerSetCachesize(p->pBt->pPager, SQLITE_DEFAULT_CACHE_SIZE);
+    }
+  }
+  if( mutexOpen ){
+    assert( sqlite3_mutex_held(mutexOpen) );
+    sqlite3_mutex_leave(mutexOpen);
+  }
+  assert( rc!=SQLITE_OK || sqlite3BtreeConnectionCount(*ppBtree)>0 );
+  return rc;
+}
+
+/*
+** Decrement the BtShared.nRef counter.  When it reaches zero,
+** remove the BtShared structure from the sharing list.  Return
+** true if the BtShared.nRef counter reaches zero and return
+** false if it is still positive.
+*/
+static int removeFromSharingList(BtShared *pBt){
+#ifndef SQLITE_OMIT_SHARED_CACHE
+  MUTEX_LOGIC( sqlite3_mutex *pMaster; )
+  BtShared *pList;
+  int removed = 0;
+
+  assert( sqlite3_mutex_notheld(pBt->mutex) );
+  MUTEX_LOGIC( pMaster = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); )
+  sqlite3_mutex_enter(pMaster);
+  pBt->nRef--;
+  if( pBt->nRef<=0 ){
+    if( GLOBAL(BtShared*,sqlite3SharedCacheList)==pBt ){
+      GLOBAL(BtShared*,sqlite3SharedCacheList) = pBt->pNext;
+    }else{
+      pList = GLOBAL(BtShared*,sqlite3SharedCacheList);
+      while( ALWAYS(pList) && pList->pNext!=pBt ){
+        pList=pList->pNext;
+      }
+      if( ALWAYS(pList) ){
+        pList->pNext = pBt->pNext;
+      }
+    }
+    if( SQLITE_THREADSAFE ){
+      sqlite3_mutex_free(pBt->mutex);
+    }
+    removed = 1;
+  }
+  sqlite3_mutex_leave(pMaster);
+  return removed;
+#else
+  return 1;
+#endif
+}
+
+/*
+** Make sure pBt->pTmpSpace points to an allocation of 
+** MX_CELL_SIZE(pBt) bytes with a 4-byte prefix for a left-child
+** pointer.
+*/
+static void allocateTempSpace(BtShared *pBt){
+  if( !pBt->pTmpSpace ){
+    pBt->pTmpSpace = sqlite3PageMalloc( pBt->pageSize );
+
+    /* One of the uses of pBt->pTmpSpace is to format cells before
+    ** inserting them into a leaf page (function fillInCell()). If
+    ** a cell is less than 4 bytes in size, it is rounded up to 4 bytes
+    ** by the various routines that manipulate binary cells. Which
+    ** can mean that fillInCell() only initializes the first 2 or 3
+    ** bytes of pTmpSpace, but that the first 4 bytes are copied from
+    ** it into a database page. This is not actually a problem, but it
+    ** does cause a valgrind error when the 1 or 2 bytes of unitialized 
+    ** data is passed to system call write(). So to avoid this error,
+    ** zero the first 4 bytes of temp space here.
+    **
+    ** Also:  Provide four bytes of initialized space before the
+    ** beginning of pTmpSpace as an area available to prepend the
+    ** left-child pointer to the beginning of a cell.
+    */
+    if( pBt->pTmpSpace ){
+      memset(pBt->pTmpSpace, 0, 8);
+      pBt->pTmpSpace += 4;
+    }
+  }
+}
+
+/*
+** Free the pBt->pTmpSpace allocation
+*/
+static void freeTempSpace(BtShared *pBt){
+  if( pBt->pTmpSpace ){
+    pBt->pTmpSpace -= 4;
+    sqlite3PageFree(pBt->pTmpSpace);
+    pBt->pTmpSpace = 0;
+  }
+}
+
+/*
+** Close an open database and invalidate all cursors.
+*/
+SQLITE_PRIVATE int sqlite3BtreeClose(Btree *p){
+  BtShared *pBt = p->pBt;
+  BtCursor *pCur;
+
+  /* Close all cursors opened via this handle.  */
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  sqlite3BtreeEnter(p);
+  pCur = pBt->pCursor;
+  while( pCur ){
+    BtCursor *pTmp = pCur;
+    pCur = pCur->pNext;
+    if( pTmp->pBtree==p ){
+      sqlite3BtreeCloseCursor(pTmp);
+    }
+  }
+
+  /* Rollback any active transaction and free the handle structure.
+  ** The call to sqlite3BtreeRollback() drops any table-locks held by
+  ** this handle.
+  */
+  sqlite3BtreeRollback(p, SQLITE_OK, 0);
+  sqlite3BtreeLeave(p);
+
+  /* If there are still other outstanding references to the shared-btree
+  ** structure, return now. The remainder of this procedure cleans 
+  ** up the shared-btree.
+  */
+  assert( p->wantToLock==0 && p->locked==0 );
+  if( !p->sharable || removeFromSharingList(pBt) ){
+    /* The pBt is no longer on the sharing list, so we can access
+    ** it without having to hold the mutex.
+    **
+    ** Clean out and delete the BtShared object.
+    */
+    assert( !pBt->pCursor );
+    sqlite3PagerClose(pBt->pPager);
+    if( pBt->xFreeSchema && pBt->pSchema ){
+      pBt->xFreeSchema(pBt->pSchema);
+    }
+    sqlite3DbFree(0, pBt->pSchema);
+    freeTempSpace(pBt);
+    sqlite3_free(pBt);
+  }
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+  assert( p->wantToLock==0 );
+  assert( p->locked==0 );
+  if( p->pPrev ) p->pPrev->pNext = p->pNext;
+  if( p->pNext ) p->pNext->pPrev = p->pPrev;
+#endif
+
+  sqlite3_free(p);
+  return SQLITE_OK;
+}
+
+/*
+** Change the "soft" limit on the number of pages in the cache.
+** Unused and unmodified pages will be recycled when the number of
+** pages in the cache exceeds this soft limit.  But the size of the
+** cache is allowed to grow larger than this limit if it contains
+** dirty pages or pages still in active use.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSetCacheSize(Btree *p, int mxPage){
+  BtShared *pBt = p->pBt;
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  sqlite3BtreeEnter(p);
+  sqlite3PagerSetCachesize(pBt->pPager, mxPage);
+  sqlite3BtreeLeave(p);
+  return SQLITE_OK;
+}
+
+/*
+** Change the "spill" limit on the number of pages in the cache.
+** If the number of pages exceeds this limit during a write transaction,
+** the pager might attempt to "spill" pages to the journal early in
+** order to free up memory.
+**
+** The value returned is the current spill size.  If zero is passed
+** as an argument, no changes are made to the spill size setting, so
+** using mxPage of 0 is a way to query the current spill size.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSetSpillSize(Btree *p, int mxPage){
+  BtShared *pBt = p->pBt;
+  int res;
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  sqlite3BtreeEnter(p);
+  res = sqlite3PagerSetSpillsize(pBt->pPager, mxPage);
+  sqlite3BtreeLeave(p);
+  return res;
+}
+
+#if SQLITE_MAX_MMAP_SIZE>0
+/*
+** Change the limit on the amount of the database file that may be
+** memory mapped.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSetMmapLimit(Btree *p, sqlite3_int64 szMmap){
+  BtShared *pBt = p->pBt;
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  sqlite3BtreeEnter(p);
+  sqlite3PagerSetMmapLimit(pBt->pPager, szMmap);
+  sqlite3BtreeLeave(p);
+  return SQLITE_OK;
+}
+#endif /* SQLITE_MAX_MMAP_SIZE>0 */
+
+/*
+** Change the way data is synced to disk in order to increase or decrease
+** how well the database resists damage due to OS crashes and power
+** failures.  Level 1 is the same as asynchronous (no syncs() occur and
+** there is a high probability of damage)  Level 2 is the default.  There
+** is a very low but non-zero probability of damage.  Level 3 reduces the
+** probability of damage to near zero but with a write performance reduction.
+*/
+#ifndef SQLITE_OMIT_PAGER_PRAGMAS
+SQLITE_PRIVATE int sqlite3BtreeSetPagerFlags(
+  Btree *p,              /* The btree to set the safety level on */
+  unsigned pgFlags       /* Various PAGER_* flags */
+){
+  BtShared *pBt = p->pBt;
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  sqlite3BtreeEnter(p);
+  sqlite3PagerSetFlags(pBt->pPager, pgFlags);
+  sqlite3BtreeLeave(p);
+  return SQLITE_OK;
+}
+#endif
+
+/*
+** Change the default pages size and the number of reserved bytes per page.
+** Or, if the page size has already been fixed, return SQLITE_READONLY 
+** without changing anything.
+**
+** The page size must be a power of 2 between 512 and 65536.  If the page
+** size supplied does not meet this constraint then the page size is not
+** changed.
+**
+** Page sizes are constrained to be a power of two so that the region
+** of the database file used for locking (beginning at PENDING_BYTE,
+** the first byte past the 1GB boundary, 0x40000000) needs to occur
+** at the beginning of a page.
+**
+** If parameter nReserve is less than zero, then the number of reserved
+** bytes per page is left unchanged.
+**
+** If the iFix!=0 then the BTS_PAGESIZE_FIXED flag is set so that the page size
+** and autovacuum mode can no longer be changed.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSetPageSize(Btree *p, int pageSize, int nReserve, int iFix){
+  int rc = SQLITE_OK;
+  BtShared *pBt = p->pBt;
+  assert( nReserve>=-1 && nReserve<=255 );
+  sqlite3BtreeEnter(p);
+#if SQLITE_HAS_CODEC
+  if( nReserve>pBt->optimalReserve ) pBt->optimalReserve = (u8)nReserve;
+#endif
+  if( pBt->btsFlags & BTS_PAGESIZE_FIXED ){
+    sqlite3BtreeLeave(p);
+    return SQLITE_READONLY;
+  }
+  if( nReserve<0 ){
+    nReserve = pBt->pageSize - pBt->usableSize;
+  }
+  assert( nReserve>=0 && nReserve<=255 );
+  if( pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE &&
+        ((pageSize-1)&pageSize)==0 ){
+    assert( (pageSize & 7)==0 );
+    assert( !pBt->pCursor );
+    pBt->pageSize = (u32)pageSize;
+    freeTempSpace(pBt);
+  }
+  rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize, nReserve);
+  pBt->usableSize = pBt->pageSize - (u16)nReserve;
+  if( iFix ) pBt->btsFlags |= BTS_PAGESIZE_FIXED;
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+/*
+** Return the currently defined page size
+*/
+SQLITE_PRIVATE int sqlite3BtreeGetPageSize(Btree *p){
+  return p->pBt->pageSize;
+}
+
+/*
+** This function is similar to sqlite3BtreeGetReserve(), except that it
+** may only be called if it is guaranteed that the b-tree mutex is already
+** held.
+**
+** This is useful in one special case in the backup API code where it is
+** known that the shared b-tree mutex is held, but the mutex on the 
+** database handle that owns *p is not. In this case if sqlite3BtreeEnter()
+** were to be called, it might collide with some other operation on the
+** database handle that owns *p, causing undefined behavior.
+*/
+SQLITE_PRIVATE int sqlite3BtreeGetReserveNoMutex(Btree *p){
+  int n;
+  assert( sqlite3_mutex_held(p->pBt->mutex) );
+  n = p->pBt->pageSize - p->pBt->usableSize;
+  return n;
+}
+
+/*
+** Return the number of bytes of space at the end of every page that
+** are intentually left unused.  This is the "reserved" space that is
+** sometimes used by extensions.
+**
+** If SQLITE_HAS_MUTEX is defined then the number returned is the
+** greater of the current reserved space and the maximum requested
+** reserve space.
+*/
+SQLITE_PRIVATE int sqlite3BtreeGetOptimalReserve(Btree *p){
+  int n;
+  sqlite3BtreeEnter(p);
+  n = sqlite3BtreeGetReserveNoMutex(p);
+#ifdef SQLITE_HAS_CODEC
+  if( n<p->pBt->optimalReserve ) n = p->pBt->optimalReserve;
+#endif
+  sqlite3BtreeLeave(p);
+  return n;
+}
+
+
+/*
+** Set the maximum page count for a database if mxPage is positive.
+** No changes are made if mxPage is 0 or negative.
+** Regardless of the value of mxPage, return the maximum page count.
+*/
+SQLITE_PRIVATE int sqlite3BtreeMaxPageCount(Btree *p, int mxPage){
+  int n;
+  sqlite3BtreeEnter(p);
+  n = sqlite3PagerMaxPageCount(p->pBt->pPager, mxPage);
+  sqlite3BtreeLeave(p);
+  return n;
+}
+
+/*
+** Set the BTS_SECURE_DELETE flag if newFlag is 0 or 1.  If newFlag is -1,
+** then make no changes.  Always return the value of the BTS_SECURE_DELETE
+** setting after the change.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSecureDelete(Btree *p, int newFlag){
+  int b;
+  if( p==0 ) return 0;
+  sqlite3BtreeEnter(p);
+  if( newFlag>=0 ){
+    p->pBt->btsFlags &= ~BTS_SECURE_DELETE;
+    if( newFlag ) p->pBt->btsFlags |= BTS_SECURE_DELETE;
+  } 
+  b = (p->pBt->btsFlags & BTS_SECURE_DELETE)!=0;
+  sqlite3BtreeLeave(p);
+  return b;
+}
+
+/*
+** Change the 'auto-vacuum' property of the database. If the 'autoVacuum'
+** parameter is non-zero, then auto-vacuum mode is enabled. If zero, it
+** is disabled. The default value for the auto-vacuum property is 
+** determined by the SQLITE_DEFAULT_AUTOVACUUM macro.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSetAutoVacuum(Btree *p, int autoVacuum){
+#ifdef SQLITE_OMIT_AUTOVACUUM
+  return SQLITE_READONLY;
+#else
+  BtShared *pBt = p->pBt;
+  int rc = SQLITE_OK;
+  u8 av = (u8)autoVacuum;
+
+  sqlite3BtreeEnter(p);
+  if( (pBt->btsFlags & BTS_PAGESIZE_FIXED)!=0 && (av ?1:0)!=pBt->autoVacuum ){
+    rc = SQLITE_READONLY;
+  }else{
+    pBt->autoVacuum = av ?1:0;
+    pBt->incrVacuum = av==2 ?1:0;
+  }
+  sqlite3BtreeLeave(p);
+  return rc;
+#endif
+}
+
+/*
+** Return the value of the 'auto-vacuum' property. If auto-vacuum is 
+** enabled 1 is returned. Otherwise 0.
+*/
+SQLITE_PRIVATE int sqlite3BtreeGetAutoVacuum(Btree *p){
+#ifdef SQLITE_OMIT_AUTOVACUUM
+  return BTREE_AUTOVACUUM_NONE;
+#else
+  int rc;
+  sqlite3BtreeEnter(p);
+  rc = (
+    (!p->pBt->autoVacuum)?BTREE_AUTOVACUUM_NONE:
+    (!p->pBt->incrVacuum)?BTREE_AUTOVACUUM_FULL:
+    BTREE_AUTOVACUUM_INCR
+  );
+  sqlite3BtreeLeave(p);
+  return rc;
+#endif
+}
+
+
+/*
+** Get a reference to pPage1 of the database file.  This will
+** also acquire a readlock on that file.
+**
+** SQLITE_OK is returned on success.  If the file is not a
+** well-formed database file, then SQLITE_CORRUPT is returned.
+** SQLITE_BUSY is returned if the database is locked.  SQLITE_NOMEM
+** is returned if we run out of memory. 
+*/
+static int lockBtree(BtShared *pBt){
+  int rc;              /* Result code from subfunctions */
+  MemPage *pPage1;     /* Page 1 of the database file */
+  int nPage;           /* Number of pages in the database */
+  int nPageFile = 0;   /* Number of pages in the database file */
+  int nPageHeader;     /* Number of pages in the database according to hdr */
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( pBt->pPage1==0 );
+  rc = sqlite3PagerSharedLock(pBt->pPager);
+  if( rc!=SQLITE_OK ) return rc;
+  rc = btreeGetPage(pBt, 1, &pPage1, 0);
+  if( rc!=SQLITE_OK ) return rc;
+
+  /* Do some checking to help insure the file we opened really is
+  ** a valid database file. 
+  */
+  nPage = nPageHeader = get4byte(28+(u8*)pPage1->aData);
+  sqlite3PagerPagecount(pBt->pPager, &nPageFile);
+  if( nPage==0 || memcmp(24+(u8*)pPage1->aData, 92+(u8*)pPage1->aData,4)!=0 ){
+    nPage = nPageFile;
+  }
+  if( nPage>0 ){
+    u32 pageSize;
+    u32 usableSize;
+    u8 *page1 = pPage1->aData;
+    rc = SQLITE_NOTADB;
+    /* EVIDENCE-OF: R-43737-39999 Every valid SQLite database file begins
+    ** with the following 16 bytes (in hex): 53 51 4c 69 74 65 20 66 6f 72 6d
+    ** 61 74 20 33 00. */
+    if( memcmp(page1, zMagicHeader, 16)!=0 ){
+      goto page1_init_failed;
+    }
+
+#ifdef SQLITE_OMIT_WAL
+    if( page1[18]>1 ){
+      pBt->btsFlags |= BTS_READ_ONLY;
+    }
+    if( page1[19]>1 ){
+      goto page1_init_failed;
+    }
+#else
+    if( page1[18]>2 ){
+      pBt->btsFlags |= BTS_READ_ONLY;
+    }
+    if( page1[19]>2 ){
+      goto page1_init_failed;
+    }
+
+    /* If the write version is set to 2, this database should be accessed
+    ** in WAL mode. If the log is not already open, open it now. Then 
+    ** return SQLITE_OK and return without populating BtShared.pPage1.
+    ** The caller detects this and calls this function again. This is
+    ** required as the version of page 1 currently in the page1 buffer
+    ** may not be the latest version - there may be a newer one in the log
+    ** file.
+    */
+    if( page1[19]==2 && (pBt->btsFlags & BTS_NO_WAL)==0 ){
+      int isOpen = 0;
+      rc = sqlite3PagerOpenWal(pBt->pPager, &isOpen);
+      if( rc!=SQLITE_OK ){
+        goto page1_init_failed;
+      }else{
+#if SQLITE_DEFAULT_SYNCHRONOUS!=SQLITE_DEFAULT_WAL_SYNCHRONOUS
+        sqlite3 *db;
+        Db *pDb;
+        if( (db=pBt->db)!=0 && (pDb=db->aDb)!=0 ){
+          while( pDb->pBt==0 || pDb->pBt->pBt!=pBt ){ pDb++; }
+          if( pDb->bSyncSet==0
+           && pDb->safety_level==SQLITE_DEFAULT_SYNCHRONOUS+1
+          ){
+            pDb->safety_level = SQLITE_DEFAULT_WAL_SYNCHRONOUS+1;
+            sqlite3PagerSetFlags(pBt->pPager,
+               pDb->safety_level | (db->flags & PAGER_FLAGS_MASK));
+          }
+        }
+#endif
+        if( isOpen==0 ){
+          releasePage(pPage1);
+          return SQLITE_OK;
+        }
+      }
+      rc = SQLITE_NOTADB;
+    }
+#endif
+
+    /* EVIDENCE-OF: R-15465-20813 The maximum and minimum embedded payload
+    ** fractions and the leaf payload fraction values must be 64, 32, and 32.
+    **
+    ** The original design allowed these amounts to vary, but as of
+    ** version 3.6.0, we require them to be fixed.
+    */
+    if( memcmp(&page1[21], "\100\040\040",3)!=0 ){
+      goto page1_init_failed;
+    }
+    /* EVIDENCE-OF: R-51873-39618 The page size for a database file is
+    ** determined by the 2-byte integer located at an offset of 16 bytes from
+    ** the beginning of the database file. */
+    pageSize = (page1[16]<<8) | (page1[17]<<16);
+    /* EVIDENCE-OF: R-25008-21688 The size of a page is a power of two
+    ** between 512 and 65536 inclusive. */
+    if( ((pageSize-1)&pageSize)!=0
+     || pageSize>SQLITE_MAX_PAGE_SIZE 
+     || pageSize<=256 
+    ){
+      goto page1_init_failed;
+    }
+    assert( (pageSize & 7)==0 );
+    /* EVIDENCE-OF: R-59310-51205 The "reserved space" size in the 1-byte
+    ** integer at offset 20 is the number of bytes of space at the end of
+    ** each page to reserve for extensions. 
+    **
+    ** EVIDENCE-OF: R-37497-42412 The size of the reserved region is
+    ** determined by the one-byte unsigned integer found at an offset of 20
+    ** into the database file header. */
+    usableSize = pageSize - page1[20];
+    if( (u32)pageSize!=pBt->pageSize ){
+      /* After reading the first page of the database assuming a page size
+      ** of BtShared.pageSize, we have discovered that the page-size is
+      ** actually pageSize. Unlock the database, leave pBt->pPage1 at
+      ** zero and return SQLITE_OK. The caller will call this function
+      ** again with the correct page-size.
+      */
+      releasePage(pPage1);
+      pBt->usableSize = usableSize;
+      pBt->pageSize = pageSize;
+      freeTempSpace(pBt);
+      rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize,
+                                   pageSize-usableSize);
+      return rc;
+    }
+    if( (pBt->db->flags & SQLITE_RecoveryMode)==0 && nPage>nPageFile ){
+      rc = SQLITE_CORRUPT_BKPT;
+      goto page1_init_failed;
+    }
+    /* EVIDENCE-OF: R-28312-64704 However, the usable size is not allowed to
+    ** be less than 480. In other words, if the page size is 512, then the
+    ** reserved space size cannot exceed 32. */
+    if( usableSize<480 ){
+      goto page1_init_failed;
+    }
+    pBt->pageSize = pageSize;
+    pBt->usableSize = usableSize;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    pBt->autoVacuum = (get4byte(&page1[36 + 4*4])?1:0);
+    pBt->incrVacuum = (get4byte(&page1[36 + 7*4])?1:0);
+#endif
+  }
+
+  /* maxLocal is the maximum amount of payload to store locally for
+  ** a cell.  Make sure it is small enough so that at least minFanout
+  ** cells can will fit on one page.  We assume a 10-byte page header.
+  ** Besides the payload, the cell must store:
+  **     2-byte pointer to the cell
+  **     4-byte child pointer
+  **     9-byte nKey value
+  **     4-byte nData value
+  **     4-byte overflow page pointer
+  ** So a cell consists of a 2-byte pointer, a header which is as much as
+  ** 17 bytes long, 0 to N bytes of payload, and an optional 4 byte overflow
+  ** page pointer.
+  */
+  pBt->maxLocal = (u16)((pBt->usableSize-12)*64/255 - 23);
+  pBt->minLocal = (u16)((pBt->usableSize-12)*32/255 - 23);
+  pBt->maxLeaf = (u16)(pBt->usableSize - 35);
+  pBt->minLeaf = (u16)((pBt->usableSize-12)*32/255 - 23);
+  if( pBt->maxLocal>127 ){
+    pBt->max1bytePayload = 127;
+  }else{
+    pBt->max1bytePayload = (u8)pBt->maxLocal;
+  }
+  assert( pBt->maxLeaf + 23 <= MX_CELL_SIZE(pBt) );
+  pBt->pPage1 = pPage1;
+  pBt->nPage = nPage;
+  return SQLITE_OK;
+
+page1_init_failed:
+  releasePage(pPage1);
+  pBt->pPage1 = 0;
+  return rc;
+}
+
+#ifndef NDEBUG
+/*
+** Return the number of cursors open on pBt. This is for use
+** in assert() expressions, so it is only compiled if NDEBUG is not
+** defined.
+**
+** Only write cursors are counted if wrOnly is true.  If wrOnly is
+** false then all cursors are counted.
+**
+** For the purposes of this routine, a cursor is any cursor that
+** is capable of reading or writing to the database.  Cursors that
+** have been tripped into the CURSOR_FAULT state are not counted.
+*/
+static int countValidCursors(BtShared *pBt, int wrOnly){
+  BtCursor *pCur;
+  int r = 0;
+  for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){
+    if( (wrOnly==0 || (pCur->curFlags & BTCF_WriteFlag)!=0)
+     && pCur->eState!=CURSOR_FAULT ) r++; 
+  }
+  return r;
+}
+#endif
+
+/*
+** If there are no outstanding cursors and we are not in the middle
+** of a transaction but there is a read lock on the database, then
+** this routine unrefs the first page of the database file which 
+** has the effect of releasing the read lock.
+**
+** If there is a transaction in progress, this routine is a no-op.
+*/
+static void unlockBtreeIfUnused(BtShared *pBt){
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( countValidCursors(pBt,0)==0 || pBt->inTransaction>TRANS_NONE );
+  if( pBt->inTransaction==TRANS_NONE && pBt->pPage1!=0 ){
+    MemPage *pPage1 = pBt->pPage1;
+    assert( pPage1->aData );
+    assert( sqlite3PagerRefcount(pBt->pPager)==1 );
+    pBt->pPage1 = 0;
+    releasePageNotNull(pPage1);
+  }
+}
+
+/*
+** If pBt points to an empty file then convert that empty file
+** into a new empty database by initializing the first page of
+** the database.
+*/
+static int newDatabase(BtShared *pBt){
+  MemPage *pP1;
+  unsigned char *data;
+  int rc;
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  if( pBt->nPage>0 ){
+    return SQLITE_OK;
+  }
+  pP1 = pBt->pPage1;
+  assert( pP1!=0 );
+  data = pP1->aData;
+  rc = sqlite3PagerWrite(pP1->pDbPage);
+  if( rc ) return rc;
+  memcpy(data, zMagicHeader, sizeof(zMagicHeader));
+  assert( sizeof(zMagicHeader)==16 );
+  data[16] = (u8)((pBt->pageSize>>8)&0xff);
+  data[17] = (u8)((pBt->pageSize>>16)&0xff);
+  data[18] = 1;
+  data[19] = 1;
+  assert( pBt->usableSize<=pBt->pageSize && pBt->usableSize+255>=pBt->pageSize);
+  data[20] = (u8)(pBt->pageSize - pBt->usableSize);
+  data[21] = 64;
+  data[22] = 32;
+  data[23] = 32;
+  memset(&data[24], 0, 100-24);
+  zeroPage(pP1, PTF_INTKEY|PTF_LEAF|PTF_LEAFDATA );
+  pBt->btsFlags |= BTS_PAGESIZE_FIXED;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+  assert( pBt->autoVacuum==1 || pBt->autoVacuum==0 );
+  assert( pBt->incrVacuum==1 || pBt->incrVacuum==0 );
+  put4byte(&data[36 + 4*4], pBt->autoVacuum);
+  put4byte(&data[36 + 7*4], pBt->incrVacuum);
+#endif
+  pBt->nPage = 1;
+  data[31] = 1;
+  return SQLITE_OK;
+}
+
+/*
+** Initialize the first page of the database file (creating a database
+** consisting of a single page and no schema objects). Return SQLITE_OK
+** if successful, or an SQLite error code otherwise.
+*/
+SQLITE_PRIVATE int sqlite3BtreeNewDb(Btree *p){
+  int rc;
+  sqlite3BtreeEnter(p);
+  p->pBt->nPage = 0;
+  rc = newDatabase(p->pBt);
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+/*
+** Attempt to start a new transaction. A write-transaction
+** is started if the second argument is nonzero, otherwise a read-
+** transaction.  If the second argument is 2 or more and exclusive
+** transaction is started, meaning that no other process is allowed
+** to access the database.  A preexisting transaction may not be
+** upgraded to exclusive by calling this routine a second time - the
+** exclusivity flag only works for a new transaction.
+**
+** A write-transaction must be started before attempting any 
+** changes to the database.  None of the following routines 
+** will work unless a transaction is started first:
+**
+**      sqlite3BtreeCreateTable()
+**      sqlite3BtreeCreateIndex()
+**      sqlite3BtreeClearTable()
+**      sqlite3BtreeDropTable()
+**      sqlite3BtreeInsert()
+**      sqlite3BtreeDelete()
+**      sqlite3BtreeUpdateMeta()
+**
+** If an initial attempt to acquire the lock fails because of lock contention
+** and the database was previously unlocked, then invoke the busy handler
+** if there is one.  But if there was previously a read-lock, do not
+** invoke the busy handler - just return SQLITE_BUSY.  SQLITE_BUSY is 
+** returned when there is already a read-lock in order to avoid a deadlock.
+**
+** Suppose there are two processes A and B.  A has a read lock and B has
+** a reserved lock.  B tries to promote to exclusive but is blocked because
+** of A's read lock.  A tries to promote to reserved but is blocked by B.
+** One or the other of the two processes must give way or there can be
+** no progress.  By returning SQLITE_BUSY and not invoking the busy callback
+** when A already has a read lock, we encourage A to give up and let B
+** proceed.
+*/
+SQLITE_PRIVATE int sqlite3BtreeBeginTrans(Btree *p, int wrflag){
+  BtShared *pBt = p->pBt;
+  int rc = SQLITE_OK;
+
+  sqlite3BtreeEnter(p);
+  btreeIntegrity(p);
+
+  /* If the btree is already in a write-transaction, or it
+  ** is already in a read-transaction and a read-transaction
+  ** is requested, this is a no-op.
+  */
+  if( p->inTrans==TRANS_WRITE || (p->inTrans==TRANS_READ && !wrflag) ){
+    goto trans_begun;
+  }
+  assert( pBt->inTransaction==TRANS_WRITE || IfNotOmitAV(pBt->bDoTruncate)==0 );
+
+  /* Write transactions are not possible on a read-only database */
+  if( (pBt->btsFlags & BTS_READ_ONLY)!=0 && wrflag ){
+    rc = SQLITE_READONLY;
+    goto trans_begun;
+  }
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+  {
+    sqlite3 *pBlock = 0;
+    /* If another database handle has already opened a write transaction 
+    ** on this shared-btree structure and a second write transaction is
+    ** requested, return SQLITE_LOCKED.
+    */
+    if( (wrflag && pBt->inTransaction==TRANS_WRITE)
+     || (pBt->btsFlags & BTS_PENDING)!=0
+    ){
+      pBlock = pBt->pWriter->db;
+    }else if( wrflag>1 ){
+      BtLock *pIter;
+      for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
+        if( pIter->pBtree!=p ){
+          pBlock = pIter->pBtree->db;
+          break;
+        }
+      }
+    }
+    if( pBlock ){
+      sqlite3ConnectionBlocked(p->db, pBlock);
+      rc = SQLITE_LOCKED_SHAREDCACHE;
+      goto trans_begun;
+    }
+  }
+#endif
+
+  /* Any read-only or read-write transaction implies a read-lock on 
+  ** page 1. So if some other shared-cache client already has a write-lock 
+  ** on page 1, the transaction cannot be opened. */
+  rc = querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK);
+  if( SQLITE_OK!=rc ) goto trans_begun;
+
+  pBt->btsFlags &= ~BTS_INITIALLY_EMPTY;
+  if( pBt->nPage==0 ) pBt->btsFlags |= BTS_INITIALLY_EMPTY;
+  do {
+    /* Call lockBtree() until either pBt->pPage1 is populated or
+    ** lockBtree() returns something other than SQLITE_OK. lockBtree()
+    ** may return SQLITE_OK but leave pBt->pPage1 set to 0 if after
+    ** reading page 1 it discovers that the page-size of the database 
+    ** file is not pBt->pageSize. In this case lockBtree() will update
+    ** pBt->pageSize to the page-size of the file on disk.
+    */
+    while( pBt->pPage1==0 && SQLITE_OK==(rc = lockBtree(pBt)) );
+
+    if( rc==SQLITE_OK && wrflag ){
+      if( (pBt->btsFlags & BTS_READ_ONLY)!=0 ){
+        rc = SQLITE_READONLY;
+      }else{
+        rc = sqlite3PagerBegin(pBt->pPager,wrflag>1,sqlite3TempInMemory(p->db));
+        if( rc==SQLITE_OK ){
+          rc = newDatabase(pBt);
+        }
+      }
+    }
+  
+    if( rc!=SQLITE_OK ){
+      unlockBtreeIfUnused(pBt);
+    }
+  }while( (rc&0xFF)==SQLITE_BUSY && pBt->inTransaction==TRANS_NONE &&
+          btreeInvokeBusyHandler(pBt) );
+
+  if( rc==SQLITE_OK ){
+    if( p->inTrans==TRANS_NONE ){
+      pBt->nTransaction++;
+#ifndef SQLITE_OMIT_SHARED_CACHE
+      if( p->sharable ){
+        assert( p->lock.pBtree==p && p->lock.iTable==1 );
+        p->lock.eLock = READ_LOCK;
+        p->lock.pNext = pBt->pLock;
+        pBt->pLock = &p->lock;
+      }
+#endif
+    }
+    p->inTrans = (wrflag?TRANS_WRITE:TRANS_READ);
+    if( p->inTrans>pBt->inTransaction ){
+      pBt->inTransaction = p->inTrans;
+    }
+    if( wrflag ){
+      MemPage *pPage1 = pBt->pPage1;
+#ifndef SQLITE_OMIT_SHARED_CACHE
+      assert( !pBt->pWriter );
+      pBt->pWriter = p;
+      pBt->btsFlags &= ~BTS_EXCLUSIVE;
+      if( wrflag>1 ) pBt->btsFlags |= BTS_EXCLUSIVE;
+#endif
+
+      /* If the db-size header field is incorrect (as it may be if an old
+      ** client has been writing the database file), update it now. Doing
+      ** this sooner rather than later means the database size can safely 
+      ** re-read the database size from page 1 if a savepoint or transaction
+      ** rollback occurs within the transaction.
+      */
+      if( pBt->nPage!=get4byte(&pPage1->aData[28]) ){
+        rc = sqlite3PagerWrite(pPage1->pDbPage);
+        if( rc==SQLITE_OK ){
+          put4byte(&pPage1->aData[28], pBt->nPage);
+        }
+      }
+    }
+  }
+
+
+trans_begun:
+  if( rc==SQLITE_OK && wrflag ){
+    /* This call makes sure that the pager has the correct number of
+    ** open savepoints. If the second parameter is greater than 0 and
+    ** the sub-journal is not already open, then it will be opened here.
+    */
+    rc = sqlite3PagerOpenSavepoint(pBt->pPager, p->db->nSavepoint);
+  }
+
+  btreeIntegrity(p);
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+
+/*
+** Set the pointer-map entries for all children of page pPage. Also, if
+** pPage contains cells that point to overflow pages, set the pointer
+** map entries for the overflow pages as well.
+*/
+static int setChildPtrmaps(MemPage *pPage){
+  int i;                             /* Counter variable */
+  int nCell;                         /* Number of cells in page pPage */
+  int rc;                            /* Return code */
+  BtShared *pBt = pPage->pBt;
+  u8 isInitOrig = pPage->isInit;
+  Pgno pgno = pPage->pgno;
+
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  rc = btreeInitPage(pPage);
+  if( rc!=SQLITE_OK ){
+    goto set_child_ptrmaps_out;
+  }
+  nCell = pPage->nCell;
+
+  for(i=0; i<nCell; i++){
+    u8 *pCell = findCell(pPage, i);
+
+    ptrmapPutOvflPtr(pPage, pCell, &rc);
+
+    if( !pPage->leaf ){
+      Pgno childPgno = get4byte(pCell);
+      ptrmapPut(pBt, childPgno, PTRMAP_BTREE, pgno, &rc);
+    }
+  }
+
+  if( !pPage->leaf ){
+    Pgno childPgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
+    ptrmapPut(pBt, childPgno, PTRMAP_BTREE, pgno, &rc);
+  }
+
+set_child_ptrmaps_out:
+  pPage->isInit = isInitOrig;
+  return rc;
+}
+
+/*
+** Somewhere on pPage is a pointer to page iFrom.  Modify this pointer so
+** that it points to iTo. Parameter eType describes the type of pointer to
+** be modified, as  follows:
+**
+** PTRMAP_BTREE:     pPage is a btree-page. The pointer points at a child 
+**                   page of pPage.
+**
+** PTRMAP_OVERFLOW1: pPage is a btree-page. The pointer points at an overflow
+**                   page pointed to by one of the cells on pPage.
+**
+** PTRMAP_OVERFLOW2: pPage is an overflow-page. The pointer points at the next
+**                   overflow page in the list.
+*/
+static int modifyPagePointer(MemPage *pPage, Pgno iFrom, Pgno iTo, u8 eType){
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+  if( eType==PTRMAP_OVERFLOW2 ){
+    /* The pointer is always the first 4 bytes of the page in this case.  */
+    if( get4byte(pPage->aData)!=iFrom ){
+      return SQLITE_CORRUPT_BKPT;
+    }
+    put4byte(pPage->aData, iTo);
+  }else{
+    u8 isInitOrig = pPage->isInit;
+    int i;
+    int nCell;
+    int rc;
+
+    rc = btreeInitPage(pPage);
+    if( rc ) return rc;
+    nCell = pPage->nCell;
+
+    for(i=0; i<nCell; i++){
+      u8 *pCell = findCell(pPage, i);
+      if( eType==PTRMAP_OVERFLOW1 ){
+        CellInfo info;
+        pPage->xParseCell(pPage, pCell, &info);
+        if( info.nLocal<info.nPayload
+         && pCell+info.nSize-1<=pPage->aData+pPage->maskPage
+         && iFrom==get4byte(pCell+info.nSize-4)
+        ){
+          put4byte(pCell+info.nSize-4, iTo);
+          break;
+        }
+      }else{
+        if( get4byte(pCell)==iFrom ){
+          put4byte(pCell, iTo);
+          break;
+        }
+      }
+    }
+  
+    if( i==nCell ){
+      if( eType!=PTRMAP_BTREE || 
+          get4byte(&pPage->aData[pPage->hdrOffset+8])!=iFrom ){
+        return SQLITE_CORRUPT_BKPT;
+      }
+      put4byte(&pPage->aData[pPage->hdrOffset+8], iTo);
+    }
+
+    pPage->isInit = isInitOrig;
+  }
+  return SQLITE_OK;
+}
+
+
+/*
+** Move the open database page pDbPage to location iFreePage in the 
+** database. The pDbPage reference remains valid.
+**
+** The isCommit flag indicates that there is no need to remember that
+** the journal needs to be sync()ed before database page pDbPage->pgno 
+** can be written to. The caller has already promised not to write to that
+** page.
+*/
+static int relocatePage(
+  BtShared *pBt,           /* Btree */
+  MemPage *pDbPage,        /* Open page to move */
+  u8 eType,                /* Pointer map 'type' entry for pDbPage */
+  Pgno iPtrPage,           /* Pointer map 'page-no' entry for pDbPage */
+  Pgno iFreePage,          /* The location to move pDbPage to */
+  int isCommit             /* isCommit flag passed to sqlite3PagerMovepage */
+){
+  MemPage *pPtrPage;   /* The page that contains a pointer to pDbPage */
+  Pgno iDbPage = pDbPage->pgno;
+  Pager *pPager = pBt->pPager;
+  int rc;
+
+  assert( eType==PTRMAP_OVERFLOW2 || eType==PTRMAP_OVERFLOW1 || 
+      eType==PTRMAP_BTREE || eType==PTRMAP_ROOTPAGE );
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( pDbPage->pBt==pBt );
+
+  /* Move page iDbPage from its current location to page number iFreePage */
+  TRACE(("AUTOVACUUM: Moving %d to free page %d (ptr page %d type %d)\n", 
+      iDbPage, iFreePage, iPtrPage, eType));
+  rc = sqlite3PagerMovepage(pPager, pDbPage->pDbPage, iFreePage, isCommit);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+  pDbPage->pgno = iFreePage;
+
+  /* If pDbPage was a btree-page, then it may have child pages and/or cells
+  ** that point to overflow pages. The pointer map entries for all these
+  ** pages need to be changed.
+  **
+  ** If pDbPage is an overflow page, then the first 4 bytes may store a
+  ** pointer to a subsequent overflow page. If this is the case, then
+  ** the pointer map needs to be updated for the subsequent overflow page.
+  */
+  if( eType==PTRMAP_BTREE || eType==PTRMAP_ROOTPAGE ){
+    rc = setChildPtrmaps(pDbPage);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+  }else{
+    Pgno nextOvfl = get4byte(pDbPage->aData);
+    if( nextOvfl!=0 ){
+      ptrmapPut(pBt, nextOvfl, PTRMAP_OVERFLOW2, iFreePage, &rc);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+    }
+  }
+
+  /* Fix the database pointer on page iPtrPage that pointed at iDbPage so
+  ** that it points at iFreePage. Also fix the pointer map entry for
+  ** iPtrPage.
+  */
+  if( eType!=PTRMAP_ROOTPAGE ){
+    rc = btreeGetPage(pBt, iPtrPage, &pPtrPage, 0);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    rc = sqlite3PagerWrite(pPtrPage->pDbPage);
+    if( rc!=SQLITE_OK ){
+      releasePage(pPtrPage);
+      return rc;
+    }
+    rc = modifyPagePointer(pPtrPage, iDbPage, iFreePage, eType);
+    releasePage(pPtrPage);
+    if( rc==SQLITE_OK ){
+      ptrmapPut(pBt, iFreePage, eType, iPtrPage, &rc);
+    }
+  }
+  return rc;
+}
+
+/* Forward declaration required by incrVacuumStep(). */
+static int allocateBtreePage(BtShared *, MemPage **, Pgno *, Pgno, u8);
+
+/*
+** Perform a single step of an incremental-vacuum. If successful, return
+** SQLITE_OK. If there is no work to do (and therefore no point in 
+** calling this function again), return SQLITE_DONE. Or, if an error 
+** occurs, return some other error code.
+**
+** More specifically, this function attempts to re-organize the database so 
+** that the last page of the file currently in use is no longer in use.
+**
+** Parameter nFin is the number of pages that this database would contain
+** were this function called until it returns SQLITE_DONE.
+**
+** If the bCommit parameter is non-zero, this function assumes that the 
+** caller will keep calling incrVacuumStep() until it returns SQLITE_DONE 
+** or an error. bCommit is passed true for an auto-vacuum-on-commit 
+** operation, or false for an incremental vacuum.
+*/
+static int incrVacuumStep(BtShared *pBt, Pgno nFin, Pgno iLastPg, int bCommit){
+  Pgno nFreeList;           /* Number of pages still on the free-list */
+  int rc;
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( iLastPg>nFin );
+
+  if( !PTRMAP_ISPAGE(pBt, iLastPg) && iLastPg!=PENDING_BYTE_PAGE(pBt) ){
+    u8 eType;
+    Pgno iPtrPage;
+
+    nFreeList = get4byte(&pBt->pPage1->aData[36]);
+    if( nFreeList==0 ){
+      return SQLITE_DONE;
+    }
+
+    rc = ptrmapGet(pBt, iLastPg, &eType, &iPtrPage);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    if( eType==PTRMAP_ROOTPAGE ){
+      return SQLITE_CORRUPT_BKPT;
+    }
+
+    if( eType==PTRMAP_FREEPAGE ){
+      if( bCommit==0 ){
+        /* Remove the page from the files free-list. This is not required
+        ** if bCommit is non-zero. In that case, the free-list will be
+        ** truncated to zero after this function returns, so it doesn't 
+        ** matter if it still contains some garbage entries.
+        */
+        Pgno iFreePg;
+        MemPage *pFreePg;
+        rc = allocateBtreePage(pBt, &pFreePg, &iFreePg, iLastPg, BTALLOC_EXACT);
+        if( rc!=SQLITE_OK ){
+          return rc;
+        }
+        assert( iFreePg==iLastPg );
+        releasePage(pFreePg);
+      }
+    } else {
+      Pgno iFreePg;             /* Index of free page to move pLastPg to */
+      MemPage *pLastPg;
+      u8 eMode = BTALLOC_ANY;   /* Mode parameter for allocateBtreePage() */
+      Pgno iNear = 0;           /* nearby parameter for allocateBtreePage() */
+
+      rc = btreeGetPage(pBt, iLastPg, &pLastPg, 0);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+
+      /* If bCommit is zero, this loop runs exactly once and page pLastPg
+      ** is swapped with the first free page pulled off the free list.
+      **
+      ** On the other hand, if bCommit is greater than zero, then keep
+      ** looping until a free-page located within the first nFin pages
+      ** of the file is found.
+      */
+      if( bCommit==0 ){
+        eMode = BTALLOC_LE;
+        iNear = nFin;
+      }
+      do {
+        MemPage *pFreePg;
+        rc = allocateBtreePage(pBt, &pFreePg, &iFreePg, iNear, eMode);
+        if( rc!=SQLITE_OK ){
+          releasePage(pLastPg);
+          return rc;
+        }
+        releasePage(pFreePg);
+      }while( bCommit && iFreePg>nFin );
+      assert( iFreePg<iLastPg );
+      
+      rc = relocatePage(pBt, pLastPg, eType, iPtrPage, iFreePg, bCommit);
+      releasePage(pLastPg);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+    }
+  }
+
+  if( bCommit==0 ){
+    do {
+      iLastPg--;
+    }while( iLastPg==PENDING_BYTE_PAGE(pBt) || PTRMAP_ISPAGE(pBt, iLastPg) );
+    pBt->bDoTruncate = 1;
+    pBt->nPage = iLastPg;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** The database opened by the first argument is an auto-vacuum database
+** nOrig pages in size containing nFree free pages. Return the expected 
+** size of the database in pages following an auto-vacuum operation.
+*/
+static Pgno finalDbSize(BtShared *pBt, Pgno nOrig, Pgno nFree){
+  int nEntry;                     /* Number of entries on one ptrmap page */
+  Pgno nPtrmap;                   /* Number of PtrMap pages to be freed */
+  Pgno nFin;                      /* Return value */
+
+  nEntry = pBt->usableSize/5;
+  nPtrmap = (nFree-nOrig+PTRMAP_PAGENO(pBt, nOrig)+nEntry)/nEntry;
+  nFin = nOrig - nFree - nPtrmap;
+  if( nOrig>PENDING_BYTE_PAGE(pBt) && nFin<PENDING_BYTE_PAGE(pBt) ){
+    nFin--;
+  }
+  while( PTRMAP_ISPAGE(pBt, nFin) || nFin==PENDING_BYTE_PAGE(pBt) ){
+    nFin--;
+  }
+
+  return nFin;
+}
+
+/*
+** A write-transaction must be opened before calling this function.
+** It performs a single unit of work towards an incremental vacuum.
+**
+** If the incremental vacuum is finished after this function has run,
+** SQLITE_DONE is returned. If it is not finished, but no error occurred,
+** SQLITE_OK is returned. Otherwise an SQLite error code. 
+*/
+SQLITE_PRIVATE int sqlite3BtreeIncrVacuum(Btree *p){
+  int rc;
+  BtShared *pBt = p->pBt;
+
+  sqlite3BtreeEnter(p);
+  assert( pBt->inTransaction==TRANS_WRITE && p->inTrans==TRANS_WRITE );
+  if( !pBt->autoVacuum ){
+    rc = SQLITE_DONE;
+  }else{
+    Pgno nOrig = btreePagecount(pBt);
+    Pgno nFree = get4byte(&pBt->pPage1->aData[36]);
+    Pgno nFin = finalDbSize(pBt, nOrig, nFree);
+
+    if( nOrig<nFin ){
+      rc = SQLITE_CORRUPT_BKPT;
+    }else if( nFree>0 ){
+      rc = saveAllCursors(pBt, 0, 0);
+      if( rc==SQLITE_OK ){
+        invalidateAllOverflowCache(pBt);
+        rc = incrVacuumStep(pBt, nFin, nOrig, 0);
+      }
+      if( rc==SQLITE_OK ){
+        rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
+        put4byte(&pBt->pPage1->aData[28], pBt->nPage);
+      }
+    }else{
+      rc = SQLITE_DONE;
+    }
+  }
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+/*
+** This routine is called prior to sqlite3PagerCommit when a transaction
+** is committed for an auto-vacuum database.
+**
+** If SQLITE_OK is returned, then *pnTrunc is set to the number of pages
+** the database file should be truncated to during the commit process. 
+** i.e. the database has been reorganized so that only the first *pnTrunc
+** pages are in use.
+*/
+static int autoVacuumCommit(BtShared *pBt){
+  int rc = SQLITE_OK;
+  Pager *pPager = pBt->pPager;
+  VVA_ONLY( int nRef = sqlite3PagerRefcount(pPager); )
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  invalidateAllOverflowCache(pBt);
+  assert(pBt->autoVacuum);
+  if( !pBt->incrVacuum ){
+    Pgno nFin;         /* Number of pages in database after autovacuuming */
+    Pgno nFree;        /* Number of pages on the freelist initially */
+    Pgno iFree;        /* The next page to be freed */
+    Pgno nOrig;        /* Database size before freeing */
+
+    nOrig = btreePagecount(pBt);
+    if( PTRMAP_ISPAGE(pBt, nOrig) || nOrig==PENDING_BYTE_PAGE(pBt) ){
+      /* It is not possible to create a database for which the final page
+      ** is either a pointer-map page or the pending-byte page. If one
+      ** is encountered, this indicates corruption.
+      */
+      return SQLITE_CORRUPT_BKPT;
+    }
+
+    nFree = get4byte(&pBt->pPage1->aData[36]);
+    nFin = finalDbSize(pBt, nOrig, nFree);
+    if( nFin>nOrig ) return SQLITE_CORRUPT_BKPT;
+    if( nFin<nOrig ){
+      rc = saveAllCursors(pBt, 0, 0);
+    }
+    for(iFree=nOrig; iFree>nFin && rc==SQLITE_OK; iFree--){
+      rc = incrVacuumStep(pBt, nFin, iFree, 1);
+    }
+    if( (rc==SQLITE_DONE || rc==SQLITE_OK) && nFree>0 ){
+      rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
+      put4byte(&pBt->pPage1->aData[32], 0);
+      put4byte(&pBt->pPage1->aData[36], 0);
+      put4byte(&pBt->pPage1->aData[28], nFin);
+      pBt->bDoTruncate = 1;
+      pBt->nPage = nFin;
+    }
+    if( rc!=SQLITE_OK ){
+      sqlite3PagerRollback(pPager);
+    }
+  }
+
+  assert( nRef>=sqlite3PagerRefcount(pPager) );
+  return rc;
+}
+
+#else /* ifndef SQLITE_OMIT_AUTOVACUUM */
+# define setChildPtrmaps(x) SQLITE_OK
+#endif
+
+/*
+** This routine does the first phase of a two-phase commit.  This routine
+** causes a rollback journal to be created (if it does not already exist)
+** and populated with enough information so that if a power loss occurs
+** the database can be restored to its original state by playing back
+** the journal.  Then the contents of the journal are flushed out to
+** the disk.  After the journal is safely on oxide, the changes to the
+** database are written into the database file and flushed to oxide.
+** At the end of this call, the rollback journal still exists on the
+** disk and we are still holding all locks, so the transaction has not
+** committed.  See sqlite3BtreeCommitPhaseTwo() for the second phase of the
+** commit process.
+**
+** This call is a no-op if no write-transaction is currently active on pBt.
+**
+** Otherwise, sync the database file for the btree pBt. zMaster points to
+** the name of a master journal file that should be written into the
+** individual journal file, or is NULL, indicating no master journal file 
+** (single database transaction).
+**
+** When this is called, the master journal should already have been
+** created, populated with this journal pointer and synced to disk.
+**
+** Once this is routine has returned, the only thing required to commit
+** the write-transaction for this database file is to delete the journal.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCommitPhaseOne(Btree *p, const char *zMaster){
+  int rc = SQLITE_OK;
+  if( p->inTrans==TRANS_WRITE ){
+    BtShared *pBt = p->pBt;
+    sqlite3BtreeEnter(p);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    if( pBt->autoVacuum ){
+      rc = autoVacuumCommit(pBt);
+      if( rc!=SQLITE_OK ){
+        sqlite3BtreeLeave(p);
+        return rc;
+      }
+    }
+    if( pBt->bDoTruncate ){
+      sqlite3PagerTruncateImage(pBt->pPager, pBt->nPage);
+    }
+#endif
+    rc = sqlite3PagerCommitPhaseOne(pBt->pPager, zMaster, 0);
+    sqlite3BtreeLeave(p);
+  }
+  return rc;
+}
+
+/*
+** This function is called from both BtreeCommitPhaseTwo() and BtreeRollback()
+** at the conclusion of a transaction.
+*/
+static void btreeEndTransaction(Btree *p){
+  BtShared *pBt = p->pBt;
+  sqlite3 *db = p->db;
+  assert( sqlite3BtreeHoldsMutex(p) );
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+  pBt->bDoTruncate = 0;
+#endif
+  if( p->inTrans>TRANS_NONE && db->nVdbeRead>1 ){
+    /* If there are other active statements that belong to this database
+    ** handle, downgrade to a read-only transaction. The other statements
+    ** may still be reading from the database.  */
+    downgradeAllSharedCacheTableLocks(p);
+    p->inTrans = TRANS_READ;
+  }else{
+    /* If the handle had any kind of transaction open, decrement the 
+    ** transaction count of the shared btree. If the transaction count 
+    ** reaches 0, set the shared state to TRANS_NONE. The unlockBtreeIfUnused()
+    ** call below will unlock the pager.  */
+    if( p->inTrans!=TRANS_NONE ){
+      clearAllSharedCacheTableLocks(p);
+      pBt->nTransaction--;
+      if( 0==pBt->nTransaction ){
+        pBt->inTransaction = TRANS_NONE;
+      }
+    }
+
+    /* Set the current transaction state to TRANS_NONE and unlock the 
+    ** pager if this call closed the only read or write transaction.  */
+    p->inTrans = TRANS_NONE;
+    unlockBtreeIfUnused(pBt);
+  }
+
+  btreeIntegrity(p);
+}
+
+/*
+** Commit the transaction currently in progress.
+**
+** This routine implements the second phase of a 2-phase commit.  The
+** sqlite3BtreeCommitPhaseOne() routine does the first phase and should
+** be invoked prior to calling this routine.  The sqlite3BtreeCommitPhaseOne()
+** routine did all the work of writing information out to disk and flushing the
+** contents so that they are written onto the disk platter.  All this
+** routine has to do is delete or truncate or zero the header in the
+** the rollback journal (which causes the transaction to commit) and
+** drop locks.
+**
+** Normally, if an error occurs while the pager layer is attempting to 
+** finalize the underlying journal file, this function returns an error and
+** the upper layer will attempt a rollback. However, if the second argument
+** is non-zero then this b-tree transaction is part of a multi-file 
+** transaction. In this case, the transaction has already been committed 
+** (by deleting a master journal file) and the caller will ignore this 
+** functions return code. So, even if an error occurs in the pager layer,
+** reset the b-tree objects internal state to indicate that the write
+** transaction has been closed. This is quite safe, as the pager will have
+** transitioned to the error state.
+**
+** This will release the write lock on the database file.  If there
+** are no active cursors, it also releases the read lock.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCommitPhaseTwo(Btree *p, int bCleanup){
+
+  if( p->inTrans==TRANS_NONE ) return SQLITE_OK;
+  sqlite3BtreeEnter(p);
+  btreeIntegrity(p);
+
+  /* If the handle has a write-transaction open, commit the shared-btrees 
+  ** transaction and set the shared state to TRANS_READ.
+  */
+  if( p->inTrans==TRANS_WRITE ){
+    int rc;
+    BtShared *pBt = p->pBt;
+    assert( pBt->inTransaction==TRANS_WRITE );
+    assert( pBt->nTransaction>0 );
+    rc = sqlite3PagerCommitPhaseTwo(pBt->pPager);
+    if( rc!=SQLITE_OK && bCleanup==0 ){
+      sqlite3BtreeLeave(p);
+      return rc;
+    }
+    p->iDataVersion--;  /* Compensate for pPager->iDataVersion++; */
+    pBt->inTransaction = TRANS_READ;
+    btreeClearHasContent(pBt);
+  }
+
+  btreeEndTransaction(p);
+  sqlite3BtreeLeave(p);
+  return SQLITE_OK;
+}
+
+/*
+** Do both phases of a commit.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCommit(Btree *p){
+  int rc;
+  sqlite3BtreeEnter(p);
+  rc = sqlite3BtreeCommitPhaseOne(p, 0);
+  if( rc==SQLITE_OK ){
+    rc = sqlite3BtreeCommitPhaseTwo(p, 0);
+  }
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+/*
+** This routine sets the state to CURSOR_FAULT and the error
+** code to errCode for every cursor on any BtShared that pBtree
+** references.  Or if the writeOnly flag is set to 1, then only
+** trip write cursors and leave read cursors unchanged.
+**
+** Every cursor is a candidate to be tripped, including cursors
+** that belong to other database connections that happen to be
+** sharing the cache with pBtree.
+**
+** This routine gets called when a rollback occurs. If the writeOnly
+** flag is true, then only write-cursors need be tripped - read-only
+** cursors save their current positions so that they may continue 
+** following the rollback. Or, if writeOnly is false, all cursors are 
+** tripped. In general, writeOnly is false if the transaction being
+** rolled back modified the database schema. In this case b-tree root
+** pages may be moved or deleted from the database altogether, making
+** it unsafe for read cursors to continue.
+**
+** If the writeOnly flag is true and an error is encountered while 
+** saving the current position of a read-only cursor, all cursors, 
+** including all read-cursors are tripped.
+**
+** SQLITE_OK is returned if successful, or if an error occurs while
+** saving a cursor position, an SQLite error code.
+*/
+SQLITE_PRIVATE int sqlite3BtreeTripAllCursors(Btree *pBtree, int errCode, int writeOnly){
+  BtCursor *p;
+  int rc = SQLITE_OK;
+
+  assert( (writeOnly==0 || writeOnly==1) && BTCF_WriteFlag==1 );
+  if( pBtree ){
+    sqlite3BtreeEnter(pBtree);
+    for(p=pBtree->pBt->pCursor; p; p=p->pNext){
+      int i;
+      if( writeOnly && (p->curFlags & BTCF_WriteFlag)==0 ){
+        if( p->eState==CURSOR_VALID || p->eState==CURSOR_SKIPNEXT ){
+          rc = saveCursorPosition(p);
+          if( rc!=SQLITE_OK ){
+            (void)sqlite3BtreeTripAllCursors(pBtree, rc, 0);
+            break;
+          }
+        }
+      }else{
+        sqlite3BtreeClearCursor(p);
+        p->eState = CURSOR_FAULT;
+        p->skipNext = errCode;
+      }
+      for(i=0; i<=p->iPage; i++){
+        releasePage(p->apPage[i]);
+        p->apPage[i] = 0;
+      }
+    }
+    sqlite3BtreeLeave(pBtree);
+  }
+  return rc;
+}
+
+/*
+** Rollback the transaction in progress.
+**
+** If tripCode is not SQLITE_OK then cursors will be invalidated (tripped).
+** Only write cursors are tripped if writeOnly is true but all cursors are
+** tripped if writeOnly is false.  Any attempt to use
+** a tripped cursor will result in an error.
+**
+** This will release the write lock on the database file.  If there
+** are no active cursors, it also releases the read lock.
+*/
+SQLITE_PRIVATE int sqlite3BtreeRollback(Btree *p, int tripCode, int writeOnly){
+  int rc;
+  BtShared *pBt = p->pBt;
+  MemPage *pPage1;
+
+  assert( writeOnly==1 || writeOnly==0 );
+  assert( tripCode==SQLITE_ABORT_ROLLBACK || tripCode==SQLITE_OK );
+  sqlite3BtreeEnter(p);
+  if( tripCode==SQLITE_OK ){
+    rc = tripCode = saveAllCursors(pBt, 0, 0);
+    if( rc ) writeOnly = 0;
+  }else{
+    rc = SQLITE_OK;
+  }
+  if( tripCode ){
+    int rc2 = sqlite3BtreeTripAllCursors(p, tripCode, writeOnly);
+    assert( rc==SQLITE_OK || (writeOnly==0 && rc2==SQLITE_OK) );
+    if( rc2!=SQLITE_OK ) rc = rc2;
+  }
+  btreeIntegrity(p);
+
+  if( p->inTrans==TRANS_WRITE ){
+    int rc2;
+
+    assert( TRANS_WRITE==pBt->inTransaction );
+    rc2 = sqlite3PagerRollback(pBt->pPager);
+    if( rc2!=SQLITE_OK ){
+      rc = rc2;
+    }
+
+    /* The rollback may have destroyed the pPage1->aData value.  So
+    ** call btreeGetPage() on page 1 again to make
+    ** sure pPage1->aData is set correctly. */
+    if( btreeGetPage(pBt, 1, &pPage1, 0)==SQLITE_OK ){
+      int nPage = get4byte(28+(u8*)pPage1->aData);
+      testcase( nPage==0 );
+      if( nPage==0 ) sqlite3PagerPagecount(pBt->pPager, &nPage);
+      testcase( pBt->nPage!=nPage );
+      pBt->nPage = nPage;
+      releasePage(pPage1);
+    }
+    assert( countValidCursors(pBt, 1)==0 );
+    pBt->inTransaction = TRANS_READ;
+    btreeClearHasContent(pBt);
+  }
+
+  btreeEndTransaction(p);
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+/*
+** Start a statement subtransaction. The subtransaction can be rolled
+** back independently of the main transaction. You must start a transaction 
+** before starting a subtransaction. The subtransaction is ended automatically 
+** if the main transaction commits or rolls back.
+**
+** Statement subtransactions are used around individual SQL statements
+** that are contained within a BEGIN...COMMIT block.  If a constraint
+** error occurs within the statement, the effect of that one statement
+** can be rolled back without having to rollback the entire transaction.
+**
+** A statement sub-transaction is implemented as an anonymous savepoint. The
+** value passed as the second parameter is the total number of savepoints,
+** including the new anonymous savepoint, open on the B-Tree. i.e. if there
+** are no active savepoints and no other statement-transactions open,
+** iStatement is 1. This anonymous savepoint can be released or rolled back
+** using the sqlite3BtreeSavepoint() function.
+*/
+SQLITE_PRIVATE int sqlite3BtreeBeginStmt(Btree *p, int iStatement){
+  int rc;
+  BtShared *pBt = p->pBt;
+  sqlite3BtreeEnter(p);
+  assert( p->inTrans==TRANS_WRITE );
+  assert( (pBt->btsFlags & BTS_READ_ONLY)==0 );
+  assert( iStatement>0 );
+  assert( iStatement>p->db->nSavepoint );
+  assert( pBt->inTransaction==TRANS_WRITE );
+  /* At the pager level, a statement transaction is a savepoint with
+  ** an index greater than all savepoints created explicitly using
+  ** SQL statements. It is illegal to open, release or rollback any
+  ** such savepoints while the statement transaction savepoint is active.
+  */
+  rc = sqlite3PagerOpenSavepoint(pBt->pPager, iStatement);
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+/*
+** The second argument to this function, op, is always SAVEPOINT_ROLLBACK
+** or SAVEPOINT_RELEASE. This function either releases or rolls back the
+** savepoint identified by parameter iSavepoint, depending on the value 
+** of op.
+**
+** Normally, iSavepoint is greater than or equal to zero. However, if op is
+** SAVEPOINT_ROLLBACK, then iSavepoint may also be -1. In this case the 
+** contents of the entire transaction are rolled back. This is different
+** from a normal transaction rollback, as no locks are released and the
+** transaction remains open.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSavepoint(Btree *p, int op, int iSavepoint){
+  int rc = SQLITE_OK;
+  if( p && p->inTrans==TRANS_WRITE ){
+    BtShared *pBt = p->pBt;
+    assert( op==SAVEPOINT_RELEASE || op==SAVEPOINT_ROLLBACK );
+    assert( iSavepoint>=0 || (iSavepoint==-1 && op==SAVEPOINT_ROLLBACK) );
+    sqlite3BtreeEnter(p);
+    rc = sqlite3PagerSavepoint(pBt->pPager, op, iSavepoint);
+    if( rc==SQLITE_OK ){
+      if( iSavepoint<0 && (pBt->btsFlags & BTS_INITIALLY_EMPTY)!=0 ){
+        pBt->nPage = 0;
+      }
+      rc = newDatabase(pBt);
+      pBt->nPage = get4byte(28 + pBt->pPage1->aData);
+
+      /* The database size was written into the offset 28 of the header
+      ** when the transaction started, so we know that the value at offset
+      ** 28 is nonzero. */
+      assert( pBt->nPage>0 );
+    }
+    sqlite3BtreeLeave(p);
+  }
+  return rc;
+}
+
+/*
+** Create a new cursor for the BTree whose root is on the page
+** iTable. If a read-only cursor is requested, it is assumed that
+** the caller already has at least a read-only transaction open
+** on the database already. If a write-cursor is requested, then
+** the caller is assumed to have an open write transaction.
+**
+** If the BTREE_WRCSR bit of wrFlag is clear, then the cursor can only
+** be used for reading.  If the BTREE_WRCSR bit is set, then the cursor
+** can be used for reading or for writing if other conditions for writing
+** are also met.  These are the conditions that must be met in order
+** for writing to be allowed:
+**
+** 1:  The cursor must have been opened with wrFlag containing BTREE_WRCSR
+**
+** 2:  Other database connections that share the same pager cache
+**     but which are not in the READ_UNCOMMITTED state may not have
+**     cursors open with wrFlag==0 on the same table.  Otherwise
+**     the changes made by this write cursor would be visible to
+**     the read cursors in the other database connection.
+**
+** 3:  The database must be writable (not on read-only media)
+**
+** 4:  There must be an active transaction.
+**
+** The BTREE_FORDELETE bit of wrFlag may optionally be set if BTREE_WRCSR
+** is set.  If FORDELETE is set, that is a hint to the implementation that
+** this cursor will only be used to seek to and delete entries of an index
+** as part of a larger DELETE statement.  The FORDELETE hint is not used by
+** this implementation.  But in a hypothetical alternative storage engine 
+** in which index entries are automatically deleted when corresponding table
+** rows are deleted, the FORDELETE flag is a hint that all SEEK and DELETE
+** operations on this cursor can be no-ops and all READ operations can 
+** return a null row (2-bytes: 0x01 0x00).
+**
+** No checking is done to make sure that page iTable really is the
+** root page of a b-tree.  If it is not, then the cursor acquired
+** will not work correctly.
+**
+** It is assumed that the sqlite3BtreeCursorZero() has been called
+** on pCur to initialize the memory space prior to invoking this routine.
+*/
+static int btreeCursor(
+  Btree *p,                              /* The btree */
+  int iTable,                            /* Root page of table to open */
+  int wrFlag,                            /* 1 to write. 0 read-only */
+  struct KeyInfo *pKeyInfo,              /* First arg to comparison function */
+  BtCursor *pCur                         /* Space for new cursor */
+){
+  BtShared *pBt = p->pBt;                /* Shared b-tree handle */
+  BtCursor *pX;                          /* Looping over other all cursors */
+
+  assert( sqlite3BtreeHoldsMutex(p) );
+  assert( wrFlag==0 
+       || wrFlag==BTREE_WRCSR 
+       || wrFlag==(BTREE_WRCSR|BTREE_FORDELETE) 
+  );
+
+  /* The following assert statements verify that if this is a sharable 
+  ** b-tree database, the connection is holding the required table locks, 
+  ** and that no other connection has any open cursor that conflicts with 
+  ** this lock.  */
+  assert( hasSharedCacheTableLock(p, iTable, pKeyInfo!=0, (wrFlag?2:1)) );
+  assert( wrFlag==0 || !hasReadConflicts(p, iTable) );
+
+  /* Assert that the caller has opened the required transaction. */
+  assert( p->inTrans>TRANS_NONE );
+  assert( wrFlag==0 || p->inTrans==TRANS_WRITE );
+  assert( pBt->pPage1 && pBt->pPage1->aData );
+  assert( wrFlag==0 || (pBt->btsFlags & BTS_READ_ONLY)==0 );
+
+  if( wrFlag ){
+    allocateTempSpace(pBt);
+    if( pBt->pTmpSpace==0 ) return SQLITE_NOMEM_BKPT;
+  }
+  if( iTable==1 && btreePagecount(pBt)==0 ){
+    assert( wrFlag==0 );
+    iTable = 0;
+  }
+
+  /* Now that no other errors can occur, finish filling in the BtCursor
+  ** variables and link the cursor into the BtShared list.  */
+  pCur->pgnoRoot = (Pgno)iTable;
+  pCur->iPage = -1;
+  pCur->pKeyInfo = pKeyInfo;
+  pCur->pBtree = p;
+  pCur->pBt = pBt;
+  pCur->curFlags = wrFlag ? BTCF_WriteFlag : 0;
+  pCur->curPagerFlags = wrFlag ? 0 : PAGER_GET_READONLY;
+  /* If there are two or more cursors on the same btree, then all such
+  ** cursors *must* have the BTCF_Multiple flag set. */
+  for(pX=pBt->pCursor; pX; pX=pX->pNext){
+    if( pX->pgnoRoot==(Pgno)iTable ){
+      pX->curFlags |= BTCF_Multiple;
+      pCur->curFlags |= BTCF_Multiple;
+    }
+  }
+  pCur->pNext = pBt->pCursor;
+  pBt->pCursor = pCur;
+  pCur->eState = CURSOR_INVALID;
+  return SQLITE_OK;
+}
+SQLITE_PRIVATE int sqlite3BtreeCursor(
+  Btree *p,                                   /* The btree */
+  int iTable,                                 /* Root page of table to open */
+  int wrFlag,                                 /* 1 to write. 0 read-only */
+  struct KeyInfo *pKeyInfo,                   /* First arg to xCompare() */
+  BtCursor *pCur                              /* Write new cursor here */
+){
+  int rc;
+  if( iTable<1 ){
+    rc = SQLITE_CORRUPT_BKPT;
+  }else{
+    sqlite3BtreeEnter(p);
+    rc = btreeCursor(p, iTable, wrFlag, pKeyInfo, pCur);
+    sqlite3BtreeLeave(p);
+  }
+  return rc;
+}
+
+/*
+** Return the size of a BtCursor object in bytes.
+**
+** This interfaces is needed so that users of cursors can preallocate
+** sufficient storage to hold a cursor.  The BtCursor object is opaque
+** to users so they cannot do the sizeof() themselves - they must call
+** this routine.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCursorSize(void){
+  return ROUND8(sizeof(BtCursor));
+}
+
+/*
+** Initialize memory that will be converted into a BtCursor object.
+**
+** The simple approach here would be to memset() the entire object
+** to zero.  But it turns out that the apPage[] and aiIdx[] arrays
+** do not need to be zeroed and they are large, so we can save a lot
+** of run-time by skipping the initialization of those elements.
+*/
+SQLITE_PRIVATE void sqlite3BtreeCursorZero(BtCursor *p){
+  memset(p, 0, offsetof(BtCursor, iPage));
+}
+
+/*
+** Close a cursor.  The read lock on the database file is released
+** when the last cursor is closed.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCloseCursor(BtCursor *pCur){
+  Btree *pBtree = pCur->pBtree;
+  if( pBtree ){
+    int i;
+    BtShared *pBt = pCur->pBt;
+    sqlite3BtreeEnter(pBtree);
+    sqlite3BtreeClearCursor(pCur);
+    assert( pBt->pCursor!=0 );
+    if( pBt->pCursor==pCur ){
+      pBt->pCursor = pCur->pNext;
+    }else{
+      BtCursor *pPrev = pBt->pCursor;
+      do{
+        if( pPrev->pNext==pCur ){
+          pPrev->pNext = pCur->pNext;
+          break;
+        }
+        pPrev = pPrev->pNext;
+      }while( ALWAYS(pPrev) );
+    }
+    for(i=0; i<=pCur->iPage; i++){
+      releasePage(pCur->apPage[i]);
+    }
+    unlockBtreeIfUnused(pBt);
+    sqlite3_free(pCur->aOverflow);
+    /* sqlite3_free(pCur); */
+    sqlite3BtreeLeave(pBtree);
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Make sure the BtCursor* given in the argument has a valid
+** BtCursor.info structure.  If it is not already valid, call
+** btreeParseCell() to fill it in.
+**
+** BtCursor.info is a cache of the information in the current cell.
+** Using this cache reduces the number of calls to btreeParseCell().
+*/
+#ifndef NDEBUG
+  static void assertCellInfo(BtCursor *pCur){
+    CellInfo info;
+    int iPage = pCur->iPage;
+    memset(&info, 0, sizeof(info));
+    btreeParseCell(pCur->apPage[iPage], pCur->aiIdx[iPage], &info);
+    assert( CORRUPT_DB || memcmp(&info, &pCur->info, sizeof(info))==0 );
+  }
+#else
+  #define assertCellInfo(x)
+#endif
+static SQLITE_NOINLINE void getCellInfo(BtCursor *pCur){
+  if( pCur->info.nSize==0 ){
+    int iPage = pCur->iPage;
+    pCur->curFlags |= BTCF_ValidNKey;
+    btreeParseCell(pCur->apPage[iPage],pCur->aiIdx[iPage],&pCur->info);
+  }else{
+    assertCellInfo(pCur);
+  }
+}
+
+#ifndef NDEBUG  /* The next routine used only within assert() statements */
+/*
+** Return true if the given BtCursor is valid.  A valid cursor is one
+** that is currently pointing to a row in a (non-empty) table.
+** This is a verification routine is used only within assert() statements.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCursorIsValid(BtCursor *pCur){
+  return pCur && pCur->eState==CURSOR_VALID;
+}
+#endif /* NDEBUG */
+
+/*
+** Return the value of the integer key or "rowid" for a table btree.
+** This routine is only valid for a cursor that is pointing into a
+** ordinary table btree.  If the cursor points to an index btree or
+** is invalid, the result of this routine is undefined.
+*/
+SQLITE_PRIVATE i64 sqlite3BtreeIntegerKey(BtCursor *pCur){
+  assert( cursorHoldsMutex(pCur) );
+  assert( pCur->eState==CURSOR_VALID );
+  assert( pCur->curIntKey );
+  getCellInfo(pCur);
+  return pCur->info.nKey;
+}
+
+/*
+** Return the number of bytes of payload for the entry that pCur is
+** currently pointing to.  For table btrees, this will be the amount
+** of data.  For index btrees, this will be the size of the key.
+**
+** The caller must guarantee that the cursor is pointing to a non-NULL
+** valid entry.  In other words, the calling procedure must guarantee
+** that the cursor has Cursor.eState==CURSOR_VALID.
+*/
+SQLITE_PRIVATE u32 sqlite3BtreePayloadSize(BtCursor *pCur){
+  assert( cursorHoldsMutex(pCur) );
+  assert( pCur->eState==CURSOR_VALID );
+  getCellInfo(pCur);
+  return pCur->info.nPayload;
+}
+
+/*
+** Given the page number of an overflow page in the database (parameter
+** ovfl), this function finds the page number of the next page in the 
+** linked list of overflow pages. If possible, it uses the auto-vacuum
+** pointer-map data instead of reading the content of page ovfl to do so. 
+**
+** If an error occurs an SQLite error code is returned. Otherwise:
+**
+** The page number of the next overflow page in the linked list is 
+** written to *pPgnoNext. If page ovfl is the last page in its linked 
+** list, *pPgnoNext is set to zero. 
+**
+** If ppPage is not NULL, and a reference to the MemPage object corresponding
+** to page number pOvfl was obtained, then *ppPage is set to point to that
+** reference. It is the responsibility of the caller to call releasePage()
+** on *ppPage to free the reference. In no reference was obtained (because
+** the pointer-map was used to obtain the value for *pPgnoNext), then
+** *ppPage is set to zero.
+*/
+static int getOverflowPage(
+  BtShared *pBt,               /* The database file */
+  Pgno ovfl,                   /* Current overflow page number */
+  MemPage **ppPage,            /* OUT: MemPage handle (may be NULL) */
+  Pgno *pPgnoNext              /* OUT: Next overflow page number */
+){
+  Pgno next = 0;
+  MemPage *pPage = 0;
+  int rc = SQLITE_OK;
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert(pPgnoNext);
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+  /* Try to find the next page in the overflow list using the
+  ** autovacuum pointer-map pages. Guess that the next page in 
+  ** the overflow list is page number (ovfl+1). If that guess turns 
+  ** out to be wrong, fall back to loading the data of page 
+  ** number ovfl to determine the next page number.
+  */
+  if( pBt->autoVacuum ){
+    Pgno pgno;
+    Pgno iGuess = ovfl+1;
+    u8 eType;
+
+    while( PTRMAP_ISPAGE(pBt, iGuess) || iGuess==PENDING_BYTE_PAGE(pBt) ){
+      iGuess++;
+    }
+
+    if( iGuess<=btreePagecount(pBt) ){
+      rc = ptrmapGet(pBt, iGuess, &eType, &pgno);
+      if( rc==SQLITE_OK && eType==PTRMAP_OVERFLOW2 && pgno==ovfl ){
+        next = iGuess;
+        rc = SQLITE_DONE;
+      }
+    }
+  }
+#endif
+
+  assert( next==0 || rc==SQLITE_DONE );
+  if( rc==SQLITE_OK ){
+    rc = btreeGetPage(pBt, ovfl, &pPage, (ppPage==0) ? PAGER_GET_READONLY : 0);
+    assert( rc==SQLITE_OK || pPage==0 );
+    if( rc==SQLITE_OK ){
+      next = get4byte(pPage->aData);
+    }
+  }
+
+  *pPgnoNext = next;
+  if( ppPage ){
+    *ppPage = pPage;
+  }else{
+    releasePage(pPage);
+  }
+  return (rc==SQLITE_DONE ? SQLITE_OK : rc);
+}
+
+/*
+** Copy data from a buffer to a page, or from a page to a buffer.
+**
+** pPayload is a pointer to data stored on database page pDbPage.
+** If argument eOp is false, then nByte bytes of data are copied
+** from pPayload to the buffer pointed at by pBuf. If eOp is true,
+** then sqlite3PagerWrite() is called on pDbPage and nByte bytes
+** of data are copied from the buffer pBuf to pPayload.
+**
+** SQLITE_OK is returned on success, otherwise an error code.
+*/
+static int copyPayload(
+  void *pPayload,           /* Pointer to page data */
+  void *pBuf,               /* Pointer to buffer */
+  int nByte,                /* Number of bytes to copy */
+  int eOp,                  /* 0 -> copy from page, 1 -> copy to page */
+  DbPage *pDbPage           /* Page containing pPayload */
+){
+  if( eOp ){
+    /* Copy data from buffer to page (a write operation) */
+    int rc = sqlite3PagerWrite(pDbPage);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    memcpy(pPayload, pBuf, nByte);
+  }else{
+    /* Copy data from page to buffer (a read operation) */
+    memcpy(pBuf, pPayload, nByte);
+  }
+  return SQLITE_OK;
+}
+
+/*
+** This function is used to read or overwrite payload information
+** for the entry that the pCur cursor is pointing to. The eOp
+** argument is interpreted as follows:
+**
+**   0: The operation is a read. Populate the overflow cache.
+**   1: The operation is a write. Populate the overflow cache.
+**   2: The operation is a read. Do not populate the overflow cache.
+**
+** A total of "amt" bytes are read or written beginning at "offset".
+** Data is read to or from the buffer pBuf.
+**
+** The content being read or written might appear on the main page
+** or be scattered out on multiple overflow pages.
+**
+** If the current cursor entry uses one or more overflow pages and the
+** eOp argument is not 2, this function may allocate space for and lazily 
+** populates the overflow page-list cache array (BtCursor.aOverflow). 
+** Subsequent calls use this cache to make seeking to the supplied offset 
+** more efficient.
+**
+** Once an overflow page-list cache has been allocated, it may be
+** invalidated if some other cursor writes to the same table, or if
+** the cursor is moved to a different row. Additionally, in auto-vacuum
+** mode, the following events may invalidate an overflow page-list cache.
+**
+**   * An incremental vacuum,
+**   * A commit in auto_vacuum="full" mode,
+**   * Creating a table (may require moving an overflow page).
+*/
+static int accessPayload(
+  BtCursor *pCur,      /* Cursor pointing to entry to read from */
+  u32 offset,          /* Begin reading this far into payload */
+  u32 amt,             /* Read this many bytes */
+  unsigned char *pBuf, /* Write the bytes into this buffer */ 
+  int eOp              /* zero to read. non-zero to write. */
+){
+  unsigned char *aPayload;
+  int rc = SQLITE_OK;
+  int iIdx = 0;
+  MemPage *pPage = pCur->apPage[pCur->iPage]; /* Btree page of current entry */
+  BtShared *pBt = pCur->pBt;                  /* Btree this cursor belongs to */
+#ifdef SQLITE_DIRECT_OVERFLOW_READ
+  unsigned char * const pBufStart = pBuf;
+  int bEnd;                                 /* True if reading to end of data */
+#endif
+
+  assert( pPage );
+  assert( pCur->eState==CURSOR_VALID );
+  assert( pCur->aiIdx[pCur->iPage]<pPage->nCell );
+  assert( cursorHoldsMutex(pCur) );
+  assert( eOp!=2 || offset==0 );    /* Always start from beginning for eOp==2 */
+
+  getCellInfo(pCur);
+  aPayload = pCur->info.pPayload;
+#ifdef SQLITE_DIRECT_OVERFLOW_READ
+  bEnd = offset+amt==pCur->info.nPayload;
+#endif
+  assert( offset+amt <= pCur->info.nPayload );
+
+  assert( aPayload > pPage->aData );
+  if( (uptr)(aPayload - pPage->aData) > (pBt->usableSize - pCur->info.nLocal) ){
+    /* Trying to read or write past the end of the data is an error.  The
+    ** conditional above is really:
+    **    &aPayload[pCur->info.nLocal] > &pPage->aData[pBt->usableSize]
+    ** but is recast into its current form to avoid integer overflow problems
+    */
+    return SQLITE_CORRUPT_BKPT;
+  }
+
+  /* Check if data must be read/written to/from the btree page itself. */
+  if( offset<pCur->info.nLocal ){
+    int a = amt;
+    if( a+offset>pCur->info.nLocal ){
+      a = pCur->info.nLocal - offset;
+    }
+    rc = copyPayload(&aPayload[offset], pBuf, a, (eOp & 0x01), pPage->pDbPage);
+    offset = 0;
+    pBuf += a;
+    amt -= a;
+  }else{
+    offset -= pCur->info.nLocal;
+  }
+
+
+  if( rc==SQLITE_OK && amt>0 ){
+    const u32 ovflSize = pBt->usableSize - 4;  /* Bytes content per ovfl page */
+    Pgno nextPage;
+
+    nextPage = get4byte(&aPayload[pCur->info.nLocal]);
+
+    /* If the BtCursor.aOverflow[] has not been allocated, allocate it now.
+    ** Except, do not allocate aOverflow[] for eOp==2.
+    **
+    ** The aOverflow[] array is sized at one entry for each overflow page
+    ** in the overflow chain. The page number of the first overflow page is
+    ** stored in aOverflow[0], etc. A value of 0 in the aOverflow[] array
+    ** means "not yet known" (the cache is lazily populated).
+    */
+    if( eOp!=2 && (pCur->curFlags & BTCF_ValidOvfl)==0 ){
+      int nOvfl = (pCur->info.nPayload-pCur->info.nLocal+ovflSize-1)/ovflSize;
+      if( nOvfl>pCur->nOvflAlloc ){
+        Pgno *aNew = (Pgno*)sqlite3Realloc(
+            pCur->aOverflow, nOvfl*2*sizeof(Pgno)
+        );
+        if( aNew==0 ){
+          rc = SQLITE_NOMEM_BKPT;
+        }else{
+          pCur->nOvflAlloc = nOvfl*2;
+          pCur->aOverflow = aNew;
+        }
+      }
+      if( rc==SQLITE_OK ){
+        memset(pCur->aOverflow, 0, nOvfl*sizeof(Pgno));
+        pCur->curFlags |= BTCF_ValidOvfl;
+      }
+    }
+
+    /* If the overflow page-list cache has been allocated and the
+    ** entry for the first required overflow page is valid, skip
+    ** directly to it.
+    */
+    if( (pCur->curFlags & BTCF_ValidOvfl)!=0
+     && pCur->aOverflow[offset/ovflSize]
+    ){
+      iIdx = (offset/ovflSize);
+      nextPage = pCur->aOverflow[iIdx];
+      offset = (offset%ovflSize);
+    }
+
+    for( ; rc==SQLITE_OK && amt>0 && nextPage; iIdx++){
+
+      /* If required, populate the overflow page-list cache. */
+      if( (pCur->curFlags & BTCF_ValidOvfl)!=0 ){
+        assert( pCur->aOverflow[iIdx]==0
+                || pCur->aOverflow[iIdx]==nextPage
+                || CORRUPT_DB );
+        pCur->aOverflow[iIdx] = nextPage;
+      }
+
+      if( offset>=ovflSize ){
+        /* The only reason to read this page is to obtain the page
+        ** number for the next page in the overflow chain. The page
+        ** data is not required. So first try to lookup the overflow
+        ** page-list cache, if any, then fall back to the getOverflowPage()
+        ** function.
+        **
+        ** Note that the aOverflow[] array must be allocated because eOp!=2
+        ** here.  If eOp==2, then offset==0 and this branch is never taken.
+        */
+        assert( eOp!=2 );
+        assert( pCur->curFlags & BTCF_ValidOvfl );
+        assert( pCur->pBtree->db==pBt->db );
+        if( pCur->aOverflow[iIdx+1] ){
+          nextPage = pCur->aOverflow[iIdx+1];
+        }else{
+          rc = getOverflowPage(pBt, nextPage, 0, &nextPage);
+        }
+        offset -= ovflSize;
+      }else{
+        /* Need to read this page properly. It contains some of the
+        ** range of data that is being read (eOp==0) or written (eOp!=0).
+        */
+#ifdef SQLITE_DIRECT_OVERFLOW_READ
+        sqlite3_file *fd;
+#endif
+        int a = amt;
+        if( a + offset > ovflSize ){
+          a = ovflSize - offset;
+        }
+
+#ifdef SQLITE_DIRECT_OVERFLOW_READ
+        /* If all the following are true:
+        **
+        **   1) this is a read operation, and 
+        **   2) data is required from the start of this overflow page, and
+        **   3) the database is file-backed, and
+        **   4) there is no open write-transaction, and
+        **   5) the database is not a WAL database,
+        **   6) all data from the page is being read.
+        **   7) at least 4 bytes have already been read into the output buffer 
+        **
+        ** then data can be read directly from the database file into the
+        ** output buffer, bypassing the page-cache altogether. This speeds
+        ** up loading large records that span many overflow pages.
+        */
+        if( (eOp&0x01)==0                                      /* (1) */
+         && offset==0                                          /* (2) */
+         && (bEnd || a==ovflSize)                              /* (6) */
+         && pBt->inTransaction==TRANS_READ                     /* (4) */
+         && (fd = sqlite3PagerFile(pBt->pPager))->pMethods     /* (3) */
+         && 0==sqlite3PagerUseWal(pBt->pPager)                 /* (5) */
+         && &pBuf[-4]>=pBufStart                               /* (7) */
+        ){
+          u8 aSave[4];
+          u8 *aWrite = &pBuf[-4];
+          assert( aWrite>=pBufStart );                         /* hence (7) */
+          memcpy(aSave, aWrite, 4);
+          rc = sqlite3OsRead(fd, aWrite, a+4, (i64)pBt->pageSize*(nextPage-1));
+          nextPage = get4byte(aWrite);
+          memcpy(aWrite, aSave, 4);
+        }else
+#endif
+
+        {
+          DbPage *pDbPage;
+          rc = sqlite3PagerGet(pBt->pPager, nextPage, &pDbPage,
+              ((eOp&0x01)==0 ? PAGER_GET_READONLY : 0)
+          );
+          if( rc==SQLITE_OK ){
+            aPayload = sqlite3PagerGetData(pDbPage);
+            nextPage = get4byte(aPayload);
+            rc = copyPayload(&aPayload[offset+4], pBuf, a, (eOp&0x01), pDbPage);
+            sqlite3PagerUnref(pDbPage);
+            offset = 0;
+          }
+        }
+        amt -= a;
+        pBuf += a;
+      }
+    }
+  }
+
+  if( rc==SQLITE_OK && amt>0 ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+  return rc;
+}
+
+/*
+** Read part of the key associated with cursor pCur.  Exactly
+** "amt" bytes will be transferred into pBuf[].  The transfer
+** begins at "offset".
+**
+** The caller must ensure that pCur is pointing to a valid row
+** in the table.
+**
+** Return SQLITE_OK on success or an error code if anything goes
+** wrong.  An error is returned if "offset+amt" is larger than
+** the available payload.
+*/
+SQLITE_PRIVATE int sqlite3BtreeKey(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){
+  assert( cursorHoldsMutex(pCur) );
+  assert( pCur->eState==CURSOR_VALID );
+  assert( pCur->iPage>=0 && pCur->apPage[pCur->iPage] );
+  assert( pCur->aiIdx[pCur->iPage]<pCur->apPage[pCur->iPage]->nCell );
+  return accessPayload(pCur, offset, amt, (unsigned char*)pBuf, 0);
+}
+
+/*
+** Read part of the data associated with cursor pCur.  Exactly
+** "amt" bytes will be transfered into pBuf[].  The transfer
+** begins at "offset".
+**
+** Return SQLITE_OK on success or an error code if anything goes
+** wrong.  An error is returned if "offset+amt" is larger than
+** the available payload.
+*/
+SQLITE_PRIVATE int sqlite3BtreeData(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){
+  int rc;
+
+#ifndef SQLITE_OMIT_INCRBLOB
+  if ( pCur->eState==CURSOR_INVALID ){
+    return SQLITE_ABORT;
+  }
+#endif
+
+  assert( cursorOwnsBtShared(pCur) );
+  rc = restoreCursorPosition(pCur);
+  if( rc==SQLITE_OK ){
+    assert( pCur->eState==CURSOR_VALID );
+    assert( pCur->iPage>=0 && pCur->apPage[pCur->iPage] );
+    assert( pCur->aiIdx[pCur->iPage]<pCur->apPage[pCur->iPage]->nCell );
+    rc = accessPayload(pCur, offset, amt, pBuf, 0);
+  }
+  return rc;
+}
+
+/*
+** Return a pointer to payload information from the entry that the 
+** pCur cursor is pointing to.  The pointer is to the beginning of
+** the key if index btrees (pPage->intKey==0) and is the data for
+** table btrees (pPage->intKey==1). The number of bytes of available
+** key/data is written into *pAmt.  If *pAmt==0, then the value
+** returned will not be a valid pointer.
+**
+** This routine is an optimization.  It is common for the entire key
+** and data to fit on the local page and for there to be no overflow
+** pages.  When that is so, this routine can be used to access the
+** key and data without making a copy.  If the key and/or data spills
+** onto overflow pages, then accessPayload() must be used to reassemble
+** the key/data and copy it into a preallocated buffer.
+**
+** The pointer returned by this routine looks directly into the cached
+** page of the database.  The data might change or move the next time
+** any btree routine is called.
+*/
+static const void *fetchPayload(
+  BtCursor *pCur,      /* Cursor pointing to entry to read from */
+  u32 *pAmt            /* Write the number of available bytes here */
+){
+  u32 amt;
+  assert( pCur!=0 && pCur->iPage>=0 && pCur->apPage[pCur->iPage]);
+  assert( pCur->eState==CURSOR_VALID );
+  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
+  assert( cursorOwnsBtShared(pCur) );
+  assert( pCur->aiIdx[pCur->iPage]<pCur->apPage[pCur->iPage]->nCell );
+  assert( pCur->info.nSize>0 );
+  assert( pCur->info.pPayload>pCur->apPage[pCur->iPage]->aData || CORRUPT_DB );
+  assert( pCur->info.pPayload<pCur->apPage[pCur->iPage]->aDataEnd ||CORRUPT_DB);
+  amt = (int)(pCur->apPage[pCur->iPage]->aDataEnd - pCur->info.pPayload);
+  if( pCur->info.nLocal<amt ) amt = pCur->info.nLocal;
+  *pAmt = amt;
+  return (void*)pCur->info.pPayload;
+}
+
+
+/*
+** For the entry that cursor pCur is point to, return as
+** many bytes of the key or data as are available on the local
+** b-tree page.  Write the number of available bytes into *pAmt.
+**
+** The pointer returned is ephemeral.  The key/data may move
+** or be destroyed on the next call to any Btree routine,
+** including calls from other threads against the same cache.
+** Hence, a mutex on the BtShared should be held prior to calling
+** this routine.
+**
+** These routines is used to get quick access to key and data
+** in the common case where no overflow pages are used.
+*/
+SQLITE_PRIVATE const void *sqlite3BtreePayloadFetch(BtCursor *pCur, u32 *pAmt){
+  return fetchPayload(pCur, pAmt);
+}
+
+
+/*
+** Move the cursor down to a new child page.  The newPgno argument is the
+** page number of the child page to move to.
+**
+** This function returns SQLITE_CORRUPT if the page-header flags field of
+** the new child page does not match the flags field of the parent (i.e.
+** if an intkey page appears to be the parent of a non-intkey page, or
+** vice-versa).
+*/
+static int moveToChild(BtCursor *pCur, u32 newPgno){
+  BtShared *pBt = pCur->pBt;
+
+  assert( cursorOwnsBtShared(pCur) );
+  assert( pCur->eState==CURSOR_VALID );
+  assert( pCur->iPage<BTCURSOR_MAX_DEPTH );
+  assert( pCur->iPage>=0 );
+  if( pCur->iPage>=(BTCURSOR_MAX_DEPTH-1) ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+  pCur->info.nSize = 0;
+  pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl);
+  pCur->iPage++;
+  pCur->aiIdx[pCur->iPage] = 0;
+  return getAndInitPage(pBt, newPgno, &pCur->apPage[pCur->iPage],
+                        pCur, pCur->curPagerFlags);
+}
+
+#if SQLITE_DEBUG
+/*
+** Page pParent is an internal (non-leaf) tree page. This function 
+** asserts that page number iChild is the left-child if the iIdx'th
+** cell in page pParent. Or, if iIdx is equal to the total number of
+** cells in pParent, that page number iChild is the right-child of
+** the page.
+*/
+static void assertParentIndex(MemPage *pParent, int iIdx, Pgno iChild){
+  if( CORRUPT_DB ) return;  /* The conditions tested below might not be true
+                            ** in a corrupt database */
+  assert( iIdx<=pParent->nCell );
+  if( iIdx==pParent->nCell ){
+    assert( get4byte(&pParent->aData[pParent->hdrOffset+8])==iChild );
+  }else{
+    assert( get4byte(findCell(pParent, iIdx))==iChild );
+  }
+}
+#else
+#  define assertParentIndex(x,y,z) 
+#endif
+
+/*
+** Move the cursor up to the parent page.
+**
+** pCur->idx is set to the cell index that contains the pointer
+** to the page we are coming from.  If we are coming from the
+** right-most child page then pCur->idx is set to one more than
+** the largest cell index.
+*/
+static void moveToParent(BtCursor *pCur){
+  assert( cursorOwnsBtShared(pCur) );
+  assert( pCur->eState==CURSOR_VALID );
+  assert( pCur->iPage>0 );
+  assert( pCur->apPage[pCur->iPage] );
+  assertParentIndex(
+    pCur->apPage[pCur->iPage-1], 
+    pCur->aiIdx[pCur->iPage-1], 
+    pCur->apPage[pCur->iPage]->pgno
+  );
+  testcase( pCur->aiIdx[pCur->iPage-1] > pCur->apPage[pCur->iPage-1]->nCell );
+  pCur->info.nSize = 0;
+  pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl);
+  releasePageNotNull(pCur->apPage[pCur->iPage--]);
+}
+
+/*
+** Move the cursor to point to the root page of its b-tree structure.
+**
+** If the table has a virtual root page, then the cursor is moved to point
+** to the virtual root page instead of the actual root page. A table has a
+** virtual root page when the actual root page contains no cells and a 
+** single child page. This can only happen with the table rooted at page 1.
+**
+** If the b-tree structure is empty, the cursor state is set to 
+** CURSOR_INVALID. Otherwise, the cursor is set to point to the first
+** cell located on the root (or virtual root) page and the cursor state
+** is set to CURSOR_VALID.
+**
+** If this function returns successfully, it may be assumed that the
+** page-header flags indicate that the [virtual] root-page is the expected 
+** kind of b-tree page (i.e. if when opening the cursor the caller did not
+** specify a KeyInfo structure the flags byte is set to 0x05 or 0x0D,
+** indicating a table b-tree, or if the caller did specify a KeyInfo 
+** structure the flags byte is set to 0x02 or 0x0A, indicating an index
+** b-tree).
+*/
+static int moveToRoot(BtCursor *pCur){
+  MemPage *pRoot;
+  int rc = SQLITE_OK;
+
+  assert( cursorOwnsBtShared(pCur) );
+  assert( CURSOR_INVALID < CURSOR_REQUIRESEEK );
+  assert( CURSOR_VALID   < CURSOR_REQUIRESEEK );
+  assert( CURSOR_FAULT   > CURSOR_REQUIRESEEK );
+  if( pCur->eState>=CURSOR_REQUIRESEEK ){
+    if( pCur->eState==CURSOR_FAULT ){
+      assert( pCur->skipNext!=SQLITE_OK );
+      return pCur->skipNext;
+    }
+    sqlite3BtreeClearCursor(pCur);
+  }
+
+  if( pCur->iPage>=0 ){
+    while( pCur->iPage ){
+      assert( pCur->apPage[pCur->iPage]!=0 );
+      releasePageNotNull(pCur->apPage[pCur->iPage--]);
+    }
+  }else if( pCur->pgnoRoot==0 ){
+    pCur->eState = CURSOR_INVALID;
+    return SQLITE_OK;
+  }else{
+    assert( pCur->iPage==(-1) );
+    rc = getAndInitPage(pCur->pBtree->pBt, pCur->pgnoRoot, &pCur->apPage[0],
+                        0, pCur->curPagerFlags);
+    if( rc!=SQLITE_OK ){
+      pCur->eState = CURSOR_INVALID;
+      return rc;
+    }
+    pCur->iPage = 0;
+    pCur->curIntKey = pCur->apPage[0]->intKey;
+  }
+  pRoot = pCur->apPage[0];
+  assert( pRoot->pgno==pCur->pgnoRoot );
+
+  /* If pCur->pKeyInfo is not NULL, then the caller that opened this cursor
+  ** expected to open it on an index b-tree. Otherwise, if pKeyInfo is
+  ** NULL, the caller expects a table b-tree. If this is not the case,
+  ** return an SQLITE_CORRUPT error. 
+  **
+  ** Earlier versions of SQLite assumed that this test could not fail
+  ** if the root page was already loaded when this function was called (i.e.
+  ** if pCur->iPage>=0). But this is not so if the database is corrupted 
+  ** in such a way that page pRoot is linked into a second b-tree table 
+  ** (or the freelist).  */
+  assert( pRoot->intKey==1 || pRoot->intKey==0 );
+  if( pRoot->isInit==0 || (pCur->pKeyInfo==0)!=pRoot->intKey ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+
+  pCur->aiIdx[0] = 0;
+  pCur->info.nSize = 0;
+  pCur->curFlags &= ~(BTCF_AtLast|BTCF_ValidNKey|BTCF_ValidOvfl);
+
+  if( pRoot->nCell>0 ){
+    pCur->eState = CURSOR_VALID;
+  }else if( !pRoot->leaf ){
+    Pgno subpage;
+    if( pRoot->pgno!=1 ) return SQLITE_CORRUPT_BKPT;
+    subpage = get4byte(&pRoot->aData[pRoot->hdrOffset+8]);
+    pCur->eState = CURSOR_VALID;
+    rc = moveToChild(pCur, subpage);
+  }else{
+    pCur->eState = CURSOR_INVALID;
+  }
+  return rc;
+}
+
+/*
+** Move the cursor down to the left-most leaf entry beneath the
+** entry to which it is currently pointing.
+**
+** The left-most leaf is the one with the smallest key - the first
+** in ascending order.
+*/
+static int moveToLeftmost(BtCursor *pCur){
+  Pgno pgno;
+  int rc = SQLITE_OK;
+  MemPage *pPage;
+
+  assert( cursorOwnsBtShared(pCur) );
+  assert( pCur->eState==CURSOR_VALID );
+  while( rc==SQLITE_OK && !(pPage = pCur->apPage[pCur->iPage])->leaf ){
+    assert( pCur->aiIdx[pCur->iPage]<pPage->nCell );
+    pgno = get4byte(findCell(pPage, pCur->aiIdx[pCur->iPage]));
+    rc = moveToChild(pCur, pgno);
+  }
+  return rc;
+}
+
+/*
+** Move the cursor down to the right-most leaf entry beneath the
+** page to which it is currently pointing.  Notice the difference
+** between moveToLeftmost() and moveToRightmost().  moveToLeftmost()
+** finds the left-most entry beneath the *entry* whereas moveToRightmost()
+** finds the right-most entry beneath the *page*.
+**
+** The right-most entry is the one with the largest key - the last
+** key in ascending order.
+*/
+static int moveToRightmost(BtCursor *pCur){
+  Pgno pgno;
+  int rc = SQLITE_OK;
+  MemPage *pPage = 0;
+
+  assert( cursorOwnsBtShared(pCur) );
+  assert( pCur->eState==CURSOR_VALID );
+  while( !(pPage = pCur->apPage[pCur->iPage])->leaf ){
+    pgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
+    pCur->aiIdx[pCur->iPage] = pPage->nCell;
+    rc = moveToChild(pCur, pgno);
+    if( rc ) return rc;
+  }
+  pCur->aiIdx[pCur->iPage] = pPage->nCell-1;
+  assert( pCur->info.nSize==0 );
+  assert( (pCur->curFlags & BTCF_ValidNKey)==0 );
+  return SQLITE_OK;
+}
+
+/* Move the cursor to the first entry in the table.  Return SQLITE_OK
+** on success.  Set *pRes to 0 if the cursor actually points to something
+** or set *pRes to 1 if the table is empty.
+*/
+SQLITE_PRIVATE int sqlite3BtreeFirst(BtCursor *pCur, int *pRes){
+  int rc;
+
+  assert( cursorOwnsBtShared(pCur) );
+  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
+  rc = moveToRoot(pCur);
+  if( rc==SQLITE_OK ){
+    if( pCur->eState==CURSOR_INVALID ){
+      assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage]->nCell==0 );
+      *pRes = 1;
+    }else{
+      assert( pCur->apPage[pCur->iPage]->nCell>0 );
+      *pRes = 0;
+      rc = moveToLeftmost(pCur);
+    }
+  }
+  return rc;
+}
+
+/* Move the cursor to the last entry in the table.  Return SQLITE_OK
+** on success.  Set *pRes to 0 if the cursor actually points to something
+** or set *pRes to 1 if the table is empty.
+*/
+SQLITE_PRIVATE int sqlite3BtreeLast(BtCursor *pCur, int *pRes){
+  int rc;
+ 
+  assert( cursorOwnsBtShared(pCur) );
+  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
+
+  /* If the cursor already points to the last entry, this is a no-op. */
+  if( CURSOR_VALID==pCur->eState && (pCur->curFlags & BTCF_AtLast)!=0 ){
+#ifdef SQLITE_DEBUG
+    /* This block serves to assert() that the cursor really does point 
+    ** to the last entry in the b-tree. */
+    int ii;
+    for(ii=0; ii<pCur->iPage; ii++){
+      assert( pCur->aiIdx[ii]==pCur->apPage[ii]->nCell );
+    }
+    assert( pCur->aiIdx[pCur->iPage]==pCur->apPage[pCur->iPage]->nCell-1 );
+    assert( pCur->apPage[pCur->iPage]->leaf );
+#endif
+    return SQLITE_OK;
+  }
+
+  rc = moveToRoot(pCur);
+  if( rc==SQLITE_OK ){
+    if( CURSOR_INVALID==pCur->eState ){
+      assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage]->nCell==0 );
+      *pRes = 1;
+    }else{
+      assert( pCur->eState==CURSOR_VALID );
+      *pRes = 0;
+      rc = moveToRightmost(pCur);
+      if( rc==SQLITE_OK ){
+        pCur->curFlags |= BTCF_AtLast;
+      }else{
+        pCur->curFlags &= ~BTCF_AtLast;
+      }
+   
+    }
+  }
+  return rc;
+}
+
+/* Move the cursor so that it points to an entry near the key 
+** specified by pIdxKey or intKey.   Return a success code.
+**
+** For INTKEY tables, the intKey parameter is used.  pIdxKey 
+** must be NULL.  For index tables, pIdxKey is used and intKey
+** is ignored.
+**
+** If an exact match is not found, then the cursor is always
+** left pointing at a leaf page which would hold the entry if it
+** were present.  The cursor might point to an entry that comes
+** before or after the key.
+**
+** An integer is written into *pRes which is the result of
+** comparing the key with the entry to which the cursor is 
+** pointing.  The meaning of the integer written into
+** *pRes is as follows:
+**
+**     *pRes<0      The cursor is left pointing at an entry that
+**                  is smaller than intKey/pIdxKey or if the table is empty
+**                  and the cursor is therefore left point to nothing.
+**
+**     *pRes==0     The cursor is left pointing at an entry that
+**                  exactly matches intKey/pIdxKey.
+**
+**     *pRes>0      The cursor is left pointing at an entry that
+**                  is larger than intKey/pIdxKey.
+**
+** For index tables, the pIdxKey->eqSeen field is set to 1 if there
+** exists an entry in the table that exactly matches pIdxKey.  
+*/
+SQLITE_PRIVATE int sqlite3BtreeMovetoUnpacked(
+  BtCursor *pCur,          /* The cursor to be moved */
+  UnpackedRecord *pIdxKey, /* Unpacked index key */
+  i64 intKey,              /* The table key */
+  int biasRight,           /* If true, bias the search to the high end */
+  int *pRes                /* Write search results here */
+){
+  int rc;
+  RecordCompare xRecordCompare;
+
+  assert( cursorOwnsBtShared(pCur) );
+  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
+  assert( pRes );
+  assert( (pIdxKey==0)==(pCur->pKeyInfo==0) );
+  assert( pCur->eState!=CURSOR_VALID || (pIdxKey==0)==(pCur->curIntKey!=0) );
+
+  /* If the cursor is already positioned at the point we are trying
+  ** to move to, then just return without doing any work */
+  if( pIdxKey==0
+   && pCur->eState==CURSOR_VALID && (pCur->curFlags & BTCF_ValidNKey)!=0
+  ){
+    if( pCur->info.nKey==intKey ){
+      *pRes = 0;
+      return SQLITE_OK;
+    }
+    if( (pCur->curFlags & BTCF_AtLast)!=0 && pCur->info.nKey<intKey ){
+      *pRes = -1;
+      return SQLITE_OK;
+    }
+  }
+
+  if( pIdxKey ){
+    xRecordCompare = sqlite3VdbeFindCompare(pIdxKey);
+    pIdxKey->errCode = 0;
+    assert( pIdxKey->default_rc==1 
+         || pIdxKey->default_rc==0 
+         || pIdxKey->default_rc==-1
+    );
+  }else{
+    xRecordCompare = 0; /* All keys are integers */
+  }
+
+  rc = moveToRoot(pCur);
+  if( rc ){
+    return rc;
+  }
+  assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage] );
+  assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage]->isInit );
+  assert( pCur->eState==CURSOR_INVALID || pCur->apPage[pCur->iPage]->nCell>0 );
+  if( pCur->eState==CURSOR_INVALID ){
+    *pRes = -1;
+    assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage]->nCell==0 );
+    return SQLITE_OK;
+  }
+  assert( pCur->apPage[0]->intKey==pCur->curIntKey );
+  assert( pCur->curIntKey || pIdxKey );
+  for(;;){
+    int lwr, upr, idx, c;
+    Pgno chldPg;
+    MemPage *pPage = pCur->apPage[pCur->iPage];
+    u8 *pCell;                          /* Pointer to current cell in pPage */
+
+    /* pPage->nCell must be greater than zero. If this is the root-page
+    ** the cursor would have been INVALID above and this for(;;) loop
+    ** not run. If this is not the root-page, then the moveToChild() routine
+    ** would have already detected db corruption. Similarly, pPage must
+    ** be the right kind (index or table) of b-tree page. Otherwise
+    ** a moveToChild() or moveToRoot() call would have detected corruption.  */
+    assert( pPage->nCell>0 );
+    assert( pPage->intKey==(pIdxKey==0) );
+    lwr = 0;
+    upr = pPage->nCell-1;
+    assert( biasRight==0 || biasRight==1 );
+    idx = upr>>(1-biasRight); /* idx = biasRight ? upr : (lwr+upr)/2; */
+    pCur->aiIdx[pCur->iPage] = (u16)idx;
+    if( xRecordCompare==0 ){
+      for(;;){
+        i64 nCellKey;
+        pCell = findCellPastPtr(pPage, idx);
+        if( pPage->intKeyLeaf ){
+          while( 0x80 <= *(pCell++) ){
+            if( pCell>=pPage->aDataEnd ) return SQLITE_CORRUPT_BKPT;
+          }
+        }
+        getVarint(pCell, (u64*)&nCellKey);
+        if( nCellKey<intKey ){
+          lwr = idx+1;
+          if( lwr>upr ){ c = -1; break; }
+        }else if( nCellKey>intKey ){
+          upr = idx-1;
+          if( lwr>upr ){ c = +1; break; }
+        }else{
+          assert( nCellKey==intKey );
+          pCur->curFlags |= BTCF_ValidNKey;
+          pCur->info.nKey = nCellKey;
+          pCur->aiIdx[pCur->iPage] = (u16)idx;
+          if( !pPage->leaf ){
+            lwr = idx;
+            goto moveto_next_layer;
+          }else{
+            *pRes = 0;
+            rc = SQLITE_OK;
+            goto moveto_finish;
+          }
+        }
+        assert( lwr+upr>=0 );
+        idx = (lwr+upr)>>1;  /* idx = (lwr+upr)/2; */
+      }
+    }else{
+      for(;;){
+        int nCell;  /* Size of the pCell cell in bytes */
+        pCell = findCellPastPtr(pPage, idx);
+
+        /* The maximum supported page-size is 65536 bytes. This means that
+        ** the maximum number of record bytes stored on an index B-Tree
+        ** page is less than 16384 bytes and may be stored as a 2-byte
+        ** varint. This information is used to attempt to avoid parsing 
+        ** the entire cell by checking for the cases where the record is 
+        ** stored entirely within the b-tree page by inspecting the first 
+        ** 2 bytes of the cell.
+        */
+        nCell = pCell[0];
+        if( nCell<=pPage->max1bytePayload ){
+          /* This branch runs if the record-size field of the cell is a
+          ** single byte varint and the record fits entirely on the main
+          ** b-tree page.  */
+          testcase( pCell+nCell+1==pPage->aDataEnd );
+          c = xRecordCompare(nCell, (void*)&pCell[1], pIdxKey);
+        }else if( !(pCell[1] & 0x80) 
+          && (nCell = ((nCell&0x7f)<<7) + pCell[1])<=pPage->maxLocal
+        ){
+          /* The record-size field is a 2 byte varint and the record 
+          ** fits entirely on the main b-tree page.  */
+          testcase( pCell+nCell+2==pPage->aDataEnd );
+          c = xRecordCompare(nCell, (void*)&pCell[2], pIdxKey);
+        }else{
+          /* The record flows over onto one or more overflow pages. In
+          ** this case the whole cell needs to be parsed, a buffer allocated
+          ** and accessPayload() used to retrieve the record into the
+          ** buffer before VdbeRecordCompare() can be called. 
+          **
+          ** If the record is corrupt, the xRecordCompare routine may read
+          ** up to two varints past the end of the buffer. An extra 18 
+          ** bytes of padding is allocated at the end of the buffer in
+          ** case this happens.  */
+          void *pCellKey;
+          u8 * const pCellBody = pCell - pPage->childPtrSize;
+          pPage->xParseCell(pPage, pCellBody, &pCur->info);
+          nCell = (int)pCur->info.nKey;
+          testcase( nCell<0 );   /* True if key size is 2^32 or more */
+          testcase( nCell==0 );  /* Invalid key size:  0x80 0x80 0x00 */
+          testcase( nCell==1 );  /* Invalid key size:  0x80 0x80 0x01 */
+          testcase( nCell==2 );  /* Minimum legal index key size */
+          if( nCell<2 ){
+            rc = SQLITE_CORRUPT_BKPT;
+            goto moveto_finish;
+          }
+          pCellKey = sqlite3Malloc( nCell+18 );
+          if( pCellKey==0 ){
+            rc = SQLITE_NOMEM_BKPT;
+            goto moveto_finish;
+          }
+          pCur->aiIdx[pCur->iPage] = (u16)idx;
+          rc = accessPayload(pCur, 0, nCell, (unsigned char*)pCellKey, 2);
+          if( rc ){
+            sqlite3_free(pCellKey);
+            goto moveto_finish;
+          }
+          c = xRecordCompare(nCell, pCellKey, pIdxKey);
+          sqlite3_free(pCellKey);
+        }
+        assert( 
+            (pIdxKey->errCode!=SQLITE_CORRUPT || c==0)
+         && (pIdxKey->errCode!=SQLITE_NOMEM || pCur->pBtree->db->mallocFailed)
+        );
+        if( c<0 ){
+          lwr = idx+1;
+        }else if( c>0 ){
+          upr = idx-1;
+        }else{
+          assert( c==0 );
+          *pRes = 0;
+          rc = SQLITE_OK;
+          pCur->aiIdx[pCur->iPage] = (u16)idx;
+          if( pIdxKey->errCode ) rc = SQLITE_CORRUPT;
+          goto moveto_finish;
+        }
+        if( lwr>upr ) break;
+        assert( lwr+upr>=0 );
+        idx = (lwr+upr)>>1;  /* idx = (lwr+upr)/2 */
+      }
+    }
+    assert( lwr==upr+1 || (pPage->intKey && !pPage->leaf) );
+    assert( pPage->isInit );
+    if( pPage->leaf ){
+      assert( pCur->aiIdx[pCur->iPage]<pCur->apPage[pCur->iPage]->nCell );
+      pCur->aiIdx[pCur->iPage] = (u16)idx;
+      *pRes = c;
+      rc = SQLITE_OK;
+      goto moveto_finish;
+    }
+moveto_next_layer:
+    if( lwr>=pPage->nCell ){
+      chldPg = get4byte(&pPage->aData[pPage->hdrOffset+8]);
+    }else{
+      chldPg = get4byte(findCell(pPage, lwr));
+    }
+    pCur->aiIdx[pCur->iPage] = (u16)lwr;
+    rc = moveToChild(pCur, chldPg);
+    if( rc ) break;
+  }
+moveto_finish:
+  pCur->info.nSize = 0;
+  pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl);
+  return rc;
+}
+
+
+/*
+** Return TRUE if the cursor is not pointing at an entry of the table.
+**
+** TRUE will be returned after a call to sqlite3BtreeNext() moves
+** past the last entry in the table or sqlite3BtreePrev() moves past
+** the first entry.  TRUE is also returned if the table is empty.
+*/
+SQLITE_PRIVATE int sqlite3BtreeEof(BtCursor *pCur){
+  /* TODO: What if the cursor is in CURSOR_REQUIRESEEK but all table entries
+  ** have been deleted? This API will need to change to return an error code
+  ** as well as the boolean result value.
+  */
+  return (CURSOR_VALID!=pCur->eState);
+}
+
+/*
+** Advance the cursor to the next entry in the database.  If
+** successful then set *pRes=0.  If the cursor
+** was already pointing to the last entry in the database before
+** this routine was called, then set *pRes=1.
+**
+** The main entry point is sqlite3BtreeNext().  That routine is optimized
+** for the common case of merely incrementing the cell counter BtCursor.aiIdx
+** to the next cell on the current page.  The (slower) btreeNext() helper
+** routine is called when it is necessary to move to a different page or
+** to restore the cursor.
+**
+** The calling function will set *pRes to 0 or 1.  The initial *pRes value
+** will be 1 if the cursor being stepped corresponds to an SQL index and
+** if this routine could have been skipped if that SQL index had been
+** a unique index.  Otherwise the caller will have set *pRes to zero.
+** Zero is the common case. The btree implementation is free to use the
+** initial *pRes value as a hint to improve performance, but the current
+** SQLite btree implementation does not. (Note that the comdb2 btree
+** implementation does use this hint, however.)
+*/
+static SQLITE_NOINLINE int btreeNext(BtCursor *pCur, int *pRes){
+  int rc;
+  int idx;
+  MemPage *pPage;
+
+  assert( cursorOwnsBtShared(pCur) );
+  assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID );
+  assert( *pRes==0 );
+  if( pCur->eState!=CURSOR_VALID ){
+    assert( (pCur->curFlags & BTCF_ValidOvfl)==0 );
+    rc = restoreCursorPosition(pCur);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    if( CURSOR_INVALID==pCur->eState ){
+      *pRes = 1;
+      return SQLITE_OK;
+    }
+    if( pCur->skipNext ){
+      assert( pCur->eState==CURSOR_VALID || pCur->eState==CURSOR_SKIPNEXT );
+      pCur->eState = CURSOR_VALID;
+      if( pCur->skipNext>0 ){
+        pCur->skipNext = 0;
+        return SQLITE_OK;
+      }
+      pCur->skipNext = 0;
+    }
+  }
+
+  pPage = pCur->apPage[pCur->iPage];
+  idx = ++pCur->aiIdx[pCur->iPage];
+  assert( pPage->isInit );
+
+  /* If the database file is corrupt, it is possible for the value of idx 
+  ** to be invalid here. This can only occur if a second cursor modifies
+  ** the page while cursor pCur is holding a reference to it. Which can
+  ** only happen if the database is corrupt in such a way as to link the
+  ** page into more than one b-tree structure. */
+  testcase( idx>pPage->nCell );
+
+  if( idx>=pPage->nCell ){
+    if( !pPage->leaf ){
+      rc = moveToChild(pCur, get4byte(&pPage->aData[pPage->hdrOffset+8]));
+      if( rc ) return rc;
+      return moveToLeftmost(pCur);
+    }
+    do{
+      if( pCur->iPage==0 ){
+        *pRes = 1;
+        pCur->eState = CURSOR_INVALID;
+        return SQLITE_OK;
+      }
+      moveToParent(pCur);
+      pPage = pCur->apPage[pCur->iPage];
+    }while( pCur->aiIdx[pCur->iPage]>=pPage->nCell );
+    if( pPage->intKey ){
+      return sqlite3BtreeNext(pCur, pRes);
+    }else{
+      return SQLITE_OK;
+    }
+  }
+  if( pPage->leaf ){
+    return SQLITE_OK;
+  }else{
+    return moveToLeftmost(pCur);
+  }
+}
+SQLITE_PRIVATE int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
+  MemPage *pPage;
+  assert( cursorOwnsBtShared(pCur) );
+  assert( pRes!=0 );
+  assert( *pRes==0 || *pRes==1 );
+  assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID );
+  pCur->info.nSize = 0;
+  pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl);
+  *pRes = 0;
+  if( pCur->eState!=CURSOR_VALID ) return btreeNext(pCur, pRes);
+  pPage = pCur->apPage[pCur->iPage];
+  if( (++pCur->aiIdx[pCur->iPage])>=pPage->nCell ){
+    pCur->aiIdx[pCur->iPage]--;
+    return btreeNext(pCur, pRes);
+  }
+  if( pPage->leaf ){
+    return SQLITE_OK;
+  }else{
+    return moveToLeftmost(pCur);
+  }
+}
+
+/*
+** Step the cursor to the back to the previous entry in the database.  If
+** successful then set *pRes=0.  If the cursor
+** was already pointing to the first entry in the database before
+** this routine was called, then set *pRes=1.
+**
+** The main entry point is sqlite3BtreePrevious().  That routine is optimized
+** for the common case of merely decrementing the cell counter BtCursor.aiIdx
+** to the previous cell on the current page.  The (slower) btreePrevious()
+** helper routine is called when it is necessary to move to a different page
+** or to restore the cursor.
+**
+** The calling function will set *pRes to 0 or 1.  The initial *pRes value
+** will be 1 if the cursor being stepped corresponds to an SQL index and
+** if this routine could have been skipped if that SQL index had been
+** a unique index.  Otherwise the caller will have set *pRes to zero.
+** Zero is the common case. The btree implementation is free to use the
+** initial *pRes value as a hint to improve performance, but the current
+** SQLite btree implementation does not. (Note that the comdb2 btree
+** implementation does use this hint, however.)
+*/
+static SQLITE_NOINLINE int btreePrevious(BtCursor *pCur, int *pRes){
+  int rc;
+  MemPage *pPage;
+
+  assert( cursorOwnsBtShared(pCur) );
+  assert( pRes!=0 );
+  assert( *pRes==0 );
+  assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID );
+  assert( (pCur->curFlags & (BTCF_AtLast|BTCF_ValidOvfl|BTCF_ValidNKey))==0 );
+  assert( pCur->info.nSize==0 );
+  if( pCur->eState!=CURSOR_VALID ){
+    rc = restoreCursorPosition(pCur);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    if( CURSOR_INVALID==pCur->eState ){
+      *pRes = 1;
+      return SQLITE_OK;
+    }
+    if( pCur->skipNext ){
+      assert( pCur->eState==CURSOR_VALID || pCur->eState==CURSOR_SKIPNEXT );
+      pCur->eState = CURSOR_VALID;
+      if( pCur->skipNext<0 ){
+        pCur->skipNext = 0;
+        return SQLITE_OK;
+      }
+      pCur->skipNext = 0;
+    }
+  }
+
+  pPage = pCur->apPage[pCur->iPage];
+  assert( pPage->isInit );
+  if( !pPage->leaf ){
+    int idx = pCur->aiIdx[pCur->iPage];
+    rc = moveToChild(pCur, get4byte(findCell(pPage, idx)));
+    if( rc ) return rc;
+    rc = moveToRightmost(pCur);
+  }else{
+    while( pCur->aiIdx[pCur->iPage]==0 ){
+      if( pCur->iPage==0 ){
+        pCur->eState = CURSOR_INVALID;
+        *pRes = 1;
+        return SQLITE_OK;
+      }
+      moveToParent(pCur);
+    }
+    assert( pCur->info.nSize==0 );
+    assert( (pCur->curFlags & (BTCF_ValidNKey|BTCF_ValidOvfl))==0 );
+
+    pCur->aiIdx[pCur->iPage]--;
+    pPage = pCur->apPage[pCur->iPage];
+    if( pPage->intKey && !pPage->leaf ){
+      rc = sqlite3BtreePrevious(pCur, pRes);
+    }else{
+      rc = SQLITE_OK;
+    }
+  }
+  return rc;
+}
+SQLITE_PRIVATE int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
+  assert( cursorOwnsBtShared(pCur) );
+  assert( pRes!=0 );
+  assert( *pRes==0 || *pRes==1 );
+  assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID );
+  *pRes = 0;
+  pCur->curFlags &= ~(BTCF_AtLast|BTCF_ValidOvfl|BTCF_ValidNKey);
+  pCur->info.nSize = 0;
+  if( pCur->eState!=CURSOR_VALID
+   || pCur->aiIdx[pCur->iPage]==0
+   || pCur->apPage[pCur->iPage]->leaf==0
+  ){
+    return btreePrevious(pCur, pRes);
+  }
+  pCur->aiIdx[pCur->iPage]--;
+  return SQLITE_OK;
+}
+
+/*
+** Allocate a new page from the database file.
+**
+** The new page is marked as dirty.  (In other words, sqlite3PagerWrite()
+** has already been called on the new page.)  The new page has also
+** been referenced and the calling routine is responsible for calling
+** sqlite3PagerUnref() on the new page when it is done.
+**
+** SQLITE_OK is returned on success.  Any other return value indicates
+** an error.  *ppPage is set to NULL in the event of an error.
+**
+** If the "nearby" parameter is not 0, then an effort is made to 
+** locate a page close to the page number "nearby".  This can be used in an
+** attempt to keep related pages close to each other in the database file,
+** which in turn can make database access faster.
+**
+** If the eMode parameter is BTALLOC_EXACT and the nearby page exists
+** anywhere on the free-list, then it is guaranteed to be returned.  If
+** eMode is BTALLOC_LT then the page returned will be less than or equal
+** to nearby if any such page exists.  If eMode is BTALLOC_ANY then there
+** are no restrictions on which page is returned.
+*/
+static int allocateBtreePage(
+  BtShared *pBt,         /* The btree */
+  MemPage **ppPage,      /* Store pointer to the allocated page here */
+  Pgno *pPgno,           /* Store the page number here */
+  Pgno nearby,           /* Search for a page near this one */
+  u8 eMode               /* BTALLOC_EXACT, BTALLOC_LT, or BTALLOC_ANY */
+){
+  MemPage *pPage1;
+  int rc;
+  u32 n;     /* Number of pages on the freelist */
+  u32 k;     /* Number of leaves on the trunk of the freelist */
+  MemPage *pTrunk = 0;
+  MemPage *pPrevTrunk = 0;
+  Pgno mxPage;     /* Total size of the database file */
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( eMode==BTALLOC_ANY || (nearby>0 && IfNotOmitAV(pBt->autoVacuum)) );
+  pPage1 = pBt->pPage1;
+  mxPage = btreePagecount(pBt);
+  /* EVIDENCE-OF: R-05119-02637 The 4-byte big-endian integer at offset 36
+  ** stores stores the total number of pages on the freelist. */
+  n = get4byte(&pPage1->aData[36]);
+  testcase( n==mxPage-1 );
+  if( n>=mxPage ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+  if( n>0 ){
+    /* There are pages on the freelist.  Reuse one of those pages. */
+    Pgno iTrunk;
+    u8 searchList = 0; /* If the free-list must be searched for 'nearby' */
+    u32 nSearch = 0;   /* Count of the number of search attempts */
+    
+    /* If eMode==BTALLOC_EXACT and a query of the pointer-map
+    ** shows that the page 'nearby' is somewhere on the free-list, then
+    ** the entire-list will be searched for that page.
+    */
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    if( eMode==BTALLOC_EXACT ){
+      if( nearby<=mxPage ){
+        u8 eType;
+        assert( nearby>0 );
+        assert( pBt->autoVacuum );
+        rc = ptrmapGet(pBt, nearby, &eType, 0);
+        if( rc ) return rc;
+        if( eType==PTRMAP_FREEPAGE ){
+          searchList = 1;
+        }
+      }
+    }else if( eMode==BTALLOC_LE ){
+      searchList = 1;
+    }
+#endif
+
+    /* Decrement the free-list count by 1. Set iTrunk to the index of the
+    ** first free-list trunk page. iPrevTrunk is initially 1.
+    */
+    rc = sqlite3PagerWrite(pPage1->pDbPage);
+    if( rc ) return rc;
+    put4byte(&pPage1->aData[36], n-1);
+
+    /* The code within this loop is run only once if the 'searchList' variable
+    ** is not true. Otherwise, it runs once for each trunk-page on the
+    ** free-list until the page 'nearby' is located (eMode==BTALLOC_EXACT)
+    ** or until a page less than 'nearby' is located (eMode==BTALLOC_LT)
+    */
+    do {
+      pPrevTrunk = pTrunk;
+      if( pPrevTrunk ){
+        /* EVIDENCE-OF: R-01506-11053 The first integer on a freelist trunk page
+        ** is the page number of the next freelist trunk page in the list or
+        ** zero if this is the last freelist trunk page. */
+        iTrunk = get4byte(&pPrevTrunk->aData[0]);
+      }else{
+        /* EVIDENCE-OF: R-59841-13798 The 4-byte big-endian integer at offset 32
+        ** stores the page number of the first page of the freelist, or zero if
+        ** the freelist is empty. */
+        iTrunk = get4byte(&pPage1->aData[32]);
+      }
+      testcase( iTrunk==mxPage );
+      if( iTrunk>mxPage || nSearch++ > n ){
+        rc = SQLITE_CORRUPT_BKPT;
+      }else{
+        rc = btreeGetUnusedPage(pBt, iTrunk, &pTrunk, 0);
+      }
+      if( rc ){
+        pTrunk = 0;
+        goto end_allocate_page;
+      }
+      assert( pTrunk!=0 );
+      assert( pTrunk->aData!=0 );
+      /* EVIDENCE-OF: R-13523-04394 The second integer on a freelist trunk page
+      ** is the number of leaf page pointers to follow. */
+      k = get4byte(&pTrunk->aData[4]);
+      if( k==0 && !searchList ){
+        /* The trunk has no leaves and the list is not being searched. 
+        ** So extract the trunk page itself and use it as the newly 
+        ** allocated page */
+        assert( pPrevTrunk==0 );
+        rc = sqlite3PagerWrite(pTrunk->pDbPage);
+        if( rc ){
+          goto end_allocate_page;
+        }
+        *pPgno = iTrunk;
+        memcpy(&pPage1->aData[32], &pTrunk->aData[0], 4);
+        *ppPage = pTrunk;
+        pTrunk = 0;
+        TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1));
+      }else if( k>(u32)(pBt->usableSize/4 - 2) ){
+        /* Value of k is out of range.  Database corruption */
+        rc = SQLITE_CORRUPT_BKPT;
+        goto end_allocate_page;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+      }else if( searchList 
+            && (nearby==iTrunk || (iTrunk<nearby && eMode==BTALLOC_LE)) 
+      ){
+        /* The list is being searched and this trunk page is the page
+        ** to allocate, regardless of whether it has leaves.
+        */
+        *pPgno = iTrunk;
+        *ppPage = pTrunk;
+        searchList = 0;
+        rc = sqlite3PagerWrite(pTrunk->pDbPage);
+        if( rc ){
+          goto end_allocate_page;
+        }
+        if( k==0 ){
+          if( !pPrevTrunk ){
+            memcpy(&pPage1->aData[32], &pTrunk->aData[0], 4);
+          }else{
+            rc = sqlite3PagerWrite(pPrevTrunk->pDbPage);
+            if( rc!=SQLITE_OK ){
+              goto end_allocate_page;
+            }
+            memcpy(&pPrevTrunk->aData[0], &pTrunk->aData[0], 4);
+          }
+        }else{
+          /* The trunk page is required by the caller but it contains 
+          ** pointers to free-list leaves. The first leaf becomes a trunk
+          ** page in this case.
+          */
+          MemPage *pNewTrunk;
+          Pgno iNewTrunk = get4byte(&pTrunk->aData[8]);
+          if( iNewTrunk>mxPage ){ 
+            rc = SQLITE_CORRUPT_BKPT;
+            goto end_allocate_page;
+          }
+          testcase( iNewTrunk==mxPage );
+          rc = btreeGetUnusedPage(pBt, iNewTrunk, &pNewTrunk, 0);
+          if( rc!=SQLITE_OK ){
+            goto end_allocate_page;
+          }
+          rc = sqlite3PagerWrite(pNewTrunk->pDbPage);
+          if( rc!=SQLITE_OK ){
+            releasePage(pNewTrunk);
+            goto end_allocate_page;
+          }
+          memcpy(&pNewTrunk->aData[0], &pTrunk->aData[0], 4);
+          put4byte(&pNewTrunk->aData[4], k-1);
+          memcpy(&pNewTrunk->aData[8], &pTrunk->aData[12], (k-1)*4);
+          releasePage(pNewTrunk);
+          if( !pPrevTrunk ){
+            assert( sqlite3PagerIswriteable(pPage1->pDbPage) );
+            put4byte(&pPage1->aData[32], iNewTrunk);
+          }else{
+            rc = sqlite3PagerWrite(pPrevTrunk->pDbPage);
+            if( rc ){
+              goto end_allocate_page;
+            }
+            put4byte(&pPrevTrunk->aData[0], iNewTrunk);
+          }
+        }
+        pTrunk = 0;
+        TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1));
+#endif
+      }else if( k>0 ){
+        /* Extract a leaf from the trunk */
+        u32 closest;
+        Pgno iPage;
+        unsigned char *aData = pTrunk->aData;
+        if( nearby>0 ){
+          u32 i;
+          closest = 0;
+          if( eMode==BTALLOC_LE ){
+            for(i=0; i<k; i++){
+              iPage = get4byte(&aData[8+i*4]);
+              if( iPage<=nearby ){
+                closest = i;
+                break;
+              }
+            }
+          }else{
+            int dist;
+            dist = sqlite3AbsInt32(get4byte(&aData[8]) - nearby);
+            for(i=1; i<k; i++){
+              int d2 = sqlite3AbsInt32(get4byte(&aData[8+i*4]) - nearby);
+              if( d2<dist ){
+                closest = i;
+                dist = d2;
+              }
+            }
+          }
+        }else{
+          closest = 0;
+        }
+
+        iPage = get4byte(&aData[8+closest*4]);
+        testcase( iPage==mxPage );
+        if( iPage>mxPage ){
+          rc = SQLITE_CORRUPT_BKPT;
+          goto end_allocate_page;
+        }
+        testcase( iPage==mxPage );
+        if( !searchList 
+         || (iPage==nearby || (iPage<nearby && eMode==BTALLOC_LE)) 
+        ){
+          int noContent;
+          *pPgno = iPage;
+          TRACE(("ALLOCATE: %d was leaf %d of %d on trunk %d"
+                 ": %d more free pages\n",
+                 *pPgno, closest+1, k, pTrunk->pgno, n-1));
+          rc = sqlite3PagerWrite(pTrunk->pDbPage);
+          if( rc ) goto end_allocate_page;
+          if( closest<k-1 ){
+            memcpy(&aData[8+closest*4], &aData[4+k*4], 4);
+          }
+          put4byte(&aData[4], k-1);
+          noContent = !btreeGetHasContent(pBt, *pPgno)? PAGER_GET_NOCONTENT : 0;
+          rc = btreeGetUnusedPage(pBt, *pPgno, ppPage, noContent);
+          if( rc==SQLITE_OK ){
+            rc = sqlite3PagerWrite((*ppPage)->pDbPage);
+            if( rc!=SQLITE_OK ){
+              releasePage(*ppPage);
+              *ppPage = 0;
+            }
+          }
+          searchList = 0;
+        }
+      }
+      releasePage(pPrevTrunk);
+      pPrevTrunk = 0;
+    }while( searchList );
+  }else{
+    /* There are no pages on the freelist, so append a new page to the
+    ** database image.
+    **
+    ** Normally, new pages allocated by this block can be requested from the
+    ** pager layer with the 'no-content' flag set. This prevents the pager
+    ** from trying to read the pages content from disk. However, if the
+    ** current transaction has already run one or more incremental-vacuum
+    ** steps, then the page we are about to allocate may contain content
+    ** that is required in the event of a rollback. In this case, do
+    ** not set the no-content flag. This causes the pager to load and journal
+    ** the current page content before overwriting it.
+    **
+    ** Note that the pager will not actually attempt to load or journal 
+    ** content for any page that really does lie past the end of the database
+    ** file on disk. So the effects of disabling the no-content optimization
+    ** here are confined to those pages that lie between the end of the
+    ** database image and the end of the database file.
+    */
+    int bNoContent = (0==IfNotOmitAV(pBt->bDoTruncate))? PAGER_GET_NOCONTENT:0;
+
+    rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
+    if( rc ) return rc;
+    pBt->nPage++;
+    if( pBt->nPage==PENDING_BYTE_PAGE(pBt) ) pBt->nPage++;
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    if( pBt->autoVacuum && PTRMAP_ISPAGE(pBt, pBt->nPage) ){
+      /* If *pPgno refers to a pointer-map page, allocate two new pages
+      ** at the end of the file instead of one. The first allocated page
+      ** becomes a new pointer-map page, the second is used by the caller.
+      */
+      MemPage *pPg = 0;
+      TRACE(("ALLOCATE: %d from end of file (pointer-map page)\n", pBt->nPage));
+      assert( pBt->nPage!=PENDING_BYTE_PAGE(pBt) );
+      rc = btreeGetUnusedPage(pBt, pBt->nPage, &pPg, bNoContent);
+      if( rc==SQLITE_OK ){
+        rc = sqlite3PagerWrite(pPg->pDbPage);
+        releasePage(pPg);
+      }
+      if( rc ) return rc;
+      pBt->nPage++;
+      if( pBt->nPage==PENDING_BYTE_PAGE(pBt) ){ pBt->nPage++; }
+    }
+#endif
+    put4byte(28 + (u8*)pBt->pPage1->aData, pBt->nPage);
+    *pPgno = pBt->nPage;
+
+    assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
+    rc = btreeGetUnusedPage(pBt, *pPgno, ppPage, bNoContent);
+    if( rc ) return rc;
+    rc = sqlite3PagerWrite((*ppPage)->pDbPage);
+    if( rc!=SQLITE_OK ){
+      releasePage(*ppPage);
+      *ppPage = 0;
+    }
+    TRACE(("ALLOCATE: %d from end of file\n", *pPgno));
+  }
+
+  assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
+
+end_allocate_page:
+  releasePage(pTrunk);
+  releasePage(pPrevTrunk);
+  assert( rc!=SQLITE_OK || sqlite3PagerPageRefcount((*ppPage)->pDbPage)<=1 );
+  assert( rc!=SQLITE_OK || (*ppPage)->isInit==0 );
+  return rc;
+}
+
+/*
+** This function is used to add page iPage to the database file free-list. 
+** It is assumed that the page is not already a part of the free-list.
+**
+** The value passed as the second argument to this function is optional.
+** If the caller happens to have a pointer to the MemPage object 
+** corresponding to page iPage handy, it may pass it as the second value. 
+** Otherwise, it may pass NULL.
+**
+** If a pointer to a MemPage object is passed as the second argument,
+** its reference count is not altered by this function.
+*/
+static int freePage2(BtShared *pBt, MemPage *pMemPage, Pgno iPage){
+  MemPage *pTrunk = 0;                /* Free-list trunk page */
+  Pgno iTrunk = 0;                    /* Page number of free-list trunk page */ 
+  MemPage *pPage1 = pBt->pPage1;      /* Local reference to page 1 */
+  MemPage *pPage;                     /* Page being freed. May be NULL. */
+  int rc;                             /* Return Code */
+  int nFree;                          /* Initial number of pages on free-list */
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( CORRUPT_DB || iPage>1 );
+  assert( !pMemPage || pMemPage->pgno==iPage );
+
+  if( iPage<2 ) return SQLITE_CORRUPT_BKPT;
+  if( pMemPage ){
+    pPage = pMemPage;
+    sqlite3PagerRef(pPage->pDbPage);
+  }else{
+    pPage = btreePageLookup(pBt, iPage);
+  }
+
+  /* Increment the free page count on pPage1 */
+  rc = sqlite3PagerWrite(pPage1->pDbPage);
+  if( rc ) goto freepage_out;
+  nFree = get4byte(&pPage1->aData[36]);
+  put4byte(&pPage1->aData[36], nFree+1);
+
+  if( pBt->btsFlags & BTS_SECURE_DELETE ){
+    /* If the secure_delete option is enabled, then
+    ** always fully overwrite deleted information with zeros.
+    */
+    if( (!pPage && ((rc = btreeGetPage(pBt, iPage, &pPage, 0))!=0) )
+     ||            ((rc = sqlite3PagerWrite(pPage->pDbPage))!=0)
+    ){
+      goto freepage_out;
+    }
+    memset(pPage->aData, 0, pPage->pBt->pageSize);
+  }
+
+  /* If the database supports auto-vacuum, write an entry in the pointer-map
+  ** to indicate that the page is free.
+  */
+  if( ISAUTOVACUUM ){
+    ptrmapPut(pBt, iPage, PTRMAP_FREEPAGE, 0, &rc);
+    if( rc ) goto freepage_out;
+  }
+
+  /* Now manipulate the actual database free-list structure. There are two
+  ** possibilities. If the free-list is currently empty, or if the first
+  ** trunk page in the free-list is full, then this page will become a
+  ** new free-list trunk page. Otherwise, it will become a leaf of the
+  ** first trunk page in the current free-list. This block tests if it
+  ** is possible to add the page as a new free-list leaf.
+  */
+  if( nFree!=0 ){
+    u32 nLeaf;                /* Initial number of leaf cells on trunk page */
+
+    iTrunk = get4byte(&pPage1->aData[32]);
+    rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0);
+    if( rc!=SQLITE_OK ){
+      goto freepage_out;
+    }
+
+    nLeaf = get4byte(&pTrunk->aData[4]);
+    assert( pBt->usableSize>32 );
+    if( nLeaf > (u32)pBt->usableSize/4 - 2 ){
+      rc = SQLITE_CORRUPT_BKPT;
+      goto freepage_out;
+    }
+    if( nLeaf < (u32)pBt->usableSize/4 - 8 ){
+      /* In this case there is room on the trunk page to insert the page
+      ** being freed as a new leaf.
+      **
+      ** Note that the trunk page is not really full until it contains
+      ** usableSize/4 - 2 entries, not usableSize/4 - 8 entries as we have
+      ** coded.  But due to a coding error in versions of SQLite prior to
+      ** 3.6.0, databases with freelist trunk pages holding more than
+      ** usableSize/4 - 8 entries will be reported as corrupt.  In order
+      ** to maintain backwards compatibility with older versions of SQLite,
+      ** we will continue to restrict the number of entries to usableSize/4 - 8
+      ** for now.  At some point in the future (once everyone has upgraded
+      ** to 3.6.0 or later) we should consider fixing the conditional above
+      ** to read "usableSize/4-2" instead of "usableSize/4-8".
+      **
+      ** EVIDENCE-OF: R-19920-11576 However, newer versions of SQLite still
+      ** avoid using the last six entries in the freelist trunk page array in
+      ** order that database files created by newer versions of SQLite can be
+      ** read by older versions of SQLite.
+      */
+      rc = sqlite3PagerWrite(pTrunk->pDbPage);
+      if( rc==SQLITE_OK ){
+        put4byte(&pTrunk->aData[4], nLeaf+1);
+        put4byte(&pTrunk->aData[8+nLeaf*4], iPage);
+        if( pPage && (pBt->btsFlags & BTS_SECURE_DELETE)==0 ){
+          sqlite3PagerDontWrite(pPage->pDbPage);
+        }
+        rc = btreeSetHasContent(pBt, iPage);
+      }
+      TRACE(("FREE-PAGE: %d leaf on trunk page %d\n",pPage->pgno,pTrunk->pgno));
+      goto freepage_out;
+    }
+  }
+
+  /* If control flows to this point, then it was not possible to add the
+  ** the page being freed as a leaf page of the first trunk in the free-list.
+  ** Possibly because the free-list is empty, or possibly because the 
+  ** first trunk in the free-list is full. Either way, the page being freed
+  ** will become the new first trunk page in the free-list.
+  */
+  if( pPage==0 && SQLITE_OK!=(rc = btreeGetPage(pBt, iPage, &pPage, 0)) ){
+    goto freepage_out;
+  }
+  rc = sqlite3PagerWrite(pPage->pDbPage);
+  if( rc!=SQLITE_OK ){
+    goto freepage_out;
+  }
+  put4byte(pPage->aData, iTrunk);
+  put4byte(&pPage->aData[4], 0);
+  put4byte(&pPage1->aData[32], iPage);
+  TRACE(("FREE-PAGE: %d new trunk page replacing %d\n", pPage->pgno, iTrunk));
+
+freepage_out:
+  if( pPage ){
+    pPage->isInit = 0;
+  }
+  releasePage(pPage);
+  releasePage(pTrunk);
+  return rc;
+}
+static void freePage(MemPage *pPage, int *pRC){
+  if( (*pRC)==SQLITE_OK ){
+    *pRC = freePage2(pPage->pBt, pPage, pPage->pgno);
+  }
+}
+
+/*
+** Free any overflow pages associated with the given Cell.  Write the
+** local Cell size (the number of bytes on the original page, omitting
+** overflow) into *pnSize.
+*/
+static int clearCell(
+  MemPage *pPage,          /* The page that contains the Cell */
+  unsigned char *pCell,    /* First byte of the Cell */
+  u16 *pnSize              /* Write the size of the Cell here */
+){
+  BtShared *pBt = pPage->pBt;
+  CellInfo info;
+  Pgno ovflPgno;
+  int rc;
+  int nOvfl;
+  u32 ovflPageSize;
+
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  pPage->xParseCell(pPage, pCell, &info);
+  *pnSize = info.nSize;
+  if( info.nLocal==info.nPayload ){
+    return SQLITE_OK;  /* No overflow pages. Return without doing anything */
+  }
+  if( pCell+info.nSize-1 > pPage->aData+pPage->maskPage ){
+    return SQLITE_CORRUPT_BKPT;  /* Cell extends past end of page */
+  }
+  ovflPgno = get4byte(pCell + info.nSize - 4);
+  assert( pBt->usableSize > 4 );
+  ovflPageSize = pBt->usableSize - 4;
+  nOvfl = (info.nPayload - info.nLocal + ovflPageSize - 1)/ovflPageSize;
+  assert( nOvfl>0 || 
+    (CORRUPT_DB && (info.nPayload + ovflPageSize)<ovflPageSize)
+  );
+  while( nOvfl-- ){
+    Pgno iNext = 0;
+    MemPage *pOvfl = 0;
+    if( ovflPgno<2 || ovflPgno>btreePagecount(pBt) ){
+      /* 0 is not a legal page number and page 1 cannot be an 
+      ** overflow page. Therefore if ovflPgno<2 or past the end of the 
+      ** file the database must be corrupt. */
+      return SQLITE_CORRUPT_BKPT;
+    }
+    if( nOvfl ){
+      rc = getOverflowPage(pBt, ovflPgno, &pOvfl, &iNext);
+      if( rc ) return rc;
+    }
+
+    if( ( pOvfl || ((pOvfl = btreePageLookup(pBt, ovflPgno))!=0) )
+     && sqlite3PagerPageRefcount(pOvfl->pDbPage)!=1
+    ){
+      /* There is no reason any cursor should have an outstanding reference 
+      ** to an overflow page belonging to a cell that is being deleted/updated.
+      ** So if there exists more than one reference to this page, then it 
+      ** must not really be an overflow page and the database must be corrupt. 
+      ** It is helpful to detect this before calling freePage2(), as 
+      ** freePage2() may zero the page contents if secure-delete mode is
+      ** enabled. If this 'overflow' page happens to be a page that the
+      ** caller is iterating through or using in some other way, this
+      ** can be problematic.
+      */
+      rc = SQLITE_CORRUPT_BKPT;
+    }else{
+      rc = freePage2(pBt, pOvfl, ovflPgno);
+    }
+
+    if( pOvfl ){
+      sqlite3PagerUnref(pOvfl->pDbPage);
+    }
+    if( rc ) return rc;
+    ovflPgno = iNext;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Create the byte sequence used to represent a cell on page pPage
+** and write that byte sequence into pCell[].  Overflow pages are
+** allocated and filled in as necessary.  The calling procedure
+** is responsible for making sure sufficient space has been allocated
+** for pCell[].
+**
+** Note that pCell does not necessary need to point to the pPage->aData
+** area.  pCell might point to some temporary storage.  The cell will
+** be constructed in this temporary area then copied into pPage->aData
+** later.
+*/
+static int fillInCell(
+  MemPage *pPage,                /* The page that contains the cell */
+  unsigned char *pCell,          /* Complete text of the cell */
+  const BtreePayload *pX,        /* Payload with which to construct the cell */
+  int *pnSize                    /* Write cell size here */
+){
+  int nPayload;
+  const u8 *pSrc;
+  int nSrc, n, rc;
+  int spaceLeft;
+  MemPage *pOvfl = 0;
+  MemPage *pToRelease = 0;
+  unsigned char *pPrior;
+  unsigned char *pPayload;
+  BtShared *pBt = pPage->pBt;
+  Pgno pgnoOvfl = 0;
+  int nHeader;
+
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+
+  /* pPage is not necessarily writeable since pCell might be auxiliary
+  ** buffer space that is separate from the pPage buffer area */
+  assert( pCell<pPage->aData || pCell>=&pPage->aData[pBt->pageSize]
+            || sqlite3PagerIswriteable(pPage->pDbPage) );
+
+  /* Fill in the header. */
+  nHeader = pPage->childPtrSize;
+  if( pPage->intKey ){
+    nPayload = pX->nData + pX->nZero;
+    pSrc = pX->pData;
+    nSrc = pX->nData;
+    assert( pPage->intKeyLeaf ); /* fillInCell() only called for leaves */
+    nHeader += putVarint32(&pCell[nHeader], nPayload);
+    nHeader += putVarint(&pCell[nHeader], *(u64*)&pX->nKey);
+  }else{
+    assert( pX->nKey<=0x7fffffff && pX->pKey!=0 );
+    nSrc = nPayload = (int)pX->nKey;
+    pSrc = pX->pKey;
+    nHeader += putVarint32(&pCell[nHeader], nPayload);
+  }
+  
+  /* Fill in the payload */
+  if( nPayload<=pPage->maxLocal ){
+    n = nHeader + nPayload;
+    testcase( n==3 );
+    testcase( n==4 );
+    if( n<4 ) n = 4;
+    *pnSize = n;
+    spaceLeft = nPayload;
+    pPrior = pCell;
+  }else{
+    int mn = pPage->minLocal;
+    n = mn + (nPayload - mn) % (pPage->pBt->usableSize - 4);
+    testcase( n==pPage->maxLocal );
+    testcase( n==pPage->maxLocal+1 );
+    if( n > pPage->maxLocal ) n = mn;
+    spaceLeft = n;
+    *pnSize = n + nHeader + 4;
+    pPrior = &pCell[nHeader+n];
+  }
+  pPayload = &pCell[nHeader];
+
+  /* At this point variables should be set as follows:
+  **
+  **   nPayload           Total payload size in bytes
+  **   pPayload           Begin writing payload here
+  **   spaceLeft          Space available at pPayload.  If nPayload>spaceLeft,
+  **                      that means content must spill into overflow pages.
+  **   *pnSize            Size of the local cell (not counting overflow pages)
+  **   pPrior             Where to write the pgno of the first overflow page
+  **
+  ** Use a call to btreeParseCellPtr() to verify that the values above
+  ** were computed correctly.
+  */
+#if SQLITE_DEBUG
+  {
+    CellInfo info;
+    pPage->xParseCell(pPage, pCell, &info);
+    assert( nHeader==(int)(info.pPayload - pCell) );
+    assert( info.nKey==pX->nKey );
+    assert( *pnSize == info.nSize );
+    assert( spaceLeft == info.nLocal );
+  }
+#endif
+
+  /* Write the payload into the local Cell and any extra into overflow pages */
+  while( nPayload>0 ){
+    if( spaceLeft==0 ){
+#ifndef SQLITE_OMIT_AUTOVACUUM
+      Pgno pgnoPtrmap = pgnoOvfl; /* Overflow page pointer-map entry page */
+      if( pBt->autoVacuum ){
+        do{
+          pgnoOvfl++;
+        } while( 
+          PTRMAP_ISPAGE(pBt, pgnoOvfl) || pgnoOvfl==PENDING_BYTE_PAGE(pBt) 
+        );
+      }
+#endif
+      rc = allocateBtreePage(pBt, &pOvfl, &pgnoOvfl, pgnoOvfl, 0);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+      /* If the database supports auto-vacuum, and the second or subsequent
+      ** overflow page is being allocated, add an entry to the pointer-map
+      ** for that page now. 
+      **
+      ** If this is the first overflow page, then write a partial entry 
+      ** to the pointer-map. If we write nothing to this pointer-map slot,
+      ** then the optimistic overflow chain processing in clearCell()
+      ** may misinterpret the uninitialized values and delete the
+      ** wrong pages from the database.
+      */
+      if( pBt->autoVacuum && rc==SQLITE_OK ){
+        u8 eType = (pgnoPtrmap?PTRMAP_OVERFLOW2:PTRMAP_OVERFLOW1);
+        ptrmapPut(pBt, pgnoOvfl, eType, pgnoPtrmap, &rc);
+        if( rc ){
+          releasePage(pOvfl);
+        }
+      }
+#endif
+      if( rc ){
+        releasePage(pToRelease);
+        return rc;
+      }
+
+      /* If pToRelease is not zero than pPrior points into the data area
+      ** of pToRelease.  Make sure pToRelease is still writeable. */
+      assert( pToRelease==0 || sqlite3PagerIswriteable(pToRelease->pDbPage) );
+
+      /* If pPrior is part of the data area of pPage, then make sure pPage
+      ** is still writeable */
+      assert( pPrior<pPage->aData || pPrior>=&pPage->aData[pBt->pageSize]
+            || sqlite3PagerIswriteable(pPage->pDbPage) );
+
+      put4byte(pPrior, pgnoOvfl);
+      releasePage(pToRelease);
+      pToRelease = pOvfl;
+      pPrior = pOvfl->aData;
+      put4byte(pPrior, 0);
+      pPayload = &pOvfl->aData[4];
+      spaceLeft = pBt->usableSize - 4;
+    }
+    n = nPayload;
+    if( n>spaceLeft ) n = spaceLeft;
+
+    /* If pToRelease is not zero than pPayload points into the data area
+    ** of pToRelease.  Make sure pToRelease is still writeable. */
+    assert( pToRelease==0 || sqlite3PagerIswriteable(pToRelease->pDbPage) );
+
+    /* If pPayload is part of the data area of pPage, then make sure pPage
+    ** is still writeable */
+    assert( pPayload<pPage->aData || pPayload>=&pPage->aData[pBt->pageSize]
+            || sqlite3PagerIswriteable(pPage->pDbPage) );
+
+    if( nSrc>0 ){
+      if( n>nSrc ) n = nSrc;
+      assert( pSrc );
+      memcpy(pPayload, pSrc, n);
+    }else{
+      memset(pPayload, 0, n);
+    }
+    nPayload -= n;
+    pPayload += n;
+    pSrc += n;
+    nSrc -= n;
+    spaceLeft -= n;
+  }
+  releasePage(pToRelease);
+  return SQLITE_OK;
+}
+
+/*
+** Remove the i-th cell from pPage.  This routine effects pPage only.
+** The cell content is not freed or deallocated.  It is assumed that
+** the cell content has been copied someplace else.  This routine just
+** removes the reference to the cell from pPage.
+**
+** "sz" must be the number of bytes in the cell.
+*/
+static void dropCell(MemPage *pPage, int idx, int sz, int *pRC){
+  u32 pc;         /* Offset to cell content of cell being deleted */
+  u8 *data;       /* pPage->aData */
+  u8 *ptr;        /* Used to move bytes around within data[] */
+  int rc;         /* The return code */
+  int hdr;        /* Beginning of the header.  0 most pages.  100 page 1 */
+
+  if( *pRC ) return;
+
+  assert( idx>=0 && idx<pPage->nCell );
+  assert( CORRUPT_DB || sz==cellSize(pPage, idx) );
+  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  data = pPage->aData;
+  ptr = &pPage->aCellIdx[2*idx];
+  pc = get2byte(ptr);
+  hdr = pPage->hdrOffset;
+  testcase( pc==get2byte(&data[hdr+5]) );
+  testcase( pc+sz==pPage->pBt->usableSize );
+  if( pc < (u32)get2byte(&data[hdr+5]) || pc+sz > pPage->pBt->usableSize ){
+    *pRC = SQLITE_CORRUPT_BKPT;
+    return;
+  }
+  rc = freeSpace(pPage, pc, sz);
+  if( rc ){
+    *pRC = rc;
+    return;
+  }
+  pPage->nCell--;
+  if( pPage->nCell==0 ){
+    memset(&data[hdr+1], 0, 4);
+    data[hdr+7] = 0;
+    put2byte(&data[hdr+5], pPage->pBt->usableSize);
+    pPage->nFree = pPage->pBt->usableSize - pPage->hdrOffset
+                       - pPage->childPtrSize - 8;
+  }else{
+    memmove(ptr, ptr+2, 2*(pPage->nCell - idx));
+    put2byte(&data[hdr+3], pPage->nCell);
+    pPage->nFree += 2;
+  }
+}
+
+/*
+** Insert a new cell on pPage at cell index "i".  pCell points to the
+** content of the cell.
+**
+** If the cell content will fit on the page, then put it there.  If it
+** will not fit, then make a copy of the cell content into pTemp if
+** pTemp is not null.  Regardless of pTemp, allocate a new entry
+** in pPage->apOvfl[] and make it point to the cell content (either
+** in pTemp or the original pCell) and also record its index. 
+** Allocating a new entry in pPage->aCell[] implies that 
+** pPage->nOverflow is incremented.
+**
+** *pRC must be SQLITE_OK when this routine is called.
+*/
+static void insertCell(
+  MemPage *pPage,   /* Page into which we are copying */
+  int i,            /* New cell becomes the i-th cell of the page */
+  u8 *pCell,        /* Content of the new cell */
+  int sz,           /* Bytes of content in pCell */
+  u8 *pTemp,        /* Temp storage space for pCell, if needed */
+  Pgno iChild,      /* If non-zero, replace first 4 bytes with this value */
+  int *pRC          /* Read and write return code from here */
+){
+  int idx = 0;      /* Where to write new cell content in data[] */
+  int j;            /* Loop counter */
+  u8 *data;         /* The content of the whole page */
+  u8 *pIns;         /* The point in pPage->aCellIdx[] where no cell inserted */
+
+  assert( *pRC==SQLITE_OK );
+  assert( i>=0 && i<=pPage->nCell+pPage->nOverflow );
+  assert( MX_CELL(pPage->pBt)<=10921 );
+  assert( pPage->nCell<=MX_CELL(pPage->pBt) || CORRUPT_DB );
+  assert( pPage->nOverflow<=ArraySize(pPage->apOvfl) );
+  assert( ArraySize(pPage->apOvfl)==ArraySize(pPage->aiOvfl) );
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  /* The cell should normally be sized correctly.  However, when moving a
+  ** malformed cell from a leaf page to an interior page, if the cell size
+  ** wanted to be less than 4 but got rounded up to 4 on the leaf, then size
+  ** might be less than 8 (leaf-size + pointer) on the interior node.  Hence
+  ** the term after the || in the following assert(). */
+  assert( sz==pPage->xCellSize(pPage, pCell) || (sz==8 && iChild>0) );
+  if( pPage->nOverflow || sz+2>pPage->nFree ){
+    if( pTemp ){
+      memcpy(pTemp, pCell, sz);
+      pCell = pTemp;
+    }
+    if( iChild ){
+      put4byte(pCell, iChild);
+    }
+    j = pPage->nOverflow++;
+    assert( j<(int)(sizeof(pPage->apOvfl)/sizeof(pPage->apOvfl[0])) );
+    pPage->apOvfl[j] = pCell;
+    pPage->aiOvfl[j] = (u16)i;
+
+    /* When multiple overflows occur, they are always sequential and in
+    ** sorted order.  This invariants arise because multiple overflows can
+    ** only occur when inserting divider cells into the parent page during
+    ** balancing, and the dividers are adjacent and sorted.
+    */
+    assert( j==0 || pPage->aiOvfl[j-1]<(u16)i ); /* Overflows in sorted order */
+    assert( j==0 || i==pPage->aiOvfl[j-1]+1 );   /* Overflows are sequential */
+  }else{
+    int rc = sqlite3PagerWrite(pPage->pDbPage);
+    if( rc!=SQLITE_OK ){
+      *pRC = rc;
+      return;
+    }
+    assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+    data = pPage->aData;
+    assert( &data[pPage->cellOffset]==pPage->aCellIdx );
+    rc = allocateSpace(pPage, sz, &idx);
+    if( rc ){ *pRC = rc; return; }
+    /* The allocateSpace() routine guarantees the following properties
+    ** if it returns successfully */
+    assert( idx >= 0 );
+    assert( idx >= pPage->cellOffset+2*pPage->nCell+2 || CORRUPT_DB );
+    assert( idx+sz <= (int)pPage->pBt->usableSize );
+    pPage->nFree -= (u16)(2 + sz);
+    memcpy(&data[idx], pCell, sz);
+    if( iChild ){
+      put4byte(&data[idx], iChild);
+    }
+    pIns = pPage->aCellIdx + i*2;
+    memmove(pIns+2, pIns, 2*(pPage->nCell - i));
+    put2byte(pIns, idx);
+    pPage->nCell++;
+    /* increment the cell count */
+    if( (++data[pPage->hdrOffset+4])==0 ) data[pPage->hdrOffset+3]++;
+    assert( get2byte(&data[pPage->hdrOffset+3])==pPage->nCell );
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    if( pPage->pBt->autoVacuum ){
+      /* The cell may contain a pointer to an overflow page. If so, write
+      ** the entry for the overflow page into the pointer map.
+      */
+      ptrmapPutOvflPtr(pPage, pCell, pRC);
+    }
+#endif
+  }
+}
+
+/*
+** A CellArray object contains a cache of pointers and sizes for a
+** consecutive sequence of cells that might be held on multiple pages.
+*/
+typedef struct CellArray CellArray;
+struct CellArray {
+  int nCell;              /* Number of cells in apCell[] */
+  MemPage *pRef;          /* Reference page */
+  u8 **apCell;            /* All cells begin balanced */
+  u16 *szCell;            /* Local size of all cells in apCell[] */
+};
+
+/*
+** Make sure the cell sizes at idx, idx+1, ..., idx+N-1 have been
+** computed.
+*/
+static void populateCellCache(CellArray *p, int idx, int N){
+  assert( idx>=0 && idx+N<=p->nCell );
+  while( N>0 ){
+    assert( p->apCell[idx]!=0 );
+    if( p->szCell[idx]==0 ){
+      p->szCell[idx] = p->pRef->xCellSize(p->pRef, p->apCell[idx]);
+    }else{
+      assert( CORRUPT_DB ||
+              p->szCell[idx]==p->pRef->xCellSize(p->pRef, p->apCell[idx]) );
+    }
+    idx++;
+    N--;
+  }
+}
+
+/*
+** Return the size of the Nth element of the cell array
+*/
+static SQLITE_NOINLINE u16 computeCellSize(CellArray *p, int N){
+  assert( N>=0 && N<p->nCell );
+  assert( p->szCell[N]==0 );
+  p->szCell[N] = p->pRef->xCellSize(p->pRef, p->apCell[N]);
+  return p->szCell[N];
+}
+static u16 cachedCellSize(CellArray *p, int N){
+  assert( N>=0 && N<p->nCell );
+  if( p->szCell[N] ) return p->szCell[N];
+  return computeCellSize(p, N);
+}
+
+/*
+** Array apCell[] contains pointers to nCell b-tree page cells. The 
+** szCell[] array contains the size in bytes of each cell. This function
+** replaces the current contents of page pPg with the contents of the cell
+** array.
+**
+** Some of the cells in apCell[] may currently be stored in pPg. This
+** function works around problems caused by this by making a copy of any 
+** such cells before overwriting the page data.
+**
+** The MemPage.nFree field is invalidated by this function. It is the 
+** responsibility of the caller to set it correctly.
+*/
+static int rebuildPage(
+  MemPage *pPg,                   /* Edit this page */
+  int nCell,                      /* Final number of cells on page */
+  u8 **apCell,                    /* Array of cells */
+  u16 *szCell                     /* Array of cell sizes */
+){
+  const int hdr = pPg->hdrOffset;          /* Offset of header on pPg */
+  u8 * const aData = pPg->aData;           /* Pointer to data for pPg */
+  const int usableSize = pPg->pBt->usableSize;
+  u8 * const pEnd = &aData[usableSize];
+  int i;
+  u8 *pCellptr = pPg->aCellIdx;
+  u8 *pTmp = sqlite3PagerTempSpace(pPg->pBt->pPager);
+  u8 *pData;
+
+  i = get2byte(&aData[hdr+5]);
+  memcpy(&pTmp[i], &aData[i], usableSize - i);
+
+  pData = pEnd;
+  for(i=0; i<nCell; i++){
+    u8 *pCell = apCell[i];
+    if( SQLITE_WITHIN(pCell,aData,pEnd) ){
+      pCell = &pTmp[pCell - aData];
+    }
+    pData -= szCell[i];
+    put2byte(pCellptr, (pData - aData));
+    pCellptr += 2;
+    if( pData < pCellptr ) return SQLITE_CORRUPT_BKPT;
+    memcpy(pData, pCell, szCell[i]);
+    assert( szCell[i]==pPg->xCellSize(pPg, pCell) || CORRUPT_DB );
+    testcase( szCell[i]!=pPg->xCellSize(pPg,pCell) );
+  }
+
+  /* The pPg->nFree field is now set incorrectly. The caller will fix it. */
+  pPg->nCell = nCell;
+  pPg->nOverflow = 0;
+
+  put2byte(&aData[hdr+1], 0);
+  put2byte(&aData[hdr+3], pPg->nCell);
+  put2byte(&aData[hdr+5], pData - aData);
+  aData[hdr+7] = 0x00;
+  return SQLITE_OK;
+}
+
+/*
+** Array apCell[] contains nCell pointers to b-tree cells. Array szCell
+** contains the size in bytes of each such cell. This function attempts to 
+** add the cells stored in the array to page pPg. If it cannot (because 
+** the page needs to be defragmented before the cells will fit), non-zero
+** is returned. Otherwise, if the cells are added successfully, zero is
+** returned.
+**
+** Argument pCellptr points to the first entry in the cell-pointer array
+** (part of page pPg) to populate. After cell apCell[0] is written to the
+** page body, a 16-bit offset is written to pCellptr. And so on, for each
+** cell in the array. It is the responsibility of the caller to ensure
+** that it is safe to overwrite this part of the cell-pointer array.
+**
+** When this function is called, *ppData points to the start of the 
+** content area on page pPg. If the size of the content area is extended,
+** *ppData is updated to point to the new start of the content area
+** before returning.
+**
+** Finally, argument pBegin points to the byte immediately following the
+** end of the space required by this page for the cell-pointer area (for
+** all cells - not just those inserted by the current call). If the content
+** area must be extended to before this point in order to accomodate all
+** cells in apCell[], then the cells do not fit and non-zero is returned.
+*/
+static int pageInsertArray(
+  MemPage *pPg,                   /* Page to add cells to */
+  u8 *pBegin,                     /* End of cell-pointer array */
+  u8 **ppData,                    /* IN/OUT: Page content -area pointer */
+  u8 *pCellptr,                   /* Pointer to cell-pointer area */
+  int iFirst,                     /* Index of first cell to add */
+  int nCell,                      /* Number of cells to add to pPg */
+  CellArray *pCArray              /* Array of cells */
+){
+  int i;
+  u8 *aData = pPg->aData;
+  u8 *pData = *ppData;
+  int iEnd = iFirst + nCell;
+  assert( CORRUPT_DB || pPg->hdrOffset==0 );    /* Never called on page 1 */
+  for(i=iFirst; i<iEnd; i++){
+    int sz, rc;
+    u8 *pSlot;
+    sz = cachedCellSize(pCArray, i);
+    if( (aData[1]==0 && aData[2]==0) || (pSlot = pageFindSlot(pPg,sz,&rc))==0 ){
+      if( (pData - pBegin)<sz ) return 1;
+      pData -= sz;
+      pSlot = pData;
+    }
+    /* pSlot and pCArray->apCell[i] will never overlap on a well-formed
+    ** database.  But they might for a corrupt database.  Hence use memmove()
+    ** since memcpy() sends SIGABORT with overlapping buffers on OpenBSD */
+    assert( (pSlot+sz)<=pCArray->apCell[i]
+         || pSlot>=(pCArray->apCell[i]+sz)
+         || CORRUPT_DB );
+    memmove(pSlot, pCArray->apCell[i], sz);
+    put2byte(pCellptr, (pSlot - aData));
+    pCellptr += 2;
+  }
+  *ppData = pData;
+  return 0;
+}
+
+/*
+** Array apCell[] contains nCell pointers to b-tree cells. Array szCell 
+** contains the size in bytes of each such cell. This function adds the
+** space associated with each cell in the array that is currently stored 
+** within the body of pPg to the pPg free-list. The cell-pointers and other
+** fields of the page are not updated.
+**
+** This function returns the total number of cells added to the free-list.
+*/
+static int pageFreeArray(
+  MemPage *pPg,                   /* Page to edit */
+  int iFirst,                     /* First cell to delete */
+  int nCell,                      /* Cells to delete */
+  CellArray *pCArray              /* Array of cells */
+){
+  u8 * const aData = pPg->aData;
+  u8 * const pEnd = &aData[pPg->pBt->usableSize];
+  u8 * const pStart = &aData[pPg->hdrOffset + 8 + pPg->childPtrSize];
+  int nRet = 0;
+  int i;
+  int iEnd = iFirst + nCell;
+  u8 *pFree = 0;
+  int szFree = 0;
+
+  for(i=iFirst; i<iEnd; i++){
+    u8 *pCell = pCArray->apCell[i];
+    if( SQLITE_WITHIN(pCell, pStart, pEnd) ){
+      int sz;
+      /* No need to use cachedCellSize() here.  The sizes of all cells that
+      ** are to be freed have already been computing while deciding which
+      ** cells need freeing */
+      sz = pCArray->szCell[i];  assert( sz>0 );
+      if( pFree!=(pCell + sz) ){
+        if( pFree ){
+          assert( pFree>aData && (pFree - aData)<65536 );
+          freeSpace(pPg, (u16)(pFree - aData), szFree);
+        }
+        pFree = pCell;
+        szFree = sz;
+        if( pFree+sz>pEnd ) return 0;
+      }else{
+        pFree = pCell;
+        szFree += sz;
+      }
+      nRet++;
+    }
+  }
+  if( pFree ){
+    assert( pFree>aData && (pFree - aData)<65536 );
+    freeSpace(pPg, (u16)(pFree - aData), szFree);
+  }
+  return nRet;
+}
+
+/*
+** apCell[] and szCell[] contains pointers to and sizes of all cells in the
+** pages being balanced.  The current page, pPg, has pPg->nCell cells starting
+** with apCell[iOld].  After balancing, this page should hold nNew cells
+** starting at apCell[iNew].
+**
+** This routine makes the necessary adjustments to pPg so that it contains
+** the correct cells after being balanced.
+**
+** The pPg->nFree field is invalid when this function returns. It is the
+** responsibility of the caller to set it correctly.
+*/
+static int editPage(
+  MemPage *pPg,                   /* Edit this page */
+  int iOld,                       /* Index of first cell currently on page */
+  int iNew,                       /* Index of new first cell on page */
+  int nNew,                       /* Final number of cells on page */
+  CellArray *pCArray              /* Array of cells and sizes */
+){
+  u8 * const aData = pPg->aData;
+  const int hdr = pPg->hdrOffset;
+  u8 *pBegin = &pPg->aCellIdx[nNew * 2];
+  int nCell = pPg->nCell;       /* Cells stored on pPg */
+  u8 *pData;
+  u8 *pCellptr;
+  int i;
+  int iOldEnd = iOld + pPg->nCell + pPg->nOverflow;
+  int iNewEnd = iNew + nNew;
+
+#ifdef SQLITE_DEBUG
+  u8 *pTmp = sqlite3PagerTempSpace(pPg->pBt->pPager);
+  memcpy(pTmp, aData, pPg->pBt->usableSize);
+#endif
+
+  /* Remove cells from the start and end of the page */
+  if( iOld<iNew ){
+    int nShift = pageFreeArray(pPg, iOld, iNew-iOld, pCArray);
+    memmove(pPg->aCellIdx, &pPg->aCellIdx[nShift*2], nCell*2);
+    nCell -= nShift;
+  }
+  if( iNewEnd < iOldEnd ){
+    nCell -= pageFreeArray(pPg, iNewEnd, iOldEnd - iNewEnd, pCArray);
+  }
+
+  pData = &aData[get2byteNotZero(&aData[hdr+5])];
+  if( pData<pBegin ) goto editpage_fail;
+
+  /* Add cells to the start of the page */
+  if( iNew<iOld ){
+    int nAdd = MIN(nNew,iOld-iNew);
+    assert( (iOld-iNew)<nNew || nCell==0 || CORRUPT_DB );
+    pCellptr = pPg->aCellIdx;
+    memmove(&pCellptr[nAdd*2], pCellptr, nCell*2);
+    if( pageInsertArray(
+          pPg, pBegin, &pData, pCellptr,
+          iNew, nAdd, pCArray
+    ) ) goto editpage_fail;
+    nCell += nAdd;
+  }
+
+  /* Add any overflow cells */
+  for(i=0; i<pPg->nOverflow; i++){
+    int iCell = (iOld + pPg->aiOvfl[i]) - iNew;
+    if( iCell>=0 && iCell<nNew ){
+      pCellptr = &pPg->aCellIdx[iCell * 2];
+      memmove(&pCellptr[2], pCellptr, (nCell - iCell) * 2);
+      nCell++;
+      if( pageInsertArray(
+            pPg, pBegin, &pData, pCellptr,
+            iCell+iNew, 1, pCArray
+      ) ) goto editpage_fail;
+    }
+  }
+
+  /* Append cells to the end of the page */
+  pCellptr = &pPg->aCellIdx[nCell*2];
+  if( pageInsertArray(
+        pPg, pBegin, &pData, pCellptr,
+        iNew+nCell, nNew-nCell, pCArray
+  ) ) goto editpage_fail;
+
+  pPg->nCell = nNew;
+  pPg->nOverflow = 0;
+
+  put2byte(&aData[hdr+3], pPg->nCell);
+  put2byte(&aData[hdr+5], pData - aData);
+
+#ifdef SQLITE_DEBUG
+  for(i=0; i<nNew && !CORRUPT_DB; i++){
+    u8 *pCell = pCArray->apCell[i+iNew];
+    int iOff = get2byteAligned(&pPg->aCellIdx[i*2]);
+    if( SQLITE_WITHIN(pCell, aData, &aData[pPg->pBt->usableSize]) ){
+      pCell = &pTmp[pCell - aData];
+    }
+    assert( 0==memcmp(pCell, &aData[iOff],
+            pCArray->pRef->xCellSize(pCArray->pRef, pCArray->apCell[i+iNew])) );
+  }
+#endif
+
+  return SQLITE_OK;
+ editpage_fail:
+  /* Unable to edit this page. Rebuild it from scratch instead. */
+  populateCellCache(pCArray, iNew, nNew);
+  return rebuildPage(pPg, nNew, &pCArray->apCell[iNew], &pCArray->szCell[iNew]);
+}
+
+/*
+** The following parameters determine how many adjacent pages get involved
+** in a balancing operation.  NN is the number of neighbors on either side
+** of the page that participate in the balancing operation.  NB is the
+** total number of pages that participate, including the target page and
+** NN neighbors on either side.
+**
+** The minimum value of NN is 1 (of course).  Increasing NN above 1
+** (to 2 or 3) gives a modest improvement in SELECT and DELETE performance
+** in exchange for a larger degradation in INSERT and UPDATE performance.
+** The value of NN appears to give the best results overall.
+*/
+#define NN 1             /* Number of neighbors on either side of pPage */
+#define NB (NN*2+1)      /* Total pages involved in the balance */
+
+
+#ifndef SQLITE_OMIT_QUICKBALANCE
+/*
+** This version of balance() handles the common special case where
+** a new entry is being inserted on the extreme right-end of the
+** tree, in other words, when the new entry will become the largest
+** entry in the tree.
+**
+** Instead of trying to balance the 3 right-most leaf pages, just add
+** a new page to the right-hand side and put the one new entry in
+** that page.  This leaves the right side of the tree somewhat
+** unbalanced.  But odds are that we will be inserting new entries
+** at the end soon afterwards so the nearly empty page will quickly
+** fill up.  On average.
+**
+** pPage is the leaf page which is the right-most page in the tree.
+** pParent is its parent.  pPage must have a single overflow entry
+** which is also the right-most entry on the page.
+**
+** The pSpace buffer is used to store a temporary copy of the divider
+** cell that will be inserted into pParent. Such a cell consists of a 4
+** byte page number followed by a variable length integer. In other
+** words, at most 13 bytes. Hence the pSpace buffer must be at
+** least 13 bytes in size.
+*/
+static int balance_quick(MemPage *pParent, MemPage *pPage, u8 *pSpace){
+  BtShared *const pBt = pPage->pBt;    /* B-Tree Database */
+  MemPage *pNew;                       /* Newly allocated page */
+  int rc;                              /* Return Code */
+  Pgno pgnoNew;                        /* Page number of pNew */
+
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  assert( sqlite3PagerIswriteable(pParent->pDbPage) );
+  assert( pPage->nOverflow==1 );
+
+  /* This error condition is now caught prior to reaching this function */
+  if( NEVER(pPage->nCell==0) ) return SQLITE_CORRUPT_BKPT;
+
+  /* Allocate a new page. This page will become the right-sibling of 
+  ** pPage. Make the parent page writable, so that the new divider cell
+  ** may be inserted. If both these operations are successful, proceed.
+  */
+  rc = allocateBtreePage(pBt, &pNew, &pgnoNew, 0, 0);
+
+  if( rc==SQLITE_OK ){
+
+    u8 *pOut = &pSpace[4];
+    u8 *pCell = pPage->apOvfl[0];
+    u16 szCell = pPage->xCellSize(pPage, pCell);
+    u8 *pStop;
+
+    assert( sqlite3PagerIswriteable(pNew->pDbPage) );
+    assert( pPage->aData[0]==(PTF_INTKEY|PTF_LEAFDATA|PTF_LEAF) );
+    zeroPage(pNew, PTF_INTKEY|PTF_LEAFDATA|PTF_LEAF);
+    rc = rebuildPage(pNew, 1, &pCell, &szCell);
+    if( NEVER(rc) ) return rc;
+    pNew->nFree = pBt->usableSize - pNew->cellOffset - 2 - szCell;
+
+    /* If this is an auto-vacuum database, update the pointer map
+    ** with entries for the new page, and any pointer from the 
+    ** cell on the page to an overflow page. If either of these
+    ** operations fails, the return code is set, but the contents
+    ** of the parent page are still manipulated by thh code below.
+    ** That is Ok, at this point the parent page is guaranteed to
+    ** be marked as dirty. Returning an error code will cause a
+    ** rollback, undoing any changes made to the parent page.
+    */
+    if( ISAUTOVACUUM ){
+      ptrmapPut(pBt, pgnoNew, PTRMAP_BTREE, pParent->pgno, &rc);
+      if( szCell>pNew->minLocal ){
+        ptrmapPutOvflPtr(pNew, pCell, &rc);
+      }
+    }
+  
+    /* Create a divider cell to insert into pParent. The divider cell
+    ** consists of a 4-byte page number (the page number of pPage) and
+    ** a variable length key value (which must be the same value as the
+    ** largest key on pPage).
+    **
+    ** To find the largest key value on pPage, first find the right-most 
+    ** cell on pPage. The first two fields of this cell are the 
+    ** record-length (a variable length integer at most 32-bits in size)
+    ** and the key value (a variable length integer, may have any value).
+    ** The first of the while(...) loops below skips over the record-length
+    ** field. The second while(...) loop copies the key value from the
+    ** cell on pPage into the pSpace buffer.
+    */
+    pCell = findCell(pPage, pPage->nCell-1);
+    pStop = &pCell[9];
+    while( (*(pCell++)&0x80) && pCell<pStop );
+    pStop = &pCell[9];
+    while( ((*(pOut++) = *(pCell++))&0x80) && pCell<pStop );
+
+    /* Insert the new divider cell into pParent. */
+    if( rc==SQLITE_OK ){
+      insertCell(pParent, pParent->nCell, pSpace, (int)(pOut-pSpace),
+                   0, pPage->pgno, &rc);
+    }
+
+    /* Set the right-child pointer of pParent to point to the new page. */
+    put4byte(&pParent->aData[pParent->hdrOffset+8], pgnoNew);
+  
+    /* Release the reference to the new page. */
+    releasePage(pNew);
+  }
+
+  return rc;
+}
+#endif /* SQLITE_OMIT_QUICKBALANCE */
+
+#if 0
+/*
+** This function does not contribute anything to the operation of SQLite.
+** it is sometimes activated temporarily while debugging code responsible 
+** for setting pointer-map entries.
+*/
+static int ptrmapCheckPages(MemPage **apPage, int nPage){
+  int i, j;
+  for(i=0; i<nPage; i++){
+    Pgno n;
+    u8 e;
+    MemPage *pPage = apPage[i];
+    BtShared *pBt = pPage->pBt;
+    assert( pPage->isInit );
+
+    for(j=0; j<pPage->nCell; j++){
+      CellInfo info;
+      u8 *z;
+     
+      z = findCell(pPage, j);
+      pPage->xParseCell(pPage, z, &info);
+      if( info.nLocal<info.nPayload ){
+        Pgno ovfl = get4byte(&z[info.nSize-4]);
+        ptrmapGet(pBt, ovfl, &e, &n);
+        assert( n==pPage->pgno && e==PTRMAP_OVERFLOW1 );
+      }
+      if( !pPage->leaf ){
+        Pgno child = get4byte(z);
+        ptrmapGet(pBt, child, &e, &n);
+        assert( n==pPage->pgno && e==PTRMAP_BTREE );
+      }
+    }
+    if( !pPage->leaf ){
+      Pgno child = get4byte(&pPage->aData[pPage->hdrOffset+8]);
+      ptrmapGet(pBt, child, &e, &n);
+      assert( n==pPage->pgno && e==PTRMAP_BTREE );
+    }
+  }
+  return 1;
+}
+#endif
+
+/*
+** This function is used to copy the contents of the b-tree node stored 
+** on page pFrom to page pTo. If page pFrom was not a leaf page, then
+** the pointer-map entries for each child page are updated so that the
+** parent page stored in the pointer map is page pTo. If pFrom contained
+** any cells with overflow page pointers, then the corresponding pointer
+** map entries are also updated so that the parent page is page pTo.
+**
+** If pFrom is currently carrying any overflow cells (entries in the
+** MemPage.apOvfl[] array), they are not copied to pTo. 
+**
+** Before returning, page pTo is reinitialized using btreeInitPage().
+**
+** The performance of this function is not critical. It is only used by 
+** the balance_shallower() and balance_deeper() procedures, neither of
+** which are called often under normal circumstances.
+*/
+static void copyNodeContent(MemPage *pFrom, MemPage *pTo, int *pRC){
+  if( (*pRC)==SQLITE_OK ){
+    BtShared * const pBt = pFrom->pBt;
+    u8 * const aFrom = pFrom->aData;
+    u8 * const aTo = pTo->aData;
+    int const iFromHdr = pFrom->hdrOffset;
+    int const iToHdr = ((pTo->pgno==1) ? 100 : 0);
+    int rc;
+    int iData;
+  
+  
+    assert( pFrom->isInit );
+    assert( pFrom->nFree>=iToHdr );
+    assert( get2byte(&aFrom[iFromHdr+5]) <= (int)pBt->usableSize );
+  
+    /* Copy the b-tree node content from page pFrom to page pTo. */
+    iData = get2byte(&aFrom[iFromHdr+5]);
+    memcpy(&aTo[iData], &aFrom[iData], pBt->usableSize-iData);
+    memcpy(&aTo[iToHdr], &aFrom[iFromHdr], pFrom->cellOffset + 2*pFrom->nCell);
+  
+    /* Reinitialize page pTo so that the contents of the MemPage structure
+    ** match the new data. The initialization of pTo can actually fail under
+    ** fairly obscure circumstances, even though it is a copy of initialized 
+    ** page pFrom.
+    */
+    pTo->isInit = 0;
+    rc = btreeInitPage(pTo);
+    if( rc!=SQLITE_OK ){
+      *pRC = rc;
+      return;
+    }
+  
+    /* If this is an auto-vacuum database, update the pointer-map entries
+    ** for any b-tree or overflow pages that pTo now contains the pointers to.
+    */
+    if( ISAUTOVACUUM ){
+      *pRC = setChildPtrmaps(pTo);
+    }
+  }
+}
+
+/*
+** This routine redistributes cells on the iParentIdx'th child of pParent
+** (hereafter "the page") and up to 2 siblings so that all pages have about the
+** same amount of free space. Usually a single sibling on either side of the
+** page are used in the balancing, though both siblings might come from one
+** side if the page is the first or last child of its parent. If the page 
+** has fewer than 2 siblings (something which can only happen if the page
+** is a root page or a child of a root page) then all available siblings
+** participate in the balancing.
+**
+** The number of siblings of the page might be increased or decreased by 
+** one or two in an effort to keep pages nearly full but not over full. 
+**
+** Note that when this routine is called, some of the cells on the page
+** might not actually be stored in MemPage.aData[]. This can happen
+** if the page is overfull. This routine ensures that all cells allocated
+** to the page and its siblings fit into MemPage.aData[] before returning.
+**
+** In the course of balancing the page and its siblings, cells may be
+** inserted into or removed from the parent page (pParent). Doing so
+** may cause the parent page to become overfull or underfull. If this
+** happens, it is the responsibility of the caller to invoke the correct
+** balancing routine to fix this problem (see the balance() routine). 
+**
+** If this routine fails for any reason, it might leave the database
+** in a corrupted state. So if this routine fails, the database should
+** be rolled back.
+**
+** The third argument to this function, aOvflSpace, is a pointer to a
+** buffer big enough to hold one page. If while inserting cells into the parent
+** page (pParent) the parent page becomes overfull, this buffer is
+** used to store the parent's overflow cells. Because this function inserts
+** a maximum of four divider cells into the parent page, and the maximum
+** size of a cell stored within an internal node is always less than 1/4
+** of the page-size, the aOvflSpace[] buffer is guaranteed to be large
+** enough for all overflow cells.
+**
+** If aOvflSpace is set to a null pointer, this function returns 
+** SQLITE_NOMEM.
+*/
+static int balance_nonroot(
+  MemPage *pParent,               /* Parent page of siblings being balanced */
+  int iParentIdx,                 /* Index of "the page" in pParent */
+  u8 *aOvflSpace,                 /* page-size bytes of space for parent ovfl */
+  int isRoot,                     /* True if pParent is a root-page */
+  int bBulk                       /* True if this call is part of a bulk load */
+){
+  BtShared *pBt;               /* The whole database */
+  int nMaxCells = 0;           /* Allocated size of apCell, szCell, aFrom. */
+  int nNew = 0;                /* Number of pages in apNew[] */
+  int nOld;                    /* Number of pages in apOld[] */
+  int i, j, k;                 /* Loop counters */
+  int nxDiv;                   /* Next divider slot in pParent->aCell[] */
+  int rc = SQLITE_OK;          /* The return code */
+  u16 leafCorrection;          /* 4 if pPage is a leaf.  0 if not */
+  int leafData;                /* True if pPage is a leaf of a LEAFDATA tree */
+  int usableSpace;             /* Bytes in pPage beyond the header */
+  int pageFlags;               /* Value of pPage->aData[0] */
+  int iSpace1 = 0;             /* First unused byte of aSpace1[] */
+  int iOvflSpace = 0;          /* First unused byte of aOvflSpace[] */
+  int szScratch;               /* Size of scratch memory requested */
+  MemPage *apOld[NB];          /* pPage and up to two siblings */
+  MemPage *apNew[NB+2];        /* pPage and up to NB siblings after balancing */
+  u8 *pRight;                  /* Location in parent of right-sibling pointer */
+  u8 *apDiv[NB-1];             /* Divider cells in pParent */
+  int cntNew[NB+2];            /* Index in b.paCell[] of cell after i-th page */
+  int cntOld[NB+2];            /* Old index in b.apCell[] */
+  int szNew[NB+2];             /* Combined size of cells placed on i-th page */
+  u8 *aSpace1;                 /* Space for copies of dividers cells */
+  Pgno pgno;                   /* Temp var to store a page number in */
+  u8 abDone[NB+2];             /* True after i'th new page is populated */
+  Pgno aPgno[NB+2];            /* Page numbers of new pages before shuffling */
+  Pgno aPgOrder[NB+2];         /* Copy of aPgno[] used for sorting pages */
+  u16 aPgFlags[NB+2];          /* flags field of new pages before shuffling */
+  CellArray b;                  /* Parsed information on cells being balanced */
+
+  memset(abDone, 0, sizeof(abDone));
+  b.nCell = 0;
+  b.apCell = 0;
+  pBt = pParent->pBt;
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( sqlite3PagerIswriteable(pParent->pDbPage) );
+
+#if 0
+  TRACE(("BALANCE: begin page %d child of %d\n", pPage->pgno, pParent->pgno));
+#endif
+
+  /* At this point pParent may have at most one overflow cell. And if
+  ** this overflow cell is present, it must be the cell with 
+  ** index iParentIdx. This scenario comes about when this function
+  ** is called (indirectly) from sqlite3BtreeDelete().
+  */
+  assert( pParent->nOverflow==0 || pParent->nOverflow==1 );
+  assert( pParent->nOverflow==0 || pParent->aiOvfl[0]==iParentIdx );
+
+  if( !aOvflSpace ){
+    return SQLITE_NOMEM_BKPT;
+  }
+
+  /* Find the sibling pages to balance. Also locate the cells in pParent 
+  ** that divide the siblings. An attempt is made to find NN siblings on 
+  ** either side of pPage. More siblings are taken from one side, however, 
+  ** if there are fewer than NN siblings on the other side. If pParent
+  ** has NB or fewer children then all children of pParent are taken.  
+  **
+  ** This loop also drops the divider cells from the parent page. This
+  ** way, the remainder of the function does not have to deal with any
+  ** overflow cells in the parent page, since if any existed they will
+  ** have already been removed.
+  */
+  i = pParent->nOverflow + pParent->nCell;
+  if( i<2 ){
+    nxDiv = 0;
+  }else{
+    assert( bBulk==0 || bBulk==1 );
+    if( iParentIdx==0 ){                 
+      nxDiv = 0;
+    }else if( iParentIdx==i ){
+      nxDiv = i-2+bBulk;
+    }else{
+      nxDiv = iParentIdx-1;
+    }
+    i = 2-bBulk;
+  }
+  nOld = i+1;
+  if( (i+nxDiv-pParent->nOverflow)==pParent->nCell ){
+    pRight = &pParent->aData[pParent->hdrOffset+8];
+  }else{
+    pRight = findCell(pParent, i+nxDiv-pParent->nOverflow);
+  }
+  pgno = get4byte(pRight);
+  while( 1 ){
+    rc = getAndInitPage(pBt, pgno, &apOld[i], 0, 0);
+    if( rc ){
+      memset(apOld, 0, (i+1)*sizeof(MemPage*));
+      goto balance_cleanup;
+    }
+    nMaxCells += 1+apOld[i]->nCell+apOld[i]->nOverflow;
+    if( (i--)==0 ) break;
+
+    if( i+nxDiv==pParent->aiOvfl[0] && pParent->nOverflow ){
+      apDiv[i] = pParent->apOvfl[0];
+      pgno = get4byte(apDiv[i]);
+      szNew[i] = pParent->xCellSize(pParent, apDiv[i]);
+      pParent->nOverflow = 0;
+    }else{
+      apDiv[i] = findCell(pParent, i+nxDiv-pParent->nOverflow);
+      pgno = get4byte(apDiv[i]);
+      szNew[i] = pParent->xCellSize(pParent, apDiv[i]);
+
+      /* Drop the cell from the parent page. apDiv[i] still points to
+      ** the cell within the parent, even though it has been dropped.
+      ** This is safe because dropping a cell only overwrites the first
+      ** four bytes of it, and this function does not need the first
+      ** four bytes of the divider cell. So the pointer is safe to use
+      ** later on.  
+      **
+      ** But not if we are in secure-delete mode. In secure-delete mode,
+      ** the dropCell() routine will overwrite the entire cell with zeroes.
+      ** In this case, temporarily copy the cell into the aOvflSpace[]
+      ** buffer. It will be copied out again as soon as the aSpace[] buffer
+      ** is allocated.  */
+      if( pBt->btsFlags & BTS_SECURE_DELETE ){
+        int iOff;
+
+        iOff = SQLITE_PTR_TO_INT(apDiv[i]) - SQLITE_PTR_TO_INT(pParent->aData);
+        if( (iOff+szNew[i])>(int)pBt->usableSize ){
+          rc = SQLITE_CORRUPT_BKPT;
+          memset(apOld, 0, (i+1)*sizeof(MemPage*));
+          goto balance_cleanup;
+        }else{
+          memcpy(&aOvflSpace[iOff], apDiv[i], szNew[i]);
+          apDiv[i] = &aOvflSpace[apDiv[i]-pParent->aData];
+        }
+      }
+      dropCell(pParent, i+nxDiv-pParent->nOverflow, szNew[i], &rc);
+    }
+  }
+
+  /* Make nMaxCells a multiple of 4 in order to preserve 8-byte
+  ** alignment */
+  nMaxCells = (nMaxCells + 3)&~3;
+
+  /*
+  ** Allocate space for memory structures
+  */
+  szScratch =
+       nMaxCells*sizeof(u8*)                       /* b.apCell */
+     + nMaxCells*sizeof(u16)                       /* b.szCell */
+     + pBt->pageSize;                              /* aSpace1 */
+
+  /* EVIDENCE-OF: R-28375-38319 SQLite will never request a scratch buffer
+  ** that is more than 6 times the database page size. */
+  assert( szScratch<=6*(int)pBt->pageSize );
+  b.apCell = sqlite3ScratchMalloc( szScratch ); 
+  if( b.apCell==0 ){
+    rc = SQLITE_NOMEM_BKPT;
+    goto balance_cleanup;
+  }
+  b.szCell = (u16*)&b.apCell[nMaxCells];
+  aSpace1 = (u8*)&b.szCell[nMaxCells];
+  assert( EIGHT_BYTE_ALIGNMENT(aSpace1) );
+
+  /*
+  ** Load pointers to all cells on sibling pages and the divider cells
+  ** into the local b.apCell[] array.  Make copies of the divider cells
+  ** into space obtained from aSpace1[]. The divider cells have already
+  ** been removed from pParent.
+  **
+  ** If the siblings are on leaf pages, then the child pointers of the
+  ** divider cells are stripped from the cells before they are copied
+  ** into aSpace1[].  In this way, all cells in b.apCell[] are without
+  ** child pointers.  If siblings are not leaves, then all cell in
+  ** b.apCell[] include child pointers.  Either way, all cells in b.apCell[]
+  ** are alike.
+  **
+  ** leafCorrection:  4 if pPage is a leaf.  0 if pPage is not a leaf.
+  **       leafData:  1 if pPage holds key+data and pParent holds only keys.
+  */
+  b.pRef = apOld[0];
+  leafCorrection = b.pRef->leaf*4;
+  leafData = b.pRef->intKeyLeaf;
+  for(i=0; i<nOld; i++){
+    MemPage *pOld = apOld[i];
+    int limit = pOld->nCell;
+    u8 *aData = pOld->aData;
+    u16 maskPage = pOld->maskPage;
+    u8 *piCell = aData + pOld->cellOffset;
+    u8 *piEnd;
+
+    /* Verify that all sibling pages are of the same "type" (table-leaf,
+    ** table-interior, index-leaf, or index-interior).
+    */
+    if( pOld->aData[0]!=apOld[0]->aData[0] ){
+      rc = SQLITE_CORRUPT_BKPT;
+      goto balance_cleanup;
+    }
+
+    /* Load b.apCell[] with pointers to all cells in pOld.  If pOld
+    ** constains overflow cells, include them in the b.apCell[] array
+    ** in the correct spot.
+    **
+    ** Note that when there are multiple overflow cells, it is always the
+    ** case that they are sequential and adjacent.  This invariant arises
+    ** because multiple overflows can only occurs when inserting divider
+    ** cells into a parent on a prior balance, and divider cells are always
+    ** adjacent and are inserted in order.  There is an assert() tagged
+    ** with "NOTE 1" in the overflow cell insertion loop to prove this
+    ** invariant.
+    **
+    ** This must be done in advance.  Once the balance starts, the cell
+    ** offset section of the btree page will be overwritten and we will no
+    ** long be able to find the cells if a pointer to each cell is not saved
+    ** first.
+    */
+    memset(&b.szCell[b.nCell], 0, sizeof(b.szCell[0])*(limit+pOld->nOverflow));
+    if( pOld->nOverflow>0 ){
+      limit = pOld->aiOvfl[0];
+      for(j=0; j<limit; j++){
+        b.apCell[b.nCell] = aData + (maskPage & get2byteAligned(piCell));
+        piCell += 2;
+        b.nCell++;
+      }
+      for(k=0; k<pOld->nOverflow; k++){
+        assert( k==0 || pOld->aiOvfl[k-1]+1==pOld->aiOvfl[k] );/* NOTE 1 */
+        b.apCell[b.nCell] = pOld->apOvfl[k];
+        b.nCell++;
+      }
+    }
+    piEnd = aData + pOld->cellOffset + 2*pOld->nCell;
+    while( piCell<piEnd ){
+      assert( b.nCell<nMaxCells );
+      b.apCell[b.nCell] = aData + (maskPage & get2byteAligned(piCell));
+      piCell += 2;
+      b.nCell++;
+    }
+
+    cntOld[i] = b.nCell;
+    if( i<nOld-1 && !leafData){
+      u16 sz = (u16)szNew[i];
+      u8 *pTemp;
+      assert( b.nCell<nMaxCells );
+      b.szCell[b.nCell] = sz;
+      pTemp = &aSpace1[iSpace1];
+      iSpace1 += sz;
+      assert( sz<=pBt->maxLocal+23 );
+      assert( iSpace1 <= (int)pBt->pageSize );
+      memcpy(pTemp, apDiv[i], sz);
+      b.apCell[b.nCell] = pTemp+leafCorrection;
+      assert( leafCorrection==0 || leafCorrection==4 );
+      b.szCell[b.nCell] = b.szCell[b.nCell] - leafCorrection;
+      if( !pOld->leaf ){
+        assert( leafCorrection==0 );
+        assert( pOld->hdrOffset==0 );
+        /* The right pointer of the child page pOld becomes the left
+        ** pointer of the divider cell */
+        memcpy(b.apCell[b.nCell], &pOld->aData[8], 4);
+      }else{
+        assert( leafCorrection==4 );
+        while( b.szCell[b.nCell]<4 ){
+          /* Do not allow any cells smaller than 4 bytes. If a smaller cell
+          ** does exist, pad it with 0x00 bytes. */
+          assert( b.szCell[b.nCell]==3 || CORRUPT_DB );
+          assert( b.apCell[b.nCell]==&aSpace1[iSpace1-3] || CORRUPT_DB );
+          aSpace1[iSpace1++] = 0x00;
+          b.szCell[b.nCell]++;
+        }
+      }
+      b.nCell++;
+    }
+  }
+
+  /*
+  ** Figure out the number of pages needed to hold all b.nCell cells.
+  ** Store this number in "k".  Also compute szNew[] which is the total
+  ** size of all cells on the i-th page and cntNew[] which is the index
+  ** in b.apCell[] of the cell that divides page i from page i+1.  
+  ** cntNew[k] should equal b.nCell.
+  **
+  ** Values computed by this block:
+  **
+  **           k: The total number of sibling pages
+  **    szNew[i]: Spaced used on the i-th sibling page.
+  **   cntNew[i]: Index in b.apCell[] and b.szCell[] for the first cell to
+  **              the right of the i-th sibling page.
+  ** usableSpace: Number of bytes of space available on each sibling.
+  ** 
+  */
+  usableSpace = pBt->usableSize - 12 + leafCorrection;
+  for(i=0; i<nOld; i++){
+    MemPage *p = apOld[i];
+    szNew[i] = usableSpace - p->nFree;
+    if( szNew[i]<0 ){ rc = SQLITE_CORRUPT_BKPT; goto balance_cleanup; }
+    for(j=0; j<p->nOverflow; j++){
+      szNew[i] += 2 + p->xCellSize(p, p->apOvfl[j]);
+    }
+    cntNew[i] = cntOld[i];
+  }
+  k = nOld;
+  for(i=0; i<k; i++){
+    int sz;
+    while( szNew[i]>usableSpace ){
+      if( i+1>=k ){
+        k = i+2;
+        if( k>NB+2 ){ rc = SQLITE_CORRUPT_BKPT; goto balance_cleanup; }
+        szNew[k-1] = 0;
+        cntNew[k-1] = b.nCell;
+      }
+      sz = 2 + cachedCellSize(&b, cntNew[i]-1);
+      szNew[i] -= sz;
+      if( !leafData ){
+        if( cntNew[i]<b.nCell ){
+          sz = 2 + cachedCellSize(&b, cntNew[i]);
+        }else{
+          sz = 0;
+        }
+      }
+      szNew[i+1] += sz;
+      cntNew[i]--;
+    }
+    while( cntNew[i]<b.nCell ){
+      sz = 2 + cachedCellSize(&b, cntNew[i]);
+      if( szNew[i]+sz>usableSpace ) break;
+      szNew[i] += sz;
+      cntNew[i]++;
+      if( !leafData ){
+        if( cntNew[i]<b.nCell ){
+          sz = 2 + cachedCellSize(&b, cntNew[i]);
+        }else{
+          sz = 0;
+        }
+      }
+      szNew[i+1] -= sz;
+    }
+    if( cntNew[i]>=b.nCell ){
+      k = i+1;
+    }else if( cntNew[i] <= (i>0 ? cntNew[i-1] : 0) ){
+      rc = SQLITE_CORRUPT_BKPT;
+      goto balance_cleanup;
+    }
+  }
+
+  /*
+  ** The packing computed by the previous block is biased toward the siblings
+  ** on the left side (siblings with smaller keys). The left siblings are
+  ** always nearly full, while the right-most sibling might be nearly empty.
+  ** The next block of code attempts to adjust the packing of siblings to
+  ** get a better balance.
+  **
+  ** This adjustment is more than an optimization.  The packing above might
+  ** be so out of balance as to be illegal.  For example, the right-most
+  ** sibling might be completely empty.  This adjustment is not optional.
+  */
+  for(i=k-1; i>0; i--){
+    int szRight = szNew[i];  /* Size of sibling on the right */
+    int szLeft = szNew[i-1]; /* Size of sibling on the left */
+    int r;              /* Index of right-most cell in left sibling */
+    int d;              /* Index of first cell to the left of right sibling */
+
+    r = cntNew[i-1] - 1;
+    d = r + 1 - leafData;
+    (void)cachedCellSize(&b, d);
+    do{
+      assert( d<nMaxCells );
+      assert( r<nMaxCells );
+      (void)cachedCellSize(&b, r);
+      if( szRight!=0
+       && (bBulk || szRight+b.szCell[d]+2 > szLeft-(b.szCell[r]+(i==k-1?0:2)))){
+        break;
+      }
+      szRight += b.szCell[d] + 2;
+      szLeft -= b.szCell[r] + 2;
+      cntNew[i-1] = r;
+      r--;
+      d--;
+    }while( r>=0 );
+    szNew[i] = szRight;
+    szNew[i-1] = szLeft;
+    if( cntNew[i-1] <= (i>1 ? cntNew[i-2] : 0) ){
+      rc = SQLITE_CORRUPT_BKPT;
+      goto balance_cleanup;
+    }
+  }
+
+  /* Sanity check:  For a non-corrupt database file one of the follwing
+  ** must be true:
+  **    (1) We found one or more cells (cntNew[0])>0), or
+  **    (2) pPage is a virtual root page.  A virtual root page is when
+  **        the real root page is page 1 and we are the only child of
+  **        that page.
+  */
+  assert( cntNew[0]>0 || (pParent->pgno==1 && pParent->nCell==0) || CORRUPT_DB);
+  TRACE(("BALANCE: old: %d(nc=%d) %d(nc=%d) %d(nc=%d)\n",
+    apOld[0]->pgno, apOld[0]->nCell,
+    nOld>=2 ? apOld[1]->pgno : 0, nOld>=2 ? apOld[1]->nCell : 0,
+    nOld>=3 ? apOld[2]->pgno : 0, nOld>=3 ? apOld[2]->nCell : 0
+  ));
+
+  /*
+  ** Allocate k new pages.  Reuse old pages where possible.
+  */
+  pageFlags = apOld[0]->aData[0];
+  for(i=0; i<k; i++){
+    MemPage *pNew;
+    if( i<nOld ){
+      pNew = apNew[i] = apOld[i];
+      apOld[i] = 0;
+      rc = sqlite3PagerWrite(pNew->pDbPage);
+      nNew++;
+      if( rc ) goto balance_cleanup;
+    }else{
+      assert( i>0 );
+      rc = allocateBtreePage(pBt, &pNew, &pgno, (bBulk ? 1 : pgno), 0);
+      if( rc ) goto balance_cleanup;
+      zeroPage(pNew, pageFlags);
+      apNew[i] = pNew;
+      nNew++;
+      cntOld[i] = b.nCell;
+
+      /* Set the pointer-map entry for the new sibling page. */
+      if( ISAUTOVACUUM ){
+        ptrmapPut(pBt, pNew->pgno, PTRMAP_BTREE, pParent->pgno, &rc);
+        if( rc!=SQLITE_OK ){
+          goto balance_cleanup;
+        }
+      }
+    }
+  }
+
+  /*
+  ** Reassign page numbers so that the new pages are in ascending order. 
+  ** This helps to keep entries in the disk file in order so that a scan
+  ** of the table is closer to a linear scan through the file. That in turn 
+  ** helps the operating system to deliver pages from the disk more rapidly.
+  **
+  ** An O(n^2) insertion sort algorithm is used, but since n is never more 
+  ** than (NB+2) (a small constant), that should not be a problem.
+  **
+  ** When NB==3, this one optimization makes the database about 25% faster 
+  ** for large insertions and deletions.
+  */
+  for(i=0; i<nNew; i++){
+    aPgOrder[i] = aPgno[i] = apNew[i]->pgno;
+    aPgFlags[i] = apNew[i]->pDbPage->flags;
+    for(j=0; j<i; j++){
+      if( aPgno[j]==aPgno[i] ){
+        /* This branch is taken if the set of sibling pages somehow contains
+        ** duplicate entries. This can happen if the database is corrupt. 
+        ** It would be simpler to detect this as part of the loop below, but
+        ** we do the detection here in order to avoid populating the pager
+        ** cache with two separate objects associated with the same
+        ** page number.  */
+        assert( CORRUPT_DB );
+        rc = SQLITE_CORRUPT_BKPT;
+        goto balance_cleanup;
+      }
+    }
+  }
+  for(i=0; i<nNew; i++){
+    int iBest = 0;                /* aPgno[] index of page number to use */
+    for(j=1; j<nNew; j++){
+      if( aPgOrder[j]<aPgOrder[iBest] ) iBest = j;
+    }
+    pgno = aPgOrder[iBest];
+    aPgOrder[iBest] = 0xffffffff;
+    if( iBest!=i ){
+      if( iBest>i ){
+        sqlite3PagerRekey(apNew[iBest]->pDbPage, pBt->nPage+iBest+1, 0);
+      }
+      sqlite3PagerRekey(apNew[i]->pDbPage, pgno, aPgFlags[iBest]);
+      apNew[i]->pgno = pgno;
+    }
+  }
+
+  TRACE(("BALANCE: new: %d(%d nc=%d) %d(%d nc=%d) %d(%d nc=%d) "
+         "%d(%d nc=%d) %d(%d nc=%d)\n",
+    apNew[0]->pgno, szNew[0], cntNew[0],
+    nNew>=2 ? apNew[1]->pgno : 0, nNew>=2 ? szNew[1] : 0,
+    nNew>=2 ? cntNew[1] - cntNew[0] - !leafData : 0,
+    nNew>=3 ? apNew[2]->pgno : 0, nNew>=3 ? szNew[2] : 0,
+    nNew>=3 ? cntNew[2] - cntNew[1] - !leafData : 0,
+    nNew>=4 ? apNew[3]->pgno : 0, nNew>=4 ? szNew[3] : 0,
+    nNew>=4 ? cntNew[3] - cntNew[2] - !leafData : 0,
+    nNew>=5 ? apNew[4]->pgno : 0, nNew>=5 ? szNew[4] : 0,
+    nNew>=5 ? cntNew[4] - cntNew[3] - !leafData : 0
+  ));
+
+  assert( sqlite3PagerIswriteable(pParent->pDbPage) );
+  put4byte(pRight, apNew[nNew-1]->pgno);
+
+  /* If the sibling pages are not leaves, ensure that the right-child pointer
+  ** of the right-most new sibling page is set to the value that was 
+  ** originally in the same field of the right-most old sibling page. */
+  if( (pageFlags & PTF_LEAF)==0 && nOld!=nNew ){
+    MemPage *pOld = (nNew>nOld ? apNew : apOld)[nOld-1];
+    memcpy(&apNew[nNew-1]->aData[8], &pOld->aData[8], 4);
+  }
+
+  /* Make any required updates to pointer map entries associated with 
+  ** cells stored on sibling pages following the balance operation. Pointer
+  ** map entries associated with divider cells are set by the insertCell()
+  ** routine. The associated pointer map entries are:
+  **
+  **   a) if the cell contains a reference to an overflow chain, the
+  **      entry associated with the first page in the overflow chain, and
+  **
+  **   b) if the sibling pages are not leaves, the child page associated
+  **      with the cell.
+  **
+  ** If the sibling pages are not leaves, then the pointer map entry 
+  ** associated with the right-child of each sibling may also need to be 
+  ** updated. This happens below, after the sibling pages have been 
+  ** populated, not here.
+  */
+  if( ISAUTOVACUUM ){
+    MemPage *pNew = apNew[0];
+    u8 *aOld = pNew->aData;
+    int cntOldNext = pNew->nCell + pNew->nOverflow;
+    int usableSize = pBt->usableSize;
+    int iNew = 0;
+    int iOld = 0;
+
+    for(i=0; i<b.nCell; i++){
+      u8 *pCell = b.apCell[i];
+      if( i==cntOldNext ){
+        MemPage *pOld = (++iOld)<nNew ? apNew[iOld] : apOld[iOld];
+        cntOldNext += pOld->nCell + pOld->nOverflow + !leafData;
+        aOld = pOld->aData;
+      }
+      if( i==cntNew[iNew] ){
+        pNew = apNew[++iNew];
+        if( !leafData ) continue;
+      }
+
+      /* Cell pCell is destined for new sibling page pNew. Originally, it
+      ** was either part of sibling page iOld (possibly an overflow cell), 
+      ** or else the divider cell to the left of sibling page iOld. So,
+      ** if sibling page iOld had the same page number as pNew, and if
+      ** pCell really was a part of sibling page iOld (not a divider or
+      ** overflow cell), we can skip updating the pointer map entries.  */
+      if( iOld>=nNew
+       || pNew->pgno!=aPgno[iOld]
+       || !SQLITE_WITHIN(pCell,aOld,&aOld[usableSize])
+      ){
+        if( !leafCorrection ){
+          ptrmapPut(pBt, get4byte(pCell), PTRMAP_BTREE, pNew->pgno, &rc);
+        }
+        if( cachedCellSize(&b,i)>pNew->minLocal ){
+          ptrmapPutOvflPtr(pNew, pCell, &rc);
+        }
+        if( rc ) goto balance_cleanup;
+      }
+    }
+  }
+
+  /* Insert new divider cells into pParent. */
+  for(i=0; i<nNew-1; i++){
+    u8 *pCell;
+    u8 *pTemp;
+    int sz;
+    MemPage *pNew = apNew[i];
+    j = cntNew[i];
+
+    assert( j<nMaxCells );
+    assert( b.apCell[j]!=0 );
+    pCell = b.apCell[j];
+    sz = b.szCell[j] + leafCorrection;
+    pTemp = &aOvflSpace[iOvflSpace];
+    if( !pNew->leaf ){
+      memcpy(&pNew->aData[8], pCell, 4);
+    }else if( leafData ){
+      /* If the tree is a leaf-data tree, and the siblings are leaves, 
+      ** then there is no divider cell in b.apCell[]. Instead, the divider 
+      ** cell consists of the integer key for the right-most cell of 
+      ** the sibling-page assembled above only.
+      */
+      CellInfo info;
+      j--;
+      pNew->xParseCell(pNew, b.apCell[j], &info);
+      pCell = pTemp;
+      sz = 4 + putVarint(&pCell[4], info.nKey);
+      pTemp = 0;
+    }else{
+      pCell -= 4;
+      /* Obscure case for non-leaf-data trees: If the cell at pCell was
+      ** previously stored on a leaf node, and its reported size was 4
+      ** bytes, then it may actually be smaller than this 
+      ** (see btreeParseCellPtr(), 4 bytes is the minimum size of
+      ** any cell). But it is important to pass the correct size to 
+      ** insertCell(), so reparse the cell now.
+      **
+      ** This can only happen for b-trees used to evaluate "IN (SELECT ...)"
+      ** and WITHOUT ROWID tables with exactly one column which is the
+      ** primary key.
+      */
+      if( b.szCell[j]==4 ){
+        assert(leafCorrection==4);
+        sz = pParent->xCellSize(pParent, pCell);
+      }
+    }
+    iOvflSpace += sz;
+    assert( sz<=pBt->maxLocal+23 );
+    assert( iOvflSpace <= (int)pBt->pageSize );
+    insertCell(pParent, nxDiv+i, pCell, sz, pTemp, pNew->pgno, &rc);
+    if( rc!=SQLITE_OK ) goto balance_cleanup;
+    assert( sqlite3PagerIswriteable(pParent->pDbPage) );
+  }
+
+  /* Now update the actual sibling pages. The order in which they are updated
+  ** is important, as this code needs to avoid disrupting any page from which
+  ** cells may still to be read. In practice, this means:
+  **
+  **  (1) If cells are moving left (from apNew[iPg] to apNew[iPg-1])
+  **      then it is not safe to update page apNew[iPg] until after
+  **      the left-hand sibling apNew[iPg-1] has been updated.
+  **
+  **  (2) If cells are moving right (from apNew[iPg] to apNew[iPg+1])
+  **      then it is not safe to update page apNew[iPg] until after
+  **      the right-hand sibling apNew[iPg+1] has been updated.
+  **
+  ** If neither of the above apply, the page is safe to update.
+  **
+  ** The iPg value in the following loop starts at nNew-1 goes down
+  ** to 0, then back up to nNew-1 again, thus making two passes over
+  ** the pages.  On the initial downward pass, only condition (1) above
+  ** needs to be tested because (2) will always be true from the previous
+  ** step.  On the upward pass, both conditions are always true, so the
+  ** upwards pass simply processes pages that were missed on the downward
+  ** pass.
+  */
+  for(i=1-nNew; i<nNew; i++){
+    int iPg = i<0 ? -i : i;
+    assert( iPg>=0 && iPg<nNew );
+    if( abDone[iPg] ) continue;         /* Skip pages already processed */
+    if( i>=0                            /* On the upwards pass, or... */
+     || cntOld[iPg-1]>=cntNew[iPg-1]    /* Condition (1) is true */
+    ){
+      int iNew;
+      int iOld;
+      int nNewCell;
+
+      /* Verify condition (1):  If cells are moving left, update iPg
+      ** only after iPg-1 has already been updated. */
+      assert( iPg==0 || cntOld[iPg-1]>=cntNew[iPg-1] || abDone[iPg-1] );
+
+      /* Verify condition (2):  If cells are moving right, update iPg
+      ** only after iPg+1 has already been updated. */
+      assert( cntNew[iPg]>=cntOld[iPg] || abDone[iPg+1] );
+
+      if( iPg==0 ){
+        iNew = iOld = 0;
+        nNewCell = cntNew[0];
+      }else{
+        iOld = iPg<nOld ? (cntOld[iPg-1] + !leafData) : b.nCell;
+        iNew = cntNew[iPg-1] + !leafData;
+        nNewCell = cntNew[iPg] - iNew;
+      }
+
+      rc = editPage(apNew[iPg], iOld, iNew, nNewCell, &b);
+      if( rc ) goto balance_cleanup;
+      abDone[iPg]++;
+      apNew[iPg]->nFree = usableSpace-szNew[iPg];
+      assert( apNew[iPg]->nOverflow==0 );
+      assert( apNew[iPg]->nCell==nNewCell );
+    }
+  }
+
+  /* All pages have been processed exactly once */
+  assert( memcmp(abDone, "\01\01\01\01\01", nNew)==0 );
+
+  assert( nOld>0 );
+  assert( nNew>0 );
+
+  if( isRoot && pParent->nCell==0 && pParent->hdrOffset<=apNew[0]->nFree ){
+    /* The root page of the b-tree now contains no cells. The only sibling
+    ** page is the right-child of the parent. Copy the contents of the
+    ** child page into the parent, decreasing the overall height of the
+    ** b-tree structure by one. This is described as the "balance-shallower"
+    ** sub-algorithm in some documentation.
+    **
+    ** If this is an auto-vacuum database, the call to copyNodeContent() 
+    ** sets all pointer-map entries corresponding to database image pages 
+    ** for which the pointer is stored within the content being copied.
+    **
+    ** It is critical that the child page be defragmented before being
+    ** copied into the parent, because if the parent is page 1 then it will
+    ** by smaller than the child due to the database header, and so all the
+    ** free space needs to be up front.
+    */
+    assert( nNew==1 || CORRUPT_DB );
+    rc = defragmentPage(apNew[0]);
+    testcase( rc!=SQLITE_OK );
+    assert( apNew[0]->nFree == 
+        (get2byte(&apNew[0]->aData[5])-apNew[0]->cellOffset-apNew[0]->nCell*2)
+      || rc!=SQLITE_OK
+    );
+    copyNodeContent(apNew[0], pParent, &rc);
+    freePage(apNew[0], &rc);
+  }else if( ISAUTOVACUUM && !leafCorrection ){
+    /* Fix the pointer map entries associated with the right-child of each
+    ** sibling page. All other pointer map entries have already been taken
+    ** care of.  */
+    for(i=0; i<nNew; i++){
+      u32 key = get4byte(&apNew[i]->aData[8]);
+      ptrmapPut(pBt, key, PTRMAP_BTREE, apNew[i]->pgno, &rc);
+    }
+  }
+
+  assert( pParent->isInit );
+  TRACE(("BALANCE: finished: old=%d new=%d cells=%d\n",
+          nOld, nNew, b.nCell));
+
+  /* Free any old pages that were not reused as new pages.
+  */
+  for(i=nNew; i<nOld; i++){
+    freePage(apOld[i], &rc);
+  }
+
+#if 0
+  if( ISAUTOVACUUM && rc==SQLITE_OK && apNew[0]->isInit ){
+    /* The ptrmapCheckPages() contains assert() statements that verify that
+    ** all pointer map pages are set correctly. This is helpful while 
+    ** debugging. This is usually disabled because a corrupt database may
+    ** cause an assert() statement to fail.  */
+    ptrmapCheckPages(apNew, nNew);
+    ptrmapCheckPages(&pParent, 1);
+  }
+#endif
+
+  /*
+  ** Cleanup before returning.
+  */
+balance_cleanup:
+  sqlite3ScratchFree(b.apCell);
+  for(i=0; i<nOld; i++){
+    releasePage(apOld[i]);
+  }
+  for(i=0; i<nNew; i++){
+    releasePage(apNew[i]);
+  }
+
+  return rc;
+}
+
+
+/*
+** This function is called when the root page of a b-tree structure is
+** overfull (has one or more overflow pages).
+**
+** A new child page is allocated and the contents of the current root
+** page, including overflow cells, are copied into the child. The root
+** page is then overwritten to make it an empty page with the right-child 
+** pointer pointing to the new page.
+**
+** Before returning, all pointer-map entries corresponding to pages 
+** that the new child-page now contains pointers to are updated. The
+** entry corresponding to the new right-child pointer of the root
+** page is also updated.
+**
+** If successful, *ppChild is set to contain a reference to the child 
+** page and SQLITE_OK is returned. In this case the caller is required
+** to call releasePage() on *ppChild exactly once. If an error occurs,
+** an error code is returned and *ppChild is set to 0.
+*/
+static int balance_deeper(MemPage *pRoot, MemPage **ppChild){
+  int rc;                        /* Return value from subprocedures */
+  MemPage *pChild = 0;           /* Pointer to a new child page */
+  Pgno pgnoChild = 0;            /* Page number of the new child page */
+  BtShared *pBt = pRoot->pBt;    /* The BTree */
+
+  assert( pRoot->nOverflow>0 );
+  assert( sqlite3_mutex_held(pBt->mutex) );
+
+  /* Make pRoot, the root page of the b-tree, writable. Allocate a new 
+  ** page that will become the new right-child of pPage. Copy the contents
+  ** of the node stored on pRoot into the new child page.
+  */
+  rc = sqlite3PagerWrite(pRoot->pDbPage);
+  if( rc==SQLITE_OK ){
+    rc = allocateBtreePage(pBt,&pChild,&pgnoChild,pRoot->pgno,0);
+    copyNodeContent(pRoot, pChild, &rc);
+    if( ISAUTOVACUUM ){
+      ptrmapPut(pBt, pgnoChild, PTRMAP_BTREE, pRoot->pgno, &rc);
+    }
+  }
+  if( rc ){
+    *ppChild = 0;
+    releasePage(pChild);
+    return rc;
+  }
+  assert( sqlite3PagerIswriteable(pChild->pDbPage) );
+  assert( sqlite3PagerIswriteable(pRoot->pDbPage) );
+  assert( pChild->nCell==pRoot->nCell );
+
+  TRACE(("BALANCE: copy root %d into %d\n", pRoot->pgno, pChild->pgno));
+
+  /* Copy the overflow cells from pRoot to pChild */
+  memcpy(pChild->aiOvfl, pRoot->aiOvfl,
+         pRoot->nOverflow*sizeof(pRoot->aiOvfl[0]));
+  memcpy(pChild->apOvfl, pRoot->apOvfl,
+         pRoot->nOverflow*sizeof(pRoot->apOvfl[0]));
+  pChild->nOverflow = pRoot->nOverflow;
+
+  /* Zero the contents of pRoot. Then install pChild as the right-child. */
+  zeroPage(pRoot, pChild->aData[0] & ~PTF_LEAF);
+  put4byte(&pRoot->aData[pRoot->hdrOffset+8], pgnoChild);
+
+  *ppChild = pChild;
+  return SQLITE_OK;
+}
+
+/*
+** The page that pCur currently points to has just been modified in
+** some way. This function figures out if this modification means the
+** tree needs to be balanced, and if so calls the appropriate balancing 
+** routine. Balancing routines are:
+**
+**   balance_quick()
+**   balance_deeper()
+**   balance_nonroot()
+*/
+static int balance(BtCursor *pCur){
+  int rc = SQLITE_OK;
+  const int nMin = pCur->pBt->usableSize * 2 / 3;
+  u8 aBalanceQuickSpace[13];
+  u8 *pFree = 0;
+
+  VVA_ONLY( int balance_quick_called = 0 );
+  VVA_ONLY( int balance_deeper_called = 0 );
+
+  do {
+    int iPage = pCur->iPage;
+    MemPage *pPage = pCur->apPage[iPage];
+
+    if( iPage==0 ){
+      if( pPage->nOverflow ){
+        /* The root page of the b-tree is overfull. In this case call the
+        ** balance_deeper() function to create a new child for the root-page
+        ** and copy the current contents of the root-page to it. The
+        ** next iteration of the do-loop will balance the child page.
+        */ 
+        assert( balance_deeper_called==0 );
+        VVA_ONLY( balance_deeper_called++ );
+        rc = balance_deeper(pPage, &pCur->apPage[1]);
+        if( rc==SQLITE_OK ){
+          pCur->iPage = 1;
+          pCur->aiIdx[0] = 0;
+          pCur->aiIdx[1] = 0;
+          assert( pCur->apPage[1]->nOverflow );
+        }
+      }else{
+        break;
+      }
+    }else if( pPage->nOverflow==0 && pPage->nFree<=nMin ){
+      break;
+    }else{
+      MemPage * const pParent = pCur->apPage[iPage-1];
+      int const iIdx = pCur->aiIdx[iPage-1];
+
+      rc = sqlite3PagerWrite(pParent->pDbPage);
+      if( rc==SQLITE_OK ){
+#ifndef SQLITE_OMIT_QUICKBALANCE
+        if( pPage->intKeyLeaf
+         && pPage->nOverflow==1
+         && pPage->aiOvfl[0]==pPage->nCell
+         && pParent->pgno!=1
+         && pParent->nCell==iIdx
+        ){
+          /* Call balance_quick() to create a new sibling of pPage on which
+          ** to store the overflow cell. balance_quick() inserts a new cell
+          ** into pParent, which may cause pParent overflow. If this
+          ** happens, the next iteration of the do-loop will balance pParent 
+          ** use either balance_nonroot() or balance_deeper(). Until this
+          ** happens, the overflow cell is stored in the aBalanceQuickSpace[]
+          ** buffer. 
+          **
+          ** The purpose of the following assert() is to check that only a
+          ** single call to balance_quick() is made for each call to this
+          ** function. If this were not verified, a subtle bug involving reuse
+          ** of the aBalanceQuickSpace[] might sneak in.
+          */
+          assert( balance_quick_called==0 ); 
+          VVA_ONLY( balance_quick_called++ );
+          rc = balance_quick(pParent, pPage, aBalanceQuickSpace);
+        }else
+#endif
+        {
+          /* In this case, call balance_nonroot() to redistribute cells
+          ** between pPage and up to 2 of its sibling pages. This involves
+          ** modifying the contents of pParent, which may cause pParent to
+          ** become overfull or underfull. The next iteration of the do-loop
+          ** will balance the parent page to correct this.
+          ** 
+          ** If the parent page becomes overfull, the overflow cell or cells
+          ** are stored in the pSpace buffer allocated immediately below. 
+          ** A subsequent iteration of the do-loop will deal with this by
+          ** calling balance_nonroot() (balance_deeper() may be called first,
+          ** but it doesn't deal with overflow cells - just moves them to a
+          ** different page). Once this subsequent call to balance_nonroot() 
+          ** has completed, it is safe to release the pSpace buffer used by
+          ** the previous call, as the overflow cell data will have been 
+          ** copied either into the body of a database page or into the new
+          ** pSpace buffer passed to the latter call to balance_nonroot().
+          */
+          u8 *pSpace = sqlite3PageMalloc(pCur->pBt->pageSize);
+          rc = balance_nonroot(pParent, iIdx, pSpace, iPage==1,
+                               pCur->hints&BTREE_BULKLOAD);
+          if( pFree ){
+            /* If pFree is not NULL, it points to the pSpace buffer used 
+            ** by a previous call to balance_nonroot(). Its contents are
+            ** now stored either on real database pages or within the 
+            ** new pSpace buffer, so it may be safely freed here. */
+            sqlite3PageFree(pFree);
+          }
+
+          /* The pSpace buffer will be freed after the next call to
+          ** balance_nonroot(), or just before this function returns, whichever
+          ** comes first. */
+          pFree = pSpace;
+        }
+      }
+
+      pPage->nOverflow = 0;
+
+      /* The next iteration of the do-loop balances the parent page. */
+      releasePage(pPage);
+      pCur->iPage--;
+      assert( pCur->iPage>=0 );
+    }
+  }while( rc==SQLITE_OK );
+
+  if( pFree ){
+    sqlite3PageFree(pFree);
+  }
+  return rc;
+}
+
+
+/*
+** Insert a new record into the BTree.  The content of the new record
+** is described by the pX object.  The pCur cursor is used only to
+** define what table the record should be inserted into, and is left
+** pointing at a random location.
+**
+** For a table btree (used for rowid tables), only the pX.nKey value of
+** the key is used. The pX.pKey value must be NULL.  The pX.nKey is the
+** rowid or INTEGER PRIMARY KEY of the row.  The pX.nData,pData,nZero fields
+** hold the content of the row.
+**
+** For an index btree (used for indexes and WITHOUT ROWID tables), the
+** key is an arbitrary byte sequence stored in pX.pKey,nKey.  The 
+** pX.pData,nData,nZero fields must be zero.
+**
+** If the seekResult parameter is non-zero, then a successful call to
+** MovetoUnpacked() to seek cursor pCur to (pKey, nKey) has already
+** been performed. seekResult is the search result returned (a negative
+** number if pCur points at an entry that is smaller than (pKey, nKey), or
+** a positive value if pCur points at an entry that is larger than 
+** (pKey, nKey)). 
+**
+** If the seekResult parameter is non-zero, then the caller guarantees that
+** cursor pCur is pointing at the existing copy of a row that is to be
+** overwritten.  If the seekResult parameter is 0, then cursor pCur may
+** point to any entry or to no entry at all and so this function has to seek
+** the cursor before the new key can be inserted.
+*/
+SQLITE_PRIVATE int sqlite3BtreeInsert(
+  BtCursor *pCur,                /* Insert data into the table of this cursor */
+  const BtreePayload *pX,        /* Content of the row to be inserted */
+  int appendBias,                /* True if this is likely an append */
+  int seekResult                 /* Result of prior MovetoUnpacked() call */
+){
+  int rc;
+  int loc = seekResult;          /* -1: before desired location  +1: after */
+  int szNew = 0;
+  int idx;
+  MemPage *pPage;
+  Btree *p = pCur->pBtree;
+  BtShared *pBt = p->pBt;
+  unsigned char *oldCell;
+  unsigned char *newCell = 0;
+
+  if( pCur->eState==CURSOR_FAULT ){
+    assert( pCur->skipNext!=SQLITE_OK );
+    return pCur->skipNext;
+  }
+
+  assert( cursorOwnsBtShared(pCur) );
+  assert( (pCur->curFlags & BTCF_WriteFlag)!=0
+              && pBt->inTransaction==TRANS_WRITE
+              && (pBt->btsFlags & BTS_READ_ONLY)==0 );
+  assert( hasSharedCacheTableLock(p, pCur->pgnoRoot, pCur->pKeyInfo!=0, 2) );
+
+  /* Assert that the caller has been consistent. If this cursor was opened
+  ** expecting an index b-tree, then the caller should be inserting blob
+  ** keys with no associated data. If the cursor was opened expecting an
+  ** intkey table, the caller should be inserting integer keys with a
+  ** blob of associated data.  */
+  assert( (pX->pKey==0)==(pCur->pKeyInfo==0) );
+
+  /* Save the positions of any other cursors open on this table.
+  **
+  ** In some cases, the call to btreeMoveto() below is a no-op. For
+  ** example, when inserting data into a table with auto-generated integer
+  ** keys, the VDBE layer invokes sqlite3BtreeLast() to figure out the 
+  ** integer key to use. It then calls this function to actually insert the 
+  ** data into the intkey B-Tree. In this case btreeMoveto() recognizes
+  ** that the cursor is already where it needs to be and returns without
+  ** doing any work. To avoid thwarting these optimizations, it is important
+  ** not to clear the cursor here.
+  */
+  if( pCur->curFlags & BTCF_Multiple ){
+    rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur);
+    if( rc ) return rc;
+  }
+
+  if( pCur->pKeyInfo==0 ){
+    assert( pX->pKey==0 );
+    /* If this is an insert into a table b-tree, invalidate any incrblob 
+    ** cursors open on the row being replaced */
+    invalidateIncrblobCursors(p, pX->nKey, 0);
+
+    /* If the cursor is currently on the last row and we are appending a
+    ** new row onto the end, set the "loc" to avoid an unnecessary
+    ** btreeMoveto() call */
+    if( (pCur->curFlags&BTCF_ValidNKey)!=0 && pX->nKey>0
+      && pCur->info.nKey==pX->nKey-1 ){
+       loc = -1;
+    }else if( loc==0 ){
+      rc = sqlite3BtreeMovetoUnpacked(pCur, 0, pX->nKey, appendBias, &loc);
+      if( rc ) return rc;
+    }
+  }else if( loc==0 ){
+    rc = btreeMoveto(pCur, pX->pKey, pX->nKey, appendBias, &loc);
+    if( rc ) return rc;
+  }
+  assert( pCur->eState==CURSOR_VALID || (pCur->eState==CURSOR_INVALID && loc) );
+
+  pPage = pCur->apPage[pCur->iPage];
+  assert( pPage->intKey || pX->nKey>=0 );
+  assert( pPage->leaf || !pPage->intKey );
+
+  TRACE(("INSERT: table=%d nkey=%lld ndata=%d page=%d %s\n",
+          pCur->pgnoRoot, pX->nKey, pX->nData, pPage->pgno,
+          loc==0 ? "overwrite" : "new entry"));
+  assert( pPage->isInit );
+  newCell = pBt->pTmpSpace;
+  assert( newCell!=0 );
+  rc = fillInCell(pPage, newCell, pX, &szNew);
+  if( rc ) goto end_insert;
+  assert( szNew==pPage->xCellSize(pPage, newCell) );
+  assert( szNew <= MX_CELL_SIZE(pBt) );
+  idx = pCur->aiIdx[pCur->iPage];
+  if( loc==0 ){
+    u16 szOld;
+    assert( idx<pPage->nCell );
+    rc = sqlite3PagerWrite(pPage->pDbPage);
+    if( rc ){
+      goto end_insert;
+    }
+    oldCell = findCell(pPage, idx);
+    if( !pPage->leaf ){
+      memcpy(newCell, oldCell, 4);
+    }
+    rc = clearCell(pPage, oldCell, &szOld);
+    dropCell(pPage, idx, szOld, &rc);
+    if( rc ) goto end_insert;
+  }else if( loc<0 && pPage->nCell>0 ){
+    assert( pPage->leaf );
+    idx = ++pCur->aiIdx[pCur->iPage];
+  }else{
+    assert( pPage->leaf );
+  }
+  insertCell(pPage, idx, newCell, szNew, 0, 0, &rc);
+  assert( pPage->nOverflow==0 || rc==SQLITE_OK );
+  assert( rc!=SQLITE_OK || pPage->nCell>0 || pPage->nOverflow>0 );
+
+  /* If no error has occurred and pPage has an overflow cell, call balance() 
+  ** to redistribute the cells within the tree. Since balance() may move
+  ** the cursor, zero the BtCursor.info.nSize and BTCF_ValidNKey
+  ** variables.
+  **
+  ** Previous versions of SQLite called moveToRoot() to move the cursor
+  ** back to the root page as balance() used to invalidate the contents
+  ** of BtCursor.apPage[] and BtCursor.aiIdx[]. Instead of doing that,
+  ** set the cursor state to "invalid". This makes common insert operations
+  ** slightly faster.
+  **
+  ** There is a subtle but important optimization here too. When inserting
+  ** multiple records into an intkey b-tree using a single cursor (as can
+  ** happen while processing an "INSERT INTO ... SELECT" statement), it
+  ** is advantageous to leave the cursor pointing to the last entry in
+  ** the b-tree if possible. If the cursor is left pointing to the last
+  ** entry in the table, and the next row inserted has an integer key
+  ** larger than the largest existing key, it is possible to insert the
+  ** row without seeking the cursor. This can be a big performance boost.
+  */
+  pCur->info.nSize = 0;
+  if( pPage->nOverflow ){
+    assert( rc==SQLITE_OK );
+    pCur->curFlags &= ~(BTCF_ValidNKey);
+    rc = balance(pCur);
+
+    /* Must make sure nOverflow is reset to zero even if the balance()
+    ** fails. Internal data structure corruption will result otherwise. 
+    ** Also, set the cursor state to invalid. This stops saveCursorPosition()
+    ** from trying to save the current position of the cursor.  */
+    pCur->apPage[pCur->iPage]->nOverflow = 0;
+    pCur->eState = CURSOR_INVALID;
+  }
+  assert( pCur->apPage[pCur->iPage]->nOverflow==0 );
+
+end_insert:
+  return rc;
+}
+
+/*
+** Delete the entry that the cursor is pointing to. 
+**
+** If the BTREE_SAVEPOSITION bit of the flags parameter is zero, then
+** the cursor is left pointing at an arbitrary location after the delete.
+** But if that bit is set, then the cursor is left in a state such that
+** the next call to BtreeNext() or BtreePrev() moves it to the same row
+** as it would have been on if the call to BtreeDelete() had been omitted.
+**
+** The BTREE_AUXDELETE bit of flags indicates that is one of several deletes
+** associated with a single table entry and its indexes.  Only one of those
+** deletes is considered the "primary" delete.  The primary delete occurs
+** on a cursor that is not a BTREE_FORDELETE cursor.  All but one delete
+** operation on non-FORDELETE cursors is tagged with the AUXDELETE flag.
+** The BTREE_AUXDELETE bit is a hint that is not used by this implementation,
+** but which might be used by alternative storage engines.
+*/
+SQLITE_PRIVATE int sqlite3BtreeDelete(BtCursor *pCur, u8 flags){
+  Btree *p = pCur->pBtree;
+  BtShared *pBt = p->pBt;              
+  int rc;                              /* Return code */
+  MemPage *pPage;                      /* Page to delete cell from */
+  unsigned char *pCell;                /* Pointer to cell to delete */
+  int iCellIdx;                        /* Index of cell to delete */
+  int iCellDepth;                      /* Depth of node containing pCell */ 
+  u16 szCell;                          /* Size of the cell being deleted */
+  int bSkipnext = 0;                   /* Leaf cursor in SKIPNEXT state */
+  u8 bPreserve = flags & BTREE_SAVEPOSITION;  /* Keep cursor valid */
+
+  assert( cursorOwnsBtShared(pCur) );
+  assert( pBt->inTransaction==TRANS_WRITE );
+  assert( (pBt->btsFlags & BTS_READ_ONLY)==0 );
+  assert( pCur->curFlags & BTCF_WriteFlag );
+  assert( hasSharedCacheTableLock(p, pCur->pgnoRoot, pCur->pKeyInfo!=0, 2) );
+  assert( !hasReadConflicts(p, pCur->pgnoRoot) );
+  assert( pCur->aiIdx[pCur->iPage]<pCur->apPage[pCur->iPage]->nCell );
+  assert( pCur->eState==CURSOR_VALID );
+  assert( (flags & ~(BTREE_SAVEPOSITION | BTREE_AUXDELETE))==0 );
+
+  iCellDepth = pCur->iPage;
+  iCellIdx = pCur->aiIdx[iCellDepth];
+  pPage = pCur->apPage[iCellDepth];
+  pCell = findCell(pPage, iCellIdx);
+
+  /* If the bPreserve flag is set to true, then the cursor position must
+  ** be preserved following this delete operation. If the current delete
+  ** will cause a b-tree rebalance, then this is done by saving the cursor
+  ** key and leaving the cursor in CURSOR_REQUIRESEEK state before 
+  ** returning. 
+  **
+  ** Or, if the current delete will not cause a rebalance, then the cursor
+  ** will be left in CURSOR_SKIPNEXT state pointing to the entry immediately
+  ** before or after the deleted entry. In this case set bSkipnext to true.  */
+  if( bPreserve ){
+    if( !pPage->leaf 
+     || (pPage->nFree+cellSizePtr(pPage,pCell)+2)>(int)(pBt->usableSize*2/3)
+    ){
+      /* A b-tree rebalance will be required after deleting this entry.
+      ** Save the cursor key.  */
+      rc = saveCursorKey(pCur);
+      if( rc ) return rc;
+    }else{
+      bSkipnext = 1;
+    }
+  }
+
+  /* If the page containing the entry to delete is not a leaf page, move
+  ** the cursor to the largest entry in the tree that is smaller than
+  ** the entry being deleted. This cell will replace the cell being deleted
+  ** from the internal node. The 'previous' entry is used for this instead
+  ** of the 'next' entry, as the previous entry is always a part of the
+  ** sub-tree headed by the child page of the cell being deleted. This makes
+  ** balancing the tree following the delete operation easier.  */
+  if( !pPage->leaf ){
+    int notUsed = 0;
+    rc = sqlite3BtreePrevious(pCur, &notUsed);
+    if( rc ) return rc;
+  }
+
+  /* Save the positions of any other cursors open on this table before
+  ** making any modifications.  */
+  if( pCur->curFlags & BTCF_Multiple ){
+    rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur);
+    if( rc ) return rc;
+  }
+
+  /* If this is a delete operation to remove a row from a table b-tree,
+  ** invalidate any incrblob cursors open on the row being deleted.  */
+  if( pCur->pKeyInfo==0 ){
+    invalidateIncrblobCursors(p, pCur->info.nKey, 0);
+  }
+
+  /* Make the page containing the entry to be deleted writable. Then free any
+  ** overflow pages associated with the entry and finally remove the cell
+  ** itself from within the page.  */
+  rc = sqlite3PagerWrite(pPage->pDbPage);
+  if( rc ) return rc;
+  rc = clearCell(pPage, pCell, &szCell);
+  dropCell(pPage, iCellIdx, szCell, &rc);
+  if( rc ) return rc;
+
+  /* If the cell deleted was not located on a leaf page, then the cursor
+  ** is currently pointing to the largest entry in the sub-tree headed
+  ** by the child-page of the cell that was just deleted from an internal
+  ** node. The cell from the leaf node needs to be moved to the internal
+  ** node to replace the deleted cell.  */
+  if( !pPage->leaf ){
+    MemPage *pLeaf = pCur->apPage[pCur->iPage];
+    int nCell;
+    Pgno n = pCur->apPage[iCellDepth+1]->pgno;
+    unsigned char *pTmp;
+
+    pCell = findCell(pLeaf, pLeaf->nCell-1);
+    if( pCell<&pLeaf->aData[4] ) return SQLITE_CORRUPT_BKPT;
+    nCell = pLeaf->xCellSize(pLeaf, pCell);
+    assert( MX_CELL_SIZE(pBt) >= nCell );
+    pTmp = pBt->pTmpSpace;
+    assert( pTmp!=0 );
+    rc = sqlite3PagerWrite(pLeaf->pDbPage);
+    if( rc==SQLITE_OK ){
+      insertCell(pPage, iCellIdx, pCell-4, nCell+4, pTmp, n, &rc);
+    }
+    dropCell(pLeaf, pLeaf->nCell-1, nCell, &rc);
+    if( rc ) return rc;
+  }
+
+  /* Balance the tree. If the entry deleted was located on a leaf page,
+  ** then the cursor still points to that page. In this case the first
+  ** call to balance() repairs the tree, and the if(...) condition is
+  ** never true.
+  **
+  ** Otherwise, if the entry deleted was on an internal node page, then
+  ** pCur is pointing to the leaf page from which a cell was removed to
+  ** replace the cell deleted from the internal node. This is slightly
+  ** tricky as the leaf node may be underfull, and the internal node may
+  ** be either under or overfull. In this case run the balancing algorithm
+  ** on the leaf node first. If the balance proceeds far enough up the
+  ** tree that we can be sure that any problem in the internal node has
+  ** been corrected, so be it. Otherwise, after balancing the leaf node,
+  ** walk the cursor up the tree to the internal node and balance it as 
+  ** well.  */
+  rc = balance(pCur);
+  if( rc==SQLITE_OK && pCur->iPage>iCellDepth ){
+    while( pCur->iPage>iCellDepth ){
+      releasePage(pCur->apPage[pCur->iPage--]);
+    }
+    rc = balance(pCur);
+  }
+
+  if( rc==SQLITE_OK ){
+    if( bSkipnext ){
+      assert( bPreserve && (pCur->iPage==iCellDepth || CORRUPT_DB) );
+      assert( pPage==pCur->apPage[pCur->iPage] || CORRUPT_DB );
+      assert( (pPage->nCell>0 || CORRUPT_DB) && iCellIdx<=pPage->nCell );
+      pCur->eState = CURSOR_SKIPNEXT;
+      if( iCellIdx>=pPage->nCell ){
+        pCur->skipNext = -1;
+        pCur->aiIdx[iCellDepth] = pPage->nCell-1;
+      }else{
+        pCur->skipNext = 1;
+      }
+    }else{
+      rc = moveToRoot(pCur);
+      if( bPreserve ){
+        pCur->eState = CURSOR_REQUIRESEEK;
+      }
+    }
+  }
+  return rc;
+}
+
+/*
+** Create a new BTree table.  Write into *piTable the page
+** number for the root page of the new table.
+**
+** The type of type is determined by the flags parameter.  Only the
+** following values of flags are currently in use.  Other values for
+** flags might not work:
+**
+**     BTREE_INTKEY|BTREE_LEAFDATA     Used for SQL tables with rowid keys
+**     BTREE_ZERODATA                  Used for SQL indices
+*/
+static int btreeCreateTable(Btree *p, int *piTable, int createTabFlags){
+  BtShared *pBt = p->pBt;
+  MemPage *pRoot;
+  Pgno pgnoRoot;
+  int rc;
+  int ptfFlags;          /* Page-type flage for the root page of new table */
+
+  assert( sqlite3BtreeHoldsMutex(p) );
+  assert( pBt->inTransaction==TRANS_WRITE );
+  assert( (pBt->btsFlags & BTS_READ_ONLY)==0 );
+
+#ifdef SQLITE_OMIT_AUTOVACUUM
+  rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0);
+  if( rc ){
+    return rc;
+  }
+#else
+  if( pBt->autoVacuum ){
+    Pgno pgnoMove;      /* Move a page here to make room for the root-page */
+    MemPage *pPageMove; /* The page to move to. */
+
+    /* Creating a new table may probably require moving an existing database
+    ** to make room for the new tables root page. In case this page turns
+    ** out to be an overflow page, delete all overflow page-map caches
+    ** held by open cursors.
+    */
+    invalidateAllOverflowCache(pBt);
+
+    /* Read the value of meta[3] from the database to determine where the
+    ** root page of the new table should go. meta[3] is the largest root-page
+    ** created so far, so the new root-page is (meta[3]+1).
+    */
+    sqlite3BtreeGetMeta(p, BTREE_LARGEST_ROOT_PAGE, &pgnoRoot);
+    pgnoRoot++;
+
+    /* The new root-page may not be allocated on a pointer-map page, or the
+    ** PENDING_BYTE page.
+    */
+    while( pgnoRoot==PTRMAP_PAGENO(pBt, pgnoRoot) ||
+        pgnoRoot==PENDING_BYTE_PAGE(pBt) ){
+      pgnoRoot++;
+    }
+    assert( pgnoRoot>=3 || CORRUPT_DB );
+    testcase( pgnoRoot<3 );
+
+    /* Allocate a page. The page that currently resides at pgnoRoot will
+    ** be moved to the allocated page (unless the allocated page happens
+    ** to reside at pgnoRoot).
+    */
+    rc = allocateBtreePage(pBt, &pPageMove, &pgnoMove, pgnoRoot, BTALLOC_EXACT);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+
+    if( pgnoMove!=pgnoRoot ){
+      /* pgnoRoot is the page that will be used for the root-page of
+      ** the new table (assuming an error did not occur). But we were
+      ** allocated pgnoMove. If required (i.e. if it was not allocated
+      ** by extending the file), the current page at position pgnoMove
+      ** is already journaled.
+      */
+      u8 eType = 0;
+      Pgno iPtrPage = 0;
+
+      /* Save the positions of any open cursors. This is required in
+      ** case they are holding a reference to an xFetch reference
+      ** corresponding to page pgnoRoot.  */
+      rc = saveAllCursors(pBt, 0, 0);
+      releasePage(pPageMove);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+
+      /* Move the page currently at pgnoRoot to pgnoMove. */
+      rc = btreeGetPage(pBt, pgnoRoot, &pRoot, 0);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+      rc = ptrmapGet(pBt, pgnoRoot, &eType, &iPtrPage);
+      if( eType==PTRMAP_ROOTPAGE || eType==PTRMAP_FREEPAGE ){
+        rc = SQLITE_CORRUPT_BKPT;
+      }
+      if( rc!=SQLITE_OK ){
+        releasePage(pRoot);
+        return rc;
+      }
+      assert( eType!=PTRMAP_ROOTPAGE );
+      assert( eType!=PTRMAP_FREEPAGE );
+      rc = relocatePage(pBt, pRoot, eType, iPtrPage, pgnoMove, 0);
+      releasePage(pRoot);
+
+      /* Obtain the page at pgnoRoot */
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+      rc = btreeGetPage(pBt, pgnoRoot, &pRoot, 0);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+      rc = sqlite3PagerWrite(pRoot->pDbPage);
+      if( rc!=SQLITE_OK ){
+        releasePage(pRoot);
+        return rc;
+      }
+    }else{
+      pRoot = pPageMove;
+    } 
+
+    /* Update the pointer-map and meta-data with the new root-page number. */
+    ptrmapPut(pBt, pgnoRoot, PTRMAP_ROOTPAGE, 0, &rc);
+    if( rc ){
+      releasePage(pRoot);
+      return rc;
+    }
+
+    /* When the new root page was allocated, page 1 was made writable in
+    ** order either to increase the database filesize, or to decrement the
+    ** freelist count.  Hence, the sqlite3BtreeUpdateMeta() call cannot fail.
+    */
+    assert( sqlite3PagerIswriteable(pBt->pPage1->pDbPage) );
+    rc = sqlite3BtreeUpdateMeta(p, 4, pgnoRoot);
+    if( NEVER(rc) ){
+      releasePage(pRoot);
+      return rc;
+    }
+
+  }else{
+    rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0);
+    if( rc ) return rc;
+  }
+#endif
+  assert( sqlite3PagerIswriteable(pRoot->pDbPage) );
+  if( createTabFlags & BTREE_INTKEY ){
+    ptfFlags = PTF_INTKEY | PTF_LEAFDATA | PTF_LEAF;
+  }else{
+    ptfFlags = PTF_ZERODATA | PTF_LEAF;
+  }
+  zeroPage(pRoot, ptfFlags);
+  sqlite3PagerUnref(pRoot->pDbPage);
+  assert( (pBt->openFlags & BTREE_SINGLE)==0 || pgnoRoot==2 );
+  *piTable = (int)pgnoRoot;
+  return SQLITE_OK;
+}
+SQLITE_PRIVATE int sqlite3BtreeCreateTable(Btree *p, int *piTable, int flags){
+  int rc;
+  sqlite3BtreeEnter(p);
+  rc = btreeCreateTable(p, piTable, flags);
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+/*
+** Erase the given database page and all its children.  Return
+** the page to the freelist.
+*/
+static int clearDatabasePage(
+  BtShared *pBt,           /* The BTree that contains the table */
+  Pgno pgno,               /* Page number to clear */
+  int freePageFlag,        /* Deallocate page if true */
+  int *pnChange            /* Add number of Cells freed to this counter */
+){
+  MemPage *pPage;
+  int rc;
+  unsigned char *pCell;
+  int i;
+  int hdr;
+  u16 szCell;
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  if( pgno>btreePagecount(pBt) ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+  rc = getAndInitPage(pBt, pgno, &pPage, 0, 0);
+  if( rc ) return rc;
+  if( pPage->bBusy ){
+    rc = SQLITE_CORRUPT_BKPT;
+    goto cleardatabasepage_out;
+  }
+  pPage->bBusy = 1;
+  hdr = pPage->hdrOffset;
+  for(i=0; i<pPage->nCell; i++){
+    pCell = findCell(pPage, i);
+    if( !pPage->leaf ){
+      rc = clearDatabasePage(pBt, get4byte(pCell), 1, pnChange);
+      if( rc ) goto cleardatabasepage_out;
+    }
+    rc = clearCell(pPage, pCell, &szCell);
+    if( rc ) goto cleardatabasepage_out;
+  }
+  if( !pPage->leaf ){
+    rc = clearDatabasePage(pBt, get4byte(&pPage->aData[hdr+8]), 1, pnChange);
+    if( rc ) goto cleardatabasepage_out;
+  }else if( pnChange ){
+    assert( pPage->intKey || CORRUPT_DB );
+    testcase( !pPage->intKey );
+    *pnChange += pPage->nCell;
+  }
+  if( freePageFlag ){
+    freePage(pPage, &rc);
+  }else if( (rc = sqlite3PagerWrite(pPage->pDbPage))==0 ){
+    zeroPage(pPage, pPage->aData[hdr] | PTF_LEAF);
+  }
+
+cleardatabasepage_out:
+  pPage->bBusy = 0;
+  releasePage(pPage);
+  return rc;
+}
+
+/*
+** Delete all information from a single table in the database.  iTable is
+** the page number of the root of the table.  After this routine returns,
+** the root page is empty, but still exists.
+**
+** This routine will fail with SQLITE_LOCKED if there are any open
+** read cursors on the table.  Open write cursors are moved to the
+** root of the table.
+**
+** If pnChange is not NULL, then table iTable must be an intkey table. The
+** integer value pointed to by pnChange is incremented by the number of
+** entries in the table.
+*/
+SQLITE_PRIVATE int sqlite3BtreeClearTable(Btree *p, int iTable, int *pnChange){
+  int rc;
+  BtShared *pBt = p->pBt;
+  sqlite3BtreeEnter(p);
+  assert( p->inTrans==TRANS_WRITE );
+
+  rc = saveAllCursors(pBt, (Pgno)iTable, 0);
+
+  if( SQLITE_OK==rc ){
+    /* Invalidate all incrblob cursors open on table iTable (assuming iTable
+    ** is the root of a table b-tree - if it is not, the following call is
+    ** a no-op).  */
+    invalidateIncrblobCursors(p, 0, 1);
+    rc = clearDatabasePage(pBt, (Pgno)iTable, 0, pnChange);
+  }
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+/*
+** Delete all information from the single table that pCur is open on.
+**
+** This routine only work for pCur on an ephemeral table.
+*/
+SQLITE_PRIVATE int sqlite3BtreeClearTableOfCursor(BtCursor *pCur){
+  return sqlite3BtreeClearTable(pCur->pBtree, pCur->pgnoRoot, 0);
+}
+
+/*
+** Erase all information in a table and add the root of the table to
+** the freelist.  Except, the root of the principle table (the one on
+** page 1) is never added to the freelist.
+**
+** This routine will fail with SQLITE_LOCKED if there are any open
+** cursors on the table.
+**
+** If AUTOVACUUM is enabled and the page at iTable is not the last
+** root page in the database file, then the last root page 
+** in the database file is moved into the slot formerly occupied by
+** iTable and that last slot formerly occupied by the last root page
+** is added to the freelist instead of iTable.  In this say, all
+** root pages are kept at the beginning of the database file, which
+** is necessary for AUTOVACUUM to work right.  *piMoved is set to the 
+** page number that used to be the last root page in the file before
+** the move.  If no page gets moved, *piMoved is set to 0.
+** The last root page is recorded in meta[3] and the value of
+** meta[3] is updated by this procedure.
+*/
+static int btreeDropTable(Btree *p, Pgno iTable, int *piMoved){
+  int rc;
+  MemPage *pPage = 0;
+  BtShared *pBt = p->pBt;
+
+  assert( sqlite3BtreeHoldsMutex(p) );
+  assert( p->inTrans==TRANS_WRITE );
+
+  /* It is illegal to drop a table if any cursors are open on the
+  ** database. This is because in auto-vacuum mode the backend may
+  ** need to move another root-page to fill a gap left by the deleted
+  ** root page. If an open cursor was using this page a problem would 
+  ** occur.
+  **
+  ** This error is caught long before control reaches this point.
+  */
+  if( NEVER(pBt->pCursor) ){
+    sqlite3ConnectionBlocked(p->db, pBt->pCursor->pBtree->db);
+    return SQLITE_LOCKED_SHAREDCACHE;
+  }
+
+  /*
+  ** It is illegal to drop the sqlite_master table on page 1.  But again,
+  ** this error is caught long before reaching this point.
+  */
+  if( NEVER(iTable<2) ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+
+  rc = btreeGetPage(pBt, (Pgno)iTable, &pPage, 0);
+  if( rc ) return rc;
+  rc = sqlite3BtreeClearTable(p, iTable, 0);
+  if( rc ){
+    releasePage(pPage);
+    return rc;
+  }
+
+  *piMoved = 0;
+
+#ifdef SQLITE_OMIT_AUTOVACUUM
+  freePage(pPage, &rc);
+  releasePage(pPage);
+#else
+  if( pBt->autoVacuum ){
+    Pgno maxRootPgno;
+    sqlite3BtreeGetMeta(p, BTREE_LARGEST_ROOT_PAGE, &maxRootPgno);
+
+    if( iTable==maxRootPgno ){
+      /* If the table being dropped is the table with the largest root-page
+      ** number in the database, put the root page on the free list. 
+      */
+      freePage(pPage, &rc);
+      releasePage(pPage);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+    }else{
+      /* The table being dropped does not have the largest root-page
+      ** number in the database. So move the page that does into the 
+      ** gap left by the deleted root-page.
+      */
+      MemPage *pMove;
+      releasePage(pPage);
+      rc = btreeGetPage(pBt, maxRootPgno, &pMove, 0);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+      rc = relocatePage(pBt, pMove, PTRMAP_ROOTPAGE, 0, iTable, 0);
+      releasePage(pMove);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+      pMove = 0;
+      rc = btreeGetPage(pBt, maxRootPgno, &pMove, 0);
+      freePage(pMove, &rc);
+      releasePage(pMove);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+      *piMoved = maxRootPgno;
+    }
+
+    /* Set the new 'max-root-page' value in the database header. This
+    ** is the old value less one, less one more if that happens to
+    ** be a root-page number, less one again if that is the
+    ** PENDING_BYTE_PAGE.
+    */
+    maxRootPgno--;
+    while( maxRootPgno==PENDING_BYTE_PAGE(pBt)
+           || PTRMAP_ISPAGE(pBt, maxRootPgno) ){
+      maxRootPgno--;
+    }
+    assert( maxRootPgno!=PENDING_BYTE_PAGE(pBt) );
+
+    rc = sqlite3BtreeUpdateMeta(p, 4, maxRootPgno);
+  }else{
+    freePage(pPage, &rc);
+    releasePage(pPage);
+  }
+#endif
+  return rc;  
+}
+SQLITE_PRIVATE int sqlite3BtreeDropTable(Btree *p, int iTable, int *piMoved){
+  int rc;
+  sqlite3BtreeEnter(p);
+  rc = btreeDropTable(p, iTable, piMoved);
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+
+/*
+** This function may only be called if the b-tree connection already
+** has a read or write transaction open on the database.
+**
+** Read the meta-information out of a database file.  Meta[0]
+** is the number of free pages currently in the database.  Meta[1]
+** through meta[15] are available for use by higher layers.  Meta[0]
+** is read-only, the others are read/write.
+** 
+** The schema layer numbers meta values differently.  At the schema
+** layer (and the SetCookie and ReadCookie opcodes) the number of
+** free pages is not visible.  So Cookie[0] is the same as Meta[1].
+**
+** This routine treats Meta[BTREE_DATA_VERSION] as a special case.  Instead
+** of reading the value out of the header, it instead loads the "DataVersion"
+** from the pager.  The BTREE_DATA_VERSION value is not actually stored in the
+** database file.  It is a number computed by the pager.  But its access
+** pattern is the same as header meta values, and so it is convenient to
+** read it from this routine.
+*/
+SQLITE_PRIVATE void sqlite3BtreeGetMeta(Btree *p, int idx, u32 *pMeta){
+  BtShared *pBt = p->pBt;
+
+  sqlite3BtreeEnter(p);
+  assert( p->inTrans>TRANS_NONE );
+  assert( SQLITE_OK==querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK) );
+  assert( pBt->pPage1 );
+  assert( idx>=0 && idx<=15 );
+
+  if( idx==BTREE_DATA_VERSION ){
+    *pMeta = sqlite3PagerDataVersion(pBt->pPager) + p->iDataVersion;
+  }else{
+    *pMeta = get4byte(&pBt->pPage1->aData[36 + idx*4]);
+  }
+
+  /* If auto-vacuum is disabled in this build and this is an auto-vacuum
+  ** database, mark the database as read-only.  */
+#ifdef SQLITE_OMIT_AUTOVACUUM
+  if( idx==BTREE_LARGEST_ROOT_PAGE && *pMeta>0 ){
+    pBt->btsFlags |= BTS_READ_ONLY;
+  }
+#endif
+
+  sqlite3BtreeLeave(p);
+}
+
+/*
+** Write meta-information back into the database.  Meta[0] is
+** read-only and may not be written.
+*/
+SQLITE_PRIVATE int sqlite3BtreeUpdateMeta(Btree *p, int idx, u32 iMeta){
+  BtShared *pBt = p->pBt;
+  unsigned char *pP1;
+  int rc;
+  assert( idx>=1 && idx<=15 );
+  sqlite3BtreeEnter(p);
+  assert( p->inTrans==TRANS_WRITE );
+  assert( pBt->pPage1!=0 );
+  pP1 = pBt->pPage1->aData;
+  rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
+  if( rc==SQLITE_OK ){
+    put4byte(&pP1[36 + idx*4], iMeta);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    if( idx==BTREE_INCR_VACUUM ){
+      assert( pBt->autoVacuum || iMeta==0 );
+      assert( iMeta==0 || iMeta==1 );
+      pBt->incrVacuum = (u8)iMeta;
+    }
+#endif
+  }
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+#ifndef SQLITE_OMIT_BTREECOUNT
+/*
+** The first argument, pCur, is a cursor opened on some b-tree. Count the
+** number of entries in the b-tree and write the result to *pnEntry.
+**
+** SQLITE_OK is returned if the operation is successfully executed. 
+** Otherwise, if an error is encountered (i.e. an IO error or database
+** corruption) an SQLite error code is returned.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCount(BtCursor *pCur, i64 *pnEntry){
+  i64 nEntry = 0;                      /* Value to return in *pnEntry */
+  int rc;                              /* Return code */
+
+  if( pCur->pgnoRoot==0 ){
+    *pnEntry = 0;
+    return SQLITE_OK;
+  }
+  rc = moveToRoot(pCur);
+
+  /* Unless an error occurs, the following loop runs one iteration for each
+  ** page in the B-Tree structure (not including overflow pages). 
+  */
+  while( rc==SQLITE_OK ){
+    int iIdx;                          /* Index of child node in parent */
+    MemPage *pPage;                    /* Current page of the b-tree */
+
+    /* If this is a leaf page or the tree is not an int-key tree, then 
+    ** this page contains countable entries. Increment the entry counter
+    ** accordingly.
+    */
+    pPage = pCur->apPage[pCur->iPage];
+    if( pPage->leaf || !pPage->intKey ){
+      nEntry += pPage->nCell;
+    }
+
+    /* pPage is a leaf node. This loop navigates the cursor so that it 
+    ** points to the first interior cell that it points to the parent of
+    ** the next page in the tree that has not yet been visited. The
+    ** pCur->aiIdx[pCur->iPage] value is set to the index of the parent cell
+    ** of the page, or to the number of cells in the page if the next page
+    ** to visit is the right-child of its parent.
+    **
+    ** If all pages in the tree have been visited, return SQLITE_OK to the
+    ** caller.
+    */
+    if( pPage->leaf ){
+      do {
+        if( pCur->iPage==0 ){
+          /* All pages of the b-tree have been visited. Return successfully. */
+          *pnEntry = nEntry;
+          return moveToRoot(pCur);
+        }
+        moveToParent(pCur);
+      }while ( pCur->aiIdx[pCur->iPage]>=pCur->apPage[pCur->iPage]->nCell );
+
+      pCur->aiIdx[pCur->iPage]++;
+      pPage = pCur->apPage[pCur->iPage];
+    }
+
+    /* Descend to the child node of the cell that the cursor currently 
+    ** points at. This is the right-child if (iIdx==pPage->nCell).
+    */
+    iIdx = pCur->aiIdx[pCur->iPage];
+    if( iIdx==pPage->nCell ){
+      rc = moveToChild(pCur, get4byte(&pPage->aData[pPage->hdrOffset+8]));
+    }else{
+      rc = moveToChild(pCur, get4byte(findCell(pPage, iIdx)));
+    }
+  }
+
+  /* An error has occurred. Return an error code. */
+  return rc;
+}
+#endif
+
+/*
+** Return the pager associated with a BTree.  This routine is used for
+** testing and debugging only.
+*/
+SQLITE_PRIVATE Pager *sqlite3BtreePager(Btree *p){
+  return p->pBt->pPager;
+}
+
+#ifndef SQLITE_OMIT_INTEGRITY_CHECK
+/*
+** Append a message to the error message string.
+*/
+static void checkAppendMsg(
+  IntegrityCk *pCheck,
+  const char *zFormat,
+  ...
+){
+  va_list ap;
+  if( !pCheck->mxErr ) return;
+  pCheck->mxErr--;
+  pCheck->nErr++;
+  va_start(ap, zFormat);
+  if( pCheck->errMsg.nChar ){
+    sqlite3StrAccumAppend(&pCheck->errMsg, "\n", 1);
+  }
+  if( pCheck->zPfx ){
+    sqlite3XPrintf(&pCheck->errMsg, pCheck->zPfx, pCheck->v1, pCheck->v2);
+  }
+  sqlite3VXPrintf(&pCheck->errMsg, zFormat, ap);
+  va_end(ap);
+  if( pCheck->errMsg.accError==STRACCUM_NOMEM ){
+    pCheck->mallocFailed = 1;
+  }
+}
+#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
+
+#ifndef SQLITE_OMIT_INTEGRITY_CHECK
+
+/*
+** Return non-zero if the bit in the IntegrityCk.aPgRef[] array that
+** corresponds to page iPg is already set.
+*/
+static int getPageReferenced(IntegrityCk *pCheck, Pgno iPg){
+  assert( iPg<=pCheck->nPage && sizeof(pCheck->aPgRef[0])==1 );
+  return (pCheck->aPgRef[iPg/8] & (1 << (iPg & 0x07)));
+}
+
+/*
+** Set the bit in the IntegrityCk.aPgRef[] array that corresponds to page iPg.
+*/
+static void setPageReferenced(IntegrityCk *pCheck, Pgno iPg){
+  assert( iPg<=pCheck->nPage && sizeof(pCheck->aPgRef[0])==1 );
+  pCheck->aPgRef[iPg/8] |= (1 << (iPg & 0x07));
+}
+
+
+/*
+** Add 1 to the reference count for page iPage.  If this is the second
+** reference to the page, add an error message to pCheck->zErrMsg.
+** Return 1 if there are 2 or more references to the page and 0 if
+** if this is the first reference to the page.
+**
+** Also check that the page number is in bounds.
+*/
+static int checkRef(IntegrityCk *pCheck, Pgno iPage){
+  if( iPage==0 ) return 1;
+  if( iPage>pCheck->nPage ){
+    checkAppendMsg(pCheck, "invalid page number %d", iPage);
+    return 1;
+  }
+  if( getPageReferenced(pCheck, iPage) ){
+    checkAppendMsg(pCheck, "2nd reference to page %d", iPage);
+    return 1;
+  }
+  setPageReferenced(pCheck, iPage);
+  return 0;
+}
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+/*
+** Check that the entry in the pointer-map for page iChild maps to 
+** page iParent, pointer type ptrType. If not, append an error message
+** to pCheck.
+*/
+static void checkPtrmap(
+  IntegrityCk *pCheck,   /* Integrity check context */
+  Pgno iChild,           /* Child page number */
+  u8 eType,              /* Expected pointer map type */
+  Pgno iParent           /* Expected pointer map parent page number */
+){
+  int rc;
+  u8 ePtrmapType;
+  Pgno iPtrmapParent;
+
+  rc = ptrmapGet(pCheck->pBt, iChild, &ePtrmapType, &iPtrmapParent);
+  if( rc!=SQLITE_OK ){
+    if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ) pCheck->mallocFailed = 1;
+    checkAppendMsg(pCheck, "Failed to read ptrmap key=%d", iChild);
+    return;
+  }
+
+  if( ePtrmapType!=eType || iPtrmapParent!=iParent ){
+    checkAppendMsg(pCheck,
+      "Bad ptr map entry key=%d expected=(%d,%d) got=(%d,%d)", 
+      iChild, eType, iParent, ePtrmapType, iPtrmapParent);
+  }
+}
+#endif
+
+/*
+** Check the integrity of the freelist or of an overflow page list.
+** Verify that the number of pages on the list is N.
+*/
+static void checkList(
+  IntegrityCk *pCheck,  /* Integrity checking context */
+  int isFreeList,       /* True for a freelist.  False for overflow page list */
+  int iPage,            /* Page number for first page in the list */
+  int N                 /* Expected number of pages in the list */
+){
+  int i;
+  int expected = N;
+  int iFirst = iPage;
+  while( N-- > 0 && pCheck->mxErr ){
+    DbPage *pOvflPage;
+    unsigned char *pOvflData;
+    if( iPage<1 ){
+      checkAppendMsg(pCheck,
+         "%d of %d pages missing from overflow list starting at %d",
+          N+1, expected, iFirst);
+      break;
+    }
+    if( checkRef(pCheck, iPage) ) break;
+    if( sqlite3PagerGet(pCheck->pPager, (Pgno)iPage, &pOvflPage, 0) ){
+      checkAppendMsg(pCheck, "failed to get page %d", iPage);
+      break;
+    }
+    pOvflData = (unsigned char *)sqlite3PagerGetData(pOvflPage);
+    if( isFreeList ){
+      int n = get4byte(&pOvflData[4]);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+      if( pCheck->pBt->autoVacuum ){
+        checkPtrmap(pCheck, iPage, PTRMAP_FREEPAGE, 0);
+      }
+#endif
+      if( n>(int)pCheck->pBt->usableSize/4-2 ){
+        checkAppendMsg(pCheck,
+           "freelist leaf count too big on page %d", iPage);
+        N--;
+      }else{
+        for(i=0; i<n; i++){
+          Pgno iFreePage = get4byte(&pOvflData[8+i*4]);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+          if( pCheck->pBt->autoVacuum ){
+            checkPtrmap(pCheck, iFreePage, PTRMAP_FREEPAGE, 0);
+          }
+#endif
+          checkRef(pCheck, iFreePage);
+        }
+        N -= n;
+      }
+    }
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    else{
+      /* If this database supports auto-vacuum and iPage is not the last
+      ** page in this overflow list, check that the pointer-map entry for
+      ** the following page matches iPage.
+      */
+      if( pCheck->pBt->autoVacuum && N>0 ){
+        i = get4byte(pOvflData);
+        checkPtrmap(pCheck, i, PTRMAP_OVERFLOW2, iPage);
+      }
+    }
+#endif
+    iPage = get4byte(pOvflData);
+    sqlite3PagerUnref(pOvflPage);
+
+    if( isFreeList && N<(iPage!=0) ){
+      checkAppendMsg(pCheck, "free-page count in header is too small");
+    }
+  }
+}
+#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
+
+/*
+** An implementation of a min-heap.
+**
+** aHeap[0] is the number of elements on the heap.  aHeap[1] is the
+** root element.  The daughter nodes of aHeap[N] are aHeap[N*2]
+** and aHeap[N*2+1].
+**
+** The heap property is this:  Every node is less than or equal to both
+** of its daughter nodes.  A consequence of the heap property is that the
+** root node aHeap[1] is always the minimum value currently in the heap.
+**
+** The btreeHeapInsert() routine inserts an unsigned 32-bit number onto
+** the heap, preserving the heap property.  The btreeHeapPull() routine
+** removes the root element from the heap (the minimum value in the heap)
+** and then moves other nodes around as necessary to preserve the heap
+** property.
+**
+** This heap is used for cell overlap and coverage testing.  Each u32
+** entry represents the span of a cell or freeblock on a btree page.  
+** The upper 16 bits are the index of the first byte of a range and the
+** lower 16 bits are the index of the last byte of that range.
+*/
+static void btreeHeapInsert(u32 *aHeap, u32 x){
+  u32 j, i = ++aHeap[0];
+  aHeap[i] = x;
+  while( (j = i/2)>0 && aHeap[j]>aHeap[i] ){
+    x = aHeap[j];
+    aHeap[j] = aHeap[i];
+    aHeap[i] = x;
+    i = j;
+  }
+}
+static int btreeHeapPull(u32 *aHeap, u32 *pOut){
+  u32 j, i, x;
+  if( (x = aHeap[0])==0 ) return 0;
+  *pOut = aHeap[1];
+  aHeap[1] = aHeap[x];
+  aHeap[x] = 0xffffffff;
+  aHeap[0]--;
+  i = 1;
+  while( (j = i*2)<=aHeap[0] ){
+    if( aHeap[j]>aHeap[j+1] ) j++;
+    if( aHeap[i]<aHeap[j] ) break;
+    x = aHeap[i];
+    aHeap[i] = aHeap[j];
+    aHeap[j] = x;
+    i = j;
+  }
+  return 1;  
+}
+
+#ifndef SQLITE_OMIT_INTEGRITY_CHECK
+/*
+** Do various sanity checks on a single page of a tree.  Return
+** the tree depth.  Root pages return 0.  Parents of root pages
+** return 1, and so forth.
+** 
+** These checks are done:
+**
+**      1.  Make sure that cells and freeblocks do not overlap
+**          but combine to completely cover the page.
+**      2.  Make sure integer cell keys are in order.
+**      3.  Check the integrity of overflow pages.
+**      4.  Recursively call checkTreePage on all children.
+**      5.  Verify that the depth of all children is the same.
+*/
+static int checkTreePage(
+  IntegrityCk *pCheck,  /* Context for the sanity check */
+  int iPage,            /* Page number of the page to check */
+  i64 *piMinKey,        /* Write minimum integer primary key here */
+  i64 maxKey            /* Error if integer primary key greater than this */
+){
+  MemPage *pPage = 0;      /* The page being analyzed */
+  int i;                   /* Loop counter */
+  int rc;                  /* Result code from subroutine call */
+  int depth = -1, d2;      /* Depth of a subtree */
+  int pgno;                /* Page number */
+  int nFrag;               /* Number of fragmented bytes on the page */
+  int hdr;                 /* Offset to the page header */
+  int cellStart;           /* Offset to the start of the cell pointer array */
+  int nCell;               /* Number of cells */
+  int doCoverageCheck = 1; /* True if cell coverage checking should be done */
+  int keyCanBeEqual = 1;   /* True if IPK can be equal to maxKey
+                           ** False if IPK must be strictly less than maxKey */
+  u8 *data;                /* Page content */
+  u8 *pCell;               /* Cell content */
+  u8 *pCellIdx;            /* Next element of the cell pointer array */
+  BtShared *pBt;           /* The BtShared object that owns pPage */
+  u32 pc;                  /* Address of a cell */
+  u32 usableSize;          /* Usable size of the page */
+  u32 contentOffset;       /* Offset to the start of the cell content area */
+  u32 *heap = 0;           /* Min-heap used for checking cell coverage */
+  u32 x, prev = 0;         /* Next and previous entry on the min-heap */
+  const char *saved_zPfx = pCheck->zPfx;
+  int saved_v1 = pCheck->v1;
+  int saved_v2 = pCheck->v2;
+  u8 savedIsInit = 0;
+
+  /* Check that the page exists
+  */
+  pBt = pCheck->pBt;
+  usableSize = pBt->usableSize;
+  if( iPage==0 ) return 0;
+  if( checkRef(pCheck, iPage) ) return 0;
+  pCheck->zPfx = "Page %d: ";
+  pCheck->v1 = iPage;
+  if( (rc = btreeGetPage(pBt, (Pgno)iPage, &pPage, 0))!=0 ){
+    checkAppendMsg(pCheck,
+       "unable to get the page. error code=%d", rc);
+    goto end_of_check;
+  }
+
+  /* Clear MemPage.isInit to make sure the corruption detection code in
+  ** btreeInitPage() is executed.  */
+  savedIsInit = pPage->isInit;
+  pPage->isInit = 0;
+  if( (rc = btreeInitPage(pPage))!=0 ){
+    assert( rc==SQLITE_CORRUPT );  /* The only possible error from InitPage */
+    checkAppendMsg(pCheck,
+                   "btreeInitPage() returns error code %d", rc);
+    goto end_of_check;
+  }
+  data = pPage->aData;
+  hdr = pPage->hdrOffset;
+
+  /* Set up for cell analysis */
+  pCheck->zPfx = "On tree page %d cell %d: ";
+  contentOffset = get2byteNotZero(&data[hdr+5]);
+  assert( contentOffset<=usableSize );  /* Enforced by btreeInitPage() */
+
+  /* EVIDENCE-OF: R-37002-32774 The two-byte integer at offset 3 gives the
+  ** number of cells on the page. */
+  nCell = get2byte(&data[hdr+3]);
+  assert( pPage->nCell==nCell );
+
+  /* EVIDENCE-OF: R-23882-45353 The cell pointer array of a b-tree page
+  ** immediately follows the b-tree page header. */
+  cellStart = hdr + 12 - 4*pPage->leaf;
+  assert( pPage->aCellIdx==&data[cellStart] );
+  pCellIdx = &data[cellStart + 2*(nCell-1)];
+
+  if( !pPage->leaf ){
+    /* Analyze the right-child page of internal pages */
+    pgno = get4byte(&data[hdr+8]);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    if( pBt->autoVacuum ){
+      pCheck->zPfx = "On page %d at right child: ";
+      checkPtrmap(pCheck, pgno, PTRMAP_BTREE, iPage);
+    }
+#endif
+    depth = checkTreePage(pCheck, pgno, &maxKey, maxKey);
+    keyCanBeEqual = 0;
+  }else{
+    /* For leaf pages, the coverage check will occur in the same loop
+    ** as the other cell checks, so initialize the heap.  */
+    heap = pCheck->heap;
+    heap[0] = 0;
+  }
+
+  /* EVIDENCE-OF: R-02776-14802 The cell pointer array consists of K 2-byte
+  ** integer offsets to the cell contents. */
+  for(i=nCell-1; i>=0 && pCheck->mxErr; i--){
+    CellInfo info;
+
+    /* Check cell size */
+    pCheck->v2 = i;
+    assert( pCellIdx==&data[cellStart + i*2] );
+    pc = get2byteAligned(pCellIdx);
+    pCellIdx -= 2;
+    if( pc<contentOffset || pc>usableSize-4 ){
+      checkAppendMsg(pCheck, "Offset %d out of range %d..%d",
+                             pc, contentOffset, usableSize-4);
+      doCoverageCheck = 0;
+      continue;
+    }
+    pCell = &data[pc];
+    pPage->xParseCell(pPage, pCell, &info);
+    if( pc+info.nSize>usableSize ){
+      checkAppendMsg(pCheck, "Extends off end of page");
+      doCoverageCheck = 0;
+      continue;
+    }
+
+    /* Check for integer primary key out of range */
+    if( pPage->intKey ){
+      if( keyCanBeEqual ? (info.nKey > maxKey) : (info.nKey >= maxKey) ){
+        checkAppendMsg(pCheck, "Rowid %lld out of order", info.nKey);
+      }
+      maxKey = info.nKey;
+    }
+
+    /* Check the content overflow list */
+    if( info.nPayload>info.nLocal ){
+      int nPage;       /* Number of pages on the overflow chain */
+      Pgno pgnoOvfl;   /* First page of the overflow chain */
+      assert( pc + info.nSize - 4 <= usableSize );
+      nPage = (info.nPayload - info.nLocal + usableSize - 5)/(usableSize - 4);
+      pgnoOvfl = get4byte(&pCell[info.nSize - 4]);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+      if( pBt->autoVacuum ){
+        checkPtrmap(pCheck, pgnoOvfl, PTRMAP_OVERFLOW1, iPage);
+      }
+#endif
+      checkList(pCheck, 0, pgnoOvfl, nPage);
+    }
+
+    if( !pPage->leaf ){
+      /* Check sanity of left child page for internal pages */
+      pgno = get4byte(pCell);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+      if( pBt->autoVacuum ){
+        checkPtrmap(pCheck, pgno, PTRMAP_BTREE, iPage);
+      }
+#endif
+      d2 = checkTreePage(pCheck, pgno, &maxKey, maxKey);
+      keyCanBeEqual = 0;
+      if( d2!=depth ){
+        checkAppendMsg(pCheck, "Child page depth differs");
+        depth = d2;
+      }
+    }else{
+      /* Populate the coverage-checking heap for leaf pages */
+      btreeHeapInsert(heap, (pc<<16)|(pc+info.nSize-1));
+    }
+  }
+  *piMinKey = maxKey;
+
+  /* Check for complete coverage of the page
+  */
+  pCheck->zPfx = 0;
+  if( doCoverageCheck && pCheck->mxErr>0 ){
+    /* For leaf pages, the min-heap has already been initialized and the
+    ** cells have already been inserted.  But for internal pages, that has
+    ** not yet been done, so do it now */
+    if( !pPage->leaf ){
+      heap = pCheck->heap;
+      heap[0] = 0;
+      for(i=nCell-1; i>=0; i--){
+        u32 size;
+        pc = get2byteAligned(&data[cellStart+i*2]);
+        size = pPage->xCellSize(pPage, &data[pc]);
+        btreeHeapInsert(heap, (pc<<16)|(pc+size-1));
+      }
+    }
+    /* Add the freeblocks to the min-heap
+    **
+    ** EVIDENCE-OF: R-20690-50594 The second field of the b-tree page header
+    ** is the offset of the first freeblock, or zero if there are no
+    ** freeblocks on the page. 
+    */
+    i = get2byte(&data[hdr+1]);
+    while( i>0 ){
+      int size, j;
+      assert( (u32)i<=usableSize-4 );     /* Enforced by btreeInitPage() */
+      size = get2byte(&data[i+2]);
+      assert( (u32)(i+size)<=usableSize );  /* Enforced by btreeInitPage() */
+      btreeHeapInsert(heap, (((u32)i)<<16)|(i+size-1));
+      /* EVIDENCE-OF: R-58208-19414 The first 2 bytes of a freeblock are a
+      ** big-endian integer which is the offset in the b-tree page of the next
+      ** freeblock in the chain, or zero if the freeblock is the last on the
+      ** chain. */
+      j = get2byte(&data[i]);
+      /* EVIDENCE-OF: R-06866-39125 Freeblocks are always connected in order of
+      ** increasing offset. */
+      assert( j==0 || j>i+size );  /* Enforced by btreeInitPage() */
+      assert( (u32)j<=usableSize-4 );   /* Enforced by btreeInitPage() */
+      i = j;
+    }
+    /* Analyze the min-heap looking for overlap between cells and/or 
+    ** freeblocks, and counting the number of untracked bytes in nFrag.
+    ** 
+    ** Each min-heap entry is of the form:    (start_address<<16)|end_address.
+    ** There is an implied first entry the covers the page header, the cell
+    ** pointer index, and the gap between the cell pointer index and the start
+    ** of cell content.  
+    **
+    ** The loop below pulls entries from the min-heap in order and compares
+    ** the start_address against the previous end_address.  If there is an
+    ** overlap, that means bytes are used multiple times.  If there is a gap,
+    ** that gap is added to the fragmentation count.
+    */
+    nFrag = 0;
+    prev = contentOffset - 1;   /* Implied first min-heap entry */
+    while( btreeHeapPull(heap,&x) ){
+      if( (prev&0xffff)>=(x>>16) ){
+        checkAppendMsg(pCheck,
+          "Multiple uses for byte %u of page %d", x>>16, iPage);
+        break;
+      }else{
+        nFrag += (x>>16) - (prev&0xffff) - 1;
+        prev = x;
+      }
+    }
+    nFrag += usableSize - (prev&0xffff) - 1;
+    /* EVIDENCE-OF: R-43263-13491 The total number of bytes in all fragments
+    ** is stored in the fifth field of the b-tree page header.
+    ** EVIDENCE-OF: R-07161-27322 The one-byte integer at offset 7 gives the
+    ** number of fragmented free bytes within the cell content area.
+    */
+    if( heap[0]==0 && nFrag!=data[hdr+7] ){
+      checkAppendMsg(pCheck,
+          "Fragmentation of %d bytes reported as %d on page %d",
+          nFrag, data[hdr+7], iPage);
+    }
+  }
+
+end_of_check:
+  if( !doCoverageCheck ) pPage->isInit = savedIsInit;
+  releasePage(pPage);
+  pCheck->zPfx = saved_zPfx;
+  pCheck->v1 = saved_v1;
+  pCheck->v2 = saved_v2;
+  return depth+1;
+}
+#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
+
+#ifndef SQLITE_OMIT_INTEGRITY_CHECK
+/*
+** This routine does a complete check of the given BTree file.  aRoot[] is
+** an array of pages numbers were each page number is the root page of
+** a table.  nRoot is the number of entries in aRoot.
+**
+** A read-only or read-write transaction must be opened before calling
+** this function.
+**
+** Write the number of error seen in *pnErr.  Except for some memory
+** allocation errors,  an error message held in memory obtained from
+** malloc is returned if *pnErr is non-zero.  If *pnErr==0 then NULL is
+** returned.  If a memory allocation error occurs, NULL is returned.
+*/
+SQLITE_PRIVATE char *sqlite3BtreeIntegrityCheck(
+  Btree *p,     /* The btree to be checked */
+  int *aRoot,   /* An array of root pages numbers for individual trees */
+  int nRoot,    /* Number of entries in aRoot[] */
+  int mxErr,    /* Stop reporting errors after this many */
+  int *pnErr    /* Write number of errors seen to this variable */
+){
+  Pgno i;
+  IntegrityCk sCheck;
+  BtShared *pBt = p->pBt;
+  int savedDbFlags = pBt->db->flags;
+  char zErr[100];
+  VVA_ONLY( int nRef );
+
+  sqlite3BtreeEnter(p);
+  assert( p->inTrans>TRANS_NONE && pBt->inTransaction>TRANS_NONE );
+  VVA_ONLY( nRef = sqlite3PagerRefcount(pBt->pPager) );
+  assert( nRef>=0 );
+  sCheck.pBt = pBt;
+  sCheck.pPager = pBt->pPager;
+  sCheck.nPage = btreePagecount(sCheck.pBt);
+  sCheck.mxErr = mxErr;
+  sCheck.nErr = 0;
+  sCheck.mallocFailed = 0;
+  sCheck.zPfx = 0;
+  sCheck.v1 = 0;
+  sCheck.v2 = 0;
+  sCheck.aPgRef = 0;
+  sCheck.heap = 0;
+  sqlite3StrAccumInit(&sCheck.errMsg, 0, zErr, sizeof(zErr), SQLITE_MAX_LENGTH);
+  sCheck.errMsg.printfFlags = SQLITE_PRINTF_INTERNAL;
+  if( sCheck.nPage==0 ){
+    goto integrity_ck_cleanup;
+  }
+
+  sCheck.aPgRef = sqlite3MallocZero((sCheck.nPage / 8)+ 1);
+  if( !sCheck.aPgRef ){
+    sCheck.mallocFailed = 1;
+    goto integrity_ck_cleanup;
+  }
+  sCheck.heap = (u32*)sqlite3PageMalloc( pBt->pageSize );
+  if( sCheck.heap==0 ){
+    sCheck.mallocFailed = 1;
+    goto integrity_ck_cleanup;
+  }
+
+  i = PENDING_BYTE_PAGE(pBt);
+  if( i<=sCheck.nPage ) setPageReferenced(&sCheck, i);
+
+  /* Check the integrity of the freelist
+  */
+  sCheck.zPfx = "Main freelist: ";
+  checkList(&sCheck, 1, get4byte(&pBt->pPage1->aData[32]),
+            get4byte(&pBt->pPage1->aData[36]));
+  sCheck.zPfx = 0;
+
+  /* Check all the tables.
+  */
+  testcase( pBt->db->flags & SQLITE_CellSizeCk );
+  pBt->db->flags &= ~SQLITE_CellSizeCk;
+  for(i=0; (int)i<nRoot && sCheck.mxErr; i++){
+    i64 notUsed;
+    if( aRoot[i]==0 ) continue;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    if( pBt->autoVacuum && aRoot[i]>1 ){
+      checkPtrmap(&sCheck, aRoot[i], PTRMAP_ROOTPAGE, 0);
+    }
+#endif
+    checkTreePage(&sCheck, aRoot[i], &notUsed, LARGEST_INT64);
+  }
+  pBt->db->flags = savedDbFlags;
+
+  /* Make sure every page in the file is referenced
+  */
+  for(i=1; i<=sCheck.nPage && sCheck.mxErr; i++){
+#ifdef SQLITE_OMIT_AUTOVACUUM
+    if( getPageReferenced(&sCheck, i)==0 ){
+      checkAppendMsg(&sCheck, "Page %d is never used", i);
+    }
+#else
+    /* If the database supports auto-vacuum, make sure no tables contain
+    ** references to pointer-map pages.
+    */
+    if( getPageReferenced(&sCheck, i)==0 && 
+       (PTRMAP_PAGENO(pBt, i)!=i || !pBt->autoVacuum) ){
+      checkAppendMsg(&sCheck, "Page %d is never used", i);
+    }
+    if( getPageReferenced(&sCheck, i)!=0 && 
+       (PTRMAP_PAGENO(pBt, i)==i && pBt->autoVacuum) ){
+      checkAppendMsg(&sCheck, "Pointer map page %d is referenced", i);
+    }
+#endif
+  }
+
+  /* Clean  up and report errors.
+  */
+integrity_ck_cleanup:
+  sqlite3PageFree(sCheck.heap);
+  sqlite3_free(sCheck.aPgRef);
+  if( sCheck.mallocFailed ){
+    sqlite3StrAccumReset(&sCheck.errMsg);
+    sCheck.nErr++;
+  }
+  *pnErr = sCheck.nErr;
+  if( sCheck.nErr==0 ) sqlite3StrAccumReset(&sCheck.errMsg);
+  /* Make sure this analysis did not leave any unref() pages. */
+  assert( nRef==sqlite3PagerRefcount(pBt->pPager) );
+  sqlite3BtreeLeave(p);
+  return sqlite3StrAccumFinish(&sCheck.errMsg);
+}
+#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
+
+/*
+** Return the full pathname of the underlying database file.  Return
+** an empty string if the database is in-memory or a TEMP database.
+**
+** The pager filename is invariant as long as the pager is
+** open so it is safe to access without the BtShared mutex.
+*/
+SQLITE_PRIVATE const char *sqlite3BtreeGetFilename(Btree *p){
+  assert( p->pBt->pPager!=0 );
+  return sqlite3PagerFilename(p->pBt->pPager, 1);
+}
+
+/*
+** Return the pathname of the journal file for this database. The return
+** value of this routine is the same regardless of whether the journal file
+** has been created or not.
+**
+** The pager journal filename is invariant as long as the pager is
+** open so it is safe to access without the BtShared mutex.
+*/
+SQLITE_PRIVATE const char *sqlite3BtreeGetJournalname(Btree *p){
+  assert( p->pBt->pPager!=0 );
+  return sqlite3PagerJournalname(p->pBt->pPager);
+}
+
+/*
+** Return non-zero if a transaction is active.
+*/
+SQLITE_PRIVATE int sqlite3BtreeIsInTrans(Btree *p){
+  assert( p==0 || sqlite3_mutex_held(p->db->mutex) );
+  return (p && (p->inTrans==TRANS_WRITE));
+}
+
+#ifndef SQLITE_OMIT_WAL
+/*
+** Run a checkpoint on the Btree passed as the first argument.
+**
+** Return SQLITE_LOCKED if this or any other connection has an open 
+** transaction on the shared-cache the argument Btree is connected to.
+**
+** Parameter eMode is one of SQLITE_CHECKPOINT_PASSIVE, FULL or RESTART.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCheckpoint(Btree *p, int eMode, int *pnLog, int *pnCkpt){
+  int rc = SQLITE_OK;
+  if( p ){
+    BtShared *pBt = p->pBt;
+    sqlite3BtreeEnter(p);
+    if( pBt->inTransaction!=TRANS_NONE ){
+      rc = SQLITE_LOCKED;
+    }else{
+      rc = sqlite3PagerCheckpoint(pBt->pPager, eMode, pnLog, pnCkpt);
+    }
+    sqlite3BtreeLeave(p);
+  }
+  return rc;
+}
+#endif
+
+/*
+** Return non-zero if a read (or write) transaction is active.
+*/
+SQLITE_PRIVATE int sqlite3BtreeIsInReadTrans(Btree *p){
+  assert( p );
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  return p->inTrans!=TRANS_NONE;
+}
+
+SQLITE_PRIVATE int sqlite3BtreeIsInBackup(Btree *p){
+  assert( p );
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  return p->nBackup!=0;
+}
+
+/*
+** This function returns a pointer to a blob of memory associated with
+** a single shared-btree. The memory is used by client code for its own
+** purposes (for example, to store a high-level schema associated with 
+** the shared-btree). The btree layer manages reference counting issues.
+**
+** The first time this is called on a shared-btree, nBytes bytes of memory
+** are allocated, zeroed, and returned to the caller. For each subsequent 
+** call the nBytes parameter is ignored and a pointer to the same blob
+** of memory returned. 
+**
+** If the nBytes parameter is 0 and the blob of memory has not yet been
+** allocated, a null pointer is returned. If the blob has already been
+** allocated, it is returned as normal.
+**
+** Just before the shared-btree is closed, the function passed as the 
+** xFree argument when the memory allocation was made is invoked on the 
+** blob of allocated memory. The xFree function should not call sqlite3_free()
+** on the memory, the btree layer does that.
+*/
+SQLITE_PRIVATE void *sqlite3BtreeSchema(Btree *p, int nBytes, void(*xFree)(void *)){
+  BtShared *pBt = p->pBt;
+  sqlite3BtreeEnter(p);
+  if( !pBt->pSchema && nBytes ){
+    pBt->pSchema = sqlite3DbMallocZero(0, nBytes);
+    pBt->xFreeSchema = xFree;
+  }
+  sqlite3BtreeLeave(p);
+  return pBt->pSchema;
+}
+
+/*
+** Return SQLITE_LOCKED_SHAREDCACHE if another user of the same shared 
+** btree as the argument handle holds an exclusive lock on the 
+** sqlite_master table. Otherwise SQLITE_OK.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSchemaLocked(Btree *p){
+  int rc;
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  sqlite3BtreeEnter(p);
+  rc = querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK);
+  assert( rc==SQLITE_OK || rc==SQLITE_LOCKED_SHAREDCACHE );
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+/*
+** Obtain a lock on the table whose root page is iTab.  The
+** lock is a write lock if isWritelock is true or a read lock
+** if it is false.
+*/
+SQLITE_PRIVATE int sqlite3BtreeLockTable(Btree *p, int iTab, u8 isWriteLock){
+  int rc = SQLITE_OK;
+  assert( p->inTrans!=TRANS_NONE );
+  if( p->sharable ){
+    u8 lockType = READ_LOCK + isWriteLock;
+    assert( READ_LOCK+1==WRITE_LOCK );
+    assert( isWriteLock==0 || isWriteLock==1 );
+
+    sqlite3BtreeEnter(p);
+    rc = querySharedCacheTableLock(p, iTab, lockType);
+    if( rc==SQLITE_OK ){
+      rc = setSharedCacheTableLock(p, iTab, lockType);
+    }
+    sqlite3BtreeLeave(p);
+  }
+  return rc;
+}
+#endif
+
+#ifndef SQLITE_OMIT_INCRBLOB
+/*
+** Argument pCsr must be a cursor opened for writing on an 
+** INTKEY table currently pointing at a valid table entry. 
+** This function modifies the data stored as part of that entry.
+**
+** Only the data content may only be modified, it is not possible to 
+** change the length of the data stored. If this function is called with
+** parameters that attempt to write past the end of the existing data,
+** no modifications are made and SQLITE_CORRUPT is returned.
+*/
+SQLITE_PRIVATE int sqlite3BtreePutData(BtCursor *pCsr, u32 offset, u32 amt, void *z){
+  int rc;
+  assert( cursorOwnsBtShared(pCsr) );
+  assert( sqlite3_mutex_held(pCsr->pBtree->db->mutex) );
+  assert( pCsr->curFlags & BTCF_Incrblob );
+
+  rc = restoreCursorPosition(pCsr);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+  assert( pCsr->eState!=CURSOR_REQUIRESEEK );
+  if( pCsr->eState!=CURSOR_VALID ){
+    return SQLITE_ABORT;
+  }
+
+  /* Save the positions of all other cursors open on this table. This is
+  ** required in case any of them are holding references to an xFetch
+  ** version of the b-tree page modified by the accessPayload call below.
+  **
+  ** Note that pCsr must be open on a INTKEY table and saveCursorPosition()
+  ** and hence saveAllCursors() cannot fail on a BTREE_INTKEY table, hence
+  ** saveAllCursors can only return SQLITE_OK.
+  */
+  VVA_ONLY(rc =) saveAllCursors(pCsr->pBt, pCsr->pgnoRoot, pCsr);
+  assert( rc==SQLITE_OK );
+
+  /* Check some assumptions: 
+  **   (a) the cursor is open for writing,
+  **   (b) there is a read/write transaction open,
+  **   (c) the connection holds a write-lock on the table (if required),
+  **   (d) there are no conflicting read-locks, and
+  **   (e) the cursor points at a valid row of an intKey table.
+  */
+  if( (pCsr->curFlags & BTCF_WriteFlag)==0 ){
+    return SQLITE_READONLY;
+  }
+  assert( (pCsr->pBt->btsFlags & BTS_READ_ONLY)==0
+              && pCsr->pBt->inTransaction==TRANS_WRITE );
+  assert( hasSharedCacheTableLock(pCsr->pBtree, pCsr->pgnoRoot, 0, 2) );
+  assert( !hasReadConflicts(pCsr->pBtree, pCsr->pgnoRoot) );
+  assert( pCsr->apPage[pCsr->iPage]->intKey );
+
+  return accessPayload(pCsr, offset, amt, (unsigned char *)z, 1);
+}
+
+/* 
+** Mark this cursor as an incremental blob cursor.
+*/
+SQLITE_PRIVATE void sqlite3BtreeIncrblobCursor(BtCursor *pCur){
+  pCur->curFlags |= BTCF_Incrblob;
+  pCur->pBtree->hasIncrblobCur = 1;
+}
+#endif
+
+/*
+** Set both the "read version" (single byte at byte offset 18) and 
+** "write version" (single byte at byte offset 19) fields in the database
+** header to iVersion.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSetVersion(Btree *pBtree, int iVersion){
+  BtShared *pBt = pBtree->pBt;
+  int rc;                         /* Return code */
+ 
+  assert( iVersion==1 || iVersion==2 );
+
+  /* If setting the version fields to 1, do not automatically open the
+  ** WAL connection, even if the version fields are currently set to 2.
+  */
+  pBt->btsFlags &= ~BTS_NO_WAL;
+  if( iVersion==1 ) pBt->btsFlags |= BTS_NO_WAL;
+
+  rc = sqlite3BtreeBeginTrans(pBtree, 0);
+  if( rc==SQLITE_OK ){
+    u8 *aData = pBt->pPage1->aData;
+    if( aData[18]!=(u8)iVersion || aData[19]!=(u8)iVersion ){
+      rc = sqlite3BtreeBeginTrans(pBtree, 2);
+      if( rc==SQLITE_OK ){
+        rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
+        if( rc==SQLITE_OK ){
+          aData[18] = (u8)iVersion;
+          aData[19] = (u8)iVersion;
+        }
+      }
+    }
+  }
+
+  pBt->btsFlags &= ~BTS_NO_WAL;
+  return rc;
+}
+
+/*
+** Return true if the cursor has a hint specified.  This routine is
+** only used from within assert() statements
+*/
+SQLITE_PRIVATE int sqlite3BtreeCursorHasHint(BtCursor *pCsr, unsigned int mask){
+  return (pCsr->hints & mask)!=0;
+}
+
+/*
+** Return true if the given Btree is read-only.
+*/
+SQLITE_PRIVATE int sqlite3BtreeIsReadonly(Btree *p){
+  return (p->pBt->btsFlags & BTS_READ_ONLY)!=0;
+}
+
+/*
+** Return the size of the header added to each page by this module.
+*/
+SQLITE_PRIVATE int sqlite3HeaderSizeBtree(void){ return ROUND8(sizeof(MemPage)); }
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE)
+/*
+** Return true if the Btree passed as the only argument is sharable.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSharable(Btree *p){
+  return p->sharable;
+}
+
+/*
+** Return the number of connections to the BtShared object accessed by
+** the Btree handle passed as the only argument. For private caches 
+** this is always 1. For shared caches it may be 1 or greater.
+*/
+SQLITE_PRIVATE int sqlite3BtreeConnectionCount(Btree *p){
+  testcase( p->sharable );
+  return p->pBt->nRef;
+}
+#endif
+
+/************** End of btree.c ***********************************************/
+/************** Begin file backup.c ******************************************/
+/*
+** 2009 January 28
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the implementation of the sqlite3_backup_XXX() 
+** API functions and the related features.
+*/
+/* #include "sqliteInt.h" */
+/* #include "btreeInt.h" */
+
+/*
+** Structure allocated for each backup operation.
+*/
+struct sqlite3_backup {
+  sqlite3* pDestDb;        /* Destination database handle */
+  Btree *pDest;            /* Destination b-tree file */
+  u32 iDestSchema;         /* Original schema cookie in destination */
+  int bDestLocked;         /* True once a write-transaction is open on pDest */
+
+  Pgno iNext;              /* Page number of the next source page to copy */
+  sqlite3* pSrcDb;         /* Source database handle */
+  Btree *pSrc;             /* Source b-tree file */
+
+  int rc;                  /* Backup process error code */
+
+  /* These two variables are set by every call to backup_step(). They are
+  ** read by calls to backup_remaining() and backup_pagecount().
+  */
+  Pgno nRemaining;         /* Number of pages left to copy */
+  Pgno nPagecount;         /* Total number of pages to copy */
+
+  int isAttached;          /* True once backup has been registered with pager */
+  sqlite3_backup *pNext;   /* Next backup associated with source pager */
+};
+
+/*
+** THREAD SAFETY NOTES:
+**
+**   Once it has been created using backup_init(), a single sqlite3_backup
+**   structure may be accessed via two groups of thread-safe entry points:
+**
+**     * Via the sqlite3_backup_XXX() API function backup_step() and 
+**       backup_finish(). Both these functions obtain the source database
+**       handle mutex and the mutex associated with the source BtShared 
+**       structure, in that order.
+**
+**     * Via the BackupUpdate() and BackupRestart() functions, which are
+**       invoked by the pager layer to report various state changes in
+**       the page cache associated with the source database. The mutex
+**       associated with the source database BtShared structure will always 
+**       be held when either of these functions are invoked.
+**
+**   The other sqlite3_backup_XXX() API functions, backup_remaining() and
+**   backup_pagecount() are not thread-safe functions. If they are called
+**   while some other thread is calling backup_step() or backup_finish(),
+**   the values returned may be invalid. There is no way for a call to
+**   BackupUpdate() or BackupRestart() to interfere with backup_remaining()
+**   or backup_pagecount().
+**
+**   Depending on the SQLite configuration, the database handles and/or
+**   the Btree objects may have their own mutexes that require locking.
+**   Non-sharable Btrees (in-memory databases for example), do not have
+**   associated mutexes.
+*/
+
+/*
+** Return a pointer corresponding to database zDb (i.e. "main", "temp")
+** in connection handle pDb. If such a database cannot be found, return
+** a NULL pointer and write an error message to pErrorDb.
+**
+** If the "temp" database is requested, it may need to be opened by this 
+** function. If an error occurs while doing so, return 0 and write an 
+** error message to pErrorDb.
+*/
+static Btree *findBtree(sqlite3 *pErrorDb, sqlite3 *pDb, const char *zDb){
+  int i = sqlite3FindDbName(pDb, zDb);
+
+  if( i==1 ){
+    Parse sParse;
+    int rc = 0;
+    memset(&sParse, 0, sizeof(sParse));
+    sParse.db = pDb;
+    if( sqlite3OpenTempDatabase(&sParse) ){
+      sqlite3ErrorWithMsg(pErrorDb, sParse.rc, "%s", sParse.zErrMsg);
+      rc = SQLITE_ERROR;
+    }
+    sqlite3DbFree(pErrorDb, sParse.zErrMsg);
+    sqlite3ParserReset(&sParse);
+    if( rc ){
+      return 0;
+    }
+  }
+
+  if( i<0 ){
+    sqlite3ErrorWithMsg(pErrorDb, SQLITE_ERROR, "unknown database %s", zDb);
+    return 0;
+  }
+
+  return pDb->aDb[i].pBt;
+}
+
+/*
+** Attempt to set the page size of the destination to match the page size
+** of the source.
+*/
+static int setDestPgsz(sqlite3_backup *p){
+  int rc;
+  rc = sqlite3BtreeSetPageSize(p->pDest,sqlite3BtreeGetPageSize(p->pSrc),-1,0);
+  return rc;
+}
+
+/*
+** Check that there is no open read-transaction on the b-tree passed as the
+** second argument. If there is not, return SQLITE_OK. Otherwise, if there
+** is an open read-transaction, return SQLITE_ERROR and leave an error 
+** message in database handle db.
+*/
+static int checkReadTransaction(sqlite3 *db, Btree *p){
+  if( sqlite3BtreeIsInReadTrans(p) ){
+    sqlite3ErrorWithMsg(db, SQLITE_ERROR, "destination database is in use");
+    return SQLITE_ERROR;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Create an sqlite3_backup process to copy the contents of zSrcDb from
+** connection handle pSrcDb to zDestDb in pDestDb. If successful, return
+** a pointer to the new sqlite3_backup object.
+**
+** If an error occurs, NULL is returned and an error code and error message
+** stored in database handle pDestDb.
+*/
+SQLITE_API sqlite3_backup *sqlite3_backup_init(
+  sqlite3* pDestDb,                     /* Database to write to */
+  const char *zDestDb,                  /* Name of database within pDestDb */
+  sqlite3* pSrcDb,                      /* Database connection to read from */
+  const char *zSrcDb                    /* Name of database within pSrcDb */
+){
+  sqlite3_backup *p;                    /* Value to return */
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(pSrcDb)||!sqlite3SafetyCheckOk(pDestDb) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+
+  /* Lock the source database handle. The destination database
+  ** handle is not locked in this routine, but it is locked in
+  ** sqlite3_backup_step(). The user is required to ensure that no
+  ** other thread accesses the destination handle for the duration
+  ** of the backup operation.  Any attempt to use the destination
+  ** database connection while a backup is in progress may cause
+  ** a malfunction or a deadlock.
+  */
+  sqlite3_mutex_enter(pSrcDb->mutex);
+  sqlite3_mutex_enter(pDestDb->mutex);
+
+  if( pSrcDb==pDestDb ){
+    sqlite3ErrorWithMsg(
+        pDestDb, SQLITE_ERROR, "source and destination must be distinct"
+    );
+    p = 0;
+  }else {
+    /* Allocate space for a new sqlite3_backup object...
+    ** EVIDENCE-OF: R-64852-21591 The sqlite3_backup object is created by a
+    ** call to sqlite3_backup_init() and is destroyed by a call to
+    ** sqlite3_backup_finish(). */
+    p = (sqlite3_backup *)sqlite3MallocZero(sizeof(sqlite3_backup));
+    if( !p ){
+      sqlite3Error(pDestDb, SQLITE_NOMEM_BKPT);
+    }
+  }
+
+  /* If the allocation succeeded, populate the new object. */
+  if( p ){
+    p->pSrc = findBtree(pDestDb, pSrcDb, zSrcDb);
+    p->pDest = findBtree(pDestDb, pDestDb, zDestDb);
+    p->pDestDb = pDestDb;
+    p->pSrcDb = pSrcDb;
+    p->iNext = 1;
+    p->isAttached = 0;
+
+    if( 0==p->pSrc || 0==p->pDest 
+     || checkReadTransaction(pDestDb, p->pDest)!=SQLITE_OK 
+     ){
+      /* One (or both) of the named databases did not exist or an OOM
+      ** error was hit. Or there is a transaction open on the destination
+      ** database. The error has already been written into the pDestDb 
+      ** handle. All that is left to do here is free the sqlite3_backup 
+      ** structure.  */
+      sqlite3_free(p);
+      p = 0;
+    }
+  }
+  if( p ){
+    p->pSrc->nBackup++;
+  }
+
+  sqlite3_mutex_leave(pDestDb->mutex);
+  sqlite3_mutex_leave(pSrcDb->mutex);
+  return p;
+}
+
+/*
+** Argument rc is an SQLite error code. Return true if this error is 
+** considered fatal if encountered during a backup operation. All errors
+** are considered fatal except for SQLITE_BUSY and SQLITE_LOCKED.
+*/
+static int isFatalError(int rc){
+  return (rc!=SQLITE_OK && rc!=SQLITE_BUSY && ALWAYS(rc!=SQLITE_LOCKED));
+}
+
+/*
+** Parameter zSrcData points to a buffer containing the data for 
+** page iSrcPg from the source database. Copy this data into the 
+** destination database.
+*/
+static int backupOnePage(
+  sqlite3_backup *p,              /* Backup handle */
+  Pgno iSrcPg,                    /* Source database page to backup */
+  const u8 *zSrcData,             /* Source database page data */
+  int bUpdate                     /* True for an update, false otherwise */
+){
+  Pager * const pDestPager = sqlite3BtreePager(p->pDest);
+  const int nSrcPgsz = sqlite3BtreeGetPageSize(p->pSrc);
+  int nDestPgsz = sqlite3BtreeGetPageSize(p->pDest);
+  const int nCopy = MIN(nSrcPgsz, nDestPgsz);
+  const i64 iEnd = (i64)iSrcPg*(i64)nSrcPgsz;
+#ifdef SQLITE_HAS_CODEC
+  /* Use BtreeGetReserveNoMutex() for the source b-tree, as although it is
+  ** guaranteed that the shared-mutex is held by this thread, handle
+  ** p->pSrc may not actually be the owner.  */
+  int nSrcReserve = sqlite3BtreeGetReserveNoMutex(p->pSrc);
+  int nDestReserve = sqlite3BtreeGetOptimalReserve(p->pDest);
+#endif
+  int rc = SQLITE_OK;
+  i64 iOff;
+
+  assert( sqlite3BtreeGetReserveNoMutex(p->pSrc)>=0 );
+  assert( p->bDestLocked );
+  assert( !isFatalError(p->rc) );
+  assert( iSrcPg!=PENDING_BYTE_PAGE(p->pSrc->pBt) );
+  assert( zSrcData );
+
+  /* Catch the case where the destination is an in-memory database and the
+  ** page sizes of the source and destination differ. 
+  */
+  if( nSrcPgsz!=nDestPgsz && sqlite3PagerIsMemdb(pDestPager) ){
+    rc = SQLITE_READONLY;
+  }
+
+#ifdef SQLITE_HAS_CODEC
+  /* Backup is not possible if the page size of the destination is changing
+  ** and a codec is in use.
+  */
+  if( nSrcPgsz!=nDestPgsz && sqlite3PagerGetCodec(pDestPager)!=0 ){
+    rc = SQLITE_READONLY;
+  }
+
+  /* Backup is not possible if the number of bytes of reserve space differ
+  ** between source and destination.  If there is a difference, try to
+  ** fix the destination to agree with the source.  If that is not possible,
+  ** then the backup cannot proceed.
+  */
+  if( nSrcReserve!=nDestReserve ){
+    u32 newPgsz = nSrcPgsz;
+    rc = sqlite3PagerSetPagesize(pDestPager, &newPgsz, nSrcReserve);
+    if( rc==SQLITE_OK && newPgsz!=nSrcPgsz ) rc = SQLITE_READONLY;
+  }
+#endif
+
+  /* This loop runs once for each destination page spanned by the source 
+  ** page. For each iteration, variable iOff is set to the byte offset
+  ** of the destination page.
+  */
+  for(iOff=iEnd-(i64)nSrcPgsz; rc==SQLITE_OK && iOff<iEnd; iOff+=nDestPgsz){
+    DbPage *pDestPg = 0;
+    Pgno iDest = (Pgno)(iOff/nDestPgsz)+1;
+    if( iDest==PENDING_BYTE_PAGE(p->pDest->pBt) ) continue;
+    if( SQLITE_OK==(rc = sqlite3PagerGet(pDestPager, iDest, &pDestPg, 0))
+     && SQLITE_OK==(rc = sqlite3PagerWrite(pDestPg))
+    ){
+      const u8 *zIn = &zSrcData[iOff%nSrcPgsz];
+      u8 *zDestData = sqlite3PagerGetData(pDestPg);
+      u8 *zOut = &zDestData[iOff%nDestPgsz];
+
+      /* Copy the data from the source page into the destination page.
+      ** Then clear the Btree layer MemPage.isInit flag. Both this module
+      ** and the pager code use this trick (clearing the first byte
+      ** of the page 'extra' space to invalidate the Btree layers
+      ** cached parse of the page). MemPage.isInit is marked 
+      ** "MUST BE FIRST" for this purpose.
+      */
+      memcpy(zOut, zIn, nCopy);
+      ((u8 *)sqlite3PagerGetExtra(pDestPg))[0] = 0;
+      if( iOff==0 && bUpdate==0 ){
+        sqlite3Put4byte(&zOut[28], sqlite3BtreeLastPage(p->pSrc));
+      }
+    }
+    sqlite3PagerUnref(pDestPg);
+  }
+
+  return rc;
+}
+
+/*
+** If pFile is currently larger than iSize bytes, then truncate it to
+** exactly iSize bytes. If pFile is not larger than iSize bytes, then
+** this function is a no-op.
+**
+** Return SQLITE_OK if everything is successful, or an SQLite error 
+** code if an error occurs.
+*/
+static int backupTruncateFile(sqlite3_file *pFile, i64 iSize){
+  i64 iCurrent;
+  int rc = sqlite3OsFileSize(pFile, &iCurrent);
+  if( rc==SQLITE_OK && iCurrent>iSize ){
+    rc = sqlite3OsTruncate(pFile, iSize);
+  }
+  return rc;
+}
+
+/*
+** Register this backup object with the associated source pager for
+** callbacks when pages are changed or the cache invalidated.
+*/
+static void attachBackupObject(sqlite3_backup *p){
+  sqlite3_backup **pp;
+  assert( sqlite3BtreeHoldsMutex(p->pSrc) );
+  pp = sqlite3PagerBackupPtr(sqlite3BtreePager(p->pSrc));
+  p->pNext = *pp;
+  *pp = p;
+  p->isAttached = 1;
+}
+
+/*
+** Copy nPage pages from the source b-tree to the destination.
+*/
+SQLITE_API int sqlite3_backup_step(sqlite3_backup *p, int nPage){
+  int rc;
+  int destMode;       /* Destination journal mode */
+  int pgszSrc = 0;    /* Source page size */
+  int pgszDest = 0;   /* Destination page size */
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( p==0 ) return SQLITE_MISUSE_BKPT;
+#endif
+  sqlite3_mutex_enter(p->pSrcDb->mutex);
+  sqlite3BtreeEnter(p->pSrc);
+  if( p->pDestDb ){
+    sqlite3_mutex_enter(p->pDestDb->mutex);
+  }
+
+  rc = p->rc;
+  if( !isFatalError(rc) ){
+    Pager * const pSrcPager = sqlite3BtreePager(p->pSrc);     /* Source pager */
+    Pager * const pDestPager = sqlite3BtreePager(p->pDest);   /* Dest pager */
+    int ii;                            /* Iterator variable */
+    int nSrcPage = -1;                 /* Size of source db in pages */
+    int bCloseTrans = 0;               /* True if src db requires unlocking */
+
+    /* If the source pager is currently in a write-transaction, return
+    ** SQLITE_BUSY immediately.
+    */
+    if( p->pDestDb && p->pSrc->pBt->inTransaction==TRANS_WRITE ){
+      rc = SQLITE_BUSY;
+    }else{
+      rc = SQLITE_OK;
+    }
+
+    /* If there is no open read-transaction on the source database, open
+    ** one now. If a transaction is opened here, then it will be closed
+    ** before this function exits.
+    */
+    if( rc==SQLITE_OK && 0==sqlite3BtreeIsInReadTrans(p->pSrc) ){
+      rc = sqlite3BtreeBeginTrans(p->pSrc, 0);
+      bCloseTrans = 1;
+    }
+
+    /* If the destination database has not yet been locked (i.e. if this
+    ** is the first call to backup_step() for the current backup operation),
+    ** try to set its page size to the same as the source database. This
+    ** is especially important on ZipVFS systems, as in that case it is
+    ** not possible to create a database file that uses one page size by
+    ** writing to it with another.  */
+    if( p->bDestLocked==0 && rc==SQLITE_OK && setDestPgsz(p)==SQLITE_NOMEM ){
+      rc = SQLITE_NOMEM;
+    }
+
+    /* Lock the destination database, if it is not locked already. */
+    if( SQLITE_OK==rc && p->bDestLocked==0
+     && SQLITE_OK==(rc = sqlite3BtreeBeginTrans(p->pDest, 2)) 
+    ){
+      p->bDestLocked = 1;
+      sqlite3BtreeGetMeta(p->pDest, BTREE_SCHEMA_VERSION, &p->iDestSchema);
+    }
+
+    /* Do not allow backup if the destination database is in WAL mode
+    ** and the page sizes are different between source and destination */
+    pgszSrc = sqlite3BtreeGetPageSize(p->pSrc);
+    pgszDest = sqlite3BtreeGetPageSize(p->pDest);
+    destMode = sqlite3PagerGetJournalMode(sqlite3BtreePager(p->pDest));
+    if( SQLITE_OK==rc && destMode==PAGER_JOURNALMODE_WAL && pgszSrc!=pgszDest ){
+      rc = SQLITE_READONLY;
+    }
+  
+    /* Now that there is a read-lock on the source database, query the
+    ** source pager for the number of pages in the database.
+    */
+    nSrcPage = (int)sqlite3BtreeLastPage(p->pSrc);
+    assert( nSrcPage>=0 );
+    for(ii=0; (nPage<0 || ii<nPage) && p->iNext<=(Pgno)nSrcPage && !rc; ii++){
+      const Pgno iSrcPg = p->iNext;                 /* Source page number */
+      if( iSrcPg!=PENDING_BYTE_PAGE(p->pSrc->pBt) ){
+        DbPage *pSrcPg;                             /* Source page object */
+        rc = sqlite3PagerGet(pSrcPager, iSrcPg, &pSrcPg,PAGER_GET_READONLY);
+        if( rc==SQLITE_OK ){
+          rc = backupOnePage(p, iSrcPg, sqlite3PagerGetData(pSrcPg), 0);
+          sqlite3PagerUnref(pSrcPg);
+        }
+      }
+      p->iNext++;
+    }
+    if( rc==SQLITE_OK ){
+      p->nPagecount = nSrcPage;
+      p->nRemaining = nSrcPage+1-p->iNext;
+      if( p->iNext>(Pgno)nSrcPage ){
+        rc = SQLITE_DONE;
+      }else if( !p->isAttached ){
+        attachBackupObject(p);
+      }
+    }
+  
+    /* Update the schema version field in the destination database. This
+    ** is to make sure that the schema-version really does change in
+    ** the case where the source and destination databases have the
+    ** same schema version.
+    */
+    if( rc==SQLITE_DONE ){
+      if( nSrcPage==0 ){
+        rc = sqlite3BtreeNewDb(p->pDest);
+        nSrcPage = 1;
+      }
+      if( rc==SQLITE_OK || rc==SQLITE_DONE ){
+        rc = sqlite3BtreeUpdateMeta(p->pDest,1,p->iDestSchema+1);
+      }
+      if( rc==SQLITE_OK ){
+        if( p->pDestDb ){
+          sqlite3ResetAllSchemasOfConnection(p->pDestDb);
+        }
+        if( destMode==PAGER_JOURNALMODE_WAL ){
+          rc = sqlite3BtreeSetVersion(p->pDest, 2);
+        }
+      }
+      if( rc==SQLITE_OK ){
+        int nDestTruncate;
+        /* Set nDestTruncate to the final number of pages in the destination
+        ** database. The complication here is that the destination page
+        ** size may be different to the source page size. 
+        **
+        ** If the source page size is smaller than the destination page size, 
+        ** round up. In this case the call to sqlite3OsTruncate() below will
+        ** fix the size of the file. However it is important to call
+        ** sqlite3PagerTruncateImage() here so that any pages in the 
+        ** destination file that lie beyond the nDestTruncate page mark are
+        ** journalled by PagerCommitPhaseOne() before they are destroyed
+        ** by the file truncation.
+        */
+        assert( pgszSrc==sqlite3BtreeGetPageSize(p->pSrc) );
+        assert( pgszDest==sqlite3BtreeGetPageSize(p->pDest) );
+        if( pgszSrc<pgszDest ){
+          int ratio = pgszDest/pgszSrc;
+          nDestTruncate = (nSrcPage+ratio-1)/ratio;
+          if( nDestTruncate==(int)PENDING_BYTE_PAGE(p->pDest->pBt) ){
+            nDestTruncate--;
+          }
+        }else{
+          nDestTruncate = nSrcPage * (pgszSrc/pgszDest);
+        }
+        assert( nDestTruncate>0 );
+
+        if( pgszSrc<pgszDest ){
+          /* If the source page-size is smaller than the destination page-size,
+          ** two extra things may need to happen:
+          **
+          **   * The destination may need to be truncated, and
+          **
+          **   * Data stored on the pages immediately following the 
+          **     pending-byte page in the source database may need to be
+          **     copied into the destination database.
+          */
+          const i64 iSize = (i64)pgszSrc * (i64)nSrcPage;
+          sqlite3_file * const pFile = sqlite3PagerFile(pDestPager);
+          Pgno iPg;
+          int nDstPage;
+          i64 iOff;
+          i64 iEnd;
+
+          assert( pFile );
+          assert( nDestTruncate==0 
+              || (i64)nDestTruncate*(i64)pgszDest >= iSize || (
+                nDestTruncate==(int)(PENDING_BYTE_PAGE(p->pDest->pBt)-1)
+             && iSize>=PENDING_BYTE && iSize<=PENDING_BYTE+pgszDest
+          ));
+
+          /* This block ensures that all data required to recreate the original
+          ** database has been stored in the journal for pDestPager and the
+          ** journal synced to disk. So at this point we may safely modify
+          ** the database file in any way, knowing that if a power failure
+          ** occurs, the original database will be reconstructed from the 
+          ** journal file.  */
+          sqlite3PagerPagecount(pDestPager, &nDstPage);
+          for(iPg=nDestTruncate; rc==SQLITE_OK && iPg<=(Pgno)nDstPage; iPg++){
+            if( iPg!=PENDING_BYTE_PAGE(p->pDest->pBt) ){
+              DbPage *pPg;
+              rc = sqlite3PagerGet(pDestPager, iPg, &pPg, 0);
+              if( rc==SQLITE_OK ){
+                rc = sqlite3PagerWrite(pPg);
+                sqlite3PagerUnref(pPg);
+              }
+            }
+          }
+          if( rc==SQLITE_OK ){
+            rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 1);
+          }
+
+          /* Write the extra pages and truncate the database file as required */
+          iEnd = MIN(PENDING_BYTE + pgszDest, iSize);
+          for(
+            iOff=PENDING_BYTE+pgszSrc; 
+            rc==SQLITE_OK && iOff<iEnd; 
+            iOff+=pgszSrc
+          ){
+            PgHdr *pSrcPg = 0;
+            const Pgno iSrcPg = (Pgno)((iOff/pgszSrc)+1);
+            rc = sqlite3PagerGet(pSrcPager, iSrcPg, &pSrcPg, 0);
+            if( rc==SQLITE_OK ){
+              u8 *zData = sqlite3PagerGetData(pSrcPg);
+              rc = sqlite3OsWrite(pFile, zData, pgszSrc, iOff);
+            }
+            sqlite3PagerUnref(pSrcPg);
+          }
+          if( rc==SQLITE_OK ){
+            rc = backupTruncateFile(pFile, iSize);
+          }
+
+          /* Sync the database file to disk. */
+          if( rc==SQLITE_OK ){
+            rc = sqlite3PagerSync(pDestPager, 0);
+          }
+        }else{
+          sqlite3PagerTruncateImage(pDestPager, nDestTruncate);
+          rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 0);
+        }
+    
+        /* Finish committing the transaction to the destination database. */
+        if( SQLITE_OK==rc
+         && SQLITE_OK==(rc = sqlite3BtreeCommitPhaseTwo(p->pDest, 0))
+        ){
+          rc = SQLITE_DONE;
+        }
+      }
+    }
+  
+    /* If bCloseTrans is true, then this function opened a read transaction
+    ** on the source database. Close the read transaction here. There is
+    ** no need to check the return values of the btree methods here, as
+    ** "committing" a read-only transaction cannot fail.
+    */
+    if( bCloseTrans ){
+      TESTONLY( int rc2 );
+      TESTONLY( rc2  = ) sqlite3BtreeCommitPhaseOne(p->pSrc, 0);
+      TESTONLY( rc2 |= ) sqlite3BtreeCommitPhaseTwo(p->pSrc, 0);
+      assert( rc2==SQLITE_OK );
+    }
+  
+    if( rc==SQLITE_IOERR_NOMEM ){
+      rc = SQLITE_NOMEM_BKPT;
+    }
+    p->rc = rc;
+  }
+  if( p->pDestDb ){
+    sqlite3_mutex_leave(p->pDestDb->mutex);
+  }
+  sqlite3BtreeLeave(p->pSrc);
+  sqlite3_mutex_leave(p->pSrcDb->mutex);
+  return rc;
+}
+
+/*
+** Release all resources associated with an sqlite3_backup* handle.
+*/
+SQLITE_API int sqlite3_backup_finish(sqlite3_backup *p){
+  sqlite3_backup **pp;                 /* Ptr to head of pagers backup list */
+  sqlite3 *pSrcDb;                     /* Source database connection */
+  int rc;                              /* Value to return */
+
+  /* Enter the mutexes */
+  if( p==0 ) return SQLITE_OK;
+  pSrcDb = p->pSrcDb;
+  sqlite3_mutex_enter(pSrcDb->mutex);
+  sqlite3BtreeEnter(p->pSrc);
+  if( p->pDestDb ){
+    sqlite3_mutex_enter(p->pDestDb->mutex);
+  }
+
+  /* Detach this backup from the source pager. */
+  if( p->pDestDb ){
+    p->pSrc->nBackup--;
+  }
+  if( p->isAttached ){
+    pp = sqlite3PagerBackupPtr(sqlite3BtreePager(p->pSrc));
+    while( *pp!=p ){
+      pp = &(*pp)->pNext;
+    }
+    *pp = p->pNext;
+  }
+
+  /* If a transaction is still open on the Btree, roll it back. */
+  sqlite3BtreeRollback(p->pDest, SQLITE_OK, 0);
+
+  /* Set the error code of the destination database handle. */
+  rc = (p->rc==SQLITE_DONE) ? SQLITE_OK : p->rc;
+  if( p->pDestDb ){
+    sqlite3Error(p->pDestDb, rc);
+
+    /* Exit the mutexes and free the backup context structure. */
+    sqlite3LeaveMutexAndCloseZombie(p->pDestDb);
+  }
+  sqlite3BtreeLeave(p->pSrc);
+  if( p->pDestDb ){
+    /* EVIDENCE-OF: R-64852-21591 The sqlite3_backup object is created by a
+    ** call to sqlite3_backup_init() and is destroyed by a call to
+    ** sqlite3_backup_finish(). */
+    sqlite3_free(p);
+  }
+  sqlite3LeaveMutexAndCloseZombie(pSrcDb);
+  return rc;
+}
+
+/*
+** Return the number of pages still to be backed up as of the most recent
+** call to sqlite3_backup_step().
+*/
+SQLITE_API int sqlite3_backup_remaining(sqlite3_backup *p){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( p==0 ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  return p->nRemaining;
+}
+
+/*
+** Return the total number of pages in the source database as of the most 
+** recent call to sqlite3_backup_step().
+*/
+SQLITE_API int sqlite3_backup_pagecount(sqlite3_backup *p){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( p==0 ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  return p->nPagecount;
+}
+
+/*
+** This function is called after the contents of page iPage of the
+** source database have been modified. If page iPage has already been 
+** copied into the destination database, then the data written to the
+** destination is now invalidated. The destination copy of iPage needs
+** to be updated with the new data before the backup operation is
+** complete.
+**
+** It is assumed that the mutex associated with the BtShared object
+** corresponding to the source database is held when this function is
+** called.
+*/
+static SQLITE_NOINLINE void backupUpdate(
+  sqlite3_backup *p,
+  Pgno iPage,
+  const u8 *aData
+){
+  assert( p!=0 );
+  do{
+    assert( sqlite3_mutex_held(p->pSrc->pBt->mutex) );
+    if( !isFatalError(p->rc) && iPage<p->iNext ){
+      /* The backup process p has already copied page iPage. But now it
+      ** has been modified by a transaction on the source pager. Copy
+      ** the new data into the backup.
+      */
+      int rc;
+      assert( p->pDestDb );
+      sqlite3_mutex_enter(p->pDestDb->mutex);
+      rc = backupOnePage(p, iPage, aData, 1);
+      sqlite3_mutex_leave(p->pDestDb->mutex);
+      assert( rc!=SQLITE_BUSY && rc!=SQLITE_LOCKED );
+      if( rc!=SQLITE_OK ){
+        p->rc = rc;
+      }
+    }
+  }while( (p = p->pNext)!=0 );
+}
+SQLITE_PRIVATE void sqlite3BackupUpdate(sqlite3_backup *pBackup, Pgno iPage, const u8 *aData){
+  if( pBackup ) backupUpdate(pBackup, iPage, aData);
+}
+
+/*
+** Restart the backup process. This is called when the pager layer
+** detects that the database has been modified by an external database
+** connection. In this case there is no way of knowing which of the
+** pages that have been copied into the destination database are still 
+** valid and which are not, so the entire process needs to be restarted.
+**
+** It is assumed that the mutex associated with the BtShared object
+** corresponding to the source database is held when this function is
+** called.
+*/
+SQLITE_PRIVATE void sqlite3BackupRestart(sqlite3_backup *pBackup){
+  sqlite3_backup *p;                   /* Iterator variable */
+  for(p=pBackup; p; p=p->pNext){
+    assert( sqlite3_mutex_held(p->pSrc->pBt->mutex) );
+    p->iNext = 1;
+  }
+}
+
+#ifndef SQLITE_OMIT_VACUUM
+/*
+** Copy the complete content of pBtFrom into pBtTo.  A transaction
+** must be active for both files.
+**
+** The size of file pTo may be reduced by this operation. If anything 
+** goes wrong, the transaction on pTo is rolled back. If successful, the 
+** transaction is committed before returning.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCopyFile(Btree *pTo, Btree *pFrom){
+  int rc;
+  sqlite3_file *pFd;              /* File descriptor for database pTo */
+  sqlite3_backup b;
+  sqlite3BtreeEnter(pTo);
+  sqlite3BtreeEnter(pFrom);
+
+  assert( sqlite3BtreeIsInTrans(pTo) );
+  pFd = sqlite3PagerFile(sqlite3BtreePager(pTo));
+  if( pFd->pMethods ){
+    i64 nByte = sqlite3BtreeGetPageSize(pFrom)*(i64)sqlite3BtreeLastPage(pFrom);
+    rc = sqlite3OsFileControl(pFd, SQLITE_FCNTL_OVERWRITE, &nByte);
+    if( rc==SQLITE_NOTFOUND ) rc = SQLITE_OK;
+    if( rc ) goto copy_finished;
+  }
+
+  /* Set up an sqlite3_backup object. sqlite3_backup.pDestDb must be set
+  ** to 0. This is used by the implementations of sqlite3_backup_step()
+  ** and sqlite3_backup_finish() to detect that they are being called
+  ** from this function, not directly by the user.
+  */
+  memset(&b, 0, sizeof(b));
+  b.pSrcDb = pFrom->db;
+  b.pSrc = pFrom;
+  b.pDest = pTo;
+  b.iNext = 1;
+
+#ifdef SQLITE_HAS_CODEC
+  sqlite3PagerAlignReserve(sqlite3BtreePager(pTo), sqlite3BtreePager(pFrom));
+#endif
+
+  /* 0x7FFFFFFF is the hard limit for the number of pages in a database
+  ** file. By passing this as the number of pages to copy to
+  ** sqlite3_backup_step(), we can guarantee that the copy finishes 
+  ** within a single call (unless an error occurs). The assert() statement
+  ** checks this assumption - (p->rc) should be set to either SQLITE_DONE 
+  ** or an error code.  */
+  sqlite3_backup_step(&b, 0x7FFFFFFF);
+  assert( b.rc!=SQLITE_OK );
+
+  rc = sqlite3_backup_finish(&b);
+  if( rc==SQLITE_OK ){
+    pTo->pBt->btsFlags &= ~BTS_PAGESIZE_FIXED;
+  }else{
+    sqlite3PagerClearCache(sqlite3BtreePager(b.pDest));
+  }
+
+  assert( sqlite3BtreeIsInTrans(pTo)==0 );
+copy_finished:
+  sqlite3BtreeLeave(pFrom);
+  sqlite3BtreeLeave(pTo);
+  return rc;
+}
+#endif /* SQLITE_OMIT_VACUUM */
+
+/************** End of backup.c **********************************************/
+/************** Begin file vdbemem.c *****************************************/
+/*
+** 2004 May 26
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains code use to manipulate "Mem" structure.  A "Mem"
+** stores a single value in the VDBE.  Mem is an opaque structure visible
+** only within the VDBE.  Interface routines refer to a Mem using the
+** name sqlite_value
+*/
+/* #include "sqliteInt.h" */
+/* #include "vdbeInt.h" */
+
+#ifdef SQLITE_DEBUG
+/*
+** Check invariants on a Mem object.
+**
+** This routine is intended for use inside of assert() statements, like
+** this:    assert( sqlite3VdbeCheckMemInvariants(pMem) );
+*/
+SQLITE_PRIVATE int sqlite3VdbeCheckMemInvariants(Mem *p){
+  /* If MEM_Dyn is set then Mem.xDel!=0.  
+  ** Mem.xDel is might not be initialized if MEM_Dyn is clear.
+  */
+  assert( (p->flags & MEM_Dyn)==0 || p->xDel!=0 );
+
+  /* MEM_Dyn may only be set if Mem.szMalloc==0.  In this way we
+  ** ensure that if Mem.szMalloc>0 then it is safe to do
+  ** Mem.z = Mem.zMalloc without having to check Mem.flags&MEM_Dyn.
+  ** That saves a few cycles in inner loops. */
+  assert( (p->flags & MEM_Dyn)==0 || p->szMalloc==0 );
+
+  /* Cannot be both MEM_Int and MEM_Real at the same time */
+  assert( (p->flags & (MEM_Int|MEM_Real))!=(MEM_Int|MEM_Real) );
+
+  /* The szMalloc field holds the correct memory allocation size */
+  assert( p->szMalloc==0
+       || p->szMalloc==sqlite3DbMallocSize(p->db,p->zMalloc) );
+
+  /* If p holds a string or blob, the Mem.z must point to exactly
+  ** one of the following:
+  **
+  **   (1) Memory in Mem.zMalloc and managed by the Mem object
+  **   (2) Memory to be freed using Mem.xDel
+  **   (3) An ephemeral string or blob
+  **   (4) A static string or blob
+  */
+  if( (p->flags & (MEM_Str|MEM_Blob)) && p->n>0 ){
+    assert( 
+      ((p->szMalloc>0 && p->z==p->zMalloc)? 1 : 0) +
+      ((p->flags&MEM_Dyn)!=0 ? 1 : 0) +
+      ((p->flags&MEM_Ephem)!=0 ? 1 : 0) +
+      ((p->flags&MEM_Static)!=0 ? 1 : 0) == 1
+    );
+  }
+  return 1;
+}
+#endif
+
+
+/*
+** If pMem is an object with a valid string representation, this routine
+** ensures the internal encoding for the string representation is
+** 'desiredEnc', one of SQLITE_UTF8, SQLITE_UTF16LE or SQLITE_UTF16BE.
+**
+** If pMem is not a string object, or the encoding of the string
+** representation is already stored using the requested encoding, then this
+** routine is a no-op.
+**
+** SQLITE_OK is returned if the conversion is successful (or not required).
+** SQLITE_NOMEM may be returned if a malloc() fails during conversion
+** between formats.
+*/
+SQLITE_PRIVATE int sqlite3VdbeChangeEncoding(Mem *pMem, int desiredEnc){
+#ifndef SQLITE_OMIT_UTF16
+  int rc;
+#endif
+  assert( (pMem->flags&MEM_RowSet)==0 );
+  assert( desiredEnc==SQLITE_UTF8 || desiredEnc==SQLITE_UTF16LE
+           || desiredEnc==SQLITE_UTF16BE );
+  if( !(pMem->flags&MEM_Str) || pMem->enc==desiredEnc ){
+    return SQLITE_OK;
+  }
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+#ifdef SQLITE_OMIT_UTF16
+  return SQLITE_ERROR;
+#else
+
+  /* MemTranslate() may return SQLITE_OK or SQLITE_NOMEM. If NOMEM is returned,
+  ** then the encoding of the value may not have changed.
+  */
+  rc = sqlite3VdbeMemTranslate(pMem, (u8)desiredEnc);
+  assert(rc==SQLITE_OK    || rc==SQLITE_NOMEM);
+  assert(rc==SQLITE_OK    || pMem->enc!=desiredEnc);
+  assert(rc==SQLITE_NOMEM || pMem->enc==desiredEnc);
+  return rc;
+#endif
+}
+
+/*
+** Make sure pMem->z points to a writable allocation of at least 
+** min(n,32) bytes.
+**
+** If the bPreserve argument is true, then copy of the content of
+** pMem->z into the new allocation.  pMem must be either a string or
+** blob if bPreserve is true.  If bPreserve is false, any prior content
+** in pMem->z is discarded.
+*/
+SQLITE_PRIVATE SQLITE_NOINLINE int sqlite3VdbeMemGrow(Mem *pMem, int n, int bPreserve){
+  assert( sqlite3VdbeCheckMemInvariants(pMem) );
+  assert( (pMem->flags&MEM_RowSet)==0 );
+  testcase( pMem->db==0 );
+
+  /* If the bPreserve flag is set to true, then the memory cell must already
+  ** contain a valid string or blob value.  */
+  assert( bPreserve==0 || pMem->flags&(MEM_Blob|MEM_Str) );
+  testcase( bPreserve && pMem->z==0 );
+
+  assert( pMem->szMalloc==0
+       || pMem->szMalloc==sqlite3DbMallocSize(pMem->db, pMem->zMalloc) );
+  if( pMem->szMalloc<n ){
+    if( n<32 ) n = 32;
+    if( bPreserve && pMem->szMalloc>0 && pMem->z==pMem->zMalloc ){
+      pMem->z = pMem->zMalloc = sqlite3DbReallocOrFree(pMem->db, pMem->z, n);
+      bPreserve = 0;
+    }else{
+      if( pMem->szMalloc>0 ) sqlite3DbFree(pMem->db, pMem->zMalloc);
+      pMem->zMalloc = sqlite3DbMallocRaw(pMem->db, n);
+    }
+    if( pMem->zMalloc==0 ){
+      sqlite3VdbeMemSetNull(pMem);
+      pMem->z = 0;
+      pMem->szMalloc = 0;
+      return SQLITE_NOMEM_BKPT;
+    }else{
+      pMem->szMalloc = sqlite3DbMallocSize(pMem->db, pMem->zMalloc);
+    }
+  }
+
+  if( bPreserve && pMem->z && pMem->z!=pMem->zMalloc ){
+    memcpy(pMem->zMalloc, pMem->z, pMem->n);
+  }
+  if( (pMem->flags&MEM_Dyn)!=0 ){
+    assert( pMem->xDel!=0 && pMem->xDel!=SQLITE_DYNAMIC );
+    pMem->xDel((void *)(pMem->z));
+  }
+
+  pMem->z = pMem->zMalloc;
+  pMem->flags &= ~(MEM_Dyn|MEM_Ephem|MEM_Static);
+  return SQLITE_OK;
+}
+
+/*
+** Change the pMem->zMalloc allocation to be at least szNew bytes.
+** If pMem->zMalloc already meets or exceeds the requested size, this
+** routine is a no-op.
+**
+** Any prior string or blob content in the pMem object may be discarded.
+** The pMem->xDel destructor is called, if it exists.  Though MEM_Str
+** and MEM_Blob values may be discarded, MEM_Int, MEM_Real, and MEM_Null
+** values are preserved.
+**
+** Return SQLITE_OK on success or an error code (probably SQLITE_NOMEM)
+** if unable to complete the resizing.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemClearAndResize(Mem *pMem, int szNew){
+  assert( szNew>0 );
+  assert( (pMem->flags & MEM_Dyn)==0 || pMem->szMalloc==0 );
+  if( pMem->szMalloc<szNew ){
+    return sqlite3VdbeMemGrow(pMem, szNew, 0);
+  }
+  assert( (pMem->flags & MEM_Dyn)==0 );
+  pMem->z = pMem->zMalloc;
+  pMem->flags &= (MEM_Null|MEM_Int|MEM_Real);
+  return SQLITE_OK;
+}
+
+/*
+** Change pMem so that its MEM_Str or MEM_Blob value is stored in
+** MEM.zMalloc, where it can be safely written.
+**
+** Return SQLITE_OK on success or SQLITE_NOMEM if malloc fails.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemMakeWriteable(Mem *pMem){
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( (pMem->flags&MEM_RowSet)==0 );
+  if( (pMem->flags & (MEM_Str|MEM_Blob))!=0 ){
+    if( ExpandBlob(pMem) ) return SQLITE_NOMEM;
+    if( pMem->szMalloc==0 || pMem->z!=pMem->zMalloc ){
+      if( sqlite3VdbeMemGrow(pMem, pMem->n + 2, 1) ){
+        return SQLITE_NOMEM_BKPT;
+      }
+      pMem->z[pMem->n] = 0;
+      pMem->z[pMem->n+1] = 0;
+      pMem->flags |= MEM_Term;
+    }
+  }
+  pMem->flags &= ~MEM_Ephem;
+#ifdef SQLITE_DEBUG
+  pMem->pScopyFrom = 0;
+#endif
+
+  return SQLITE_OK;
+}
+
+/*
+** If the given Mem* has a zero-filled tail, turn it into an ordinary
+** blob stored in dynamically allocated space.
+*/
+#ifndef SQLITE_OMIT_INCRBLOB
+SQLITE_PRIVATE int sqlite3VdbeMemExpandBlob(Mem *pMem){
+  int nByte;
+  assert( pMem->flags & MEM_Zero );
+  assert( pMem->flags&MEM_Blob );
+  assert( (pMem->flags&MEM_RowSet)==0 );
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+
+  /* Set nByte to the number of bytes required to store the expanded blob. */
+  nByte = pMem->n + pMem->u.nZero;
+  if( nByte<=0 ){
+    nByte = 1;
+  }
+  if( sqlite3VdbeMemGrow(pMem, nByte, 1) ){
+    return SQLITE_NOMEM_BKPT;
+  }
+
+  memset(&pMem->z[pMem->n], 0, pMem->u.nZero);
+  pMem->n += pMem->u.nZero;
+  pMem->flags &= ~(MEM_Zero|MEM_Term);
+  return SQLITE_OK;
+}
+#endif
+
+/*
+** It is already known that pMem contains an unterminated string.
+** Add the zero terminator.
+*/
+static SQLITE_NOINLINE int vdbeMemAddTerminator(Mem *pMem){
+  if( sqlite3VdbeMemGrow(pMem, pMem->n+2, 1) ){
+    return SQLITE_NOMEM_BKPT;
+  }
+  pMem->z[pMem->n] = 0;
+  pMem->z[pMem->n+1] = 0;
+  pMem->flags |= MEM_Term;
+  return SQLITE_OK;
+}
+
+/*
+** Make sure the given Mem is \u0000 terminated.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemNulTerminate(Mem *pMem){
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  testcase( (pMem->flags & (MEM_Term|MEM_Str))==(MEM_Term|MEM_Str) );
+  testcase( (pMem->flags & (MEM_Term|MEM_Str))==0 );
+  if( (pMem->flags & (MEM_Term|MEM_Str))!=MEM_Str ){
+    return SQLITE_OK;   /* Nothing to do */
+  }else{
+    return vdbeMemAddTerminator(pMem);
+  }
+}
+
+/*
+** Add MEM_Str to the set of representations for the given Mem.  Numbers
+** are converted using sqlite3_snprintf().  Converting a BLOB to a string
+** is a no-op.
+**
+** Existing representations MEM_Int and MEM_Real are invalidated if
+** bForce is true but are retained if bForce is false.
+**
+** A MEM_Null value will never be passed to this function. This function is
+** used for converting values to text for returning to the user (i.e. via
+** sqlite3_value_text()), or for ensuring that values to be used as btree
+** keys are strings. In the former case a NULL pointer is returned the
+** user and the latter is an internal programming error.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemStringify(Mem *pMem, u8 enc, u8 bForce){
+  int fg = pMem->flags;
+  const int nByte = 32;
+
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( !(fg&MEM_Zero) );
+  assert( !(fg&(MEM_Str|MEM_Blob)) );
+  assert( fg&(MEM_Int|MEM_Real) );
+  assert( (pMem->flags&MEM_RowSet)==0 );
+  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
+
+
+  if( sqlite3VdbeMemClearAndResize(pMem, nByte) ){
+    pMem->enc = 0;
+    return SQLITE_NOMEM_BKPT;
+  }
+
+  /* For a Real or Integer, use sqlite3_snprintf() to produce the UTF-8
+  ** string representation of the value. Then, if the required encoding
+  ** is UTF-16le or UTF-16be do a translation.
+  ** 
+  ** FIX ME: It would be better if sqlite3_snprintf() could do UTF-16.
+  */
+  if( fg & MEM_Int ){
+    sqlite3_snprintf(nByte, pMem->z, "%lld", pMem->u.i);
+  }else{
+    assert( fg & MEM_Real );
+    sqlite3_snprintf(nByte, pMem->z, "%!.15g", pMem->u.r);
+  }
+  pMem->n = sqlite3Strlen30(pMem->z);
+  pMem->enc = SQLITE_UTF8;
+  pMem->flags |= MEM_Str|MEM_Term;
+  if( bForce ) pMem->flags &= ~(MEM_Int|MEM_Real);
+  sqlite3VdbeChangeEncoding(pMem, enc);
+  return SQLITE_OK;
+}
+
+/*
+** Memory cell pMem contains the context of an aggregate function.
+** This routine calls the finalize method for that function.  The
+** result of the aggregate is stored back into pMem.
+**
+** Return SQLITE_ERROR if the finalizer reports an error.  SQLITE_OK
+** otherwise.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemFinalize(Mem *pMem, FuncDef *pFunc){
+  int rc = SQLITE_OK;
+  if( ALWAYS(pFunc && pFunc->xFinalize) ){
+    sqlite3_context ctx;
+    Mem t;
+    assert( (pMem->flags & MEM_Null)!=0 || pFunc==pMem->u.pDef );
+    assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+    memset(&ctx, 0, sizeof(ctx));
+    memset(&t, 0, sizeof(t));
+    t.flags = MEM_Null;
+    t.db = pMem->db;
+    ctx.pOut = &t;
+    ctx.pMem = pMem;
+    ctx.pFunc = pFunc;
+    pFunc->xFinalize(&ctx); /* IMP: R-24505-23230 */
+    assert( (pMem->flags & MEM_Dyn)==0 );
+    if( pMem->szMalloc>0 ) sqlite3DbFree(pMem->db, pMem->zMalloc);
+    memcpy(pMem, &t, sizeof(t));
+    rc = ctx.isError;
+  }
+  return rc;
+}
+
+/*
+** If the memory cell contains a value that must be freed by
+** invoking the external callback in Mem.xDel, then this routine
+** will free that value.  It also sets Mem.flags to MEM_Null.
+**
+** This is a helper routine for sqlite3VdbeMemSetNull() and
+** for sqlite3VdbeMemRelease().  Use those other routines as the
+** entry point for releasing Mem resources.
+*/
+static SQLITE_NOINLINE void vdbeMemClearExternAndSetNull(Mem *p){
+  assert( p->db==0 || sqlite3_mutex_held(p->db->mutex) );
+  assert( VdbeMemDynamic(p) );
+  if( p->flags&MEM_Agg ){
+    sqlite3VdbeMemFinalize(p, p->u.pDef);
+    assert( (p->flags & MEM_Agg)==0 );
+    testcase( p->flags & MEM_Dyn );
+  }
+  if( p->flags&MEM_Dyn ){
+    assert( (p->flags&MEM_RowSet)==0 );
+    assert( p->xDel!=SQLITE_DYNAMIC && p->xDel!=0 );
+    p->xDel((void *)p->z);
+  }else if( p->flags&MEM_RowSet ){
+    sqlite3RowSetClear(p->u.pRowSet);
+  }else if( p->flags&MEM_Frame ){
+    VdbeFrame *pFrame = p->u.pFrame;
+    pFrame->pParent = pFrame->v->pDelFrame;
+    pFrame->v->pDelFrame = pFrame;
+  }
+  p->flags = MEM_Null;
+}
+
+/*
+** Release memory held by the Mem p, both external memory cleared
+** by p->xDel and memory in p->zMalloc.
+**
+** This is a helper routine invoked by sqlite3VdbeMemRelease() in
+** the unusual case where there really is memory in p that needs
+** to be freed.
+*/
+static SQLITE_NOINLINE void vdbeMemClear(Mem *p){
+  if( VdbeMemDynamic(p) ){
+    vdbeMemClearExternAndSetNull(p);
+  }
+  if( p->szMalloc ){
+    sqlite3DbFree(p->db, p->zMalloc);
+    p->szMalloc = 0;
+  }
+  p->z = 0;
+}
+
+/*
+** Release any memory resources held by the Mem.  Both the memory that is
+** free by Mem.xDel and the Mem.zMalloc allocation are freed.
+**
+** Use this routine prior to clean up prior to abandoning a Mem, or to
+** reset a Mem back to its minimum memory utilization.
+**
+** Use sqlite3VdbeMemSetNull() to release just the Mem.xDel space
+** prior to inserting new content into the Mem.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemRelease(Mem *p){
+  assert( sqlite3VdbeCheckMemInvariants(p) );
+  if( VdbeMemDynamic(p) || p->szMalloc ){
+    vdbeMemClear(p);
+  }
+}
+
+/*
+** Convert a 64-bit IEEE double into a 64-bit signed integer.
+** If the double is out of range of a 64-bit signed integer then
+** return the closest available 64-bit signed integer.
+*/
+static i64 doubleToInt64(double r){
+#ifdef SQLITE_OMIT_FLOATING_POINT
+  /* When floating-point is omitted, double and int64 are the same thing */
+  return r;
+#else
+  /*
+  ** Many compilers we encounter do not define constants for the
+  ** minimum and maximum 64-bit integers, or they define them
+  ** inconsistently.  And many do not understand the "LL" notation.
+  ** So we define our own static constants here using nothing
+  ** larger than a 32-bit integer constant.
+  */
+  static const i64 maxInt = LARGEST_INT64;
+  static const i64 minInt = SMALLEST_INT64;
+
+  if( r<=(double)minInt ){
+    return minInt;
+  }else if( r>=(double)maxInt ){
+    return maxInt;
+  }else{
+    return (i64)r;
+  }
+#endif
+}
+
+/*
+** Return some kind of integer value which is the best we can do
+** at representing the value that *pMem describes as an integer.
+** If pMem is an integer, then the value is exact.  If pMem is
+** a floating-point then the value returned is the integer part.
+** If pMem is a string or blob, then we make an attempt to convert
+** it into an integer and return that.  If pMem represents an
+** an SQL-NULL value, return 0.
+**
+** If pMem represents a string value, its encoding might be changed.
+*/
+SQLITE_PRIVATE i64 sqlite3VdbeIntValue(Mem *pMem){
+  int flags;
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
+  flags = pMem->flags;
+  if( flags & MEM_Int ){
+    return pMem->u.i;
+  }else if( flags & MEM_Real ){
+    return doubleToInt64(pMem->u.r);
+  }else if( flags & (MEM_Str|MEM_Blob) ){
+    i64 value = 0;
+    assert( pMem->z || pMem->n==0 );
+    sqlite3Atoi64(pMem->z, &value, pMem->n, pMem->enc);
+    return value;
+  }else{
+    return 0;
+  }
+}
+
+/*
+** Return the best representation of pMem that we can get into a
+** double.  If pMem is already a double or an integer, return its
+** value.  If it is a string or blob, try to convert it to a double.
+** If it is a NULL, return 0.0.
+*/
+SQLITE_PRIVATE double sqlite3VdbeRealValue(Mem *pMem){
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
+  if( pMem->flags & MEM_Real ){
+    return pMem->u.r;
+  }else if( pMem->flags & MEM_Int ){
+    return (double)pMem->u.i;
+  }else if( pMem->flags & (MEM_Str|MEM_Blob) ){
+    /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
+    double val = (double)0;
+    sqlite3AtoF(pMem->z, &val, pMem->n, pMem->enc);
+    return val;
+  }else{
+    /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
+    return (double)0;
+  }
+}
+
+/*
+** The MEM structure is already a MEM_Real.  Try to also make it a
+** MEM_Int if we can.
+*/
+SQLITE_PRIVATE void sqlite3VdbeIntegerAffinity(Mem *pMem){
+  i64 ix;
+  assert( pMem->flags & MEM_Real );
+  assert( (pMem->flags & MEM_RowSet)==0 );
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
+
+  ix = doubleToInt64(pMem->u.r);
+
+  /* Only mark the value as an integer if
+  **
+  **    (1) the round-trip conversion real->int->real is a no-op, and
+  **    (2) The integer is neither the largest nor the smallest
+  **        possible integer (ticket #3922)
+  **
+  ** The second and third terms in the following conditional enforces
+  ** the second condition under the assumption that addition overflow causes
+  ** values to wrap around.
+  */
+  if( pMem->u.r==ix && ix>SMALLEST_INT64 && ix<LARGEST_INT64 ){
+    pMem->u.i = ix;
+    MemSetTypeFlag(pMem, MEM_Int);
+  }
+}
+
+/*
+** Convert pMem to type integer.  Invalidate any prior representations.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemIntegerify(Mem *pMem){
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( (pMem->flags & MEM_RowSet)==0 );
+  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
+
+  pMem->u.i = sqlite3VdbeIntValue(pMem);
+  MemSetTypeFlag(pMem, MEM_Int);
+  return SQLITE_OK;
+}
+
+/*
+** Convert pMem so that it is of type MEM_Real.
+** Invalidate any prior representations.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemRealify(Mem *pMem){
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
+
+  pMem->u.r = sqlite3VdbeRealValue(pMem);
+  MemSetTypeFlag(pMem, MEM_Real);
+  return SQLITE_OK;
+}
+
+/*
+** Convert pMem so that it has types MEM_Real or MEM_Int or both.
+** Invalidate any prior representations.
+**
+** Every effort is made to force the conversion, even if the input
+** is a string that does not look completely like a number.  Convert
+** as much of the string as we can and ignore the rest.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemNumerify(Mem *pMem){
+  if( (pMem->flags & (MEM_Int|MEM_Real|MEM_Null))==0 ){
+    assert( (pMem->flags & (MEM_Blob|MEM_Str))!=0 );
+    assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+    if( 0==sqlite3Atoi64(pMem->z, &pMem->u.i, pMem->n, pMem->enc) ){
+      MemSetTypeFlag(pMem, MEM_Int);
+    }else{
+      pMem->u.r = sqlite3VdbeRealValue(pMem);
+      MemSetTypeFlag(pMem, MEM_Real);
+      sqlite3VdbeIntegerAffinity(pMem);
+    }
+  }
+  assert( (pMem->flags & (MEM_Int|MEM_Real|MEM_Null))!=0 );
+  pMem->flags &= ~(MEM_Str|MEM_Blob|MEM_Zero);
+  return SQLITE_OK;
+}
+
+/*
+** Cast the datatype of the value in pMem according to the affinity
+** "aff".  Casting is different from applying affinity in that a cast
+** is forced.  In other words, the value is converted into the desired
+** affinity even if that results in loss of data.  This routine is
+** used (for example) to implement the SQL "cast()" operator.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemCast(Mem *pMem, u8 aff, u8 encoding){
+  if( pMem->flags & MEM_Null ) return;
+  switch( aff ){
+    case SQLITE_AFF_BLOB: {   /* Really a cast to BLOB */
+      if( (pMem->flags & MEM_Blob)==0 ){
+        sqlite3ValueApplyAffinity(pMem, SQLITE_AFF_TEXT, encoding);
+        assert( pMem->flags & MEM_Str || pMem->db->mallocFailed );
+        if( pMem->flags & MEM_Str ) MemSetTypeFlag(pMem, MEM_Blob);
+      }else{
+        pMem->flags &= ~(MEM_TypeMask&~MEM_Blob);
+      }
+      break;
+    }
+    case SQLITE_AFF_NUMERIC: {
+      sqlite3VdbeMemNumerify(pMem);
+      break;
+    }
+    case SQLITE_AFF_INTEGER: {
+      sqlite3VdbeMemIntegerify(pMem);
+      break;
+    }
+    case SQLITE_AFF_REAL: {
+      sqlite3VdbeMemRealify(pMem);
+      break;
+    }
+    default: {
+      assert( aff==SQLITE_AFF_TEXT );
+      assert( MEM_Str==(MEM_Blob>>3) );
+      pMem->flags |= (pMem->flags&MEM_Blob)>>3;
+      sqlite3ValueApplyAffinity(pMem, SQLITE_AFF_TEXT, encoding);
+      assert( pMem->flags & MEM_Str || pMem->db->mallocFailed );
+      pMem->flags &= ~(MEM_Int|MEM_Real|MEM_Blob|MEM_Zero);
+      break;
+    }
+  }
+}
+
+/*
+** Initialize bulk memory to be a consistent Mem object.
+**
+** The minimum amount of initialization feasible is performed.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemInit(Mem *pMem, sqlite3 *db, u16 flags){
+  assert( (flags & ~MEM_TypeMask)==0 );
+  pMem->flags = flags;
+  pMem->db = db;
+  pMem->szMalloc = 0;
+}
+
+
+/*
+** Delete any previous value and set the value stored in *pMem to NULL.
+**
+** This routine calls the Mem.xDel destructor to dispose of values that
+** require the destructor.  But it preserves the Mem.zMalloc memory allocation.
+** To free all resources, use sqlite3VdbeMemRelease(), which both calls this
+** routine to invoke the destructor and deallocates Mem.zMalloc.
+**
+** Use this routine to reset the Mem prior to insert a new value.
+**
+** Use sqlite3VdbeMemRelease() to complete erase the Mem prior to abandoning it.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemSetNull(Mem *pMem){
+  if( VdbeMemDynamic(pMem) ){
+    vdbeMemClearExternAndSetNull(pMem);
+  }else{
+    pMem->flags = MEM_Null;
+  }
+}
+SQLITE_PRIVATE void sqlite3ValueSetNull(sqlite3_value *p){
+  sqlite3VdbeMemSetNull((Mem*)p); 
+}
+
+/*
+** Delete any previous value and set the value to be a BLOB of length
+** n containing all zeros.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemSetZeroBlob(Mem *pMem, int n){
+  sqlite3VdbeMemRelease(pMem);
+  pMem->flags = MEM_Blob|MEM_Zero;
+  pMem->n = 0;
+  if( n<0 ) n = 0;
+  pMem->u.nZero = n;
+  pMem->enc = SQLITE_UTF8;
+  pMem->z = 0;
+}
+
+/*
+** The pMem is known to contain content that needs to be destroyed prior
+** to a value change.  So invoke the destructor, then set the value to
+** a 64-bit integer.
+*/
+static SQLITE_NOINLINE void vdbeReleaseAndSetInt64(Mem *pMem, i64 val){
+  sqlite3VdbeMemSetNull(pMem);
+  pMem->u.i = val;
+  pMem->flags = MEM_Int;
+}
+
+/*
+** Delete any previous value and set the value stored in *pMem to val,
+** manifest type INTEGER.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemSetInt64(Mem *pMem, i64 val){
+  if( VdbeMemDynamic(pMem) ){
+    vdbeReleaseAndSetInt64(pMem, val);
+  }else{
+    pMem->u.i = val;
+    pMem->flags = MEM_Int;
+  }
+}
+
+#ifndef SQLITE_OMIT_FLOATING_POINT
+/*
+** Delete any previous value and set the value stored in *pMem to val,
+** manifest type REAL.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemSetDouble(Mem *pMem, double val){
+  sqlite3VdbeMemSetNull(pMem);
+  if( !sqlite3IsNaN(val) ){
+    pMem->u.r = val;
+    pMem->flags = MEM_Real;
+  }
+}
+#endif
+
+/*
+** Delete any previous value and set the value of pMem to be an
+** empty boolean index.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemSetRowSet(Mem *pMem){
+  sqlite3 *db = pMem->db;
+  assert( db!=0 );
+  assert( (pMem->flags & MEM_RowSet)==0 );
+  sqlite3VdbeMemRelease(pMem);
+  pMem->zMalloc = sqlite3DbMallocRawNN(db, 64);
+  if( db->mallocFailed ){
+    pMem->flags = MEM_Null;
+    pMem->szMalloc = 0;
+  }else{
+    assert( pMem->zMalloc );
+    pMem->szMalloc = sqlite3DbMallocSize(db, pMem->zMalloc);
+    pMem->u.pRowSet = sqlite3RowSetInit(db, pMem->zMalloc, pMem->szMalloc);
+    assert( pMem->u.pRowSet!=0 );
+    pMem->flags = MEM_RowSet;
+  }
+}
+
+/*
+** Return true if the Mem object contains a TEXT or BLOB that is
+** too large - whose size exceeds SQLITE_MAX_LENGTH.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemTooBig(Mem *p){
+  assert( p->db!=0 );
+  if( p->flags & (MEM_Str|MEM_Blob) ){
+    int n = p->n;
+    if( p->flags & MEM_Zero ){
+      n += p->u.nZero;
+    }
+    return n>p->db->aLimit[SQLITE_LIMIT_LENGTH];
+  }
+  return 0; 
+}
+
+#ifdef SQLITE_DEBUG
+/*
+** This routine prepares a memory cell for modification by breaking
+** its link to a shallow copy and by marking any current shallow
+** copies of this cell as invalid.
+**
+** This is used for testing and debugging only - to make sure shallow
+** copies are not misused.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemAboutToChange(Vdbe *pVdbe, Mem *pMem){
+  int i;
+  Mem *pX;
+  for(i=0, pX=pVdbe->aMem; i<pVdbe->nMem; i++, pX++){
+    if( pX->pScopyFrom==pMem ){
+      pX->flags |= MEM_Undefined;
+      pX->pScopyFrom = 0;
+    }
+  }
+  pMem->pScopyFrom = 0;
+}
+#endif /* SQLITE_DEBUG */
+
+
+/*
+** Make an shallow copy of pFrom into pTo.  Prior contents of
+** pTo are freed.  The pFrom->z field is not duplicated.  If
+** pFrom->z is used, then pTo->z points to the same thing as pFrom->z
+** and flags gets srcType (either MEM_Ephem or MEM_Static).
+*/
+static SQLITE_NOINLINE void vdbeClrCopy(Mem *pTo, const Mem *pFrom, int eType){
+  vdbeMemClearExternAndSetNull(pTo);
+  assert( !VdbeMemDynamic(pTo) );
+  sqlite3VdbeMemShallowCopy(pTo, pFrom, eType);
+}
+SQLITE_PRIVATE void sqlite3VdbeMemShallowCopy(Mem *pTo, const Mem *pFrom, int srcType){
+  assert( (pFrom->flags & MEM_RowSet)==0 );
+  assert( pTo->db==pFrom->db );
+  if( VdbeMemDynamic(pTo) ){ vdbeClrCopy(pTo,pFrom,srcType); return; }
+  memcpy(pTo, pFrom, MEMCELLSIZE);
+  if( (pFrom->flags&MEM_Static)==0 ){
+    pTo->flags &= ~(MEM_Dyn|MEM_Static|MEM_Ephem);
+    assert( srcType==MEM_Ephem || srcType==MEM_Static );
+    pTo->flags |= srcType;
+  }
+}
+
+/*
+** Make a full copy of pFrom into pTo.  Prior contents of pTo are
+** freed before the copy is made.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemCopy(Mem *pTo, const Mem *pFrom){
+  int rc = SQLITE_OK;
+
+  assert( (pFrom->flags & MEM_RowSet)==0 );
+  if( VdbeMemDynamic(pTo) ) vdbeMemClearExternAndSetNull(pTo);
+  memcpy(pTo, pFrom, MEMCELLSIZE);
+  pTo->flags &= ~MEM_Dyn;
+  if( pTo->flags&(MEM_Str|MEM_Blob) ){
+    if( 0==(pFrom->flags&MEM_Static) ){
+      pTo->flags |= MEM_Ephem;
+      rc = sqlite3VdbeMemMakeWriteable(pTo);
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Transfer the contents of pFrom to pTo. Any existing value in pTo is
+** freed. If pFrom contains ephemeral data, a copy is made.
+**
+** pFrom contains an SQL NULL when this routine returns.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemMove(Mem *pTo, Mem *pFrom){
+  assert( pFrom->db==0 || sqlite3_mutex_held(pFrom->db->mutex) );
+  assert( pTo->db==0 || sqlite3_mutex_held(pTo->db->mutex) );
+  assert( pFrom->db==0 || pTo->db==0 || pFrom->db==pTo->db );
+
+  sqlite3VdbeMemRelease(pTo);
+  memcpy(pTo, pFrom, sizeof(Mem));
+  pFrom->flags = MEM_Null;
+  pFrom->szMalloc = 0;
+}
+
+/*
+** Change the value of a Mem to be a string or a BLOB.
+**
+** The memory management strategy depends on the value of the xDel
+** parameter. If the value passed is SQLITE_TRANSIENT, then the 
+** string is copied into a (possibly existing) buffer managed by the 
+** Mem structure. Otherwise, any existing buffer is freed and the
+** pointer copied.
+**
+** If the string is too large (if it exceeds the SQLITE_LIMIT_LENGTH
+** size limit) then no memory allocation occurs.  If the string can be
+** stored without allocating memory, then it is.  If a memory allocation
+** is required to store the string, then value of pMem is unchanged.  In
+** either case, SQLITE_TOOBIG is returned.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemSetStr(
+  Mem *pMem,          /* Memory cell to set to string value */
+  const char *z,      /* String pointer */
+  int n,              /* Bytes in string, or negative */
+  u8 enc,             /* Encoding of z.  0 for BLOBs */
+  void (*xDel)(void*) /* Destructor function */
+){
+  int nByte = n;      /* New value for pMem->n */
+  int iLimit;         /* Maximum allowed string or blob size */
+  u16 flags = 0;      /* New value for pMem->flags */
+
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( (pMem->flags & MEM_RowSet)==0 );
+
+  /* If z is a NULL pointer, set pMem to contain an SQL NULL. */
+  if( !z ){
+    sqlite3VdbeMemSetNull(pMem);
+    return SQLITE_OK;
+  }
+
+  if( pMem->db ){
+    iLimit = pMem->db->aLimit[SQLITE_LIMIT_LENGTH];
+  }else{
+    iLimit = SQLITE_MAX_LENGTH;
+  }
+  flags = (enc==0?MEM_Blob:MEM_Str);
+  if( nByte<0 ){
+    assert( enc!=0 );
+    if( enc==SQLITE_UTF8 ){
+      nByte = sqlite3Strlen30(z);
+      if( nByte>iLimit ) nByte = iLimit+1;
+    }else{
+      for(nByte=0; nByte<=iLimit && (z[nByte] | z[nByte+1]); nByte+=2){}
+    }
+    flags |= MEM_Term;
+  }
+
+  /* The following block sets the new values of Mem.z and Mem.xDel. It
+  ** also sets a flag in local variable "flags" to indicate the memory
+  ** management (one of MEM_Dyn or MEM_Static).
+  */
+  if( xDel==SQLITE_TRANSIENT ){
+    int nAlloc = nByte;
+    if( flags&MEM_Term ){
+      nAlloc += (enc==SQLITE_UTF8?1:2);
+    }
+    if( nByte>iLimit ){
+      return SQLITE_TOOBIG;
+    }
+    testcase( nAlloc==0 );
+    testcase( nAlloc==31 );
+    testcase( nAlloc==32 );
+    if( sqlite3VdbeMemClearAndResize(pMem, MAX(nAlloc,32)) ){
+      return SQLITE_NOMEM_BKPT;
+    }
+    memcpy(pMem->z, z, nAlloc);
+  }else if( xDel==SQLITE_DYNAMIC ){
+    sqlite3VdbeMemRelease(pMem);
+    pMem->zMalloc = pMem->z = (char *)z;
+    pMem->szMalloc = sqlite3DbMallocSize(pMem->db, pMem->zMalloc);
+  }else{
+    sqlite3VdbeMemRelease(pMem);
+    pMem->z = (char *)z;
+    pMem->xDel = xDel;
+    flags |= ((xDel==SQLITE_STATIC)?MEM_Static:MEM_Dyn);
+  }
+
+  pMem->n = nByte;
+  pMem->flags = flags;
+  pMem->enc = (enc==0 ? SQLITE_UTF8 : enc);
+
+#ifndef SQLITE_OMIT_UTF16
+  if( pMem->enc!=SQLITE_UTF8 && sqlite3VdbeMemHandleBom(pMem) ){
+    return SQLITE_NOMEM_BKPT;
+  }
+#endif
+
+  if( nByte>iLimit ){
+    return SQLITE_TOOBIG;
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Move data out of a btree key or data field and into a Mem structure.
+** The data or key is taken from the entry that pCur is currently pointing
+** to.  offset and amt determine what portion of the data or key to retrieve.
+** key is true to get the key or false to get data.  The result is written
+** into the pMem element.
+**
+** The pMem object must have been initialized.  This routine will use
+** pMem->zMalloc to hold the content from the btree, if possible.  New
+** pMem->zMalloc space will be allocated if necessary.  The calling routine
+** is responsible for making sure that the pMem object is eventually
+** destroyed.
+**
+** If this routine fails for any reason (malloc returns NULL or unable
+** to read from the disk) then the pMem is left in an inconsistent state.
+*/
+static SQLITE_NOINLINE int vdbeMemFromBtreeResize(
+  BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
+  u32 offset,       /* Offset from the start of data to return bytes from. */
+  u32 amt,          /* Number of bytes to return. */
+  int key,          /* If true, retrieve from the btree key, not data. */
+  Mem *pMem         /* OUT: Return data in this Mem structure. */
+){
+  int rc;
+  pMem->flags = MEM_Null;
+  if( SQLITE_OK==(rc = sqlite3VdbeMemClearAndResize(pMem, amt+2)) ){
+    if( key ){
+      rc = sqlite3BtreeKey(pCur, offset, amt, pMem->z);
+    }else{
+      rc = sqlite3BtreeData(pCur, offset, amt, pMem->z);
+    }
+    if( rc==SQLITE_OK ){
+      pMem->z[amt] = 0;
+      pMem->z[amt+1] = 0;
+      pMem->flags = MEM_Blob|MEM_Term;
+      pMem->n = (int)amt;
+    }else{
+      sqlite3VdbeMemRelease(pMem);
+    }
+  }
+  return rc;
+}
+SQLITE_PRIVATE int sqlite3VdbeMemFromBtree(
+  BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
+  u32 offset,       /* Offset from the start of data to return bytes from. */
+  u32 amt,          /* Number of bytes to return. */
+  int key,          /* If true, retrieve from the btree key, not data. */
+  Mem *pMem         /* OUT: Return data in this Mem structure. */
+){
+  char *zData;        /* Data from the btree layer */
+  u32 available = 0;  /* Number of bytes available on the local btree page */
+  int rc = SQLITE_OK; /* Return code */
+
+  assert( sqlite3BtreeCursorIsValid(pCur) );
+  assert( !VdbeMemDynamic(pMem) );
+
+  /* Note: the calls to BtreeKeyFetch() and DataFetch() below assert() 
+  ** that both the BtShared and database handle mutexes are held. */
+  assert( (pMem->flags & MEM_RowSet)==0 );
+  zData = (char *)sqlite3BtreePayloadFetch(pCur, &available);
+  assert( zData!=0 );
+
+  if( offset+amt<=available ){
+    pMem->z = &zData[offset];
+    pMem->flags = MEM_Blob|MEM_Ephem;
+    pMem->n = (int)amt;
+  }else{
+    rc = vdbeMemFromBtreeResize(pCur, offset, amt, key, pMem);
+  }
+
+  return rc;
+}
+
+/*
+** The pVal argument is known to be a value other than NULL.
+** Convert it into a string with encoding enc and return a pointer
+** to a zero-terminated version of that string.
+*/
+static SQLITE_NOINLINE const void *valueToText(sqlite3_value* pVal, u8 enc){
+  assert( pVal!=0 );
+  assert( pVal->db==0 || sqlite3_mutex_held(pVal->db->mutex) );
+  assert( (enc&3)==(enc&~SQLITE_UTF16_ALIGNED) );
+  assert( (pVal->flags & MEM_RowSet)==0 );
+  assert( (pVal->flags & (MEM_Null))==0 );
+  if( pVal->flags & (MEM_Blob|MEM_Str) ){
+    pVal->flags |= MEM_Str;
+    if( pVal->enc != (enc & ~SQLITE_UTF16_ALIGNED) ){
+      sqlite3VdbeChangeEncoding(pVal, enc & ~SQLITE_UTF16_ALIGNED);
+    }
+    if( (enc & SQLITE_UTF16_ALIGNED)!=0 && 1==(1&SQLITE_PTR_TO_INT(pVal->z)) ){
+      assert( (pVal->flags & (MEM_Ephem|MEM_Static))!=0 );
+      if( sqlite3VdbeMemMakeWriteable(pVal)!=SQLITE_OK ){
+        return 0;
+      }
+    }
+    sqlite3VdbeMemNulTerminate(pVal); /* IMP: R-31275-44060 */
+  }else{
+    sqlite3VdbeMemStringify(pVal, enc, 0);
+    assert( 0==(1&SQLITE_PTR_TO_INT(pVal->z)) );
+  }
+  assert(pVal->enc==(enc & ~SQLITE_UTF16_ALIGNED) || pVal->db==0
+              || pVal->db->mallocFailed );
+  if( pVal->enc==(enc & ~SQLITE_UTF16_ALIGNED) ){
+    return pVal->z;
+  }else{
+    return 0;
+  }
+}
+
+/* This function is only available internally, it is not part of the
+** external API. It works in a similar way to sqlite3_value_text(),
+** except the data returned is in the encoding specified by the second
+** parameter, which must be one of SQLITE_UTF16BE, SQLITE_UTF16LE or
+** SQLITE_UTF8.
+**
+** (2006-02-16:)  The enc value can be or-ed with SQLITE_UTF16_ALIGNED.
+** If that is the case, then the result must be aligned on an even byte
+** boundary.
+*/
+SQLITE_PRIVATE const void *sqlite3ValueText(sqlite3_value* pVal, u8 enc){
+  if( !pVal ) return 0;
+  assert( pVal->db==0 || sqlite3_mutex_held(pVal->db->mutex) );
+  assert( (enc&3)==(enc&~SQLITE_UTF16_ALIGNED) );
+  assert( (pVal->flags & MEM_RowSet)==0 );
+  if( (pVal->flags&(MEM_Str|MEM_Term))==(MEM_Str|MEM_Term) && pVal->enc==enc ){
+    return pVal->z;
+  }
+  if( pVal->flags&MEM_Null ){
+    return 0;
+  }
+  return valueToText(pVal, enc);
+}
+
+/*
+** Create a new sqlite3_value object.
+*/
+SQLITE_PRIVATE sqlite3_value *sqlite3ValueNew(sqlite3 *db){
+  Mem *p = sqlite3DbMallocZero(db, sizeof(*p));
+  if( p ){
+    p->flags = MEM_Null;
+    p->db = db;
+  }
+  return p;
+}
+
+/*
+** Context object passed by sqlite3Stat4ProbeSetValue() through to 
+** valueNew(). See comments above valueNew() for details.
+*/
+struct ValueNewStat4Ctx {
+  Parse *pParse;
+  Index *pIdx;
+  UnpackedRecord **ppRec;
+  int iVal;
+};
+
+/*
+** Allocate and return a pointer to a new sqlite3_value object. If
+** the second argument to this function is NULL, the object is allocated
+** by calling sqlite3ValueNew().
+**
+** Otherwise, if the second argument is non-zero, then this function is 
+** being called indirectly by sqlite3Stat4ProbeSetValue(). If it has not
+** already been allocated, allocate the UnpackedRecord structure that 
+** that function will return to its caller here. Then return a pointer to
+** an sqlite3_value within the UnpackedRecord.a[] array.
+*/
+static sqlite3_value *valueNew(sqlite3 *db, struct ValueNewStat4Ctx *p){
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  if( p ){
+    UnpackedRecord *pRec = p->ppRec[0];
+
+    if( pRec==0 ){
+      Index *pIdx = p->pIdx;      /* Index being probed */
+      int nByte;                  /* Bytes of space to allocate */
+      int i;                      /* Counter variable */
+      int nCol = pIdx->nColumn;   /* Number of index columns including rowid */
+  
+      nByte = sizeof(Mem) * nCol + ROUND8(sizeof(UnpackedRecord));
+      pRec = (UnpackedRecord*)sqlite3DbMallocZero(db, nByte);
+      if( pRec ){
+        pRec->pKeyInfo = sqlite3KeyInfoOfIndex(p->pParse, pIdx);
+        if( pRec->pKeyInfo ){
+          assert( pRec->pKeyInfo->nField+pRec->pKeyInfo->nXField==nCol );
+          assert( pRec->pKeyInfo->enc==ENC(db) );
+          pRec->aMem = (Mem *)((u8*)pRec + ROUND8(sizeof(UnpackedRecord)));
+          for(i=0; i<nCol; i++){
+            pRec->aMem[i].flags = MEM_Null;
+            pRec->aMem[i].db = db;
+          }
+        }else{
+          sqlite3DbFree(db, pRec);
+          pRec = 0;
+        }
+      }
+      if( pRec==0 ) return 0;
+      p->ppRec[0] = pRec;
+    }
+  
+    pRec->nField = p->iVal+1;
+    return &pRec->aMem[p->iVal];
+  }
+#else
+  UNUSED_PARAMETER(p);
+#endif /* defined(SQLITE_ENABLE_STAT3_OR_STAT4) */
+  return sqlite3ValueNew(db);
+}
+
+/*
+** The expression object indicated by the second argument is guaranteed
+** to be a scalar SQL function. If
+**
+**   * all function arguments are SQL literals,
+**   * one of the SQLITE_FUNC_CONSTANT or _SLOCHNG function flags is set, and
+**   * the SQLITE_FUNC_NEEDCOLL function flag is not set,
+**
+** then this routine attempts to invoke the SQL function. Assuming no
+** error occurs, output parameter (*ppVal) is set to point to a value 
+** object containing the result before returning SQLITE_OK.
+**
+** Affinity aff is applied to the result of the function before returning.
+** If the result is a text value, the sqlite3_value object uses encoding 
+** enc.
+**
+** If the conditions above are not met, this function returns SQLITE_OK
+** and sets (*ppVal) to NULL. Or, if an error occurs, (*ppVal) is set to
+** NULL and an SQLite error code returned.
+*/
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+static int valueFromFunction(
+  sqlite3 *db,                    /* The database connection */
+  Expr *p,                        /* The expression to evaluate */
+  u8 enc,                         /* Encoding to use */
+  u8 aff,                         /* Affinity to use */
+  sqlite3_value **ppVal,          /* Write the new value here */
+  struct ValueNewStat4Ctx *pCtx   /* Second argument for valueNew() */
+){
+  sqlite3_context ctx;            /* Context object for function invocation */
+  sqlite3_value **apVal = 0;      /* Function arguments */
+  int nVal = 0;                   /* Size of apVal[] array */
+  FuncDef *pFunc = 0;             /* Function definition */
+  sqlite3_value *pVal = 0;        /* New value */
+  int rc = SQLITE_OK;             /* Return code */
+  ExprList *pList = 0;            /* Function arguments */
+  int i;                          /* Iterator variable */
+
+  assert( pCtx!=0 );
+  assert( (p->flags & EP_TokenOnly)==0 );
+  pList = p->x.pList;
+  if( pList ) nVal = pList->nExpr;
+  pFunc = sqlite3FindFunction(db, p->u.zToken, nVal, enc, 0);
+  assert( pFunc );
+  if( (pFunc->funcFlags & (SQLITE_FUNC_CONSTANT|SQLITE_FUNC_SLOCHNG))==0 
+   || (pFunc->funcFlags & SQLITE_FUNC_NEEDCOLL)
+  ){
+    return SQLITE_OK;
+  }
+
+  if( pList ){
+    apVal = (sqlite3_value**)sqlite3DbMallocZero(db, sizeof(apVal[0]) * nVal);
+    if( apVal==0 ){
+      rc = SQLITE_NOMEM_BKPT;
+      goto value_from_function_out;
+    }
+    for(i=0; i<nVal; i++){
+      rc = sqlite3ValueFromExpr(db, pList->a[i].pExpr, enc, aff, &apVal[i]);
+      if( apVal[i]==0 || rc!=SQLITE_OK ) goto value_from_function_out;
+    }
+  }
+
+  pVal = valueNew(db, pCtx);
+  if( pVal==0 ){
+    rc = SQLITE_NOMEM_BKPT;
+    goto value_from_function_out;
+  }
+
+  assert( pCtx->pParse->rc==SQLITE_OK );
+  memset(&ctx, 0, sizeof(ctx));
+  ctx.pOut = pVal;
+  ctx.pFunc = pFunc;
+  pFunc->xSFunc(&ctx, nVal, apVal);
+  if( ctx.isError ){
+    rc = ctx.isError;
+    sqlite3ErrorMsg(pCtx->pParse, "%s", sqlite3_value_text(pVal));
+  }else{
+    sqlite3ValueApplyAffinity(pVal, aff, SQLITE_UTF8);
+    assert( rc==SQLITE_OK );
+    rc = sqlite3VdbeChangeEncoding(pVal, enc);
+    if( rc==SQLITE_OK && sqlite3VdbeMemTooBig(pVal) ){
+      rc = SQLITE_TOOBIG;
+      pCtx->pParse->nErr++;
+    }
+  }
+  pCtx->pParse->rc = rc;
+
+ value_from_function_out:
+  if( rc!=SQLITE_OK ){
+    pVal = 0;
+  }
+  if( apVal ){
+    for(i=0; i<nVal; i++){
+      sqlite3ValueFree(apVal[i]);
+    }
+    sqlite3DbFree(db, apVal);
+  }
+
+  *ppVal = pVal;
+  return rc;
+}
+#else
+# define valueFromFunction(a,b,c,d,e,f) SQLITE_OK
+#endif /* defined(SQLITE_ENABLE_STAT3_OR_STAT4) */
+
+/*
+** Extract a value from the supplied expression in the manner described
+** above sqlite3ValueFromExpr(). Allocate the sqlite3_value object
+** using valueNew().
+**
+** If pCtx is NULL and an error occurs after the sqlite3_value object
+** has been allocated, it is freed before returning. Or, if pCtx is not
+** NULL, it is assumed that the caller will free any allocated object
+** in all cases.
+*/
+static int valueFromExpr(
+  sqlite3 *db,                    /* The database connection */
+  Expr *pExpr,                    /* The expression to evaluate */
+  u8 enc,                         /* Encoding to use */
+  u8 affinity,                    /* Affinity to use */
+  sqlite3_value **ppVal,          /* Write the new value here */
+  struct ValueNewStat4Ctx *pCtx   /* Second argument for valueNew() */
+){
+  int op;
+  char *zVal = 0;
+  sqlite3_value *pVal = 0;
+  int negInt = 1;
+  const char *zNeg = "";
+  int rc = SQLITE_OK;
+
+  assert( pExpr!=0 );
+  while( (op = pExpr->op)==TK_UPLUS || op==TK_SPAN ) pExpr = pExpr->pLeft;
+  if( NEVER(op==TK_REGISTER) ) op = pExpr->op2;
+
+  /* Compressed expressions only appear when parsing the DEFAULT clause
+  ** on a table column definition, and hence only when pCtx==0.  This
+  ** check ensures that an EP_TokenOnly expression is never passed down
+  ** into valueFromFunction(). */
+  assert( (pExpr->flags & EP_TokenOnly)==0 || pCtx==0 );
+
+  if( op==TK_CAST ){
+    u8 aff = sqlite3AffinityType(pExpr->u.zToken,0);
+    rc = valueFromExpr(db, pExpr->pLeft, enc, aff, ppVal, pCtx);
+    testcase( rc!=SQLITE_OK );
+    if( *ppVal ){
+      sqlite3VdbeMemCast(*ppVal, aff, SQLITE_UTF8);
+      sqlite3ValueApplyAffinity(*ppVal, affinity, SQLITE_UTF8);
+    }
+    return rc;
+  }
+
+  /* Handle negative integers in a single step.  This is needed in the
+  ** case when the value is -9223372036854775808.
+  */
+  if( op==TK_UMINUS
+   && (pExpr->pLeft->op==TK_INTEGER || pExpr->pLeft->op==TK_FLOAT) ){
+    pExpr = pExpr->pLeft;
+    op = pExpr->op;
+    negInt = -1;
+    zNeg = "-";
+  }
+
+  if( op==TK_STRING || op==TK_FLOAT || op==TK_INTEGER ){
+    pVal = valueNew(db, pCtx);
+    if( pVal==0 ) goto no_mem;
+    if( ExprHasProperty(pExpr, EP_IntValue) ){
+      sqlite3VdbeMemSetInt64(pVal, (i64)pExpr->u.iValue*negInt);
+    }else{
+      zVal = sqlite3MPrintf(db, "%s%s", zNeg, pExpr->u.zToken);
+      if( zVal==0 ) goto no_mem;
+      sqlite3ValueSetStr(pVal, -1, zVal, SQLITE_UTF8, SQLITE_DYNAMIC);
+    }
+    if( (op==TK_INTEGER || op==TK_FLOAT ) && affinity==SQLITE_AFF_BLOB ){
+      sqlite3ValueApplyAffinity(pVal, SQLITE_AFF_NUMERIC, SQLITE_UTF8);
+    }else{
+      sqlite3ValueApplyAffinity(pVal, affinity, SQLITE_UTF8);
+    }
+    if( pVal->flags & (MEM_Int|MEM_Real) ) pVal->flags &= ~MEM_Str;
+    if( enc!=SQLITE_UTF8 ){
+      rc = sqlite3VdbeChangeEncoding(pVal, enc);
+    }
+  }else if( op==TK_UMINUS ) {
+    /* This branch happens for multiple negative signs.  Ex: -(-5) */
+    if( SQLITE_OK==sqlite3ValueFromExpr(db,pExpr->pLeft,enc,affinity,&pVal) 
+     && pVal!=0
+    ){
+      sqlite3VdbeMemNumerify(pVal);
+      if( pVal->flags & MEM_Real ){
+        pVal->u.r = -pVal->u.r;
+      }else if( pVal->u.i==SMALLEST_INT64 ){
+        pVal->u.r = -(double)SMALLEST_INT64;
+        MemSetTypeFlag(pVal, MEM_Real);
+      }else{
+        pVal->u.i = -pVal->u.i;
+      }
+      sqlite3ValueApplyAffinity(pVal, affinity, enc);
+    }
+  }else if( op==TK_NULL ){
+    pVal = valueNew(db, pCtx);
+    if( pVal==0 ) goto no_mem;
+  }
+#ifndef SQLITE_OMIT_BLOB_LITERAL
+  else if( op==TK_BLOB ){
+    int nVal;
+    assert( pExpr->u.zToken[0]=='x' || pExpr->u.zToken[0]=='X' );
+    assert( pExpr->u.zToken[1]=='\'' );
+    pVal = valueNew(db, pCtx);
+    if( !pVal ) goto no_mem;
+    zVal = &pExpr->u.zToken[2];
+    nVal = sqlite3Strlen30(zVal)-1;
+    assert( zVal[nVal]=='\'' );
+    sqlite3VdbeMemSetStr(pVal, sqlite3HexToBlob(db, zVal, nVal), nVal/2,
+                         0, SQLITE_DYNAMIC);
+  }
+#endif
+
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  else if( op==TK_FUNCTION && pCtx!=0 ){
+    rc = valueFromFunction(db, pExpr, enc, affinity, &pVal, pCtx);
+  }
+#endif
+
+  *ppVal = pVal;
+  return rc;
+
+no_mem:
+  sqlite3OomFault(db);
+  sqlite3DbFree(db, zVal);
+  assert( *ppVal==0 );
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  if( pCtx==0 ) sqlite3ValueFree(pVal);
+#else
+  assert( pCtx==0 ); sqlite3ValueFree(pVal);
+#endif
+  return SQLITE_NOMEM_BKPT;
+}
+
+/*
+** Create a new sqlite3_value object, containing the value of pExpr.
+**
+** This only works for very simple expressions that consist of one constant
+** token (i.e. "5", "5.1", "'a string'"). If the expression can
+** be converted directly into a value, then the value is allocated and
+** a pointer written to *ppVal. The caller is responsible for deallocating
+** the value by passing it to sqlite3ValueFree() later on. If the expression
+** cannot be converted to a value, then *ppVal is set to NULL.
+*/
+SQLITE_PRIVATE int sqlite3ValueFromExpr(
+  sqlite3 *db,              /* The database connection */
+  Expr *pExpr,              /* The expression to evaluate */
+  u8 enc,                   /* Encoding to use */
+  u8 affinity,              /* Affinity to use */
+  sqlite3_value **ppVal     /* Write the new value here */
+){
+  return pExpr ? valueFromExpr(db, pExpr, enc, affinity, ppVal, 0) : 0;
+}
+
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+/*
+** The implementation of the sqlite_record() function. This function accepts
+** a single argument of any type. The return value is a formatted database 
+** record (a blob) containing the argument value.
+**
+** This is used to convert the value stored in the 'sample' column of the
+** sqlite_stat3 table to the record format SQLite uses internally.
+*/
+static void recordFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  const int file_format = 1;
+  u32 iSerial;                    /* Serial type */
+  int nSerial;                    /* Bytes of space for iSerial as varint */
+  u32 nVal;                       /* Bytes of space required for argv[0] */
+  int nRet;
+  sqlite3 *db;
+  u8 *aRet;
+
+  UNUSED_PARAMETER( argc );
+  iSerial = sqlite3VdbeSerialType(argv[0], file_format, &nVal);
+  nSerial = sqlite3VarintLen(iSerial);
+  db = sqlite3_context_db_handle(context);
+
+  nRet = 1 + nSerial + nVal;
+  aRet = sqlite3DbMallocRawNN(db, nRet);
+  if( aRet==0 ){
+    sqlite3_result_error_nomem(context);
+  }else{
+    aRet[0] = nSerial+1;
+    putVarint32(&aRet[1], iSerial);
+    sqlite3VdbeSerialPut(&aRet[1+nSerial], argv[0], iSerial);
+    sqlite3_result_blob(context, aRet, nRet, SQLITE_TRANSIENT);
+    sqlite3DbFree(db, aRet);
+  }
+}
+
+/*
+** Register built-in functions used to help read ANALYZE data.
+*/
+SQLITE_PRIVATE void sqlite3AnalyzeFunctions(void){
+  static FuncDef aAnalyzeTableFuncs[] = {
+    FUNCTION(sqlite_record,   1, 0, 0, recordFunc),
+  };
+  sqlite3InsertBuiltinFuncs(aAnalyzeTableFuncs, ArraySize(aAnalyzeTableFuncs));
+}
+
+/*
+** Attempt to extract a value from pExpr and use it to construct *ppVal.
+**
+** If pAlloc is not NULL, then an UnpackedRecord object is created for
+** pAlloc if one does not exist and the new value is added to the
+** UnpackedRecord object.
+**
+** A value is extracted in the following cases:
+**
+**  * (pExpr==0). In this case the value is assumed to be an SQL NULL,
+**
+**  * The expression is a bound variable, and this is a reprepare, or
+**
+**  * The expression is a literal value.
+**
+** On success, *ppVal is made to point to the extracted value.  The caller
+** is responsible for ensuring that the value is eventually freed.
+*/
+static int stat4ValueFromExpr(
+  Parse *pParse,                  /* Parse context */
+  Expr *pExpr,                    /* The expression to extract a value from */
+  u8 affinity,                    /* Affinity to use */
+  struct ValueNewStat4Ctx *pAlloc,/* How to allocate space.  Or NULL */
+  sqlite3_value **ppVal           /* OUT: New value object (or NULL) */
+){
+  int rc = SQLITE_OK;
+  sqlite3_value *pVal = 0;
+  sqlite3 *db = pParse->db;
+
+  /* Skip over any TK_COLLATE nodes */
+  pExpr = sqlite3ExprSkipCollate(pExpr);
+
+  if( !pExpr ){
+    pVal = valueNew(db, pAlloc);
+    if( pVal ){
+      sqlite3VdbeMemSetNull((Mem*)pVal);
+    }
+  }else if( pExpr->op==TK_VARIABLE
+        || NEVER(pExpr->op==TK_REGISTER && pExpr->op2==TK_VARIABLE)
+  ){
+    Vdbe *v;
+    int iBindVar = pExpr->iColumn;
+    sqlite3VdbeSetVarmask(pParse->pVdbe, iBindVar);
+    if( (v = pParse->pReprepare)!=0 ){
+      pVal = valueNew(db, pAlloc);
+      if( pVal ){
+        rc = sqlite3VdbeMemCopy((Mem*)pVal, &v->aVar[iBindVar-1]);
+        if( rc==SQLITE_OK ){
+          sqlite3ValueApplyAffinity(pVal, affinity, ENC(db));
+        }
+        pVal->db = pParse->db;
+      }
+    }
+  }else{
+    rc = valueFromExpr(db, pExpr, ENC(db), affinity, &pVal, pAlloc);
+  }
+
+  assert( pVal==0 || pVal->db==db );
+  *ppVal = pVal;
+  return rc;
+}
+
+/*
+** This function is used to allocate and populate UnpackedRecord 
+** structures intended to be compared against sample index keys stored 
+** in the sqlite_stat4 table.
+**
+** A single call to this function populates zero or more fields of the
+** record starting with field iVal (fields are numbered from left to
+** right starting with 0). A single field is populated if:
+**
+**  * (pExpr==0). In this case the value is assumed to be an SQL NULL,
+**
+**  * The expression is a bound variable, and this is a reprepare, or
+**
+**  * The sqlite3ValueFromExpr() function is able to extract a value 
+**    from the expression (i.e. the expression is a literal value).
+**
+** Or, if pExpr is a TK_VECTOR, one field is populated for each of the
+** vector components that match either of the two latter criteria listed
+** above.
+**
+** Before any value is appended to the record, the affinity of the 
+** corresponding column within index pIdx is applied to it. Before
+** this function returns, output parameter *pnExtract is set to the
+** number of values appended to the record.
+**
+** When this function is called, *ppRec must either point to an object
+** allocated by an earlier call to this function, or must be NULL. If it
+** is NULL and a value can be successfully extracted, a new UnpackedRecord
+** is allocated (and *ppRec set to point to it) before returning.
+**
+** Unless an error is encountered, SQLITE_OK is returned. It is not an
+** error if a value cannot be extracted from pExpr. If an error does
+** occur, an SQLite error code is returned.
+*/
+SQLITE_PRIVATE int sqlite3Stat4ProbeSetValue(
+  Parse *pParse,                  /* Parse context */
+  Index *pIdx,                    /* Index being probed */
+  UnpackedRecord **ppRec,         /* IN/OUT: Probe record */
+  Expr *pExpr,                    /* The expression to extract a value from */
+  int nElem,                      /* Maximum number of values to append */
+  int iVal,                       /* Array element to populate */
+  int *pnExtract                  /* OUT: Values appended to the record */
+){
+  int rc = SQLITE_OK;
+  int nExtract = 0;
+
+  if( pExpr==0 || pExpr->op!=TK_SELECT ){
+    int i;
+    struct ValueNewStat4Ctx alloc;
+
+    alloc.pParse = pParse;
+    alloc.pIdx = pIdx;
+    alloc.ppRec = ppRec;
+
+    for(i=0; i<nElem; i++){
+      sqlite3_value *pVal = 0;
+      Expr *pElem = (pExpr ? sqlite3VectorFieldSubexpr(pExpr, i) : 0);
+      u8 aff = sqlite3IndexColumnAffinity(pParse->db, pIdx, iVal+i);
+      alloc.iVal = iVal+i;
+      rc = stat4ValueFromExpr(pParse, pElem, aff, &alloc, &pVal);
+      if( !pVal ) break;
+      nExtract++;
+    }
+  }
+
+  *pnExtract = nExtract;
+  return rc;
+}
+
+/*
+** Attempt to extract a value from expression pExpr using the methods
+** as described for sqlite3Stat4ProbeSetValue() above. 
+**
+** If successful, set *ppVal to point to a new value object and return 
+** SQLITE_OK. If no value can be extracted, but no other error occurs
+** (e.g. OOM), return SQLITE_OK and set *ppVal to NULL. Or, if an error
+** does occur, return an SQLite error code. The final value of *ppVal
+** is undefined in this case.
+*/
+SQLITE_PRIVATE int sqlite3Stat4ValueFromExpr(
+  Parse *pParse,                  /* Parse context */
+  Expr *pExpr,                    /* The expression to extract a value from */
+  u8 affinity,                    /* Affinity to use */
+  sqlite3_value **ppVal           /* OUT: New value object (or NULL) */
+){
+  return stat4ValueFromExpr(pParse, pExpr, affinity, 0, ppVal);
+}
+
+/*
+** Extract the iCol-th column from the nRec-byte record in pRec.  Write
+** the column value into *ppVal.  If *ppVal is initially NULL then a new
+** sqlite3_value object is allocated.
+**
+** If *ppVal is initially NULL then the caller is responsible for 
+** ensuring that the value written into *ppVal is eventually freed.
+*/
+SQLITE_PRIVATE int sqlite3Stat4Column(
+  sqlite3 *db,                    /* Database handle */
+  const void *pRec,               /* Pointer to buffer containing record */
+  int nRec,                       /* Size of buffer pRec in bytes */
+  int iCol,                       /* Column to extract */
+  sqlite3_value **ppVal           /* OUT: Extracted value */
+){
+  u32 t;                          /* a column type code */
+  int nHdr;                       /* Size of the header in the record */
+  int iHdr;                       /* Next unread header byte */
+  int iField;                     /* Next unread data byte */
+  int szField;                    /* Size of the current data field */
+  int i;                          /* Column index */
+  u8 *a = (u8*)pRec;              /* Typecast byte array */
+  Mem *pMem = *ppVal;             /* Write result into this Mem object */
+
+  assert( iCol>0 );
+  iHdr = getVarint32(a, nHdr);
+  if( nHdr>nRec || iHdr>=nHdr ) return SQLITE_CORRUPT_BKPT;
+  iField = nHdr;
+  for(i=0; i<=iCol; i++){
+    iHdr += getVarint32(&a[iHdr], t);
+    testcase( iHdr==nHdr );
+    testcase( iHdr==nHdr+1 );
+    if( iHdr>nHdr ) return SQLITE_CORRUPT_BKPT;
+    szField = sqlite3VdbeSerialTypeLen(t);
+    iField += szField;
+  }
+  testcase( iField==nRec );
+  testcase( iField==nRec+1 );
+  if( iField>nRec ) return SQLITE_CORRUPT_BKPT;
+  if( pMem==0 ){
+    pMem = *ppVal = sqlite3ValueNew(db);
+    if( pMem==0 ) return SQLITE_NOMEM_BKPT;
+  }
+  sqlite3VdbeSerialGet(&a[iField-szField], t, pMem);
+  pMem->enc = ENC(db);
+  return SQLITE_OK;
+}
+
+/*
+** Unless it is NULL, the argument must be an UnpackedRecord object returned
+** by an earlier call to sqlite3Stat4ProbeSetValue(). This call deletes
+** the object.
+*/
+SQLITE_PRIVATE void sqlite3Stat4ProbeFree(UnpackedRecord *pRec){
+  if( pRec ){
+    int i;
+    int nCol = pRec->pKeyInfo->nField+pRec->pKeyInfo->nXField;
+    Mem *aMem = pRec->aMem;
+    sqlite3 *db = aMem[0].db;
+    for(i=0; i<nCol; i++){
+      sqlite3VdbeMemRelease(&aMem[i]);
+    }
+    sqlite3KeyInfoUnref(pRec->pKeyInfo);
+    sqlite3DbFree(db, pRec);
+  }
+}
+#endif /* ifdef SQLITE_ENABLE_STAT4 */
+
+/*
+** Change the string value of an sqlite3_value object
+*/
+SQLITE_PRIVATE void sqlite3ValueSetStr(
+  sqlite3_value *v,     /* Value to be set */
+  int n,                /* Length of string z */
+  const void *z,        /* Text of the new string */
+  u8 enc,               /* Encoding to use */
+  void (*xDel)(void*)   /* Destructor for the string */
+){
+  if( v ) sqlite3VdbeMemSetStr((Mem *)v, z, n, enc, xDel);
+}
+
+/*
+** Free an sqlite3_value object
+*/
+SQLITE_PRIVATE void sqlite3ValueFree(sqlite3_value *v){
+  if( !v ) return;
+  sqlite3VdbeMemRelease((Mem *)v);
+  sqlite3DbFree(((Mem*)v)->db, v);
+}
+
+/*
+** The sqlite3ValueBytes() routine returns the number of bytes in the
+** sqlite3_value object assuming that it uses the encoding "enc".
+** The valueBytes() routine is a helper function.
+*/
+static SQLITE_NOINLINE int valueBytes(sqlite3_value *pVal, u8 enc){
+  return valueToText(pVal, enc)!=0 ? pVal->n : 0;
+}
+SQLITE_PRIVATE int sqlite3ValueBytes(sqlite3_value *pVal, u8 enc){
+  Mem *p = (Mem*)pVal;
+  assert( (p->flags & MEM_Null)==0 || (p->flags & (MEM_Str|MEM_Blob))==0 );
+  if( (p->flags & MEM_Str)!=0 && pVal->enc==enc ){
+    return p->n;
+  }
+  if( (p->flags & MEM_Blob)!=0 ){
+    if( p->flags & MEM_Zero ){
+      return p->n + p->u.nZero;
+    }else{
+      return p->n;
+    }
+  }
+  if( p->flags & MEM_Null ) return 0;
+  return valueBytes(pVal, enc);
+}
+
+/************** End of vdbemem.c *********************************************/
+/************** Begin file vdbeaux.c *****************************************/
+/*
+** 2003 September 6
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains code used for creating, destroying, and populating
+** a VDBE (or an "sqlite3_stmt" as it is known to the outside world.) 
+*/
+/* #include "sqliteInt.h" */
+/* #include "vdbeInt.h" */
+
+/*
+** Create a new virtual database engine.
+*/
+SQLITE_PRIVATE Vdbe *sqlite3VdbeCreate(Parse *pParse){
+  sqlite3 *db = pParse->db;
+  Vdbe *p;
+  p = sqlite3DbMallocRawNN(db, sizeof(Vdbe) );
+  if( p==0 ) return 0;
+  memset(&p->aOp, 0, sizeof(Vdbe)-offsetof(Vdbe,aOp));
+  p->db = db;
+  if( db->pVdbe ){
+    db->pVdbe->pPrev = p;
+  }
+  p->pNext = db->pVdbe;
+  p->pPrev = 0;
+  db->pVdbe = p;
+  p->magic = VDBE_MAGIC_INIT;
+  p->pParse = pParse;
+  assert( pParse->aLabel==0 );
+  assert( pParse->nLabel==0 );
+  assert( pParse->nOpAlloc==0 );
+  assert( pParse->szOpAlloc==0 );
+  return p;
+}
+
+/*
+** Change the error string stored in Vdbe.zErrMsg
+*/
+SQLITE_PRIVATE void sqlite3VdbeError(Vdbe *p, const char *zFormat, ...){
+  va_list ap;
+  sqlite3DbFree(p->db, p->zErrMsg);
+  va_start(ap, zFormat);
+  p->zErrMsg = sqlite3VMPrintf(p->db, zFormat, ap);
+  va_end(ap);
+}
+
+/*
+** Remember the SQL string for a prepared statement.
+*/
+SQLITE_PRIVATE void sqlite3VdbeSetSql(Vdbe *p, const char *z, int n, int isPrepareV2){
+  assert( isPrepareV2==1 || isPrepareV2==0 );
+  if( p==0 ) return;
+#if defined(SQLITE_OMIT_TRACE) && !defined(SQLITE_ENABLE_SQLLOG)
+  if( !isPrepareV2 ) return;
+#endif
+  assert( p->zSql==0 );
+  p->zSql = sqlite3DbStrNDup(p->db, z, n);
+  p->isPrepareV2 = (u8)isPrepareV2;
+}
+
+/*
+** Swap all content between two VDBE structures.
+*/
+SQLITE_PRIVATE void sqlite3VdbeSwap(Vdbe *pA, Vdbe *pB){
+  Vdbe tmp, *pTmp;
+  char *zTmp;
+  assert( pA->db==pB->db );
+  tmp = *pA;
+  *pA = *pB;
+  *pB = tmp;
+  pTmp = pA->pNext;
+  pA->pNext = pB->pNext;
+  pB->pNext = pTmp;
+  pTmp = pA->pPrev;
+  pA->pPrev = pB->pPrev;
+  pB->pPrev = pTmp;
+  zTmp = pA->zSql;
+  pA->zSql = pB->zSql;
+  pB->zSql = zTmp;
+  pB->isPrepareV2 = pA->isPrepareV2;
+}
+
+/*
+** Resize the Vdbe.aOp array so that it is at least nOp elements larger 
+** than its current size. nOp is guaranteed to be less than or equal
+** to 1024/sizeof(Op).
+**
+** If an out-of-memory error occurs while resizing the array, return
+** SQLITE_NOMEM. In this case Vdbe.aOp and Parse.nOpAlloc remain 
+** unchanged (this is so that any opcodes already allocated can be 
+** correctly deallocated along with the rest of the Vdbe).
+*/
+static int growOpArray(Vdbe *v, int nOp){
+  VdbeOp *pNew;
+  Parse *p = v->pParse;
+
+  /* The SQLITE_TEST_REALLOC_STRESS compile-time option is designed to force
+  ** more frequent reallocs and hence provide more opportunities for 
+  ** simulated OOM faults.  SQLITE_TEST_REALLOC_STRESS is generally used
+  ** during testing only.  With SQLITE_TEST_REALLOC_STRESS grow the op array
+  ** by the minimum* amount required until the size reaches 512.  Normal
+  ** operation (without SQLITE_TEST_REALLOC_STRESS) is to double the current
+  ** size of the op array or add 1KB of space, whichever is smaller. */
+#ifdef SQLITE_TEST_REALLOC_STRESS
+  int nNew = (p->nOpAlloc>=512 ? p->nOpAlloc*2 : p->nOpAlloc+nOp);
+#else
+  int nNew = (p->nOpAlloc ? p->nOpAlloc*2 : (int)(1024/sizeof(Op)));
+  UNUSED_PARAMETER(nOp);
+#endif
+
+  assert( nOp<=(1024/sizeof(Op)) );
+  assert( nNew>=(p->nOpAlloc+nOp) );
+  pNew = sqlite3DbRealloc(p->db, v->aOp, nNew*sizeof(Op));
+  if( pNew ){
+    p->szOpAlloc = sqlite3DbMallocSize(p->db, pNew);
+    p->nOpAlloc = p->szOpAlloc/sizeof(Op);
+    v->aOp = pNew;
+  }
+  return (pNew ? SQLITE_OK : SQLITE_NOMEM_BKPT);
+}
+
+#ifdef SQLITE_DEBUG
+/* This routine is just a convenient place to set a breakpoint that will
+** fire after each opcode is inserted and displayed using
+** "PRAGMA vdbe_addoptrace=on".
+*/
+static void test_addop_breakpoint(void){
+  static int n = 0;
+  n++;
+}
+#endif
+
+/*
+** Add a new instruction to the list of instructions current in the
+** VDBE.  Return the address of the new instruction.
+**
+** Parameters:
+**
+**    p               Pointer to the VDBE
+**
+**    op              The opcode for this instruction
+**
+**    p1, p2, p3      Operands
+**
+** Use the sqlite3VdbeResolveLabel() function to fix an address and
+** the sqlite3VdbeChangeP4() function to change the value of the P4
+** operand.
+*/
+static SQLITE_NOINLINE int growOp3(Vdbe *p, int op, int p1, int p2, int p3){
+  assert( p->pParse->nOpAlloc<=p->nOp );
+  if( growOpArray(p, 1) ) return 1;
+  assert( p->pParse->nOpAlloc>p->nOp );
+  return sqlite3VdbeAddOp3(p, op, p1, p2, p3);
+}
+SQLITE_PRIVATE int sqlite3VdbeAddOp3(Vdbe *p, int op, int p1, int p2, int p3){
+  int i;
+  VdbeOp *pOp;
+
+  i = p->nOp;
+  assert( p->magic==VDBE_MAGIC_INIT );
+  assert( op>=0 && op<0xff );
+  if( p->pParse->nOpAlloc<=i ){
+    return growOp3(p, op, p1, p2, p3);
+  }
+  p->nOp++;
+  pOp = &p->aOp[i];
+  pOp->opcode = (u8)op;
+  pOp->p5 = 0;
+  pOp->p1 = p1;
+  pOp->p2 = p2;
+  pOp->p3 = p3;
+  pOp->p4.p = 0;
+  pOp->p4type = P4_NOTUSED;
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+  pOp->zComment = 0;
+#endif
+#ifdef SQLITE_DEBUG
+  if( p->db->flags & SQLITE_VdbeAddopTrace ){
+    int jj, kk;
+    Parse *pParse = p->pParse;
+    for(jj=kk=0; jj<pParse->nColCache; jj++){
+      struct yColCache *x = pParse->aColCache + jj;
+      printf(" r[%d]={%d:%d}", x->iReg, x->iTable, x->iColumn);
+      kk++;
+    }
+    if( kk ) printf("\n");
+    sqlite3VdbePrintOp(0, i, &p->aOp[i]);
+    test_addop_breakpoint();
+  }
+#endif
+#ifdef VDBE_PROFILE
+  pOp->cycles = 0;
+  pOp->cnt = 0;
+#endif
+#ifdef SQLITE_VDBE_COVERAGE
+  pOp->iSrcLine = 0;
+#endif
+  return i;
+}
+SQLITE_PRIVATE int sqlite3VdbeAddOp0(Vdbe *p, int op){
+  return sqlite3VdbeAddOp3(p, op, 0, 0, 0);
+}
+SQLITE_PRIVATE int sqlite3VdbeAddOp1(Vdbe *p, int op, int p1){
+  return sqlite3VdbeAddOp3(p, op, p1, 0, 0);
+}
+SQLITE_PRIVATE int sqlite3VdbeAddOp2(Vdbe *p, int op, int p1, int p2){
+  return sqlite3VdbeAddOp3(p, op, p1, p2, 0);
+}
+
+/* Generate code for an unconditional jump to instruction iDest
+*/
+SQLITE_PRIVATE int sqlite3VdbeGoto(Vdbe *p, int iDest){
+  return sqlite3VdbeAddOp3(p, OP_Goto, 0, iDest, 0);
+}
+
+/* Generate code to cause the string zStr to be loaded into
+** register iDest
+*/
+SQLITE_PRIVATE int sqlite3VdbeLoadString(Vdbe *p, int iDest, const char *zStr){
+  return sqlite3VdbeAddOp4(p, OP_String8, 0, iDest, 0, zStr, 0);
+}
+
+/*
+** Generate code that initializes multiple registers to string or integer
+** constants.  The registers begin with iDest and increase consecutively.
+** One register is initialized for each characgter in zTypes[].  For each
+** "s" character in zTypes[], the register is a string if the argument is
+** not NULL, or OP_Null if the value is a null pointer.  For each "i" character
+** in zTypes[], the register is initialized to an integer.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMultiLoad(Vdbe *p, int iDest, const char *zTypes, ...){
+  va_list ap;
+  int i;
+  char c;
+  va_start(ap, zTypes);
+  for(i=0; (c = zTypes[i])!=0; i++){
+    if( c=='s' ){
+      const char *z = va_arg(ap, const char*);
+      sqlite3VdbeAddOp4(p, z==0 ? OP_Null : OP_String8, 0, iDest++, 0, z, 0);
+    }else{
+      assert( c=='i' );
+      sqlite3VdbeAddOp2(p, OP_Integer, va_arg(ap, int), iDest++);
+    }
+  }
+  va_end(ap);
+}
+
+/*
+** Add an opcode that includes the p4 value as a pointer.
+*/
+SQLITE_PRIVATE int sqlite3VdbeAddOp4(
+  Vdbe *p,            /* Add the opcode to this VM */
+  int op,             /* The new opcode */
+  int p1,             /* The P1 operand */
+  int p2,             /* The P2 operand */
+  int p3,             /* The P3 operand */
+  const char *zP4,    /* The P4 operand */
+  int p4type          /* P4 operand type */
+){
+  int addr = sqlite3VdbeAddOp3(p, op, p1, p2, p3);
+  sqlite3VdbeChangeP4(p, addr, zP4, p4type);
+  return addr;
+}
+
+/*
+** Add an opcode that includes the p4 value with a P4_INT64 or
+** P4_REAL type.
+*/
+SQLITE_PRIVATE int sqlite3VdbeAddOp4Dup8(
+  Vdbe *p,            /* Add the opcode to this VM */
+  int op,             /* The new opcode */
+  int p1,             /* The P1 operand */
+  int p2,             /* The P2 operand */
+  int p3,             /* The P3 operand */
+  const u8 *zP4,      /* The P4 operand */
+  int p4type          /* P4 operand type */
+){
+  char *p4copy = sqlite3DbMallocRawNN(sqlite3VdbeDb(p), 8);
+  if( p4copy ) memcpy(p4copy, zP4, 8);
+  return sqlite3VdbeAddOp4(p, op, p1, p2, p3, p4copy, p4type);
+}
+
+/*
+** Add an OP_ParseSchema opcode.  This routine is broken out from
+** sqlite3VdbeAddOp4() since it needs to also needs to mark all btrees
+** as having been used.
+**
+** The zWhere string must have been obtained from sqlite3_malloc().
+** This routine will take ownership of the allocated memory.
+*/
+SQLITE_PRIVATE void sqlite3VdbeAddParseSchemaOp(Vdbe *p, int iDb, char *zWhere){
+  int j;
+  sqlite3VdbeAddOp4(p, OP_ParseSchema, iDb, 0, 0, zWhere, P4_DYNAMIC);
+  for(j=0; j<p->db->nDb; j++) sqlite3VdbeUsesBtree(p, j);
+}
+
+/*
+** Add an opcode that includes the p4 value as an integer.
+*/
+SQLITE_PRIVATE int sqlite3VdbeAddOp4Int(
+  Vdbe *p,            /* Add the opcode to this VM */
+  int op,             /* The new opcode */
+  int p1,             /* The P1 operand */
+  int p2,             /* The P2 operand */
+  int p3,             /* The P3 operand */
+  int p4              /* The P4 operand as an integer */
+){
+  int addr = sqlite3VdbeAddOp3(p, op, p1, p2, p3);
+  sqlite3VdbeChangeP4(p, addr, SQLITE_INT_TO_PTR(p4), P4_INT32);
+  return addr;
+}
+
+/* Insert the end of a co-routine
+*/
+SQLITE_PRIVATE void sqlite3VdbeEndCoroutine(Vdbe *v, int regYield){
+  sqlite3VdbeAddOp1(v, OP_EndCoroutine, regYield);
+
+  /* Clear the temporary register cache, thereby ensuring that each
+  ** co-routine has its own independent set of registers, because co-routines
+  ** might expect their registers to be preserved across an OP_Yield, and
+  ** that could cause problems if two or more co-routines are using the same
+  ** temporary register.
+  */
+  v->pParse->nTempReg = 0;
+  v->pParse->nRangeReg = 0;
+}
+
+/*
+** Create a new symbolic label for an instruction that has yet to be
+** coded.  The symbolic label is really just a negative number.  The
+** label can be used as the P2 value of an operation.  Later, when
+** the label is resolved to a specific address, the VDBE will scan
+** through its operation list and change all values of P2 which match
+** the label into the resolved address.
+**
+** The VDBE knows that a P2 value is a label because labels are
+** always negative and P2 values are suppose to be non-negative.
+** Hence, a negative P2 value is a label that has yet to be resolved.
+**
+** Zero is returned if a malloc() fails.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMakeLabel(Vdbe *v){
+  Parse *p = v->pParse;
+  int i = p->nLabel++;
+  assert( v->magic==VDBE_MAGIC_INIT );
+  if( (i & (i-1))==0 ){
+    p->aLabel = sqlite3DbReallocOrFree(p->db, p->aLabel, 
+                                       (i*2+1)*sizeof(p->aLabel[0]));
+  }
+  if( p->aLabel ){
+    p->aLabel[i] = -1;
+  }
+  return ADDR(i);
+}
+
+/*
+** Resolve label "x" to be the address of the next instruction to
+** be inserted.  The parameter "x" must have been obtained from
+** a prior call to sqlite3VdbeMakeLabel().
+*/
+SQLITE_PRIVATE void sqlite3VdbeResolveLabel(Vdbe *v, int x){
+  Parse *p = v->pParse;
+  int j = ADDR(x);
+  assert( v->magic==VDBE_MAGIC_INIT );
+  assert( j<p->nLabel );
+  assert( j>=0 );
+  if( p->aLabel ){
+    p->aLabel[j] = v->nOp;
+  }
+}
+
+/*
+** Mark the VDBE as one that can only be run one time.
+*/
+SQLITE_PRIVATE void sqlite3VdbeRunOnlyOnce(Vdbe *p){
+  p->runOnlyOnce = 1;
+}
+
+/*
+** Mark the VDBE as one that can only be run multiple times.
+*/
+SQLITE_PRIVATE void sqlite3VdbeReusable(Vdbe *p){
+  p->runOnlyOnce = 0;
+}
+
+#ifdef SQLITE_DEBUG /* sqlite3AssertMayAbort() logic */
+
+/*
+** The following type and function are used to iterate through all opcodes
+** in a Vdbe main program and each of the sub-programs (triggers) it may 
+** invoke directly or indirectly. It should be used as follows:
+**
+**   Op *pOp;
+**   VdbeOpIter sIter;
+**
+**   memset(&sIter, 0, sizeof(sIter));
+**   sIter.v = v;                            // v is of type Vdbe* 
+**   while( (pOp = opIterNext(&sIter)) ){
+**     // Do something with pOp
+**   }
+**   sqlite3DbFree(v->db, sIter.apSub);
+** 
+*/
+typedef struct VdbeOpIter VdbeOpIter;
+struct VdbeOpIter {
+  Vdbe *v;                   /* Vdbe to iterate through the opcodes of */
+  SubProgram **apSub;        /* Array of subprograms */
+  int nSub;                  /* Number of entries in apSub */
+  int iAddr;                 /* Address of next instruction to return */
+  int iSub;                  /* 0 = main program, 1 = first sub-program etc. */
+};
+static Op *opIterNext(VdbeOpIter *p){
+  Vdbe *v = p->v;
+  Op *pRet = 0;
+  Op *aOp;
+  int nOp;
+
+  if( p->iSub<=p->nSub ){
+
+    if( p->iSub==0 ){
+      aOp = v->aOp;
+      nOp = v->nOp;
+    }else{
+      aOp = p->apSub[p->iSub-1]->aOp;
+      nOp = p->apSub[p->iSub-1]->nOp;
+    }
+    assert( p->iAddr<nOp );
+
+    pRet = &aOp[p->iAddr];
+    p->iAddr++;
+    if( p->iAddr==nOp ){
+      p->iSub++;
+      p->iAddr = 0;
+    }
+  
+    if( pRet->p4type==P4_SUBPROGRAM ){
+      int nByte = (p->nSub+1)*sizeof(SubProgram*);
+      int j;
+      for(j=0; j<p->nSub; j++){
+        if( p->apSub[j]==pRet->p4.pProgram ) break;
+      }
+      if( j==p->nSub ){
+        p->apSub = sqlite3DbReallocOrFree(v->db, p->apSub, nByte);
+        if( !p->apSub ){
+          pRet = 0;
+        }else{
+          p->apSub[p->nSub++] = pRet->p4.pProgram;
+        }
+      }
+    }
+  }
+
+  return pRet;
+}
+
+/*
+** Check if the program stored in the VM associated with pParse may
+** throw an ABORT exception (causing the statement, but not entire transaction
+** to be rolled back). This condition is true if the main program or any
+** sub-programs contains any of the following:
+**
+**   *  OP_Halt with P1=SQLITE_CONSTRAINT and P2=OE_Abort.
+**   *  OP_HaltIfNull with P1=SQLITE_CONSTRAINT and P2=OE_Abort.
+**   *  OP_Destroy
+**   *  OP_VUpdate
+**   *  OP_VRename
+**   *  OP_FkCounter with P2==0 (immediate foreign key constraint)
+**   *  OP_CreateTable and OP_InitCoroutine (for CREATE TABLE AS SELECT ...)
+**
+** Then check that the value of Parse.mayAbort is true if an
+** ABORT may be thrown, or false otherwise. Return true if it does
+** match, or false otherwise. This function is intended to be used as
+** part of an assert statement in the compiler. Similar to:
+**
+**   assert( sqlite3VdbeAssertMayAbort(pParse->pVdbe, pParse->mayAbort) );
+*/
+SQLITE_PRIVATE int sqlite3VdbeAssertMayAbort(Vdbe *v, int mayAbort){
+  int hasAbort = 0;
+  int hasFkCounter = 0;
+  int hasCreateTable = 0;
+  int hasInitCoroutine = 0;
+  Op *pOp;
+  VdbeOpIter sIter;
+  memset(&sIter, 0, sizeof(sIter));
+  sIter.v = v;
+
+  while( (pOp = opIterNext(&sIter))!=0 ){
+    int opcode = pOp->opcode;
+    if( opcode==OP_Destroy || opcode==OP_VUpdate || opcode==OP_VRename 
+     || ((opcode==OP_Halt || opcode==OP_HaltIfNull) 
+      && ((pOp->p1&0xff)==SQLITE_CONSTRAINT && pOp->p2==OE_Abort))
+    ){
+      hasAbort = 1;
+      break;
+    }
+    if( opcode==OP_CreateTable ) hasCreateTable = 1;
+    if( opcode==OP_InitCoroutine ) hasInitCoroutine = 1;
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+    if( opcode==OP_FkCounter && pOp->p1==0 && pOp->p2==1 ){
+      hasFkCounter = 1;
+    }
+#endif
+  }
+  sqlite3DbFree(v->db, sIter.apSub);
+
+  /* Return true if hasAbort==mayAbort. Or if a malloc failure occurred.
+  ** If malloc failed, then the while() loop above may not have iterated
+  ** through all opcodes and hasAbort may be set incorrectly. Return
+  ** true for this case to prevent the assert() in the callers frame
+  ** from failing.  */
+  return ( v->db->mallocFailed || hasAbort==mayAbort || hasFkCounter
+              || (hasCreateTable && hasInitCoroutine) );
+}
+#endif /* SQLITE_DEBUG - the sqlite3AssertMayAbort() function */
+
+/*
+** This routine is called after all opcodes have been inserted.  It loops
+** through all the opcodes and fixes up some details.
+**
+** (1) For each jump instruction with a negative P2 value (a label)
+**     resolve the P2 value to an actual address.
+**
+** (2) Compute the maximum number of arguments used by any SQL function
+**     and store that value in *pMaxFuncArgs.
+**
+** (3) Update the Vdbe.readOnly and Vdbe.bIsReader flags to accurately
+**     indicate what the prepared statement actually does.
+**
+** (4) Initialize the p4.xAdvance pointer on opcodes that use it.
+**
+** (5) Reclaim the memory allocated for storing labels.
+**
+** This routine will only function correctly if the mkopcodeh.tcl generator
+** script numbers the opcodes correctly.  Changes to this routine must be
+** coordinated with changes to mkopcodeh.tcl.
+*/
+static void resolveP2Values(Vdbe *p, int *pMaxFuncArgs){
+  int nMaxArgs = *pMaxFuncArgs;
+  Op *pOp;
+  Parse *pParse = p->pParse;
+  int *aLabel = pParse->aLabel;
+  p->readOnly = 1;
+  p->bIsReader = 0;
+  pOp = &p->aOp[p->nOp-1];
+  while(1){
+
+    /* Only JUMP opcodes and the short list of special opcodes in the switch
+    ** below need to be considered.  The mkopcodeh.tcl generator script groups
+    ** all these opcodes together near the front of the opcode list.  Skip
+    ** any opcode that does not need processing by virtual of the fact that
+    ** it is larger than SQLITE_MX_JUMP_OPCODE, as a performance optimization.
+    */
+    if( pOp->opcode<=SQLITE_MX_JUMP_OPCODE ){
+      /* NOTE: Be sure to update mkopcodeh.tcl when adding or removing
+      ** cases from this switch! */
+      switch( pOp->opcode ){
+        case OP_Transaction: {
+          if( pOp->p2!=0 ) p->readOnly = 0;
+          /* fall thru */
+        }
+        case OP_AutoCommit:
+        case OP_Savepoint: {
+          p->bIsReader = 1;
+          break;
+        }
+#ifndef SQLITE_OMIT_WAL
+        case OP_Checkpoint:
+#endif
+        case OP_Vacuum:
+        case OP_JournalMode: {
+          p->readOnly = 0;
+          p->bIsReader = 1;
+          break;
+        }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+        case OP_VUpdate: {
+          if( pOp->p2>nMaxArgs ) nMaxArgs = pOp->p2;
+          break;
+        }
+        case OP_VFilter: {
+          int n;
+          assert( (pOp - p->aOp) >= 3 );
+          assert( pOp[-1].opcode==OP_Integer );
+          n = pOp[-1].p1;
+          if( n>nMaxArgs ) nMaxArgs = n;
+          break;
+        }
+#endif
+        case OP_Next:
+        case OP_NextIfOpen:
+        case OP_SorterNext: {
+          pOp->p4.xAdvance = sqlite3BtreeNext;
+          pOp->p4type = P4_ADVANCE;
+          break;
+        }
+        case OP_Prev:
+        case OP_PrevIfOpen: {
+          pOp->p4.xAdvance = sqlite3BtreePrevious;
+          pOp->p4type = P4_ADVANCE;
+          break;
+        }
+      }
+      if( (sqlite3OpcodeProperty[pOp->opcode] & OPFLG_JUMP)!=0 && pOp->p2<0 ){
+        assert( ADDR(pOp->p2)<pParse->nLabel );
+        pOp->p2 = aLabel[ADDR(pOp->p2)];
+      }
+    }
+    if( pOp==p->aOp ) break;
+    pOp--;
+  }
+  sqlite3DbFree(p->db, pParse->aLabel);
+  pParse->aLabel = 0;
+  pParse->nLabel = 0;
+  *pMaxFuncArgs = nMaxArgs;
+  assert( p->bIsReader!=0 || DbMaskAllZero(p->btreeMask) );
+}
+
+/*
+** Return the address of the next instruction to be inserted.
+*/
+SQLITE_PRIVATE int sqlite3VdbeCurrentAddr(Vdbe *p){
+  assert( p->magic==VDBE_MAGIC_INIT );
+  return p->nOp;
+}
+
+/*
+** Verify that at least N opcode slots are available in p without
+** having to malloc for more space (except when compiled using
+** SQLITE_TEST_REALLOC_STRESS).  This interface is used during testing
+** to verify that certain calls to sqlite3VdbeAddOpList() can never
+** fail due to a OOM fault and hence that the return value from
+** sqlite3VdbeAddOpList() will always be non-NULL.
+*/
+#if defined(SQLITE_DEBUG) && !defined(SQLITE_TEST_REALLOC_STRESS)
+SQLITE_PRIVATE void sqlite3VdbeVerifyNoMallocRequired(Vdbe *p, int N){
+  assert( p->nOp + N <= p->pParse->nOpAlloc );
+}
+#endif
+
+/*
+** This function returns a pointer to the array of opcodes associated with
+** the Vdbe passed as the first argument. It is the callers responsibility
+** to arrange for the returned array to be eventually freed using the 
+** vdbeFreeOpArray() function.
+**
+** Before returning, *pnOp is set to the number of entries in the returned
+** array. Also, *pnMaxArg is set to the larger of its current value and 
+** the number of entries in the Vdbe.apArg[] array required to execute the 
+** returned program.
+*/
+SQLITE_PRIVATE VdbeOp *sqlite3VdbeTakeOpArray(Vdbe *p, int *pnOp, int *pnMaxArg){
+  VdbeOp *aOp = p->aOp;
+  assert( aOp && !p->db->mallocFailed );
+
+  /* Check that sqlite3VdbeUsesBtree() was not called on this VM */
+  assert( DbMaskAllZero(p->btreeMask) );
+
+  resolveP2Values(p, pnMaxArg);
+  *pnOp = p->nOp;
+  p->aOp = 0;
+  return aOp;
+}
+
+/*
+** Add a whole list of operations to the operation stack.  Return a
+** pointer to the first operation inserted.
+**
+** Non-zero P2 arguments to jump instructions are automatically adjusted
+** so that the jump target is relative to the first operation inserted.
+*/
+SQLITE_PRIVATE VdbeOp *sqlite3VdbeAddOpList(
+  Vdbe *p,                     /* Add opcodes to the prepared statement */
+  int nOp,                     /* Number of opcodes to add */
+  VdbeOpList const *aOp,       /* The opcodes to be added */
+  int iLineno                  /* Source-file line number of first opcode */
+){
+  int i;
+  VdbeOp *pOut, *pFirst;
+  assert( nOp>0 );
+  assert( p->magic==VDBE_MAGIC_INIT );
+  if( p->nOp + nOp > p->pParse->nOpAlloc && growOpArray(p, nOp) ){
+    return 0;
+  }
+  pFirst = pOut = &p->aOp[p->nOp];
+  for(i=0; i<nOp; i++, aOp++, pOut++){
+    pOut->opcode = aOp->opcode;
+    pOut->p1 = aOp->p1;
+    pOut->p2 = aOp->p2;
+    assert( aOp->p2>=0 );
+    if( (sqlite3OpcodeProperty[aOp->opcode] & OPFLG_JUMP)!=0 && aOp->p2>0 ){
+      pOut->p2 += p->nOp;
+    }
+    pOut->p3 = aOp->p3;
+    pOut->p4type = P4_NOTUSED;
+    pOut->p4.p = 0;
+    pOut->p5 = 0;
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+    pOut->zComment = 0;
+#endif
+#ifdef SQLITE_VDBE_COVERAGE
+    pOut->iSrcLine = iLineno+i;
+#else
+    (void)iLineno;
+#endif
+#ifdef SQLITE_DEBUG
+    if( p->db->flags & SQLITE_VdbeAddopTrace ){
+      sqlite3VdbePrintOp(0, i+p->nOp, &p->aOp[i+p->nOp]);
+    }
+#endif
+  }
+  p->nOp += nOp;
+  return pFirst;
+}
+
+#if defined(SQLITE_ENABLE_STMT_SCANSTATUS)
+/*
+** Add an entry to the array of counters managed by sqlite3_stmt_scanstatus().
+*/
+SQLITE_PRIVATE void sqlite3VdbeScanStatus(
+  Vdbe *p,                        /* VM to add scanstatus() to */
+  int addrExplain,                /* Address of OP_Explain (or 0) */
+  int addrLoop,                   /* Address of loop counter */ 
+  int addrVisit,                  /* Address of rows visited counter */
+  LogEst nEst,                    /* Estimated number of output rows */
+  const char *zName               /* Name of table or index being scanned */
+){
+  int nByte = (p->nScan+1) * sizeof(ScanStatus);
+  ScanStatus *aNew;
+  aNew = (ScanStatus*)sqlite3DbRealloc(p->db, p->aScan, nByte);
+  if( aNew ){
+    ScanStatus *pNew = &aNew[p->nScan++];
+    pNew->addrExplain = addrExplain;
+    pNew->addrLoop = addrLoop;
+    pNew->addrVisit = addrVisit;
+    pNew->nEst = nEst;
+    pNew->zName = sqlite3DbStrDup(p->db, zName);
+    p->aScan = aNew;
+  }
+}
+#endif
+
+
+/*
+** Change the value of the opcode, or P1, P2, P3, or P5 operands
+** for a specific instruction.
+*/
+SQLITE_PRIVATE void sqlite3VdbeChangeOpcode(Vdbe *p, u32 addr, u8 iNewOpcode){
+  sqlite3VdbeGetOp(p,addr)->opcode = iNewOpcode;
+}
+SQLITE_PRIVATE void sqlite3VdbeChangeP1(Vdbe *p, u32 addr, int val){
+  sqlite3VdbeGetOp(p,addr)->p1 = val;
+}
+SQLITE_PRIVATE void sqlite3VdbeChangeP2(Vdbe *p, u32 addr, int val){
+  sqlite3VdbeGetOp(p,addr)->p2 = val;
+}
+SQLITE_PRIVATE void sqlite3VdbeChangeP3(Vdbe *p, u32 addr, int val){
+  sqlite3VdbeGetOp(p,addr)->p3 = val;
+}
+SQLITE_PRIVATE void sqlite3VdbeChangeP5(Vdbe *p, u8 p5){
+  assert( p->nOp>0 || p->db->mallocFailed );
+  if( p->nOp>0 ) p->aOp[p->nOp-1].p5 = p5;
+}
+
+/*
+** Change the P2 operand of instruction addr so that it points to
+** the address of the next instruction to be coded.
+*/
+SQLITE_PRIVATE void sqlite3VdbeJumpHere(Vdbe *p, int addr){
+  sqlite3VdbeChangeP2(p, addr, p->nOp);
+}
+
+
+/*
+** If the input FuncDef structure is ephemeral, then free it.  If
+** the FuncDef is not ephermal, then do nothing.
+*/
+static void freeEphemeralFunction(sqlite3 *db, FuncDef *pDef){
+  if( (pDef->funcFlags & SQLITE_FUNC_EPHEM)!=0 ){
+    sqlite3DbFree(db, pDef);
+  }
+}
+
+static void vdbeFreeOpArray(sqlite3 *, Op *, int);
+
+/*
+** Delete a P4 value if necessary.
+*/
+static SQLITE_NOINLINE void freeP4Mem(sqlite3 *db, Mem *p){
+  if( p->szMalloc ) sqlite3DbFree(db, p->zMalloc);
+  sqlite3DbFree(db, p);
+}
+static SQLITE_NOINLINE void freeP4FuncCtx(sqlite3 *db, sqlite3_context *p){
+  freeEphemeralFunction(db, p->pFunc);
+  sqlite3DbFree(db, p);
+}
+static void freeP4(sqlite3 *db, int p4type, void *p4){
+  assert( db );
+  switch( p4type ){
+    case P4_FUNCCTX: {
+      freeP4FuncCtx(db, (sqlite3_context*)p4);
+      break;
+    }
+    case P4_REAL:
+    case P4_INT64:
+    case P4_DYNAMIC:
+    case P4_INTARRAY: {
+      sqlite3DbFree(db, p4);
+      break;
+    }
+    case P4_KEYINFO: {
+      if( db->pnBytesFreed==0 ) sqlite3KeyInfoUnref((KeyInfo*)p4);
+      break;
+    }
+#ifdef SQLITE_ENABLE_CURSOR_HINTS
+    case P4_EXPR: {
+      sqlite3ExprDelete(db, (Expr*)p4);
+      break;
+    }
+#endif
+    case P4_MPRINTF: {
+      if( db->pnBytesFreed==0 ) sqlite3_free(p4);
+      break;
+    }
+    case P4_FUNCDEF: {
+      freeEphemeralFunction(db, (FuncDef*)p4);
+      break;
+    }
+    case P4_MEM: {
+      if( db->pnBytesFreed==0 ){
+        sqlite3ValueFree((sqlite3_value*)p4);
+      }else{
+        freeP4Mem(db, (Mem*)p4);
+      }
+      break;
+    }
+    case P4_VTAB : {
+      if( db->pnBytesFreed==0 ) sqlite3VtabUnlock((VTable *)p4);
+      break;
+    }
+  }
+}
+
+/*
+** Free the space allocated for aOp and any p4 values allocated for the
+** opcodes contained within. If aOp is not NULL it is assumed to contain 
+** nOp entries. 
+*/
+static void vdbeFreeOpArray(sqlite3 *db, Op *aOp, int nOp){
+  if( aOp ){
+    Op *pOp;
+    for(pOp=aOp; pOp<&aOp[nOp]; pOp++){
+      if( pOp->p4type ) freeP4(db, pOp->p4type, pOp->p4.p);
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+      sqlite3DbFree(db, pOp->zComment);
+#endif     
+    }
+  }
+  sqlite3DbFree(db, aOp);
+}
+
+/*
+** Link the SubProgram object passed as the second argument into the linked
+** list at Vdbe.pSubProgram. This list is used to delete all sub-program
+** objects when the VM is no longer required.
+*/
+SQLITE_PRIVATE void sqlite3VdbeLinkSubProgram(Vdbe *pVdbe, SubProgram *p){
+  p->pNext = pVdbe->pProgram;
+  pVdbe->pProgram = p;
+}
+
+/*
+** Change the opcode at addr into OP_Noop
+*/
+SQLITE_PRIVATE int sqlite3VdbeChangeToNoop(Vdbe *p, int addr){
+  VdbeOp *pOp;
+  if( p->db->mallocFailed ) return 0;
+  assert( addr>=0 && addr<p->nOp );
+  pOp = &p->aOp[addr];
+  freeP4(p->db, pOp->p4type, pOp->p4.p);
+  pOp->p4type = P4_NOTUSED;
+  pOp->p4.z = 0;
+  pOp->opcode = OP_Noop;
+  return 1;
+}
+
+/*
+** If the last opcode is "op" and it is not a jump destination,
+** then remove it.  Return true if and only if an opcode was removed.
+*/
+SQLITE_PRIVATE int sqlite3VdbeDeletePriorOpcode(Vdbe *p, u8 op){
+  if( p->nOp>0 && p->aOp[p->nOp-1].opcode==op ){
+    return sqlite3VdbeChangeToNoop(p, p->nOp-1);
+  }else{
+    return 0;
+  }
+}
+
+/*
+** Change the value of the P4 operand for a specific instruction.
+** This routine is useful when a large program is loaded from a
+** static array using sqlite3VdbeAddOpList but we want to make a
+** few minor changes to the program.
+**
+** If n>=0 then the P4 operand is dynamic, meaning that a copy of
+** the string is made into memory obtained from sqlite3_malloc().
+** A value of n==0 means copy bytes of zP4 up to and including the
+** first null byte.  If n>0 then copy n+1 bytes of zP4.
+** 
+** Other values of n (P4_STATIC, P4_COLLSEQ etc.) indicate that zP4 points
+** to a string or structure that is guaranteed to exist for the lifetime of
+** the Vdbe. In these cases we can just copy the pointer.
+**
+** If addr<0 then change P4 on the most recently inserted instruction.
+*/
+static void SQLITE_NOINLINE vdbeChangeP4Full(
+  Vdbe *p,
+  Op *pOp,
+  const char *zP4,
+  int n
+){
+  if( pOp->p4type ){
+    freeP4(p->db, pOp->p4type, pOp->p4.p);
+    pOp->p4type = 0;
+    pOp->p4.p = 0;
+  }
+  if( n<0 ){
+    sqlite3VdbeChangeP4(p, (int)(pOp - p->aOp), zP4, n);
+  }else{
+    if( n==0 ) n = sqlite3Strlen30(zP4);
+    pOp->p4.z = sqlite3DbStrNDup(p->db, zP4, n);
+    pOp->p4type = P4_DYNAMIC;
+  }
+}
+SQLITE_PRIVATE void sqlite3VdbeChangeP4(Vdbe *p, int addr, const char *zP4, int n){
+  Op *pOp;
+  sqlite3 *db;
+  assert( p!=0 );
+  db = p->db;
+  assert( p->magic==VDBE_MAGIC_INIT );
+  assert( p->aOp!=0 || db->mallocFailed );
+  if( db->mallocFailed ){
+    if( n!=P4_VTAB ) freeP4(db, n, (void*)*(char**)&zP4);
+    return;
+  }
+  assert( p->nOp>0 );
+  assert( addr<p->nOp );
+  if( addr<0 ){
+    addr = p->nOp - 1;
+  }
+  pOp = &p->aOp[addr];
+  if( n>=0 || pOp->p4type ){
+    vdbeChangeP4Full(p, pOp, zP4, n);
+    return;
+  }
+  if( n==P4_INT32 ){
+    /* Note: this cast is safe, because the origin data point was an int
+    ** that was cast to a (const char *). */
+    pOp->p4.i = SQLITE_PTR_TO_INT(zP4);
+    pOp->p4type = P4_INT32;
+  }else if( zP4!=0 ){
+    assert( n<0 );
+    pOp->p4.p = (void*)zP4;
+    pOp->p4type = (signed char)n;
+    if( n==P4_VTAB ) sqlite3VtabLock((VTable*)zP4);
+  }
+}
+
+/*
+** Set the P4 on the most recently added opcode to the KeyInfo for the
+** index given.
+*/
+SQLITE_PRIVATE void sqlite3VdbeSetP4KeyInfo(Parse *pParse, Index *pIdx){
+  Vdbe *v = pParse->pVdbe;
+  assert( v!=0 );
+  assert( pIdx!=0 );
+  sqlite3VdbeChangeP4(v, -1, (char*)sqlite3KeyInfoOfIndex(pParse, pIdx),
+                      P4_KEYINFO);
+}
+
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+/*
+** Change the comment on the most recently coded instruction.  Or
+** insert a No-op and add the comment to that new instruction.  This
+** makes the code easier to read during debugging.  None of this happens
+** in a production build.
+*/
+static void vdbeVComment(Vdbe *p, const char *zFormat, va_list ap){
+  assert( p->nOp>0 || p->aOp==0 );
+  assert( p->aOp==0 || p->aOp[p->nOp-1].zComment==0 || p->db->mallocFailed );
+  if( p->nOp ){
+    assert( p->aOp );
+    sqlite3DbFree(p->db, p->aOp[p->nOp-1].zComment);
+    p->aOp[p->nOp-1].zComment = sqlite3VMPrintf(p->db, zFormat, ap);
+  }
+}
+SQLITE_PRIVATE void sqlite3VdbeComment(Vdbe *p, const char *zFormat, ...){
+  va_list ap;
+  if( p ){
+    va_start(ap, zFormat);
+    vdbeVComment(p, zFormat, ap);
+    va_end(ap);
+  }
+}
+SQLITE_PRIVATE void sqlite3VdbeNoopComment(Vdbe *p, const char *zFormat, ...){
+  va_list ap;
+  if( p ){
+    sqlite3VdbeAddOp0(p, OP_Noop);
+    va_start(ap, zFormat);
+    vdbeVComment(p, zFormat, ap);
+    va_end(ap);
+  }
+}
+#endif  /* NDEBUG */
+
+#ifdef SQLITE_VDBE_COVERAGE
+/*
+** Set the value if the iSrcLine field for the previously coded instruction.
+*/
+SQLITE_PRIVATE void sqlite3VdbeSetLineNumber(Vdbe *v, int iLine){
+  sqlite3VdbeGetOp(v,-1)->iSrcLine = iLine;
+}
+#endif /* SQLITE_VDBE_COVERAGE */
+
+/*
+** Return the opcode for a given address.  If the address is -1, then
+** return the most recently inserted opcode.
+**
+** If a memory allocation error has occurred prior to the calling of this
+** routine, then a pointer to a dummy VdbeOp will be returned.  That opcode
+** is readable but not writable, though it is cast to a writable value.
+** The return of a dummy opcode allows the call to continue functioning
+** after an OOM fault without having to check to see if the return from 
+** this routine is a valid pointer.  But because the dummy.opcode is 0,
+** dummy will never be written to.  This is verified by code inspection and
+** by running with Valgrind.
+*/
+SQLITE_PRIVATE VdbeOp *sqlite3VdbeGetOp(Vdbe *p, int addr){
+  /* C89 specifies that the constant "dummy" will be initialized to all
+  ** zeros, which is correct.  MSVC generates a warning, nevertheless. */
+  static VdbeOp dummy;  /* Ignore the MSVC warning about no initializer */
+  assert( p->magic==VDBE_MAGIC_INIT );
+  if( addr<0 ){
+    addr = p->nOp - 1;
+  }
+  assert( (addr>=0 && addr<p->nOp) || p->db->mallocFailed );
+  if( p->db->mallocFailed ){
+    return (VdbeOp*)&dummy;
+  }else{
+    return &p->aOp[addr];
+  }
+}
+
+#if defined(SQLITE_ENABLE_EXPLAIN_COMMENTS)
+/*
+** Return an integer value for one of the parameters to the opcode pOp
+** determined by character c.
+*/
+static int translateP(char c, const Op *pOp){
+  if( c=='1' ) return pOp->p1;
+  if( c=='2' ) return pOp->p2;
+  if( c=='3' ) return pOp->p3;
+  if( c=='4' ) return pOp->p4.i;
+  return pOp->p5;
+}
+
+/*
+** Compute a string for the "comment" field of a VDBE opcode listing.
+**
+** The Synopsis: field in comments in the vdbe.c source file gets converted
+** to an extra string that is appended to the sqlite3OpcodeName().  In the
+** absence of other comments, this synopsis becomes the comment on the opcode.
+** Some translation occurs:
+**
+**       "PX"      ->  "r[X]"
+**       "PX@PY"   ->  "r[X..X+Y-1]"  or "r[x]" if y is 0 or 1
+**       "PX@PY+1" ->  "r[X..X+Y]"    or "r[x]" if y is 0
+**       "PY..PY"  ->  "r[X..Y]"      or "r[x]" if y<=x
+*/
+static int displayComment(
+  const Op *pOp,     /* The opcode to be commented */
+  const char *zP4,   /* Previously obtained value for P4 */
+  char *zTemp,       /* Write result here */
+  int nTemp          /* Space available in zTemp[] */
+){
+  const char *zOpName;
+  const char *zSynopsis;
+  int nOpName;
+  int ii, jj;
+  char zAlt[50];
+  zOpName = sqlite3OpcodeName(pOp->opcode);
+  nOpName = sqlite3Strlen30(zOpName);
+  if( zOpName[nOpName+1] ){
+    int seenCom = 0;
+    char c;
+    zSynopsis = zOpName += nOpName + 1;
+    if( strncmp(zSynopsis,"IF ",3)==0 ){
+      if( pOp->p5 & SQLITE_STOREP2 ){
+        sqlite3_snprintf(sizeof(zAlt), zAlt, "r[P2] = (%s)", zSynopsis+3);
+      }else{
+        sqlite3_snprintf(sizeof(zAlt), zAlt, "if %s goto P2", zSynopsis+3);
+      }
+      zSynopsis = zAlt;
+    }
+    for(ii=jj=0; jj<nTemp-1 && (c = zSynopsis[ii])!=0; ii++){
+      if( c=='P' ){
+        c = zSynopsis[++ii];
+        if( c=='4' ){
+          sqlite3_snprintf(nTemp-jj, zTemp+jj, "%s", zP4);
+        }else if( c=='X' ){
+          sqlite3_snprintf(nTemp-jj, zTemp+jj, "%s", pOp->zComment);
+          seenCom = 1;
+        }else{
+          int v1 = translateP(c, pOp);
+          int v2;
+          sqlite3_snprintf(nTemp-jj, zTemp+jj, "%d", v1);
+          if( strncmp(zSynopsis+ii+1, "@P", 2)==0 ){
+            ii += 3;
+            jj += sqlite3Strlen30(zTemp+jj);
+            v2 = translateP(zSynopsis[ii], pOp);
+            if( strncmp(zSynopsis+ii+1,"+1",2)==0 ){
+              ii += 2;
+              v2++;
+            }
+            if( v2>1 ){
+              sqlite3_snprintf(nTemp-jj, zTemp+jj, "..%d", v1+v2-1);
+            }
+          }else if( strncmp(zSynopsis+ii+1, "..P3", 4)==0 && pOp->p3==0 ){
+            ii += 4;
+          }
+        }
+        jj += sqlite3Strlen30(zTemp+jj);
+      }else{
+        zTemp[jj++] = c;
+      }
+    }
+    if( !seenCom && jj<nTemp-5 && pOp->zComment ){
+      sqlite3_snprintf(nTemp-jj, zTemp+jj, "; %s", pOp->zComment);
+      jj += sqlite3Strlen30(zTemp+jj);
+    }
+    if( jj<nTemp ) zTemp[jj] = 0;
+  }else if( pOp->zComment ){
+    sqlite3_snprintf(nTemp, zTemp, "%s", pOp->zComment);
+    jj = sqlite3Strlen30(zTemp);
+  }else{
+    zTemp[0] = 0;
+    jj = 0;
+  }
+  return jj;
+}
+#endif /* SQLITE_DEBUG */
+
+#if VDBE_DISPLAY_P4 && defined(SQLITE_ENABLE_CURSOR_HINTS)
+/*
+** Translate the P4.pExpr value for an OP_CursorHint opcode into text
+** that can be displayed in the P4 column of EXPLAIN output.
+*/
+static void displayP4Expr(StrAccum *p, Expr *pExpr){
+  const char *zOp = 0;
+  switch( pExpr->op ){
+    case TK_STRING:
+      sqlite3XPrintf(p, "%Q", pExpr->u.zToken);
+      break;
+    case TK_INTEGER:
+      sqlite3XPrintf(p, "%d", pExpr->u.iValue);
+      break;
+    case TK_NULL:
+      sqlite3XPrintf(p, "NULL");
+      break;
+    case TK_REGISTER: {
+      sqlite3XPrintf(p, "r[%d]", pExpr->iTable);
+      break;
+    }
+    case TK_COLUMN: {
+      if( pExpr->iColumn<0 ){
+        sqlite3XPrintf(p, "rowid");
+      }else{
+        sqlite3XPrintf(p, "c%d", (int)pExpr->iColumn);
+      }
+      break;
+    }
+    case TK_LT:      zOp = "LT";      break;
+    case TK_LE:      zOp = "LE";      break;
+    case TK_GT:      zOp = "GT";      break;
+    case TK_GE:      zOp = "GE";      break;
+    case TK_NE:      zOp = "NE";      break;
+    case TK_EQ:      zOp = "EQ";      break;
+    case TK_IS:      zOp = "IS";      break;
+    case TK_ISNOT:   zOp = "ISNOT";   break;
+    case TK_AND:     zOp = "AND";     break;
+    case TK_OR:      zOp = "OR";      break;
+    case TK_PLUS:    zOp = "ADD";     break;
+    case TK_STAR:    zOp = "MUL";     break;
+    case TK_MINUS:   zOp = "SUB";     break;
+    case TK_REM:     zOp = "REM";     break;
+    case TK_BITAND:  zOp = "BITAND";  break;
+    case TK_BITOR:   zOp = "BITOR";   break;
+    case TK_SLASH:   zOp = "DIV";     break;
+    case TK_LSHIFT:  zOp = "LSHIFT";  break;
+    case TK_RSHIFT:  zOp = "RSHIFT";  break;
+    case TK_CONCAT:  zOp = "CONCAT";  break;
+    case TK_UMINUS:  zOp = "MINUS";   break;
+    case TK_UPLUS:   zOp = "PLUS";    break;
+    case TK_BITNOT:  zOp = "BITNOT";  break;
+    case TK_NOT:     zOp = "NOT";     break;
+    case TK_ISNULL:  zOp = "ISNULL";  break;
+    case TK_NOTNULL: zOp = "NOTNULL"; break;
+
+    default:
+      sqlite3XPrintf(p, "%s", "expr");
+      break;
+  }
+
+  if( zOp ){
+    sqlite3XPrintf(p, "%s(", zOp);
+    displayP4Expr(p, pExpr->pLeft);
+    if( pExpr->pRight ){
+      sqlite3StrAccumAppend(p, ",", 1);
+      displayP4Expr(p, pExpr->pRight);
+    }
+    sqlite3StrAccumAppend(p, ")", 1);
+  }
+}
+#endif /* VDBE_DISPLAY_P4 && defined(SQLITE_ENABLE_CURSOR_HINTS) */
+
+
+#if VDBE_DISPLAY_P4
+/*
+** Compute a string that describes the P4 parameter for an opcode.
+** Use zTemp for any required temporary buffer space.
+*/
+static char *displayP4(Op *pOp, char *zTemp, int nTemp){
+  char *zP4 = zTemp;
+  StrAccum x;
+  assert( nTemp>=20 );
+  sqlite3StrAccumInit(&x, 0, zTemp, nTemp, 0);
+  switch( pOp->p4type ){
+    case P4_KEYINFO: {
+      int j;
+      KeyInfo *pKeyInfo = pOp->p4.pKeyInfo;
+      assert( pKeyInfo->aSortOrder!=0 );
+      sqlite3XPrintf(&x, "k(%d", pKeyInfo->nField);
+      for(j=0; j<pKeyInfo->nField; j++){
+        CollSeq *pColl = pKeyInfo->aColl[j];
+        const char *zColl = pColl ? pColl->zName : "";
+        if( strcmp(zColl, "BINARY")==0 ) zColl = "B";
+        sqlite3XPrintf(&x, ",%s%s", pKeyInfo->aSortOrder[j] ? "-" : "", zColl);
+      }
+      sqlite3StrAccumAppend(&x, ")", 1);
+      break;
+    }
+#ifdef SQLITE_ENABLE_CURSOR_HINTS
+    case P4_EXPR: {
+      displayP4Expr(&x, pOp->p4.pExpr);
+      break;
+    }
+#endif
+    case P4_COLLSEQ: {
+      CollSeq *pColl = pOp->p4.pColl;
+      sqlite3XPrintf(&x, "(%.20s)", pColl->zName);
+      break;
+    }
+    case P4_FUNCDEF: {
+      FuncDef *pDef = pOp->p4.pFunc;
+      sqlite3XPrintf(&x, "%s(%d)", pDef->zName, pDef->nArg);
+      break;
+    }
+#ifdef SQLITE_DEBUG
+    case P4_FUNCCTX: {
+      FuncDef *pDef = pOp->p4.pCtx->pFunc;
+      sqlite3XPrintf(&x, "%s(%d)", pDef->zName, pDef->nArg);
+      break;
+    }
+#endif
+    case P4_INT64: {
+      sqlite3XPrintf(&x, "%lld", *pOp->p4.pI64);
+      break;
+    }
+    case P4_INT32: {
+      sqlite3XPrintf(&x, "%d", pOp->p4.i);
+      break;
+    }
+    case P4_REAL: {
+      sqlite3XPrintf(&x, "%.16g", *pOp->p4.pReal);
+      break;
+    }
+    case P4_MEM: {
+      Mem *pMem = pOp->p4.pMem;
+      if( pMem->flags & MEM_Str ){
+        zP4 = pMem->z;
+      }else if( pMem->flags & MEM_Int ){
+        sqlite3XPrintf(&x, "%lld", pMem->u.i);
+      }else if( pMem->flags & MEM_Real ){
+        sqlite3XPrintf(&x, "%.16g", pMem->u.r);
+      }else if( pMem->flags & MEM_Null ){
+        zP4 = "NULL";
+      }else{
+        assert( pMem->flags & MEM_Blob );
+        zP4 = "(blob)";
+      }
+      break;
+    }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    case P4_VTAB: {
+      sqlite3_vtab *pVtab = pOp->p4.pVtab->pVtab;
+      sqlite3XPrintf(&x, "vtab:%p", pVtab);
+      break;
+    }
+#endif
+    case P4_INTARRAY: {
+      int i;
+      int *ai = pOp->p4.ai;
+      int n = ai[0];   /* The first element of an INTARRAY is always the
+                       ** count of the number of elements to follow */
+      for(i=1; i<n; i++){
+        sqlite3XPrintf(&x, ",%d", ai[i]);
+      }
+      zTemp[0] = '[';
+      sqlite3StrAccumAppend(&x, "]", 1);
+      break;
+    }
+    case P4_SUBPROGRAM: {
+      sqlite3XPrintf(&x, "program");
+      break;
+    }
+    case P4_ADVANCE: {
+      zTemp[0] = 0;
+      break;
+    }
+    case P4_TABLE: {
+      sqlite3XPrintf(&x, "%s", pOp->p4.pTab->zName);
+      break;
+    }
+    default: {
+      zP4 = pOp->p4.z;
+      if( zP4==0 ){
+        zP4 = zTemp;
+        zTemp[0] = 0;
+      }
+    }
+  }
+  sqlite3StrAccumFinish(&x);
+  assert( zP4!=0 );
+  return zP4;
+}
+#endif /* VDBE_DISPLAY_P4 */
+
+/*
+** Declare to the Vdbe that the BTree object at db->aDb[i] is used.
+**
+** The prepared statements need to know in advance the complete set of
+** attached databases that will be use.  A mask of these databases
+** is maintained in p->btreeMask.  The p->lockMask value is the subset of
+** p->btreeMask of databases that will require a lock.
+*/
+SQLITE_PRIVATE void sqlite3VdbeUsesBtree(Vdbe *p, int i){
+  assert( i>=0 && i<p->db->nDb && i<(int)sizeof(yDbMask)*8 );
+  assert( i<(int)sizeof(p->btreeMask)*8 );
+  DbMaskSet(p->btreeMask, i);
+  if( i!=1 && sqlite3BtreeSharable(p->db->aDb[i].pBt) ){
+    DbMaskSet(p->lockMask, i);
+  }
+}
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE)
+/*
+** If SQLite is compiled to support shared-cache mode and to be threadsafe,
+** this routine obtains the mutex associated with each BtShared structure
+** that may be accessed by the VM passed as an argument. In doing so it also
+** sets the BtShared.db member of each of the BtShared structures, ensuring
+** that the correct busy-handler callback is invoked if required.
+**
+** If SQLite is not threadsafe but does support shared-cache mode, then
+** sqlite3BtreeEnter() is invoked to set the BtShared.db variables
+** of all of BtShared structures accessible via the database handle 
+** associated with the VM.
+**
+** If SQLite is not threadsafe and does not support shared-cache mode, this
+** function is a no-op.
+**
+** The p->btreeMask field is a bitmask of all btrees that the prepared 
+** statement p will ever use.  Let N be the number of bits in p->btreeMask
+** corresponding to btrees that use shared cache.  Then the runtime of
+** this routine is N*N.  But as N is rarely more than 1, this should not
+** be a problem.
+*/
+SQLITE_PRIVATE void sqlite3VdbeEnter(Vdbe *p){
+  int i;
+  sqlite3 *db;
+  Db *aDb;
+  int nDb;
+  if( DbMaskAllZero(p->lockMask) ) return;  /* The common case */
+  db = p->db;
+  aDb = db->aDb;
+  nDb = db->nDb;
+  for(i=0; i<nDb; i++){
+    if( i!=1 && DbMaskTest(p->lockMask,i) && ALWAYS(aDb[i].pBt!=0) ){
+      sqlite3BtreeEnter(aDb[i].pBt);
+    }
+  }
+}
+#endif
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
+/*
+** Unlock all of the btrees previously locked by a call to sqlite3VdbeEnter().
+*/
+static SQLITE_NOINLINE void vdbeLeave(Vdbe *p){
+  int i;
+  sqlite3 *db;
+  Db *aDb;
+  int nDb;
+  db = p->db;
+  aDb = db->aDb;
+  nDb = db->nDb;
+  for(i=0; i<nDb; i++){
+    if( i!=1 && DbMaskTest(p->lockMask,i) && ALWAYS(aDb[i].pBt!=0) ){
+      sqlite3BtreeLeave(aDb[i].pBt);
+    }
+  }
+}
+SQLITE_PRIVATE void sqlite3VdbeLeave(Vdbe *p){
+  if( DbMaskAllZero(p->lockMask) ) return;  /* The common case */
+  vdbeLeave(p);
+}
+#endif
+
+#if defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
+/*
+** Print a single opcode.  This routine is used for debugging only.
+*/
+SQLITE_PRIVATE void sqlite3VdbePrintOp(FILE *pOut, int pc, Op *pOp){
+  char *zP4;
+  char zPtr[50];
+  char zCom[100];
+  static const char *zFormat1 = "%4d %-13s %4d %4d %4d %-13s %.2X %s\n";
+  if( pOut==0 ) pOut = stdout;
+  zP4 = displayP4(pOp, zPtr, sizeof(zPtr));
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+  displayComment(pOp, zP4, zCom, sizeof(zCom));
+#else
+  zCom[0] = 0;
+#endif
+  /* NB:  The sqlite3OpcodeName() function is implemented by code created
+  ** by the mkopcodeh.awk and mkopcodec.awk scripts which extract the
+  ** information from the vdbe.c source text */
+  fprintf(pOut, zFormat1, pc, 
+      sqlite3OpcodeName(pOp->opcode), pOp->p1, pOp->p2, pOp->p3, zP4, pOp->p5,
+      zCom
+  );
+  fflush(pOut);
+}
+#endif
+
+/*
+** Initialize an array of N Mem element.
+*/
+static void initMemArray(Mem *p, int N, sqlite3 *db, u16 flags){
+  while( (N--)>0 ){
+    p->db = db;
+    p->flags = flags;
+    p->szMalloc = 0;
+#ifdef SQLITE_DEBUG
+    p->pScopyFrom = 0;
+#endif
+    p++;
+  }
+}
+
+/*
+** Release an array of N Mem elements
+*/
+static void releaseMemArray(Mem *p, int N){
+  if( p && N ){
+    Mem *pEnd = &p[N];
+    sqlite3 *db = p->db;
+    if( db->pnBytesFreed ){
+      do{
+        if( p->szMalloc ) sqlite3DbFree(db, p->zMalloc);
+      }while( (++p)<pEnd );
+      return;
+    }
+    do{
+      assert( (&p[1])==pEnd || p[0].db==p[1].db );
+      assert( sqlite3VdbeCheckMemInvariants(p) );
+
+      /* This block is really an inlined version of sqlite3VdbeMemRelease()
+      ** that takes advantage of the fact that the memory cell value is 
+      ** being set to NULL after releasing any dynamic resources.
+      **
+      ** The justification for duplicating code is that according to 
+      ** callgrind, this causes a certain test case to hit the CPU 4.7 
+      ** percent less (x86 linux, gcc version 4.1.2, -O6) than if 
+      ** sqlite3MemRelease() were called from here. With -O2, this jumps
+      ** to 6.6 percent. The test case is inserting 1000 rows into a table 
+      ** with no indexes using a single prepared INSERT statement, bind() 
+      ** and reset(). Inserts are grouped into a transaction.
+      */
+      testcase( p->flags & MEM_Agg );
+      testcase( p->flags & MEM_Dyn );
+      testcase( p->flags & MEM_Frame );
+      testcase( p->flags & MEM_RowSet );
+      if( p->flags&(MEM_Agg|MEM_Dyn|MEM_Frame|MEM_RowSet) ){
+        sqlite3VdbeMemRelease(p);
+      }else if( p->szMalloc ){
+        sqlite3DbFree(db, p->zMalloc);
+        p->szMalloc = 0;
+      }
+
+      p->flags = MEM_Undefined;
+    }while( (++p)<pEnd );
+  }
+}
+
+/*
+** Delete a VdbeFrame object and its contents. VdbeFrame objects are
+** allocated by the OP_Program opcode in sqlite3VdbeExec().
+*/
+SQLITE_PRIVATE void sqlite3VdbeFrameDelete(VdbeFrame *p){
+  int i;
+  Mem *aMem = VdbeFrameMem(p);
+  VdbeCursor **apCsr = (VdbeCursor **)&aMem[p->nChildMem];
+  for(i=0; i<p->nChildCsr; i++){
+    sqlite3VdbeFreeCursor(p->v, apCsr[i]);
+  }
+  releaseMemArray(aMem, p->nChildMem);
+  sqlite3VdbeDeleteAuxData(p->v->db, &p->pAuxData, -1, 0);
+  sqlite3DbFree(p->v->db, p);
+}
+
+#ifndef SQLITE_OMIT_EXPLAIN
+/*
+** Give a listing of the program in the virtual machine.
+**
+** The interface is the same as sqlite3VdbeExec().  But instead of
+** running the code, it invokes the callback once for each instruction.
+** This feature is used to implement "EXPLAIN".
+**
+** When p->explain==1, each instruction is listed.  When
+** p->explain==2, only OP_Explain instructions are listed and these
+** are shown in a different format.  p->explain==2 is used to implement
+** EXPLAIN QUERY PLAN.
+**
+** When p->explain==1, first the main program is listed, then each of
+** the trigger subprograms are listed one by one.
+*/
+SQLITE_PRIVATE int sqlite3VdbeList(
+  Vdbe *p                   /* The VDBE */
+){
+  int nRow;                            /* Stop when row count reaches this */
+  int nSub = 0;                        /* Number of sub-vdbes seen so far */
+  SubProgram **apSub = 0;              /* Array of sub-vdbes */
+  Mem *pSub = 0;                       /* Memory cell hold array of subprogs */
+  sqlite3 *db = p->db;                 /* The database connection */
+  int i;                               /* Loop counter */
+  int rc = SQLITE_OK;                  /* Return code */
+  Mem *pMem = &p->aMem[1];             /* First Mem of result set */
+
+  assert( p->explain );
+  assert( p->magic==VDBE_MAGIC_RUN );
+  assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY || p->rc==SQLITE_NOMEM );
+
+  /* Even though this opcode does not use dynamic strings for
+  ** the result, result columns may become dynamic if the user calls
+  ** sqlite3_column_text16(), causing a translation to UTF-16 encoding.
+  */
+  releaseMemArray(pMem, 8);
+  p->pResultSet = 0;
+
+  if( p->rc==SQLITE_NOMEM_BKPT ){
+    /* This happens if a malloc() inside a call to sqlite3_column_text() or
+    ** sqlite3_column_text16() failed.  */
+    sqlite3OomFault(db);
+    return SQLITE_ERROR;
+  }
+
+  /* When the number of output rows reaches nRow, that means the
+  ** listing has finished and sqlite3_step() should return SQLITE_DONE.
+  ** nRow is the sum of the number of rows in the main program, plus
+  ** the sum of the number of rows in all trigger subprograms encountered
+  ** so far.  The nRow value will increase as new trigger subprograms are
+  ** encountered, but p->pc will eventually catch up to nRow.
+  */
+  nRow = p->nOp;
+  if( p->explain==1 ){
+    /* The first 8 memory cells are used for the result set.  So we will
+    ** commandeer the 9th cell to use as storage for an array of pointers
+    ** to trigger subprograms.  The VDBE is guaranteed to have at least 9
+    ** cells.  */
+    assert( p->nMem>9 );
+    pSub = &p->aMem[9];
+    if( pSub->flags&MEM_Blob ){
+      /* On the first call to sqlite3_step(), pSub will hold a NULL.  It is
+      ** initialized to a BLOB by the P4_SUBPROGRAM processing logic below */
+      nSub = pSub->n/sizeof(Vdbe*);
+      apSub = (SubProgram **)pSub->z;
+    }
+    for(i=0; i<nSub; i++){
+      nRow += apSub[i]->nOp;
+    }
+  }
+
+  do{
+    i = p->pc++;
+  }while( i<nRow && p->explain==2 && p->aOp[i].opcode!=OP_Explain );
+  if( i>=nRow ){
+    p->rc = SQLITE_OK;
+    rc = SQLITE_DONE;
+  }else if( db->u1.isInterrupted ){
+    p->rc = SQLITE_INTERRUPT;
+    rc = SQLITE_ERROR;
+    sqlite3VdbeError(p, sqlite3ErrStr(p->rc));
+  }else{
+    char *zP4;
+    Op *pOp;
+    if( i<p->nOp ){
+      /* The output line number is small enough that we are still in the
+      ** main program. */
+      pOp = &p->aOp[i];
+    }else{
+      /* We are currently listing subprograms.  Figure out which one and
+      ** pick up the appropriate opcode. */
+      int j;
+      i -= p->nOp;
+      for(j=0; i>=apSub[j]->nOp; j++){
+        i -= apSub[j]->nOp;
+      }
+      pOp = &apSub[j]->aOp[i];
+    }
+    if( p->explain==1 ){
+      pMem->flags = MEM_Int;
+      pMem->u.i = i;                                /* Program counter */
+      pMem++;
+  
+      pMem->flags = MEM_Static|MEM_Str|MEM_Term;
+      pMem->z = (char*)sqlite3OpcodeName(pOp->opcode); /* Opcode */
+      assert( pMem->z!=0 );
+      pMem->n = sqlite3Strlen30(pMem->z);
+      pMem->enc = SQLITE_UTF8;
+      pMem++;
+
+      /* When an OP_Program opcode is encounter (the only opcode that has
+      ** a P4_SUBPROGRAM argument), expand the size of the array of subprograms
+      ** kept in p->aMem[9].z to hold the new program - assuming this subprogram
+      ** has not already been seen.
+      */
+      if( pOp->p4type==P4_SUBPROGRAM ){
+        int nByte = (nSub+1)*sizeof(SubProgram*);
+        int j;
+        for(j=0; j<nSub; j++){
+          if( apSub[j]==pOp->p4.pProgram ) break;
+        }
+        if( j==nSub && SQLITE_OK==sqlite3VdbeMemGrow(pSub, nByte, nSub!=0) ){
+          apSub = (SubProgram **)pSub->z;
+          apSub[nSub++] = pOp->p4.pProgram;
+          pSub->flags |= MEM_Blob;
+          pSub->n = nSub*sizeof(SubProgram*);
+        }
+      }
+    }
+
+    pMem->flags = MEM_Int;
+    pMem->u.i = pOp->p1;                          /* P1 */
+    pMem++;
+
+    pMem->flags = MEM_Int;
+    pMem->u.i = pOp->p2;                          /* P2 */
+    pMem++;
+
+    pMem->flags = MEM_Int;
+    pMem->u.i = pOp->p3;                          /* P3 */
+    pMem++;
+
+    if( sqlite3VdbeMemClearAndResize(pMem, 100) ){ /* P4 */
+      assert( p->db->mallocFailed );
+      return SQLITE_ERROR;
+    }
+    pMem->flags = MEM_Str|MEM_Term;
+    zP4 = displayP4(pOp, pMem->z, pMem->szMalloc);
+    if( zP4!=pMem->z ){
+      pMem->n = 0;
+      sqlite3VdbeMemSetStr(pMem, zP4, -1, SQLITE_UTF8, 0);
+    }else{
+      assert( pMem->z!=0 );
+      pMem->n = sqlite3Strlen30(pMem->z);
+      pMem->enc = SQLITE_UTF8;
+    }
+    pMem++;
+
+    if( p->explain==1 ){
+      if( sqlite3VdbeMemClearAndResize(pMem, 4) ){
+        assert( p->db->mallocFailed );
+        return SQLITE_ERROR;
+      }
+      pMem->flags = MEM_Str|MEM_Term;
+      pMem->n = 2;
+      sqlite3_snprintf(3, pMem->z, "%.2x", pOp->p5);   /* P5 */
+      pMem->enc = SQLITE_UTF8;
+      pMem++;
+  
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+      if( sqlite3VdbeMemClearAndResize(pMem, 500) ){
+        assert( p->db->mallocFailed );
+        return SQLITE_ERROR;
+      }
+      pMem->flags = MEM_Str|MEM_Term;
+      pMem->n = displayComment(pOp, zP4, pMem->z, 500);
+      pMem->enc = SQLITE_UTF8;
+#else
+      pMem->flags = MEM_Null;                       /* Comment */
+#endif
+    }
+
+    p->nResColumn = 8 - 4*(p->explain-1);
+    p->pResultSet = &p->aMem[1];
+    p->rc = SQLITE_OK;
+    rc = SQLITE_ROW;
+  }
+  return rc;
+}
+#endif /* SQLITE_OMIT_EXPLAIN */
+
+#ifdef SQLITE_DEBUG
+/*
+** Print the SQL that was used to generate a VDBE program.
+*/
+SQLITE_PRIVATE void sqlite3VdbePrintSql(Vdbe *p){
+  const char *z = 0;
+  if( p->zSql ){
+    z = p->zSql;
+  }else if( p->nOp>=1 ){
+    const VdbeOp *pOp = &p->aOp[0];
+    if( pOp->opcode==OP_Init && pOp->p4.z!=0 ){
+      z = pOp->p4.z;
+      while( sqlite3Isspace(*z) ) z++;
+    }
+  }
+  if( z ) printf("SQL: [%s]\n", z);
+}
+#endif
+
+#if !defined(SQLITE_OMIT_TRACE) && defined(SQLITE_ENABLE_IOTRACE)
+/*
+** Print an IOTRACE message showing SQL content.
+*/
+SQLITE_PRIVATE void sqlite3VdbeIOTraceSql(Vdbe *p){
+  int nOp = p->nOp;
+  VdbeOp *pOp;
+  if( sqlite3IoTrace==0 ) return;
+  if( nOp<1 ) return;
+  pOp = &p->aOp[0];
+  if( pOp->opcode==OP_Init && pOp->p4.z!=0 ){
+    int i, j;
+    char z[1000];
+    sqlite3_snprintf(sizeof(z), z, "%s", pOp->p4.z);
+    for(i=0; sqlite3Isspace(z[i]); i++){}
+    for(j=0; z[i]; i++){
+      if( sqlite3Isspace(z[i]) ){
+        if( z[i-1]!=' ' ){
+          z[j++] = ' ';
+        }
+      }else{
+        z[j++] = z[i];
+      }
+    }
+    z[j] = 0;
+    sqlite3IoTrace("SQL %s\n", z);
+  }
+}
+#endif /* !SQLITE_OMIT_TRACE && SQLITE_ENABLE_IOTRACE */
+
+/* An instance of this object describes bulk memory available for use
+** by subcomponents of a prepared statement.  Space is allocated out
+** of a ReusableSpace object by the allocSpace() routine below.
+*/
+struct ReusableSpace {
+  u8 *pSpace;          /* Available memory */
+  int nFree;           /* Bytes of available memory */
+  int nNeeded;         /* Total bytes that could not be allocated */
+};
+
+/* Try to allocate nByte bytes of 8-byte aligned bulk memory for pBuf
+** from the ReusableSpace object.  Return a pointer to the allocated
+** memory on success.  If insufficient memory is available in the
+** ReusableSpace object, increase the ReusableSpace.nNeeded
+** value by the amount needed and return NULL.
+**
+** If pBuf is not initially NULL, that means that the memory has already
+** been allocated by a prior call to this routine, so just return a copy
+** of pBuf and leave ReusableSpace unchanged.
+**
+** This allocator is employed to repurpose unused slots at the end of the
+** opcode array of prepared state for other memory needs of the prepared
+** statement.
+*/
+static void *allocSpace(
+  struct ReusableSpace *p,  /* Bulk memory available for allocation */
+  void *pBuf,               /* Pointer to a prior allocation */
+  int nByte                 /* Bytes of memory needed */
+){
+  assert( EIGHT_BYTE_ALIGNMENT(p->pSpace) );
+  if( pBuf==0 ){
+    nByte = ROUND8(nByte);
+    if( nByte <= p->nFree ){
+      p->nFree -= nByte;
+      pBuf = &p->pSpace[p->nFree];
+    }else{
+      p->nNeeded += nByte;
+    }
+  }
+  assert( EIGHT_BYTE_ALIGNMENT(pBuf) );
+  return pBuf;
+}
+
+/*
+** Rewind the VDBE back to the beginning in preparation for
+** running it.
+*/
+SQLITE_PRIVATE void sqlite3VdbeRewind(Vdbe *p){
+#if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)
+  int i;
+#endif
+  assert( p!=0 );
+  assert( p->magic==VDBE_MAGIC_INIT || p->magic==VDBE_MAGIC_RESET );
+
+  /* There should be at least one opcode.
+  */
+  assert( p->nOp>0 );
+
+  /* Set the magic to VDBE_MAGIC_RUN sooner rather than later. */
+  p->magic = VDBE_MAGIC_RUN;
+
+#ifdef SQLITE_DEBUG
+  for(i=0; i<p->nMem; i++){
+    assert( p->aMem[i].db==p->db );
+  }
+#endif
+  p->pc = -1;
+  p->rc = SQLITE_OK;
+  p->errorAction = OE_Abort;
+  p->nChange = 0;
+  p->cacheCtr = 1;
+  p->minWriteFileFormat = 255;
+  p->iStatement = 0;
+  p->nFkConstraint = 0;
+#ifdef VDBE_PROFILE
+  for(i=0; i<p->nOp; i++){
+    p->aOp[i].cnt = 0;
+    p->aOp[i].cycles = 0;
+  }
+#endif
+}
+
+/*
+** Prepare a virtual machine for execution for the first time after
+** creating the virtual machine.  This involves things such
+** as allocating registers and initializing the program counter.
+** After the VDBE has be prepped, it can be executed by one or more
+** calls to sqlite3VdbeExec().  
+**
+** This function may be called exactly once on each virtual machine.
+** After this routine is called the VM has been "packaged" and is ready
+** to run.  After this routine is called, further calls to 
+** sqlite3VdbeAddOp() functions are prohibited.  This routine disconnects
+** the Vdbe from the Parse object that helped generate it so that the
+** the Vdbe becomes an independent entity and the Parse object can be
+** destroyed.
+**
+** Use the sqlite3VdbeRewind() procedure to restore a virtual machine back
+** to its initial state after it has been run.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMakeReady(
+  Vdbe *p,                       /* The VDBE */
+  Parse *pParse                  /* Parsing context */
+){
+  sqlite3 *db;                   /* The database connection */
+  int nVar;                      /* Number of parameters */
+  int nMem;                      /* Number of VM memory registers */
+  int nCursor;                   /* Number of cursors required */
+  int nArg;                      /* Number of arguments in subprograms */
+  int n;                         /* Loop counter */
+  struct ReusableSpace x;        /* Reusable bulk memory */
+
+  assert( p!=0 );
+  assert( p->nOp>0 );
+  assert( pParse!=0 );
+  assert( p->magic==VDBE_MAGIC_INIT );
+  assert( pParse==p->pParse );
+  db = p->db;
+  assert( db->mallocFailed==0 );
+  nVar = pParse->nVar;
+  nMem = pParse->nMem;
+  nCursor = pParse->nTab;
+  nArg = pParse->nMaxArg;
+  
+  /* Each cursor uses a memory cell.  The first cursor (cursor 0) can
+  ** use aMem[0] which is not otherwise used by the VDBE program.  Allocate
+  ** space at the end of aMem[] for cursors 1 and greater.
+  ** See also: allocateCursor().
+  */
+  nMem += nCursor;
+  if( nCursor==0 && nMem>0 ) nMem++;  /* Space for aMem[0] even if not used */
+
+  /* Figure out how much reusable memory is available at the end of the
+  ** opcode array.  This extra memory will be reallocated for other elements
+  ** of the prepared statement.
+  */
+  n = ROUND8(sizeof(Op)*p->nOp);              /* Bytes of opcode memory used */
+  x.pSpace = &((u8*)p->aOp)[n];               /* Unused opcode memory */
+  assert( EIGHT_BYTE_ALIGNMENT(x.pSpace) );
+  x.nFree = ROUNDDOWN8(pParse->szOpAlloc - n);  /* Bytes of unused memory */
+  assert( x.nFree>=0 );
+  assert( EIGHT_BYTE_ALIGNMENT(&x.pSpace[x.nFree]) );
+
+  resolveP2Values(p, &nArg);
+  p->usesStmtJournal = (u8)(pParse->isMultiWrite && pParse->mayAbort);
+  if( pParse->explain && nMem<10 ){
+    nMem = 10;
+  }
+  p->expired = 0;
+
+  /* Memory for registers, parameters, cursor, etc, is allocated in one or two
+  ** passes.  On the first pass, we try to reuse unused memory at the 
+  ** end of the opcode array.  If we are unable to satisfy all memory
+  ** requirements by reusing the opcode array tail, then the second
+  ** pass will fill in the remainder using a fresh memory allocation.  
+  **
+  ** This two-pass approach that reuses as much memory as possible from
+  ** the leftover memory at the end of the opcode array.  This can significantly
+  ** reduce the amount of memory held by a prepared statement.
+  */
+  do {
+    x.nNeeded = 0;
+    p->aMem = allocSpace(&x, p->aMem, nMem*sizeof(Mem));
+    p->aVar = allocSpace(&x, p->aVar, nVar*sizeof(Mem));
+    p->apArg = allocSpace(&x, p->apArg, nArg*sizeof(Mem*));
+    p->apCsr = allocSpace(&x, p->apCsr, nCursor*sizeof(VdbeCursor*));
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+    p->anExec = allocSpace(&x, p->anExec, p->nOp*sizeof(i64));
+#endif
+    if( x.nNeeded==0 ) break;
+    x.pSpace = p->pFree = sqlite3DbMallocRawNN(db, x.nNeeded);
+    x.nFree = x.nNeeded;
+  }while( !db->mallocFailed );
+
+  p->nzVar = pParse->nzVar;
+  p->azVar = pParse->azVar;
+  pParse->nzVar =  0;
+  pParse->azVar = 0;
+  p->explain = pParse->explain;
+  if( db->mallocFailed ){
+    p->nVar = 0;
+    p->nCursor = 0;
+    p->nMem = 0;
+  }else{
+    p->nCursor = nCursor;
+    p->nVar = (ynVar)nVar;
+    initMemArray(p->aVar, nVar, db, MEM_Null);
+    p->nMem = nMem;
+    initMemArray(p->aMem, nMem, db, MEM_Undefined);
+    memset(p->apCsr, 0, nCursor*sizeof(VdbeCursor*));
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+    memset(p->anExec, 0, p->nOp*sizeof(i64));
+#endif
+  }
+  sqlite3VdbeRewind(p);
+}
+
+/*
+** Close a VDBE cursor and release all the resources that cursor 
+** happens to hold.
+*/
+SQLITE_PRIVATE void sqlite3VdbeFreeCursor(Vdbe *p, VdbeCursor *pCx){
+  if( pCx==0 ){
+    return;
+  }
+  assert( pCx->pBt==0 || pCx->eCurType==CURTYPE_BTREE );
+  switch( pCx->eCurType ){
+    case CURTYPE_SORTER: {
+      sqlite3VdbeSorterClose(p->db, pCx);
+      break;
+    }
+    case CURTYPE_BTREE: {
+      if( pCx->pBt ){
+        sqlite3BtreeClose(pCx->pBt);
+        /* The pCx->pCursor will be close automatically, if it exists, by
+        ** the call above. */
+      }else{
+        assert( pCx->uc.pCursor!=0 );
+        sqlite3BtreeCloseCursor(pCx->uc.pCursor);
+      }
+      break;
+    }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    case CURTYPE_VTAB: {
+      sqlite3_vtab_cursor *pVCur = pCx->uc.pVCur;
+      const sqlite3_module *pModule = pVCur->pVtab->pModule;
+      assert( pVCur->pVtab->nRef>0 );
+      pVCur->pVtab->nRef--;
+      pModule->xClose(pVCur);
+      break;
+    }
+#endif
+  }
+}
+
+/*
+** Close all cursors in the current frame.
+*/
+static void closeCursorsInFrame(Vdbe *p){
+  if( p->apCsr ){
+    int i;
+    for(i=0; i<p->nCursor; i++){
+      VdbeCursor *pC = p->apCsr[i];
+      if( pC ){
+        sqlite3VdbeFreeCursor(p, pC);
+        p->apCsr[i] = 0;
+      }
+    }
+  }
+}
+
+/*
+** Copy the values stored in the VdbeFrame structure to its Vdbe. This
+** is used, for example, when a trigger sub-program is halted to restore
+** control to the main program.
+*/
+SQLITE_PRIVATE int sqlite3VdbeFrameRestore(VdbeFrame *pFrame){
+  Vdbe *v = pFrame->v;
+  closeCursorsInFrame(v);
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+  v->anExec = pFrame->anExec;
+#endif
+  v->aOp = pFrame->aOp;
+  v->nOp = pFrame->nOp;
+  v->aMem = pFrame->aMem;
+  v->nMem = pFrame->nMem;
+  v->apCsr = pFrame->apCsr;
+  v->nCursor = pFrame->nCursor;
+  v->db->lastRowid = pFrame->lastRowid;
+  v->nChange = pFrame->nChange;
+  v->db->nChange = pFrame->nDbChange;
+  sqlite3VdbeDeleteAuxData(v->db, &v->pAuxData, -1, 0);
+  v->pAuxData = pFrame->pAuxData;
+  pFrame->pAuxData = 0;
+  return pFrame->pc;
+}
+
+/*
+** Close all cursors.
+**
+** Also release any dynamic memory held by the VM in the Vdbe.aMem memory 
+** cell array. This is necessary as the memory cell array may contain
+** pointers to VdbeFrame objects, which may in turn contain pointers to
+** open cursors.
+*/
+static void closeAllCursors(Vdbe *p){
+  if( p->pFrame ){
+    VdbeFrame *pFrame;
+    for(pFrame=p->pFrame; pFrame->pParent; pFrame=pFrame->pParent);
+    sqlite3VdbeFrameRestore(pFrame);
+    p->pFrame = 0;
+    p->nFrame = 0;
+  }
+  assert( p->nFrame==0 );
+  closeCursorsInFrame(p);
+  if( p->aMem ){
+    releaseMemArray(p->aMem, p->nMem);
+  }
+  while( p->pDelFrame ){
+    VdbeFrame *pDel = p->pDelFrame;
+    p->pDelFrame = pDel->pParent;
+    sqlite3VdbeFrameDelete(pDel);
+  }
+
+  /* Delete any auxdata allocations made by the VM */
+  if( p->pAuxData ) sqlite3VdbeDeleteAuxData(p->db, &p->pAuxData, -1, 0);
+  assert( p->pAuxData==0 );
+}
+
+/*
+** Clean up the VM after a single run.
+*/
+static void Cleanup(Vdbe *p){
+  sqlite3 *db = p->db;
+
+#ifdef SQLITE_DEBUG
+  /* Execute assert() statements to ensure that the Vdbe.apCsr[] and 
+  ** Vdbe.aMem[] arrays have already been cleaned up.  */
+  int i;
+  if( p->apCsr ) for(i=0; i<p->nCursor; i++) assert( p->apCsr[i]==0 );
+  if( p->aMem ){
+    for(i=0; i<p->nMem; i++) assert( p->aMem[i].flags==MEM_Undefined );
+  }
+#endif
+
+  sqlite3DbFree(db, p->zErrMsg);
+  p->zErrMsg = 0;
+  p->pResultSet = 0;
+}
+
+/*
+** Set the number of result columns that will be returned by this SQL
+** statement. This is now set at compile time, rather than during
+** execution of the vdbe program so that sqlite3_column_count() can
+** be called on an SQL statement before sqlite3_step().
+*/
+SQLITE_PRIVATE void sqlite3VdbeSetNumCols(Vdbe *p, int nResColumn){
+  Mem *pColName;
+  int n;
+  sqlite3 *db = p->db;
+
+  releaseMemArray(p->aColName, p->nResColumn*COLNAME_N);
+  sqlite3DbFree(db, p->aColName);
+  n = nResColumn*COLNAME_N;
+  p->nResColumn = (u16)nResColumn;
+  p->aColName = pColName = (Mem*)sqlite3DbMallocRawNN(db, sizeof(Mem)*n );
+  if( p->aColName==0 ) return;
+  initMemArray(p->aColName, n, p->db, MEM_Null);
+}
+
+/*
+** Set the name of the idx'th column to be returned by the SQL statement.
+** zName must be a pointer to a nul terminated string.
+**
+** This call must be made after a call to sqlite3VdbeSetNumCols().
+**
+** The final parameter, xDel, must be one of SQLITE_DYNAMIC, SQLITE_STATIC
+** or SQLITE_TRANSIENT. If it is SQLITE_DYNAMIC, then the buffer pointed
+** to by zName will be freed by sqlite3DbFree() when the vdbe is destroyed.
+*/
+SQLITE_PRIVATE int sqlite3VdbeSetColName(
+  Vdbe *p,                         /* Vdbe being configured */
+  int idx,                         /* Index of column zName applies to */
+  int var,                         /* One of the COLNAME_* constants */
+  const char *zName,               /* Pointer to buffer containing name */
+  void (*xDel)(void*)              /* Memory management strategy for zName */
+){
+  int rc;
+  Mem *pColName;
+  assert( idx<p->nResColumn );
+  assert( var<COLNAME_N );
+  if( p->db->mallocFailed ){
+    assert( !zName || xDel!=SQLITE_DYNAMIC );
+    return SQLITE_NOMEM_BKPT;
+  }
+  assert( p->aColName!=0 );
+  pColName = &(p->aColName[idx+var*p->nResColumn]);
+  rc = sqlite3VdbeMemSetStr(pColName, zName, -1, SQLITE_UTF8, xDel);
+  assert( rc!=0 || !zName || (pColName->flags&MEM_Term)!=0 );
+  return rc;
+}
+
+/*
+** A read or write transaction may or may not be active on database handle
+** db. If a transaction is active, commit it. If there is a
+** write-transaction spanning more than one database file, this routine
+** takes care of the master journal trickery.
+*/
+static int vdbeCommit(sqlite3 *db, Vdbe *p){
+  int i;
+  int nTrans = 0;  /* Number of databases with an active write-transaction
+                   ** that are candidates for a two-phase commit using a
+                   ** master-journal */
+  int rc = SQLITE_OK;
+  int needXcommit = 0;
+
+#ifdef SQLITE_OMIT_VIRTUALTABLE
+  /* With this option, sqlite3VtabSync() is defined to be simply 
+  ** SQLITE_OK so p is not used. 
+  */
+  UNUSED_PARAMETER(p);
+#endif
+
+  /* Before doing anything else, call the xSync() callback for any
+  ** virtual module tables written in this transaction. This has to
+  ** be done before determining whether a master journal file is 
+  ** required, as an xSync() callback may add an attached database
+  ** to the transaction.
+  */
+  rc = sqlite3VtabSync(db, p);
+
+  /* This loop determines (a) if the commit hook should be invoked and
+  ** (b) how many database files have open write transactions, not 
+  ** including the temp database. (b) is important because if more than 
+  ** one database file has an open write transaction, a master journal
+  ** file is required for an atomic commit.
+  */ 
+  for(i=0; rc==SQLITE_OK && i<db->nDb; i++){ 
+    Btree *pBt = db->aDb[i].pBt;
+    if( sqlite3BtreeIsInTrans(pBt) ){
+      /* Whether or not a database might need a master journal depends upon
+      ** its journal mode (among other things).  This matrix determines which
+      ** journal modes use a master journal and which do not */
+      static const u8 aMJNeeded[] = {
+        /* DELETE   */  1,
+        /* PERSIST   */ 1,
+        /* OFF       */ 0,
+        /* TRUNCATE  */ 1,
+        /* MEMORY    */ 0,
+        /* WAL       */ 0
+      };
+      Pager *pPager;   /* Pager associated with pBt */
+      needXcommit = 1;
+      sqlite3BtreeEnter(pBt);
+      pPager = sqlite3BtreePager(pBt);
+      if( db->aDb[i].safety_level!=PAGER_SYNCHRONOUS_OFF
+       && aMJNeeded[sqlite3PagerGetJournalMode(pPager)]
+      ){ 
+        assert( i!=1 );
+        nTrans++;
+      }
+      rc = sqlite3PagerExclusiveLock(pPager);
+      sqlite3BtreeLeave(pBt);
+    }
+  }
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+
+  /* If there are any write-transactions at all, invoke the commit hook */
+  if( needXcommit && db->xCommitCallback ){
+    rc = db->xCommitCallback(db->pCommitArg);
+    if( rc ){
+      return SQLITE_CONSTRAINT_COMMITHOOK;
+    }
+  }
+
+  /* The simple case - no more than one database file (not counting the
+  ** TEMP database) has a transaction active.   There is no need for the
+  ** master-journal.
+  **
+  ** If the return value of sqlite3BtreeGetFilename() is a zero length
+  ** string, it means the main database is :memory: or a temp file.  In 
+  ** that case we do not support atomic multi-file commits, so use the 
+  ** simple case then too.
+  */
+  if( 0==sqlite3Strlen30(sqlite3BtreeGetFilename(db->aDb[0].pBt))
+   || nTrans<=1
+  ){
+    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
+      Btree *pBt = db->aDb[i].pBt;
+      if( pBt ){
+        rc = sqlite3BtreeCommitPhaseOne(pBt, 0);
+      }
+    }
+
+    /* Do the commit only if all databases successfully complete phase 1. 
+    ** If one of the BtreeCommitPhaseOne() calls fails, this indicates an
+    ** IO error while deleting or truncating a journal file. It is unlikely,
+    ** but could happen. In this case abandon processing and return the error.
+    */
+    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
+      Btree *pBt = db->aDb[i].pBt;
+      if( pBt ){
+        rc = sqlite3BtreeCommitPhaseTwo(pBt, 0);
+      }
+    }
+    if( rc==SQLITE_OK ){
+      sqlite3VtabCommit(db);
+    }
+  }
+
+  /* The complex case - There is a multi-file write-transaction active.
+  ** This requires a master journal file to ensure the transaction is
+  ** committed atomically.
+  */
+#ifndef SQLITE_OMIT_DISKIO
+  else{
+    sqlite3_vfs *pVfs = db->pVfs;
+    char *zMaster = 0;   /* File-name for the master journal */
+    char const *zMainFile = sqlite3BtreeGetFilename(db->aDb[0].pBt);
+    sqlite3_file *pMaster = 0;
+    i64 offset = 0;
+    int res;
+    int retryCount = 0;
+    int nMainFile;
+
+    /* Select a master journal file name */
+    nMainFile = sqlite3Strlen30(zMainFile);
+    zMaster = sqlite3MPrintf(db, "%s-mjXXXXXX9XXz", zMainFile);
+    if( zMaster==0 ) return SQLITE_NOMEM_BKPT;
+    do {
+      u32 iRandom;
+      if( retryCount ){
+        if( retryCount>100 ){
+          sqlite3_log(SQLITE_FULL, "MJ delete: %s", zMaster);
+          sqlite3OsDelete(pVfs, zMaster, 0);
+          break;
+        }else if( retryCount==1 ){
+          sqlite3_log(SQLITE_FULL, "MJ collide: %s", zMaster);
+        }
+      }
+      retryCount++;
+      sqlite3_randomness(sizeof(iRandom), &iRandom);
+      sqlite3_snprintf(13, &zMaster[nMainFile], "-mj%06X9%02X",
+                               (iRandom>>8)&0xffffff, iRandom&0xff);
+      /* The antipenultimate character of the master journal name must
+      ** be "9" to avoid name collisions when using 8+3 filenames. */
+      assert( zMaster[sqlite3Strlen30(zMaster)-3]=='9' );
+      sqlite3FileSuffix3(zMainFile, zMaster);
+      rc = sqlite3OsAccess(pVfs, zMaster, SQLITE_ACCESS_EXISTS, &res);
+    }while( rc==SQLITE_OK && res );
+    if( rc==SQLITE_OK ){
+      /* Open the master journal. */
+      rc = sqlite3OsOpenMalloc(pVfs, zMaster, &pMaster, 
+          SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|
+          SQLITE_OPEN_EXCLUSIVE|SQLITE_OPEN_MASTER_JOURNAL, 0
+      );
+    }
+    if( rc!=SQLITE_OK ){
+      sqlite3DbFree(db, zMaster);
+      return rc;
+    }
+ 
+    /* Write the name of each database file in the transaction into the new
+    ** master journal file. If an error occurs at this point close
+    ** and delete the master journal file. All the individual journal files
+    ** still have 'null' as the master journal pointer, so they will roll
+    ** back independently if a failure occurs.
+    */
+    for(i=0; i<db->nDb; i++){
+      Btree *pBt = db->aDb[i].pBt;
+      if( sqlite3BtreeIsInTrans(pBt) ){
+        char const *zFile = sqlite3BtreeGetJournalname(pBt);
+        if( zFile==0 ){
+          continue;  /* Ignore TEMP and :memory: databases */
+        }
+        assert( zFile[0]!=0 );
+        rc = sqlite3OsWrite(pMaster, zFile, sqlite3Strlen30(zFile)+1, offset);
+        offset += sqlite3Strlen30(zFile)+1;
+        if( rc!=SQLITE_OK ){
+          sqlite3OsCloseFree(pMaster);
+          sqlite3OsDelete(pVfs, zMaster, 0);
+          sqlite3DbFree(db, zMaster);
+          return rc;
+        }
+      }
+    }
+
+    /* Sync the master journal file. If the IOCAP_SEQUENTIAL device
+    ** flag is set this is not required.
+    */
+    if( 0==(sqlite3OsDeviceCharacteristics(pMaster)&SQLITE_IOCAP_SEQUENTIAL)
+     && SQLITE_OK!=(rc = sqlite3OsSync(pMaster, SQLITE_SYNC_NORMAL))
+    ){
+      sqlite3OsCloseFree(pMaster);
+      sqlite3OsDelete(pVfs, zMaster, 0);
+      sqlite3DbFree(db, zMaster);
+      return rc;
+    }
+
+    /* Sync all the db files involved in the transaction. The same call
+    ** sets the master journal pointer in each individual journal. If
+    ** an error occurs here, do not delete the master journal file.
+    **
+    ** If the error occurs during the first call to
+    ** sqlite3BtreeCommitPhaseOne(), then there is a chance that the
+    ** master journal file will be orphaned. But we cannot delete it,
+    ** in case the master journal file name was written into the journal
+    ** file before the failure occurred.
+    */
+    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){ 
+      Btree *pBt = db->aDb[i].pBt;
+      if( pBt ){
+        rc = sqlite3BtreeCommitPhaseOne(pBt, zMaster);
+      }
+    }
+    sqlite3OsCloseFree(pMaster);
+    assert( rc!=SQLITE_BUSY );
+    if( rc!=SQLITE_OK ){
+      sqlite3DbFree(db, zMaster);
+      return rc;
+    }
+
+    /* Delete the master journal file. This commits the transaction. After
+    ** doing this the directory is synced again before any individual
+    ** transaction files are deleted.
+    */
+    rc = sqlite3OsDelete(pVfs, zMaster, 1);
+    sqlite3DbFree(db, zMaster);
+    zMaster = 0;
+    if( rc ){
+      return rc;
+    }
+
+    /* All files and directories have already been synced, so the following
+    ** calls to sqlite3BtreeCommitPhaseTwo() are only closing files and
+    ** deleting or truncating journals. If something goes wrong while
+    ** this is happening we don't really care. The integrity of the
+    ** transaction is already guaranteed, but some stray 'cold' journals
+    ** may be lying around. Returning an error code won't help matters.
+    */
+    disable_simulated_io_errors();
+    sqlite3BeginBenignMalloc();
+    for(i=0; i<db->nDb; i++){ 
+      Btree *pBt = db->aDb[i].pBt;
+      if( pBt ){
+        sqlite3BtreeCommitPhaseTwo(pBt, 1);
+      }
+    }
+    sqlite3EndBenignMalloc();
+    enable_simulated_io_errors();
+
+    sqlite3VtabCommit(db);
+  }
+#endif
+
+  return rc;
+}
+
+/* 
+** This routine checks that the sqlite3.nVdbeActive count variable
+** matches the number of vdbe's in the list sqlite3.pVdbe that are
+** currently active. An assertion fails if the two counts do not match.
+** This is an internal self-check only - it is not an essential processing
+** step.
+**
+** This is a no-op if NDEBUG is defined.
+*/
+#ifndef NDEBUG
+static void checkActiveVdbeCnt(sqlite3 *db){
+  Vdbe *p;
+  int cnt = 0;
+  int nWrite = 0;
+  int nRead = 0;
+  p = db->pVdbe;
+  while( p ){
+    if( sqlite3_stmt_busy((sqlite3_stmt*)p) ){
+      cnt++;
+      if( p->readOnly==0 ) nWrite++;
+      if( p->bIsReader ) nRead++;
+    }
+    p = p->pNext;
+  }
+  assert( cnt==db->nVdbeActive );
+  assert( nWrite==db->nVdbeWrite );
+  assert( nRead==db->nVdbeRead );
+}
+#else
+#define checkActiveVdbeCnt(x)
+#endif
+
+/*
+** If the Vdbe passed as the first argument opened a statement-transaction,
+** close it now. Argument eOp must be either SAVEPOINT_ROLLBACK or
+** SAVEPOINT_RELEASE. If it is SAVEPOINT_ROLLBACK, then the statement
+** transaction is rolled back. If eOp is SAVEPOINT_RELEASE, then the 
+** statement transaction is committed.
+**
+** If an IO error occurs, an SQLITE_IOERR_XXX error code is returned. 
+** Otherwise SQLITE_OK.
+*/
+SQLITE_PRIVATE int sqlite3VdbeCloseStatement(Vdbe *p, int eOp){
+  sqlite3 *const db = p->db;
+  int rc = SQLITE_OK;
+
+  /* If p->iStatement is greater than zero, then this Vdbe opened a 
+  ** statement transaction that should be closed here. The only exception
+  ** is that an IO error may have occurred, causing an emergency rollback.
+  ** In this case (db->nStatement==0), and there is nothing to do.
+  */
+  if( db->nStatement && p->iStatement ){
+    int i;
+    const int iSavepoint = p->iStatement-1;
+
+    assert( eOp==SAVEPOINT_ROLLBACK || eOp==SAVEPOINT_RELEASE);
+    assert( db->nStatement>0 );
+    assert( p->iStatement==(db->nStatement+db->nSavepoint) );
+
+    for(i=0; i<db->nDb; i++){ 
+      int rc2 = SQLITE_OK;
+      Btree *pBt = db->aDb[i].pBt;
+      if( pBt ){
+        if( eOp==SAVEPOINT_ROLLBACK ){
+          rc2 = sqlite3BtreeSavepoint(pBt, SAVEPOINT_ROLLBACK, iSavepoint);
+        }
+        if( rc2==SQLITE_OK ){
+          rc2 = sqlite3BtreeSavepoint(pBt, SAVEPOINT_RELEASE, iSavepoint);
+        }
+        if( rc==SQLITE_OK ){
+          rc = rc2;
+        }
+      }
+    }
+    db->nStatement--;
+    p->iStatement = 0;
+
+    if( rc==SQLITE_OK ){
+      if( eOp==SAVEPOINT_ROLLBACK ){
+        rc = sqlite3VtabSavepoint(db, SAVEPOINT_ROLLBACK, iSavepoint);
+      }
+      if( rc==SQLITE_OK ){
+        rc = sqlite3VtabSavepoint(db, SAVEPOINT_RELEASE, iSavepoint);
+      }
+    }
+
+    /* If the statement transaction is being rolled back, also restore the 
+    ** database handles deferred constraint counter to the value it had when 
+    ** the statement transaction was opened.  */
+    if( eOp==SAVEPOINT_ROLLBACK ){
+      db->nDeferredCons = p->nStmtDefCons;
+      db->nDeferredImmCons = p->nStmtDefImmCons;
+    }
+  }
+  return rc;
+}
+
+/*
+** This function is called when a transaction opened by the database 
+** handle associated with the VM passed as an argument is about to be 
+** committed. If there are outstanding deferred foreign key constraint
+** violations, return SQLITE_ERROR. Otherwise, SQLITE_OK.
+**
+** If there are outstanding FK violations and this function returns 
+** SQLITE_ERROR, set the result of the VM to SQLITE_CONSTRAINT_FOREIGNKEY
+** and write an error message to it. Then return SQLITE_ERROR.
+*/
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+SQLITE_PRIVATE int sqlite3VdbeCheckFk(Vdbe *p, int deferred){
+  sqlite3 *db = p->db;
+  if( (deferred && (db->nDeferredCons+db->nDeferredImmCons)>0) 
+   || (!deferred && p->nFkConstraint>0) 
+  ){
+    p->rc = SQLITE_CONSTRAINT_FOREIGNKEY;
+    p->errorAction = OE_Abort;
+    sqlite3VdbeError(p, "FOREIGN KEY constraint failed");
+    return SQLITE_ERROR;
+  }
+  return SQLITE_OK;
+}
+#endif
+
+/*
+** This routine is called the when a VDBE tries to halt.  If the VDBE
+** has made changes and is in autocommit mode, then commit those
+** changes.  If a rollback is needed, then do the rollback.
+**
+** This routine is the only way to move the state of a VM from
+** SQLITE_MAGIC_RUN to SQLITE_MAGIC_HALT.  It is harmless to
+** call this on a VM that is in the SQLITE_MAGIC_HALT state.
+**
+** Return an error code.  If the commit could not complete because of
+** lock contention, return SQLITE_BUSY.  If SQLITE_BUSY is returned, it
+** means the close did not happen and needs to be repeated.
+*/
+SQLITE_PRIVATE int sqlite3VdbeHalt(Vdbe *p){
+  int rc;                         /* Used to store transient return codes */
+  sqlite3 *db = p->db;
+
+  /* This function contains the logic that determines if a statement or
+  ** transaction will be committed or rolled back as a result of the
+  ** execution of this virtual machine. 
+  **
+  ** If any of the following errors occur:
+  **
+  **     SQLITE_NOMEM
+  **     SQLITE_IOERR
+  **     SQLITE_FULL
+  **     SQLITE_INTERRUPT
+  **
+  ** Then the internal cache might have been left in an inconsistent
+  ** state.  We need to rollback the statement transaction, if there is
+  ** one, or the complete transaction if there is no statement transaction.
+  */
+
+  if( db->mallocFailed ){
+    p->rc = SQLITE_NOMEM_BKPT;
+  }
+  closeAllCursors(p);
+  if( p->magic!=VDBE_MAGIC_RUN ){
+    return SQLITE_OK;
+  }
+  checkActiveVdbeCnt(db);
+
+  /* No commit or rollback needed if the program never started or if the
+  ** SQL statement does not read or write a database file.  */
+  if( p->pc>=0 && p->bIsReader ){
+    int mrc;   /* Primary error code from p->rc */
+    int eStatementOp = 0;
+    int isSpecialError;            /* Set to true if a 'special' error */
+
+    /* Lock all btrees used by the statement */
+    sqlite3VdbeEnter(p);
+
+    /* Check for one of the special errors */
+    mrc = p->rc & 0xff;
+    isSpecialError = mrc==SQLITE_NOMEM || mrc==SQLITE_IOERR
+                     || mrc==SQLITE_INTERRUPT || mrc==SQLITE_FULL;
+    if( isSpecialError ){
+      /* If the query was read-only and the error code is SQLITE_INTERRUPT, 
+      ** no rollback is necessary. Otherwise, at least a savepoint 
+      ** transaction must be rolled back to restore the database to a 
+      ** consistent state.
+      **
+      ** Even if the statement is read-only, it is important to perform
+      ** a statement or transaction rollback operation. If the error 
+      ** occurred while writing to the journal, sub-journal or database
+      ** file as part of an effort to free up cache space (see function
+      ** pagerStress() in pager.c), the rollback is required to restore 
+      ** the pager to a consistent state.
+      */
+      if( !p->readOnly || mrc!=SQLITE_INTERRUPT ){
+        if( (mrc==SQLITE_NOMEM || mrc==SQLITE_FULL) && p->usesStmtJournal ){
+          eStatementOp = SAVEPOINT_ROLLBACK;
+        }else{
+          /* We are forced to roll back the active transaction. Before doing
+          ** so, abort any other statements this handle currently has active.
+          */
+          sqlite3RollbackAll(db, SQLITE_ABORT_ROLLBACK);
+          sqlite3CloseSavepoints(db);
+          db->autoCommit = 1;
+          p->nChange = 0;
+        }
+      }
+    }
+
+    /* Check for immediate foreign key violations. */
+    if( p->rc==SQLITE_OK ){
+      sqlite3VdbeCheckFk(p, 0);
+    }
+  
+    /* If the auto-commit flag is set and this is the only active writer 
+    ** VM, then we do either a commit or rollback of the current transaction. 
+    **
+    ** Note: This block also runs if one of the special errors handled 
+    ** above has occurred. 
+    */
+    if( !sqlite3VtabInSync(db) 
+     && db->autoCommit 
+     && db->nVdbeWrite==(p->readOnly==0) 
+    ){
+      if( p->rc==SQLITE_OK || (p->errorAction==OE_Fail && !isSpecialError) ){
+        rc = sqlite3VdbeCheckFk(p, 1);
+        if( rc!=SQLITE_OK ){
+          if( NEVER(p->readOnly) ){
+            sqlite3VdbeLeave(p);
+            return SQLITE_ERROR;
+          }
+          rc = SQLITE_CONSTRAINT_FOREIGNKEY;
+        }else{ 
+          /* The auto-commit flag is true, the vdbe program was successful 
+          ** or hit an 'OR FAIL' constraint and there are no deferred foreign
+          ** key constraints to hold up the transaction. This means a commit 
+          ** is required. */
+          rc = vdbeCommit(db, p);
+        }
+        if( rc==SQLITE_BUSY && p->readOnly ){
+          sqlite3VdbeLeave(p);
+          return SQLITE_BUSY;
+        }else if( rc!=SQLITE_OK ){
+          p->rc = rc;
+          sqlite3RollbackAll(db, SQLITE_OK);
+          p->nChange = 0;
+        }else{
+          db->nDeferredCons = 0;
+          db->nDeferredImmCons = 0;
+          db->flags &= ~SQLITE_DeferFKs;
+          sqlite3CommitInternalChanges(db);
+        }
+      }else{
+        sqlite3RollbackAll(db, SQLITE_OK);
+        p->nChange = 0;
+      }
+      db->nStatement = 0;
+    }else if( eStatementOp==0 ){
+      if( p->rc==SQLITE_OK || p->errorAction==OE_Fail ){
+        eStatementOp = SAVEPOINT_RELEASE;
+      }else if( p->errorAction==OE_Abort ){
+        eStatementOp = SAVEPOINT_ROLLBACK;
+      }else{
+        sqlite3RollbackAll(db, SQLITE_ABORT_ROLLBACK);
+        sqlite3CloseSavepoints(db);
+        db->autoCommit = 1;
+        p->nChange = 0;
+      }
+    }
+  
+    /* If eStatementOp is non-zero, then a statement transaction needs to
+    ** be committed or rolled back. Call sqlite3VdbeCloseStatement() to
+    ** do so. If this operation returns an error, and the current statement
+    ** error code is SQLITE_OK or SQLITE_CONSTRAINT, then promote the
+    ** current statement error code.
+    */
+    if( eStatementOp ){
+      rc = sqlite3VdbeCloseStatement(p, eStatementOp);
+      if( rc ){
+        if( p->rc==SQLITE_OK || (p->rc&0xff)==SQLITE_CONSTRAINT ){
+          p->rc = rc;
+          sqlite3DbFree(db, p->zErrMsg);
+          p->zErrMsg = 0;
+        }
+        sqlite3RollbackAll(db, SQLITE_ABORT_ROLLBACK);
+        sqlite3CloseSavepoints(db);
+        db->autoCommit = 1;
+        p->nChange = 0;
+      }
+    }
+  
+    /* If this was an INSERT, UPDATE or DELETE and no statement transaction
+    ** has been rolled back, update the database connection change-counter. 
+    */
+    if( p->changeCntOn ){
+      if( eStatementOp!=SAVEPOINT_ROLLBACK ){
+        sqlite3VdbeSetChanges(db, p->nChange);
+      }else{
+        sqlite3VdbeSetChanges(db, 0);
+      }
+      p->nChange = 0;
+    }
+
+    /* Release the locks */
+    sqlite3VdbeLeave(p);
+  }
+
+  /* We have successfully halted and closed the VM.  Record this fact. */
+  if( p->pc>=0 ){
+    db->nVdbeActive--;
+    if( !p->readOnly ) db->nVdbeWrite--;
+    if( p->bIsReader ) db->nVdbeRead--;
+    assert( db->nVdbeActive>=db->nVdbeRead );
+    assert( db->nVdbeRead>=db->nVdbeWrite );
+    assert( db->nVdbeWrite>=0 );
+  }
+  p->magic = VDBE_MAGIC_HALT;
+  checkActiveVdbeCnt(db);
+  if( db->mallocFailed ){
+    p->rc = SQLITE_NOMEM_BKPT;
+  }
+
+  /* If the auto-commit flag is set to true, then any locks that were held
+  ** by connection db have now been released. Call sqlite3ConnectionUnlocked() 
+  ** to invoke any required unlock-notify callbacks.
+  */
+  if( db->autoCommit ){
+    sqlite3ConnectionUnlocked(db);
+  }
+
+  assert( db->nVdbeActive>0 || db->autoCommit==0 || db->nStatement==0 );
+  return (p->rc==SQLITE_BUSY ? SQLITE_BUSY : SQLITE_OK);
+}
+
+
+/*
+** Each VDBE holds the result of the most recent sqlite3_step() call
+** in p->rc.  This routine sets that result back to SQLITE_OK.
+*/
+SQLITE_PRIVATE void sqlite3VdbeResetStepResult(Vdbe *p){
+  p->rc = SQLITE_OK;
+}
+
+/*
+** Copy the error code and error message belonging to the VDBE passed
+** as the first argument to its database handle (so that they will be 
+** returned by calls to sqlite3_errcode() and sqlite3_errmsg()).
+**
+** This function does not clear the VDBE error code or message, just
+** copies them to the database handle.
+*/
+SQLITE_PRIVATE int sqlite3VdbeTransferError(Vdbe *p){
+  sqlite3 *db = p->db;
+  int rc = p->rc;
+  if( p->zErrMsg ){
+    db->bBenignMalloc++;
+    sqlite3BeginBenignMalloc();
+    if( db->pErr==0 ) db->pErr = sqlite3ValueNew(db);
+    sqlite3ValueSetStr(db->pErr, -1, p->zErrMsg, SQLITE_UTF8, SQLITE_TRANSIENT);
+    sqlite3EndBenignMalloc();
+    db->bBenignMalloc--;
+    db->errCode = rc;
+  }else{
+    sqlite3Error(db, rc);
+  }
+  return rc;
+}
+
+#ifdef SQLITE_ENABLE_SQLLOG
+/*
+** If an SQLITE_CONFIG_SQLLOG hook is registered and the VM has been run, 
+** invoke it.
+*/
+static void vdbeInvokeSqllog(Vdbe *v){
+  if( sqlite3GlobalConfig.xSqllog && v->rc==SQLITE_OK && v->zSql && v->pc>=0 ){
+    char *zExpanded = sqlite3VdbeExpandSql(v, v->zSql);
+    assert( v->db->init.busy==0 );
+    if( zExpanded ){
+      sqlite3GlobalConfig.xSqllog(
+          sqlite3GlobalConfig.pSqllogArg, v->db, zExpanded, 1
+      );
+      sqlite3DbFree(v->db, zExpanded);
+    }
+  }
+}
+#else
+# define vdbeInvokeSqllog(x)
+#endif
+
+/*
+** Clean up a VDBE after execution but do not delete the VDBE just yet.
+** Write any error messages into *pzErrMsg.  Return the result code.
+**
+** After this routine is run, the VDBE should be ready to be executed
+** again.
+**
+** To look at it another way, this routine resets the state of the
+** virtual machine from VDBE_MAGIC_RUN or VDBE_MAGIC_HALT back to
+** VDBE_MAGIC_INIT.
+*/
+SQLITE_PRIVATE int sqlite3VdbeReset(Vdbe *p){
+  sqlite3 *db;
+  db = p->db;
+
+  /* If the VM did not run to completion or if it encountered an
+  ** error, then it might not have been halted properly.  So halt
+  ** it now.
+  */
+  sqlite3VdbeHalt(p);
+
+  /* If the VDBE has be run even partially, then transfer the error code
+  ** and error message from the VDBE into the main database structure.  But
+  ** if the VDBE has just been set to run but has not actually executed any
+  ** instructions yet, leave the main database error information unchanged.
+  */
+  if( p->pc>=0 ){
+    vdbeInvokeSqllog(p);
+    sqlite3VdbeTransferError(p);
+    sqlite3DbFree(db, p->zErrMsg);
+    p->zErrMsg = 0;
+    if( p->runOnlyOnce ) p->expired = 1;
+  }else if( p->rc && p->expired ){
+    /* The expired flag was set on the VDBE before the first call
+    ** to sqlite3_step(). For consistency (since sqlite3_step() was
+    ** called), set the database error in this case as well.
+    */
+    sqlite3ErrorWithMsg(db, p->rc, p->zErrMsg ? "%s" : 0, p->zErrMsg);
+    sqlite3DbFree(db, p->zErrMsg);
+    p->zErrMsg = 0;
+  }
+
+  /* Reclaim all memory used by the VDBE
+  */
+  Cleanup(p);
+
+  /* Save profiling information from this VDBE run.
+  */
+#ifdef VDBE_PROFILE
+  {
+    FILE *out = fopen("vdbe_profile.out", "a");
+    if( out ){
+      int i;
+      fprintf(out, "---- ");
+      for(i=0; i<p->nOp; i++){
+        fprintf(out, "%02x", p->aOp[i].opcode);
+      }
+      fprintf(out, "\n");
+      if( p->zSql ){
+        char c, pc = 0;
+        fprintf(out, "-- ");
+        for(i=0; (c = p->zSql[i])!=0; i++){
+          if( pc=='\n' ) fprintf(out, "-- ");
+          putc(c, out);
+          pc = c;
+        }
+        if( pc!='\n' ) fprintf(out, "\n");
+      }
+      for(i=0; i<p->nOp; i++){
+        char zHdr[100];
+        sqlite3_snprintf(sizeof(zHdr), zHdr, "%6u %12llu %8llu ",
+           p->aOp[i].cnt,
+           p->aOp[i].cycles,
+           p->aOp[i].cnt>0 ? p->aOp[i].cycles/p->aOp[i].cnt : 0
+        );
+        fprintf(out, "%s", zHdr);
+        sqlite3VdbePrintOp(out, i, &p->aOp[i]);
+      }
+      fclose(out);
+    }
+  }
+#endif
+  p->iCurrentTime = 0;
+  p->magic = VDBE_MAGIC_RESET;
+  return p->rc & db->errMask;
+}
+ 
+/*
+** Clean up and delete a VDBE after execution.  Return an integer which is
+** the result code.  Write any error message text into *pzErrMsg.
+*/
+SQLITE_PRIVATE int sqlite3VdbeFinalize(Vdbe *p){
+  int rc = SQLITE_OK;
+  if( p->magic==VDBE_MAGIC_RUN || p->magic==VDBE_MAGIC_HALT ){
+    rc = sqlite3VdbeReset(p);
+    assert( (rc & p->db->errMask)==rc );
+  }
+  sqlite3VdbeDelete(p);
+  return rc;
+}
+
+/*
+** If parameter iOp is less than zero, then invoke the destructor for
+** all auxiliary data pointers currently cached by the VM passed as
+** the first argument.
+**
+** Or, if iOp is greater than or equal to zero, then the destructor is
+** only invoked for those auxiliary data pointers created by the user 
+** function invoked by the OP_Function opcode at instruction iOp of 
+** VM pVdbe, and only then if:
+**
+**    * the associated function parameter is the 32nd or later (counting
+**      from left to right), or
+**
+**    * the corresponding bit in argument mask is clear (where the first
+**      function parameter corresponds to bit 0 etc.).
+*/
+SQLITE_PRIVATE void sqlite3VdbeDeleteAuxData(sqlite3 *db, AuxData **pp, int iOp, int mask){
+  while( *pp ){
+    AuxData *pAux = *pp;
+    if( (iOp<0)
+     || (pAux->iOp==iOp && (pAux->iArg>31 || !(mask & MASKBIT32(pAux->iArg))))
+    ){
+      testcase( pAux->iArg==31 );
+      if( pAux->xDelete ){
+        pAux->xDelete(pAux->pAux);
+      }
+      *pp = pAux->pNext;
+      sqlite3DbFree(db, pAux);
+    }else{
+      pp= &pAux->pNext;
+    }
+  }
+}
+
+/*
+** Free all memory associated with the Vdbe passed as the second argument,
+** except for object itself, which is preserved.
+**
+** The difference between this function and sqlite3VdbeDelete() is that
+** VdbeDelete() also unlinks the Vdbe from the list of VMs associated with
+** the database connection and frees the object itself.
+*/
+SQLITE_PRIVATE void sqlite3VdbeClearObject(sqlite3 *db, Vdbe *p){
+  SubProgram *pSub, *pNext;
+  int i;
+  assert( p->db==0 || p->db==db );
+  releaseMemArray(p->aColName, p->nResColumn*COLNAME_N);
+  for(pSub=p->pProgram; pSub; pSub=pNext){
+    pNext = pSub->pNext;
+    vdbeFreeOpArray(db, pSub->aOp, pSub->nOp);
+    sqlite3DbFree(db, pSub);
+  }
+  if( p->magic!=VDBE_MAGIC_INIT ){
+    releaseMemArray(p->aVar, p->nVar);
+    for(i=p->nzVar-1; i>=0; i--) sqlite3DbFree(db, p->azVar[i]);
+    sqlite3DbFree(db, p->azVar);
+    sqlite3DbFree(db, p->pFree);
+  }
+  vdbeFreeOpArray(db, p->aOp, p->nOp);
+  sqlite3DbFree(db, p->aColName);
+  sqlite3DbFree(db, p->zSql);
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+  for(i=0; i<p->nScan; i++){
+    sqlite3DbFree(db, p->aScan[i].zName);
+  }
+  sqlite3DbFree(db, p->aScan);
+#endif
+}
+
+/*
+** Delete an entire VDBE.
+*/
+SQLITE_PRIVATE void sqlite3VdbeDelete(Vdbe *p){
+  sqlite3 *db;
+
+  if( NEVER(p==0) ) return;
+  db = p->db;
+  assert( sqlite3_mutex_held(db->mutex) );
+  sqlite3VdbeClearObject(db, p);
+  if( p->pPrev ){
+    p->pPrev->pNext = p->pNext;
+  }else{
+    assert( db->pVdbe==p );
+    db->pVdbe = p->pNext;
+  }
+  if( p->pNext ){
+    p->pNext->pPrev = p->pPrev;
+  }
+  p->magic = VDBE_MAGIC_DEAD;
+  p->db = 0;
+  sqlite3DbFree(db, p);
+}
+
+/*
+** The cursor "p" has a pending seek operation that has not yet been
+** carried out.  Seek the cursor now.  If an error occurs, return
+** the appropriate error code.
+*/
+static int SQLITE_NOINLINE handleDeferredMoveto(VdbeCursor *p){
+  int res, rc;
+#ifdef SQLITE_TEST
+  extern int sqlite3_search_count;
+#endif
+  assert( p->deferredMoveto );
+  assert( p->isTable );
+  assert( p->eCurType==CURTYPE_BTREE );
+  rc = sqlite3BtreeMovetoUnpacked(p->uc.pCursor, 0, p->movetoTarget, 0, &res);
+  if( rc ) return rc;
+  if( res!=0 ) return SQLITE_CORRUPT_BKPT;
+#ifdef SQLITE_TEST
+  sqlite3_search_count++;
+#endif
+  p->deferredMoveto = 0;
+  p->cacheStatus = CACHE_STALE;
+  return SQLITE_OK;
+}
+
+/*
+** Something has moved cursor "p" out of place.  Maybe the row it was
+** pointed to was deleted out from under it.  Or maybe the btree was
+** rebalanced.  Whatever the cause, try to restore "p" to the place it
+** is supposed to be pointing.  If the row was deleted out from under the
+** cursor, set the cursor to point to a NULL row.
+*/
+static int SQLITE_NOINLINE handleMovedCursor(VdbeCursor *p){
+  int isDifferentRow, rc;
+  assert( p->eCurType==CURTYPE_BTREE );
+  assert( p->uc.pCursor!=0 );
+  assert( sqlite3BtreeCursorHasMoved(p->uc.pCursor) );
+  rc = sqlite3BtreeCursorRestore(p->uc.pCursor, &isDifferentRow);
+  p->cacheStatus = CACHE_STALE;
+  if( isDifferentRow ) p->nullRow = 1;
+  return rc;
+}
+
+/*
+** Check to ensure that the cursor is valid.  Restore the cursor
+** if need be.  Return any I/O error from the restore operation.
+*/
+SQLITE_PRIVATE int sqlite3VdbeCursorRestore(VdbeCursor *p){
+  assert( p->eCurType==CURTYPE_BTREE );
+  if( sqlite3BtreeCursorHasMoved(p->uc.pCursor) ){
+    return handleMovedCursor(p);
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Make sure the cursor p is ready to read or write the row to which it
+** was last positioned.  Return an error code if an OOM fault or I/O error
+** prevents us from positioning the cursor to its correct position.
+**
+** If a MoveTo operation is pending on the given cursor, then do that
+** MoveTo now.  If no move is pending, check to see if the row has been
+** deleted out from under the cursor and if it has, mark the row as
+** a NULL row.
+**
+** If the cursor is already pointing to the correct row and that row has
+** not been deleted out from under the cursor, then this routine is a no-op.
+*/
+SQLITE_PRIVATE int sqlite3VdbeCursorMoveto(VdbeCursor **pp, int *piCol){
+  VdbeCursor *p = *pp;
+  if( p->eCurType==CURTYPE_BTREE ){
+    if( p->deferredMoveto ){
+      int iMap;
+      if( p->aAltMap && (iMap = p->aAltMap[1+*piCol])>0 ){
+        *pp = p->pAltCursor;
+        *piCol = iMap - 1;
+        return SQLITE_OK;
+      }
+      return handleDeferredMoveto(p);
+    }
+    if( sqlite3BtreeCursorHasMoved(p->uc.pCursor) ){
+      return handleMovedCursor(p);
+    }
+  }
+  return SQLITE_OK;
+}
+
+/*
+** The following functions:
+**
+** sqlite3VdbeSerialType()
+** sqlite3VdbeSerialTypeLen()
+** sqlite3VdbeSerialLen()
+** sqlite3VdbeSerialPut()
+** sqlite3VdbeSerialGet()
+**
+** encapsulate the code that serializes values for storage in SQLite
+** data and index records. Each serialized value consists of a
+** 'serial-type' and a blob of data. The serial type is an 8-byte unsigned
+** integer, stored as a varint.
+**
+** In an SQLite index record, the serial type is stored directly before
+** the blob of data that it corresponds to. In a table record, all serial
+** types are stored at the start of the record, and the blobs of data at
+** the end. Hence these functions allow the caller to handle the
+** serial-type and data blob separately.
+**
+** The following table describes the various storage classes for data:
+**
+**   serial type        bytes of data      type
+**   --------------     ---------------    ---------------
+**      0                     0            NULL
+**      1                     1            signed integer
+**      2                     2            signed integer
+**      3                     3            signed integer
+**      4                     4            signed integer
+**      5                     6            signed integer
+**      6                     8            signed integer
+**      7                     8            IEEE float
+**      8                     0            Integer constant 0
+**      9                     0            Integer constant 1
+**     10,11                               reserved for expansion
+**    N>=12 and even       (N-12)/2        BLOB
+**    N>=13 and odd        (N-13)/2        text
+**
+** The 8 and 9 types were added in 3.3.0, file format 4.  Prior versions
+** of SQLite will not understand those serial types.
+*/
+
+/*
+** Return the serial-type for the value stored in pMem.
+*/
+SQLITE_PRIVATE u32 sqlite3VdbeSerialType(Mem *pMem, int file_format, u32 *pLen){
+  int flags = pMem->flags;
+  u32 n;
+
+  assert( pLen!=0 );
+  if( flags&MEM_Null ){
+    *pLen = 0;
+    return 0;
+  }
+  if( flags&MEM_Int ){
+    /* Figure out whether to use 1, 2, 4, 6 or 8 bytes. */
+#   define MAX_6BYTE ((((i64)0x00008000)<<32)-1)
+    i64 i = pMem->u.i;
+    u64 u;
+    if( i<0 ){
+      u = ~i;
+    }else{
+      u = i;
+    }
+    if( u<=127 ){
+      if( (i&1)==i && file_format>=4 ){
+        *pLen = 0;
+        return 8+(u32)u;
+      }else{
+        *pLen = 1;
+        return 1;
+      }
+    }
+    if( u<=32767 ){ *pLen = 2; return 2; }
+    if( u<=8388607 ){ *pLen = 3; return 3; }
+    if( u<=2147483647 ){ *pLen = 4; return 4; }
+    if( u<=MAX_6BYTE ){ *pLen = 6; return 5; }
+    *pLen = 8;
+    return 6;
+  }
+  if( flags&MEM_Real ){
+    *pLen = 8;
+    return 7;
+  }
+  assert( pMem->db->mallocFailed || flags&(MEM_Str|MEM_Blob) );
+  assert( pMem->n>=0 );
+  n = (u32)pMem->n;
+  if( flags & MEM_Zero ){
+    n += pMem->u.nZero;
+  }
+  *pLen = n;
+  return ((n*2) + 12 + ((flags&MEM_Str)!=0));
+}
+
+/*
+** The sizes for serial types less than 128
+*/
+static const u8 sqlite3SmallTypeSizes[] = {
+        /*  0   1   2   3   4   5   6   7   8   9 */   
+/*   0 */   0,  1,  2,  3,  4,  6,  8,  8,  0,  0,
+/*  10 */   0,  0,  0,  0,  1,  1,  2,  2,  3,  3,
+/*  20 */   4,  4,  5,  5,  6,  6,  7,  7,  8,  8,
+/*  30 */   9,  9, 10, 10, 11, 11, 12, 12, 13, 13,
+/*  40 */  14, 14, 15, 15, 16, 16, 17, 17, 18, 18,
+/*  50 */  19, 19, 20, 20, 21, 21, 22, 22, 23, 23,
+/*  60 */  24, 24, 25, 25, 26, 26, 27, 27, 28, 28,
+/*  70 */  29, 29, 30, 30, 31, 31, 32, 32, 33, 33,
+/*  80 */  34, 34, 35, 35, 36, 36, 37, 37, 38, 38,
+/*  90 */  39, 39, 40, 40, 41, 41, 42, 42, 43, 43,
+/* 100 */  44, 44, 45, 45, 46, 46, 47, 47, 48, 48,
+/* 110 */  49, 49, 50, 50, 51, 51, 52, 52, 53, 53,
+/* 120 */  54, 54, 55, 55, 56, 56, 57, 57
+};
+
+/*
+** Return the length of the data corresponding to the supplied serial-type.
+*/
+SQLITE_PRIVATE u32 sqlite3VdbeSerialTypeLen(u32 serial_type){
+  if( serial_type>=128 ){
+    return (serial_type-12)/2;
+  }else{
+    assert( serial_type<12 
+            || sqlite3SmallTypeSizes[serial_type]==(serial_type - 12)/2 );
+    return sqlite3SmallTypeSizes[serial_type];
+  }
+}
+SQLITE_PRIVATE u8 sqlite3VdbeOneByteSerialTypeLen(u8 serial_type){
+  assert( serial_type<128 );
+  return sqlite3SmallTypeSizes[serial_type];  
+}
+
+/*
+** If we are on an architecture with mixed-endian floating 
+** points (ex: ARM7) then swap the lower 4 bytes with the 
+** upper 4 bytes.  Return the result.
+**
+** For most architectures, this is a no-op.
+**
+** (later):  It is reported to me that the mixed-endian problem
+** on ARM7 is an issue with GCC, not with the ARM7 chip.  It seems
+** that early versions of GCC stored the two words of a 64-bit
+** float in the wrong order.  And that error has been propagated
+** ever since.  The blame is not necessarily with GCC, though.
+** GCC might have just copying the problem from a prior compiler.
+** I am also told that newer versions of GCC that follow a different
+** ABI get the byte order right.
+**
+** Developers using SQLite on an ARM7 should compile and run their
+** application using -DSQLITE_DEBUG=1 at least once.  With DEBUG
+** enabled, some asserts below will ensure that the byte order of
+** floating point values is correct.
+**
+** (2007-08-30)  Frank van Vugt has studied this problem closely
+** and has send his findings to the SQLite developers.  Frank
+** writes that some Linux kernels offer floating point hardware
+** emulation that uses only 32-bit mantissas instead of a full 
+** 48-bits as required by the IEEE standard.  (This is the
+** CONFIG_FPE_FASTFPE option.)  On such systems, floating point
+** byte swapping becomes very complicated.  To avoid problems,
+** the necessary byte swapping is carried out using a 64-bit integer
+** rather than a 64-bit float.  Frank assures us that the code here
+** works for him.  We, the developers, have no way to independently
+** verify this, but Frank seems to know what he is talking about
+** so we trust him.
+*/
+#ifdef SQLITE_MIXED_ENDIAN_64BIT_FLOAT
+static u64 floatSwap(u64 in){
+  union {
+    u64 r;
+    u32 i[2];
+  } u;
+  u32 t;
+
+  u.r = in;
+  t = u.i[0];
+  u.i[0] = u.i[1];
+  u.i[1] = t;
+  return u.r;
+}
+# define swapMixedEndianFloat(X)  X = floatSwap(X)
+#else
+# define swapMixedEndianFloat(X)
+#endif
+
+/*
+** Write the serialized data blob for the value stored in pMem into 
+** buf. It is assumed that the caller has allocated sufficient space.
+** Return the number of bytes written.
+**
+** nBuf is the amount of space left in buf[].  The caller is responsible
+** for allocating enough space to buf[] to hold the entire field, exclusive
+** of the pMem->u.nZero bytes for a MEM_Zero value.
+**
+** Return the number of bytes actually written into buf[].  The number
+** of bytes in the zero-filled tail is included in the return value only
+** if those bytes were zeroed in buf[].
+*/ 
+SQLITE_PRIVATE u32 sqlite3VdbeSerialPut(u8 *buf, Mem *pMem, u32 serial_type){
+  u32 len;
+
+  /* Integer and Real */
+  if( serial_type<=7 && serial_type>0 ){
+    u64 v;
+    u32 i;
+    if( serial_type==7 ){
+      assert( sizeof(v)==sizeof(pMem->u.r) );
+      memcpy(&v, &pMem->u.r, sizeof(v));
+      swapMixedEndianFloat(v);
+    }else{
+      v = pMem->u.i;
+    }
+    len = i = sqlite3SmallTypeSizes[serial_type];
+    assert( i>0 );
+    do{
+      buf[--i] = (u8)(v&0xFF);
+      v >>= 8;
+    }while( i );
+    return len;
+  }
+
+  /* String or blob */
+  if( serial_type>=12 ){
+    assert( pMem->n + ((pMem->flags & MEM_Zero)?pMem->u.nZero:0)
+             == (int)sqlite3VdbeSerialTypeLen(serial_type) );
+    len = pMem->n;
+    if( len>0 ) memcpy(buf, pMem->z, len);
+    return len;
+  }
+
+  /* NULL or constants 0 or 1 */
+  return 0;
+}
+
+/* Input "x" is a sequence of unsigned characters that represent a
+** big-endian integer.  Return the equivalent native integer
+*/
+#define ONE_BYTE_INT(x)    ((i8)(x)[0])
+#define TWO_BYTE_INT(x)    (256*(i8)((x)[0])|(x)[1])
+#define THREE_BYTE_INT(x)  (65536*(i8)((x)[0])|((x)[1]<<8)|(x)[2])
+#define FOUR_BYTE_UINT(x)  (((u32)(x)[0]<<24)|((x)[1]<<16)|((x)[2]<<8)|(x)[3])
+#define FOUR_BYTE_INT(x) (16777216*(i8)((x)[0])|((x)[1]<<16)|((x)[2]<<8)|(x)[3])
+
+/*
+** Deserialize the data blob pointed to by buf as serial type serial_type
+** and store the result in pMem.  Return the number of bytes read.
+**
+** This function is implemented as two separate routines for performance.
+** The few cases that require local variables are broken out into a separate
+** routine so that in most cases the overhead of moving the stack pointer
+** is avoided.
+*/ 
+static u32 SQLITE_NOINLINE serialGet(
+  const unsigned char *buf,     /* Buffer to deserialize from */
+  u32 serial_type,              /* Serial type to deserialize */
+  Mem *pMem                     /* Memory cell to write value into */
+){
+  u64 x = FOUR_BYTE_UINT(buf);
+  u32 y = FOUR_BYTE_UINT(buf+4);
+  x = (x<<32) + y;
+  if( serial_type==6 ){
+    /* EVIDENCE-OF: R-29851-52272 Value is a big-endian 64-bit
+    ** twos-complement integer. */
+    pMem->u.i = *(i64*)&x;
+    pMem->flags = MEM_Int;
+    testcase( pMem->u.i<0 );
+  }else{
+    /* EVIDENCE-OF: R-57343-49114 Value is a big-endian IEEE 754-2008 64-bit
+    ** floating point number. */
+#if !defined(NDEBUG) && !defined(SQLITE_OMIT_FLOATING_POINT)
+    /* Verify that integers and floating point values use the same
+    ** byte order.  Or, that if SQLITE_MIXED_ENDIAN_64BIT_FLOAT is
+    ** defined that 64-bit floating point values really are mixed
+    ** endian.
+    */
+    static const u64 t1 = ((u64)0x3ff00000)<<32;
+    static const double r1 = 1.0;
+    u64 t2 = t1;
+    swapMixedEndianFloat(t2);
+    assert( sizeof(r1)==sizeof(t2) && memcmp(&r1, &t2, sizeof(r1))==0 );
+#endif
+    assert( sizeof(x)==8 && sizeof(pMem->u.r)==8 );
+    swapMixedEndianFloat(x);
+    memcpy(&pMem->u.r, &x, sizeof(x));
+    pMem->flags = sqlite3IsNaN(pMem->u.r) ? MEM_Null : MEM_Real;
+  }
+  return 8;
+}
+SQLITE_PRIVATE u32 sqlite3VdbeSerialGet(
+  const unsigned char *buf,     /* Buffer to deserialize from */
+  u32 serial_type,              /* Serial type to deserialize */
+  Mem *pMem                     /* Memory cell to write value into */
+){
+  switch( serial_type ){
+    case 10:   /* Reserved for future use */
+    case 11:   /* Reserved for future use */
+    case 0: {  /* Null */
+      /* EVIDENCE-OF: R-24078-09375 Value is a NULL. */
+      pMem->flags = MEM_Null;
+      break;
+    }
+    case 1: {
+      /* EVIDENCE-OF: R-44885-25196 Value is an 8-bit twos-complement
+      ** integer. */
+      pMem->u.i = ONE_BYTE_INT(buf);
+      pMem->flags = MEM_Int;
+      testcase( pMem->u.i<0 );
+      return 1;
+    }
+    case 2: { /* 2-byte signed integer */
+      /* EVIDENCE-OF: R-49794-35026 Value is a big-endian 16-bit
+      ** twos-complement integer. */
+      pMem->u.i = TWO_BYTE_INT(buf);
+      pMem->flags = MEM_Int;
+      testcase( pMem->u.i<0 );
+      return 2;
+    }
+    case 3: { /* 3-byte signed integer */
+      /* EVIDENCE-OF: R-37839-54301 Value is a big-endian 24-bit
+      ** twos-complement integer. */
+      pMem->u.i = THREE_BYTE_INT(buf);
+      pMem->flags = MEM_Int;
+      testcase( pMem->u.i<0 );
+      return 3;
+    }
+    case 4: { /* 4-byte signed integer */
+      /* EVIDENCE-OF: R-01849-26079 Value is a big-endian 32-bit
+      ** twos-complement integer. */
+      pMem->u.i = FOUR_BYTE_INT(buf);
+#ifdef __HP_cc 
+      /* Work around a sign-extension bug in the HP compiler for HP/UX */
+      if( buf[0]&0x80 ) pMem->u.i |= 0xffffffff80000000LL;
+#endif
+      pMem->flags = MEM_Int;
+      testcase( pMem->u.i<0 );
+      return 4;
+    }
+    case 5: { /* 6-byte signed integer */
+      /* EVIDENCE-OF: R-50385-09674 Value is a big-endian 48-bit
+      ** twos-complement integer. */
+      pMem->u.i = FOUR_BYTE_UINT(buf+2) + (((i64)1)<<32)*TWO_BYTE_INT(buf);
+      pMem->flags = MEM_Int;
+      testcase( pMem->u.i<0 );
+      return 6;
+    }
+    case 6:   /* 8-byte signed integer */
+    case 7: { /* IEEE floating point */
+      /* These use local variables, so do them in a separate routine
+      ** to avoid having to move the frame pointer in the common case */
+      return serialGet(buf,serial_type,pMem);
+    }
+    case 8:    /* Integer 0 */
+    case 9: {  /* Integer 1 */
+      /* EVIDENCE-OF: R-12976-22893 Value is the integer 0. */
+      /* EVIDENCE-OF: R-18143-12121 Value is the integer 1. */
+      pMem->u.i = serial_type-8;
+      pMem->flags = MEM_Int;
+      return 0;
+    }
+    default: {
+      /* EVIDENCE-OF: R-14606-31564 Value is a BLOB that is (N-12)/2 bytes in
+      ** length.
+      ** EVIDENCE-OF: R-28401-00140 Value is a string in the text encoding and
+      ** (N-13)/2 bytes in length. */
+      static const u16 aFlag[] = { MEM_Blob|MEM_Ephem, MEM_Str|MEM_Ephem };
+      pMem->z = (char *)buf;
+      pMem->n = (serial_type-12)/2;
+      pMem->flags = aFlag[serial_type&1];
+      return pMem->n;
+    }
+  }
+  return 0;
+}
+/*
+** This routine is used to allocate sufficient space for an UnpackedRecord
+** structure large enough to be used with sqlite3VdbeRecordUnpack() if
+** the first argument is a pointer to KeyInfo structure pKeyInfo.
+**
+** The space is either allocated using sqlite3DbMallocRaw() or from within
+** the unaligned buffer passed via the second and third arguments (presumably
+** stack space). If the former, then *ppFree is set to a pointer that should
+** be eventually freed by the caller using sqlite3DbFree(). Or, if the 
+** allocation comes from the pSpace/szSpace buffer, *ppFree is set to NULL
+** before returning.
+**
+** If an OOM error occurs, NULL is returned.
+*/
+SQLITE_PRIVATE UnpackedRecord *sqlite3VdbeAllocUnpackedRecord(
+  KeyInfo *pKeyInfo,              /* Description of the record */
+  char *pSpace,                   /* Unaligned space available */
+  int szSpace,                    /* Size of pSpace[] in bytes */
+  char **ppFree                   /* OUT: Caller should free this pointer */
+){
+  UnpackedRecord *p;              /* Unpacked record to return */
+  int nOff;                       /* Increment pSpace by nOff to align it */
+  int nByte;                      /* Number of bytes required for *p */
+
+  /* We want to shift the pointer pSpace up such that it is 8-byte aligned.
+  ** Thus, we need to calculate a value, nOff, between 0 and 7, to shift 
+  ** it by.  If pSpace is already 8-byte aligned, nOff should be zero.
+  */
+  nOff = (8 - (SQLITE_PTR_TO_INT(pSpace) & 7)) & 7;
+  nByte = ROUND8(sizeof(UnpackedRecord)) + sizeof(Mem)*(pKeyInfo->nField+1);
+  if( nByte>szSpace+nOff ){
+    p = (UnpackedRecord *)sqlite3DbMallocRaw(pKeyInfo->db, nByte);
+    *ppFree = (char *)p;
+    if( !p ) return 0;
+  }else{
+    p = (UnpackedRecord*)&pSpace[nOff];
+    *ppFree = 0;
+  }
+
+  p->aMem = (Mem*)&((char*)p)[ROUND8(sizeof(UnpackedRecord))];
+  assert( pKeyInfo->aSortOrder!=0 );
+  p->pKeyInfo = pKeyInfo;
+  p->nField = pKeyInfo->nField + 1;
+  return p;
+}
+
+/*
+** Given the nKey-byte encoding of a record in pKey[], populate the 
+** UnpackedRecord structure indicated by the fourth argument with the
+** contents of the decoded record.
+*/ 
+SQLITE_PRIVATE void sqlite3VdbeRecordUnpack(
+  KeyInfo *pKeyInfo,     /* Information about the record format */
+  int nKey,              /* Size of the binary record */
+  const void *pKey,      /* The binary record */
+  UnpackedRecord *p      /* Populate this structure before returning. */
+){
+  const unsigned char *aKey = (const unsigned char *)pKey;
+  int d; 
+  u32 idx;                        /* Offset in aKey[] to read from */
+  u16 u;                          /* Unsigned loop counter */
+  u32 szHdr;
+  Mem *pMem = p->aMem;
+
+  p->default_rc = 0;
+  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
+  idx = getVarint32(aKey, szHdr);
+  d = szHdr;
+  u = 0;
+  while( idx<szHdr && d<=nKey ){
+    u32 serial_type;
+
+    idx += getVarint32(&aKey[idx], serial_type);
+    pMem->enc = pKeyInfo->enc;
+    pMem->db = pKeyInfo->db;
+    /* pMem->flags = 0; // sqlite3VdbeSerialGet() will set this for us */
+    pMem->szMalloc = 0;
+    pMem->z = 0;
+    d += sqlite3VdbeSerialGet(&aKey[d], serial_type, pMem);
+    pMem++;
+    if( (++u)>=p->nField ) break;
+  }
+  assert( u<=pKeyInfo->nField + 1 );
+  p->nField = u;
+}
+
+#if SQLITE_DEBUG
+/*
+** This function compares two index or table record keys in the same way
+** as the sqlite3VdbeRecordCompare() routine. Unlike VdbeRecordCompare(),
+** this function deserializes and compares values using the
+** sqlite3VdbeSerialGet() and sqlite3MemCompare() functions. It is used
+** in assert() statements to ensure that the optimized code in
+** sqlite3VdbeRecordCompare() returns results with these two primitives.
+**
+** Return true if the result of comparison is equivalent to desiredResult.
+** Return false if there is a disagreement.
+*/
+static int vdbeRecordCompareDebug(
+  int nKey1, const void *pKey1, /* Left key */
+  const UnpackedRecord *pPKey2, /* Right key */
+  int desiredResult             /* Correct answer */
+){
+  u32 d1;            /* Offset into aKey[] of next data element */
+  u32 idx1;          /* Offset into aKey[] of next header element */
+  u32 szHdr1;        /* Number of bytes in header */
+  int i = 0;
+  int rc = 0;
+  const unsigned char *aKey1 = (const unsigned char *)pKey1;
+  KeyInfo *pKeyInfo;
+  Mem mem1;
+
+  pKeyInfo = pPKey2->pKeyInfo;
+  if( pKeyInfo->db==0 ) return 1;
+  mem1.enc = pKeyInfo->enc;
+  mem1.db = pKeyInfo->db;
+  /* mem1.flags = 0;  // Will be initialized by sqlite3VdbeSerialGet() */
+  VVA_ONLY( mem1.szMalloc = 0; ) /* Only needed by assert() statements */
+
+  /* Compilers may complain that mem1.u.i is potentially uninitialized.
+  ** We could initialize it, as shown here, to silence those complaints.
+  ** But in fact, mem1.u.i will never actually be used uninitialized, and doing 
+  ** the unnecessary initialization has a measurable negative performance
+  ** impact, since this routine is a very high runner.  And so, we choose
+  ** to ignore the compiler warnings and leave this variable uninitialized.
+  */
+  /*  mem1.u.i = 0;  // not needed, here to silence compiler warning */
+  
+  idx1 = getVarint32(aKey1, szHdr1);
+  if( szHdr1>98307 ) return SQLITE_CORRUPT;
+  d1 = szHdr1;
+  assert( pKeyInfo->nField+pKeyInfo->nXField>=pPKey2->nField || CORRUPT_DB );
+  assert( pKeyInfo->aSortOrder!=0 );
+  assert( pKeyInfo->nField>0 );
+  assert( idx1<=szHdr1 || CORRUPT_DB );
+  do{
+    u32 serial_type1;
+
+    /* Read the serial types for the next element in each key. */
+    idx1 += getVarint32( aKey1+idx1, serial_type1 );
+
+    /* Verify that there is enough key space remaining to avoid
+    ** a buffer overread.  The "d1+serial_type1+2" subexpression will
+    ** always be greater than or equal to the amount of required key space.
+    ** Use that approximation to avoid the more expensive call to
+    ** sqlite3VdbeSerialTypeLen() in the common case.
+    */
+    if( d1+serial_type1+2>(u32)nKey1
+     && d1+sqlite3VdbeSerialTypeLen(serial_type1)>(u32)nKey1 
+    ){
+      break;
+    }
+
+    /* Extract the values to be compared.
+    */
+    d1 += sqlite3VdbeSerialGet(&aKey1[d1], serial_type1, &mem1);
+
+    /* Do the comparison
+    */
+    rc = sqlite3MemCompare(&mem1, &pPKey2->aMem[i], pKeyInfo->aColl[i]);
+    if( rc!=0 ){
+      assert( mem1.szMalloc==0 );  /* See comment below */
+      if( pKeyInfo->aSortOrder[i] ){
+        rc = -rc;  /* Invert the result for DESC sort order. */
+      }
+      goto debugCompareEnd;
+    }
+    i++;
+  }while( idx1<szHdr1 && i<pPKey2->nField );
+
+  /* No memory allocation is ever used on mem1.  Prove this using
+  ** the following assert().  If the assert() fails, it indicates a
+  ** memory leak and a need to call sqlite3VdbeMemRelease(&mem1).
+  */
+  assert( mem1.szMalloc==0 );
+
+  /* rc==0 here means that one of the keys ran out of fields and
+  ** all the fields up to that point were equal. Return the default_rc
+  ** value.  */
+  rc = pPKey2->default_rc;
+
+debugCompareEnd:
+  if( desiredResult==0 && rc==0 ) return 1;
+  if( desiredResult<0 && rc<0 ) return 1;
+  if( desiredResult>0 && rc>0 ) return 1;
+  if( CORRUPT_DB ) return 1;
+  if( pKeyInfo->db->mallocFailed ) return 1;
+  return 0;
+}
+#endif
+
+#if SQLITE_DEBUG
+/*
+** Count the number of fields (a.k.a. columns) in the record given by
+** pKey,nKey.  The verify that this count is less than or equal to the
+** limit given by pKeyInfo->nField + pKeyInfo->nXField.
+**
+** If this constraint is not satisfied, it means that the high-speed
+** vdbeRecordCompareInt() and vdbeRecordCompareString() routines will
+** not work correctly.  If this assert() ever fires, it probably means
+** that the KeyInfo.nField or KeyInfo.nXField values were computed
+** incorrectly.
+*/
+static void vdbeAssertFieldCountWithinLimits(
+  int nKey, const void *pKey,   /* The record to verify */ 
+  const KeyInfo *pKeyInfo       /* Compare size with this KeyInfo */
+){
+  int nField = 0;
+  u32 szHdr;
+  u32 idx;
+  u32 notUsed;
+  const unsigned char *aKey = (const unsigned char*)pKey;
+
+  if( CORRUPT_DB ) return;
+  idx = getVarint32(aKey, szHdr);
+  assert( nKey>=0 );
+  assert( szHdr<=(u32)nKey );
+  while( idx<szHdr ){
+    idx += getVarint32(aKey+idx, notUsed);
+    nField++;
+  }
+  assert( nField <= pKeyInfo->nField+pKeyInfo->nXField );
+}
+#else
+# define vdbeAssertFieldCountWithinLimits(A,B,C)
+#endif
+
+/*
+** Both *pMem1 and *pMem2 contain string values. Compare the two values
+** using the collation sequence pColl. As usual, return a negative , zero
+** or positive value if *pMem1 is less than, equal to or greater than 
+** *pMem2, respectively. Similar in spirit to "rc = (*pMem1) - (*pMem2);".
+*/
+static int vdbeCompareMemString(
+  const Mem *pMem1,
+  const Mem *pMem2,
+  const CollSeq *pColl,
+  u8 *prcErr                      /* If an OOM occurs, set to SQLITE_NOMEM */
+){
+  if( pMem1->enc==pColl->enc ){
+    /* The strings are already in the correct encoding.  Call the
+     ** comparison function directly */
+    return pColl->xCmp(pColl->pUser,pMem1->n,pMem1->z,pMem2->n,pMem2->z);
+  }else{
+    int rc;
+    const void *v1, *v2;
+    int n1, n2;
+    Mem c1;
+    Mem c2;
+    sqlite3VdbeMemInit(&c1, pMem1->db, MEM_Null);
+    sqlite3VdbeMemInit(&c2, pMem1->db, MEM_Null);
+    sqlite3VdbeMemShallowCopy(&c1, pMem1, MEM_Ephem);
+    sqlite3VdbeMemShallowCopy(&c2, pMem2, MEM_Ephem);
+    v1 = sqlite3ValueText((sqlite3_value*)&c1, pColl->enc);
+    n1 = v1==0 ? 0 : c1.n;
+    v2 = sqlite3ValueText((sqlite3_value*)&c2, pColl->enc);
+    n2 = v2==0 ? 0 : c2.n;
+    rc = pColl->xCmp(pColl->pUser, n1, v1, n2, v2);
+    if( (v1==0 || v2==0) && prcErr ) *prcErr = SQLITE_NOMEM_BKPT;
+    sqlite3VdbeMemRelease(&c1);
+    sqlite3VdbeMemRelease(&c2);
+    return rc;
+  }
+}
+
+/*
+** The input pBlob is guaranteed to be a Blob that is not marked
+** with MEM_Zero.  Return true if it could be a zero-blob.
+*/
+static int isAllZero(const char *z, int n){
+  int i;
+  for(i=0; i<n; i++){
+    if( z[i] ) return 0;
+  }
+  return 1;
+}
+
+/*
+** Compare two blobs.  Return negative, zero, or positive if the first
+** is less than, equal to, or greater than the second, respectively.
+** If one blob is a prefix of the other, then the shorter is the lessor.
+*/
+static SQLITE_NOINLINE int sqlite3BlobCompare(const Mem *pB1, const Mem *pB2){
+  int c;
+  int n1 = pB1->n;
+  int n2 = pB2->n;
+
+  /* It is possible to have a Blob value that has some non-zero content
+  ** followed by zero content.  But that only comes up for Blobs formed
+  ** by the OP_MakeRecord opcode, and such Blobs never get passed into
+  ** sqlite3MemCompare(). */
+  assert( (pB1->flags & MEM_Zero)==0 || n1==0 );
+  assert( (pB2->flags & MEM_Zero)==0 || n2==0 );
+
+  if( (pB1->flags|pB2->flags) & MEM_Zero ){
+    if( pB1->flags & pB2->flags & MEM_Zero ){
+      return pB1->u.nZero - pB2->u.nZero;
+    }else if( pB1->flags & MEM_Zero ){
+      if( !isAllZero(pB2->z, pB2->n) ) return -1;
+      return pB1->u.nZero - n2;
+    }else{
+      if( !isAllZero(pB1->z, pB1->n) ) return +1;
+      return n1 - pB2->u.nZero;
+    }
+  }
+  c = memcmp(pB1->z, pB2->z, n1>n2 ? n2 : n1);
+  if( c ) return c;
+  return n1 - n2;
+}
+
+/*
+** Do a comparison between a 64-bit signed integer and a 64-bit floating-point
+** number.  Return negative, zero, or positive if the first (i64) is less than,
+** equal to, or greater than the second (double).
+*/
+static int sqlite3IntFloatCompare(i64 i, double r){
+  if( sizeof(LONGDOUBLE_TYPE)>8 ){
+    LONGDOUBLE_TYPE x = (LONGDOUBLE_TYPE)i;
+    if( x<r ) return -1;
+    if( x>r ) return +1;
+    return 0;
+  }else{
+    i64 y;
+    double s;
+    if( r<-9223372036854775808.0 ) return +1;
+    if( r>9223372036854775807.0 ) return -1;
+    y = (i64)r;
+    if( i<y ) return -1;
+    if( i>y ){
+      if( y==SMALLEST_INT64 && r>0.0 ) return -1;
+      return +1;
+    }
+    s = (double)i;
+    if( s<r ) return -1;
+    if( s>r ) return +1;
+    return 0;
+  }
+}
+
+/*
+** Compare the values contained by the two memory cells, returning
+** negative, zero or positive if pMem1 is less than, equal to, or greater
+** than pMem2. Sorting order is NULL's first, followed by numbers (integers
+** and reals) sorted numerically, followed by text ordered by the collating
+** sequence pColl and finally blob's ordered by memcmp().
+**
+** Two NULL values are considered equal by this function.
+*/
+SQLITE_PRIVATE int sqlite3MemCompare(const Mem *pMem1, const Mem *pMem2, const CollSeq *pColl){
+  int f1, f2;
+  int combined_flags;
+
+  f1 = pMem1->flags;
+  f2 = pMem2->flags;
+  combined_flags = f1|f2;
+  assert( (combined_flags & MEM_RowSet)==0 );
+ 
+  /* If one value is NULL, it is less than the other. If both values
+  ** are NULL, return 0.
+  */
+  if( combined_flags&MEM_Null ){
+    return (f2&MEM_Null) - (f1&MEM_Null);
+  }
+
+  /* At least one of the two values is a number
+  */
+  if( combined_flags&(MEM_Int|MEM_Real) ){
+    if( (f1 & f2 & MEM_Int)!=0 ){
+      if( pMem1->u.i < pMem2->u.i ) return -1;
+      if( pMem1->u.i > pMem2->u.i ) return +1;
+      return 0;
+    }
+    if( (f1 & f2 & MEM_Real)!=0 ){
+      if( pMem1->u.r < pMem2->u.r ) return -1;
+      if( pMem1->u.r > pMem2->u.r ) return +1;
+      return 0;
+    }
+    if( (f1&MEM_Int)!=0 ){
+      if( (f2&MEM_Real)!=0 ){
+        return sqlite3IntFloatCompare(pMem1->u.i, pMem2->u.r);
+      }else{
+        return -1;
+      }
+    }
+    if( (f1&MEM_Real)!=0 ){
+      if( (f2&MEM_Int)!=0 ){
+        return -sqlite3IntFloatCompare(pMem2->u.i, pMem1->u.r);
+      }else{
+        return -1;
+      }
+    }
+    return +1;
+  }
+
+  /* If one value is a string and the other is a blob, the string is less.
+  ** If both are strings, compare using the collating functions.
+  */
+  if( combined_flags&MEM_Str ){
+    if( (f1 & MEM_Str)==0 ){
+      return 1;
+    }
+    if( (f2 & MEM_Str)==0 ){
+      return -1;
+    }
+
+    assert( pMem1->enc==pMem2->enc || pMem1->db->mallocFailed );
+    assert( pMem1->enc==SQLITE_UTF8 || 
+            pMem1->enc==SQLITE_UTF16LE || pMem1->enc==SQLITE_UTF16BE );
+
+    /* The collation sequence must be defined at this point, even if
+    ** the user deletes the collation sequence after the vdbe program is
+    ** compiled (this was not always the case).
+    */
+    assert( !pColl || pColl->xCmp );
+
+    if( pColl ){
+      return vdbeCompareMemString(pMem1, pMem2, pColl, 0);
+    }
+    /* If a NULL pointer was passed as the collate function, fall through
+    ** to the blob case and use memcmp().  */
+  }
+ 
+  /* Both values must be blobs.  Compare using memcmp().  */
+  return sqlite3BlobCompare(pMem1, pMem2);
+}
+
+
+/*
+** The first argument passed to this function is a serial-type that
+** corresponds to an integer - all values between 1 and 9 inclusive 
+** except 7. The second points to a buffer containing an integer value
+** serialized according to serial_type. This function deserializes
+** and returns the value.
+*/
+static i64 vdbeRecordDecodeInt(u32 serial_type, const u8 *aKey){
+  u32 y;
+  assert( CORRUPT_DB || (serial_type>=1 && serial_type<=9 && serial_type!=7) );
+  switch( serial_type ){
+    case 0:
+    case 1:
+      testcase( aKey[0]&0x80 );
+      return ONE_BYTE_INT(aKey);
+    case 2:
+      testcase( aKey[0]&0x80 );
+      return TWO_BYTE_INT(aKey);
+    case 3:
+      testcase( aKey[0]&0x80 );
+      return THREE_BYTE_INT(aKey);
+    case 4: {
+      testcase( aKey[0]&0x80 );
+      y = FOUR_BYTE_UINT(aKey);
+      return (i64)*(int*)&y;
+    }
+    case 5: {
+      testcase( aKey[0]&0x80 );
+      return FOUR_BYTE_UINT(aKey+2) + (((i64)1)<<32)*TWO_BYTE_INT(aKey);
+    }
+    case 6: {
+      u64 x = FOUR_BYTE_UINT(aKey);
+      testcase( aKey[0]&0x80 );
+      x = (x<<32) | FOUR_BYTE_UINT(aKey+4);
+      return (i64)*(i64*)&x;
+    }
+  }
+
+  return (serial_type - 8);
+}
+
+/*
+** This function compares the two table rows or index records
+** specified by {nKey1, pKey1} and pPKey2.  It returns a negative, zero
+** or positive integer if key1 is less than, equal to or 
+** greater than key2.  The {nKey1, pKey1} key must be a blob
+** created by the OP_MakeRecord opcode of the VDBE.  The pPKey2
+** key must be a parsed key such as obtained from
+** sqlite3VdbeParseRecord.
+**
+** If argument bSkip is non-zero, it is assumed that the caller has already
+** determined that the first fields of the keys are equal.
+**
+** Key1 and Key2 do not have to contain the same number of fields. If all 
+** fields that appear in both keys are equal, then pPKey2->default_rc is 
+** returned.
+**
+** If database corruption is discovered, set pPKey2->errCode to 
+** SQLITE_CORRUPT and return 0. If an OOM error is encountered, 
+** pPKey2->errCode is set to SQLITE_NOMEM and, if it is not NULL, the
+** malloc-failed flag set on database handle (pPKey2->pKeyInfo->db).
+*/
+SQLITE_PRIVATE int sqlite3VdbeRecordCompareWithSkip(
+  int nKey1, const void *pKey1,   /* Left key */
+  UnpackedRecord *pPKey2,         /* Right key */
+  int bSkip                       /* If true, skip the first field */
+){
+  u32 d1;                         /* Offset into aKey[] of next data element */
+  int i;                          /* Index of next field to compare */
+  u32 szHdr1;                     /* Size of record header in bytes */
+  u32 idx1;                       /* Offset of first type in header */
+  int rc = 0;                     /* Return value */
+  Mem *pRhs = pPKey2->aMem;       /* Next field of pPKey2 to compare */
+  KeyInfo *pKeyInfo = pPKey2->pKeyInfo;
+  const unsigned char *aKey1 = (const unsigned char *)pKey1;
+  Mem mem1;
+
+  /* If bSkip is true, then the caller has already determined that the first
+  ** two elements in the keys are equal. Fix the various stack variables so
+  ** that this routine begins comparing at the second field. */
+  if( bSkip ){
+    u32 s1;
+    idx1 = 1 + getVarint32(&aKey1[1], s1);
+    szHdr1 = aKey1[0];
+    d1 = szHdr1 + sqlite3VdbeSerialTypeLen(s1);
+    i = 1;
+    pRhs++;
+  }else{
+    idx1 = getVarint32(aKey1, szHdr1);
+    d1 = szHdr1;
+    if( d1>(unsigned)nKey1 ){ 
+      pPKey2->errCode = (u8)SQLITE_CORRUPT_BKPT;
+      return 0;  /* Corruption */
+    }
+    i = 0;
+  }
+
+  VVA_ONLY( mem1.szMalloc = 0; ) /* Only needed by assert() statements */
+  assert( pPKey2->pKeyInfo->nField+pPKey2->pKeyInfo->nXField>=pPKey2->nField 
+       || CORRUPT_DB );
+  assert( pPKey2->pKeyInfo->aSortOrder!=0 );
+  assert( pPKey2->pKeyInfo->nField>0 );
+  assert( idx1<=szHdr1 || CORRUPT_DB );
+  do{
+    u32 serial_type;
+
+    /* RHS is an integer */
+    if( pRhs->flags & MEM_Int ){
+      serial_type = aKey1[idx1];
+      testcase( serial_type==12 );
+      if( serial_type>=10 ){
+        rc = +1;
+      }else if( serial_type==0 ){
+        rc = -1;
+      }else if( serial_type==7 ){
+        sqlite3VdbeSerialGet(&aKey1[d1], serial_type, &mem1);
+        rc = -sqlite3IntFloatCompare(pRhs->u.i, mem1.u.r);
+      }else{
+        i64 lhs = vdbeRecordDecodeInt(serial_type, &aKey1[d1]);
+        i64 rhs = pRhs->u.i;
+        if( lhs<rhs ){
+          rc = -1;
+        }else if( lhs>rhs ){
+          rc = +1;
+        }
+      }
+    }
+
+    /* RHS is real */
+    else if( pRhs->flags & MEM_Real ){
+      serial_type = aKey1[idx1];
+      if( serial_type>=10 ){
+        /* Serial types 12 or greater are strings and blobs (greater than
+        ** numbers). Types 10 and 11 are currently "reserved for future 
+        ** use", so it doesn't really matter what the results of comparing
+        ** them to numberic values are.  */
+        rc = +1;
+      }else if( serial_type==0 ){
+        rc = -1;
+      }else{
+        sqlite3VdbeSerialGet(&aKey1[d1], serial_type, &mem1);
+        if( serial_type==7 ){
+          if( mem1.u.r<pRhs->u.r ){
+            rc = -1;
+          }else if( mem1.u.r>pRhs->u.r ){
+            rc = +1;
+          }
+        }else{
+          rc = sqlite3IntFloatCompare(mem1.u.i, pRhs->u.r);
+        }
+      }
+    }
+
+    /* RHS is a string */
+    else if( pRhs->flags & MEM_Str ){
+      getVarint32(&aKey1[idx1], serial_type);
+      testcase( serial_type==12 );
+      if( serial_type<12 ){
+        rc = -1;
+      }else if( !(serial_type & 0x01) ){
+        rc = +1;
+      }else{
+        mem1.n = (serial_type - 12) / 2;
+        testcase( (d1+mem1.n)==(unsigned)nKey1 );
+        testcase( (d1+mem1.n+1)==(unsigned)nKey1 );
+        if( (d1+mem1.n) > (unsigned)nKey1 ){
+          pPKey2->errCode = (u8)SQLITE_CORRUPT_BKPT;
+          return 0;                /* Corruption */
+        }else if( pKeyInfo->aColl[i] ){
+          mem1.enc = pKeyInfo->enc;
+          mem1.db = pKeyInfo->db;
+          mem1.flags = MEM_Str;
+          mem1.z = (char*)&aKey1[d1];
+          rc = vdbeCompareMemString(
+              &mem1, pRhs, pKeyInfo->aColl[i], &pPKey2->errCode
+          );
+        }else{
+          int nCmp = MIN(mem1.n, pRhs->n);
+          rc = memcmp(&aKey1[d1], pRhs->z, nCmp);
+          if( rc==0 ) rc = mem1.n - pRhs->n; 
+        }
+      }
+    }
+
+    /* RHS is a blob */
+    else if( pRhs->flags & MEM_Blob ){
+      assert( (pRhs->flags & MEM_Zero)==0 || pRhs->n==0 );
+      getVarint32(&aKey1[idx1], serial_type);
+      testcase( serial_type==12 );
+      if( serial_type<12 || (serial_type & 0x01) ){
+        rc = -1;
+      }else{
+        int nStr = (serial_type - 12) / 2;
+        testcase( (d1+nStr)==(unsigned)nKey1 );
+        testcase( (d1+nStr+1)==(unsigned)nKey1 );
+        if( (d1+nStr) > (unsigned)nKey1 ){
+          pPKey2->errCode = (u8)SQLITE_CORRUPT_BKPT;
+          return 0;                /* Corruption */
+        }else if( pRhs->flags & MEM_Zero ){
+          if( !isAllZero((const char*)&aKey1[d1],nStr) ){
+            rc = 1;
+          }else{
+            rc = nStr - pRhs->u.nZero;
+          }
+        }else{
+          int nCmp = MIN(nStr, pRhs->n);
+          rc = memcmp(&aKey1[d1], pRhs->z, nCmp);
+          if( rc==0 ) rc = nStr - pRhs->n;
+        }
+      }
+    }
+
+    /* RHS is null */
+    else{
+      serial_type = aKey1[idx1];
+      rc = (serial_type!=0);
+    }
+
+    if( rc!=0 ){
+      if( pKeyInfo->aSortOrder[i] ){
+        rc = -rc;
+      }
+      assert( vdbeRecordCompareDebug(nKey1, pKey1, pPKey2, rc) );
+      assert( mem1.szMalloc==0 );  /* See comment below */
+      return rc;
+    }
+
+    i++;
+    pRhs++;
+    d1 += sqlite3VdbeSerialTypeLen(serial_type);
+    idx1 += sqlite3VarintLen(serial_type);
+  }while( idx1<(unsigned)szHdr1 && i<pPKey2->nField && d1<=(unsigned)nKey1 );
+
+  /* No memory allocation is ever used on mem1.  Prove this using
+  ** the following assert().  If the assert() fails, it indicates a
+  ** memory leak and a need to call sqlite3VdbeMemRelease(&mem1).  */
+  assert( mem1.szMalloc==0 );
+
+  /* rc==0 here means that one or both of the keys ran out of fields and
+  ** all the fields up to that point were equal. Return the default_rc
+  ** value.  */
+  assert( CORRUPT_DB 
+       || vdbeRecordCompareDebug(nKey1, pKey1, pPKey2, pPKey2->default_rc) 
+       || pKeyInfo->db->mallocFailed
+  );
+  pPKey2->eqSeen = 1;
+  return pPKey2->default_rc;
+}
+SQLITE_PRIVATE int sqlite3VdbeRecordCompare(
+  int nKey1, const void *pKey1,   /* Left key */
+  UnpackedRecord *pPKey2          /* Right key */
+){
+  return sqlite3VdbeRecordCompareWithSkip(nKey1, pKey1, pPKey2, 0);
+}
+
+
+/*
+** This function is an optimized version of sqlite3VdbeRecordCompare() 
+** that (a) the first field of pPKey2 is an integer, and (b) the 
+** size-of-header varint at the start of (pKey1/nKey1) fits in a single
+** byte (i.e. is less than 128).
+**
+** To avoid concerns about buffer overreads, this routine is only used
+** on schemas where the maximum valid header size is 63 bytes or less.
+*/
+static int vdbeRecordCompareInt(
+  int nKey1, const void *pKey1, /* Left key */
+  UnpackedRecord *pPKey2        /* Right key */
+){
+  const u8 *aKey = &((const u8*)pKey1)[*(const u8*)pKey1 & 0x3F];
+  int serial_type = ((const u8*)pKey1)[1];
+  int res;
+  u32 y;
+  u64 x;
+  i64 v;
+  i64 lhs;
+
+  vdbeAssertFieldCountWithinLimits(nKey1, pKey1, pPKey2->pKeyInfo);
+  assert( (*(u8*)pKey1)<=0x3F || CORRUPT_DB );
+  switch( serial_type ){
+    case 1: { /* 1-byte signed integer */
+      lhs = ONE_BYTE_INT(aKey);
+      testcase( lhs<0 );
+      break;
+    }
+    case 2: { /* 2-byte signed integer */
+      lhs = TWO_BYTE_INT(aKey);
+      testcase( lhs<0 );
+      break;
+    }
+    case 3: { /* 3-byte signed integer */
+      lhs = THREE_BYTE_INT(aKey);
+      testcase( lhs<0 );
+      break;
+    }
+    case 4: { /* 4-byte signed integer */
+      y = FOUR_BYTE_UINT(aKey);
+      lhs = (i64)*(int*)&y;
+      testcase( lhs<0 );
+      break;
+    }
+    case 5: { /* 6-byte signed integer */
+      lhs = FOUR_BYTE_UINT(aKey+2) + (((i64)1)<<32)*TWO_BYTE_INT(aKey);
+      testcase( lhs<0 );
+      break;
+    }
+    case 6: { /* 8-byte signed integer */
+      x = FOUR_BYTE_UINT(aKey);
+      x = (x<<32) | FOUR_BYTE_UINT(aKey+4);
+      lhs = *(i64*)&x;
+      testcase( lhs<0 );
+      break;
+    }
+    case 8: 
+      lhs = 0;
+      break;
+    case 9:
+      lhs = 1;
+      break;
+
+    /* This case could be removed without changing the results of running
+    ** this code. Including it causes gcc to generate a faster switch 
+    ** statement (since the range of switch targets now starts at zero and
+    ** is contiguous) but does not cause any duplicate code to be generated
+    ** (as gcc is clever enough to combine the two like cases). Other 
+    ** compilers might be similar.  */ 
+    case 0: case 7:
+      return sqlite3VdbeRecordCompare(nKey1, pKey1, pPKey2);
+
+    default:
+      return sqlite3VdbeRecordCompare(nKey1, pKey1, pPKey2);
+  }
+
+  v = pPKey2->aMem[0].u.i;
+  if( v>lhs ){
+    res = pPKey2->r1;
+  }else if( v<lhs ){
+    res = pPKey2->r2;
+  }else if( pPKey2->nField>1 ){
+    /* The first fields of the two keys are equal. Compare the trailing 
+    ** fields.  */
+    res = sqlite3VdbeRecordCompareWithSkip(nKey1, pKey1, pPKey2, 1);
+  }else{
+    /* The first fields of the two keys are equal and there are no trailing
+    ** fields. Return pPKey2->default_rc in this case. */
+    res = pPKey2->default_rc;
+    pPKey2->eqSeen = 1;
+  }
+
+  assert( vdbeRecordCompareDebug(nKey1, pKey1, pPKey2, res) );
+  return res;
+}
+
+/*
+** This function is an optimized version of sqlite3VdbeRecordCompare() 
+** that (a) the first field of pPKey2 is a string, that (b) the first field
+** uses the collation sequence BINARY and (c) that the size-of-header varint 
+** at the start of (pKey1/nKey1) fits in a single byte.
+*/
+static int vdbeRecordCompareString(
+  int nKey1, const void *pKey1, /* Left key */
+  UnpackedRecord *pPKey2        /* Right key */
+){
+  const u8 *aKey1 = (const u8*)pKey1;
+  int serial_type;
+  int res;
+
+  assert( pPKey2->aMem[0].flags & MEM_Str );
+  vdbeAssertFieldCountWithinLimits(nKey1, pKey1, pPKey2->pKeyInfo);
+  getVarint32(&aKey1[1], serial_type);
+  if( serial_type<12 ){
+    res = pPKey2->r1;      /* (pKey1/nKey1) is a number or a null */
+  }else if( !(serial_type & 0x01) ){ 
+    res = pPKey2->r2;      /* (pKey1/nKey1) is a blob */
+  }else{
+    int nCmp;
+    int nStr;
+    int szHdr = aKey1[0];
+
+    nStr = (serial_type-12) / 2;
+    if( (szHdr + nStr) > nKey1 ){
+      pPKey2->errCode = (u8)SQLITE_CORRUPT_BKPT;
+      return 0;    /* Corruption */
+    }
+    nCmp = MIN( pPKey2->aMem[0].n, nStr );
+    res = memcmp(&aKey1[szHdr], pPKey2->aMem[0].z, nCmp);
+
+    if( res==0 ){
+      res = nStr - pPKey2->aMem[0].n;
+      if( res==0 ){
+        if( pPKey2->nField>1 ){
+          res = sqlite3VdbeRecordCompareWithSkip(nKey1, pKey1, pPKey2, 1);
+        }else{
+          res = pPKey2->default_rc;
+          pPKey2->eqSeen = 1;
+        }
+      }else if( res>0 ){
+        res = pPKey2->r2;
+      }else{
+        res = pPKey2->r1;
+      }
+    }else if( res>0 ){
+      res = pPKey2->r2;
+    }else{
+      res = pPKey2->r1;
+    }
+  }
+
+  assert( vdbeRecordCompareDebug(nKey1, pKey1, pPKey2, res)
+       || CORRUPT_DB
+       || pPKey2->pKeyInfo->db->mallocFailed
+  );
+  return res;
+}
+
+/*
+** Return a pointer to an sqlite3VdbeRecordCompare() compatible function
+** suitable for comparing serialized records to the unpacked record passed
+** as the only argument.
+*/
+SQLITE_PRIVATE RecordCompare sqlite3VdbeFindCompare(UnpackedRecord *p){
+  /* varintRecordCompareInt() and varintRecordCompareString() both assume
+  ** that the size-of-header varint that occurs at the start of each record
+  ** fits in a single byte (i.e. is 127 or less). varintRecordCompareInt()
+  ** also assumes that it is safe to overread a buffer by at least the 
+  ** maximum possible legal header size plus 8 bytes. Because there is
+  ** guaranteed to be at least 74 (but not 136) bytes of padding following each
+  ** buffer passed to varintRecordCompareInt() this makes it convenient to
+  ** limit the size of the header to 64 bytes in cases where the first field
+  ** is an integer.
+  **
+  ** The easiest way to enforce this limit is to consider only records with
+  ** 13 fields or less. If the first field is an integer, the maximum legal
+  ** header size is (12*5 + 1 + 1) bytes.  */
+  if( (p->pKeyInfo->nField + p->pKeyInfo->nXField)<=13 ){
+    int flags = p->aMem[0].flags;
+    if( p->pKeyInfo->aSortOrder[0] ){
+      p->r1 = 1;
+      p->r2 = -1;
+    }else{
+      p->r1 = -1;
+      p->r2 = 1;
+    }
+    if( (flags & MEM_Int) ){
+      return vdbeRecordCompareInt;
+    }
+    testcase( flags & MEM_Real );
+    testcase( flags & MEM_Null );
+    testcase( flags & MEM_Blob );
+    if( (flags & (MEM_Real|MEM_Null|MEM_Blob))==0 && p->pKeyInfo->aColl[0]==0 ){
+      assert( flags & MEM_Str );
+      return vdbeRecordCompareString;
+    }
+  }
+
+  return sqlite3VdbeRecordCompare;
+}
+
+/*
+** pCur points at an index entry created using the OP_MakeRecord opcode.
+** Read the rowid (the last field in the record) and store it in *rowid.
+** Return SQLITE_OK if everything works, or an error code otherwise.
+**
+** pCur might be pointing to text obtained from a corrupt database file.
+** So the content cannot be trusted.  Do appropriate checks on the content.
+*/
+SQLITE_PRIVATE int sqlite3VdbeIdxRowid(sqlite3 *db, BtCursor *pCur, i64 *rowid){
+  i64 nCellKey = 0;
+  int rc;
+  u32 szHdr;        /* Size of the header */
+  u32 typeRowid;    /* Serial type of the rowid */
+  u32 lenRowid;     /* Size of the rowid */
+  Mem m, v;
+
+  /* Get the size of the index entry.  Only indices entries of less
+  ** than 2GiB are support - anything large must be database corruption.
+  ** Any corruption is detected in sqlite3BtreeParseCellPtr(), though, so
+  ** this code can safely assume that nCellKey is 32-bits  
+  */
+  assert( sqlite3BtreeCursorIsValid(pCur) );
+  nCellKey = sqlite3BtreePayloadSize(pCur);
+  assert( (nCellKey & SQLITE_MAX_U32)==(u64)nCellKey );
+
+  /* Read in the complete content of the index entry */
+  sqlite3VdbeMemInit(&m, db, 0);
+  rc = sqlite3VdbeMemFromBtree(pCur, 0, (u32)nCellKey, 1, &m);
+  if( rc ){
+    return rc;
+  }
+
+  /* The index entry must begin with a header size */
+  (void)getVarint32((u8*)m.z, szHdr);
+  testcase( szHdr==3 );
+  testcase( szHdr==m.n );
+  if( unlikely(szHdr<3 || (int)szHdr>m.n) ){
+    goto idx_rowid_corruption;
+  }
+
+  /* The last field of the index should be an integer - the ROWID.
+  ** Verify that the last entry really is an integer. */
+  (void)getVarint32((u8*)&m.z[szHdr-1], typeRowid);
+  testcase( typeRowid==1 );
+  testcase( typeRowid==2 );
+  testcase( typeRowid==3 );
+  testcase( typeRowid==4 );
+  testcase( typeRowid==5 );
+  testcase( typeRowid==6 );
+  testcase( typeRowid==8 );
+  testcase( typeRowid==9 );
+  if( unlikely(typeRowid<1 || typeRowid>9 || typeRowid==7) ){
+    goto idx_rowid_corruption;
+  }
+  lenRowid = sqlite3SmallTypeSizes[typeRowid];
+  testcase( (u32)m.n==szHdr+lenRowid );
+  if( unlikely((u32)m.n<szHdr+lenRowid) ){
+    goto idx_rowid_corruption;
+  }
+
+  /* Fetch the integer off the end of the index record */
+  sqlite3VdbeSerialGet((u8*)&m.z[m.n-lenRowid], typeRowid, &v);
+  *rowid = v.u.i;
+  sqlite3VdbeMemRelease(&m);
+  return SQLITE_OK;
+
+  /* Jump here if database corruption is detected after m has been
+  ** allocated.  Free the m object and return SQLITE_CORRUPT. */
+idx_rowid_corruption:
+  testcase( m.szMalloc!=0 );
+  sqlite3VdbeMemRelease(&m);
+  return SQLITE_CORRUPT_BKPT;
+}
+
+/*
+** Compare the key of the index entry that cursor pC is pointing to against
+** the key string in pUnpacked.  Write into *pRes a number
+** that is negative, zero, or positive if pC is less than, equal to,
+** or greater than pUnpacked.  Return SQLITE_OK on success.
+**
+** pUnpacked is either created without a rowid or is truncated so that it
+** omits the rowid at the end.  The rowid at the end of the index entry
+** is ignored as well.  Hence, this routine only compares the prefixes 
+** of the keys prior to the final rowid, not the entire key.
+*/
+SQLITE_PRIVATE int sqlite3VdbeIdxKeyCompare(
+  sqlite3 *db,                     /* Database connection */
+  VdbeCursor *pC,                  /* The cursor to compare against */
+  UnpackedRecord *pUnpacked,       /* Unpacked version of key */
+  int *res                         /* Write the comparison result here */
+){
+  i64 nCellKey = 0;
+  int rc;
+  BtCursor *pCur;
+  Mem m;
+
+  assert( pC->eCurType==CURTYPE_BTREE );
+  pCur = pC->uc.pCursor;
+  assert( sqlite3BtreeCursorIsValid(pCur) );
+  nCellKey = sqlite3BtreePayloadSize(pCur);
+  /* nCellKey will always be between 0 and 0xffffffff because of the way
+  ** that btreeParseCellPtr() and sqlite3GetVarint32() are implemented */
+  if( nCellKey<=0 || nCellKey>0x7fffffff ){
+    *res = 0;
+    return SQLITE_CORRUPT_BKPT;
+  }
+  sqlite3VdbeMemInit(&m, db, 0);
+  rc = sqlite3VdbeMemFromBtree(pCur, 0, (u32)nCellKey, 1, &m);
+  if( rc ){
+    return rc;
+  }
+  *res = sqlite3VdbeRecordCompare(m.n, m.z, pUnpacked);
+  sqlite3VdbeMemRelease(&m);
+  return SQLITE_OK;
+}
+
+/*
+** This routine sets the value to be returned by subsequent calls to
+** sqlite3_changes() on the database handle 'db'. 
+*/
+SQLITE_PRIVATE void sqlite3VdbeSetChanges(sqlite3 *db, int nChange){
+  assert( sqlite3_mutex_held(db->mutex) );
+  db->nChange = nChange;
+  db->nTotalChange += nChange;
+}
+
+/*
+** Set a flag in the vdbe to update the change counter when it is finalised
+** or reset.
+*/
+SQLITE_PRIVATE void sqlite3VdbeCountChanges(Vdbe *v){
+  v->changeCntOn = 1;
+}
+
+/*
+** Mark every prepared statement associated with a database connection
+** as expired.
+**
+** An expired statement means that recompilation of the statement is
+** recommend.  Statements expire when things happen that make their
+** programs obsolete.  Removing user-defined functions or collating
+** sequences, or changing an authorization function are the types of
+** things that make prepared statements obsolete.
+*/
+SQLITE_PRIVATE void sqlite3ExpirePreparedStatements(sqlite3 *db){
+  Vdbe *p;
+  for(p = db->pVdbe; p; p=p->pNext){
+    p->expired = 1;
+  }
+}
+
+/*
+** Return the database associated with the Vdbe.
+*/
+SQLITE_PRIVATE sqlite3 *sqlite3VdbeDb(Vdbe *v){
+  return v->db;
+}
+
+/*
+** Return a pointer to an sqlite3_value structure containing the value bound
+** parameter iVar of VM v. Except, if the value is an SQL NULL, return 
+** 0 instead. Unless it is NULL, apply affinity aff (one of the SQLITE_AFF_*
+** constants) to the value before returning it.
+**
+** The returned value must be freed by the caller using sqlite3ValueFree().
+*/
+SQLITE_PRIVATE sqlite3_value *sqlite3VdbeGetBoundValue(Vdbe *v, int iVar, u8 aff){
+  assert( iVar>0 );
+  if( v ){
+    Mem *pMem = &v->aVar[iVar-1];
+    if( 0==(pMem->flags & MEM_Null) ){
+      sqlite3_value *pRet = sqlite3ValueNew(v->db);
+      if( pRet ){
+        sqlite3VdbeMemCopy((Mem *)pRet, pMem);
+        sqlite3ValueApplyAffinity(pRet, aff, SQLITE_UTF8);
+      }
+      return pRet;
+    }
+  }
+  return 0;
+}
+
+/*
+** Configure SQL variable iVar so that binding a new value to it signals
+** to sqlite3_reoptimize() that re-preparing the statement may result
+** in a better query plan.
+*/
+SQLITE_PRIVATE void sqlite3VdbeSetVarmask(Vdbe *v, int iVar){
+  assert( iVar>0 );
+  if( iVar>32 ){
+    v->expmask = 0xffffffff;
+  }else{
+    v->expmask |= ((u32)1 << (iVar-1));
+  }
+}
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/*
+** Transfer error message text from an sqlite3_vtab.zErrMsg (text stored
+** in memory obtained from sqlite3_malloc) into a Vdbe.zErrMsg (text stored
+** in memory obtained from sqlite3DbMalloc).
+*/
+SQLITE_PRIVATE void sqlite3VtabImportErrmsg(Vdbe *p, sqlite3_vtab *pVtab){
+  if( pVtab->zErrMsg ){
+    sqlite3 *db = p->db;
+    sqlite3DbFree(db, p->zErrMsg);
+    p->zErrMsg = sqlite3DbStrDup(db, pVtab->zErrMsg);
+    sqlite3_free(pVtab->zErrMsg);
+    pVtab->zErrMsg = 0;
+  }
+}
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+
+/*
+** If the second argument is not NULL, release any allocations associated 
+** with the memory cells in the p->aMem[] array. Also free the UnpackedRecord
+** structure itself, using sqlite3DbFree().
+**
+** This function is used to free UnpackedRecord structures allocated by
+** the vdbeUnpackRecord() function found in vdbeapi.c.
+*/
+static void vdbeFreeUnpacked(sqlite3 *db, UnpackedRecord *p){
+  if( p ){
+    int i;
+    for(i=0; i<p->nField; i++){
+      Mem *pMem = &p->aMem[i];
+      if( pMem->zMalloc ) sqlite3VdbeMemRelease(pMem);
+    }
+    sqlite3DbFree(db, p);
+  }
+}
+#endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
+
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+/*
+** Invoke the pre-update hook. If this is an UPDATE or DELETE pre-update call,
+** then cursor passed as the second argument should point to the row about
+** to be update or deleted. If the application calls sqlite3_preupdate_old(),
+** the required value will be read from the row the cursor points to.
+*/
+SQLITE_PRIVATE void sqlite3VdbePreUpdateHook(
+  Vdbe *v,                        /* Vdbe pre-update hook is invoked by */
+  VdbeCursor *pCsr,               /* Cursor to grab old.* values from */
+  int op,                         /* SQLITE_INSERT, UPDATE or DELETE */
+  const char *zDb,                /* Database name */
+  Table *pTab,                    /* Modified table */
+  i64 iKey1,                      /* Initial key value */
+  int iReg                        /* Register for new.* record */
+){
+  sqlite3 *db = v->db;
+  i64 iKey2;
+  PreUpdate preupdate;
+  const char *zTbl = pTab->zName;
+  static const u8 fakeSortOrder = 0;
+
+  assert( db->pPreUpdate==0 );
+  memset(&preupdate, 0, sizeof(PreUpdate));
+  if( op==SQLITE_UPDATE ){
+    iKey2 = v->aMem[iReg].u.i;
+  }else{
+    iKey2 = iKey1;
+  }
+
+  assert( pCsr->nField==pTab->nCol 
+       || (pCsr->nField==pTab->nCol+1 && op==SQLITE_DELETE && iReg==-1)
+  );
+
+  preupdate.v = v;
+  preupdate.pCsr = pCsr;
+  preupdate.op = op;
+  preupdate.iNewReg = iReg;
+  preupdate.keyinfo.db = db;
+  preupdate.keyinfo.enc = ENC(db);
+  preupdate.keyinfo.nField = pTab->nCol;
+  preupdate.keyinfo.aSortOrder = (u8*)&fakeSortOrder;
+  preupdate.iKey1 = iKey1;
+  preupdate.iKey2 = iKey2;
+  preupdate.pTab = pTab;
+
+  db->pPreUpdate = &preupdate;
+  db->xPreUpdateCallback(db->pPreUpdateArg, db, op, zDb, zTbl, iKey1, iKey2);
+  db->pPreUpdate = 0;
+  sqlite3DbFree(db, preupdate.aRecord);
+  vdbeFreeUnpacked(db, preupdate.pUnpacked);
+  vdbeFreeUnpacked(db, preupdate.pNewUnpacked);
+  if( preupdate.aNew ){
+    int i;
+    for(i=0; i<pCsr->nField; i++){
+      sqlite3VdbeMemRelease(&preupdate.aNew[i]);
+    }
+    sqlite3DbFree(db, preupdate.aNew);
+  }
+}
+#endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
+
+/************** End of vdbeaux.c *********************************************/
+/************** Begin file vdbeapi.c *****************************************/
+/*
+** 2004 May 26
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains code use to implement APIs that are part of the
+** VDBE.
+*/
+/* #include "sqliteInt.h" */
+/* #include "vdbeInt.h" */
+
+#ifndef SQLITE_OMIT_DEPRECATED
+/*
+** Return TRUE (non-zero) of the statement supplied as an argument needs
+** to be recompiled.  A statement needs to be recompiled whenever the
+** execution environment changes in a way that would alter the program
+** that sqlite3_prepare() generates.  For example, if new functions or
+** collating sequences are registered or if an authorizer function is
+** added or changed.
+*/
+SQLITE_API int sqlite3_expired(sqlite3_stmt *pStmt){
+  Vdbe *p = (Vdbe*)pStmt;
+  return p==0 || p->expired;
+}
+#endif
+
+/*
+** Check on a Vdbe to make sure it has not been finalized.  Log
+** an error and return true if it has been finalized (or is otherwise
+** invalid).  Return false if it is ok.
+*/
+static int vdbeSafety(Vdbe *p){
+  if( p->db==0 ){
+    sqlite3_log(SQLITE_MISUSE, "API called with finalized prepared statement");
+    return 1;
+  }else{
+    return 0;
+  }
+}
+static int vdbeSafetyNotNull(Vdbe *p){
+  if( p==0 ){
+    sqlite3_log(SQLITE_MISUSE, "API called with NULL prepared statement");
+    return 1;
+  }else{
+    return vdbeSafety(p);
+  }
+}
+
+#ifndef SQLITE_OMIT_TRACE
+/*
+** Invoke the profile callback.  This routine is only called if we already
+** know that the profile callback is defined and needs to be invoked.
+*/
+static SQLITE_NOINLINE void invokeProfileCallback(sqlite3 *db, Vdbe *p){
+  sqlite3_int64 iNow;
+  sqlite3_int64 iElapse;
+  assert( p->startTime>0 );
+  assert( db->xProfile!=0 || (db->mTrace & SQLITE_TRACE_PROFILE)!=0 );
+  assert( db->init.busy==0 );
+  assert( p->zSql!=0 );
+  sqlite3OsCurrentTimeInt64(db->pVfs, &iNow);
+  iElapse = (iNow - p->startTime)*1000000;
+  if( db->xProfile ){
+    db->xProfile(db->pProfileArg, p->zSql, iElapse);
+  }
+  if( db->mTrace & SQLITE_TRACE_PROFILE ){
+    db->xTrace(SQLITE_TRACE_PROFILE, db->pTraceArg, p, (void*)&iElapse);
+  }
+  p->startTime = 0;
+}
+/*
+** The checkProfileCallback(DB,P) macro checks to see if a profile callback
+** is needed, and it invokes the callback if it is needed.
+*/
+# define checkProfileCallback(DB,P) \
+   if( ((P)->startTime)>0 ){ invokeProfileCallback(DB,P); }
+#else
+# define checkProfileCallback(DB,P)  /*no-op*/
+#endif
+
+/*
+** The following routine destroys a virtual machine that is created by
+** the sqlite3_compile() routine. The integer returned is an SQLITE_
+** success/failure code that describes the result of executing the virtual
+** machine.
+**
+** This routine sets the error code and string returned by
+** sqlite3_errcode(), sqlite3_errmsg() and sqlite3_errmsg16().
+*/
+SQLITE_API int sqlite3_finalize(sqlite3_stmt *pStmt){
+  int rc;
+  if( pStmt==0 ){
+    /* IMPLEMENTATION-OF: R-57228-12904 Invoking sqlite3_finalize() on a NULL
+    ** pointer is a harmless no-op. */
+    rc = SQLITE_OK;
+  }else{
+    Vdbe *v = (Vdbe*)pStmt;
+    sqlite3 *db = v->db;
+    if( vdbeSafety(v) ) return SQLITE_MISUSE_BKPT;
+    sqlite3_mutex_enter(db->mutex);
+    checkProfileCallback(db, v);
+    rc = sqlite3VdbeFinalize(v);
+    rc = sqlite3ApiExit(db, rc);
+    sqlite3LeaveMutexAndCloseZombie(db);
+  }
+  return rc;
+}
+
+/*
+** Terminate the current execution of an SQL statement and reset it
+** back to its starting state so that it can be reused. A success code from
+** the prior execution is returned.
+**
+** This routine sets the error code and string returned by
+** sqlite3_errcode(), sqlite3_errmsg() and sqlite3_errmsg16().
+*/
+SQLITE_API int sqlite3_reset(sqlite3_stmt *pStmt){
+  int rc;
+  if( pStmt==0 ){
+    rc = SQLITE_OK;
+  }else{
+    Vdbe *v = (Vdbe*)pStmt;
+    sqlite3 *db = v->db;
+    sqlite3_mutex_enter(db->mutex);
+    checkProfileCallback(db, v);
+    rc = sqlite3VdbeReset(v);
+    sqlite3VdbeRewind(v);
+    assert( (rc & (db->errMask))==rc );
+    rc = sqlite3ApiExit(db, rc);
+    sqlite3_mutex_leave(db->mutex);
+  }
+  return rc;
+}
+
+/*
+** Set all the parameters in the compiled SQL statement to NULL.
+*/
+SQLITE_API int sqlite3_clear_bindings(sqlite3_stmt *pStmt){
+  int i;
+  int rc = SQLITE_OK;
+  Vdbe *p = (Vdbe*)pStmt;
+#if SQLITE_THREADSAFE
+  sqlite3_mutex *mutex = ((Vdbe*)pStmt)->db->mutex;
+#endif
+  sqlite3_mutex_enter(mutex);
+  for(i=0; i<p->nVar; i++){
+    sqlite3VdbeMemRelease(&p->aVar[i]);
+    p->aVar[i].flags = MEM_Null;
+  }
+  if( p->isPrepareV2 && p->expmask ){
+    p->expired = 1;
+  }
+  sqlite3_mutex_leave(mutex);
+  return rc;
+}
+
+
+/**************************** sqlite3_value_  *******************************
+** The following routines extract information from a Mem or sqlite3_value
+** structure.
+*/
+SQLITE_API const void *sqlite3_value_blob(sqlite3_value *pVal){
+  Mem *p = (Mem*)pVal;
+  if( p->flags & (MEM_Blob|MEM_Str) ){
+    if( ExpandBlob(p)!=SQLITE_OK ){
+      assert( p->flags==MEM_Null && p->z==0 );
+      return 0;
+    }
+    p->flags |= MEM_Blob;
+    return p->n ? p->z : 0;
+  }else{
+    return sqlite3_value_text(pVal);
+  }
+}
+SQLITE_API int sqlite3_value_bytes(sqlite3_value *pVal){
+  return sqlite3ValueBytes(pVal, SQLITE_UTF8);
+}
+SQLITE_API int sqlite3_value_bytes16(sqlite3_value *pVal){
+  return sqlite3ValueBytes(pVal, SQLITE_UTF16NATIVE);
+}
+SQLITE_API double sqlite3_value_double(sqlite3_value *pVal){
+  return sqlite3VdbeRealValue((Mem*)pVal);
+}
+SQLITE_API int sqlite3_value_int(sqlite3_value *pVal){
+  return (int)sqlite3VdbeIntValue((Mem*)pVal);
+}
+SQLITE_API sqlite_int64 sqlite3_value_int64(sqlite3_value *pVal){
+  return sqlite3VdbeIntValue((Mem*)pVal);
+}
+SQLITE_API unsigned int sqlite3_value_subtype(sqlite3_value *pVal){
+  Mem *pMem = (Mem*)pVal;
+  return ((pMem->flags & MEM_Subtype) ? pMem->eSubtype : 0);
+}
+SQLITE_API const unsigned char *sqlite3_value_text(sqlite3_value *pVal){
+  return (const unsigned char *)sqlite3ValueText(pVal, SQLITE_UTF8);
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API const void *sqlite3_value_text16(sqlite3_value* pVal){
+  return sqlite3ValueText(pVal, SQLITE_UTF16NATIVE);
+}
+SQLITE_API const void *sqlite3_value_text16be(sqlite3_value *pVal){
+  return sqlite3ValueText(pVal, SQLITE_UTF16BE);
+}
+SQLITE_API const void *sqlite3_value_text16le(sqlite3_value *pVal){
+  return sqlite3ValueText(pVal, SQLITE_UTF16LE);
+}
+#endif /* SQLITE_OMIT_UTF16 */
+/* EVIDENCE-OF: R-12793-43283 Every value in SQLite has one of five
+** fundamental datatypes: 64-bit signed integer 64-bit IEEE floating
+** point number string BLOB NULL
+*/
+SQLITE_API int sqlite3_value_type(sqlite3_value* pVal){
+  static const u8 aType[] = {
+     SQLITE_BLOB,     /* 0x00 */
+     SQLITE_NULL,     /* 0x01 */
+     SQLITE_TEXT,     /* 0x02 */
+     SQLITE_NULL,     /* 0x03 */
+     SQLITE_INTEGER,  /* 0x04 */
+     SQLITE_NULL,     /* 0x05 */
+     SQLITE_INTEGER,  /* 0x06 */
+     SQLITE_NULL,     /* 0x07 */
+     SQLITE_FLOAT,    /* 0x08 */
+     SQLITE_NULL,     /* 0x09 */
+     SQLITE_FLOAT,    /* 0x0a */
+     SQLITE_NULL,     /* 0x0b */
+     SQLITE_INTEGER,  /* 0x0c */
+     SQLITE_NULL,     /* 0x0d */
+     SQLITE_INTEGER,  /* 0x0e */
+     SQLITE_NULL,     /* 0x0f */
+     SQLITE_BLOB,     /* 0x10 */
+     SQLITE_NULL,     /* 0x11 */
+     SQLITE_TEXT,     /* 0x12 */
+     SQLITE_NULL,     /* 0x13 */
+     SQLITE_INTEGER,  /* 0x14 */
+     SQLITE_NULL,     /* 0x15 */
+     SQLITE_INTEGER,  /* 0x16 */
+     SQLITE_NULL,     /* 0x17 */
+     SQLITE_FLOAT,    /* 0x18 */
+     SQLITE_NULL,     /* 0x19 */
+     SQLITE_FLOAT,    /* 0x1a */
+     SQLITE_NULL,     /* 0x1b */
+     SQLITE_INTEGER,  /* 0x1c */
+     SQLITE_NULL,     /* 0x1d */
+     SQLITE_INTEGER,  /* 0x1e */
+     SQLITE_NULL,     /* 0x1f */
+  };
+  return aType[pVal->flags&MEM_AffMask];
+}
+
+/* Make a copy of an sqlite3_value object
+*/
+SQLITE_API sqlite3_value *sqlite3_value_dup(const sqlite3_value *pOrig){
+  sqlite3_value *pNew;
+  if( pOrig==0 ) return 0;
+  pNew = sqlite3_malloc( sizeof(*pNew) );
+  if( pNew==0 ) return 0;
+  memset(pNew, 0, sizeof(*pNew));
+  memcpy(pNew, pOrig, MEMCELLSIZE);
+  pNew->flags &= ~MEM_Dyn;
+  pNew->db = 0;
+  if( pNew->flags&(MEM_Str|MEM_Blob) ){
+    pNew->flags &= ~(MEM_Static|MEM_Dyn);
+    pNew->flags |= MEM_Ephem;
+    if( sqlite3VdbeMemMakeWriteable(pNew)!=SQLITE_OK ){
+      sqlite3ValueFree(pNew);
+      pNew = 0;
+    }
+  }
+  return pNew;
+}
+
+/* Destroy an sqlite3_value object previously obtained from
+** sqlite3_value_dup().
+*/
+SQLITE_API void sqlite3_value_free(sqlite3_value *pOld){
+  sqlite3ValueFree(pOld);
+}
+  
+
+/**************************** sqlite3_result_  *******************************
+** The following routines are used by user-defined functions to specify
+** the function result.
+**
+** The setStrOrError() function calls sqlite3VdbeMemSetStr() to store the
+** result as a string or blob but if the string or blob is too large, it
+** then sets the error code to SQLITE_TOOBIG
+**
+** The invokeValueDestructor(P,X) routine invokes destructor function X()
+** on value P is not going to be used and need to be destroyed.
+*/
+static void setResultStrOrError(
+  sqlite3_context *pCtx,  /* Function context */
+  const char *z,          /* String pointer */
+  int n,                  /* Bytes in string, or negative */
+  u8 enc,                 /* Encoding of z.  0 for BLOBs */
+  void (*xDel)(void*)     /* Destructor function */
+){
+  if( sqlite3VdbeMemSetStr(pCtx->pOut, z, n, enc, xDel)==SQLITE_TOOBIG ){
+    sqlite3_result_error_toobig(pCtx);
+  }
+}
+static int invokeValueDestructor(
+  const void *p,             /* Value to destroy */
+  void (*xDel)(void*),       /* The destructor */
+  sqlite3_context *pCtx      /* Set a SQLITE_TOOBIG error if no NULL */
+){
+  assert( xDel!=SQLITE_DYNAMIC );
+  if( xDel==0 ){
+    /* noop */
+  }else if( xDel==SQLITE_TRANSIENT ){
+    /* noop */
+  }else{
+    xDel((void*)p);
+  }
+  if( pCtx ) sqlite3_result_error_toobig(pCtx);
+  return SQLITE_TOOBIG;
+}
+SQLITE_API void sqlite3_result_blob(
+  sqlite3_context *pCtx, 
+  const void *z, 
+  int n, 
+  void (*xDel)(void *)
+){
+  assert( n>=0 );
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  setResultStrOrError(pCtx, z, n, 0, xDel);
+}
+SQLITE_API void sqlite3_result_blob64(
+  sqlite3_context *pCtx, 
+  const void *z, 
+  sqlite3_uint64 n,
+  void (*xDel)(void *)
+){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  assert( xDel!=SQLITE_DYNAMIC );
+  if( n>0x7fffffff ){
+    (void)invokeValueDestructor(z, xDel, pCtx);
+  }else{
+    setResultStrOrError(pCtx, z, (int)n, 0, xDel);
+  }
+}
+SQLITE_API void sqlite3_result_double(sqlite3_context *pCtx, double rVal){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  sqlite3VdbeMemSetDouble(pCtx->pOut, rVal);
+}
+SQLITE_API void sqlite3_result_error(sqlite3_context *pCtx, const char *z, int n){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  pCtx->isError = SQLITE_ERROR;
+  pCtx->fErrorOrAux = 1;
+  sqlite3VdbeMemSetStr(pCtx->pOut, z, n, SQLITE_UTF8, SQLITE_TRANSIENT);
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API void sqlite3_result_error16(sqlite3_context *pCtx, const void *z, int n){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  pCtx->isError = SQLITE_ERROR;
+  pCtx->fErrorOrAux = 1;
+  sqlite3VdbeMemSetStr(pCtx->pOut, z, n, SQLITE_UTF16NATIVE, SQLITE_TRANSIENT);
+}
+#endif
+SQLITE_API void sqlite3_result_int(sqlite3_context *pCtx, int iVal){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  sqlite3VdbeMemSetInt64(pCtx->pOut, (i64)iVal);
+}
+SQLITE_API void sqlite3_result_int64(sqlite3_context *pCtx, i64 iVal){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  sqlite3VdbeMemSetInt64(pCtx->pOut, iVal);
+}
+SQLITE_API void sqlite3_result_null(sqlite3_context *pCtx){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  sqlite3VdbeMemSetNull(pCtx->pOut);
+}
+SQLITE_API void sqlite3_result_subtype(sqlite3_context *pCtx, unsigned int eSubtype){
+  Mem *pOut = pCtx->pOut;
+  assert( sqlite3_mutex_held(pOut->db->mutex) );
+  pOut->eSubtype = eSubtype & 0xff;
+  pOut->flags |= MEM_Subtype;
+}
+SQLITE_API void sqlite3_result_text(
+  sqlite3_context *pCtx, 
+  const char *z, 
+  int n,
+  void (*xDel)(void *)
+){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  setResultStrOrError(pCtx, z, n, SQLITE_UTF8, xDel);
+}
+SQLITE_API void sqlite3_result_text64(
+  sqlite3_context *pCtx, 
+  const char *z, 
+  sqlite3_uint64 n,
+  void (*xDel)(void *),
+  unsigned char enc
+){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  assert( xDel!=SQLITE_DYNAMIC );
+  if( enc==SQLITE_UTF16 ) enc = SQLITE_UTF16NATIVE;
+  if( n>0x7fffffff ){
+    (void)invokeValueDestructor(z, xDel, pCtx);
+  }else{
+    setResultStrOrError(pCtx, z, (int)n, enc, xDel);
+  }
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API void sqlite3_result_text16(
+  sqlite3_context *pCtx, 
+  const void *z, 
+  int n, 
+  void (*xDel)(void *)
+){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  setResultStrOrError(pCtx, z, n, SQLITE_UTF16NATIVE, xDel);
+}
+SQLITE_API void sqlite3_result_text16be(
+  sqlite3_context *pCtx, 
+  const void *z, 
+  int n, 
+  void (*xDel)(void *)
+){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  setResultStrOrError(pCtx, z, n, SQLITE_UTF16BE, xDel);
+}
+SQLITE_API void sqlite3_result_text16le(
+  sqlite3_context *pCtx, 
+  const void *z, 
+  int n, 
+  void (*xDel)(void *)
+){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  setResultStrOrError(pCtx, z, n, SQLITE_UTF16LE, xDel);
+}
+#endif /* SQLITE_OMIT_UTF16 */
+SQLITE_API void sqlite3_result_value(sqlite3_context *pCtx, sqlite3_value *pValue){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  sqlite3VdbeMemCopy(pCtx->pOut, pValue);
+}
+SQLITE_API void sqlite3_result_zeroblob(sqlite3_context *pCtx, int n){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  sqlite3VdbeMemSetZeroBlob(pCtx->pOut, n);
+}
+SQLITE_API int sqlite3_result_zeroblob64(sqlite3_context *pCtx, u64 n){
+  Mem *pOut = pCtx->pOut;
+  assert( sqlite3_mutex_held(pOut->db->mutex) );
+  if( n>(u64)pOut->db->aLimit[SQLITE_LIMIT_LENGTH] ){
+    return SQLITE_TOOBIG;
+  }
+  sqlite3VdbeMemSetZeroBlob(pCtx->pOut, (int)n);
+  return SQLITE_OK;
+}
+SQLITE_API void sqlite3_result_error_code(sqlite3_context *pCtx, int errCode){
+  pCtx->isError = errCode;
+  pCtx->fErrorOrAux = 1;
+#ifdef SQLITE_DEBUG
+  if( pCtx->pVdbe ) pCtx->pVdbe->rcApp = errCode;
+#endif
+  if( pCtx->pOut->flags & MEM_Null ){
+    sqlite3VdbeMemSetStr(pCtx->pOut, sqlite3ErrStr(errCode), -1, 
+                         SQLITE_UTF8, SQLITE_STATIC);
+  }
+}
+
+/* Force an SQLITE_TOOBIG error. */
+SQLITE_API void sqlite3_result_error_toobig(sqlite3_context *pCtx){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  pCtx->isError = SQLITE_TOOBIG;
+  pCtx->fErrorOrAux = 1;
+  sqlite3VdbeMemSetStr(pCtx->pOut, "string or blob too big", -1, 
+                       SQLITE_UTF8, SQLITE_STATIC);
+}
+
+/* An SQLITE_NOMEM error. */
+SQLITE_API void sqlite3_result_error_nomem(sqlite3_context *pCtx){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  sqlite3VdbeMemSetNull(pCtx->pOut);
+  pCtx->isError = SQLITE_NOMEM_BKPT;
+  pCtx->fErrorOrAux = 1;
+  sqlite3OomFault(pCtx->pOut->db);
+}
+
+/*
+** This function is called after a transaction has been committed. It 
+** invokes callbacks registered with sqlite3_wal_hook() as required.
+*/
+static int doWalCallbacks(sqlite3 *db){
+  int rc = SQLITE_OK;
+#ifndef SQLITE_OMIT_WAL
+  int i;
+  for(i=0; i<db->nDb; i++){
+    Btree *pBt = db->aDb[i].pBt;
+    if( pBt ){
+      int nEntry;
+      sqlite3BtreeEnter(pBt);
+      nEntry = sqlite3PagerWalCallback(sqlite3BtreePager(pBt));
+      sqlite3BtreeLeave(pBt);
+      if( db->xWalCallback && nEntry>0 && rc==SQLITE_OK ){
+        rc = db->xWalCallback(db->pWalArg, db, db->aDb[i].zDbSName, nEntry);
+      }
+    }
+  }
+#endif
+  return rc;
+}
+
+
+/*
+** Execute the statement pStmt, either until a row of data is ready, the
+** statement is completely executed or an error occurs.
+**
+** This routine implements the bulk of the logic behind the sqlite_step()
+** API.  The only thing omitted is the automatic recompile if a 
+** schema change has occurred.  That detail is handled by the
+** outer sqlite3_step() wrapper procedure.
+*/
+static int sqlite3Step(Vdbe *p){
+  sqlite3 *db;
+  int rc;
+
+  assert(p);
+  if( p->magic!=VDBE_MAGIC_RUN ){
+    /* We used to require that sqlite3_reset() be called before retrying
+    ** sqlite3_step() after any error or after SQLITE_DONE.  But beginning
+    ** with version 3.7.0, we changed this so that sqlite3_reset() would
+    ** be called automatically instead of throwing the SQLITE_MISUSE error.
+    ** This "automatic-reset" change is not technically an incompatibility, 
+    ** since any application that receives an SQLITE_MISUSE is broken by
+    ** definition.
+    **
+    ** Nevertheless, some published applications that were originally written
+    ** for version 3.6.23 or earlier do in fact depend on SQLITE_MISUSE 
+    ** returns, and those were broken by the automatic-reset change.  As a
+    ** a work-around, the SQLITE_OMIT_AUTORESET compile-time restores the
+    ** legacy behavior of returning SQLITE_MISUSE for cases where the 
+    ** previous sqlite3_step() returned something other than a SQLITE_LOCKED
+    ** or SQLITE_BUSY error.
+    */
+#ifdef SQLITE_OMIT_AUTORESET
+    if( (rc = p->rc&0xff)==SQLITE_BUSY || rc==SQLITE_LOCKED ){
+      sqlite3_reset((sqlite3_stmt*)p);
+    }else{
+      return SQLITE_MISUSE_BKPT;
+    }
+#else
+    sqlite3_reset((sqlite3_stmt*)p);
+#endif
+  }
+
+  /* Check that malloc() has not failed. If it has, return early. */
+  db = p->db;
+  if( db->mallocFailed ){
+    p->rc = SQLITE_NOMEM;
+    return SQLITE_NOMEM_BKPT;
+  }
+
+  if( p->pc<=0 && p->expired ){
+    p->rc = SQLITE_SCHEMA;
+    rc = SQLITE_ERROR;
+    goto end_of_step;
+  }
+  if( p->pc<0 ){
+    /* If there are no other statements currently running, then
+    ** reset the interrupt flag.  This prevents a call to sqlite3_interrupt
+    ** from interrupting a statement that has not yet started.
+    */
+    if( db->nVdbeActive==0 ){
+      db->u1.isInterrupted = 0;
+    }
+
+    assert( db->nVdbeWrite>0 || db->autoCommit==0 
+        || (db->nDeferredCons==0 && db->nDeferredImmCons==0)
+    );
+
+#ifndef SQLITE_OMIT_TRACE
+    if( (db->xProfile || (db->mTrace & SQLITE_TRACE_PROFILE)!=0)
+        && !db->init.busy && p->zSql ){
+      sqlite3OsCurrentTimeInt64(db->pVfs, &p->startTime);
+    }else{
+      assert( p->startTime==0 );
+    }
+#endif
+
+    db->nVdbeActive++;
+    if( p->readOnly==0 ) db->nVdbeWrite++;
+    if( p->bIsReader ) db->nVdbeRead++;
+    p->pc = 0;
+  }
+#ifdef SQLITE_DEBUG
+  p->rcApp = SQLITE_OK;
+#endif
+#ifndef SQLITE_OMIT_EXPLAIN
+  if( p->explain ){
+    rc = sqlite3VdbeList(p);
+  }else
+#endif /* SQLITE_OMIT_EXPLAIN */
+  {
+    db->nVdbeExec++;
+    rc = sqlite3VdbeExec(p);
+    db->nVdbeExec--;
+  }
+
+#ifndef SQLITE_OMIT_TRACE
+  /* If the statement completed successfully, invoke the profile callback */
+  if( rc!=SQLITE_ROW ) checkProfileCallback(db, p);
+#endif
+
+  if( rc==SQLITE_DONE ){
+    assert( p->rc==SQLITE_OK );
+    p->rc = doWalCallbacks(db);
+    if( p->rc!=SQLITE_OK ){
+      rc = SQLITE_ERROR;
+    }
+  }
+
+  db->errCode = rc;
+  if( SQLITE_NOMEM==sqlite3ApiExit(p->db, p->rc) ){
+    p->rc = SQLITE_NOMEM_BKPT;
+  }
+end_of_step:
+  /* At this point local variable rc holds the value that should be 
+  ** returned if this statement was compiled using the legacy 
+  ** sqlite3_prepare() interface. According to the docs, this can only
+  ** be one of the values in the first assert() below. Variable p->rc 
+  ** contains the value that would be returned if sqlite3_finalize() 
+  ** were called on statement p.
+  */
+  assert( rc==SQLITE_ROW  || rc==SQLITE_DONE   || rc==SQLITE_ERROR 
+       || (rc&0xff)==SQLITE_BUSY || rc==SQLITE_MISUSE
+  );
+  assert( (p->rc!=SQLITE_ROW && p->rc!=SQLITE_DONE) || p->rc==p->rcApp );
+  if( p->isPrepareV2 && rc!=SQLITE_ROW && rc!=SQLITE_DONE ){
+    /* If this statement was prepared using sqlite3_prepare_v2(), and an
+    ** error has occurred, then return the error code in p->rc to the
+    ** caller. Set the error code in the database handle to the same value.
+    */ 
+    rc = sqlite3VdbeTransferError(p);
+  }
+  return (rc&db->errMask);
+}
+
+/*
+** This is the top-level implementation of sqlite3_step().  Call
+** sqlite3Step() to do most of the work.  If a schema error occurs,
+** call sqlite3Reprepare() and try again.
+*/
+SQLITE_API int sqlite3_step(sqlite3_stmt *pStmt){
+  int rc = SQLITE_OK;      /* Result from sqlite3Step() */
+  int rc2 = SQLITE_OK;     /* Result from sqlite3Reprepare() */
+  Vdbe *v = (Vdbe*)pStmt;  /* the prepared statement */
+  int cnt = 0;             /* Counter to prevent infinite loop of reprepares */
+  sqlite3 *db;             /* The database connection */
+
+  if( vdbeSafetyNotNull(v) ){
+    return SQLITE_MISUSE_BKPT;
+  }
+  db = v->db;
+  sqlite3_mutex_enter(db->mutex);
+  v->doingRerun = 0;
+  while( (rc = sqlite3Step(v))==SQLITE_SCHEMA
+         && cnt++ < SQLITE_MAX_SCHEMA_RETRY ){
+    int savedPc = v->pc;
+    rc2 = rc = sqlite3Reprepare(v);
+    if( rc!=SQLITE_OK) break;
+    sqlite3_reset(pStmt);
+    if( savedPc>=0 ) v->doingRerun = 1;
+    assert( v->expired==0 );
+  }
+  if( rc2!=SQLITE_OK ){
+    /* This case occurs after failing to recompile an sql statement. 
+    ** The error message from the SQL compiler has already been loaded 
+    ** into the database handle. This block copies the error message 
+    ** from the database handle into the statement and sets the statement
+    ** program counter to 0 to ensure that when the statement is 
+    ** finalized or reset the parser error message is available via
+    ** sqlite3_errmsg() and sqlite3_errcode().
+    */
+    const char *zErr = (const char *)sqlite3_value_text(db->pErr); 
+    sqlite3DbFree(db, v->zErrMsg);
+    if( !db->mallocFailed ){
+      v->zErrMsg = sqlite3DbStrDup(db, zErr);
+      v->rc = rc2;
+    } else {
+      v->zErrMsg = 0;
+      v->rc = rc = SQLITE_NOMEM_BKPT;
+    }
+  }
+  rc = sqlite3ApiExit(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+
+/*
+** Extract the user data from a sqlite3_context structure and return a
+** pointer to it.
+*/
+SQLITE_API void *sqlite3_user_data(sqlite3_context *p){
+  assert( p && p->pFunc );
+  return p->pFunc->pUserData;
+}
+
+/*
+** Extract the user data from a sqlite3_context structure and return a
+** pointer to it.
+**
+** IMPLEMENTATION-OF: R-46798-50301 The sqlite3_context_db_handle() interface
+** returns a copy of the pointer to the database connection (the 1st
+** parameter) of the sqlite3_create_function() and
+** sqlite3_create_function16() routines that originally registered the
+** application defined function.
+*/
+SQLITE_API sqlite3 *sqlite3_context_db_handle(sqlite3_context *p){
+  assert( p && p->pOut );
+  return p->pOut->db;
+}
+
+/*
+** Return the current time for a statement.  If the current time
+** is requested more than once within the same run of a single prepared
+** statement, the exact same time is returned for each invocation regardless
+** of the amount of time that elapses between invocations.  In other words,
+** the time returned is always the time of the first call.
+*/
+SQLITE_PRIVATE sqlite3_int64 sqlite3StmtCurrentTime(sqlite3_context *p){
+  int rc;
+#ifndef SQLITE_ENABLE_STAT3_OR_STAT4
+  sqlite3_int64 *piTime = &p->pVdbe->iCurrentTime;
+  assert( p->pVdbe!=0 );
+#else
+  sqlite3_int64 iTime = 0;
+  sqlite3_int64 *piTime = p->pVdbe!=0 ? &p->pVdbe->iCurrentTime : &iTime;
+#endif
+  if( *piTime==0 ){
+    rc = sqlite3OsCurrentTimeInt64(p->pOut->db->pVfs, piTime);
+    if( rc ) *piTime = 0;
+  }
+  return *piTime;
+}
+
+/*
+** The following is the implementation of an SQL function that always
+** fails with an error message stating that the function is used in the
+** wrong context.  The sqlite3_overload_function() API might construct
+** SQL function that use this routine so that the functions will exist
+** for name resolution but are actually overloaded by the xFindFunction
+** method of virtual tables.
+*/
+SQLITE_PRIVATE void sqlite3InvalidFunction(
+  sqlite3_context *context,  /* The function calling context */
+  int NotUsed,               /* Number of arguments to the function */
+  sqlite3_value **NotUsed2   /* Value of each argument */
+){
+  const char *zName = context->pFunc->zName;
+  char *zErr;
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  zErr = sqlite3_mprintf(
+      "unable to use function %s in the requested context", zName);
+  sqlite3_result_error(context, zErr, -1);
+  sqlite3_free(zErr);
+}
+
+/*
+** Create a new aggregate context for p and return a pointer to
+** its pMem->z element.
+*/
+static SQLITE_NOINLINE void *createAggContext(sqlite3_context *p, int nByte){
+  Mem *pMem = p->pMem;
+  assert( (pMem->flags & MEM_Agg)==0 );
+  if( nByte<=0 ){
+    sqlite3VdbeMemSetNull(pMem);
+    pMem->z = 0;
+  }else{
+    sqlite3VdbeMemClearAndResize(pMem, nByte);
+    pMem->flags = MEM_Agg;
+    pMem->u.pDef = p->pFunc;
+    if( pMem->z ){
+      memset(pMem->z, 0, nByte);
+    }
+  }
+  return (void*)pMem->z;
+}
+
+/*
+** Allocate or return the aggregate context for a user function.  A new
+** context is allocated on the first call.  Subsequent calls return the
+** same context that was returned on prior calls.
+*/
+SQLITE_API void *sqlite3_aggregate_context(sqlite3_context *p, int nByte){
+  assert( p && p->pFunc && p->pFunc->xFinalize );
+  assert( sqlite3_mutex_held(p->pOut->db->mutex) );
+  testcase( nByte<0 );
+  if( (p->pMem->flags & MEM_Agg)==0 ){
+    return createAggContext(p, nByte);
+  }else{
+    return (void*)p->pMem->z;
+  }
+}
+
+/*
+** Return the auxiliary data pointer, if any, for the iArg'th argument to
+** the user-function defined by pCtx.
+*/
+SQLITE_API void *sqlite3_get_auxdata(sqlite3_context *pCtx, int iArg){
+  AuxData *pAuxData;
+
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+#if SQLITE_ENABLE_STAT3_OR_STAT4
+  if( pCtx->pVdbe==0 ) return 0;
+#else
+  assert( pCtx->pVdbe!=0 );
+#endif
+  for(pAuxData=pCtx->pVdbe->pAuxData; pAuxData; pAuxData=pAuxData->pNext){
+    if( pAuxData->iOp==pCtx->iOp && pAuxData->iArg==iArg ) break;
+  }
+
+  return (pAuxData ? pAuxData->pAux : 0);
+}
+
+/*
+** Set the auxiliary data pointer and delete function, for the iArg'th
+** argument to the user-function defined by pCtx. Any previous value is
+** deleted by calling the delete function specified when it was set.
+*/
+SQLITE_API void sqlite3_set_auxdata(
+  sqlite3_context *pCtx, 
+  int iArg, 
+  void *pAux, 
+  void (*xDelete)(void*)
+){
+  AuxData *pAuxData;
+  Vdbe *pVdbe = pCtx->pVdbe;
+
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  if( iArg<0 ) goto failed;
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  if( pVdbe==0 ) goto failed;
+#else
+  assert( pVdbe!=0 );
+#endif
+
+  for(pAuxData=pVdbe->pAuxData; pAuxData; pAuxData=pAuxData->pNext){
+    if( pAuxData->iOp==pCtx->iOp && pAuxData->iArg==iArg ) break;
+  }
+  if( pAuxData==0 ){
+    pAuxData = sqlite3DbMallocZero(pVdbe->db, sizeof(AuxData));
+    if( !pAuxData ) goto failed;
+    pAuxData->iOp = pCtx->iOp;
+    pAuxData->iArg = iArg;
+    pAuxData->pNext = pVdbe->pAuxData;
+    pVdbe->pAuxData = pAuxData;
+    if( pCtx->fErrorOrAux==0 ){
+      pCtx->isError = 0;
+      pCtx->fErrorOrAux = 1;
+    }
+  }else if( pAuxData->xDelete ){
+    pAuxData->xDelete(pAuxData->pAux);
+  }
+
+  pAuxData->pAux = pAux;
+  pAuxData->xDelete = xDelete;
+  return;
+
+failed:
+  if( xDelete ){
+    xDelete(pAux);
+  }
+}
+
+#ifndef SQLITE_OMIT_DEPRECATED
+/*
+** Return the number of times the Step function of an aggregate has been 
+** called.
+**
+** This function is deprecated.  Do not use it for new code.  It is
+** provide only to avoid breaking legacy code.  New aggregate function
+** implementations should keep their own counts within their aggregate
+** context.
+*/
+SQLITE_API int sqlite3_aggregate_count(sqlite3_context *p){
+  assert( p && p->pMem && p->pFunc && p->pFunc->xFinalize );
+  return p->pMem->n;
+}
+#endif
+
+/*
+** Return the number of columns in the result set for the statement pStmt.
+*/
+SQLITE_API int sqlite3_column_count(sqlite3_stmt *pStmt){
+  Vdbe *pVm = (Vdbe *)pStmt;
+  return pVm ? pVm->nResColumn : 0;
+}
+
+/*
+** Return the number of values available from the current row of the
+** currently executing statement pStmt.
+*/
+SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt){
+  Vdbe *pVm = (Vdbe *)pStmt;
+  if( pVm==0 || pVm->pResultSet==0 ) return 0;
+  return pVm->nResColumn;
+}
+
+/*
+** Return a pointer to static memory containing an SQL NULL value.
+*/
+static const Mem *columnNullValue(void){
+  /* Even though the Mem structure contains an element
+  ** of type i64, on certain architectures (x86) with certain compiler
+  ** switches (-Os), gcc may align this Mem object on a 4-byte boundary
+  ** instead of an 8-byte one. This all works fine, except that when
+  ** running with SQLITE_DEBUG defined the SQLite code sometimes assert()s
+  ** that a Mem structure is located on an 8-byte boundary. To prevent
+  ** these assert()s from failing, when building with SQLITE_DEBUG defined
+  ** using gcc, we force nullMem to be 8-byte aligned using the magical
+  ** __attribute__((aligned(8))) macro.  */
+  static const Mem nullMem 
+#if defined(SQLITE_DEBUG) && defined(__GNUC__)
+    __attribute__((aligned(8))) 
+#endif
+    = {
+        /* .u          = */ {0},
+        /* .flags      = */ (u16)MEM_Null,
+        /* .enc        = */ (u8)0,
+        /* .eSubtype   = */ (u8)0,
+        /* .n          = */ (int)0,
+        /* .z          = */ (char*)0,
+        /* .zMalloc    = */ (char*)0,
+        /* .szMalloc   = */ (int)0,
+        /* .uTemp      = */ (u32)0,
+        /* .db         = */ (sqlite3*)0,
+        /* .xDel       = */ (void(*)(void*))0,
+#ifdef SQLITE_DEBUG
+        /* .pScopyFrom = */ (Mem*)0,
+        /* .pFiller    = */ (void*)0,
+#endif
+      };
+  return &nullMem;
+}
+
+/*
+** Check to see if column iCol of the given statement is valid.  If
+** it is, return a pointer to the Mem for the value of that column.
+** If iCol is not valid, return a pointer to a Mem which has a value
+** of NULL.
+*/
+static Mem *columnMem(sqlite3_stmt *pStmt, int i){
+  Vdbe *pVm;
+  Mem *pOut;
+
+  pVm = (Vdbe *)pStmt;
+  if( pVm==0 ) return (Mem*)columnNullValue();
+  assert( pVm->db );
+  sqlite3_mutex_enter(pVm->db->mutex);
+  if( pVm->pResultSet!=0 && i<pVm->nResColumn && i>=0 ){
+    pOut = &pVm->pResultSet[i];
+  }else{
+    sqlite3Error(pVm->db, SQLITE_RANGE);
+    pOut = (Mem*)columnNullValue();
+  }
+  return pOut;
+}
+
+/*
+** This function is called after invoking an sqlite3_value_XXX function on a 
+** column value (i.e. a value returned by evaluating an SQL expression in the
+** select list of a SELECT statement) that may cause a malloc() failure. If 
+** malloc() has failed, the threads mallocFailed flag is cleared and the result
+** code of statement pStmt set to SQLITE_NOMEM.
+**
+** Specifically, this is called from within:
+**
+**     sqlite3_column_int()
+**     sqlite3_column_int64()
+**     sqlite3_column_text()
+**     sqlite3_column_text16()
+**     sqlite3_column_real()
+**     sqlite3_column_bytes()
+**     sqlite3_column_bytes16()
+**     sqiite3_column_blob()
+*/
+static void columnMallocFailure(sqlite3_stmt *pStmt)
+{
+  /* If malloc() failed during an encoding conversion within an
+  ** sqlite3_column_XXX API, then set the return code of the statement to
+  ** SQLITE_NOMEM. The next call to _step() (if any) will return SQLITE_ERROR
+  ** and _finalize() will return NOMEM.
+  */
+  Vdbe *p = (Vdbe *)pStmt;
+  if( p ){
+    assert( p->db!=0 );
+    assert( sqlite3_mutex_held(p->db->mutex) );
+    p->rc = sqlite3ApiExit(p->db, p->rc);
+    sqlite3_mutex_leave(p->db->mutex);
+  }
+}
+
+/**************************** sqlite3_column_  *******************************
+** The following routines are used to access elements of the current row
+** in the result set.
+*/
+SQLITE_API const void *sqlite3_column_blob(sqlite3_stmt *pStmt, int i){
+  const void *val;
+  val = sqlite3_value_blob( columnMem(pStmt,i) );
+  /* Even though there is no encoding conversion, value_blob() might
+  ** need to call malloc() to expand the result of a zeroblob() 
+  ** expression. 
+  */
+  columnMallocFailure(pStmt);
+  return val;
+}
+SQLITE_API int sqlite3_column_bytes(sqlite3_stmt *pStmt, int i){
+  int val = sqlite3_value_bytes( columnMem(pStmt,i) );
+  columnMallocFailure(pStmt);
+  return val;
+}
+SQLITE_API int sqlite3_column_bytes16(sqlite3_stmt *pStmt, int i){
+  int val = sqlite3_value_bytes16( columnMem(pStmt,i) );
+  columnMallocFailure(pStmt);
+  return val;
+}
+SQLITE_API double sqlite3_column_double(sqlite3_stmt *pStmt, int i){
+  double val = sqlite3_value_double( columnMem(pStmt,i) );
+  columnMallocFailure(pStmt);
+  return val;
+}
+SQLITE_API int sqlite3_column_int(sqlite3_stmt *pStmt, int i){
+  int val = sqlite3_value_int( columnMem(pStmt,i) );
+  columnMallocFailure(pStmt);
+  return val;
+}
+SQLITE_API sqlite_int64 sqlite3_column_int64(sqlite3_stmt *pStmt, int i){
+  sqlite_int64 val = sqlite3_value_int64( columnMem(pStmt,i) );
+  columnMallocFailure(pStmt);
+  return val;
+}
+SQLITE_API const unsigned char *sqlite3_column_text(sqlite3_stmt *pStmt, int i){
+  const unsigned char *val = sqlite3_value_text( columnMem(pStmt,i) );
+  columnMallocFailure(pStmt);
+  return val;
+}
+SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt *pStmt, int i){
+  Mem *pOut = columnMem(pStmt, i);
+  if( pOut->flags&MEM_Static ){
+    pOut->flags &= ~MEM_Static;
+    pOut->flags |= MEM_Ephem;
+  }
+  columnMallocFailure(pStmt);
+  return (sqlite3_value *)pOut;
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API const void *sqlite3_column_text16(sqlite3_stmt *pStmt, int i){
+  const void *val = sqlite3_value_text16( columnMem(pStmt,i) );
+  columnMallocFailure(pStmt);
+  return val;
+}
+#endif /* SQLITE_OMIT_UTF16 */
+SQLITE_API int sqlite3_column_type(sqlite3_stmt *pStmt, int i){
+  int iType = sqlite3_value_type( columnMem(pStmt,i) );
+  columnMallocFailure(pStmt);
+  return iType;
+}
+
+/*
+** Convert the N-th element of pStmt->pColName[] into a string using
+** xFunc() then return that string.  If N is out of range, return 0.
+**
+** There are up to 5 names for each column.  useType determines which
+** name is returned.  Here are the names:
+**
+**    0      The column name as it should be displayed for output
+**    1      The datatype name for the column
+**    2      The name of the database that the column derives from
+**    3      The name of the table that the column derives from
+**    4      The name of the table column that the result column derives from
+**
+** If the result is not a simple column reference (if it is an expression
+** or a constant) then useTypes 2, 3, and 4 return NULL.
+*/
+static const void *columnName(
+  sqlite3_stmt *pStmt,
+  int N,
+  const void *(*xFunc)(Mem*),
+  int useType
+){
+  const void *ret;
+  Vdbe *p;
+  int n;
+  sqlite3 *db;
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( pStmt==0 ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  ret = 0;
+  p = (Vdbe *)pStmt;
+  db = p->db;
+  assert( db!=0 );
+  n = sqlite3_column_count(pStmt);
+  if( N<n && N>=0 ){
+    N += useType*n;
+    sqlite3_mutex_enter(db->mutex);
+    assert( db->mallocFailed==0 );
+    ret = xFunc(&p->aColName[N]);
+     /* A malloc may have failed inside of the xFunc() call. If this
+    ** is the case, clear the mallocFailed flag and return NULL.
+    */
+    if( db->mallocFailed ){
+      sqlite3OomClear(db);
+      ret = 0;
+    }
+    sqlite3_mutex_leave(db->mutex);
+  }
+  return ret;
+}
+
+/*
+** Return the name of the Nth column of the result set returned by SQL
+** statement pStmt.
+*/
+SQLITE_API const char *sqlite3_column_name(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_NAME);
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API const void *sqlite3_column_name16(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_NAME);
+}
+#endif
+
+/*
+** Constraint:  If you have ENABLE_COLUMN_METADATA then you must
+** not define OMIT_DECLTYPE.
+*/
+#if defined(SQLITE_OMIT_DECLTYPE) && defined(SQLITE_ENABLE_COLUMN_METADATA)
+# error "Must not define both SQLITE_OMIT_DECLTYPE \
+         and SQLITE_ENABLE_COLUMN_METADATA"
+#endif
+
+#ifndef SQLITE_OMIT_DECLTYPE
+/*
+** Return the column declaration type (if applicable) of the 'i'th column
+** of the result set of SQL statement pStmt.
+*/
+SQLITE_API const char *sqlite3_column_decltype(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_DECLTYPE);
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API const void *sqlite3_column_decltype16(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_DECLTYPE);
+}
+#endif /* SQLITE_OMIT_UTF16 */
+#endif /* SQLITE_OMIT_DECLTYPE */
+
+#ifdef SQLITE_ENABLE_COLUMN_METADATA
+/*
+** Return the name of the database from which a result column derives.
+** NULL is returned if the result column is an expression or constant or
+** anything else which is not an unambiguous reference to a database column.
+*/
+SQLITE_API const char *sqlite3_column_database_name(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_DATABASE);
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API const void *sqlite3_column_database_name16(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_DATABASE);
+}
+#endif /* SQLITE_OMIT_UTF16 */
+
+/*
+** Return the name of the table from which a result column derives.
+** NULL is returned if the result column is an expression or constant or
+** anything else which is not an unambiguous reference to a database column.
+*/
+SQLITE_API const char *sqlite3_column_table_name(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_TABLE);
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API const void *sqlite3_column_table_name16(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_TABLE);
+}
+#endif /* SQLITE_OMIT_UTF16 */
+
+/*
+** Return the name of the table column from which a result column derives.
+** NULL is returned if the result column is an expression or constant or
+** anything else which is not an unambiguous reference to a database column.
+*/
+SQLITE_API const char *sqlite3_column_origin_name(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_COLUMN);
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API const void *sqlite3_column_origin_name16(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_COLUMN);
+}
+#endif /* SQLITE_OMIT_UTF16 */
+#endif /* SQLITE_ENABLE_COLUMN_METADATA */
+
+
+/******************************* sqlite3_bind_  ***************************
+** 
+** Routines used to attach values to wildcards in a compiled SQL statement.
+*/
+/*
+** Unbind the value bound to variable i in virtual machine p. This is the 
+** the same as binding a NULL value to the column. If the "i" parameter is
+** out of range, then SQLITE_RANGE is returned. Othewise SQLITE_OK.
+**
+** A successful evaluation of this routine acquires the mutex on p.
+** the mutex is released if any kind of error occurs.
+**
+** The error code stored in database p->db is overwritten with the return
+** value in any case.
+*/
+static int vdbeUnbind(Vdbe *p, int i){
+  Mem *pVar;
+  if( vdbeSafetyNotNull(p) ){
+    return SQLITE_MISUSE_BKPT;
+  }
+  sqlite3_mutex_enter(p->db->mutex);
+  if( p->magic!=VDBE_MAGIC_RUN || p->pc>=0 ){
+    sqlite3Error(p->db, SQLITE_MISUSE);
+    sqlite3_mutex_leave(p->db->mutex);
+    sqlite3_log(SQLITE_MISUSE, 
+        "bind on a busy prepared statement: [%s]", p->zSql);
+    return SQLITE_MISUSE_BKPT;
+  }
+  if( i<1 || i>p->nVar ){
+    sqlite3Error(p->db, SQLITE_RANGE);
+    sqlite3_mutex_leave(p->db->mutex);
+    return SQLITE_RANGE;
+  }
+  i--;
+  pVar = &p->aVar[i];
+  sqlite3VdbeMemRelease(pVar);
+  pVar->flags = MEM_Null;
+  sqlite3Error(p->db, SQLITE_OK);
+
+  /* If the bit corresponding to this variable in Vdbe.expmask is set, then 
+  ** binding a new value to this variable invalidates the current query plan.
+  **
+  ** IMPLEMENTATION-OF: R-48440-37595 If the specific value bound to host
+  ** parameter in the WHERE clause might influence the choice of query plan
+  ** for a statement, then the statement will be automatically recompiled,
+  ** as if there had been a schema change, on the first sqlite3_step() call
+  ** following any change to the bindings of that parameter.
+  */
+  if( p->isPrepareV2 &&
+     ((i<32 && p->expmask & ((u32)1 << i)) || p->expmask==0xffffffff)
+  ){
+    p->expired = 1;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Bind a text or BLOB value.
+*/
+static int bindText(
+  sqlite3_stmt *pStmt,   /* The statement to bind against */
+  int i,                 /* Index of the parameter to bind */
+  const void *zData,     /* Pointer to the data to be bound */
+  int nData,             /* Number of bytes of data to be bound */
+  void (*xDel)(void*),   /* Destructor for the data */
+  u8 encoding            /* Encoding for the data */
+){
+  Vdbe *p = (Vdbe *)pStmt;
+  Mem *pVar;
+  int rc;
+
+  rc = vdbeUnbind(p, i);
+  if( rc==SQLITE_OK ){
+    if( zData!=0 ){
+      pVar = &p->aVar[i-1];
+      rc = sqlite3VdbeMemSetStr(pVar, zData, nData, encoding, xDel);
+      if( rc==SQLITE_OK && encoding!=0 ){
+        rc = sqlite3VdbeChangeEncoding(pVar, ENC(p->db));
+      }
+      sqlite3Error(p->db, rc);
+      rc = sqlite3ApiExit(p->db, rc);
+    }
+    sqlite3_mutex_leave(p->db->mutex);
+  }else if( xDel!=SQLITE_STATIC && xDel!=SQLITE_TRANSIENT ){
+    xDel((void*)zData);
+  }
+  return rc;
+}
+
+
+/*
+** Bind a blob value to an SQL statement variable.
+*/
+SQLITE_API int sqlite3_bind_blob(
+  sqlite3_stmt *pStmt, 
+  int i, 
+  const void *zData, 
+  int nData, 
+  void (*xDel)(void*)
+){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( nData<0 ) return SQLITE_MISUSE_BKPT;
+#endif
+  return bindText(pStmt, i, zData, nData, xDel, 0);
+}
+SQLITE_API int sqlite3_bind_blob64(
+  sqlite3_stmt *pStmt, 
+  int i, 
+  const void *zData, 
+  sqlite3_uint64 nData, 
+  void (*xDel)(void*)
+){
+  assert( xDel!=SQLITE_DYNAMIC );
+  if( nData>0x7fffffff ){
+    return invokeValueDestructor(zData, xDel, 0);
+  }else{
+    return bindText(pStmt, i, zData, (int)nData, xDel, 0);
+  }
+}
+SQLITE_API int sqlite3_bind_double(sqlite3_stmt *pStmt, int i, double rValue){
+  int rc;
+  Vdbe *p = (Vdbe *)pStmt;
+  rc = vdbeUnbind(p, i);
+  if( rc==SQLITE_OK ){
+    sqlite3VdbeMemSetDouble(&p->aVar[i-1], rValue);
+    sqlite3_mutex_leave(p->db->mutex);
+  }
+  return rc;
+}
+SQLITE_API int sqlite3_bind_int(sqlite3_stmt *p, int i, int iValue){
+  return sqlite3_bind_int64(p, i, (i64)iValue);
+}
+SQLITE_API int sqlite3_bind_int64(sqlite3_stmt *pStmt, int i, sqlite_int64 iValue){
+  int rc;
+  Vdbe *p = (Vdbe *)pStmt;
+  rc = vdbeUnbind(p, i);
+  if( rc==SQLITE_OK ){
+    sqlite3VdbeMemSetInt64(&p->aVar[i-1], iValue);
+    sqlite3_mutex_leave(p->db->mutex);
+  }
+  return rc;
+}
+SQLITE_API int sqlite3_bind_null(sqlite3_stmt *pStmt, int i){
+  int rc;
+  Vdbe *p = (Vdbe*)pStmt;
+  rc = vdbeUnbind(p, i);
+  if( rc==SQLITE_OK ){
+    sqlite3_mutex_leave(p->db->mutex);
+  }
+  return rc;
+}
+SQLITE_API int sqlite3_bind_text( 
+  sqlite3_stmt *pStmt, 
+  int i, 
+  const char *zData, 
+  int nData, 
+  void (*xDel)(void*)
+){
+  return bindText(pStmt, i, zData, nData, xDel, SQLITE_UTF8);
+}
+SQLITE_API int sqlite3_bind_text64( 
+  sqlite3_stmt *pStmt, 
+  int i, 
+  const char *zData, 
+  sqlite3_uint64 nData, 
+  void (*xDel)(void*),
+  unsigned char enc
+){
+  assert( xDel!=SQLITE_DYNAMIC );
+  if( nData>0x7fffffff ){
+    return invokeValueDestructor(zData, xDel, 0);
+  }else{
+    if( enc==SQLITE_UTF16 ) enc = SQLITE_UTF16NATIVE;
+    return bindText(pStmt, i, zData, (int)nData, xDel, enc);
+  }
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API int sqlite3_bind_text16(
+  sqlite3_stmt *pStmt, 
+  int i, 
+  const void *zData, 
+  int nData, 
+  void (*xDel)(void*)
+){
+  return bindText(pStmt, i, zData, nData, xDel, SQLITE_UTF16NATIVE);
+}
+#endif /* SQLITE_OMIT_UTF16 */
+SQLITE_API int sqlite3_bind_value(sqlite3_stmt *pStmt, int i, const sqlite3_value *pValue){
+  int rc;
+  switch( sqlite3_value_type((sqlite3_value*)pValue) ){
+    case SQLITE_INTEGER: {
+      rc = sqlite3_bind_int64(pStmt, i, pValue->u.i);
+      break;
+    }
+    case SQLITE_FLOAT: {
+      rc = sqlite3_bind_double(pStmt, i, pValue->u.r);
+      break;
+    }
+    case SQLITE_BLOB: {
+      if( pValue->flags & MEM_Zero ){
+        rc = sqlite3_bind_zeroblob(pStmt, i, pValue->u.nZero);
+      }else{
+        rc = sqlite3_bind_blob(pStmt, i, pValue->z, pValue->n,SQLITE_TRANSIENT);
+      }
+      break;
+    }
+    case SQLITE_TEXT: {
+      rc = bindText(pStmt,i,  pValue->z, pValue->n, SQLITE_TRANSIENT,
+                              pValue->enc);
+      break;
+    }
+    default: {
+      rc = sqlite3_bind_null(pStmt, i);
+      break;
+    }
+  }
+  return rc;
+}
+SQLITE_API int sqlite3_bind_zeroblob(sqlite3_stmt *pStmt, int i, int n){
+  int rc;
+  Vdbe *p = (Vdbe *)pStmt;
+  rc = vdbeUnbind(p, i);
+  if( rc==SQLITE_OK ){
+    sqlite3VdbeMemSetZeroBlob(&p->aVar[i-1], n);
+    sqlite3_mutex_leave(p->db->mutex);
+  }
+  return rc;
+}
+SQLITE_API int sqlite3_bind_zeroblob64(sqlite3_stmt *pStmt, int i, sqlite3_uint64 n){
+  int rc;
+  Vdbe *p = (Vdbe *)pStmt;
+  sqlite3_mutex_enter(p->db->mutex);
+  if( n>(u64)p->db->aLimit[SQLITE_LIMIT_LENGTH] ){
+    rc = SQLITE_TOOBIG;
+  }else{
+    assert( (n & 0x7FFFFFFF)==n );
+    rc = sqlite3_bind_zeroblob(pStmt, i, n);
+  }
+  rc = sqlite3ApiExit(p->db, rc);
+  sqlite3_mutex_leave(p->db->mutex);
+  return rc;
+}
+
+/*
+** Return the number of wildcards that can be potentially bound to.
+** This routine is added to support DBD::SQLite.  
+*/
+SQLITE_API int sqlite3_bind_parameter_count(sqlite3_stmt *pStmt){
+  Vdbe *p = (Vdbe*)pStmt;
+  return p ? p->nVar : 0;
+}
+
+/*
+** Return the name of a wildcard parameter.  Return NULL if the index
+** is out of range or if the wildcard is unnamed.
+**
+** The result is always UTF-8.
+*/
+SQLITE_API const char *sqlite3_bind_parameter_name(sqlite3_stmt *pStmt, int i){
+  Vdbe *p = (Vdbe*)pStmt;
+  if( p==0 || i<1 || i>p->nzVar ){
+    return 0;
+  }
+  return p->azVar[i-1];
+}
+
+/*
+** Given a wildcard parameter name, return the index of the variable
+** with that name.  If there is no variable with the given name,
+** return 0.
+*/
+SQLITE_PRIVATE int sqlite3VdbeParameterIndex(Vdbe *p, const char *zName, int nName){
+  int i;
+  if( p==0 ){
+    return 0;
+  }
+  if( zName ){
+    for(i=0; i<p->nzVar; i++){
+      const char *z = p->azVar[i];
+      if( z && strncmp(z,zName,nName)==0 && z[nName]==0 ){
+        return i+1;
+      }
+    }
+  }
+  return 0;
+}
+SQLITE_API int sqlite3_bind_parameter_index(sqlite3_stmt *pStmt, const char *zName){
+  return sqlite3VdbeParameterIndex((Vdbe*)pStmt, zName, sqlite3Strlen30(zName));
+}
+
+/*
+** Transfer all bindings from the first statement over to the second.
+*/
+SQLITE_PRIVATE int sqlite3TransferBindings(sqlite3_stmt *pFromStmt, sqlite3_stmt *pToStmt){
+  Vdbe *pFrom = (Vdbe*)pFromStmt;
+  Vdbe *pTo = (Vdbe*)pToStmt;
+  int i;
+  assert( pTo->db==pFrom->db );
+  assert( pTo->nVar==pFrom->nVar );
+  sqlite3_mutex_enter(pTo->db->mutex);
+  for(i=0; i<pFrom->nVar; i++){
+    sqlite3VdbeMemMove(&pTo->aVar[i], &pFrom->aVar[i]);
+  }
+  sqlite3_mutex_leave(pTo->db->mutex);
+  return SQLITE_OK;
+}
+
+#ifndef SQLITE_OMIT_DEPRECATED
+/*
+** Deprecated external interface.  Internal/core SQLite code
+** should call sqlite3TransferBindings.
+**
+** It is misuse to call this routine with statements from different
+** database connections.  But as this is a deprecated interface, we
+** will not bother to check for that condition.
+**
+** If the two statements contain a different number of bindings, then
+** an SQLITE_ERROR is returned.  Nothing else can go wrong, so otherwise
+** SQLITE_OK is returned.
+*/
+SQLITE_API int sqlite3_transfer_bindings(sqlite3_stmt *pFromStmt, sqlite3_stmt *pToStmt){
+  Vdbe *pFrom = (Vdbe*)pFromStmt;
+  Vdbe *pTo = (Vdbe*)pToStmt;
+  if( pFrom->nVar!=pTo->nVar ){
+    return SQLITE_ERROR;
+  }
+  if( pTo->isPrepareV2 && pTo->expmask ){
+    pTo->expired = 1;
+  }
+  if( pFrom->isPrepareV2 && pFrom->expmask ){
+    pFrom->expired = 1;
+  }
+  return sqlite3TransferBindings(pFromStmt, pToStmt);
+}
+#endif
+
+/*
+** Return the sqlite3* database handle to which the prepared statement given
+** in the argument belongs.  This is the same database handle that was
+** the first argument to the sqlite3_prepare() that was used to create
+** the statement in the first place.
+*/
+SQLITE_API sqlite3 *sqlite3_db_handle(sqlite3_stmt *pStmt){
+  return pStmt ? ((Vdbe*)pStmt)->db : 0;
+}
+
+/*
+** Return true if the prepared statement is guaranteed to not modify the
+** database.
+*/
+SQLITE_API int sqlite3_stmt_readonly(sqlite3_stmt *pStmt){
+  return pStmt ? ((Vdbe*)pStmt)->readOnly : 1;
+}
+
+/*
+** Return true if the prepared statement is in need of being reset.
+*/
+SQLITE_API int sqlite3_stmt_busy(sqlite3_stmt *pStmt){
+  Vdbe *v = (Vdbe*)pStmt;
+  return v!=0 && v->magic==VDBE_MAGIC_RUN && v->pc>=0;
+}
+
+/*
+** Return a pointer to the next prepared statement after pStmt associated
+** with database connection pDb.  If pStmt is NULL, return the first
+** prepared statement for the database connection.  Return NULL if there
+** are no more.
+*/
+SQLITE_API sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt){
+  sqlite3_stmt *pNext;
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(pDb) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  sqlite3_mutex_enter(pDb->mutex);
+  if( pStmt==0 ){
+    pNext = (sqlite3_stmt*)pDb->pVdbe;
+  }else{
+    pNext = (sqlite3_stmt*)((Vdbe*)pStmt)->pNext;
+  }
+  sqlite3_mutex_leave(pDb->mutex);
+  return pNext;
+}
+
+/*
+** Return the value of a status counter for a prepared statement
+*/
+SQLITE_API int sqlite3_stmt_status(sqlite3_stmt *pStmt, int op, int resetFlag){
+  Vdbe *pVdbe = (Vdbe*)pStmt;
+  u32 v;
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !pStmt ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  v = pVdbe->aCounter[op];
+  if( resetFlag ) pVdbe->aCounter[op] = 0;
+  return (int)v;
+}
+
+/*
+** Return the SQL associated with a prepared statement
+*/
+SQLITE_API const char *sqlite3_sql(sqlite3_stmt *pStmt){
+  Vdbe *p = (Vdbe *)pStmt;
+  return p ? p->zSql : 0;
+}
+
+/*
+** Return the SQL associated with a prepared statement with
+** bound parameters expanded.  Space to hold the returned string is
+** obtained from sqlite3_malloc().  The caller is responsible for
+** freeing the returned string by passing it to sqlite3_free().
+**
+** The SQLITE_TRACE_SIZE_LIMIT puts an upper bound on the size of
+** expanded bound parameters.
+*/
+SQLITE_API char *sqlite3_expanded_sql(sqlite3_stmt *pStmt){
+#ifdef SQLITE_OMIT_TRACE
+  return 0;
+#else
+  char *z = 0;
+  const char *zSql = sqlite3_sql(pStmt);
+  if( zSql ){
+    Vdbe *p = (Vdbe *)pStmt;
+    sqlite3_mutex_enter(p->db->mutex);
+    z = sqlite3VdbeExpandSql(p, zSql);
+    sqlite3_mutex_leave(p->db->mutex);
+  }
+  return z;
+#endif
+}
+
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+/*
+** Allocate and populate an UnpackedRecord structure based on the serialized
+** record in nKey/pKey. Return a pointer to the new UnpackedRecord structure
+** if successful, or a NULL pointer if an OOM error is encountered.
+*/
+static UnpackedRecord *vdbeUnpackRecord(
+  KeyInfo *pKeyInfo, 
+  int nKey, 
+  const void *pKey
+){
+  char *dummy;                    /* Dummy argument for AllocUnpackedRecord() */
+  UnpackedRecord *pRet;           /* Return value */
+
+  pRet = sqlite3VdbeAllocUnpackedRecord(pKeyInfo, 0, 0, &dummy);
+  if( pRet ){
+    memset(pRet->aMem, 0, sizeof(Mem)*(pKeyInfo->nField+1));
+    sqlite3VdbeRecordUnpack(pKeyInfo, nKey, pKey, pRet);
+  }
+  return pRet;
+}
+
+/*
+** This function is called from within a pre-update callback to retrieve
+** a field of the row currently being updated or deleted.
+*/
+SQLITE_API int sqlite3_preupdate_old(sqlite3 *db, int iIdx, sqlite3_value **ppValue){
+  PreUpdate *p = db->pPreUpdate;
+  int rc = SQLITE_OK;
+
+  /* Test that this call is being made from within an SQLITE_DELETE or
+  ** SQLITE_UPDATE pre-update callback, and that iIdx is within range. */
+  if( !p || p->op==SQLITE_INSERT ){
+    rc = SQLITE_MISUSE_BKPT;
+    goto preupdate_old_out;
+  }
+  if( iIdx>=p->pCsr->nField || iIdx<0 ){
+    rc = SQLITE_RANGE;
+    goto preupdate_old_out;
+  }
+
+  /* If the old.* record has not yet been loaded into memory, do so now. */
+  if( p->pUnpacked==0 ){
+    u32 nRec;
+    u8 *aRec;
+
+    nRec = sqlite3BtreePayloadSize(p->pCsr->uc.pCursor);
+    aRec = sqlite3DbMallocRaw(db, nRec);
+    if( !aRec ) goto preupdate_old_out;
+    rc = sqlite3BtreeData(p->pCsr->uc.pCursor, 0, nRec, aRec);
+    if( rc==SQLITE_OK ){
+      p->pUnpacked = vdbeUnpackRecord(&p->keyinfo, nRec, aRec);
+      if( !p->pUnpacked ) rc = SQLITE_NOMEM;
+    }
+    if( rc!=SQLITE_OK ){
+      sqlite3DbFree(db, aRec);
+      goto preupdate_old_out;
+    }
+    p->aRecord = aRec;
+  }
+
+  if( iIdx>=p->pUnpacked->nField ){
+    *ppValue = (sqlite3_value *)columnNullValue();
+  }else{
+    Mem *pMem = *ppValue = &p->pUnpacked->aMem[iIdx];
+    *ppValue = &p->pUnpacked->aMem[iIdx];
+    if( iIdx==p->pTab->iPKey ){
+      sqlite3VdbeMemSetInt64(pMem, p->iKey1);
+    }else if( p->pTab->aCol[iIdx].affinity==SQLITE_AFF_REAL ){
+      if( pMem->flags & MEM_Int ){
+        sqlite3VdbeMemRealify(pMem);
+      }
+    }
+  }
+
+ preupdate_old_out:
+  sqlite3Error(db, rc);
+  return sqlite3ApiExit(db, rc);
+}
+#endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
+
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+/*
+** This function is called from within a pre-update callback to retrieve
+** the number of columns in the row being updated, deleted or inserted.
+*/
+SQLITE_API int sqlite3_preupdate_count(sqlite3 *db){
+  PreUpdate *p = db->pPreUpdate;
+  return (p ? p->keyinfo.nField : 0);
+}
+#endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
+
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+/*
+** This function is designed to be called from within a pre-update callback
+** only. It returns zero if the change that caused the callback was made
+** immediately by a user SQL statement. Or, if the change was made by a
+** trigger program, it returns the number of trigger programs currently
+** on the stack (1 for a top-level trigger, 2 for a trigger fired by a 
+** top-level trigger etc.).
+**
+** For the purposes of the previous paragraph, a foreign key CASCADE, SET NULL
+** or SET DEFAULT action is considered a trigger.
+*/
+SQLITE_API int sqlite3_preupdate_depth(sqlite3 *db){
+  PreUpdate *p = db->pPreUpdate;
+  return (p ? p->v->nFrame : 0);
+}
+#endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
+
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+/*
+** This function is called from within a pre-update callback to retrieve
+** a field of the row currently being updated or inserted.
+*/
+SQLITE_API int sqlite3_preupdate_new(sqlite3 *db, int iIdx, sqlite3_value **ppValue){
+  PreUpdate *p = db->pPreUpdate;
+  int rc = SQLITE_OK;
+  Mem *pMem;
+
+  if( !p || p->op==SQLITE_DELETE ){
+    rc = SQLITE_MISUSE_BKPT;
+    goto preupdate_new_out;
+  }
+  if( iIdx>=p->pCsr->nField || iIdx<0 ){
+    rc = SQLITE_RANGE;
+    goto preupdate_new_out;
+  }
+
+  if( p->op==SQLITE_INSERT ){
+    /* For an INSERT, memory cell p->iNewReg contains the serialized record
+    ** that is being inserted. Deserialize it. */
+    UnpackedRecord *pUnpack = p->pNewUnpacked;
+    if( !pUnpack ){
+      Mem *pData = &p->v->aMem[p->iNewReg];
+      rc = ExpandBlob(pData);
+      if( rc!=SQLITE_OK ) goto preupdate_new_out;
+      pUnpack = vdbeUnpackRecord(&p->keyinfo, pData->n, pData->z);
+      if( !pUnpack ){
+        rc = SQLITE_NOMEM;
+        goto preupdate_new_out;
+      }
+      p->pNewUnpacked = pUnpack;
+    }
+    if( iIdx>=pUnpack->nField ){
+      pMem = (sqlite3_value *)columnNullValue();
+    }else{
+      pMem = &pUnpack->aMem[iIdx];
+      if( iIdx==p->pTab->iPKey ){
+        sqlite3VdbeMemSetInt64(pMem, p->iKey2);
+      }
+    }
+  }else{
+    /* For an UPDATE, memory cell (p->iNewReg+1+iIdx) contains the required
+    ** value. Make a copy of the cell contents and return a pointer to it.
+    ** It is not safe to return a pointer to the memory cell itself as the
+    ** caller may modify the value text encoding.
+    */
+    assert( p->op==SQLITE_UPDATE );
+    if( !p->aNew ){
+      p->aNew = (Mem *)sqlite3DbMallocZero(db, sizeof(Mem) * p->pCsr->nField);
+      if( !p->aNew ){
+        rc = SQLITE_NOMEM;
+        goto preupdate_new_out;
+      }
+    }
+    assert( iIdx>=0 && iIdx<p->pCsr->nField );
+    pMem = &p->aNew[iIdx];
+    if( pMem->flags==0 ){
+      if( iIdx==p->pTab->iPKey ){
+        sqlite3VdbeMemSetInt64(pMem, p->iKey2);
+      }else{
+        rc = sqlite3VdbeMemCopy(pMem, &p->v->aMem[p->iNewReg+1+iIdx]);
+        if( rc!=SQLITE_OK ) goto preupdate_new_out;
+      }
+    }
+  }
+  *ppValue = pMem;
+
+ preupdate_new_out:
+  sqlite3Error(db, rc);
+  return sqlite3ApiExit(db, rc);
+}
+#endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
+
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+/*
+** Return status data for a single loop within query pStmt.
+*/
+SQLITE_API int sqlite3_stmt_scanstatus(
+  sqlite3_stmt *pStmt,            /* Prepared statement being queried */
+  int idx,                        /* Index of loop to report on */
+  int iScanStatusOp,              /* Which metric to return */
+  void *pOut                      /* OUT: Write the answer here */
+){
+  Vdbe *p = (Vdbe*)pStmt;
+  ScanStatus *pScan;
+  if( idx<0 || idx>=p->nScan ) return 1;
+  pScan = &p->aScan[idx];
+  switch( iScanStatusOp ){
+    case SQLITE_SCANSTAT_NLOOP: {
+      *(sqlite3_int64*)pOut = p->anExec[pScan->addrLoop];
+      break;
+    }
+    case SQLITE_SCANSTAT_NVISIT: {
+      *(sqlite3_int64*)pOut = p->anExec[pScan->addrVisit];
+      break;
+    }
+    case SQLITE_SCANSTAT_EST: {
+      double r = 1.0;
+      LogEst x = pScan->nEst;
+      while( x<100 ){
+        x += 10;
+        r *= 0.5;
+      }
+      *(double*)pOut = r*sqlite3LogEstToInt(x);
+      break;
+    }
+    case SQLITE_SCANSTAT_NAME: {
+      *(const char**)pOut = pScan->zName;
+      break;
+    }
+    case SQLITE_SCANSTAT_EXPLAIN: {
+      if( pScan->addrExplain ){
+        *(const char**)pOut = p->aOp[ pScan->addrExplain ].p4.z;
+      }else{
+        *(const char**)pOut = 0;
+      }
+      break;
+    }
+    case SQLITE_SCANSTAT_SELECTID: {
+      if( pScan->addrExplain ){
+        *(int*)pOut = p->aOp[ pScan->addrExplain ].p1;
+      }else{
+        *(int*)pOut = -1;
+      }
+      break;
+    }
+    default: {
+      return 1;
+    }
+  }
+  return 0;
+}
+
+/*
+** Zero all counters associated with the sqlite3_stmt_scanstatus() data.
+*/
+SQLITE_API void sqlite3_stmt_scanstatus_reset(sqlite3_stmt *pStmt){
+  Vdbe *p = (Vdbe*)pStmt;
+  memset(p->anExec, 0, p->nOp * sizeof(i64));
+}
+#endif /* SQLITE_ENABLE_STMT_SCANSTATUS */
+
+/************** End of vdbeapi.c *********************************************/
+/************** Begin file vdbetrace.c ***************************************/
+/*
+** 2009 November 25
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains code used to insert the values of host parameters
+** (aka "wildcards") into the SQL text output by sqlite3_trace().
+**
+** The Vdbe parse-tree explainer is also found here.
+*/
+/* #include "sqliteInt.h" */
+/* #include "vdbeInt.h" */
+
+#ifndef SQLITE_OMIT_TRACE
+
+/*
+** zSql is a zero-terminated string of UTF-8 SQL text.  Return the number of
+** bytes in this text up to but excluding the first character in
+** a host parameter.  If the text contains no host parameters, return
+** the total number of bytes in the text.
+*/
+static int findNextHostParameter(const char *zSql, int *pnToken){
+  int tokenType;
+  int nTotal = 0;
+  int n;
+
+  *pnToken = 0;
+  while( zSql[0] ){
+    n = sqlite3GetToken((u8*)zSql, &tokenType);
+    assert( n>0 && tokenType!=TK_ILLEGAL );
+    if( tokenType==TK_VARIABLE ){
+      *pnToken = n;
+      break;
+    }
+    nTotal += n;
+    zSql += n;
+  }
+  return nTotal;
+}
+
+/*
+** This function returns a pointer to a nul-terminated string in memory
+** obtained from sqlite3DbMalloc(). If sqlite3.nVdbeExec is 1, then the
+** string contains a copy of zRawSql but with host parameters expanded to 
+** their current bindings. Or, if sqlite3.nVdbeExec is greater than 1, 
+** then the returned string holds a copy of zRawSql with "-- " prepended
+** to each line of text.
+**
+** If the SQLITE_TRACE_SIZE_LIMIT macro is defined to an integer, then
+** then long strings and blobs are truncated to that many bytes.  This
+** can be used to prevent unreasonably large trace strings when dealing
+** with large (multi-megabyte) strings and blobs.
+**
+** The calling function is responsible for making sure the memory returned
+** is eventually freed.
+**
+** ALGORITHM:  Scan the input string looking for host parameters in any of
+** these forms:  ?, ?N, $A, @A, :A.  Take care to avoid text within
+** string literals, quoted identifier names, and comments.  For text forms,
+** the host parameter index is found by scanning the prepared
+** statement for the corresponding OP_Variable opcode.  Once the host
+** parameter index is known, locate the value in p->aVar[].  Then render
+** the value as a literal in place of the host parameter name.
+*/
+SQLITE_PRIVATE char *sqlite3VdbeExpandSql(
+  Vdbe *p,                 /* The prepared statement being evaluated */
+  const char *zRawSql      /* Raw text of the SQL statement */
+){
+  sqlite3 *db;             /* The database connection */
+  int idx = 0;             /* Index of a host parameter */
+  int nextIndex = 1;       /* Index of next ? host parameter */
+  int n;                   /* Length of a token prefix */
+  int nToken;              /* Length of the parameter token */
+  int i;                   /* Loop counter */
+  Mem *pVar;               /* Value of a host parameter */
+  StrAccum out;            /* Accumulate the output here */
+#ifndef SQLITE_OMIT_UTF16
+  Mem utf8;                /* Used to convert UTF16 parameters into UTF8 for display */
+#endif
+  char zBase[100];         /* Initial working space */
+
+  db = p->db;
+  sqlite3StrAccumInit(&out, 0, zBase, sizeof(zBase), 
+                      db->aLimit[SQLITE_LIMIT_LENGTH]);
+  if( db->nVdbeExec>1 ){
+    while( *zRawSql ){
+      const char *zStart = zRawSql;
+      while( *(zRawSql++)!='\n' && *zRawSql );
+      sqlite3StrAccumAppend(&out, "-- ", 3);
+      assert( (zRawSql - zStart) > 0 );
+      sqlite3StrAccumAppend(&out, zStart, (int)(zRawSql-zStart));
+    }
+  }else if( p->nVar==0 ){
+    sqlite3StrAccumAppend(&out, zRawSql, sqlite3Strlen30(zRawSql));
+  }else{
+    while( zRawSql[0] ){
+      n = findNextHostParameter(zRawSql, &nToken);
+      assert( n>0 );
+      sqlite3StrAccumAppend(&out, zRawSql, n);
+      zRawSql += n;
+      assert( zRawSql[0] || nToken==0 );
+      if( nToken==0 ) break;
+      if( zRawSql[0]=='?' ){
+        if( nToken>1 ){
+          assert( sqlite3Isdigit(zRawSql[1]) );
+          sqlite3GetInt32(&zRawSql[1], &idx);
+        }else{
+          idx = nextIndex;
+        }
+      }else{
+        assert( zRawSql[0]==':' || zRawSql[0]=='$' ||
+                zRawSql[0]=='@' || zRawSql[0]=='#' );
+        testcase( zRawSql[0]==':' );
+        testcase( zRawSql[0]=='$' );
+        testcase( zRawSql[0]=='@' );
+        testcase( zRawSql[0]=='#' );
+        idx = sqlite3VdbeParameterIndex(p, zRawSql, nToken);
+        assert( idx>0 );
+      }
+      zRawSql += nToken;
+      nextIndex = idx + 1;
+      assert( idx>0 && idx<=p->nVar );
+      pVar = &p->aVar[idx-1];
+      if( pVar->flags & MEM_Null ){
+        sqlite3StrAccumAppend(&out, "NULL", 4);
+      }else if( pVar->flags & MEM_Int ){
+        sqlite3XPrintf(&out, "%lld", pVar->u.i);
+      }else if( pVar->flags & MEM_Real ){
+        sqlite3XPrintf(&out, "%!.15g", pVar->u.r);
+      }else if( pVar->flags & MEM_Str ){
+        int nOut;  /* Number of bytes of the string text to include in output */
+#ifndef SQLITE_OMIT_UTF16
+        u8 enc = ENC(db);
+        if( enc!=SQLITE_UTF8 ){
+          memset(&utf8, 0, sizeof(utf8));
+          utf8.db = db;
+          sqlite3VdbeMemSetStr(&utf8, pVar->z, pVar->n, enc, SQLITE_STATIC);
+          if( SQLITE_NOMEM==sqlite3VdbeChangeEncoding(&utf8, SQLITE_UTF8) ){
+            out.accError = STRACCUM_NOMEM;
+            out.nAlloc = 0;
+          }
+          pVar = &utf8;
+        }
+#endif
+        nOut = pVar->n;
+#ifdef SQLITE_TRACE_SIZE_LIMIT
+        if( nOut>SQLITE_TRACE_SIZE_LIMIT ){
+          nOut = SQLITE_TRACE_SIZE_LIMIT;
+          while( nOut<pVar->n && (pVar->z[nOut]&0xc0)==0x80 ){ nOut++; }
+        }
+#endif    
+        sqlite3XPrintf(&out, "'%.*q'", nOut, pVar->z);
+#ifdef SQLITE_TRACE_SIZE_LIMIT
+        if( nOut<pVar->n ){
+          sqlite3XPrintf(&out, "/*+%d bytes*/", pVar->n-nOut);
+        }
+#endif
+#ifndef SQLITE_OMIT_UTF16
+        if( enc!=SQLITE_UTF8 ) sqlite3VdbeMemRelease(&utf8);
+#endif
+      }else if( pVar->flags & MEM_Zero ){
+        sqlite3XPrintf(&out, "zeroblob(%d)", pVar->u.nZero);
+      }else{
+        int nOut;  /* Number of bytes of the blob to include in output */
+        assert( pVar->flags & MEM_Blob );
+        sqlite3StrAccumAppend(&out, "x'", 2);
+        nOut = pVar->n;
+#ifdef SQLITE_TRACE_SIZE_LIMIT
+        if( nOut>SQLITE_TRACE_SIZE_LIMIT ) nOut = SQLITE_TRACE_SIZE_LIMIT;
+#endif
+        for(i=0; i<nOut; i++){
+          sqlite3XPrintf(&out, "%02x", pVar->z[i]&0xff);
+        }
+        sqlite3StrAccumAppend(&out, "'", 1);
+#ifdef SQLITE_TRACE_SIZE_LIMIT
+        if( nOut<pVar->n ){
+          sqlite3XPrintf(&out, "/*+%d bytes*/", pVar->n-nOut);
+        }
+#endif
+      }
+    }
+  }
+  if( out.accError ) sqlite3StrAccumReset(&out);
+  return sqlite3StrAccumFinish(&out);
+}
+
+#endif /* #ifndef SQLITE_OMIT_TRACE */
+
+/************** End of vdbetrace.c *******************************************/
+/************** Begin file vdbe.c ********************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** The code in this file implements the function that runs the
+** bytecode of a prepared statement.
+**
+** Various scripts scan this source file in order to generate HTML
+** documentation, headers files, or other derived files.  The formatting
+** of the code in this file is, therefore, important.  See other comments
+** in this file for details.  If in doubt, do not deviate from existing
+** commenting and indentation practices when changing or adding code.
+*/
+/* #include "sqliteInt.h" */
+/* #include "vdbeInt.h" */
+
+/*
+** Invoke this macro on memory cells just prior to changing the
+** value of the cell.  This macro verifies that shallow copies are
+** not misused.  A shallow copy of a string or blob just copies a
+** pointer to the string or blob, not the content.  If the original
+** is changed while the copy is still in use, the string or blob might
+** be changed out from under the copy.  This macro verifies that nothing
+** like that ever happens.
+*/
+#ifdef SQLITE_DEBUG
+# define memAboutToChange(P,M) sqlite3VdbeMemAboutToChange(P,M)
+#else
+# define memAboutToChange(P,M)
+#endif
+
+/*
+** The following global variable is incremented every time a cursor
+** moves, either by the OP_SeekXX, OP_Next, or OP_Prev opcodes.  The test
+** procedures use this information to make sure that indices are
+** working correctly.  This variable has no function other than to
+** help verify the correct operation of the library.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_search_count = 0;
+#endif
+
+/*
+** When this global variable is positive, it gets decremented once before
+** each instruction in the VDBE.  When it reaches zero, the u1.isInterrupted
+** field of the sqlite3 structure is set in order to simulate an interrupt.
+**
+** This facility is used for testing purposes only.  It does not function
+** in an ordinary build.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_interrupt_count = 0;
+#endif
+
+/*
+** The next global variable is incremented each type the OP_Sort opcode
+** is executed.  The test procedures use this information to make sure that
+** sorting is occurring or not occurring at appropriate times.   This variable
+** has no function other than to help verify the correct operation of the
+** library.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_sort_count = 0;
+#endif
+
+/*
+** The next global variable records the size of the largest MEM_Blob
+** or MEM_Str that has been used by a VDBE opcode.  The test procedures
+** use this information to make sure that the zero-blob functionality
+** is working correctly.   This variable has no function other than to
+** help verify the correct operation of the library.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_max_blobsize = 0;
+static void updateMaxBlobsize(Mem *p){
+  if( (p->flags & (MEM_Str|MEM_Blob))!=0 && p->n>sqlite3_max_blobsize ){
+    sqlite3_max_blobsize = p->n;
+  }
+}
+#endif
+
+/*
+** This macro evaluates to true if either the update hook or the preupdate
+** hook are enabled for database connect DB.
+*/
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+# define HAS_UPDATE_HOOK(DB) ((DB)->xPreUpdateCallback||(DB)->xUpdateCallback)
+#else
+# define HAS_UPDATE_HOOK(DB) ((DB)->xUpdateCallback)
+#endif
+
+/*
+** The next global variable is incremented each time the OP_Found opcode
+** is executed. This is used to test whether or not the foreign key
+** operation implemented using OP_FkIsZero is working. This variable
+** has no function other than to help verify the correct operation of the
+** library.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_found_count = 0;
+#endif
+
+/*
+** Test a register to see if it exceeds the current maximum blob size.
+** If it does, record the new maximum blob size.
+*/
+#if defined(SQLITE_TEST) && !defined(SQLITE_OMIT_BUILTIN_TEST)
+# define UPDATE_MAX_BLOBSIZE(P)  updateMaxBlobsize(P)
+#else
+# define UPDATE_MAX_BLOBSIZE(P)
+#endif
+
+/*
+** Invoke the VDBE coverage callback, if that callback is defined.  This
+** feature is used for test suite validation only and does not appear an
+** production builds.
+**
+** M is an integer, 2 or 3, that indices how many different ways the
+** branch can go.  It is usually 2.  "I" is the direction the branch
+** goes.  0 means falls through.  1 means branch is taken.  2 means the
+** second alternative branch is taken.
+**
+** iSrcLine is the source code line (from the __LINE__ macro) that
+** generated the VDBE instruction.  This instrumentation assumes that all
+** source code is in a single file (the amalgamation).  Special values 1
+** and 2 for the iSrcLine parameter mean that this particular branch is
+** always taken or never taken, respectively.
+*/
+#if !defined(SQLITE_VDBE_COVERAGE)
+# define VdbeBranchTaken(I,M)
+#else
+# define VdbeBranchTaken(I,M) vdbeTakeBranch(pOp->iSrcLine,I,M)
+  static void vdbeTakeBranch(int iSrcLine, u8 I, u8 M){
+    if( iSrcLine<=2 && ALWAYS(iSrcLine>0) ){
+      M = iSrcLine;
+      /* Assert the truth of VdbeCoverageAlwaysTaken() and 
+      ** VdbeCoverageNeverTaken() */
+      assert( (M & I)==I );
+    }else{
+      if( sqlite3GlobalConfig.xVdbeBranch==0 ) return;  /*NO_TEST*/
+      sqlite3GlobalConfig.xVdbeBranch(sqlite3GlobalConfig.pVdbeBranchArg,
+                                      iSrcLine,I,M);
+    }
+  }
+#endif
+
+/*
+** Convert the given register into a string if it isn't one
+** already. Return non-zero if a malloc() fails.
+*/
+#define Stringify(P, enc) \
+   if(((P)->flags&(MEM_Str|MEM_Blob))==0 && sqlite3VdbeMemStringify(P,enc,0)) \
+     { goto no_mem; }
+
+/*
+** An ephemeral string value (signified by the MEM_Ephem flag) contains
+** a pointer to a dynamically allocated string where some other entity
+** is responsible for deallocating that string.  Because the register
+** does not control the string, it might be deleted without the register
+** knowing it.
+**
+** This routine converts an ephemeral string into a dynamically allocated
+** string that the register itself controls.  In other words, it
+** converts an MEM_Ephem string into a string with P.z==P.zMalloc.
+*/
+#define Deephemeralize(P) \
+   if( ((P)->flags&MEM_Ephem)!=0 \
+       && sqlite3VdbeMemMakeWriteable(P) ){ goto no_mem;}
+
+/* Return true if the cursor was opened using the OP_OpenSorter opcode. */
+#define isSorter(x) ((x)->eCurType==CURTYPE_SORTER)
+
+/*
+** Allocate VdbeCursor number iCur.  Return a pointer to it.  Return NULL
+** if we run out of memory.
+*/
+static VdbeCursor *allocateCursor(
+  Vdbe *p,              /* The virtual machine */
+  int iCur,             /* Index of the new VdbeCursor */
+  int nField,           /* Number of fields in the table or index */
+  int iDb,              /* Database the cursor belongs to, or -1 */
+  u8 eCurType           /* Type of the new cursor */
+){
+  /* Find the memory cell that will be used to store the blob of memory
+  ** required for this VdbeCursor structure. It is convenient to use a 
+  ** vdbe memory cell to manage the memory allocation required for a
+  ** VdbeCursor structure for the following reasons:
+  **
+  **   * Sometimes cursor numbers are used for a couple of different
+  **     purposes in a vdbe program. The different uses might require
+  **     different sized allocations. Memory cells provide growable
+  **     allocations.
+  **
+  **   * When using ENABLE_MEMORY_MANAGEMENT, memory cell buffers can
+  **     be freed lazily via the sqlite3_release_memory() API. This
+  **     minimizes the number of malloc calls made by the system.
+  **
+  ** The memory cell for cursor 0 is aMem[0]. The rest are allocated from
+  ** the top of the register space.  Cursor 1 is at Mem[p->nMem-1].
+  ** Cursor 2 is at Mem[p->nMem-2]. And so forth.
+  */
+  Mem *pMem = iCur>0 ? &p->aMem[p->nMem-iCur] : p->aMem;
+
+  int nByte;
+  VdbeCursor *pCx = 0;
+  nByte = 
+      ROUND8(sizeof(VdbeCursor)) + 2*sizeof(u32)*nField + 
+      (eCurType==CURTYPE_BTREE?sqlite3BtreeCursorSize():0);
+
+  assert( iCur>=0 && iCur<p->nCursor );
+  if( p->apCsr[iCur] ){ /*OPTIMIZATION-IF-FALSE*/
+    sqlite3VdbeFreeCursor(p, p->apCsr[iCur]);
+    p->apCsr[iCur] = 0;
+  }
+  if( SQLITE_OK==sqlite3VdbeMemClearAndResize(pMem, nByte) ){
+    p->apCsr[iCur] = pCx = (VdbeCursor*)pMem->z;
+    memset(pCx, 0, sizeof(VdbeCursor));
+    pCx->eCurType = eCurType;
+    pCx->iDb = iDb;
+    pCx->nField = nField;
+    pCx->aOffset = &pCx->aType[nField];
+    if( eCurType==CURTYPE_BTREE ){
+      pCx->uc.pCursor = (BtCursor*)
+          &pMem->z[ROUND8(sizeof(VdbeCursor))+2*sizeof(u32)*nField];
+      sqlite3BtreeCursorZero(pCx->uc.pCursor);
+    }
+  }
+  return pCx;
+}
+
+/*
+** Try to convert a value into a numeric representation if we can
+** do so without loss of information.  In other words, if the string
+** looks like a number, convert it into a number.  If it does not
+** look like a number, leave it alone.
+**
+** If the bTryForInt flag is true, then extra effort is made to give
+** an integer representation.  Strings that look like floating point
+** values but which have no fractional component (example: '48.00')
+** will have a MEM_Int representation when bTryForInt is true.
+**
+** If bTryForInt is false, then if the input string contains a decimal
+** point or exponential notation, the result is only MEM_Real, even
+** if there is an exact integer representation of the quantity.
+*/
+static void applyNumericAffinity(Mem *pRec, int bTryForInt){
+  double rValue;
+  i64 iValue;
+  u8 enc = pRec->enc;
+  assert( (pRec->flags & (MEM_Str|MEM_Int|MEM_Real))==MEM_Str );
+  if( sqlite3AtoF(pRec->z, &rValue, pRec->n, enc)==0 ) return;
+  if( 0==sqlite3Atoi64(pRec->z, &iValue, pRec->n, enc) ){
+    pRec->u.i = iValue;
+    pRec->flags |= MEM_Int;
+  }else{
+    pRec->u.r = rValue;
+    pRec->flags |= MEM_Real;
+    if( bTryForInt ) sqlite3VdbeIntegerAffinity(pRec);
+  }
+}
+
+/*
+** Processing is determine by the affinity parameter:
+**
+** SQLITE_AFF_INTEGER:
+** SQLITE_AFF_REAL:
+** SQLITE_AFF_NUMERIC:
+**    Try to convert pRec to an integer representation or a 
+**    floating-point representation if an integer representation
+**    is not possible.  Note that the integer representation is
+**    always preferred, even if the affinity is REAL, because
+**    an integer representation is more space efficient on disk.
+**
+** SQLITE_AFF_TEXT:
+**    Convert pRec to a text representation.
+**
+** SQLITE_AFF_BLOB:
+**    No-op.  pRec is unchanged.
+*/
+static void applyAffinity(
+  Mem *pRec,          /* The value to apply affinity to */
+  char affinity,      /* The affinity to be applied */
+  u8 enc              /* Use this text encoding */
+){
+  if( affinity>=SQLITE_AFF_NUMERIC ){
+    assert( affinity==SQLITE_AFF_INTEGER || affinity==SQLITE_AFF_REAL
+             || affinity==SQLITE_AFF_NUMERIC );
+    if( (pRec->flags & MEM_Int)==0 ){ /*OPTIMIZATION-IF-FALSE*/
+      if( (pRec->flags & MEM_Real)==0 ){
+        if( pRec->flags & MEM_Str ) applyNumericAffinity(pRec,1);
+      }else{
+        sqlite3VdbeIntegerAffinity(pRec);
+      }
+    }
+  }else if( affinity==SQLITE_AFF_TEXT ){
+    /* Only attempt the conversion to TEXT if there is an integer or real
+    ** representation (blob and NULL do not get converted) but no string
+    ** representation.  It would be harmless to repeat the conversion if 
+    ** there is already a string rep, but it is pointless to waste those
+    ** CPU cycles. */
+    if( 0==(pRec->flags&MEM_Str) ){ /*OPTIMIZATION-IF-FALSE*/
+      if( (pRec->flags&(MEM_Real|MEM_Int)) ){
+        sqlite3VdbeMemStringify(pRec, enc, 1);
+      }
+    }
+    pRec->flags &= ~(MEM_Real|MEM_Int);
+  }
+}
+
+/*
+** Try to convert the type of a function argument or a result column
+** into a numeric representation.  Use either INTEGER or REAL whichever
+** is appropriate.  But only do the conversion if it is possible without
+** loss of information and return the revised type of the argument.
+*/
+SQLITE_API int sqlite3_value_numeric_type(sqlite3_value *pVal){
+  int eType = sqlite3_value_type(pVal);
+  if( eType==SQLITE_TEXT ){
+    Mem *pMem = (Mem*)pVal;
+    applyNumericAffinity(pMem, 0);
+    eType = sqlite3_value_type(pVal);
+  }
+  return eType;
+}
+
+/*
+** Exported version of applyAffinity(). This one works on sqlite3_value*, 
+** not the internal Mem* type.
+*/
+SQLITE_PRIVATE void sqlite3ValueApplyAffinity(
+  sqlite3_value *pVal, 
+  u8 affinity, 
+  u8 enc
+){
+  applyAffinity((Mem *)pVal, affinity, enc);
+}
+
+/*
+** pMem currently only holds a string type (or maybe a BLOB that we can
+** interpret as a string if we want to).  Compute its corresponding
+** numeric type, if has one.  Set the pMem->u.r and pMem->u.i fields
+** accordingly.
+*/
+static u16 SQLITE_NOINLINE computeNumericType(Mem *pMem){
+  assert( (pMem->flags & (MEM_Int|MEM_Real))==0 );
+  assert( (pMem->flags & (MEM_Str|MEM_Blob))!=0 );
+  if( sqlite3AtoF(pMem->z, &pMem->u.r, pMem->n, pMem->enc)==0 ){
+    return 0;
+  }
+  if( sqlite3Atoi64(pMem->z, &pMem->u.i, pMem->n, pMem->enc)==SQLITE_OK ){
+    return MEM_Int;
+  }
+  return MEM_Real;
+}
+
+/*
+** Return the numeric type for pMem, either MEM_Int or MEM_Real or both or
+** none.  
+**
+** Unlike applyNumericAffinity(), this routine does not modify pMem->flags.
+** But it does set pMem->u.r and pMem->u.i appropriately.
+*/
+static u16 numericType(Mem *pMem){
+  if( pMem->flags & (MEM_Int|MEM_Real) ){
+    return pMem->flags & (MEM_Int|MEM_Real);
+  }
+  if( pMem->flags & (MEM_Str|MEM_Blob) ){
+    return computeNumericType(pMem);
+  }
+  return 0;
+}
+
+#ifdef SQLITE_DEBUG
+/*
+** Write a nice string representation of the contents of cell pMem
+** into buffer zBuf, length nBuf.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemPrettyPrint(Mem *pMem, char *zBuf){
+  char *zCsr = zBuf;
+  int f = pMem->flags;
+
+  static const char *const encnames[] = {"(X)", "(8)", "(16LE)", "(16BE)"};
+
+  if( f&MEM_Blob ){
+    int i;
+    char c;
+    if( f & MEM_Dyn ){
+      c = 'z';
+      assert( (f & (MEM_Static|MEM_Ephem))==0 );
+    }else if( f & MEM_Static ){
+      c = 't';
+      assert( (f & (MEM_Dyn|MEM_Ephem))==0 );
+    }else if( f & MEM_Ephem ){
+      c = 'e';
+      assert( (f & (MEM_Static|MEM_Dyn))==0 );
+    }else{
+      c = 's';
+    }
+
+    sqlite3_snprintf(100, zCsr, "%c", c);
+    zCsr += sqlite3Strlen30(zCsr);
+    sqlite3_snprintf(100, zCsr, "%d[", pMem->n);
+    zCsr += sqlite3Strlen30(zCsr);
+    for(i=0; i<16 && i<pMem->n; i++){
+      sqlite3_snprintf(100, zCsr, "%02X", ((int)pMem->z[i] & 0xFF));
+      zCsr += sqlite3Strlen30(zCsr);
+    }
+    for(i=0; i<16 && i<pMem->n; i++){
+      char z = pMem->z[i];
+      if( z<32 || z>126 ) *zCsr++ = '.';
+      else *zCsr++ = z;
+    }
+
+    sqlite3_snprintf(100, zCsr, "]%s", encnames[pMem->enc]);
+    zCsr += sqlite3Strlen30(zCsr);
+    if( f & MEM_Zero ){
+      sqlite3_snprintf(100, zCsr,"+%dz",pMem->u.nZero);
+      zCsr += sqlite3Strlen30(zCsr);
+    }
+    *zCsr = '\0';
+  }else if( f & MEM_Str ){
+    int j, k;
+    zBuf[0] = ' ';
+    if( f & MEM_Dyn ){
+      zBuf[1] = 'z';
+      assert( (f & (MEM_Static|MEM_Ephem))==0 );
+    }else if( f & MEM_Static ){
+      zBuf[1] = 't';
+      assert( (f & (MEM_Dyn|MEM_Ephem))==0 );
+    }else if( f & MEM_Ephem ){
+      zBuf[1] = 'e';
+      assert( (f & (MEM_Static|MEM_Dyn))==0 );
+    }else{
+      zBuf[1] = 's';
+    }
+    k = 2;
+    sqlite3_snprintf(100, &zBuf[k], "%d", pMem->n);
+    k += sqlite3Strlen30(&zBuf[k]);
+    zBuf[k++] = '[';
+    for(j=0; j<15 && j<pMem->n; j++){
+      u8 c = pMem->z[j];
+      if( c>=0x20 && c<0x7f ){
+        zBuf[k++] = c;
+      }else{
+        zBuf[k++] = '.';
+      }
+    }
+    zBuf[k++] = ']';
+    sqlite3_snprintf(100,&zBuf[k], encnames[pMem->enc]);
+    k += sqlite3Strlen30(&zBuf[k]);
+    zBuf[k++] = 0;
+  }
+}
+#endif
+
+#ifdef SQLITE_DEBUG
+/*
+** Print the value of a register for tracing purposes:
+*/
+static void memTracePrint(Mem *p){
+  if( p->flags & MEM_Undefined ){
+    printf(" undefined");
+  }else if( p->flags & MEM_Null ){
+    printf(" NULL");
+  }else if( (p->flags & (MEM_Int|MEM_Str))==(MEM_Int|MEM_Str) ){
+    printf(" si:%lld", p->u.i);
+  }else if( p->flags & MEM_Int ){
+    printf(" i:%lld", p->u.i);
+#ifndef SQLITE_OMIT_FLOATING_POINT
+  }else if( p->flags & MEM_Real ){
+    printf(" r:%g", p->u.r);
+#endif
+  }else if( p->flags & MEM_RowSet ){
+    printf(" (rowset)");
+  }else{
+    char zBuf[200];
+    sqlite3VdbeMemPrettyPrint(p, zBuf);
+    printf(" %s", zBuf);
+  }
+  if( p->flags & MEM_Subtype ) printf(" subtype=0x%02x", p->eSubtype);
+}
+static void registerTrace(int iReg, Mem *p){
+  printf("REG[%d] = ", iReg);
+  memTracePrint(p);
+  printf("\n");
+}
+#endif
+
+#ifdef SQLITE_DEBUG
+#  define REGISTER_TRACE(R,M) if(db->flags&SQLITE_VdbeTrace)registerTrace(R,M)
+#else
+#  define REGISTER_TRACE(R,M)
+#endif
+
+
+#ifdef VDBE_PROFILE
+
+/* 
+** hwtime.h contains inline assembler code for implementing 
+** high-performance timing routines.
+*/
+/************** Include hwtime.h in the middle of vdbe.c *********************/
+/************** Begin file hwtime.h ******************************************/
+/*
+** 2008 May 27
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains inline asm code for retrieving "high-performance"
+** counters for x86 class CPUs.
+*/
+#ifndef SQLITE_HWTIME_H
+#define SQLITE_HWTIME_H
+
+/*
+** The following routine only works on pentium-class (or newer) processors.
+** It uses the RDTSC opcode to read the cycle count value out of the
+** processor and returns that value.  This can be used for high-res
+** profiling.
+*/
+#if (defined(__GNUC__) || defined(_MSC_VER)) && \
+      (defined(i386) || defined(__i386__) || defined(_M_IX86))
+
+  #if defined(__GNUC__)
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+     unsigned int lo, hi;
+     __asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
+     return (sqlite_uint64)hi << 32 | lo;
+  }
+
+  #elif defined(_MSC_VER)
+
+  __declspec(naked) __inline sqlite_uint64 __cdecl sqlite3Hwtime(void){
+     __asm {
+        rdtsc
+        ret       ; return value at EDX:EAX
+     }
+  }
+
+  #endif
+
+#elif (defined(__GNUC__) && defined(__x86_64__))
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+      unsigned long val;
+      __asm__ __volatile__ ("rdtsc" : "=A" (val));
+      return val;
+  }
+ 
+#elif (defined(__GNUC__) && defined(__ppc__))
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+      unsigned long long retval;
+      unsigned long junk;
+      __asm__ __volatile__ ("\n\
+          1:      mftbu   %1\n\
+                  mftb    %L0\n\
+                  mftbu   %0\n\
+                  cmpw    %0,%1\n\
+                  bne     1b"
+                  : "=r" (retval), "=r" (junk));
+      return retval;
+  }
+
+#else
+
+  #error Need implementation of sqlite3Hwtime() for your platform.
+
+  /*
+  ** To compile without implementing sqlite3Hwtime() for your platform,
+  ** you can remove the above #error and use the following
+  ** stub function.  You will lose timing support for many
+  ** of the debugging and testing utilities, but it should at
+  ** least compile and run.
+  */
+SQLITE_PRIVATE   sqlite_uint64 sqlite3Hwtime(void){ return ((sqlite_uint64)0); }
+
+#endif
+
+#endif /* !defined(SQLITE_HWTIME_H) */
+
+/************** End of hwtime.h **********************************************/
+/************** Continuing where we left off in vdbe.c ***********************/
+
+#endif
+
+#ifndef NDEBUG
+/*
+** This function is only called from within an assert() expression. It
+** checks that the sqlite3.nTransaction variable is correctly set to
+** the number of non-transaction savepoints currently in the 
+** linked list starting at sqlite3.pSavepoint.
+** 
+** Usage:
+**
+**     assert( checkSavepointCount(db) );
+*/
+static int checkSavepointCount(sqlite3 *db){
+  int n = 0;
+  Savepoint *p;
+  for(p=db->pSavepoint; p; p=p->pNext) n++;
+  assert( n==(db->nSavepoint + db->isTransactionSavepoint) );
+  return 1;
+}
+#endif
+
+/*
+** Return the register of pOp->p2 after first preparing it to be
+** overwritten with an integer value.
+*/
+static SQLITE_NOINLINE Mem *out2PrereleaseWithClear(Mem *pOut){
+  sqlite3VdbeMemSetNull(pOut);
+  pOut->flags = MEM_Int;
+  return pOut;
+}
+static Mem *out2Prerelease(Vdbe *p, VdbeOp *pOp){
+  Mem *pOut;
+  assert( pOp->p2>0 );
+  assert( pOp->p2<=(p->nMem+1 - p->nCursor) );
+  pOut = &p->aMem[pOp->p2];
+  memAboutToChange(p, pOut);
+  if( VdbeMemDynamic(pOut) ){ /*OPTIMIZATION-IF-FALSE*/
+    return out2PrereleaseWithClear(pOut);
+  }else{
+    pOut->flags = MEM_Int;
+    return pOut;
+  }
+}
+
+
+/*
+** Execute as much of a VDBE program as we can.
+** This is the core of sqlite3_step().  
+*/
+SQLITE_PRIVATE int sqlite3VdbeExec(
+  Vdbe *p                    /* The VDBE */
+){
+  Op *aOp = p->aOp;          /* Copy of p->aOp */
+  Op *pOp = aOp;             /* Current operation */
+#if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)
+  Op *pOrigOp;               /* Value of pOp at the top of the loop */
+#endif
+#ifdef SQLITE_DEBUG
+  int nExtraDelete = 0;      /* Verifies FORDELETE and AUXDELETE flags */
+#endif
+  int rc = SQLITE_OK;        /* Value to return */
+  sqlite3 *db = p->db;       /* The database */
+  u8 resetSchemaOnFault = 0; /* Reset schema after an error if positive */
+  u8 encoding = ENC(db);     /* The database encoding */
+  int iCompare = 0;          /* Result of last comparison */
+  unsigned nVmStep = 0;      /* Number of virtual machine steps */
+#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
+  unsigned nProgressLimit = 0;/* Invoke xProgress() when nVmStep reaches this */
+#endif
+  Mem *aMem = p->aMem;       /* Copy of p->aMem */
+  Mem *pIn1 = 0;             /* 1st input operand */
+  Mem *pIn2 = 0;             /* 2nd input operand */
+  Mem *pIn3 = 0;             /* 3rd input operand */
+  Mem *pOut = 0;             /* Output operand */
+  int *aPermute = 0;         /* Permutation of columns for OP_Compare */
+  i64 lastRowid = db->lastRowid;  /* Saved value of the last insert ROWID */
+#ifdef VDBE_PROFILE
+  u64 start;                 /* CPU clock count at start of opcode */
+#endif
+  /*** INSERT STACK UNION HERE ***/
+
+  assert( p->magic==VDBE_MAGIC_RUN );  /* sqlite3_step() verifies this */
+  sqlite3VdbeEnter(p);
+  if( p->rc==SQLITE_NOMEM ){
+    /* This happens if a malloc() inside a call to sqlite3_column_text() or
+    ** sqlite3_column_text16() failed.  */
+    goto no_mem;
+  }
+  assert( p->rc==SQLITE_OK || (p->rc&0xff)==SQLITE_BUSY );
+  assert( p->bIsReader || p->readOnly!=0 );
+  p->rc = SQLITE_OK;
+  p->iCurrentTime = 0;
+  assert( p->explain==0 );
+  p->pResultSet = 0;
+  db->busyHandler.nBusy = 0;
+  if( db->u1.isInterrupted ) goto abort_due_to_interrupt;
+  sqlite3VdbeIOTraceSql(p);
+#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
+  if( db->xProgress ){
+    u32 iPrior = p->aCounter[SQLITE_STMTSTATUS_VM_STEP];
+    assert( 0 < db->nProgressOps );
+    nProgressLimit = db->nProgressOps - (iPrior % db->nProgressOps);
+  }
+#endif
+#ifdef SQLITE_DEBUG
+  sqlite3BeginBenignMalloc();
+  if( p->pc==0
+   && (p->db->flags & (SQLITE_VdbeListing|SQLITE_VdbeEQP|SQLITE_VdbeTrace))!=0
+  ){
+    int i;
+    int once = 1;
+    sqlite3VdbePrintSql(p);
+    if( p->db->flags & SQLITE_VdbeListing ){
+      printf("VDBE Program Listing:\n");
+      for(i=0; i<p->nOp; i++){
+        sqlite3VdbePrintOp(stdout, i, &aOp[i]);
+      }
+    }
+    if( p->db->flags & SQLITE_VdbeEQP ){
+      for(i=0; i<p->nOp; i++){
+        if( aOp[i].opcode==OP_Explain ){
+          if( once ) printf("VDBE Query Plan:\n");
+          printf("%s\n", aOp[i].p4.z);
+          once = 0;
+        }
+      }
+    }
+    if( p->db->flags & SQLITE_VdbeTrace )  printf("VDBE Trace:\n");
+  }
+  sqlite3EndBenignMalloc();
+#endif
+  for(pOp=&aOp[p->pc]; 1; pOp++){
+    /* Errors are detected by individual opcodes, with an immediate
+    ** jumps to abort_due_to_error. */
+    assert( rc==SQLITE_OK );
+
+    assert( pOp>=aOp && pOp<&aOp[p->nOp]);
+#ifdef VDBE_PROFILE
+    start = sqlite3Hwtime();
+#endif
+    nVmStep++;
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+    if( p->anExec ) p->anExec[(int)(pOp-aOp)]++;
+#endif
+
+    /* Only allow tracing if SQLITE_DEBUG is defined.
+    */
+#ifdef SQLITE_DEBUG
+    if( db->flags & SQLITE_VdbeTrace ){
+      sqlite3VdbePrintOp(stdout, (int)(pOp - aOp), pOp);
+    }
+#endif
+      
+
+    /* Check to see if we need to simulate an interrupt.  This only happens
+    ** if we have a special test build.
+    */
+#ifdef SQLITE_TEST
+    if( sqlite3_interrupt_count>0 ){
+      sqlite3_interrupt_count--;
+      if( sqlite3_interrupt_count==0 ){
+        sqlite3_interrupt(db);
+      }
+    }
+#endif
+
+    /* Sanity checking on other operands */
+#ifdef SQLITE_DEBUG
+    {
+      u8 opProperty = sqlite3OpcodeProperty[pOp->opcode];
+      if( (opProperty & OPFLG_IN1)!=0 ){
+        assert( pOp->p1>0 );
+        assert( pOp->p1<=(p->nMem+1 - p->nCursor) );
+        assert( memIsValid(&aMem[pOp->p1]) );
+        assert( sqlite3VdbeCheckMemInvariants(&aMem[pOp->p1]) );
+        REGISTER_TRACE(pOp->p1, &aMem[pOp->p1]);
+      }
+      if( (opProperty & OPFLG_IN2)!=0 ){
+        assert( pOp->p2>0 );
+        assert( pOp->p2<=(p->nMem+1 - p->nCursor) );
+        assert( memIsValid(&aMem[pOp->p2]) );
+        assert( sqlite3VdbeCheckMemInvariants(&aMem[pOp->p2]) );
+        REGISTER_TRACE(pOp->p2, &aMem[pOp->p2]);
+      }
+      if( (opProperty & OPFLG_IN3)!=0 ){
+        assert( pOp->p3>0 );
+        assert( pOp->p3<=(p->nMem+1 - p->nCursor) );
+        assert( memIsValid(&aMem[pOp->p3]) );
+        assert( sqlite3VdbeCheckMemInvariants(&aMem[pOp->p3]) );
+        REGISTER_TRACE(pOp->p3, &aMem[pOp->p3]);
+      }
+      if( (opProperty & OPFLG_OUT2)!=0 ){
+        assert( pOp->p2>0 );
+        assert( pOp->p2<=(p->nMem+1 - p->nCursor) );
+        memAboutToChange(p, &aMem[pOp->p2]);
+      }
+      if( (opProperty & OPFLG_OUT3)!=0 ){
+        assert( pOp->p3>0 );
+        assert( pOp->p3<=(p->nMem+1 - p->nCursor) );
+        memAboutToChange(p, &aMem[pOp->p3]);
+      }
+    }
+#endif
+#if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)
+    pOrigOp = pOp;
+#endif
+  
+    switch( pOp->opcode ){
+
+/*****************************************************************************
+** What follows is a massive switch statement where each case implements a
+** separate instruction in the virtual machine.  If we follow the usual
+** indentation conventions, each case should be indented by 6 spaces.  But
+** that is a lot of wasted space on the left margin.  So the code within
+** the switch statement will break with convention and be flush-left. Another
+** big comment (similar to this one) will mark the point in the code where
+** we transition back to normal indentation.
+**
+** The formatting of each case is important.  The makefile for SQLite
+** generates two C files "opcodes.h" and "opcodes.c" by scanning this
+** file looking for lines that begin with "case OP_".  The opcodes.h files
+** will be filled with #defines that give unique integer values to each
+** opcode and the opcodes.c file is filled with an array of strings where
+** each string is the symbolic name for the corresponding opcode.  If the
+** case statement is followed by a comment of the form "/# same as ... #/"
+** that comment is used to determine the particular value of the opcode.
+**
+** Other keywords in the comment that follows each case are used to
+** construct the OPFLG_INITIALIZER value that initializes opcodeProperty[].
+** Keywords include: in1, in2, in3, out2, out3.  See
+** the mkopcodeh.awk script for additional information.
+**
+** Documentation about VDBE opcodes is generated by scanning this file
+** for lines of that contain "Opcode:".  That line and all subsequent
+** comment lines are used in the generation of the opcode.html documentation
+** file.
+**
+** SUMMARY:
+**
+**     Formatting is important to scripts that scan this file.
+**     Do not deviate from the formatting style currently in use.
+**
+*****************************************************************************/
+
+/* Opcode:  Goto * P2 * * *
+**
+** An unconditional jump to address P2.
+** The next instruction executed will be 
+** the one at index P2 from the beginning of
+** the program.
+**
+** The P1 parameter is not actually used by this opcode.  However, it
+** is sometimes set to 1 instead of 0 as a hint to the command-line shell
+** that this Goto is the bottom of a loop and that the lines from P2 down
+** to the current line should be indented for EXPLAIN output.
+*/
+case OP_Goto: {             /* jump */
+jump_to_p2_and_check_for_interrupt:
+  pOp = &aOp[pOp->p2 - 1];
+
+  /* Opcodes that are used as the bottom of a loop (OP_Next, OP_Prev,
+  ** OP_VNext, OP_RowSetNext, or OP_SorterNext) all jump here upon
+  ** completion.  Check to see if sqlite3_interrupt() has been called
+  ** or if the progress callback needs to be invoked. 
+  **
+  ** This code uses unstructured "goto" statements and does not look clean.
+  ** But that is not due to sloppy coding habits. The code is written this
+  ** way for performance, to avoid having to run the interrupt and progress
+  ** checks on every opcode.  This helps sqlite3_step() to run about 1.5%
+  ** faster according to "valgrind --tool=cachegrind" */
+check_for_interrupt:
+  if( db->u1.isInterrupted ) goto abort_due_to_interrupt;
+#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
+  /* Call the progress callback if it is configured and the required number
+  ** of VDBE ops have been executed (either since this invocation of
+  ** sqlite3VdbeExec() or since last time the progress callback was called).
+  ** If the progress callback returns non-zero, exit the virtual machine with
+  ** a return code SQLITE_ABORT.
+  */
+  if( db->xProgress!=0 && nVmStep>=nProgressLimit ){
+    assert( db->nProgressOps!=0 );
+    nProgressLimit = nVmStep + db->nProgressOps - (nVmStep%db->nProgressOps);
+    if( db->xProgress(db->pProgressArg) ){
+      rc = SQLITE_INTERRUPT;
+      goto abort_due_to_error;
+    }
+  }
+#endif
+  
+  break;
+}
+
+/* Opcode:  Gosub P1 P2 * * *
+**
+** Write the current address onto register P1
+** and then jump to address P2.
+*/
+case OP_Gosub: {            /* jump */
+  assert( pOp->p1>0 && pOp->p1<=(p->nMem+1 - p->nCursor) );
+  pIn1 = &aMem[pOp->p1];
+  assert( VdbeMemDynamic(pIn1)==0 );
+  memAboutToChange(p, pIn1);
+  pIn1->flags = MEM_Int;
+  pIn1->u.i = (int)(pOp-aOp);
+  REGISTER_TRACE(pOp->p1, pIn1);
+
+  /* Most jump operations do a goto to this spot in order to update
+  ** the pOp pointer. */
+jump_to_p2:
+  pOp = &aOp[pOp->p2 - 1];
+  break;
+}
+
+/* Opcode:  Return P1 * * * *
+**
+** Jump to the next instruction after the address in register P1.  After
+** the jump, register P1 becomes undefined.
+*/
+case OP_Return: {           /* in1 */
+  pIn1 = &aMem[pOp->p1];
+  assert( pIn1->flags==MEM_Int );
+  pOp = &aOp[pIn1->u.i];
+  pIn1->flags = MEM_Undefined;
+  break;
+}
+
+/* Opcode: InitCoroutine P1 P2 P3 * *
+**
+** Set up register P1 so that it will Yield to the coroutine
+** located at address P3.
+**
+** If P2!=0 then the coroutine implementation immediately follows
+** this opcode.  So jump over the coroutine implementation to
+** address P2.
+**
+** See also: EndCoroutine
+*/
+case OP_InitCoroutine: {     /* jump */
+  assert( pOp->p1>0 &&  pOp->p1<=(p->nMem+1 - p->nCursor) );
+  assert( pOp->p2>=0 && pOp->p2<p->nOp );
+  assert( pOp->p3>=0 && pOp->p3<p->nOp );
+  pOut = &aMem[pOp->p1];
+  assert( !VdbeMemDynamic(pOut) );
+  pOut->u.i = pOp->p3 - 1;
+  pOut->flags = MEM_Int;
+  if( pOp->p2 ) goto jump_to_p2;
+  break;
+}
+
+/* Opcode:  EndCoroutine P1 * * * *
+**
+** The instruction at the address in register P1 is a Yield.
+** Jump to the P2 parameter of that Yield.
+** After the jump, register P1 becomes undefined.
+**
+** See also: InitCoroutine
+*/
+case OP_EndCoroutine: {           /* in1 */
+  VdbeOp *pCaller;
+  pIn1 = &aMem[pOp->p1];
+  assert( pIn1->flags==MEM_Int );
+  assert( pIn1->u.i>=0 && pIn1->u.i<p->nOp );
+  pCaller = &aOp[pIn1->u.i];
+  assert( pCaller->opcode==OP_Yield );
+  assert( pCaller->p2>=0 && pCaller->p2<p->nOp );
+  pOp = &aOp[pCaller->p2 - 1];
+  pIn1->flags = MEM_Undefined;
+  break;
+}
+
+/* Opcode:  Yield P1 P2 * * *
+**
+** Swap the program counter with the value in register P1.  This
+** has the effect of yielding to a coroutine.
+**
+** If the coroutine that is launched by this instruction ends with
+** Yield or Return then continue to the next instruction.  But if
+** the coroutine launched by this instruction ends with
+** EndCoroutine, then jump to P2 rather than continuing with the
+** next instruction.
+**
+** See also: InitCoroutine
+*/
+case OP_Yield: {            /* in1, jump */
+  int pcDest;
+  pIn1 = &aMem[pOp->p1];
+  assert( VdbeMemDynamic(pIn1)==0 );
+  pIn1->flags = MEM_Int;
+  pcDest = (int)pIn1->u.i;
+  pIn1->u.i = (int)(pOp - aOp);
+  REGISTER_TRACE(pOp->p1, pIn1);
+  pOp = &aOp[pcDest];
+  break;
+}
+
+/* Opcode:  HaltIfNull  P1 P2 P3 P4 P5
+** Synopsis: if r[P3]=null halt
+**
+** Check the value in register P3.  If it is NULL then Halt using
+** parameter P1, P2, and P4 as if this were a Halt instruction.  If the
+** value in register P3 is not NULL, then this routine is a no-op.
+** The P5 parameter should be 1.
+*/
+case OP_HaltIfNull: {      /* in3 */
+  pIn3 = &aMem[pOp->p3];
+  if( (pIn3->flags & MEM_Null)==0 ) break;
+  /* Fall through into OP_Halt */
+}
+
+/* Opcode:  Halt P1 P2 * P4 P5
+**
+** Exit immediately.  All open cursors, etc are closed
+** automatically.
+**
+** P1 is the result code returned by sqlite3_exec(), sqlite3_reset(),
+** or sqlite3_finalize().  For a normal halt, this should be SQLITE_OK (0).
+** For errors, it can be some other value.  If P1!=0 then P2 will determine
+** whether or not to rollback the current transaction.  Do not rollback
+** if P2==OE_Fail. Do the rollback if P2==OE_Rollback.  If P2==OE_Abort,
+** then back out all changes that have occurred during this execution of the
+** VDBE, but do not rollback the transaction. 
+**
+** If P4 is not null then it is an error message string.
+**
+** P5 is a value between 0 and 4, inclusive, that modifies the P4 string.
+**
+**    0:  (no change)
+**    1:  NOT NULL contraint failed: P4
+**    2:  UNIQUE constraint failed: P4
+**    3:  CHECK constraint failed: P4
+**    4:  FOREIGN KEY constraint failed: P4
+**
+** If P5 is not zero and P4 is NULL, then everything after the ":" is
+** omitted.
+**
+** There is an implied "Halt 0 0 0" instruction inserted at the very end of
+** every program.  So a jump past the last instruction of the program
+** is the same as executing Halt.
+*/
+case OP_Halt: {
+  VdbeFrame *pFrame;
+  int pcx;
+
+  pcx = (int)(pOp - aOp);
+  if( pOp->p1==SQLITE_OK && p->pFrame ){
+    /* Halt the sub-program. Return control to the parent frame. */
+    pFrame = p->pFrame;
+    p->pFrame = pFrame->pParent;
+    p->nFrame--;
+    sqlite3VdbeSetChanges(db, p->nChange);
+    pcx = sqlite3VdbeFrameRestore(pFrame);
+    lastRowid = db->lastRowid;
+    if( pOp->p2==OE_Ignore ){
+      /* Instruction pcx is the OP_Program that invoked the sub-program 
+      ** currently being halted. If the p2 instruction of this OP_Halt
+      ** instruction is set to OE_Ignore, then the sub-program is throwing
+      ** an IGNORE exception. In this case jump to the address specified
+      ** as the p2 of the calling OP_Program.  */
+      pcx = p->aOp[pcx].p2-1;
+    }
+    aOp = p->aOp;
+    aMem = p->aMem;
+    pOp = &aOp[pcx];
+    break;
+  }
+  p->rc = pOp->p1;
+  p->errorAction = (u8)pOp->p2;
+  p->pc = pcx;
+  assert( pOp->p5>=0 && pOp->p5<=4 );
+  if( p->rc ){
+    if( pOp->p5 ){
+      static const char * const azType[] = { "NOT NULL", "UNIQUE", "CHECK",
+                                             "FOREIGN KEY" };
+      testcase( pOp->p5==1 );
+      testcase( pOp->p5==2 );
+      testcase( pOp->p5==3 );
+      testcase( pOp->p5==4 );
+      sqlite3VdbeError(p, "%s constraint failed", azType[pOp->p5-1]);
+      if( pOp->p4.z ){
+        p->zErrMsg = sqlite3MPrintf(db, "%z: %s", p->zErrMsg, pOp->p4.z);
+      }
+    }else{
+      sqlite3VdbeError(p, "%s", pOp->p4.z);
+    }
+    sqlite3_log(pOp->p1, "abort at %d in [%s]: %s", pcx, p->zSql, p->zErrMsg);
+  }
+  rc = sqlite3VdbeHalt(p);
+  assert( rc==SQLITE_BUSY || rc==SQLITE_OK || rc==SQLITE_ERROR );
+  if( rc==SQLITE_BUSY ){
+    p->rc = SQLITE_BUSY;
+  }else{
+    assert( rc==SQLITE_OK || (p->rc&0xff)==SQLITE_CONSTRAINT );
+    assert( rc==SQLITE_OK || db->nDeferredCons>0 || db->nDeferredImmCons>0 );
+    rc = p->rc ? SQLITE_ERROR : SQLITE_DONE;
+  }
+  goto vdbe_return;
+}
+
+/* Opcode: Integer P1 P2 * * *
+** Synopsis: r[P2]=P1
+**
+** The 32-bit integer value P1 is written into register P2.
+*/
+case OP_Integer: {         /* out2 */
+  pOut = out2Prerelease(p, pOp);
+  pOut->u.i = pOp->p1;
+  break;
+}
+
+/* Opcode: Int64 * P2 * P4 *
+** Synopsis: r[P2]=P4
+**
+** P4 is a pointer to a 64-bit integer value.
+** Write that value into register P2.
+*/
+case OP_Int64: {           /* out2 */
+  pOut = out2Prerelease(p, pOp);
+  assert( pOp->p4.pI64!=0 );
+  pOut->u.i = *pOp->p4.pI64;
+  break;
+}
+
+#ifndef SQLITE_OMIT_FLOATING_POINT
+/* Opcode: Real * P2 * P4 *
+** Synopsis: r[P2]=P4
+**
+** P4 is a pointer to a 64-bit floating point value.
+** Write that value into register P2.
+*/
+case OP_Real: {            /* same as TK_FLOAT, out2 */
+  pOut = out2Prerelease(p, pOp);
+  pOut->flags = MEM_Real;
+  assert( !sqlite3IsNaN(*pOp->p4.pReal) );
+  pOut->u.r = *pOp->p4.pReal;
+  break;
+}
+#endif
+
+/* Opcode: String8 * P2 * P4 *
+** Synopsis: r[P2]='P4'
+**
+** P4 points to a nul terminated UTF-8 string. This opcode is transformed 
+** into a String opcode before it is executed for the first time.  During
+** this transformation, the length of string P4 is computed and stored
+** as the P1 parameter.
+*/
+case OP_String8: {         /* same as TK_STRING, out2 */
+  assert( pOp->p4.z!=0 );
+  pOut = out2Prerelease(p, pOp);
+  pOp->opcode = OP_String;
+  pOp->p1 = sqlite3Strlen30(pOp->p4.z);
+
+#ifndef SQLITE_OMIT_UTF16
+  if( encoding!=SQLITE_UTF8 ){
+    rc = sqlite3VdbeMemSetStr(pOut, pOp->p4.z, -1, SQLITE_UTF8, SQLITE_STATIC);
+    assert( rc==SQLITE_OK || rc==SQLITE_TOOBIG );
+    if( SQLITE_OK!=sqlite3VdbeChangeEncoding(pOut, encoding) ) goto no_mem;
+    assert( pOut->szMalloc>0 && pOut->zMalloc==pOut->z );
+    assert( VdbeMemDynamic(pOut)==0 );
+    pOut->szMalloc = 0;
+    pOut->flags |= MEM_Static;
+    if( pOp->p4type==P4_DYNAMIC ){
+      sqlite3DbFree(db, pOp->p4.z);
+    }
+    pOp->p4type = P4_DYNAMIC;
+    pOp->p4.z = pOut->z;
+    pOp->p1 = pOut->n;
+  }
+  testcase( rc==SQLITE_TOOBIG );
+#endif
+  if( pOp->p1>db->aLimit[SQLITE_LIMIT_LENGTH] ){
+    goto too_big;
+  }
+  assert( rc==SQLITE_OK );
+  /* Fall through to the next case, OP_String */
+}
+  
+/* Opcode: String P1 P2 P3 P4 P5
+** Synopsis: r[P2]='P4' (len=P1)
+**
+** The string value P4 of length P1 (bytes) is stored in register P2.
+**
+** If P3 is not zero and the content of register P3 is equal to P5, then
+** the datatype of the register P2 is converted to BLOB.  The content is
+** the same sequence of bytes, it is merely interpreted as a BLOB instead
+** of a string, as if it had been CAST.  In other words:
+**
+** if( P3!=0 and reg[P3]==P5 ) reg[P2] := CAST(reg[P2] as BLOB)
+*/
+case OP_String: {          /* out2 */
+  assert( pOp->p4.z!=0 );
+  pOut = out2Prerelease(p, pOp);
+  pOut->flags = MEM_Str|MEM_Static|MEM_Term;
+  pOut->z = pOp->p4.z;
+  pOut->n = pOp->p1;
+  pOut->enc = encoding;
+  UPDATE_MAX_BLOBSIZE(pOut);
+#ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
+  if( pOp->p3>0 ){
+    assert( pOp->p3<=(p->nMem+1 - p->nCursor) );
+    pIn3 = &aMem[pOp->p3];
+    assert( pIn3->flags & MEM_Int );
+    if( pIn3->u.i==pOp->p5 ) pOut->flags = MEM_Blob|MEM_Static|MEM_Term;
+  }
+#endif
+  break;
+}
+
+/* Opcode: Null P1 P2 P3 * *
+** Synopsis: r[P2..P3]=NULL
+**
+** Write a NULL into registers P2.  If P3 greater than P2, then also write
+** NULL into register P3 and every register in between P2 and P3.  If P3
+** is less than P2 (typically P3 is zero) then only register P2 is
+** set to NULL.
+**
+** If the P1 value is non-zero, then also set the MEM_Cleared flag so that
+** NULL values will not compare equal even if SQLITE_NULLEQ is set on
+** OP_Ne or OP_Eq.
+*/
+case OP_Null: {           /* out2 */
+  int cnt;
+  u16 nullFlag;
+  pOut = out2Prerelease(p, pOp);
+  cnt = pOp->p3-pOp->p2;
+  assert( pOp->p3<=(p->nMem+1 - p->nCursor) );
+  pOut->flags = nullFlag = pOp->p1 ? (MEM_Null|MEM_Cleared) : MEM_Null;
+  pOut->n = 0;
+  while( cnt>0 ){
+    pOut++;
+    memAboutToChange(p, pOut);
+    sqlite3VdbeMemSetNull(pOut);
+    pOut->flags = nullFlag;
+    pOut->n = 0;
+    cnt--;
+  }
+  break;
+}
+
+/* Opcode: SoftNull P1 * * * *
+** Synopsis: r[P1]=NULL
+**
+** Set register P1 to have the value NULL as seen by the OP_MakeRecord
+** instruction, but do not free any string or blob memory associated with
+** the register, so that if the value was a string or blob that was
+** previously copied using OP_SCopy, the copies will continue to be valid.
+*/
+case OP_SoftNull: {
+  assert( pOp->p1>0 && pOp->p1<=(p->nMem+1 - p->nCursor) );
+  pOut = &aMem[pOp->p1];
+  pOut->flags = (pOut->flags|MEM_Null)&~MEM_Undefined;
+  break;
+}
+
+/* Opcode: Blob P1 P2 * P4 *
+** Synopsis: r[P2]=P4 (len=P1)
+**
+** P4 points to a blob of data P1 bytes long.  Store this
+** blob in register P2.
+*/
+case OP_Blob: {                /* out2 */
+  assert( pOp->p1 <= SQLITE_MAX_LENGTH );
+  pOut = out2Prerelease(p, pOp);
+  sqlite3VdbeMemSetStr(pOut, pOp->p4.z, pOp->p1, 0, 0);
+  pOut->enc = encoding;
+  UPDATE_MAX_BLOBSIZE(pOut);
+  break;
+}
+
+/* Opcode: Variable P1 P2 * P4 *
+** Synopsis: r[P2]=parameter(P1,P4)
+**
+** Transfer the values of bound parameter P1 into register P2
+**
+** If the parameter is named, then its name appears in P4.
+** The P4 value is used by sqlite3_bind_parameter_name().
+*/
+case OP_Variable: {            /* out2 */
+  Mem *pVar;       /* Value being transferred */
+
+  assert( pOp->p1>0 && pOp->p1<=p->nVar );
+  assert( pOp->p4.z==0 || pOp->p4.z==p->azVar[pOp->p1-1] );
+  pVar = &p->aVar[pOp->p1 - 1];
+  if( sqlite3VdbeMemTooBig(pVar) ){
+    goto too_big;
+  }
+  pOut = out2Prerelease(p, pOp);
+  sqlite3VdbeMemShallowCopy(pOut, pVar, MEM_Static);
+  UPDATE_MAX_BLOBSIZE(pOut);
+  break;
+}
+
+/* Opcode: Move P1 P2 P3 * *
+** Synopsis: r[P2@P3]=r[P1@P3]
+**
+** Move the P3 values in register P1..P1+P3-1 over into
+** registers P2..P2+P3-1.  Registers P1..P1+P3-1 are
+** left holding a NULL.  It is an error for register ranges
+** P1..P1+P3-1 and P2..P2+P3-1 to overlap.  It is an error
+** for P3 to be less than 1.
+*/
+case OP_Move: {
+  int n;           /* Number of registers left to copy */
+  int p1;          /* Register to copy from */
+  int p2;          /* Register to copy to */
+
+  n = pOp->p3;
+  p1 = pOp->p1;
+  p2 = pOp->p2;
+  assert( n>0 && p1>0 && p2>0 );
+  assert( p1+n<=p2 || p2+n<=p1 );
+
+  pIn1 = &aMem[p1];
+  pOut = &aMem[p2];
+  do{
+    assert( pOut<=&aMem[(p->nMem+1 - p->nCursor)] );
+    assert( pIn1<=&aMem[(p->nMem+1 - p->nCursor)] );
+    assert( memIsValid(pIn1) );
+    memAboutToChange(p, pOut);
+    sqlite3VdbeMemMove(pOut, pIn1);
+#ifdef SQLITE_DEBUG
+    if( pOut->pScopyFrom>=&aMem[p1] && pOut->pScopyFrom<pOut ){
+      pOut->pScopyFrom += pOp->p2 - p1;
+    }
+#endif
+    Deephemeralize(pOut);
+    REGISTER_TRACE(p2++, pOut);
+    pIn1++;
+    pOut++;
+  }while( --n );
+  break;
+}
+
+/* Opcode: Copy P1 P2 P3 * *
+** Synopsis: r[P2@P3+1]=r[P1@P3+1]
+**
+** Make a copy of registers P1..P1+P3 into registers P2..P2+P3.
+**
+** This instruction makes a deep copy of the value.  A duplicate
+** is made of any string or blob constant.  See also OP_SCopy.
+*/
+case OP_Copy: {
+  int n;
+
+  n = pOp->p3;
+  pIn1 = &aMem[pOp->p1];
+  pOut = &aMem[pOp->p2];
+  assert( pOut!=pIn1 );
+  while( 1 ){
+    sqlite3VdbeMemShallowCopy(pOut, pIn1, MEM_Ephem);
+    Deephemeralize(pOut);
+#ifdef SQLITE_DEBUG
+    pOut->pScopyFrom = 0;
+#endif
+    REGISTER_TRACE(pOp->p2+pOp->p3-n, pOut);
+    if( (n--)==0 ) break;
+    pOut++;
+    pIn1++;
+  }
+  break;
+}
+
+/* Opcode: SCopy P1 P2 * * *
+** Synopsis: r[P2]=r[P1]
+**
+** Make a shallow copy of register P1 into register P2.
+**
+** This instruction makes a shallow copy of the value.  If the value
+** is a string or blob, then the copy is only a pointer to the
+** original and hence if the original changes so will the copy.
+** Worse, if the original is deallocated, the copy becomes invalid.
+** Thus the program must guarantee that the original will not change
+** during the lifetime of the copy.  Use OP_Copy to make a complete
+** copy.
+*/
+case OP_SCopy: {            /* out2 */
+  pIn1 = &aMem[pOp->p1];
+  pOut = &aMem[pOp->p2];
+  assert( pOut!=pIn1 );
+  sqlite3VdbeMemShallowCopy(pOut, pIn1, MEM_Ephem);
+#ifdef SQLITE_DEBUG
+  if( pOut->pScopyFrom==0 ) pOut->pScopyFrom = pIn1;
+#endif
+  break;
+}
+
+/* Opcode: IntCopy P1 P2 * * *
+** Synopsis: r[P2]=r[P1]
+**
+** Transfer the integer value held in register P1 into register P2.
+**
+** This is an optimized version of SCopy that works only for integer
+** values.
+*/
+case OP_IntCopy: {            /* out2 */
+  pIn1 = &aMem[pOp->p1];
+  assert( (pIn1->flags & MEM_Int)!=0 );
+  pOut = &aMem[pOp->p2];
+  sqlite3VdbeMemSetInt64(pOut, pIn1->u.i);
+  break;
+}
+
+/* Opcode: ResultRow P1 P2 * * *
+** Synopsis: output=r[P1@P2]
+**
+** The registers P1 through P1+P2-1 contain a single row of
+** results. This opcode causes the sqlite3_step() call to terminate
+** with an SQLITE_ROW return code and it sets up the sqlite3_stmt
+** structure to provide access to the r(P1)..r(P1+P2-1) values as
+** the result row.
+*/
+case OP_ResultRow: {
+  Mem *pMem;
+  int i;
+  assert( p->nResColumn==pOp->p2 );
+  assert( pOp->p1>0 );
+  assert( pOp->p1+pOp->p2<=(p->nMem+1 - p->nCursor)+1 );
+
+#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
+  /* Run the progress counter just before returning.
+  */
+  if( db->xProgress!=0
+   && nVmStep>=nProgressLimit
+   && db->xProgress(db->pProgressArg)!=0
+  ){
+    rc = SQLITE_INTERRUPT;
+    goto abort_due_to_error;
+  }
+#endif
+
+  /* If this statement has violated immediate foreign key constraints, do
+  ** not return the number of rows modified. And do not RELEASE the statement
+  ** transaction. It needs to be rolled back.  */
+  if( SQLITE_OK!=(rc = sqlite3VdbeCheckFk(p, 0)) ){
+    assert( db->flags&SQLITE_CountRows );
+    assert( p->usesStmtJournal );
+    goto abort_due_to_error;
+  }
+
+  /* If the SQLITE_CountRows flag is set in sqlite3.flags mask, then 
+  ** DML statements invoke this opcode to return the number of rows 
+  ** modified to the user. This is the only way that a VM that
+  ** opens a statement transaction may invoke this opcode.
+  **
+  ** In case this is such a statement, close any statement transaction
+  ** opened by this VM before returning control to the user. This is to
+  ** ensure that statement-transactions are always nested, not overlapping.
+  ** If the open statement-transaction is not closed here, then the user
+  ** may step another VM that opens its own statement transaction. This
+  ** may lead to overlapping statement transactions.
+  **
+  ** The statement transaction is never a top-level transaction.  Hence
+  ** the RELEASE call below can never fail.
+  */
+  assert( p->iStatement==0 || db->flags&SQLITE_CountRows );
+  rc = sqlite3VdbeCloseStatement(p, SAVEPOINT_RELEASE);
+  assert( rc==SQLITE_OK );
+
+  /* Invalidate all ephemeral cursor row caches */
+  p->cacheCtr = (p->cacheCtr + 2)|1;
+
+  /* Make sure the results of the current row are \000 terminated
+  ** and have an assigned type.  The results are de-ephemeralized as
+  ** a side effect.
+  */
+  pMem = p->pResultSet = &aMem[pOp->p1];
+  for(i=0; i<pOp->p2; i++){
+    assert( memIsValid(&pMem[i]) );
+    Deephemeralize(&pMem[i]);
+    assert( (pMem[i].flags & MEM_Ephem)==0
+            || (pMem[i].flags & (MEM_Str|MEM_Blob))==0 );
+    sqlite3VdbeMemNulTerminate(&pMem[i]);
+    REGISTER_TRACE(pOp->p1+i, &pMem[i]);
+  }
+  if( db->mallocFailed ) goto no_mem;
+
+  if( db->mTrace & SQLITE_TRACE_ROW ){
+    db->xTrace(SQLITE_TRACE_ROW, db->pTraceArg, p, 0);
+  }
+
+  /* Return SQLITE_ROW
+  */
+  p->pc = (int)(pOp - aOp) + 1;
+  rc = SQLITE_ROW;
+  goto vdbe_return;
+}
+
+/* Opcode: Concat P1 P2 P3 * *
+** Synopsis: r[P3]=r[P2]+r[P1]
+**
+** Add the text in register P1 onto the end of the text in
+** register P2 and store the result in register P3.
+** If either the P1 or P2 text are NULL then store NULL in P3.
+**
+**   P3 = P2 || P1
+**
+** It is illegal for P1 and P3 to be the same register. Sometimes,
+** if P3 is the same register as P2, the implementation is able
+** to avoid a memcpy().
+*/
+case OP_Concat: {           /* same as TK_CONCAT, in1, in2, out3 */
+  i64 nByte;
+
+  pIn1 = &aMem[pOp->p1];
+  pIn2 = &aMem[pOp->p2];
+  pOut = &aMem[pOp->p3];
+  assert( pIn1!=pOut );
+  if( (pIn1->flags | pIn2->flags) & MEM_Null ){
+    sqlite3VdbeMemSetNull(pOut);
+    break;
+  }
+  if( ExpandBlob(pIn1) || ExpandBlob(pIn2) ) goto no_mem;
+  Stringify(pIn1, encoding);
+  Stringify(pIn2, encoding);
+  nByte = pIn1->n + pIn2->n;
+  if( nByte>db->aLimit[SQLITE_LIMIT_LENGTH] ){
+    goto too_big;
+  }
+  if( sqlite3VdbeMemGrow(pOut, (int)nByte+2, pOut==pIn2) ){
+    goto no_mem;
+  }
+  MemSetTypeFlag(pOut, MEM_Str);
+  if( pOut!=pIn2 ){
+    memcpy(pOut->z, pIn2->z, pIn2->n);
+  }
+  memcpy(&pOut->z[pIn2->n], pIn1->z, pIn1->n);
+  pOut->z[nByte]=0;
+  pOut->z[nByte+1] = 0;
+  pOut->flags |= MEM_Term;
+  pOut->n = (int)nByte;
+  pOut->enc = encoding;
+  UPDATE_MAX_BLOBSIZE(pOut);
+  break;
+}
+
+/* Opcode: Add P1 P2 P3 * *
+** Synopsis: r[P3]=r[P1]+r[P2]
+**
+** Add the value in register P1 to the value in register P2
+** and store the result in register P3.
+** If either input is NULL, the result is NULL.
+*/
+/* Opcode: Multiply P1 P2 P3 * *
+** Synopsis: r[P3]=r[P1]*r[P2]
+**
+**
+** Multiply the value in register P1 by the value in register P2
+** and store the result in register P3.
+** If either input is NULL, the result is NULL.
+*/
+/* Opcode: Subtract P1 P2 P3 * *
+** Synopsis: r[P3]=r[P2]-r[P1]
+**
+** Subtract the value in register P1 from the value in register P2
+** and store the result in register P3.
+** If either input is NULL, the result is NULL.
+*/
+/* Opcode: Divide P1 P2 P3 * *
+** Synopsis: r[P3]=r[P2]/r[P1]
+**
+** Divide the value in register P1 by the value in register P2
+** and store the result in register P3 (P3=P2/P1). If the value in 
+** register P1 is zero, then the result is NULL. If either input is 
+** NULL, the result is NULL.
+*/
+/* Opcode: Remainder P1 P2 P3 * *
+** Synopsis: r[P3]=r[P2]%r[P1]
+**
+** Compute the remainder after integer register P2 is divided by 
+** register P1 and store the result in register P3. 
+** If the value in register P1 is zero the result is NULL.
+** If either operand is NULL, the result is NULL.
+*/
+case OP_Add:                   /* same as TK_PLUS, in1, in2, out3 */
+case OP_Subtract:              /* same as TK_MINUS, in1, in2, out3 */
+case OP_Multiply:              /* same as TK_STAR, in1, in2, out3 */
+case OP_Divide:                /* same as TK_SLASH, in1, in2, out3 */
+case OP_Remainder: {           /* same as TK_REM, in1, in2, out3 */
+  char bIntint;   /* Started out as two integer operands */
+  u16 flags;      /* Combined MEM_* flags from both inputs */
+  u16 type1;      /* Numeric type of left operand */
+  u16 type2;      /* Numeric type of right operand */
+  i64 iA;         /* Integer value of left operand */
+  i64 iB;         /* Integer value of right operand */
+  double rA;      /* Real value of left operand */
+  double rB;      /* Real value of right operand */
+
+  pIn1 = &aMem[pOp->p1];
+  type1 = numericType(pIn1);
+  pIn2 = &aMem[pOp->p2];
+  type2 = numericType(pIn2);
+  pOut = &aMem[pOp->p3];
+  flags = pIn1->flags | pIn2->flags;
+  if( (flags & MEM_Null)!=0 ) goto arithmetic_result_is_null;
+  if( (type1 & type2 & MEM_Int)!=0 ){
+    iA = pIn1->u.i;
+    iB = pIn2->u.i;
+    bIntint = 1;
+    switch( pOp->opcode ){
+      case OP_Add:       if( sqlite3AddInt64(&iB,iA) ) goto fp_math;  break;
+      case OP_Subtract:  if( sqlite3SubInt64(&iB,iA) ) goto fp_math;  break;
+      case OP_Multiply:  if( sqlite3MulInt64(&iB,iA) ) goto fp_math;  break;
+      case OP_Divide: {
+        if( iA==0 ) goto arithmetic_result_is_null;
+        if( iA==-1 && iB==SMALLEST_INT64 ) goto fp_math;
+        iB /= iA;
+        break;
+      }
+      default: {
+        if( iA==0 ) goto arithmetic_result_is_null;
+        if( iA==-1 ) iA = 1;
+        iB %= iA;
+        break;
+      }
+    }
+    pOut->u.i = iB;
+    MemSetTypeFlag(pOut, MEM_Int);
+  }else{
+    bIntint = 0;
+fp_math:
+    rA = sqlite3VdbeRealValue(pIn1);
+    rB = sqlite3VdbeRealValue(pIn2);
+    switch( pOp->opcode ){
+      case OP_Add:         rB += rA;       break;
+      case OP_Subtract:    rB -= rA;       break;
+      case OP_Multiply:    rB *= rA;       break;
+      case OP_Divide: {
+        /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
+        if( rA==(double)0 ) goto arithmetic_result_is_null;
+        rB /= rA;
+        break;
+      }
+      default: {
+        iA = (i64)rA;
+        iB = (i64)rB;
+        if( iA==0 ) goto arithmetic_result_is_null;
+        if( iA==-1 ) iA = 1;
+        rB = (double)(iB % iA);
+        break;
+      }
+    }
+#ifdef SQLITE_OMIT_FLOATING_POINT
+    pOut->u.i = rB;
+    MemSetTypeFlag(pOut, MEM_Int);
+#else
+    if( sqlite3IsNaN(rB) ){
+      goto arithmetic_result_is_null;
+    }
+    pOut->u.r = rB;
+    MemSetTypeFlag(pOut, MEM_Real);
+    if( ((type1|type2)&MEM_Real)==0 && !bIntint ){
+      sqlite3VdbeIntegerAffinity(pOut);
+    }
+#endif
+  }
+  break;
+
+arithmetic_result_is_null:
+  sqlite3VdbeMemSetNull(pOut);
+  break;
+}
+
+/* Opcode: CollSeq P1 * * P4
+**
+** P4 is a pointer to a CollSeq struct. If the next call to a user function
+** or aggregate calls sqlite3GetFuncCollSeq(), this collation sequence will
+** be returned. This is used by the built-in min(), max() and nullif()
+** functions.
+**
+** If P1 is not zero, then it is a register that a subsequent min() or
+** max() aggregate will set to 1 if the current row is not the minimum or
+** maximum.  The P1 register is initialized to 0 by this instruction.
+**
+** The interface used by the implementation of the aforementioned functions
+** to retrieve the collation sequence set by this opcode is not available
+** publicly.  Only built-in functions have access to this feature.
+*/
+case OP_CollSeq: {
+  assert( pOp->p4type==P4_COLLSEQ );
+  if( pOp->p1 ){
+    sqlite3VdbeMemSetInt64(&aMem[pOp->p1], 0);
+  }
+  break;
+}
+
+/* Opcode: Function0 P1 P2 P3 P4 P5
+** Synopsis: r[P3]=func(r[P2@P5])
+**
+** Invoke a user function (P4 is a pointer to a FuncDef object that
+** defines the function) with P5 arguments taken from register P2 and
+** successors.  The result of the function is stored in register P3.
+** Register P3 must not be one of the function inputs.
+**
+** P1 is a 32-bit bitmask indicating whether or not each argument to the 
+** function was determined to be constant at compile time. If the first
+** argument was constant then bit 0 of P1 is set. This is used to determine
+** whether meta data associated with a user function argument using the
+** sqlite3_set_auxdata() API may be safely retained until the next
+** invocation of this opcode.
+**
+** See also: Function, AggStep, AggFinal
+*/
+/* Opcode: Function P1 P2 P3 P4 P5
+** Synopsis: r[P3]=func(r[P2@P5])
+**
+** Invoke a user function (P4 is a pointer to an sqlite3_context object that
+** contains a pointer to the function to be run) with P5 arguments taken
+** from register P2 and successors.  The result of the function is stored
+** in register P3.  Register P3 must not be one of the function inputs.
+**
+** P1 is a 32-bit bitmask indicating whether or not each argument to the 
+** function was determined to be constant at compile time. If the first
+** argument was constant then bit 0 of P1 is set. This is used to determine
+** whether meta data associated with a user function argument using the
+** sqlite3_set_auxdata() API may be safely retained until the next
+** invocation of this opcode.
+**
+** SQL functions are initially coded as OP_Function0 with P4 pointing
+** to a FuncDef object.  But on first evaluation, the P4 operand is
+** automatically converted into an sqlite3_context object and the operation
+** changed to this OP_Function opcode.  In this way, the initialization of
+** the sqlite3_context object occurs only once, rather than once for each
+** evaluation of the function.
+**
+** See also: Function0, AggStep, AggFinal
+*/
+case OP_Function0: {
+  int n;
+  sqlite3_context *pCtx;
+
+  assert( pOp->p4type==P4_FUNCDEF );
+  n = pOp->p5;
+  assert( pOp->p3>0 && pOp->p3<=(p->nMem+1 - p->nCursor) );
+  assert( n==0 || (pOp->p2>0 && pOp->p2+n<=(p->nMem+1 - p->nCursor)+1) );
+  assert( pOp->p3<pOp->p2 || pOp->p3>=pOp->p2+n );
+  pCtx = sqlite3DbMallocRawNN(db, sizeof(*pCtx) + (n-1)*sizeof(sqlite3_value*));
+  if( pCtx==0 ) goto no_mem;
+  pCtx->pOut = 0;
+  pCtx->pFunc = pOp->p4.pFunc;
+  pCtx->iOp = (int)(pOp - aOp);
+  pCtx->pVdbe = p;
+  pCtx->argc = n;
+  pOp->p4type = P4_FUNCCTX;
+  pOp->p4.pCtx = pCtx;
+  pOp->opcode = OP_Function;
+  /* Fall through into OP_Function */
+}
+case OP_Function: {
+  int i;
+  sqlite3_context *pCtx;
+
+  assert( pOp->p4type==P4_FUNCCTX );
+  pCtx = pOp->p4.pCtx;
+
+  /* If this function is inside of a trigger, the register array in aMem[]
+  ** might change from one evaluation to the next.  The next block of code
+  ** checks to see if the register array has changed, and if so it
+  ** reinitializes the relavant parts of the sqlite3_context object */
+  pOut = &aMem[pOp->p3];
+  if( pCtx->pOut != pOut ){
+    pCtx->pOut = pOut;
+    for(i=pCtx->argc-1; i>=0; i--) pCtx->argv[i] = &aMem[pOp->p2+i];
+  }
+
+  memAboutToChange(p, pCtx->pOut);
+#ifdef SQLITE_DEBUG
+  for(i=0; i<pCtx->argc; i++){
+    assert( memIsValid(pCtx->argv[i]) );
+    REGISTER_TRACE(pOp->p2+i, pCtx->argv[i]);
+  }
+#endif
+  MemSetTypeFlag(pCtx->pOut, MEM_Null);
+  pCtx->fErrorOrAux = 0;
+  db->lastRowid = lastRowid;
+  (*pCtx->pFunc->xSFunc)(pCtx, pCtx->argc, pCtx->argv);/* IMP: R-24505-23230 */
+  lastRowid = db->lastRowid;  /* Remember rowid changes made by xSFunc */
+
+  /* If the function returned an error, throw an exception */
+  if( pCtx->fErrorOrAux ){
+    if( pCtx->isError ){
+      sqlite3VdbeError(p, "%s", sqlite3_value_text(pCtx->pOut));
+      rc = pCtx->isError;
+    }
+    sqlite3VdbeDeleteAuxData(db, &p->pAuxData, pCtx->iOp, pOp->p1);
+    if( rc ) goto abort_due_to_error;
+  }
+
+  /* Copy the result of the function into register P3 */
+  if( pOut->flags & (MEM_Str|MEM_Blob) ){
+    sqlite3VdbeChangeEncoding(pCtx->pOut, encoding);
+    if( sqlite3VdbeMemTooBig(pCtx->pOut) ) goto too_big;
+  }
+
+  REGISTER_TRACE(pOp->p3, pCtx->pOut);
+  UPDATE_MAX_BLOBSIZE(pCtx->pOut);
+  break;
+}
+
+/* Opcode: BitAnd P1 P2 P3 * *
+** Synopsis: r[P3]=r[P1]&r[P2]
+**
+** Take the bit-wise AND of the values in register P1 and P2 and
+** store the result in register P3.
+** If either input is NULL, the result is NULL.
+*/
+/* Opcode: BitOr P1 P2 P3 * *
+** Synopsis: r[P3]=r[P1]|r[P2]
+**
+** Take the bit-wise OR of the values in register P1 and P2 and
+** store the result in register P3.
+** If either input is NULL, the result is NULL.
+*/
+/* Opcode: ShiftLeft P1 P2 P3 * *
+** Synopsis: r[P3]=r[P2]<<r[P1]
+**
+** Shift the integer value in register P2 to the left by the
+** number of bits specified by the integer in register P1.
+** Store the result in register P3.
+** If either input is NULL, the result is NULL.
+*/
+/* Opcode: ShiftRight P1 P2 P3 * *
+** Synopsis: r[P3]=r[P2]>>r[P1]
+**
+** Shift the integer value in register P2 to the right by the
+** number of bits specified by the integer in register P1.
+** Store the result in register P3.
+** If either input is NULL, the result is NULL.
+*/
+case OP_BitAnd:                 /* same as TK_BITAND, in1, in2, out3 */
+case OP_BitOr:                  /* same as TK_BITOR, in1, in2, out3 */
+case OP_ShiftLeft:              /* same as TK_LSHIFT, in1, in2, out3 */
+case OP_ShiftRight: {           /* same as TK_RSHIFT, in1, in2, out3 */
+  i64 iA;
+  u64 uA;
+  i64 iB;
+  u8 op;
+
+  pIn1 = &aMem[pOp->p1];
+  pIn2 = &aMem[pOp->p2];
+  pOut = &aMem[pOp->p3];
+  if( (pIn1->flags | pIn2->flags) & MEM_Null ){
+    sqlite3VdbeMemSetNull(pOut);
+    break;
+  }
+  iA = sqlite3VdbeIntValue(pIn2);
+  iB = sqlite3VdbeIntValue(pIn1);
+  op = pOp->opcode;
+  if( op==OP_BitAnd ){
+    iA &= iB;
+  }else if( op==OP_BitOr ){
+    iA |= iB;
+  }else if( iB!=0 ){
+    assert( op==OP_ShiftRight || op==OP_ShiftLeft );
+
+    /* If shifting by a negative amount, shift in the other direction */
+    if( iB<0 ){
+      assert( OP_ShiftRight==OP_ShiftLeft+1 );
+      op = 2*OP_ShiftLeft + 1 - op;
+      iB = iB>(-64) ? -iB : 64;
+    }
+
+    if( iB>=64 ){
+      iA = (iA>=0 || op==OP_ShiftLeft) ? 0 : -1;
+    }else{
+      memcpy(&uA, &iA, sizeof(uA));
+      if( op==OP_ShiftLeft ){
+        uA <<= iB;
+      }else{
+        uA >>= iB;
+        /* Sign-extend on a right shift of a negative number */
+        if( iA<0 ) uA |= ((((u64)0xffffffff)<<32)|0xffffffff) << (64-iB);
+      }
+      memcpy(&iA, &uA, sizeof(iA));
+    }
+  }
+  pOut->u.i = iA;
+  MemSetTypeFlag(pOut, MEM_Int);
+  break;
+}
+
+/* Opcode: AddImm  P1 P2 * * *
+** Synopsis: r[P1]=r[P1]+P2
+** 
+** Add the constant P2 to the value in register P1.
+** The result is always an integer.
+**
+** To force any register to be an integer, just add 0.
+*/
+case OP_AddImm: {            /* in1 */
+  pIn1 = &aMem[pOp->p1];
+  memAboutToChange(p, pIn1);
+  sqlite3VdbeMemIntegerify(pIn1);
+  pIn1->u.i += pOp->p2;
+  break;
+}
+
+/* Opcode: MustBeInt P1 P2 * * *
+** 
+** Force the value in register P1 to be an integer.  If the value
+** in P1 is not an integer and cannot be converted into an integer
+** without data loss, then jump immediately to P2, or if P2==0
+** raise an SQLITE_MISMATCH exception.
+*/
+case OP_MustBeInt: {            /* jump, in1 */
+  pIn1 = &aMem[pOp->p1];
+  if( (pIn1->flags & MEM_Int)==0 ){
+    applyAffinity(pIn1, SQLITE_AFF_NUMERIC, encoding);
+    VdbeBranchTaken((pIn1->flags&MEM_Int)==0, 2);
+    if( (pIn1->flags & MEM_Int)==0 ){
+      if( pOp->p2==0 ){
+        rc = SQLITE_MISMATCH;
+        goto abort_due_to_error;
+      }else{
+        goto jump_to_p2;
+      }
+    }
+  }
+  MemSetTypeFlag(pIn1, MEM_Int);
+  break;
+}
+
+#ifndef SQLITE_OMIT_FLOATING_POINT
+/* Opcode: RealAffinity P1 * * * *
+**
+** If register P1 holds an integer convert it to a real value.
+**
+** This opcode is used when extracting information from a column that
+** has REAL affinity.  Such column values may still be stored as
+** integers, for space efficiency, but after extraction we want them
+** to have only a real value.
+*/
+case OP_RealAffinity: {                  /* in1 */
+  pIn1 = &aMem[pOp->p1];
+  if( pIn1->flags & MEM_Int ){
+    sqlite3VdbeMemRealify(pIn1);
+  }
+  break;
+}
+#endif
+
+#ifndef SQLITE_OMIT_CAST
+/* Opcode: Cast P1 P2 * * *
+** Synopsis: affinity(r[P1])
+**
+** Force the value in register P1 to be the type defined by P2.
+** 
+** <ul>
+** <li value="97"> TEXT
+** <li value="98"> BLOB
+** <li value="99"> NUMERIC
+** <li value="100"> INTEGER
+** <li value="101"> REAL
+** </ul>
+**
+** A NULL value is not changed by this routine.  It remains NULL.
+*/
+case OP_Cast: {                  /* in1 */
+  assert( pOp->p2>=SQLITE_AFF_BLOB && pOp->p2<=SQLITE_AFF_REAL );
+  testcase( pOp->p2==SQLITE_AFF_TEXT );
+  testcase( pOp->p2==SQLITE_AFF_BLOB );
+  testcase( pOp->p2==SQLITE_AFF_NUMERIC );
+  testcase( pOp->p2==SQLITE_AFF_INTEGER );
+  testcase( pOp->p2==SQLITE_AFF_REAL );
+  pIn1 = &aMem[pOp->p1];
+  memAboutToChange(p, pIn1);
+  rc = ExpandBlob(pIn1);
+  sqlite3VdbeMemCast(pIn1, pOp->p2, encoding);
+  UPDATE_MAX_BLOBSIZE(pIn1);
+  if( rc ) goto abort_due_to_error;
+  break;
+}
+#endif /* SQLITE_OMIT_CAST */
+
+/* Opcode: Eq P1 P2 P3 P4 P5
+** Synopsis: IF r[P3]==r[P1]
+**
+** Compare the values in register P1 and P3.  If reg(P3)==reg(P1) then
+** jump to address P2.  Or if the SQLITE_STOREP2 flag is set in P5, then
+** store the result of comparison in register P2.
+**
+** The SQLITE_AFF_MASK portion of P5 must be an affinity character -
+** SQLITE_AFF_TEXT, SQLITE_AFF_INTEGER, and so forth. An attempt is made 
+** to coerce both inputs according to this affinity before the
+** comparison is made. If the SQLITE_AFF_MASK is 0x00, then numeric
+** affinity is used. Note that the affinity conversions are stored
+** back into the input registers P1 and P3.  So this opcode can cause
+** persistent changes to registers P1 and P3.
+**
+** Once any conversions have taken place, and neither value is NULL, 
+** the values are compared. If both values are blobs then memcmp() is
+** used to determine the results of the comparison.  If both values
+** are text, then the appropriate collating function specified in
+** P4 is used to do the comparison.  If P4 is not specified then
+** memcmp() is used to compare text string.  If both values are
+** numeric, then a numeric comparison is used. If the two values
+** are of different types, then numbers are considered less than
+** strings and strings are considered less than blobs.
+**
+** If SQLITE_NULLEQ is set in P5 then the result of comparison is always either
+** true or false and is never NULL.  If both operands are NULL then the result
+** of comparison is true.  If either operand is NULL then the result is false.
+** If neither operand is NULL the result is the same as it would be if
+** the SQLITE_NULLEQ flag were omitted from P5.
+**
+** If both SQLITE_STOREP2 and SQLITE_KEEPNULL flags are set then the
+** content of r[P2] is only changed if the new value is NULL or 0 (false).
+** In other words, a prior r[P2] value will not be overwritten by 1 (true).
+*/
+/* Opcode: Ne P1 P2 P3 P4 P5
+** Synopsis: IF r[P3]!=r[P1]
+**
+** This works just like the Eq opcode except that the jump is taken if
+** the operands in registers P1 and P3 are not equal.  See the Eq opcode for
+** additional information.
+**
+** If both SQLITE_STOREP2 and SQLITE_KEEPNULL flags are set then the
+** content of r[P2] is only changed if the new value is NULL or 1 (true).
+** In other words, a prior r[P2] value will not be overwritten by 0 (false).
+*/
+/* Opcode: Lt P1 P2 P3 P4 P5
+** Synopsis: IF r[P3]<r[P1]
+**
+** Compare the values in register P1 and P3.  If reg(P3)<reg(P1) then
+** jump to address P2.  Or if the SQLITE_STOREP2 flag is set in P5 store
+** the result of comparison (0 or 1 or NULL) into register P2.
+**
+** If the SQLITE_JUMPIFNULL bit of P5 is set and either reg(P1) or
+** reg(P3) is NULL then the take the jump.  If the SQLITE_JUMPIFNULL 
+** bit is clear then fall through if either operand is NULL.
+**
+** The SQLITE_AFF_MASK portion of P5 must be an affinity character -
+** SQLITE_AFF_TEXT, SQLITE_AFF_INTEGER, and so forth. An attempt is made 
+** to coerce both inputs according to this affinity before the
+** comparison is made. If the SQLITE_AFF_MASK is 0x00, then numeric
+** affinity is used. Note that the affinity conversions are stored
+** back into the input registers P1 and P3.  So this opcode can cause
+** persistent changes to registers P1 and P3.
+**
+** Once any conversions have taken place, and neither value is NULL, 
+** the values are compared. If both values are blobs then memcmp() is
+** used to determine the results of the comparison.  If both values
+** are text, then the appropriate collating function specified in
+** P4 is  used to do the comparison.  If P4 is not specified then
+** memcmp() is used to compare text string.  If both values are
+** numeric, then a numeric comparison is used. If the two values
+** are of different types, then numbers are considered less than
+** strings and strings are considered less than blobs.
+*/
+/* Opcode: Le P1 P2 P3 P4 P5
+** Synopsis: IF r[P3]<=r[P1]
+**
+** This works just like the Lt opcode except that the jump is taken if
+** the content of register P3 is less than or equal to the content of
+** register P1.  See the Lt opcode for additional information.
+*/
+/* Opcode: Gt P1 P2 P3 P4 P5
+** Synopsis: IF r[P3]>r[P1]
+**
+** This works just like the Lt opcode except that the jump is taken if
+** the content of register P3 is greater than the content of
+** register P1.  See the Lt opcode for additional information.
+*/
+/* Opcode: Ge P1 P2 P3 P4 P5
+** Synopsis: IF r[P3]>=r[P1]
+**
+** This works just like the Lt opcode except that the jump is taken if
+** the content of register P3 is greater than or equal to the content of
+** register P1.  See the Lt opcode for additional information.
+*/
+case OP_Eq:               /* same as TK_EQ, jump, in1, in3 */
+case OP_Ne:               /* same as TK_NE, jump, in1, in3 */
+case OP_Lt:               /* same as TK_LT, jump, in1, in3 */
+case OP_Le:               /* same as TK_LE, jump, in1, in3 */
+case OP_Gt:               /* same as TK_GT, jump, in1, in3 */
+case OP_Ge: {             /* same as TK_GE, jump, in1, in3 */
+  int res, res2;      /* Result of the comparison of pIn1 against pIn3 */
+  char affinity;      /* Affinity to use for comparison */
+  u16 flags1;         /* Copy of initial value of pIn1->flags */
+  u16 flags3;         /* Copy of initial value of pIn3->flags */
+
+  pIn1 = &aMem[pOp->p1];
+  pIn3 = &aMem[pOp->p3];
+  flags1 = pIn1->flags;
+  flags3 = pIn3->flags;
+  if( (flags1 | flags3)&MEM_Null ){
+    /* One or both operands are NULL */
+    if( pOp->p5 & SQLITE_NULLEQ ){
+      /* If SQLITE_NULLEQ is set (which will only happen if the operator is
+      ** OP_Eq or OP_Ne) then take the jump or not depending on whether
+      ** or not both operands are null.
+      */
+      assert( pOp->opcode==OP_Eq || pOp->opcode==OP_Ne );
+      assert( (flags1 & MEM_Cleared)==0 );
+      assert( (pOp->p5 & SQLITE_JUMPIFNULL)==0 );
+      if( (flags1&MEM_Null)!=0
+       && (flags3&MEM_Null)!=0
+       && (flags3&MEM_Cleared)==0
+      ){
+        res = 0;  /* Operands are equal */
+      }else{
+        res = 1;  /* Operands are not equal */
+      }
+    }else{
+      /* SQLITE_NULLEQ is clear and at least one operand is NULL,
+      ** then the result is always NULL.
+      ** The jump is taken if the SQLITE_JUMPIFNULL bit is set.
+      */
+      if( pOp->p5 & SQLITE_STOREP2 ){
+        pOut = &aMem[pOp->p2];
+        iCompare = 1;    /* Operands are not equal */
+        memAboutToChange(p, pOut);
+        MemSetTypeFlag(pOut, MEM_Null);
+        REGISTER_TRACE(pOp->p2, pOut);
+      }else{
+        VdbeBranchTaken(2,3);
+        if( pOp->p5 & SQLITE_JUMPIFNULL ){
+          goto jump_to_p2;
+        }
+      }
+      break;
+    }
+  }else{
+    /* Neither operand is NULL.  Do a comparison. */
+    affinity = pOp->p5 & SQLITE_AFF_MASK;
+    if( affinity>=SQLITE_AFF_NUMERIC ){
+      if( (flags1 | flags3)&MEM_Str ){
+        if( (flags1 & (MEM_Int|MEM_Real|MEM_Str))==MEM_Str ){
+          applyNumericAffinity(pIn1,0);
+          testcase( flags3!=pIn3->flags ); /* Possible if pIn1==pIn3 */
+          flags3 = pIn3->flags;
+        }
+        if( (flags3 & (MEM_Int|MEM_Real|MEM_Str))==MEM_Str ){
+          applyNumericAffinity(pIn3,0);
+        }
+      }
+      /* Handle the common case of integer comparison here, as an
+      ** optimization, to avoid a call to sqlite3MemCompare() */
+      if( (pIn1->flags & pIn3->flags & MEM_Int)!=0 ){
+        if( pIn3->u.i > pIn1->u.i ){ res = +1; goto compare_op; }
+        if( pIn3->u.i < pIn1->u.i ){ res = -1; goto compare_op; }
+        res = 0;
+        goto compare_op;
+      }
+    }else if( affinity==SQLITE_AFF_TEXT ){
+      if( (flags1 & MEM_Str)==0 && (flags1 & (MEM_Int|MEM_Real))!=0 ){
+        testcase( pIn1->flags & MEM_Int );
+        testcase( pIn1->flags & MEM_Real );
+        sqlite3VdbeMemStringify(pIn1, encoding, 1);
+        testcase( (flags1&MEM_Dyn) != (pIn1->flags&MEM_Dyn) );
+        flags1 = (pIn1->flags & ~MEM_TypeMask) | (flags1 & MEM_TypeMask);
+        assert( pIn1!=pIn3 );
+      }
+      if( (flags3 & MEM_Str)==0 && (flags3 & (MEM_Int|MEM_Real))!=0 ){
+        testcase( pIn3->flags & MEM_Int );
+        testcase( pIn3->flags & MEM_Real );
+        sqlite3VdbeMemStringify(pIn3, encoding, 1);
+        testcase( (flags3&MEM_Dyn) != (pIn3->flags&MEM_Dyn) );
+        flags3 = (pIn3->flags & ~MEM_TypeMask) | (flags3 & MEM_TypeMask);
+      }
+    }
+    assert( pOp->p4type==P4_COLLSEQ || pOp->p4.pColl==0 );
+    res = sqlite3MemCompare(pIn3, pIn1, pOp->p4.pColl);
+  }
+compare_op:
+  switch( pOp->opcode ){
+    case OP_Eq:    res2 = res==0;     break;
+    case OP_Ne:    res2 = res;        break;
+    case OP_Lt:    res2 = res<0;      break;
+    case OP_Le:    res2 = res<=0;     break;
+    case OP_Gt:    res2 = res>0;      break;
+    default:       res2 = res>=0;     break;
+  }
+
+  /* Undo any changes made by applyAffinity() to the input registers. */
+  assert( (pIn1->flags & MEM_Dyn) == (flags1 & MEM_Dyn) );
+  pIn1->flags = flags1;
+  assert( (pIn3->flags & MEM_Dyn) == (flags3 & MEM_Dyn) );
+  pIn3->flags = flags3;
+
+  if( pOp->p5 & SQLITE_STOREP2 ){
+    pOut = &aMem[pOp->p2];
+    iCompare = res;
+    res2 = res2!=0;  /* For this path res2 must be exactly 0 or 1 */
+    if( (pOp->p5 & SQLITE_KEEPNULL)!=0 ){
+      /* The KEEPNULL flag prevents OP_Eq from overwriting a NULL with 1
+      ** and prevents OP_Ne from overwriting NULL with 0.  This flag
+      ** is only used in contexts where either:
+      **   (1) op==OP_Eq && (r[P2]==NULL || r[P2]==0)
+      **   (2) op==OP_Ne && (r[P2]==NULL || r[P2]==1)
+      ** Therefore it is not necessary to check the content of r[P2] for
+      ** NULL. */
+      assert( pOp->opcode==OP_Ne || pOp->opcode==OP_Eq );
+      assert( res2==0 || res2==1 );
+      testcase( res2==0 && pOp->opcode==OP_Eq );
+      testcase( res2==1 && pOp->opcode==OP_Eq );
+      testcase( res2==0 && pOp->opcode==OP_Ne );
+      testcase( res2==1 && pOp->opcode==OP_Ne );
+      if( (pOp->opcode==OP_Eq)==res2 ) break;
+    }
+    memAboutToChange(p, pOut);
+    MemSetTypeFlag(pOut, MEM_Int);
+    pOut->u.i = res2;
+    REGISTER_TRACE(pOp->p2, pOut);
+  }else{
+    VdbeBranchTaken(res!=0, (pOp->p5 & SQLITE_NULLEQ)?2:3);
+    if( res2 ){
+      goto jump_to_p2;
+    }
+  }
+  break;
+}
+
+/* Opcode: ElseNotEq * P2 * * *
+**
+** This opcode must immediately follow an OP_Lt or OP_Gt comparison operator.
+** If result of an OP_Eq comparison on the same two operands
+** would have be NULL or false (0), then then jump to P2. 
+** If the result of an OP_Eq comparison on the two previous operands
+** would have been true (1), then fall through.
+*/
+case OP_ElseNotEq: {       /* same as TK_ESCAPE, jump */
+  assert( pOp>aOp );
+  assert( pOp[-1].opcode==OP_Lt || pOp[-1].opcode==OP_Gt );
+  assert( pOp[-1].p5 & SQLITE_STOREP2 );
+  VdbeBranchTaken(iCompare!=0, 2);
+  if( iCompare!=0 ) goto jump_to_p2;
+  break;
+}
+
+
+/* Opcode: Permutation * * * P4 *
+**
+** Set the permutation used by the OP_Compare operator to be the array
+** of integers in P4.
+**
+** The permutation is only valid until the next OP_Compare that has
+** the OPFLAG_PERMUTE bit set in P5. Typically the OP_Permutation should 
+** occur immediately prior to the OP_Compare.
+**
+** The first integer in the P4 integer array is the length of the array
+** and does not become part of the permutation.
+*/
+case OP_Permutation: {
+  assert( pOp->p4type==P4_INTARRAY );
+  assert( pOp->p4.ai );
+  aPermute = pOp->p4.ai + 1;
+  break;
+}
+
+/* Opcode: Compare P1 P2 P3 P4 P5
+** Synopsis: r[P1@P3] <-> r[P2@P3]
+**
+** Compare two vectors of registers in reg(P1)..reg(P1+P3-1) (call this
+** vector "A") and in reg(P2)..reg(P2+P3-1) ("B").  Save the result of
+** the comparison for use by the next OP_Jump instruct.
+**
+** If P5 has the OPFLAG_PERMUTE bit set, then the order of comparison is
+** determined by the most recent OP_Permutation operator.  If the
+** OPFLAG_PERMUTE bit is clear, then register are compared in sequential
+** order.
+**
+** P4 is a KeyInfo structure that defines collating sequences and sort
+** orders for the comparison.  The permutation applies to registers
+** only.  The KeyInfo elements are used sequentially.
+**
+** The comparison is a sort comparison, so NULLs compare equal,
+** NULLs are less than numbers, numbers are less than strings,
+** and strings are less than blobs.
+*/
+case OP_Compare: {
+  int n;
+  int i;
+  int p1;
+  int p2;
+  const KeyInfo *pKeyInfo;
+  int idx;
+  CollSeq *pColl;    /* Collating sequence to use on this term */
+  int bRev;          /* True for DESCENDING sort order */
+
+  if( (pOp->p5 & OPFLAG_PERMUTE)==0 ) aPermute = 0;
+  n = pOp->p3;
+  pKeyInfo = pOp->p4.pKeyInfo;
+  assert( n>0 );
+  assert( pKeyInfo!=0 );
+  p1 = pOp->p1;
+  p2 = pOp->p2;
+#if SQLITE_DEBUG
+  if( aPermute ){
+    int k, mx = 0;
+    for(k=0; k<n; k++) if( aPermute[k]>mx ) mx = aPermute[k];
+    assert( p1>0 && p1+mx<=(p->nMem+1 - p->nCursor)+1 );
+    assert( p2>0 && p2+mx<=(p->nMem+1 - p->nCursor)+1 );
+  }else{
+    assert( p1>0 && p1+n<=(p->nMem+1 - p->nCursor)+1 );
+    assert( p2>0 && p2+n<=(p->nMem+1 - p->nCursor)+1 );
+  }
+#endif /* SQLITE_DEBUG */
+  for(i=0; i<n; i++){
+    idx = aPermute ? aPermute[i] : i;
+    assert( memIsValid(&aMem[p1+idx]) );
+    assert( memIsValid(&aMem[p2+idx]) );
+    REGISTER_TRACE(p1+idx, &aMem[p1+idx]);
+    REGISTER_TRACE(p2+idx, &aMem[p2+idx]);
+    assert( i<pKeyInfo->nField );
+    pColl = pKeyInfo->aColl[i];
+    bRev = pKeyInfo->aSortOrder[i];
+    iCompare = sqlite3MemCompare(&aMem[p1+idx], &aMem[p2+idx], pColl);
+    if( iCompare ){
+      if( bRev ) iCompare = -iCompare;
+      break;
+    }
+  }
+  aPermute = 0;
+  break;
+}
+
+/* Opcode: Jump P1 P2 P3 * *
+**
+** Jump to the instruction at address P1, P2, or P3 depending on whether
+** in the most recent OP_Compare instruction the P1 vector was less than
+** equal to, or greater than the P2 vector, respectively.
+*/
+case OP_Jump: {             /* jump */
+  if( iCompare<0 ){
+    VdbeBranchTaken(0,3); pOp = &aOp[pOp->p1 - 1];
+  }else if( iCompare==0 ){
+    VdbeBranchTaken(1,3); pOp = &aOp[pOp->p2 - 1];
+  }else{
+    VdbeBranchTaken(2,3); pOp = &aOp[pOp->p3 - 1];
+  }
+  break;
+}
+
+/* Opcode: And P1 P2 P3 * *
+** Synopsis: r[P3]=(r[P1] && r[P2])
+**
+** Take the logical AND of the values in registers P1 and P2 and
+** write the result into register P3.
+**
+** If either P1 or P2 is 0 (false) then the result is 0 even if
+** the other input is NULL.  A NULL and true or two NULLs give
+** a NULL output.
+*/
+/* Opcode: Or P1 P2 P3 * *
+** Synopsis: r[P3]=(r[P1] || r[P2])
+**
+** Take the logical OR of the values in register P1 and P2 and
+** store the answer in register P3.
+**
+** If either P1 or P2 is nonzero (true) then the result is 1 (true)
+** even if the other input is NULL.  A NULL and false or two NULLs
+** give a NULL output.
+*/
+case OP_And:              /* same as TK_AND, in1, in2, out3 */
+case OP_Or: {             /* same as TK_OR, in1, in2, out3 */
+  int v1;    /* Left operand:  0==FALSE, 1==TRUE, 2==UNKNOWN or NULL */
+  int v2;    /* Right operand: 0==FALSE, 1==TRUE, 2==UNKNOWN or NULL */
+
+  pIn1 = &aMem[pOp->p1];
+  if( pIn1->flags & MEM_Null ){
+    v1 = 2;
+  }else{
+    v1 = sqlite3VdbeIntValue(pIn1)!=0;
+  }
+  pIn2 = &aMem[pOp->p2];
+  if( pIn2->flags & MEM_Null ){
+    v2 = 2;
+  }else{
+    v2 = sqlite3VdbeIntValue(pIn2)!=0;
+  }
+  if( pOp->opcode==OP_And ){
+    static const unsigned char and_logic[] = { 0, 0, 0, 0, 1, 2, 0, 2, 2 };
+    v1 = and_logic[v1*3+v2];
+  }else{
+    static const unsigned char or_logic[] = { 0, 1, 2, 1, 1, 1, 2, 1, 2 };
+    v1 = or_logic[v1*3+v2];
+  }
+  pOut = &aMem[pOp->p3];
+  if( v1==2 ){
+    MemSetTypeFlag(pOut, MEM_Null);
+  }else{
+    pOut->u.i = v1;
+    MemSetTypeFlag(pOut, MEM_Int);
+  }
+  break;
+}
+
+/* Opcode: Not P1 P2 * * *
+** Synopsis: r[P2]= !r[P1]
+**
+** Interpret the value in register P1 as a boolean value.  Store the
+** boolean complement in register P2.  If the value in register P1 is 
+** NULL, then a NULL is stored in P2.
+*/
+case OP_Not: {                /* same as TK_NOT, in1, out2 */
+  pIn1 = &aMem[pOp->p1];
+  pOut = &aMem[pOp->p2];
+  sqlite3VdbeMemSetNull(pOut);
+  if( (pIn1->flags & MEM_Null)==0 ){
+    pOut->flags = MEM_Int;
+    pOut->u.i = !sqlite3VdbeIntValue(pIn1);
+  }
+  break;
+}
+
+/* Opcode: BitNot P1 P2 * * *
+** Synopsis: r[P1]= ~r[P1]
+**
+** Interpret the content of register P1 as an integer.  Store the
+** ones-complement of the P1 value into register P2.  If P1 holds
+** a NULL then store a NULL in P2.
+*/
+case OP_BitNot: {             /* same as TK_BITNOT, in1, out2 */
+  pIn1 = &aMem[pOp->p1];
+  pOut = &aMem[pOp->p2];
+  sqlite3VdbeMemSetNull(pOut);
+  if( (pIn1->flags & MEM_Null)==0 ){
+    pOut->flags = MEM_Int;
+    pOut->u.i = ~sqlite3VdbeIntValue(pIn1);
+  }
+  break;
+}
+
+/* Opcode: Once P1 P2 * * *
+**
+** If the P1 value is equal to the P1 value on the OP_Init opcode at
+** instruction 0, then jump to P2.  If the two P1 values differ, then
+** set the P1 value on this opcode to equal the P1 value on the OP_Init
+** and fall through.
+*/
+case OP_Once: {             /* jump */
+  assert( p->aOp[0].opcode==OP_Init );
+  VdbeBranchTaken(p->aOp[0].p1==pOp->p1, 2);
+  if( p->aOp[0].p1==pOp->p1 ){
+    goto jump_to_p2;
+  }else{
+    pOp->p1 = p->aOp[0].p1;
+  }
+  break;
+}
+
+/* Opcode: If P1 P2 P3 * *
+**
+** Jump to P2 if the value in register P1 is true.  The value
+** is considered true if it is numeric and non-zero.  If the value
+** in P1 is NULL then take the jump if and only if P3 is non-zero.
+*/
+/* Opcode: IfNot P1 P2 P3 * *
+**
+** Jump to P2 if the value in register P1 is False.  The value
+** is considered false if it has a numeric value of zero.  If the value
+** in P1 is NULL then take the jump if and only if P3 is non-zero.
+*/
+case OP_If:                 /* jump, in1 */
+case OP_IfNot: {            /* jump, in1 */
+  int c;
+  pIn1 = &aMem[pOp->p1];
+  if( pIn1->flags & MEM_Null ){
+    c = pOp->p3;
+  }else{
+#ifdef SQLITE_OMIT_FLOATING_POINT
+    c = sqlite3VdbeIntValue(pIn1)!=0;
+#else
+    c = sqlite3VdbeRealValue(pIn1)!=0.0;
+#endif
+    if( pOp->opcode==OP_IfNot ) c = !c;
+  }
+  VdbeBranchTaken(c!=0, 2);
+  if( c ){
+    goto jump_to_p2;
+  }
+  break;
+}
+
+/* Opcode: IsNull P1 P2 * * *
+** Synopsis: if r[P1]==NULL goto P2
+**
+** Jump to P2 if the value in register P1 is NULL.
+*/
+case OP_IsNull: {            /* same as TK_ISNULL, jump, in1 */
+  pIn1 = &aMem[pOp->p1];
+  VdbeBranchTaken( (pIn1->flags & MEM_Null)!=0, 2);
+  if( (pIn1->flags & MEM_Null)!=0 ){
+    goto jump_to_p2;
+  }
+  break;
+}
+
+/* Opcode: NotNull P1 P2 * * *
+** Synopsis: if r[P1]!=NULL goto P2
+**
+** Jump to P2 if the value in register P1 is not NULL.  
+*/
+case OP_NotNull: {            /* same as TK_NOTNULL, jump, in1 */
+  pIn1 = &aMem[pOp->p1];
+  VdbeBranchTaken( (pIn1->flags & MEM_Null)==0, 2);
+  if( (pIn1->flags & MEM_Null)==0 ){
+    goto jump_to_p2;
+  }
+  break;
+}
+
+/* Opcode: Column P1 P2 P3 P4 P5
+** Synopsis: r[P3]=PX
+**
+** Interpret the data that cursor P1 points to as a structure built using
+** the MakeRecord instruction.  (See the MakeRecord opcode for additional
+** information about the format of the data.)  Extract the P2-th column
+** from this record.  If there are less that (P2+1) 
+** values in the record, extract a NULL.
+**
+** The value extracted is stored in register P3.
+**
+** If the column contains fewer than P2 fields, then extract a NULL.  Or,
+** if the P4 argument is a P4_MEM use the value of the P4 argument as
+** the result.
+**
+** If the OPFLAG_CLEARCACHE bit is set on P5 and P1 is a pseudo-table cursor,
+** then the cache of the cursor is reset prior to extracting the column.
+** The first OP_Column against a pseudo-table after the value of the content
+** register has changed should have this bit set.
+**
+** If the OPFLAG_LENGTHARG and OPFLAG_TYPEOFARG bits are set on P5 when
+** the result is guaranteed to only be used as the argument of a length()
+** or typeof() function, respectively.  The loading of large blobs can be
+** skipped for length() and all content loading can be skipped for typeof().
+*/
+case OP_Column: {
+  int p2;            /* column number to retrieve */
+  VdbeCursor *pC;    /* The VDBE cursor */
+  BtCursor *pCrsr;   /* The BTree cursor */
+  u32 *aOffset;      /* aOffset[i] is offset to start of data for i-th column */
+  int len;           /* The length of the serialized data for the column */
+  int i;             /* Loop counter */
+  Mem *pDest;        /* Where to write the extracted value */
+  Mem sMem;          /* For storing the record being decoded */
+  const u8 *zData;   /* Part of the record being decoded */
+  const u8 *zHdr;    /* Next unparsed byte of the header */
+  const u8 *zEndHdr; /* Pointer to first byte after the header */
+  u32 offset;        /* Offset into the data */
+  u64 offset64;      /* 64-bit offset */
+  u32 avail;         /* Number of bytes of available data */
+  u32 t;             /* A type code from the record header */
+  Mem *pReg;         /* PseudoTable input register */
+
+  pC = p->apCsr[pOp->p1];
+  p2 = pOp->p2;
+
+  /* If the cursor cache is stale, bring it up-to-date */
+  rc = sqlite3VdbeCursorMoveto(&pC, &p2);
+  if( rc ) goto abort_due_to_error;
+
+  assert( pOp->p3>0 && pOp->p3<=(p->nMem+1 - p->nCursor) );
+  pDest = &aMem[pOp->p3];
+  memAboutToChange(p, pDest);
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  assert( pC!=0 );
+  assert( p2<pC->nField );
+  aOffset = pC->aOffset;
+  assert( pC->eCurType!=CURTYPE_VTAB );
+  assert( pC->eCurType!=CURTYPE_PSEUDO || pC->nullRow );
+  assert( pC->eCurType!=CURTYPE_SORTER );
+  pCrsr = pC->uc.pCursor;
+
+  if( pC->cacheStatus!=p->cacheCtr ){                /*OPTIMIZATION-IF-FALSE*/
+    if( pC->nullRow ){
+      if( pC->eCurType==CURTYPE_PSEUDO ){
+        assert( pC->uc.pseudoTableReg>0 );
+        pReg = &aMem[pC->uc.pseudoTableReg];
+        assert( pReg->flags & MEM_Blob );
+        assert( memIsValid(pReg) );
+        pC->payloadSize = pC->szRow = avail = pReg->n;
+        pC->aRow = (u8*)pReg->z;
+      }else{
+        sqlite3VdbeMemSetNull(pDest);
+        goto op_column_out;
+      }
+    }else{
+      assert( pC->eCurType==CURTYPE_BTREE );
+      assert( pCrsr );
+      assert( sqlite3BtreeCursorIsValid(pCrsr) );
+      pC->payloadSize = sqlite3BtreePayloadSize(pCrsr);
+      pC->aRow = sqlite3BtreePayloadFetch(pCrsr, &avail);
+      assert( avail<=65536 );  /* Maximum page size is 64KiB */
+      if( pC->payloadSize <= (u32)avail ){
+        pC->szRow = pC->payloadSize;
+      }else if( pC->payloadSize > (u32)db->aLimit[SQLITE_LIMIT_LENGTH] ){
+        goto too_big;
+      }else{
+        pC->szRow = avail;
+      }
+    }
+    pC->cacheStatus = p->cacheCtr;
+    pC->iHdrOffset = getVarint32(pC->aRow, offset);
+    pC->nHdrParsed = 0;
+    aOffset[0] = offset;
+
+
+    if( avail<offset ){      /*OPTIMIZATION-IF-FALSE*/
+      /* pC->aRow does not have to hold the entire row, but it does at least
+      ** need to cover the header of the record.  If pC->aRow does not contain
+      ** the complete header, then set it to zero, forcing the header to be
+      ** dynamically allocated. */
+      pC->aRow = 0;
+      pC->szRow = 0;
+
+      /* Make sure a corrupt database has not given us an oversize header.
+      ** Do this now to avoid an oversize memory allocation.
+      **
+      ** Type entries can be between 1 and 5 bytes each.  But 4 and 5 byte
+      ** types use so much data space that there can only be 4096 and 32 of
+      ** them, respectively.  So the maximum header length results from a
+      ** 3-byte type for each of the maximum of 32768 columns plus three
+      ** extra bytes for the header length itself.  32768*3 + 3 = 98307.
+      */
+      if( offset > 98307 || offset > pC->payloadSize ){
+        rc = SQLITE_CORRUPT_BKPT;
+        goto abort_due_to_error;
+      }
+    }else if( offset>0 ){ /*OPTIMIZATION-IF-TRUE*/
+      /* The following goto is an optimization.  It can be omitted and
+      ** everything will still work.  But OP_Column is measurably faster
+      ** by skipping the subsequent conditional, which is always true.
+      */
+      zData = pC->aRow;
+      assert( pC->nHdrParsed<=p2 );         /* Conditional skipped */
+      goto op_column_read_header;
+    }
+  }
+
+  /* Make sure at least the first p2+1 entries of the header have been
+  ** parsed and valid information is in aOffset[] and pC->aType[].
+  */
+  if( pC->nHdrParsed<=p2 ){
+    /* If there is more header available for parsing in the record, try
+    ** to extract additional fields up through the p2+1-th field 
+    */
+    if( pC->iHdrOffset<aOffset[0] ){
+      /* Make sure zData points to enough of the record to cover the header. */
+      if( pC->aRow==0 ){
+        memset(&sMem, 0, sizeof(sMem));
+        rc = sqlite3VdbeMemFromBtree(pCrsr, 0, aOffset[0], !pC->isTable, &sMem);
+        if( rc!=SQLITE_OK ) goto abort_due_to_error;
+        zData = (u8*)sMem.z;
+      }else{
+        zData = pC->aRow;
+      }
+  
+      /* Fill in pC->aType[i] and aOffset[i] values through the p2-th field. */
+    op_column_read_header:
+      i = pC->nHdrParsed;
+      offset64 = aOffset[i];
+      zHdr = zData + pC->iHdrOffset;
+      zEndHdr = zData + aOffset[0];
+      do{
+        if( (t = zHdr[0])<0x80 ){
+          zHdr++;
+          offset64 += sqlite3VdbeOneByteSerialTypeLen(t);
+        }else{
+          zHdr += sqlite3GetVarint32(zHdr, &t);
+          offset64 += sqlite3VdbeSerialTypeLen(t);
+        }
+        pC->aType[i++] = t;
+        aOffset[i] = (u32)(offset64 & 0xffffffff);
+      }while( i<=p2 && zHdr<zEndHdr );
+
+      /* The record is corrupt if any of the following are true:
+      ** (1) the bytes of the header extend past the declared header size
+      ** (2) the entire header was used but not all data was used
+      ** (3) the end of the data extends beyond the end of the record.
+      */
+      if( (zHdr>=zEndHdr && (zHdr>zEndHdr || offset64!=pC->payloadSize))
+       || (offset64 > pC->payloadSize)
+      ){
+        if( pC->aRow==0 ) sqlite3VdbeMemRelease(&sMem);
+        rc = SQLITE_CORRUPT_BKPT;
+        goto abort_due_to_error;
+      }
+
+      pC->nHdrParsed = i;
+      pC->iHdrOffset = (u32)(zHdr - zData);
+      if( pC->aRow==0 ) sqlite3VdbeMemRelease(&sMem);
+    }else{
+      t = 0;
+    }
+
+    /* If after trying to extract new entries from the header, nHdrParsed is
+    ** still not up to p2, that means that the record has fewer than p2
+    ** columns.  So the result will be either the default value or a NULL.
+    */
+    if( pC->nHdrParsed<=p2 ){
+      if( pOp->p4type==P4_MEM ){
+        sqlite3VdbeMemShallowCopy(pDest, pOp->p4.pMem, MEM_Static);
+      }else{
+        sqlite3VdbeMemSetNull(pDest);
+      }
+      goto op_column_out;
+    }
+  }else{
+    t = pC->aType[p2];
+  }
+
+  /* Extract the content for the p2+1-th column.  Control can only
+  ** reach this point if aOffset[p2], aOffset[p2+1], and pC->aType[p2] are
+  ** all valid.
+  */
+  assert( p2<pC->nHdrParsed );
+  assert( rc==SQLITE_OK );
+  assert( sqlite3VdbeCheckMemInvariants(pDest) );
+  if( VdbeMemDynamic(pDest) ){
+    sqlite3VdbeMemSetNull(pDest);
+  }
+  assert( t==pC->aType[p2] );
+  if( pC->szRow>=aOffset[p2+1] ){
+    /* This is the common case where the desired content fits on the original
+    ** page - where the content is not on an overflow page */
+    zData = pC->aRow + aOffset[p2];
+    if( t<12 ){
+      sqlite3VdbeSerialGet(zData, t, pDest);
+    }else{
+      /* If the column value is a string, we need a persistent value, not
+      ** a MEM_Ephem value.  This branch is a fast short-cut that is equivalent
+      ** to calling sqlite3VdbeSerialGet() and sqlite3VdbeDeephemeralize().
+      */
+      static const u16 aFlag[] = { MEM_Blob, MEM_Str|MEM_Term };
+      pDest->n = len = (t-12)/2;
+      pDest->enc = encoding;
+      if( pDest->szMalloc < len+2 ){
+        pDest->flags = MEM_Null;
+        if( sqlite3VdbeMemGrow(pDest, len+2, 0) ) goto no_mem;
+      }else{
+        pDest->z = pDest->zMalloc;
+      }
+      memcpy(pDest->z, zData, len);
+      pDest->z[len] = 0;
+      pDest->z[len+1] = 0;
+      pDest->flags = aFlag[t&1];
+    }
+  }else{
+    pDest->enc = encoding;
+    /* This branch happens only when content is on overflow pages */
+    if( ((pOp->p5 & (OPFLAG_LENGTHARG|OPFLAG_TYPEOFARG))!=0
+          && ((t>=12 && (t&1)==0) || (pOp->p5 & OPFLAG_TYPEOFARG)!=0))
+     || (len = sqlite3VdbeSerialTypeLen(t))==0
+    ){
+      /* Content is irrelevant for
+      **    1. the typeof() function,
+      **    2. the length(X) function if X is a blob, and
+      **    3. if the content length is zero.
+      ** So we might as well use bogus content rather than reading
+      ** content from disk. */
+      static u8 aZero[8];  /* This is the bogus content */
+      sqlite3VdbeSerialGet(aZero, t, pDest);
+    }else{
+      rc = sqlite3VdbeMemFromBtree(pCrsr, aOffset[p2], len, !pC->isTable,
+                                   pDest);
+      if( rc!=SQLITE_OK ) goto abort_due_to_error;
+      sqlite3VdbeSerialGet((const u8*)pDest->z, t, pDest);
+      pDest->flags &= ~MEM_Ephem;
+    }
+  }
+
+op_column_out:
+  UPDATE_MAX_BLOBSIZE(pDest);
+  REGISTER_TRACE(pOp->p3, pDest);
+  break;
+}
+
+/* Opcode: Affinity P1 P2 * P4 *
+** Synopsis: affinity(r[P1@P2])
+**
+** Apply affinities to a range of P2 registers starting with P1.
+**
+** P4 is a string that is P2 characters long. The nth character of the
+** string indicates the column affinity that should be used for the nth
+** memory cell in the range.
+*/
+case OP_Affinity: {
+  const char *zAffinity;   /* The affinity to be applied */
+  char cAff;               /* A single character of affinity */
+
+  zAffinity = pOp->p4.z;
+  assert( zAffinity!=0 );
+  assert( zAffinity[pOp->p2]==0 );
+  pIn1 = &aMem[pOp->p1];
+  while( (cAff = *(zAffinity++))!=0 ){
+    assert( pIn1 <= &p->aMem[(p->nMem+1 - p->nCursor)] );
+    assert( memIsValid(pIn1) );
+    applyAffinity(pIn1, cAff, encoding);
+    pIn1++;
+  }
+  break;
+}
+
+/* Opcode: MakeRecord P1 P2 P3 P4 *
+** Synopsis: r[P3]=mkrec(r[P1@P2])
+**
+** Convert P2 registers beginning with P1 into the [record format]
+** use as a data record in a database table or as a key
+** in an index.  The OP_Column opcode can decode the record later.
+**
+** P4 may be a string that is P2 characters long.  The nth character of the
+** string indicates the column affinity that should be used for the nth
+** field of the index key.
+**
+** The mapping from character to affinity is given by the SQLITE_AFF_
+** macros defined in sqliteInt.h.
+**
+** If P4 is NULL then all index fields have the affinity BLOB.
+*/
+case OP_MakeRecord: {
+  u8 *zNewRecord;        /* A buffer to hold the data for the new record */
+  Mem *pRec;             /* The new record */
+  u64 nData;             /* Number of bytes of data space */
+  int nHdr;              /* Number of bytes of header space */
+  i64 nByte;             /* Data space required for this record */
+  i64 nZero;             /* Number of zero bytes at the end of the record */
+  int nVarint;           /* Number of bytes in a varint */
+  u32 serial_type;       /* Type field */
+  Mem *pData0;           /* First field to be combined into the record */
+  Mem *pLast;            /* Last field of the record */
+  int nField;            /* Number of fields in the record */
+  char *zAffinity;       /* The affinity string for the record */
+  int file_format;       /* File format to use for encoding */
+  int i;                 /* Space used in zNewRecord[] header */
+  int j;                 /* Space used in zNewRecord[] content */
+  u32 len;               /* Length of a field */
+
+  /* Assuming the record contains N fields, the record format looks
+  ** like this:
+  **
+  ** ------------------------------------------------------------------------
+  ** | hdr-size | type 0 | type 1 | ... | type N-1 | data0 | ... | data N-1 | 
+  ** ------------------------------------------------------------------------
+  **
+  ** Data(0) is taken from register P1.  Data(1) comes from register P1+1
+  ** and so forth.
+  **
+  ** Each type field is a varint representing the serial type of the 
+  ** corresponding data element (see sqlite3VdbeSerialType()). The
+  ** hdr-size field is also a varint which is the offset from the beginning
+  ** of the record to data0.
+  */
+  nData = 0;         /* Number of bytes of data space */
+  nHdr = 0;          /* Number of bytes of header space */
+  nZero = 0;         /* Number of zero bytes at the end of the record */
+  nField = pOp->p1;
+  zAffinity = pOp->p4.z;
+  assert( nField>0 && pOp->p2>0 && pOp->p2+nField<=(p->nMem+1 - p->nCursor)+1 );
+  pData0 = &aMem[nField];
+  nField = pOp->p2;
+  pLast = &pData0[nField-1];
+  file_format = p->minWriteFileFormat;
+
+  /* Identify the output register */
+  assert( pOp->p3<pOp->p1 || pOp->p3>=pOp->p1+pOp->p2 );
+  pOut = &aMem[pOp->p3];
+  memAboutToChange(p, pOut);
+
+  /* Apply the requested affinity to all inputs
+  */
+  assert( pData0<=pLast );
+  if( zAffinity ){
+    pRec = pData0;
+    do{
+      applyAffinity(pRec++, *(zAffinity++), encoding);
+      assert( zAffinity[0]==0 || pRec<=pLast );
+    }while( zAffinity[0] );
+  }
+
+  /* Loop through the elements that will make up the record to figure
+  ** out how much space is required for the new record.
+  */
+  pRec = pLast;
+  do{
+    assert( memIsValid(pRec) );
+    pRec->uTemp = serial_type = sqlite3VdbeSerialType(pRec, file_format, &len);
+    if( pRec->flags & MEM_Zero ){
+      if( nData ){
+        if( sqlite3VdbeMemExpandBlob(pRec) ) goto no_mem;
+      }else{
+        nZero += pRec->u.nZero;
+        len -= pRec->u.nZero;
+      }
+    }
+    nData += len;
+    testcase( serial_type==127 );
+    testcase( serial_type==128 );
+    nHdr += serial_type<=127 ? 1 : sqlite3VarintLen(serial_type);
+    if( pRec==pData0 ) break;
+    pRec--;
+  }while(1);
+
+  /* EVIDENCE-OF: R-22564-11647 The header begins with a single varint
+  ** which determines the total number of bytes in the header. The varint
+  ** value is the size of the header in bytes including the size varint
+  ** itself. */
+  testcase( nHdr==126 );
+  testcase( nHdr==127 );
+  if( nHdr<=126 ){
+    /* The common case */
+    nHdr += 1;
+  }else{
+    /* Rare case of a really large header */
+    nVarint = sqlite3VarintLen(nHdr);
+    nHdr += nVarint;
+    if( nVarint<sqlite3VarintLen(nHdr) ) nHdr++;
+  }
+  nByte = nHdr+nData;
+  if( nByte+nZero>db->aLimit[SQLITE_LIMIT_LENGTH] ){
+    goto too_big;
+  }
+
+  /* Make sure the output register has a buffer large enough to store 
+  ** the new record. The output register (pOp->p3) is not allowed to
+  ** be one of the input registers (because the following call to
+  ** sqlite3VdbeMemClearAndResize() could clobber the value before it is used).
+  */
+  if( sqlite3VdbeMemClearAndResize(pOut, (int)nByte) ){
+    goto no_mem;
+  }
+  zNewRecord = (u8 *)pOut->z;
+
+  /* Write the record */
+  i = putVarint32(zNewRecord, nHdr);
+  j = nHdr;
+  assert( pData0<=pLast );
+  pRec = pData0;
+  do{
+    serial_type = pRec->uTemp;
+    /* EVIDENCE-OF: R-06529-47362 Following the size varint are one or more
+    ** additional varints, one per column. */
+    i += putVarint32(&zNewRecord[i], serial_type);            /* serial type */
+    /* EVIDENCE-OF: R-64536-51728 The values for each column in the record
+    ** immediately follow the header. */
+    j += sqlite3VdbeSerialPut(&zNewRecord[j], pRec, serial_type); /* content */
+  }while( (++pRec)<=pLast );
+  assert( i==nHdr );
+  assert( j==nByte );
+
+  assert( pOp->p3>0 && pOp->p3<=(p->nMem+1 - p->nCursor) );
+  pOut->n = (int)nByte;
+  pOut->flags = MEM_Blob;
+  if( nZero ){
+    pOut->u.nZero = nZero;
+    pOut->flags |= MEM_Zero;
+  }
+  pOut->enc = SQLITE_UTF8;  /* In case the blob is ever converted to text */
+  REGISTER_TRACE(pOp->p3, pOut);
+  UPDATE_MAX_BLOBSIZE(pOut);
+  break;
+}
+
+/* Opcode: Count P1 P2 * * *
+** Synopsis: r[P2]=count()
+**
+** Store the number of entries (an integer value) in the table or index 
+** opened by cursor P1 in register P2
+*/
+#ifndef SQLITE_OMIT_BTREECOUNT
+case OP_Count: {         /* out2 */
+  i64 nEntry;
+  BtCursor *pCrsr;
+
+  assert( p->apCsr[pOp->p1]->eCurType==CURTYPE_BTREE );
+  pCrsr = p->apCsr[pOp->p1]->uc.pCursor;
+  assert( pCrsr );
+  nEntry = 0;  /* Not needed.  Only used to silence a warning. */
+  rc = sqlite3BtreeCount(pCrsr, &nEntry);
+  if( rc ) goto abort_due_to_error;
+  pOut = out2Prerelease(p, pOp);
+  pOut->u.i = nEntry;
+  break;
+}
+#endif
+
+/* Opcode: Savepoint P1 * * P4 *
+**
+** Open, release or rollback the savepoint named by parameter P4, depending
+** on the value of P1. To open a new savepoint, P1==0. To release (commit) an
+** existing savepoint, P1==1, or to rollback an existing savepoint P1==2.
+*/
+case OP_Savepoint: {
+  int p1;                         /* Value of P1 operand */
+  char *zName;                    /* Name of savepoint */
+  int nName;
+  Savepoint *pNew;
+  Savepoint *pSavepoint;
+  Savepoint *pTmp;
+  int iSavepoint;
+  int ii;
+
+  p1 = pOp->p1;
+  zName = pOp->p4.z;
+
+  /* Assert that the p1 parameter is valid. Also that if there is no open
+  ** transaction, then there cannot be any savepoints. 
+  */
+  assert( db->pSavepoint==0 || db->autoCommit==0 );
+  assert( p1==SAVEPOINT_BEGIN||p1==SAVEPOINT_RELEASE||p1==SAVEPOINT_ROLLBACK );
+  assert( db->pSavepoint || db->isTransactionSavepoint==0 );
+  assert( checkSavepointCount(db) );
+  assert( p->bIsReader );
+
+  if( p1==SAVEPOINT_BEGIN ){
+    if( db->nVdbeWrite>0 ){
+      /* A new savepoint cannot be created if there are active write 
+      ** statements (i.e. open read/write incremental blob handles).
+      */
+      sqlite3VdbeError(p, "cannot open savepoint - SQL statements in progress");
+      rc = SQLITE_BUSY;
+    }else{
+      nName = sqlite3Strlen30(zName);
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+      /* This call is Ok even if this savepoint is actually a transaction
+      ** savepoint (and therefore should not prompt xSavepoint()) callbacks.
+      ** If this is a transaction savepoint being opened, it is guaranteed
+      ** that the db->aVTrans[] array is empty.  */
+      assert( db->autoCommit==0 || db->nVTrans==0 );
+      rc = sqlite3VtabSavepoint(db, SAVEPOINT_BEGIN,
+                                db->nStatement+db->nSavepoint);
+      if( rc!=SQLITE_OK ) goto abort_due_to_error;
+#endif
+
+      /* Create a new savepoint structure. */
+      pNew = sqlite3DbMallocRawNN(db, sizeof(Savepoint)+nName+1);
+      if( pNew ){
+        pNew->zName = (char *)&pNew[1];
+        memcpy(pNew->zName, zName, nName+1);
+    
+        /* If there is no open transaction, then mark this as a special
+        ** "transaction savepoint". */
+        if( db->autoCommit ){
+          db->autoCommit = 0;
+          db->isTransactionSavepoint = 1;
+        }else{
+          db->nSavepoint++;
+        }
+
+        /* Link the new savepoint into the database handle's list. */
+        pNew->pNext = db->pSavepoint;
+        db->pSavepoint = pNew;
+        pNew->nDeferredCons = db->nDeferredCons;
+        pNew->nDeferredImmCons = db->nDeferredImmCons;
+      }
+    }
+  }else{
+    iSavepoint = 0;
+
+    /* Find the named savepoint. If there is no such savepoint, then an
+    ** an error is returned to the user.  */
+    for(
+      pSavepoint = db->pSavepoint; 
+      pSavepoint && sqlite3StrICmp(pSavepoint->zName, zName);
+      pSavepoint = pSavepoint->pNext
+    ){
+      iSavepoint++;
+    }
+    if( !pSavepoint ){
+      sqlite3VdbeError(p, "no such savepoint: %s", zName);
+      rc = SQLITE_ERROR;
+    }else if( db->nVdbeWrite>0 && p1==SAVEPOINT_RELEASE ){
+      /* It is not possible to release (commit) a savepoint if there are 
+      ** active write statements.
+      */
+      sqlite3VdbeError(p, "cannot release savepoint - "
+                          "SQL statements in progress");
+      rc = SQLITE_BUSY;
+    }else{
+
+      /* Determine whether or not this is a transaction savepoint. If so,
+      ** and this is a RELEASE command, then the current transaction 
+      ** is committed. 
+      */
+      int isTransaction = pSavepoint->pNext==0 && db->isTransactionSavepoint;
+      if( isTransaction && p1==SAVEPOINT_RELEASE ){
+        if( (rc = sqlite3VdbeCheckFk(p, 1))!=SQLITE_OK ){
+          goto vdbe_return;
+        }
+        db->autoCommit = 1;
+        if( sqlite3VdbeHalt(p)==SQLITE_BUSY ){
+          p->pc = (int)(pOp - aOp);
+          db->autoCommit = 0;
+          p->rc = rc = SQLITE_BUSY;
+          goto vdbe_return;
+        }
+        db->isTransactionSavepoint = 0;
+        rc = p->rc;
+      }else{
+        int isSchemaChange;
+        iSavepoint = db->nSavepoint - iSavepoint - 1;
+        if( p1==SAVEPOINT_ROLLBACK ){
+          isSchemaChange = (db->flags & SQLITE_InternChanges)!=0;
+          for(ii=0; ii<db->nDb; ii++){
+            rc = sqlite3BtreeTripAllCursors(db->aDb[ii].pBt,
+                                       SQLITE_ABORT_ROLLBACK,
+                                       isSchemaChange==0);
+            if( rc!=SQLITE_OK ) goto abort_due_to_error;
+          }
+        }else{
+          isSchemaChange = 0;
+        }
+        for(ii=0; ii<db->nDb; ii++){
+          rc = sqlite3BtreeSavepoint(db->aDb[ii].pBt, p1, iSavepoint);
+          if( rc!=SQLITE_OK ){
+            goto abort_due_to_error;
+          }
+        }
+        if( isSchemaChange ){
+          sqlite3ExpirePreparedStatements(db);
+          sqlite3ResetAllSchemasOfConnection(db);
+          db->flags = (db->flags | SQLITE_InternChanges);
+        }
+      }
+  
+      /* Regardless of whether this is a RELEASE or ROLLBACK, destroy all 
+      ** savepoints nested inside of the savepoint being operated on. */
+      while( db->pSavepoint!=pSavepoint ){
+        pTmp = db->pSavepoint;
+        db->pSavepoint = pTmp->pNext;
+        sqlite3DbFree(db, pTmp);
+        db->nSavepoint--;
+      }
+
+      /* If it is a RELEASE, then destroy the savepoint being operated on 
+      ** too. If it is a ROLLBACK TO, then set the number of deferred 
+      ** constraint violations present in the database to the value stored
+      ** when the savepoint was created.  */
+      if( p1==SAVEPOINT_RELEASE ){
+        assert( pSavepoint==db->pSavepoint );
+        db->pSavepoint = pSavepoint->pNext;
+        sqlite3DbFree(db, pSavepoint);
+        if( !isTransaction ){
+          db->nSavepoint--;
+        }
+      }else{
+        db->nDeferredCons = pSavepoint->nDeferredCons;
+        db->nDeferredImmCons = pSavepoint->nDeferredImmCons;
+      }
+
+      if( !isTransaction || p1==SAVEPOINT_ROLLBACK ){
+        rc = sqlite3VtabSavepoint(db, p1, iSavepoint);
+        if( rc!=SQLITE_OK ) goto abort_due_to_error;
+      }
+    }
+  }
+  if( rc ) goto abort_due_to_error;
+
+  break;
+}
+
+/* Opcode: AutoCommit P1 P2 * * *
+**
+** Set the database auto-commit flag to P1 (1 or 0). If P2 is true, roll
+** back any currently active btree transactions. If there are any active
+** VMs (apart from this one), then a ROLLBACK fails.  A COMMIT fails if
+** there are active writing VMs or active VMs that use shared cache.
+**
+** This instruction causes the VM to halt.
+*/
+case OP_AutoCommit: {
+  int desiredAutoCommit;
+  int iRollback;
+
+  desiredAutoCommit = pOp->p1;
+  iRollback = pOp->p2;
+  assert( desiredAutoCommit==1 || desiredAutoCommit==0 );
+  assert( desiredAutoCommit==1 || iRollback==0 );
+  assert( db->nVdbeActive>0 );  /* At least this one VM is active */
+  assert( p->bIsReader );
+
+  if( desiredAutoCommit!=db->autoCommit ){
+    if( iRollback ){
+      assert( desiredAutoCommit==1 );
+      sqlite3RollbackAll(db, SQLITE_ABORT_ROLLBACK);
+      db->autoCommit = 1;
+    }else if( desiredAutoCommit && db->nVdbeWrite>0 ){
+      /* If this instruction implements a COMMIT and other VMs are writing
+      ** return an error indicating that the other VMs must complete first. 
+      */
+      sqlite3VdbeError(p, "cannot commit transaction - "
+                          "SQL statements in progress");
+      rc = SQLITE_BUSY;
+      goto abort_due_to_error;
+    }else if( (rc = sqlite3VdbeCheckFk(p, 1))!=SQLITE_OK ){
+      goto vdbe_return;
+    }else{
+      db->autoCommit = (u8)desiredAutoCommit;
+    }
+    if( sqlite3VdbeHalt(p)==SQLITE_BUSY ){
+      p->pc = (int)(pOp - aOp);
+      db->autoCommit = (u8)(1-desiredAutoCommit);
+      p->rc = rc = SQLITE_BUSY;
+      goto vdbe_return;
+    }
+    assert( db->nStatement==0 );
+    sqlite3CloseSavepoints(db);
+    if( p->rc==SQLITE_OK ){
+      rc = SQLITE_DONE;
+    }else{
+      rc = SQLITE_ERROR;
+    }
+    goto vdbe_return;
+  }else{
+    sqlite3VdbeError(p,
+        (!desiredAutoCommit)?"cannot start a transaction within a transaction":(
+        (iRollback)?"cannot rollback - no transaction is active":
+                   "cannot commit - no transaction is active"));
+         
+    rc = SQLITE_ERROR;
+    goto abort_due_to_error;
+  }
+  break;
+}
+
+/* Opcode: Transaction P1 P2 P3 P4 P5
+**
+** Begin a transaction on database P1 if a transaction is not already
+** active.
+** If P2 is non-zero, then a write-transaction is started, or if a 
+** read-transaction is already active, it is upgraded to a write-transaction.
+** If P2 is zero, then a read-transaction is started.
+**
+** P1 is the index of the database file on which the transaction is
+** started.  Index 0 is the main database file and index 1 is the
+** file used for temporary tables.  Indices of 2 or more are used for
+** attached databases.
+**
+** If a write-transaction is started and the Vdbe.usesStmtJournal flag is
+** true (this flag is set if the Vdbe may modify more than one row and may
+** throw an ABORT exception), a statement transaction may also be opened.
+** More specifically, a statement transaction is opened iff the database
+** connection is currently not in autocommit mode, or if there are other
+** active statements. A statement transaction allows the changes made by this
+** VDBE to be rolled back after an error without having to roll back the
+** entire transaction. If no error is encountered, the statement transaction
+** will automatically commit when the VDBE halts.
+**
+** If P5!=0 then this opcode also checks the schema cookie against P3
+** and the schema generation counter against P4.
+** The cookie changes its value whenever the database schema changes.
+** This operation is used to detect when that the cookie has changed
+** and that the current process needs to reread the schema.  If the schema
+** cookie in P3 differs from the schema cookie in the database header or
+** if the schema generation counter in P4 differs from the current
+** generation counter, then an SQLITE_SCHEMA error is raised and execution
+** halts.  The sqlite3_step() wrapper function might then reprepare the
+** statement and rerun it from the beginning.
+*/
+case OP_Transaction: {
+  Btree *pBt;
+  int iMeta;
+  int iGen;
+
+  assert( p->bIsReader );
+  assert( p->readOnly==0 || pOp->p2==0 );
+  assert( pOp->p1>=0 && pOp->p1<db->nDb );
+  assert( DbMaskTest(p->btreeMask, pOp->p1) );
+  if( pOp->p2 && (db->flags & SQLITE_QueryOnly)!=0 ){
+    rc = SQLITE_READONLY;
+    goto abort_due_to_error;
+  }
+  pBt = db->aDb[pOp->p1].pBt;
+
+  if( pBt ){
+    rc = sqlite3BtreeBeginTrans(pBt, pOp->p2);
+    testcase( rc==SQLITE_BUSY_SNAPSHOT );
+    testcase( rc==SQLITE_BUSY_RECOVERY );
+    if( rc!=SQLITE_OK ){
+      if( (rc&0xff)==SQLITE_BUSY ){
+        p->pc = (int)(pOp - aOp);
+        p->rc = rc;
+        goto vdbe_return;
+      }
+      goto abort_due_to_error;
+    }
+
+    if( pOp->p2 && p->usesStmtJournal 
+     && (db->autoCommit==0 || db->nVdbeRead>1) 
+    ){
+      assert( sqlite3BtreeIsInTrans(pBt) );
+      if( p->iStatement==0 ){
+        assert( db->nStatement>=0 && db->nSavepoint>=0 );
+        db->nStatement++; 
+        p->iStatement = db->nSavepoint + db->nStatement;
+      }
+
+      rc = sqlite3VtabSavepoint(db, SAVEPOINT_BEGIN, p->iStatement-1);
+      if( rc==SQLITE_OK ){
+        rc = sqlite3BtreeBeginStmt(pBt, p->iStatement);
+      }
+
+      /* Store the current value of the database handles deferred constraint
+      ** counter. If the statement transaction needs to be rolled back,
+      ** the value of this counter needs to be restored too.  */
+      p->nStmtDefCons = db->nDeferredCons;
+      p->nStmtDefImmCons = db->nDeferredImmCons;
+    }
+
+    /* Gather the schema version number for checking:
+    ** IMPLEMENTATION-OF: R-03189-51135 As each SQL statement runs, the schema
+    ** version is checked to ensure that the schema has not changed since the
+    ** SQL statement was prepared.
+    */
+    sqlite3BtreeGetMeta(pBt, BTREE_SCHEMA_VERSION, (u32 *)&iMeta);
+    iGen = db->aDb[pOp->p1].pSchema->iGeneration;
+  }else{
+    iGen = iMeta = 0;
+  }
+  assert( pOp->p5==0 || pOp->p4type==P4_INT32 );
+  if( pOp->p5 && (iMeta!=pOp->p3 || iGen!=pOp->p4.i) ){
+    sqlite3DbFree(db, p->zErrMsg);
+    p->zErrMsg = sqlite3DbStrDup(db, "database schema has changed");
+    /* If the schema-cookie from the database file matches the cookie 
+    ** stored with the in-memory representation of the schema, do
+    ** not reload the schema from the database file.
+    **
+    ** If virtual-tables are in use, this is not just an optimization.
+    ** Often, v-tables store their data in other SQLite tables, which
+    ** are queried from within xNext() and other v-table methods using
+    ** prepared queries. If such a query is out-of-date, we do not want to
+    ** discard the database schema, as the user code implementing the
+    ** v-table would have to be ready for the sqlite3_vtab structure itself
+    ** to be invalidated whenever sqlite3_step() is called from within 
+    ** a v-table method.
+    */
+    if( db->aDb[pOp->p1].pSchema->schema_cookie!=iMeta ){
+      sqlite3ResetOneSchema(db, pOp->p1);
+    }
+    p->expired = 1;
+    rc = SQLITE_SCHEMA;
+  }
+  if( rc ) goto abort_due_to_error;
+  break;
+}
+
+/* Opcode: ReadCookie P1 P2 P3 * *
+**
+** Read cookie number P3 from database P1 and write it into register P2.
+** P3==1 is the schema version.  P3==2 is the database format.
+** P3==3 is the recommended pager cache size, and so forth.  P1==0 is
+** the main database file and P1==1 is the database file used to store
+** temporary tables.
+**
+** There must be a read-lock on the database (either a transaction
+** must be started or there must be an open cursor) before
+** executing this instruction.
+*/
+case OP_ReadCookie: {               /* out2 */
+  int iMeta;
+  int iDb;
+  int iCookie;
+
+  assert( p->bIsReader );
+  iDb = pOp->p1;
+  iCookie = pOp->p3;
+  assert( pOp->p3<SQLITE_N_BTREE_META );
+  assert( iDb>=0 && iDb<db->nDb );
+  assert( db->aDb[iDb].pBt!=0 );
+  assert( DbMaskTest(p->btreeMask, iDb) );
+
+  sqlite3BtreeGetMeta(db->aDb[iDb].pBt, iCookie, (u32 *)&iMeta);
+  pOut = out2Prerelease(p, pOp);
+  pOut->u.i = iMeta;
+  break;
+}
+
+/* Opcode: SetCookie P1 P2 P3 * *
+**
+** Write the integer value P3 into cookie number P2 of database P1.
+** P2==1 is the schema version.  P2==2 is the database format.
+** P2==3 is the recommended pager cache 
+** size, and so forth.  P1==0 is the main database file and P1==1 is the 
+** database file used to store temporary tables.
+**
+** A transaction must be started before executing this opcode.
+*/
+case OP_SetCookie: {
+  Db *pDb;
+  assert( pOp->p2<SQLITE_N_BTREE_META );
+  assert( pOp->p1>=0 && pOp->p1<db->nDb );
+  assert( DbMaskTest(p->btreeMask, pOp->p1) );
+  assert( p->readOnly==0 );
+  pDb = &db->aDb[pOp->p1];
+  assert( pDb->pBt!=0 );
+  assert( sqlite3SchemaMutexHeld(db, pOp->p1, 0) );
+  /* See note about index shifting on OP_ReadCookie */
+  rc = sqlite3BtreeUpdateMeta(pDb->pBt, pOp->p2, pOp->p3);
+  if( pOp->p2==BTREE_SCHEMA_VERSION ){
+    /* When the schema cookie changes, record the new cookie internally */
+    pDb->pSchema->schema_cookie = pOp->p3;
+    db->flags |= SQLITE_InternChanges;
+  }else if( pOp->p2==BTREE_FILE_FORMAT ){
+    /* Record changes in the file format */
+    pDb->pSchema->file_format = pOp->p3;
+  }
+  if( pOp->p1==1 ){
+    /* Invalidate all prepared statements whenever the TEMP database
+    ** schema is changed.  Ticket #1644 */
+    sqlite3ExpirePreparedStatements(db);
+    p->expired = 0;
+  }
+  if( rc ) goto abort_due_to_error;
+  break;
+}
+
+/* Opcode: OpenRead P1 P2 P3 P4 P5
+** Synopsis: root=P2 iDb=P3
+**
+** Open a read-only cursor for the database table whose root page is
+** P2 in a database file.  The database file is determined by P3. 
+** P3==0 means the main database, P3==1 means the database used for 
+** temporary tables, and P3>1 means used the corresponding attached
+** database.  Give the new cursor an identifier of P1.  The P1
+** values need not be contiguous but all P1 values should be small integers.
+** It is an error for P1 to be negative.
+**
+** If P5!=0 then use the content of register P2 as the root page, not
+** the value of P2 itself.
+**
+** There will be a read lock on the database whenever there is an
+** open cursor.  If the database was unlocked prior to this instruction
+** then a read lock is acquired as part of this instruction.  A read
+** lock allows other processes to read the database but prohibits
+** any other process from modifying the database.  The read lock is
+** released when all cursors are closed.  If this instruction attempts
+** to get a read lock but fails, the script terminates with an
+** SQLITE_BUSY error code.
+**
+** The P4 value may be either an integer (P4_INT32) or a pointer to
+** a KeyInfo structure (P4_KEYINFO). If it is a pointer to a KeyInfo 
+** structure, then said structure defines the content and collating 
+** sequence of the index being opened. Otherwise, if P4 is an integer 
+** value, it is set to the number of columns in the table.
+**
+** See also: OpenWrite, ReopenIdx
+*/
+/* Opcode: ReopenIdx P1 P2 P3 P4 P5
+** Synopsis: root=P2 iDb=P3
+**
+** The ReopenIdx opcode works exactly like ReadOpen except that it first
+** checks to see if the cursor on P1 is already open with a root page
+** number of P2 and if it is this opcode becomes a no-op.  In other words,
+** if the cursor is already open, do not reopen it.
+**
+** The ReopenIdx opcode may only be used with P5==0 and with P4 being
+** a P4_KEYINFO object.  Furthermore, the P3 value must be the same as
+** every other ReopenIdx or OpenRead for the same cursor number.
+**
+** See the OpenRead opcode documentation for additional information.
+*/
+/* Opcode: OpenWrite P1 P2 P3 P4 P5
+** Synopsis: root=P2 iDb=P3
+**
+** Open a read/write cursor named P1 on the table or index whose root
+** page is P2.  Or if P5!=0 use the content of register P2 to find the
+** root page.
+**
+** The P4 value may be either an integer (P4_INT32) or a pointer to
+** a KeyInfo structure (P4_KEYINFO). If it is a pointer to a KeyInfo 
+** structure, then said structure defines the content and collating 
+** sequence of the index being opened. Otherwise, if P4 is an integer 
+** value, it is set to the number of columns in the table, or to the
+** largest index of any column of the table that is actually used.
+**
+** This instruction works just like OpenRead except that it opens the cursor
+** in read/write mode.  For a given table, there can be one or more read-only
+** cursors or a single read/write cursor but not both.
+**
+** See also OpenRead.
+*/
+case OP_ReopenIdx: {
+  int nField;
+  KeyInfo *pKeyInfo;
+  int p2;
+  int iDb;
+  int wrFlag;
+  Btree *pX;
+  VdbeCursor *pCur;
+  Db *pDb;
+
+  assert( pOp->p5==0 || pOp->p5==OPFLAG_SEEKEQ );
+  assert( pOp->p4type==P4_KEYINFO );
+  pCur = p->apCsr[pOp->p1];
+  if( pCur && pCur->pgnoRoot==(u32)pOp->p2 ){
+    assert( pCur->iDb==pOp->p3 );      /* Guaranteed by the code generator */
+    goto open_cursor_set_hints;
+  }
+  /* If the cursor is not currently open or is open on a different
+  ** index, then fall through into OP_OpenRead to force a reopen */
+case OP_OpenRead:
+case OP_OpenWrite:
+
+  assert( pOp->opcode==OP_OpenWrite || pOp->p5==0 || pOp->p5==OPFLAG_SEEKEQ );
+  assert( p->bIsReader );
+  assert( pOp->opcode==OP_OpenRead || pOp->opcode==OP_ReopenIdx
+          || p->readOnly==0 );
+
+  if( p->expired ){
+    rc = SQLITE_ABORT_ROLLBACK;
+    goto abort_due_to_error;
+  }
+
+  nField = 0;
+  pKeyInfo = 0;
+  p2 = pOp->p2;
+  iDb = pOp->p3;
+  assert( iDb>=0 && iDb<db->nDb );
+  assert( DbMaskTest(p->btreeMask, iDb) );
+  pDb = &db->aDb[iDb];
+  pX = pDb->pBt;
+  assert( pX!=0 );
+  if( pOp->opcode==OP_OpenWrite ){
+    assert( OPFLAG_FORDELETE==BTREE_FORDELETE );
+    wrFlag = BTREE_WRCSR | (pOp->p5 & OPFLAG_FORDELETE);
+    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+    if( pDb->pSchema->file_format < p->minWriteFileFormat ){
+      p->minWriteFileFormat = pDb->pSchema->file_format;
+    }
+  }else{
+    wrFlag = 0;
+  }
+  if( pOp->p5 & OPFLAG_P2ISREG ){
+    assert( p2>0 );
+    assert( p2<=(p->nMem+1 - p->nCursor) );
+    pIn2 = &aMem[p2];
+    assert( memIsValid(pIn2) );
+    assert( (pIn2->flags & MEM_Int)!=0 );
+    sqlite3VdbeMemIntegerify(pIn2);
+    p2 = (int)pIn2->u.i;
+    /* The p2 value always comes from a prior OP_CreateTable opcode and
+    ** that opcode will always set the p2 value to 2 or more or else fail.
+    ** If there were a failure, the prepared statement would have halted
+    ** before reaching this instruction. */
+    assert( p2>=2 );
+  }
+  if( pOp->p4type==P4_KEYINFO ){
+    pKeyInfo = pOp->p4.pKeyInfo;
+    assert( pKeyInfo->enc==ENC(db) );
+    assert( pKeyInfo->db==db );
+    nField = pKeyInfo->nField+pKeyInfo->nXField;
+  }else if( pOp->p4type==P4_INT32 ){
+    nField = pOp->p4.i;
+  }
+  assert( pOp->p1>=0 );
+  assert( nField>=0 );
+  testcase( nField==0 );  /* Table with INTEGER PRIMARY KEY and nothing else */
+  pCur = allocateCursor(p, pOp->p1, nField, iDb, CURTYPE_BTREE);
+  if( pCur==0 ) goto no_mem;
+  pCur->nullRow = 1;
+  pCur->isOrdered = 1;
+  pCur->pgnoRoot = p2;
+#ifdef SQLITE_DEBUG
+  pCur->wrFlag = wrFlag;
+#endif
+  rc = sqlite3BtreeCursor(pX, p2, wrFlag, pKeyInfo, pCur->uc.pCursor);
+  pCur->pKeyInfo = pKeyInfo;
+  /* Set the VdbeCursor.isTable variable. Previous versions of
+  ** SQLite used to check if the root-page flags were sane at this point
+  ** and report database corruption if they were not, but this check has
+  ** since moved into the btree layer.  */  
+  pCur->isTable = pOp->p4type!=P4_KEYINFO;
+
+open_cursor_set_hints:
+  assert( OPFLAG_BULKCSR==BTREE_BULKLOAD );
+  assert( OPFLAG_SEEKEQ==BTREE_SEEK_EQ );
+  testcase( pOp->p5 & OPFLAG_BULKCSR );
+#ifdef SQLITE_ENABLE_CURSOR_HINTS
+  testcase( pOp->p2 & OPFLAG_SEEKEQ );
+#endif
+  sqlite3BtreeCursorHintFlags(pCur->uc.pCursor,
+                               (pOp->p5 & (OPFLAG_BULKCSR|OPFLAG_SEEKEQ)));
+  if( rc ) goto abort_due_to_error;
+  break;
+}
+
+/* Opcode: OpenEphemeral P1 P2 * P4 P5
+** Synopsis: nColumn=P2
+**
+** Open a new cursor P1 to a transient table.
+** The cursor is always opened read/write even if 
+** the main database is read-only.  The ephemeral
+** table is deleted automatically when the cursor is closed.
+**
+** P2 is the number of columns in the ephemeral table.
+** The cursor points to a BTree table if P4==0 and to a BTree index
+** if P4 is not 0.  If P4 is not NULL, it points to a KeyInfo structure
+** that defines the format of keys in the index.
+**
+** The P5 parameter can be a mask of the BTREE_* flags defined
+** in btree.h.  These flags control aspects of the operation of
+** the btree.  The BTREE_OMIT_JOURNAL and BTREE_SINGLE flags are
+** added automatically.
+*/
+/* Opcode: OpenAutoindex P1 P2 * P4 *
+** Synopsis: nColumn=P2
+**
+** This opcode works the same as OP_OpenEphemeral.  It has a
+** different name to distinguish its use.  Tables created using
+** by this opcode will be used for automatically created transient
+** indices in joins.
+*/
+case OP_OpenAutoindex: 
+case OP_OpenEphemeral: {
+  VdbeCursor *pCx;
+  KeyInfo *pKeyInfo;
+
+  static const int vfsFlags = 
+      SQLITE_OPEN_READWRITE |
+      SQLITE_OPEN_CREATE |
+      SQLITE_OPEN_EXCLUSIVE |
+      SQLITE_OPEN_DELETEONCLOSE |
+      SQLITE_OPEN_TRANSIENT_DB;
+  assert( pOp->p1>=0 );
+  assert( pOp->p2>=0 );
+  pCx = allocateCursor(p, pOp->p1, pOp->p2, -1, CURTYPE_BTREE);
+  if( pCx==0 ) goto no_mem;
+  pCx->nullRow = 1;
+  pCx->isEphemeral = 1;
+  rc = sqlite3BtreeOpen(db->pVfs, 0, db, &pCx->pBt, 
+                        BTREE_OMIT_JOURNAL | BTREE_SINGLE | pOp->p5, vfsFlags);
+  if( rc==SQLITE_OK ){
+    rc = sqlite3BtreeBeginTrans(pCx->pBt, 1);
+  }
+  if( rc==SQLITE_OK ){
+    /* If a transient index is required, create it by calling
+    ** sqlite3BtreeCreateTable() with the BTREE_BLOBKEY flag before
+    ** opening it. If a transient table is required, just use the
+    ** automatically created table with root-page 1 (an BLOB_INTKEY table).
+    */
+    if( (pKeyInfo = pOp->p4.pKeyInfo)!=0 ){
+      int pgno;
+      assert( pOp->p4type==P4_KEYINFO );
+      rc = sqlite3BtreeCreateTable(pCx->pBt, &pgno, BTREE_BLOBKEY | pOp->p5); 
+      if( rc==SQLITE_OK ){
+        assert( pgno==MASTER_ROOT+1 );
+        assert( pKeyInfo->db==db );
+        assert( pKeyInfo->enc==ENC(db) );
+        pCx->pKeyInfo = pKeyInfo;
+        rc = sqlite3BtreeCursor(pCx->pBt, pgno, BTREE_WRCSR,
+                                pKeyInfo, pCx->uc.pCursor);
+      }
+      pCx->isTable = 0;
+    }else{
+      rc = sqlite3BtreeCursor(pCx->pBt, MASTER_ROOT, BTREE_WRCSR,
+                              0, pCx->uc.pCursor);
+      pCx->isTable = 1;
+    }
+  }
+  if( rc ) goto abort_due_to_error;
+  pCx->isOrdered = (pOp->p5!=BTREE_UNORDERED);
+  break;
+}
+
+/* Opcode: SorterOpen P1 P2 P3 P4 *
+**
+** This opcode works like OP_OpenEphemeral except that it opens
+** a transient index that is specifically designed to sort large
+** tables using an external merge-sort algorithm.
+**
+** If argument P3 is non-zero, then it indicates that the sorter may
+** assume that a stable sort considering the first P3 fields of each
+** key is sufficient to produce the required results.
+*/
+case OP_SorterOpen: {
+  VdbeCursor *pCx;
+
+  assert( pOp->p1>=0 );
+  assert( pOp->p2>=0 );
+  pCx = allocateCursor(p, pOp->p1, pOp->p2, -1, CURTYPE_SORTER);
+  if( pCx==0 ) goto no_mem;
+  pCx->pKeyInfo = pOp->p4.pKeyInfo;
+  assert( pCx->pKeyInfo->db==db );
+  assert( pCx->pKeyInfo->enc==ENC(db) );
+  rc = sqlite3VdbeSorterInit(db, pOp->p3, pCx);
+  if( rc ) goto abort_due_to_error;
+  break;
+}
+
+/* Opcode: SequenceTest P1 P2 * * *
+** Synopsis: if( cursor[P1].ctr++ ) pc = P2
+**
+** P1 is a sorter cursor. If the sequence counter is currently zero, jump
+** to P2. Regardless of whether or not the jump is taken, increment the
+** the sequence value.
+*/
+case OP_SequenceTest: {
+  VdbeCursor *pC;
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  pC = p->apCsr[pOp->p1];
+  assert( isSorter(pC) );
+  if( (pC->seqCount++)==0 ){
+    goto jump_to_p2;
+  }
+  break;
+}
+
+/* Opcode: OpenPseudo P1 P2 P3 * *
+** Synopsis: P3 columns in r[P2]
+**
+** Open a new cursor that points to a fake table that contains a single
+** row of data.  The content of that one row is the content of memory
+** register P2.  In other words, cursor P1 becomes an alias for the 
+** MEM_Blob content contained in register P2.
+**
+** A pseudo-table created by this opcode is used to hold a single
+** row output from the sorter so that the row can be decomposed into
+** individual columns using the OP_Column opcode.  The OP_Column opcode
+** is the only cursor opcode that works with a pseudo-table.
+**
+** P3 is the number of fields in the records that will be stored by
+** the pseudo-table.
+*/
+case OP_OpenPseudo: {
+  VdbeCursor *pCx;
+
+  assert( pOp->p1>=0 );
+  assert( pOp->p3>=0 );
+  pCx = allocateCursor(p, pOp->p1, pOp->p3, -1, CURTYPE_PSEUDO);
+  if( pCx==0 ) goto no_mem;
+  pCx->nullRow = 1;
+  pCx->uc.pseudoTableReg = pOp->p2;
+  pCx->isTable = 1;
+  assert( pOp->p5==0 );
+  break;
+}
+
+/* Opcode: Close P1 * * * *
+**
+** Close a cursor previously opened as P1.  If P1 is not
+** currently open, this instruction is a no-op.
+*/
+case OP_Close: {
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  sqlite3VdbeFreeCursor(p, p->apCsr[pOp->p1]);
+  p->apCsr[pOp->p1] = 0;
+  break;
+}
+
+#ifdef SQLITE_ENABLE_COLUMN_USED_MASK
+/* Opcode: ColumnsUsed P1 * * P4 *
+**
+** This opcode (which only exists if SQLite was compiled with
+** SQLITE_ENABLE_COLUMN_USED_MASK) identifies which columns of the
+** table or index for cursor P1 are used.  P4 is a 64-bit integer
+** (P4_INT64) in which the first 63 bits are one for each of the
+** first 63 columns of the table or index that are actually used
+** by the cursor.  The high-order bit is set if any column after
+** the 64th is used.
+*/
+case OP_ColumnsUsed: {
+  VdbeCursor *pC;
+  pC = p->apCsr[pOp->p1];
+  assert( pC->eCurType==CURTYPE_BTREE );
+  pC->maskUsed = *(u64*)pOp->p4.pI64;
+  break;
+}
+#endif
+
+/* Opcode: SeekGE P1 P2 P3 P4 *
+** Synopsis: key=r[P3@P4]
+**
+** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
+** use the value in register P3 as the key.  If cursor P1 refers 
+** to an SQL index, then P3 is the first in an array of P4 registers 
+** that are used as an unpacked index key. 
+**
+** Reposition cursor P1 so that  it points to the smallest entry that 
+** is greater than or equal to the key value. If there are no records 
+** greater than or equal to the key and P2 is not zero, then jump to P2.
+**
+** If the cursor P1 was opened using the OPFLAG_SEEKEQ flag, then this
+** opcode will always land on a record that equally equals the key, or
+** else jump immediately to P2.  When the cursor is OPFLAG_SEEKEQ, this
+** opcode must be followed by an IdxLE opcode with the same arguments.
+** The IdxLE opcode will be skipped if this opcode succeeds, but the
+** IdxLE opcode will be used on subsequent loop iterations.
+**
+** This opcode leaves the cursor configured to move in forward order,
+** from the beginning toward the end.  In other words, the cursor is
+** configured to use Next, not Prev.
+**
+** See also: Found, NotFound, SeekLt, SeekGt, SeekLe
+*/
+/* Opcode: SeekGT P1 P2 P3 P4 *
+** Synopsis: key=r[P3@P4]
+**
+** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
+** use the value in register P3 as a key. If cursor P1 refers 
+** to an SQL index, then P3 is the first in an array of P4 registers 
+** that are used as an unpacked index key. 
+**
+** Reposition cursor P1 so that  it points to the smallest entry that 
+** is greater than the key value. If there are no records greater than 
+** the key and P2 is not zero, then jump to P2.
+**
+** This opcode leaves the cursor configured to move in forward order,
+** from the beginning toward the end.  In other words, the cursor is
+** configured to use Next, not Prev.
+**
+** See also: Found, NotFound, SeekLt, SeekGe, SeekLe
+*/
+/* Opcode: SeekLT P1 P2 P3 P4 * 
+** Synopsis: key=r[P3@P4]
+**
+** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
+** use the value in register P3 as a key. If cursor P1 refers 
+** to an SQL index, then P3 is the first in an array of P4 registers 
+** that are used as an unpacked index key. 
+**
+** Reposition cursor P1 so that  it points to the largest entry that 
+** is less than the key value. If there are no records less than 
+** the key and P2 is not zero, then jump to P2.
+**
+** This opcode leaves the cursor configured to move in reverse order,
+** from the end toward the beginning.  In other words, the cursor is
+** configured to use Prev, not Next.
+**
+** See also: Found, NotFound, SeekGt, SeekGe, SeekLe
+*/
+/* Opcode: SeekLE P1 P2 P3 P4 *
+** Synopsis: key=r[P3@P4]
+**
+** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
+** use the value in register P3 as a key. If cursor P1 refers 
+** to an SQL index, then P3 is the first in an array of P4 registers 
+** that are used as an unpacked index key. 
+**
+** Reposition cursor P1 so that it points to the largest entry that 
+** is less than or equal to the key value. If there are no records 
+** less than or equal to the key and P2 is not zero, then jump to P2.
+**
+** This opcode leaves the cursor configured to move in reverse order,
+** from the end toward the beginning.  In other words, the cursor is
+** configured to use Prev, not Next.
+**
+** If the cursor P1 was opened using the OPFLAG_SEEKEQ flag, then this
+** opcode will always land on a record that equally equals the key, or
+** else jump immediately to P2.  When the cursor is OPFLAG_SEEKEQ, this
+** opcode must be followed by an IdxGE opcode with the same arguments.
+** The IdxGE opcode will be skipped if this opcode succeeds, but the
+** IdxGE opcode will be used on subsequent loop iterations.
+**
+** See also: Found, NotFound, SeekGt, SeekGe, SeekLt
+*/
+case OP_SeekLT:         /* jump, in3 */
+case OP_SeekLE:         /* jump, in3 */
+case OP_SeekGE:         /* jump, in3 */
+case OP_SeekGT: {       /* jump, in3 */
+  int res;           /* Comparison result */
+  int oc;            /* Opcode */
+  VdbeCursor *pC;    /* The cursor to seek */
+  UnpackedRecord r;  /* The key to seek for */
+  int nField;        /* Number of columns or fields in the key */
+  i64 iKey;          /* The rowid we are to seek to */
+  int eqOnly;        /* Only interested in == results */
+
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  assert( pOp->p2!=0 );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+  assert( pC->eCurType==CURTYPE_BTREE );
+  assert( OP_SeekLE == OP_SeekLT+1 );
+  assert( OP_SeekGE == OP_SeekLT+2 );
+  assert( OP_SeekGT == OP_SeekLT+3 );
+  assert( pC->isOrdered );
+  assert( pC->uc.pCursor!=0 );
+  oc = pOp->opcode;
+  eqOnly = 0;
+  pC->nullRow = 0;
+#ifdef SQLITE_DEBUG
+  pC->seekOp = pOp->opcode;
+#endif
+
+  if( pC->isTable ){
+    /* The BTREE_SEEK_EQ flag is only set on index cursors */
+    assert( sqlite3BtreeCursorHasHint(pC->uc.pCursor, BTREE_SEEK_EQ)==0 );
+
+    /* The input value in P3 might be of any type: integer, real, string,
+    ** blob, or NULL.  But it needs to be an integer before we can do
+    ** the seek, so convert it. */
+    pIn3 = &aMem[pOp->p3];
+    if( (pIn3->flags & (MEM_Int|MEM_Real|MEM_Str))==MEM_Str ){
+      applyNumericAffinity(pIn3, 0);
+    }
+    iKey = sqlite3VdbeIntValue(pIn3);
+
+    /* If the P3 value could not be converted into an integer without
+    ** loss of information, then special processing is required... */
+    if( (pIn3->flags & MEM_Int)==0 ){
+      if( (pIn3->flags & MEM_Real)==0 ){
+        /* If the P3 value cannot be converted into any kind of a number,
+        ** then the seek is not possible, so jump to P2 */
+        VdbeBranchTaken(1,2); goto jump_to_p2;
+        break;
+      }
+
+      /* If the approximation iKey is larger than the actual real search
+      ** term, substitute >= for > and < for <=. e.g. if the search term
+      ** is 4.9 and the integer approximation 5:
+      **
+      **        (x >  4.9)    ->     (x >= 5)
+      **        (x <= 4.9)    ->     (x <  5)
+      */
+      if( pIn3->u.r<(double)iKey ){
+        assert( OP_SeekGE==(OP_SeekGT-1) );
+        assert( OP_SeekLT==(OP_SeekLE-1) );
+        assert( (OP_SeekLE & 0x0001)==(OP_SeekGT & 0x0001) );
+        if( (oc & 0x0001)==(OP_SeekGT & 0x0001) ) oc--;
+      }
+
+      /* If the approximation iKey is smaller than the actual real search
+      ** term, substitute <= for < and > for >=.  */
+      else if( pIn3->u.r>(double)iKey ){
+        assert( OP_SeekLE==(OP_SeekLT+1) );
+        assert( OP_SeekGT==(OP_SeekGE+1) );
+        assert( (OP_SeekLT & 0x0001)==(OP_SeekGE & 0x0001) );
+        if( (oc & 0x0001)==(OP_SeekLT & 0x0001) ) oc++;
+      }
+    } 
+    rc = sqlite3BtreeMovetoUnpacked(pC->uc.pCursor, 0, (u64)iKey, 0, &res);
+    pC->movetoTarget = iKey;  /* Used by OP_Delete */
+    if( rc!=SQLITE_OK ){
+      goto abort_due_to_error;
+    }
+  }else{
+    /* For a cursor with the BTREE_SEEK_EQ hint, only the OP_SeekGE and
+    ** OP_SeekLE opcodes are allowed, and these must be immediately followed
+    ** by an OP_IdxGT or OP_IdxLT opcode, respectively, with the same key.
+    */
+    if( sqlite3BtreeCursorHasHint(pC->uc.pCursor, BTREE_SEEK_EQ) ){
+      eqOnly = 1;
+      assert( pOp->opcode==OP_SeekGE || pOp->opcode==OP_SeekLE );
+      assert( pOp[1].opcode==OP_IdxLT || pOp[1].opcode==OP_IdxGT );
+      assert( pOp[1].p1==pOp[0].p1 );
+      assert( pOp[1].p2==pOp[0].p2 );
+      assert( pOp[1].p3==pOp[0].p3 );
+      assert( pOp[1].p4.i==pOp[0].p4.i );
+    }
+
+    nField = pOp->p4.i;
+    assert( pOp->p4type==P4_INT32 );
+    assert( nField>0 );
+    r.pKeyInfo = pC->pKeyInfo;
+    r.nField = (u16)nField;
+
+    /* The next line of code computes as follows, only faster:
+    **   if( oc==OP_SeekGT || oc==OP_SeekLE ){
+    **     r.default_rc = -1;
+    **   }else{
+    **     r.default_rc = +1;
+    **   }
+    */
+    r.default_rc = ((1 & (oc - OP_SeekLT)) ? -1 : +1);
+    assert( oc!=OP_SeekGT || r.default_rc==-1 );
+    assert( oc!=OP_SeekLE || r.default_rc==-1 );
+    assert( oc!=OP_SeekGE || r.default_rc==+1 );
+    assert( oc!=OP_SeekLT || r.default_rc==+1 );
+
+    r.aMem = &aMem[pOp->p3];
+#ifdef SQLITE_DEBUG
+    { int i; for(i=0; i<r.nField; i++) assert( memIsValid(&r.aMem[i]) ); }
+#endif
+    r.eqSeen = 0;
+    rc = sqlite3BtreeMovetoUnpacked(pC->uc.pCursor, &r, 0, 0, &res);
+    if( rc!=SQLITE_OK ){
+      goto abort_due_to_error;
+    }
+    if( eqOnly && r.eqSeen==0 ){
+      assert( res!=0 );
+      goto seek_not_found;
+    }
+  }
+  pC->deferredMoveto = 0;
+  pC->cacheStatus = CACHE_STALE;
+#ifdef SQLITE_TEST
+  sqlite3_search_count++;
+#endif
+  if( oc>=OP_SeekGE ){  assert( oc==OP_SeekGE || oc==OP_SeekGT );
+    if( res<0 || (res==0 && oc==OP_SeekGT) ){
+      res = 0;
+      rc = sqlite3BtreeNext(pC->uc.pCursor, &res);
+      if( rc!=SQLITE_OK ) goto abort_due_to_error;
+    }else{
+      res = 0;
+    }
+  }else{
+    assert( oc==OP_SeekLT || oc==OP_SeekLE );
+    if( res>0 || (res==0 && oc==OP_SeekLT) ){
+      res = 0;
+      rc = sqlite3BtreePrevious(pC->uc.pCursor, &res);
+      if( rc!=SQLITE_OK ) goto abort_due_to_error;
+    }else{
+      /* res might be negative because the table is empty.  Check to
+      ** see if this is the case.
+      */
+      res = sqlite3BtreeEof(pC->uc.pCursor);
+    }
+  }
+seek_not_found:
+  assert( pOp->p2>0 );
+  VdbeBranchTaken(res!=0,2);
+  if( res ){
+    goto jump_to_p2;
+  }else if( eqOnly ){
+    assert( pOp[1].opcode==OP_IdxLT || pOp[1].opcode==OP_IdxGT );
+    pOp++; /* Skip the OP_IdxLt or OP_IdxGT that follows */
+  }
+  break;
+}
+
+/* Opcode: Found P1 P2 P3 P4 *
+** Synopsis: key=r[P3@P4]
+**
+** If P4==0 then register P3 holds a blob constructed by MakeRecord.  If
+** P4>0 then register P3 is the first of P4 registers that form an unpacked
+** record.
+**
+** Cursor P1 is on an index btree.  If the record identified by P3 and P4
+** is a prefix of any entry in P1 then a jump is made to P2 and
+** P1 is left pointing at the matching entry.
+**
+** This operation leaves the cursor in a state where it can be
+** advanced in the forward direction.  The Next instruction will work,
+** but not the Prev instruction.
+**
+** See also: NotFound, NoConflict, NotExists. SeekGe
+*/
+/* Opcode: NotFound P1 P2 P3 P4 *
+** Synopsis: key=r[P3@P4]
+**
+** If P4==0 then register P3 holds a blob constructed by MakeRecord.  If
+** P4>0 then register P3 is the first of P4 registers that form an unpacked
+** record.
+** 
+** Cursor P1 is on an index btree.  If the record identified by P3 and P4
+** is not the prefix of any entry in P1 then a jump is made to P2.  If P1 
+** does contain an entry whose prefix matches the P3/P4 record then control
+** falls through to the next instruction and P1 is left pointing at the
+** matching entry.
+**
+** This operation leaves the cursor in a state where it cannot be
+** advanced in either direction.  In other words, the Next and Prev
+** opcodes do not work after this operation.
+**
+** See also: Found, NotExists, NoConflict
+*/
+/* Opcode: NoConflict P1 P2 P3 P4 *
+** Synopsis: key=r[P3@P4]
+**
+** If P4==0 then register P3 holds a blob constructed by MakeRecord.  If
+** P4>0 then register P3 is the first of P4 registers that form an unpacked
+** record.
+** 
+** Cursor P1 is on an index btree.  If the record identified by P3 and P4
+** contains any NULL value, jump immediately to P2.  If all terms of the
+** record are not-NULL then a check is done to determine if any row in the
+** P1 index btree has a matching key prefix.  If there are no matches, jump
+** immediately to P2.  If there is a match, fall through and leave the P1
+** cursor pointing to the matching row.
+**
+** This opcode is similar to OP_NotFound with the exceptions that the
+** branch is always taken if any part of the search key input is NULL.
+**
+** This operation leaves the cursor in a state where it cannot be
+** advanced in either direction.  In other words, the Next and Prev
+** opcodes do not work after this operation.
+**
+** See also: NotFound, Found, NotExists
+*/
+case OP_NoConflict:     /* jump, in3 */
+case OP_NotFound:       /* jump, in3 */
+case OP_Found: {        /* jump, in3 */
+  int alreadyExists;
+  int takeJump;
+  int ii;
+  VdbeCursor *pC;
+  int res;
+  char *pFree;
+  UnpackedRecord *pIdxKey;
+  UnpackedRecord r;
+  char aTempRec[ROUND8(sizeof(UnpackedRecord)) + sizeof(Mem)*4 + 7];
+
+#ifdef SQLITE_TEST
+  if( pOp->opcode!=OP_NoConflict ) sqlite3_found_count++;
+#endif
+
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  assert( pOp->p4type==P4_INT32 );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+#ifdef SQLITE_DEBUG
+  pC->seekOp = pOp->opcode;
+#endif
+  pIn3 = &aMem[pOp->p3];
+  assert( pC->eCurType==CURTYPE_BTREE );
+  assert( pC->uc.pCursor!=0 );
+  assert( pC->isTable==0 );
+  pFree = 0;
+  if( pOp->p4.i>0 ){
+    r.pKeyInfo = pC->pKeyInfo;
+    r.nField = (u16)pOp->p4.i;
+    r.aMem = pIn3;
+#ifdef SQLITE_DEBUG
+    for(ii=0; ii<r.nField; ii++){
+      assert( memIsValid(&r.aMem[ii]) );
+      assert( (r.aMem[ii].flags & MEM_Zero)==0 || r.aMem[ii].n==0 );
+      if( ii ) REGISTER_TRACE(pOp->p3+ii, &r.aMem[ii]);
+    }
+#endif
+    pIdxKey = &r;
+  }else{
+    pIdxKey = sqlite3VdbeAllocUnpackedRecord(
+        pC->pKeyInfo, aTempRec, sizeof(aTempRec), &pFree
+    );
+    if( pIdxKey==0 ) goto no_mem;
+    assert( pIn3->flags & MEM_Blob );
+    (void)ExpandBlob(pIn3);
+    sqlite3VdbeRecordUnpack(pC->pKeyInfo, pIn3->n, pIn3->z, pIdxKey);
+  }
+  pIdxKey->default_rc = 0;
+  takeJump = 0;
+  if( pOp->opcode==OP_NoConflict ){
+    /* For the OP_NoConflict opcode, take the jump if any of the
+    ** input fields are NULL, since any key with a NULL will not
+    ** conflict */
+    for(ii=0; ii<pIdxKey->nField; ii++){
+      if( pIdxKey->aMem[ii].flags & MEM_Null ){
+        takeJump = 1;
+        break;
+      }
+    }
+  }
+  rc = sqlite3BtreeMovetoUnpacked(pC->uc.pCursor, pIdxKey, 0, 0, &res);
+  sqlite3DbFree(db, pFree);
+  if( rc!=SQLITE_OK ){
+    goto abort_due_to_error;
+  }
+  pC->seekResult = res;
+  alreadyExists = (res==0);
+  pC->nullRow = 1-alreadyExists;
+  pC->deferredMoveto = 0;
+  pC->cacheStatus = CACHE_STALE;
+  if( pOp->opcode==OP_Found ){
+    VdbeBranchTaken(alreadyExists!=0,2);
+    if( alreadyExists ) goto jump_to_p2;
+  }else{
+    VdbeBranchTaken(takeJump||alreadyExists==0,2);
+    if( takeJump || !alreadyExists ) goto jump_to_p2;
+  }
+  break;
+}
+
+/* Opcode: SeekRowid P1 P2 P3 * *
+** Synopsis: intkey=r[P3]
+**
+** P1 is the index of a cursor open on an SQL table btree (with integer
+** keys).  If register P3 does not contain an integer or if P1 does not
+** contain a record with rowid P3 then jump immediately to P2.  
+** Or, if P2 is 0, raise an SQLITE_CORRUPT error. If P1 does contain
+** a record with rowid P3 then 
+** leave the cursor pointing at that record and fall through to the next
+** instruction.
+**
+** The OP_NotExists opcode performs the same operation, but with OP_NotExists
+** the P3 register must be guaranteed to contain an integer value.  With this
+** opcode, register P3 might not contain an integer.
+**
+** The OP_NotFound opcode performs the same operation on index btrees
+** (with arbitrary multi-value keys).
+**
+** This opcode leaves the cursor in a state where it cannot be advanced
+** in either direction.  In other words, the Next and Prev opcodes will
+** not work following this opcode.
+**
+** See also: Found, NotFound, NoConflict, SeekRowid
+*/
+/* Opcode: NotExists P1 P2 P3 * *
+** Synopsis: intkey=r[P3]
+**
+** P1 is the index of a cursor open on an SQL table btree (with integer
+** keys).  P3 is an integer rowid.  If P1 does not contain a record with
+** rowid P3 then jump immediately to P2.  Or, if P2 is 0, raise an
+** SQLITE_CORRUPT error. If P1 does contain a record with rowid P3 then 
+** leave the cursor pointing at that record and fall through to the next
+** instruction.
+**
+** The OP_SeekRowid opcode performs the same operation but also allows the
+** P3 register to contain a non-integer value, in which case the jump is
+** always taken.  This opcode requires that P3 always contain an integer.
+**
+** The OP_NotFound opcode performs the same operation on index btrees
+** (with arbitrary multi-value keys).
+**
+** This opcode leaves the cursor in a state where it cannot be advanced
+** in either direction.  In other words, the Next and Prev opcodes will
+** not work following this opcode.
+**
+** See also: Found, NotFound, NoConflict, SeekRowid
+*/
+case OP_SeekRowid: {        /* jump, in3 */
+  VdbeCursor *pC;
+  BtCursor *pCrsr;
+  int res;
+  u64 iKey;
+
+  pIn3 = &aMem[pOp->p3];
+  if( (pIn3->flags & MEM_Int)==0 ){
+    applyAffinity(pIn3, SQLITE_AFF_NUMERIC, encoding);
+    if( (pIn3->flags & MEM_Int)==0 ) goto jump_to_p2;
+  }
+  /* Fall through into OP_NotExists */
+case OP_NotExists:          /* jump, in3 */
+  pIn3 = &aMem[pOp->p3];
+  assert( pIn3->flags & MEM_Int );
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+#ifdef SQLITE_DEBUG
+  pC->seekOp = 0;
+#endif
+  assert( pC->isTable );
+  assert( pC->eCurType==CURTYPE_BTREE );
+  pCrsr = pC->uc.pCursor;
+  assert( pCrsr!=0 );
+  res = 0;
+  iKey = pIn3->u.i;
+  rc = sqlite3BtreeMovetoUnpacked(pCrsr, 0, iKey, 0, &res);
+  assert( rc==SQLITE_OK || res==0 );
+  pC->movetoTarget = iKey;  /* Used by OP_Delete */
+  pC->nullRow = 0;
+  pC->cacheStatus = CACHE_STALE;
+  pC->deferredMoveto = 0;
+  VdbeBranchTaken(res!=0,2);
+  pC->seekResult = res;
+  if( res!=0 ){
+    assert( rc==SQLITE_OK );
+    if( pOp->p2==0 ){
+      rc = SQLITE_CORRUPT_BKPT;
+    }else{
+      goto jump_to_p2;
+    }
+  }
+  if( rc ) goto abort_due_to_error;
+  break;
+}
+
+/* Opcode: Sequence P1 P2 * * *
+** Synopsis: r[P2]=cursor[P1].ctr++
+**
+** Find the next available sequence number for cursor P1.
+** Write the sequence number into register P2.
+** The sequence number on the cursor is incremented after this
+** instruction.  
+*/
+case OP_Sequence: {           /* out2 */
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  assert( p->apCsr[pOp->p1]!=0 );
+  assert( p->apCsr[pOp->p1]->eCurType!=CURTYPE_VTAB );
+  pOut = out2Prerelease(p, pOp);
+  pOut->u.i = p->apCsr[pOp->p1]->seqCount++;
+  break;
+}
+
+
+/* Opcode: NewRowid P1 P2 P3 * *
+** Synopsis: r[P2]=rowid
+**
+** Get a new integer record number (a.k.a "rowid") used as the key to a table.
+** The record number is not previously used as a key in the database
+** table that cursor P1 points to.  The new record number is written
+** written to register P2.
+**
+** If P3>0 then P3 is a register in the root frame of this VDBE that holds 
+** the largest previously generated record number. No new record numbers are
+** allowed to be less than this value. When this value reaches its maximum, 
+** an SQLITE_FULL error is generated. The P3 register is updated with the '
+** generated record number. This P3 mechanism is used to help implement the
+** AUTOINCREMENT feature.
+*/
+case OP_NewRowid: {           /* out2 */
+  i64 v;                 /* The new rowid */
+  VdbeCursor *pC;        /* Cursor of table to get the new rowid */
+  int res;               /* Result of an sqlite3BtreeLast() */
+  int cnt;               /* Counter to limit the number of searches */
+  Mem *pMem;             /* Register holding largest rowid for AUTOINCREMENT */
+  VdbeFrame *pFrame;     /* Root frame of VDBE */
+
+  v = 0;
+  res = 0;
+  pOut = out2Prerelease(p, pOp);
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+  assert( pC->eCurType==CURTYPE_BTREE );
+  assert( pC->uc.pCursor!=0 );
+  {
+    /* The next rowid or record number (different terms for the same
+    ** thing) is obtained in a two-step algorithm.
+    **
+    ** First we attempt to find the largest existing rowid and add one
+    ** to that.  But if the largest existing rowid is already the maximum
+    ** positive integer, we have to fall through to the second
+    ** probabilistic algorithm
+    **
+    ** The second algorithm is to select a rowid at random and see if
+    ** it already exists in the table.  If it does not exist, we have
+    ** succeeded.  If the random rowid does exist, we select a new one
+    ** and try again, up to 100 times.
+    */
+    assert( pC->isTable );
+
+#ifdef SQLITE_32BIT_ROWID
+#   define MAX_ROWID 0x7fffffff
+#else
+    /* Some compilers complain about constants of the form 0x7fffffffffffffff.
+    ** Others complain about 0x7ffffffffffffffffLL.  The following macro seems
+    ** to provide the constant while making all compilers happy.
+    */
+#   define MAX_ROWID  (i64)( (((u64)0x7fffffff)<<32) | (u64)0xffffffff )
+#endif
+
+    if( !pC->useRandomRowid ){
+      rc = sqlite3BtreeLast(pC->uc.pCursor, &res);
+      if( rc!=SQLITE_OK ){
+        goto abort_due_to_error;
+      }
+      if( res ){
+        v = 1;   /* IMP: R-61914-48074 */
+      }else{
+        assert( sqlite3BtreeCursorIsValid(pC->uc.pCursor) );
+        v = sqlite3BtreeIntegerKey(pC->uc.pCursor);
+        if( v>=MAX_ROWID ){
+          pC->useRandomRowid = 1;
+        }else{
+          v++;   /* IMP: R-29538-34987 */
+        }
+      }
+    }
+
+#ifndef SQLITE_OMIT_AUTOINCREMENT
+    if( pOp->p3 ){
+      /* Assert that P3 is a valid memory cell. */
+      assert( pOp->p3>0 );
+      if( p->pFrame ){
+        for(pFrame=p->pFrame; pFrame->pParent; pFrame=pFrame->pParent);
+        /* Assert that P3 is a valid memory cell. */
+        assert( pOp->p3<=pFrame->nMem );
+        pMem = &pFrame->aMem[pOp->p3];
+      }else{
+        /* Assert that P3 is a valid memory cell. */
+        assert( pOp->p3<=(p->nMem+1 - p->nCursor) );
+        pMem = &aMem[pOp->p3];
+        memAboutToChange(p, pMem);
+      }
+      assert( memIsValid(pMem) );
+
+      REGISTER_TRACE(pOp->p3, pMem);
+      sqlite3VdbeMemIntegerify(pMem);
+      assert( (pMem->flags & MEM_Int)!=0 );  /* mem(P3) holds an integer */
+      if( pMem->u.i==MAX_ROWID || pC->useRandomRowid ){
+        rc = SQLITE_FULL;   /* IMP: R-12275-61338 */
+        goto abort_due_to_error;
+      }
+      if( v<pMem->u.i+1 ){
+        v = pMem->u.i + 1;
+      }
+      pMem->u.i = v;
+    }
+#endif
+    if( pC->useRandomRowid ){
+      /* IMPLEMENTATION-OF: R-07677-41881 If the largest ROWID is equal to the
+      ** largest possible integer (9223372036854775807) then the database
+      ** engine starts picking positive candidate ROWIDs at random until
+      ** it finds one that is not previously used. */
+      assert( pOp->p3==0 );  /* We cannot be in random rowid mode if this is
+                             ** an AUTOINCREMENT table. */
+      cnt = 0;
+      do{
+        sqlite3_randomness(sizeof(v), &v);
+        v &= (MAX_ROWID>>1); v++;  /* Ensure that v is greater than zero */
+      }while(  ((rc = sqlite3BtreeMovetoUnpacked(pC->uc.pCursor, 0, (u64)v,
+                                                 0, &res))==SQLITE_OK)
+            && (res==0)
+            && (++cnt<100));
+      if( rc ) goto abort_due_to_error;
+      if( res==0 ){
+        rc = SQLITE_FULL;   /* IMP: R-38219-53002 */
+        goto abort_due_to_error;
+      }
+      assert( v>0 );  /* EV: R-40812-03570 */
+    }
+    pC->deferredMoveto = 0;
+    pC->cacheStatus = CACHE_STALE;
+  }
+  pOut->u.i = v;
+  break;
+}
+
+/* Opcode: Insert P1 P2 P3 P4 P5
+** Synopsis: intkey=r[P3] data=r[P2]
+**
+** Write an entry into the table of cursor P1.  A new entry is
+** created if it doesn't already exist or the data for an existing
+** entry is overwritten.  The data is the value MEM_Blob stored in register
+** number P2. The key is stored in register P3. The key must
+** be a MEM_Int.
+**
+** If the OPFLAG_NCHANGE flag of P5 is set, then the row change count is
+** incremented (otherwise not).  If the OPFLAG_LASTROWID flag of P5 is set,
+** then rowid is stored for subsequent return by the
+** sqlite3_last_insert_rowid() function (otherwise it is unmodified).
+**
+** If the OPFLAG_USESEEKRESULT flag of P5 is set and if the result of
+** the last seek operation (OP_NotExists or OP_SeekRowid) was a success,
+** then this
+** operation will not attempt to find the appropriate row before doing
+** the insert but will instead overwrite the row that the cursor is
+** currently pointing to.  Presumably, the prior OP_NotExists or
+** OP_SeekRowid opcode
+** has already positioned the cursor correctly.  This is an optimization
+** that boosts performance by avoiding redundant seeks.
+**
+** If the OPFLAG_ISUPDATE flag is set, then this opcode is part of an
+** UPDATE operation.  Otherwise (if the flag is clear) then this opcode
+** is part of an INSERT operation.  The difference is only important to
+** the update hook.
+**
+** Parameter P4 may point to a Table structure, or may be NULL. If it is 
+** not NULL, then the update-hook (sqlite3.xUpdateCallback) is invoked 
+** following a successful insert.
+**
+** (WARNING/TODO: If P1 is a pseudo-cursor and P2 is dynamically
+** allocated, then ownership of P2 is transferred to the pseudo-cursor
+** and register P2 becomes ephemeral.  If the cursor is changed, the
+** value of register P2 will then change.  Make sure this does not
+** cause any problems.)
+**
+** This instruction only works on tables.  The equivalent instruction
+** for indices is OP_IdxInsert.
+*/
+/* Opcode: InsertInt P1 P2 P3 P4 P5
+** Synopsis: intkey=P3 data=r[P2]
+**
+** This works exactly like OP_Insert except that the key is the
+** integer value P3, not the value of the integer stored in register P3.
+*/
+case OP_Insert: 
+case OP_InsertInt: {
+  Mem *pData;       /* MEM cell holding data for the record to be inserted */
+  Mem *pKey;        /* MEM cell holding key  for the record */
+  VdbeCursor *pC;   /* Cursor to table into which insert is written */
+  int seekResult;   /* Result of prior seek or 0 if no USESEEKRESULT flag */
+  const char *zDb;  /* database name - used by the update hook */
+  Table *pTab;      /* Table structure - used by update and pre-update hooks */
+  int op;           /* Opcode for update hook: SQLITE_UPDATE or SQLITE_INSERT */
+  BtreePayload x;   /* Payload to be inserted */
+
+  op = 0;
+  pData = &aMem[pOp->p2];
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  assert( memIsValid(pData) );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+  assert( pC->eCurType==CURTYPE_BTREE );
+  assert( pC->uc.pCursor!=0 );
+  assert( pC->isTable );
+  assert( pOp->p4type==P4_TABLE || pOp->p4type>=P4_STATIC );
+  REGISTER_TRACE(pOp->p2, pData);
+
+  if( pOp->opcode==OP_Insert ){
+    pKey = &aMem[pOp->p3];
+    assert( pKey->flags & MEM_Int );
+    assert( memIsValid(pKey) );
+    REGISTER_TRACE(pOp->p3, pKey);
+    x.nKey = pKey->u.i;
+  }else{
+    assert( pOp->opcode==OP_InsertInt );
+    x.nKey = pOp->p3;
+  }
+
+  if( pOp->p4type==P4_TABLE && HAS_UPDATE_HOOK(db) ){
+    assert( pC->isTable );
+    assert( pC->iDb>=0 );
+    zDb = db->aDb[pC->iDb].zDbSName;
+    pTab = pOp->p4.pTab;
+    assert( HasRowid(pTab) );
+    op = ((pOp->p5 & OPFLAG_ISUPDATE) ? SQLITE_UPDATE : SQLITE_INSERT);
+  }else{
+    pTab = 0; /* Not needed.  Silence a comiler warning. */
+    zDb = 0;  /* Not needed.  Silence a compiler warning. */
+  }
+
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+  /* Invoke the pre-update hook, if any */
+  if( db->xPreUpdateCallback 
+   && pOp->p4type==P4_TABLE
+   && !(pOp->p5 & OPFLAG_ISUPDATE)
+  ){
+    sqlite3VdbePreUpdateHook(p, pC, SQLITE_INSERT, zDb, pTab, x.nKey, pOp->p2);
+  }
+#endif
+
+  if( pOp->p5 & OPFLAG_NCHANGE ) p->nChange++;
+  if( pOp->p5 & OPFLAG_LASTROWID ) db->lastRowid = lastRowid = x.nKey;
+  if( pData->flags & MEM_Null ){
+    x.pData = 0;
+    x.nData = 0;
+  }else{
+    assert( pData->flags & (MEM_Blob|MEM_Str) );
+    x.pData = pData->z;
+    x.nData = pData->n;
+  }
+  seekResult = ((pOp->p5 & OPFLAG_USESEEKRESULT) ? pC->seekResult : 0);
+  if( pData->flags & MEM_Zero ){
+    x.nZero = pData->u.nZero;
+  }else{
+    x.nZero = 0;
+  }
+  x.pKey = 0;
+  rc = sqlite3BtreeInsert(pC->uc.pCursor, &x,
+                          (pOp->p5 & OPFLAG_APPEND)!=0, seekResult
+  );
+  pC->deferredMoveto = 0;
+  pC->cacheStatus = CACHE_STALE;
+
+  /* Invoke the update-hook if required. */
+  if( rc ) goto abort_due_to_error;
+  if( db->xUpdateCallback && op ){
+    db->xUpdateCallback(db->pUpdateArg, op, zDb, pTab->zName, x.nKey);
+  }
+  break;
+}
+
+/* Opcode: Delete P1 P2 P3 P4 P5
+**
+** Delete the record at which the P1 cursor is currently pointing.
+**
+** If the OPFLAG_SAVEPOSITION bit of the P5 parameter is set, then
+** the cursor will be left pointing at  either the next or the previous
+** record in the table. If it is left pointing at the next record, then
+** the next Next instruction will be a no-op. As a result, in this case
+** it is ok to delete a record from within a Next loop. If 
+** OPFLAG_SAVEPOSITION bit of P5 is clear, then the cursor will be
+** left in an undefined state.
+**
+** If the OPFLAG_AUXDELETE bit is set on P5, that indicates that this
+** delete one of several associated with deleting a table row and all its
+** associated index entries.  Exactly one of those deletes is the "primary"
+** delete.  The others are all on OPFLAG_FORDELETE cursors or else are
+** marked with the AUXDELETE flag.
+**
+** If the OPFLAG_NCHANGE flag of P2 (NB: P2 not P5) is set, then the row
+** change count is incremented (otherwise not).
+**
+** P1 must not be pseudo-table.  It has to be a real table with
+** multiple rows.
+**
+** If P4 is not NULL then it points to a Table object. In this case either 
+** the update or pre-update hook, or both, may be invoked. The P1 cursor must
+** have been positioned using OP_NotFound prior to invoking this opcode in 
+** this case. Specifically, if one is configured, the pre-update hook is 
+** invoked if P4 is not NULL. The update-hook is invoked if one is configured, 
+** P4 is not NULL, and the OPFLAG_NCHANGE flag is set in P2.
+**
+** If the OPFLAG_ISUPDATE flag is set in P2, then P3 contains the address
+** of the memory cell that contains the value that the rowid of the row will
+** be set to by the update.
+*/
+case OP_Delete: {
+  VdbeCursor *pC;
+  const char *zDb;
+  Table *pTab;
+  int opflags;
+
+  opflags = pOp->p2;
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+  assert( pC->eCurType==CURTYPE_BTREE );
+  assert( pC->uc.pCursor!=0 );
+  assert( pC->deferredMoveto==0 );
+
+#ifdef SQLITE_DEBUG
+  if( pOp->p4type==P4_TABLE && HasRowid(pOp->p4.pTab) && pOp->p5==0 ){
+    /* If p5 is zero, the seek operation that positioned the cursor prior to
+    ** OP_Delete will have also set the pC->movetoTarget field to the rowid of
+    ** the row that is being deleted */
+    i64 iKey = sqlite3BtreeIntegerKey(pC->uc.pCursor);
+    assert( pC->movetoTarget==iKey );
+  }
+#endif
+
+  /* If the update-hook or pre-update-hook will be invoked, set zDb to
+  ** the name of the db to pass as to it. Also set local pTab to a copy
+  ** of p4.pTab. Finally, if p5 is true, indicating that this cursor was
+  ** last moved with OP_Next or OP_Prev, not Seek or NotFound, set 
+  ** VdbeCursor.movetoTarget to the current rowid.  */
+  if( pOp->p4type==P4_TABLE && HAS_UPDATE_HOOK(db) ){
+    assert( pC->iDb>=0 );
+    assert( pOp->p4.pTab!=0 );
+    zDb = db->aDb[pC->iDb].zDbSName;
+    pTab = pOp->p4.pTab;
+    if( (pOp->p5 & OPFLAG_SAVEPOSITION)!=0 && pC->isTable ){
+      pC->movetoTarget = sqlite3BtreeIntegerKey(pC->uc.pCursor);
+    }
+  }else{
+    zDb = 0;   /* Not needed.  Silence a compiler warning. */
+    pTab = 0;  /* Not needed.  Silence a compiler warning. */
+  }
+
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+  /* Invoke the pre-update-hook if required. */
+  if( db->xPreUpdateCallback && pOp->p4.pTab && HasRowid(pTab) ){
+    assert( !(opflags & OPFLAG_ISUPDATE) || (aMem[pOp->p3].flags & MEM_Int) );
+    sqlite3VdbePreUpdateHook(p, pC,
+        (opflags & OPFLAG_ISUPDATE) ? SQLITE_UPDATE : SQLITE_DELETE, 
+        zDb, pTab, pC->movetoTarget,
+        pOp->p3
+    );
+  }
+  if( opflags & OPFLAG_ISNOOP ) break;
+#endif
+ 
+  /* Only flags that can be set are SAVEPOISTION and AUXDELETE */ 
+  assert( (pOp->p5 & ~(OPFLAG_SAVEPOSITION|OPFLAG_AUXDELETE))==0 );
+  assert( OPFLAG_SAVEPOSITION==BTREE_SAVEPOSITION );
+  assert( OPFLAG_AUXDELETE==BTREE_AUXDELETE );
+
+#ifdef SQLITE_DEBUG
+  if( p->pFrame==0 ){
+    if( pC->isEphemeral==0
+        && (pOp->p5 & OPFLAG_AUXDELETE)==0
+        && (pC->wrFlag & OPFLAG_FORDELETE)==0
+      ){
+      nExtraDelete++;
+    }
+    if( pOp->p2 & OPFLAG_NCHANGE ){
+      nExtraDelete--;
+    }
+  }
+#endif
+
+  rc = sqlite3BtreeDelete(pC->uc.pCursor, pOp->p5);
+  pC->cacheStatus = CACHE_STALE;
+  if( rc ) goto abort_due_to_error;
+
+  /* Invoke the update-hook if required. */
+  if( opflags & OPFLAG_NCHANGE ){
+    p->nChange++;
+    if( db->xUpdateCallback && HasRowid(pTab) ){
+      db->xUpdateCallback(db->pUpdateArg, SQLITE_DELETE, zDb, pTab->zName,
+          pC->movetoTarget);
+      assert( pC->iDb>=0 );
+    }
+  }
+
+  break;
+}
+/* Opcode: ResetCount * * * * *
+**
+** The value of the change counter is copied to the database handle
+** change counter (returned by subsequent calls to sqlite3_changes()).
+** Then the VMs internal change counter resets to 0.
+** This is used by trigger programs.
+*/
+case OP_ResetCount: {
+  sqlite3VdbeSetChanges(db, p->nChange);
+  p->nChange = 0;
+  break;
+}
+
+/* Opcode: SorterCompare P1 P2 P3 P4
+** Synopsis: if key(P1)!=trim(r[P3],P4) goto P2
+**
+** P1 is a sorter cursor. This instruction compares a prefix of the
+** record blob in register P3 against a prefix of the entry that 
+** the sorter cursor currently points to.  Only the first P4 fields
+** of r[P3] and the sorter record are compared.
+**
+** If either P3 or the sorter contains a NULL in one of their significant
+** fields (not counting the P4 fields at the end which are ignored) then
+** the comparison is assumed to be equal.
+**
+** Fall through to next instruction if the two records compare equal to
+** each other.  Jump to P2 if they are different.
+*/
+case OP_SorterCompare: {
+  VdbeCursor *pC;
+  int res;
+  int nKeyCol;
+
+  pC = p->apCsr[pOp->p1];
+  assert( isSorter(pC) );
+  assert( pOp->p4type==P4_INT32 );
+  pIn3 = &aMem[pOp->p3];
+  nKeyCol = pOp->p4.i;
+  res = 0;
+  rc = sqlite3VdbeSorterCompare(pC, pIn3, nKeyCol, &res);
+  VdbeBranchTaken(res!=0,2);
+  if( rc ) goto abort_due_to_error;
+  if( res ) goto jump_to_p2;
+  break;
+};
+
+/* Opcode: SorterData P1 P2 P3 * *
+** Synopsis: r[P2]=data
+**
+** Write into register P2 the current sorter data for sorter cursor P1.
+** Then clear the column header cache on cursor P3.
+**
+** This opcode is normally use to move a record out of the sorter and into
+** a register that is the source for a pseudo-table cursor created using
+** OpenPseudo.  That pseudo-table cursor is the one that is identified by
+** parameter P3.  Clearing the P3 column cache as part of this opcode saves
+** us from having to issue a separate NullRow instruction to clear that cache.
+*/
+case OP_SorterData: {
+  VdbeCursor *pC;
+
+  pOut = &aMem[pOp->p2];
+  pC = p->apCsr[pOp->p1];
+  assert( isSorter(pC) );
+  rc = sqlite3VdbeSorterRowkey(pC, pOut);
+  assert( rc!=SQLITE_OK || (pOut->flags & MEM_Blob) );
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  if( rc ) goto abort_due_to_error;
+  p->apCsr[pOp->p3]->cacheStatus = CACHE_STALE;
+  break;
+}
+
+/* Opcode: RowData P1 P2 * * *
+** Synopsis: r[P2]=data
+**
+** Write into register P2 the complete row data for cursor P1.
+** There is no interpretation of the data.  
+** It is just copied onto the P2 register exactly as 
+** it is found in the database file.
+**
+** If the P1 cursor must be pointing to a valid row (not a NULL row)
+** of a real table, not a pseudo-table.
+*/
+/* Opcode: RowKey P1 P2 * * *
+** Synopsis: r[P2]=key
+**
+** Write into register P2 the complete row key for cursor P1.
+** There is no interpretation of the data.  
+** The key is copied onto the P2 register exactly as 
+** it is found in the database file.
+**
+** If the P1 cursor must be pointing to a valid row (not a NULL row)
+** of a real table, not a pseudo-table.
+*/
+case OP_RowKey:
+case OP_RowData: {
+  VdbeCursor *pC;
+  BtCursor *pCrsr;
+  u32 n;
+
+  pOut = &aMem[pOp->p2];
+  memAboutToChange(p, pOut);
+
+  /* Note that RowKey and RowData are really exactly the same instruction */
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+  assert( pC->eCurType==CURTYPE_BTREE );
+  assert( isSorter(pC)==0 );
+  assert( pC->isTable || pOp->opcode!=OP_RowData );
+  assert( pC->isTable==0 || pOp->opcode==OP_RowData );
+  assert( pC->nullRow==0 );
+  assert( pC->uc.pCursor!=0 );
+  pCrsr = pC->uc.pCursor;
+
+  /* The OP_RowKey and OP_RowData opcodes always follow OP_NotExists or
+  ** OP_SeekRowid or OP_Rewind/Op_Next with no intervening instructions
+  ** that might invalidate the cursor.
+  ** If this where not the case, on of the following assert()s
+  ** would fail.  Should this ever change (because of changes in the code
+  ** generator) then the fix would be to insert a call to
+  ** sqlite3VdbeCursorMoveto().
+  */
+  assert( pC->deferredMoveto==0 );
+  assert( sqlite3BtreeCursorIsValid(pCrsr) );
+#if 0  /* Not required due to the previous to assert() statements */
+  rc = sqlite3VdbeCursorMoveto(pC);
+  if( rc!=SQLITE_OK ) goto abort_due_to_error;
+#endif
+
+  n = sqlite3BtreePayloadSize(pCrsr);
+  if( n>(u32)db->aLimit[SQLITE_LIMIT_LENGTH] ){
+    goto too_big;
+  }
+  testcase( n==0 );
+  if( sqlite3VdbeMemClearAndResize(pOut, MAX(n,32)) ){
+    goto no_mem;
+  }
+  pOut->n = n;
+  MemSetTypeFlag(pOut, MEM_Blob);
+  if( pC->isTable==0 ){
+    rc = sqlite3BtreeKey(pCrsr, 0, n, pOut->z);
+  }else{
+    rc = sqlite3BtreeData(pCrsr, 0, n, pOut->z);
+  }
+  if( rc ) goto abort_due_to_error;
+  pOut->enc = SQLITE_UTF8;  /* In case the blob is ever cast to text */
+  UPDATE_MAX_BLOBSIZE(pOut);
+  REGISTER_TRACE(pOp->p2, pOut);
+  break;
+}
+
+/* Opcode: Rowid P1 P2 * * *
+** Synopsis: r[P2]=rowid
+**
+** Store in register P2 an integer which is the key of the table entry that
+** P1 is currently point to.
+**
+** P1 can be either an ordinary table or a virtual table.  There used to
+** be a separate OP_VRowid opcode for use with virtual tables, but this
+** one opcode now works for both table types.
+*/
+case OP_Rowid: {                 /* out2 */
+  VdbeCursor *pC;
+  i64 v;
+  sqlite3_vtab *pVtab;
+  const sqlite3_module *pModule;
+
+  pOut = out2Prerelease(p, pOp);
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+  assert( pC->eCurType!=CURTYPE_PSEUDO || pC->nullRow );
+  if( pC->nullRow ){
+    pOut->flags = MEM_Null;
+    break;
+  }else if( pC->deferredMoveto ){
+    v = pC->movetoTarget;
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  }else if( pC->eCurType==CURTYPE_VTAB ){
+    assert( pC->uc.pVCur!=0 );
+    pVtab = pC->uc.pVCur->pVtab;
+    pModule = pVtab->pModule;
+    assert( pModule->xRowid );
+    rc = pModule->xRowid(pC->uc.pVCur, &v);
+    sqlite3VtabImportErrmsg(p, pVtab);
+    if( rc ) goto abort_due_to_error;
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+  }else{
+    assert( pC->eCurType==CURTYPE_BTREE );
+    assert( pC->uc.pCursor!=0 );
+    rc = sqlite3VdbeCursorRestore(pC);
+    if( rc ) goto abort_due_to_error;
+    if( pC->nullRow ){
+      pOut->flags = MEM_Null;
+      break;
+    }
+    v = sqlite3BtreeIntegerKey(pC->uc.pCursor);
+  }
+  pOut->u.i = v;
+  break;
+}
+
+/* Opcode: NullRow P1 * * * *
+**
+** Move the cursor P1 to a null row.  Any OP_Column operations
+** that occur while the cursor is on the null row will always
+** write a NULL.
+*/
+case OP_NullRow: {
+  VdbeCursor *pC;
+
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+  pC->nullRow = 1;
+  pC->cacheStatus = CACHE_STALE;
+  if( pC->eCurType==CURTYPE_BTREE ){
+    assert( pC->uc.pCursor!=0 );
+    sqlite3BtreeClearCursor(pC->uc.pCursor);
+  }
+  break;
+}
+
+/* Opcode: Last P1 P2 P3 * *
+**
+** The next use of the Rowid or Column or Prev instruction for P1 
+** will refer to the last entry in the database table or index.
+** If the table or index is empty and P2>0, then jump immediately to P2.
+** If P2 is 0 or if the table or index is not empty, fall through
+** to the following instruction.
+**
+** This opcode leaves the cursor configured to move in reverse order,
+** from the end toward the beginning.  In other words, the cursor is
+** configured to use Prev, not Next.
+*/
+case OP_Last: {        /* jump */
+  VdbeCursor *pC;
+  BtCursor *pCrsr;
+  int res;
+
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+  assert( pC->eCurType==CURTYPE_BTREE );
+  pCrsr = pC->uc.pCursor;
+  res = 0;
+  assert( pCrsr!=0 );
+  rc = sqlite3BtreeLast(pCrsr, &res);
+  pC->nullRow = (u8)res;
+  pC->deferredMoveto = 0;
+  pC->cacheStatus = CACHE_STALE;
+  pC->seekResult = pOp->p3;
+#ifdef SQLITE_DEBUG
+  pC->seekOp = OP_Last;
+#endif
+  if( rc ) goto abort_due_to_error;
+  if( pOp->p2>0 ){
+    VdbeBranchTaken(res!=0,2);
+    if( res ) goto jump_to_p2;
+  }
+  break;
+}
+
+
+/* Opcode: Sort P1 P2 * * *
+**
+** This opcode does exactly the same thing as OP_Rewind except that
+** it increments an undocumented global variable used for testing.
+**
+** Sorting is accomplished by writing records into a sorting index,
+** then rewinding that index and playing it back from beginning to
+** end.  We use the OP_Sort opcode instead of OP_Rewind to do the
+** rewinding so that the global variable will be incremented and
+** regression tests can determine whether or not the optimizer is
+** correctly optimizing out sorts.
+*/
+case OP_SorterSort:    /* jump */
+case OP_Sort: {        /* jump */
+#ifdef SQLITE_TEST
+  sqlite3_sort_count++;
+  sqlite3_search_count--;
+#endif
+  p->aCounter[SQLITE_STMTSTATUS_SORT]++;
+  /* Fall through into OP_Rewind */
+}
+/* Opcode: Rewind P1 P2 * * *
+**
+** The next use of the Rowid or Column or Next instruction for P1 
+** will refer to the first entry in the database table or index.
+** If the table or index is empty, jump immediately to P2.
+** If the table or index is not empty, fall through to the following 
+** instruction.
+**
+** This opcode leaves the cursor configured to move in forward order,
+** from the beginning toward the end.  In other words, the cursor is
+** configured to use Next, not Prev.
+*/
+case OP_Rewind: {        /* jump */
+  VdbeCursor *pC;
+  BtCursor *pCrsr;
+  int res;
+
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+  assert( isSorter(pC)==(pOp->opcode==OP_SorterSort) );
+  res = 1;
+#ifdef SQLITE_DEBUG
+  pC->seekOp = OP_Rewind;
+#endif
+  if( isSorter(pC) ){
+    rc = sqlite3VdbeSorterRewind(pC, &res);
+  }else{
+    assert( pC->eCurType==CURTYPE_BTREE );
+    pCrsr = pC->uc.pCursor;
+    assert( pCrsr );
+    rc = sqlite3BtreeFirst(pCrsr, &res);
+    pC->deferredMoveto = 0;
+    pC->cacheStatus = CACHE_STALE;
+  }
+  if( rc ) goto abort_due_to_error;
+  pC->nullRow = (u8)res;
+  assert( pOp->p2>0 && pOp->p2<p->nOp );
+  VdbeBranchTaken(res!=0,2);
+  if( res ) goto jump_to_p2;
+  break;
+}
+
+/* Opcode: Next P1 P2 P3 P4 P5
+**
+** Advance cursor P1 so that it points to the next key/data pair in its
+** table or index.  If there are no more key/value pairs then fall through
+** to the following instruction.  But if the cursor advance was successful,
+** jump immediately to P2.
+**
+** The Next opcode is only valid following an SeekGT, SeekGE, or
+** OP_Rewind opcode used to position the cursor.  Next is not allowed
+** to follow SeekLT, SeekLE, or OP_Last.
+**
+** The P1 cursor must be for a real table, not a pseudo-table.  P1 must have
+** been opened prior to this opcode or the program will segfault.
+**
+** The P3 value is a hint to the btree implementation. If P3==1, that
+** means P1 is an SQL index and that this instruction could have been
+** omitted if that index had been unique.  P3 is usually 0.  P3 is
+** always either 0 or 1.
+**
+** P4 is always of type P4_ADVANCE. The function pointer points to
+** sqlite3BtreeNext().
+**
+** If P5 is positive and the jump is taken, then event counter
+** number P5-1 in the prepared statement is incremented.
+**
+** See also: Prev, NextIfOpen
+*/
+/* Opcode: NextIfOpen P1 P2 P3 P4 P5
+**
+** This opcode works just like Next except that if cursor P1 is not
+** open it behaves a no-op.
+*/
+/* Opcode: Prev P1 P2 P3 P4 P5
+**
+** Back up cursor P1 so that it points to the previous key/data pair in its
+** table or index.  If there is no previous key/value pairs then fall through
+** to the following instruction.  But if the cursor backup was successful,
+** jump immediately to P2.
+**
+**
+** The Prev opcode is only valid following an SeekLT, SeekLE, or
+** OP_Last opcode used to position the cursor.  Prev is not allowed
+** to follow SeekGT, SeekGE, or OP_Rewind.
+**
+** The P1 cursor must be for a real table, not a pseudo-table.  If P1 is
+** not open then the behavior is undefined.
+**
+** The P3 value is a hint to the btree implementation. If P3==1, that
+** means P1 is an SQL index and that this instruction could have been
+** omitted if that index had been unique.  P3 is usually 0.  P3 is
+** always either 0 or 1.
+**
+** P4 is always of type P4_ADVANCE. The function pointer points to
+** sqlite3BtreePrevious().
+**
+** If P5 is positive and the jump is taken, then event counter
+** number P5-1 in the prepared statement is incremented.
+*/
+/* Opcode: PrevIfOpen P1 P2 P3 P4 P5
+**
+** This opcode works just like Prev except that if cursor P1 is not
+** open it behaves a no-op.
+*/
+case OP_SorterNext: {  /* jump */
+  VdbeCursor *pC;
+  int res;
+
+  pC = p->apCsr[pOp->p1];
+  assert( isSorter(pC) );
+  res = 0;
+  rc = sqlite3VdbeSorterNext(db, pC, &res);
+  goto next_tail;
+case OP_PrevIfOpen:    /* jump */
+case OP_NextIfOpen:    /* jump */
+  if( p->apCsr[pOp->p1]==0 ) break;
+  /* Fall through */
+case OP_Prev:          /* jump */
+case OP_Next:          /* jump */
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  assert( pOp->p5<ArraySize(p->aCounter) );
+  pC = p->apCsr[pOp->p1];
+  res = pOp->p3;
+  assert( pC!=0 );
+  assert( pC->deferredMoveto==0 );
+  assert( pC->eCurType==CURTYPE_BTREE );
+  assert( res==0 || (res==1 && pC->isTable==0) );
+  testcase( res==1 );
+  assert( pOp->opcode!=OP_Next || pOp->p4.xAdvance==sqlite3BtreeNext );
+  assert( pOp->opcode!=OP_Prev || pOp->p4.xAdvance==sqlite3BtreePrevious );
+  assert( pOp->opcode!=OP_NextIfOpen || pOp->p4.xAdvance==sqlite3BtreeNext );
+  assert( pOp->opcode!=OP_PrevIfOpen || pOp->p4.xAdvance==sqlite3BtreePrevious);
+
+  /* The Next opcode is only used after SeekGT, SeekGE, and Rewind.
+  ** The Prev opcode is only used after SeekLT, SeekLE, and Last. */
+  assert( pOp->opcode!=OP_Next || pOp->opcode!=OP_NextIfOpen
+       || pC->seekOp==OP_SeekGT || pC->seekOp==OP_SeekGE
+       || pC->seekOp==OP_Rewind || pC->seekOp==OP_Found);
+  assert( pOp->opcode!=OP_Prev || pOp->opcode!=OP_PrevIfOpen
+       || pC->seekOp==OP_SeekLT || pC->seekOp==OP_SeekLE
+       || pC->seekOp==OP_Last );
+
+  rc = pOp->p4.xAdvance(pC->uc.pCursor, &res);
+next_tail:
+  pC->cacheStatus = CACHE_STALE;
+  VdbeBranchTaken(res==0,2);
+  if( rc ) goto abort_due_to_error;
+  if( res==0 ){
+    pC->nullRow = 0;
+    p->aCounter[pOp->p5]++;
+#ifdef SQLITE_TEST
+    sqlite3_search_count++;
+#endif
+    goto jump_to_p2_and_check_for_interrupt;
+  }else{
+    pC->nullRow = 1;
+  }
+  goto check_for_interrupt;
+}
+
+/* Opcode: IdxInsert P1 P2 P3 * P5
+** Synopsis: key=r[P2]
+**
+** Register P2 holds an SQL index key made using the
+** MakeRecord instructions.  This opcode writes that key
+** into the index P1.  Data for the entry is nil.
+**
+** P3 is a flag that provides a hint to the b-tree layer that this
+** insert is likely to be an append.
+**
+** If P5 has the OPFLAG_NCHANGE bit set, then the change counter is
+** incremented by this instruction.  If the OPFLAG_NCHANGE bit is clear,
+** then the change counter is unchanged.
+**
+** If P5 has the OPFLAG_USESEEKRESULT bit set, then the cursor must have
+** just done a seek to the spot where the new entry is to be inserted.
+** This flag avoids doing an extra seek.
+**
+** This instruction only works for indices.  The equivalent instruction
+** for tables is OP_Insert.
+*/
+case OP_SorterInsert:       /* in2 */
+case OP_IdxInsert: {        /* in2 */
+  VdbeCursor *pC;
+  BtreePayload x;
+
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+  assert( isSorter(pC)==(pOp->opcode==OP_SorterInsert) );
+  pIn2 = &aMem[pOp->p2];
+  assert( pIn2->flags & MEM_Blob );
+  if( pOp->p5 & OPFLAG_NCHANGE ) p->nChange++;
+  assert( pC->eCurType==CURTYPE_BTREE || pOp->opcode==OP_SorterInsert );
+  assert( pC->isTable==0 );
+  rc = ExpandBlob(pIn2);
+  if( rc ) goto abort_due_to_error;
+  if( pOp->opcode==OP_SorterInsert ){
+    rc = sqlite3VdbeSorterWrite(pC, pIn2);
+  }else{
+    x.nKey = pIn2->n;
+    x.pKey = pIn2->z;
+    rc = sqlite3BtreeInsert(pC->uc.pCursor, &x, pOp->p3, 
+        ((pOp->p5 & OPFLAG_USESEEKRESULT) ? pC->seekResult : 0)
+        );
+    assert( pC->deferredMoveto==0 );
+    pC->cacheStatus = CACHE_STALE;
+  }
+  if( rc) goto abort_due_to_error;
+  break;
+}
+
+/* Opcode: IdxDelete P1 P2 P3 * *
+** Synopsis: key=r[P2@P3]
+**
+** The content of P3 registers starting at register P2 form
+** an unpacked index key. This opcode removes that entry from the 
+** index opened by cursor P1.
+*/
+case OP_IdxDelete: {
+  VdbeCursor *pC;
+  BtCursor *pCrsr;
+  int res;
+  UnpackedRecord r;
+
+  assert( pOp->p3>0 );
+  assert( pOp->p2>0 && pOp->p2+pOp->p3<=(p->nMem+1 - p->nCursor)+1 );
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+  assert( pC->eCurType==CURTYPE_BTREE );
+  pCrsr = pC->uc.pCursor;
+  assert( pCrsr!=0 );
+  assert( pOp->p5==0 );
+  r.pKeyInfo = pC->pKeyInfo;
+  r.nField = (u16)pOp->p3;
+  r.default_rc = 0;
+  r.aMem = &aMem[pOp->p2];
+  rc = sqlite3BtreeMovetoUnpacked(pCrsr, &r, 0, 0, &res);
+  if( rc ) goto abort_due_to_error;
+  if( res==0 ){
+    rc = sqlite3BtreeDelete(pCrsr, BTREE_AUXDELETE);
+    if( rc ) goto abort_due_to_error;
+  }
+  assert( pC->deferredMoveto==0 );
+  pC->cacheStatus = CACHE_STALE;
+  break;
+}
+
+/* Opcode: Seek P1 * P3 P4 *
+** Synopsis: Move P3 to P1.rowid
+**
+** P1 is an open index cursor and P3 is a cursor on the corresponding
+** table.  This opcode does a deferred seek of the P3 table cursor
+** to the row that corresponds to the current row of P1.
+**
+** This is a deferred seek.  Nothing actually happens until
+** the cursor is used to read a record.  That way, if no reads
+** occur, no unnecessary I/O happens.
+**
+** P4 may be an array of integers (type P4_INTARRAY) containing
+** one entry for each column in the P3 table.  If array entry a(i)
+** is non-zero, then reading column a(i)-1 from cursor P3 is 
+** equivalent to performing the deferred seek and then reading column i 
+** from P1.  This information is stored in P3 and used to redirect
+** reads against P3 over to P1, thus possibly avoiding the need to
+** seek and read cursor P3.
+*/
+/* Opcode: IdxRowid P1 P2 * * *
+** Synopsis: r[P2]=rowid
+**
+** Write into register P2 an integer which is the last entry in the record at
+** the end of the index key pointed to by cursor P1.  This integer should be
+** the rowid of the table entry to which this index entry points.
+**
+** See also: Rowid, MakeRecord.
+*/
+case OP_Seek:
+case OP_IdxRowid: {              /* out2 */
+  VdbeCursor *pC;                /* The P1 index cursor */
+  VdbeCursor *pTabCur;           /* The P2 table cursor (OP_Seek only) */
+  i64 rowid;                     /* Rowid that P1 current points to */
+
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+  assert( pC->eCurType==CURTYPE_BTREE );
+  assert( pC->uc.pCursor!=0 );
+  assert( pC->isTable==0 );
+  assert( pC->deferredMoveto==0 );
+  assert( !pC->nullRow || pOp->opcode==OP_IdxRowid );
+
+  /* The IdxRowid and Seek opcodes are combined because of the commonality
+  ** of sqlite3VdbeCursorRestore() and sqlite3VdbeIdxRowid(). */
+  rc = sqlite3VdbeCursorRestore(pC);
+
+  /* sqlite3VbeCursorRestore() can only fail if the record has been deleted
+  ** out from under the cursor.  That will never happens for an IdxRowid
+  ** or Seek opcode */
+  if( NEVER(rc!=SQLITE_OK) ) goto abort_due_to_error;
+
+  if( !pC->nullRow ){
+    rowid = 0;  /* Not needed.  Only used to silence a warning. */
+    rc = sqlite3VdbeIdxRowid(db, pC->uc.pCursor, &rowid);
+    if( rc!=SQLITE_OK ){
+      goto abort_due_to_error;
+    }
+    if( pOp->opcode==OP_Seek ){
+      assert( pOp->p3>=0 && pOp->p3<p->nCursor );
+      pTabCur = p->apCsr[pOp->p3];
+      assert( pTabCur!=0 );
+      assert( pTabCur->eCurType==CURTYPE_BTREE );
+      assert( pTabCur->uc.pCursor!=0 );
+      assert( pTabCur->isTable );
+      pTabCur->nullRow = 0;
+      pTabCur->movetoTarget = rowid;
+      pTabCur->deferredMoveto = 1;
+      assert( pOp->p4type==P4_INTARRAY || pOp->p4.ai==0 );
+      pTabCur->aAltMap = pOp->p4.ai;
+      pTabCur->pAltCursor = pC;
+    }else{
+      pOut = out2Prerelease(p, pOp);
+      pOut->u.i = rowid;
+      pOut->flags = MEM_Int;
+    }
+  }else{
+    assert( pOp->opcode==OP_IdxRowid );
+    sqlite3VdbeMemSetNull(&aMem[pOp->p2]);
+  }
+  break;
+}
+
+/* Opcode: IdxGE P1 P2 P3 P4 P5
+** Synopsis: key=r[P3@P4]
+**
+** The P4 register values beginning with P3 form an unpacked index 
+** key that omits the PRIMARY KEY.  Compare this key value against the index 
+** that P1 is currently pointing to, ignoring the PRIMARY KEY or ROWID 
+** fields at the end.
+**
+** If the P1 index entry is greater than or equal to the key value
+** then jump to P2.  Otherwise fall through to the next instruction.
+*/
+/* Opcode: IdxGT P1 P2 P3 P4 P5
+** Synopsis: key=r[P3@P4]
+**
+** The P4 register values beginning with P3 form an unpacked index 
+** key that omits the PRIMARY KEY.  Compare this key value against the index 
+** that P1 is currently pointing to, ignoring the PRIMARY KEY or ROWID 
+** fields at the end.
+**
+** If the P1 index entry is greater than the key value
+** then jump to P2.  Otherwise fall through to the next instruction.
+*/
+/* Opcode: IdxLT P1 P2 P3 P4 P5
+** Synopsis: key=r[P3@P4]
+**
+** The P4 register values beginning with P3 form an unpacked index 
+** key that omits the PRIMARY KEY or ROWID.  Compare this key value against
+** the index that P1 is currently pointing to, ignoring the PRIMARY KEY or
+** ROWID on the P1 index.
+**
+** If the P1 index entry is less than the key value then jump to P2.
+** Otherwise fall through to the next instruction.
+*/
+/* Opcode: IdxLE P1 P2 P3 P4 P5
+** Synopsis: key=r[P3@P4]
+**
+** The P4 register values beginning with P3 form an unpacked index 
+** key that omits the PRIMARY KEY or ROWID.  Compare this key value against
+** the index that P1 is currently pointing to, ignoring the PRIMARY KEY or
+** ROWID on the P1 index.
+**
+** If the P1 index entry is less than or equal to the key value then jump
+** to P2. Otherwise fall through to the next instruction.
+*/
+case OP_IdxLE:          /* jump */
+case OP_IdxGT:          /* jump */
+case OP_IdxLT:          /* jump */
+case OP_IdxGE:  {       /* jump */
+  VdbeCursor *pC;
+  int res;
+  UnpackedRecord r;
+
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+  assert( pC->isOrdered );
+  assert( pC->eCurType==CURTYPE_BTREE );
+  assert( pC->uc.pCursor!=0);
+  assert( pC->deferredMoveto==0 );
+  assert( pOp->p5==0 || pOp->p5==1 );
+  assert( pOp->p4type==P4_INT32 );
+  r.pKeyInfo = pC->pKeyInfo;
+  r.nField = (u16)pOp->p4.i;
+  if( pOp->opcode<OP_IdxLT ){
+    assert( pOp->opcode==OP_IdxLE || pOp->opcode==OP_IdxGT );
+    r.default_rc = -1;
+  }else{
+    assert( pOp->opcode==OP_IdxGE || pOp->opcode==OP_IdxLT );
+    r.default_rc = 0;
+  }
+  r.aMem = &aMem[pOp->p3];
+#ifdef SQLITE_DEBUG
+  { int i; for(i=0; i<r.nField; i++) assert( memIsValid(&r.aMem[i]) ); }
+#endif
+  res = 0;  /* Not needed.  Only used to silence a warning. */
+  rc = sqlite3VdbeIdxKeyCompare(db, pC, &r, &res);
+  assert( (OP_IdxLE&1)==(OP_IdxLT&1) && (OP_IdxGE&1)==(OP_IdxGT&1) );
+  if( (pOp->opcode&1)==(OP_IdxLT&1) ){
+    assert( pOp->opcode==OP_IdxLE || pOp->opcode==OP_IdxLT );
+    res = -res;
+  }else{
+    assert( pOp->opcode==OP_IdxGE || pOp->opcode==OP_IdxGT );
+    res++;
+  }
+  VdbeBranchTaken(res>0,2);
+  if( rc ) goto abort_due_to_error;
+  if( res>0 ) goto jump_to_p2;
+  break;
+}
+
+/* Opcode: Destroy P1 P2 P3 * *
+**
+** Delete an entire database table or index whose root page in the database
+** file is given by P1.
+**
+** The table being destroyed is in the main database file if P3==0.  If
+** P3==1 then the table to be clear is in the auxiliary database file
+** that is used to store tables create using CREATE TEMPORARY TABLE.
+**
+** If AUTOVACUUM is enabled then it is possible that another root page
+** might be moved into the newly deleted root page in order to keep all
+** root pages contiguous at the beginning of the database.  The former
+** value of the root page that moved - its value before the move occurred -
+** is stored in register P2.  If no page 
+** movement was required (because the table being dropped was already 
+** the last one in the database) then a zero is stored in register P2.
+** If AUTOVACUUM is disabled then a zero is stored in register P2.
+**
+** See also: Clear
+*/
+case OP_Destroy: {     /* out2 */
+  int iMoved;
+  int iDb;
+
+  assert( p->readOnly==0 );
+  assert( pOp->p1>1 );
+  pOut = out2Prerelease(p, pOp);
+  pOut->flags = MEM_Null;
+  if( db->nVdbeRead > db->nVDestroy+1 ){
+    rc = SQLITE_LOCKED;
+    p->errorAction = OE_Abort;
+    goto abort_due_to_error;
+  }else{
+    iDb = pOp->p3;
+    assert( DbMaskTest(p->btreeMask, iDb) );
+    iMoved = 0;  /* Not needed.  Only to silence a warning. */
+    rc = sqlite3BtreeDropTable(db->aDb[iDb].pBt, pOp->p1, &iMoved);
+    pOut->flags = MEM_Int;
+    pOut->u.i = iMoved;
+    if( rc ) goto abort_due_to_error;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    if( iMoved!=0 ){
+      sqlite3RootPageMoved(db, iDb, iMoved, pOp->p1);
+      /* All OP_Destroy operations occur on the same btree */
+      assert( resetSchemaOnFault==0 || resetSchemaOnFault==iDb+1 );
+      resetSchemaOnFault = iDb+1;
+    }
+#endif
+  }
+  break;
+}
+
+/* Opcode: Clear P1 P2 P3
+**
+** Delete all contents of the database table or index whose root page
+** in the database file is given by P1.  But, unlike Destroy, do not
+** remove the table or index from the database file.
+**
+** The table being clear is in the main database file if P2==0.  If
+** P2==1 then the table to be clear is in the auxiliary database file
+** that is used to store tables create using CREATE TEMPORARY TABLE.
+**
+** If the P3 value is non-zero, then the table referred to must be an
+** intkey table (an SQL table, not an index). In this case the row change 
+** count is incremented by the number of rows in the table being cleared. 
+** If P3 is greater than zero, then the value stored in register P3 is
+** also incremented by the number of rows in the table being cleared.
+**
+** See also: Destroy
+*/
+case OP_Clear: {
+  int nChange;
+ 
+  nChange = 0;
+  assert( p->readOnly==0 );
+  assert( DbMaskTest(p->btreeMask, pOp->p2) );
+  rc = sqlite3BtreeClearTable(
+      db->aDb[pOp->p2].pBt, pOp->p1, (pOp->p3 ? &nChange : 0)
+  );
+  if( pOp->p3 ){
+    p->nChange += nChange;
+    if( pOp->p3>0 ){
+      assert( memIsValid(&aMem[pOp->p3]) );
+      memAboutToChange(p, &aMem[pOp->p3]);
+      aMem[pOp->p3].u.i += nChange;
+    }
+  }
+  if( rc ) goto abort_due_to_error;
+  break;
+}
+
+/* Opcode: ResetSorter P1 * * * *
+**
+** Delete all contents from the ephemeral table or sorter
+** that is open on cursor P1.
+**
+** This opcode only works for cursors used for sorting and
+** opened with OP_OpenEphemeral or OP_SorterOpen.
+*/
+case OP_ResetSorter: {
+  VdbeCursor *pC;
+ 
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+  if( isSorter(pC) ){
+    sqlite3VdbeSorterReset(db, pC->uc.pSorter);
+  }else{
+    assert( pC->eCurType==CURTYPE_BTREE );
+    assert( pC->isEphemeral );
+    rc = sqlite3BtreeClearTableOfCursor(pC->uc.pCursor);
+    if( rc ) goto abort_due_to_error;
+  }
+  break;
+}
+
+/* Opcode: CreateTable P1 P2 * * *
+** Synopsis: r[P2]=root iDb=P1
+**
+** Allocate a new table in the main database file if P1==0 or in the
+** auxiliary database file if P1==1 or in an attached database if
+** P1>1.  Write the root page number of the new table into
+** register P2
+**
+** The difference between a table and an index is this:  A table must
+** have a 4-byte integer key and can have arbitrary data.  An index
+** has an arbitrary key but no data.
+**
+** See also: CreateIndex
+*/
+/* Opcode: CreateIndex P1 P2 * * *
+** Synopsis: r[P2]=root iDb=P1
+**
+** Allocate a new index in the main database file if P1==0 or in the
+** auxiliary database file if P1==1 or in an attached database if
+** P1>1.  Write the root page number of the new table into
+** register P2.
+**
+** See documentation on OP_CreateTable for additional information.
+*/
+case OP_CreateIndex:            /* out2 */
+case OP_CreateTable: {          /* out2 */
+  int pgno;
+  int flags;
+  Db *pDb;
+
+  pOut = out2Prerelease(p, pOp);
+  pgno = 0;
+  assert( pOp->p1>=0 && pOp->p1<db->nDb );
+  assert( DbMaskTest(p->btreeMask, pOp->p1) );
+  assert( p->readOnly==0 );
+  pDb = &db->aDb[pOp->p1];
+  assert( pDb->pBt!=0 );
+  if( pOp->opcode==OP_CreateTable ){
+    /* flags = BTREE_INTKEY; */
+    flags = BTREE_INTKEY;
+  }else{
+    flags = BTREE_BLOBKEY;
+  }
+  rc = sqlite3BtreeCreateTable(pDb->pBt, &pgno, flags);
+  if( rc ) goto abort_due_to_error;
+  pOut->u.i = pgno;
+  break;
+}
+
+/* Opcode: ParseSchema P1 * * P4 *
+**
+** Read and parse all entries from the SQLITE_MASTER table of database P1
+** that match the WHERE clause P4. 
+**
+** This opcode invokes the parser to create a new virtual machine,
+** then runs the new virtual machine.  It is thus a re-entrant opcode.
+*/
+case OP_ParseSchema: {
+  int iDb;
+  const char *zMaster;
+  char *zSql;
+  InitData initData;
+
+  /* Any prepared statement that invokes this opcode will hold mutexes
+  ** on every btree.  This is a prerequisite for invoking 
+  ** sqlite3InitCallback().
+  */
+#ifdef SQLITE_DEBUG
+  for(iDb=0; iDb<db->nDb; iDb++){
+    assert( iDb==1 || sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) );
+  }
+#endif
+
+  iDb = pOp->p1;
+  assert( iDb>=0 && iDb<db->nDb );
+  assert( DbHasProperty(db, iDb, DB_SchemaLoaded) );
+  /* Used to be a conditional */ {
+    zMaster = SCHEMA_TABLE(iDb);
+    initData.db = db;
+    initData.iDb = pOp->p1;
+    initData.pzErrMsg = &p->zErrMsg;
+    zSql = sqlite3MPrintf(db,
+       "SELECT name, rootpage, sql FROM '%q'.%s WHERE %s ORDER BY rowid",
+       db->aDb[iDb].zDbSName, zMaster, pOp->p4.z);
+    if( zSql==0 ){
+      rc = SQLITE_NOMEM_BKPT;
+    }else{
+      assert( db->init.busy==0 );
+      db->init.busy = 1;
+      initData.rc = SQLITE_OK;
+      assert( !db->mallocFailed );
+      rc = sqlite3_exec(db, zSql, sqlite3InitCallback, &initData, 0);
+      if( rc==SQLITE_OK ) rc = initData.rc;
+      sqlite3DbFree(db, zSql);
+      db->init.busy = 0;
+    }
+  }
+  if( rc ){
+    sqlite3ResetAllSchemasOfConnection(db);
+    if( rc==SQLITE_NOMEM ){
+      goto no_mem;
+    }
+    goto abort_due_to_error;
+  }
+  break;  
+}
+
+#if !defined(SQLITE_OMIT_ANALYZE)
+/* Opcode: LoadAnalysis P1 * * * *
+**
+** Read the sqlite_stat1 table for database P1 and load the content
+** of that table into the internal index hash table.  This will cause
+** the analysis to be used when preparing all subsequent queries.
+*/
+case OP_LoadAnalysis: {
+  assert( pOp->p1>=0 && pOp->p1<db->nDb );
+  rc = sqlite3AnalysisLoad(db, pOp->p1);
+  if( rc ) goto abort_due_to_error;
+  break;  
+}
+#endif /* !defined(SQLITE_OMIT_ANALYZE) */
+
+/* Opcode: DropTable P1 * * P4 *
+**
+** Remove the internal (in-memory) data structures that describe
+** the table named P4 in database P1.  This is called after a table
+** is dropped from disk (using the Destroy opcode) in order to keep 
+** the internal representation of the
+** schema consistent with what is on disk.
+*/
+case OP_DropTable: {
+  sqlite3UnlinkAndDeleteTable(db, pOp->p1, pOp->p4.z);
+  break;
+}
+
+/* Opcode: DropIndex P1 * * P4 *
+**
+** Remove the internal (in-memory) data structures that describe
+** the index named P4 in database P1.  This is called after an index
+** is dropped from disk (using the Destroy opcode)
+** in order to keep the internal representation of the
+** schema consistent with what is on disk.
+*/
+case OP_DropIndex: {
+  sqlite3UnlinkAndDeleteIndex(db, pOp->p1, pOp->p4.z);
+  break;
+}
+
+/* Opcode: DropTrigger P1 * * P4 *
+**
+** Remove the internal (in-memory) data structures that describe
+** the trigger named P4 in database P1.  This is called after a trigger
+** is dropped from disk (using the Destroy opcode) in order to keep 
+** the internal representation of the
+** schema consistent with what is on disk.
+*/
+case OP_DropTrigger: {
+  sqlite3UnlinkAndDeleteTrigger(db, pOp->p1, pOp->p4.z);
+  break;
+}
+
+
+#ifndef SQLITE_OMIT_INTEGRITY_CHECK
+/* Opcode: IntegrityCk P1 P2 P3 P4 P5
+**
+** Do an analysis of the currently open database.  Store in
+** register P1 the text of an error message describing any problems.
+** If no problems are found, store a NULL in register P1.
+**
+** The register P3 contains the maximum number of allowed errors.
+** At most reg(P3) errors will be reported.
+** In other words, the analysis stops as soon as reg(P1) errors are 
+** seen.  Reg(P1) is updated with the number of errors remaining.
+**
+** The root page numbers of all tables in the database are integers
+** stored in P4_INTARRAY argument.
+**
+** If P5 is not zero, the check is done on the auxiliary database
+** file, not the main database file.
+**
+** This opcode is used to implement the integrity_check pragma.
+*/
+case OP_IntegrityCk: {
+  int nRoot;      /* Number of tables to check.  (Number of root pages.) */
+  int *aRoot;     /* Array of rootpage numbers for tables to be checked */
+  int nErr;       /* Number of errors reported */
+  char *z;        /* Text of the error report */
+  Mem *pnErr;     /* Register keeping track of errors remaining */
+
+  assert( p->bIsReader );
+  nRoot = pOp->p2;
+  aRoot = pOp->p4.ai;
+  assert( nRoot>0 );
+  assert( aRoot[nRoot]==0 );
+  assert( pOp->p3>0 && pOp->p3<=(p->nMem+1 - p->nCursor) );
+  pnErr = &aMem[pOp->p3];
+  assert( (pnErr->flags & MEM_Int)!=0 );
+  assert( (pnErr->flags & (MEM_Str|MEM_Blob))==0 );
+  pIn1 = &aMem[pOp->p1];
+  assert( pOp->p5<db->nDb );
+  assert( DbMaskTest(p->btreeMask, pOp->p5) );
+  z = sqlite3BtreeIntegrityCheck(db->aDb[pOp->p5].pBt, aRoot, nRoot,
+                                 (int)pnErr->u.i, &nErr);
+  pnErr->u.i -= nErr;
+  sqlite3VdbeMemSetNull(pIn1);
+  if( nErr==0 ){
+    assert( z==0 );
+  }else if( z==0 ){
+    goto no_mem;
+  }else{
+    sqlite3VdbeMemSetStr(pIn1, z, -1, SQLITE_UTF8, sqlite3_free);
+  }
+  UPDATE_MAX_BLOBSIZE(pIn1);
+  sqlite3VdbeChangeEncoding(pIn1, encoding);
+  break;
+}
+#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
+
+/* Opcode: RowSetAdd P1 P2 * * *
+** Synopsis: rowset(P1)=r[P2]
+**
+** Insert the integer value held by register P2 into a boolean index
+** held in register P1.
+**
+** An assertion fails if P2 is not an integer.
+*/
+case OP_RowSetAdd: {       /* in1, in2 */
+  pIn1 = &aMem[pOp->p1];
+  pIn2 = &aMem[pOp->p2];
+  assert( (pIn2->flags & MEM_Int)!=0 );
+  if( (pIn1->flags & MEM_RowSet)==0 ){
+    sqlite3VdbeMemSetRowSet(pIn1);
+    if( (pIn1->flags & MEM_RowSet)==0 ) goto no_mem;
+  }
+  sqlite3RowSetInsert(pIn1->u.pRowSet, pIn2->u.i);
+  break;
+}
+
+/* Opcode: RowSetRead P1 P2 P3 * *
+** Synopsis: r[P3]=rowset(P1)
+**
+** Extract the smallest value from boolean index P1 and put that value into
+** register P3.  Or, if boolean index P1 is initially empty, leave P3
+** unchanged and jump to instruction P2.
+*/
+case OP_RowSetRead: {       /* jump, in1, out3 */
+  i64 val;
+
+  pIn1 = &aMem[pOp->p1];
+  if( (pIn1->flags & MEM_RowSet)==0 
+   || sqlite3RowSetNext(pIn1->u.pRowSet, &val)==0
+  ){
+    /* The boolean index is empty */
+    sqlite3VdbeMemSetNull(pIn1);
+    VdbeBranchTaken(1,2);
+    goto jump_to_p2_and_check_for_interrupt;
+  }else{
+    /* A value was pulled from the index */
+    VdbeBranchTaken(0,2);
+    sqlite3VdbeMemSetInt64(&aMem[pOp->p3], val);
+  }
+  goto check_for_interrupt;
+}
+
+/* Opcode: RowSetTest P1 P2 P3 P4
+** Synopsis: if r[P3] in rowset(P1) goto P2
+**
+** Register P3 is assumed to hold a 64-bit integer value. If register P1
+** contains a RowSet object and that RowSet object contains
+** the value held in P3, jump to register P2. Otherwise, insert the
+** integer in P3 into the RowSet and continue on to the
+** next opcode.
+**
+** The RowSet object is optimized for the case where successive sets
+** of integers, where each set contains no duplicates. Each set
+** of values is identified by a unique P4 value. The first set
+** must have P4==0, the final set P4=-1.  P4 must be either -1 or
+** non-negative.  For non-negative values of P4 only the lower 4
+** bits are significant.
+**
+** This allows optimizations: (a) when P4==0 there is no need to test
+** the rowset object for P3, as it is guaranteed not to contain it,
+** (b) when P4==-1 there is no need to insert the value, as it will
+** never be tested for, and (c) when a value that is part of set X is
+** inserted, there is no need to search to see if the same value was
+** previously inserted as part of set X (only if it was previously
+** inserted as part of some other set).
+*/
+case OP_RowSetTest: {                     /* jump, in1, in3 */
+  int iSet;
+  int exists;
+
+  pIn1 = &aMem[pOp->p1];
+  pIn3 = &aMem[pOp->p3];
+  iSet = pOp->p4.i;
+  assert( pIn3->flags&MEM_Int );
+
+  /* If there is anything other than a rowset object in memory cell P1,
+  ** delete it now and initialize P1 with an empty rowset
+  */
+  if( (pIn1->flags & MEM_RowSet)==0 ){
+    sqlite3VdbeMemSetRowSet(pIn1);
+    if( (pIn1->flags & MEM_RowSet)==0 ) goto no_mem;
+  }
+
+  assert( pOp->p4type==P4_INT32 );
+  assert( iSet==-1 || iSet>=0 );
+  if( iSet ){
+    exists = sqlite3RowSetTest(pIn1->u.pRowSet, iSet, pIn3->u.i);
+    VdbeBranchTaken(exists!=0,2);
+    if( exists ) goto jump_to_p2;
+  }
+  if( iSet>=0 ){
+    sqlite3RowSetInsert(pIn1->u.pRowSet, pIn3->u.i);
+  }
+  break;
+}
+
+
+#ifndef SQLITE_OMIT_TRIGGER
+
+/* Opcode: Program P1 P2 P3 P4 P5
+**
+** Execute the trigger program passed as P4 (type P4_SUBPROGRAM). 
+**
+** P1 contains the address of the memory cell that contains the first memory 
+** cell in an array of values used as arguments to the sub-program. P2 
+** contains the address to jump to if the sub-program throws an IGNORE 
+** exception using the RAISE() function. Register P3 contains the address 
+** of a memory cell in this (the parent) VM that is used to allocate the 
+** memory required by the sub-vdbe at runtime.
+**
+** P4 is a pointer to the VM containing the trigger program.
+**
+** If P5 is non-zero, then recursive program invocation is enabled.
+*/
+case OP_Program: {        /* jump */
+  int nMem;               /* Number of memory registers for sub-program */
+  int nByte;              /* Bytes of runtime space required for sub-program */
+  Mem *pRt;               /* Register to allocate runtime space */
+  Mem *pMem;              /* Used to iterate through memory cells */
+  Mem *pEnd;              /* Last memory cell in new array */
+  VdbeFrame *pFrame;      /* New vdbe frame to execute in */
+  SubProgram *pProgram;   /* Sub-program to execute */
+  void *t;                /* Token identifying trigger */
+
+  pProgram = pOp->p4.pProgram;
+  pRt = &aMem[pOp->p3];
+  assert( pProgram->nOp>0 );
+  
+  /* If the p5 flag is clear, then recursive invocation of triggers is 
+  ** disabled for backwards compatibility (p5 is set if this sub-program
+  ** is really a trigger, not a foreign key action, and the flag set
+  ** and cleared by the "PRAGMA recursive_triggers" command is clear).
+  ** 
+  ** It is recursive invocation of triggers, at the SQL level, that is 
+  ** disabled. In some cases a single trigger may generate more than one 
+  ** SubProgram (if the trigger may be executed with more than one different 
+  ** ON CONFLICT algorithm). SubProgram structures associated with a
+  ** single trigger all have the same value for the SubProgram.token 
+  ** variable.  */
+  if( pOp->p5 ){
+    t = pProgram->token;
+    for(pFrame=p->pFrame; pFrame && pFrame->token!=t; pFrame=pFrame->pParent);
+    if( pFrame ) break;
+  }
+
+  if( p->nFrame>=db->aLimit[SQLITE_LIMIT_TRIGGER_DEPTH] ){
+    rc = SQLITE_ERROR;
+    sqlite3VdbeError(p, "too many levels of trigger recursion");
+    goto abort_due_to_error;
+  }
+
+  /* Register pRt is used to store the memory required to save the state
+  ** of the current program, and the memory required at runtime to execute
+  ** the trigger program. If this trigger has been fired before, then pRt 
+  ** is already allocated. Otherwise, it must be initialized.  */
+  if( (pRt->flags&MEM_Frame)==0 ){
+    /* SubProgram.nMem is set to the number of memory cells used by the 
+    ** program stored in SubProgram.aOp. As well as these, one memory
+    ** cell is required for each cursor used by the program. Set local
+    ** variable nMem (and later, VdbeFrame.nChildMem) to this value.
+    */
+    nMem = pProgram->nMem + pProgram->nCsr;
+    assert( nMem>0 );
+    if( pProgram->nCsr==0 ) nMem++;
+    nByte = ROUND8(sizeof(VdbeFrame))
+              + nMem * sizeof(Mem)
+              + pProgram->nCsr * sizeof(VdbeCursor *);
+    pFrame = sqlite3DbMallocZero(db, nByte);
+    if( !pFrame ){
+      goto no_mem;
+    }
+    sqlite3VdbeMemRelease(pRt);
+    pRt->flags = MEM_Frame;
+    pRt->u.pFrame = pFrame;
+
+    pFrame->v = p;
+    pFrame->nChildMem = nMem;
+    pFrame->nChildCsr = pProgram->nCsr;
+    pFrame->pc = (int)(pOp - aOp);
+    pFrame->aMem = p->aMem;
+    pFrame->nMem = p->nMem;
+    pFrame->apCsr = p->apCsr;
+    pFrame->nCursor = p->nCursor;
+    pFrame->aOp = p->aOp;
+    pFrame->nOp = p->nOp;
+    pFrame->token = pProgram->token;
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+    pFrame->anExec = p->anExec;
+#endif
+
+    pEnd = &VdbeFrameMem(pFrame)[pFrame->nChildMem];
+    for(pMem=VdbeFrameMem(pFrame); pMem!=pEnd; pMem++){
+      pMem->flags = MEM_Undefined;
+      pMem->db = db;
+    }
+  }else{
+    pFrame = pRt->u.pFrame;
+    assert( pProgram->nMem+pProgram->nCsr==pFrame->nChildMem 
+        || (pProgram->nCsr==0 && pProgram->nMem+1==pFrame->nChildMem) );
+    assert( pProgram->nCsr==pFrame->nChildCsr );
+    assert( (int)(pOp - aOp)==pFrame->pc );
+  }
+
+  p->nFrame++;
+  pFrame->pParent = p->pFrame;
+  pFrame->lastRowid = lastRowid;
+  pFrame->nChange = p->nChange;
+  pFrame->nDbChange = p->db->nChange;
+  assert( pFrame->pAuxData==0 );
+  pFrame->pAuxData = p->pAuxData;
+  p->pAuxData = 0;
+  p->nChange = 0;
+  p->pFrame = pFrame;
+  p->aMem = aMem = VdbeFrameMem(pFrame);
+  p->nMem = pFrame->nChildMem;
+  p->nCursor = (u16)pFrame->nChildCsr;
+  p->apCsr = (VdbeCursor **)&aMem[p->nMem];
+  p->aOp = aOp = pProgram->aOp;
+  p->nOp = pProgram->nOp;
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+  p->anExec = 0;
+#endif
+  pOp = &aOp[-1];
+
+  break;
+}
+
+/* Opcode: Param P1 P2 * * *
+**
+** This opcode is only ever present in sub-programs called via the 
+** OP_Program instruction. Copy a value currently stored in a memory 
+** cell of the calling (parent) frame to cell P2 in the current frames 
+** address space. This is used by trigger programs to access the new.* 
+** and old.* values.
+**
+** The address of the cell in the parent frame is determined by adding
+** the value of the P1 argument to the value of the P1 argument to the
+** calling OP_Program instruction.
+*/
+case OP_Param: {           /* out2 */
+  VdbeFrame *pFrame;
+  Mem *pIn;
+  pOut = out2Prerelease(p, pOp);
+  pFrame = p->pFrame;
+  pIn = &pFrame->aMem[pOp->p1 + pFrame->aOp[pFrame->pc].p1];   
+  sqlite3VdbeMemShallowCopy(pOut, pIn, MEM_Ephem);
+  break;
+}
+
+#endif /* #ifndef SQLITE_OMIT_TRIGGER */
+
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+/* Opcode: FkCounter P1 P2 * * *
+** Synopsis: fkctr[P1]+=P2
+**
+** Increment a "constraint counter" by P2 (P2 may be negative or positive).
+** If P1 is non-zero, the database constraint counter is incremented 
+** (deferred foreign key constraints). Otherwise, if P1 is zero, the 
+** statement counter is incremented (immediate foreign key constraints).
+*/
+case OP_FkCounter: {
+  if( db->flags & SQLITE_DeferFKs ){
+    db->nDeferredImmCons += pOp->p2;
+  }else if( pOp->p1 ){
+    db->nDeferredCons += pOp->p2;
+  }else{
+    p->nFkConstraint += pOp->p2;
+  }
+  break;
+}
+
+/* Opcode: FkIfZero P1 P2 * * *
+** Synopsis: if fkctr[P1]==0 goto P2
+**
+** This opcode tests if a foreign key constraint-counter is currently zero.
+** If so, jump to instruction P2. Otherwise, fall through to the next 
+** instruction.
+**
+** If P1 is non-zero, then the jump is taken if the database constraint-counter
+** is zero (the one that counts deferred constraint violations). If P1 is
+** zero, the jump is taken if the statement constraint-counter is zero
+** (immediate foreign key constraint violations).
+*/
+case OP_FkIfZero: {         /* jump */
+  if( pOp->p1 ){
+    VdbeBranchTaken(db->nDeferredCons==0 && db->nDeferredImmCons==0, 2);
+    if( db->nDeferredCons==0 && db->nDeferredImmCons==0 ) goto jump_to_p2;
+  }else{
+    VdbeBranchTaken(p->nFkConstraint==0 && db->nDeferredImmCons==0, 2);
+    if( p->nFkConstraint==0 && db->nDeferredImmCons==0 ) goto jump_to_p2;
+  }
+  break;
+}
+#endif /* #ifndef SQLITE_OMIT_FOREIGN_KEY */
+
+#ifndef SQLITE_OMIT_AUTOINCREMENT
+/* Opcode: MemMax P1 P2 * * *
+** Synopsis: r[P1]=max(r[P1],r[P2])
+**
+** P1 is a register in the root frame of this VM (the root frame is
+** different from the current frame if this instruction is being executed
+** within a sub-program). Set the value of register P1 to the maximum of 
+** its current value and the value in register P2.
+**
+** This instruction throws an error if the memory cell is not initially
+** an integer.
+*/
+case OP_MemMax: {        /* in2 */
+  VdbeFrame *pFrame;
+  if( p->pFrame ){
+    for(pFrame=p->pFrame; pFrame->pParent; pFrame=pFrame->pParent);
+    pIn1 = &pFrame->aMem[pOp->p1];
+  }else{
+    pIn1 = &aMem[pOp->p1];
+  }
+  assert( memIsValid(pIn1) );
+  sqlite3VdbeMemIntegerify(pIn1);
+  pIn2 = &aMem[pOp->p2];
+  sqlite3VdbeMemIntegerify(pIn2);
+  if( pIn1->u.i<pIn2->u.i){
+    pIn1->u.i = pIn2->u.i;
+  }
+  break;
+}
+#endif /* SQLITE_OMIT_AUTOINCREMENT */
+
+/* Opcode: IfPos P1 P2 P3 * *
+** Synopsis: if r[P1]>0 then r[P1]-=P3, goto P2
+**
+** Register P1 must contain an integer.
+** If the value of register P1 is 1 or greater, subtract P3 from the
+** value in P1 and jump to P2.
+**
+** If the initial value of register P1 is less than 1, then the
+** value is unchanged and control passes through to the next instruction.
+*/
+case OP_IfPos: {        /* jump, in1 */
+  pIn1 = &aMem[pOp->p1];
+  assert( pIn1->flags&MEM_Int );
+  VdbeBranchTaken( pIn1->u.i>0, 2);
+  if( pIn1->u.i>0 ){
+    pIn1->u.i -= pOp->p3;
+    goto jump_to_p2;
+  }
+  break;
+}
+
+/* Opcode: OffsetLimit P1 P2 P3 * *
+** Synopsis: if r[P1]>0 then r[P2]=r[P1]+max(0,r[P3]) else r[P2]=(-1)
+**
+** This opcode performs a commonly used computation associated with
+** LIMIT and OFFSET process.  r[P1] holds the limit counter.  r[P3]
+** holds the offset counter.  The opcode computes the combined value
+** of the LIMIT and OFFSET and stores that value in r[P2].  The r[P2]
+** value computed is the total number of rows that will need to be
+** visited in order to complete the query.
+**
+** If r[P3] is zero or negative, that means there is no OFFSET
+** and r[P2] is set to be the value of the LIMIT, r[P1].
+**
+** if r[P1] is zero or negative, that means there is no LIMIT
+** and r[P2] is set to -1. 
+**
+** Otherwise, r[P2] is set to the sum of r[P1] and r[P3].
+*/
+case OP_OffsetLimit: {    /* in1, out2, in3 */
+  pIn1 = &aMem[pOp->p1];
+  pIn3 = &aMem[pOp->p3];
+  pOut = out2Prerelease(p, pOp);
+  assert( pIn1->flags & MEM_Int );
+  assert( pIn3->flags & MEM_Int );
+  pOut->u.i = pIn1->u.i<=0 ? -1 : pIn1->u.i+(pIn3->u.i>0?pIn3->u.i:0);
+  break;
+}
+
+/* Opcode: IfNotZero P1 P2 P3 * *
+** Synopsis: if r[P1]!=0 then r[P1]-=P3, goto P2
+**
+** Register P1 must contain an integer.  If the content of register P1 is
+** initially nonzero, then subtract P3 from the value in register P1 and
+** jump to P2.  If register P1 is initially zero, leave it unchanged
+** and fall through.
+*/
+case OP_IfNotZero: {        /* jump, in1 */
+  pIn1 = &aMem[pOp->p1];
+  assert( pIn1->flags&MEM_Int );
+  VdbeBranchTaken(pIn1->u.i<0, 2);
+  if( pIn1->u.i ){
+     pIn1->u.i -= pOp->p3;
+     goto jump_to_p2;
+  }
+  break;
+}
+
+/* Opcode: DecrJumpZero P1 P2 * * *
+** Synopsis: if (--r[P1])==0 goto P2
+**
+** Register P1 must hold an integer.  Decrement the value in register P1
+** then jump to P2 if the new value is exactly zero.
+*/
+case OP_DecrJumpZero: {      /* jump, in1 */
+  pIn1 = &aMem[pOp->p1];
+  assert( pIn1->flags&MEM_Int );
+  pIn1->u.i--;
+  VdbeBranchTaken(pIn1->u.i==0, 2);
+  if( pIn1->u.i==0 ) goto jump_to_p2;
+  break;
+}
+
+
+/* Opcode: AggStep0 * P2 P3 P4 P5
+** Synopsis: accum=r[P3] step(r[P2@P5])
+**
+** Execute the step function for an aggregate.  The
+** function has P5 arguments.   P4 is a pointer to the FuncDef
+** structure that specifies the function.  Register P3 is the
+** accumulator.
+**
+** The P5 arguments are taken from register P2 and its
+** successors.
+*/
+/* Opcode: AggStep * P2 P3 P4 P5
+** Synopsis: accum=r[P3] step(r[P2@P5])
+**
+** Execute the step function for an aggregate.  The
+** function has P5 arguments.   P4 is a pointer to an sqlite3_context
+** object that is used to run the function.  Register P3 is
+** as the accumulator.
+**
+** The P5 arguments are taken from register P2 and its
+** successors.
+**
+** This opcode is initially coded as OP_AggStep0.  On first evaluation,
+** the FuncDef stored in P4 is converted into an sqlite3_context and
+** the opcode is changed.  In this way, the initialization of the
+** sqlite3_context only happens once, instead of on each call to the
+** step function.
+*/
+case OP_AggStep0: {
+  int n;
+  sqlite3_context *pCtx;
+
+  assert( pOp->p4type==P4_FUNCDEF );
+  n = pOp->p5;
+  assert( pOp->p3>0 && pOp->p3<=(p->nMem+1 - p->nCursor) );
+  assert( n==0 || (pOp->p2>0 && pOp->p2+n<=(p->nMem+1 - p->nCursor)+1) );
+  assert( pOp->p3<pOp->p2 || pOp->p3>=pOp->p2+n );
+  pCtx = sqlite3DbMallocRawNN(db, sizeof(*pCtx) + (n-1)*sizeof(sqlite3_value*));
+  if( pCtx==0 ) goto no_mem;
+  pCtx->pMem = 0;
+  pCtx->pFunc = pOp->p4.pFunc;
+  pCtx->iOp = (int)(pOp - aOp);
+  pCtx->pVdbe = p;
+  pCtx->argc = n;
+  pOp->p4type = P4_FUNCCTX;
+  pOp->p4.pCtx = pCtx;
+  pOp->opcode = OP_AggStep;
+  /* Fall through into OP_AggStep */
+}
+case OP_AggStep: {
+  int i;
+  sqlite3_context *pCtx;
+  Mem *pMem;
+  Mem t;
+
+  assert( pOp->p4type==P4_FUNCCTX );
+  pCtx = pOp->p4.pCtx;
+  pMem = &aMem[pOp->p3];
+
+  /* If this function is inside of a trigger, the register array in aMem[]
+  ** might change from one evaluation to the next.  The next block of code
+  ** checks to see if the register array has changed, and if so it
+  ** reinitializes the relavant parts of the sqlite3_context object */
+  if( pCtx->pMem != pMem ){
+    pCtx->pMem = pMem;
+    for(i=pCtx->argc-1; i>=0; i--) pCtx->argv[i] = &aMem[pOp->p2+i];
+  }
+
+#ifdef SQLITE_DEBUG
+  for(i=0; i<pCtx->argc; i++){
+    assert( memIsValid(pCtx->argv[i]) );
+    REGISTER_TRACE(pOp->p2+i, pCtx->argv[i]);
+  }
+#endif
+
+  pMem->n++;
+  sqlite3VdbeMemInit(&t, db, MEM_Null);
+  pCtx->pOut = &t;
+  pCtx->fErrorOrAux = 0;
+  pCtx->skipFlag = 0;
+  (pCtx->pFunc->xSFunc)(pCtx,pCtx->argc,pCtx->argv); /* IMP: R-24505-23230 */
+  if( pCtx->fErrorOrAux ){
+    if( pCtx->isError ){
+      sqlite3VdbeError(p, "%s", sqlite3_value_text(&t));
+      rc = pCtx->isError;
+    }
+    sqlite3VdbeMemRelease(&t);
+    if( rc ) goto abort_due_to_error;
+  }else{
+    assert( t.flags==MEM_Null );
+  }
+  if( pCtx->skipFlag ){
+    assert( pOp[-1].opcode==OP_CollSeq );
+    i = pOp[-1].p1;
+    if( i ) sqlite3VdbeMemSetInt64(&aMem[i], 1);
+  }
+  break;
+}
+
+/* Opcode: AggFinal P1 P2 * P4 *
+** Synopsis: accum=r[P1] N=P2
+**
+** Execute the finalizer function for an aggregate.  P1 is
+** the memory location that is the accumulator for the aggregate.
+**
+** P2 is the number of arguments that the step function takes and
+** P4 is a pointer to the FuncDef for this function.  The P2
+** argument is not used by this opcode.  It is only there to disambiguate
+** functions that can take varying numbers of arguments.  The
+** P4 argument is only needed for the degenerate case where
+** the step function was not previously called.
+*/
+case OP_AggFinal: {
+  Mem *pMem;
+  assert( pOp->p1>0 && pOp->p1<=(p->nMem+1 - p->nCursor) );
+  pMem = &aMem[pOp->p1];
+  assert( (pMem->flags & ~(MEM_Null|MEM_Agg))==0 );
+  rc = sqlite3VdbeMemFinalize(pMem, pOp->p4.pFunc);
+  if( rc ){
+    sqlite3VdbeError(p, "%s", sqlite3_value_text(pMem));
+    goto abort_due_to_error;
+  }
+  sqlite3VdbeChangeEncoding(pMem, encoding);
+  UPDATE_MAX_BLOBSIZE(pMem);
+  if( sqlite3VdbeMemTooBig(pMem) ){
+    goto too_big;
+  }
+  break;
+}
+
+#ifndef SQLITE_OMIT_WAL
+/* Opcode: Checkpoint P1 P2 P3 * *
+**
+** Checkpoint database P1. This is a no-op if P1 is not currently in
+** WAL mode. Parameter P2 is one of SQLITE_CHECKPOINT_PASSIVE, FULL,
+** RESTART, or TRUNCATE.  Write 1 or 0 into mem[P3] if the checkpoint returns
+** SQLITE_BUSY or not, respectively.  Write the number of pages in the
+** WAL after the checkpoint into mem[P3+1] and the number of pages
+** in the WAL that have been checkpointed after the checkpoint
+** completes into mem[P3+2].  However on an error, mem[P3+1] and
+** mem[P3+2] are initialized to -1.
+*/
+case OP_Checkpoint: {
+  int i;                          /* Loop counter */
+  int aRes[3];                    /* Results */
+  Mem *pMem;                      /* Write results here */
+
+  assert( p->readOnly==0 );
+  aRes[0] = 0;
+  aRes[1] = aRes[2] = -1;
+  assert( pOp->p2==SQLITE_CHECKPOINT_PASSIVE
+       || pOp->p2==SQLITE_CHECKPOINT_FULL
+       || pOp->p2==SQLITE_CHECKPOINT_RESTART
+       || pOp->p2==SQLITE_CHECKPOINT_TRUNCATE
+  );
+  rc = sqlite3Checkpoint(db, pOp->p1, pOp->p2, &aRes[1], &aRes[2]);
+  if( rc ){
+    if( rc!=SQLITE_BUSY ) goto abort_due_to_error;
+    rc = SQLITE_OK;
+    aRes[0] = 1;
+  }
+  for(i=0, pMem = &aMem[pOp->p3]; i<3; i++, pMem++){
+    sqlite3VdbeMemSetInt64(pMem, (i64)aRes[i]);
+  }    
+  break;
+};  
+#endif
+
+#ifndef SQLITE_OMIT_PRAGMA
+/* Opcode: JournalMode P1 P2 P3 * *
+**
+** Change the journal mode of database P1 to P3. P3 must be one of the
+** PAGER_JOURNALMODE_XXX values. If changing between the various rollback
+** modes (delete, truncate, persist, off and memory), this is a simple
+** operation. No IO is required.
+**
+** If changing into or out of WAL mode the procedure is more complicated.
+**
+** Write a string containing the final journal-mode to register P2.
+*/
+case OP_JournalMode: {    /* out2 */
+  Btree *pBt;                     /* Btree to change journal mode of */
+  Pager *pPager;                  /* Pager associated with pBt */
+  int eNew;                       /* New journal mode */
+  int eOld;                       /* The old journal mode */
+#ifndef SQLITE_OMIT_WAL
+  const char *zFilename;          /* Name of database file for pPager */
+#endif
+
+  pOut = out2Prerelease(p, pOp);
+  eNew = pOp->p3;
+  assert( eNew==PAGER_JOURNALMODE_DELETE 
+       || eNew==PAGER_JOURNALMODE_TRUNCATE 
+       || eNew==PAGER_JOURNALMODE_PERSIST 
+       || eNew==PAGER_JOURNALMODE_OFF
+       || eNew==PAGER_JOURNALMODE_MEMORY
+       || eNew==PAGER_JOURNALMODE_WAL
+       || eNew==PAGER_JOURNALMODE_QUERY
+  );
+  assert( pOp->p1>=0 && pOp->p1<db->nDb );
+  assert( p->readOnly==0 );
+
+  pBt = db->aDb[pOp->p1].pBt;
+  pPager = sqlite3BtreePager(pBt);
+  eOld = sqlite3PagerGetJournalMode(pPager);
+  if( eNew==PAGER_JOURNALMODE_QUERY ) eNew = eOld;
+  if( !sqlite3PagerOkToChangeJournalMode(pPager) ) eNew = eOld;
+
+#ifndef SQLITE_OMIT_WAL
+  zFilename = sqlite3PagerFilename(pPager, 1);
+
+  /* Do not allow a transition to journal_mode=WAL for a database
+  ** in temporary storage or if the VFS does not support shared memory 
+  */
+  if( eNew==PAGER_JOURNALMODE_WAL
+   && (sqlite3Strlen30(zFilename)==0           /* Temp file */
+       || !sqlite3PagerWalSupported(pPager))   /* No shared-memory support */
+  ){
+    eNew = eOld;
+  }
+
+  if( (eNew!=eOld)
+   && (eOld==PAGER_JOURNALMODE_WAL || eNew==PAGER_JOURNALMODE_WAL)
+  ){
+    if( !db->autoCommit || db->nVdbeRead>1 ){
+      rc = SQLITE_ERROR;
+      sqlite3VdbeError(p,
+          "cannot change %s wal mode from within a transaction",
+          (eNew==PAGER_JOURNALMODE_WAL ? "into" : "out of")
+      );
+      goto abort_due_to_error;
+    }else{
+ 
+      if( eOld==PAGER_JOURNALMODE_WAL ){
+        /* If leaving WAL mode, close the log file. If successful, the call
+        ** to PagerCloseWal() checkpoints and deletes the write-ahead-log 
+        ** file. An EXCLUSIVE lock may still be held on the database file 
+        ** after a successful return. 
+        */
+        rc = sqlite3PagerCloseWal(pPager);
+        if( rc==SQLITE_OK ){
+          sqlite3PagerSetJournalMode(pPager, eNew);
+        }
+      }else if( eOld==PAGER_JOURNALMODE_MEMORY ){
+        /* Cannot transition directly from MEMORY to WAL.  Use mode OFF
+        ** as an intermediate */
+        sqlite3PagerSetJournalMode(pPager, PAGER_JOURNALMODE_OFF);
+      }
+  
+      /* Open a transaction on the database file. Regardless of the journal
+      ** mode, this transaction always uses a rollback journal.
+      */
+      assert( sqlite3BtreeIsInTrans(pBt)==0 );
+      if( rc==SQLITE_OK ){
+        rc = sqlite3BtreeSetVersion(pBt, (eNew==PAGER_JOURNALMODE_WAL ? 2 : 1));
+      }
+    }
+  }
+#endif /* ifndef SQLITE_OMIT_WAL */
+
+  if( rc ) eNew = eOld;
+  eNew = sqlite3PagerSetJournalMode(pPager, eNew);
+
+  pOut->flags = MEM_Str|MEM_Static|MEM_Term;
+  pOut->z = (char *)sqlite3JournalModename(eNew);
+  pOut->n = sqlite3Strlen30(pOut->z);
+  pOut->enc = SQLITE_UTF8;
+  sqlite3VdbeChangeEncoding(pOut, encoding);
+  if( rc ) goto abort_due_to_error;
+  break;
+};
+#endif /* SQLITE_OMIT_PRAGMA */
+
+#if !defined(SQLITE_OMIT_VACUUM) && !defined(SQLITE_OMIT_ATTACH)
+/* Opcode: Vacuum P1 * * * *
+**
+** Vacuum the entire database P1.  P1 is 0 for "main", and 2 or more
+** for an attached database.  The "temp" database may not be vacuumed.
+*/
+case OP_Vacuum: {
+  assert( p->readOnly==0 );
+  rc = sqlite3RunVacuum(&p->zErrMsg, db, pOp->p1);
+  if( rc ) goto abort_due_to_error;
+  break;
+}
+#endif
+
+#if !defined(SQLITE_OMIT_AUTOVACUUM)
+/* Opcode: IncrVacuum P1 P2 * * *
+**
+** Perform a single step of the incremental vacuum procedure on
+** the P1 database. If the vacuum has finished, jump to instruction
+** P2. Otherwise, fall through to the next instruction.
+*/
+case OP_IncrVacuum: {        /* jump */
+  Btree *pBt;
+
+  assert( pOp->p1>=0 && pOp->p1<db->nDb );
+  assert( DbMaskTest(p->btreeMask, pOp->p1) );
+  assert( p->readOnly==0 );
+  pBt = db->aDb[pOp->p1].pBt;
+  rc = sqlite3BtreeIncrVacuum(pBt);
+  VdbeBranchTaken(rc==SQLITE_DONE,2);
+  if( rc ){
+    if( rc!=SQLITE_DONE ) goto abort_due_to_error;
+    rc = SQLITE_OK;
+    goto jump_to_p2;
+  }
+  break;
+}
+#endif
+
+/* Opcode: Expire P1 * * * *
+**
+** Cause precompiled statements to expire.  When an expired statement
+** is executed using sqlite3_step() it will either automatically
+** reprepare itself (if it was originally created using sqlite3_prepare_v2())
+** or it will fail with SQLITE_SCHEMA.
+** 
+** If P1 is 0, then all SQL statements become expired. If P1 is non-zero,
+** then only the currently executing statement is expired.
+*/
+case OP_Expire: {
+  if( !pOp->p1 ){
+    sqlite3ExpirePreparedStatements(db);
+  }else{
+    p->expired = 1;
+  }
+  break;
+}
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+/* Opcode: TableLock P1 P2 P3 P4 *
+** Synopsis: iDb=P1 root=P2 write=P3
+**
+** Obtain a lock on a particular table. This instruction is only used when
+** the shared-cache feature is enabled. 
+**
+** P1 is the index of the database in sqlite3.aDb[] of the database
+** on which the lock is acquired.  A readlock is obtained if P3==0 or
+** a write lock if P3==1.
+**
+** P2 contains the root-page of the table to lock.
+**
+** P4 contains a pointer to the name of the table being locked. This is only
+** used to generate an error message if the lock cannot be obtained.
+*/
+case OP_TableLock: {
+  u8 isWriteLock = (u8)pOp->p3;
+  if( isWriteLock || 0==(db->flags&SQLITE_ReadUncommitted) ){
+    int p1 = pOp->p1; 
+    assert( p1>=0 && p1<db->nDb );
+    assert( DbMaskTest(p->btreeMask, p1) );
+    assert( isWriteLock==0 || isWriteLock==1 );
+    rc = sqlite3BtreeLockTable(db->aDb[p1].pBt, pOp->p2, isWriteLock);
+    if( rc ){
+      if( (rc&0xFF)==SQLITE_LOCKED ){
+        const char *z = pOp->p4.z;
+        sqlite3VdbeError(p, "database table is locked: %s", z);
+      }
+      goto abort_due_to_error;
+    }
+  }
+  break;
+}
+#endif /* SQLITE_OMIT_SHARED_CACHE */
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/* Opcode: VBegin * * * P4 *
+**
+** P4 may be a pointer to an sqlite3_vtab structure. If so, call the 
+** xBegin method for that table.
+**
+** Also, whether or not P4 is set, check that this is not being called from
+** within a callback to a virtual table xSync() method. If it is, the error
+** code will be set to SQLITE_LOCKED.
+*/
+case OP_VBegin: {
+  VTable *pVTab;
+  pVTab = pOp->p4.pVtab;
+  rc = sqlite3VtabBegin(db, pVTab);
+  if( pVTab ) sqlite3VtabImportErrmsg(p, pVTab->pVtab);
+  if( rc ) goto abort_due_to_error;
+  break;
+}
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/* Opcode: VCreate P1 P2 * * *
+**
+** P2 is a register that holds the name of a virtual table in database 
+** P1. Call the xCreate method for that table.
+*/
+case OP_VCreate: {
+  Mem sMem;          /* For storing the record being decoded */
+  const char *zTab;  /* Name of the virtual table */
+
+  memset(&sMem, 0, sizeof(sMem));
+  sMem.db = db;
+  /* Because P2 is always a static string, it is impossible for the
+  ** sqlite3VdbeMemCopy() to fail */
+  assert( (aMem[pOp->p2].flags & MEM_Str)!=0 );
+  assert( (aMem[pOp->p2].flags & MEM_Static)!=0 );
+  rc = sqlite3VdbeMemCopy(&sMem, &aMem[pOp->p2]);
+  assert( rc==SQLITE_OK );
+  zTab = (const char*)sqlite3_value_text(&sMem);
+  assert( zTab || db->mallocFailed );
+  if( zTab ){
+    rc = sqlite3VtabCallCreate(db, pOp->p1, zTab, &p->zErrMsg);
+  }
+  sqlite3VdbeMemRelease(&sMem);
+  if( rc ) goto abort_due_to_error;
+  break;
+}
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/* Opcode: VDestroy P1 * * P4 *
+**
+** P4 is the name of a virtual table in database P1.  Call the xDestroy method
+** of that table.
+*/
+case OP_VDestroy: {
+  db->nVDestroy++;
+  rc = sqlite3VtabCallDestroy(db, pOp->p1, pOp->p4.z);
+  db->nVDestroy--;
+  if( rc ) goto abort_due_to_error;
+  break;
+}
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/* Opcode: VOpen P1 * * P4 *
+**
+** P4 is a pointer to a virtual table object, an sqlite3_vtab structure.
+** P1 is a cursor number.  This opcode opens a cursor to the virtual
+** table and stores that cursor in P1.
+*/
+case OP_VOpen: {
+  VdbeCursor *pCur;
+  sqlite3_vtab_cursor *pVCur;
+  sqlite3_vtab *pVtab;
+  const sqlite3_module *pModule;
+
+  assert( p->bIsReader );
+  pCur = 0;
+  pVCur = 0;
+  pVtab = pOp->p4.pVtab->pVtab;
+  if( pVtab==0 || NEVER(pVtab->pModule==0) ){
+    rc = SQLITE_LOCKED;
+    goto abort_due_to_error;
+  }
+  pModule = pVtab->pModule;
+  rc = pModule->xOpen(pVtab, &pVCur);
+  sqlite3VtabImportErrmsg(p, pVtab);
+  if( rc ) goto abort_due_to_error;
+
+  /* Initialize sqlite3_vtab_cursor base class */
+  pVCur->pVtab = pVtab;
+
+  /* Initialize vdbe cursor object */
+  pCur = allocateCursor(p, pOp->p1, 0, -1, CURTYPE_VTAB);
+  if( pCur ){
+    pCur->uc.pVCur = pVCur;
+    pVtab->nRef++;
+  }else{
+    assert( db->mallocFailed );
+    pModule->xClose(pVCur);
+    goto no_mem;
+  }
+  break;
+}
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/* Opcode: VFilter P1 P2 P3 P4 *
+** Synopsis: iplan=r[P3] zplan='P4'
+**
+** P1 is a cursor opened using VOpen.  P2 is an address to jump to if
+** the filtered result set is empty.
+**
+** P4 is either NULL or a string that was generated by the xBestIndex
+** method of the module.  The interpretation of the P4 string is left
+** to the module implementation.
+**
+** This opcode invokes the xFilter method on the virtual table specified
+** by P1.  The integer query plan parameter to xFilter is stored in register
+** P3. Register P3+1 stores the argc parameter to be passed to the
+** xFilter method. Registers P3+2..P3+1+argc are the argc
+** additional parameters which are passed to
+** xFilter as argv. Register P3+2 becomes argv[0] when passed to xFilter.
+**
+** A jump is made to P2 if the result set after filtering would be empty.
+*/
+case OP_VFilter: {   /* jump */
+  int nArg;
+  int iQuery;
+  const sqlite3_module *pModule;
+  Mem *pQuery;
+  Mem *pArgc;
+  sqlite3_vtab_cursor *pVCur;
+  sqlite3_vtab *pVtab;
+  VdbeCursor *pCur;
+  int res;
+  int i;
+  Mem **apArg;
+
+  pQuery = &aMem[pOp->p3];
+  pArgc = &pQuery[1];
+  pCur = p->apCsr[pOp->p1];
+  assert( memIsValid(pQuery) );
+  REGISTER_TRACE(pOp->p3, pQuery);
+  assert( pCur->eCurType==CURTYPE_VTAB );
+  pVCur = pCur->uc.pVCur;
+  pVtab = pVCur->pVtab;
+  pModule = pVtab->pModule;
+
+  /* Grab the index number and argc parameters */
+  assert( (pQuery->flags&MEM_Int)!=0 && pArgc->flags==MEM_Int );
+  nArg = (int)pArgc->u.i;
+  iQuery = (int)pQuery->u.i;
+
+  /* Invoke the xFilter method */
+  res = 0;
+  apArg = p->apArg;
+  for(i = 0; i<nArg; i++){
+    apArg[i] = &pArgc[i+1];
+  }
+  rc = pModule->xFilter(pVCur, iQuery, pOp->p4.z, nArg, apArg);
+  sqlite3VtabImportErrmsg(p, pVtab);
+  if( rc ) goto abort_due_to_error;
+  res = pModule->xEof(pVCur);
+  pCur->nullRow = 0;
+  VdbeBranchTaken(res!=0,2);
+  if( res ) goto jump_to_p2;
+  break;
+}
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/* Opcode: VColumn P1 P2 P3 * *
+** Synopsis: r[P3]=vcolumn(P2)
+**
+** Store the value of the P2-th column of
+** the row of the virtual-table that the 
+** P1 cursor is pointing to into register P3.
+*/
+case OP_VColumn: {
+  sqlite3_vtab *pVtab;
+  const sqlite3_module *pModule;
+  Mem *pDest;
+  sqlite3_context sContext;
+
+  VdbeCursor *pCur = p->apCsr[pOp->p1];
+  assert( pCur->eCurType==CURTYPE_VTAB );
+  assert( pOp->p3>0 && pOp->p3<=(p->nMem+1 - p->nCursor) );
+  pDest = &aMem[pOp->p3];
+  memAboutToChange(p, pDest);
+  if( pCur->nullRow ){
+    sqlite3VdbeMemSetNull(pDest);
+    break;
+  }
+  pVtab = pCur->uc.pVCur->pVtab;
+  pModule = pVtab->pModule;
+  assert( pModule->xColumn );
+  memset(&sContext, 0, sizeof(sContext));
+  sContext.pOut = pDest;
+  MemSetTypeFlag(pDest, MEM_Null);
+  rc = pModule->xColumn(pCur->uc.pVCur, &sContext, pOp->p2);
+  sqlite3VtabImportErrmsg(p, pVtab);
+  if( sContext.isError ){
+    rc = sContext.isError;
+  }
+  sqlite3VdbeChangeEncoding(pDest, encoding);
+  REGISTER_TRACE(pOp->p3, pDest);
+  UPDATE_MAX_BLOBSIZE(pDest);
+
+  if( sqlite3VdbeMemTooBig(pDest) ){
+    goto too_big;
+  }
+  if( rc ) goto abort_due_to_error;
+  break;
+}
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/* Opcode: VNext P1 P2 * * *
+**
+** Advance virtual table P1 to the next row in its result set and
+** jump to instruction P2.  Or, if the virtual table has reached
+** the end of its result set, then fall through to the next instruction.
+*/
+case OP_VNext: {   /* jump */
+  sqlite3_vtab *pVtab;
+  const sqlite3_module *pModule;
+  int res;
+  VdbeCursor *pCur;
+
+  res = 0;
+  pCur = p->apCsr[pOp->p1];
+  assert( pCur->eCurType==CURTYPE_VTAB );
+  if( pCur->nullRow ){
+    break;
+  }
+  pVtab = pCur->uc.pVCur->pVtab;
+  pModule = pVtab->pModule;
+  assert( pModule->xNext );
+
+  /* Invoke the xNext() method of the module. There is no way for the
+  ** underlying implementation to return an error if one occurs during
+  ** xNext(). Instead, if an error occurs, true is returned (indicating that 
+  ** data is available) and the error code returned when xColumn or
+  ** some other method is next invoked on the save virtual table cursor.
+  */
+  rc = pModule->xNext(pCur->uc.pVCur);
+  sqlite3VtabImportErrmsg(p, pVtab);
+  if( rc ) goto abort_due_to_error;
+  res = pModule->xEof(pCur->uc.pVCur);
+  VdbeBranchTaken(!res,2);
+  if( !res ){
+    /* If there is data, jump to P2 */
+    goto jump_to_p2_and_check_for_interrupt;
+  }
+  goto check_for_interrupt;
+}
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/* Opcode: VRename P1 * * P4 *
+**
+** P4 is a pointer to a virtual table object, an sqlite3_vtab structure.
+** This opcode invokes the corresponding xRename method. The value
+** in register P1 is passed as the zName argument to the xRename method.
+*/
+case OP_VRename: {
+  sqlite3_vtab *pVtab;
+  Mem *pName;
+
+  pVtab = pOp->p4.pVtab->pVtab;
+  pName = &aMem[pOp->p1];
+  assert( pVtab->pModule->xRename );
+  assert( memIsValid(pName) );
+  assert( p->readOnly==0 );
+  REGISTER_TRACE(pOp->p1, pName);
+  assert( pName->flags & MEM_Str );
+  testcase( pName->enc==SQLITE_UTF8 );
+  testcase( pName->enc==SQLITE_UTF16BE );
+  testcase( pName->enc==SQLITE_UTF16LE );
+  rc = sqlite3VdbeChangeEncoding(pName, SQLITE_UTF8);
+  if( rc ) goto abort_due_to_error;
+  rc = pVtab->pModule->xRename(pVtab, pName->z);
+  sqlite3VtabImportErrmsg(p, pVtab);
+  p->expired = 0;
+  if( rc ) goto abort_due_to_error;
+  break;
+}
+#endif
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/* Opcode: VUpdate P1 P2 P3 P4 P5
+** Synopsis: data=r[P3@P2]
+**
+** P4 is a pointer to a virtual table object, an sqlite3_vtab structure.
+** This opcode invokes the corresponding xUpdate method. P2 values
+** are contiguous memory cells starting at P3 to pass to the xUpdate 
+** invocation. The value in register (P3+P2-1) corresponds to the 
+** p2th element of the argv array passed to xUpdate.
+**
+** The xUpdate method will do a DELETE or an INSERT or both.
+** The argv[0] element (which corresponds to memory cell P3)
+** is the rowid of a row to delete.  If argv[0] is NULL then no 
+** deletion occurs.  The argv[1] element is the rowid of the new 
+** row.  This can be NULL to have the virtual table select the new 
+** rowid for itself.  The subsequent elements in the array are 
+** the values of columns in the new row.
+**
+** If P2==1 then no insert is performed.  argv[0] is the rowid of
+** a row to delete.
+**
+** P1 is a boolean flag. If it is set to true and the xUpdate call
+** is successful, then the value returned by sqlite3_last_insert_rowid() 
+** is set to the value of the rowid for the row just inserted.
+**
+** P5 is the error actions (OE_Replace, OE_Fail, OE_Ignore, etc) to
+** apply in the case of a constraint failure on an insert or update.
+*/
+case OP_VUpdate: {
+  sqlite3_vtab *pVtab;
+  const sqlite3_module *pModule;
+  int nArg;
+  int i;
+  sqlite_int64 rowid;
+  Mem **apArg;
+  Mem *pX;
+
+  assert( pOp->p2==1        || pOp->p5==OE_Fail   || pOp->p5==OE_Rollback 
+       || pOp->p5==OE_Abort || pOp->p5==OE_Ignore || pOp->p5==OE_Replace
+  );
+  assert( p->readOnly==0 );
+  pVtab = pOp->p4.pVtab->pVtab;
+  if( pVtab==0 || NEVER(pVtab->pModule==0) ){
+    rc = SQLITE_LOCKED;
+    goto abort_due_to_error;
+  }
+  pModule = pVtab->pModule;
+  nArg = pOp->p2;
+  assert( pOp->p4type==P4_VTAB );
+  if( ALWAYS(pModule->xUpdate) ){
+    u8 vtabOnConflict = db->vtabOnConflict;
+    apArg = p->apArg;
+    pX = &aMem[pOp->p3];
+    for(i=0; i<nArg; i++){
+      assert( memIsValid(pX) );
+      memAboutToChange(p, pX);
+      apArg[i] = pX;
+      pX++;
+    }
+    db->vtabOnConflict = pOp->p5;
+    rc = pModule->xUpdate(pVtab, nArg, apArg, &rowid);
+    db->vtabOnConflict = vtabOnConflict;
+    sqlite3VtabImportErrmsg(p, pVtab);
+    if( rc==SQLITE_OK && pOp->p1 ){
+      assert( nArg>1 && apArg[0] && (apArg[0]->flags&MEM_Null) );
+      db->lastRowid = lastRowid = rowid;
+    }
+    if( (rc&0xff)==SQLITE_CONSTRAINT && pOp->p4.pVtab->bConstraint ){
+      if( pOp->p5==OE_Ignore ){
+        rc = SQLITE_OK;
+      }else{
+        p->errorAction = ((pOp->p5==OE_Replace) ? OE_Abort : pOp->p5);
+      }
+    }else{
+      p->nChange++;
+    }
+    if( rc ) goto abort_due_to_error;
+  }
+  break;
+}
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+#ifndef  SQLITE_OMIT_PAGER_PRAGMAS
+/* Opcode: Pagecount P1 P2 * * *
+**
+** Write the current number of pages in database P1 to memory cell P2.
+*/
+case OP_Pagecount: {            /* out2 */
+  pOut = out2Prerelease(p, pOp);
+  pOut->u.i = sqlite3BtreeLastPage(db->aDb[pOp->p1].pBt);
+  break;
+}
+#endif
+
+
+#ifndef  SQLITE_OMIT_PAGER_PRAGMAS
+/* Opcode: MaxPgcnt P1 P2 P3 * *
+**
+** Try to set the maximum page count for database P1 to the value in P3.
+** Do not let the maximum page count fall below the current page count and
+** do not change the maximum page count value if P3==0.
+**
+** Store the maximum page count after the change in register P2.
+*/
+case OP_MaxPgcnt: {            /* out2 */
+  unsigned int newMax;
+  Btree *pBt;
+
+  pOut = out2Prerelease(p, pOp);
+  pBt = db->aDb[pOp->p1].pBt;
+  newMax = 0;
+  if( pOp->p3 ){
+    newMax = sqlite3BtreeLastPage(pBt);
+    if( newMax < (unsigned)pOp->p3 ) newMax = (unsigned)pOp->p3;
+  }
+  pOut->u.i = sqlite3BtreeMaxPageCount(pBt, newMax);
+  break;
+}
+#endif
+
+
+/* Opcode: Init P1 P2 * P4 *
+** Synopsis: Start at P2
+**
+** Programs contain a single instance of this opcode as the very first
+** opcode.
+**
+** If tracing is enabled (by the sqlite3_trace()) interface, then
+** the UTF-8 string contained in P4 is emitted on the trace callback.
+** Or if P4 is blank, use the string returned by sqlite3_sql().
+**
+** If P2 is not zero, jump to instruction P2.
+**
+** Increment the value of P1 so that OP_Once opcodes will jump the
+** first time they are evaluated for this run.
+*/
+case OP_Init: {          /* jump */
+  char *zTrace;
+  int i;
+
+  /* If the P4 argument is not NULL, then it must be an SQL comment string.
+  ** The "--" string is broken up to prevent false-positives with srcck1.c.
+  **
+  ** This assert() provides evidence for:
+  ** EVIDENCE-OF: R-50676-09860 The callback can compute the same text that
+  ** would have been returned by the legacy sqlite3_trace() interface by
+  ** using the X argument when X begins with "--" and invoking
+  ** sqlite3_expanded_sql(P) otherwise.
+  */
+  assert( pOp->p4.z==0 || strncmp(pOp->p4.z, "-" "- ", 3)==0 );
+  assert( pOp==p->aOp );  /* Always instruction 0 */
+
+#ifndef SQLITE_OMIT_TRACE
+  if( (db->mTrace & (SQLITE_TRACE_STMT|SQLITE_TRACE_LEGACY))!=0
+   && !p->doingRerun
+   && (zTrace = (pOp->p4.z ? pOp->p4.z : p->zSql))!=0
+  ){
+#ifndef SQLITE_OMIT_DEPRECATED
+    if( db->mTrace & SQLITE_TRACE_LEGACY ){
+      void (*x)(void*,const char*) = (void(*)(void*,const char*))db->xTrace;
+      char *z = sqlite3VdbeExpandSql(p, zTrace);
+      x(db->pTraceArg, z);
+      sqlite3_free(z);
+    }else
+#endif
+    {
+      (void)db->xTrace(SQLITE_TRACE_STMT, db->pTraceArg, p, zTrace);
+    }
+  }
+#ifdef SQLITE_USE_FCNTL_TRACE
+  zTrace = (pOp->p4.z ? pOp->p4.z : p->zSql);
+  if( zTrace ){
+    int j;
+    for(j=0; j<db->nDb; j++){
+      if( DbMaskTest(p->btreeMask, j)==0 ) continue;
+      sqlite3_file_control(db, db->aDb[j].zDbSName, SQLITE_FCNTL_TRACE, zTrace);
+    }
+  }
+#endif /* SQLITE_USE_FCNTL_TRACE */
+#ifdef SQLITE_DEBUG
+  if( (db->flags & SQLITE_SqlTrace)!=0
+   && (zTrace = (pOp->p4.z ? pOp->p4.z : p->zSql))!=0
+  ){
+    sqlite3DebugPrintf("SQL-trace: %s\n", zTrace);
+  }
+#endif /* SQLITE_DEBUG */
+#endif /* SQLITE_OMIT_TRACE */
+  assert( pOp->p2>0 );
+  if( pOp->p1>=sqlite3GlobalConfig.iOnceResetThreshold ){
+    for(i=1; i<p->nOp; i++){
+      if( p->aOp[i].opcode==OP_Once ) p->aOp[i].p1 = 0;
+    }
+    pOp->p1 = 0;
+  }
+  pOp->p1++;
+  goto jump_to_p2;
+}
+
+#ifdef SQLITE_ENABLE_CURSOR_HINTS
+/* Opcode: CursorHint P1 * * P4 *
+**
+** Provide a hint to cursor P1 that it only needs to return rows that
+** satisfy the Expr in P4.  TK_REGISTER terms in the P4 expression refer
+** to values currently held in registers.  TK_COLUMN terms in the P4
+** expression refer to columns in the b-tree to which cursor P1 is pointing.
+*/
+case OP_CursorHint: {
+  VdbeCursor *pC;
+
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  assert( pOp->p4type==P4_EXPR );
+  pC = p->apCsr[pOp->p1];
+  if( pC ){
+    assert( pC->eCurType==CURTYPE_BTREE );
+    sqlite3BtreeCursorHint(pC->uc.pCursor, BTREE_HINT_RANGE,
+                           pOp->p4.pExpr, aMem);
+  }
+  break;
+}
+#endif /* SQLITE_ENABLE_CURSOR_HINTS */
+
+/* Opcode: Noop * * * * *
+**
+** Do nothing.  This instruction is often useful as a jump
+** destination.
+*/
+/*
+** The magic Explain opcode are only inserted when explain==2 (which
+** is to say when the EXPLAIN QUERY PLAN syntax is used.)
+** This opcode records information from the optimizer.  It is the
+** the same as a no-op.  This opcodesnever appears in a real VM program.
+*/
+default: {          /* This is really OP_Noop and OP_Explain */
+  assert( pOp->opcode==OP_Noop || pOp->opcode==OP_Explain );
+  break;
+}
+
+/*****************************************************************************
+** The cases of the switch statement above this line should all be indented
+** by 6 spaces.  But the left-most 6 spaces have been removed to improve the
+** readability.  From this point on down, the normal indentation rules are
+** restored.
+*****************************************************************************/
+    }
+
+#ifdef VDBE_PROFILE
+    {
+      u64 endTime = sqlite3Hwtime();
+      if( endTime>start ) pOrigOp->cycles += endTime - start;
+      pOrigOp->cnt++;
+    }
+#endif
+
+    /* The following code adds nothing to the actual functionality
+    ** of the program.  It is only here for testing and debugging.
+    ** On the other hand, it does burn CPU cycles every time through
+    ** the evaluator loop.  So we can leave it out when NDEBUG is defined.
+    */
+#ifndef NDEBUG
+    assert( pOp>=&aOp[-1] && pOp<&aOp[p->nOp-1] );
+
+#ifdef SQLITE_DEBUG
+    if( db->flags & SQLITE_VdbeTrace ){
+      u8 opProperty = sqlite3OpcodeProperty[pOrigOp->opcode];
+      if( rc!=0 ) printf("rc=%d\n",rc);
+      if( opProperty & (OPFLG_OUT2) ){
+        registerTrace(pOrigOp->p2, &aMem[pOrigOp->p2]);
+      }
+      if( opProperty & OPFLG_OUT3 ){
+        registerTrace(pOrigOp->p3, &aMem[pOrigOp->p3]);
+      }
+    }
+#endif  /* SQLITE_DEBUG */
+#endif  /* NDEBUG */
+  }  /* The end of the for(;;) loop the loops through opcodes */
+
+  /* If we reach this point, it means that execution is finished with
+  ** an error of some kind.
+  */
+abort_due_to_error:
+  if( db->mallocFailed ) rc = SQLITE_NOMEM_BKPT;
+  assert( rc );
+  if( p->zErrMsg==0 && rc!=SQLITE_IOERR_NOMEM ){
+    sqlite3VdbeError(p, "%s", sqlite3ErrStr(rc));
+  }
+  p->rc = rc;
+  sqlite3SystemError(db, rc);
+  testcase( sqlite3GlobalConfig.xLog!=0 );
+  sqlite3_log(rc, "statement aborts at %d: [%s] %s", 
+                   (int)(pOp - aOp), p->zSql, p->zErrMsg);
+  sqlite3VdbeHalt(p);
+  if( rc==SQLITE_IOERR_NOMEM ) sqlite3OomFault(db);
+  rc = SQLITE_ERROR;
+  if( resetSchemaOnFault>0 ){
+    sqlite3ResetOneSchema(db, resetSchemaOnFault-1);
+  }
+
+  /* This is the only way out of this procedure.  We have to
+  ** release the mutexes on btrees that were acquired at the
+  ** top. */
+vdbe_return:
+  db->lastRowid = lastRowid;
+  testcase( nVmStep>0 );
+  p->aCounter[SQLITE_STMTSTATUS_VM_STEP] += (int)nVmStep;
+  sqlite3VdbeLeave(p);
+  assert( rc!=SQLITE_OK || nExtraDelete==0 
+       || sqlite3_strlike("DELETE%",p->zSql,0)!=0 
+  );
+  return rc;
+
+  /* Jump to here if a string or blob larger than SQLITE_MAX_LENGTH
+  ** is encountered.
+  */
+too_big:
+  sqlite3VdbeError(p, "string or blob too big");
+  rc = SQLITE_TOOBIG;
+  goto abort_due_to_error;
+
+  /* Jump to here if a malloc() fails.
+  */
+no_mem:
+  sqlite3OomFault(db);
+  sqlite3VdbeError(p, "out of memory");
+  rc = SQLITE_NOMEM_BKPT;
+  goto abort_due_to_error;
+
+  /* Jump to here if the sqlite3_interrupt() API sets the interrupt
+  ** flag.
+  */
+abort_due_to_interrupt:
+  assert( db->u1.isInterrupted );
+  rc = db->mallocFailed ? SQLITE_NOMEM_BKPT : SQLITE_INTERRUPT;
+  p->rc = rc;
+  sqlite3VdbeError(p, "%s", sqlite3ErrStr(rc));
+  goto abort_due_to_error;
+}
+
+
+/************** End of vdbe.c ************************************************/
+/************** Begin file vdbeblob.c ****************************************/
+/*
+** 2007 May 1
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains code used to implement incremental BLOB I/O.
+*/
+
+/* #include "sqliteInt.h" */
+/* #include "vdbeInt.h" */
+
+#ifndef SQLITE_OMIT_INCRBLOB
+
+/*
+** Valid sqlite3_blob* handles point to Incrblob structures.
+*/
+typedef struct Incrblob Incrblob;
+struct Incrblob {
+  int flags;              /* Copy of "flags" passed to sqlite3_blob_open() */
+  int nByte;              /* Size of open blob, in bytes */
+  int iOffset;            /* Byte offset of blob in cursor data */
+  int iCol;               /* Table column this handle is open on */
+  BtCursor *pCsr;         /* Cursor pointing at blob row */
+  sqlite3_stmt *pStmt;    /* Statement holding cursor open */
+  sqlite3 *db;            /* The associated database */
+  char *zDb;              /* Database name */
+  Table *pTab;            /* Table object */
+};
+
+
+/*
+** This function is used by both blob_open() and blob_reopen(). It seeks
+** the b-tree cursor associated with blob handle p to point to row iRow.
+** If successful, SQLITE_OK is returned and subsequent calls to
+** sqlite3_blob_read() or sqlite3_blob_write() access the specified row.
+**
+** If an error occurs, or if the specified row does not exist or does not
+** contain a value of type TEXT or BLOB in the column nominated when the
+** blob handle was opened, then an error code is returned and *pzErr may
+** be set to point to a buffer containing an error message. It is the
+** responsibility of the caller to free the error message buffer using
+** sqlite3DbFree().
+**
+** If an error does occur, then the b-tree cursor is closed. All subsequent
+** calls to sqlite3_blob_read(), blob_write() or blob_reopen() will 
+** immediately return SQLITE_ABORT.
+*/
+static int blobSeekToRow(Incrblob *p, sqlite3_int64 iRow, char **pzErr){
+  int rc;                         /* Error code */
+  char *zErr = 0;                 /* Error message */
+  Vdbe *v = (Vdbe *)p->pStmt;
+
+  /* Set the value of the SQL statements only variable to integer iRow. 
+  ** This is done directly instead of using sqlite3_bind_int64() to avoid 
+  ** triggering asserts related to mutexes.
+  */
+  assert( v->aVar[0].flags&MEM_Int );
+  v->aVar[0].u.i = iRow;
+
+  rc = sqlite3_step(p->pStmt);
+  if( rc==SQLITE_ROW ){
+    VdbeCursor *pC = v->apCsr[0];
+    u32 type = pC->aType[p->iCol];
+    if( type<12 ){
+      zErr = sqlite3MPrintf(p->db, "cannot open value of type %s",
+          type==0?"null": type==7?"real": "integer"
+      );
+      rc = SQLITE_ERROR;
+      sqlite3_finalize(p->pStmt);
+      p->pStmt = 0;
+    }else{
+      p->iOffset = pC->aType[p->iCol + pC->nField];
+      p->nByte = sqlite3VdbeSerialTypeLen(type);
+      p->pCsr =  pC->uc.pCursor;
+      sqlite3BtreeIncrblobCursor(p->pCsr);
+    }
+  }
+
+  if( rc==SQLITE_ROW ){
+    rc = SQLITE_OK;
+  }else if( p->pStmt ){
+    rc = sqlite3_finalize(p->pStmt);
+    p->pStmt = 0;
+    if( rc==SQLITE_OK ){
+      zErr = sqlite3MPrintf(p->db, "no such rowid: %lld", iRow);
+      rc = SQLITE_ERROR;
+    }else{
+      zErr = sqlite3MPrintf(p->db, "%s", sqlite3_errmsg(p->db));
+    }
+  }
+
+  assert( rc!=SQLITE_OK || zErr==0 );
+  assert( rc!=SQLITE_ROW && rc!=SQLITE_DONE );
+
+  *pzErr = zErr;
+  return rc;
+}
+
+/*
+** Open a blob handle.
+*/
+SQLITE_API int sqlite3_blob_open(
+  sqlite3* db,            /* The database connection */
+  const char *zDb,        /* The attached database containing the blob */
+  const char *zTable,     /* The table containing the blob */
+  const char *zColumn,    /* The column containing the blob */
+  sqlite_int64 iRow,      /* The row containing the glob */
+  int flags,              /* True -> read/write access, false -> read-only */
+  sqlite3_blob **ppBlob   /* Handle for accessing the blob returned here */
+){
+  int nAttempt = 0;
+  int iCol;               /* Index of zColumn in row-record */
+  int rc = SQLITE_OK;
+  char *zErr = 0;
+  Table *pTab;
+  Parse *pParse = 0;
+  Incrblob *pBlob = 0;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( ppBlob==0 ){
+    return SQLITE_MISUSE_BKPT;
+  }
+#endif
+  *ppBlob = 0;
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) || zTable==0 ){
+    return SQLITE_MISUSE_BKPT;
+  }
+#endif
+  flags = !!flags;                /* flags = (flags ? 1 : 0); */
+
+  sqlite3_mutex_enter(db->mutex);
+
+  pBlob = (Incrblob *)sqlite3DbMallocZero(db, sizeof(Incrblob));
+  if( !pBlob ) goto blob_open_out;
+  pParse = sqlite3StackAllocRaw(db, sizeof(*pParse));
+  if( !pParse ) goto blob_open_out;
+
+  do {
+    memset(pParse, 0, sizeof(Parse));
+    pParse->db = db;
+    sqlite3DbFree(db, zErr);
+    zErr = 0;
+
+    sqlite3BtreeEnterAll(db);
+    pTab = sqlite3LocateTable(pParse, 0, zTable, zDb);
+    if( pTab && IsVirtual(pTab) ){
+      pTab = 0;
+      sqlite3ErrorMsg(pParse, "cannot open virtual table: %s", zTable);
+    }
+    if( pTab && !HasRowid(pTab) ){
+      pTab = 0;
+      sqlite3ErrorMsg(pParse, "cannot open table without rowid: %s", zTable);
+    }
+#ifndef SQLITE_OMIT_VIEW
+    if( pTab && pTab->pSelect ){
+      pTab = 0;
+      sqlite3ErrorMsg(pParse, "cannot open view: %s", zTable);
+    }
+#endif
+    if( !pTab ){
+      if( pParse->zErrMsg ){
+        sqlite3DbFree(db, zErr);
+        zErr = pParse->zErrMsg;
+        pParse->zErrMsg = 0;
+      }
+      rc = SQLITE_ERROR;
+      sqlite3BtreeLeaveAll(db);
+      goto blob_open_out;
+    }
+    pBlob->pTab = pTab;
+    pBlob->zDb = db->aDb[sqlite3SchemaToIndex(db, pTab->pSchema)].zDbSName;
+
+    /* Now search pTab for the exact column. */
+    for(iCol=0; iCol<pTab->nCol; iCol++) {
+      if( sqlite3StrICmp(pTab->aCol[iCol].zName, zColumn)==0 ){
+        break;
+      }
+    }
+    if( iCol==pTab->nCol ){
+      sqlite3DbFree(db, zErr);
+      zErr = sqlite3MPrintf(db, "no such column: \"%s\"", zColumn);
+      rc = SQLITE_ERROR;
+      sqlite3BtreeLeaveAll(db);
+      goto blob_open_out;
+    }
+
+    /* If the value is being opened for writing, check that the
+    ** column is not indexed, and that it is not part of a foreign key. 
+    ** It is against the rules to open a column to which either of these
+    ** descriptions applies for writing.  */
+    if( flags ){
+      const char *zFault = 0;
+      Index *pIdx;
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+      if( db->flags&SQLITE_ForeignKeys ){
+        /* Check that the column is not part of an FK child key definition. It
+        ** is not necessary to check if it is part of a parent key, as parent
+        ** key columns must be indexed. The check below will pick up this 
+        ** case.  */
+        FKey *pFKey;
+        for(pFKey=pTab->pFKey; pFKey; pFKey=pFKey->pNextFrom){
+          int j;
+          for(j=0; j<pFKey->nCol; j++){
+            if( pFKey->aCol[j].iFrom==iCol ){
+              zFault = "foreign key";
+            }
+          }
+        }
+      }
+#endif
+      for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+        int j;
+        for(j=0; j<pIdx->nKeyCol; j++){
+          /* FIXME: Be smarter about indexes that use expressions */
+          if( pIdx->aiColumn[j]==iCol || pIdx->aiColumn[j]==XN_EXPR ){
+            zFault = "indexed";
+          }
+        }
+      }
+      if( zFault ){
+        sqlite3DbFree(db, zErr);
+        zErr = sqlite3MPrintf(db, "cannot open %s column for writing", zFault);
+        rc = SQLITE_ERROR;
+        sqlite3BtreeLeaveAll(db);
+        goto blob_open_out;
+      }
+    }
+
+    pBlob->pStmt = (sqlite3_stmt *)sqlite3VdbeCreate(pParse);
+    assert( pBlob->pStmt || db->mallocFailed );
+    if( pBlob->pStmt ){
+      
+      /* This VDBE program seeks a btree cursor to the identified 
+      ** db/table/row entry. The reason for using a vdbe program instead
+      ** of writing code to use the b-tree layer directly is that the
+      ** vdbe program will take advantage of the various transaction,
+      ** locking and error handling infrastructure built into the vdbe.
+      **
+      ** After seeking the cursor, the vdbe executes an OP_ResultRow.
+      ** Code external to the Vdbe then "borrows" the b-tree cursor and
+      ** uses it to implement the blob_read(), blob_write() and 
+      ** blob_bytes() functions.
+      **
+      ** The sqlite3_blob_close() function finalizes the vdbe program,
+      ** which closes the b-tree cursor and (possibly) commits the 
+      ** transaction.
+      */
+      static const int iLn = VDBE_OFFSET_LINENO(2);
+      static const VdbeOpList openBlob[] = {
+        {OP_TableLock,      0, 0, 0},  /* 0: Acquire a read or write lock */
+        {OP_OpenRead,       0, 0, 0},  /* 1: Open a cursor */
+        {OP_Variable,       1, 1, 0},  /* 2: Move ?1 into reg[1] */
+        {OP_NotExists,      0, 7, 1},  /* 3: Seek the cursor */
+        {OP_Column,         0, 0, 1},  /* 4  */
+        {OP_ResultRow,      1, 0, 0},  /* 5  */
+        {OP_Goto,           0, 2, 0},  /* 6  */
+        {OP_Close,          0, 0, 0},  /* 7  */
+        {OP_Halt,           0, 0, 0},  /* 8  */
+      };
+      Vdbe *v = (Vdbe *)pBlob->pStmt;
+      int iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+      VdbeOp *aOp;
+
+      sqlite3VdbeAddOp4Int(v, OP_Transaction, iDb, flags, 
+                           pTab->pSchema->schema_cookie,
+                           pTab->pSchema->iGeneration);
+      sqlite3VdbeChangeP5(v, 1);     
+      aOp = sqlite3VdbeAddOpList(v, ArraySize(openBlob), openBlob, iLn);
+
+      /* Make sure a mutex is held on the table to be accessed */
+      sqlite3VdbeUsesBtree(v, iDb); 
+
+      if( db->mallocFailed==0 ){
+        assert( aOp!=0 );
+        /* Configure the OP_TableLock instruction */
+#ifdef SQLITE_OMIT_SHARED_CACHE
+        aOp[0].opcode = OP_Noop;
+#else
+        aOp[0].p1 = iDb;
+        aOp[0].p2 = pTab->tnum;
+        aOp[0].p3 = flags;
+        sqlite3VdbeChangeP4(v, 1, pTab->zName, P4_TRANSIENT);
+      }
+      if( db->mallocFailed==0 ){
+#endif
+
+        /* Remove either the OP_OpenWrite or OpenRead. Set the P2 
+        ** parameter of the other to pTab->tnum.  */
+        if( flags ) aOp[1].opcode = OP_OpenWrite;
+        aOp[1].p2 = pTab->tnum;
+        aOp[1].p3 = iDb;   
+
+        /* Configure the number of columns. Configure the cursor to
+        ** think that the table has one more column than it really
+        ** does. An OP_Column to retrieve this imaginary column will
+        ** always return an SQL NULL. This is useful because it means
+        ** we can invoke OP_Column to fill in the vdbe cursors type 
+        ** and offset cache without causing any IO.
+        */
+        aOp[1].p4type = P4_INT32;
+        aOp[1].p4.i = pTab->nCol+1;
+        aOp[4].p2 = pTab->nCol;
+
+        pParse->nVar = 1;
+        pParse->nMem = 1;
+        pParse->nTab = 1;
+        sqlite3VdbeMakeReady(v, pParse);
+      }
+    }
+   
+    pBlob->flags = flags;
+    pBlob->iCol = iCol;
+    pBlob->db = db;
+    sqlite3BtreeLeaveAll(db);
+    if( db->mallocFailed ){
+      goto blob_open_out;
+    }
+    sqlite3_bind_int64(pBlob->pStmt, 1, iRow);
+    rc = blobSeekToRow(pBlob, iRow, &zErr);
+  } while( (++nAttempt)<SQLITE_MAX_SCHEMA_RETRY && rc==SQLITE_SCHEMA );
+
+blob_open_out:
+  if( rc==SQLITE_OK && db->mallocFailed==0 ){
+    *ppBlob = (sqlite3_blob *)pBlob;
+  }else{
+    if( pBlob && pBlob->pStmt ) sqlite3VdbeFinalize((Vdbe *)pBlob->pStmt);
+    sqlite3DbFree(db, pBlob);
+  }
+  sqlite3ErrorWithMsg(db, rc, (zErr ? "%s" : 0), zErr);
+  sqlite3DbFree(db, zErr);
+  sqlite3ParserReset(pParse);
+  sqlite3StackFree(db, pParse);
+  rc = sqlite3ApiExit(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+/*
+** Close a blob handle that was previously created using
+** sqlite3_blob_open().
+*/
+SQLITE_API int sqlite3_blob_close(sqlite3_blob *pBlob){
+  Incrblob *p = (Incrblob *)pBlob;
+  int rc;
+  sqlite3 *db;
+
+  if( p ){
+    db = p->db;
+    sqlite3_mutex_enter(db->mutex);
+    rc = sqlite3_finalize(p->pStmt);
+    sqlite3DbFree(db, p);
+    sqlite3_mutex_leave(db->mutex);
+  }else{
+    rc = SQLITE_OK;
+  }
+  return rc;
+}
+
+/*
+** Perform a read or write operation on a blob
+*/
+static int blobReadWrite(
+  sqlite3_blob *pBlob, 
+  void *z, 
+  int n, 
+  int iOffset, 
+  int (*xCall)(BtCursor*, u32, u32, void*)
+){
+  int rc;
+  Incrblob *p = (Incrblob *)pBlob;
+  Vdbe *v;
+  sqlite3 *db;
+
+  if( p==0 ) return SQLITE_MISUSE_BKPT;
+  db = p->db;
+  sqlite3_mutex_enter(db->mutex);
+  v = (Vdbe*)p->pStmt;
+
+  if( n<0 || iOffset<0 || ((sqlite3_int64)iOffset+n)>p->nByte ){
+    /* Request is out of range. Return a transient error. */
+    rc = SQLITE_ERROR;
+  }else if( v==0 ){
+    /* If there is no statement handle, then the blob-handle has
+    ** already been invalidated. Return SQLITE_ABORT in this case.
+    */
+    rc = SQLITE_ABORT;
+  }else{
+    /* Call either BtreeData() or BtreePutData(). If SQLITE_ABORT is
+    ** returned, clean-up the statement handle.
+    */
+    assert( db == v->db );
+    sqlite3BtreeEnterCursor(p->pCsr);
+
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+    if( xCall==sqlite3BtreePutData && db->xPreUpdateCallback ){
+      /* If a pre-update hook is registered and this is a write cursor, 
+      ** invoke it here. 
+      ** 
+      ** TODO: The preupdate-hook is passed SQLITE_DELETE, even though this
+      ** operation should really be an SQLITE_UPDATE. This is probably
+      ** incorrect, but is convenient because at this point the new.* values 
+      ** are not easily obtainable. And for the sessions module, an 
+      ** SQLITE_UPDATE where the PK columns do not change is handled in the 
+      ** same way as an SQLITE_DELETE (the SQLITE_DELETE code is actually
+      ** slightly more efficient). Since you cannot write to a PK column
+      ** using the incremental-blob API, this works. For the sessions module
+      ** anyhow.
+      */
+      sqlite3_int64 iKey;
+      iKey = sqlite3BtreeIntegerKey(p->pCsr);
+      sqlite3VdbePreUpdateHook(
+          v, v->apCsr[0], SQLITE_DELETE, p->zDb, p->pTab, iKey, -1
+      );
+    }
+#endif
+
+    rc = xCall(p->pCsr, iOffset+p->iOffset, n, z);
+    sqlite3BtreeLeaveCursor(p->pCsr);
+    if( rc==SQLITE_ABORT ){
+      sqlite3VdbeFinalize(v);
+      p->pStmt = 0;
+    }else{
+      v->rc = rc;
+    }
+  }
+  sqlite3Error(db, rc);
+  rc = sqlite3ApiExit(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+/*
+** Read data from a blob handle.
+*/
+SQLITE_API int sqlite3_blob_read(sqlite3_blob *pBlob, void *z, int n, int iOffset){
+  return blobReadWrite(pBlob, z, n, iOffset, sqlite3BtreeData);
+}
+
+/*
+** Write data to a blob handle.
+*/
+SQLITE_API int sqlite3_blob_write(sqlite3_blob *pBlob, const void *z, int n, int iOffset){
+  return blobReadWrite(pBlob, (void *)z, n, iOffset, sqlite3BtreePutData);
+}
+
+/*
+** Query a blob handle for the size of the data.
+**
+** The Incrblob.nByte field is fixed for the lifetime of the Incrblob
+** so no mutex is required for access.
+*/
+SQLITE_API int sqlite3_blob_bytes(sqlite3_blob *pBlob){
+  Incrblob *p = (Incrblob *)pBlob;
+  return (p && p->pStmt) ? p->nByte : 0;
+}
+
+/*
+** Move an existing blob handle to point to a different row of the same
+** database table.
+**
+** If an error occurs, or if the specified row does not exist or does not
+** contain a blob or text value, then an error code is returned and the
+** database handle error code and message set. If this happens, then all 
+** subsequent calls to sqlite3_blob_xxx() functions (except blob_close()) 
+** immediately return SQLITE_ABORT.
+*/
+SQLITE_API int sqlite3_blob_reopen(sqlite3_blob *pBlob, sqlite3_int64 iRow){
+  int rc;
+  Incrblob *p = (Incrblob *)pBlob;
+  sqlite3 *db;
+
+  if( p==0 ) return SQLITE_MISUSE_BKPT;
+  db = p->db;
+  sqlite3_mutex_enter(db->mutex);
+
+  if( p->pStmt==0 ){
+    /* If there is no statement handle, then the blob-handle has
+    ** already been invalidated. Return SQLITE_ABORT in this case.
+    */
+    rc = SQLITE_ABORT;
+  }else{
+    char *zErr;
+    rc = blobSeekToRow(p, iRow, &zErr);
+    if( rc!=SQLITE_OK ){
+      sqlite3ErrorWithMsg(db, rc, (zErr ? "%s" : 0), zErr);
+      sqlite3DbFree(db, zErr);
+    }
+    assert( rc!=SQLITE_SCHEMA );
+  }
+
+  rc = sqlite3ApiExit(db, rc);
+  assert( rc==SQLITE_OK || p->pStmt==0 );
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+#endif /* #ifndef SQLITE_OMIT_INCRBLOB */
+
+/************** End of vdbeblob.c ********************************************/
+/************** Begin file vdbesort.c ****************************************/
+/*
+** 2011-07-09
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains code for the VdbeSorter object, used in concert with
+** a VdbeCursor to sort large numbers of keys for CREATE INDEX statements
+** or by SELECT statements with ORDER BY clauses that cannot be satisfied
+** using indexes and without LIMIT clauses.
+**
+** The VdbeSorter object implements a multi-threaded external merge sort
+** algorithm that is efficient even if the number of elements being sorted
+** exceeds the available memory.
+**
+** Here is the (internal, non-API) interface between this module and the
+** rest of the SQLite system:
+**
+**    sqlite3VdbeSorterInit()       Create a new VdbeSorter object.
+**
+**    sqlite3VdbeSorterWrite()      Add a single new row to the VdbeSorter
+**                                  object.  The row is a binary blob in the
+**                                  OP_MakeRecord format that contains both
+**                                  the ORDER BY key columns and result columns
+**                                  in the case of a SELECT w/ ORDER BY, or
+**                                  the complete record for an index entry
+**                                  in the case of a CREATE INDEX.
+**
+**    sqlite3VdbeSorterRewind()     Sort all content previously added.
+**                                  Position the read cursor on the
+**                                  first sorted element.
+**
+**    sqlite3VdbeSorterNext()       Advance the read cursor to the next sorted
+**                                  element.
+**
+**    sqlite3VdbeSorterRowkey()     Return the complete binary blob for the
+**                                  row currently under the read cursor.
+**
+**    sqlite3VdbeSorterCompare()    Compare the binary blob for the row
+**                                  currently under the read cursor against
+**                                  another binary blob X and report if
+**                                  X is strictly less than the read cursor.
+**                                  Used to enforce uniqueness in a
+**                                  CREATE UNIQUE INDEX statement.
+**
+**    sqlite3VdbeSorterClose()      Close the VdbeSorter object and reclaim
+**                                  all resources.
+**
+**    sqlite3VdbeSorterReset()      Refurbish the VdbeSorter for reuse.  This
+**                                  is like Close() followed by Init() only
+**                                  much faster.
+**
+** The interfaces above must be called in a particular order.  Write() can 
+** only occur in between Init()/Reset() and Rewind().  Next(), Rowkey(), and
+** Compare() can only occur in between Rewind() and Close()/Reset(). i.e.
+**
+**   Init()
+**   for each record: Write()
+**   Rewind()
+**     Rowkey()/Compare()
+**   Next() 
+**   Close()
+**
+** Algorithm:
+**
+** Records passed to the sorter via calls to Write() are initially held 
+** unsorted in main memory. Assuming the amount of memory used never exceeds
+** a threshold, when Rewind() is called the set of records is sorted using
+** an in-memory merge sort. In this case, no temporary files are required
+** and subsequent calls to Rowkey(), Next() and Compare() read records 
+** directly from main memory.
+**
+** If the amount of space used to store records in main memory exceeds the
+** threshold, then the set of records currently in memory are sorted and
+** written to a temporary file in "Packed Memory Array" (PMA) format.
+** A PMA created at this point is known as a "level-0 PMA". Higher levels
+** of PMAs may be created by merging existing PMAs together - for example
+** merging two or more level-0 PMAs together creates a level-1 PMA.
+**
+** The threshold for the amount of main memory to use before flushing 
+** records to a PMA is roughly the same as the limit configured for the
+** page-cache of the main database. Specifically, the threshold is set to 
+** the value returned by "PRAGMA main.page_size" multipled by 
+** that returned by "PRAGMA main.cache_size", in bytes.
+**
+** If the sorter is running in single-threaded mode, then all PMAs generated
+** are appended to a single temporary file. Or, if the sorter is running in
+** multi-threaded mode then up to (N+1) temporary files may be opened, where
+** N is the configured number of worker threads. In this case, instead of
+** sorting the records and writing the PMA to a temporary file itself, the
+** calling thread usually launches a worker thread to do so. Except, if
+** there are already N worker threads running, the main thread does the work
+** itself.
+**
+** The sorter is running in multi-threaded mode if (a) the library was built
+** with pre-processor symbol SQLITE_MAX_WORKER_THREADS set to a value greater
+** than zero, and (b) worker threads have been enabled at runtime by calling
+** "PRAGMA threads=N" with some value of N greater than 0.
+**
+** When Rewind() is called, any data remaining in memory is flushed to a 
+** final PMA. So at this point the data is stored in some number of sorted
+** PMAs within temporary files on disk.
+**
+** If there are fewer than SORTER_MAX_MERGE_COUNT PMAs in total and the
+** sorter is running in single-threaded mode, then these PMAs are merged
+** incrementally as keys are retreived from the sorter by the VDBE.  The
+** MergeEngine object, described in further detail below, performs this
+** merge.
+**
+** Or, if running in multi-threaded mode, then a background thread is
+** launched to merge the existing PMAs. Once the background thread has
+** merged T bytes of data into a single sorted PMA, the main thread 
+** begins reading keys from that PMA while the background thread proceeds
+** with merging the next T bytes of data. And so on.
+**
+** Parameter T is set to half the value of the memory threshold used 
+** by Write() above to determine when to create a new PMA.
+**
+** If there are more than SORTER_MAX_MERGE_COUNT PMAs in total when 
+** Rewind() is called, then a hierarchy of incremental-merges is used. 
+** First, T bytes of data from the first SORTER_MAX_MERGE_COUNT PMAs on 
+** disk are merged together. Then T bytes of data from the second set, and
+** so on, such that no operation ever merges more than SORTER_MAX_MERGE_COUNT
+** PMAs at a time. This done is to improve locality.
+**
+** If running in multi-threaded mode and there are more than
+** SORTER_MAX_MERGE_COUNT PMAs on disk when Rewind() is called, then more
+** than one background thread may be created. Specifically, there may be
+** one background thread for each temporary file on disk, and one background
+** thread to merge the output of each of the others to a single PMA for
+** the main thread to read from.
+*/
+/* #include "sqliteInt.h" */
+/* #include "vdbeInt.h" */
+
+/* 
+** If SQLITE_DEBUG_SORTER_THREADS is defined, this module outputs various
+** messages to stderr that may be helpful in understanding the performance
+** characteristics of the sorter in multi-threaded mode.
+*/
+#if 0
+# define SQLITE_DEBUG_SORTER_THREADS 1
+#endif
+
+/*
+** Hard-coded maximum amount of data to accumulate in memory before flushing
+** to a level 0 PMA. The purpose of this limit is to prevent various integer
+** overflows. 512MiB.
+*/
+#define SQLITE_MAX_PMASZ    (1<<29)
+
+/*
+** Private objects used by the sorter
+*/
+typedef struct MergeEngine MergeEngine;     /* Merge PMAs together */
+typedef struct PmaReader PmaReader;         /* Incrementally read one PMA */
+typedef struct PmaWriter PmaWriter;         /* Incrementally write one PMA */
+typedef struct SorterRecord SorterRecord;   /* A record being sorted */
+typedef struct SortSubtask SortSubtask;     /* A sub-task in the sort process */
+typedef struct SorterFile SorterFile;       /* Temporary file object wrapper */
+typedef struct SorterList SorterList;       /* In-memory list of records */
+typedef struct IncrMerger IncrMerger;       /* Read & merge multiple PMAs */
+
+/*
+** A container for a temp file handle and the current amount of data 
+** stored in the file.
+*/
+struct SorterFile {
+  sqlite3_file *pFd;              /* File handle */
+  i64 iEof;                       /* Bytes of data stored in pFd */
+};
+
+/*
+** An in-memory list of objects to be sorted.
+**
+** If aMemory==0 then each object is allocated separately and the objects
+** are connected using SorterRecord.u.pNext.  If aMemory!=0 then all objects
+** are stored in the aMemory[] bulk memory, one right after the other, and
+** are connected using SorterRecord.u.iNext.
+*/
+struct SorterList {
+  SorterRecord *pList;            /* Linked list of records */
+  u8 *aMemory;                    /* If non-NULL, bulk memory to hold pList */
+  int szPMA;                      /* Size of pList as PMA in bytes */
+};
+
+/*
+** The MergeEngine object is used to combine two or more smaller PMAs into
+** one big PMA using a merge operation.  Separate PMAs all need to be
+** combined into one big PMA in order to be able to step through the sorted
+** records in order.
+**
+** The aReadr[] array contains a PmaReader object for each of the PMAs being
+** merged.  An aReadr[] object either points to a valid key or else is at EOF.
+** ("EOF" means "End Of File".  When aReadr[] is at EOF there is no more data.)
+** For the purposes of the paragraphs below, we assume that the array is
+** actually N elements in size, where N is the smallest power of 2 greater
+** to or equal to the number of PMAs being merged. The extra aReadr[] elements
+** are treated as if they are empty (always at EOF).
+**
+** The aTree[] array is also N elements in size. The value of N is stored in
+** the MergeEngine.nTree variable.
+**
+** The final (N/2) elements of aTree[] contain the results of comparing
+** pairs of PMA keys together. Element i contains the result of 
+** comparing aReadr[2*i-N] and aReadr[2*i-N+1]. Whichever key is smaller, the
+** aTree element is set to the index of it. 
+**
+** For the purposes of this comparison, EOF is considered greater than any
+** other key value. If the keys are equal (only possible with two EOF
+** values), it doesn't matter which index is stored.
+**
+** The (N/4) elements of aTree[] that precede the final (N/2) described 
+** above contains the index of the smallest of each block of 4 PmaReaders
+** And so on. So that aTree[1] contains the index of the PmaReader that 
+** currently points to the smallest key value. aTree[0] is unused.
+**
+** Example:
+**
+**     aReadr[0] -> Banana
+**     aReadr[1] -> Feijoa
+**     aReadr[2] -> Elderberry
+**     aReadr[3] -> Currant
+**     aReadr[4] -> Grapefruit
+**     aReadr[5] -> Apple
+**     aReadr[6] -> Durian
+**     aReadr[7] -> EOF
+**
+**     aTree[] = { X, 5   0, 5    0, 3, 5, 6 }
+**
+** The current element is "Apple" (the value of the key indicated by 
+** PmaReader 5). When the Next() operation is invoked, PmaReader 5 will
+** be advanced to the next key in its segment. Say the next key is
+** "Eggplant":
+**
+**     aReadr[5] -> Eggplant
+**
+** The contents of aTree[] are updated first by comparing the new PmaReader
+** 5 key to the current key of PmaReader 4 (still "Grapefruit"). The PmaReader
+** 5 value is still smaller, so aTree[6] is set to 5. And so on up the tree.
+** The value of PmaReader 6 - "Durian" - is now smaller than that of PmaReader
+** 5, so aTree[3] is set to 6. Key 0 is smaller than key 6 (Banana<Durian),
+** so the value written into element 1 of the array is 0. As follows:
+**
+**     aTree[] = { X, 0   0, 6    0, 3, 5, 6 }
+**
+** In other words, each time we advance to the next sorter element, log2(N)
+** key comparison operations are required, where N is the number of segments
+** being merged (rounded up to the next power of 2).
+*/
+struct MergeEngine {
+  int nTree;                 /* Used size of aTree/aReadr (power of 2) */
+  SortSubtask *pTask;        /* Used by this thread only */
+  int *aTree;                /* Current state of incremental merge */
+  PmaReader *aReadr;         /* Array of PmaReaders to merge data from */
+};
+
+/*
+** This object represents a single thread of control in a sort operation.
+** Exactly VdbeSorter.nTask instances of this object are allocated
+** as part of each VdbeSorter object. Instances are never allocated any
+** other way. VdbeSorter.nTask is set to the number of worker threads allowed
+** (see SQLITE_CONFIG_WORKER_THREADS) plus one (the main thread).  Thus for
+** single-threaded operation, there is exactly one instance of this object
+** and for multi-threaded operation there are two or more instances.
+**
+** Essentially, this structure contains all those fields of the VdbeSorter
+** structure for which each thread requires a separate instance. For example,
+** each thread requries its own UnpackedRecord object to unpack records in
+** as part of comparison operations.
+**
+** Before a background thread is launched, variable bDone is set to 0. Then, 
+** right before it exits, the thread itself sets bDone to 1. This is used for 
+** two purposes:
+**
+**   1. When flushing the contents of memory to a level-0 PMA on disk, to
+**      attempt to select a SortSubtask for which there is not already an
+**      active background thread (since doing so causes the main thread
+**      to block until it finishes).
+**
+**   2. If SQLITE_DEBUG_SORTER_THREADS is defined, to determine if a call
+**      to sqlite3ThreadJoin() is likely to block. Cases that are likely to
+**      block provoke debugging output.
+**
+** In both cases, the effects of the main thread seeing (bDone==0) even
+** after the thread has finished are not dire. So we don't worry about
+** memory barriers and such here.
+*/
+typedef int (*SorterCompare)(SortSubtask*,int*,const void*,int,const void*,int);
+struct SortSubtask {
+  SQLiteThread *pThread;          /* Background thread, if any */
+  int bDone;                      /* Set if thread is finished but not joined */
+  VdbeSorter *pSorter;            /* Sorter that owns this sub-task */
+  UnpackedRecord *pUnpacked;      /* Space to unpack a record */
+  SorterList list;                /* List for thread to write to a PMA */
+  int nPMA;                       /* Number of PMAs currently in file */
+  SorterCompare xCompare;         /* Compare function to use */
+  SorterFile file;                /* Temp file for level-0 PMAs */
+  SorterFile file2;               /* Space for other PMAs */
+};
+
+
+/*
+** Main sorter structure. A single instance of this is allocated for each 
+** sorter cursor created by the VDBE.
+**
+** mxKeysize:
+**   As records are added to the sorter by calls to sqlite3VdbeSorterWrite(),
+**   this variable is updated so as to be set to the size on disk of the
+**   largest record in the sorter.
+*/
+struct VdbeSorter {
+  int mnPmaSize;                  /* Minimum PMA size, in bytes */
+  int mxPmaSize;                  /* Maximum PMA size, in bytes.  0==no limit */
+  int mxKeysize;                  /* Largest serialized key seen so far */
+  int pgsz;                       /* Main database page size */
+  PmaReader *pReader;             /* Readr data from here after Rewind() */
+  MergeEngine *pMerger;           /* Or here, if bUseThreads==0 */
+  sqlite3 *db;                    /* Database connection */
+  KeyInfo *pKeyInfo;              /* How to compare records */
+  UnpackedRecord *pUnpacked;      /* Used by VdbeSorterCompare() */
+  SorterList list;                /* List of in-memory records */
+  int iMemory;                    /* Offset of free space in list.aMemory */
+  int nMemory;                    /* Size of list.aMemory allocation in bytes */
+  u8 bUsePMA;                     /* True if one or more PMAs created */
+  u8 bUseThreads;                 /* True to use background threads */
+  u8 iPrev;                       /* Previous thread used to flush PMA */
+  u8 nTask;                       /* Size of aTask[] array */
+  u8 typeMask;
+  SortSubtask aTask[1];           /* One or more subtasks */
+};
+
+#define SORTER_TYPE_INTEGER 0x01
+#define SORTER_TYPE_TEXT    0x02
+
+/*
+** An instance of the following object is used to read records out of a
+** PMA, in sorted order.  The next key to be read is cached in nKey/aKey.
+** aKey might point into aMap or into aBuffer.  If neither of those locations
+** contain a contiguous representation of the key, then aAlloc is allocated
+** and the key is copied into aAlloc and aKey is made to poitn to aAlloc.
+**
+** pFd==0 at EOF.
+*/
+struct PmaReader {
+  i64 iReadOff;               /* Current read offset */
+  i64 iEof;                   /* 1 byte past EOF for this PmaReader */
+  int nAlloc;                 /* Bytes of space at aAlloc */
+  int nKey;                   /* Number of bytes in key */
+  sqlite3_file *pFd;          /* File handle we are reading from */
+  u8 *aAlloc;                 /* Space for aKey if aBuffer and pMap wont work */
+  u8 *aKey;                   /* Pointer to current key */
+  u8 *aBuffer;                /* Current read buffer */
+  int nBuffer;                /* Size of read buffer in bytes */
+  u8 *aMap;                   /* Pointer to mapping of entire file */
+  IncrMerger *pIncr;          /* Incremental merger */
+};
+
+/*
+** Normally, a PmaReader object iterates through an existing PMA stored 
+** within a temp file. However, if the PmaReader.pIncr variable points to
+** an object of the following type, it may be used to iterate/merge through
+** multiple PMAs simultaneously.
+**
+** There are two types of IncrMerger object - single (bUseThread==0) and 
+** multi-threaded (bUseThread==1). 
+**
+** A multi-threaded IncrMerger object uses two temporary files - aFile[0] 
+** and aFile[1]. Neither file is allowed to grow to more than mxSz bytes in 
+** size. When the IncrMerger is initialized, it reads enough data from 
+** pMerger to populate aFile[0]. It then sets variables within the 
+** corresponding PmaReader object to read from that file and kicks off 
+** a background thread to populate aFile[1] with the next mxSz bytes of 
+** sorted record data from pMerger. 
+**
+** When the PmaReader reaches the end of aFile[0], it blocks until the
+** background thread has finished populating aFile[1]. It then exchanges
+** the contents of the aFile[0] and aFile[1] variables within this structure,
+** sets the PmaReader fields to read from the new aFile[0] and kicks off
+** another background thread to populate the new aFile[1]. And so on, until
+** the contents of pMerger are exhausted.
+**
+** A single-threaded IncrMerger does not open any temporary files of its
+** own. Instead, it has exclusive access to mxSz bytes of space beginning
+** at offset iStartOff of file pTask->file2. And instead of using a 
+** background thread to prepare data for the PmaReader, with a single
+** threaded IncrMerger the allocate part of pTask->file2 is "refilled" with
+** keys from pMerger by the calling thread whenever the PmaReader runs out
+** of data.
+*/
+struct IncrMerger {
+  SortSubtask *pTask;             /* Task that owns this merger */
+  MergeEngine *pMerger;           /* Merge engine thread reads data from */
+  i64 iStartOff;                  /* Offset to start writing file at */
+  int mxSz;                       /* Maximum bytes of data to store */
+  int bEof;                       /* Set to true when merge is finished */
+  int bUseThread;                 /* True to use a bg thread for this object */
+  SorterFile aFile[2];            /* aFile[0] for reading, [1] for writing */
+};
+
+/*
+** An instance of this object is used for writing a PMA.
+**
+** The PMA is written one record at a time.  Each record is of an arbitrary
+** size.  But I/O is more efficient if it occurs in page-sized blocks where
+** each block is aligned on a page boundary.  This object caches writes to
+** the PMA so that aligned, page-size blocks are written.
+*/
+struct PmaWriter {
+  int eFWErr;                     /* Non-zero if in an error state */
+  u8 *aBuffer;                    /* Pointer to write buffer */
+  int nBuffer;                    /* Size of write buffer in bytes */
+  int iBufStart;                  /* First byte of buffer to write */
+  int iBufEnd;                    /* Last byte of buffer to write */
+  i64 iWriteOff;                  /* Offset of start of buffer in file */
+  sqlite3_file *pFd;              /* File handle to write to */
+};
+
+/*
+** This object is the header on a single record while that record is being
+** held in memory and prior to being written out as part of a PMA.
+**
+** How the linked list is connected depends on how memory is being managed
+** by this module. If using a separate allocation for each in-memory record
+** (VdbeSorter.list.aMemory==0), then the list is always connected using the
+** SorterRecord.u.pNext pointers.
+**
+** Or, if using the single large allocation method (VdbeSorter.list.aMemory!=0),
+** then while records are being accumulated the list is linked using the
+** SorterRecord.u.iNext offset. This is because the aMemory[] array may
+** be sqlite3Realloc()ed while records are being accumulated. Once the VM
+** has finished passing records to the sorter, or when the in-memory buffer
+** is full, the list is sorted. As part of the sorting process, it is
+** converted to use the SorterRecord.u.pNext pointers. See function
+** vdbeSorterSort() for details.
+*/
+struct SorterRecord {
+  int nVal;                       /* Size of the record in bytes */
+  union {
+    SorterRecord *pNext;          /* Pointer to next record in list */
+    int iNext;                    /* Offset within aMemory of next record */
+  } u;
+  /* The data for the record immediately follows this header */
+};
+
+/* Return a pointer to the buffer containing the record data for SorterRecord
+** object p. Should be used as if:
+**
+**   void *SRVAL(SorterRecord *p) { return (void*)&p[1]; }
+*/
+#define SRVAL(p) ((void*)((SorterRecord*)(p) + 1))
+
+
+/* Maximum number of PMAs that a single MergeEngine can merge */
+#define SORTER_MAX_MERGE_COUNT 16
+
+static int vdbeIncrSwap(IncrMerger*);
+static void vdbeIncrFree(IncrMerger *);
+
+/*
+** Free all memory belonging to the PmaReader object passed as the
+** argument. All structure fields are set to zero before returning.
+*/
+static void vdbePmaReaderClear(PmaReader *pReadr){
+  sqlite3_free(pReadr->aAlloc);
+  sqlite3_free(pReadr->aBuffer);
+  if( pReadr->aMap ) sqlite3OsUnfetch(pReadr->pFd, 0, pReadr->aMap);
+  vdbeIncrFree(pReadr->pIncr);
+  memset(pReadr, 0, sizeof(PmaReader));
+}
+
+/*
+** Read the next nByte bytes of data from the PMA p.
+** If successful, set *ppOut to point to a buffer containing the data
+** and return SQLITE_OK. Otherwise, if an error occurs, return an SQLite
+** error code.
+**
+** The buffer returned in *ppOut is only valid until the
+** next call to this function.
+*/
+static int vdbePmaReadBlob(
+  PmaReader *p,                   /* PmaReader from which to take the blob */
+  int nByte,                      /* Bytes of data to read */
+  u8 **ppOut                      /* OUT: Pointer to buffer containing data */
+){
+  int iBuf;                       /* Offset within buffer to read from */
+  int nAvail;                     /* Bytes of data available in buffer */
+
+  if( p->aMap ){
+    *ppOut = &p->aMap[p->iReadOff];
+    p->iReadOff += nByte;
+    return SQLITE_OK;
+  }
+
+  assert( p->aBuffer );
+
+  /* If there is no more data to be read from the buffer, read the next 
+  ** p->nBuffer bytes of data from the file into it. Or, if there are less
+  ** than p->nBuffer bytes remaining in the PMA, read all remaining data.  */
+  iBuf = p->iReadOff % p->nBuffer;
+  if( iBuf==0 ){
+    int nRead;                    /* Bytes to read from disk */
+    int rc;                       /* sqlite3OsRead() return code */
+
+    /* Determine how many bytes of data to read. */
+    if( (p->iEof - p->iReadOff) > (i64)p->nBuffer ){
+      nRead = p->nBuffer;
+    }else{
+      nRead = (int)(p->iEof - p->iReadOff);
+    }
+    assert( nRead>0 );
+
+    /* Readr data from the file. Return early if an error occurs. */
+    rc = sqlite3OsRead(p->pFd, p->aBuffer, nRead, p->iReadOff);
+    assert( rc!=SQLITE_IOERR_SHORT_READ );
+    if( rc!=SQLITE_OK ) return rc;
+  }
+  nAvail = p->nBuffer - iBuf; 
+
+  if( nByte<=nAvail ){
+    /* The requested data is available in the in-memory buffer. In this
+    ** case there is no need to make a copy of the data, just return a 
+    ** pointer into the buffer to the caller.  */
+    *ppOut = &p->aBuffer[iBuf];
+    p->iReadOff += nByte;
+  }else{
+    /* The requested data is not all available in the in-memory buffer.
+    ** In this case, allocate space at p->aAlloc[] to copy the requested
+    ** range into. Then return a copy of pointer p->aAlloc to the caller.  */
+    int nRem;                     /* Bytes remaining to copy */
+
+    /* Extend the p->aAlloc[] allocation if required. */
+    if( p->nAlloc<nByte ){
+      u8 *aNew;
+      int nNew = MAX(128, p->nAlloc*2);
+      while( nByte>nNew ) nNew = nNew*2;
+      aNew = sqlite3Realloc(p->aAlloc, nNew);
+      if( !aNew ) return SQLITE_NOMEM_BKPT;
+      p->nAlloc = nNew;
+      p->aAlloc = aNew;
+    }
+
+    /* Copy as much data as is available in the buffer into the start of
+    ** p->aAlloc[].  */
+    memcpy(p->aAlloc, &p->aBuffer[iBuf], nAvail);
+    p->iReadOff += nAvail;
+    nRem = nByte - nAvail;
+
+    /* The following loop copies up to p->nBuffer bytes per iteration into
+    ** the p->aAlloc[] buffer.  */
+    while( nRem>0 ){
+      int rc;                     /* vdbePmaReadBlob() return code */
+      int nCopy;                  /* Number of bytes to copy */
+      u8 *aNext;                  /* Pointer to buffer to copy data from */
+
+      nCopy = nRem;
+      if( nRem>p->nBuffer ) nCopy = p->nBuffer;
+      rc = vdbePmaReadBlob(p, nCopy, &aNext);
+      if( rc!=SQLITE_OK ) return rc;
+      assert( aNext!=p->aAlloc );
+      memcpy(&p->aAlloc[nByte - nRem], aNext, nCopy);
+      nRem -= nCopy;
+    }
+
+    *ppOut = p->aAlloc;
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Read a varint from the stream of data accessed by p. Set *pnOut to
+** the value read.
+*/
+static int vdbePmaReadVarint(PmaReader *p, u64 *pnOut){
+  int iBuf;
+
+  if( p->aMap ){
+    p->iReadOff += sqlite3GetVarint(&p->aMap[p->iReadOff], pnOut);
+  }else{
+    iBuf = p->iReadOff % p->nBuffer;
+    if( iBuf && (p->nBuffer-iBuf)>=9 ){
+      p->iReadOff += sqlite3GetVarint(&p->aBuffer[iBuf], pnOut);
+    }else{
+      u8 aVarint[16], *a;
+      int i = 0, rc;
+      do{
+        rc = vdbePmaReadBlob(p, 1, &a);
+        if( rc ) return rc;
+        aVarint[(i++)&0xf] = a[0];
+      }while( (a[0]&0x80)!=0 );
+      sqlite3GetVarint(aVarint, pnOut);
+    }
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Attempt to memory map file pFile. If successful, set *pp to point to the
+** new mapping and return SQLITE_OK. If the mapping is not attempted 
+** (because the file is too large or the VFS layer is configured not to use
+** mmap), return SQLITE_OK and set *pp to NULL.
+**
+** Or, if an error occurs, return an SQLite error code. The final value of
+** *pp is undefined in this case.
+*/
+static int vdbeSorterMapFile(SortSubtask *pTask, SorterFile *pFile, u8 **pp){
+  int rc = SQLITE_OK;
+  if( pFile->iEof<=(i64)(pTask->pSorter->db->nMaxSorterMmap) ){
+    sqlite3_file *pFd = pFile->pFd;
+    if( pFd->pMethods->iVersion>=3 ){
+      rc = sqlite3OsFetch(pFd, 0, (int)pFile->iEof, (void**)pp);
+      testcase( rc!=SQLITE_OK );
+    }
+  }
+  return rc;
+}
+
+/*
+** Attach PmaReader pReadr to file pFile (if it is not already attached to
+** that file) and seek it to offset iOff within the file.  Return SQLITE_OK 
+** if successful, or an SQLite error code if an error occurs.
+*/
+static int vdbePmaReaderSeek(
+  SortSubtask *pTask,             /* Task context */
+  PmaReader *pReadr,              /* Reader whose cursor is to be moved */
+  SorterFile *pFile,              /* Sorter file to read from */
+  i64 iOff                        /* Offset in pFile */
+){
+  int rc = SQLITE_OK;
+
+  assert( pReadr->pIncr==0 || pReadr->pIncr->bEof==0 );
+
+  if( sqlite3FaultSim(201) ) return SQLITE_IOERR_READ;
+  if( pReadr->aMap ){
+    sqlite3OsUnfetch(pReadr->pFd, 0, pReadr->aMap);
+    pReadr->aMap = 0;
+  }
+  pReadr->iReadOff = iOff;
+  pReadr->iEof = pFile->iEof;
+  pReadr->pFd = pFile->pFd;
+
+  rc = vdbeSorterMapFile(pTask, pFile, &pReadr->aMap);
+  if( rc==SQLITE_OK && pReadr->aMap==0 ){
+    int pgsz = pTask->pSorter->pgsz;
+    int iBuf = pReadr->iReadOff % pgsz;
+    if( pReadr->aBuffer==0 ){
+      pReadr->aBuffer = (u8*)sqlite3Malloc(pgsz);
+      if( pReadr->aBuffer==0 ) rc = SQLITE_NOMEM_BKPT;
+      pReadr->nBuffer = pgsz;
+    }
+    if( rc==SQLITE_OK && iBuf ){
+      int nRead = pgsz - iBuf;
+      if( (pReadr->iReadOff + nRead) > pReadr->iEof ){
+        nRead = (int)(pReadr->iEof - pReadr->iReadOff);
+      }
+      rc = sqlite3OsRead(
+          pReadr->pFd, &pReadr->aBuffer[iBuf], nRead, pReadr->iReadOff
+      );
+      testcase( rc!=SQLITE_OK );
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Advance PmaReader pReadr to the next key in its PMA. Return SQLITE_OK if
+** no error occurs, or an SQLite error code if one does.
+*/
+static int vdbePmaReaderNext(PmaReader *pReadr){
+  int rc = SQLITE_OK;             /* Return Code */
+  u64 nRec = 0;                   /* Size of record in bytes */
+
+
+  if( pReadr->iReadOff>=pReadr->iEof ){
+    IncrMerger *pIncr = pReadr->pIncr;
+    int bEof = 1;
+    if( pIncr ){
+      rc = vdbeIncrSwap(pIncr);
+      if( rc==SQLITE_OK && pIncr->bEof==0 ){
+        rc = vdbePmaReaderSeek(
+            pIncr->pTask, pReadr, &pIncr->aFile[0], pIncr->iStartOff
+        );
+        bEof = 0;
+      }
+    }
+
+    if( bEof ){
+      /* This is an EOF condition */
+      vdbePmaReaderClear(pReadr);
+      testcase( rc!=SQLITE_OK );
+      return rc;
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = vdbePmaReadVarint(pReadr, &nRec);
+  }
+  if( rc==SQLITE_OK ){
+    pReadr->nKey = (int)nRec;
+    rc = vdbePmaReadBlob(pReadr, (int)nRec, &pReadr->aKey);
+    testcase( rc!=SQLITE_OK );
+  }
+
+  return rc;
+}
+
+/*
+** Initialize PmaReader pReadr to scan through the PMA stored in file pFile
+** starting at offset iStart and ending at offset iEof-1. This function 
+** leaves the PmaReader pointing to the first key in the PMA (or EOF if the 
+** PMA is empty).
+**
+** If the pnByte parameter is NULL, then it is assumed that the file 
+** contains a single PMA, and that that PMA omits the initial length varint.
+*/
+static int vdbePmaReaderInit(
+  SortSubtask *pTask,             /* Task context */
+  SorterFile *pFile,              /* Sorter file to read from */
+  i64 iStart,                     /* Start offset in pFile */
+  PmaReader *pReadr,              /* PmaReader to populate */
+  i64 *pnByte                     /* IN/OUT: Increment this value by PMA size */
+){
+  int rc;
+
+  assert( pFile->iEof>iStart );
+  assert( pReadr->aAlloc==0 && pReadr->nAlloc==0 );
+  assert( pReadr->aBuffer==0 );
+  assert( pReadr->aMap==0 );
+
+  rc = vdbePmaReaderSeek(pTask, pReadr, pFile, iStart);
+  if( rc==SQLITE_OK ){
+    u64 nByte = 0;                 /* Size of PMA in bytes */
+    rc = vdbePmaReadVarint(pReadr, &nByte);
+    pReadr->iEof = pReadr->iReadOff + nByte;
+    *pnByte += nByte;
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = vdbePmaReaderNext(pReadr);
+  }
+  return rc;
+}
+
+/*
+** A version of vdbeSorterCompare() that assumes that it has already been
+** determined that the first field of key1 is equal to the first field of 
+** key2.
+*/
+static int vdbeSorterCompareTail(
+  SortSubtask *pTask,             /* Subtask context (for pKeyInfo) */
+  int *pbKey2Cached,              /* True if pTask->pUnpacked is pKey2 */
+  const void *pKey1, int nKey1,   /* Left side of comparison */
+  const void *pKey2, int nKey2    /* Right side of comparison */
+){
+  UnpackedRecord *r2 = pTask->pUnpacked;
+  if( *pbKey2Cached==0 ){
+    sqlite3VdbeRecordUnpack(pTask->pSorter->pKeyInfo, nKey2, pKey2, r2);
+    *pbKey2Cached = 1;
+  }
+  return sqlite3VdbeRecordCompareWithSkip(nKey1, pKey1, r2, 1);
+}
+
+/*
+** Compare key1 (buffer pKey1, size nKey1 bytes) with key2 (buffer pKey2, 
+** size nKey2 bytes). Use (pTask->pKeyInfo) for the collation sequences
+** used by the comparison. Return the result of the comparison.
+**
+** If IN/OUT parameter *pbKey2Cached is true when this function is called,
+** it is assumed that (pTask->pUnpacked) contains the unpacked version
+** of key2. If it is false, (pTask->pUnpacked) is populated with the unpacked
+** version of key2 and *pbKey2Cached set to true before returning.
+**
+** If an OOM error is encountered, (pTask->pUnpacked->error_rc) is set
+** to SQLITE_NOMEM.
+*/
+static int vdbeSorterCompare(
+  SortSubtask *pTask,             /* Subtask context (for pKeyInfo) */
+  int *pbKey2Cached,              /* True if pTask->pUnpacked is pKey2 */
+  const void *pKey1, int nKey1,   /* Left side of comparison */
+  const void *pKey2, int nKey2    /* Right side of comparison */
+){
+  UnpackedRecord *r2 = pTask->pUnpacked;
+  if( !*pbKey2Cached ){
+    sqlite3VdbeRecordUnpack(pTask->pSorter->pKeyInfo, nKey2, pKey2, r2);
+    *pbKey2Cached = 1;
+  }
+  return sqlite3VdbeRecordCompare(nKey1, pKey1, r2);
+}
+
+/*
+** A specially optimized version of vdbeSorterCompare() that assumes that
+** the first field of each key is a TEXT value and that the collation
+** sequence to compare them with is BINARY.
+*/
+static int vdbeSorterCompareText(
+  SortSubtask *pTask,             /* Subtask context (for pKeyInfo) */
+  int *pbKey2Cached,              /* True if pTask->pUnpacked is pKey2 */
+  const void *pKey1, int nKey1,   /* Left side of comparison */
+  const void *pKey2, int nKey2    /* Right side of comparison */
+){
+  const u8 * const p1 = (const u8 * const)pKey1;
+  const u8 * const p2 = (const u8 * const)pKey2;
+  const u8 * const v1 = &p1[ p1[0] ];   /* Pointer to value 1 */
+  const u8 * const v2 = &p2[ p2[0] ];   /* Pointer to value 2 */
+
+  int n1;
+  int n2;
+  int res;
+
+  getVarint32(&p1[1], n1); n1 = (n1 - 13) / 2;
+  getVarint32(&p2[1], n2); n2 = (n2 - 13) / 2;
+  res = memcmp(v1, v2, MIN(n1, n2));
+  if( res==0 ){
+    res = n1 - n2;
+  }
+
+  if( res==0 ){
+    if( pTask->pSorter->pKeyInfo->nField>1 ){
+      res = vdbeSorterCompareTail(
+          pTask, pbKey2Cached, pKey1, nKey1, pKey2, nKey2
+      );
+    }
+  }else{
+    if( pTask->pSorter->pKeyInfo->aSortOrder[0] ){
+      res = res * -1;
+    }
+  }
+
+  return res;
+}
+
+/*
+** A specially optimized version of vdbeSorterCompare() that assumes that
+** the first field of each key is an INTEGER value.
+*/
+static int vdbeSorterCompareInt(
+  SortSubtask *pTask,             /* Subtask context (for pKeyInfo) */
+  int *pbKey2Cached,              /* True if pTask->pUnpacked is pKey2 */
+  const void *pKey1, int nKey1,   /* Left side of comparison */
+  const void *pKey2, int nKey2    /* Right side of comparison */
+){
+  const u8 * const p1 = (const u8 * const)pKey1;
+  const u8 * const p2 = (const u8 * const)pKey2;
+  const int s1 = p1[1];                 /* Left hand serial type */
+  const int s2 = p2[1];                 /* Right hand serial type */
+  const u8 * const v1 = &p1[ p1[0] ];   /* Pointer to value 1 */
+  const u8 * const v2 = &p2[ p2[0] ];   /* Pointer to value 2 */
+  int res;                              /* Return value */
+
+  assert( (s1>0 && s1<7) || s1==8 || s1==9 );
+  assert( (s2>0 && s2<7) || s2==8 || s2==9 );
+
+  if( s1>7 && s2>7 ){
+    res = s1 - s2;
+  }else{
+    if( s1==s2 ){
+      if( (*v1 ^ *v2) & 0x80 ){
+        /* The two values have different signs */
+        res = (*v1 & 0x80) ? -1 : +1;
+      }else{
+        /* The two values have the same sign. Compare using memcmp(). */
+        static const u8 aLen[] = {0, 1, 2, 3, 4, 6, 8 };
+        int i;
+        res = 0;
+        for(i=0; i<aLen[s1]; i++){
+          if( (res = v1[i] - v2[i]) ) break;
+        }
+      }
+    }else{
+      if( s2>7 ){
+        res = +1;
+      }else if( s1>7 ){
+        res = -1;
+      }else{
+        res = s1 - s2;
+      }
+      assert( res!=0 );
+
+      if( res>0 ){
+        if( *v1 & 0x80 ) res = -1;
+      }else{
+        if( *v2 & 0x80 ) res = +1;
+      }
+    }
+  }
+
+  if( res==0 ){
+    if( pTask->pSorter->pKeyInfo->nField>1 ){
+      res = vdbeSorterCompareTail(
+          pTask, pbKey2Cached, pKey1, nKey1, pKey2, nKey2
+      );
+    }
+  }else if( pTask->pSorter->pKeyInfo->aSortOrder[0] ){
+    res = res * -1;
+  }
+
+  return res;
+}
+
+/*
+** Initialize the temporary index cursor just opened as a sorter cursor.
+**
+** Usually, the sorter module uses the value of (pCsr->pKeyInfo->nField)
+** to determine the number of fields that should be compared from the
+** records being sorted. However, if the value passed as argument nField
+** is non-zero and the sorter is able to guarantee a stable sort, nField
+** is used instead. This is used when sorting records for a CREATE INDEX
+** statement. In this case, keys are always delivered to the sorter in
+** order of the primary key, which happens to be make up the final part 
+** of the records being sorted. So if the sort is stable, there is never
+** any reason to compare PK fields and they can be ignored for a small
+** performance boost.
+**
+** The sorter can guarantee a stable sort when running in single-threaded
+** mode, but not in multi-threaded mode.
+**
+** SQLITE_OK is returned if successful, or an SQLite error code otherwise.
+*/
+SQLITE_PRIVATE int sqlite3VdbeSorterInit(
+  sqlite3 *db,                    /* Database connection (for malloc()) */
+  int nField,                     /* Number of key fields in each record */
+  VdbeCursor *pCsr                /* Cursor that holds the new sorter */
+){
+  int pgsz;                       /* Page size of main database */
+  int i;                          /* Used to iterate through aTask[] */
+  VdbeSorter *pSorter;            /* The new sorter */
+  KeyInfo *pKeyInfo;              /* Copy of pCsr->pKeyInfo with db==0 */
+  int szKeyInfo;                  /* Size of pCsr->pKeyInfo in bytes */
+  int sz;                         /* Size of pSorter in bytes */
+  int rc = SQLITE_OK;
+#if SQLITE_MAX_WORKER_THREADS==0
+# define nWorker 0
+#else
+  int nWorker;
+#endif
+
+  /* Initialize the upper limit on the number of worker threads */
+#if SQLITE_MAX_WORKER_THREADS>0
+  if( sqlite3TempInMemory(db) || sqlite3GlobalConfig.bCoreMutex==0 ){
+    nWorker = 0;
+  }else{
+    nWorker = db->aLimit[SQLITE_LIMIT_WORKER_THREADS];
+  }
+#endif
+
+  /* Do not allow the total number of threads (main thread + all workers)
+  ** to exceed the maximum merge count */
+#if SQLITE_MAX_WORKER_THREADS>=SORTER_MAX_MERGE_COUNT
+  if( nWorker>=SORTER_MAX_MERGE_COUNT ){
+    nWorker = SORTER_MAX_MERGE_COUNT-1;
+  }
+#endif
+
+  assert( pCsr->pKeyInfo && pCsr->pBt==0 );
+  assert( pCsr->eCurType==CURTYPE_SORTER );
+  szKeyInfo = sizeof(KeyInfo) + (pCsr->pKeyInfo->nField-1)*sizeof(CollSeq*);
+  sz = sizeof(VdbeSorter) + nWorker * sizeof(SortSubtask);
+
+  pSorter = (VdbeSorter*)sqlite3DbMallocZero(db, sz + szKeyInfo);
+  pCsr->uc.pSorter = pSorter;
+  if( pSorter==0 ){
+    rc = SQLITE_NOMEM_BKPT;
+  }else{
+    pSorter->pKeyInfo = pKeyInfo = (KeyInfo*)((u8*)pSorter + sz);
+    memcpy(pKeyInfo, pCsr->pKeyInfo, szKeyInfo);
+    pKeyInfo->db = 0;
+    if( nField && nWorker==0 ){
+      pKeyInfo->nXField += (pKeyInfo->nField - nField);
+      pKeyInfo->nField = nField;
+    }
+    pSorter->pgsz = pgsz = sqlite3BtreeGetPageSize(db->aDb[0].pBt);
+    pSorter->nTask = nWorker + 1;
+    pSorter->iPrev = (u8)(nWorker - 1);
+    pSorter->bUseThreads = (pSorter->nTask>1);
+    pSorter->db = db;
+    for(i=0; i<pSorter->nTask; i++){
+      SortSubtask *pTask = &pSorter->aTask[i];
+      pTask->pSorter = pSorter;
+    }
+
+    if( !sqlite3TempInMemory(db) ){
+      i64 mxCache;                /* Cache size in bytes*/
+      u32 szPma = sqlite3GlobalConfig.szPma;
+      pSorter->mnPmaSize = szPma * pgsz;
+
+      mxCache = db->aDb[0].pSchema->cache_size;
+      if( mxCache<0 ){
+        /* A negative cache-size value C indicates that the cache is abs(C)
+        ** KiB in size.  */
+        mxCache = mxCache * -1024;
+      }else{
+        mxCache = mxCache * pgsz;
+      }
+      mxCache = MIN(mxCache, SQLITE_MAX_PMASZ);
+      pSorter->mxPmaSize = MAX(pSorter->mnPmaSize, (int)mxCache);
+
+      /* EVIDENCE-OF: R-26747-61719 When the application provides any amount of
+      ** scratch memory using SQLITE_CONFIG_SCRATCH, SQLite avoids unnecessary
+      ** large heap allocations.
+      */
+      if( sqlite3GlobalConfig.pScratch==0 ){
+        assert( pSorter->iMemory==0 );
+        pSorter->nMemory = pgsz;
+        pSorter->list.aMemory = (u8*)sqlite3Malloc(pgsz);
+        if( !pSorter->list.aMemory ) rc = SQLITE_NOMEM_BKPT;
+      }
+    }
+
+    if( (pKeyInfo->nField+pKeyInfo->nXField)<13 
+     && (pKeyInfo->aColl[0]==0 || pKeyInfo->aColl[0]==db->pDfltColl)
+    ){
+      pSorter->typeMask = SORTER_TYPE_INTEGER | SORTER_TYPE_TEXT;
+    }
+  }
+
+  return rc;
+}
+#undef nWorker   /* Defined at the top of this function */
+
+/*
+** Free the list of sorted records starting at pRecord.
+*/
+static void vdbeSorterRecordFree(sqlite3 *db, SorterRecord *pRecord){
+  SorterRecord *p;
+  SorterRecord *pNext;
+  for(p=pRecord; p; p=pNext){
+    pNext = p->u.pNext;
+    sqlite3DbFree(db, p);
+  }
+}
+
+/*
+** Free all resources owned by the object indicated by argument pTask. All 
+** fields of *pTask are zeroed before returning.
+*/
+static void vdbeSortSubtaskCleanup(sqlite3 *db, SortSubtask *pTask){
+  sqlite3DbFree(db, pTask->pUnpacked);
+#if SQLITE_MAX_WORKER_THREADS>0
+  /* pTask->list.aMemory can only be non-zero if it was handed memory
+  ** from the main thread.  That only occurs SQLITE_MAX_WORKER_THREADS>0 */
+  if( pTask->list.aMemory ){
+    sqlite3_free(pTask->list.aMemory);
+  }else
+#endif
+  {
+    assert( pTask->list.aMemory==0 );
+    vdbeSorterRecordFree(0, pTask->list.pList);
+  }
+  if( pTask->file.pFd ){
+    sqlite3OsCloseFree(pTask->file.pFd);
+  }
+  if( pTask->file2.pFd ){
+    sqlite3OsCloseFree(pTask->file2.pFd);
+  }
+  memset(pTask, 0, sizeof(SortSubtask));
+}
+
+#ifdef SQLITE_DEBUG_SORTER_THREADS
+static void vdbeSorterWorkDebug(SortSubtask *pTask, const char *zEvent){
+  i64 t;
+  int iTask = (pTask - pTask->pSorter->aTask);
+  sqlite3OsCurrentTimeInt64(pTask->pSorter->db->pVfs, &t);
+  fprintf(stderr, "%lld:%d %s\n", t, iTask, zEvent);
+}
+static void vdbeSorterRewindDebug(const char *zEvent){
+  i64 t;
+  sqlite3OsCurrentTimeInt64(sqlite3_vfs_find(0), &t);
+  fprintf(stderr, "%lld:X %s\n", t, zEvent);
+}
+static void vdbeSorterPopulateDebug(
+  SortSubtask *pTask,
+  const char *zEvent
+){
+  i64 t;
+  int iTask = (pTask - pTask->pSorter->aTask);
+  sqlite3OsCurrentTimeInt64(pTask->pSorter->db->pVfs, &t);
+  fprintf(stderr, "%lld:bg%d %s\n", t, iTask, zEvent);
+}
+static void vdbeSorterBlockDebug(
+  SortSubtask *pTask,
+  int bBlocked,
+  const char *zEvent
+){
+  if( bBlocked ){
+    i64 t;
+    sqlite3OsCurrentTimeInt64(pTask->pSorter->db->pVfs, &t);
+    fprintf(stderr, "%lld:main %s\n", t, zEvent);
+  }
+}
+#else
+# define vdbeSorterWorkDebug(x,y)
+# define vdbeSorterRewindDebug(y)
+# define vdbeSorterPopulateDebug(x,y)
+# define vdbeSorterBlockDebug(x,y,z)
+#endif
+
+#if SQLITE_MAX_WORKER_THREADS>0
+/*
+** Join thread pTask->thread.
+*/
+static int vdbeSorterJoinThread(SortSubtask *pTask){
+  int rc = SQLITE_OK;
+  if( pTask->pThread ){
+#ifdef SQLITE_DEBUG_SORTER_THREADS
+    int bDone = pTask->bDone;
+#endif
+    void *pRet = SQLITE_INT_TO_PTR(SQLITE_ERROR);
+    vdbeSorterBlockDebug(pTask, !bDone, "enter");
+    (void)sqlite3ThreadJoin(pTask->pThread, &pRet);
+    vdbeSorterBlockDebug(pTask, !bDone, "exit");
+    rc = SQLITE_PTR_TO_INT(pRet);
+    assert( pTask->bDone==1 );
+    pTask->bDone = 0;
+    pTask->pThread = 0;
+  }
+  return rc;
+}
+
+/*
+** Launch a background thread to run xTask(pIn).
+*/
+static int vdbeSorterCreateThread(
+  SortSubtask *pTask,             /* Thread will use this task object */
+  void *(*xTask)(void*),          /* Routine to run in a separate thread */
+  void *pIn                       /* Argument passed into xTask() */
+){
+  assert( pTask->pThread==0 && pTask->bDone==0 );
+  return sqlite3ThreadCreate(&pTask->pThread, xTask, pIn);
+}
+
+/*
+** Join all outstanding threads launched by SorterWrite() to create 
+** level-0 PMAs.
+*/
+static int vdbeSorterJoinAll(VdbeSorter *pSorter, int rcin){
+  int rc = rcin;
+  int i;
+
+  /* This function is always called by the main user thread.
+  **
+  ** If this function is being called after SorterRewind() has been called, 
+  ** it is possible that thread pSorter->aTask[pSorter->nTask-1].pThread
+  ** is currently attempt to join one of the other threads. To avoid a race
+  ** condition where this thread also attempts to join the same object, join 
+  ** thread pSorter->aTask[pSorter->nTask-1].pThread first. */
+  for(i=pSorter->nTask-1; i>=0; i--){
+    SortSubtask *pTask = &pSorter->aTask[i];
+    int rc2 = vdbeSorterJoinThread(pTask);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }
+  return rc;
+}
+#else
+# define vdbeSorterJoinAll(x,rcin) (rcin)
+# define vdbeSorterJoinThread(pTask) SQLITE_OK
+#endif
+
+/*
+** Allocate a new MergeEngine object capable of handling up to
+** nReader PmaReader inputs.
+**
+** nReader is automatically rounded up to the next power of two.
+** nReader may not exceed SORTER_MAX_MERGE_COUNT even after rounding up.
+*/
+static MergeEngine *vdbeMergeEngineNew(int nReader){
+  int N = 2;                      /* Smallest power of two >= nReader */
+  int nByte;                      /* Total bytes of space to allocate */
+  MergeEngine *pNew;              /* Pointer to allocated object to return */
+
+  assert( nReader<=SORTER_MAX_MERGE_COUNT );
+
+  while( N<nReader ) N += N;
+  nByte = sizeof(MergeEngine) + N * (sizeof(int) + sizeof(PmaReader));
+
+  pNew = sqlite3FaultSim(100) ? 0 : (MergeEngine*)sqlite3MallocZero(nByte);
+  if( pNew ){
+    pNew->nTree = N;
+    pNew->pTask = 0;
+    pNew->aReadr = (PmaReader*)&pNew[1];
+    pNew->aTree = (int*)&pNew->aReadr[N];
+  }
+  return pNew;
+}
+
+/*
+** Free the MergeEngine object passed as the only argument.
+*/
+static void vdbeMergeEngineFree(MergeEngine *pMerger){
+  int i;
+  if( pMerger ){
+    for(i=0; i<pMerger->nTree; i++){
+      vdbePmaReaderClear(&pMerger->aReadr[i]);
+    }
+  }
+  sqlite3_free(pMerger);
+}
+
+/*
+** Free all resources associated with the IncrMerger object indicated by
+** the first argument.
+*/
+static void vdbeIncrFree(IncrMerger *pIncr){
+  if( pIncr ){
+#if SQLITE_MAX_WORKER_THREADS>0
+    if( pIncr->bUseThread ){
+      vdbeSorterJoinThread(pIncr->pTask);
+      if( pIncr->aFile[0].pFd ) sqlite3OsCloseFree(pIncr->aFile[0].pFd);
+      if( pIncr->aFile[1].pFd ) sqlite3OsCloseFree(pIncr->aFile[1].pFd);
+    }
+#endif
+    vdbeMergeEngineFree(pIncr->pMerger);
+    sqlite3_free(pIncr);
+  }
+}
+
+/*
+** Reset a sorting cursor back to its original empty state.
+*/
+SQLITE_PRIVATE void sqlite3VdbeSorterReset(sqlite3 *db, VdbeSorter *pSorter){
+  int i;
+  (void)vdbeSorterJoinAll(pSorter, SQLITE_OK);
+  assert( pSorter->bUseThreads || pSorter->pReader==0 );
+#if SQLITE_MAX_WORKER_THREADS>0
+  if( pSorter->pReader ){
+    vdbePmaReaderClear(pSorter->pReader);
+    sqlite3DbFree(db, pSorter->pReader);
+    pSorter->pReader = 0;
+  }
+#endif
+  vdbeMergeEngineFree(pSorter->pMerger);
+  pSorter->pMerger = 0;
+  for(i=0; i<pSorter->nTask; i++){
+    SortSubtask *pTask = &pSorter->aTask[i];
+    vdbeSortSubtaskCleanup(db, pTask);
+    pTask->pSorter = pSorter;
+  }
+  if( pSorter->list.aMemory==0 ){
+    vdbeSorterRecordFree(0, pSorter->list.pList);
+  }
+  pSorter->list.pList = 0;
+  pSorter->list.szPMA = 0;
+  pSorter->bUsePMA = 0;
+  pSorter->iMemory = 0;
+  pSorter->mxKeysize = 0;
+  sqlite3DbFree(db, pSorter->pUnpacked);
+  pSorter->pUnpacked = 0;
+}
+
+/*
+** Free any cursor components allocated by sqlite3VdbeSorterXXX routines.
+*/
+SQLITE_PRIVATE void sqlite3VdbeSorterClose(sqlite3 *db, VdbeCursor *pCsr){
+  VdbeSorter *pSorter;
+  assert( pCsr->eCurType==CURTYPE_SORTER );
+  pSorter = pCsr->uc.pSorter;
+  if( pSorter ){
+    sqlite3VdbeSorterReset(db, pSorter);
+    sqlite3_free(pSorter->list.aMemory);
+    sqlite3DbFree(db, pSorter);
+    pCsr->uc.pSorter = 0;
+  }
+}
+
+#if SQLITE_MAX_MMAP_SIZE>0
+/*
+** The first argument is a file-handle open on a temporary file. The file
+** is guaranteed to be nByte bytes or smaller in size. This function
+** attempts to extend the file to nByte bytes in size and to ensure that
+** the VFS has memory mapped it.
+**
+** Whether or not the file does end up memory mapped of course depends on
+** the specific VFS implementation.
+*/
+static void vdbeSorterExtendFile(sqlite3 *db, sqlite3_file *pFd, i64 nByte){
+  if( nByte<=(i64)(db->nMaxSorterMmap) && pFd->pMethods->iVersion>=3 ){
+    void *p = 0;
+    int chunksize = 4*1024;
+    sqlite3OsFileControlHint(pFd, SQLITE_FCNTL_CHUNK_SIZE, &chunksize);
+    sqlite3OsFileControlHint(pFd, SQLITE_FCNTL_SIZE_HINT, &nByte);
+    sqlite3OsFetch(pFd, 0, (int)nByte, &p);
+    sqlite3OsUnfetch(pFd, 0, p);
+  }
+}
+#else
+# define vdbeSorterExtendFile(x,y,z)
+#endif
+
+/*
+** Allocate space for a file-handle and open a temporary file. If successful,
+** set *ppFd to point to the malloc'd file-handle and return SQLITE_OK.
+** Otherwise, set *ppFd to 0 and return an SQLite error code.
+*/
+static int vdbeSorterOpenTempFile(
+  sqlite3 *db,                    /* Database handle doing sort */
+  i64 nExtend,                    /* Attempt to extend file to this size */
+  sqlite3_file **ppFd
+){
+  int rc;
+  if( sqlite3FaultSim(202) ) return SQLITE_IOERR_ACCESS;
+  rc = sqlite3OsOpenMalloc(db->pVfs, 0, ppFd,
+      SQLITE_OPEN_TEMP_JOURNAL |
+      SQLITE_OPEN_READWRITE    | SQLITE_OPEN_CREATE |
+      SQLITE_OPEN_EXCLUSIVE    | SQLITE_OPEN_DELETEONCLOSE, &rc
+  );
+  if( rc==SQLITE_OK ){
+    i64 max = SQLITE_MAX_MMAP_SIZE;
+    sqlite3OsFileControlHint(*ppFd, SQLITE_FCNTL_MMAP_SIZE, (void*)&max);
+    if( nExtend>0 ){
+      vdbeSorterExtendFile(db, *ppFd, nExtend);
+    }
+  }
+  return rc;
+}
+
+/*
+** If it has not already been allocated, allocate the UnpackedRecord 
+** structure at pTask->pUnpacked. Return SQLITE_OK if successful (or 
+** if no allocation was required), or SQLITE_NOMEM otherwise.
+*/
+static int vdbeSortAllocUnpacked(SortSubtask *pTask){
+  if( pTask->pUnpacked==0 ){
+    char *pFree;
+    pTask->pUnpacked = sqlite3VdbeAllocUnpackedRecord(
+        pTask->pSorter->pKeyInfo, 0, 0, &pFree
+    );
+    assert( pTask->pUnpacked==(UnpackedRecord*)pFree );
+    if( pFree==0 ) return SQLITE_NOMEM_BKPT;
+    pTask->pUnpacked->nField = pTask->pSorter->pKeyInfo->nField;
+    pTask->pUnpacked->errCode = 0;
+  }
+  return SQLITE_OK;
+}
+
+
+/*
+** Merge the two sorted lists p1 and p2 into a single list.
+*/
+static SorterRecord *vdbeSorterMerge(
+  SortSubtask *pTask,             /* Calling thread context */
+  SorterRecord *p1,               /* First list to merge */
+  SorterRecord *p2                /* Second list to merge */
+){
+  SorterRecord *pFinal = 0;
+  SorterRecord **pp = &pFinal;
+  int bCached = 0;
+
+  assert( p1!=0 && p2!=0 );
+  for(;;){
+    int res;
+    res = pTask->xCompare(
+        pTask, &bCached, SRVAL(p1), p1->nVal, SRVAL(p2), p2->nVal
+    );
+
+    if( res<=0 ){
+      *pp = p1;
+      pp = &p1->u.pNext;
+      p1 = p1->u.pNext;
+      if( p1==0 ){
+        *pp = p2;
+        break;
+      }
+    }else{
+      *pp = p2;
+      pp = &p2->u.pNext;
+      p2 = p2->u.pNext;
+      bCached = 0;
+      if( p2==0 ){
+        *pp = p1;
+        break;
+      }
+    }
+  }
+  return pFinal;
+}
+
+/*
+** Return the SorterCompare function to compare values collected by the
+** sorter object passed as the only argument.
+*/
+static SorterCompare vdbeSorterGetCompare(VdbeSorter *p){
+  if( p->typeMask==SORTER_TYPE_INTEGER ){
+    return vdbeSorterCompareInt;
+  }else if( p->typeMask==SORTER_TYPE_TEXT ){
+    return vdbeSorterCompareText; 
+  }
+  return vdbeSorterCompare;
+}
+
+/*
+** Sort the linked list of records headed at pTask->pList. Return 
+** SQLITE_OK if successful, or an SQLite error code (i.e. SQLITE_NOMEM) if 
+** an error occurs.
+*/
+static int vdbeSorterSort(SortSubtask *pTask, SorterList *pList){
+  int i;
+  SorterRecord **aSlot;
+  SorterRecord *p;
+  int rc;
+
+  rc = vdbeSortAllocUnpacked(pTask);
+  if( rc!=SQLITE_OK ) return rc;
+
+  p = pList->pList;
+  pTask->xCompare = vdbeSorterGetCompare(pTask->pSorter);
+
+  aSlot = (SorterRecord **)sqlite3MallocZero(64 * sizeof(SorterRecord *));
+  if( !aSlot ){
+    return SQLITE_NOMEM_BKPT;
+  }
+
+  while( p ){
+    SorterRecord *pNext;
+    if( pList->aMemory ){
+      if( (u8*)p==pList->aMemory ){
+        pNext = 0;
+      }else{
+        assert( p->u.iNext<sqlite3MallocSize(pList->aMemory) );
+        pNext = (SorterRecord*)&pList->aMemory[p->u.iNext];
+      }
+    }else{
+      pNext = p->u.pNext;
+    }
+
+    p->u.pNext = 0;
+    for(i=0; aSlot[i]; i++){
+      p = vdbeSorterMerge(pTask, p, aSlot[i]);
+      aSlot[i] = 0;
+    }
+    aSlot[i] = p;
+    p = pNext;
+  }
+
+  p = 0;
+  for(i=0; i<64; i++){
+    if( aSlot[i]==0 ) continue;
+    p = p ? vdbeSorterMerge(pTask, p, aSlot[i]) : aSlot[i];
+  }
+  pList->pList = p;
+
+  sqlite3_free(aSlot);
+  assert( pTask->pUnpacked->errCode==SQLITE_OK 
+       || pTask->pUnpacked->errCode==SQLITE_NOMEM 
+  );
+  return pTask->pUnpacked->errCode;
+}
+
+/*
+** Initialize a PMA-writer object.
+*/
+static void vdbePmaWriterInit(
+  sqlite3_file *pFd,              /* File handle to write to */
+  PmaWriter *p,                   /* Object to populate */
+  int nBuf,                       /* Buffer size */
+  i64 iStart                      /* Offset of pFd to begin writing at */
+){
+  memset(p, 0, sizeof(PmaWriter));
+  p->aBuffer = (u8*)sqlite3Malloc(nBuf);
+  if( !p->aBuffer ){
+    p->eFWErr = SQLITE_NOMEM_BKPT;
+  }else{
+    p->iBufEnd = p->iBufStart = (iStart % nBuf);
+    p->iWriteOff = iStart - p->iBufStart;
+    p->nBuffer = nBuf;
+    p->pFd = pFd;
+  }
+}
+
+/*
+** Write nData bytes of data to the PMA. Return SQLITE_OK
+** if successful, or an SQLite error code if an error occurs.
+*/
+static void vdbePmaWriteBlob(PmaWriter *p, u8 *pData, int nData){
+  int nRem = nData;
+  while( nRem>0 && p->eFWErr==0 ){
+    int nCopy = nRem;
+    if( nCopy>(p->nBuffer - p->iBufEnd) ){
+      nCopy = p->nBuffer - p->iBufEnd;
+    }
+
+    memcpy(&p->aBuffer[p->iBufEnd], &pData[nData-nRem], nCopy);
+    p->iBufEnd += nCopy;
+    if( p->iBufEnd==p->nBuffer ){
+      p->eFWErr = sqlite3OsWrite(p->pFd, 
+          &p->aBuffer[p->iBufStart], p->iBufEnd - p->iBufStart, 
+          p->iWriteOff + p->iBufStart
+      );
+      p->iBufStart = p->iBufEnd = 0;
+      p->iWriteOff += p->nBuffer;
+    }
+    assert( p->iBufEnd<p->nBuffer );
+
+    nRem -= nCopy;
+  }
+}
+
+/*
+** Flush any buffered data to disk and clean up the PMA-writer object.
+** The results of using the PMA-writer after this call are undefined.
+** Return SQLITE_OK if flushing the buffered data succeeds or is not 
+** required. Otherwise, return an SQLite error code.
+**
+** Before returning, set *piEof to the offset immediately following the
+** last byte written to the file.
+*/
+static int vdbePmaWriterFinish(PmaWriter *p, i64 *piEof){
+  int rc;
+  if( p->eFWErr==0 && ALWAYS(p->aBuffer) && p->iBufEnd>p->iBufStart ){
+    p->eFWErr = sqlite3OsWrite(p->pFd, 
+        &p->aBuffer[p->iBufStart], p->iBufEnd - p->iBufStart, 
+        p->iWriteOff + p->iBufStart
+    );
+  }
+  *piEof = (p->iWriteOff + p->iBufEnd);
+  sqlite3_free(p->aBuffer);
+  rc = p->eFWErr;
+  memset(p, 0, sizeof(PmaWriter));
+  return rc;
+}
+
+/*
+** Write value iVal encoded as a varint to the PMA. Return 
+** SQLITE_OK if successful, or an SQLite error code if an error occurs.
+*/
+static void vdbePmaWriteVarint(PmaWriter *p, u64 iVal){
+  int nByte; 
+  u8 aByte[10];
+  nByte = sqlite3PutVarint(aByte, iVal);
+  vdbePmaWriteBlob(p, aByte, nByte);
+}
+
+/*
+** Write the current contents of in-memory linked-list pList to a level-0
+** PMA in the temp file belonging to sub-task pTask. Return SQLITE_OK if 
+** successful, or an SQLite error code otherwise.
+**
+** The format of a PMA is:
+**
+**     * A varint. This varint contains the total number of bytes of content
+**       in the PMA (not including the varint itself).
+**
+**     * One or more records packed end-to-end in order of ascending keys. 
+**       Each record consists of a varint followed by a blob of data (the 
+**       key). The varint is the number of bytes in the blob of data.
+*/
+static int vdbeSorterListToPMA(SortSubtask *pTask, SorterList *pList){
+  sqlite3 *db = pTask->pSorter->db;
+  int rc = SQLITE_OK;             /* Return code */
+  PmaWriter writer;               /* Object used to write to the file */
+
+#ifdef SQLITE_DEBUG
+  /* Set iSz to the expected size of file pTask->file after writing the PMA. 
+  ** This is used by an assert() statement at the end of this function.  */
+  i64 iSz = pList->szPMA + sqlite3VarintLen(pList->szPMA) + pTask->file.iEof;
+#endif
+
+  vdbeSorterWorkDebug(pTask, "enter");
+  memset(&writer, 0, sizeof(PmaWriter));
+  assert( pList->szPMA>0 );
+
+  /* If the first temporary PMA file has not been opened, open it now. */
+  if( pTask->file.pFd==0 ){
+    rc = vdbeSorterOpenTempFile(db, 0, &pTask->file.pFd);
+    assert( rc!=SQLITE_OK || pTask->file.pFd );
+    assert( pTask->file.iEof==0 );
+    assert( pTask->nPMA==0 );
+  }
+
+  /* Try to get the file to memory map */
+  if( rc==SQLITE_OK ){
+    vdbeSorterExtendFile(db, pTask->file.pFd, pTask->file.iEof+pList->szPMA+9);
+  }
+
+  /* Sort the list */
+  if( rc==SQLITE_OK ){
+    rc = vdbeSorterSort(pTask, pList);
+  }
+
+  if( rc==SQLITE_OK ){
+    SorterRecord *p;
+    SorterRecord *pNext = 0;
+
+    vdbePmaWriterInit(pTask->file.pFd, &writer, pTask->pSorter->pgsz,
+                      pTask->file.iEof);
+    pTask->nPMA++;
+    vdbePmaWriteVarint(&writer, pList->szPMA);
+    for(p=pList->pList; p; p=pNext){
+      pNext = p->u.pNext;
+      vdbePmaWriteVarint(&writer, p->nVal);
+      vdbePmaWriteBlob(&writer, SRVAL(p), p->nVal);
+      if( pList->aMemory==0 ) sqlite3_free(p);
+    }
+    pList->pList = p;
+    rc = vdbePmaWriterFinish(&writer, &pTask->file.iEof);
+  }
+
+  vdbeSorterWorkDebug(pTask, "exit");
+  assert( rc!=SQLITE_OK || pList->pList==0 );
+  assert( rc!=SQLITE_OK || pTask->file.iEof==iSz );
+  return rc;
+}
+
+/*
+** Advance the MergeEngine to its next entry.
+** Set *pbEof to true there is no next entry because
+** the MergeEngine has reached the end of all its inputs.
+**
+** Return SQLITE_OK if successful or an error code if an error occurs.
+*/
+static int vdbeMergeEngineStep(
+  MergeEngine *pMerger,      /* The merge engine to advance to the next row */
+  int *pbEof                 /* Set TRUE at EOF.  Set false for more content */
+){
+  int rc;
+  int iPrev = pMerger->aTree[1];/* Index of PmaReader to advance */
+  SortSubtask *pTask = pMerger->pTask;
+
+  /* Advance the current PmaReader */
+  rc = vdbePmaReaderNext(&pMerger->aReadr[iPrev]);
+
+  /* Update contents of aTree[] */
+  if( rc==SQLITE_OK ){
+    int i;                      /* Index of aTree[] to recalculate */
+    PmaReader *pReadr1;         /* First PmaReader to compare */
+    PmaReader *pReadr2;         /* Second PmaReader to compare */
+    int bCached = 0;
+
+    /* Find the first two PmaReaders to compare. The one that was just
+    ** advanced (iPrev) and the one next to it in the array.  */
+    pReadr1 = &pMerger->aReadr[(iPrev & 0xFFFE)];
+    pReadr2 = &pMerger->aReadr[(iPrev | 0x0001)];
+
+    for(i=(pMerger->nTree+iPrev)/2; i>0; i=i/2){
+      /* Compare pReadr1 and pReadr2. Store the result in variable iRes. */
+      int iRes;
+      if( pReadr1->pFd==0 ){
+        iRes = +1;
+      }else if( pReadr2->pFd==0 ){
+        iRes = -1;
+      }else{
+        iRes = pTask->xCompare(pTask, &bCached,
+            pReadr1->aKey, pReadr1->nKey, pReadr2->aKey, pReadr2->nKey
+        );
+      }
+
+      /* If pReadr1 contained the smaller value, set aTree[i] to its index.
+      ** Then set pReadr2 to the next PmaReader to compare to pReadr1. In this
+      ** case there is no cache of pReadr2 in pTask->pUnpacked, so set
+      ** pKey2 to point to the record belonging to pReadr2.
+      **
+      ** Alternatively, if pReadr2 contains the smaller of the two values,
+      ** set aTree[i] to its index and update pReadr1. If vdbeSorterCompare()
+      ** was actually called above, then pTask->pUnpacked now contains
+      ** a value equivalent to pReadr2. So set pKey2 to NULL to prevent
+      ** vdbeSorterCompare() from decoding pReadr2 again.
+      **
+      ** If the two values were equal, then the value from the oldest
+      ** PMA should be considered smaller. The VdbeSorter.aReadr[] array
+      ** is sorted from oldest to newest, so pReadr1 contains older values
+      ** than pReadr2 iff (pReadr1<pReadr2).  */
+      if( iRes<0 || (iRes==0 && pReadr1<pReadr2) ){
+        pMerger->aTree[i] = (int)(pReadr1 - pMerger->aReadr);
+        pReadr2 = &pMerger->aReadr[ pMerger->aTree[i ^ 0x0001] ];
+        bCached = 0;
+      }else{
+        if( pReadr1->pFd ) bCached = 0;
+        pMerger->aTree[i] = (int)(pReadr2 - pMerger->aReadr);
+        pReadr1 = &pMerger->aReadr[ pMerger->aTree[i ^ 0x0001] ];
+      }
+    }
+    *pbEof = (pMerger->aReadr[pMerger->aTree[1]].pFd==0);
+  }
+
+  return (rc==SQLITE_OK ? pTask->pUnpacked->errCode : rc);
+}
+
+#if SQLITE_MAX_WORKER_THREADS>0
+/*
+** The main routine for background threads that write level-0 PMAs.
+*/
+static void *vdbeSorterFlushThread(void *pCtx){
+  SortSubtask *pTask = (SortSubtask*)pCtx;
+  int rc;                         /* Return code */
+  assert( pTask->bDone==0 );
+  rc = vdbeSorterListToPMA(pTask, &pTask->list);
+  pTask->bDone = 1;
+  return SQLITE_INT_TO_PTR(rc);
+}
+#endif /* SQLITE_MAX_WORKER_THREADS>0 */
+
+/*
+** Flush the current contents of VdbeSorter.list to a new PMA, possibly
+** using a background thread.
+*/
+static int vdbeSorterFlushPMA(VdbeSorter *pSorter){
+#if SQLITE_MAX_WORKER_THREADS==0
+  pSorter->bUsePMA = 1;
+  return vdbeSorterListToPMA(&pSorter->aTask[0], &pSorter->list);
+#else
+  int rc = SQLITE_OK;
+  int i;
+  SortSubtask *pTask = 0;    /* Thread context used to create new PMA */
+  int nWorker = (pSorter->nTask-1);
+
+  /* Set the flag to indicate that at least one PMA has been written. 
+  ** Or will be, anyhow.  */
+  pSorter->bUsePMA = 1;
+
+  /* Select a sub-task to sort and flush the current list of in-memory
+  ** records to disk. If the sorter is running in multi-threaded mode,
+  ** round-robin between the first (pSorter->nTask-1) tasks. Except, if
+  ** the background thread from a sub-tasks previous turn is still running,
+  ** skip it. If the first (pSorter->nTask-1) sub-tasks are all still busy,
+  ** fall back to using the final sub-task. The first (pSorter->nTask-1)
+  ** sub-tasks are prefered as they use background threads - the final 
+  ** sub-task uses the main thread. */
+  for(i=0; i<nWorker; i++){
+    int iTest = (pSorter->iPrev + i + 1) % nWorker;
+    pTask = &pSorter->aTask[iTest];
+    if( pTask->bDone ){
+      rc = vdbeSorterJoinThread(pTask);
+    }
+    if( rc!=SQLITE_OK || pTask->pThread==0 ) break;
+  }
+
+  if( rc==SQLITE_OK ){
+    if( i==nWorker ){
+      /* Use the foreground thread for this operation */
+      rc = vdbeSorterListToPMA(&pSorter->aTask[nWorker], &pSorter->list);
+    }else{
+      /* Launch a background thread for this operation */
+      u8 *aMem = pTask->list.aMemory;
+      void *pCtx = (void*)pTask;
+
+      assert( pTask->pThread==0 && pTask->bDone==0 );
+      assert( pTask->list.pList==0 );
+      assert( pTask->list.aMemory==0 || pSorter->list.aMemory!=0 );
+
+      pSorter->iPrev = (u8)(pTask - pSorter->aTask);
+      pTask->list = pSorter->list;
+      pSorter->list.pList = 0;
+      pSorter->list.szPMA = 0;
+      if( aMem ){
+        pSorter->list.aMemory = aMem;
+        pSorter->nMemory = sqlite3MallocSize(aMem);
+      }else if( pSorter->list.aMemory ){
+        pSorter->list.aMemory = sqlite3Malloc(pSorter->nMemory);
+        if( !pSorter->list.aMemory ) return SQLITE_NOMEM_BKPT;
+      }
+
+      rc = vdbeSorterCreateThread(pTask, vdbeSorterFlushThread, pCtx);
+    }
+  }
+
+  return rc;
+#endif /* SQLITE_MAX_WORKER_THREADS!=0 */
+}
+
+/*
+** Add a record to the sorter.
+*/
+SQLITE_PRIVATE int sqlite3VdbeSorterWrite(
+  const VdbeCursor *pCsr,         /* Sorter cursor */
+  Mem *pVal                       /* Memory cell containing record */
+){
+  VdbeSorter *pSorter;
+  int rc = SQLITE_OK;             /* Return Code */
+  SorterRecord *pNew;             /* New list element */
+  int bFlush;                     /* True to flush contents of memory to PMA */
+  int nReq;                       /* Bytes of memory required */
+  int nPMA;                       /* Bytes of PMA space required */
+  int t;                          /* serial type of first record field */
+
+  assert( pCsr->eCurType==CURTYPE_SORTER );
+  pSorter = pCsr->uc.pSorter;
+  getVarint32((const u8*)&pVal->z[1], t);
+  if( t>0 && t<10 && t!=7 ){
+    pSorter->typeMask &= SORTER_TYPE_INTEGER;
+  }else if( t>10 && (t & 0x01) ){
+    pSorter->typeMask &= SORTER_TYPE_TEXT;
+  }else{
+    pSorter->typeMask = 0;
+  }
+
+  assert( pSorter );
+
+  /* Figure out whether or not the current contents of memory should be
+  ** flushed to a PMA before continuing. If so, do so.
+  **
+  ** If using the single large allocation mode (pSorter->aMemory!=0), then
+  ** flush the contents of memory to a new PMA if (a) at least one value is
+  ** already in memory and (b) the new value will not fit in memory.
+  ** 
+  ** Or, if using separate allocations for each record, flush the contents
+  ** of memory to a PMA if either of the following are true:
+  **
+  **   * The total memory allocated for the in-memory list is greater 
+  **     than (page-size * cache-size), or
+  **
+  **   * The total memory allocated for the in-memory list is greater 
+  **     than (page-size * 10) and sqlite3HeapNearlyFull() returns true.
+  */
+  nReq = pVal->n + sizeof(SorterRecord);
+  nPMA = pVal->n + sqlite3VarintLen(pVal->n);
+  if( pSorter->mxPmaSize ){
+    if( pSorter->list.aMemory ){
+      bFlush = pSorter->iMemory && (pSorter->iMemory+nReq) > pSorter->mxPmaSize;
+    }else{
+      bFlush = (
+          (pSorter->list.szPMA > pSorter->mxPmaSize)
+       || (pSorter->list.szPMA > pSorter->mnPmaSize && sqlite3HeapNearlyFull())
+      );
+    }
+    if( bFlush ){
+      rc = vdbeSorterFlushPMA(pSorter);
+      pSorter->list.szPMA = 0;
+      pSorter->iMemory = 0;
+      assert( rc!=SQLITE_OK || pSorter->list.pList==0 );
+    }
+  }
+
+  pSorter->list.szPMA += nPMA;
+  if( nPMA>pSorter->mxKeysize ){
+    pSorter->mxKeysize = nPMA;
+  }
+
+  if( pSorter->list.aMemory ){
+    int nMin = pSorter->iMemory + nReq;
+
+    if( nMin>pSorter->nMemory ){
+      u8 *aNew;
+      int iListOff = (u8*)pSorter->list.pList - pSorter->list.aMemory;
+      int nNew = pSorter->nMemory * 2;
+      while( nNew < nMin ) nNew = nNew*2;
+      if( nNew > pSorter->mxPmaSize ) nNew = pSorter->mxPmaSize;
+      if( nNew < nMin ) nNew = nMin;
+
+      aNew = sqlite3Realloc(pSorter->list.aMemory, nNew);
+      if( !aNew ) return SQLITE_NOMEM_BKPT;
+      pSorter->list.pList = (SorterRecord*)&aNew[iListOff];
+      pSorter->list.aMemory = aNew;
+      pSorter->nMemory = nNew;
+    }
+
+    pNew = (SorterRecord*)&pSorter->list.aMemory[pSorter->iMemory];
+    pSorter->iMemory += ROUND8(nReq);
+    if( pSorter->list.pList ){
+      pNew->u.iNext = (int)((u8*)(pSorter->list.pList) - pSorter->list.aMemory);
+    }
+  }else{
+    pNew = (SorterRecord *)sqlite3Malloc(nReq);
+    if( pNew==0 ){
+      return SQLITE_NOMEM_BKPT;
+    }
+    pNew->u.pNext = pSorter->list.pList;
+  }
+
+  memcpy(SRVAL(pNew), pVal->z, pVal->n);
+  pNew->nVal = pVal->n;
+  pSorter->list.pList = pNew;
+
+  return rc;
+}
+
+/*
+** Read keys from pIncr->pMerger and populate pIncr->aFile[1]. The format
+** of the data stored in aFile[1] is the same as that used by regular PMAs,
+** except that the number-of-bytes varint is omitted from the start.
+*/
+static int vdbeIncrPopulate(IncrMerger *pIncr){
+  int rc = SQLITE_OK;
+  int rc2;
+  i64 iStart = pIncr->iStartOff;
+  SorterFile *pOut = &pIncr->aFile[1];
+  SortSubtask *pTask = pIncr->pTask;
+  MergeEngine *pMerger = pIncr->pMerger;
+  PmaWriter writer;
+  assert( pIncr->bEof==0 );
+
+  vdbeSorterPopulateDebug(pTask, "enter");
+
+  vdbePmaWriterInit(pOut->pFd, &writer, pTask->pSorter->pgsz, iStart);
+  while( rc==SQLITE_OK ){
+    int dummy;
+    PmaReader *pReader = &pMerger->aReadr[ pMerger->aTree[1] ];
+    int nKey = pReader->nKey;
+    i64 iEof = writer.iWriteOff + writer.iBufEnd;
+
+    /* Check if the output file is full or if the input has been exhausted.
+    ** In either case exit the loop. */
+    if( pReader->pFd==0 ) break;
+    if( (iEof + nKey + sqlite3VarintLen(nKey))>(iStart + pIncr->mxSz) ) break;
+
+    /* Write the next key to the output. */
+    vdbePmaWriteVarint(&writer, nKey);
+    vdbePmaWriteBlob(&writer, pReader->aKey, nKey);
+    assert( pIncr->pMerger->pTask==pTask );
+    rc = vdbeMergeEngineStep(pIncr->pMerger, &dummy);
+  }
+
+  rc2 = vdbePmaWriterFinish(&writer, &pOut->iEof);
+  if( rc==SQLITE_OK ) rc = rc2;
+  vdbeSorterPopulateDebug(pTask, "exit");
+  return rc;
+}
+
+#if SQLITE_MAX_WORKER_THREADS>0
+/*
+** The main routine for background threads that populate aFile[1] of
+** multi-threaded IncrMerger objects.
+*/
+static void *vdbeIncrPopulateThread(void *pCtx){
+  IncrMerger *pIncr = (IncrMerger*)pCtx;
+  void *pRet = SQLITE_INT_TO_PTR( vdbeIncrPopulate(pIncr) );
+  pIncr->pTask->bDone = 1;
+  return pRet;
+}
+
+/*
+** Launch a background thread to populate aFile[1] of pIncr.
+*/
+static int vdbeIncrBgPopulate(IncrMerger *pIncr){
+  void *p = (void*)pIncr;
+  assert( pIncr->bUseThread );
+  return vdbeSorterCreateThread(pIncr->pTask, vdbeIncrPopulateThread, p);
+}
+#endif
+
+/*
+** This function is called when the PmaReader corresponding to pIncr has
+** finished reading the contents of aFile[0]. Its purpose is to "refill"
+** aFile[0] such that the PmaReader should start rereading it from the
+** beginning.
+**
+** For single-threaded objects, this is accomplished by literally reading 
+** keys from pIncr->pMerger and repopulating aFile[0]. 
+**
+** For multi-threaded objects, all that is required is to wait until the 
+** background thread is finished (if it is not already) and then swap 
+** aFile[0] and aFile[1] in place. If the contents of pMerger have not
+** been exhausted, this function also launches a new background thread
+** to populate the new aFile[1].
+**
+** SQLITE_OK is returned on success, or an SQLite error code otherwise.
+*/
+static int vdbeIncrSwap(IncrMerger *pIncr){
+  int rc = SQLITE_OK;
+
+#if SQLITE_MAX_WORKER_THREADS>0
+  if( pIncr->bUseThread ){
+    rc = vdbeSorterJoinThread(pIncr->pTask);
+
+    if( rc==SQLITE_OK ){
+      SorterFile f0 = pIncr->aFile[0];
+      pIncr->aFile[0] = pIncr->aFile[1];
+      pIncr->aFile[1] = f0;
+    }
+
+    if( rc==SQLITE_OK ){
+      if( pIncr->aFile[0].iEof==pIncr->iStartOff ){
+        pIncr->bEof = 1;
+      }else{
+        rc = vdbeIncrBgPopulate(pIncr);
+      }
+    }
+  }else
+#endif
+  {
+    rc = vdbeIncrPopulate(pIncr);
+    pIncr->aFile[0] = pIncr->aFile[1];
+    if( pIncr->aFile[0].iEof==pIncr->iStartOff ){
+      pIncr->bEof = 1;
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Allocate and return a new IncrMerger object to read data from pMerger.
+**
+** If an OOM condition is encountered, return NULL. In this case free the
+** pMerger argument before returning.
+*/
+static int vdbeIncrMergerNew(
+  SortSubtask *pTask,     /* The thread that will be using the new IncrMerger */
+  MergeEngine *pMerger,   /* The MergeEngine that the IncrMerger will control */
+  IncrMerger **ppOut      /* Write the new IncrMerger here */
+){
+  int rc = SQLITE_OK;
+  IncrMerger *pIncr = *ppOut = (IncrMerger*)
+       (sqlite3FaultSim(100) ? 0 : sqlite3MallocZero(sizeof(*pIncr)));
+  if( pIncr ){
+    pIncr->pMerger = pMerger;
+    pIncr->pTask = pTask;
+    pIncr->mxSz = MAX(pTask->pSorter->mxKeysize+9,pTask->pSorter->mxPmaSize/2);
+    pTask->file2.iEof += pIncr->mxSz;
+  }else{
+    vdbeMergeEngineFree(pMerger);
+    rc = SQLITE_NOMEM_BKPT;
+  }
+  return rc;
+}
+
+#if SQLITE_MAX_WORKER_THREADS>0
+/*
+** Set the "use-threads" flag on object pIncr.
+*/
+static void vdbeIncrMergerSetThreads(IncrMerger *pIncr){
+  pIncr->bUseThread = 1;
+  pIncr->pTask->file2.iEof -= pIncr->mxSz;
+}
+#endif /* SQLITE_MAX_WORKER_THREADS>0 */
+
+
+
+/*
+** Recompute pMerger->aTree[iOut] by comparing the next keys on the
+** two PmaReaders that feed that entry.  Neither of the PmaReaders
+** are advanced.  This routine merely does the comparison.
+*/
+static void vdbeMergeEngineCompare(
+  MergeEngine *pMerger,  /* Merge engine containing PmaReaders to compare */
+  int iOut               /* Store the result in pMerger->aTree[iOut] */
+){
+  int i1;
+  int i2;
+  int iRes;
+  PmaReader *p1;
+  PmaReader *p2;
+
+  assert( iOut<pMerger->nTree && iOut>0 );
+
+  if( iOut>=(pMerger->nTree/2) ){
+    i1 = (iOut - pMerger->nTree/2) * 2;
+    i2 = i1 + 1;
+  }else{
+    i1 = pMerger->aTree[iOut*2];
+    i2 = pMerger->aTree[iOut*2+1];
+  }
+
+  p1 = &pMerger->aReadr[i1];
+  p2 = &pMerger->aReadr[i2];
+
+  if( p1->pFd==0 ){
+    iRes = i2;
+  }else if( p2->pFd==0 ){
+    iRes = i1;
+  }else{
+    SortSubtask *pTask = pMerger->pTask;
+    int bCached = 0;
+    int res;
+    assert( pTask->pUnpacked!=0 );  /* from vdbeSortSubtaskMain() */
+    res = pTask->xCompare(
+        pTask, &bCached, p1->aKey, p1->nKey, p2->aKey, p2->nKey
+    );
+    if( res<=0 ){
+      iRes = i1;
+    }else{
+      iRes = i2;
+    }
+  }
+
+  pMerger->aTree[iOut] = iRes;
+}
+
+/*
+** Allowed values for the eMode parameter to vdbeMergeEngineInit()
+** and vdbePmaReaderIncrMergeInit().
+**
+** Only INCRINIT_NORMAL is valid in single-threaded builds (when
+** SQLITE_MAX_WORKER_THREADS==0).  The other values are only used
+** when there exists one or more separate worker threads.
+*/
+#define INCRINIT_NORMAL 0
+#define INCRINIT_TASK   1
+#define INCRINIT_ROOT   2
+
+/* 
+** Forward reference required as the vdbeIncrMergeInit() and
+** vdbePmaReaderIncrInit() routines are called mutually recursively when
+** building a merge tree.
+*/
+static int vdbePmaReaderIncrInit(PmaReader *pReadr, int eMode);
+
+/*
+** Initialize the MergeEngine object passed as the second argument. Once this
+** function returns, the first key of merged data may be read from the 
+** MergeEngine object in the usual fashion.
+**
+** If argument eMode is INCRINIT_ROOT, then it is assumed that any IncrMerge
+** objects attached to the PmaReader objects that the merger reads from have
+** already been populated, but that they have not yet populated aFile[0] and
+** set the PmaReader objects up to read from it. In this case all that is
+** required is to call vdbePmaReaderNext() on each PmaReader to point it at
+** its first key.
+**
+** Otherwise, if eMode is any value other than INCRINIT_ROOT, then use 
+** vdbePmaReaderIncrMergeInit() to initialize each PmaReader that feeds data 
+** to pMerger.
+**
+** SQLITE_OK is returned if successful, or an SQLite error code otherwise.
+*/
+static int vdbeMergeEngineInit(
+  SortSubtask *pTask,             /* Thread that will run pMerger */
+  MergeEngine *pMerger,           /* MergeEngine to initialize */
+  int eMode                       /* One of the INCRINIT_XXX constants */
+){
+  int rc = SQLITE_OK;             /* Return code */
+  int i;                          /* For looping over PmaReader objects */
+  int nTree = pMerger->nTree;
+
+  /* eMode is always INCRINIT_NORMAL in single-threaded mode */
+  assert( SQLITE_MAX_WORKER_THREADS>0 || eMode==INCRINIT_NORMAL );
+
+  /* Verify that the MergeEngine is assigned to a single thread */
+  assert( pMerger->pTask==0 );
+  pMerger->pTask = pTask;
+
+  for(i=0; i<nTree; i++){
+    if( SQLITE_MAX_WORKER_THREADS>0 && eMode==INCRINIT_ROOT ){
+      /* PmaReaders should be normally initialized in order, as if they are
+      ** reading from the same temp file this makes for more linear file IO.
+      ** However, in the INCRINIT_ROOT case, if PmaReader aReadr[nTask-1] is
+      ** in use it will block the vdbePmaReaderNext() call while it uses
+      ** the main thread to fill its buffer. So calling PmaReaderNext()
+      ** on this PmaReader before any of the multi-threaded PmaReaders takes
+      ** better advantage of multi-processor hardware. */
+      rc = vdbePmaReaderNext(&pMerger->aReadr[nTree-i-1]);
+    }else{
+      rc = vdbePmaReaderIncrInit(&pMerger->aReadr[i], INCRINIT_NORMAL);
+    }
+    if( rc!=SQLITE_OK ) return rc;
+  }
+
+  for(i=pMerger->nTree-1; i>0; i--){
+    vdbeMergeEngineCompare(pMerger, i);
+  }
+  return pTask->pUnpacked->errCode;
+}
+
+/*
+** The PmaReader passed as the first argument is guaranteed to be an
+** incremental-reader (pReadr->pIncr!=0). This function serves to open
+** and/or initialize the temp file related fields of the IncrMerge
+** object at (pReadr->pIncr).
+**
+** If argument eMode is set to INCRINIT_NORMAL, then all PmaReaders
+** in the sub-tree headed by pReadr are also initialized. Data is then 
+** loaded into the buffers belonging to pReadr and it is set to point to 
+** the first key in its range.
+**
+** If argument eMode is set to INCRINIT_TASK, then pReadr is guaranteed
+** to be a multi-threaded PmaReader and this function is being called in a
+** background thread. In this case all PmaReaders in the sub-tree are 
+** initialized as for INCRINIT_NORMAL and the aFile[1] buffer belonging to
+** pReadr is populated. However, pReadr itself is not set up to point
+** to its first key. A call to vdbePmaReaderNext() is still required to do
+** that. 
+**
+** The reason this function does not call vdbePmaReaderNext() immediately 
+** in the INCRINIT_TASK case is that vdbePmaReaderNext() assumes that it has
+** to block on thread (pTask->thread) before accessing aFile[1]. But, since
+** this entire function is being run by thread (pTask->thread), that will
+** lead to the current background thread attempting to join itself.
+**
+** Finally, if argument eMode is set to INCRINIT_ROOT, it may be assumed
+** that pReadr->pIncr is a multi-threaded IncrMerge objects, and that all
+** child-trees have already been initialized using IncrInit(INCRINIT_TASK).
+** In this case vdbePmaReaderNext() is called on all child PmaReaders and
+** the current PmaReader set to point to the first key in its range.
+**
+** SQLITE_OK is returned if successful, or an SQLite error code otherwise.
+*/
+static int vdbePmaReaderIncrMergeInit(PmaReader *pReadr, int eMode){
+  int rc = SQLITE_OK;
+  IncrMerger *pIncr = pReadr->pIncr;
+  SortSubtask *pTask = pIncr->pTask;
+  sqlite3 *db = pTask->pSorter->db;
+
+  /* eMode is always INCRINIT_NORMAL in single-threaded mode */
+  assert( SQLITE_MAX_WORKER_THREADS>0 || eMode==INCRINIT_NORMAL );
+
+  rc = vdbeMergeEngineInit(pTask, pIncr->pMerger, eMode);
+
+  /* Set up the required files for pIncr. A multi-theaded IncrMerge object
+  ** requires two temp files to itself, whereas a single-threaded object
+  ** only requires a region of pTask->file2. */
+  if( rc==SQLITE_OK ){
+    int mxSz = pIncr->mxSz;
+#if SQLITE_MAX_WORKER_THREADS>0
+    if( pIncr->bUseThread ){
+      rc = vdbeSorterOpenTempFile(db, mxSz, &pIncr->aFile[0].pFd);
+      if( rc==SQLITE_OK ){
+        rc = vdbeSorterOpenTempFile(db, mxSz, &pIncr->aFile[1].pFd);
+      }
+    }else
+#endif
+    /*if( !pIncr->bUseThread )*/{
+      if( pTask->file2.pFd==0 ){
+        assert( pTask->file2.iEof>0 );
+        rc = vdbeSorterOpenTempFile(db, pTask->file2.iEof, &pTask->file2.pFd);
+        pTask->file2.iEof = 0;
+      }
+      if( rc==SQLITE_OK ){
+        pIncr->aFile[1].pFd = pTask->file2.pFd;
+        pIncr->iStartOff = pTask->file2.iEof;
+        pTask->file2.iEof += mxSz;
+      }
+    }
+  }
+
+#if SQLITE_MAX_WORKER_THREADS>0
+  if( rc==SQLITE_OK && pIncr->bUseThread ){
+    /* Use the current thread to populate aFile[1], even though this
+    ** PmaReader is multi-threaded. If this is an INCRINIT_TASK object,
+    ** then this function is already running in background thread 
+    ** pIncr->pTask->thread. 
+    **
+    ** If this is the INCRINIT_ROOT object, then it is running in the 
+    ** main VDBE thread. But that is Ok, as that thread cannot return
+    ** control to the VDBE or proceed with anything useful until the 
+    ** first results are ready from this merger object anyway.
+    */
+    assert( eMode==INCRINIT_ROOT || eMode==INCRINIT_TASK );
+    rc = vdbeIncrPopulate(pIncr);
+  }
+#endif
+
+  if( rc==SQLITE_OK && (SQLITE_MAX_WORKER_THREADS==0 || eMode!=INCRINIT_TASK) ){
+    rc = vdbePmaReaderNext(pReadr);
+  }
+
+  return rc;
+}
+
+#if SQLITE_MAX_WORKER_THREADS>0
+/*
+** The main routine for vdbePmaReaderIncrMergeInit() operations run in 
+** background threads.
+*/
+static void *vdbePmaReaderBgIncrInit(void *pCtx){
+  PmaReader *pReader = (PmaReader*)pCtx;
+  void *pRet = SQLITE_INT_TO_PTR(
+                  vdbePmaReaderIncrMergeInit(pReader,INCRINIT_TASK)
+               );
+  pReader->pIncr->pTask->bDone = 1;
+  return pRet;
+}
+#endif
+
+/*
+** If the PmaReader passed as the first argument is not an incremental-reader
+** (if pReadr->pIncr==0), then this function is a no-op. Otherwise, it invokes
+** the vdbePmaReaderIncrMergeInit() function with the parameters passed to
+** this routine to initialize the incremental merge.
+** 
+** If the IncrMerger object is multi-threaded (IncrMerger.bUseThread==1), 
+** then a background thread is launched to call vdbePmaReaderIncrMergeInit().
+** Or, if the IncrMerger is single threaded, the same function is called
+** using the current thread.
+*/
+static int vdbePmaReaderIncrInit(PmaReader *pReadr, int eMode){
+  IncrMerger *pIncr = pReadr->pIncr;   /* Incremental merger */
+  int rc = SQLITE_OK;                  /* Return code */
+  if( pIncr ){
+#if SQLITE_MAX_WORKER_THREADS>0
+    assert( pIncr->bUseThread==0 || eMode==INCRINIT_TASK );
+    if( pIncr->bUseThread ){
+      void *pCtx = (void*)pReadr;
+      rc = vdbeSorterCreateThread(pIncr->pTask, vdbePmaReaderBgIncrInit, pCtx);
+    }else
+#endif
+    {
+      rc = vdbePmaReaderIncrMergeInit(pReadr, eMode);
+    }
+  }
+  return rc;
+}
+
+/*
+** Allocate a new MergeEngine object to merge the contents of nPMA level-0
+** PMAs from pTask->file. If no error occurs, set *ppOut to point to
+** the new object and return SQLITE_OK. Or, if an error does occur, set *ppOut
+** to NULL and return an SQLite error code.
+**
+** When this function is called, *piOffset is set to the offset of the
+** first PMA to read from pTask->file. Assuming no error occurs, it is 
+** set to the offset immediately following the last byte of the last
+** PMA before returning. If an error does occur, then the final value of
+** *piOffset is undefined.
+*/
+static int vdbeMergeEngineLevel0(
+  SortSubtask *pTask,             /* Sorter task to read from */
+  int nPMA,                       /* Number of PMAs to read */
+  i64 *piOffset,                  /* IN/OUT: Readr offset in pTask->file */
+  MergeEngine **ppOut             /* OUT: New merge-engine */
+){
+  MergeEngine *pNew;              /* Merge engine to return */
+  i64 iOff = *piOffset;
+  int i;
+  int rc = SQLITE_OK;
+
+  *ppOut = pNew = vdbeMergeEngineNew(nPMA);
+  if( pNew==0 ) rc = SQLITE_NOMEM_BKPT;
+
+  for(i=0; i<nPMA && rc==SQLITE_OK; i++){
+    i64 nDummy = 0;
+    PmaReader *pReadr = &pNew->aReadr[i];
+    rc = vdbePmaReaderInit(pTask, &pTask->file, iOff, pReadr, &nDummy);
+    iOff = pReadr->iEof;
+  }
+
+  if( rc!=SQLITE_OK ){
+    vdbeMergeEngineFree(pNew);
+    *ppOut = 0;
+  }
+  *piOffset = iOff;
+  return rc;
+}
+
+/*
+** Return the depth of a tree comprising nPMA PMAs, assuming a fanout of
+** SORTER_MAX_MERGE_COUNT. The returned value does not include leaf nodes.
+**
+** i.e.
+**
+**   nPMA<=16    -> TreeDepth() == 0
+**   nPMA<=256   -> TreeDepth() == 1
+**   nPMA<=65536 -> TreeDepth() == 2
+*/
+static int vdbeSorterTreeDepth(int nPMA){
+  int nDepth = 0;
+  i64 nDiv = SORTER_MAX_MERGE_COUNT;
+  while( nDiv < (i64)nPMA ){
+    nDiv = nDiv * SORTER_MAX_MERGE_COUNT;
+    nDepth++;
+  }
+  return nDepth;
+}
+
+/*
+** pRoot is the root of an incremental merge-tree with depth nDepth (according
+** to vdbeSorterTreeDepth()). pLeaf is the iSeq'th leaf to be added to the
+** tree, counting from zero. This function adds pLeaf to the tree.
+**
+** If successful, SQLITE_OK is returned. If an error occurs, an SQLite error
+** code is returned and pLeaf is freed.
+*/
+static int vdbeSorterAddToTree(
+  SortSubtask *pTask,             /* Task context */
+  int nDepth,                     /* Depth of tree according to TreeDepth() */
+  int iSeq,                       /* Sequence number of leaf within tree */
+  MergeEngine *pRoot,             /* Root of tree */
+  MergeEngine *pLeaf              /* Leaf to add to tree */
+){
+  int rc = SQLITE_OK;
+  int nDiv = 1;
+  int i;
+  MergeEngine *p = pRoot;
+  IncrMerger *pIncr;
+
+  rc = vdbeIncrMergerNew(pTask, pLeaf, &pIncr);
+
+  for(i=1; i<nDepth; i++){
+    nDiv = nDiv * SORTER_MAX_MERGE_COUNT;
+  }
+
+  for(i=1; i<nDepth && rc==SQLITE_OK; i++){
+    int iIter = (iSeq / nDiv) % SORTER_MAX_MERGE_COUNT;
+    PmaReader *pReadr = &p->aReadr[iIter];
+
+    if( pReadr->pIncr==0 ){
+      MergeEngine *pNew = vdbeMergeEngineNew(SORTER_MAX_MERGE_COUNT);
+      if( pNew==0 ){
+        rc = SQLITE_NOMEM_BKPT;
+      }else{
+        rc = vdbeIncrMergerNew(pTask, pNew, &pReadr->pIncr);
+      }
+    }
+    if( rc==SQLITE_OK ){
+      p = pReadr->pIncr->pMerger;
+      nDiv = nDiv / SORTER_MAX_MERGE_COUNT;
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    p->aReadr[iSeq % SORTER_MAX_MERGE_COUNT].pIncr = pIncr;
+  }else{
+    vdbeIncrFree(pIncr);
+  }
+  return rc;
+}
+
+/*
+** This function is called as part of a SorterRewind() operation on a sorter
+** that has already written two or more level-0 PMAs to one or more temp
+** files. It builds a tree of MergeEngine/IncrMerger/PmaReader objects that 
+** can be used to incrementally merge all PMAs on disk.
+**
+** If successful, SQLITE_OK is returned and *ppOut set to point to the
+** MergeEngine object at the root of the tree before returning. Or, if an
+** error occurs, an SQLite error code is returned and the final value 
+** of *ppOut is undefined.
+*/
+static int vdbeSorterMergeTreeBuild(
+  VdbeSorter *pSorter,       /* The VDBE cursor that implements the sort */
+  MergeEngine **ppOut        /* Write the MergeEngine here */
+){
+  MergeEngine *pMain = 0;
+  int rc = SQLITE_OK;
+  int iTask;
+
+#if SQLITE_MAX_WORKER_THREADS>0
+  /* If the sorter uses more than one task, then create the top-level 
+  ** MergeEngine here. This MergeEngine will read data from exactly 
+  ** one PmaReader per sub-task.  */
+  assert( pSorter->bUseThreads || pSorter->nTask==1 );
+  if( pSorter->nTask>1 ){
+    pMain = vdbeMergeEngineNew(pSorter->nTask);
+    if( pMain==0 ) rc = SQLITE_NOMEM_BKPT;
+  }
+#endif
+
+  for(iTask=0; rc==SQLITE_OK && iTask<pSorter->nTask; iTask++){
+    SortSubtask *pTask = &pSorter->aTask[iTask];
+    assert( pTask->nPMA>0 || SQLITE_MAX_WORKER_THREADS>0 );
+    if( SQLITE_MAX_WORKER_THREADS==0 || pTask->nPMA ){
+      MergeEngine *pRoot = 0;     /* Root node of tree for this task */
+      int nDepth = vdbeSorterTreeDepth(pTask->nPMA);
+      i64 iReadOff = 0;
+
+      if( pTask->nPMA<=SORTER_MAX_MERGE_COUNT ){
+        rc = vdbeMergeEngineLevel0(pTask, pTask->nPMA, &iReadOff, &pRoot);
+      }else{
+        int i;
+        int iSeq = 0;
+        pRoot = vdbeMergeEngineNew(SORTER_MAX_MERGE_COUNT);
+        if( pRoot==0 ) rc = SQLITE_NOMEM_BKPT;
+        for(i=0; i<pTask->nPMA && rc==SQLITE_OK; i += SORTER_MAX_MERGE_COUNT){
+          MergeEngine *pMerger = 0; /* New level-0 PMA merger */
+          int nReader;              /* Number of level-0 PMAs to merge */
+
+          nReader = MIN(pTask->nPMA - i, SORTER_MAX_MERGE_COUNT);
+          rc = vdbeMergeEngineLevel0(pTask, nReader, &iReadOff, &pMerger);
+          if( rc==SQLITE_OK ){
+            rc = vdbeSorterAddToTree(pTask, nDepth, iSeq++, pRoot, pMerger);
+          }
+        }
+      }
+
+      if( rc==SQLITE_OK ){
+#if SQLITE_MAX_WORKER_THREADS>0
+        if( pMain!=0 ){
+          rc = vdbeIncrMergerNew(pTask, pRoot, &pMain->aReadr[iTask].pIncr);
+        }else
+#endif
+        {
+          assert( pMain==0 );
+          pMain = pRoot;
+        }
+      }else{
+        vdbeMergeEngineFree(pRoot);
+      }
+    }
+  }
+
+  if( rc!=SQLITE_OK ){
+    vdbeMergeEngineFree(pMain);
+    pMain = 0;
+  }
+  *ppOut = pMain;
+  return rc;
+}
+
+/*
+** This function is called as part of an sqlite3VdbeSorterRewind() operation
+** on a sorter that has written two or more PMAs to temporary files. It sets
+** up either VdbeSorter.pMerger (for single threaded sorters) or pReader
+** (for multi-threaded sorters) so that it can be used to iterate through
+** all records stored in the sorter.
+**
+** SQLITE_OK is returned if successful, or an SQLite error code otherwise.
+*/
+static int vdbeSorterSetupMerge(VdbeSorter *pSorter){
+  int rc;                         /* Return code */
+  SortSubtask *pTask0 = &pSorter->aTask[0];
+  MergeEngine *pMain = 0;
+#if SQLITE_MAX_WORKER_THREADS
+  sqlite3 *db = pTask0->pSorter->db;
+  int i;
+  SorterCompare xCompare = vdbeSorterGetCompare(pSorter);
+  for(i=0; i<pSorter->nTask; i++){
+    pSorter->aTask[i].xCompare = xCompare;
+  }
+#endif
+
+  rc = vdbeSorterMergeTreeBuild(pSorter, &pMain);
+  if( rc==SQLITE_OK ){
+#if SQLITE_MAX_WORKER_THREADS
+    assert( pSorter->bUseThreads==0 || pSorter->nTask>1 );
+    if( pSorter->bUseThreads ){
+      int iTask;
+      PmaReader *pReadr = 0;
+      SortSubtask *pLast = &pSorter->aTask[pSorter->nTask-1];
+      rc = vdbeSortAllocUnpacked(pLast);
+      if( rc==SQLITE_OK ){
+        pReadr = (PmaReader*)sqlite3DbMallocZero(db, sizeof(PmaReader));
+        pSorter->pReader = pReadr;
+        if( pReadr==0 ) rc = SQLITE_NOMEM_BKPT;
+      }
+      if( rc==SQLITE_OK ){
+        rc = vdbeIncrMergerNew(pLast, pMain, &pReadr->pIncr);
+        if( rc==SQLITE_OK ){
+          vdbeIncrMergerSetThreads(pReadr->pIncr);
+          for(iTask=0; iTask<(pSorter->nTask-1); iTask++){
+            IncrMerger *pIncr;
+            if( (pIncr = pMain->aReadr[iTask].pIncr) ){
+              vdbeIncrMergerSetThreads(pIncr);
+              assert( pIncr->pTask!=pLast );
+            }
+          }
+          for(iTask=0; rc==SQLITE_OK && iTask<pSorter->nTask; iTask++){
+            /* Check that:
+            **   
+            **   a) The incremental merge object is configured to use the
+            **      right task, and
+            **   b) If it is using task (nTask-1), it is configured to run
+            **      in single-threaded mode. This is important, as the
+            **      root merge (INCRINIT_ROOT) will be using the same task
+            **      object.
+            */
+            PmaReader *p = &pMain->aReadr[iTask];
+            assert( p->pIncr==0 || (
+                (p->pIncr->pTask==&pSorter->aTask[iTask])             /* a */
+             && (iTask!=pSorter->nTask-1 || p->pIncr->bUseThread==0)  /* b */
+            ));
+            rc = vdbePmaReaderIncrInit(p, INCRINIT_TASK);
+          }
+        }
+        pMain = 0;
+      }
+      if( rc==SQLITE_OK ){
+        rc = vdbePmaReaderIncrMergeInit(pReadr, INCRINIT_ROOT);
+      }
+    }else
+#endif
+    {
+      rc = vdbeMergeEngineInit(pTask0, pMain, INCRINIT_NORMAL);
+      pSorter->pMerger = pMain;
+      pMain = 0;
+    }
+  }
+
+  if( rc!=SQLITE_OK ){
+    vdbeMergeEngineFree(pMain);
+  }
+  return rc;
+}
+
+
+/*
+** Once the sorter has been populated by calls to sqlite3VdbeSorterWrite,
+** this function is called to prepare for iterating through the records
+** in sorted order.
+*/
+SQLITE_PRIVATE int sqlite3VdbeSorterRewind(const VdbeCursor *pCsr, int *pbEof){
+  VdbeSorter *pSorter;
+  int rc = SQLITE_OK;             /* Return code */
+
+  assert( pCsr->eCurType==CURTYPE_SORTER );
+  pSorter = pCsr->uc.pSorter;
+  assert( pSorter );
+
+  /* If no data has been written to disk, then do not do so now. Instead,
+  ** sort the VdbeSorter.pRecord list. The vdbe layer will read data directly
+  ** from the in-memory list.  */
+  if( pSorter->bUsePMA==0 ){
+    if( pSorter->list.pList ){
+      *pbEof = 0;
+      rc = vdbeSorterSort(&pSorter->aTask[0], &pSorter->list);
+    }else{
+      *pbEof = 1;
+    }
+    return rc;
+  }
+
+  /* Write the current in-memory list to a PMA. When the VdbeSorterWrite() 
+  ** function flushes the contents of memory to disk, it immediately always
+  ** creates a new list consisting of a single key immediately afterwards.
+  ** So the list is never empty at this point.  */
+  assert( pSorter->list.pList );
+  rc = vdbeSorterFlushPMA(pSorter);
+
+  /* Join all threads */
+  rc = vdbeSorterJoinAll(pSorter, rc);
+
+  vdbeSorterRewindDebug("rewind");
+
+  /* Assuming no errors have occurred, set up a merger structure to 
+  ** incrementally read and merge all remaining PMAs.  */
+  assert( pSorter->pReader==0 );
+  if( rc==SQLITE_OK ){
+    rc = vdbeSorterSetupMerge(pSorter);
+    *pbEof = 0;
+  }
+
+  vdbeSorterRewindDebug("rewinddone");
+  return rc;
+}
+
+/*
+** Advance to the next element in the sorter.
+*/
+SQLITE_PRIVATE int sqlite3VdbeSorterNext(sqlite3 *db, const VdbeCursor *pCsr, int *pbEof){
+  VdbeSorter *pSorter;
+  int rc;                         /* Return code */
+
+  assert( pCsr->eCurType==CURTYPE_SORTER );
+  pSorter = pCsr->uc.pSorter;
+  assert( pSorter->bUsePMA || (pSorter->pReader==0 && pSorter->pMerger==0) );
+  if( pSorter->bUsePMA ){
+    assert( pSorter->pReader==0 || pSorter->pMerger==0 );
+    assert( pSorter->bUseThreads==0 || pSorter->pReader );
+    assert( pSorter->bUseThreads==1 || pSorter->pMerger );
+#if SQLITE_MAX_WORKER_THREADS>0
+    if( pSorter->bUseThreads ){
+      rc = vdbePmaReaderNext(pSorter->pReader);
+      *pbEof = (pSorter->pReader->pFd==0);
+    }else
+#endif
+    /*if( !pSorter->bUseThreads )*/ {
+      assert( pSorter->pMerger!=0 );
+      assert( pSorter->pMerger->pTask==(&pSorter->aTask[0]) );
+      rc = vdbeMergeEngineStep(pSorter->pMerger, pbEof);
+    }
+  }else{
+    SorterRecord *pFree = pSorter->list.pList;
+    pSorter->list.pList = pFree->u.pNext;
+    pFree->u.pNext = 0;
+    if( pSorter->list.aMemory==0 ) vdbeSorterRecordFree(db, pFree);
+    *pbEof = !pSorter->list.pList;
+    rc = SQLITE_OK;
+  }
+  return rc;
+}
+
+/*
+** Return a pointer to a buffer owned by the sorter that contains the 
+** current key.
+*/
+static void *vdbeSorterRowkey(
+  const VdbeSorter *pSorter,      /* Sorter object */
+  int *pnKey                      /* OUT: Size of current key in bytes */
+){
+  void *pKey;
+  if( pSorter->bUsePMA ){
+    PmaReader *pReader;
+#if SQLITE_MAX_WORKER_THREADS>0
+    if( pSorter->bUseThreads ){
+      pReader = pSorter->pReader;
+    }else
+#endif
+    /*if( !pSorter->bUseThreads )*/{
+      pReader = &pSorter->pMerger->aReadr[pSorter->pMerger->aTree[1]];
+    }
+    *pnKey = pReader->nKey;
+    pKey = pReader->aKey;
+  }else{
+    *pnKey = pSorter->list.pList->nVal;
+    pKey = SRVAL(pSorter->list.pList);
+  }
+  return pKey;
+}
+
+/*
+** Copy the current sorter key into the memory cell pOut.
+*/
+SQLITE_PRIVATE int sqlite3VdbeSorterRowkey(const VdbeCursor *pCsr, Mem *pOut){
+  VdbeSorter *pSorter;
+  void *pKey; int nKey;           /* Sorter key to copy into pOut */
+
+  assert( pCsr->eCurType==CURTYPE_SORTER );
+  pSorter = pCsr->uc.pSorter;
+  pKey = vdbeSorterRowkey(pSorter, &nKey);
+  if( sqlite3VdbeMemClearAndResize(pOut, nKey) ){
+    return SQLITE_NOMEM_BKPT;
+  }
+  pOut->n = nKey;
+  MemSetTypeFlag(pOut, MEM_Blob);
+  memcpy(pOut->z, pKey, nKey);
+
+  return SQLITE_OK;
+}
+
+/*
+** Compare the key in memory cell pVal with the key that the sorter cursor
+** passed as the first argument currently points to. For the purposes of
+** the comparison, ignore the rowid field at the end of each record.
+**
+** If the sorter cursor key contains any NULL values, consider it to be
+** less than pVal. Even if pVal also contains NULL values.
+**
+** If an error occurs, return an SQLite error code (i.e. SQLITE_NOMEM).
+** Otherwise, set *pRes to a negative, zero or positive value if the
+** key in pVal is smaller than, equal to or larger than the current sorter
+** key.
+**
+** This routine forms the core of the OP_SorterCompare opcode, which in
+** turn is used to verify uniqueness when constructing a UNIQUE INDEX.
+*/
+SQLITE_PRIVATE int sqlite3VdbeSorterCompare(
+  const VdbeCursor *pCsr,         /* Sorter cursor */
+  Mem *pVal,                      /* Value to compare to current sorter key */
+  int nKeyCol,                    /* Compare this many columns */
+  int *pRes                       /* OUT: Result of comparison */
+){
+  VdbeSorter *pSorter;
+  UnpackedRecord *r2;
+  KeyInfo *pKeyInfo;
+  int i;
+  void *pKey; int nKey;           /* Sorter key to compare pVal with */
+
+  assert( pCsr->eCurType==CURTYPE_SORTER );
+  pSorter = pCsr->uc.pSorter;
+  r2 = pSorter->pUnpacked;
+  pKeyInfo = pCsr->pKeyInfo;
+  if( r2==0 ){
+    char *p;
+    r2 = pSorter->pUnpacked = sqlite3VdbeAllocUnpackedRecord(pKeyInfo,0,0,&p);
+    assert( pSorter->pUnpacked==(UnpackedRecord*)p );
+    if( r2==0 ) return SQLITE_NOMEM_BKPT;
+    r2->nField = nKeyCol;
+  }
+  assert( r2->nField==nKeyCol );
+
+  pKey = vdbeSorterRowkey(pSorter, &nKey);
+  sqlite3VdbeRecordUnpack(pKeyInfo, nKey, pKey, r2);
+  for(i=0; i<nKeyCol; i++){
+    if( r2->aMem[i].flags & MEM_Null ){
+      *pRes = -1;
+      return SQLITE_OK;
+    }
+  }
+
+  *pRes = sqlite3VdbeRecordCompare(pVal->n, pVal->z, r2);
+  return SQLITE_OK;
+}
+
+/************** End of vdbesort.c ********************************************/
+/************** Begin file memjournal.c **************************************/
+/*
+** 2008 October 7
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains code use to implement an in-memory rollback journal.
+** The in-memory rollback journal is used to journal transactions for
+** ":memory:" databases and when the journal_mode=MEMORY pragma is used.
+**
+** Update:  The in-memory journal is also used to temporarily cache
+** smaller journals that are not critical for power-loss recovery.
+** For example, statement journals that are not too big will be held
+** entirely in memory, thus reducing the number of file I/O calls, and
+** more importantly, reducing temporary file creation events.  If these
+** journals become too large for memory, they are spilled to disk.  But
+** in the common case, they are usually small and no file I/O needs to
+** occur.
+*/
+/* #include "sqliteInt.h" */
+
+/* Forward references to internal structures */
+typedef struct MemJournal MemJournal;
+typedef struct FilePoint FilePoint;
+typedef struct FileChunk FileChunk;
+
+/*
+** The rollback journal is composed of a linked list of these structures.
+**
+** The zChunk array is always at least 8 bytes in size - usually much more.
+** Its actual size is stored in the MemJournal.nChunkSize variable.
+*/
+struct FileChunk {
+  FileChunk *pNext;               /* Next chunk in the journal */
+  u8 zChunk[8];                   /* Content of this chunk */
+};
+
+/*
+** By default, allocate this many bytes of memory for each FileChunk object.
+*/
+#define MEMJOURNAL_DFLT_FILECHUNKSIZE 1024
+
+/*
+** For chunk size nChunkSize, return the number of bytes that should
+** be allocated for each FileChunk structure.
+*/
+#define fileChunkSize(nChunkSize) (sizeof(FileChunk) + ((nChunkSize)-8))
+
+/*
+** An instance of this object serves as a cursor into the rollback journal.
+** The cursor can be either for reading or writing.
+*/
+struct FilePoint {
+  sqlite3_int64 iOffset;          /* Offset from the beginning of the file */
+  FileChunk *pChunk;              /* Specific chunk into which cursor points */
+};
+
+/*
+** This structure is a subclass of sqlite3_file. Each open memory-journal
+** is an instance of this class.
+*/
+struct MemJournal {
+  const sqlite3_io_methods *pMethod; /* Parent class. MUST BE FIRST */
+  int nChunkSize;                 /* In-memory chunk-size */
+
+  int nSpill;                     /* Bytes of data before flushing */
+  int nSize;                      /* Bytes of data currently in memory */
+  FileChunk *pFirst;              /* Head of in-memory chunk-list */
+  FilePoint endpoint;             /* Pointer to the end of the file */
+  FilePoint readpoint;            /* Pointer to the end of the last xRead() */
+
+  int flags;                      /* xOpen flags */
+  sqlite3_vfs *pVfs;              /* The "real" underlying VFS */
+  const char *zJournal;           /* Name of the journal file */
+};
+
+/*
+** Read data from the in-memory journal file.  This is the implementation
+** of the sqlite3_vfs.xRead method.
+*/
+static int memjrnlRead(
+  sqlite3_file *pJfd,    /* The journal file from which to read */
+  void *zBuf,            /* Put the results here */
+  int iAmt,              /* Number of bytes to read */
+  sqlite_int64 iOfst     /* Begin reading at this offset */
+){
+  MemJournal *p = (MemJournal *)pJfd;
+  u8 *zOut = zBuf;
+  int nRead = iAmt;
+  int iChunkOffset;
+  FileChunk *pChunk;
+
+#ifdef SQLITE_ENABLE_ATOMIC_WRITE
+  if( (iAmt+iOfst)>p->endpoint.iOffset ){
+    return SQLITE_IOERR_SHORT_READ;
+  }
+#endif
+
+  assert( (iAmt+iOfst)<=p->endpoint.iOffset );
+  assert( p->readpoint.iOffset==0 || p->readpoint.pChunk!=0 );
+  if( p->readpoint.iOffset!=iOfst || iOfst==0 ){
+    sqlite3_int64 iOff = 0;
+    for(pChunk=p->pFirst; 
+        ALWAYS(pChunk) && (iOff+p->nChunkSize)<=iOfst;
+        pChunk=pChunk->pNext
+    ){
+      iOff += p->nChunkSize;
+    }
+  }else{
+    pChunk = p->readpoint.pChunk;
+    assert( pChunk!=0 );
+  }
+
+  iChunkOffset = (int)(iOfst%p->nChunkSize);
+  do {
+    int iSpace = p->nChunkSize - iChunkOffset;
+    int nCopy = MIN(nRead, (p->nChunkSize - iChunkOffset));
+    memcpy(zOut, (u8*)pChunk->zChunk + iChunkOffset, nCopy);
+    zOut += nCopy;
+    nRead -= iSpace;
+    iChunkOffset = 0;
+  } while( nRead>=0 && (pChunk=pChunk->pNext)!=0 && nRead>0 );
+  p->readpoint.iOffset = pChunk ? iOfst+iAmt : 0;
+  p->readpoint.pChunk = pChunk;
+
+  return SQLITE_OK;
+}
+
+/*
+** Free the list of FileChunk structures headed at MemJournal.pFirst.
+*/
+static void memjrnlFreeChunks(MemJournal *p){
+  FileChunk *pIter;
+  FileChunk *pNext;
+  for(pIter=p->pFirst; pIter; pIter=pNext){
+    pNext = pIter->pNext;
+    sqlite3_free(pIter);
+  } 
+  p->pFirst = 0;
+}
+
+/*
+** Flush the contents of memory to a real file on disk.
+*/
+static int memjrnlCreateFile(MemJournal *p){
+  int rc;
+  sqlite3_file *pReal = (sqlite3_file*)p;
+  MemJournal copy = *p;
+
+  memset(p, 0, sizeof(MemJournal));
+  rc = sqlite3OsOpen(copy.pVfs, copy.zJournal, pReal, copy.flags, 0);
+  if( rc==SQLITE_OK ){
+    int nChunk = copy.nChunkSize;
+    i64 iOff = 0;
+    FileChunk *pIter;
+    for(pIter=copy.pFirst; pIter; pIter=pIter->pNext){
+      if( iOff + nChunk > copy.endpoint.iOffset ){
+        nChunk = copy.endpoint.iOffset - iOff;
+      }
+      rc = sqlite3OsWrite(pReal, (u8*)pIter->zChunk, nChunk, iOff);
+      if( rc ) break;
+      iOff += nChunk;
+    }
+    if( rc==SQLITE_OK ){
+      /* No error has occurred. Free the in-memory buffers. */
+      memjrnlFreeChunks(&copy);
+    }
+  }
+  if( rc!=SQLITE_OK ){
+    /* If an error occurred while creating or writing to the file, restore
+    ** the original before returning. This way, SQLite uses the in-memory
+    ** journal data to roll back changes made to the internal page-cache
+    ** before this function was called.  */
+    sqlite3OsClose(pReal);
+    *p = copy;
+  }
+  return rc;
+}
+
+
+/*
+** Write data to the file.
+*/
+static int memjrnlWrite(
+  sqlite3_file *pJfd,    /* The journal file into which to write */
+  const void *zBuf,      /* Take data to be written from here */
+  int iAmt,              /* Number of bytes to write */
+  sqlite_int64 iOfst     /* Begin writing at this offset into the file */
+){
+  MemJournal *p = (MemJournal *)pJfd;
+  int nWrite = iAmt;
+  u8 *zWrite = (u8 *)zBuf;
+
+  /* If the file should be created now, create it and write the new data
+  ** into the file on disk. */
+  if( p->nSpill>0 && (iAmt+iOfst)>p->nSpill ){
+    int rc = memjrnlCreateFile(p);
+    if( rc==SQLITE_OK ){
+      rc = sqlite3OsWrite(pJfd, zBuf, iAmt, iOfst);
+    }
+    return rc;
+  }
+
+  /* If the contents of this write should be stored in memory */
+  else{
+    /* An in-memory journal file should only ever be appended to. Random
+    ** access writes are not required. The only exception to this is when
+    ** the in-memory journal is being used by a connection using the
+    ** atomic-write optimization. In this case the first 28 bytes of the
+    ** journal file may be written as part of committing the transaction. */ 
+    assert( iOfst==p->endpoint.iOffset || iOfst==0 );
+#ifdef SQLITE_ENABLE_ATOMIC_WRITE
+    if( iOfst==0 && p->pFirst ){
+      assert( p->nChunkSize>iAmt );
+      memcpy((u8*)p->pFirst->zChunk, zBuf, iAmt);
+    }else
+#else
+    assert( iOfst>0 || p->pFirst==0 );
+#endif
+    {
+      while( nWrite>0 ){
+        FileChunk *pChunk = p->endpoint.pChunk;
+        int iChunkOffset = (int)(p->endpoint.iOffset%p->nChunkSize);
+        int iSpace = MIN(nWrite, p->nChunkSize - iChunkOffset);
+
+        if( iChunkOffset==0 ){
+          /* New chunk is required to extend the file. */
+          FileChunk *pNew = sqlite3_malloc(fileChunkSize(p->nChunkSize));
+          if( !pNew ){
+            return SQLITE_IOERR_NOMEM_BKPT;
+          }
+          pNew->pNext = 0;
+          if( pChunk ){
+            assert( p->pFirst );
+            pChunk->pNext = pNew;
+          }else{
+            assert( !p->pFirst );
+            p->pFirst = pNew;
+          }
+          p->endpoint.pChunk = pNew;
+        }
+
+        memcpy((u8*)p->endpoint.pChunk->zChunk + iChunkOffset, zWrite, iSpace);
+        zWrite += iSpace;
+        nWrite -= iSpace;
+        p->endpoint.iOffset += iSpace;
+      }
+      p->nSize = iAmt + iOfst;
+    }
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Truncate the file.
+**
+** If the journal file is already on disk, truncate it there. Or, if it
+** is still in main memory but is being truncated to zero bytes in size,
+** ignore 
+*/
+static int memjrnlTruncate(sqlite3_file *pJfd, sqlite_int64 size){
+  MemJournal *p = (MemJournal *)pJfd;
+  if( ALWAYS(size==0) ){
+    memjrnlFreeChunks(p);
+    p->nSize = 0;
+    p->endpoint.pChunk = 0;
+    p->endpoint.iOffset = 0;
+    p->readpoint.pChunk = 0;
+    p->readpoint.iOffset = 0;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Close the file.
+*/
+static int memjrnlClose(sqlite3_file *pJfd){
+  MemJournal *p = (MemJournal *)pJfd;
+  memjrnlFreeChunks(p);
+  return SQLITE_OK;
+}
+
+/*
+** Sync the file.
+**
+** If the real file has been created, call its xSync method. Otherwise, 
+** syncing an in-memory journal is a no-op. 
+*/
+static int memjrnlSync(sqlite3_file *pJfd, int flags){
+  UNUSED_PARAMETER2(pJfd, flags);
+  return SQLITE_OK;
+}
+
+/*
+** Query the size of the file in bytes.
+*/
+static int memjrnlFileSize(sqlite3_file *pJfd, sqlite_int64 *pSize){
+  MemJournal *p = (MemJournal *)pJfd;
+  *pSize = (sqlite_int64) p->endpoint.iOffset;
+  return SQLITE_OK;
+}
+
+/*
+** Table of methods for MemJournal sqlite3_file object.
+*/
+static const struct sqlite3_io_methods MemJournalMethods = {
+  1,                /* iVersion */
+  memjrnlClose,     /* xClose */
+  memjrnlRead,      /* xRead */
+  memjrnlWrite,     /* xWrite */
+  memjrnlTruncate,  /* xTruncate */
+  memjrnlSync,      /* xSync */
+  memjrnlFileSize,  /* xFileSize */
+  0,                /* xLock */
+  0,                /* xUnlock */
+  0,                /* xCheckReservedLock */
+  0,                /* xFileControl */
+  0,                /* xSectorSize */
+  0,                /* xDeviceCharacteristics */
+  0,                /* xShmMap */
+  0,                /* xShmLock */
+  0,                /* xShmBarrier */
+  0,                /* xShmUnmap */
+  0,                /* xFetch */
+  0                 /* xUnfetch */
+};
+
+/* 
+** Open a journal file. 
+**
+** The behaviour of the journal file depends on the value of parameter 
+** nSpill. If nSpill is 0, then the journal file is always create and 
+** accessed using the underlying VFS. If nSpill is less than zero, then
+** all content is always stored in main-memory. Finally, if nSpill is a
+** positive value, then the journal file is initially created in-memory
+** but may be flushed to disk later on. In this case the journal file is
+** flushed to disk either when it grows larger than nSpill bytes in size,
+** or when sqlite3JournalCreate() is called.
+*/
+SQLITE_PRIVATE int sqlite3JournalOpen(
+  sqlite3_vfs *pVfs,         /* The VFS to use for actual file I/O */
+  const char *zName,         /* Name of the journal file */
+  sqlite3_file *pJfd,        /* Preallocated, blank file handle */
+  int flags,                 /* Opening flags */
+  int nSpill                 /* Bytes buffered before opening the file */
+){
+  MemJournal *p = (MemJournal*)pJfd;
+
+  /* Zero the file-handle object. If nSpill was passed zero, initialize
+  ** it using the sqlite3OsOpen() function of the underlying VFS. In this
+  ** case none of the code in this module is executed as a result of calls
+  ** made on the journal file-handle.  */
+  memset(p, 0, sizeof(MemJournal));
+  if( nSpill==0 ){
+    return sqlite3OsOpen(pVfs, zName, pJfd, flags, 0);
+  }
+
+  if( nSpill>0 ){
+    p->nChunkSize = nSpill;
+  }else{
+    p->nChunkSize = 8 + MEMJOURNAL_DFLT_FILECHUNKSIZE - sizeof(FileChunk);
+    assert( MEMJOURNAL_DFLT_FILECHUNKSIZE==fileChunkSize(p->nChunkSize) );
+  }
+
+  p->pMethod = (const sqlite3_io_methods*)&MemJournalMethods;
+  p->nSpill = nSpill;
+  p->flags = flags;
+  p->zJournal = zName;
+  p->pVfs = pVfs;
+  return SQLITE_OK;
+}
+
+/*
+** Open an in-memory journal file.
+*/
+SQLITE_PRIVATE void sqlite3MemJournalOpen(sqlite3_file *pJfd){
+  sqlite3JournalOpen(0, 0, pJfd, 0, -1);
+}
+
+#ifdef SQLITE_ENABLE_ATOMIC_WRITE
+/*
+** If the argument p points to a MemJournal structure that is not an 
+** in-memory-only journal file (i.e. is one that was opened with a +ve
+** nSpill parameter), and the underlying file has not yet been created, 
+** create it now.
+*/
+SQLITE_PRIVATE int sqlite3JournalCreate(sqlite3_file *p){
+  int rc = SQLITE_OK;
+  if( p->pMethods==&MemJournalMethods && ((MemJournal*)p)->nSpill>0 ){
+    rc = memjrnlCreateFile((MemJournal*)p);
+  }
+  return rc;
+}
+#endif
+
+/*
+** The file-handle passed as the only argument is open on a journal file.
+** Return true if this "journal file" is currently stored in heap memory,
+** or false otherwise.
+*/
+SQLITE_PRIVATE int sqlite3JournalIsInMemory(sqlite3_file *p){
+  return p->pMethods==&MemJournalMethods;
+}
+
+/* 
+** Return the number of bytes required to store a JournalFile that uses vfs
+** pVfs to create the underlying on-disk files.
+*/
+SQLITE_PRIVATE int sqlite3JournalSize(sqlite3_vfs *pVfs){
+  return MAX(pVfs->szOsFile, (int)sizeof(MemJournal));
+}
+
+/************** End of memjournal.c ******************************************/
+/************** Begin file walker.c ******************************************/
+/*
+** 2008 August 16
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains routines used for walking the parser tree for
+** an SQL statement.
+*/
+/* #include "sqliteInt.h" */
+/* #include <stdlib.h> */
+/* #include <string.h> */
+
+
+/*
+** Walk an expression tree.  Invoke the callback once for each node
+** of the expression, while descending.  (In other words, the callback
+** is invoked before visiting children.)
+**
+** The return value from the callback should be one of the WRC_*
+** constants to specify how to proceed with the walk.
+**
+**    WRC_Continue      Continue descending down the tree.
+**
+**    WRC_Prune         Do not descend into child nodes.  But allow
+**                      the walk to continue with sibling nodes.
+**
+**    WRC_Abort         Do no more callbacks.  Unwind the stack and
+**                      return the top-level walk call.
+**
+** The return value from this routine is WRC_Abort to abandon the tree walk
+** and WRC_Continue to continue.
+*/
+static SQLITE_NOINLINE int walkExpr(Walker *pWalker, Expr *pExpr){
+  int rc;
+  testcase( ExprHasProperty(pExpr, EP_TokenOnly) );
+  testcase( ExprHasProperty(pExpr, EP_Reduced) );
+  rc = pWalker->xExprCallback(pWalker, pExpr);
+  if( rc || ExprHasProperty(pExpr,(EP_TokenOnly|EP_Leaf)) ){
+    return rc & WRC_Abort;
+  }
+  if( pExpr->pLeft && walkExpr(pWalker, pExpr->pLeft) ) return WRC_Abort;
+  if( pExpr->pRight && walkExpr(pWalker, pExpr->pRight) ) return WRC_Abort;
+  if( ExprHasProperty(pExpr, EP_xIsSelect) ){
+    if( sqlite3WalkSelect(pWalker, pExpr->x.pSelect) ) return WRC_Abort;
+  }else if( pExpr->x.pList ){
+    if( sqlite3WalkExprList(pWalker, pExpr->x.pList) ) return WRC_Abort;
+  }
+  return WRC_Continue;
+}
+SQLITE_PRIVATE int sqlite3WalkExpr(Walker *pWalker, Expr *pExpr){
+  return pExpr ? walkExpr(pWalker,pExpr) : WRC_Continue;
+}
+
+/*
+** Call sqlite3WalkExpr() for every expression in list p or until
+** an abort request is seen.
+*/
+SQLITE_PRIVATE int sqlite3WalkExprList(Walker *pWalker, ExprList *p){
+  int i;
+  struct ExprList_item *pItem;
+  if( p ){
+    for(i=p->nExpr, pItem=p->a; i>0; i--, pItem++){
+      if( sqlite3WalkExpr(pWalker, pItem->pExpr) ) return WRC_Abort;
+    }
+  }
+  return WRC_Continue;
+}
+
+/*
+** Walk all expressions associated with SELECT statement p.  Do
+** not invoke the SELECT callback on p, but do (of course) invoke
+** any expr callbacks and SELECT callbacks that come from subqueries.
+** Return WRC_Abort or WRC_Continue.
+*/
+SQLITE_PRIVATE int sqlite3WalkSelectExpr(Walker *pWalker, Select *p){
+  if( sqlite3WalkExprList(pWalker, p->pEList) ) return WRC_Abort;
+  if( sqlite3WalkExpr(pWalker, p->pWhere) ) return WRC_Abort;
+  if( sqlite3WalkExprList(pWalker, p->pGroupBy) ) return WRC_Abort;
+  if( sqlite3WalkExpr(pWalker, p->pHaving) ) return WRC_Abort;
+  if( sqlite3WalkExprList(pWalker, p->pOrderBy) ) return WRC_Abort;
+  if( sqlite3WalkExpr(pWalker, p->pLimit) ) return WRC_Abort;
+  if( sqlite3WalkExpr(pWalker, p->pOffset) ) return WRC_Abort;
+  return WRC_Continue;
+}
+
+/*
+** Walk the parse trees associated with all subqueries in the
+** FROM clause of SELECT statement p.  Do not invoke the select
+** callback on p, but do invoke it on each FROM clause subquery
+** and on any subqueries further down in the tree.  Return 
+** WRC_Abort or WRC_Continue;
+*/
+SQLITE_PRIVATE int sqlite3WalkSelectFrom(Walker *pWalker, Select *p){
+  SrcList *pSrc;
+  int i;
+  struct SrcList_item *pItem;
+
+  pSrc = p->pSrc;
+  if( ALWAYS(pSrc) ){
+    for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){
+      if( sqlite3WalkSelect(pWalker, pItem->pSelect) ){
+        return WRC_Abort;
+      }
+      if( pItem->fg.isTabFunc
+       && sqlite3WalkExprList(pWalker, pItem->u1.pFuncArg)
+      ){
+        return WRC_Abort;
+      }
+    }
+  }
+  return WRC_Continue;
+} 
+
+/*
+** Call sqlite3WalkExpr() for every expression in Select statement p.
+** Invoke sqlite3WalkSelect() for subqueries in the FROM clause and
+** on the compound select chain, p->pPrior. 
+**
+** If it is not NULL, the xSelectCallback() callback is invoked before
+** the walk of the expressions and FROM clause. The xSelectCallback2()
+** method, if it is not NULL, is invoked following the walk of the 
+** expressions and FROM clause.
+**
+** Return WRC_Continue under normal conditions.  Return WRC_Abort if
+** there is an abort request.
+**
+** If the Walker does not have an xSelectCallback() then this routine
+** is a no-op returning WRC_Continue.
+*/
+SQLITE_PRIVATE int sqlite3WalkSelect(Walker *pWalker, Select *p){
+  int rc;
+  if( p==0 || (pWalker->xSelectCallback==0 && pWalker->xSelectCallback2==0) ){
+    return WRC_Continue;
+  }
+  rc = WRC_Continue;
+  pWalker->walkerDepth++;
+  while( p ){
+    if( pWalker->xSelectCallback ){
+       rc = pWalker->xSelectCallback(pWalker, p);
+       if( rc ) break;
+    }
+    if( sqlite3WalkSelectExpr(pWalker, p)
+     || sqlite3WalkSelectFrom(pWalker, p)
+    ){
+      pWalker->walkerDepth--;
+      return WRC_Abort;
+    }
+    if( pWalker->xSelectCallback2 ){
+      pWalker->xSelectCallback2(pWalker, p);
+    }
+    p = p->pPrior;
+  }
+  pWalker->walkerDepth--;
+  return rc & WRC_Abort;
+}
+
+/************** End of walker.c **********************************************/
+/************** Begin file resolve.c *****************************************/
+/*
+** 2008 August 18
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains routines used for walking the parser tree and
+** resolve all identifiers by associating them with a particular
+** table and column.
+*/
+/* #include "sqliteInt.h" */
+/* #include <stdlib.h> */
+/* #include <string.h> */
+
+/*
+** Walk the expression tree pExpr and increase the aggregate function
+** depth (the Expr.op2 field) by N on every TK_AGG_FUNCTION node.
+** This needs to occur when copying a TK_AGG_FUNCTION node from an
+** outer query into an inner subquery.
+**
+** incrAggFunctionDepth(pExpr,n) is the main routine.  incrAggDepth(..)
+** is a helper function - a callback for the tree walker.
+*/
+static int incrAggDepth(Walker *pWalker, Expr *pExpr){
+  if( pExpr->op==TK_AGG_FUNCTION ) pExpr->op2 += pWalker->u.n;
+  return WRC_Continue;
+}
+static void incrAggFunctionDepth(Expr *pExpr, int N){
+  if( N>0 ){
+    Walker w;
+    memset(&w, 0, sizeof(w));
+    w.xExprCallback = incrAggDepth;
+    w.u.n = N;
+    sqlite3WalkExpr(&w, pExpr);
+  }
+}
+
+/*
+** Turn the pExpr expression into an alias for the iCol-th column of the
+** result set in pEList.
+**
+** If the reference is followed by a COLLATE operator, then make sure
+** the COLLATE operator is preserved.  For example:
+**
+**     SELECT a+b, c+d FROM t1 ORDER BY 1 COLLATE nocase;
+**
+** Should be transformed into:
+**
+**     SELECT a+b, c+d FROM t1 ORDER BY (a+b) COLLATE nocase;
+**
+** The nSubquery parameter specifies how many levels of subquery the
+** alias is removed from the original expression.  The usual value is
+** zero but it might be more if the alias is contained within a subquery
+** of the original expression.  The Expr.op2 field of TK_AGG_FUNCTION
+** structures must be increased by the nSubquery amount.
+*/
+static void resolveAlias(
+  Parse *pParse,         /* Parsing context */
+  ExprList *pEList,      /* A result set */
+  int iCol,              /* A column in the result set.  0..pEList->nExpr-1 */
+  Expr *pExpr,           /* Transform this into an alias to the result set */
+  const char *zType,     /* "GROUP" or "ORDER" or "" */
+  int nSubquery          /* Number of subqueries that the label is moving */
+){
+  Expr *pOrig;           /* The iCol-th column of the result set */
+  Expr *pDup;            /* Copy of pOrig */
+  sqlite3 *db;           /* The database connection */
+
+  assert( iCol>=0 && iCol<pEList->nExpr );
+  pOrig = pEList->a[iCol].pExpr;
+  assert( pOrig!=0 );
+  db = pParse->db;
+  pDup = sqlite3ExprDup(db, pOrig, 0);
+  if( pDup==0 ) return;
+  if( zType[0]!='G' ) incrAggFunctionDepth(pDup, nSubquery);
+  if( pExpr->op==TK_COLLATE ){
+    pDup = sqlite3ExprAddCollateString(pParse, pDup, pExpr->u.zToken);
+  }
+  ExprSetProperty(pDup, EP_Alias);
+
+  /* Before calling sqlite3ExprDelete(), set the EP_Static flag. This 
+  ** prevents ExprDelete() from deleting the Expr structure itself,
+  ** allowing it to be repopulated by the memcpy() on the following line.
+  ** The pExpr->u.zToken might point into memory that will be freed by the
+  ** sqlite3DbFree(db, pDup) on the last line of this block, so be sure to
+  ** make a copy of the token before doing the sqlite3DbFree().
+  */
+  ExprSetProperty(pExpr, EP_Static);
+  sqlite3ExprDelete(db, pExpr);
+  memcpy(pExpr, pDup, sizeof(*pExpr));
+  if( !ExprHasProperty(pExpr, EP_IntValue) && pExpr->u.zToken!=0 ){
+    assert( (pExpr->flags & (EP_Reduced|EP_TokenOnly))==0 );
+    pExpr->u.zToken = sqlite3DbStrDup(db, pExpr->u.zToken);
+    pExpr->flags |= EP_MemToken;
+  }
+  sqlite3DbFree(db, pDup);
+}
+
+
+/*
+** Return TRUE if the name zCol occurs anywhere in the USING clause.
+**
+** Return FALSE if the USING clause is NULL or if it does not contain
+** zCol.
+*/
+static int nameInUsingClause(IdList *pUsing, const char *zCol){
+  if( pUsing ){
+    int k;
+    for(k=0; k<pUsing->nId; k++){
+      if( sqlite3StrICmp(pUsing->a[k].zName, zCol)==0 ) return 1;
+    }
+  }
+  return 0;
+}
+
+/*
+** Subqueries stores the original database, table and column names for their
+** result sets in ExprList.a[].zSpan, in the form "DATABASE.TABLE.COLUMN".
+** Check to see if the zSpan given to this routine matches the zDb, zTab,
+** and zCol.  If any of zDb, zTab, and zCol are NULL then those fields will
+** match anything.
+*/
+SQLITE_PRIVATE int sqlite3MatchSpanName(
+  const char *zSpan,
+  const char *zCol,
+  const char *zTab,
+  const char *zDb
+){
+  int n;
+  for(n=0; ALWAYS(zSpan[n]) && zSpan[n]!='.'; n++){}
+  if( zDb && (sqlite3StrNICmp(zSpan, zDb, n)!=0 || zDb[n]!=0) ){
+    return 0;
+  }
+  zSpan += n+1;
+  for(n=0; ALWAYS(zSpan[n]) && zSpan[n]!='.'; n++){}
+  if( zTab && (sqlite3StrNICmp(zSpan, zTab, n)!=0 || zTab[n]!=0) ){
+    return 0;
+  }
+  zSpan += n+1;
+  if( zCol && sqlite3StrICmp(zSpan, zCol)!=0 ){
+    return 0;
+  }
+  return 1;
+}
+
+/*
+** Given the name of a column of the form X.Y.Z or Y.Z or just Z, look up
+** that name in the set of source tables in pSrcList and make the pExpr 
+** expression node refer back to that source column.  The following changes
+** are made to pExpr:
+**
+**    pExpr->iDb           Set the index in db->aDb[] of the database X
+**                         (even if X is implied).
+**    pExpr->iTable        Set to the cursor number for the table obtained
+**                         from pSrcList.
+**    pExpr->pTab          Points to the Table structure of X.Y (even if
+**                         X and/or Y are implied.)
+**    pExpr->iColumn       Set to the column number within the table.
+**    pExpr->op            Set to TK_COLUMN.
+**    pExpr->pLeft         Any expression this points to is deleted
+**    pExpr->pRight        Any expression this points to is deleted.
+**
+** The zDb variable is the name of the database (the "X").  This value may be
+** NULL meaning that name is of the form Y.Z or Z.  Any available database
+** can be used.  The zTable variable is the name of the table (the "Y").  This
+** value can be NULL if zDb is also NULL.  If zTable is NULL it
+** means that the form of the name is Z and that columns from any table
+** can be used.
+**
+** If the name cannot be resolved unambiguously, leave an error message
+** in pParse and return WRC_Abort.  Return WRC_Prune on success.
+*/
+static int lookupName(
+  Parse *pParse,       /* The parsing context */
+  const char *zDb,     /* Name of the database containing table, or NULL */
+  const char *zTab,    /* Name of table containing column, or NULL */
+  const char *zCol,    /* Name of the column. */
+  NameContext *pNC,    /* The name context used to resolve the name */
+  Expr *pExpr          /* Make this EXPR node point to the selected column */
+){
+  int i, j;                         /* Loop counters */
+  int cnt = 0;                      /* Number of matching column names */
+  int cntTab = 0;                   /* Number of matching table names */
+  int nSubquery = 0;                /* How many levels of subquery */
+  sqlite3 *db = pParse->db;         /* The database connection */
+  struct SrcList_item *pItem;       /* Use for looping over pSrcList items */
+  struct SrcList_item *pMatch = 0;  /* The matching pSrcList item */
+  NameContext *pTopNC = pNC;        /* First namecontext in the list */
+  Schema *pSchema = 0;              /* Schema of the expression */
+  int isTrigger = 0;                /* True if resolved to a trigger column */
+  Table *pTab = 0;                  /* Table hold the row */
+  Column *pCol;                     /* A column of pTab */
+
+  assert( pNC );     /* the name context cannot be NULL. */
+  assert( zCol );    /* The Z in X.Y.Z cannot be NULL */
+  assert( !ExprHasProperty(pExpr, EP_TokenOnly|EP_Reduced) );
+
+  /* Initialize the node to no-match */
+  pExpr->iTable = -1;
+  pExpr->pTab = 0;
+  ExprSetVVAProperty(pExpr, EP_NoReduce);
+
+  /* Translate the schema name in zDb into a pointer to the corresponding
+  ** schema.  If not found, pSchema will remain NULL and nothing will match
+  ** resulting in an appropriate error message toward the end of this routine
+  */
+  if( zDb ){
+    testcase( pNC->ncFlags & NC_PartIdx );
+    testcase( pNC->ncFlags & NC_IsCheck );
+    if( (pNC->ncFlags & (NC_PartIdx|NC_IsCheck))!=0 ){
+      /* Silently ignore database qualifiers inside CHECK constraints and
+      ** partial indices.  Do not raise errors because that might break
+      ** legacy and because it does not hurt anything to just ignore the
+      ** database name. */
+      zDb = 0;
+    }else{
+      for(i=0; i<db->nDb; i++){
+        assert( db->aDb[i].zDbSName );
+        if( sqlite3StrICmp(db->aDb[i].zDbSName,zDb)==0 ){
+          pSchema = db->aDb[i].pSchema;
+          break;
+        }
+      }
+    }
+  }
+
+  /* Start at the inner-most context and move outward until a match is found */
+  while( pNC && cnt==0 ){
+    ExprList *pEList;
+    SrcList *pSrcList = pNC->pSrcList;
+
+    if( pSrcList ){
+      for(i=0, pItem=pSrcList->a; i<pSrcList->nSrc; i++, pItem++){
+        pTab = pItem->pTab;
+        assert( pTab!=0 && pTab->zName!=0 );
+        assert( pTab->nCol>0 );
+        if( pItem->pSelect && (pItem->pSelect->selFlags & SF_NestedFrom)!=0 ){
+          int hit = 0;
+          pEList = pItem->pSelect->pEList;
+          for(j=0; j<pEList->nExpr; j++){
+            if( sqlite3MatchSpanName(pEList->a[j].zSpan, zCol, zTab, zDb) ){
+              cnt++;
+              cntTab = 2;
+              pMatch = pItem;
+              pExpr->iColumn = j;
+              hit = 1;
+            }
+          }
+          if( hit || zTab==0 ) continue;
+        }
+        if( zDb && pTab->pSchema!=pSchema ){
+          continue;
+        }
+        if( zTab ){
+          const char *zTabName = pItem->zAlias ? pItem->zAlias : pTab->zName;
+          assert( zTabName!=0 );
+          if( sqlite3StrICmp(zTabName, zTab)!=0 ){
+            continue;
+          }
+        }
+        if( 0==(cntTab++) ){
+          pMatch = pItem;
+        }
+        for(j=0, pCol=pTab->aCol; j<pTab->nCol; j++, pCol++){
+          if( sqlite3StrICmp(pCol->zName, zCol)==0 ){
+            /* If there has been exactly one prior match and this match
+            ** is for the right-hand table of a NATURAL JOIN or is in a 
+            ** USING clause, then skip this match.
+            */
+            if( cnt==1 ){
+              if( pItem->fg.jointype & JT_NATURAL ) continue;
+              if( nameInUsingClause(pItem->pUsing, zCol) ) continue;
+            }
+            cnt++;
+            pMatch = pItem;
+            /* Substitute the rowid (column -1) for the INTEGER PRIMARY KEY */
+            pExpr->iColumn = j==pTab->iPKey ? -1 : (i16)j;
+            break;
+          }
+        }
+      }
+      if( pMatch ){
+        pExpr->iTable = pMatch->iCursor;
+        pExpr->pTab = pMatch->pTab;
+        /* RIGHT JOIN not (yet) supported */
+        assert( (pMatch->fg.jointype & JT_RIGHT)==0 );
+        if( (pMatch->fg.jointype & JT_LEFT)!=0 ){
+          ExprSetProperty(pExpr, EP_CanBeNull);
+        }
+        pSchema = pExpr->pTab->pSchema;
+      }
+    } /* if( pSrcList ) */
+
+#ifndef SQLITE_OMIT_TRIGGER
+    /* If we have not already resolved the name, then maybe 
+    ** it is a new.* or old.* trigger argument reference
+    */
+    if( zDb==0 && zTab!=0 && cntTab==0 && pParse->pTriggerTab!=0 ){
+      int op = pParse->eTriggerOp;
+      assert( op==TK_DELETE || op==TK_UPDATE || op==TK_INSERT );
+      if( op!=TK_DELETE && sqlite3StrICmp("new",zTab) == 0 ){
+        pExpr->iTable = 1;
+        pTab = pParse->pTriggerTab;
+      }else if( op!=TK_INSERT && sqlite3StrICmp("old",zTab)==0 ){
+        pExpr->iTable = 0;
+        pTab = pParse->pTriggerTab;
+      }else{
+        pTab = 0;
+      }
+
+      if( pTab ){ 
+        int iCol;
+        pSchema = pTab->pSchema;
+        cntTab++;
+        for(iCol=0, pCol=pTab->aCol; iCol<pTab->nCol; iCol++, pCol++){
+          if( sqlite3StrICmp(pCol->zName, zCol)==0 ){
+            if( iCol==pTab->iPKey ){
+              iCol = -1;
+            }
+            break;
+          }
+        }
+        if( iCol>=pTab->nCol && sqlite3IsRowid(zCol) && VisibleRowid(pTab) ){
+          /* IMP: R-51414-32910 */
+          iCol = -1;
+        }
+        if( iCol<pTab->nCol ){
+          cnt++;
+          if( iCol<0 ){
+            pExpr->affinity = SQLITE_AFF_INTEGER;
+          }else if( pExpr->iTable==0 ){
+            testcase( iCol==31 );
+            testcase( iCol==32 );
+            pParse->oldmask |= (iCol>=32 ? 0xffffffff : (((u32)1)<<iCol));
+          }else{
+            testcase( iCol==31 );
+            testcase( iCol==32 );
+            pParse->newmask |= (iCol>=32 ? 0xffffffff : (((u32)1)<<iCol));
+          }
+          pExpr->iColumn = (i16)iCol;
+          pExpr->pTab = pTab;
+          isTrigger = 1;
+        }
+      }
+    }
+#endif /* !defined(SQLITE_OMIT_TRIGGER) */
+
+    /*
+    ** Perhaps the name is a reference to the ROWID
+    */
+    if( cnt==0
+     && cntTab==1
+     && pMatch
+     && (pNC->ncFlags & NC_IdxExpr)==0
+     && sqlite3IsRowid(zCol)
+     && VisibleRowid(pMatch->pTab)
+    ){
+      cnt = 1;
+      pExpr->iColumn = -1;
+      pExpr->affinity = SQLITE_AFF_INTEGER;
+    }
+
+    /*
+    ** If the input is of the form Z (not Y.Z or X.Y.Z) then the name Z
+    ** might refer to an result-set alias.  This happens, for example, when
+    ** we are resolving names in the WHERE clause of the following command:
+    **
+    **     SELECT a+b AS x FROM table WHERE x<10;
+    **
+    ** In cases like this, replace pExpr with a copy of the expression that
+    ** forms the result set entry ("a+b" in the example) and return immediately.
+    ** Note that the expression in the result set should have already been
+    ** resolved by the time the WHERE clause is resolved.
+    **
+    ** The ability to use an output result-set column in the WHERE, GROUP BY,
+    ** or HAVING clauses, or as part of a larger expression in the ORDER BY
+    ** clause is not standard SQL.  This is a (goofy) SQLite extension, that
+    ** is supported for backwards compatibility only. Hence, we issue a warning
+    ** on sqlite3_log() whenever the capability is used.
+    */
+    if( (pEList = pNC->pEList)!=0
+     && zTab==0
+     && cnt==0
+    ){
+      for(j=0; j<pEList->nExpr; j++){
+        char *zAs = pEList->a[j].zName;
+        if( zAs!=0 && sqlite3StrICmp(zAs, zCol)==0 ){
+          Expr *pOrig;
+          assert( pExpr->pLeft==0 && pExpr->pRight==0 );
+          assert( pExpr->x.pList==0 );
+          assert( pExpr->x.pSelect==0 );
+          pOrig = pEList->a[j].pExpr;
+          if( (pNC->ncFlags&NC_AllowAgg)==0 && ExprHasProperty(pOrig, EP_Agg) ){
+            sqlite3ErrorMsg(pParse, "misuse of aliased aggregate %s", zAs);
+            return WRC_Abort;
+          }
+          if( sqlite3ExprVectorSize(pOrig)!=1 ){
+            sqlite3ErrorMsg(pParse, "row value misused");
+            return WRC_Abort;
+          }
+          resolveAlias(pParse, pEList, j, pExpr, "", nSubquery);
+          cnt = 1;
+          pMatch = 0;
+          assert( zTab==0 && zDb==0 );
+          goto lookupname_end;
+        }
+      } 
+    }
+
+    /* Advance to the next name context.  The loop will exit when either
+    ** we have a match (cnt>0) or when we run out of name contexts.
+    */
+    if( cnt==0 ){
+      pNC = pNC->pNext;
+      nSubquery++;
+    }
+  }
+
+  /*
+  ** If X and Y are NULL (in other words if only the column name Z is
+  ** supplied) and the value of Z is enclosed in double-quotes, then
+  ** Z is a string literal if it doesn't match any column names.  In that
+  ** case, we need to return right away and not make any changes to
+  ** pExpr.
+  **
+  ** Because no reference was made to outer contexts, the pNC->nRef
+  ** fields are not changed in any context.
+  */
+  if( cnt==0 && zTab==0 && ExprHasProperty(pExpr,EP_DblQuoted) ){
+    pExpr->op = TK_STRING;
+    pExpr->pTab = 0;
+    return WRC_Prune;
+  }
+
+  /*
+  ** cnt==0 means there was not match.  cnt>1 means there were two or
+  ** more matches.  Either way, we have an error.
+  */
+  if( cnt!=1 ){
+    const char *zErr;
+    zErr = cnt==0 ? "no such column" : "ambiguous column name";
+    if( zDb ){
+      sqlite3ErrorMsg(pParse, "%s: %s.%s.%s", zErr, zDb, zTab, zCol);
+    }else if( zTab ){
+      sqlite3ErrorMsg(pParse, "%s: %s.%s", zErr, zTab, zCol);
+    }else{
+      sqlite3ErrorMsg(pParse, "%s: %s", zErr, zCol);
+    }
+    pParse->checkSchema = 1;
+    pTopNC->nErr++;
+  }
+
+  /* If a column from a table in pSrcList is referenced, then record
+  ** this fact in the pSrcList.a[].colUsed bitmask.  Column 0 causes
+  ** bit 0 to be set.  Column 1 sets bit 1.  And so forth.  If the
+  ** column number is greater than the number of bits in the bitmask
+  ** then set the high-order bit of the bitmask.
+  */
+  if( pExpr->iColumn>=0 && pMatch!=0 ){
+    int n = pExpr->iColumn;
+    testcase( n==BMS-1 );
+    if( n>=BMS ){
+      n = BMS-1;
+    }
+    assert( pMatch->iCursor==pExpr->iTable );
+    pMatch->colUsed |= ((Bitmask)1)<<n;
+  }
+
+  /* Clean up and return
+  */
+  sqlite3ExprDelete(db, pExpr->pLeft);
+  pExpr->pLeft = 0;
+  sqlite3ExprDelete(db, pExpr->pRight);
+  pExpr->pRight = 0;
+  pExpr->op = (isTrigger ? TK_TRIGGER : TK_COLUMN);
+lookupname_end:
+  if( cnt==1 ){
+    assert( pNC!=0 );
+    if( !ExprHasProperty(pExpr, EP_Alias) ){
+      sqlite3AuthRead(pParse, pExpr, pSchema, pNC->pSrcList);
+    }
+    /* Increment the nRef value on all name contexts from TopNC up to
+    ** the point where the name matched. */
+    for(;;){
+      assert( pTopNC!=0 );
+      pTopNC->nRef++;
+      if( pTopNC==pNC ) break;
+      pTopNC = pTopNC->pNext;
+    }
+    return WRC_Prune;
+  } else {
+    return WRC_Abort;
+  }
+}
+
+/*
+** Allocate and return a pointer to an expression to load the column iCol
+** from datasource iSrc in SrcList pSrc.
+*/
+SQLITE_PRIVATE Expr *sqlite3CreateColumnExpr(sqlite3 *db, SrcList *pSrc, int iSrc, int iCol){
+  Expr *p = sqlite3ExprAlloc(db, TK_COLUMN, 0, 0);
+  if( p ){
+    struct SrcList_item *pItem = &pSrc->a[iSrc];
+    p->pTab = pItem->pTab;
+    p->iTable = pItem->iCursor;
+    if( p->pTab->iPKey==iCol ){
+      p->iColumn = -1;
+    }else{
+      p->iColumn = (ynVar)iCol;
+      testcase( iCol==BMS );
+      testcase( iCol==BMS-1 );
+      pItem->colUsed |= ((Bitmask)1)<<(iCol>=BMS ? BMS-1 : iCol);
+    }
+    ExprSetProperty(p, EP_Resolved);
+  }
+  return p;
+}
+
+/*
+** Report an error that an expression is not valid for some set of
+** pNC->ncFlags values determined by validMask.
+*/
+static void notValid(
+  Parse *pParse,       /* Leave error message here */
+  NameContext *pNC,    /* The name context */
+  const char *zMsg,    /* Type of error */
+  int validMask        /* Set of contexts for which prohibited */
+){
+  assert( (validMask&~(NC_IsCheck|NC_PartIdx|NC_IdxExpr))==0 );
+  if( (pNC->ncFlags & validMask)!=0 ){
+    const char *zIn = "partial index WHERE clauses";
+    if( pNC->ncFlags & NC_IdxExpr )      zIn = "index expressions";
+#ifndef SQLITE_OMIT_CHECK
+    else if( pNC->ncFlags & NC_IsCheck ) zIn = "CHECK constraints";
+#endif
+    sqlite3ErrorMsg(pParse, "%s prohibited in %s", zMsg, zIn);
+  }
+}
+
+/*
+** Expression p should encode a floating point value between 1.0 and 0.0.
+** Return 1024 times this value.  Or return -1 if p is not a floating point
+** value between 1.0 and 0.0.
+*/
+static int exprProbability(Expr *p){
+  double r = -1.0;
+  if( p->op!=TK_FLOAT ) return -1;
+  sqlite3AtoF(p->u.zToken, &r, sqlite3Strlen30(p->u.zToken), SQLITE_UTF8);
+  assert( r>=0.0 );
+  if( r>1.0 ) return -1;
+  return (int)(r*134217728.0);
+}
+
+/*
+** This routine is callback for sqlite3WalkExpr().
+**
+** Resolve symbolic names into TK_COLUMN operators for the current
+** node in the expression tree.  Return 0 to continue the search down
+** the tree or 2 to abort the tree walk.
+**
+** This routine also does error checking and name resolution for
+** function names.  The operator for aggregate functions is changed
+** to TK_AGG_FUNCTION.
+*/
+static int resolveExprStep(Walker *pWalker, Expr *pExpr){
+  NameContext *pNC;
+  Parse *pParse;
+
+  pNC = pWalker->u.pNC;
+  assert( pNC!=0 );
+  pParse = pNC->pParse;
+  assert( pParse==pWalker->pParse );
+
+  if( ExprHasProperty(pExpr, EP_Resolved) ) return WRC_Prune;
+  ExprSetProperty(pExpr, EP_Resolved);
+#ifndef NDEBUG
+  if( pNC->pSrcList && pNC->pSrcList->nAlloc>0 ){
+    SrcList *pSrcList = pNC->pSrcList;
+    int i;
+    for(i=0; i<pNC->pSrcList->nSrc; i++){
+      assert( pSrcList->a[i].iCursor>=0 && pSrcList->a[i].iCursor<pParse->nTab);
+    }
+  }
+#endif
+  switch( pExpr->op ){
+
+#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)
+    /* The special operator TK_ROW means use the rowid for the first
+    ** column in the FROM clause.  This is used by the LIMIT and ORDER BY
+    ** clause processing on UPDATE and DELETE statements.
+    */
+    case TK_ROW: {
+      SrcList *pSrcList = pNC->pSrcList;
+      struct SrcList_item *pItem;
+      assert( pSrcList && pSrcList->nSrc==1 );
+      pItem = pSrcList->a; 
+      pExpr->op = TK_COLUMN;
+      pExpr->pTab = pItem->pTab;
+      pExpr->iTable = pItem->iCursor;
+      pExpr->iColumn = -1;
+      pExpr->affinity = SQLITE_AFF_INTEGER;
+      break;
+    }
+#endif /* defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT)
+          && !defined(SQLITE_OMIT_SUBQUERY) */
+
+    /* A lone identifier is the name of a column.
+    */
+    case TK_ID: {
+      return lookupName(pParse, 0, 0, pExpr->u.zToken, pNC, pExpr);
+    }
+  
+    /* A table name and column name:     ID.ID
+    ** Or a database, table and column:  ID.ID.ID
+    */
+    case TK_DOT: {
+      const char *zColumn;
+      const char *zTable;
+      const char *zDb;
+      Expr *pRight;
+
+      /* if( pSrcList==0 ) break; */
+      notValid(pParse, pNC, "the \".\" operator", NC_IdxExpr);
+      pRight = pExpr->pRight;
+      if( pRight->op==TK_ID ){
+        zDb = 0;
+        zTable = pExpr->pLeft->u.zToken;
+        zColumn = pRight->u.zToken;
+      }else{
+        assert( pRight->op==TK_DOT );
+        zDb = pExpr->pLeft->u.zToken;
+        zTable = pRight->pLeft->u.zToken;
+        zColumn = pRight->pRight->u.zToken;
+      }
+      return lookupName(pParse, zDb, zTable, zColumn, pNC, pExpr);
+    }
+
+    /* Resolve function names
+    */
+    case TK_FUNCTION: {
+      ExprList *pList = pExpr->x.pList;    /* The argument list */
+      int n = pList ? pList->nExpr : 0;    /* Number of arguments */
+      int no_such_func = 0;       /* True if no such function exists */
+      int wrong_num_args = 0;     /* True if wrong number of arguments */
+      int is_agg = 0;             /* True if is an aggregate function */
+      int nId;                    /* Number of characters in function name */
+      const char *zId;            /* The function name. */
+      FuncDef *pDef;              /* Information about the function */
+      u8 enc = ENC(pParse->db);   /* The database encoding */
+
+      assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
+      zId = pExpr->u.zToken;
+      nId = sqlite3Strlen30(zId);
+      pDef = sqlite3FindFunction(pParse->db, zId, n, enc, 0);
+      if( pDef==0 ){
+        pDef = sqlite3FindFunction(pParse->db, zId, -2, enc, 0);
+        if( pDef==0 ){
+          no_such_func = 1;
+        }else{
+          wrong_num_args = 1;
+        }
+      }else{
+        is_agg = pDef->xFinalize!=0;
+        if( pDef->funcFlags & SQLITE_FUNC_UNLIKELY ){
+          ExprSetProperty(pExpr, EP_Unlikely|EP_Skip);
+          if( n==2 ){
+            pExpr->iTable = exprProbability(pList->a[1].pExpr);
+            if( pExpr->iTable<0 ){
+              sqlite3ErrorMsg(pParse,
+                "second argument to likelihood() must be a "
+                "constant between 0.0 and 1.0");
+              pNC->nErr++;
+            }
+          }else{
+            /* EVIDENCE-OF: R-61304-29449 The unlikely(X) function is
+            ** equivalent to likelihood(X, 0.0625).
+            ** EVIDENCE-OF: R-01283-11636 The unlikely(X) function is
+            ** short-hand for likelihood(X,0.0625).
+            ** EVIDENCE-OF: R-36850-34127 The likely(X) function is short-hand
+            ** for likelihood(X,0.9375).
+            ** EVIDENCE-OF: R-53436-40973 The likely(X) function is equivalent
+            ** to likelihood(X,0.9375). */
+            /* TUNING: unlikely() probability is 0.0625.  likely() is 0.9375 */
+            pExpr->iTable = pDef->zName[0]=='u' ? 8388608 : 125829120;
+          }             
+        }
+#ifndef SQLITE_OMIT_AUTHORIZATION
+        {
+          int auth = sqlite3AuthCheck(pParse, SQLITE_FUNCTION, 0,pDef->zName,0);
+          if( auth!=SQLITE_OK ){
+            if( auth==SQLITE_DENY ){
+              sqlite3ErrorMsg(pParse, "not authorized to use function: %s",
+                                      pDef->zName);
+              pNC->nErr++;
+            }
+            pExpr->op = TK_NULL;
+            return WRC_Prune;
+          }
+        }
+#endif
+        if( pDef->funcFlags & (SQLITE_FUNC_CONSTANT|SQLITE_FUNC_SLOCHNG) ){
+          /* For the purposes of the EP_ConstFunc flag, date and time
+          ** functions and other functions that change slowly are considered
+          ** constant because they are constant for the duration of one query */
+          ExprSetProperty(pExpr,EP_ConstFunc);
+        }
+        if( (pDef->funcFlags & SQLITE_FUNC_CONSTANT)==0 ){
+          /* Date/time functions that use 'now', and other functions like
+          ** sqlite_version() that might change over time cannot be used
+          ** in an index. */
+          notValid(pParse, pNC, "non-deterministic functions",
+                   NC_IdxExpr|NC_PartIdx);
+        }
+      }
+      if( is_agg && (pNC->ncFlags & NC_AllowAgg)==0 ){
+        sqlite3ErrorMsg(pParse, "misuse of aggregate function %.*s()", nId,zId);
+        pNC->nErr++;
+        is_agg = 0;
+      }else if( no_such_func && pParse->db->init.busy==0
+#ifdef SQLITE_ENABLE_UNKNOWN_SQL_FUNCTION
+                && pParse->explain==0
+#endif
+      ){
+        sqlite3ErrorMsg(pParse, "no such function: %.*s", nId, zId);
+        pNC->nErr++;
+      }else if( wrong_num_args ){
+        sqlite3ErrorMsg(pParse,"wrong number of arguments to function %.*s()",
+             nId, zId);
+        pNC->nErr++;
+      }
+      if( is_agg ) pNC->ncFlags &= ~NC_AllowAgg;
+      sqlite3WalkExprList(pWalker, pList);
+      if( is_agg ){
+        NameContext *pNC2 = pNC;
+        pExpr->op = TK_AGG_FUNCTION;
+        pExpr->op2 = 0;
+        while( pNC2 && !sqlite3FunctionUsesThisSrc(pExpr, pNC2->pSrcList) ){
+          pExpr->op2++;
+          pNC2 = pNC2->pNext;
+        }
+        assert( pDef!=0 );
+        if( pNC2 ){
+          assert( SQLITE_FUNC_MINMAX==NC_MinMaxAgg );
+          testcase( (pDef->funcFlags & SQLITE_FUNC_MINMAX)!=0 );
+          pNC2->ncFlags |= NC_HasAgg | (pDef->funcFlags & SQLITE_FUNC_MINMAX);
+
+        }
+        pNC->ncFlags |= NC_AllowAgg;
+      }
+      /* FIX ME:  Compute pExpr->affinity based on the expected return
+      ** type of the function 
+      */
+      return WRC_Prune;
+    }
+#ifndef SQLITE_OMIT_SUBQUERY
+    case TK_SELECT:
+    case TK_EXISTS:  testcase( pExpr->op==TK_EXISTS );
+#endif
+    case TK_IN: {
+      testcase( pExpr->op==TK_IN );
+      if( ExprHasProperty(pExpr, EP_xIsSelect) ){
+        int nRef = pNC->nRef;
+        notValid(pParse, pNC, "subqueries", NC_IsCheck|NC_PartIdx|NC_IdxExpr);
+        sqlite3WalkSelect(pWalker, pExpr->x.pSelect);
+        assert( pNC->nRef>=nRef );
+        if( nRef!=pNC->nRef ){
+          ExprSetProperty(pExpr, EP_VarSelect);
+          pNC->ncFlags |= NC_VarSelect;
+        }
+      }
+      break;
+    }
+    case TK_VARIABLE: {
+      notValid(pParse, pNC, "parameters", NC_IsCheck|NC_PartIdx|NC_IdxExpr);
+      break;
+    }
+    case TK_BETWEEN:
+    case TK_EQ:
+    case TK_NE:
+    case TK_LT:
+    case TK_LE:
+    case TK_GT:
+    case TK_GE:
+    case TK_IS:
+    case TK_ISNOT: {
+      int nLeft, nRight;
+      if( pParse->db->mallocFailed ) break;
+      assert( pExpr->pLeft!=0 );
+      nLeft = sqlite3ExprVectorSize(pExpr->pLeft);
+      if( pExpr->op==TK_BETWEEN ){
+        nRight = sqlite3ExprVectorSize(pExpr->x.pList->a[0].pExpr);
+        if( nRight==nLeft ){
+          nRight = sqlite3ExprVectorSize(pExpr->x.pList->a[1].pExpr);
+        }
+      }else{
+        assert( pExpr->pRight!=0 );
+        nRight = sqlite3ExprVectorSize(pExpr->pRight);
+      }
+      if( nLeft!=nRight ){
+        testcase( pExpr->op==TK_EQ );
+        testcase( pExpr->op==TK_NE );
+        testcase( pExpr->op==TK_LT );
+        testcase( pExpr->op==TK_LE );
+        testcase( pExpr->op==TK_GT );
+        testcase( pExpr->op==TK_GE );
+        testcase( pExpr->op==TK_IS );
+        testcase( pExpr->op==TK_ISNOT );
+        testcase( pExpr->op==TK_BETWEEN );
+        sqlite3ErrorMsg(pParse, "row value misused");
+      }
+      break; 
+    }
+  }
+  return (pParse->nErr || pParse->db->mallocFailed) ? WRC_Abort : WRC_Continue;
+}
+
+/*
+** pEList is a list of expressions which are really the result set of the
+** a SELECT statement.  pE is a term in an ORDER BY or GROUP BY clause.
+** This routine checks to see if pE is a simple identifier which corresponds
+** to the AS-name of one of the terms of the expression list.  If it is,
+** this routine return an integer between 1 and N where N is the number of
+** elements in pEList, corresponding to the matching entry.  If there is
+** no match, or if pE is not a simple identifier, then this routine
+** return 0.
+**
+** pEList has been resolved.  pE has not.
+*/
+static int resolveAsName(
+  Parse *pParse,     /* Parsing context for error messages */
+  ExprList *pEList,  /* List of expressions to scan */
+  Expr *pE           /* Expression we are trying to match */
+){
+  int i;             /* Loop counter */
+
+  UNUSED_PARAMETER(pParse);
+
+  if( pE->op==TK_ID ){
+    char *zCol = pE->u.zToken;
+    for(i=0; i<pEList->nExpr; i++){
+      char *zAs = pEList->a[i].zName;
+      if( zAs!=0 && sqlite3StrICmp(zAs, zCol)==0 ){
+        return i+1;
+      }
+    }
+  }
+  return 0;
+}
+
+/*
+** pE is a pointer to an expression which is a single term in the
+** ORDER BY of a compound SELECT.  The expression has not been
+** name resolved.
+**
+** At the point this routine is called, we already know that the
+** ORDER BY term is not an integer index into the result set.  That
+** case is handled by the calling routine.
+**
+** Attempt to match pE against result set columns in the left-most
+** SELECT statement.  Return the index i of the matching column,
+** as an indication to the caller that it should sort by the i-th column.
+** The left-most column is 1.  In other words, the value returned is the
+** same integer value that would be used in the SQL statement to indicate
+** the column.
+**
+** If there is no match, return 0.  Return -1 if an error occurs.
+*/
+static int resolveOrderByTermToExprList(
+  Parse *pParse,     /* Parsing context for error messages */
+  Select *pSelect,   /* The SELECT statement with the ORDER BY clause */
+  Expr *pE           /* The specific ORDER BY term */
+){
+  int i;             /* Loop counter */
+  ExprList *pEList;  /* The columns of the result set */
+  NameContext nc;    /* Name context for resolving pE */
+  sqlite3 *db;       /* Database connection */
+  int rc;            /* Return code from subprocedures */
+  u8 savedSuppErr;   /* Saved value of db->suppressErr */
+
+  assert( sqlite3ExprIsInteger(pE, &i)==0 );
+  pEList = pSelect->pEList;
+
+  /* Resolve all names in the ORDER BY term expression
+  */
+  memset(&nc, 0, sizeof(nc));
+  nc.pParse = pParse;
+  nc.pSrcList = pSelect->pSrc;
+  nc.pEList = pEList;
+  nc.ncFlags = NC_AllowAgg;
+  nc.nErr = 0;
+  db = pParse->db;
+  savedSuppErr = db->suppressErr;
+  db->suppressErr = 1;
+  rc = sqlite3ResolveExprNames(&nc, pE);
+  db->suppressErr = savedSuppErr;
+  if( rc ) return 0;
+
+  /* Try to match the ORDER BY expression against an expression
+  ** in the result set.  Return an 1-based index of the matching
+  ** result-set entry.
+  */
+  for(i=0; i<pEList->nExpr; i++){
+    if( sqlite3ExprCompare(pEList->a[i].pExpr, pE, -1)<2 ){
+      return i+1;
+    }
+  }
+
+  /* If no match, return 0. */
+  return 0;
+}
+
+/*
+** Generate an ORDER BY or GROUP BY term out-of-range error.
+*/
+static void resolveOutOfRangeError(
+  Parse *pParse,         /* The error context into which to write the error */
+  const char *zType,     /* "ORDER" or "GROUP" */
+  int i,                 /* The index (1-based) of the term out of range */
+  int mx                 /* Largest permissible value of i */
+){
+  sqlite3ErrorMsg(pParse, 
+    "%r %s BY term out of range - should be "
+    "between 1 and %d", i, zType, mx);
+}
+
+/*
+** Analyze the ORDER BY clause in a compound SELECT statement.   Modify
+** each term of the ORDER BY clause is a constant integer between 1
+** and N where N is the number of columns in the compound SELECT.
+**
+** ORDER BY terms that are already an integer between 1 and N are
+** unmodified.  ORDER BY terms that are integers outside the range of
+** 1 through N generate an error.  ORDER BY terms that are expressions
+** are matched against result set expressions of compound SELECT
+** beginning with the left-most SELECT and working toward the right.
+** At the first match, the ORDER BY expression is transformed into
+** the integer column number.
+**
+** Return the number of errors seen.
+*/
+static int resolveCompoundOrderBy(
+  Parse *pParse,        /* Parsing context.  Leave error messages here */
+  Select *pSelect       /* The SELECT statement containing the ORDER BY */
+){
+  int i;
+  ExprList *pOrderBy;
+  ExprList *pEList;
+  sqlite3 *db;
+  int moreToDo = 1;
+
+  pOrderBy = pSelect->pOrderBy;
+  if( pOrderBy==0 ) return 0;
+  db = pParse->db;
+#if SQLITE_MAX_COLUMN
+  if( pOrderBy->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){
+    sqlite3ErrorMsg(pParse, "too many terms in ORDER BY clause");
+    return 1;
+  }
+#endif
+  for(i=0; i<pOrderBy->nExpr; i++){
+    pOrderBy->a[i].done = 0;
+  }
+  pSelect->pNext = 0;
+  while( pSelect->pPrior ){
+    pSelect->pPrior->pNext = pSelect;
+    pSelect = pSelect->pPrior;
+  }
+  while( pSelect && moreToDo ){
+    struct ExprList_item *pItem;
+    moreToDo = 0;
+    pEList = pSelect->pEList;
+    assert( pEList!=0 );
+    for(i=0, pItem=pOrderBy->a; i<pOrderBy->nExpr; i++, pItem++){
+      int iCol = -1;
+      Expr *pE, *pDup;
+      if( pItem->done ) continue;
+      pE = sqlite3ExprSkipCollate(pItem->pExpr);
+      if( sqlite3ExprIsInteger(pE, &iCol) ){
+        if( iCol<=0 || iCol>pEList->nExpr ){
+          resolveOutOfRangeError(pParse, "ORDER", i+1, pEList->nExpr);
+          return 1;
+        }
+      }else{
+        iCol = resolveAsName(pParse, pEList, pE);
+        if( iCol==0 ){
+          pDup = sqlite3ExprDup(db, pE, 0);
+          if( !db->mallocFailed ){
+            assert(pDup);
+            iCol = resolveOrderByTermToExprList(pParse, pSelect, pDup);
+          }
+          sqlite3ExprDelete(db, pDup);
+        }
+      }
+      if( iCol>0 ){
+        /* Convert the ORDER BY term into an integer column number iCol,
+        ** taking care to preserve the COLLATE clause if it exists */
+        Expr *pNew = sqlite3Expr(db, TK_INTEGER, 0);
+        if( pNew==0 ) return 1;
+        pNew->flags |= EP_IntValue;
+        pNew->u.iValue = iCol;
+        if( pItem->pExpr==pE ){
+          pItem->pExpr = pNew;
+        }else{
+          Expr *pParent = pItem->pExpr;
+          assert( pParent->op==TK_COLLATE );
+          while( pParent->pLeft->op==TK_COLLATE ) pParent = pParent->pLeft;
+          assert( pParent->pLeft==pE );
+          pParent->pLeft = pNew;
+        }
+        sqlite3ExprDelete(db, pE);
+        pItem->u.x.iOrderByCol = (u16)iCol;
+        pItem->done = 1;
+      }else{
+        moreToDo = 1;
+      }
+    }
+    pSelect = pSelect->pNext;
+  }
+  for(i=0; i<pOrderBy->nExpr; i++){
+    if( pOrderBy->a[i].done==0 ){
+      sqlite3ErrorMsg(pParse, "%r ORDER BY term does not match any "
+            "column in the result set", i+1);
+      return 1;
+    }
+  }
+  return 0;
+}
+
+/*
+** Check every term in the ORDER BY or GROUP BY clause pOrderBy of
+** the SELECT statement pSelect.  If any term is reference to a
+** result set expression (as determined by the ExprList.a.u.x.iOrderByCol
+** field) then convert that term into a copy of the corresponding result set
+** column.
+**
+** If any errors are detected, add an error message to pParse and
+** return non-zero.  Return zero if no errors are seen.
+*/
+SQLITE_PRIVATE int sqlite3ResolveOrderGroupBy(
+  Parse *pParse,        /* Parsing context.  Leave error messages here */
+  Select *pSelect,      /* The SELECT statement containing the clause */
+  ExprList *pOrderBy,   /* The ORDER BY or GROUP BY clause to be processed */
+  const char *zType     /* "ORDER" or "GROUP" */
+){
+  int i;
+  sqlite3 *db = pParse->db;
+  ExprList *pEList;
+  struct ExprList_item *pItem;
+
+  if( pOrderBy==0 || pParse->db->mallocFailed ) return 0;
+#if SQLITE_MAX_COLUMN
+  if( pOrderBy->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){
+    sqlite3ErrorMsg(pParse, "too many terms in %s BY clause", zType);
+    return 1;
+  }
+#endif
+  pEList = pSelect->pEList;
+  assert( pEList!=0 );  /* sqlite3SelectNew() guarantees this */
+  for(i=0, pItem=pOrderBy->a; i<pOrderBy->nExpr; i++, pItem++){
+    if( pItem->u.x.iOrderByCol ){
+      if( pItem->u.x.iOrderByCol>pEList->nExpr ){
+        resolveOutOfRangeError(pParse, zType, i+1, pEList->nExpr);
+        return 1;
+      }
+      resolveAlias(pParse, pEList, pItem->u.x.iOrderByCol-1, pItem->pExpr,
+                   zType,0);
+    }
+  }
+  return 0;
+}
+
+/*
+** pOrderBy is an ORDER BY or GROUP BY clause in SELECT statement pSelect.
+** The Name context of the SELECT statement is pNC.  zType is either
+** "ORDER" or "GROUP" depending on which type of clause pOrderBy is.
+**
+** This routine resolves each term of the clause into an expression.
+** If the order-by term is an integer I between 1 and N (where N is the
+** number of columns in the result set of the SELECT) then the expression
+** in the resolution is a copy of the I-th result-set expression.  If
+** the order-by term is an identifier that corresponds to the AS-name of
+** a result-set expression, then the term resolves to a copy of the
+** result-set expression.  Otherwise, the expression is resolved in
+** the usual way - using sqlite3ResolveExprNames().
+**
+** This routine returns the number of errors.  If errors occur, then
+** an appropriate error message might be left in pParse.  (OOM errors
+** excepted.)
+*/
+static int resolveOrderGroupBy(
+  NameContext *pNC,     /* The name context of the SELECT statement */
+  Select *pSelect,      /* The SELECT statement holding pOrderBy */
+  ExprList *pOrderBy,   /* An ORDER BY or GROUP BY clause to resolve */
+  const char *zType     /* Either "ORDER" or "GROUP", as appropriate */
+){
+  int i, j;                      /* Loop counters */
+  int iCol;                      /* Column number */
+  struct ExprList_item *pItem;   /* A term of the ORDER BY clause */
+  Parse *pParse;                 /* Parsing context */
+  int nResult;                   /* Number of terms in the result set */
+
+  if( pOrderBy==0 ) return 0;
+  nResult = pSelect->pEList->nExpr;
+  pParse = pNC->pParse;
+  for(i=0, pItem=pOrderBy->a; i<pOrderBy->nExpr; i++, pItem++){
+    Expr *pE = pItem->pExpr;
+    Expr *pE2 = sqlite3ExprSkipCollate(pE);
+    if( zType[0]!='G' ){
+      iCol = resolveAsName(pParse, pSelect->pEList, pE2);
+      if( iCol>0 ){
+        /* If an AS-name match is found, mark this ORDER BY column as being
+        ** a copy of the iCol-th result-set column.  The subsequent call to
+        ** sqlite3ResolveOrderGroupBy() will convert the expression to a
+        ** copy of the iCol-th result-set expression. */
+        pItem->u.x.iOrderByCol = (u16)iCol;
+        continue;
+      }
+    }
+    if( sqlite3ExprIsInteger(pE2, &iCol) ){
+      /* The ORDER BY term is an integer constant.  Again, set the column
+      ** number so that sqlite3ResolveOrderGroupBy() will convert the
+      ** order-by term to a copy of the result-set expression */
+      if( iCol<1 || iCol>0xffff ){
+        resolveOutOfRangeError(pParse, zType, i+1, nResult);
+        return 1;
+      }
+      pItem->u.x.iOrderByCol = (u16)iCol;
+      continue;
+    }
+
+    /* Otherwise, treat the ORDER BY term as an ordinary expression */
+    pItem->u.x.iOrderByCol = 0;
+    if( sqlite3ResolveExprNames(pNC, pE) ){
+      return 1;
+    }
+    for(j=0; j<pSelect->pEList->nExpr; j++){
+      if( sqlite3ExprCompare(pE, pSelect->pEList->a[j].pExpr, -1)==0 ){
+        pItem->u.x.iOrderByCol = j+1;
+      }
+    }
+  }
+  return sqlite3ResolveOrderGroupBy(pParse, pSelect, pOrderBy, zType);
+}
+
+/*
+** Resolve names in the SELECT statement p and all of its descendants.
+*/
+static int resolveSelectStep(Walker *pWalker, Select *p){
+  NameContext *pOuterNC;  /* Context that contains this SELECT */
+  NameContext sNC;        /* Name context of this SELECT */
+  int isCompound;         /* True if p is a compound select */
+  int nCompound;          /* Number of compound terms processed so far */
+  Parse *pParse;          /* Parsing context */
+  int i;                  /* Loop counter */
+  ExprList *pGroupBy;     /* The GROUP BY clause */
+  Select *pLeftmost;      /* Left-most of SELECT of a compound */
+  sqlite3 *db;            /* Database connection */
+  
+
+  assert( p!=0 );
+  if( p->selFlags & SF_Resolved ){
+    return WRC_Prune;
+  }
+  pOuterNC = pWalker->u.pNC;
+  pParse = pWalker->pParse;
+  db = pParse->db;
+
+  /* Normally sqlite3SelectExpand() will be called first and will have
+  ** already expanded this SELECT.  However, if this is a subquery within
+  ** an expression, sqlite3ResolveExprNames() will be called without a
+  ** prior call to sqlite3SelectExpand().  When that happens, let
+  ** sqlite3SelectPrep() do all of the processing for this SELECT.
+  ** sqlite3SelectPrep() will invoke both sqlite3SelectExpand() and
+  ** this routine in the correct order.
+  */
+  if( (p->selFlags & SF_Expanded)==0 ){
+    sqlite3SelectPrep(pParse, p, pOuterNC);
+    return (pParse->nErr || db->mallocFailed) ? WRC_Abort : WRC_Prune;
+  }
+
+  isCompound = p->pPrior!=0;
+  nCompound = 0;
+  pLeftmost = p;
+  while( p ){
+    assert( (p->selFlags & SF_Expanded)!=0 );
+    assert( (p->selFlags & SF_Resolved)==0 );
+    p->selFlags |= SF_Resolved;
+
+    /* Resolve the expressions in the LIMIT and OFFSET clauses. These
+    ** are not allowed to refer to any names, so pass an empty NameContext.
+    */
+    memset(&sNC, 0, sizeof(sNC));
+    sNC.pParse = pParse;
+    if( sqlite3ResolveExprNames(&sNC, p->pLimit) ||
+        sqlite3ResolveExprNames(&sNC, p->pOffset) ){
+      return WRC_Abort;
+    }
+
+    /* If the SF_Converted flags is set, then this Select object was
+    ** was created by the convertCompoundSelectToSubquery() function.
+    ** In this case the ORDER BY clause (p->pOrderBy) should be resolved
+    ** as if it were part of the sub-query, not the parent. This block
+    ** moves the pOrderBy down to the sub-query. It will be moved back
+    ** after the names have been resolved.  */
+    if( p->selFlags & SF_Converted ){
+      Select *pSub = p->pSrc->a[0].pSelect;
+      assert( p->pSrc->nSrc==1 && p->pOrderBy );
+      assert( pSub->pPrior && pSub->pOrderBy==0 );
+      pSub->pOrderBy = p->pOrderBy;
+      p->pOrderBy = 0;
+    }
+  
+    /* Recursively resolve names in all subqueries
+    */
+    for(i=0; i<p->pSrc->nSrc; i++){
+      struct SrcList_item *pItem = &p->pSrc->a[i];
+      if( pItem->pSelect ){
+        NameContext *pNC;         /* Used to iterate name contexts */
+        int nRef = 0;             /* Refcount for pOuterNC and outer contexts */
+        const char *zSavedContext = pParse->zAuthContext;
+
+        /* Count the total number of references to pOuterNC and all of its
+        ** parent contexts. After resolving references to expressions in
+        ** pItem->pSelect, check if this value has changed. If so, then
+        ** SELECT statement pItem->pSelect must be correlated. Set the
+        ** pItem->fg.isCorrelated flag if this is the case. */
+        for(pNC=pOuterNC; pNC; pNC=pNC->pNext) nRef += pNC->nRef;
+
+        if( pItem->zName ) pParse->zAuthContext = pItem->zName;
+        sqlite3ResolveSelectNames(pParse, pItem->pSelect, pOuterNC);
+        pParse->zAuthContext = zSavedContext;
+        if( pParse->nErr || db->mallocFailed ) return WRC_Abort;
+
+        for(pNC=pOuterNC; pNC; pNC=pNC->pNext) nRef -= pNC->nRef;
+        assert( pItem->fg.isCorrelated==0 && nRef<=0 );
+        pItem->fg.isCorrelated = (nRef!=0);
+      }
+    }
+  
+    /* Set up the local name-context to pass to sqlite3ResolveExprNames() to
+    ** resolve the result-set expression list.
+    */
+    sNC.ncFlags = NC_AllowAgg;
+    sNC.pSrcList = p->pSrc;
+    sNC.pNext = pOuterNC;
+  
+    /* Resolve names in the result set. */
+    if( sqlite3ResolveExprListNames(&sNC, p->pEList) ) return WRC_Abort;
+  
+    /* If there are no aggregate functions in the result-set, and no GROUP BY 
+    ** expression, do not allow aggregates in any of the other expressions.
+    */
+    assert( (p->selFlags & SF_Aggregate)==0 );
+    pGroupBy = p->pGroupBy;
+    if( pGroupBy || (sNC.ncFlags & NC_HasAgg)!=0 ){
+      assert( NC_MinMaxAgg==SF_MinMaxAgg );
+      p->selFlags |= SF_Aggregate | (sNC.ncFlags&NC_MinMaxAgg);
+    }else{
+      sNC.ncFlags &= ~NC_AllowAgg;
+    }
+  
+    /* If a HAVING clause is present, then there must be a GROUP BY clause.
+    */
+    if( p->pHaving && !pGroupBy ){
+      sqlite3ErrorMsg(pParse, "a GROUP BY clause is required before HAVING");
+      return WRC_Abort;
+    }
+  
+    /* Add the output column list to the name-context before parsing the
+    ** other expressions in the SELECT statement. This is so that
+    ** expressions in the WHERE clause (etc.) can refer to expressions by
+    ** aliases in the result set.
+    **
+    ** Minor point: If this is the case, then the expression will be
+    ** re-evaluated for each reference to it.
+    */
+    sNC.pEList = p->pEList;
+    if( sqlite3ResolveExprNames(&sNC, p->pHaving) ) return WRC_Abort;
+    if( sqlite3ResolveExprNames(&sNC, p->pWhere) ) return WRC_Abort;
+
+    /* Resolve names in table-valued-function arguments */
+    for(i=0; i<p->pSrc->nSrc; i++){
+      struct SrcList_item *pItem = &p->pSrc->a[i];
+      if( pItem->fg.isTabFunc
+       && sqlite3ResolveExprListNames(&sNC, pItem->u1.pFuncArg) 
+      ){
+        return WRC_Abort;
+      }
+    }
+
+    /* The ORDER BY and GROUP BY clauses may not refer to terms in
+    ** outer queries 
+    */
+    sNC.pNext = 0;
+    sNC.ncFlags |= NC_AllowAgg;
+
+    /* If this is a converted compound query, move the ORDER BY clause from 
+    ** the sub-query back to the parent query. At this point each term
+    ** within the ORDER BY clause has been transformed to an integer value.
+    ** These integers will be replaced by copies of the corresponding result
+    ** set expressions by the call to resolveOrderGroupBy() below.  */
+    if( p->selFlags & SF_Converted ){
+      Select *pSub = p->pSrc->a[0].pSelect;
+      p->pOrderBy = pSub->pOrderBy;
+      pSub->pOrderBy = 0;
+    }
+
+    /* Process the ORDER BY clause for singleton SELECT statements.
+    ** The ORDER BY clause for compounds SELECT statements is handled
+    ** below, after all of the result-sets for all of the elements of
+    ** the compound have been resolved.
+    **
+    ** If there is an ORDER BY clause on a term of a compound-select other
+    ** than the right-most term, then that is a syntax error.  But the error
+    ** is not detected until much later, and so we need to go ahead and
+    ** resolve those symbols on the incorrect ORDER BY for consistency.
+    */
+    if( isCompound<=nCompound  /* Defer right-most ORDER BY of a compound */
+     && resolveOrderGroupBy(&sNC, p, p->pOrderBy, "ORDER")
+    ){
+      return WRC_Abort;
+    }
+    if( db->mallocFailed ){
+      return WRC_Abort;
+    }
+  
+    /* Resolve the GROUP BY clause.  At the same time, make sure 
+    ** the GROUP BY clause does not contain aggregate functions.
+    */
+    if( pGroupBy ){
+      struct ExprList_item *pItem;
+    
+      if( resolveOrderGroupBy(&sNC, p, pGroupBy, "GROUP") || db->mallocFailed ){
+        return WRC_Abort;
+      }
+      for(i=0, pItem=pGroupBy->a; i<pGroupBy->nExpr; i++, pItem++){
+        if( ExprHasProperty(pItem->pExpr, EP_Agg) ){
+          sqlite3ErrorMsg(pParse, "aggregate functions are not allowed in "
+              "the GROUP BY clause");
+          return WRC_Abort;
+        }
+      }
+    }
+
+    /* If this is part of a compound SELECT, check that it has the right
+    ** number of expressions in the select list. */
+    if( p->pNext && p->pEList->nExpr!=p->pNext->pEList->nExpr ){
+      sqlite3SelectWrongNumTermsError(pParse, p->pNext);
+      return WRC_Abort;
+    }
+
+    /* Advance to the next term of the compound
+    */
+    p = p->pPrior;
+    nCompound++;
+  }
+
+  /* Resolve the ORDER BY on a compound SELECT after all terms of
+  ** the compound have been resolved.
+  */
+  if( isCompound && resolveCompoundOrderBy(pParse, pLeftmost) ){
+    return WRC_Abort;
+  }
+
+  return WRC_Prune;
+}
+
+/*
+** This routine walks an expression tree and resolves references to
+** table columns and result-set columns.  At the same time, do error
+** checking on function usage and set a flag if any aggregate functions
+** are seen.
+**
+** To resolve table columns references we look for nodes (or subtrees) of the 
+** form X.Y.Z or Y.Z or just Z where
+**
+**      X:   The name of a database.  Ex:  "main" or "temp" or
+**           the symbolic name assigned to an ATTACH-ed database.
+**
+**      Y:   The name of a table in a FROM clause.  Or in a trigger
+**           one of the special names "old" or "new".
+**
+**      Z:   The name of a column in table Y.
+**
+** The node at the root of the subtree is modified as follows:
+**
+**    Expr.op        Changed to TK_COLUMN
+**    Expr.pTab      Points to the Table object for X.Y
+**    Expr.iColumn   The column index in X.Y.  -1 for the rowid.
+**    Expr.iTable    The VDBE cursor number for X.Y
+**
+**
+** To resolve result-set references, look for expression nodes of the
+** form Z (with no X and Y prefix) where the Z matches the right-hand
+** size of an AS clause in the result-set of a SELECT.  The Z expression
+** is replaced by a copy of the left-hand side of the result-set expression.
+** Table-name and function resolution occurs on the substituted expression
+** tree.  For example, in:
+**
+**      SELECT a+b AS x, c+d AS y FROM t1 ORDER BY x;
+**
+** The "x" term of the order by is replaced by "a+b" to render:
+**
+**      SELECT a+b AS x, c+d AS y FROM t1 ORDER BY a+b;
+**
+** Function calls are checked to make sure that the function is 
+** defined and that the correct number of arguments are specified.
+** If the function is an aggregate function, then the NC_HasAgg flag is
+** set and the opcode is changed from TK_FUNCTION to TK_AGG_FUNCTION.
+** If an expression contains aggregate functions then the EP_Agg
+** property on the expression is set.
+**
+** An error message is left in pParse if anything is amiss.  The number
+** if errors is returned.
+*/
+SQLITE_PRIVATE int sqlite3ResolveExprNames( 
+  NameContext *pNC,       /* Namespace to resolve expressions in. */
+  Expr *pExpr             /* The expression to be analyzed. */
+){
+  u16 savedHasAgg;
+  Walker w;
+
+  if( pExpr==0 ) return 0;
+#if SQLITE_MAX_EXPR_DEPTH>0
+  {
+    Parse *pParse = pNC->pParse;
+    if( sqlite3ExprCheckHeight(pParse, pExpr->nHeight+pNC->pParse->nHeight) ){
+      return 1;
+    }
+    pParse->nHeight += pExpr->nHeight;
+  }
+#endif
+  savedHasAgg = pNC->ncFlags & (NC_HasAgg|NC_MinMaxAgg);
+  pNC->ncFlags &= ~(NC_HasAgg|NC_MinMaxAgg);
+  w.pParse = pNC->pParse;
+  w.xExprCallback = resolveExprStep;
+  w.xSelectCallback = resolveSelectStep;
+  w.xSelectCallback2 = 0;
+  w.walkerDepth = 0;
+  w.eCode = 0;
+  w.u.pNC = pNC;
+  sqlite3WalkExpr(&w, pExpr);
+#if SQLITE_MAX_EXPR_DEPTH>0
+  pNC->pParse->nHeight -= pExpr->nHeight;
+#endif
+  if( pNC->nErr>0 || w.pParse->nErr>0 ){
+    ExprSetProperty(pExpr, EP_Error);
+  }
+  if( pNC->ncFlags & NC_HasAgg ){
+    ExprSetProperty(pExpr, EP_Agg);
+  }
+  pNC->ncFlags |= savedHasAgg;
+  return ExprHasProperty(pExpr, EP_Error);
+}
+
+/*
+** Resolve all names for all expression in an expression list.  This is
+** just like sqlite3ResolveExprNames() except that it works for an expression
+** list rather than a single expression.
+*/
+SQLITE_PRIVATE int sqlite3ResolveExprListNames( 
+  NameContext *pNC,       /* Namespace to resolve expressions in. */
+  ExprList *pList         /* The expression list to be analyzed. */
+){
+  int i;
+  if( pList ){
+    for(i=0; i<pList->nExpr; i++){
+      if( sqlite3ResolveExprNames(pNC, pList->a[i].pExpr) ) return WRC_Abort;
+    }
+  }
+  return WRC_Continue;
+}
+
+/*
+** Resolve all names in all expressions of a SELECT and in all
+** decendents of the SELECT, including compounds off of p->pPrior,
+** subqueries in expressions, and subqueries used as FROM clause
+** terms.
+**
+** See sqlite3ResolveExprNames() for a description of the kinds of
+** transformations that occur.
+**
+** All SELECT statements should have been expanded using
+** sqlite3SelectExpand() prior to invoking this routine.
+*/
+SQLITE_PRIVATE void sqlite3ResolveSelectNames(
+  Parse *pParse,         /* The parser context */
+  Select *p,             /* The SELECT statement being coded. */
+  NameContext *pOuterNC  /* Name context for parent SELECT statement */
+){
+  Walker w;
+
+  assert( p!=0 );
+  memset(&w, 0, sizeof(w));
+  w.xExprCallback = resolveExprStep;
+  w.xSelectCallback = resolveSelectStep;
+  w.pParse = pParse;
+  w.u.pNC = pOuterNC;
+  sqlite3WalkSelect(&w, p);
+}
+
+/*
+** Resolve names in expressions that can only reference a single table:
+**
+**    *   CHECK constraints
+**    *   WHERE clauses on partial indices
+**
+** The Expr.iTable value for Expr.op==TK_COLUMN nodes of the expression
+** is set to -1 and the Expr.iColumn value is set to the column number.
+**
+** Any errors cause an error message to be set in pParse.
+*/
+SQLITE_PRIVATE void sqlite3ResolveSelfReference(
+  Parse *pParse,      /* Parsing context */
+  Table *pTab,        /* The table being referenced */
+  int type,           /* NC_IsCheck or NC_PartIdx or NC_IdxExpr */
+  Expr *pExpr,        /* Expression to resolve.  May be NULL. */
+  ExprList *pList     /* Expression list to resolve.  May be NUL. */
+){
+  SrcList sSrc;                   /* Fake SrcList for pParse->pNewTable */
+  NameContext sNC;                /* Name context for pParse->pNewTable */
+
+  assert( type==NC_IsCheck || type==NC_PartIdx || type==NC_IdxExpr );
+  memset(&sNC, 0, sizeof(sNC));
+  memset(&sSrc, 0, sizeof(sSrc));
+  sSrc.nSrc = 1;
+  sSrc.a[0].zName = pTab->zName;
+  sSrc.a[0].pTab = pTab;
+  sSrc.a[0].iCursor = -1;
+  sNC.pParse = pParse;
+  sNC.pSrcList = &sSrc;
+  sNC.ncFlags = type;
+  if( sqlite3ResolveExprNames(&sNC, pExpr) ) return;
+  if( pList ) sqlite3ResolveExprListNames(&sNC, pList);
+}
+
+/************** End of resolve.c *********************************************/
+/************** Begin file expr.c ********************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains routines used for analyzing expressions and
+** for generating VDBE code that evaluates expressions in SQLite.
+*/
+/* #include "sqliteInt.h" */
+
+/* Forward declarations */
+static void exprCodeBetween(Parse*,Expr*,int,void(*)(Parse*,Expr*,int,int),int);
+static int exprCodeVector(Parse *pParse, Expr *p, int *piToFree);
+
+/*
+** Return the affinity character for a single column of a table.
+*/
+SQLITE_PRIVATE char sqlite3TableColumnAffinity(Table *pTab, int iCol){
+  assert( iCol<pTab->nCol );
+  return iCol>=0 ? pTab->aCol[iCol].affinity : SQLITE_AFF_INTEGER;
+}
+
+/*
+** Return the 'affinity' of the expression pExpr if any.
+**
+** If pExpr is a column, a reference to a column via an 'AS' alias,
+** or a sub-select with a column as the return value, then the 
+** affinity of that column is returned. Otherwise, 0x00 is returned,
+** indicating no affinity for the expression.
+**
+** i.e. the WHERE clause expressions in the following statements all
+** have an affinity:
+**
+** CREATE TABLE t1(a);
+** SELECT * FROM t1 WHERE a;
+** SELECT a AS b FROM t1 WHERE b;
+** SELECT * FROM t1 WHERE (select a from t1);
+*/
+SQLITE_PRIVATE char sqlite3ExprAffinity(Expr *pExpr){
+  int op;
+  pExpr = sqlite3ExprSkipCollate(pExpr);
+  if( pExpr->flags & EP_Generic ) return 0;
+  op = pExpr->op;
+  if( op==TK_SELECT ){
+    assert( pExpr->flags&EP_xIsSelect );
+    return sqlite3ExprAffinity(pExpr->x.pSelect->pEList->a[0].pExpr);
+  }
+  if( op==TK_REGISTER ) op = pExpr->op2;
+#ifndef SQLITE_OMIT_CAST
+  if( op==TK_CAST ){
+    assert( !ExprHasProperty(pExpr, EP_IntValue) );
+    return sqlite3AffinityType(pExpr->u.zToken, 0);
+  }
+#endif
+  if( op==TK_AGG_COLUMN || op==TK_COLUMN ){
+    return sqlite3TableColumnAffinity(pExpr->pTab, pExpr->iColumn);
+  }
+  if( op==TK_SELECT_COLUMN ){
+    assert( pExpr->pLeft->flags&EP_xIsSelect );
+    return sqlite3ExprAffinity(
+        pExpr->pLeft->x.pSelect->pEList->a[pExpr->iColumn].pExpr
+    );
+  }
+  return pExpr->affinity;
+}
+
+/*
+** Set the collating sequence for expression pExpr to be the collating
+** sequence named by pToken.   Return a pointer to a new Expr node that
+** implements the COLLATE operator.
+**
+** If a memory allocation error occurs, that fact is recorded in pParse->db
+** and the pExpr parameter is returned unchanged.
+*/
+SQLITE_PRIVATE Expr *sqlite3ExprAddCollateToken(
+  Parse *pParse,           /* Parsing context */
+  Expr *pExpr,             /* Add the "COLLATE" clause to this expression */
+  const Token *pCollName,  /* Name of collating sequence */
+  int dequote              /* True to dequote pCollName */
+){
+  if( pCollName->n>0 ){
+    Expr *pNew = sqlite3ExprAlloc(pParse->db, TK_COLLATE, pCollName, dequote);
+    if( pNew ){
+      pNew->pLeft = pExpr;
+      pNew->flags |= EP_Collate|EP_Skip;
+      pExpr = pNew;
+    }
+  }
+  return pExpr;
+}
+SQLITE_PRIVATE Expr *sqlite3ExprAddCollateString(Parse *pParse, Expr *pExpr, const char *zC){
+  Token s;
+  assert( zC!=0 );
+  sqlite3TokenInit(&s, (char*)zC);
+  return sqlite3ExprAddCollateToken(pParse, pExpr, &s, 0);
+}
+
+/*
+** Skip over any TK_COLLATE operators and any unlikely()
+** or likelihood() function at the root of an expression.
+*/
+SQLITE_PRIVATE Expr *sqlite3ExprSkipCollate(Expr *pExpr){
+  while( pExpr && ExprHasProperty(pExpr, EP_Skip) ){
+    if( ExprHasProperty(pExpr, EP_Unlikely) ){
+      assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
+      assert( pExpr->x.pList->nExpr>0 );
+      assert( pExpr->op==TK_FUNCTION );
+      pExpr = pExpr->x.pList->a[0].pExpr;
+    }else{
+      assert( pExpr->op==TK_COLLATE );
+      pExpr = pExpr->pLeft;
+    }
+  }   
+  return pExpr;
+}
+
+/*
+** Return the collation sequence for the expression pExpr. If
+** there is no defined collating sequence, return NULL.
+**
+** The collating sequence might be determined by a COLLATE operator
+** or by the presence of a column with a defined collating sequence.
+** COLLATE operators take first precedence.  Left operands take
+** precedence over right operands.
+*/
+SQLITE_PRIVATE CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr){
+  sqlite3 *db = pParse->db;
+  CollSeq *pColl = 0;
+  Expr *p = pExpr;
+  while( p ){
+    int op = p->op;
+    if( p->flags & EP_Generic ) break;
+    if( op==TK_CAST || op==TK_UPLUS ){
+      p = p->pLeft;
+      continue;
+    }
+    if( op==TK_COLLATE || (op==TK_REGISTER && p->op2==TK_COLLATE) ){
+      pColl = sqlite3GetCollSeq(pParse, ENC(db), 0, p->u.zToken);
+      break;
+    }
+    if( (op==TK_AGG_COLUMN || op==TK_COLUMN
+          || op==TK_REGISTER || op==TK_TRIGGER)
+     && p->pTab!=0
+    ){
+      /* op==TK_REGISTER && p->pTab!=0 happens when pExpr was originally
+      ** a TK_COLUMN but was previously evaluated and cached in a register */
+      int j = p->iColumn;
+      if( j>=0 ){
+        const char *zColl = p->pTab->aCol[j].zColl;
+        pColl = sqlite3FindCollSeq(db, ENC(db), zColl, 0);
+      }
+      break;
+    }
+    if( p->flags & EP_Collate ){
+      if( p->pLeft && (p->pLeft->flags & EP_Collate)!=0 ){
+        p = p->pLeft;
+      }else{
+        Expr *pNext  = p->pRight;
+        /* The Expr.x union is never used at the same time as Expr.pRight */
+        assert( p->x.pList==0 || p->pRight==0 );
+        /* p->flags holds EP_Collate and p->pLeft->flags does not.  And
+        ** p->x.pSelect cannot.  So if p->x.pLeft exists, it must hold at
+        ** least one EP_Collate. Thus the following two ALWAYS. */
+        if( p->x.pList!=0 && ALWAYS(!ExprHasProperty(p, EP_xIsSelect)) ){
+          int i;
+          for(i=0; ALWAYS(i<p->x.pList->nExpr); i++){
+            if( ExprHasProperty(p->x.pList->a[i].pExpr, EP_Collate) ){
+              pNext = p->x.pList->a[i].pExpr;
+              break;
+            }
+          }
+        }
+        p = pNext;
+      }
+    }else{
+      break;
+    }
+  }
+  if( sqlite3CheckCollSeq(pParse, pColl) ){ 
+    pColl = 0;
+  }
+  return pColl;
+}
+
+/*
+** pExpr is an operand of a comparison operator.  aff2 is the
+** type affinity of the other operand.  This routine returns the
+** type affinity that should be used for the comparison operator.
+*/
+SQLITE_PRIVATE char sqlite3CompareAffinity(Expr *pExpr, char aff2){
+  char aff1 = sqlite3ExprAffinity(pExpr);
+  if( aff1 && aff2 ){
+    /* Both sides of the comparison are columns. If one has numeric
+    ** affinity, use that. Otherwise use no affinity.
+    */
+    if( sqlite3IsNumericAffinity(aff1) || sqlite3IsNumericAffinity(aff2) ){
+      return SQLITE_AFF_NUMERIC;
+    }else{
+      return SQLITE_AFF_BLOB;
+    }
+  }else if( !aff1 && !aff2 ){
+    /* Neither side of the comparison is a column.  Compare the
+    ** results directly.
+    */
+    return SQLITE_AFF_BLOB;
+  }else{
+    /* One side is a column, the other is not. Use the columns affinity. */
+    assert( aff1==0 || aff2==0 );
+    return (aff1 + aff2);
+  }
+}
+
+/*
+** pExpr is a comparison operator.  Return the type affinity that should
+** be applied to both operands prior to doing the comparison.
+*/
+static char comparisonAffinity(Expr *pExpr){
+  char aff;
+  assert( pExpr->op==TK_EQ || pExpr->op==TK_IN || pExpr->op==TK_LT ||
+          pExpr->op==TK_GT || pExpr->op==TK_GE || pExpr->op==TK_LE ||
+          pExpr->op==TK_NE || pExpr->op==TK_IS || pExpr->op==TK_ISNOT );
+  assert( pExpr->pLeft );
+  aff = sqlite3ExprAffinity(pExpr->pLeft);
+  if( pExpr->pRight ){
+    aff = sqlite3CompareAffinity(pExpr->pRight, aff);
+  }else if( ExprHasProperty(pExpr, EP_xIsSelect) ){
+    aff = sqlite3CompareAffinity(pExpr->x.pSelect->pEList->a[0].pExpr, aff);
+  }else if( NEVER(aff==0) ){
+    aff = SQLITE_AFF_BLOB;
+  }
+  return aff;
+}
+
+/*
+** pExpr is a comparison expression, eg. '=', '<', IN(...) etc.
+** idx_affinity is the affinity of an indexed column. Return true
+** if the index with affinity idx_affinity may be used to implement
+** the comparison in pExpr.
+*/
+SQLITE_PRIVATE int sqlite3IndexAffinityOk(Expr *pExpr, char idx_affinity){
+  char aff = comparisonAffinity(pExpr);
+  switch( aff ){
+    case SQLITE_AFF_BLOB:
+      return 1;
+    case SQLITE_AFF_TEXT:
+      return idx_affinity==SQLITE_AFF_TEXT;
+    default:
+      return sqlite3IsNumericAffinity(idx_affinity);
+  }
+}
+
+/*
+** Return the P5 value that should be used for a binary comparison
+** opcode (OP_Eq, OP_Ge etc.) used to compare pExpr1 and pExpr2.
+*/
+static u8 binaryCompareP5(Expr *pExpr1, Expr *pExpr2, int jumpIfNull){
+  u8 aff = (char)sqlite3ExprAffinity(pExpr2);
+  aff = (u8)sqlite3CompareAffinity(pExpr1, aff) | (u8)jumpIfNull;
+  return aff;
+}
+
+/*
+** Return a pointer to the collation sequence that should be used by
+** a binary comparison operator comparing pLeft and pRight.
+**
+** If the left hand expression has a collating sequence type, then it is
+** used. Otherwise the collation sequence for the right hand expression
+** is used, or the default (BINARY) if neither expression has a collating
+** type.
+**
+** Argument pRight (but not pLeft) may be a null pointer. In this case,
+** it is not considered.
+*/
+SQLITE_PRIVATE CollSeq *sqlite3BinaryCompareCollSeq(
+  Parse *pParse, 
+  Expr *pLeft, 
+  Expr *pRight
+){
+  CollSeq *pColl;
+  assert( pLeft );
+  if( pLeft->flags & EP_Collate ){
+    pColl = sqlite3ExprCollSeq(pParse, pLeft);
+  }else if( pRight && (pRight->flags & EP_Collate)!=0 ){
+    pColl = sqlite3ExprCollSeq(pParse, pRight);
+  }else{
+    pColl = sqlite3ExprCollSeq(pParse, pLeft);
+    if( !pColl ){
+      pColl = sqlite3ExprCollSeq(pParse, pRight);
+    }
+  }
+  return pColl;
+}
+
+/*
+** Generate code for a comparison operator.
+*/
+static int codeCompare(
+  Parse *pParse,    /* The parsing (and code generating) context */
+  Expr *pLeft,      /* The left operand */
+  Expr *pRight,     /* The right operand */
+  int opcode,       /* The comparison opcode */
+  int in1, int in2, /* Register holding operands */
+  int dest,         /* Jump here if true.  */
+  int jumpIfNull    /* If true, jump if either operand is NULL */
+){
+  int p5;
+  int addr;
+  CollSeq *p4;
+
+  p4 = sqlite3BinaryCompareCollSeq(pParse, pLeft, pRight);
+  p5 = binaryCompareP5(pLeft, pRight, jumpIfNull);
+  addr = sqlite3VdbeAddOp4(pParse->pVdbe, opcode, in2, dest, in1,
+                           (void*)p4, P4_COLLSEQ);
+  sqlite3VdbeChangeP5(pParse->pVdbe, (u8)p5);
+  return addr;
+}
+
+/*
+** Return true if expression pExpr is a vector, or false otherwise.
+**
+** A vector is defined as any expression that results in two or more
+** columns of result.  Every TK_VECTOR node is an vector because the
+** parser will not generate a TK_VECTOR with fewer than two entries.
+** But a TK_SELECT might be either a vector or a scalar. It is only
+** considered a vector if it has two or more result columns.
+*/
+SQLITE_PRIVATE int sqlite3ExprIsVector(Expr *pExpr){
+  return sqlite3ExprVectorSize(pExpr)>1;
+}
+
+/*
+** If the expression passed as the only argument is of type TK_VECTOR 
+** return the number of expressions in the vector. Or, if the expression
+** is a sub-select, return the number of columns in the sub-select. For
+** any other type of expression, return 1.
+*/
+SQLITE_PRIVATE int sqlite3ExprVectorSize(Expr *pExpr){
+  u8 op = pExpr->op;
+  if( op==TK_REGISTER ) op = pExpr->op2;
+  if( op==TK_VECTOR ){
+    return pExpr->x.pList->nExpr;
+  }else if( op==TK_SELECT ){
+    return pExpr->x.pSelect->pEList->nExpr;
+  }else{
+    return 1;
+  }
+}
+
+#ifndef SQLITE_OMIT_SUBQUERY
+/*
+** Return a pointer to a subexpression of pVector that is the i-th
+** column of the vector (numbered starting with 0).  The caller must
+** ensure that i is within range.
+**
+** If pVector is really a scalar (and "scalar" here includes subqueries
+** that return a single column!) then return pVector unmodified.
+**
+** pVector retains ownership of the returned subexpression.
+**
+** If the vector is a (SELECT ...) then the expression returned is
+** just the expression for the i-th term of the result set, and may
+** not be ready for evaluation because the table cursor has not yet
+** been positioned.
+*/
+SQLITE_PRIVATE Expr *sqlite3VectorFieldSubexpr(Expr *pVector, int i){
+  assert( i<sqlite3ExprVectorSize(pVector) );
+  if( sqlite3ExprIsVector(pVector) ){
+    assert( pVector->op2==0 || pVector->op==TK_REGISTER );
+    if( pVector->op==TK_SELECT || pVector->op2==TK_SELECT ){
+      return pVector->x.pSelect->pEList->a[i].pExpr;
+    }else{
+      return pVector->x.pList->a[i].pExpr;
+    }
+  }
+  return pVector;
+}
+#endif /* !defined(SQLITE_OMIT_SUBQUERY) */
+
+#ifndef SQLITE_OMIT_SUBQUERY
+/*
+** Compute and return a new Expr object which when passed to
+** sqlite3ExprCode() will generate all necessary code to compute
+** the iField-th column of the vector expression pVector.
+**
+** It is ok for pVector to be a scalar (as long as iField==0).  
+** In that case, this routine works like sqlite3ExprDup().
+**
+** The caller owns the returned Expr object and is responsible for
+** ensuring that the returned value eventually gets freed.
+**
+** The caller retains ownership of pVector.  If pVector is a TK_SELECT,
+** then the returned object will reference pVector and so pVector must remain
+** valid for the life of the returned object.  If pVector is a TK_VECTOR
+** or a scalar expression, then it can be deleted as soon as this routine
+** returns.
+**
+** A trick to cause a TK_SELECT pVector to be deleted together with
+** the returned Expr object is to attach the pVector to the pRight field
+** of the returned TK_SELECT_COLUMN Expr object.
+*/
+SQLITE_PRIVATE Expr *sqlite3ExprForVectorField(
+  Parse *pParse,       /* Parsing context */
+  Expr *pVector,       /* The vector.  List of expressions or a sub-SELECT */
+  int iField           /* Which column of the vector to return */
+){
+  Expr *pRet;
+  if( pVector->op==TK_SELECT ){
+    assert( pVector->flags & EP_xIsSelect );
+    /* The TK_SELECT_COLUMN Expr node:
+    **
+    ** pLeft:           pVector containing TK_SELECT
+    ** pRight:          not used.  But recursively deleted.
+    ** iColumn:         Index of a column in pVector
+    ** pLeft->iTable:   First in an array of register holding result, or 0
+    **                  if the result is not yet computed.
+    **
+    ** sqlite3ExprDelete() specifically skips the recursive delete of
+    ** pLeft on TK_SELECT_COLUMN nodes.  But pRight is followed, so pVector
+    ** can be attached to pRight to cause this node to take ownership of
+    ** pVector.  Typically there will be multiple TK_SELECT_COLUMN nodes
+    ** with the same pLeft pointer to the pVector, but only one of them
+    ** will own the pVector.
+    */
+    pRet = sqlite3PExpr(pParse, TK_SELECT_COLUMN, 0, 0, 0);
+    if( pRet ){
+      pRet->iColumn = iField;
+      pRet->pLeft = pVector;
+    }
+    assert( pRet==0 || pRet->iTable==0 );
+  }else{
+    if( pVector->op==TK_VECTOR ) pVector = pVector->x.pList->a[iField].pExpr;
+    pRet = sqlite3ExprDup(pParse->db, pVector, 0);
+  }
+  return pRet;
+}
+#endif /* !define(SQLITE_OMIT_SUBQUERY) */
+
+/*
+** If expression pExpr is of type TK_SELECT, generate code to evaluate
+** it. Return the register in which the result is stored (or, if the 
+** sub-select returns more than one column, the first in an array
+** of registers in which the result is stored).
+**
+** If pExpr is not a TK_SELECT expression, return 0.
+*/
+static int exprCodeSubselect(Parse *pParse, Expr *pExpr){
+  int reg = 0;
+#ifndef SQLITE_OMIT_SUBQUERY
+  if( pExpr->op==TK_SELECT ){
+    reg = sqlite3CodeSubselect(pParse, pExpr, 0, 0);
+  }
+#endif
+  return reg;
+}
+
+/*
+** Argument pVector points to a vector expression - either a TK_VECTOR
+** or TK_SELECT that returns more than one column. This function returns
+** the register number of a register that contains the value of
+** element iField of the vector.
+**
+** If pVector is a TK_SELECT expression, then code for it must have 
+** already been generated using the exprCodeSubselect() routine. In this
+** case parameter regSelect should be the first in an array of registers
+** containing the results of the sub-select. 
+**
+** If pVector is of type TK_VECTOR, then code for the requested field
+** is generated. In this case (*pRegFree) may be set to the number of
+** a temporary register to be freed by the caller before returning.
+**
+** Before returning, output parameter (*ppExpr) is set to point to the
+** Expr object corresponding to element iElem of the vector.
+*/
+static int exprVectorRegister(
+  Parse *pParse,                  /* Parse context */
+  Expr *pVector,                  /* Vector to extract element from */
+  int iField,                     /* Field to extract from pVector */
+  int regSelect,                  /* First in array of registers */
+  Expr **ppExpr,                  /* OUT: Expression element */
+  int *pRegFree                   /* OUT: Temp register to free */
+){
+  u8 op = pVector->op;
+  assert( op==TK_VECTOR || op==TK_REGISTER || op==TK_SELECT );
+  if( op==TK_REGISTER ){
+    *ppExpr = sqlite3VectorFieldSubexpr(pVector, iField);
+    return pVector->iTable+iField;
+  }
+  if( op==TK_SELECT ){
+    *ppExpr = pVector->x.pSelect->pEList->a[iField].pExpr;
+     return regSelect+iField;
+  }
+  *ppExpr = pVector->x.pList->a[iField].pExpr;
+  return sqlite3ExprCodeTemp(pParse, *ppExpr, pRegFree);
+}
+
+/*
+** Expression pExpr is a comparison between two vector values. Compute
+** the result of the comparison (1, 0, or NULL) and write that
+** result into register dest.
+**
+** The caller must satisfy the following preconditions:
+**
+**    if pExpr->op==TK_IS:      op==TK_EQ and p5==SQLITE_NULLEQ
+**    if pExpr->op==TK_ISNOT:   op==TK_NE and p5==SQLITE_NULLEQ
+**    otherwise:                op==pExpr->op and p5==0
+*/
+static void codeVectorCompare(
+  Parse *pParse,        /* Code generator context */
+  Expr *pExpr,          /* The comparison operation */
+  int dest,             /* Write results into this register */
+  u8 op,                /* Comparison operator */
+  u8 p5                 /* SQLITE_NULLEQ or zero */
+){
+  Vdbe *v = pParse->pVdbe;
+  Expr *pLeft = pExpr->pLeft;
+  Expr *pRight = pExpr->pRight;
+  int nLeft = sqlite3ExprVectorSize(pLeft);
+  int i;
+  int regLeft = 0;
+  int regRight = 0;
+  u8 opx = op;
+  int addrDone = sqlite3VdbeMakeLabel(v);
+
+  assert( nLeft==sqlite3ExprVectorSize(pRight) );
+  assert( pExpr->op==TK_EQ || pExpr->op==TK_NE 
+       || pExpr->op==TK_IS || pExpr->op==TK_ISNOT 
+       || pExpr->op==TK_LT || pExpr->op==TK_GT 
+       || pExpr->op==TK_LE || pExpr->op==TK_GE 
+  );
+  assert( pExpr->op==op || (pExpr->op==TK_IS && op==TK_EQ)
+            || (pExpr->op==TK_ISNOT && op==TK_NE) );
+  assert( p5==0 || pExpr->op!=op );
+  assert( p5==SQLITE_NULLEQ || pExpr->op==op );
+
+  p5 |= SQLITE_STOREP2;
+  if( opx==TK_LE ) opx = TK_LT;
+  if( opx==TK_GE ) opx = TK_GT;
+
+  regLeft = exprCodeSubselect(pParse, pLeft);
+  regRight = exprCodeSubselect(pParse, pRight);
+
+  for(i=0; 1 /*Loop exits by "break"*/; i++){
+    int regFree1 = 0, regFree2 = 0;
+    Expr *pL, *pR; 
+    int r1, r2;
+    assert( i>=0 && i<nLeft );
+    if( i>0 ) sqlite3ExprCachePush(pParse);
+    r1 = exprVectorRegister(pParse, pLeft, i, regLeft, &pL, &regFree1);
+    r2 = exprVectorRegister(pParse, pRight, i, regRight, &pR, &regFree2);
+    codeCompare(pParse, pL, pR, opx, r1, r2, dest, p5);
+    testcase(op==OP_Lt); VdbeCoverageIf(v,op==OP_Lt);
+    testcase(op==OP_Le); VdbeCoverageIf(v,op==OP_Le);
+    testcase(op==OP_Gt); VdbeCoverageIf(v,op==OP_Gt);
+    testcase(op==OP_Ge); VdbeCoverageIf(v,op==OP_Ge);
+    testcase(op==OP_Eq); VdbeCoverageIf(v,op==OP_Eq);
+    testcase(op==OP_Ne); VdbeCoverageIf(v,op==OP_Ne);
+    sqlite3ReleaseTempReg(pParse, regFree1);
+    sqlite3ReleaseTempReg(pParse, regFree2);
+    if( i>0 ) sqlite3ExprCachePop(pParse);
+    if( i==nLeft-1 ){
+      break;
+    }
+    if( opx==TK_EQ ){
+      sqlite3VdbeAddOp2(v, OP_IfNot, dest, addrDone); VdbeCoverage(v);
+      p5 |= SQLITE_KEEPNULL;
+    }else if( opx==TK_NE ){
+      sqlite3VdbeAddOp2(v, OP_If, dest, addrDone); VdbeCoverage(v);
+      p5 |= SQLITE_KEEPNULL;
+    }else{
+      assert( op==TK_LT || op==TK_GT || op==TK_LE || op==TK_GE );
+      sqlite3VdbeAddOp2(v, OP_ElseNotEq, 0, addrDone);
+      VdbeCoverageIf(v, op==TK_LT);
+      VdbeCoverageIf(v, op==TK_GT);
+      VdbeCoverageIf(v, op==TK_LE);
+      VdbeCoverageIf(v, op==TK_GE);
+      if( i==nLeft-2 ) opx = op;
+    }
+  }
+  sqlite3VdbeResolveLabel(v, addrDone);
+}
+
+#if SQLITE_MAX_EXPR_DEPTH>0
+/*
+** Check that argument nHeight is less than or equal to the maximum
+** expression depth allowed. If it is not, leave an error message in
+** pParse.
+*/
+SQLITE_PRIVATE int sqlite3ExprCheckHeight(Parse *pParse, int nHeight){
+  int rc = SQLITE_OK;
+  int mxHeight = pParse->db->aLimit[SQLITE_LIMIT_EXPR_DEPTH];
+  if( nHeight>mxHeight ){
+    sqlite3ErrorMsg(pParse, 
+       "Expression tree is too large (maximum depth %d)", mxHeight
+    );
+    rc = SQLITE_ERROR;
+  }
+  return rc;
+}
+
+/* The following three functions, heightOfExpr(), heightOfExprList()
+** and heightOfSelect(), are used to determine the maximum height
+** of any expression tree referenced by the structure passed as the
+** first argument.
+**
+** If this maximum height is greater than the current value pointed
+** to by pnHeight, the second parameter, then set *pnHeight to that
+** value.
+*/
+static void heightOfExpr(Expr *p, int *pnHeight){
+  if( p ){
+    if( p->nHeight>*pnHeight ){
+      *pnHeight = p->nHeight;
+    }
+  }
+}
+static void heightOfExprList(ExprList *p, int *pnHeight){
+  if( p ){
+    int i;
+    for(i=0; i<p->nExpr; i++){
+      heightOfExpr(p->a[i].pExpr, pnHeight);
+    }
+  }
+}
+static void heightOfSelect(Select *p, int *pnHeight){
+  if( p ){
+    heightOfExpr(p->pWhere, pnHeight);
+    heightOfExpr(p->pHaving, pnHeight);
+    heightOfExpr(p->pLimit, pnHeight);
+    heightOfExpr(p->pOffset, pnHeight);
+    heightOfExprList(p->pEList, pnHeight);
+    heightOfExprList(p->pGroupBy, pnHeight);
+    heightOfExprList(p->pOrderBy, pnHeight);
+    heightOfSelect(p->pPrior, pnHeight);
+  }
+}
+
+/*
+** Set the Expr.nHeight variable in the structure passed as an 
+** argument. An expression with no children, Expr.pList or 
+** Expr.pSelect member has a height of 1. Any other expression
+** has a height equal to the maximum height of any other 
+** referenced Expr plus one.
+**
+** Also propagate EP_Propagate flags up from Expr.x.pList to Expr.flags,
+** if appropriate.
+*/
+static void exprSetHeight(Expr *p){
+  int nHeight = 0;
+  heightOfExpr(p->pLeft, &nHeight);
+  heightOfExpr(p->pRight, &nHeight);
+  if( ExprHasProperty(p, EP_xIsSelect) ){
+    heightOfSelect(p->x.pSelect, &nHeight);
+  }else if( p->x.pList ){
+    heightOfExprList(p->x.pList, &nHeight);
+    p->flags |= EP_Propagate & sqlite3ExprListFlags(p->x.pList);
+  }
+  p->nHeight = nHeight + 1;
+}
+
+/*
+** Set the Expr.nHeight variable using the exprSetHeight() function. If
+** the height is greater than the maximum allowed expression depth,
+** leave an error in pParse.
+**
+** Also propagate all EP_Propagate flags from the Expr.x.pList into
+** Expr.flags. 
+*/
+SQLITE_PRIVATE void sqlite3ExprSetHeightAndFlags(Parse *pParse, Expr *p){
+  if( pParse->nErr ) return;
+  exprSetHeight(p);
+  sqlite3ExprCheckHeight(pParse, p->nHeight);
+}
+
+/*
+** Return the maximum height of any expression tree referenced
+** by the select statement passed as an argument.
+*/
+SQLITE_PRIVATE int sqlite3SelectExprHeight(Select *p){
+  int nHeight = 0;
+  heightOfSelect(p, &nHeight);
+  return nHeight;
+}
+#else /* ABOVE:  Height enforcement enabled.  BELOW: Height enforcement off */
+/*
+** Propagate all EP_Propagate flags from the Expr.x.pList into
+** Expr.flags. 
+*/
+SQLITE_PRIVATE void sqlite3ExprSetHeightAndFlags(Parse *pParse, Expr *p){
+  if( p && p->x.pList && !ExprHasProperty(p, EP_xIsSelect) ){
+    p->flags |= EP_Propagate & sqlite3ExprListFlags(p->x.pList);
+  }
+}
+#define exprSetHeight(y)
+#endif /* SQLITE_MAX_EXPR_DEPTH>0 */
+
+/*
+** This routine is the core allocator for Expr nodes.
+**
+** Construct a new expression node and return a pointer to it.  Memory
+** for this node and for the pToken argument is a single allocation
+** obtained from sqlite3DbMalloc().  The calling function
+** is responsible for making sure the node eventually gets freed.
+**
+** If dequote is true, then the token (if it exists) is dequoted.
+** If dequote is false, no dequoting is performed.  The deQuote
+** parameter is ignored if pToken is NULL or if the token does not
+** appear to be quoted.  If the quotes were of the form "..." (double-quotes)
+** then the EP_DblQuoted flag is set on the expression node.
+**
+** Special case:  If op==TK_INTEGER and pToken points to a string that
+** can be translated into a 32-bit integer, then the token is not
+** stored in u.zToken.  Instead, the integer values is written
+** into u.iValue and the EP_IntValue flag is set.  No extra storage
+** is allocated to hold the integer text and the dequote flag is ignored.
+*/
+SQLITE_PRIVATE Expr *sqlite3ExprAlloc(
+  sqlite3 *db,            /* Handle for sqlite3DbMallocRawNN() */
+  int op,                 /* Expression opcode */
+  const Token *pToken,    /* Token argument.  Might be NULL */
+  int dequote             /* True to dequote */
+){
+  Expr *pNew;
+  int nExtra = 0;
+  int iValue = 0;
+
+  assert( db!=0 );
+  if( pToken ){
+    if( op!=TK_INTEGER || pToken->z==0
+          || sqlite3GetInt32(pToken->z, &iValue)==0 ){
+      nExtra = pToken->n+1;
+      assert( iValue>=0 );
+    }
+  }
+  pNew = sqlite3DbMallocRawNN(db, sizeof(Expr)+nExtra);
+  if( pNew ){
+    memset(pNew, 0, sizeof(Expr));
+    pNew->op = (u8)op;
+    pNew->iAgg = -1;
+    if( pToken ){
+      if( nExtra==0 ){
+        pNew->flags |= EP_IntValue;
+        pNew->u.iValue = iValue;
+      }else{
+        pNew->u.zToken = (char*)&pNew[1];
+        assert( pToken->z!=0 || pToken->n==0 );
+        if( pToken->n ) memcpy(pNew->u.zToken, pToken->z, pToken->n);
+        pNew->u.zToken[pToken->n] = 0;
+        if( dequote && sqlite3Isquote(pNew->u.zToken[0]) ){
+          if( pNew->u.zToken[0]=='"' ) pNew->flags |= EP_DblQuoted;
+          sqlite3Dequote(pNew->u.zToken);
+        }
+      }
+    }
+#if SQLITE_MAX_EXPR_DEPTH>0
+    pNew->nHeight = 1;
+#endif  
+  }
+  return pNew;
+}
+
+/*
+** Allocate a new expression node from a zero-terminated token that has
+** already been dequoted.
+*/
+SQLITE_PRIVATE Expr *sqlite3Expr(
+  sqlite3 *db,            /* Handle for sqlite3DbMallocZero() (may be null) */
+  int op,                 /* Expression opcode */
+  const char *zToken      /* Token argument.  Might be NULL */
+){
+  Token x;
+  x.z = zToken;
+  x.n = zToken ? sqlite3Strlen30(zToken) : 0;
+  return sqlite3ExprAlloc(db, op, &x, 0);
+}
+
+/*
+** Attach subtrees pLeft and pRight to the Expr node pRoot.
+**
+** If pRoot==NULL that means that a memory allocation error has occurred.
+** In that case, delete the subtrees pLeft and pRight.
+*/
+SQLITE_PRIVATE void sqlite3ExprAttachSubtrees(
+  sqlite3 *db,
+  Expr *pRoot,
+  Expr *pLeft,
+  Expr *pRight
+){
+  if( pRoot==0 ){
+    assert( db->mallocFailed );
+    sqlite3ExprDelete(db, pLeft);
+    sqlite3ExprDelete(db, pRight);
+  }else{
+    if( pRight ){
+      pRoot->pRight = pRight;
+      pRoot->flags |= EP_Propagate & pRight->flags;
+    }
+    if( pLeft ){
+      pRoot->pLeft = pLeft;
+      pRoot->flags |= EP_Propagate & pLeft->flags;
+    }
+    exprSetHeight(pRoot);
+  }
+}
+
+/*
+** Allocate an Expr node which joins as many as two subtrees.
+**
+** One or both of the subtrees can be NULL.  Return a pointer to the new
+** Expr node.  Or, if an OOM error occurs, set pParse->db->mallocFailed,
+** free the subtrees and return NULL.
+*/
+SQLITE_PRIVATE Expr *sqlite3PExpr(
+  Parse *pParse,          /* Parsing context */
+  int op,                 /* Expression opcode */
+  Expr *pLeft,            /* Left operand */
+  Expr *pRight,           /* Right operand */
+  const Token *pToken     /* Argument token */
+){
+  Expr *p;
+  if( op==TK_AND && pParse->nErr==0 ){
+    /* Take advantage of short-circuit false optimization for AND */
+    p = sqlite3ExprAnd(pParse->db, pLeft, pRight);
+  }else{
+    p = sqlite3ExprAlloc(pParse->db, op & TKFLG_MASK, pToken, 1);
+    sqlite3ExprAttachSubtrees(pParse->db, p, pLeft, pRight);
+  }
+  if( p ) {
+    sqlite3ExprCheckHeight(pParse, p->nHeight);
+  }
+  return p;
+}
+
+/*
+** Add pSelect to the Expr.x.pSelect field.  Or, if pExpr is NULL (due
+** do a memory allocation failure) then delete the pSelect object.
+*/
+SQLITE_PRIVATE void sqlite3PExprAddSelect(Parse *pParse, Expr *pExpr, Select *pSelect){
+  if( pExpr ){
+    pExpr->x.pSelect = pSelect;
+    ExprSetProperty(pExpr, EP_xIsSelect|EP_Subquery);
+    sqlite3ExprSetHeightAndFlags(pParse, pExpr);
+  }else{
+    assert( pParse->db->mallocFailed );
+    sqlite3SelectDelete(pParse->db, pSelect);
+  }
+}
+
+
+/*
+** If the expression is always either TRUE or FALSE (respectively),
+** then return 1.  If one cannot determine the truth value of the
+** expression at compile-time return 0.
+**
+** This is an optimization.  If is OK to return 0 here even if
+** the expression really is always false or false (a false negative).
+** But it is a bug to return 1 if the expression might have different
+** boolean values in different circumstances (a false positive.)
+**
+** Note that if the expression is part of conditional for a
+** LEFT JOIN, then we cannot determine at compile-time whether or not
+** is it true or false, so always return 0.
+*/
+static int exprAlwaysTrue(Expr *p){
+  int v = 0;
+  if( ExprHasProperty(p, EP_FromJoin) ) return 0;
+  if( !sqlite3ExprIsInteger(p, &v) ) return 0;
+  return v!=0;
+}
+static int exprAlwaysFalse(Expr *p){
+  int v = 0;
+  if( ExprHasProperty(p, EP_FromJoin) ) return 0;
+  if( !sqlite3ExprIsInteger(p, &v) ) return 0;
+  return v==0;
+}
+
+/*
+** Join two expressions using an AND operator.  If either expression is
+** NULL, then just return the other expression.
+**
+** If one side or the other of the AND is known to be false, then instead
+** of returning an AND expression, just return a constant expression with
+** a value of false.
+*/
+SQLITE_PRIVATE Expr *sqlite3ExprAnd(sqlite3 *db, Expr *pLeft, Expr *pRight){
+  if( pLeft==0 ){
+    return pRight;
+  }else if( pRight==0 ){
+    return pLeft;
+  }else if( exprAlwaysFalse(pLeft) || exprAlwaysFalse(pRight) ){
+    sqlite3ExprDelete(db, pLeft);
+    sqlite3ExprDelete(db, pRight);
+    return sqlite3ExprAlloc(db, TK_INTEGER, &sqlite3IntTokens[0], 0);
+  }else{
+    Expr *pNew = sqlite3ExprAlloc(db, TK_AND, 0, 0);
+    sqlite3ExprAttachSubtrees(db, pNew, pLeft, pRight);
+    return pNew;
+  }
+}
+
+/*
+** Construct a new expression node for a function with multiple
+** arguments.
+*/
+SQLITE_PRIVATE Expr *sqlite3ExprFunction(Parse *pParse, ExprList *pList, Token *pToken){
+  Expr *pNew;
+  sqlite3 *db = pParse->db;
+  assert( pToken );
+  pNew = sqlite3ExprAlloc(db, TK_FUNCTION, pToken, 1);
+  if( pNew==0 ){
+    sqlite3ExprListDelete(db, pList); /* Avoid memory leak when malloc fails */
+    return 0;
+  }
+  pNew->x.pList = pList;
+  assert( !ExprHasProperty(pNew, EP_xIsSelect) );
+  sqlite3ExprSetHeightAndFlags(pParse, pNew);
+  return pNew;
+}
+
+/*
+** Assign a variable number to an expression that encodes a wildcard
+** in the original SQL statement.  
+**
+** Wildcards consisting of a single "?" are assigned the next sequential
+** variable number.
+**
+** Wildcards of the form "?nnn" are assigned the number "nnn".  We make
+** sure "nnn" is not too be to avoid a denial of service attack when
+** the SQL statement comes from an external source.
+**
+** Wildcards of the form ":aaa", "@aaa", or "$aaa" are assigned the same number
+** as the previous instance of the same wildcard.  Or if this is the first
+** instance of the wildcard, the next sequential variable number is
+** assigned.
+*/
+SQLITE_PRIVATE void sqlite3ExprAssignVarNumber(Parse *pParse, Expr *pExpr, u32 n){
+  sqlite3 *db = pParse->db;
+  const char *z;
+
+  if( pExpr==0 ) return;
+  assert( !ExprHasProperty(pExpr, EP_IntValue|EP_Reduced|EP_TokenOnly) );
+  z = pExpr->u.zToken;
+  assert( z!=0 );
+  assert( z[0]!=0 );
+  assert( n==sqlite3Strlen30(z) );
+  if( z[1]==0 ){
+    /* Wildcard of the form "?".  Assign the next variable number */
+    assert( z[0]=='?' );
+    pExpr->iColumn = (ynVar)(++pParse->nVar);
+  }else{
+    ynVar x;
+    if( z[0]=='?' ){
+      /* Wildcard of the form "?nnn".  Convert "nnn" to an integer and
+      ** use it as the variable number */
+      i64 i;
+      int bOk = 0==sqlite3Atoi64(&z[1], &i, n-1, SQLITE_UTF8);
+      x = (ynVar)i;
+      testcase( i==0 );
+      testcase( i==1 );
+      testcase( i==db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER]-1 );
+      testcase( i==db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] );
+      if( bOk==0 || i<1 || i>db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] ){
+        sqlite3ErrorMsg(pParse, "variable number must be between ?1 and ?%d",
+            db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER]);
+        return;
+      }
+      if( i>pParse->nVar ){
+        pParse->nVar = (int)i;
+      }
+    }else{
+      /* Wildcards like ":aaa", "$aaa" or "@aaa".  Reuse the same variable
+      ** number as the prior appearance of the same name, or if the name
+      ** has never appeared before, reuse the same variable number
+      */
+      ynVar i;
+      for(i=x=0; i<pParse->nzVar; i++){
+        if( pParse->azVar[i] && strcmp(pParse->azVar[i],z)==0 ){
+          x = (ynVar)i+1;
+          break;
+        }
+      }
+      if( x==0 ) x = (ynVar)(++pParse->nVar);
+    }
+    pExpr->iColumn = x;
+    if( x>pParse->nzVar ){
+      char **a;
+      a = sqlite3DbRealloc(db, pParse->azVar, x*sizeof(a[0]));
+      if( a==0 ){
+        assert( db->mallocFailed ); /* Error reported through mallocFailed */
+        return;
+      }
+      pParse->azVar = a;
+      memset(&a[pParse->nzVar], 0, (x-pParse->nzVar)*sizeof(a[0]));
+      pParse->nzVar = x;
+    }
+    if( pParse->azVar[x-1]==0 ){
+      pParse->azVar[x-1] = sqlite3DbStrNDup(db, z, n);
+    }
+  } 
+  if( pParse->nVar>db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] ){
+    sqlite3ErrorMsg(pParse, "too many SQL variables");
+  }
+}
+
+/*
+** Recursively delete an expression tree.
+*/
+static SQLITE_NOINLINE void sqlite3ExprDeleteNN(sqlite3 *db, Expr *p){
+  assert( p!=0 );
+  /* Sanity check: Assert that the IntValue is non-negative if it exists */
+  assert( !ExprHasProperty(p, EP_IntValue) || p->u.iValue>=0 );
+#ifdef SQLITE_DEBUG
+  if( ExprHasProperty(p, EP_Leaf) && !ExprHasProperty(p, EP_TokenOnly) ){
+    assert( p->pLeft==0 );
+    assert( p->pRight==0 );
+    assert( p->x.pSelect==0 );
+  }
+#endif
+  if( !ExprHasProperty(p, (EP_TokenOnly|EP_Leaf)) ){
+    /* The Expr.x union is never used at the same time as Expr.pRight */
+    assert( p->x.pList==0 || p->pRight==0 );
+    if( p->pLeft && p->op!=TK_SELECT_COLUMN ) sqlite3ExprDeleteNN(db, p->pLeft);
+    sqlite3ExprDelete(db, p->pRight);
+    if( ExprHasProperty(p, EP_xIsSelect) ){
+      sqlite3SelectDelete(db, p->x.pSelect);
+    }else{
+      sqlite3ExprListDelete(db, p->x.pList);
+    }
+  }
+  if( ExprHasProperty(p, EP_MemToken) ) sqlite3DbFree(db, p->u.zToken);
+  if( !ExprHasProperty(p, EP_Static) ){
+    sqlite3DbFree(db, p);
+  }
+}
+SQLITE_PRIVATE void sqlite3ExprDelete(sqlite3 *db, Expr *p){
+  if( p ) sqlite3ExprDeleteNN(db, p);
+}
+
+/*
+** Return the number of bytes allocated for the expression structure 
+** passed as the first argument. This is always one of EXPR_FULLSIZE,
+** EXPR_REDUCEDSIZE or EXPR_TOKENONLYSIZE.
+*/
+static int exprStructSize(Expr *p){
+  if( ExprHasProperty(p, EP_TokenOnly) ) return EXPR_TOKENONLYSIZE;
+  if( ExprHasProperty(p, EP_Reduced) ) return EXPR_REDUCEDSIZE;
+  return EXPR_FULLSIZE;
+}
+
+/*
+** The dupedExpr*Size() routines each return the number of bytes required
+** to store a copy of an expression or expression tree.  They differ in
+** how much of the tree is measured.
+**
+**     dupedExprStructSize()     Size of only the Expr structure 
+**     dupedExprNodeSize()       Size of Expr + space for token
+**     dupedExprSize()           Expr + token + subtree components
+**
+***************************************************************************
+**
+** The dupedExprStructSize() function returns two values OR-ed together:  
+** (1) the space required for a copy of the Expr structure only and 
+** (2) the EP_xxx flags that indicate what the structure size should be.
+** The return values is always one of:
+**
+**      EXPR_FULLSIZE
+**      EXPR_REDUCEDSIZE   | EP_Reduced
+**      EXPR_TOKENONLYSIZE | EP_TokenOnly
+**
+** The size of the structure can be found by masking the return value
+** of this routine with 0xfff.  The flags can be found by masking the
+** return value with EP_Reduced|EP_TokenOnly.
+**
+** Note that with flags==EXPRDUP_REDUCE, this routines works on full-size
+** (unreduced) Expr objects as they or originally constructed by the parser.
+** During expression analysis, extra information is computed and moved into
+** later parts of teh Expr object and that extra information might get chopped
+** off if the expression is reduced.  Note also that it does not work to
+** make an EXPRDUP_REDUCE copy of a reduced expression.  It is only legal
+** to reduce a pristine expression tree from the parser.  The implementation
+** of dupedExprStructSize() contain multiple assert() statements that attempt
+** to enforce this constraint.
+*/
+static int dupedExprStructSize(Expr *p, int flags){
+  int nSize;
+  assert( flags==EXPRDUP_REDUCE || flags==0 ); /* Only one flag value allowed */
+  assert( EXPR_FULLSIZE<=0xfff );
+  assert( (0xfff & (EP_Reduced|EP_TokenOnly))==0 );
+  if( 0==flags ){
+    nSize = EXPR_FULLSIZE;
+  }else{
+    assert( !ExprHasProperty(p, EP_TokenOnly|EP_Reduced) );
+    assert( !ExprHasProperty(p, EP_FromJoin) ); 
+    assert( !ExprHasProperty(p, EP_MemToken) );
+    assert( !ExprHasProperty(p, EP_NoReduce) );
+    if( p->pLeft || p->x.pList ){
+      nSize = EXPR_REDUCEDSIZE | EP_Reduced;
+    }else{
+      assert( p->pRight==0 );
+      nSize = EXPR_TOKENONLYSIZE | EP_TokenOnly;
+    }
+  }
+  return nSize;
+}
+
+/*
+** This function returns the space in bytes required to store the copy 
+** of the Expr structure and a copy of the Expr.u.zToken string (if that
+** string is defined.)
+*/
+static int dupedExprNodeSize(Expr *p, int flags){
+  int nByte = dupedExprStructSize(p, flags) & 0xfff;
+  if( !ExprHasProperty(p, EP_IntValue) && p->u.zToken ){
+    nByte += sqlite3Strlen30(p->u.zToken)+1;
+  }
+  return ROUND8(nByte);
+}
+
+/*
+** Return the number of bytes required to create a duplicate of the 
+** expression passed as the first argument. The second argument is a
+** mask containing EXPRDUP_XXX flags.
+**
+** The value returned includes space to create a copy of the Expr struct
+** itself and the buffer referred to by Expr.u.zToken, if any.
+**
+** If the EXPRDUP_REDUCE flag is set, then the return value includes 
+** space to duplicate all Expr nodes in the tree formed by Expr.pLeft 
+** and Expr.pRight variables (but not for any structures pointed to or 
+** descended from the Expr.x.pList or Expr.x.pSelect variables).
+*/
+static int dupedExprSize(Expr *p, int flags){
+  int nByte = 0;
+  if( p ){
+    nByte = dupedExprNodeSize(p, flags);
+    if( flags&EXPRDUP_REDUCE ){
+      nByte += dupedExprSize(p->pLeft, flags) + dupedExprSize(p->pRight, flags);
+    }
+  }
+  return nByte;
+}
+
+/*
+** This function is similar to sqlite3ExprDup(), except that if pzBuffer 
+** is not NULL then *pzBuffer is assumed to point to a buffer large enough 
+** to store the copy of expression p, the copies of p->u.zToken
+** (if applicable), and the copies of the p->pLeft and p->pRight expressions,
+** if any. Before returning, *pzBuffer is set to the first byte past the
+** portion of the buffer copied into by this function.
+*/
+static Expr *exprDup(sqlite3 *db, Expr *p, int dupFlags, u8 **pzBuffer){
+  Expr *pNew;           /* Value to return */
+  u8 *zAlloc;           /* Memory space from which to build Expr object */
+  u32 staticFlag;       /* EP_Static if space not obtained from malloc */
+
+  assert( db!=0 );
+  assert( p );
+  assert( dupFlags==0 || dupFlags==EXPRDUP_REDUCE );
+  assert( pzBuffer==0 || dupFlags==EXPRDUP_REDUCE );
+
+  /* Figure out where to write the new Expr structure. */
+  if( pzBuffer ){
+    zAlloc = *pzBuffer;
+    staticFlag = EP_Static;
+  }else{
+    zAlloc = sqlite3DbMallocRawNN(db, dupedExprSize(p, dupFlags));
+    staticFlag = 0;
+  }
+  pNew = (Expr *)zAlloc;
+
+  if( pNew ){
+    /* Set nNewSize to the size allocated for the structure pointed to
+    ** by pNew. This is either EXPR_FULLSIZE, EXPR_REDUCEDSIZE or
+    ** EXPR_TOKENONLYSIZE. nToken is set to the number of bytes consumed
+    ** by the copy of the p->u.zToken string (if any).
+    */
+    const unsigned nStructSize = dupedExprStructSize(p, dupFlags);
+    const int nNewSize = nStructSize & 0xfff;
+    int nToken;
+    if( !ExprHasProperty(p, EP_IntValue) && p->u.zToken ){
+      nToken = sqlite3Strlen30(p->u.zToken) + 1;
+    }else{
+      nToken = 0;
+    }
+    if( dupFlags ){
+      assert( ExprHasProperty(p, EP_Reduced)==0 );
+      memcpy(zAlloc, p, nNewSize);
+    }else{
+      u32 nSize = (u32)exprStructSize(p);
+      memcpy(zAlloc, p, nSize);
+      if( nSize<EXPR_FULLSIZE ){ 
+        memset(&zAlloc[nSize], 0, EXPR_FULLSIZE-nSize);
+      }
+    }
+
+    /* Set the EP_Reduced, EP_TokenOnly, and EP_Static flags appropriately. */
+    pNew->flags &= ~(EP_Reduced|EP_TokenOnly|EP_Static|EP_MemToken);
+    pNew->flags |= nStructSize & (EP_Reduced|EP_TokenOnly);
+    pNew->flags |= staticFlag;
+
+    /* Copy the p->u.zToken string, if any. */
+    if( nToken ){
+      char *zToken = pNew->u.zToken = (char*)&zAlloc[nNewSize];
+      memcpy(zToken, p->u.zToken, nToken);
+    }
+
+    if( 0==((p->flags|pNew->flags) & (EP_TokenOnly|EP_Leaf)) ){
+      /* Fill in the pNew->x.pSelect or pNew->x.pList member. */
+      if( ExprHasProperty(p, EP_xIsSelect) ){
+        pNew->x.pSelect = sqlite3SelectDup(db, p->x.pSelect, dupFlags);
+      }else{
+        pNew->x.pList = sqlite3ExprListDup(db, p->x.pList, dupFlags);
+      }
+    }
+
+    /* Fill in pNew->pLeft and pNew->pRight. */
+    if( ExprHasProperty(pNew, EP_Reduced|EP_TokenOnly) ){
+      zAlloc += dupedExprNodeSize(p, dupFlags);
+      if( !ExprHasProperty(pNew, EP_TokenOnly|EP_Leaf) ){
+        pNew->pLeft = p->pLeft ?
+                      exprDup(db, p->pLeft, EXPRDUP_REDUCE, &zAlloc) : 0;
+        pNew->pRight = p->pRight ?
+                       exprDup(db, p->pRight, EXPRDUP_REDUCE, &zAlloc) : 0;
+      }
+      if( pzBuffer ){
+        *pzBuffer = zAlloc;
+      }
+    }else{
+      if( !ExprHasProperty(p, EP_TokenOnly|EP_Leaf) ){
+        if( pNew->op==TK_SELECT_COLUMN ){
+          pNew->pLeft = p->pLeft;
+        }else{
+          pNew->pLeft = sqlite3ExprDup(db, p->pLeft, 0);
+        }
+        pNew->pRight = sqlite3ExprDup(db, p->pRight, 0);
+      }
+    }
+  }
+  return pNew;
+}
+
+/*
+** Create and return a deep copy of the object passed as the second 
+** argument. If an OOM condition is encountered, NULL is returned
+** and the db->mallocFailed flag set.
+*/
+#ifndef SQLITE_OMIT_CTE
+static With *withDup(sqlite3 *db, With *p){
+  With *pRet = 0;
+  if( p ){
+    int nByte = sizeof(*p) + sizeof(p->a[0]) * (p->nCte-1);
+    pRet = sqlite3DbMallocZero(db, nByte);
+    if( pRet ){
+      int i;
+      pRet->nCte = p->nCte;
+      for(i=0; i<p->nCte; i++){
+        pRet->a[i].pSelect = sqlite3SelectDup(db, p->a[i].pSelect, 0);
+        pRet->a[i].pCols = sqlite3ExprListDup(db, p->a[i].pCols, 0);
+        pRet->a[i].zName = sqlite3DbStrDup(db, p->a[i].zName);
+      }
+    }
+  }
+  return pRet;
+}
+#else
+# define withDup(x,y) 0
+#endif
+
+/*
+** The following group of routines make deep copies of expressions,
+** expression lists, ID lists, and select statements.  The copies can
+** be deleted (by being passed to their respective ...Delete() routines)
+** without effecting the originals.
+**
+** The expression list, ID, and source lists return by sqlite3ExprListDup(),
+** sqlite3IdListDup(), and sqlite3SrcListDup() can not be further expanded 
+** by subsequent calls to sqlite*ListAppend() routines.
+**
+** Any tables that the SrcList might point to are not duplicated.
+**
+** The flags parameter contains a combination of the EXPRDUP_XXX flags.
+** If the EXPRDUP_REDUCE flag is set, then the structure returned is a
+** truncated version of the usual Expr structure that will be stored as
+** part of the in-memory representation of the database schema.
+*/
+SQLITE_PRIVATE Expr *sqlite3ExprDup(sqlite3 *db, Expr *p, int flags){
+  assert( flags==0 || flags==EXPRDUP_REDUCE );
+  return p ? exprDup(db, p, flags, 0) : 0;
+}
+SQLITE_PRIVATE ExprList *sqlite3ExprListDup(sqlite3 *db, ExprList *p, int flags){
+  ExprList *pNew;
+  struct ExprList_item *pItem, *pOldItem;
+  int i;
+  assert( db!=0 );
+  if( p==0 ) return 0;
+  pNew = sqlite3DbMallocRawNN(db, sizeof(*pNew) );
+  if( pNew==0 ) return 0;
+  pNew->nExpr = i = p->nExpr;
+  if( (flags & EXPRDUP_REDUCE)==0 ) for(i=1; i<p->nExpr; i+=i){}
+  pNew->a = pItem = sqlite3DbMallocRawNN(db,  i*sizeof(p->a[0]) );
+  if( pItem==0 ){
+    sqlite3DbFree(db, pNew);
+    return 0;
+  } 
+  pOldItem = p->a;
+  for(i=0; i<p->nExpr; i++, pItem++, pOldItem++){
+    Expr *pOldExpr = pOldItem->pExpr;
+    pItem->pExpr = sqlite3ExprDup(db, pOldExpr, flags);
+    pItem->zName = sqlite3DbStrDup(db, pOldItem->zName);
+    pItem->zSpan = sqlite3DbStrDup(db, pOldItem->zSpan);
+    pItem->sortOrder = pOldItem->sortOrder;
+    pItem->done = 0;
+    pItem->bSpanIsTab = pOldItem->bSpanIsTab;
+    pItem->u = pOldItem->u;
+  }
+  return pNew;
+}
+
+/*
+** If cursors, triggers, views and subqueries are all omitted from
+** the build, then none of the following routines, except for 
+** sqlite3SelectDup(), can be called. sqlite3SelectDup() is sometimes
+** called with a NULL argument.
+*/
+#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_TRIGGER) \
+ || !defined(SQLITE_OMIT_SUBQUERY)
+SQLITE_PRIVATE SrcList *sqlite3SrcListDup(sqlite3 *db, SrcList *p, int flags){
+  SrcList *pNew;
+  int i;
+  int nByte;
+  assert( db!=0 );
+  if( p==0 ) return 0;
+  nByte = sizeof(*p) + (p->nSrc>0 ? sizeof(p->a[0]) * (p->nSrc-1) : 0);
+  pNew = sqlite3DbMallocRawNN(db, nByte );
+  if( pNew==0 ) return 0;
+  pNew->nSrc = pNew->nAlloc = p->nSrc;
+  for(i=0; i<p->nSrc; i++){
+    struct SrcList_item *pNewItem = &pNew->a[i];
+    struct SrcList_item *pOldItem = &p->a[i];
+    Table *pTab;
+    pNewItem->pSchema = pOldItem->pSchema;
+    pNewItem->zDatabase = sqlite3DbStrDup(db, pOldItem->zDatabase);
+    pNewItem->zName = sqlite3DbStrDup(db, pOldItem->zName);
+    pNewItem->zAlias = sqlite3DbStrDup(db, pOldItem->zAlias);
+    pNewItem->fg = pOldItem->fg;
+    pNewItem->iCursor = pOldItem->iCursor;
+    pNewItem->addrFillSub = pOldItem->addrFillSub;
+    pNewItem->regReturn = pOldItem->regReturn;
+    if( pNewItem->fg.isIndexedBy ){
+      pNewItem->u1.zIndexedBy = sqlite3DbStrDup(db, pOldItem->u1.zIndexedBy);
+    }
+    pNewItem->pIBIndex = pOldItem->pIBIndex;
+    if( pNewItem->fg.isTabFunc ){
+      pNewItem->u1.pFuncArg = 
+          sqlite3ExprListDup(db, pOldItem->u1.pFuncArg, flags);
+    }
+    pTab = pNewItem->pTab = pOldItem->pTab;
+    if( pTab ){
+      pTab->nRef++;
+    }
+    pNewItem->pSelect = sqlite3SelectDup(db, pOldItem->pSelect, flags);
+    pNewItem->pOn = sqlite3ExprDup(db, pOldItem->pOn, flags);
+    pNewItem->pUsing = sqlite3IdListDup(db, pOldItem->pUsing);
+    pNewItem->colUsed = pOldItem->colUsed;
+  }
+  return pNew;
+}
+SQLITE_PRIVATE IdList *sqlite3IdListDup(sqlite3 *db, IdList *p){
+  IdList *pNew;
+  int i;
+  assert( db!=0 );
+  if( p==0 ) return 0;
+  pNew = sqlite3DbMallocRawNN(db, sizeof(*pNew) );
+  if( pNew==0 ) return 0;
+  pNew->nId = p->nId;
+  pNew->a = sqlite3DbMallocRawNN(db, p->nId*sizeof(p->a[0]) );
+  if( pNew->a==0 ){
+    sqlite3DbFree(db, pNew);
+    return 0;
+  }
+  /* Note that because the size of the allocation for p->a[] is not
+  ** necessarily a power of two, sqlite3IdListAppend() may not be called
+  ** on the duplicate created by this function. */
+  for(i=0; i<p->nId; i++){
+    struct IdList_item *pNewItem = &pNew->a[i];
+    struct IdList_item *pOldItem = &p->a[i];
+    pNewItem->zName = sqlite3DbStrDup(db, pOldItem->zName);
+    pNewItem->idx = pOldItem->idx;
+  }
+  return pNew;
+}
+SQLITE_PRIVATE Select *sqlite3SelectDup(sqlite3 *db, Select *p, int flags){
+  Select *pNew, *pPrior;
+  assert( db!=0 );
+  if( p==0 ) return 0;
+  pNew = sqlite3DbMallocRawNN(db, sizeof(*p) );
+  if( pNew==0 ) return 0;
+  pNew->pEList = sqlite3ExprListDup(db, p->pEList, flags);
+  pNew->pSrc = sqlite3SrcListDup(db, p->pSrc, flags);
+  pNew->pWhere = sqlite3ExprDup(db, p->pWhere, flags);
+  pNew->pGroupBy = sqlite3ExprListDup(db, p->pGroupBy, flags);
+  pNew->pHaving = sqlite3ExprDup(db, p->pHaving, flags);
+  pNew->pOrderBy = sqlite3ExprListDup(db, p->pOrderBy, flags);
+  pNew->op = p->op;
+  pNew->pPrior = pPrior = sqlite3SelectDup(db, p->pPrior, flags);
+  if( pPrior ) pPrior->pNext = pNew;
+  pNew->pNext = 0;
+  pNew->pLimit = sqlite3ExprDup(db, p->pLimit, flags);
+  pNew->pOffset = sqlite3ExprDup(db, p->pOffset, flags);
+  pNew->iLimit = 0;
+  pNew->iOffset = 0;
+  pNew->selFlags = p->selFlags & ~SF_UsesEphemeral;
+  pNew->addrOpenEphm[0] = -1;
+  pNew->addrOpenEphm[1] = -1;
+  pNew->nSelectRow = p->nSelectRow;
+  pNew->pWith = withDup(db, p->pWith);
+  sqlite3SelectSetName(pNew, p->zSelName);
+  return pNew;
+}
+#else
+SQLITE_PRIVATE Select *sqlite3SelectDup(sqlite3 *db, Select *p, int flags){
+  assert( p==0 );
+  return 0;
+}
+#endif
+
+
+/*
+** Add a new element to the end of an expression list.  If pList is
+** initially NULL, then create a new expression list.
+**
+** If a memory allocation error occurs, the entire list is freed and
+** NULL is returned.  If non-NULL is returned, then it is guaranteed
+** that the new entry was successfully appended.
+*/
+SQLITE_PRIVATE ExprList *sqlite3ExprListAppend(
+  Parse *pParse,          /* Parsing context */
+  ExprList *pList,        /* List to which to append. Might be NULL */
+  Expr *pExpr             /* Expression to be appended. Might be NULL */
+){
+  sqlite3 *db = pParse->db;
+  assert( db!=0 );
+  if( pList==0 ){
+    pList = sqlite3DbMallocRawNN(db, sizeof(ExprList) );
+    if( pList==0 ){
+      goto no_mem;
+    }
+    pList->nExpr = 0;
+    pList->a = sqlite3DbMallocRawNN(db, sizeof(pList->a[0]));
+    if( pList->a==0 ) goto no_mem;
+  }else if( (pList->nExpr & (pList->nExpr-1))==0 ){
+    struct ExprList_item *a;
+    assert( pList->nExpr>0 );
+    a = sqlite3DbRealloc(db, pList->a, pList->nExpr*2*sizeof(pList->a[0]));
+    if( a==0 ){
+      goto no_mem;
+    }
+    pList->a = a;
+  }
+  assert( pList->a!=0 );
+  if( 1 ){
+    struct ExprList_item *pItem = &pList->a[pList->nExpr++];
+    memset(pItem, 0, sizeof(*pItem));
+    pItem->pExpr = pExpr;
+  }
+  return pList;
+
+no_mem:     
+  /* Avoid leaking memory if malloc has failed. */
+  sqlite3ExprDelete(db, pExpr);
+  sqlite3ExprListDelete(db, pList);
+  return 0;
+}
+
+/*
+** pColumns and pExpr form a vector assignment which is part of the SET
+** clause of an UPDATE statement.  Like this:
+**
+**        (a,b,c) = (expr1,expr2,expr3)
+** Or:    (a,b,c) = (SELECT x,y,z FROM ....)
+**
+** For each term of the vector assignment, append new entries to the
+** expression list pList.  In the case of a subquery on the LHS, append
+** TK_SELECT_COLUMN expressions.
+*/
+SQLITE_PRIVATE ExprList *sqlite3ExprListAppendVector(
+  Parse *pParse,         /* Parsing context */
+  ExprList *pList,       /* List to which to append. Might be NULL */
+  IdList *pColumns,      /* List of names of LHS of the assignment */
+  Expr *pExpr            /* Vector expression to be appended. Might be NULL */
+){
+  sqlite3 *db = pParse->db;
+  int n;
+  int i;
+  int iFirst = pList ? pList->nExpr : 0;
+  /* pColumns can only be NULL due to an OOM but an OOM will cause an
+  ** exit prior to this routine being invoked */
+  if( NEVER(pColumns==0) ) goto vector_append_error;
+  if( pExpr==0 ) goto vector_append_error;
+  n = sqlite3ExprVectorSize(pExpr);
+  if( pColumns->nId!=n ){
+    sqlite3ErrorMsg(pParse, "%d columns assigned %d values",
+                    pColumns->nId, n);
+    goto vector_append_error;
+  }
+  for(i=0; i<n; i++){
+    Expr *pSubExpr = sqlite3ExprForVectorField(pParse, pExpr, i);
+    pList = sqlite3ExprListAppend(pParse, pList, pSubExpr);
+    if( pList ){
+      assert( pList->nExpr==iFirst+i+1 );
+      pList->a[pList->nExpr-1].zName = pColumns->a[i].zName;
+      pColumns->a[i].zName = 0;
+    }
+  }
+  if( pExpr->op==TK_SELECT ){
+    if( pList && pList->a[iFirst].pExpr ){
+      assert( pList->a[iFirst].pExpr->op==TK_SELECT_COLUMN );
+      pList->a[iFirst].pExpr->pRight = pExpr;
+      pExpr = 0;
+    }
+  }
+
+vector_append_error:
+  sqlite3ExprDelete(db, pExpr);
+  sqlite3IdListDelete(db, pColumns);
+  return pList;
+}
+
+/*
+** Set the sort order for the last element on the given ExprList.
+*/
+SQLITE_PRIVATE void sqlite3ExprListSetSortOrder(ExprList *p, int iSortOrder){
+  if( p==0 ) return;
+  assert( SQLITE_SO_UNDEFINED<0 && SQLITE_SO_ASC>=0 && SQLITE_SO_DESC>0 );
+  assert( p->nExpr>0 );
+  if( iSortOrder<0 ){
+    assert( p->a[p->nExpr-1].sortOrder==SQLITE_SO_ASC );
+    return;
+  }
+  p->a[p->nExpr-1].sortOrder = (u8)iSortOrder;
+}
+
+/*
+** Set the ExprList.a[].zName element of the most recently added item
+** on the expression list.
+**
+** pList might be NULL following an OOM error.  But pName should never be
+** NULL.  If a memory allocation fails, the pParse->db->mallocFailed flag
+** is set.
+*/
+SQLITE_PRIVATE void sqlite3ExprListSetName(
+  Parse *pParse,          /* Parsing context */
+  ExprList *pList,        /* List to which to add the span. */
+  Token *pName,           /* Name to be added */
+  int dequote             /* True to cause the name to be dequoted */
+){
+  assert( pList!=0 || pParse->db->mallocFailed!=0 );
+  if( pList ){
+    struct ExprList_item *pItem;
+    assert( pList->nExpr>0 );
+    pItem = &pList->a[pList->nExpr-1];
+    assert( pItem->zName==0 );
+    pItem->zName = sqlite3DbStrNDup(pParse->db, pName->z, pName->n);
+    if( dequote ) sqlite3Dequote(pItem->zName);
+  }
+}
+
+/*
+** Set the ExprList.a[].zSpan element of the most recently added item
+** on the expression list.
+**
+** pList might be NULL following an OOM error.  But pSpan should never be
+** NULL.  If a memory allocation fails, the pParse->db->mallocFailed flag
+** is set.
+*/
+SQLITE_PRIVATE void sqlite3ExprListSetSpan(
+  Parse *pParse,          /* Parsing context */
+  ExprList *pList,        /* List to which to add the span. */
+  ExprSpan *pSpan         /* The span to be added */
+){
+  sqlite3 *db = pParse->db;
+  assert( pList!=0 || db->mallocFailed!=0 );
+  if( pList ){
+    struct ExprList_item *pItem = &pList->a[pList->nExpr-1];
+    assert( pList->nExpr>0 );
+    assert( db->mallocFailed || pItem->pExpr==pSpan->pExpr );
+    sqlite3DbFree(db, pItem->zSpan);
+    pItem->zSpan = sqlite3DbStrNDup(db, (char*)pSpan->zStart,
+                                    (int)(pSpan->zEnd - pSpan->zStart));
+  }
+}
+
+/*
+** If the expression list pEList contains more than iLimit elements,
+** leave an error message in pParse.
+*/
+SQLITE_PRIVATE void sqlite3ExprListCheckLength(
+  Parse *pParse,
+  ExprList *pEList,
+  const char *zObject
+){
+  int mx = pParse->db->aLimit[SQLITE_LIMIT_COLUMN];
+  testcase( pEList && pEList->nExpr==mx );
+  testcase( pEList && pEList->nExpr==mx+1 );
+  if( pEList && pEList->nExpr>mx ){
+    sqlite3ErrorMsg(pParse, "too many columns in %s", zObject);
+  }
+}
+
+/*
+** Delete an entire expression list.
+*/
+static SQLITE_NOINLINE void exprListDeleteNN(sqlite3 *db, ExprList *pList){
+  int i;
+  struct ExprList_item *pItem;
+  assert( pList->a!=0 || pList->nExpr==0 );
+  for(pItem=pList->a, i=0; i<pList->nExpr; i++, pItem++){
+    sqlite3ExprDelete(db, pItem->pExpr);
+    sqlite3DbFree(db, pItem->zName);
+    sqlite3DbFree(db, pItem->zSpan);
+  }
+  sqlite3DbFree(db, pList->a);
+  sqlite3DbFree(db, pList);
+}
+SQLITE_PRIVATE void sqlite3ExprListDelete(sqlite3 *db, ExprList *pList){
+  if( pList ) exprListDeleteNN(db, pList);
+}
+
+/*
+** Return the bitwise-OR of all Expr.flags fields in the given
+** ExprList.
+*/
+SQLITE_PRIVATE u32 sqlite3ExprListFlags(const ExprList *pList){
+  int i;
+  u32 m = 0;
+  if( pList ){
+    for(i=0; i<pList->nExpr; i++){
+       Expr *pExpr = pList->a[i].pExpr;
+       assert( pExpr!=0 );
+       m |= pExpr->flags;
+    }
+  }
+  return m;
+}
+
+/*
+** These routines are Walker callbacks used to check expressions to
+** see if they are "constant" for some definition of constant.  The
+** Walker.eCode value determines the type of "constant" we are looking
+** for.
+**
+** These callback routines are used to implement the following:
+**
+**     sqlite3ExprIsConstant()                  pWalker->eCode==1
+**     sqlite3ExprIsConstantNotJoin()           pWalker->eCode==2
+**     sqlite3ExprIsTableConstant()             pWalker->eCode==3
+**     sqlite3ExprIsConstantOrFunction()        pWalker->eCode==4 or 5
+**
+** In all cases, the callbacks set Walker.eCode=0 and abort if the expression
+** is found to not be a constant.
+**
+** The sqlite3ExprIsConstantOrFunction() is used for evaluating expressions
+** in a CREATE TABLE statement.  The Walker.eCode value is 5 when parsing
+** an existing schema and 4 when processing a new statement.  A bound
+** parameter raises an error for new statements, but is silently converted
+** to NULL for existing schemas.  This allows sqlite_master tables that 
+** contain a bound parameter because they were generated by older versions
+** of SQLite to be parsed by newer versions of SQLite without raising a
+** malformed schema error.
+*/
+static int exprNodeIsConstant(Walker *pWalker, Expr *pExpr){
+
+  /* If pWalker->eCode is 2 then any term of the expression that comes from
+  ** the ON or USING clauses of a left join disqualifies the expression
+  ** from being considered constant. */
+  if( pWalker->eCode==2 && ExprHasProperty(pExpr, EP_FromJoin) ){
+    pWalker->eCode = 0;
+    return WRC_Abort;
+  }
+
+  switch( pExpr->op ){
+    /* Consider functions to be constant if all their arguments are constant
+    ** and either pWalker->eCode==4 or 5 or the function has the
+    ** SQLITE_FUNC_CONST flag. */
+    case TK_FUNCTION:
+      if( pWalker->eCode>=4 || ExprHasProperty(pExpr,EP_ConstFunc) ){
+        return WRC_Continue;
+      }else{
+        pWalker->eCode = 0;
+        return WRC_Abort;
+      }
+    case TK_ID:
+    case TK_COLUMN:
+    case TK_AGG_FUNCTION:
+    case TK_AGG_COLUMN:
+      testcase( pExpr->op==TK_ID );
+      testcase( pExpr->op==TK_COLUMN );
+      testcase( pExpr->op==TK_AGG_FUNCTION );
+      testcase( pExpr->op==TK_AGG_COLUMN );
+      if( pWalker->eCode==3 && pExpr->iTable==pWalker->u.iCur ){
+        return WRC_Continue;
+      }else{
+        pWalker->eCode = 0;
+        return WRC_Abort;
+      }
+    case TK_VARIABLE:
+      if( pWalker->eCode==5 ){
+        /* Silently convert bound parameters that appear inside of CREATE
+        ** statements into a NULL when parsing the CREATE statement text out
+        ** of the sqlite_master table */
+        pExpr->op = TK_NULL;
+      }else if( pWalker->eCode==4 ){
+        /* A bound parameter in a CREATE statement that originates from
+        ** sqlite3_prepare() causes an error */
+        pWalker->eCode = 0;
+        return WRC_Abort;
+      }
+      /* Fall through */
+    default:
+      testcase( pExpr->op==TK_SELECT ); /* selectNodeIsConstant will disallow */
+      testcase( pExpr->op==TK_EXISTS ); /* selectNodeIsConstant will disallow */
+      return WRC_Continue;
+  }
+}
+static int selectNodeIsConstant(Walker *pWalker, Select *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  pWalker->eCode = 0;
+  return WRC_Abort;
+}
+static int exprIsConst(Expr *p, int initFlag, int iCur){
+  Walker w;
+  memset(&w, 0, sizeof(w));
+  w.eCode = initFlag;
+  w.xExprCallback = exprNodeIsConstant;
+  w.xSelectCallback = selectNodeIsConstant;
+  w.u.iCur = iCur;
+  sqlite3WalkExpr(&w, p);
+  return w.eCode;
+}
+
+/*
+** Walk an expression tree.  Return non-zero if the expression is constant
+** and 0 if it involves variables or function calls.
+**
+** For the purposes of this function, a double-quoted string (ex: "abc")
+** is considered a variable but a single-quoted string (ex: 'abc') is
+** a constant.
+*/
+SQLITE_PRIVATE int sqlite3ExprIsConstant(Expr *p){
+  return exprIsConst(p, 1, 0);
+}
+
+/*
+** Walk an expression tree.  Return non-zero if the expression is constant
+** that does no originate from the ON or USING clauses of a join.
+** Return 0 if it involves variables or function calls or terms from
+** an ON or USING clause.
+*/
+SQLITE_PRIVATE int sqlite3ExprIsConstantNotJoin(Expr *p){
+  return exprIsConst(p, 2, 0);
+}
+
+/*
+** Walk an expression tree.  Return non-zero if the expression is constant
+** for any single row of the table with cursor iCur.  In other words, the
+** expression must not refer to any non-deterministic function nor any
+** table other than iCur.
+*/
+SQLITE_PRIVATE int sqlite3ExprIsTableConstant(Expr *p, int iCur){
+  return exprIsConst(p, 3, iCur);
+}
+
+/*
+** Walk an expression tree.  Return non-zero if the expression is constant
+** or a function call with constant arguments.  Return and 0 if there
+** are any variables.
+**
+** For the purposes of this function, a double-quoted string (ex: "abc")
+** is considered a variable but a single-quoted string (ex: 'abc') is
+** a constant.
+*/
+SQLITE_PRIVATE int sqlite3ExprIsConstantOrFunction(Expr *p, u8 isInit){
+  assert( isInit==0 || isInit==1 );
+  return exprIsConst(p, 4+isInit, 0);
+}
+
+#ifdef SQLITE_ENABLE_CURSOR_HINTS
+/*
+** Walk an expression tree.  Return 1 if the expression contains a
+** subquery of some kind.  Return 0 if there are no subqueries.
+*/
+SQLITE_PRIVATE int sqlite3ExprContainsSubquery(Expr *p){
+  Walker w;
+  memset(&w, 0, sizeof(w));
+  w.eCode = 1;
+  w.xExprCallback = sqlite3ExprWalkNoop;
+  w.xSelectCallback = selectNodeIsConstant;
+  sqlite3WalkExpr(&w, p);
+  return w.eCode==0;
+}
+#endif
+
+/*
+** If the expression p codes a constant integer that is small enough
+** to fit in a 32-bit integer, return 1 and put the value of the integer
+** in *pValue.  If the expression is not an integer or if it is too big
+** to fit in a signed 32-bit integer, return 0 and leave *pValue unchanged.
+*/
+SQLITE_PRIVATE int sqlite3ExprIsInteger(Expr *p, int *pValue){
+  int rc = 0;
+
+  /* If an expression is an integer literal that fits in a signed 32-bit
+  ** integer, then the EP_IntValue flag will have already been set */
+  assert( p->op!=TK_INTEGER || (p->flags & EP_IntValue)!=0
+           || sqlite3GetInt32(p->u.zToken, &rc)==0 );
+
+  if( p->flags & EP_IntValue ){
+    *pValue = p->u.iValue;
+    return 1;
+  }
+  switch( p->op ){
+    case TK_UPLUS: {
+      rc = sqlite3ExprIsInteger(p->pLeft, pValue);
+      break;
+    }
+    case TK_UMINUS: {
+      int v;
+      if( sqlite3ExprIsInteger(p->pLeft, &v) ){
+        assert( v!=(-2147483647-1) );
+        *pValue = -v;
+        rc = 1;
+      }
+      break;
+    }
+    default: break;
+  }
+  return rc;
+}
+
+/*
+** Return FALSE if there is no chance that the expression can be NULL.
+**
+** If the expression might be NULL or if the expression is too complex
+** to tell return TRUE.  
+**
+** This routine is used as an optimization, to skip OP_IsNull opcodes
+** when we know that a value cannot be NULL.  Hence, a false positive
+** (returning TRUE when in fact the expression can never be NULL) might
+** be a small performance hit but is otherwise harmless.  On the other
+** hand, a false negative (returning FALSE when the result could be NULL)
+** will likely result in an incorrect answer.  So when in doubt, return
+** TRUE.
+*/
+SQLITE_PRIVATE int sqlite3ExprCanBeNull(const Expr *p){
+  u8 op;
+  while( p->op==TK_UPLUS || p->op==TK_UMINUS ){ p = p->pLeft; }
+  op = p->op;
+  if( op==TK_REGISTER ) op = p->op2;
+  switch( op ){
+    case TK_INTEGER:
+    case TK_STRING:
+    case TK_FLOAT:
+    case TK_BLOB:
+      return 0;
+    case TK_COLUMN:
+      assert( p->pTab!=0 );
+      return ExprHasProperty(p, EP_CanBeNull) ||
+             (p->iColumn>=0 && p->pTab->aCol[p->iColumn].notNull==0);
+    default:
+      return 1;
+  }
+}
+
+/*
+** Return TRUE if the given expression is a constant which would be
+** unchanged by OP_Affinity with the affinity given in the second
+** argument.
+**
+** This routine is used to determine if the OP_Affinity operation
+** can be omitted.  When in doubt return FALSE.  A false negative
+** is harmless.  A false positive, however, can result in the wrong
+** answer.
+*/
+SQLITE_PRIVATE int sqlite3ExprNeedsNoAffinityChange(const Expr *p, char aff){
+  u8 op;
+  if( aff==SQLITE_AFF_BLOB ) return 1;
+  while( p->op==TK_UPLUS || p->op==TK_UMINUS ){ p = p->pLeft; }
+  op = p->op;
+  if( op==TK_REGISTER ) op = p->op2;
+  switch( op ){
+    case TK_INTEGER: {
+      return aff==SQLITE_AFF_INTEGER || aff==SQLITE_AFF_NUMERIC;
+    }
+    case TK_FLOAT: {
+      return aff==SQLITE_AFF_REAL || aff==SQLITE_AFF_NUMERIC;
+    }
+    case TK_STRING: {
+      return aff==SQLITE_AFF_TEXT;
+    }
+    case TK_BLOB: {
+      return 1;
+    }
+    case TK_COLUMN: {
+      assert( p->iTable>=0 );  /* p cannot be part of a CHECK constraint */
+      return p->iColumn<0
+          && (aff==SQLITE_AFF_INTEGER || aff==SQLITE_AFF_NUMERIC);
+    }
+    default: {
+      return 0;
+    }
+  }
+}
+
+/*
+** Return TRUE if the given string is a row-id column name.
+*/
+SQLITE_PRIVATE int sqlite3IsRowid(const char *z){
+  if( sqlite3StrICmp(z, "_ROWID_")==0 ) return 1;
+  if( sqlite3StrICmp(z, "ROWID")==0 ) return 1;
+  if( sqlite3StrICmp(z, "OID")==0 ) return 1;
+  return 0;
+}
+
+/*
+** pX is the RHS of an IN operator.  If pX is a SELECT statement 
+** that can be simplified to a direct table access, then return
+** a pointer to the SELECT statement.  If pX is not a SELECT statement,
+** or if the SELECT statement needs to be manifested into a transient
+** table, then return NULL.
+*/
+#ifndef SQLITE_OMIT_SUBQUERY
+static Select *isCandidateForInOpt(Expr *pX){
+  Select *p;
+  SrcList *pSrc;
+  ExprList *pEList;
+  Table *pTab;
+  int i;
+  if( !ExprHasProperty(pX, EP_xIsSelect) ) return 0;  /* Not a subquery */
+  if( ExprHasProperty(pX, EP_VarSelect)  ) return 0;  /* Correlated subq */
+  p = pX->x.pSelect;
+  if( p->pPrior ) return 0;              /* Not a compound SELECT */
+  if( p->selFlags & (SF_Distinct|SF_Aggregate) ){
+    testcase( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct );
+    testcase( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Aggregate );
+    return 0; /* No DISTINCT keyword and no aggregate functions */
+  }
+  assert( p->pGroupBy==0 );              /* Has no GROUP BY clause */
+  if( p->pLimit ) return 0;              /* Has no LIMIT clause */
+  assert( p->pOffset==0 );               /* No LIMIT means no OFFSET */
+  if( p->pWhere ) return 0;              /* Has no WHERE clause */
+  pSrc = p->pSrc;
+  assert( pSrc!=0 );
+  if( pSrc->nSrc!=1 ) return 0;          /* Single term in FROM clause */
+  if( pSrc->a[0].pSelect ) return 0;     /* FROM is not a subquery or view */
+  pTab = pSrc->a[0].pTab;
+  assert( pTab!=0 );
+  assert( pTab->pSelect==0 );            /* FROM clause is not a view */
+  if( IsVirtual(pTab) ) return 0;        /* FROM clause not a virtual table */
+  pEList = p->pEList;
+  assert( pEList!=0 );
+  /* All SELECT results must be columns. */
+  for(i=0; i<pEList->nExpr; i++){
+    Expr *pRes = pEList->a[i].pExpr;
+    if( pRes->op!=TK_COLUMN ) return 0;
+    assert( pRes->iTable==pSrc->a[0].iCursor );  /* Not a correlated subquery */
+  }
+  return p;
+}
+#endif /* SQLITE_OMIT_SUBQUERY */
+
+#ifndef SQLITE_OMIT_SUBQUERY
+/*
+** Generate code that checks the left-most column of index table iCur to see if
+** it contains any NULL entries.  Cause the register at regHasNull to be set
+** to a non-NULL value if iCur contains no NULLs.  Cause register regHasNull
+** to be set to NULL if iCur contains one or more NULL values.
+*/
+static void sqlite3SetHasNullFlag(Vdbe *v, int iCur, int regHasNull){
+  int addr1;
+  sqlite3VdbeAddOp2(v, OP_Integer, 0, regHasNull);
+  addr1 = sqlite3VdbeAddOp1(v, OP_Rewind, iCur); VdbeCoverage(v);
+  sqlite3VdbeAddOp3(v, OP_Column, iCur, 0, regHasNull);
+  sqlite3VdbeChangeP5(v, OPFLAG_TYPEOFARG);
+  VdbeComment((v, "first_entry_in(%d)", iCur));
+  sqlite3VdbeJumpHere(v, addr1);
+}
+#endif
+
+
+#ifndef SQLITE_OMIT_SUBQUERY
+/*
+** The argument is an IN operator with a list (not a subquery) on the 
+** right-hand side.  Return TRUE if that list is constant.
+*/
+static int sqlite3InRhsIsConstant(Expr *pIn){
+  Expr *pLHS;
+  int res;
+  assert( !ExprHasProperty(pIn, EP_xIsSelect) );
+  pLHS = pIn->pLeft;
+  pIn->pLeft = 0;
+  res = sqlite3ExprIsConstant(pIn);
+  pIn->pLeft = pLHS;
+  return res;
+}
+#endif
+
+/*
+** This function is used by the implementation of the IN (...) operator.
+** The pX parameter is the expression on the RHS of the IN operator, which
+** might be either a list of expressions or a subquery.
+**
+** The job of this routine is to find or create a b-tree object that can
+** be used either to test for membership in the RHS set or to iterate through
+** all members of the RHS set, skipping duplicates.
+**
+** A cursor is opened on the b-tree object that is the RHS of the IN operator
+** and pX->iTable is set to the index of that cursor.
+**
+** The returned value of this function indicates the b-tree type, as follows:
+**
+**   IN_INDEX_ROWID      - The cursor was opened on a database table.
+**   IN_INDEX_INDEX_ASC  - The cursor was opened on an ascending index.
+**   IN_INDEX_INDEX_DESC - The cursor was opened on a descending index.
+**   IN_INDEX_EPH        - The cursor was opened on a specially created and
+**                         populated epheremal table.
+**   IN_INDEX_NOOP       - No cursor was allocated.  The IN operator must be
+**                         implemented as a sequence of comparisons.
+**
+** An existing b-tree might be used if the RHS expression pX is a simple
+** subquery such as:
+**
+**     SELECT <column1>, <column2>... FROM <table>
+**
+** If the RHS of the IN operator is a list or a more complex subquery, then
+** an ephemeral table might need to be generated from the RHS and then
+** pX->iTable made to point to the ephemeral table instead of an
+** existing table.
+**
+** The inFlags parameter must contain exactly one of the bits
+** IN_INDEX_MEMBERSHIP or IN_INDEX_LOOP.  If inFlags contains
+** IN_INDEX_MEMBERSHIP, then the generated table will be used for a
+** fast membership test.  When the IN_INDEX_LOOP bit is set, the
+** IN index will be used to loop over all values of the RHS of the
+** IN operator.
+**
+** When IN_INDEX_LOOP is used (and the b-tree will be used to iterate
+** through the set members) then the b-tree must not contain duplicates.
+** An epheremal table must be used unless the selected columns are guaranteed
+** to be unique - either because it is an INTEGER PRIMARY KEY or due to
+** a UNIQUE constraint or index.
+**
+** When IN_INDEX_MEMBERSHIP is used (and the b-tree will be used 
+** for fast set membership tests) then an epheremal table must 
+** be used unless <columns> is a single INTEGER PRIMARY KEY column or an 
+** index can be found with the specified <columns> as its left-most.
+**
+** If the IN_INDEX_NOOP_OK and IN_INDEX_MEMBERSHIP are both set and
+** if the RHS of the IN operator is a list (not a subquery) then this
+** routine might decide that creating an ephemeral b-tree for membership
+** testing is too expensive and return IN_INDEX_NOOP.  In that case, the
+** calling routine should implement the IN operator using a sequence
+** of Eq or Ne comparison operations.
+**
+** When the b-tree is being used for membership tests, the calling function
+** might need to know whether or not the RHS side of the IN operator
+** contains a NULL.  If prRhsHasNull is not a NULL pointer and 
+** if there is any chance that the (...) might contain a NULL value at
+** runtime, then a register is allocated and the register number written
+** to *prRhsHasNull. If there is no chance that the (...) contains a
+** NULL value, then *prRhsHasNull is left unchanged.
+**
+** If a register is allocated and its location stored in *prRhsHasNull, then
+** the value in that register will be NULL if the b-tree contains one or more
+** NULL values, and it will be some non-NULL value if the b-tree contains no
+** NULL values.
+**
+** If the aiMap parameter is not NULL, it must point to an array containing
+** one element for each column returned by the SELECT statement on the RHS
+** of the IN(...) operator. The i'th entry of the array is populated with the
+** offset of the index column that matches the i'th column returned by the
+** SELECT. For example, if the expression and selected index are:
+**
+**   (?,?,?) IN (SELECT a, b, c FROM t1)
+**   CREATE INDEX i1 ON t1(b, c, a);
+**
+** then aiMap[] is populated with {2, 0, 1}.
+*/
+#ifndef SQLITE_OMIT_SUBQUERY
+SQLITE_PRIVATE int sqlite3FindInIndex(
+  Parse *pParse,             /* Parsing context */
+  Expr *pX,                  /* The right-hand side (RHS) of the IN operator */
+  u32 inFlags,               /* IN_INDEX_LOOP, _MEMBERSHIP, and/or _NOOP_OK */
+  int *prRhsHasNull,         /* Register holding NULL status.  See notes */
+  int *aiMap                 /* Mapping from Index fields to RHS fields */
+){
+  Select *p;                            /* SELECT to the right of IN operator */
+  int eType = 0;                        /* Type of RHS table. IN_INDEX_* */
+  int iTab = pParse->nTab++;            /* Cursor of the RHS table */
+  int mustBeUnique;                     /* True if RHS must be unique */
+  Vdbe *v = sqlite3GetVdbe(pParse);     /* Virtual machine being coded */
+
+  assert( pX->op==TK_IN );
+  mustBeUnique = (inFlags & IN_INDEX_LOOP)!=0;
+
+  /* If the RHS of this IN(...) operator is a SELECT, and if it matters 
+  ** whether or not the SELECT result contains NULL values, check whether
+  ** or not NULL is actually possible (it may not be, for example, due 
+  ** to NOT NULL constraints in the schema). If no NULL values are possible,
+  ** set prRhsHasNull to 0 before continuing.  */
+  if( prRhsHasNull && (pX->flags & EP_xIsSelect) ){
+    int i;
+    ExprList *pEList = pX->x.pSelect->pEList;
+    for(i=0; i<pEList->nExpr; i++){
+      if( sqlite3ExprCanBeNull(pEList->a[i].pExpr) ) break;
+    }
+    if( i==pEList->nExpr ){
+      prRhsHasNull = 0;
+    }
+  }
+
+  /* Check to see if an existing table or index can be used to
+  ** satisfy the query.  This is preferable to generating a new 
+  ** ephemeral table.  */
+  if( pParse->nErr==0 && (p = isCandidateForInOpt(pX))!=0 ){
+    sqlite3 *db = pParse->db;              /* Database connection */
+    Table *pTab;                           /* Table <table>. */
+    i16 iDb;                               /* Database idx for pTab */
+    ExprList *pEList = p->pEList;
+    int nExpr = pEList->nExpr;
+
+    assert( p->pEList!=0 );             /* Because of isCandidateForInOpt(p) */
+    assert( p->pEList->a[0].pExpr!=0 ); /* Because of isCandidateForInOpt(p) */
+    assert( p->pSrc!=0 );               /* Because of isCandidateForInOpt(p) */
+    pTab = p->pSrc->a[0].pTab;
+
+    /* Code an OP_Transaction and OP_TableLock for <table>. */
+    iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+    sqlite3CodeVerifySchema(pParse, iDb);
+    sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
+
+    assert(v);  /* sqlite3GetVdbe() has always been previously called */
+    if( nExpr==1 && pEList->a[0].pExpr->iColumn<0 ){
+      /* The "x IN (SELECT rowid FROM table)" case */
+      int iAddr = sqlite3VdbeAddOp0(v, OP_Once);
+      VdbeCoverage(v);
+
+      sqlite3OpenTable(pParse, iTab, iDb, pTab, OP_OpenRead);
+      eType = IN_INDEX_ROWID;
+
+      sqlite3VdbeJumpHere(v, iAddr);
+    }else{
+      Index *pIdx;                         /* Iterator variable */
+      int affinity_ok = 1;
+      int i;
+
+      /* Check that the affinity that will be used to perform each 
+      ** comparison is the same as the affinity of each column in table
+      ** on the RHS of the IN operator.  If it not, it is not possible to
+      ** use any index of the RHS table.  */
+      for(i=0; i<nExpr && affinity_ok; i++){
+        Expr *pLhs = sqlite3VectorFieldSubexpr(pX->pLeft, i);
+        int iCol = pEList->a[i].pExpr->iColumn;
+        char idxaff = sqlite3TableColumnAffinity(pTab,iCol); /* RHS table */
+        char cmpaff = sqlite3CompareAffinity(pLhs, idxaff);
+        testcase( cmpaff==SQLITE_AFF_BLOB );
+        testcase( cmpaff==SQLITE_AFF_TEXT );
+        switch( cmpaff ){
+          case SQLITE_AFF_BLOB:
+            break;
+          case SQLITE_AFF_TEXT:
+            /* sqlite3CompareAffinity() only returns TEXT if one side or the
+            ** other has no affinity and the other side is TEXT.  Hence,
+            ** the only way for cmpaff to be TEXT is for idxaff to be TEXT
+            ** and for the term on the LHS of the IN to have no affinity. */
+            assert( idxaff==SQLITE_AFF_TEXT );
+            break;
+          default:
+            affinity_ok = sqlite3IsNumericAffinity(idxaff);
+        }
+      }
+
+      if( affinity_ok ){
+        /* Search for an existing index that will work for this IN operator */
+        for(pIdx=pTab->pIndex; pIdx && eType==0; pIdx=pIdx->pNext){
+          Bitmask colUsed;      /* Columns of the index used */
+          Bitmask mCol;         /* Mask for the current column */
+          if( pIdx->nColumn<nExpr ) continue;
+          /* Maximum nColumn is BMS-2, not BMS-1, so that we can compute
+          ** BITMASK(nExpr) without overflowing */
+          testcase( pIdx->nColumn==BMS-2 );
+          testcase( pIdx->nColumn==BMS-1 );
+          if( pIdx->nColumn>=BMS-1 ) continue;
+          if( mustBeUnique ){
+            if( pIdx->nKeyCol>nExpr
+             ||(pIdx->nColumn>nExpr && !IsUniqueIndex(pIdx))
+            ){
+              continue;  /* This index is not unique over the IN RHS columns */
+            }
+          }
+  
+          colUsed = 0;   /* Columns of index used so far */
+          for(i=0; i<nExpr; i++){
+            Expr *pLhs = sqlite3VectorFieldSubexpr(pX->pLeft, i);
+            Expr *pRhs = pEList->a[i].pExpr;
+            CollSeq *pReq = sqlite3BinaryCompareCollSeq(pParse, pLhs, pRhs);
+            int j;
+  
+            assert( pReq!=0 || pRhs->iColumn==XN_ROWID || pParse->nErr );
+            for(j=0; j<nExpr; j++){
+              if( pIdx->aiColumn[j]!=pRhs->iColumn ) continue;
+              assert( pIdx->azColl[j] );
+              if( pReq!=0 && sqlite3StrICmp(pReq->zName, pIdx->azColl[j])!=0 ){
+                continue;
+              }
+              break;
+            }
+            if( j==nExpr ) break;
+            mCol = MASKBIT(j);
+            if( mCol & colUsed ) break; /* Each column used only once */
+            colUsed |= mCol;
+            if( aiMap ) aiMap[i] = j;
+          }
+  
+          assert( i==nExpr || colUsed!=(MASKBIT(nExpr)-1) );
+          if( colUsed==(MASKBIT(nExpr)-1) ){
+            /* If we reach this point, that means the index pIdx is usable */
+            int iAddr = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
+#ifndef SQLITE_OMIT_EXPLAIN
+            sqlite3VdbeAddOp4(v, OP_Explain, 0, 0, 0,
+              sqlite3MPrintf(db, "USING INDEX %s FOR IN-OPERATOR",pIdx->zName),
+              P4_DYNAMIC);
+#endif
+            sqlite3VdbeAddOp3(v, OP_OpenRead, iTab, pIdx->tnum, iDb);
+            sqlite3VdbeSetP4KeyInfo(pParse, pIdx);
+            VdbeComment((v, "%s", pIdx->zName));
+            assert( IN_INDEX_INDEX_DESC == IN_INDEX_INDEX_ASC+1 );
+            eType = IN_INDEX_INDEX_ASC + pIdx->aSortOrder[0];
+  
+            if( prRhsHasNull ){
+#ifdef SQLITE_ENABLE_COLUMN_USED_MASK
+              i64 mask = (1<<nExpr)-1;
+              sqlite3VdbeAddOp4Dup8(v, OP_ColumnsUsed, 
+                  iTab, 0, 0, (u8*)&mask, P4_INT64);
+#endif
+              *prRhsHasNull = ++pParse->nMem;
+              if( nExpr==1 ){
+                sqlite3SetHasNullFlag(v, iTab, *prRhsHasNull);
+              }
+            }
+            sqlite3VdbeJumpHere(v, iAddr);
+          }
+        } /* End loop over indexes */
+      } /* End if( affinity_ok ) */
+    } /* End if not an rowid index */
+  } /* End attempt to optimize using an index */
+
+  /* If no preexisting index is available for the IN clause
+  ** and IN_INDEX_NOOP is an allowed reply
+  ** and the RHS of the IN operator is a list, not a subquery
+  ** and the RHS is not constant or has two or fewer terms,
+  ** then it is not worth creating an ephemeral table to evaluate
+  ** the IN operator so return IN_INDEX_NOOP.
+  */
+  if( eType==0
+   && (inFlags & IN_INDEX_NOOP_OK)
+   && !ExprHasProperty(pX, EP_xIsSelect)
+   && (!sqlite3InRhsIsConstant(pX) || pX->x.pList->nExpr<=2)
+  ){
+    eType = IN_INDEX_NOOP;
+  }
+
+  if( eType==0 ){
+    /* Could not find an existing table or index to use as the RHS b-tree.
+    ** We will have to generate an ephemeral table to do the job.
+    */
+    u32 savedNQueryLoop = pParse->nQueryLoop;
+    int rMayHaveNull = 0;
+    eType = IN_INDEX_EPH;
+    if( inFlags & IN_INDEX_LOOP ){
+      pParse->nQueryLoop = 0;
+      if( pX->pLeft->iColumn<0 && !ExprHasProperty(pX, EP_xIsSelect) ){
+        eType = IN_INDEX_ROWID;
+      }
+    }else if( prRhsHasNull ){
+      *prRhsHasNull = rMayHaveNull = ++pParse->nMem;
+    }
+    sqlite3CodeSubselect(pParse, pX, rMayHaveNull, eType==IN_INDEX_ROWID);
+    pParse->nQueryLoop = savedNQueryLoop;
+  }else{
+    pX->iTable = iTab;
+  }
+
+  if( aiMap && eType!=IN_INDEX_INDEX_ASC && eType!=IN_INDEX_INDEX_DESC ){
+    int i, n;
+    n = sqlite3ExprVectorSize(pX->pLeft);
+    for(i=0; i<n; i++) aiMap[i] = i;
+  }
+  return eType;
+}
+#endif
+
+#ifndef SQLITE_OMIT_SUBQUERY
+/*
+** Argument pExpr is an (?, ?...) IN(...) expression. This 
+** function allocates and returns a nul-terminated string containing 
+** the affinities to be used for each column of the comparison.
+**
+** It is the responsibility of the caller to ensure that the returned
+** string is eventually freed using sqlite3DbFree().
+*/
+static char *exprINAffinity(Parse *pParse, Expr *pExpr){
+  Expr *pLeft = pExpr->pLeft;
+  int nVal = sqlite3ExprVectorSize(pLeft);
+  Select *pSelect = (pExpr->flags & EP_xIsSelect) ? pExpr->x.pSelect : 0;
+  char *zRet;
+
+  assert( pExpr->op==TK_IN );
+  zRet = sqlite3DbMallocZero(pParse->db, nVal+1);
+  if( zRet ){
+    int i;
+    for(i=0; i<nVal; i++){
+      Expr *pA = sqlite3VectorFieldSubexpr(pLeft, i);
+      char a = sqlite3ExprAffinity(pA);
+      if( pSelect ){
+        zRet[i] = sqlite3CompareAffinity(pSelect->pEList->a[i].pExpr, a);
+      }else{
+        zRet[i] = a;
+      }
+    }
+    zRet[nVal] = '\0';
+  }
+  return zRet;
+}
+#endif
+
+#ifndef SQLITE_OMIT_SUBQUERY
+/*
+** Load the Parse object passed as the first argument with an error 
+** message of the form:
+**
+**   "sub-select returns N columns - expected M"
+*/   
+SQLITE_PRIVATE void sqlite3SubselectError(Parse *pParse, int nActual, int nExpect){
+  const char *zFmt = "sub-select returns %d columns - expected %d";
+  sqlite3ErrorMsg(pParse, zFmt, nActual, nExpect);
+}
+#endif
+
+/*
+** Generate code for scalar subqueries used as a subquery expression, EXISTS,
+** or IN operators.  Examples:
+**
+**     (SELECT a FROM b)          -- subquery
+**     EXISTS (SELECT a FROM b)   -- EXISTS subquery
+**     x IN (4,5,11)              -- IN operator with list on right-hand side
+**     x IN (SELECT a FROM b)     -- IN operator with subquery on the right
+**
+** The pExpr parameter describes the expression that contains the IN
+** operator or subquery.
+**
+** If parameter isRowid is non-zero, then expression pExpr is guaranteed
+** to be of the form "<rowid> IN (?, ?, ?)", where <rowid> is a reference
+** to some integer key column of a table B-Tree. In this case, use an
+** intkey B-Tree to store the set of IN(...) values instead of the usual
+** (slower) variable length keys B-Tree.
+**
+** If rMayHaveNull is non-zero, that means that the operation is an IN
+** (not a SELECT or EXISTS) and that the RHS might contains NULLs.
+** All this routine does is initialize the register given by rMayHaveNull
+** to NULL.  Calling routines will take care of changing this register
+** value to non-NULL if the RHS is NULL-free.
+**
+** For a SELECT or EXISTS operator, return the register that holds the
+** result.  For a multi-column SELECT, the result is stored in a contiguous
+** array of registers and the return value is the register of the left-most
+** result column.  Return 0 for IN operators or if an error occurs.
+*/
+#ifndef SQLITE_OMIT_SUBQUERY
+SQLITE_PRIVATE int sqlite3CodeSubselect(
+  Parse *pParse,          /* Parsing context */
+  Expr *pExpr,            /* The IN, SELECT, or EXISTS operator */
+  int rHasNullFlag,       /* Register that records whether NULLs exist in RHS */
+  int isRowid             /* If true, LHS of IN operator is a rowid */
+){
+  int jmpIfDynamic = -1;                      /* One-time test address */
+  int rReg = 0;                           /* Register storing resulting */
+  Vdbe *v = sqlite3GetVdbe(pParse);
+  if( NEVER(v==0) ) return 0;
+  sqlite3ExprCachePush(pParse);
+
+  /* The evaluation of the IN/EXISTS/SELECT must be repeated every time it
+  ** is encountered if any of the following is true:
+  **
+  **    *  The right-hand side is a correlated subquery
+  **    *  The right-hand side is an expression list containing variables
+  **    *  We are inside a trigger
+  **
+  ** If all of the above are false, then we can run this code just once
+  ** save the results, and reuse the same result on subsequent invocations.
+  */
+  if( !ExprHasProperty(pExpr, EP_VarSelect) ){
+    jmpIfDynamic = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
+  }
+
+#ifndef SQLITE_OMIT_EXPLAIN
+  if( pParse->explain==2 ){
+    char *zMsg = sqlite3MPrintf(pParse->db, "EXECUTE %s%s SUBQUERY %d",
+        jmpIfDynamic>=0?"":"CORRELATED ",
+        pExpr->op==TK_IN?"LIST":"SCALAR",
+        pParse->iNextSelectId
+    );
+    sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC);
+  }
+#endif
+
+  switch( pExpr->op ){
+    case TK_IN: {
+      int addr;                   /* Address of OP_OpenEphemeral instruction */
+      Expr *pLeft = pExpr->pLeft; /* the LHS of the IN operator */
+      KeyInfo *pKeyInfo = 0;      /* Key information */
+      int nVal;                   /* Size of vector pLeft */
+      
+      nVal = sqlite3ExprVectorSize(pLeft);
+      assert( !isRowid || nVal==1 );
+
+      /* Whether this is an 'x IN(SELECT...)' or an 'x IN(<exprlist>)'
+      ** expression it is handled the same way.  An ephemeral table is 
+      ** filled with index keys representing the results from the 
+      ** SELECT or the <exprlist>.
+      **
+      ** If the 'x' expression is a column value, or the SELECT...
+      ** statement returns a column value, then the affinity of that
+      ** column is used to build the index keys. If both 'x' and the
+      ** SELECT... statement are columns, then numeric affinity is used
+      ** if either column has NUMERIC or INTEGER affinity. If neither
+      ** 'x' nor the SELECT... statement are columns, then numeric affinity
+      ** is used.
+      */
+      pExpr->iTable = pParse->nTab++;
+      addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, 
+          pExpr->iTable, (isRowid?0:nVal));
+      pKeyInfo = isRowid ? 0 : sqlite3KeyInfoAlloc(pParse->db, nVal, 1);
+
+      if( ExprHasProperty(pExpr, EP_xIsSelect) ){
+        /* Case 1:     expr IN (SELECT ...)
+        **
+        ** Generate code to write the results of the select into the temporary
+        ** table allocated and opened above.
+        */
+        Select *pSelect = pExpr->x.pSelect;
+        ExprList *pEList = pSelect->pEList;
+
+        assert( !isRowid );
+        /* If the LHS and RHS of the IN operator do not match, that
+        ** error will have been caught long before we reach this point. */
+        if( ALWAYS(pEList->nExpr==nVal) ){
+          SelectDest dest;
+          int i;
+          sqlite3SelectDestInit(&dest, SRT_Set, pExpr->iTable);
+          dest.zAffSdst = exprINAffinity(pParse, pExpr);
+          assert( (pExpr->iTable&0x0000FFFF)==pExpr->iTable );
+          pSelect->iLimit = 0;
+          testcase( pSelect->selFlags & SF_Distinct );
+          testcase( pKeyInfo==0 ); /* Caused by OOM in sqlite3KeyInfoAlloc() */
+          if( sqlite3Select(pParse, pSelect, &dest) ){
+            sqlite3DbFree(pParse->db, dest.zAffSdst);
+            sqlite3KeyInfoUnref(pKeyInfo);
+            return 0;
+          }
+          sqlite3DbFree(pParse->db, dest.zAffSdst);
+          assert( pKeyInfo!=0 ); /* OOM will cause exit after sqlite3Select() */
+          assert( pEList!=0 );
+          assert( pEList->nExpr>0 );
+          assert( sqlite3KeyInfoIsWriteable(pKeyInfo) );
+          for(i=0; i<nVal; i++){
+            Expr *p = sqlite3VectorFieldSubexpr(pLeft, i);
+            pKeyInfo->aColl[i] = sqlite3BinaryCompareCollSeq(
+                pParse, p, pEList->a[i].pExpr
+            );
+          }
+        }
+      }else if( ALWAYS(pExpr->x.pList!=0) ){
+        /* Case 2:     expr IN (exprlist)
+        **
+        ** For each expression, build an index key from the evaluation and
+        ** store it in the temporary table. If <expr> is a column, then use
+        ** that columns affinity when building index keys. If <expr> is not
+        ** a column, use numeric affinity.
+        */
+        char affinity;            /* Affinity of the LHS of the IN */
+        int i;
+        ExprList *pList = pExpr->x.pList;
+        struct ExprList_item *pItem;
+        int r1, r2, r3;
+
+        affinity = sqlite3ExprAffinity(pLeft);
+        if( !affinity ){
+          affinity = SQLITE_AFF_BLOB;
+        }
+        if( pKeyInfo ){
+          assert( sqlite3KeyInfoIsWriteable(pKeyInfo) );
+          pKeyInfo->aColl[0] = sqlite3ExprCollSeq(pParse, pExpr->pLeft);
+        }
+
+        /* Loop through each expression in <exprlist>. */
+        r1 = sqlite3GetTempReg(pParse);
+        r2 = sqlite3GetTempReg(pParse);
+        if( isRowid ) sqlite3VdbeAddOp2(v, OP_Null, 0, r2);
+        for(i=pList->nExpr, pItem=pList->a; i>0; i--, pItem++){
+          Expr *pE2 = pItem->pExpr;
+          int iValToIns;
+
+          /* If the expression is not constant then we will need to
+          ** disable the test that was generated above that makes sure
+          ** this code only executes once.  Because for a non-constant
+          ** expression we need to rerun this code each time.
+          */
+          if( jmpIfDynamic>=0 && !sqlite3ExprIsConstant(pE2) ){
+            sqlite3VdbeChangeToNoop(v, jmpIfDynamic);
+            jmpIfDynamic = -1;
+          }
+
+          /* Evaluate the expression and insert it into the temp table */
+          if( isRowid && sqlite3ExprIsInteger(pE2, &iValToIns) ){
+            sqlite3VdbeAddOp3(v, OP_InsertInt, pExpr->iTable, r2, iValToIns);
+          }else{
+            r3 = sqlite3ExprCodeTarget(pParse, pE2, r1);
+            if( isRowid ){
+              sqlite3VdbeAddOp2(v, OP_MustBeInt, r3,
+                                sqlite3VdbeCurrentAddr(v)+2);
+              VdbeCoverage(v);
+              sqlite3VdbeAddOp3(v, OP_Insert, pExpr->iTable, r2, r3);
+            }else{
+              sqlite3VdbeAddOp4(v, OP_MakeRecord, r3, 1, r2, &affinity, 1);
+              sqlite3ExprCacheAffinityChange(pParse, r3, 1);
+              sqlite3VdbeAddOp2(v, OP_IdxInsert, pExpr->iTable, r2);
+            }
+          }
+        }
+        sqlite3ReleaseTempReg(pParse, r1);
+        sqlite3ReleaseTempReg(pParse, r2);
+      }
+      if( pKeyInfo ){
+        sqlite3VdbeChangeP4(v, addr, (void *)pKeyInfo, P4_KEYINFO);
+      }
+      break;
+    }
+
+    case TK_EXISTS:
+    case TK_SELECT:
+    default: {
+      /* Case 3:    (SELECT ... FROM ...)
+      **     or:    EXISTS(SELECT ... FROM ...)
+      **
+      ** For a SELECT, generate code to put the values for all columns of
+      ** the first row into an array of registers and return the index of
+      ** the first register.
+      **
+      ** If this is an EXISTS, write an integer 0 (not exists) or 1 (exists)
+      ** into a register and return that register number.
+      **
+      ** In both cases, the query is augmented with "LIMIT 1".  Any 
+      ** preexisting limit is discarded in place of the new LIMIT 1.
+      */
+      Select *pSel;                         /* SELECT statement to encode */
+      SelectDest dest;                      /* How to deal with SELECT result */
+      int nReg;                             /* Registers to allocate */
+
+      testcase( pExpr->op==TK_EXISTS );
+      testcase( pExpr->op==TK_SELECT );
+      assert( pExpr->op==TK_EXISTS || pExpr->op==TK_SELECT );
+      assert( ExprHasProperty(pExpr, EP_xIsSelect) );
+
+      pSel = pExpr->x.pSelect;
+      nReg = pExpr->op==TK_SELECT ? pSel->pEList->nExpr : 1;
+      sqlite3SelectDestInit(&dest, 0, pParse->nMem+1);
+      pParse->nMem += nReg;
+      if( pExpr->op==TK_SELECT ){
+        dest.eDest = SRT_Mem;
+        dest.iSdst = dest.iSDParm;
+        dest.nSdst = nReg;
+        sqlite3VdbeAddOp3(v, OP_Null, 0, dest.iSDParm, dest.iSDParm+nReg-1);
+        VdbeComment((v, "Init subquery result"));
+      }else{
+        dest.eDest = SRT_Exists;
+        sqlite3VdbeAddOp2(v, OP_Integer, 0, dest.iSDParm);
+        VdbeComment((v, "Init EXISTS result"));
+      }
+      sqlite3ExprDelete(pParse->db, pSel->pLimit);
+      pSel->pLimit = sqlite3ExprAlloc(pParse->db, TK_INTEGER,
+                                  &sqlite3IntTokens[1], 0);
+      pSel->iLimit = 0;
+      pSel->selFlags &= ~SF_MultiValue;
+      if( sqlite3Select(pParse, pSel, &dest) ){
+        return 0;
+      }
+      rReg = dest.iSDParm;
+      ExprSetVVAProperty(pExpr, EP_NoReduce);
+      break;
+    }
+  }
+
+  if( rHasNullFlag ){
+    sqlite3SetHasNullFlag(v, pExpr->iTable, rHasNullFlag);
+  }
+
+  if( jmpIfDynamic>=0 ){
+    sqlite3VdbeJumpHere(v, jmpIfDynamic);
+  }
+  sqlite3ExprCachePop(pParse);
+
+  return rReg;
+}
+#endif /* SQLITE_OMIT_SUBQUERY */
+
+#ifndef SQLITE_OMIT_SUBQUERY
+/*
+** Expr pIn is an IN(...) expression. This function checks that the 
+** sub-select on the RHS of the IN() operator has the same number of 
+** columns as the vector on the LHS. Or, if the RHS of the IN() is not 
+** a sub-query, that the LHS is a vector of size 1.
+*/
+SQLITE_PRIVATE int sqlite3ExprCheckIN(Parse *pParse, Expr *pIn){
+  int nVector = sqlite3ExprVectorSize(pIn->pLeft);
+  if( (pIn->flags & EP_xIsSelect) ){
+    if( nVector!=pIn->x.pSelect->pEList->nExpr ){
+      sqlite3SubselectError(pParse, pIn->x.pSelect->pEList->nExpr, nVector);
+      return 1;
+    }
+  }else if( nVector!=1 ){
+    if( (pIn->pLeft->flags & EP_xIsSelect) ){
+      sqlite3SubselectError(pParse, nVector, 1);
+    }else{
+      sqlite3ErrorMsg(pParse, "row value misused");
+    }
+    return 1;
+  }
+  return 0;
+}
+#endif
+
+#ifndef SQLITE_OMIT_SUBQUERY
+/*
+** Generate code for an IN expression.
+**
+**      x IN (SELECT ...)
+**      x IN (value, value, ...)
+**
+** The left-hand side (LHS) is a scalar or vector expression.  The 
+** right-hand side (RHS) is an array of zero or more scalar values, or a
+** subquery.  If the RHS is a subquery, the number of result columns must
+** match the number of columns in the vector on the LHS.  If the RHS is
+** a list of values, the LHS must be a scalar. 
+**
+** The IN operator is true if the LHS value is contained within the RHS.
+** The result is false if the LHS is definitely not in the RHS.  The 
+** result is NULL if the presence of the LHS in the RHS cannot be 
+** determined due to NULLs.
+**
+** This routine generates code that jumps to destIfFalse if the LHS is not 
+** contained within the RHS.  If due to NULLs we cannot determine if the LHS
+** is contained in the RHS then jump to destIfNull.  If the LHS is contained
+** within the RHS then fall through.
+**
+** See the separate in-operator.md documentation file in the canonical
+** SQLite source tree for additional information.
+*/
+static void sqlite3ExprCodeIN(
+  Parse *pParse,        /* Parsing and code generating context */
+  Expr *pExpr,          /* The IN expression */
+  int destIfFalse,      /* Jump here if LHS is not contained in the RHS */
+  int destIfNull        /* Jump here if the results are unknown due to NULLs */
+){
+  int rRhsHasNull = 0;  /* Register that is true if RHS contains NULL values */
+  int eType;            /* Type of the RHS */
+  int rLhs;             /* Register(s) holding the LHS values */
+  int rLhsOrig;         /* LHS values prior to reordering by aiMap[] */
+  Vdbe *v;              /* Statement under construction */
+  int *aiMap = 0;       /* Map from vector field to index column */
+  char *zAff = 0;       /* Affinity string for comparisons */
+  int nVector;          /* Size of vectors for this IN operator */
+  int iDummy;           /* Dummy parameter to exprCodeVector() */
+  Expr *pLeft;          /* The LHS of the IN operator */
+  int i;                /* loop counter */
+  int destStep2;        /* Where to jump when NULLs seen in step 2 */
+  int destStep6 = 0;    /* Start of code for Step 6 */
+  int addrTruthOp;      /* Address of opcode that determines the IN is true */
+  int destNotNull;      /* Jump here if a comparison is not true in step 6 */
+  int addrTop;          /* Top of the step-6 loop */ 
+
+  pLeft = pExpr->pLeft;
+  if( sqlite3ExprCheckIN(pParse, pExpr) ) return;
+  zAff = exprINAffinity(pParse, pExpr);
+  nVector = sqlite3ExprVectorSize(pExpr->pLeft);
+  aiMap = (int*)sqlite3DbMallocZero(
+      pParse->db, nVector*(sizeof(int) + sizeof(char)) + 1
+  );
+  if( pParse->db->mallocFailed ) goto sqlite3ExprCodeIN_oom_error;
+
+  /* Attempt to compute the RHS. After this step, if anything other than
+  ** IN_INDEX_NOOP is returned, the table opened ith cursor pExpr->iTable 
+  ** contains the values that make up the RHS. If IN_INDEX_NOOP is returned,
+  ** the RHS has not yet been coded.  */
+  v = pParse->pVdbe;
+  assert( v!=0 );       /* OOM detected prior to this routine */
+  VdbeNoopComment((v, "begin IN expr"));
+  eType = sqlite3FindInIndex(pParse, pExpr,
+                             IN_INDEX_MEMBERSHIP | IN_INDEX_NOOP_OK,
+                             destIfFalse==destIfNull ? 0 : &rRhsHasNull, aiMap);
+
+  assert( pParse->nErr || nVector==1 || eType==IN_INDEX_EPH
+       || eType==IN_INDEX_INDEX_ASC || eType==IN_INDEX_INDEX_DESC 
+  );
+#ifdef SQLITE_DEBUG
+  /* Confirm that aiMap[] contains nVector integer values between 0 and
+  ** nVector-1. */
+  for(i=0; i<nVector; i++){
+    int j, cnt;
+    for(cnt=j=0; j<nVector; j++) if( aiMap[j]==i ) cnt++;
+    assert( cnt==1 );
+  }
+#endif
+
+  /* Code the LHS, the <expr> from "<expr> IN (...)". If the LHS is a 
+  ** vector, then it is stored in an array of nVector registers starting 
+  ** at r1.
+  **
+  ** sqlite3FindInIndex() might have reordered the fields of the LHS vector
+  ** so that the fields are in the same order as an existing index.   The
+  ** aiMap[] array contains a mapping from the original LHS field order to
+  ** the field order that matches the RHS index.
+  */
+  sqlite3ExprCachePush(pParse);
+  rLhsOrig = exprCodeVector(pParse, pLeft, &iDummy);
+  for(i=0; i<nVector && aiMap[i]==i; i++){} /* Are LHS fields reordered? */
+  if( i==nVector ){
+    /* LHS fields are not reordered */
+    rLhs = rLhsOrig;
+  }else{
+    /* Need to reorder the LHS fields according to aiMap */
+    rLhs = sqlite3GetTempRange(pParse, nVector);
+    for(i=0; i<nVector; i++){
+      sqlite3VdbeAddOp3(v, OP_Copy, rLhsOrig+i, rLhs+aiMap[i], 0);
+    }
+  }
+
+  /* If sqlite3FindInIndex() did not find or create an index that is
+  ** suitable for evaluating the IN operator, then evaluate using a
+  ** sequence of comparisons.
+  **
+  ** This is step (1) in the in-operator.md optimized algorithm.
+  */
+  if( eType==IN_INDEX_NOOP ){
+    ExprList *pList = pExpr->x.pList;
+    CollSeq *pColl = sqlite3ExprCollSeq(pParse, pExpr->pLeft);
+    int labelOk = sqlite3VdbeMakeLabel(v);
+    int r2, regToFree;
+    int regCkNull = 0;
+    int ii;
+    assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
+    if( destIfNull!=destIfFalse ){
+      regCkNull = sqlite3GetTempReg(pParse);
+      sqlite3VdbeAddOp3(v, OP_BitAnd, rLhs, rLhs, regCkNull);
+    }
+    for(ii=0; ii<pList->nExpr; ii++){
+      r2 = sqlite3ExprCodeTemp(pParse, pList->a[ii].pExpr, &regToFree);
+      if( regCkNull && sqlite3ExprCanBeNull(pList->a[ii].pExpr) ){
+        sqlite3VdbeAddOp3(v, OP_BitAnd, regCkNull, r2, regCkNull);
+      }
+      if( ii<pList->nExpr-1 || destIfNull!=destIfFalse ){
+        sqlite3VdbeAddOp4(v, OP_Eq, rLhs, labelOk, r2,
+                          (void*)pColl, P4_COLLSEQ);
+        VdbeCoverageIf(v, ii<pList->nExpr-1);
+        VdbeCoverageIf(v, ii==pList->nExpr-1);
+        sqlite3VdbeChangeP5(v, zAff[0]);
+      }else{
+        assert( destIfNull==destIfFalse );
+        sqlite3VdbeAddOp4(v, OP_Ne, rLhs, destIfFalse, r2,
+                          (void*)pColl, P4_COLLSEQ); VdbeCoverage(v);
+        sqlite3VdbeChangeP5(v, zAff[0] | SQLITE_JUMPIFNULL);
+      }
+      sqlite3ReleaseTempReg(pParse, regToFree);
+    }
+    if( regCkNull ){
+      sqlite3VdbeAddOp2(v, OP_IsNull, regCkNull, destIfNull); VdbeCoverage(v);
+      sqlite3VdbeGoto(v, destIfFalse);
+    }
+    sqlite3VdbeResolveLabel(v, labelOk);
+    sqlite3ReleaseTempReg(pParse, regCkNull);
+    goto sqlite3ExprCodeIN_finished;
+  }
+
+  /* Step 2: Check to see if the LHS contains any NULL columns.  If the
+  ** LHS does contain NULLs then the result must be either FALSE or NULL.
+  ** We will then skip the binary search of the RHS.
+  */
+  if( destIfNull==destIfFalse ){
+    destStep2 = destIfFalse;
+  }else{
+    destStep2 = destStep6 = sqlite3VdbeMakeLabel(v);
+  }
+  for(i=0; i<nVector; i++){
+    Expr *p = sqlite3VectorFieldSubexpr(pExpr->pLeft, i);
+    if( sqlite3ExprCanBeNull(p) ){
+      sqlite3VdbeAddOp2(v, OP_IsNull, rLhs+i, destStep2);
+      VdbeCoverage(v);
+    }
+  }
+
+  /* Step 3.  The LHS is now known to be non-NULL.  Do the binary search
+  ** of the RHS using the LHS as a probe.  If found, the result is
+  ** true.
+  */
+  if( eType==IN_INDEX_ROWID ){
+    /* In this case, the RHS is the ROWID of table b-tree and so we also
+    ** know that the RHS is non-NULL.  Hence, we combine steps 3 and 4
+    ** into a single opcode. */
+    sqlite3VdbeAddOp3(v, OP_SeekRowid, pExpr->iTable, destIfFalse, rLhs);
+    VdbeCoverage(v);
+    addrTruthOp = sqlite3VdbeAddOp0(v, OP_Goto);  /* Return True */
+  }else{
+    sqlite3VdbeAddOp4(v, OP_Affinity, rLhs, nVector, 0, zAff, nVector);
+    if( destIfFalse==destIfNull ){
+      /* Combine Step 3 and Step 5 into a single opcode */
+      sqlite3VdbeAddOp4Int(v, OP_NotFound, pExpr->iTable, destIfFalse,
+                           rLhs, nVector); VdbeCoverage(v);
+      goto sqlite3ExprCodeIN_finished;
+    }
+    /* Ordinary Step 3, for the case where FALSE and NULL are distinct */
+    addrTruthOp = sqlite3VdbeAddOp4Int(v, OP_Found, pExpr->iTable, 0,
+                                      rLhs, nVector); VdbeCoverage(v);
+  }
+
+  /* Step 4.  If the RHS is known to be non-NULL and we did not find
+  ** an match on the search above, then the result must be FALSE.
+  */
+  if( rRhsHasNull && nVector==1 ){
+    sqlite3VdbeAddOp2(v, OP_NotNull, rRhsHasNull, destIfFalse);
+    VdbeCoverage(v);
+  }
+
+  /* Step 5.  If we do not care about the difference between NULL and
+  ** FALSE, then just return false. 
+  */
+  if( destIfFalse==destIfNull ) sqlite3VdbeGoto(v, destIfFalse);
+
+  /* Step 6: Loop through rows of the RHS.  Compare each row to the LHS.
+  ** If any comparison is NULL, then the result is NULL.  If all
+  ** comparisons are FALSE then the final result is FALSE.
+  **
+  ** For a scalar LHS, it is sufficient to check just the first row
+  ** of the RHS.
+  */
+  if( destStep6 ) sqlite3VdbeResolveLabel(v, destStep6);
+  addrTop = sqlite3VdbeAddOp2(v, OP_Rewind, pExpr->iTable, destIfFalse);
+  VdbeCoverage(v);
+  if( nVector>1 ){
+    destNotNull = sqlite3VdbeMakeLabel(v);
+  }else{
+    /* For nVector==1, combine steps 6 and 7 by immediately returning
+    ** FALSE if the first comparison is not NULL */
+    destNotNull = destIfFalse;
+  }
+  for(i=0; i<nVector; i++){
+    Expr *p;
+    CollSeq *pColl;
+    int r3 = sqlite3GetTempReg(pParse);
+    p = sqlite3VectorFieldSubexpr(pLeft, i);
+    pColl = sqlite3ExprCollSeq(pParse, p);
+    sqlite3VdbeAddOp3(v, OP_Column, pExpr->iTable, i, r3);
+    sqlite3VdbeAddOp4(v, OP_Ne, rLhs+i, destNotNull, r3,
+                      (void*)pColl, P4_COLLSEQ);
+    VdbeCoverage(v);
+    sqlite3ReleaseTempReg(pParse, r3);
+  }
+  sqlite3VdbeAddOp2(v, OP_Goto, 0, destIfNull);
+  if( nVector>1 ){
+    sqlite3VdbeResolveLabel(v, destNotNull);
+    sqlite3VdbeAddOp2(v, OP_Next, pExpr->iTable, addrTop+1);
+    VdbeCoverage(v);
+
+    /* Step 7:  If we reach this point, we know that the result must
+    ** be false. */
+    sqlite3VdbeAddOp2(v, OP_Goto, 0, destIfFalse);
+  }
+
+  /* Jumps here in order to return true. */
+  sqlite3VdbeJumpHere(v, addrTruthOp);
+
+sqlite3ExprCodeIN_finished:
+  if( rLhs!=rLhsOrig ) sqlite3ReleaseTempReg(pParse, rLhs);
+  sqlite3ExprCachePop(pParse);
+  VdbeComment((v, "end IN expr"));
+sqlite3ExprCodeIN_oom_error:
+  sqlite3DbFree(pParse->db, aiMap);
+  sqlite3DbFree(pParse->db, zAff);
+}
+#endif /* SQLITE_OMIT_SUBQUERY */
+
+#ifndef SQLITE_OMIT_FLOATING_POINT
+/*
+** Generate an instruction that will put the floating point
+** value described by z[0..n-1] into register iMem.
+**
+** The z[] string will probably not be zero-terminated.  But the 
+** z[n] character is guaranteed to be something that does not look
+** like the continuation of the number.
+*/
+static void codeReal(Vdbe *v, const char *z, int negateFlag, int iMem){
+  if( ALWAYS(z!=0) ){
+    double value;
+    sqlite3AtoF(z, &value, sqlite3Strlen30(z), SQLITE_UTF8);
+    assert( !sqlite3IsNaN(value) ); /* The new AtoF never returns NaN */
+    if( negateFlag ) value = -value;
+    sqlite3VdbeAddOp4Dup8(v, OP_Real, 0, iMem, 0, (u8*)&value, P4_REAL);
+  }
+}
+#endif
+
+
+/*
+** Generate an instruction that will put the integer describe by
+** text z[0..n-1] into register iMem.
+**
+** Expr.u.zToken is always UTF8 and zero-terminated.
+*/
+static void codeInteger(Parse *pParse, Expr *pExpr, int negFlag, int iMem){
+  Vdbe *v = pParse->pVdbe;
+  if( pExpr->flags & EP_IntValue ){
+    int i = pExpr->u.iValue;
+    assert( i>=0 );
+    if( negFlag ) i = -i;
+    sqlite3VdbeAddOp2(v, OP_Integer, i, iMem);
+  }else{
+    int c;
+    i64 value;
+    const char *z = pExpr->u.zToken;
+    assert( z!=0 );
+    c = sqlite3DecOrHexToI64(z, &value);
+    if( c==0 || (c==2 && negFlag) ){
+      if( negFlag ){ value = c==2 ? SMALLEST_INT64 : -value; }
+      sqlite3VdbeAddOp4Dup8(v, OP_Int64, 0, iMem, 0, (u8*)&value, P4_INT64);
+    }else{
+#ifdef SQLITE_OMIT_FLOATING_POINT
+      sqlite3ErrorMsg(pParse, "oversized integer: %s%s", negFlag ? "-" : "", z);
+#else
+#ifndef SQLITE_OMIT_HEX_INTEGER
+      if( sqlite3_strnicmp(z,"0x",2)==0 ){
+        sqlite3ErrorMsg(pParse, "hex literal too big: %s", z);
+      }else
+#endif
+      {
+        codeReal(v, z, negFlag, iMem);
+      }
+#endif
+    }
+  }
+}
+
+/*
+** Erase column-cache entry number i
+*/
+static void cacheEntryClear(Parse *pParse, int i){
+  if( pParse->aColCache[i].tempReg ){
+    if( pParse->nTempReg<ArraySize(pParse->aTempReg) ){
+      pParse->aTempReg[pParse->nTempReg++] = pParse->aColCache[i].iReg;
+    }
+  }
+  pParse->nColCache--;
+  if( i<pParse->nColCache ){
+    pParse->aColCache[i] = pParse->aColCache[pParse->nColCache];
+  }
+}
+
+
+/*
+** Record in the column cache that a particular column from a
+** particular table is stored in a particular register.
+*/
+SQLITE_PRIVATE void sqlite3ExprCacheStore(Parse *pParse, int iTab, int iCol, int iReg){
+  int i;
+  int minLru;
+  int idxLru;
+  struct yColCache *p;
+
+  /* Unless an error has occurred, register numbers are always positive. */
+  assert( iReg>0 || pParse->nErr || pParse->db->mallocFailed );
+  assert( iCol>=-1 && iCol<32768 );  /* Finite column numbers */
+
+  /* The SQLITE_ColumnCache flag disables the column cache.  This is used
+  ** for testing only - to verify that SQLite always gets the same answer
+  ** with and without the column cache.
+  */
+  if( OptimizationDisabled(pParse->db, SQLITE_ColumnCache) ) return;
+
+  /* First replace any existing entry.
+  **
+  ** Actually, the way the column cache is currently used, we are guaranteed
+  ** that the object will never already be in cache.  Verify this guarantee.
+  */
+#ifndef NDEBUG
+  for(i=0, p=pParse->aColCache; i<pParse->nColCache; i++, p++){
+    assert( p->iTable!=iTab || p->iColumn!=iCol );
+  }
+#endif
+
+  /* If the cache is already full, delete the least recently used entry */
+  if( pParse->nColCache>=SQLITE_N_COLCACHE ){
+    minLru = 0x7fffffff;
+    idxLru = -1;
+    for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
+      if( p->lru<minLru ){
+        idxLru = i;
+        minLru = p->lru;
+      }
+    }
+    p = &pParse->aColCache[idxLru];
+  }else{
+    p = &pParse->aColCache[pParse->nColCache++];
+  }
+
+  /* Add the new entry to the end of the cache */
+  p->iLevel = pParse->iCacheLevel;
+  p->iTable = iTab;
+  p->iColumn = iCol;
+  p->iReg = iReg;
+  p->tempReg = 0;
+  p->lru = pParse->iCacheCnt++;
+}
+
+/*
+** Indicate that registers between iReg..iReg+nReg-1 are being overwritten.
+** Purge the range of registers from the column cache.
+*/
+SQLITE_PRIVATE void sqlite3ExprCacheRemove(Parse *pParse, int iReg, int nReg){
+  int i = 0;
+  while( i<pParse->nColCache ){
+    struct yColCache *p = &pParse->aColCache[i];
+    if( p->iReg >= iReg && p->iReg < iReg+nReg ){
+      cacheEntryClear(pParse, i);
+    }else{
+      i++;
+    }
+  }
+}
+
+/*
+** Remember the current column cache context.  Any new entries added
+** added to the column cache after this call are removed when the
+** corresponding pop occurs.
+*/
+SQLITE_PRIVATE void sqlite3ExprCachePush(Parse *pParse){
+  pParse->iCacheLevel++;
+#ifdef SQLITE_DEBUG
+  if( pParse->db->flags & SQLITE_VdbeAddopTrace ){
+    printf("PUSH to %d\n", pParse->iCacheLevel);
+  }
+#endif
+}
+
+/*
+** Remove from the column cache any entries that were added since the
+** the previous sqlite3ExprCachePush operation.  In other words, restore
+** the cache to the state it was in prior the most recent Push.
+*/
+SQLITE_PRIVATE void sqlite3ExprCachePop(Parse *pParse){
+  int i = 0;
+  assert( pParse->iCacheLevel>=1 );
+  pParse->iCacheLevel--;
+#ifdef SQLITE_DEBUG
+  if( pParse->db->flags & SQLITE_VdbeAddopTrace ){
+    printf("POP  to %d\n", pParse->iCacheLevel);
+  }
+#endif
+  while( i<pParse->nColCache ){
+    if( pParse->aColCache[i].iLevel>pParse->iCacheLevel ){
+      cacheEntryClear(pParse, i);
+    }else{
+      i++;
+    }
+  }
+}
+
+/*
+** When a cached column is reused, make sure that its register is
+** no longer available as a temp register.  ticket #3879:  that same
+** register might be in the cache in multiple places, so be sure to
+** get them all.
+*/
+static void sqlite3ExprCachePinRegister(Parse *pParse, int iReg){
+  int i;
+  struct yColCache *p;
+  for(i=0, p=pParse->aColCache; i<pParse->nColCache; i++, p++){
+    if( p->iReg==iReg ){
+      p->tempReg = 0;
+    }
+  }
+}
+
+/* Generate code that will load into register regOut a value that is
+** appropriate for the iIdxCol-th column of index pIdx.
+*/
+SQLITE_PRIVATE void sqlite3ExprCodeLoadIndexColumn(
+  Parse *pParse,  /* The parsing context */
+  Index *pIdx,    /* The index whose column is to be loaded */
+  int iTabCur,    /* Cursor pointing to a table row */
+  int iIdxCol,    /* The column of the index to be loaded */
+  int regOut      /* Store the index column value in this register */
+){
+  i16 iTabCol = pIdx->aiColumn[iIdxCol];
+  if( iTabCol==XN_EXPR ){
+    assert( pIdx->aColExpr );
+    assert( pIdx->aColExpr->nExpr>iIdxCol );
+    pParse->iSelfTab = iTabCur;
+    sqlite3ExprCodeCopy(pParse, pIdx->aColExpr->a[iIdxCol].pExpr, regOut);
+  }else{
+    sqlite3ExprCodeGetColumnOfTable(pParse->pVdbe, pIdx->pTable, iTabCur,
+                                    iTabCol, regOut);
+  }
+}
+
+/*
+** Generate code to extract the value of the iCol-th column of a table.
+*/
+SQLITE_PRIVATE void sqlite3ExprCodeGetColumnOfTable(
+  Vdbe *v,        /* The VDBE under construction */
+  Table *pTab,    /* The table containing the value */
+  int iTabCur,    /* The table cursor.  Or the PK cursor for WITHOUT ROWID */
+  int iCol,       /* Index of the column to extract */
+  int regOut      /* Extract the value into this register */
+){
+  if( iCol<0 || iCol==pTab->iPKey ){
+    sqlite3VdbeAddOp2(v, OP_Rowid, iTabCur, regOut);
+  }else{
+    int op = IsVirtual(pTab) ? OP_VColumn : OP_Column;
+    int x = iCol;
+    if( !HasRowid(pTab) && !IsVirtual(pTab) ){
+      x = sqlite3ColumnOfIndex(sqlite3PrimaryKeyIndex(pTab), iCol);
+    }
+    sqlite3VdbeAddOp3(v, op, iTabCur, x, regOut);
+  }
+  if( iCol>=0 ){
+    sqlite3ColumnDefault(v, pTab, iCol, regOut);
+  }
+}
+
+/*
+** Generate code that will extract the iColumn-th column from
+** table pTab and store the column value in a register. 
+**
+** An effort is made to store the column value in register iReg.  This
+** is not garanteeed for GetColumn() - the result can be stored in
+** any register.  But the result is guaranteed to land in register iReg
+** for GetColumnToReg().
+**
+** There must be an open cursor to pTab in iTable when this routine
+** is called.  If iColumn<0 then code is generated that extracts the rowid.
+*/
+SQLITE_PRIVATE int sqlite3ExprCodeGetColumn(
+  Parse *pParse,   /* Parsing and code generating context */
+  Table *pTab,     /* Description of the table we are reading from */
+  int iColumn,     /* Index of the table column */
+  int iTable,      /* The cursor pointing to the table */
+  int iReg,        /* Store results here */
+  u8 p5            /* P5 value for OP_Column + FLAGS */
+){
+  Vdbe *v = pParse->pVdbe;
+  int i;
+  struct yColCache *p;
+
+  for(i=0, p=pParse->aColCache; i<pParse->nColCache; i++, p++){
+    if( p->iTable==iTable && p->iColumn==iColumn ){
+      p->lru = pParse->iCacheCnt++;
+      sqlite3ExprCachePinRegister(pParse, p->iReg);
+      return p->iReg;
+    }
+  }  
+  assert( v!=0 );
+  sqlite3ExprCodeGetColumnOfTable(v, pTab, iTable, iColumn, iReg);
+  if( p5 ){
+    sqlite3VdbeChangeP5(v, p5);
+  }else{   
+    sqlite3ExprCacheStore(pParse, iTable, iColumn, iReg);
+  }
+  return iReg;
+}
+SQLITE_PRIVATE void sqlite3ExprCodeGetColumnToReg(
+  Parse *pParse,   /* Parsing and code generating context */
+  Table *pTab,     /* Description of the table we are reading from */
+  int iColumn,     /* Index of the table column */
+  int iTable,      /* The cursor pointing to the table */
+  int iReg         /* Store results here */
+){
+  int r1 = sqlite3ExprCodeGetColumn(pParse, pTab, iColumn, iTable, iReg, 0);
+  if( r1!=iReg ) sqlite3VdbeAddOp2(pParse->pVdbe, OP_SCopy, r1, iReg);
+}
+
+
+/*
+** Clear all column cache entries.
+*/
+SQLITE_PRIVATE void sqlite3ExprCacheClear(Parse *pParse){
+  int i;
+
+#if SQLITE_DEBUG
+  if( pParse->db->flags & SQLITE_VdbeAddopTrace ){
+    printf("CLEAR\n");
+  }
+#endif
+  for(i=0; i<pParse->nColCache; i++){
+    if( pParse->aColCache[i].tempReg
+     && pParse->nTempReg<ArraySize(pParse->aTempReg)
+    ){
+       pParse->aTempReg[pParse->nTempReg++] = pParse->aColCache[i].iReg;
+    }
+  }
+  pParse->nColCache = 0;
+}
+
+/*
+** Record the fact that an affinity change has occurred on iCount
+** registers starting with iStart.
+*/
+SQLITE_PRIVATE void sqlite3ExprCacheAffinityChange(Parse *pParse, int iStart, int iCount){
+  sqlite3ExprCacheRemove(pParse, iStart, iCount);
+}
+
+/*
+** Generate code to move content from registers iFrom...iFrom+nReg-1
+** over to iTo..iTo+nReg-1. Keep the column cache up-to-date.
+*/
+SQLITE_PRIVATE void sqlite3ExprCodeMove(Parse *pParse, int iFrom, int iTo, int nReg){
+  assert( iFrom>=iTo+nReg || iFrom+nReg<=iTo );
+  sqlite3VdbeAddOp3(pParse->pVdbe, OP_Move, iFrom, iTo, nReg);
+  sqlite3ExprCacheRemove(pParse, iFrom, nReg);
+}
+
+#if defined(SQLITE_DEBUG) || defined(SQLITE_COVERAGE_TEST)
+/*
+** Return true if any register in the range iFrom..iTo (inclusive)
+** is used as part of the column cache.
+**
+** This routine is used within assert() and testcase() macros only
+** and does not appear in a normal build.
+*/
+static int usedAsColumnCache(Parse *pParse, int iFrom, int iTo){
+  int i;
+  struct yColCache *p;
+  for(i=0, p=pParse->aColCache; i<pParse->nColCache; i++, p++){
+    int r = p->iReg;
+    if( r>=iFrom && r<=iTo ) return 1;    /*NO_TEST*/
+  }
+  return 0;
+}
+#endif /* SQLITE_DEBUG || SQLITE_COVERAGE_TEST */
+
+
+/*
+** Convert a scalar expression node to a TK_REGISTER referencing
+** register iReg.  The caller must ensure that iReg already contains
+** the correct value for the expression.
+*/
+static void exprToRegister(Expr *p, int iReg){
+  p->op2 = p->op;
+  p->op = TK_REGISTER;
+  p->iTable = iReg;
+  ExprClearProperty(p, EP_Skip);
+}
+
+/*
+** Evaluate an expression (either a vector or a scalar expression) and store
+** the result in continguous temporary registers.  Return the index of
+** the first register used to store the result.
+**
+** If the returned result register is a temporary scalar, then also write
+** that register number into *piFreeable.  If the returned result register
+** is not a temporary or if the expression is a vector set *piFreeable
+** to 0.
+*/
+static int exprCodeVector(Parse *pParse, Expr *p, int *piFreeable){
+  int iResult;
+  int nResult = sqlite3ExprVectorSize(p);
+  if( nResult==1 ){
+    iResult = sqlite3ExprCodeTemp(pParse, p, piFreeable);
+  }else{
+    *piFreeable = 0;
+    if( p->op==TK_SELECT ){
+      iResult = sqlite3CodeSubselect(pParse, p, 0, 0);
+    }else{
+      int i;
+      iResult = pParse->nMem+1;
+      pParse->nMem += nResult;
+      for(i=0; i<nResult; i++){
+        sqlite3ExprCodeFactorable(pParse, p->x.pList->a[i].pExpr, i+iResult);
+      }
+    }
+  }
+  return iResult;
+}
+
+
+/*
+** Generate code into the current Vdbe to evaluate the given
+** expression.  Attempt to store the results in register "target".
+** Return the register where results are stored.
+**
+** With this routine, there is no guarantee that results will
+** be stored in target.  The result might be stored in some other
+** register if it is convenient to do so.  The calling function
+** must check the return code and move the results to the desired
+** register.
+*/
+SQLITE_PRIVATE int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
+  Vdbe *v = pParse->pVdbe;  /* The VM under construction */
+  int op;                   /* The opcode being coded */
+  int inReg = target;       /* Results stored in register inReg */
+  int regFree1 = 0;         /* If non-zero free this temporary register */
+  int regFree2 = 0;         /* If non-zero free this temporary register */
+  int r1, r2;               /* Various register numbers */
+  Expr tempX;               /* Temporary expression node */
+  int p5 = 0;
+
+  assert( target>0 && target<=pParse->nMem );
+  if( v==0 ){
+    assert( pParse->db->mallocFailed );
+    return 0;
+  }
+
+  if( pExpr==0 ){
+    op = TK_NULL;
+  }else{
+    op = pExpr->op;
+  }
+  switch( op ){
+    case TK_AGG_COLUMN: {
+      AggInfo *pAggInfo = pExpr->pAggInfo;
+      struct AggInfo_col *pCol = &pAggInfo->aCol[pExpr->iAgg];
+      if( !pAggInfo->directMode ){
+        assert( pCol->iMem>0 );
+        return pCol->iMem;
+      }else if( pAggInfo->useSortingIdx ){
+        sqlite3VdbeAddOp3(v, OP_Column, pAggInfo->sortingIdxPTab,
+                              pCol->iSorterColumn, target);
+        return target;
+      }
+      /* Otherwise, fall thru into the TK_COLUMN case */
+    }
+    case TK_COLUMN: {
+      int iTab = pExpr->iTable;
+      if( iTab<0 ){
+        if( pParse->ckBase>0 ){
+          /* Generating CHECK constraints or inserting into partial index */
+          return pExpr->iColumn + pParse->ckBase;
+        }else{
+          /* Coding an expression that is part of an index where column names
+          ** in the index refer to the table to which the index belongs */
+          iTab = pParse->iSelfTab;
+        }
+      }
+      return sqlite3ExprCodeGetColumn(pParse, pExpr->pTab,
+                               pExpr->iColumn, iTab, target,
+                               pExpr->op2);
+    }
+    case TK_INTEGER: {
+      codeInteger(pParse, pExpr, 0, target);
+      return target;
+    }
+#ifndef SQLITE_OMIT_FLOATING_POINT
+    case TK_FLOAT: {
+      assert( !ExprHasProperty(pExpr, EP_IntValue) );
+      codeReal(v, pExpr->u.zToken, 0, target);
+      return target;
+    }
+#endif
+    case TK_STRING: {
+      assert( !ExprHasProperty(pExpr, EP_IntValue) );
+      sqlite3VdbeLoadString(v, target, pExpr->u.zToken);
+      return target;
+    }
+    case TK_NULL: {
+      sqlite3VdbeAddOp2(v, OP_Null, 0, target);
+      return target;
+    }
+#ifndef SQLITE_OMIT_BLOB_LITERAL
+    case TK_BLOB: {
+      int n;
+      const char *z;
+      char *zBlob;
+      assert( !ExprHasProperty(pExpr, EP_IntValue) );
+      assert( pExpr->u.zToken[0]=='x' || pExpr->u.zToken[0]=='X' );
+      assert( pExpr->u.zToken[1]=='\'' );
+      z = &pExpr->u.zToken[2];
+      n = sqlite3Strlen30(z) - 1;
+      assert( z[n]=='\'' );
+      zBlob = sqlite3HexToBlob(sqlite3VdbeDb(v), z, n);
+      sqlite3VdbeAddOp4(v, OP_Blob, n/2, target, 0, zBlob, P4_DYNAMIC);
+      return target;
+    }
+#endif
+    case TK_VARIABLE: {
+      assert( !ExprHasProperty(pExpr, EP_IntValue) );
+      assert( pExpr->u.zToken!=0 );
+      assert( pExpr->u.zToken[0]!=0 );
+      sqlite3VdbeAddOp2(v, OP_Variable, pExpr->iColumn, target);
+      if( pExpr->u.zToken[1]!=0 ){
+        assert( pExpr->u.zToken[0]=='?' 
+             || strcmp(pExpr->u.zToken, pParse->azVar[pExpr->iColumn-1])==0 );
+        sqlite3VdbeChangeP4(v, -1, pParse->azVar[pExpr->iColumn-1], P4_STATIC);
+      }
+      return target;
+    }
+    case TK_REGISTER: {
+      return pExpr->iTable;
+    }
+#ifndef SQLITE_OMIT_CAST
+    case TK_CAST: {
+      /* Expressions of the form:   CAST(pLeft AS token) */
+      inReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);
+      if( inReg!=target ){
+        sqlite3VdbeAddOp2(v, OP_SCopy, inReg, target);
+        inReg = target;
+      }
+      sqlite3VdbeAddOp2(v, OP_Cast, target,
+                        sqlite3AffinityType(pExpr->u.zToken, 0));
+      testcase( usedAsColumnCache(pParse, inReg, inReg) );
+      sqlite3ExprCacheAffinityChange(pParse, inReg, 1);
+      return inReg;
+    }
+#endif /* SQLITE_OMIT_CAST */
+    case TK_IS:
+    case TK_ISNOT:
+      op = (op==TK_IS) ? TK_EQ : TK_NE;
+      p5 = SQLITE_NULLEQ;
+      /* fall-through */
+    case TK_LT:
+    case TK_LE:
+    case TK_GT:
+    case TK_GE:
+    case TK_NE:
+    case TK_EQ: {
+      Expr *pLeft = pExpr->pLeft;
+      if( sqlite3ExprIsVector(pLeft) ){
+        codeVectorCompare(pParse, pExpr, target, op, p5);
+      }else{
+        r1 = sqlite3ExprCodeTemp(pParse, pLeft, &regFree1);
+        r2 = sqlite3ExprCodeTemp(pParse, pExpr->pRight, &regFree2);
+        codeCompare(pParse, pLeft, pExpr->pRight, op,
+            r1, r2, inReg, SQLITE_STOREP2 | p5);
+        assert(TK_LT==OP_Lt); testcase(op==OP_Lt); VdbeCoverageIf(v,op==OP_Lt);
+        assert(TK_LE==OP_Le); testcase(op==OP_Le); VdbeCoverageIf(v,op==OP_Le);
+        assert(TK_GT==OP_Gt); testcase(op==OP_Gt); VdbeCoverageIf(v,op==OP_Gt);
+        assert(TK_GE==OP_Ge); testcase(op==OP_Ge); VdbeCoverageIf(v,op==OP_Ge);
+        assert(TK_EQ==OP_Eq); testcase(op==OP_Eq); VdbeCoverageIf(v,op==OP_Eq);
+        assert(TK_NE==OP_Ne); testcase(op==OP_Ne); VdbeCoverageIf(v,op==OP_Ne);
+        testcase( regFree1==0 );
+        testcase( regFree2==0 );
+      }
+      break;
+    }
+    case TK_AND:
+    case TK_OR:
+    case TK_PLUS:
+    case TK_STAR:
+    case TK_MINUS:
+    case TK_REM:
+    case TK_BITAND:
+    case TK_BITOR:
+    case TK_SLASH:
+    case TK_LSHIFT:
+    case TK_RSHIFT: 
+    case TK_CONCAT: {
+      assert( TK_AND==OP_And );            testcase( op==TK_AND );
+      assert( TK_OR==OP_Or );              testcase( op==TK_OR );
+      assert( TK_PLUS==OP_Add );           testcase( op==TK_PLUS );
+      assert( TK_MINUS==OP_Subtract );     testcase( op==TK_MINUS );
+      assert( TK_REM==OP_Remainder );      testcase( op==TK_REM );
+      assert( TK_BITAND==OP_BitAnd );      testcase( op==TK_BITAND );
+      assert( TK_BITOR==OP_BitOr );        testcase( op==TK_BITOR );
+      assert( TK_SLASH==OP_Divide );       testcase( op==TK_SLASH );
+      assert( TK_LSHIFT==OP_ShiftLeft );   testcase( op==TK_LSHIFT );
+      assert( TK_RSHIFT==OP_ShiftRight );  testcase( op==TK_RSHIFT );
+      assert( TK_CONCAT==OP_Concat );      testcase( op==TK_CONCAT );
+      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
+      r2 = sqlite3ExprCodeTemp(pParse, pExpr->pRight, &regFree2);
+      sqlite3VdbeAddOp3(v, op, r2, r1, target);
+      testcase( regFree1==0 );
+      testcase( regFree2==0 );
+      break;
+    }
+    case TK_UMINUS: {
+      Expr *pLeft = pExpr->pLeft;
+      assert( pLeft );
+      if( pLeft->op==TK_INTEGER ){
+        codeInteger(pParse, pLeft, 1, target);
+        return target;
+#ifndef SQLITE_OMIT_FLOATING_POINT
+      }else if( pLeft->op==TK_FLOAT ){
+        assert( !ExprHasProperty(pExpr, EP_IntValue) );
+        codeReal(v, pLeft->u.zToken, 1, target);
+        return target;
+#endif
+      }else{
+        tempX.op = TK_INTEGER;
+        tempX.flags = EP_IntValue|EP_TokenOnly;
+        tempX.u.iValue = 0;
+        r1 = sqlite3ExprCodeTemp(pParse, &tempX, &regFree1);
+        r2 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree2);
+        sqlite3VdbeAddOp3(v, OP_Subtract, r2, r1, target);
+        testcase( regFree2==0 );
+      }
+      break;
+    }
+    case TK_BITNOT:
+    case TK_NOT: {
+      assert( TK_BITNOT==OP_BitNot );   testcase( op==TK_BITNOT );
+      assert( TK_NOT==OP_Not );         testcase( op==TK_NOT );
+      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
+      testcase( regFree1==0 );
+      sqlite3VdbeAddOp2(v, op, r1, inReg);
+      break;
+    }
+    case TK_ISNULL:
+    case TK_NOTNULL: {
+      int addr;
+      assert( TK_ISNULL==OP_IsNull );   testcase( op==TK_ISNULL );
+      assert( TK_NOTNULL==OP_NotNull ); testcase( op==TK_NOTNULL );
+      sqlite3VdbeAddOp2(v, OP_Integer, 1, target);
+      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
+      testcase( regFree1==0 );
+      addr = sqlite3VdbeAddOp1(v, op, r1);
+      VdbeCoverageIf(v, op==TK_ISNULL);
+      VdbeCoverageIf(v, op==TK_NOTNULL);
+      sqlite3VdbeAddOp2(v, OP_Integer, 0, target);
+      sqlite3VdbeJumpHere(v, addr);
+      break;
+    }
+    case TK_AGG_FUNCTION: {
+      AggInfo *pInfo = pExpr->pAggInfo;
+      if( pInfo==0 ){
+        assert( !ExprHasProperty(pExpr, EP_IntValue) );
+        sqlite3ErrorMsg(pParse, "misuse of aggregate: %s()", pExpr->u.zToken);
+      }else{
+        return pInfo->aFunc[pExpr->iAgg].iMem;
+      }
+      break;
+    }
+    case TK_FUNCTION: {
+      ExprList *pFarg;       /* List of function arguments */
+      int nFarg;             /* Number of function arguments */
+      FuncDef *pDef;         /* The function definition object */
+      const char *zId;       /* The function name */
+      u32 constMask = 0;     /* Mask of function arguments that are constant */
+      int i;                 /* Loop counter */
+      sqlite3 *db = pParse->db;  /* The database connection */
+      u8 enc = ENC(db);      /* The text encoding used by this database */
+      CollSeq *pColl = 0;    /* A collating sequence */
+
+      assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
+      if( ExprHasProperty(pExpr, EP_TokenOnly) ){
+        pFarg = 0;
+      }else{
+        pFarg = pExpr->x.pList;
+      }
+      nFarg = pFarg ? pFarg->nExpr : 0;
+      assert( !ExprHasProperty(pExpr, EP_IntValue) );
+      zId = pExpr->u.zToken;
+      pDef = sqlite3FindFunction(db, zId, nFarg, enc, 0);
+#ifdef SQLITE_ENABLE_UNKNOWN_SQL_FUNCTION
+      if( pDef==0 && pParse->explain ){
+        pDef = sqlite3FindFunction(db, "unknown", nFarg, enc, 0);
+      }
+#endif
+      if( pDef==0 || pDef->xFinalize!=0 ){
+        sqlite3ErrorMsg(pParse, "unknown function: %s()", zId);
+        break;
+      }
+
+      /* Attempt a direct implementation of the built-in COALESCE() and
+      ** IFNULL() functions.  This avoids unnecessary evaluation of
+      ** arguments past the first non-NULL argument.
+      */
+      if( pDef->funcFlags & SQLITE_FUNC_COALESCE ){
+        int endCoalesce = sqlite3VdbeMakeLabel(v);
+        assert( nFarg>=2 );
+        sqlite3ExprCode(pParse, pFarg->a[0].pExpr, target);
+        for(i=1; i<nFarg; i++){
+          sqlite3VdbeAddOp2(v, OP_NotNull, target, endCoalesce);
+          VdbeCoverage(v);
+          sqlite3ExprCacheRemove(pParse, target, 1);
+          sqlite3ExprCachePush(pParse);
+          sqlite3ExprCode(pParse, pFarg->a[i].pExpr, target);
+          sqlite3ExprCachePop(pParse);
+        }
+        sqlite3VdbeResolveLabel(v, endCoalesce);
+        break;
+      }
+
+      /* The UNLIKELY() function is a no-op.  The result is the value
+      ** of the first argument.
+      */
+      if( pDef->funcFlags & SQLITE_FUNC_UNLIKELY ){
+        assert( nFarg>=1 );
+        return sqlite3ExprCodeTarget(pParse, pFarg->a[0].pExpr, target);
+      }
+
+      for(i=0; i<nFarg; i++){
+        if( i<32 && sqlite3ExprIsConstant(pFarg->a[i].pExpr) ){
+          testcase( i==31 );
+          constMask |= MASKBIT32(i);
+        }
+        if( (pDef->funcFlags & SQLITE_FUNC_NEEDCOLL)!=0 && !pColl ){
+          pColl = sqlite3ExprCollSeq(pParse, pFarg->a[i].pExpr);
+        }
+      }
+      if( pFarg ){
+        if( constMask ){
+          r1 = pParse->nMem+1;
+          pParse->nMem += nFarg;
+        }else{
+          r1 = sqlite3GetTempRange(pParse, nFarg);
+        }
+
+        /* For length() and typeof() functions with a column argument,
+        ** set the P5 parameter to the OP_Column opcode to OPFLAG_LENGTHARG
+        ** or OPFLAG_TYPEOFARG respectively, to avoid unnecessary data
+        ** loading.
+        */
+        if( (pDef->funcFlags & (SQLITE_FUNC_LENGTH|SQLITE_FUNC_TYPEOF))!=0 ){
+          u8 exprOp;
+          assert( nFarg==1 );
+          assert( pFarg->a[0].pExpr!=0 );
+          exprOp = pFarg->a[0].pExpr->op;
+          if( exprOp==TK_COLUMN || exprOp==TK_AGG_COLUMN ){
+            assert( SQLITE_FUNC_LENGTH==OPFLAG_LENGTHARG );
+            assert( SQLITE_FUNC_TYPEOF==OPFLAG_TYPEOFARG );
+            testcase( pDef->funcFlags & OPFLAG_LENGTHARG );
+            pFarg->a[0].pExpr->op2 = 
+                  pDef->funcFlags & (OPFLAG_LENGTHARG|OPFLAG_TYPEOFARG);
+          }
+        }
+
+        sqlite3ExprCachePush(pParse);     /* Ticket 2ea2425d34be */
+        sqlite3ExprCodeExprList(pParse, pFarg, r1, 0,
+                                SQLITE_ECEL_DUP|SQLITE_ECEL_FACTOR);
+        sqlite3ExprCachePop(pParse);      /* Ticket 2ea2425d34be */
+      }else{
+        r1 = 0;
+      }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+      /* Possibly overload the function if the first argument is
+      ** a virtual table column.
+      **
+      ** For infix functions (LIKE, GLOB, REGEXP, and MATCH) use the
+      ** second argument, not the first, as the argument to test to
+      ** see if it is a column in a virtual table.  This is done because
+      ** the left operand of infix functions (the operand we want to
+      ** control overloading) ends up as the second argument to the
+      ** function.  The expression "A glob B" is equivalent to 
+      ** "glob(B,A).  We want to use the A in "A glob B" to test
+      ** for function overloading.  But we use the B term in "glob(B,A)".
+      */
+      if( nFarg>=2 && (pExpr->flags & EP_InfixFunc) ){
+        pDef = sqlite3VtabOverloadFunction(db, pDef, nFarg, pFarg->a[1].pExpr);
+      }else if( nFarg>0 ){
+        pDef = sqlite3VtabOverloadFunction(db, pDef, nFarg, pFarg->a[0].pExpr);
+      }
+#endif
+      if( pDef->funcFlags & SQLITE_FUNC_NEEDCOLL ){
+        if( !pColl ) pColl = db->pDfltColl; 
+        sqlite3VdbeAddOp4(v, OP_CollSeq, 0, 0, 0, (char *)pColl, P4_COLLSEQ);
+      }
+      sqlite3VdbeAddOp4(v, OP_Function0, constMask, r1, target,
+                        (char*)pDef, P4_FUNCDEF);
+      sqlite3VdbeChangeP5(v, (u8)nFarg);
+      if( nFarg && constMask==0 ){
+        sqlite3ReleaseTempRange(pParse, r1, nFarg);
+      }
+      return target;
+    }
+#ifndef SQLITE_OMIT_SUBQUERY
+    case TK_EXISTS:
+    case TK_SELECT: {
+      int nCol;
+      testcase( op==TK_EXISTS );
+      testcase( op==TK_SELECT );
+      if( op==TK_SELECT && (nCol = pExpr->x.pSelect->pEList->nExpr)!=1 ){
+        sqlite3SubselectError(pParse, nCol, 1);
+      }else{
+        return sqlite3CodeSubselect(pParse, pExpr, 0, 0);
+      }
+      break;
+    }
+    case TK_SELECT_COLUMN: {
+      if( pExpr->pLeft->iTable==0 ){
+        pExpr->pLeft->iTable = sqlite3CodeSubselect(pParse, pExpr->pLeft, 0, 0);
+      }
+      return pExpr->pLeft->iTable + pExpr->iColumn;
+    }
+    case TK_IN: {
+      int destIfFalse = sqlite3VdbeMakeLabel(v);
+      int destIfNull = sqlite3VdbeMakeLabel(v);
+      sqlite3VdbeAddOp2(v, OP_Null, 0, target);
+      sqlite3ExprCodeIN(pParse, pExpr, destIfFalse, destIfNull);
+      sqlite3VdbeAddOp2(v, OP_Integer, 1, target);
+      sqlite3VdbeResolveLabel(v, destIfFalse);
+      sqlite3VdbeAddOp2(v, OP_AddImm, target, 0);
+      sqlite3VdbeResolveLabel(v, destIfNull);
+      return target;
+    }
+#endif /* SQLITE_OMIT_SUBQUERY */
+
+
+    /*
+    **    x BETWEEN y AND z
+    **
+    ** This is equivalent to
+    **
+    **    x>=y AND x<=z
+    **
+    ** X is stored in pExpr->pLeft.
+    ** Y is stored in pExpr->pList->a[0].pExpr.
+    ** Z is stored in pExpr->pList->a[1].pExpr.
+    */
+    case TK_BETWEEN: {
+      exprCodeBetween(pParse, pExpr, target, 0, 0);
+      return target;
+    }
+    case TK_SPAN:
+    case TK_COLLATE: 
+    case TK_UPLUS: {
+      return sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);
+    }
+
+    case TK_TRIGGER: {
+      /* If the opcode is TK_TRIGGER, then the expression is a reference
+      ** to a column in the new.* or old.* pseudo-tables available to
+      ** trigger programs. In this case Expr.iTable is set to 1 for the
+      ** new.* pseudo-table, or 0 for the old.* pseudo-table. Expr.iColumn
+      ** is set to the column of the pseudo-table to read, or to -1 to
+      ** read the rowid field.
+      **
+      ** The expression is implemented using an OP_Param opcode. The p1
+      ** parameter is set to 0 for an old.rowid reference, or to (i+1)
+      ** to reference another column of the old.* pseudo-table, where 
+      ** i is the index of the column. For a new.rowid reference, p1 is
+      ** set to (n+1), where n is the number of columns in each pseudo-table.
+      ** For a reference to any other column in the new.* pseudo-table, p1
+      ** is set to (n+2+i), where n and i are as defined previously. For
+      ** example, if the table on which triggers are being fired is
+      ** declared as:
+      **
+      **   CREATE TABLE t1(a, b);
+      **
+      ** Then p1 is interpreted as follows:
+      **
+      **   p1==0   ->    old.rowid     p1==3   ->    new.rowid
+      **   p1==1   ->    old.a         p1==4   ->    new.a
+      **   p1==2   ->    old.b         p1==5   ->    new.b       
+      */
+      Table *pTab = pExpr->pTab;
+      int p1 = pExpr->iTable * (pTab->nCol+1) + 1 + pExpr->iColumn;
+
+      assert( pExpr->iTable==0 || pExpr->iTable==1 );
+      assert( pExpr->iColumn>=-1 && pExpr->iColumn<pTab->nCol );
+      assert( pTab->iPKey<0 || pExpr->iColumn!=pTab->iPKey );
+      assert( p1>=0 && p1<(pTab->nCol*2+2) );
+
+      sqlite3VdbeAddOp2(v, OP_Param, p1, target);
+      VdbeComment((v, "%s.%s -> $%d",
+        (pExpr->iTable ? "new" : "old"),
+        (pExpr->iColumn<0 ? "rowid" : pExpr->pTab->aCol[pExpr->iColumn].zName),
+        target
+      ));
+
+#ifndef SQLITE_OMIT_FLOATING_POINT
+      /* If the column has REAL affinity, it may currently be stored as an
+      ** integer. Use OP_RealAffinity to make sure it is really real.
+      **
+      ** EVIDENCE-OF: R-60985-57662 SQLite will convert the value back to
+      ** floating point when extracting it from the record.  */
+      if( pExpr->iColumn>=0 
+       && pTab->aCol[pExpr->iColumn].affinity==SQLITE_AFF_REAL
+      ){
+        sqlite3VdbeAddOp1(v, OP_RealAffinity, target);
+      }
+#endif
+      break;
+    }
+
+    case TK_VECTOR: {
+      sqlite3ErrorMsg(pParse, "row value misused");
+      break;
+    }
+
+    /*
+    ** Form A:
+    **   CASE x WHEN e1 THEN r1 WHEN e2 THEN r2 ... WHEN eN THEN rN ELSE y END
+    **
+    ** Form B:
+    **   CASE WHEN e1 THEN r1 WHEN e2 THEN r2 ... WHEN eN THEN rN ELSE y END
+    **
+    ** Form A is can be transformed into the equivalent form B as follows:
+    **   CASE WHEN x=e1 THEN r1 WHEN x=e2 THEN r2 ...
+    **        WHEN x=eN THEN rN ELSE y END
+    **
+    ** X (if it exists) is in pExpr->pLeft.
+    ** Y is in the last element of pExpr->x.pList if pExpr->x.pList->nExpr is
+    ** odd.  The Y is also optional.  If the number of elements in x.pList
+    ** is even, then Y is omitted and the "otherwise" result is NULL.
+    ** Ei is in pExpr->pList->a[i*2] and Ri is pExpr->pList->a[i*2+1].
+    **
+    ** The result of the expression is the Ri for the first matching Ei,
+    ** or if there is no matching Ei, the ELSE term Y, or if there is
+    ** no ELSE term, NULL.
+    */
+    default: assert( op==TK_CASE ); {
+      int endLabel;                     /* GOTO label for end of CASE stmt */
+      int nextCase;                     /* GOTO label for next WHEN clause */
+      int nExpr;                        /* 2x number of WHEN terms */
+      int i;                            /* Loop counter */
+      ExprList *pEList;                 /* List of WHEN terms */
+      struct ExprList_item *aListelem;  /* Array of WHEN terms */
+      Expr opCompare;                   /* The X==Ei expression */
+      Expr *pX;                         /* The X expression */
+      Expr *pTest = 0;                  /* X==Ei (form A) or just Ei (form B) */
+      VVA_ONLY( int iCacheLevel = pParse->iCacheLevel; )
+
+      assert( !ExprHasProperty(pExpr, EP_xIsSelect) && pExpr->x.pList );
+      assert(pExpr->x.pList->nExpr > 0);
+      pEList = pExpr->x.pList;
+      aListelem = pEList->a;
+      nExpr = pEList->nExpr;
+      endLabel = sqlite3VdbeMakeLabel(v);
+      if( (pX = pExpr->pLeft)!=0 ){
+        tempX = *pX;
+        testcase( pX->op==TK_COLUMN );
+        exprToRegister(&tempX, exprCodeVector(pParse, &tempX, &regFree1));
+        testcase( regFree1==0 );
+        memset(&opCompare, 0, sizeof(opCompare));
+        opCompare.op = TK_EQ;
+        opCompare.pLeft = &tempX;
+        pTest = &opCompare;
+        /* Ticket b351d95f9cd5ef17e9d9dbae18f5ca8611190001:
+        ** The value in regFree1 might get SCopy-ed into the file result.
+        ** So make sure that the regFree1 register is not reused for other
+        ** purposes and possibly overwritten.  */
+        regFree1 = 0;
+      }
+      for(i=0; i<nExpr-1; i=i+2){
+        sqlite3ExprCachePush(pParse);
+        if( pX ){
+          assert( pTest!=0 );
+          opCompare.pRight = aListelem[i].pExpr;
+        }else{
+          pTest = aListelem[i].pExpr;
+        }
+        nextCase = sqlite3VdbeMakeLabel(v);
+        testcase( pTest->op==TK_COLUMN );
+        sqlite3ExprIfFalse(pParse, pTest, nextCase, SQLITE_JUMPIFNULL);
+        testcase( aListelem[i+1].pExpr->op==TK_COLUMN );
+        sqlite3ExprCode(pParse, aListelem[i+1].pExpr, target);
+        sqlite3VdbeGoto(v, endLabel);
+        sqlite3ExprCachePop(pParse);
+        sqlite3VdbeResolveLabel(v, nextCase);
+      }
+      if( (nExpr&1)!=0 ){
+        sqlite3ExprCachePush(pParse);
+        sqlite3ExprCode(pParse, pEList->a[nExpr-1].pExpr, target);
+        sqlite3ExprCachePop(pParse);
+      }else{
+        sqlite3VdbeAddOp2(v, OP_Null, 0, target);
+      }
+      assert( pParse->db->mallocFailed || pParse->nErr>0 
+           || pParse->iCacheLevel==iCacheLevel );
+      sqlite3VdbeResolveLabel(v, endLabel);
+      break;
+    }
+#ifndef SQLITE_OMIT_TRIGGER
+    case TK_RAISE: {
+      assert( pExpr->affinity==OE_Rollback 
+           || pExpr->affinity==OE_Abort
+           || pExpr->affinity==OE_Fail
+           || pExpr->affinity==OE_Ignore
+      );
+      if( !pParse->pTriggerTab ){
+        sqlite3ErrorMsg(pParse,
+                       "RAISE() may only be used within a trigger-program");
+        return 0;
+      }
+      if( pExpr->affinity==OE_Abort ){
+        sqlite3MayAbort(pParse);
+      }
+      assert( !ExprHasProperty(pExpr, EP_IntValue) );
+      if( pExpr->affinity==OE_Ignore ){
+        sqlite3VdbeAddOp4(
+            v, OP_Halt, SQLITE_OK, OE_Ignore, 0, pExpr->u.zToken,0);
+        VdbeCoverage(v);
+      }else{
+        sqlite3HaltConstraint(pParse, SQLITE_CONSTRAINT_TRIGGER,
+                              pExpr->affinity, pExpr->u.zToken, 0, 0);
+      }
+
+      break;
+    }
+#endif
+  }
+  sqlite3ReleaseTempReg(pParse, regFree1);
+  sqlite3ReleaseTempReg(pParse, regFree2);
+  return inReg;
+}
+
+/*
+** Factor out the code of the given expression to initialization time.
+*/
+SQLITE_PRIVATE void sqlite3ExprCodeAtInit(
+  Parse *pParse,    /* Parsing context */
+  Expr *pExpr,      /* The expression to code when the VDBE initializes */
+  int regDest,      /* Store the value in this register */
+  u8 reusable       /* True if this expression is reusable */
+){
+  ExprList *p;
+  assert( ConstFactorOk(pParse) );
+  p = pParse->pConstExpr;
+  pExpr = sqlite3ExprDup(pParse->db, pExpr, 0);
+  p = sqlite3ExprListAppend(pParse, p, pExpr);
+  if( p ){
+     struct ExprList_item *pItem = &p->a[p->nExpr-1];
+     pItem->u.iConstExprReg = regDest;
+     pItem->reusable = reusable;
+  }
+  pParse->pConstExpr = p;
+}
+
+/*
+** Generate code to evaluate an expression and store the results
+** into a register.  Return the register number where the results
+** are stored.
+**
+** If the register is a temporary register that can be deallocated,
+** then write its number into *pReg.  If the result register is not
+** a temporary, then set *pReg to zero.
+**
+** If pExpr is a constant, then this routine might generate this
+** code to fill the register in the initialization section of the
+** VDBE program, in order to factor it out of the evaluation loop.
+*/
+SQLITE_PRIVATE int sqlite3ExprCodeTemp(Parse *pParse, Expr *pExpr, int *pReg){
+  int r2;
+  pExpr = sqlite3ExprSkipCollate(pExpr);
+  if( ConstFactorOk(pParse)
+   && pExpr->op!=TK_REGISTER
+   && sqlite3ExprIsConstantNotJoin(pExpr)
+  ){
+    ExprList *p = pParse->pConstExpr;
+    int i;
+    *pReg  = 0;
+    if( p ){
+      struct ExprList_item *pItem;
+      for(pItem=p->a, i=p->nExpr; i>0; pItem++, i--){
+        if( pItem->reusable && sqlite3ExprCompare(pItem->pExpr,pExpr,-1)==0 ){
+          return pItem->u.iConstExprReg;
+        }
+      }
+    }
+    r2 = ++pParse->nMem;
+    sqlite3ExprCodeAtInit(pParse, pExpr, r2, 1);
+  }else{
+    int r1 = sqlite3GetTempReg(pParse);
+    r2 = sqlite3ExprCodeTarget(pParse, pExpr, r1);
+    if( r2==r1 ){
+      *pReg = r1;
+    }else{
+      sqlite3ReleaseTempReg(pParse, r1);
+      *pReg = 0;
+    }
+  }
+  return r2;
+}
+
+/*
+** Generate code that will evaluate expression pExpr and store the
+** results in register target.  The results are guaranteed to appear
+** in register target.
+*/
+SQLITE_PRIVATE void sqlite3ExprCode(Parse *pParse, Expr *pExpr, int target){
+  int inReg;
+
+  assert( target>0 && target<=pParse->nMem );
+  if( pExpr && pExpr->op==TK_REGISTER ){
+    sqlite3VdbeAddOp2(pParse->pVdbe, OP_Copy, pExpr->iTable, target);
+  }else{
+    inReg = sqlite3ExprCodeTarget(pParse, pExpr, target);
+    assert( pParse->pVdbe!=0 || pParse->db->mallocFailed );
+    if( inReg!=target && pParse->pVdbe ){
+      sqlite3VdbeAddOp2(pParse->pVdbe, OP_SCopy, inReg, target);
+    }
+  }
+}
+
+/*
+** Make a transient copy of expression pExpr and then code it using
+** sqlite3ExprCode().  This routine works just like sqlite3ExprCode()
+** except that the input expression is guaranteed to be unchanged.
+*/
+SQLITE_PRIVATE void sqlite3ExprCodeCopy(Parse *pParse, Expr *pExpr, int target){
+  sqlite3 *db = pParse->db;
+  pExpr = sqlite3ExprDup(db, pExpr, 0);
+  if( !db->mallocFailed ) sqlite3ExprCode(pParse, pExpr, target);
+  sqlite3ExprDelete(db, pExpr);
+}
+
+/*
+** Generate code that will evaluate expression pExpr and store the
+** results in register target.  The results are guaranteed to appear
+** in register target.  If the expression is constant, then this routine
+** might choose to code the expression at initialization time.
+*/
+SQLITE_PRIVATE void sqlite3ExprCodeFactorable(Parse *pParse, Expr *pExpr, int target){
+  if( pParse->okConstFactor && sqlite3ExprIsConstant(pExpr) ){
+    sqlite3ExprCodeAtInit(pParse, pExpr, target, 0);
+  }else{
+    sqlite3ExprCode(pParse, pExpr, target);
+  }
+}
+
+/*
+** Generate code that evaluates the given expression and puts the result
+** in register target.
+**
+** Also make a copy of the expression results into another "cache" register
+** and modify the expression so that the next time it is evaluated,
+** the result is a copy of the cache register.
+**
+** This routine is used for expressions that are used multiple 
+** times.  They are evaluated once and the results of the expression
+** are reused.
+*/
+SQLITE_PRIVATE void sqlite3ExprCodeAndCache(Parse *pParse, Expr *pExpr, int target){
+  Vdbe *v = pParse->pVdbe;
+  int iMem;
+
+  assert( target>0 );
+  assert( pExpr->op!=TK_REGISTER );
+  sqlite3ExprCode(pParse, pExpr, target);
+  iMem = ++pParse->nMem;
+  sqlite3VdbeAddOp2(v, OP_Copy, target, iMem);
+  exprToRegister(pExpr, iMem);
+}
+
+/*
+** Generate code that pushes the value of every element of the given
+** expression list into a sequence of registers beginning at target.
+**
+** Return the number of elements evaluated.
+**
+** The SQLITE_ECEL_DUP flag prevents the arguments from being
+** filled using OP_SCopy.  OP_Copy must be used instead.
+**
+** The SQLITE_ECEL_FACTOR argument allows constant arguments to be
+** factored out into initialization code.
+**
+** The SQLITE_ECEL_REF flag means that expressions in the list with
+** ExprList.a[].u.x.iOrderByCol>0 have already been evaluated and stored
+** in registers at srcReg, and so the value can be copied from there.
+*/
+SQLITE_PRIVATE int sqlite3ExprCodeExprList(
+  Parse *pParse,     /* Parsing context */
+  ExprList *pList,   /* The expression list to be coded */
+  int target,        /* Where to write results */
+  int srcReg,        /* Source registers if SQLITE_ECEL_REF */
+  u8 flags           /* SQLITE_ECEL_* flags */
+){
+  struct ExprList_item *pItem;
+  int i, j, n;
+  u8 copyOp = (flags & SQLITE_ECEL_DUP) ? OP_Copy : OP_SCopy;
+  Vdbe *v = pParse->pVdbe;
+  assert( pList!=0 );
+  assert( target>0 );
+  assert( pParse->pVdbe!=0 );  /* Never gets this far otherwise */
+  n = pList->nExpr;
+  if( !ConstFactorOk(pParse) ) flags &= ~SQLITE_ECEL_FACTOR;
+  for(pItem=pList->a, i=0; i<n; i++, pItem++){
+    Expr *pExpr = pItem->pExpr;
+    if( (flags & SQLITE_ECEL_REF)!=0 && (j = pList->a[i].u.x.iOrderByCol)>0 ){
+      sqlite3VdbeAddOp2(v, copyOp, j+srcReg-1, target+i);
+    }else if( (flags & SQLITE_ECEL_FACTOR)!=0 && sqlite3ExprIsConstant(pExpr) ){
+      sqlite3ExprCodeAtInit(pParse, pExpr, target+i, 0);
+    }else{
+      int inReg = sqlite3ExprCodeTarget(pParse, pExpr, target+i);
+      if( inReg!=target+i ){
+        VdbeOp *pOp;
+        if( copyOp==OP_Copy
+         && (pOp=sqlite3VdbeGetOp(v, -1))->opcode==OP_Copy
+         && pOp->p1+pOp->p3+1==inReg
+         && pOp->p2+pOp->p3+1==target+i
+        ){
+          pOp->p3++;
+        }else{
+          sqlite3VdbeAddOp2(v, copyOp, inReg, target+i);
+        }
+      }
+    }
+  }
+  return n;
+}
+
+/*
+** Generate code for a BETWEEN operator.
+**
+**    x BETWEEN y AND z
+**
+** The above is equivalent to 
+**
+**    x>=y AND x<=z
+**
+** Code it as such, taking care to do the common subexpression
+** elimination of x.
+**
+** The xJumpIf parameter determines details:
+**
+**    NULL:                   Store the boolean result in reg[dest]
+**    sqlite3ExprIfTrue:      Jump to dest if true
+**    sqlite3ExprIfFalse:     Jump to dest if false
+**
+** The jumpIfNull parameter is ignored if xJumpIf is NULL.
+*/
+static void exprCodeBetween(
+  Parse *pParse,    /* Parsing and code generating context */
+  Expr *pExpr,      /* The BETWEEN expression */
+  int dest,         /* Jump destination or storage location */
+  void (*xJump)(Parse*,Expr*,int,int), /* Action to take */
+  int jumpIfNull    /* Take the jump if the BETWEEN is NULL */
+){
+ Expr exprAnd;     /* The AND operator in  x>=y AND x<=z  */
+  Expr compLeft;    /* The  x>=y  term */
+  Expr compRight;   /* The  x<=z  term */
+  Expr exprX;       /* The  x  subexpression */
+  int regFree1 = 0; /* Temporary use register */
+
+
+  memset(&compLeft, 0, sizeof(Expr));
+  memset(&compRight, 0, sizeof(Expr));
+  memset(&exprAnd, 0, sizeof(Expr));
+
+  assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
+  exprX = *pExpr->pLeft;
+  exprAnd.op = TK_AND;
+  exprAnd.pLeft = &compLeft;
+  exprAnd.pRight = &compRight;
+  compLeft.op = TK_GE;
+  compLeft.pLeft = &exprX;
+  compLeft.pRight = pExpr->x.pList->a[0].pExpr;
+  compRight.op = TK_LE;
+  compRight.pLeft = &exprX;
+  compRight.pRight = pExpr->x.pList->a[1].pExpr;
+  exprToRegister(&exprX, exprCodeVector(pParse, &exprX, &regFree1));
+  if( xJump ){
+    xJump(pParse, &exprAnd, dest, jumpIfNull);
+  }else{
+    exprX.flags |= EP_FromJoin;
+    sqlite3ExprCodeTarget(pParse, &exprAnd, dest);
+  }
+  sqlite3ReleaseTempReg(pParse, regFree1);
+
+  /* Ensure adequate test coverage */
+  testcase( xJump==sqlite3ExprIfTrue  && jumpIfNull==0 && regFree1==0 );
+  testcase( xJump==sqlite3ExprIfTrue  && jumpIfNull==0 && regFree1!=0 );
+  testcase( xJump==sqlite3ExprIfTrue  && jumpIfNull!=0 && regFree1==0 );
+  testcase( xJump==sqlite3ExprIfTrue  && jumpIfNull!=0 && regFree1!=0 );
+  testcase( xJump==sqlite3ExprIfFalse && jumpIfNull==0 && regFree1==0 );
+  testcase( xJump==sqlite3ExprIfFalse && jumpIfNull==0 && regFree1!=0 );
+  testcase( xJump==sqlite3ExprIfFalse && jumpIfNull!=0 && regFree1==0 );
+  testcase( xJump==sqlite3ExprIfFalse && jumpIfNull!=0 && regFree1!=0 );
+  testcase( xJump==0 );
+}
+
+/*
+** Generate code for a boolean expression such that a jump is made
+** to the label "dest" if the expression is true but execution
+** continues straight thru if the expression is false.
+**
+** If the expression evaluates to NULL (neither true nor false), then
+** take the jump if the jumpIfNull flag is SQLITE_JUMPIFNULL.
+**
+** This code depends on the fact that certain token values (ex: TK_EQ)
+** are the same as opcode values (ex: OP_Eq) that implement the corresponding
+** operation.  Special comments in vdbe.c and the mkopcodeh.awk script in
+** the make process cause these values to align.  Assert()s in the code
+** below verify that the numbers are aligned correctly.
+*/
+SQLITE_PRIVATE void sqlite3ExprIfTrue(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
+  Vdbe *v = pParse->pVdbe;
+  int op = 0;
+  int regFree1 = 0;
+  int regFree2 = 0;
+  int r1, r2;
+
+  assert( jumpIfNull==SQLITE_JUMPIFNULL || jumpIfNull==0 );
+  if( NEVER(v==0) )     return;  /* Existence of VDBE checked by caller */
+  if( NEVER(pExpr==0) ) return;  /* No way this can happen */
+  op = pExpr->op;
+  switch( op ){
+    case TK_AND: {
+      int d2 = sqlite3VdbeMakeLabel(v);
+      testcase( jumpIfNull==0 );
+      sqlite3ExprIfFalse(pParse, pExpr->pLeft, d2,jumpIfNull^SQLITE_JUMPIFNULL);
+      sqlite3ExprCachePush(pParse);
+      sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
+      sqlite3VdbeResolveLabel(v, d2);
+      sqlite3ExprCachePop(pParse);
+      break;
+    }
+    case TK_OR: {
+      testcase( jumpIfNull==0 );
+      sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest, jumpIfNull);
+      sqlite3ExprCachePush(pParse);
+      sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
+      sqlite3ExprCachePop(pParse);
+      break;
+    }
+    case TK_NOT: {
+      testcase( jumpIfNull==0 );
+      sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest, jumpIfNull);
+      break;
+    }
+    case TK_IS:
+    case TK_ISNOT:
+      testcase( op==TK_IS );
+      testcase( op==TK_ISNOT );
+      op = (op==TK_IS) ? TK_EQ : TK_NE;
+      jumpIfNull = SQLITE_NULLEQ;
+      /* Fall thru */
+    case TK_LT:
+    case TK_LE:
+    case TK_GT:
+    case TK_GE:
+    case TK_NE:
+    case TK_EQ: {
+      if( sqlite3ExprIsVector(pExpr->pLeft) ) goto default_expr;
+      testcase( jumpIfNull==0 );
+      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
+      r2 = sqlite3ExprCodeTemp(pParse, pExpr->pRight, &regFree2);
+      codeCompare(pParse, pExpr->pLeft, pExpr->pRight, op,
+                  r1, r2, dest, jumpIfNull);
+      assert(TK_LT==OP_Lt); testcase(op==OP_Lt); VdbeCoverageIf(v,op==OP_Lt);
+      assert(TK_LE==OP_Le); testcase(op==OP_Le); VdbeCoverageIf(v,op==OP_Le);
+      assert(TK_GT==OP_Gt); testcase(op==OP_Gt); VdbeCoverageIf(v,op==OP_Gt);
+      assert(TK_GE==OP_Ge); testcase(op==OP_Ge); VdbeCoverageIf(v,op==OP_Ge);
+      assert(TK_EQ==OP_Eq); testcase(op==OP_Eq);
+      VdbeCoverageIf(v, op==OP_Eq && jumpIfNull==SQLITE_NULLEQ);
+      VdbeCoverageIf(v, op==OP_Eq && jumpIfNull!=SQLITE_NULLEQ);
+      assert(TK_NE==OP_Ne); testcase(op==OP_Ne);
+      VdbeCoverageIf(v, op==OP_Ne && jumpIfNull==SQLITE_NULLEQ);
+      VdbeCoverageIf(v, op==OP_Ne && jumpIfNull!=SQLITE_NULLEQ);
+      testcase( regFree1==0 );
+      testcase( regFree2==0 );
+      break;
+    }
+    case TK_ISNULL:
+    case TK_NOTNULL: {
+      assert( TK_ISNULL==OP_IsNull );   testcase( op==TK_ISNULL );
+      assert( TK_NOTNULL==OP_NotNull ); testcase( op==TK_NOTNULL );
+      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
+      sqlite3VdbeAddOp2(v, op, r1, dest);
+      VdbeCoverageIf(v, op==TK_ISNULL);
+      VdbeCoverageIf(v, op==TK_NOTNULL);
+      testcase( regFree1==0 );
+      break;
+    }
+    case TK_BETWEEN: {
+      testcase( jumpIfNull==0 );
+      exprCodeBetween(pParse, pExpr, dest, sqlite3ExprIfTrue, jumpIfNull);
+      break;
+    }
+#ifndef SQLITE_OMIT_SUBQUERY
+    case TK_IN: {
+      int destIfFalse = sqlite3VdbeMakeLabel(v);
+      int destIfNull = jumpIfNull ? dest : destIfFalse;
+      sqlite3ExprCodeIN(pParse, pExpr, destIfFalse, destIfNull);
+      sqlite3VdbeGoto(v, dest);
+      sqlite3VdbeResolveLabel(v, destIfFalse);
+      break;
+    }
+#endif
+    default: {
+    default_expr:
+      if( exprAlwaysTrue(pExpr) ){
+        sqlite3VdbeGoto(v, dest);
+      }else if( exprAlwaysFalse(pExpr) ){
+        /* No-op */
+      }else{
+        r1 = sqlite3ExprCodeTemp(pParse, pExpr, &regFree1);
+        sqlite3VdbeAddOp3(v, OP_If, r1, dest, jumpIfNull!=0);
+        VdbeCoverage(v);
+        testcase( regFree1==0 );
+        testcase( jumpIfNull==0 );
+      }
+      break;
+    }
+  }
+  sqlite3ReleaseTempReg(pParse, regFree1);
+  sqlite3ReleaseTempReg(pParse, regFree2);  
+}
+
+/*
+** Generate code for a boolean expression such that a jump is made
+** to the label "dest" if the expression is false but execution
+** continues straight thru if the expression is true.
+**
+** If the expression evaluates to NULL (neither true nor false) then
+** jump if jumpIfNull is SQLITE_JUMPIFNULL or fall through if jumpIfNull
+** is 0.
+*/
+SQLITE_PRIVATE void sqlite3ExprIfFalse(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
+  Vdbe *v = pParse->pVdbe;
+  int op = 0;
+  int regFree1 = 0;
+  int regFree2 = 0;
+  int r1, r2;
+
+  assert( jumpIfNull==SQLITE_JUMPIFNULL || jumpIfNull==0 );
+  if( NEVER(v==0) ) return; /* Existence of VDBE checked by caller */
+  if( pExpr==0 )    return;
+
+  /* The value of pExpr->op and op are related as follows:
+  **
+  **       pExpr->op            op
+  **       ---------          ----------
+  **       TK_ISNULL          OP_NotNull
+  **       TK_NOTNULL         OP_IsNull
+  **       TK_NE              OP_Eq
+  **       TK_EQ              OP_Ne
+  **       TK_GT              OP_Le
+  **       TK_LE              OP_Gt
+  **       TK_GE              OP_Lt
+  **       TK_LT              OP_Ge
+  **
+  ** For other values of pExpr->op, op is undefined and unused.
+  ** The value of TK_ and OP_ constants are arranged such that we
+  ** can compute the mapping above using the following expression.
+  ** Assert()s verify that the computation is correct.
+  */
+  op = ((pExpr->op+(TK_ISNULL&1))^1)-(TK_ISNULL&1);
+
+  /* Verify correct alignment of TK_ and OP_ constants
+  */
+  assert( pExpr->op!=TK_ISNULL || op==OP_NotNull );
+  assert( pExpr->op!=TK_NOTNULL || op==OP_IsNull );
+  assert( pExpr->op!=TK_NE || op==OP_Eq );
+  assert( pExpr->op!=TK_EQ || op==OP_Ne );
+  assert( pExpr->op!=TK_LT || op==OP_Ge );
+  assert( pExpr->op!=TK_LE || op==OP_Gt );
+  assert( pExpr->op!=TK_GT || op==OP_Le );
+  assert( pExpr->op!=TK_GE || op==OP_Lt );
+
+  switch( pExpr->op ){
+    case TK_AND: {
+      testcase( jumpIfNull==0 );
+      sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest, jumpIfNull);
+      sqlite3ExprCachePush(pParse);
+      sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
+      sqlite3ExprCachePop(pParse);
+      break;
+    }
+    case TK_OR: {
+      int d2 = sqlite3VdbeMakeLabel(v);
+      testcase( jumpIfNull==0 );
+      sqlite3ExprIfTrue(pParse, pExpr->pLeft, d2, jumpIfNull^SQLITE_JUMPIFNULL);
+      sqlite3ExprCachePush(pParse);
+      sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
+      sqlite3VdbeResolveLabel(v, d2);
+      sqlite3ExprCachePop(pParse);
+      break;
+    }
+    case TK_NOT: {
+      testcase( jumpIfNull==0 );
+      sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest, jumpIfNull);
+      break;
+    }
+    case TK_IS:
+    case TK_ISNOT:
+      testcase( pExpr->op==TK_IS );
+      testcase( pExpr->op==TK_ISNOT );
+      op = (pExpr->op==TK_IS) ? TK_NE : TK_EQ;
+      jumpIfNull = SQLITE_NULLEQ;
+      /* Fall thru */
+    case TK_LT:
+    case TK_LE:
+    case TK_GT:
+    case TK_GE:
+    case TK_NE:
+    case TK_EQ: {
+      if( sqlite3ExprIsVector(pExpr->pLeft) ) goto default_expr;
+      testcase( jumpIfNull==0 );
+      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
+      r2 = sqlite3ExprCodeTemp(pParse, pExpr->pRight, &regFree2);
+      codeCompare(pParse, pExpr->pLeft, pExpr->pRight, op,
+                  r1, r2, dest, jumpIfNull);
+      assert(TK_LT==OP_Lt); testcase(op==OP_Lt); VdbeCoverageIf(v,op==OP_Lt);
+      assert(TK_LE==OP_Le); testcase(op==OP_Le); VdbeCoverageIf(v,op==OP_Le);
+      assert(TK_GT==OP_Gt); testcase(op==OP_Gt); VdbeCoverageIf(v,op==OP_Gt);
+      assert(TK_GE==OP_Ge); testcase(op==OP_Ge); VdbeCoverageIf(v,op==OP_Ge);
+      assert(TK_EQ==OP_Eq); testcase(op==OP_Eq);
+      VdbeCoverageIf(v, op==OP_Eq && jumpIfNull!=SQLITE_NULLEQ);
+      VdbeCoverageIf(v, op==OP_Eq && jumpIfNull==SQLITE_NULLEQ);
+      assert(TK_NE==OP_Ne); testcase(op==OP_Ne);
+      VdbeCoverageIf(v, op==OP_Ne && jumpIfNull!=SQLITE_NULLEQ);
+      VdbeCoverageIf(v, op==OP_Ne && jumpIfNull==SQLITE_NULLEQ);
+      testcase( regFree1==0 );
+      testcase( regFree2==0 );
+      break;
+    }
+    case TK_ISNULL:
+    case TK_NOTNULL: {
+      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
+      sqlite3VdbeAddOp2(v, op, r1, dest);
+      testcase( op==TK_ISNULL );   VdbeCoverageIf(v, op==TK_ISNULL);
+      testcase( op==TK_NOTNULL );  VdbeCoverageIf(v, op==TK_NOTNULL);
+      testcase( regFree1==0 );
+      break;
+    }
+    case TK_BETWEEN: {
+      testcase( jumpIfNull==0 );
+      exprCodeBetween(pParse, pExpr, dest, sqlite3ExprIfFalse, jumpIfNull);
+      break;
+    }
+#ifndef SQLITE_OMIT_SUBQUERY
+    case TK_IN: {
+      if( jumpIfNull ){
+        sqlite3ExprCodeIN(pParse, pExpr, dest, dest);
+      }else{
+        int destIfNull = sqlite3VdbeMakeLabel(v);
+        sqlite3ExprCodeIN(pParse, pExpr, dest, destIfNull);
+        sqlite3VdbeResolveLabel(v, destIfNull);
+      }
+      break;
+    }
+#endif
+    default: {
+    default_expr: 
+      if( exprAlwaysFalse(pExpr) ){
+        sqlite3VdbeGoto(v, dest);
+      }else if( exprAlwaysTrue(pExpr) ){
+        /* no-op */
+      }else{
+        r1 = sqlite3ExprCodeTemp(pParse, pExpr, &regFree1);
+        sqlite3VdbeAddOp3(v, OP_IfNot, r1, dest, jumpIfNull!=0);
+        VdbeCoverage(v);
+        testcase( regFree1==0 );
+        testcase( jumpIfNull==0 );
+      }
+      break;
+    }
+  }
+  sqlite3ReleaseTempReg(pParse, regFree1);
+  sqlite3ReleaseTempReg(pParse, regFree2);
+}
+
+/*
+** Like sqlite3ExprIfFalse() except that a copy is made of pExpr before
+** code generation, and that copy is deleted after code generation. This
+** ensures that the original pExpr is unchanged.
+*/
+SQLITE_PRIVATE void sqlite3ExprIfFalseDup(Parse *pParse, Expr *pExpr, int dest,int jumpIfNull){
+  sqlite3 *db = pParse->db;
+  Expr *pCopy = sqlite3ExprDup(db, pExpr, 0);
+  if( db->mallocFailed==0 ){
+    sqlite3ExprIfFalse(pParse, pCopy, dest, jumpIfNull);
+  }
+  sqlite3ExprDelete(db, pCopy);
+}
+
+
+/*
+** Do a deep comparison of two expression trees.  Return 0 if the two
+** expressions are completely identical.  Return 1 if they differ only
+** by a COLLATE operator at the top level.  Return 2 if there are differences
+** other than the top-level COLLATE operator.
+**
+** If any subelement of pB has Expr.iTable==(-1) then it is allowed
+** to compare equal to an equivalent element in pA with Expr.iTable==iTab.
+**
+** The pA side might be using TK_REGISTER.  If that is the case and pB is
+** not using TK_REGISTER but is otherwise equivalent, then still return 0.
+**
+** Sometimes this routine will return 2 even if the two expressions
+** really are equivalent.  If we cannot prove that the expressions are
+** identical, we return 2 just to be safe.  So if this routine
+** returns 2, then you do not really know for certain if the two
+** expressions are the same.  But if you get a 0 or 1 return, then you
+** can be sure the expressions are the same.  In the places where
+** this routine is used, it does not hurt to get an extra 2 - that
+** just might result in some slightly slower code.  But returning
+** an incorrect 0 or 1 could lead to a malfunction.
+*/
+SQLITE_PRIVATE int sqlite3ExprCompare(Expr *pA, Expr *pB, int iTab){
+  u32 combinedFlags;
+  if( pA==0 || pB==0 ){
+    return pB==pA ? 0 : 2;
+  }
+  combinedFlags = pA->flags | pB->flags;
+  if( combinedFlags & EP_IntValue ){
+    if( (pA->flags&pB->flags&EP_IntValue)!=0 && pA->u.iValue==pB->u.iValue ){
+      return 0;
+    }
+    return 2;
+  }
+  if( pA->op!=pB->op ){
+    if( pA->op==TK_COLLATE && sqlite3ExprCompare(pA->pLeft, pB, iTab)<2 ){
+      return 1;
+    }
+    if( pB->op==TK_COLLATE && sqlite3ExprCompare(pA, pB->pLeft, iTab)<2 ){
+      return 1;
+    }
+    return 2;
+  }
+  if( pA->op!=TK_COLUMN && pA->op!=TK_AGG_COLUMN && pA->u.zToken ){
+    if( pA->op==TK_FUNCTION ){
+      if( sqlite3StrICmp(pA->u.zToken,pB->u.zToken)!=0 ) return 2;
+    }else if( strcmp(pA->u.zToken,pB->u.zToken)!=0 ){
+      return pA->op==TK_COLLATE ? 1 : 2;
+    }
+  }
+  if( (pA->flags & EP_Distinct)!=(pB->flags & EP_Distinct) ) return 2;
+  if( ALWAYS((combinedFlags & EP_TokenOnly)==0) ){
+    if( combinedFlags & EP_xIsSelect ) return 2;
+    if( sqlite3ExprCompare(pA->pLeft, pB->pLeft, iTab) ) return 2;
+    if( sqlite3ExprCompare(pA->pRight, pB->pRight, iTab) ) return 2;
+    if( sqlite3ExprListCompare(pA->x.pList, pB->x.pList, iTab) ) return 2;
+    if( ALWAYS((combinedFlags & EP_Reduced)==0) && pA->op!=TK_STRING ){
+      if( pA->iColumn!=pB->iColumn ) return 2;
+      if( pA->iTable!=pB->iTable 
+       && (pA->iTable!=iTab || NEVER(pB->iTable>=0)) ) return 2;
+    }
+  }
+  return 0;
+}
+
+/*
+** Compare two ExprList objects.  Return 0 if they are identical and 
+** non-zero if they differ in any way.
+**
+** If any subelement of pB has Expr.iTable==(-1) then it is allowed
+** to compare equal to an equivalent element in pA with Expr.iTable==iTab.
+**
+** This routine might return non-zero for equivalent ExprLists.  The
+** only consequence will be disabled optimizations.  But this routine
+** must never return 0 if the two ExprList objects are different, or
+** a malfunction will result.
+**
+** Two NULL pointers are considered to be the same.  But a NULL pointer
+** always differs from a non-NULL pointer.
+*/
+SQLITE_PRIVATE int sqlite3ExprListCompare(ExprList *pA, ExprList *pB, int iTab){
+  int i;
+  if( pA==0 && pB==0 ) return 0;
+  if( pA==0 || pB==0 ) return 1;
+  if( pA->nExpr!=pB->nExpr ) return 1;
+  for(i=0; i<pA->nExpr; i++){
+    Expr *pExprA = pA->a[i].pExpr;
+    Expr *pExprB = pB->a[i].pExpr;
+    if( pA->a[i].sortOrder!=pB->a[i].sortOrder ) return 1;
+    if( sqlite3ExprCompare(pExprA, pExprB, iTab) ) return 1;
+  }
+  return 0;
+}
+
+/*
+** Return true if we can prove the pE2 will always be true if pE1 is
+** true.  Return false if we cannot complete the proof or if pE2 might
+** be false.  Examples:
+**
+**     pE1: x==5       pE2: x==5             Result: true
+**     pE1: x>0        pE2: x==5             Result: false
+**     pE1: x=21       pE2: x=21 OR y=43     Result: true
+**     pE1: x!=123     pE2: x IS NOT NULL    Result: true
+**     pE1: x!=?1      pE2: x IS NOT NULL    Result: true
+**     pE1: x IS NULL  pE2: x IS NOT NULL    Result: false
+**     pE1: x IS ?2    pE2: x IS NOT NULL    Reuslt: false
+**
+** When comparing TK_COLUMN nodes between pE1 and pE2, if pE2 has
+** Expr.iTable<0 then assume a table number given by iTab.
+**
+** When in doubt, return false.  Returning true might give a performance
+** improvement.  Returning false might cause a performance reduction, but
+** it will always give the correct answer and is hence always safe.
+*/
+SQLITE_PRIVATE int sqlite3ExprImpliesExpr(Expr *pE1, Expr *pE2, int iTab){
+  if( sqlite3ExprCompare(pE1, pE2, iTab)==0 ){
+    return 1;
+  }
+  if( pE2->op==TK_OR
+   && (sqlite3ExprImpliesExpr(pE1, pE2->pLeft, iTab)
+             || sqlite3ExprImpliesExpr(pE1, pE2->pRight, iTab) )
+  ){
+    return 1;
+  }
+  if( pE2->op==TK_NOTNULL
+   && sqlite3ExprCompare(pE1->pLeft, pE2->pLeft, iTab)==0
+   && (pE1->op!=TK_ISNULL && pE1->op!=TK_IS)
+  ){
+    return 1;
+  }
+  return 0;
+}
+
+/*
+** An instance of the following structure is used by the tree walker
+** to determine if an expression can be evaluated by reference to the
+** index only, without having to do a search for the corresponding
+** table entry.  The IdxCover.pIdx field is the index.  IdxCover.iCur
+** is the cursor for the table.
+*/
+struct IdxCover {
+  Index *pIdx;     /* The index to be tested for coverage */
+  int iCur;        /* Cursor number for the table corresponding to the index */
+};
+
+/*
+** Check to see if there are references to columns in table 
+** pWalker->u.pIdxCover->iCur can be satisfied using the index
+** pWalker->u.pIdxCover->pIdx.
+*/
+static int exprIdxCover(Walker *pWalker, Expr *pExpr){
+  if( pExpr->op==TK_COLUMN
+   && pExpr->iTable==pWalker->u.pIdxCover->iCur
+   && sqlite3ColumnOfIndex(pWalker->u.pIdxCover->pIdx, pExpr->iColumn)<0
+  ){
+    pWalker->eCode = 1;
+    return WRC_Abort;
+  }
+  return WRC_Continue;
+}
+
+/*
+** Determine if an index pIdx on table with cursor iCur contains will
+** the expression pExpr.  Return true if the index does cover the
+** expression and false if the pExpr expression references table columns
+** that are not found in the index pIdx.
+**
+** An index covering an expression means that the expression can be
+** evaluated using only the index and without having to lookup the
+** corresponding table entry.
+*/
+SQLITE_PRIVATE int sqlite3ExprCoveredByIndex(
+  Expr *pExpr,        /* The index to be tested */
+  int iCur,           /* The cursor number for the corresponding table */
+  Index *pIdx         /* The index that might be used for coverage */
+){
+  Walker w;
+  struct IdxCover xcov;
+  memset(&w, 0, sizeof(w));
+  xcov.iCur = iCur;
+  xcov.pIdx = pIdx;
+  w.xExprCallback = exprIdxCover;
+  w.u.pIdxCover = &xcov;
+  sqlite3WalkExpr(&w, pExpr);
+  return !w.eCode;
+}
+
+
+/*
+** An instance of the following structure is used by the tree walker
+** to count references to table columns in the arguments of an 
+** aggregate function, in order to implement the
+** sqlite3FunctionThisSrc() routine.
+*/
+struct SrcCount {
+  SrcList *pSrc;   /* One particular FROM clause in a nested query */
+  int nThis;       /* Number of references to columns in pSrcList */
+  int nOther;      /* Number of references to columns in other FROM clauses */
+};
+
+/*
+** Count the number of references to columns.
+*/
+static int exprSrcCount(Walker *pWalker, Expr *pExpr){
+  /* The NEVER() on the second term is because sqlite3FunctionUsesThisSrc()
+  ** is always called before sqlite3ExprAnalyzeAggregates() and so the
+  ** TK_COLUMNs have not yet been converted into TK_AGG_COLUMN.  If
+  ** sqlite3FunctionUsesThisSrc() is used differently in the future, the
+  ** NEVER() will need to be removed. */
+  if( pExpr->op==TK_COLUMN || NEVER(pExpr->op==TK_AGG_COLUMN) ){
+    int i;
+    struct SrcCount *p = pWalker->u.pSrcCount;
+    SrcList *pSrc = p->pSrc;
+    int nSrc = pSrc ? pSrc->nSrc : 0;
+    for(i=0; i<nSrc; i++){
+      if( pExpr->iTable==pSrc->a[i].iCursor ) break;
+    }
+    if( i<nSrc ){
+      p->nThis++;
+    }else{
+      p->nOther++;
+    }
+  }
+  return WRC_Continue;
+}
+
+/*
+** Determine if any of the arguments to the pExpr Function reference
+** pSrcList.  Return true if they do.  Also return true if the function
+** has no arguments or has only constant arguments.  Return false if pExpr
+** references columns but not columns of tables found in pSrcList.
+*/
+SQLITE_PRIVATE int sqlite3FunctionUsesThisSrc(Expr *pExpr, SrcList *pSrcList){
+  Walker w;
+  struct SrcCount cnt;
+  assert( pExpr->op==TK_AGG_FUNCTION );
+  memset(&w, 0, sizeof(w));
+  w.xExprCallback = exprSrcCount;
+  w.u.pSrcCount = &cnt;
+  cnt.pSrc = pSrcList;
+  cnt.nThis = 0;
+  cnt.nOther = 0;
+  sqlite3WalkExprList(&w, pExpr->x.pList);
+  return cnt.nThis>0 || cnt.nOther==0;
+}
+
+/*
+** Add a new element to the pAggInfo->aCol[] array.  Return the index of
+** the new element.  Return a negative number if malloc fails.
+*/
+static int addAggInfoColumn(sqlite3 *db, AggInfo *pInfo){
+  int i;
+  pInfo->aCol = sqlite3ArrayAllocate(
+       db,
+       pInfo->aCol,
+       sizeof(pInfo->aCol[0]),
+       &pInfo->nColumn,
+       &i
+  );
+  return i;
+}    
+
+/*
+** Add a new element to the pAggInfo->aFunc[] array.  Return the index of
+** the new element.  Return a negative number if malloc fails.
+*/
+static int addAggInfoFunc(sqlite3 *db, AggInfo *pInfo){
+  int i;
+  pInfo->aFunc = sqlite3ArrayAllocate(
+       db, 
+       pInfo->aFunc,
+       sizeof(pInfo->aFunc[0]),
+       &pInfo->nFunc,
+       &i
+  );
+  return i;
+}    
+
+/*
+** This is the xExprCallback for a tree walker.  It is used to
+** implement sqlite3ExprAnalyzeAggregates().  See sqlite3ExprAnalyzeAggregates
+** for additional information.
+*/
+static int analyzeAggregate(Walker *pWalker, Expr *pExpr){
+  int i;
+  NameContext *pNC = pWalker->u.pNC;
+  Parse *pParse = pNC->pParse;
+  SrcList *pSrcList = pNC->pSrcList;
+  AggInfo *pAggInfo = pNC->pAggInfo;
+
+  switch( pExpr->op ){
+    case TK_AGG_COLUMN:
+    case TK_COLUMN: {
+      testcase( pExpr->op==TK_AGG_COLUMN );
+      testcase( pExpr->op==TK_COLUMN );
+      /* Check to see if the column is in one of the tables in the FROM
+      ** clause of the aggregate query */
+      if( ALWAYS(pSrcList!=0) ){
+        struct SrcList_item *pItem = pSrcList->a;
+        for(i=0; i<pSrcList->nSrc; i++, pItem++){
+          struct AggInfo_col *pCol;
+          assert( !ExprHasProperty(pExpr, EP_TokenOnly|EP_Reduced) );
+          if( pExpr->iTable==pItem->iCursor ){
+            /* If we reach this point, it means that pExpr refers to a table
+            ** that is in the FROM clause of the aggregate query.  
+            **
+            ** Make an entry for the column in pAggInfo->aCol[] if there
+            ** is not an entry there already.
+            */
+            int k;
+            pCol = pAggInfo->aCol;
+            for(k=0; k<pAggInfo->nColumn; k++, pCol++){
+              if( pCol->iTable==pExpr->iTable &&
+                  pCol->iColumn==pExpr->iColumn ){
+                break;
+              }
+            }
+            if( (k>=pAggInfo->nColumn)
+             && (k = addAggInfoColumn(pParse->db, pAggInfo))>=0 
+            ){
+              pCol = &pAggInfo->aCol[k];
+              pCol->pTab = pExpr->pTab;
+              pCol->iTable = pExpr->iTable;
+              pCol->iColumn = pExpr->iColumn;
+              pCol->iMem = ++pParse->nMem;
+              pCol->iSorterColumn = -1;
+              pCol->pExpr = pExpr;
+              if( pAggInfo->pGroupBy ){
+                int j, n;
+                ExprList *pGB = pAggInfo->pGroupBy;
+                struct ExprList_item *pTerm = pGB->a;
+                n = pGB->nExpr;
+                for(j=0; j<n; j++, pTerm++){
+                  Expr *pE = pTerm->pExpr;
+                  if( pE->op==TK_COLUMN && pE->iTable==pExpr->iTable &&
+                      pE->iColumn==pExpr->iColumn ){
+                    pCol->iSorterColumn = j;
+                    break;
+                  }
+                }
+              }
+              if( pCol->iSorterColumn<0 ){
+                pCol->iSorterColumn = pAggInfo->nSortingColumn++;
+              }
+            }
+            /* There is now an entry for pExpr in pAggInfo->aCol[] (either
+            ** because it was there before or because we just created it).
+            ** Convert the pExpr to be a TK_AGG_COLUMN referring to that
+            ** pAggInfo->aCol[] entry.
+            */
+            ExprSetVVAProperty(pExpr, EP_NoReduce);
+            pExpr->pAggInfo = pAggInfo;
+            pExpr->op = TK_AGG_COLUMN;
+            pExpr->iAgg = (i16)k;
+            break;
+          } /* endif pExpr->iTable==pItem->iCursor */
+        } /* end loop over pSrcList */
+      }
+      return WRC_Prune;
+    }
+    case TK_AGG_FUNCTION: {
+      if( (pNC->ncFlags & NC_InAggFunc)==0
+       && pWalker->walkerDepth==pExpr->op2
+      ){
+        /* Check to see if pExpr is a duplicate of another aggregate 
+        ** function that is already in the pAggInfo structure
+        */
+        struct AggInfo_func *pItem = pAggInfo->aFunc;
+        for(i=0; i<pAggInfo->nFunc; i++, pItem++){
+          if( sqlite3ExprCompare(pItem->pExpr, pExpr, -1)==0 ){
+            break;
+          }
+        }
+        if( i>=pAggInfo->nFunc ){
+          /* pExpr is original.  Make a new entry in pAggInfo->aFunc[]
+          */
+          u8 enc = ENC(pParse->db);
+          i = addAggInfoFunc(pParse->db, pAggInfo);
+          if( i>=0 ){
+            assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
+            pItem = &pAggInfo->aFunc[i];
+            pItem->pExpr = pExpr;
+            pItem->iMem = ++pParse->nMem;
+            assert( !ExprHasProperty(pExpr, EP_IntValue) );
+            pItem->pFunc = sqlite3FindFunction(pParse->db,
+                   pExpr->u.zToken, 
+                   pExpr->x.pList ? pExpr->x.pList->nExpr : 0, enc, 0);
+            if( pExpr->flags & EP_Distinct ){
+              pItem->iDistinct = pParse->nTab++;
+            }else{
+              pItem->iDistinct = -1;
+            }
+          }
+        }
+        /* Make pExpr point to the appropriate pAggInfo->aFunc[] entry
+        */
+        assert( !ExprHasProperty(pExpr, EP_TokenOnly|EP_Reduced) );
+        ExprSetVVAProperty(pExpr, EP_NoReduce);
+        pExpr->iAgg = (i16)i;
+        pExpr->pAggInfo = pAggInfo;
+        return WRC_Prune;
+      }else{
+        return WRC_Continue;
+      }
+    }
+  }
+  return WRC_Continue;
+}
+static int analyzeAggregatesInSelect(Walker *pWalker, Select *pSelect){
+  UNUSED_PARAMETER(pWalker);
+  UNUSED_PARAMETER(pSelect);
+  return WRC_Continue;
+}
+
+/*
+** Analyze the pExpr expression looking for aggregate functions and
+** for variables that need to be added to AggInfo object that pNC->pAggInfo
+** points to.  Additional entries are made on the AggInfo object as
+** necessary.
+**
+** This routine should only be called after the expression has been
+** analyzed by sqlite3ResolveExprNames().
+*/
+SQLITE_PRIVATE void sqlite3ExprAnalyzeAggregates(NameContext *pNC, Expr *pExpr){
+  Walker w;
+  memset(&w, 0, sizeof(w));
+  w.xExprCallback = analyzeAggregate;
+  w.xSelectCallback = analyzeAggregatesInSelect;
+  w.u.pNC = pNC;
+  assert( pNC->pSrcList!=0 );
+  sqlite3WalkExpr(&w, pExpr);
+}
+
+/*
+** Call sqlite3ExprAnalyzeAggregates() for every expression in an
+** expression list.  Return the number of errors.
+**
+** If an error is found, the analysis is cut short.
+*/
+SQLITE_PRIVATE void sqlite3ExprAnalyzeAggList(NameContext *pNC, ExprList *pList){
+  struct ExprList_item *pItem;
+  int i;
+  if( pList ){
+    for(pItem=pList->a, i=0; i<pList->nExpr; i++, pItem++){
+      sqlite3ExprAnalyzeAggregates(pNC, pItem->pExpr);
+    }
+  }
+}
+
+/*
+** Allocate a single new register for use to hold some intermediate result.
+*/
+SQLITE_PRIVATE int sqlite3GetTempReg(Parse *pParse){
+  if( pParse->nTempReg==0 ){
+    return ++pParse->nMem;
+  }
+  return pParse->aTempReg[--pParse->nTempReg];
+}
+
+/*
+** Deallocate a register, making available for reuse for some other
+** purpose.
+**
+** If a register is currently being used by the column cache, then
+** the deallocation is deferred until the column cache line that uses
+** the register becomes stale.
+*/
+SQLITE_PRIVATE void sqlite3ReleaseTempReg(Parse *pParse, int iReg){
+  if( iReg && pParse->nTempReg<ArraySize(pParse->aTempReg) ){
+    int i;
+    struct yColCache *p;
+    for(i=0, p=pParse->aColCache; i<pParse->nColCache; i++, p++){
+      if( p->iReg==iReg ){
+        p->tempReg = 1;
+        return;
+      }
+    }
+    pParse->aTempReg[pParse->nTempReg++] = iReg;
+  }
+}
+
+/*
+** Allocate or deallocate a block of nReg consecutive registers.
+*/
+SQLITE_PRIVATE int sqlite3GetTempRange(Parse *pParse, int nReg){
+  int i, n;
+  if( nReg==1 ) return sqlite3GetTempReg(pParse);
+  i = pParse->iRangeReg;
+  n = pParse->nRangeReg;
+  if( nReg<=n ){
+    assert( !usedAsColumnCache(pParse, i, i+n-1) );
+    pParse->iRangeReg += nReg;
+    pParse->nRangeReg -= nReg;
+  }else{
+    i = pParse->nMem+1;
+    pParse->nMem += nReg;
+  }
+  return i;
+}
+SQLITE_PRIVATE void sqlite3ReleaseTempRange(Parse *pParse, int iReg, int nReg){
+  if( nReg==1 ){
+    sqlite3ReleaseTempReg(pParse, iReg);
+    return;
+  }
+  sqlite3ExprCacheRemove(pParse, iReg, nReg);
+  if( nReg>pParse->nRangeReg ){
+    pParse->nRangeReg = nReg;
+    pParse->iRangeReg = iReg;
+  }
+}
+
+/*
+** Mark all temporary registers as being unavailable for reuse.
+*/
+SQLITE_PRIVATE void sqlite3ClearTempRegCache(Parse *pParse){
+  pParse->nTempReg = 0;
+  pParse->nRangeReg = 0;
+}
+
+/*
+** Validate that no temporary register falls within the range of
+** iFirst..iLast, inclusive.  This routine is only call from within assert()
+** statements.
+*/
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE int sqlite3NoTempsInRange(Parse *pParse, int iFirst, int iLast){
+  int i;
+  if( pParse->nRangeReg>0
+   && pParse->iRangeReg+pParse->nRangeReg<iLast
+   && pParse->iRangeReg>=iFirst
+  ){
+     return 0;
+  }
+  for(i=0; i<pParse->nTempReg; i++){
+    if( pParse->aTempReg[i]>=iFirst && pParse->aTempReg[i]<=iLast ){
+      return 0;
+    }
+  }
+  return 1;
+}
+#endif /* SQLITE_DEBUG */
+
+/************** End of expr.c ************************************************/
+/************** Begin file alter.c *******************************************/
+/*
+** 2005 February 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains C code routines that used to generate VDBE code
+** that implements the ALTER TABLE command.
+*/
+/* #include "sqliteInt.h" */
+
+/*
+** The code in this file only exists if we are not omitting the
+** ALTER TABLE logic from the build.
+*/
+#ifndef SQLITE_OMIT_ALTERTABLE
+
+
+/*
+** This function is used by SQL generated to implement the 
+** ALTER TABLE command. The first argument is the text of a CREATE TABLE or
+** CREATE INDEX command. The second is a table name. The table name in 
+** the CREATE TABLE or CREATE INDEX statement is replaced with the third
+** argument and the result returned. Examples:
+**
+** sqlite_rename_table('CREATE TABLE abc(a, b, c)', 'def')
+**     -> 'CREATE TABLE def(a, b, c)'
+**
+** sqlite_rename_table('CREATE INDEX i ON abc(a)', 'def')
+**     -> 'CREATE INDEX i ON def(a, b, c)'
+*/
+static void renameTableFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **argv
+){
+  unsigned char const *zSql = sqlite3_value_text(argv[0]);
+  unsigned char const *zTableName = sqlite3_value_text(argv[1]);
+
+  int token;
+  Token tname;
+  unsigned char const *zCsr = zSql;
+  int len = 0;
+  char *zRet;
+
+  sqlite3 *db = sqlite3_context_db_handle(context);
+
+  UNUSED_PARAMETER(NotUsed);
+
+  /* The principle used to locate the table name in the CREATE TABLE 
+  ** statement is that the table name is the first non-space token that
+  ** is immediately followed by a TK_LP or TK_USING token.
+  */
+  if( zSql ){
+    do {
+      if( !*zCsr ){
+        /* Ran out of input before finding an opening bracket. Return NULL. */
+        return;
+      }
+
+      /* Store the token that zCsr points to in tname. */
+      tname.z = (char*)zCsr;
+      tname.n = len;
+
+      /* Advance zCsr to the next token. Store that token type in 'token',
+      ** and its length in 'len' (to be used next iteration of this loop).
+      */
+      do {
+        zCsr += len;
+        len = sqlite3GetToken(zCsr, &token);
+      } while( token==TK_SPACE );
+      assert( len>0 );
+    } while( token!=TK_LP && token!=TK_USING );
+
+    zRet = sqlite3MPrintf(db, "%.*s\"%w\"%s", (int)(((u8*)tname.z) - zSql),
+       zSql, zTableName, tname.z+tname.n);
+    sqlite3_result_text(context, zRet, -1, SQLITE_DYNAMIC);
+  }
+}
+
+/*
+** This C function implements an SQL user function that is used by SQL code
+** generated by the ALTER TABLE ... RENAME command to modify the definition
+** of any foreign key constraints that use the table being renamed as the 
+** parent table. It is passed three arguments:
+**
+**   1) The complete text of the CREATE TABLE statement being modified,
+**   2) The old name of the table being renamed, and
+**   3) The new name of the table being renamed.
+**
+** It returns the new CREATE TABLE statement. For example:
+**
+**   sqlite_rename_parent('CREATE TABLE t1(a REFERENCES t2)', 't2', 't3')
+**       -> 'CREATE TABLE t1(a REFERENCES t3)'
+*/
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+static void renameParentFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **argv
+){
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  char *zOutput = 0;
+  char *zResult;
+  unsigned char const *zInput = sqlite3_value_text(argv[0]);
+  unsigned char const *zOld = sqlite3_value_text(argv[1]);
+  unsigned char const *zNew = sqlite3_value_text(argv[2]);
+
+  unsigned const char *z;         /* Pointer to token */
+  int n;                          /* Length of token z */
+  int token;                      /* Type of token */
+
+  UNUSED_PARAMETER(NotUsed);
+  if( zInput==0 || zOld==0 ) return;
+  for(z=zInput; *z; z=z+n){
+    n = sqlite3GetToken(z, &token);
+    if( token==TK_REFERENCES ){
+      char *zParent;
+      do {
+        z += n;
+        n = sqlite3GetToken(z, &token);
+      }while( token==TK_SPACE );
+
+      if( token==TK_ILLEGAL ) break;
+      zParent = sqlite3DbStrNDup(db, (const char *)z, n);
+      if( zParent==0 ) break;
+      sqlite3Dequote(zParent);
+      if( 0==sqlite3StrICmp((const char *)zOld, zParent) ){
+        char *zOut = sqlite3MPrintf(db, "%s%.*s\"%w\"", 
+            (zOutput?zOutput:""), (int)(z-zInput), zInput, (const char *)zNew
+        );
+        sqlite3DbFree(db, zOutput);
+        zOutput = zOut;
+        zInput = &z[n];
+      }
+      sqlite3DbFree(db, zParent);
+    }
+  }
+
+  zResult = sqlite3MPrintf(db, "%s%s", (zOutput?zOutput:""), zInput), 
+  sqlite3_result_text(context, zResult, -1, SQLITE_DYNAMIC);
+  sqlite3DbFree(db, zOutput);
+}
+#endif
+
+#ifndef SQLITE_OMIT_TRIGGER
+/* This function is used by SQL generated to implement the
+** ALTER TABLE command. The first argument is the text of a CREATE TRIGGER 
+** statement. The second is a table name. The table name in the CREATE 
+** TRIGGER statement is replaced with the third argument and the result 
+** returned. This is analagous to renameTableFunc() above, except for CREATE
+** TRIGGER, not CREATE INDEX and CREATE TABLE.
+*/
+static void renameTriggerFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **argv
+){
+  unsigned char const *zSql = sqlite3_value_text(argv[0]);
+  unsigned char const *zTableName = sqlite3_value_text(argv[1]);
+
+  int token;
+  Token tname;
+  int dist = 3;
+  unsigned char const *zCsr = zSql;
+  int len = 0;
+  char *zRet;
+  sqlite3 *db = sqlite3_context_db_handle(context);
+
+  UNUSED_PARAMETER(NotUsed);
+
+  /* The principle used to locate the table name in the CREATE TRIGGER 
+  ** statement is that the table name is the first token that is immediately
+  ** preceded by either TK_ON or TK_DOT and immediately followed by one
+  ** of TK_WHEN, TK_BEGIN or TK_FOR.
+  */
+  if( zSql ){
+    do {
+
+      if( !*zCsr ){
+        /* Ran out of input before finding the table name. Return NULL. */
+        return;
+      }
+
+      /* Store the token that zCsr points to in tname. */
+      tname.z = (char*)zCsr;
+      tname.n = len;
+
+      /* Advance zCsr to the next token. Store that token type in 'token',
+      ** and its length in 'len' (to be used next iteration of this loop).
+      */
+      do {
+        zCsr += len;
+        len = sqlite3GetToken(zCsr, &token);
+      }while( token==TK_SPACE );
+      assert( len>0 );
+
+      /* Variable 'dist' stores the number of tokens read since the most
+      ** recent TK_DOT or TK_ON. This means that when a WHEN, FOR or BEGIN 
+      ** token is read and 'dist' equals 2, the condition stated above
+      ** to be met.
+      **
+      ** Note that ON cannot be a database, table or column name, so
+      ** there is no need to worry about syntax like 
+      ** "CREATE TRIGGER ... ON ON.ON BEGIN ..." etc.
+      */
+      dist++;
+      if( token==TK_DOT || token==TK_ON ){
+        dist = 0;
+      }
+    } while( dist!=2 || (token!=TK_WHEN && token!=TK_FOR && token!=TK_BEGIN) );
+
+    /* Variable tname now contains the token that is the old table-name
+    ** in the CREATE TRIGGER statement.
+    */
+    zRet = sqlite3MPrintf(db, "%.*s\"%w\"%s", (int)(((u8*)tname.z) - zSql),
+       zSql, zTableName, tname.z+tname.n);
+    sqlite3_result_text(context, zRet, -1, SQLITE_DYNAMIC);
+  }
+}
+#endif   /* !SQLITE_OMIT_TRIGGER */
+
+/*
+** Register built-in functions used to help implement ALTER TABLE
+*/
+SQLITE_PRIVATE void sqlite3AlterFunctions(void){
+  static FuncDef aAlterTableFuncs[] = {
+    FUNCTION(sqlite_rename_table,   2, 0, 0, renameTableFunc),
+#ifndef SQLITE_OMIT_TRIGGER
+    FUNCTION(sqlite_rename_trigger, 2, 0, 0, renameTriggerFunc),
+#endif
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+    FUNCTION(sqlite_rename_parent,  3, 0, 0, renameParentFunc),
+#endif
+  };
+  sqlite3InsertBuiltinFuncs(aAlterTableFuncs, ArraySize(aAlterTableFuncs));
+}
+
+/*
+** This function is used to create the text of expressions of the form:
+**
+**   name=<constant1> OR name=<constant2> OR ...
+**
+** If argument zWhere is NULL, then a pointer string containing the text 
+** "name=<constant>" is returned, where <constant> is the quoted version
+** of the string passed as argument zConstant. The returned buffer is
+** allocated using sqlite3DbMalloc(). It is the responsibility of the
+** caller to ensure that it is eventually freed.
+**
+** If argument zWhere is not NULL, then the string returned is 
+** "<where> OR name=<constant>", where <where> is the contents of zWhere.
+** In this case zWhere is passed to sqlite3DbFree() before returning.
+** 
+*/
+static char *whereOrName(sqlite3 *db, char *zWhere, char *zConstant){
+  char *zNew;
+  if( !zWhere ){
+    zNew = sqlite3MPrintf(db, "name=%Q", zConstant);
+  }else{
+    zNew = sqlite3MPrintf(db, "%s OR name=%Q", zWhere, zConstant);
+    sqlite3DbFree(db, zWhere);
+  }
+  return zNew;
+}
+
+#if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
+/*
+** Generate the text of a WHERE expression which can be used to select all
+** tables that have foreign key constraints that refer to table pTab (i.e.
+** constraints for which pTab is the parent table) from the sqlite_master
+** table.
+*/
+static char *whereForeignKeys(Parse *pParse, Table *pTab){
+  FKey *p;
+  char *zWhere = 0;
+  for(p=sqlite3FkReferences(pTab); p; p=p->pNextTo){
+    zWhere = whereOrName(pParse->db, zWhere, p->pFrom->zName);
+  }
+  return zWhere;
+}
+#endif
+
+/*
+** Generate the text of a WHERE expression which can be used to select all
+** temporary triggers on table pTab from the sqlite_temp_master table. If
+** table pTab has no temporary triggers, or is itself stored in the 
+** temporary database, NULL is returned.
+*/
+static char *whereTempTriggers(Parse *pParse, Table *pTab){
+  Trigger *pTrig;
+  char *zWhere = 0;
+  const Schema *pTempSchema = pParse->db->aDb[1].pSchema; /* Temp db schema */
+
+  /* If the table is not located in the temp-db (in which case NULL is 
+  ** returned, loop through the tables list of triggers. For each trigger
+  ** that is not part of the temp-db schema, add a clause to the WHERE 
+  ** expression being built up in zWhere.
+  */
+  if( pTab->pSchema!=pTempSchema ){
+    sqlite3 *db = pParse->db;
+    for(pTrig=sqlite3TriggerList(pParse, pTab); pTrig; pTrig=pTrig->pNext){
+      if( pTrig->pSchema==pTempSchema ){
+        zWhere = whereOrName(db, zWhere, pTrig->zName);
+      }
+    }
+  }
+  if( zWhere ){
+    char *zNew = sqlite3MPrintf(pParse->db, "type='trigger' AND (%s)", zWhere);
+    sqlite3DbFree(pParse->db, zWhere);
+    zWhere = zNew;
+  }
+  return zWhere;
+}
+
+/*
+** Generate code to drop and reload the internal representation of table
+** pTab from the database, including triggers and temporary triggers.
+** Argument zName is the name of the table in the database schema at
+** the time the generated code is executed. This can be different from
+** pTab->zName if this function is being called to code part of an 
+** "ALTER TABLE RENAME TO" statement.
+*/
+static void reloadTableSchema(Parse *pParse, Table *pTab, const char *zName){
+  Vdbe *v;
+  char *zWhere;
+  int iDb;                   /* Index of database containing pTab */
+#ifndef SQLITE_OMIT_TRIGGER
+  Trigger *pTrig;
+#endif
+
+  v = sqlite3GetVdbe(pParse);
+  if( NEVER(v==0) ) return;
+  assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
+  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
+  assert( iDb>=0 );
+
+#ifndef SQLITE_OMIT_TRIGGER
+  /* Drop any table triggers from the internal schema. */
+  for(pTrig=sqlite3TriggerList(pParse, pTab); pTrig; pTrig=pTrig->pNext){
+    int iTrigDb = sqlite3SchemaToIndex(pParse->db, pTrig->pSchema);
+    assert( iTrigDb==iDb || iTrigDb==1 );
+    sqlite3VdbeAddOp4(v, OP_DropTrigger, iTrigDb, 0, 0, pTrig->zName, 0);
+  }
+#endif
+
+  /* Drop the table and index from the internal schema.  */
+  sqlite3VdbeAddOp4(v, OP_DropTable, iDb, 0, 0, pTab->zName, 0);
+
+  /* Reload the table, index and permanent trigger schemas. */
+  zWhere = sqlite3MPrintf(pParse->db, "tbl_name=%Q", zName);
+  if( !zWhere ) return;
+  sqlite3VdbeAddParseSchemaOp(v, iDb, zWhere);
+
+#ifndef SQLITE_OMIT_TRIGGER
+  /* Now, if the table is not stored in the temp database, reload any temp 
+  ** triggers. Don't use IN(...) in case SQLITE_OMIT_SUBQUERY is defined. 
+  */
+  if( (zWhere=whereTempTriggers(pParse, pTab))!=0 ){
+    sqlite3VdbeAddParseSchemaOp(v, 1, zWhere);
+  }
+#endif
+}
+
+/*
+** Parameter zName is the name of a table that is about to be altered
+** (either with ALTER TABLE ... RENAME TO or ALTER TABLE ... ADD COLUMN).
+** If the table is a system table, this function leaves an error message
+** in pParse->zErr (system tables may not be altered) and returns non-zero.
+**
+** Or, if zName is not a system table, zero is returned.
+*/
+static int isSystemTable(Parse *pParse, const char *zName){
+  if( sqlite3Strlen30(zName)>6 && 0==sqlite3StrNICmp(zName, "sqlite_", 7) ){
+    sqlite3ErrorMsg(pParse, "table %s may not be altered", zName);
+    return 1;
+  }
+  return 0;
+}
+
+/*
+** Generate code to implement the "ALTER TABLE xxx RENAME TO yyy" 
+** command. 
+*/
+SQLITE_PRIVATE void sqlite3AlterRenameTable(
+  Parse *pParse,            /* Parser context. */
+  SrcList *pSrc,            /* The table to rename. */
+  Token *pName              /* The new table name. */
+){
+  int iDb;                  /* Database that contains the table */
+  char *zDb;                /* Name of database iDb */
+  Table *pTab;              /* Table being renamed */
+  char *zName = 0;          /* NULL-terminated version of pName */ 
+  sqlite3 *db = pParse->db; /* Database connection */
+  int nTabName;             /* Number of UTF-8 characters in zTabName */
+  const char *zTabName;     /* Original name of the table */
+  Vdbe *v;
+#ifndef SQLITE_OMIT_TRIGGER
+  char *zWhere = 0;         /* Where clause to locate temp triggers */
+#endif
+  VTable *pVTab = 0;        /* Non-zero if this is a v-tab with an xRename() */
+  int savedDbFlags;         /* Saved value of db->flags */
+
+  savedDbFlags = db->flags;  
+  if( NEVER(db->mallocFailed) ) goto exit_rename_table;
+  assert( pSrc->nSrc==1 );
+  assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
+
+  pTab = sqlite3LocateTableItem(pParse, 0, &pSrc->a[0]);
+  if( !pTab ) goto exit_rename_table;
+  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
+  zDb = db->aDb[iDb].zDbSName;
+  db->flags |= SQLITE_PreferBuiltin;
+
+  /* Get a NULL terminated version of the new table name. */
+  zName = sqlite3NameFromToken(db, pName);
+  if( !zName ) goto exit_rename_table;
+
+  /* Check that a table or index named 'zName' does not already exist
+  ** in database iDb. If so, this is an error.
+  */
+  if( sqlite3FindTable(db, zName, zDb) || sqlite3FindIndex(db, zName, zDb) ){
+    sqlite3ErrorMsg(pParse, 
+        "there is already another table or index with this name: %s", zName);
+    goto exit_rename_table;
+  }
+
+  /* Make sure it is not a system table being altered, or a reserved name
+  ** that the table is being renamed to.
+  */
+  if( SQLITE_OK!=isSystemTable(pParse, pTab->zName) ){
+    goto exit_rename_table;
+  }
+  if( SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){ goto
+    exit_rename_table;
+  }
+
+#ifndef SQLITE_OMIT_VIEW
+  if( pTab->pSelect ){
+    sqlite3ErrorMsg(pParse, "view %s may not be altered", pTab->zName);
+    goto exit_rename_table;
+  }
+#endif
+
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  /* Invoke the authorization callback. */
+  if( sqlite3AuthCheck(pParse, SQLITE_ALTER_TABLE, zDb, pTab->zName, 0) ){
+    goto exit_rename_table;
+  }
+#endif
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  if( sqlite3ViewGetColumnNames(pParse, pTab) ){
+    goto exit_rename_table;
+  }
+  if( IsVirtual(pTab) ){
+    pVTab = sqlite3GetVTable(db, pTab);
+    if( pVTab->pVtab->pModule->xRename==0 ){
+      pVTab = 0;
+    }
+  }
+#endif
+
+  /* Begin a transaction for database iDb. 
+  ** Then modify the schema cookie (since the ALTER TABLE modifies the
+  ** schema). Open a statement transaction if the table is a virtual
+  ** table.
+  */
+  v = sqlite3GetVdbe(pParse);
+  if( v==0 ){
+    goto exit_rename_table;
+  }
+  sqlite3BeginWriteOperation(pParse, pVTab!=0, iDb);
+  sqlite3ChangeCookie(pParse, iDb);
+
+  /* If this is a virtual table, invoke the xRename() function if
+  ** one is defined. The xRename() callback will modify the names
+  ** of any resources used by the v-table implementation (including other
+  ** SQLite tables) that are identified by the name of the virtual table.
+  */
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  if( pVTab ){
+    int i = ++pParse->nMem;
+    sqlite3VdbeLoadString(v, i, zName);
+    sqlite3VdbeAddOp4(v, OP_VRename, i, 0, 0,(const char*)pVTab, P4_VTAB);
+    sqlite3MayAbort(pParse);
+  }
+#endif
+
+  /* figure out how many UTF-8 characters are in zName */
+  zTabName = pTab->zName;
+  nTabName = sqlite3Utf8CharLen(zTabName, -1);
+
+#if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
+  if( db->flags&SQLITE_ForeignKeys ){
+    /* If foreign-key support is enabled, rewrite the CREATE TABLE 
+    ** statements corresponding to all child tables of foreign key constraints
+    ** for which the renamed table is the parent table.  */
+    if( (zWhere=whereForeignKeys(pParse, pTab))!=0 ){
+      sqlite3NestedParse(pParse, 
+          "UPDATE \"%w\".%s SET "
+              "sql = sqlite_rename_parent(sql, %Q, %Q) "
+              "WHERE %s;", zDb, SCHEMA_TABLE(iDb), zTabName, zName, zWhere);
+      sqlite3DbFree(db, zWhere);
+    }
+  }
+#endif
+
+  /* Modify the sqlite_master table to use the new table name. */
+  sqlite3NestedParse(pParse,
+      "UPDATE %Q.%s SET "
+#ifdef SQLITE_OMIT_TRIGGER
+          "sql = sqlite_rename_table(sql, %Q), "
+#else
+          "sql = CASE "
+            "WHEN type = 'trigger' THEN sqlite_rename_trigger(sql, %Q)"
+            "ELSE sqlite_rename_table(sql, %Q) END, "
+#endif
+          "tbl_name = %Q, "
+          "name = CASE "
+            "WHEN type='table' THEN %Q "
+            "WHEN name LIKE 'sqlite_autoindex%%' AND type='index' THEN "
+             "'sqlite_autoindex_' || %Q || substr(name,%d+18) "
+            "ELSE name END "
+      "WHERE tbl_name=%Q COLLATE nocase AND "
+          "(type='table' OR type='index' OR type='trigger');", 
+      zDb, SCHEMA_TABLE(iDb), zName, zName, zName, 
+#ifndef SQLITE_OMIT_TRIGGER
+      zName,
+#endif
+      zName, nTabName, zTabName
+  );
+
+#ifndef SQLITE_OMIT_AUTOINCREMENT
+  /* If the sqlite_sequence table exists in this database, then update 
+  ** it with the new table name.
+  */
+  if( sqlite3FindTable(db, "sqlite_sequence", zDb) ){
+    sqlite3NestedParse(pParse,
+        "UPDATE \"%w\".sqlite_sequence set name = %Q WHERE name = %Q",
+        zDb, zName, pTab->zName);
+  }
+#endif
+
+#ifndef SQLITE_OMIT_TRIGGER
+  /* If there are TEMP triggers on this table, modify the sqlite_temp_master
+  ** table. Don't do this if the table being ALTERed is itself located in
+  ** the temp database.
+  */
+  if( (zWhere=whereTempTriggers(pParse, pTab))!=0 ){
+    sqlite3NestedParse(pParse, 
+        "UPDATE sqlite_temp_master SET "
+            "sql = sqlite_rename_trigger(sql, %Q), "
+            "tbl_name = %Q "
+            "WHERE %s;", zName, zName, zWhere);
+    sqlite3DbFree(db, zWhere);
+  }
+#endif
+
+#if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
+  if( db->flags&SQLITE_ForeignKeys ){
+    FKey *p;
+    for(p=sqlite3FkReferences(pTab); p; p=p->pNextTo){
+      Table *pFrom = p->pFrom;
+      if( pFrom!=pTab ){
+        reloadTableSchema(pParse, p->pFrom, pFrom->zName);
+      }
+    }
+  }
+#endif
+
+  /* Drop and reload the internal table schema. */
+  reloadTableSchema(pParse, pTab, zName);
+
+exit_rename_table:
+  sqlite3SrcListDelete(db, pSrc);
+  sqlite3DbFree(db, zName);
+  db->flags = savedDbFlags;
+}
+
+/*
+** This function is called after an "ALTER TABLE ... ADD" statement
+** has been parsed. Argument pColDef contains the text of the new
+** column definition.
+**
+** The Table structure pParse->pNewTable was extended to include
+** the new column during parsing.
+*/
+SQLITE_PRIVATE void sqlite3AlterFinishAddColumn(Parse *pParse, Token *pColDef){
+  Table *pNew;              /* Copy of pParse->pNewTable */
+  Table *pTab;              /* Table being altered */
+  int iDb;                  /* Database number */
+  const char *zDb;          /* Database name */
+  const char *zTab;         /* Table name */
+  char *zCol;               /* Null-terminated column definition */
+  Column *pCol;             /* The new column */
+  Expr *pDflt;              /* Default value for the new column */
+  sqlite3 *db;              /* The database connection; */
+  Vdbe *v = pParse->pVdbe;  /* The prepared statement under construction */
+  int r1;                   /* Temporary registers */
+
+  db = pParse->db;
+  if( pParse->nErr || db->mallocFailed ) return;
+  assert( v!=0 );
+  pNew = pParse->pNewTable;
+  assert( pNew );
+
+  assert( sqlite3BtreeHoldsAllMutexes(db) );
+  iDb = sqlite3SchemaToIndex(db, pNew->pSchema);
+  zDb = db->aDb[iDb].zDbSName;
+  zTab = &pNew->zName[16];  /* Skip the "sqlite_altertab_" prefix on the name */
+  pCol = &pNew->aCol[pNew->nCol-1];
+  pDflt = pCol->pDflt;
+  pTab = sqlite3FindTable(db, zTab, zDb);
+  assert( pTab );
+
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  /* Invoke the authorization callback. */
+  if( sqlite3AuthCheck(pParse, SQLITE_ALTER_TABLE, zDb, pTab->zName, 0) ){
+    return;
+  }
+#endif
+
+  /* If the default value for the new column was specified with a 
+  ** literal NULL, then set pDflt to 0. This simplifies checking
+  ** for an SQL NULL default below.
+  */
+  assert( pDflt==0 || pDflt->op==TK_SPAN );
+  if( pDflt && pDflt->pLeft->op==TK_NULL ){
+    pDflt = 0;
+  }
+
+  /* Check that the new column is not specified as PRIMARY KEY or UNIQUE.
+  ** If there is a NOT NULL constraint, then the default value for the
+  ** column must not be NULL.
+  */
+  if( pCol->colFlags & COLFLAG_PRIMKEY ){
+    sqlite3ErrorMsg(pParse, "Cannot add a PRIMARY KEY column");
+    return;
+  }
+  if( pNew->pIndex ){
+    sqlite3ErrorMsg(pParse, "Cannot add a UNIQUE column");
+    return;
+  }
+  if( (db->flags&SQLITE_ForeignKeys) && pNew->pFKey && pDflt ){
+    sqlite3ErrorMsg(pParse, 
+        "Cannot add a REFERENCES column with non-NULL default value");
+    return;
+  }
+  if( pCol->notNull && !pDflt ){
+    sqlite3ErrorMsg(pParse, 
+        "Cannot add a NOT NULL column with default value NULL");
+    return;
+  }
+
+  /* Ensure the default expression is something that sqlite3ValueFromExpr()
+  ** can handle (i.e. not CURRENT_TIME etc.)
+  */
+  if( pDflt ){
+    sqlite3_value *pVal = 0;
+    int rc;
+    rc = sqlite3ValueFromExpr(db, pDflt, SQLITE_UTF8, SQLITE_AFF_BLOB, &pVal);
+    assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
+    if( rc!=SQLITE_OK ){
+      assert( db->mallocFailed == 1 );
+      return;
+    }
+    if( !pVal ){
+      sqlite3ErrorMsg(pParse, "Cannot add a column with non-constant default");
+      return;
+    }
+    sqlite3ValueFree(pVal);
+  }
+
+  /* Modify the CREATE TABLE statement. */
+  zCol = sqlite3DbStrNDup(db, (char*)pColDef->z, pColDef->n);
+  if( zCol ){
+    char *zEnd = &zCol[pColDef->n-1];
+    int savedDbFlags = db->flags;
+    while( zEnd>zCol && (*zEnd==';' || sqlite3Isspace(*zEnd)) ){
+      *zEnd-- = '\0';
+    }
+    db->flags |= SQLITE_PreferBuiltin;
+    sqlite3NestedParse(pParse, 
+        "UPDATE \"%w\".%s SET "
+          "sql = substr(sql,1,%d) || ', ' || %Q || substr(sql,%d) "
+        "WHERE type = 'table' AND name = %Q", 
+      zDb, SCHEMA_TABLE(iDb), pNew->addColOffset, zCol, pNew->addColOffset+1,
+      zTab
+    );
+    sqlite3DbFree(db, zCol);
+    db->flags = savedDbFlags;
+  }
+
+  /* Make sure the schema version is at least 3.  But do not upgrade
+  ** from less than 3 to 4, as that will corrupt any preexisting DESC
+  ** index.
+  */
+  r1 = sqlite3GetTempReg(pParse);
+  sqlite3VdbeAddOp3(v, OP_ReadCookie, iDb, r1, BTREE_FILE_FORMAT);
+  sqlite3VdbeUsesBtree(v, iDb);
+  sqlite3VdbeAddOp2(v, OP_AddImm, r1, -2);
+  sqlite3VdbeAddOp2(v, OP_IfPos, r1, sqlite3VdbeCurrentAddr(v)+2);
+  VdbeCoverage(v);
+  sqlite3VdbeAddOp3(v, OP_SetCookie, iDb, BTREE_FILE_FORMAT, 3);
+  sqlite3ReleaseTempReg(pParse, r1);
+
+  /* Reload the schema of the modified table. */
+  reloadTableSchema(pParse, pTab, pTab->zName);
+}
+
+/*
+** This function is called by the parser after the table-name in
+** an "ALTER TABLE <table-name> ADD" statement is parsed. Argument 
+** pSrc is the full-name of the table being altered.
+**
+** This routine makes a (partial) copy of the Table structure
+** for the table being altered and sets Parse.pNewTable to point
+** to it. Routines called by the parser as the column definition
+** is parsed (i.e. sqlite3AddColumn()) add the new Column data to 
+** the copy. The copy of the Table structure is deleted by tokenize.c 
+** after parsing is finished.
+**
+** Routine sqlite3AlterFinishAddColumn() will be called to complete
+** coding the "ALTER TABLE ... ADD" statement.
+*/
+SQLITE_PRIVATE void sqlite3AlterBeginAddColumn(Parse *pParse, SrcList *pSrc){
+  Table *pNew;
+  Table *pTab;
+  Vdbe *v;
+  int iDb;
+  int i;
+  int nAlloc;
+  sqlite3 *db = pParse->db;
+
+  /* Look up the table being altered. */
+  assert( pParse->pNewTable==0 );
+  assert( sqlite3BtreeHoldsAllMutexes(db) );
+  if( db->mallocFailed ) goto exit_begin_add_column;
+  pTab = sqlite3LocateTableItem(pParse, 0, &pSrc->a[0]);
+  if( !pTab ) goto exit_begin_add_column;
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  if( IsVirtual(pTab) ){
+    sqlite3ErrorMsg(pParse, "virtual tables may not be altered");
+    goto exit_begin_add_column;
+  }
+#endif
+
+  /* Make sure this is not an attempt to ALTER a view. */
+  if( pTab->pSelect ){
+    sqlite3ErrorMsg(pParse, "Cannot add a column to a view");
+    goto exit_begin_add_column;
+  }
+  if( SQLITE_OK!=isSystemTable(pParse, pTab->zName) ){
+    goto exit_begin_add_column;
+  }
+
+  assert( pTab->addColOffset>0 );
+  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+
+  /* Put a copy of the Table struct in Parse.pNewTable for the
+  ** sqlite3AddColumn() function and friends to modify.  But modify
+  ** the name by adding an "sqlite_altertab_" prefix.  By adding this
+  ** prefix, we insure that the name will not collide with an existing
+  ** table because user table are not allowed to have the "sqlite_"
+  ** prefix on their name.
+  */
+  pNew = (Table*)sqlite3DbMallocZero(db, sizeof(Table));
+  if( !pNew ) goto exit_begin_add_column;
+  pParse->pNewTable = pNew;
+  pNew->nRef = 1;
+  pNew->nCol = pTab->nCol;
+  assert( pNew->nCol>0 );
+  nAlloc = (((pNew->nCol-1)/8)*8)+8;
+  assert( nAlloc>=pNew->nCol && nAlloc%8==0 && nAlloc-pNew->nCol<8 );
+  pNew->aCol = (Column*)sqlite3DbMallocZero(db, sizeof(Column)*nAlloc);
+  pNew->zName = sqlite3MPrintf(db, "sqlite_altertab_%s", pTab->zName);
+  if( !pNew->aCol || !pNew->zName ){
+    assert( db->mallocFailed );
+    goto exit_begin_add_column;
+  }
+  memcpy(pNew->aCol, pTab->aCol, sizeof(Column)*pNew->nCol);
+  for(i=0; i<pNew->nCol; i++){
+    Column *pCol = &pNew->aCol[i];
+    pCol->zName = sqlite3DbStrDup(db, pCol->zName);
+    pCol->zColl = 0;
+    pCol->pDflt = 0;
+  }
+  pNew->pSchema = db->aDb[iDb].pSchema;
+  pNew->addColOffset = pTab->addColOffset;
+  pNew->nRef = 1;
+
+  /* Begin a transaction and increment the schema cookie.  */
+  sqlite3BeginWriteOperation(pParse, 0, iDb);
+  v = sqlite3GetVdbe(pParse);
+  if( !v ) goto exit_begin_add_column;
+  sqlite3ChangeCookie(pParse, iDb);
+
+exit_begin_add_column:
+  sqlite3SrcListDelete(db, pSrc);
+  return;
+}
+#endif  /* SQLITE_ALTER_TABLE */
+
+/************** End of alter.c ***********************************************/
+/************** Begin file analyze.c *****************************************/
+/*
+** 2005-07-08
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains code associated with the ANALYZE command.
+**
+** The ANALYZE command gather statistics about the content of tables
+** and indices.  These statistics are made available to the query planner
+** to help it make better decisions about how to perform queries.
+**
+** The following system tables are or have been supported:
+**
+**    CREATE TABLE sqlite_stat1(tbl, idx, stat);
+**    CREATE TABLE sqlite_stat2(tbl, idx, sampleno, sample);
+**    CREATE TABLE sqlite_stat3(tbl, idx, nEq, nLt, nDLt, sample);
+**    CREATE TABLE sqlite_stat4(tbl, idx, nEq, nLt, nDLt, sample);
+**
+** Additional tables might be added in future releases of SQLite.
+** The sqlite_stat2 table is not created or used unless the SQLite version
+** is between 3.6.18 and 3.7.8, inclusive, and unless SQLite is compiled
+** with SQLITE_ENABLE_STAT2.  The sqlite_stat2 table is deprecated.
+** The sqlite_stat2 table is superseded by sqlite_stat3, which is only
+** created and used by SQLite versions 3.7.9 and later and with
+** SQLITE_ENABLE_STAT3 defined.  The functionality of sqlite_stat3
+** is a superset of sqlite_stat2.  The sqlite_stat4 is an enhanced
+** version of sqlite_stat3 and is only available when compiled with
+** SQLITE_ENABLE_STAT4 and in SQLite versions 3.8.1 and later.  It is
+** not possible to enable both STAT3 and STAT4 at the same time.  If they
+** are both enabled, then STAT4 takes precedence.
+**
+** For most applications, sqlite_stat1 provides all the statistics required
+** for the query planner to make good choices.
+**
+** Format of sqlite_stat1:
+**
+** There is normally one row per index, with the index identified by the
+** name in the idx column.  The tbl column is the name of the table to
+** which the index belongs.  In each such row, the stat column will be
+** a string consisting of a list of integers.  The first integer in this
+** list is the number of rows in the index.  (This is the same as the
+** number of rows in the table, except for partial indices.)  The second
+** integer is the average number of rows in the index that have the same
+** value in the first column of the index.  The third integer is the average
+** number of rows in the index that have the same value for the first two
+** columns.  The N-th integer (for N>1) is the average number of rows in 
+** the index which have the same value for the first N-1 columns.  For
+** a K-column index, there will be K+1 integers in the stat column.  If
+** the index is unique, then the last integer will be 1.
+**
+** The list of integers in the stat column can optionally be followed
+** by the keyword "unordered".  The "unordered" keyword, if it is present,
+** must be separated from the last integer by a single space.  If the
+** "unordered" keyword is present, then the query planner assumes that
+** the index is unordered and will not use the index for a range query.
+** 
+** If the sqlite_stat1.idx column is NULL, then the sqlite_stat1.stat
+** column contains a single integer which is the (estimated) number of
+** rows in the table identified by sqlite_stat1.tbl.
+**
+** Format of sqlite_stat2:
+**
+** The sqlite_stat2 is only created and is only used if SQLite is compiled
+** with SQLITE_ENABLE_STAT2 and if the SQLite version number is between
+** 3.6.18 and 3.7.8.  The "stat2" table contains additional information
+** about the distribution of keys within an index.  The index is identified by
+** the "idx" column and the "tbl" column is the name of the table to which
+** the index belongs.  There are usually 10 rows in the sqlite_stat2
+** table for each index.
+**
+** The sqlite_stat2 entries for an index that have sampleno between 0 and 9
+** inclusive are samples of the left-most key value in the index taken at
+** evenly spaced points along the index.  Let the number of samples be S
+** (10 in the standard build) and let C be the number of rows in the index.
+** Then the sampled rows are given by:
+**
+**     rownumber = (i*C*2 + C)/(S*2)
+**
+** For i between 0 and S-1.  Conceptually, the index space is divided into
+** S uniform buckets and the samples are the middle row from each bucket.
+**
+** The format for sqlite_stat2 is recorded here for legacy reference.  This
+** version of SQLite does not support sqlite_stat2.  It neither reads nor
+** writes the sqlite_stat2 table.  This version of SQLite only supports
+** sqlite_stat3.
+**
+** Format for sqlite_stat3:
+**
+** The sqlite_stat3 format is a subset of sqlite_stat4.  Hence, the
+** sqlite_stat4 format will be described first.  Further information
+** about sqlite_stat3 follows the sqlite_stat4 description.
+**
+** Format for sqlite_stat4:
+**
+** As with sqlite_stat2, the sqlite_stat4 table contains histogram data
+** to aid the query planner in choosing good indices based on the values
+** that indexed columns are compared against in the WHERE clauses of
+** queries.
+**
+** The sqlite_stat4 table contains multiple entries for each index.
+** The idx column names the index and the tbl column is the table of the
+** index.  If the idx and tbl columns are the same, then the sample is
+** of the INTEGER PRIMARY KEY.  The sample column is a blob which is the
+** binary encoding of a key from the index.  The nEq column is a
+** list of integers.  The first integer is the approximate number
+** of entries in the index whose left-most column exactly matches
+** the left-most column of the sample.  The second integer in nEq
+** is the approximate number of entries in the index where the
+** first two columns match the first two columns of the sample.
+** And so forth.  nLt is another list of integers that show the approximate
+** number of entries that are strictly less than the sample.  The first
+** integer in nLt contains the number of entries in the index where the
+** left-most column is less than the left-most column of the sample.
+** The K-th integer in the nLt entry is the number of index entries 
+** where the first K columns are less than the first K columns of the
+** sample.  The nDLt column is like nLt except that it contains the 
+** number of distinct entries in the index that are less than the
+** sample.
+**
+** There can be an arbitrary number of sqlite_stat4 entries per index.
+** The ANALYZE command will typically generate sqlite_stat4 tables
+** that contain between 10 and 40 samples which are distributed across
+** the key space, though not uniformly, and which include samples with
+** large nEq values.
+**
+** Format for sqlite_stat3 redux:
+**
+** The sqlite_stat3 table is like sqlite_stat4 except that it only
+** looks at the left-most column of the index.  The sqlite_stat3.sample
+** column contains the actual value of the left-most column instead
+** of a blob encoding of the complete index key as is found in
+** sqlite_stat4.sample.  The nEq, nLt, and nDLt entries of sqlite_stat3
+** all contain just a single integer which is the same as the first
+** integer in the equivalent columns in sqlite_stat4.
+*/
+#ifndef SQLITE_OMIT_ANALYZE
+/* #include "sqliteInt.h" */
+
+#if defined(SQLITE_ENABLE_STAT4)
+# define IsStat4     1
+# define IsStat3     0
+#elif defined(SQLITE_ENABLE_STAT3)
+# define IsStat4     0
+# define IsStat3     1
+#else
+# define IsStat4     0
+# define IsStat3     0
+# undef SQLITE_STAT4_SAMPLES
+# define SQLITE_STAT4_SAMPLES 1
+#endif
+#define IsStat34    (IsStat3+IsStat4)  /* 1 for STAT3 or STAT4. 0 otherwise */
+
+/*
+** This routine generates code that opens the sqlite_statN tables.
+** The sqlite_stat1 table is always relevant.  sqlite_stat2 is now
+** obsolete.  sqlite_stat3 and sqlite_stat4 are only opened when
+** appropriate compile-time options are provided.
+**
+** If the sqlite_statN tables do not previously exist, it is created.
+**
+** Argument zWhere may be a pointer to a buffer containing a table name,
+** or it may be a NULL pointer. If it is not NULL, then all entries in
+** the sqlite_statN tables associated with the named table are deleted.
+** If zWhere==0, then code is generated to delete all stat table entries.
+*/
+static void openStatTable(
+  Parse *pParse,          /* Parsing context */
+  int iDb,                /* The database we are looking in */
+  int iStatCur,           /* Open the sqlite_stat1 table on this cursor */
+  const char *zWhere,     /* Delete entries for this table or index */
+  const char *zWhereType  /* Either "tbl" or "idx" */
+){
+  static const struct {
+    const char *zName;
+    const char *zCols;
+  } aTable[] = {
+    { "sqlite_stat1", "tbl,idx,stat" },
+#if defined(SQLITE_ENABLE_STAT4)
+    { "sqlite_stat4", "tbl,idx,neq,nlt,ndlt,sample" },
+    { "sqlite_stat3", 0 },
+#elif defined(SQLITE_ENABLE_STAT3)
+    { "sqlite_stat3", "tbl,idx,neq,nlt,ndlt,sample" },
+    { "sqlite_stat4", 0 },
+#else
+    { "sqlite_stat3", 0 },
+    { "sqlite_stat4", 0 },
+#endif
+  };
+  int i;
+  sqlite3 *db = pParse->db;
+  Db *pDb;
+  Vdbe *v = sqlite3GetVdbe(pParse);
+  int aRoot[ArraySize(aTable)];
+  u8 aCreateTbl[ArraySize(aTable)];
+
+  if( v==0 ) return;
+  assert( sqlite3BtreeHoldsAllMutexes(db) );
+  assert( sqlite3VdbeDb(v)==db );
+  pDb = &db->aDb[iDb];
+
+  /* Create new statistic tables if they do not exist, or clear them
+  ** if they do already exist.
+  */
+  for(i=0; i<ArraySize(aTable); i++){
+    const char *zTab = aTable[i].zName;
+    Table *pStat;
+    if( (pStat = sqlite3FindTable(db, zTab, pDb->zDbSName))==0 ){
+      if( aTable[i].zCols ){
+        /* The sqlite_statN table does not exist. Create it. Note that a 
+        ** side-effect of the CREATE TABLE statement is to leave the rootpage 
+        ** of the new table in register pParse->regRoot. This is important 
+        ** because the OpenWrite opcode below will be needing it. */
+        sqlite3NestedParse(pParse,
+            "CREATE TABLE %Q.%s(%s)", pDb->zDbSName, zTab, aTable[i].zCols
+        );
+        aRoot[i] = pParse->regRoot;
+        aCreateTbl[i] = OPFLAG_P2ISREG;
+      }
+    }else{
+      /* The table already exists. If zWhere is not NULL, delete all entries 
+      ** associated with the table zWhere. If zWhere is NULL, delete the
+      ** entire contents of the table. */
+      aRoot[i] = pStat->tnum;
+      aCreateTbl[i] = 0;
+      sqlite3TableLock(pParse, iDb, aRoot[i], 1, zTab);
+      if( zWhere ){
+        sqlite3NestedParse(pParse,
+           "DELETE FROM %Q.%s WHERE %s=%Q",
+           pDb->zDbSName, zTab, zWhereType, zWhere
+        );
+      }else{
+        /* The sqlite_stat[134] table already exists.  Delete all rows. */
+        sqlite3VdbeAddOp2(v, OP_Clear, aRoot[i], iDb);
+      }
+    }
+  }
+
+  /* Open the sqlite_stat[134] tables for writing. */
+  for(i=0; aTable[i].zCols; i++){
+    assert( i<ArraySize(aTable) );
+    sqlite3VdbeAddOp4Int(v, OP_OpenWrite, iStatCur+i, aRoot[i], iDb, 3);
+    sqlite3VdbeChangeP5(v, aCreateTbl[i]);
+    VdbeComment((v, aTable[i].zName));
+  }
+}
+
+/*
+** Recommended number of samples for sqlite_stat4
+*/
+#ifndef SQLITE_STAT4_SAMPLES
+# define SQLITE_STAT4_SAMPLES 24
+#endif
+
+/*
+** Three SQL functions - stat_init(), stat_push(), and stat_get() -
+** share an instance of the following structure to hold their state
+** information.
+*/
+typedef struct Stat4Accum Stat4Accum;
+typedef struct Stat4Sample Stat4Sample;
+struct Stat4Sample {
+  tRowcnt *anEq;                  /* sqlite_stat4.nEq */
+  tRowcnt *anDLt;                 /* sqlite_stat4.nDLt */
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  tRowcnt *anLt;                  /* sqlite_stat4.nLt */
+  union {
+    i64 iRowid;                     /* Rowid in main table of the key */
+    u8 *aRowid;                     /* Key for WITHOUT ROWID tables */
+  } u;
+  u32 nRowid;                     /* Sizeof aRowid[] */
+  u8 isPSample;                   /* True if a periodic sample */
+  int iCol;                       /* If !isPSample, the reason for inclusion */
+  u32 iHash;                      /* Tiebreaker hash */
+#endif
+};                                                    
+struct Stat4Accum {
+  tRowcnt nRow;             /* Number of rows in the entire table */
+  tRowcnt nPSample;         /* How often to do a periodic sample */
+  int nCol;                 /* Number of columns in index + pk/rowid */
+  int nKeyCol;              /* Number of index columns w/o the pk/rowid */
+  int mxSample;             /* Maximum number of samples to accumulate */
+  Stat4Sample current;      /* Current row as a Stat4Sample */
+  u32 iPrn;                 /* Pseudo-random number used for sampling */
+  Stat4Sample *aBest;       /* Array of nCol best samples */
+  int iMin;                 /* Index in a[] of entry with minimum score */
+  int nSample;              /* Current number of samples */
+  int iGet;                 /* Index of current sample accessed by stat_get() */
+  Stat4Sample *a;           /* Array of mxSample Stat4Sample objects */
+  sqlite3 *db;              /* Database connection, for malloc() */
+};
+
+/* Reclaim memory used by a Stat4Sample
+*/
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+static void sampleClear(sqlite3 *db, Stat4Sample *p){
+  assert( db!=0 );
+  if( p->nRowid ){
+    sqlite3DbFree(db, p->u.aRowid);
+    p->nRowid = 0;
+  }
+}
+#endif
+
+/* Initialize the BLOB value of a ROWID
+*/
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+static void sampleSetRowid(sqlite3 *db, Stat4Sample *p, int n, const u8 *pData){
+  assert( db!=0 );
+  if( p->nRowid ) sqlite3DbFree(db, p->u.aRowid);
+  p->u.aRowid = sqlite3DbMallocRawNN(db, n);
+  if( p->u.aRowid ){
+    p->nRowid = n;
+    memcpy(p->u.aRowid, pData, n);
+  }else{
+    p->nRowid = 0;
+  }
+}
+#endif
+
+/* Initialize the INTEGER value of a ROWID.
+*/
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+static void sampleSetRowidInt64(sqlite3 *db, Stat4Sample *p, i64 iRowid){
+  assert( db!=0 );
+  if( p->nRowid ) sqlite3DbFree(db, p->u.aRowid);
+  p->nRowid = 0;
+  p->u.iRowid = iRowid;
+}
+#endif
+
+
+/*
+** Copy the contents of object (*pFrom) into (*pTo).
+*/
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+static void sampleCopy(Stat4Accum *p, Stat4Sample *pTo, Stat4Sample *pFrom){
+  pTo->isPSample = pFrom->isPSample;
+  pTo->iCol = pFrom->iCol;
+  pTo->iHash = pFrom->iHash;
+  memcpy(pTo->anEq, pFrom->anEq, sizeof(tRowcnt)*p->nCol);
+  memcpy(pTo->anLt, pFrom->anLt, sizeof(tRowcnt)*p->nCol);
+  memcpy(pTo->anDLt, pFrom->anDLt, sizeof(tRowcnt)*p->nCol);
+  if( pFrom->nRowid ){
+    sampleSetRowid(p->db, pTo, pFrom->nRowid, pFrom->u.aRowid);
+  }else{
+    sampleSetRowidInt64(p->db, pTo, pFrom->u.iRowid);
+  }
+}
+#endif
+
+/*
+** Reclaim all memory of a Stat4Accum structure.
+*/
+static void stat4Destructor(void *pOld){
+  Stat4Accum *p = (Stat4Accum*)pOld;
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  int i;
+  for(i=0; i<p->nCol; i++) sampleClear(p->db, p->aBest+i);
+  for(i=0; i<p->mxSample; i++) sampleClear(p->db, p->a+i);
+  sampleClear(p->db, &p->current);
+#endif
+  sqlite3DbFree(p->db, p);
+}
+
+/*
+** Implementation of the stat_init(N,K,C) SQL function. The three parameters
+** are:
+**     N:    The number of columns in the index including the rowid/pk (note 1)
+**     K:    The number of columns in the index excluding the rowid/pk.
+**     C:    The number of rows in the index (note 2)
+**
+** Note 1:  In the special case of the covering index that implements a
+** WITHOUT ROWID table, N is the number of PRIMARY KEY columns, not the
+** total number of columns in the table.
+**
+** Note 2:  C is only used for STAT3 and STAT4.
+**
+** For indexes on ordinary rowid tables, N==K+1.  But for indexes on
+** WITHOUT ROWID tables, N=K+P where P is the number of columns in the
+** PRIMARY KEY of the table.  The covering index that implements the
+** original WITHOUT ROWID table as N==K as a special case.
+**
+** This routine allocates the Stat4Accum object in heap memory. The return 
+** value is a pointer to the Stat4Accum object.  The datatype of the
+** return value is BLOB, but it is really just a pointer to the Stat4Accum
+** object.
+*/
+static void statInit(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  Stat4Accum *p;
+  int nCol;                       /* Number of columns in index being sampled */
+  int nKeyCol;                    /* Number of key columns */
+  int nColUp;                     /* nCol rounded up for alignment */
+  int n;                          /* Bytes of space to allocate */
+  sqlite3 *db;                    /* Database connection */
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  int mxSample = SQLITE_STAT4_SAMPLES;
+#endif
+
+  /* Decode the three function arguments */
+  UNUSED_PARAMETER(argc);
+  nCol = sqlite3_value_int(argv[0]);
+  assert( nCol>0 );
+  nColUp = sizeof(tRowcnt)<8 ? (nCol+1)&~1 : nCol;
+  nKeyCol = sqlite3_value_int(argv[1]);
+  assert( nKeyCol<=nCol );
+  assert( nKeyCol>0 );
+
+  /* Allocate the space required for the Stat4Accum object */
+  n = sizeof(*p) 
+    + sizeof(tRowcnt)*nColUp                  /* Stat4Accum.anEq */
+    + sizeof(tRowcnt)*nColUp                  /* Stat4Accum.anDLt */
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+    + sizeof(tRowcnt)*nColUp                  /* Stat4Accum.anLt */
+    + sizeof(Stat4Sample)*(nCol+mxSample)     /* Stat4Accum.aBest[], a[] */
+    + sizeof(tRowcnt)*3*nColUp*(nCol+mxSample)
+#endif
+  ;
+  db = sqlite3_context_db_handle(context);
+  p = sqlite3DbMallocZero(db, n);
+  if( p==0 ){
+    sqlite3_result_error_nomem(context);
+    return;
+  }
+
+  p->db = db;
+  p->nRow = 0;
+  p->nCol = nCol;
+  p->nKeyCol = nKeyCol;
+  p->current.anDLt = (tRowcnt*)&p[1];
+  p->current.anEq = &p->current.anDLt[nColUp];
+
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  {
+    u8 *pSpace;                     /* Allocated space not yet assigned */
+    int i;                          /* Used to iterate through p->aSample[] */
+
+    p->iGet = -1;
+    p->mxSample = mxSample;
+    p->nPSample = (tRowcnt)(sqlite3_value_int64(argv[2])/(mxSample/3+1) + 1);
+    p->current.anLt = &p->current.anEq[nColUp];
+    p->iPrn = 0x689e962d*(u32)nCol ^ 0xd0944565*(u32)sqlite3_value_int(argv[2]);
+  
+    /* Set up the Stat4Accum.a[] and aBest[] arrays */
+    p->a = (struct Stat4Sample*)&p->current.anLt[nColUp];
+    p->aBest = &p->a[mxSample];
+    pSpace = (u8*)(&p->a[mxSample+nCol]);
+    for(i=0; i<(mxSample+nCol); i++){
+      p->a[i].anEq = (tRowcnt *)pSpace; pSpace += (sizeof(tRowcnt) * nColUp);
+      p->a[i].anLt = (tRowcnt *)pSpace; pSpace += (sizeof(tRowcnt) * nColUp);
+      p->a[i].anDLt = (tRowcnt *)pSpace; pSpace += (sizeof(tRowcnt) * nColUp);
+    }
+    assert( (pSpace - (u8*)p)==n );
+  
+    for(i=0; i<nCol; i++){
+      p->aBest[i].iCol = i;
+    }
+  }
+#endif
+
+  /* Return a pointer to the allocated object to the caller.  Note that
+  ** only the pointer (the 2nd parameter) matters.  The size of the object
+  ** (given by the 3rd parameter) is never used and can be any positive
+  ** value. */
+  sqlite3_result_blob(context, p, sizeof(*p), stat4Destructor);
+}
+static const FuncDef statInitFuncdef = {
+  2+IsStat34,      /* nArg */
+  SQLITE_UTF8,     /* funcFlags */
+  0,               /* pUserData */
+  0,               /* pNext */
+  statInit,        /* xSFunc */
+  0,               /* xFinalize */
+  "stat_init",     /* zName */
+  {0}
+};
+
+#ifdef SQLITE_ENABLE_STAT4
+/*
+** pNew and pOld are both candidate non-periodic samples selected for 
+** the same column (pNew->iCol==pOld->iCol). Ignoring this column and 
+** considering only any trailing columns and the sample hash value, this
+** function returns true if sample pNew is to be preferred over pOld.
+** In other words, if we assume that the cardinalities of the selected
+** column for pNew and pOld are equal, is pNew to be preferred over pOld.
+**
+** This function assumes that for each argument sample, the contents of
+** the anEq[] array from pSample->anEq[pSample->iCol+1] onwards are valid. 
+*/
+static int sampleIsBetterPost(
+  Stat4Accum *pAccum, 
+  Stat4Sample *pNew, 
+  Stat4Sample *pOld
+){
+  int nCol = pAccum->nCol;
+  int i;
+  assert( pNew->iCol==pOld->iCol );
+  for(i=pNew->iCol+1; i<nCol; i++){
+    if( pNew->anEq[i]>pOld->anEq[i] ) return 1;
+    if( pNew->anEq[i]<pOld->anEq[i] ) return 0;
+  }
+  if( pNew->iHash>pOld->iHash ) return 1;
+  return 0;
+}
+#endif
+
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+/*
+** Return true if pNew is to be preferred over pOld.
+**
+** This function assumes that for each argument sample, the contents of
+** the anEq[] array from pSample->anEq[pSample->iCol] onwards are valid. 
+*/
+static int sampleIsBetter(
+  Stat4Accum *pAccum, 
+  Stat4Sample *pNew, 
+  Stat4Sample *pOld
+){
+  tRowcnt nEqNew = pNew->anEq[pNew->iCol];
+  tRowcnt nEqOld = pOld->anEq[pOld->iCol];
+
+  assert( pOld->isPSample==0 && pNew->isPSample==0 );
+  assert( IsStat4 || (pNew->iCol==0 && pOld->iCol==0) );
+
+  if( (nEqNew>nEqOld) ) return 1;
+#ifdef SQLITE_ENABLE_STAT4
+  if( nEqNew==nEqOld ){
+    if( pNew->iCol<pOld->iCol ) return 1;
+    return (pNew->iCol==pOld->iCol && sampleIsBetterPost(pAccum, pNew, pOld));
+  }
+  return 0;
+#else
+  return (nEqNew==nEqOld && pNew->iHash>pOld->iHash);
+#endif
+}
+
+/*
+** Copy the contents of sample *pNew into the p->a[] array. If necessary,
+** remove the least desirable sample from p->a[] to make room.
+*/
+static void sampleInsert(Stat4Accum *p, Stat4Sample *pNew, int nEqZero){
+  Stat4Sample *pSample = 0;
+  int i;
+
+  assert( IsStat4 || nEqZero==0 );
+
+#ifdef SQLITE_ENABLE_STAT4
+  if( pNew->isPSample==0 ){
+    Stat4Sample *pUpgrade = 0;
+    assert( pNew->anEq[pNew->iCol]>0 );
+
+    /* This sample is being added because the prefix that ends in column 
+    ** iCol occurs many times in the table. However, if we have already
+    ** added a sample that shares this prefix, there is no need to add
+    ** this one. Instead, upgrade the priority of the highest priority
+    ** existing sample that shares this prefix.  */
+    for(i=p->nSample-1; i>=0; i--){
+      Stat4Sample *pOld = &p->a[i];
+      if( pOld->anEq[pNew->iCol]==0 ){
+        if( pOld->isPSample ) return;
+        assert( pOld->iCol>pNew->iCol );
+        assert( sampleIsBetter(p, pNew, pOld) );
+        if( pUpgrade==0 || sampleIsBetter(p, pOld, pUpgrade) ){
+          pUpgrade = pOld;
+        }
+      }
+    }
+    if( pUpgrade ){
+      pUpgrade->iCol = pNew->iCol;
+      pUpgrade->anEq[pUpgrade->iCol] = pNew->anEq[pUpgrade->iCol];
+      goto find_new_min;
+    }
+  }
+#endif
+
+  /* If necessary, remove sample iMin to make room for the new sample. */
+  if( p->nSample>=p->mxSample ){
+    Stat4Sample *pMin = &p->a[p->iMin];
+    tRowcnt *anEq = pMin->anEq;
+    tRowcnt *anLt = pMin->anLt;
+    tRowcnt *anDLt = pMin->anDLt;
+    sampleClear(p->db, pMin);
+    memmove(pMin, &pMin[1], sizeof(p->a[0])*(p->nSample-p->iMin-1));
+    pSample = &p->a[p->nSample-1];
+    pSample->nRowid = 0;
+    pSample->anEq = anEq;
+    pSample->anDLt = anDLt;
+    pSample->anLt = anLt;
+    p->nSample = p->mxSample-1;
+  }
+
+  /* The "rows less-than" for the rowid column must be greater than that
+  ** for the last sample in the p->a[] array. Otherwise, the samples would
+  ** be out of order. */
+#ifdef SQLITE_ENABLE_STAT4
+  assert( p->nSample==0 
+       || pNew->anLt[p->nCol-1] > p->a[p->nSample-1].anLt[p->nCol-1] );
+#endif
+
+  /* Insert the new sample */
+  pSample = &p->a[p->nSample];
+  sampleCopy(p, pSample, pNew);
+  p->nSample++;
+
+  /* Zero the first nEqZero entries in the anEq[] array. */
+  memset(pSample->anEq, 0, sizeof(tRowcnt)*nEqZero);
+
+#ifdef SQLITE_ENABLE_STAT4
+ find_new_min:
+#endif
+  if( p->nSample>=p->mxSample ){
+    int iMin = -1;
+    for(i=0; i<p->mxSample; i++){
+      if( p->a[i].isPSample ) continue;
+      if( iMin<0 || sampleIsBetter(p, &p->a[iMin], &p->a[i]) ){
+        iMin = i;
+      }
+    }
+    assert( iMin>=0 );
+    p->iMin = iMin;
+  }
+}
+#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
+
+/*
+** Field iChng of the index being scanned has changed. So at this point
+** p->current contains a sample that reflects the previous row of the
+** index. The value of anEq[iChng] and subsequent anEq[] elements are
+** correct at this point.
+*/
+static void samplePushPrevious(Stat4Accum *p, int iChng){
+#ifdef SQLITE_ENABLE_STAT4
+  int i;
+
+  /* Check if any samples from the aBest[] array should be pushed
+  ** into IndexSample.a[] at this point.  */
+  for(i=(p->nCol-2); i>=iChng; i--){
+    Stat4Sample *pBest = &p->aBest[i];
+    pBest->anEq[i] = p->current.anEq[i];
+    if( p->nSample<p->mxSample || sampleIsBetter(p, pBest, &p->a[p->iMin]) ){
+      sampleInsert(p, pBest, i);
+    }
+  }
+
+  /* Update the anEq[] fields of any samples already collected. */
+  for(i=p->nSample-1; i>=0; i--){
+    int j;
+    for(j=iChng; j<p->nCol; j++){
+      if( p->a[i].anEq[j]==0 ) p->a[i].anEq[j] = p->current.anEq[j];
+    }
+  }
+#endif
+
+#if defined(SQLITE_ENABLE_STAT3) && !defined(SQLITE_ENABLE_STAT4)
+  if( iChng==0 ){
+    tRowcnt nLt = p->current.anLt[0];
+    tRowcnt nEq = p->current.anEq[0];
+
+    /* Check if this is to be a periodic sample. If so, add it. */
+    if( (nLt/p->nPSample)!=(nLt+nEq)/p->nPSample ){
+      p->current.isPSample = 1;
+      sampleInsert(p, &p->current, 0);
+      p->current.isPSample = 0;
+    }else 
+
+    /* Or if it is a non-periodic sample. Add it in this case too. */
+    if( p->nSample<p->mxSample 
+     || sampleIsBetter(p, &p->current, &p->a[p->iMin]) 
+    ){
+      sampleInsert(p, &p->current, 0);
+    }
+  }
+#endif
+
+#ifndef SQLITE_ENABLE_STAT3_OR_STAT4
+  UNUSED_PARAMETER( p );
+  UNUSED_PARAMETER( iChng );
+#endif
+}
+
+/*
+** Implementation of the stat_push SQL function:  stat_push(P,C,R)
+** Arguments:
+**
+**    P     Pointer to the Stat4Accum object created by stat_init()
+**    C     Index of left-most column to differ from previous row
+**    R     Rowid for the current row.  Might be a key record for
+**          WITHOUT ROWID tables.
+**
+** This SQL function always returns NULL.  It's purpose it to accumulate
+** statistical data and/or samples in the Stat4Accum object about the
+** index being analyzed.  The stat_get() SQL function will later be used to
+** extract relevant information for constructing the sqlite_statN tables.
+**
+** The R parameter is only used for STAT3 and STAT4
+*/
+static void statPush(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  int i;
+
+  /* The three function arguments */
+  Stat4Accum *p = (Stat4Accum*)sqlite3_value_blob(argv[0]);
+  int iChng = sqlite3_value_int(argv[1]);
+
+  UNUSED_PARAMETER( argc );
+  UNUSED_PARAMETER( context );
+  assert( p->nCol>0 );
+  assert( iChng<p->nCol );
+
+  if( p->nRow==0 ){
+    /* This is the first call to this function. Do initialization. */
+    for(i=0; i<p->nCol; i++) p->current.anEq[i] = 1;
+  }else{
+    /* Second and subsequent calls get processed here */
+    samplePushPrevious(p, iChng);
+
+    /* Update anDLt[], anLt[] and anEq[] to reflect the values that apply
+    ** to the current row of the index. */
+    for(i=0; i<iChng; i++){
+      p->current.anEq[i]++;
+    }
+    for(i=iChng; i<p->nCol; i++){
+      p->current.anDLt[i]++;
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+      p->current.anLt[i] += p->current.anEq[i];
+#endif
+      p->current.anEq[i] = 1;
+    }
+  }
+  p->nRow++;
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  if( sqlite3_value_type(argv[2])==SQLITE_INTEGER ){
+    sampleSetRowidInt64(p->db, &p->current, sqlite3_value_int64(argv[2]));
+  }else{
+    sampleSetRowid(p->db, &p->current, sqlite3_value_bytes(argv[2]),
+                                       sqlite3_value_blob(argv[2]));
+  }
+  p->current.iHash = p->iPrn = p->iPrn*1103515245 + 12345;
+#endif
+
+#ifdef SQLITE_ENABLE_STAT4
+  {
+    tRowcnt nLt = p->current.anLt[p->nCol-1];
+
+    /* Check if this is to be a periodic sample. If so, add it. */
+    if( (nLt/p->nPSample)!=(nLt+1)/p->nPSample ){
+      p->current.isPSample = 1;
+      p->current.iCol = 0;
+      sampleInsert(p, &p->current, p->nCol-1);
+      p->current.isPSample = 0;
+    }
+
+    /* Update the aBest[] array. */
+    for(i=0; i<(p->nCol-1); i++){
+      p->current.iCol = i;
+      if( i>=iChng || sampleIsBetterPost(p, &p->current, &p->aBest[i]) ){
+        sampleCopy(p, &p->aBest[i], &p->current);
+      }
+    }
+  }
+#endif
+}
+static const FuncDef statPushFuncdef = {
+  2+IsStat34,      /* nArg */
+  SQLITE_UTF8,     /* funcFlags */
+  0,               /* pUserData */
+  0,               /* pNext */
+  statPush,        /* xSFunc */
+  0,               /* xFinalize */
+  "stat_push",     /* zName */
+  {0}
+};
+
+#define STAT_GET_STAT1 0          /* "stat" column of stat1 table */
+#define STAT_GET_ROWID 1          /* "rowid" column of stat[34] entry */
+#define STAT_GET_NEQ   2          /* "neq" column of stat[34] entry */
+#define STAT_GET_NLT   3          /* "nlt" column of stat[34] entry */
+#define STAT_GET_NDLT  4          /* "ndlt" column of stat[34] entry */
+
+/*
+** Implementation of the stat_get(P,J) SQL function.  This routine is
+** used to query statistical information that has been gathered into
+** the Stat4Accum object by prior calls to stat_push().  The P parameter
+** has type BLOB but it is really just a pointer to the Stat4Accum object.
+** The content to returned is determined by the parameter J
+** which is one of the STAT_GET_xxxx values defined above.
+**
+** If neither STAT3 nor STAT4 are enabled, then J is always
+** STAT_GET_STAT1 and is hence omitted and this routine becomes
+** a one-parameter function, stat_get(P), that always returns the
+** stat1 table entry information.
+*/
+static void statGet(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  Stat4Accum *p = (Stat4Accum*)sqlite3_value_blob(argv[0]);
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  /* STAT3 and STAT4 have a parameter on this routine. */
+  int eCall = sqlite3_value_int(argv[1]);
+  assert( argc==2 );
+  assert( eCall==STAT_GET_STAT1 || eCall==STAT_GET_NEQ 
+       || eCall==STAT_GET_ROWID || eCall==STAT_GET_NLT
+       || eCall==STAT_GET_NDLT 
+  );
+  if( eCall==STAT_GET_STAT1 )
+#else
+  assert( argc==1 );
+#endif
+  {
+    /* Return the value to store in the "stat" column of the sqlite_stat1
+    ** table for this index.
+    **
+    ** The value is a string composed of a list of integers describing 
+    ** the index. The first integer in the list is the total number of 
+    ** entries in the index. There is one additional integer in the list 
+    ** for each indexed column. This additional integer is an estimate of
+    ** the number of rows matched by a stabbing query on the index using
+    ** a key with the corresponding number of fields. In other words,
+    ** if the index is on columns (a,b) and the sqlite_stat1 value is 
+    ** "100 10 2", then SQLite estimates that:
+    **
+    **   * the index contains 100 rows,
+    **   * "WHERE a=?" matches 10 rows, and
+    **   * "WHERE a=? AND b=?" matches 2 rows.
+    **
+    ** If D is the count of distinct values and K is the total number of 
+    ** rows, then each estimate is computed as:
+    **
+    **        I = (K+D-1)/D
+    */
+    char *z;
+    int i;
+
+    char *zRet = sqlite3MallocZero( (p->nKeyCol+1)*25 );
+    if( zRet==0 ){
+      sqlite3_result_error_nomem(context);
+      return;
+    }
+
+    sqlite3_snprintf(24, zRet, "%llu", (u64)p->nRow);
+    z = zRet + sqlite3Strlen30(zRet);
+    for(i=0; i<p->nKeyCol; i++){
+      u64 nDistinct = p->current.anDLt[i] + 1;
+      u64 iVal = (p->nRow + nDistinct - 1) / nDistinct;
+      sqlite3_snprintf(24, z, " %llu", iVal);
+      z += sqlite3Strlen30(z);
+      assert( p->current.anEq[i] );
+    }
+    assert( z[0]=='\0' && z>zRet );
+
+    sqlite3_result_text(context, zRet, -1, sqlite3_free);
+  }
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  else if( eCall==STAT_GET_ROWID ){
+    if( p->iGet<0 ){
+      samplePushPrevious(p, 0);
+      p->iGet = 0;
+    }
+    if( p->iGet<p->nSample ){
+      Stat4Sample *pS = p->a + p->iGet;
+      if( pS->nRowid==0 ){
+        sqlite3_result_int64(context, pS->u.iRowid);
+      }else{
+        sqlite3_result_blob(context, pS->u.aRowid, pS->nRowid,
+                            SQLITE_TRANSIENT);
+      }
+    }
+  }else{
+    tRowcnt *aCnt = 0;
+
+    assert( p->iGet<p->nSample );
+    switch( eCall ){
+      case STAT_GET_NEQ:  aCnt = p->a[p->iGet].anEq; break;
+      case STAT_GET_NLT:  aCnt = p->a[p->iGet].anLt; break;
+      default: {
+        aCnt = p->a[p->iGet].anDLt; 
+        p->iGet++;
+        break;
+      }
+    }
+
+    if( IsStat3 ){
+      sqlite3_result_int64(context, (i64)aCnt[0]);
+    }else{
+      char *zRet = sqlite3MallocZero(p->nCol * 25);
+      if( zRet==0 ){
+        sqlite3_result_error_nomem(context);
+      }else{
+        int i;
+        char *z = zRet;
+        for(i=0; i<p->nCol; i++){
+          sqlite3_snprintf(24, z, "%llu ", (u64)aCnt[i]);
+          z += sqlite3Strlen30(z);
+        }
+        assert( z[0]=='\0' && z>zRet );
+        z[-1] = '\0';
+        sqlite3_result_text(context, zRet, -1, sqlite3_free);
+      }
+    }
+  }
+#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
+#ifndef SQLITE_DEBUG
+  UNUSED_PARAMETER( argc );
+#endif
+}
+static const FuncDef statGetFuncdef = {
+  1+IsStat34,      /* nArg */
+  SQLITE_UTF8,     /* funcFlags */
+  0,               /* pUserData */
+  0,               /* pNext */
+  statGet,         /* xSFunc */
+  0,               /* xFinalize */
+  "stat_get",      /* zName */
+  {0}
+};
+
+static void callStatGet(Vdbe *v, int regStat4, int iParam, int regOut){
+  assert( regOut!=regStat4 && regOut!=regStat4+1 );
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  sqlite3VdbeAddOp2(v, OP_Integer, iParam, regStat4+1);
+#elif SQLITE_DEBUG
+  assert( iParam==STAT_GET_STAT1 );
+#else
+  UNUSED_PARAMETER( iParam );
+#endif
+  sqlite3VdbeAddOp4(v, OP_Function0, 0, regStat4, regOut,
+                    (char*)&statGetFuncdef, P4_FUNCDEF);
+  sqlite3VdbeChangeP5(v, 1 + IsStat34);
+}
+
+/*
+** Generate code to do an analysis of all indices associated with
+** a single table.
+*/
+static void analyzeOneTable(
+  Parse *pParse,   /* Parser context */
+  Table *pTab,     /* Table whose indices are to be analyzed */
+  Index *pOnlyIdx, /* If not NULL, only analyze this one index */
+  int iStatCur,    /* Index of VdbeCursor that writes the sqlite_stat1 table */
+  int iMem,        /* Available memory locations begin here */
+  int iTab         /* Next available cursor */
+){
+  sqlite3 *db = pParse->db;    /* Database handle */
+  Index *pIdx;                 /* An index to being analyzed */
+  int iIdxCur;                 /* Cursor open on index being analyzed */
+  int iTabCur;                 /* Table cursor */
+  Vdbe *v;                     /* The virtual machine being built up */
+  int i;                       /* Loop counter */
+  int jZeroRows = -1;          /* Jump from here if number of rows is zero */
+  int iDb;                     /* Index of database containing pTab */
+  u8 needTableCnt = 1;         /* True to count the table */
+  int regNewRowid = iMem++;    /* Rowid for the inserted record */
+  int regStat4 = iMem++;       /* Register to hold Stat4Accum object */
+  int regChng = iMem++;        /* Index of changed index field */
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  int regRowid = iMem++;       /* Rowid argument passed to stat_push() */
+#endif
+  int regTemp = iMem++;        /* Temporary use register */
+  int regTabname = iMem++;     /* Register containing table name */
+  int regIdxname = iMem++;     /* Register containing index name */
+  int regStat1 = iMem++;       /* Value for the stat column of sqlite_stat1 */
+  int regPrev = iMem;          /* MUST BE LAST (see below) */
+
+  pParse->nMem = MAX(pParse->nMem, iMem);
+  v = sqlite3GetVdbe(pParse);
+  if( v==0 || NEVER(pTab==0) ){
+    return;
+  }
+  if( pTab->tnum==0 ){
+    /* Do not gather statistics on views or virtual tables */
+    return;
+  }
+  if( sqlite3_strlike("sqlite_%", pTab->zName, 0)==0 ){
+    /* Do not gather statistics on system tables */
+    return;
+  }
+  assert( sqlite3BtreeHoldsAllMutexes(db) );
+  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+  assert( iDb>=0 );
+  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  if( sqlite3AuthCheck(pParse, SQLITE_ANALYZE, pTab->zName, 0,
+      db->aDb[iDb].zDbSName ) ){
+    return;
+  }
+#endif
+
+  /* Establish a read-lock on the table at the shared-cache level. 
+  ** Open a read-only cursor on the table. Also allocate a cursor number
+  ** to use for scanning indexes (iIdxCur). No index cursor is opened at
+  ** this time though.  */
+  sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
+  iTabCur = iTab++;
+  iIdxCur = iTab++;
+  pParse->nTab = MAX(pParse->nTab, iTab);
+  sqlite3OpenTable(pParse, iTabCur, iDb, pTab, OP_OpenRead);
+  sqlite3VdbeLoadString(v, regTabname, pTab->zName);
+
+  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+    int nCol;                     /* Number of columns in pIdx. "N" */
+    int addrRewind;               /* Address of "OP_Rewind iIdxCur" */
+    int addrNextRow;              /* Address of "next_row:" */
+    const char *zIdxName;         /* Name of the index */
+    int nColTest;                 /* Number of columns to test for changes */
+
+    if( pOnlyIdx && pOnlyIdx!=pIdx ) continue;
+    if( pIdx->pPartIdxWhere==0 ) needTableCnt = 0;
+    if( !HasRowid(pTab) && IsPrimaryKeyIndex(pIdx) ){
+      nCol = pIdx->nKeyCol;
+      zIdxName = pTab->zName;
+      nColTest = nCol - 1;
+    }else{
+      nCol = pIdx->nColumn;
+      zIdxName = pIdx->zName;
+      nColTest = pIdx->uniqNotNull ? pIdx->nKeyCol-1 : nCol-1;
+    }
+
+    /* Populate the register containing the index name. */
+    sqlite3VdbeLoadString(v, regIdxname, zIdxName);
+    VdbeComment((v, "Analysis for %s.%s", pTab->zName, zIdxName));
+
+    /*
+    ** Pseudo-code for loop that calls stat_push():
+    **
+    **   Rewind csr
+    **   if eof(csr) goto end_of_scan;
+    **   regChng = 0
+    **   goto chng_addr_0;
+    **
+    **  next_row:
+    **   regChng = 0
+    **   if( idx(0) != regPrev(0) ) goto chng_addr_0
+    **   regChng = 1
+    **   if( idx(1) != regPrev(1) ) goto chng_addr_1
+    **   ...
+    **   regChng = N
+    **   goto chng_addr_N
+    **
+    **  chng_addr_0:
+    **   regPrev(0) = idx(0)
+    **  chng_addr_1:
+    **   regPrev(1) = idx(1)
+    **  ...
+    **
+    **  endDistinctTest:
+    **   regRowid = idx(rowid)
+    **   stat_push(P, regChng, regRowid)
+    **   Next csr
+    **   if !eof(csr) goto next_row;
+    **
+    **  end_of_scan:
+    */
+
+    /* Make sure there are enough memory cells allocated to accommodate 
+    ** the regPrev array and a trailing rowid (the rowid slot is required
+    ** when building a record to insert into the sample column of 
+    ** the sqlite_stat4 table.  */
+    pParse->nMem = MAX(pParse->nMem, regPrev+nColTest);
+
+    /* Open a read-only cursor on the index being analyzed. */
+    assert( iDb==sqlite3SchemaToIndex(db, pIdx->pSchema) );
+    sqlite3VdbeAddOp3(v, OP_OpenRead, iIdxCur, pIdx->tnum, iDb);
+    sqlite3VdbeSetP4KeyInfo(pParse, pIdx);
+    VdbeComment((v, "%s", pIdx->zName));
+
+    /* Invoke the stat_init() function. The arguments are:
+    ** 
+    **    (1) the number of columns in the index including the rowid
+    **        (or for a WITHOUT ROWID table, the number of PK columns),
+    **    (2) the number of columns in the key without the rowid/pk
+    **    (3) the number of rows in the index,
+    **
+    **
+    ** The third argument is only used for STAT3 and STAT4
+    */
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+    sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regStat4+3);
+#endif
+    sqlite3VdbeAddOp2(v, OP_Integer, nCol, regStat4+1);
+    sqlite3VdbeAddOp2(v, OP_Integer, pIdx->nKeyCol, regStat4+2);
+    sqlite3VdbeAddOp4(v, OP_Function0, 0, regStat4+1, regStat4,
+                     (char*)&statInitFuncdef, P4_FUNCDEF);
+    sqlite3VdbeChangeP5(v, 2+IsStat34);
+
+    /* Implementation of the following:
+    **
+    **   Rewind csr
+    **   if eof(csr) goto end_of_scan;
+    **   regChng = 0
+    **   goto next_push_0;
+    **
+    */
+    addrRewind = sqlite3VdbeAddOp1(v, OP_Rewind, iIdxCur);
+    VdbeCoverage(v);
+    sqlite3VdbeAddOp2(v, OP_Integer, 0, regChng);
+    addrNextRow = sqlite3VdbeCurrentAddr(v);
+
+    if( nColTest>0 ){
+      int endDistinctTest = sqlite3VdbeMakeLabel(v);
+      int *aGotoChng;               /* Array of jump instruction addresses */
+      aGotoChng = sqlite3DbMallocRawNN(db, sizeof(int)*nColTest);
+      if( aGotoChng==0 ) continue;
+
+      /*
+      **  next_row:
+      **   regChng = 0
+      **   if( idx(0) != regPrev(0) ) goto chng_addr_0
+      **   regChng = 1
+      **   if( idx(1) != regPrev(1) ) goto chng_addr_1
+      **   ...
+      **   regChng = N
+      **   goto endDistinctTest
+      */
+      sqlite3VdbeAddOp0(v, OP_Goto);
+      addrNextRow = sqlite3VdbeCurrentAddr(v);
+      if( nColTest==1 && pIdx->nKeyCol==1 && IsUniqueIndex(pIdx) ){
+        /* For a single-column UNIQUE index, once we have found a non-NULL
+        ** row, we know that all the rest will be distinct, so skip 
+        ** subsequent distinctness tests. */
+        sqlite3VdbeAddOp2(v, OP_NotNull, regPrev, endDistinctTest);
+        VdbeCoverage(v);
+      }
+      for(i=0; i<nColTest; i++){
+        char *pColl = (char*)sqlite3LocateCollSeq(pParse, pIdx->azColl[i]);
+        sqlite3VdbeAddOp2(v, OP_Integer, i, regChng);
+        sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regTemp);
+        aGotoChng[i] = 
+        sqlite3VdbeAddOp4(v, OP_Ne, regTemp, 0, regPrev+i, pColl, P4_COLLSEQ);
+        sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
+        VdbeCoverage(v);
+      }
+      sqlite3VdbeAddOp2(v, OP_Integer, nColTest, regChng);
+      sqlite3VdbeGoto(v, endDistinctTest);
+  
+  
+      /*
+      **  chng_addr_0:
+      **   regPrev(0) = idx(0)
+      **  chng_addr_1:
+      **   regPrev(1) = idx(1)
+      **  ...
+      */
+      sqlite3VdbeJumpHere(v, addrNextRow-1);
+      for(i=0; i<nColTest; i++){
+        sqlite3VdbeJumpHere(v, aGotoChng[i]);
+        sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regPrev+i);
+      }
+      sqlite3VdbeResolveLabel(v, endDistinctTest);
+      sqlite3DbFree(db, aGotoChng);
+    }
+  
+    /*
+    **  chng_addr_N:
+    **   regRowid = idx(rowid)            // STAT34 only
+    **   stat_push(P, regChng, regRowid)  // 3rd parameter STAT34 only
+    **   Next csr
+    **   if !eof(csr) goto next_row;
+    */
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+    assert( regRowid==(regStat4+2) );
+    if( HasRowid(pTab) ){
+      sqlite3VdbeAddOp2(v, OP_IdxRowid, iIdxCur, regRowid);
+    }else{
+      Index *pPk = sqlite3PrimaryKeyIndex(pIdx->pTable);
+      int j, k, regKey;
+      regKey = sqlite3GetTempRange(pParse, pPk->nKeyCol);
+      for(j=0; j<pPk->nKeyCol; j++){
+        k = sqlite3ColumnOfIndex(pIdx, pPk->aiColumn[j]);
+        assert( k>=0 && k<pTab->nCol );
+        sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, k, regKey+j);
+        VdbeComment((v, "%s", pTab->aCol[pPk->aiColumn[j]].zName));
+      }
+      sqlite3VdbeAddOp3(v, OP_MakeRecord, regKey, pPk->nKeyCol, regRowid);
+      sqlite3ReleaseTempRange(pParse, regKey, pPk->nKeyCol);
+    }
+#endif
+    assert( regChng==(regStat4+1) );
+    sqlite3VdbeAddOp4(v, OP_Function0, 1, regStat4, regTemp,
+                     (char*)&statPushFuncdef, P4_FUNCDEF);
+    sqlite3VdbeChangeP5(v, 2+IsStat34);
+    sqlite3VdbeAddOp2(v, OP_Next, iIdxCur, addrNextRow); VdbeCoverage(v);
+
+    /* Add the entry to the stat1 table. */
+    callStatGet(v, regStat4, STAT_GET_STAT1, regStat1);
+    assert( "BBB"[0]==SQLITE_AFF_TEXT );
+    sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regTemp, "BBB", 0);
+    sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regNewRowid);
+    sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regTemp, regNewRowid);
+    sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
+
+    /* Add the entries to the stat3 or stat4 table. */
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+    {
+      int regEq = regStat1;
+      int regLt = regStat1+1;
+      int regDLt = regStat1+2;
+      int regSample = regStat1+3;
+      int regCol = regStat1+4;
+      int regSampleRowid = regCol + nCol;
+      int addrNext;
+      int addrIsNull;
+      u8 seekOp = HasRowid(pTab) ? OP_NotExists : OP_NotFound;
+
+      pParse->nMem = MAX(pParse->nMem, regCol+nCol);
+
+      addrNext = sqlite3VdbeCurrentAddr(v);
+      callStatGet(v, regStat4, STAT_GET_ROWID, regSampleRowid);
+      addrIsNull = sqlite3VdbeAddOp1(v, OP_IsNull, regSampleRowid);
+      VdbeCoverage(v);
+      callStatGet(v, regStat4, STAT_GET_NEQ, regEq);
+      callStatGet(v, regStat4, STAT_GET_NLT, regLt);
+      callStatGet(v, regStat4, STAT_GET_NDLT, regDLt);
+      sqlite3VdbeAddOp4Int(v, seekOp, iTabCur, addrNext, regSampleRowid, 0);
+      /* We know that the regSampleRowid row exists because it was read by
+      ** the previous loop.  Thus the not-found jump of seekOp will never
+      ** be taken */
+      VdbeCoverageNeverTaken(v);
+#ifdef SQLITE_ENABLE_STAT3
+      sqlite3ExprCodeLoadIndexColumn(pParse, pIdx, iTabCur, 0, regSample);
+#else
+      for(i=0; i<nCol; i++){
+        sqlite3ExprCodeLoadIndexColumn(pParse, pIdx, iTabCur, i, regCol+i);
+      }
+      sqlite3VdbeAddOp3(v, OP_MakeRecord, regCol, nCol, regSample);
+#endif
+      sqlite3VdbeAddOp3(v, OP_MakeRecord, regTabname, 6, regTemp);
+      sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur+1, regNewRowid);
+      sqlite3VdbeAddOp3(v, OP_Insert, iStatCur+1, regTemp, regNewRowid);
+      sqlite3VdbeAddOp2(v, OP_Goto, 1, addrNext); /* P1==1 for end-of-loop */
+      sqlite3VdbeJumpHere(v, addrIsNull);
+    }
+#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
+
+    /* End of analysis */
+    sqlite3VdbeJumpHere(v, addrRewind);
+  }
+
+
+  /* Create a single sqlite_stat1 entry containing NULL as the index
+  ** name and the row count as the content.
+  */
+  if( pOnlyIdx==0 && needTableCnt ){
+    VdbeComment((v, "%s", pTab->zName));
+    sqlite3VdbeAddOp2(v, OP_Count, iTabCur, regStat1);
+    jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, regStat1); VdbeCoverage(v);
+    sqlite3VdbeAddOp2(v, OP_Null, 0, regIdxname);
+    assert( "BBB"[0]==SQLITE_AFF_TEXT );
+    sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regTemp, "BBB", 0);
+    sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regNewRowid);
+    sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regTemp, regNewRowid);
+    sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
+    sqlite3VdbeJumpHere(v, jZeroRows);
+  }
+}
+
+
+/*
+** Generate code that will cause the most recent index analysis to
+** be loaded into internal hash tables where is can be used.
+*/
+static void loadAnalysis(Parse *pParse, int iDb){
+  Vdbe *v = sqlite3GetVdbe(pParse);
+  if( v ){
+    sqlite3VdbeAddOp1(v, OP_LoadAnalysis, iDb);
+  }
+}
+
+/*
+** Generate code that will do an analysis of an entire database
+*/
+static void analyzeDatabase(Parse *pParse, int iDb){
+  sqlite3 *db = pParse->db;
+  Schema *pSchema = db->aDb[iDb].pSchema;    /* Schema of database iDb */
+  HashElem *k;
+  int iStatCur;
+  int iMem;
+  int iTab;
+
+  sqlite3BeginWriteOperation(pParse, 0, iDb);
+  iStatCur = pParse->nTab;
+  pParse->nTab += 3;
+  openStatTable(pParse, iDb, iStatCur, 0, 0);
+  iMem = pParse->nMem+1;
+  iTab = pParse->nTab;
+  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+  for(k=sqliteHashFirst(&pSchema->tblHash); k; k=sqliteHashNext(k)){
+    Table *pTab = (Table*)sqliteHashData(k);
+    analyzeOneTable(pParse, pTab, 0, iStatCur, iMem, iTab);
+  }
+  loadAnalysis(pParse, iDb);
+}
+
+/*
+** Generate code that will do an analysis of a single table in
+** a database.  If pOnlyIdx is not NULL then it is a single index
+** in pTab that should be analyzed.
+*/
+static void analyzeTable(Parse *pParse, Table *pTab, Index *pOnlyIdx){
+  int iDb;
+  int iStatCur;
+
+  assert( pTab!=0 );
+  assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
+  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
+  sqlite3BeginWriteOperation(pParse, 0, iDb);
+  iStatCur = pParse->nTab;
+  pParse->nTab += 3;
+  if( pOnlyIdx ){
+    openStatTable(pParse, iDb, iStatCur, pOnlyIdx->zName, "idx");
+  }else{
+    openStatTable(pParse, iDb, iStatCur, pTab->zName, "tbl");
+  }
+  analyzeOneTable(pParse, pTab, pOnlyIdx, iStatCur,pParse->nMem+1,pParse->nTab);
+  loadAnalysis(pParse, iDb);
+}
+
+/*
+** Generate code for the ANALYZE command.  The parser calls this routine
+** when it recognizes an ANALYZE command.
+**
+**        ANALYZE                            -- 1
+**        ANALYZE  <database>                -- 2
+**        ANALYZE  ?<database>.?<tablename>  -- 3
+**
+** Form 1 causes all indices in all attached databases to be analyzed.
+** Form 2 analyzes all indices the single database named.
+** Form 3 analyzes all indices associated with the named table.
+*/
+SQLITE_PRIVATE void sqlite3Analyze(Parse *pParse, Token *pName1, Token *pName2){
+  sqlite3 *db = pParse->db;
+  int iDb;
+  int i;
+  char *z, *zDb;
+  Table *pTab;
+  Index *pIdx;
+  Token *pTableName;
+  Vdbe *v;
+
+  /* Read the database schema. If an error occurs, leave an error message
+  ** and code in pParse and return NULL. */
+  assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
+  if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
+    return;
+  }
+
+  assert( pName2!=0 || pName1==0 );
+  if( pName1==0 ){
+    /* Form 1:  Analyze everything */
+    for(i=0; i<db->nDb; i++){
+      if( i==1 ) continue;  /* Do not analyze the TEMP database */
+      analyzeDatabase(pParse, i);
+    }
+  }else if( pName2->n==0 ){
+    /* Form 2:  Analyze the database or table named */
+    iDb = sqlite3FindDb(db, pName1);
+    if( iDb>=0 ){
+      analyzeDatabase(pParse, iDb);
+    }else{
+      z = sqlite3NameFromToken(db, pName1);
+      if( z ){
+        if( (pIdx = sqlite3FindIndex(db, z, 0))!=0 ){
+          analyzeTable(pParse, pIdx->pTable, pIdx);
+        }else if( (pTab = sqlite3LocateTable(pParse, 0, z, 0))!=0 ){
+          analyzeTable(pParse, pTab, 0);
+        }
+        sqlite3DbFree(db, z);
+      }
+    }
+  }else{
+    /* Form 3: Analyze the fully qualified table name */
+    iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pTableName);
+    if( iDb>=0 ){
+      zDb = db->aDb[iDb].zDbSName;
+      z = sqlite3NameFromToken(db, pTableName);
+      if( z ){
+        if( (pIdx = sqlite3FindIndex(db, z, zDb))!=0 ){
+          analyzeTable(pParse, pIdx->pTable, pIdx);
+        }else if( (pTab = sqlite3LocateTable(pParse, 0, z, zDb))!=0 ){
+          analyzeTable(pParse, pTab, 0);
+        }
+        sqlite3DbFree(db, z);
+      }
+    }   
+  }
+  v = sqlite3GetVdbe(pParse);
+  if( v ) sqlite3VdbeAddOp0(v, OP_Expire);
+}
+
+/*
+** Used to pass information from the analyzer reader through to the
+** callback routine.
+*/
+typedef struct analysisInfo analysisInfo;
+struct analysisInfo {
+  sqlite3 *db;
+  const char *zDatabase;
+};
+
+/*
+** The first argument points to a nul-terminated string containing a
+** list of space separated integers. Read the first nOut of these into
+** the array aOut[].
+*/
+static void decodeIntArray(
+  char *zIntArray,       /* String containing int array to decode */
+  int nOut,              /* Number of slots in aOut[] */
+  tRowcnt *aOut,         /* Store integers here */
+  LogEst *aLog,          /* Or, if aOut==0, here */
+  Index *pIndex          /* Handle extra flags for this index, if not NULL */
+){
+  char *z = zIntArray;
+  int c;
+  int i;
+  tRowcnt v;
+
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  if( z==0 ) z = "";
+#else
+  assert( z!=0 );
+#endif
+  for(i=0; *z && i<nOut; i++){
+    v = 0;
+    while( (c=z[0])>='0' && c<='9' ){
+      v = v*10 + c - '0';
+      z++;
+    }
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+    if( aOut ) aOut[i] = v;
+    if( aLog ) aLog[i] = sqlite3LogEst(v);
+#else
+    assert( aOut==0 );
+    UNUSED_PARAMETER(aOut);
+    assert( aLog!=0 );
+    aLog[i] = sqlite3LogEst(v);
+#endif
+    if( *z==' ' ) z++;
+  }
+#ifndef SQLITE_ENABLE_STAT3_OR_STAT4
+  assert( pIndex!=0 ); {
+#else
+  if( pIndex ){
+#endif
+    pIndex->bUnordered = 0;
+    pIndex->noSkipScan = 0;
+    while( z[0] ){
+      if( sqlite3_strglob("unordered*", z)==0 ){
+        pIndex->bUnordered = 1;
+      }else if( sqlite3_strglob("sz=[0-9]*", z)==0 ){
+        pIndex->szIdxRow = sqlite3LogEst(sqlite3Atoi(z+3));
+      }else if( sqlite3_strglob("noskipscan*", z)==0 ){
+        pIndex->noSkipScan = 1;
+      }
+#ifdef SQLITE_ENABLE_COSTMULT
+      else if( sqlite3_strglob("costmult=[0-9]*",z)==0 ){
+        pIndex->pTable->costMult = sqlite3LogEst(sqlite3Atoi(z+9));
+      }
+#endif
+      while( z[0]!=0 && z[0]!=' ' ) z++;
+      while( z[0]==' ' ) z++;
+    }
+  }
+}
+
+/*
+** This callback is invoked once for each index when reading the
+** sqlite_stat1 table.  
+**
+**     argv[0] = name of the table
+**     argv[1] = name of the index (might be NULL)
+**     argv[2] = results of analysis - on integer for each column
+**
+** Entries for which argv[1]==NULL simply record the number of rows in
+** the table.
+*/
+static int analysisLoader(void *pData, int argc, char **argv, char **NotUsed){
+  analysisInfo *pInfo = (analysisInfo*)pData;
+  Index *pIndex;
+  Table *pTable;
+  const char *z;
+
+  assert( argc==3 );
+  UNUSED_PARAMETER2(NotUsed, argc);
+
+  if( argv==0 || argv[0]==0 || argv[2]==0 ){
+    return 0;
+  }
+  pTable = sqlite3FindTable(pInfo->db, argv[0], pInfo->zDatabase);
+  if( pTable==0 ){
+    return 0;
+  }
+  if( argv[1]==0 ){
+    pIndex = 0;
+  }else if( sqlite3_stricmp(argv[0],argv[1])==0 ){
+    pIndex = sqlite3PrimaryKeyIndex(pTable);
+  }else{
+    pIndex = sqlite3FindIndex(pInfo->db, argv[1], pInfo->zDatabase);
+  }
+  z = argv[2];
+
+  if( pIndex ){
+    tRowcnt *aiRowEst = 0;
+    int nCol = pIndex->nKeyCol+1;
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+    /* Index.aiRowEst may already be set here if there are duplicate 
+    ** sqlite_stat1 entries for this index. In that case just clobber
+    ** the old data with the new instead of allocating a new array.  */
+    if( pIndex->aiRowEst==0 ){
+      pIndex->aiRowEst = (tRowcnt*)sqlite3MallocZero(sizeof(tRowcnt) * nCol);
+      if( pIndex->aiRowEst==0 ) sqlite3OomFault(pInfo->db);
+    }
+    aiRowEst = pIndex->aiRowEst;
+#endif
+    pIndex->bUnordered = 0;
+    decodeIntArray((char*)z, nCol, aiRowEst, pIndex->aiRowLogEst, pIndex);
+    if( pIndex->pPartIdxWhere==0 ) pTable->nRowLogEst = pIndex->aiRowLogEst[0];
+  }else{
+    Index fakeIdx;
+    fakeIdx.szIdxRow = pTable->szTabRow;
+#ifdef SQLITE_ENABLE_COSTMULT
+    fakeIdx.pTable = pTable;
+#endif
+    decodeIntArray((char*)z, 1, 0, &pTable->nRowLogEst, &fakeIdx);
+    pTable->szTabRow = fakeIdx.szIdxRow;
+  }
+
+  return 0;
+}
+
+/*
+** If the Index.aSample variable is not NULL, delete the aSample[] array
+** and its contents.
+*/
+SQLITE_PRIVATE void sqlite3DeleteIndexSamples(sqlite3 *db, Index *pIdx){
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  if( pIdx->aSample ){
+    int j;
+    for(j=0; j<pIdx->nSample; j++){
+      IndexSample *p = &pIdx->aSample[j];
+      sqlite3DbFree(db, p->p);
+    }
+    sqlite3DbFree(db, pIdx->aSample);
+  }
+  if( db && db->pnBytesFreed==0 ){
+    pIdx->nSample = 0;
+    pIdx->aSample = 0;
+  }
+#else
+  UNUSED_PARAMETER(db);
+  UNUSED_PARAMETER(pIdx);
+#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
+}
+
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+/*
+** Populate the pIdx->aAvgEq[] array based on the samples currently
+** stored in pIdx->aSample[]. 
+*/
+static void initAvgEq(Index *pIdx){
+  if( pIdx ){
+    IndexSample *aSample = pIdx->aSample;
+    IndexSample *pFinal = &aSample[pIdx->nSample-1];
+    int iCol;
+    int nCol = 1;
+    if( pIdx->nSampleCol>1 ){
+      /* If this is stat4 data, then calculate aAvgEq[] values for all
+      ** sample columns except the last. The last is always set to 1, as
+      ** once the trailing PK fields are considered all index keys are
+      ** unique.  */
+      nCol = pIdx->nSampleCol-1;
+      pIdx->aAvgEq[nCol] = 1;
+    }
+    for(iCol=0; iCol<nCol; iCol++){
+      int nSample = pIdx->nSample;
+      int i;                    /* Used to iterate through samples */
+      tRowcnt sumEq = 0;        /* Sum of the nEq values */
+      tRowcnt avgEq = 0;
+      tRowcnt nRow;             /* Number of rows in index */
+      i64 nSum100 = 0;          /* Number of terms contributing to sumEq */
+      i64 nDist100;             /* Number of distinct values in index */
+
+      if( !pIdx->aiRowEst || iCol>=pIdx->nKeyCol || pIdx->aiRowEst[iCol+1]==0 ){
+        nRow = pFinal->anLt[iCol];
+        nDist100 = (i64)100 * pFinal->anDLt[iCol];
+        nSample--;
+      }else{
+        nRow = pIdx->aiRowEst[0];
+        nDist100 = ((i64)100 * pIdx->aiRowEst[0]) / pIdx->aiRowEst[iCol+1];
+      }
+      pIdx->nRowEst0 = nRow;
+
+      /* Set nSum to the number of distinct (iCol+1) field prefixes that
+      ** occur in the stat4 table for this index. Set sumEq to the sum of 
+      ** the nEq values for column iCol for the same set (adding the value 
+      ** only once where there exist duplicate prefixes).  */
+      for(i=0; i<nSample; i++){
+        if( i==(pIdx->nSample-1)
+         || aSample[i].anDLt[iCol]!=aSample[i+1].anDLt[iCol] 
+        ){
+          sumEq += aSample[i].anEq[iCol];
+          nSum100 += 100;
+        }
+      }
+
+      if( nDist100>nSum100 ){
+        avgEq = ((i64)100 * (nRow - sumEq))/(nDist100 - nSum100);
+      }
+      if( avgEq==0 ) avgEq = 1;
+      pIdx->aAvgEq[iCol] = avgEq;
+    }
+  }
+}
+
+/*
+** Look up an index by name.  Or, if the name of a WITHOUT ROWID table
+** is supplied instead, find the PRIMARY KEY index for that table.
+*/
+static Index *findIndexOrPrimaryKey(
+  sqlite3 *db,
+  const char *zName,
+  const char *zDb
+){
+  Index *pIdx = sqlite3FindIndex(db, zName, zDb);
+  if( pIdx==0 ){
+    Table *pTab = sqlite3FindTable(db, zName, zDb);
+    if( pTab && !HasRowid(pTab) ) pIdx = sqlite3PrimaryKeyIndex(pTab);
+  }
+  return pIdx;
+}
+
+/*
+** Load the content from either the sqlite_stat4 or sqlite_stat3 table 
+** into the relevant Index.aSample[] arrays.
+**
+** Arguments zSql1 and zSql2 must point to SQL statements that return
+** data equivalent to the following (statements are different for stat3,
+** see the caller of this function for details):
+**
+**    zSql1: SELECT idx,count(*) FROM %Q.sqlite_stat4 GROUP BY idx
+**    zSql2: SELECT idx,neq,nlt,ndlt,sample FROM %Q.sqlite_stat4
+**
+** where %Q is replaced with the database name before the SQL is executed.
+*/
+static int loadStatTbl(
+  sqlite3 *db,                  /* Database handle */
+  int bStat3,                   /* Assume single column records only */
+  const char *zSql1,            /* SQL statement 1 (see above) */
+  const char *zSql2,            /* SQL statement 2 (see above) */
+  const char *zDb               /* Database name (e.g. "main") */
+){
+  int rc;                       /* Result codes from subroutines */
+  sqlite3_stmt *pStmt = 0;      /* An SQL statement being run */
+  char *zSql;                   /* Text of the SQL statement */
+  Index *pPrevIdx = 0;          /* Previous index in the loop */
+  IndexSample *pSample;         /* A slot in pIdx->aSample[] */
+
+  assert( db->lookaside.bDisable );
+  zSql = sqlite3MPrintf(db, zSql1, zDb);
+  if( !zSql ){
+    return SQLITE_NOMEM_BKPT;
+  }
+  rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
+  sqlite3DbFree(db, zSql);
+  if( rc ) return rc;
+
+  while( sqlite3_step(pStmt)==SQLITE_ROW ){
+    int nIdxCol = 1;              /* Number of columns in stat4 records */
+
+    char *zIndex;   /* Index name */
+    Index *pIdx;    /* Pointer to the index object */
+    int nSample;    /* Number of samples */
+    int nByte;      /* Bytes of space required */
+    int i;          /* Bytes of space required */
+    tRowcnt *pSpace;
+
+    zIndex = (char *)sqlite3_column_text(pStmt, 0);
+    if( zIndex==0 ) continue;
+    nSample = sqlite3_column_int(pStmt, 1);
+    pIdx = findIndexOrPrimaryKey(db, zIndex, zDb);
+    assert( pIdx==0 || bStat3 || pIdx->nSample==0 );
+    /* Index.nSample is non-zero at this point if data has already been
+    ** loaded from the stat4 table. In this case ignore stat3 data.  */
+    if( pIdx==0 || pIdx->nSample ) continue;
+    if( bStat3==0 ){
+      assert( !HasRowid(pIdx->pTable) || pIdx->nColumn==pIdx->nKeyCol+1 );
+      if( !HasRowid(pIdx->pTable) && IsPrimaryKeyIndex(pIdx) ){
+        nIdxCol = pIdx->nKeyCol;
+      }else{
+        nIdxCol = pIdx->nColumn;
+      }
+    }
+    pIdx->nSampleCol = nIdxCol;
+    nByte = sizeof(IndexSample) * nSample;
+    nByte += sizeof(tRowcnt) * nIdxCol * 3 * nSample;
+    nByte += nIdxCol * sizeof(tRowcnt);     /* Space for Index.aAvgEq[] */
+
+    pIdx->aSample = sqlite3DbMallocZero(db, nByte);
+    if( pIdx->aSample==0 ){
+      sqlite3_finalize(pStmt);
+      return SQLITE_NOMEM_BKPT;
+    }
+    pSpace = (tRowcnt*)&pIdx->aSample[nSample];
+    pIdx->aAvgEq = pSpace; pSpace += nIdxCol;
+    for(i=0; i<nSample; i++){
+      pIdx->aSample[i].anEq = pSpace; pSpace += nIdxCol;
+      pIdx->aSample[i].anLt = pSpace; pSpace += nIdxCol;
+      pIdx->aSample[i].anDLt = pSpace; pSpace += nIdxCol;
+    }
+    assert( ((u8*)pSpace)-nByte==(u8*)(pIdx->aSample) );
+  }
+  rc = sqlite3_finalize(pStmt);
+  if( rc ) return rc;
+
+  zSql = sqlite3MPrintf(db, zSql2, zDb);
+  if( !zSql ){
+    return SQLITE_NOMEM_BKPT;
+  }
+  rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
+  sqlite3DbFree(db, zSql);
+  if( rc ) return rc;
+
+  while( sqlite3_step(pStmt)==SQLITE_ROW ){
+    char *zIndex;                 /* Index name */
+    Index *pIdx;                  /* Pointer to the index object */
+    int nCol = 1;                 /* Number of columns in index */
+
+    zIndex = (char *)sqlite3_column_text(pStmt, 0);
+    if( zIndex==0 ) continue;
+    pIdx = findIndexOrPrimaryKey(db, zIndex, zDb);
+    if( pIdx==0 ) continue;
+    /* This next condition is true if data has already been loaded from 
+    ** the sqlite_stat4 table. In this case ignore stat3 data.  */
+    nCol = pIdx->nSampleCol;
+    if( bStat3 && nCol>1 ) continue;
+    if( pIdx!=pPrevIdx ){
+      initAvgEq(pPrevIdx);
+      pPrevIdx = pIdx;
+    }
+    pSample = &pIdx->aSample[pIdx->nSample];
+    decodeIntArray((char*)sqlite3_column_text(pStmt,1),nCol,pSample->anEq,0,0);
+    decodeIntArray((char*)sqlite3_column_text(pStmt,2),nCol,pSample->anLt,0,0);
+    decodeIntArray((char*)sqlite3_column_text(pStmt,3),nCol,pSample->anDLt,0,0);
+
+    /* Take a copy of the sample. Add two 0x00 bytes the end of the buffer.
+    ** This is in case the sample record is corrupted. In that case, the
+    ** sqlite3VdbeRecordCompare() may read up to two varints past the
+    ** end of the allocated buffer before it realizes it is dealing with
+    ** a corrupt record. Adding the two 0x00 bytes prevents this from causing
+    ** a buffer overread.  */
+    pSample->n = sqlite3_column_bytes(pStmt, 4);
+    pSample->p = sqlite3DbMallocZero(db, pSample->n + 2);
+    if( pSample->p==0 ){
+      sqlite3_finalize(pStmt);
+      return SQLITE_NOMEM_BKPT;
+    }
+    memcpy(pSample->p, sqlite3_column_blob(pStmt, 4), pSample->n);
+    pIdx->nSample++;
+  }
+  rc = sqlite3_finalize(pStmt);
+  if( rc==SQLITE_OK ) initAvgEq(pPrevIdx);
+  return rc;
+}
+
+/*
+** Load content from the sqlite_stat4 and sqlite_stat3 tables into 
+** the Index.aSample[] arrays of all indices.
+*/
+static int loadStat4(sqlite3 *db, const char *zDb){
+  int rc = SQLITE_OK;             /* Result codes from subroutines */
+
+  assert( db->lookaside.bDisable );
+  if( sqlite3FindTable(db, "sqlite_stat4", zDb) ){
+    rc = loadStatTbl(db, 0,
+      "SELECT idx,count(*) FROM %Q.sqlite_stat4 GROUP BY idx", 
+      "SELECT idx,neq,nlt,ndlt,sample FROM %Q.sqlite_stat4",
+      zDb
+    );
+  }
+
+  if( rc==SQLITE_OK && sqlite3FindTable(db, "sqlite_stat3", zDb) ){
+    rc = loadStatTbl(db, 1,
+      "SELECT idx,count(*) FROM %Q.sqlite_stat3 GROUP BY idx", 
+      "SELECT idx,neq,nlt,ndlt,sqlite_record(sample) FROM %Q.sqlite_stat3",
+      zDb
+    );
+  }
+
+  return rc;
+}
+#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
+
+/*
+** Load the content of the sqlite_stat1 and sqlite_stat3/4 tables. The
+** contents of sqlite_stat1 are used to populate the Index.aiRowEst[]
+** arrays. The contents of sqlite_stat3/4 are used to populate the
+** Index.aSample[] arrays.
+**
+** If the sqlite_stat1 table is not present in the database, SQLITE_ERROR
+** is returned. In this case, even if SQLITE_ENABLE_STAT3/4 was defined 
+** during compilation and the sqlite_stat3/4 table is present, no data is 
+** read from it.
+**
+** If SQLITE_ENABLE_STAT3/4 was defined during compilation and the 
+** sqlite_stat4 table is not present in the database, SQLITE_ERROR is
+** returned. However, in this case, data is read from the sqlite_stat1
+** table (if it is present) before returning.
+**
+** If an OOM error occurs, this function always sets db->mallocFailed.
+** This means if the caller does not care about other errors, the return
+** code may be ignored.
+*/
+SQLITE_PRIVATE int sqlite3AnalysisLoad(sqlite3 *db, int iDb){
+  analysisInfo sInfo;
+  HashElem *i;
+  char *zSql;
+  int rc = SQLITE_OK;
+
+  assert( iDb>=0 && iDb<db->nDb );
+  assert( db->aDb[iDb].pBt!=0 );
+
+  /* Clear any prior statistics */
+  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+  for(i=sqliteHashFirst(&db->aDb[iDb].pSchema->idxHash);i;i=sqliteHashNext(i)){
+    Index *pIdx = sqliteHashData(i);
+    pIdx->aiRowLogEst[0] = 0;
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+    sqlite3DeleteIndexSamples(db, pIdx);
+    pIdx->aSample = 0;
+#endif
+  }
+
+  /* Load new statistics out of the sqlite_stat1 table */
+  sInfo.db = db;
+  sInfo.zDatabase = db->aDb[iDb].zDbSName;
+  if( sqlite3FindTable(db, "sqlite_stat1", sInfo.zDatabase)!=0 ){
+    zSql = sqlite3MPrintf(db, 
+        "SELECT tbl,idx,stat FROM %Q.sqlite_stat1", sInfo.zDatabase);
+    if( zSql==0 ){
+      rc = SQLITE_NOMEM_BKPT;
+    }else{
+      rc = sqlite3_exec(db, zSql, analysisLoader, &sInfo, 0);
+      sqlite3DbFree(db, zSql);
+    }
+  }
+
+  /* Set appropriate defaults on all indexes not in the sqlite_stat1 table */
+  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+  for(i=sqliteHashFirst(&db->aDb[iDb].pSchema->idxHash);i;i=sqliteHashNext(i)){
+    Index *pIdx = sqliteHashData(i);
+    if( pIdx->aiRowLogEst[0]==0 ) sqlite3DefaultRowEst(pIdx);
+  }
+
+  /* Load the statistics from the sqlite_stat4 table. */
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  if( rc==SQLITE_OK && OptimizationEnabled(db, SQLITE_Stat34) ){
+    db->lookaside.bDisable++;
+    rc = loadStat4(db, sInfo.zDatabase);
+    db->lookaside.bDisable--;
+  }
+  for(i=sqliteHashFirst(&db->aDb[iDb].pSchema->idxHash);i;i=sqliteHashNext(i)){
+    Index *pIdx = sqliteHashData(i);
+    sqlite3_free(pIdx->aiRowEst);
+    pIdx->aiRowEst = 0;
+  }
+#endif
+
+  if( rc==SQLITE_NOMEM ){
+    sqlite3OomFault(db);
+  }
+  return rc;
+}
+
+
+#endif /* SQLITE_OMIT_ANALYZE */
+
+/************** End of analyze.c *********************************************/
+/************** Begin file attach.c ******************************************/
+/*
+** 2003 April 6
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains code used to implement the ATTACH and DETACH commands.
+*/
+/* #include "sqliteInt.h" */
+
+#ifndef SQLITE_OMIT_ATTACH
+/*
+** Resolve an expression that was part of an ATTACH or DETACH statement. This
+** is slightly different from resolving a normal SQL expression, because simple
+** identifiers are treated as strings, not possible column names or aliases.
+**
+** i.e. if the parser sees:
+**
+**     ATTACH DATABASE abc AS def
+**
+** it treats the two expressions as literal strings 'abc' and 'def' instead of
+** looking for columns of the same name.
+**
+** This only applies to the root node of pExpr, so the statement:
+**
+**     ATTACH DATABASE abc||def AS 'db2'
+**
+** will fail because neither abc or def can be resolved.
+*/
+static int resolveAttachExpr(NameContext *pName, Expr *pExpr)
+{
+  int rc = SQLITE_OK;
+  if( pExpr ){
+    if( pExpr->op!=TK_ID ){
+      rc = sqlite3ResolveExprNames(pName, pExpr);
+    }else{
+      pExpr->op = TK_STRING;
+    }
+  }
+  return rc;
+}
+
+/*
+** An SQL user-function registered to do the work of an ATTACH statement. The
+** three arguments to the function come directly from an attach statement:
+**
+**     ATTACH DATABASE x AS y KEY z
+**
+**     SELECT sqlite_attach(x, y, z)
+**
+** If the optional "KEY z" syntax is omitted, an SQL NULL is passed as the
+** third argument.
+*/
+static void attachFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **argv
+){
+  int i;
+  int rc = 0;
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  const char *zName;
+  const char *zFile;
+  char *zPath = 0;
+  char *zErr = 0;
+  unsigned int flags;
+  Db *aNew;
+  char *zErrDyn = 0;
+  sqlite3_vfs *pVfs;
+
+  UNUSED_PARAMETER(NotUsed);
+
+  zFile = (const char *)sqlite3_value_text(argv[0]);
+  zName = (const char *)sqlite3_value_text(argv[1]);
+  if( zFile==0 ) zFile = "";
+  if( zName==0 ) zName = "";
+
+  /* Check for the following errors:
+  **
+  **     * Too many attached databases,
+  **     * Transaction currently open
+  **     * Specified database name already being used.
+  */
+  if( db->nDb>=db->aLimit[SQLITE_LIMIT_ATTACHED]+2 ){
+    zErrDyn = sqlite3MPrintf(db, "too many attached databases - max %d", 
+      db->aLimit[SQLITE_LIMIT_ATTACHED]
+    );
+    goto attach_error;
+  }
+  if( !db->autoCommit ){
+    zErrDyn = sqlite3MPrintf(db, "cannot ATTACH database within transaction");
+    goto attach_error;
+  }
+  for(i=0; i<db->nDb; i++){
+    char *z = db->aDb[i].zDbSName;
+    assert( z && zName );
+    if( sqlite3StrICmp(z, zName)==0 ){
+      zErrDyn = sqlite3MPrintf(db, "database %s is already in use", zName);
+      goto attach_error;
+    }
+  }
+
+  /* Allocate the new entry in the db->aDb[] array and initialize the schema
+  ** hash tables.
+  */
+  if( db->aDb==db->aDbStatic ){
+    aNew = sqlite3DbMallocRawNN(db, sizeof(db->aDb[0])*3 );
+    if( aNew==0 ) return;
+    memcpy(aNew, db->aDb, sizeof(db->aDb[0])*2);
+  }else{
+    aNew = sqlite3DbRealloc(db, db->aDb, sizeof(db->aDb[0])*(db->nDb+1) );
+    if( aNew==0 ) return;
+  }
+  db->aDb = aNew;
+  aNew = &db->aDb[db->nDb];
+  memset(aNew, 0, sizeof(*aNew));
+
+  /* Open the database file. If the btree is successfully opened, use
+  ** it to obtain the database schema. At this point the schema may
+  ** or may not be initialized.
+  */
+  flags = db->openFlags;
+  rc = sqlite3ParseUri(db->pVfs->zName, zFile, &flags, &pVfs, &zPath, &zErr);
+  if( rc!=SQLITE_OK ){
+    if( rc==SQLITE_NOMEM ) sqlite3OomFault(db);
+    sqlite3_result_error(context, zErr, -1);
+    sqlite3_free(zErr);
+    return;
+  }
+  assert( pVfs );
+  flags |= SQLITE_OPEN_MAIN_DB;
+  rc = sqlite3BtreeOpen(pVfs, zPath, db, &aNew->pBt, 0, flags);
+  sqlite3_free( zPath );
+  db->nDb++;
+  if( rc==SQLITE_CONSTRAINT ){
+    rc = SQLITE_ERROR;
+    zErrDyn = sqlite3MPrintf(db, "database is already attached");
+  }else if( rc==SQLITE_OK ){
+    Pager *pPager;
+    aNew->pSchema = sqlite3SchemaGet(db, aNew->pBt);
+    if( !aNew->pSchema ){
+      rc = SQLITE_NOMEM_BKPT;
+    }else if( aNew->pSchema->file_format && aNew->pSchema->enc!=ENC(db) ){
+      zErrDyn = sqlite3MPrintf(db, 
+        "attached databases must use the same text encoding as main database");
+      rc = SQLITE_ERROR;
+    }
+    sqlite3BtreeEnter(aNew->pBt);
+    pPager = sqlite3BtreePager(aNew->pBt);
+    sqlite3PagerLockingMode(pPager, db->dfltLockMode);
+    sqlite3BtreeSecureDelete(aNew->pBt,
+                             sqlite3BtreeSecureDelete(db->aDb[0].pBt,-1) );
+#ifndef SQLITE_OMIT_PAGER_PRAGMAS
+    sqlite3BtreeSetPagerFlags(aNew->pBt,
+                      PAGER_SYNCHRONOUS_FULL | (db->flags & PAGER_FLAGS_MASK));
+#endif
+    sqlite3BtreeLeave(aNew->pBt);
+  }
+  aNew->safety_level = SQLITE_DEFAULT_SYNCHRONOUS+1;
+  aNew->zDbSName = sqlite3DbStrDup(db, zName);
+  if( rc==SQLITE_OK && aNew->zDbSName==0 ){
+    rc = SQLITE_NOMEM_BKPT;
+  }
+
+
+#ifdef SQLITE_HAS_CODEC
+  if( rc==SQLITE_OK ){
+    extern int sqlite3CodecAttach(sqlite3*, int, const void*, int);
+    extern void sqlite3CodecGetKey(sqlite3*, int, void**, int*);
+    int nKey;
+    char *zKey;
+    int t = sqlite3_value_type(argv[2]);
+    switch( t ){
+      case SQLITE_INTEGER:
+      case SQLITE_FLOAT:
+        zErrDyn = sqlite3DbStrDup(db, "Invalid key value");
+        rc = SQLITE_ERROR;
+        break;
+        
+      case SQLITE_TEXT:
+      case SQLITE_BLOB:
+        nKey = sqlite3_value_bytes(argv[2]);
+        zKey = (char *)sqlite3_value_blob(argv[2]);
+        rc = sqlite3CodecAttach(db, db->nDb-1, zKey, nKey);
+        break;
+
+      case SQLITE_NULL:
+        /* No key specified.  Use the key from the main database */
+        sqlite3CodecGetKey(db, 0, (void**)&zKey, &nKey);
+        if( nKey || sqlite3BtreeGetOptimalReserve(db->aDb[0].pBt)>0 ){
+          rc = sqlite3CodecAttach(db, db->nDb-1, zKey, nKey);
+        }
+        break;
+    }
+  }
+#endif
+
+  /* If the file was opened successfully, read the schema for the new database.
+  ** If this fails, or if opening the file failed, then close the file and 
+  ** remove the entry from the db->aDb[] array. i.e. put everything back the way
+  ** we found it.
+  */
+  if( rc==SQLITE_OK ){
+    sqlite3BtreeEnterAll(db);
+    rc = sqlite3Init(db, &zErrDyn);
+    sqlite3BtreeLeaveAll(db);
+  }
+#ifdef SQLITE_USER_AUTHENTICATION
+  if( rc==SQLITE_OK ){
+    u8 newAuth = 0;
+    rc = sqlite3UserAuthCheckLogin(db, zName, &newAuth);
+    if( newAuth<db->auth.authLevel ){
+      rc = SQLITE_AUTH_USER;
+    }
+  }
+#endif
+  if( rc ){
+    int iDb = db->nDb - 1;
+    assert( iDb>=2 );
+    if( db->aDb[iDb].pBt ){
+      sqlite3BtreeClose(db->aDb[iDb].pBt);
+      db->aDb[iDb].pBt = 0;
+      db->aDb[iDb].pSchema = 0;
+    }
+    sqlite3ResetAllSchemasOfConnection(db);
+    db->nDb = iDb;
+    if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
+      sqlite3OomFault(db);
+      sqlite3DbFree(db, zErrDyn);
+      zErrDyn = sqlite3MPrintf(db, "out of memory");
+    }else if( zErrDyn==0 ){
+      zErrDyn = sqlite3MPrintf(db, "unable to open database: %s", zFile);
+    }
+    goto attach_error;
+  }
+  
+  return;
+
+attach_error:
+  /* Return an error if we get here */
+  if( zErrDyn ){
+    sqlite3_result_error(context, zErrDyn, -1);
+    sqlite3DbFree(db, zErrDyn);
+  }
+  if( rc ) sqlite3_result_error_code(context, rc);
+}
+
+/*
+** An SQL user-function registered to do the work of an DETACH statement. The
+** three arguments to the function come directly from a detach statement:
+**
+**     DETACH DATABASE x
+**
+**     SELECT sqlite_detach(x)
+*/
+static void detachFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **argv
+){
+  const char *zName = (const char *)sqlite3_value_text(argv[0]);
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  int i;
+  Db *pDb = 0;
+  char zErr[128];
+
+  UNUSED_PARAMETER(NotUsed);
+
+  if( zName==0 ) zName = "";
+  for(i=0; i<db->nDb; i++){
+    pDb = &db->aDb[i];
+    if( pDb->pBt==0 ) continue;
+    if( sqlite3StrICmp(pDb->zDbSName, zName)==0 ) break;
+  }
+
+  if( i>=db->nDb ){
+    sqlite3_snprintf(sizeof(zErr),zErr, "no such database: %s", zName);
+    goto detach_error;
+  }
+  if( i<2 ){
+    sqlite3_snprintf(sizeof(zErr),zErr, "cannot detach database %s", zName);
+    goto detach_error;
+  }
+  if( !db->autoCommit ){
+    sqlite3_snprintf(sizeof(zErr), zErr,
+                     "cannot DETACH database within transaction");
+    goto detach_error;
+  }
+  if( sqlite3BtreeIsInReadTrans(pDb->pBt) || sqlite3BtreeIsInBackup(pDb->pBt) ){
+    sqlite3_snprintf(sizeof(zErr),zErr, "database %s is locked", zName);
+    goto detach_error;
+  }
+
+  sqlite3BtreeClose(pDb->pBt);
+  pDb->pBt = 0;
+  pDb->pSchema = 0;
+  sqlite3CollapseDatabaseArray(db);
+  return;
+
+detach_error:
+  sqlite3_result_error(context, zErr, -1);
+}
+
+/*
+** This procedure generates VDBE code for a single invocation of either the
+** sqlite_detach() or sqlite_attach() SQL user functions.
+*/
+static void codeAttach(
+  Parse *pParse,       /* The parser context */
+  int type,            /* Either SQLITE_ATTACH or SQLITE_DETACH */
+  FuncDef const *pFunc,/* FuncDef wrapper for detachFunc() or attachFunc() */
+  Expr *pAuthArg,      /* Expression to pass to authorization callback */
+  Expr *pFilename,     /* Name of database file */
+  Expr *pDbname,       /* Name of the database to use internally */
+  Expr *pKey           /* Database key for encryption extension */
+){
+  int rc;
+  NameContext sName;
+  Vdbe *v;
+  sqlite3* db = pParse->db;
+  int regArgs;
+
+  if( pParse->nErr ) goto attach_end;
+  memset(&sName, 0, sizeof(NameContext));
+  sName.pParse = pParse;
+
+  if( 
+      SQLITE_OK!=(rc = resolveAttachExpr(&sName, pFilename)) ||
+      SQLITE_OK!=(rc = resolveAttachExpr(&sName, pDbname)) ||
+      SQLITE_OK!=(rc = resolveAttachExpr(&sName, pKey))
+  ){
+    goto attach_end;
+  }
+
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  if( pAuthArg ){
+    char *zAuthArg;
+    if( pAuthArg->op==TK_STRING ){
+      zAuthArg = pAuthArg->u.zToken;
+    }else{
+      zAuthArg = 0;
+    }
+    rc = sqlite3AuthCheck(pParse, type, zAuthArg, 0, 0);
+    if(rc!=SQLITE_OK ){
+      goto attach_end;
+    }
+  }
+#endif /* SQLITE_OMIT_AUTHORIZATION */
+
+
+  v = sqlite3GetVdbe(pParse);
+  regArgs = sqlite3GetTempRange(pParse, 4);
+  sqlite3ExprCode(pParse, pFilename, regArgs);
+  sqlite3ExprCode(pParse, pDbname, regArgs+1);
+  sqlite3ExprCode(pParse, pKey, regArgs+2);
+
+  assert( v || db->mallocFailed );
+  if( v ){
+    sqlite3VdbeAddOp4(v, OP_Function0, 0, regArgs+3-pFunc->nArg, regArgs+3,
+                      (char *)pFunc, P4_FUNCDEF);
+    assert( pFunc->nArg==-1 || (pFunc->nArg&0xff)==pFunc->nArg );
+    sqlite3VdbeChangeP5(v, (u8)(pFunc->nArg));
+ 
+    /* Code an OP_Expire. For an ATTACH statement, set P1 to true (expire this
+    ** statement only). For DETACH, set it to false (expire all existing
+    ** statements).
+    */
+    sqlite3VdbeAddOp1(v, OP_Expire, (type==SQLITE_ATTACH));
+  }
+  
+attach_end:
+  sqlite3ExprDelete(db, pFilename);
+  sqlite3ExprDelete(db, pDbname);
+  sqlite3ExprDelete(db, pKey);
+}
+
+/*
+** Called by the parser to compile a DETACH statement.
+**
+**     DETACH pDbname
+*/
+SQLITE_PRIVATE void sqlite3Detach(Parse *pParse, Expr *pDbname){
+  static const FuncDef detach_func = {
+    1,                /* nArg */
+    SQLITE_UTF8,      /* funcFlags */
+    0,                /* pUserData */
+    0,                /* pNext */
+    detachFunc,       /* xSFunc */
+    0,                /* xFinalize */
+    "sqlite_detach",  /* zName */
+    {0}
+  };
+  codeAttach(pParse, SQLITE_DETACH, &detach_func, pDbname, 0, 0, pDbname);
+}
+
+/*
+** Called by the parser to compile an ATTACH statement.
+**
+**     ATTACH p AS pDbname KEY pKey
+*/
+SQLITE_PRIVATE void sqlite3Attach(Parse *pParse, Expr *p, Expr *pDbname, Expr *pKey){
+  static const FuncDef attach_func = {
+    3,                /* nArg */
+    SQLITE_UTF8,      /* funcFlags */
+    0,                /* pUserData */
+    0,                /* pNext */
+    attachFunc,       /* xSFunc */
+    0,                /* xFinalize */
+    "sqlite_attach",  /* zName */
+    {0}
+  };
+  codeAttach(pParse, SQLITE_ATTACH, &attach_func, p, p, pDbname, pKey);
+}
+#endif /* SQLITE_OMIT_ATTACH */
+
+/*
+** Initialize a DbFixer structure.  This routine must be called prior
+** to passing the structure to one of the sqliteFixAAAA() routines below.
+*/
+SQLITE_PRIVATE void sqlite3FixInit(
+  DbFixer *pFix,      /* The fixer to be initialized */
+  Parse *pParse,      /* Error messages will be written here */
+  int iDb,            /* This is the database that must be used */
+  const char *zType,  /* "view", "trigger", or "index" */
+  const Token *pName  /* Name of the view, trigger, or index */
+){
+  sqlite3 *db;
+
+  db = pParse->db;
+  assert( db->nDb>iDb );
+  pFix->pParse = pParse;
+  pFix->zDb = db->aDb[iDb].zDbSName;
+  pFix->pSchema = db->aDb[iDb].pSchema;
+  pFix->zType = zType;
+  pFix->pName = pName;
+  pFix->bVarOnly = (iDb==1);
+}
+
+/*
+** The following set of routines walk through the parse tree and assign
+** a specific database to all table references where the database name
+** was left unspecified in the original SQL statement.  The pFix structure
+** must have been initialized by a prior call to sqlite3FixInit().
+**
+** These routines are used to make sure that an index, trigger, or
+** view in one database does not refer to objects in a different database.
+** (Exception: indices, triggers, and views in the TEMP database are
+** allowed to refer to anything.)  If a reference is explicitly made
+** to an object in a different database, an error message is added to
+** pParse->zErrMsg and these routines return non-zero.  If everything
+** checks out, these routines return 0.
+*/
+SQLITE_PRIVATE int sqlite3FixSrcList(
+  DbFixer *pFix,       /* Context of the fixation */
+  SrcList *pList       /* The Source list to check and modify */
+){
+  int i;
+  const char *zDb;
+  struct SrcList_item *pItem;
+
+  if( NEVER(pList==0) ) return 0;
+  zDb = pFix->zDb;
+  for(i=0, pItem=pList->a; i<pList->nSrc; i++, pItem++){
+    if( pFix->bVarOnly==0 ){
+      if( pItem->zDatabase && sqlite3StrICmp(pItem->zDatabase, zDb) ){
+        sqlite3ErrorMsg(pFix->pParse,
+            "%s %T cannot reference objects in database %s",
+            pFix->zType, pFix->pName, pItem->zDatabase);
+        return 1;
+      }
+      sqlite3DbFree(pFix->pParse->db, pItem->zDatabase);
+      pItem->zDatabase = 0;
+      pItem->pSchema = pFix->pSchema;
+    }
+#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_TRIGGER)
+    if( sqlite3FixSelect(pFix, pItem->pSelect) ) return 1;
+    if( sqlite3FixExpr(pFix, pItem->pOn) ) return 1;
+#endif
+  }
+  return 0;
+}
+#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_TRIGGER)
+SQLITE_PRIVATE int sqlite3FixSelect(
+  DbFixer *pFix,       /* Context of the fixation */
+  Select *pSelect      /* The SELECT statement to be fixed to one database */
+){
+  while( pSelect ){
+    if( sqlite3FixExprList(pFix, pSelect->pEList) ){
+      return 1;
+    }
+    if( sqlite3FixSrcList(pFix, pSelect->pSrc) ){
+      return 1;
+    }
+    if( sqlite3FixExpr(pFix, pSelect->pWhere) ){
+      return 1;
+    }
+    if( sqlite3FixExprList(pFix, pSelect->pGroupBy) ){
+      return 1;
+    }
+    if( sqlite3FixExpr(pFix, pSelect->pHaving) ){
+      return 1;
+    }
+    if( sqlite3FixExprList(pFix, pSelect->pOrderBy) ){
+      return 1;
+    }
+    if( sqlite3FixExpr(pFix, pSelect->pLimit) ){
+      return 1;
+    }
+    if( sqlite3FixExpr(pFix, pSelect->pOffset) ){
+      return 1;
+    }
+    pSelect = pSelect->pPrior;
+  }
+  return 0;
+}
+SQLITE_PRIVATE int sqlite3FixExpr(
+  DbFixer *pFix,     /* Context of the fixation */
+  Expr *pExpr        /* The expression to be fixed to one database */
+){
+  while( pExpr ){
+    if( pExpr->op==TK_VARIABLE ){
+      if( pFix->pParse->db->init.busy ){
+        pExpr->op = TK_NULL;
+      }else{
+        sqlite3ErrorMsg(pFix->pParse, "%s cannot use variables", pFix->zType);
+        return 1;
+      }
+    }
+    if( ExprHasProperty(pExpr, EP_TokenOnly|EP_Leaf) ) break;
+    if( ExprHasProperty(pExpr, EP_xIsSelect) ){
+      if( sqlite3FixSelect(pFix, pExpr->x.pSelect) ) return 1;
+    }else{
+      if( sqlite3FixExprList(pFix, pExpr->x.pList) ) return 1;
+    }
+    if( sqlite3FixExpr(pFix, pExpr->pRight) ){
+      return 1;
+    }
+    pExpr = pExpr->pLeft;
+  }
+  return 0;
+}
+SQLITE_PRIVATE int sqlite3FixExprList(
+  DbFixer *pFix,     /* Context of the fixation */
+  ExprList *pList    /* The expression to be fixed to one database */
+){
+  int i;
+  struct ExprList_item *pItem;
+  if( pList==0 ) return 0;
+  for(i=0, pItem=pList->a; i<pList->nExpr; i++, pItem++){
+    if( sqlite3FixExpr(pFix, pItem->pExpr) ){
+      return 1;
+    }
+  }
+  return 0;
+}
+#endif
+
+#ifndef SQLITE_OMIT_TRIGGER
+SQLITE_PRIVATE int sqlite3FixTriggerStep(
+  DbFixer *pFix,     /* Context of the fixation */
+  TriggerStep *pStep /* The trigger step be fixed to one database */
+){
+  while( pStep ){
+    if( sqlite3FixSelect(pFix, pStep->pSelect) ){
+      return 1;
+    }
+    if( sqlite3FixExpr(pFix, pStep->pWhere) ){
+      return 1;
+    }
+    if( sqlite3FixExprList(pFix, pStep->pExprList) ){
+      return 1;
+    }
+    pStep = pStep->pNext;
+  }
+  return 0;
+}
+#endif
+
+/************** End of attach.c **********************************************/
+/************** Begin file auth.c ********************************************/
+/*
+** 2003 January 11
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains code used to implement the sqlite3_set_authorizer()
+** API.  This facility is an optional feature of the library.  Embedded
+** systems that do not need this facility may omit it by recompiling
+** the library with -DSQLITE_OMIT_AUTHORIZATION=1
+*/
+/* #include "sqliteInt.h" */
+
+/*
+** All of the code in this file may be omitted by defining a single
+** macro.
+*/
+#ifndef SQLITE_OMIT_AUTHORIZATION
+
+/*
+** Set or clear the access authorization function.
+**
+** The access authorization function is be called during the compilation
+** phase to verify that the user has read and/or write access permission on
+** various fields of the database.  The first argument to the auth function
+** is a copy of the 3rd argument to this routine.  The second argument
+** to the auth function is one of these constants:
+**
+**       SQLITE_CREATE_INDEX
+**       SQLITE_CREATE_TABLE
+**       SQLITE_CREATE_TEMP_INDEX
+**       SQLITE_CREATE_TEMP_TABLE
+**       SQLITE_CREATE_TEMP_TRIGGER
+**       SQLITE_CREATE_TEMP_VIEW
+**       SQLITE_CREATE_TRIGGER
+**       SQLITE_CREATE_VIEW
+**       SQLITE_DELETE
+**       SQLITE_DROP_INDEX
+**       SQLITE_DROP_TABLE
+**       SQLITE_DROP_TEMP_INDEX
+**       SQLITE_DROP_TEMP_TABLE
+**       SQLITE_DROP_TEMP_TRIGGER
+**       SQLITE_DROP_TEMP_VIEW
+**       SQLITE_DROP_TRIGGER
+**       SQLITE_DROP_VIEW
+**       SQLITE_INSERT
+**       SQLITE_PRAGMA
+**       SQLITE_READ
+**       SQLITE_SELECT
+**       SQLITE_TRANSACTION
+**       SQLITE_UPDATE
+**
+** The third and fourth arguments to the auth function are the name of
+** the table and the column that are being accessed.  The auth function
+** should return either SQLITE_OK, SQLITE_DENY, or SQLITE_IGNORE.  If
+** SQLITE_OK is returned, it means that access is allowed.  SQLITE_DENY
+** means that the SQL statement will never-run - the sqlite3_exec() call
+** will return with an error.  SQLITE_IGNORE means that the SQL statement
+** should run but attempts to read the specified column will return NULL
+** and attempts to write the column will be ignored.
+**
+** Setting the auth function to NULL disables this hook.  The default
+** setting of the auth function is NULL.
+*/
+SQLITE_API int sqlite3_set_authorizer(
+  sqlite3 *db,
+  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
+  void *pArg
+){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  db->xAuth = (sqlite3_xauth)xAuth;
+  db->pAuthArg = pArg;
+  sqlite3ExpirePreparedStatements(db);
+  sqlite3_mutex_leave(db->mutex);
+  return SQLITE_OK;
+}
+
+/*
+** Write an error message into pParse->zErrMsg that explains that the
+** user-supplied authorization function returned an illegal value.
+*/
+static void sqliteAuthBadReturnCode(Parse *pParse){
+  sqlite3ErrorMsg(pParse, "authorizer malfunction");
+  pParse->rc = SQLITE_ERROR;
+}
+
+/*
+** Invoke the authorization callback for permission to read column zCol from
+** table zTab in database zDb. This function assumes that an authorization
+** callback has been registered (i.e. that sqlite3.xAuth is not NULL).
+**
+** If SQLITE_IGNORE is returned and pExpr is not NULL, then pExpr is changed
+** to an SQL NULL expression. Otherwise, if pExpr is NULL, then SQLITE_IGNORE
+** is treated as SQLITE_DENY. In this case an error is left in pParse.
+*/
+SQLITE_PRIVATE int sqlite3AuthReadCol(
+  Parse *pParse,                  /* The parser context */
+  const char *zTab,               /* Table name */
+  const char *zCol,               /* Column name */
+  int iDb                         /* Index of containing database. */
+){
+  sqlite3 *db = pParse->db;          /* Database handle */
+  char *zDb = db->aDb[iDb].zDbSName; /* Schema name of attached database */
+  int rc;                            /* Auth callback return code */
+
+  if( db->init.busy ) return SQLITE_OK;
+  rc = db->xAuth(db->pAuthArg, SQLITE_READ, zTab,zCol,zDb,pParse->zAuthContext
+#ifdef SQLITE_USER_AUTHENTICATION
+                 ,db->auth.zAuthUser
+#endif
+                );
+  if( rc==SQLITE_DENY ){
+    if( db->nDb>2 || iDb!=0 ){
+      sqlite3ErrorMsg(pParse, "access to %s.%s.%s is prohibited",zDb,zTab,zCol);
+    }else{
+      sqlite3ErrorMsg(pParse, "access to %s.%s is prohibited", zTab, zCol);
+    }
+    pParse->rc = SQLITE_AUTH;
+  }else if( rc!=SQLITE_IGNORE && rc!=SQLITE_OK ){
+    sqliteAuthBadReturnCode(pParse);
+  }
+  return rc;
+}
+
+/*
+** The pExpr should be a TK_COLUMN expression.  The table referred to
+** is in pTabList or else it is the NEW or OLD table of a trigger.  
+** Check to see if it is OK to read this particular column.
+**
+** If the auth function returns SQLITE_IGNORE, change the TK_COLUMN 
+** instruction into a TK_NULL.  If the auth function returns SQLITE_DENY,
+** then generate an error.
+*/
+SQLITE_PRIVATE void sqlite3AuthRead(
+  Parse *pParse,        /* The parser context */
+  Expr *pExpr,          /* The expression to check authorization on */
+  Schema *pSchema,      /* The schema of the expression */
+  SrcList *pTabList     /* All table that pExpr might refer to */
+){
+  sqlite3 *db = pParse->db;
+  Table *pTab = 0;      /* The table being read */
+  const char *zCol;     /* Name of the column of the table */
+  int iSrc;             /* Index in pTabList->a[] of table being read */
+  int iDb;              /* The index of the database the expression refers to */
+  int iCol;             /* Index of column in table */
+
+  if( db->xAuth==0 ) return;
+  iDb = sqlite3SchemaToIndex(pParse->db, pSchema);
+  if( iDb<0 ){
+    /* An attempt to read a column out of a subquery or other
+    ** temporary table. */
+    return;
+  }
+
+  assert( pExpr->op==TK_COLUMN || pExpr->op==TK_TRIGGER );
+  if( pExpr->op==TK_TRIGGER ){
+    pTab = pParse->pTriggerTab;
+  }else{
+    assert( pTabList );
+    for(iSrc=0; ALWAYS(iSrc<pTabList->nSrc); iSrc++){
+      if( pExpr->iTable==pTabList->a[iSrc].iCursor ){
+        pTab = pTabList->a[iSrc].pTab;
+        break;
+      }
+    }
+  }
+  iCol = pExpr->iColumn;
+  if( NEVER(pTab==0) ) return;
+
+  if( iCol>=0 ){
+    assert( iCol<pTab->nCol );
+    zCol = pTab->aCol[iCol].zName;
+  }else if( pTab->iPKey>=0 ){
+    assert( pTab->iPKey<pTab->nCol );
+    zCol = pTab->aCol[pTab->iPKey].zName;
+  }else{
+    zCol = "ROWID";
+  }
+  assert( iDb>=0 && iDb<db->nDb );
+  if( SQLITE_IGNORE==sqlite3AuthReadCol(pParse, pTab->zName, zCol, iDb) ){
+    pExpr->op = TK_NULL;
+  }
+}
+
+/*
+** Do an authorization check using the code and arguments given.  Return
+** either SQLITE_OK (zero) or SQLITE_IGNORE or SQLITE_DENY.  If SQLITE_DENY
+** is returned, then the error count and error message in pParse are
+** modified appropriately.
+*/
+SQLITE_PRIVATE int sqlite3AuthCheck(
+  Parse *pParse,
+  int code,
+  const char *zArg1,
+  const char *zArg2,
+  const char *zArg3
+){
+  sqlite3 *db = pParse->db;
+  int rc;
+
+  /* Don't do any authorization checks if the database is initialising
+  ** or if the parser is being invoked from within sqlite3_declare_vtab.
+  */
+  if( db->init.busy || IN_DECLARE_VTAB ){
+    return SQLITE_OK;
+  }
+
+  if( db->xAuth==0 ){
+    return SQLITE_OK;
+  }
+  rc = db->xAuth(db->pAuthArg, code, zArg1, zArg2, zArg3, pParse->zAuthContext
+#ifdef SQLITE_USER_AUTHENTICATION
+                 ,db->auth.zAuthUser
+#endif
+                );
+  if( rc==SQLITE_DENY ){
+    sqlite3ErrorMsg(pParse, "not authorized");
+    pParse->rc = SQLITE_AUTH;
+  }else if( rc!=SQLITE_OK && rc!=SQLITE_IGNORE ){
+    rc = SQLITE_DENY;
+    sqliteAuthBadReturnCode(pParse);
+  }
+  return rc;
+}
+
+/*
+** Push an authorization context.  After this routine is called, the
+** zArg3 argument to authorization callbacks will be zContext until
+** popped.  Or if pParse==0, this routine is a no-op.
+*/
+SQLITE_PRIVATE void sqlite3AuthContextPush(
+  Parse *pParse,
+  AuthContext *pContext, 
+  const char *zContext
+){
+  assert( pParse );
+  pContext->pParse = pParse;
+  pContext->zAuthContext = pParse->zAuthContext;
+  pParse->zAuthContext = zContext;
+}
+
+/*
+** Pop an authorization context that was previously pushed
+** by sqlite3AuthContextPush
+*/
+SQLITE_PRIVATE void sqlite3AuthContextPop(AuthContext *pContext){
+  if( pContext->pParse ){
+    pContext->pParse->zAuthContext = pContext->zAuthContext;
+    pContext->pParse = 0;
+  }
+}
+
+#endif /* SQLITE_OMIT_AUTHORIZATION */
+
+/************** End of auth.c ************************************************/
+/************** Begin file build.c *******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains C code routines that are called by the SQLite parser
+** when syntax rules are reduced.  The routines in this file handle the
+** following kinds of SQL syntax:
+**
+**     CREATE TABLE
+**     DROP TABLE
+**     CREATE INDEX
+**     DROP INDEX
+**     creating ID lists
+**     BEGIN TRANSACTION
+**     COMMIT
+**     ROLLBACK
+*/
+/* #include "sqliteInt.h" */
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+/*
+** The TableLock structure is only used by the sqlite3TableLock() and
+** codeTableLocks() functions.
+*/
+struct TableLock {
+  int iDb;             /* The database containing the table to be locked */
+  int iTab;            /* The root page of the table to be locked */
+  u8 isWriteLock;      /* True for write lock.  False for a read lock */
+  const char *zName;   /* Name of the table */
+};
+
+/*
+** Record the fact that we want to lock a table at run-time.  
+**
+** The table to be locked has root page iTab and is found in database iDb.
+** A read or a write lock can be taken depending on isWritelock.
+**
+** This routine just records the fact that the lock is desired.  The
+** code to make the lock occur is generated by a later call to
+** codeTableLocks() which occurs during sqlite3FinishCoding().
+*/
+SQLITE_PRIVATE void sqlite3TableLock(
+  Parse *pParse,     /* Parsing context */
+  int iDb,           /* Index of the database containing the table to lock */
+  int iTab,          /* Root page number of the table to be locked */
+  u8 isWriteLock,    /* True for a write lock */
+  const char *zName  /* Name of the table to be locked */
+){
+  Parse *pToplevel = sqlite3ParseToplevel(pParse);
+  int i;
+  int nBytes;
+  TableLock *p;
+  assert( iDb>=0 );
+
+  for(i=0; i<pToplevel->nTableLock; i++){
+    p = &pToplevel->aTableLock[i];
+    if( p->iDb==iDb && p->iTab==iTab ){
+      p->isWriteLock = (p->isWriteLock || isWriteLock);
+      return;
+    }
+  }
+
+  nBytes = sizeof(TableLock) * (pToplevel->nTableLock+1);
+  pToplevel->aTableLock =
+      sqlite3DbReallocOrFree(pToplevel->db, pToplevel->aTableLock, nBytes);
+  if( pToplevel->aTableLock ){
+    p = &pToplevel->aTableLock[pToplevel->nTableLock++];
+    p->iDb = iDb;
+    p->iTab = iTab;
+    p->isWriteLock = isWriteLock;
+    p->zName = zName;
+  }else{
+    pToplevel->nTableLock = 0;
+    sqlite3OomFault(pToplevel->db);
+  }
+}
+
+/*
+** Code an OP_TableLock instruction for each table locked by the
+** statement (configured by calls to sqlite3TableLock()).
+*/
+static void codeTableLocks(Parse *pParse){
+  int i;
+  Vdbe *pVdbe; 
+
+  pVdbe = sqlite3GetVdbe(pParse);
+  assert( pVdbe!=0 ); /* sqlite3GetVdbe cannot fail: VDBE already allocated */
+
+  for(i=0; i<pParse->nTableLock; i++){
+    TableLock *p = &pParse->aTableLock[i];
+    int p1 = p->iDb;
+    sqlite3VdbeAddOp4(pVdbe, OP_TableLock, p1, p->iTab, p->isWriteLock,
+                      p->zName, P4_STATIC);
+  }
+}
+#else
+  #define codeTableLocks(x)
+#endif
+
+/*
+** Return TRUE if the given yDbMask object is empty - if it contains no
+** 1 bits.  This routine is used by the DbMaskAllZero() and DbMaskNotZero()
+** macros when SQLITE_MAX_ATTACHED is greater than 30.
+*/
+#if SQLITE_MAX_ATTACHED>30
+SQLITE_PRIVATE int sqlite3DbMaskAllZero(yDbMask m){
+  int i;
+  for(i=0; i<sizeof(yDbMask); i++) if( m[i] ) return 0;
+  return 1;
+}
+#endif
+
+/*
+** This routine is called after a single SQL statement has been
+** parsed and a VDBE program to execute that statement has been
+** prepared.  This routine puts the finishing touches on the
+** VDBE program and resets the pParse structure for the next
+** parse.
+**
+** Note that if an error occurred, it might be the case that
+** no VDBE code was generated.
+*/
+SQLITE_PRIVATE void sqlite3FinishCoding(Parse *pParse){
+  sqlite3 *db;
+  Vdbe *v;
+
+  assert( pParse->pToplevel==0 );
+  db = pParse->db;
+  if( pParse->nested ) return;
+  if( db->mallocFailed || pParse->nErr ){
+    if( pParse->rc==SQLITE_OK ) pParse->rc = SQLITE_ERROR;
+    return;
+  }
+
+  /* Begin by generating some termination code at the end of the
+  ** vdbe program
+  */
+  v = sqlite3GetVdbe(pParse);
+  assert( !pParse->isMultiWrite 
+       || sqlite3VdbeAssertMayAbort(v, pParse->mayAbort));
+  if( v ){
+    sqlite3VdbeAddOp0(v, OP_Halt);
+
+#if SQLITE_USER_AUTHENTICATION
+    if( pParse->nTableLock>0 && db->init.busy==0 ){
+      sqlite3UserAuthInit(db);
+      if( db->auth.authLevel<UAUTH_User ){
+        sqlite3ErrorMsg(pParse, "user not authenticated");
+        pParse->rc = SQLITE_AUTH_USER;
+        return;
+      }
+    }
+#endif
+
+    /* The cookie mask contains one bit for each database file open.
+    ** (Bit 0 is for main, bit 1 is for temp, and so forth.)  Bits are
+    ** set for each database that is used.  Generate code to start a
+    ** transaction on each used database and to verify the schema cookie
+    ** on each used database.
+    */
+    if( db->mallocFailed==0 
+     && (DbMaskNonZero(pParse->cookieMask) || pParse->pConstExpr)
+    ){
+      int iDb, i;
+      assert( sqlite3VdbeGetOp(v, 0)->opcode==OP_Init );
+      sqlite3VdbeJumpHere(v, 0);
+      for(iDb=0; iDb<db->nDb; iDb++){
+        Schema *pSchema;
+        if( DbMaskTest(pParse->cookieMask, iDb)==0 ) continue;
+        sqlite3VdbeUsesBtree(v, iDb);
+        pSchema = db->aDb[iDb].pSchema;
+        sqlite3VdbeAddOp4Int(v,
+          OP_Transaction,                    /* Opcode */
+          iDb,                               /* P1 */
+          DbMaskTest(pParse->writeMask,iDb), /* P2 */
+          pSchema->schema_cookie,            /* P3 */
+          pSchema->iGeneration               /* P4 */
+        );
+        if( db->init.busy==0 ) sqlite3VdbeChangeP5(v, 1);
+        VdbeComment((v,
+              "usesStmtJournal=%d", pParse->mayAbort && pParse->isMultiWrite));
+      }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+      for(i=0; i<pParse->nVtabLock; i++){
+        char *vtab = (char *)sqlite3GetVTable(db, pParse->apVtabLock[i]);
+        sqlite3VdbeAddOp4(v, OP_VBegin, 0, 0, 0, vtab, P4_VTAB);
+      }
+      pParse->nVtabLock = 0;
+#endif
+
+      /* Once all the cookies have been verified and transactions opened, 
+      ** obtain the required table-locks. This is a no-op unless the 
+      ** shared-cache feature is enabled.
+      */
+      codeTableLocks(pParse);
+
+      /* Initialize any AUTOINCREMENT data structures required.
+      */
+      sqlite3AutoincrementBegin(pParse);
+
+      /* Code constant expressions that where factored out of inner loops */
+      if( pParse->pConstExpr ){
+        ExprList *pEL = pParse->pConstExpr;
+        pParse->okConstFactor = 0;
+        for(i=0; i<pEL->nExpr; i++){
+          sqlite3ExprCode(pParse, pEL->a[i].pExpr, pEL->a[i].u.iConstExprReg);
+        }
+      }
+
+      /* Finally, jump back to the beginning of the executable code. */
+      sqlite3VdbeGoto(v, 1);
+    }
+  }
+
+
+  /* Get the VDBE program ready for execution
+  */
+  if( v && pParse->nErr==0 && !db->mallocFailed ){
+    assert( pParse->iCacheLevel==0 );  /* Disables and re-enables match */
+    /* A minimum of one cursor is required if autoincrement is used
+    *  See ticket [a696379c1f08866] */
+    if( pParse->pAinc!=0 && pParse->nTab==0 ) pParse->nTab = 1;
+    sqlite3VdbeMakeReady(v, pParse);
+    pParse->rc = SQLITE_DONE;
+  }else{
+    pParse->rc = SQLITE_ERROR;
+  }
+}
+
+/*
+** Run the parser and code generator recursively in order to generate
+** code for the SQL statement given onto the end of the pParse context
+** currently under construction.  When the parser is run recursively
+** this way, the final OP_Halt is not appended and other initialization
+** and finalization steps are omitted because those are handling by the
+** outermost parser.
+**
+** Not everything is nestable.  This facility is designed to permit
+** INSERT, UPDATE, and DELETE operations against SQLITE_MASTER.  Use
+** care if you decide to try to use this routine for some other purposes.
+*/
+SQLITE_PRIVATE void sqlite3NestedParse(Parse *pParse, const char *zFormat, ...){
+  va_list ap;
+  char *zSql;
+  char *zErrMsg = 0;
+  sqlite3 *db = pParse->db;
+  char saveBuf[PARSE_TAIL_SZ];
+
+  if( pParse->nErr ) return;
+  assert( pParse->nested<10 );  /* Nesting should only be of limited depth */
+  va_start(ap, zFormat);
+  zSql = sqlite3VMPrintf(db, zFormat, ap);
+  va_end(ap);
+  if( zSql==0 ){
+    return;   /* A malloc must have failed */
+  }
+  pParse->nested++;
+  memcpy(saveBuf, PARSE_TAIL(pParse), PARSE_TAIL_SZ);
+  memset(PARSE_TAIL(pParse), 0, PARSE_TAIL_SZ);
+  sqlite3RunParser(pParse, zSql, &zErrMsg);
+  sqlite3DbFree(db, zErrMsg);
+  sqlite3DbFree(db, zSql);
+  memcpy(PARSE_TAIL(pParse), saveBuf, PARSE_TAIL_SZ);
+  pParse->nested--;
+}
+
+#if SQLITE_USER_AUTHENTICATION
+/*
+** Return TRUE if zTable is the name of the system table that stores the
+** list of users and their access credentials.
+*/
+SQLITE_PRIVATE int sqlite3UserAuthTable(const char *zTable){
+  return sqlite3_stricmp(zTable, "sqlite_user")==0;
+}
+#endif
+
+/*
+** Locate the in-memory structure that describes a particular database
+** table given the name of that table and (optionally) the name of the
+** database containing the table.  Return NULL if not found.
+**
+** If zDatabase is 0, all databases are searched for the table and the
+** first matching table is returned.  (No checking for duplicate table
+** names is done.)  The search order is TEMP first, then MAIN, then any
+** auxiliary databases added using the ATTACH command.
+**
+** See also sqlite3LocateTable().
+*/
+SQLITE_PRIVATE Table *sqlite3FindTable(sqlite3 *db, const char *zName, const char *zDatabase){
+  Table *p = 0;
+  int i;
+
+  /* All mutexes are required for schema access.  Make sure we hold them. */
+  assert( zDatabase!=0 || sqlite3BtreeHoldsAllMutexes(db) );
+#if SQLITE_USER_AUTHENTICATION
+  /* Only the admin user is allowed to know that the sqlite_user table
+  ** exists */
+  if( db->auth.authLevel<UAUTH_Admin && sqlite3UserAuthTable(zName)!=0 ){
+    return 0;
+  }
+#endif
+  for(i=OMIT_TEMPDB; i<db->nDb; i++){
+    int j = (i<2) ? i^1 : i;   /* Search TEMP before MAIN */
+    if( zDatabase==0 || sqlite3StrICmp(zDatabase, db->aDb[j].zDbSName)==0 ){
+      assert( sqlite3SchemaMutexHeld(db, j, 0) );
+      p = sqlite3HashFind(&db->aDb[j].pSchema->tblHash, zName);
+      if( p ) break;
+    }
+  }
+  return p;
+}
+
+/*
+** Locate the in-memory structure that describes a particular database
+** table given the name of that table and (optionally) the name of the
+** database containing the table.  Return NULL if not found.  Also leave an
+** error message in pParse->zErrMsg.
+**
+** The difference between this routine and sqlite3FindTable() is that this
+** routine leaves an error message in pParse->zErrMsg where
+** sqlite3FindTable() does not.
+*/
+SQLITE_PRIVATE Table *sqlite3LocateTable(
+  Parse *pParse,         /* context in which to report errors */
+  u32 flags,             /* LOCATE_VIEW or LOCATE_NOERR */
+  const char *zName,     /* Name of the table we are looking for */
+  const char *zDbase     /* Name of the database.  Might be NULL */
+){
+  Table *p;
+
+  /* Read the database schema. If an error occurs, leave an error message
+  ** and code in pParse and return NULL. */
+  if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
+    return 0;
+  }
+
+  p = sqlite3FindTable(pParse->db, zName, zDbase);
+  if( p==0 ){
+    const char *zMsg = flags & LOCATE_VIEW ? "no such view" : "no such table";
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    if( sqlite3FindDbName(pParse->db, zDbase)<1 ){
+      /* If zName is the not the name of a table in the schema created using
+      ** CREATE, then check to see if it is the name of an virtual table that
+      ** can be an eponymous virtual table. */
+      Module *pMod = (Module*)sqlite3HashFind(&pParse->db->aModule, zName);
+      if( pMod && sqlite3VtabEponymousTableInit(pParse, pMod) ){
+        return pMod->pEpoTab;
+      }
+    }
+#endif
+    if( (flags & LOCATE_NOERR)==0 ){
+      if( zDbase ){
+        sqlite3ErrorMsg(pParse, "%s: %s.%s", zMsg, zDbase, zName);
+      }else{
+        sqlite3ErrorMsg(pParse, "%s: %s", zMsg, zName);
+      }
+      pParse->checkSchema = 1;
+    }
+  }
+
+  return p;
+}
+
+/*
+** Locate the table identified by *p.
+**
+** This is a wrapper around sqlite3LocateTable(). The difference between
+** sqlite3LocateTable() and this function is that this function restricts
+** the search to schema (p->pSchema) if it is not NULL. p->pSchema may be
+** non-NULL if it is part of a view or trigger program definition. See
+** sqlite3FixSrcList() for details.
+*/
+SQLITE_PRIVATE Table *sqlite3LocateTableItem(
+  Parse *pParse, 
+  u32 flags,
+  struct SrcList_item *p
+){
+  const char *zDb;
+  assert( p->pSchema==0 || p->zDatabase==0 );
+  if( p->pSchema ){
+    int iDb = sqlite3SchemaToIndex(pParse->db, p->pSchema);
+    zDb = pParse->db->aDb[iDb].zDbSName;
+  }else{
+    zDb = p->zDatabase;
+  }
+  return sqlite3LocateTable(pParse, flags, p->zName, zDb);
+}
+
+/*
+** Locate the in-memory structure that describes 
+** a particular index given the name of that index
+** and the name of the database that contains the index.
+** Return NULL if not found.
+**
+** If zDatabase is 0, all databases are searched for the
+** table and the first matching index is returned.  (No checking
+** for duplicate index names is done.)  The search order is
+** TEMP first, then MAIN, then any auxiliary databases added
+** using the ATTACH command.
+*/
+SQLITE_PRIVATE Index *sqlite3FindIndex(sqlite3 *db, const char *zName, const char *zDb){
+  Index *p = 0;
+  int i;
+  /* All mutexes are required for schema access.  Make sure we hold them. */
+  assert( zDb!=0 || sqlite3BtreeHoldsAllMutexes(db) );
+  for(i=OMIT_TEMPDB; i<db->nDb; i++){
+    int j = (i<2) ? i^1 : i;  /* Search TEMP before MAIN */
+    Schema *pSchema = db->aDb[j].pSchema;
+    assert( pSchema );
+    if( zDb && sqlite3StrICmp(zDb, db->aDb[j].zDbSName) ) continue;
+    assert( sqlite3SchemaMutexHeld(db, j, 0) );
+    p = sqlite3HashFind(&pSchema->idxHash, zName);
+    if( p ) break;
+  }
+  return p;
+}
+
+/*
+** Reclaim the memory used by an index
+*/
+static void freeIndex(sqlite3 *db, Index *p){
+#ifndef SQLITE_OMIT_ANALYZE
+  sqlite3DeleteIndexSamples(db, p);
+#endif
+  sqlite3ExprDelete(db, p->pPartIdxWhere);
+  sqlite3ExprListDelete(db, p->aColExpr);
+  sqlite3DbFree(db, p->zColAff);
+  if( p->isResized ) sqlite3DbFree(db, (void *)p->azColl);
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  sqlite3_free(p->aiRowEst);
+#endif
+  sqlite3DbFree(db, p);
+}
+
+/*
+** For the index called zIdxName which is found in the database iDb,
+** unlike that index from its Table then remove the index from
+** the index hash table and free all memory structures associated
+** with the index.
+*/
+SQLITE_PRIVATE void sqlite3UnlinkAndDeleteIndex(sqlite3 *db, int iDb, const char *zIdxName){
+  Index *pIndex;
+  Hash *pHash;
+
+  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+  pHash = &db->aDb[iDb].pSchema->idxHash;
+  pIndex = sqlite3HashInsert(pHash, zIdxName, 0);
+  if( ALWAYS(pIndex) ){
+    if( pIndex->pTable->pIndex==pIndex ){
+      pIndex->pTable->pIndex = pIndex->pNext;
+    }else{
+      Index *p;
+      /* Justification of ALWAYS();  The index must be on the list of
+      ** indices. */
+      p = pIndex->pTable->pIndex;
+      while( ALWAYS(p) && p->pNext!=pIndex ){ p = p->pNext; }
+      if( ALWAYS(p && p->pNext==pIndex) ){
+        p->pNext = pIndex->pNext;
+      }
+    }
+    freeIndex(db, pIndex);
+  }
+  db->flags |= SQLITE_InternChanges;
+}
+
+/*
+** Look through the list of open database files in db->aDb[] and if
+** any have been closed, remove them from the list.  Reallocate the
+** db->aDb[] structure to a smaller size, if possible.
+**
+** Entry 0 (the "main" database) and entry 1 (the "temp" database)
+** are never candidates for being collapsed.
+*/
+SQLITE_PRIVATE void sqlite3CollapseDatabaseArray(sqlite3 *db){
+  int i, j;
+  for(i=j=2; i<db->nDb; i++){
+    struct Db *pDb = &db->aDb[i];
+    if( pDb->pBt==0 ){
+      sqlite3DbFree(db, pDb->zDbSName);
+      pDb->zDbSName = 0;
+      continue;
+    }
+    if( j<i ){
+      db->aDb[j] = db->aDb[i];
+    }
+    j++;
+  }
+  db->nDb = j;
+  if( db->nDb<=2 && db->aDb!=db->aDbStatic ){
+    memcpy(db->aDbStatic, db->aDb, 2*sizeof(db->aDb[0]));
+    sqlite3DbFree(db, db->aDb);
+    db->aDb = db->aDbStatic;
+  }
+}
+
+/*
+** Reset the schema for the database at index iDb.  Also reset the
+** TEMP schema.
+*/
+SQLITE_PRIVATE void sqlite3ResetOneSchema(sqlite3 *db, int iDb){
+  Db *pDb;
+  assert( iDb<db->nDb );
+
+  /* Case 1:  Reset the single schema identified by iDb */
+  pDb = &db->aDb[iDb];
+  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+  assert( pDb->pSchema!=0 );
+  sqlite3SchemaClear(pDb->pSchema);
+
+  /* If any database other than TEMP is reset, then also reset TEMP
+  ** since TEMP might be holding triggers that reference tables in the
+  ** other database.
+  */
+  if( iDb!=1 ){
+    pDb = &db->aDb[1];
+    assert( pDb->pSchema!=0 );
+    sqlite3SchemaClear(pDb->pSchema);
+  }
+  return;
+}
+
+/*
+** Erase all schema information from all attached databases (including
+** "main" and "temp") for a single database connection.
+*/
+SQLITE_PRIVATE void sqlite3ResetAllSchemasOfConnection(sqlite3 *db){
+  int i;
+  sqlite3BtreeEnterAll(db);
+  for(i=0; i<db->nDb; i++){
+    Db *pDb = &db->aDb[i];
+    if( pDb->pSchema ){
+      sqlite3SchemaClear(pDb->pSchema);
+    }
+  }
+  db->flags &= ~SQLITE_InternChanges;
+  sqlite3VtabUnlockList(db);
+  sqlite3BtreeLeaveAll(db);
+  sqlite3CollapseDatabaseArray(db);
+}
+
+/*
+** This routine is called when a commit occurs.
+*/
+SQLITE_PRIVATE void sqlite3CommitInternalChanges(sqlite3 *db){
+  db->flags &= ~SQLITE_InternChanges;
+}
+
+/*
+** Delete memory allocated for the column names of a table or view (the
+** Table.aCol[] array).
+*/
+SQLITE_PRIVATE void sqlite3DeleteColumnNames(sqlite3 *db, Table *pTable){
+  int i;
+  Column *pCol;
+  assert( pTable!=0 );
+  if( (pCol = pTable->aCol)!=0 ){
+    for(i=0; i<pTable->nCol; i++, pCol++){
+      sqlite3DbFree(db, pCol->zName);
+      sqlite3ExprDelete(db, pCol->pDflt);
+      sqlite3DbFree(db, pCol->zColl);
+    }
+    sqlite3DbFree(db, pTable->aCol);
+  }
+}
+
+/*
+** Remove the memory data structures associated with the given
+** Table.  No changes are made to disk by this routine.
+**
+** This routine just deletes the data structure.  It does not unlink
+** the table data structure from the hash table.  But it does destroy
+** memory structures of the indices and foreign keys associated with 
+** the table.
+**
+** The db parameter is optional.  It is needed if the Table object 
+** contains lookaside memory.  (Table objects in the schema do not use
+** lookaside memory, but some ephemeral Table objects do.)  Or the
+** db parameter can be used with db->pnBytesFreed to measure the memory
+** used by the Table object.
+*/
+static void SQLITE_NOINLINE deleteTable(sqlite3 *db, Table *pTable){
+  Index *pIndex, *pNext;
+  TESTONLY( int nLookaside; ) /* Used to verify lookaside not used for schema */
+
+  /* Record the number of outstanding lookaside allocations in schema Tables
+  ** prior to doing any free() operations.  Since schema Tables do not use
+  ** lookaside, this number should not change. */
+  TESTONLY( nLookaside = (db && (pTable->tabFlags & TF_Ephemeral)==0) ?
+                         db->lookaside.nOut : 0 );
+
+  /* Delete all indices associated with this table. */
+  for(pIndex = pTable->pIndex; pIndex; pIndex=pNext){
+    pNext = pIndex->pNext;
+    assert( pIndex->pSchema==pTable->pSchema
+         || (IsVirtual(pTable) && pIndex->idxType!=SQLITE_IDXTYPE_APPDEF) );
+    if( (db==0 || db->pnBytesFreed==0) && !IsVirtual(pTable) ){
+      char *zName = pIndex->zName; 
+      TESTONLY ( Index *pOld = ) sqlite3HashInsert(
+         &pIndex->pSchema->idxHash, zName, 0
+      );
+      assert( db==0 || sqlite3SchemaMutexHeld(db, 0, pIndex->pSchema) );
+      assert( pOld==pIndex || pOld==0 );
+    }
+    freeIndex(db, pIndex);
+  }
+
+  /* Delete any foreign keys attached to this table. */
+  sqlite3FkDelete(db, pTable);
+
+  /* Delete the Table structure itself.
+  */
+  sqlite3DeleteColumnNames(db, pTable);
+  sqlite3DbFree(db, pTable->zName);
+  sqlite3DbFree(db, pTable->zColAff);
+  sqlite3SelectDelete(db, pTable->pSelect);
+  sqlite3ExprListDelete(db, pTable->pCheck);
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  sqlite3VtabClear(db, pTable);
+#endif
+  sqlite3DbFree(db, pTable);
+
+  /* Verify that no lookaside memory was used by schema tables */
+  assert( nLookaside==0 || nLookaside==db->lookaside.nOut );
+}
+SQLITE_PRIVATE void sqlite3DeleteTable(sqlite3 *db, Table *pTable){
+  /* Do not delete the table until the reference count reaches zero. */
+  if( !pTable ) return;
+  if( ((!db || db->pnBytesFreed==0) && (--pTable->nRef)>0) ) return;
+  deleteTable(db, pTable);
+}
+
+
+/*
+** Unlink the given table from the hash tables and the delete the
+** table structure with all its indices and foreign keys.
+*/
+SQLITE_PRIVATE void sqlite3UnlinkAndDeleteTable(sqlite3 *db, int iDb, const char *zTabName){
+  Table *p;
+  Db *pDb;
+
+  assert( db!=0 );
+  assert( iDb>=0 && iDb<db->nDb );
+  assert( zTabName );
+  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+  testcase( zTabName[0]==0 );  /* Zero-length table names are allowed */
+  pDb = &db->aDb[iDb];
+  p = sqlite3HashInsert(&pDb->pSchema->tblHash, zTabName, 0);
+  sqlite3DeleteTable(db, p);
+  db->flags |= SQLITE_InternChanges;
+}
+
+/*
+** Given a token, return a string that consists of the text of that
+** token.  Space to hold the returned string
+** is obtained from sqliteMalloc() and must be freed by the calling
+** function.
+**
+** Any quotation marks (ex:  "name", 'name', [name], or `name`) that
+** surround the body of the token are removed.
+**
+** Tokens are often just pointers into the original SQL text and so
+** are not \000 terminated and are not persistent.  The returned string
+** is \000 terminated and is persistent.
+*/
+SQLITE_PRIVATE char *sqlite3NameFromToken(sqlite3 *db, Token *pName){
+  char *zName;
+  if( pName ){
+    zName = sqlite3DbStrNDup(db, (char*)pName->z, pName->n);
+    sqlite3Dequote(zName);
+  }else{
+    zName = 0;
+  }
+  return zName;
+}
+
+/*
+** Open the sqlite_master table stored in database number iDb for
+** writing. The table is opened using cursor 0.
+*/
+SQLITE_PRIVATE void sqlite3OpenMasterTable(Parse *p, int iDb){
+  Vdbe *v = sqlite3GetVdbe(p);
+  sqlite3TableLock(p, iDb, MASTER_ROOT, 1, SCHEMA_TABLE(iDb));
+  sqlite3VdbeAddOp4Int(v, OP_OpenWrite, 0, MASTER_ROOT, iDb, 5);
+  if( p->nTab==0 ){
+    p->nTab = 1;
+  }
+}
+
+/*
+** Parameter zName points to a nul-terminated buffer containing the name
+** of a database ("main", "temp" or the name of an attached db). This
+** function returns the index of the named database in db->aDb[], or
+** -1 if the named db cannot be found.
+*/
+SQLITE_PRIVATE int sqlite3FindDbName(sqlite3 *db, const char *zName){
+  int i = -1;         /* Database number */
+  if( zName ){
+    Db *pDb;
+    for(i=(db->nDb-1), pDb=&db->aDb[i]; i>=0; i--, pDb--){
+      if( 0==sqlite3StrICmp(pDb->zDbSName, zName) ) break;
+    }
+  }
+  return i;
+}
+
+/*
+** The token *pName contains the name of a database (either "main" or
+** "temp" or the name of an attached db). This routine returns the
+** index of the named database in db->aDb[], or -1 if the named db 
+** does not exist.
+*/
+SQLITE_PRIVATE int sqlite3FindDb(sqlite3 *db, Token *pName){
+  int i;                               /* Database number */
+  char *zName;                         /* Name we are searching for */
+  zName = sqlite3NameFromToken(db, pName);
+  i = sqlite3FindDbName(db, zName);
+  sqlite3DbFree(db, zName);
+  return i;
+}
+
+/* The table or view or trigger name is passed to this routine via tokens
+** pName1 and pName2. If the table name was fully qualified, for example:
+**
+** CREATE TABLE xxx.yyy (...);
+** 
+** Then pName1 is set to "xxx" and pName2 "yyy". On the other hand if
+** the table name is not fully qualified, i.e.:
+**
+** CREATE TABLE yyy(...);
+**
+** Then pName1 is set to "yyy" and pName2 is "".
+**
+** This routine sets the *ppUnqual pointer to point at the token (pName1 or
+** pName2) that stores the unqualified table name.  The index of the
+** database "xxx" is returned.
+*/
+SQLITE_PRIVATE int sqlite3TwoPartName(
+  Parse *pParse,      /* Parsing and code generating context */
+  Token *pName1,      /* The "xxx" in the name "xxx.yyy" or "xxx" */
+  Token *pName2,      /* The "yyy" in the name "xxx.yyy" */
+  Token **pUnqual     /* Write the unqualified object name here */
+){
+  int iDb;                    /* Database holding the object */
+  sqlite3 *db = pParse->db;
+
+  assert( pName2!=0 );
+  if( pName2->n>0 ){
+    if( db->init.busy ) {
+      sqlite3ErrorMsg(pParse, "corrupt database");
+      return -1;
+    }
+    *pUnqual = pName2;
+    iDb = sqlite3FindDb(db, pName1);
+    if( iDb<0 ){
+      sqlite3ErrorMsg(pParse, "unknown database %T", pName1);
+      return -1;
+    }
+  }else{
+    assert( db->init.iDb==0 || db->init.busy || (db->flags & SQLITE_Vacuum)!=0);
+    iDb = db->init.iDb;
+    *pUnqual = pName1;
+  }
+  return iDb;
+}
+
+/*
+** This routine is used to check if the UTF-8 string zName is a legal
+** unqualified name for a new schema object (table, index, view or
+** trigger). All names are legal except those that begin with the string
+** "sqlite_" (in upper, lower or mixed case). This portion of the namespace
+** is reserved for internal use.
+*/
+SQLITE_PRIVATE int sqlite3CheckObjectName(Parse *pParse, const char *zName){
+  if( !pParse->db->init.busy && pParse->nested==0 
+          && (pParse->db->flags & SQLITE_WriteSchema)==0
+          && 0==sqlite3StrNICmp(zName, "sqlite_", 7) ){
+    sqlite3ErrorMsg(pParse, "object name reserved for internal use: %s", zName);
+    return SQLITE_ERROR;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Return the PRIMARY KEY index of a table
+*/
+SQLITE_PRIVATE Index *sqlite3PrimaryKeyIndex(Table *pTab){
+  Index *p;
+  for(p=pTab->pIndex; p && !IsPrimaryKeyIndex(p); p=p->pNext){}
+  return p;
+}
+
+/*
+** Return the column of index pIdx that corresponds to table
+** column iCol.  Return -1 if not found.
+*/
+SQLITE_PRIVATE i16 sqlite3ColumnOfIndex(Index *pIdx, i16 iCol){
+  int i;
+  for(i=0; i<pIdx->nColumn; i++){
+    if( iCol==pIdx->aiColumn[i] ) return i;
+  }
+  return -1;
+}
+
+/*
+** Begin constructing a new table representation in memory.  This is
+** the first of several action routines that get called in response
+** to a CREATE TABLE statement.  In particular, this routine is called
+** after seeing tokens "CREATE" and "TABLE" and the table name. The isTemp
+** flag is true if the table should be stored in the auxiliary database
+** file instead of in the main database file.  This is normally the case
+** when the "TEMP" or "TEMPORARY" keyword occurs in between
+** CREATE and TABLE.
+**
+** The new table record is initialized and put in pParse->pNewTable.
+** As more of the CREATE TABLE statement is parsed, additional action
+** routines will be called to add more information to this record.
+** At the end of the CREATE TABLE statement, the sqlite3EndTable() routine
+** is called to complete the construction of the new table record.
+*/
+SQLITE_PRIVATE void sqlite3StartTable(
+  Parse *pParse,   /* Parser context */
+  Token *pName1,   /* First part of the name of the table or view */
+  Token *pName2,   /* Second part of the name of the table or view */
+  int isTemp,      /* True if this is a TEMP table */
+  int isView,      /* True if this is a VIEW */
+  int isVirtual,   /* True if this is a VIRTUAL table */
+  int noErr        /* Do nothing if table already exists */
+){
+  Table *pTable;
+  char *zName = 0; /* The name of the new table */
+  sqlite3 *db = pParse->db;
+  Vdbe *v;
+  int iDb;         /* Database number to create the table in */
+  Token *pName;    /* Unqualified name of the table to create */
+
+  if( db->init.busy && db->init.newTnum==1 ){
+    /* Special case:  Parsing the sqlite_master or sqlite_temp_master schema */
+    iDb = db->init.iDb;
+    zName = sqlite3DbStrDup(db, SCHEMA_TABLE(iDb));
+    pName = pName1;
+  }else{
+    /* The common case */
+    iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pName);
+    if( iDb<0 ) return;
+    if( !OMIT_TEMPDB && isTemp && pName2->n>0 && iDb!=1 ){
+      /* If creating a temp table, the name may not be qualified. Unless 
+      ** the database name is "temp" anyway.  */
+      sqlite3ErrorMsg(pParse, "temporary table name must be unqualified");
+      return;
+    }
+    if( !OMIT_TEMPDB && isTemp ) iDb = 1;
+    zName = sqlite3NameFromToken(db, pName);
+  }
+  pParse->sNameToken = *pName;
+  if( zName==0 ) return;
+  if( SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){
+    goto begin_table_error;
+  }
+  if( db->init.iDb==1 ) isTemp = 1;
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  assert( isTemp==0 || isTemp==1 );
+  assert( isView==0 || isView==1 );
+  {
+    static const u8 aCode[] = {
+       SQLITE_CREATE_TABLE,
+       SQLITE_CREATE_TEMP_TABLE,
+       SQLITE_CREATE_VIEW,
+       SQLITE_CREATE_TEMP_VIEW
+    };
+    char *zDb = db->aDb[iDb].zDbSName;
+    if( sqlite3AuthCheck(pParse, SQLITE_INSERT, SCHEMA_TABLE(isTemp), 0, zDb) ){
+      goto begin_table_error;
+    }
+    if( !isVirtual && sqlite3AuthCheck(pParse, (int)aCode[isTemp+2*isView],
+                                       zName, 0, zDb) ){
+      goto begin_table_error;
+    }
+  }
+#endif
+
+  /* Make sure the new table name does not collide with an existing
+  ** index or table name in the same database.  Issue an error message if
+  ** it does. The exception is if the statement being parsed was passed
+  ** to an sqlite3_declare_vtab() call. In that case only the column names
+  ** and types will be used, so there is no need to test for namespace
+  ** collisions.
+  */
+  if( !IN_DECLARE_VTAB ){
+    char *zDb = db->aDb[iDb].zDbSName;
+    if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
+      goto begin_table_error;
+    }
+    pTable = sqlite3FindTable(db, zName, zDb);
+    if( pTable ){
+      if( !noErr ){
+        sqlite3ErrorMsg(pParse, "table %T already exists", pName);
+      }else{
+        assert( !db->init.busy || CORRUPT_DB );
+        sqlite3CodeVerifySchema(pParse, iDb);
+      }
+      goto begin_table_error;
+    }
+    if( sqlite3FindIndex(db, zName, zDb)!=0 ){
+      sqlite3ErrorMsg(pParse, "there is already an index named %s", zName);
+      goto begin_table_error;
+    }
+  }
+
+  pTable = sqlite3DbMallocZero(db, sizeof(Table));
+  if( pTable==0 ){
+    assert( db->mallocFailed );
+    pParse->rc = SQLITE_NOMEM_BKPT;
+    pParse->nErr++;
+    goto begin_table_error;
+  }
+  pTable->zName = zName;
+  pTable->iPKey = -1;
+  pTable->pSchema = db->aDb[iDb].pSchema;
+  pTable->nRef = 1;
+  pTable->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) );
+  assert( pParse->pNewTable==0 );
+  pParse->pNewTable = pTable;
+
+  /* If this is the magic sqlite_sequence table used by autoincrement,
+  ** then record a pointer to this table in the main database structure
+  ** so that INSERT can find the table easily.
+  */
+#ifndef SQLITE_OMIT_AUTOINCREMENT
+  if( !pParse->nested && strcmp(zName, "sqlite_sequence")==0 ){
+    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+    pTable->pSchema->pSeqTab = pTable;
+  }
+#endif
+
+  /* Begin generating the code that will insert the table record into
+  ** the SQLITE_MASTER table.  Note in particular that we must go ahead
+  ** and allocate the record number for the table entry now.  Before any
+  ** PRIMARY KEY or UNIQUE keywords are parsed.  Those keywords will cause
+  ** indices to be created and the table record must come before the 
+  ** indices.  Hence, the record number for the table must be allocated
+  ** now.
+  */
+  if( !db->init.busy && (v = sqlite3GetVdbe(pParse))!=0 ){
+    int addr1;
+    int fileFormat;
+    int reg1, reg2, reg3;
+    /* nullRow[] is an OP_Record encoding of a row containing 5 NULLs */
+    static const char nullRow[] = { 6, 0, 0, 0, 0, 0 };
+    sqlite3BeginWriteOperation(pParse, 1, iDb);
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    if( isVirtual ){
+      sqlite3VdbeAddOp0(v, OP_VBegin);
+    }
+#endif
+
+    /* If the file format and encoding in the database have not been set, 
+    ** set them now.
+    */
+    reg1 = pParse->regRowid = ++pParse->nMem;
+    reg2 = pParse->regRoot = ++pParse->nMem;
+    reg3 = ++pParse->nMem;
+    sqlite3VdbeAddOp3(v, OP_ReadCookie, iDb, reg3, BTREE_FILE_FORMAT);
+    sqlite3VdbeUsesBtree(v, iDb);
+    addr1 = sqlite3VdbeAddOp1(v, OP_If, reg3); VdbeCoverage(v);
+    fileFormat = (db->flags & SQLITE_LegacyFileFmt)!=0 ?
+                  1 : SQLITE_MAX_FILE_FORMAT;
+    sqlite3VdbeAddOp3(v, OP_SetCookie, iDb, BTREE_FILE_FORMAT, fileFormat);
+    sqlite3VdbeAddOp3(v, OP_SetCookie, iDb, BTREE_TEXT_ENCODING, ENC(db));
+    sqlite3VdbeJumpHere(v, addr1);
+
+    /* This just creates a place-holder record in the sqlite_master table.
+    ** The record created does not contain anything yet.  It will be replaced
+    ** by the real entry in code generated at sqlite3EndTable().
+    **
+    ** The rowid for the new entry is left in register pParse->regRowid.
+    ** The root page number of the new table is left in reg pParse->regRoot.
+    ** The rowid and root page number values are needed by the code that
+    ** sqlite3EndTable will generate.
+    */
+#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_VIRTUALTABLE)
+    if( isView || isVirtual ){
+      sqlite3VdbeAddOp2(v, OP_Integer, 0, reg2);
+    }else
+#endif
+    {
+      pParse->addrCrTab = sqlite3VdbeAddOp2(v, OP_CreateTable, iDb, reg2);
+    }
+    sqlite3OpenMasterTable(pParse, iDb);
+    sqlite3VdbeAddOp2(v, OP_NewRowid, 0, reg1);
+    sqlite3VdbeAddOp4(v, OP_Blob, 6, reg3, 0, nullRow, P4_STATIC);
+    sqlite3VdbeAddOp3(v, OP_Insert, 0, reg3, reg1);
+    sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
+    sqlite3VdbeAddOp0(v, OP_Close);
+  }
+
+  /* Normal (non-error) return. */
+  return;
+
+  /* If an error occurs, we jump here */
+begin_table_error:
+  sqlite3DbFree(db, zName);
+  return;
+}
+
+/* Set properties of a table column based on the (magical)
+** name of the column.
+*/
+#if SQLITE_ENABLE_HIDDEN_COLUMNS
+SQLITE_PRIVATE void sqlite3ColumnPropertiesFromName(Table *pTab, Column *pCol){
+  if( sqlite3_strnicmp(pCol->zName, "__hidden__", 10)==0 ){
+    pCol->colFlags |= COLFLAG_HIDDEN;
+  }else if( pTab && pCol!=pTab->aCol && (pCol[-1].colFlags & COLFLAG_HIDDEN) ){
+    pTab->tabFlags |= TF_OOOHidden;
+  }
+}
+#endif
+
+
+/*
+** Add a new column to the table currently being constructed.
+**
+** The parser calls this routine once for each column declaration
+** in a CREATE TABLE statement.  sqlite3StartTable() gets called
+** first to get things going.  Then this routine is called for each
+** column.
+*/
+SQLITE_PRIVATE void sqlite3AddColumn(Parse *pParse, Token *pName, Token *pType){
+  Table *p;
+  int i;
+  char *z;
+  char *zType;
+  Column *pCol;
+  sqlite3 *db = pParse->db;
+  if( (p = pParse->pNewTable)==0 ) return;
+#if SQLITE_MAX_COLUMN
+  if( p->nCol+1>db->aLimit[SQLITE_LIMIT_COLUMN] ){
+    sqlite3ErrorMsg(pParse, "too many columns on %s", p->zName);
+    return;
+  }
+#endif
+  z = sqlite3DbMallocRaw(db, pName->n + pType->n + 2);
+  if( z==0 ) return;
+  memcpy(z, pName->z, pName->n);
+  z[pName->n] = 0;
+  sqlite3Dequote(z);
+  for(i=0; i<p->nCol; i++){
+    if( sqlite3_stricmp(z, p->aCol[i].zName)==0 ){
+      sqlite3ErrorMsg(pParse, "duplicate column name: %s", z);
+      sqlite3DbFree(db, z);
+      return;
+    }
+  }
+  if( (p->nCol & 0x7)==0 ){
+    Column *aNew;
+    aNew = sqlite3DbRealloc(db,p->aCol,(p->nCol+8)*sizeof(p->aCol[0]));
+    if( aNew==0 ){
+      sqlite3DbFree(db, z);
+      return;
+    }
+    p->aCol = aNew;
+  }
+  pCol = &p->aCol[p->nCol];
+  memset(pCol, 0, sizeof(p->aCol[0]));
+  pCol->zName = z;
+  sqlite3ColumnPropertiesFromName(p, pCol);
+ 
+  if( pType->n==0 ){
+    /* If there is no type specified, columns have the default affinity
+    ** 'BLOB'. */
+    pCol->affinity = SQLITE_AFF_BLOB;
+    pCol->szEst = 1;
+  }else{
+    zType = z + sqlite3Strlen30(z) + 1;
+    memcpy(zType, pType->z, pType->n);
+    zType[pType->n] = 0;
+    sqlite3Dequote(zType);
+    pCol->affinity = sqlite3AffinityType(zType, &pCol->szEst);
+    pCol->colFlags |= COLFLAG_HASTYPE;
+  }
+  p->nCol++;
+  pParse->constraintName.n = 0;
+}
+
+/*
+** This routine is called by the parser while in the middle of
+** parsing a CREATE TABLE statement.  A "NOT NULL" constraint has
+** been seen on a column.  This routine sets the notNull flag on
+** the column currently under construction.
+*/
+SQLITE_PRIVATE void sqlite3AddNotNull(Parse *pParse, int onError){
+  Table *p;
+  p = pParse->pNewTable;
+  if( p==0 || NEVER(p->nCol<1) ) return;
+  p->aCol[p->nCol-1].notNull = (u8)onError;
+}
+
+/*
+** Scan the column type name zType (length nType) and return the
+** associated affinity type.
+**
+** This routine does a case-independent search of zType for the 
+** substrings in the following table. If one of the substrings is
+** found, the corresponding affinity is returned. If zType contains
+** more than one of the substrings, entries toward the top of 
+** the table take priority. For example, if zType is 'BLOBINT', 
+** SQLITE_AFF_INTEGER is returned.
+**
+** Substring     | Affinity
+** --------------------------------
+** 'INT'         | SQLITE_AFF_INTEGER
+** 'CHAR'        | SQLITE_AFF_TEXT
+** 'CLOB'        | SQLITE_AFF_TEXT
+** 'TEXT'        | SQLITE_AFF_TEXT
+** 'BLOB'        | SQLITE_AFF_BLOB
+** 'REAL'        | SQLITE_AFF_REAL
+** 'FLOA'        | SQLITE_AFF_REAL
+** 'DOUB'        | SQLITE_AFF_REAL
+**
+** If none of the substrings in the above table are found,
+** SQLITE_AFF_NUMERIC is returned.
+*/
+SQLITE_PRIVATE char sqlite3AffinityType(const char *zIn, u8 *pszEst){
+  u32 h = 0;
+  char aff = SQLITE_AFF_NUMERIC;
+  const char *zChar = 0;
+
+  assert( zIn!=0 );
+  while( zIn[0] ){
+    h = (h<<8) + sqlite3UpperToLower[(*zIn)&0xff];
+    zIn++;
+    if( h==(('c'<<24)+('h'<<16)+('a'<<8)+'r') ){             /* CHAR */
+      aff = SQLITE_AFF_TEXT;
+      zChar = zIn;
+    }else if( h==(('c'<<24)+('l'<<16)+('o'<<8)+'b') ){       /* CLOB */
+      aff = SQLITE_AFF_TEXT;
+    }else if( h==(('t'<<24)+('e'<<16)+('x'<<8)+'t') ){       /* TEXT */
+      aff = SQLITE_AFF_TEXT;
+    }else if( h==(('b'<<24)+('l'<<16)+('o'<<8)+'b')          /* BLOB */
+        && (aff==SQLITE_AFF_NUMERIC || aff==SQLITE_AFF_REAL) ){
+      aff = SQLITE_AFF_BLOB;
+      if( zIn[0]=='(' ) zChar = zIn;
+#ifndef SQLITE_OMIT_FLOATING_POINT
+    }else if( h==(('r'<<24)+('e'<<16)+('a'<<8)+'l')          /* REAL */
+        && aff==SQLITE_AFF_NUMERIC ){
+      aff = SQLITE_AFF_REAL;
+    }else if( h==(('f'<<24)+('l'<<16)+('o'<<8)+'a')          /* FLOA */
+        && aff==SQLITE_AFF_NUMERIC ){
+      aff = SQLITE_AFF_REAL;
+    }else if( h==(('d'<<24)+('o'<<16)+('u'<<8)+'b')          /* DOUB */
+        && aff==SQLITE_AFF_NUMERIC ){
+      aff = SQLITE_AFF_REAL;
+#endif
+    }else if( (h&0x00FFFFFF)==(('i'<<16)+('n'<<8)+'t') ){    /* INT */
+      aff = SQLITE_AFF_INTEGER;
+      break;
+    }
+  }
+
+  /* If pszEst is not NULL, store an estimate of the field size.  The
+  ** estimate is scaled so that the size of an integer is 1.  */
+  if( pszEst ){
+    *pszEst = 1;   /* default size is approx 4 bytes */
+    if( aff<SQLITE_AFF_NUMERIC ){
+      if( zChar ){
+        while( zChar[0] ){
+          if( sqlite3Isdigit(zChar[0]) ){
+            int v = 0;
+            sqlite3GetInt32(zChar, &v);
+            v = v/4 + 1;
+            if( v>255 ) v = 255;
+            *pszEst = v; /* BLOB(k), VARCHAR(k), CHAR(k) -> r=(k/4+1) */
+            break;
+          }
+          zChar++;
+        }
+      }else{
+        *pszEst = 5;   /* BLOB, TEXT, CLOB -> r=5  (approx 20 bytes)*/
+      }
+    }
+  }
+  return aff;
+}
+
+/*
+** The expression is the default value for the most recently added column
+** of the table currently under construction.
+**
+** Default value expressions must be constant.  Raise an exception if this
+** is not the case.
+**
+** This routine is called by the parser while in the middle of
+** parsing a CREATE TABLE statement.
+*/
+SQLITE_PRIVATE void sqlite3AddDefaultValue(Parse *pParse, ExprSpan *pSpan){
+  Table *p;
+  Column *pCol;
+  sqlite3 *db = pParse->db;
+  p = pParse->pNewTable;
+  if( p!=0 ){
+    pCol = &(p->aCol[p->nCol-1]);
+    if( !sqlite3ExprIsConstantOrFunction(pSpan->pExpr, db->init.busy) ){
+      sqlite3ErrorMsg(pParse, "default value of column [%s] is not constant",
+          pCol->zName);
+    }else{
+      /* A copy of pExpr is used instead of the original, as pExpr contains
+      ** tokens that point to volatile memory. The 'span' of the expression
+      ** is required by pragma table_info.
+      */
+      Expr x;
+      sqlite3ExprDelete(db, pCol->pDflt);
+      memset(&x, 0, sizeof(x));
+      x.op = TK_SPAN;
+      x.u.zToken = sqlite3DbStrNDup(db, (char*)pSpan->zStart,
+                                    (int)(pSpan->zEnd - pSpan->zStart));
+      x.pLeft = pSpan->pExpr;
+      x.flags = EP_Skip;
+      pCol->pDflt = sqlite3ExprDup(db, &x, EXPRDUP_REDUCE);
+      sqlite3DbFree(db, x.u.zToken);
+    }
+  }
+  sqlite3ExprDelete(db, pSpan->pExpr);
+}
+
+/*
+** Backwards Compatibility Hack:
+** 
+** Historical versions of SQLite accepted strings as column names in
+** indexes and PRIMARY KEY constraints and in UNIQUE constraints.  Example:
+**
+**     CREATE TABLE xyz(a,b,c,d,e,PRIMARY KEY('a'),UNIQUE('b','c' COLLATE trim)
+**     CREATE INDEX abc ON xyz('c','d' DESC,'e' COLLATE nocase DESC);
+**
+** This is goofy.  But to preserve backwards compatibility we continue to
+** accept it.  This routine does the necessary conversion.  It converts
+** the expression given in its argument from a TK_STRING into a TK_ID
+** if the expression is just a TK_STRING with an optional COLLATE clause.
+** If the epxression is anything other than TK_STRING, the expression is
+** unchanged.
+*/
+static void sqlite3StringToId(Expr *p){
+  if( p->op==TK_STRING ){
+    p->op = TK_ID;
+  }else if( p->op==TK_COLLATE && p->pLeft->op==TK_STRING ){
+    p->pLeft->op = TK_ID;
+  }
+}
+
+/*
+** Designate the PRIMARY KEY for the table.  pList is a list of names 
+** of columns that form the primary key.  If pList is NULL, then the
+** most recently added column of the table is the primary key.
+**
+** A table can have at most one primary key.  If the table already has
+** a primary key (and this is the second primary key) then create an
+** error.
+**
+** If the PRIMARY KEY is on a single column whose datatype is INTEGER,
+** then we will try to use that column as the rowid.  Set the Table.iPKey
+** field of the table under construction to be the index of the
+** INTEGER PRIMARY KEY column.  Table.iPKey is set to -1 if there is
+** no INTEGER PRIMARY KEY.
+**
+** If the key is not an INTEGER PRIMARY KEY, then create a unique
+** index for the key.  No index is created for INTEGER PRIMARY KEYs.
+*/
+SQLITE_PRIVATE void sqlite3AddPrimaryKey(
+  Parse *pParse,    /* Parsing context */
+  ExprList *pList,  /* List of field names to be indexed */
+  int onError,      /* What to do with a uniqueness conflict */
+  int autoInc,      /* True if the AUTOINCREMENT keyword is present */
+  int sortOrder     /* SQLITE_SO_ASC or SQLITE_SO_DESC */
+){
+  Table *pTab = pParse->pNewTable;
+  Column *pCol = 0;
+  int iCol = -1, i;
+  int nTerm;
+  if( pTab==0 ) goto primary_key_exit;
+  if( pTab->tabFlags & TF_HasPrimaryKey ){
+    sqlite3ErrorMsg(pParse, 
+      "table \"%s\" has more than one primary key", pTab->zName);
+    goto primary_key_exit;
+  }
+  pTab->tabFlags |= TF_HasPrimaryKey;
+  if( pList==0 ){
+    iCol = pTab->nCol - 1;
+    pCol = &pTab->aCol[iCol];
+    pCol->colFlags |= COLFLAG_PRIMKEY;
+    nTerm = 1;
+  }else{
+    nTerm = pList->nExpr;
+    for(i=0; i<nTerm; i++){
+      Expr *pCExpr = sqlite3ExprSkipCollate(pList->a[i].pExpr);
+      assert( pCExpr!=0 );
+      sqlite3StringToId(pCExpr);
+      if( pCExpr->op==TK_ID ){
+        const char *zCName = pCExpr->u.zToken;
+        for(iCol=0; iCol<pTab->nCol; iCol++){
+          if( sqlite3StrICmp(zCName, pTab->aCol[iCol].zName)==0 ){
+            pCol = &pTab->aCol[iCol];
+            pCol->colFlags |= COLFLAG_PRIMKEY;
+            break;
+          }
+        }
+      }
+    }
+  }
+  if( nTerm==1
+   && pCol
+   && sqlite3StrICmp(sqlite3ColumnType(pCol,""), "INTEGER")==0
+   && sortOrder!=SQLITE_SO_DESC
+  ){
+    pTab->iPKey = iCol;
+    pTab->keyConf = (u8)onError;
+    assert( autoInc==0 || autoInc==1 );
+    pTab->tabFlags |= autoInc*TF_Autoincrement;
+    if( pList ) pParse->iPkSortOrder = pList->a[0].sortOrder;
+  }else if( autoInc ){
+#ifndef SQLITE_OMIT_AUTOINCREMENT
+    sqlite3ErrorMsg(pParse, "AUTOINCREMENT is only allowed on an "
+       "INTEGER PRIMARY KEY");
+#endif
+  }else{
+    sqlite3CreateIndex(pParse, 0, 0, 0, pList, onError, 0,
+                           0, sortOrder, 0, SQLITE_IDXTYPE_PRIMARYKEY);
+    pList = 0;
+  }
+
+primary_key_exit:
+  sqlite3ExprListDelete(pParse->db, pList);
+  return;
+}
+
+/*
+** Add a new CHECK constraint to the table currently under construction.
+*/
+SQLITE_PRIVATE void sqlite3AddCheckConstraint(
+  Parse *pParse,    /* Parsing context */
+  Expr *pCheckExpr  /* The check expression */
+){
+#ifndef SQLITE_OMIT_CHECK
+  Table *pTab = pParse->pNewTable;
+  sqlite3 *db = pParse->db;
+  if( pTab && !IN_DECLARE_VTAB
+   && !sqlite3BtreeIsReadonly(db->aDb[db->init.iDb].pBt)
+  ){
+    pTab->pCheck = sqlite3ExprListAppend(pParse, pTab->pCheck, pCheckExpr);
+    if( pParse->constraintName.n ){
+      sqlite3ExprListSetName(pParse, pTab->pCheck, &pParse->constraintName, 1);
+    }
+  }else
+#endif
+  {
+    sqlite3ExprDelete(pParse->db, pCheckExpr);
+  }
+}
+
+/*
+** Set the collation function of the most recently parsed table column
+** to the CollSeq given.
+*/
+SQLITE_PRIVATE void sqlite3AddCollateType(Parse *pParse, Token *pToken){
+  Table *p;
+  int i;
+  char *zColl;              /* Dequoted name of collation sequence */
+  sqlite3 *db;
+
+  if( (p = pParse->pNewTable)==0 ) return;
+  i = p->nCol-1;
+  db = pParse->db;
+  zColl = sqlite3NameFromToken(db, pToken);
+  if( !zColl ) return;
+
+  if( sqlite3LocateCollSeq(pParse, zColl) ){
+    Index *pIdx;
+    sqlite3DbFree(db, p->aCol[i].zColl);
+    p->aCol[i].zColl = zColl;
+  
+    /* If the column is declared as "<name> PRIMARY KEY COLLATE <type>",
+    ** then an index may have been created on this column before the
+    ** collation type was added. Correct this if it is the case.
+    */
+    for(pIdx=p->pIndex; pIdx; pIdx=pIdx->pNext){
+      assert( pIdx->nKeyCol==1 );
+      if( pIdx->aiColumn[0]==i ){
+        pIdx->azColl[0] = p->aCol[i].zColl;
+      }
+    }
+  }else{
+    sqlite3DbFree(db, zColl);
+  }
+}
+
+/*
+** This function returns the collation sequence for database native text
+** encoding identified by the string zName, length nName.
+**
+** If the requested collation sequence is not available, or not available
+** in the database native encoding, the collation factory is invoked to
+** request it. If the collation factory does not supply such a sequence,
+** and the sequence is available in another text encoding, then that is
+** returned instead.
+**
+** If no versions of the requested collations sequence are available, or
+** another error occurs, NULL is returned and an error message written into
+** pParse.
+**
+** This routine is a wrapper around sqlite3FindCollSeq().  This routine
+** invokes the collation factory if the named collation cannot be found
+** and generates an error message.
+**
+** See also: sqlite3FindCollSeq(), sqlite3GetCollSeq()
+*/
+SQLITE_PRIVATE CollSeq *sqlite3LocateCollSeq(Parse *pParse, const char *zName){
+  sqlite3 *db = pParse->db;
+  u8 enc = ENC(db);
+  u8 initbusy = db->init.busy;
+  CollSeq *pColl;
+
+  pColl = sqlite3FindCollSeq(db, enc, zName, initbusy);
+  if( !initbusy && (!pColl || !pColl->xCmp) ){
+    pColl = sqlite3GetCollSeq(pParse, enc, pColl, zName);
+  }
+
+  return pColl;
+}
+
+
+/*
+** Generate code that will increment the schema cookie.
+**
+** The schema cookie is used to determine when the schema for the
+** database changes.  After each schema change, the cookie value
+** changes.  When a process first reads the schema it records the
+** cookie.  Thereafter, whenever it goes to access the database,
+** it checks the cookie to make sure the schema has not changed
+** since it was last read.
+**
+** This plan is not completely bullet-proof.  It is possible for
+** the schema to change multiple times and for the cookie to be
+** set back to prior value.  But schema changes are infrequent
+** and the probability of hitting the same cookie value is only
+** 1 chance in 2^32.  So we're safe enough.
+**
+** IMPLEMENTATION-OF: R-34230-56049 SQLite automatically increments
+** the schema-version whenever the schema changes.
+*/
+SQLITE_PRIVATE void sqlite3ChangeCookie(Parse *pParse, int iDb){
+  sqlite3 *db = pParse->db;
+  Vdbe *v = pParse->pVdbe;
+  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+  sqlite3VdbeAddOp3(v, OP_SetCookie, iDb, BTREE_SCHEMA_VERSION, 
+                    db->aDb[iDb].pSchema->schema_cookie+1);
+}
+
+/*
+** Measure the number of characters needed to output the given
+** identifier.  The number returned includes any quotes used
+** but does not include the null terminator.
+**
+** The estimate is conservative.  It might be larger that what is
+** really needed.
+*/
+static int identLength(const char *z){
+  int n;
+  for(n=0; *z; n++, z++){
+    if( *z=='"' ){ n++; }
+  }
+  return n + 2;
+}
+
+/*
+** The first parameter is a pointer to an output buffer. The second 
+** parameter is a pointer to an integer that contains the offset at
+** which to write into the output buffer. This function copies the
+** nul-terminated string pointed to by the third parameter, zSignedIdent,
+** to the specified offset in the buffer and updates *pIdx to refer
+** to the first byte after the last byte written before returning.
+** 
+** If the string zSignedIdent consists entirely of alpha-numeric
+** characters, does not begin with a digit and is not an SQL keyword,
+** then it is copied to the output buffer exactly as it is. Otherwise,
+** it is quoted using double-quotes.
+*/
+static void identPut(char *z, int *pIdx, char *zSignedIdent){
+  unsigned char *zIdent = (unsigned char*)zSignedIdent;
+  int i, j, needQuote;
+  i = *pIdx;
+
+  for(j=0; zIdent[j]; j++){
+    if( !sqlite3Isalnum(zIdent[j]) && zIdent[j]!='_' ) break;
+  }
+  needQuote = sqlite3Isdigit(zIdent[0])
+            || sqlite3KeywordCode(zIdent, j)!=TK_ID
+            || zIdent[j]!=0
+            || j==0;
+
+  if( needQuote ) z[i++] = '"';
+  for(j=0; zIdent[j]; j++){
+    z[i++] = zIdent[j];
+    if( zIdent[j]=='"' ) z[i++] = '"';
+  }
+  if( needQuote ) z[i++] = '"';
+  z[i] = 0;
+  *pIdx = i;
+}
+
+/*
+** Generate a CREATE TABLE statement appropriate for the given
+** table.  Memory to hold the text of the statement is obtained
+** from sqliteMalloc() and must be freed by the calling function.
+*/
+static char *createTableStmt(sqlite3 *db, Table *p){
+  int i, k, n;
+  char *zStmt;
+  char *zSep, *zSep2, *zEnd;
+  Column *pCol;
+  n = 0;
+  for(pCol = p->aCol, i=0; i<p->nCol; i++, pCol++){
+    n += identLength(pCol->zName) + 5;
+  }
+  n += identLength(p->zName);
+  if( n<50 ){ 
+    zSep = "";
+    zSep2 = ",";
+    zEnd = ")";
+  }else{
+    zSep = "\n  ";
+    zSep2 = ",\n  ";
+    zEnd = "\n)";
+  }
+  n += 35 + 6*p->nCol;
+  zStmt = sqlite3DbMallocRaw(0, n);
+  if( zStmt==0 ){
+    sqlite3OomFault(db);
+    return 0;
+  }
+  sqlite3_snprintf(n, zStmt, "CREATE TABLE ");
+  k = sqlite3Strlen30(zStmt);
+  identPut(zStmt, &k, p->zName);
+  zStmt[k++] = '(';
+  for(pCol=p->aCol, i=0; i<p->nCol; i++, pCol++){
+    static const char * const azType[] = {
+        /* SQLITE_AFF_BLOB    */ "",
+        /* SQLITE_AFF_TEXT    */ " TEXT",
+        /* SQLITE_AFF_NUMERIC */ " NUM",
+        /* SQLITE_AFF_INTEGER */ " INT",
+        /* SQLITE_AFF_REAL    */ " REAL"
+    };
+    int len;
+    const char *zType;
+
+    sqlite3_snprintf(n-k, &zStmt[k], zSep);
+    k += sqlite3Strlen30(&zStmt[k]);
+    zSep = zSep2;
+    identPut(zStmt, &k, pCol->zName);
+    assert( pCol->affinity-SQLITE_AFF_BLOB >= 0 );
+    assert( pCol->affinity-SQLITE_AFF_BLOB < ArraySize(azType) );
+    testcase( pCol->affinity==SQLITE_AFF_BLOB );
+    testcase( pCol->affinity==SQLITE_AFF_TEXT );
+    testcase( pCol->affinity==SQLITE_AFF_NUMERIC );
+    testcase( pCol->affinity==SQLITE_AFF_INTEGER );
+    testcase( pCol->affinity==SQLITE_AFF_REAL );
+    
+    zType = azType[pCol->affinity - SQLITE_AFF_BLOB];
+    len = sqlite3Strlen30(zType);
+    assert( pCol->affinity==SQLITE_AFF_BLOB 
+            || pCol->affinity==sqlite3AffinityType(zType, 0) );
+    memcpy(&zStmt[k], zType, len);
+    k += len;
+    assert( k<=n );
+  }
+  sqlite3_snprintf(n-k, &zStmt[k], "%s", zEnd);
+  return zStmt;
+}
+
+/*
+** Resize an Index object to hold N columns total.  Return SQLITE_OK
+** on success and SQLITE_NOMEM on an OOM error.
+*/
+static int resizeIndexObject(sqlite3 *db, Index *pIdx, int N){
+  char *zExtra;
+  int nByte;
+  if( pIdx->nColumn>=N ) return SQLITE_OK;
+  assert( pIdx->isResized==0 );
+  nByte = (sizeof(char*) + sizeof(i16) + 1)*N;
+  zExtra = sqlite3DbMallocZero(db, nByte);
+  if( zExtra==0 ) return SQLITE_NOMEM_BKPT;
+  memcpy(zExtra, pIdx->azColl, sizeof(char*)*pIdx->nColumn);
+  pIdx->azColl = (const char**)zExtra;
+  zExtra += sizeof(char*)*N;
+  memcpy(zExtra, pIdx->aiColumn, sizeof(i16)*pIdx->nColumn);
+  pIdx->aiColumn = (i16*)zExtra;
+  zExtra += sizeof(i16)*N;
+  memcpy(zExtra, pIdx->aSortOrder, pIdx->nColumn);
+  pIdx->aSortOrder = (u8*)zExtra;
+  pIdx->nColumn = N;
+  pIdx->isResized = 1;
+  return SQLITE_OK;
+}
+
+/*
+** Estimate the total row width for a table.
+*/
+static void estimateTableWidth(Table *pTab){
+  unsigned wTable = 0;
+  const Column *pTabCol;
+  int i;
+  for(i=pTab->nCol, pTabCol=pTab->aCol; i>0; i--, pTabCol++){
+    wTable += pTabCol->szEst;
+  }
+  if( pTab->iPKey<0 ) wTable++;
+  pTab->szTabRow = sqlite3LogEst(wTable*4);
+}
+
+/*
+** Estimate the average size of a row for an index.
+*/
+static void estimateIndexWidth(Index *pIdx){
+  unsigned wIndex = 0;
+  int i;
+  const Column *aCol = pIdx->pTable->aCol;
+  for(i=0; i<pIdx->nColumn; i++){
+    i16 x = pIdx->aiColumn[i];
+    assert( x<pIdx->pTable->nCol );
+    wIndex += x<0 ? 1 : aCol[pIdx->aiColumn[i]].szEst;
+  }
+  pIdx->szIdxRow = sqlite3LogEst(wIndex*4);
+}
+
+/* Return true if value x is found any of the first nCol entries of aiCol[]
+*/
+static int hasColumn(const i16 *aiCol, int nCol, int x){
+  while( nCol-- > 0 ) if( x==*(aiCol++) ) return 1;
+  return 0;
+}
+
+/*
+** This routine runs at the end of parsing a CREATE TABLE statement that
+** has a WITHOUT ROWID clause.  The job of this routine is to convert both
+** internal schema data structures and the generated VDBE code so that they
+** are appropriate for a WITHOUT ROWID table instead of a rowid table.
+** Changes include:
+**
+**     (1)  Set all columns of the PRIMARY KEY schema object to be NOT NULL.
+**     (2)  Convert the OP_CreateTable into an OP_CreateIndex.  There is
+**          no rowid btree for a WITHOUT ROWID.  Instead, the canonical
+**          data storage is a covering index btree.
+**     (3)  Bypass the creation of the sqlite_master table entry
+**          for the PRIMARY KEY as the primary key index is now
+**          identified by the sqlite_master table entry of the table itself.
+**     (4)  Set the Index.tnum of the PRIMARY KEY Index object in the
+**          schema to the rootpage from the main table.
+**     (5)  Add all table columns to the PRIMARY KEY Index object
+**          so that the PRIMARY KEY is a covering index.  The surplus
+**          columns are part of KeyInfo.nXField and are not used for
+**          sorting or lookup or uniqueness checks.
+**     (6)  Replace the rowid tail on all automatically generated UNIQUE
+**          indices with the PRIMARY KEY columns.
+**
+** For virtual tables, only (1) is performed.
+*/
+static void convertToWithoutRowidTable(Parse *pParse, Table *pTab){
+  Index *pIdx;
+  Index *pPk;
+  int nPk;
+  int i, j;
+  sqlite3 *db = pParse->db;
+  Vdbe *v = pParse->pVdbe;
+
+  /* Mark every PRIMARY KEY column as NOT NULL (except for imposter tables)
+  */
+  if( !db->init.imposterTable ){
+    for(i=0; i<pTab->nCol; i++){
+      if( (pTab->aCol[i].colFlags & COLFLAG_PRIMKEY)!=0 ){
+        pTab->aCol[i].notNull = OE_Abort;
+      }
+    }
+  }
+
+  /* The remaining transformations only apply to b-tree tables, not to
+  ** virtual tables */
+  if( IN_DECLARE_VTAB ) return;
+
+  /* Convert the OP_CreateTable opcode that would normally create the
+  ** root-page for the table into an OP_CreateIndex opcode.  The index
+  ** created will become the PRIMARY KEY index.
+  */
+  if( pParse->addrCrTab ){
+    assert( v );
+    sqlite3VdbeChangeOpcode(v, pParse->addrCrTab, OP_CreateIndex);
+  }
+
+  /* Locate the PRIMARY KEY index.  Or, if this table was originally
+  ** an INTEGER PRIMARY KEY table, create a new PRIMARY KEY index. 
+  */
+  if( pTab->iPKey>=0 ){
+    ExprList *pList;
+    Token ipkToken;
+    sqlite3TokenInit(&ipkToken, pTab->aCol[pTab->iPKey].zName);
+    pList = sqlite3ExprListAppend(pParse, 0, 
+                  sqlite3ExprAlloc(db, TK_ID, &ipkToken, 0));
+    if( pList==0 ) return;
+    pList->a[0].sortOrder = pParse->iPkSortOrder;
+    assert( pParse->pNewTable==pTab );
+    sqlite3CreateIndex(pParse, 0, 0, 0, pList, pTab->keyConf, 0, 0, 0, 0,
+                       SQLITE_IDXTYPE_PRIMARYKEY);
+    if( db->mallocFailed ) return;
+    pPk = sqlite3PrimaryKeyIndex(pTab);
+    pTab->iPKey = -1;
+  }else{
+    pPk = sqlite3PrimaryKeyIndex(pTab);
+
+    /* Bypass the creation of the PRIMARY KEY btree and the sqlite_master
+    ** table entry. This is only required if currently generating VDBE
+    ** code for a CREATE TABLE (not when parsing one as part of reading
+    ** a database schema).  */
+    if( v ){
+      assert( db->init.busy==0 );
+      sqlite3VdbeChangeOpcode(v, pPk->tnum, OP_Goto);
+    }
+
+    /*
+    ** Remove all redundant columns from the PRIMARY KEY.  For example, change
+    ** "PRIMARY KEY(a,b,a,b,c,b,c,d)" into just "PRIMARY KEY(a,b,c,d)".  Later
+    ** code assumes the PRIMARY KEY contains no repeated columns.
+    */
+    for(i=j=1; i<pPk->nKeyCol; i++){
+      if( hasColumn(pPk->aiColumn, j, pPk->aiColumn[i]) ){
+        pPk->nColumn--;
+      }else{
+        pPk->aiColumn[j++] = pPk->aiColumn[i];
+      }
+    }
+    pPk->nKeyCol = j;
+  }
+  assert( pPk!=0 );
+  pPk->isCovering = 1;
+  if( !db->init.imposterTable ) pPk->uniqNotNull = 1;
+  nPk = pPk->nKeyCol;
+
+  /* The root page of the PRIMARY KEY is the table root page */
+  pPk->tnum = pTab->tnum;
+
+  /* Update the in-memory representation of all UNIQUE indices by converting
+  ** the final rowid column into one or more columns of the PRIMARY KEY.
+  */
+  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+    int n;
+    if( IsPrimaryKeyIndex(pIdx) ) continue;
+    for(i=n=0; i<nPk; i++){
+      if( !hasColumn(pIdx->aiColumn, pIdx->nKeyCol, pPk->aiColumn[i]) ) n++;
+    }
+    if( n==0 ){
+      /* This index is a superset of the primary key */
+      pIdx->nColumn = pIdx->nKeyCol;
+      continue;
+    }
+    if( resizeIndexObject(db, pIdx, pIdx->nKeyCol+n) ) return;
+    for(i=0, j=pIdx->nKeyCol; i<nPk; i++){
+      if( !hasColumn(pIdx->aiColumn, pIdx->nKeyCol, pPk->aiColumn[i]) ){
+        pIdx->aiColumn[j] = pPk->aiColumn[i];
+        pIdx->azColl[j] = pPk->azColl[i];
+        j++;
+      }
+    }
+    assert( pIdx->nColumn>=pIdx->nKeyCol+n );
+    assert( pIdx->nColumn>=j );
+  }
+
+  /* Add all table columns to the PRIMARY KEY index
+  */
+  if( nPk<pTab->nCol ){
+    if( resizeIndexObject(db, pPk, pTab->nCol) ) return;
+    for(i=0, j=nPk; i<pTab->nCol; i++){
+      if( !hasColumn(pPk->aiColumn, j, i) ){
+        assert( j<pPk->nColumn );
+        pPk->aiColumn[j] = i;
+        pPk->azColl[j] = sqlite3StrBINARY;
+        j++;
+      }
+    }
+    assert( pPk->nColumn==j );
+    assert( pTab->nCol==j );
+  }else{
+    pPk->nColumn = pTab->nCol;
+  }
+}
+
+/*
+** This routine is called to report the final ")" that terminates
+** a CREATE TABLE statement.
+**
+** The table structure that other action routines have been building
+** is added to the internal hash tables, assuming no errors have
+** occurred.
+**
+** An entry for the table is made in the master table on disk, unless
+** this is a temporary table or db->init.busy==1.  When db->init.busy==1
+** it means we are reading the sqlite_master table because we just
+** connected to the database or because the sqlite_master table has
+** recently changed, so the entry for this table already exists in
+** the sqlite_master table.  We do not want to create it again.
+**
+** If the pSelect argument is not NULL, it means that this routine
+** was called to create a table generated from a 
+** "CREATE TABLE ... AS SELECT ..." statement.  The column names of
+** the new table will match the result set of the SELECT.
+*/
+SQLITE_PRIVATE void sqlite3EndTable(
+  Parse *pParse,          /* Parse context */
+  Token *pCons,           /* The ',' token after the last column defn. */
+  Token *pEnd,            /* The ')' before options in the CREATE TABLE */
+  u8 tabOpts,             /* Extra table options. Usually 0. */
+  Select *pSelect         /* Select from a "CREATE ... AS SELECT" */
+){
+  Table *p;                 /* The new table */
+  sqlite3 *db = pParse->db; /* The database connection */
+  int iDb;                  /* Database in which the table lives */
+  Index *pIdx;              /* An implied index of the table */
+
+  if( pEnd==0 && pSelect==0 ){
+    return;
+  }
+  assert( !db->mallocFailed );
+  p = pParse->pNewTable;
+  if( p==0 ) return;
+
+  assert( !db->init.busy || !pSelect );
+
+  /* If the db->init.busy is 1 it means we are reading the SQL off the
+  ** "sqlite_master" or "sqlite_temp_master" table on the disk.
+  ** So do not write to the disk again.  Extract the root page number
+  ** for the table from the db->init.newTnum field.  (The page number
+  ** should have been put there by the sqliteOpenCb routine.)
+  **
+  ** If the root page number is 1, that means this is the sqlite_master
+  ** table itself.  So mark it read-only.
+  */
+  if( db->init.busy ){
+    p->tnum = db->init.newTnum;
+    if( p->tnum==1 ) p->tabFlags |= TF_Readonly;
+  }
+
+  /* Special processing for WITHOUT ROWID Tables */
+  if( tabOpts & TF_WithoutRowid ){
+    if( (p->tabFlags & TF_Autoincrement) ){
+      sqlite3ErrorMsg(pParse,
+          "AUTOINCREMENT not allowed on WITHOUT ROWID tables");
+      return;
+    }
+    if( (p->tabFlags & TF_HasPrimaryKey)==0 ){
+      sqlite3ErrorMsg(pParse, "PRIMARY KEY missing on table %s", p->zName);
+    }else{
+      p->tabFlags |= TF_WithoutRowid | TF_NoVisibleRowid;
+      convertToWithoutRowidTable(pParse, p);
+    }
+  }
+
+  iDb = sqlite3SchemaToIndex(db, p->pSchema);
+
+#ifndef SQLITE_OMIT_CHECK
+  /* Resolve names in all CHECK constraint expressions.
+  */
+  if( p->pCheck ){
+    sqlite3ResolveSelfReference(pParse, p, NC_IsCheck, 0, p->pCheck);
+  }
+#endif /* !defined(SQLITE_OMIT_CHECK) */
+
+  /* Estimate the average row size for the table and for all implied indices */
+  estimateTableWidth(p);
+  for(pIdx=p->pIndex; pIdx; pIdx=pIdx->pNext){
+    estimateIndexWidth(pIdx);
+  }
+
+  /* If not initializing, then create a record for the new table
+  ** in the SQLITE_MASTER table of the database.
+  **
+  ** If this is a TEMPORARY table, write the entry into the auxiliary
+  ** file instead of into the main database file.
+  */
+  if( !db->init.busy ){
+    int n;
+    Vdbe *v;
+    char *zType;    /* "view" or "table" */
+    char *zType2;   /* "VIEW" or "TABLE" */
+    char *zStmt;    /* Text of the CREATE TABLE or CREATE VIEW statement */
+
+    v = sqlite3GetVdbe(pParse);
+    if( NEVER(v==0) ) return;
+
+    sqlite3VdbeAddOp1(v, OP_Close, 0);
+
+    /* 
+    ** Initialize zType for the new view or table.
+    */
+    if( p->pSelect==0 ){
+      /* A regular table */
+      zType = "table";
+      zType2 = "TABLE";
+#ifndef SQLITE_OMIT_VIEW
+    }else{
+      /* A view */
+      zType = "view";
+      zType2 = "VIEW";
+#endif
+    }
+
+    /* If this is a CREATE TABLE xx AS SELECT ..., execute the SELECT
+    ** statement to populate the new table. The root-page number for the
+    ** new table is in register pParse->regRoot.
+    **
+    ** Once the SELECT has been coded by sqlite3Select(), it is in a
+    ** suitable state to query for the column names and types to be used
+    ** by the new table.
+    **
+    ** A shared-cache write-lock is not required to write to the new table,
+    ** as a schema-lock must have already been obtained to create it. Since
+    ** a schema-lock excludes all other database users, the write-lock would
+    ** be redundant.
+    */
+    if( pSelect ){
+      SelectDest dest;    /* Where the SELECT should store results */
+      int regYield;       /* Register holding co-routine entry-point */
+      int addrTop;        /* Top of the co-routine */
+      int regRec;         /* A record to be insert into the new table */
+      int regRowid;       /* Rowid of the next row to insert */
+      int addrInsLoop;    /* Top of the loop for inserting rows */
+      Table *pSelTab;     /* A table that describes the SELECT results */
+
+      regYield = ++pParse->nMem;
+      regRec = ++pParse->nMem;
+      regRowid = ++pParse->nMem;
+      assert(pParse->nTab==1);
+      sqlite3MayAbort(pParse);
+      sqlite3VdbeAddOp3(v, OP_OpenWrite, 1, pParse->regRoot, iDb);
+      sqlite3VdbeChangeP5(v, OPFLAG_P2ISREG);
+      pParse->nTab = 2;
+      addrTop = sqlite3VdbeCurrentAddr(v) + 1;
+      sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, addrTop);
+      sqlite3SelectDestInit(&dest, SRT_Coroutine, regYield);
+      sqlite3Select(pParse, pSelect, &dest);
+      sqlite3VdbeEndCoroutine(v, regYield);
+      sqlite3VdbeJumpHere(v, addrTop - 1);
+      if( pParse->nErr ) return;
+      pSelTab = sqlite3ResultSetOfSelect(pParse, pSelect);
+      if( pSelTab==0 ) return;
+      assert( p->aCol==0 );
+      p->nCol = pSelTab->nCol;
+      p->aCol = pSelTab->aCol;
+      pSelTab->nCol = 0;
+      pSelTab->aCol = 0;
+      sqlite3DeleteTable(db, pSelTab);
+      addrInsLoop = sqlite3VdbeAddOp1(v, OP_Yield, dest.iSDParm);
+      VdbeCoverage(v);
+      sqlite3VdbeAddOp3(v, OP_MakeRecord, dest.iSdst, dest.nSdst, regRec);
+      sqlite3TableAffinity(v, p, 0);
+      sqlite3VdbeAddOp2(v, OP_NewRowid, 1, regRowid);
+      sqlite3VdbeAddOp3(v, OP_Insert, 1, regRec, regRowid);
+      sqlite3VdbeGoto(v, addrInsLoop);
+      sqlite3VdbeJumpHere(v, addrInsLoop);
+      sqlite3VdbeAddOp1(v, OP_Close, 1);
+    }
+
+    /* Compute the complete text of the CREATE statement */
+    if( pSelect ){
+      zStmt = createTableStmt(db, p);
+    }else{
+      Token *pEnd2 = tabOpts ? &pParse->sLastToken : pEnd;
+      n = (int)(pEnd2->z - pParse->sNameToken.z);
+      if( pEnd2->z[0]!=';' ) n += pEnd2->n;
+      zStmt = sqlite3MPrintf(db, 
+          "CREATE %s %.*s", zType2, n, pParse->sNameToken.z
+      );
+    }
+
+    /* A slot for the record has already been allocated in the 
+    ** SQLITE_MASTER table.  We just need to update that slot with all
+    ** the information we've collected.
+    */
+    sqlite3NestedParse(pParse,
+      "UPDATE %Q.%s "
+         "SET type='%s', name=%Q, tbl_name=%Q, rootpage=#%d, sql=%Q "
+       "WHERE rowid=#%d",
+      db->aDb[iDb].zDbSName, SCHEMA_TABLE(iDb),
+      zType,
+      p->zName,
+      p->zName,
+      pParse->regRoot,
+      zStmt,
+      pParse->regRowid
+    );
+    sqlite3DbFree(db, zStmt);
+    sqlite3ChangeCookie(pParse, iDb);
+
+#ifndef SQLITE_OMIT_AUTOINCREMENT
+    /* Check to see if we need to create an sqlite_sequence table for
+    ** keeping track of autoincrement keys.
+    */
+    if( (p->tabFlags & TF_Autoincrement)!=0 ){
+      Db *pDb = &db->aDb[iDb];
+      assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+      if( pDb->pSchema->pSeqTab==0 ){
+        sqlite3NestedParse(pParse,
+          "CREATE TABLE %Q.sqlite_sequence(name,seq)",
+          pDb->zDbSName
+        );
+      }
+    }
+#endif
+
+    /* Reparse everything to update our internal data structures */
+    sqlite3VdbeAddParseSchemaOp(v, iDb,
+           sqlite3MPrintf(db, "tbl_name='%q' AND type!='trigger'", p->zName));
+  }
+
+
+  /* Add the table to the in-memory representation of the database.
+  */
+  if( db->init.busy ){
+    Table *pOld;
+    Schema *pSchema = p->pSchema;
+    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+    pOld = sqlite3HashInsert(&pSchema->tblHash, p->zName, p);
+    if( pOld ){
+      assert( p==pOld );  /* Malloc must have failed inside HashInsert() */
+      sqlite3OomFault(db);
+      return;
+    }
+    pParse->pNewTable = 0;
+    db->flags |= SQLITE_InternChanges;
+
+#ifndef SQLITE_OMIT_ALTERTABLE
+    if( !p->pSelect ){
+      const char *zName = (const char *)pParse->sNameToken.z;
+      int nName;
+      assert( !pSelect && pCons && pEnd );
+      if( pCons->z==0 ){
+        pCons = pEnd;
+      }
+      nName = (int)((const char *)pCons->z - zName);
+      p->addColOffset = 13 + sqlite3Utf8CharLen(zName, nName);
+    }
+#endif
+  }
+}
+
+#ifndef SQLITE_OMIT_VIEW
+/*
+** The parser calls this routine in order to create a new VIEW
+*/
+SQLITE_PRIVATE void sqlite3CreateView(
+  Parse *pParse,     /* The parsing context */
+  Token *pBegin,     /* The CREATE token that begins the statement */
+  Token *pName1,     /* The token that holds the name of the view */
+  Token *pName2,     /* The token that holds the name of the view */
+  ExprList *pCNames, /* Optional list of view column names */
+  Select *pSelect,   /* A SELECT statement that will become the new view */
+  int isTemp,        /* TRUE for a TEMPORARY view */
+  int noErr          /* Suppress error messages if VIEW already exists */
+){
+  Table *p;
+  int n;
+  const char *z;
+  Token sEnd;
+  DbFixer sFix;
+  Token *pName = 0;
+  int iDb;
+  sqlite3 *db = pParse->db;
+
+  if( pParse->nVar>0 ){
+    sqlite3ErrorMsg(pParse, "parameters are not allowed in views");
+    goto create_view_fail;
+  }
+  sqlite3StartTable(pParse, pName1, pName2, isTemp, 1, 0, noErr);
+  p = pParse->pNewTable;
+  if( p==0 || pParse->nErr ) goto create_view_fail;
+  sqlite3TwoPartName(pParse, pName1, pName2, &pName);
+  iDb = sqlite3SchemaToIndex(db, p->pSchema);
+  sqlite3FixInit(&sFix, pParse, iDb, "view", pName);
+  if( sqlite3FixSelect(&sFix, pSelect) ) goto create_view_fail;
+
+  /* Make a copy of the entire SELECT statement that defines the view.
+  ** This will force all the Expr.token.z values to be dynamically
+  ** allocated rather than point to the input string - which means that
+  ** they will persist after the current sqlite3_exec() call returns.
+  */
+  p->pSelect = sqlite3SelectDup(db, pSelect, EXPRDUP_REDUCE);
+  p->pCheck = sqlite3ExprListDup(db, pCNames, EXPRDUP_REDUCE);
+  if( db->mallocFailed ) goto create_view_fail;
+
+  /* Locate the end of the CREATE VIEW statement.  Make sEnd point to
+  ** the end.
+  */
+  sEnd = pParse->sLastToken;
+  assert( sEnd.z[0]!=0 );
+  if( sEnd.z[0]!=';' ){
+    sEnd.z += sEnd.n;
+  }
+  sEnd.n = 0;
+  n = (int)(sEnd.z - pBegin->z);
+  assert( n>0 );
+  z = pBegin->z;
+  while( sqlite3Isspace(z[n-1]) ){ n--; }
+  sEnd.z = &z[n-1];
+  sEnd.n = 1;
+
+  /* Use sqlite3EndTable() to add the view to the SQLITE_MASTER table */
+  sqlite3EndTable(pParse, 0, &sEnd, 0, 0);
+
+create_view_fail:
+  sqlite3SelectDelete(db, pSelect);
+  sqlite3ExprListDelete(db, pCNames);
+  return;
+}
+#endif /* SQLITE_OMIT_VIEW */
+
+#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_VIRTUALTABLE)
+/*
+** The Table structure pTable is really a VIEW.  Fill in the names of
+** the columns of the view in the pTable structure.  Return the number
+** of errors.  If an error is seen leave an error message in pParse->zErrMsg.
+*/
+SQLITE_PRIVATE int sqlite3ViewGetColumnNames(Parse *pParse, Table *pTable){
+  Table *pSelTab;   /* A fake table from which we get the result set */
+  Select *pSel;     /* Copy of the SELECT that implements the view */
+  int nErr = 0;     /* Number of errors encountered */
+  int n;            /* Temporarily holds the number of cursors assigned */
+  sqlite3 *db = pParse->db;  /* Database connection for malloc errors */
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  sqlite3_xauth xAuth;       /* Saved xAuth pointer */
+#endif
+
+  assert( pTable );
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  if( sqlite3VtabCallConnect(pParse, pTable) ){
+    return SQLITE_ERROR;
+  }
+  if( IsVirtual(pTable) ) return 0;
+#endif
+
+#ifndef SQLITE_OMIT_VIEW
+  /* A positive nCol means the columns names for this view are
+  ** already known.
+  */
+  if( pTable->nCol>0 ) return 0;
+
+  /* A negative nCol is a special marker meaning that we are currently
+  ** trying to compute the column names.  If we enter this routine with
+  ** a negative nCol, it means two or more views form a loop, like this:
+  **
+  **     CREATE VIEW one AS SELECT * FROM two;
+  **     CREATE VIEW two AS SELECT * FROM one;
+  **
+  ** Actually, the error above is now caught prior to reaching this point.
+  ** But the following test is still important as it does come up
+  ** in the following:
+  ** 
+  **     CREATE TABLE main.ex1(a);
+  **     CREATE TEMP VIEW ex1 AS SELECT a FROM ex1;
+  **     SELECT * FROM temp.ex1;
+  */
+  if( pTable->nCol<0 ){
+    sqlite3ErrorMsg(pParse, "view %s is circularly defined", pTable->zName);
+    return 1;
+  }
+  assert( pTable->nCol>=0 );
+
+  /* If we get this far, it means we need to compute the table names.
+  ** Note that the call to sqlite3ResultSetOfSelect() will expand any
+  ** "*" elements in the results set of the view and will assign cursors
+  ** to the elements of the FROM clause.  But we do not want these changes
+  ** to be permanent.  So the computation is done on a copy of the SELECT
+  ** statement that defines the view.
+  */
+  assert( pTable->pSelect );
+  pSel = sqlite3SelectDup(db, pTable->pSelect, 0);
+  if( pSel ){
+    n = pParse->nTab;
+    sqlite3SrcListAssignCursors(pParse, pSel->pSrc);
+    pTable->nCol = -1;
+    db->lookaside.bDisable++;
+#ifndef SQLITE_OMIT_AUTHORIZATION
+    xAuth = db->xAuth;
+    db->xAuth = 0;
+    pSelTab = sqlite3ResultSetOfSelect(pParse, pSel);
+    db->xAuth = xAuth;
+#else
+    pSelTab = sqlite3ResultSetOfSelect(pParse, pSel);
+#endif
+    pParse->nTab = n;
+    if( pTable->pCheck ){
+      /* CREATE VIEW name(arglist) AS ...
+      ** The names of the columns in the table are taken from
+      ** arglist which is stored in pTable->pCheck.  The pCheck field
+      ** normally holds CHECK constraints on an ordinary table, but for
+      ** a VIEW it holds the list of column names.
+      */
+      sqlite3ColumnsFromExprList(pParse, pTable->pCheck, 
+                                 &pTable->nCol, &pTable->aCol);
+      if( db->mallocFailed==0 
+       && pParse->nErr==0
+       && pTable->nCol==pSel->pEList->nExpr
+      ){
+        sqlite3SelectAddColumnTypeAndCollation(pParse, pTable, pSel);
+      }
+    }else if( pSelTab ){
+      /* CREATE VIEW name AS...  without an argument list.  Construct
+      ** the column names from the SELECT statement that defines the view.
+      */
+      assert( pTable->aCol==0 );
+      pTable->nCol = pSelTab->nCol;
+      pTable->aCol = pSelTab->aCol;
+      pSelTab->nCol = 0;
+      pSelTab->aCol = 0;
+      assert( sqlite3SchemaMutexHeld(db, 0, pTable->pSchema) );
+    }else{
+      pTable->nCol = 0;
+      nErr++;
+    }
+    sqlite3DeleteTable(db, pSelTab);
+    sqlite3SelectDelete(db, pSel);
+    db->lookaside.bDisable--;
+  } else {
+    nErr++;
+  }
+  pTable->pSchema->schemaFlags |= DB_UnresetViews;
+#endif /* SQLITE_OMIT_VIEW */
+  return nErr;  
+}
+#endif /* !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_VIRTUALTABLE) */
+
+#ifndef SQLITE_OMIT_VIEW
+/*
+** Clear the column names from every VIEW in database idx.
+*/
+static void sqliteViewResetAll(sqlite3 *db, int idx){
+  HashElem *i;
+  assert( sqlite3SchemaMutexHeld(db, idx, 0) );
+  if( !DbHasProperty(db, idx, DB_UnresetViews) ) return;
+  for(i=sqliteHashFirst(&db->aDb[idx].pSchema->tblHash); i;i=sqliteHashNext(i)){
+    Table *pTab = sqliteHashData(i);
+    if( pTab->pSelect ){
+      sqlite3DeleteColumnNames(db, pTab);
+      pTab->aCol = 0;
+      pTab->nCol = 0;
+    }
+  }
+  DbClearProperty(db, idx, DB_UnresetViews);
+}
+#else
+# define sqliteViewResetAll(A,B)
+#endif /* SQLITE_OMIT_VIEW */
+
+/*
+** This function is called by the VDBE to adjust the internal schema
+** used by SQLite when the btree layer moves a table root page. The
+** root-page of a table or index in database iDb has changed from iFrom
+** to iTo.
+**
+** Ticket #1728:  The symbol table might still contain information
+** on tables and/or indices that are the process of being deleted.
+** If you are unlucky, one of those deleted indices or tables might
+** have the same rootpage number as the real table or index that is
+** being moved.  So we cannot stop searching after the first match 
+** because the first match might be for one of the deleted indices
+** or tables and not the table/index that is actually being moved.
+** We must continue looping until all tables and indices with
+** rootpage==iFrom have been converted to have a rootpage of iTo
+** in order to be certain that we got the right one.
+*/
+#ifndef SQLITE_OMIT_AUTOVACUUM
+SQLITE_PRIVATE void sqlite3RootPageMoved(sqlite3 *db, int iDb, int iFrom, int iTo){
+  HashElem *pElem;
+  Hash *pHash;
+  Db *pDb;
+
+  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+  pDb = &db->aDb[iDb];
+  pHash = &pDb->pSchema->tblHash;
+  for(pElem=sqliteHashFirst(pHash); pElem; pElem=sqliteHashNext(pElem)){
+    Table *pTab = sqliteHashData(pElem);
+    if( pTab->tnum==iFrom ){
+      pTab->tnum = iTo;
+    }
+  }
+  pHash = &pDb->pSchema->idxHash;
+  for(pElem=sqliteHashFirst(pHash); pElem; pElem=sqliteHashNext(pElem)){
+    Index *pIdx = sqliteHashData(pElem);
+    if( pIdx->tnum==iFrom ){
+      pIdx->tnum = iTo;
+    }
+  }
+}
+#endif
+
+/*
+** Write code to erase the table with root-page iTable from database iDb.
+** Also write code to modify the sqlite_master table and internal schema
+** if a root-page of another table is moved by the btree-layer whilst
+** erasing iTable (this can happen with an auto-vacuum database).
+*/ 
+static void destroyRootPage(Parse *pParse, int iTable, int iDb){
+  Vdbe *v = sqlite3GetVdbe(pParse);
+  int r1 = sqlite3GetTempReg(pParse);
+  assert( iTable>1 );
+  sqlite3VdbeAddOp3(v, OP_Destroy, iTable, r1, iDb);
+  sqlite3MayAbort(pParse);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+  /* OP_Destroy stores an in integer r1. If this integer
+  ** is non-zero, then it is the root page number of a table moved to
+  ** location iTable. The following code modifies the sqlite_master table to
+  ** reflect this.
+  **
+  ** The "#NNN" in the SQL is a special constant that means whatever value
+  ** is in register NNN.  See grammar rules associated with the TK_REGISTER
+  ** token for additional information.
+  */
+  sqlite3NestedParse(pParse, 
+     "UPDATE %Q.%s SET rootpage=%d WHERE #%d AND rootpage=#%d",
+     pParse->db->aDb[iDb].zDbSName, SCHEMA_TABLE(iDb), iTable, r1, r1);
+#endif
+  sqlite3ReleaseTempReg(pParse, r1);
+}
+
+/*
+** Write VDBE code to erase table pTab and all associated indices on disk.
+** Code to update the sqlite_master tables and internal schema definitions
+** in case a root-page belonging to another table is moved by the btree layer
+** is also added (this can happen with an auto-vacuum database).
+*/
+static void destroyTable(Parse *pParse, Table *pTab){
+#ifdef SQLITE_OMIT_AUTOVACUUM
+  Index *pIdx;
+  int iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
+  destroyRootPage(pParse, pTab->tnum, iDb);
+  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+    destroyRootPage(pParse, pIdx->tnum, iDb);
+  }
+#else
+  /* If the database may be auto-vacuum capable (if SQLITE_OMIT_AUTOVACUUM
+  ** is not defined), then it is important to call OP_Destroy on the
+  ** table and index root-pages in order, starting with the numerically 
+  ** largest root-page number. This guarantees that none of the root-pages
+  ** to be destroyed is relocated by an earlier OP_Destroy. i.e. if the
+  ** following were coded:
+  **
+  ** OP_Destroy 4 0
+  ** ...
+  ** OP_Destroy 5 0
+  **
+  ** and root page 5 happened to be the largest root-page number in the
+  ** database, then root page 5 would be moved to page 4 by the 
+  ** "OP_Destroy 4 0" opcode. The subsequent "OP_Destroy 5 0" would hit
+  ** a free-list page.
+  */
+  int iTab = pTab->tnum;
+  int iDestroyed = 0;
+
+  while( 1 ){
+    Index *pIdx;
+    int iLargest = 0;
+
+    if( iDestroyed==0 || iTab<iDestroyed ){
+      iLargest = iTab;
+    }
+    for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+      int iIdx = pIdx->tnum;
+      assert( pIdx->pSchema==pTab->pSchema );
+      if( (iDestroyed==0 || (iIdx<iDestroyed)) && iIdx>iLargest ){
+        iLargest = iIdx;
+      }
+    }
+    if( iLargest==0 ){
+      return;
+    }else{
+      int iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
+      assert( iDb>=0 && iDb<pParse->db->nDb );
+      destroyRootPage(pParse, iLargest, iDb);
+      iDestroyed = iLargest;
+    }
+  }
+#endif
+}
+
+/*
+** Remove entries from the sqlite_statN tables (for N in (1,2,3))
+** after a DROP INDEX or DROP TABLE command.
+*/
+static void sqlite3ClearStatTables(
+  Parse *pParse,         /* The parsing context */
+  int iDb,               /* The database number */
+  const char *zType,     /* "idx" or "tbl" */
+  const char *zName      /* Name of index or table */
+){
+  int i;
+  const char *zDbName = pParse->db->aDb[iDb].zDbSName;
+  for(i=1; i<=4; i++){
+    char zTab[24];
+    sqlite3_snprintf(sizeof(zTab),zTab,"sqlite_stat%d",i);
+    if( sqlite3FindTable(pParse->db, zTab, zDbName) ){
+      sqlite3NestedParse(pParse,
+        "DELETE FROM %Q.%s WHERE %s=%Q",
+        zDbName, zTab, zType, zName
+      );
+    }
+  }
+}
+
+/*
+** Generate code to drop a table.
+*/
+SQLITE_PRIVATE void sqlite3CodeDropTable(Parse *pParse, Table *pTab, int iDb, int isView){
+  Vdbe *v;
+  sqlite3 *db = pParse->db;
+  Trigger *pTrigger;
+  Db *pDb = &db->aDb[iDb];
+
+  v = sqlite3GetVdbe(pParse);
+  assert( v!=0 );
+  sqlite3BeginWriteOperation(pParse, 1, iDb);
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  if( IsVirtual(pTab) ){
+    sqlite3VdbeAddOp0(v, OP_VBegin);
+  }
+#endif
+
+  /* Drop all triggers associated with the table being dropped. Code
+  ** is generated to remove entries from sqlite_master and/or
+  ** sqlite_temp_master if required.
+  */
+  pTrigger = sqlite3TriggerList(pParse, pTab);
+  while( pTrigger ){
+    assert( pTrigger->pSchema==pTab->pSchema || 
+        pTrigger->pSchema==db->aDb[1].pSchema );
+    sqlite3DropTriggerPtr(pParse, pTrigger);
+    pTrigger = pTrigger->pNext;
+  }
+
+#ifndef SQLITE_OMIT_AUTOINCREMENT
+  /* Remove any entries of the sqlite_sequence table associated with
+  ** the table being dropped. This is done before the table is dropped
+  ** at the btree level, in case the sqlite_sequence table needs to
+  ** move as a result of the drop (can happen in auto-vacuum mode).
+  */
+  if( pTab->tabFlags & TF_Autoincrement ){
+    sqlite3NestedParse(pParse,
+      "DELETE FROM %Q.sqlite_sequence WHERE name=%Q",
+      pDb->zDbSName, pTab->zName
+    );
+  }
+#endif
+
+  /* Drop all SQLITE_MASTER table and index entries that refer to the
+  ** table. The program name loops through the master table and deletes
+  ** every row that refers to a table of the same name as the one being
+  ** dropped. Triggers are handled separately because a trigger can be
+  ** created in the temp database that refers to a table in another
+  ** database.
+  */
+  sqlite3NestedParse(pParse, 
+      "DELETE FROM %Q.%s WHERE tbl_name=%Q and type!='trigger'",
+      pDb->zDbSName, SCHEMA_TABLE(iDb), pTab->zName);
+  if( !isView && !IsVirtual(pTab) ){
+    destroyTable(pParse, pTab);
+  }
+
+  /* Remove the table entry from SQLite's internal schema and modify
+  ** the schema cookie.
+  */
+  if( IsVirtual(pTab) ){
+    sqlite3VdbeAddOp4(v, OP_VDestroy, iDb, 0, 0, pTab->zName, 0);
+  }
+  sqlite3VdbeAddOp4(v, OP_DropTable, iDb, 0, 0, pTab->zName, 0);
+  sqlite3ChangeCookie(pParse, iDb);
+  sqliteViewResetAll(db, iDb);
+}
+
+/*
+** This routine is called to do the work of a DROP TABLE statement.
+** pName is the name of the table to be dropped.
+*/
+SQLITE_PRIVATE void sqlite3DropTable(Parse *pParse, SrcList *pName, int isView, int noErr){
+  Table *pTab;
+  Vdbe *v;
+  sqlite3 *db = pParse->db;
+  int iDb;
+
+  if( db->mallocFailed ){
+    goto exit_drop_table;
+  }
+  assert( pParse->nErr==0 );
+  assert( pName->nSrc==1 );
+  if( sqlite3ReadSchema(pParse) ) goto exit_drop_table;
+  if( noErr ) db->suppressErr++;
+  assert( isView==0 || isView==LOCATE_VIEW );
+  pTab = sqlite3LocateTableItem(pParse, isView, &pName->a[0]);
+  if( noErr ) db->suppressErr--;
+
+  if( pTab==0 ){
+    if( noErr ) sqlite3CodeVerifyNamedSchema(pParse, pName->a[0].zDatabase);
+    goto exit_drop_table;
+  }
+  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+  assert( iDb>=0 && iDb<db->nDb );
+
+  /* If pTab is a virtual table, call ViewGetColumnNames() to ensure
+  ** it is initialized.
+  */
+  if( IsVirtual(pTab) && sqlite3ViewGetColumnNames(pParse, pTab) ){
+    goto exit_drop_table;
+  }
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  {
+    int code;
+    const char *zTab = SCHEMA_TABLE(iDb);
+    const char *zDb = db->aDb[iDb].zDbSName;
+    const char *zArg2 = 0;
+    if( sqlite3AuthCheck(pParse, SQLITE_DELETE, zTab, 0, zDb)){
+      goto exit_drop_table;
+    }
+    if( isView ){
+      if( !OMIT_TEMPDB && iDb==1 ){
+        code = SQLITE_DROP_TEMP_VIEW;
+      }else{
+        code = SQLITE_DROP_VIEW;
+      }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    }else if( IsVirtual(pTab) ){
+      code = SQLITE_DROP_VTABLE;
+      zArg2 = sqlite3GetVTable(db, pTab)->pMod->zName;
+#endif
+    }else{
+      if( !OMIT_TEMPDB && iDb==1 ){
+        code = SQLITE_DROP_TEMP_TABLE;
+      }else{
+        code = SQLITE_DROP_TABLE;
+      }
+    }
+    if( sqlite3AuthCheck(pParse, code, pTab->zName, zArg2, zDb) ){
+      goto exit_drop_table;
+    }
+    if( sqlite3AuthCheck(pParse, SQLITE_DELETE, pTab->zName, 0, zDb) ){
+      goto exit_drop_table;
+    }
+  }
+#endif
+  if( sqlite3StrNICmp(pTab->zName, "sqlite_", 7)==0 
+    && sqlite3StrNICmp(pTab->zName, "sqlite_stat", 11)!=0 ){
+    sqlite3ErrorMsg(pParse, "table %s may not be dropped", pTab->zName);
+    goto exit_drop_table;
+  }
+
+#ifndef SQLITE_OMIT_VIEW
+  /* Ensure DROP TABLE is not used on a view, and DROP VIEW is not used
+  ** on a table.
+  */
+  if( isView && pTab->pSelect==0 ){
+    sqlite3ErrorMsg(pParse, "use DROP TABLE to delete table %s", pTab->zName);
+    goto exit_drop_table;
+  }
+  if( !isView && pTab->pSelect ){
+    sqlite3ErrorMsg(pParse, "use DROP VIEW to delete view %s", pTab->zName);
+    goto exit_drop_table;
+  }
+#endif
+
+  /* Generate code to remove the table from the master table
+  ** on disk.
+  */
+  v = sqlite3GetVdbe(pParse);
+  if( v ){
+    sqlite3BeginWriteOperation(pParse, 1, iDb);
+    sqlite3ClearStatTables(pParse, iDb, "tbl", pTab->zName);
+    sqlite3FkDropTable(pParse, pName, pTab);
+    sqlite3CodeDropTable(pParse, pTab, iDb, isView);
+  }
+
+exit_drop_table:
+  sqlite3SrcListDelete(db, pName);
+}
+
+/*
+** This routine is called to create a new foreign key on the table
+** currently under construction.  pFromCol determines which columns
+** in the current table point to the foreign key.  If pFromCol==0 then
+** connect the key to the last column inserted.  pTo is the name of
+** the table referred to (a.k.a the "parent" table).  pToCol is a list
+** of tables in the parent pTo table.  flags contains all
+** information about the conflict resolution algorithms specified
+** in the ON DELETE, ON UPDATE and ON INSERT clauses.
+**
+** An FKey structure is created and added to the table currently
+** under construction in the pParse->pNewTable field.
+**
+** The foreign key is set for IMMEDIATE processing.  A subsequent call
+** to sqlite3DeferForeignKey() might change this to DEFERRED.
+*/
+SQLITE_PRIVATE void sqlite3CreateForeignKey(
+  Parse *pParse,       /* Parsing context */
+  ExprList *pFromCol,  /* Columns in this table that point to other table */
+  Token *pTo,          /* Name of the other table */
+  ExprList *pToCol,    /* Columns in the other table */
+  int flags            /* Conflict resolution algorithms. */
+){
+  sqlite3 *db = pParse->db;
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+  FKey *pFKey = 0;
+  FKey *pNextTo;
+  Table *p = pParse->pNewTable;
+  int nByte;
+  int i;
+  int nCol;
+  char *z;
+
+  assert( pTo!=0 );
+  if( p==0 || IN_DECLARE_VTAB ) goto fk_end;
+  if( pFromCol==0 ){
+    int iCol = p->nCol-1;
+    if( NEVER(iCol<0) ) goto fk_end;
+    if( pToCol && pToCol->nExpr!=1 ){
+      sqlite3ErrorMsg(pParse, "foreign key on %s"
+         " should reference only one column of table %T",
+         p->aCol[iCol].zName, pTo);
+      goto fk_end;
+    }
+    nCol = 1;
+  }else if( pToCol && pToCol->nExpr!=pFromCol->nExpr ){
+    sqlite3ErrorMsg(pParse,
+        "number of columns in foreign key does not match the number of "
+        "columns in the referenced table");
+    goto fk_end;
+  }else{
+    nCol = pFromCol->nExpr;
+  }
+  nByte = sizeof(*pFKey) + (nCol-1)*sizeof(pFKey->aCol[0]) + pTo->n + 1;
+  if( pToCol ){
+    for(i=0; i<pToCol->nExpr; i++){
+      nByte += sqlite3Strlen30(pToCol->a[i].zName) + 1;
+    }
+  }
+  pFKey = sqlite3DbMallocZero(db, nByte );
+  if( pFKey==0 ){
+    goto fk_end;
+  }
+  pFKey->pFrom = p;
+  pFKey->pNextFrom = p->pFKey;
+  z = (char*)&pFKey->aCol[nCol];
+  pFKey->zTo = z;
+  memcpy(z, pTo->z, pTo->n);
+  z[pTo->n] = 0;
+  sqlite3Dequote(z);
+  z += pTo->n+1;
+  pFKey->nCol = nCol;
+  if( pFromCol==0 ){
+    pFKey->aCol[0].iFrom = p->nCol-1;
+  }else{
+    for(i=0; i<nCol; i++){
+      int j;
+      for(j=0; j<p->nCol; j++){
+        if( sqlite3StrICmp(p->aCol[j].zName, pFromCol->a[i].zName)==0 ){
+          pFKey->aCol[i].iFrom = j;
+          break;
+        }
+      }
+      if( j>=p->nCol ){
+        sqlite3ErrorMsg(pParse, 
+          "unknown column \"%s\" in foreign key definition", 
+          pFromCol->a[i].zName);
+        goto fk_end;
+      }
+    }
+  }
+  if( pToCol ){
+    for(i=0; i<nCol; i++){
+      int n = sqlite3Strlen30(pToCol->a[i].zName);
+      pFKey->aCol[i].zCol = z;
+      memcpy(z, pToCol->a[i].zName, n);
+      z[n] = 0;
+      z += n+1;
+    }
+  }
+  pFKey->isDeferred = 0;
+  pFKey->aAction[0] = (u8)(flags & 0xff);            /* ON DELETE action */
+  pFKey->aAction[1] = (u8)((flags >> 8 ) & 0xff);    /* ON UPDATE action */
+
+  assert( sqlite3SchemaMutexHeld(db, 0, p->pSchema) );
+  pNextTo = (FKey *)sqlite3HashInsert(&p->pSchema->fkeyHash, 
+      pFKey->zTo, (void *)pFKey
+  );
+  if( pNextTo==pFKey ){
+    sqlite3OomFault(db);
+    goto fk_end;
+  }
+  if( pNextTo ){
+    assert( pNextTo->pPrevTo==0 );
+    pFKey->pNextTo = pNextTo;
+    pNextTo->pPrevTo = pFKey;
+  }
+
+  /* Link the foreign key to the table as the last step.
+  */
+  p->pFKey = pFKey;
+  pFKey = 0;
+
+fk_end:
+  sqlite3DbFree(db, pFKey);
+#endif /* !defined(SQLITE_OMIT_FOREIGN_KEY) */
+  sqlite3ExprListDelete(db, pFromCol);
+  sqlite3ExprListDelete(db, pToCol);
+}
+
+/*
+** This routine is called when an INITIALLY IMMEDIATE or INITIALLY DEFERRED
+** clause is seen as part of a foreign key definition.  The isDeferred
+** parameter is 1 for INITIALLY DEFERRED and 0 for INITIALLY IMMEDIATE.
+** The behavior of the most recently created foreign key is adjusted
+** accordingly.
+*/
+SQLITE_PRIVATE void sqlite3DeferForeignKey(Parse *pParse, int isDeferred){
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+  Table *pTab;
+  FKey *pFKey;
+  if( (pTab = pParse->pNewTable)==0 || (pFKey = pTab->pFKey)==0 ) return;
+  assert( isDeferred==0 || isDeferred==1 ); /* EV: R-30323-21917 */
+  pFKey->isDeferred = (u8)isDeferred;
+#endif
+}
+
+/*
+** Generate code that will erase and refill index *pIdx.  This is
+** used to initialize a newly created index or to recompute the
+** content of an index in response to a REINDEX command.
+**
+** if memRootPage is not negative, it means that the index is newly
+** created.  The register specified by memRootPage contains the
+** root page number of the index.  If memRootPage is negative, then
+** the index already exists and must be cleared before being refilled and
+** the root page number of the index is taken from pIndex->tnum.
+*/
+static void sqlite3RefillIndex(Parse *pParse, Index *pIndex, int memRootPage){
+  Table *pTab = pIndex->pTable;  /* The table that is indexed */
+  int iTab = pParse->nTab++;     /* Btree cursor used for pTab */
+  int iIdx = pParse->nTab++;     /* Btree cursor used for pIndex */
+  int iSorter;                   /* Cursor opened by OpenSorter (if in use) */
+  int addr1;                     /* Address of top of loop */
+  int addr2;                     /* Address to jump to for next iteration */
+  int tnum;                      /* Root page of index */
+  int iPartIdxLabel;             /* Jump to this label to skip a row */
+  Vdbe *v;                       /* Generate code into this virtual machine */
+  KeyInfo *pKey;                 /* KeyInfo for index */
+  int regRecord;                 /* Register holding assembled index record */
+  sqlite3 *db = pParse->db;      /* The database connection */
+  int iDb = sqlite3SchemaToIndex(db, pIndex->pSchema);
+
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  if( sqlite3AuthCheck(pParse, SQLITE_REINDEX, pIndex->zName, 0,
+      db->aDb[iDb].zDbSName ) ){
+    return;
+  }
+#endif
+
+  /* Require a write-lock on the table to perform this operation */
+  sqlite3TableLock(pParse, iDb, pTab->tnum, 1, pTab->zName);
+
+  v = sqlite3GetVdbe(pParse);
+  if( v==0 ) return;
+  if( memRootPage>=0 ){
+    tnum = memRootPage;
+  }else{
+    tnum = pIndex->tnum;
+  }
+  pKey = sqlite3KeyInfoOfIndex(pParse, pIndex);
+  assert( pKey!=0 || db->mallocFailed || pParse->nErr );
+
+  /* Open the sorter cursor if we are to use one. */
+  iSorter = pParse->nTab++;
+  sqlite3VdbeAddOp4(v, OP_SorterOpen, iSorter, 0, pIndex->nKeyCol, (char*)
+                    sqlite3KeyInfoRef(pKey), P4_KEYINFO);
+
+  /* Open the table. Loop through all rows of the table, inserting index
+  ** records into the sorter. */
+  sqlite3OpenTable(pParse, iTab, iDb, pTab, OP_OpenRead);
+  addr1 = sqlite3VdbeAddOp2(v, OP_Rewind, iTab, 0); VdbeCoverage(v);
+  regRecord = sqlite3GetTempReg(pParse);
+
+  sqlite3GenerateIndexKey(pParse,pIndex,iTab,regRecord,0,&iPartIdxLabel,0,0);
+  sqlite3VdbeAddOp2(v, OP_SorterInsert, iSorter, regRecord);
+  sqlite3ResolvePartIdxLabel(pParse, iPartIdxLabel);
+  sqlite3VdbeAddOp2(v, OP_Next, iTab, addr1+1); VdbeCoverage(v);
+  sqlite3VdbeJumpHere(v, addr1);
+  if( memRootPage<0 ) sqlite3VdbeAddOp2(v, OP_Clear, tnum, iDb);
+  sqlite3VdbeAddOp4(v, OP_OpenWrite, iIdx, tnum, iDb, 
+                    (char *)pKey, P4_KEYINFO);
+  sqlite3VdbeChangeP5(v, OPFLAG_BULKCSR|((memRootPage>=0)?OPFLAG_P2ISREG:0));
+
+  addr1 = sqlite3VdbeAddOp2(v, OP_SorterSort, iSorter, 0); VdbeCoverage(v);
+  if( IsUniqueIndex(pIndex) ){
+    int j2 = sqlite3VdbeCurrentAddr(v) + 3;
+    sqlite3VdbeGoto(v, j2);
+    addr2 = sqlite3VdbeCurrentAddr(v);
+    sqlite3VdbeAddOp4Int(v, OP_SorterCompare, iSorter, j2, regRecord,
+                         pIndex->nKeyCol); VdbeCoverage(v);
+    sqlite3UniqueConstraint(pParse, OE_Abort, pIndex);
+  }else{
+    addr2 = sqlite3VdbeCurrentAddr(v);
+  }
+  sqlite3VdbeAddOp3(v, OP_SorterData, iSorter, regRecord, iIdx);
+  sqlite3VdbeAddOp3(v, OP_Last, iIdx, 0, -1);
+  sqlite3VdbeAddOp3(v, OP_IdxInsert, iIdx, regRecord, 0);
+  sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
+  sqlite3ReleaseTempReg(pParse, regRecord);
+  sqlite3VdbeAddOp2(v, OP_SorterNext, iSorter, addr2); VdbeCoverage(v);
+  sqlite3VdbeJumpHere(v, addr1);
+
+  sqlite3VdbeAddOp1(v, OP_Close, iTab);
+  sqlite3VdbeAddOp1(v, OP_Close, iIdx);
+  sqlite3VdbeAddOp1(v, OP_Close, iSorter);
+}
+
+/*
+** Allocate heap space to hold an Index object with nCol columns.
+**
+** Increase the allocation size to provide an extra nExtra bytes
+** of 8-byte aligned space after the Index object and return a
+** pointer to this extra space in *ppExtra.
+*/
+SQLITE_PRIVATE Index *sqlite3AllocateIndexObject(
+  sqlite3 *db,         /* Database connection */
+  i16 nCol,            /* Total number of columns in the index */
+  int nExtra,          /* Number of bytes of extra space to alloc */
+  char **ppExtra       /* Pointer to the "extra" space */
+){
+  Index *p;            /* Allocated index object */
+  int nByte;           /* Bytes of space for Index object + arrays */
+
+  nByte = ROUND8(sizeof(Index)) +              /* Index structure  */
+          ROUND8(sizeof(char*)*nCol) +         /* Index.azColl     */
+          ROUND8(sizeof(LogEst)*(nCol+1) +     /* Index.aiRowLogEst   */
+                 sizeof(i16)*nCol +            /* Index.aiColumn   */
+                 sizeof(u8)*nCol);             /* Index.aSortOrder */
+  p = sqlite3DbMallocZero(db, nByte + nExtra);
+  if( p ){
+    char *pExtra = ((char*)p)+ROUND8(sizeof(Index));
+    p->azColl = (const char**)pExtra; pExtra += ROUND8(sizeof(char*)*nCol);
+    p->aiRowLogEst = (LogEst*)pExtra; pExtra += sizeof(LogEst)*(nCol+1);
+    p->aiColumn = (i16*)pExtra;       pExtra += sizeof(i16)*nCol;
+    p->aSortOrder = (u8*)pExtra;
+    p->nColumn = nCol;
+    p->nKeyCol = nCol - 1;
+    *ppExtra = ((char*)p) + nByte;
+  }
+  return p;
+}
+
+/*
+** Create a new index for an SQL table.  pName1.pName2 is the name of the index 
+** and pTblList is the name of the table that is to be indexed.  Both will 
+** be NULL for a primary key or an index that is created to satisfy a
+** UNIQUE constraint.  If pTable and pIndex are NULL, use pParse->pNewTable
+** as the table to be indexed.  pParse->pNewTable is a table that is
+** currently being constructed by a CREATE TABLE statement.
+**
+** pList is a list of columns to be indexed.  pList will be NULL if this
+** is a primary key or unique-constraint on the most recent column added
+** to the table currently under construction.  
+*/
+SQLITE_PRIVATE void sqlite3CreateIndex(
+  Parse *pParse,     /* All information about this parse */
+  Token *pName1,     /* First part of index name. May be NULL */
+  Token *pName2,     /* Second part of index name. May be NULL */
+  SrcList *pTblName, /* Table to index. Use pParse->pNewTable if 0 */
+  ExprList *pList,   /* A list of columns to be indexed */
+  int onError,       /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
+  Token *pStart,     /* The CREATE token that begins this statement */
+  Expr *pPIWhere,    /* WHERE clause for partial indices */
+  int sortOrder,     /* Sort order of primary key when pList==NULL */
+  int ifNotExist,    /* Omit error if index already exists */
+  u8 idxType         /* The index type */
+){
+  Table *pTab = 0;     /* Table to be indexed */
+  Index *pIndex = 0;   /* The index to be created */
+  char *zName = 0;     /* Name of the index */
+  int nName;           /* Number of characters in zName */
+  int i, j;
+  DbFixer sFix;        /* For assigning database names to pTable */
+  int sortOrderMask;   /* 1 to honor DESC in index.  0 to ignore. */
+  sqlite3 *db = pParse->db;
+  Db *pDb;             /* The specific table containing the indexed database */
+  int iDb;             /* Index of the database that is being written */
+  Token *pName = 0;    /* Unqualified name of the index to create */
+  struct ExprList_item *pListItem; /* For looping over pList */
+  int nExtra = 0;                  /* Space allocated for zExtra[] */
+  int nExtraCol;                   /* Number of extra columns needed */
+  char *zExtra = 0;                /* Extra space after the Index object */
+  Index *pPk = 0;      /* PRIMARY KEY index for WITHOUT ROWID tables */
+
+  if( db->mallocFailed || pParse->nErr>0 ){
+    goto exit_create_index;
+  }
+  if( IN_DECLARE_VTAB && idxType!=SQLITE_IDXTYPE_PRIMARYKEY ){
+    goto exit_create_index;
+  }
+  if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
+    goto exit_create_index;
+  }
+
+  /*
+  ** Find the table that is to be indexed.  Return early if not found.
+  */
+  if( pTblName!=0 ){
+
+    /* Use the two-part index name to determine the database 
+    ** to search for the table. 'Fix' the table name to this db
+    ** before looking up the table.
+    */
+    assert( pName1 && pName2 );
+    iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pName);
+    if( iDb<0 ) goto exit_create_index;
+    assert( pName && pName->z );
+
+#ifndef SQLITE_OMIT_TEMPDB
+    /* If the index name was unqualified, check if the table
+    ** is a temp table. If so, set the database to 1. Do not do this
+    ** if initialising a database schema.
+    */
+    if( !db->init.busy ){
+      pTab = sqlite3SrcListLookup(pParse, pTblName);
+      if( pName2->n==0 && pTab && pTab->pSchema==db->aDb[1].pSchema ){
+        iDb = 1;
+      }
+    }
+#endif
+
+    sqlite3FixInit(&sFix, pParse, iDb, "index", pName);
+    if( sqlite3FixSrcList(&sFix, pTblName) ){
+      /* Because the parser constructs pTblName from a single identifier,
+      ** sqlite3FixSrcList can never fail. */
+      assert(0);
+    }
+    pTab = sqlite3LocateTableItem(pParse, 0, &pTblName->a[0]);
+    assert( db->mallocFailed==0 || pTab==0 );
+    if( pTab==0 ) goto exit_create_index;
+    if( iDb==1 && db->aDb[iDb].pSchema!=pTab->pSchema ){
+      sqlite3ErrorMsg(pParse, 
+           "cannot create a TEMP index on non-TEMP table \"%s\"",
+           pTab->zName);
+      goto exit_create_index;
+    }
+    if( !HasRowid(pTab) ) pPk = sqlite3PrimaryKeyIndex(pTab);
+  }else{
+    assert( pName==0 );
+    assert( pStart==0 );
+    pTab = pParse->pNewTable;
+    if( !pTab ) goto exit_create_index;
+    iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+  }
+  pDb = &db->aDb[iDb];
+
+  assert( pTab!=0 );
+  assert( pParse->nErr==0 );
+  if( sqlite3StrNICmp(pTab->zName, "sqlite_", 7)==0 
+       && db->init.busy==0
+#if SQLITE_USER_AUTHENTICATION
+       && sqlite3UserAuthTable(pTab->zName)==0
+#endif
+       && sqlite3StrNICmp(&pTab->zName[7],"altertab_",9)!=0 ){
+    sqlite3ErrorMsg(pParse, "table %s may not be indexed", pTab->zName);
+    goto exit_create_index;
+  }
+#ifndef SQLITE_OMIT_VIEW
+  if( pTab->pSelect ){
+    sqlite3ErrorMsg(pParse, "views may not be indexed");
+    goto exit_create_index;
+  }
+#endif
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  if( IsVirtual(pTab) ){
+    sqlite3ErrorMsg(pParse, "virtual tables may not be indexed");
+    goto exit_create_index;
+  }
+#endif
+
+  /*
+  ** Find the name of the index.  Make sure there is not already another
+  ** index or table with the same name.  
+  **
+  ** Exception:  If we are reading the names of permanent indices from the
+  ** sqlite_master table (because some other process changed the schema) and
+  ** one of the index names collides with the name of a temporary table or
+  ** index, then we will continue to process this index.
+  **
+  ** If pName==0 it means that we are
+  ** dealing with a primary key or UNIQUE constraint.  We have to invent our
+  ** own name.
+  */
+  if( pName ){
+    zName = sqlite3NameFromToken(db, pName);
+    if( zName==0 ) goto exit_create_index;
+    assert( pName->z!=0 );
+    if( SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){
+      goto exit_create_index;
+    }
+    if( !db->init.busy ){
+      if( sqlite3FindTable(db, zName, 0)!=0 ){
+        sqlite3ErrorMsg(pParse, "there is already a table named %s", zName);
+        goto exit_create_index;
+      }
+    }
+    if( sqlite3FindIndex(db, zName, pDb->zDbSName)!=0 ){
+      if( !ifNotExist ){
+        sqlite3ErrorMsg(pParse, "index %s already exists", zName);
+      }else{
+        assert( !db->init.busy );
+        sqlite3CodeVerifySchema(pParse, iDb);
+      }
+      goto exit_create_index;
+    }
+  }else{
+    int n;
+    Index *pLoop;
+    for(pLoop=pTab->pIndex, n=1; pLoop; pLoop=pLoop->pNext, n++){}
+    zName = sqlite3MPrintf(db, "sqlite_autoindex_%s_%d", pTab->zName, n);
+    if( zName==0 ){
+      goto exit_create_index;
+    }
+
+    /* Automatic index names generated from within sqlite3_declare_vtab()
+    ** must have names that are distinct from normal automatic index names.
+    ** The following statement converts "sqlite3_autoindex..." into
+    ** "sqlite3_butoindex..." in order to make the names distinct.
+    ** The "vtab_err.test" test demonstrates the need of this statement. */
+    if( IN_DECLARE_VTAB ) zName[7]++;
+  }
+
+  /* Check for authorization to create an index.
+  */
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  {
+    const char *zDb = pDb->zDbSName;
+    if( sqlite3AuthCheck(pParse, SQLITE_INSERT, SCHEMA_TABLE(iDb), 0, zDb) ){
+      goto exit_create_index;
+    }
+    i = SQLITE_CREATE_INDEX;
+    if( !OMIT_TEMPDB && iDb==1 ) i = SQLITE_CREATE_TEMP_INDEX;
+    if( sqlite3AuthCheck(pParse, i, zName, pTab->zName, zDb) ){
+      goto exit_create_index;
+    }
+  }
+#endif
+
+  /* If pList==0, it means this routine was called to make a primary
+  ** key out of the last column added to the table under construction.
+  ** So create a fake list to simulate this.
+  */
+  if( pList==0 ){
+    Token prevCol;
+    sqlite3TokenInit(&prevCol, pTab->aCol[pTab->nCol-1].zName);
+    pList = sqlite3ExprListAppend(pParse, 0,
+              sqlite3ExprAlloc(db, TK_ID, &prevCol, 0));
+    if( pList==0 ) goto exit_create_index;
+    assert( pList->nExpr==1 );
+    sqlite3ExprListSetSortOrder(pList, sortOrder);
+  }else{
+    sqlite3ExprListCheckLength(pParse, pList, "index");
+  }
+
+  /* Figure out how many bytes of space are required to store explicitly
+  ** specified collation sequence names.
+  */
+  for(i=0; i<pList->nExpr; i++){
+    Expr *pExpr = pList->a[i].pExpr;
+    assert( pExpr!=0 );
+    if( pExpr->op==TK_COLLATE ){
+      nExtra += (1 + sqlite3Strlen30(pExpr->u.zToken));
+    }
+  }
+
+  /* 
+  ** Allocate the index structure. 
+  */
+  nName = sqlite3Strlen30(zName);
+  nExtraCol = pPk ? pPk->nKeyCol : 1;
+  pIndex = sqlite3AllocateIndexObject(db, pList->nExpr + nExtraCol,
+                                      nName + nExtra + 1, &zExtra);
+  if( db->mallocFailed ){
+    goto exit_create_index;
+  }
+  assert( EIGHT_BYTE_ALIGNMENT(pIndex->aiRowLogEst) );
+  assert( EIGHT_BYTE_ALIGNMENT(pIndex->azColl) );
+  pIndex->zName = zExtra;
+  zExtra += nName + 1;
+  memcpy(pIndex->zName, zName, nName+1);
+  pIndex->pTable = pTab;
+  pIndex->onError = (u8)onError;
+  pIndex->uniqNotNull = onError!=OE_None;
+  pIndex->idxType = idxType;
+  pIndex->pSchema = db->aDb[iDb].pSchema;
+  pIndex->nKeyCol = pList->nExpr;
+  if( pPIWhere ){
+    sqlite3ResolveSelfReference(pParse, pTab, NC_PartIdx, pPIWhere, 0);
+    pIndex->pPartIdxWhere = pPIWhere;
+    pPIWhere = 0;
+  }
+  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+
+  /* Check to see if we should honor DESC requests on index columns
+  */
+  if( pDb->pSchema->file_format>=4 ){
+    sortOrderMask = -1;   /* Honor DESC */
+  }else{
+    sortOrderMask = 0;    /* Ignore DESC */
+  }
+
+  /* Analyze the list of expressions that form the terms of the index and
+  ** report any errors.  In the common case where the expression is exactly
+  ** a table column, store that column in aiColumn[].  For general expressions,
+  ** populate pIndex->aColExpr and store XN_EXPR (-2) in aiColumn[].
+  **
+  ** TODO: Issue a warning if two or more columns of the index are identical.
+  ** TODO: Issue a warning if the table primary key is used as part of the
+  ** index key.
+  */
+  for(i=0, pListItem=pList->a; i<pList->nExpr; i++, pListItem++){
+    Expr *pCExpr;                  /* The i-th index expression */
+    int requestedSortOrder;        /* ASC or DESC on the i-th expression */
+    const char *zColl;             /* Collation sequence name */
+
+    sqlite3StringToId(pListItem->pExpr);
+    sqlite3ResolveSelfReference(pParse, pTab, NC_IdxExpr, pListItem->pExpr, 0);
+    if( pParse->nErr ) goto exit_create_index;
+    pCExpr = sqlite3ExprSkipCollate(pListItem->pExpr);
+    if( pCExpr->op!=TK_COLUMN ){
+      if( pTab==pParse->pNewTable ){
+        sqlite3ErrorMsg(pParse, "expressions prohibited in PRIMARY KEY and "
+                                "UNIQUE constraints");
+        goto exit_create_index;
+      }
+      if( pIndex->aColExpr==0 ){
+        ExprList *pCopy = sqlite3ExprListDup(db, pList, 0);
+        pIndex->aColExpr = pCopy;
+        if( !db->mallocFailed ){
+          assert( pCopy!=0 );
+          pListItem = &pCopy->a[i];
+        }
+      }
+      j = XN_EXPR;
+      pIndex->aiColumn[i] = XN_EXPR;
+      pIndex->uniqNotNull = 0;
+    }else{
+      j = pCExpr->iColumn;
+      assert( j<=0x7fff );
+      if( j<0 ){
+        j = pTab->iPKey;
+      }else if( pTab->aCol[j].notNull==0 ){
+        pIndex->uniqNotNull = 0;
+      }
+      pIndex->aiColumn[i] = (i16)j;
+    }
+    zColl = 0;
+    if( pListItem->pExpr->op==TK_COLLATE ){
+      int nColl;
+      zColl = pListItem->pExpr->u.zToken;
+      nColl = sqlite3Strlen30(zColl) + 1;
+      assert( nExtra>=nColl );
+      memcpy(zExtra, zColl, nColl);
+      zColl = zExtra;
+      zExtra += nColl;
+      nExtra -= nColl;
+    }else if( j>=0 ){
+      zColl = pTab->aCol[j].zColl;
+    }
+    if( !zColl ) zColl = sqlite3StrBINARY;
+    if( !db->init.busy && !sqlite3LocateCollSeq(pParse, zColl) ){
+      goto exit_create_index;
+    }
+    pIndex->azColl[i] = zColl;
+    requestedSortOrder = pListItem->sortOrder & sortOrderMask;
+    pIndex->aSortOrder[i] = (u8)requestedSortOrder;
+  }
+
+  /* Append the table key to the end of the index.  For WITHOUT ROWID
+  ** tables (when pPk!=0) this will be the declared PRIMARY KEY.  For
+  ** normal tables (when pPk==0) this will be the rowid.
+  */
+  if( pPk ){
+    for(j=0; j<pPk->nKeyCol; j++){
+      int x = pPk->aiColumn[j];
+      assert( x>=0 );
+      if( hasColumn(pIndex->aiColumn, pIndex->nKeyCol, x) ){
+        pIndex->nColumn--; 
+      }else{
+        pIndex->aiColumn[i] = x;
+        pIndex->azColl[i] = pPk->azColl[j];
+        pIndex->aSortOrder[i] = pPk->aSortOrder[j];
+        i++;
+      }
+    }
+    assert( i==pIndex->nColumn );
+  }else{
+    pIndex->aiColumn[i] = XN_ROWID;
+    pIndex->azColl[i] = sqlite3StrBINARY;
+  }
+  sqlite3DefaultRowEst(pIndex);
+  if( pParse->pNewTable==0 ) estimateIndexWidth(pIndex);
+
+  /* If this index contains every column of its table, then mark
+  ** it as a covering index */
+  assert( HasRowid(pTab) 
+      || pTab->iPKey<0 || sqlite3ColumnOfIndex(pIndex, pTab->iPKey)>=0 );
+  if( pTblName!=0 && pIndex->nColumn>=pTab->nCol ){
+    pIndex->isCovering = 1;
+    for(j=0; j<pTab->nCol; j++){
+      if( j==pTab->iPKey ) continue;
+      if( sqlite3ColumnOfIndex(pIndex,j)>=0 ) continue;
+      pIndex->isCovering = 0;
+      break;
+    }
+  }
+
+  if( pTab==pParse->pNewTable ){
+    /* This routine has been called to create an automatic index as a
+    ** result of a PRIMARY KEY or UNIQUE clause on a column definition, or
+    ** a PRIMARY KEY or UNIQUE clause following the column definitions.
+    ** i.e. one of:
+    **
+    ** CREATE TABLE t(x PRIMARY KEY, y);
+    ** CREATE TABLE t(x, y, UNIQUE(x, y));
+    **
+    ** Either way, check to see if the table already has such an index. If
+    ** so, don't bother creating this one. This only applies to
+    ** automatically created indices. Users can do as they wish with
+    ** explicit indices.
+    **
+    ** Two UNIQUE or PRIMARY KEY constraints are considered equivalent
+    ** (and thus suppressing the second one) even if they have different
+    ** sort orders.
+    **
+    ** If there are different collating sequences or if the columns of
+    ** the constraint occur in different orders, then the constraints are
+    ** considered distinct and both result in separate indices.
+    */
+    Index *pIdx;
+    for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+      int k;
+      assert( IsUniqueIndex(pIdx) );
+      assert( pIdx->idxType!=SQLITE_IDXTYPE_APPDEF );
+      assert( IsUniqueIndex(pIndex) );
+
+      if( pIdx->nKeyCol!=pIndex->nKeyCol ) continue;
+      for(k=0; k<pIdx->nKeyCol; k++){
+        const char *z1;
+        const char *z2;
+        assert( pIdx->aiColumn[k]>=0 );
+        if( pIdx->aiColumn[k]!=pIndex->aiColumn[k] ) break;
+        z1 = pIdx->azColl[k];
+        z2 = pIndex->azColl[k];
+        if( sqlite3StrICmp(z1, z2) ) break;
+      }
+      if( k==pIdx->nKeyCol ){
+        if( pIdx->onError!=pIndex->onError ){
+          /* This constraint creates the same index as a previous
+          ** constraint specified somewhere in the CREATE TABLE statement.
+          ** However the ON CONFLICT clauses are different. If both this 
+          ** constraint and the previous equivalent constraint have explicit
+          ** ON CONFLICT clauses this is an error. Otherwise, use the
+          ** explicitly specified behavior for the index.
+          */
+          if( !(pIdx->onError==OE_Default || pIndex->onError==OE_Default) ){
+            sqlite3ErrorMsg(pParse, 
+                "conflicting ON CONFLICT clauses specified", 0);
+          }
+          if( pIdx->onError==OE_Default ){
+            pIdx->onError = pIndex->onError;
+          }
+        }
+        if( idxType==SQLITE_IDXTYPE_PRIMARYKEY ) pIdx->idxType = idxType;
+        goto exit_create_index;
+      }
+    }
+  }
+
+  /* Link the new Index structure to its table and to the other
+  ** in-memory database structures. 
+  */
+  assert( pParse->nErr==0 );
+  if( db->init.busy ){
+    Index *p;
+    assert( !IN_DECLARE_VTAB );
+    assert( sqlite3SchemaMutexHeld(db, 0, pIndex->pSchema) );
+    p = sqlite3HashInsert(&pIndex->pSchema->idxHash, 
+                          pIndex->zName, pIndex);
+    if( p ){
+      assert( p==pIndex );  /* Malloc must have failed */
+      sqlite3OomFault(db);
+      goto exit_create_index;
+    }
+    db->flags |= SQLITE_InternChanges;
+    if( pTblName!=0 ){
+      pIndex->tnum = db->init.newTnum;
+    }
+  }
+
+  /* If this is the initial CREATE INDEX statement (or CREATE TABLE if the
+  ** index is an implied index for a UNIQUE or PRIMARY KEY constraint) then
+  ** emit code to allocate the index rootpage on disk and make an entry for
+  ** the index in the sqlite_master table and populate the index with
+  ** content.  But, do not do this if we are simply reading the sqlite_master
+  ** table to parse the schema, or if this index is the PRIMARY KEY index
+  ** of a WITHOUT ROWID table.
+  **
+  ** If pTblName==0 it means this index is generated as an implied PRIMARY KEY
+  ** or UNIQUE index in a CREATE TABLE statement.  Since the table
+  ** has just been created, it contains no data and the index initialization
+  ** step can be skipped.
+  */
+  else if( HasRowid(pTab) || pTblName!=0 ){
+    Vdbe *v;
+    char *zStmt;
+    int iMem = ++pParse->nMem;
+
+    v = sqlite3GetVdbe(pParse);
+    if( v==0 ) goto exit_create_index;
+
+    sqlite3BeginWriteOperation(pParse, 1, iDb);
+
+    /* Create the rootpage for the index using CreateIndex. But before
+    ** doing so, code a Noop instruction and store its address in 
+    ** Index.tnum. This is required in case this index is actually a 
+    ** PRIMARY KEY and the table is actually a WITHOUT ROWID table. In 
+    ** that case the convertToWithoutRowidTable() routine will replace
+    ** the Noop with a Goto to jump over the VDBE code generated below. */
+    pIndex->tnum = sqlite3VdbeAddOp0(v, OP_Noop);
+    sqlite3VdbeAddOp2(v, OP_CreateIndex, iDb, iMem);
+
+    /* Gather the complete text of the CREATE INDEX statement into
+    ** the zStmt variable
+    */
+    if( pStart ){
+      int n = (int)(pParse->sLastToken.z - pName->z) + pParse->sLastToken.n;
+      if( pName->z[n-1]==';' ) n--;
+      /* A named index with an explicit CREATE INDEX statement */
+      zStmt = sqlite3MPrintf(db, "CREATE%s INDEX %.*s",
+        onError==OE_None ? "" : " UNIQUE", n, pName->z);
+    }else{
+      /* An automatic index created by a PRIMARY KEY or UNIQUE constraint */
+      /* zStmt = sqlite3MPrintf(""); */
+      zStmt = 0;
+    }
+
+    /* Add an entry in sqlite_master for this index
+    */
+    sqlite3NestedParse(pParse, 
+        "INSERT INTO %Q.%s VALUES('index',%Q,%Q,#%d,%Q);",
+        db->aDb[iDb].zDbSName, SCHEMA_TABLE(iDb),
+        pIndex->zName,
+        pTab->zName,
+        iMem,
+        zStmt
+    );
+    sqlite3DbFree(db, zStmt);
+
+    /* Fill the index with data and reparse the schema. Code an OP_Expire
+    ** to invalidate all pre-compiled statements.
+    */
+    if( pTblName ){
+      sqlite3RefillIndex(pParse, pIndex, iMem);
+      sqlite3ChangeCookie(pParse, iDb);
+      sqlite3VdbeAddParseSchemaOp(v, iDb,
+         sqlite3MPrintf(db, "name='%q' AND type='index'", pIndex->zName));
+      sqlite3VdbeAddOp0(v, OP_Expire);
+    }
+
+    sqlite3VdbeJumpHere(v, pIndex->tnum);
+  }
+
+  /* When adding an index to the list of indices for a table, make
+  ** sure all indices labeled OE_Replace come after all those labeled
+  ** OE_Ignore.  This is necessary for the correct constraint check
+  ** processing (in sqlite3GenerateConstraintChecks()) as part of
+  ** UPDATE and INSERT statements.  
+  */
+  if( db->init.busy || pTblName==0 ){
+    if( onError!=OE_Replace || pTab->pIndex==0
+         || pTab->pIndex->onError==OE_Replace){
+      pIndex->pNext = pTab->pIndex;
+      pTab->pIndex = pIndex;
+    }else{
+      Index *pOther = pTab->pIndex;
+      while( pOther->pNext && pOther->pNext->onError!=OE_Replace ){
+        pOther = pOther->pNext;
+      }
+      pIndex->pNext = pOther->pNext;
+      pOther->pNext = pIndex;
+    }
+    pIndex = 0;
+  }
+
+  /* Clean up before exiting */
+exit_create_index:
+  if( pIndex ) freeIndex(db, pIndex);
+  sqlite3ExprDelete(db, pPIWhere);
+  sqlite3ExprListDelete(db, pList);
+  sqlite3SrcListDelete(db, pTblName);
+  sqlite3DbFree(db, zName);
+}
+
+/*
+** Fill the Index.aiRowEst[] array with default information - information
+** to be used when we have not run the ANALYZE command.
+**
+** aiRowEst[0] is supposed to contain the number of elements in the index.
+** Since we do not know, guess 1 million.  aiRowEst[1] is an estimate of the
+** number of rows in the table that match any particular value of the
+** first column of the index.  aiRowEst[2] is an estimate of the number
+** of rows that match any particular combination of the first 2 columns
+** of the index.  And so forth.  It must always be the case that
+*
+**           aiRowEst[N]<=aiRowEst[N-1]
+**           aiRowEst[N]>=1
+**
+** Apart from that, we have little to go on besides intuition as to
+** how aiRowEst[] should be initialized.  The numbers generated here
+** are based on typical values found in actual indices.
+*/
+SQLITE_PRIVATE void sqlite3DefaultRowEst(Index *pIdx){
+  /*                10,  9,  8,  7,  6 */
+  LogEst aVal[] = { 33, 32, 30, 28, 26 };
+  LogEst *a = pIdx->aiRowLogEst;
+  int nCopy = MIN(ArraySize(aVal), pIdx->nKeyCol);
+  int i;
+
+  /* Set the first entry (number of rows in the index) to the estimated 
+  ** number of rows in the table, or half the number of rows in the table
+  ** for a partial index.   But do not let the estimate drop below 10. */
+  a[0] = pIdx->pTable->nRowLogEst;
+  if( pIdx->pPartIdxWhere!=0 ) a[0] -= 10;  assert( 10==sqlite3LogEst(2) );
+  if( a[0]<33 ) a[0] = 33;                  assert( 33==sqlite3LogEst(10) );
+
+  /* Estimate that a[1] is 10, a[2] is 9, a[3] is 8, a[4] is 7, a[5] is
+  ** 6 and each subsequent value (if any) is 5.  */
+  memcpy(&a[1], aVal, nCopy*sizeof(LogEst));
+  for(i=nCopy+1; i<=pIdx->nKeyCol; i++){
+    a[i] = 23;                    assert( 23==sqlite3LogEst(5) );
+  }
+
+  assert( 0==sqlite3LogEst(1) );
+  if( IsUniqueIndex(pIdx) ) a[pIdx->nKeyCol] = 0;
+}
+
+/*
+** This routine will drop an existing named index.  This routine
+** implements the DROP INDEX statement.
+*/
+SQLITE_PRIVATE void sqlite3DropIndex(Parse *pParse, SrcList *pName, int ifExists){
+  Index *pIndex;
+  Vdbe *v;
+  sqlite3 *db = pParse->db;
+  int iDb;
+
+  assert( pParse->nErr==0 );   /* Never called with prior errors */
+  if( db->mallocFailed ){
+    goto exit_drop_index;
+  }
+  assert( pName->nSrc==1 );
+  if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
+    goto exit_drop_index;
+  }
+  pIndex = sqlite3FindIndex(db, pName->a[0].zName, pName->a[0].zDatabase);
+  if( pIndex==0 ){
+    if( !ifExists ){
+      sqlite3ErrorMsg(pParse, "no such index: %S", pName, 0);
+    }else{
+      sqlite3CodeVerifyNamedSchema(pParse, pName->a[0].zDatabase);
+    }
+    pParse->checkSchema = 1;
+    goto exit_drop_index;
+  }
+  if( pIndex->idxType!=SQLITE_IDXTYPE_APPDEF ){
+    sqlite3ErrorMsg(pParse, "index associated with UNIQUE "
+      "or PRIMARY KEY constraint cannot be dropped", 0);
+    goto exit_drop_index;
+  }
+  iDb = sqlite3SchemaToIndex(db, pIndex->pSchema);
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  {
+    int code = SQLITE_DROP_INDEX;
+    Table *pTab = pIndex->pTable;
+    const char *zDb = db->aDb[iDb].zDbSName;
+    const char *zTab = SCHEMA_TABLE(iDb);
+    if( sqlite3AuthCheck(pParse, SQLITE_DELETE, zTab, 0, zDb) ){
+      goto exit_drop_index;
+    }
+    if( !OMIT_TEMPDB && iDb ) code = SQLITE_DROP_TEMP_INDEX;
+    if( sqlite3AuthCheck(pParse, code, pIndex->zName, pTab->zName, zDb) ){
+      goto exit_drop_index;
+    }
+  }
+#endif
+
+  /* Generate code to remove the index and from the master table */
+  v = sqlite3GetVdbe(pParse);
+  if( v ){
+    sqlite3BeginWriteOperation(pParse, 1, iDb);
+    sqlite3NestedParse(pParse,
+       "DELETE FROM %Q.%s WHERE name=%Q AND type='index'",
+       db->aDb[iDb].zDbSName, SCHEMA_TABLE(iDb), pIndex->zName
+    );
+    sqlite3ClearStatTables(pParse, iDb, "idx", pIndex->zName);
+    sqlite3ChangeCookie(pParse, iDb);
+    destroyRootPage(pParse, pIndex->tnum, iDb);
+    sqlite3VdbeAddOp4(v, OP_DropIndex, iDb, 0, 0, pIndex->zName, 0);
+  }
+
+exit_drop_index:
+  sqlite3SrcListDelete(db, pName);
+}
+
+/*
+** pArray is a pointer to an array of objects. Each object in the
+** array is szEntry bytes in size. This routine uses sqlite3DbRealloc()
+** to extend the array so that there is space for a new object at the end.
+**
+** When this function is called, *pnEntry contains the current size of
+** the array (in entries - so the allocation is ((*pnEntry) * szEntry) bytes
+** in total).
+**
+** If the realloc() is successful (i.e. if no OOM condition occurs), the
+** space allocated for the new object is zeroed, *pnEntry updated to
+** reflect the new size of the array and a pointer to the new allocation
+** returned. *pIdx is set to the index of the new array entry in this case.
+**
+** Otherwise, if the realloc() fails, *pIdx is set to -1, *pnEntry remains
+** unchanged and a copy of pArray returned.
+*/
+SQLITE_PRIVATE void *sqlite3ArrayAllocate(
+  sqlite3 *db,      /* Connection to notify of malloc failures */
+  void *pArray,     /* Array of objects.  Might be reallocated */
+  int szEntry,      /* Size of each object in the array */
+  int *pnEntry,     /* Number of objects currently in use */
+  int *pIdx         /* Write the index of a new slot here */
+){
+  char *z;
+  int n = *pnEntry;
+  if( (n & (n-1))==0 ){
+    int sz = (n==0) ? 1 : 2*n;
+    void *pNew = sqlite3DbRealloc(db, pArray, sz*szEntry);
+    if( pNew==0 ){
+      *pIdx = -1;
+      return pArray;
+    }
+    pArray = pNew;
+  }
+  z = (char*)pArray;
+  memset(&z[n * szEntry], 0, szEntry);
+  *pIdx = n;
+  ++*pnEntry;
+  return pArray;
+}
+
+/*
+** Append a new element to the given IdList.  Create a new IdList if
+** need be.
+**
+** A new IdList is returned, or NULL if malloc() fails.
+*/
+SQLITE_PRIVATE IdList *sqlite3IdListAppend(sqlite3 *db, IdList *pList, Token *pToken){
+  int i;
+  if( pList==0 ){
+    pList = sqlite3DbMallocZero(db, sizeof(IdList) );
+    if( pList==0 ) return 0;
+  }
+  pList->a = sqlite3ArrayAllocate(
+      db,
+      pList->a,
+      sizeof(pList->a[0]),
+      &pList->nId,
+      &i
+  );
+  if( i<0 ){
+    sqlite3IdListDelete(db, pList);
+    return 0;
+  }
+  pList->a[i].zName = sqlite3NameFromToken(db, pToken);
+  return pList;
+}
+
+/*
+** Delete an IdList.
+*/
+SQLITE_PRIVATE void sqlite3IdListDelete(sqlite3 *db, IdList *pList){
+  int i;
+  if( pList==0 ) return;
+  for(i=0; i<pList->nId; i++){
+    sqlite3DbFree(db, pList->a[i].zName);
+  }
+  sqlite3DbFree(db, pList->a);
+  sqlite3DbFree(db, pList);
+}
+
+/*
+** Return the index in pList of the identifier named zId.  Return -1
+** if not found.
+*/
+SQLITE_PRIVATE int sqlite3IdListIndex(IdList *pList, const char *zName){
+  int i;
+  if( pList==0 ) return -1;
+  for(i=0; i<pList->nId; i++){
+    if( sqlite3StrICmp(pList->a[i].zName, zName)==0 ) return i;
+  }
+  return -1;
+}
+
+/*
+** Expand the space allocated for the given SrcList object by
+** creating nExtra new slots beginning at iStart.  iStart is zero based.
+** New slots are zeroed.
+**
+** For example, suppose a SrcList initially contains two entries: A,B.
+** To append 3 new entries onto the end, do this:
+**
+**    sqlite3SrcListEnlarge(db, pSrclist, 3, 2);
+**
+** After the call above it would contain:  A, B, nil, nil, nil.
+** If the iStart argument had been 1 instead of 2, then the result
+** would have been:  A, nil, nil, nil, B.  To prepend the new slots,
+** the iStart value would be 0.  The result then would
+** be: nil, nil, nil, A, B.
+**
+** If a memory allocation fails the SrcList is unchanged.  The
+** db->mallocFailed flag will be set to true.
+*/
+SQLITE_PRIVATE SrcList *sqlite3SrcListEnlarge(
+  sqlite3 *db,       /* Database connection to notify of OOM errors */
+  SrcList *pSrc,     /* The SrcList to be enlarged */
+  int nExtra,        /* Number of new slots to add to pSrc->a[] */
+  int iStart         /* Index in pSrc->a[] of first new slot */
+){
+  int i;
+
+  /* Sanity checking on calling parameters */
+  assert( iStart>=0 );
+  assert( nExtra>=1 );
+  assert( pSrc!=0 );
+  assert( iStart<=pSrc->nSrc );
+
+  /* Allocate additional space if needed */
+  if( (u32)pSrc->nSrc+nExtra>pSrc->nAlloc ){
+    SrcList *pNew;
+    int nAlloc = pSrc->nSrc+nExtra;
+    int nGot;
+    pNew = sqlite3DbRealloc(db, pSrc,
+               sizeof(*pSrc) + (nAlloc-1)*sizeof(pSrc->a[0]) );
+    if( pNew==0 ){
+      assert( db->mallocFailed );
+      return pSrc;
+    }
+    pSrc = pNew;
+    nGot = (sqlite3DbMallocSize(db, pNew) - sizeof(*pSrc))/sizeof(pSrc->a[0])+1;
+    pSrc->nAlloc = nGot;
+  }
+
+  /* Move existing slots that come after the newly inserted slots
+  ** out of the way */
+  for(i=pSrc->nSrc-1; i>=iStart; i--){
+    pSrc->a[i+nExtra] = pSrc->a[i];
+  }
+  pSrc->nSrc += nExtra;
+
+  /* Zero the newly allocated slots */
+  memset(&pSrc->a[iStart], 0, sizeof(pSrc->a[0])*nExtra);
+  for(i=iStart; i<iStart+nExtra; i++){
+    pSrc->a[i].iCursor = -1;
+  }
+
+  /* Return a pointer to the enlarged SrcList */
+  return pSrc;
+}
+
+
+/*
+** Append a new table name to the given SrcList.  Create a new SrcList if
+** need be.  A new entry is created in the SrcList even if pTable is NULL.
+**
+** A SrcList is returned, or NULL if there is an OOM error.  The returned
+** SrcList might be the same as the SrcList that was input or it might be
+** a new one.  If an OOM error does occurs, then the prior value of pList
+** that is input to this routine is automatically freed.
+**
+** If pDatabase is not null, it means that the table has an optional
+** database name prefix.  Like this:  "database.table".  The pDatabase
+** points to the table name and the pTable points to the database name.
+** The SrcList.a[].zName field is filled with the table name which might
+** come from pTable (if pDatabase is NULL) or from pDatabase.  
+** SrcList.a[].zDatabase is filled with the database name from pTable,
+** or with NULL if no database is specified.
+**
+** In other words, if call like this:
+**
+**         sqlite3SrcListAppend(D,A,B,0);
+**
+** Then B is a table name and the database name is unspecified.  If called
+** like this:
+**
+**         sqlite3SrcListAppend(D,A,B,C);
+**
+** Then C is the table name and B is the database name.  If C is defined
+** then so is B.  In other words, we never have a case where:
+**
+**         sqlite3SrcListAppend(D,A,0,C);
+**
+** Both pTable and pDatabase are assumed to be quoted.  They are dequoted
+** before being added to the SrcList.
+*/
+SQLITE_PRIVATE SrcList *sqlite3SrcListAppend(
+  sqlite3 *db,        /* Connection to notify of malloc failures */
+  SrcList *pList,     /* Append to this SrcList. NULL creates a new SrcList */
+  Token *pTable,      /* Table to append */
+  Token *pDatabase    /* Database of the table */
+){
+  struct SrcList_item *pItem;
+  assert( pDatabase==0 || pTable!=0 );  /* Cannot have C without B */
+  assert( db!=0 );
+  if( pList==0 ){
+    pList = sqlite3DbMallocRawNN(db, sizeof(SrcList) );
+    if( pList==0 ) return 0;
+    pList->nAlloc = 1;
+    pList->nSrc = 0;
+  }
+  pList = sqlite3SrcListEnlarge(db, pList, 1, pList->nSrc);
+  if( db->mallocFailed ){
+    sqlite3SrcListDelete(db, pList);
+    return 0;
+  }
+  pItem = &pList->a[pList->nSrc-1];
+  if( pDatabase && pDatabase->z==0 ){
+    pDatabase = 0;
+  }
+  if( pDatabase ){
+    Token *pTemp = pDatabase;
+    pDatabase = pTable;
+    pTable = pTemp;
+  }
+  pItem->zName = sqlite3NameFromToken(db, pTable);
+  pItem->zDatabase = sqlite3NameFromToken(db, pDatabase);
+  return pList;
+}
+
+/*
+** Assign VdbeCursor index numbers to all tables in a SrcList
+*/
+SQLITE_PRIVATE void sqlite3SrcListAssignCursors(Parse *pParse, SrcList *pList){
+  int i;
+  struct SrcList_item *pItem;
+  assert(pList || pParse->db->mallocFailed );
+  if( pList ){
+    for(i=0, pItem=pList->a; i<pList->nSrc; i++, pItem++){
+      if( pItem->iCursor>=0 ) break;
+      pItem->iCursor = pParse->nTab++;
+      if( pItem->pSelect ){
+        sqlite3SrcListAssignCursors(pParse, pItem->pSelect->pSrc);
+      }
+    }
+  }
+}
+
+/*
+** Delete an entire SrcList including all its substructure.
+*/
+SQLITE_PRIVATE void sqlite3SrcListDelete(sqlite3 *db, SrcList *pList){
+  int i;
+  struct SrcList_item *pItem;
+  if( pList==0 ) return;
+  for(pItem=pList->a, i=0; i<pList->nSrc; i++, pItem++){
+    sqlite3DbFree(db, pItem->zDatabase);
+    sqlite3DbFree(db, pItem->zName);
+    sqlite3DbFree(db, pItem->zAlias);
+    if( pItem->fg.isIndexedBy ) sqlite3DbFree(db, pItem->u1.zIndexedBy);
+    if( pItem->fg.isTabFunc ) sqlite3ExprListDelete(db, pItem->u1.pFuncArg);
+    sqlite3DeleteTable(db, pItem->pTab);
+    sqlite3SelectDelete(db, pItem->pSelect);
+    sqlite3ExprDelete(db, pItem->pOn);
+    sqlite3IdListDelete(db, pItem->pUsing);
+  }
+  sqlite3DbFree(db, pList);
+}
+
+/*
+** This routine is called by the parser to add a new term to the
+** end of a growing FROM clause.  The "p" parameter is the part of
+** the FROM clause that has already been constructed.  "p" is NULL
+** if this is the first term of the FROM clause.  pTable and pDatabase
+** are the name of the table and database named in the FROM clause term.
+** pDatabase is NULL if the database name qualifier is missing - the
+** usual case.  If the term has an alias, then pAlias points to the
+** alias token.  If the term is a subquery, then pSubquery is the
+** SELECT statement that the subquery encodes.  The pTable and
+** pDatabase parameters are NULL for subqueries.  The pOn and pUsing
+** parameters are the content of the ON and USING clauses.
+**
+** Return a new SrcList which encodes is the FROM with the new
+** term added.
+*/
+SQLITE_PRIVATE SrcList *sqlite3SrcListAppendFromTerm(
+  Parse *pParse,          /* Parsing context */
+  SrcList *p,             /* The left part of the FROM clause already seen */
+  Token *pTable,          /* Name of the table to add to the FROM clause */
+  Token *pDatabase,       /* Name of the database containing pTable */
+  Token *pAlias,          /* The right-hand side of the AS subexpression */
+  Select *pSubquery,      /* A subquery used in place of a table name */
+  Expr *pOn,              /* The ON clause of a join */
+  IdList *pUsing          /* The USING clause of a join */
+){
+  struct SrcList_item *pItem;
+  sqlite3 *db = pParse->db;
+  if( !p && (pOn || pUsing) ){
+    sqlite3ErrorMsg(pParse, "a JOIN clause is required before %s", 
+      (pOn ? "ON" : "USING")
+    );
+    goto append_from_error;
+  }
+  p = sqlite3SrcListAppend(db, p, pTable, pDatabase);
+  if( p==0 || NEVER(p->nSrc==0) ){
+    goto append_from_error;
+  }
+  pItem = &p->a[p->nSrc-1];
+  assert( pAlias!=0 );
+  if( pAlias->n ){
+    pItem->zAlias = sqlite3NameFromToken(db, pAlias);
+  }
+  pItem->pSelect = pSubquery;
+  pItem->pOn = pOn;
+  pItem->pUsing = pUsing;
+  return p;
+
+ append_from_error:
+  assert( p==0 );
+  sqlite3ExprDelete(db, pOn);
+  sqlite3IdListDelete(db, pUsing);
+  sqlite3SelectDelete(db, pSubquery);
+  return 0;
+}
+
+/*
+** Add an INDEXED BY or NOT INDEXED clause to the most recently added 
+** element of the source-list passed as the second argument.
+*/
+SQLITE_PRIVATE void sqlite3SrcListIndexedBy(Parse *pParse, SrcList *p, Token *pIndexedBy){
+  assert( pIndexedBy!=0 );
+  if( p && ALWAYS(p->nSrc>0) ){
+    struct SrcList_item *pItem = &p->a[p->nSrc-1];
+    assert( pItem->fg.notIndexed==0 );
+    assert( pItem->fg.isIndexedBy==0 );
+    assert( pItem->fg.isTabFunc==0 );
+    if( pIndexedBy->n==1 && !pIndexedBy->z ){
+      /* A "NOT INDEXED" clause was supplied. See parse.y 
+      ** construct "indexed_opt" for details. */
+      pItem->fg.notIndexed = 1;
+    }else{
+      pItem->u1.zIndexedBy = sqlite3NameFromToken(pParse->db, pIndexedBy);
+      pItem->fg.isIndexedBy = (pItem->u1.zIndexedBy!=0);
+    }
+  }
+}
+
+/*
+** Add the list of function arguments to the SrcList entry for a
+** table-valued-function.
+*/
+SQLITE_PRIVATE void sqlite3SrcListFuncArgs(Parse *pParse, SrcList *p, ExprList *pList){
+  if( p ){
+    struct SrcList_item *pItem = &p->a[p->nSrc-1];
+    assert( pItem->fg.notIndexed==0 );
+    assert( pItem->fg.isIndexedBy==0 );
+    assert( pItem->fg.isTabFunc==0 );
+    pItem->u1.pFuncArg = pList;
+    pItem->fg.isTabFunc = 1;
+  }else{
+    sqlite3ExprListDelete(pParse->db, pList);
+  }
+}
+
+/*
+** When building up a FROM clause in the parser, the join operator
+** is initially attached to the left operand.  But the code generator
+** expects the join operator to be on the right operand.  This routine
+** Shifts all join operators from left to right for an entire FROM
+** clause.
+**
+** Example: Suppose the join is like this:
+**
+**           A natural cross join B
+**
+** The operator is "natural cross join".  The A and B operands are stored
+** in p->a[0] and p->a[1], respectively.  The parser initially stores the
+** operator with A.  This routine shifts that operator over to B.
+*/
+SQLITE_PRIVATE void sqlite3SrcListShiftJoinType(SrcList *p){
+  if( p ){
+    int i;
+    for(i=p->nSrc-1; i>0; i--){
+      p->a[i].fg.jointype = p->a[i-1].fg.jointype;
+    }
+    p->a[0].fg.jointype = 0;
+  }
+}
+
+/*
+** Generate VDBE code for a BEGIN statement.
+*/
+SQLITE_PRIVATE void sqlite3BeginTransaction(Parse *pParse, int type){
+  sqlite3 *db;
+  Vdbe *v;
+  int i;
+
+  assert( pParse!=0 );
+  db = pParse->db;
+  assert( db!=0 );
+  if( sqlite3AuthCheck(pParse, SQLITE_TRANSACTION, "BEGIN", 0, 0) ){
+    return;
+  }
+  v = sqlite3GetVdbe(pParse);
+  if( !v ) return;
+  if( type!=TK_DEFERRED ){
+    for(i=0; i<db->nDb; i++){
+      sqlite3VdbeAddOp2(v, OP_Transaction, i, (type==TK_EXCLUSIVE)+1);
+      sqlite3VdbeUsesBtree(v, i);
+    }
+  }
+  sqlite3VdbeAddOp0(v, OP_AutoCommit);
+}
+
+/*
+** Generate VDBE code for a COMMIT statement.
+*/
+SQLITE_PRIVATE void sqlite3CommitTransaction(Parse *pParse){
+  Vdbe *v;
+
+  assert( pParse!=0 );
+  assert( pParse->db!=0 );
+  if( sqlite3AuthCheck(pParse, SQLITE_TRANSACTION, "COMMIT", 0, 0) ){
+    return;
+  }
+  v = sqlite3GetVdbe(pParse);
+  if( v ){
+    sqlite3VdbeAddOp1(v, OP_AutoCommit, 1);
+  }
+}
+
+/*
+** Generate VDBE code for a ROLLBACK statement.
+*/
+SQLITE_PRIVATE void sqlite3RollbackTransaction(Parse *pParse){
+  Vdbe *v;
+
+  assert( pParse!=0 );
+  assert( pParse->db!=0 );
+  if( sqlite3AuthCheck(pParse, SQLITE_TRANSACTION, "ROLLBACK", 0, 0) ){
+    return;
+  }
+  v = sqlite3GetVdbe(pParse);
+  if( v ){
+    sqlite3VdbeAddOp2(v, OP_AutoCommit, 1, 1);
+  }
+}
+
+/*
+** This function is called by the parser when it parses a command to create,
+** release or rollback an SQL savepoint. 
+*/
+SQLITE_PRIVATE void sqlite3Savepoint(Parse *pParse, int op, Token *pName){
+  char *zName = sqlite3NameFromToken(pParse->db, pName);
+  if( zName ){
+    Vdbe *v = sqlite3GetVdbe(pParse);
+#ifndef SQLITE_OMIT_AUTHORIZATION
+    static const char * const az[] = { "BEGIN", "RELEASE", "ROLLBACK" };
+    assert( !SAVEPOINT_BEGIN && SAVEPOINT_RELEASE==1 && SAVEPOINT_ROLLBACK==2 );
+#endif
+    if( !v || sqlite3AuthCheck(pParse, SQLITE_SAVEPOINT, az[op], zName, 0) ){
+      sqlite3DbFree(pParse->db, zName);
+      return;
+    }
+    sqlite3VdbeAddOp4(v, OP_Savepoint, op, 0, 0, zName, P4_DYNAMIC);
+  }
+}
+
+/*
+** Make sure the TEMP database is open and available for use.  Return
+** the number of errors.  Leave any error messages in the pParse structure.
+*/
+SQLITE_PRIVATE int sqlite3OpenTempDatabase(Parse *pParse){
+  sqlite3 *db = pParse->db;
+  if( db->aDb[1].pBt==0 && !pParse->explain ){
+    int rc;
+    Btree *pBt;
+    static const int flags = 
+          SQLITE_OPEN_READWRITE |
+          SQLITE_OPEN_CREATE |
+          SQLITE_OPEN_EXCLUSIVE |
+          SQLITE_OPEN_DELETEONCLOSE |
+          SQLITE_OPEN_TEMP_DB;
+
+    rc = sqlite3BtreeOpen(db->pVfs, 0, db, &pBt, 0, flags);
+    if( rc!=SQLITE_OK ){
+      sqlite3ErrorMsg(pParse, "unable to open a temporary database "
+        "file for storing temporary tables");
+      pParse->rc = rc;
+      return 1;
+    }
+    db->aDb[1].pBt = pBt;
+    assert( db->aDb[1].pSchema );
+    if( SQLITE_NOMEM==sqlite3BtreeSetPageSize(pBt, db->nextPagesize, -1, 0) ){
+      sqlite3OomFault(db);
+      return 1;
+    }
+  }
+  return 0;
+}
+
+/*
+** Record the fact that the schema cookie will need to be verified
+** for database iDb.  The code to actually verify the schema cookie
+** will occur at the end of the top-level VDBE and will be generated
+** later, by sqlite3FinishCoding().
+*/
+SQLITE_PRIVATE void sqlite3CodeVerifySchema(Parse *pParse, int iDb){
+  Parse *pToplevel = sqlite3ParseToplevel(pParse);
+
+  assert( iDb>=0 && iDb<pParse->db->nDb );
+  assert( pParse->db->aDb[iDb].pBt!=0 || iDb==1 );
+  assert( iDb<SQLITE_MAX_ATTACHED+2 );
+  assert( sqlite3SchemaMutexHeld(pParse->db, iDb, 0) );
+  if( DbMaskTest(pToplevel->cookieMask, iDb)==0 ){
+    DbMaskSet(pToplevel->cookieMask, iDb);
+    if( !OMIT_TEMPDB && iDb==1 ){
+      sqlite3OpenTempDatabase(pToplevel);
+    }
+  }
+}
+
+/*
+** If argument zDb is NULL, then call sqlite3CodeVerifySchema() for each 
+** attached database. Otherwise, invoke it for the database named zDb only.
+*/
+SQLITE_PRIVATE void sqlite3CodeVerifyNamedSchema(Parse *pParse, const char *zDb){
+  sqlite3 *db = pParse->db;
+  int i;
+  for(i=0; i<db->nDb; i++){
+    Db *pDb = &db->aDb[i];
+    if( pDb->pBt && (!zDb || 0==sqlite3StrICmp(zDb, pDb->zDbSName)) ){
+      sqlite3CodeVerifySchema(pParse, i);
+    }
+  }
+}
+
+/*
+** Generate VDBE code that prepares for doing an operation that
+** might change the database.
+**
+** This routine starts a new transaction if we are not already within
+** a transaction.  If we are already within a transaction, then a checkpoint
+** is set if the setStatement parameter is true.  A checkpoint should
+** be set for operations that might fail (due to a constraint) part of
+** the way through and which will need to undo some writes without having to
+** rollback the whole transaction.  For operations where all constraints
+** can be checked before any changes are made to the database, it is never
+** necessary to undo a write and the checkpoint should not be set.
+*/
+SQLITE_PRIVATE void sqlite3BeginWriteOperation(Parse *pParse, int setStatement, int iDb){
+  Parse *pToplevel = sqlite3ParseToplevel(pParse);
+  sqlite3CodeVerifySchema(pParse, iDb);
+  DbMaskSet(pToplevel->writeMask, iDb);
+  pToplevel->isMultiWrite |= setStatement;
+}
+
+/*
+** Indicate that the statement currently under construction might write
+** more than one entry (example: deleting one row then inserting another,
+** inserting multiple rows in a table, or inserting a row and index entries.)
+** If an abort occurs after some of these writes have completed, then it will
+** be necessary to undo the completed writes.
+*/
+SQLITE_PRIVATE void sqlite3MultiWrite(Parse *pParse){
+  Parse *pToplevel = sqlite3ParseToplevel(pParse);
+  pToplevel->isMultiWrite = 1;
+}
+
+/* 
+** The code generator calls this routine if is discovers that it is
+** possible to abort a statement prior to completion.  In order to 
+** perform this abort without corrupting the database, we need to make
+** sure that the statement is protected by a statement transaction.
+**
+** Technically, we only need to set the mayAbort flag if the
+** isMultiWrite flag was previously set.  There is a time dependency
+** such that the abort must occur after the multiwrite.  This makes
+** some statements involving the REPLACE conflict resolution algorithm
+** go a little faster.  But taking advantage of this time dependency
+** makes it more difficult to prove that the code is correct (in 
+** particular, it prevents us from writing an effective
+** implementation of sqlite3AssertMayAbort()) and so we have chosen
+** to take the safe route and skip the optimization.
+*/
+SQLITE_PRIVATE void sqlite3MayAbort(Parse *pParse){
+  Parse *pToplevel = sqlite3ParseToplevel(pParse);
+  pToplevel->mayAbort = 1;
+}
+
+/*
+** Code an OP_Halt that causes the vdbe to return an SQLITE_CONSTRAINT
+** error. The onError parameter determines which (if any) of the statement
+** and/or current transaction is rolled back.
+*/
+SQLITE_PRIVATE void sqlite3HaltConstraint(
+  Parse *pParse,    /* Parsing context */
+  int errCode,      /* extended error code */
+  int onError,      /* Constraint type */
+  char *p4,         /* Error message */
+  i8 p4type,        /* P4_STATIC or P4_TRANSIENT */
+  u8 p5Errmsg       /* P5_ErrMsg type */
+){
+  Vdbe *v = sqlite3GetVdbe(pParse);
+  assert( (errCode&0xff)==SQLITE_CONSTRAINT );
+  if( onError==OE_Abort ){
+    sqlite3MayAbort(pParse);
+  }
+  sqlite3VdbeAddOp4(v, OP_Halt, errCode, onError, 0, p4, p4type);
+  sqlite3VdbeChangeP5(v, p5Errmsg);
+}
+
+/*
+** Code an OP_Halt due to UNIQUE or PRIMARY KEY constraint violation.
+*/
+SQLITE_PRIVATE void sqlite3UniqueConstraint(
+  Parse *pParse,    /* Parsing context */
+  int onError,      /* Constraint type */
+  Index *pIdx       /* The index that triggers the constraint */
+){
+  char *zErr;
+  int j;
+  StrAccum errMsg;
+  Table *pTab = pIdx->pTable;
+
+  sqlite3StrAccumInit(&errMsg, pParse->db, 0, 0, 200);
+  if( pIdx->aColExpr ){
+    sqlite3XPrintf(&errMsg, "index '%q'", pIdx->zName);
+  }else{
+    for(j=0; j<pIdx->nKeyCol; j++){
+      char *zCol;
+      assert( pIdx->aiColumn[j]>=0 );
+      zCol = pTab->aCol[pIdx->aiColumn[j]].zName;
+      if( j ) sqlite3StrAccumAppend(&errMsg, ", ", 2);
+      sqlite3XPrintf(&errMsg, "%s.%s", pTab->zName, zCol);
+    }
+  }
+  zErr = sqlite3StrAccumFinish(&errMsg);
+  sqlite3HaltConstraint(pParse, 
+    IsPrimaryKeyIndex(pIdx) ? SQLITE_CONSTRAINT_PRIMARYKEY 
+                            : SQLITE_CONSTRAINT_UNIQUE,
+    onError, zErr, P4_DYNAMIC, P5_ConstraintUnique);
+}
+
+
+/*
+** Code an OP_Halt due to non-unique rowid.
+*/
+SQLITE_PRIVATE void sqlite3RowidConstraint(
+  Parse *pParse,    /* Parsing context */
+  int onError,      /* Conflict resolution algorithm */
+  Table *pTab       /* The table with the non-unique rowid */ 
+){
+  char *zMsg;
+  int rc;
+  if( pTab->iPKey>=0 ){
+    zMsg = sqlite3MPrintf(pParse->db, "%s.%s", pTab->zName,
+                          pTab->aCol[pTab->iPKey].zName);
+    rc = SQLITE_CONSTRAINT_PRIMARYKEY;
+  }else{
+    zMsg = sqlite3MPrintf(pParse->db, "%s.rowid", pTab->zName);
+    rc = SQLITE_CONSTRAINT_ROWID;
+  }
+  sqlite3HaltConstraint(pParse, rc, onError, zMsg, P4_DYNAMIC,
+                        P5_ConstraintUnique);
+}
+
+/*
+** Check to see if pIndex uses the collating sequence pColl.  Return
+** true if it does and false if it does not.
+*/
+#ifndef SQLITE_OMIT_REINDEX
+static int collationMatch(const char *zColl, Index *pIndex){
+  int i;
+  assert( zColl!=0 );
+  for(i=0; i<pIndex->nColumn; i++){
+    const char *z = pIndex->azColl[i];
+    assert( z!=0 || pIndex->aiColumn[i]<0 );
+    if( pIndex->aiColumn[i]>=0 && 0==sqlite3StrICmp(z, zColl) ){
+      return 1;
+    }
+  }
+  return 0;
+}
+#endif
+
+/*
+** Recompute all indices of pTab that use the collating sequence pColl.
+** If pColl==0 then recompute all indices of pTab.
+*/
+#ifndef SQLITE_OMIT_REINDEX
+static void reindexTable(Parse *pParse, Table *pTab, char const *zColl){
+  Index *pIndex;              /* An index associated with pTab */
+
+  for(pIndex=pTab->pIndex; pIndex; pIndex=pIndex->pNext){
+    if( zColl==0 || collationMatch(zColl, pIndex) ){
+      int iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
+      sqlite3BeginWriteOperation(pParse, 0, iDb);
+      sqlite3RefillIndex(pParse, pIndex, -1);
+    }
+  }
+}
+#endif
+
+/*
+** Recompute all indices of all tables in all databases where the
+** indices use the collating sequence pColl.  If pColl==0 then recompute
+** all indices everywhere.
+*/
+#ifndef SQLITE_OMIT_REINDEX
+static void reindexDatabases(Parse *pParse, char const *zColl){
+  Db *pDb;                    /* A single database */
+  int iDb;                    /* The database index number */
+  sqlite3 *db = pParse->db;   /* The database connection */
+  HashElem *k;                /* For looping over tables in pDb */
+  Table *pTab;                /* A table in the database */
+
+  assert( sqlite3BtreeHoldsAllMutexes(db) );  /* Needed for schema access */
+  for(iDb=0, pDb=db->aDb; iDb<db->nDb; iDb++, pDb++){
+    assert( pDb!=0 );
+    for(k=sqliteHashFirst(&pDb->pSchema->tblHash);  k; k=sqliteHashNext(k)){
+      pTab = (Table*)sqliteHashData(k);
+      reindexTable(pParse, pTab, zColl);
+    }
+  }
+}
+#endif
+
+/*
+** Generate code for the REINDEX command.
+**
+**        REINDEX                            -- 1
+**        REINDEX  <collation>               -- 2
+**        REINDEX  ?<database>.?<tablename>  -- 3
+**        REINDEX  ?<database>.?<indexname>  -- 4
+**
+** Form 1 causes all indices in all attached databases to be rebuilt.
+** Form 2 rebuilds all indices in all databases that use the named
+** collating function.  Forms 3 and 4 rebuild the named index or all
+** indices associated with the named table.
+*/
+#ifndef SQLITE_OMIT_REINDEX
+SQLITE_PRIVATE void sqlite3Reindex(Parse *pParse, Token *pName1, Token *pName2){
+  CollSeq *pColl;             /* Collating sequence to be reindexed, or NULL */
+  char *z;                    /* Name of a table or index */
+  const char *zDb;            /* Name of the database */
+  Table *pTab;                /* A table in the database */
+  Index *pIndex;              /* An index associated with pTab */
+  int iDb;                    /* The database index number */
+  sqlite3 *db = pParse->db;   /* The database connection */
+  Token *pObjName;            /* Name of the table or index to be reindexed */
+
+  /* Read the database schema. If an error occurs, leave an error message
+  ** and code in pParse and return NULL. */
+  if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
+    return;
+  }
+
+  if( pName1==0 ){
+    reindexDatabases(pParse, 0);
+    return;
+  }else if( NEVER(pName2==0) || pName2->z==0 ){
+    char *zColl;
+    assert( pName1->z );
+    zColl = sqlite3NameFromToken(pParse->db, pName1);
+    if( !zColl ) return;
+    pColl = sqlite3FindCollSeq(db, ENC(db), zColl, 0);
+    if( pColl ){
+      reindexDatabases(pParse, zColl);
+      sqlite3DbFree(db, zColl);
+      return;
+    }
+    sqlite3DbFree(db, zColl);
+  }
+  iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pObjName);
+  if( iDb<0 ) return;
+  z = sqlite3NameFromToken(db, pObjName);
+  if( z==0 ) return;
+  zDb = db->aDb[iDb].zDbSName;
+  pTab = sqlite3FindTable(db, z, zDb);
+  if( pTab ){
+    reindexTable(pParse, pTab, 0);
+    sqlite3DbFree(db, z);
+    return;
+  }
+  pIndex = sqlite3FindIndex(db, z, zDb);
+  sqlite3DbFree(db, z);
+  if( pIndex ){
+    sqlite3BeginWriteOperation(pParse, 0, iDb);
+    sqlite3RefillIndex(pParse, pIndex, -1);
+    return;
+  }
+  sqlite3ErrorMsg(pParse, "unable to identify the object to be reindexed");
+}
+#endif
+
+/*
+** Return a KeyInfo structure that is appropriate for the given Index.
+**
+** The caller should invoke sqlite3KeyInfoUnref() on the returned object
+** when it has finished using it.
+*/
+SQLITE_PRIVATE KeyInfo *sqlite3KeyInfoOfIndex(Parse *pParse, Index *pIdx){
+  int i;
+  int nCol = pIdx->nColumn;
+  int nKey = pIdx->nKeyCol;
+  KeyInfo *pKey;
+  if( pParse->nErr ) return 0;
+  if( pIdx->uniqNotNull ){
+    pKey = sqlite3KeyInfoAlloc(pParse->db, nKey, nCol-nKey);
+  }else{
+    pKey = sqlite3KeyInfoAlloc(pParse->db, nCol, 0);
+  }
+  if( pKey ){
+    assert( sqlite3KeyInfoIsWriteable(pKey) );
+    for(i=0; i<nCol; i++){
+      const char *zColl = pIdx->azColl[i];
+      pKey->aColl[i] = zColl==sqlite3StrBINARY ? 0 :
+                        sqlite3LocateCollSeq(pParse, zColl);
+      pKey->aSortOrder[i] = pIdx->aSortOrder[i];
+    }
+    if( pParse->nErr ){
+      sqlite3KeyInfoUnref(pKey);
+      pKey = 0;
+    }
+  }
+  return pKey;
+}
+
+#ifndef SQLITE_OMIT_CTE
+/* 
+** This routine is invoked once per CTE by the parser while parsing a 
+** WITH clause. 
+*/
+SQLITE_PRIVATE With *sqlite3WithAdd(
+  Parse *pParse,          /* Parsing context */
+  With *pWith,            /* Existing WITH clause, or NULL */
+  Token *pName,           /* Name of the common-table */
+  ExprList *pArglist,     /* Optional column name list for the table */
+  Select *pQuery          /* Query used to initialize the table */
+){
+  sqlite3 *db = pParse->db;
+  With *pNew;
+  char *zName;
+
+  /* Check that the CTE name is unique within this WITH clause. If
+  ** not, store an error in the Parse structure. */
+  zName = sqlite3NameFromToken(pParse->db, pName);
+  if( zName && pWith ){
+    int i;
+    for(i=0; i<pWith->nCte; i++){
+      if( sqlite3StrICmp(zName, pWith->a[i].zName)==0 ){
+        sqlite3ErrorMsg(pParse, "duplicate WITH table name: %s", zName);
+      }
+    }
+  }
+
+  if( pWith ){
+    int nByte = sizeof(*pWith) + (sizeof(pWith->a[1]) * pWith->nCte);
+    pNew = sqlite3DbRealloc(db, pWith, nByte);
+  }else{
+    pNew = sqlite3DbMallocZero(db, sizeof(*pWith));
+  }
+  assert( (pNew!=0 && zName!=0) || db->mallocFailed );
+
+  if( db->mallocFailed ){
+    sqlite3ExprListDelete(db, pArglist);
+    sqlite3SelectDelete(db, pQuery);
+    sqlite3DbFree(db, zName);
+    pNew = pWith;
+  }else{
+    pNew->a[pNew->nCte].pSelect = pQuery;
+    pNew->a[pNew->nCte].pCols = pArglist;
+    pNew->a[pNew->nCte].zName = zName;
+    pNew->a[pNew->nCte].zCteErr = 0;
+    pNew->nCte++;
+  }
+
+  return pNew;
+}
+
+/*
+** Free the contents of the With object passed as the second argument.
+*/
+SQLITE_PRIVATE void sqlite3WithDelete(sqlite3 *db, With *pWith){
+  if( pWith ){
+    int i;
+    for(i=0; i<pWith->nCte; i++){
+      struct Cte *pCte = &pWith->a[i];
+      sqlite3ExprListDelete(db, pCte->pCols);
+      sqlite3SelectDelete(db, pCte->pSelect);
+      sqlite3DbFree(db, pCte->zName);
+    }
+    sqlite3DbFree(db, pWith);
+  }
+}
+#endif /* !defined(SQLITE_OMIT_CTE) */
+
+/************** End of build.c ***********************************************/
+/************** Begin file callback.c ****************************************/
+/*
+** 2005 May 23 
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains functions used to access the internal hash tables
+** of user defined functions and collation sequences.
+*/
+
+/* #include "sqliteInt.h" */
+
+/*
+** Invoke the 'collation needed' callback to request a collation sequence
+** in the encoding enc of name zName, length nName.
+*/
+static void callCollNeeded(sqlite3 *db, int enc, const char *zName){
+  assert( !db->xCollNeeded || !db->xCollNeeded16 );
+  if( db->xCollNeeded ){
+    char *zExternal = sqlite3DbStrDup(db, zName);
+    if( !zExternal ) return;
+    db->xCollNeeded(db->pCollNeededArg, db, enc, zExternal);
+    sqlite3DbFree(db, zExternal);
+  }
+#ifndef SQLITE_OMIT_UTF16
+  if( db->xCollNeeded16 ){
+    char const *zExternal;
+    sqlite3_value *pTmp = sqlite3ValueNew(db);
+    sqlite3ValueSetStr(pTmp, -1, zName, SQLITE_UTF8, SQLITE_STATIC);
+    zExternal = sqlite3ValueText(pTmp, SQLITE_UTF16NATIVE);
+    if( zExternal ){
+      db->xCollNeeded16(db->pCollNeededArg, db, (int)ENC(db), zExternal);
+    }
+    sqlite3ValueFree(pTmp);
+  }
+#endif
+}
+
+/*
+** This routine is called if the collation factory fails to deliver a
+** collation function in the best encoding but there may be other versions
+** of this collation function (for other text encodings) available. Use one
+** of these instead if they exist. Avoid a UTF-8 <-> UTF-16 conversion if
+** possible.
+*/
+static int synthCollSeq(sqlite3 *db, CollSeq *pColl){
+  CollSeq *pColl2;
+  char *z = pColl->zName;
+  int i;
+  static const u8 aEnc[] = { SQLITE_UTF16BE, SQLITE_UTF16LE, SQLITE_UTF8 };
+  for(i=0; i<3; i++){
+    pColl2 = sqlite3FindCollSeq(db, aEnc[i], z, 0);
+    if( pColl2->xCmp!=0 ){
+      memcpy(pColl, pColl2, sizeof(CollSeq));
+      pColl->xDel = 0;         /* Do not copy the destructor */
+      return SQLITE_OK;
+    }
+  }
+  return SQLITE_ERROR;
+}
+
+/*
+** This function is responsible for invoking the collation factory callback
+** or substituting a collation sequence of a different encoding when the
+** requested collation sequence is not available in the desired encoding.
+** 
+** If it is not NULL, then pColl must point to the database native encoding 
+** collation sequence with name zName, length nName.
+**
+** The return value is either the collation sequence to be used in database
+** db for collation type name zName, length nName, or NULL, if no collation
+** sequence can be found.  If no collation is found, leave an error message.
+**
+** See also: sqlite3LocateCollSeq(), sqlite3FindCollSeq()
+*/
+SQLITE_PRIVATE CollSeq *sqlite3GetCollSeq(
+  Parse *pParse,        /* Parsing context */
+  u8 enc,               /* The desired encoding for the collating sequence */
+  CollSeq *pColl,       /* Collating sequence with native encoding, or NULL */
+  const char *zName     /* Collating sequence name */
+){
+  CollSeq *p;
+  sqlite3 *db = pParse->db;
+
+  p = pColl;
+  if( !p ){
+    p = sqlite3FindCollSeq(db, enc, zName, 0);
+  }
+  if( !p || !p->xCmp ){
+    /* No collation sequence of this type for this encoding is registered.
+    ** Call the collation factory to see if it can supply us with one.
+    */
+    callCollNeeded(db, enc, zName);
+    p = sqlite3FindCollSeq(db, enc, zName, 0);
+  }
+  if( p && !p->xCmp && synthCollSeq(db, p) ){
+    p = 0;
+  }
+  assert( !p || p->xCmp );
+  if( p==0 ){
+    sqlite3ErrorMsg(pParse, "no such collation sequence: %s", zName);
+  }
+  return p;
+}
+
+/*
+** This routine is called on a collation sequence before it is used to
+** check that it is defined. An undefined collation sequence exists when
+** a database is loaded that contains references to collation sequences
+** that have not been defined by sqlite3_create_collation() etc.
+**
+** If required, this routine calls the 'collation needed' callback to
+** request a definition of the collating sequence. If this doesn't work, 
+** an equivalent collating sequence that uses a text encoding different
+** from the main database is substituted, if one is available.
+*/
+SQLITE_PRIVATE int sqlite3CheckCollSeq(Parse *pParse, CollSeq *pColl){
+  if( pColl ){
+    const char *zName = pColl->zName;
+    sqlite3 *db = pParse->db;
+    CollSeq *p = sqlite3GetCollSeq(pParse, ENC(db), pColl, zName);
+    if( !p ){
+      return SQLITE_ERROR;
+    }
+    assert( p==pColl );
+  }
+  return SQLITE_OK;
+}
+
+
+
+/*
+** Locate and return an entry from the db.aCollSeq hash table. If the entry
+** specified by zName and nName is not found and parameter 'create' is
+** true, then create a new entry. Otherwise return NULL.
+**
+** Each pointer stored in the sqlite3.aCollSeq hash table contains an
+** array of three CollSeq structures. The first is the collation sequence
+** preferred for UTF-8, the second UTF-16le, and the third UTF-16be.
+**
+** Stored immediately after the three collation sequences is a copy of
+** the collation sequence name. A pointer to this string is stored in
+** each collation sequence structure.
+*/
+static CollSeq *findCollSeqEntry(
+  sqlite3 *db,          /* Database connection */
+  const char *zName,    /* Name of the collating sequence */
+  int create            /* Create a new entry if true */
+){
+  CollSeq *pColl;
+  pColl = sqlite3HashFind(&db->aCollSeq, zName);
+
+  if( 0==pColl && create ){
+    int nName = sqlite3Strlen30(zName);
+    pColl = sqlite3DbMallocZero(db, 3*sizeof(*pColl) + nName + 1);
+    if( pColl ){
+      CollSeq *pDel = 0;
+      pColl[0].zName = (char*)&pColl[3];
+      pColl[0].enc = SQLITE_UTF8;
+      pColl[1].zName = (char*)&pColl[3];
+      pColl[1].enc = SQLITE_UTF16LE;
+      pColl[2].zName = (char*)&pColl[3];
+      pColl[2].enc = SQLITE_UTF16BE;
+      memcpy(pColl[0].zName, zName, nName);
+      pColl[0].zName[nName] = 0;
+      pDel = sqlite3HashInsert(&db->aCollSeq, pColl[0].zName, pColl);
+
+      /* If a malloc() failure occurred in sqlite3HashInsert(), it will 
+      ** return the pColl pointer to be deleted (because it wasn't added
+      ** to the hash table).
+      */
+      assert( pDel==0 || pDel==pColl );
+      if( pDel!=0 ){
+        sqlite3OomFault(db);
+        sqlite3DbFree(db, pDel);
+        pColl = 0;
+      }
+    }
+  }
+  return pColl;
+}
+
+/*
+** Parameter zName points to a UTF-8 encoded string nName bytes long.
+** Return the CollSeq* pointer for the collation sequence named zName
+** for the encoding 'enc' from the database 'db'.
+**
+** If the entry specified is not found and 'create' is true, then create a
+** new entry.  Otherwise return NULL.
+**
+** A separate function sqlite3LocateCollSeq() is a wrapper around
+** this routine.  sqlite3LocateCollSeq() invokes the collation factory
+** if necessary and generates an error message if the collating sequence
+** cannot be found.
+**
+** See also: sqlite3LocateCollSeq(), sqlite3GetCollSeq()
+*/
+SQLITE_PRIVATE CollSeq *sqlite3FindCollSeq(
+  sqlite3 *db,
+  u8 enc,
+  const char *zName,
+  int create
+){
+  CollSeq *pColl;
+  if( zName ){
+    pColl = findCollSeqEntry(db, zName, create);
+  }else{
+    pColl = db->pDfltColl;
+  }
+  assert( SQLITE_UTF8==1 && SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
+  assert( enc>=SQLITE_UTF8 && enc<=SQLITE_UTF16BE );
+  if( pColl ) pColl += enc-1;
+  return pColl;
+}
+
+/* During the search for the best function definition, this procedure
+** is called to test how well the function passed as the first argument
+** matches the request for a function with nArg arguments in a system
+** that uses encoding enc. The value returned indicates how well the
+** request is matched. A higher value indicates a better match.
+**
+** If nArg is -1 that means to only return a match (non-zero) if p->nArg
+** is also -1.  In other words, we are searching for a function that
+** takes a variable number of arguments.
+**
+** If nArg is -2 that means that we are searching for any function 
+** regardless of the number of arguments it uses, so return a positive
+** match score for any
+**
+** The returned value is always between 0 and 6, as follows:
+**
+** 0: Not a match.
+** 1: UTF8/16 conversion required and function takes any number of arguments.
+** 2: UTF16 byte order change required and function takes any number of args.
+** 3: encoding matches and function takes any number of arguments
+** 4: UTF8/16 conversion required - argument count matches exactly
+** 5: UTF16 byte order conversion required - argument count matches exactly
+** 6: Perfect match:  encoding and argument count match exactly.
+**
+** If nArg==(-2) then any function with a non-null xSFunc is
+** a perfect match and any function with xSFunc NULL is
+** a non-match.
+*/
+#define FUNC_PERFECT_MATCH 6  /* The score for a perfect match */
+static int matchQuality(
+  FuncDef *p,     /* The function we are evaluating for match quality */
+  int nArg,       /* Desired number of arguments.  (-1)==any */
+  u8 enc          /* Desired text encoding */
+){
+  int match;
+
+  /* nArg of -2 is a special case */
+  if( nArg==(-2) ) return (p->xSFunc==0) ? 0 : FUNC_PERFECT_MATCH;
+
+  /* Wrong number of arguments means "no match" */
+  if( p->nArg!=nArg && p->nArg>=0 ) return 0;
+
+  /* Give a better score to a function with a specific number of arguments
+  ** than to function that accepts any number of arguments. */
+  if( p->nArg==nArg ){
+    match = 4;
+  }else{
+    match = 1;
+  }
+
+  /* Bonus points if the text encoding matches */
+  if( enc==(p->funcFlags & SQLITE_FUNC_ENCMASK) ){
+    match += 2;  /* Exact encoding match */
+  }else if( (enc & p->funcFlags & 2)!=0 ){
+    match += 1;  /* Both are UTF16, but with different byte orders */
+  }
+
+  return match;
+}
+
+/*
+** Search a FuncDefHash for a function with the given name.  Return
+** a pointer to the matching FuncDef if found, or 0 if there is no match.
+*/
+static FuncDef *functionSearch(
+  int h,               /* Hash of the name */
+  const char *zFunc    /* Name of function */
+){
+  FuncDef *p;
+  for(p=sqlite3BuiltinFunctions.a[h]; p; p=p->u.pHash){
+    if( sqlite3StrICmp(p->zName, zFunc)==0 ){
+      return p;
+    }
+  }
+  return 0;
+}
+
+/*
+** Insert a new FuncDef into a FuncDefHash hash table.
+*/
+SQLITE_PRIVATE void sqlite3InsertBuiltinFuncs(
+  FuncDef *aDef,      /* List of global functions to be inserted */
+  int nDef            /* Length of the apDef[] list */
+){
+  int i;
+  for(i=0; i<nDef; i++){
+    FuncDef *pOther;
+    const char *zName = aDef[i].zName;
+    int nName = sqlite3Strlen30(zName);
+    int h = (sqlite3UpperToLower[(u8)zName[0]] + nName) % SQLITE_FUNC_HASH_SZ;
+    pOther = functionSearch(h, zName);
+    if( pOther ){
+      assert( pOther!=&aDef[i] && pOther->pNext!=&aDef[i] );
+      aDef[i].pNext = pOther->pNext;
+      pOther->pNext = &aDef[i];
+    }else{
+      aDef[i].pNext = 0;
+      aDef[i].u.pHash = sqlite3BuiltinFunctions.a[h];
+      sqlite3BuiltinFunctions.a[h] = &aDef[i];
+    }
+  }
+}
+  
+  
+
+/*
+** Locate a user function given a name, a number of arguments and a flag
+** indicating whether the function prefers UTF-16 over UTF-8.  Return a
+** pointer to the FuncDef structure that defines that function, or return
+** NULL if the function does not exist.
+**
+** If the createFlag argument is true, then a new (blank) FuncDef
+** structure is created and liked into the "db" structure if a
+** no matching function previously existed.
+**
+** If nArg is -2, then the first valid function found is returned.  A
+** function is valid if xSFunc is non-zero.  The nArg==(-2)
+** case is used to see if zName is a valid function name for some number
+** of arguments.  If nArg is -2, then createFlag must be 0.
+**
+** If createFlag is false, then a function with the required name and
+** number of arguments may be returned even if the eTextRep flag does not
+** match that requested.
+*/
+SQLITE_PRIVATE FuncDef *sqlite3FindFunction(
+  sqlite3 *db,       /* An open database */
+  const char *zName, /* Name of the function.  zero-terminated */
+  int nArg,          /* Number of arguments.  -1 means any number */
+  u8 enc,            /* Preferred text encoding */
+  u8 createFlag      /* Create new entry if true and does not otherwise exist */
+){
+  FuncDef *p;         /* Iterator variable */
+  FuncDef *pBest = 0; /* Best match found so far */
+  int bestScore = 0;  /* Score of best match */
+  int h;              /* Hash value */
+  int nName;          /* Length of the name */
+
+  assert( nArg>=(-2) );
+  assert( nArg>=(-1) || createFlag==0 );
+  nName = sqlite3Strlen30(zName);
+
+  /* First search for a match amongst the application-defined functions.
+  */
+  p = (FuncDef*)sqlite3HashFind(&db->aFunc, zName);
+  while( p ){
+    int score = matchQuality(p, nArg, enc);
+    if( score>bestScore ){
+      pBest = p;
+      bestScore = score;
+    }
+    p = p->pNext;
+  }
+
+  /* If no match is found, search the built-in functions.
+  **
+  ** If the SQLITE_PreferBuiltin flag is set, then search the built-in
+  ** functions even if a prior app-defined function was found.  And give
+  ** priority to built-in functions.
+  **
+  ** Except, if createFlag is true, that means that we are trying to
+  ** install a new function.  Whatever FuncDef structure is returned it will
+  ** have fields overwritten with new information appropriate for the
+  ** new function.  But the FuncDefs for built-in functions are read-only.
+  ** So we must not search for built-ins when creating a new function.
+  */ 
+  if( !createFlag && (pBest==0 || (db->flags & SQLITE_PreferBuiltin)!=0) ){
+    bestScore = 0;
+    h = (sqlite3UpperToLower[(u8)zName[0]] + nName) % SQLITE_FUNC_HASH_SZ;
+    p = functionSearch(h, zName);
+    while( p ){
+      int score = matchQuality(p, nArg, enc);
+      if( score>bestScore ){
+        pBest = p;
+        bestScore = score;
+      }
+      p = p->pNext;
+    }
+  }
+
+  /* If the createFlag parameter is true and the search did not reveal an
+  ** exact match for the name, number of arguments and encoding, then add a
+  ** new entry to the hash table and return it.
+  */
+  if( createFlag && bestScore<FUNC_PERFECT_MATCH && 
+      (pBest = sqlite3DbMallocZero(db, sizeof(*pBest)+nName+1))!=0 ){
+    FuncDef *pOther;
+    pBest->zName = (const char*)&pBest[1];
+    pBest->nArg = (u16)nArg;
+    pBest->funcFlags = enc;
+    memcpy((char*)&pBest[1], zName, nName+1);
+    pOther = (FuncDef*)sqlite3HashInsert(&db->aFunc, pBest->zName, pBest);
+    if( pOther==pBest ){
+      sqlite3DbFree(db, pBest);
+      sqlite3OomFault(db);
+      return 0;
+    }else{
+      pBest->pNext = pOther;
+    }
+  }
+
+  if( pBest && (pBest->xSFunc || createFlag) ){
+    return pBest;
+  }
+  return 0;
+}
+
+/*
+** Free all resources held by the schema structure. The void* argument points
+** at a Schema struct. This function does not call sqlite3DbFree(db, ) on the 
+** pointer itself, it just cleans up subsidiary resources (i.e. the contents
+** of the schema hash tables).
+**
+** The Schema.cache_size variable is not cleared.
+*/
+SQLITE_PRIVATE void sqlite3SchemaClear(void *p){
+  Hash temp1;
+  Hash temp2;
+  HashElem *pElem;
+  Schema *pSchema = (Schema *)p;
+
+  temp1 = pSchema->tblHash;
+  temp2 = pSchema->trigHash;
+  sqlite3HashInit(&pSchema->trigHash);
+  sqlite3HashClear(&pSchema->idxHash);
+  for(pElem=sqliteHashFirst(&temp2); pElem; pElem=sqliteHashNext(pElem)){
+    sqlite3DeleteTrigger(0, (Trigger*)sqliteHashData(pElem));
+  }
+  sqlite3HashClear(&temp2);
+  sqlite3HashInit(&pSchema->tblHash);
+  for(pElem=sqliteHashFirst(&temp1); pElem; pElem=sqliteHashNext(pElem)){
+    Table *pTab = sqliteHashData(pElem);
+    sqlite3DeleteTable(0, pTab);
+  }
+  sqlite3HashClear(&temp1);
+  sqlite3HashClear(&pSchema->fkeyHash);
+  pSchema->pSeqTab = 0;
+  if( pSchema->schemaFlags & DB_SchemaLoaded ){
+    pSchema->iGeneration++;
+    pSchema->schemaFlags &= ~DB_SchemaLoaded;
+  }
+}
+
+/*
+** Find and return the schema associated with a BTree.  Create
+** a new one if necessary.
+*/
+SQLITE_PRIVATE Schema *sqlite3SchemaGet(sqlite3 *db, Btree *pBt){
+  Schema * p;
+  if( pBt ){
+    p = (Schema *)sqlite3BtreeSchema(pBt, sizeof(Schema), sqlite3SchemaClear);
+  }else{
+    p = (Schema *)sqlite3DbMallocZero(0, sizeof(Schema));
+  }
+  if( !p ){
+    sqlite3OomFault(db);
+  }else if ( 0==p->file_format ){
+    sqlite3HashInit(&p->tblHash);
+    sqlite3HashInit(&p->idxHash);
+    sqlite3HashInit(&p->trigHash);
+    sqlite3HashInit(&p->fkeyHash);
+    p->enc = SQLITE_UTF8;
+  }
+  return p;
+}
+
+/************** End of callback.c ********************************************/
+/************** Begin file delete.c ******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains C code routines that are called by the parser
+** in order to generate code for DELETE FROM statements.
+*/
+/* #include "sqliteInt.h" */
+
+/*
+** While a SrcList can in general represent multiple tables and subqueries
+** (as in the FROM clause of a SELECT statement) in this case it contains
+** the name of a single table, as one might find in an INSERT, DELETE,
+** or UPDATE statement.  Look up that table in the symbol table and
+** return a pointer.  Set an error message and return NULL if the table 
+** name is not found or if any other error occurs.
+**
+** The following fields are initialized appropriate in pSrc:
+**
+**    pSrc->a[0].pTab       Pointer to the Table object
+**    pSrc->a[0].pIndex     Pointer to the INDEXED BY index, if there is one
+**
+*/
+SQLITE_PRIVATE Table *sqlite3SrcListLookup(Parse *pParse, SrcList *pSrc){
+  struct SrcList_item *pItem = pSrc->a;
+  Table *pTab;
+  assert( pItem && pSrc->nSrc==1 );
+  pTab = sqlite3LocateTableItem(pParse, 0, pItem);
+  sqlite3DeleteTable(pParse->db, pItem->pTab);
+  pItem->pTab = pTab;
+  if( pTab ){
+    pTab->nRef++;
+  }
+  if( sqlite3IndexedByLookup(pParse, pItem) ){
+    pTab = 0;
+  }
+  return pTab;
+}
+
+/*
+** Check to make sure the given table is writable.  If it is not
+** writable, generate an error message and return 1.  If it is
+** writable return 0;
+*/
+SQLITE_PRIVATE int sqlite3IsReadOnly(Parse *pParse, Table *pTab, int viewOk){
+  /* A table is not writable under the following circumstances:
+  **
+  **   1) It is a virtual table and no implementation of the xUpdate method
+  **      has been provided, or
+  **   2) It is a system table (i.e. sqlite_master), this call is not
+  **      part of a nested parse and writable_schema pragma has not 
+  **      been specified.
+  **
+  ** In either case leave an error message in pParse and return non-zero.
+  */
+  if( ( IsVirtual(pTab) 
+     && sqlite3GetVTable(pParse->db, pTab)->pMod->pModule->xUpdate==0 )
+   || ( (pTab->tabFlags & TF_Readonly)!=0
+     && (pParse->db->flags & SQLITE_WriteSchema)==0
+     && pParse->nested==0 )
+  ){
+    sqlite3ErrorMsg(pParse, "table %s may not be modified", pTab->zName);
+    return 1;
+  }
+
+#ifndef SQLITE_OMIT_VIEW
+  if( !viewOk && pTab->pSelect ){
+    sqlite3ErrorMsg(pParse,"cannot modify %s because it is a view",pTab->zName);
+    return 1;
+  }
+#endif
+  return 0;
+}
+
+
+#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
+/*
+** Evaluate a view and store its result in an ephemeral table.  The
+** pWhere argument is an optional WHERE clause that restricts the
+** set of rows in the view that are to be added to the ephemeral table.
+*/
+SQLITE_PRIVATE void sqlite3MaterializeView(
+  Parse *pParse,       /* Parsing context */
+  Table *pView,        /* View definition */
+  Expr *pWhere,        /* Optional WHERE clause to be added */
+  int iCur             /* Cursor number for ephemeral table */
+){
+  SelectDest dest;
+  Select *pSel;
+  SrcList *pFrom;
+  sqlite3 *db = pParse->db;
+  int iDb = sqlite3SchemaToIndex(db, pView->pSchema);
+  pWhere = sqlite3ExprDup(db, pWhere, 0);
+  pFrom = sqlite3SrcListAppend(db, 0, 0, 0);
+  if( pFrom ){
+    assert( pFrom->nSrc==1 );
+    pFrom->a[0].zName = sqlite3DbStrDup(db, pView->zName);
+    pFrom->a[0].zDatabase = sqlite3DbStrDup(db, db->aDb[iDb].zDbSName);
+    assert( pFrom->a[0].pOn==0 );
+    assert( pFrom->a[0].pUsing==0 );
+  }
+  pSel = sqlite3SelectNew(pParse, 0, pFrom, pWhere, 0, 0, 0, 
+                          SF_IncludeHidden, 0, 0);
+  sqlite3SelectDestInit(&dest, SRT_EphemTab, iCur);
+  sqlite3Select(pParse, pSel, &dest);
+  sqlite3SelectDelete(db, pSel);
+}
+#endif /* !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER) */
+
+#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)
+/*
+** Generate an expression tree to implement the WHERE, ORDER BY,
+** and LIMIT/OFFSET portion of DELETE and UPDATE statements.
+**
+**     DELETE FROM table_wxyz WHERE a<5 ORDER BY a LIMIT 1;
+**                            \__________________________/
+**                               pLimitWhere (pInClause)
+*/
+SQLITE_PRIVATE Expr *sqlite3LimitWhere(
+  Parse *pParse,               /* The parser context */
+  SrcList *pSrc,               /* the FROM clause -- which tables to scan */
+  Expr *pWhere,                /* The WHERE clause.  May be null */
+  ExprList *pOrderBy,          /* The ORDER BY clause.  May be null */
+  Expr *pLimit,                /* The LIMIT clause.  May be null */
+  Expr *pOffset,               /* The OFFSET clause.  May be null */
+  char *zStmtType              /* Either DELETE or UPDATE.  For err msgs. */
+){
+  Expr *pWhereRowid = NULL;    /* WHERE rowid .. */
+  Expr *pInClause = NULL;      /* WHERE rowid IN ( select ) */
+  Expr *pSelectRowid = NULL;   /* SELECT rowid ... */
+  ExprList *pEList = NULL;     /* Expression list contaning only pSelectRowid */
+  SrcList *pSelectSrc = NULL;  /* SELECT rowid FROM x ... (dup of pSrc) */
+  Select *pSelect = NULL;      /* Complete SELECT tree */
+
+  /* Check that there isn't an ORDER BY without a LIMIT clause.
+  */
+  if( pOrderBy && (pLimit == 0) ) {
+    sqlite3ErrorMsg(pParse, "ORDER BY without LIMIT on %s", zStmtType);
+    goto limit_where_cleanup;
+  }
+
+  /* We only need to generate a select expression if there
+  ** is a limit/offset term to enforce.
+  */
+  if( pLimit == 0 ) {
+    /* if pLimit is null, pOffset will always be null as well. */
+    assert( pOffset == 0 );
+    return pWhere;
+  }
+
+  /* Generate a select expression tree to enforce the limit/offset 
+  ** term for the DELETE or UPDATE statement.  For example:
+  **   DELETE FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
+  ** becomes:
+  **   DELETE FROM table_a WHERE rowid IN ( 
+  **     SELECT rowid FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
+  **   );
+  */
+
+  pSelectRowid = sqlite3PExpr(pParse, TK_ROW, 0, 0, 0);
+  if( pSelectRowid == 0 ) goto limit_where_cleanup;
+  pEList = sqlite3ExprListAppend(pParse, 0, pSelectRowid);
+  if( pEList == 0 ) goto limit_where_cleanup;
+
+  /* duplicate the FROM clause as it is needed by both the DELETE/UPDATE tree
+  ** and the SELECT subtree. */
+  pSelectSrc = sqlite3SrcListDup(pParse->db, pSrc, 0);
+  if( pSelectSrc == 0 ) {
+    sqlite3ExprListDelete(pParse->db, pEList);
+    goto limit_where_cleanup;
+  }
+
+  /* generate the SELECT expression tree. */
+  pSelect = sqlite3SelectNew(pParse,pEList,pSelectSrc,pWhere,0,0,
+                             pOrderBy,0,pLimit,pOffset);
+  if( pSelect == 0 ) return 0;
+
+  /* now generate the new WHERE rowid IN clause for the DELETE/UDPATE */
+  pWhereRowid = sqlite3PExpr(pParse, TK_ROW, 0, 0, 0);
+  pInClause = pWhereRowid ? sqlite3PExpr(pParse, TK_IN, pWhereRowid, 0, 0) : 0;
+  sqlite3PExprAddSelect(pParse, pInClause, pSelect);
+  return pInClause;
+
+limit_where_cleanup:
+  sqlite3ExprDelete(pParse->db, pWhere);
+  sqlite3ExprListDelete(pParse->db, pOrderBy);
+  sqlite3ExprDelete(pParse->db, pLimit);
+  sqlite3ExprDelete(pParse->db, pOffset);
+  return 0;
+}
+#endif /* defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) */
+       /*      && !defined(SQLITE_OMIT_SUBQUERY) */
+
+/*
+** Generate code for a DELETE FROM statement.
+**
+**     DELETE FROM table_wxyz WHERE a<5 AND b NOT NULL;
+**                 \________/       \________________/
+**                  pTabList              pWhere
+*/
+SQLITE_PRIVATE void sqlite3DeleteFrom(
+  Parse *pParse,         /* The parser context */
+  SrcList *pTabList,     /* The table from which we should delete things */
+  Expr *pWhere           /* The WHERE clause.  May be null */
+){
+  Vdbe *v;               /* The virtual database engine */
+  Table *pTab;           /* The table from which records will be deleted */
+  int i;                 /* Loop counter */
+  WhereInfo *pWInfo;     /* Information about the WHERE clause */
+  Index *pIdx;           /* For looping over indices of the table */
+  int iTabCur;           /* Cursor number for the table */
+  int iDataCur = 0;      /* VDBE cursor for the canonical data source */
+  int iIdxCur = 0;       /* Cursor number of the first index */
+  int nIdx;              /* Number of indices */
+  sqlite3 *db;           /* Main database structure */
+  AuthContext sContext;  /* Authorization context */
+  NameContext sNC;       /* Name context to resolve expressions in */
+  int iDb;               /* Database number */
+  int memCnt = -1;       /* Memory cell used for change counting */
+  int rcauth;            /* Value returned by authorization callback */
+  int eOnePass;          /* ONEPASS_OFF or _SINGLE or _MULTI */
+  int aiCurOnePass[2];   /* The write cursors opened by WHERE_ONEPASS */
+  u8 *aToOpen = 0;       /* Open cursor iTabCur+j if aToOpen[j] is true */
+  Index *pPk;            /* The PRIMARY KEY index on the table */
+  int iPk = 0;           /* First of nPk registers holding PRIMARY KEY value */
+  i16 nPk = 1;           /* Number of columns in the PRIMARY KEY */
+  int iKey;              /* Memory cell holding key of row to be deleted */
+  i16 nKey;              /* Number of memory cells in the row key */
+  int iEphCur = 0;       /* Ephemeral table holding all primary key values */
+  int iRowSet = 0;       /* Register for rowset of rows to delete */
+  int addrBypass = 0;    /* Address of jump over the delete logic */
+  int addrLoop = 0;      /* Top of the delete loop */
+  int addrEphOpen = 0;   /* Instruction to open the Ephemeral table */
+  int bComplex;          /* True if there are triggers or FKs or
+                         ** subqueries in the WHERE clause */
+ 
+#ifndef SQLITE_OMIT_TRIGGER
+  int isView;                  /* True if attempting to delete from a view */
+  Trigger *pTrigger;           /* List of table triggers, if required */
+#endif
+
+  memset(&sContext, 0, sizeof(sContext));
+  db = pParse->db;
+  if( pParse->nErr || db->mallocFailed ){
+    goto delete_from_cleanup;
+  }
+  assert( pTabList->nSrc==1 );
+
+  /* Locate the table which we want to delete.  This table has to be
+  ** put in an SrcList structure because some of the subroutines we
+  ** will be calling are designed to work with multiple tables and expect
+  ** an SrcList* parameter instead of just a Table* parameter.
+  */
+  pTab = sqlite3SrcListLookup(pParse, pTabList);
+  if( pTab==0 )  goto delete_from_cleanup;
+
+  /* Figure out if we have any triggers and if the table being
+  ** deleted from is a view
+  */
+#ifndef SQLITE_OMIT_TRIGGER
+  pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
+  isView = pTab->pSelect!=0;
+  bComplex = pTrigger || sqlite3FkRequired(pParse, pTab, 0, 0);
+#else
+# define pTrigger 0
+# define isView 0
+#endif
+#ifdef SQLITE_OMIT_VIEW
+# undef isView
+# define isView 0
+#endif
+
+  /* If pTab is really a view, make sure it has been initialized.
+  */
+  if( sqlite3ViewGetColumnNames(pParse, pTab) ){
+    goto delete_from_cleanup;
+  }
+
+  if( sqlite3IsReadOnly(pParse, pTab, (pTrigger?1:0)) ){
+    goto delete_from_cleanup;
+  }
+  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+  assert( iDb<db->nDb );
+  rcauth = sqlite3AuthCheck(pParse, SQLITE_DELETE, pTab->zName, 0, 
+                            db->aDb[iDb].zDbSName);
+  assert( rcauth==SQLITE_OK || rcauth==SQLITE_DENY || rcauth==SQLITE_IGNORE );
+  if( rcauth==SQLITE_DENY ){
+    goto delete_from_cleanup;
+  }
+  assert(!isView || pTrigger);
+
+  /* Assign cursor numbers to the table and all its indices.
+  */
+  assert( pTabList->nSrc==1 );
+  iTabCur = pTabList->a[0].iCursor = pParse->nTab++;
+  for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdx++){
+    pParse->nTab++;
+  }
+
+  /* Start the view context
+  */
+  if( isView ){
+    sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
+  }
+
+  /* Begin generating code.
+  */
+  v = sqlite3GetVdbe(pParse);
+  if( v==0 ){
+    goto delete_from_cleanup;
+  }
+  if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
+  sqlite3BeginWriteOperation(pParse, 1, iDb);
+
+  /* If we are trying to delete from a view, realize that view into
+  ** an ephemeral table.
+  */
+#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
+  if( isView ){
+    sqlite3MaterializeView(pParse, pTab, pWhere, iTabCur);
+    iDataCur = iIdxCur = iTabCur;
+  }
+#endif
+
+  /* Resolve the column names in the WHERE clause.
+  */
+  memset(&sNC, 0, sizeof(sNC));
+  sNC.pParse = pParse;
+  sNC.pSrcList = pTabList;
+  if( sqlite3ResolveExprNames(&sNC, pWhere) ){
+    goto delete_from_cleanup;
+  }
+
+  /* Initialize the counter of the number of rows deleted, if
+  ** we are counting rows.
+  */
+  if( db->flags & SQLITE_CountRows ){
+    memCnt = ++pParse->nMem;
+    sqlite3VdbeAddOp2(v, OP_Integer, 0, memCnt);
+  }
+
+#ifndef SQLITE_OMIT_TRUNCATE_OPTIMIZATION
+  /* Special case: A DELETE without a WHERE clause deletes everything.
+  ** It is easier just to erase the whole table. Prior to version 3.6.5,
+  ** this optimization caused the row change count (the value returned by 
+  ** API function sqlite3_count_changes) to be set incorrectly.  */
+  if( rcauth==SQLITE_OK
+   && pWhere==0
+   && !bComplex
+   && !IsVirtual(pTab)
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+   && db->xPreUpdateCallback==0
+#endif
+  ){
+    assert( !isView );
+    sqlite3TableLock(pParse, iDb, pTab->tnum, 1, pTab->zName);
+    if( HasRowid(pTab) ){
+      sqlite3VdbeAddOp4(v, OP_Clear, pTab->tnum, iDb, memCnt,
+                        pTab->zName, P4_STATIC);
+    }
+    for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+      assert( pIdx->pSchema==pTab->pSchema );
+      sqlite3VdbeAddOp2(v, OP_Clear, pIdx->tnum, iDb);
+    }
+  }else
+#endif /* SQLITE_OMIT_TRUNCATE_OPTIMIZATION */
+  {
+    u16 wcf = WHERE_ONEPASS_DESIRED|WHERE_DUPLICATES_OK|WHERE_SEEK_TABLE;
+    if( sNC.ncFlags & NC_VarSelect ) bComplex = 1;
+    wcf |= (bComplex ? 0 : WHERE_ONEPASS_MULTIROW);
+    if( HasRowid(pTab) ){
+      /* For a rowid table, initialize the RowSet to an empty set */
+      pPk = 0;
+      nPk = 1;
+      iRowSet = ++pParse->nMem;
+      sqlite3VdbeAddOp2(v, OP_Null, 0, iRowSet);
+    }else{
+      /* For a WITHOUT ROWID table, create an ephemeral table used to
+      ** hold all primary keys for rows to be deleted. */
+      pPk = sqlite3PrimaryKeyIndex(pTab);
+      assert( pPk!=0 );
+      nPk = pPk->nKeyCol;
+      iPk = pParse->nMem+1;
+      pParse->nMem += nPk;
+      iEphCur = pParse->nTab++;
+      addrEphOpen = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iEphCur, nPk);
+      sqlite3VdbeSetP4KeyInfo(pParse, pPk);
+    }
+  
+    /* Construct a query to find the rowid or primary key for every row
+    ** to be deleted, based on the WHERE clause. Set variable eOnePass
+    ** to indicate the strategy used to implement this delete:
+    **
+    **  ONEPASS_OFF:    Two-pass approach - use a FIFO for rowids/PK values.
+    **  ONEPASS_SINGLE: One-pass approach - at most one row deleted.
+    **  ONEPASS_MULTI:  One-pass approach - any number of rows may be deleted.
+    */
+    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0, 0, wcf, iTabCur+1);
+    if( pWInfo==0 ) goto delete_from_cleanup;
+    eOnePass = sqlite3WhereOkOnePass(pWInfo, aiCurOnePass);
+    assert( IsVirtual(pTab)==0 || eOnePass!=ONEPASS_MULTI );
+    assert( IsVirtual(pTab) || bComplex || eOnePass!=ONEPASS_OFF );
+  
+    /* Keep track of the number of rows to be deleted */
+    if( db->flags & SQLITE_CountRows ){
+      sqlite3VdbeAddOp2(v, OP_AddImm, memCnt, 1);
+    }
+  
+    /* Extract the rowid or primary key for the current row */
+    if( pPk ){
+      for(i=0; i<nPk; i++){
+        assert( pPk->aiColumn[i]>=0 );
+        sqlite3ExprCodeGetColumnOfTable(v, pTab, iTabCur,
+                                        pPk->aiColumn[i], iPk+i);
+      }
+      iKey = iPk;
+    }else{
+      iKey = pParse->nMem + 1;
+      iKey = sqlite3ExprCodeGetColumn(pParse, pTab, -1, iTabCur, iKey, 0);
+      if( iKey>pParse->nMem ) pParse->nMem = iKey;
+    }
+  
+    if( eOnePass!=ONEPASS_OFF ){
+      /* For ONEPASS, no need to store the rowid/primary-key. There is only
+      ** one, so just keep it in its register(s) and fall through to the
+      ** delete code.  */
+      nKey = nPk; /* OP_Found will use an unpacked key */
+      aToOpen = sqlite3DbMallocRawNN(db, nIdx+2);
+      if( aToOpen==0 ){
+        sqlite3WhereEnd(pWInfo);
+        goto delete_from_cleanup;
+      }
+      memset(aToOpen, 1, nIdx+1);
+      aToOpen[nIdx+1] = 0;
+      if( aiCurOnePass[0]>=0 ) aToOpen[aiCurOnePass[0]-iTabCur] = 0;
+      if( aiCurOnePass[1]>=0 ) aToOpen[aiCurOnePass[1]-iTabCur] = 0;
+      if( addrEphOpen ) sqlite3VdbeChangeToNoop(v, addrEphOpen);
+    }else{
+      if( pPk ){
+        /* Add the PK key for this row to the temporary table */
+        iKey = ++pParse->nMem;
+        nKey = 0;   /* Zero tells OP_Found to use a composite key */
+        sqlite3VdbeAddOp4(v, OP_MakeRecord, iPk, nPk, iKey,
+            sqlite3IndexAffinityStr(pParse->db, pPk), nPk);
+        sqlite3VdbeAddOp2(v, OP_IdxInsert, iEphCur, iKey);
+      }else{
+        /* Add the rowid of the row to be deleted to the RowSet */
+        nKey = 1;  /* OP_Seek always uses a single rowid */
+        sqlite3VdbeAddOp2(v, OP_RowSetAdd, iRowSet, iKey);
+      }
+    }
+  
+    /* If this DELETE cannot use the ONEPASS strategy, this is the 
+    ** end of the WHERE loop */
+    if( eOnePass!=ONEPASS_OFF ){
+      addrBypass = sqlite3VdbeMakeLabel(v);
+    }else{
+      sqlite3WhereEnd(pWInfo);
+    }
+  
+    /* Unless this is a view, open cursors for the table we are 
+    ** deleting from and all its indices. If this is a view, then the
+    ** only effect this statement has is to fire the INSTEAD OF 
+    ** triggers.
+    */
+    if( !isView ){
+      int iAddrOnce = 0;
+      if( eOnePass==ONEPASS_MULTI ){
+        iAddrOnce = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
+      }
+      testcase( IsVirtual(pTab) );
+      sqlite3OpenTableAndIndices(pParse, pTab, OP_OpenWrite, OPFLAG_FORDELETE,
+                                 iTabCur, aToOpen, &iDataCur, &iIdxCur);
+      assert( pPk || IsVirtual(pTab) || iDataCur==iTabCur );
+      assert( pPk || IsVirtual(pTab) || iIdxCur==iDataCur+1 );
+      if( eOnePass==ONEPASS_MULTI ) sqlite3VdbeJumpHere(v, iAddrOnce);
+    }
+  
+    /* Set up a loop over the rowids/primary-keys that were found in the
+    ** where-clause loop above.
+    */
+    if( eOnePass!=ONEPASS_OFF ){
+      assert( nKey==nPk );  /* OP_Found will use an unpacked key */
+      if( !IsVirtual(pTab) && aToOpen[iDataCur-iTabCur] ){
+        assert( pPk!=0 || pTab->pSelect!=0 );
+        sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, addrBypass, iKey, nKey);
+        VdbeCoverage(v);
+      }
+    }else if( pPk ){
+      addrLoop = sqlite3VdbeAddOp1(v, OP_Rewind, iEphCur); VdbeCoverage(v);
+      sqlite3VdbeAddOp2(v, OP_RowKey, iEphCur, iKey);
+      assert( nKey==0 );  /* OP_Found will use a composite key */
+    }else{
+      addrLoop = sqlite3VdbeAddOp3(v, OP_RowSetRead, iRowSet, 0, iKey);
+      VdbeCoverage(v);
+      assert( nKey==1 );
+    }  
+  
+    /* Delete the row */
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    if( IsVirtual(pTab) ){
+      const char *pVTab = (const char *)sqlite3GetVTable(db, pTab);
+      sqlite3VtabMakeWritable(pParse, pTab);
+      sqlite3VdbeAddOp4(v, OP_VUpdate, 0, 1, iKey, pVTab, P4_VTAB);
+      sqlite3VdbeChangeP5(v, OE_Abort);
+      assert( eOnePass==ONEPASS_OFF || eOnePass==ONEPASS_SINGLE );
+      sqlite3MayAbort(pParse);
+      if( eOnePass==ONEPASS_SINGLE && sqlite3IsToplevel(pParse) ){
+        pParse->isMultiWrite = 0;
+      }
+    }else
+#endif
+    {
+      int count = (pParse->nested==0);    /* True to count changes */
+      int iIdxNoSeek = -1;
+      if( bComplex==0 && aiCurOnePass[1]!=iDataCur ){
+        iIdxNoSeek = aiCurOnePass[1];
+      }
+      sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur,
+          iKey, nKey, count, OE_Default, eOnePass, iIdxNoSeek);
+    }
+  
+    /* End of the loop over all rowids/primary-keys. */
+    if( eOnePass!=ONEPASS_OFF ){
+      sqlite3VdbeResolveLabel(v, addrBypass);
+      sqlite3WhereEnd(pWInfo);
+    }else if( pPk ){
+      sqlite3VdbeAddOp2(v, OP_Next, iEphCur, addrLoop+1); VdbeCoverage(v);
+      sqlite3VdbeJumpHere(v, addrLoop);
+    }else{
+      sqlite3VdbeGoto(v, addrLoop);
+      sqlite3VdbeJumpHere(v, addrLoop);
+    }     
+  
+    /* Close the cursors open on the table and its indexes. */
+    if( !isView && !IsVirtual(pTab) ){
+      if( !pPk ) sqlite3VdbeAddOp1(v, OP_Close, iDataCur);
+      for(i=0, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
+        sqlite3VdbeAddOp1(v, OP_Close, iIdxCur + i);
+      }
+    }
+  } /* End non-truncate path */
+
+  /* Update the sqlite_sequence table by storing the content of the
+  ** maximum rowid counter values recorded while inserting into
+  ** autoincrement tables.
+  */
+  if( pParse->nested==0 && pParse->pTriggerTab==0 ){
+    sqlite3AutoincrementEnd(pParse);
+  }
+
+  /* Return the number of rows that were deleted. If this routine is 
+  ** generating code because of a call to sqlite3NestedParse(), do not
+  ** invoke the callback function.
+  */
+  if( (db->flags&SQLITE_CountRows) && !pParse->nested && !pParse->pTriggerTab ){
+    sqlite3VdbeAddOp2(v, OP_ResultRow, memCnt, 1);
+    sqlite3VdbeSetNumCols(v, 1);
+    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows deleted", SQLITE_STATIC);
+  }
+
+delete_from_cleanup:
+  sqlite3AuthContextPop(&sContext);
+  sqlite3SrcListDelete(db, pTabList);
+  sqlite3ExprDelete(db, pWhere);
+  sqlite3DbFree(db, aToOpen);
+  return;
+}
+/* Make sure "isView" and other macros defined above are undefined. Otherwise
+** they may interfere with compilation of other functions in this file
+** (or in another file, if this file becomes part of the amalgamation).  */
+#ifdef isView
+ #undef isView
+#endif
+#ifdef pTrigger
+ #undef pTrigger
+#endif
+
+/*
+** This routine generates VDBE code that causes a single row of a
+** single table to be deleted.  Both the original table entry and
+** all indices are removed.
+**
+** Preconditions:
+**
+**   1.  iDataCur is an open cursor on the btree that is the canonical data
+**       store for the table.  (This will be either the table itself,
+**       in the case of a rowid table, or the PRIMARY KEY index in the case
+**       of a WITHOUT ROWID table.)
+**
+**   2.  Read/write cursors for all indices of pTab must be open as
+**       cursor number iIdxCur+i for the i-th index.
+**
+**   3.  The primary key for the row to be deleted must be stored in a
+**       sequence of nPk memory cells starting at iPk.  If nPk==0 that means
+**       that a search record formed from OP_MakeRecord is contained in the
+**       single memory location iPk.
+**
+** eMode:
+**   Parameter eMode may be passed either ONEPASS_OFF (0), ONEPASS_SINGLE, or
+**   ONEPASS_MULTI.  If eMode is not ONEPASS_OFF, then the cursor
+**   iDataCur already points to the row to delete. If eMode is ONEPASS_OFF
+**   then this function must seek iDataCur to the entry identified by iPk
+**   and nPk before reading from it.
+**
+**   If eMode is ONEPASS_MULTI, then this call is being made as part
+**   of a ONEPASS delete that affects multiple rows. In this case, if 
+**   iIdxNoSeek is a valid cursor number (>=0), then its position should
+**   be preserved following the delete operation. Or, if iIdxNoSeek is not
+**   a valid cursor number, the position of iDataCur should be preserved
+**   instead.
+**
+** iIdxNoSeek:
+**   If iIdxNoSeek is a valid cursor number (>=0), then it identifies an
+**   index cursor (from within array of cursors starting at iIdxCur) that
+**   already points to the index entry to be deleted.
+*/
+SQLITE_PRIVATE void sqlite3GenerateRowDelete(
+  Parse *pParse,     /* Parsing context */
+  Table *pTab,       /* Table containing the row to be deleted */
+  Trigger *pTrigger, /* List of triggers to (potentially) fire */
+  int iDataCur,      /* Cursor from which column data is extracted */
+  int iIdxCur,       /* First index cursor */
+  int iPk,           /* First memory cell containing the PRIMARY KEY */
+  i16 nPk,           /* Number of PRIMARY KEY memory cells */
+  u8 count,          /* If non-zero, increment the row change counter */
+  u8 onconf,         /* Default ON CONFLICT policy for triggers */
+  u8 eMode,          /* ONEPASS_OFF, _SINGLE, or _MULTI.  See above */
+  int iIdxNoSeek     /* Cursor number of cursor that does not need seeking */
+){
+  Vdbe *v = pParse->pVdbe;        /* Vdbe */
+  int iOld = 0;                   /* First register in OLD.* array */
+  int iLabel;                     /* Label resolved to end of generated code */
+  u8 opSeek;                      /* Seek opcode */
+
+  /* Vdbe is guaranteed to have been allocated by this stage. */
+  assert( v );
+  VdbeModuleComment((v, "BEGIN: GenRowDel(%d,%d,%d,%d)",
+                         iDataCur, iIdxCur, iPk, (int)nPk));
+
+  /* Seek cursor iCur to the row to delete. If this row no longer exists 
+  ** (this can happen if a trigger program has already deleted it), do
+  ** not attempt to delete it or fire any DELETE triggers.  */
+  iLabel = sqlite3VdbeMakeLabel(v);
+  opSeek = HasRowid(pTab) ? OP_NotExists : OP_NotFound;
+  if( eMode==ONEPASS_OFF ){
+    sqlite3VdbeAddOp4Int(v, opSeek, iDataCur, iLabel, iPk, nPk);
+    VdbeCoverageIf(v, opSeek==OP_NotExists);
+    VdbeCoverageIf(v, opSeek==OP_NotFound);
+  }
+ 
+  /* If there are any triggers to fire, allocate a range of registers to
+  ** use for the old.* references in the triggers.  */
+  if( sqlite3FkRequired(pParse, pTab, 0, 0) || pTrigger ){
+    u32 mask;                     /* Mask of OLD.* columns in use */
+    int iCol;                     /* Iterator used while populating OLD.* */
+    int addrStart;                /* Start of BEFORE trigger programs */
+
+    /* TODO: Could use temporary registers here. Also could attempt to
+    ** avoid copying the contents of the rowid register.  */
+    mask = sqlite3TriggerColmask(
+        pParse, pTrigger, 0, 0, TRIGGER_BEFORE|TRIGGER_AFTER, pTab, onconf
+    );
+    mask |= sqlite3FkOldmask(pParse, pTab);
+    iOld = pParse->nMem+1;
+    pParse->nMem += (1 + pTab->nCol);
+
+    /* Populate the OLD.* pseudo-table register array. These values will be 
+    ** used by any BEFORE and AFTER triggers that exist.  */
+    sqlite3VdbeAddOp2(v, OP_Copy, iPk, iOld);
+    for(iCol=0; iCol<pTab->nCol; iCol++){
+      testcase( mask!=0xffffffff && iCol==31 );
+      testcase( mask!=0xffffffff && iCol==32 );
+      if( mask==0xffffffff || (iCol<=31 && (mask & MASKBIT32(iCol))!=0) ){
+        sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, iCol, iOld+iCol+1);
+      }
+    }
+
+    /* Invoke BEFORE DELETE trigger programs. */
+    addrStart = sqlite3VdbeCurrentAddr(v);
+    sqlite3CodeRowTrigger(pParse, pTrigger, 
+        TK_DELETE, 0, TRIGGER_BEFORE, pTab, iOld, onconf, iLabel
+    );
+
+    /* If any BEFORE triggers were coded, then seek the cursor to the 
+    ** row to be deleted again. It may be that the BEFORE triggers moved
+    ** the cursor or of already deleted the row that the cursor was
+    ** pointing to.
+    */
+    if( addrStart<sqlite3VdbeCurrentAddr(v) ){
+      sqlite3VdbeAddOp4Int(v, opSeek, iDataCur, iLabel, iPk, nPk);
+      VdbeCoverageIf(v, opSeek==OP_NotExists);
+      VdbeCoverageIf(v, opSeek==OP_NotFound);
+    }
+
+    /* Do FK processing. This call checks that any FK constraints that
+    ** refer to this table (i.e. constraints attached to other tables) 
+    ** are not violated by deleting this row.  */
+    sqlite3FkCheck(pParse, pTab, iOld, 0, 0, 0);
+  }
+
+  /* Delete the index and table entries. Skip this step if pTab is really
+  ** a view (in which case the only effect of the DELETE statement is to
+  ** fire the INSTEAD OF triggers).  
+  **
+  ** If variable 'count' is non-zero, then this OP_Delete instruction should
+  ** invoke the update-hook. The pre-update-hook, on the other hand should
+  ** be invoked unless table pTab is a system table. The difference is that
+  ** the update-hook is not invoked for rows removed by REPLACE, but the 
+  ** pre-update-hook is.
+  */ 
+  if( pTab->pSelect==0 ){
+    u8 p5 = 0;
+    sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur,0,iIdxNoSeek);
+    sqlite3VdbeAddOp2(v, OP_Delete, iDataCur, (count?OPFLAG_NCHANGE:0));
+    sqlite3VdbeChangeP4(v, -1, (char*)pTab, P4_TABLE);
+    if( eMode!=ONEPASS_OFF ){
+      sqlite3VdbeChangeP5(v, OPFLAG_AUXDELETE);
+    }
+    if( iIdxNoSeek>=0 ){
+      sqlite3VdbeAddOp1(v, OP_Delete, iIdxNoSeek);
+    }
+    if( eMode==ONEPASS_MULTI ) p5 |= OPFLAG_SAVEPOSITION;
+    sqlite3VdbeChangeP5(v, p5);
+  }
+
+  /* Do any ON CASCADE, SET NULL or SET DEFAULT operations required to
+  ** handle rows (possibly in other tables) that refer via a foreign key
+  ** to the row just deleted. */ 
+  sqlite3FkActions(pParse, pTab, 0, iOld, 0, 0);
+
+  /* Invoke AFTER DELETE trigger programs. */
+  sqlite3CodeRowTrigger(pParse, pTrigger, 
+      TK_DELETE, 0, TRIGGER_AFTER, pTab, iOld, onconf, iLabel
+  );
+
+  /* Jump here if the row had already been deleted before any BEFORE
+  ** trigger programs were invoked. Or if a trigger program throws a 
+  ** RAISE(IGNORE) exception.  */
+  sqlite3VdbeResolveLabel(v, iLabel);
+  VdbeModuleComment((v, "END: GenRowDel()"));
+}
+
+/*
+** This routine generates VDBE code that causes the deletion of all
+** index entries associated with a single row of a single table, pTab
+**
+** Preconditions:
+**
+**   1.  A read/write cursor "iDataCur" must be open on the canonical storage
+**       btree for the table pTab.  (This will be either the table itself
+**       for rowid tables or to the primary key index for WITHOUT ROWID
+**       tables.)
+**
+**   2.  Read/write cursors for all indices of pTab must be open as
+**       cursor number iIdxCur+i for the i-th index.  (The pTab->pIndex
+**       index is the 0-th index.)
+**
+**   3.  The "iDataCur" cursor must be already be positioned on the row
+**       that is to be deleted.
+*/
+SQLITE_PRIVATE void sqlite3GenerateRowIndexDelete(
+  Parse *pParse,     /* Parsing and code generating context */
+  Table *pTab,       /* Table containing the row to be deleted */
+  int iDataCur,      /* Cursor of table holding data. */
+  int iIdxCur,       /* First index cursor */
+  int *aRegIdx,      /* Only delete if aRegIdx!=0 && aRegIdx[i]>0 */
+  int iIdxNoSeek     /* Do not delete from this cursor */
+){
+  int i;             /* Index loop counter */
+  int r1 = -1;       /* Register holding an index key */
+  int iPartIdxLabel; /* Jump destination for skipping partial index entries */
+  Index *pIdx;       /* Current index */
+  Index *pPrior = 0; /* Prior index */
+  Vdbe *v;           /* The prepared statement under construction */
+  Index *pPk;        /* PRIMARY KEY index, or NULL for rowid tables */
+
+  v = pParse->pVdbe;
+  pPk = HasRowid(pTab) ? 0 : sqlite3PrimaryKeyIndex(pTab);
+  for(i=0, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
+    assert( iIdxCur+i!=iDataCur || pPk==pIdx );
+    if( aRegIdx!=0 && aRegIdx[i]==0 ) continue;
+    if( pIdx==pPk ) continue;
+    if( iIdxCur+i==iIdxNoSeek ) continue;
+    VdbeModuleComment((v, "GenRowIdxDel for %s", pIdx->zName));
+    r1 = sqlite3GenerateIndexKey(pParse, pIdx, iDataCur, 0, 1,
+        &iPartIdxLabel, pPrior, r1);
+    sqlite3VdbeAddOp3(v, OP_IdxDelete, iIdxCur+i, r1,
+        pIdx->uniqNotNull ? pIdx->nKeyCol : pIdx->nColumn);
+    sqlite3ResolvePartIdxLabel(pParse, iPartIdxLabel);
+    pPrior = pIdx;
+  }
+}
+
+/*
+** Generate code that will assemble an index key and stores it in register
+** regOut.  The key with be for index pIdx which is an index on pTab.
+** iCur is the index of a cursor open on the pTab table and pointing to
+** the entry that needs indexing.  If pTab is a WITHOUT ROWID table, then
+** iCur must be the cursor of the PRIMARY KEY index.
+**
+** Return a register number which is the first in a block of
+** registers that holds the elements of the index key.  The
+** block of registers has already been deallocated by the time
+** this routine returns.
+**
+** If *piPartIdxLabel is not NULL, fill it in with a label and jump
+** to that label if pIdx is a partial index that should be skipped.
+** The label should be resolved using sqlite3ResolvePartIdxLabel().
+** A partial index should be skipped if its WHERE clause evaluates
+** to false or null.  If pIdx is not a partial index, *piPartIdxLabel
+** will be set to zero which is an empty label that is ignored by
+** sqlite3ResolvePartIdxLabel().
+**
+** The pPrior and regPrior parameters are used to implement a cache to
+** avoid unnecessary register loads.  If pPrior is not NULL, then it is
+** a pointer to a different index for which an index key has just been
+** computed into register regPrior.  If the current pIdx index is generating
+** its key into the same sequence of registers and if pPrior and pIdx share
+** a column in common, then the register corresponding to that column already
+** holds the correct value and the loading of that register is skipped.
+** This optimization is helpful when doing a DELETE or an INTEGRITY_CHECK 
+** on a table with multiple indices, and especially with the ROWID or
+** PRIMARY KEY columns of the index.
+*/
+SQLITE_PRIVATE int sqlite3GenerateIndexKey(
+  Parse *pParse,       /* Parsing context */
+  Index *pIdx,         /* The index for which to generate a key */
+  int iDataCur,        /* Cursor number from which to take column data */
+  int regOut,          /* Put the new key into this register if not 0 */
+  int prefixOnly,      /* Compute only a unique prefix of the key */
+  int *piPartIdxLabel, /* OUT: Jump to this label to skip partial index */
+  Index *pPrior,       /* Previously generated index key */
+  int regPrior         /* Register holding previous generated key */
+){
+  Vdbe *v = pParse->pVdbe;
+  int j;
+  int regBase;
+  int nCol;
+
+  if( piPartIdxLabel ){
+    if( pIdx->pPartIdxWhere ){
+      *piPartIdxLabel = sqlite3VdbeMakeLabel(v);
+      pParse->iSelfTab = iDataCur;
+      sqlite3ExprCachePush(pParse);
+      sqlite3ExprIfFalseDup(pParse, pIdx->pPartIdxWhere, *piPartIdxLabel, 
+                            SQLITE_JUMPIFNULL);
+    }else{
+      *piPartIdxLabel = 0;
+    }
+  }
+  nCol = (prefixOnly && pIdx->uniqNotNull) ? pIdx->nKeyCol : pIdx->nColumn;
+  regBase = sqlite3GetTempRange(pParse, nCol);
+  if( pPrior && (regBase!=regPrior || pPrior->pPartIdxWhere) ) pPrior = 0;
+  for(j=0; j<nCol; j++){
+    if( pPrior
+     && pPrior->aiColumn[j]==pIdx->aiColumn[j]
+     && pPrior->aiColumn[j]!=XN_EXPR
+    ){
+      /* This column was already computed by the previous index */
+      continue;
+    }
+    sqlite3ExprCodeLoadIndexColumn(pParse, pIdx, iDataCur, j, regBase+j);
+    /* If the column affinity is REAL but the number is an integer, then it
+    ** might be stored in the table as an integer (using a compact
+    ** representation) then converted to REAL by an OP_RealAffinity opcode.
+    ** But we are getting ready to store this value back into an index, where
+    ** it should be converted by to INTEGER again.  So omit the OP_RealAffinity
+    ** opcode if it is present */
+    sqlite3VdbeDeletePriorOpcode(v, OP_RealAffinity);
+  }
+  if( regOut ){
+    sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol, regOut);
+  }
+  sqlite3ReleaseTempRange(pParse, regBase, nCol);
+  return regBase;
+}
+
+/*
+** If a prior call to sqlite3GenerateIndexKey() generated a jump-over label
+** because it was a partial index, then this routine should be called to
+** resolve that label.
+*/
+SQLITE_PRIVATE void sqlite3ResolvePartIdxLabel(Parse *pParse, int iLabel){
+  if( iLabel ){
+    sqlite3VdbeResolveLabel(pParse->pVdbe, iLabel);
+    sqlite3ExprCachePop(pParse);
+  }
+}
+
+/************** End of delete.c **********************************************/
+/************** Begin file func.c ********************************************/
+/*
+** 2002 February 23
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C-language implementations for many of the SQL
+** functions of SQLite.  (Some function, and in particular the date and
+** time functions, are implemented separately.)
+*/
+/* #include "sqliteInt.h" */
+/* #include <stdlib.h> */
+/* #include <assert.h> */
+/* #include "vdbeInt.h" */
+
+/*
+** Return the collating function associated with a function.
+*/
+static CollSeq *sqlite3GetFuncCollSeq(sqlite3_context *context){
+  VdbeOp *pOp;
+  assert( context->pVdbe!=0 );
+  pOp = &context->pVdbe->aOp[context->iOp-1];
+  assert( pOp->opcode==OP_CollSeq );
+  assert( pOp->p4type==P4_COLLSEQ );
+  return pOp->p4.pColl;
+}
+
+/*
+** Indicate that the accumulator load should be skipped on this
+** iteration of the aggregate loop.
+*/
+static void sqlite3SkipAccumulatorLoad(sqlite3_context *context){
+  context->skipFlag = 1;
+}
+
+/*
+** Implementation of the non-aggregate min() and max() functions
+*/
+static void minmaxFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  int i;
+  int mask;    /* 0 for min() or 0xffffffff for max() */
+  int iBest;
+  CollSeq *pColl;
+
+  assert( argc>1 );
+  mask = sqlite3_user_data(context)==0 ? 0 : -1;
+  pColl = sqlite3GetFuncCollSeq(context);
+  assert( pColl );
+  assert( mask==-1 || mask==0 );
+  iBest = 0;
+  if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
+  for(i=1; i<argc; i++){
+    if( sqlite3_value_type(argv[i])==SQLITE_NULL ) return;
+    if( (sqlite3MemCompare(argv[iBest], argv[i], pColl)^mask)>=0 ){
+      testcase( mask==0 );
+      iBest = i;
+    }
+  }
+  sqlite3_result_value(context, argv[iBest]);
+}
+
+/*
+** Return the type of the argument.
+*/
+static void typeofFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **argv
+){
+  const char *z = 0;
+  UNUSED_PARAMETER(NotUsed);
+  switch( sqlite3_value_type(argv[0]) ){
+    case SQLITE_INTEGER: z = "integer"; break;
+    case SQLITE_TEXT:    z = "text";    break;
+    case SQLITE_FLOAT:   z = "real";    break;
+    case SQLITE_BLOB:    z = "blob";    break;
+    default:             z = "null";    break;
+  }
+  sqlite3_result_text(context, z, -1, SQLITE_STATIC);
+}
+
+
+/*
+** Implementation of the length() function
+*/
+static void lengthFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  int len;
+
+  assert( argc==1 );
+  UNUSED_PARAMETER(argc);
+  switch( sqlite3_value_type(argv[0]) ){
+    case SQLITE_BLOB:
+    case SQLITE_INTEGER:
+    case SQLITE_FLOAT: {
+      sqlite3_result_int(context, sqlite3_value_bytes(argv[0]));
+      break;
+    }
+    case SQLITE_TEXT: {
+      const unsigned char *z = sqlite3_value_text(argv[0]);
+      if( z==0 ) return;
+      len = 0;
+      while( *z ){
+        len++;
+        SQLITE_SKIP_UTF8(z);
+      }
+      sqlite3_result_int(context, len);
+      break;
+    }
+    default: {
+      sqlite3_result_null(context);
+      break;
+    }
+  }
+}
+
+/*
+** Implementation of the abs() function.
+**
+** IMP: R-23979-26855 The abs(X) function returns the absolute value of
+** the numeric argument X. 
+*/
+static void absFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
+  assert( argc==1 );
+  UNUSED_PARAMETER(argc);
+  switch( sqlite3_value_type(argv[0]) ){
+    case SQLITE_INTEGER: {
+      i64 iVal = sqlite3_value_int64(argv[0]);
+      if( iVal<0 ){
+        if( iVal==SMALLEST_INT64 ){
+          /* IMP: R-31676-45509 If X is the integer -9223372036854775808
+          ** then abs(X) throws an integer overflow error since there is no
+          ** equivalent positive 64-bit two complement value. */
+          sqlite3_result_error(context, "integer overflow", -1);
+          return;
+        }
+        iVal = -iVal;
+      } 
+      sqlite3_result_int64(context, iVal);
+      break;
+    }
+    case SQLITE_NULL: {
+      /* IMP: R-37434-19929 Abs(X) returns NULL if X is NULL. */
+      sqlite3_result_null(context);
+      break;
+    }
+    default: {
+      /* Because sqlite3_value_double() returns 0.0 if the argument is not
+      ** something that can be converted into a number, we have:
+      ** IMP: R-01992-00519 Abs(X) returns 0.0 if X is a string or blob
+      ** that cannot be converted to a numeric value.
+      */
+      double rVal = sqlite3_value_double(argv[0]);
+      if( rVal<0 ) rVal = -rVal;
+      sqlite3_result_double(context, rVal);
+      break;
+    }
+  }
+}
+
+/*
+** Implementation of the instr() function.
+**
+** instr(haystack,needle) finds the first occurrence of needle
+** in haystack and returns the number of previous characters plus 1,
+** or 0 if needle does not occur within haystack.
+**
+** If both haystack and needle are BLOBs, then the result is one more than
+** the number of bytes in haystack prior to the first occurrence of needle,
+** or 0 if needle never occurs in haystack.
+*/
+static void instrFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  const unsigned char *zHaystack;
+  const unsigned char *zNeedle;
+  int nHaystack;
+  int nNeedle;
+  int typeHaystack, typeNeedle;
+  int N = 1;
+  int isText;
+
+  UNUSED_PARAMETER(argc);
+  typeHaystack = sqlite3_value_type(argv[0]);
+  typeNeedle = sqlite3_value_type(argv[1]);
+  if( typeHaystack==SQLITE_NULL || typeNeedle==SQLITE_NULL ) return;
+  nHaystack = sqlite3_value_bytes(argv[0]);
+  nNeedle = sqlite3_value_bytes(argv[1]);
+  if( typeHaystack==SQLITE_BLOB && typeNeedle==SQLITE_BLOB ){
+    zHaystack = sqlite3_value_blob(argv[0]);
+    zNeedle = sqlite3_value_blob(argv[1]);
+    isText = 0;
+  }else{
+    zHaystack = sqlite3_value_text(argv[0]);
+    zNeedle = sqlite3_value_text(argv[1]);
+    isText = 1;
+    if( zNeedle==0 ) return;
+    assert( zHaystack );
+  }
+  while( nNeedle<=nHaystack && memcmp(zHaystack, zNeedle, nNeedle)!=0 ){
+    N++;
+    do{
+      nHaystack--;
+      zHaystack++;
+    }while( isText && (zHaystack[0]&0xc0)==0x80 );
+  }
+  if( nNeedle>nHaystack ) N = 0;
+  sqlite3_result_int(context, N);
+}
+
+/*
+** Implementation of the printf() function.
+*/
+static void printfFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  PrintfArguments x;
+  StrAccum str;
+  const char *zFormat;
+  int n;
+  sqlite3 *db = sqlite3_context_db_handle(context);
+
+  if( argc>=1 && (zFormat = (const char*)sqlite3_value_text(argv[0]))!=0 ){
+    x.nArg = argc-1;
+    x.nUsed = 0;
+    x.apArg = argv+1;
+    sqlite3StrAccumInit(&str, db, 0, 0, db->aLimit[SQLITE_LIMIT_LENGTH]);
+    str.printfFlags = SQLITE_PRINTF_SQLFUNC;
+    sqlite3XPrintf(&str, zFormat, &x);
+    n = str.nChar;
+    sqlite3_result_text(context, sqlite3StrAccumFinish(&str), n,
+                        SQLITE_DYNAMIC);
+  }
+}
+
+/*
+** Implementation of the substr() function.
+**
+** substr(x,p1,p2)  returns p2 characters of x[] beginning with p1.
+** p1 is 1-indexed.  So substr(x,1,1) returns the first character
+** of x.  If x is text, then we actually count UTF-8 characters.
+** If x is a blob, then we count bytes.
+**
+** If p1 is negative, then we begin abs(p1) from the end of x[].
+**
+** If p2 is negative, return the p2 characters preceding p1.
+*/
+static void substrFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  const unsigned char *z;
+  const unsigned char *z2;
+  int len;
+  int p0type;
+  i64 p1, p2;
+  int negP2 = 0;
+
+  assert( argc==3 || argc==2 );
+  if( sqlite3_value_type(argv[1])==SQLITE_NULL
+   || (argc==3 && sqlite3_value_type(argv[2])==SQLITE_NULL)
+  ){
+    return;
+  }
+  p0type = sqlite3_value_type(argv[0]);
+  p1 = sqlite3_value_int(argv[1]);
+  if( p0type==SQLITE_BLOB ){
+    len = sqlite3_value_bytes(argv[0]);
+    z = sqlite3_value_blob(argv[0]);
+    if( z==0 ) return;
+    assert( len==sqlite3_value_bytes(argv[0]) );
+  }else{
+    z = sqlite3_value_text(argv[0]);
+    if( z==0 ) return;
+    len = 0;
+    if( p1<0 ){
+      for(z2=z; *z2; len++){
+        SQLITE_SKIP_UTF8(z2);
+      }
+    }
+  }
+#ifdef SQLITE_SUBSTR_COMPATIBILITY
+  /* If SUBSTR_COMPATIBILITY is defined then substr(X,0,N) work the same as
+  ** as substr(X,1,N) - it returns the first N characters of X.  This
+  ** is essentially a back-out of the bug-fix in check-in [5fc125d362df4b8]
+  ** from 2009-02-02 for compatibility of applications that exploited the
+  ** old buggy behavior. */
+  if( p1==0 ) p1 = 1; /* <rdar://problem/6778339> */
+#endif
+  if( argc==3 ){
+    p2 = sqlite3_value_int(argv[2]);
+    if( p2<0 ){
+      p2 = -p2;
+      negP2 = 1;
+    }
+  }else{
+    p2 = sqlite3_context_db_handle(context)->aLimit[SQLITE_LIMIT_LENGTH];
+  }
+  if( p1<0 ){
+    p1 += len;
+    if( p1<0 ){
+      p2 += p1;
+      if( p2<0 ) p2 = 0;
+      p1 = 0;
+    }
+  }else if( p1>0 ){
+    p1--;
+  }else if( p2>0 ){
+    p2--;
+  }
+  if( negP2 ){
+    p1 -= p2;
+    if( p1<0 ){
+      p2 += p1;
+      p1 = 0;
+    }
+  }
+  assert( p1>=0 && p2>=0 );
+  if( p0type!=SQLITE_BLOB ){
+    while( *z && p1 ){
+      SQLITE_SKIP_UTF8(z);
+      p1--;
+    }
+    for(z2=z; *z2 && p2; p2--){
+      SQLITE_SKIP_UTF8(z2);
+    }
+    sqlite3_result_text64(context, (char*)z, z2-z, SQLITE_TRANSIENT,
+                          SQLITE_UTF8);
+  }else{
+    if( p1+p2>len ){
+      p2 = len-p1;
+      if( p2<0 ) p2 = 0;
+    }
+    sqlite3_result_blob64(context, (char*)&z[p1], (u64)p2, SQLITE_TRANSIENT);
+  }
+}
+
+/*
+** Implementation of the round() function
+*/
+#ifndef SQLITE_OMIT_FLOATING_POINT
+static void roundFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
+  int n = 0;
+  double r;
+  char *zBuf;
+  assert( argc==1 || argc==2 );
+  if( argc==2 ){
+    if( SQLITE_NULL==sqlite3_value_type(argv[1]) ) return;
+    n = sqlite3_value_int(argv[1]);
+    if( n>30 ) n = 30;
+    if( n<0 ) n = 0;
+  }
+  if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
+  r = sqlite3_value_double(argv[0]);
+  /* If Y==0 and X will fit in a 64-bit int,
+  ** handle the rounding directly,
+  ** otherwise use printf.
+  */
+  if( n==0 && r>=0 && r<LARGEST_INT64-1 ){
+    r = (double)((sqlite_int64)(r+0.5));
+  }else if( n==0 && r<0 && (-r)<LARGEST_INT64-1 ){
+    r = -(double)((sqlite_int64)((-r)+0.5));
+  }else{
+    zBuf = sqlite3_mprintf("%.*f",n,r);
+    if( zBuf==0 ){
+      sqlite3_result_error_nomem(context);
+      return;
+    }
+    sqlite3AtoF(zBuf, &r, sqlite3Strlen30(zBuf), SQLITE_UTF8);
+    sqlite3_free(zBuf);
+  }
+  sqlite3_result_double(context, r);
+}
+#endif
+
+/*
+** Allocate nByte bytes of space using sqlite3Malloc(). If the
+** allocation fails, call sqlite3_result_error_nomem() to notify
+** the database handle that malloc() has failed and return NULL.
+** If nByte is larger than the maximum string or blob length, then
+** raise an SQLITE_TOOBIG exception and return NULL.
+*/
+static void *contextMalloc(sqlite3_context *context, i64 nByte){
+  char *z;
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  assert( nByte>0 );
+  testcase( nByte==db->aLimit[SQLITE_LIMIT_LENGTH] );
+  testcase( nByte==db->aLimit[SQLITE_LIMIT_LENGTH]+1 );
+  if( nByte>db->aLimit[SQLITE_LIMIT_LENGTH] ){
+    sqlite3_result_error_toobig(context);
+    z = 0;
+  }else{
+    z = sqlite3Malloc(nByte);
+    if( !z ){
+      sqlite3_result_error_nomem(context);
+    }
+  }
+  return z;
+}
+
+/*
+** Implementation of the upper() and lower() SQL functions.
+*/
+static void upperFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
+  char *z1;
+  const char *z2;
+  int i, n;
+  UNUSED_PARAMETER(argc);
+  z2 = (char*)sqlite3_value_text(argv[0]);
+  n = sqlite3_value_bytes(argv[0]);
+  /* Verify that the call to _bytes() does not invalidate the _text() pointer */
+  assert( z2==(char*)sqlite3_value_text(argv[0]) );
+  if( z2 ){
+    z1 = contextMalloc(context, ((i64)n)+1);
+    if( z1 ){
+      for(i=0; i<n; i++){
+        z1[i] = (char)sqlite3Toupper(z2[i]);
+      }
+      sqlite3_result_text(context, z1, n, sqlite3_free);
+    }
+  }
+}
+static void lowerFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
+  char *z1;
+  const char *z2;
+  int i, n;
+  UNUSED_PARAMETER(argc);
+  z2 = (char*)sqlite3_value_text(argv[0]);
+  n = sqlite3_value_bytes(argv[0]);
+  /* Verify that the call to _bytes() does not invalidate the _text() pointer */
+  assert( z2==(char*)sqlite3_value_text(argv[0]) );
+  if( z2 ){
+    z1 = contextMalloc(context, ((i64)n)+1);
+    if( z1 ){
+      for(i=0; i<n; i++){
+        z1[i] = sqlite3Tolower(z2[i]);
+      }
+      sqlite3_result_text(context, z1, n, sqlite3_free);
+    }
+  }
+}
+
+/*
+** Some functions like COALESCE() and IFNULL() and UNLIKELY() are implemented
+** as VDBE code so that unused argument values do not have to be computed.
+** However, we still need some kind of function implementation for this
+** routines in the function table.  The noopFunc macro provides this.
+** noopFunc will never be called so it doesn't matter what the implementation
+** is.  We might as well use the "version()" function as a substitute.
+*/
+#define noopFunc versionFunc   /* Substitute function - never called */
+
+/*
+** Implementation of random().  Return a random integer.  
+*/
+static void randomFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **NotUsed2
+){
+  sqlite_int64 r;
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  sqlite3_randomness(sizeof(r), &r);
+  if( r<0 ){
+    /* We need to prevent a random number of 0x8000000000000000 
+    ** (or -9223372036854775808) since when you do abs() of that
+    ** number of you get the same value back again.  To do this
+    ** in a way that is testable, mask the sign bit off of negative
+    ** values, resulting in a positive value.  Then take the 
+    ** 2s complement of that positive value.  The end result can
+    ** therefore be no less than -9223372036854775807.
+    */
+    r = -(r & LARGEST_INT64);
+  }
+  sqlite3_result_int64(context, r);
+}
+
+/*
+** Implementation of randomblob(N).  Return a random blob
+** that is N bytes long.
+*/
+static void randomBlob(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  int n;
+  unsigned char *p;
+  assert( argc==1 );
+  UNUSED_PARAMETER(argc);
+  n = sqlite3_value_int(argv[0]);
+  if( n<1 ){
+    n = 1;
+  }
+  p = contextMalloc(context, n);
+  if( p ){
+    sqlite3_randomness(n, p);
+    sqlite3_result_blob(context, (char*)p, n, sqlite3_free);
+  }
+}
+
+/*
+** Implementation of the last_insert_rowid() SQL function.  The return
+** value is the same as the sqlite3_last_insert_rowid() API function.
+*/
+static void last_insert_rowid(
+  sqlite3_context *context, 
+  int NotUsed, 
+  sqlite3_value **NotUsed2
+){
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  /* IMP: R-51513-12026 The last_insert_rowid() SQL function is a
+  ** wrapper around the sqlite3_last_insert_rowid() C/C++ interface
+  ** function. */
+  sqlite3_result_int64(context, sqlite3_last_insert_rowid(db));
+}
+
+/*
+** Implementation of the changes() SQL function.
+**
+** IMP: R-62073-11209 The changes() SQL function is a wrapper
+** around the sqlite3_changes() C/C++ function and hence follows the same
+** rules for counting changes.
+*/
+static void changes(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **NotUsed2
+){
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  sqlite3_result_int(context, sqlite3_changes(db));
+}
+
+/*
+** Implementation of the total_changes() SQL function.  The return value is
+** the same as the sqlite3_total_changes() API function.
+*/
+static void total_changes(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **NotUsed2
+){
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  /* IMP: R-52756-41993 This function is a wrapper around the
+  ** sqlite3_total_changes() C/C++ interface. */
+  sqlite3_result_int(context, sqlite3_total_changes(db));
+}
+
+/*
+** A structure defining how to do GLOB-style comparisons.
+*/
+struct compareInfo {
+  u8 matchAll;          /* "*" or "%" */
+  u8 matchOne;          /* "?" or "_" */
+  u8 matchSet;          /* "[" or 0 */
+  u8 noCase;            /* true to ignore case differences */
+};
+
+/*
+** For LIKE and GLOB matching on EBCDIC machines, assume that every
+** character is exactly one byte in size.  Also, provde the Utf8Read()
+** macro for fast reading of the next character in the common case where
+** the next character is ASCII.
+*/
+#if defined(SQLITE_EBCDIC)
+# define sqlite3Utf8Read(A)        (*((*A)++))
+# define Utf8Read(A)               (*(A++))
+#else
+# define Utf8Read(A)               (A[0]<0x80?*(A++):sqlite3Utf8Read(&A))
+#endif
+
+static const struct compareInfo globInfo = { '*', '?', '[', 0 };
+/* The correct SQL-92 behavior is for the LIKE operator to ignore
+** case.  Thus  'a' LIKE 'A' would be true. */
+static const struct compareInfo likeInfoNorm = { '%', '_',   0, 1 };
+/* If SQLITE_CASE_SENSITIVE_LIKE is defined, then the LIKE operator
+** is case sensitive causing 'a' LIKE 'A' to be false */
+static const struct compareInfo likeInfoAlt = { '%', '_',   0, 0 };
+
+/*
+** Compare two UTF-8 strings for equality where the first string can
+** potentially be a "glob" or "like" expression.  Return true (1) if they
+** are the same and false (0) if they are different.
+**
+** Globbing rules:
+**
+**      '*'       Matches any sequence of zero or more characters.
+**
+**      '?'       Matches exactly one character.
+**
+**     [...]      Matches one character from the enclosed list of
+**                characters.
+**
+**     [^...]     Matches one character not in the enclosed list.
+**
+** With the [...] and [^...] matching, a ']' character can be included
+** in the list by making it the first character after '[' or '^'.  A
+** range of characters can be specified using '-'.  Example:
+** "[a-z]" matches any single lower-case letter.  To match a '-', make
+** it the last character in the list.
+**
+** Like matching rules:
+** 
+**      '%'       Matches any sequence of zero or more characters
+**
+***     '_'       Matches any one character
+**
+**      Ec        Where E is the "esc" character and c is any other
+**                character, including '%', '_', and esc, match exactly c.
+**
+** The comments within this routine usually assume glob matching.
+**
+** This routine is usually quick, but can be N**2 in the worst case.
+*/
+static int patternCompare(
+  const u8 *zPattern,              /* The glob pattern */
+  const u8 *zString,               /* The string to compare against the glob */
+  const struct compareInfo *pInfo, /* Information about how to do the compare */
+  u32 matchOther                   /* The escape char (LIKE) or '[' (GLOB) */
+){
+  u32 c, c2;                       /* Next pattern and input string chars */
+  u32 matchOne = pInfo->matchOne;  /* "?" or "_" */
+  u32 matchAll = pInfo->matchAll;  /* "*" or "%" */
+  u8 noCase = pInfo->noCase;       /* True if uppercase==lowercase */
+  const u8 *zEscaped = 0;          /* One past the last escaped input char */
+  
+  while( (c = Utf8Read(zPattern))!=0 ){
+    if( c==matchAll ){  /* Match "*" */
+      /* Skip over multiple "*" characters in the pattern.  If there
+      ** are also "?" characters, skip those as well, but consume a
+      ** single character of the input string for each "?" skipped */
+      while( (c=Utf8Read(zPattern)) == matchAll || c == matchOne ){
+        if( c==matchOne && sqlite3Utf8Read(&zString)==0 ){
+          return 0;
+        }
+      }
+      if( c==0 ){
+        return 1;   /* "*" at the end of the pattern matches */
+      }else if( c==matchOther ){
+        if( pInfo->matchSet==0 ){
+          c = sqlite3Utf8Read(&zPattern);
+          if( c==0 ) return 0;
+        }else{
+          /* "[...]" immediately follows the "*".  We have to do a slow
+          ** recursive search in this case, but it is an unusual case. */
+          assert( matchOther<0x80 );  /* '[' is a single-byte character */
+          while( *zString
+                 && patternCompare(&zPattern[-1],zString,pInfo,matchOther)==0 ){
+            SQLITE_SKIP_UTF8(zString);
+          }
+          return *zString!=0;
+        }
+      }
+
+      /* At this point variable c contains the first character of the
+      ** pattern string past the "*".  Search in the input string for the
+      ** first matching character and recursively contine the match from
+      ** that point.
+      **
+      ** For a case-insensitive search, set variable cx to be the same as
+      ** c but in the other case and search the input string for either
+      ** c or cx.
+      */
+      if( c<=0x80 ){
+        u32 cx;
+        if( noCase ){
+          cx = sqlite3Toupper(c);
+          c = sqlite3Tolower(c);
+        }else{
+          cx = c;
+        }
+        while( (c2 = *(zString++))!=0 ){
+          if( c2!=c && c2!=cx ) continue;
+          if( patternCompare(zPattern,zString,pInfo,matchOther) ) return 1;
+        }
+      }else{
+        while( (c2 = Utf8Read(zString))!=0 ){
+          if( c2!=c ) continue;
+          if( patternCompare(zPattern,zString,pInfo,matchOther) ) return 1;
+        }
+      }
+      return 0;
+    }
+    if( c==matchOther ){
+      if( pInfo->matchSet==0 ){
+        c = sqlite3Utf8Read(&zPattern);
+        if( c==0 ) return 0;
+        zEscaped = zPattern;
+      }else{
+        u32 prior_c = 0;
+        int seen = 0;
+        int invert = 0;
+        c = sqlite3Utf8Read(&zString);
+        if( c==0 ) return 0;
+        c2 = sqlite3Utf8Read(&zPattern);
+        if( c2=='^' ){
+          invert = 1;
+          c2 = sqlite3Utf8Read(&zPattern);
+        }
+        if( c2==']' ){
+          if( c==']' ) seen = 1;
+          c2 = sqlite3Utf8Read(&zPattern);
+        }
+        while( c2 && c2!=']' ){
+          if( c2=='-' && zPattern[0]!=']' && zPattern[0]!=0 && prior_c>0 ){
+            c2 = sqlite3Utf8Read(&zPattern);
+            if( c>=prior_c && c<=c2 ) seen = 1;
+            prior_c = 0;
+          }else{
+            if( c==c2 ){
+              seen = 1;
+            }
+            prior_c = c2;
+          }
+          c2 = sqlite3Utf8Read(&zPattern);
+        }
+        if( c2==0 || (seen ^ invert)==0 ){
+          return 0;
+        }
+        continue;
+      }
+    }
+    c2 = Utf8Read(zString);
+    if( c==c2 ) continue;
+    if( noCase  && sqlite3Tolower(c)==sqlite3Tolower(c2) && c<0x80 && c2<0x80 ){
+      continue;
+    }
+    if( c==matchOne && zPattern!=zEscaped && c2!=0 ) continue;
+    return 0;
+  }
+  return *zString==0;
+}
+
+/*
+** The sqlite3_strglob() interface.
+*/
+SQLITE_API int sqlite3_strglob(const char *zGlobPattern, const char *zString){
+  return patternCompare((u8*)zGlobPattern, (u8*)zString, &globInfo, '[')==0;
+}
+
+/*
+** The sqlite3_strlike() interface.
+*/
+SQLITE_API int sqlite3_strlike(const char *zPattern, const char *zStr, unsigned int esc){
+  return patternCompare((u8*)zPattern, (u8*)zStr, &likeInfoNorm, esc)==0;
+}
+
+/*
+** Count the number of times that the LIKE operator (or GLOB which is
+** just a variation of LIKE) gets called.  This is used for testing
+** only.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_like_count = 0;
+#endif
+
+
+/*
+** Implementation of the like() SQL function.  This function implements
+** the build-in LIKE operator.  The first argument to the function is the
+** pattern and the second argument is the string.  So, the SQL statements:
+**
+**       A LIKE B
+**
+** is implemented as like(B,A).
+**
+** This same function (with a different compareInfo structure) computes
+** the GLOB operator.
+*/
+static void likeFunc(
+  sqlite3_context *context, 
+  int argc, 
+  sqlite3_value **argv
+){
+  const unsigned char *zA, *zB;
+  u32 escape;
+  int nPat;
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  struct compareInfo *pInfo = sqlite3_user_data(context);
+
+#ifdef SQLITE_LIKE_DOESNT_MATCH_BLOBS
+  if( sqlite3_value_type(argv[0])==SQLITE_BLOB
+   || sqlite3_value_type(argv[1])==SQLITE_BLOB
+  ){
+#ifdef SQLITE_TEST
+    sqlite3_like_count++;
+#endif
+    sqlite3_result_int(context, 0);
+    return;
+  }
+#endif
+  zB = sqlite3_value_text(argv[0]);
+  zA = sqlite3_value_text(argv[1]);
+
+  /* Limit the length of the LIKE or GLOB pattern to avoid problems
+  ** of deep recursion and N*N behavior in patternCompare().
+  */
+  nPat = sqlite3_value_bytes(argv[0]);
+  testcase( nPat==db->aLimit[SQLITE_LIMIT_LIKE_PATTERN_LENGTH] );
+  testcase( nPat==db->aLimit[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]+1 );
+  if( nPat > db->aLimit[SQLITE_LIMIT_LIKE_PATTERN_LENGTH] ){
+    sqlite3_result_error(context, "LIKE or GLOB pattern too complex", -1);
+    return;
+  }
+  assert( zB==sqlite3_value_text(argv[0]) );  /* Encoding did not change */
+
+  if( argc==3 ){
+    /* The escape character string must consist of a single UTF-8 character.
+    ** Otherwise, return an error.
+    */
+    const unsigned char *zEsc = sqlite3_value_text(argv[2]);
+    if( zEsc==0 ) return;
+    if( sqlite3Utf8CharLen((char*)zEsc, -1)!=1 ){
+      sqlite3_result_error(context, 
+          "ESCAPE expression must be a single character", -1);
+      return;
+    }
+    escape = sqlite3Utf8Read(&zEsc);
+  }else{
+    escape = pInfo->matchSet;
+  }
+  if( zA && zB ){
+#ifdef SQLITE_TEST
+    sqlite3_like_count++;
+#endif
+    sqlite3_result_int(context, patternCompare(zB, zA, pInfo, escape));
+  }
+}
+
+/*
+** Implementation of the NULLIF(x,y) function.  The result is the first
+** argument if the arguments are different.  The result is NULL if the
+** arguments are equal to each other.
+*/
+static void nullifFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **argv
+){
+  CollSeq *pColl = sqlite3GetFuncCollSeq(context);
+  UNUSED_PARAMETER(NotUsed);
+  if( sqlite3MemCompare(argv[0], argv[1], pColl)!=0 ){
+    sqlite3_result_value(context, argv[0]);
+  }
+}
+
+/*
+** Implementation of the sqlite_version() function.  The result is the version
+** of the SQLite library that is running.
+*/
+static void versionFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **NotUsed2
+){
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  /* IMP: R-48699-48617 This function is an SQL wrapper around the
+  ** sqlite3_libversion() C-interface. */
+  sqlite3_result_text(context, sqlite3_libversion(), -1, SQLITE_STATIC);
+}
+
+/*
+** Implementation of the sqlite_source_id() function. The result is a string
+** that identifies the particular version of the source code used to build
+** SQLite.
+*/
+static void sourceidFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **NotUsed2
+){
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  /* IMP: R-24470-31136 This function is an SQL wrapper around the
+  ** sqlite3_sourceid() C interface. */
+  sqlite3_result_text(context, sqlite3_sourceid(), -1, SQLITE_STATIC);
+}
+
+/*
+** Implementation of the sqlite_log() function.  This is a wrapper around
+** sqlite3_log().  The return value is NULL.  The function exists purely for
+** its side-effects.
+*/
+static void errlogFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  UNUSED_PARAMETER(argc);
+  UNUSED_PARAMETER(context);
+  sqlite3_log(sqlite3_value_int(argv[0]), "%s", sqlite3_value_text(argv[1]));
+}
+
+/*
+** Implementation of the sqlite_compileoption_used() function.
+** The result is an integer that identifies if the compiler option
+** was used to build SQLite.
+*/
+#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
+static void compileoptionusedFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  const char *zOptName;
+  assert( argc==1 );
+  UNUSED_PARAMETER(argc);
+  /* IMP: R-39564-36305 The sqlite_compileoption_used() SQL
+  ** function is a wrapper around the sqlite3_compileoption_used() C/C++
+  ** function.
+  */
+  if( (zOptName = (const char*)sqlite3_value_text(argv[0]))!=0 ){
+    sqlite3_result_int(context, sqlite3_compileoption_used(zOptName));
+  }
+}
+#endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */
+
+/*
+** Implementation of the sqlite_compileoption_get() function. 
+** The result is a string that identifies the compiler options 
+** used to build SQLite.
+*/
+#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
+static void compileoptiongetFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  int n;
+  assert( argc==1 );
+  UNUSED_PARAMETER(argc);
+  /* IMP: R-04922-24076 The sqlite_compileoption_get() SQL function
+  ** is a wrapper around the sqlite3_compileoption_get() C/C++ function.
+  */
+  n = sqlite3_value_int(argv[0]);
+  sqlite3_result_text(context, sqlite3_compileoption_get(n), -1, SQLITE_STATIC);
+}
+#endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */
+
+/* Array for converting from half-bytes (nybbles) into ASCII hex
+** digits. */
+static const char hexdigits[] = {
+  '0', '1', '2', '3', '4', '5', '6', '7',
+  '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' 
+};
+
+/*
+** Implementation of the QUOTE() function.  This function takes a single
+** argument.  If the argument is numeric, the return value is the same as
+** the argument.  If the argument is NULL, the return value is the string
+** "NULL".  Otherwise, the argument is enclosed in single quotes with
+** single-quote escapes.
+*/
+static void quoteFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
+  assert( argc==1 );
+  UNUSED_PARAMETER(argc);
+  switch( sqlite3_value_type(argv[0]) ){
+    case SQLITE_FLOAT: {
+      double r1, r2;
+      char zBuf[50];
+      r1 = sqlite3_value_double(argv[0]);
+      sqlite3_snprintf(sizeof(zBuf), zBuf, "%!.15g", r1);
+      sqlite3AtoF(zBuf, &r2, 20, SQLITE_UTF8);
+      if( r1!=r2 ){
+        sqlite3_snprintf(sizeof(zBuf), zBuf, "%!.20e", r1);
+      }
+      sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
+      break;
+    }
+    case SQLITE_INTEGER: {
+      sqlite3_result_value(context, argv[0]);
+      break;
+    }
+    case SQLITE_BLOB: {
+      char *zText = 0;
+      char const *zBlob = sqlite3_value_blob(argv[0]);
+      int nBlob = sqlite3_value_bytes(argv[0]);
+      assert( zBlob==sqlite3_value_blob(argv[0]) ); /* No encoding change */
+      zText = (char *)contextMalloc(context, (2*(i64)nBlob)+4); 
+      if( zText ){
+        int i;
+        for(i=0; i<nBlob; i++){
+          zText[(i*2)+2] = hexdigits[(zBlob[i]>>4)&0x0F];
+          zText[(i*2)+3] = hexdigits[(zBlob[i])&0x0F];
+        }
+        zText[(nBlob*2)+2] = '\'';
+        zText[(nBlob*2)+3] = '\0';
+        zText[0] = 'X';
+        zText[1] = '\'';
+        sqlite3_result_text(context, zText, -1, SQLITE_TRANSIENT);
+        sqlite3_free(zText);
+      }
+      break;
+    }
+    case SQLITE_TEXT: {
+      int i,j;
+      u64 n;
+      const unsigned char *zArg = sqlite3_value_text(argv[0]);
+      char *z;
+
+      if( zArg==0 ) return;
+      for(i=0, n=0; zArg[i]; i++){ if( zArg[i]=='\'' ) n++; }
+      z = contextMalloc(context, ((i64)i)+((i64)n)+3);
+      if( z ){
+        z[0] = '\'';
+        for(i=0, j=1; zArg[i]; i++){
+          z[j++] = zArg[i];
+          if( zArg[i]=='\'' ){
+            z[j++] = '\'';
+          }
+        }
+        z[j++] = '\'';
+        z[j] = 0;
+        sqlite3_result_text(context, z, j, sqlite3_free);
+      }
+      break;
+    }
+    default: {
+      assert( sqlite3_value_type(argv[0])==SQLITE_NULL );
+      sqlite3_result_text(context, "NULL", 4, SQLITE_STATIC);
+      break;
+    }
+  }
+}
+
+/*
+** The unicode() function.  Return the integer unicode code-point value
+** for the first character of the input string. 
+*/
+static void unicodeFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  const unsigned char *z = sqlite3_value_text(argv[0]);
+  (void)argc;
+  if( z && z[0] ) sqlite3_result_int(context, sqlite3Utf8Read(&z));
+}
+
+/*
+** The char() function takes zero or more arguments, each of which is
+** an integer.  It constructs a string where each character of the string
+** is the unicode character for the corresponding integer argument.
+*/
+static void charFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  unsigned char *z, *zOut;
+  int i;
+  zOut = z = sqlite3_malloc64( argc*4+1 );
+  if( z==0 ){
+    sqlite3_result_error_nomem(context);
+    return;
+  }
+  for(i=0; i<argc; i++){
+    sqlite3_int64 x;
+    unsigned c;
+    x = sqlite3_value_int64(argv[i]);
+    if( x<0 || x>0x10ffff ) x = 0xfffd;
+    c = (unsigned)(x & 0x1fffff);
+    if( c<0x00080 ){
+      *zOut++ = (u8)(c&0xFF);
+    }else if( c<0x00800 ){
+      *zOut++ = 0xC0 + (u8)((c>>6)&0x1F);
+      *zOut++ = 0x80 + (u8)(c & 0x3F);
+    }else if( c<0x10000 ){
+      *zOut++ = 0xE0 + (u8)((c>>12)&0x0F);
+      *zOut++ = 0x80 + (u8)((c>>6) & 0x3F);
+      *zOut++ = 0x80 + (u8)(c & 0x3F);
+    }else{
+      *zOut++ = 0xF0 + (u8)((c>>18) & 0x07);
+      *zOut++ = 0x80 + (u8)((c>>12) & 0x3F);
+      *zOut++ = 0x80 + (u8)((c>>6) & 0x3F);
+      *zOut++ = 0x80 + (u8)(c & 0x3F);
+    }                                                    \
+  }
+  sqlite3_result_text64(context, (char*)z, zOut-z, sqlite3_free, SQLITE_UTF8);
+}
+
+/*
+** The hex() function.  Interpret the argument as a blob.  Return
+** a hexadecimal rendering as text.
+*/
+static void hexFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  int i, n;
+  const unsigned char *pBlob;
+  char *zHex, *z;
+  assert( argc==1 );
+  UNUSED_PARAMETER(argc);
+  pBlob = sqlite3_value_blob(argv[0]);
+  n = sqlite3_value_bytes(argv[0]);
+  assert( pBlob==sqlite3_value_blob(argv[0]) );  /* No encoding change */
+  z = zHex = contextMalloc(context, ((i64)n)*2 + 1);
+  if( zHex ){
+    for(i=0; i<n; i++, pBlob++){
+      unsigned char c = *pBlob;
+      *(z++) = hexdigits[(c>>4)&0xf];
+      *(z++) = hexdigits[c&0xf];
+    }
+    *z = 0;
+    sqlite3_result_text(context, zHex, n*2, sqlite3_free);
+  }
+}
+
+/*
+** The zeroblob(N) function returns a zero-filled blob of size N bytes.
+*/
+static void zeroblobFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  i64 n;
+  int rc;
+  assert( argc==1 );
+  UNUSED_PARAMETER(argc);
+  n = sqlite3_value_int64(argv[0]);
+  if( n<0 ) n = 0;
+  rc = sqlite3_result_zeroblob64(context, n); /* IMP: R-00293-64994 */
+  if( rc ){
+    sqlite3_result_error_code(context, rc);
+  }
+}
+
+/*
+** The replace() function.  Three arguments are all strings: call
+** them A, B, and C. The result is also a string which is derived
+** from A by replacing every occurrence of B with C.  The match
+** must be exact.  Collating sequences are not used.
+*/
+static void replaceFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  const unsigned char *zStr;        /* The input string A */
+  const unsigned char *zPattern;    /* The pattern string B */
+  const unsigned char *zRep;        /* The replacement string C */
+  unsigned char *zOut;              /* The output */
+  int nStr;                /* Size of zStr */
+  int nPattern;            /* Size of zPattern */
+  int nRep;                /* Size of zRep */
+  i64 nOut;                /* Maximum size of zOut */
+  int loopLimit;           /* Last zStr[] that might match zPattern[] */
+  int i, j;                /* Loop counters */
+
+  assert( argc==3 );
+  UNUSED_PARAMETER(argc);
+  zStr = sqlite3_value_text(argv[0]);
+  if( zStr==0 ) return;
+  nStr = sqlite3_value_bytes(argv[0]);
+  assert( zStr==sqlite3_value_text(argv[0]) );  /* No encoding change */
+  zPattern = sqlite3_value_text(argv[1]);
+  if( zPattern==0 ){
+    assert( sqlite3_value_type(argv[1])==SQLITE_NULL
+            || sqlite3_context_db_handle(context)->mallocFailed );
+    return;
+  }
+  if( zPattern[0]==0 ){
+    assert( sqlite3_value_type(argv[1])!=SQLITE_NULL );
+    sqlite3_result_value(context, argv[0]);
+    return;
+  }
+  nPattern = sqlite3_value_bytes(argv[1]);
+  assert( zPattern==sqlite3_value_text(argv[1]) );  /* No encoding change */
+  zRep = sqlite3_value_text(argv[2]);
+  if( zRep==0 ) return;
+  nRep = sqlite3_value_bytes(argv[2]);
+  assert( zRep==sqlite3_value_text(argv[2]) );
+  nOut = nStr + 1;
+  assert( nOut<SQLITE_MAX_LENGTH );
+  zOut = contextMalloc(context, (i64)nOut);
+  if( zOut==0 ){
+    return;
+  }
+  loopLimit = nStr - nPattern;  
+  for(i=j=0; i<=loopLimit; i++){
+    if( zStr[i]!=zPattern[0] || memcmp(&zStr[i], zPattern, nPattern) ){
+      zOut[j++] = zStr[i];
+    }else{
+      u8 *zOld;
+      sqlite3 *db = sqlite3_context_db_handle(context);
+      nOut += nRep - nPattern;
+      testcase( nOut-1==db->aLimit[SQLITE_LIMIT_LENGTH] );
+      testcase( nOut-2==db->aLimit[SQLITE_LIMIT_LENGTH] );
+      if( nOut-1>db->aLimit[SQLITE_LIMIT_LENGTH] ){
+        sqlite3_result_error_toobig(context);
+        sqlite3_free(zOut);
+        return;
+      }
+      zOld = zOut;
+      zOut = sqlite3_realloc64(zOut, (int)nOut);
+      if( zOut==0 ){
+        sqlite3_result_error_nomem(context);
+        sqlite3_free(zOld);
+        return;
+      }
+      memcpy(&zOut[j], zRep, nRep);
+      j += nRep;
+      i += nPattern-1;
+    }
+  }
+  assert( j+nStr-i+1==nOut );
+  memcpy(&zOut[j], &zStr[i], nStr-i);
+  j += nStr - i;
+  assert( j<=nOut );
+  zOut[j] = 0;
+  sqlite3_result_text(context, (char*)zOut, j, sqlite3_free);
+}
+
+/*
+** Implementation of the TRIM(), LTRIM(), and RTRIM() functions.
+** The userdata is 0x1 for left trim, 0x2 for right trim, 0x3 for both.
+*/
+static void trimFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  const unsigned char *zIn;         /* Input string */
+  const unsigned char *zCharSet;    /* Set of characters to trim */
+  int nIn;                          /* Number of bytes in input */
+  int flags;                        /* 1: trimleft  2: trimright  3: trim */
+  int i;                            /* Loop counter */
+  unsigned char *aLen = 0;          /* Length of each character in zCharSet */
+  unsigned char **azChar = 0;       /* Individual characters in zCharSet */
+  int nChar;                        /* Number of characters in zCharSet */
+
+  if( sqlite3_value_type(argv[0])==SQLITE_NULL ){
+    return;
+  }
+  zIn = sqlite3_value_text(argv[0]);
+  if( zIn==0 ) return;
+  nIn = sqlite3_value_bytes(argv[0]);
+  assert( zIn==sqlite3_value_text(argv[0]) );
+  if( argc==1 ){
+    static const unsigned char lenOne[] = { 1 };
+    static unsigned char * const azOne[] = { (u8*)" " };
+    nChar = 1;
+    aLen = (u8*)lenOne;
+    azChar = (unsigned char **)azOne;
+    zCharSet = 0;
+  }else if( (zCharSet = sqlite3_value_text(argv[1]))==0 ){
+    return;
+  }else{
+    const unsigned char *z;
+    for(z=zCharSet, nChar=0; *z; nChar++){
+      SQLITE_SKIP_UTF8(z);
+    }
+    if( nChar>0 ){
+      azChar = contextMalloc(context, ((i64)nChar)*(sizeof(char*)+1));
+      if( azChar==0 ){
+        return;
+      }
+      aLen = (unsigned char*)&azChar[nChar];
+      for(z=zCharSet, nChar=0; *z; nChar++){
+        azChar[nChar] = (unsigned char *)z;
+        SQLITE_SKIP_UTF8(z);
+        aLen[nChar] = (u8)(z - azChar[nChar]);
+      }
+    }
+  }
+  if( nChar>0 ){
+    flags = SQLITE_PTR_TO_INT(sqlite3_user_data(context));
+    if( flags & 1 ){
+      while( nIn>0 ){
+        int len = 0;
+        for(i=0; i<nChar; i++){
+          len = aLen[i];
+          if( len<=nIn && memcmp(zIn, azChar[i], len)==0 ) break;
+        }
+        if( i>=nChar ) break;
+        zIn += len;
+        nIn -= len;
+      }
+    }
+    if( flags & 2 ){
+      while( nIn>0 ){
+        int len = 0;
+        for(i=0; i<nChar; i++){
+          len = aLen[i];
+          if( len<=nIn && memcmp(&zIn[nIn-len],azChar[i],len)==0 ) break;
+        }
+        if( i>=nChar ) break;
+        nIn -= len;
+      }
+    }
+    if( zCharSet ){
+      sqlite3_free(azChar);
+    }
+  }
+  sqlite3_result_text(context, (char*)zIn, nIn, SQLITE_TRANSIENT);
+}
+
+
+#ifdef SQLITE_ENABLE_UNKNOWN_SQL_FUNCTION
+/*
+** The "unknown" function is automatically substituted in place of
+** any unrecognized function name when doing an EXPLAIN or EXPLAIN QUERY PLAN
+** when the SQLITE_ENABLE_UNKNOWN_FUNCTION compile-time option is used.
+** When the "sqlite3" command-line shell is built using this functionality,
+** that allows an EXPLAIN or EXPLAIN QUERY PLAN for complex queries
+** involving application-defined functions to be examined in a generic
+** sqlite3 shell.
+*/
+static void unknownFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  /* no-op */
+}
+#endif /*SQLITE_ENABLE_UNKNOWN_SQL_FUNCTION*/
+
+
+/* IMP: R-25361-16150 This function is omitted from SQLite by default. It
+** is only available if the SQLITE_SOUNDEX compile-time option is used
+** when SQLite is built.
+*/
+#ifdef SQLITE_SOUNDEX
+/*
+** Compute the soundex encoding of a word.
+**
+** IMP: R-59782-00072 The soundex(X) function returns a string that is the
+** soundex encoding of the string X. 
+*/
+static void soundexFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  char zResult[8];
+  const u8 *zIn;
+  int i, j;
+  static const unsigned char iCode[] = {
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 1, 2, 3, 0, 1, 2, 0, 0, 2, 2, 4, 5, 5, 0,
+    1, 2, 6, 2, 3, 0, 1, 0, 2, 0, 2, 0, 0, 0, 0, 0,
+    0, 0, 1, 2, 3, 0, 1, 2, 0, 0, 2, 2, 4, 5, 5, 0,
+    1, 2, 6, 2, 3, 0, 1, 0, 2, 0, 2, 0, 0, 0, 0, 0,
+  };
+  assert( argc==1 );
+  zIn = (u8*)sqlite3_value_text(argv[0]);
+  if( zIn==0 ) zIn = (u8*)"";
+  for(i=0; zIn[i] && !sqlite3Isalpha(zIn[i]); i++){}
+  if( zIn[i] ){
+    u8 prevcode = iCode[zIn[i]&0x7f];
+    zResult[0] = sqlite3Toupper(zIn[i]);
+    for(j=1; j<4 && zIn[i]; i++){
+      int code = iCode[zIn[i]&0x7f];
+      if( code>0 ){
+        if( code!=prevcode ){
+          prevcode = code;
+          zResult[j++] = code + '0';
+        }
+      }else{
+        prevcode = 0;
+      }
+    }
+    while( j<4 ){
+      zResult[j++] = '0';
+    }
+    zResult[j] = 0;
+    sqlite3_result_text(context, zResult, 4, SQLITE_TRANSIENT);
+  }else{
+    /* IMP: R-64894-50321 The string "?000" is returned if the argument
+    ** is NULL or contains no ASCII alphabetic characters. */
+    sqlite3_result_text(context, "?000", 4, SQLITE_STATIC);
+  }
+}
+#endif /* SQLITE_SOUNDEX */
+
+#ifndef SQLITE_OMIT_LOAD_EXTENSION
+/*
+** A function that loads a shared-library extension then returns NULL.
+*/
+static void loadExt(sqlite3_context *context, int argc, sqlite3_value **argv){
+  const char *zFile = (const char *)sqlite3_value_text(argv[0]);
+  const char *zProc;
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  char *zErrMsg = 0;
+
+  /* Disallow the load_extension() SQL function unless the SQLITE_LoadExtFunc
+  ** flag is set.  See the sqlite3_enable_load_extension() API.
+  */
+  if( (db->flags & SQLITE_LoadExtFunc)==0 ){
+    sqlite3_result_error(context, "not authorized", -1);
+    return;
+  }
+
+  if( argc==2 ){
+    zProc = (const char *)sqlite3_value_text(argv[1]);
+  }else{
+    zProc = 0;
+  }
+  if( zFile && sqlite3_load_extension(db, zFile, zProc, &zErrMsg) ){
+    sqlite3_result_error(context, zErrMsg, -1);
+    sqlite3_free(zErrMsg);
+  }
+}
+#endif
+
+
+/*
+** An instance of the following structure holds the context of a
+** sum() or avg() aggregate computation.
+*/
+typedef struct SumCtx SumCtx;
+struct SumCtx {
+  double rSum;      /* Floating point sum */
+  i64 iSum;         /* Integer sum */   
+  i64 cnt;          /* Number of elements summed */
+  u8 overflow;      /* True if integer overflow seen */
+  u8 approx;        /* True if non-integer value was input to the sum */
+};
+
+/*
+** Routines used to compute the sum, average, and total.
+**
+** The SUM() function follows the (broken) SQL standard which means
+** that it returns NULL if it sums over no inputs.  TOTAL returns
+** 0.0 in that case.  In addition, TOTAL always returns a float where
+** SUM might return an integer if it never encounters a floating point
+** value.  TOTAL never fails, but SUM might through an exception if
+** it overflows an integer.
+*/
+static void sumStep(sqlite3_context *context, int argc, sqlite3_value **argv){
+  SumCtx *p;
+  int type;
+  assert( argc==1 );
+  UNUSED_PARAMETER(argc);
+  p = sqlite3_aggregate_context(context, sizeof(*p));
+  type = sqlite3_value_numeric_type(argv[0]);
+  if( p && type!=SQLITE_NULL ){
+    p->cnt++;
+    if( type==SQLITE_INTEGER ){
+      i64 v = sqlite3_value_int64(argv[0]);
+      p->rSum += v;
+      if( (p->approx|p->overflow)==0 && sqlite3AddInt64(&p->iSum, v) ){
+        p->overflow = 1;
+      }
+    }else{
+      p->rSum += sqlite3_value_double(argv[0]);
+      p->approx = 1;
+    }
+  }
+}
+static void sumFinalize(sqlite3_context *context){
+  SumCtx *p;
+  p = sqlite3_aggregate_context(context, 0);
+  if( p && p->cnt>0 ){
+    if( p->overflow ){
+      sqlite3_result_error(context,"integer overflow",-1);
+    }else if( p->approx ){
+      sqlite3_result_double(context, p->rSum);
+    }else{
+      sqlite3_result_int64(context, p->iSum);
+    }
+  }
+}
+static void avgFinalize(sqlite3_context *context){
+  SumCtx *p;
+  p = sqlite3_aggregate_context(context, 0);
+  if( p && p->cnt>0 ){
+    sqlite3_result_double(context, p->rSum/(double)p->cnt);
+  }
+}
+static void totalFinalize(sqlite3_context *context){
+  SumCtx *p;
+  p = sqlite3_aggregate_context(context, 0);
+  /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
+  sqlite3_result_double(context, p ? p->rSum : (double)0);
+}
+
+/*
+** The following structure keeps track of state information for the
+** count() aggregate function.
+*/
+typedef struct CountCtx CountCtx;
+struct CountCtx {
+  i64 n;
+};
+
+/*
+** Routines to implement the count() aggregate function.
+*/
+static void countStep(sqlite3_context *context, int argc, sqlite3_value **argv){
+  CountCtx *p;
+  p = sqlite3_aggregate_context(context, sizeof(*p));
+  if( (argc==0 || SQLITE_NULL!=sqlite3_value_type(argv[0])) && p ){
+    p->n++;
+  }
+
+#ifndef SQLITE_OMIT_DEPRECATED
+  /* The sqlite3_aggregate_count() function is deprecated.  But just to make
+  ** sure it still operates correctly, verify that its count agrees with our 
+  ** internal count when using count(*) and when the total count can be
+  ** expressed as a 32-bit integer. */
+  assert( argc==1 || p==0 || p->n>0x7fffffff
+          || p->n==sqlite3_aggregate_count(context) );
+#endif
+}   
+static void countFinalize(sqlite3_context *context){
+  CountCtx *p;
+  p = sqlite3_aggregate_context(context, 0);
+  sqlite3_result_int64(context, p ? p->n : 0);
+}
+
+/*
+** Routines to implement min() and max() aggregate functions.
+*/
+static void minmaxStep(
+  sqlite3_context *context, 
+  int NotUsed, 
+  sqlite3_value **argv
+){
+  Mem *pArg  = (Mem *)argv[0];
+  Mem *pBest;
+  UNUSED_PARAMETER(NotUsed);
+
+  pBest = (Mem *)sqlite3_aggregate_context(context, sizeof(*pBest));
+  if( !pBest ) return;
+
+  if( sqlite3_value_type(argv[0])==SQLITE_NULL ){
+    if( pBest->flags ) sqlite3SkipAccumulatorLoad(context);
+  }else if( pBest->flags ){
+    int max;
+    int cmp;
+    CollSeq *pColl = sqlite3GetFuncCollSeq(context);
+    /* This step function is used for both the min() and max() aggregates,
+    ** the only difference between the two being that the sense of the
+    ** comparison is inverted. For the max() aggregate, the
+    ** sqlite3_user_data() function returns (void *)-1. For min() it
+    ** returns (void *)db, where db is the sqlite3* database pointer.
+    ** Therefore the next statement sets variable 'max' to 1 for the max()
+    ** aggregate, or 0 for min().
+    */
+    max = sqlite3_user_data(context)!=0;
+    cmp = sqlite3MemCompare(pBest, pArg, pColl);
+    if( (max && cmp<0) || (!max && cmp>0) ){
+      sqlite3VdbeMemCopy(pBest, pArg);
+    }else{
+      sqlite3SkipAccumulatorLoad(context);
+    }
+  }else{
+    pBest->db = sqlite3_context_db_handle(context);
+    sqlite3VdbeMemCopy(pBest, pArg);
+  }
+}
+static void minMaxFinalize(sqlite3_context *context){
+  sqlite3_value *pRes;
+  pRes = (sqlite3_value *)sqlite3_aggregate_context(context, 0);
+  if( pRes ){
+    if( pRes->flags ){
+      sqlite3_result_value(context, pRes);
+    }
+    sqlite3VdbeMemRelease(pRes);
+  }
+}
+
+/*
+** group_concat(EXPR, ?SEPARATOR?)
+*/
+static void groupConcatStep(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  const char *zVal;
+  StrAccum *pAccum;
+  const char *zSep;
+  int nVal, nSep;
+  assert( argc==1 || argc==2 );
+  if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
+  pAccum = (StrAccum*)sqlite3_aggregate_context(context, sizeof(*pAccum));
+
+  if( pAccum ){
+    sqlite3 *db = sqlite3_context_db_handle(context);
+    int firstTerm = pAccum->mxAlloc==0;
+    pAccum->mxAlloc = db->aLimit[SQLITE_LIMIT_LENGTH];
+    if( !firstTerm ){
+      if( argc==2 ){
+        zSep = (char*)sqlite3_value_text(argv[1]);
+        nSep = sqlite3_value_bytes(argv[1]);
+      }else{
+        zSep = ",";
+        nSep = 1;
+      }
+      if( nSep ) sqlite3StrAccumAppend(pAccum, zSep, nSep);
+    }
+    zVal = (char*)sqlite3_value_text(argv[0]);
+    nVal = sqlite3_value_bytes(argv[0]);
+    if( zVal ) sqlite3StrAccumAppend(pAccum, zVal, nVal);
+  }
+}
+static void groupConcatFinalize(sqlite3_context *context){
+  StrAccum *pAccum;
+  pAccum = sqlite3_aggregate_context(context, 0);
+  if( pAccum ){
+    if( pAccum->accError==STRACCUM_TOOBIG ){
+      sqlite3_result_error_toobig(context);
+    }else if( pAccum->accError==STRACCUM_NOMEM ){
+      sqlite3_result_error_nomem(context);
+    }else{    
+      sqlite3_result_text(context, sqlite3StrAccumFinish(pAccum), -1, 
+                          sqlite3_free);
+    }
+  }
+}
+
+/*
+** This routine does per-connection function registration.  Most
+** of the built-in functions above are part of the global function set.
+** This routine only deals with those that are not global.
+*/
+SQLITE_PRIVATE void sqlite3RegisterPerConnectionBuiltinFunctions(sqlite3 *db){
+  int rc = sqlite3_overload_function(db, "MATCH", 2);
+/* BEGIN SQLCIPHER */
+#ifdef SQLITE_HAS_CODEC
+#ifndef OMIT_EXPORT
+  extern void sqlcipher_exportFunc(sqlite3_context *, int, sqlite3_value **);
+#endif
+#endif
+/* END SQLCIPHER */
+  assert( rc==SQLITE_NOMEM || rc==SQLITE_OK );
+  if( rc==SQLITE_NOMEM ){
+    sqlite3OomFault(db);
+  }
+/* BEGIN SQLCIPHER */
+#ifdef SQLITE_HAS_CODEC
+#ifndef OMIT_EXPORT
+  sqlite3CreateFunc(db, "sqlcipher_export", 1, SQLITE_TEXT, 0, sqlcipher_exportFunc, 0, 0, 0);
+#endif
+#endif
+/* END SQLCIPHER */
+}
+
+/*
+** Set the LIKEOPT flag on the 2-argument function with the given name.
+*/
+static void setLikeOptFlag(sqlite3 *db, const char *zName, u8 flagVal){
+  FuncDef *pDef;
+  pDef = sqlite3FindFunction(db, zName, 2, SQLITE_UTF8, 0);
+  if( ALWAYS(pDef) ){
+    pDef->funcFlags |= flagVal;
+  }
+}
+
+/*
+** Register the built-in LIKE and GLOB functions.  The caseSensitive
+** parameter determines whether or not the LIKE operator is case
+** sensitive.  GLOB is always case sensitive.
+*/
+SQLITE_PRIVATE void sqlite3RegisterLikeFunctions(sqlite3 *db, int caseSensitive){
+  struct compareInfo *pInfo;
+  if( caseSensitive ){
+    pInfo = (struct compareInfo*)&likeInfoAlt;
+  }else{
+    pInfo = (struct compareInfo*)&likeInfoNorm;
+  }
+  sqlite3CreateFunc(db, "like", 2, SQLITE_UTF8, pInfo, likeFunc, 0, 0, 0);
+  sqlite3CreateFunc(db, "like", 3, SQLITE_UTF8, pInfo, likeFunc, 0, 0, 0);
+  sqlite3CreateFunc(db, "glob", 2, SQLITE_UTF8, 
+      (struct compareInfo*)&globInfo, likeFunc, 0, 0, 0);
+  setLikeOptFlag(db, "glob", SQLITE_FUNC_LIKE | SQLITE_FUNC_CASE);
+  setLikeOptFlag(db, "like", 
+      caseSensitive ? (SQLITE_FUNC_LIKE | SQLITE_FUNC_CASE) : SQLITE_FUNC_LIKE);
+}
+
+/*
+** pExpr points to an expression which implements a function.  If
+** it is appropriate to apply the LIKE optimization to that function
+** then set aWc[0] through aWc[2] to the wildcard characters and
+** return TRUE.  If the function is not a LIKE-style function then
+** return FALSE.
+**
+** *pIsNocase is set to true if uppercase and lowercase are equivalent for
+** the function (default for LIKE).  If the function makes the distinction
+** between uppercase and lowercase (as does GLOB) then *pIsNocase is set to
+** false.
+*/
+SQLITE_PRIVATE int sqlite3IsLikeFunction(sqlite3 *db, Expr *pExpr, int *pIsNocase, char *aWc){
+  FuncDef *pDef;
+  if( pExpr->op!=TK_FUNCTION 
+   || !pExpr->x.pList 
+   || pExpr->x.pList->nExpr!=2
+  ){
+    return 0;
+  }
+  assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
+  pDef = sqlite3FindFunction(db, pExpr->u.zToken, 2, SQLITE_UTF8, 0);
+  if( NEVER(pDef==0) || (pDef->funcFlags & SQLITE_FUNC_LIKE)==0 ){
+    return 0;
+  }
+
+  /* The memcpy() statement assumes that the wildcard characters are
+  ** the first three statements in the compareInfo structure.  The
+  ** asserts() that follow verify that assumption
+  */
+  memcpy(aWc, pDef->pUserData, 3);
+  assert( (char*)&likeInfoAlt == (char*)&likeInfoAlt.matchAll );
+  assert( &((char*)&likeInfoAlt)[1] == (char*)&likeInfoAlt.matchOne );
+  assert( &((char*)&likeInfoAlt)[2] == (char*)&likeInfoAlt.matchSet );
+  *pIsNocase = (pDef->funcFlags & SQLITE_FUNC_CASE)==0;
+  return 1;
+}
+
+/*
+** All of the FuncDef structures in the aBuiltinFunc[] array above
+** to the global function hash table.  This occurs at start-time (as
+** a consequence of calling sqlite3_initialize()).
+**
+** After this routine runs
+*/
+SQLITE_PRIVATE void sqlite3RegisterBuiltinFunctions(void){
+  /*
+  ** The following array holds FuncDef structures for all of the functions
+  ** defined in this file.
+  **
+  ** The array cannot be constant since changes are made to the
+  ** FuncDef.pHash elements at start-time.  The elements of this array
+  ** are read-only after initialization is complete.
+  **
+  ** For peak efficiency, put the most frequently used function last.
+  */
+  static FuncDef aBuiltinFunc[] = {
+#ifdef SQLITE_SOUNDEX
+    FUNCTION(soundex,            1, 0, 0, soundexFunc      ),
+#endif
+#ifndef SQLITE_OMIT_LOAD_EXTENSION
+    VFUNCTION(load_extension,    1, 0, 0, loadExt          ),
+    VFUNCTION(load_extension,    2, 0, 0, loadExt          ),
+#endif
+#if SQLITE_USER_AUTHENTICATION
+    FUNCTION(sqlite_crypt,       2, 0, 0, sqlite3CryptFunc ),
+#endif
+#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
+    DFUNCTION(sqlite_compileoption_used,1, 0, 0, compileoptionusedFunc  ),
+    DFUNCTION(sqlite_compileoption_get, 1, 0, 0, compileoptiongetFunc  ),
+#endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */
+    FUNCTION2(unlikely,          1, 0, 0, noopFunc,  SQLITE_FUNC_UNLIKELY),
+    FUNCTION2(likelihood,        2, 0, 0, noopFunc,  SQLITE_FUNC_UNLIKELY),
+    FUNCTION2(likely,            1, 0, 0, noopFunc,  SQLITE_FUNC_UNLIKELY),
+    FUNCTION(ltrim,              1, 1, 0, trimFunc         ),
+    FUNCTION(ltrim,              2, 1, 0, trimFunc         ),
+    FUNCTION(rtrim,              1, 2, 0, trimFunc         ),
+    FUNCTION(rtrim,              2, 2, 0, trimFunc         ),
+    FUNCTION(trim,               1, 3, 0, trimFunc         ),
+    FUNCTION(trim,               2, 3, 0, trimFunc         ),
+    FUNCTION(min,               -1, 0, 1, minmaxFunc       ),
+    FUNCTION(min,                0, 0, 1, 0                ),
+    AGGREGATE2(min,              1, 0, 1, minmaxStep,      minMaxFinalize,
+                                          SQLITE_FUNC_MINMAX ),
+    FUNCTION(max,               -1, 1, 1, minmaxFunc       ),
+    FUNCTION(max,                0, 1, 1, 0                ),
+    AGGREGATE2(max,              1, 1, 1, minmaxStep,      minMaxFinalize,
+                                          SQLITE_FUNC_MINMAX ),
+    FUNCTION2(typeof,            1, 0, 0, typeofFunc,  SQLITE_FUNC_TYPEOF),
+    FUNCTION2(length,            1, 0, 0, lengthFunc,  SQLITE_FUNC_LENGTH),
+    FUNCTION(instr,              2, 0, 0, instrFunc        ),
+    FUNCTION(printf,            -1, 0, 0, printfFunc       ),
+    FUNCTION(unicode,            1, 0, 0, unicodeFunc      ),
+    FUNCTION(char,              -1, 0, 0, charFunc         ),
+    FUNCTION(abs,                1, 0, 0, absFunc          ),
+#ifndef SQLITE_OMIT_FLOATING_POINT
+    FUNCTION(round,              1, 0, 0, roundFunc        ),
+    FUNCTION(round,              2, 0, 0, roundFunc        ),
+#endif
+    FUNCTION(upper,              1, 0, 0, upperFunc        ),
+    FUNCTION(lower,              1, 0, 0, lowerFunc        ),
+    FUNCTION(hex,                1, 0, 0, hexFunc          ),
+    FUNCTION2(ifnull,            2, 0, 0, noopFunc,  SQLITE_FUNC_COALESCE),
+    VFUNCTION(random,            0, 0, 0, randomFunc       ),
+    VFUNCTION(randomblob,        1, 0, 0, randomBlob       ),
+    FUNCTION(nullif,             2, 0, 1, nullifFunc       ),
+    DFUNCTION(sqlite_version,    0, 0, 0, versionFunc      ),
+    DFUNCTION(sqlite_source_id,  0, 0, 0, sourceidFunc     ),
+    FUNCTION(sqlite_log,         2, 0, 0, errlogFunc       ),
+    FUNCTION(quote,              1, 0, 0, quoteFunc        ),
+    VFUNCTION(last_insert_rowid, 0, 0, 0, last_insert_rowid),
+    VFUNCTION(changes,           0, 0, 0, changes          ),
+    VFUNCTION(total_changes,     0, 0, 0, total_changes    ),
+    FUNCTION(replace,            3, 0, 0, replaceFunc      ),
+    FUNCTION(zeroblob,           1, 0, 0, zeroblobFunc     ),
+    FUNCTION(substr,             2, 0, 0, substrFunc       ),
+    FUNCTION(substr,             3, 0, 0, substrFunc       ),
+    AGGREGATE(sum,               1, 0, 0, sumStep,         sumFinalize    ),
+    AGGREGATE(total,             1, 0, 0, sumStep,         totalFinalize    ),
+    AGGREGATE(avg,               1, 0, 0, sumStep,         avgFinalize    ),
+    AGGREGATE2(count,            0, 0, 0, countStep,       countFinalize,
+               SQLITE_FUNC_COUNT  ),
+    AGGREGATE(count,             1, 0, 0, countStep,       countFinalize  ),
+    AGGREGATE(group_concat,      1, 0, 0, groupConcatStep, groupConcatFinalize),
+    AGGREGATE(group_concat,      2, 0, 0, groupConcatStep, groupConcatFinalize),
+  
+    LIKEFUNC(glob, 2, &globInfo, SQLITE_FUNC_LIKE|SQLITE_FUNC_CASE),
+#ifdef SQLITE_CASE_SENSITIVE_LIKE
+    LIKEFUNC(like, 2, &likeInfoAlt, SQLITE_FUNC_LIKE|SQLITE_FUNC_CASE),
+    LIKEFUNC(like, 3, &likeInfoAlt, SQLITE_FUNC_LIKE|SQLITE_FUNC_CASE),
+#else
+    LIKEFUNC(like, 2, &likeInfoNorm, SQLITE_FUNC_LIKE),
+    LIKEFUNC(like, 3, &likeInfoNorm, SQLITE_FUNC_LIKE),
+#endif
+#ifdef SQLITE_ENABLE_UNKNOWN_SQL_FUNCTION
+    FUNCTION(unknown,           -1, 0, 0, unknownFunc      ),
+#endif
+    FUNCTION(coalesce,           1, 0, 0, 0                ),
+    FUNCTION(coalesce,           0, 0, 0, 0                ),
+    FUNCTION2(coalesce,         -1, 0, 0, noopFunc,  SQLITE_FUNC_COALESCE),
+  };
+#ifndef SQLITE_OMIT_ALTERTABLE
+  sqlite3AlterFunctions();
+#endif
+#if defined(SQLITE_ENABLE_STAT3) || defined(SQLITE_ENABLE_STAT4)
+  sqlite3AnalyzeFunctions();
+#endif
+  sqlite3RegisterDateTimeFunctions();
+  sqlite3InsertBuiltinFuncs(aBuiltinFunc, ArraySize(aBuiltinFunc));
+
+#if 0  /* Enable to print out how the built-in functions are hashed */
+  {
+    int i;
+    FuncDef *p;
+    for(i=0; i<SQLITE_FUNC_HASH_SZ; i++){
+      printf("FUNC-HASH %02d:", i);
+      for(p=sqlite3BuiltinFunctions.a[i]; p; p=p->u.pHash){
+        int n = sqlite3Strlen30(p->zName);
+        int h = p->zName[0] + n;
+        printf(" %s(%d)", p->zName, h);
+      }
+      printf("\n");
+    }
+  }
+#endif
+}
+
+/************** End of func.c ************************************************/
+/************** Begin file fkey.c ********************************************/
+/*
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains code used by the compiler to add foreign key
+** support to compiled SQL statements.
+*/
+/* #include "sqliteInt.h" */
+
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+#ifndef SQLITE_OMIT_TRIGGER
+
+/*
+** Deferred and Immediate FKs
+** --------------------------
+**
+** Foreign keys in SQLite come in two flavours: deferred and immediate.
+** If an immediate foreign key constraint is violated,
+** SQLITE_CONSTRAINT_FOREIGNKEY is returned and the current
+** statement transaction rolled back. If a 
+** deferred foreign key constraint is violated, no action is taken 
+** immediately. However if the application attempts to commit the 
+** transaction before fixing the constraint violation, the attempt fails.
+**
+** Deferred constraints are implemented using a simple counter associated
+** with the database handle. The counter is set to zero each time a 
+** database transaction is opened. Each time a statement is executed 
+** that causes a foreign key violation, the counter is incremented. Each
+** time a statement is executed that removes an existing violation from
+** the database, the counter is decremented. When the transaction is
+** committed, the commit fails if the current value of the counter is
+** greater than zero. This scheme has two big drawbacks:
+**
+**   * When a commit fails due to a deferred foreign key constraint, 
+**     there is no way to tell which foreign constraint is not satisfied,
+**     or which row it is not satisfied for.
+**
+**   * If the database contains foreign key violations when the 
+**     transaction is opened, this may cause the mechanism to malfunction.
+**
+** Despite these problems, this approach is adopted as it seems simpler
+** than the alternatives.
+**
+** INSERT operations:
+**
+**   I.1) For each FK for which the table is the child table, search
+**        the parent table for a match. If none is found increment the
+**        constraint counter.
+**
+**   I.2) For each FK for which the table is the parent table, 
+**        search the child table for rows that correspond to the new
+**        row in the parent table. Decrement the counter for each row
+**        found (as the constraint is now satisfied).
+**
+** DELETE operations:
+**
+**   D.1) For each FK for which the table is the child table, 
+**        search the parent table for a row that corresponds to the 
+**        deleted row in the child table. If such a row is not found, 
+**        decrement the counter.
+**
+**   D.2) For each FK for which the table is the parent table, search 
+**        the child table for rows that correspond to the deleted row 
+**        in the parent table. For each found increment the counter.
+**
+** UPDATE operations:
+**
+**   An UPDATE command requires that all 4 steps above are taken, but only
+**   for FK constraints for which the affected columns are actually 
+**   modified (values must be compared at runtime).
+**
+** Note that I.1 and D.1 are very similar operations, as are I.2 and D.2.
+** This simplifies the implementation a bit.
+**
+** For the purposes of immediate FK constraints, the OR REPLACE conflict
+** resolution is considered to delete rows before the new row is inserted.
+** If a delete caused by OR REPLACE violates an FK constraint, an exception
+** is thrown, even if the FK constraint would be satisfied after the new 
+** row is inserted.
+**
+** Immediate constraints are usually handled similarly. The only difference 
+** is that the counter used is stored as part of each individual statement
+** object (struct Vdbe). If, after the statement has run, its immediate
+** constraint counter is greater than zero,
+** it returns SQLITE_CONSTRAINT_FOREIGNKEY
+** and the statement transaction is rolled back. An exception is an INSERT
+** statement that inserts a single row only (no triggers). In this case,
+** instead of using a counter, an exception is thrown immediately if the
+** INSERT violates a foreign key constraint. This is necessary as such
+** an INSERT does not open a statement transaction.
+**
+** TODO: How should dropping a table be handled? How should renaming a 
+** table be handled?
+**
+**
+** Query API Notes
+** ---------------
+**
+** Before coding an UPDATE or DELETE row operation, the code-generator
+** for those two operations needs to know whether or not the operation
+** requires any FK processing and, if so, which columns of the original
+** row are required by the FK processing VDBE code (i.e. if FKs were
+** implemented using triggers, which of the old.* columns would be 
+** accessed). No information is required by the code-generator before
+** coding an INSERT operation. The functions used by the UPDATE/DELETE
+** generation code to query for this information are:
+**
+**   sqlite3FkRequired() - Test to see if FK processing is required.
+**   sqlite3FkOldmask()  - Query for the set of required old.* columns.
+**
+**
+** Externally accessible module functions
+** --------------------------------------
+**
+**   sqlite3FkCheck()    - Check for foreign key violations.
+**   sqlite3FkActions()  - Code triggers for ON UPDATE/ON DELETE actions.
+**   sqlite3FkDelete()   - Delete an FKey structure.
+*/
+
+/*
+** VDBE Calling Convention
+** -----------------------
+**
+** Example:
+**
+**   For the following INSERT statement:
+**
+**     CREATE TABLE t1(a, b INTEGER PRIMARY KEY, c);
+**     INSERT INTO t1 VALUES(1, 2, 3.1);
+**
+**   Register (x):        2    (type integer)
+**   Register (x+1):      1    (type integer)
+**   Register (x+2):      NULL (type NULL)
+**   Register (x+3):      3.1  (type real)
+*/
+
+/*
+** A foreign key constraint requires that the key columns in the parent
+** table are collectively subject to a UNIQUE or PRIMARY KEY constraint.
+** Given that pParent is the parent table for foreign key constraint pFKey, 
+** search the schema for a unique index on the parent key columns. 
+**
+** If successful, zero is returned. If the parent key is an INTEGER PRIMARY 
+** KEY column, then output variable *ppIdx is set to NULL. Otherwise, *ppIdx 
+** is set to point to the unique index. 
+** 
+** If the parent key consists of a single column (the foreign key constraint
+** is not a composite foreign key), output variable *paiCol is set to NULL.
+** Otherwise, it is set to point to an allocated array of size N, where
+** N is the number of columns in the parent key. The first element of the
+** array is the index of the child table column that is mapped by the FK
+** constraint to the parent table column stored in the left-most column
+** of index *ppIdx. The second element of the array is the index of the
+** child table column that corresponds to the second left-most column of
+** *ppIdx, and so on.
+**
+** If the required index cannot be found, either because:
+**
+**   1) The named parent key columns do not exist, or
+**
+**   2) The named parent key columns do exist, but are not subject to a
+**      UNIQUE or PRIMARY KEY constraint, or
+**
+**   3) No parent key columns were provided explicitly as part of the
+**      foreign key definition, and the parent table does not have a
+**      PRIMARY KEY, or
+**
+**   4) No parent key columns were provided explicitly as part of the
+**      foreign key definition, and the PRIMARY KEY of the parent table 
+**      consists of a different number of columns to the child key in 
+**      the child table.
+**
+** then non-zero is returned, and a "foreign key mismatch" error loaded
+** into pParse. If an OOM error occurs, non-zero is returned and the
+** pParse->db->mallocFailed flag is set.
+*/
+SQLITE_PRIVATE int sqlite3FkLocateIndex(
+  Parse *pParse,                  /* Parse context to store any error in */
+  Table *pParent,                 /* Parent table of FK constraint pFKey */
+  FKey *pFKey,                    /* Foreign key to find index for */
+  Index **ppIdx,                  /* OUT: Unique index on parent table */
+  int **paiCol                    /* OUT: Map of index columns in pFKey */
+){
+  Index *pIdx = 0;                    /* Value to return via *ppIdx */
+  int *aiCol = 0;                     /* Value to return via *paiCol */
+  int nCol = pFKey->nCol;             /* Number of columns in parent key */
+  char *zKey = pFKey->aCol[0].zCol;   /* Name of left-most parent key column */
+
+  /* The caller is responsible for zeroing output parameters. */
+  assert( ppIdx && *ppIdx==0 );
+  assert( !paiCol || *paiCol==0 );
+  assert( pParse );
+
+  /* If this is a non-composite (single column) foreign key, check if it 
+  ** maps to the INTEGER PRIMARY KEY of table pParent. If so, leave *ppIdx 
+  ** and *paiCol set to zero and return early. 
+  **
+  ** Otherwise, for a composite foreign key (more than one column), allocate
+  ** space for the aiCol array (returned via output parameter *paiCol).
+  ** Non-composite foreign keys do not require the aiCol array.
+  */
+  if( nCol==1 ){
+    /* The FK maps to the IPK if any of the following are true:
+    **
+    **   1) There is an INTEGER PRIMARY KEY column and the FK is implicitly 
+    **      mapped to the primary key of table pParent, or
+    **   2) The FK is explicitly mapped to a column declared as INTEGER
+    **      PRIMARY KEY.
+    */
+    if( pParent->iPKey>=0 ){
+      if( !zKey ) return 0;
+      if( !sqlite3StrICmp(pParent->aCol[pParent->iPKey].zName, zKey) ) return 0;
+    }
+  }else if( paiCol ){
+    assert( nCol>1 );
+    aiCol = (int *)sqlite3DbMallocRawNN(pParse->db, nCol*sizeof(int));
+    if( !aiCol ) return 1;
+    *paiCol = aiCol;
+  }
+
+  for(pIdx=pParent->pIndex; pIdx; pIdx=pIdx->pNext){
+    if( pIdx->nKeyCol==nCol && IsUniqueIndex(pIdx) ){ 
+      /* pIdx is a UNIQUE index (or a PRIMARY KEY) and has the right number
+      ** of columns. If each indexed column corresponds to a foreign key
+      ** column of pFKey, then this index is a winner.  */
+
+      if( zKey==0 ){
+        /* If zKey is NULL, then this foreign key is implicitly mapped to 
+        ** the PRIMARY KEY of table pParent. The PRIMARY KEY index may be 
+        ** identified by the test.  */
+        if( IsPrimaryKeyIndex(pIdx) ){
+          if( aiCol ){
+            int i;
+            for(i=0; i<nCol; i++) aiCol[i] = pFKey->aCol[i].iFrom;
+          }
+          break;
+        }
+      }else{
+        /* If zKey is non-NULL, then this foreign key was declared to
+        ** map to an explicit list of columns in table pParent. Check if this
+        ** index matches those columns. Also, check that the index uses
+        ** the default collation sequences for each column. */
+        int i, j;
+        for(i=0; i<nCol; i++){
+          i16 iCol = pIdx->aiColumn[i];     /* Index of column in parent tbl */
+          const char *zDfltColl;            /* Def. collation for column */
+          char *zIdxCol;                    /* Name of indexed column */
+
+          if( iCol<0 ) break; /* No foreign keys against expression indexes */
+
+          /* If the index uses a collation sequence that is different from
+          ** the default collation sequence for the column, this index is
+          ** unusable. Bail out early in this case.  */
+          zDfltColl = pParent->aCol[iCol].zColl;
+          if( !zDfltColl ) zDfltColl = sqlite3StrBINARY;
+          if( sqlite3StrICmp(pIdx->azColl[i], zDfltColl) ) break;
+
+          zIdxCol = pParent->aCol[iCol].zName;
+          for(j=0; j<nCol; j++){
+            if( sqlite3StrICmp(pFKey->aCol[j].zCol, zIdxCol)==0 ){
+              if( aiCol ) aiCol[i] = pFKey->aCol[j].iFrom;
+              break;
+            }
+          }
+          if( j==nCol ) break;
+        }
+        if( i==nCol ) break;      /* pIdx is usable */
+      }
+    }
+  }
+
+  if( !pIdx ){
+    if( !pParse->disableTriggers ){
+      sqlite3ErrorMsg(pParse,
+           "foreign key mismatch - \"%w\" referencing \"%w\"",
+           pFKey->pFrom->zName, pFKey->zTo);
+    }
+    sqlite3DbFree(pParse->db, aiCol);
+    return 1;
+  }
+
+  *ppIdx = pIdx;
+  return 0;
+}
+
+/*
+** This function is called when a row is inserted into or deleted from the 
+** child table of foreign key constraint pFKey. If an SQL UPDATE is executed 
+** on the child table of pFKey, this function is invoked twice for each row
+** affected - once to "delete" the old row, and then again to "insert" the
+** new row.
+**
+** Each time it is called, this function generates VDBE code to locate the
+** row in the parent table that corresponds to the row being inserted into 
+** or deleted from the child table. If the parent row can be found, no 
+** special action is taken. Otherwise, if the parent row can *not* be
+** found in the parent table:
+**
+**   Operation | FK type   | Action taken
+**   --------------------------------------------------------------------------
+**   INSERT      immediate   Increment the "immediate constraint counter".
+**
+**   DELETE      immediate   Decrement the "immediate constraint counter".
+**
+**   INSERT      deferred    Increment the "deferred constraint counter".
+**
+**   DELETE      deferred    Decrement the "deferred constraint counter".
+**
+** These operations are identified in the comment at the top of this file 
+** (fkey.c) as "I.1" and "D.1".
+*/
+static void fkLookupParent(
+  Parse *pParse,        /* Parse context */
+  int iDb,              /* Index of database housing pTab */
+  Table *pTab,          /* Parent table of FK pFKey */
+  Index *pIdx,          /* Unique index on parent key columns in pTab */
+  FKey *pFKey,          /* Foreign key constraint */
+  int *aiCol,           /* Map from parent key columns to child table columns */
+  int regData,          /* Address of array containing child table row */
+  int nIncr,            /* Increment constraint counter by this */
+  int isIgnore          /* If true, pretend pTab contains all NULL values */
+){
+  int i;                                    /* Iterator variable */
+  Vdbe *v = sqlite3GetVdbe(pParse);         /* Vdbe to add code to */
+  int iCur = pParse->nTab - 1;              /* Cursor number to use */
+  int iOk = sqlite3VdbeMakeLabel(v);        /* jump here if parent key found */
+
+  /* If nIncr is less than zero, then check at runtime if there are any
+  ** outstanding constraints to resolve. If there are not, there is no need
+  ** to check if deleting this row resolves any outstanding violations.
+  **
+  ** Check if any of the key columns in the child table row are NULL. If 
+  ** any are, then the constraint is considered satisfied. No need to 
+  ** search for a matching row in the parent table.  */
+  if( nIncr<0 ){
+    sqlite3VdbeAddOp2(v, OP_FkIfZero, pFKey->isDeferred, iOk);
+    VdbeCoverage(v);
+  }
+  for(i=0; i<pFKey->nCol; i++){
+    int iReg = aiCol[i] + regData + 1;
+    sqlite3VdbeAddOp2(v, OP_IsNull, iReg, iOk); VdbeCoverage(v);
+  }
+
+  if( isIgnore==0 ){
+    if( pIdx==0 ){
+      /* If pIdx is NULL, then the parent key is the INTEGER PRIMARY KEY
+      ** column of the parent table (table pTab).  */
+      int iMustBeInt;               /* Address of MustBeInt instruction */
+      int regTemp = sqlite3GetTempReg(pParse);
+  
+      /* Invoke MustBeInt to coerce the child key value to an integer (i.e. 
+      ** apply the affinity of the parent key). If this fails, then there
+      ** is no matching parent key. Before using MustBeInt, make a copy of
+      ** the value. Otherwise, the value inserted into the child key column
+      ** will have INTEGER affinity applied to it, which may not be correct.  */
+      sqlite3VdbeAddOp2(v, OP_SCopy, aiCol[0]+1+regData, regTemp);
+      iMustBeInt = sqlite3VdbeAddOp2(v, OP_MustBeInt, regTemp, 0);
+      VdbeCoverage(v);
+  
+      /* If the parent table is the same as the child table, and we are about
+      ** to increment the constraint-counter (i.e. this is an INSERT operation),
+      ** then check if the row being inserted matches itself. If so, do not
+      ** increment the constraint-counter.  */
+      if( pTab==pFKey->pFrom && nIncr==1 ){
+        sqlite3VdbeAddOp3(v, OP_Eq, regData, iOk, regTemp); VdbeCoverage(v);
+        sqlite3VdbeChangeP5(v, SQLITE_NOTNULL);
+      }
+  
+      sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenRead);
+      sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, regTemp); VdbeCoverage(v);
+      sqlite3VdbeGoto(v, iOk);
+      sqlite3VdbeJumpHere(v, sqlite3VdbeCurrentAddr(v)-2);
+      sqlite3VdbeJumpHere(v, iMustBeInt);
+      sqlite3ReleaseTempReg(pParse, regTemp);
+    }else{
+      int nCol = pFKey->nCol;
+      int regTemp = sqlite3GetTempRange(pParse, nCol);
+      int regRec = sqlite3GetTempReg(pParse);
+  
+      sqlite3VdbeAddOp3(v, OP_OpenRead, iCur, pIdx->tnum, iDb);
+      sqlite3VdbeSetP4KeyInfo(pParse, pIdx);
+      for(i=0; i<nCol; i++){
+        sqlite3VdbeAddOp2(v, OP_Copy, aiCol[i]+1+regData, regTemp+i);
+      }
+  
+      /* If the parent table is the same as the child table, and we are about
+      ** to increment the constraint-counter (i.e. this is an INSERT operation),
+      ** then check if the row being inserted matches itself. If so, do not
+      ** increment the constraint-counter. 
+      **
+      ** If any of the parent-key values are NULL, then the row cannot match 
+      ** itself. So set JUMPIFNULL to make sure we do the OP_Found if any
+      ** of the parent-key values are NULL (at this point it is known that
+      ** none of the child key values are).
+      */
+      if( pTab==pFKey->pFrom && nIncr==1 ){
+        int iJump = sqlite3VdbeCurrentAddr(v) + nCol + 1;
+        for(i=0; i<nCol; i++){
+          int iChild = aiCol[i]+1+regData;
+          int iParent = pIdx->aiColumn[i]+1+regData;
+          assert( pIdx->aiColumn[i]>=0 );
+          assert( aiCol[i]!=pTab->iPKey );
+          if( pIdx->aiColumn[i]==pTab->iPKey ){
+            /* The parent key is a composite key that includes the IPK column */
+            iParent = regData;
+          }
+          sqlite3VdbeAddOp3(v, OP_Ne, iChild, iJump, iParent); VdbeCoverage(v);
+          sqlite3VdbeChangeP5(v, SQLITE_JUMPIFNULL);
+        }
+        sqlite3VdbeGoto(v, iOk);
+      }
+  
+      sqlite3VdbeAddOp4(v, OP_MakeRecord, regTemp, nCol, regRec,
+                        sqlite3IndexAffinityStr(pParse->db,pIdx), nCol);
+      sqlite3VdbeAddOp4Int(v, OP_Found, iCur, iOk, regRec, 0); VdbeCoverage(v);
+  
+      sqlite3ReleaseTempReg(pParse, regRec);
+      sqlite3ReleaseTempRange(pParse, regTemp, nCol);
+    }
+  }
+
+  if( !pFKey->isDeferred && !(pParse->db->flags & SQLITE_DeferFKs)
+   && !pParse->pToplevel 
+   && !pParse->isMultiWrite 
+  ){
+    /* Special case: If this is an INSERT statement that will insert exactly
+    ** one row into the table, raise a constraint immediately instead of
+    ** incrementing a counter. This is necessary as the VM code is being
+    ** generated for will not open a statement transaction.  */
+    assert( nIncr==1 );
+    sqlite3HaltConstraint(pParse, SQLITE_CONSTRAINT_FOREIGNKEY,
+        OE_Abort, 0, P4_STATIC, P5_ConstraintFK);
+  }else{
+    if( nIncr>0 && pFKey->isDeferred==0 ){
+      sqlite3MayAbort(pParse);
+    }
+    sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, nIncr);
+  }
+
+  sqlite3VdbeResolveLabel(v, iOk);
+  sqlite3VdbeAddOp1(v, OP_Close, iCur);
+}
+
+
+/*
+** Return an Expr object that refers to a memory register corresponding
+** to column iCol of table pTab.
+**
+** regBase is the first of an array of register that contains the data
+** for pTab.  regBase itself holds the rowid.  regBase+1 holds the first
+** column.  regBase+2 holds the second column, and so forth.
+*/
+static Expr *exprTableRegister(
+  Parse *pParse,     /* Parsing and code generating context */
+  Table *pTab,       /* The table whose content is at r[regBase]... */
+  int regBase,       /* Contents of table pTab */
+  i16 iCol           /* Which column of pTab is desired */
+){
+  Expr *pExpr;
+  Column *pCol;
+  const char *zColl;
+  sqlite3 *db = pParse->db;
+
+  pExpr = sqlite3Expr(db, TK_REGISTER, 0);
+  if( pExpr ){
+    if( iCol>=0 && iCol!=pTab->iPKey ){
+      pCol = &pTab->aCol[iCol];
+      pExpr->iTable = regBase + iCol + 1;
+      pExpr->affinity = pCol->affinity;
+      zColl = pCol->zColl;
+      if( zColl==0 ) zColl = db->pDfltColl->zName;
+      pExpr = sqlite3ExprAddCollateString(pParse, pExpr, zColl);
+    }else{
+      pExpr->iTable = regBase;
+      pExpr->affinity = SQLITE_AFF_INTEGER;
+    }
+  }
+  return pExpr;
+}
+
+/*
+** Return an Expr object that refers to column iCol of table pTab which
+** has cursor iCur.
+*/
+static Expr *exprTableColumn(
+  sqlite3 *db,      /* The database connection */
+  Table *pTab,      /* The table whose column is desired */
+  int iCursor,      /* The open cursor on the table */
+  i16 iCol          /* The column that is wanted */
+){
+  Expr *pExpr = sqlite3Expr(db, TK_COLUMN, 0);
+  if( pExpr ){
+    pExpr->pTab = pTab;
+    pExpr->iTable = iCursor;
+    pExpr->iColumn = iCol;
+  }
+  return pExpr;
+}
+
+/*
+** This function is called to generate code executed when a row is deleted
+** from the parent table of foreign key constraint pFKey and, if pFKey is 
+** deferred, when a row is inserted into the same table. When generating
+** code for an SQL UPDATE operation, this function may be called twice -
+** once to "delete" the old row and once to "insert" the new row.
+**
+** Parameter nIncr is passed -1 when inserting a row (as this may decrease
+** the number of FK violations in the db) or +1 when deleting one (as this
+** may increase the number of FK constraint problems).
+**
+** The code generated by this function scans through the rows in the child
+** table that correspond to the parent table row being deleted or inserted.
+** For each child row found, one of the following actions is taken:
+**
+**   Operation | FK type   | Action taken
+**   --------------------------------------------------------------------------
+**   DELETE      immediate   Increment the "immediate constraint counter".
+**                           Or, if the ON (UPDATE|DELETE) action is RESTRICT,
+**                           throw a "FOREIGN KEY constraint failed" exception.
+**
+**   INSERT      immediate   Decrement the "immediate constraint counter".
+**
+**   DELETE      deferred    Increment the "deferred constraint counter".
+**                           Or, if the ON (UPDATE|DELETE) action is RESTRICT,
+**                           throw a "FOREIGN KEY constraint failed" exception.
+**
+**   INSERT      deferred    Decrement the "deferred constraint counter".
+**
+** These operations are identified in the comment at the top of this file 
+** (fkey.c) as "I.2" and "D.2".
+*/
+static void fkScanChildren(
+  Parse *pParse,                  /* Parse context */
+  SrcList *pSrc,                  /* The child table to be scanned */
+  Table *pTab,                    /* The parent table */
+  Index *pIdx,                    /* Index on parent covering the foreign key */
+  FKey *pFKey,                    /* The foreign key linking pSrc to pTab */
+  int *aiCol,                     /* Map from pIdx cols to child table cols */
+  int regData,                    /* Parent row data starts here */
+  int nIncr                       /* Amount to increment deferred counter by */
+){
+  sqlite3 *db = pParse->db;       /* Database handle */
+  int i;                          /* Iterator variable */
+  Expr *pWhere = 0;               /* WHERE clause to scan with */
+  NameContext sNameContext;       /* Context used to resolve WHERE clause */
+  WhereInfo *pWInfo;              /* Context used by sqlite3WhereXXX() */
+  int iFkIfZero = 0;              /* Address of OP_FkIfZero */
+  Vdbe *v = sqlite3GetVdbe(pParse);
+
+  assert( pIdx==0 || pIdx->pTable==pTab );
+  assert( pIdx==0 || pIdx->nKeyCol==pFKey->nCol );
+  assert( pIdx!=0 || pFKey->nCol==1 );
+  assert( pIdx!=0 || HasRowid(pTab) );
+
+  if( nIncr<0 ){
+    iFkIfZero = sqlite3VdbeAddOp2(v, OP_FkIfZero, pFKey->isDeferred, 0);
+    VdbeCoverage(v);
+  }
+
+  /* Create an Expr object representing an SQL expression like:
+  **
+  **   <parent-key1> = <child-key1> AND <parent-key2> = <child-key2> ...
+  **
+  ** The collation sequence used for the comparison should be that of
+  ** the parent key columns. The affinity of the parent key column should
+  ** be applied to each child key value before the comparison takes place.
+  */
+  for(i=0; i<pFKey->nCol; i++){
+    Expr *pLeft;                  /* Value from parent table row */
+    Expr *pRight;                 /* Column ref to child table */
+    Expr *pEq;                    /* Expression (pLeft = pRight) */
+    i16 iCol;                     /* Index of column in child table */ 
+    const char *zCol;             /* Name of column in child table */
+
+    iCol = pIdx ? pIdx->aiColumn[i] : -1;
+    pLeft = exprTableRegister(pParse, pTab, regData, iCol);
+    iCol = aiCol ? aiCol[i] : pFKey->aCol[0].iFrom;
+    assert( iCol>=0 );
+    zCol = pFKey->pFrom->aCol[iCol].zName;
+    pRight = sqlite3Expr(db, TK_ID, zCol);
+    pEq = sqlite3PExpr(pParse, TK_EQ, pLeft, pRight, 0);
+    pWhere = sqlite3ExprAnd(db, pWhere, pEq);
+  }
+
+  /* If the child table is the same as the parent table, then add terms
+  ** to the WHERE clause that prevent this entry from being scanned.
+  ** The added WHERE clause terms are like this:
+  **
+  **     $current_rowid!=rowid
+  **     NOT( $current_a==a AND $current_b==b AND ... )
+  **
+  ** The first form is used for rowid tables.  The second form is used
+  ** for WITHOUT ROWID tables.  In the second form, the primary key is
+  ** (a,b,...)
+  */
+  if( pTab==pFKey->pFrom && nIncr>0 ){
+    Expr *pNe;                    /* Expression (pLeft != pRight) */
+    Expr *pLeft;                  /* Value from parent table row */
+    Expr *pRight;                 /* Column ref to child table */
+    if( HasRowid(pTab) ){
+      pLeft = exprTableRegister(pParse, pTab, regData, -1);
+      pRight = exprTableColumn(db, pTab, pSrc->a[0].iCursor, -1);
+      pNe = sqlite3PExpr(pParse, TK_NE, pLeft, pRight, 0);
+    }else{
+      Expr *pEq, *pAll = 0;
+      Index *pPk = sqlite3PrimaryKeyIndex(pTab);
+      assert( pIdx!=0 );
+      for(i=0; i<pPk->nKeyCol; i++){
+        i16 iCol = pIdx->aiColumn[i];
+        assert( iCol>=0 );
+        pLeft = exprTableRegister(pParse, pTab, regData, iCol);
+        pRight = exprTableColumn(db, pTab, pSrc->a[0].iCursor, iCol);
+        pEq = sqlite3PExpr(pParse, TK_EQ, pLeft, pRight, 0);
+        pAll = sqlite3ExprAnd(db, pAll, pEq);
+      }
+      pNe = sqlite3PExpr(pParse, TK_NOT, pAll, 0, 0);
+    }
+    pWhere = sqlite3ExprAnd(db, pWhere, pNe);
+  }
+
+  /* Resolve the references in the WHERE clause. */
+  memset(&sNameContext, 0, sizeof(NameContext));
+  sNameContext.pSrcList = pSrc;
+  sNameContext.pParse = pParse;
+  sqlite3ResolveExprNames(&sNameContext, pWhere);
+
+  /* Create VDBE to loop through the entries in pSrc that match the WHERE
+  ** clause. For each row found, increment either the deferred or immediate
+  ** foreign key constraint counter. */
+  pWInfo = sqlite3WhereBegin(pParse, pSrc, pWhere, 0, 0, 0, 0);
+  sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, nIncr);
+  if( pWInfo ){
+    sqlite3WhereEnd(pWInfo);
+  }
+
+  /* Clean up the WHERE clause constructed above. */
+  sqlite3ExprDelete(db, pWhere);
+  if( iFkIfZero ){
+    sqlite3VdbeJumpHere(v, iFkIfZero);
+  }
+}
+
+/*
+** This function returns a linked list of FKey objects (connected by
+** FKey.pNextTo) holding all children of table pTab.  For example,
+** given the following schema:
+**
+**   CREATE TABLE t1(a PRIMARY KEY);
+**   CREATE TABLE t2(b REFERENCES t1(a);
+**
+** Calling this function with table "t1" as an argument returns a pointer
+** to the FKey structure representing the foreign key constraint on table
+** "t2". Calling this function with "t2" as the argument would return a
+** NULL pointer (as there are no FK constraints for which t2 is the parent
+** table).
+*/
+SQLITE_PRIVATE FKey *sqlite3FkReferences(Table *pTab){
+  return (FKey *)sqlite3HashFind(&pTab->pSchema->fkeyHash, pTab->zName);
+}
+
+/*
+** The second argument is a Trigger structure allocated by the 
+** fkActionTrigger() routine. This function deletes the Trigger structure
+** and all of its sub-components.
+**
+** The Trigger structure or any of its sub-components may be allocated from
+** the lookaside buffer belonging to database handle dbMem.
+*/
+static void fkTriggerDelete(sqlite3 *dbMem, Trigger *p){
+  if( p ){
+    TriggerStep *pStep = p->step_list;
+    sqlite3ExprDelete(dbMem, pStep->pWhere);
+    sqlite3ExprListDelete(dbMem, pStep->pExprList);
+    sqlite3SelectDelete(dbMem, pStep->pSelect);
+    sqlite3ExprDelete(dbMem, p->pWhen);
+    sqlite3DbFree(dbMem, p);
+  }
+}
+
+/*
+** This function is called to generate code that runs when table pTab is
+** being dropped from the database. The SrcList passed as the second argument
+** to this function contains a single entry guaranteed to resolve to
+** table pTab.
+**
+** Normally, no code is required. However, if either
+**
+**   (a) The table is the parent table of a FK constraint, or
+**   (b) The table is the child table of a deferred FK constraint and it is
+**       determined at runtime that there are outstanding deferred FK 
+**       constraint violations in the database,
+**
+** then the equivalent of "DELETE FROM <tbl>" is executed before dropping
+** the table from the database. Triggers are disabled while running this
+** DELETE, but foreign key actions are not.
+*/
+SQLITE_PRIVATE void sqlite3FkDropTable(Parse *pParse, SrcList *pName, Table *pTab){
+  sqlite3 *db = pParse->db;
+  if( (db->flags&SQLITE_ForeignKeys) && !IsVirtual(pTab) && !pTab->pSelect ){
+    int iSkip = 0;
+    Vdbe *v = sqlite3GetVdbe(pParse);
+
+    assert( v );                  /* VDBE has already been allocated */
+    if( sqlite3FkReferences(pTab)==0 ){
+      /* Search for a deferred foreign key constraint for which this table
+      ** is the child table. If one cannot be found, return without 
+      ** generating any VDBE code. If one can be found, then jump over
+      ** the entire DELETE if there are no outstanding deferred constraints
+      ** when this statement is run.  */
+      FKey *p;
+      for(p=pTab->pFKey; p; p=p->pNextFrom){
+        if( p->isDeferred || (db->flags & SQLITE_DeferFKs) ) break;
+      }
+      if( !p ) return;
+      iSkip = sqlite3VdbeMakeLabel(v);
+      sqlite3VdbeAddOp2(v, OP_FkIfZero, 1, iSkip); VdbeCoverage(v);
+    }
+
+    pParse->disableTriggers = 1;
+    sqlite3DeleteFrom(pParse, sqlite3SrcListDup(db, pName, 0), 0);
+    pParse->disableTriggers = 0;
+
+    /* If the DELETE has generated immediate foreign key constraint 
+    ** violations, halt the VDBE and return an error at this point, before
+    ** any modifications to the schema are made. This is because statement
+    ** transactions are not able to rollback schema changes.  
+    **
+    ** If the SQLITE_DeferFKs flag is set, then this is not required, as
+    ** the statement transaction will not be rolled back even if FK
+    ** constraints are violated.
+    */
+    if( (db->flags & SQLITE_DeferFKs)==0 ){
+      sqlite3VdbeAddOp2(v, OP_FkIfZero, 0, sqlite3VdbeCurrentAddr(v)+2);
+      VdbeCoverage(v);
+      sqlite3HaltConstraint(pParse, SQLITE_CONSTRAINT_FOREIGNKEY,
+          OE_Abort, 0, P4_STATIC, P5_ConstraintFK);
+    }
+
+    if( iSkip ){
+      sqlite3VdbeResolveLabel(v, iSkip);
+    }
+  }
+}
+
+
+/*
+** The second argument points to an FKey object representing a foreign key
+** for which pTab is the child table. An UPDATE statement against pTab
+** is currently being processed. For each column of the table that is 
+** actually updated, the corresponding element in the aChange[] array
+** is zero or greater (if a column is unmodified the corresponding element
+** is set to -1). If the rowid column is modified by the UPDATE statement
+** the bChngRowid argument is non-zero.
+**
+** This function returns true if any of the columns that are part of the
+** child key for FK constraint *p are modified.
+*/
+static int fkChildIsModified(
+  Table *pTab,                    /* Table being updated */
+  FKey *p,                        /* Foreign key for which pTab is the child */
+  int *aChange,                   /* Array indicating modified columns */
+  int bChngRowid                  /* True if rowid is modified by this update */
+){
+  int i;
+  for(i=0; i<p->nCol; i++){
+    int iChildKey = p->aCol[i].iFrom;
+    if( aChange[iChildKey]>=0 ) return 1;
+    if( iChildKey==pTab->iPKey && bChngRowid ) return 1;
+  }
+  return 0;
+}
+
+/*
+** The second argument points to an FKey object representing a foreign key
+** for which pTab is the parent table. An UPDATE statement against pTab
+** is currently being processed. For each column of the table that is 
+** actually updated, the corresponding element in the aChange[] array
+** is zero or greater (if a column is unmodified the corresponding element
+** is set to -1). If the rowid column is modified by the UPDATE statement
+** the bChngRowid argument is non-zero.
+**
+** This function returns true if any of the columns that are part of the
+** parent key for FK constraint *p are modified.
+*/
+static int fkParentIsModified(
+  Table *pTab, 
+  FKey *p, 
+  int *aChange, 
+  int bChngRowid
+){
+  int i;
+  for(i=0; i<p->nCol; i++){
+    char *zKey = p->aCol[i].zCol;
+    int iKey;
+    for(iKey=0; iKey<pTab->nCol; iKey++){
+      if( aChange[iKey]>=0 || (iKey==pTab->iPKey && bChngRowid) ){
+        Column *pCol = &pTab->aCol[iKey];
+        if( zKey ){
+          if( 0==sqlite3StrICmp(pCol->zName, zKey) ) return 1;
+        }else if( pCol->colFlags & COLFLAG_PRIMKEY ){
+          return 1;
+        }
+      }
+    }
+  }
+  return 0;
+}
+
+/*
+** Return true if the parser passed as the first argument is being
+** used to code a trigger that is really a "SET NULL" action belonging
+** to trigger pFKey.
+*/
+static int isSetNullAction(Parse *pParse, FKey *pFKey){
+  Parse *pTop = sqlite3ParseToplevel(pParse);
+  if( pTop->pTriggerPrg ){
+    Trigger *p = pTop->pTriggerPrg->pTrigger;
+    if( (p==pFKey->apTrigger[0] && pFKey->aAction[0]==OE_SetNull)
+     || (p==pFKey->apTrigger[1] && pFKey->aAction[1]==OE_SetNull)
+    ){
+      return 1;
+    }
+  }
+  return 0;
+}
+
+/*
+** This function is called when inserting, deleting or updating a row of
+** table pTab to generate VDBE code to perform foreign key constraint 
+** processing for the operation.
+**
+** For a DELETE operation, parameter regOld is passed the index of the
+** first register in an array of (pTab->nCol+1) registers containing the
+** rowid of the row being deleted, followed by each of the column values
+** of the row being deleted, from left to right. Parameter regNew is passed
+** zero in this case.
+**
+** For an INSERT operation, regOld is passed zero and regNew is passed the
+** first register of an array of (pTab->nCol+1) registers containing the new
+** row data.
+**
+** For an UPDATE operation, this function is called twice. Once before
+** the original record is deleted from the table using the calling convention
+** described for DELETE. Then again after the original record is deleted
+** but before the new record is inserted using the INSERT convention. 
+*/
+SQLITE_PRIVATE void sqlite3FkCheck(
+  Parse *pParse,                  /* Parse context */
+  Table *pTab,                    /* Row is being deleted from this table */ 
+  int regOld,                     /* Previous row data is stored here */
+  int regNew,                     /* New row data is stored here */
+  int *aChange,                   /* Array indicating UPDATEd columns (or 0) */
+  int bChngRowid                  /* True if rowid is UPDATEd */
+){
+  sqlite3 *db = pParse->db;       /* Database handle */
+  FKey *pFKey;                    /* Used to iterate through FKs */
+  int iDb;                        /* Index of database containing pTab */
+  const char *zDb;                /* Name of database containing pTab */
+  int isIgnoreErrors = pParse->disableTriggers;
+
+  /* Exactly one of regOld and regNew should be non-zero. */
+  assert( (regOld==0)!=(regNew==0) );
+
+  /* If foreign-keys are disabled, this function is a no-op. */
+  if( (db->flags&SQLITE_ForeignKeys)==0 ) return;
+
+  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+  zDb = db->aDb[iDb].zDbSName;
+
+  /* Loop through all the foreign key constraints for which pTab is the
+  ** child table (the table that the foreign key definition is part of).  */
+  for(pFKey=pTab->pFKey; pFKey; pFKey=pFKey->pNextFrom){
+    Table *pTo;                   /* Parent table of foreign key pFKey */
+    Index *pIdx = 0;              /* Index on key columns in pTo */
+    int *aiFree = 0;
+    int *aiCol;
+    int iCol;
+    int i;
+    int bIgnore = 0;
+
+    if( aChange 
+     && sqlite3_stricmp(pTab->zName, pFKey->zTo)!=0
+     && fkChildIsModified(pTab, pFKey, aChange, bChngRowid)==0 
+    ){
+      continue;
+    }
+
+    /* Find the parent table of this foreign key. Also find a unique index 
+    ** on the parent key columns in the parent table. If either of these 
+    ** schema items cannot be located, set an error in pParse and return 
+    ** early.  */
+    if( pParse->disableTriggers ){
+      pTo = sqlite3FindTable(db, pFKey->zTo, zDb);
+    }else{
+      pTo = sqlite3LocateTable(pParse, 0, pFKey->zTo, zDb);
+    }
+    if( !pTo || sqlite3FkLocateIndex(pParse, pTo, pFKey, &pIdx, &aiFree) ){
+      assert( isIgnoreErrors==0 || (regOld!=0 && regNew==0) );
+      if( !isIgnoreErrors || db->mallocFailed ) return;
+      if( pTo==0 ){
+        /* If isIgnoreErrors is true, then a table is being dropped. In this
+        ** case SQLite runs a "DELETE FROM xxx" on the table being dropped
+        ** before actually dropping it in order to check FK constraints.
+        ** If the parent table of an FK constraint on the current table is
+        ** missing, behave as if it is empty. i.e. decrement the relevant
+        ** FK counter for each row of the current table with non-NULL keys.
+        */
+        Vdbe *v = sqlite3GetVdbe(pParse);
+        int iJump = sqlite3VdbeCurrentAddr(v) + pFKey->nCol + 1;
+        for(i=0; i<pFKey->nCol; i++){
+          int iReg = pFKey->aCol[i].iFrom + regOld + 1;
+          sqlite3VdbeAddOp2(v, OP_IsNull, iReg, iJump); VdbeCoverage(v);
+        }
+        sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, -1);
+      }
+      continue;
+    }
+    assert( pFKey->nCol==1 || (aiFree && pIdx) );
+
+    if( aiFree ){
+      aiCol = aiFree;
+    }else{
+      iCol = pFKey->aCol[0].iFrom;
+      aiCol = &iCol;
+    }
+    for(i=0; i<pFKey->nCol; i++){
+      if( aiCol[i]==pTab->iPKey ){
+        aiCol[i] = -1;
+      }
+      assert( pIdx==0 || pIdx->aiColumn[i]>=0 );
+#ifndef SQLITE_OMIT_AUTHORIZATION
+      /* Request permission to read the parent key columns. If the 
+      ** authorization callback returns SQLITE_IGNORE, behave as if any
+      ** values read from the parent table are NULL. */
+      if( db->xAuth ){
+        int rcauth;
+        char *zCol = pTo->aCol[pIdx ? pIdx->aiColumn[i] : pTo->iPKey].zName;
+        rcauth = sqlite3AuthReadCol(pParse, pTo->zName, zCol, iDb);
+        bIgnore = (rcauth==SQLITE_IGNORE);
+      }
+#endif
+    }
+
+    /* Take a shared-cache advisory read-lock on the parent table. Allocate 
+    ** a cursor to use to search the unique index on the parent key columns 
+    ** in the parent table.  */
+    sqlite3TableLock(pParse, iDb, pTo->tnum, 0, pTo->zName);
+    pParse->nTab++;
+
+    if( regOld!=0 ){
+      /* A row is being removed from the child table. Search for the parent.
+      ** If the parent does not exist, removing the child row resolves an 
+      ** outstanding foreign key constraint violation. */
+      fkLookupParent(pParse, iDb, pTo, pIdx, pFKey, aiCol, regOld, -1, bIgnore);
+    }
+    if( regNew!=0 && !isSetNullAction(pParse, pFKey) ){
+      /* A row is being added to the child table. If a parent row cannot
+      ** be found, adding the child row has violated the FK constraint. 
+      **
+      ** If this operation is being performed as part of a trigger program
+      ** that is actually a "SET NULL" action belonging to this very 
+      ** foreign key, then omit this scan altogether. As all child key
+      ** values are guaranteed to be NULL, it is not possible for adding
+      ** this row to cause an FK violation.  */
+      fkLookupParent(pParse, iDb, pTo, pIdx, pFKey, aiCol, regNew, +1, bIgnore);
+    }
+
+    sqlite3DbFree(db, aiFree);
+  }
+
+  /* Loop through all the foreign key constraints that refer to this table.
+  ** (the "child" constraints) */
+  for(pFKey = sqlite3FkReferences(pTab); pFKey; pFKey=pFKey->pNextTo){
+    Index *pIdx = 0;              /* Foreign key index for pFKey */
+    SrcList *pSrc;
+    int *aiCol = 0;
+
+    if( aChange && fkParentIsModified(pTab, pFKey, aChange, bChngRowid)==0 ){
+      continue;
+    }
+
+    if( !pFKey->isDeferred && !(db->flags & SQLITE_DeferFKs) 
+     && !pParse->pToplevel && !pParse->isMultiWrite 
+    ){
+      assert( regOld==0 && regNew!=0 );
+      /* Inserting a single row into a parent table cannot cause (or fix)
+      ** an immediate foreign key violation. So do nothing in this case.  */
+      continue;
+    }
+
+    if( sqlite3FkLocateIndex(pParse, pTab, pFKey, &pIdx, &aiCol) ){
+      if( !isIgnoreErrors || db->mallocFailed ) return;
+      continue;
+    }
+    assert( aiCol || pFKey->nCol==1 );
+
+    /* Create a SrcList structure containing the child table.  We need the
+    ** child table as a SrcList for sqlite3WhereBegin() */
+    pSrc = sqlite3SrcListAppend(db, 0, 0, 0);
+    if( pSrc ){
+      struct SrcList_item *pItem = pSrc->a;
+      pItem->pTab = pFKey->pFrom;
+      pItem->zName = pFKey->pFrom->zName;
+      pItem->pTab->nRef++;
+      pItem->iCursor = pParse->nTab++;
+  
+      if( regNew!=0 ){
+        fkScanChildren(pParse, pSrc, pTab, pIdx, pFKey, aiCol, regNew, -1);
+      }
+      if( regOld!=0 ){
+        int eAction = pFKey->aAction[aChange!=0];
+        fkScanChildren(pParse, pSrc, pTab, pIdx, pFKey, aiCol, regOld, 1);
+        /* If this is a deferred FK constraint, or a CASCADE or SET NULL
+        ** action applies, then any foreign key violations caused by
+        ** removing the parent key will be rectified by the action trigger.
+        ** So do not set the "may-abort" flag in this case.
+        **
+        ** Note 1: If the FK is declared "ON UPDATE CASCADE", then the
+        ** may-abort flag will eventually be set on this statement anyway
+        ** (when this function is called as part of processing the UPDATE
+        ** within the action trigger).
+        **
+        ** Note 2: At first glance it may seem like SQLite could simply omit
+        ** all OP_FkCounter related scans when either CASCADE or SET NULL
+        ** applies. The trouble starts if the CASCADE or SET NULL action 
+        ** trigger causes other triggers or action rules attached to the 
+        ** child table to fire. In these cases the fk constraint counters
+        ** might be set incorrectly if any OP_FkCounter related scans are 
+        ** omitted.  */
+        if( !pFKey->isDeferred && eAction!=OE_Cascade && eAction!=OE_SetNull ){
+          sqlite3MayAbort(pParse);
+        }
+      }
+      pItem->zName = 0;
+      sqlite3SrcListDelete(db, pSrc);
+    }
+    sqlite3DbFree(db, aiCol);
+  }
+}
+
+#define COLUMN_MASK(x) (((x)>31) ? 0xffffffff : ((u32)1<<(x)))
+
+/*
+** This function is called before generating code to update or delete a 
+** row contained in table pTab.
+*/
+SQLITE_PRIVATE u32 sqlite3FkOldmask(
+  Parse *pParse,                  /* Parse context */
+  Table *pTab                     /* Table being modified */
+){
+  u32 mask = 0;
+  if( pParse->db->flags&SQLITE_ForeignKeys ){
+    FKey *p;
+    int i;
+    for(p=pTab->pFKey; p; p=p->pNextFrom){
+      for(i=0; i<p->nCol; i++) mask |= COLUMN_MASK(p->aCol[i].iFrom);
+    }
+    for(p=sqlite3FkReferences(pTab); p; p=p->pNextTo){
+      Index *pIdx = 0;
+      sqlite3FkLocateIndex(pParse, pTab, p, &pIdx, 0);
+      if( pIdx ){
+        for(i=0; i<pIdx->nKeyCol; i++){
+          assert( pIdx->aiColumn[i]>=0 );
+          mask |= COLUMN_MASK(pIdx->aiColumn[i]);
+        }
+      }
+    }
+  }
+  return mask;
+}
+
+
+/*
+** This function is called before generating code to update or delete a 
+** row contained in table pTab. If the operation is a DELETE, then
+** parameter aChange is passed a NULL value. For an UPDATE, aChange points
+** to an array of size N, where N is the number of columns in table pTab.
+** If the i'th column is not modified by the UPDATE, then the corresponding 
+** entry in the aChange[] array is set to -1. If the column is modified,
+** the value is 0 or greater. Parameter chngRowid is set to true if the
+** UPDATE statement modifies the rowid fields of the table.
+**
+** If any foreign key processing will be required, this function returns
+** true. If there is no foreign key related processing, this function 
+** returns false.
+*/
+SQLITE_PRIVATE int sqlite3FkRequired(
+  Parse *pParse,                  /* Parse context */
+  Table *pTab,                    /* Table being modified */
+  int *aChange,                   /* Non-NULL for UPDATE operations */
+  int chngRowid                   /* True for UPDATE that affects rowid */
+){
+  if( pParse->db->flags&SQLITE_ForeignKeys ){
+    if( !aChange ){
+      /* A DELETE operation. Foreign key processing is required if the 
+      ** table in question is either the child or parent table for any 
+      ** foreign key constraint.  */
+      return (sqlite3FkReferences(pTab) || pTab->pFKey);
+    }else{
+      /* This is an UPDATE. Foreign key processing is only required if the
+      ** operation modifies one or more child or parent key columns. */
+      FKey *p;
+
+      /* Check if any child key columns are being modified. */
+      for(p=pTab->pFKey; p; p=p->pNextFrom){
+        if( fkChildIsModified(pTab, p, aChange, chngRowid) ) return 1;
+      }
+
+      /* Check if any parent key columns are being modified. */
+      for(p=sqlite3FkReferences(pTab); p; p=p->pNextTo){
+        if( fkParentIsModified(pTab, p, aChange, chngRowid) ) return 1;
+      }
+    }
+  }
+  return 0;
+}
+
+/*
+** This function is called when an UPDATE or DELETE operation is being 
+** compiled on table pTab, which is the parent table of foreign-key pFKey.
+** If the current operation is an UPDATE, then the pChanges parameter is
+** passed a pointer to the list of columns being modified. If it is a
+** DELETE, pChanges is passed a NULL pointer.
+**
+** It returns a pointer to a Trigger structure containing a trigger
+** equivalent to the ON UPDATE or ON DELETE action specified by pFKey.
+** If the action is "NO ACTION" or "RESTRICT", then a NULL pointer is
+** returned (these actions require no special handling by the triggers
+** sub-system, code for them is created by fkScanChildren()).
+**
+** For example, if pFKey is the foreign key and pTab is table "p" in 
+** the following schema:
+**
+**   CREATE TABLE p(pk PRIMARY KEY);
+**   CREATE TABLE c(ck REFERENCES p ON DELETE CASCADE);
+**
+** then the returned trigger structure is equivalent to:
+**
+**   CREATE TRIGGER ... DELETE ON p BEGIN
+**     DELETE FROM c WHERE ck = old.pk;
+**   END;
+**
+** The returned pointer is cached as part of the foreign key object. It
+** is eventually freed along with the rest of the foreign key object by 
+** sqlite3FkDelete().
+*/
+static Trigger *fkActionTrigger(
+  Parse *pParse,                  /* Parse context */
+  Table *pTab,                    /* Table being updated or deleted from */
+  FKey *pFKey,                    /* Foreign key to get action for */
+  ExprList *pChanges              /* Change-list for UPDATE, NULL for DELETE */
+){
+  sqlite3 *db = pParse->db;       /* Database handle */
+  int action;                     /* One of OE_None, OE_Cascade etc. */
+  Trigger *pTrigger;              /* Trigger definition to return */
+  int iAction = (pChanges!=0);    /* 1 for UPDATE, 0 for DELETE */
+
+  action = pFKey->aAction[iAction];
+  if( action==OE_Restrict && (db->flags & SQLITE_DeferFKs) ){
+    return 0;
+  }
+  pTrigger = pFKey->apTrigger[iAction];
+
+  if( action!=OE_None && !pTrigger ){
+    char const *zFrom;            /* Name of child table */
+    int nFrom;                    /* Length in bytes of zFrom */
+    Index *pIdx = 0;              /* Parent key index for this FK */
+    int *aiCol = 0;               /* child table cols -> parent key cols */
+    TriggerStep *pStep = 0;        /* First (only) step of trigger program */
+    Expr *pWhere = 0;             /* WHERE clause of trigger step */
+    ExprList *pList = 0;          /* Changes list if ON UPDATE CASCADE */
+    Select *pSelect = 0;          /* If RESTRICT, "SELECT RAISE(...)" */
+    int i;                        /* Iterator variable */
+    Expr *pWhen = 0;              /* WHEN clause for the trigger */
+
+    if( sqlite3FkLocateIndex(pParse, pTab, pFKey, &pIdx, &aiCol) ) return 0;
+    assert( aiCol || pFKey->nCol==1 );
+
+    for(i=0; i<pFKey->nCol; i++){
+      Token tOld = { "old", 3 };  /* Literal "old" token */
+      Token tNew = { "new", 3 };  /* Literal "new" token */
+      Token tFromCol;             /* Name of column in child table */
+      Token tToCol;               /* Name of column in parent table */
+      int iFromCol;               /* Idx of column in child table */
+      Expr *pEq;                  /* tFromCol = OLD.tToCol */
+
+      iFromCol = aiCol ? aiCol[i] : pFKey->aCol[0].iFrom;
+      assert( iFromCol>=0 );
+      assert( pIdx!=0 || (pTab->iPKey>=0 && pTab->iPKey<pTab->nCol) );
+      assert( pIdx==0 || pIdx->aiColumn[i]>=0 );
+      sqlite3TokenInit(&tToCol,
+                   pTab->aCol[pIdx ? pIdx->aiColumn[i] : pTab->iPKey].zName);
+      sqlite3TokenInit(&tFromCol, pFKey->pFrom->aCol[iFromCol].zName);
+
+      /* Create the expression "OLD.zToCol = zFromCol". It is important
+      ** that the "OLD.zToCol" term is on the LHS of the = operator, so
+      ** that the affinity and collation sequence associated with the
+      ** parent table are used for the comparison. */
+      pEq = sqlite3PExpr(pParse, TK_EQ,
+          sqlite3PExpr(pParse, TK_DOT, 
+            sqlite3ExprAlloc(db, TK_ID, &tOld, 0),
+            sqlite3ExprAlloc(db, TK_ID, &tToCol, 0)
+          , 0),
+          sqlite3ExprAlloc(db, TK_ID, &tFromCol, 0)
+      , 0);
+      pWhere = sqlite3ExprAnd(db, pWhere, pEq);
+
+      /* For ON UPDATE, construct the next term of the WHEN clause.
+      ** The final WHEN clause will be like this:
+      **
+      **    WHEN NOT(old.col1 IS new.col1 AND ... AND old.colN IS new.colN)
+      */
+      if( pChanges ){
+        pEq = sqlite3PExpr(pParse, TK_IS,
+            sqlite3PExpr(pParse, TK_DOT, 
+              sqlite3ExprAlloc(db, TK_ID, &tOld, 0),
+              sqlite3ExprAlloc(db, TK_ID, &tToCol, 0),
+              0),
+            sqlite3PExpr(pParse, TK_DOT, 
+              sqlite3ExprAlloc(db, TK_ID, &tNew, 0),
+              sqlite3ExprAlloc(db, TK_ID, &tToCol, 0),
+              0),
+            0);
+        pWhen = sqlite3ExprAnd(db, pWhen, pEq);
+      }
+  
+      if( action!=OE_Restrict && (action!=OE_Cascade || pChanges) ){
+        Expr *pNew;
+        if( action==OE_Cascade ){
+          pNew = sqlite3PExpr(pParse, TK_DOT, 
+            sqlite3ExprAlloc(db, TK_ID, &tNew, 0),
+            sqlite3ExprAlloc(db, TK_ID, &tToCol, 0)
+          , 0);
+        }else if( action==OE_SetDflt ){
+          Expr *pDflt = pFKey->pFrom->aCol[iFromCol].pDflt;
+          if( pDflt ){
+            pNew = sqlite3ExprDup(db, pDflt, 0);
+          }else{
+            pNew = sqlite3ExprAlloc(db, TK_NULL, 0, 0);
+          }
+        }else{
+          pNew = sqlite3ExprAlloc(db, TK_NULL, 0, 0);
+        }
+        pList = sqlite3ExprListAppend(pParse, pList, pNew);
+        sqlite3ExprListSetName(pParse, pList, &tFromCol, 0);
+      }
+    }
+    sqlite3DbFree(db, aiCol);
+
+    zFrom = pFKey->pFrom->zName;
+    nFrom = sqlite3Strlen30(zFrom);
+
+    if( action==OE_Restrict ){
+      Token tFrom;
+      Expr *pRaise; 
+
+      tFrom.z = zFrom;
+      tFrom.n = nFrom;
+      pRaise = sqlite3Expr(db, TK_RAISE, "FOREIGN KEY constraint failed");
+      if( pRaise ){
+        pRaise->affinity = OE_Abort;
+      }
+      pSelect = sqlite3SelectNew(pParse, 
+          sqlite3ExprListAppend(pParse, 0, pRaise),
+          sqlite3SrcListAppend(db, 0, &tFrom, 0),
+          pWhere,
+          0, 0, 0, 0, 0, 0
+      );
+      pWhere = 0;
+    }
+
+    /* Disable lookaside memory allocation */
+    db->lookaside.bDisable++;
+
+    pTrigger = (Trigger *)sqlite3DbMallocZero(db, 
+        sizeof(Trigger) +         /* struct Trigger */
+        sizeof(TriggerStep) +     /* Single step in trigger program */
+        nFrom + 1                 /* Space for pStep->zTarget */
+    );
+    if( pTrigger ){
+      pStep = pTrigger->step_list = (TriggerStep *)&pTrigger[1];
+      pStep->zTarget = (char *)&pStep[1];
+      memcpy((char *)pStep->zTarget, zFrom, nFrom);
+  
+      pStep->pWhere = sqlite3ExprDup(db, pWhere, EXPRDUP_REDUCE);
+      pStep->pExprList = sqlite3ExprListDup(db, pList, EXPRDUP_REDUCE);
+      pStep->pSelect = sqlite3SelectDup(db, pSelect, EXPRDUP_REDUCE);
+      if( pWhen ){
+        pWhen = sqlite3PExpr(pParse, TK_NOT, pWhen, 0, 0);
+        pTrigger->pWhen = sqlite3ExprDup(db, pWhen, EXPRDUP_REDUCE);
+      }
+    }
+
+    /* Re-enable the lookaside buffer, if it was disabled earlier. */
+    db->lookaside.bDisable--;
+
+    sqlite3ExprDelete(db, pWhere);
+    sqlite3ExprDelete(db, pWhen);
+    sqlite3ExprListDelete(db, pList);
+    sqlite3SelectDelete(db, pSelect);
+    if( db->mallocFailed==1 ){
+      fkTriggerDelete(db, pTrigger);
+      return 0;
+    }
+    assert( pStep!=0 );
+
+    switch( action ){
+      case OE_Restrict:
+        pStep->op = TK_SELECT; 
+        break;
+      case OE_Cascade: 
+        if( !pChanges ){ 
+          pStep->op = TK_DELETE; 
+          break; 
+        }
+      default:
+        pStep->op = TK_UPDATE;
+    }
+    pStep->pTrig = pTrigger;
+    pTrigger->pSchema = pTab->pSchema;
+    pTrigger->pTabSchema = pTab->pSchema;
+    pFKey->apTrigger[iAction] = pTrigger;
+    pTrigger->op = (pChanges ? TK_UPDATE : TK_DELETE);
+  }
+
+  return pTrigger;
+}
+
+/*
+** This function is called when deleting or updating a row to implement
+** any required CASCADE, SET NULL or SET DEFAULT actions.
+*/
+SQLITE_PRIVATE void sqlite3FkActions(
+  Parse *pParse,                  /* Parse context */
+  Table *pTab,                    /* Table being updated or deleted from */
+  ExprList *pChanges,             /* Change-list for UPDATE, NULL for DELETE */
+  int regOld,                     /* Address of array containing old row */
+  int *aChange,                   /* Array indicating UPDATEd columns (or 0) */
+  int bChngRowid                  /* True if rowid is UPDATEd */
+){
+  /* If foreign-key support is enabled, iterate through all FKs that 
+  ** refer to table pTab. If there is an action associated with the FK 
+  ** for this operation (either update or delete), invoke the associated 
+  ** trigger sub-program.  */
+  if( pParse->db->flags&SQLITE_ForeignKeys ){
+    FKey *pFKey;                  /* Iterator variable */
+    for(pFKey = sqlite3FkReferences(pTab); pFKey; pFKey=pFKey->pNextTo){
+      if( aChange==0 || fkParentIsModified(pTab, pFKey, aChange, bChngRowid) ){
+        Trigger *pAct = fkActionTrigger(pParse, pTab, pFKey, pChanges);
+        if( pAct ){
+          sqlite3CodeRowTriggerDirect(pParse, pAct, pTab, regOld, OE_Abort, 0);
+        }
+      }
+    }
+  }
+}
+
+#endif /* ifndef SQLITE_OMIT_TRIGGER */
+
+/*
+** Free all memory associated with foreign key definitions attached to
+** table pTab. Remove the deleted foreign keys from the Schema.fkeyHash
+** hash table.
+*/
+SQLITE_PRIVATE void sqlite3FkDelete(sqlite3 *db, Table *pTab){
+  FKey *pFKey;                    /* Iterator variable */
+  FKey *pNext;                    /* Copy of pFKey->pNextFrom */
+
+  assert( db==0 || IsVirtual(pTab)
+         || sqlite3SchemaMutexHeld(db, 0, pTab->pSchema) );
+  for(pFKey=pTab->pFKey; pFKey; pFKey=pNext){
+
+    /* Remove the FK from the fkeyHash hash table. */
+    if( !db || db->pnBytesFreed==0 ){
+      if( pFKey->pPrevTo ){
+        pFKey->pPrevTo->pNextTo = pFKey->pNextTo;
+      }else{
+        void *p = (void *)pFKey->pNextTo;
+        const char *z = (p ? pFKey->pNextTo->zTo : pFKey->zTo);
+        sqlite3HashInsert(&pTab->pSchema->fkeyHash, z, p);
+      }
+      if( pFKey->pNextTo ){
+        pFKey->pNextTo->pPrevTo = pFKey->pPrevTo;
+      }
+    }
+
+    /* EV: R-30323-21917 Each foreign key constraint in SQLite is
+    ** classified as either immediate or deferred.
+    */
+    assert( pFKey->isDeferred==0 || pFKey->isDeferred==1 );
+
+    /* Delete any triggers created to implement actions for this FK. */
+#ifndef SQLITE_OMIT_TRIGGER
+    fkTriggerDelete(db, pFKey->apTrigger[0]);
+    fkTriggerDelete(db, pFKey->apTrigger[1]);
+#endif
+
+    pNext = pFKey->pNextFrom;
+    sqlite3DbFree(db, pFKey);
+  }
+}
+#endif /* ifndef SQLITE_OMIT_FOREIGN_KEY */
+
+/************** End of fkey.c ************************************************/
+/************** Begin file insert.c ******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains C code routines that are called by the parser
+** to handle INSERT statements in SQLite.
+*/
+/* #include "sqliteInt.h" */
+
+/*
+** Generate code that will 
+**
+**   (1) acquire a lock for table pTab then
+**   (2) open pTab as cursor iCur.
+**
+** If pTab is a WITHOUT ROWID table, then it is the PRIMARY KEY index
+** for that table that is actually opened.
+*/
+SQLITE_PRIVATE void sqlite3OpenTable(
+  Parse *pParse,  /* Generate code into this VDBE */
+  int iCur,       /* The cursor number of the table */
+  int iDb,        /* The database index in sqlite3.aDb[] */
+  Table *pTab,    /* The table to be opened */
+  int opcode      /* OP_OpenRead or OP_OpenWrite */
+){
+  Vdbe *v;
+  assert( !IsVirtual(pTab) );
+  v = sqlite3GetVdbe(pParse);
+  assert( opcode==OP_OpenWrite || opcode==OP_OpenRead );
+  sqlite3TableLock(pParse, iDb, pTab->tnum, 
+                   (opcode==OP_OpenWrite)?1:0, pTab->zName);
+  if( HasRowid(pTab) ){
+    sqlite3VdbeAddOp4Int(v, opcode, iCur, pTab->tnum, iDb, pTab->nCol);
+    VdbeComment((v, "%s", pTab->zName));
+  }else{
+    Index *pPk = sqlite3PrimaryKeyIndex(pTab);
+    assert( pPk!=0 );
+    assert( pPk->tnum==pTab->tnum );
+    sqlite3VdbeAddOp3(v, opcode, iCur, pPk->tnum, iDb);
+    sqlite3VdbeSetP4KeyInfo(pParse, pPk);
+    VdbeComment((v, "%s", pTab->zName));
+  }
+}
+
+/*
+** Return a pointer to the column affinity string associated with index
+** pIdx. A column affinity string has one character for each column in 
+** the table, according to the affinity of the column:
+**
+**  Character      Column affinity
+**  ------------------------------
+**  'A'            BLOB
+**  'B'            TEXT
+**  'C'            NUMERIC
+**  'D'            INTEGER
+**  'F'            REAL
+**
+** An extra 'D' is appended to the end of the string to cover the
+** rowid that appears as the last column in every index.
+**
+** Memory for the buffer containing the column index affinity string
+** is managed along with the rest of the Index structure. It will be
+** released when sqlite3DeleteIndex() is called.
+*/
+SQLITE_PRIVATE const char *sqlite3IndexAffinityStr(sqlite3 *db, Index *pIdx){
+  if( !pIdx->zColAff ){
+    /* The first time a column affinity string for a particular index is
+    ** required, it is allocated and populated here. It is then stored as
+    ** a member of the Index structure for subsequent use.
+    **
+    ** The column affinity string will eventually be deleted by
+    ** sqliteDeleteIndex() when the Index structure itself is cleaned
+    ** up.
+    */
+    int n;
+    Table *pTab = pIdx->pTable;
+    pIdx->zColAff = (char *)sqlite3DbMallocRaw(0, pIdx->nColumn+1);
+    if( !pIdx->zColAff ){
+      sqlite3OomFault(db);
+      return 0;
+    }
+    for(n=0; n<pIdx->nColumn; n++){
+      i16 x = pIdx->aiColumn[n];
+      if( x>=0 ){
+        pIdx->zColAff[n] = pTab->aCol[x].affinity;
+      }else if( x==XN_ROWID ){
+        pIdx->zColAff[n] = SQLITE_AFF_INTEGER;
+      }else{
+        char aff;
+        assert( x==XN_EXPR );
+        assert( pIdx->aColExpr!=0 );
+        aff = sqlite3ExprAffinity(pIdx->aColExpr->a[n].pExpr);
+        if( aff==0 ) aff = SQLITE_AFF_BLOB;
+        pIdx->zColAff[n] = aff;
+      }
+    }
+    pIdx->zColAff[n] = 0;
+  }
+ 
+  return pIdx->zColAff;
+}
+
+/*
+** Compute the affinity string for table pTab, if it has not already been
+** computed.  As an optimization, omit trailing SQLITE_AFF_BLOB affinities.
+**
+** If the affinity exists (if it is no entirely SQLITE_AFF_BLOB values) and
+** if iReg>0 then code an OP_Affinity opcode that will set the affinities
+** for register iReg and following.  Or if affinities exists and iReg==0,
+** then just set the P4 operand of the previous opcode (which should  be
+** an OP_MakeRecord) to the affinity string.
+**
+** A column affinity string has one character per column:
+**
+**  Character      Column affinity
+**  ------------------------------
+**  'A'            BLOB
+**  'B'            TEXT
+**  'C'            NUMERIC
+**  'D'            INTEGER
+**  'E'            REAL
+*/
+SQLITE_PRIVATE void sqlite3TableAffinity(Vdbe *v, Table *pTab, int iReg){
+  int i;
+  char *zColAff = pTab->zColAff;
+  if( zColAff==0 ){
+    sqlite3 *db = sqlite3VdbeDb(v);
+    zColAff = (char *)sqlite3DbMallocRaw(0, pTab->nCol+1);
+    if( !zColAff ){
+      sqlite3OomFault(db);
+      return;
+    }
+
+    for(i=0; i<pTab->nCol; i++){
+      zColAff[i] = pTab->aCol[i].affinity;
+    }
+    do{
+      zColAff[i--] = 0;
+    }while( i>=0 && zColAff[i]==SQLITE_AFF_BLOB );
+    pTab->zColAff = zColAff;
+  }
+  i = sqlite3Strlen30(zColAff);
+  if( i ){
+    if( iReg ){
+      sqlite3VdbeAddOp4(v, OP_Affinity, iReg, i, 0, zColAff, i);
+    }else{
+      sqlite3VdbeChangeP4(v, -1, zColAff, i);
+    }
+  }
+}
+
+/*
+** Return non-zero if the table pTab in database iDb or any of its indices
+** have been opened at any point in the VDBE program. This is used to see if 
+** a statement of the form  "INSERT INTO <iDb, pTab> SELECT ..." can 
+** run without using a temporary table for the results of the SELECT. 
+*/
+static int readsTable(Parse *p, int iDb, Table *pTab){
+  Vdbe *v = sqlite3GetVdbe(p);
+  int i;
+  int iEnd = sqlite3VdbeCurrentAddr(v);
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  VTable *pVTab = IsVirtual(pTab) ? sqlite3GetVTable(p->db, pTab) : 0;
+#endif
+
+  for(i=1; i<iEnd; i++){
+    VdbeOp *pOp = sqlite3VdbeGetOp(v, i);
+    assert( pOp!=0 );
+    if( pOp->opcode==OP_OpenRead && pOp->p3==iDb ){
+      Index *pIndex;
+      int tnum = pOp->p2;
+      if( tnum==pTab->tnum ){
+        return 1;
+      }
+      for(pIndex=pTab->pIndex; pIndex; pIndex=pIndex->pNext){
+        if( tnum==pIndex->tnum ){
+          return 1;
+        }
+      }
+    }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    if( pOp->opcode==OP_VOpen && pOp->p4.pVtab==pVTab ){
+      assert( pOp->p4.pVtab!=0 );
+      assert( pOp->p4type==P4_VTAB );
+      return 1;
+    }
+#endif
+  }
+  return 0;
+}
+
+#ifndef SQLITE_OMIT_AUTOINCREMENT
+/*
+** Locate or create an AutoincInfo structure associated with table pTab
+** which is in database iDb.  Return the register number for the register
+** that holds the maximum rowid.  Return zero if pTab is not an AUTOINCREMENT
+** table.  (Also return zero when doing a VACUUM since we do not want to
+** update the AUTOINCREMENT counters during a VACUUM.)
+**
+** There is at most one AutoincInfo structure per table even if the
+** same table is autoincremented multiple times due to inserts within
+** triggers.  A new AutoincInfo structure is created if this is the
+** first use of table pTab.  On 2nd and subsequent uses, the original
+** AutoincInfo structure is used.
+**
+** Three memory locations are allocated:
+**
+**   (1)  Register to hold the name of the pTab table.
+**   (2)  Register to hold the maximum ROWID of pTab.
+**   (3)  Register to hold the rowid in sqlite_sequence of pTab
+**
+** The 2nd register is the one that is returned.  That is all the
+** insert routine needs to know about.
+*/
+static int autoIncBegin(
+  Parse *pParse,      /* Parsing context */
+  int iDb,            /* Index of the database holding pTab */
+  Table *pTab         /* The table we are writing to */
+){
+  int memId = 0;      /* Register holding maximum rowid */
+  if( (pTab->tabFlags & TF_Autoincrement)!=0
+   && (pParse->db->flags & SQLITE_Vacuum)==0
+  ){
+    Parse *pToplevel = sqlite3ParseToplevel(pParse);
+    AutoincInfo *pInfo;
+
+    pInfo = pToplevel->pAinc;
+    while( pInfo && pInfo->pTab!=pTab ){ pInfo = pInfo->pNext; }
+    if( pInfo==0 ){
+      pInfo = sqlite3DbMallocRawNN(pParse->db, sizeof(*pInfo));
+      if( pInfo==0 ) return 0;
+      pInfo->pNext = pToplevel->pAinc;
+      pToplevel->pAinc = pInfo;
+      pInfo->pTab = pTab;
+      pInfo->iDb = iDb;
+      pToplevel->nMem++;                  /* Register to hold name of table */
+      pInfo->regCtr = ++pToplevel->nMem;  /* Max rowid register */
+      pToplevel->nMem++;                  /* Rowid in sqlite_sequence */
+    }
+    memId = pInfo->regCtr;
+  }
+  return memId;
+}
+
+/*
+** This routine generates code that will initialize all of the
+** register used by the autoincrement tracker.  
+*/
+SQLITE_PRIVATE void sqlite3AutoincrementBegin(Parse *pParse){
+  AutoincInfo *p;            /* Information about an AUTOINCREMENT */
+  sqlite3 *db = pParse->db;  /* The database connection */
+  Db *pDb;                   /* Database only autoinc table */
+  int memId;                 /* Register holding max rowid */
+  Vdbe *v = pParse->pVdbe;   /* VDBE under construction */
+
+  /* This routine is never called during trigger-generation.  It is
+  ** only called from the top-level */
+  assert( pParse->pTriggerTab==0 );
+  assert( sqlite3IsToplevel(pParse) );
+
+  assert( v );   /* We failed long ago if this is not so */
+  for(p = pParse->pAinc; p; p = p->pNext){
+    static const int iLn = VDBE_OFFSET_LINENO(2);
+    static const VdbeOpList autoInc[] = {
+      /* 0  */ {OP_Null,    0,  0, 0},
+      /* 1  */ {OP_Rewind,  0,  9, 0},
+      /* 2  */ {OP_Column,  0,  0, 0},
+      /* 3  */ {OP_Ne,      0,  7, 0},
+      /* 4  */ {OP_Rowid,   0,  0, 0},
+      /* 5  */ {OP_Column,  0,  1, 0},
+      /* 6  */ {OP_Goto,    0,  9, 0},
+      /* 7  */ {OP_Next,    0,  2, 0},
+      /* 8  */ {OP_Integer, 0,  0, 0},
+      /* 9  */ {OP_Close,   0,  0, 0} 
+    };
+    VdbeOp *aOp;
+    pDb = &db->aDb[p->iDb];
+    memId = p->regCtr;
+    assert( sqlite3SchemaMutexHeld(db, 0, pDb->pSchema) );
+    sqlite3OpenTable(pParse, 0, p->iDb, pDb->pSchema->pSeqTab, OP_OpenRead);
+    sqlite3VdbeLoadString(v, memId-1, p->pTab->zName);
+    aOp = sqlite3VdbeAddOpList(v, ArraySize(autoInc), autoInc, iLn);
+    if( aOp==0 ) break;
+    aOp[0].p2 = memId;
+    aOp[0].p3 = memId+1;
+    aOp[2].p3 = memId;
+    aOp[3].p1 = memId-1;
+    aOp[3].p3 = memId;
+    aOp[3].p5 = SQLITE_JUMPIFNULL;
+    aOp[4].p2 = memId+1;
+    aOp[5].p3 = memId;
+    aOp[8].p2 = memId;
+  }
+}
+
+/*
+** Update the maximum rowid for an autoincrement calculation.
+**
+** This routine should be called when the regRowid register holds a
+** new rowid that is about to be inserted.  If that new rowid is
+** larger than the maximum rowid in the memId memory cell, then the
+** memory cell is updated.
+*/
+static void autoIncStep(Parse *pParse, int memId, int regRowid){
+  if( memId>0 ){
+    sqlite3VdbeAddOp2(pParse->pVdbe, OP_MemMax, memId, regRowid);
+  }
+}
+
+/*
+** This routine generates the code needed to write autoincrement
+** maximum rowid values back into the sqlite_sequence register.
+** Every statement that might do an INSERT into an autoincrement
+** table (either directly or through triggers) needs to call this
+** routine just before the "exit" code.
+*/
+static SQLITE_NOINLINE void autoIncrementEnd(Parse *pParse){
+  AutoincInfo *p;
+  Vdbe *v = pParse->pVdbe;
+  sqlite3 *db = pParse->db;
+
+  assert( v );
+  for(p = pParse->pAinc; p; p = p->pNext){
+    static const int iLn = VDBE_OFFSET_LINENO(2);
+    static const VdbeOpList autoIncEnd[] = {
+      /* 0 */ {OP_NotNull,     0, 2, 0},
+      /* 1 */ {OP_NewRowid,    0, 0, 0},
+      /* 2 */ {OP_MakeRecord,  0, 2, 0},
+      /* 3 */ {OP_Insert,      0, 0, 0},
+      /* 4 */ {OP_Close,       0, 0, 0}
+    };
+    VdbeOp *aOp;
+    Db *pDb = &db->aDb[p->iDb];
+    int iRec;
+    int memId = p->regCtr;
+
+    iRec = sqlite3GetTempReg(pParse);
+    assert( sqlite3SchemaMutexHeld(db, 0, pDb->pSchema) );
+    sqlite3OpenTable(pParse, 0, p->iDb, pDb->pSchema->pSeqTab, OP_OpenWrite);
+    aOp = sqlite3VdbeAddOpList(v, ArraySize(autoIncEnd), autoIncEnd, iLn);
+    if( aOp==0 ) break;
+    aOp[0].p1 = memId+1;
+    aOp[1].p2 = memId+1;
+    aOp[2].p1 = memId-1;
+    aOp[2].p3 = iRec;
+    aOp[3].p2 = iRec;
+    aOp[3].p3 = memId+1;
+    aOp[3].p5 = OPFLAG_APPEND;
+    sqlite3ReleaseTempReg(pParse, iRec);
+  }
+}
+SQLITE_PRIVATE void sqlite3AutoincrementEnd(Parse *pParse){
+  if( pParse->pAinc ) autoIncrementEnd(pParse);
+}
+#else
+/*
+** If SQLITE_OMIT_AUTOINCREMENT is defined, then the three routines
+** above are all no-ops
+*/
+# define autoIncBegin(A,B,C) (0)
+# define autoIncStep(A,B,C)
+#endif /* SQLITE_OMIT_AUTOINCREMENT */
+
+
+/* Forward declaration */
+static int xferOptimization(
+  Parse *pParse,        /* Parser context */
+  Table *pDest,         /* The table we are inserting into */
+  Select *pSelect,      /* A SELECT statement to use as the data source */
+  int onError,          /* How to handle constraint errors */
+  int iDbDest           /* The database of pDest */
+);
+
+/*
+** This routine is called to handle SQL of the following forms:
+**
+**    insert into TABLE (IDLIST) values(EXPRLIST),(EXPRLIST),...
+**    insert into TABLE (IDLIST) select
+**    insert into TABLE (IDLIST) default values
+**
+** The IDLIST following the table name is always optional.  If omitted,
+** then a list of all (non-hidden) columns for the table is substituted.
+** The IDLIST appears in the pColumn parameter.  pColumn is NULL if IDLIST
+** is omitted.
+**
+** For the pSelect parameter holds the values to be inserted for the
+** first two forms shown above.  A VALUES clause is really just short-hand
+** for a SELECT statement that omits the FROM clause and everything else
+** that follows.  If the pSelect parameter is NULL, that means that the
+** DEFAULT VALUES form of the INSERT statement is intended.
+**
+** The code generated follows one of four templates.  For a simple
+** insert with data coming from a single-row VALUES clause, the code executes
+** once straight down through.  Pseudo-code follows (we call this
+** the "1st template"):
+**
+**         open write cursor to <table> and its indices
+**         put VALUES clause expressions into registers
+**         write the resulting record into <table>
+**         cleanup
+**
+** The three remaining templates assume the statement is of the form
+**
+**   INSERT INTO <table> SELECT ...
+**
+** If the SELECT clause is of the restricted form "SELECT * FROM <table2>" -
+** in other words if the SELECT pulls all columns from a single table
+** and there is no WHERE or LIMIT or GROUP BY or ORDER BY clauses, and
+** if <table2> and <table1> are distinct tables but have identical
+** schemas, including all the same indices, then a special optimization
+** is invoked that copies raw records from <table2> over to <table1>.
+** See the xferOptimization() function for the implementation of this
+** template.  This is the 2nd template.
+**
+**         open a write cursor to <table>
+**         open read cursor on <table2>
+**         transfer all records in <table2> over to <table>
+**         close cursors
+**         foreach index on <table>
+**           open a write cursor on the <table> index
+**           open a read cursor on the corresponding <table2> index
+**           transfer all records from the read to the write cursors
+**           close cursors
+**         end foreach
+**
+** The 3rd template is for when the second template does not apply
+** and the SELECT clause does not read from <table> at any time.
+** The generated code follows this template:
+**
+**         X <- A
+**         goto B
+**      A: setup for the SELECT
+**         loop over the rows in the SELECT
+**           load values into registers R..R+n
+**           yield X
+**         end loop
+**         cleanup after the SELECT
+**         end-coroutine X
+**      B: open write cursor to <table> and its indices
+**      C: yield X, at EOF goto D
+**         insert the select result into <table> from R..R+n
+**         goto C
+**      D: cleanup
+**
+** The 4th template is used if the insert statement takes its
+** values from a SELECT but the data is being inserted into a table
+** that is also read as part of the SELECT.  In the third form,
+** we have to use an intermediate table to store the results of
+** the select.  The template is like this:
+**
+**         X <- A
+**         goto B
+**      A: setup for the SELECT
+**         loop over the tables in the SELECT
+**           load value into register R..R+n
+**           yield X
+**         end loop
+**         cleanup after the SELECT
+**         end co-routine R
+**      B: open temp table
+**      L: yield X, at EOF goto M
+**         insert row from R..R+n into temp table
+**         goto L
+**      M: open write cursor to <table> and its indices
+**         rewind temp table
+**      C: loop over rows of intermediate table
+**           transfer values form intermediate table into <table>
+**         end loop
+**      D: cleanup
+*/
+SQLITE_PRIVATE void sqlite3Insert(
+  Parse *pParse,        /* Parser context */
+  SrcList *pTabList,    /* Name of table into which we are inserting */
+  Select *pSelect,      /* A SELECT statement to use as the data source */
+  IdList *pColumn,      /* Column names corresponding to IDLIST. */
+  int onError           /* How to handle constraint errors */
+){
+  sqlite3 *db;          /* The main database structure */
+  Table *pTab;          /* The table to insert into.  aka TABLE */
+  char *zTab;           /* Name of the table into which we are inserting */
+  int i, j, idx;        /* Loop counters */
+  Vdbe *v;              /* Generate code into this virtual machine */
+  Index *pIdx;          /* For looping over indices of the table */
+  int nColumn;          /* Number of columns in the data */
+  int nHidden = 0;      /* Number of hidden columns if TABLE is virtual */
+  int iDataCur = 0;     /* VDBE cursor that is the main data repository */
+  int iIdxCur = 0;      /* First index cursor */
+  int ipkColumn = -1;   /* Column that is the INTEGER PRIMARY KEY */
+  int endOfLoop;        /* Label for the end of the insertion loop */
+  int srcTab = 0;       /* Data comes from this temporary cursor if >=0 */
+  int addrInsTop = 0;   /* Jump to label "D" */
+  int addrCont = 0;     /* Top of insert loop. Label "C" in templates 3 and 4 */
+  SelectDest dest;      /* Destination for SELECT on rhs of INSERT */
+  int iDb;              /* Index of database holding TABLE */
+  u8 useTempTable = 0;  /* Store SELECT results in intermediate table */
+  u8 appendFlag = 0;    /* True if the insert is likely to be an append */
+  u8 withoutRowid;      /* 0 for normal table.  1 for WITHOUT ROWID table */
+  u8 bIdListInOrder;    /* True if IDLIST is in table order */
+  ExprList *pList = 0;  /* List of VALUES() to be inserted  */
+
+  /* Register allocations */
+  int regFromSelect = 0;/* Base register for data coming from SELECT */
+  int regAutoinc = 0;   /* Register holding the AUTOINCREMENT counter */
+  int regRowCount = 0;  /* Memory cell used for the row counter */
+  int regIns;           /* Block of regs holding rowid+data being inserted */
+  int regRowid;         /* registers holding insert rowid */
+  int regData;          /* register holding first column to insert */
+  int *aRegIdx = 0;     /* One register allocated to each index */
+
+#ifndef SQLITE_OMIT_TRIGGER
+  int isView;                 /* True if attempting to insert into a view */
+  Trigger *pTrigger;          /* List of triggers on pTab, if required */
+  int tmask;                  /* Mask of trigger times */
+#endif
+
+  db = pParse->db;
+  memset(&dest, 0, sizeof(dest));
+  if( pParse->nErr || db->mallocFailed ){
+    goto insert_cleanup;
+  }
+
+  /* If the Select object is really just a simple VALUES() list with a
+  ** single row (the common case) then keep that one row of values
+  ** and discard the other (unused) parts of the pSelect object
+  */
+  if( pSelect && (pSelect->selFlags & SF_Values)!=0 && pSelect->pPrior==0 ){
+    pList = pSelect->pEList;
+    pSelect->pEList = 0;
+    sqlite3SelectDelete(db, pSelect);
+    pSelect = 0;
+  }
+
+  /* Locate the table into which we will be inserting new information.
+  */
+  assert( pTabList->nSrc==1 );
+  zTab = pTabList->a[0].zName;
+  if( NEVER(zTab==0) ) goto insert_cleanup;
+  pTab = sqlite3SrcListLookup(pParse, pTabList);
+  if( pTab==0 ){
+    goto insert_cleanup;
+  }
+  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+  assert( iDb<db->nDb );
+  if( sqlite3AuthCheck(pParse, SQLITE_INSERT, pTab->zName, 0,
+                       db->aDb[iDb].zDbSName) ){
+    goto insert_cleanup;
+  }
+  withoutRowid = !HasRowid(pTab);
+
+  /* Figure out if we have any triggers and if the table being
+  ** inserted into is a view
+  */
+#ifndef SQLITE_OMIT_TRIGGER
+  pTrigger = sqlite3TriggersExist(pParse, pTab, TK_INSERT, 0, &tmask);
+  isView = pTab->pSelect!=0;
+#else
+# define pTrigger 0
+# define tmask 0
+# define isView 0
+#endif
+#ifdef SQLITE_OMIT_VIEW
+# undef isView
+# define isView 0
+#endif
+  assert( (pTrigger && tmask) || (pTrigger==0 && tmask==0) );
+
+  /* If pTab is really a view, make sure it has been initialized.
+  ** ViewGetColumnNames() is a no-op if pTab is not a view.
+  */
+  if( sqlite3ViewGetColumnNames(pParse, pTab) ){
+    goto insert_cleanup;
+  }
+
+  /* Cannot insert into a read-only table.
+  */
+  if( sqlite3IsReadOnly(pParse, pTab, tmask) ){
+    goto insert_cleanup;
+  }
+
+  /* Allocate a VDBE
+  */
+  v = sqlite3GetVdbe(pParse);
+  if( v==0 ) goto insert_cleanup;
+  if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
+  sqlite3BeginWriteOperation(pParse, pSelect || pTrigger, iDb);
+
+#ifndef SQLITE_OMIT_XFER_OPT
+  /* If the statement is of the form
+  **
+  **       INSERT INTO <table1> SELECT * FROM <table2>;
+  **
+  ** Then special optimizations can be applied that make the transfer
+  ** very fast and which reduce fragmentation of indices.
+  **
+  ** This is the 2nd template.
+  */
+  if( pColumn==0 && xferOptimization(pParse, pTab, pSelect, onError, iDb) ){
+    assert( !pTrigger );
+    assert( pList==0 );
+    goto insert_end;
+  }
+#endif /* SQLITE_OMIT_XFER_OPT */
+
+  /* If this is an AUTOINCREMENT table, look up the sequence number in the
+  ** sqlite_sequence table and store it in memory cell regAutoinc.
+  */
+  regAutoinc = autoIncBegin(pParse, iDb, pTab);
+
+  /* Allocate registers for holding the rowid of the new row,
+  ** the content of the new row, and the assembled row record.
+  */
+  regRowid = regIns = pParse->nMem+1;
+  pParse->nMem += pTab->nCol + 1;
+  if( IsVirtual(pTab) ){
+    regRowid++;
+    pParse->nMem++;
+  }
+  regData = regRowid+1;
+
+  /* If the INSERT statement included an IDLIST term, then make sure
+  ** all elements of the IDLIST really are columns of the table and 
+  ** remember the column indices.
+  **
+  ** If the table has an INTEGER PRIMARY KEY column and that column
+  ** is named in the IDLIST, then record in the ipkColumn variable
+  ** the index into IDLIST of the primary key column.  ipkColumn is
+  ** the index of the primary key as it appears in IDLIST, not as
+  ** is appears in the original table.  (The index of the INTEGER
+  ** PRIMARY KEY in the original table is pTab->iPKey.)
+  */
+  bIdListInOrder = (pTab->tabFlags & TF_OOOHidden)==0;
+  if( pColumn ){
+    for(i=0; i<pColumn->nId; i++){
+      pColumn->a[i].idx = -1;
+    }
+    for(i=0; i<pColumn->nId; i++){
+      for(j=0; j<pTab->nCol; j++){
+        if( sqlite3StrICmp(pColumn->a[i].zName, pTab->aCol[j].zName)==0 ){
+          pColumn->a[i].idx = j;
+          if( i!=j ) bIdListInOrder = 0;
+          if( j==pTab->iPKey ){
+            ipkColumn = i;  assert( !withoutRowid );
+          }
+          break;
+        }
+      }
+      if( j>=pTab->nCol ){
+        if( sqlite3IsRowid(pColumn->a[i].zName) && !withoutRowid ){
+          ipkColumn = i;
+          bIdListInOrder = 0;
+        }else{
+          sqlite3ErrorMsg(pParse, "table %S has no column named %s",
+              pTabList, 0, pColumn->a[i].zName);
+          pParse->checkSchema = 1;
+          goto insert_cleanup;
+        }
+      }
+    }
+  }
+
+  /* Figure out how many columns of data are supplied.  If the data
+  ** is coming from a SELECT statement, then generate a co-routine that
+  ** produces a single row of the SELECT on each invocation.  The
+  ** co-routine is the common header to the 3rd and 4th templates.
+  */
+  if( pSelect ){
+    /* Data is coming from a SELECT or from a multi-row VALUES clause.
+    ** Generate a co-routine to run the SELECT. */
+    int regYield;       /* Register holding co-routine entry-point */
+    int addrTop;        /* Top of the co-routine */
+    int rc;             /* Result code */
+
+    regYield = ++pParse->nMem;
+    addrTop = sqlite3VdbeCurrentAddr(v) + 1;
+    sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, addrTop);
+    sqlite3SelectDestInit(&dest, SRT_Coroutine, regYield);
+    dest.iSdst = bIdListInOrder ? regData : 0;
+    dest.nSdst = pTab->nCol;
+    rc = sqlite3Select(pParse, pSelect, &dest);
+    regFromSelect = dest.iSdst;
+    if( rc || db->mallocFailed || pParse->nErr ) goto insert_cleanup;
+    sqlite3VdbeEndCoroutine(v, regYield);
+    sqlite3VdbeJumpHere(v, addrTop - 1);                       /* label B: */
+    assert( pSelect->pEList );
+    nColumn = pSelect->pEList->nExpr;
+
+    /* Set useTempTable to TRUE if the result of the SELECT statement
+    ** should be written into a temporary table (template 4).  Set to
+    ** FALSE if each output row of the SELECT can be written directly into
+    ** the destination table (template 3).
+    **
+    ** A temp table must be used if the table being updated is also one
+    ** of the tables being read by the SELECT statement.  Also use a 
+    ** temp table in the case of row triggers.
+    */
+    if( pTrigger || readsTable(pParse, iDb, pTab) ){
+      useTempTable = 1;
+    }
+
+    if( useTempTable ){
+      /* Invoke the coroutine to extract information from the SELECT
+      ** and add it to a transient table srcTab.  The code generated
+      ** here is from the 4th template:
+      **
+      **      B: open temp table
+      **      L: yield X, goto M at EOF
+      **         insert row from R..R+n into temp table
+      **         goto L
+      **      M: ...
+      */
+      int regRec;          /* Register to hold packed record */
+      int regTempRowid;    /* Register to hold temp table ROWID */
+      int addrL;           /* Label "L" */
+
+      srcTab = pParse->nTab++;
+      regRec = sqlite3GetTempReg(pParse);
+      regTempRowid = sqlite3GetTempReg(pParse);
+      sqlite3VdbeAddOp2(v, OP_OpenEphemeral, srcTab, nColumn);
+      addrL = sqlite3VdbeAddOp1(v, OP_Yield, dest.iSDParm); VdbeCoverage(v);
+      sqlite3VdbeAddOp3(v, OP_MakeRecord, regFromSelect, nColumn, regRec);
+      sqlite3VdbeAddOp2(v, OP_NewRowid, srcTab, regTempRowid);
+      sqlite3VdbeAddOp3(v, OP_Insert, srcTab, regRec, regTempRowid);
+      sqlite3VdbeGoto(v, addrL);
+      sqlite3VdbeJumpHere(v, addrL);
+      sqlite3ReleaseTempReg(pParse, regRec);
+      sqlite3ReleaseTempReg(pParse, regTempRowid);
+    }
+  }else{
+    /* This is the case if the data for the INSERT is coming from a 
+    ** single-row VALUES clause
+    */
+    NameContext sNC;
+    memset(&sNC, 0, sizeof(sNC));
+    sNC.pParse = pParse;
+    srcTab = -1;
+    assert( useTempTable==0 );
+    if( pList ){
+      nColumn = pList->nExpr;
+      if( sqlite3ResolveExprListNames(&sNC, pList) ){
+        goto insert_cleanup;
+      }
+    }else{
+      nColumn = 0;
+    }
+  }
+
+  /* If there is no IDLIST term but the table has an integer primary
+  ** key, the set the ipkColumn variable to the integer primary key 
+  ** column index in the original table definition.
+  */
+  if( pColumn==0 && nColumn>0 ){
+    ipkColumn = pTab->iPKey;
+  }
+
+  /* Make sure the number of columns in the source data matches the number
+  ** of columns to be inserted into the table.
+  */
+  for(i=0; i<pTab->nCol; i++){
+    nHidden += (IsHiddenColumn(&pTab->aCol[i]) ? 1 : 0);
+  }
+  if( pColumn==0 && nColumn && nColumn!=(pTab->nCol-nHidden) ){
+    sqlite3ErrorMsg(pParse, 
+       "table %S has %d columns but %d values were supplied",
+       pTabList, 0, pTab->nCol-nHidden, nColumn);
+    goto insert_cleanup;
+  }
+  if( pColumn!=0 && nColumn!=pColumn->nId ){
+    sqlite3ErrorMsg(pParse, "%d values for %d columns", nColumn, pColumn->nId);
+    goto insert_cleanup;
+  }
+    
+  /* Initialize the count of rows to be inserted
+  */
+  if( db->flags & SQLITE_CountRows ){
+    regRowCount = ++pParse->nMem;
+    sqlite3VdbeAddOp2(v, OP_Integer, 0, regRowCount);
+  }
+
+  /* If this is not a view, open the table and and all indices */
+  if( !isView ){
+    int nIdx;
+    nIdx = sqlite3OpenTableAndIndices(pParse, pTab, OP_OpenWrite, 0, -1, 0,
+                                      &iDataCur, &iIdxCur);
+    aRegIdx = sqlite3DbMallocRawNN(db, sizeof(int)*(nIdx+1));
+    if( aRegIdx==0 ){
+      goto insert_cleanup;
+    }
+    for(i=0; i<nIdx; i++){
+      aRegIdx[i] = ++pParse->nMem;
+    }
+  }
+
+  /* This is the top of the main insertion loop */
+  if( useTempTable ){
+    /* This block codes the top of loop only.  The complete loop is the
+    ** following pseudocode (template 4):
+    **
+    **         rewind temp table, if empty goto D
+    **      C: loop over rows of intermediate table
+    **           transfer values form intermediate table into <table>
+    **         end loop
+    **      D: ...
+    */
+    addrInsTop = sqlite3VdbeAddOp1(v, OP_Rewind, srcTab); VdbeCoverage(v);
+    addrCont = sqlite3VdbeCurrentAddr(v);
+  }else if( pSelect ){
+    /* This block codes the top of loop only.  The complete loop is the
+    ** following pseudocode (template 3):
+    **
+    **      C: yield X, at EOF goto D
+    **         insert the select result into <table> from R..R+n
+    **         goto C
+    **      D: ...
+    */
+    addrInsTop = addrCont = sqlite3VdbeAddOp1(v, OP_Yield, dest.iSDParm);
+    VdbeCoverage(v);
+  }
+
+  /* Run the BEFORE and INSTEAD OF triggers, if there are any
+  */
+  endOfLoop = sqlite3VdbeMakeLabel(v);
+  if( tmask & TRIGGER_BEFORE ){
+    int regCols = sqlite3GetTempRange(pParse, pTab->nCol+1);
+
+    /* build the NEW.* reference row.  Note that if there is an INTEGER
+    ** PRIMARY KEY into which a NULL is being inserted, that NULL will be
+    ** translated into a unique ID for the row.  But on a BEFORE trigger,
+    ** we do not know what the unique ID will be (because the insert has
+    ** not happened yet) so we substitute a rowid of -1
+    */
+    if( ipkColumn<0 ){
+      sqlite3VdbeAddOp2(v, OP_Integer, -1, regCols);
+    }else{
+      int addr1;
+      assert( !withoutRowid );
+      if( useTempTable ){
+        sqlite3VdbeAddOp3(v, OP_Column, srcTab, ipkColumn, regCols);
+      }else{
+        assert( pSelect==0 );  /* Otherwise useTempTable is true */
+        sqlite3ExprCode(pParse, pList->a[ipkColumn].pExpr, regCols);
+      }
+      addr1 = sqlite3VdbeAddOp1(v, OP_NotNull, regCols); VdbeCoverage(v);
+      sqlite3VdbeAddOp2(v, OP_Integer, -1, regCols);
+      sqlite3VdbeJumpHere(v, addr1);
+      sqlite3VdbeAddOp1(v, OP_MustBeInt, regCols); VdbeCoverage(v);
+    }
+
+    /* Cannot have triggers on a virtual table. If it were possible,
+    ** this block would have to account for hidden column.
+    */
+    assert( !IsVirtual(pTab) );
+
+    /* Create the new column data
+    */
+    for(i=j=0; i<pTab->nCol; i++){
+      if( pColumn ){
+        for(j=0; j<pColumn->nId; j++){
+          if( pColumn->a[j].idx==i ) break;
+        }
+      }
+      if( (!useTempTable && !pList) || (pColumn && j>=pColumn->nId)
+            || (pColumn==0 && IsOrdinaryHiddenColumn(&pTab->aCol[i])) ){
+        sqlite3ExprCode(pParse, pTab->aCol[i].pDflt, regCols+i+1);
+      }else if( useTempTable ){
+        sqlite3VdbeAddOp3(v, OP_Column, srcTab, j, regCols+i+1); 
+      }else{
+        assert( pSelect==0 ); /* Otherwise useTempTable is true */
+        sqlite3ExprCodeAndCache(pParse, pList->a[j].pExpr, regCols+i+1);
+      }
+      if( pColumn==0 && !IsOrdinaryHiddenColumn(&pTab->aCol[i]) ) j++;
+    }
+
+    /* If this is an INSERT on a view with an INSTEAD OF INSERT trigger,
+    ** do not attempt any conversions before assembling the record.
+    ** If this is a real table, attempt conversions as required by the
+    ** table column affinities.
+    */
+    if( !isView ){
+      sqlite3TableAffinity(v, pTab, regCols+1);
+    }
+
+    /* Fire BEFORE or INSTEAD OF triggers */
+    sqlite3CodeRowTrigger(pParse, pTrigger, TK_INSERT, 0, TRIGGER_BEFORE, 
+        pTab, regCols-pTab->nCol-1, onError, endOfLoop);
+
+    sqlite3ReleaseTempRange(pParse, regCols, pTab->nCol+1);
+  }
+
+  /* Compute the content of the next row to insert into a range of
+  ** registers beginning at regIns.
+  */
+  if( !isView ){
+    if( IsVirtual(pTab) ){
+      /* The row that the VUpdate opcode will delete: none */
+      sqlite3VdbeAddOp2(v, OP_Null, 0, regIns);
+    }
+    if( ipkColumn>=0 ){
+      if( useTempTable ){
+        sqlite3VdbeAddOp3(v, OP_Column, srcTab, ipkColumn, regRowid);
+      }else if( pSelect ){
+        sqlite3VdbeAddOp2(v, OP_Copy, regFromSelect+ipkColumn, regRowid);
+      }else{
+        VdbeOp *pOp;
+        sqlite3ExprCode(pParse, pList->a[ipkColumn].pExpr, regRowid);
+        pOp = sqlite3VdbeGetOp(v, -1);
+        if( ALWAYS(pOp) && pOp->opcode==OP_Null && !IsVirtual(pTab) ){
+          appendFlag = 1;
+          pOp->opcode = OP_NewRowid;
+          pOp->p1 = iDataCur;
+          pOp->p2 = regRowid;
+          pOp->p3 = regAutoinc;
+        }
+      }
+      /* If the PRIMARY KEY expression is NULL, then use OP_NewRowid
+      ** to generate a unique primary key value.
+      */
+      if( !appendFlag ){
+        int addr1;
+        if( !IsVirtual(pTab) ){
+          addr1 = sqlite3VdbeAddOp1(v, OP_NotNull, regRowid); VdbeCoverage(v);
+          sqlite3VdbeAddOp3(v, OP_NewRowid, iDataCur, regRowid, regAutoinc);
+          sqlite3VdbeJumpHere(v, addr1);
+        }else{
+          addr1 = sqlite3VdbeCurrentAddr(v);
+          sqlite3VdbeAddOp2(v, OP_IsNull, regRowid, addr1+2); VdbeCoverage(v);
+        }
+        sqlite3VdbeAddOp1(v, OP_MustBeInt, regRowid); VdbeCoverage(v);
+      }
+    }else if( IsVirtual(pTab) || withoutRowid ){
+      sqlite3VdbeAddOp2(v, OP_Null, 0, regRowid);
+    }else{
+      sqlite3VdbeAddOp3(v, OP_NewRowid, iDataCur, regRowid, regAutoinc);
+      appendFlag = 1;
+    }
+    autoIncStep(pParse, regAutoinc, regRowid);
+
+    /* Compute data for all columns of the new entry, beginning
+    ** with the first column.
+    */
+    nHidden = 0;
+    for(i=0; i<pTab->nCol; i++){
+      int iRegStore = regRowid+1+i;
+      if( i==pTab->iPKey ){
+        /* The value of the INTEGER PRIMARY KEY column is always a NULL.
+        ** Whenever this column is read, the rowid will be substituted
+        ** in its place.  Hence, fill this column with a NULL to avoid
+        ** taking up data space with information that will never be used.
+        ** As there may be shallow copies of this value, make it a soft-NULL */
+        sqlite3VdbeAddOp1(v, OP_SoftNull, iRegStore);
+        continue;
+      }
+      if( pColumn==0 ){
+        if( IsHiddenColumn(&pTab->aCol[i]) ){
+          j = -1;
+          nHidden++;
+        }else{
+          j = i - nHidden;
+        }
+      }else{
+        for(j=0; j<pColumn->nId; j++){
+          if( pColumn->a[j].idx==i ) break;
+        }
+      }
+      if( j<0 || nColumn==0 || (pColumn && j>=pColumn->nId) ){
+        sqlite3ExprCodeFactorable(pParse, pTab->aCol[i].pDflt, iRegStore);
+      }else if( useTempTable ){
+        sqlite3VdbeAddOp3(v, OP_Column, srcTab, j, iRegStore); 
+      }else if( pSelect ){
+        if( regFromSelect!=regData ){
+          sqlite3VdbeAddOp2(v, OP_SCopy, regFromSelect+j, iRegStore);
+        }
+      }else{
+        sqlite3ExprCode(pParse, pList->a[j].pExpr, iRegStore);
+      }
+    }
+
+    /* Generate code to check constraints and generate index keys and
+    ** do the insertion.
+    */
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    if( IsVirtual(pTab) ){
+      const char *pVTab = (const char *)sqlite3GetVTable(db, pTab);
+      sqlite3VtabMakeWritable(pParse, pTab);
+      sqlite3VdbeAddOp4(v, OP_VUpdate, 1, pTab->nCol+2, regIns, pVTab, P4_VTAB);
+      sqlite3VdbeChangeP5(v, onError==OE_Default ? OE_Abort : onError);
+      sqlite3MayAbort(pParse);
+    }else
+#endif
+    {
+      int isReplace;    /* Set to true if constraints may cause a replace */
+      sqlite3GenerateConstraintChecks(pParse, pTab, aRegIdx, iDataCur, iIdxCur,
+          regIns, 0, ipkColumn>=0, onError, endOfLoop, &isReplace, 0
+      );
+      sqlite3FkCheck(pParse, pTab, 0, regIns, 0, 0);
+      sqlite3CompleteInsertion(pParse, pTab, iDataCur, iIdxCur,
+                               regIns, aRegIdx, 0, appendFlag, isReplace==0);
+    }
+  }
+
+  /* Update the count of rows that are inserted
+  */
+  if( (db->flags & SQLITE_CountRows)!=0 ){
+    sqlite3VdbeAddOp2(v, OP_AddImm, regRowCount, 1);
+  }
+
+  if( pTrigger ){
+    /* Code AFTER triggers */
+    sqlite3CodeRowTrigger(pParse, pTrigger, TK_INSERT, 0, TRIGGER_AFTER, 
+        pTab, regData-2-pTab->nCol, onError, endOfLoop);
+  }
+
+  /* The bottom of the main insertion loop, if the data source
+  ** is a SELECT statement.
+  */
+  sqlite3VdbeResolveLabel(v, endOfLoop);
+  if( useTempTable ){
+    sqlite3VdbeAddOp2(v, OP_Next, srcTab, addrCont); VdbeCoverage(v);
+    sqlite3VdbeJumpHere(v, addrInsTop);
+    sqlite3VdbeAddOp1(v, OP_Close, srcTab);
+  }else if( pSelect ){
+    sqlite3VdbeGoto(v, addrCont);
+    sqlite3VdbeJumpHere(v, addrInsTop);
+  }
+
+  if( !IsVirtual(pTab) && !isView ){
+    /* Close all tables opened */
+    if( iDataCur<iIdxCur ) sqlite3VdbeAddOp1(v, OP_Close, iDataCur);
+    for(idx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, idx++){
+      sqlite3VdbeAddOp1(v, OP_Close, idx+iIdxCur);
+    }
+  }
+
+insert_end:
+  /* Update the sqlite_sequence table by storing the content of the
+  ** maximum rowid counter values recorded while inserting into
+  ** autoincrement tables.
+  */
+  if( pParse->nested==0 && pParse->pTriggerTab==0 ){
+    sqlite3AutoincrementEnd(pParse);
+  }
+
+  /*
+  ** Return the number of rows inserted. If this routine is 
+  ** generating code because of a call to sqlite3NestedParse(), do not
+  ** invoke the callback function.
+  */
+  if( (db->flags&SQLITE_CountRows) && !pParse->nested && !pParse->pTriggerTab ){
+    sqlite3VdbeAddOp2(v, OP_ResultRow, regRowCount, 1);
+    sqlite3VdbeSetNumCols(v, 1);
+    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows inserted", SQLITE_STATIC);
+  }
+
+insert_cleanup:
+  sqlite3SrcListDelete(db, pTabList);
+  sqlite3ExprListDelete(db, pList);
+  sqlite3SelectDelete(db, pSelect);
+  sqlite3IdListDelete(db, pColumn);
+  sqlite3DbFree(db, aRegIdx);
+}
+
+/* Make sure "isView" and other macros defined above are undefined. Otherwise
+** they may interfere with compilation of other functions in this file
+** (or in another file, if this file becomes part of the amalgamation).  */
+#ifdef isView
+ #undef isView
+#endif
+#ifdef pTrigger
+ #undef pTrigger
+#endif
+#ifdef tmask
+ #undef tmask
+#endif
+
+/*
+** Meanings of bits in of pWalker->eCode for checkConstraintUnchanged()
+*/
+#define CKCNSTRNT_COLUMN   0x01    /* CHECK constraint uses a changing column */
+#define CKCNSTRNT_ROWID    0x02    /* CHECK constraint references the ROWID */
+
+/* This is the Walker callback from checkConstraintUnchanged().  Set
+** bit 0x01 of pWalker->eCode if
+** pWalker->eCode to 0 if this expression node references any of the
+** columns that are being modifed by an UPDATE statement.
+*/
+static int checkConstraintExprNode(Walker *pWalker, Expr *pExpr){
+  if( pExpr->op==TK_COLUMN ){
+    assert( pExpr->iColumn>=0 || pExpr->iColumn==-1 );
+    if( pExpr->iColumn>=0 ){
+      if( pWalker->u.aiCol[pExpr->iColumn]>=0 ){
+        pWalker->eCode |= CKCNSTRNT_COLUMN;
+      }
+    }else{
+      pWalker->eCode |= CKCNSTRNT_ROWID;
+    }
+  }
+  return WRC_Continue;
+}
+
+/*
+** pExpr is a CHECK constraint on a row that is being UPDATE-ed.  The
+** only columns that are modified by the UPDATE are those for which
+** aiChng[i]>=0, and also the ROWID is modified if chngRowid is true.
+**
+** Return true if CHECK constraint pExpr does not use any of the
+** changing columns (or the rowid if it is changing).  In other words,
+** return true if this CHECK constraint can be skipped when validating
+** the new row in the UPDATE statement.
+*/
+static int checkConstraintUnchanged(Expr *pExpr, int *aiChng, int chngRowid){
+  Walker w;
+  memset(&w, 0, sizeof(w));
+  w.eCode = 0;
+  w.xExprCallback = checkConstraintExprNode;
+  w.u.aiCol = aiChng;
+  sqlite3WalkExpr(&w, pExpr);
+  if( !chngRowid ){
+    testcase( (w.eCode & CKCNSTRNT_ROWID)!=0 );
+    w.eCode &= ~CKCNSTRNT_ROWID;
+  }
+  testcase( w.eCode==0 );
+  testcase( w.eCode==CKCNSTRNT_COLUMN );
+  testcase( w.eCode==CKCNSTRNT_ROWID );
+  testcase( w.eCode==(CKCNSTRNT_ROWID|CKCNSTRNT_COLUMN) );
+  return !w.eCode;
+}
+
+/*
+** Generate code to do constraint checks prior to an INSERT or an UPDATE
+** on table pTab.
+**
+** The regNewData parameter is the first register in a range that contains
+** the data to be inserted or the data after the update.  There will be
+** pTab->nCol+1 registers in this range.  The first register (the one
+** that regNewData points to) will contain the new rowid, or NULL in the
+** case of a WITHOUT ROWID table.  The second register in the range will
+** contain the content of the first table column.  The third register will
+** contain the content of the second table column.  And so forth.
+**
+** The regOldData parameter is similar to regNewData except that it contains
+** the data prior to an UPDATE rather than afterwards.  regOldData is zero
+** for an INSERT.  This routine can distinguish between UPDATE and INSERT by
+** checking regOldData for zero.
+**
+** For an UPDATE, the pkChng boolean is true if the true primary key (the
+** rowid for a normal table or the PRIMARY KEY for a WITHOUT ROWID table)
+** might be modified by the UPDATE.  If pkChng is false, then the key of
+** the iDataCur content table is guaranteed to be unchanged by the UPDATE.
+**
+** For an INSERT, the pkChng boolean indicates whether or not the rowid
+** was explicitly specified as part of the INSERT statement.  If pkChng
+** is zero, it means that the either rowid is computed automatically or
+** that the table is a WITHOUT ROWID table and has no rowid.  On an INSERT,
+** pkChng will only be true if the INSERT statement provides an integer
+** value for either the rowid column or its INTEGER PRIMARY KEY alias.
+**
+** The code generated by this routine will store new index entries into
+** registers identified by aRegIdx[].  No index entry is created for
+** indices where aRegIdx[i]==0.  The order of indices in aRegIdx[] is
+** the same as the order of indices on the linked list of indices
+** at pTab->pIndex.
+**
+** The caller must have already opened writeable cursors on the main
+** table and all applicable indices (that is to say, all indices for which
+** aRegIdx[] is not zero).  iDataCur is the cursor for the main table when
+** inserting or updating a rowid table, or the cursor for the PRIMARY KEY
+** index when operating on a WITHOUT ROWID table.  iIdxCur is the cursor
+** for the first index in the pTab->pIndex list.  Cursors for other indices
+** are at iIdxCur+N for the N-th element of the pTab->pIndex list.
+**
+** This routine also generates code to check constraints.  NOT NULL,
+** CHECK, and UNIQUE constraints are all checked.  If a constraint fails,
+** then the appropriate action is performed.  There are five possible
+** actions: ROLLBACK, ABORT, FAIL, REPLACE, and IGNORE.
+**
+**  Constraint type  Action       What Happens
+**  ---------------  ----------   ----------------------------------------
+**  any              ROLLBACK     The current transaction is rolled back and
+**                                sqlite3_step() returns immediately with a
+**                                return code of SQLITE_CONSTRAINT.
+**
+**  any              ABORT        Back out changes from the current command
+**                                only (do not do a complete rollback) then
+**                                cause sqlite3_step() to return immediately
+**                                with SQLITE_CONSTRAINT.
+**
+**  any              FAIL         Sqlite3_step() returns immediately with a
+**                                return code of SQLITE_CONSTRAINT.  The
+**                                transaction is not rolled back and any
+**                                changes to prior rows are retained.
+**
+**  any              IGNORE       The attempt in insert or update the current
+**                                row is skipped, without throwing an error.
+**                                Processing continues with the next row.
+**                                (There is an immediate jump to ignoreDest.)
+**
+**  NOT NULL         REPLACE      The NULL value is replace by the default
+**                                value for that column.  If the default value
+**                                is NULL, the action is the same as ABORT.
+**
+**  UNIQUE           REPLACE      The other row that conflicts with the row
+**                                being inserted is removed.
+**
+**  CHECK            REPLACE      Illegal.  The results in an exception.
+**
+** Which action to take is determined by the overrideError parameter.
+** Or if overrideError==OE_Default, then the pParse->onError parameter
+** is used.  Or if pParse->onError==OE_Default then the onError value
+** for the constraint is used.
+*/
+SQLITE_PRIVATE void sqlite3GenerateConstraintChecks(
+  Parse *pParse,       /* The parser context */
+  Table *pTab,         /* The table being inserted or updated */
+  int *aRegIdx,        /* Use register aRegIdx[i] for index i.  0 for unused */
+  int iDataCur,        /* Canonical data cursor (main table or PK index) */
+  int iIdxCur,         /* First index cursor */
+  int regNewData,      /* First register in a range holding values to insert */
+  int regOldData,      /* Previous content.  0 for INSERTs */
+  u8 pkChng,           /* Non-zero if the rowid or PRIMARY KEY changed */
+  u8 overrideError,    /* Override onError to this if not OE_Default */
+  int ignoreDest,      /* Jump to this label on an OE_Ignore resolution */
+  int *pbMayReplace,   /* OUT: Set to true if constraint may cause a replace */
+  int *aiChng          /* column i is unchanged if aiChng[i]<0 */
+){
+  Vdbe *v;             /* VDBE under constrution */
+  Index *pIdx;         /* Pointer to one of the indices */
+  Index *pPk = 0;      /* The PRIMARY KEY index */
+  sqlite3 *db;         /* Database connection */
+  int i;               /* loop counter */
+  int ix;              /* Index loop counter */
+  int nCol;            /* Number of columns */
+  int onError;         /* Conflict resolution strategy */
+  int addr1;           /* Address of jump instruction */
+  int seenReplace = 0; /* True if REPLACE is used to resolve INT PK conflict */
+  int nPkField;        /* Number of fields in PRIMARY KEY. 1 for ROWID tables */
+  int ipkTop = 0;      /* Top of the rowid change constraint check */
+  int ipkBottom = 0;   /* Bottom of the rowid change constraint check */
+  u8 isUpdate;         /* True if this is an UPDATE operation */
+  u8 bAffinityDone = 0;  /* True if the OP_Affinity operation has been run */
+  int regRowid = -1;   /* Register holding ROWID value */
+
+  isUpdate = regOldData!=0;
+  db = pParse->db;
+  v = sqlite3GetVdbe(pParse);
+  assert( v!=0 );
+  assert( pTab->pSelect==0 );  /* This table is not a VIEW */
+  nCol = pTab->nCol;
+  
+  /* pPk is the PRIMARY KEY index for WITHOUT ROWID tables and NULL for
+  ** normal rowid tables.  nPkField is the number of key fields in the 
+  ** pPk index or 1 for a rowid table.  In other words, nPkField is the
+  ** number of fields in the true primary key of the table. */
+  if( HasRowid(pTab) ){
+    pPk = 0;
+    nPkField = 1;
+  }else{
+    pPk = sqlite3PrimaryKeyIndex(pTab);
+    nPkField = pPk->nKeyCol;
+  }
+
+  /* Record that this module has started */
+  VdbeModuleComment((v, "BEGIN: GenCnstCks(%d,%d,%d,%d,%d)",
+                     iDataCur, iIdxCur, regNewData, regOldData, pkChng));
+
+  /* Test all NOT NULL constraints.
+  */
+  for(i=0; i<nCol; i++){
+    if( i==pTab->iPKey ){
+      continue;        /* ROWID is never NULL */
+    }
+    if( aiChng && aiChng[i]<0 ){
+      /* Don't bother checking for NOT NULL on columns that do not change */
+      continue;
+    }
+    onError = pTab->aCol[i].notNull;
+    if( onError==OE_None ) continue;  /* This column is allowed to be NULL */
+    if( overrideError!=OE_Default ){
+      onError = overrideError;
+    }else if( onError==OE_Default ){
+      onError = OE_Abort;
+    }
+    if( onError==OE_Replace && pTab->aCol[i].pDflt==0 ){
+      onError = OE_Abort;
+    }
+    assert( onError==OE_Rollback || onError==OE_Abort || onError==OE_Fail
+        || onError==OE_Ignore || onError==OE_Replace );
+    switch( onError ){
+      case OE_Abort:
+        sqlite3MayAbort(pParse);
+        /* Fall through */
+      case OE_Rollback:
+      case OE_Fail: {
+        char *zMsg = sqlite3MPrintf(db, "%s.%s", pTab->zName,
+                                    pTab->aCol[i].zName);
+        sqlite3VdbeAddOp4(v, OP_HaltIfNull, SQLITE_CONSTRAINT_NOTNULL, onError,
+                          regNewData+1+i, zMsg, P4_DYNAMIC);
+        sqlite3VdbeChangeP5(v, P5_ConstraintNotNull);
+        VdbeCoverage(v);
+        break;
+      }
+      case OE_Ignore: {
+        sqlite3VdbeAddOp2(v, OP_IsNull, regNewData+1+i, ignoreDest);
+        VdbeCoverage(v);
+        break;
+      }
+      default: {
+        assert( onError==OE_Replace );
+        addr1 = sqlite3VdbeAddOp1(v, OP_NotNull, regNewData+1+i);
+           VdbeCoverage(v);
+        sqlite3ExprCode(pParse, pTab->aCol[i].pDflt, regNewData+1+i);
+        sqlite3VdbeJumpHere(v, addr1);
+        break;
+      }
+    }
+  }
+
+  /* Test all CHECK constraints
+  */
+#ifndef SQLITE_OMIT_CHECK
+  if( pTab->pCheck && (db->flags & SQLITE_IgnoreChecks)==0 ){
+    ExprList *pCheck = pTab->pCheck;
+    pParse->ckBase = regNewData+1;
+    onError = overrideError!=OE_Default ? overrideError : OE_Abort;
+    for(i=0; i<pCheck->nExpr; i++){
+      int allOk;
+      Expr *pExpr = pCheck->a[i].pExpr;
+      if( aiChng && checkConstraintUnchanged(pExpr, aiChng, pkChng) ) continue;
+      allOk = sqlite3VdbeMakeLabel(v);
+      sqlite3ExprIfTrue(pParse, pExpr, allOk, SQLITE_JUMPIFNULL);
+      if( onError==OE_Ignore ){
+        sqlite3VdbeGoto(v, ignoreDest);
+      }else{
+        char *zName = pCheck->a[i].zName;
+        if( zName==0 ) zName = pTab->zName;
+        if( onError==OE_Replace ) onError = OE_Abort; /* IMP: R-15569-63625 */
+        sqlite3HaltConstraint(pParse, SQLITE_CONSTRAINT_CHECK,
+                              onError, zName, P4_TRANSIENT,
+                              P5_ConstraintCheck);
+      }
+      sqlite3VdbeResolveLabel(v, allOk);
+    }
+  }
+#endif /* !defined(SQLITE_OMIT_CHECK) */
+
+  /* If rowid is changing, make sure the new rowid does not previously
+  ** exist in the table.
+  */
+  if( pkChng && pPk==0 ){
+    int addrRowidOk = sqlite3VdbeMakeLabel(v);
+
+    /* Figure out what action to take in case of a rowid collision */
+    onError = pTab->keyConf;
+    if( overrideError!=OE_Default ){
+      onError = overrideError;
+    }else if( onError==OE_Default ){
+      onError = OE_Abort;
+    }
+
+    if( isUpdate ){
+      /* pkChng!=0 does not mean that the rowid has change, only that
+      ** it might have changed.  Skip the conflict logic below if the rowid
+      ** is unchanged. */
+      sqlite3VdbeAddOp3(v, OP_Eq, regNewData, addrRowidOk, regOldData);
+      sqlite3VdbeChangeP5(v, SQLITE_NOTNULL);
+      VdbeCoverage(v);
+    }
+
+    /* If the response to a rowid conflict is REPLACE but the response
+    ** to some other UNIQUE constraint is FAIL or IGNORE, then we need
+    ** to defer the running of the rowid conflict checking until after
+    ** the UNIQUE constraints have run.
+    */
+    if( onError==OE_Replace && overrideError!=OE_Replace ){
+      for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+        if( pIdx->onError==OE_Ignore || pIdx->onError==OE_Fail ){
+          ipkTop = sqlite3VdbeAddOp0(v, OP_Goto);
+          break;
+        }
+      }
+    }
+
+    /* Check to see if the new rowid already exists in the table.  Skip
+    ** the following conflict logic if it does not. */
+    sqlite3VdbeAddOp3(v, OP_NotExists, iDataCur, addrRowidOk, regNewData);
+    VdbeCoverage(v);
+
+    /* Generate code that deals with a rowid collision */
+    switch( onError ){
+      default: {
+        onError = OE_Abort;
+        /* Fall thru into the next case */
+      }
+      case OE_Rollback:
+      case OE_Abort:
+      case OE_Fail: {
+        sqlite3RowidConstraint(pParse, onError, pTab);
+        break;
+      }
+      case OE_Replace: {
+        /* If there are DELETE triggers on this table and the
+        ** recursive-triggers flag is set, call GenerateRowDelete() to
+        ** remove the conflicting row from the table. This will fire
+        ** the triggers and remove both the table and index b-tree entries.
+        **
+        ** Otherwise, if there are no triggers or the recursive-triggers
+        ** flag is not set, but the table has one or more indexes, call 
+        ** GenerateRowIndexDelete(). This removes the index b-tree entries 
+        ** only. The table b-tree entry will be replaced by the new entry 
+        ** when it is inserted.  
+        **
+        ** If either GenerateRowDelete() or GenerateRowIndexDelete() is called,
+        ** also invoke MultiWrite() to indicate that this VDBE may require
+        ** statement rollback (if the statement is aborted after the delete
+        ** takes place). Earlier versions called sqlite3MultiWrite() regardless,
+        ** but being more selective here allows statements like:
+        **
+        **   REPLACE INTO t(rowid) VALUES($newrowid)
+        **
+        ** to run without a statement journal if there are no indexes on the
+        ** table.
+        */
+        Trigger *pTrigger = 0;
+        if( db->flags&SQLITE_RecTriggers ){
+          pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
+        }
+        if( pTrigger || sqlite3FkRequired(pParse, pTab, 0, 0) ){
+          sqlite3MultiWrite(pParse);
+          sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur,
+                                   regNewData, 1, 0, OE_Replace, 1, -1);
+        }else{
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+          if( HasRowid(pTab) ){
+            /* This OP_Delete opcode fires the pre-update-hook only. It does
+            ** not modify the b-tree. It is more efficient to let the coming
+            ** OP_Insert replace the existing entry than it is to delete the
+            ** existing entry and then insert a new one. */
+            sqlite3VdbeAddOp2(v, OP_Delete, iDataCur, OPFLAG_ISNOOP);
+            sqlite3VdbeChangeP4(v, -1, (char *)pTab, P4_TABLE);
+          }
+#endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
+          if( pTab->pIndex ){
+            sqlite3MultiWrite(pParse);
+            sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur,0,-1);
+          }
+        }
+        seenReplace = 1;
+        break;
+      }
+      case OE_Ignore: {
+        /*assert( seenReplace==0 );*/
+        sqlite3VdbeGoto(v, ignoreDest);
+        break;
+      }
+    }
+    sqlite3VdbeResolveLabel(v, addrRowidOk);
+    if( ipkTop ){
+      ipkBottom = sqlite3VdbeAddOp0(v, OP_Goto);
+      sqlite3VdbeJumpHere(v, ipkTop);
+    }
+  }
+
+  /* Test all UNIQUE constraints by creating entries for each UNIQUE
+  ** index and making sure that duplicate entries do not already exist.
+  ** Compute the revised record entries for indices as we go.
+  **
+  ** This loop also handles the case of the PRIMARY KEY index for a
+  ** WITHOUT ROWID table.
+  */
+  for(ix=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, ix++){
+    int regIdx;          /* Range of registers hold conent for pIdx */
+    int regR;            /* Range of registers holding conflicting PK */
+    int iThisCur;        /* Cursor for this UNIQUE index */
+    int addrUniqueOk;    /* Jump here if the UNIQUE constraint is satisfied */
+
+    if( aRegIdx[ix]==0 ) continue;  /* Skip indices that do not change */
+    if( bAffinityDone==0 ){
+      sqlite3TableAffinity(v, pTab, regNewData+1);
+      bAffinityDone = 1;
+    }
+    iThisCur = iIdxCur+ix;
+    addrUniqueOk = sqlite3VdbeMakeLabel(v);
+
+    /* Skip partial indices for which the WHERE clause is not true */
+    if( pIdx->pPartIdxWhere ){
+      sqlite3VdbeAddOp2(v, OP_Null, 0, aRegIdx[ix]);
+      pParse->ckBase = regNewData+1;
+      sqlite3ExprIfFalseDup(pParse, pIdx->pPartIdxWhere, addrUniqueOk,
+                            SQLITE_JUMPIFNULL);
+      pParse->ckBase = 0;
+    }
+
+    /* Create a record for this index entry as it should appear after
+    ** the insert or update.  Store that record in the aRegIdx[ix] register
+    */
+    regIdx = sqlite3GetTempRange(pParse, pIdx->nColumn);
+    for(i=0; i<pIdx->nColumn; i++){
+      int iField = pIdx->aiColumn[i];
+      int x;
+      if( iField==XN_EXPR ){
+        pParse->ckBase = regNewData+1;
+        sqlite3ExprCodeCopy(pParse, pIdx->aColExpr->a[i].pExpr, regIdx+i);
+        pParse->ckBase = 0;
+        VdbeComment((v, "%s column %d", pIdx->zName, i));
+      }else{
+        if( iField==XN_ROWID || iField==pTab->iPKey ){
+          if( regRowid==regIdx+i ) continue; /* ROWID already in regIdx+i */
+          x = regNewData;
+          regRowid =  pIdx->pPartIdxWhere ? -1 : regIdx+i;
+        }else{
+          x = iField + regNewData + 1;
+        }
+        sqlite3VdbeAddOp2(v, iField<0 ? OP_IntCopy : OP_SCopy, x, regIdx+i);
+        VdbeComment((v, "%s", iField<0 ? "rowid" : pTab->aCol[iField].zName));
+      }
+    }
+    sqlite3VdbeAddOp3(v, OP_MakeRecord, regIdx, pIdx->nColumn, aRegIdx[ix]);
+    VdbeComment((v, "for %s", pIdx->zName));
+    sqlite3ExprCacheAffinityChange(pParse, regIdx, pIdx->nColumn);
+
+    /* In an UPDATE operation, if this index is the PRIMARY KEY index 
+    ** of a WITHOUT ROWID table and there has been no change the
+    ** primary key, then no collision is possible.  The collision detection
+    ** logic below can all be skipped. */
+    if( isUpdate && pPk==pIdx && pkChng==0 ){
+      sqlite3VdbeResolveLabel(v, addrUniqueOk);
+      continue;
+    }
+
+    /* Find out what action to take in case there is a uniqueness conflict */
+    onError = pIdx->onError;
+    if( onError==OE_None ){ 
+      sqlite3ReleaseTempRange(pParse, regIdx, pIdx->nColumn);
+      sqlite3VdbeResolveLabel(v, addrUniqueOk);
+      continue;  /* pIdx is not a UNIQUE index */
+    }
+    if( overrideError!=OE_Default ){
+      onError = overrideError;
+    }else if( onError==OE_Default ){
+      onError = OE_Abort;
+    }
+    
+    /* Check to see if the new index entry will be unique */
+    sqlite3VdbeAddOp4Int(v, OP_NoConflict, iThisCur, addrUniqueOk,
+                         regIdx, pIdx->nKeyCol); VdbeCoverage(v);
+
+    /* Generate code to handle collisions */
+    regR = (pIdx==pPk) ? regIdx : sqlite3GetTempRange(pParse, nPkField);
+    if( isUpdate || onError==OE_Replace ){
+      if( HasRowid(pTab) ){
+        sqlite3VdbeAddOp2(v, OP_IdxRowid, iThisCur, regR);
+        /* Conflict only if the rowid of the existing index entry
+        ** is different from old-rowid */
+        if( isUpdate ){
+          sqlite3VdbeAddOp3(v, OP_Eq, regR, addrUniqueOk, regOldData);
+          sqlite3VdbeChangeP5(v, SQLITE_NOTNULL);
+          VdbeCoverage(v);
+        }
+      }else{
+        int x;
+        /* Extract the PRIMARY KEY from the end of the index entry and
+        ** store it in registers regR..regR+nPk-1 */
+        if( pIdx!=pPk ){
+          for(i=0; i<pPk->nKeyCol; i++){
+            assert( pPk->aiColumn[i]>=0 );
+            x = sqlite3ColumnOfIndex(pIdx, pPk->aiColumn[i]);
+            sqlite3VdbeAddOp3(v, OP_Column, iThisCur, x, regR+i);
+            VdbeComment((v, "%s.%s", pTab->zName,
+                         pTab->aCol[pPk->aiColumn[i]].zName));
+          }
+        }
+        if( isUpdate ){
+          /* If currently processing the PRIMARY KEY of a WITHOUT ROWID 
+          ** table, only conflict if the new PRIMARY KEY values are actually
+          ** different from the old.
+          **
+          ** For a UNIQUE index, only conflict if the PRIMARY KEY values
+          ** of the matched index row are different from the original PRIMARY
+          ** KEY values of this row before the update.  */
+          int addrJump = sqlite3VdbeCurrentAddr(v)+pPk->nKeyCol;
+          int op = OP_Ne;
+          int regCmp = (IsPrimaryKeyIndex(pIdx) ? regIdx : regR);
+  
+          for(i=0; i<pPk->nKeyCol; i++){
+            char *p4 = (char*)sqlite3LocateCollSeq(pParse, pPk->azColl[i]);
+            x = pPk->aiColumn[i];
+            assert( x>=0 );
+            if( i==(pPk->nKeyCol-1) ){
+              addrJump = addrUniqueOk;
+              op = OP_Eq;
+            }
+            sqlite3VdbeAddOp4(v, op, 
+                regOldData+1+x, addrJump, regCmp+i, p4, P4_COLLSEQ
+            );
+            sqlite3VdbeChangeP5(v, SQLITE_NOTNULL);
+            VdbeCoverageIf(v, op==OP_Eq);
+            VdbeCoverageIf(v, op==OP_Ne);
+          }
+        }
+      }
+    }
+
+    /* Generate code that executes if the new index entry is not unique */
+    assert( onError==OE_Rollback || onError==OE_Abort || onError==OE_Fail
+        || onError==OE_Ignore || onError==OE_Replace );
+    switch( onError ){
+      case OE_Rollback:
+      case OE_Abort:
+      case OE_Fail: {
+        sqlite3UniqueConstraint(pParse, onError, pIdx);
+        break;
+      }
+      case OE_Ignore: {
+        sqlite3VdbeGoto(v, ignoreDest);
+        break;
+      }
+      default: {
+        Trigger *pTrigger = 0;
+        assert( onError==OE_Replace );
+        sqlite3MultiWrite(pParse);
+        if( db->flags&SQLITE_RecTriggers ){
+          pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
+        }
+        sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur,
+            regR, nPkField, 0, OE_Replace,
+            (pIdx==pPk ? ONEPASS_SINGLE : ONEPASS_OFF), -1);
+        seenReplace = 1;
+        break;
+      }
+    }
+    sqlite3VdbeResolveLabel(v, addrUniqueOk);
+    sqlite3ReleaseTempRange(pParse, regIdx, pIdx->nColumn);
+    if( regR!=regIdx ) sqlite3ReleaseTempRange(pParse, regR, nPkField);
+  }
+  if( ipkTop ){
+    sqlite3VdbeGoto(v, ipkTop+1);
+    sqlite3VdbeJumpHere(v, ipkBottom);
+  }
+  
+  *pbMayReplace = seenReplace;
+  VdbeModuleComment((v, "END: GenCnstCks(%d)", seenReplace));
+}
+
+/*
+** This routine generates code to finish the INSERT or UPDATE operation
+** that was started by a prior call to sqlite3GenerateConstraintChecks.
+** A consecutive range of registers starting at regNewData contains the
+** rowid and the content to be inserted.
+**
+** The arguments to this routine should be the same as the first six
+** arguments to sqlite3GenerateConstraintChecks.
+*/
+SQLITE_PRIVATE void sqlite3CompleteInsertion(
+  Parse *pParse,      /* The parser context */
+  Table *pTab,        /* the table into which we are inserting */
+  int iDataCur,       /* Cursor of the canonical data source */
+  int iIdxCur,        /* First index cursor */
+  int regNewData,     /* Range of content */
+  int *aRegIdx,       /* Register used by each index.  0 for unused indices */
+  int isUpdate,       /* True for UPDATE, False for INSERT */
+  int appendBias,     /* True if this is likely to be an append */
+  int useSeekResult   /* True to set the USESEEKRESULT flag on OP_[Idx]Insert */
+){
+  Vdbe *v;            /* Prepared statements under construction */
+  Index *pIdx;        /* An index being inserted or updated */
+  u8 pik_flags;       /* flag values passed to the btree insert */
+  int regData;        /* Content registers (after the rowid) */
+  int regRec;         /* Register holding assembled record for the table */
+  int i;              /* Loop counter */
+  u8 bAffinityDone = 0; /* True if OP_Affinity has been run already */
+
+  v = sqlite3GetVdbe(pParse);
+  assert( v!=0 );
+  assert( pTab->pSelect==0 );  /* This table is not a VIEW */
+  for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
+    if( aRegIdx[i]==0 ) continue;
+    bAffinityDone = 1;
+    if( pIdx->pPartIdxWhere ){
+      sqlite3VdbeAddOp2(v, OP_IsNull, aRegIdx[i], sqlite3VdbeCurrentAddr(v)+2);
+      VdbeCoverage(v);
+    }
+    sqlite3VdbeAddOp2(v, OP_IdxInsert, iIdxCur+i, aRegIdx[i]);
+    pik_flags = 0;
+    if( useSeekResult ) pik_flags = OPFLAG_USESEEKRESULT;
+    if( IsPrimaryKeyIndex(pIdx) && !HasRowid(pTab) ){
+      assert( pParse->nested==0 );
+      pik_flags |= OPFLAG_NCHANGE;
+    }
+    sqlite3VdbeChangeP5(v, pik_flags);
+  }
+  if( !HasRowid(pTab) ) return;
+  regData = regNewData + 1;
+  regRec = sqlite3GetTempReg(pParse);
+  sqlite3VdbeAddOp3(v, OP_MakeRecord, regData, pTab->nCol, regRec);
+  if( !bAffinityDone ) sqlite3TableAffinity(v, pTab, 0);
+  sqlite3ExprCacheAffinityChange(pParse, regData, pTab->nCol);
+  if( pParse->nested ){
+    pik_flags = 0;
+  }else{
+    pik_flags = OPFLAG_NCHANGE;
+    pik_flags |= (isUpdate?OPFLAG_ISUPDATE:OPFLAG_LASTROWID);
+  }
+  if( appendBias ){
+    pik_flags |= OPFLAG_APPEND;
+  }
+  if( useSeekResult ){
+    pik_flags |= OPFLAG_USESEEKRESULT;
+  }
+  sqlite3VdbeAddOp3(v, OP_Insert, iDataCur, regRec, regNewData);
+  if( !pParse->nested ){
+    sqlite3VdbeChangeP4(v, -1, (char *)pTab, P4_TABLE);
+  }
+  sqlite3VdbeChangeP5(v, pik_flags);
+}
+
+/*
+** Allocate cursors for the pTab table and all its indices and generate
+** code to open and initialized those cursors.
+**
+** The cursor for the object that contains the complete data (normally
+** the table itself, but the PRIMARY KEY index in the case of a WITHOUT
+** ROWID table) is returned in *piDataCur.  The first index cursor is
+** returned in *piIdxCur.  The number of indices is returned.
+**
+** Use iBase as the first cursor (either the *piDataCur for rowid tables
+** or the first index for WITHOUT ROWID tables) if it is non-negative.
+** If iBase is negative, then allocate the next available cursor.
+**
+** For a rowid table, *piDataCur will be exactly one less than *piIdxCur.
+** For a WITHOUT ROWID table, *piDataCur will be somewhere in the range
+** of *piIdxCurs, depending on where the PRIMARY KEY index appears on the
+** pTab->pIndex list.
+**
+** If pTab is a virtual table, then this routine is a no-op and the
+** *piDataCur and *piIdxCur values are left uninitialized.
+*/
+SQLITE_PRIVATE int sqlite3OpenTableAndIndices(
+  Parse *pParse,   /* Parsing context */
+  Table *pTab,     /* Table to be opened */
+  int op,          /* OP_OpenRead or OP_OpenWrite */
+  u8 p5,           /* P5 value for OP_Open* opcodes (except on WITHOUT ROWID) */
+  int iBase,       /* Use this for the table cursor, if there is one */
+  u8 *aToOpen,     /* If not NULL: boolean for each table and index */
+  int *piDataCur,  /* Write the database source cursor number here */
+  int *piIdxCur    /* Write the first index cursor number here */
+){
+  int i;
+  int iDb;
+  int iDataCur;
+  Index *pIdx;
+  Vdbe *v;
+
+  assert( op==OP_OpenRead || op==OP_OpenWrite );
+  assert( op==OP_OpenWrite || p5==0 );
+  if( IsVirtual(pTab) ){
+    /* This routine is a no-op for virtual tables. Leave the output
+    ** variables *piDataCur and *piIdxCur uninitialized so that valgrind
+    ** can detect if they are used by mistake in the caller. */
+    return 0;
+  }
+  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
+  v = sqlite3GetVdbe(pParse);
+  assert( v!=0 );
+  if( iBase<0 ) iBase = pParse->nTab;
+  iDataCur = iBase++;
+  if( piDataCur ) *piDataCur = iDataCur;
+  if( HasRowid(pTab) && (aToOpen==0 || aToOpen[0]) ){
+    sqlite3OpenTable(pParse, iDataCur, iDb, pTab, op);
+  }else{
+    sqlite3TableLock(pParse, iDb, pTab->tnum, op==OP_OpenWrite, pTab->zName);
+  }
+  if( piIdxCur ) *piIdxCur = iBase;
+  for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
+    int iIdxCur = iBase++;
+    assert( pIdx->pSchema==pTab->pSchema );
+    if( IsPrimaryKeyIndex(pIdx) && !HasRowid(pTab) ){
+      if( piDataCur ) *piDataCur = iIdxCur;
+      p5 = 0;
+    }
+    if( aToOpen==0 || aToOpen[i+1] ){
+      sqlite3VdbeAddOp3(v, op, iIdxCur, pIdx->tnum, iDb);
+      sqlite3VdbeSetP4KeyInfo(pParse, pIdx);
+      sqlite3VdbeChangeP5(v, p5);
+      VdbeComment((v, "%s", pIdx->zName));
+    }
+  }
+  if( iBase>pParse->nTab ) pParse->nTab = iBase;
+  return i;
+}
+
+
+#ifdef SQLITE_TEST
+/*
+** The following global variable is incremented whenever the
+** transfer optimization is used.  This is used for testing
+** purposes only - to make sure the transfer optimization really
+** is happening when it is supposed to.
+*/
+SQLITE_API int sqlite3_xferopt_count;
+#endif /* SQLITE_TEST */
+
+
+#ifndef SQLITE_OMIT_XFER_OPT
+/*
+** Check to see if index pSrc is compatible as a source of data
+** for index pDest in an insert transfer optimization.  The rules
+** for a compatible index:
+**
+**    *   The index is over the same set of columns
+**    *   The same DESC and ASC markings occurs on all columns
+**    *   The same onError processing (OE_Abort, OE_Ignore, etc)
+**    *   The same collating sequence on each column
+**    *   The index has the exact same WHERE clause
+*/
+static int xferCompatibleIndex(Index *pDest, Index *pSrc){
+  int i;
+  assert( pDest && pSrc );
+  assert( pDest->pTable!=pSrc->pTable );
+  if( pDest->nKeyCol!=pSrc->nKeyCol ){
+    return 0;   /* Different number of columns */
+  }
+  if( pDest->onError!=pSrc->onError ){
+    return 0;   /* Different conflict resolution strategies */
+  }
+  for(i=0; i<pSrc->nKeyCol; i++){
+    if( pSrc->aiColumn[i]!=pDest->aiColumn[i] ){
+      return 0;   /* Different columns indexed */
+    }
+    if( pSrc->aiColumn[i]==XN_EXPR ){
+      assert( pSrc->aColExpr!=0 && pDest->aColExpr!=0 );
+      if( sqlite3ExprCompare(pSrc->aColExpr->a[i].pExpr,
+                             pDest->aColExpr->a[i].pExpr, -1)!=0 ){
+        return 0;   /* Different expressions in the index */
+      }
+    }
+    if( pSrc->aSortOrder[i]!=pDest->aSortOrder[i] ){
+      return 0;   /* Different sort orders */
+    }
+    if( sqlite3_stricmp(pSrc->azColl[i],pDest->azColl[i])!=0 ){
+      return 0;   /* Different collating sequences */
+    }
+  }
+  if( sqlite3ExprCompare(pSrc->pPartIdxWhere, pDest->pPartIdxWhere, -1) ){
+    return 0;     /* Different WHERE clauses */
+  }
+
+  /* If no test above fails then the indices must be compatible */
+  return 1;
+}
+
+/*
+** Attempt the transfer optimization on INSERTs of the form
+**
+**     INSERT INTO tab1 SELECT * FROM tab2;
+**
+** The xfer optimization transfers raw records from tab2 over to tab1.  
+** Columns are not decoded and reassembled, which greatly improves
+** performance.  Raw index records are transferred in the same way.
+**
+** The xfer optimization is only attempted if tab1 and tab2 are compatible.
+** There are lots of rules for determining compatibility - see comments
+** embedded in the code for details.
+**
+** This routine returns TRUE if the optimization is guaranteed to be used.
+** Sometimes the xfer optimization will only work if the destination table
+** is empty - a factor that can only be determined at run-time.  In that
+** case, this routine generates code for the xfer optimization but also
+** does a test to see if the destination table is empty and jumps over the
+** xfer optimization code if the test fails.  In that case, this routine
+** returns FALSE so that the caller will know to go ahead and generate
+** an unoptimized transfer.  This routine also returns FALSE if there
+** is no chance that the xfer optimization can be applied.
+**
+** This optimization is particularly useful at making VACUUM run faster.
+*/
+static int xferOptimization(
+  Parse *pParse,        /* Parser context */
+  Table *pDest,         /* The table we are inserting into */
+  Select *pSelect,      /* A SELECT statement to use as the data source */
+  int onError,          /* How to handle constraint errors */
+  int iDbDest           /* The database of pDest */
+){
+  sqlite3 *db = pParse->db;
+  ExprList *pEList;                /* The result set of the SELECT */
+  Table *pSrc;                     /* The table in the FROM clause of SELECT */
+  Index *pSrcIdx, *pDestIdx;       /* Source and destination indices */
+  struct SrcList_item *pItem;      /* An element of pSelect->pSrc */
+  int i;                           /* Loop counter */
+  int iDbSrc;                      /* The database of pSrc */
+  int iSrc, iDest;                 /* Cursors from source and destination */
+  int addr1, addr2;                /* Loop addresses */
+  int emptyDestTest = 0;           /* Address of test for empty pDest */
+  int emptySrcTest = 0;            /* Address of test for empty pSrc */
+  Vdbe *v;                         /* The VDBE we are building */
+  int regAutoinc;                  /* Memory register used by AUTOINC */
+  int destHasUniqueIdx = 0;        /* True if pDest has a UNIQUE index */
+  int regData, regRowid;           /* Registers holding data and rowid */
+
+  if( pSelect==0 ){
+    return 0;   /* Must be of the form  INSERT INTO ... SELECT ... */
+  }
+  if( pParse->pWith || pSelect->pWith ){
+    /* Do not attempt to process this query if there are an WITH clauses
+    ** attached to it. Proceeding may generate a false "no such table: xxx"
+    ** error if pSelect reads from a CTE named "xxx".  */
+    return 0;
+  }
+  if( sqlite3TriggerList(pParse, pDest) ){
+    return 0;   /* tab1 must not have triggers */
+  }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  if( pDest->tabFlags & TF_Virtual ){
+    return 0;   /* tab1 must not be a virtual table */
+  }
+#endif
+  if( onError==OE_Default ){
+    if( pDest->iPKey>=0 ) onError = pDest->keyConf;
+    if( onError==OE_Default ) onError = OE_Abort;
+  }
+  assert(pSelect->pSrc);   /* allocated even if there is no FROM clause */
+  if( pSelect->pSrc->nSrc!=1 ){
+    return 0;   /* FROM clause must have exactly one term */
+  }
+  if( pSelect->pSrc->a[0].pSelect ){
+    return 0;   /* FROM clause cannot contain a subquery */
+  }
+  if( pSelect->pWhere ){
+    return 0;   /* SELECT may not have a WHERE clause */
+  }
+  if( pSelect->pOrderBy ){
+    return 0;   /* SELECT may not have an ORDER BY clause */
+  }
+  /* Do not need to test for a HAVING clause.  If HAVING is present but
+  ** there is no ORDER BY, we will get an error. */
+  if( pSelect->pGroupBy ){
+    return 0;   /* SELECT may not have a GROUP BY clause */
+  }
+  if( pSelect->pLimit ){
+    return 0;   /* SELECT may not have a LIMIT clause */
+  }
+  assert( pSelect->pOffset==0 );  /* Must be so if pLimit==0 */
+  if( pSelect->pPrior ){
+    return 0;   /* SELECT may not be a compound query */
+  }
+  if( pSelect->selFlags & SF_Distinct ){
+    return 0;   /* SELECT may not be DISTINCT */
+  }
+  pEList = pSelect->pEList;
+  assert( pEList!=0 );
+  if( pEList->nExpr!=1 ){
+    return 0;   /* The result set must have exactly one column */
+  }
+  assert( pEList->a[0].pExpr );
+  if( pEList->a[0].pExpr->op!=TK_ASTERISK ){
+    return 0;   /* The result set must be the special operator "*" */
+  }
+
+  /* At this point we have established that the statement is of the
+  ** correct syntactic form to participate in this optimization.  Now
+  ** we have to check the semantics.
+  */
+  pItem = pSelect->pSrc->a;
+  pSrc = sqlite3LocateTableItem(pParse, 0, pItem);
+  if( pSrc==0 ){
+    return 0;   /* FROM clause does not contain a real table */
+  }
+  if( pSrc==pDest ){
+    return 0;   /* tab1 and tab2 may not be the same table */
+  }
+  if( HasRowid(pDest)!=HasRowid(pSrc) ){
+    return 0;   /* source and destination must both be WITHOUT ROWID or not */
+  }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  if( pSrc->tabFlags & TF_Virtual ){
+    return 0;   /* tab2 must not be a virtual table */
+  }
+#endif
+  if( pSrc->pSelect ){
+    return 0;   /* tab2 may not be a view */
+  }
+  if( pDest->nCol!=pSrc->nCol ){
+    return 0;   /* Number of columns must be the same in tab1 and tab2 */
+  }
+  if( pDest->iPKey!=pSrc->iPKey ){
+    return 0;   /* Both tables must have the same INTEGER PRIMARY KEY */
+  }
+  for(i=0; i<pDest->nCol; i++){
+    Column *pDestCol = &pDest->aCol[i];
+    Column *pSrcCol = &pSrc->aCol[i];
+#ifdef SQLITE_ENABLE_HIDDEN_COLUMNS
+    if( (db->flags & SQLITE_Vacuum)==0 
+     && (pDestCol->colFlags | pSrcCol->colFlags) & COLFLAG_HIDDEN 
+    ){
+      return 0;    /* Neither table may have __hidden__ columns */
+    }
+#endif
+    if( pDestCol->affinity!=pSrcCol->affinity ){
+      return 0;    /* Affinity must be the same on all columns */
+    }
+    if( sqlite3_stricmp(pDestCol->zColl, pSrcCol->zColl)!=0 ){
+      return 0;    /* Collating sequence must be the same on all columns */
+    }
+    if( pDestCol->notNull && !pSrcCol->notNull ){
+      return 0;    /* tab2 must be NOT NULL if tab1 is */
+    }
+    /* Default values for second and subsequent columns need to match. */
+    if( i>0 ){
+      assert( pDestCol->pDflt==0 || pDestCol->pDflt->op==TK_SPAN );
+      assert( pSrcCol->pDflt==0 || pSrcCol->pDflt->op==TK_SPAN );
+      if( (pDestCol->pDflt==0)!=(pSrcCol->pDflt==0) 
+       || (pDestCol->pDflt && strcmp(pDestCol->pDflt->u.zToken,
+                                       pSrcCol->pDflt->u.zToken)!=0)
+      ){
+        return 0;    /* Default values must be the same for all columns */
+      }
+    }
+  }
+  for(pDestIdx=pDest->pIndex; pDestIdx; pDestIdx=pDestIdx->pNext){
+    if( IsUniqueIndex(pDestIdx) ){
+      destHasUniqueIdx = 1;
+    }
+    for(pSrcIdx=pSrc->pIndex; pSrcIdx; pSrcIdx=pSrcIdx->pNext){
+      if( xferCompatibleIndex(pDestIdx, pSrcIdx) ) break;
+    }
+    if( pSrcIdx==0 ){
+      return 0;    /* pDestIdx has no corresponding index in pSrc */
+    }
+  }
+#ifndef SQLITE_OMIT_CHECK
+  if( pDest->pCheck && sqlite3ExprListCompare(pSrc->pCheck,pDest->pCheck,-1) ){
+    return 0;   /* Tables have different CHECK constraints.  Ticket #2252 */
+  }
+#endif
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+  /* Disallow the transfer optimization if the destination table constains
+  ** any foreign key constraints.  This is more restrictive than necessary.
+  ** But the main beneficiary of the transfer optimization is the VACUUM 
+  ** command, and the VACUUM command disables foreign key constraints.  So
+  ** the extra complication to make this rule less restrictive is probably
+  ** not worth the effort.  Ticket [6284df89debdfa61db8073e062908af0c9b6118e]
+  */
+  if( (db->flags & SQLITE_ForeignKeys)!=0 && pDest->pFKey!=0 ){
+    return 0;
+  }
+#endif
+  if( (db->flags & SQLITE_CountRows)!=0 ){
+    return 0;  /* xfer opt does not play well with PRAGMA count_changes */
+  }
+
+  /* If we get this far, it means that the xfer optimization is at
+  ** least a possibility, though it might only work if the destination
+  ** table (tab1) is initially empty.
+  */
+#ifdef SQLITE_TEST
+  sqlite3_xferopt_count++;
+#endif
+  iDbSrc = sqlite3SchemaToIndex(db, pSrc->pSchema);
+  v = sqlite3GetVdbe(pParse);
+  sqlite3CodeVerifySchema(pParse, iDbSrc);
+  iSrc = pParse->nTab++;
+  iDest = pParse->nTab++;
+  regAutoinc = autoIncBegin(pParse, iDbDest, pDest);
+  regData = sqlite3GetTempReg(pParse);
+  regRowid = sqlite3GetTempReg(pParse);
+  sqlite3OpenTable(pParse, iDest, iDbDest, pDest, OP_OpenWrite);
+  assert( HasRowid(pDest) || destHasUniqueIdx );
+  if( (db->flags & SQLITE_Vacuum)==0 && (
+      (pDest->iPKey<0 && pDest->pIndex!=0)          /* (1) */
+   || destHasUniqueIdx                              /* (2) */
+   || (onError!=OE_Abort && onError!=OE_Rollback)   /* (3) */
+  )){
+    /* In some circumstances, we are able to run the xfer optimization
+    ** only if the destination table is initially empty. Unless the
+    ** SQLITE_Vacuum flag is set, this block generates code to make
+    ** that determination. If SQLITE_Vacuum is set, then the destination
+    ** table is always empty.
+    **
+    ** Conditions under which the destination must be empty:
+    **
+    ** (1) There is no INTEGER PRIMARY KEY but there are indices.
+    **     (If the destination is not initially empty, the rowid fields
+    **     of index entries might need to change.)
+    **
+    ** (2) The destination has a unique index.  (The xfer optimization 
+    **     is unable to test uniqueness.)
+    **
+    ** (3) onError is something other than OE_Abort and OE_Rollback.
+    */
+    addr1 = sqlite3VdbeAddOp2(v, OP_Rewind, iDest, 0); VdbeCoverage(v);
+    emptyDestTest = sqlite3VdbeAddOp0(v, OP_Goto);
+    sqlite3VdbeJumpHere(v, addr1);
+  }
+  if( HasRowid(pSrc) ){
+    sqlite3OpenTable(pParse, iSrc, iDbSrc, pSrc, OP_OpenRead);
+    emptySrcTest = sqlite3VdbeAddOp2(v, OP_Rewind, iSrc, 0); VdbeCoverage(v);
+    if( pDest->iPKey>=0 ){
+      addr1 = sqlite3VdbeAddOp2(v, OP_Rowid, iSrc, regRowid);
+      addr2 = sqlite3VdbeAddOp3(v, OP_NotExists, iDest, 0, regRowid);
+      VdbeCoverage(v);
+      sqlite3RowidConstraint(pParse, onError, pDest);
+      sqlite3VdbeJumpHere(v, addr2);
+      autoIncStep(pParse, regAutoinc, regRowid);
+    }else if( pDest->pIndex==0 ){
+      addr1 = sqlite3VdbeAddOp2(v, OP_NewRowid, iDest, regRowid);
+    }else{
+      addr1 = sqlite3VdbeAddOp2(v, OP_Rowid, iSrc, regRowid);
+      assert( (pDest->tabFlags & TF_Autoincrement)==0 );
+    }
+    sqlite3VdbeAddOp2(v, OP_RowData, iSrc, regData);
+    sqlite3VdbeAddOp4(v, OP_Insert, iDest, regData, regRowid,
+                      (char*)pDest, P4_TABLE);
+    sqlite3VdbeChangeP5(v, OPFLAG_NCHANGE|OPFLAG_LASTROWID|OPFLAG_APPEND);
+    sqlite3VdbeAddOp2(v, OP_Next, iSrc, addr1); VdbeCoverage(v);
+    sqlite3VdbeAddOp2(v, OP_Close, iSrc, 0);
+    sqlite3VdbeAddOp2(v, OP_Close, iDest, 0);
+  }else{
+    sqlite3TableLock(pParse, iDbDest, pDest->tnum, 1, pDest->zName);
+    sqlite3TableLock(pParse, iDbSrc, pSrc->tnum, 0, pSrc->zName);
+  }
+  for(pDestIdx=pDest->pIndex; pDestIdx; pDestIdx=pDestIdx->pNext){
+    u8 idxInsFlags = 0;
+    for(pSrcIdx=pSrc->pIndex; ALWAYS(pSrcIdx); pSrcIdx=pSrcIdx->pNext){
+      if( xferCompatibleIndex(pDestIdx, pSrcIdx) ) break;
+    }
+    assert( pSrcIdx );
+    sqlite3VdbeAddOp3(v, OP_OpenRead, iSrc, pSrcIdx->tnum, iDbSrc);
+    sqlite3VdbeSetP4KeyInfo(pParse, pSrcIdx);
+    VdbeComment((v, "%s", pSrcIdx->zName));
+    sqlite3VdbeAddOp3(v, OP_OpenWrite, iDest, pDestIdx->tnum, iDbDest);
+    sqlite3VdbeSetP4KeyInfo(pParse, pDestIdx);
+    sqlite3VdbeChangeP5(v, OPFLAG_BULKCSR);
+    VdbeComment((v, "%s", pDestIdx->zName));
+    addr1 = sqlite3VdbeAddOp2(v, OP_Rewind, iSrc, 0); VdbeCoverage(v);
+    sqlite3VdbeAddOp2(v, OP_RowKey, iSrc, regData);
+    if( db->flags & SQLITE_Vacuum ){
+      /* This INSERT command is part of a VACUUM operation, which guarantees
+      ** that the destination table is empty. If all indexed columns use
+      ** collation sequence BINARY, then it can also be assumed that the
+      ** index will be populated by inserting keys in strictly sorted 
+      ** order. In this case, instead of seeking within the b-tree as part
+      ** of every OP_IdxInsert opcode, an OP_Last is added before the
+      ** OP_IdxInsert to seek to the point within the b-tree where each key 
+      ** should be inserted. This is faster.
+      **
+      ** If any of the indexed columns use a collation sequence other than
+      ** BINARY, this optimization is disabled. This is because the user 
+      ** might change the definition of a collation sequence and then run
+      ** a VACUUM command. In that case keys may not be written in strictly
+      ** sorted order.  */
+      for(i=0; i<pSrcIdx->nColumn; i++){
+        const char *zColl = pSrcIdx->azColl[i];
+        assert( sqlite3_stricmp(sqlite3StrBINARY, zColl)!=0
+                    || sqlite3StrBINARY==zColl );
+        if( sqlite3_stricmp(sqlite3StrBINARY, zColl) ) break;
+      }
+      if( i==pSrcIdx->nColumn ){
+        idxInsFlags = OPFLAG_USESEEKRESULT;
+        sqlite3VdbeAddOp3(v, OP_Last, iDest, 0, -1);
+      }
+    }
+    if( !HasRowid(pSrc) && pDestIdx->idxType==2 ){
+      idxInsFlags |= OPFLAG_NCHANGE;
+    }
+    sqlite3VdbeAddOp3(v, OP_IdxInsert, iDest, regData, 1);
+    sqlite3VdbeChangeP5(v, idxInsFlags);
+    sqlite3VdbeAddOp2(v, OP_Next, iSrc, addr1+1); VdbeCoverage(v);
+    sqlite3VdbeJumpHere(v, addr1);
+    sqlite3VdbeAddOp2(v, OP_Close, iSrc, 0);
+    sqlite3VdbeAddOp2(v, OP_Close, iDest, 0);
+  }
+  if( emptySrcTest ) sqlite3VdbeJumpHere(v, emptySrcTest);
+  sqlite3ReleaseTempReg(pParse, regRowid);
+  sqlite3ReleaseTempReg(pParse, regData);
+  if( emptyDestTest ){
+    sqlite3AutoincrementEnd(pParse);
+    sqlite3VdbeAddOp2(v, OP_Halt, SQLITE_OK, 0);
+    sqlite3VdbeJumpHere(v, emptyDestTest);
+    sqlite3VdbeAddOp2(v, OP_Close, iDest, 0);
+    return 0;
+  }else{
+    return 1;
+  }
+}
+#endif /* SQLITE_OMIT_XFER_OPT */
+
+/************** End of insert.c **********************************************/
+/************** Begin file legacy.c ******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** Main file for the SQLite library.  The routines in this file
+** implement the programmer interface to the library.  Routines in
+** other files are for internal use by SQLite and should not be
+** accessed by users of the library.
+*/
+
+/* #include "sqliteInt.h" */
+
+/*
+** Execute SQL code.  Return one of the SQLITE_ success/failure
+** codes.  Also write an error message into memory obtained from
+** malloc() and make *pzErrMsg point to that message.
+**
+** If the SQL is a query, then for each row in the query result
+** the xCallback() function is called.  pArg becomes the first
+** argument to xCallback().  If xCallback=NULL then no callback
+** is invoked, even for queries.
+*/
+SQLITE_API int sqlite3_exec(
+  sqlite3 *db,                /* The database on which the SQL executes */
+  const char *zSql,           /* The SQL to be executed */
+  sqlite3_callback xCallback, /* Invoke this callback routine */
+  void *pArg,                 /* First argument to xCallback() */
+  char **pzErrMsg             /* Write error messages here */
+){
+  int rc = SQLITE_OK;         /* Return code */
+  const char *zLeftover;      /* Tail of unprocessed SQL */
+  sqlite3_stmt *pStmt = 0;    /* The current SQL statement */
+  char **azCols = 0;          /* Names of result columns */
+  int callbackIsInit;         /* True if callback data is initialized */
+
+  if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
+  if( zSql==0 ) zSql = "";
+
+  sqlite3_mutex_enter(db->mutex);
+  sqlite3Error(db, SQLITE_OK);
+  while( rc==SQLITE_OK && zSql[0] ){
+    int nCol;
+    char **azVals = 0;
+
+    pStmt = 0;
+    rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, &zLeftover);
+    assert( rc==SQLITE_OK || pStmt==0 );
+    if( rc!=SQLITE_OK ){
+      continue;
+    }
+    if( !pStmt ){
+      /* this happens for a comment or white-space */
+      zSql = zLeftover;
+      continue;
+    }
+
+    callbackIsInit = 0;
+    nCol = sqlite3_column_count(pStmt);
+
+    while( 1 ){
+      int i;
+      rc = sqlite3_step(pStmt);
+
+      /* Invoke the callback function if required */
+      if( xCallback && (SQLITE_ROW==rc || 
+          (SQLITE_DONE==rc && !callbackIsInit
+                           && db->flags&SQLITE_NullCallback)) ){
+        if( !callbackIsInit ){
+          azCols = sqlite3DbMallocZero(db, 2*nCol*sizeof(const char*) + 1);
+          if( azCols==0 ){
+            goto exec_out;
+          }
+          for(i=0; i<nCol; i++){
+            azCols[i] = (char *)sqlite3_column_name(pStmt, i);
+            /* sqlite3VdbeSetColName() installs column names as UTF8
+            ** strings so there is no way for sqlite3_column_name() to fail. */
+            assert( azCols[i]!=0 );
+          }
+          callbackIsInit = 1;
+        }
+        if( rc==SQLITE_ROW ){
+          azVals = &azCols[nCol];
+          for(i=0; i<nCol; i++){
+            azVals[i] = (char *)sqlite3_column_text(pStmt, i);
+            if( !azVals[i] && sqlite3_column_type(pStmt, i)!=SQLITE_NULL ){
+              sqlite3OomFault(db);
+              goto exec_out;
+            }
+          }
+        }
+        if( xCallback(pArg, nCol, azVals, azCols) ){
+          /* EVIDENCE-OF: R-38229-40159 If the callback function to
+          ** sqlite3_exec() returns non-zero, then sqlite3_exec() will
+          ** return SQLITE_ABORT. */
+          rc = SQLITE_ABORT;
+          sqlite3VdbeFinalize((Vdbe *)pStmt);
+          pStmt = 0;
+          sqlite3Error(db, SQLITE_ABORT);
+          goto exec_out;
+        }
+      }
+
+      if( rc!=SQLITE_ROW ){
+        rc = sqlite3VdbeFinalize((Vdbe *)pStmt);
+        pStmt = 0;
+        zSql = zLeftover;
+        while( sqlite3Isspace(zSql[0]) ) zSql++;
+        break;
+      }
+    }
+
+    sqlite3DbFree(db, azCols);
+    azCols = 0;
+  }
+
+exec_out:
+  if( pStmt ) sqlite3VdbeFinalize((Vdbe *)pStmt);
+  sqlite3DbFree(db, azCols);
+
+  rc = sqlite3ApiExit(db, rc);
+  if( rc!=SQLITE_OK && pzErrMsg ){
+    int nErrMsg = 1 + sqlite3Strlen30(sqlite3_errmsg(db));
+    *pzErrMsg = sqlite3Malloc(nErrMsg);
+    if( *pzErrMsg ){
+      memcpy(*pzErrMsg, sqlite3_errmsg(db), nErrMsg);
+    }else{
+      rc = SQLITE_NOMEM_BKPT;
+      sqlite3Error(db, SQLITE_NOMEM);
+    }
+  }else if( pzErrMsg ){
+    *pzErrMsg = 0;
+  }
+
+  assert( (rc&db->errMask)==rc );
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+/************** End of legacy.c **********************************************/
+/************** Begin file loadext.c *****************************************/
+/*
+** 2006 June 7
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains code used to dynamically load extensions into
+** the SQLite library.
+*/
+
+#ifndef SQLITE_CORE
+  #define SQLITE_CORE 1  /* Disable the API redefinition in sqlite3ext.h */
+#endif
+/************** Include sqlite3ext.h in the middle of loadext.c **************/
+/************** Begin file sqlite3ext.h **************************************/
+/*
+** 2006 June 7
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This header file defines the SQLite interface for use by
+** shared libraries that want to be imported as extensions into
+** an SQLite instance.  Shared libraries that intend to be loaded
+** as extensions by SQLite should #include this file instead of 
+** sqlite3.h.
+*/
+#ifndef SQLITE3EXT_H
+#define SQLITE3EXT_H
+/* #include "sqlite3.h" */
+
+/*
+** The following structure holds pointers to all of the SQLite API
+** routines.
+**
+** WARNING:  In order to maintain backwards compatibility, add new
+** interfaces to the end of this structure only.  If you insert new
+** interfaces in the middle of this structure, then older different
+** versions of SQLite will not be able to load each other's shared
+** libraries!
+*/
+struct sqlite3_api_routines {
+  void * (*aggregate_context)(sqlite3_context*,int nBytes);
+  int  (*aggregate_count)(sqlite3_context*);
+  int  (*bind_blob)(sqlite3_stmt*,int,const void*,int n,void(*)(void*));
+  int  (*bind_double)(sqlite3_stmt*,int,double);
+  int  (*bind_int)(sqlite3_stmt*,int,int);
+  int  (*bind_int64)(sqlite3_stmt*,int,sqlite_int64);
+  int  (*bind_null)(sqlite3_stmt*,int);
+  int  (*bind_parameter_count)(sqlite3_stmt*);
+  int  (*bind_parameter_index)(sqlite3_stmt*,const char*zName);
+  const char * (*bind_parameter_name)(sqlite3_stmt*,int);
+  int  (*bind_text)(sqlite3_stmt*,int,const char*,int n,void(*)(void*));
+  int  (*bind_text16)(sqlite3_stmt*,int,const void*,int,void(*)(void*));
+  int  (*bind_value)(sqlite3_stmt*,int,const sqlite3_value*);
+  int  (*busy_handler)(sqlite3*,int(*)(void*,int),void*);
+  int  (*busy_timeout)(sqlite3*,int ms);
+  int  (*changes)(sqlite3*);
+  int  (*close)(sqlite3*);
+  int  (*collation_needed)(sqlite3*,void*,void(*)(void*,sqlite3*,
+                           int eTextRep,const char*));
+  int  (*collation_needed16)(sqlite3*,void*,void(*)(void*,sqlite3*,
+                             int eTextRep,const void*));
+  const void * (*column_blob)(sqlite3_stmt*,int iCol);
+  int  (*column_bytes)(sqlite3_stmt*,int iCol);
+  int  (*column_bytes16)(sqlite3_stmt*,int iCol);
+  int  (*column_count)(sqlite3_stmt*pStmt);
+  const char * (*column_database_name)(sqlite3_stmt*,int);
+  const void * (*column_database_name16)(sqlite3_stmt*,int);
+  const char * (*column_decltype)(sqlite3_stmt*,int i);
+  const void * (*column_decltype16)(sqlite3_stmt*,int);
+  double  (*column_double)(sqlite3_stmt*,int iCol);
+  int  (*column_int)(sqlite3_stmt*,int iCol);
+  sqlite_int64  (*column_int64)(sqlite3_stmt*,int iCol);
+  const char * (*column_name)(sqlite3_stmt*,int);
+  const void * (*column_name16)(sqlite3_stmt*,int);
+  const char * (*column_origin_name)(sqlite3_stmt*,int);
+  const void * (*column_origin_name16)(sqlite3_stmt*,int);
+  const char * (*column_table_name)(sqlite3_stmt*,int);
+  const void * (*column_table_name16)(sqlite3_stmt*,int);
+  const unsigned char * (*column_text)(sqlite3_stmt*,int iCol);
+  const void * (*column_text16)(sqlite3_stmt*,int iCol);
+  int  (*column_type)(sqlite3_stmt*,int iCol);
+  sqlite3_value* (*column_value)(sqlite3_stmt*,int iCol);
+  void * (*commit_hook)(sqlite3*,int(*)(void*),void*);
+  int  (*complete)(const char*sql);
+  int  (*complete16)(const void*sql);
+  int  (*create_collation)(sqlite3*,const char*,int,void*,
+                           int(*)(void*,int,const void*,int,const void*));
+  int  (*create_collation16)(sqlite3*,const void*,int,void*,
+                             int(*)(void*,int,const void*,int,const void*));
+  int  (*create_function)(sqlite3*,const char*,int,int,void*,
+                          void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
+                          void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+                          void (*xFinal)(sqlite3_context*));
+  int  (*create_function16)(sqlite3*,const void*,int,int,void*,
+                            void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
+                            void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+                            void (*xFinal)(sqlite3_context*));
+  int (*create_module)(sqlite3*,const char*,const sqlite3_module*,void*);
+  int  (*data_count)(sqlite3_stmt*pStmt);
+  sqlite3 * (*db_handle)(sqlite3_stmt*);
+  int (*declare_vtab)(sqlite3*,const char*);
+  int  (*enable_shared_cache)(int);
+  int  (*errcode)(sqlite3*db);
+  const char * (*errmsg)(sqlite3*);
+  const void * (*errmsg16)(sqlite3*);
+  int  (*exec)(sqlite3*,const char*,sqlite3_callback,void*,char**);
+  int  (*expired)(sqlite3_stmt*);
+  int  (*finalize)(sqlite3_stmt*pStmt);
+  void  (*free)(void*);
+  void  (*free_table)(char**result);
+  int  (*get_autocommit)(sqlite3*);
+  void * (*get_auxdata)(sqlite3_context*,int);
+  int  (*get_table)(sqlite3*,const char*,char***,int*,int*,char**);
+  int  (*global_recover)(void);
+  void  (*interruptx)(sqlite3*);
+  sqlite_int64  (*last_insert_rowid)(sqlite3*);
+  const char * (*libversion)(void);
+  int  (*libversion_number)(void);
+  void *(*malloc)(int);
+  char * (*mprintf)(const char*,...);
+  int  (*open)(const char*,sqlite3**);
+  int  (*open16)(const void*,sqlite3**);
+  int  (*prepare)(sqlite3*,const char*,int,sqlite3_stmt**,const char**);
+  int  (*prepare16)(sqlite3*,const void*,int,sqlite3_stmt**,const void**);
+  void * (*profile)(sqlite3*,void(*)(void*,const char*,sqlite_uint64),void*);
+  void  (*progress_handler)(sqlite3*,int,int(*)(void*),void*);
+  void *(*realloc)(void*,int);
+  int  (*reset)(sqlite3_stmt*pStmt);
+  void  (*result_blob)(sqlite3_context*,const void*,int,void(*)(void*));
+  void  (*result_double)(sqlite3_context*,double);
+  void  (*result_error)(sqlite3_context*,const char*,int);
+  void  (*result_error16)(sqlite3_context*,const void*,int);
+  void  (*result_int)(sqlite3_context*,int);
+  void  (*result_int64)(sqlite3_context*,sqlite_int64);
+  void  (*result_null)(sqlite3_context*);
+  void  (*result_text)(sqlite3_context*,const char*,int,void(*)(void*));
+  void  (*result_text16)(sqlite3_context*,const void*,int,void(*)(void*));
+  void  (*result_text16be)(sqlite3_context*,const void*,int,void(*)(void*));
+  void  (*result_text16le)(sqlite3_context*,const void*,int,void(*)(void*));
+  void  (*result_value)(sqlite3_context*,sqlite3_value*);
+  void * (*rollback_hook)(sqlite3*,void(*)(void*),void*);
+  int  (*set_authorizer)(sqlite3*,int(*)(void*,int,const char*,const char*,
+                         const char*,const char*),void*);
+  void  (*set_auxdata)(sqlite3_context*,int,void*,void (*)(void*));
+  char * (*snprintf)(int,char*,const char*,...);
+  int  (*step)(sqlite3_stmt*);
+  int  (*table_column_metadata)(sqlite3*,const char*,const char*,const char*,
+                                char const**,char const**,int*,int*,int*);
+  void  (*thread_cleanup)(void);
+  int  (*total_changes)(sqlite3*);
+  void * (*trace)(sqlite3*,void(*xTrace)(void*,const char*),void*);
+  int  (*transfer_bindings)(sqlite3_stmt*,sqlite3_stmt*);
+  void * (*update_hook)(sqlite3*,void(*)(void*,int ,char const*,char const*,
+                                         sqlite_int64),void*);
+  void * (*user_data)(sqlite3_context*);
+  const void * (*value_blob)(sqlite3_value*);
+  int  (*value_bytes)(sqlite3_value*);
+  int  (*value_bytes16)(sqlite3_value*);
+  double  (*value_double)(sqlite3_value*);
+  int  (*value_int)(sqlite3_value*);
+  sqlite_int64  (*value_int64)(sqlite3_value*);
+  int  (*value_numeric_type)(sqlite3_value*);
+  const unsigned char * (*value_text)(sqlite3_value*);
+  const void * (*value_text16)(sqlite3_value*);
+  const void * (*value_text16be)(sqlite3_value*);
+  const void * (*value_text16le)(sqlite3_value*);
+  int  (*value_type)(sqlite3_value*);
+  char *(*vmprintf)(const char*,va_list);
+  /* Added ??? */
+  int (*overload_function)(sqlite3*, const char *zFuncName, int nArg);
+  /* Added by 3.3.13 */
+  int (*prepare_v2)(sqlite3*,const char*,int,sqlite3_stmt**,const char**);
+  int (*prepare16_v2)(sqlite3*,const void*,int,sqlite3_stmt**,const void**);
+  int (*clear_bindings)(sqlite3_stmt*);
+  /* Added by 3.4.1 */
+  int (*create_module_v2)(sqlite3*,const char*,const sqlite3_module*,void*,
+                          void (*xDestroy)(void *));
+  /* Added by 3.5.0 */
+  int (*bind_zeroblob)(sqlite3_stmt*,int,int);
+  int (*blob_bytes)(sqlite3_blob*);
+  int (*blob_close)(sqlite3_blob*);
+  int (*blob_open)(sqlite3*,const char*,const char*,const char*,sqlite3_int64,
+                   int,sqlite3_blob**);
+  int (*blob_read)(sqlite3_blob*,void*,int,int);
+  int (*blob_write)(sqlite3_blob*,const void*,int,int);
+  int (*create_collation_v2)(sqlite3*,const char*,int,void*,
+                             int(*)(void*,int,const void*,int,const void*),
+                             void(*)(void*));
+  int (*file_control)(sqlite3*,const char*,int,void*);
+  sqlite3_int64 (*memory_highwater)(int);
+  sqlite3_int64 (*memory_used)(void);
+  sqlite3_mutex *(*mutex_alloc)(int);
+  void (*mutex_enter)(sqlite3_mutex*);
+  void (*mutex_free)(sqlite3_mutex*);
+  void (*mutex_leave)(sqlite3_mutex*);
+  int (*mutex_try)(sqlite3_mutex*);
+  int (*open_v2)(const char*,sqlite3**,int,const char*);
+  int (*release_memory)(int);
+  void (*result_error_nomem)(sqlite3_context*);
+  void (*result_error_toobig)(sqlite3_context*);
+  int (*sleep)(int);
+  void (*soft_heap_limit)(int);
+  sqlite3_vfs *(*vfs_find)(const char*);
+  int (*vfs_register)(sqlite3_vfs*,int);
+  int (*vfs_unregister)(sqlite3_vfs*);
+  int (*xthreadsafe)(void);
+  void (*result_zeroblob)(sqlite3_context*,int);
+  void (*result_error_code)(sqlite3_context*,int);
+  int (*test_control)(int, ...);
+  void (*randomness)(int,void*);
+  sqlite3 *(*context_db_handle)(sqlite3_context*);
+  int (*extended_result_codes)(sqlite3*,int);
+  int (*limit)(sqlite3*,int,int);
+  sqlite3_stmt *(*next_stmt)(sqlite3*,sqlite3_stmt*);
+  const char *(*sql)(sqlite3_stmt*);
+  int (*status)(int,int*,int*,int);
+  int (*backup_finish)(sqlite3_backup*);
+  sqlite3_backup *(*backup_init)(sqlite3*,const char*,sqlite3*,const char*);
+  int (*backup_pagecount)(sqlite3_backup*);
+  int (*backup_remaining)(sqlite3_backup*);
+  int (*backup_step)(sqlite3_backup*,int);
+  const char *(*compileoption_get)(int);
+  int (*compileoption_used)(const char*);
+  int (*create_function_v2)(sqlite3*,const char*,int,int,void*,
+                            void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
+                            void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+                            void (*xFinal)(sqlite3_context*),
+                            void(*xDestroy)(void*));
+  int (*db_config)(sqlite3*,int,...);
+  sqlite3_mutex *(*db_mutex)(sqlite3*);
+  int (*db_status)(sqlite3*,int,int*,int*,int);
+  int (*extended_errcode)(sqlite3*);
+  void (*log)(int,const char*,...);
+  sqlite3_int64 (*soft_heap_limit64)(sqlite3_int64);
+  const char *(*sourceid)(void);
+  int (*stmt_status)(sqlite3_stmt*,int,int);
+  int (*strnicmp)(const char*,const char*,int);
+  int (*unlock_notify)(sqlite3*,void(*)(void**,int),void*);
+  int (*wal_autocheckpoint)(sqlite3*,int);
+  int (*wal_checkpoint)(sqlite3*,const char*);
+  void *(*wal_hook)(sqlite3*,int(*)(void*,sqlite3*,const char*,int),void*);
+  int (*blob_reopen)(sqlite3_blob*,sqlite3_int64);
+  int (*vtab_config)(sqlite3*,int op,...);
+  int (*vtab_on_conflict)(sqlite3*);
+  /* Version 3.7.16 and later */
+  int (*close_v2)(sqlite3*);
+  const char *(*db_filename)(sqlite3*,const char*);
+  int (*db_readonly)(sqlite3*,const char*);
+  int (*db_release_memory)(sqlite3*);
+  const char *(*errstr)(int);
+  int (*stmt_busy)(sqlite3_stmt*);
+  int (*stmt_readonly)(sqlite3_stmt*);
+  int (*stricmp)(const char*,const char*);
+  int (*uri_boolean)(const char*,const char*,int);
+  sqlite3_int64 (*uri_int64)(const char*,const char*,sqlite3_int64);
+  const char *(*uri_parameter)(const char*,const char*);
+  char *(*vsnprintf)(int,char*,const char*,va_list);
+  int (*wal_checkpoint_v2)(sqlite3*,const char*,int,int*,int*);
+  /* Version 3.8.7 and later */
+  int (*auto_extension)(void(*)(void));
+  int (*bind_blob64)(sqlite3_stmt*,int,const void*,sqlite3_uint64,
+                     void(*)(void*));
+  int (*bind_text64)(sqlite3_stmt*,int,const char*,sqlite3_uint64,
+                      void(*)(void*),unsigned char);
+  int (*cancel_auto_extension)(void(*)(void));
+  int (*load_extension)(sqlite3*,const char*,const char*,char**);
+  void *(*malloc64)(sqlite3_uint64);
+  sqlite3_uint64 (*msize)(void*);
+  void *(*realloc64)(void*,sqlite3_uint64);
+  void (*reset_auto_extension)(void);
+  void (*result_blob64)(sqlite3_context*,const void*,sqlite3_uint64,
+                        void(*)(void*));
+  void (*result_text64)(sqlite3_context*,const char*,sqlite3_uint64,
+                         void(*)(void*), unsigned char);
+  int (*strglob)(const char*,const char*);
+  /* Version 3.8.11 and later */
+  sqlite3_value *(*value_dup)(const sqlite3_value*);
+  void (*value_free)(sqlite3_value*);
+  int (*result_zeroblob64)(sqlite3_context*,sqlite3_uint64);
+  int (*bind_zeroblob64)(sqlite3_stmt*, int, sqlite3_uint64);
+  /* Version 3.9.0 and later */
+  unsigned int (*value_subtype)(sqlite3_value*);
+  void (*result_subtype)(sqlite3_context*,unsigned int);
+  /* Version 3.10.0 and later */
+  int (*status64)(int,sqlite3_int64*,sqlite3_int64*,int);
+  int (*strlike)(const char*,const char*,unsigned int);
+  int (*db_cacheflush)(sqlite3*);
+  /* Version 3.12.0 and later */
+  int (*system_errno)(sqlite3*);
+  /* Version 3.14.0 and later */
+  int (*trace_v2)(sqlite3*,unsigned,int(*)(unsigned,void*,void*,void*),void*);
+  char *(*expanded_sql)(sqlite3_stmt*);
+};
+
+/*
+** This is the function signature used for all extension entry points.  It
+** is also defined in the file "loadext.c".
+*/
+typedef int (*sqlite3_loadext_entry)(
+  sqlite3 *db,                       /* Handle to the database. */
+  char **pzErrMsg,                   /* Used to set error string on failure. */
+  const sqlite3_api_routines *pThunk /* Extension API function pointers. */
+);
+
+/*
+** The following macros redefine the API routines so that they are
+** redirected through the global sqlite3_api structure.
+**
+** This header file is also used by the loadext.c source file
+** (part of the main SQLite library - not an extension) so that
+** it can get access to the sqlite3_api_routines structure
+** definition.  But the main library does not want to redefine
+** the API.  So the redefinition macros are only valid if the
+** SQLITE_CORE macros is undefined.
+*/
+#if !defined(SQLITE_CORE) && !defined(SQLITE_OMIT_LOAD_EXTENSION)
+#define sqlite3_aggregate_context      sqlite3_api->aggregate_context
+#ifndef SQLITE_OMIT_DEPRECATED
+#define sqlite3_aggregate_count        sqlite3_api->aggregate_count
+#endif
+#define sqlite3_bind_blob              sqlite3_api->bind_blob
+#define sqlite3_bind_double            sqlite3_api->bind_double
+#define sqlite3_bind_int               sqlite3_api->bind_int
+#define sqlite3_bind_int64             sqlite3_api->bind_int64
+#define sqlite3_bind_null              sqlite3_api->bind_null
+#define sqlite3_bind_parameter_count   sqlite3_api->bind_parameter_count
+#define sqlite3_bind_parameter_index   sqlite3_api->bind_parameter_index
+#define sqlite3_bind_parameter_name    sqlite3_api->bind_parameter_name
+#define sqlite3_bind_text              sqlite3_api->bind_text
+#define sqlite3_bind_text16            sqlite3_api->bind_text16
+#define sqlite3_bind_value             sqlite3_api->bind_value
+#define sqlite3_busy_handler           sqlite3_api->busy_handler
+#define sqlite3_busy_timeout           sqlite3_api->busy_timeout
+#define sqlite3_changes                sqlite3_api->changes
+#define sqlite3_close                  sqlite3_api->close
+#define sqlite3_collation_needed       sqlite3_api->collation_needed
+#define sqlite3_collation_needed16     sqlite3_api->collation_needed16
+#define sqlite3_column_blob            sqlite3_api->column_blob
+#define sqlite3_column_bytes           sqlite3_api->column_bytes
+#define sqlite3_column_bytes16         sqlite3_api->column_bytes16
+#define sqlite3_column_count           sqlite3_api->column_count
+#define sqlite3_column_database_name   sqlite3_api->column_database_name
+#define sqlite3_column_database_name16 sqlite3_api->column_database_name16
+#define sqlite3_column_decltype        sqlite3_api->column_decltype
+#define sqlite3_column_decltype16      sqlite3_api->column_decltype16
+#define sqlite3_column_double          sqlite3_api->column_double
+#define sqlite3_column_int             sqlite3_api->column_int
+#define sqlite3_column_int64           sqlite3_api->column_int64
+#define sqlite3_column_name            sqlite3_api->column_name
+#define sqlite3_column_name16          sqlite3_api->column_name16
+#define sqlite3_column_origin_name     sqlite3_api->column_origin_name
+#define sqlite3_column_origin_name16   sqlite3_api->column_origin_name16
+#define sqlite3_column_table_name      sqlite3_api->column_table_name
+#define sqlite3_column_table_name16    sqlite3_api->column_table_name16
+#define sqlite3_column_text            sqlite3_api->column_text
+#define sqlite3_column_text16          sqlite3_api->column_text16
+#define sqlite3_column_type            sqlite3_api->column_type
+#define sqlite3_column_value           sqlite3_api->column_value
+#define sqlite3_commit_hook            sqlite3_api->commit_hook
+#define sqlite3_complete               sqlite3_api->complete
+#define sqlite3_complete16             sqlite3_api->complete16
+#define sqlite3_create_collation       sqlite3_api->create_collation
+#define sqlite3_create_collation16     sqlite3_api->create_collation16
+#define sqlite3_create_function        sqlite3_api->create_function
+#define sqlite3_create_function16      sqlite3_api->create_function16
+#define sqlite3_create_module          sqlite3_api->create_module
+#define sqlite3_create_module_v2       sqlite3_api->create_module_v2
+#define sqlite3_data_count             sqlite3_api->data_count
+#define sqlite3_db_handle              sqlite3_api->db_handle
+#define sqlite3_declare_vtab           sqlite3_api->declare_vtab
+#define sqlite3_enable_shared_cache    sqlite3_api->enable_shared_cache
+#define sqlite3_errcode                sqlite3_api->errcode
+#define sqlite3_errmsg                 sqlite3_api->errmsg
+#define sqlite3_errmsg16               sqlite3_api->errmsg16
+#define sqlite3_exec                   sqlite3_api->exec
+#ifndef SQLITE_OMIT_DEPRECATED
+#define sqlite3_expired                sqlite3_api->expired
+#endif
+#define sqlite3_finalize               sqlite3_api->finalize
+#define sqlite3_free                   sqlite3_api->free
+#define sqlite3_free_table             sqlite3_api->free_table
+#define sqlite3_get_autocommit         sqlite3_api->get_autocommit
+#define sqlite3_get_auxdata            sqlite3_api->get_auxdata
+#define sqlite3_get_table              sqlite3_api->get_table
+#ifndef SQLITE_OMIT_DEPRECATED
+#define sqlite3_global_recover         sqlite3_api->global_recover
+#endif
+#define sqlite3_interrupt              sqlite3_api->interruptx
+#define sqlite3_last_insert_rowid      sqlite3_api->last_insert_rowid
+#define sqlite3_libversion             sqlite3_api->libversion
+#define sqlite3_libversion_number      sqlite3_api->libversion_number
+#define sqlite3_malloc                 sqlite3_api->malloc
+#define sqlite3_mprintf                sqlite3_api->mprintf
+#define sqlite3_open                   sqlite3_api->open
+#define sqlite3_open16                 sqlite3_api->open16
+#define sqlite3_prepare                sqlite3_api->prepare
+#define sqlite3_prepare16              sqlite3_api->prepare16
+#define sqlite3_prepare_v2             sqlite3_api->prepare_v2
+#define sqlite3_prepare16_v2           sqlite3_api->prepare16_v2
+#define sqlite3_profile                sqlite3_api->profile
+#define sqlite3_progress_handler       sqlite3_api->progress_handler
+#define sqlite3_realloc                sqlite3_api->realloc
+#define sqlite3_reset                  sqlite3_api->reset
+#define sqlite3_result_blob            sqlite3_api->result_blob
+#define sqlite3_result_double          sqlite3_api->result_double
+#define sqlite3_result_error           sqlite3_api->result_error
+#define sqlite3_result_error16         sqlite3_api->result_error16
+#define sqlite3_result_int             sqlite3_api->result_int
+#define sqlite3_result_int64           sqlite3_api->result_int64
+#define sqlite3_result_null            sqlite3_api->result_null
+#define sqlite3_result_text            sqlite3_api->result_text
+#define sqlite3_result_text16          sqlite3_api->result_text16
+#define sqlite3_result_text16be        sqlite3_api->result_text16be
+#define sqlite3_result_text16le        sqlite3_api->result_text16le
+#define sqlite3_result_value           sqlite3_api->result_value
+#define sqlite3_rollback_hook          sqlite3_api->rollback_hook
+#define sqlite3_set_authorizer         sqlite3_api->set_authorizer
+#define sqlite3_set_auxdata            sqlite3_api->set_auxdata
+#define sqlite3_snprintf               sqlite3_api->snprintf
+#define sqlite3_step                   sqlite3_api->step
+#define sqlite3_table_column_metadata  sqlite3_api->table_column_metadata
+#define sqlite3_thread_cleanup         sqlite3_api->thread_cleanup
+#define sqlite3_total_changes          sqlite3_api->total_changes
+#define sqlite3_trace                  sqlite3_api->trace
+#ifndef SQLITE_OMIT_DEPRECATED
+#define sqlite3_transfer_bindings      sqlite3_api->transfer_bindings
+#endif
+#define sqlite3_update_hook            sqlite3_api->update_hook
+#define sqlite3_user_data              sqlite3_api->user_data
+#define sqlite3_value_blob             sqlite3_api->value_blob
+#define sqlite3_value_bytes            sqlite3_api->value_bytes
+#define sqlite3_value_bytes16          sqlite3_api->value_bytes16
+#define sqlite3_value_double           sqlite3_api->value_double
+#define sqlite3_value_int              sqlite3_api->value_int
+#define sqlite3_value_int64            sqlite3_api->value_int64
+#define sqlite3_value_numeric_type     sqlite3_api->value_numeric_type
+#define sqlite3_value_text             sqlite3_api->value_text
+#define sqlite3_value_text16           sqlite3_api->value_text16
+#define sqlite3_value_text16be         sqlite3_api->value_text16be
+#define sqlite3_value_text16le         sqlite3_api->value_text16le
+#define sqlite3_value_type             sqlite3_api->value_type
+#define sqlite3_vmprintf               sqlite3_api->vmprintf
+#define sqlite3_vsnprintf              sqlite3_api->vsnprintf
+#define sqlite3_overload_function      sqlite3_api->overload_function
+#define sqlite3_prepare_v2             sqlite3_api->prepare_v2
+#define sqlite3_prepare16_v2           sqlite3_api->prepare16_v2
+#define sqlite3_clear_bindings         sqlite3_api->clear_bindings
+#define sqlite3_bind_zeroblob          sqlite3_api->bind_zeroblob
+#define sqlite3_blob_bytes             sqlite3_api->blob_bytes
+#define sqlite3_blob_close             sqlite3_api->blob_close
+#define sqlite3_blob_open              sqlite3_api->blob_open
+#define sqlite3_blob_read              sqlite3_api->blob_read
+#define sqlite3_blob_write             sqlite3_api->blob_write
+#define sqlite3_create_collation_v2    sqlite3_api->create_collation_v2
+#define sqlite3_file_control           sqlite3_api->file_control
+#define sqlite3_memory_highwater       sqlite3_api->memory_highwater
+#define sqlite3_memory_used            sqlite3_api->memory_used
+#define sqlite3_mutex_alloc            sqlite3_api->mutex_alloc
+#define sqlite3_mutex_enter            sqlite3_api->mutex_enter
+#define sqlite3_mutex_free             sqlite3_api->mutex_free
+#define sqlite3_mutex_leave            sqlite3_api->mutex_leave
+#define sqlite3_mutex_try              sqlite3_api->mutex_try
+#define sqlite3_open_v2                sqlite3_api->open_v2
+#define sqlite3_release_memory         sqlite3_api->release_memory
+#define sqlite3_result_error_nomem     sqlite3_api->result_error_nomem
+#define sqlite3_result_error_toobig    sqlite3_api->result_error_toobig
+#define sqlite3_sleep                  sqlite3_api->sleep
+#define sqlite3_soft_heap_limit        sqlite3_api->soft_heap_limit
+#define sqlite3_vfs_find               sqlite3_api->vfs_find
+#define sqlite3_vfs_register           sqlite3_api->vfs_register
+#define sqlite3_vfs_unregister         sqlite3_api->vfs_unregister
+#define sqlite3_threadsafe             sqlite3_api->xthreadsafe
+#define sqlite3_result_zeroblob        sqlite3_api->result_zeroblob
+#define sqlite3_result_error_code      sqlite3_api->result_error_code
+#define sqlite3_test_control           sqlite3_api->test_control
+#define sqlite3_randomness             sqlite3_api->randomness
+#define sqlite3_context_db_handle      sqlite3_api->context_db_handle
+#define sqlite3_extended_result_codes  sqlite3_api->extended_result_codes
+#define sqlite3_limit                  sqlite3_api->limit
+#define sqlite3_next_stmt              sqlite3_api->next_stmt
+#define sqlite3_sql                    sqlite3_api->sql
+#define sqlite3_status                 sqlite3_api->status
+#define sqlite3_backup_finish          sqlite3_api->backup_finish
+#define sqlite3_backup_init            sqlite3_api->backup_init
+#define sqlite3_backup_pagecount       sqlite3_api->backup_pagecount
+#define sqlite3_backup_remaining       sqlite3_api->backup_remaining
+#define sqlite3_backup_step            sqlite3_api->backup_step
+#define sqlite3_compileoption_get      sqlite3_api->compileoption_get
+#define sqlite3_compileoption_used     sqlite3_api->compileoption_used
+#define sqlite3_create_function_v2     sqlite3_api->create_function_v2
+#define sqlite3_db_config              sqlite3_api->db_config
+#define sqlite3_db_mutex               sqlite3_api->db_mutex
+#define sqlite3_db_status              sqlite3_api->db_status
+#define sqlite3_extended_errcode       sqlite3_api->extended_errcode
+#define sqlite3_log                    sqlite3_api->log
+#define sqlite3_soft_heap_limit64      sqlite3_api->soft_heap_limit64
+#define sqlite3_sourceid               sqlite3_api->sourceid
+#define sqlite3_stmt_status            sqlite3_api->stmt_status
+#define sqlite3_strnicmp               sqlite3_api->strnicmp
+#define sqlite3_unlock_notify          sqlite3_api->unlock_notify
+#define sqlite3_wal_autocheckpoint     sqlite3_api->wal_autocheckpoint
+#define sqlite3_wal_checkpoint         sqlite3_api->wal_checkpoint
+#define sqlite3_wal_hook               sqlite3_api->wal_hook
+#define sqlite3_blob_reopen            sqlite3_api->blob_reopen
+#define sqlite3_vtab_config            sqlite3_api->vtab_config
+#define sqlite3_vtab_on_conflict       sqlite3_api->vtab_on_conflict
+/* Version 3.7.16 and later */
+#define sqlite3_close_v2               sqlite3_api->close_v2
+#define sqlite3_db_filename            sqlite3_api->db_filename
+#define sqlite3_db_readonly            sqlite3_api->db_readonly
+#define sqlite3_db_release_memory      sqlite3_api->db_release_memory
+#define sqlite3_errstr                 sqlite3_api->errstr
+#define sqlite3_stmt_busy              sqlite3_api->stmt_busy
+#define sqlite3_stmt_readonly          sqlite3_api->stmt_readonly
+#define sqlite3_stricmp                sqlite3_api->stricmp
+#define sqlite3_uri_boolean            sqlite3_api->uri_boolean
+#define sqlite3_uri_int64              sqlite3_api->uri_int64
+#define sqlite3_uri_parameter          sqlite3_api->uri_parameter
+#define sqlite3_uri_vsnprintf          sqlite3_api->vsnprintf
+#define sqlite3_wal_checkpoint_v2      sqlite3_api->wal_checkpoint_v2
+/* Version 3.8.7 and later */
+#define sqlite3_auto_extension         sqlite3_api->auto_extension
+#define sqlite3_bind_blob64            sqlite3_api->bind_blob64
+#define sqlite3_bind_text64            sqlite3_api->bind_text64
+#define sqlite3_cancel_auto_extension  sqlite3_api->cancel_auto_extension
+#define sqlite3_load_extension         sqlite3_api->load_extension
+#define sqlite3_malloc64               sqlite3_api->malloc64
+#define sqlite3_msize                  sqlite3_api->msize
+#define sqlite3_realloc64              sqlite3_api->realloc64
+#define sqlite3_reset_auto_extension   sqlite3_api->reset_auto_extension
+#define sqlite3_result_blob64          sqlite3_api->result_blob64
+#define sqlite3_result_text64          sqlite3_api->result_text64
+#define sqlite3_strglob                sqlite3_api->strglob
+/* Version 3.8.11 and later */
+#define sqlite3_value_dup              sqlite3_api->value_dup
+#define sqlite3_value_free             sqlite3_api->value_free
+#define sqlite3_result_zeroblob64      sqlite3_api->result_zeroblob64
+#define sqlite3_bind_zeroblob64        sqlite3_api->bind_zeroblob64
+/* Version 3.9.0 and later */
+#define sqlite3_value_subtype          sqlite3_api->value_subtype
+#define sqlite3_result_subtype         sqlite3_api->result_subtype
+/* Version 3.10.0 and later */
+#define sqlite3_status64               sqlite3_api->status64
+#define sqlite3_strlike                sqlite3_api->strlike
+#define sqlite3_db_cacheflush          sqlite3_api->db_cacheflush
+/* Version 3.12.0 and later */
+#define sqlite3_system_errno           sqlite3_api->system_errno
+/* Version 3.14.0 and later */
+#define sqlite3_trace_v2               sqlite3_api->trace_v2
+#define sqlite3_expanded_sql           sqlite3_api->expanded_sql
+#endif /* !defined(SQLITE_CORE) && !defined(SQLITE_OMIT_LOAD_EXTENSION) */
+
+#if !defined(SQLITE_CORE) && !defined(SQLITE_OMIT_LOAD_EXTENSION)
+  /* This case when the file really is being compiled as a loadable 
+  ** extension */
+# define SQLITE_EXTENSION_INIT1     const sqlite3_api_routines *sqlite3_api=0;
+# define SQLITE_EXTENSION_INIT2(v)  sqlite3_api=v;
+# define SQLITE_EXTENSION_INIT3     \
+    extern const sqlite3_api_routines *sqlite3_api;
+#else
+  /* This case when the file is being statically linked into the 
+  ** application */
+# define SQLITE_EXTENSION_INIT1     /*no-op*/
+# define SQLITE_EXTENSION_INIT2(v)  (void)v; /* unused parameter */
+# define SQLITE_EXTENSION_INIT3     /*no-op*/
+#endif
+
+#endif /* SQLITE3EXT_H */
+
+/************** End of sqlite3ext.h ******************************************/
+/************** Continuing where we left off in loadext.c ********************/
+/* #include "sqliteInt.h" */
+/* #include <string.h> */
+
+#ifndef SQLITE_OMIT_LOAD_EXTENSION
+/*
+** Some API routines are omitted when various features are
+** excluded from a build of SQLite.  Substitute a NULL pointer
+** for any missing APIs.
+*/
+#ifndef SQLITE_ENABLE_COLUMN_METADATA
+# define sqlite3_column_database_name   0
+# define sqlite3_column_database_name16 0
+# define sqlite3_column_table_name      0
+# define sqlite3_column_table_name16    0
+# define sqlite3_column_origin_name     0
+# define sqlite3_column_origin_name16   0
+#endif
+
+#ifdef SQLITE_OMIT_AUTHORIZATION
+# define sqlite3_set_authorizer         0
+#endif
+
+#ifdef SQLITE_OMIT_UTF16
+# define sqlite3_bind_text16            0
+# define sqlite3_collation_needed16     0
+# define sqlite3_column_decltype16      0
+# define sqlite3_column_name16          0
+# define sqlite3_column_text16          0
+# define sqlite3_complete16             0
+# define sqlite3_create_collation16     0
+# define sqlite3_create_function16      0
+# define sqlite3_errmsg16               0
+# define sqlite3_open16                 0
+# define sqlite3_prepare16              0
+# define sqlite3_prepare16_v2           0
+# define sqlite3_result_error16         0
+# define sqlite3_result_text16          0
+# define sqlite3_result_text16be        0
+# define sqlite3_result_text16le        0
+# define sqlite3_value_text16           0
+# define sqlite3_value_text16be         0
+# define sqlite3_value_text16le         0
+# define sqlite3_column_database_name16 0
+# define sqlite3_column_table_name16    0
+# define sqlite3_column_origin_name16   0
+#endif
+
+#ifdef SQLITE_OMIT_COMPLETE
+# define sqlite3_complete 0
+# define sqlite3_complete16 0
+#endif
+
+#ifdef SQLITE_OMIT_DECLTYPE
+# define sqlite3_column_decltype16      0
+# define sqlite3_column_decltype        0
+#endif
+
+#ifdef SQLITE_OMIT_PROGRESS_CALLBACK
+# define sqlite3_progress_handler 0
+#endif
+
+#ifdef SQLITE_OMIT_VIRTUALTABLE
+# define sqlite3_create_module 0
+# define sqlite3_create_module_v2 0
+# define sqlite3_declare_vtab 0
+# define sqlite3_vtab_config 0
+# define sqlite3_vtab_on_conflict 0
+#endif
+
+#ifdef SQLITE_OMIT_SHARED_CACHE
+# define sqlite3_enable_shared_cache 0
+#endif
+
+#if defined(SQLITE_OMIT_TRACE) || defined(SQLITE_OMIT_DEPRECATED)
+# define sqlite3_profile       0
+# define sqlite3_trace         0
+#endif
+
+#ifdef SQLITE_OMIT_GET_TABLE
+# define sqlite3_free_table    0
+# define sqlite3_get_table     0
+#endif
+
+#ifdef SQLITE_OMIT_INCRBLOB
+#define sqlite3_bind_zeroblob  0
+#define sqlite3_blob_bytes     0
+#define sqlite3_blob_close     0
+#define sqlite3_blob_open      0
+#define sqlite3_blob_read      0
+#define sqlite3_blob_write     0
+#define sqlite3_blob_reopen    0
+#endif
+
+#if defined(SQLITE_OMIT_TRACE)
+# define sqlite3_trace_v2      0
+#endif
+
+/*
+** The following structure contains pointers to all SQLite API routines.
+** A pointer to this structure is passed into extensions when they are
+** loaded so that the extension can make calls back into the SQLite
+** library.
+**
+** When adding new APIs, add them to the bottom of this structure
+** in order to preserve backwards compatibility.
+**
+** Extensions that use newer APIs should first call the
+** sqlite3_libversion_number() to make sure that the API they
+** intend to use is supported by the library.  Extensions should
+** also check to make sure that the pointer to the function is
+** not NULL before calling it.
+*/
+static const sqlite3_api_routines sqlite3Apis = {
+  sqlite3_aggregate_context,
+#ifndef SQLITE_OMIT_DEPRECATED
+  sqlite3_aggregate_count,
+#else
+  0,
+#endif
+  sqlite3_bind_blob,
+  sqlite3_bind_double,
+  sqlite3_bind_int,
+  sqlite3_bind_int64,
+  sqlite3_bind_null,
+  sqlite3_bind_parameter_count,
+  sqlite3_bind_parameter_index,
+  sqlite3_bind_parameter_name,
+  sqlite3_bind_text,
+  sqlite3_bind_text16,
+  sqlite3_bind_value,
+  sqlite3_busy_handler,
+  sqlite3_busy_timeout,
+  sqlite3_changes,
+  sqlite3_close,
+  sqlite3_collation_needed,
+  sqlite3_collation_needed16,
+  sqlite3_column_blob,
+  sqlite3_column_bytes,
+  sqlite3_column_bytes16,
+  sqlite3_column_count,
+  sqlite3_column_database_name,
+  sqlite3_column_database_name16,
+  sqlite3_column_decltype,
+  sqlite3_column_decltype16,
+  sqlite3_column_double,
+  sqlite3_column_int,
+  sqlite3_column_int64,
+  sqlite3_column_name,
+  sqlite3_column_name16,
+  sqlite3_column_origin_name,
+  sqlite3_column_origin_name16,
+  sqlite3_column_table_name,
+  sqlite3_column_table_name16,
+  sqlite3_column_text,
+  sqlite3_column_text16,
+  sqlite3_column_type,
+  sqlite3_column_value,
+  sqlite3_commit_hook,
+  sqlite3_complete,
+  sqlite3_complete16,
+  sqlite3_create_collation,
+  sqlite3_create_collation16,
+  sqlite3_create_function,
+  sqlite3_create_function16,
+  sqlite3_create_module,
+  sqlite3_data_count,
+  sqlite3_db_handle,
+  sqlite3_declare_vtab,
+  sqlite3_enable_shared_cache,
+  sqlite3_errcode,
+  sqlite3_errmsg,
+  sqlite3_errmsg16,
+  sqlite3_exec,
+#ifndef SQLITE_OMIT_DEPRECATED
+  sqlite3_expired,
+#else
+  0,
+#endif
+  sqlite3_finalize,
+  sqlite3_free,
+  sqlite3_free_table,
+  sqlite3_get_autocommit,
+  sqlite3_get_auxdata,
+  sqlite3_get_table,
+  0,     /* Was sqlite3_global_recover(), but that function is deprecated */
+  sqlite3_interrupt,
+  sqlite3_last_insert_rowid,
+  sqlite3_libversion,
+  sqlite3_libversion_number,
+  sqlite3_malloc,
+  sqlite3_mprintf,
+  sqlite3_open,
+  sqlite3_open16,
+  sqlite3_prepare,
+  sqlite3_prepare16,
+  sqlite3_profile,
+  sqlite3_progress_handler,
+  sqlite3_realloc,
+  sqlite3_reset,
+  sqlite3_result_blob,
+  sqlite3_result_double,
+  sqlite3_result_error,
+  sqlite3_result_error16,
+  sqlite3_result_int,
+  sqlite3_result_int64,
+  sqlite3_result_null,
+  sqlite3_result_text,
+  sqlite3_result_text16,
+  sqlite3_result_text16be,
+  sqlite3_result_text16le,
+  sqlite3_result_value,
+  sqlite3_rollback_hook,
+  sqlite3_set_authorizer,
+  sqlite3_set_auxdata,
+  sqlite3_snprintf,
+  sqlite3_step,
+  sqlite3_table_column_metadata,
+#ifndef SQLITE_OMIT_DEPRECATED
+  sqlite3_thread_cleanup,
+#else
+  0,
+#endif
+  sqlite3_total_changes,
+  sqlite3_trace,
+#ifndef SQLITE_OMIT_DEPRECATED
+  sqlite3_transfer_bindings,
+#else
+  0,
+#endif
+  sqlite3_update_hook,
+  sqlite3_user_data,
+  sqlite3_value_blob,
+  sqlite3_value_bytes,
+  sqlite3_value_bytes16,
+  sqlite3_value_double,
+  sqlite3_value_int,
+  sqlite3_value_int64,
+  sqlite3_value_numeric_type,
+  sqlite3_value_text,
+  sqlite3_value_text16,
+  sqlite3_value_text16be,
+  sqlite3_value_text16le,
+  sqlite3_value_type,
+  sqlite3_vmprintf,
+  /*
+  ** The original API set ends here.  All extensions can call any
+  ** of the APIs above provided that the pointer is not NULL.  But
+  ** before calling APIs that follow, extension should check the
+  ** sqlite3_libversion_number() to make sure they are dealing with
+  ** a library that is new enough to support that API.
+  *************************************************************************
+  */
+  sqlite3_overload_function,
+
+  /*
+  ** Added after 3.3.13
+  */
+  sqlite3_prepare_v2,
+  sqlite3_prepare16_v2,
+  sqlite3_clear_bindings,
+
+  /*
+  ** Added for 3.4.1
+  */
+  sqlite3_create_module_v2,
+
+  /*
+  ** Added for 3.5.0
+  */
+  sqlite3_bind_zeroblob,
+  sqlite3_blob_bytes,
+  sqlite3_blob_close,
+  sqlite3_blob_open,
+  sqlite3_blob_read,
+  sqlite3_blob_write,
+  sqlite3_create_collation_v2,
+  sqlite3_file_control,
+  sqlite3_memory_highwater,
+  sqlite3_memory_used,
+#ifdef SQLITE_MUTEX_OMIT
+  0, 
+  0, 
+  0,
+  0,
+  0,
+#else
+  sqlite3_mutex_alloc,
+  sqlite3_mutex_enter,
+  sqlite3_mutex_free,
+  sqlite3_mutex_leave,
+  sqlite3_mutex_try,
+#endif
+  sqlite3_open_v2,
+  sqlite3_release_memory,
+  sqlite3_result_error_nomem,
+  sqlite3_result_error_toobig,
+  sqlite3_sleep,
+  sqlite3_soft_heap_limit,
+  sqlite3_vfs_find,
+  sqlite3_vfs_register,
+  sqlite3_vfs_unregister,
+
+  /*
+  ** Added for 3.5.8
+  */
+  sqlite3_threadsafe,
+  sqlite3_result_zeroblob,
+  sqlite3_result_error_code,
+  sqlite3_test_control,
+  sqlite3_randomness,
+  sqlite3_context_db_handle,
+
+  /*
+  ** Added for 3.6.0
+  */
+  sqlite3_extended_result_codes,
+  sqlite3_limit,
+  sqlite3_next_stmt,
+  sqlite3_sql,
+  sqlite3_status,
+
+  /*
+  ** Added for 3.7.4
+  */
+  sqlite3_backup_finish,
+  sqlite3_backup_init,
+  sqlite3_backup_pagecount,
+  sqlite3_backup_remaining,
+  sqlite3_backup_step,
+#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
+  sqlite3_compileoption_get,
+  sqlite3_compileoption_used,
+#else
+  0,
+  0,
+#endif
+  sqlite3_create_function_v2,
+  sqlite3_db_config,
+  sqlite3_db_mutex,
+  sqlite3_db_status,
+  sqlite3_extended_errcode,
+  sqlite3_log,
+  sqlite3_soft_heap_limit64,
+  sqlite3_sourceid,
+  sqlite3_stmt_status,
+  sqlite3_strnicmp,
+#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
+  sqlite3_unlock_notify,
+#else
+  0,
+#endif
+#ifndef SQLITE_OMIT_WAL
+  sqlite3_wal_autocheckpoint,
+  sqlite3_wal_checkpoint,
+  sqlite3_wal_hook,
+#else
+  0,
+  0,
+  0,
+#endif
+  sqlite3_blob_reopen,
+  sqlite3_vtab_config,
+  sqlite3_vtab_on_conflict,
+  sqlite3_close_v2,
+  sqlite3_db_filename,
+  sqlite3_db_readonly,
+  sqlite3_db_release_memory,
+  sqlite3_errstr,
+  sqlite3_stmt_busy,
+  sqlite3_stmt_readonly,
+  sqlite3_stricmp,
+  sqlite3_uri_boolean,
+  sqlite3_uri_int64,
+  sqlite3_uri_parameter,
+  sqlite3_vsnprintf,
+  sqlite3_wal_checkpoint_v2,
+  /* Version 3.8.7 and later */
+  sqlite3_auto_extension,
+  sqlite3_bind_blob64,
+  sqlite3_bind_text64,
+  sqlite3_cancel_auto_extension,
+  sqlite3_load_extension,
+  sqlite3_malloc64,
+  sqlite3_msize,
+  sqlite3_realloc64,
+  sqlite3_reset_auto_extension,
+  sqlite3_result_blob64,
+  sqlite3_result_text64,
+  sqlite3_strglob,
+  /* Version 3.8.11 and later */
+  (sqlite3_value*(*)(const sqlite3_value*))sqlite3_value_dup,
+  sqlite3_value_free,
+  sqlite3_result_zeroblob64,
+  sqlite3_bind_zeroblob64,
+  /* Version 3.9.0 and later */
+  sqlite3_value_subtype,
+  sqlite3_result_subtype,
+  /* Version 3.10.0 and later */
+  sqlite3_status64,
+  sqlite3_strlike,
+  sqlite3_db_cacheflush,
+  /* Version 3.12.0 and later */
+  sqlite3_system_errno,
+  /* Version 3.14.0 and later */
+  sqlite3_trace_v2,
+  sqlite3_expanded_sql
+};
+
+/*
+** Attempt to load an SQLite extension library contained in the file
+** zFile.  The entry point is zProc.  zProc may be 0 in which case a
+** default entry point name (sqlite3_extension_init) is used.  Use
+** of the default name is recommended.
+**
+** Return SQLITE_OK on success and SQLITE_ERROR if something goes wrong.
+**
+** If an error occurs and pzErrMsg is not 0, then fill *pzErrMsg with 
+** error message text.  The calling function should free this memory
+** by calling sqlite3DbFree(db, ).
+*/
+static int sqlite3LoadExtension(
+  sqlite3 *db,          /* Load the extension into this database connection */
+  const char *zFile,    /* Name of the shared library containing extension */
+  const char *zProc,    /* Entry point.  Use "sqlite3_extension_init" if 0 */
+  char **pzErrMsg       /* Put error message here if not 0 */
+){
+  sqlite3_vfs *pVfs = db->pVfs;
+  void *handle;
+  sqlite3_loadext_entry xInit;
+  char *zErrmsg = 0;
+  const char *zEntry;
+  char *zAltEntry = 0;
+  void **aHandle;
+  u64 nMsg = 300 + sqlite3Strlen30(zFile);
+  int ii;
+  int rc;
+
+  /* Shared library endings to try if zFile cannot be loaded as written */
+  static const char *azEndings[] = {
+#if SQLITE_OS_WIN
+     "dll"   
+#elif defined(__APPLE__)
+     "dylib"
+#else
+     "so"
+#endif
+  };
+
+
+  if( pzErrMsg ) *pzErrMsg = 0;
+
+  /* Ticket #1863.  To avoid a creating security problems for older
+  ** applications that relink against newer versions of SQLite, the
+  ** ability to run load_extension is turned off by default.  One
+  ** must call either sqlite3_enable_load_extension(db) or
+  ** sqlite3_db_config(db, SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION, 1, 0)
+  ** to turn on extension loading.
+  */
+  if( (db->flags & SQLITE_LoadExtension)==0 ){
+    if( pzErrMsg ){
+      *pzErrMsg = sqlite3_mprintf("not authorized");
+    }
+    return SQLITE_ERROR;
+  }
+
+  zEntry = zProc ? zProc : "sqlite3_extension_init";
+
+  handle = sqlite3OsDlOpen(pVfs, zFile);
+#if SQLITE_OS_UNIX || SQLITE_OS_WIN
+  for(ii=0; ii<ArraySize(azEndings) && handle==0; ii++){
+    char *zAltFile = sqlite3_mprintf("%s.%s", zFile, azEndings[ii]);
+    if( zAltFile==0 ) return SQLITE_NOMEM_BKPT;
+    handle = sqlite3OsDlOpen(pVfs, zAltFile);
+    sqlite3_free(zAltFile);
+  }
+#endif
+  if( handle==0 ){
+    if( pzErrMsg ){
+      *pzErrMsg = zErrmsg = sqlite3_malloc64(nMsg);
+      if( zErrmsg ){
+        sqlite3_snprintf(nMsg, zErrmsg, 
+            "unable to open shared library [%s]", zFile);
+        sqlite3OsDlError(pVfs, nMsg-1, zErrmsg);
+      }
+    }
+    return SQLITE_ERROR;
+  }
+  xInit = (sqlite3_loadext_entry)sqlite3OsDlSym(pVfs, handle, zEntry);
+
+  /* If no entry point was specified and the default legacy
+  ** entry point name "sqlite3_extension_init" was not found, then
+  ** construct an entry point name "sqlite3_X_init" where the X is
+  ** replaced by the lowercase value of every ASCII alphabetic 
+  ** character in the filename after the last "/" upto the first ".",
+  ** and eliding the first three characters if they are "lib".  
+  ** Examples:
+  **
+  **    /usr/local/lib/libExample5.4.3.so ==>  sqlite3_example_init
+  **    C:/lib/mathfuncs.dll              ==>  sqlite3_mathfuncs_init
+  */
+  if( xInit==0 && zProc==0 ){
+    int iFile, iEntry, c;
+    int ncFile = sqlite3Strlen30(zFile);
+    zAltEntry = sqlite3_malloc64(ncFile+30);
+    if( zAltEntry==0 ){
+      sqlite3OsDlClose(pVfs, handle);
+      return SQLITE_NOMEM_BKPT;
+    }
+    memcpy(zAltEntry, "sqlite3_", 8);
+    for(iFile=ncFile-1; iFile>=0 && zFile[iFile]!='/'; iFile--){}
+    iFile++;
+    if( sqlite3_strnicmp(zFile+iFile, "lib", 3)==0 ) iFile += 3;
+    for(iEntry=8; (c = zFile[iFile])!=0 && c!='.'; iFile++){
+      if( sqlite3Isalpha(c) ){
+        zAltEntry[iEntry++] = (char)sqlite3UpperToLower[(unsigned)c];
+      }
+    }
+    memcpy(zAltEntry+iEntry, "_init", 6);
+    zEntry = zAltEntry;
+    xInit = (sqlite3_loadext_entry)sqlite3OsDlSym(pVfs, handle, zEntry);
+  }
+  if( xInit==0 ){
+    if( pzErrMsg ){
+      nMsg += sqlite3Strlen30(zEntry);
+      *pzErrMsg = zErrmsg = sqlite3_malloc64(nMsg);
+      if( zErrmsg ){
+        sqlite3_snprintf(nMsg, zErrmsg,
+            "no entry point [%s] in shared library [%s]", zEntry, zFile);
+        sqlite3OsDlError(pVfs, nMsg-1, zErrmsg);
+      }
+    }
+    sqlite3OsDlClose(pVfs, handle);
+    sqlite3_free(zAltEntry);
+    return SQLITE_ERROR;
+  }
+  sqlite3_free(zAltEntry);
+  rc = xInit(db, &zErrmsg, &sqlite3Apis);
+  if( rc ){
+    if( rc==SQLITE_OK_LOAD_PERMANENTLY ) return SQLITE_OK;
+    if( pzErrMsg ){
+      *pzErrMsg = sqlite3_mprintf("error during initialization: %s", zErrmsg);
+    }
+    sqlite3_free(zErrmsg);
+    sqlite3OsDlClose(pVfs, handle);
+    return SQLITE_ERROR;
+  }
+
+  /* Append the new shared library handle to the db->aExtension array. */
+  aHandle = sqlite3DbMallocZero(db, sizeof(handle)*(db->nExtension+1));
+  if( aHandle==0 ){
+    return SQLITE_NOMEM_BKPT;
+  }
+  if( db->nExtension>0 ){
+    memcpy(aHandle, db->aExtension, sizeof(handle)*db->nExtension);
+  }
+  sqlite3DbFree(db, db->aExtension);
+  db->aExtension = aHandle;
+
+  db->aExtension[db->nExtension++] = handle;
+  return SQLITE_OK;
+}
+SQLITE_API int sqlite3_load_extension(
+  sqlite3 *db,          /* Load the extension into this database connection */
+  const char *zFile,    /* Name of the shared library containing extension */
+  const char *zProc,    /* Entry point.  Use "sqlite3_extension_init" if 0 */
+  char **pzErrMsg       /* Put error message here if not 0 */
+){
+  int rc;
+  sqlite3_mutex_enter(db->mutex);
+  rc = sqlite3LoadExtension(db, zFile, zProc, pzErrMsg);
+  rc = sqlite3ApiExit(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+/*
+** Call this routine when the database connection is closing in order
+** to clean up loaded extensions
+*/
+SQLITE_PRIVATE void sqlite3CloseExtensions(sqlite3 *db){
+  int i;
+  assert( sqlite3_mutex_held(db->mutex) );
+  for(i=0; i<db->nExtension; i++){
+    sqlite3OsDlClose(db->pVfs, db->aExtension[i]);
+  }
+  sqlite3DbFree(db, db->aExtension);
+}
+
+/*
+** Enable or disable extension loading.  Extension loading is disabled by
+** default so as not to open security holes in older applications.
+*/
+SQLITE_API int sqlite3_enable_load_extension(sqlite3 *db, int onoff){
+  sqlite3_mutex_enter(db->mutex);
+  if( onoff ){
+    db->flags |= SQLITE_LoadExtension|SQLITE_LoadExtFunc;
+  }else{
+    db->flags &= ~(SQLITE_LoadExtension|SQLITE_LoadExtFunc);
+  }
+  sqlite3_mutex_leave(db->mutex);
+  return SQLITE_OK;
+}
+
+#endif /* !defined(SQLITE_OMIT_LOAD_EXTENSION) */
+
+/*
+** The following object holds the list of automatically loaded
+** extensions.
+**
+** This list is shared across threads.  The SQLITE_MUTEX_STATIC_MASTER
+** mutex must be held while accessing this list.
+*/
+typedef struct sqlite3AutoExtList sqlite3AutoExtList;
+static SQLITE_WSD struct sqlite3AutoExtList {
+  u32 nExt;              /* Number of entries in aExt[] */          
+  void (**aExt)(void);   /* Pointers to the extension init functions */
+} sqlite3Autoext = { 0, 0 };
+
+/* The "wsdAutoext" macro will resolve to the autoextension
+** state vector.  If writable static data is unsupported on the target,
+** we have to locate the state vector at run-time.  In the more common
+** case where writable static data is supported, wsdStat can refer directly
+** to the "sqlite3Autoext" state vector declared above.
+*/
+#ifdef SQLITE_OMIT_WSD
+# define wsdAutoextInit \
+  sqlite3AutoExtList *x = &GLOBAL(sqlite3AutoExtList,sqlite3Autoext)
+# define wsdAutoext x[0]
+#else
+# define wsdAutoextInit
+# define wsdAutoext sqlite3Autoext
+#endif
+
+
+/*
+** Register a statically linked extension that is automatically
+** loaded by every new database connection.
+*/
+SQLITE_API int sqlite3_auto_extension(
+  void (*xInit)(void)
+){
+  int rc = SQLITE_OK;
+#ifndef SQLITE_OMIT_AUTOINIT
+  rc = sqlite3_initialize();
+  if( rc ){
+    return rc;
+  }else
+#endif
+  {
+    u32 i;
+#if SQLITE_THREADSAFE
+    sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
+#endif
+    wsdAutoextInit;
+    sqlite3_mutex_enter(mutex);
+    for(i=0; i<wsdAutoext.nExt; i++){
+      if( wsdAutoext.aExt[i]==xInit ) break;
+    }
+    if( i==wsdAutoext.nExt ){
+      u64 nByte = (wsdAutoext.nExt+1)*sizeof(wsdAutoext.aExt[0]);
+      void (**aNew)(void);
+      aNew = sqlite3_realloc64(wsdAutoext.aExt, nByte);
+      if( aNew==0 ){
+        rc = SQLITE_NOMEM_BKPT;
+      }else{
+        wsdAutoext.aExt = aNew;
+        wsdAutoext.aExt[wsdAutoext.nExt] = xInit;
+        wsdAutoext.nExt++;
+      }
+    }
+    sqlite3_mutex_leave(mutex);
+    assert( (rc&0xff)==rc );
+    return rc;
+  }
+}
+
+/*
+** Cancel a prior call to sqlite3_auto_extension.  Remove xInit from the
+** set of routines that is invoked for each new database connection, if it
+** is currently on the list.  If xInit is not on the list, then this
+** routine is a no-op.
+**
+** Return 1 if xInit was found on the list and removed.  Return 0 if xInit
+** was not on the list.
+*/
+SQLITE_API int sqlite3_cancel_auto_extension(
+  void (*xInit)(void)
+){
+#if SQLITE_THREADSAFE
+  sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
+#endif
+  int i;
+  int n = 0;
+  wsdAutoextInit;
+  sqlite3_mutex_enter(mutex);
+  for(i=(int)wsdAutoext.nExt-1; i>=0; i--){
+    if( wsdAutoext.aExt[i]==xInit ){
+      wsdAutoext.nExt--;
+      wsdAutoext.aExt[i] = wsdAutoext.aExt[wsdAutoext.nExt];
+      n++;
+      break;
+    }
+  }
+  sqlite3_mutex_leave(mutex);
+  return n;
+}
+
+/*
+** Reset the automatic extension loading mechanism.
+*/
+SQLITE_API void sqlite3_reset_auto_extension(void){
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize()==SQLITE_OK )
+#endif
+  {
+#if SQLITE_THREADSAFE
+    sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
+#endif
+    wsdAutoextInit;
+    sqlite3_mutex_enter(mutex);
+    sqlite3_free(wsdAutoext.aExt);
+    wsdAutoext.aExt = 0;
+    wsdAutoext.nExt = 0;
+    sqlite3_mutex_leave(mutex);
+  }
+}
+
+/*
+** Load all automatic extensions.
+**
+** If anything goes wrong, set an error in the database connection.
+*/
+SQLITE_PRIVATE void sqlite3AutoLoadExtensions(sqlite3 *db){
+  u32 i;
+  int go = 1;
+  int rc;
+  sqlite3_loadext_entry xInit;
+
+  wsdAutoextInit;
+  if( wsdAutoext.nExt==0 ){
+    /* Common case: early out without every having to acquire a mutex */
+    return;
+  }
+  for(i=0; go; i++){
+    char *zErrmsg;
+#if SQLITE_THREADSAFE
+    sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
+#endif
+#ifdef SQLITE_OMIT_LOAD_EXTENSION
+    const sqlite3_api_routines *pThunk = 0;
+#else
+    const sqlite3_api_routines *pThunk = &sqlite3Apis;
+#endif
+    sqlite3_mutex_enter(mutex);
+    if( i>=wsdAutoext.nExt ){
+      xInit = 0;
+      go = 0;
+    }else{
+      xInit = (sqlite3_loadext_entry)wsdAutoext.aExt[i];
+    }
+    sqlite3_mutex_leave(mutex);
+    zErrmsg = 0;
+    if( xInit && (rc = xInit(db, &zErrmsg, pThunk))!=0 ){
+      sqlite3ErrorWithMsg(db, rc,
+            "automatic extension loading failed: %s", zErrmsg);
+      go = 0;
+    }
+    sqlite3_free(zErrmsg);
+  }
+}
+
+/************** End of loadext.c *********************************************/
+/************** Begin file pragma.c ******************************************/
+/*
+** 2003 April 6
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains code used to implement the PRAGMA command.
+*/
+/* #include "sqliteInt.h" */
+
+#if !defined(SQLITE_ENABLE_LOCKING_STYLE)
+#  if defined(__APPLE__)
+#    define SQLITE_ENABLE_LOCKING_STYLE 1
+#  else
+#    define SQLITE_ENABLE_LOCKING_STYLE 0
+#  endif
+#endif
+
+/***************************************************************************
+** The "pragma.h" include file is an automatically generated file that
+** that includes the PragType_XXXX macro definitions and the aPragmaName[]
+** object.  This ensures that the aPragmaName[] table is arranged in
+** lexicographical order to facility a binary search of the pragma name.
+** Do not edit pragma.h directly.  Edit and rerun the script in at 
+** ../tool/mkpragmatab.tcl. */
+/************** Include pragma.h in the middle of pragma.c *******************/
+/************** Begin file pragma.h ******************************************/
+/* DO NOT EDIT!
+** This file is automatically generated by the script at
+** ../tool/mkpragmatab.tcl.  To update the set of pragmas, edit
+** that script and rerun it.
+*/
+#define PragTyp_HEADER_VALUE                   0
+#define PragTyp_AUTO_VACUUM                    1
+#define PragTyp_FLAG                           2
+#define PragTyp_BUSY_TIMEOUT                   3
+#define PragTyp_CACHE_SIZE                     4
+#define PragTyp_CACHE_SPILL                    5
+#define PragTyp_CASE_SENSITIVE_LIKE            6
+#define PragTyp_COLLATION_LIST                 7
+#define PragTyp_COMPILE_OPTIONS                8
+#define PragTyp_DATA_STORE_DIRECTORY           9
+#define PragTyp_DATABASE_LIST                 10
+#define PragTyp_DEFAULT_CACHE_SIZE            11
+#define PragTyp_ENCODING                      12
+#define PragTyp_FOREIGN_KEY_CHECK             13
+#define PragTyp_FOREIGN_KEY_LIST              14
+#define PragTyp_INCREMENTAL_VACUUM            15
+#define PragTyp_INDEX_INFO                    16
+#define PragTyp_INDEX_LIST                    17
+#define PragTyp_INTEGRITY_CHECK               18
+#define PragTyp_JOURNAL_MODE                  19
+#define PragTyp_JOURNAL_SIZE_LIMIT            20
+#define PragTyp_LOCK_PROXY_FILE               21
+#define PragTyp_LOCKING_MODE                  22
+#define PragTyp_PAGE_COUNT                    23
+#define PragTyp_MMAP_SIZE                     24
+#define PragTyp_PAGE_SIZE                     25
+#define PragTyp_SECURE_DELETE                 26
+#define PragTyp_SHRINK_MEMORY                 27
+#define PragTyp_SOFT_HEAP_LIMIT               28
+#define PragTyp_STATS                         29
+#define PragTyp_SYNCHRONOUS                   30
+#define PragTyp_TABLE_INFO                    31
+#define PragTyp_TEMP_STORE                    32
+#define PragTyp_TEMP_STORE_DIRECTORY          33
+#define PragTyp_THREADS                       34
+#define PragTyp_WAL_AUTOCHECKPOINT            35
+#define PragTyp_WAL_CHECKPOINT                36
+#define PragTyp_ACTIVATE_EXTENSIONS           37
+#define PragTyp_HEXKEY                        38
+#define PragTyp_KEY                           39
+#define PragTyp_REKEY                         40
+#define PragTyp_LOCK_STATUS                   41
+#define PragTyp_PARSER_TRACE                  42
+#define PragFlag_NeedSchema           0x01
+#define PragFlag_ReadOnly             0x02
+static const struct sPragmaNames {
+  const char *const zName;  /* Name of pragma */
+  u8 ePragTyp;              /* PragTyp_XXX value */
+  u8 mPragFlag;             /* Zero or more PragFlag_XXX values */
+  u32 iArg;                 /* Extra argument */
+} aPragmaNames[] = {
+#if defined(SQLITE_HAS_CODEC) || defined(SQLITE_ENABLE_CEROD)
+  { /* zName:     */ "activate_extensions",
+    /* ePragTyp:  */ PragTyp_ACTIVATE_EXTENSIONS,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS)
+  { /* zName:     */ "application_id",
+    /* ePragTyp:  */ PragTyp_HEADER_VALUE,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ BTREE_APPLICATION_ID },
+#endif
+#if !defined(SQLITE_OMIT_AUTOVACUUM)
+  { /* zName:     */ "auto_vacuum",
+    /* ePragTyp:  */ PragTyp_AUTO_VACUUM,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+#if !defined(SQLITE_OMIT_AUTOMATIC_INDEX)
+  { /* zName:     */ "automatic_index",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_AutoIndex },
+#endif
+#endif
+  { /* zName:     */ "busy_timeout",
+    /* ePragTyp:  */ PragTyp_BUSY_TIMEOUT,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#if !defined(SQLITE_OMIT_PAGER_PRAGMAS)
+  { /* zName:     */ "cache_size",
+    /* ePragTyp:  */ PragTyp_CACHE_SIZE,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+  { /* zName:     */ "cache_spill",
+    /* ePragTyp:  */ PragTyp_CACHE_SPILL,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#endif
+  { /* zName:     */ "case_sensitive_like",
+    /* ePragTyp:  */ PragTyp_CASE_SENSITIVE_LIKE,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+  { /* zName:     */ "cell_size_check",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_CellSizeCk },
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+  { /* zName:     */ "checkpoint_fullfsync",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_CkptFullFSync },
+#endif
+#if !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)
+  { /* zName:     */ "collation_list",
+    /* ePragTyp:  */ PragTyp_COLLATION_LIST,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_COMPILEOPTION_DIAGS)
+  { /* zName:     */ "compile_options",
+    /* ePragTyp:  */ PragTyp_COMPILE_OPTIONS,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+  { /* zName:     */ "count_changes",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_CountRows },
+#endif
+#if !defined(SQLITE_OMIT_PAGER_PRAGMAS) && SQLITE_OS_WIN
+  { /* zName:     */ "data_store_directory",
+    /* ePragTyp:  */ PragTyp_DATA_STORE_DIRECTORY,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS)
+  { /* zName:     */ "data_version",
+    /* ePragTyp:  */ PragTyp_HEADER_VALUE,
+    /* ePragFlag: */ PragFlag_ReadOnly,
+    /* iArg:      */ BTREE_DATA_VERSION },
+#endif
+#if !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)
+  { /* zName:     */ "database_list",
+    /* ePragTyp:  */ PragTyp_DATABASE_LIST,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_PAGER_PRAGMAS) && !defined(SQLITE_OMIT_DEPRECATED)
+  { /* zName:     */ "default_cache_size",
+    /* ePragTyp:  */ PragTyp_DEFAULT_CACHE_SIZE,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+#if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
+  { /* zName:     */ "defer_foreign_keys",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_DeferFKs },
+#endif
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+  { /* zName:     */ "empty_result_callbacks",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_NullCallback },
+#endif
+#if !defined(SQLITE_OMIT_UTF16)
+  { /* zName:     */ "encoding",
+    /* ePragTyp:  */ PragTyp_ENCODING,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
+  { /* zName:     */ "foreign_key_check",
+    /* ePragTyp:  */ PragTyp_FOREIGN_KEY_CHECK,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_FOREIGN_KEY)
+  { /* zName:     */ "foreign_key_list",
+    /* ePragTyp:  */ PragTyp_FOREIGN_KEY_LIST,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+#if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
+  { /* zName:     */ "foreign_keys",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_ForeignKeys },
+#endif
+#endif
+#if !defined(SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS)
+  { /* zName:     */ "freelist_count",
+    /* ePragTyp:  */ PragTyp_HEADER_VALUE,
+    /* ePragFlag: */ PragFlag_ReadOnly,
+    /* iArg:      */ BTREE_FREE_PAGE_COUNT },
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+  { /* zName:     */ "full_column_names",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_FullColNames },
+  { /* zName:     */ "fullfsync",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_FullFSync },
+#endif
+#if defined(SQLITE_HAS_CODEC)
+  { /* zName:     */ "hexkey",
+    /* ePragTyp:  */ PragTyp_HEXKEY,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+  { /* zName:     */ "hexrekey",
+    /* ePragTyp:  */ PragTyp_HEXKEY,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+#if !defined(SQLITE_OMIT_CHECK)
+  { /* zName:     */ "ignore_check_constraints",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_IgnoreChecks },
+#endif
+#endif
+#if !defined(SQLITE_OMIT_AUTOVACUUM)
+  { /* zName:     */ "incremental_vacuum",
+    /* ePragTyp:  */ PragTyp_INCREMENTAL_VACUUM,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)
+  { /* zName:     */ "index_info",
+    /* ePragTyp:  */ PragTyp_INDEX_INFO,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+  { /* zName:     */ "index_list",
+    /* ePragTyp:  */ PragTyp_INDEX_LIST,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+  { /* zName:     */ "index_xinfo",
+    /* ePragTyp:  */ PragTyp_INDEX_INFO,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 1 },
+#endif
+#if !defined(SQLITE_OMIT_INTEGRITY_CHECK)
+  { /* zName:     */ "integrity_check",
+    /* ePragTyp:  */ PragTyp_INTEGRITY_CHECK,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_PAGER_PRAGMAS)
+  { /* zName:     */ "journal_mode",
+    /* ePragTyp:  */ PragTyp_JOURNAL_MODE,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+  { /* zName:     */ "journal_size_limit",
+    /* ePragTyp:  */ PragTyp_JOURNAL_SIZE_LIMIT,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#endif
+#if defined(SQLITE_HAS_CODEC)
+  { /* zName:     */ "key",
+    /* ePragTyp:  */ PragTyp_KEY,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+  { /* zName:     */ "legacy_file_format",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_LegacyFileFmt },
+#endif
+#if !defined(SQLITE_OMIT_PAGER_PRAGMAS) && SQLITE_ENABLE_LOCKING_STYLE
+  { /* zName:     */ "lock_proxy_file",
+    /* ePragTyp:  */ PragTyp_LOCK_PROXY_FILE,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#endif
+#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
+  { /* zName:     */ "lock_status",
+    /* ePragTyp:  */ PragTyp_LOCK_STATUS,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_PAGER_PRAGMAS)
+  { /* zName:     */ "locking_mode",
+    /* ePragTyp:  */ PragTyp_LOCKING_MODE,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+  { /* zName:     */ "max_page_count",
+    /* ePragTyp:  */ PragTyp_PAGE_COUNT,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+  { /* zName:     */ "mmap_size",
+    /* ePragTyp:  */ PragTyp_MMAP_SIZE,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+  { /* zName:     */ "page_count",
+    /* ePragTyp:  */ PragTyp_PAGE_COUNT,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+  { /* zName:     */ "page_size",
+    /* ePragTyp:  */ PragTyp_PAGE_SIZE,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#endif
+#if defined(SQLITE_DEBUG) && !defined(SQLITE_OMIT_PARSER_TRACE)
+  { /* zName:     */ "parser_trace",
+    /* ePragTyp:  */ PragTyp_PARSER_TRACE,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+  { /* zName:     */ "query_only",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_QueryOnly },
+#endif
+#if !defined(SQLITE_OMIT_INTEGRITY_CHECK)
+  { /* zName:     */ "quick_check",
+    /* ePragTyp:  */ PragTyp_INTEGRITY_CHECK,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+  { /* zName:     */ "read_uncommitted",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_ReadUncommitted },
+  { /* zName:     */ "recursive_triggers",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_RecTriggers },
+#endif
+#if defined(SQLITE_HAS_CODEC)
+  { /* zName:     */ "rekey",
+    /* ePragTyp:  */ PragTyp_REKEY,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+  { /* zName:     */ "reverse_unordered_selects",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_ReverseOrder },
+#endif
+#if !defined(SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS)
+  { /* zName:     */ "schema_version",
+    /* ePragTyp:  */ PragTyp_HEADER_VALUE,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ BTREE_SCHEMA_VERSION },
+#endif
+#if !defined(SQLITE_OMIT_PAGER_PRAGMAS)
+  { /* zName:     */ "secure_delete",
+    /* ePragTyp:  */ PragTyp_SECURE_DELETE,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+  { /* zName:     */ "short_column_names",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_ShortColNames },
+#endif
+  { /* zName:     */ "shrink_memory",
+    /* ePragTyp:  */ PragTyp_SHRINK_MEMORY,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+  { /* zName:     */ "soft_heap_limit",
+    /* ePragTyp:  */ PragTyp_SOFT_HEAP_LIMIT,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+#if defined(SQLITE_DEBUG)
+  { /* zName:     */ "sql_trace",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_SqlTrace },
+#endif
+#endif
+#if !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)
+  { /* zName:     */ "stats",
+    /* ePragTyp:  */ PragTyp_STATS,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_PAGER_PRAGMAS)
+  { /* zName:     */ "synchronous",
+    /* ePragTyp:  */ PragTyp_SYNCHRONOUS,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)
+  { /* zName:     */ "table_info",
+    /* ePragTyp:  */ PragTyp_TABLE_INFO,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_PAGER_PRAGMAS)
+  { /* zName:     */ "temp_store",
+    /* ePragTyp:  */ PragTyp_TEMP_STORE,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+  { /* zName:     */ "temp_store_directory",
+    /* ePragTyp:  */ PragTyp_TEMP_STORE_DIRECTORY,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#endif
+  { /* zName:     */ "threads",
+    /* ePragTyp:  */ PragTyp_THREADS,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+#if !defined(SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS)
+  { /* zName:     */ "user_version",
+    /* ePragTyp:  */ PragTyp_HEADER_VALUE,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ BTREE_USER_VERSION },
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+#if defined(SQLITE_DEBUG)
+  { /* zName:     */ "vdbe_addoptrace",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_VdbeAddopTrace },
+  { /* zName:     */ "vdbe_debug",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_SqlTrace|SQLITE_VdbeListing|SQLITE_VdbeTrace },
+  { /* zName:     */ "vdbe_eqp",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_VdbeEQP },
+  { /* zName:     */ "vdbe_listing",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_VdbeListing },
+  { /* zName:     */ "vdbe_trace",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_VdbeTrace },
+#endif
+#endif
+#if !defined(SQLITE_OMIT_WAL)
+  { /* zName:     */ "wal_autocheckpoint",
+    /* ePragTyp:  */ PragTyp_WAL_AUTOCHECKPOINT,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ 0 },
+  { /* zName:     */ "wal_checkpoint",
+    /* ePragTyp:  */ PragTyp_WAL_CHECKPOINT,
+    /* ePragFlag: */ PragFlag_NeedSchema,
+    /* iArg:      */ 0 },
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+  { /* zName:     */ "writable_schema",
+    /* ePragTyp:  */ PragTyp_FLAG,
+    /* ePragFlag: */ 0,
+    /* iArg:      */ SQLITE_WriteSchema|SQLITE_RecoveryMode },
+#endif
+};
+/* Number of pragmas: 60 on by default, 73 total. */
+
+/************** End of pragma.h **********************************************/
+/************** Continuing where we left off in pragma.c *********************/
+
+/*
+** Interpret the given string as a safety level.  Return 0 for OFF,
+** 1 for ON or NORMAL, 2 for FULL, and 3 for EXTRA.  Return 1 for an empty or 
+** unrecognized string argument.  The FULL and EXTRA option is disallowed
+** if the omitFull parameter it 1.
+**
+** Note that the values returned are one less that the values that
+** should be passed into sqlite3BtreeSetSafetyLevel().  The is done
+** to support legacy SQL code.  The safety level used to be boolean
+** and older scripts may have used numbers 0 for OFF and 1 for ON.
+*/
+static u8 getSafetyLevel(const char *z, int omitFull, u8 dflt){
+                             /* 123456789 123456789 123 */
+  static const char zText[] = "onoffalseyestruextrafull";
+  static const u8 iOffset[] = {0, 1, 2,  4,    9,  12,  15,   20};
+  static const u8 iLength[] = {2, 2, 3,  5,    3,   4,   5,    4};
+  static const u8 iValue[] =  {1, 0, 0,  0,    1,   1,   3,    2};
+                            /* on no off false yes true extra full */
+  int i, n;
+  if( sqlite3Isdigit(*z) ){
+    return (u8)sqlite3Atoi(z);
+  }
+  n = sqlite3Strlen30(z);
+  for(i=0; i<ArraySize(iLength); i++){
+    if( iLength[i]==n && sqlite3StrNICmp(&zText[iOffset[i]],z,n)==0
+     && (!omitFull || iValue[i]<=1)
+    ){
+      return iValue[i];
+    }
+  }
+  return dflt;
+}
+
+/*
+** Interpret the given string as a boolean value.
+*/
+SQLITE_PRIVATE u8 sqlite3GetBoolean(const char *z, u8 dflt){
+  return getSafetyLevel(z,1,dflt)!=0;
+}
+
+/* The sqlite3GetBoolean() function is used by other modules but the
+** remainder of this file is specific to PRAGMA processing.  So omit
+** the rest of the file if PRAGMAs are omitted from the build.
+*/
+#if !defined(SQLITE_OMIT_PRAGMA)
+
+/*
+** Interpret the given string as a locking mode value.
+*/
+static int getLockingMode(const char *z){
+  if( z ){
+    if( 0==sqlite3StrICmp(z, "exclusive") ) return PAGER_LOCKINGMODE_EXCLUSIVE;
+    if( 0==sqlite3StrICmp(z, "normal") ) return PAGER_LOCKINGMODE_NORMAL;
+  }
+  return PAGER_LOCKINGMODE_QUERY;
+}
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+/*
+** Interpret the given string as an auto-vacuum mode value.
+**
+** The following strings, "none", "full" and "incremental" are 
+** acceptable, as are their numeric equivalents: 0, 1 and 2 respectively.
+*/
+static int getAutoVacuum(const char *z){
+  int i;
+  if( 0==sqlite3StrICmp(z, "none") ) return BTREE_AUTOVACUUM_NONE;
+  if( 0==sqlite3StrICmp(z, "full") ) return BTREE_AUTOVACUUM_FULL;
+  if( 0==sqlite3StrICmp(z, "incremental") ) return BTREE_AUTOVACUUM_INCR;
+  i = sqlite3Atoi(z);
+  return (u8)((i>=0&&i<=2)?i:0);
+}
+#endif /* ifndef SQLITE_OMIT_AUTOVACUUM */
+
+#ifndef SQLITE_OMIT_PAGER_PRAGMAS
+/*
+** Interpret the given string as a temp db location. Return 1 for file
+** backed temporary databases, 2 for the Red-Black tree in memory database
+** and 0 to use the compile-time default.
+*/
+static int getTempStore(const char *z){
+  if( z[0]>='0' && z[0]<='2' ){
+    return z[0] - '0';
+  }else if( sqlite3StrICmp(z, "file")==0 ){
+    return 1;
+  }else if( sqlite3StrICmp(z, "memory")==0 ){
+    return 2;
+  }else{
+    return 0;
+  }
+}
+#endif /* SQLITE_PAGER_PRAGMAS */
+
+#ifndef SQLITE_OMIT_PAGER_PRAGMAS
+/*
+** Invalidate temp storage, either when the temp storage is changed
+** from default, or when 'file' and the temp_store_directory has changed
+*/
+static int invalidateTempStorage(Parse *pParse){
+  sqlite3 *db = pParse->db;
+  if( db->aDb[1].pBt!=0 ){
+    if( !db->autoCommit || sqlite3BtreeIsInReadTrans(db->aDb[1].pBt) ){
+      sqlite3ErrorMsg(pParse, "temporary storage cannot be changed "
+        "from within a transaction");
+      return SQLITE_ERROR;
+    }
+    sqlite3BtreeClose(db->aDb[1].pBt);
+    db->aDb[1].pBt = 0;
+    sqlite3ResetAllSchemasOfConnection(db);
+  }
+  return SQLITE_OK;
+}
+#endif /* SQLITE_PAGER_PRAGMAS */
+
+#ifndef SQLITE_OMIT_PAGER_PRAGMAS
+/*
+** If the TEMP database is open, close it and mark the database schema
+** as needing reloading.  This must be done when using the SQLITE_TEMP_STORE
+** or DEFAULT_TEMP_STORE pragmas.
+*/
+static int changeTempStorage(Parse *pParse, const char *zStorageType){
+  int ts = getTempStore(zStorageType);
+  sqlite3 *db = pParse->db;
+  if( db->temp_store==ts ) return SQLITE_OK;
+  if( invalidateTempStorage( pParse ) != SQLITE_OK ){
+    return SQLITE_ERROR;
+  }
+  db->temp_store = (u8)ts;
+  return SQLITE_OK;
+}
+#endif /* SQLITE_PAGER_PRAGMAS */
+
+/*
+** Set the names of the first N columns to the values in azCol[]
+*/
+static void setAllColumnNames(
+  Vdbe *v,               /* The query under construction */
+  int N,                 /* Number of columns */
+  const char **azCol     /* Names of columns */
+){
+  int i;
+  sqlite3VdbeSetNumCols(v, N);
+  for(i=0; i<N; i++){
+    sqlite3VdbeSetColName(v, i, COLNAME_NAME, azCol[i], SQLITE_STATIC);
+  }
+}
+static void setOneColumnName(Vdbe *v, const char *z){
+  setAllColumnNames(v, 1, &z);
+}
+
+/*
+** Generate code to return a single integer value.
+*/
+static void returnSingleInt(Vdbe *v, const char *zLabel, i64 value){
+  sqlite3VdbeAddOp4Dup8(v, OP_Int64, 0, 1, 0, (const u8*)&value, P4_INT64);
+  setOneColumnName(v, zLabel);
+  sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 1);
+}
+
+/*
+** Generate code to return a single text value.
+*/
+static void returnSingleText(
+  Vdbe *v,                /* Prepared statement under construction */
+  const char *zLabel,     /* Name of the result column */
+  const char *zValue      /* Value to be returned */
+){
+  if( zValue ){
+    sqlite3VdbeLoadString(v, 1, (const char*)zValue);
+    setOneColumnName(v, zLabel);
+    sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 1);
+  }
+}
+
+
+/*
+** Set the safety_level and pager flags for pager iDb.  Or if iDb<0
+** set these values for all pagers.
+*/
+#ifndef SQLITE_OMIT_PAGER_PRAGMAS
+static void setAllPagerFlags(sqlite3 *db){
+  if( db->autoCommit ){
+    Db *pDb = db->aDb;
+    int n = db->nDb;
+    assert( SQLITE_FullFSync==PAGER_FULLFSYNC );
+    assert( SQLITE_CkptFullFSync==PAGER_CKPT_FULLFSYNC );
+    assert( SQLITE_CacheSpill==PAGER_CACHESPILL );
+    assert( (PAGER_FULLFSYNC | PAGER_CKPT_FULLFSYNC | PAGER_CACHESPILL)
+             ==  PAGER_FLAGS_MASK );
+    assert( (pDb->safety_level & PAGER_SYNCHRONOUS_MASK)==pDb->safety_level );
+    while( (n--) > 0 ){
+      if( pDb->pBt ){
+        sqlite3BtreeSetPagerFlags(pDb->pBt,
+                 pDb->safety_level | (db->flags & PAGER_FLAGS_MASK) );
+      }
+      pDb++;
+    }
+  }
+}
+#else
+# define setAllPagerFlags(X)  /* no-op */
+#endif
+
+
+/*
+** Return a human-readable name for a constraint resolution action.
+*/
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+static const char *actionName(u8 action){
+  const char *zName;
+  switch( action ){
+    case OE_SetNull:  zName = "SET NULL";        break;
+    case OE_SetDflt:  zName = "SET DEFAULT";     break;
+    case OE_Cascade:  zName = "CASCADE";         break;
+    case OE_Restrict: zName = "RESTRICT";        break;
+    default:          zName = "NO ACTION";  
+                      assert( action==OE_None ); break;
+  }
+  return zName;
+}
+#endif
+
+
+/*
+** Parameter eMode must be one of the PAGER_JOURNALMODE_XXX constants
+** defined in pager.h. This function returns the associated lowercase
+** journal-mode name.
+*/
+SQLITE_PRIVATE const char *sqlite3JournalModename(int eMode){
+  static char * const azModeName[] = {
+    "delete", "persist", "off", "truncate", "memory"
+#ifndef SQLITE_OMIT_WAL
+     , "wal"
+#endif
+  };
+  assert( PAGER_JOURNALMODE_DELETE==0 );
+  assert( PAGER_JOURNALMODE_PERSIST==1 );
+  assert( PAGER_JOURNALMODE_OFF==2 );
+  assert( PAGER_JOURNALMODE_TRUNCATE==3 );
+  assert( PAGER_JOURNALMODE_MEMORY==4 );
+  assert( PAGER_JOURNALMODE_WAL==5 );
+  assert( eMode>=0 && eMode<=ArraySize(azModeName) );
+
+  if( eMode==ArraySize(azModeName) ) return 0;
+  return azModeName[eMode];
+}
+
+/*
+** Process a pragma statement.  
+**
+** Pragmas are of this form:
+**
+**      PRAGMA [schema.]id [= value]
+**
+** The identifier might also be a string.  The value is a string, and
+** identifier, or a number.  If minusFlag is true, then the value is
+** a number that was preceded by a minus sign.
+**
+** If the left side is "database.id" then pId1 is the database name
+** and pId2 is the id.  If the left side is just "id" then pId1 is the
+** id and pId2 is any empty string.
+*/
+SQLITE_PRIVATE void sqlite3Pragma(
+  Parse *pParse, 
+  Token *pId1,        /* First part of [schema.]id field */
+  Token *pId2,        /* Second part of [schema.]id field, or NULL */
+  Token *pValue,      /* Token for <value>, or NULL */
+  int minusFlag       /* True if a '-' sign preceded <value> */
+){
+  char *zLeft = 0;       /* Nul-terminated UTF-8 string <id> */
+  char *zRight = 0;      /* Nul-terminated UTF-8 string <value>, or NULL */
+  const char *zDb = 0;   /* The database name */
+  Token *pId;            /* Pointer to <id> token */
+  char *aFcntl[4];       /* Argument to SQLITE_FCNTL_PRAGMA */
+  int iDb;               /* Database index for <database> */
+  int lwr, upr, mid = 0;       /* Binary search bounds */
+  int rc;                      /* return value form SQLITE_FCNTL_PRAGMA */
+  sqlite3 *db = pParse->db;    /* The database connection */
+  Db *pDb;                     /* The specific database being pragmaed */
+  Vdbe *v = sqlite3GetVdbe(pParse);  /* Prepared statement */
+  const struct sPragmaNames *pPragma;
+/* BEGIN SQLCIPHER */
+#ifdef SQLITE_HAS_CODEC
+  extern int sqlcipher_codec_pragma(sqlite3*, int, Parse *, const char *, const char *);
+#endif
+/* END SQLCIPHER */
+
+  if( v==0 ) return;
+  sqlite3VdbeRunOnlyOnce(v);
+  pParse->nMem = 2;
+
+  /* Interpret the [schema.] part of the pragma statement. iDb is the
+  ** index of the database this pragma is being applied to in db.aDb[]. */
+  iDb = sqlite3TwoPartName(pParse, pId1, pId2, &pId);
+  if( iDb<0 ) return;
+  pDb = &db->aDb[iDb];
+
+  /* If the temp database has been explicitly named as part of the 
+  ** pragma, make sure it is open. 
+  */
+  if( iDb==1 && sqlite3OpenTempDatabase(pParse) ){
+    return;
+  }
+
+  zLeft = sqlite3NameFromToken(db, pId);
+  if( !zLeft ) return;
+  if( minusFlag ){
+    zRight = sqlite3MPrintf(db, "-%T", pValue);
+  }else{
+    zRight = sqlite3NameFromToken(db, pValue);
+  }
+
+  assert( pId2 );
+  zDb = pId2->n>0 ? pDb->zDbSName : 0;
+  if( sqlite3AuthCheck(pParse, SQLITE_PRAGMA, zLeft, zRight, zDb) ){
+    goto pragma_out;
+  }
+
+  /* Send an SQLITE_FCNTL_PRAGMA file-control to the underlying VFS
+  ** connection.  If it returns SQLITE_OK, then assume that the VFS
+  ** handled the pragma and generate a no-op prepared statement.
+  **
+  ** IMPLEMENTATION-OF: R-12238-55120 Whenever a PRAGMA statement is parsed,
+  ** an SQLITE_FCNTL_PRAGMA file control is sent to the open sqlite3_file
+  ** object corresponding to the database file to which the pragma
+  ** statement refers.
+  **
+  ** IMPLEMENTATION-OF: R-29875-31678 The argument to the SQLITE_FCNTL_PRAGMA
+  ** file control is an array of pointers to strings (char**) in which the
+  ** second element of the array is the name of the pragma and the third
+  ** element is the argument to the pragma or NULL if the pragma has no
+  ** argument.
+  */
+  aFcntl[0] = 0;
+  aFcntl[1] = zLeft;
+  aFcntl[2] = zRight;
+  aFcntl[3] = 0;
+  db->busyHandler.nBusy = 0;
+  rc = sqlite3_file_control(db, zDb, SQLITE_FCNTL_PRAGMA, (void*)aFcntl);
+  if( rc==SQLITE_OK ){
+    returnSingleText(v, "result", aFcntl[0]);
+    sqlite3_free(aFcntl[0]);
+    goto pragma_out;
+  }
+  if( rc!=SQLITE_NOTFOUND ){
+    if( aFcntl[0] ){
+      sqlite3ErrorMsg(pParse, "%s", aFcntl[0]);
+      sqlite3_free(aFcntl[0]);
+    }
+    pParse->nErr++;
+    pParse->rc = rc;
+
+    goto pragma_out;
+  }
+
+/* BEGIN SQLCIPHER */
+#ifdef SQLITE_HAS_CODEC
+  if(sqlcipher_codec_pragma(db, iDb, pParse, zLeft, zRight)) { 
+    /* sqlcipher_codec_pragma executes internal */
+    goto pragma_out;
+  }
+#endif
+/* END SQLCIPHER */  
+
+  /* Locate the pragma in the lookup table */
+  lwr = 0;
+  upr = ArraySize(aPragmaNames)-1;
+  while( lwr<=upr ){
+    mid = (lwr+upr)/2;
+    rc = sqlite3_stricmp(zLeft, aPragmaNames[mid].zName);
+    if( rc==0 ) break;
+    if( rc<0 ){
+      upr = mid - 1;
+    }else{
+      lwr = mid + 1;
+    }
+  }
+  if( lwr>upr ) goto pragma_out;
+  pPragma = &aPragmaNames[mid];
+
+  /* Make sure the database schema is loaded if the pragma requires that */
+  if( (pPragma->mPragFlag & PragFlag_NeedSchema)!=0 ){
+    if( sqlite3ReadSchema(pParse) ) goto pragma_out;
+  }
+
+  /* Jump to the appropriate pragma handler */
+  switch( pPragma->ePragTyp ){
+  
+#if !defined(SQLITE_OMIT_PAGER_PRAGMAS) && !defined(SQLITE_OMIT_DEPRECATED)
+  /*
+  **  PRAGMA [schema.]default_cache_size
+  **  PRAGMA [schema.]default_cache_size=N
+  **
+  ** The first form reports the current persistent setting for the
+  ** page cache size.  The value returned is the maximum number of
+  ** pages in the page cache.  The second form sets both the current
+  ** page cache size value and the persistent page cache size value
+  ** stored in the database file.
+  **
+  ** Older versions of SQLite would set the default cache size to a
+  ** negative number to indicate synchronous=OFF.  These days, synchronous
+  ** is always on by default regardless of the sign of the default cache
+  ** size.  But continue to take the absolute value of the default cache
+  ** size of historical compatibility.
+  */
+  case PragTyp_DEFAULT_CACHE_SIZE: {
+    static const int iLn = VDBE_OFFSET_LINENO(2);
+    static const VdbeOpList getCacheSize[] = {
+      { OP_Transaction, 0, 0,        0},                         /* 0 */
+      { OP_ReadCookie,  0, 1,        BTREE_DEFAULT_CACHE_SIZE},  /* 1 */
+      { OP_IfPos,       1, 8,        0},
+      { OP_Integer,     0, 2,        0},
+      { OP_Subtract,    1, 2,        1},
+      { OP_IfPos,       1, 8,        0},
+      { OP_Integer,     0, 1,        0},                         /* 6 */
+      { OP_Noop,        0, 0,        0},
+      { OP_ResultRow,   1, 1,        0},
+    };
+    VdbeOp *aOp;
+    sqlite3VdbeUsesBtree(v, iDb);
+    if( !zRight ){
+      setOneColumnName(v, "cache_size");
+      pParse->nMem += 2;
+      sqlite3VdbeVerifyNoMallocRequired(v, ArraySize(getCacheSize));
+      aOp = sqlite3VdbeAddOpList(v, ArraySize(getCacheSize), getCacheSize, iLn);
+      if( ONLY_IF_REALLOC_STRESS(aOp==0) ) break;
+      aOp[0].p1 = iDb;
+      aOp[1].p1 = iDb;
+      aOp[6].p1 = SQLITE_DEFAULT_CACHE_SIZE;
+    }else{
+      int size = sqlite3AbsInt32(sqlite3Atoi(zRight));
+      sqlite3BeginWriteOperation(pParse, 0, iDb);
+      sqlite3VdbeAddOp3(v, OP_SetCookie, iDb, BTREE_DEFAULT_CACHE_SIZE, size);
+      assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+      pDb->pSchema->cache_size = size;
+      sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size);
+    }
+    break;
+  }
+#endif /* !SQLITE_OMIT_PAGER_PRAGMAS && !SQLITE_OMIT_DEPRECATED */
+
+#if !defined(SQLITE_OMIT_PAGER_PRAGMAS)
+  /*
+  **  PRAGMA [schema.]page_size
+  **  PRAGMA [schema.]page_size=N
+  **
+  ** The first form reports the current setting for the
+  ** database page size in bytes.  The second form sets the
+  ** database page size value.  The value can only be set if
+  ** the database has not yet been created.
+  */
+  case PragTyp_PAGE_SIZE: {
+    Btree *pBt = pDb->pBt;
+    assert( pBt!=0 );
+    if( !zRight ){
+      int size = ALWAYS(pBt) ? sqlite3BtreeGetPageSize(pBt) : 0;
+      returnSingleInt(v, "page_size", size);
+    }else{
+      /* Malloc may fail when setting the page-size, as there is an internal
+      ** buffer that the pager module resizes using sqlite3_realloc().
+      */
+      db->nextPagesize = sqlite3Atoi(zRight);
+      if( SQLITE_NOMEM==sqlite3BtreeSetPageSize(pBt, db->nextPagesize,-1,0) ){
+        sqlite3OomFault(db);
+      }
+    }
+    break;
+  }
+
+  /*
+  **  PRAGMA [schema.]secure_delete
+  **  PRAGMA [schema.]secure_delete=ON/OFF
+  **
+  ** The first form reports the current setting for the
+  ** secure_delete flag.  The second form changes the secure_delete
+  ** flag setting and reports thenew value.
+  */
+  case PragTyp_SECURE_DELETE: {
+    Btree *pBt = pDb->pBt;
+    int b = -1;
+    assert( pBt!=0 );
+    if( zRight ){
+      b = sqlite3GetBoolean(zRight, 0);
+    }
+    if( pId2->n==0 && b>=0 ){
+      int ii;
+      for(ii=0; ii<db->nDb; ii++){
+        sqlite3BtreeSecureDelete(db->aDb[ii].pBt, b);
+      }
+    }
+    b = sqlite3BtreeSecureDelete(pBt, b);
+    returnSingleInt(v, "secure_delete", b);
+    break;
+  }
+
+  /*
+  **  PRAGMA [schema.]max_page_count
+  **  PRAGMA [schema.]max_page_count=N
+  **
+  ** The first form reports the current setting for the
+  ** maximum number of pages in the database file.  The 
+  ** second form attempts to change this setting.  Both
+  ** forms return the current setting.
+  **
+  ** The absolute value of N is used.  This is undocumented and might
+  ** change.  The only purpose is to provide an easy way to test
+  ** the sqlite3AbsInt32() function.
+  **
+  **  PRAGMA [schema.]page_count
+  **
+  ** Return the number of pages in the specified database.
+  */
+  case PragTyp_PAGE_COUNT: {
+    int iReg;
+    sqlite3CodeVerifySchema(pParse, iDb);
+    iReg = ++pParse->nMem;
+    if( sqlite3Tolower(zLeft[0])=='p' ){
+      sqlite3VdbeAddOp2(v, OP_Pagecount, iDb, iReg);
+    }else{
+      sqlite3VdbeAddOp3(v, OP_MaxPgcnt, iDb, iReg, 
+                        sqlite3AbsInt32(sqlite3Atoi(zRight)));
+    }
+    sqlite3VdbeAddOp2(v, OP_ResultRow, iReg, 1);
+    sqlite3VdbeSetNumCols(v, 1);
+    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, zLeft, SQLITE_TRANSIENT);
+    break;
+  }
+
+  /*
+  **  PRAGMA [schema.]locking_mode
+  **  PRAGMA [schema.]locking_mode = (normal|exclusive)
+  */
+  case PragTyp_LOCKING_MODE: {
+    const char *zRet = "normal";
+    int eMode = getLockingMode(zRight);
+
+    if( pId2->n==0 && eMode==PAGER_LOCKINGMODE_QUERY ){
+      /* Simple "PRAGMA locking_mode;" statement. This is a query for
+      ** the current default locking mode (which may be different to
+      ** the locking-mode of the main database).
+      */
+      eMode = db->dfltLockMode;
+    }else{
+      Pager *pPager;
+      if( pId2->n==0 ){
+        /* This indicates that no database name was specified as part
+        ** of the PRAGMA command. In this case the locking-mode must be
+        ** set on all attached databases, as well as the main db file.
+        **
+        ** Also, the sqlite3.dfltLockMode variable is set so that
+        ** any subsequently attached databases also use the specified
+        ** locking mode.
+        */
+        int ii;
+        assert(pDb==&db->aDb[0]);
+        for(ii=2; ii<db->nDb; ii++){
+          pPager = sqlite3BtreePager(db->aDb[ii].pBt);
+          sqlite3PagerLockingMode(pPager, eMode);
+        }
+        db->dfltLockMode = (u8)eMode;
+      }
+      pPager = sqlite3BtreePager(pDb->pBt);
+      eMode = sqlite3PagerLockingMode(pPager, eMode);
+    }
+
+    assert( eMode==PAGER_LOCKINGMODE_NORMAL
+            || eMode==PAGER_LOCKINGMODE_EXCLUSIVE );
+    if( eMode==PAGER_LOCKINGMODE_EXCLUSIVE ){
+      zRet = "exclusive";
+    }
+    returnSingleText(v, "locking_mode", zRet);
+    break;
+  }
+
+  /*
+  **  PRAGMA [schema.]journal_mode
+  **  PRAGMA [schema.]journal_mode =
+  **                      (delete|persist|off|truncate|memory|wal|off)
+  */
+  case PragTyp_JOURNAL_MODE: {
+    int eMode;        /* One of the PAGER_JOURNALMODE_XXX symbols */
+    int ii;           /* Loop counter */
+
+    setOneColumnName(v, "journal_mode");
+    if( zRight==0 ){
+      /* If there is no "=MODE" part of the pragma, do a query for the
+      ** current mode */
+      eMode = PAGER_JOURNALMODE_QUERY;
+    }else{
+      const char *zMode;
+      int n = sqlite3Strlen30(zRight);
+      for(eMode=0; (zMode = sqlite3JournalModename(eMode))!=0; eMode++){
+        if( sqlite3StrNICmp(zRight, zMode, n)==0 ) break;
+      }
+      if( !zMode ){
+        /* If the "=MODE" part does not match any known journal mode,
+        ** then do a query */
+        eMode = PAGER_JOURNALMODE_QUERY;
+      }
+    }
+    if( eMode==PAGER_JOURNALMODE_QUERY && pId2->n==0 ){
+      /* Convert "PRAGMA journal_mode" into "PRAGMA main.journal_mode" */
+      iDb = 0;
+      pId2->n = 1;
+    }
+    for(ii=db->nDb-1; ii>=0; ii--){
+      if( db->aDb[ii].pBt && (ii==iDb || pId2->n==0) ){
+        sqlite3VdbeUsesBtree(v, ii);
+        sqlite3VdbeAddOp3(v, OP_JournalMode, ii, 1, eMode);
+      }
+    }
+    sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 1);
+    break;
+  }
+
+  /*
+  **  PRAGMA [schema.]journal_size_limit
+  **  PRAGMA [schema.]journal_size_limit=N
+  **
+  ** Get or set the size limit on rollback journal files.
+  */
+  case PragTyp_JOURNAL_SIZE_LIMIT: {
+    Pager *pPager = sqlite3BtreePager(pDb->pBt);
+    i64 iLimit = -2;
+    if( zRight ){
+      sqlite3DecOrHexToI64(zRight, &iLimit);
+      if( iLimit<-1 ) iLimit = -1;
+    }
+    iLimit = sqlite3PagerJournalSizeLimit(pPager, iLimit);
+    returnSingleInt(v, "journal_size_limit", iLimit);
+    break;
+  }
+
+#endif /* SQLITE_OMIT_PAGER_PRAGMAS */
+
+  /*
+  **  PRAGMA [schema.]auto_vacuum
+  **  PRAGMA [schema.]auto_vacuum=N
+  **
+  ** Get or set the value of the database 'auto-vacuum' parameter.
+  ** The value is one of:  0 NONE 1 FULL 2 INCREMENTAL
+  */
+#ifndef SQLITE_OMIT_AUTOVACUUM
+  case PragTyp_AUTO_VACUUM: {
+    Btree *pBt = pDb->pBt;
+    assert( pBt!=0 );
+    if( !zRight ){
+      returnSingleInt(v, "auto_vacuum", sqlite3BtreeGetAutoVacuum(pBt));
+    }else{
+      int eAuto = getAutoVacuum(zRight);
+      assert( eAuto>=0 && eAuto<=2 );
+      db->nextAutovac = (u8)eAuto;
+      /* Call SetAutoVacuum() to set initialize the internal auto and
+      ** incr-vacuum flags. This is required in case this connection
+      ** creates the database file. It is important that it is created
+      ** as an auto-vacuum capable db.
+      */
+      rc = sqlite3BtreeSetAutoVacuum(pBt, eAuto);
+      if( rc==SQLITE_OK && (eAuto==1 || eAuto==2) ){
+        /* When setting the auto_vacuum mode to either "full" or 
+        ** "incremental", write the value of meta[6] in the database
+        ** file. Before writing to meta[6], check that meta[3] indicates
+        ** that this really is an auto-vacuum capable database.
+        */
+        static const int iLn = VDBE_OFFSET_LINENO(2);
+        static const VdbeOpList setMeta6[] = {
+          { OP_Transaction,    0,         1,                 0},    /* 0 */
+          { OP_ReadCookie,     0,         1,         BTREE_LARGEST_ROOT_PAGE},
+          { OP_If,             1,         0,                 0},    /* 2 */
+          { OP_Halt,           SQLITE_OK, OE_Abort,          0},    /* 3 */
+          { OP_SetCookie,      0,         BTREE_INCR_VACUUM, 0},    /* 4 */
+        };
+        VdbeOp *aOp;
+        int iAddr = sqlite3VdbeCurrentAddr(v);
+        sqlite3VdbeVerifyNoMallocRequired(v, ArraySize(setMeta6));
+        aOp = sqlite3VdbeAddOpList(v, ArraySize(setMeta6), setMeta6, iLn);
+        if( ONLY_IF_REALLOC_STRESS(aOp==0) ) break;
+        aOp[0].p1 = iDb;
+        aOp[1].p1 = iDb;
+        aOp[2].p2 = iAddr+4;
+        aOp[4].p1 = iDb;
+        aOp[4].p3 = eAuto - 1;
+        sqlite3VdbeUsesBtree(v, iDb);
+      }
+    }
+    break;
+  }
+#endif
+
+  /*
+  **  PRAGMA [schema.]incremental_vacuum(N)
+  **
+  ** Do N steps of incremental vacuuming on a database.
+  */
+#ifndef SQLITE_OMIT_AUTOVACUUM
+  case PragTyp_INCREMENTAL_VACUUM: {
+    int iLimit, addr;
+    if( zRight==0 || !sqlite3GetInt32(zRight, &iLimit) || iLimit<=0 ){
+      iLimit = 0x7fffffff;
+    }
+    sqlite3BeginWriteOperation(pParse, 0, iDb);
+    sqlite3VdbeAddOp2(v, OP_Integer, iLimit, 1);
+    addr = sqlite3VdbeAddOp1(v, OP_IncrVacuum, iDb); VdbeCoverage(v);
+    sqlite3VdbeAddOp1(v, OP_ResultRow, 1);
+    sqlite3VdbeAddOp2(v, OP_AddImm, 1, -1);
+    sqlite3VdbeAddOp2(v, OP_IfPos, 1, addr); VdbeCoverage(v);
+    sqlite3VdbeJumpHere(v, addr);
+    break;
+  }
+#endif
+
+#ifndef SQLITE_OMIT_PAGER_PRAGMAS
+  /*
+  **  PRAGMA [schema.]cache_size
+  **  PRAGMA [schema.]cache_size=N
+  **
+  ** The first form reports the current local setting for the
+  ** page cache size. The second form sets the local
+  ** page cache size value.  If N is positive then that is the
+  ** number of pages in the cache.  If N is negative, then the
+  ** number of pages is adjusted so that the cache uses -N kibibytes
+  ** of memory.
+  */
+  case PragTyp_CACHE_SIZE: {
+    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+    if( !zRight ){
+      returnSingleInt(v, "cache_size", pDb->pSchema->cache_size);
+    }else{
+      int size = sqlite3Atoi(zRight);
+      pDb->pSchema->cache_size = size;
+      sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size);
+    }
+    break;
+  }
+
+  /*
+  **  PRAGMA [schema.]cache_spill
+  **  PRAGMA cache_spill=BOOLEAN
+  **  PRAGMA [schema.]cache_spill=N
+  **
+  ** The first form reports the current local setting for the
+  ** page cache spill size. The second form turns cache spill on
+  ** or off.  When turnning cache spill on, the size is set to the
+  ** current cache_size.  The third form sets a spill size that
+  ** may be different form the cache size.
+  ** If N is positive then that is the
+  ** number of pages in the cache.  If N is negative, then the
+  ** number of pages is adjusted so that the cache uses -N kibibytes
+  ** of memory.
+  **
+  ** If the number of cache_spill pages is less then the number of
+  ** cache_size pages, no spilling occurs until the page count exceeds
+  ** the number of cache_size pages.
+  **
+  ** The cache_spill=BOOLEAN setting applies to all attached schemas,
+  ** not just the schema specified.
+  */
+  case PragTyp_CACHE_SPILL: {
+    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+    if( !zRight ){
+      returnSingleInt(v, "cache_spill", 
+         (db->flags & SQLITE_CacheSpill)==0 ? 0 : 
+            sqlite3BtreeSetSpillSize(pDb->pBt,0));
+    }else{
+      int size = 1;
+      if( sqlite3GetInt32(zRight, &size) ){
+        sqlite3BtreeSetSpillSize(pDb->pBt, size);
+      }
+      if( sqlite3GetBoolean(zRight, size!=0) ){
+        db->flags |= SQLITE_CacheSpill;
+      }else{
+        db->flags &= ~SQLITE_CacheSpill;
+      }
+      setAllPagerFlags(db);
+    }
+    break;
+  }
+
+  /*
+  **  PRAGMA [schema.]mmap_size(N)
+  **
+  ** Used to set mapping size limit. The mapping size limit is
+  ** used to limit the aggregate size of all memory mapped regions of the
+  ** database file. If this parameter is set to zero, then memory mapping
+  ** is not used at all.  If N is negative, then the default memory map
+  ** limit determined by sqlite3_config(SQLITE_CONFIG_MMAP_SIZE) is set.
+  ** The parameter N is measured in bytes.
+  **
+  ** This value is advisory.  The underlying VFS is free to memory map
+  ** as little or as much as it wants.  Except, if N is set to 0 then the
+  ** upper layers will never invoke the xFetch interfaces to the VFS.
+  */
+  case PragTyp_MMAP_SIZE: {
+    sqlite3_int64 sz;
+#if SQLITE_MAX_MMAP_SIZE>0
+    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+    if( zRight ){
+      int ii;
+      sqlite3DecOrHexToI64(zRight, &sz);
+      if( sz<0 ) sz = sqlite3GlobalConfig.szMmap;
+      if( pId2->n==0 ) db->szMmap = sz;
+      for(ii=db->nDb-1; ii>=0; ii--){
+        if( db->aDb[ii].pBt && (ii==iDb || pId2->n==0) ){
+          sqlite3BtreeSetMmapLimit(db->aDb[ii].pBt, sz);
+        }
+      }
+    }
+    sz = -1;
+    rc = sqlite3_file_control(db, zDb, SQLITE_FCNTL_MMAP_SIZE, &sz);
+#else
+    sz = 0;
+    rc = SQLITE_OK;
+#endif
+    if( rc==SQLITE_OK ){
+      returnSingleInt(v, "mmap_size", sz);
+    }else if( rc!=SQLITE_NOTFOUND ){
+      pParse->nErr++;
+      pParse->rc = rc;
+    }
+    break;
+  }
+
+  /*
+  **   PRAGMA temp_store
+  **   PRAGMA temp_store = "default"|"memory"|"file"
+  **
+  ** Return or set the local value of the temp_store flag.  Changing
+  ** the local value does not make changes to the disk file and the default
+  ** value will be restored the next time the database is opened.
+  **
+  ** Note that it is possible for the library compile-time options to
+  ** override this setting
+  */
+  case PragTyp_TEMP_STORE: {
+    if( !zRight ){
+      returnSingleInt(v, "temp_store", db->temp_store);
+    }else{
+      changeTempStorage(pParse, zRight);
+    }
+    break;
+  }
+
+  /*
+  **   PRAGMA temp_store_directory
+  **   PRAGMA temp_store_directory = ""|"directory_name"
+  **
+  ** Return or set the local value of the temp_store_directory flag.  Changing
+  ** the value sets a specific directory to be used for temporary files.
+  ** Setting to a null string reverts to the default temporary directory search.
+  ** If temporary directory is changed, then invalidateTempStorage.
+  **
+  */
+  case PragTyp_TEMP_STORE_DIRECTORY: {
+    if( !zRight ){
+      returnSingleText(v, "temp_store_directory", sqlite3_temp_directory);
+    }else{
+#ifndef SQLITE_OMIT_WSD
+      if( zRight[0] ){
+        int res;
+        rc = sqlite3OsAccess(db->pVfs, zRight, SQLITE_ACCESS_READWRITE, &res);
+        if( rc!=SQLITE_OK || res==0 ){
+          sqlite3ErrorMsg(pParse, "not a writable directory");
+          goto pragma_out;
+        }
+      }
+      if( SQLITE_TEMP_STORE==0
+       || (SQLITE_TEMP_STORE==1 && db->temp_store<=1)
+       || (SQLITE_TEMP_STORE==2 && db->temp_store==1)
+      ){
+        invalidateTempStorage(pParse);
+      }
+      sqlite3_free(sqlite3_temp_directory);
+      if( zRight[0] ){
+        sqlite3_temp_directory = sqlite3_mprintf("%s", zRight);
+      }else{
+        sqlite3_temp_directory = 0;
+      }
+#endif /* SQLITE_OMIT_WSD */
+    }
+    break;
+  }
+
+#if SQLITE_OS_WIN
+  /*
+  **   PRAGMA data_store_directory
+  **   PRAGMA data_store_directory = ""|"directory_name"
+  **
+  ** Return or set the local value of the data_store_directory flag.  Changing
+  ** the value sets a specific directory to be used for database files that
+  ** were specified with a relative pathname.  Setting to a null string reverts
+  ** to the default database directory, which for database files specified with
+  ** a relative path will probably be based on the current directory for the
+  ** process.  Database file specified with an absolute path are not impacted
+  ** by this setting, regardless of its value.
+  **
+  */
+  case PragTyp_DATA_STORE_DIRECTORY: {
+    if( !zRight ){
+      returnSingleText(v, "data_store_directory", sqlite3_data_directory);
+    }else{
+#ifndef SQLITE_OMIT_WSD
+      if( zRight[0] ){
+        int res;
+        rc = sqlite3OsAccess(db->pVfs, zRight, SQLITE_ACCESS_READWRITE, &res);
+        if( rc!=SQLITE_OK || res==0 ){
+          sqlite3ErrorMsg(pParse, "not a writable directory");
+          goto pragma_out;
+        }
+      }
+      sqlite3_free(sqlite3_data_directory);
+      if( zRight[0] ){
+        sqlite3_data_directory = sqlite3_mprintf("%s", zRight);
+      }else{
+        sqlite3_data_directory = 0;
+      }
+#endif /* SQLITE_OMIT_WSD */
+    }
+    break;
+  }
+#endif
+
+#if SQLITE_ENABLE_LOCKING_STYLE
+  /*
+  **   PRAGMA [schema.]lock_proxy_file
+  **   PRAGMA [schema.]lock_proxy_file = ":auto:"|"lock_file_path"
+  **
+  ** Return or set the value of the lock_proxy_file flag.  Changing
+  ** the value sets a specific file to be used for database access locks.
+  **
+  */
+  case PragTyp_LOCK_PROXY_FILE: {
+    if( !zRight ){
+      Pager *pPager = sqlite3BtreePager(pDb->pBt);
+      char *proxy_file_path = NULL;
+      sqlite3_file *pFile = sqlite3PagerFile(pPager);
+      sqlite3OsFileControlHint(pFile, SQLITE_GET_LOCKPROXYFILE, 
+                           &proxy_file_path);
+      returnSingleText(v, "lock_proxy_file", proxy_file_path);
+    }else{
+      Pager *pPager = sqlite3BtreePager(pDb->pBt);
+      sqlite3_file *pFile = sqlite3PagerFile(pPager);
+      int res;
+      if( zRight[0] ){
+        res=sqlite3OsFileControl(pFile, SQLITE_SET_LOCKPROXYFILE, 
+                                     zRight);
+      } else {
+        res=sqlite3OsFileControl(pFile, SQLITE_SET_LOCKPROXYFILE, 
+                                     NULL);
+      }
+      if( res!=SQLITE_OK ){
+        sqlite3ErrorMsg(pParse, "failed to set lock proxy file");
+        goto pragma_out;
+      }
+    }
+    break;
+  }
+#endif /* SQLITE_ENABLE_LOCKING_STYLE */      
+    
+  /*
+  **   PRAGMA [schema.]synchronous
+  **   PRAGMA [schema.]synchronous=OFF|ON|NORMAL|FULL|EXTRA
+  **
+  ** Return or set the local value of the synchronous flag.  Changing
+  ** the local value does not make changes to the disk file and the
+  ** default value will be restored the next time the database is
+  ** opened.
+  */
+  case PragTyp_SYNCHRONOUS: {
+    if( !zRight ){
+      returnSingleInt(v, "synchronous", pDb->safety_level-1);
+    }else{
+      if( !db->autoCommit ){
+        sqlite3ErrorMsg(pParse, 
+            "Safety level may not be changed inside a transaction");
+      }else{
+        int iLevel = (getSafetyLevel(zRight,0,1)+1) & PAGER_SYNCHRONOUS_MASK;
+        if( iLevel==0 ) iLevel = 1;
+        pDb->safety_level = iLevel;
+        pDb->bSyncSet = 1;
+        setAllPagerFlags(db);
+      }
+    }
+    break;
+  }
+#endif /* SQLITE_OMIT_PAGER_PRAGMAS */
+
+#ifndef SQLITE_OMIT_FLAG_PRAGMAS
+  case PragTyp_FLAG: {
+    if( zRight==0 ){
+      returnSingleInt(v, pPragma->zName, (db->flags & pPragma->iArg)!=0 );
+    }else{
+      int mask = pPragma->iArg;    /* Mask of bits to set or clear. */
+      if( db->autoCommit==0 ){
+        /* Foreign key support may not be enabled or disabled while not
+        ** in auto-commit mode.  */
+        mask &= ~(SQLITE_ForeignKeys);
+      }
+#if SQLITE_USER_AUTHENTICATION
+      if( db->auth.authLevel==UAUTH_User ){
+        /* Do not allow non-admin users to modify the schema arbitrarily */
+        mask &= ~(SQLITE_WriteSchema);
+      }
+#endif
+
+      if( sqlite3GetBoolean(zRight, 0) ){
+        db->flags |= mask;
+      }else{
+        db->flags &= ~mask;
+        if( mask==SQLITE_DeferFKs ) db->nDeferredImmCons = 0;
+      }
+
+      /* Many of the flag-pragmas modify the code generated by the SQL 
+      ** compiler (eg. count_changes). So add an opcode to expire all
+      ** compiled SQL statements after modifying a pragma value.
+      */
+      sqlite3VdbeAddOp0(v, OP_Expire);
+      setAllPagerFlags(db);
+    }
+    break;
+  }
+#endif /* SQLITE_OMIT_FLAG_PRAGMAS */
+
+#ifndef SQLITE_OMIT_SCHEMA_PRAGMAS
+  /*
+  **   PRAGMA table_info(<table>)
+  **
+  ** Return a single row for each column of the named table. The columns of
+  ** the returned data set are:
+  **
+  ** cid:        Column id (numbered from left to right, starting at 0)
+  ** name:       Column name
+  ** type:       Column declaration type.
+  ** notnull:    True if 'NOT NULL' is part of column declaration
+  ** dflt_value: The default value for the column, if any.
+  */
+  case PragTyp_TABLE_INFO: if( zRight ){
+    Table *pTab;
+    pTab = sqlite3LocateTable(pParse, LOCATE_NOERR, zRight, zDb);
+    if( pTab ){
+      static const char *azCol[] = {
+         "cid", "name", "type", "notnull", "dflt_value", "pk"
+      };
+      int i, k;
+      int nHidden = 0;
+      Column *pCol;
+      Index *pPk = sqlite3PrimaryKeyIndex(pTab);
+      pParse->nMem = 6;
+      sqlite3CodeVerifySchema(pParse, iDb);
+      setAllColumnNames(v, 6, azCol); assert( 6==ArraySize(azCol) );
+      sqlite3ViewGetColumnNames(pParse, pTab);
+      for(i=0, pCol=pTab->aCol; i<pTab->nCol; i++, pCol++){
+        if( IsHiddenColumn(pCol) ){
+          nHidden++;
+          continue;
+        }
+        if( (pCol->colFlags & COLFLAG_PRIMKEY)==0 ){
+          k = 0;
+        }else if( pPk==0 ){
+          k = 1;
+        }else{
+          for(k=1; k<=pTab->nCol && pPk->aiColumn[k-1]!=i; k++){}
+        }
+        assert( pCol->pDflt==0 || pCol->pDflt->op==TK_SPAN );
+        sqlite3VdbeMultiLoad(v, 1, "issisi",
+               i-nHidden,
+               pCol->zName,
+               sqlite3ColumnType(pCol,""),
+               pCol->notNull ? 1 : 0,
+               pCol->pDflt ? pCol->pDflt->u.zToken : 0,
+               k);
+        sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 6);
+      }
+    }
+  }
+  break;
+
+  case PragTyp_STATS: {
+    static const char *azCol[] = { "table", "index", "width", "height" };
+    Index *pIdx;
+    HashElem *i;
+    v = sqlite3GetVdbe(pParse);
+    pParse->nMem = 4;
+    sqlite3CodeVerifySchema(pParse, iDb);
+    setAllColumnNames(v, 4, azCol);  assert( 4==ArraySize(azCol) );
+    for(i=sqliteHashFirst(&pDb->pSchema->tblHash); i; i=sqliteHashNext(i)){
+      Table *pTab = sqliteHashData(i);
+      sqlite3VdbeMultiLoad(v, 1, "ssii",
+           pTab->zName,
+           0,
+           pTab->szTabRow,
+           pTab->nRowLogEst);
+      sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 4);
+      for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+        sqlite3VdbeMultiLoad(v, 2, "sii",
+           pIdx->zName,
+           pIdx->szIdxRow,
+           pIdx->aiRowLogEst[0]);
+        sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 4);
+      }
+    }
+  }
+  break;
+
+  case PragTyp_INDEX_INFO: if( zRight ){
+    Index *pIdx;
+    Table *pTab;
+    pIdx = sqlite3FindIndex(db, zRight, zDb);
+    if( pIdx ){
+      static const char *azCol[] = {
+         "seqno", "cid", "name", "desc", "coll", "key"
+      };
+      int i;
+      int mx;
+      if( pPragma->iArg ){
+        /* PRAGMA index_xinfo (newer version with more rows and columns) */
+        mx = pIdx->nColumn;
+        pParse->nMem = 6;
+      }else{
+        /* PRAGMA index_info (legacy version) */
+        mx = pIdx->nKeyCol;
+        pParse->nMem = 3;
+      }
+      pTab = pIdx->pTable;
+      sqlite3CodeVerifySchema(pParse, iDb);
+      assert( pParse->nMem<=ArraySize(azCol) );
+      setAllColumnNames(v, pParse->nMem, azCol);
+      for(i=0; i<mx; i++){
+        i16 cnum = pIdx->aiColumn[i];
+        sqlite3VdbeMultiLoad(v, 1, "iis", i, cnum,
+                             cnum<0 ? 0 : pTab->aCol[cnum].zName);
+        if( pPragma->iArg ){
+          sqlite3VdbeMultiLoad(v, 4, "isi",
+            pIdx->aSortOrder[i],
+            pIdx->azColl[i],
+            i<pIdx->nKeyCol);
+        }
+        sqlite3VdbeAddOp2(v, OP_ResultRow, 1, pParse->nMem);
+      }
+    }
+  }
+  break;
+
+  case PragTyp_INDEX_LIST: if( zRight ){
+    Index *pIdx;
+    Table *pTab;
+    int i;
+    pTab = sqlite3FindTable(db, zRight, zDb);
+    if( pTab ){
+      static const char *azCol[] = {
+        "seq", "name", "unique", "origin", "partial"
+      };
+      v = sqlite3GetVdbe(pParse);
+      pParse->nMem = 5;
+      sqlite3CodeVerifySchema(pParse, iDb);
+      setAllColumnNames(v, 5, azCol);  assert( 5==ArraySize(azCol) );
+      for(pIdx=pTab->pIndex, i=0; pIdx; pIdx=pIdx->pNext, i++){
+        const char *azOrigin[] = { "c", "u", "pk" };
+        sqlite3VdbeMultiLoad(v, 1, "isisi",
+           i,
+           pIdx->zName,
+           IsUniqueIndex(pIdx),
+           azOrigin[pIdx->idxType],
+           pIdx->pPartIdxWhere!=0);
+        sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 5);
+      }
+    }
+  }
+  break;
+
+  case PragTyp_DATABASE_LIST: {
+    static const char *azCol[] = { "seq", "name", "file" };
+    int i;
+    pParse->nMem = 3;
+    setAllColumnNames(v, 3, azCol); assert( 3==ArraySize(azCol) );
+    for(i=0; i<db->nDb; i++){
+      if( db->aDb[i].pBt==0 ) continue;
+      assert( db->aDb[i].zDbSName!=0 );
+      sqlite3VdbeMultiLoad(v, 1, "iss",
+         i,
+         db->aDb[i].zDbSName,
+         sqlite3BtreeGetFilename(db->aDb[i].pBt));
+      sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 3);
+    }
+  }
+  break;
+
+  case PragTyp_COLLATION_LIST: {
+    static const char *azCol[] = { "seq", "name" };
+    int i = 0;
+    HashElem *p;
+    pParse->nMem = 2;
+    setAllColumnNames(v, 2, azCol); assert( 2==ArraySize(azCol) );
+    for(p=sqliteHashFirst(&db->aCollSeq); p; p=sqliteHashNext(p)){
+      CollSeq *pColl = (CollSeq *)sqliteHashData(p);
+      sqlite3VdbeMultiLoad(v, 1, "is", i++, pColl->zName);
+      sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 2);
+    }
+  }
+  break;
+#endif /* SQLITE_OMIT_SCHEMA_PRAGMAS */
+
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+  case PragTyp_FOREIGN_KEY_LIST: if( zRight ){
+    FKey *pFK;
+    Table *pTab;
+    pTab = sqlite3FindTable(db, zRight, zDb);
+    if( pTab ){
+      v = sqlite3GetVdbe(pParse);
+      pFK = pTab->pFKey;
+      if( pFK ){
+        static const char *azCol[] = {
+           "id", "seq", "table", "from", "to", "on_update", "on_delete",
+           "match"
+        };
+        int i = 0; 
+        pParse->nMem = 8;
+        sqlite3CodeVerifySchema(pParse, iDb);
+        setAllColumnNames(v, 8, azCol); assert( 8==ArraySize(azCol) );
+        while(pFK){
+          int j;
+          for(j=0; j<pFK->nCol; j++){
+            sqlite3VdbeMultiLoad(v, 1, "iissssss",
+                   i,
+                   j,
+                   pFK->zTo,
+                   pTab->aCol[pFK->aCol[j].iFrom].zName,
+                   pFK->aCol[j].zCol,
+                   actionName(pFK->aAction[1]),  /* ON UPDATE */
+                   actionName(pFK->aAction[0]),  /* ON DELETE */
+                   "NONE");
+            sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 8);
+          }
+          ++i;
+          pFK = pFK->pNextFrom;
+        }
+      }
+    }
+  }
+  break;
+#endif /* !defined(SQLITE_OMIT_FOREIGN_KEY) */
+
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+#ifndef SQLITE_OMIT_TRIGGER
+  case PragTyp_FOREIGN_KEY_CHECK: {
+    FKey *pFK;             /* A foreign key constraint */
+    Table *pTab;           /* Child table contain "REFERENCES" keyword */
+    Table *pParent;        /* Parent table that child points to */
+    Index *pIdx;           /* Index in the parent table */
+    int i;                 /* Loop counter:  Foreign key number for pTab */
+    int j;                 /* Loop counter:  Field of the foreign key */
+    HashElem *k;           /* Loop counter:  Next table in schema */
+    int x;                 /* result variable */
+    int regResult;         /* 3 registers to hold a result row */
+    int regKey;            /* Register to hold key for checking the FK */
+    int regRow;            /* Registers to hold a row from pTab */
+    int addrTop;           /* Top of a loop checking foreign keys */
+    int addrOk;            /* Jump here if the key is OK */
+    int *aiCols;           /* child to parent column mapping */
+    static const char *azCol[] = { "table", "rowid", "parent", "fkid" };
+
+    regResult = pParse->nMem+1;
+    pParse->nMem += 4;
+    regKey = ++pParse->nMem;
+    regRow = ++pParse->nMem;
+    v = sqlite3GetVdbe(pParse);
+    setAllColumnNames(v, 4, azCol); assert( 4==ArraySize(azCol) );
+    sqlite3CodeVerifySchema(pParse, iDb);
+    k = sqliteHashFirst(&db->aDb[iDb].pSchema->tblHash);
+    while( k ){
+      if( zRight ){
+        pTab = sqlite3LocateTable(pParse, 0, zRight, zDb);
+        k = 0;
+      }else{
+        pTab = (Table*)sqliteHashData(k);
+        k = sqliteHashNext(k);
+      }
+      if( pTab==0 || pTab->pFKey==0 ) continue;
+      sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
+      if( pTab->nCol+regRow>pParse->nMem ) pParse->nMem = pTab->nCol + regRow;
+      sqlite3OpenTable(pParse, 0, iDb, pTab, OP_OpenRead);
+      sqlite3VdbeLoadString(v, regResult, pTab->zName);
+      for(i=1, pFK=pTab->pFKey; pFK; i++, pFK=pFK->pNextFrom){
+        pParent = sqlite3FindTable(db, pFK->zTo, zDb);
+        if( pParent==0 ) continue;
+        pIdx = 0;
+        sqlite3TableLock(pParse, iDb, pParent->tnum, 0, pParent->zName);
+        x = sqlite3FkLocateIndex(pParse, pParent, pFK, &pIdx, 0);
+        if( x==0 ){
+          if( pIdx==0 ){
+            sqlite3OpenTable(pParse, i, iDb, pParent, OP_OpenRead);
+          }else{
+            sqlite3VdbeAddOp3(v, OP_OpenRead, i, pIdx->tnum, iDb);
+            sqlite3VdbeSetP4KeyInfo(pParse, pIdx);
+          }
+        }else{
+          k = 0;
+          break;
+        }
+      }
+      assert( pParse->nErr>0 || pFK==0 );
+      if( pFK ) break;
+      if( pParse->nTab<i ) pParse->nTab = i;
+      addrTop = sqlite3VdbeAddOp1(v, OP_Rewind, 0); VdbeCoverage(v);
+      for(i=1, pFK=pTab->pFKey; pFK; i++, pFK=pFK->pNextFrom){
+        pParent = sqlite3FindTable(db, pFK->zTo, zDb);
+        pIdx = 0;
+        aiCols = 0;
+        if( pParent ){
+          x = sqlite3FkLocateIndex(pParse, pParent, pFK, &pIdx, &aiCols);
+          assert( x==0 );
+        }
+        addrOk = sqlite3VdbeMakeLabel(v);
+        if( pParent && pIdx==0 ){
+          int iKey = pFK->aCol[0].iFrom;
+          assert( iKey>=0 && iKey<pTab->nCol );
+          if( iKey!=pTab->iPKey ){
+            sqlite3VdbeAddOp3(v, OP_Column, 0, iKey, regRow);
+            sqlite3ColumnDefault(v, pTab, iKey, regRow);
+            sqlite3VdbeAddOp2(v, OP_IsNull, regRow, addrOk); VdbeCoverage(v);
+          }else{
+            sqlite3VdbeAddOp2(v, OP_Rowid, 0, regRow);
+          }
+          sqlite3VdbeAddOp3(v, OP_SeekRowid, i, 0, regRow); VdbeCoverage(v);
+          sqlite3VdbeGoto(v, addrOk);
+          sqlite3VdbeJumpHere(v, sqlite3VdbeCurrentAddr(v)-2);
+        }else{
+          for(j=0; j<pFK->nCol; j++){
+            sqlite3ExprCodeGetColumnOfTable(v, pTab, 0,
+                            aiCols ? aiCols[j] : pFK->aCol[j].iFrom, regRow+j);
+            sqlite3VdbeAddOp2(v, OP_IsNull, regRow+j, addrOk); VdbeCoverage(v);
+          }
+          if( pParent ){
+            sqlite3VdbeAddOp4(v, OP_MakeRecord, regRow, pFK->nCol, regKey,
+                              sqlite3IndexAffinityStr(db,pIdx), pFK->nCol);
+            sqlite3VdbeAddOp4Int(v, OP_Found, i, addrOk, regKey, 0);
+            VdbeCoverage(v);
+          }
+        }
+        sqlite3VdbeAddOp2(v, OP_Rowid, 0, regResult+1);
+        sqlite3VdbeMultiLoad(v, regResult+2, "si", pFK->zTo, i-1);
+        sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, 4);
+        sqlite3VdbeResolveLabel(v, addrOk);
+        sqlite3DbFree(db, aiCols);
+      }
+      sqlite3VdbeAddOp2(v, OP_Next, 0, addrTop+1); VdbeCoverage(v);
+      sqlite3VdbeJumpHere(v, addrTop);
+    }
+  }
+  break;
+#endif /* !defined(SQLITE_OMIT_TRIGGER) */
+#endif /* !defined(SQLITE_OMIT_FOREIGN_KEY) */
+
+#ifndef NDEBUG
+  case PragTyp_PARSER_TRACE: {
+    if( zRight ){
+      if( sqlite3GetBoolean(zRight, 0) ){
+        sqlite3ParserTrace(stdout, "parser: ");
+      }else{
+        sqlite3ParserTrace(0, 0);
+      }
+    }
+  }
+  break;
+#endif
+
+  /* Reinstall the LIKE and GLOB functions.  The variant of LIKE
+  ** used will be case sensitive or not depending on the RHS.
+  */
+  case PragTyp_CASE_SENSITIVE_LIKE: {
+    if( zRight ){
+      sqlite3RegisterLikeFunctions(db, sqlite3GetBoolean(zRight, 0));
+    }
+  }
+  break;
+
+#ifndef SQLITE_INTEGRITY_CHECK_ERROR_MAX
+# define SQLITE_INTEGRITY_CHECK_ERROR_MAX 100
+#endif
+
+#ifndef SQLITE_OMIT_INTEGRITY_CHECK
+  /* Pragma "quick_check" is reduced version of 
+  ** integrity_check designed to detect most database corruption
+  ** without most of the overhead of a full integrity-check.
+  */
+  case PragTyp_INTEGRITY_CHECK: {
+    int i, j, addr, mxErr;
+
+    int isQuick = (sqlite3Tolower(zLeft[0])=='q');
+
+    /* If the PRAGMA command was of the form "PRAGMA <db>.integrity_check",
+    ** then iDb is set to the index of the database identified by <db>.
+    ** In this case, the integrity of database iDb only is verified by
+    ** the VDBE created below.
+    **
+    ** Otherwise, if the command was simply "PRAGMA integrity_check" (or
+    ** "PRAGMA quick_check"), then iDb is set to 0. In this case, set iDb
+    ** to -1 here, to indicate that the VDBE should verify the integrity
+    ** of all attached databases.  */
+    assert( iDb>=0 );
+    assert( iDb==0 || pId2->z );
+    if( pId2->z==0 ) iDb = -1;
+
+    /* Initialize the VDBE program */
+    pParse->nMem = 6;
+    setOneColumnName(v, "integrity_check");
+
+    /* Set the maximum error count */
+    mxErr = SQLITE_INTEGRITY_CHECK_ERROR_MAX;
+    if( zRight ){
+      sqlite3GetInt32(zRight, &mxErr);
+      if( mxErr<=0 ){
+        mxErr = SQLITE_INTEGRITY_CHECK_ERROR_MAX;
+      }
+    }
+    sqlite3VdbeAddOp2(v, OP_Integer, mxErr, 1);  /* reg[1] holds errors left */
+
+    /* Do an integrity check on each database file */
+    for(i=0; i<db->nDb; i++){
+      HashElem *x;
+      Hash *pTbls;
+      int *aRoot;
+      int cnt = 0;
+      int mxIdx = 0;
+      int nIdx;
+
+      if( OMIT_TEMPDB && i==1 ) continue;
+      if( iDb>=0 && i!=iDb ) continue;
+
+      sqlite3CodeVerifySchema(pParse, i);
+      addr = sqlite3VdbeAddOp1(v, OP_IfPos, 1); /* Halt if out of errors */
+      VdbeCoverage(v);
+      sqlite3VdbeAddOp2(v, OP_Halt, 0, 0);
+      sqlite3VdbeJumpHere(v, addr);
+
+      /* Do an integrity check of the B-Tree
+      **
+      ** Begin by finding the root pages numbers
+      ** for all tables and indices in the database.
+      */
+      assert( sqlite3SchemaMutexHeld(db, i, 0) );
+      pTbls = &db->aDb[i].pSchema->tblHash;
+      for(cnt=0, x=sqliteHashFirst(pTbls); x; x=sqliteHashNext(x)){
+        Table *pTab = sqliteHashData(x);
+        Index *pIdx;
+        if( HasRowid(pTab) ) cnt++;
+        for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdx++){ cnt++; }
+        if( nIdx>mxIdx ) mxIdx = nIdx;
+      }
+      aRoot = sqlite3DbMallocRawNN(db, sizeof(int)*(cnt+1));
+      if( aRoot==0 ) break;
+      for(cnt=0, x=sqliteHashFirst(pTbls); x; x=sqliteHashNext(x)){
+        Table *pTab = sqliteHashData(x);
+        Index *pIdx;
+        if( HasRowid(pTab) ) aRoot[cnt++] = pTab->tnum;
+        for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+          aRoot[cnt++] = pIdx->tnum;
+        }
+      }
+      aRoot[cnt] = 0;
+
+      /* Make sure sufficient number of registers have been allocated */
+      pParse->nMem = MAX( pParse->nMem, 8+mxIdx );
+
+      /* Do the b-tree integrity checks */
+      sqlite3VdbeAddOp4(v, OP_IntegrityCk, 2, cnt, 1, (char*)aRoot,P4_INTARRAY);
+      sqlite3VdbeChangeP5(v, (u8)i);
+      addr = sqlite3VdbeAddOp1(v, OP_IsNull, 2); VdbeCoverage(v);
+      sqlite3VdbeAddOp4(v, OP_String8, 0, 3, 0,
+         sqlite3MPrintf(db, "*** in database %s ***\n", db->aDb[i].zDbSName),
+         P4_DYNAMIC);
+      sqlite3VdbeAddOp3(v, OP_Move, 2, 4, 1);
+      sqlite3VdbeAddOp3(v, OP_Concat, 4, 3, 2);
+      sqlite3VdbeAddOp2(v, OP_ResultRow, 2, 1);
+      sqlite3VdbeJumpHere(v, addr);
+
+      /* Make sure all the indices are constructed correctly.
+      */
+      for(x=sqliteHashFirst(pTbls); x && !isQuick; x=sqliteHashNext(x)){
+        Table *pTab = sqliteHashData(x);
+        Index *pIdx, *pPk;
+        Index *pPrior = 0;
+        int loopTop;
+        int iDataCur, iIdxCur;
+        int r1 = -1;
+
+        if( pTab->pIndex==0 ) continue;
+        pPk = HasRowid(pTab) ? 0 : sqlite3PrimaryKeyIndex(pTab);
+        addr = sqlite3VdbeAddOp1(v, OP_IfPos, 1);  /* Stop if out of errors */
+        VdbeCoverage(v);
+        sqlite3VdbeAddOp2(v, OP_Halt, 0, 0);
+        sqlite3VdbeJumpHere(v, addr);
+        sqlite3ExprCacheClear(pParse);
+        sqlite3OpenTableAndIndices(pParse, pTab, OP_OpenRead, 0,
+                                   1, 0, &iDataCur, &iIdxCur);
+        sqlite3VdbeAddOp2(v, OP_Integer, 0, 7);
+        for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
+          sqlite3VdbeAddOp2(v, OP_Integer, 0, 8+j); /* index entries counter */
+        }
+        assert( pParse->nMem>=8+j );
+        assert( sqlite3NoTempsInRange(pParse,1,7+j) );
+        sqlite3VdbeAddOp2(v, OP_Rewind, iDataCur, 0); VdbeCoverage(v);
+        loopTop = sqlite3VdbeAddOp2(v, OP_AddImm, 7, 1);
+        /* Verify that all NOT NULL columns really are NOT NULL */
+        for(j=0; j<pTab->nCol; j++){
+          char *zErr;
+          int jmp2, jmp3;
+          if( j==pTab->iPKey ) continue;
+          if( pTab->aCol[j].notNull==0 ) continue;
+          sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, j, 3);
+          sqlite3VdbeChangeP5(v, OPFLAG_TYPEOFARG);
+          jmp2 = sqlite3VdbeAddOp1(v, OP_NotNull, 3); VdbeCoverage(v);
+          sqlite3VdbeAddOp2(v, OP_AddImm, 1, -1); /* Decrement error limit */
+          zErr = sqlite3MPrintf(db, "NULL value in %s.%s", pTab->zName,
+                              pTab->aCol[j].zName);
+          sqlite3VdbeAddOp4(v, OP_String8, 0, 3, 0, zErr, P4_DYNAMIC);
+          sqlite3VdbeAddOp2(v, OP_ResultRow, 3, 1);
+          jmp3 = sqlite3VdbeAddOp1(v, OP_IfPos, 1); VdbeCoverage(v);
+          sqlite3VdbeAddOp0(v, OP_Halt);
+          sqlite3VdbeJumpHere(v, jmp2);
+          sqlite3VdbeJumpHere(v, jmp3);
+        }
+        /* Validate index entries for the current row */
+        for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
+          int jmp2, jmp3, jmp4, jmp5;
+          int ckUniq = sqlite3VdbeMakeLabel(v);
+          if( pPk==pIdx ) continue;
+          r1 = sqlite3GenerateIndexKey(pParse, pIdx, iDataCur, 0, 0, &jmp3,
+                                       pPrior, r1);
+          pPrior = pIdx;
+          sqlite3VdbeAddOp2(v, OP_AddImm, 8+j, 1);  /* increment entry count */
+          /* Verify that an index entry exists for the current table row */
+          jmp2 = sqlite3VdbeAddOp4Int(v, OP_Found, iIdxCur+j, ckUniq, r1,
+                                      pIdx->nColumn); VdbeCoverage(v);
+          sqlite3VdbeAddOp2(v, OP_AddImm, 1, -1); /* Decrement error limit */
+          sqlite3VdbeLoadString(v, 3, "row ");
+          sqlite3VdbeAddOp3(v, OP_Concat, 7, 3, 3);
+          sqlite3VdbeLoadString(v, 4, " missing from index ");
+          sqlite3VdbeAddOp3(v, OP_Concat, 4, 3, 3);
+          jmp5 = sqlite3VdbeLoadString(v, 4, pIdx->zName);
+          sqlite3VdbeAddOp3(v, OP_Concat, 4, 3, 3);
+          sqlite3VdbeAddOp2(v, OP_ResultRow, 3, 1);
+          jmp4 = sqlite3VdbeAddOp1(v, OP_IfPos, 1); VdbeCoverage(v);
+          sqlite3VdbeAddOp0(v, OP_Halt);
+          sqlite3VdbeJumpHere(v, jmp2);
+          /* For UNIQUE indexes, verify that only one entry exists with the
+          ** current key.  The entry is unique if (1) any column is NULL
+          ** or (2) the next entry has a different key */
+          if( IsUniqueIndex(pIdx) ){
+            int uniqOk = sqlite3VdbeMakeLabel(v);
+            int jmp6;
+            int kk;
+            for(kk=0; kk<pIdx->nKeyCol; kk++){
+              int iCol = pIdx->aiColumn[kk];
+              assert( iCol!=XN_ROWID && iCol<pTab->nCol );
+              if( iCol>=0 && pTab->aCol[iCol].notNull ) continue;
+              sqlite3VdbeAddOp2(v, OP_IsNull, r1+kk, uniqOk);
+              VdbeCoverage(v);
+            }
+            jmp6 = sqlite3VdbeAddOp1(v, OP_Next, iIdxCur+j); VdbeCoverage(v);
+            sqlite3VdbeGoto(v, uniqOk);
+            sqlite3VdbeJumpHere(v, jmp6);
+            sqlite3VdbeAddOp4Int(v, OP_IdxGT, iIdxCur+j, uniqOk, r1,
+                                 pIdx->nKeyCol); VdbeCoverage(v);
+            sqlite3VdbeAddOp2(v, OP_AddImm, 1, -1); /* Decrement error limit */
+            sqlite3VdbeLoadString(v, 3, "non-unique entry in index ");
+            sqlite3VdbeGoto(v, jmp5);
+            sqlite3VdbeResolveLabel(v, uniqOk);
+          }
+          sqlite3VdbeJumpHere(v, jmp4);
+          sqlite3ResolvePartIdxLabel(pParse, jmp3);
+        }
+        sqlite3VdbeAddOp2(v, OP_Next, iDataCur, loopTop); VdbeCoverage(v);
+        sqlite3VdbeJumpHere(v, loopTop-1);
+#ifndef SQLITE_OMIT_BTREECOUNT
+        sqlite3VdbeLoadString(v, 2, "wrong # of entries in index ");
+        for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
+          if( pPk==pIdx ) continue;
+          addr = sqlite3VdbeCurrentAddr(v);
+          sqlite3VdbeAddOp2(v, OP_IfPos, 1, addr+2); VdbeCoverage(v);
+          sqlite3VdbeAddOp2(v, OP_Halt, 0, 0);
+          sqlite3VdbeAddOp2(v, OP_Count, iIdxCur+j, 3);
+          sqlite3VdbeAddOp3(v, OP_Eq, 8+j, addr+8, 3); VdbeCoverage(v);
+          sqlite3VdbeChangeP5(v, SQLITE_NOTNULL);
+          sqlite3VdbeAddOp2(v, OP_AddImm, 1, -1);
+          sqlite3VdbeLoadString(v, 3, pIdx->zName);
+          sqlite3VdbeAddOp3(v, OP_Concat, 3, 2, 7);
+          sqlite3VdbeAddOp2(v, OP_ResultRow, 7, 1);
+        }
+#endif /* SQLITE_OMIT_BTREECOUNT */
+      } 
+    }
+    {
+      static const int iLn = VDBE_OFFSET_LINENO(2);
+      static const VdbeOpList endCode[] = {
+        { OP_AddImm,      1, 0,        0},    /* 0 */
+        { OP_If,          1, 4,        0},    /* 1 */
+        { OP_String8,     0, 3,        0},    /* 2 */
+        { OP_ResultRow,   3, 1,        0},    /* 3 */
+      };
+      VdbeOp *aOp;
+
+      aOp = sqlite3VdbeAddOpList(v, ArraySize(endCode), endCode, iLn);
+      if( aOp ){
+        aOp[0].p2 = -mxErr;
+        aOp[2].p4type = P4_STATIC;
+        aOp[2].p4.z = "ok";
+      }
+    }
+  }
+  break;
+#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
+
+#ifndef SQLITE_OMIT_UTF16
+  /*
+  **   PRAGMA encoding
+  **   PRAGMA encoding = "utf-8"|"utf-16"|"utf-16le"|"utf-16be"
+  **
+  ** In its first form, this pragma returns the encoding of the main
+  ** database. If the database is not initialized, it is initialized now.
+  **
+  ** The second form of this pragma is a no-op if the main database file
+  ** has not already been initialized. In this case it sets the default
+  ** encoding that will be used for the main database file if a new file
+  ** is created. If an existing main database file is opened, then the
+  ** default text encoding for the existing database is used.
+  ** 
+  ** In all cases new databases created using the ATTACH command are
+  ** created to use the same default text encoding as the main database. If
+  ** the main database has not been initialized and/or created when ATTACH
+  ** is executed, this is done before the ATTACH operation.
+  **
+  ** In the second form this pragma sets the text encoding to be used in
+  ** new database files created using this database handle. It is only
+  ** useful if invoked immediately after the main database i
+  */
+  case PragTyp_ENCODING: {
+    static const struct EncName {
+      char *zName;
+      u8 enc;
+    } encnames[] = {
+      { "UTF8",     SQLITE_UTF8        },
+      { "UTF-8",    SQLITE_UTF8        },  /* Must be element [1] */
+      { "UTF-16le", SQLITE_UTF16LE     },  /* Must be element [2] */
+      { "UTF-16be", SQLITE_UTF16BE     },  /* Must be element [3] */
+      { "UTF16le",  SQLITE_UTF16LE     },
+      { "UTF16be",  SQLITE_UTF16BE     },
+      { "UTF-16",   0                  }, /* SQLITE_UTF16NATIVE */
+      { "UTF16",    0                  }, /* SQLITE_UTF16NATIVE */
+      { 0, 0 }
+    };
+    const struct EncName *pEnc;
+    if( !zRight ){    /* "PRAGMA encoding" */
+      if( sqlite3ReadSchema(pParse) ) goto pragma_out;
+      assert( encnames[SQLITE_UTF8].enc==SQLITE_UTF8 );
+      assert( encnames[SQLITE_UTF16LE].enc==SQLITE_UTF16LE );
+      assert( encnames[SQLITE_UTF16BE].enc==SQLITE_UTF16BE );
+      returnSingleText(v, "encoding", encnames[ENC(pParse->db)].zName);
+    }else{                        /* "PRAGMA encoding = XXX" */
+      /* Only change the value of sqlite.enc if the database handle is not
+      ** initialized. If the main database exists, the new sqlite.enc value
+      ** will be overwritten when the schema is next loaded. If it does not
+      ** already exists, it will be created to use the new encoding value.
+      */
+      if( 
+        !(DbHasProperty(db, 0, DB_SchemaLoaded)) || 
+        DbHasProperty(db, 0, DB_Empty) 
+      ){
+        for(pEnc=&encnames[0]; pEnc->zName; pEnc++){
+          if( 0==sqlite3StrICmp(zRight, pEnc->zName) ){
+            SCHEMA_ENC(db) = ENC(db) =
+                pEnc->enc ? pEnc->enc : SQLITE_UTF16NATIVE;
+            break;
+          }
+        }
+        if( !pEnc->zName ){
+          sqlite3ErrorMsg(pParse, "unsupported encoding: %s", zRight);
+        }
+      }
+    }
+  }
+  break;
+#endif /* SQLITE_OMIT_UTF16 */
+
+#ifndef SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS
+  /*
+  **   PRAGMA [schema.]schema_version
+  **   PRAGMA [schema.]schema_version = <integer>
+  **
+  **   PRAGMA [schema.]user_version
+  **   PRAGMA [schema.]user_version = <integer>
+  **
+  **   PRAGMA [schema.]freelist_count
+  **
+  **   PRAGMA [schema.]data_version
+  **
+  **   PRAGMA [schema.]application_id
+  **   PRAGMA [schema.]application_id = <integer>
+  **
+  ** The pragma's schema_version and user_version are used to set or get
+  ** the value of the schema-version and user-version, respectively. Both
+  ** the schema-version and the user-version are 32-bit signed integers
+  ** stored in the database header.
+  **
+  ** The schema-cookie is usually only manipulated internally by SQLite. It
+  ** is incremented by SQLite whenever the database schema is modified (by
+  ** creating or dropping a table or index). The schema version is used by
+  ** SQLite each time a query is executed to ensure that the internal cache
+  ** of the schema used when compiling the SQL query matches the schema of
+  ** the database against which the compiled query is actually executed.
+  ** Subverting this mechanism by using "PRAGMA schema_version" to modify
+  ** the schema-version is potentially dangerous and may lead to program
+  ** crashes or database corruption. Use with caution!
+  **
+  ** The user-version is not used internally by SQLite. It may be used by
+  ** applications for any purpose.
+  */
+  case PragTyp_HEADER_VALUE: {
+    int iCookie = pPragma->iArg;  /* Which cookie to read or write */
+    sqlite3VdbeUsesBtree(v, iDb);
+    if( zRight && (pPragma->mPragFlag & PragFlag_ReadOnly)==0 ){
+      /* Write the specified cookie value */
+      static const VdbeOpList setCookie[] = {
+        { OP_Transaction,    0,  1,  0},    /* 0 */
+        { OP_SetCookie,      0,  0,  0},    /* 1 */
+      };
+      VdbeOp *aOp;
+      sqlite3VdbeVerifyNoMallocRequired(v, ArraySize(setCookie));
+      aOp = sqlite3VdbeAddOpList(v, ArraySize(setCookie), setCookie, 0);
+      if( ONLY_IF_REALLOC_STRESS(aOp==0) ) break;
+      aOp[0].p1 = iDb;
+      aOp[1].p1 = iDb;
+      aOp[1].p2 = iCookie;
+      aOp[1].p3 = sqlite3Atoi(zRight);
+    }else{
+      /* Read the specified cookie value */
+      static const VdbeOpList readCookie[] = {
+        { OP_Transaction,     0,  0,  0},    /* 0 */
+        { OP_ReadCookie,      0,  1,  0},    /* 1 */
+        { OP_ResultRow,       1,  1,  0}
+      };
+      VdbeOp *aOp;
+      sqlite3VdbeVerifyNoMallocRequired(v, ArraySize(readCookie));
+      aOp = sqlite3VdbeAddOpList(v, ArraySize(readCookie),readCookie,0);
+      if( ONLY_IF_REALLOC_STRESS(aOp==0) ) break;
+      aOp[0].p1 = iDb;
+      aOp[1].p1 = iDb;
+      aOp[1].p3 = iCookie;
+      sqlite3VdbeSetNumCols(v, 1);
+      sqlite3VdbeSetColName(v, 0, COLNAME_NAME, zLeft, SQLITE_TRANSIENT);
+      sqlite3VdbeReusable(v);
+    }
+  }
+  break;
+#endif /* SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS */
+
+#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
+  /*
+  **   PRAGMA compile_options
+  **
+  ** Return the names of all compile-time options used in this build,
+  ** one option per row.
+  */
+  case PragTyp_COMPILE_OPTIONS: {
+    int i = 0;
+    const char *zOpt;
+    pParse->nMem = 1;
+    setOneColumnName(v, "compile_option");
+    while( (zOpt = sqlite3_compileoption_get(i++))!=0 ){
+      sqlite3VdbeLoadString(v, 1, zOpt);
+      sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 1);
+    }
+    sqlite3VdbeReusable(v);
+  }
+  break;
+#endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */
+
+#ifndef SQLITE_OMIT_WAL
+  /*
+  **   PRAGMA [schema.]wal_checkpoint = passive|full|restart|truncate
+  **
+  ** Checkpoint the database.
+  */
+  case PragTyp_WAL_CHECKPOINT: {
+    static const char *azCol[] = { "busy", "log", "checkpointed" };
+    int iBt = (pId2->z?iDb:SQLITE_MAX_ATTACHED);
+    int eMode = SQLITE_CHECKPOINT_PASSIVE;
+    if( zRight ){
+      if( sqlite3StrICmp(zRight, "full")==0 ){
+        eMode = SQLITE_CHECKPOINT_FULL;
+      }else if( sqlite3StrICmp(zRight, "restart")==0 ){
+        eMode = SQLITE_CHECKPOINT_RESTART;
+      }else if( sqlite3StrICmp(zRight, "truncate")==0 ){
+        eMode = SQLITE_CHECKPOINT_TRUNCATE;
+      }
+    }
+    setAllColumnNames(v, 3, azCol);  assert( 3==ArraySize(azCol) );
+    pParse->nMem = 3;
+    sqlite3VdbeAddOp3(v, OP_Checkpoint, iBt, eMode, 1);
+    sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 3);
+  }
+  break;
+
+  /*
+  **   PRAGMA wal_autocheckpoint
+  **   PRAGMA wal_autocheckpoint = N
+  **
+  ** Configure a database connection to automatically checkpoint a database
+  ** after accumulating N frames in the log. Or query for the current value
+  ** of N.
+  */
+  case PragTyp_WAL_AUTOCHECKPOINT: {
+    if( zRight ){
+      sqlite3_wal_autocheckpoint(db, sqlite3Atoi(zRight));
+    }
+    returnSingleInt(v, "wal_autocheckpoint", 
+       db->xWalCallback==sqlite3WalDefaultHook ? 
+           SQLITE_PTR_TO_INT(db->pWalArg) : 0);
+  }
+  break;
+#endif
+
+  /*
+  **  PRAGMA shrink_memory
+  **
+  ** IMPLEMENTATION-OF: R-23445-46109 This pragma causes the database
+  ** connection on which it is invoked to free up as much memory as it
+  ** can, by calling sqlite3_db_release_memory().
+  */
+  case PragTyp_SHRINK_MEMORY: {
+    sqlite3_db_release_memory(db);
+    break;
+  }
+
+  /*
+  **   PRAGMA busy_timeout
+  **   PRAGMA busy_timeout = N
+  **
+  ** Call sqlite3_busy_timeout(db, N).  Return the current timeout value
+  ** if one is set.  If no busy handler or a different busy handler is set
+  ** then 0 is returned.  Setting the busy_timeout to 0 or negative
+  ** disables the timeout.
+  */
+  /*case PragTyp_BUSY_TIMEOUT*/ default: {
+    assert( pPragma->ePragTyp==PragTyp_BUSY_TIMEOUT );
+    if( zRight ){
+      sqlite3_busy_timeout(db, sqlite3Atoi(zRight));
+    }
+    returnSingleInt(v, "timeout",  db->busyTimeout);
+    break;
+  }
+
+  /*
+  **   PRAGMA soft_heap_limit
+  **   PRAGMA soft_heap_limit = N
+  **
+  ** IMPLEMENTATION-OF: R-26343-45930 This pragma invokes the
+  ** sqlite3_soft_heap_limit64() interface with the argument N, if N is
+  ** specified and is a non-negative integer.
+  ** IMPLEMENTATION-OF: R-64451-07163 The soft_heap_limit pragma always
+  ** returns the same integer that would be returned by the
+  ** sqlite3_soft_heap_limit64(-1) C-language function.
+  */
+  case PragTyp_SOFT_HEAP_LIMIT: {
+    sqlite3_int64 N;
+    if( zRight && sqlite3DecOrHexToI64(zRight, &N)==SQLITE_OK ){
+      sqlite3_soft_heap_limit64(N);
+    }
+    returnSingleInt(v, "soft_heap_limit",  sqlite3_soft_heap_limit64(-1));
+    break;
+  }
+
+  /*
+  **   PRAGMA threads
+  **   PRAGMA threads = N
+  **
+  ** Configure the maximum number of worker threads.  Return the new
+  ** maximum, which might be less than requested.
+  */
+  case PragTyp_THREADS: {
+    sqlite3_int64 N;
+    if( zRight
+     && sqlite3DecOrHexToI64(zRight, &N)==SQLITE_OK
+     && N>=0
+    ){
+      sqlite3_limit(db, SQLITE_LIMIT_WORKER_THREADS, (int)(N&0x7fffffff));
+    }
+    returnSingleInt(v, "threads",
+                    sqlite3_limit(db, SQLITE_LIMIT_WORKER_THREADS, -1));
+    break;
+  }
+
+#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
+  /*
+  ** Report the current state of file logs for all databases
+  */
+  case PragTyp_LOCK_STATUS: {
+    static const char *const azLockName[] = {
+      "unlocked", "shared", "reserved", "pending", "exclusive"
+    };
+    static const char *azCol[] = { "database", "status" };
+    int i;
+    setAllColumnNames(v, 2, azCol); assert( 2==ArraySize(azCol) );
+    pParse->nMem = 2;
+    for(i=0; i<db->nDb; i++){
+      Btree *pBt;
+      const char *zState = "unknown";
+      int j;
+      if( db->aDb[i].zDbSName==0 ) continue;
+      pBt = db->aDb[i].pBt;
+      if( pBt==0 || sqlite3BtreePager(pBt)==0 ){
+        zState = "closed";
+      }else if( sqlite3_file_control(db, i ? db->aDb[i].zDbSName : 0, 
+                                     SQLITE_FCNTL_LOCKSTATE, &j)==SQLITE_OK ){
+         zState = azLockName[j];
+      }
+      sqlite3VdbeMultiLoad(v, 1, "ss", db->aDb[i].zDbSName, zState);
+      sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 2);
+    }
+    break;
+  }
+#endif
+
+#ifdef SQLITE_HAS_CODEC
+  case PragTyp_KEY: {
+    if( zRight ) sqlite3_key_v2(db, zDb, zRight, sqlite3Strlen30(zRight));
+    break;
+  }
+  case PragTyp_REKEY: {
+    if( zRight ) sqlite3_rekey_v2(db, zDb, zRight, sqlite3Strlen30(zRight));
+    break;
+  }
+  case PragTyp_HEXKEY: {
+    if( zRight ){
+      u8 iByte;
+      int i;
+      char zKey[40];
+      for(i=0, iByte=0; i<sizeof(zKey)*2 && sqlite3Isxdigit(zRight[i]); i++){
+        iByte = (iByte<<4) + sqlite3HexToInt(zRight[i]);
+        if( (i&1)!=0 ) zKey[i/2] = iByte;
+      }
+      if( (zLeft[3] & 0xf)==0xb ){
+        sqlite3_key_v2(db, zDb, zKey, i/2);
+      }else{
+        sqlite3_rekey_v2(db, zDb, zKey, i/2);
+      }
+    }
+    break;
+  }
+#endif
+#if defined(SQLITE_HAS_CODEC) || defined(SQLITE_ENABLE_CEROD)
+  case PragTyp_ACTIVATE_EXTENSIONS: if( zRight ){
+#ifdef SQLITE_HAS_CODEC
+    if( sqlite3StrNICmp(zRight, "see-", 4)==0 ){
+      sqlite3_activate_see(&zRight[4]);
+    }
+#endif
+#ifdef SQLITE_ENABLE_CEROD
+    if( sqlite3StrNICmp(zRight, "cerod-", 6)==0 ){
+      sqlite3_activate_cerod(&zRight[6]);
+    }
+#endif
+  }
+  break;
+#endif
+
+  } /* End of the PRAGMA switch */
+
+pragma_out:
+  sqlite3DbFree(db, zLeft);
+  sqlite3DbFree(db, zRight);
+}
+
+#endif /* SQLITE_OMIT_PRAGMA */
+
+/************** End of pragma.c **********************************************/
+/************** Begin file prepare.c *****************************************/
+/*
+** 2005 May 25
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the implementation of the sqlite3_prepare()
+** interface, and routines that contribute to loading the database schema
+** from disk.
+*/
+/* #include "sqliteInt.h" */
+
+/*
+** Fill the InitData structure with an error message that indicates
+** that the database is corrupt.
+*/
+static void corruptSchema(
+  InitData *pData,     /* Initialization context */
+  const char *zObj,    /* Object being parsed at the point of error */
+  const char *zExtra   /* Error information */
+){
+  sqlite3 *db = pData->db;
+  if( !db->mallocFailed && (db->flags & SQLITE_RecoveryMode)==0 ){
+    char *z;
+    if( zObj==0 ) zObj = "?";
+    z = sqlite3MPrintf(db, "malformed database schema (%s)", zObj);
+    if( zExtra ) z = sqlite3MPrintf(db, "%z - %s", z, zExtra);
+    sqlite3DbFree(db, *pData->pzErrMsg);
+    *pData->pzErrMsg = z;
+  }
+  pData->rc = db->mallocFailed ? SQLITE_NOMEM_BKPT : SQLITE_CORRUPT_BKPT;
+}
+
+/*
+** This is the callback routine for the code that initializes the
+** database.  See sqlite3Init() below for additional information.
+** This routine is also called from the OP_ParseSchema opcode of the VDBE.
+**
+** Each callback contains the following information:
+**
+**     argv[0] = name of thing being created
+**     argv[1] = root page number for table or index. 0 for trigger or view.
+**     argv[2] = SQL text for the CREATE statement.
+**
+*/
+SQLITE_PRIVATE int sqlite3InitCallback(void *pInit, int argc, char **argv, char **NotUsed){
+  InitData *pData = (InitData*)pInit;
+  sqlite3 *db = pData->db;
+  int iDb = pData->iDb;
+
+  assert( argc==3 );
+  UNUSED_PARAMETER2(NotUsed, argc);
+  assert( sqlite3_mutex_held(db->mutex) );
+  DbClearProperty(db, iDb, DB_Empty);
+  if( db->mallocFailed ){
+    corruptSchema(pData, argv[0], 0);
+    return 1;
+  }
+
+  assert( iDb>=0 && iDb<db->nDb );
+  if( argv==0 ) return 0;   /* Might happen if EMPTY_RESULT_CALLBACKS are on */
+  if( argv[1]==0 ){
+    corruptSchema(pData, argv[0], 0);
+  }else if( sqlite3_strnicmp(argv[2],"create ",7)==0 ){
+    /* Call the parser to process a CREATE TABLE, INDEX or VIEW.
+    ** But because db->init.busy is set to 1, no VDBE code is generated
+    ** or executed.  All the parser does is build the internal data
+    ** structures that describe the table, index, or view.
+    */
+    int rc;
+    u8 saved_iDb = db->init.iDb;
+    sqlite3_stmt *pStmt;
+    TESTONLY(int rcp);            /* Return code from sqlite3_prepare() */
+
+    assert( db->init.busy );
+    db->init.iDb = iDb;
+    db->init.newTnum = sqlite3Atoi(argv[1]);
+    db->init.orphanTrigger = 0;
+    TESTONLY(rcp = ) sqlite3_prepare(db, argv[2], -1, &pStmt, 0);
+    rc = db->errCode;
+    assert( (rc&0xFF)==(rcp&0xFF) );
+    db->init.iDb = saved_iDb;
+    assert( saved_iDb==0 || (db->flags & SQLITE_Vacuum)!=0 );
+    if( SQLITE_OK!=rc ){
+      if( db->init.orphanTrigger ){
+        assert( iDb==1 );
+      }else{
+        pData->rc = rc;
+        if( rc==SQLITE_NOMEM ){
+          sqlite3OomFault(db);
+        }else if( rc!=SQLITE_INTERRUPT && (rc&0xFF)!=SQLITE_LOCKED ){
+          corruptSchema(pData, argv[0], sqlite3_errmsg(db));
+        }
+      }
+    }
+    sqlite3_finalize(pStmt);
+  }else if( argv[0]==0 || (argv[2]!=0 && argv[2][0]!=0) ){
+    corruptSchema(pData, argv[0], 0);
+  }else{
+    /* If the SQL column is blank it means this is an index that
+    ** was created to be the PRIMARY KEY or to fulfill a UNIQUE
+    ** constraint for a CREATE TABLE.  The index should have already
+    ** been created when we processed the CREATE TABLE.  All we have
+    ** to do here is record the root page number for that index.
+    */
+    Index *pIndex;
+    pIndex = sqlite3FindIndex(db, argv[0], db->aDb[iDb].zDbSName);
+    if( pIndex==0 ){
+      /* This can occur if there exists an index on a TEMP table which
+      ** has the same name as another index on a permanent index.  Since
+      ** the permanent table is hidden by the TEMP table, we can also
+      ** safely ignore the index on the permanent table.
+      */
+      /* Do Nothing */;
+    }else if( sqlite3GetInt32(argv[1], &pIndex->tnum)==0 ){
+      corruptSchema(pData, argv[0], "invalid rootpage");
+    }
+  }
+  return 0;
+}
+
+/*
+** Attempt to read the database schema and initialize internal
+** data structures for a single database file.  The index of the
+** database file is given by iDb.  iDb==0 is used for the main
+** database.  iDb==1 should never be used.  iDb>=2 is used for
+** auxiliary databases.  Return one of the SQLITE_ error codes to
+** indicate success or failure.
+*/
+static int sqlite3InitOne(sqlite3 *db, int iDb, char **pzErrMsg){
+  int rc;
+  int i;
+#ifndef SQLITE_OMIT_DEPRECATED
+  int size;
+#endif
+  Db *pDb;
+  char const *azArg[4];
+  int meta[5];
+  InitData initData;
+  const char *zMasterName;
+  int openedTransaction = 0;
+
+  assert( iDb>=0 && iDb<db->nDb );
+  assert( db->aDb[iDb].pSchema );
+  assert( sqlite3_mutex_held(db->mutex) );
+  assert( iDb==1 || sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) );
+
+  /* Construct the in-memory representation schema tables (sqlite_master or
+  ** sqlite_temp_master) by invoking the parser directly.  The appropriate
+  ** table name will be inserted automatically by the parser so we can just
+  ** use the abbreviation "x" here.  The parser will also automatically tag
+  ** the schema table as read-only. */
+  azArg[0] = zMasterName = SCHEMA_TABLE(iDb);
+  azArg[1] = "1";
+  azArg[2] = "CREATE TABLE x(type text,name text,tbl_name text,"
+                            "rootpage integer,sql text)";
+  azArg[3] = 0;
+  initData.db = db;
+  initData.iDb = iDb;
+  initData.rc = SQLITE_OK;
+  initData.pzErrMsg = pzErrMsg;
+  sqlite3InitCallback(&initData, 3, (char **)azArg, 0);
+  if( initData.rc ){
+    rc = initData.rc;
+    goto error_out;
+  }
+
+  /* Create a cursor to hold the database open
+  */
+  pDb = &db->aDb[iDb];
+  if( pDb->pBt==0 ){
+    if( !OMIT_TEMPDB && ALWAYS(iDb==1) ){
+      DbSetProperty(db, 1, DB_SchemaLoaded);
+    }
+    return SQLITE_OK;
+  }
+
+  /* If there is not already a read-only (or read-write) transaction opened
+  ** on the b-tree database, open one now. If a transaction is opened, it 
+  ** will be closed before this function returns.  */
+  sqlite3BtreeEnter(pDb->pBt);
+  if( !sqlite3BtreeIsInReadTrans(pDb->pBt) ){
+    rc = sqlite3BtreeBeginTrans(pDb->pBt, 0);
+    if( rc!=SQLITE_OK ){
+      sqlite3SetString(pzErrMsg, db, sqlite3ErrStr(rc));
+      goto initone_error_out;
+    }
+    openedTransaction = 1;
+  }
+
+  /* Get the database meta information.
+  **
+  ** Meta values are as follows:
+  **    meta[0]   Schema cookie.  Changes with each schema change.
+  **    meta[1]   File format of schema layer.
+  **    meta[2]   Size of the page cache.
+  **    meta[3]   Largest rootpage (auto/incr_vacuum mode)
+  **    meta[4]   Db text encoding. 1:UTF-8 2:UTF-16LE 3:UTF-16BE
+  **    meta[5]   User version
+  **    meta[6]   Incremental vacuum mode
+  **    meta[7]   unused
+  **    meta[8]   unused
+  **    meta[9]   unused
+  **
+  ** Note: The #defined SQLITE_UTF* symbols in sqliteInt.h correspond to
+  ** the possible values of meta[4].
+  */
+  for(i=0; i<ArraySize(meta); i++){
+    sqlite3BtreeGetMeta(pDb->pBt, i+1, (u32 *)&meta[i]);
+  }
+  pDb->pSchema->schema_cookie = meta[BTREE_SCHEMA_VERSION-1];
+
+  /* If opening a non-empty database, check the text encoding. For the
+  ** main database, set sqlite3.enc to the encoding of the main database.
+  ** For an attached db, it is an error if the encoding is not the same
+  ** as sqlite3.enc.
+  */
+  if( meta[BTREE_TEXT_ENCODING-1] ){  /* text encoding */
+    if( iDb==0 ){
+#ifndef SQLITE_OMIT_UTF16
+      u8 encoding;
+      /* If opening the main database, set ENC(db). */
+      encoding = (u8)meta[BTREE_TEXT_ENCODING-1] & 3;
+      if( encoding==0 ) encoding = SQLITE_UTF8;
+      ENC(db) = encoding;
+#else
+      ENC(db) = SQLITE_UTF8;
+#endif
+    }else{
+      /* If opening an attached database, the encoding much match ENC(db) */
+      if( meta[BTREE_TEXT_ENCODING-1]!=ENC(db) ){
+        sqlite3SetString(pzErrMsg, db, "attached databases must use the same"
+            " text encoding as main database");
+        rc = SQLITE_ERROR;
+        goto initone_error_out;
+      }
+    }
+  }else{
+    DbSetProperty(db, iDb, DB_Empty);
+  }
+  pDb->pSchema->enc = ENC(db);
+
+  if( pDb->pSchema->cache_size==0 ){
+#ifndef SQLITE_OMIT_DEPRECATED
+    size = sqlite3AbsInt32(meta[BTREE_DEFAULT_CACHE_SIZE-1]);
+    if( size==0 ){ size = SQLITE_DEFAULT_CACHE_SIZE; }
+    pDb->pSchema->cache_size = size;
+#else
+    pDb->pSchema->cache_size = SQLITE_DEFAULT_CACHE_SIZE;
+#endif
+    sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size);
+  }
+
+  /*
+  ** file_format==1    Version 3.0.0.
+  ** file_format==2    Version 3.1.3.  // ALTER TABLE ADD COLUMN
+  ** file_format==3    Version 3.1.4.  // ditto but with non-NULL defaults
+  ** file_format==4    Version 3.3.0.  // DESC indices.  Boolean constants
+  */
+  pDb->pSchema->file_format = (u8)meta[BTREE_FILE_FORMAT-1];
+  if( pDb->pSchema->file_format==0 ){
+    pDb->pSchema->file_format = 1;
+  }
+  if( pDb->pSchema->file_format>SQLITE_MAX_FILE_FORMAT ){
+    sqlite3SetString(pzErrMsg, db, "unsupported file format");
+    rc = SQLITE_ERROR;
+    goto initone_error_out;
+  }
+
+  /* Ticket #2804:  When we open a database in the newer file format,
+  ** clear the legacy_file_format pragma flag so that a VACUUM will
+  ** not downgrade the database and thus invalidate any descending
+  ** indices that the user might have created.
+  */
+  if( iDb==0 && meta[BTREE_FILE_FORMAT-1]>=4 ){
+    db->flags &= ~SQLITE_LegacyFileFmt;
+  }
+
+  /* Read the schema information out of the schema tables
+  */
+  assert( db->init.busy );
+  {
+    char *zSql;
+    zSql = sqlite3MPrintf(db, 
+        "SELECT name, rootpage, sql FROM \"%w\".%s ORDER BY rowid",
+        db->aDb[iDb].zDbSName, zMasterName);
+#ifndef SQLITE_OMIT_AUTHORIZATION
+    {
+      sqlite3_xauth xAuth;
+      xAuth = db->xAuth;
+      db->xAuth = 0;
+#endif
+      rc = sqlite3_exec(db, zSql, sqlite3InitCallback, &initData, 0);
+#ifndef SQLITE_OMIT_AUTHORIZATION
+      db->xAuth = xAuth;
+    }
+#endif
+    if( rc==SQLITE_OK ) rc = initData.rc;
+    sqlite3DbFree(db, zSql);
+#ifndef SQLITE_OMIT_ANALYZE
+    if( rc==SQLITE_OK ){
+      sqlite3AnalysisLoad(db, iDb);
+    }
+#endif
+  }
+  if( db->mallocFailed ){
+    rc = SQLITE_NOMEM_BKPT;
+    sqlite3ResetAllSchemasOfConnection(db);
+  }
+  if( rc==SQLITE_OK || (db->flags&SQLITE_RecoveryMode)){
+    /* Black magic: If the SQLITE_RecoveryMode flag is set, then consider
+    ** the schema loaded, even if errors occurred. In this situation the 
+    ** current sqlite3_prepare() operation will fail, but the following one
+    ** will attempt to compile the supplied statement against whatever subset
+    ** of the schema was loaded before the error occurred. The primary
+    ** purpose of this is to allow access to the sqlite_master table
+    ** even when its contents have been corrupted.
+    */
+    DbSetProperty(db, iDb, DB_SchemaLoaded);
+    rc = SQLITE_OK;
+  }
+
+  /* Jump here for an error that occurs after successfully allocating
+  ** curMain and calling sqlite3BtreeEnter(). For an error that occurs
+  ** before that point, jump to error_out.
+  */
+initone_error_out:
+  if( openedTransaction ){
+    sqlite3BtreeCommit(pDb->pBt);
+  }
+  sqlite3BtreeLeave(pDb->pBt);
+
+error_out:
+  if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
+    sqlite3OomFault(db);
+  }
+  return rc;
+}
+
+/*
+** Initialize all database files - the main database file, the file
+** used to store temporary tables, and any additional database files
+** created using ATTACH statements.  Return a success code.  If an
+** error occurs, write an error message into *pzErrMsg.
+**
+** After a database is initialized, the DB_SchemaLoaded bit is set
+** bit is set in the flags field of the Db structure. If the database
+** file was of zero-length, then the DB_Empty flag is also set.
+*/
+SQLITE_PRIVATE int sqlite3Init(sqlite3 *db, char **pzErrMsg){
+  int i, rc;
+  int commit_internal = !(db->flags&SQLITE_InternChanges);
+  
+  assert( sqlite3_mutex_held(db->mutex) );
+  assert( sqlite3BtreeHoldsMutex(db->aDb[0].pBt) );
+  assert( db->init.busy==0 );
+  rc = SQLITE_OK;
+  db->init.busy = 1;
+  ENC(db) = SCHEMA_ENC(db);
+  for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
+    if( DbHasProperty(db, i, DB_SchemaLoaded) || i==1 ) continue;
+    rc = sqlite3InitOne(db, i, pzErrMsg);
+    if( rc ){
+      sqlite3ResetOneSchema(db, i);
+    }
+  }
+
+  /* Once all the other databases have been initialized, load the schema
+  ** for the TEMP database. This is loaded last, as the TEMP database
+  ** schema may contain references to objects in other databases.
+  */
+#ifndef SQLITE_OMIT_TEMPDB
+  assert( db->nDb>1 );
+  if( rc==SQLITE_OK && !DbHasProperty(db, 1, DB_SchemaLoaded) ){
+    rc = sqlite3InitOne(db, 1, pzErrMsg);
+    if( rc ){
+      sqlite3ResetOneSchema(db, 1);
+    }
+  }
+#endif
+
+  db->init.busy = 0;
+  if( rc==SQLITE_OK && commit_internal ){
+    sqlite3CommitInternalChanges(db);
+  }
+
+  return rc; 
+}
+
+/*
+** This routine is a no-op if the database schema is already initialized.
+** Otherwise, the schema is loaded. An error code is returned.
+*/
+SQLITE_PRIVATE int sqlite3ReadSchema(Parse *pParse){
+  int rc = SQLITE_OK;
+  sqlite3 *db = pParse->db;
+  assert( sqlite3_mutex_held(db->mutex) );
+  if( !db->init.busy ){
+    rc = sqlite3Init(db, &pParse->zErrMsg);
+  }
+  if( rc!=SQLITE_OK ){
+    pParse->rc = rc;
+    pParse->nErr++;
+  }
+  return rc;
+}
+
+
+/*
+** Check schema cookies in all databases.  If any cookie is out
+** of date set pParse->rc to SQLITE_SCHEMA.  If all schema cookies
+** make no changes to pParse->rc.
+*/
+static void schemaIsValid(Parse *pParse){
+  sqlite3 *db = pParse->db;
+  int iDb;
+  int rc;
+  int cookie;
+
+  assert( pParse->checkSchema );
+  assert( sqlite3_mutex_held(db->mutex) );
+  for(iDb=0; iDb<db->nDb; iDb++){
+    int openedTransaction = 0;         /* True if a transaction is opened */
+    Btree *pBt = db->aDb[iDb].pBt;     /* Btree database to read cookie from */
+    if( pBt==0 ) continue;
+
+    /* If there is not already a read-only (or read-write) transaction opened
+    ** on the b-tree database, open one now. If a transaction is opened, it 
+    ** will be closed immediately after reading the meta-value. */
+    if( !sqlite3BtreeIsInReadTrans(pBt) ){
+      rc = sqlite3BtreeBeginTrans(pBt, 0);
+      if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
+        sqlite3OomFault(db);
+      }
+      if( rc!=SQLITE_OK ) return;
+      openedTransaction = 1;
+    }
+
+    /* Read the schema cookie from the database. If it does not match the 
+    ** value stored as part of the in-memory schema representation,
+    ** set Parse.rc to SQLITE_SCHEMA. */
+    sqlite3BtreeGetMeta(pBt, BTREE_SCHEMA_VERSION, (u32 *)&cookie);
+    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+    if( cookie!=db->aDb[iDb].pSchema->schema_cookie ){
+      sqlite3ResetOneSchema(db, iDb);
+      pParse->rc = SQLITE_SCHEMA;
+    }
+
+    /* Close the transaction, if one was opened. */
+    if( openedTransaction ){
+      sqlite3BtreeCommit(pBt);
+    }
+  }
+}
+
+/*
+** Convert a schema pointer into the iDb index that indicates
+** which database file in db->aDb[] the schema refers to.
+**
+** If the same database is attached more than once, the first
+** attached database is returned.
+*/
+SQLITE_PRIVATE int sqlite3SchemaToIndex(sqlite3 *db, Schema *pSchema){
+  int i = -1000000;
+
+  /* If pSchema is NULL, then return -1000000. This happens when code in 
+  ** expr.c is trying to resolve a reference to a transient table (i.e. one
+  ** created by a sub-select). In this case the return value of this 
+  ** function should never be used.
+  **
+  ** We return -1000000 instead of the more usual -1 simply because using
+  ** -1000000 as the incorrect index into db->aDb[] is much 
+  ** more likely to cause a segfault than -1 (of course there are assert()
+  ** statements too, but it never hurts to play the odds).
+  */
+  assert( sqlite3_mutex_held(db->mutex) );
+  if( pSchema ){
+    for(i=0; ALWAYS(i<db->nDb); i++){
+      if( db->aDb[i].pSchema==pSchema ){
+        break;
+      }
+    }
+    assert( i>=0 && i<db->nDb );
+  }
+  return i;
+}
+
+/*
+** Free all memory allocations in the pParse object
+*/
+SQLITE_PRIVATE void sqlite3ParserReset(Parse *pParse){
+  if( pParse ){
+    sqlite3 *db = pParse->db;
+    sqlite3DbFree(db, pParse->aLabel);
+    sqlite3ExprListDelete(db, pParse->pConstExpr);
+    if( db ){
+      assert( db->lookaside.bDisable >= pParse->disableLookaside );
+      db->lookaside.bDisable -= pParse->disableLookaside;
+    }
+    pParse->disableLookaside = 0;
+  }
+}
+
+/*
+** Compile the UTF-8 encoded SQL statement zSql into a statement handle.
+*/
+static int sqlite3Prepare(
+  sqlite3 *db,              /* Database handle. */
+  const char *zSql,         /* UTF-8 encoded SQL statement. */
+  int nBytes,               /* Length of zSql in bytes. */
+  int saveSqlFlag,          /* True to copy SQL text into the sqlite3_stmt */
+  Vdbe *pReprepare,         /* VM being reprepared */
+  sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
+  const char **pzTail       /* OUT: End of parsed string */
+){
+  char *zErrMsg = 0;        /* Error message */
+  int rc = SQLITE_OK;       /* Result code */
+  int i;                    /* Loop counter */
+  Parse sParse;             /* Parsing context */
+
+  memset(&sParse, 0, PARSE_HDR_SZ);
+  memset(PARSE_TAIL(&sParse), 0, PARSE_TAIL_SZ);
+  sParse.pReprepare = pReprepare;
+  assert( ppStmt && *ppStmt==0 );
+  /* assert( !db->mallocFailed ); // not true with SQLITE_USE_ALLOCA */
+  assert( sqlite3_mutex_held(db->mutex) );
+
+  /* Check to verify that it is possible to get a read lock on all
+  ** database schemas.  The inability to get a read lock indicates that
+  ** some other database connection is holding a write-lock, which in
+  ** turn means that the other connection has made uncommitted changes
+  ** to the schema.
+  **
+  ** Were we to proceed and prepare the statement against the uncommitted
+  ** schema changes and if those schema changes are subsequently rolled
+  ** back and different changes are made in their place, then when this
+  ** prepared statement goes to run the schema cookie would fail to detect
+  ** the schema change.  Disaster would follow.
+  **
+  ** This thread is currently holding mutexes on all Btrees (because
+  ** of the sqlite3BtreeEnterAll() in sqlite3LockAndPrepare()) so it
+  ** is not possible for another thread to start a new schema change
+  ** while this routine is running.  Hence, we do not need to hold 
+  ** locks on the schema, we just need to make sure nobody else is 
+  ** holding them.
+  **
+  ** Note that setting READ_UNCOMMITTED overrides most lock detection,
+  ** but it does *not* override schema lock detection, so this all still
+  ** works even if READ_UNCOMMITTED is set.
+  */
+  for(i=0; i<db->nDb; i++) {
+    Btree *pBt = db->aDb[i].pBt;
+    if( pBt ){
+      assert( sqlite3BtreeHoldsMutex(pBt) );
+      rc = sqlite3BtreeSchemaLocked(pBt);
+      if( rc ){
+        const char *zDb = db->aDb[i].zDbSName;
+        sqlite3ErrorWithMsg(db, rc, "database schema is locked: %s", zDb);
+        testcase( db->flags & SQLITE_ReadUncommitted );
+        goto end_prepare;
+      }
+    }
+  }
+
+  sqlite3VtabUnlockList(db);
+
+  sParse.db = db;
+  if( nBytes>=0 && (nBytes==0 || zSql[nBytes-1]!=0) ){
+    char *zSqlCopy;
+    int mxLen = db->aLimit[SQLITE_LIMIT_SQL_LENGTH];
+    testcase( nBytes==mxLen );
+    testcase( nBytes==mxLen+1 );
+    if( nBytes>mxLen ){
+      sqlite3ErrorWithMsg(db, SQLITE_TOOBIG, "statement too long");
+      rc = sqlite3ApiExit(db, SQLITE_TOOBIG);
+      goto end_prepare;
+    }
+    zSqlCopy = sqlite3DbStrNDup(db, zSql, nBytes);
+    if( zSqlCopy ){
+      sqlite3RunParser(&sParse, zSqlCopy, &zErrMsg);
+      sParse.zTail = &zSql[sParse.zTail-zSqlCopy];
+      sqlite3DbFree(db, zSqlCopy);
+    }else{
+      sParse.zTail = &zSql[nBytes];
+    }
+  }else{
+    sqlite3RunParser(&sParse, zSql, &zErrMsg);
+  }
+  assert( 0==sParse.nQueryLoop );
+
+  if( sParse.rc==SQLITE_DONE ) sParse.rc = SQLITE_OK;
+  if( sParse.checkSchema ){
+    schemaIsValid(&sParse);
+  }
+  if( db->mallocFailed ){
+    sParse.rc = SQLITE_NOMEM_BKPT;
+  }
+  if( pzTail ){
+    *pzTail = sParse.zTail;
+  }
+  rc = sParse.rc;
+
+#ifndef SQLITE_OMIT_EXPLAIN
+  if( rc==SQLITE_OK && sParse.pVdbe && sParse.explain ){
+    static const char * const azColName[] = {
+       "addr", "opcode", "p1", "p2", "p3", "p4", "p5", "comment",
+       "selectid", "order", "from", "detail"
+    };
+    int iFirst, mx;
+    if( sParse.explain==2 ){
+      sqlite3VdbeSetNumCols(sParse.pVdbe, 4);
+      iFirst = 8;
+      mx = 12;
+    }else{
+      sqlite3VdbeSetNumCols(sParse.pVdbe, 8);
+      iFirst = 0;
+      mx = 8;
+    }
+    for(i=iFirst; i<mx; i++){
+      sqlite3VdbeSetColName(sParse.pVdbe, i-iFirst, COLNAME_NAME,
+                            azColName[i], SQLITE_STATIC);
+    }
+  }
+#endif
+
+  if( db->init.busy==0 ){
+    Vdbe *pVdbe = sParse.pVdbe;
+    sqlite3VdbeSetSql(pVdbe, zSql, (int)(sParse.zTail-zSql), saveSqlFlag);
+  }
+  if( sParse.pVdbe && (rc!=SQLITE_OK || db->mallocFailed) ){
+    sqlite3VdbeFinalize(sParse.pVdbe);
+    assert(!(*ppStmt));
+  }else{
+    *ppStmt = (sqlite3_stmt*)sParse.pVdbe;
+  }
+
+  if( zErrMsg ){
+    sqlite3ErrorWithMsg(db, rc, "%s", zErrMsg);
+    sqlite3DbFree(db, zErrMsg);
+  }else{
+    sqlite3Error(db, rc);
+  }
+
+  /* Delete any TriggerPrg structures allocated while parsing this statement. */
+  while( sParse.pTriggerPrg ){
+    TriggerPrg *pT = sParse.pTriggerPrg;
+    sParse.pTriggerPrg = pT->pNext;
+    sqlite3DbFree(db, pT);
+  }
+
+end_prepare:
+
+  sqlite3ParserReset(&sParse);
+  rc = sqlite3ApiExit(db, rc);
+  assert( (rc&db->errMask)==rc );
+  return rc;
+}
+static int sqlite3LockAndPrepare(
+  sqlite3 *db,              /* Database handle. */
+  const char *zSql,         /* UTF-8 encoded SQL statement. */
+  int nBytes,               /* Length of zSql in bytes. */
+  int saveSqlFlag,          /* True to copy SQL text into the sqlite3_stmt */
+  Vdbe *pOld,               /* VM being reprepared */
+  sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
+  const char **pzTail       /* OUT: End of parsed string */
+){
+  int rc;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( ppStmt==0 ) return SQLITE_MISUSE_BKPT;
+#endif
+  *ppStmt = 0;
+  if( !sqlite3SafetyCheckOk(db)||zSql==0 ){
+    return SQLITE_MISUSE_BKPT;
+  }
+  sqlite3_mutex_enter(db->mutex);
+  sqlite3BtreeEnterAll(db);
+  rc = sqlite3Prepare(db, zSql, nBytes, saveSqlFlag, pOld, ppStmt, pzTail);
+  if( rc==SQLITE_SCHEMA ){
+    sqlite3_finalize(*ppStmt);
+    rc = sqlite3Prepare(db, zSql, nBytes, saveSqlFlag, pOld, ppStmt, pzTail);
+  }
+  sqlite3BtreeLeaveAll(db);
+  sqlite3_mutex_leave(db->mutex);
+  assert( rc==SQLITE_OK || *ppStmt==0 );
+  return rc;
+}
+
+/*
+** Rerun the compilation of a statement after a schema change.
+**
+** If the statement is successfully recompiled, return SQLITE_OK. Otherwise,
+** if the statement cannot be recompiled because another connection has
+** locked the sqlite3_master table, return SQLITE_LOCKED. If any other error
+** occurs, return SQLITE_SCHEMA.
+*/
+SQLITE_PRIVATE int sqlite3Reprepare(Vdbe *p){
+  int rc;
+  sqlite3_stmt *pNew;
+  const char *zSql;
+  sqlite3 *db;
+
+  assert( sqlite3_mutex_held(sqlite3VdbeDb(p)->mutex) );
+  zSql = sqlite3_sql((sqlite3_stmt *)p);
+  assert( zSql!=0 );  /* Reprepare only called for prepare_v2() statements */
+  db = sqlite3VdbeDb(p);
+  assert( sqlite3_mutex_held(db->mutex) );
+  rc = sqlite3LockAndPrepare(db, zSql, -1, 0, p, &pNew, 0);
+  if( rc ){
+    if( rc==SQLITE_NOMEM ){
+      sqlite3OomFault(db);
+    }
+    assert( pNew==0 );
+    return rc;
+  }else{
+    assert( pNew!=0 );
+  }
+  sqlite3VdbeSwap((Vdbe*)pNew, p);
+  sqlite3TransferBindings(pNew, (sqlite3_stmt*)p);
+  sqlite3VdbeResetStepResult((Vdbe*)pNew);
+  sqlite3VdbeFinalize((Vdbe*)pNew);
+  return SQLITE_OK;
+}
+
+
+/*
+** Two versions of the official API.  Legacy and new use.  In the legacy
+** version, the original SQL text is not saved in the prepared statement
+** and so if a schema change occurs, SQLITE_SCHEMA is returned by
+** sqlite3_step().  In the new version, the original SQL text is retained
+** and the statement is automatically recompiled if an schema change
+** occurs.
+*/
+SQLITE_API int sqlite3_prepare(
+  sqlite3 *db,              /* Database handle. */
+  const char *zSql,         /* UTF-8 encoded SQL statement. */
+  int nBytes,               /* Length of zSql in bytes. */
+  sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
+  const char **pzTail       /* OUT: End of parsed string */
+){
+  int rc;
+  rc = sqlite3LockAndPrepare(db,zSql,nBytes,0,0,ppStmt,pzTail);
+  assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 );  /* VERIFY: F13021 */
+  return rc;
+}
+SQLITE_API int sqlite3_prepare_v2(
+  sqlite3 *db,              /* Database handle. */
+  const char *zSql,         /* UTF-8 encoded SQL statement. */
+  int nBytes,               /* Length of zSql in bytes. */
+  sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
+  const char **pzTail       /* OUT: End of parsed string */
+){
+  int rc;
+  rc = sqlite3LockAndPrepare(db,zSql,nBytes,1,0,ppStmt,pzTail);
+  assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 );  /* VERIFY: F13021 */
+  return rc;
+}
+
+
+#ifndef SQLITE_OMIT_UTF16
+/*
+** Compile the UTF-16 encoded SQL statement zSql into a statement handle.
+*/
+static int sqlite3Prepare16(
+  sqlite3 *db,              /* Database handle. */ 
+  const void *zSql,         /* UTF-16 encoded SQL statement. */
+  int nBytes,               /* Length of zSql in bytes. */
+  int saveSqlFlag,          /* True to save SQL text into the sqlite3_stmt */
+  sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
+  const void **pzTail       /* OUT: End of parsed string */
+){
+  /* This function currently works by first transforming the UTF-16
+  ** encoded string to UTF-8, then invoking sqlite3_prepare(). The
+  ** tricky bit is figuring out the pointer to return in *pzTail.
+  */
+  char *zSql8;
+  const char *zTail8 = 0;
+  int rc = SQLITE_OK;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( ppStmt==0 ) return SQLITE_MISUSE_BKPT;
+#endif
+  *ppStmt = 0;
+  if( !sqlite3SafetyCheckOk(db)||zSql==0 ){
+    return SQLITE_MISUSE_BKPT;
+  }
+  if( nBytes>=0 ){
+    int sz;
+    const char *z = (const char*)zSql;
+    for(sz=0; sz<nBytes && (z[sz]!=0 || z[sz+1]!=0); sz += 2){}
+    nBytes = sz;
+  }
+  sqlite3_mutex_enter(db->mutex);
+  zSql8 = sqlite3Utf16to8(db, zSql, nBytes, SQLITE_UTF16NATIVE);
+  if( zSql8 ){
+    rc = sqlite3LockAndPrepare(db, zSql8, -1, saveSqlFlag, 0, ppStmt, &zTail8);
+  }
+
+  if( zTail8 && pzTail ){
+    /* If sqlite3_prepare returns a tail pointer, we calculate the
+    ** equivalent pointer into the UTF-16 string by counting the unicode
+    ** characters between zSql8 and zTail8, and then returning a pointer
+    ** the same number of characters into the UTF-16 string.
+    */
+    int chars_parsed = sqlite3Utf8CharLen(zSql8, (int)(zTail8-zSql8));
+    *pzTail = (u8 *)zSql + sqlite3Utf16ByteLen(zSql, chars_parsed);
+  }
+  sqlite3DbFree(db, zSql8); 
+  rc = sqlite3ApiExit(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+/*
+** Two versions of the official API.  Legacy and new use.  In the legacy
+** version, the original SQL text is not saved in the prepared statement
+** and so if a schema change occurs, SQLITE_SCHEMA is returned by
+** sqlite3_step().  In the new version, the original SQL text is retained
+** and the statement is automatically recompiled if an schema change
+** occurs.
+*/
+SQLITE_API int sqlite3_prepare16(
+  sqlite3 *db,              /* Database handle. */ 
+  const void *zSql,         /* UTF-16 encoded SQL statement. */
+  int nBytes,               /* Length of zSql in bytes. */
+  sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
+  const void **pzTail       /* OUT: End of parsed string */
+){
+  int rc;
+  rc = sqlite3Prepare16(db,zSql,nBytes,0,ppStmt,pzTail);
+  assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 );  /* VERIFY: F13021 */
+  return rc;
+}
+SQLITE_API int sqlite3_prepare16_v2(
+  sqlite3 *db,              /* Database handle. */ 
+  const void *zSql,         /* UTF-16 encoded SQL statement. */
+  int nBytes,               /* Length of zSql in bytes. */
+  sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
+  const void **pzTail       /* OUT: End of parsed string */
+){
+  int rc;
+  rc = sqlite3Prepare16(db,zSql,nBytes,1,ppStmt,pzTail);
+  assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 );  /* VERIFY: F13021 */
+  return rc;
+}
+
+#endif /* SQLITE_OMIT_UTF16 */
+
+/************** End of prepare.c *********************************************/
+/************** Begin file select.c ******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains C code routines that are called by the parser
+** to handle SELECT statements in SQLite.
+*/
+/* #include "sqliteInt.h" */
+
+/*
+** Trace output macros
+*/
+#if SELECTTRACE_ENABLED
+/***/ int sqlite3SelectTrace = 0;
+# define SELECTTRACE(K,P,S,X)  \
+  if(sqlite3SelectTrace&(K))   \
+    sqlite3DebugPrintf("%*s%s.%p: ",(P)->nSelectIndent*2-2,"",\
+        (S)->zSelName,(S)),\
+    sqlite3DebugPrintf X
+#else
+# define SELECTTRACE(K,P,S,X)
+#endif
+
+
+/*
+** An instance of the following object is used to record information about
+** how to process the DISTINCT keyword, to simplify passing that information
+** into the selectInnerLoop() routine.
+*/
+typedef struct DistinctCtx DistinctCtx;
+struct DistinctCtx {
+  u8 isTnct;      /* True if the DISTINCT keyword is present */
+  u8 eTnctType;   /* One of the WHERE_DISTINCT_* operators */
+  int tabTnct;    /* Ephemeral table used for DISTINCT processing */
+  int addrTnct;   /* Address of OP_OpenEphemeral opcode for tabTnct */
+};
+
+/*
+** An instance of the following object is used to record information about
+** the ORDER BY (or GROUP BY) clause of query is being coded.
+*/
+typedef struct SortCtx SortCtx;
+struct SortCtx {
+  ExprList *pOrderBy;   /* The ORDER BY (or GROUP BY clause) */
+  int nOBSat;           /* Number of ORDER BY terms satisfied by indices */
+  int iECursor;         /* Cursor number for the sorter */
+  int regReturn;        /* Register holding block-output return address */
+  int labelBkOut;       /* Start label for the block-output subroutine */
+  int addrSortIndex;    /* Address of the OP_SorterOpen or OP_OpenEphemeral */
+  int labelDone;        /* Jump here when done, ex: LIMIT reached */
+  u8 sortFlags;         /* Zero or more SORTFLAG_* bits */
+  u8 bOrderedInnerLoop; /* ORDER BY correctly sorts the inner loop */
+};
+#define SORTFLAG_UseSorter  0x01   /* Use SorterOpen instead of OpenEphemeral */
+
+/*
+** Delete all the content of a Select structure.  Deallocate the structure
+** itself only if bFree is true.
+*/
+static void clearSelect(sqlite3 *db, Select *p, int bFree){
+  while( p ){
+    Select *pPrior = p->pPrior;
+    sqlite3ExprListDelete(db, p->pEList);
+    sqlite3SrcListDelete(db, p->pSrc);
+    sqlite3ExprDelete(db, p->pWhere);
+    sqlite3ExprListDelete(db, p->pGroupBy);
+    sqlite3ExprDelete(db, p->pHaving);
+    sqlite3ExprListDelete(db, p->pOrderBy);
+    sqlite3ExprDelete(db, p->pLimit);
+    sqlite3ExprDelete(db, p->pOffset);
+    if( p->pWith ) sqlite3WithDelete(db, p->pWith);
+    if( bFree ) sqlite3DbFree(db, p);
+    p = pPrior;
+    bFree = 1;
+  }
+}
+
+/*
+** Initialize a SelectDest structure.
+*/
+SQLITE_PRIVATE void sqlite3SelectDestInit(SelectDest *pDest, int eDest, int iParm){
+  pDest->eDest = (u8)eDest;
+  pDest->iSDParm = iParm;
+  pDest->zAffSdst = 0;
+  pDest->iSdst = 0;
+  pDest->nSdst = 0;
+}
+
+
+/*
+** Allocate a new Select structure and return a pointer to that
+** structure.
+*/
+SQLITE_PRIVATE Select *sqlite3SelectNew(
+  Parse *pParse,        /* Parsing context */
+  ExprList *pEList,     /* which columns to include in the result */
+  SrcList *pSrc,        /* the FROM clause -- which tables to scan */
+  Expr *pWhere,         /* the WHERE clause */
+  ExprList *pGroupBy,   /* the GROUP BY clause */
+  Expr *pHaving,        /* the HAVING clause */
+  ExprList *pOrderBy,   /* the ORDER BY clause */
+  u32 selFlags,         /* Flag parameters, such as SF_Distinct */
+  Expr *pLimit,         /* LIMIT value.  NULL means not used */
+  Expr *pOffset         /* OFFSET value.  NULL means no offset */
+){
+  Select *pNew;
+  Select standin;
+  sqlite3 *db = pParse->db;
+  pNew = sqlite3DbMallocRawNN(db, sizeof(*pNew) );
+  if( pNew==0 ){
+    assert( db->mallocFailed );
+    pNew = &standin;
+  }
+  if( pEList==0 ){
+    pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db,TK_ASTERISK,0));
+  }
+  pNew->pEList = pEList;
+  pNew->op = TK_SELECT;
+  pNew->selFlags = selFlags;
+  pNew->iLimit = 0;
+  pNew->iOffset = 0;
+#if SELECTTRACE_ENABLED
+  pNew->zSelName[0] = 0;
+#endif
+  pNew->addrOpenEphm[0] = -1;
+  pNew->addrOpenEphm[1] = -1;
+  pNew->nSelectRow = 0;
+  if( pSrc==0 ) pSrc = sqlite3DbMallocZero(db, sizeof(*pSrc));
+  pNew->pSrc = pSrc;
+  pNew->pWhere = pWhere;
+  pNew->pGroupBy = pGroupBy;
+  pNew->pHaving = pHaving;
+  pNew->pOrderBy = pOrderBy;
+  pNew->pPrior = 0;
+  pNew->pNext = 0;
+  pNew->pLimit = pLimit;
+  pNew->pOffset = pOffset;
+  pNew->pWith = 0;
+  assert( pOffset==0 || pLimit!=0 || pParse->nErr>0 || db->mallocFailed!=0 );
+  if( db->mallocFailed ) {
+    clearSelect(db, pNew, pNew!=&standin);
+    pNew = 0;
+  }else{
+    assert( pNew->pSrc!=0 || pParse->nErr>0 );
+  }
+  assert( pNew!=&standin );
+  return pNew;
+}
+
+#if SELECTTRACE_ENABLED
+/*
+** Set the name of a Select object
+*/
+SQLITE_PRIVATE void sqlite3SelectSetName(Select *p, const char *zName){
+  if( p && zName ){
+    sqlite3_snprintf(sizeof(p->zSelName), p->zSelName, "%s", zName);
+  }
+}
+#endif
+
+
+/*
+** Delete the given Select structure and all of its substructures.
+*/
+SQLITE_PRIVATE void sqlite3SelectDelete(sqlite3 *db, Select *p){
+  if( p ) clearSelect(db, p, 1);
+}
+
+/*
+** Return a pointer to the right-most SELECT statement in a compound.
+*/
+static Select *findRightmost(Select *p){
+  while( p->pNext ) p = p->pNext;
+  return p;
+}
+
+/*
+** Given 1 to 3 identifiers preceding the JOIN keyword, determine the
+** type of join.  Return an integer constant that expresses that type
+** in terms of the following bit values:
+**
+**     JT_INNER
+**     JT_CROSS
+**     JT_OUTER
+**     JT_NATURAL
+**     JT_LEFT
+**     JT_RIGHT
+**
+** A full outer join is the combination of JT_LEFT and JT_RIGHT.
+**
+** If an illegal or unsupported join type is seen, then still return
+** a join type, but put an error in the pParse structure.
+*/
+SQLITE_PRIVATE int sqlite3JoinType(Parse *pParse, Token *pA, Token *pB, Token *pC){
+  int jointype = 0;
+  Token *apAll[3];
+  Token *p;
+                             /*   0123456789 123456789 123456789 123 */
+  static const char zKeyText[] = "naturaleftouterightfullinnercross";
+  static const struct {
+    u8 i;        /* Beginning of keyword text in zKeyText[] */
+    u8 nChar;    /* Length of the keyword in characters */
+    u8 code;     /* Join type mask */
+  } aKeyword[] = {
+    /* natural */ { 0,  7, JT_NATURAL                },
+    /* left    */ { 6,  4, JT_LEFT|JT_OUTER          },
+    /* outer   */ { 10, 5, JT_OUTER                  },
+    /* right   */ { 14, 5, JT_RIGHT|JT_OUTER         },
+    /* full    */ { 19, 4, JT_LEFT|JT_RIGHT|JT_OUTER },
+    /* inner   */ { 23, 5, JT_INNER                  },
+    /* cross   */ { 28, 5, JT_INNER|JT_CROSS         },
+  };
+  int i, j;
+  apAll[0] = pA;
+  apAll[1] = pB;
+  apAll[2] = pC;
+  for(i=0; i<3 && apAll[i]; i++){
+    p = apAll[i];
+    for(j=0; j<ArraySize(aKeyword); j++){
+      if( p->n==aKeyword[j].nChar 
+          && sqlite3StrNICmp((char*)p->z, &zKeyText[aKeyword[j].i], p->n)==0 ){
+        jointype |= aKeyword[j].code;
+        break;
+      }
+    }
+    testcase( j==0 || j==1 || j==2 || j==3 || j==4 || j==5 || j==6 );
+    if( j>=ArraySize(aKeyword) ){
+      jointype |= JT_ERROR;
+      break;
+    }
+  }
+  if(
+     (jointype & (JT_INNER|JT_OUTER))==(JT_INNER|JT_OUTER) ||
+     (jointype & JT_ERROR)!=0
+  ){
+    const char *zSp = " ";
+    assert( pB!=0 );
+    if( pC==0 ){ zSp++; }
+    sqlite3ErrorMsg(pParse, "unknown or unsupported join type: "
+       "%T %T%s%T", pA, pB, zSp, pC);
+    jointype = JT_INNER;
+  }else if( (jointype & JT_OUTER)!=0 
+         && (jointype & (JT_LEFT|JT_RIGHT))!=JT_LEFT ){
+    sqlite3ErrorMsg(pParse, 
+      "RIGHT and FULL OUTER JOINs are not currently supported");
+    jointype = JT_INNER;
+  }
+  return jointype;
+}
+
+/*
+** Return the index of a column in a table.  Return -1 if the column
+** is not contained in the table.
+*/
+static int columnIndex(Table *pTab, const char *zCol){
+  int i;
+  for(i=0; i<pTab->nCol; i++){
+    if( sqlite3StrICmp(pTab->aCol[i].zName, zCol)==0 ) return i;
+  }
+  return -1;
+}
+
+/*
+** Search the first N tables in pSrc, from left to right, looking for a
+** table that has a column named zCol.  
+**
+** When found, set *piTab and *piCol to the table index and column index
+** of the matching column and return TRUE.
+**
+** If not found, return FALSE.
+*/
+static int tableAndColumnIndex(
+  SrcList *pSrc,       /* Array of tables to search */
+  int N,               /* Number of tables in pSrc->a[] to search */
+  const char *zCol,    /* Name of the column we are looking for */
+  int *piTab,          /* Write index of pSrc->a[] here */
+  int *piCol           /* Write index of pSrc->a[*piTab].pTab->aCol[] here */
+){
+  int i;               /* For looping over tables in pSrc */
+  int iCol;            /* Index of column matching zCol */
+
+  assert( (piTab==0)==(piCol==0) );  /* Both or neither are NULL */
+  for(i=0; i<N; i++){
+    iCol = columnIndex(pSrc->a[i].pTab, zCol);
+    if( iCol>=0 ){
+      if( piTab ){
+        *piTab = i;
+        *piCol = iCol;
+      }
+      return 1;
+    }
+  }
+  return 0;
+}
+
+/*
+** This function is used to add terms implied by JOIN syntax to the
+** WHERE clause expression of a SELECT statement. The new term, which
+** is ANDed with the existing WHERE clause, is of the form:
+**
+**    (tab1.col1 = tab2.col2)
+**
+** where tab1 is the iSrc'th table in SrcList pSrc and tab2 is the 
+** (iSrc+1)'th. Column col1 is column iColLeft of tab1, and col2 is
+** column iColRight of tab2.
+*/
+static void addWhereTerm(
+  Parse *pParse,                  /* Parsing context */
+  SrcList *pSrc,                  /* List of tables in FROM clause */
+  int iLeft,                      /* Index of first table to join in pSrc */
+  int iColLeft,                   /* Index of column in first table */
+  int iRight,                     /* Index of second table in pSrc */
+  int iColRight,                  /* Index of column in second table */
+  int isOuterJoin,                /* True if this is an OUTER join */
+  Expr **ppWhere                  /* IN/OUT: The WHERE clause to add to */
+){
+  sqlite3 *db = pParse->db;
+  Expr *pE1;
+  Expr *pE2;
+  Expr *pEq;
+
+  assert( iLeft<iRight );
+  assert( pSrc->nSrc>iRight );
+  assert( pSrc->a[iLeft].pTab );
+  assert( pSrc->a[iRight].pTab );
+
+  pE1 = sqlite3CreateColumnExpr(db, pSrc, iLeft, iColLeft);
+  pE2 = sqlite3CreateColumnExpr(db, pSrc, iRight, iColRight);
+
+  pEq = sqlite3PExpr(pParse, TK_EQ, pE1, pE2, 0);
+  if( pEq && isOuterJoin ){
+    ExprSetProperty(pEq, EP_FromJoin);
+    assert( !ExprHasProperty(pEq, EP_TokenOnly|EP_Reduced) );
+    ExprSetVVAProperty(pEq, EP_NoReduce);
+    pEq->iRightJoinTable = (i16)pE2->iTable;
+  }
+  *ppWhere = sqlite3ExprAnd(db, *ppWhere, pEq);
+}
+
+/*
+** Set the EP_FromJoin property on all terms of the given expression.
+** And set the Expr.iRightJoinTable to iTable for every term in the
+** expression.
+**
+** The EP_FromJoin property is used on terms of an expression to tell
+** the LEFT OUTER JOIN processing logic that this term is part of the
+** join restriction specified in the ON or USING clause and not a part
+** of the more general WHERE clause.  These terms are moved over to the
+** WHERE clause during join processing but we need to remember that they
+** originated in the ON or USING clause.
+**
+** The Expr.iRightJoinTable tells the WHERE clause processing that the
+** expression depends on table iRightJoinTable even if that table is not
+** explicitly mentioned in the expression.  That information is needed
+** for cases like this:
+**
+**    SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.b AND t1.x=5
+**
+** The where clause needs to defer the handling of the t1.x=5
+** term until after the t2 loop of the join.  In that way, a
+** NULL t2 row will be inserted whenever t1.x!=5.  If we do not
+** defer the handling of t1.x=5, it will be processed immediately
+** after the t1 loop and rows with t1.x!=5 will never appear in
+** the output, which is incorrect.
+*/
+static void setJoinExpr(Expr *p, int iTable){
+  while( p ){
+    ExprSetProperty(p, EP_FromJoin);
+    assert( !ExprHasProperty(p, EP_TokenOnly|EP_Reduced) );
+    ExprSetVVAProperty(p, EP_NoReduce);
+    p->iRightJoinTable = (i16)iTable;
+    if( p->op==TK_FUNCTION && p->x.pList ){
+      int i;
+      for(i=0; i<p->x.pList->nExpr; i++){
+        setJoinExpr(p->x.pList->a[i].pExpr, iTable);
+      }
+    }
+    setJoinExpr(p->pLeft, iTable);
+    p = p->pRight;
+  } 
+}
+
+/*
+** This routine processes the join information for a SELECT statement.
+** ON and USING clauses are converted into extra terms of the WHERE clause.
+** NATURAL joins also create extra WHERE clause terms.
+**
+** The terms of a FROM clause are contained in the Select.pSrc structure.
+** The left most table is the first entry in Select.pSrc.  The right-most
+** table is the last entry.  The join operator is held in the entry to
+** the left.  Thus entry 0 contains the join operator for the join between
+** entries 0 and 1.  Any ON or USING clauses associated with the join are
+** also attached to the left entry.
+**
+** This routine returns the number of errors encountered.
+*/
+static int sqliteProcessJoin(Parse *pParse, Select *p){
+  SrcList *pSrc;                  /* All tables in the FROM clause */
+  int i, j;                       /* Loop counters */
+  struct SrcList_item *pLeft;     /* Left table being joined */
+  struct SrcList_item *pRight;    /* Right table being joined */
+
+  pSrc = p->pSrc;
+  pLeft = &pSrc->a[0];
+  pRight = &pLeft[1];
+  for(i=0; i<pSrc->nSrc-1; i++, pRight++, pLeft++){
+    Table *pLeftTab = pLeft->pTab;
+    Table *pRightTab = pRight->pTab;
+    int isOuter;
+
+    if( NEVER(pLeftTab==0 || pRightTab==0) ) continue;
+    isOuter = (pRight->fg.jointype & JT_OUTER)!=0;
+
+    /* When the NATURAL keyword is present, add WHERE clause terms for
+    ** every column that the two tables have in common.
+    */
+    if( pRight->fg.jointype & JT_NATURAL ){
+      if( pRight->pOn || pRight->pUsing ){
+        sqlite3ErrorMsg(pParse, "a NATURAL join may not have "
+           "an ON or USING clause", 0);
+        return 1;
+      }
+      for(j=0; j<pRightTab->nCol; j++){
+        char *zName;   /* Name of column in the right table */
+        int iLeft;     /* Matching left table */
+        int iLeftCol;  /* Matching column in the left table */
+
+        zName = pRightTab->aCol[j].zName;
+        if( tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol) ){
+          addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, j,
+                       isOuter, &p->pWhere);
+        }
+      }
+    }
+
+    /* Disallow both ON and USING clauses in the same join
+    */
+    if( pRight->pOn && pRight->pUsing ){
+      sqlite3ErrorMsg(pParse, "cannot have both ON and USING "
+        "clauses in the same join");
+      return 1;
+    }
+
+    /* Add the ON clause to the end of the WHERE clause, connected by
+    ** an AND operator.
+    */
+    if( pRight->pOn ){
+      if( isOuter ) setJoinExpr(pRight->pOn, pRight->iCursor);
+      p->pWhere = sqlite3ExprAnd(pParse->db, p->pWhere, pRight->pOn);
+      pRight->pOn = 0;
+    }
+
+    /* Create extra terms on the WHERE clause for each column named
+    ** in the USING clause.  Example: If the two tables to be joined are 
+    ** A and B and the USING clause names X, Y, and Z, then add this
+    ** to the WHERE clause:    A.X=B.X AND A.Y=B.Y AND A.Z=B.Z
+    ** Report an error if any column mentioned in the USING clause is
+    ** not contained in both tables to be joined.
+    */
+    if( pRight->pUsing ){
+      IdList *pList = pRight->pUsing;
+      for(j=0; j<pList->nId; j++){
+        char *zName;     /* Name of the term in the USING clause */
+        int iLeft;       /* Table on the left with matching column name */
+        int iLeftCol;    /* Column number of matching column on the left */
+        int iRightCol;   /* Column number of matching column on the right */
+
+        zName = pList->a[j].zName;
+        iRightCol = columnIndex(pRightTab, zName);
+        if( iRightCol<0
+         || !tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol)
+        ){
+          sqlite3ErrorMsg(pParse, "cannot join using column %s - column "
+            "not present in both tables", zName);
+          return 1;
+        }
+        addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, iRightCol,
+                     isOuter, &p->pWhere);
+      }
+    }
+  }
+  return 0;
+}
+
+/* Forward reference */
+static KeyInfo *keyInfoFromExprList(
+  Parse *pParse,       /* Parsing context */
+  ExprList *pList,     /* Form the KeyInfo object from this ExprList */
+  int iStart,          /* Begin with this column of pList */
+  int nExtra           /* Add this many extra columns to the end */
+);
+
+/*
+** Generate code that will push the record in registers regData
+** through regData+nData-1 onto the sorter.
+*/
+static void pushOntoSorter(
+  Parse *pParse,         /* Parser context */
+  SortCtx *pSort,        /* Information about the ORDER BY clause */
+  Select *pSelect,       /* The whole SELECT statement */
+  int regData,           /* First register holding data to be sorted */
+  int regOrigData,       /* First register holding data before packing */
+  int nData,             /* Number of elements in the data array */
+  int nPrefixReg         /* No. of reg prior to regData available for use */
+){
+  Vdbe *v = pParse->pVdbe;                         /* Stmt under construction */
+  int bSeq = ((pSort->sortFlags & SORTFLAG_UseSorter)==0);
+  int nExpr = pSort->pOrderBy->nExpr;              /* No. of ORDER BY terms */
+  int nBase = nExpr + bSeq + nData;                /* Fields in sorter record */
+  int regBase;                                     /* Regs for sorter record */
+  int regRecord = ++pParse->nMem;                  /* Assembled sorter record */
+  int nOBSat = pSort->nOBSat;                      /* ORDER BY terms to skip */
+  int op;                            /* Opcode to add sorter record to sorter */
+  int iLimit;                        /* LIMIT counter */
+
+  assert( bSeq==0 || bSeq==1 );
+  assert( nData==1 || regData==regOrigData );
+  if( nPrefixReg ){
+    assert( nPrefixReg==nExpr+bSeq );
+    regBase = regData - nExpr - bSeq;
+  }else{
+    regBase = pParse->nMem + 1;
+    pParse->nMem += nBase;
+  }
+  assert( pSelect->iOffset==0 || pSelect->iLimit!=0 );
+  iLimit = pSelect->iOffset ? pSelect->iOffset+1 : pSelect->iLimit;
+  pSort->labelDone = sqlite3VdbeMakeLabel(v);
+  sqlite3ExprCodeExprList(pParse, pSort->pOrderBy, regBase, regOrigData,
+                          SQLITE_ECEL_DUP|SQLITE_ECEL_REF);
+  if( bSeq ){
+    sqlite3VdbeAddOp2(v, OP_Sequence, pSort->iECursor, regBase+nExpr);
+  }
+  if( nPrefixReg==0 ){
+    sqlite3ExprCodeMove(pParse, regData, regBase+nExpr+bSeq, nData);
+  }
+  sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase+nOBSat, nBase-nOBSat, regRecord);
+  if( nOBSat>0 ){
+    int regPrevKey;   /* The first nOBSat columns of the previous row */
+    int addrFirst;    /* Address of the OP_IfNot opcode */
+    int addrJmp;      /* Address of the OP_Jump opcode */
+    VdbeOp *pOp;      /* Opcode that opens the sorter */
+    int nKey;         /* Number of sorting key columns, including OP_Sequence */
+    KeyInfo *pKI;     /* Original KeyInfo on the sorter table */
+
+    regPrevKey = pParse->nMem+1;
+    pParse->nMem += pSort->nOBSat;
+    nKey = nExpr - pSort->nOBSat + bSeq;
+    if( bSeq ){
+      addrFirst = sqlite3VdbeAddOp1(v, OP_IfNot, regBase+nExpr); 
+    }else{
+      addrFirst = sqlite3VdbeAddOp1(v, OP_SequenceTest, pSort->iECursor);
+    }
+    VdbeCoverage(v);
+    sqlite3VdbeAddOp3(v, OP_Compare, regPrevKey, regBase, pSort->nOBSat);
+    pOp = sqlite3VdbeGetOp(v, pSort->addrSortIndex);
+    if( pParse->db->mallocFailed ) return;
+    pOp->p2 = nKey + nData;
+    pKI = pOp->p4.pKeyInfo;
+    memset(pKI->aSortOrder, 0, pKI->nField); /* Makes OP_Jump below testable */
+    sqlite3VdbeChangeP4(v, -1, (char*)pKI, P4_KEYINFO);
+    testcase( pKI->nXField>2 );
+    pOp->p4.pKeyInfo = keyInfoFromExprList(pParse, pSort->pOrderBy, nOBSat,
+                                           pKI->nXField-1);
+    addrJmp = sqlite3VdbeCurrentAddr(v);
+    sqlite3VdbeAddOp3(v, OP_Jump, addrJmp+1, 0, addrJmp+1); VdbeCoverage(v);
+    pSort->labelBkOut = sqlite3VdbeMakeLabel(v);
+    pSort->regReturn = ++pParse->nMem;
+    sqlite3VdbeAddOp2(v, OP_Gosub, pSort->regReturn, pSort->labelBkOut);
+    sqlite3VdbeAddOp1(v, OP_ResetSorter, pSort->iECursor);
+    if( iLimit ){
+      sqlite3VdbeAddOp2(v, OP_IfNot, iLimit, pSort->labelDone);
+      VdbeCoverage(v);
+    }
+    sqlite3VdbeJumpHere(v, addrFirst);
+    sqlite3ExprCodeMove(pParse, regBase, regPrevKey, pSort->nOBSat);
+    sqlite3VdbeJumpHere(v, addrJmp);
+  }
+  if( pSort->sortFlags & SORTFLAG_UseSorter ){
+    op = OP_SorterInsert;
+  }else{
+    op = OP_IdxInsert;
+  }
+  sqlite3VdbeAddOp2(v, op, pSort->iECursor, regRecord);
+  if( iLimit ){
+    int addr;
+    int r1 = 0;
+    /* Fill the sorter until it contains LIMIT+OFFSET entries.  (The iLimit
+    ** register is initialized with value of LIMIT+OFFSET.)  After the sorter
+    ** fills up, delete the least entry in the sorter after each insert.
+    ** Thus we never hold more than the LIMIT+OFFSET rows in memory at once */
+    addr = sqlite3VdbeAddOp3(v, OP_IfNotZero, iLimit, 0, 1); VdbeCoverage(v);
+    sqlite3VdbeAddOp1(v, OP_Last, pSort->iECursor);
+    if( pSort->bOrderedInnerLoop ){
+      r1 = ++pParse->nMem;
+      sqlite3VdbeAddOp3(v, OP_Column, pSort->iECursor, nExpr, r1);
+      VdbeComment((v, "seq"));
+    }
+    sqlite3VdbeAddOp1(v, OP_Delete, pSort->iECursor);
+    if( pSort->bOrderedInnerLoop ){
+      /* If the inner loop is driven by an index such that values from
+      ** the same iteration of the inner loop are in sorted order, then
+      ** immediately jump to the next iteration of an inner loop if the
+      ** entry from the current iteration does not fit into the top
+      ** LIMIT+OFFSET entries of the sorter. */
+      int iBrk = sqlite3VdbeCurrentAddr(v) + 2;
+      sqlite3VdbeAddOp3(v, OP_Eq, regBase+nExpr, iBrk, r1);
+      sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
+      VdbeCoverage(v);
+    }
+    sqlite3VdbeJumpHere(v, addr);
+  }
+}
+
+/*
+** Add code to implement the OFFSET
+*/
+static void codeOffset(
+  Vdbe *v,          /* Generate code into this VM */
+  int iOffset,      /* Register holding the offset counter */
+  int iContinue     /* Jump here to skip the current record */
+){
+  if( iOffset>0 ){
+    sqlite3VdbeAddOp3(v, OP_IfPos, iOffset, iContinue, 1); VdbeCoverage(v);
+    VdbeComment((v, "OFFSET"));
+  }
+}
+
+/*
+** Add code that will check to make sure the N registers starting at iMem
+** form a distinct entry.  iTab is a sorting index that holds previously
+** seen combinations of the N values.  A new entry is made in iTab
+** if the current N values are new.
+**
+** A jump to addrRepeat is made and the N+1 values are popped from the
+** stack if the top N elements are not distinct.
+*/
+static void codeDistinct(
+  Parse *pParse,     /* Parsing and code generating context */
+  int iTab,          /* A sorting index used to test for distinctness */
+  int addrRepeat,    /* Jump to here if not distinct */
+  int N,             /* Number of elements */
+  int iMem           /* First element */
+){
+  Vdbe *v;
+  int r1;
+
+  v = pParse->pVdbe;
+  r1 = sqlite3GetTempReg(pParse);
+  sqlite3VdbeAddOp4Int(v, OP_Found, iTab, addrRepeat, iMem, N); VdbeCoverage(v);
+  sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, N, r1);
+  sqlite3VdbeAddOp2(v, OP_IdxInsert, iTab, r1);
+  sqlite3ReleaseTempReg(pParse, r1);
+}
+
+/*
+** This routine generates the code for the inside of the inner loop
+** of a SELECT.
+**
+** If srcTab is negative, then the pEList expressions
+** are evaluated in order to get the data for this row.  If srcTab is
+** zero or more, then data is pulled from srcTab and pEList is used only 
+** to get number columns and the datatype for each column.
+*/
+static void selectInnerLoop(
+  Parse *pParse,          /* The parser context */
+  Select *p,              /* The complete select statement being coded */
+  ExprList *pEList,       /* List of values being extracted */
+  int srcTab,             /* Pull data from this table */
+  SortCtx *pSort,         /* If not NULL, info on how to process ORDER BY */
+  DistinctCtx *pDistinct, /* If not NULL, info on how to process DISTINCT */
+  SelectDest *pDest,      /* How to dispose of the results */
+  int iContinue,          /* Jump here to continue with next row */
+  int iBreak              /* Jump here to break out of the inner loop */
+){
+  Vdbe *v = pParse->pVdbe;
+  int i;
+  int hasDistinct;        /* True if the DISTINCT keyword is present */
+  int regResult;              /* Start of memory holding result set */
+  int eDest = pDest->eDest;   /* How to dispose of results */
+  int iParm = pDest->iSDParm; /* First argument to disposal method */
+  int nResultCol;             /* Number of result columns */
+  int nPrefixReg = 0;         /* Number of extra registers before regResult */
+
+  assert( v );
+  assert( pEList!=0 );
+  hasDistinct = pDistinct ? pDistinct->eTnctType : WHERE_DISTINCT_NOOP;
+  if( pSort && pSort->pOrderBy==0 ) pSort = 0;
+  if( pSort==0 && !hasDistinct ){
+    assert( iContinue!=0 );
+    codeOffset(v, p->iOffset, iContinue);
+  }
+
+  /* Pull the requested columns.
+  */
+  nResultCol = pEList->nExpr;
+
+  if( pDest->iSdst==0 ){
+    if( pSort ){
+      nPrefixReg = pSort->pOrderBy->nExpr;
+      if( !(pSort->sortFlags & SORTFLAG_UseSorter) ) nPrefixReg++;
+      pParse->nMem += nPrefixReg;
+    }
+    pDest->iSdst = pParse->nMem+1;
+    pParse->nMem += nResultCol;
+  }else if( pDest->iSdst+nResultCol > pParse->nMem ){
+    /* This is an error condition that can result, for example, when a SELECT
+    ** on the right-hand side of an INSERT contains more result columns than
+    ** there are columns in the table on the left.  The error will be caught
+    ** and reported later.  But we need to make sure enough memory is allocated
+    ** to avoid other spurious errors in the meantime. */
+    pParse->nMem += nResultCol;
+  }
+  pDest->nSdst = nResultCol;
+  regResult = pDest->iSdst;
+  if( srcTab>=0 ){
+    for(i=0; i<nResultCol; i++){
+      sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
+      VdbeComment((v, "%s", pEList->a[i].zName));
+    }
+  }else if( eDest!=SRT_Exists ){
+    /* If the destination is an EXISTS(...) expression, the actual
+    ** values returned by the SELECT are not required.
+    */
+    u8 ecelFlags;
+    if( eDest==SRT_Mem || eDest==SRT_Output || eDest==SRT_Coroutine ){
+      ecelFlags = SQLITE_ECEL_DUP;
+    }else{
+      ecelFlags = 0;
+    }
+    sqlite3ExprCodeExprList(pParse, pEList, regResult, 0, ecelFlags);
+  }
+
+  /* If the DISTINCT keyword was present on the SELECT statement
+  ** and this row has been seen before, then do not make this row
+  ** part of the result.
+  */
+  if( hasDistinct ){
+    switch( pDistinct->eTnctType ){
+      case WHERE_DISTINCT_ORDERED: {
+        VdbeOp *pOp;            /* No longer required OpenEphemeral instr. */
+        int iJump;              /* Jump destination */
+        int regPrev;            /* Previous row content */
+
+        /* Allocate space for the previous row */
+        regPrev = pParse->nMem+1;
+        pParse->nMem += nResultCol;
+
+        /* Change the OP_OpenEphemeral coded earlier to an OP_Null
+        ** sets the MEM_Cleared bit on the first register of the
+        ** previous value.  This will cause the OP_Ne below to always
+        ** fail on the first iteration of the loop even if the first
+        ** row is all NULLs.
+        */
+        sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct);
+        pOp = sqlite3VdbeGetOp(v, pDistinct->addrTnct);
+        pOp->opcode = OP_Null;
+        pOp->p1 = 1;
+        pOp->p2 = regPrev;
+
+        iJump = sqlite3VdbeCurrentAddr(v) + nResultCol;
+        for(i=0; i<nResultCol; i++){
+          CollSeq *pColl = sqlite3ExprCollSeq(pParse, pEList->a[i].pExpr);
+          if( i<nResultCol-1 ){
+            sqlite3VdbeAddOp3(v, OP_Ne, regResult+i, iJump, regPrev+i);
+            VdbeCoverage(v);
+          }else{
+            sqlite3VdbeAddOp3(v, OP_Eq, regResult+i, iContinue, regPrev+i);
+            VdbeCoverage(v);
+           }
+          sqlite3VdbeChangeP4(v, -1, (const char *)pColl, P4_COLLSEQ);
+          sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
+        }
+        assert( sqlite3VdbeCurrentAddr(v)==iJump || pParse->db->mallocFailed );
+        sqlite3VdbeAddOp3(v, OP_Copy, regResult, regPrev, nResultCol-1);
+        break;
+      }
+
+      case WHERE_DISTINCT_UNIQUE: {
+        sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct);
+        break;
+      }
+
+      default: {
+        assert( pDistinct->eTnctType==WHERE_DISTINCT_UNORDERED );
+        codeDistinct(pParse, pDistinct->tabTnct, iContinue, nResultCol,
+                     regResult);
+        break;
+      }
+    }
+    if( pSort==0 ){
+      codeOffset(v, p->iOffset, iContinue);
+    }
+  }
+
+  switch( eDest ){
+    /* In this mode, write each query result to the key of the temporary
+    ** table iParm.
+    */
+#ifndef SQLITE_OMIT_COMPOUND_SELECT
+    case SRT_Union: {
+      int r1;
+      r1 = sqlite3GetTempReg(pParse);
+      sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1);
+      sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1);
+      sqlite3ReleaseTempReg(pParse, r1);
+      break;
+    }
+
+    /* Construct a record from the query result, but instead of
+    ** saving that record, use it as a key to delete elements from
+    ** the temporary table iParm.
+    */
+    case SRT_Except: {
+      sqlite3VdbeAddOp3(v, OP_IdxDelete, iParm, regResult, nResultCol);
+      break;
+    }
+#endif /* SQLITE_OMIT_COMPOUND_SELECT */
+
+    /* Store the result as data using a unique key.
+    */
+    case SRT_Fifo:
+    case SRT_DistFifo:
+    case SRT_Table:
+    case SRT_EphemTab: {
+      int r1 = sqlite3GetTempRange(pParse, nPrefixReg+1);
+      testcase( eDest==SRT_Table );
+      testcase( eDest==SRT_EphemTab );
+      testcase( eDest==SRT_Fifo );
+      testcase( eDest==SRT_DistFifo );
+      sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1+nPrefixReg);
+#ifndef SQLITE_OMIT_CTE
+      if( eDest==SRT_DistFifo ){
+        /* If the destination is DistFifo, then cursor (iParm+1) is open
+        ** on an ephemeral index. If the current row is already present
+        ** in the index, do not write it to the output. If not, add the
+        ** current row to the index and proceed with writing it to the
+        ** output table as well.  */
+        int addr = sqlite3VdbeCurrentAddr(v) + 4;
+        sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, addr, r1, 0);
+        VdbeCoverage(v);
+        sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm+1, r1);
+        assert( pSort==0 );
+      }
+#endif
+      if( pSort ){
+        pushOntoSorter(pParse, pSort, p, r1+nPrefixReg,regResult,1,nPrefixReg);
+      }else{
+        int r2 = sqlite3GetTempReg(pParse);
+        sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, r2);
+        sqlite3VdbeAddOp3(v, OP_Insert, iParm, r1, r2);
+        sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
+        sqlite3ReleaseTempReg(pParse, r2);
+      }
+      sqlite3ReleaseTempRange(pParse, r1, nPrefixReg+1);
+      break;
+    }
+
+#ifndef SQLITE_OMIT_SUBQUERY
+    /* If we are creating a set for an "expr IN (SELECT ...)" construct,
+    ** then there should be a single item on the stack.  Write this
+    ** item into the set table with bogus data.
+    */
+    case SRT_Set: {
+      if( pSort ){
+        /* At first glance you would think we could optimize out the
+        ** ORDER BY in this case since the order of entries in the set
+        ** does not matter.  But there might be a LIMIT clause, in which
+        ** case the order does matter */
+        pushOntoSorter(
+            pParse, pSort, p, regResult, regResult, nResultCol, nPrefixReg);
+      }else{
+        int r1 = sqlite3GetTempReg(pParse);
+        assert( sqlite3Strlen30(pDest->zAffSdst)==nResultCol );
+        sqlite3VdbeAddOp4(v, OP_MakeRecord, regResult, nResultCol, 
+            r1, pDest->zAffSdst, nResultCol);
+        sqlite3ExprCacheAffinityChange(pParse, regResult, nResultCol);
+        sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1);
+        sqlite3ReleaseTempReg(pParse, r1);
+      }
+      break;
+    }
+
+    /* If any row exist in the result set, record that fact and abort.
+    */
+    case SRT_Exists: {
+      sqlite3VdbeAddOp2(v, OP_Integer, 1, iParm);
+      /* The LIMIT clause will terminate the loop for us */
+      break;
+    }
+
+    /* If this is a scalar select that is part of an expression, then
+    ** store the results in the appropriate memory cell or array of 
+    ** memory cells and break out of the scan loop.
+    */
+    case SRT_Mem: {
+      assert( nResultCol==pDest->nSdst );
+      if( pSort ){
+        pushOntoSorter(
+            pParse, pSort, p, regResult, regResult, nResultCol, nPrefixReg);
+      }else{
+        assert( regResult==iParm );
+        /* The LIMIT clause will jump out of the loop for us */
+      }
+      break;
+    }
+#endif /* #ifndef SQLITE_OMIT_SUBQUERY */
+
+    case SRT_Coroutine:       /* Send data to a co-routine */
+    case SRT_Output: {        /* Return the results */
+      testcase( eDest==SRT_Coroutine );
+      testcase( eDest==SRT_Output );
+      if( pSort ){
+        pushOntoSorter(pParse, pSort, p, regResult, regResult, nResultCol,
+                       nPrefixReg);
+      }else if( eDest==SRT_Coroutine ){
+        sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm);
+      }else{
+        sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, nResultCol);
+        sqlite3ExprCacheAffinityChange(pParse, regResult, nResultCol);
+      }
+      break;
+    }
+
+#ifndef SQLITE_OMIT_CTE
+    /* Write the results into a priority queue that is order according to
+    ** pDest->pOrderBy (in pSO).  pDest->iSDParm (in iParm) is the cursor for an
+    ** index with pSO->nExpr+2 columns.  Build a key using pSO for the first
+    ** pSO->nExpr columns, then make sure all keys are unique by adding a
+    ** final OP_Sequence column.  The last column is the record as a blob.
+    */
+    case SRT_DistQueue:
+    case SRT_Queue: {
+      int nKey;
+      int r1, r2, r3;
+      int addrTest = 0;
+      ExprList *pSO;
+      pSO = pDest->pOrderBy;
+      assert( pSO );
+      nKey = pSO->nExpr;
+      r1 = sqlite3GetTempReg(pParse);
+      r2 = sqlite3GetTempRange(pParse, nKey+2);
+      r3 = r2+nKey+1;
+      if( eDest==SRT_DistQueue ){
+        /* If the destination is DistQueue, then cursor (iParm+1) is open
+        ** on a second ephemeral index that holds all values every previously
+        ** added to the queue. */
+        addrTest = sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, 0, 
+                                        regResult, nResultCol);
+        VdbeCoverage(v);
+      }
+      sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r3);
+      if( eDest==SRT_DistQueue ){
+        sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm+1, r3);
+        sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
+      }
+      for(i=0; i<nKey; i++){
+        sqlite3VdbeAddOp2(v, OP_SCopy,
+                          regResult + pSO->a[i].u.x.iOrderByCol - 1,
+                          r2+i);
+      }
+      sqlite3VdbeAddOp2(v, OP_Sequence, iParm, r2+nKey);
+      sqlite3VdbeAddOp3(v, OP_MakeRecord, r2, nKey+2, r1);
+      sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1);
+      if( addrTest ) sqlite3VdbeJumpHere(v, addrTest);
+      sqlite3ReleaseTempReg(pParse, r1);
+      sqlite3ReleaseTempRange(pParse, r2, nKey+2);
+      break;
+    }
+#endif /* SQLITE_OMIT_CTE */
+
+
+
+#if !defined(SQLITE_OMIT_TRIGGER)
+    /* Discard the results.  This is used for SELECT statements inside
+    ** the body of a TRIGGER.  The purpose of such selects is to call
+    ** user-defined functions that have side effects.  We do not care
+    ** about the actual results of the select.
+    */
+    default: {
+      assert( eDest==SRT_Discard );
+      break;
+    }
+#endif
+  }
+
+  /* Jump to the end of the loop if the LIMIT is reached.  Except, if
+  ** there is a sorter, in which case the sorter has already limited
+  ** the output for us.
+  */
+  if( pSort==0 && p->iLimit ){
+    sqlite3VdbeAddOp2(v, OP_DecrJumpZero, p->iLimit, iBreak); VdbeCoverage(v);
+  }
+}
+
+/*
+** Allocate a KeyInfo object sufficient for an index of N key columns and
+** X extra columns.
+*/
+SQLITE_PRIVATE KeyInfo *sqlite3KeyInfoAlloc(sqlite3 *db, int N, int X){
+  int nExtra = (N+X)*(sizeof(CollSeq*)+1);
+  KeyInfo *p = sqlite3DbMallocRawNN(db, sizeof(KeyInfo) + nExtra);
+  if( p ){
+    p->aSortOrder = (u8*)&p->aColl[N+X];
+    p->nField = (u16)N;
+    p->nXField = (u16)X;
+    p->enc = ENC(db);
+    p->db = db;
+    p->nRef = 1;
+    memset(&p[1], 0, nExtra);
+  }else{
+    sqlite3OomFault(db);
+  }
+  return p;
+}
+
+/*
+** Deallocate a KeyInfo object
+*/
+SQLITE_PRIVATE void sqlite3KeyInfoUnref(KeyInfo *p){
+  if( p ){
+    assert( p->nRef>0 );
+    p->nRef--;
+    if( p->nRef==0 ) sqlite3DbFree(p->db, p);
+  }
+}
+
+/*
+** Make a new pointer to a KeyInfo object
+*/
+SQLITE_PRIVATE KeyInfo *sqlite3KeyInfoRef(KeyInfo *p){
+  if( p ){
+    assert( p->nRef>0 );
+    p->nRef++;
+  }
+  return p;
+}
+
+#ifdef SQLITE_DEBUG
+/*
+** Return TRUE if a KeyInfo object can be change.  The KeyInfo object
+** can only be changed if this is just a single reference to the object.
+**
+** This routine is used only inside of assert() statements.
+*/
+SQLITE_PRIVATE int sqlite3KeyInfoIsWriteable(KeyInfo *p){ return p->nRef==1; }
+#endif /* SQLITE_DEBUG */
+
+/*
+** Given an expression list, generate a KeyInfo structure that records
+** the collating sequence for each expression in that expression list.
+**
+** If the ExprList is an ORDER BY or GROUP BY clause then the resulting
+** KeyInfo structure is appropriate for initializing a virtual index to
+** implement that clause.  If the ExprList is the result set of a SELECT
+** then the KeyInfo structure is appropriate for initializing a virtual
+** index to implement a DISTINCT test.
+**
+** Space to hold the KeyInfo structure is obtained from malloc.  The calling
+** function is responsible for seeing that this structure is eventually
+** freed.
+*/
+static KeyInfo *keyInfoFromExprList(
+  Parse *pParse,       /* Parsing context */
+  ExprList *pList,     /* Form the KeyInfo object from this ExprList */
+  int iStart,          /* Begin with this column of pList */
+  int nExtra           /* Add this many extra columns to the end */
+){
+  int nExpr;
+  KeyInfo *pInfo;
+  struct ExprList_item *pItem;
+  sqlite3 *db = pParse->db;
+  int i;
+
+  nExpr = pList->nExpr;
+  pInfo = sqlite3KeyInfoAlloc(db, nExpr-iStart, nExtra+1);
+  if( pInfo ){
+    assert( sqlite3KeyInfoIsWriteable(pInfo) );
+    for(i=iStart, pItem=pList->a+iStart; i<nExpr; i++, pItem++){
+      CollSeq *pColl;
+      pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
+      if( !pColl ) pColl = db->pDfltColl;
+      pInfo->aColl[i-iStart] = pColl;
+      pInfo->aSortOrder[i-iStart] = pItem->sortOrder;
+    }
+  }
+  return pInfo;
+}
+
+/*
+** Name of the connection operator, used for error messages.
+*/
+static const char *selectOpName(int id){
+  char *z;
+  switch( id ){
+    case TK_ALL:       z = "UNION ALL";   break;
+    case TK_INTERSECT: z = "INTERSECT";   break;
+    case TK_EXCEPT:    z = "EXCEPT";      break;
+    default:           z = "UNION";       break;
+  }
+  return z;
+}
+
+#ifndef SQLITE_OMIT_EXPLAIN
+/*
+** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function
+** is a no-op. Otherwise, it adds a single row of output to the EQP result,
+** where the caption is of the form:
+**
+**   "USE TEMP B-TREE FOR xxx"
+**
+** where xxx is one of "DISTINCT", "ORDER BY" or "GROUP BY". Exactly which
+** is determined by the zUsage argument.
+*/
+static void explainTempTable(Parse *pParse, const char *zUsage){
+  if( pParse->explain==2 ){
+    Vdbe *v = pParse->pVdbe;
+    char *zMsg = sqlite3MPrintf(pParse->db, "USE TEMP B-TREE FOR %s", zUsage);
+    sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC);
+  }
+}
+
+/*
+** Assign expression b to lvalue a. A second, no-op, version of this macro
+** is provided when SQLITE_OMIT_EXPLAIN is defined. This allows the code
+** in sqlite3Select() to assign values to structure member variables that
+** only exist if SQLITE_OMIT_EXPLAIN is not defined without polluting the
+** code with #ifndef directives.
+*/
+# define explainSetInteger(a, b) a = b
+
+#else
+/* No-op versions of the explainXXX() functions and macros. */
+# define explainTempTable(y,z)
+# define explainSetInteger(y,z)
+#endif
+
+#if !defined(SQLITE_OMIT_EXPLAIN) && !defined(SQLITE_OMIT_COMPOUND_SELECT)
+/*
+** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function
+** is a no-op. Otherwise, it adds a single row of output to the EQP result,
+** where the caption is of one of the two forms:
+**
+**   "COMPOSITE SUBQUERIES iSub1 and iSub2 (op)"
+**   "COMPOSITE SUBQUERIES iSub1 and iSub2 USING TEMP B-TREE (op)"
+**
+** where iSub1 and iSub2 are the integers passed as the corresponding
+** function parameters, and op is the text representation of the parameter
+** of the same name. The parameter "op" must be one of TK_UNION, TK_EXCEPT,
+** TK_INTERSECT or TK_ALL. The first form is used if argument bUseTmp is 
+** false, or the second form if it is true.
+*/
+static void explainComposite(
+  Parse *pParse,                  /* Parse context */
+  int op,                         /* One of TK_UNION, TK_EXCEPT etc. */
+  int iSub1,                      /* Subquery id 1 */
+  int iSub2,                      /* Subquery id 2 */
+  int bUseTmp                     /* True if a temp table was used */
+){
+  assert( op==TK_UNION || op==TK_EXCEPT || op==TK_INTERSECT || op==TK_ALL );
+  if( pParse->explain==2 ){
+    Vdbe *v = pParse->pVdbe;
+    char *zMsg = sqlite3MPrintf(
+        pParse->db, "COMPOUND SUBQUERIES %d AND %d %s(%s)", iSub1, iSub2,
+        bUseTmp?"USING TEMP B-TREE ":"", selectOpName(op)
+    );
+    sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC);
+  }
+}
+#else
+/* No-op versions of the explainXXX() functions and macros. */
+# define explainComposite(v,w,x,y,z)
+#endif
+
+/*
+** If the inner loop was generated using a non-null pOrderBy argument,
+** then the results were placed in a sorter.  After the loop is terminated
+** we need to run the sorter and output the results.  The following
+** routine generates the code needed to do that.
+*/
+static void generateSortTail(
+  Parse *pParse,    /* Parsing context */
+  Select *p,        /* The SELECT statement */
+  SortCtx *pSort,   /* Information on the ORDER BY clause */
+  int nColumn,      /* Number of columns of data */
+  SelectDest *pDest /* Write the sorted results here */
+){
+  Vdbe *v = pParse->pVdbe;                     /* The prepared statement */
+  int addrBreak = pSort->labelDone;            /* Jump here to exit loop */
+  int addrContinue = sqlite3VdbeMakeLabel(v);  /* Jump here for next cycle */
+  int addr;
+  int addrOnce = 0;
+  int iTab;
+  ExprList *pOrderBy = pSort->pOrderBy;
+  int eDest = pDest->eDest;
+  int iParm = pDest->iSDParm;
+  int regRow;
+  int regRowid;
+  int nKey;
+  int iSortTab;                   /* Sorter cursor to read from */
+  int nSortData;                  /* Trailing values to read from sorter */
+  int i;
+  int bSeq;                       /* True if sorter record includes seq. no. */
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+  struct ExprList_item *aOutEx = p->pEList->a;
+#endif
+
+  assert( addrBreak<0 );
+  if( pSort->labelBkOut ){
+    sqlite3VdbeAddOp2(v, OP_Gosub, pSort->regReturn, pSort->labelBkOut);
+    sqlite3VdbeGoto(v, addrBreak);
+    sqlite3VdbeResolveLabel(v, pSort->labelBkOut);
+  }
+  iTab = pSort->iECursor;
+  if( eDest==SRT_Output || eDest==SRT_Coroutine || eDest==SRT_Mem ){
+    regRowid = 0;
+    regRow = pDest->iSdst;
+    nSortData = nColumn;
+  }else{
+    regRowid = sqlite3GetTempReg(pParse);
+    regRow = sqlite3GetTempRange(pParse, nColumn);
+    nSortData = nColumn;
+  }
+  nKey = pOrderBy->nExpr - pSort->nOBSat;
+  if( pSort->sortFlags & SORTFLAG_UseSorter ){
+    int regSortOut = ++pParse->nMem;
+    iSortTab = pParse->nTab++;
+    if( pSort->labelBkOut ){
+      addrOnce = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
+    }
+    sqlite3VdbeAddOp3(v, OP_OpenPseudo, iSortTab, regSortOut, nKey+1+nSortData);
+    if( addrOnce ) sqlite3VdbeJumpHere(v, addrOnce);
+    addr = 1 + sqlite3VdbeAddOp2(v, OP_SorterSort, iTab, addrBreak);
+    VdbeCoverage(v);
+    codeOffset(v, p->iOffset, addrContinue);
+    sqlite3VdbeAddOp3(v, OP_SorterData, iTab, regSortOut, iSortTab);
+    bSeq = 0;
+  }else{
+    addr = 1 + sqlite3VdbeAddOp2(v, OP_Sort, iTab, addrBreak); VdbeCoverage(v);
+    codeOffset(v, p->iOffset, addrContinue);
+    iSortTab = iTab;
+    bSeq = 1;
+  }
+  for(i=0; i<nSortData; i++){
+    sqlite3VdbeAddOp3(v, OP_Column, iSortTab, nKey+bSeq+i, regRow+i);
+    VdbeComment((v, "%s", aOutEx[i].zName ? aOutEx[i].zName : aOutEx[i].zSpan));
+  }
+  switch( eDest ){
+    case SRT_EphemTab: {
+      sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, regRowid);
+      sqlite3VdbeAddOp3(v, OP_Insert, iParm, regRow, regRowid);
+      sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
+      break;
+    }
+#ifndef SQLITE_OMIT_SUBQUERY
+    case SRT_Set: {
+      assert( nColumn==sqlite3Strlen30(pDest->zAffSdst) );
+      sqlite3VdbeAddOp4(v, OP_MakeRecord, regRow, nColumn, regRowid,
+                        pDest->zAffSdst, nColumn);
+      sqlite3ExprCacheAffinityChange(pParse, regRow, nColumn);
+      sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, regRowid);
+      break;
+    }
+    case SRT_Mem: {
+      /* The LIMIT clause will terminate the loop for us */
+      break;
+    }
+#endif
+    default: {
+      assert( eDest==SRT_Output || eDest==SRT_Coroutine ); 
+      testcase( eDest==SRT_Output );
+      testcase( eDest==SRT_Coroutine );
+      if( eDest==SRT_Output ){
+        sqlite3VdbeAddOp2(v, OP_ResultRow, pDest->iSdst, nColumn);
+        sqlite3ExprCacheAffinityChange(pParse, pDest->iSdst, nColumn);
+      }else{
+        sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm);
+      }
+      break;
+    }
+  }
+  if( regRowid ){
+    if( eDest==SRT_Set ){
+      sqlite3ReleaseTempRange(pParse, regRow, nColumn);
+    }else{
+      sqlite3ReleaseTempReg(pParse, regRow);
+    }
+    sqlite3ReleaseTempReg(pParse, regRowid);
+  }
+  /* The bottom of the loop
+  */
+  sqlite3VdbeResolveLabel(v, addrContinue);
+  if( pSort->sortFlags & SORTFLAG_UseSorter ){
+    sqlite3VdbeAddOp2(v, OP_SorterNext, iTab, addr); VdbeCoverage(v);
+  }else{
+    sqlite3VdbeAddOp2(v, OP_Next, iTab, addr); VdbeCoverage(v);
+  }
+  if( pSort->regReturn ) sqlite3VdbeAddOp1(v, OP_Return, pSort->regReturn);
+  sqlite3VdbeResolveLabel(v, addrBreak);
+}
+
+/*
+** Return a pointer to a string containing the 'declaration type' of the
+** expression pExpr. The string may be treated as static by the caller.
+**
+** Also try to estimate the size of the returned value and return that
+** result in *pEstWidth.
+**
+** The declaration type is the exact datatype definition extracted from the
+** original CREATE TABLE statement if the expression is a column. The
+** declaration type for a ROWID field is INTEGER. Exactly when an expression
+** is considered a column can be complex in the presence of subqueries. The
+** result-set expression in all of the following SELECT statements is 
+** considered a column by this function.
+**
+**   SELECT col FROM tbl;
+**   SELECT (SELECT col FROM tbl;
+**   SELECT (SELECT col FROM tbl);
+**   SELECT abc FROM (SELECT col AS abc FROM tbl);
+** 
+** The declaration type for any expression other than a column is NULL.
+**
+** This routine has either 3 or 6 parameters depending on whether or not
+** the SQLITE_ENABLE_COLUMN_METADATA compile-time option is used.
+*/
+#ifdef SQLITE_ENABLE_COLUMN_METADATA
+# define columnType(A,B,C,D,E,F) columnTypeImpl(A,B,C,D,E,F)
+#else /* if !defined(SQLITE_ENABLE_COLUMN_METADATA) */
+# define columnType(A,B,C,D,E,F) columnTypeImpl(A,B,F)
+#endif
+static const char *columnTypeImpl(
+  NameContext *pNC, 
+  Expr *pExpr,
+#ifdef SQLITE_ENABLE_COLUMN_METADATA
+  const char **pzOrigDb,
+  const char **pzOrigTab,
+  const char **pzOrigCol,
+#endif
+  u8 *pEstWidth
+){
+  char const *zType = 0;
+  int j;
+  u8 estWidth = 1;
+#ifdef SQLITE_ENABLE_COLUMN_METADATA
+  char const *zOrigDb = 0;
+  char const *zOrigTab = 0;
+  char const *zOrigCol = 0;
+#endif
+
+  assert( pExpr!=0 );
+  assert( pNC->pSrcList!=0 );
+  switch( pExpr->op ){
+    case TK_AGG_COLUMN:
+    case TK_COLUMN: {
+      /* The expression is a column. Locate the table the column is being
+      ** extracted from in NameContext.pSrcList. This table may be real
+      ** database table or a subquery.
+      */
+      Table *pTab = 0;            /* Table structure column is extracted from */
+      Select *pS = 0;             /* Select the column is extracted from */
+      int iCol = pExpr->iColumn;  /* Index of column in pTab */
+      testcase( pExpr->op==TK_AGG_COLUMN );
+      testcase( pExpr->op==TK_COLUMN );
+      while( pNC && !pTab ){
+        SrcList *pTabList = pNC->pSrcList;
+        for(j=0;j<pTabList->nSrc && pTabList->a[j].iCursor!=pExpr->iTable;j++);
+        if( j<pTabList->nSrc ){
+          pTab = pTabList->a[j].pTab;
+          pS = pTabList->a[j].pSelect;
+        }else{
+          pNC = pNC->pNext;
+        }
+      }
+
+      if( pTab==0 ){
+        /* At one time, code such as "SELECT new.x" within a trigger would
+        ** cause this condition to run.  Since then, we have restructured how
+        ** trigger code is generated and so this condition is no longer 
+        ** possible. However, it can still be true for statements like
+        ** the following:
+        **
+        **   CREATE TABLE t1(col INTEGER);
+        **   SELECT (SELECT t1.col) FROM FROM t1;
+        **
+        ** when columnType() is called on the expression "t1.col" in the 
+        ** sub-select. In this case, set the column type to NULL, even
+        ** though it should really be "INTEGER".
+        **
+        ** This is not a problem, as the column type of "t1.col" is never
+        ** used. When columnType() is called on the expression 
+        ** "(SELECT t1.col)", the correct type is returned (see the TK_SELECT
+        ** branch below.  */
+        break;
+      }
+
+      assert( pTab && pExpr->pTab==pTab );
+      if( pS ){
+        /* The "table" is actually a sub-select or a view in the FROM clause
+        ** of the SELECT statement. Return the declaration type and origin
+        ** data for the result-set column of the sub-select.
+        */
+        if( iCol>=0 && ALWAYS(iCol<pS->pEList->nExpr) ){
+          /* If iCol is less than zero, then the expression requests the
+          ** rowid of the sub-select or view. This expression is legal (see 
+          ** test case misc2.2.2) - it always evaluates to NULL.
+          **
+          ** The ALWAYS() is because iCol>=pS->pEList->nExpr will have been
+          ** caught already by name resolution.
+          */
+          NameContext sNC;
+          Expr *p = pS->pEList->a[iCol].pExpr;
+          sNC.pSrcList = pS->pSrc;
+          sNC.pNext = pNC;
+          sNC.pParse = pNC->pParse;
+          zType = columnType(&sNC, p,&zOrigDb,&zOrigTab,&zOrigCol, &estWidth); 
+        }
+      }else if( pTab->pSchema ){
+        /* A real table */
+        assert( !pS );
+        if( iCol<0 ) iCol = pTab->iPKey;
+        assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) );
+#ifdef SQLITE_ENABLE_COLUMN_METADATA
+        if( iCol<0 ){
+          zType = "INTEGER";
+          zOrigCol = "rowid";
+        }else{
+          zOrigCol = pTab->aCol[iCol].zName;
+          zType = sqlite3ColumnType(&pTab->aCol[iCol],0);
+          estWidth = pTab->aCol[iCol].szEst;
+        }
+        zOrigTab = pTab->zName;
+        if( pNC->pParse ){
+          int iDb = sqlite3SchemaToIndex(pNC->pParse->db, pTab->pSchema);
+          zOrigDb = pNC->pParse->db->aDb[iDb].zDbSName;
+        }
+#else
+        if( iCol<0 ){
+          zType = "INTEGER";
+        }else{
+          zType = sqlite3ColumnType(&pTab->aCol[iCol],0);
+          estWidth = pTab->aCol[iCol].szEst;
+        }
+#endif
+      }
+      break;
+    }
+#ifndef SQLITE_OMIT_SUBQUERY
+    case TK_SELECT: {
+      /* The expression is a sub-select. Return the declaration type and
+      ** origin info for the single column in the result set of the SELECT
+      ** statement.
+      */
+      NameContext sNC;
+      Select *pS = pExpr->x.pSelect;
+      Expr *p = pS->pEList->a[0].pExpr;
+      assert( ExprHasProperty(pExpr, EP_xIsSelect) );
+      sNC.pSrcList = pS->pSrc;
+      sNC.pNext = pNC;
+      sNC.pParse = pNC->pParse;
+      zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol, &estWidth); 
+      break;
+    }
+#endif
+  }
+
+#ifdef SQLITE_ENABLE_COLUMN_METADATA  
+  if( pzOrigDb ){
+    assert( pzOrigTab && pzOrigCol );
+    *pzOrigDb = zOrigDb;
+    *pzOrigTab = zOrigTab;
+    *pzOrigCol = zOrigCol;
+  }
+#endif
+  if( pEstWidth ) *pEstWidth = estWidth;
+  return zType;
+}
+
+/*
+** Generate code that will tell the VDBE the declaration types of columns
+** in the result set.
+*/
+static void generateColumnTypes(
+  Parse *pParse,      /* Parser context */
+  SrcList *pTabList,  /* List of tables */
+  ExprList *pEList    /* Expressions defining the result set */
+){
+#ifndef SQLITE_OMIT_DECLTYPE
+  Vdbe *v = pParse->pVdbe;
+  int i;
+  NameContext sNC;
+  sNC.pSrcList = pTabList;
+  sNC.pParse = pParse;
+  for(i=0; i<pEList->nExpr; i++){
+    Expr *p = pEList->a[i].pExpr;
+    const char *zType;
+#ifdef SQLITE_ENABLE_COLUMN_METADATA
+    const char *zOrigDb = 0;
+    const char *zOrigTab = 0;
+    const char *zOrigCol = 0;
+    zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol, 0);
+
+    /* The vdbe must make its own copy of the column-type and other 
+    ** column specific strings, in case the schema is reset before this
+    ** virtual machine is deleted.
+    */
+    sqlite3VdbeSetColName(v, i, COLNAME_DATABASE, zOrigDb, SQLITE_TRANSIENT);
+    sqlite3VdbeSetColName(v, i, COLNAME_TABLE, zOrigTab, SQLITE_TRANSIENT);
+    sqlite3VdbeSetColName(v, i, COLNAME_COLUMN, zOrigCol, SQLITE_TRANSIENT);
+#else
+    zType = columnType(&sNC, p, 0, 0, 0, 0);
+#endif
+    sqlite3VdbeSetColName(v, i, COLNAME_DECLTYPE, zType, SQLITE_TRANSIENT);
+  }
+#endif /* !defined(SQLITE_OMIT_DECLTYPE) */
+}
+
+/*
+** Generate code that will tell the VDBE the names of columns
+** in the result set.  This information is used to provide the
+** azCol[] values in the callback.
+*/
+static void generateColumnNames(
+  Parse *pParse,      /* Parser context */
+  SrcList *pTabList,  /* List of tables */
+  ExprList *pEList    /* Expressions defining the result set */
+){
+  Vdbe *v = pParse->pVdbe;
+  int i, j;
+  sqlite3 *db = pParse->db;
+  int fullNames, shortNames;
+
+#ifndef SQLITE_OMIT_EXPLAIN
+  /* If this is an EXPLAIN, skip this step */
+  if( pParse->explain ){
+    return;
+  }
+#endif
+
+  if( pParse->colNamesSet || db->mallocFailed ) return;
+  assert( v!=0 );
+  assert( pTabList!=0 );
+  pParse->colNamesSet = 1;
+  fullNames = (db->flags & SQLITE_FullColNames)!=0;
+  shortNames = (db->flags & SQLITE_ShortColNames)!=0;
+  sqlite3VdbeSetNumCols(v, pEList->nExpr);
+  for(i=0; i<pEList->nExpr; i++){
+    Expr *p;
+    p = pEList->a[i].pExpr;
+    if( NEVER(p==0) ) continue;
+    if( pEList->a[i].zName ){
+      char *zName = pEList->a[i].zName;
+      sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_TRANSIENT);
+    }else if( p->op==TK_COLUMN || p->op==TK_AGG_COLUMN ){
+      Table *pTab;
+      char *zCol;
+      int iCol = p->iColumn;
+      for(j=0; ALWAYS(j<pTabList->nSrc); j++){
+        if( pTabList->a[j].iCursor==p->iTable ) break;
+      }
+      assert( j<pTabList->nSrc );
+      pTab = pTabList->a[j].pTab;
+      if( iCol<0 ) iCol = pTab->iPKey;
+      assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) );
+      if( iCol<0 ){
+        zCol = "rowid";
+      }else{
+        zCol = pTab->aCol[iCol].zName;
+      }
+      if( !shortNames && !fullNames ){
+        sqlite3VdbeSetColName(v, i, COLNAME_NAME, 
+            sqlite3DbStrDup(db, pEList->a[i].zSpan), SQLITE_DYNAMIC);
+      }else if( fullNames ){
+        char *zName = 0;
+        zName = sqlite3MPrintf(db, "%s.%s", pTab->zName, zCol);
+        sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_DYNAMIC);
+      }else{
+        sqlite3VdbeSetColName(v, i, COLNAME_NAME, zCol, SQLITE_TRANSIENT);
+      }
+    }else{
+      const char *z = pEList->a[i].zSpan;
+      z = z==0 ? sqlite3MPrintf(db, "column%d", i+1) : sqlite3DbStrDup(db, z);
+      sqlite3VdbeSetColName(v, i, COLNAME_NAME, z, SQLITE_DYNAMIC);
+    }
+  }
+  generateColumnTypes(pParse, pTabList, pEList);
+}
+
+/*
+** Given an expression list (which is really the list of expressions
+** that form the result set of a SELECT statement) compute appropriate
+** column names for a table that would hold the expression list.
+**
+** All column names will be unique.
+**
+** Only the column names are computed.  Column.zType, Column.zColl,
+** and other fields of Column are zeroed.
+**
+** Return SQLITE_OK on success.  If a memory allocation error occurs,
+** store NULL in *paCol and 0 in *pnCol and return SQLITE_NOMEM.
+*/
+SQLITE_PRIVATE int sqlite3ColumnsFromExprList(
+  Parse *pParse,          /* Parsing context */
+  ExprList *pEList,       /* Expr list from which to derive column names */
+  i16 *pnCol,             /* Write the number of columns here */
+  Column **paCol          /* Write the new column list here */
+){
+  sqlite3 *db = pParse->db;   /* Database connection */
+  int i, j;                   /* Loop counters */
+  u32 cnt;                    /* Index added to make the name unique */
+  Column *aCol, *pCol;        /* For looping over result columns */
+  int nCol;                   /* Number of columns in the result set */
+  Expr *p;                    /* Expression for a single result column */
+  char *zName;                /* Column name */
+  int nName;                  /* Size of name in zName[] */
+  Hash ht;                    /* Hash table of column names */
+
+  sqlite3HashInit(&ht);
+  if( pEList ){
+    nCol = pEList->nExpr;
+    aCol = sqlite3DbMallocZero(db, sizeof(aCol[0])*nCol);
+    testcase( aCol==0 );
+  }else{
+    nCol = 0;
+    aCol = 0;
+  }
+  assert( nCol==(i16)nCol );
+  *pnCol = nCol;
+  *paCol = aCol;
+
+  for(i=0, pCol=aCol; i<nCol && !db->mallocFailed; i++, pCol++){
+    /* Get an appropriate name for the column
+    */
+    p = sqlite3ExprSkipCollate(pEList->a[i].pExpr);
+    if( (zName = pEList->a[i].zName)!=0 ){
+      /* If the column contains an "AS <name>" phrase, use <name> as the name */
+    }else{
+      Expr *pColExpr = p;  /* The expression that is the result column name */
+      Table *pTab;         /* Table associated with this expression */
+      while( pColExpr->op==TK_DOT ){
+        pColExpr = pColExpr->pRight;
+        assert( pColExpr!=0 );
+      }
+      if( pColExpr->op==TK_COLUMN && ALWAYS(pColExpr->pTab!=0) ){
+        /* For columns use the column name name */
+        int iCol = pColExpr->iColumn;
+        pTab = pColExpr->pTab;
+        if( iCol<0 ) iCol = pTab->iPKey;
+        zName = iCol>=0 ? pTab->aCol[iCol].zName : "rowid";
+      }else if( pColExpr->op==TK_ID ){
+        assert( !ExprHasProperty(pColExpr, EP_IntValue) );
+        zName = pColExpr->u.zToken;
+      }else{
+        /* Use the original text of the column expression as its name */
+        zName = pEList->a[i].zSpan;
+      }
+    }
+    zName = sqlite3MPrintf(db, "%s", zName);
+
+    /* Make sure the column name is unique.  If the name is not unique,
+    ** append an integer to the name so that it becomes unique.
+    */
+    cnt = 0;
+    while( zName && sqlite3HashFind(&ht, zName)!=0 ){
+      nName = sqlite3Strlen30(zName);
+      if( nName>0 ){
+        for(j=nName-1; j>0 && sqlite3Isdigit(zName[j]); j--){}
+        if( zName[j]==':' ) nName = j;
+      }
+      zName = sqlite3MPrintf(db, "%.*z:%u", nName, zName, ++cnt);
+      if( cnt>3 ) sqlite3_randomness(sizeof(cnt), &cnt);
+    }
+    pCol->zName = zName;
+    sqlite3ColumnPropertiesFromName(0, pCol);
+    if( zName && sqlite3HashInsert(&ht, zName, pCol)==pCol ){
+      sqlite3OomFault(db);
+    }
+  }
+  sqlite3HashClear(&ht);
+  if( db->mallocFailed ){
+    for(j=0; j<i; j++){
+      sqlite3DbFree(db, aCol[j].zName);
+    }
+    sqlite3DbFree(db, aCol);
+    *paCol = 0;
+    *pnCol = 0;
+    return SQLITE_NOMEM_BKPT;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Add type and collation information to a column list based on
+** a SELECT statement.
+** 
+** The column list presumably came from selectColumnNamesFromExprList().
+** The column list has only names, not types or collations.  This
+** routine goes through and adds the types and collations.
+**
+** This routine requires that all identifiers in the SELECT
+** statement be resolved.
+*/
+SQLITE_PRIVATE void sqlite3SelectAddColumnTypeAndCollation(
+  Parse *pParse,        /* Parsing contexts */
+  Table *pTab,          /* Add column type information to this table */
+  Select *pSelect       /* SELECT used to determine types and collations */
+){
+  sqlite3 *db = pParse->db;
+  NameContext sNC;
+  Column *pCol;
+  CollSeq *pColl;
+  int i;
+  Expr *p;
+  struct ExprList_item *a;
+  u64 szAll = 0;
+
+  assert( pSelect!=0 );
+  assert( (pSelect->selFlags & SF_Resolved)!=0 );
+  assert( pTab->nCol==pSelect->pEList->nExpr || db->mallocFailed );
+  if( db->mallocFailed ) return;
+  memset(&sNC, 0, sizeof(sNC));
+  sNC.pSrcList = pSelect->pSrc;
+  a = pSelect->pEList->a;
+  for(i=0, pCol=pTab->aCol; i<pTab->nCol; i++, pCol++){
+    const char *zType;
+    int n, m;
+    p = a[i].pExpr;
+    zType = columnType(&sNC, p, 0, 0, 0, &pCol->szEst);
+    szAll += pCol->szEst;
+    pCol->affinity = sqlite3ExprAffinity(p);
+    if( zType && (m = sqlite3Strlen30(zType))>0 ){
+      n = sqlite3Strlen30(pCol->zName);
+      pCol->zName = sqlite3DbReallocOrFree(db, pCol->zName, n+m+2);
+      if( pCol->zName ){
+        memcpy(&pCol->zName[n+1], zType, m+1);
+        pCol->colFlags |= COLFLAG_HASTYPE;
+      }
+    }
+    if( pCol->affinity==0 ) pCol->affinity = SQLITE_AFF_BLOB;
+    pColl = sqlite3ExprCollSeq(pParse, p);
+    if( pColl && pCol->zColl==0 ){
+      pCol->zColl = sqlite3DbStrDup(db, pColl->zName);
+    }
+  }
+  pTab->szTabRow = sqlite3LogEst(szAll*4);
+}
+
+/*
+** Given a SELECT statement, generate a Table structure that describes
+** the result set of that SELECT.
+*/
+SQLITE_PRIVATE Table *sqlite3ResultSetOfSelect(Parse *pParse, Select *pSelect){
+  Table *pTab;
+  sqlite3 *db = pParse->db;
+  int savedFlags;
+
+  savedFlags = db->flags;
+  db->flags &= ~SQLITE_FullColNames;
+  db->flags |= SQLITE_ShortColNames;
+  sqlite3SelectPrep(pParse, pSelect, 0);
+  if( pParse->nErr ) return 0;
+  while( pSelect->pPrior ) pSelect = pSelect->pPrior;
+  db->flags = savedFlags;
+  pTab = sqlite3DbMallocZero(db, sizeof(Table) );
+  if( pTab==0 ){
+    return 0;
+  }
+  /* The sqlite3ResultSetOfSelect() is only used n contexts where lookaside
+  ** is disabled */
+  assert( db->lookaside.bDisable );
+  pTab->nRef = 1;
+  pTab->zName = 0;
+  pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) );
+  sqlite3ColumnsFromExprList(pParse, pSelect->pEList, &pTab->nCol, &pTab->aCol);
+  sqlite3SelectAddColumnTypeAndCollation(pParse, pTab, pSelect);
+  pTab->iPKey = -1;
+  if( db->mallocFailed ){
+    sqlite3DeleteTable(db, pTab);
+    return 0;
+  }
+  return pTab;
+}
+
+/*
+** Get a VDBE for the given parser context.  Create a new one if necessary.
+** If an error occurs, return NULL and leave a message in pParse.
+*/
+static SQLITE_NOINLINE Vdbe *allocVdbe(Parse *pParse){
+  Vdbe *v = pParse->pVdbe = sqlite3VdbeCreate(pParse);
+  if( v ) sqlite3VdbeAddOp2(v, OP_Init, 0, 1);
+  if( pParse->pToplevel==0
+   && OptimizationEnabled(pParse->db,SQLITE_FactorOutConst)
+  ){
+    pParse->okConstFactor = 1;
+  }
+  return v;
+}
+SQLITE_PRIVATE Vdbe *sqlite3GetVdbe(Parse *pParse){
+  Vdbe *v = pParse->pVdbe;
+  return v ? v : allocVdbe(pParse);
+}
+
+
+/*
+** Compute the iLimit and iOffset fields of the SELECT based on the
+** pLimit and pOffset expressions.  pLimit and pOffset hold the expressions
+** that appear in the original SQL statement after the LIMIT and OFFSET
+** keywords.  Or NULL if those keywords are omitted. iLimit and iOffset 
+** are the integer memory register numbers for counters used to compute 
+** the limit and offset.  If there is no limit and/or offset, then 
+** iLimit and iOffset are negative.
+**
+** This routine changes the values of iLimit and iOffset only if
+** a limit or offset is defined by pLimit and pOffset.  iLimit and
+** iOffset should have been preset to appropriate default values (zero)
+** prior to calling this routine.
+**
+** The iOffset register (if it exists) is initialized to the value
+** of the OFFSET.  The iLimit register is initialized to LIMIT.  Register
+** iOffset+1 is initialized to LIMIT+OFFSET.
+**
+** Only if pLimit!=0 or pOffset!=0 do the limit registers get
+** redefined.  The UNION ALL operator uses this property to force
+** the reuse of the same limit and offset registers across multiple
+** SELECT statements.
+*/
+static void computeLimitRegisters(Parse *pParse, Select *p, int iBreak){
+  Vdbe *v = 0;
+  int iLimit = 0;
+  int iOffset;
+  int n;
+  if( p->iLimit ) return;
+
+  /* 
+  ** "LIMIT -1" always shows all rows.  There is some
+  ** controversy about what the correct behavior should be.
+  ** The current implementation interprets "LIMIT 0" to mean
+  ** no rows.
+  */
+  sqlite3ExprCacheClear(pParse);
+  assert( p->pOffset==0 || p->pLimit!=0 );
+  if( p->pLimit ){
+    p->iLimit = iLimit = ++pParse->nMem;
+    v = sqlite3GetVdbe(pParse);
+    assert( v!=0 );
+    if( sqlite3ExprIsInteger(p->pLimit, &n) ){
+      sqlite3VdbeAddOp2(v, OP_Integer, n, iLimit);
+      VdbeComment((v, "LIMIT counter"));
+      if( n==0 ){
+        sqlite3VdbeGoto(v, iBreak);
+      }else if( n>=0 && p->nSelectRow>sqlite3LogEst((u64)n) ){
+        p->nSelectRow = sqlite3LogEst((u64)n);
+        p->selFlags |= SF_FixedLimit;
+      }
+    }else{
+      sqlite3ExprCode(pParse, p->pLimit, iLimit);
+      sqlite3VdbeAddOp1(v, OP_MustBeInt, iLimit); VdbeCoverage(v);
+      VdbeComment((v, "LIMIT counter"));
+      sqlite3VdbeAddOp2(v, OP_IfNot, iLimit, iBreak); VdbeCoverage(v);
+    }
+    if( p->pOffset ){
+      p->iOffset = iOffset = ++pParse->nMem;
+      pParse->nMem++;   /* Allocate an extra register for limit+offset */
+      sqlite3ExprCode(pParse, p->pOffset, iOffset);
+      sqlite3VdbeAddOp1(v, OP_MustBeInt, iOffset); VdbeCoverage(v);
+      VdbeComment((v, "OFFSET counter"));
+      sqlite3VdbeAddOp3(v, OP_OffsetLimit, iLimit, iOffset+1, iOffset);
+      VdbeComment((v, "LIMIT+OFFSET"));
+    }
+  }
+}
+
+#ifndef SQLITE_OMIT_COMPOUND_SELECT
+/*
+** Return the appropriate collating sequence for the iCol-th column of
+** the result set for the compound-select statement "p".  Return NULL if
+** the column has no default collating sequence.
+**
+** The collating sequence for the compound select is taken from the
+** left-most term of the select that has a collating sequence.
+*/
+static CollSeq *multiSelectCollSeq(Parse *pParse, Select *p, int iCol){
+  CollSeq *pRet;
+  if( p->pPrior ){
+    pRet = multiSelectCollSeq(pParse, p->pPrior, iCol);
+  }else{
+    pRet = 0;
+  }
+  assert( iCol>=0 );
+  /* iCol must be less than p->pEList->nExpr.  Otherwise an error would
+  ** have been thrown during name resolution and we would not have gotten
+  ** this far */
+  if( pRet==0 && ALWAYS(iCol<p->pEList->nExpr) ){
+    pRet = sqlite3ExprCollSeq(pParse, p->pEList->a[iCol].pExpr);
+  }
+  return pRet;
+}
+
+/*
+** The select statement passed as the second parameter is a compound SELECT
+** with an ORDER BY clause. This function allocates and returns a KeyInfo
+** structure suitable for implementing the ORDER BY.
+**
+** Space to hold the KeyInfo structure is obtained from malloc. The calling
+** function is responsible for ensuring that this structure is eventually
+** freed.
+*/
+static KeyInfo *multiSelectOrderByKeyInfo(Parse *pParse, Select *p, int nExtra){
+  ExprList *pOrderBy = p->pOrderBy;
+  int nOrderBy = p->pOrderBy->nExpr;
+  sqlite3 *db = pParse->db;
+  KeyInfo *pRet = sqlite3KeyInfoAlloc(db, nOrderBy+nExtra, 1);
+  if( pRet ){
+    int i;
+    for(i=0; i<nOrderBy; i++){
+      struct ExprList_item *pItem = &pOrderBy->a[i];
+      Expr *pTerm = pItem->pExpr;
+      CollSeq *pColl;
+
+      if( pTerm->flags & EP_Collate ){
+        pColl = sqlite3ExprCollSeq(pParse, pTerm);
+      }else{
+        pColl = multiSelectCollSeq(pParse, p, pItem->u.x.iOrderByCol-1);
+        if( pColl==0 ) pColl = db->pDfltColl;
+        pOrderBy->a[i].pExpr =
+          sqlite3ExprAddCollateString(pParse, pTerm, pColl->zName);
+      }
+      assert( sqlite3KeyInfoIsWriteable(pRet) );
+      pRet->aColl[i] = pColl;
+      pRet->aSortOrder[i] = pOrderBy->a[i].sortOrder;
+    }
+  }
+
+  return pRet;
+}
+
+#ifndef SQLITE_OMIT_CTE
+/*
+** This routine generates VDBE code to compute the content of a WITH RECURSIVE
+** query of the form:
+**
+**   <recursive-table> AS (<setup-query> UNION [ALL] <recursive-query>)
+**                         \___________/             \_______________/
+**                           p->pPrior                      p
+**
+**
+** There is exactly one reference to the recursive-table in the FROM clause
+** of recursive-query, marked with the SrcList->a[].fg.isRecursive flag.
+**
+** The setup-query runs once to generate an initial set of rows that go
+** into a Queue table.  Rows are extracted from the Queue table one by
+** one.  Each row extracted from Queue is output to pDest.  Then the single
+** extracted row (now in the iCurrent table) becomes the content of the
+** recursive-table for a recursive-query run.  The output of the recursive-query
+** is added back into the Queue table.  Then another row is extracted from Queue
+** and the iteration continues until the Queue table is empty.
+**
+** If the compound query operator is UNION then no duplicate rows are ever
+** inserted into the Queue table.  The iDistinct table keeps a copy of all rows
+** that have ever been inserted into Queue and causes duplicates to be
+** discarded.  If the operator is UNION ALL, then duplicates are allowed.
+** 
+** If the query has an ORDER BY, then entries in the Queue table are kept in
+** ORDER BY order and the first entry is extracted for each cycle.  Without
+** an ORDER BY, the Queue table is just a FIFO.
+**
+** If a LIMIT clause is provided, then the iteration stops after LIMIT rows
+** have been output to pDest.  A LIMIT of zero means to output no rows and a
+** negative LIMIT means to output all rows.  If there is also an OFFSET clause
+** with a positive value, then the first OFFSET outputs are discarded rather
+** than being sent to pDest.  The LIMIT count does not begin until after OFFSET
+** rows have been skipped.
+*/
+static void generateWithRecursiveQuery(
+  Parse *pParse,        /* Parsing context */
+  Select *p,            /* The recursive SELECT to be coded */
+  SelectDest *pDest     /* What to do with query results */
+){
+  SrcList *pSrc = p->pSrc;      /* The FROM clause of the recursive query */
+  int nCol = p->pEList->nExpr;  /* Number of columns in the recursive table */
+  Vdbe *v = pParse->pVdbe;      /* The prepared statement under construction */
+  Select *pSetup = p->pPrior;   /* The setup query */
+  int addrTop;                  /* Top of the loop */
+  int addrCont, addrBreak;      /* CONTINUE and BREAK addresses */
+  int iCurrent = 0;             /* The Current table */
+  int regCurrent;               /* Register holding Current table */
+  int iQueue;                   /* The Queue table */
+  int iDistinct = 0;            /* To ensure unique results if UNION */
+  int eDest = SRT_Fifo;         /* How to write to Queue */
+  SelectDest destQueue;         /* SelectDest targetting the Queue table */
+  int i;                        /* Loop counter */
+  int rc;                       /* Result code */
+  ExprList *pOrderBy;           /* The ORDER BY clause */
+  Expr *pLimit, *pOffset;       /* Saved LIMIT and OFFSET */
+  int regLimit, regOffset;      /* Registers used by LIMIT and OFFSET */
+
+  /* Obtain authorization to do a recursive query */
+  if( sqlite3AuthCheck(pParse, SQLITE_RECURSIVE, 0, 0, 0) ) return;
+
+  /* Process the LIMIT and OFFSET clauses, if they exist */
+  addrBreak = sqlite3VdbeMakeLabel(v);
+  computeLimitRegisters(pParse, p, addrBreak);
+  pLimit = p->pLimit;
+  pOffset = p->pOffset;
+  regLimit = p->iLimit;
+  regOffset = p->iOffset;
+  p->pLimit = p->pOffset = 0;
+  p->iLimit = p->iOffset = 0;
+  pOrderBy = p->pOrderBy;
+
+  /* Locate the cursor number of the Current table */
+  for(i=0; ALWAYS(i<pSrc->nSrc); i++){
+    if( pSrc->a[i].fg.isRecursive ){
+      iCurrent = pSrc->a[i].iCursor;
+      break;
+    }
+  }
+
+  /* Allocate cursors numbers for Queue and Distinct.  The cursor number for
+  ** the Distinct table must be exactly one greater than Queue in order
+  ** for the SRT_DistFifo and SRT_DistQueue destinations to work. */
+  iQueue = pParse->nTab++;
+  if( p->op==TK_UNION ){
+    eDest = pOrderBy ? SRT_DistQueue : SRT_DistFifo;
+    iDistinct = pParse->nTab++;
+  }else{
+    eDest = pOrderBy ? SRT_Queue : SRT_Fifo;
+  }
+  sqlite3SelectDestInit(&destQueue, eDest, iQueue);
+
+  /* Allocate cursors for Current, Queue, and Distinct. */
+  regCurrent = ++pParse->nMem;
+  sqlite3VdbeAddOp3(v, OP_OpenPseudo, iCurrent, regCurrent, nCol);
+  if( pOrderBy ){
+    KeyInfo *pKeyInfo = multiSelectOrderByKeyInfo(pParse, p, 1);
+    sqlite3VdbeAddOp4(v, OP_OpenEphemeral, iQueue, pOrderBy->nExpr+2, 0,
+                      (char*)pKeyInfo, P4_KEYINFO);
+    destQueue.pOrderBy = pOrderBy;
+  }else{
+    sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iQueue, nCol);
+  }
+  VdbeComment((v, "Queue table"));
+  if( iDistinct ){
+    p->addrOpenEphm[0] = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iDistinct, 0);
+    p->selFlags |= SF_UsesEphemeral;
+  }
+
+  /* Detach the ORDER BY clause from the compound SELECT */
+  p->pOrderBy = 0;
+
+  /* Store the results of the setup-query in Queue. */
+  pSetup->pNext = 0;
+  rc = sqlite3Select(pParse, pSetup, &destQueue);
+  pSetup->pNext = p;
+  if( rc ) goto end_of_recursive_query;
+
+  /* Find the next row in the Queue and output that row */
+  addrTop = sqlite3VdbeAddOp2(v, OP_Rewind, iQueue, addrBreak); VdbeCoverage(v);
+
+  /* Transfer the next row in Queue over to Current */
+  sqlite3VdbeAddOp1(v, OP_NullRow, iCurrent); /* To reset column cache */
+  if( pOrderBy ){
+    sqlite3VdbeAddOp3(v, OP_Column, iQueue, pOrderBy->nExpr+1, regCurrent);
+  }else{
+    sqlite3VdbeAddOp2(v, OP_RowData, iQueue, regCurrent);
+  }
+  sqlite3VdbeAddOp1(v, OP_Delete, iQueue);
+
+  /* Output the single row in Current */
+  addrCont = sqlite3VdbeMakeLabel(v);
+  codeOffset(v, regOffset, addrCont);
+  selectInnerLoop(pParse, p, p->pEList, iCurrent,
+      0, 0, pDest, addrCont, addrBreak);
+  if( regLimit ){
+    sqlite3VdbeAddOp2(v, OP_DecrJumpZero, regLimit, addrBreak);
+    VdbeCoverage(v);
+  }
+  sqlite3VdbeResolveLabel(v, addrCont);
+
+  /* Execute the recursive SELECT taking the single row in Current as
+  ** the value for the recursive-table. Store the results in the Queue.
+  */
+  if( p->selFlags & SF_Aggregate ){
+    sqlite3ErrorMsg(pParse, "recursive aggregate queries not supported");
+  }else{
+    p->pPrior = 0;
+    sqlite3Select(pParse, p, &destQueue);
+    assert( p->pPrior==0 );
+    p->pPrior = pSetup;
+  }
+
+  /* Keep running the loop until the Queue is empty */
+  sqlite3VdbeGoto(v, addrTop);
+  sqlite3VdbeResolveLabel(v, addrBreak);
+
+end_of_recursive_query:
+  sqlite3ExprListDelete(pParse->db, p->pOrderBy);
+  p->pOrderBy = pOrderBy;
+  p->pLimit = pLimit;
+  p->pOffset = pOffset;
+  return;
+}
+#endif /* SQLITE_OMIT_CTE */
+
+/* Forward references */
+static int multiSelectOrderBy(
+  Parse *pParse,        /* Parsing context */
+  Select *p,            /* The right-most of SELECTs to be coded */
+  SelectDest *pDest     /* What to do with query results */
+);
+
+/*
+** Handle the special case of a compound-select that originates from a
+** VALUES clause.  By handling this as a special case, we avoid deep
+** recursion, and thus do not need to enforce the SQLITE_LIMIT_COMPOUND_SELECT
+** on a VALUES clause.
+**
+** Because the Select object originates from a VALUES clause:
+**   (1) It has no LIMIT or OFFSET
+**   (2) All terms are UNION ALL
+**   (3) There is no ORDER BY clause
+*/
+static int multiSelectValues(
+  Parse *pParse,        /* Parsing context */
+  Select *p,            /* The right-most of SELECTs to be coded */
+  SelectDest *pDest     /* What to do with query results */
+){
+  Select *pPrior;
+  int nRow = 1;
+  int rc = 0;
+  assert( p->selFlags & SF_MultiValue );
+  do{
+    assert( p->selFlags & SF_Values );
+    assert( p->op==TK_ALL || (p->op==TK_SELECT && p->pPrior==0) );
+    assert( p->pLimit==0 );
+    assert( p->pOffset==0 );
+    assert( p->pNext==0 || p->pEList->nExpr==p->pNext->pEList->nExpr );
+    if( p->pPrior==0 ) break;
+    assert( p->pPrior->pNext==p );
+    p = p->pPrior;
+    nRow++;
+  }while(1);
+  while( p ){
+    pPrior = p->pPrior;
+    p->pPrior = 0;
+    rc = sqlite3Select(pParse, p, pDest);
+    p->pPrior = pPrior;
+    if( rc ) break;
+    p->nSelectRow = nRow;
+    p = p->pNext;
+  }
+  return rc;
+}
+
+/*
+** This routine is called to process a compound query form from
+** two or more separate queries using UNION, UNION ALL, EXCEPT, or
+** INTERSECT
+**
+** "p" points to the right-most of the two queries.  the query on the
+** left is p->pPrior.  The left query could also be a compound query
+** in which case this routine will be called recursively. 
+**
+** The results of the total query are to be written into a destination
+** of type eDest with parameter iParm.
+**
+** Example 1:  Consider a three-way compound SQL statement.
+**
+**     SELECT a FROM t1 UNION SELECT b FROM t2 UNION SELECT c FROM t3
+**
+** This statement is parsed up as follows:
+**
+**     SELECT c FROM t3
+**      |
+**      `----->  SELECT b FROM t2
+**                |
+**                `------>  SELECT a FROM t1
+**
+** The arrows in the diagram above represent the Select.pPrior pointer.
+** So if this routine is called with p equal to the t3 query, then
+** pPrior will be the t2 query.  p->op will be TK_UNION in this case.
+**
+** Notice that because of the way SQLite parses compound SELECTs, the
+** individual selects always group from left to right.
+*/
+static int multiSelect(
+  Parse *pParse,        /* Parsing context */
+  Select *p,            /* The right-most of SELECTs to be coded */
+  SelectDest *pDest     /* What to do with query results */
+){
+  int rc = SQLITE_OK;   /* Success code from a subroutine */
+  Select *pPrior;       /* Another SELECT immediately to our left */
+  Vdbe *v;              /* Generate code to this VDBE */
+  SelectDest dest;      /* Alternative data destination */
+  Select *pDelete = 0;  /* Chain of simple selects to delete */
+  sqlite3 *db;          /* Database connection */
+#ifndef SQLITE_OMIT_EXPLAIN
+  int iSub1 = 0;        /* EQP id of left-hand query */
+  int iSub2 = 0;        /* EQP id of right-hand query */
+#endif
+
+  /* Make sure there is no ORDER BY or LIMIT clause on prior SELECTs.  Only
+  ** the last (right-most) SELECT in the series may have an ORDER BY or LIMIT.
+  */
+  assert( p && p->pPrior );  /* Calling function guarantees this much */
+  assert( (p->selFlags & SF_Recursive)==0 || p->op==TK_ALL || p->op==TK_UNION );
+  db = pParse->db;
+  pPrior = p->pPrior;
+  dest = *pDest;
+  if( pPrior->pOrderBy ){
+    sqlite3ErrorMsg(pParse,"ORDER BY clause should come after %s not before",
+      selectOpName(p->op));
+    rc = 1;
+    goto multi_select_end;
+  }
+  if( pPrior->pLimit ){
+    sqlite3ErrorMsg(pParse,"LIMIT clause should come after %s not before",
+      selectOpName(p->op));
+    rc = 1;
+    goto multi_select_end;
+  }
+
+  v = sqlite3GetVdbe(pParse);
+  assert( v!=0 );  /* The VDBE already created by calling function */
+
+  /* Create the destination temporary table if necessary
+  */
+  if( dest.eDest==SRT_EphemTab ){
+    assert( p->pEList );
+    sqlite3VdbeAddOp2(v, OP_OpenEphemeral, dest.iSDParm, p->pEList->nExpr);
+    dest.eDest = SRT_Table;
+  }
+
+  /* Special handling for a compound-select that originates as a VALUES clause.
+  */
+  if( p->selFlags & SF_MultiValue ){
+    rc = multiSelectValues(pParse, p, &dest);
+    goto multi_select_end;
+  }
+
+  /* Make sure all SELECTs in the statement have the same number of elements
+  ** in their result sets.
+  */
+  assert( p->pEList && pPrior->pEList );
+  assert( p->pEList->nExpr==pPrior->pEList->nExpr );
+
+#ifndef SQLITE_OMIT_CTE
+  if( p->selFlags & SF_Recursive ){
+    generateWithRecursiveQuery(pParse, p, &dest);
+  }else
+#endif
+
+  /* Compound SELECTs that have an ORDER BY clause are handled separately.
+  */
+  if( p->pOrderBy ){
+    return multiSelectOrderBy(pParse, p, pDest);
+  }else
+
+  /* Generate code for the left and right SELECT statements.
+  */
+  switch( p->op ){
+    case TK_ALL: {
+      int addr = 0;
+      int nLimit;
+      assert( !pPrior->pLimit );
+      pPrior->iLimit = p->iLimit;
+      pPrior->iOffset = p->iOffset;
+      pPrior->pLimit = p->pLimit;
+      pPrior->pOffset = p->pOffset;
+      explainSetInteger(iSub1, pParse->iNextSelectId);
+      rc = sqlite3Select(pParse, pPrior, &dest);
+      p->pLimit = 0;
+      p->pOffset = 0;
+      if( rc ){
+        goto multi_select_end;
+      }
+      p->pPrior = 0;
+      p->iLimit = pPrior->iLimit;
+      p->iOffset = pPrior->iOffset;
+      if( p->iLimit ){
+        addr = sqlite3VdbeAddOp1(v, OP_IfNot, p->iLimit); VdbeCoverage(v);
+        VdbeComment((v, "Jump ahead if LIMIT reached"));
+        if( p->iOffset ){
+          sqlite3VdbeAddOp3(v, OP_OffsetLimit,
+                            p->iLimit, p->iOffset+1, p->iOffset);
+        }
+      }
+      explainSetInteger(iSub2, pParse->iNextSelectId);
+      rc = sqlite3Select(pParse, p, &dest);
+      testcase( rc!=SQLITE_OK );
+      pDelete = p->pPrior;
+      p->pPrior = pPrior;
+      p->nSelectRow = sqlite3LogEstAdd(p->nSelectRow, pPrior->nSelectRow);
+      if( pPrior->pLimit
+       && sqlite3ExprIsInteger(pPrior->pLimit, &nLimit)
+       && nLimit>0 && p->nSelectRow > sqlite3LogEst((u64)nLimit) 
+      ){
+        p->nSelectRow = sqlite3LogEst((u64)nLimit);
+      }
+      if( addr ){
+        sqlite3VdbeJumpHere(v, addr);
+      }
+      break;
+    }
+    case TK_EXCEPT:
+    case TK_UNION: {
+      int unionTab;    /* Cursor number of the temporary table holding result */
+      u8 op = 0;       /* One of the SRT_ operations to apply to self */
+      int priorOp;     /* The SRT_ operation to apply to prior selects */
+      Expr *pLimit, *pOffset; /* Saved values of p->nLimit and p->nOffset */
+      int addr;
+      SelectDest uniondest;
+
+      testcase( p->op==TK_EXCEPT );
+      testcase( p->op==TK_UNION );
+      priorOp = SRT_Union;
+      if( dest.eDest==priorOp ){
+        /* We can reuse a temporary table generated by a SELECT to our
+        ** right.
+        */
+        assert( p->pLimit==0 );      /* Not allowed on leftward elements */
+        assert( p->pOffset==0 );     /* Not allowed on leftward elements */
+        unionTab = dest.iSDParm;
+      }else{
+        /* We will need to create our own temporary table to hold the
+        ** intermediate results.
+        */
+        unionTab = pParse->nTab++;
+        assert( p->pOrderBy==0 );
+        addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, unionTab, 0);
+        assert( p->addrOpenEphm[0] == -1 );
+        p->addrOpenEphm[0] = addr;
+        findRightmost(p)->selFlags |= SF_UsesEphemeral;
+        assert( p->pEList );
+      }
+
+      /* Code the SELECT statements to our left
+      */
+      assert( !pPrior->pOrderBy );
+      sqlite3SelectDestInit(&uniondest, priorOp, unionTab);
+      explainSetInteger(iSub1, pParse->iNextSelectId);
+      rc = sqlite3Select(pParse, pPrior, &uniondest);
+      if( rc ){
+        goto multi_select_end;
+      }
+
+      /* Code the current SELECT statement
+      */
+      if( p->op==TK_EXCEPT ){
+        op = SRT_Except;
+      }else{
+        assert( p->op==TK_UNION );
+        op = SRT_Union;
+      }
+      p->pPrior = 0;
+      pLimit = p->pLimit;
+      p->pLimit = 0;
+      pOffset = p->pOffset;
+      p->pOffset = 0;
+      uniondest.eDest = op;
+      explainSetInteger(iSub2, pParse->iNextSelectId);
+      rc = sqlite3Select(pParse, p, &uniondest);
+      testcase( rc!=SQLITE_OK );
+      /* Query flattening in sqlite3Select() might refill p->pOrderBy.
+      ** Be sure to delete p->pOrderBy, therefore, to avoid a memory leak. */
+      sqlite3ExprListDelete(db, p->pOrderBy);
+      pDelete = p->pPrior;
+      p->pPrior = pPrior;
+      p->pOrderBy = 0;
+      if( p->op==TK_UNION ){
+        p->nSelectRow = sqlite3LogEstAdd(p->nSelectRow, pPrior->nSelectRow);
+      }
+      sqlite3ExprDelete(db, p->pLimit);
+      p->pLimit = pLimit;
+      p->pOffset = pOffset;
+      p->iLimit = 0;
+      p->iOffset = 0;
+
+      /* Convert the data in the temporary table into whatever form
+      ** it is that we currently need.
+      */
+      assert( unionTab==dest.iSDParm || dest.eDest!=priorOp );
+      if( dest.eDest!=priorOp ){
+        int iCont, iBreak, iStart;
+        assert( p->pEList );
+        if( dest.eDest==SRT_Output ){
+          Select *pFirst = p;
+          while( pFirst->pPrior ) pFirst = pFirst->pPrior;
+          generateColumnNames(pParse, pFirst->pSrc, pFirst->pEList);
+        }
+        iBreak = sqlite3VdbeMakeLabel(v);
+        iCont = sqlite3VdbeMakeLabel(v);
+        computeLimitRegisters(pParse, p, iBreak);
+        sqlite3VdbeAddOp2(v, OP_Rewind, unionTab, iBreak); VdbeCoverage(v);
+        iStart = sqlite3VdbeCurrentAddr(v);
+        selectInnerLoop(pParse, p, p->pEList, unionTab,
+                        0, 0, &dest, iCont, iBreak);
+        sqlite3VdbeResolveLabel(v, iCont);
+        sqlite3VdbeAddOp2(v, OP_Next, unionTab, iStart); VdbeCoverage(v);
+        sqlite3VdbeResolveLabel(v, iBreak);
+        sqlite3VdbeAddOp2(v, OP_Close, unionTab, 0);
+      }
+      break;
+    }
+    default: assert( p->op==TK_INTERSECT ); {
+      int tab1, tab2;
+      int iCont, iBreak, iStart;
+      Expr *pLimit, *pOffset;
+      int addr;
+      SelectDest intersectdest;
+      int r1;
+
+      /* INTERSECT is different from the others since it requires
+      ** two temporary tables.  Hence it has its own case.  Begin
+      ** by allocating the tables we will need.
+      */
+      tab1 = pParse->nTab++;
+      tab2 = pParse->nTab++;
+      assert( p->pOrderBy==0 );
+
+      addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab1, 0);
+      assert( p->addrOpenEphm[0] == -1 );
+      p->addrOpenEphm[0] = addr;
+      findRightmost(p)->selFlags |= SF_UsesEphemeral;
+      assert( p->pEList );
+
+      /* Code the SELECTs to our left into temporary table "tab1".
+      */
+      sqlite3SelectDestInit(&intersectdest, SRT_Union, tab1);
+      explainSetInteger(iSub1, pParse->iNextSelectId);
+      rc = sqlite3Select(pParse, pPrior, &intersectdest);
+      if( rc ){
+        goto multi_select_end;
+      }
+
+      /* Code the current SELECT into temporary table "tab2"
+      */
+      addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab2, 0);
+      assert( p->addrOpenEphm[1] == -1 );
+      p->addrOpenEphm[1] = addr;
+      p->pPrior = 0;
+      pLimit = p->pLimit;
+      p->pLimit = 0;
+      pOffset = p->pOffset;
+      p->pOffset = 0;
+      intersectdest.iSDParm = tab2;
+      explainSetInteger(iSub2, pParse->iNextSelectId);
+      rc = sqlite3Select(pParse, p, &intersectdest);
+      testcase( rc!=SQLITE_OK );
+      pDelete = p->pPrior;
+      p->pPrior = pPrior;
+      if( p->nSelectRow>pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow;
+      sqlite3ExprDelete(db, p->pLimit);
+      p->pLimit = pLimit;
+      p->pOffset = pOffset;
+
+      /* Generate code to take the intersection of the two temporary
+      ** tables.
+      */
+      assert( p->pEList );
+      if( dest.eDest==SRT_Output ){
+        Select *pFirst = p;
+        while( pFirst->pPrior ) pFirst = pFirst->pPrior;
+        generateColumnNames(pParse, pFirst->pSrc, pFirst->pEList);
+      }
+      iBreak = sqlite3VdbeMakeLabel(v);
+      iCont = sqlite3VdbeMakeLabel(v);
+      computeLimitRegisters(pParse, p, iBreak);
+      sqlite3VdbeAddOp2(v, OP_Rewind, tab1, iBreak); VdbeCoverage(v);
+      r1 = sqlite3GetTempReg(pParse);
+      iStart = sqlite3VdbeAddOp2(v, OP_RowKey, tab1, r1);
+      sqlite3VdbeAddOp4Int(v, OP_NotFound, tab2, iCont, r1, 0); VdbeCoverage(v);
+      sqlite3ReleaseTempReg(pParse, r1);
+      selectInnerLoop(pParse, p, p->pEList, tab1,
+                      0, 0, &dest, iCont, iBreak);
+      sqlite3VdbeResolveLabel(v, iCont);
+      sqlite3VdbeAddOp2(v, OP_Next, tab1, iStart); VdbeCoverage(v);
+      sqlite3VdbeResolveLabel(v, iBreak);
+      sqlite3VdbeAddOp2(v, OP_Close, tab2, 0);
+      sqlite3VdbeAddOp2(v, OP_Close, tab1, 0);
+      break;
+    }
+  }
+
+  explainComposite(pParse, p->op, iSub1, iSub2, p->op!=TK_ALL);
+
+  /* Compute collating sequences used by 
+  ** temporary tables needed to implement the compound select.
+  ** Attach the KeyInfo structure to all temporary tables.
+  **
+  ** This section is run by the right-most SELECT statement only.
+  ** SELECT statements to the left always skip this part.  The right-most
+  ** SELECT might also skip this part if it has no ORDER BY clause and
+  ** no temp tables are required.
+  */
+  if( p->selFlags & SF_UsesEphemeral ){
+    int i;                        /* Loop counter */
+    KeyInfo *pKeyInfo;            /* Collating sequence for the result set */
+    Select *pLoop;                /* For looping through SELECT statements */
+    CollSeq **apColl;             /* For looping through pKeyInfo->aColl[] */
+    int nCol;                     /* Number of columns in result set */
+
+    assert( p->pNext==0 );
+    nCol = p->pEList->nExpr;
+    pKeyInfo = sqlite3KeyInfoAlloc(db, nCol, 1);
+    if( !pKeyInfo ){
+      rc = SQLITE_NOMEM_BKPT;
+      goto multi_select_end;
+    }
+    for(i=0, apColl=pKeyInfo->aColl; i<nCol; i++, apColl++){
+      *apColl = multiSelectCollSeq(pParse, p, i);
+      if( 0==*apColl ){
+        *apColl = db->pDfltColl;
+      }
+    }
+
+    for(pLoop=p; pLoop; pLoop=pLoop->pPrior){
+      for(i=0; i<2; i++){
+        int addr = pLoop->addrOpenEphm[i];
+        if( addr<0 ){
+          /* If [0] is unused then [1] is also unused.  So we can
+          ** always safely abort as soon as the first unused slot is found */
+          assert( pLoop->addrOpenEphm[1]<0 );
+          break;
+        }
+        sqlite3VdbeChangeP2(v, addr, nCol);
+        sqlite3VdbeChangeP4(v, addr, (char*)sqlite3KeyInfoRef(pKeyInfo),
+                            P4_KEYINFO);
+        pLoop->addrOpenEphm[i] = -1;
+      }
+    }
+    sqlite3KeyInfoUnref(pKeyInfo);
+  }
+
+multi_select_end:
+  pDest->iSdst = dest.iSdst;
+  pDest->nSdst = dest.nSdst;
+  sqlite3SelectDelete(db, pDelete);
+  return rc;
+}
+#endif /* SQLITE_OMIT_COMPOUND_SELECT */
+
+/*
+** Error message for when two or more terms of a compound select have different
+** size result sets.
+*/
+SQLITE_PRIVATE void sqlite3SelectWrongNumTermsError(Parse *pParse, Select *p){
+  if( p->selFlags & SF_Values ){
+    sqlite3ErrorMsg(pParse, "all VALUES must have the same number of terms");
+  }else{
+    sqlite3ErrorMsg(pParse, "SELECTs to the left and right of %s"
+      " do not have the same number of result columns", selectOpName(p->op));
+  }
+}
+
+/*
+** Code an output subroutine for a coroutine implementation of a
+** SELECT statment.
+**
+** The data to be output is contained in pIn->iSdst.  There are
+** pIn->nSdst columns to be output.  pDest is where the output should
+** be sent.
+**
+** regReturn is the number of the register holding the subroutine
+** return address.
+**
+** If regPrev>0 then it is the first register in a vector that
+** records the previous output.  mem[regPrev] is a flag that is false
+** if there has been no previous output.  If regPrev>0 then code is
+** generated to suppress duplicates.  pKeyInfo is used for comparing
+** keys.
+**
+** If the LIMIT found in p->iLimit is reached, jump immediately to
+** iBreak.
+*/
+static int generateOutputSubroutine(
+  Parse *pParse,          /* Parsing context */
+  Select *p,              /* The SELECT statement */
+  SelectDest *pIn,        /* Coroutine supplying data */
+  SelectDest *pDest,      /* Where to send the data */
+  int regReturn,          /* The return address register */
+  int regPrev,            /* Previous result register.  No uniqueness if 0 */
+  KeyInfo *pKeyInfo,      /* For comparing with previous entry */
+  int iBreak              /* Jump here if we hit the LIMIT */
+){
+  Vdbe *v = pParse->pVdbe;
+  int iContinue;
+  int addr;
+
+  addr = sqlite3VdbeCurrentAddr(v);
+  iContinue = sqlite3VdbeMakeLabel(v);
+
+  /* Suppress duplicates for UNION, EXCEPT, and INTERSECT 
+  */
+  if( regPrev ){
+    int addr1, addr2;
+    addr1 = sqlite3VdbeAddOp1(v, OP_IfNot, regPrev); VdbeCoverage(v);
+    addr2 = sqlite3VdbeAddOp4(v, OP_Compare, pIn->iSdst, regPrev+1, pIn->nSdst,
+                              (char*)sqlite3KeyInfoRef(pKeyInfo), P4_KEYINFO);
+    sqlite3VdbeAddOp3(v, OP_Jump, addr2+2, iContinue, addr2+2); VdbeCoverage(v);
+    sqlite3VdbeJumpHere(v, addr1);
+    sqlite3VdbeAddOp3(v, OP_Copy, pIn->iSdst, regPrev+1, pIn->nSdst-1);
+    sqlite3VdbeAddOp2(v, OP_Integer, 1, regPrev);
+  }
+  if( pParse->db->mallocFailed ) return 0;
+
+  /* Suppress the first OFFSET entries if there is an OFFSET clause
+  */
+  codeOffset(v, p->iOffset, iContinue);
+
+  assert( pDest->eDest!=SRT_Exists );
+  assert( pDest->eDest!=SRT_Table );
+  switch( pDest->eDest ){
+    /* Store the result as data using a unique key.
+    */
+    case SRT_EphemTab: {
+      int r1 = sqlite3GetTempReg(pParse);
+      int r2 = sqlite3GetTempReg(pParse);
+      sqlite3VdbeAddOp3(v, OP_MakeRecord, pIn->iSdst, pIn->nSdst, r1);
+      sqlite3VdbeAddOp2(v, OP_NewRowid, pDest->iSDParm, r2);
+      sqlite3VdbeAddOp3(v, OP_Insert, pDest->iSDParm, r1, r2);
+      sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
+      sqlite3ReleaseTempReg(pParse, r2);
+      sqlite3ReleaseTempReg(pParse, r1);
+      break;
+    }
+
+#ifndef SQLITE_OMIT_SUBQUERY
+    /* If we are creating a set for an "expr IN (SELECT ...)".
+    */
+    case SRT_Set: {
+      int r1;
+      testcase( pIn->nSdst>1 );
+      r1 = sqlite3GetTempReg(pParse);
+      sqlite3VdbeAddOp4(v, OP_MakeRecord, pIn->iSdst, pIn->nSdst, 
+          r1, pDest->zAffSdst, pIn->nSdst);
+      sqlite3ExprCacheAffinityChange(pParse, pIn->iSdst, pIn->nSdst);
+      sqlite3VdbeAddOp2(v, OP_IdxInsert, pDest->iSDParm, r1);
+      sqlite3ReleaseTempReg(pParse, r1);
+      break;
+    }
+
+    /* If this is a scalar select that is part of an expression, then
+    ** store the results in the appropriate memory cell and break out
+    ** of the scan loop.
+    */
+    case SRT_Mem: {
+      assert( pIn->nSdst==1 || pParse->nErr>0 );  testcase( pIn->nSdst!=1 );
+      sqlite3ExprCodeMove(pParse, pIn->iSdst, pDest->iSDParm, 1);
+      /* The LIMIT clause will jump out of the loop for us */
+      break;
+    }
+#endif /* #ifndef SQLITE_OMIT_SUBQUERY */
+
+    /* The results are stored in a sequence of registers
+    ** starting at pDest->iSdst.  Then the co-routine yields.
+    */
+    case SRT_Coroutine: {
+      if( pDest->iSdst==0 ){
+        pDest->iSdst = sqlite3GetTempRange(pParse, pIn->nSdst);
+        pDest->nSdst = pIn->nSdst;
+      }
+      sqlite3ExprCodeMove(pParse, pIn->iSdst, pDest->iSdst, pIn->nSdst);
+      sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm);
+      break;
+    }
+
+    /* If none of the above, then the result destination must be
+    ** SRT_Output.  This routine is never called with any other
+    ** destination other than the ones handled above or SRT_Output.
+    **
+    ** For SRT_Output, results are stored in a sequence of registers.  
+    ** Then the OP_ResultRow opcode is used to cause sqlite3_step() to
+    ** return the next row of result.
+    */
+    default: {
+      assert( pDest->eDest==SRT_Output );
+      sqlite3VdbeAddOp2(v, OP_ResultRow, pIn->iSdst, pIn->nSdst);
+      sqlite3ExprCacheAffinityChange(pParse, pIn->iSdst, pIn->nSdst);
+      break;
+    }
+  }
+
+  /* Jump to the end of the loop if the LIMIT is reached.
+  */
+  if( p->iLimit ){
+    sqlite3VdbeAddOp2(v, OP_DecrJumpZero, p->iLimit, iBreak); VdbeCoverage(v);
+  }
+
+  /* Generate the subroutine return
+  */
+  sqlite3VdbeResolveLabel(v, iContinue);
+  sqlite3VdbeAddOp1(v, OP_Return, regReturn);
+
+  return addr;
+}
+
+/*
+** Alternative compound select code generator for cases when there
+** is an ORDER BY clause.
+**
+** We assume a query of the following form:
+**
+**      <selectA>  <operator>  <selectB>  ORDER BY <orderbylist>
+**
+** <operator> is one of UNION ALL, UNION, EXCEPT, or INTERSECT.  The idea
+** is to code both <selectA> and <selectB> with the ORDER BY clause as
+** co-routines.  Then run the co-routines in parallel and merge the results
+** into the output.  In addition to the two coroutines (called selectA and
+** selectB) there are 7 subroutines:
+**
+**    outA:    Move the output of the selectA coroutine into the output
+**             of the compound query.
+**
+**    outB:    Move the output of the selectB coroutine into the output
+**             of the compound query.  (Only generated for UNION and
+**             UNION ALL.  EXCEPT and INSERTSECT never output a row that
+**             appears only in B.)
+**
+**    AltB:    Called when there is data from both coroutines and A<B.
+**
+**    AeqB:    Called when there is data from both coroutines and A==B.
+**
+**    AgtB:    Called when there is data from both coroutines and A>B.
+**
+**    EofA:    Called when data is exhausted from selectA.
+**
+**    EofB:    Called when data is exhausted from selectB.
+**
+** The implementation of the latter five subroutines depend on which 
+** <operator> is used:
+**
+**
+**             UNION ALL         UNION            EXCEPT          INTERSECT
+**          -------------  -----------------  --------------  -----------------
+**   AltB:   outA, nextA      outA, nextA       outA, nextA         nextA
+**
+**   AeqB:   outA, nextA         nextA             nextA         outA, nextA
+**
+**   AgtB:   outB, nextB      outB, nextB          nextB            nextB
+**
+**   EofA:   outB, nextB      outB, nextB          halt             halt
+**
+**   EofB:   outA, nextA      outA, nextA       outA, nextA         halt
+**
+** In the AltB, AeqB, and AgtB subroutines, an EOF on A following nextA
+** causes an immediate jump to EofA and an EOF on B following nextB causes
+** an immediate jump to EofB.  Within EofA and EofB, and EOF on entry or
+** following nextX causes a jump to the end of the select processing.
+**
+** Duplicate removal in the UNION, EXCEPT, and INTERSECT cases is handled
+** within the output subroutine.  The regPrev register set holds the previously
+** output value.  A comparison is made against this value and the output
+** is skipped if the next results would be the same as the previous.
+**
+** The implementation plan is to implement the two coroutines and seven
+** subroutines first, then put the control logic at the bottom.  Like this:
+**
+**          goto Init
+**     coA: coroutine for left query (A)
+**     coB: coroutine for right query (B)
+**    outA: output one row of A
+**    outB: output one row of B (UNION and UNION ALL only)
+**    EofA: ...
+**    EofB: ...
+**    AltB: ...
+**    AeqB: ...
+**    AgtB: ...
+**    Init: initialize coroutine registers
+**          yield coA
+**          if eof(A) goto EofA
+**          yield coB
+**          if eof(B) goto EofB
+**    Cmpr: Compare A, B
+**          Jump AltB, AeqB, AgtB
+**     End: ...
+**
+** We call AltB, AeqB, AgtB, EofA, and EofB "subroutines" but they are not
+** actually called using Gosub and they do not Return.  EofA and EofB loop
+** until all data is exhausted then jump to the "end" labe.  AltB, AeqB,
+** and AgtB jump to either L2 or to one of EofA or EofB.
+*/
+#ifndef SQLITE_OMIT_COMPOUND_SELECT
+static int multiSelectOrderBy(
+  Parse *pParse,        /* Parsing context */
+  Select *p,            /* The right-most of SELECTs to be coded */
+  SelectDest *pDest     /* What to do with query results */
+){
+  int i, j;             /* Loop counters */
+  Select *pPrior;       /* Another SELECT immediately to our left */
+  Vdbe *v;              /* Generate code to this VDBE */
+  SelectDest destA;     /* Destination for coroutine A */
+  SelectDest destB;     /* Destination for coroutine B */
+  int regAddrA;         /* Address register for select-A coroutine */
+  int regAddrB;         /* Address register for select-B coroutine */
+  int addrSelectA;      /* Address of the select-A coroutine */
+  int addrSelectB;      /* Address of the select-B coroutine */
+  int regOutA;          /* Address register for the output-A subroutine */
+  int regOutB;          /* Address register for the output-B subroutine */
+  int addrOutA;         /* Address of the output-A subroutine */
+  int addrOutB = 0;     /* Address of the output-B subroutine */
+  int addrEofA;         /* Address of the select-A-exhausted subroutine */
+  int addrEofA_noB;     /* Alternate addrEofA if B is uninitialized */
+  int addrEofB;         /* Address of the select-B-exhausted subroutine */
+  int addrAltB;         /* Address of the A<B subroutine */
+  int addrAeqB;         /* Address of the A==B subroutine */
+  int addrAgtB;         /* Address of the A>B subroutine */
+  int regLimitA;        /* Limit register for select-A */
+  int regLimitB;        /* Limit register for select-A */
+  int regPrev;          /* A range of registers to hold previous output */
+  int savedLimit;       /* Saved value of p->iLimit */
+  int savedOffset;      /* Saved value of p->iOffset */
+  int labelCmpr;        /* Label for the start of the merge algorithm */
+  int labelEnd;         /* Label for the end of the overall SELECT stmt */
+  int addr1;            /* Jump instructions that get retargetted */
+  int op;               /* One of TK_ALL, TK_UNION, TK_EXCEPT, TK_INTERSECT */
+  KeyInfo *pKeyDup = 0; /* Comparison information for duplicate removal */
+  KeyInfo *pKeyMerge;   /* Comparison information for merging rows */
+  sqlite3 *db;          /* Database connection */
+  ExprList *pOrderBy;   /* The ORDER BY clause */
+  int nOrderBy;         /* Number of terms in the ORDER BY clause */
+  int *aPermute;        /* Mapping from ORDER BY terms to result set columns */
+#ifndef SQLITE_OMIT_EXPLAIN
+  int iSub1;            /* EQP id of left-hand query */
+  int iSub2;            /* EQP id of right-hand query */
+#endif
+
+  assert( p->pOrderBy!=0 );
+  assert( pKeyDup==0 ); /* "Managed" code needs this.  Ticket #3382. */
+  db = pParse->db;
+  v = pParse->pVdbe;
+  assert( v!=0 );       /* Already thrown the error if VDBE alloc failed */
+  labelEnd = sqlite3VdbeMakeLabel(v);
+  labelCmpr = sqlite3VdbeMakeLabel(v);
+
+
+  /* Patch up the ORDER BY clause
+  */
+  op = p->op;  
+  pPrior = p->pPrior;
+  assert( pPrior->pOrderBy==0 );
+  pOrderBy = p->pOrderBy;
+  assert( pOrderBy );
+  nOrderBy = pOrderBy->nExpr;
+
+  /* For operators other than UNION ALL we have to make sure that
+  ** the ORDER BY clause covers every term of the result set.  Add
+  ** terms to the ORDER BY clause as necessary.
+  */
+  if( op!=TK_ALL ){
+    for(i=1; db->mallocFailed==0 && i<=p->pEList->nExpr; i++){
+      struct ExprList_item *pItem;
+      for(j=0, pItem=pOrderBy->a; j<nOrderBy; j++, pItem++){
+        assert( pItem->u.x.iOrderByCol>0 );
+        if( pItem->u.x.iOrderByCol==i ) break;
+      }
+      if( j==nOrderBy ){
+        Expr *pNew = sqlite3Expr(db, TK_INTEGER, 0);
+        if( pNew==0 ) return SQLITE_NOMEM_BKPT;
+        pNew->flags |= EP_IntValue;
+        pNew->u.iValue = i;
+        pOrderBy = sqlite3ExprListAppend(pParse, pOrderBy, pNew);
+        if( pOrderBy ) pOrderBy->a[nOrderBy++].u.x.iOrderByCol = (u16)i;
+      }
+    }
+  }
+
+  /* Compute the comparison permutation and keyinfo that is used with
+  ** the permutation used to determine if the next
+  ** row of results comes from selectA or selectB.  Also add explicit
+  ** collations to the ORDER BY clause terms so that when the subqueries
+  ** to the right and the left are evaluated, they use the correct
+  ** collation.
+  */
+  aPermute = sqlite3DbMallocRawNN(db, sizeof(int)*(nOrderBy + 1));
+  if( aPermute ){
+    struct ExprList_item *pItem;
+    aPermute[0] = nOrderBy;
+    for(i=1, pItem=pOrderBy->a; i<=nOrderBy; i++, pItem++){
+      assert( pItem->u.x.iOrderByCol>0 );
+      assert( pItem->u.x.iOrderByCol<=p->pEList->nExpr );
+      aPermute[i] = pItem->u.x.iOrderByCol - 1;
+    }
+    pKeyMerge = multiSelectOrderByKeyInfo(pParse, p, 1);
+  }else{
+    pKeyMerge = 0;
+  }
+
+  /* Reattach the ORDER BY clause to the query.
+  */
+  p->pOrderBy = pOrderBy;
+  pPrior->pOrderBy = sqlite3ExprListDup(pParse->db, pOrderBy, 0);
+
+  /* Allocate a range of temporary registers and the KeyInfo needed
+  ** for the logic that removes duplicate result rows when the
+  ** operator is UNION, EXCEPT, or INTERSECT (but not UNION ALL).
+  */
+  if( op==TK_ALL ){
+    regPrev = 0;
+  }else{
+    int nExpr = p->pEList->nExpr;
+    assert( nOrderBy>=nExpr || db->mallocFailed );
+    regPrev = pParse->nMem+1;
+    pParse->nMem += nExpr+1;
+    sqlite3VdbeAddOp2(v, OP_Integer, 0, regPrev);
+    pKeyDup = sqlite3KeyInfoAlloc(db, nExpr, 1);
+    if( pKeyDup ){
+      assert( sqlite3KeyInfoIsWriteable(pKeyDup) );
+      for(i=0; i<nExpr; i++){
+        pKeyDup->aColl[i] = multiSelectCollSeq(pParse, p, i);
+        pKeyDup->aSortOrder[i] = 0;
+      }
+    }
+  }
+ 
+  /* Separate the left and the right query from one another
+  */
+  p->pPrior = 0;
+  pPrior->pNext = 0;
+  sqlite3ResolveOrderGroupBy(pParse, p, p->pOrderBy, "ORDER");
+  if( pPrior->pPrior==0 ){
+    sqlite3ResolveOrderGroupBy(pParse, pPrior, pPrior->pOrderBy, "ORDER");
+  }
+
+  /* Compute the limit registers */
+  computeLimitRegisters(pParse, p, labelEnd);
+  if( p->iLimit && op==TK_ALL ){
+    regLimitA = ++pParse->nMem;
+    regLimitB = ++pParse->nMem;
+    sqlite3VdbeAddOp2(v, OP_Copy, p->iOffset ? p->iOffset+1 : p->iLimit,
+                                  regLimitA);
+    sqlite3VdbeAddOp2(v, OP_Copy, regLimitA, regLimitB);
+  }else{
+    regLimitA = regLimitB = 0;
+  }
+  sqlite3ExprDelete(db, p->pLimit);
+  p->pLimit = 0;
+  sqlite3ExprDelete(db, p->pOffset);
+  p->pOffset = 0;
+
+  regAddrA = ++pParse->nMem;
+  regAddrB = ++pParse->nMem;
+  regOutA = ++pParse->nMem;
+  regOutB = ++pParse->nMem;
+  sqlite3SelectDestInit(&destA, SRT_Coroutine, regAddrA);
+  sqlite3SelectDestInit(&destB, SRT_Coroutine, regAddrB);
+
+  /* Generate a coroutine to evaluate the SELECT statement to the
+  ** left of the compound operator - the "A" select.
+  */
+  addrSelectA = sqlite3VdbeCurrentAddr(v) + 1;
+  addr1 = sqlite3VdbeAddOp3(v, OP_InitCoroutine, regAddrA, 0, addrSelectA);
+  VdbeComment((v, "left SELECT"));
+  pPrior->iLimit = regLimitA;
+  explainSetInteger(iSub1, pParse->iNextSelectId);
+  sqlite3Select(pParse, pPrior, &destA);
+  sqlite3VdbeEndCoroutine(v, regAddrA);
+  sqlite3VdbeJumpHere(v, addr1);
+
+  /* Generate a coroutine to evaluate the SELECT statement on 
+  ** the right - the "B" select
+  */
+  addrSelectB = sqlite3VdbeCurrentAddr(v) + 1;
+  addr1 = sqlite3VdbeAddOp3(v, OP_InitCoroutine, regAddrB, 0, addrSelectB);
+  VdbeComment((v, "right SELECT"));
+  savedLimit = p->iLimit;
+  savedOffset = p->iOffset;
+  p->iLimit = regLimitB;
+  p->iOffset = 0;  
+  explainSetInteger(iSub2, pParse->iNextSelectId);
+  sqlite3Select(pParse, p, &destB);
+  p->iLimit = savedLimit;
+  p->iOffset = savedOffset;
+  sqlite3VdbeEndCoroutine(v, regAddrB);
+
+  /* Generate a subroutine that outputs the current row of the A
+  ** select as the next output row of the compound select.
+  */
+  VdbeNoopComment((v, "Output routine for A"));
+  addrOutA = generateOutputSubroutine(pParse,
+                 p, &destA, pDest, regOutA,
+                 regPrev, pKeyDup, labelEnd);
+  
+  /* Generate a subroutine that outputs the current row of the B
+  ** select as the next output row of the compound select.
+  */
+  if( op==TK_ALL || op==TK_UNION ){
+    VdbeNoopComment((v, "Output routine for B"));
+    addrOutB = generateOutputSubroutine(pParse,
+                 p, &destB, pDest, regOutB,
+                 regPrev, pKeyDup, labelEnd);
+  }
+  sqlite3KeyInfoUnref(pKeyDup);
+
+  /* Generate a subroutine to run when the results from select A
+  ** are exhausted and only data in select B remains.
+  */
+  if( op==TK_EXCEPT || op==TK_INTERSECT ){
+    addrEofA_noB = addrEofA = labelEnd;
+  }else{  
+    VdbeNoopComment((v, "eof-A subroutine"));
+    addrEofA = sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
+    addrEofA_noB = sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, labelEnd);
+                                     VdbeCoverage(v);
+    sqlite3VdbeGoto(v, addrEofA);
+    p->nSelectRow = sqlite3LogEstAdd(p->nSelectRow, pPrior->nSelectRow);
+  }
+
+  /* Generate a subroutine to run when the results from select B
+  ** are exhausted and only data in select A remains.
+  */
+  if( op==TK_INTERSECT ){
+    addrEofB = addrEofA;
+    if( p->nSelectRow > pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow;
+  }else{  
+    VdbeNoopComment((v, "eof-B subroutine"));
+    addrEofB = sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA);
+    sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, labelEnd); VdbeCoverage(v);
+    sqlite3VdbeGoto(v, addrEofB);
+  }
+
+  /* Generate code to handle the case of A<B
+  */
+  VdbeNoopComment((v, "A-lt-B subroutine"));
+  addrAltB = sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA);
+  sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, addrEofA); VdbeCoverage(v);
+  sqlite3VdbeGoto(v, labelCmpr);
+
+  /* Generate code to handle the case of A==B
+  */
+  if( op==TK_ALL ){
+    addrAeqB = addrAltB;
+  }else if( op==TK_INTERSECT ){
+    addrAeqB = addrAltB;
+    addrAltB++;
+  }else{
+    VdbeNoopComment((v, "A-eq-B subroutine"));
+    addrAeqB =
+    sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, addrEofA); VdbeCoverage(v);
+    sqlite3VdbeGoto(v, labelCmpr);
+  }
+
+  /* Generate code to handle the case of A>B
+  */
+  VdbeNoopComment((v, "A-gt-B subroutine"));
+  addrAgtB = sqlite3VdbeCurrentAddr(v);
+  if( op==TK_ALL || op==TK_UNION ){
+    sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
+  }
+  sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, addrEofB); VdbeCoverage(v);
+  sqlite3VdbeGoto(v, labelCmpr);
+
+  /* This code runs once to initialize everything.
+  */
+  sqlite3VdbeJumpHere(v, addr1);
+  sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, addrEofA_noB); VdbeCoverage(v);
+  sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, addrEofB); VdbeCoverage(v);
+
+  /* Implement the main merge loop
+  */
+  sqlite3VdbeResolveLabel(v, labelCmpr);
+  sqlite3VdbeAddOp4(v, OP_Permutation, 0, 0, 0, (char*)aPermute, P4_INTARRAY);
+  sqlite3VdbeAddOp4(v, OP_Compare, destA.iSdst, destB.iSdst, nOrderBy,
+                         (char*)pKeyMerge, P4_KEYINFO);
+  sqlite3VdbeChangeP5(v, OPFLAG_PERMUTE);
+  sqlite3VdbeAddOp3(v, OP_Jump, addrAltB, addrAeqB, addrAgtB); VdbeCoverage(v);
+
+  /* Jump to the this point in order to terminate the query.
+  */
+  sqlite3VdbeResolveLabel(v, labelEnd);
+
+  /* Set the number of output columns
+  */
+  if( pDest->eDest==SRT_Output ){
+    Select *pFirst = pPrior;
+    while( pFirst->pPrior ) pFirst = pFirst->pPrior;
+    generateColumnNames(pParse, pFirst->pSrc, pFirst->pEList);
+  }
+
+  /* Reassembly the compound query so that it will be freed correctly
+  ** by the calling function */
+  if( p->pPrior ){
+    sqlite3SelectDelete(db, p->pPrior);
+  }
+  p->pPrior = pPrior;
+  pPrior->pNext = p;
+
+  /*** TBD:  Insert subroutine calls to close cursors on incomplete
+  **** subqueries ****/
+  explainComposite(pParse, p->op, iSub1, iSub2, 0);
+  return pParse->nErr!=0;
+}
+#endif
+
+#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
+/* Forward Declarations */
+static void substExprList(sqlite3*, ExprList*, int, ExprList*);
+static void substSelect(sqlite3*, Select *, int, ExprList*, int);
+
+/*
+** Scan through the expression pExpr.  Replace every reference to
+** a column in table number iTable with a copy of the iColumn-th
+** entry in pEList.  (But leave references to the ROWID column 
+** unchanged.)
+**
+** This routine is part of the flattening procedure.  A subquery
+** whose result set is defined by pEList appears as entry in the
+** FROM clause of a SELECT such that the VDBE cursor assigned to that
+** FORM clause entry is iTable.  This routine make the necessary 
+** changes to pExpr so that it refers directly to the source table
+** of the subquery rather the result set of the subquery.
+*/
+static Expr *substExpr(
+  sqlite3 *db,        /* Report malloc errors to this connection */
+  Expr *pExpr,        /* Expr in which substitution occurs */
+  int iTable,         /* Table to be substituted */
+  ExprList *pEList    /* Substitute expressions */
+){
+  if( pExpr==0 ) return 0;
+  if( pExpr->op==TK_COLUMN && pExpr->iTable==iTable ){
+    if( pExpr->iColumn<0 ){
+      pExpr->op = TK_NULL;
+    }else{
+      Expr *pNew;
+      assert( pEList!=0 && pExpr->iColumn<pEList->nExpr );
+      assert( pExpr->pLeft==0 && pExpr->pRight==0 );
+      pNew = sqlite3ExprDup(db, pEList->a[pExpr->iColumn].pExpr, 0);
+      sqlite3ExprDelete(db, pExpr);
+      pExpr = pNew;
+    }
+  }else{
+    pExpr->pLeft = substExpr(db, pExpr->pLeft, iTable, pEList);
+    pExpr->pRight = substExpr(db, pExpr->pRight, iTable, pEList);
+    if( ExprHasProperty(pExpr, EP_xIsSelect) ){
+      substSelect(db, pExpr->x.pSelect, iTable, pEList, 1);
+    }else{
+      substExprList(db, pExpr->x.pList, iTable, pEList);
+    }
+  }
+  return pExpr;
+}
+static void substExprList(
+  sqlite3 *db,         /* Report malloc errors here */
+  ExprList *pList,     /* List to scan and in which to make substitutes */
+  int iTable,          /* Table to be substituted */
+  ExprList *pEList     /* Substitute values */
+){
+  int i;
+  if( pList==0 ) return;
+  for(i=0; i<pList->nExpr; i++){
+    pList->a[i].pExpr = substExpr(db, pList->a[i].pExpr, iTable, pEList);
+  }
+}
+static void substSelect(
+  sqlite3 *db,         /* Report malloc errors here */
+  Select *p,           /* SELECT statement in which to make substitutions */
+  int iTable,          /* Table to be replaced */
+  ExprList *pEList,    /* Substitute values */
+  int doPrior          /* Do substitutes on p->pPrior too */
+){
+  SrcList *pSrc;
+  struct SrcList_item *pItem;
+  int i;
+  if( !p ) return;
+  do{
+    substExprList(db, p->pEList, iTable, pEList);
+    substExprList(db, p->pGroupBy, iTable, pEList);
+    substExprList(db, p->pOrderBy, iTable, pEList);
+    p->pHaving = substExpr(db, p->pHaving, iTable, pEList);
+    p->pWhere = substExpr(db, p->pWhere, iTable, pEList);
+    pSrc = p->pSrc;
+    assert( pSrc!=0 );
+    for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){
+      substSelect(db, pItem->pSelect, iTable, pEList, 1);
+      if( pItem->fg.isTabFunc ){
+        substExprList(db, pItem->u1.pFuncArg, iTable, pEList);
+      }
+    }
+  }while( doPrior && (p = p->pPrior)!=0 );
+}
+#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
+
+#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
+/*
+** This routine attempts to flatten subqueries as a performance optimization.
+** This routine returns 1 if it makes changes and 0 if no flattening occurs.
+**
+** To understand the concept of flattening, consider the following
+** query:
+**
+**     SELECT a FROM (SELECT x+y AS a FROM t1 WHERE z<100) WHERE a>5
+**
+** The default way of implementing this query is to execute the
+** subquery first and store the results in a temporary table, then
+** run the outer query on that temporary table.  This requires two
+** passes over the data.  Furthermore, because the temporary table
+** has no indices, the WHERE clause on the outer query cannot be
+** optimized.
+**
+** This routine attempts to rewrite queries such as the above into
+** a single flat select, like this:
+**
+**     SELECT x+y AS a FROM t1 WHERE z<100 AND a>5
+**
+** The code generated for this simplification gives the same result
+** but only has to scan the data once.  And because indices might 
+** exist on the table t1, a complete scan of the data might be
+** avoided.
+**
+** Flattening is only attempted if all of the following are true:
+**
+**   (1)  The subquery and the outer query do not both use aggregates.
+**
+**   (2)  The subquery is not an aggregate or (2a) the outer query is not a join
+**        and (2b) the outer query does not use subqueries other than the one
+**        FROM-clause subquery that is a candidate for flattening.  (2b is
+**        due to ticket [2f7170d73bf9abf80] from 2015-02-09.)
+**
+**   (3)  The subquery is not the right operand of a left outer join
+**        (Originally ticket #306.  Strengthened by ticket #3300)
+**
+**   (4)  The subquery is not DISTINCT.
+**
+**  (**)  At one point restrictions (4) and (5) defined a subset of DISTINCT
+**        sub-queries that were excluded from this optimization. Restriction 
+**        (4) has since been expanded to exclude all DISTINCT subqueries.
+**
+**   (6)  The subquery does not use aggregates or the outer query is not
+**        DISTINCT.
+**
+**   (7)  The subquery has a FROM clause.  TODO:  For subqueries without
+**        A FROM clause, consider adding a FROM close with the special
+**        table sqlite_once that consists of a single row containing a
+**        single NULL.
+**
+**   (8)  The subquery does not use LIMIT or the outer query is not a join.
+**
+**   (9)  The subquery does not use LIMIT or the outer query does not use
+**        aggregates.
+**
+**  (**)  Restriction (10) was removed from the code on 2005-02-05 but we
+**        accidently carried the comment forward until 2014-09-15.  Original
+**        text: "The subquery does not use aggregates or the outer query 
+**        does not use LIMIT."
+**
+**  (11)  The subquery and the outer query do not both have ORDER BY clauses.
+**
+**  (**)  Not implemented.  Subsumed into restriction (3).  Was previously
+**        a separate restriction deriving from ticket #350.
+**
+**  (13)  The subquery and outer query do not both use LIMIT.
+**
+**  (14)  The subquery does not use OFFSET.
+**
+**  (15)  The outer query is not part of a compound select or the
+**        subquery does not have a LIMIT clause.
+**        (See ticket #2339 and ticket [02a8e81d44]).
+**
+**  (16)  The outer query is not an aggregate or the subquery does
+**        not contain ORDER BY.  (Ticket #2942)  This used to not matter
+**        until we introduced the group_concat() function.  
+**
+**  (17)  The sub-query is not a compound select, or it is a UNION ALL 
+**        compound clause made up entirely of non-aggregate queries, and 
+**        the parent query:
+**
+**          * is not itself part of a compound select,
+**          * is not an aggregate or DISTINCT query, and
+**          * is not a join
+**
+**        The parent and sub-query may contain WHERE clauses. Subject to
+**        rules (11), (13) and (14), they may also contain ORDER BY,
+**        LIMIT and OFFSET clauses.  The subquery cannot use any compound
+**        operator other than UNION ALL because all the other compound
+**        operators have an implied DISTINCT which is disallowed by
+**        restriction (4).
+**
+**        Also, each component of the sub-query must return the same number
+**        of result columns. This is actually a requirement for any compound
+**        SELECT statement, but all the code here does is make sure that no
+**        such (illegal) sub-query is flattened. The caller will detect the
+**        syntax error and return a detailed message.
+**
+**  (18)  If the sub-query is a compound select, then all terms of the
+**        ORDER by clause of the parent must be simple references to 
+**        columns of the sub-query.
+**
+**  (19)  The subquery does not use LIMIT or the outer query does not
+**        have a WHERE clause.
+**
+**  (20)  If the sub-query is a compound select, then it must not use
+**        an ORDER BY clause.  Ticket #3773.  We could relax this constraint
+**        somewhat by saying that the terms of the ORDER BY clause must
+**        appear as unmodified result columns in the outer query.  But we
+**        have other optimizations in mind to deal with that case.
+**
+**  (21)  The subquery does not use LIMIT or the outer query is not
+**        DISTINCT.  (See ticket [752e1646fc]).
+**
+**  (22)  The subquery is not a recursive CTE.
+**
+**  (23)  The parent is not a recursive CTE, or the sub-query is not a
+**        compound query. This restriction is because transforming the
+**        parent to a compound query confuses the code that handles
+**        recursive queries in multiSelect().
+**
+**  (24)  The subquery is not an aggregate that uses the built-in min() or 
+**        or max() functions.  (Without this restriction, a query like:
+**        "SELECT x FROM (SELECT max(y), x FROM t1)" would not necessarily
+**        return the value X for which Y was maximal.)
+**
+**
+** In this routine, the "p" parameter is a pointer to the outer query.
+** The subquery is p->pSrc->a[iFrom].  isAgg is true if the outer query
+** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates.
+**
+** If flattening is not attempted, this routine is a no-op and returns 0.
+** If flattening is attempted this routine returns 1.
+**
+** All of the expression analysis must occur on both the outer query and
+** the subquery before this routine runs.
+*/
+static int flattenSubquery(
+  Parse *pParse,       /* Parsing context */
+  Select *p,           /* The parent or outer SELECT statement */
+  int iFrom,           /* Index in p->pSrc->a[] of the inner subquery */
+  int isAgg,           /* True if outer SELECT uses aggregate functions */
+  int subqueryIsAgg    /* True if the subquery uses aggregate functions */
+){
+  const char *zSavedAuthContext = pParse->zAuthContext;
+  Select *pParent;    /* Current UNION ALL term of the other query */
+  Select *pSub;       /* The inner query or "subquery" */
+  Select *pSub1;      /* Pointer to the rightmost select in sub-query */
+  SrcList *pSrc;      /* The FROM clause of the outer query */
+  SrcList *pSubSrc;   /* The FROM clause of the subquery */
+  ExprList *pList;    /* The result set of the outer query */
+  int iParent;        /* VDBE cursor number of the pSub result set temp table */
+  int i;              /* Loop counter */
+  Expr *pWhere;                    /* The WHERE clause */
+  struct SrcList_item *pSubitem;   /* The subquery */
+  sqlite3 *db = pParse->db;
+
+  /* Check to see if flattening is permitted.  Return 0 if not.
+  */
+  assert( p!=0 );
+  assert( p->pPrior==0 );  /* Unable to flatten compound queries */
+  if( OptimizationDisabled(db, SQLITE_QueryFlattener) ) return 0;
+  pSrc = p->pSrc;
+  assert( pSrc && iFrom>=0 && iFrom<pSrc->nSrc );
+  pSubitem = &pSrc->a[iFrom];
+  iParent = pSubitem->iCursor;
+  pSub = pSubitem->pSelect;
+  assert( pSub!=0 );
+  if( subqueryIsAgg ){
+    if( isAgg ) return 0;                                /* Restriction (1)   */
+    if( pSrc->nSrc>1 ) return 0;                         /* Restriction (2a)  */
+    if( (p->pWhere && ExprHasProperty(p->pWhere,EP_Subquery))
+     || (sqlite3ExprListFlags(p->pEList) & EP_Subquery)!=0
+     || (sqlite3ExprListFlags(p->pOrderBy) & EP_Subquery)!=0
+    ){
+      return 0;                                          /* Restriction (2b)  */
+    }
+  }
+    
+  pSubSrc = pSub->pSrc;
+  assert( pSubSrc );
+  /* Prior to version 3.1.2, when LIMIT and OFFSET had to be simple constants,
+  ** not arbitrary expressions, we allowed some combining of LIMIT and OFFSET
+  ** because they could be computed at compile-time.  But when LIMIT and OFFSET
+  ** became arbitrary expressions, we were forced to add restrictions (13)
+  ** and (14). */
+  if( pSub->pLimit && p->pLimit ) return 0;              /* Restriction (13) */
+  if( pSub->pOffset ) return 0;                          /* Restriction (14) */
+  if( (p->selFlags & SF_Compound)!=0 && pSub->pLimit ){
+    return 0;                                            /* Restriction (15) */
+  }
+  if( pSubSrc->nSrc==0 ) return 0;                       /* Restriction (7)  */
+  if( pSub->selFlags & SF_Distinct ) return 0;           /* Restriction (5)  */
+  if( pSub->pLimit && (pSrc->nSrc>1 || isAgg) ){
+     return 0;         /* Restrictions (8)(9) */
+  }
+  if( (p->selFlags & SF_Distinct)!=0 && subqueryIsAgg ){
+     return 0;         /* Restriction (6)  */
+  }
+  if( p->pOrderBy && pSub->pOrderBy ){
+     return 0;                                           /* Restriction (11) */
+  }
+  if( isAgg && pSub->pOrderBy ) return 0;                /* Restriction (16) */
+  if( pSub->pLimit && p->pWhere ) return 0;              /* Restriction (19) */
+  if( pSub->pLimit && (p->selFlags & SF_Distinct)!=0 ){
+     return 0;         /* Restriction (21) */
+  }
+  testcase( pSub->selFlags & SF_Recursive );
+  testcase( pSub->selFlags & SF_MinMaxAgg );
+  if( pSub->selFlags & (SF_Recursive|SF_MinMaxAgg) ){
+    return 0; /* Restrictions (22) and (24) */
+  }
+  if( (p->selFlags & SF_Recursive) && pSub->pPrior ){
+    return 0; /* Restriction (23) */
+  }
+
+  /* OBSOLETE COMMENT 1:
+  ** Restriction 3:  If the subquery is a join, make sure the subquery is 
+  ** not used as the right operand of an outer join.  Examples of why this
+  ** is not allowed:
+  **
+  **         t1 LEFT OUTER JOIN (t2 JOIN t3)
+  **
+  ** If we flatten the above, we would get
+  **
+  **         (t1 LEFT OUTER JOIN t2) JOIN t3
+  **
+  ** which is not at all the same thing.
+  **
+  ** OBSOLETE COMMENT 2:
+  ** Restriction 12:  If the subquery is the right operand of a left outer
+  ** join, make sure the subquery has no WHERE clause.
+  ** An examples of why this is not allowed:
+  **
+  **         t1 LEFT OUTER JOIN (SELECT * FROM t2 WHERE t2.x>0)
+  **
+  ** If we flatten the above, we would get
+  **
+  **         (t1 LEFT OUTER JOIN t2) WHERE t2.x>0
+  **
+  ** But the t2.x>0 test will always fail on a NULL row of t2, which
+  ** effectively converts the OUTER JOIN into an INNER JOIN.
+  **
+  ** THIS OVERRIDES OBSOLETE COMMENTS 1 AND 2 ABOVE:
+  ** Ticket #3300 shows that flattening the right term of a LEFT JOIN
+  ** is fraught with danger.  Best to avoid the whole thing.  If the
+  ** subquery is the right term of a LEFT JOIN, then do not flatten.
+  */
+  if( (pSubitem->fg.jointype & JT_OUTER)!=0 ){
+    return 0;
+  }
+
+  /* Restriction 17: If the sub-query is a compound SELECT, then it must
+  ** use only the UNION ALL operator. And none of the simple select queries
+  ** that make up the compound SELECT are allowed to be aggregate or distinct
+  ** queries.
+  */
+  if( pSub->pPrior ){
+    if( pSub->pOrderBy ){
+      return 0;  /* Restriction 20 */
+    }
+    if( isAgg || (p->selFlags & SF_Distinct)!=0 || pSrc->nSrc!=1 ){
+      return 0;
+    }
+    for(pSub1=pSub; pSub1; pSub1=pSub1->pPrior){
+      testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct );
+      testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Aggregate );
+      assert( pSub->pSrc!=0 );
+      assert( pSub->pEList->nExpr==pSub1->pEList->nExpr );
+      if( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))!=0
+       || (pSub1->pPrior && pSub1->op!=TK_ALL) 
+       || pSub1->pSrc->nSrc<1
+      ){
+        return 0;
+      }
+      testcase( pSub1->pSrc->nSrc>1 );
+    }
+
+    /* Restriction 18. */
+    if( p->pOrderBy ){
+      int ii;
+      for(ii=0; ii<p->pOrderBy->nExpr; ii++){
+        if( p->pOrderBy->a[ii].u.x.iOrderByCol==0 ) return 0;
+      }
+    }
+  }
+
+  /***** If we reach this point, flattening is permitted. *****/
+  SELECTTRACE(1,pParse,p,("flatten %s.%p from term %d\n",
+                   pSub->zSelName, pSub, iFrom));
+
+  /* Authorize the subquery */
+  pParse->zAuthContext = pSubitem->zName;
+  TESTONLY(i =) sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0);
+  testcase( i==SQLITE_DENY );
+  pParse->zAuthContext = zSavedAuthContext;
+
+  /* If the sub-query is a compound SELECT statement, then (by restrictions
+  ** 17 and 18 above) it must be a UNION ALL and the parent query must 
+  ** be of the form:
+  **
+  **     SELECT <expr-list> FROM (<sub-query>) <where-clause> 
+  **
+  ** followed by any ORDER BY, LIMIT and/or OFFSET clauses. This block
+  ** creates N-1 copies of the parent query without any ORDER BY, LIMIT or 
+  ** OFFSET clauses and joins them to the left-hand-side of the original
+  ** using UNION ALL operators. In this case N is the number of simple
+  ** select statements in the compound sub-query.
+  **
+  ** Example:
+  **
+  **     SELECT a+1 FROM (
+  **        SELECT x FROM tab
+  **        UNION ALL
+  **        SELECT y FROM tab
+  **        UNION ALL
+  **        SELECT abs(z*2) FROM tab2
+  **     ) WHERE a!=5 ORDER BY 1
+  **
+  ** Transformed into:
+  **
+  **     SELECT x+1 FROM tab WHERE x+1!=5
+  **     UNION ALL
+  **     SELECT y+1 FROM tab WHERE y+1!=5
+  **     UNION ALL
+  **     SELECT abs(z*2)+1 FROM tab2 WHERE abs(z*2)+1!=5
+  **     ORDER BY 1
+  **
+  ** We call this the "compound-subquery flattening".
+  */
+  for(pSub=pSub->pPrior; pSub; pSub=pSub->pPrior){
+    Select *pNew;
+    ExprList *pOrderBy = p->pOrderBy;
+    Expr *pLimit = p->pLimit;
+    Expr *pOffset = p->pOffset;
+    Select *pPrior = p->pPrior;
+    p->pOrderBy = 0;
+    p->pSrc = 0;
+    p->pPrior = 0;
+    p->pLimit = 0;
+    p->pOffset = 0;
+    pNew = sqlite3SelectDup(db, p, 0);
+    sqlite3SelectSetName(pNew, pSub->zSelName);
+    p->pOffset = pOffset;
+    p->pLimit = pLimit;
+    p->pOrderBy = pOrderBy;
+    p->pSrc = pSrc;
+    p->op = TK_ALL;
+    if( pNew==0 ){
+      p->pPrior = pPrior;
+    }else{
+      pNew->pPrior = pPrior;
+      if( pPrior ) pPrior->pNext = pNew;
+      pNew->pNext = p;
+      p->pPrior = pNew;
+      SELECTTRACE(2,pParse,p,
+         ("compound-subquery flattener creates %s.%p as peer\n",
+         pNew->zSelName, pNew));
+    }
+    if( db->mallocFailed ) return 1;
+  }
+
+  /* Begin flattening the iFrom-th entry of the FROM clause 
+  ** in the outer query.
+  */
+  pSub = pSub1 = pSubitem->pSelect;
+
+  /* Delete the transient table structure associated with the
+  ** subquery
+  */
+  sqlite3DbFree(db, pSubitem->zDatabase);
+  sqlite3DbFree(db, pSubitem->zName);
+  sqlite3DbFree(db, pSubitem->zAlias);
+  pSubitem->zDatabase = 0;
+  pSubitem->zName = 0;
+  pSubitem->zAlias = 0;
+  pSubitem->pSelect = 0;
+
+  /* Defer deleting the Table object associated with the
+  ** subquery until code generation is
+  ** complete, since there may still exist Expr.pTab entries that
+  ** refer to the subquery even after flattening.  Ticket #3346.
+  **
+  ** pSubitem->pTab is always non-NULL by test restrictions and tests above.
+  */
+  if( ALWAYS(pSubitem->pTab!=0) ){
+    Table *pTabToDel = pSubitem->pTab;
+    if( pTabToDel->nRef==1 ){
+      Parse *pToplevel = sqlite3ParseToplevel(pParse);
+      pTabToDel->pNextZombie = pToplevel->pZombieTab;
+      pToplevel->pZombieTab = pTabToDel;
+    }else{
+      pTabToDel->nRef--;
+    }
+    pSubitem->pTab = 0;
+  }
+
+  /* The following loop runs once for each term in a compound-subquery
+  ** flattening (as described above).  If we are doing a different kind
+  ** of flattening - a flattening other than a compound-subquery flattening -
+  ** then this loop only runs once.
+  **
+  ** This loop moves all of the FROM elements of the subquery into the
+  ** the FROM clause of the outer query.  Before doing this, remember
+  ** the cursor number for the original outer query FROM element in
+  ** iParent.  The iParent cursor will never be used.  Subsequent code
+  ** will scan expressions looking for iParent references and replace
+  ** those references with expressions that resolve to the subquery FROM
+  ** elements we are now copying in.
+  */
+  for(pParent=p; pParent; pParent=pParent->pPrior, pSub=pSub->pPrior){
+    int nSubSrc;
+    u8 jointype = 0;
+    pSubSrc = pSub->pSrc;     /* FROM clause of subquery */
+    nSubSrc = pSubSrc->nSrc;  /* Number of terms in subquery FROM clause */
+    pSrc = pParent->pSrc;     /* FROM clause of the outer query */
+
+    if( pSrc ){
+      assert( pParent==p );  /* First time through the loop */
+      jointype = pSubitem->fg.jointype;
+    }else{
+      assert( pParent!=p );  /* 2nd and subsequent times through the loop */
+      pSrc = pParent->pSrc = sqlite3SrcListAppend(db, 0, 0, 0);
+      if( pSrc==0 ){
+        assert( db->mallocFailed );
+        break;
+      }
+    }
+
+    /* The subquery uses a single slot of the FROM clause of the outer
+    ** query.  If the subquery has more than one element in its FROM clause,
+    ** then expand the outer query to make space for it to hold all elements
+    ** of the subquery.
+    **
+    ** Example:
+    **
+    **    SELECT * FROM tabA, (SELECT * FROM sub1, sub2), tabB;
+    **
+    ** The outer query has 3 slots in its FROM clause.  One slot of the
+    ** outer query (the middle slot) is used by the subquery.  The next
+    ** block of code will expand the outer query FROM clause to 4 slots.
+    ** The middle slot is expanded to two slots in order to make space
+    ** for the two elements in the FROM clause of the subquery.
+    */
+    if( nSubSrc>1 ){
+      pParent->pSrc = pSrc = sqlite3SrcListEnlarge(db, pSrc, nSubSrc-1,iFrom+1);
+      if( db->mallocFailed ){
+        break;
+      }
+    }
+
+    /* Transfer the FROM clause terms from the subquery into the
+    ** outer query.
+    */
+    for(i=0; i<nSubSrc; i++){
+      sqlite3IdListDelete(db, pSrc->a[i+iFrom].pUsing);
+      assert( pSrc->a[i+iFrom].fg.isTabFunc==0 );
+      pSrc->a[i+iFrom] = pSubSrc->a[i];
+      memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i]));
+    }
+    pSrc->a[iFrom].fg.jointype = jointype;
+  
+    /* Now begin substituting subquery result set expressions for 
+    ** references to the iParent in the outer query.
+    ** 
+    ** Example:
+    **
+    **   SELECT a+5, b*10 FROM (SELECT x*3 AS a, y+10 AS b FROM t1) WHERE a>b;
+    **   \                     \_____________ subquery __________/          /
+    **    \_____________________ outer query ______________________________/
+    **
+    ** We look at every expression in the outer query and every place we see
+    ** "a" we substitute "x*3" and every place we see "b" we substitute "y+10".
+    */
+    pList = pParent->pEList;
+    for(i=0; i<pList->nExpr; i++){
+      if( pList->a[i].zName==0 ){
+        char *zName = sqlite3DbStrDup(db, pList->a[i].zSpan);
+        sqlite3Dequote(zName);
+        pList->a[i].zName = zName;
+      }
+    }
+    if( pSub->pOrderBy ){
+      /* At this point, any non-zero iOrderByCol values indicate that the
+      ** ORDER BY column expression is identical to the iOrderByCol'th
+      ** expression returned by SELECT statement pSub. Since these values
+      ** do not necessarily correspond to columns in SELECT statement pParent,
+      ** zero them before transfering the ORDER BY clause.
+      **
+      ** Not doing this may cause an error if a subsequent call to this
+      ** function attempts to flatten a compound sub-query into pParent
+      ** (the only way this can happen is if the compound sub-query is
+      ** currently part of pSub->pSrc). See ticket [d11a6e908f].  */
+      ExprList *pOrderBy = pSub->pOrderBy;
+      for(i=0; i<pOrderBy->nExpr; i++){
+        pOrderBy->a[i].u.x.iOrderByCol = 0;
+      }
+      assert( pParent->pOrderBy==0 );
+      assert( pSub->pPrior==0 );
+      pParent->pOrderBy = pOrderBy;
+      pSub->pOrderBy = 0;
+    }
+    pWhere = sqlite3ExprDup(db, pSub->pWhere, 0);
+    if( subqueryIsAgg ){
+      assert( pParent->pHaving==0 );
+      pParent->pHaving = pParent->pWhere;
+      pParent->pWhere = pWhere;
+      pParent->pHaving = sqlite3ExprAnd(db, 
+          sqlite3ExprDup(db, pSub->pHaving, 0), pParent->pHaving
+      );
+      assert( pParent->pGroupBy==0 );
+      pParent->pGroupBy = sqlite3ExprListDup(db, pSub->pGroupBy, 0);
+    }else{
+      pParent->pWhere = sqlite3ExprAnd(db, pWhere, pParent->pWhere);
+    }
+    substSelect(db, pParent, iParent, pSub->pEList, 0);
+  
+    /* The flattened query is distinct if either the inner or the
+    ** outer query is distinct. 
+    */
+    pParent->selFlags |= pSub->selFlags & SF_Distinct;
+  
+    /*
+    ** SELECT ... FROM (SELECT ... LIMIT a OFFSET b) LIMIT x OFFSET y;
+    **
+    ** One is tempted to try to add a and b to combine the limits.  But this
+    ** does not work if either limit is negative.
+    */
+    if( pSub->pLimit ){
+      pParent->pLimit = pSub->pLimit;
+      pSub->pLimit = 0;
+    }
+  }
+
+  /* Finially, delete what is left of the subquery and return
+  ** success.
+  */
+  sqlite3SelectDelete(db, pSub1);
+
+#if SELECTTRACE_ENABLED
+  if( sqlite3SelectTrace & 0x100 ){
+    SELECTTRACE(0x100,pParse,p,("After flattening:\n"));
+    sqlite3TreeViewSelect(0, p, 0);
+  }
+#endif
+
+  return 1;
+}
+#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
+
+
+
+#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
+/*
+** Make copies of relevant WHERE clause terms of the outer query into
+** the WHERE clause of subquery.  Example:
+**
+**    SELECT * FROM (SELECT a AS x, c-d AS y FROM t1) WHERE x=5 AND y=10;
+**
+** Transformed into:
+**
+**    SELECT * FROM (SELECT a AS x, c-d AS y FROM t1 WHERE a=5 AND c-d=10)
+**     WHERE x=5 AND y=10;
+**
+** The hope is that the terms added to the inner query will make it more
+** efficient.
+**
+** Do not attempt this optimization if:
+**
+**   (1) The inner query is an aggregate.  (In that case, we'd really want
+**       to copy the outer WHERE-clause terms onto the HAVING clause of the
+**       inner query.  But they probably won't help there so do not bother.)
+**
+**   (2) The inner query is the recursive part of a common table expression.
+**
+**   (3) The inner query has a LIMIT clause (since the changes to the WHERE
+**       close would change the meaning of the LIMIT).
+**
+**   (4) The inner query is the right operand of a LEFT JOIN.  (The caller
+**       enforces this restriction since this routine does not have enough
+**       information to know.)
+**
+**   (5) The WHERE clause expression originates in the ON or USING clause
+**       of a LEFT JOIN.
+**
+** Return 0 if no changes are made and non-zero if one or more WHERE clause
+** terms are duplicated into the subquery.
+*/
+static int pushDownWhereTerms(
+  sqlite3 *db,          /* The database connection (for malloc()) */
+  Select *pSubq,        /* The subquery whose WHERE clause is to be augmented */
+  Expr *pWhere,         /* The WHERE clause of the outer query */
+  int iCursor           /* Cursor number of the subquery */
+){
+  Expr *pNew;
+  int nChng = 0;
+  Select *pX;           /* For looping over compound SELECTs in pSubq */
+  if( pWhere==0 ) return 0;
+  for(pX=pSubq; pX; pX=pX->pPrior){
+    if( (pX->selFlags & (SF_Aggregate|SF_Recursive))!=0 ){
+      testcase( pX->selFlags & SF_Aggregate );
+      testcase( pX->selFlags & SF_Recursive );
+      testcase( pX!=pSubq );
+      return 0; /* restrictions (1) and (2) */
+    }
+  }
+  if( pSubq->pLimit!=0 ){
+    return 0; /* restriction (3) */
+  }
+  while( pWhere->op==TK_AND ){
+    nChng += pushDownWhereTerms(db, pSubq, pWhere->pRight, iCursor);
+    pWhere = pWhere->pLeft;
+  }
+  if( ExprHasProperty(pWhere,EP_FromJoin) ) return 0; /* restriction 5 */
+  if( sqlite3ExprIsTableConstant(pWhere, iCursor) ){
+    nChng++;
+    while( pSubq ){
+      pNew = sqlite3ExprDup(db, pWhere, 0);
+      pNew = substExpr(db, pNew, iCursor, pSubq->pEList);
+      pSubq->pWhere = sqlite3ExprAnd(db, pSubq->pWhere, pNew);
+      pSubq = pSubq->pPrior;
+    }
+  }
+  return nChng;
+}
+#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
+
+/*
+** Based on the contents of the AggInfo structure indicated by the first
+** argument, this function checks if the following are true:
+**
+**    * the query contains just a single aggregate function,
+**    * the aggregate function is either min() or max(), and
+**    * the argument to the aggregate function is a column value.
+**
+** If all of the above are true, then WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX
+** is returned as appropriate. Also, *ppMinMax is set to point to the 
+** list of arguments passed to the aggregate before returning.
+**
+** Or, if the conditions above are not met, *ppMinMax is set to 0 and
+** WHERE_ORDERBY_NORMAL is returned.
+*/
+static u8 minMaxQuery(AggInfo *pAggInfo, ExprList **ppMinMax){
+  int eRet = WHERE_ORDERBY_NORMAL;          /* Return value */
+
+  *ppMinMax = 0;
+  if( pAggInfo->nFunc==1 ){
+    Expr *pExpr = pAggInfo->aFunc[0].pExpr; /* Aggregate function */
+    ExprList *pEList = pExpr->x.pList;      /* Arguments to agg function */
+
+    assert( pExpr->op==TK_AGG_FUNCTION );
+    if( pEList && pEList->nExpr==1 && pEList->a[0].pExpr->op==TK_AGG_COLUMN ){
+      const char *zFunc = pExpr->u.zToken;
+      if( sqlite3StrICmp(zFunc, "min")==0 ){
+        eRet = WHERE_ORDERBY_MIN;
+        *ppMinMax = pEList;
+      }else if( sqlite3StrICmp(zFunc, "max")==0 ){
+        eRet = WHERE_ORDERBY_MAX;
+        *ppMinMax = pEList;
+      }
+    }
+  }
+
+  assert( *ppMinMax==0 || (*ppMinMax)->nExpr==1 );
+  return eRet;
+}
+
+/*
+** The select statement passed as the first argument is an aggregate query.
+** The second argument is the associated aggregate-info object. This 
+** function tests if the SELECT is of the form:
+**
+**   SELECT count(*) FROM <tbl>
+**
+** where table is a database table, not a sub-select or view. If the query
+** does match this pattern, then a pointer to the Table object representing
+** <tbl> is returned. Otherwise, 0 is returned.
+*/
+static Table *isSimpleCount(Select *p, AggInfo *pAggInfo){
+  Table *pTab;
+  Expr *pExpr;
+
+  assert( !p->pGroupBy );
+
+  if( p->pWhere || p->pEList->nExpr!=1 
+   || p->pSrc->nSrc!=1 || p->pSrc->a[0].pSelect
+  ){
+    return 0;
+  }
+  pTab = p->pSrc->a[0].pTab;
+  pExpr = p->pEList->a[0].pExpr;
+  assert( pTab && !pTab->pSelect && pExpr );
+
+  if( IsVirtual(pTab) ) return 0;
+  if( pExpr->op!=TK_AGG_FUNCTION ) return 0;
+  if( NEVER(pAggInfo->nFunc==0) ) return 0;
+  if( (pAggInfo->aFunc[0].pFunc->funcFlags&SQLITE_FUNC_COUNT)==0 ) return 0;
+  if( pExpr->flags&EP_Distinct ) return 0;
+
+  return pTab;
+}
+
+/*
+** If the source-list item passed as an argument was augmented with an
+** INDEXED BY clause, then try to locate the specified index. If there
+** was such a clause and the named index cannot be found, return 
+** SQLITE_ERROR and leave an error in pParse. Otherwise, populate 
+** pFrom->pIndex and return SQLITE_OK.
+*/
+SQLITE_PRIVATE int sqlite3IndexedByLookup(Parse *pParse, struct SrcList_item *pFrom){
+  if( pFrom->pTab && pFrom->fg.isIndexedBy ){
+    Table *pTab = pFrom->pTab;
+    char *zIndexedBy = pFrom->u1.zIndexedBy;
+    Index *pIdx;
+    for(pIdx=pTab->pIndex; 
+        pIdx && sqlite3StrICmp(pIdx->zName, zIndexedBy); 
+        pIdx=pIdx->pNext
+    );
+    if( !pIdx ){
+      sqlite3ErrorMsg(pParse, "no such index: %s", zIndexedBy, 0);
+      pParse->checkSchema = 1;
+      return SQLITE_ERROR;
+    }
+    pFrom->pIBIndex = pIdx;
+  }
+  return SQLITE_OK;
+}
+/*
+** Detect compound SELECT statements that use an ORDER BY clause with 
+** an alternative collating sequence.
+**
+**    SELECT ... FROM t1 EXCEPT SELECT ... FROM t2 ORDER BY .. COLLATE ...
+**
+** These are rewritten as a subquery:
+**
+**    SELECT * FROM (SELECT ... FROM t1 EXCEPT SELECT ... FROM t2)
+**     ORDER BY ... COLLATE ...
+**
+** This transformation is necessary because the multiSelectOrderBy() routine
+** above that generates the code for a compound SELECT with an ORDER BY clause
+** uses a merge algorithm that requires the same collating sequence on the
+** result columns as on the ORDER BY clause.  See ticket
+** http://www.sqlite.org/src/info/6709574d2a
+**
+** This transformation is only needed for EXCEPT, INTERSECT, and UNION.
+** The UNION ALL operator works fine with multiSelectOrderBy() even when
+** there are COLLATE terms in the ORDER BY.
+*/
+static int convertCompoundSelectToSubquery(Walker *pWalker, Select *p){
+  int i;
+  Select *pNew;
+  Select *pX;
+  sqlite3 *db;
+  struct ExprList_item *a;
+  SrcList *pNewSrc;
+  Parse *pParse;
+  Token dummy;
+
+  if( p->pPrior==0 ) return WRC_Continue;
+  if( p->pOrderBy==0 ) return WRC_Continue;
+  for(pX=p; pX && (pX->op==TK_ALL || pX->op==TK_SELECT); pX=pX->pPrior){}
+  if( pX==0 ) return WRC_Continue;
+  a = p->pOrderBy->a;
+  for(i=p->pOrderBy->nExpr-1; i>=0; i--){
+    if( a[i].pExpr->flags & EP_Collate ) break;
+  }
+  if( i<0 ) return WRC_Continue;
+
+  /* If we reach this point, that means the transformation is required. */
+
+  pParse = pWalker->pParse;
+  db = pParse->db;
+  pNew = sqlite3DbMallocZero(db, sizeof(*pNew) );
+  if( pNew==0 ) return WRC_Abort;
+  memset(&dummy, 0, sizeof(dummy));
+  pNewSrc = sqlite3SrcListAppendFromTerm(pParse,0,0,0,&dummy,pNew,0,0);
+  if( pNewSrc==0 ) return WRC_Abort;
+  *pNew = *p;
+  p->pSrc = pNewSrc;
+  p->pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db, TK_ASTERISK, 0));
+  p->op = TK_SELECT;
+  p->pWhere = 0;
+  pNew->pGroupBy = 0;
+  pNew->pHaving = 0;
+  pNew->pOrderBy = 0;
+  p->pPrior = 0;
+  p->pNext = 0;
+  p->pWith = 0;
+  p->selFlags &= ~SF_Compound;
+  assert( (p->selFlags & SF_Converted)==0 );
+  p->selFlags |= SF_Converted;
+  assert( pNew->pPrior!=0 );
+  pNew->pPrior->pNext = pNew;
+  pNew->pLimit = 0;
+  pNew->pOffset = 0;
+  return WRC_Continue;
+}
+
+/*
+** Check to see if the FROM clause term pFrom has table-valued function
+** arguments.  If it does, leave an error message in pParse and return
+** non-zero, since pFrom is not allowed to be a table-valued function.
+*/
+static int cannotBeFunction(Parse *pParse, struct SrcList_item *pFrom){
+  if( pFrom->fg.isTabFunc ){
+    sqlite3ErrorMsg(pParse, "'%s' is not a function", pFrom->zName);
+    return 1;
+  }
+  return 0;
+}
+
+#ifndef SQLITE_OMIT_CTE
+/*
+** Argument pWith (which may be NULL) points to a linked list of nested 
+** WITH contexts, from inner to outermost. If the table identified by 
+** FROM clause element pItem is really a common-table-expression (CTE) 
+** then return a pointer to the CTE definition for that table. Otherwise
+** return NULL.
+**
+** If a non-NULL value is returned, set *ppContext to point to the With
+** object that the returned CTE belongs to.
+*/
+static struct Cte *searchWith(
+  With *pWith,                    /* Current innermost WITH clause */
+  struct SrcList_item *pItem,     /* FROM clause element to resolve */
+  With **ppContext                /* OUT: WITH clause return value belongs to */
+){
+  const char *zName;
+  if( pItem->zDatabase==0 && (zName = pItem->zName)!=0 ){
+    With *p;
+    for(p=pWith; p; p=p->pOuter){
+      int i;
+      for(i=0; i<p->nCte; i++){
+        if( sqlite3StrICmp(zName, p->a[i].zName)==0 ){
+          *ppContext = p;
+          return &p->a[i];
+        }
+      }
+    }
+  }
+  return 0;
+}
+
+/* The code generator maintains a stack of active WITH clauses
+** with the inner-most WITH clause being at the top of the stack.
+**
+** This routine pushes the WITH clause passed as the second argument
+** onto the top of the stack. If argument bFree is true, then this
+** WITH clause will never be popped from the stack. In this case it
+** should be freed along with the Parse object. In other cases, when
+** bFree==0, the With object will be freed along with the SELECT 
+** statement with which it is associated.
+*/
+SQLITE_PRIVATE void sqlite3WithPush(Parse *pParse, With *pWith, u8 bFree){
+  assert( bFree==0 || (pParse->pWith==0 && pParse->pWithToFree==0) );
+  if( pWith ){
+    assert( pParse->pWith!=pWith );
+    pWith->pOuter = pParse->pWith;
+    pParse->pWith = pWith;
+    if( bFree ) pParse->pWithToFree = pWith;
+  }
+}
+
+/*
+** This function checks if argument pFrom refers to a CTE declared by 
+** a WITH clause on the stack currently maintained by the parser. And,
+** if currently processing a CTE expression, if it is a recursive
+** reference to the current CTE.
+**
+** If pFrom falls into either of the two categories above, pFrom->pTab
+** and other fields are populated accordingly. The caller should check
+** (pFrom->pTab!=0) to determine whether or not a successful match
+** was found.
+**
+** Whether or not a match is found, SQLITE_OK is returned if no error
+** occurs. If an error does occur, an error message is stored in the
+** parser and some error code other than SQLITE_OK returned.
+*/
+static int withExpand(
+  Walker *pWalker, 
+  struct SrcList_item *pFrom
+){
+  Parse *pParse = pWalker->pParse;
+  sqlite3 *db = pParse->db;
+  struct Cte *pCte;               /* Matched CTE (or NULL if no match) */
+  With *pWith;                    /* WITH clause that pCte belongs to */
+
+  assert( pFrom->pTab==0 );
+
+  pCte = searchWith(pParse->pWith, pFrom, &pWith);
+  if( pCte ){
+    Table *pTab;
+    ExprList *pEList;
+    Select *pSel;
+    Select *pLeft;                /* Left-most SELECT statement */
+    int bMayRecursive;            /* True if compound joined by UNION [ALL] */
+    With *pSavedWith;             /* Initial value of pParse->pWith */
+
+    /* If pCte->zCteErr is non-NULL at this point, then this is an illegal
+    ** recursive reference to CTE pCte. Leave an error in pParse and return
+    ** early. If pCte->zCteErr is NULL, then this is not a recursive reference.
+    ** In this case, proceed.  */
+    if( pCte->zCteErr ){
+      sqlite3ErrorMsg(pParse, pCte->zCteErr, pCte->zName);
+      return SQLITE_ERROR;
+    }
+    if( cannotBeFunction(pParse, pFrom) ) return SQLITE_ERROR;
+
+    assert( pFrom->pTab==0 );
+    pFrom->pTab = pTab = sqlite3DbMallocZero(db, sizeof(Table));
+    if( pTab==0 ) return WRC_Abort;
+    pTab->nRef = 1;
+    pTab->zName = sqlite3DbStrDup(db, pCte->zName);
+    pTab->iPKey = -1;
+    pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) );
+    pTab->tabFlags |= TF_Ephemeral | TF_NoVisibleRowid;
+    pFrom->pSelect = sqlite3SelectDup(db, pCte->pSelect, 0);
+    if( db->mallocFailed ) return SQLITE_NOMEM_BKPT;
+    assert( pFrom->pSelect );
+
+    /* Check if this is a recursive CTE. */
+    pSel = pFrom->pSelect;
+    bMayRecursive = ( pSel->op==TK_ALL || pSel->op==TK_UNION );
+    if( bMayRecursive ){
+      int i;
+      SrcList *pSrc = pFrom->pSelect->pSrc;
+      for(i=0; i<pSrc->nSrc; i++){
+        struct SrcList_item *pItem = &pSrc->a[i];
+        if( pItem->zDatabase==0 
+         && pItem->zName!=0 
+         && 0==sqlite3StrICmp(pItem->zName, pCte->zName)
+          ){
+          pItem->pTab = pTab;
+          pItem->fg.isRecursive = 1;
+          pTab->nRef++;
+          pSel->selFlags |= SF_Recursive;
+        }
+      }
+    }
+
+    /* Only one recursive reference is permitted. */ 
+    if( pTab->nRef>2 ){
+      sqlite3ErrorMsg(
+          pParse, "multiple references to recursive table: %s", pCte->zName
+      );
+      return SQLITE_ERROR;
+    }
+    assert( pTab->nRef==1 || ((pSel->selFlags&SF_Recursive) && pTab->nRef==2 ));
+
+    pCte->zCteErr = "circular reference: %s";
+    pSavedWith = pParse->pWith;
+    pParse->pWith = pWith;
+    sqlite3WalkSelect(pWalker, bMayRecursive ? pSel->pPrior : pSel);
+    pParse->pWith = pWith;
+
+    for(pLeft=pSel; pLeft->pPrior; pLeft=pLeft->pPrior);
+    pEList = pLeft->pEList;
+    if( pCte->pCols ){
+      if( pEList && pEList->nExpr!=pCte->pCols->nExpr ){
+        sqlite3ErrorMsg(pParse, "table %s has %d values for %d columns",
+            pCte->zName, pEList->nExpr, pCte->pCols->nExpr
+        );
+        pParse->pWith = pSavedWith;
+        return SQLITE_ERROR;
+      }
+      pEList = pCte->pCols;
+    }
+
+    sqlite3ColumnsFromExprList(pParse, pEList, &pTab->nCol, &pTab->aCol);
+    if( bMayRecursive ){
+      if( pSel->selFlags & SF_Recursive ){
+        pCte->zCteErr = "multiple recursive references: %s";
+      }else{
+        pCte->zCteErr = "recursive reference in a subquery: %s";
+      }
+      sqlite3WalkSelect(pWalker, pSel);
+    }
+    pCte->zCteErr = 0;
+    pParse->pWith = pSavedWith;
+  }
+
+  return SQLITE_OK;
+}
+#endif
+
+#ifndef SQLITE_OMIT_CTE
+/*
+** If the SELECT passed as the second argument has an associated WITH 
+** clause, pop it from the stack stored as part of the Parse object.
+**
+** This function is used as the xSelectCallback2() callback by
+** sqlite3SelectExpand() when walking a SELECT tree to resolve table
+** names and other FROM clause elements. 
+*/
+static void selectPopWith(Walker *pWalker, Select *p){
+  Parse *pParse = pWalker->pParse;
+  With *pWith = findRightmost(p)->pWith;
+  if( pWith!=0 ){
+    assert( pParse->pWith==pWith );
+    pParse->pWith = pWith->pOuter;
+  }
+}
+#else
+#define selectPopWith 0
+#endif
+
+/*
+** This routine is a Walker callback for "expanding" a SELECT statement.
+** "Expanding" means to do the following:
+**
+**    (1)  Make sure VDBE cursor numbers have been assigned to every
+**         element of the FROM clause.
+**
+**    (2)  Fill in the pTabList->a[].pTab fields in the SrcList that 
+**         defines FROM clause.  When views appear in the FROM clause,
+**         fill pTabList->a[].pSelect with a copy of the SELECT statement
+**         that implements the view.  A copy is made of the view's SELECT
+**         statement so that we can freely modify or delete that statement
+**         without worrying about messing up the persistent representation
+**         of the view.
+**
+**    (3)  Add terms to the WHERE clause to accommodate the NATURAL keyword
+**         on joins and the ON and USING clause of joins.
+**
+**    (4)  Scan the list of columns in the result set (pEList) looking
+**         for instances of the "*" operator or the TABLE.* operator.
+**         If found, expand each "*" to be every column in every table
+**         and TABLE.* to be every column in TABLE.
+**
+*/
+static int selectExpander(Walker *pWalker, Select *p){
+  Parse *pParse = pWalker->pParse;
+  int i, j, k;
+  SrcList *pTabList;
+  ExprList *pEList;
+  struct SrcList_item *pFrom;
+  sqlite3 *db = pParse->db;
+  Expr *pE, *pRight, *pExpr;
+  u16 selFlags = p->selFlags;
+
+  p->selFlags |= SF_Expanded;
+  if( db->mallocFailed  ){
+    return WRC_Abort;
+  }
+  if( NEVER(p->pSrc==0) || (selFlags & SF_Expanded)!=0 ){
+    return WRC_Prune;
+  }
+  pTabList = p->pSrc;
+  pEList = p->pEList;
+  if( pWalker->xSelectCallback2==selectPopWith ){
+    sqlite3WithPush(pParse, findRightmost(p)->pWith, 0);
+  }
+
+  /* Make sure cursor numbers have been assigned to all entries in
+  ** the FROM clause of the SELECT statement.
+  */
+  sqlite3SrcListAssignCursors(pParse, pTabList);
+
+  /* Look up every table named in the FROM clause of the select.  If
+  ** an entry of the FROM clause is a subquery instead of a table or view,
+  ** then create a transient table structure to describe the subquery.
+  */
+  for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
+    Table *pTab;
+    assert( pFrom->fg.isRecursive==0 || pFrom->pTab!=0 );
+    if( pFrom->fg.isRecursive ) continue;
+    assert( pFrom->pTab==0 );
+#ifndef SQLITE_OMIT_CTE
+    if( withExpand(pWalker, pFrom) ) return WRC_Abort;
+    if( pFrom->pTab ) {} else
+#endif
+    if( pFrom->zName==0 ){
+#ifndef SQLITE_OMIT_SUBQUERY
+      Select *pSel = pFrom->pSelect;
+      /* A sub-query in the FROM clause of a SELECT */
+      assert( pSel!=0 );
+      assert( pFrom->pTab==0 );
+      if( sqlite3WalkSelect(pWalker, pSel) ) return WRC_Abort;
+      pFrom->pTab = pTab = sqlite3DbMallocZero(db, sizeof(Table));
+      if( pTab==0 ) return WRC_Abort;
+      pTab->nRef = 1;
+      pTab->zName = sqlite3MPrintf(db, "sqlite_sq_%p", (void*)pTab);
+      while( pSel->pPrior ){ pSel = pSel->pPrior; }
+      sqlite3ColumnsFromExprList(pParse, pSel->pEList,&pTab->nCol,&pTab->aCol);
+      pTab->iPKey = -1;
+      pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) );
+      pTab->tabFlags |= TF_Ephemeral;
+#endif
+    }else{
+      /* An ordinary table or view name in the FROM clause */
+      assert( pFrom->pTab==0 );
+      pFrom->pTab = pTab = sqlite3LocateTableItem(pParse, 0, pFrom);
+      if( pTab==0 ) return WRC_Abort;
+      if( pTab->nRef==0xffff ){
+        sqlite3ErrorMsg(pParse, "too many references to \"%s\": max 65535",
+           pTab->zName);
+        pFrom->pTab = 0;
+        return WRC_Abort;
+      }
+      pTab->nRef++;
+      if( !IsVirtual(pTab) && cannotBeFunction(pParse, pFrom) ){
+        return WRC_Abort;
+      }
+#if !defined(SQLITE_OMIT_VIEW) || !defined (SQLITE_OMIT_VIRTUALTABLE)
+      if( IsVirtual(pTab) || pTab->pSelect ){
+        i16 nCol;
+        if( sqlite3ViewGetColumnNames(pParse, pTab) ) return WRC_Abort;
+        assert( pFrom->pSelect==0 );
+        pFrom->pSelect = sqlite3SelectDup(db, pTab->pSelect, 0);
+        sqlite3SelectSetName(pFrom->pSelect, pTab->zName);
+        nCol = pTab->nCol;
+        pTab->nCol = -1;
+        sqlite3WalkSelect(pWalker, pFrom->pSelect);
+        pTab->nCol = nCol;
+      }
+#endif
+    }
+
+    /* Locate the index named by the INDEXED BY clause, if any. */
+    if( sqlite3IndexedByLookup(pParse, pFrom) ){
+      return WRC_Abort;
+    }
+  }
+
+  /* Process NATURAL keywords, and ON and USING clauses of joins.
+  */
+  if( db->mallocFailed || sqliteProcessJoin(pParse, p) ){
+    return WRC_Abort;
+  }
+
+  /* For every "*" that occurs in the column list, insert the names of
+  ** all columns in all tables.  And for every TABLE.* insert the names
+  ** of all columns in TABLE.  The parser inserted a special expression
+  ** with the TK_ASTERISK operator for each "*" that it found in the column
+  ** list.  The following code just has to locate the TK_ASTERISK
+  ** expressions and expand each one to the list of all columns in
+  ** all tables.
+  **
+  ** The first loop just checks to see if there are any "*" operators
+  ** that need expanding.
+  */
+  for(k=0; k<pEList->nExpr; k++){
+    pE = pEList->a[k].pExpr;
+    if( pE->op==TK_ASTERISK ) break;
+    assert( pE->op!=TK_DOT || pE->pRight!=0 );
+    assert( pE->op!=TK_DOT || (pE->pLeft!=0 && pE->pLeft->op==TK_ID) );
+    if( pE->op==TK_DOT && pE->pRight->op==TK_ASTERISK ) break;
+  }
+  if( k<pEList->nExpr ){
+    /*
+    ** If we get here it means the result set contains one or more "*"
+    ** operators that need to be expanded.  Loop through each expression
+    ** in the result set and expand them one by one.
+    */
+    struct ExprList_item *a = pEList->a;
+    ExprList *pNew = 0;
+    int flags = pParse->db->flags;
+    int longNames = (flags & SQLITE_FullColNames)!=0
+                      && (flags & SQLITE_ShortColNames)==0;
+
+    for(k=0; k<pEList->nExpr; k++){
+      pE = a[k].pExpr;
+      pRight = pE->pRight;
+      assert( pE->op!=TK_DOT || pRight!=0 );
+      if( pE->op!=TK_ASTERISK
+       && (pE->op!=TK_DOT || pRight->op!=TK_ASTERISK)
+      ){
+        /* This particular expression does not need to be expanded.
+        */
+        pNew = sqlite3ExprListAppend(pParse, pNew, a[k].pExpr);
+        if( pNew ){
+          pNew->a[pNew->nExpr-1].zName = a[k].zName;
+          pNew->a[pNew->nExpr-1].zSpan = a[k].zSpan;
+          a[k].zName = 0;
+          a[k].zSpan = 0;
+        }
+        a[k].pExpr = 0;
+      }else{
+        /* This expression is a "*" or a "TABLE.*" and needs to be
+        ** expanded. */
+        int tableSeen = 0;      /* Set to 1 when TABLE matches */
+        char *zTName = 0;       /* text of name of TABLE */
+        if( pE->op==TK_DOT ){
+          assert( pE->pLeft!=0 );
+          assert( !ExprHasProperty(pE->pLeft, EP_IntValue) );
+          zTName = pE->pLeft->u.zToken;
+        }
+        for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
+          Table *pTab = pFrom->pTab;
+          Select *pSub = pFrom->pSelect;
+          char *zTabName = pFrom->zAlias;
+          const char *zSchemaName = 0;
+          int iDb;
+          if( zTabName==0 ){
+            zTabName = pTab->zName;
+          }
+          if( db->mallocFailed ) break;
+          if( pSub==0 || (pSub->selFlags & SF_NestedFrom)==0 ){
+            pSub = 0;
+            if( zTName && sqlite3StrICmp(zTName, zTabName)!=0 ){
+              continue;
+            }
+            iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+            zSchemaName = iDb>=0 ? db->aDb[iDb].zDbSName : "*";
+          }
+          for(j=0; j<pTab->nCol; j++){
+            char *zName = pTab->aCol[j].zName;
+            char *zColname;  /* The computed column name */
+            char *zToFree;   /* Malloced string that needs to be freed */
+            Token sColname;  /* Computed column name as a token */
+
+            assert( zName );
+            if( zTName && pSub
+             && sqlite3MatchSpanName(pSub->pEList->a[j].zSpan, 0, zTName, 0)==0
+            ){
+              continue;
+            }
+
+            /* If a column is marked as 'hidden', omit it from the expanded
+            ** result-set list unless the SELECT has the SF_IncludeHidden
+            ** bit set.
+            */
+            if( (p->selFlags & SF_IncludeHidden)==0
+             && IsHiddenColumn(&pTab->aCol[j]) 
+            ){
+              continue;
+            }
+            tableSeen = 1;
+
+            if( i>0 && zTName==0 ){
+              if( (pFrom->fg.jointype & JT_NATURAL)!=0
+                && tableAndColumnIndex(pTabList, i, zName, 0, 0)
+              ){
+                /* In a NATURAL join, omit the join columns from the 
+                ** table to the right of the join */
+                continue;
+              }
+              if( sqlite3IdListIndex(pFrom->pUsing, zName)>=0 ){
+                /* In a join with a USING clause, omit columns in the
+                ** using clause from the table on the right. */
+                continue;
+              }
+            }
+            pRight = sqlite3Expr(db, TK_ID, zName);
+            zColname = zName;
+            zToFree = 0;
+            if( longNames || pTabList->nSrc>1 ){
+              Expr *pLeft;
+              pLeft = sqlite3Expr(db, TK_ID, zTabName);
+              pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pRight, 0);
+              if( zSchemaName ){
+                pLeft = sqlite3Expr(db, TK_ID, zSchemaName);
+                pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pExpr, 0);
+              }
+              if( longNames ){
+                zColname = sqlite3MPrintf(db, "%s.%s", zTabName, zName);
+                zToFree = zColname;
+              }
+            }else{
+              pExpr = pRight;
+            }
+            pNew = sqlite3ExprListAppend(pParse, pNew, pExpr);
+            sqlite3TokenInit(&sColname, zColname);
+            sqlite3ExprListSetName(pParse, pNew, &sColname, 0);
+            if( pNew && (p->selFlags & SF_NestedFrom)!=0 ){
+              struct ExprList_item *pX = &pNew->a[pNew->nExpr-1];
+              if( pSub ){
+                pX->zSpan = sqlite3DbStrDup(db, pSub->pEList->a[j].zSpan);
+                testcase( pX->zSpan==0 );
+              }else{
+                pX->zSpan = sqlite3MPrintf(db, "%s.%s.%s",
+                                           zSchemaName, zTabName, zColname);
+                testcase( pX->zSpan==0 );
+              }
+              pX->bSpanIsTab = 1;
+            }
+            sqlite3DbFree(db, zToFree);
+          }
+        }
+        if( !tableSeen ){
+          if( zTName ){
+            sqlite3ErrorMsg(pParse, "no such table: %s", zTName);
+          }else{
+            sqlite3ErrorMsg(pParse, "no tables specified");
+          }
+        }
+      }
+    }
+    sqlite3ExprListDelete(db, pEList);
+    p->pEList = pNew;
+  }
+#if SQLITE_MAX_COLUMN
+  if( p->pEList && p->pEList->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){
+    sqlite3ErrorMsg(pParse, "too many columns in result set");
+    return WRC_Abort;
+  }
+#endif
+  return WRC_Continue;
+}
+
+/*
+** No-op routine for the parse-tree walker.
+**
+** When this routine is the Walker.xExprCallback then expression trees
+** are walked without any actions being taken at each node.  Presumably,
+** when this routine is used for Walker.xExprCallback then 
+** Walker.xSelectCallback is set to do something useful for every 
+** subquery in the parser tree.
+*/
+SQLITE_PRIVATE int sqlite3ExprWalkNoop(Walker *NotUsed, Expr *NotUsed2){
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  return WRC_Continue;
+}
+
+/*
+** This routine "expands" a SELECT statement and all of its subqueries.
+** For additional information on what it means to "expand" a SELECT
+** statement, see the comment on the selectExpand worker callback above.
+**
+** Expanding a SELECT statement is the first step in processing a
+** SELECT statement.  The SELECT statement must be expanded before
+** name resolution is performed.
+**
+** If anything goes wrong, an error message is written into pParse.
+** The calling function can detect the problem by looking at pParse->nErr
+** and/or pParse->db->mallocFailed.
+*/
+static void sqlite3SelectExpand(Parse *pParse, Select *pSelect){
+  Walker w;
+  memset(&w, 0, sizeof(w));
+  w.xExprCallback = sqlite3ExprWalkNoop;
+  w.pParse = pParse;
+  if( pParse->hasCompound ){
+    w.xSelectCallback = convertCompoundSelectToSubquery;
+    sqlite3WalkSelect(&w, pSelect);
+  }
+  w.xSelectCallback = selectExpander;
+  if( (pSelect->selFlags & SF_MultiValue)==0 ){
+    w.xSelectCallback2 = selectPopWith;
+  }
+  sqlite3WalkSelect(&w, pSelect);
+}
+
+
+#ifndef SQLITE_OMIT_SUBQUERY
+/*
+** This is a Walker.xSelectCallback callback for the sqlite3SelectTypeInfo()
+** interface.
+**
+** For each FROM-clause subquery, add Column.zType and Column.zColl
+** information to the Table structure that represents the result set
+** of that subquery.
+**
+** The Table structure that represents the result set was constructed
+** by selectExpander() but the type and collation information was omitted
+** at that point because identifiers had not yet been resolved.  This
+** routine is called after identifier resolution.
+*/
+static void selectAddSubqueryTypeInfo(Walker *pWalker, Select *p){
+  Parse *pParse;
+  int i;
+  SrcList *pTabList;
+  struct SrcList_item *pFrom;
+
+  assert( p->selFlags & SF_Resolved );
+  assert( (p->selFlags & SF_HasTypeInfo)==0 );
+  p->selFlags |= SF_HasTypeInfo;
+  pParse = pWalker->pParse;
+  pTabList = p->pSrc;
+  for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
+    Table *pTab = pFrom->pTab;
+    assert( pTab!=0 );
+    if( (pTab->tabFlags & TF_Ephemeral)!=0 ){
+      /* A sub-query in the FROM clause of a SELECT */
+      Select *pSel = pFrom->pSelect;
+      if( pSel ){
+        while( pSel->pPrior ) pSel = pSel->pPrior;
+        sqlite3SelectAddColumnTypeAndCollation(pParse, pTab, pSel);
+      }
+    }
+  }
+}
+#endif
+
+
+/*
+** This routine adds datatype and collating sequence information to
+** the Table structures of all FROM-clause subqueries in a
+** SELECT statement.
+**
+** Use this routine after name resolution.
+*/
+static void sqlite3SelectAddTypeInfo(Parse *pParse, Select *pSelect){
+#ifndef SQLITE_OMIT_SUBQUERY
+  Walker w;
+  memset(&w, 0, sizeof(w));
+  w.xSelectCallback2 = selectAddSubqueryTypeInfo;
+  w.xExprCallback = sqlite3ExprWalkNoop;
+  w.pParse = pParse;
+  sqlite3WalkSelect(&w, pSelect);
+#endif
+}
+
+
+/*
+** This routine sets up a SELECT statement for processing.  The
+** following is accomplished:
+**
+**     *  VDBE Cursor numbers are assigned to all FROM-clause terms.
+**     *  Ephemeral Table objects are created for all FROM-clause subqueries.
+**     *  ON and USING clauses are shifted into WHERE statements
+**     *  Wildcards "*" and "TABLE.*" in result sets are expanded.
+**     *  Identifiers in expression are matched to tables.
+**
+** This routine acts recursively on all subqueries within the SELECT.
+*/
+SQLITE_PRIVATE void sqlite3SelectPrep(
+  Parse *pParse,         /* The parser context */
+  Select *p,             /* The SELECT statement being coded. */
+  NameContext *pOuterNC  /* Name context for container */
+){
+  sqlite3 *db;
+  if( NEVER(p==0) ) return;
+  db = pParse->db;
+  if( db->mallocFailed ) return;
+  if( p->selFlags & SF_HasTypeInfo ) return;
+  sqlite3SelectExpand(pParse, p);
+  if( pParse->nErr || db->mallocFailed ) return;
+  sqlite3ResolveSelectNames(pParse, p, pOuterNC);
+  if( pParse->nErr || db->mallocFailed ) return;
+  sqlite3SelectAddTypeInfo(pParse, p);
+}
+
+/*
+** Reset the aggregate accumulator.
+**
+** The aggregate accumulator is a set of memory cells that hold
+** intermediate results while calculating an aggregate.  This
+** routine generates code that stores NULLs in all of those memory
+** cells.
+*/
+static void resetAccumulator(Parse *pParse, AggInfo *pAggInfo){
+  Vdbe *v = pParse->pVdbe;
+  int i;
+  struct AggInfo_func *pFunc;
+  int nReg = pAggInfo->nFunc + pAggInfo->nColumn;
+  if( nReg==0 ) return;
+#ifdef SQLITE_DEBUG
+  /* Verify that all AggInfo registers are within the range specified by
+  ** AggInfo.mnReg..AggInfo.mxReg */
+  assert( nReg==pAggInfo->mxReg-pAggInfo->mnReg+1 );
+  for(i=0; i<pAggInfo->nColumn; i++){
+    assert( pAggInfo->aCol[i].iMem>=pAggInfo->mnReg
+         && pAggInfo->aCol[i].iMem<=pAggInfo->mxReg );
+  }
+  for(i=0; i<pAggInfo->nFunc; i++){
+    assert( pAggInfo->aFunc[i].iMem>=pAggInfo->mnReg
+         && pAggInfo->aFunc[i].iMem<=pAggInfo->mxReg );
+  }
+#endif
+  sqlite3VdbeAddOp3(v, OP_Null, 0, pAggInfo->mnReg, pAggInfo->mxReg);
+  for(pFunc=pAggInfo->aFunc, i=0; i<pAggInfo->nFunc; i++, pFunc++){
+    if( pFunc->iDistinct>=0 ){
+      Expr *pE = pFunc->pExpr;
+      assert( !ExprHasProperty(pE, EP_xIsSelect) );
+      if( pE->x.pList==0 || pE->x.pList->nExpr!=1 ){
+        sqlite3ErrorMsg(pParse, "DISTINCT aggregates must have exactly one "
+           "argument");
+        pFunc->iDistinct = -1;
+      }else{
+        KeyInfo *pKeyInfo = keyInfoFromExprList(pParse, pE->x.pList, 0, 0);
+        sqlite3VdbeAddOp4(v, OP_OpenEphemeral, pFunc->iDistinct, 0, 0,
+                          (char*)pKeyInfo, P4_KEYINFO);
+      }
+    }
+  }
+}
+
+/*
+** Invoke the OP_AggFinalize opcode for every aggregate function
+** in the AggInfo structure.
+*/
+static void finalizeAggFunctions(Parse *pParse, AggInfo *pAggInfo){
+  Vdbe *v = pParse->pVdbe;
+  int i;
+  struct AggInfo_func *pF;
+  for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
+    ExprList *pList = pF->pExpr->x.pList;
+    assert( !ExprHasProperty(pF->pExpr, EP_xIsSelect) );
+    sqlite3VdbeAddOp4(v, OP_AggFinal, pF->iMem, pList ? pList->nExpr : 0, 0,
+                      (void*)pF->pFunc, P4_FUNCDEF);
+  }
+}
+
+/*
+** Update the accumulator memory cells for an aggregate based on
+** the current cursor position.
+*/
+static void updateAccumulator(Parse *pParse, AggInfo *pAggInfo){
+  Vdbe *v = pParse->pVdbe;
+  int i;
+  int regHit = 0;
+  int addrHitTest = 0;
+  struct AggInfo_func *pF;
+  struct AggInfo_col *pC;
+
+  pAggInfo->directMode = 1;
+  for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
+    int nArg;
+    int addrNext = 0;
+    int regAgg;
+    ExprList *pList = pF->pExpr->x.pList;
+    assert( !ExprHasProperty(pF->pExpr, EP_xIsSelect) );
+    if( pList ){
+      nArg = pList->nExpr;
+      regAgg = sqlite3GetTempRange(pParse, nArg);
+      sqlite3ExprCodeExprList(pParse, pList, regAgg, 0, SQLITE_ECEL_DUP);
+    }else{
+      nArg = 0;
+      regAgg = 0;
+    }
+    if( pF->iDistinct>=0 ){
+      addrNext = sqlite3VdbeMakeLabel(v);
+      testcase( nArg==0 );  /* Error condition */
+      testcase( nArg>1 );   /* Also an error */
+      codeDistinct(pParse, pF->iDistinct, addrNext, 1, regAgg);
+    }
+    if( pF->pFunc->funcFlags & SQLITE_FUNC_NEEDCOLL ){
+      CollSeq *pColl = 0;
+      struct ExprList_item *pItem;
+      int j;
+      assert( pList!=0 );  /* pList!=0 if pF->pFunc has NEEDCOLL */
+      for(j=0, pItem=pList->a; !pColl && j<nArg; j++, pItem++){
+        pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
+      }
+      if( !pColl ){
+        pColl = pParse->db->pDfltColl;
+      }
+      if( regHit==0 && pAggInfo->nAccumulator ) regHit = ++pParse->nMem;
+      sqlite3VdbeAddOp4(v, OP_CollSeq, regHit, 0, 0, (char *)pColl, P4_COLLSEQ);
+    }
+    sqlite3VdbeAddOp4(v, OP_AggStep0, 0, regAgg, pF->iMem,
+                      (void*)pF->pFunc, P4_FUNCDEF);
+    sqlite3VdbeChangeP5(v, (u8)nArg);
+    sqlite3ExprCacheAffinityChange(pParse, regAgg, nArg);
+    sqlite3ReleaseTempRange(pParse, regAgg, nArg);
+    if( addrNext ){
+      sqlite3VdbeResolveLabel(v, addrNext);
+      sqlite3ExprCacheClear(pParse);
+    }
+  }
+
+  /* Before populating the accumulator registers, clear the column cache.
+  ** Otherwise, if any of the required column values are already present 
+  ** in registers, sqlite3ExprCode() may use OP_SCopy to copy the value
+  ** to pC->iMem. But by the time the value is used, the original register
+  ** may have been used, invalidating the underlying buffer holding the
+  ** text or blob value. See ticket [883034dcb5].
+  **
+  ** Another solution would be to change the OP_SCopy used to copy cached
+  ** values to an OP_Copy.
+  */
+  if( regHit ){
+    addrHitTest = sqlite3VdbeAddOp1(v, OP_If, regHit); VdbeCoverage(v);
+  }
+  sqlite3ExprCacheClear(pParse);
+  for(i=0, pC=pAggInfo->aCol; i<pAggInfo->nAccumulator; i++, pC++){
+    sqlite3ExprCode(pParse, pC->pExpr, pC->iMem);
+  }
+  pAggInfo->directMode = 0;
+  sqlite3ExprCacheClear(pParse);
+  if( addrHitTest ){
+    sqlite3VdbeJumpHere(v, addrHitTest);
+  }
+}
+
+/*
+** Add a single OP_Explain instruction to the VDBE to explain a simple
+** count(*) query ("SELECT count(*) FROM pTab").
+*/
+#ifndef SQLITE_OMIT_EXPLAIN
+static void explainSimpleCount(
+  Parse *pParse,                  /* Parse context */
+  Table *pTab,                    /* Table being queried */
+  Index *pIdx                     /* Index used to optimize scan, or NULL */
+){
+  if( pParse->explain==2 ){
+    int bCover = (pIdx!=0 && (HasRowid(pTab) || !IsPrimaryKeyIndex(pIdx)));
+    char *zEqp = sqlite3MPrintf(pParse->db, "SCAN TABLE %s%s%s",
+        pTab->zName,
+        bCover ? " USING COVERING INDEX " : "",
+        bCover ? pIdx->zName : ""
+    );
+    sqlite3VdbeAddOp4(
+        pParse->pVdbe, OP_Explain, pParse->iSelectId, 0, 0, zEqp, P4_DYNAMIC
+    );
+  }
+}
+#else
+# define explainSimpleCount(a,b,c)
+#endif
+
+/*
+** Generate code for the SELECT statement given in the p argument.  
+**
+** The results are returned according to the SelectDest structure.
+** See comments in sqliteInt.h for further information.
+**
+** This routine returns the number of errors.  If any errors are
+** encountered, then an appropriate error message is left in
+** pParse->zErrMsg.
+**
+** This routine does NOT free the Select structure passed in.  The
+** calling function needs to do that.
+*/
+SQLITE_PRIVATE int sqlite3Select(
+  Parse *pParse,         /* The parser context */
+  Select *p,             /* The SELECT statement being coded. */
+  SelectDest *pDest      /* What to do with the query results */
+){
+  int i, j;              /* Loop counters */
+  WhereInfo *pWInfo;     /* Return from sqlite3WhereBegin() */
+  Vdbe *v;               /* The virtual machine under construction */
+  int isAgg;             /* True for select lists like "count(*)" */
+  ExprList *pEList = 0;  /* List of columns to extract. */
+  SrcList *pTabList;     /* List of tables to select from */
+  Expr *pWhere;          /* The WHERE clause.  May be NULL */
+  ExprList *pGroupBy;    /* The GROUP BY clause.  May be NULL */
+  Expr *pHaving;         /* The HAVING clause.  May be NULL */
+  int rc = 1;            /* Value to return from this function */
+  DistinctCtx sDistinct; /* Info on how to code the DISTINCT keyword */
+  SortCtx sSort;         /* Info on how to code the ORDER BY clause */
+  AggInfo sAggInfo;      /* Information used by aggregate queries */
+  int iEnd;              /* Address of the end of the query */
+  sqlite3 *db;           /* The database connection */
+
+#ifndef SQLITE_OMIT_EXPLAIN
+  int iRestoreSelectId = pParse->iSelectId;
+  pParse->iSelectId = pParse->iNextSelectId++;
+#endif
+
+  db = pParse->db;
+  if( p==0 || db->mallocFailed || pParse->nErr ){
+    return 1;
+  }
+  if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1;
+  memset(&sAggInfo, 0, sizeof(sAggInfo));
+#if SELECTTRACE_ENABLED
+  pParse->nSelectIndent++;
+  SELECTTRACE(1,pParse,p, ("begin processing:\n"));
+  if( sqlite3SelectTrace & 0x100 ){
+    sqlite3TreeViewSelect(0, p, 0);
+  }
+#endif
+
+  assert( p->pOrderBy==0 || pDest->eDest!=SRT_DistFifo );
+  assert( p->pOrderBy==0 || pDest->eDest!=SRT_Fifo );
+  assert( p->pOrderBy==0 || pDest->eDest!=SRT_DistQueue );
+  assert( p->pOrderBy==0 || pDest->eDest!=SRT_Queue );
+  if( IgnorableOrderby(pDest) ){
+    assert(pDest->eDest==SRT_Exists || pDest->eDest==SRT_Union || 
+           pDest->eDest==SRT_Except || pDest->eDest==SRT_Discard ||
+           pDest->eDest==SRT_Queue  || pDest->eDest==SRT_DistFifo ||
+           pDest->eDest==SRT_DistQueue || pDest->eDest==SRT_Fifo);
+    /* If ORDER BY makes no difference in the output then neither does
+    ** DISTINCT so it can be removed too. */
+    sqlite3ExprListDelete(db, p->pOrderBy);
+    p->pOrderBy = 0;
+    p->selFlags &= ~SF_Distinct;
+  }
+  sqlite3SelectPrep(pParse, p, 0);
+  memset(&sSort, 0, sizeof(sSort));
+  sSort.pOrderBy = p->pOrderBy;
+  pTabList = p->pSrc;
+  if( pParse->nErr || db->mallocFailed ){
+    goto select_end;
+  }
+  assert( p->pEList!=0 );
+  isAgg = (p->selFlags & SF_Aggregate)!=0;
+#if SELECTTRACE_ENABLED
+  if( sqlite3SelectTrace & 0x100 ){
+    SELECTTRACE(0x100,pParse,p, ("after name resolution:\n"));
+    sqlite3TreeViewSelect(0, p, 0);
+  }
+#endif
+
+  /* Try to flatten subqueries in the FROM clause up into the main query
+  */
+#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
+  for(i=0; !p->pPrior && i<pTabList->nSrc; i++){
+    struct SrcList_item *pItem = &pTabList->a[i];
+    Select *pSub = pItem->pSelect;
+    int isAggSub;
+    Table *pTab = pItem->pTab;
+    if( pSub==0 ) continue;
+
+    /* Catch mismatch in the declared columns of a view and the number of
+    ** columns in the SELECT on the RHS */
+    if( pTab->nCol!=pSub->pEList->nExpr ){
+      sqlite3ErrorMsg(pParse, "expected %d columns for '%s' but got %d",
+                      pTab->nCol, pTab->zName, pSub->pEList->nExpr);
+      goto select_end;
+    }
+
+    isAggSub = (pSub->selFlags & SF_Aggregate)!=0;
+    if( flattenSubquery(pParse, p, i, isAgg, isAggSub) ){
+      /* This subquery can be absorbed into its parent. */
+      if( isAggSub ){
+        isAgg = 1;
+        p->selFlags |= SF_Aggregate;
+      }
+      i = -1;
+    }
+    pTabList = p->pSrc;
+    if( db->mallocFailed ) goto select_end;
+    if( !IgnorableOrderby(pDest) ){
+      sSort.pOrderBy = p->pOrderBy;
+    }
+  }
+#endif
+
+  /* Get a pointer the VDBE under construction, allocating a new VDBE if one
+  ** does not already exist */
+  v = sqlite3GetVdbe(pParse);
+  if( v==0 ) goto select_end;
+
+#ifndef SQLITE_OMIT_COMPOUND_SELECT
+  /* Handle compound SELECT statements using the separate multiSelect()
+  ** procedure.
+  */
+  if( p->pPrior ){
+    rc = multiSelect(pParse, p, pDest);
+    explainSetInteger(pParse->iSelectId, iRestoreSelectId);
+#if SELECTTRACE_ENABLED
+    SELECTTRACE(1,pParse,p,("end compound-select processing\n"));
+    pParse->nSelectIndent--;
+#endif
+    return rc;
+  }
+#endif
+
+  /* Generate code for all sub-queries in the FROM clause
+  */
+#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
+  for(i=0; i<pTabList->nSrc; i++){
+    struct SrcList_item *pItem = &pTabList->a[i];
+    SelectDest dest;
+    Select *pSub = pItem->pSelect;
+    if( pSub==0 ) continue;
+
+    /* Sometimes the code for a subquery will be generated more than
+    ** once, if the subquery is part of the WHERE clause in a LEFT JOIN,
+    ** for example.  In that case, do not regenerate the code to manifest
+    ** a view or the co-routine to implement a view.  The first instance
+    ** is sufficient, though the subroutine to manifest the view does need
+    ** to be invoked again. */
+    if( pItem->addrFillSub ){
+      if( pItem->fg.viaCoroutine==0 ){
+        sqlite3VdbeAddOp2(v, OP_Gosub, pItem->regReturn, pItem->addrFillSub);
+      }
+      continue;
+    }
+
+    /* Increment Parse.nHeight by the height of the largest expression
+    ** tree referred to by this, the parent select. The child select
+    ** may contain expression trees of at most
+    ** (SQLITE_MAX_EXPR_DEPTH-Parse.nHeight) height. This is a bit
+    ** more conservative than necessary, but much easier than enforcing
+    ** an exact limit.
+    */
+    pParse->nHeight += sqlite3SelectExprHeight(p);
+
+    /* Make copies of constant WHERE-clause terms in the outer query down
+    ** inside the subquery.  This can help the subquery to run more efficiently.
+    */
+    if( (pItem->fg.jointype & JT_OUTER)==0
+     && pushDownWhereTerms(db, pSub, p->pWhere, pItem->iCursor)
+    ){
+#if SELECTTRACE_ENABLED
+      if( sqlite3SelectTrace & 0x100 ){
+        SELECTTRACE(0x100,pParse,p,("After WHERE-clause push-down:\n"));
+        sqlite3TreeViewSelect(0, p, 0);
+      }
+#endif
+    }
+
+    /* Generate code to implement the subquery
+    **
+    ** The subquery is implemented as a co-routine if all of these are true:
+    **   (1)  The subquery is guaranteed to be the outer loop (so that it
+    **        does not need to be computed more than once)
+    **   (2)  The ALL keyword after SELECT is omitted.  (Applications are
+    **        allowed to say "SELECT ALL" instead of just "SELECT" to disable
+    **        the use of co-routines.)
+    **   (3)  Co-routines are not disabled using sqlite3_test_control()
+    **        with SQLITE_TESTCTRL_OPTIMIZATIONS.
+    **
+    ** TODO: Are there other reasons beside (1) to use a co-routine
+    ** implementation?
+    */
+    if( i==0
+     && (pTabList->nSrc==1
+            || (pTabList->a[1].fg.jointype&(JT_LEFT|JT_CROSS))!=0)  /* (1) */
+     && (p->selFlags & SF_All)==0                                   /* (2) */
+     && OptimizationEnabled(db, SQLITE_SubqCoroutine)               /* (3) */
+    ){
+      /* Implement a co-routine that will return a single row of the result
+      ** set on each invocation.
+      */
+      int addrTop = sqlite3VdbeCurrentAddr(v)+1;
+      pItem->regReturn = ++pParse->nMem;
+      sqlite3VdbeAddOp3(v, OP_InitCoroutine, pItem->regReturn, 0, addrTop);
+      VdbeComment((v, "%s", pItem->pTab->zName));
+      pItem->addrFillSub = addrTop;
+      sqlite3SelectDestInit(&dest, SRT_Coroutine, pItem->regReturn);
+      explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId);
+      sqlite3Select(pParse, pSub, &dest);
+      pItem->pTab->nRowLogEst = pSub->nSelectRow;
+      pItem->fg.viaCoroutine = 1;
+      pItem->regResult = dest.iSdst;
+      sqlite3VdbeEndCoroutine(v, pItem->regReturn);
+      sqlite3VdbeJumpHere(v, addrTop-1);
+      sqlite3ClearTempRegCache(pParse);
+    }else{
+      /* Generate a subroutine that will fill an ephemeral table with
+      ** the content of this subquery.  pItem->addrFillSub will point
+      ** to the address of the generated subroutine.  pItem->regReturn
+      ** is a register allocated to hold the subroutine return address
+      */
+      int topAddr;
+      int onceAddr = 0;
+      int retAddr;
+      assert( pItem->addrFillSub==0 );
+      pItem->regReturn = ++pParse->nMem;
+      topAddr = sqlite3VdbeAddOp2(v, OP_Integer, 0, pItem->regReturn);
+      pItem->addrFillSub = topAddr+1;
+      if( pItem->fg.isCorrelated==0 ){
+        /* If the subquery is not correlated and if we are not inside of
+        ** a trigger, then we only need to compute the value of the subquery
+        ** once. */
+        onceAddr = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
+        VdbeComment((v, "materialize \"%s\"", pItem->pTab->zName));
+      }else{
+        VdbeNoopComment((v, "materialize \"%s\"", pItem->pTab->zName));
+      }
+      sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor);
+      explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId);
+      sqlite3Select(pParse, pSub, &dest);
+      pItem->pTab->nRowLogEst = pSub->nSelectRow;
+      if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr);
+      retAddr = sqlite3VdbeAddOp1(v, OP_Return, pItem->regReturn);
+      VdbeComment((v, "end %s", pItem->pTab->zName));
+      sqlite3VdbeChangeP1(v, topAddr, retAddr);
+      sqlite3ClearTempRegCache(pParse);
+    }
+    if( db->mallocFailed ) goto select_end;
+    pParse->nHeight -= sqlite3SelectExprHeight(p);
+  }
+#endif
+
+  /* Various elements of the SELECT copied into local variables for
+  ** convenience */
+  pEList = p->pEList;
+  pWhere = p->pWhere;
+  pGroupBy = p->pGroupBy;
+  pHaving = p->pHaving;
+  sDistinct.isTnct = (p->selFlags & SF_Distinct)!=0;
+
+#if SELECTTRACE_ENABLED
+  if( sqlite3SelectTrace & 0x400 ){
+    SELECTTRACE(0x400,pParse,p,("After all FROM-clause analysis:\n"));
+    sqlite3TreeViewSelect(0, p, 0);
+  }
+#endif
+
+  /* If the query is DISTINCT with an ORDER BY but is not an aggregate, and 
+  ** if the select-list is the same as the ORDER BY list, then this query
+  ** can be rewritten as a GROUP BY. In other words, this:
+  **
+  **     SELECT DISTINCT xyz FROM ... ORDER BY xyz
+  **
+  ** is transformed to:
+  **
+  **     SELECT xyz FROM ... GROUP BY xyz ORDER BY xyz
+  **
+  ** The second form is preferred as a single index (or temp-table) may be 
+  ** used for both the ORDER BY and DISTINCT processing. As originally 
+  ** written the query must use a temp-table for at least one of the ORDER 
+  ** BY and DISTINCT, and an index or separate temp-table for the other.
+  */
+  if( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct 
+   && sqlite3ExprListCompare(sSort.pOrderBy, pEList, -1)==0
+  ){
+    p->selFlags &= ~SF_Distinct;
+    pGroupBy = p->pGroupBy = sqlite3ExprListDup(db, pEList, 0);
+    /* Notice that even thought SF_Distinct has been cleared from p->selFlags,
+    ** the sDistinct.isTnct is still set.  Hence, isTnct represents the
+    ** original setting of the SF_Distinct flag, not the current setting */
+    assert( sDistinct.isTnct );
+
+#if SELECTTRACE_ENABLED
+    if( sqlite3SelectTrace & 0x400 ){
+      SELECTTRACE(0x400,pParse,p,("Transform DISTINCT into GROUP BY:\n"));
+      sqlite3TreeViewSelect(0, p, 0);
+    }
+#endif
+  }
+
+  /* If there is an ORDER BY clause, then create an ephemeral index to
+  ** do the sorting.  But this sorting ephemeral index might end up
+  ** being unused if the data can be extracted in pre-sorted order.
+  ** If that is the case, then the OP_OpenEphemeral instruction will be
+  ** changed to an OP_Noop once we figure out that the sorting index is
+  ** not needed.  The sSort.addrSortIndex variable is used to facilitate
+  ** that change.
+  */
+  if( sSort.pOrderBy ){
+    KeyInfo *pKeyInfo;
+    pKeyInfo = keyInfoFromExprList(pParse, sSort.pOrderBy, 0, pEList->nExpr);
+    sSort.iECursor = pParse->nTab++;
+    sSort.addrSortIndex =
+      sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
+          sSort.iECursor, sSort.pOrderBy->nExpr+1+pEList->nExpr, 0,
+          (char*)pKeyInfo, P4_KEYINFO
+      );
+  }else{
+    sSort.addrSortIndex = -1;
+  }
+
+  /* If the output is destined for a temporary table, open that table.
+  */
+  if( pDest->eDest==SRT_EphemTab ){
+    sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pDest->iSDParm, pEList->nExpr);
+  }
+
+  /* Set the limiter.
+  */
+  iEnd = sqlite3VdbeMakeLabel(v);
+  p->nSelectRow = 320;  /* 4 billion rows */
+  computeLimitRegisters(pParse, p, iEnd);
+  if( p->iLimit==0 && sSort.addrSortIndex>=0 ){
+    sqlite3VdbeChangeOpcode(v, sSort.addrSortIndex, OP_SorterOpen);
+    sSort.sortFlags |= SORTFLAG_UseSorter;
+  }
+
+  /* Open an ephemeral index to use for the distinct set.
+  */
+  if( p->selFlags & SF_Distinct ){
+    sDistinct.tabTnct = pParse->nTab++;
+    sDistinct.addrTnct = sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
+                             sDistinct.tabTnct, 0, 0,
+                             (char*)keyInfoFromExprList(pParse, p->pEList,0,0),
+                             P4_KEYINFO);
+    sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
+    sDistinct.eTnctType = WHERE_DISTINCT_UNORDERED;
+  }else{
+    sDistinct.eTnctType = WHERE_DISTINCT_NOOP;
+  }
+
+  if( !isAgg && pGroupBy==0 ){
+    /* No aggregate functions and no GROUP BY clause */
+    u16 wctrlFlags = (sDistinct.isTnct ? WHERE_WANT_DISTINCT : 0);
+    assert( WHERE_USE_LIMIT==SF_FixedLimit );
+    wctrlFlags |= p->selFlags & SF_FixedLimit;
+
+    /* Begin the database scan. */
+    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, sSort.pOrderBy,
+                               p->pEList, wctrlFlags, p->nSelectRow);
+    if( pWInfo==0 ) goto select_end;
+    if( sqlite3WhereOutputRowCount(pWInfo) < p->nSelectRow ){
+      p->nSelectRow = sqlite3WhereOutputRowCount(pWInfo);
+    }
+    if( sDistinct.isTnct && sqlite3WhereIsDistinct(pWInfo) ){
+      sDistinct.eTnctType = sqlite3WhereIsDistinct(pWInfo);
+    }
+    if( sSort.pOrderBy ){
+      sSort.nOBSat = sqlite3WhereIsOrdered(pWInfo);
+      sSort.bOrderedInnerLoop = sqlite3WhereOrderedInnerLoop(pWInfo);
+      if( sSort.nOBSat==sSort.pOrderBy->nExpr ){
+        sSort.pOrderBy = 0;
+      }
+    }
+
+    /* If sorting index that was created by a prior OP_OpenEphemeral 
+    ** instruction ended up not being needed, then change the OP_OpenEphemeral
+    ** into an OP_Noop.
+    */
+    if( sSort.addrSortIndex>=0 && sSort.pOrderBy==0 ){
+      sqlite3VdbeChangeToNoop(v, sSort.addrSortIndex);
+    }
+
+    /* Use the standard inner loop. */
+    selectInnerLoop(pParse, p, pEList, -1, &sSort, &sDistinct, pDest,
+                    sqlite3WhereContinueLabel(pWInfo),
+                    sqlite3WhereBreakLabel(pWInfo));
+
+    /* End the database scan loop.
+    */
+    sqlite3WhereEnd(pWInfo);
+  }else{
+    /* This case when there exist aggregate functions or a GROUP BY clause
+    ** or both */
+    NameContext sNC;    /* Name context for processing aggregate information */
+    int iAMem;          /* First Mem address for storing current GROUP BY */
+    int iBMem;          /* First Mem address for previous GROUP BY */
+    int iUseFlag;       /* Mem address holding flag indicating that at least
+                        ** one row of the input to the aggregator has been
+                        ** processed */
+    int iAbortFlag;     /* Mem address which causes query abort if positive */
+    int groupBySort;    /* Rows come from source in GROUP BY order */
+    int addrEnd;        /* End of processing for this SELECT */
+    int sortPTab = 0;   /* Pseudotable used to decode sorting results */
+    int sortOut = 0;    /* Output register from the sorter */
+    int orderByGrp = 0; /* True if the GROUP BY and ORDER BY are the same */
+
+    /* Remove any and all aliases between the result set and the
+    ** GROUP BY clause.
+    */
+    if( pGroupBy ){
+      int k;                        /* Loop counter */
+      struct ExprList_item *pItem;  /* For looping over expression in a list */
+
+      for(k=p->pEList->nExpr, pItem=p->pEList->a; k>0; k--, pItem++){
+        pItem->u.x.iAlias = 0;
+      }
+      for(k=pGroupBy->nExpr, pItem=pGroupBy->a; k>0; k--, pItem++){
+        pItem->u.x.iAlias = 0;
+      }
+      assert( 66==sqlite3LogEst(100) );
+      if( p->nSelectRow>66 ) p->nSelectRow = 66;
+    }else{
+      assert( 0==sqlite3LogEst(1) );
+      p->nSelectRow = 0;
+    }
+
+    /* If there is both a GROUP BY and an ORDER BY clause and they are
+    ** identical, then it may be possible to disable the ORDER BY clause 
+    ** on the grounds that the GROUP BY will cause elements to come out 
+    ** in the correct order. It also may not - the GROUP BY might use a
+    ** database index that causes rows to be grouped together as required
+    ** but not actually sorted. Either way, record the fact that the
+    ** ORDER BY and GROUP BY clauses are the same by setting the orderByGrp
+    ** variable.  */
+    if( sqlite3ExprListCompare(pGroupBy, sSort.pOrderBy, -1)==0 ){
+      orderByGrp = 1;
+    }
+ 
+    /* Create a label to jump to when we want to abort the query */
+    addrEnd = sqlite3VdbeMakeLabel(v);
+
+    /* Convert TK_COLUMN nodes into TK_AGG_COLUMN and make entries in
+    ** sAggInfo for all TK_AGG_FUNCTION nodes in expressions of the
+    ** SELECT statement.
+    */
+    memset(&sNC, 0, sizeof(sNC));
+    sNC.pParse = pParse;
+    sNC.pSrcList = pTabList;
+    sNC.pAggInfo = &sAggInfo;
+    sAggInfo.mnReg = pParse->nMem+1;
+    sAggInfo.nSortingColumn = pGroupBy ? pGroupBy->nExpr : 0;
+    sAggInfo.pGroupBy = pGroupBy;
+    sqlite3ExprAnalyzeAggList(&sNC, pEList);
+    sqlite3ExprAnalyzeAggList(&sNC, sSort.pOrderBy);
+    if( pHaving ){
+      sqlite3ExprAnalyzeAggregates(&sNC, pHaving);
+    }
+    sAggInfo.nAccumulator = sAggInfo.nColumn;
+    for(i=0; i<sAggInfo.nFunc; i++){
+      assert( !ExprHasProperty(sAggInfo.aFunc[i].pExpr, EP_xIsSelect) );
+      sNC.ncFlags |= NC_InAggFunc;
+      sqlite3ExprAnalyzeAggList(&sNC, sAggInfo.aFunc[i].pExpr->x.pList);
+      sNC.ncFlags &= ~NC_InAggFunc;
+    }
+    sAggInfo.mxReg = pParse->nMem;
+    if( db->mallocFailed ) goto select_end;
+
+    /* Processing for aggregates with GROUP BY is very different and
+    ** much more complex than aggregates without a GROUP BY.
+    */
+    if( pGroupBy ){
+      KeyInfo *pKeyInfo;  /* Keying information for the group by clause */
+      int addr1;          /* A-vs-B comparision jump */
+      int addrOutputRow;  /* Start of subroutine that outputs a result row */
+      int regOutputRow;   /* Return address register for output subroutine */
+      int addrSetAbort;   /* Set the abort flag and return */
+      int addrTopOfLoop;  /* Top of the input loop */
+      int addrSortingIdx; /* The OP_OpenEphemeral for the sorting index */
+      int addrReset;      /* Subroutine for resetting the accumulator */
+      int regReset;       /* Return address register for reset subroutine */
+
+      /* If there is a GROUP BY clause we might need a sorting index to
+      ** implement it.  Allocate that sorting index now.  If it turns out
+      ** that we do not need it after all, the OP_SorterOpen instruction
+      ** will be converted into a Noop.  
+      */
+      sAggInfo.sortingIdx = pParse->nTab++;
+      pKeyInfo = keyInfoFromExprList(pParse, pGroupBy, 0, sAggInfo.nColumn);
+      addrSortingIdx = sqlite3VdbeAddOp4(v, OP_SorterOpen, 
+          sAggInfo.sortingIdx, sAggInfo.nSortingColumn, 
+          0, (char*)pKeyInfo, P4_KEYINFO);
+
+      /* Initialize memory locations used by GROUP BY aggregate processing
+      */
+      iUseFlag = ++pParse->nMem;
+      iAbortFlag = ++pParse->nMem;
+      regOutputRow = ++pParse->nMem;
+      addrOutputRow = sqlite3VdbeMakeLabel(v);
+      regReset = ++pParse->nMem;
+      addrReset = sqlite3VdbeMakeLabel(v);
+      iAMem = pParse->nMem + 1;
+      pParse->nMem += pGroupBy->nExpr;
+      iBMem = pParse->nMem + 1;
+      pParse->nMem += pGroupBy->nExpr;
+      sqlite3VdbeAddOp2(v, OP_Integer, 0, iAbortFlag);
+      VdbeComment((v, "clear abort flag"));
+      sqlite3VdbeAddOp2(v, OP_Integer, 0, iUseFlag);
+      VdbeComment((v, "indicate accumulator empty"));
+      sqlite3VdbeAddOp3(v, OP_Null, 0, iAMem, iAMem+pGroupBy->nExpr-1);
+
+      /* Begin a loop that will extract all source rows in GROUP BY order.
+      ** This might involve two separate loops with an OP_Sort in between, or
+      ** it might be a single loop that uses an index to extract information
+      ** in the right order to begin with.
+      */
+      sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
+      pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pGroupBy, 0,
+          WHERE_GROUPBY | (orderByGrp ? WHERE_SORTBYGROUP : 0), 0
+      );
+      if( pWInfo==0 ) goto select_end;
+      if( sqlite3WhereIsOrdered(pWInfo)==pGroupBy->nExpr ){
+        /* The optimizer is able to deliver rows in group by order so
+        ** we do not have to sort.  The OP_OpenEphemeral table will be
+        ** cancelled later because we still need to use the pKeyInfo
+        */
+        groupBySort = 0;
+      }else{
+        /* Rows are coming out in undetermined order.  We have to push
+        ** each row into a sorting index, terminate the first loop,
+        ** then loop over the sorting index in order to get the output
+        ** in sorted order
+        */
+        int regBase;
+        int regRecord;
+        int nCol;
+        int nGroupBy;
+
+        explainTempTable(pParse, 
+            (sDistinct.isTnct && (p->selFlags&SF_Distinct)==0) ?
+                    "DISTINCT" : "GROUP BY");
+
+        groupBySort = 1;
+        nGroupBy = pGroupBy->nExpr;
+        nCol = nGroupBy;
+        j = nGroupBy;
+        for(i=0; i<sAggInfo.nColumn; i++){
+          if( sAggInfo.aCol[i].iSorterColumn>=j ){
+            nCol++;
+            j++;
+          }
+        }
+        regBase = sqlite3GetTempRange(pParse, nCol);
+        sqlite3ExprCacheClear(pParse);
+        sqlite3ExprCodeExprList(pParse, pGroupBy, regBase, 0, 0);
+        j = nGroupBy;
+        for(i=0; i<sAggInfo.nColumn; i++){
+          struct AggInfo_col *pCol = &sAggInfo.aCol[i];
+          if( pCol->iSorterColumn>=j ){
+            int r1 = j + regBase;
+            sqlite3ExprCodeGetColumnToReg(pParse, 
+                               pCol->pTab, pCol->iColumn, pCol->iTable, r1);
+            j++;
+          }
+        }
+        regRecord = sqlite3GetTempReg(pParse);
+        sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol, regRecord);
+        sqlite3VdbeAddOp2(v, OP_SorterInsert, sAggInfo.sortingIdx, regRecord);
+        sqlite3ReleaseTempReg(pParse, regRecord);
+        sqlite3ReleaseTempRange(pParse, regBase, nCol);
+        sqlite3WhereEnd(pWInfo);
+        sAggInfo.sortingIdxPTab = sortPTab = pParse->nTab++;
+        sortOut = sqlite3GetTempReg(pParse);
+        sqlite3VdbeAddOp3(v, OP_OpenPseudo, sortPTab, sortOut, nCol);
+        sqlite3VdbeAddOp2(v, OP_SorterSort, sAggInfo.sortingIdx, addrEnd);
+        VdbeComment((v, "GROUP BY sort")); VdbeCoverage(v);
+        sAggInfo.useSortingIdx = 1;
+        sqlite3ExprCacheClear(pParse);
+
+      }
+
+      /* If the index or temporary table used by the GROUP BY sort
+      ** will naturally deliver rows in the order required by the ORDER BY
+      ** clause, cancel the ephemeral table open coded earlier.
+      **
+      ** This is an optimization - the correct answer should result regardless.
+      ** Use the SQLITE_GroupByOrder flag with SQLITE_TESTCTRL_OPTIMIZER to 
+      ** disable this optimization for testing purposes.  */
+      if( orderByGrp && OptimizationEnabled(db, SQLITE_GroupByOrder) 
+       && (groupBySort || sqlite3WhereIsSorted(pWInfo))
+      ){
+        sSort.pOrderBy = 0;
+        sqlite3VdbeChangeToNoop(v, sSort.addrSortIndex);
+      }
+
+      /* Evaluate the current GROUP BY terms and store in b0, b1, b2...
+      ** (b0 is memory location iBMem+0, b1 is iBMem+1, and so forth)
+      ** Then compare the current GROUP BY terms against the GROUP BY terms
+      ** from the previous row currently stored in a0, a1, a2...
+      */
+      addrTopOfLoop = sqlite3VdbeCurrentAddr(v);
+      sqlite3ExprCacheClear(pParse);
+      if( groupBySort ){
+        sqlite3VdbeAddOp3(v, OP_SorterData, sAggInfo.sortingIdx,
+                          sortOut, sortPTab);
+      }
+      for(j=0; j<pGroupBy->nExpr; j++){
+        if( groupBySort ){
+          sqlite3VdbeAddOp3(v, OP_Column, sortPTab, j, iBMem+j);
+        }else{
+          sAggInfo.directMode = 1;
+          sqlite3ExprCode(pParse, pGroupBy->a[j].pExpr, iBMem+j);
+        }
+      }
+      sqlite3VdbeAddOp4(v, OP_Compare, iAMem, iBMem, pGroupBy->nExpr,
+                          (char*)sqlite3KeyInfoRef(pKeyInfo), P4_KEYINFO);
+      addr1 = sqlite3VdbeCurrentAddr(v);
+      sqlite3VdbeAddOp3(v, OP_Jump, addr1+1, 0, addr1+1); VdbeCoverage(v);
+
+      /* Generate code that runs whenever the GROUP BY changes.
+      ** Changes in the GROUP BY are detected by the previous code
+      ** block.  If there were no changes, this block is skipped.
+      **
+      ** This code copies current group by terms in b0,b1,b2,...
+      ** over to a0,a1,a2.  It then calls the output subroutine
+      ** and resets the aggregate accumulator registers in preparation
+      ** for the next GROUP BY batch.
+      */
+      sqlite3ExprCodeMove(pParse, iBMem, iAMem, pGroupBy->nExpr);
+      sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow);
+      VdbeComment((v, "output one row"));
+      sqlite3VdbeAddOp2(v, OP_IfPos, iAbortFlag, addrEnd); VdbeCoverage(v);
+      VdbeComment((v, "check abort flag"));
+      sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
+      VdbeComment((v, "reset accumulator"));
+
+      /* Update the aggregate accumulators based on the content of
+      ** the current row
+      */
+      sqlite3VdbeJumpHere(v, addr1);
+      updateAccumulator(pParse, &sAggInfo);
+      sqlite3VdbeAddOp2(v, OP_Integer, 1, iUseFlag);
+      VdbeComment((v, "indicate data in accumulator"));
+
+      /* End of the loop
+      */
+      if( groupBySort ){
+        sqlite3VdbeAddOp2(v, OP_SorterNext, sAggInfo.sortingIdx, addrTopOfLoop);
+        VdbeCoverage(v);
+      }else{
+        sqlite3WhereEnd(pWInfo);
+        sqlite3VdbeChangeToNoop(v, addrSortingIdx);
+      }
+
+      /* Output the final row of result
+      */
+      sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow);
+      VdbeComment((v, "output final row"));
+
+      /* Jump over the subroutines
+      */
+      sqlite3VdbeGoto(v, addrEnd);
+
+      /* Generate a subroutine that outputs a single row of the result
+      ** set.  This subroutine first looks at the iUseFlag.  If iUseFlag
+      ** is less than or equal to zero, the subroutine is a no-op.  If
+      ** the processing calls for the query to abort, this subroutine
+      ** increments the iAbortFlag memory location before returning in
+      ** order to signal the caller to abort.
+      */
+      addrSetAbort = sqlite3VdbeCurrentAddr(v);
+      sqlite3VdbeAddOp2(v, OP_Integer, 1, iAbortFlag);
+      VdbeComment((v, "set abort flag"));
+      sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
+      sqlite3VdbeResolveLabel(v, addrOutputRow);
+      addrOutputRow = sqlite3VdbeCurrentAddr(v);
+      sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2);
+      VdbeCoverage(v);
+      VdbeComment((v, "Groupby result generator entry point"));
+      sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
+      finalizeAggFunctions(pParse, &sAggInfo);
+      sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL);
+      selectInnerLoop(pParse, p, p->pEList, -1, &sSort,
+                      &sDistinct, pDest,
+                      addrOutputRow+1, addrSetAbort);
+      sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
+      VdbeComment((v, "end groupby result generator"));
+
+      /* Generate a subroutine that will reset the group-by accumulator
+      */
+      sqlite3VdbeResolveLabel(v, addrReset);
+      resetAccumulator(pParse, &sAggInfo);
+      sqlite3VdbeAddOp1(v, OP_Return, regReset);
+     
+    } /* endif pGroupBy.  Begin aggregate queries without GROUP BY: */
+    else {
+      ExprList *pDel = 0;
+#ifndef SQLITE_OMIT_BTREECOUNT
+      Table *pTab;
+      if( (pTab = isSimpleCount(p, &sAggInfo))!=0 ){
+        /* If isSimpleCount() returns a pointer to a Table structure, then
+        ** the SQL statement is of the form:
+        **
+        **   SELECT count(*) FROM <tbl>
+        **
+        ** where the Table structure returned represents table <tbl>.
+        **
+        ** This statement is so common that it is optimized specially. The
+        ** OP_Count instruction is executed either on the intkey table that
+        ** contains the data for table <tbl> or on one of its indexes. It
+        ** is better to execute the op on an index, as indexes are almost
+        ** always spread across less pages than their corresponding tables.
+        */
+        const int iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
+        const int iCsr = pParse->nTab++;     /* Cursor to scan b-tree */
+        Index *pIdx;                         /* Iterator variable */
+        KeyInfo *pKeyInfo = 0;               /* Keyinfo for scanned index */
+        Index *pBest = 0;                    /* Best index found so far */
+        int iRoot = pTab->tnum;              /* Root page of scanned b-tree */
+
+        sqlite3CodeVerifySchema(pParse, iDb);
+        sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
+
+        /* Search for the index that has the lowest scan cost.
+        **
+        ** (2011-04-15) Do not do a full scan of an unordered index.
+        **
+        ** (2013-10-03) Do not count the entries in a partial index.
+        **
+        ** In practice the KeyInfo structure will not be used. It is only 
+        ** passed to keep OP_OpenRead happy.
+        */
+        if( !HasRowid(pTab) ) pBest = sqlite3PrimaryKeyIndex(pTab);
+        for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+          if( pIdx->bUnordered==0
+           && pIdx->szIdxRow<pTab->szTabRow
+           && pIdx->pPartIdxWhere==0
+           && (!pBest || pIdx->szIdxRow<pBest->szIdxRow)
+          ){
+            pBest = pIdx;
+          }
+        }
+        if( pBest ){
+          iRoot = pBest->tnum;
+          pKeyInfo = sqlite3KeyInfoOfIndex(pParse, pBest);
+        }
+
+        /* Open a read-only cursor, execute the OP_Count, close the cursor. */
+        sqlite3VdbeAddOp4Int(v, OP_OpenRead, iCsr, iRoot, iDb, 1);
+        if( pKeyInfo ){
+          sqlite3VdbeChangeP4(v, -1, (char *)pKeyInfo, P4_KEYINFO);
+        }
+        sqlite3VdbeAddOp2(v, OP_Count, iCsr, sAggInfo.aFunc[0].iMem);
+        sqlite3VdbeAddOp1(v, OP_Close, iCsr);
+        explainSimpleCount(pParse, pTab, pBest);
+      }else
+#endif /* SQLITE_OMIT_BTREECOUNT */
+      {
+        /* Check if the query is of one of the following forms:
+        **
+        **   SELECT min(x) FROM ...
+        **   SELECT max(x) FROM ...
+        **
+        ** If it is, then ask the code in where.c to attempt to sort results
+        ** as if there was an "ORDER ON x" or "ORDER ON x DESC" clause. 
+        ** If where.c is able to produce results sorted in this order, then
+        ** add vdbe code to break out of the processing loop after the 
+        ** first iteration (since the first iteration of the loop is 
+        ** guaranteed to operate on the row with the minimum or maximum 
+        ** value of x, the only row required).
+        **
+        ** A special flag must be passed to sqlite3WhereBegin() to slightly
+        ** modify behavior as follows:
+        **
+        **   + If the query is a "SELECT min(x)", then the loop coded by
+        **     where.c should not iterate over any values with a NULL value
+        **     for x.
+        **
+        **   + The optimizer code in where.c (the thing that decides which
+        **     index or indices to use) should place a different priority on 
+        **     satisfying the 'ORDER BY' clause than it does in other cases.
+        **     Refer to code and comments in where.c for details.
+        */
+        ExprList *pMinMax = 0;
+        u8 flag = WHERE_ORDERBY_NORMAL;
+        
+        assert( p->pGroupBy==0 );
+        assert( flag==0 );
+        if( p->pHaving==0 ){
+          flag = minMaxQuery(&sAggInfo, &pMinMax);
+        }
+        assert( flag==0 || (pMinMax!=0 && pMinMax->nExpr==1) );
+
+        if( flag ){
+          pMinMax = sqlite3ExprListDup(db, pMinMax, 0);
+          pDel = pMinMax;
+          assert( db->mallocFailed || pMinMax!=0 );
+          if( !db->mallocFailed ){
+            pMinMax->a[0].sortOrder = flag!=WHERE_ORDERBY_MIN ?1:0;
+            pMinMax->a[0].pExpr->op = TK_COLUMN;
+          }
+        }
+  
+        /* This case runs if the aggregate has no GROUP BY clause.  The
+        ** processing is much simpler since there is only a single row
+        ** of output.
+        */
+        resetAccumulator(pParse, &sAggInfo);
+        pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pMinMax,0,flag,0);
+        if( pWInfo==0 ){
+          sqlite3ExprListDelete(db, pDel);
+          goto select_end;
+        }
+        updateAccumulator(pParse, &sAggInfo);
+        assert( pMinMax==0 || pMinMax->nExpr==1 );
+        if( sqlite3WhereIsOrdered(pWInfo)>0 ){
+          sqlite3VdbeGoto(v, sqlite3WhereBreakLabel(pWInfo));
+          VdbeComment((v, "%s() by index",
+                (flag==WHERE_ORDERBY_MIN?"min":"max")));
+        }
+        sqlite3WhereEnd(pWInfo);
+        finalizeAggFunctions(pParse, &sAggInfo);
+      }
+
+      sSort.pOrderBy = 0;
+      sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL);
+      selectInnerLoop(pParse, p, p->pEList, -1, 0, 0, 
+                      pDest, addrEnd, addrEnd);
+      sqlite3ExprListDelete(db, pDel);
+    }
+    sqlite3VdbeResolveLabel(v, addrEnd);
+    
+  } /* endif aggregate query */
+
+  if( sDistinct.eTnctType==WHERE_DISTINCT_UNORDERED ){
+    explainTempTable(pParse, "DISTINCT");
+  }
+
+  /* If there is an ORDER BY clause, then we need to sort the results
+  ** and send them to the callback one by one.
+  */
+  if( sSort.pOrderBy ){
+    explainTempTable(pParse,
+                     sSort.nOBSat>0 ? "RIGHT PART OF ORDER BY":"ORDER BY");
+    generateSortTail(pParse, p, &sSort, pEList->nExpr, pDest);
+  }
+
+  /* Jump here to skip this query
+  */
+  sqlite3VdbeResolveLabel(v, iEnd);
+
+  /* The SELECT has been coded. If there is an error in the Parse structure,
+  ** set the return code to 1. Otherwise 0. */
+  rc = (pParse->nErr>0);
+
+  /* Control jumps to here if an error is encountered above, or upon
+  ** successful coding of the SELECT.
+  */
+select_end:
+  explainSetInteger(pParse->iSelectId, iRestoreSelectId);
+
+  /* Identify column names if results of the SELECT are to be output.
+  */
+  if( rc==SQLITE_OK && pDest->eDest==SRT_Output ){
+    generateColumnNames(pParse, pTabList, pEList);
+  }
+
+  sqlite3DbFree(db, sAggInfo.aCol);
+  sqlite3DbFree(db, sAggInfo.aFunc);
+#if SELECTTRACE_ENABLED
+  SELECTTRACE(1,pParse,p,("end processing\n"));
+  pParse->nSelectIndent--;
+#endif
+  return rc;
+}
+
+/************** End of select.c **********************************************/
+/************** Begin file table.c *******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the sqlite3_get_table() and sqlite3_free_table()
+** interface routines.  These are just wrappers around the main
+** interface routine of sqlite3_exec().
+**
+** These routines are in a separate files so that they will not be linked
+** if they are not used.
+*/
+/* #include "sqliteInt.h" */
+/* #include <stdlib.h> */
+/* #include <string.h> */
+
+#ifndef SQLITE_OMIT_GET_TABLE
+
+/*
+** This structure is used to pass data from sqlite3_get_table() through
+** to the callback function is uses to build the result.
+*/
+typedef struct TabResult {
+  char **azResult;   /* Accumulated output */
+  char *zErrMsg;     /* Error message text, if an error occurs */
+  u32 nAlloc;        /* Slots allocated for azResult[] */
+  u32 nRow;          /* Number of rows in the result */
+  u32 nColumn;       /* Number of columns in the result */
+  u32 nData;         /* Slots used in azResult[].  (nRow+1)*nColumn */
+  int rc;            /* Return code from sqlite3_exec() */
+} TabResult;
+
+/*
+** This routine is called once for each row in the result table.  Its job
+** is to fill in the TabResult structure appropriately, allocating new
+** memory as necessary.
+*/
+static int sqlite3_get_table_cb(void *pArg, int nCol, char **argv, char **colv){
+  TabResult *p = (TabResult*)pArg;  /* Result accumulator */
+  int need;                         /* Slots needed in p->azResult[] */
+  int i;                            /* Loop counter */
+  char *z;                          /* A single column of result */
+
+  /* Make sure there is enough space in p->azResult to hold everything
+  ** we need to remember from this invocation of the callback.
+  */
+  if( p->nRow==0 && argv!=0 ){
+    need = nCol*2;
+  }else{
+    need = nCol;
+  }
+  if( p->nData + need > p->nAlloc ){
+    char **azNew;
+    p->nAlloc = p->nAlloc*2 + need;
+    azNew = sqlite3_realloc64( p->azResult, sizeof(char*)*p->nAlloc );
+    if( azNew==0 ) goto malloc_failed;
+    p->azResult = azNew;
+  }
+
+  /* If this is the first row, then generate an extra row containing
+  ** the names of all columns.
+  */
+  if( p->nRow==0 ){
+    p->nColumn = nCol;
+    for(i=0; i<nCol; i++){
+      z = sqlite3_mprintf("%s", colv[i]);
+      if( z==0 ) goto malloc_failed;
+      p->azResult[p->nData++] = z;
+    }
+  }else if( (int)p->nColumn!=nCol ){
+    sqlite3_free(p->zErrMsg);
+    p->zErrMsg = sqlite3_mprintf(
+       "sqlite3_get_table() called with two or more incompatible queries"
+    );
+    p->rc = SQLITE_ERROR;
+    return 1;
+  }
+
+  /* Copy over the row data
+  */
+  if( argv!=0 ){
+    for(i=0; i<nCol; i++){
+      if( argv[i]==0 ){
+        z = 0;
+      }else{
+        int n = sqlite3Strlen30(argv[i])+1;
+        z = sqlite3_malloc64( n );
+        if( z==0 ) goto malloc_failed;
+        memcpy(z, argv[i], n);
+      }
+      p->azResult[p->nData++] = z;
+    }
+    p->nRow++;
+  }
+  return 0;
+
+malloc_failed:
+  p->rc = SQLITE_NOMEM_BKPT;
+  return 1;
+}
+
+/*
+** Query the database.  But instead of invoking a callback for each row,
+** malloc() for space to hold the result and return the entire results
+** at the conclusion of the call.
+**
+** The result that is written to ***pazResult is held in memory obtained
+** from malloc().  But the caller cannot free this memory directly.  
+** Instead, the entire table should be passed to sqlite3_free_table() when
+** the calling procedure is finished using it.
+*/
+SQLITE_API int sqlite3_get_table(
+  sqlite3 *db,                /* The database on which the SQL executes */
+  const char *zSql,           /* The SQL to be executed */
+  char ***pazResult,          /* Write the result table here */
+  int *pnRow,                 /* Write the number of rows in the result here */
+  int *pnColumn,              /* Write the number of columns of result here */
+  char **pzErrMsg             /* Write error messages here */
+){
+  int rc;
+  TabResult res;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) || pazResult==0 ) return SQLITE_MISUSE_BKPT;
+#endif
+  *pazResult = 0;
+  if( pnColumn ) *pnColumn = 0;
+  if( pnRow ) *pnRow = 0;
+  if( pzErrMsg ) *pzErrMsg = 0;
+  res.zErrMsg = 0;
+  res.nRow = 0;
+  res.nColumn = 0;
+  res.nData = 1;
+  res.nAlloc = 20;
+  res.rc = SQLITE_OK;
+  res.azResult = sqlite3_malloc64(sizeof(char*)*res.nAlloc );
+  if( res.azResult==0 ){
+     db->errCode = SQLITE_NOMEM;
+     return SQLITE_NOMEM_BKPT;
+  }
+  res.azResult[0] = 0;
+  rc = sqlite3_exec(db, zSql, sqlite3_get_table_cb, &res, pzErrMsg);
+  assert( sizeof(res.azResult[0])>= sizeof(res.nData) );
+  res.azResult[0] = SQLITE_INT_TO_PTR(res.nData);
+  if( (rc&0xff)==SQLITE_ABORT ){
+    sqlite3_free_table(&res.azResult[1]);
+    if( res.zErrMsg ){
+      if( pzErrMsg ){
+        sqlite3_free(*pzErrMsg);
+        *pzErrMsg = sqlite3_mprintf("%s",res.zErrMsg);
+      }
+      sqlite3_free(res.zErrMsg);
+    }
+    db->errCode = res.rc;  /* Assume 32-bit assignment is atomic */
+    return res.rc;
+  }
+  sqlite3_free(res.zErrMsg);
+  if( rc!=SQLITE_OK ){
+    sqlite3_free_table(&res.azResult[1]);
+    return rc;
+  }
+  if( res.nAlloc>res.nData ){
+    char **azNew;
+    azNew = sqlite3_realloc64( res.azResult, sizeof(char*)*res.nData );
+    if( azNew==0 ){
+      sqlite3_free_table(&res.azResult[1]);
+      db->errCode = SQLITE_NOMEM;
+      return SQLITE_NOMEM_BKPT;
+    }
+    res.azResult = azNew;
+  }
+  *pazResult = &res.azResult[1];
+  if( pnColumn ) *pnColumn = res.nColumn;
+  if( pnRow ) *pnRow = res.nRow;
+  return rc;
+}
+
+/*
+** This routine frees the space the sqlite3_get_table() malloced.
+*/
+SQLITE_API void sqlite3_free_table(
+  char **azResult            /* Result returned from sqlite3_get_table() */
+){
+  if( azResult ){
+    int i, n;
+    azResult--;
+    assert( azResult!=0 );
+    n = SQLITE_PTR_TO_INT(azResult[0]);
+    for(i=1; i<n; i++){ if( azResult[i] ) sqlite3_free(azResult[i]); }
+    sqlite3_free(azResult);
+  }
+}
+
+#endif /* SQLITE_OMIT_GET_TABLE */
+
+/************** End of table.c ***********************************************/
+/************** Begin file trigger.c *****************************************/
+/*
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the implementation for TRIGGERs
+*/
+/* #include "sqliteInt.h" */
+
+#ifndef SQLITE_OMIT_TRIGGER
+/*
+** Delete a linked list of TriggerStep structures.
+*/
+SQLITE_PRIVATE void sqlite3DeleteTriggerStep(sqlite3 *db, TriggerStep *pTriggerStep){
+  while( pTriggerStep ){
+    TriggerStep * pTmp = pTriggerStep;
+    pTriggerStep = pTriggerStep->pNext;
+
+    sqlite3ExprDelete(db, pTmp->pWhere);
+    sqlite3ExprListDelete(db, pTmp->pExprList);
+    sqlite3SelectDelete(db, pTmp->pSelect);
+    sqlite3IdListDelete(db, pTmp->pIdList);
+
+    sqlite3DbFree(db, pTmp);
+  }
+}
+
+/*
+** Given table pTab, return a list of all the triggers attached to 
+** the table. The list is connected by Trigger.pNext pointers.
+**
+** All of the triggers on pTab that are in the same database as pTab
+** are already attached to pTab->pTrigger.  But there might be additional
+** triggers on pTab in the TEMP schema.  This routine prepends all
+** TEMP triggers on pTab to the beginning of the pTab->pTrigger list
+** and returns the combined list.
+**
+** To state it another way:  This routine returns a list of all triggers
+** that fire off of pTab.  The list will include any TEMP triggers on
+** pTab as well as the triggers lised in pTab->pTrigger.
+*/
+SQLITE_PRIVATE Trigger *sqlite3TriggerList(Parse *pParse, Table *pTab){
+  Schema * const pTmpSchema = pParse->db->aDb[1].pSchema;
+  Trigger *pList = 0;                  /* List of triggers to return */
+
+  if( pParse->disableTriggers ){
+    return 0;
+  }
+
+  if( pTmpSchema!=pTab->pSchema ){
+    HashElem *p;
+    assert( sqlite3SchemaMutexHeld(pParse->db, 0, pTmpSchema) );
+    for(p=sqliteHashFirst(&pTmpSchema->trigHash); p; p=sqliteHashNext(p)){
+      Trigger *pTrig = (Trigger *)sqliteHashData(p);
+      if( pTrig->pTabSchema==pTab->pSchema
+       && 0==sqlite3StrICmp(pTrig->table, pTab->zName) 
+      ){
+        pTrig->pNext = (pList ? pList : pTab->pTrigger);
+        pList = pTrig;
+      }
+    }
+  }
+
+  return (pList ? pList : pTab->pTrigger);
+}
+
+/*
+** This is called by the parser when it sees a CREATE TRIGGER statement
+** up to the point of the BEGIN before the trigger actions.  A Trigger
+** structure is generated based on the information available and stored
+** in pParse->pNewTrigger.  After the trigger actions have been parsed, the
+** sqlite3FinishTrigger() function is called to complete the trigger
+** construction process.
+*/
+SQLITE_PRIVATE void sqlite3BeginTrigger(
+  Parse *pParse,      /* The parse context of the CREATE TRIGGER statement */
+  Token *pName1,      /* The name of the trigger */
+  Token *pName2,      /* The name of the trigger */
+  int tr_tm,          /* One of TK_BEFORE, TK_AFTER, TK_INSTEAD */
+  int op,             /* One of TK_INSERT, TK_UPDATE, TK_DELETE */
+  IdList *pColumns,   /* column list if this is an UPDATE OF trigger */
+  SrcList *pTableName,/* The name of the table/view the trigger applies to */
+  Expr *pWhen,        /* WHEN clause */
+  int isTemp,         /* True if the TEMPORARY keyword is present */
+  int noErr           /* Suppress errors if the trigger already exists */
+){
+  Trigger *pTrigger = 0;  /* The new trigger */
+  Table *pTab;            /* Table that the trigger fires off of */
+  char *zName = 0;        /* Name of the trigger */
+  sqlite3 *db = pParse->db;  /* The database connection */
+  int iDb;                /* The database to store the trigger in */
+  Token *pName;           /* The unqualified db name */
+  DbFixer sFix;           /* State vector for the DB fixer */
+
+  assert( pName1!=0 );   /* pName1->z might be NULL, but not pName1 itself */
+  assert( pName2!=0 );
+  assert( op==TK_INSERT || op==TK_UPDATE || op==TK_DELETE );
+  assert( op>0 && op<0xff );
+  if( isTemp ){
+    /* If TEMP was specified, then the trigger name may not be qualified. */
+    if( pName2->n>0 ){
+      sqlite3ErrorMsg(pParse, "temporary trigger may not have qualified name");
+      goto trigger_cleanup;
+    }
+    iDb = 1;
+    pName = pName1;
+  }else{
+    /* Figure out the db that the trigger will be created in */
+    iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pName);
+    if( iDb<0 ){
+      goto trigger_cleanup;
+    }
+  }
+  if( !pTableName || db->mallocFailed ){
+    goto trigger_cleanup;
+  }
+
+  /* A long-standing parser bug is that this syntax was allowed:
+  **
+  **    CREATE TRIGGER attached.demo AFTER INSERT ON attached.tab ....
+  **                                                 ^^^^^^^^
+  **
+  ** To maintain backwards compatibility, ignore the database
+  ** name on pTableName if we are reparsing out of SQLITE_MASTER.
+  */
+  if( db->init.busy && iDb!=1 ){
+    sqlite3DbFree(db, pTableName->a[0].zDatabase);
+    pTableName->a[0].zDatabase = 0;
+  }
+
+  /* If the trigger name was unqualified, and the table is a temp table,
+  ** then set iDb to 1 to create the trigger in the temporary database.
+  ** If sqlite3SrcListLookup() returns 0, indicating the table does not
+  ** exist, the error is caught by the block below.
+  */
+  pTab = sqlite3SrcListLookup(pParse, pTableName);
+  if( db->init.busy==0 && pName2->n==0 && pTab
+        && pTab->pSchema==db->aDb[1].pSchema ){
+    iDb = 1;
+  }
+
+  /* Ensure the table name matches database name and that the table exists */
+  if( db->mallocFailed ) goto trigger_cleanup;
+  assert( pTableName->nSrc==1 );
+  sqlite3FixInit(&sFix, pParse, iDb, "trigger", pName);
+  if( sqlite3FixSrcList(&sFix, pTableName) ){
+    goto trigger_cleanup;
+  }
+  pTab = sqlite3SrcListLookup(pParse, pTableName);
+  if( !pTab ){
+    /* The table does not exist. */
+    if( db->init.iDb==1 ){
+      /* Ticket #3810.
+      ** Normally, whenever a table is dropped, all associated triggers are
+      ** dropped too.  But if a TEMP trigger is created on a non-TEMP table
+      ** and the table is dropped by a different database connection, the
+      ** trigger is not visible to the database connection that does the
+      ** drop so the trigger cannot be dropped.  This results in an
+      ** "orphaned trigger" - a trigger whose associated table is missing.
+      */
+      db->init.orphanTrigger = 1;
+    }
+    goto trigger_cleanup;
+  }
+  if( IsVirtual(pTab) ){
+    sqlite3ErrorMsg(pParse, "cannot create triggers on virtual tables");
+    goto trigger_cleanup;
+  }
+
+  /* Check that the trigger name is not reserved and that no trigger of the
+  ** specified name exists */
+  zName = sqlite3NameFromToken(db, pName);
+  if( !zName || SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){
+    goto trigger_cleanup;
+  }
+  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+  if( sqlite3HashFind(&(db->aDb[iDb].pSchema->trigHash),zName) ){
+    if( !noErr ){
+      sqlite3ErrorMsg(pParse, "trigger %T already exists", pName);
+    }else{
+      assert( !db->init.busy );
+      sqlite3CodeVerifySchema(pParse, iDb);
+    }
+    goto trigger_cleanup;
+  }
+
+  /* Do not create a trigger on a system table */
+  if( sqlite3StrNICmp(pTab->zName, "sqlite_", 7)==0 ){
+    sqlite3ErrorMsg(pParse, "cannot create trigger on system table");
+    goto trigger_cleanup;
+  }
+
+  /* INSTEAD of triggers are only for views and views only support INSTEAD
+  ** of triggers.
+  */
+  if( pTab->pSelect && tr_tm!=TK_INSTEAD ){
+    sqlite3ErrorMsg(pParse, "cannot create %s trigger on view: %S", 
+        (tr_tm == TK_BEFORE)?"BEFORE":"AFTER", pTableName, 0);
+    goto trigger_cleanup;
+  }
+  if( !pTab->pSelect && tr_tm==TK_INSTEAD ){
+    sqlite3ErrorMsg(pParse, "cannot create INSTEAD OF"
+        " trigger on table: %S", pTableName, 0);
+    goto trigger_cleanup;
+  }
+
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  {
+    int iTabDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+    int code = SQLITE_CREATE_TRIGGER;
+    const char *zDb = db->aDb[iTabDb].zDbSName;
+    const char *zDbTrig = isTemp ? db->aDb[1].zDbSName : zDb;
+    if( iTabDb==1 || isTemp ) code = SQLITE_CREATE_TEMP_TRIGGER;
+    if( sqlite3AuthCheck(pParse, code, zName, pTab->zName, zDbTrig) ){
+      goto trigger_cleanup;
+    }
+    if( sqlite3AuthCheck(pParse, SQLITE_INSERT, SCHEMA_TABLE(iTabDb),0,zDb)){
+      goto trigger_cleanup;
+    }
+  }
+#endif
+
+  /* INSTEAD OF triggers can only appear on views and BEFORE triggers
+  ** cannot appear on views.  So we might as well translate every
+  ** INSTEAD OF trigger into a BEFORE trigger.  It simplifies code
+  ** elsewhere.
+  */
+  if (tr_tm == TK_INSTEAD){
+    tr_tm = TK_BEFORE;
+  }
+
+  /* Build the Trigger object */
+  pTrigger = (Trigger*)sqlite3DbMallocZero(db, sizeof(Trigger));
+  if( pTrigger==0 ) goto trigger_cleanup;
+  pTrigger->zName = zName;
+  zName = 0;
+  pTrigger->table = sqlite3DbStrDup(db, pTableName->a[0].zName);
+  pTrigger->pSchema = db->aDb[iDb].pSchema;
+  pTrigger->pTabSchema = pTab->pSchema;
+  pTrigger->op = (u8)op;
+  pTrigger->tr_tm = tr_tm==TK_BEFORE ? TRIGGER_BEFORE : TRIGGER_AFTER;
+  pTrigger->pWhen = sqlite3ExprDup(db, pWhen, EXPRDUP_REDUCE);
+  pTrigger->pColumns = sqlite3IdListDup(db, pColumns);
+  assert( pParse->pNewTrigger==0 );
+  pParse->pNewTrigger = pTrigger;
+
+trigger_cleanup:
+  sqlite3DbFree(db, zName);
+  sqlite3SrcListDelete(db, pTableName);
+  sqlite3IdListDelete(db, pColumns);
+  sqlite3ExprDelete(db, pWhen);
+  if( !pParse->pNewTrigger ){
+    sqlite3DeleteTrigger(db, pTrigger);
+  }else{
+    assert( pParse->pNewTrigger==pTrigger );
+  }
+}
+
+/*
+** This routine is called after all of the trigger actions have been parsed
+** in order to complete the process of building the trigger.
+*/
+SQLITE_PRIVATE void sqlite3FinishTrigger(
+  Parse *pParse,          /* Parser context */
+  TriggerStep *pStepList, /* The triggered program */
+  Token *pAll             /* Token that describes the complete CREATE TRIGGER */
+){
+  Trigger *pTrig = pParse->pNewTrigger;   /* Trigger being finished */
+  char *zName;                            /* Name of trigger */
+  sqlite3 *db = pParse->db;               /* The database */
+  DbFixer sFix;                           /* Fixer object */
+  int iDb;                                /* Database containing the trigger */
+  Token nameToken;                        /* Trigger name for error reporting */
+
+  pParse->pNewTrigger = 0;
+  if( NEVER(pParse->nErr) || !pTrig ) goto triggerfinish_cleanup;
+  zName = pTrig->zName;
+  iDb = sqlite3SchemaToIndex(pParse->db, pTrig->pSchema);
+  pTrig->step_list = pStepList;
+  while( pStepList ){
+    pStepList->pTrig = pTrig;
+    pStepList = pStepList->pNext;
+  }
+  sqlite3TokenInit(&nameToken, pTrig->zName);
+  sqlite3FixInit(&sFix, pParse, iDb, "trigger", &nameToken);
+  if( sqlite3FixTriggerStep(&sFix, pTrig->step_list) 
+   || sqlite3FixExpr(&sFix, pTrig->pWhen) 
+  ){
+    goto triggerfinish_cleanup;
+  }
+
+  /* if we are not initializing,
+  ** build the sqlite_master entry
+  */
+  if( !db->init.busy ){
+    Vdbe *v;
+    char *z;
+
+    /* Make an entry in the sqlite_master table */
+    v = sqlite3GetVdbe(pParse);
+    if( v==0 ) goto triggerfinish_cleanup;
+    sqlite3BeginWriteOperation(pParse, 0, iDb);
+    z = sqlite3DbStrNDup(db, (char*)pAll->z, pAll->n);
+    sqlite3NestedParse(pParse,
+       "INSERT INTO %Q.%s VALUES('trigger',%Q,%Q,0,'CREATE TRIGGER %q')",
+       db->aDb[iDb].zDbSName, SCHEMA_TABLE(iDb), zName,
+       pTrig->table, z);
+    sqlite3DbFree(db, z);
+    sqlite3ChangeCookie(pParse, iDb);
+    sqlite3VdbeAddParseSchemaOp(v, iDb,
+        sqlite3MPrintf(db, "type='trigger' AND name='%q'", zName));
+  }
+
+  if( db->init.busy ){
+    Trigger *pLink = pTrig;
+    Hash *pHash = &db->aDb[iDb].pSchema->trigHash;
+    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+    pTrig = sqlite3HashInsert(pHash, zName, pTrig);
+    if( pTrig ){
+      sqlite3OomFault(db);
+    }else if( pLink->pSchema==pLink->pTabSchema ){
+      Table *pTab;
+      pTab = sqlite3HashFind(&pLink->pTabSchema->tblHash, pLink->table);
+      assert( pTab!=0 );
+      pLink->pNext = pTab->pTrigger;
+      pTab->pTrigger = pLink;
+    }
+  }
+
+triggerfinish_cleanup:
+  sqlite3DeleteTrigger(db, pTrig);
+  assert( !pParse->pNewTrigger );
+  sqlite3DeleteTriggerStep(db, pStepList);
+}
+
+/*
+** Turn a SELECT statement (that the pSelect parameter points to) into
+** a trigger step.  Return a pointer to a TriggerStep structure.
+**
+** The parser calls this routine when it finds a SELECT statement in
+** body of a TRIGGER.  
+*/
+SQLITE_PRIVATE TriggerStep *sqlite3TriggerSelectStep(sqlite3 *db, Select *pSelect){
+  TriggerStep *pTriggerStep = sqlite3DbMallocZero(db, sizeof(TriggerStep));
+  if( pTriggerStep==0 ) {
+    sqlite3SelectDelete(db, pSelect);
+    return 0;
+  }
+  pTriggerStep->op = TK_SELECT;
+  pTriggerStep->pSelect = pSelect;
+  pTriggerStep->orconf = OE_Default;
+  return pTriggerStep;
+}
+
+/*
+** Allocate space to hold a new trigger step.  The allocated space
+** holds both the TriggerStep object and the TriggerStep.target.z string.
+**
+** If an OOM error occurs, NULL is returned and db->mallocFailed is set.
+*/
+static TriggerStep *triggerStepAllocate(
+  sqlite3 *db,                /* Database connection */
+  u8 op,                      /* Trigger opcode */
+  Token *pName                /* The target name */
+){
+  TriggerStep *pTriggerStep;
+
+  pTriggerStep = sqlite3DbMallocZero(db, sizeof(TriggerStep) + pName->n + 1);
+  if( pTriggerStep ){
+    char *z = (char*)&pTriggerStep[1];
+    memcpy(z, pName->z, pName->n);
+    sqlite3Dequote(z);
+    pTriggerStep->zTarget = z;
+    pTriggerStep->op = op;
+  }
+  return pTriggerStep;
+}
+
+/*
+** Build a trigger step out of an INSERT statement.  Return a pointer
+** to the new trigger step.
+**
+** The parser calls this routine when it sees an INSERT inside the
+** body of a trigger.
+*/
+SQLITE_PRIVATE TriggerStep *sqlite3TriggerInsertStep(
+  sqlite3 *db,        /* The database connection */
+  Token *pTableName,  /* Name of the table into which we insert */
+  IdList *pColumn,    /* List of columns in pTableName to insert into */
+  Select *pSelect,    /* A SELECT statement that supplies values */
+  u8 orconf           /* The conflict algorithm (OE_Abort, OE_Replace, etc.) */
+){
+  TriggerStep *pTriggerStep;
+
+  assert(pSelect != 0 || db->mallocFailed);
+
+  pTriggerStep = triggerStepAllocate(db, TK_INSERT, pTableName);
+  if( pTriggerStep ){
+    pTriggerStep->pSelect = sqlite3SelectDup(db, pSelect, EXPRDUP_REDUCE);
+    pTriggerStep->pIdList = pColumn;
+    pTriggerStep->orconf = orconf;
+  }else{
+    sqlite3IdListDelete(db, pColumn);
+  }
+  sqlite3SelectDelete(db, pSelect);
+
+  return pTriggerStep;
+}
+
+/*
+** Construct a trigger step that implements an UPDATE statement and return
+** a pointer to that trigger step.  The parser calls this routine when it
+** sees an UPDATE statement inside the body of a CREATE TRIGGER.
+*/
+SQLITE_PRIVATE TriggerStep *sqlite3TriggerUpdateStep(
+  sqlite3 *db,         /* The database connection */
+  Token *pTableName,   /* Name of the table to be updated */
+  ExprList *pEList,    /* The SET clause: list of column and new values */
+  Expr *pWhere,        /* The WHERE clause */
+  u8 orconf            /* The conflict algorithm. (OE_Abort, OE_Ignore, etc) */
+){
+  TriggerStep *pTriggerStep;
+
+  pTriggerStep = triggerStepAllocate(db, TK_UPDATE, pTableName);
+  if( pTriggerStep ){
+    pTriggerStep->pExprList = sqlite3ExprListDup(db, pEList, EXPRDUP_REDUCE);
+    pTriggerStep->pWhere = sqlite3ExprDup(db, pWhere, EXPRDUP_REDUCE);
+    pTriggerStep->orconf = orconf;
+  }
+  sqlite3ExprListDelete(db, pEList);
+  sqlite3ExprDelete(db, pWhere);
+  return pTriggerStep;
+}
+
+/*
+** Construct a trigger step that implements a DELETE statement and return
+** a pointer to that trigger step.  The parser calls this routine when it
+** sees a DELETE statement inside the body of a CREATE TRIGGER.
+*/
+SQLITE_PRIVATE TriggerStep *sqlite3TriggerDeleteStep(
+  sqlite3 *db,            /* Database connection */
+  Token *pTableName,      /* The table from which rows are deleted */
+  Expr *pWhere            /* The WHERE clause */
+){
+  TriggerStep *pTriggerStep;
+
+  pTriggerStep = triggerStepAllocate(db, TK_DELETE, pTableName);
+  if( pTriggerStep ){
+    pTriggerStep->pWhere = sqlite3ExprDup(db, pWhere, EXPRDUP_REDUCE);
+    pTriggerStep->orconf = OE_Default;
+  }
+  sqlite3ExprDelete(db, pWhere);
+  return pTriggerStep;
+}
+
+/* 
+** Recursively delete a Trigger structure
+*/
+SQLITE_PRIVATE void sqlite3DeleteTrigger(sqlite3 *db, Trigger *pTrigger){
+  if( pTrigger==0 ) return;
+  sqlite3DeleteTriggerStep(db, pTrigger->step_list);
+  sqlite3DbFree(db, pTrigger->zName);
+  sqlite3DbFree(db, pTrigger->table);
+  sqlite3ExprDelete(db, pTrigger->pWhen);
+  sqlite3IdListDelete(db, pTrigger->pColumns);
+  sqlite3DbFree(db, pTrigger);
+}
+
+/*
+** This function is called to drop a trigger from the database schema. 
+**
+** This may be called directly from the parser and therefore identifies
+** the trigger by name.  The sqlite3DropTriggerPtr() routine does the
+** same job as this routine except it takes a pointer to the trigger
+** instead of the trigger name.
+**/
+SQLITE_PRIVATE void sqlite3DropTrigger(Parse *pParse, SrcList *pName, int noErr){
+  Trigger *pTrigger = 0;
+  int i;
+  const char *zDb;
+  const char *zName;
+  sqlite3 *db = pParse->db;
+
+  if( db->mallocFailed ) goto drop_trigger_cleanup;
+  if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
+    goto drop_trigger_cleanup;
+  }
+
+  assert( pName->nSrc==1 );
+  zDb = pName->a[0].zDatabase;
+  zName = pName->a[0].zName;
+  assert( zDb!=0 || sqlite3BtreeHoldsAllMutexes(db) );
+  for(i=OMIT_TEMPDB; i<db->nDb; i++){
+    int j = (i<2) ? i^1 : i;  /* Search TEMP before MAIN */
+    if( zDb && sqlite3StrICmp(db->aDb[j].zDbSName, zDb) ) continue;
+    assert( sqlite3SchemaMutexHeld(db, j, 0) );
+    pTrigger = sqlite3HashFind(&(db->aDb[j].pSchema->trigHash), zName);
+    if( pTrigger ) break;
+  }
+  if( !pTrigger ){
+    if( !noErr ){
+      sqlite3ErrorMsg(pParse, "no such trigger: %S", pName, 0);
+    }else{
+      sqlite3CodeVerifyNamedSchema(pParse, zDb);
+    }
+    pParse->checkSchema = 1;
+    goto drop_trigger_cleanup;
+  }
+  sqlite3DropTriggerPtr(pParse, pTrigger);
+
+drop_trigger_cleanup:
+  sqlite3SrcListDelete(db, pName);
+}
+
+/*
+** Return a pointer to the Table structure for the table that a trigger
+** is set on.
+*/
+static Table *tableOfTrigger(Trigger *pTrigger){
+  return sqlite3HashFind(&pTrigger->pTabSchema->tblHash, pTrigger->table);
+}
+
+
+/*
+** Drop a trigger given a pointer to that trigger. 
+*/
+SQLITE_PRIVATE void sqlite3DropTriggerPtr(Parse *pParse, Trigger *pTrigger){
+  Table   *pTable;
+  Vdbe *v;
+  sqlite3 *db = pParse->db;
+  int iDb;
+
+  iDb = sqlite3SchemaToIndex(pParse->db, pTrigger->pSchema);
+  assert( iDb>=0 && iDb<db->nDb );
+  pTable = tableOfTrigger(pTrigger);
+  assert( pTable );
+  assert( pTable->pSchema==pTrigger->pSchema || iDb==1 );
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  {
+    int code = SQLITE_DROP_TRIGGER;
+    const char *zDb = db->aDb[iDb].zDbSName;
+    const char *zTab = SCHEMA_TABLE(iDb);
+    if( iDb==1 ) code = SQLITE_DROP_TEMP_TRIGGER;
+    if( sqlite3AuthCheck(pParse, code, pTrigger->zName, pTable->zName, zDb) ||
+      sqlite3AuthCheck(pParse, SQLITE_DELETE, zTab, 0, zDb) ){
+      return;
+    }
+  }
+#endif
+
+  /* Generate code to destroy the database record of the trigger.
+  */
+  assert( pTable!=0 );
+  if( (v = sqlite3GetVdbe(pParse))!=0 ){
+    sqlite3NestedParse(pParse,
+       "DELETE FROM %Q.%s WHERE name=%Q AND type='trigger'",
+       db->aDb[iDb].zDbSName, SCHEMA_TABLE(iDb), pTrigger->zName
+    );
+    sqlite3ChangeCookie(pParse, iDb);
+    sqlite3VdbeAddOp4(v, OP_DropTrigger, iDb, 0, 0, pTrigger->zName, 0);
+  }
+}
+
+/*
+** Remove a trigger from the hash tables of the sqlite* pointer.
+*/
+SQLITE_PRIVATE void sqlite3UnlinkAndDeleteTrigger(sqlite3 *db, int iDb, const char *zName){
+  Trigger *pTrigger;
+  Hash *pHash;
+
+  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+  pHash = &(db->aDb[iDb].pSchema->trigHash);
+  pTrigger = sqlite3HashInsert(pHash, zName, 0);
+  if( ALWAYS(pTrigger) ){
+    if( pTrigger->pSchema==pTrigger->pTabSchema ){
+      Table *pTab = tableOfTrigger(pTrigger);
+      Trigger **pp;
+      for(pp=&pTab->pTrigger; *pp!=pTrigger; pp=&((*pp)->pNext));
+      *pp = (*pp)->pNext;
+    }
+    sqlite3DeleteTrigger(db, pTrigger);
+    db->flags |= SQLITE_InternChanges;
+  }
+}
+
+/*
+** pEList is the SET clause of an UPDATE statement.  Each entry
+** in pEList is of the format <id>=<expr>.  If any of the entries
+** in pEList have an <id> which matches an identifier in pIdList,
+** then return TRUE.  If pIdList==NULL, then it is considered a
+** wildcard that matches anything.  Likewise if pEList==NULL then
+** it matches anything so always return true.  Return false only
+** if there is no match.
+*/
+static int checkColumnOverlap(IdList *pIdList, ExprList *pEList){
+  int e;
+  if( pIdList==0 || NEVER(pEList==0) ) return 1;
+  for(e=0; e<pEList->nExpr; e++){
+    if( sqlite3IdListIndex(pIdList, pEList->a[e].zName)>=0 ) return 1;
+  }
+  return 0; 
+}
+
+/*
+** Return a list of all triggers on table pTab if there exists at least
+** one trigger that must be fired when an operation of type 'op' is 
+** performed on the table, and, if that operation is an UPDATE, if at
+** least one of the columns in pChanges is being modified.
+*/
+SQLITE_PRIVATE Trigger *sqlite3TriggersExist(
+  Parse *pParse,          /* Parse context */
+  Table *pTab,            /* The table the contains the triggers */
+  int op,                 /* one of TK_DELETE, TK_INSERT, TK_UPDATE */
+  ExprList *pChanges,     /* Columns that change in an UPDATE statement */
+  int *pMask              /* OUT: Mask of TRIGGER_BEFORE|TRIGGER_AFTER */
+){
+  int mask = 0;
+  Trigger *pList = 0;
+  Trigger *p;
+
+  if( (pParse->db->flags & SQLITE_EnableTrigger)!=0 ){
+    pList = sqlite3TriggerList(pParse, pTab);
+  }
+  assert( pList==0 || IsVirtual(pTab)==0 );
+  for(p=pList; p; p=p->pNext){
+    if( p->op==op && checkColumnOverlap(p->pColumns, pChanges) ){
+      mask |= p->tr_tm;
+    }
+  }
+  if( pMask ){
+    *pMask = mask;
+  }
+  return (mask ? pList : 0);
+}
+
+/*
+** Convert the pStep->zTarget string into a SrcList and return a pointer
+** to that SrcList.
+**
+** This routine adds a specific database name, if needed, to the target when
+** forming the SrcList.  This prevents a trigger in one database from
+** referring to a target in another database.  An exception is when the
+** trigger is in TEMP in which case it can refer to any other database it
+** wants.
+*/
+static SrcList *targetSrcList(
+  Parse *pParse,       /* The parsing context */
+  TriggerStep *pStep   /* The trigger containing the target token */
+){
+  sqlite3 *db = pParse->db;
+  int iDb;             /* Index of the database to use */
+  SrcList *pSrc;       /* SrcList to be returned */
+
+  pSrc = sqlite3SrcListAppend(db, 0, 0, 0);
+  if( pSrc ){
+    assert( pSrc->nSrc>0 );
+    pSrc->a[pSrc->nSrc-1].zName = sqlite3DbStrDup(db, pStep->zTarget);
+    iDb = sqlite3SchemaToIndex(db, pStep->pTrig->pSchema);
+    if( iDb==0 || iDb>=2 ){
+      const char *zDb;
+      assert( iDb<db->nDb );
+      zDb = db->aDb[iDb].zDbSName;
+      pSrc->a[pSrc->nSrc-1].zDatabase =  sqlite3DbStrDup(db, zDb);
+    }
+  }
+  return pSrc;
+}
+
+/*
+** Generate VDBE code for the statements inside the body of a single 
+** trigger.
+*/
+static int codeTriggerProgram(
+  Parse *pParse,            /* The parser context */
+  TriggerStep *pStepList,   /* List of statements inside the trigger body */
+  int orconf                /* Conflict algorithm. (OE_Abort, etc) */  
+){
+  TriggerStep *pStep;
+  Vdbe *v = pParse->pVdbe;
+  sqlite3 *db = pParse->db;
+
+  assert( pParse->pTriggerTab && pParse->pToplevel );
+  assert( pStepList );
+  assert( v!=0 );
+  for(pStep=pStepList; pStep; pStep=pStep->pNext){
+    /* Figure out the ON CONFLICT policy that will be used for this step
+    ** of the trigger program. If the statement that caused this trigger
+    ** to fire had an explicit ON CONFLICT, then use it. Otherwise, use
+    ** the ON CONFLICT policy that was specified as part of the trigger
+    ** step statement. Example:
+    **
+    **   CREATE TRIGGER AFTER INSERT ON t1 BEGIN;
+    **     INSERT OR REPLACE INTO t2 VALUES(new.a, new.b);
+    **   END;
+    **
+    **   INSERT INTO t1 ... ;            -- insert into t2 uses REPLACE policy
+    **   INSERT OR IGNORE INTO t1 ... ;  -- insert into t2 uses IGNORE policy
+    */
+    pParse->eOrconf = (orconf==OE_Default)?pStep->orconf:(u8)orconf;
+    assert( pParse->okConstFactor==0 );
+
+    switch( pStep->op ){
+      case TK_UPDATE: {
+        sqlite3Update(pParse, 
+          targetSrcList(pParse, pStep),
+          sqlite3ExprListDup(db, pStep->pExprList, 0), 
+          sqlite3ExprDup(db, pStep->pWhere, 0), 
+          pParse->eOrconf
+        );
+        break;
+      }
+      case TK_INSERT: {
+        sqlite3Insert(pParse, 
+          targetSrcList(pParse, pStep),
+          sqlite3SelectDup(db, pStep->pSelect, 0), 
+          sqlite3IdListDup(db, pStep->pIdList), 
+          pParse->eOrconf
+        );
+        break;
+      }
+      case TK_DELETE: {
+        sqlite3DeleteFrom(pParse, 
+          targetSrcList(pParse, pStep),
+          sqlite3ExprDup(db, pStep->pWhere, 0)
+        );
+        break;
+      }
+      default: assert( pStep->op==TK_SELECT ); {
+        SelectDest sDest;
+        Select *pSelect = sqlite3SelectDup(db, pStep->pSelect, 0);
+        sqlite3SelectDestInit(&sDest, SRT_Discard, 0);
+        sqlite3Select(pParse, pSelect, &sDest);
+        sqlite3SelectDelete(db, pSelect);
+        break;
+      }
+    } 
+    if( pStep->op!=TK_SELECT ){
+      sqlite3VdbeAddOp0(v, OP_ResetCount);
+    }
+  }
+
+  return 0;
+}
+
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+/*
+** This function is used to add VdbeComment() annotations to a VDBE
+** program. It is not used in production code, only for debugging.
+*/
+static const char *onErrorText(int onError){
+  switch( onError ){
+    case OE_Abort:    return "abort";
+    case OE_Rollback: return "rollback";
+    case OE_Fail:     return "fail";
+    case OE_Replace:  return "replace";
+    case OE_Ignore:   return "ignore";
+    case OE_Default:  return "default";
+  }
+  return "n/a";
+}
+#endif
+
+/*
+** Parse context structure pFrom has just been used to create a sub-vdbe
+** (trigger program). If an error has occurred, transfer error information
+** from pFrom to pTo.
+*/
+static void transferParseError(Parse *pTo, Parse *pFrom){
+  assert( pFrom->zErrMsg==0 || pFrom->nErr );
+  assert( pTo->zErrMsg==0 || pTo->nErr );
+  if( pTo->nErr==0 ){
+    pTo->zErrMsg = pFrom->zErrMsg;
+    pTo->nErr = pFrom->nErr;
+    pTo->rc = pFrom->rc;
+  }else{
+    sqlite3DbFree(pFrom->db, pFrom->zErrMsg);
+  }
+}
+
+/*
+** Create and populate a new TriggerPrg object with a sub-program 
+** implementing trigger pTrigger with ON CONFLICT policy orconf.
+*/
+static TriggerPrg *codeRowTrigger(
+  Parse *pParse,       /* Current parse context */
+  Trigger *pTrigger,   /* Trigger to code */
+  Table *pTab,         /* The table pTrigger is attached to */
+  int orconf           /* ON CONFLICT policy to code trigger program with */
+){
+  Parse *pTop = sqlite3ParseToplevel(pParse);
+  sqlite3 *db = pParse->db;   /* Database handle */
+  TriggerPrg *pPrg;           /* Value to return */
+  Expr *pWhen = 0;            /* Duplicate of trigger WHEN expression */
+  Vdbe *v;                    /* Temporary VM */
+  NameContext sNC;            /* Name context for sub-vdbe */
+  SubProgram *pProgram = 0;   /* Sub-vdbe for trigger program */
+  Parse *pSubParse;           /* Parse context for sub-vdbe */
+  int iEndTrigger = 0;        /* Label to jump to if WHEN is false */
+
+  assert( pTrigger->zName==0 || pTab==tableOfTrigger(pTrigger) );
+  assert( pTop->pVdbe );
+
+  /* Allocate the TriggerPrg and SubProgram objects. To ensure that they
+  ** are freed if an error occurs, link them into the Parse.pTriggerPrg 
+  ** list of the top-level Parse object sooner rather than later.  */
+  pPrg = sqlite3DbMallocZero(db, sizeof(TriggerPrg));
+  if( !pPrg ) return 0;
+  pPrg->pNext = pTop->pTriggerPrg;
+  pTop->pTriggerPrg = pPrg;
+  pPrg->pProgram = pProgram = sqlite3DbMallocZero(db, sizeof(SubProgram));
+  if( !pProgram ) return 0;
+  sqlite3VdbeLinkSubProgram(pTop->pVdbe, pProgram);
+  pPrg->pTrigger = pTrigger;
+  pPrg->orconf = orconf;
+  pPrg->aColmask[0] = 0xffffffff;
+  pPrg->aColmask[1] = 0xffffffff;
+
+  /* Allocate and populate a new Parse context to use for coding the 
+  ** trigger sub-program.  */
+  pSubParse = sqlite3StackAllocZero(db, sizeof(Parse));
+  if( !pSubParse ) return 0;
+  memset(&sNC, 0, sizeof(sNC));
+  sNC.pParse = pSubParse;
+  pSubParse->db = db;
+  pSubParse->pTriggerTab = pTab;
+  pSubParse->pToplevel = pTop;
+  pSubParse->zAuthContext = pTrigger->zName;
+  pSubParse->eTriggerOp = pTrigger->op;
+  pSubParse->nQueryLoop = pParse->nQueryLoop;
+
+  v = sqlite3GetVdbe(pSubParse);
+  if( v ){
+    VdbeComment((v, "Start: %s.%s (%s %s%s%s ON %s)", 
+      pTrigger->zName, onErrorText(orconf),
+      (pTrigger->tr_tm==TRIGGER_BEFORE ? "BEFORE" : "AFTER"),
+        (pTrigger->op==TK_UPDATE ? "UPDATE" : ""),
+        (pTrigger->op==TK_INSERT ? "INSERT" : ""),
+        (pTrigger->op==TK_DELETE ? "DELETE" : ""),
+      pTab->zName
+    ));
+#ifndef SQLITE_OMIT_TRACE
+    sqlite3VdbeChangeP4(v, -1, 
+      sqlite3MPrintf(db, "-- TRIGGER %s", pTrigger->zName), P4_DYNAMIC
+    );
+#endif
+
+    /* If one was specified, code the WHEN clause. If it evaluates to false
+    ** (or NULL) the sub-vdbe is immediately halted by jumping to the 
+    ** OP_Halt inserted at the end of the program.  */
+    if( pTrigger->pWhen ){
+      pWhen = sqlite3ExprDup(db, pTrigger->pWhen, 0);
+      if( SQLITE_OK==sqlite3ResolveExprNames(&sNC, pWhen) 
+       && db->mallocFailed==0 
+      ){
+        iEndTrigger = sqlite3VdbeMakeLabel(v);
+        sqlite3ExprIfFalse(pSubParse, pWhen, iEndTrigger, SQLITE_JUMPIFNULL);
+      }
+      sqlite3ExprDelete(db, pWhen);
+    }
+
+    /* Code the trigger program into the sub-vdbe. */
+    codeTriggerProgram(pSubParse, pTrigger->step_list, orconf);
+
+    /* Insert an OP_Halt at the end of the sub-program. */
+    if( iEndTrigger ){
+      sqlite3VdbeResolveLabel(v, iEndTrigger);
+    }
+    sqlite3VdbeAddOp0(v, OP_Halt);
+    VdbeComment((v, "End: %s.%s", pTrigger->zName, onErrorText(orconf)));
+
+    transferParseError(pParse, pSubParse);
+    if( db->mallocFailed==0 ){
+      pProgram->aOp = sqlite3VdbeTakeOpArray(v, &pProgram->nOp, &pTop->nMaxArg);
+    }
+    pProgram->nMem = pSubParse->nMem;
+    pProgram->nCsr = pSubParse->nTab;
+    pProgram->token = (void *)pTrigger;
+    pPrg->aColmask[0] = pSubParse->oldmask;
+    pPrg->aColmask[1] = pSubParse->newmask;
+    sqlite3VdbeDelete(v);
+  }
+
+  assert( !pSubParse->pAinc       && !pSubParse->pZombieTab );
+  assert( !pSubParse->pTriggerPrg && !pSubParse->nMaxArg );
+  sqlite3ParserReset(pSubParse);
+  sqlite3StackFree(db, pSubParse);
+
+  return pPrg;
+}
+    
+/*
+** Return a pointer to a TriggerPrg object containing the sub-program for
+** trigger pTrigger with default ON CONFLICT algorithm orconf. If no such
+** TriggerPrg object exists, a new object is allocated and populated before
+** being returned.
+*/
+static TriggerPrg *getRowTrigger(
+  Parse *pParse,       /* Current parse context */
+  Trigger *pTrigger,   /* Trigger to code */
+  Table *pTab,         /* The table trigger pTrigger is attached to */
+  int orconf           /* ON CONFLICT algorithm. */
+){
+  Parse *pRoot = sqlite3ParseToplevel(pParse);
+  TriggerPrg *pPrg;
+
+  assert( pTrigger->zName==0 || pTab==tableOfTrigger(pTrigger) );
+
+  /* It may be that this trigger has already been coded (or is in the
+  ** process of being coded). If this is the case, then an entry with
+  ** a matching TriggerPrg.pTrigger field will be present somewhere
+  ** in the Parse.pTriggerPrg list. Search for such an entry.  */
+  for(pPrg=pRoot->pTriggerPrg; 
+      pPrg && (pPrg->pTrigger!=pTrigger || pPrg->orconf!=orconf); 
+      pPrg=pPrg->pNext
+  );
+
+  /* If an existing TriggerPrg could not be located, create a new one. */
+  if( !pPrg ){
+    pPrg = codeRowTrigger(pParse, pTrigger, pTab, orconf);
+  }
+
+  return pPrg;
+}
+
+/*
+** Generate code for the trigger program associated with trigger p on 
+** table pTab. The reg, orconf and ignoreJump parameters passed to this
+** function are the same as those described in the header function for
+** sqlite3CodeRowTrigger()
+*/
+SQLITE_PRIVATE void sqlite3CodeRowTriggerDirect(
+  Parse *pParse,       /* Parse context */
+  Trigger *p,          /* Trigger to code */
+  Table *pTab,         /* The table to code triggers from */
+  int reg,             /* Reg array containing OLD.* and NEW.* values */
+  int orconf,          /* ON CONFLICT policy */
+  int ignoreJump       /* Instruction to jump to for RAISE(IGNORE) */
+){
+  Vdbe *v = sqlite3GetVdbe(pParse); /* Main VM */
+  TriggerPrg *pPrg;
+  pPrg = getRowTrigger(pParse, p, pTab, orconf);
+  assert( pPrg || pParse->nErr || pParse->db->mallocFailed );
+
+  /* Code the OP_Program opcode in the parent VDBE. P4 of the OP_Program 
+  ** is a pointer to the sub-vdbe containing the trigger program.  */
+  if( pPrg ){
+    int bRecursive = (p->zName && 0==(pParse->db->flags&SQLITE_RecTriggers));
+
+    sqlite3VdbeAddOp4(v, OP_Program, reg, ignoreJump, ++pParse->nMem,
+                      (const char *)pPrg->pProgram, P4_SUBPROGRAM);
+    VdbeComment(
+        (v, "Call: %s.%s", (p->zName?p->zName:"fkey"), onErrorText(orconf)));
+
+    /* Set the P5 operand of the OP_Program instruction to non-zero if
+    ** recursive invocation of this trigger program is disallowed. Recursive
+    ** invocation is disallowed if (a) the sub-program is really a trigger,
+    ** not a foreign key action, and (b) the flag to enable recursive triggers
+    ** is clear.  */
+    sqlite3VdbeChangeP5(v, (u8)bRecursive);
+  }
+}
+
+/*
+** This is called to code the required FOR EACH ROW triggers for an operation
+** on table pTab. The operation to code triggers for (INSERT, UPDATE or DELETE)
+** is given by the op parameter. The tr_tm parameter determines whether the
+** BEFORE or AFTER triggers are coded. If the operation is an UPDATE, then
+** parameter pChanges is passed the list of columns being modified.
+**
+** If there are no triggers that fire at the specified time for the specified
+** operation on pTab, this function is a no-op.
+**
+** The reg argument is the address of the first in an array of registers 
+** that contain the values substituted for the new.* and old.* references
+** in the trigger program. If N is the number of columns in table pTab
+** (a copy of pTab->nCol), then registers are populated as follows:
+**
+**   Register       Contains
+**   ------------------------------------------------------
+**   reg+0          OLD.rowid
+**   reg+1          OLD.* value of left-most column of pTab
+**   ...            ...
+**   reg+N          OLD.* value of right-most column of pTab
+**   reg+N+1        NEW.rowid
+**   reg+N+2        OLD.* value of left-most column of pTab
+**   ...            ...
+**   reg+N+N+1      NEW.* value of right-most column of pTab
+**
+** For ON DELETE triggers, the registers containing the NEW.* values will
+** never be accessed by the trigger program, so they are not allocated or 
+** populated by the caller (there is no data to populate them with anyway). 
+** Similarly, for ON INSERT triggers the values stored in the OLD.* registers
+** are never accessed, and so are not allocated by the caller. So, for an
+** ON INSERT trigger, the value passed to this function as parameter reg
+** is not a readable register, although registers (reg+N) through 
+** (reg+N+N+1) are.
+**
+** Parameter orconf is the default conflict resolution algorithm for the
+** trigger program to use (REPLACE, IGNORE etc.). Parameter ignoreJump
+** is the instruction that control should jump to if a trigger program
+** raises an IGNORE exception.
+*/
+SQLITE_PRIVATE void sqlite3CodeRowTrigger(
+  Parse *pParse,       /* Parse context */
+  Trigger *pTrigger,   /* List of triggers on table pTab */
+  int op,              /* One of TK_UPDATE, TK_INSERT, TK_DELETE */
+  ExprList *pChanges,  /* Changes list for any UPDATE OF triggers */
+  int tr_tm,           /* One of TRIGGER_BEFORE, TRIGGER_AFTER */
+  Table *pTab,         /* The table to code triggers from */
+  int reg,             /* The first in an array of registers (see above) */
+  int orconf,          /* ON CONFLICT policy */
+  int ignoreJump       /* Instruction to jump to for RAISE(IGNORE) */
+){
+  Trigger *p;          /* Used to iterate through pTrigger list */
+
+  assert( op==TK_UPDATE || op==TK_INSERT || op==TK_DELETE );
+  assert( tr_tm==TRIGGER_BEFORE || tr_tm==TRIGGER_AFTER );
+  assert( (op==TK_UPDATE)==(pChanges!=0) );
+
+  for(p=pTrigger; p; p=p->pNext){
+
+    /* Sanity checking:  The schema for the trigger and for the table are
+    ** always defined.  The trigger must be in the same schema as the table
+    ** or else it must be a TEMP trigger. */
+    assert( p->pSchema!=0 );
+    assert( p->pTabSchema!=0 );
+    assert( p->pSchema==p->pTabSchema 
+         || p->pSchema==pParse->db->aDb[1].pSchema );
+
+    /* Determine whether we should code this trigger */
+    if( p->op==op 
+     && p->tr_tm==tr_tm 
+     && checkColumnOverlap(p->pColumns, pChanges)
+    ){
+      sqlite3CodeRowTriggerDirect(pParse, p, pTab, reg, orconf, ignoreJump);
+    }
+  }
+}
+
+/*
+** Triggers may access values stored in the old.* or new.* pseudo-table. 
+** This function returns a 32-bit bitmask indicating which columns of the 
+** old.* or new.* tables actually are used by triggers. This information 
+** may be used by the caller, for example, to avoid having to load the entire
+** old.* record into memory when executing an UPDATE or DELETE command.
+**
+** Bit 0 of the returned mask is set if the left-most column of the
+** table may be accessed using an [old|new].<col> reference. Bit 1 is set if
+** the second leftmost column value is required, and so on. If there
+** are more than 32 columns in the table, and at least one of the columns
+** with an index greater than 32 may be accessed, 0xffffffff is returned.
+**
+** It is not possible to determine if the old.rowid or new.rowid column is 
+** accessed by triggers. The caller must always assume that it is.
+**
+** Parameter isNew must be either 1 or 0. If it is 0, then the mask returned
+** applies to the old.* table. If 1, the new.* table.
+**
+** Parameter tr_tm must be a mask with one or both of the TRIGGER_BEFORE
+** and TRIGGER_AFTER bits set. Values accessed by BEFORE triggers are only
+** included in the returned mask if the TRIGGER_BEFORE bit is set in the
+** tr_tm parameter. Similarly, values accessed by AFTER triggers are only
+** included in the returned mask if the TRIGGER_AFTER bit is set in tr_tm.
+*/
+SQLITE_PRIVATE u32 sqlite3TriggerColmask(
+  Parse *pParse,       /* Parse context */
+  Trigger *pTrigger,   /* List of triggers on table pTab */
+  ExprList *pChanges,  /* Changes list for any UPDATE OF triggers */
+  int isNew,           /* 1 for new.* ref mask, 0 for old.* ref mask */
+  int tr_tm,           /* Mask of TRIGGER_BEFORE|TRIGGER_AFTER */
+  Table *pTab,         /* The table to code triggers from */
+  int orconf           /* Default ON CONFLICT policy for trigger steps */
+){
+  const int op = pChanges ? TK_UPDATE : TK_DELETE;
+  u32 mask = 0;
+  Trigger *p;
+
+  assert( isNew==1 || isNew==0 );
+  for(p=pTrigger; p; p=p->pNext){
+    if( p->op==op && (tr_tm&p->tr_tm)
+     && checkColumnOverlap(p->pColumns,pChanges)
+    ){
+      TriggerPrg *pPrg;
+      pPrg = getRowTrigger(pParse, p, pTab, orconf);
+      if( pPrg ){
+        mask |= pPrg->aColmask[isNew];
+      }
+    }
+  }
+
+  return mask;
+}
+
+#endif /* !defined(SQLITE_OMIT_TRIGGER) */
+
+/************** End of trigger.c *********************************************/
+/************** Begin file update.c ******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains C code routines that are called by the parser
+** to handle UPDATE statements.
+*/
+/* #include "sqliteInt.h" */
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/* Forward declaration */
+static void updateVirtualTable(
+  Parse *pParse,       /* The parsing context */
+  SrcList *pSrc,       /* The virtual table to be modified */
+  Table *pTab,         /* The virtual table */
+  ExprList *pChanges,  /* The columns to change in the UPDATE statement */
+  Expr *pRowidExpr,    /* Expression used to recompute the rowid */
+  int *aXRef,          /* Mapping from columns of pTab to entries in pChanges */
+  Expr *pWhere,        /* WHERE clause of the UPDATE statement */
+  int onError          /* ON CONFLICT strategy */
+);
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+/*
+** The most recently coded instruction was an OP_Column to retrieve the
+** i-th column of table pTab. This routine sets the P4 parameter of the 
+** OP_Column to the default value, if any.
+**
+** The default value of a column is specified by a DEFAULT clause in the 
+** column definition. This was either supplied by the user when the table
+** was created, or added later to the table definition by an ALTER TABLE
+** command. If the latter, then the row-records in the table btree on disk
+** may not contain a value for the column and the default value, taken
+** from the P4 parameter of the OP_Column instruction, is returned instead.
+** If the former, then all row-records are guaranteed to include a value
+** for the column and the P4 value is not required.
+**
+** Column definitions created by an ALTER TABLE command may only have 
+** literal default values specified: a number, null or a string. (If a more
+** complicated default expression value was provided, it is evaluated 
+** when the ALTER TABLE is executed and one of the literal values written
+** into the sqlite_master table.)
+**
+** Therefore, the P4 parameter is only required if the default value for
+** the column is a literal number, string or null. The sqlite3ValueFromExpr()
+** function is capable of transforming these types of expressions into
+** sqlite3_value objects.
+**
+** If parameter iReg is not negative, code an OP_RealAffinity instruction
+** on register iReg. This is used when an equivalent integer value is 
+** stored in place of an 8-byte floating point value in order to save 
+** space.
+*/
+SQLITE_PRIVATE void sqlite3ColumnDefault(Vdbe *v, Table *pTab, int i, int iReg){
+  assert( pTab!=0 );
+  if( !pTab->pSelect ){
+    sqlite3_value *pValue = 0;
+    u8 enc = ENC(sqlite3VdbeDb(v));
+    Column *pCol = &pTab->aCol[i];
+    VdbeComment((v, "%s.%s", pTab->zName, pCol->zName));
+    assert( i<pTab->nCol );
+    sqlite3ValueFromExpr(sqlite3VdbeDb(v), pCol->pDflt, enc, 
+                         pCol->affinity, &pValue);
+    if( pValue ){
+      sqlite3VdbeChangeP4(v, -1, (const char *)pValue, P4_MEM);
+    }
+#ifndef SQLITE_OMIT_FLOATING_POINT
+    if( pTab->aCol[i].affinity==SQLITE_AFF_REAL ){
+      sqlite3VdbeAddOp1(v, OP_RealAffinity, iReg);
+    }
+#endif
+  }
+}
+
+/*
+** Process an UPDATE statement.
+**
+**   UPDATE OR IGNORE table_wxyz SET a=b, c=d WHERE e<5 AND f NOT NULL;
+**          \_______/ \________/     \______/       \________________/
+*            onError   pTabList      pChanges             pWhere
+*/
+SQLITE_PRIVATE void sqlite3Update(
+  Parse *pParse,         /* The parser context */
+  SrcList *pTabList,     /* The table in which we should change things */
+  ExprList *pChanges,    /* Things to be changed */
+  Expr *pWhere,          /* The WHERE clause.  May be null */
+  int onError            /* How to handle constraint errors */
+){
+  int i, j;              /* Loop counters */
+  Table *pTab;           /* The table to be updated */
+  int addrTop = 0;       /* VDBE instruction address of the start of the loop */
+  WhereInfo *pWInfo;     /* Information about the WHERE clause */
+  Vdbe *v;               /* The virtual database engine */
+  Index *pIdx;           /* For looping over indices */
+  Index *pPk;            /* The PRIMARY KEY index for WITHOUT ROWID tables */
+  int nIdx;              /* Number of indices that need updating */
+  int iBaseCur;          /* Base cursor number */
+  int iDataCur;          /* Cursor for the canonical data btree */
+  int iIdxCur;           /* Cursor for the first index */
+  sqlite3 *db;           /* The database structure */
+  int *aRegIdx = 0;      /* One register assigned to each index to be updated */
+  int *aXRef = 0;        /* aXRef[i] is the index in pChanges->a[] of the
+                         ** an expression for the i-th column of the table.
+                         ** aXRef[i]==-1 if the i-th column is not changed. */
+  u8 *aToOpen;           /* 1 for tables and indices to be opened */
+  u8 chngPk;             /* PRIMARY KEY changed in a WITHOUT ROWID table */
+  u8 chngRowid;          /* Rowid changed in a normal table */
+  u8 chngKey;            /* Either chngPk or chngRowid */
+  Expr *pRowidExpr = 0;  /* Expression defining the new record number */
+  AuthContext sContext;  /* The authorization context */
+  NameContext sNC;       /* The name-context to resolve expressions in */
+  int iDb;               /* Database containing the table being updated */
+  int okOnePass;         /* True for one-pass algorithm without the FIFO */
+  int hasFK;             /* True if foreign key processing is required */
+  int labelBreak;        /* Jump here to break out of UPDATE loop */
+  int labelContinue;     /* Jump here to continue next step of UPDATE loop */
+
+#ifndef SQLITE_OMIT_TRIGGER
+  int isView;            /* True when updating a view (INSTEAD OF trigger) */
+  Trigger *pTrigger;     /* List of triggers on pTab, if required */
+  int tmask;             /* Mask of TRIGGER_BEFORE|TRIGGER_AFTER */
+#endif
+  int newmask;           /* Mask of NEW.* columns accessed by BEFORE triggers */
+  int iEph = 0;          /* Ephemeral table holding all primary key values */
+  int nKey = 0;          /* Number of elements in regKey for WITHOUT ROWID */
+  int aiCurOnePass[2];   /* The write cursors opened by WHERE_ONEPASS */
+
+  /* Register Allocations */
+  int regRowCount = 0;   /* A count of rows changed */
+  int regOldRowid = 0;   /* The old rowid */
+  int regNewRowid = 0;   /* The new rowid */
+  int regNew = 0;        /* Content of the NEW.* table in triggers */
+  int regOld = 0;        /* Content of OLD.* table in triggers */
+  int regRowSet = 0;     /* Rowset of rows to be updated */
+  int regKey = 0;        /* composite PRIMARY KEY value */
+
+  memset(&sContext, 0, sizeof(sContext));
+  db = pParse->db;
+  if( pParse->nErr || db->mallocFailed ){
+    goto update_cleanup;
+  }
+  assert( pTabList->nSrc==1 );
+
+  /* Locate the table which we want to update. 
+  */
+  pTab = sqlite3SrcListLookup(pParse, pTabList);
+  if( pTab==0 ) goto update_cleanup;
+  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
+
+  /* Figure out if we have any triggers and if the table being
+  ** updated is a view.
+  */
+#ifndef SQLITE_OMIT_TRIGGER
+  pTrigger = sqlite3TriggersExist(pParse, pTab, TK_UPDATE, pChanges, &tmask);
+  isView = pTab->pSelect!=0;
+  assert( pTrigger || tmask==0 );
+#else
+# define pTrigger 0
+# define isView 0
+# define tmask 0
+#endif
+#ifdef SQLITE_OMIT_VIEW
+# undef isView
+# define isView 0
+#endif
+
+  if( sqlite3ViewGetColumnNames(pParse, pTab) ){
+    goto update_cleanup;
+  }
+  if( sqlite3IsReadOnly(pParse, pTab, tmask) ){
+    goto update_cleanup;
+  }
+
+  /* Allocate a cursors for the main database table and for all indices.
+  ** The index cursors might not be used, but if they are used they
+  ** need to occur right after the database cursor.  So go ahead and
+  ** allocate enough space, just in case.
+  */
+  pTabList->a[0].iCursor = iBaseCur = iDataCur = pParse->nTab++;
+  iIdxCur = iDataCur+1;
+  pPk = HasRowid(pTab) ? 0 : sqlite3PrimaryKeyIndex(pTab);
+  for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdx++){
+    if( IsPrimaryKeyIndex(pIdx) && pPk!=0 ){
+      iDataCur = pParse->nTab;
+      pTabList->a[0].iCursor = iDataCur;
+    }
+    pParse->nTab++;
+  }
+
+  /* Allocate space for aXRef[], aRegIdx[], and aToOpen[].  
+  ** Initialize aXRef[] and aToOpen[] to their default values.
+  */
+  aXRef = sqlite3DbMallocRawNN(db, sizeof(int) * (pTab->nCol+nIdx) + nIdx+2 );
+  if( aXRef==0 ) goto update_cleanup;
+  aRegIdx = aXRef+pTab->nCol;
+  aToOpen = (u8*)(aRegIdx+nIdx);
+  memset(aToOpen, 1, nIdx+1);
+  aToOpen[nIdx+1] = 0;
+  for(i=0; i<pTab->nCol; i++) aXRef[i] = -1;
+
+  /* Initialize the name-context */
+  memset(&sNC, 0, sizeof(sNC));
+  sNC.pParse = pParse;
+  sNC.pSrcList = pTabList;
+
+  /* Resolve the column names in all the expressions of the
+  ** of the UPDATE statement.  Also find the column index
+  ** for each column to be updated in the pChanges array.  For each
+  ** column to be updated, make sure we have authorization to change
+  ** that column.
+  */
+  chngRowid = chngPk = 0;
+  for(i=0; i<pChanges->nExpr; i++){
+    if( sqlite3ResolveExprNames(&sNC, pChanges->a[i].pExpr) ){
+      goto update_cleanup;
+    }
+    for(j=0; j<pTab->nCol; j++){
+      if( sqlite3StrICmp(pTab->aCol[j].zName, pChanges->a[i].zName)==0 ){
+        if( j==pTab->iPKey ){
+          chngRowid = 1;
+          pRowidExpr = pChanges->a[i].pExpr;
+        }else if( pPk && (pTab->aCol[j].colFlags & COLFLAG_PRIMKEY)!=0 ){
+          chngPk = 1;
+        }
+        aXRef[j] = i;
+        break;
+      }
+    }
+    if( j>=pTab->nCol ){
+      if( pPk==0 && sqlite3IsRowid(pChanges->a[i].zName) ){
+        j = -1;
+        chngRowid = 1;
+        pRowidExpr = pChanges->a[i].pExpr;
+      }else{
+        sqlite3ErrorMsg(pParse, "no such column: %s", pChanges->a[i].zName);
+        pParse->checkSchema = 1;
+        goto update_cleanup;
+      }
+    }
+#ifndef SQLITE_OMIT_AUTHORIZATION
+    {
+      int rc;
+      rc = sqlite3AuthCheck(pParse, SQLITE_UPDATE, pTab->zName,
+                            j<0 ? "ROWID" : pTab->aCol[j].zName,
+                            db->aDb[iDb].zDbSName);
+      if( rc==SQLITE_DENY ){
+        goto update_cleanup;
+      }else if( rc==SQLITE_IGNORE ){
+        aXRef[j] = -1;
+      }
+    }
+#endif
+  }
+  assert( (chngRowid & chngPk)==0 );
+  assert( chngRowid==0 || chngRowid==1 );
+  assert( chngPk==0 || chngPk==1 );
+  chngKey = chngRowid + chngPk;
+
+  /* The SET expressions are not actually used inside the WHERE loop.  
+  ** So reset the colUsed mask. Unless this is a virtual table. In that
+  ** case, set all bits of the colUsed mask (to ensure that the virtual
+  ** table implementation makes all columns available).
+  */
+  pTabList->a[0].colUsed = IsVirtual(pTab) ? ALLBITS : 0;
+
+  hasFK = sqlite3FkRequired(pParse, pTab, aXRef, chngKey);
+
+  /* There is one entry in the aRegIdx[] array for each index on the table
+  ** being updated.  Fill in aRegIdx[] with a register number that will hold
+  ** the key for accessing each index.
+  **
+  ** FIXME:  Be smarter about omitting indexes that use expressions.
+  */
+  for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
+    int reg;
+    if( chngKey || hasFK || pIdx->pPartIdxWhere || pIdx==pPk ){
+      reg = ++pParse->nMem;
+    }else{
+      reg = 0;
+      for(i=0; i<pIdx->nKeyCol; i++){
+        i16 iIdxCol = pIdx->aiColumn[i];
+        if( iIdxCol<0 || aXRef[iIdxCol]>=0 ){
+          reg = ++pParse->nMem;
+          break;
+        }
+      }
+    }
+    if( reg==0 ) aToOpen[j+1] = 0;
+    aRegIdx[j] = reg;
+  }
+
+  /* Begin generating code. */
+  v = sqlite3GetVdbe(pParse);
+  if( v==0 ) goto update_cleanup;
+  if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
+  sqlite3BeginWriteOperation(pParse, 1, iDb);
+
+  /* Allocate required registers. */
+  if( !IsVirtual(pTab) ){
+    regRowSet = ++pParse->nMem;
+    regOldRowid = regNewRowid = ++pParse->nMem;
+    if( chngPk || pTrigger || hasFK ){
+      regOld = pParse->nMem + 1;
+      pParse->nMem += pTab->nCol;
+    }
+    if( chngKey || pTrigger || hasFK ){
+      regNewRowid = ++pParse->nMem;
+    }
+    regNew = pParse->nMem + 1;
+    pParse->nMem += pTab->nCol;
+  }
+
+  /* Start the view context. */
+  if( isView ){
+    sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
+  }
+
+  /* If we are trying to update a view, realize that view into
+  ** an ephemeral table.
+  */
+#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
+  if( isView ){
+    sqlite3MaterializeView(pParse, pTab, pWhere, iDataCur);
+  }
+#endif
+
+  /* Resolve the column names in all the expressions in the
+  ** WHERE clause.
+  */
+  if( sqlite3ResolveExprNames(&sNC, pWhere) ){
+    goto update_cleanup;
+  }
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  /* Virtual tables must be handled separately */
+  if( IsVirtual(pTab) ){
+    updateVirtualTable(pParse, pTabList, pTab, pChanges, pRowidExpr, aXRef,
+                       pWhere, onError);
+    goto update_cleanup;
+  }
+#endif
+
+  /* Begin the database scan
+  */
+  if( HasRowid(pTab) ){
+    sqlite3VdbeAddOp3(v, OP_Null, 0, regRowSet, regOldRowid);
+    pWInfo = sqlite3WhereBegin(
+        pParse, pTabList, pWhere, 0, 0,
+            WHERE_ONEPASS_DESIRED | WHERE_SEEK_TABLE, iIdxCur
+    );
+    if( pWInfo==0 ) goto update_cleanup;
+    okOnePass = sqlite3WhereOkOnePass(pWInfo, aiCurOnePass);
+  
+    /* Remember the rowid of every item to be updated.
+    */
+    sqlite3VdbeAddOp2(v, OP_Rowid, iDataCur, regOldRowid);
+    if( !okOnePass ){
+      sqlite3VdbeAddOp2(v, OP_RowSetAdd, regRowSet, regOldRowid);
+    }
+  
+    /* End the database scan loop.
+    */
+    sqlite3WhereEnd(pWInfo);
+  }else{
+    int iPk;         /* First of nPk memory cells holding PRIMARY KEY value */
+    i16 nPk;         /* Number of components of the PRIMARY KEY */
+    int addrOpen;    /* Address of the OpenEphemeral instruction */
+
+    assert( pPk!=0 );
+    nPk = pPk->nKeyCol;
+    iPk = pParse->nMem+1;
+    pParse->nMem += nPk;
+    regKey = ++pParse->nMem;
+    iEph = pParse->nTab++;
+    sqlite3VdbeAddOp2(v, OP_Null, 0, iPk);
+    addrOpen = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iEph, nPk);
+    sqlite3VdbeSetP4KeyInfo(pParse, pPk);
+    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0, 0, 
+                               WHERE_ONEPASS_DESIRED, iIdxCur);
+    if( pWInfo==0 ) goto update_cleanup;
+    okOnePass = sqlite3WhereOkOnePass(pWInfo, aiCurOnePass);
+    for(i=0; i<nPk; i++){
+      assert( pPk->aiColumn[i]>=0 );
+      sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, pPk->aiColumn[i],
+                                      iPk+i);
+    }
+    if( okOnePass ){
+      sqlite3VdbeChangeToNoop(v, addrOpen);
+      nKey = nPk;
+      regKey = iPk;
+    }else{
+      sqlite3VdbeAddOp4(v, OP_MakeRecord, iPk, nPk, regKey,
+                        sqlite3IndexAffinityStr(db, pPk), nPk);
+      sqlite3VdbeAddOp2(v, OP_IdxInsert, iEph, regKey);
+    }
+    sqlite3WhereEnd(pWInfo);
+  }
+
+  /* Initialize the count of updated rows
+  */
+  if( (db->flags & SQLITE_CountRows) && !pParse->pTriggerTab ){
+    regRowCount = ++pParse->nMem;
+    sqlite3VdbeAddOp2(v, OP_Integer, 0, regRowCount);
+  }
+
+  labelBreak = sqlite3VdbeMakeLabel(v);
+  if( !isView ){
+    /* 
+    ** Open every index that needs updating.  Note that if any
+    ** index could potentially invoke a REPLACE conflict resolution 
+    ** action, then we need to open all indices because we might need
+    ** to be deleting some records.
+    */
+    if( onError==OE_Replace ){
+      memset(aToOpen, 1, nIdx+1);
+    }else{
+      for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+        if( pIdx->onError==OE_Replace ){
+          memset(aToOpen, 1, nIdx+1);
+          break;
+        }
+      }
+    }
+    if( okOnePass ){
+      if( aiCurOnePass[0]>=0 ) aToOpen[aiCurOnePass[0]-iBaseCur] = 0;
+      if( aiCurOnePass[1]>=0 ) aToOpen[aiCurOnePass[1]-iBaseCur] = 0;
+    }
+    sqlite3OpenTableAndIndices(pParse, pTab, OP_OpenWrite, 0, iBaseCur, aToOpen,
+                               0, 0);
+  }
+
+  /* Top of the update loop */
+  if( okOnePass ){
+    if( aToOpen[iDataCur-iBaseCur] && !isView ){
+      assert( pPk );
+      sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, labelBreak, regKey, nKey);
+      VdbeCoverageNeverTaken(v);
+    }
+    labelContinue = labelBreak;
+    sqlite3VdbeAddOp2(v, OP_IsNull, pPk ? regKey : regOldRowid, labelBreak);
+    VdbeCoverageIf(v, pPk==0);
+    VdbeCoverageIf(v, pPk!=0);
+  }else if( pPk ){
+    labelContinue = sqlite3VdbeMakeLabel(v);
+    sqlite3VdbeAddOp2(v, OP_Rewind, iEph, labelBreak); VdbeCoverage(v);
+    addrTop = sqlite3VdbeAddOp2(v, OP_RowKey, iEph, regKey);
+    sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, labelContinue, regKey, 0);
+    VdbeCoverage(v);
+  }else{
+    labelContinue = sqlite3VdbeAddOp3(v, OP_RowSetRead, regRowSet, labelBreak,
+                             regOldRowid);
+    VdbeCoverage(v);
+    sqlite3VdbeAddOp3(v, OP_NotExists, iDataCur, labelContinue, regOldRowid);
+    VdbeCoverage(v);
+  }
+
+  /* If the record number will change, set register regNewRowid to
+  ** contain the new value. If the record number is not being modified,
+  ** then regNewRowid is the same register as regOldRowid, which is
+  ** already populated.  */
+  assert( chngKey || pTrigger || hasFK || regOldRowid==regNewRowid );
+  if( chngRowid ){
+    sqlite3ExprCode(pParse, pRowidExpr, regNewRowid);
+    sqlite3VdbeAddOp1(v, OP_MustBeInt, regNewRowid); VdbeCoverage(v);
+  }
+
+  /* Compute the old pre-UPDATE content of the row being changed, if that
+  ** information is needed */
+  if( chngPk || hasFK || pTrigger ){
+    u32 oldmask = (hasFK ? sqlite3FkOldmask(pParse, pTab) : 0);
+    oldmask |= sqlite3TriggerColmask(pParse, 
+        pTrigger, pChanges, 0, TRIGGER_BEFORE|TRIGGER_AFTER, pTab, onError
+    );
+    for(i=0; i<pTab->nCol; i++){
+      if( oldmask==0xffffffff
+       || (i<32 && (oldmask & MASKBIT32(i))!=0)
+       || (pTab->aCol[i].colFlags & COLFLAG_PRIMKEY)!=0
+      ){
+        testcase(  oldmask!=0xffffffff && i==31 );
+        sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, i, regOld+i);
+      }else{
+        sqlite3VdbeAddOp2(v, OP_Null, 0, regOld+i);
+      }
+    }
+    if( chngRowid==0 && pPk==0 ){
+      sqlite3VdbeAddOp2(v, OP_Copy, regOldRowid, regNewRowid);
+    }
+  }
+
+  /* Populate the array of registers beginning at regNew with the new
+  ** row data. This array is used to check constants, create the new
+  ** table and index records, and as the values for any new.* references
+  ** made by triggers.
+  **
+  ** If there are one or more BEFORE triggers, then do not populate the
+  ** registers associated with columns that are (a) not modified by
+  ** this UPDATE statement and (b) not accessed by new.* references. The
+  ** values for registers not modified by the UPDATE must be reloaded from 
+  ** the database after the BEFORE triggers are fired anyway (as the trigger 
+  ** may have modified them). So not loading those that are not going to
+  ** be used eliminates some redundant opcodes.
+  */
+  newmask = sqlite3TriggerColmask(
+      pParse, pTrigger, pChanges, 1, TRIGGER_BEFORE, pTab, onError
+  );
+  for(i=0; i<pTab->nCol; i++){
+    if( i==pTab->iPKey ){
+      sqlite3VdbeAddOp2(v, OP_Null, 0, regNew+i);
+    }else{
+      j = aXRef[i];
+      if( j>=0 ){
+        sqlite3ExprCode(pParse, pChanges->a[j].pExpr, regNew+i);
+      }else if( 0==(tmask&TRIGGER_BEFORE) || i>31 || (newmask & MASKBIT32(i)) ){
+        /* This branch loads the value of a column that will not be changed 
+        ** into a register. This is done if there are no BEFORE triggers, or
+        ** if there are one or more BEFORE triggers that use this value via
+        ** a new.* reference in a trigger program.
+        */
+        testcase( i==31 );
+        testcase( i==32 );
+        sqlite3ExprCodeGetColumnToReg(pParse, pTab, i, iDataCur, regNew+i);
+      }else{
+        sqlite3VdbeAddOp2(v, OP_Null, 0, regNew+i);
+      }
+    }
+  }
+
+  /* Fire any BEFORE UPDATE triggers. This happens before constraints are
+  ** verified. One could argue that this is wrong.
+  */
+  if( tmask&TRIGGER_BEFORE ){
+    sqlite3TableAffinity(v, pTab, regNew);
+    sqlite3CodeRowTrigger(pParse, pTrigger, TK_UPDATE, pChanges, 
+        TRIGGER_BEFORE, pTab, regOldRowid, onError, labelContinue);
+
+    /* The row-trigger may have deleted the row being updated. In this
+    ** case, jump to the next row. No updates or AFTER triggers are 
+    ** required. This behavior - what happens when the row being updated
+    ** is deleted or renamed by a BEFORE trigger - is left undefined in the
+    ** documentation.
+    */
+    if( pPk ){
+      sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, labelContinue,regKey,nKey);
+      VdbeCoverage(v);
+    }else{
+      sqlite3VdbeAddOp3(v, OP_NotExists, iDataCur, labelContinue, regOldRowid);
+      VdbeCoverage(v);
+    }
+
+    /* If it did not delete it, the row-trigger may still have modified 
+    ** some of the columns of the row being updated. Load the values for 
+    ** all columns not modified by the update statement into their 
+    ** registers in case this has happened.
+    */
+    for(i=0; i<pTab->nCol; i++){
+      if( aXRef[i]<0 && i!=pTab->iPKey ){
+        sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, i, regNew+i);
+      }
+    }
+  }
+
+  if( !isView ){
+    int addr1 = 0;        /* Address of jump instruction */
+    int bReplace = 0;     /* True if REPLACE conflict resolution might happen */
+
+    /* Do constraint checks. */
+    assert( regOldRowid>0 );
+    sqlite3GenerateConstraintChecks(pParse, pTab, aRegIdx, iDataCur, iIdxCur,
+        regNewRowid, regOldRowid, chngKey, onError, labelContinue, &bReplace,
+        aXRef);
+
+    /* Do FK constraint checks. */
+    if( hasFK ){
+      sqlite3FkCheck(pParse, pTab, regOldRowid, 0, aXRef, chngKey);
+    }
+
+    /* Delete the index entries associated with the current record.  */
+    if( bReplace || chngKey ){
+      if( pPk ){
+        addr1 = sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, 0, regKey, nKey);
+      }else{
+        addr1 = sqlite3VdbeAddOp3(v, OP_NotExists, iDataCur, 0, regOldRowid);
+      }
+      VdbeCoverageNeverTaken(v);
+    }
+    sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur, aRegIdx, -1);
+
+    /* If changing the rowid value, or if there are foreign key constraints
+    ** to process, delete the old record. Otherwise, add a noop OP_Delete
+    ** to invoke the pre-update hook.
+    **
+    ** That (regNew==regnewRowid+1) is true is also important for the 
+    ** pre-update hook. If the caller invokes preupdate_new(), the returned
+    ** value is copied from memory cell (regNewRowid+1+iCol), where iCol
+    ** is the column index supplied by the user.
+    */
+    assert( regNew==regNewRowid+1 );
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+    sqlite3VdbeAddOp3(v, OP_Delete, iDataCur,
+        OPFLAG_ISUPDATE | ((hasFK || chngKey || pPk!=0) ? 0 : OPFLAG_ISNOOP),
+        regNewRowid
+    );
+    if( !pParse->nested ){
+      sqlite3VdbeChangeP4(v, -1, (char*)pTab, P4_TABLE);
+    }
+#else
+    if( hasFK || chngKey || pPk!=0 ){
+      sqlite3VdbeAddOp2(v, OP_Delete, iDataCur, 0);
+    }
+#endif
+    if( bReplace || chngKey ){
+      sqlite3VdbeJumpHere(v, addr1);
+    }
+
+    if( hasFK ){
+      sqlite3FkCheck(pParse, pTab, 0, regNewRowid, aXRef, chngKey);
+    }
+  
+    /* Insert the new index entries and the new record. */
+    sqlite3CompleteInsertion(pParse, pTab, iDataCur, iIdxCur,
+                             regNewRowid, aRegIdx, 1, 0, 0);
+
+    /* Do any ON CASCADE, SET NULL or SET DEFAULT operations required to
+    ** handle rows (possibly in other tables) that refer via a foreign key
+    ** to the row just updated. */ 
+    if( hasFK ){
+      sqlite3FkActions(pParse, pTab, pChanges, regOldRowid, aXRef, chngKey);
+    }
+  }
+
+  /* Increment the row counter 
+  */
+  if( (db->flags & SQLITE_CountRows) && !pParse->pTriggerTab){
+    sqlite3VdbeAddOp2(v, OP_AddImm, regRowCount, 1);
+  }
+
+  sqlite3CodeRowTrigger(pParse, pTrigger, TK_UPDATE, pChanges, 
+      TRIGGER_AFTER, pTab, regOldRowid, onError, labelContinue);
+
+  /* Repeat the above with the next record to be updated, until
+  ** all record selected by the WHERE clause have been updated.
+  */
+  if( okOnePass ){
+    /* Nothing to do at end-of-loop for a single-pass */
+  }else if( pPk ){
+    sqlite3VdbeResolveLabel(v, labelContinue);
+    sqlite3VdbeAddOp2(v, OP_Next, iEph, addrTop); VdbeCoverage(v);
+  }else{
+    sqlite3VdbeGoto(v, labelContinue);
+  }
+  sqlite3VdbeResolveLabel(v, labelBreak);
+
+  /* Close all tables */
+  for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
+    assert( aRegIdx );
+    if( aToOpen[i+1] ){
+      sqlite3VdbeAddOp2(v, OP_Close, iIdxCur+i, 0);
+    }
+  }
+  if( iDataCur<iIdxCur ) sqlite3VdbeAddOp2(v, OP_Close, iDataCur, 0);
+
+  /* Update the sqlite_sequence table by storing the content of the
+  ** maximum rowid counter values recorded while inserting into
+  ** autoincrement tables.
+  */
+  if( pParse->nested==0 && pParse->pTriggerTab==0 ){
+    sqlite3AutoincrementEnd(pParse);
+  }
+
+  /*
+  ** Return the number of rows that were changed. If this routine is 
+  ** generating code because of a call to sqlite3NestedParse(), do not
+  ** invoke the callback function.
+  */
+  if( (db->flags&SQLITE_CountRows) && !pParse->pTriggerTab && !pParse->nested ){
+    sqlite3VdbeAddOp2(v, OP_ResultRow, regRowCount, 1);
+    sqlite3VdbeSetNumCols(v, 1);
+    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows updated", SQLITE_STATIC);
+  }
+
+update_cleanup:
+  sqlite3AuthContextPop(&sContext);
+  sqlite3DbFree(db, aXRef); /* Also frees aRegIdx[] and aToOpen[] */
+  sqlite3SrcListDelete(db, pTabList);
+  sqlite3ExprListDelete(db, pChanges);
+  sqlite3ExprDelete(db, pWhere);
+  return;
+}
+/* Make sure "isView" and other macros defined above are undefined. Otherwise
+** they may interfere with compilation of other functions in this file
+** (or in another file, if this file becomes part of the amalgamation).  */
+#ifdef isView
+ #undef isView
+#endif
+#ifdef pTrigger
+ #undef pTrigger
+#endif
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/*
+** Generate code for an UPDATE of a virtual table.
+**
+** There are two possible strategies - the default and the special 
+** "onepass" strategy. Onepass is only used if the virtual table 
+** implementation indicates that pWhere may match at most one row.
+**
+** The default strategy is to create an ephemeral table that contains
+** for each row to be changed:
+**
+**   (A)  The original rowid of that row.
+**   (B)  The revised rowid for the row.
+**   (C)  The content of every column in the row.
+**
+** Then loop through the contents of this ephemeral table executing a
+** VUpdate for each row. When finished, drop the ephemeral table.
+**
+** The "onepass" strategy does not use an ephemeral table. Instead, it
+** stores the same values (A, B and C above) in a register array and
+** makes a single invocation of VUpdate.
+*/
+static void updateVirtualTable(
+  Parse *pParse,       /* The parsing context */
+  SrcList *pSrc,       /* The virtual table to be modified */
+  Table *pTab,         /* The virtual table */
+  ExprList *pChanges,  /* The columns to change in the UPDATE statement */
+  Expr *pRowid,        /* Expression used to recompute the rowid */
+  int *aXRef,          /* Mapping from columns of pTab to entries in pChanges */
+  Expr *pWhere,        /* WHERE clause of the UPDATE statement */
+  int onError          /* ON CONFLICT strategy */
+){
+  Vdbe *v = pParse->pVdbe;  /* Virtual machine under construction */
+  int ephemTab;             /* Table holding the result of the SELECT */
+  int i;                    /* Loop counter */
+  sqlite3 *db = pParse->db; /* Database connection */
+  const char *pVTab = (const char*)sqlite3GetVTable(db, pTab);
+  WhereInfo *pWInfo;
+  int nArg = 2 + pTab->nCol;      /* Number of arguments to VUpdate */
+  int regArg;                     /* First register in VUpdate arg array */
+  int regRec;                     /* Register in which to assemble record */
+  int regRowid;                   /* Register for ephem table rowid */
+  int iCsr = pSrc->a[0].iCursor;  /* Cursor used for virtual table scan */
+  int aDummy[2];                  /* Unused arg for sqlite3WhereOkOnePass() */
+  int bOnePass;                   /* True to use onepass strategy */
+  int addr;                       /* Address of OP_OpenEphemeral */
+
+  /* Allocate nArg registers to martial the arguments to VUpdate. Then
+  ** create and open the ephemeral table in which the records created from
+  ** these arguments will be temporarily stored. */
+  assert( v );
+  ephemTab = pParse->nTab++;
+  addr= sqlite3VdbeAddOp2(v, OP_OpenEphemeral, ephemTab, nArg);
+  regArg = pParse->nMem + 1;
+  pParse->nMem += nArg;
+  regRec = ++pParse->nMem;
+  regRowid = ++pParse->nMem;
+
+  /* Start scanning the virtual table */
+  pWInfo = sqlite3WhereBegin(pParse, pSrc, pWhere, 0,0,WHERE_ONEPASS_DESIRED,0);
+  if( pWInfo==0 ) return;
+
+  /* Populate the argument registers. */
+  sqlite3VdbeAddOp2(v, OP_Rowid, iCsr, regArg);
+  if( pRowid ){
+    sqlite3ExprCode(pParse, pRowid, regArg+1);
+  }else{
+    sqlite3VdbeAddOp2(v, OP_Rowid, iCsr, regArg+1);
+  }
+  for(i=0; i<pTab->nCol; i++){
+    if( aXRef[i]>=0 ){
+      sqlite3ExprCode(pParse, pChanges->a[aXRef[i]].pExpr, regArg+2+i);
+    }else{
+      sqlite3VdbeAddOp3(v, OP_VColumn, iCsr, i, regArg+2+i);
+    }
+  }
+
+  bOnePass = sqlite3WhereOkOnePass(pWInfo, aDummy);
+
+  if( bOnePass ){
+    /* If using the onepass strategy, no-op out the OP_OpenEphemeral coded
+    ** above. Also, if this is a top-level parse (not a trigger), clear the
+    ** multi-write flag so that the VM does not open a statement journal */
+    sqlite3VdbeChangeToNoop(v, addr);
+    if( sqlite3IsToplevel(pParse) ){
+      pParse->isMultiWrite = 0;
+    }
+  }else{
+    /* Create a record from the argument register contents and insert it into
+    ** the ephemeral table. */
+    sqlite3VdbeAddOp3(v, OP_MakeRecord, regArg, nArg, regRec);
+    sqlite3VdbeAddOp2(v, OP_NewRowid, ephemTab, regRowid);
+    sqlite3VdbeAddOp3(v, OP_Insert, ephemTab, regRec, regRowid);
+  }
+
+
+  if( bOnePass==0 ){
+    /* End the virtual table scan */
+    sqlite3WhereEnd(pWInfo);
+
+    /* Begin scannning through the ephemeral table. */
+    addr = sqlite3VdbeAddOp1(v, OP_Rewind, ephemTab); VdbeCoverage(v);
+
+    /* Extract arguments from the current row of the ephemeral table and 
+    ** invoke the VUpdate method.  */
+    for(i=0; i<nArg; i++){
+      sqlite3VdbeAddOp3(v, OP_Column, ephemTab, i, regArg+i);
+    }
+  }
+  sqlite3VtabMakeWritable(pParse, pTab);
+  sqlite3VdbeAddOp4(v, OP_VUpdate, 0, nArg, regArg, pVTab, P4_VTAB);
+  sqlite3VdbeChangeP5(v, onError==OE_Default ? OE_Abort : onError);
+  sqlite3MayAbort(pParse);
+
+  /* End of the ephemeral table scan. Or, if using the onepass strategy,
+  ** jump to here if the scan visited zero rows. */
+  if( bOnePass==0 ){
+    sqlite3VdbeAddOp2(v, OP_Next, ephemTab, addr+1); VdbeCoverage(v);
+    sqlite3VdbeJumpHere(v, addr);
+    sqlite3VdbeAddOp2(v, OP_Close, ephemTab, 0);
+  }else{
+    sqlite3WhereEnd(pWInfo);
+  }
+}
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+/************** End of update.c **********************************************/
+/************** Begin file vacuum.c ******************************************/
+/*
+** 2003 April 6
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains code used to implement the VACUUM command.
+**
+** Most of the code in this file may be omitted by defining the
+** SQLITE_OMIT_VACUUM macro.
+*/
+/* #include "sqliteInt.h" */
+/* #include "vdbeInt.h" */
+
+#if !defined(SQLITE_OMIT_VACUUM) && !defined(SQLITE_OMIT_ATTACH)
+
+/*
+** Execute zSql on database db.
+**
+** If zSql returns rows, then each row will have exactly one
+** column.  (This will only happen if zSql begins with "SELECT".)
+** Take each row of result and call execSql() again recursively.
+**
+** The execSqlF() routine does the same thing, except it accepts
+** a format string as its third argument
+*/
+static int execSql(sqlite3 *db, char **pzErrMsg, const char *zSql){
+  sqlite3_stmt *pStmt;
+  int rc;
+
+  /* printf("SQL: [%s]\n", zSql); fflush(stdout); */
+  rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
+  if( rc!=SQLITE_OK ) return rc;
+  while( SQLITE_ROW==(rc = sqlite3_step(pStmt)) ){
+    const char *zSubSql = (const char*)sqlite3_column_text(pStmt,0);
+    assert( sqlite3_strnicmp(zSql,"SELECT",6)==0 );
+    if( zSubSql ){
+      assert( zSubSql[0]!='S' );
+      rc = execSql(db, pzErrMsg, zSubSql);
+      if( rc!=SQLITE_OK ) break;
+    }
+  }
+  assert( rc!=SQLITE_ROW );
+  if( rc==SQLITE_DONE ) rc = SQLITE_OK;
+  if( rc ){
+    sqlite3SetString(pzErrMsg, db, sqlite3_errmsg(db));
+  }
+  (void)sqlite3_finalize(pStmt);
+  return rc;
+}
+static int execSqlF(sqlite3 *db, char **pzErrMsg, const char *zSql, ...){
+  char *z;
+  va_list ap;
+  int rc;
+  va_start(ap, zSql);
+  z = sqlite3VMPrintf(db, zSql, ap);
+  va_end(ap);
+  if( z==0 ) return SQLITE_NOMEM;
+  rc = execSql(db, pzErrMsg, z);
+  sqlite3DbFree(db, z);
+  return rc;
+}
+
+/*
+** The VACUUM command is used to clean up the database,
+** collapse free space, etc.  It is modelled after the VACUUM command
+** in PostgreSQL.  The VACUUM command works as follows:
+**
+**   (1)  Create a new transient database file
+**   (2)  Copy all content from the database being vacuumed into
+**        the new transient database file
+**   (3)  Copy content from the transient database back into the
+**        original database.
+**
+** The transient database requires temporary disk space approximately
+** equal to the size of the original database.  The copy operation of
+** step (3) requires additional temporary disk space approximately equal
+** to the size of the original database for the rollback journal.
+** Hence, temporary disk space that is approximately 2x the size of the
+** original database is required.  Every page of the database is written
+** approximately 3 times:  Once for step (2) and twice for step (3).
+** Two writes per page are required in step (3) because the original
+** database content must be written into the rollback journal prior to
+** overwriting the database with the vacuumed content.
+**
+** Only 1x temporary space and only 1x writes would be required if
+** the copy of step (3) were replaced by deleting the original database
+** and renaming the transient database as the original.  But that will
+** not work if other processes are attached to the original database.
+** And a power loss in between deleting the original and renaming the
+** transient would cause the database file to appear to be deleted
+** following reboot.
+*/
+SQLITE_PRIVATE void sqlite3Vacuum(Parse *pParse, Token *pNm){
+  Vdbe *v = sqlite3GetVdbe(pParse);
+  int iDb = pNm ? sqlite3TwoPartName(pParse, pNm, pNm, &pNm) : 0;
+  if( v && (iDb>=2 || iDb==0) ){
+    sqlite3VdbeAddOp1(v, OP_Vacuum, iDb);
+    sqlite3VdbeUsesBtree(v, iDb);
+  }
+  return;
+}
+
+/*
+** This routine implements the OP_Vacuum opcode of the VDBE.
+*/
+SQLITE_PRIVATE int sqlite3RunVacuum(char **pzErrMsg, sqlite3 *db, int iDb){
+  int rc = SQLITE_OK;     /* Return code from service routines */
+  Btree *pMain;           /* The database being vacuumed */
+  Btree *pTemp;           /* The temporary database we vacuum into */
+  int saved_flags;        /* Saved value of the db->flags */
+  int saved_nChange;      /* Saved value of db->nChange */
+  int saved_nTotalChange; /* Saved value of db->nTotalChange */
+  u8 saved_mTrace;        /* Saved trace settings */
+  Db *pDb = 0;            /* Database to detach at end of vacuum */
+  int isMemDb;            /* True if vacuuming a :memory: database */
+  int nRes;               /* Bytes of reserved space at the end of each page */
+  int nDb;                /* Number of attached databases */
+  const char *zDbMain;    /* Schema name of database to vacuum */
+
+  if( !db->autoCommit ){
+    sqlite3SetString(pzErrMsg, db, "cannot VACUUM from within a transaction");
+    return SQLITE_ERROR;
+  }
+  if( db->nVdbeActive>1 ){
+    sqlite3SetString(pzErrMsg, db,"cannot VACUUM - SQL statements in progress");
+    return SQLITE_ERROR;
+  }
+
+  /* Save the current value of the database flags so that it can be 
+  ** restored before returning. Then set the writable-schema flag, and
+  ** disable CHECK and foreign key constraints.  */
+  saved_flags = db->flags;
+  saved_nChange = db->nChange;
+  saved_nTotalChange = db->nTotalChange;
+  saved_mTrace = db->mTrace;
+  db->flags |= (SQLITE_WriteSchema | SQLITE_IgnoreChecks
+                 | SQLITE_PreferBuiltin | SQLITE_Vacuum);
+  db->flags &= ~(SQLITE_ForeignKeys | SQLITE_ReverseOrder | SQLITE_CountRows);
+  db->mTrace = 0;
+
+  zDbMain = db->aDb[iDb].zDbSName;
+  pMain = db->aDb[iDb].pBt;
+  isMemDb = sqlite3PagerIsMemdb(sqlite3BtreePager(pMain));
+
+  /* Attach the temporary database as 'vacuum_db'. The synchronous pragma
+  ** can be set to 'off' for this file, as it is not recovered if a crash
+  ** occurs anyway. The integrity of the database is maintained by a
+  ** (possibly synchronous) transaction opened on the main database before
+  ** sqlite3BtreeCopyFile() is called.
+  **
+  ** An optimisation would be to use a non-journaled pager.
+  ** (Later:) I tried setting "PRAGMA vacuum_db.journal_mode=OFF" but
+  ** that actually made the VACUUM run slower.  Very little journalling
+  ** actually occurs when doing a vacuum since the vacuum_db is initially
+  ** empty.  Only the journal header is written.  Apparently it takes more
+  ** time to parse and run the PRAGMA to turn journalling off than it does
+  ** to write the journal header file.
+  */
+  nDb = db->nDb;
+  rc = execSql(db, pzErrMsg, "ATTACH''AS vacuum_db");
+  if( rc!=SQLITE_OK ) goto end_of_vacuum;
+  assert( (db->nDb-1)==nDb );
+  pDb = &db->aDb[nDb];
+  assert( strcmp(pDb->zDbSName,"vacuum_db")==0 );
+  pTemp = pDb->pBt;
+
+  /* The call to execSql() to attach the temp database has left the file
+  ** locked (as there was more than one active statement when the transaction
+  ** to read the schema was concluded. Unlock it here so that this doesn't
+  ** cause problems for the call to BtreeSetPageSize() below.  */
+  sqlite3BtreeCommit(pTemp);
+
+  nRes = sqlite3BtreeGetOptimalReserve(pMain);
+
+  /* A VACUUM cannot change the pagesize of an encrypted database. */
+#ifdef SQLITE_HAS_CODEC
+  if( db->nextPagesize ){
+    extern void sqlite3CodecGetKey(sqlite3*, int, void**, int*);
+    int nKey;
+    char *zKey;
+    sqlite3CodecGetKey(db, 0, (void**)&zKey, &nKey);
+    if( nKey ) db->nextPagesize = 0;
+  }
+#endif
+
+  sqlite3BtreeSetCacheSize(pTemp, db->aDb[iDb].pSchema->cache_size);
+  sqlite3BtreeSetSpillSize(pTemp, sqlite3BtreeSetSpillSize(pMain,0));
+  sqlite3BtreeSetPagerFlags(pTemp, PAGER_SYNCHRONOUS_OFF|PAGER_CACHESPILL);
+
+  /* Begin a transaction and take an exclusive lock on the main database
+  ** file. This is done before the sqlite3BtreeGetPageSize(pMain) call below,
+  ** to ensure that we do not try to change the page-size on a WAL database.
+  */
+  rc = execSql(db, pzErrMsg, "BEGIN");
+  if( rc!=SQLITE_OK ) goto end_of_vacuum;
+  rc = sqlite3BtreeBeginTrans(pMain, 2);
+  if( rc!=SQLITE_OK ) goto end_of_vacuum;
+
+  /* Do not attempt to change the page size for a WAL database */
+  if( sqlite3PagerGetJournalMode(sqlite3BtreePager(pMain))
+                                               ==PAGER_JOURNALMODE_WAL ){
+    db->nextPagesize = 0;
+  }
+
+  if( sqlite3BtreeSetPageSize(pTemp, sqlite3BtreeGetPageSize(pMain), nRes, 0)
+   || (!isMemDb && sqlite3BtreeSetPageSize(pTemp, db->nextPagesize, nRes, 0))
+   || NEVER(db->mallocFailed)
+  ){
+    rc = SQLITE_NOMEM_BKPT;
+    goto end_of_vacuum;
+  }
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+  sqlite3BtreeSetAutoVacuum(pTemp, db->nextAutovac>=0 ? db->nextAutovac :
+                                           sqlite3BtreeGetAutoVacuum(pMain));
+#endif
+
+  /* Query the schema of the main database. Create a mirror schema
+  ** in the temporary database.
+  */
+  db->init.iDb = nDb; /* force new CREATE statements into vacuum_db */
+  rc = execSqlF(db, pzErrMsg,
+      "SELECT sql FROM \"%w\".sqlite_master"
+      " WHERE type='table'AND name<>'sqlite_sequence'"
+      " AND coalesce(rootpage,1)>0",
+      zDbMain
+  );
+  if( rc!=SQLITE_OK ) goto end_of_vacuum;
+  rc = execSqlF(db, pzErrMsg,
+      "SELECT sql FROM \"%w\".sqlite_master"
+      " WHERE type='index' AND length(sql)>10",
+      zDbMain
+  );
+  if( rc!=SQLITE_OK ) goto end_of_vacuum;
+  db->init.iDb = 0;
+
+  /* Loop through the tables in the main database. For each, do
+  ** an "INSERT INTO vacuum_db.xxx SELECT * FROM main.xxx;" to copy
+  ** the contents to the temporary database.
+  */
+  rc = execSqlF(db, pzErrMsg,
+      "SELECT'INSERT INTO vacuum_db.'||quote(name)"
+      "||' SELECT*FROM\"%w\".'||quote(name)"
+      "FROM vacuum_db.sqlite_master "
+      "WHERE type='table'AND coalesce(rootpage,1)>0",
+      zDbMain
+  );
+  assert( (db->flags & SQLITE_Vacuum)!=0 );
+  db->flags &= ~SQLITE_Vacuum;
+  if( rc!=SQLITE_OK ) goto end_of_vacuum;
+
+  /* Copy the triggers, views, and virtual tables from the main database
+  ** over to the temporary database.  None of these objects has any
+  ** associated storage, so all we have to do is copy their entries
+  ** from the SQLITE_MASTER table.
+  */
+  rc = execSqlF(db, pzErrMsg,
+      "INSERT INTO vacuum_db.sqlite_master"
+      " SELECT*FROM \"%w\".sqlite_master"
+      " WHERE type IN('view','trigger')"
+      " OR(type='table'AND rootpage=0)",
+      zDbMain
+  );
+  if( rc ) goto end_of_vacuum;
+
+  /* At this point, there is a write transaction open on both the 
+  ** vacuum database and the main database. Assuming no error occurs,
+  ** both transactions are closed by this block - the main database
+  ** transaction by sqlite3BtreeCopyFile() and the other by an explicit
+  ** call to sqlite3BtreeCommit().
+  */
+  {
+    u32 meta;
+    int i;
+
+    /* This array determines which meta meta values are preserved in the
+    ** vacuum.  Even entries are the meta value number and odd entries
+    ** are an increment to apply to the meta value after the vacuum.
+    ** The increment is used to increase the schema cookie so that other
+    ** connections to the same database will know to reread the schema.
+    */
+    static const unsigned char aCopy[] = {
+       BTREE_SCHEMA_VERSION,     1,  /* Add one to the old schema cookie */
+       BTREE_DEFAULT_CACHE_SIZE, 0,  /* Preserve the default page cache size */
+       BTREE_TEXT_ENCODING,      0,  /* Preserve the text encoding */
+       BTREE_USER_VERSION,       0,  /* Preserve the user version */
+       BTREE_APPLICATION_ID,     0,  /* Preserve the application id */
+    };
+
+    assert( 1==sqlite3BtreeIsInTrans(pTemp) );
+    assert( 1==sqlite3BtreeIsInTrans(pMain) );
+
+    /* Copy Btree meta values */
+    for(i=0; i<ArraySize(aCopy); i+=2){
+      /* GetMeta() and UpdateMeta() cannot fail in this context because
+      ** we already have page 1 loaded into cache and marked dirty. */
+      sqlite3BtreeGetMeta(pMain, aCopy[i], &meta);
+      rc = sqlite3BtreeUpdateMeta(pTemp, aCopy[i], meta+aCopy[i+1]);
+      if( NEVER(rc!=SQLITE_OK) ) goto end_of_vacuum;
+    }
+
+    rc = sqlite3BtreeCopyFile(pMain, pTemp);
+    if( rc!=SQLITE_OK ) goto end_of_vacuum;
+    rc = sqlite3BtreeCommit(pTemp);
+    if( rc!=SQLITE_OK ) goto end_of_vacuum;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    sqlite3BtreeSetAutoVacuum(pMain, sqlite3BtreeGetAutoVacuum(pTemp));
+#endif
+  }
+
+  assert( rc==SQLITE_OK );
+  rc = sqlite3BtreeSetPageSize(pMain, sqlite3BtreeGetPageSize(pTemp), nRes,1);
+
+end_of_vacuum:
+  /* Restore the original value of db->flags */
+  db->init.iDb = 0;
+  db->flags = saved_flags;
+  db->nChange = saved_nChange;
+  db->nTotalChange = saved_nTotalChange;
+  db->mTrace = saved_mTrace;
+  sqlite3BtreeSetPageSize(pMain, -1, -1, 1);
+
+  /* Currently there is an SQL level transaction open on the vacuum
+  ** database. No locks are held on any other files (since the main file
+  ** was committed at the btree level). So it safe to end the transaction
+  ** by manually setting the autoCommit flag to true and detaching the
+  ** vacuum database. The vacuum_db journal file is deleted when the pager
+  ** is closed by the DETACH.
+  */
+  db->autoCommit = 1;
+
+  if( pDb ){
+    sqlite3BtreeClose(pDb->pBt);
+    pDb->pBt = 0;
+    pDb->pSchema = 0;
+  }
+
+  /* This both clears the schemas and reduces the size of the db->aDb[]
+  ** array. */ 
+  sqlite3ResetAllSchemasOfConnection(db);
+
+  return rc;
+}
+
+#endif  /* SQLITE_OMIT_VACUUM && SQLITE_OMIT_ATTACH */
+
+/************** End of vacuum.c **********************************************/
+/************** Begin file vtab.c ********************************************/
+/*
+** 2006 June 10
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains code used to help implement virtual tables.
+*/
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/* #include "sqliteInt.h" */
+
+/*
+** Before a virtual table xCreate() or xConnect() method is invoked, the
+** sqlite3.pVtabCtx member variable is set to point to an instance of
+** this struct allocated on the stack. It is used by the implementation of 
+** the sqlite3_declare_vtab() and sqlite3_vtab_config() APIs, both of which
+** are invoked only from within xCreate and xConnect methods.
+*/
+struct VtabCtx {
+  VTable *pVTable;    /* The virtual table being constructed */
+  Table *pTab;        /* The Table object to which the virtual table belongs */
+  VtabCtx *pPrior;    /* Parent context (if any) */
+  int bDeclared;      /* True after sqlite3_declare_vtab() is called */
+};
+
+/*
+** The actual function that does the work of creating a new module.
+** This function implements the sqlite3_create_module() and
+** sqlite3_create_module_v2() interfaces.
+*/
+static int createModule(
+  sqlite3 *db,                    /* Database in which module is registered */
+  const char *zName,              /* Name assigned to this module */
+  const sqlite3_module *pModule,  /* The definition of the module */
+  void *pAux,                     /* Context pointer for xCreate/xConnect */
+  void (*xDestroy)(void *)        /* Module destructor function */
+){
+  int rc = SQLITE_OK;
+  int nName;
+
+  sqlite3_mutex_enter(db->mutex);
+  nName = sqlite3Strlen30(zName);
+  if( sqlite3HashFind(&db->aModule, zName) ){
+    rc = SQLITE_MISUSE_BKPT;
+  }else{
+    Module *pMod;
+    pMod = (Module *)sqlite3DbMallocRawNN(db, sizeof(Module) + nName + 1);
+    if( pMod ){
+      Module *pDel;
+      char *zCopy = (char *)(&pMod[1]);
+      memcpy(zCopy, zName, nName+1);
+      pMod->zName = zCopy;
+      pMod->pModule = pModule;
+      pMod->pAux = pAux;
+      pMod->xDestroy = xDestroy;
+      pMod->pEpoTab = 0;
+      pDel = (Module *)sqlite3HashInsert(&db->aModule,zCopy,(void*)pMod);
+      assert( pDel==0 || pDel==pMod );
+      if( pDel ){
+        sqlite3OomFault(db);
+        sqlite3DbFree(db, pDel);
+      }
+    }
+  }
+  rc = sqlite3ApiExit(db, rc);
+  if( rc!=SQLITE_OK && xDestroy ) xDestroy(pAux);
+
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+
+/*
+** External API function used to create a new virtual-table module.
+*/
+SQLITE_API int sqlite3_create_module(
+  sqlite3 *db,                    /* Database in which module is registered */
+  const char *zName,              /* Name assigned to this module */
+  const sqlite3_module *pModule,  /* The definition of the module */
+  void *pAux                      /* Context pointer for xCreate/xConnect */
+){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) || zName==0 ) return SQLITE_MISUSE_BKPT;
+#endif
+  return createModule(db, zName, pModule, pAux, 0);
+}
+
+/*
+** External API function used to create a new virtual-table module.
+*/
+SQLITE_API int sqlite3_create_module_v2(
+  sqlite3 *db,                    /* Database in which module is registered */
+  const char *zName,              /* Name assigned to this module */
+  const sqlite3_module *pModule,  /* The definition of the module */
+  void *pAux,                     /* Context pointer for xCreate/xConnect */
+  void (*xDestroy)(void *)        /* Module destructor function */
+){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) || zName==0 ) return SQLITE_MISUSE_BKPT;
+#endif
+  return createModule(db, zName, pModule, pAux, xDestroy);
+}
+
+/*
+** Lock the virtual table so that it cannot be disconnected.
+** Locks nest.  Every lock should have a corresponding unlock.
+** If an unlock is omitted, resources leaks will occur.  
+**
+** If a disconnect is attempted while a virtual table is locked,
+** the disconnect is deferred until all locks have been removed.
+*/
+SQLITE_PRIVATE void sqlite3VtabLock(VTable *pVTab){
+  pVTab->nRef++;
+}
+
+
+/*
+** pTab is a pointer to a Table structure representing a virtual-table.
+** Return a pointer to the VTable object used by connection db to access 
+** this virtual-table, if one has been created, or NULL otherwise.
+*/
+SQLITE_PRIVATE VTable *sqlite3GetVTable(sqlite3 *db, Table *pTab){
+  VTable *pVtab;
+  assert( IsVirtual(pTab) );
+  for(pVtab=pTab->pVTable; pVtab && pVtab->db!=db; pVtab=pVtab->pNext);
+  return pVtab;
+}
+
+/*
+** Decrement the ref-count on a virtual table object. When the ref-count
+** reaches zero, call the xDisconnect() method to delete the object.
+*/
+SQLITE_PRIVATE void sqlite3VtabUnlock(VTable *pVTab){
+  sqlite3 *db = pVTab->db;
+
+  assert( db );
+  assert( pVTab->nRef>0 );
+  assert( db->magic==SQLITE_MAGIC_OPEN || db->magic==SQLITE_MAGIC_ZOMBIE );
+
+  pVTab->nRef--;
+  if( pVTab->nRef==0 ){
+    sqlite3_vtab *p = pVTab->pVtab;
+    if( p ){
+      p->pModule->xDisconnect(p);
+    }
+    sqlite3DbFree(db, pVTab);
+  }
+}
+
+/*
+** Table p is a virtual table. This function moves all elements in the
+** p->pVTable list to the sqlite3.pDisconnect lists of their associated
+** database connections to be disconnected at the next opportunity. 
+** Except, if argument db is not NULL, then the entry associated with
+** connection db is left in the p->pVTable list.
+*/
+static VTable *vtabDisconnectAll(sqlite3 *db, Table *p){
+  VTable *pRet = 0;
+  VTable *pVTable = p->pVTable;
+  p->pVTable = 0;
+
+  /* Assert that the mutex (if any) associated with the BtShared database 
+  ** that contains table p is held by the caller. See header comments 
+  ** above function sqlite3VtabUnlockList() for an explanation of why
+  ** this makes it safe to access the sqlite3.pDisconnect list of any
+  ** database connection that may have an entry in the p->pVTable list.
+  */
+  assert( db==0 || sqlite3SchemaMutexHeld(db, 0, p->pSchema) );
+
+  while( pVTable ){
+    sqlite3 *db2 = pVTable->db;
+    VTable *pNext = pVTable->pNext;
+    assert( db2 );
+    if( db2==db ){
+      pRet = pVTable;
+      p->pVTable = pRet;
+      pRet->pNext = 0;
+    }else{
+      pVTable->pNext = db2->pDisconnect;
+      db2->pDisconnect = pVTable;
+    }
+    pVTable = pNext;
+  }
+
+  assert( !db || pRet );
+  return pRet;
+}
+
+/*
+** Table *p is a virtual table. This function removes the VTable object
+** for table *p associated with database connection db from the linked
+** list in p->pVTab. It also decrements the VTable ref count. This is
+** used when closing database connection db to free all of its VTable
+** objects without disturbing the rest of the Schema object (which may
+** be being used by other shared-cache connections).
+*/
+SQLITE_PRIVATE void sqlite3VtabDisconnect(sqlite3 *db, Table *p){
+  VTable **ppVTab;
+
+  assert( IsVirtual(p) );
+  assert( sqlite3BtreeHoldsAllMutexes(db) );
+  assert( sqlite3_mutex_held(db->mutex) );
+
+  for(ppVTab=&p->pVTable; *ppVTab; ppVTab=&(*ppVTab)->pNext){
+    if( (*ppVTab)->db==db  ){
+      VTable *pVTab = *ppVTab;
+      *ppVTab = pVTab->pNext;
+      sqlite3VtabUnlock(pVTab);
+      break;
+    }
+  }
+}
+
+
+/*
+** Disconnect all the virtual table objects in the sqlite3.pDisconnect list.
+**
+** This function may only be called when the mutexes associated with all
+** shared b-tree databases opened using connection db are held by the 
+** caller. This is done to protect the sqlite3.pDisconnect list. The
+** sqlite3.pDisconnect list is accessed only as follows:
+**
+**   1) By this function. In this case, all BtShared mutexes and the mutex
+**      associated with the database handle itself must be held.
+**
+**   2) By function vtabDisconnectAll(), when it adds a VTable entry to
+**      the sqlite3.pDisconnect list. In this case either the BtShared mutex
+**      associated with the database the virtual table is stored in is held
+**      or, if the virtual table is stored in a non-sharable database, then
+**      the database handle mutex is held.
+**
+** As a result, a sqlite3.pDisconnect cannot be accessed simultaneously 
+** by multiple threads. It is thread-safe.
+*/
+SQLITE_PRIVATE void sqlite3VtabUnlockList(sqlite3 *db){
+  VTable *p = db->pDisconnect;
+  db->pDisconnect = 0;
+
+  assert( sqlite3BtreeHoldsAllMutexes(db) );
+  assert( sqlite3_mutex_held(db->mutex) );
+
+  if( p ){
+    sqlite3ExpirePreparedStatements(db);
+    do {
+      VTable *pNext = p->pNext;
+      sqlite3VtabUnlock(p);
+      p = pNext;
+    }while( p );
+  }
+}
+
+/*
+** Clear any and all virtual-table information from the Table record.
+** This routine is called, for example, just before deleting the Table
+** record.
+**
+** Since it is a virtual-table, the Table structure contains a pointer
+** to the head of a linked list of VTable structures. Each VTable 
+** structure is associated with a single sqlite3* user of the schema.
+** The reference count of the VTable structure associated with database 
+** connection db is decremented immediately (which may lead to the 
+** structure being xDisconnected and free). Any other VTable structures
+** in the list are moved to the sqlite3.pDisconnect list of the associated 
+** database connection.
+*/
+SQLITE_PRIVATE void sqlite3VtabClear(sqlite3 *db, Table *p){
+  if( !db || db->pnBytesFreed==0 ) vtabDisconnectAll(0, p);
+  if( p->azModuleArg ){
+    int i;
+    for(i=0; i<p->nModuleArg; i++){
+      if( i!=1 ) sqlite3DbFree(db, p->azModuleArg[i]);
+    }
+    sqlite3DbFree(db, p->azModuleArg);
+  }
+}
+
+/*
+** Add a new module argument to pTable->azModuleArg[].
+** The string is not copied - the pointer is stored.  The
+** string will be freed automatically when the table is
+** deleted.
+*/
+static void addModuleArgument(sqlite3 *db, Table *pTable, char *zArg){
+  int nBytes = sizeof(char *)*(2+pTable->nModuleArg);
+  char **azModuleArg;
+  azModuleArg = sqlite3DbRealloc(db, pTable->azModuleArg, nBytes);
+  if( azModuleArg==0 ){
+    sqlite3DbFree(db, zArg);
+  }else{
+    int i = pTable->nModuleArg++;
+    azModuleArg[i] = zArg;
+    azModuleArg[i+1] = 0;
+    pTable->azModuleArg = azModuleArg;
+  }
+}
+
+/*
+** The parser calls this routine when it first sees a CREATE VIRTUAL TABLE
+** statement.  The module name has been parsed, but the optional list
+** of parameters that follow the module name are still pending.
+*/
+SQLITE_PRIVATE void sqlite3VtabBeginParse(
+  Parse *pParse,        /* Parsing context */
+  Token *pName1,        /* Name of new table, or database name */
+  Token *pName2,        /* Name of new table or NULL */
+  Token *pModuleName,   /* Name of the module for the virtual table */
+  int ifNotExists       /* No error if the table already exists */
+){
+  int iDb;              /* The database the table is being created in */
+  Table *pTable;        /* The new virtual table */
+  sqlite3 *db;          /* Database connection */
+
+  sqlite3StartTable(pParse, pName1, pName2, 0, 0, 1, ifNotExists);
+  pTable = pParse->pNewTable;
+  if( pTable==0 ) return;
+  assert( 0==pTable->pIndex );
+
+  db = pParse->db;
+  iDb = sqlite3SchemaToIndex(db, pTable->pSchema);
+  assert( iDb>=0 );
+
+  pTable->tabFlags |= TF_Virtual;
+  pTable->nModuleArg = 0;
+  addModuleArgument(db, pTable, sqlite3NameFromToken(db, pModuleName));
+  addModuleArgument(db, pTable, 0);
+  addModuleArgument(db, pTable, sqlite3DbStrDup(db, pTable->zName));
+  assert( (pParse->sNameToken.z==pName2->z && pName2->z!=0)
+       || (pParse->sNameToken.z==pName1->z && pName2->z==0)
+  );
+  pParse->sNameToken.n = (int)(
+      &pModuleName->z[pModuleName->n] - pParse->sNameToken.z
+  );
+
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  /* Creating a virtual table invokes the authorization callback twice.
+  ** The first invocation, to obtain permission to INSERT a row into the
+  ** sqlite_master table, has already been made by sqlite3StartTable().
+  ** The second call, to obtain permission to create the table, is made now.
+  */
+  if( pTable->azModuleArg ){
+    sqlite3AuthCheck(pParse, SQLITE_CREATE_VTABLE, pTable->zName, 
+            pTable->azModuleArg[0], pParse->db->aDb[iDb].zDbSName);
+  }
+#endif
+}
+
+/*
+** This routine takes the module argument that has been accumulating
+** in pParse->zArg[] and appends it to the list of arguments on the
+** virtual table currently under construction in pParse->pTable.
+*/
+static void addArgumentToVtab(Parse *pParse){
+  if( pParse->sArg.z && pParse->pNewTable ){
+    const char *z = (const char*)pParse->sArg.z;
+    int n = pParse->sArg.n;
+    sqlite3 *db = pParse->db;
+    addModuleArgument(db, pParse->pNewTable, sqlite3DbStrNDup(db, z, n));
+  }
+}
+
+/*
+** The parser calls this routine after the CREATE VIRTUAL TABLE statement
+** has been completely parsed.
+*/
+SQLITE_PRIVATE void sqlite3VtabFinishParse(Parse *pParse, Token *pEnd){
+  Table *pTab = pParse->pNewTable;  /* The table being constructed */
+  sqlite3 *db = pParse->db;         /* The database connection */
+
+  if( pTab==0 ) return;
+  addArgumentToVtab(pParse);
+  pParse->sArg.z = 0;
+  if( pTab->nModuleArg<1 ) return;
+  
+  /* If the CREATE VIRTUAL TABLE statement is being entered for the
+  ** first time (in other words if the virtual table is actually being
+  ** created now instead of just being read out of sqlite_master) then
+  ** do additional initialization work and store the statement text
+  ** in the sqlite_master table.
+  */
+  if( !db->init.busy ){
+    char *zStmt;
+    char *zWhere;
+    int iDb;
+    int iReg;
+    Vdbe *v;
+
+    /* Compute the complete text of the CREATE VIRTUAL TABLE statement */
+    if( pEnd ){
+      pParse->sNameToken.n = (int)(pEnd->z - pParse->sNameToken.z) + pEnd->n;
+    }
+    zStmt = sqlite3MPrintf(db, "CREATE VIRTUAL TABLE %T", &pParse->sNameToken);
+
+    /* A slot for the record has already been allocated in the 
+    ** SQLITE_MASTER table.  We just need to update that slot with all
+    ** the information we've collected.  
+    **
+    ** The VM register number pParse->regRowid holds the rowid of an
+    ** entry in the sqlite_master table tht was created for this vtab
+    ** by sqlite3StartTable().
+    */
+    iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+    sqlite3NestedParse(pParse,
+      "UPDATE %Q.%s "
+         "SET type='table', name=%Q, tbl_name=%Q, rootpage=0, sql=%Q "
+       "WHERE rowid=#%d",
+      db->aDb[iDb].zDbSName, SCHEMA_TABLE(iDb),
+      pTab->zName,
+      pTab->zName,
+      zStmt,
+      pParse->regRowid
+    );
+    sqlite3DbFree(db, zStmt);
+    v = sqlite3GetVdbe(pParse);
+    sqlite3ChangeCookie(pParse, iDb);
+
+    sqlite3VdbeAddOp0(v, OP_Expire);
+    zWhere = sqlite3MPrintf(db, "name='%q' AND type='table'", pTab->zName);
+    sqlite3VdbeAddParseSchemaOp(v, iDb, zWhere);
+
+    iReg = ++pParse->nMem;
+    sqlite3VdbeLoadString(v, iReg, pTab->zName);
+    sqlite3VdbeAddOp2(v, OP_VCreate, iDb, iReg);
+  }
+
+  /* If we are rereading the sqlite_master table create the in-memory
+  ** record of the table. The xConnect() method is not called until
+  ** the first time the virtual table is used in an SQL statement. This
+  ** allows a schema that contains virtual tables to be loaded before
+  ** the required virtual table implementations are registered.  */
+  else {
+    Table *pOld;
+    Schema *pSchema = pTab->pSchema;
+    const char *zName = pTab->zName;
+    assert( sqlite3SchemaMutexHeld(db, 0, pSchema) );
+    pOld = sqlite3HashInsert(&pSchema->tblHash, zName, pTab);
+    if( pOld ){
+      sqlite3OomFault(db);
+      assert( pTab==pOld );  /* Malloc must have failed inside HashInsert() */
+      return;
+    }
+    pParse->pNewTable = 0;
+  }
+}
+
+/*
+** The parser calls this routine when it sees the first token
+** of an argument to the module name in a CREATE VIRTUAL TABLE statement.
+*/
+SQLITE_PRIVATE void sqlite3VtabArgInit(Parse *pParse){
+  addArgumentToVtab(pParse);
+  pParse->sArg.z = 0;
+  pParse->sArg.n = 0;
+}
+
+/*
+** The parser calls this routine for each token after the first token
+** in an argument to the module name in a CREATE VIRTUAL TABLE statement.
+*/
+SQLITE_PRIVATE void sqlite3VtabArgExtend(Parse *pParse, Token *p){
+  Token *pArg = &pParse->sArg;
+  if( pArg->z==0 ){
+    pArg->z = p->z;
+    pArg->n = p->n;
+  }else{
+    assert(pArg->z <= p->z);
+    pArg->n = (int)(&p->z[p->n] - pArg->z);
+  }
+}
+
+/*
+** Invoke a virtual table constructor (either xCreate or xConnect). The
+** pointer to the function to invoke is passed as the fourth parameter
+** to this procedure.
+*/
+static int vtabCallConstructor(
+  sqlite3 *db, 
+  Table *pTab,
+  Module *pMod,
+  int (*xConstruct)(sqlite3*,void*,int,const char*const*,sqlite3_vtab**,char**),
+  char **pzErr
+){
+  VtabCtx sCtx;
+  VTable *pVTable;
+  int rc;
+  const char *const*azArg = (const char *const*)pTab->azModuleArg;
+  int nArg = pTab->nModuleArg;
+  char *zErr = 0;
+  char *zModuleName;
+  int iDb;
+  VtabCtx *pCtx;
+
+  /* Check that the virtual-table is not already being initialized */
+  for(pCtx=db->pVtabCtx; pCtx; pCtx=pCtx->pPrior){
+    if( pCtx->pTab==pTab ){
+      *pzErr = sqlite3MPrintf(db, 
+          "vtable constructor called recursively: %s", pTab->zName
+      );
+      return SQLITE_LOCKED;
+    }
+  }
+
+  zModuleName = sqlite3MPrintf(db, "%s", pTab->zName);
+  if( !zModuleName ){
+    return SQLITE_NOMEM_BKPT;
+  }
+
+  pVTable = sqlite3DbMallocZero(db, sizeof(VTable));
+  if( !pVTable ){
+    sqlite3DbFree(db, zModuleName);
+    return SQLITE_NOMEM_BKPT;
+  }
+  pVTable->db = db;
+  pVTable->pMod = pMod;
+
+  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+  pTab->azModuleArg[1] = db->aDb[iDb].zDbSName;
+
+  /* Invoke the virtual table constructor */
+  assert( &db->pVtabCtx );
+  assert( xConstruct );
+  sCtx.pTab = pTab;
+  sCtx.pVTable = pVTable;
+  sCtx.pPrior = db->pVtabCtx;
+  sCtx.bDeclared = 0;
+  db->pVtabCtx = &sCtx;
+  rc = xConstruct(db, pMod->pAux, nArg, azArg, &pVTable->pVtab, &zErr);
+  db->pVtabCtx = sCtx.pPrior;
+  if( rc==SQLITE_NOMEM ) sqlite3OomFault(db);
+  assert( sCtx.pTab==pTab );
+
+  if( SQLITE_OK!=rc ){
+    if( zErr==0 ){
+      *pzErr = sqlite3MPrintf(db, "vtable constructor failed: %s", zModuleName);
+    }else {
+      *pzErr = sqlite3MPrintf(db, "%s", zErr);
+      sqlite3_free(zErr);
+    }
+    sqlite3DbFree(db, pVTable);
+  }else if( ALWAYS(pVTable->pVtab) ){
+    /* Justification of ALWAYS():  A correct vtab constructor must allocate
+    ** the sqlite3_vtab object if successful.  */
+    memset(pVTable->pVtab, 0, sizeof(pVTable->pVtab[0]));
+    pVTable->pVtab->pModule = pMod->pModule;
+    pVTable->nRef = 1;
+    if( sCtx.bDeclared==0 ){
+      const char *zFormat = "vtable constructor did not declare schema: %s";
+      *pzErr = sqlite3MPrintf(db, zFormat, pTab->zName);
+      sqlite3VtabUnlock(pVTable);
+      rc = SQLITE_ERROR;
+    }else{
+      int iCol;
+      u8 oooHidden = 0;
+      /* If everything went according to plan, link the new VTable structure
+      ** into the linked list headed by pTab->pVTable. Then loop through the 
+      ** columns of the table to see if any of them contain the token "hidden".
+      ** If so, set the Column COLFLAG_HIDDEN flag and remove the token from
+      ** the type string.  */
+      pVTable->pNext = pTab->pVTable;
+      pTab->pVTable = pVTable;
+
+      for(iCol=0; iCol<pTab->nCol; iCol++){
+        char *zType = sqlite3ColumnType(&pTab->aCol[iCol], "");
+        int nType;
+        int i = 0;
+        nType = sqlite3Strlen30(zType);
+        for(i=0; i<nType; i++){
+          if( 0==sqlite3StrNICmp("hidden", &zType[i], 6)
+           && (i==0 || zType[i-1]==' ')
+           && (zType[i+6]=='\0' || zType[i+6]==' ')
+          ){
+            break;
+          }
+        }
+        if( i<nType ){
+          int j;
+          int nDel = 6 + (zType[i+6] ? 1 : 0);
+          for(j=i; (j+nDel)<=nType; j++){
+            zType[j] = zType[j+nDel];
+          }
+          if( zType[i]=='\0' && i>0 ){
+            assert(zType[i-1]==' ');
+            zType[i-1] = '\0';
+          }
+          pTab->aCol[iCol].colFlags |= COLFLAG_HIDDEN;
+          oooHidden = TF_OOOHidden;
+        }else{
+          pTab->tabFlags |= oooHidden;
+        }
+      }
+    }
+  }
+
+  sqlite3DbFree(db, zModuleName);
+  return rc;
+}
+
+/*
+** This function is invoked by the parser to call the xConnect() method
+** of the virtual table pTab. If an error occurs, an error code is returned 
+** and an error left in pParse.
+**
+** This call is a no-op if table pTab is not a virtual table.
+*/
+SQLITE_PRIVATE int sqlite3VtabCallConnect(Parse *pParse, Table *pTab){
+  sqlite3 *db = pParse->db;
+  const char *zMod;
+  Module *pMod;
+  int rc;
+
+  assert( pTab );
+  if( (pTab->tabFlags & TF_Virtual)==0 || sqlite3GetVTable(db, pTab) ){
+    return SQLITE_OK;
+  }
+
+  /* Locate the required virtual table module */
+  zMod = pTab->azModuleArg[0];
+  pMod = (Module*)sqlite3HashFind(&db->aModule, zMod);
+
+  if( !pMod ){
+    const char *zModule = pTab->azModuleArg[0];
+    sqlite3ErrorMsg(pParse, "no such module: %s", zModule);
+    rc = SQLITE_ERROR;
+  }else{
+    char *zErr = 0;
+    rc = vtabCallConstructor(db, pTab, pMod, pMod->pModule->xConnect, &zErr);
+    if( rc!=SQLITE_OK ){
+      sqlite3ErrorMsg(pParse, "%s", zErr);
+    }
+    sqlite3DbFree(db, zErr);
+  }
+
+  return rc;
+}
+/*
+** Grow the db->aVTrans[] array so that there is room for at least one
+** more v-table. Return SQLITE_NOMEM if a malloc fails, or SQLITE_OK otherwise.
+*/
+static int growVTrans(sqlite3 *db){
+  const int ARRAY_INCR = 5;
+
+  /* Grow the sqlite3.aVTrans array if required */
+  if( (db->nVTrans%ARRAY_INCR)==0 ){
+    VTable **aVTrans;
+    int nBytes = sizeof(sqlite3_vtab *) * (db->nVTrans + ARRAY_INCR);
+    aVTrans = sqlite3DbRealloc(db, (void *)db->aVTrans, nBytes);
+    if( !aVTrans ){
+      return SQLITE_NOMEM_BKPT;
+    }
+    memset(&aVTrans[db->nVTrans], 0, sizeof(sqlite3_vtab *)*ARRAY_INCR);
+    db->aVTrans = aVTrans;
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Add the virtual table pVTab to the array sqlite3.aVTrans[]. Space should
+** have already been reserved using growVTrans().
+*/
+static void addToVTrans(sqlite3 *db, VTable *pVTab){
+  /* Add pVtab to the end of sqlite3.aVTrans */
+  db->aVTrans[db->nVTrans++] = pVTab;
+  sqlite3VtabLock(pVTab);
+}
+
+/*
+** This function is invoked by the vdbe to call the xCreate method
+** of the virtual table named zTab in database iDb. 
+**
+** If an error occurs, *pzErr is set to point to an English language
+** description of the error and an SQLITE_XXX error code is returned.
+** In this case the caller must call sqlite3DbFree(db, ) on *pzErr.
+*/
+SQLITE_PRIVATE int sqlite3VtabCallCreate(sqlite3 *db, int iDb, const char *zTab, char **pzErr){
+  int rc = SQLITE_OK;
+  Table *pTab;
+  Module *pMod;
+  const char *zMod;
+
+  pTab = sqlite3FindTable(db, zTab, db->aDb[iDb].zDbSName);
+  assert( pTab && (pTab->tabFlags & TF_Virtual)!=0 && !pTab->pVTable );
+
+  /* Locate the required virtual table module */
+  zMod = pTab->azModuleArg[0];
+  pMod = (Module*)sqlite3HashFind(&db->aModule, zMod);
+
+  /* If the module has been registered and includes a Create method, 
+  ** invoke it now. If the module has not been registered, return an 
+  ** error. Otherwise, do nothing.
+  */
+  if( pMod==0 || pMod->pModule->xCreate==0 || pMod->pModule->xDestroy==0 ){
+    *pzErr = sqlite3MPrintf(db, "no such module: %s", zMod);
+    rc = SQLITE_ERROR;
+  }else{
+    rc = vtabCallConstructor(db, pTab, pMod, pMod->pModule->xCreate, pzErr);
+  }
+
+  /* Justification of ALWAYS():  The xConstructor method is required to
+  ** create a valid sqlite3_vtab if it returns SQLITE_OK. */
+  if( rc==SQLITE_OK && ALWAYS(sqlite3GetVTable(db, pTab)) ){
+    rc = growVTrans(db);
+    if( rc==SQLITE_OK ){
+      addToVTrans(db, sqlite3GetVTable(db, pTab));
+    }
+  }
+
+  return rc;
+}
+
+/*
+** This function is used to set the schema of a virtual table.  It is only
+** valid to call this function from within the xCreate() or xConnect() of a
+** virtual table module.
+*/
+SQLITE_API int sqlite3_declare_vtab(sqlite3 *db, const char *zCreateTable){
+  VtabCtx *pCtx;
+  Parse *pParse;
+  int rc = SQLITE_OK;
+  Table *pTab;
+  char *zErr = 0;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) || zCreateTable==0 ){
+    return SQLITE_MISUSE_BKPT;
+  }
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  pCtx = db->pVtabCtx;
+  if( !pCtx || pCtx->bDeclared ){
+    sqlite3Error(db, SQLITE_MISUSE);
+    sqlite3_mutex_leave(db->mutex);
+    return SQLITE_MISUSE_BKPT;
+  }
+  pTab = pCtx->pTab;
+  assert( (pTab->tabFlags & TF_Virtual)!=0 );
+
+  pParse = sqlite3StackAllocZero(db, sizeof(*pParse));
+  if( pParse==0 ){
+    rc = SQLITE_NOMEM_BKPT;
+  }else{
+    pParse->declareVtab = 1;
+    pParse->db = db;
+    pParse->nQueryLoop = 1;
+  
+    if( SQLITE_OK==sqlite3RunParser(pParse, zCreateTable, &zErr) 
+     && pParse->pNewTable
+     && !db->mallocFailed
+     && !pParse->pNewTable->pSelect
+     && (pParse->pNewTable->tabFlags & TF_Virtual)==0
+    ){
+      if( !pTab->aCol ){
+        Table *pNew = pParse->pNewTable;
+        Index *pIdx;
+        pTab->aCol = pNew->aCol;
+        pTab->nCol = pNew->nCol;
+        pTab->tabFlags |= pNew->tabFlags & (TF_WithoutRowid|TF_NoVisibleRowid);
+        pNew->nCol = 0;
+        pNew->aCol = 0;
+        assert( pTab->pIndex==0 );
+        if( !HasRowid(pNew) && pCtx->pVTable->pMod->pModule->xUpdate!=0 ){
+          rc = SQLITE_ERROR;
+        }
+        pIdx = pNew->pIndex;
+        if( pIdx ){
+          assert( pIdx->pNext==0 );
+          pTab->pIndex = pIdx;
+          pNew->pIndex = 0;
+          pIdx->pTable = pTab;
+        }
+      }
+      pCtx->bDeclared = 1;
+    }else{
+      sqlite3ErrorWithMsg(db, SQLITE_ERROR, (zErr ? "%s" : 0), zErr);
+      sqlite3DbFree(db, zErr);
+      rc = SQLITE_ERROR;
+    }
+    pParse->declareVtab = 0;
+  
+    if( pParse->pVdbe ){
+      sqlite3VdbeFinalize(pParse->pVdbe);
+    }
+    sqlite3DeleteTable(db, pParse->pNewTable);
+    sqlite3ParserReset(pParse);
+    sqlite3StackFree(db, pParse);
+  }
+
+  assert( (rc&0xff)==rc );
+  rc = sqlite3ApiExit(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+/*
+** This function is invoked by the vdbe to call the xDestroy method
+** of the virtual table named zTab in database iDb. This occurs
+** when a DROP TABLE is mentioned.
+**
+** This call is a no-op if zTab is not a virtual table.
+*/
+SQLITE_PRIVATE int sqlite3VtabCallDestroy(sqlite3 *db, int iDb, const char *zTab){
+  int rc = SQLITE_OK;
+  Table *pTab;
+
+  pTab = sqlite3FindTable(db, zTab, db->aDb[iDb].zDbSName);
+  if( pTab!=0 && ALWAYS(pTab->pVTable!=0) ){
+    VTable *p;
+    int (*xDestroy)(sqlite3_vtab *);
+    for(p=pTab->pVTable; p; p=p->pNext){
+      assert( p->pVtab );
+      if( p->pVtab->nRef>0 ){
+        return SQLITE_LOCKED;
+      }
+    }
+    p = vtabDisconnectAll(db, pTab);
+    xDestroy = p->pMod->pModule->xDestroy;
+    assert( xDestroy!=0 );  /* Checked before the virtual table is created */
+    rc = xDestroy(p->pVtab);
+    /* Remove the sqlite3_vtab* from the aVTrans[] array, if applicable */
+    if( rc==SQLITE_OK ){
+      assert( pTab->pVTable==p && p->pNext==0 );
+      p->pVtab = 0;
+      pTab->pVTable = 0;
+      sqlite3VtabUnlock(p);
+    }
+  }
+
+  return rc;
+}
+
+/*
+** This function invokes either the xRollback or xCommit method
+** of each of the virtual tables in the sqlite3.aVTrans array. The method
+** called is identified by the second argument, "offset", which is
+** the offset of the method to call in the sqlite3_module structure.
+**
+** The array is cleared after invoking the callbacks. 
+*/
+static void callFinaliser(sqlite3 *db, int offset){
+  int i;
+  if( db->aVTrans ){
+    VTable **aVTrans = db->aVTrans;
+    db->aVTrans = 0;
+    for(i=0; i<db->nVTrans; i++){
+      VTable *pVTab = aVTrans[i];
+      sqlite3_vtab *p = pVTab->pVtab;
+      if( p ){
+        int (*x)(sqlite3_vtab *);
+        x = *(int (**)(sqlite3_vtab *))((char *)p->pModule + offset);
+        if( x ) x(p);
+      }
+      pVTab->iSavepoint = 0;
+      sqlite3VtabUnlock(pVTab);
+    }
+    sqlite3DbFree(db, aVTrans);
+    db->nVTrans = 0;
+  }
+}
+
+/*
+** Invoke the xSync method of all virtual tables in the sqlite3.aVTrans
+** array. Return the error code for the first error that occurs, or
+** SQLITE_OK if all xSync operations are successful.
+**
+** If an error message is available, leave it in p->zErrMsg.
+*/
+SQLITE_PRIVATE int sqlite3VtabSync(sqlite3 *db, Vdbe *p){
+  int i;
+  int rc = SQLITE_OK;
+  VTable **aVTrans = db->aVTrans;
+
+  db->aVTrans = 0;
+  for(i=0; rc==SQLITE_OK && i<db->nVTrans; i++){
+    int (*x)(sqlite3_vtab *);
+    sqlite3_vtab *pVtab = aVTrans[i]->pVtab;
+    if( pVtab && (x = pVtab->pModule->xSync)!=0 ){
+      rc = x(pVtab);
+      sqlite3VtabImportErrmsg(p, pVtab);
+    }
+  }
+  db->aVTrans = aVTrans;
+  return rc;
+}
+
+/*
+** Invoke the xRollback method of all virtual tables in the 
+** sqlite3.aVTrans array. Then clear the array itself.
+*/
+SQLITE_PRIVATE int sqlite3VtabRollback(sqlite3 *db){
+  callFinaliser(db, offsetof(sqlite3_module,xRollback));
+  return SQLITE_OK;
+}
+
+/*
+** Invoke the xCommit method of all virtual tables in the 
+** sqlite3.aVTrans array. Then clear the array itself.
+*/
+SQLITE_PRIVATE int sqlite3VtabCommit(sqlite3 *db){
+  callFinaliser(db, offsetof(sqlite3_module,xCommit));
+  return SQLITE_OK;
+}
+
+/*
+** If the virtual table pVtab supports the transaction interface
+** (xBegin/xRollback/xCommit and optionally xSync) and a transaction is
+** not currently open, invoke the xBegin method now.
+**
+** If the xBegin call is successful, place the sqlite3_vtab pointer
+** in the sqlite3.aVTrans array.
+*/
+SQLITE_PRIVATE int sqlite3VtabBegin(sqlite3 *db, VTable *pVTab){
+  int rc = SQLITE_OK;
+  const sqlite3_module *pModule;
+
+  /* Special case: If db->aVTrans is NULL and db->nVTrans is greater
+  ** than zero, then this function is being called from within a
+  ** virtual module xSync() callback. It is illegal to write to 
+  ** virtual module tables in this case, so return SQLITE_LOCKED.
+  */
+  if( sqlite3VtabInSync(db) ){
+    return SQLITE_LOCKED;
+  }
+  if( !pVTab ){
+    return SQLITE_OK;
+  } 
+  pModule = pVTab->pVtab->pModule;
+
+  if( pModule->xBegin ){
+    int i;
+
+    /* If pVtab is already in the aVTrans array, return early */
+    for(i=0; i<db->nVTrans; i++){
+      if( db->aVTrans[i]==pVTab ){
+        return SQLITE_OK;
+      }
+    }
+
+    /* Invoke the xBegin method. If successful, add the vtab to the 
+    ** sqlite3.aVTrans[] array. */
+    rc = growVTrans(db);
+    if( rc==SQLITE_OK ){
+      rc = pModule->xBegin(pVTab->pVtab);
+      if( rc==SQLITE_OK ){
+        int iSvpt = db->nStatement + db->nSavepoint;
+        addToVTrans(db, pVTab);
+        if( iSvpt && pModule->xSavepoint ){
+          pVTab->iSavepoint = iSvpt;
+          rc = pModule->xSavepoint(pVTab->pVtab, iSvpt-1);
+        }
+      }
+    }
+  }
+  return rc;
+}
+
+/*
+** Invoke either the xSavepoint, xRollbackTo or xRelease method of all
+** virtual tables that currently have an open transaction. Pass iSavepoint
+** as the second argument to the virtual table method invoked.
+**
+** If op is SAVEPOINT_BEGIN, the xSavepoint method is invoked. If it is
+** SAVEPOINT_ROLLBACK, the xRollbackTo method. Otherwise, if op is 
+** SAVEPOINT_RELEASE, then the xRelease method of each virtual table with
+** an open transaction is invoked.
+**
+** If any virtual table method returns an error code other than SQLITE_OK, 
+** processing is abandoned and the error returned to the caller of this
+** function immediately. If all calls to virtual table methods are successful,
+** SQLITE_OK is returned.
+*/
+SQLITE_PRIVATE int sqlite3VtabSavepoint(sqlite3 *db, int op, int iSavepoint){
+  int rc = SQLITE_OK;
+
+  assert( op==SAVEPOINT_RELEASE||op==SAVEPOINT_ROLLBACK||op==SAVEPOINT_BEGIN );
+  assert( iSavepoint>=-1 );
+  if( db->aVTrans ){
+    int i;
+    for(i=0; rc==SQLITE_OK && i<db->nVTrans; i++){
+      VTable *pVTab = db->aVTrans[i];
+      const sqlite3_module *pMod = pVTab->pMod->pModule;
+      if( pVTab->pVtab && pMod->iVersion>=2 ){
+        int (*xMethod)(sqlite3_vtab *, int);
+        switch( op ){
+          case SAVEPOINT_BEGIN:
+            xMethod = pMod->xSavepoint;
+            pVTab->iSavepoint = iSavepoint+1;
+            break;
+          case SAVEPOINT_ROLLBACK:
+            xMethod = pMod->xRollbackTo;
+            break;
+          default:
+            xMethod = pMod->xRelease;
+            break;
+        }
+        if( xMethod && pVTab->iSavepoint>iSavepoint ){
+          rc = xMethod(pVTab->pVtab, iSavepoint);
+        }
+      }
+    }
+  }
+  return rc;
+}
+
+/*
+** The first parameter (pDef) is a function implementation.  The
+** second parameter (pExpr) is the first argument to this function.
+** If pExpr is a column in a virtual table, then let the virtual
+** table implementation have an opportunity to overload the function.
+**
+** This routine is used to allow virtual table implementations to
+** overload MATCH, LIKE, GLOB, and REGEXP operators.
+**
+** Return either the pDef argument (indicating no change) or a 
+** new FuncDef structure that is marked as ephemeral using the
+** SQLITE_FUNC_EPHEM flag.
+*/
+SQLITE_PRIVATE FuncDef *sqlite3VtabOverloadFunction(
+  sqlite3 *db,    /* Database connection for reporting malloc problems */
+  FuncDef *pDef,  /* Function to possibly overload */
+  int nArg,       /* Number of arguments to the function */
+  Expr *pExpr     /* First argument to the function */
+){
+  Table *pTab;
+  sqlite3_vtab *pVtab;
+  sqlite3_module *pMod;
+  void (*xSFunc)(sqlite3_context*,int,sqlite3_value**) = 0;
+  void *pArg = 0;
+  FuncDef *pNew;
+  int rc = 0;
+  char *zLowerName;
+  unsigned char *z;
+
+
+  /* Check to see the left operand is a column in a virtual table */
+  if( NEVER(pExpr==0) ) return pDef;
+  if( pExpr->op!=TK_COLUMN ) return pDef;
+  pTab = pExpr->pTab;
+  if( NEVER(pTab==0) ) return pDef;
+  if( (pTab->tabFlags & TF_Virtual)==0 ) return pDef;
+  pVtab = sqlite3GetVTable(db, pTab)->pVtab;
+  assert( pVtab!=0 );
+  assert( pVtab->pModule!=0 );
+  pMod = (sqlite3_module *)pVtab->pModule;
+  if( pMod->xFindFunction==0 ) return pDef;
+ 
+  /* Call the xFindFunction method on the virtual table implementation
+  ** to see if the implementation wants to overload this function 
+  */
+  zLowerName = sqlite3DbStrDup(db, pDef->zName);
+  if( zLowerName ){
+    for(z=(unsigned char*)zLowerName; *z; z++){
+      *z = sqlite3UpperToLower[*z];
+    }
+    rc = pMod->xFindFunction(pVtab, nArg, zLowerName, &xSFunc, &pArg);
+    sqlite3DbFree(db, zLowerName);
+  }
+  if( rc==0 ){
+    return pDef;
+  }
+
+  /* Create a new ephemeral function definition for the overloaded
+  ** function */
+  pNew = sqlite3DbMallocZero(db, sizeof(*pNew)
+                             + sqlite3Strlen30(pDef->zName) + 1);
+  if( pNew==0 ){
+    return pDef;
+  }
+  *pNew = *pDef;
+  pNew->zName = (const char*)&pNew[1];
+  memcpy((char*)&pNew[1], pDef->zName, sqlite3Strlen30(pDef->zName)+1);
+  pNew->xSFunc = xSFunc;
+  pNew->pUserData = pArg;
+  pNew->funcFlags |= SQLITE_FUNC_EPHEM;
+  return pNew;
+}
+
+/*
+** Make sure virtual table pTab is contained in the pParse->apVirtualLock[]
+** array so that an OP_VBegin will get generated for it.  Add pTab to the
+** array if it is missing.  If pTab is already in the array, this routine
+** is a no-op.
+*/
+SQLITE_PRIVATE void sqlite3VtabMakeWritable(Parse *pParse, Table *pTab){
+  Parse *pToplevel = sqlite3ParseToplevel(pParse);
+  int i, n;
+  Table **apVtabLock;
+
+  assert( IsVirtual(pTab) );
+  for(i=0; i<pToplevel->nVtabLock; i++){
+    if( pTab==pToplevel->apVtabLock[i] ) return;
+  }
+  n = (pToplevel->nVtabLock+1)*sizeof(pToplevel->apVtabLock[0]);
+  apVtabLock = sqlite3_realloc64(pToplevel->apVtabLock, n);
+  if( apVtabLock ){
+    pToplevel->apVtabLock = apVtabLock;
+    pToplevel->apVtabLock[pToplevel->nVtabLock++] = pTab;
+  }else{
+    sqlite3OomFault(pToplevel->db);
+  }
+}
+
+/*
+** Check to see if virtual table module pMod can be have an eponymous
+** virtual table instance.  If it can, create one if one does not already
+** exist. Return non-zero if the eponymous virtual table instance exists
+** when this routine returns, and return zero if it does not exist.
+**
+** An eponymous virtual table instance is one that is named after its
+** module, and more importantly, does not require a CREATE VIRTUAL TABLE
+** statement in order to come into existance.  Eponymous virtual table
+** instances always exist.  They cannot be DROP-ed.
+**
+** Any virtual table module for which xConnect and xCreate are the same
+** method can have an eponymous virtual table instance.
+*/
+SQLITE_PRIVATE int sqlite3VtabEponymousTableInit(Parse *pParse, Module *pMod){
+  const sqlite3_module *pModule = pMod->pModule;
+  Table *pTab;
+  char *zErr = 0;
+  int rc;
+  sqlite3 *db = pParse->db;
+  if( pMod->pEpoTab ) return 1;
+  if( pModule->xCreate!=0 && pModule->xCreate!=pModule->xConnect ) return 0;
+  pTab = sqlite3DbMallocZero(db, sizeof(Table));
+  if( pTab==0 ) return 0;
+  pTab->zName = sqlite3DbStrDup(db, pMod->zName);
+  if( pTab->zName==0 ){
+    sqlite3DbFree(db, pTab);
+    return 0;
+  }
+  pMod->pEpoTab = pTab;
+  pTab->nRef = 1;
+  pTab->pSchema = db->aDb[0].pSchema;
+  pTab->tabFlags |= TF_Virtual;
+  pTab->nModuleArg = 0;
+  pTab->iPKey = -1;
+  addModuleArgument(db, pTab, sqlite3DbStrDup(db, pTab->zName));
+  addModuleArgument(db, pTab, 0);
+  addModuleArgument(db, pTab, sqlite3DbStrDup(db, pTab->zName));
+  rc = vtabCallConstructor(db, pTab, pMod, pModule->xConnect, &zErr);
+  if( rc ){
+    sqlite3ErrorMsg(pParse, "%s", zErr);
+    sqlite3DbFree(db, zErr);
+    sqlite3VtabEponymousTableClear(db, pMod);
+    return 0;
+  }
+  return 1;
+}
+
+/*
+** Erase the eponymous virtual table instance associated with
+** virtual table module pMod, if it exists.
+*/
+SQLITE_PRIVATE void sqlite3VtabEponymousTableClear(sqlite3 *db, Module *pMod){
+  Table *pTab = pMod->pEpoTab;
+  if( pTab!=0 ){
+    /* Mark the table as Ephemeral prior to deleting it, so that the
+    ** sqlite3DeleteTable() routine will know that it is not stored in 
+    ** the schema. */
+    pTab->tabFlags |= TF_Ephemeral;
+    sqlite3DeleteTable(db, pTab);
+    pMod->pEpoTab = 0;
+  }
+}
+
+/*
+** Return the ON CONFLICT resolution mode in effect for the virtual
+** table update operation currently in progress.
+**
+** The results of this routine are undefined unless it is called from
+** within an xUpdate method.
+*/
+SQLITE_API int sqlite3_vtab_on_conflict(sqlite3 *db){
+  static const unsigned char aMap[] = { 
+    SQLITE_ROLLBACK, SQLITE_ABORT, SQLITE_FAIL, SQLITE_IGNORE, SQLITE_REPLACE 
+  };
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
+#endif
+  assert( OE_Rollback==1 && OE_Abort==2 && OE_Fail==3 );
+  assert( OE_Ignore==4 && OE_Replace==5 );
+  assert( db->vtabOnConflict>=1 && db->vtabOnConflict<=5 );
+  return (int)aMap[db->vtabOnConflict-1];
+}
+
+/*
+** Call from within the xCreate() or xConnect() methods to provide 
+** the SQLite core with additional information about the behavior
+** of the virtual table being implemented.
+*/
+SQLITE_API int sqlite3_vtab_config(sqlite3 *db, int op, ...){
+  va_list ap;
+  int rc = SQLITE_OK;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  va_start(ap, op);
+  switch( op ){
+    case SQLITE_VTAB_CONSTRAINT_SUPPORT: {
+      VtabCtx *p = db->pVtabCtx;
+      if( !p ){
+        rc = SQLITE_MISUSE_BKPT;
+      }else{
+        assert( p->pTab==0 || (p->pTab->tabFlags & TF_Virtual)!=0 );
+        p->pVTable->bConstraint = (u8)va_arg(ap, int);
+      }
+      break;
+    }
+    default:
+      rc = SQLITE_MISUSE_BKPT;
+      break;
+  }
+  va_end(ap);
+
+  if( rc!=SQLITE_OK ) sqlite3Error(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+/************** End of vtab.c ************************************************/
+/************** Begin file wherecode.c ***************************************/
+/*
+** 2015-06-06
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This module contains C code that generates VDBE code used to process
+** the WHERE clause of SQL statements.
+**
+** This file was split off from where.c on 2015-06-06 in order to reduce the
+** size of where.c and make it easier to edit.  This file contains the routines
+** that actually generate the bulk of the WHERE loop code.  The original where.c
+** file retains the code that does query planning and analysis.
+*/
+/* #include "sqliteInt.h" */
+/************** Include whereInt.h in the middle of wherecode.c **************/
+/************** Begin file whereInt.h ****************************************/
+/*
+** 2013-11-12
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains structure and macro definitions for the query
+** planner logic in "where.c".  These definitions are broken out into
+** a separate source file for easier editing.
+*/
+
+/*
+** Trace output macros
+*/
+#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
+/***/ int sqlite3WhereTrace;
+#endif
+#if defined(SQLITE_DEBUG) \
+    && (defined(SQLITE_TEST) || defined(SQLITE_ENABLE_WHERETRACE))
+# define WHERETRACE(K,X)  if(sqlite3WhereTrace&(K)) sqlite3DebugPrintf X
+# define WHERETRACE_ENABLED 1
+#else
+# define WHERETRACE(K,X)
+#endif
+
+/* Forward references
+*/
+typedef struct WhereClause WhereClause;
+typedef struct WhereMaskSet WhereMaskSet;
+typedef struct WhereOrInfo WhereOrInfo;
+typedef struct WhereAndInfo WhereAndInfo;
+typedef struct WhereLevel WhereLevel;
+typedef struct WhereLoop WhereLoop;
+typedef struct WherePath WherePath;
+typedef struct WhereTerm WhereTerm;
+typedef struct WhereLoopBuilder WhereLoopBuilder;
+typedef struct WhereScan WhereScan;
+typedef struct WhereOrCost WhereOrCost;
+typedef struct WhereOrSet WhereOrSet;
+
+/*
+** This object contains information needed to implement a single nested
+** loop in WHERE clause.
+**
+** Contrast this object with WhereLoop.  This object describes the
+** implementation of the loop.  WhereLoop describes the algorithm.
+** This object contains a pointer to the WhereLoop algorithm as one of
+** its elements.
+**
+** The WhereInfo object contains a single instance of this object for
+** each term in the FROM clause (which is to say, for each of the
+** nested loops as implemented).  The order of WhereLevel objects determines
+** the loop nested order, with WhereInfo.a[0] being the outer loop and
+** WhereInfo.a[WhereInfo.nLevel-1] being the inner loop.
+*/
+struct WhereLevel {
+  int iLeftJoin;        /* Memory cell used to implement LEFT OUTER JOIN */
+  int iTabCur;          /* The VDBE cursor used to access the table */
+  int iIdxCur;          /* The VDBE cursor used to access pIdx */
+  int addrBrk;          /* Jump here to break out of the loop */
+  int addrNxt;          /* Jump here to start the next IN combination */
+  int addrSkip;         /* Jump here for next iteration of skip-scan */
+  int addrCont;         /* Jump here to continue with the next loop cycle */
+  int addrFirst;        /* First instruction of interior of the loop */
+  int addrBody;         /* Beginning of the body of this loop */
+#ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
+  u32 iLikeRepCntr;     /* LIKE range processing counter register (times 2) */
+  int addrLikeRep;      /* LIKE range processing address */
+#endif
+  u8 iFrom;             /* Which entry in the FROM clause */
+  u8 op, p3, p5;        /* Opcode, P3 & P5 of the opcode that ends the loop */
+  int p1, p2;           /* Operands of the opcode used to ends the loop */
+  union {               /* Information that depends on pWLoop->wsFlags */
+    struct {
+      int nIn;              /* Number of entries in aInLoop[] */
+      struct InLoop {
+        int iCur;              /* The VDBE cursor used by this IN operator */
+        int addrInTop;         /* Top of the IN loop */
+        u8 eEndLoopOp;         /* IN Loop terminator. OP_Next or OP_Prev */
+      } *aInLoop;           /* Information about each nested IN operator */
+    } in;                 /* Used when pWLoop->wsFlags&WHERE_IN_ABLE */
+    Index *pCovidx;       /* Possible covering index for WHERE_MULTI_OR */
+  } u;
+  struct WhereLoop *pWLoop;  /* The selected WhereLoop object */
+  Bitmask notReady;          /* FROM entries not usable at this level */
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+  int addrVisit;        /* Address at which row is visited */
+#endif
+};
+
+/*
+** Each instance of this object represents an algorithm for evaluating one
+** term of a join.  Every term of the FROM clause will have at least
+** one corresponding WhereLoop object (unless INDEXED BY constraints
+** prevent a query solution - which is an error) and many terms of the
+** FROM clause will have multiple WhereLoop objects, each describing a
+** potential way of implementing that FROM-clause term, together with
+** dependencies and cost estimates for using the chosen algorithm.
+**
+** Query planning consists of building up a collection of these WhereLoop
+** objects, then computing a particular sequence of WhereLoop objects, with
+** one WhereLoop object per FROM clause term, that satisfy all dependencies
+** and that minimize the overall cost.
+*/
+struct WhereLoop {
+  Bitmask prereq;       /* Bitmask of other loops that must run first */
+  Bitmask maskSelf;     /* Bitmask identifying table iTab */
+#ifdef SQLITE_DEBUG
+  char cId;             /* Symbolic ID of this loop for debugging use */
+#endif
+  u8 iTab;              /* Position in FROM clause of table for this loop */
+  u8 iSortIdx;          /* Sorting index number.  0==None */
+  LogEst rSetup;        /* One-time setup cost (ex: create transient index) */
+  LogEst rRun;          /* Cost of running each loop */
+  LogEst nOut;          /* Estimated number of output rows */
+  union {
+    struct {               /* Information for internal btree tables */
+      u16 nEq;               /* Number of equality constraints */
+      u16 nBtm;              /* Size of BTM vector */
+      u16 nTop;              /* Size of TOP vector */
+      Index *pIndex;         /* Index used, or NULL */
+    } btree;
+    struct {               /* Information for virtual tables */
+      int idxNum;            /* Index number */
+      u8 needFree;           /* True if sqlite3_free(idxStr) is needed */
+      i8 isOrdered;          /* True if satisfies ORDER BY */
+      u16 omitMask;          /* Terms that may be omitted */
+      char *idxStr;          /* Index identifier string */
+    } vtab;
+  } u;
+  u32 wsFlags;          /* WHERE_* flags describing the plan */
+  u16 nLTerm;           /* Number of entries in aLTerm[] */
+  u16 nSkip;            /* Number of NULL aLTerm[] entries */
+  /**** whereLoopXfer() copies fields above ***********************/
+# define WHERE_LOOP_XFER_SZ offsetof(WhereLoop,nLSlot)
+  u16 nLSlot;           /* Number of slots allocated for aLTerm[] */
+  WhereTerm **aLTerm;   /* WhereTerms used */
+  WhereLoop *pNextLoop; /* Next WhereLoop object in the WhereClause */
+  WhereTerm *aLTermSpace[3];  /* Initial aLTerm[] space */
+};
+
+/* This object holds the prerequisites and the cost of running a
+** subquery on one operand of an OR operator in the WHERE clause.
+** See WhereOrSet for additional information 
+*/
+struct WhereOrCost {
+  Bitmask prereq;     /* Prerequisites */
+  LogEst rRun;        /* Cost of running this subquery */
+  LogEst nOut;        /* Number of outputs for this subquery */
+};
+
+/* The WhereOrSet object holds a set of possible WhereOrCosts that
+** correspond to the subquery(s) of OR-clause processing.  Only the
+** best N_OR_COST elements are retained.
+*/
+#define N_OR_COST 3
+struct WhereOrSet {
+  u16 n;                      /* Number of valid a[] entries */
+  WhereOrCost a[N_OR_COST];   /* Set of best costs */
+};
+
+/*
+** Each instance of this object holds a sequence of WhereLoop objects
+** that implement some or all of a query plan.
+**
+** Think of each WhereLoop object as a node in a graph with arcs
+** showing dependencies and costs for travelling between nodes.  (That is
+** not a completely accurate description because WhereLoop costs are a
+** vector, not a scalar, and because dependencies are many-to-one, not
+** one-to-one as are graph nodes.  But it is a useful visualization aid.)
+** Then a WherePath object is a path through the graph that visits some
+** or all of the WhereLoop objects once.
+**
+** The "solver" works by creating the N best WherePath objects of length
+** 1.  Then using those as a basis to compute the N best WherePath objects
+** of length 2.  And so forth until the length of WherePaths equals the
+** number of nodes in the FROM clause.  The best (lowest cost) WherePath
+** at the end is the chosen query plan.
+*/
+struct WherePath {
+  Bitmask maskLoop;     /* Bitmask of all WhereLoop objects in this path */
+  Bitmask revLoop;      /* aLoop[]s that should be reversed for ORDER BY */
+  LogEst nRow;          /* Estimated number of rows generated by this path */
+  LogEst rCost;         /* Total cost of this path */
+  LogEst rUnsorted;     /* Total cost of this path ignoring sorting costs */
+  i8 isOrdered;         /* No. of ORDER BY terms satisfied. -1 for unknown */
+  WhereLoop **aLoop;    /* Array of WhereLoop objects implementing this path */
+};
+
+/*
+** The query generator uses an array of instances of this structure to
+** help it analyze the subexpressions of the WHERE clause.  Each WHERE
+** clause subexpression is separated from the others by AND operators,
+** usually, or sometimes subexpressions separated by OR.
+**
+** All WhereTerms are collected into a single WhereClause structure.  
+** The following identity holds:
+**
+**        WhereTerm.pWC->a[WhereTerm.idx] == WhereTerm
+**
+** When a term is of the form:
+**
+**              X <op> <expr>
+**
+** where X is a column name and <op> is one of certain operators,
+** then WhereTerm.leftCursor and WhereTerm.u.leftColumn record the
+** cursor number and column number for X.  WhereTerm.eOperator records
+** the <op> using a bitmask encoding defined by WO_xxx below.  The
+** use of a bitmask encoding for the operator allows us to search
+** quickly for terms that match any of several different operators.
+**
+** A WhereTerm might also be two or more subterms connected by OR:
+**
+**         (t1.X <op> <expr>) OR (t1.Y <op> <expr>) OR ....
+**
+** In this second case, wtFlag has the TERM_ORINFO bit set and eOperator==WO_OR
+** and the WhereTerm.u.pOrInfo field points to auxiliary information that
+** is collected about the OR clause.
+**
+** If a term in the WHERE clause does not match either of the two previous
+** categories, then eOperator==0.  The WhereTerm.pExpr field is still set
+** to the original subexpression content and wtFlags is set up appropriately
+** but no other fields in the WhereTerm object are meaningful.
+**
+** When eOperator!=0, prereqRight and prereqAll record sets of cursor numbers,
+** but they do so indirectly.  A single WhereMaskSet structure translates
+** cursor number into bits and the translated bit is stored in the prereq
+** fields.  The translation is used in order to maximize the number of
+** bits that will fit in a Bitmask.  The VDBE cursor numbers might be
+** spread out over the non-negative integers.  For example, the cursor
+** numbers might be 3, 8, 9, 10, 20, 23, 41, and 45.  The WhereMaskSet
+** translates these sparse cursor numbers into consecutive integers
+** beginning with 0 in order to make the best possible use of the available
+** bits in the Bitmask.  So, in the example above, the cursor numbers
+** would be mapped into integers 0 through 7.
+**
+** The number of terms in a join is limited by the number of bits
+** in prereqRight and prereqAll.  The default is 64 bits, hence SQLite
+** is only able to process joins with 64 or fewer tables.
+*/
+struct WhereTerm {
+  Expr *pExpr;            /* Pointer to the subexpression that is this term */
+  WhereClause *pWC;       /* The clause this term is part of */
+  LogEst truthProb;       /* Probability of truth for this expression */
+  u16 wtFlags;            /* TERM_xxx bit flags.  See below */
+  u16 eOperator;          /* A WO_xx value describing <op> */
+  u8 nChild;              /* Number of children that must disable us */
+  u8 eMatchOp;            /* Op for vtab MATCH/LIKE/GLOB/REGEXP terms */
+  int iParent;            /* Disable pWC->a[iParent] when this term disabled */
+  int leftCursor;         /* Cursor number of X in "X <op> <expr>" */
+  int iField;             /* Field in (?,?,?) IN (SELECT...) vector */
+  union {
+    int leftColumn;         /* Column number of X in "X <op> <expr>" */
+    WhereOrInfo *pOrInfo;   /* Extra information if (eOperator & WO_OR)!=0 */
+    WhereAndInfo *pAndInfo; /* Extra information if (eOperator& WO_AND)!=0 */
+  } u;
+  Bitmask prereqRight;    /* Bitmask of tables used by pExpr->pRight */
+  Bitmask prereqAll;      /* Bitmask of tables referenced by pExpr */
+};
+
+/*
+** Allowed values of WhereTerm.wtFlags
+*/
+#define TERM_DYNAMIC    0x01   /* Need to call sqlite3ExprDelete(db, pExpr) */
+#define TERM_VIRTUAL    0x02   /* Added by the optimizer.  Do not code */
+#define TERM_CODED      0x04   /* This term is already coded */
+#define TERM_COPIED     0x08   /* Has a child */
+#define TERM_ORINFO     0x10   /* Need to free the WhereTerm.u.pOrInfo object */
+#define TERM_ANDINFO    0x20   /* Need to free the WhereTerm.u.pAndInfo obj */
+#define TERM_OR_OK      0x40   /* Used during OR-clause processing */
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+#  define TERM_VNULL    0x80   /* Manufactured x>NULL or x<=NULL term */
+#else
+#  define TERM_VNULL    0x00   /* Disabled if not using stat3 */
+#endif
+#define TERM_LIKEOPT    0x100  /* Virtual terms from the LIKE optimization */
+#define TERM_LIKECOND   0x200  /* Conditionally this LIKE operator term */
+#define TERM_LIKE       0x400  /* The original LIKE operator */
+#define TERM_IS         0x800  /* Term.pExpr is an IS operator */
+
+/*
+** An instance of the WhereScan object is used as an iterator for locating
+** terms in the WHERE clause that are useful to the query planner.
+*/
+struct WhereScan {
+  WhereClause *pOrigWC;      /* Original, innermost WhereClause */
+  WhereClause *pWC;          /* WhereClause currently being scanned */
+  const char *zCollName;     /* Required collating sequence, if not NULL */
+  Expr *pIdxExpr;            /* Search for this index expression */
+  char idxaff;               /* Must match this affinity, if zCollName!=NULL */
+  unsigned char nEquiv;      /* Number of entries in aEquiv[] */
+  unsigned char iEquiv;      /* Next unused slot in aEquiv[] */
+  u32 opMask;                /* Acceptable operators */
+  int k;                     /* Resume scanning at this->pWC->a[this->k] */
+  int aiCur[11];             /* Cursors in the equivalence class */
+  i16 aiColumn[11];          /* Corresponding column number in the eq-class */
+};
+
+/*
+** An instance of the following structure holds all information about a
+** WHERE clause.  Mostly this is a container for one or more WhereTerms.
+**
+** Explanation of pOuter:  For a WHERE clause of the form
+**
+**           a AND ((b AND c) OR (d AND e)) AND f
+**
+** There are separate WhereClause objects for the whole clause and for
+** the subclauses "(b AND c)" and "(d AND e)".  The pOuter field of the
+** subclauses points to the WhereClause object for the whole clause.
+*/
+struct WhereClause {
+  WhereInfo *pWInfo;       /* WHERE clause processing context */
+  WhereClause *pOuter;     /* Outer conjunction */
+  u8 op;                   /* Split operator.  TK_AND or TK_OR */
+  int nTerm;               /* Number of terms */
+  int nSlot;               /* Number of entries in a[] */
+  WhereTerm *a;            /* Each a[] describes a term of the WHERE cluase */
+#if defined(SQLITE_SMALL_STACK)
+  WhereTerm aStatic[1];    /* Initial static space for a[] */
+#else
+  WhereTerm aStatic[8];    /* Initial static space for a[] */
+#endif
+};
+
+/*
+** A WhereTerm with eOperator==WO_OR has its u.pOrInfo pointer set to
+** a dynamically allocated instance of the following structure.
+*/
+struct WhereOrInfo {
+  WhereClause wc;          /* Decomposition into subterms */
+  Bitmask indexable;       /* Bitmask of all indexable tables in the clause */
+};
+
+/*
+** A WhereTerm with eOperator==WO_AND has its u.pAndInfo pointer set to
+** a dynamically allocated instance of the following structure.
+*/
+struct WhereAndInfo {
+  WhereClause wc;          /* The subexpression broken out */
+};
+
+/*
+** An instance of the following structure keeps track of a mapping
+** between VDBE cursor numbers and bits of the bitmasks in WhereTerm.
+**
+** The VDBE cursor numbers are small integers contained in 
+** SrcList_item.iCursor and Expr.iTable fields.  For any given WHERE 
+** clause, the cursor numbers might not begin with 0 and they might
+** contain gaps in the numbering sequence.  But we want to make maximum
+** use of the bits in our bitmasks.  This structure provides a mapping
+** from the sparse cursor numbers into consecutive integers beginning
+** with 0.
+**
+** If WhereMaskSet.ix[A]==B it means that The A-th bit of a Bitmask
+** corresponds VDBE cursor number B.  The A-th bit of a bitmask is 1<<A.
+**
+** For example, if the WHERE clause expression used these VDBE
+** cursors:  4, 5, 8, 29, 57, 73.  Then the  WhereMaskSet structure
+** would map those cursor numbers into bits 0 through 5.
+**
+** Note that the mapping is not necessarily ordered.  In the example
+** above, the mapping might go like this:  4->3, 5->1, 8->2, 29->0,
+** 57->5, 73->4.  Or one of 719 other combinations might be used. It
+** does not really matter.  What is important is that sparse cursor
+** numbers all get mapped into bit numbers that begin with 0 and contain
+** no gaps.
+*/
+struct WhereMaskSet {
+  int n;                        /* Number of assigned cursor values */
+  int ix[BMS];                  /* Cursor assigned to each bit */
+};
+
+/*
+** Initialize a WhereMaskSet object
+*/
+#define initMaskSet(P)  (P)->n=0
+
+/*
+** This object is a convenience wrapper holding all information needed
+** to construct WhereLoop objects for a particular query.
+*/
+struct WhereLoopBuilder {
+  WhereInfo *pWInfo;        /* Information about this WHERE */
+  WhereClause *pWC;         /* WHERE clause terms */
+  ExprList *pOrderBy;       /* ORDER BY clause */
+  WhereLoop *pNew;          /* Template WhereLoop */
+  WhereOrSet *pOrSet;       /* Record best loops here, if not NULL */
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  UnpackedRecord *pRec;     /* Probe for stat4 (if required) */
+  int nRecValid;            /* Number of valid fields currently in pRec */
+#endif
+};
+
+/*
+** The WHERE clause processing routine has two halves.  The
+** first part does the start of the WHERE loop and the second
+** half does the tail of the WHERE loop.  An instance of
+** this structure is returned by the first half and passed
+** into the second half to give some continuity.
+**
+** An instance of this object holds the complete state of the query
+** planner.
+*/
+struct WhereInfo {
+  Parse *pParse;            /* Parsing and code generating context */
+  SrcList *pTabList;        /* List of tables in the join */
+  ExprList *pOrderBy;       /* The ORDER BY clause or NULL */
+  ExprList *pDistinctSet;   /* DISTINCT over all these values */
+  LogEst iLimit;            /* LIMIT if wctrlFlags has WHERE_USE_LIMIT */
+  int aiCurOnePass[2];      /* OP_OpenWrite cursors for the ONEPASS opt */
+  int iContinue;            /* Jump here to continue with next record */
+  int iBreak;               /* Jump here to break out of the loop */
+  int savedNQueryLoop;      /* pParse->nQueryLoop outside the WHERE loop */
+  u16 wctrlFlags;           /* Flags originally passed to sqlite3WhereBegin() */
+  u8 nLevel;                /* Number of nested loop */
+  i8 nOBSat;                /* Number of ORDER BY terms satisfied by indices */
+  u8 sorted;                /* True if really sorted (not just grouped) */
+  u8 eOnePass;              /* ONEPASS_OFF, or _SINGLE, or _MULTI */
+  u8 untestedTerms;         /* Not all WHERE terms resolved by outer loop */
+  u8 eDistinct;             /* One of the WHERE_DISTINCT_* values */
+  u8 bOrderedInnerLoop;     /* True if only the inner-most loop is ordered */
+  int iTop;                 /* The very beginning of the WHERE loop */
+  WhereLoop *pLoops;        /* List of all WhereLoop objects */
+  Bitmask revMask;          /* Mask of ORDER BY terms that need reversing */
+  LogEst nRowOut;           /* Estimated number of output rows */
+  WhereClause sWC;          /* Decomposition of the WHERE clause */
+  WhereMaskSet sMaskSet;    /* Map cursor numbers to bitmasks */
+  WhereLevel a[1];          /* Information about each nest loop in WHERE */
+};
+
+/*
+** Private interfaces - callable only by other where.c routines.
+**
+** where.c:
+*/
+SQLITE_PRIVATE Bitmask sqlite3WhereGetMask(WhereMaskSet*,int);
+#ifdef WHERETRACE_ENABLED
+SQLITE_PRIVATE void sqlite3WhereClausePrint(WhereClause *pWC);
+#endif
+SQLITE_PRIVATE WhereTerm *sqlite3WhereFindTerm(
+  WhereClause *pWC,     /* The WHERE clause to be searched */
+  int iCur,             /* Cursor number of LHS */
+  int iColumn,          /* Column number of LHS */
+  Bitmask notReady,     /* RHS must not overlap with this mask */
+  u32 op,               /* Mask of WO_xx values describing operator */
+  Index *pIdx           /* Must be compatible with this index, if not NULL */
+);
+
+/* wherecode.c: */
+#ifndef SQLITE_OMIT_EXPLAIN
+SQLITE_PRIVATE int sqlite3WhereExplainOneScan(
+  Parse *pParse,                  /* Parse context */
+  SrcList *pTabList,              /* Table list this loop refers to */
+  WhereLevel *pLevel,             /* Scan to write OP_Explain opcode for */
+  int iLevel,                     /* Value for "level" column of output */
+  int iFrom,                      /* Value for "from" column of output */
+  u16 wctrlFlags                  /* Flags passed to sqlite3WhereBegin() */
+);
+#else
+# define sqlite3WhereExplainOneScan(u,v,w,x,y,z) 0
+#endif /* SQLITE_OMIT_EXPLAIN */
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+SQLITE_PRIVATE void sqlite3WhereAddScanStatus(
+  Vdbe *v,                        /* Vdbe to add scanstatus entry to */
+  SrcList *pSrclist,              /* FROM clause pLvl reads data from */
+  WhereLevel *pLvl,               /* Level to add scanstatus() entry for */
+  int addrExplain                 /* Address of OP_Explain (or 0) */
+);
+#else
+# define sqlite3WhereAddScanStatus(a, b, c, d) ((void)d)
+#endif
+SQLITE_PRIVATE Bitmask sqlite3WhereCodeOneLoopStart(
+  WhereInfo *pWInfo,   /* Complete information about the WHERE clause */
+  int iLevel,          /* Which level of pWInfo->a[] should be coded */
+  Bitmask notReady     /* Which tables are currently available */
+);
+
+/* whereexpr.c: */
+SQLITE_PRIVATE void sqlite3WhereClauseInit(WhereClause*,WhereInfo*);
+SQLITE_PRIVATE void sqlite3WhereClauseClear(WhereClause*);
+SQLITE_PRIVATE void sqlite3WhereSplit(WhereClause*,Expr*,u8);
+SQLITE_PRIVATE Bitmask sqlite3WhereExprUsage(WhereMaskSet*, Expr*);
+SQLITE_PRIVATE Bitmask sqlite3WhereExprListUsage(WhereMaskSet*, ExprList*);
+SQLITE_PRIVATE void sqlite3WhereExprAnalyze(SrcList*, WhereClause*);
+SQLITE_PRIVATE void sqlite3WhereTabFuncArgs(Parse*, struct SrcList_item*, WhereClause*);
+
+
+
+
+
+/*
+** Bitmasks for the operators on WhereTerm objects.  These are all
+** operators that are of interest to the query planner.  An
+** OR-ed combination of these values can be used when searching for
+** particular WhereTerms within a WhereClause.
+**
+** Value constraints:
+**     WO_EQ    == SQLITE_INDEX_CONSTRAINT_EQ
+**     WO_LT    == SQLITE_INDEX_CONSTRAINT_LT
+**     WO_LE    == SQLITE_INDEX_CONSTRAINT_LE
+**     WO_GT    == SQLITE_INDEX_CONSTRAINT_GT
+**     WO_GE    == SQLITE_INDEX_CONSTRAINT_GE
+**     WO_MATCH == SQLITE_INDEX_CONSTRAINT_MATCH
+*/
+#define WO_IN     0x0001
+#define WO_EQ     0x0002
+#define WO_LT     (WO_EQ<<(TK_LT-TK_EQ))
+#define WO_LE     (WO_EQ<<(TK_LE-TK_EQ))
+#define WO_GT     (WO_EQ<<(TK_GT-TK_EQ))
+#define WO_GE     (WO_EQ<<(TK_GE-TK_EQ))
+#define WO_MATCH  0x0040
+#define WO_IS     0x0080
+#define WO_ISNULL 0x0100
+#define WO_OR     0x0200       /* Two or more OR-connected terms */
+#define WO_AND    0x0400       /* Two or more AND-connected terms */
+#define WO_EQUIV  0x0800       /* Of the form A==B, both columns */
+#define WO_NOOP   0x1000       /* This term does not restrict search space */
+
+#define WO_ALL    0x1fff       /* Mask of all possible WO_* values */
+#define WO_SINGLE 0x01ff       /* Mask of all non-compound WO_* values */
+
+/*
+** These are definitions of bits in the WhereLoop.wsFlags field.
+** The particular combination of bits in each WhereLoop help to
+** determine the algorithm that WhereLoop represents.
+*/
+#define WHERE_COLUMN_EQ    0x00000001  /* x=EXPR */
+#define WHERE_COLUMN_RANGE 0x00000002  /* x<EXPR and/or x>EXPR */
+#define WHERE_COLUMN_IN    0x00000004  /* x IN (...) */
+#define WHERE_COLUMN_NULL  0x00000008  /* x IS NULL */
+#define WHERE_CONSTRAINT   0x0000000f  /* Any of the WHERE_COLUMN_xxx values */
+#define WHERE_TOP_LIMIT    0x00000010  /* x<EXPR or x<=EXPR constraint */
+#define WHERE_BTM_LIMIT    0x00000020  /* x>EXPR or x>=EXPR constraint */
+#define WHERE_BOTH_LIMIT   0x00000030  /* Both x>EXPR and x<EXPR */
+#define WHERE_IDX_ONLY     0x00000040  /* Use index only - omit table */
+#define WHERE_IPK          0x00000100  /* x is the INTEGER PRIMARY KEY */
+#define WHERE_INDEXED      0x00000200  /* WhereLoop.u.btree.pIndex is valid */
+#define WHERE_VIRTUALTABLE 0x00000400  /* WhereLoop.u.vtab is valid */
+#define WHERE_IN_ABLE      0x00000800  /* Able to support an IN operator */
+#define WHERE_ONEROW       0x00001000  /* Selects no more than one row */
+#define WHERE_MULTI_OR     0x00002000  /* OR using multiple indices */
+#define WHERE_AUTO_INDEX   0x00004000  /* Uses an ephemeral index */
+#define WHERE_SKIPSCAN     0x00008000  /* Uses the skip-scan algorithm */
+#define WHERE_UNQ_WANTED   0x00010000  /* WHERE_ONEROW would have been helpful*/
+#define WHERE_PARTIALIDX   0x00020000  /* The automatic index is partial */
+
+/************** End of whereInt.h ********************************************/
+/************** Continuing where we left off in wherecode.c ******************/
+
+#ifndef SQLITE_OMIT_EXPLAIN
+
+/*
+** Return the name of the i-th column of the pIdx index.
+*/
+static const char *explainIndexColumnName(Index *pIdx, int i){
+  i = pIdx->aiColumn[i];
+  if( i==XN_EXPR ) return "<expr>";
+  if( i==XN_ROWID ) return "rowid";
+  return pIdx->pTable->aCol[i].zName;
+}
+
+/*
+** This routine is a helper for explainIndexRange() below
+**
+** pStr holds the text of an expression that we are building up one term
+** at a time.  This routine adds a new term to the end of the expression.
+** Terms are separated by AND so add the "AND" text for second and subsequent
+** terms only.
+*/
+static void explainAppendTerm(
+  StrAccum *pStr,             /* The text expression being built */
+  Index *pIdx,                /* Index to read column names from */
+  int nTerm,                  /* Number of terms */
+  int iTerm,                  /* Zero-based index of first term. */
+  int bAnd,                   /* Non-zero to append " AND " */
+  const char *zOp             /* Name of the operator */
+){
+  int i;
+
+  assert( nTerm>=1 );
+  if( bAnd ) sqlite3StrAccumAppend(pStr, " AND ", 5);
+
+  if( nTerm>1 ) sqlite3StrAccumAppend(pStr, "(", 1);
+  for(i=0; i<nTerm; i++){
+    if( i ) sqlite3StrAccumAppend(pStr, ",", 1);
+    sqlite3StrAccumAppendAll(pStr, explainIndexColumnName(pIdx, iTerm+i));
+  }
+  if( nTerm>1 ) sqlite3StrAccumAppend(pStr, ")", 1);
+
+  sqlite3StrAccumAppend(pStr, zOp, 1);
+
+  if( nTerm>1 ) sqlite3StrAccumAppend(pStr, "(", 1);
+  for(i=0; i<nTerm; i++){
+    if( i ) sqlite3StrAccumAppend(pStr, ",", 1);
+    sqlite3StrAccumAppend(pStr, "?", 1);
+  }
+  if( nTerm>1 ) sqlite3StrAccumAppend(pStr, ")", 1);
+}
+
+/*
+** Argument pLevel describes a strategy for scanning table pTab. This 
+** function appends text to pStr that describes the subset of table
+** rows scanned by the strategy in the form of an SQL expression.
+**
+** For example, if the query:
+**
+**   SELECT * FROM t1 WHERE a=1 AND b>2;
+**
+** is run and there is an index on (a, b), then this function returns a
+** string similar to:
+**
+**   "a=? AND b>?"
+*/
+static void explainIndexRange(StrAccum *pStr, WhereLoop *pLoop){
+  Index *pIndex = pLoop->u.btree.pIndex;
+  u16 nEq = pLoop->u.btree.nEq;
+  u16 nSkip = pLoop->nSkip;
+  int i, j;
+
+  if( nEq==0 && (pLoop->wsFlags&(WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))==0 ) return;
+  sqlite3StrAccumAppend(pStr, " (", 2);
+  for(i=0; i<nEq; i++){
+    const char *z = explainIndexColumnName(pIndex, i);
+    if( i ) sqlite3StrAccumAppend(pStr, " AND ", 5);
+    sqlite3XPrintf(pStr, i>=nSkip ? "%s=?" : "ANY(%s)", z);
+  }
+
+  j = i;
+  if( pLoop->wsFlags&WHERE_BTM_LIMIT ){
+    explainAppendTerm(pStr, pIndex, pLoop->u.btree.nBtm, j, i, ">");
+    i = 1;
+  }
+  if( pLoop->wsFlags&WHERE_TOP_LIMIT ){
+    explainAppendTerm(pStr, pIndex, pLoop->u.btree.nTop, j, i, "<");
+  }
+  sqlite3StrAccumAppend(pStr, ")", 1);
+}
+
+/*
+** This function is a no-op unless currently processing an EXPLAIN QUERY PLAN
+** command, or if either SQLITE_DEBUG or SQLITE_ENABLE_STMT_SCANSTATUS was
+** defined at compile-time. If it is not a no-op, a single OP_Explain opcode 
+** is added to the output to describe the table scan strategy in pLevel.
+**
+** If an OP_Explain opcode is added to the VM, its address is returned.
+** Otherwise, if no OP_Explain is coded, zero is returned.
+*/
+SQLITE_PRIVATE int sqlite3WhereExplainOneScan(
+  Parse *pParse,                  /* Parse context */
+  SrcList *pTabList,              /* Table list this loop refers to */
+  WhereLevel *pLevel,             /* Scan to write OP_Explain opcode for */
+  int iLevel,                     /* Value for "level" column of output */
+  int iFrom,                      /* Value for "from" column of output */
+  u16 wctrlFlags                  /* Flags passed to sqlite3WhereBegin() */
+){
+  int ret = 0;
+#if !defined(SQLITE_DEBUG) && !defined(SQLITE_ENABLE_STMT_SCANSTATUS)
+  if( pParse->explain==2 )
+#endif
+  {
+    struct SrcList_item *pItem = &pTabList->a[pLevel->iFrom];
+    Vdbe *v = pParse->pVdbe;      /* VM being constructed */
+    sqlite3 *db = pParse->db;     /* Database handle */
+    int iId = pParse->iSelectId;  /* Select id (left-most output column) */
+    int isSearch;                 /* True for a SEARCH. False for SCAN. */
+    WhereLoop *pLoop;             /* The controlling WhereLoop object */
+    u32 flags;                    /* Flags that describe this loop */
+    char *zMsg;                   /* Text to add to EQP output */
+    StrAccum str;                 /* EQP output string */
+    char zBuf[100];               /* Initial space for EQP output string */
+
+    pLoop = pLevel->pWLoop;
+    flags = pLoop->wsFlags;
+    if( (flags&WHERE_MULTI_OR) || (wctrlFlags&WHERE_OR_SUBCLAUSE) ) return 0;
+
+    isSearch = (flags&(WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))!=0
+            || ((flags&WHERE_VIRTUALTABLE)==0 && (pLoop->u.btree.nEq>0))
+            || (wctrlFlags&(WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX));
+
+    sqlite3StrAccumInit(&str, db, zBuf, sizeof(zBuf), SQLITE_MAX_LENGTH);
+    sqlite3StrAccumAppendAll(&str, isSearch ? "SEARCH" : "SCAN");
+    if( pItem->pSelect ){
+      sqlite3XPrintf(&str, " SUBQUERY %d", pItem->iSelectId);
+    }else{
+      sqlite3XPrintf(&str, " TABLE %s", pItem->zName);
+    }
+
+    if( pItem->zAlias ){
+      sqlite3XPrintf(&str, " AS %s", pItem->zAlias);
+    }
+    if( (flags & (WHERE_IPK|WHERE_VIRTUALTABLE))==0 ){
+      const char *zFmt = 0;
+      Index *pIdx;
+
+      assert( pLoop->u.btree.pIndex!=0 );
+      pIdx = pLoop->u.btree.pIndex;
+      assert( !(flags&WHERE_AUTO_INDEX) || (flags&WHERE_IDX_ONLY) );
+      if( !HasRowid(pItem->pTab) && IsPrimaryKeyIndex(pIdx) ){
+        if( isSearch ){
+          zFmt = "PRIMARY KEY";
+        }
+      }else if( flags & WHERE_PARTIALIDX ){
+        zFmt = "AUTOMATIC PARTIAL COVERING INDEX";
+      }else if( flags & WHERE_AUTO_INDEX ){
+        zFmt = "AUTOMATIC COVERING INDEX";
+      }else if( flags & WHERE_IDX_ONLY ){
+        zFmt = "COVERING INDEX %s";
+      }else{
+        zFmt = "INDEX %s";
+      }
+      if( zFmt ){
+        sqlite3StrAccumAppend(&str, " USING ", 7);
+        sqlite3XPrintf(&str, zFmt, pIdx->zName);
+        explainIndexRange(&str, pLoop);
+      }
+    }else if( (flags & WHERE_IPK)!=0 && (flags & WHERE_CONSTRAINT)!=0 ){
+      const char *zRangeOp;
+      if( flags&(WHERE_COLUMN_EQ|WHERE_COLUMN_IN) ){
+        zRangeOp = "=";
+      }else if( (flags&WHERE_BOTH_LIMIT)==WHERE_BOTH_LIMIT ){
+        zRangeOp = ">? AND rowid<";
+      }else if( flags&WHERE_BTM_LIMIT ){
+        zRangeOp = ">";
+      }else{
+        assert( flags&WHERE_TOP_LIMIT);
+        zRangeOp = "<";
+      }
+      sqlite3XPrintf(&str, " USING INTEGER PRIMARY KEY (rowid%s?)",zRangeOp);
+    }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    else if( (flags & WHERE_VIRTUALTABLE)!=0 ){
+      sqlite3XPrintf(&str, " VIRTUAL TABLE INDEX %d:%s",
+                  pLoop->u.vtab.idxNum, pLoop->u.vtab.idxStr);
+    }
+#endif
+#ifdef SQLITE_EXPLAIN_ESTIMATED_ROWS
+    if( pLoop->nOut>=10 ){
+      sqlite3XPrintf(&str, " (~%llu rows)", sqlite3LogEstToInt(pLoop->nOut));
+    }else{
+      sqlite3StrAccumAppend(&str, " (~1 row)", 9);
+    }
+#endif
+    zMsg = sqlite3StrAccumFinish(&str);
+    ret = sqlite3VdbeAddOp4(v, OP_Explain, iId, iLevel, iFrom, zMsg,P4_DYNAMIC);
+  }
+  return ret;
+}
+#endif /* SQLITE_OMIT_EXPLAIN */
+
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+/*
+** Configure the VM passed as the first argument with an
+** sqlite3_stmt_scanstatus() entry corresponding to the scan used to 
+** implement level pLvl. Argument pSrclist is a pointer to the FROM 
+** clause that the scan reads data from.
+**
+** If argument addrExplain is not 0, it must be the address of an 
+** OP_Explain instruction that describes the same loop.
+*/
+SQLITE_PRIVATE void sqlite3WhereAddScanStatus(
+  Vdbe *v,                        /* Vdbe to add scanstatus entry to */
+  SrcList *pSrclist,              /* FROM clause pLvl reads data from */
+  WhereLevel *pLvl,               /* Level to add scanstatus() entry for */
+  int addrExplain                 /* Address of OP_Explain (or 0) */
+){
+  const char *zObj = 0;
+  WhereLoop *pLoop = pLvl->pWLoop;
+  if( (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0  &&  pLoop->u.btree.pIndex!=0 ){
+    zObj = pLoop->u.btree.pIndex->zName;
+  }else{
+    zObj = pSrclist->a[pLvl->iFrom].zName;
+  }
+  sqlite3VdbeScanStatus(
+      v, addrExplain, pLvl->addrBody, pLvl->addrVisit, pLoop->nOut, zObj
+  );
+}
+#endif
+
+
+/*
+** Disable a term in the WHERE clause.  Except, do not disable the term
+** if it controls a LEFT OUTER JOIN and it did not originate in the ON
+** or USING clause of that join.
+**
+** Consider the term t2.z='ok' in the following queries:
+**
+**   (1)  SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x WHERE t2.z='ok'
+**   (2)  SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x AND t2.z='ok'
+**   (3)  SELECT * FROM t1, t2 WHERE t1.a=t2.x AND t2.z='ok'
+**
+** The t2.z='ok' is disabled in the in (2) because it originates
+** in the ON clause.  The term is disabled in (3) because it is not part
+** of a LEFT OUTER JOIN.  In (1), the term is not disabled.
+**
+** Disabling a term causes that term to not be tested in the inner loop
+** of the join.  Disabling is an optimization.  When terms are satisfied
+** by indices, we disable them to prevent redundant tests in the inner
+** loop.  We would get the correct results if nothing were ever disabled,
+** but joins might run a little slower.  The trick is to disable as much
+** as we can without disabling too much.  If we disabled in (1), we'd get
+** the wrong answer.  See ticket #813.
+**
+** If all the children of a term are disabled, then that term is also
+** automatically disabled.  In this way, terms get disabled if derived
+** virtual terms are tested first.  For example:
+**
+**      x GLOB 'abc*' AND x>='abc' AND x<'acd'
+**      \___________/     \______/     \_____/
+**         parent          child1       child2
+**
+** Only the parent term was in the original WHERE clause.  The child1
+** and child2 terms were added by the LIKE optimization.  If both of
+** the virtual child terms are valid, then testing of the parent can be 
+** skipped.
+**
+** Usually the parent term is marked as TERM_CODED.  But if the parent
+** term was originally TERM_LIKE, then the parent gets TERM_LIKECOND instead.
+** The TERM_LIKECOND marking indicates that the term should be coded inside
+** a conditional such that is only evaluated on the second pass of a
+** LIKE-optimization loop, when scanning BLOBs instead of strings.
+*/
+static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){
+  int nLoop = 0;
+  while( ALWAYS(pTerm!=0)
+      && (pTerm->wtFlags & TERM_CODED)==0
+      && (pLevel->iLeftJoin==0 || ExprHasProperty(pTerm->pExpr, EP_FromJoin))
+      && (pLevel->notReady & pTerm->prereqAll)==0
+  ){
+    if( nLoop && (pTerm->wtFlags & TERM_LIKE)!=0 ){
+      pTerm->wtFlags |= TERM_LIKECOND;
+    }else{
+      pTerm->wtFlags |= TERM_CODED;
+    }
+    if( pTerm->iParent<0 ) break;
+    pTerm = &pTerm->pWC->a[pTerm->iParent];
+    pTerm->nChild--;
+    if( pTerm->nChild!=0 ) break;
+    nLoop++;
+  }
+}
+
+/*
+** Code an OP_Affinity opcode to apply the column affinity string zAff
+** to the n registers starting at base. 
+**
+** As an optimization, SQLITE_AFF_BLOB entries (which are no-ops) at the
+** beginning and end of zAff are ignored.  If all entries in zAff are
+** SQLITE_AFF_BLOB, then no code gets generated.
+**
+** This routine makes its own copy of zAff so that the caller is free
+** to modify zAff after this routine returns.
+*/
+static void codeApplyAffinity(Parse *pParse, int base, int n, char *zAff){
+  Vdbe *v = pParse->pVdbe;
+  if( zAff==0 ){
+    assert( pParse->db->mallocFailed );
+    return;
+  }
+  assert( v!=0 );
+
+  /* Adjust base and n to skip over SQLITE_AFF_BLOB entries at the beginning
+  ** and end of the affinity string.
+  */
+  while( n>0 && zAff[0]==SQLITE_AFF_BLOB ){
+    n--;
+    base++;
+    zAff++;
+  }
+  while( n>1 && zAff[n-1]==SQLITE_AFF_BLOB ){
+    n--;
+  }
+
+  /* Code the OP_Affinity opcode if there is anything left to do. */
+  if( n>0 ){
+    sqlite3VdbeAddOp4(v, OP_Affinity, base, n, 0, zAff, n);
+    sqlite3ExprCacheAffinityChange(pParse, base, n);
+  }
+}
+
+/*
+** Expression pRight, which is the RHS of a comparison operation, is 
+** either a vector of n elements or, if n==1, a scalar expression.
+** Before the comparison operation, affinity zAff is to be applied
+** to the pRight values. This function modifies characters within the
+** affinity string to SQLITE_AFF_BLOB if either:
+**
+**   * the comparison will be performed with no affinity, or
+**   * the affinity change in zAff is guaranteed not to change the value.
+*/
+static void updateRangeAffinityStr(
+  Expr *pRight,                   /* RHS of comparison */
+  int n,                          /* Number of vector elements in comparison */
+  char *zAff                      /* Affinity string to modify */
+){
+  int i;
+  for(i=0; i<n; i++){
+    Expr *p = sqlite3VectorFieldSubexpr(pRight, i);
+    if( sqlite3CompareAffinity(p, zAff[i])==SQLITE_AFF_BLOB
+     || sqlite3ExprNeedsNoAffinityChange(p, zAff[i])
+    ){
+      zAff[i] = SQLITE_AFF_BLOB;
+    }
+  }
+}
+
+/*
+** Generate code for a single equality term of the WHERE clause.  An equality
+** term can be either X=expr or X IN (...).   pTerm is the term to be 
+** coded.
+**
+** The current value for the constraint is left in a register, the index
+** of which is returned.  An attempt is made store the result in iTarget but
+** this is only guaranteed for TK_ISNULL and TK_IN constraints.  If the
+** constraint is a TK_EQ or TK_IS, then the current value might be left in
+** some other register and it is the caller's responsibility to compensate.
+**
+** For a constraint of the form X=expr, the expression is evaluated in
+** straight-line code.  For constraints of the form X IN (...)
+** this routine sets up a loop that will iterate over all values of X.
+*/
+static int codeEqualityTerm(
+  Parse *pParse,      /* The parsing context */
+  WhereTerm *pTerm,   /* The term of the WHERE clause to be coded */
+  WhereLevel *pLevel, /* The level of the FROM clause we are working on */
+  int iEq,            /* Index of the equality term within this level */
+  int bRev,           /* True for reverse-order IN operations */
+  int iTarget         /* Attempt to leave results in this register */
+){
+  Expr *pX = pTerm->pExpr;
+  Vdbe *v = pParse->pVdbe;
+  int iReg;                  /* Register holding results */
+
+  assert( pLevel->pWLoop->aLTerm[iEq]==pTerm );
+  assert( iTarget>0 );
+  if( pX->op==TK_EQ || pX->op==TK_IS ){
+    iReg = sqlite3ExprCodeTarget(pParse, pX->pRight, iTarget);
+  }else if( pX->op==TK_ISNULL ){
+    iReg = iTarget;
+    sqlite3VdbeAddOp2(v, OP_Null, 0, iReg);
+#ifndef SQLITE_OMIT_SUBQUERY
+  }else{
+    int eType = IN_INDEX_NOOP;
+    int iTab;
+    struct InLoop *pIn;
+    WhereLoop *pLoop = pLevel->pWLoop;
+    int i;
+    int nEq = 0;
+    int *aiMap = 0;
+
+    if( (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0
+      && pLoop->u.btree.pIndex!=0
+      && pLoop->u.btree.pIndex->aSortOrder[iEq]
+    ){
+      testcase( iEq==0 );
+      testcase( bRev );
+      bRev = !bRev;
+    }
+    assert( pX->op==TK_IN );
+    iReg = iTarget;
+
+    for(i=0; i<iEq; i++){
+      if( pLoop->aLTerm[i] && pLoop->aLTerm[i]->pExpr==pX ){
+        disableTerm(pLevel, pTerm);
+        return iTarget;
+      }
+    }
+    for(i=iEq;i<pLoop->nLTerm; i++){
+      if( ALWAYS(pLoop->aLTerm[i]) && pLoop->aLTerm[i]->pExpr==pX ) nEq++;
+    }
+
+    if( (pX->flags & EP_xIsSelect)==0 || pX->x.pSelect->pEList->nExpr==1 ){
+      eType = sqlite3FindInIndex(pParse, pX, IN_INDEX_LOOP, 0, 0);
+    }else{
+      Select *pSelect = pX->x.pSelect;
+      sqlite3 *db = pParse->db;
+      u16 savedDbOptFlags = db->dbOptFlags;
+      ExprList *pOrigRhs = pSelect->pEList;
+      ExprList *pOrigLhs = pX->pLeft->x.pList;
+      ExprList *pRhs = 0;         /* New Select.pEList for RHS */
+      ExprList *pLhs = 0;         /* New pX->pLeft vector */
+
+      for(i=iEq;i<pLoop->nLTerm; i++){
+        if( pLoop->aLTerm[i]->pExpr==pX ){
+          int iField = pLoop->aLTerm[i]->iField - 1;
+          Expr *pNewRhs = sqlite3ExprDup(db, pOrigRhs->a[iField].pExpr, 0);
+          Expr *pNewLhs = sqlite3ExprDup(db, pOrigLhs->a[iField].pExpr, 0);
+
+          pRhs = sqlite3ExprListAppend(pParse, pRhs, pNewRhs);
+          pLhs = sqlite3ExprListAppend(pParse, pLhs, pNewLhs);
+        }
+      }
+      if( !db->mallocFailed ){
+        Expr *pLeft = pX->pLeft;
+
+        if( pSelect->pOrderBy ){
+          /* If the SELECT statement has an ORDER BY clause, zero the 
+          ** iOrderByCol variables. These are set to non-zero when an 
+          ** ORDER BY term exactly matches one of the terms of the 
+          ** result-set. Since the result-set of the SELECT statement may
+          ** have been modified or reordered, these variables are no longer 
+          ** set correctly.  Since setting them is just an optimization, 
+          ** it's easiest just to zero them here.  */
+          ExprList *pOrderBy = pSelect->pOrderBy;
+          for(i=0; i<pOrderBy->nExpr; i++){
+            pOrderBy->a[i].u.x.iOrderByCol = 0;
+          }
+        }
+
+        /* Take care here not to generate a TK_VECTOR containing only a
+        ** single value. Since the parser never creates such a vector, some
+        ** of the subroutines do not handle this case.  */
+        if( pLhs->nExpr==1 ){
+          pX->pLeft = pLhs->a[0].pExpr;
+        }else{
+          pLeft->x.pList = pLhs;
+          aiMap = (int*)sqlite3DbMallocZero(pParse->db, sizeof(int) * nEq);
+          testcase( aiMap==0 );
+        }
+        pSelect->pEList = pRhs;
+        db->dbOptFlags |= SQLITE_QueryFlattener;
+        eType = sqlite3FindInIndex(pParse, pX, IN_INDEX_LOOP, 0, aiMap);
+        db->dbOptFlags = savedDbOptFlags;
+        testcase( aiMap!=0 && aiMap[0]!=0 );
+        pSelect->pEList = pOrigRhs;
+        pLeft->x.pList = pOrigLhs;
+        pX->pLeft = pLeft;
+      }
+      sqlite3ExprListDelete(pParse->db, pLhs);
+      sqlite3ExprListDelete(pParse->db, pRhs);
+    }
+
+    if( eType==IN_INDEX_INDEX_DESC ){
+      testcase( bRev );
+      bRev = !bRev;
+    }
+    iTab = pX->iTable;
+    sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iTab, 0);
+    VdbeCoverageIf(v, bRev);
+    VdbeCoverageIf(v, !bRev);
+    assert( (pLoop->wsFlags & WHERE_MULTI_OR)==0 );
+
+    pLoop->wsFlags |= WHERE_IN_ABLE;
+    if( pLevel->u.in.nIn==0 ){
+      pLevel->addrNxt = sqlite3VdbeMakeLabel(v);
+    }
+
+    i = pLevel->u.in.nIn;
+    pLevel->u.in.nIn += nEq;
+    pLevel->u.in.aInLoop =
+       sqlite3DbReallocOrFree(pParse->db, pLevel->u.in.aInLoop,
+                              sizeof(pLevel->u.in.aInLoop[0])*pLevel->u.in.nIn);
+    pIn = pLevel->u.in.aInLoop;
+    if( pIn ){
+      int iMap = 0;               /* Index in aiMap[] */
+      pIn += i;
+      for(i=iEq;i<pLoop->nLTerm; i++){
+        if( pLoop->aLTerm[i]->pExpr==pX ){
+          int iOut = iReg + i - iEq;
+          if( eType==IN_INDEX_ROWID ){
+            testcase( nEq>1 );  /* Happens with a UNIQUE index on ROWID */
+            pIn->addrInTop = sqlite3VdbeAddOp2(v, OP_Rowid, iTab, iOut);
+          }else{
+            int iCol = aiMap ? aiMap[iMap++] : 0;
+            pIn->addrInTop = sqlite3VdbeAddOp3(v,OP_Column,iTab, iCol, iOut);
+          }
+          sqlite3VdbeAddOp1(v, OP_IsNull, iOut); VdbeCoverage(v);
+          if( i==iEq ){
+            pIn->iCur = iTab;
+            pIn->eEndLoopOp = bRev ? OP_PrevIfOpen : OP_NextIfOpen;
+          }else{
+            pIn->eEndLoopOp = OP_Noop;
+          }
+          pIn++;
+        }
+      }
+    }else{
+      pLevel->u.in.nIn = 0;
+    }
+    sqlite3DbFree(pParse->db, aiMap);
+#endif
+  }
+  disableTerm(pLevel, pTerm);
+  return iReg;
+}
+
+/*
+** Generate code that will evaluate all == and IN constraints for an
+** index scan.
+**
+** For example, consider table t1(a,b,c,d,e,f) with index i1(a,b,c).
+** Suppose the WHERE clause is this:  a==5 AND b IN (1,2,3) AND c>5 AND c<10
+** The index has as many as three equality constraints, but in this
+** example, the third "c" value is an inequality.  So only two 
+** constraints are coded.  This routine will generate code to evaluate
+** a==5 and b IN (1,2,3).  The current values for a and b will be stored
+** in consecutive registers and the index of the first register is returned.
+**
+** In the example above nEq==2.  But this subroutine works for any value
+** of nEq including 0.  If nEq==0, this routine is nearly a no-op.
+** The only thing it does is allocate the pLevel->iMem memory cell and
+** compute the affinity string.
+**
+** The nExtraReg parameter is 0 or 1.  It is 0 if all WHERE clause constraints
+** are == or IN and are covered by the nEq.  nExtraReg is 1 if there is
+** an inequality constraint (such as the "c>=5 AND c<10" in the example) that
+** occurs after the nEq quality constraints.
+**
+** This routine allocates a range of nEq+nExtraReg memory cells and returns
+** the index of the first memory cell in that range. The code that
+** calls this routine will use that memory range to store keys for
+** start and termination conditions of the loop.
+** key value of the loop.  If one or more IN operators appear, then
+** this routine allocates an additional nEq memory cells for internal
+** use.
+**
+** Before returning, *pzAff is set to point to a buffer containing a
+** copy of the column affinity string of the index allocated using
+** sqlite3DbMalloc(). Except, entries in the copy of the string associated
+** with equality constraints that use BLOB or NONE affinity are set to
+** SQLITE_AFF_BLOB. This is to deal with SQL such as the following:
+**
+**   CREATE TABLE t1(a TEXT PRIMARY KEY, b);
+**   SELECT ... FROM t1 AS t2, t1 WHERE t1.a = t2.b;
+**
+** In the example above, the index on t1(a) has TEXT affinity. But since
+** the right hand side of the equality constraint (t2.b) has BLOB/NONE affinity,
+** no conversion should be attempted before using a t2.b value as part of
+** a key to search the index. Hence the first byte in the returned affinity
+** string in this example would be set to SQLITE_AFF_BLOB.
+*/
+static int codeAllEqualityTerms(
+  Parse *pParse,        /* Parsing context */
+  WhereLevel *pLevel,   /* Which nested loop of the FROM we are coding */
+  int bRev,             /* Reverse the order of IN operators */
+  int nExtraReg,        /* Number of extra registers to allocate */
+  char **pzAff          /* OUT: Set to point to affinity string */
+){
+  u16 nEq;                      /* The number of == or IN constraints to code */
+  u16 nSkip;                    /* Number of left-most columns to skip */
+  Vdbe *v = pParse->pVdbe;      /* The vm under construction */
+  Index *pIdx;                  /* The index being used for this loop */
+  WhereTerm *pTerm;             /* A single constraint term */
+  WhereLoop *pLoop;             /* The WhereLoop object */
+  int j;                        /* Loop counter */
+  int regBase;                  /* Base register */
+  int nReg;                     /* Number of registers to allocate */
+  char *zAff;                   /* Affinity string to return */
+
+  /* This module is only called on query plans that use an index. */
+  pLoop = pLevel->pWLoop;
+  assert( (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0 );
+  nEq = pLoop->u.btree.nEq;
+  nSkip = pLoop->nSkip;
+  pIdx = pLoop->u.btree.pIndex;
+  assert( pIdx!=0 );
+
+  /* Figure out how many memory cells we will need then allocate them.
+  */
+  regBase = pParse->nMem + 1;
+  nReg = pLoop->u.btree.nEq + nExtraReg;
+  pParse->nMem += nReg;
+
+  zAff = sqlite3DbStrDup(pParse->db,sqlite3IndexAffinityStr(pParse->db,pIdx));
+  assert( zAff!=0 || pParse->db->mallocFailed );
+
+  if( nSkip ){
+    int iIdxCur = pLevel->iIdxCur;
+    sqlite3VdbeAddOp1(v, (bRev?OP_Last:OP_Rewind), iIdxCur);
+    VdbeCoverageIf(v, bRev==0);
+    VdbeCoverageIf(v, bRev!=0);
+    VdbeComment((v, "begin skip-scan on %s", pIdx->zName));
+    j = sqlite3VdbeAddOp0(v, OP_Goto);
+    pLevel->addrSkip = sqlite3VdbeAddOp4Int(v, (bRev?OP_SeekLT:OP_SeekGT),
+                            iIdxCur, 0, regBase, nSkip);
+    VdbeCoverageIf(v, bRev==0);
+    VdbeCoverageIf(v, bRev!=0);
+    sqlite3VdbeJumpHere(v, j);
+    for(j=0; j<nSkip; j++){
+      sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, j, regBase+j);
+      testcase( pIdx->aiColumn[j]==XN_EXPR );
+      VdbeComment((v, "%s", explainIndexColumnName(pIdx, j)));
+    }
+  }    
+
+  /* Evaluate the equality constraints
+  */
+  assert( zAff==0 || (int)strlen(zAff)>=nEq );
+  for(j=nSkip; j<nEq; j++){
+    int r1;
+    pTerm = pLoop->aLTerm[j];
+    assert( pTerm!=0 );
+    /* The following testcase is true for indices with redundant columns. 
+    ** Ex: CREATE INDEX i1 ON t1(a,b,a); SELECT * FROM t1 WHERE a=0 AND b=0; */
+    testcase( (pTerm->wtFlags & TERM_CODED)!=0 );
+    testcase( pTerm->wtFlags & TERM_VIRTUAL );
+    r1 = codeEqualityTerm(pParse, pTerm, pLevel, j, bRev, regBase+j);
+    if( r1!=regBase+j ){
+      if( nReg==1 ){
+        sqlite3ReleaseTempReg(pParse, regBase);
+        regBase = r1;
+      }else{
+        sqlite3VdbeAddOp2(v, OP_SCopy, r1, regBase+j);
+      }
+    }
+    if( pTerm->eOperator & WO_IN ){
+      if( pTerm->pExpr->flags & EP_xIsSelect ){
+        /* No affinity ever needs to be (or should be) applied to a value
+        ** from the RHS of an "? IN (SELECT ...)" expression. The 
+        ** sqlite3FindInIndex() routine has already ensured that the 
+        ** affinity of the comparison has been applied to the value.  */
+        if( zAff ) zAff[j] = SQLITE_AFF_BLOB;
+      }
+    }else if( (pTerm->eOperator & WO_ISNULL)==0 ){
+      Expr *pRight = pTerm->pExpr->pRight;
+      if( (pTerm->wtFlags & TERM_IS)==0 && sqlite3ExprCanBeNull(pRight) ){
+        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+j, pLevel->addrBrk);
+        VdbeCoverage(v);
+      }
+      if( zAff ){
+        if( sqlite3CompareAffinity(pRight, zAff[j])==SQLITE_AFF_BLOB ){
+          zAff[j] = SQLITE_AFF_BLOB;
+        }
+        if( sqlite3ExprNeedsNoAffinityChange(pRight, zAff[j]) ){
+          zAff[j] = SQLITE_AFF_BLOB;
+        }
+      }
+    }
+  }
+  *pzAff = zAff;
+  return regBase;
+}
+
+#ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
+/*
+** If the most recently coded instruction is a constant range constraint
+** (a string literal) that originated from the LIKE optimization, then 
+** set P3 and P5 on the OP_String opcode so that the string will be cast
+** to a BLOB at appropriate times.
+**
+** The LIKE optimization trys to evaluate "x LIKE 'abc%'" as a range
+** expression: "x>='ABC' AND x<'abd'".  But this requires that the range
+** scan loop run twice, once for strings and a second time for BLOBs.
+** The OP_String opcodes on the second pass convert the upper and lower
+** bound string constants to blobs.  This routine makes the necessary changes
+** to the OP_String opcodes for that to happen.
+**
+** Except, of course, if SQLITE_LIKE_DOESNT_MATCH_BLOBS is defined, then
+** only the one pass through the string space is required, so this routine
+** becomes a no-op.
+*/
+static void whereLikeOptimizationStringFixup(
+  Vdbe *v,                /* prepared statement under construction */
+  WhereLevel *pLevel,     /* The loop that contains the LIKE operator */
+  WhereTerm *pTerm        /* The upper or lower bound just coded */
+){
+  if( pTerm->wtFlags & TERM_LIKEOPT ){
+    VdbeOp *pOp;
+    assert( pLevel->iLikeRepCntr>0 );
+    pOp = sqlite3VdbeGetOp(v, -1);
+    assert( pOp!=0 );
+    assert( pOp->opcode==OP_String8 
+            || pTerm->pWC->pWInfo->pParse->db->mallocFailed );
+    pOp->p3 = (int)(pLevel->iLikeRepCntr>>1);  /* Register holding counter */
+    pOp->p5 = (u8)(pLevel->iLikeRepCntr&1);    /* ASC or DESC */
+  }
+}
+#else
+# define whereLikeOptimizationStringFixup(A,B,C)
+#endif
+
+#ifdef SQLITE_ENABLE_CURSOR_HINTS
+/*
+** Information is passed from codeCursorHint() down to individual nodes of
+** the expression tree (by sqlite3WalkExpr()) using an instance of this
+** structure.
+*/
+struct CCurHint {
+  int iTabCur;    /* Cursor for the main table */
+  int iIdxCur;    /* Cursor for the index, if pIdx!=0.  Unused otherwise */
+  Index *pIdx;    /* The index used to access the table */
+};
+
+/*
+** This function is called for every node of an expression that is a candidate
+** for a cursor hint on an index cursor.  For TK_COLUMN nodes that reference
+** the table CCurHint.iTabCur, verify that the same column can be
+** accessed through the index.  If it cannot, then set pWalker->eCode to 1.
+*/
+static int codeCursorHintCheckExpr(Walker *pWalker, Expr *pExpr){
+  struct CCurHint *pHint = pWalker->u.pCCurHint;
+  assert( pHint->pIdx!=0 );
+  if( pExpr->op==TK_COLUMN
+   && pExpr->iTable==pHint->iTabCur
+   && sqlite3ColumnOfIndex(pHint->pIdx, pExpr->iColumn)<0
+  ){
+    pWalker->eCode = 1;
+  }
+  return WRC_Continue;
+}
+
+/*
+** Test whether or not expression pExpr, which was part of a WHERE clause,
+** should be included in the cursor-hint for a table that is on the rhs
+** of a LEFT JOIN. Set Walker.eCode to non-zero before returning if the 
+** expression is not suitable.
+**
+** An expression is unsuitable if it might evaluate to non NULL even if
+** a TK_COLUMN node that does affect the value of the expression is set
+** to NULL. For example:
+**
+**   col IS NULL
+**   col IS NOT NULL
+**   coalesce(col, 1)
+**   CASE WHEN col THEN 0 ELSE 1 END
+*/
+static int codeCursorHintIsOrFunction(Walker *pWalker, Expr *pExpr){
+  if( pExpr->op==TK_IS 
+   || pExpr->op==TK_ISNULL || pExpr->op==TK_ISNOT 
+   || pExpr->op==TK_NOTNULL || pExpr->op==TK_CASE 
+  ){
+    pWalker->eCode = 1;
+  }else if( pExpr->op==TK_FUNCTION ){
+    int d1;
+    char d2[3];
+    if( 0==sqlite3IsLikeFunction(pWalker->pParse->db, pExpr, &d1, d2) ){
+      pWalker->eCode = 1;
+    }
+  }
+
+  return WRC_Continue;
+}
+
+
+/*
+** This function is called on every node of an expression tree used as an
+** argument to the OP_CursorHint instruction. If the node is a TK_COLUMN
+** that accesses any table other than the one identified by
+** CCurHint.iTabCur, then do the following:
+**
+**   1) allocate a register and code an OP_Column instruction to read 
+**      the specified column into the new register, and
+**
+**   2) transform the expression node to a TK_REGISTER node that reads 
+**      from the newly populated register.
+**
+** Also, if the node is a TK_COLUMN that does access the table idenified
+** by pCCurHint.iTabCur, and an index is being used (which we will
+** know because CCurHint.pIdx!=0) then transform the TK_COLUMN into
+** an access of the index rather than the original table.
+*/
+static int codeCursorHintFixExpr(Walker *pWalker, Expr *pExpr){
+  int rc = WRC_Continue;
+  struct CCurHint *pHint = pWalker->u.pCCurHint;
+  if( pExpr->op==TK_COLUMN ){
+    if( pExpr->iTable!=pHint->iTabCur ){
+      Vdbe *v = pWalker->pParse->pVdbe;
+      int reg = ++pWalker->pParse->nMem;   /* Register for column value */
+      sqlite3ExprCodeGetColumnOfTable(
+          v, pExpr->pTab, pExpr->iTable, pExpr->iColumn, reg
+      );
+      pExpr->op = TK_REGISTER;
+      pExpr->iTable = reg;
+    }else if( pHint->pIdx!=0 ){
+      pExpr->iTable = pHint->iIdxCur;
+      pExpr->iColumn = sqlite3ColumnOfIndex(pHint->pIdx, pExpr->iColumn);
+      assert( pExpr->iColumn>=0 );
+    }
+  }else if( pExpr->op==TK_AGG_FUNCTION ){
+    /* An aggregate function in the WHERE clause of a query means this must
+    ** be a correlated sub-query, and expression pExpr is an aggregate from
+    ** the parent context. Do not walk the function arguments in this case.
+    **
+    ** todo: It should be possible to replace this node with a TK_REGISTER
+    ** expression, as the result of the expression must be stored in a 
+    ** register at this point. The same holds for TK_AGG_COLUMN nodes. */
+    rc = WRC_Prune;
+  }
+  return rc;
+}
+
+/*
+** Insert an OP_CursorHint instruction if it is appropriate to do so.
+*/
+static void codeCursorHint(
+  struct SrcList_item *pTabItem,  /* FROM clause item */
+  WhereInfo *pWInfo,    /* The where clause */
+  WhereLevel *pLevel,   /* Which loop to provide hints for */
+  WhereTerm *pEndRange  /* Hint this end-of-scan boundary term if not NULL */
+){
+  Parse *pParse = pWInfo->pParse;
+  sqlite3 *db = pParse->db;
+  Vdbe *v = pParse->pVdbe;
+  Expr *pExpr = 0;
+  WhereLoop *pLoop = pLevel->pWLoop;
+  int iCur;
+  WhereClause *pWC;
+  WhereTerm *pTerm;
+  int i, j;
+  struct CCurHint sHint;
+  Walker sWalker;
+
+  if( OptimizationDisabled(db, SQLITE_CursorHints) ) return;
+  iCur = pLevel->iTabCur;
+  assert( iCur==pWInfo->pTabList->a[pLevel->iFrom].iCursor );
+  sHint.iTabCur = iCur;
+  sHint.iIdxCur = pLevel->iIdxCur;
+  sHint.pIdx = pLoop->u.btree.pIndex;
+  memset(&sWalker, 0, sizeof(sWalker));
+  sWalker.pParse = pParse;
+  sWalker.u.pCCurHint = &sHint;
+  pWC = &pWInfo->sWC;
+  for(i=0; i<pWC->nTerm; i++){
+    pTerm = &pWC->a[i];
+    if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
+    if( pTerm->prereqAll & pLevel->notReady ) continue;
+
+    /* Any terms specified as part of the ON(...) clause for any LEFT 
+    ** JOIN for which the current table is not the rhs are omitted
+    ** from the cursor-hint. 
+    **
+    ** If this table is the rhs of a LEFT JOIN, "IS" or "IS NULL" terms 
+    ** that were specified as part of the WHERE clause must be excluded.
+    ** This is to address the following:
+    **
+    **   SELECT ... t1 LEFT JOIN t2 ON (t1.a=t2.b) WHERE t2.c IS NULL;
+    **
+    ** Say there is a single row in t2 that matches (t1.a=t2.b), but its
+    ** t2.c values is not NULL. If the (t2.c IS NULL) constraint is 
+    ** pushed down to the cursor, this row is filtered out, causing
+    ** SQLite to synthesize a row of NULL values. Which does match the
+    ** WHERE clause, and so the query returns a row. Which is incorrect.
+    **
+    ** For the same reason, WHERE terms such as:
+    **
+    **   WHERE 1 = (t2.c IS NULL)
+    **
+    ** are also excluded. See codeCursorHintIsOrFunction() for details.
+    */
+    if( pTabItem->fg.jointype & JT_LEFT ){
+      Expr *pExpr = pTerm->pExpr;
+      if( !ExprHasProperty(pExpr, EP_FromJoin) 
+       || pExpr->iRightJoinTable!=pTabItem->iCursor
+      ){
+        sWalker.eCode = 0;
+        sWalker.xExprCallback = codeCursorHintIsOrFunction;
+        sqlite3WalkExpr(&sWalker, pTerm->pExpr);
+        if( sWalker.eCode ) continue;
+      }
+    }else{
+      if( ExprHasProperty(pTerm->pExpr, EP_FromJoin) ) continue;
+    }
+
+    /* All terms in pWLoop->aLTerm[] except pEndRange are used to initialize
+    ** the cursor.  These terms are not needed as hints for a pure range
+    ** scan (that has no == terms) so omit them. */
+    if( pLoop->u.btree.nEq==0 && pTerm!=pEndRange ){
+      for(j=0; j<pLoop->nLTerm && pLoop->aLTerm[j]!=pTerm; j++){}
+      if( j<pLoop->nLTerm ) continue;
+    }
+
+    /* No subqueries or non-deterministic functions allowed */
+    if( sqlite3ExprContainsSubquery(pTerm->pExpr) ) continue;
+
+    /* For an index scan, make sure referenced columns are actually in
+    ** the index. */
+    if( sHint.pIdx!=0 ){
+      sWalker.eCode = 0;
+      sWalker.xExprCallback = codeCursorHintCheckExpr;
+      sqlite3WalkExpr(&sWalker, pTerm->pExpr);
+      if( sWalker.eCode ) continue;
+    }
+
+    /* If we survive all prior tests, that means this term is worth hinting */
+    pExpr = sqlite3ExprAnd(db, pExpr, sqlite3ExprDup(db, pTerm->pExpr, 0));
+  }
+  if( pExpr!=0 ){
+    sWalker.xExprCallback = codeCursorHintFixExpr;
+    sqlite3WalkExpr(&sWalker, pExpr);
+    sqlite3VdbeAddOp4(v, OP_CursorHint, 
+                      (sHint.pIdx ? sHint.iIdxCur : sHint.iTabCur), 0, 0,
+                      (const char*)pExpr, P4_EXPR);
+  }
+}
+#else
+# define codeCursorHint(A,B,C,D)  /* No-op */
+#endif /* SQLITE_ENABLE_CURSOR_HINTS */
+
+/*
+** Cursor iCur is open on an intkey b-tree (a table). Register iRowid contains
+** a rowid value just read from cursor iIdxCur, open on index pIdx. This
+** function generates code to do a deferred seek of cursor iCur to the 
+** rowid stored in register iRowid.
+**
+** Normally, this is just:
+**
+**   OP_Seek $iCur $iRowid
+**
+** However, if the scan currently being coded is a branch of an OR-loop and
+** the statement currently being coded is a SELECT, then P3 of the OP_Seek
+** is set to iIdxCur and P4 is set to point to an array of integers
+** containing one entry for each column of the table cursor iCur is open 
+** on. For each table column, if the column is the i'th column of the 
+** index, then the corresponding array entry is set to (i+1). If the column
+** does not appear in the index at all, the array entry is set to 0.
+*/
+static void codeDeferredSeek(
+  WhereInfo *pWInfo,              /* Where clause context */
+  Index *pIdx,                    /* Index scan is using */
+  int iCur,                       /* Cursor for IPK b-tree */
+  int iIdxCur                     /* Index cursor */
+){
+  Parse *pParse = pWInfo->pParse; /* Parse context */
+  Vdbe *v = pParse->pVdbe;        /* Vdbe to generate code within */
+
+  assert( iIdxCur>0 );
+  assert( pIdx->aiColumn[pIdx->nColumn-1]==-1 );
+  
+  sqlite3VdbeAddOp3(v, OP_Seek, iIdxCur, 0, iCur);
+  if( (pWInfo->wctrlFlags & WHERE_OR_SUBCLAUSE)
+   && DbMaskAllZero(sqlite3ParseToplevel(pParse)->writeMask)
+  ){
+    int i;
+    Table *pTab = pIdx->pTable;
+    int *ai = (int*)sqlite3DbMallocZero(pParse->db, sizeof(int)*(pTab->nCol+1));
+    if( ai ){
+      ai[0] = pTab->nCol;
+      for(i=0; i<pIdx->nColumn-1; i++){
+        assert( pIdx->aiColumn[i]<pTab->nCol );
+        if( pIdx->aiColumn[i]>=0 ) ai[pIdx->aiColumn[i]+1] = i+1;
+      }
+      sqlite3VdbeChangeP4(v, -1, (char*)ai, P4_INTARRAY);
+    }
+  }
+}
+
+/*
+** If the expression passed as the second argument is a vector, generate
+** code to write the first nReg elements of the vector into an array
+** of registers starting with iReg.
+**
+** If the expression is not a vector, then nReg must be passed 1. In
+** this case, generate code to evaluate the expression and leave the
+** result in register iReg.
+*/
+static void codeExprOrVector(Parse *pParse, Expr *p, int iReg, int nReg){
+  assert( nReg>0 );
+  if( sqlite3ExprIsVector(p) ){
+#ifndef SQLITE_OMIT_SUBQUERY
+    if( (p->flags & EP_xIsSelect) ){
+      Vdbe *v = pParse->pVdbe;
+      int iSelect = sqlite3CodeSubselect(pParse, p, 0, 0);
+      sqlite3VdbeAddOp3(v, OP_Copy, iSelect, iReg, nReg-1);
+    }else
+#endif
+    {
+      int i;
+      ExprList *pList = p->x.pList;
+      assert( nReg<=pList->nExpr );
+      for(i=0; i<nReg; i++){
+        sqlite3ExprCode(pParse, pList->a[i].pExpr, iReg+i);
+      }
+    }
+  }else{
+    assert( nReg==1 );
+    sqlite3ExprCode(pParse, p, iReg);
+  }
+}
+
+/*
+** Generate code for the start of the iLevel-th loop in the WHERE clause
+** implementation described by pWInfo.
+*/
+SQLITE_PRIVATE Bitmask sqlite3WhereCodeOneLoopStart(
+  WhereInfo *pWInfo,   /* Complete information about the WHERE clause */
+  int iLevel,          /* Which level of pWInfo->a[] should be coded */
+  Bitmask notReady     /* Which tables are currently available */
+){
+  int j, k;            /* Loop counters */
+  int iCur;            /* The VDBE cursor for the table */
+  int addrNxt;         /* Where to jump to continue with the next IN case */
+  int omitTable;       /* True if we use the index only */
+  int bRev;            /* True if we need to scan in reverse order */
+  WhereLevel *pLevel;  /* The where level to be coded */
+  WhereLoop *pLoop;    /* The WhereLoop object being coded */
+  WhereClause *pWC;    /* Decomposition of the entire WHERE clause */
+  WhereTerm *pTerm;               /* A WHERE clause term */
+  Parse *pParse;                  /* Parsing context */
+  sqlite3 *db;                    /* Database connection */
+  Vdbe *v;                        /* The prepared stmt under constructions */
+  struct SrcList_item *pTabItem;  /* FROM clause term being coded */
+  int addrBrk;                    /* Jump here to break out of the loop */
+  int addrCont;                   /* Jump here to continue with next cycle */
+  int iRowidReg = 0;        /* Rowid is stored in this register, if not zero */
+  int iReleaseReg = 0;      /* Temp register to free before returning */
+
+  pParse = pWInfo->pParse;
+  v = pParse->pVdbe;
+  pWC = &pWInfo->sWC;
+  db = pParse->db;
+  pLevel = &pWInfo->a[iLevel];
+  pLoop = pLevel->pWLoop;
+  pTabItem = &pWInfo->pTabList->a[pLevel->iFrom];
+  iCur = pTabItem->iCursor;
+  pLevel->notReady = notReady & ~sqlite3WhereGetMask(&pWInfo->sMaskSet, iCur);
+  bRev = (pWInfo->revMask>>iLevel)&1;
+  omitTable = (pLoop->wsFlags & WHERE_IDX_ONLY)!=0 
+           && (pWInfo->wctrlFlags & WHERE_OR_SUBCLAUSE)==0;
+  VdbeModuleComment((v, "Begin WHERE-loop%d: %s",iLevel,pTabItem->pTab->zName));
+
+  /* Create labels for the "break" and "continue" instructions
+  ** for the current loop.  Jump to addrBrk to break out of a loop.
+  ** Jump to cont to go immediately to the next iteration of the
+  ** loop.
+  **
+  ** When there is an IN operator, we also have a "addrNxt" label that
+  ** means to continue with the next IN value combination.  When
+  ** there are no IN operators in the constraints, the "addrNxt" label
+  ** is the same as "addrBrk".
+  */
+  addrBrk = pLevel->addrBrk = pLevel->addrNxt = sqlite3VdbeMakeLabel(v);
+  addrCont = pLevel->addrCont = sqlite3VdbeMakeLabel(v);
+
+  /* If this is the right table of a LEFT OUTER JOIN, allocate and
+  ** initialize a memory cell that records if this table matches any
+  ** row of the left table of the join.
+  */
+  if( pLevel->iFrom>0 && (pTabItem[0].fg.jointype & JT_LEFT)!=0 ){
+    pLevel->iLeftJoin = ++pParse->nMem;
+    sqlite3VdbeAddOp2(v, OP_Integer, 0, pLevel->iLeftJoin);
+    VdbeComment((v, "init LEFT JOIN no-match flag"));
+  }
+
+  /* Special case of a FROM clause subquery implemented as a co-routine */
+  if( pTabItem->fg.viaCoroutine ){
+    int regYield = pTabItem->regReturn;
+    sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, pTabItem->addrFillSub);
+    pLevel->p2 =  sqlite3VdbeAddOp2(v, OP_Yield, regYield, addrBrk);
+    VdbeCoverage(v);
+    VdbeComment((v, "next row of \"%s\"", pTabItem->pTab->zName));
+    pLevel->op = OP_Goto;
+  }else
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  if(  (pLoop->wsFlags & WHERE_VIRTUALTABLE)!=0 ){
+    /* Case 1:  The table is a virtual-table.  Use the VFilter and VNext
+    **          to access the data.
+    */
+    int iReg;   /* P3 Value for OP_VFilter */
+    int addrNotFound;
+    int nConstraint = pLoop->nLTerm;
+    int iIn;    /* Counter for IN constraints */
+
+    sqlite3ExprCachePush(pParse);
+    iReg = sqlite3GetTempRange(pParse, nConstraint+2);
+    addrNotFound = pLevel->addrBrk;
+    for(j=0; j<nConstraint; j++){
+      int iTarget = iReg+j+2;
+      pTerm = pLoop->aLTerm[j];
+      if( NEVER(pTerm==0) ) continue;
+      if( pTerm->eOperator & WO_IN ){
+        codeEqualityTerm(pParse, pTerm, pLevel, j, bRev, iTarget);
+        addrNotFound = pLevel->addrNxt;
+      }else{
+        Expr *pRight = pTerm->pExpr->pRight;
+        codeExprOrVector(pParse, pRight, iTarget, 1);
+      }
+    }
+    sqlite3VdbeAddOp2(v, OP_Integer, pLoop->u.vtab.idxNum, iReg);
+    sqlite3VdbeAddOp2(v, OP_Integer, nConstraint, iReg+1);
+    sqlite3VdbeAddOp4(v, OP_VFilter, iCur, addrNotFound, iReg,
+                      pLoop->u.vtab.idxStr,
+                      pLoop->u.vtab.needFree ? P4_MPRINTF : P4_STATIC);
+    VdbeCoverage(v);
+    pLoop->u.vtab.needFree = 0;
+    pLevel->p1 = iCur;
+    pLevel->op = pWInfo->eOnePass ? OP_Noop : OP_VNext;
+    pLevel->p2 = sqlite3VdbeCurrentAddr(v);
+    iIn = pLevel->u.in.nIn;
+    for(j=nConstraint-1; j>=0; j--){
+      pTerm = pLoop->aLTerm[j];
+      if( j<16 && (pLoop->u.vtab.omitMask>>j)&1 ){
+        disableTerm(pLevel, pTerm);
+      }else if( (pTerm->eOperator & WO_IN)!=0 ){
+        Expr *pCompare;  /* The comparison operator */
+        Expr *pRight;    /* RHS of the comparison */
+        VdbeOp *pOp;     /* Opcode to access the value of the IN constraint */
+
+        /* Reload the constraint value into reg[iReg+j+2].  The same value
+        ** was loaded into the same register prior to the OP_VFilter, but
+        ** the xFilter implementation might have changed the datatype or
+        ** encoding of the value in the register, so it *must* be reloaded. */
+        assert( pLevel->u.in.aInLoop!=0 || db->mallocFailed );
+        if( !db->mallocFailed ){
+          assert( iIn>0 );
+          pOp = sqlite3VdbeGetOp(v, pLevel->u.in.aInLoop[--iIn].addrInTop);
+          assert( pOp->opcode==OP_Column || pOp->opcode==OP_Rowid );
+          assert( pOp->opcode!=OP_Column || pOp->p3==iReg+j+2 );
+          assert( pOp->opcode!=OP_Rowid || pOp->p2==iReg+j+2 );
+          testcase( pOp->opcode==OP_Rowid );
+          sqlite3VdbeAddOp3(v, pOp->opcode, pOp->p1, pOp->p2, pOp->p3);
+        }
+
+        /* Generate code that will continue to the next row if 
+        ** the IN constraint is not satisfied */
+        pCompare = sqlite3PExpr(pParse, TK_EQ, 0, 0, 0);
+        assert( pCompare!=0 || db->mallocFailed );
+        if( pCompare ){
+          pCompare->pLeft = pTerm->pExpr->pLeft;
+          pCompare->pRight = pRight = sqlite3Expr(db, TK_REGISTER, 0);
+          if( pRight ){
+            pRight->iTable = iReg+j+2;
+            sqlite3ExprIfFalse(pParse, pCompare, pLevel->addrCont, 0);
+          }
+          pCompare->pLeft = 0;
+          sqlite3ExprDelete(db, pCompare);
+        }
+      }
+    }
+    /* These registers need to be preserved in case there is an IN operator
+    ** loop.  So we could deallocate the registers here (and potentially
+    ** reuse them later) if (pLoop->wsFlags & WHERE_IN_ABLE)==0.  But it seems
+    ** simpler and safer to simply not reuse the registers.
+    **
+    **    sqlite3ReleaseTempRange(pParse, iReg, nConstraint+2);
+    */
+    sqlite3ExprCachePop(pParse);
+  }else
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+  if( (pLoop->wsFlags & WHERE_IPK)!=0
+   && (pLoop->wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_EQ))!=0
+  ){
+    /* Case 2:  We can directly reference a single row using an
+    **          equality comparison against the ROWID field.  Or
+    **          we reference multiple rows using a "rowid IN (...)"
+    **          construct.
+    */
+    assert( pLoop->u.btree.nEq==1 );
+    pTerm = pLoop->aLTerm[0];
+    assert( pTerm!=0 );
+    assert( pTerm->pExpr!=0 );
+    assert( omitTable==0 );
+    testcase( pTerm->wtFlags & TERM_VIRTUAL );
+    iReleaseReg = ++pParse->nMem;
+    iRowidReg = codeEqualityTerm(pParse, pTerm, pLevel, 0, bRev, iReleaseReg);
+    if( iRowidReg!=iReleaseReg ) sqlite3ReleaseTempReg(pParse, iReleaseReg);
+    addrNxt = pLevel->addrNxt;
+    sqlite3VdbeAddOp3(v, OP_SeekRowid, iCur, addrNxt, iRowidReg);
+    VdbeCoverage(v);
+    sqlite3ExprCacheAffinityChange(pParse, iRowidReg, 1);
+    sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
+    VdbeComment((v, "pk"));
+    pLevel->op = OP_Noop;
+  }else if( (pLoop->wsFlags & WHERE_IPK)!=0
+         && (pLoop->wsFlags & WHERE_COLUMN_RANGE)!=0
+  ){
+    /* Case 3:  We have an inequality comparison against the ROWID field.
+    */
+    int testOp = OP_Noop;
+    int start;
+    int memEndValue = 0;
+    WhereTerm *pStart, *pEnd;
+
+    assert( omitTable==0 );
+    j = 0;
+    pStart = pEnd = 0;
+    if( pLoop->wsFlags & WHERE_BTM_LIMIT ) pStart = pLoop->aLTerm[j++];
+    if( pLoop->wsFlags & WHERE_TOP_LIMIT ) pEnd = pLoop->aLTerm[j++];
+    assert( pStart!=0 || pEnd!=0 );
+    if( bRev ){
+      pTerm = pStart;
+      pStart = pEnd;
+      pEnd = pTerm;
+    }
+    codeCursorHint(pTabItem, pWInfo, pLevel, pEnd);
+    if( pStart ){
+      Expr *pX;             /* The expression that defines the start bound */
+      int r1, rTemp;        /* Registers for holding the start boundary */
+      int op;               /* Cursor seek operation */
+
+      /* The following constant maps TK_xx codes into corresponding 
+      ** seek opcodes.  It depends on a particular ordering of TK_xx
+      */
+      const u8 aMoveOp[] = {
+           /* TK_GT */  OP_SeekGT,
+           /* TK_LE */  OP_SeekLE,
+           /* TK_LT */  OP_SeekLT,
+           /* TK_GE */  OP_SeekGE
+      };
+      assert( TK_LE==TK_GT+1 );      /* Make sure the ordering.. */
+      assert( TK_LT==TK_GT+2 );      /*  ... of the TK_xx values... */
+      assert( TK_GE==TK_GT+3 );      /*  ... is correcct. */
+
+      assert( (pStart->wtFlags & TERM_VNULL)==0 );
+      testcase( pStart->wtFlags & TERM_VIRTUAL );
+      pX = pStart->pExpr;
+      assert( pX!=0 );
+      testcase( pStart->leftCursor!=iCur ); /* transitive constraints */
+      if( sqlite3ExprIsVector(pX->pRight) ){
+        r1 = rTemp = sqlite3GetTempReg(pParse);
+        codeExprOrVector(pParse, pX->pRight, r1, 1);
+        op = aMoveOp[(pX->op - TK_GT) | 0x0001];
+      }else{
+        r1 = sqlite3ExprCodeTemp(pParse, pX->pRight, &rTemp);
+        disableTerm(pLevel, pStart);
+        op = aMoveOp[(pX->op - TK_GT)];
+      }
+      sqlite3VdbeAddOp3(v, op, iCur, addrBrk, r1);
+      VdbeComment((v, "pk"));
+      VdbeCoverageIf(v, pX->op==TK_GT);
+      VdbeCoverageIf(v, pX->op==TK_LE);
+      VdbeCoverageIf(v, pX->op==TK_LT);
+      VdbeCoverageIf(v, pX->op==TK_GE);
+      sqlite3ExprCacheAffinityChange(pParse, r1, 1);
+      sqlite3ReleaseTempReg(pParse, rTemp);
+    }else{
+      sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iCur, addrBrk);
+      VdbeCoverageIf(v, bRev==0);
+      VdbeCoverageIf(v, bRev!=0);
+    }
+    if( pEnd ){
+      Expr *pX;
+      pX = pEnd->pExpr;
+      assert( pX!=0 );
+      assert( (pEnd->wtFlags & TERM_VNULL)==0 );
+      testcase( pEnd->leftCursor!=iCur ); /* Transitive constraints */
+      testcase( pEnd->wtFlags & TERM_VIRTUAL );
+      memEndValue = ++pParse->nMem;
+      codeExprOrVector(pParse, pX->pRight, memEndValue, 1);
+      if( 0==sqlite3ExprIsVector(pX->pRight) 
+       && (pX->op==TK_LT || pX->op==TK_GT) 
+      ){
+        testOp = bRev ? OP_Le : OP_Ge;
+      }else{
+        testOp = bRev ? OP_Lt : OP_Gt;
+      }
+      if( 0==sqlite3ExprIsVector(pX->pRight) ){
+        disableTerm(pLevel, pEnd);
+      }
+    }
+    start = sqlite3VdbeCurrentAddr(v);
+    pLevel->op = bRev ? OP_Prev : OP_Next;
+    pLevel->p1 = iCur;
+    pLevel->p2 = start;
+    assert( pLevel->p5==0 );
+    if( testOp!=OP_Noop ){
+      iRowidReg = ++pParse->nMem;
+      sqlite3VdbeAddOp2(v, OP_Rowid, iCur, iRowidReg);
+      sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
+      sqlite3VdbeAddOp3(v, testOp, memEndValue, addrBrk, iRowidReg);
+      VdbeCoverageIf(v, testOp==OP_Le);
+      VdbeCoverageIf(v, testOp==OP_Lt);
+      VdbeCoverageIf(v, testOp==OP_Ge);
+      VdbeCoverageIf(v, testOp==OP_Gt);
+      sqlite3VdbeChangeP5(v, SQLITE_AFF_NUMERIC | SQLITE_JUMPIFNULL);
+    }
+  }else if( pLoop->wsFlags & WHERE_INDEXED ){
+    /* Case 4: A scan using an index.
+    **
+    **         The WHERE clause may contain zero or more equality 
+    **         terms ("==" or "IN" operators) that refer to the N
+    **         left-most columns of the index. It may also contain
+    **         inequality constraints (>, <, >= or <=) on the indexed
+    **         column that immediately follows the N equalities. Only 
+    **         the right-most column can be an inequality - the rest must
+    **         use the "==" and "IN" operators. For example, if the 
+    **         index is on (x,y,z), then the following clauses are all 
+    **         optimized:
+    **
+    **            x=5
+    **            x=5 AND y=10
+    **            x=5 AND y<10
+    **            x=5 AND y>5 AND y<10
+    **            x=5 AND y=5 AND z<=10
+    **
+    **         The z<10 term of the following cannot be used, only
+    **         the x=5 term:
+    **
+    **            x=5 AND z<10
+    **
+    **         N may be zero if there are inequality constraints.
+    **         If there are no inequality constraints, then N is at
+    **         least one.
+    **
+    **         This case is also used when there are no WHERE clause
+    **         constraints but an index is selected anyway, in order
+    **         to force the output order to conform to an ORDER BY.
+    */  
+    static const u8 aStartOp[] = {
+      0,
+      0,
+      OP_Rewind,           /* 2: (!start_constraints && startEq &&  !bRev) */
+      OP_Last,             /* 3: (!start_constraints && startEq &&   bRev) */
+      OP_SeekGT,           /* 4: (start_constraints  && !startEq && !bRev) */
+      OP_SeekLT,           /* 5: (start_constraints  && !startEq &&  bRev) */
+      OP_SeekGE,           /* 6: (start_constraints  &&  startEq && !bRev) */
+      OP_SeekLE            /* 7: (start_constraints  &&  startEq &&  bRev) */
+    };
+    static const u8 aEndOp[] = {
+      OP_IdxGE,            /* 0: (end_constraints && !bRev && !endEq) */
+      OP_IdxGT,            /* 1: (end_constraints && !bRev &&  endEq) */
+      OP_IdxLE,            /* 2: (end_constraints &&  bRev && !endEq) */
+      OP_IdxLT,            /* 3: (end_constraints &&  bRev &&  endEq) */
+    };
+    u16 nEq = pLoop->u.btree.nEq;     /* Number of == or IN terms */
+    u16 nBtm = pLoop->u.btree.nBtm;   /* Length of BTM vector */
+    u16 nTop = pLoop->u.btree.nTop;   /* Length of TOP vector */
+    int regBase;                 /* Base register holding constraint values */
+    WhereTerm *pRangeStart = 0;  /* Inequality constraint at range start */
+    WhereTerm *pRangeEnd = 0;    /* Inequality constraint at range end */
+    int startEq;                 /* True if range start uses ==, >= or <= */
+    int endEq;                   /* True if range end uses ==, >= or <= */
+    int start_constraints;       /* Start of range is constrained */
+    int nConstraint;             /* Number of constraint terms */
+    Index *pIdx;                 /* The index we will be using */
+    int iIdxCur;                 /* The VDBE cursor for the index */
+    int nExtraReg = 0;           /* Number of extra registers needed */
+    int op;                      /* Instruction opcode */
+    char *zStartAff;             /* Affinity for start of range constraint */
+    char *zEndAff = 0;           /* Affinity for end of range constraint */
+    u8 bSeekPastNull = 0;        /* True to seek past initial nulls */
+    u8 bStopAtNull = 0;          /* Add condition to terminate at NULLs */
+
+    pIdx = pLoop->u.btree.pIndex;
+    iIdxCur = pLevel->iIdxCur;
+    assert( nEq>=pLoop->nSkip );
+
+    /* If this loop satisfies a sort order (pOrderBy) request that 
+    ** was passed to this function to implement a "SELECT min(x) ..." 
+    ** query, then the caller will only allow the loop to run for
+    ** a single iteration. This means that the first row returned
+    ** should not have a NULL value stored in 'x'. If column 'x' is
+    ** the first one after the nEq equality constraints in the index,
+    ** this requires some special handling.
+    */
+    assert( pWInfo->pOrderBy==0
+         || pWInfo->pOrderBy->nExpr==1
+         || (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)==0 );
+    if( (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)!=0
+     && pWInfo->nOBSat>0
+     && (pIdx->nKeyCol>nEq)
+    ){
+      assert( pLoop->nSkip==0 );
+      bSeekPastNull = 1;
+      nExtraReg = 1;
+    }
+
+    /* Find any inequality constraint terms for the start and end 
+    ** of the range. 
+    */
+    j = nEq;
+    if( pLoop->wsFlags & WHERE_BTM_LIMIT ){
+      pRangeStart = pLoop->aLTerm[j++];
+      nExtraReg = MAX(nExtraReg, pLoop->u.btree.nBtm);
+      /* Like optimization range constraints always occur in pairs */
+      assert( (pRangeStart->wtFlags & TERM_LIKEOPT)==0 || 
+              (pLoop->wsFlags & WHERE_TOP_LIMIT)!=0 );
+    }
+    if( pLoop->wsFlags & WHERE_TOP_LIMIT ){
+      pRangeEnd = pLoop->aLTerm[j++];
+      nExtraReg = MAX(nExtraReg, pLoop->u.btree.nTop);
+#ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
+      if( (pRangeEnd->wtFlags & TERM_LIKEOPT)!=0 ){
+        assert( pRangeStart!=0 );                     /* LIKE opt constraints */
+        assert( pRangeStart->wtFlags & TERM_LIKEOPT );   /* occur in pairs */
+        pLevel->iLikeRepCntr = (u32)++pParse->nMem;
+        sqlite3VdbeAddOp2(v, OP_Integer, 1, (int)pLevel->iLikeRepCntr);
+        VdbeComment((v, "LIKE loop counter"));
+        pLevel->addrLikeRep = sqlite3VdbeCurrentAddr(v);
+        /* iLikeRepCntr actually stores 2x the counter register number.  The
+        ** bottom bit indicates whether the search order is ASC or DESC. */
+        testcase( bRev );
+        testcase( pIdx->aSortOrder[nEq]==SQLITE_SO_DESC );
+        assert( (bRev & ~1)==0 );
+        pLevel->iLikeRepCntr <<=1;
+        pLevel->iLikeRepCntr |= bRev ^ (pIdx->aSortOrder[nEq]==SQLITE_SO_DESC);
+      }
+#endif
+      if( pRangeStart==0 ){
+        j = pIdx->aiColumn[nEq];
+        if( (j>=0 && pIdx->pTable->aCol[j].notNull==0) || j==XN_EXPR ){
+          bSeekPastNull = 1;
+        }
+      }
+    }
+    assert( pRangeEnd==0 || (pRangeEnd->wtFlags & TERM_VNULL)==0 );
+
+    /* If we are doing a reverse order scan on an ascending index, or
+    ** a forward order scan on a descending index, interchange the 
+    ** start and end terms (pRangeStart and pRangeEnd).
+    */
+    if( (nEq<pIdx->nKeyCol && bRev==(pIdx->aSortOrder[nEq]==SQLITE_SO_ASC))
+     || (bRev && pIdx->nKeyCol==nEq)
+    ){
+      SWAP(WhereTerm *, pRangeEnd, pRangeStart);
+      SWAP(u8, bSeekPastNull, bStopAtNull);
+      SWAP(u8, nBtm, nTop);
+    }
+
+    /* Generate code to evaluate all constraint terms using == or IN
+    ** and store the values of those terms in an array of registers
+    ** starting at regBase.
+    */
+    codeCursorHint(pTabItem, pWInfo, pLevel, pRangeEnd);
+    regBase = codeAllEqualityTerms(pParse,pLevel,bRev,nExtraReg,&zStartAff);
+    assert( zStartAff==0 || sqlite3Strlen30(zStartAff)>=nEq );
+    if( zStartAff && nTop ){
+      zEndAff = sqlite3DbStrDup(db, &zStartAff[nEq]);
+    }
+    addrNxt = pLevel->addrNxt;
+
+    testcase( pRangeStart && (pRangeStart->eOperator & WO_LE)!=0 );
+    testcase( pRangeStart && (pRangeStart->eOperator & WO_GE)!=0 );
+    testcase( pRangeEnd && (pRangeEnd->eOperator & WO_LE)!=0 );
+    testcase( pRangeEnd && (pRangeEnd->eOperator & WO_GE)!=0 );
+    startEq = !pRangeStart || pRangeStart->eOperator & (WO_LE|WO_GE);
+    endEq =   !pRangeEnd || pRangeEnd->eOperator & (WO_LE|WO_GE);
+    start_constraints = pRangeStart || nEq>0;
+
+    /* Seek the index cursor to the start of the range. */
+    nConstraint = nEq;
+    if( pRangeStart ){
+      Expr *pRight = pRangeStart->pExpr->pRight;
+      codeExprOrVector(pParse, pRight, regBase+nEq, nBtm);
+      whereLikeOptimizationStringFixup(v, pLevel, pRangeStart);
+      if( (pRangeStart->wtFlags & TERM_VNULL)==0
+       && sqlite3ExprCanBeNull(pRight)
+      ){
+        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
+        VdbeCoverage(v);
+      }
+      if( zStartAff ){
+        updateRangeAffinityStr(pRight, nBtm, &zStartAff[nEq]);
+      }  
+      nConstraint += nBtm;
+      testcase( pRangeStart->wtFlags & TERM_VIRTUAL );
+      if( sqlite3ExprIsVector(pRight)==0 ){
+        disableTerm(pLevel, pRangeStart);
+      }else{
+        startEq = 1;
+      }
+      bSeekPastNull = 0;
+    }else if( bSeekPastNull ){
+      sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
+      nConstraint++;
+      startEq = 0;
+      start_constraints = 1;
+    }
+    codeApplyAffinity(pParse, regBase, nConstraint - bSeekPastNull, zStartAff);
+    if( pLoop->nSkip>0 && nConstraint==pLoop->nSkip ){
+      /* The skip-scan logic inside the call to codeAllEqualityConstraints()
+      ** above has already left the cursor sitting on the correct row,
+      ** so no further seeking is needed */
+    }else{
+      op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev];
+      assert( op!=0 );
+      sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
+      VdbeCoverage(v);
+      VdbeCoverageIf(v, op==OP_Rewind);  testcase( op==OP_Rewind );
+      VdbeCoverageIf(v, op==OP_Last);    testcase( op==OP_Last );
+      VdbeCoverageIf(v, op==OP_SeekGT);  testcase( op==OP_SeekGT );
+      VdbeCoverageIf(v, op==OP_SeekGE);  testcase( op==OP_SeekGE );
+      VdbeCoverageIf(v, op==OP_SeekLE);  testcase( op==OP_SeekLE );
+      VdbeCoverageIf(v, op==OP_SeekLT);  testcase( op==OP_SeekLT );
+    }
+
+    /* Load the value for the inequality constraint at the end of the
+    ** range (if any).
+    */
+    nConstraint = nEq;
+    if( pRangeEnd ){
+      Expr *pRight = pRangeEnd->pExpr->pRight;
+      sqlite3ExprCacheRemove(pParse, regBase+nEq, 1);
+      codeExprOrVector(pParse, pRight, regBase+nEq, nTop);
+      whereLikeOptimizationStringFixup(v, pLevel, pRangeEnd);
+      if( (pRangeEnd->wtFlags & TERM_VNULL)==0
+       && sqlite3ExprCanBeNull(pRight)
+      ){
+        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
+        VdbeCoverage(v);
+      }
+      if( zEndAff ){
+        updateRangeAffinityStr(pRight, nTop, zEndAff);
+        codeApplyAffinity(pParse, regBase+nEq, nTop, zEndAff);
+      }else{
+        assert( pParse->db->mallocFailed );
+      }
+      nConstraint += nTop;
+      testcase( pRangeEnd->wtFlags & TERM_VIRTUAL );
+
+      if( sqlite3ExprIsVector(pRight)==0 ){
+        disableTerm(pLevel, pRangeEnd);
+      }else{
+        endEq = 1;
+      }
+    }else if( bStopAtNull ){
+      sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
+      endEq = 0;
+      nConstraint++;
+    }
+    sqlite3DbFree(db, zStartAff);
+    sqlite3DbFree(db, zEndAff);
+
+    /* Top of the loop body */
+    pLevel->p2 = sqlite3VdbeCurrentAddr(v);
+
+    /* Check if the index cursor is past the end of the range. */
+    if( nConstraint ){
+      op = aEndOp[bRev*2 + endEq];
+      sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
+      testcase( op==OP_IdxGT );  VdbeCoverageIf(v, op==OP_IdxGT );
+      testcase( op==OP_IdxGE );  VdbeCoverageIf(v, op==OP_IdxGE );
+      testcase( op==OP_IdxLT );  VdbeCoverageIf(v, op==OP_IdxLT );
+      testcase( op==OP_IdxLE );  VdbeCoverageIf(v, op==OP_IdxLE );
+    }
+
+    /* Seek the table cursor, if required */
+    if( omitTable ){
+      /* pIdx is a covering index.  No need to access the main table. */
+    }else if( HasRowid(pIdx->pTable) ){
+      if( (pWInfo->wctrlFlags & WHERE_SEEK_TABLE)!=0 ){
+        iRowidReg = ++pParse->nMem;
+        sqlite3VdbeAddOp2(v, OP_IdxRowid, iIdxCur, iRowidReg);
+        sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
+        sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, iRowidReg);
+        VdbeCoverage(v);
+      }else{
+        codeDeferredSeek(pWInfo, pIdx, iCur, iIdxCur);
+      }
+    }else if( iCur!=iIdxCur ){
+      Index *pPk = sqlite3PrimaryKeyIndex(pIdx->pTable);
+      iRowidReg = sqlite3GetTempRange(pParse, pPk->nKeyCol);
+      for(j=0; j<pPk->nKeyCol; j++){
+        k = sqlite3ColumnOfIndex(pIdx, pPk->aiColumn[j]);
+        sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, k, iRowidReg+j);
+      }
+      sqlite3VdbeAddOp4Int(v, OP_NotFound, iCur, addrCont,
+                           iRowidReg, pPk->nKeyCol); VdbeCoverage(v);
+    }
+
+    /* Record the instruction used to terminate the loop. */
+    if( pLoop->wsFlags & WHERE_ONEROW ){
+      pLevel->op = OP_Noop;
+    }else if( bRev ){
+      pLevel->op = OP_Prev;
+    }else{
+      pLevel->op = OP_Next;
+    }
+    pLevel->p1 = iIdxCur;
+    pLevel->p3 = (pLoop->wsFlags&WHERE_UNQ_WANTED)!=0 ? 1:0;
+    if( (pLoop->wsFlags & WHERE_CONSTRAINT)==0 ){
+      pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
+    }else{
+      assert( pLevel->p5==0 );
+    }
+  }else
+
+#ifndef SQLITE_OMIT_OR_OPTIMIZATION
+  if( pLoop->wsFlags & WHERE_MULTI_OR ){
+    /* Case 5:  Two or more separately indexed terms connected by OR
+    **
+    ** Example:
+    **
+    **   CREATE TABLE t1(a,b,c,d);
+    **   CREATE INDEX i1 ON t1(a);
+    **   CREATE INDEX i2 ON t1(b);
+    **   CREATE INDEX i3 ON t1(c);
+    **
+    **   SELECT * FROM t1 WHERE a=5 OR b=7 OR (c=11 AND d=13)
+    **
+    ** In the example, there are three indexed terms connected by OR.
+    ** The top of the loop looks like this:
+    **
+    **          Null       1                # Zero the rowset in reg 1
+    **
+    ** Then, for each indexed term, the following. The arguments to
+    ** RowSetTest are such that the rowid of the current row is inserted
+    ** into the RowSet. If it is already present, control skips the
+    ** Gosub opcode and jumps straight to the code generated by WhereEnd().
+    **
+    **        sqlite3WhereBegin(<term>)
+    **          RowSetTest                  # Insert rowid into rowset
+    **          Gosub      2 A
+    **        sqlite3WhereEnd()
+    **
+    ** Following the above, code to terminate the loop. Label A, the target
+    ** of the Gosub above, jumps to the instruction right after the Goto.
+    **
+    **          Null       1                # Zero the rowset in reg 1
+    **          Goto       B                # The loop is finished.
+    **
+    **       A: <loop body>                 # Return data, whatever.
+    **
+    **          Return     2                # Jump back to the Gosub
+    **
+    **       B: <after the loop>
+    **
+    ** Added 2014-05-26: If the table is a WITHOUT ROWID table, then
+    ** use an ephemeral index instead of a RowSet to record the primary
+    ** keys of the rows we have already seen.
+    **
+    */
+    WhereClause *pOrWc;    /* The OR-clause broken out into subterms */
+    SrcList *pOrTab;       /* Shortened table list or OR-clause generation */
+    Index *pCov = 0;             /* Potential covering index (or NULL) */
+    int iCovCur = pParse->nTab++;  /* Cursor used for index scans (if any) */
+
+    int regReturn = ++pParse->nMem;           /* Register used with OP_Gosub */
+    int regRowset = 0;                        /* Register for RowSet object */
+    int regRowid = 0;                         /* Register holding rowid */
+    int iLoopBody = sqlite3VdbeMakeLabel(v);  /* Start of loop body */
+    int iRetInit;                             /* Address of regReturn init */
+    int untestedTerms = 0;             /* Some terms not completely tested */
+    int ii;                            /* Loop counter */
+    u16 wctrlFlags;                    /* Flags for sub-WHERE clause */
+    Expr *pAndExpr = 0;                /* An ".. AND (...)" expression */
+    Table *pTab = pTabItem->pTab;
+
+    pTerm = pLoop->aLTerm[0];
+    assert( pTerm!=0 );
+    assert( pTerm->eOperator & WO_OR );
+    assert( (pTerm->wtFlags & TERM_ORINFO)!=0 );
+    pOrWc = &pTerm->u.pOrInfo->wc;
+    pLevel->op = OP_Return;
+    pLevel->p1 = regReturn;
+
+    /* Set up a new SrcList in pOrTab containing the table being scanned
+    ** by this loop in the a[0] slot and all notReady tables in a[1..] slots.
+    ** This becomes the SrcList in the recursive call to sqlite3WhereBegin().
+    */
+    if( pWInfo->nLevel>1 ){
+      int nNotReady;                 /* The number of notReady tables */
+      struct SrcList_item *origSrc;     /* Original list of tables */
+      nNotReady = pWInfo->nLevel - iLevel - 1;
+      pOrTab = sqlite3StackAllocRaw(db,
+                            sizeof(*pOrTab)+ nNotReady*sizeof(pOrTab->a[0]));
+      if( pOrTab==0 ) return notReady;
+      pOrTab->nAlloc = (u8)(nNotReady + 1);
+      pOrTab->nSrc = pOrTab->nAlloc;
+      memcpy(pOrTab->a, pTabItem, sizeof(*pTabItem));
+      origSrc = pWInfo->pTabList->a;
+      for(k=1; k<=nNotReady; k++){
+        memcpy(&pOrTab->a[k], &origSrc[pLevel[k].iFrom], sizeof(pOrTab->a[k]));
+      }
+    }else{
+      pOrTab = pWInfo->pTabList;
+    }
+
+    /* Initialize the rowset register to contain NULL. An SQL NULL is 
+    ** equivalent to an empty rowset.  Or, create an ephemeral index
+    ** capable of holding primary keys in the case of a WITHOUT ROWID.
+    **
+    ** Also initialize regReturn to contain the address of the instruction 
+    ** immediately following the OP_Return at the bottom of the loop. This
+    ** is required in a few obscure LEFT JOIN cases where control jumps
+    ** over the top of the loop into the body of it. In this case the 
+    ** correct response for the end-of-loop code (the OP_Return) is to 
+    ** fall through to the next instruction, just as an OP_Next does if
+    ** called on an uninitialized cursor.
+    */
+    if( (pWInfo->wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
+      if( HasRowid(pTab) ){
+        regRowset = ++pParse->nMem;
+        sqlite3VdbeAddOp2(v, OP_Null, 0, regRowset);
+      }else{
+        Index *pPk = sqlite3PrimaryKeyIndex(pTab);
+        regRowset = pParse->nTab++;
+        sqlite3VdbeAddOp2(v, OP_OpenEphemeral, regRowset, pPk->nKeyCol);
+        sqlite3VdbeSetP4KeyInfo(pParse, pPk);
+      }
+      regRowid = ++pParse->nMem;
+    }
+    iRetInit = sqlite3VdbeAddOp2(v, OP_Integer, 0, regReturn);
+
+    /* If the original WHERE clause is z of the form:  (x1 OR x2 OR ...) AND y
+    ** Then for every term xN, evaluate as the subexpression: xN AND z
+    ** That way, terms in y that are factored into the disjunction will
+    ** be picked up by the recursive calls to sqlite3WhereBegin() below.
+    **
+    ** Actually, each subexpression is converted to "xN AND w" where w is
+    ** the "interesting" terms of z - terms that did not originate in the
+    ** ON or USING clause of a LEFT JOIN, and terms that are usable as 
+    ** indices.
+    **
+    ** This optimization also only applies if the (x1 OR x2 OR ...) term
+    ** is not contained in the ON clause of a LEFT JOIN.
+    ** See ticket http://www.sqlite.org/src/info/f2369304e4
+    */
+    if( pWC->nTerm>1 ){
+      int iTerm;
+      for(iTerm=0; iTerm<pWC->nTerm; iTerm++){
+        Expr *pExpr = pWC->a[iTerm].pExpr;
+        if( &pWC->a[iTerm] == pTerm ) continue;
+        if( ExprHasProperty(pExpr, EP_FromJoin) ) continue;
+        testcase( pWC->a[iTerm].wtFlags & TERM_VIRTUAL );
+        testcase( pWC->a[iTerm].wtFlags & TERM_CODED );
+        if( (pWC->a[iTerm].wtFlags & (TERM_VIRTUAL|TERM_CODED))!=0 ) continue;
+        if( (pWC->a[iTerm].eOperator & WO_ALL)==0 ) continue;
+        testcase( pWC->a[iTerm].wtFlags & TERM_ORINFO );
+        pExpr = sqlite3ExprDup(db, pExpr, 0);
+        pAndExpr = sqlite3ExprAnd(db, pAndExpr, pExpr);
+      }
+      if( pAndExpr ){
+        pAndExpr = sqlite3PExpr(pParse, TK_AND|TKFLG_DONTFOLD, 0, pAndExpr, 0);
+      }
+    }
+
+    /* Run a separate WHERE clause for each term of the OR clause.  After
+    ** eliminating duplicates from other WHERE clauses, the action for each
+    ** sub-WHERE clause is to to invoke the main loop body as a subroutine.
+    */
+    wctrlFlags =  WHERE_OR_SUBCLAUSE | (pWInfo->wctrlFlags & WHERE_SEEK_TABLE);
+    for(ii=0; ii<pOrWc->nTerm; ii++){
+      WhereTerm *pOrTerm = &pOrWc->a[ii];
+      if( pOrTerm->leftCursor==iCur || (pOrTerm->eOperator & WO_AND)!=0 ){
+        WhereInfo *pSubWInfo;           /* Info for single OR-term scan */
+        Expr *pOrExpr = pOrTerm->pExpr; /* Current OR clause term */
+        int jmp1 = 0;                   /* Address of jump operation */
+        if( pAndExpr && !ExprHasProperty(pOrExpr, EP_FromJoin) ){
+          pAndExpr->pLeft = pOrExpr;
+          pOrExpr = pAndExpr;
+        }
+        /* Loop through table entries that match term pOrTerm. */
+        WHERETRACE(0xffff, ("Subplan for OR-clause:\n"));
+        pSubWInfo = sqlite3WhereBegin(pParse, pOrTab, pOrExpr, 0, 0,
+                                      wctrlFlags, iCovCur);
+        assert( pSubWInfo || pParse->nErr || db->mallocFailed );
+        if( pSubWInfo ){
+          WhereLoop *pSubLoop;
+          int addrExplain = sqlite3WhereExplainOneScan(
+              pParse, pOrTab, &pSubWInfo->a[0], iLevel, pLevel->iFrom, 0
+          );
+          sqlite3WhereAddScanStatus(v, pOrTab, &pSubWInfo->a[0], addrExplain);
+
+          /* This is the sub-WHERE clause body.  First skip over
+          ** duplicate rows from prior sub-WHERE clauses, and record the
+          ** rowid (or PRIMARY KEY) for the current row so that the same
+          ** row will be skipped in subsequent sub-WHERE clauses.
+          */
+          if( (pWInfo->wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
+            int r;
+            int iSet = ((ii==pOrWc->nTerm-1)?-1:ii);
+            if( HasRowid(pTab) ){
+              r = sqlite3ExprCodeGetColumn(pParse, pTab, -1, iCur, regRowid, 0);
+              jmp1 = sqlite3VdbeAddOp4Int(v, OP_RowSetTest, regRowset, 0,
+                                           r,iSet);
+              VdbeCoverage(v);
+            }else{
+              Index *pPk = sqlite3PrimaryKeyIndex(pTab);
+              int nPk = pPk->nKeyCol;
+              int iPk;
+
+              /* Read the PK into an array of temp registers. */
+              r = sqlite3GetTempRange(pParse, nPk);
+              for(iPk=0; iPk<nPk; iPk++){
+                int iCol = pPk->aiColumn[iPk];
+                sqlite3ExprCodeGetColumnToReg(pParse, pTab, iCol, iCur, r+iPk);
+              }
+
+              /* Check if the temp table already contains this key. If so,
+              ** the row has already been included in the result set and
+              ** can be ignored (by jumping past the Gosub below). Otherwise,
+              ** insert the key into the temp table and proceed with processing
+              ** the row.
+              **
+              ** Use some of the same optimizations as OP_RowSetTest: If iSet
+              ** is zero, assume that the key cannot already be present in
+              ** the temp table. And if iSet is -1, assume that there is no 
+              ** need to insert the key into the temp table, as it will never 
+              ** be tested for.  */ 
+              if( iSet ){
+                jmp1 = sqlite3VdbeAddOp4Int(v, OP_Found, regRowset, 0, r, nPk);
+                VdbeCoverage(v);
+              }
+              if( iSet>=0 ){
+                sqlite3VdbeAddOp3(v, OP_MakeRecord, r, nPk, regRowid);
+                sqlite3VdbeAddOp3(v, OP_IdxInsert, regRowset, regRowid, 0);
+                if( iSet ) sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
+              }
+
+              /* Release the array of temp registers */
+              sqlite3ReleaseTempRange(pParse, r, nPk);
+            }
+          }
+
+          /* Invoke the main loop body as a subroutine */
+          sqlite3VdbeAddOp2(v, OP_Gosub, regReturn, iLoopBody);
+
+          /* Jump here (skipping the main loop body subroutine) if the
+          ** current sub-WHERE row is a duplicate from prior sub-WHEREs. */
+          if( jmp1 ) sqlite3VdbeJumpHere(v, jmp1);
+
+          /* The pSubWInfo->untestedTerms flag means that this OR term
+          ** contained one or more AND term from a notReady table.  The
+          ** terms from the notReady table could not be tested and will
+          ** need to be tested later.
+          */
+          if( pSubWInfo->untestedTerms ) untestedTerms = 1;
+
+          /* If all of the OR-connected terms are optimized using the same
+          ** index, and the index is opened using the same cursor number
+          ** by each call to sqlite3WhereBegin() made by this loop, it may
+          ** be possible to use that index as a covering index.
+          **
+          ** If the call to sqlite3WhereBegin() above resulted in a scan that
+          ** uses an index, and this is either the first OR-connected term
+          ** processed or the index is the same as that used by all previous
+          ** terms, set pCov to the candidate covering index. Otherwise, set 
+          ** pCov to NULL to indicate that no candidate covering index will 
+          ** be available.
+          */
+          pSubLoop = pSubWInfo->a[0].pWLoop;
+          assert( (pSubLoop->wsFlags & WHERE_AUTO_INDEX)==0 );
+          if( (pSubLoop->wsFlags & WHERE_INDEXED)!=0
+           && (ii==0 || pSubLoop->u.btree.pIndex==pCov)
+           && (HasRowid(pTab) || !IsPrimaryKeyIndex(pSubLoop->u.btree.pIndex))
+          ){
+            assert( pSubWInfo->a[0].iIdxCur==iCovCur );
+            pCov = pSubLoop->u.btree.pIndex;
+          }else{
+            pCov = 0;
+          }
+
+          /* Finish the loop through table entries that match term pOrTerm. */
+          sqlite3WhereEnd(pSubWInfo);
+        }
+      }
+    }
+    pLevel->u.pCovidx = pCov;
+    if( pCov ) pLevel->iIdxCur = iCovCur;
+    if( pAndExpr ){
+      pAndExpr->pLeft = 0;
+      sqlite3ExprDelete(db, pAndExpr);
+    }
+    sqlite3VdbeChangeP1(v, iRetInit, sqlite3VdbeCurrentAddr(v));
+    sqlite3VdbeGoto(v, pLevel->addrBrk);
+    sqlite3VdbeResolveLabel(v, iLoopBody);
+
+    if( pWInfo->nLevel>1 ) sqlite3StackFree(db, pOrTab);
+    if( !untestedTerms ) disableTerm(pLevel, pTerm);
+  }else
+#endif /* SQLITE_OMIT_OR_OPTIMIZATION */
+
+  {
+    /* Case 6:  There is no usable index.  We must do a complete
+    **          scan of the entire table.
+    */
+    static const u8 aStep[] = { OP_Next, OP_Prev };
+    static const u8 aStart[] = { OP_Rewind, OP_Last };
+    assert( bRev==0 || bRev==1 );
+    if( pTabItem->fg.isRecursive ){
+      /* Tables marked isRecursive have only a single row that is stored in
+      ** a pseudo-cursor.  No need to Rewind or Next such cursors. */
+      pLevel->op = OP_Noop;
+    }else{
+      codeCursorHint(pTabItem, pWInfo, pLevel, 0);
+      pLevel->op = aStep[bRev];
+      pLevel->p1 = iCur;
+      pLevel->p2 = 1 + sqlite3VdbeAddOp2(v, aStart[bRev], iCur, addrBrk);
+      VdbeCoverageIf(v, bRev==0);
+      VdbeCoverageIf(v, bRev!=0);
+      pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
+    }
+  }
+
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+  pLevel->addrVisit = sqlite3VdbeCurrentAddr(v);
+#endif
+
+  /* Insert code to test every subexpression that can be completely
+  ** computed using the current set of tables.
+  */
+  for(pTerm=pWC->a, j=pWC->nTerm; j>0; j--, pTerm++){
+    Expr *pE;
+    int skipLikeAddr = 0;
+    testcase( pTerm->wtFlags & TERM_VIRTUAL );
+    testcase( pTerm->wtFlags & TERM_CODED );
+    if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
+    if( (pTerm->prereqAll & pLevel->notReady)!=0 ){
+      testcase( pWInfo->untestedTerms==0
+               && (pWInfo->wctrlFlags & WHERE_OR_SUBCLAUSE)!=0 );
+      pWInfo->untestedTerms = 1;
+      continue;
+    }
+    pE = pTerm->pExpr;
+    assert( pE!=0 );
+    if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){
+      continue;
+    }
+    if( pTerm->wtFlags & TERM_LIKECOND ){
+      /* If the TERM_LIKECOND flag is set, that means that the range search
+      ** is sufficient to guarantee that the LIKE operator is true, so we
+      ** can skip the call to the like(A,B) function.  But this only works
+      ** for strings.  So do not skip the call to the function on the pass
+      ** that compares BLOBs. */
+#ifdef SQLITE_LIKE_DOESNT_MATCH_BLOBS
+      continue;
+#else
+      u32 x = pLevel->iLikeRepCntr;
+      assert( x>0 );
+      skipLikeAddr = sqlite3VdbeAddOp1(v, (x&1)? OP_IfNot : OP_If, (int)(x>>1));
+      VdbeCoverage(v);
+#endif
+    }
+    sqlite3ExprIfFalse(pParse, pE, addrCont, SQLITE_JUMPIFNULL);
+    if( skipLikeAddr ) sqlite3VdbeJumpHere(v, skipLikeAddr);
+    pTerm->wtFlags |= TERM_CODED;
+  }
+
+  /* Insert code to test for implied constraints based on transitivity
+  ** of the "==" operator.
+  **
+  ** Example: If the WHERE clause contains "t1.a=t2.b" and "t2.b=123"
+  ** and we are coding the t1 loop and the t2 loop has not yet coded,
+  ** then we cannot use the "t1.a=t2.b" constraint, but we can code
+  ** the implied "t1.a=123" constraint.
+  */
+  for(pTerm=pWC->a, j=pWC->nTerm; j>0; j--, pTerm++){
+    Expr *pE, sEAlt;
+    WhereTerm *pAlt;
+    if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
+    if( (pTerm->eOperator & (WO_EQ|WO_IS))==0 ) continue;
+    if( (pTerm->eOperator & WO_EQUIV)==0 ) continue;
+    if( pTerm->leftCursor!=iCur ) continue;
+    if( pLevel->iLeftJoin ) continue;
+    pE = pTerm->pExpr;
+    assert( !ExprHasProperty(pE, EP_FromJoin) );
+    assert( (pTerm->prereqRight & pLevel->notReady)!=0 );
+    pAlt = sqlite3WhereFindTerm(pWC, iCur, pTerm->u.leftColumn, notReady,
+                    WO_EQ|WO_IN|WO_IS, 0);
+    if( pAlt==0 ) continue;
+    if( pAlt->wtFlags & (TERM_CODED) ) continue;
+    testcase( pAlt->eOperator & WO_EQ );
+    testcase( pAlt->eOperator & WO_IS );
+    testcase( pAlt->eOperator & WO_IN );
+    VdbeModuleComment((v, "begin transitive constraint"));
+    sEAlt = *pAlt->pExpr;
+    sEAlt.pLeft = pE->pLeft;
+    sqlite3ExprIfFalse(pParse, &sEAlt, addrCont, SQLITE_JUMPIFNULL);
+  }
+
+  /* For a LEFT OUTER JOIN, generate code that will record the fact that
+  ** at least one row of the right table has matched the left table.  
+  */
+  if( pLevel->iLeftJoin ){
+    pLevel->addrFirst = sqlite3VdbeCurrentAddr(v);
+    sqlite3VdbeAddOp2(v, OP_Integer, 1, pLevel->iLeftJoin);
+    VdbeComment((v, "record LEFT JOIN hit"));
+    sqlite3ExprCacheClear(pParse);
+    for(pTerm=pWC->a, j=0; j<pWC->nTerm; j++, pTerm++){
+      testcase( pTerm->wtFlags & TERM_VIRTUAL );
+      testcase( pTerm->wtFlags & TERM_CODED );
+      if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
+      if( (pTerm->prereqAll & pLevel->notReady)!=0 ){
+        assert( pWInfo->untestedTerms );
+        continue;
+      }
+      assert( pTerm->pExpr );
+      sqlite3ExprIfFalse(pParse, pTerm->pExpr, addrCont, SQLITE_JUMPIFNULL);
+      pTerm->wtFlags |= TERM_CODED;
+    }
+  }
+
+  return pLevel->notReady;
+}
+
+/************** End of wherecode.c *******************************************/
+/************** Begin file whereexpr.c ***************************************/
+/*
+** 2015-06-08
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This module contains C code that generates VDBE code used to process
+** the WHERE clause of SQL statements.
+**
+** This file was originally part of where.c but was split out to improve
+** readability and editabiliity.  This file contains utility routines for
+** analyzing Expr objects in the WHERE clause.
+*/
+/* #include "sqliteInt.h" */
+/* #include "whereInt.h" */
+
+/* Forward declarations */
+static void exprAnalyze(SrcList*, WhereClause*, int);
+
+/*
+** Deallocate all memory associated with a WhereOrInfo object.
+*/
+static void whereOrInfoDelete(sqlite3 *db, WhereOrInfo *p){
+  sqlite3WhereClauseClear(&p->wc);
+  sqlite3DbFree(db, p);
+}
+
+/*
+** Deallocate all memory associated with a WhereAndInfo object.
+*/
+static void whereAndInfoDelete(sqlite3 *db, WhereAndInfo *p){
+  sqlite3WhereClauseClear(&p->wc);
+  sqlite3DbFree(db, p);
+}
+
+/*
+** Add a single new WhereTerm entry to the WhereClause object pWC.
+** The new WhereTerm object is constructed from Expr p and with wtFlags.
+** The index in pWC->a[] of the new WhereTerm is returned on success.
+** 0 is returned if the new WhereTerm could not be added due to a memory
+** allocation error.  The memory allocation failure will be recorded in
+** the db->mallocFailed flag so that higher-level functions can detect it.
+**
+** This routine will increase the size of the pWC->a[] array as necessary.
+**
+** If the wtFlags argument includes TERM_DYNAMIC, then responsibility
+** for freeing the expression p is assumed by the WhereClause object pWC.
+** This is true even if this routine fails to allocate a new WhereTerm.
+**
+** WARNING:  This routine might reallocate the space used to store
+** WhereTerms.  All pointers to WhereTerms should be invalidated after
+** calling this routine.  Such pointers may be reinitialized by referencing
+** the pWC->a[] array.
+*/
+static int whereClauseInsert(WhereClause *pWC, Expr *p, u16 wtFlags){
+  WhereTerm *pTerm;
+  int idx;
+  testcase( wtFlags & TERM_VIRTUAL );
+  if( pWC->nTerm>=pWC->nSlot ){
+    WhereTerm *pOld = pWC->a;
+    sqlite3 *db = pWC->pWInfo->pParse->db;
+    pWC->a = sqlite3DbMallocRawNN(db, sizeof(pWC->a[0])*pWC->nSlot*2 );
+    if( pWC->a==0 ){
+      if( wtFlags & TERM_DYNAMIC ){
+        sqlite3ExprDelete(db, p);
+      }
+      pWC->a = pOld;
+      return 0;
+    }
+    memcpy(pWC->a, pOld, sizeof(pWC->a[0])*pWC->nTerm);
+    if( pOld!=pWC->aStatic ){
+      sqlite3DbFree(db, pOld);
+    }
+    pWC->nSlot = sqlite3DbMallocSize(db, pWC->a)/sizeof(pWC->a[0]);
+  }
+  pTerm = &pWC->a[idx = pWC->nTerm++];
+  if( p && ExprHasProperty(p, EP_Unlikely) ){
+    pTerm->truthProb = sqlite3LogEst(p->iTable) - 270;
+  }else{
+    pTerm->truthProb = 1;
+  }
+  pTerm->pExpr = sqlite3ExprSkipCollate(p);
+  pTerm->wtFlags = wtFlags;
+  pTerm->pWC = pWC;
+  pTerm->iParent = -1;
+  memset(&pTerm->eOperator, 0,
+         sizeof(WhereTerm) - offsetof(WhereTerm,eOperator));
+  return idx;
+}
+
+/*
+** Return TRUE if the given operator is one of the operators that is
+** allowed for an indexable WHERE clause term.  The allowed operators are
+** "=", "<", ">", "<=", ">=", "IN", "IS", and "IS NULL"
+*/
+static int allowedOp(int op){
+  assert( TK_GT>TK_EQ && TK_GT<TK_GE );
+  assert( TK_LT>TK_EQ && TK_LT<TK_GE );
+  assert( TK_LE>TK_EQ && TK_LE<TK_GE );
+  assert( TK_GE==TK_EQ+4 );
+  return op==TK_IN || (op>=TK_EQ && op<=TK_GE) || op==TK_ISNULL || op==TK_IS;
+}
+
+/*
+** Commute a comparison operator.  Expressions of the form "X op Y"
+** are converted into "Y op X".
+**
+** If left/right precedence rules come into play when determining the
+** collating sequence, then COLLATE operators are adjusted to ensure
+** that the collating sequence does not change.  For example:
+** "Y collate NOCASE op X" becomes "X op Y" because any collation sequence on
+** the left hand side of a comparison overrides any collation sequence 
+** attached to the right. For the same reason the EP_Collate flag
+** is not commuted.
+*/
+static void exprCommute(Parse *pParse, Expr *pExpr){
+  u16 expRight = (pExpr->pRight->flags & EP_Collate);
+  u16 expLeft = (pExpr->pLeft->flags & EP_Collate);
+  assert( allowedOp(pExpr->op) && pExpr->op!=TK_IN );
+  if( expRight==expLeft ){
+    /* Either X and Y both have COLLATE operator or neither do */
+    if( expRight ){
+      /* Both X and Y have COLLATE operators.  Make sure X is always
+      ** used by clearing the EP_Collate flag from Y. */
+      pExpr->pRight->flags &= ~EP_Collate;
+    }else if( sqlite3ExprCollSeq(pParse, pExpr->pLeft)!=0 ){
+      /* Neither X nor Y have COLLATE operators, but X has a non-default
+      ** collating sequence.  So add the EP_Collate marker on X to cause
+      ** it to be searched first. */
+      pExpr->pLeft->flags |= EP_Collate;
+    }
+  }
+  SWAP(Expr*,pExpr->pRight,pExpr->pLeft);
+  if( pExpr->op>=TK_GT ){
+    assert( TK_LT==TK_GT+2 );
+    assert( TK_GE==TK_LE+2 );
+    assert( TK_GT>TK_EQ );
+    assert( TK_GT<TK_LE );
+    assert( pExpr->op>=TK_GT && pExpr->op<=TK_GE );
+    pExpr->op = ((pExpr->op-TK_GT)^2)+TK_GT;
+  }
+}
+
+/*
+** Translate from TK_xx operator to WO_xx bitmask.
+*/
+static u16 operatorMask(int op){
+  u16 c;
+  assert( allowedOp(op) );
+  if( op==TK_IN ){
+    c = WO_IN;
+  }else if( op==TK_ISNULL ){
+    c = WO_ISNULL;
+  }else if( op==TK_IS ){
+    c = WO_IS;
+  }else{
+    assert( (WO_EQ<<(op-TK_EQ)) < 0x7fff );
+    c = (u16)(WO_EQ<<(op-TK_EQ));
+  }
+  assert( op!=TK_ISNULL || c==WO_ISNULL );
+  assert( op!=TK_IN || c==WO_IN );
+  assert( op!=TK_EQ || c==WO_EQ );
+  assert( op!=TK_LT || c==WO_LT );
+  assert( op!=TK_LE || c==WO_LE );
+  assert( op!=TK_GT || c==WO_GT );
+  assert( op!=TK_GE || c==WO_GE );
+  assert( op!=TK_IS || c==WO_IS );
+  return c;
+}
+
+
+#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
+/*
+** Check to see if the given expression is a LIKE or GLOB operator that
+** can be optimized using inequality constraints.  Return TRUE if it is
+** so and false if not.
+**
+** In order for the operator to be optimizible, the RHS must be a string
+** literal that does not begin with a wildcard.  The LHS must be a column
+** that may only be NULL, a string, or a BLOB, never a number. (This means
+** that virtual tables cannot participate in the LIKE optimization.)  The
+** collating sequence for the column on the LHS must be appropriate for
+** the operator.
+*/
+static int isLikeOrGlob(
+  Parse *pParse,    /* Parsing and code generating context */
+  Expr *pExpr,      /* Test this expression */
+  Expr **ppPrefix,  /* Pointer to TK_STRING expression with pattern prefix */
+  int *pisComplete, /* True if the only wildcard is % in the last character */
+  int *pnoCase      /* True if uppercase is equivalent to lowercase */
+){
+  const char *z = 0;         /* String on RHS of LIKE operator */
+  Expr *pRight, *pLeft;      /* Right and left size of LIKE operator */
+  ExprList *pList;           /* List of operands to the LIKE operator */
+  int c;                     /* One character in z[] */
+  int cnt;                   /* Number of non-wildcard prefix characters */
+  char wc[3];                /* Wildcard characters */
+  sqlite3 *db = pParse->db;  /* Database connection */
+  sqlite3_value *pVal = 0;
+  int op;                    /* Opcode of pRight */
+  int rc;                    /* Result code to return */
+
+  if( !sqlite3IsLikeFunction(db, pExpr, pnoCase, wc) ){
+    return 0;
+  }
+#ifdef SQLITE_EBCDIC
+  if( *pnoCase ) return 0;
+#endif
+  pList = pExpr->x.pList;
+  pLeft = pList->a[1].pExpr;
+  if( pLeft->op!=TK_COLUMN 
+   || sqlite3ExprAffinity(pLeft)!=SQLITE_AFF_TEXT 
+   || IsVirtual(pLeft->pTab)  /* Value might be numeric */
+  ){
+    /* IMP: R-02065-49465 The left-hand side of the LIKE or GLOB operator must
+    ** be the name of an indexed column with TEXT affinity. */
+    return 0;
+  }
+  assert( pLeft->iColumn!=(-1) ); /* Because IPK never has AFF_TEXT */
+
+  pRight = sqlite3ExprSkipCollate(pList->a[0].pExpr);
+  op = pRight->op;
+  if( op==TK_VARIABLE ){
+    Vdbe *pReprepare = pParse->pReprepare;
+    int iCol = pRight->iColumn;
+    pVal = sqlite3VdbeGetBoundValue(pReprepare, iCol, SQLITE_AFF_BLOB);
+    if( pVal && sqlite3_value_type(pVal)==SQLITE_TEXT ){
+      z = (char *)sqlite3_value_text(pVal);
+    }
+    sqlite3VdbeSetVarmask(pParse->pVdbe, iCol);
+    assert( pRight->op==TK_VARIABLE || pRight->op==TK_REGISTER );
+  }else if( op==TK_STRING ){
+    z = pRight->u.zToken;
+  }
+  if( z ){
+    cnt = 0;
+    while( (c=z[cnt])!=0 && c!=wc[0] && c!=wc[1] && c!=wc[2] ){
+      cnt++;
+    }
+    if( cnt!=0 && 255!=(u8)z[cnt-1] ){
+      Expr *pPrefix;
+      *pisComplete = c==wc[0] && z[cnt+1]==0;
+      pPrefix = sqlite3Expr(db, TK_STRING, z);
+      if( pPrefix ) pPrefix->u.zToken[cnt] = 0;
+      *ppPrefix = pPrefix;
+      if( op==TK_VARIABLE ){
+        Vdbe *v = pParse->pVdbe;
+        sqlite3VdbeSetVarmask(v, pRight->iColumn);
+        if( *pisComplete && pRight->u.zToken[1] ){
+          /* If the rhs of the LIKE expression is a variable, and the current
+          ** value of the variable means there is no need to invoke the LIKE
+          ** function, then no OP_Variable will be added to the program.
+          ** This causes problems for the sqlite3_bind_parameter_name()
+          ** API. To work around them, add a dummy OP_Variable here.
+          */ 
+          int r1 = sqlite3GetTempReg(pParse);
+          sqlite3ExprCodeTarget(pParse, pRight, r1);
+          sqlite3VdbeChangeP3(v, sqlite3VdbeCurrentAddr(v)-1, 0);
+          sqlite3ReleaseTempReg(pParse, r1);
+        }
+      }
+    }else{
+      z = 0;
+    }
+  }
+
+  rc = (z!=0);
+  sqlite3ValueFree(pVal);
+  return rc;
+}
+#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
+
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/*
+** Check to see if the given expression is of the form
+**
+**         column OP expr
+**
+** where OP is one of MATCH, GLOB, LIKE or REGEXP and "column" is a 
+** column of a virtual table.
+**
+** If it is then return TRUE.  If not, return FALSE.
+*/
+static int isMatchOfColumn(
+  Expr *pExpr,                    /* Test this expression */
+  unsigned char *peOp2            /* OUT: 0 for MATCH, or else an op2 value */
+){
+  static const struct Op2 {
+    const char *zOp;
+    unsigned char eOp2;
+  } aOp[] = {
+    { "match",  SQLITE_INDEX_CONSTRAINT_MATCH },
+    { "glob",   SQLITE_INDEX_CONSTRAINT_GLOB },
+    { "like",   SQLITE_INDEX_CONSTRAINT_LIKE },
+    { "regexp", SQLITE_INDEX_CONSTRAINT_REGEXP }
+  };
+  ExprList *pList;
+  Expr *pCol;                     /* Column reference */
+  int i;
+
+  if( pExpr->op!=TK_FUNCTION ){
+    return 0;
+  }
+  pList = pExpr->x.pList;
+  if( pList==0 || pList->nExpr!=2 ){
+    return 0;
+  }
+  pCol = pList->a[1].pExpr;
+  if( pCol->op!=TK_COLUMN || !IsVirtual(pCol->pTab) ){
+    return 0;
+  }
+  for(i=0; i<ArraySize(aOp); i++){
+    if( sqlite3StrICmp(pExpr->u.zToken, aOp[i].zOp)==0 ){
+      *peOp2 = aOp[i].eOp2;
+      return 1;
+    }
+  }
+  return 0;
+}
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+/*
+** If the pBase expression originated in the ON or USING clause of
+** a join, then transfer the appropriate markings over to derived.
+*/
+static void transferJoinMarkings(Expr *pDerived, Expr *pBase){
+  if( pDerived ){
+    pDerived->flags |= pBase->flags & EP_FromJoin;
+    pDerived->iRightJoinTable = pBase->iRightJoinTable;
+  }
+}
+
+/*
+** Mark term iChild as being a child of term iParent
+*/
+static void markTermAsChild(WhereClause *pWC, int iChild, int iParent){
+  pWC->a[iChild].iParent = iParent;
+  pWC->a[iChild].truthProb = pWC->a[iParent].truthProb;
+  pWC->a[iParent].nChild++;
+}
+
+/*
+** Return the N-th AND-connected subterm of pTerm.  Or if pTerm is not
+** a conjunction, then return just pTerm when N==0.  If N is exceeds
+** the number of available subterms, return NULL.
+*/
+static WhereTerm *whereNthSubterm(WhereTerm *pTerm, int N){
+  if( pTerm->eOperator!=WO_AND ){
+    return N==0 ? pTerm : 0;
+  }
+  if( N<pTerm->u.pAndInfo->wc.nTerm ){
+    return &pTerm->u.pAndInfo->wc.a[N];
+  }
+  return 0;
+}
+
+/*
+** Subterms pOne and pTwo are contained within WHERE clause pWC.  The
+** two subterms are in disjunction - they are OR-ed together.
+**
+** If these two terms are both of the form:  "A op B" with the same
+** A and B values but different operators and if the operators are
+** compatible (if one is = and the other is <, for example) then
+** add a new virtual AND term to pWC that is the combination of the
+** two.
+**
+** Some examples:
+**
+**    x<y OR x=y    -->     x<=y
+**    x=y OR x=y    -->     x=y
+**    x<=y OR x<y   -->     x<=y
+**
+** The following is NOT generated:
+**
+**    x<y OR x>y    -->     x!=y     
+*/
+static void whereCombineDisjuncts(
+  SrcList *pSrc,         /* the FROM clause */
+  WhereClause *pWC,      /* The complete WHERE clause */
+  WhereTerm *pOne,       /* First disjunct */
+  WhereTerm *pTwo        /* Second disjunct */
+){
+  u16 eOp = pOne->eOperator | pTwo->eOperator;
+  sqlite3 *db;           /* Database connection (for malloc) */
+  Expr *pNew;            /* New virtual expression */
+  int op;                /* Operator for the combined expression */
+  int idxNew;            /* Index in pWC of the next virtual term */
+
+  if( (pOne->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE))==0 ) return;
+  if( (pTwo->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE))==0 ) return;
+  if( (eOp & (WO_EQ|WO_LT|WO_LE))!=eOp
+   && (eOp & (WO_EQ|WO_GT|WO_GE))!=eOp ) return;
+  assert( pOne->pExpr->pLeft!=0 && pOne->pExpr->pRight!=0 );
+  assert( pTwo->pExpr->pLeft!=0 && pTwo->pExpr->pRight!=0 );
+  if( sqlite3ExprCompare(pOne->pExpr->pLeft, pTwo->pExpr->pLeft, -1) ) return;
+  if( sqlite3ExprCompare(pOne->pExpr->pRight, pTwo->pExpr->pRight, -1) )return;
+  /* If we reach this point, it means the two subterms can be combined */
+  if( (eOp & (eOp-1))!=0 ){
+    if( eOp & (WO_LT|WO_LE) ){
+      eOp = WO_LE;
+    }else{
+      assert( eOp & (WO_GT|WO_GE) );
+      eOp = WO_GE;
+    }
+  }
+  db = pWC->pWInfo->pParse->db;
+  pNew = sqlite3ExprDup(db, pOne->pExpr, 0);
+  if( pNew==0 ) return;
+  for(op=TK_EQ; eOp!=(WO_EQ<<(op-TK_EQ)); op++){ assert( op<TK_GE ); }
+  pNew->op = op;
+  idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC);
+  exprAnalyze(pSrc, pWC, idxNew);
+}
+
+#if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY)
+/*
+** Analyze a term that consists of two or more OR-connected
+** subterms.  So in:
+**
+**     ... WHERE  (a=5) AND (b=7 OR c=9 OR d=13) AND (d=13)
+**                          ^^^^^^^^^^^^^^^^^^^^
+**
+** This routine analyzes terms such as the middle term in the above example.
+** A WhereOrTerm object is computed and attached to the term under
+** analysis, regardless of the outcome of the analysis.  Hence:
+**
+**     WhereTerm.wtFlags   |=  TERM_ORINFO
+**     WhereTerm.u.pOrInfo  =  a dynamically allocated WhereOrTerm object
+**
+** The term being analyzed must have two or more of OR-connected subterms.
+** A single subterm might be a set of AND-connected sub-subterms.
+** Examples of terms under analysis:
+**
+**     (A)     t1.x=t2.y OR t1.x=t2.z OR t1.y=15 OR t1.z=t3.a+5
+**     (B)     x=expr1 OR expr2=x OR x=expr3
+**     (C)     t1.x=t2.y OR (t1.x=t2.z AND t1.y=15)
+**     (D)     x=expr1 OR (y>11 AND y<22 AND z LIKE '*hello*')
+**     (E)     (p.a=1 AND q.b=2 AND r.c=3) OR (p.x=4 AND q.y=5 AND r.z=6)
+**     (F)     x>A OR (x=A AND y>=B)
+**
+** CASE 1:
+**
+** If all subterms are of the form T.C=expr for some single column of C and
+** a single table T (as shown in example B above) then create a new virtual
+** term that is an equivalent IN expression.  In other words, if the term
+** being analyzed is:
+**
+**      x = expr1  OR  expr2 = x  OR  x = expr3
+**
+** then create a new virtual term like this:
+**
+**      x IN (expr1,expr2,expr3)
+**
+** CASE 2:
+**
+** If there are exactly two disjuncts and one side has x>A and the other side
+** has x=A (for the same x and A) then add a new virtual conjunct term to the
+** WHERE clause of the form "x>=A".  Example:
+**
+**      x>A OR (x=A AND y>B)    adds:    x>=A
+**
+** The added conjunct can sometimes be helpful in query planning.
+**
+** CASE 3:
+**
+** If all subterms are indexable by a single table T, then set
+**
+**     WhereTerm.eOperator              =  WO_OR
+**     WhereTerm.u.pOrInfo->indexable  |=  the cursor number for table T
+**
+** A subterm is "indexable" if it is of the form
+** "T.C <op> <expr>" where C is any column of table T and 
+** <op> is one of "=", "<", "<=", ">", ">=", "IS NULL", or "IN".
+** A subterm is also indexable if it is an AND of two or more
+** subsubterms at least one of which is indexable.  Indexable AND 
+** subterms have their eOperator set to WO_AND and they have
+** u.pAndInfo set to a dynamically allocated WhereAndTerm object.
+**
+** From another point of view, "indexable" means that the subterm could
+** potentially be used with an index if an appropriate index exists.
+** This analysis does not consider whether or not the index exists; that
+** is decided elsewhere.  This analysis only looks at whether subterms
+** appropriate for indexing exist.
+**
+** All examples A through E above satisfy case 3.  But if a term
+** also satisfies case 1 (such as B) we know that the optimizer will
+** always prefer case 1, so in that case we pretend that case 3 is not
+** satisfied.
+**
+** It might be the case that multiple tables are indexable.  For example,
+** (E) above is indexable on tables P, Q, and R.
+**
+** Terms that satisfy case 3 are candidates for lookup by using
+** separate indices to find rowids for each subterm and composing
+** the union of all rowids using a RowSet object.  This is similar
+** to "bitmap indices" in other database engines.
+**
+** OTHERWISE:
+**
+** If none of cases 1, 2, or 3 apply, then leave the eOperator set to
+** zero.  This term is not useful for search.
+*/
+static void exprAnalyzeOrTerm(
+  SrcList *pSrc,            /* the FROM clause */
+  WhereClause *pWC,         /* the complete WHERE clause */
+  int idxTerm               /* Index of the OR-term to be analyzed */
+){
+  WhereInfo *pWInfo = pWC->pWInfo;        /* WHERE clause processing context */
+  Parse *pParse = pWInfo->pParse;         /* Parser context */
+  sqlite3 *db = pParse->db;               /* Database connection */
+  WhereTerm *pTerm = &pWC->a[idxTerm];    /* The term to be analyzed */
+  Expr *pExpr = pTerm->pExpr;             /* The expression of the term */
+  int i;                                  /* Loop counters */
+  WhereClause *pOrWc;       /* Breakup of pTerm into subterms */
+  WhereTerm *pOrTerm;       /* A Sub-term within the pOrWc */
+  WhereOrInfo *pOrInfo;     /* Additional information associated with pTerm */
+  Bitmask chngToIN;         /* Tables that might satisfy case 1 */
+  Bitmask indexable;        /* Tables that are indexable, satisfying case 2 */
+
+  /*
+  ** Break the OR clause into its separate subterms.  The subterms are
+  ** stored in a WhereClause structure containing within the WhereOrInfo
+  ** object that is attached to the original OR clause term.
+  */
+  assert( (pTerm->wtFlags & (TERM_DYNAMIC|TERM_ORINFO|TERM_ANDINFO))==0 );
+  assert( pExpr->op==TK_OR );
+  pTerm->u.pOrInfo = pOrInfo = sqlite3DbMallocZero(db, sizeof(*pOrInfo));
+  if( pOrInfo==0 ) return;
+  pTerm->wtFlags |= TERM_ORINFO;
+  pOrWc = &pOrInfo->wc;
+  memset(pOrWc->aStatic, 0, sizeof(pOrWc->aStatic));
+  sqlite3WhereClauseInit(pOrWc, pWInfo);
+  sqlite3WhereSplit(pOrWc, pExpr, TK_OR);
+  sqlite3WhereExprAnalyze(pSrc, pOrWc);
+  if( db->mallocFailed ) return;
+  assert( pOrWc->nTerm>=2 );
+
+  /*
+  ** Compute the set of tables that might satisfy cases 1 or 3.
+  */
+  indexable = ~(Bitmask)0;
+  chngToIN = ~(Bitmask)0;
+  for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0 && indexable; i--, pOrTerm++){
+    if( (pOrTerm->eOperator & WO_SINGLE)==0 ){
+      WhereAndInfo *pAndInfo;
+      assert( (pOrTerm->wtFlags & (TERM_ANDINFO|TERM_ORINFO))==0 );
+      chngToIN = 0;
+      pAndInfo = sqlite3DbMallocRawNN(db, sizeof(*pAndInfo));
+      if( pAndInfo ){
+        WhereClause *pAndWC;
+        WhereTerm *pAndTerm;
+        int j;
+        Bitmask b = 0;
+        pOrTerm->u.pAndInfo = pAndInfo;
+        pOrTerm->wtFlags |= TERM_ANDINFO;
+        pOrTerm->eOperator = WO_AND;
+        pAndWC = &pAndInfo->wc;
+        memset(pAndWC->aStatic, 0, sizeof(pAndWC->aStatic));
+        sqlite3WhereClauseInit(pAndWC, pWC->pWInfo);
+        sqlite3WhereSplit(pAndWC, pOrTerm->pExpr, TK_AND);
+        sqlite3WhereExprAnalyze(pSrc, pAndWC);
+        pAndWC->pOuter = pWC;
+        if( !db->mallocFailed ){
+          for(j=0, pAndTerm=pAndWC->a; j<pAndWC->nTerm; j++, pAndTerm++){
+            assert( pAndTerm->pExpr );
+            if( allowedOp(pAndTerm->pExpr->op) 
+             || pAndTerm->eOperator==WO_MATCH 
+            ){
+              b |= sqlite3WhereGetMask(&pWInfo->sMaskSet, pAndTerm->leftCursor);
+            }
+          }
+        }
+        indexable &= b;
+      }
+    }else if( pOrTerm->wtFlags & TERM_COPIED ){
+      /* Skip this term for now.  We revisit it when we process the
+      ** corresponding TERM_VIRTUAL term */
+    }else{
+      Bitmask b;
+      b = sqlite3WhereGetMask(&pWInfo->sMaskSet, pOrTerm->leftCursor);
+      if( pOrTerm->wtFlags & TERM_VIRTUAL ){
+        WhereTerm *pOther = &pOrWc->a[pOrTerm->iParent];
+        b |= sqlite3WhereGetMask(&pWInfo->sMaskSet, pOther->leftCursor);
+      }
+      indexable &= b;
+      if( (pOrTerm->eOperator & WO_EQ)==0 ){
+        chngToIN = 0;
+      }else{
+        chngToIN &= b;
+      }
+    }
+  }
+
+  /*
+  ** Record the set of tables that satisfy case 3.  The set might be
+  ** empty.
+  */
+  pOrInfo->indexable = indexable;
+  pTerm->eOperator = indexable==0 ? 0 : WO_OR;
+
+  /* For a two-way OR, attempt to implementation case 2.
+  */
+  if( indexable && pOrWc->nTerm==2 ){
+    int iOne = 0;
+    WhereTerm *pOne;
+    while( (pOne = whereNthSubterm(&pOrWc->a[0],iOne++))!=0 ){
+      int iTwo = 0;
+      WhereTerm *pTwo;
+      while( (pTwo = whereNthSubterm(&pOrWc->a[1],iTwo++))!=0 ){
+        whereCombineDisjuncts(pSrc, pWC, pOne, pTwo);
+      }
+    }
+  }
+
+  /*
+  ** chngToIN holds a set of tables that *might* satisfy case 1.  But
+  ** we have to do some additional checking to see if case 1 really
+  ** is satisfied.
+  **
+  ** chngToIN will hold either 0, 1, or 2 bits.  The 0-bit case means
+  ** that there is no possibility of transforming the OR clause into an
+  ** IN operator because one or more terms in the OR clause contain
+  ** something other than == on a column in the single table.  The 1-bit
+  ** case means that every term of the OR clause is of the form
+  ** "table.column=expr" for some single table.  The one bit that is set
+  ** will correspond to the common table.  We still need to check to make
+  ** sure the same column is used on all terms.  The 2-bit case is when
+  ** the all terms are of the form "table1.column=table2.column".  It
+  ** might be possible to form an IN operator with either table1.column
+  ** or table2.column as the LHS if either is common to every term of
+  ** the OR clause.
+  **
+  ** Note that terms of the form "table.column1=table.column2" (the
+  ** same table on both sizes of the ==) cannot be optimized.
+  */
+  if( chngToIN ){
+    int okToChngToIN = 0;     /* True if the conversion to IN is valid */
+    int iColumn = -1;         /* Column index on lhs of IN operator */
+    int iCursor = -1;         /* Table cursor common to all terms */
+    int j = 0;                /* Loop counter */
+
+    /* Search for a table and column that appears on one side or the
+    ** other of the == operator in every subterm.  That table and column
+    ** will be recorded in iCursor and iColumn.  There might not be any
+    ** such table and column.  Set okToChngToIN if an appropriate table
+    ** and column is found but leave okToChngToIN false if not found.
+    */
+    for(j=0; j<2 && !okToChngToIN; j++){
+      pOrTerm = pOrWc->a;
+      for(i=pOrWc->nTerm-1; i>=0; i--, pOrTerm++){
+        assert( pOrTerm->eOperator & WO_EQ );
+        pOrTerm->wtFlags &= ~TERM_OR_OK;
+        if( pOrTerm->leftCursor==iCursor ){
+          /* This is the 2-bit case and we are on the second iteration and
+          ** current term is from the first iteration.  So skip this term. */
+          assert( j==1 );
+          continue;
+        }
+        if( (chngToIN & sqlite3WhereGetMask(&pWInfo->sMaskSet,
+                                            pOrTerm->leftCursor))==0 ){
+          /* This term must be of the form t1.a==t2.b where t2 is in the
+          ** chngToIN set but t1 is not.  This term will be either preceded
+          ** or follwed by an inverted copy (t2.b==t1.a).  Skip this term 
+          ** and use its inversion. */
+          testcase( pOrTerm->wtFlags & TERM_COPIED );
+          testcase( pOrTerm->wtFlags & TERM_VIRTUAL );
+          assert( pOrTerm->wtFlags & (TERM_COPIED|TERM_VIRTUAL) );
+          continue;
+        }
+        iColumn = pOrTerm->u.leftColumn;
+        iCursor = pOrTerm->leftCursor;
+        break;
+      }
+      if( i<0 ){
+        /* No candidate table+column was found.  This can only occur
+        ** on the second iteration */
+        assert( j==1 );
+        assert( IsPowerOfTwo(chngToIN) );
+        assert( chngToIN==sqlite3WhereGetMask(&pWInfo->sMaskSet, iCursor) );
+        break;
+      }
+      testcase( j==1 );
+
+      /* We have found a candidate table and column.  Check to see if that
+      ** table and column is common to every term in the OR clause */
+      okToChngToIN = 1;
+      for(; i>=0 && okToChngToIN; i--, pOrTerm++){
+        assert( pOrTerm->eOperator & WO_EQ );
+        if( pOrTerm->leftCursor!=iCursor ){
+          pOrTerm->wtFlags &= ~TERM_OR_OK;
+        }else if( pOrTerm->u.leftColumn!=iColumn ){
+          okToChngToIN = 0;
+        }else{
+          int affLeft, affRight;
+          /* If the right-hand side is also a column, then the affinities
+          ** of both right and left sides must be such that no type
+          ** conversions are required on the right.  (Ticket #2249)
+          */
+          affRight = sqlite3ExprAffinity(pOrTerm->pExpr->pRight);
+          affLeft = sqlite3ExprAffinity(pOrTerm->pExpr->pLeft);
+          if( affRight!=0 && affRight!=affLeft ){
+            okToChngToIN = 0;
+          }else{
+            pOrTerm->wtFlags |= TERM_OR_OK;
+          }
+        }
+      }
+    }
+
+    /* At this point, okToChngToIN is true if original pTerm satisfies
+    ** case 1.  In that case, construct a new virtual term that is 
+    ** pTerm converted into an IN operator.
+    */
+    if( okToChngToIN ){
+      Expr *pDup;            /* A transient duplicate expression */
+      ExprList *pList = 0;   /* The RHS of the IN operator */
+      Expr *pLeft = 0;       /* The LHS of the IN operator */
+      Expr *pNew;            /* The complete IN operator */
+
+      for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0; i--, pOrTerm++){
+        if( (pOrTerm->wtFlags & TERM_OR_OK)==0 ) continue;
+        assert( pOrTerm->eOperator & WO_EQ );
+        assert( pOrTerm->leftCursor==iCursor );
+        assert( pOrTerm->u.leftColumn==iColumn );
+        pDup = sqlite3ExprDup(db, pOrTerm->pExpr->pRight, 0);
+        pList = sqlite3ExprListAppend(pWInfo->pParse, pList, pDup);
+        pLeft = pOrTerm->pExpr->pLeft;
+      }
+      assert( pLeft!=0 );
+      pDup = sqlite3ExprDup(db, pLeft, 0);
+      pNew = sqlite3PExpr(pParse, TK_IN, pDup, 0, 0);
+      if( pNew ){
+        int idxNew;
+        transferJoinMarkings(pNew, pExpr);
+        assert( !ExprHasProperty(pNew, EP_xIsSelect) );
+        pNew->x.pList = pList;
+        idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC);
+        testcase( idxNew==0 );
+        exprAnalyze(pSrc, pWC, idxNew);
+        pTerm = &pWC->a[idxTerm];
+        markTermAsChild(pWC, idxNew, idxTerm);
+      }else{
+        sqlite3ExprListDelete(db, pList);
+      }
+      pTerm->eOperator = WO_NOOP;  /* case 1 trumps case 3 */
+    }
+  }
+}
+#endif /* !SQLITE_OMIT_OR_OPTIMIZATION && !SQLITE_OMIT_SUBQUERY */
+
+/*
+** We already know that pExpr is a binary operator where both operands are
+** column references.  This routine checks to see if pExpr is an equivalence
+** relation:
+**   1.  The SQLITE_Transitive optimization must be enabled
+**   2.  Must be either an == or an IS operator
+**   3.  Not originating in the ON clause of an OUTER JOIN
+**   4.  The affinities of A and B must be compatible
+**   5a. Both operands use the same collating sequence OR
+**   5b. The overall collating sequence is BINARY
+** If this routine returns TRUE, that means that the RHS can be substituted
+** for the LHS anyplace else in the WHERE clause where the LHS column occurs.
+** This is an optimization.  No harm comes from returning 0.  But if 1 is
+** returned when it should not be, then incorrect answers might result.
+*/
+static int termIsEquivalence(Parse *pParse, Expr *pExpr){
+  char aff1, aff2;
+  CollSeq *pColl;
+  const char *zColl1, *zColl2;
+  if( !OptimizationEnabled(pParse->db, SQLITE_Transitive) ) return 0;
+  if( pExpr->op!=TK_EQ && pExpr->op!=TK_IS ) return 0;
+  if( ExprHasProperty(pExpr, EP_FromJoin) ) return 0;
+  aff1 = sqlite3ExprAffinity(pExpr->pLeft);
+  aff2 = sqlite3ExprAffinity(pExpr->pRight);
+  if( aff1!=aff2
+   && (!sqlite3IsNumericAffinity(aff1) || !sqlite3IsNumericAffinity(aff2))
+  ){
+    return 0;
+  }
+  pColl = sqlite3BinaryCompareCollSeq(pParse, pExpr->pLeft, pExpr->pRight);
+  if( pColl==0 || sqlite3StrICmp(pColl->zName, "BINARY")==0 ) return 1;
+  pColl = sqlite3ExprCollSeq(pParse, pExpr->pLeft);
+  zColl1 = pColl ? pColl->zName : 0;
+  pColl = sqlite3ExprCollSeq(pParse, pExpr->pRight);
+  zColl2 = pColl ? pColl->zName : 0;
+  return sqlite3_stricmp(zColl1, zColl2)==0;
+}
+
+/*
+** Recursively walk the expressions of a SELECT statement and generate
+** a bitmask indicating which tables are used in that expression
+** tree.
+*/
+static Bitmask exprSelectUsage(WhereMaskSet *pMaskSet, Select *pS){
+  Bitmask mask = 0;
+  while( pS ){
+    SrcList *pSrc = pS->pSrc;
+    mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pEList);
+    mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pGroupBy);
+    mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pOrderBy);
+    mask |= sqlite3WhereExprUsage(pMaskSet, pS->pWhere);
+    mask |= sqlite3WhereExprUsage(pMaskSet, pS->pHaving);
+    if( ALWAYS(pSrc!=0) ){
+      int i;
+      for(i=0; i<pSrc->nSrc; i++){
+        mask |= exprSelectUsage(pMaskSet, pSrc->a[i].pSelect);
+        mask |= sqlite3WhereExprUsage(pMaskSet, pSrc->a[i].pOn);
+      }
+    }
+    pS = pS->pPrior;
+  }
+  return mask;
+}
+
+/*
+** Expression pExpr is one operand of a comparison operator that might
+** be useful for indexing.  This routine checks to see if pExpr appears
+** in any index.  Return TRUE (1) if pExpr is an indexed term and return
+** FALSE (0) if not.  If TRUE is returned, also set *piCur to the cursor
+** number of the table that is indexed and *piColumn to the column number
+** of the column that is indexed, or XN_EXPR (-2) if an expression is being
+** indexed.
+**
+** If pExpr is a TK_COLUMN column reference, then this routine always returns
+** true even if that particular column is not indexed, because the column
+** might be added to an automatic index later.
+*/
+static int exprMightBeIndexed(
+  SrcList *pFrom,        /* The FROM clause */
+  int op,                /* The specific comparison operator */
+  Bitmask mPrereq,       /* Bitmask of FROM clause terms referenced by pExpr */
+  Expr *pExpr,           /* An operand of a comparison operator */
+  int *piCur,            /* Write the referenced table cursor number here */
+  int *piColumn          /* Write the referenced table column number here */
+){
+  Index *pIdx;
+  int i;
+  int iCur;
+
+  /* If this expression is a vector to the left or right of a 
+  ** inequality constraint (>, <, >= or <=), perform the processing 
+  ** on the first element of the vector.  */
+  assert( TK_GT+1==TK_LE && TK_GT+2==TK_LT && TK_GT+3==TK_GE );
+  assert( TK_IS<TK_GE && TK_ISNULL<TK_GE && TK_IN<TK_GE );
+  assert( op<=TK_GE );
+  if( pExpr->op==TK_VECTOR && (op>=TK_GT && ALWAYS(op<=TK_GE)) ){
+    pExpr = pExpr->x.pList->a[0].pExpr;
+  }
+
+  if( pExpr->op==TK_COLUMN ){
+    *piCur = pExpr->iTable;
+    *piColumn = pExpr->iColumn;
+    return 1;
+  }
+  if( mPrereq==0 ) return 0;                 /* No table references */
+  if( (mPrereq&(mPrereq-1))!=0 ) return 0;   /* Refs more than one table */
+  for(i=0; mPrereq>1; i++, mPrereq>>=1){}
+  iCur = pFrom->a[i].iCursor;
+  for(pIdx=pFrom->a[i].pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+    if( pIdx->aColExpr==0 ) continue;
+    for(i=0; i<pIdx->nKeyCol; i++){
+      if( pIdx->aiColumn[i]!=XN_EXPR ) continue;
+      if( sqlite3ExprCompare(pExpr, pIdx->aColExpr->a[i].pExpr, iCur)==0 ){
+        *piCur = iCur;
+        *piColumn = XN_EXPR;
+        return 1;
+      }
+    }
+  }
+  return 0;
+}
+
+/*
+** The input to this routine is an WhereTerm structure with only the
+** "pExpr" field filled in.  The job of this routine is to analyze the
+** subexpression and populate all the other fields of the WhereTerm
+** structure.
+**
+** If the expression is of the form "<expr> <op> X" it gets commuted
+** to the standard form of "X <op> <expr>".
+**
+** If the expression is of the form "X <op> Y" where both X and Y are
+** columns, then the original expression is unchanged and a new virtual
+** term of the form "Y <op> X" is added to the WHERE clause and
+** analyzed separately.  The original term is marked with TERM_COPIED
+** and the new term is marked with TERM_DYNAMIC (because it's pExpr
+** needs to be freed with the WhereClause) and TERM_VIRTUAL (because it
+** is a commuted copy of a prior term.)  The original term has nChild=1
+** and the copy has idxParent set to the index of the original term.
+*/
+static void exprAnalyze(
+  SrcList *pSrc,            /* the FROM clause */
+  WhereClause *pWC,         /* the WHERE clause */
+  int idxTerm               /* Index of the term to be analyzed */
+){
+  WhereInfo *pWInfo = pWC->pWInfo; /* WHERE clause processing context */
+  WhereTerm *pTerm;                /* The term to be analyzed */
+  WhereMaskSet *pMaskSet;          /* Set of table index masks */
+  Expr *pExpr;                     /* The expression to be analyzed */
+  Bitmask prereqLeft;              /* Prerequesites of the pExpr->pLeft */
+  Bitmask prereqAll;               /* Prerequesites of pExpr */
+  Bitmask extraRight = 0;          /* Extra dependencies on LEFT JOIN */
+  Expr *pStr1 = 0;                 /* RHS of LIKE/GLOB operator */
+  int isComplete = 0;              /* RHS of LIKE/GLOB ends with wildcard */
+  int noCase = 0;                  /* uppercase equivalent to lowercase */
+  int op;                          /* Top-level operator.  pExpr->op */
+  Parse *pParse = pWInfo->pParse;  /* Parsing context */
+  sqlite3 *db = pParse->db;        /* Database connection */
+  unsigned char eOp2;              /* op2 value for LIKE/REGEXP/GLOB */
+
+  if( db->mallocFailed ){
+    return;
+  }
+  pTerm = &pWC->a[idxTerm];
+  pMaskSet = &pWInfo->sMaskSet;
+  pExpr = pTerm->pExpr;
+  assert( pExpr->op!=TK_AS && pExpr->op!=TK_COLLATE );
+  prereqLeft = sqlite3WhereExprUsage(pMaskSet, pExpr->pLeft);
+  op = pExpr->op;
+  if( op==TK_IN ){
+    assert( pExpr->pRight==0 );
+    if( sqlite3ExprCheckIN(pParse, pExpr) ) return;
+    if( ExprHasProperty(pExpr, EP_xIsSelect) ){
+      pTerm->prereqRight = exprSelectUsage(pMaskSet, pExpr->x.pSelect);
+    }else{
+      pTerm->prereqRight = sqlite3WhereExprListUsage(pMaskSet, pExpr->x.pList);
+    }
+  }else if( op==TK_ISNULL ){
+    pTerm->prereqRight = 0;
+  }else{
+    pTerm->prereqRight = sqlite3WhereExprUsage(pMaskSet, pExpr->pRight);
+  }
+  prereqAll = sqlite3WhereExprUsage(pMaskSet, pExpr);
+  if( ExprHasProperty(pExpr, EP_FromJoin) ){
+    Bitmask x = sqlite3WhereGetMask(pMaskSet, pExpr->iRightJoinTable);
+    prereqAll |= x;
+    extraRight = x-1;  /* ON clause terms may not be used with an index
+                       ** on left table of a LEFT JOIN.  Ticket #3015 */
+  }
+  pTerm->prereqAll = prereqAll;
+  pTerm->leftCursor = -1;
+  pTerm->iParent = -1;
+  pTerm->eOperator = 0;
+  if( allowedOp(op) ){
+    int iCur, iColumn;
+    Expr *pLeft = sqlite3ExprSkipCollate(pExpr->pLeft);
+    Expr *pRight = sqlite3ExprSkipCollate(pExpr->pRight);
+    u16 opMask = (pTerm->prereqRight & prereqLeft)==0 ? WO_ALL : WO_EQUIV;
+
+    if( pTerm->iField>0 ){
+      assert( op==TK_IN );
+      assert( pLeft->op==TK_VECTOR );
+      pLeft = pLeft->x.pList->a[pTerm->iField-1].pExpr;
+    }
+
+    if( exprMightBeIndexed(pSrc, op, prereqLeft, pLeft, &iCur, &iColumn) ){
+      pTerm->leftCursor = iCur;
+      pTerm->u.leftColumn = iColumn;
+      pTerm->eOperator = operatorMask(op) & opMask;
+    }
+    if( op==TK_IS ) pTerm->wtFlags |= TERM_IS;
+    if( pRight 
+     && exprMightBeIndexed(pSrc, op, pTerm->prereqRight, pRight, &iCur,&iColumn)
+    ){
+      WhereTerm *pNew;
+      Expr *pDup;
+      u16 eExtraOp = 0;        /* Extra bits for pNew->eOperator */
+      assert( pTerm->iField==0 );
+      if( pTerm->leftCursor>=0 ){
+        int idxNew;
+        pDup = sqlite3ExprDup(db, pExpr, 0);
+        if( db->mallocFailed ){
+          sqlite3ExprDelete(db, pDup);
+          return;
+        }
+        idxNew = whereClauseInsert(pWC, pDup, TERM_VIRTUAL|TERM_DYNAMIC);
+        if( idxNew==0 ) return;
+        pNew = &pWC->a[idxNew];
+        markTermAsChild(pWC, idxNew, idxTerm);
+        if( op==TK_IS ) pNew->wtFlags |= TERM_IS;
+        pTerm = &pWC->a[idxTerm];
+        pTerm->wtFlags |= TERM_COPIED;
+
+        if( termIsEquivalence(pParse, pDup) ){
+          pTerm->eOperator |= WO_EQUIV;
+          eExtraOp = WO_EQUIV;
+        }
+      }else{
+        pDup = pExpr;
+        pNew = pTerm;
+      }
+      exprCommute(pParse, pDup);
+      pNew->leftCursor = iCur;
+      pNew->u.leftColumn = iColumn;
+      testcase( (prereqLeft | extraRight) != prereqLeft );
+      pNew->prereqRight = prereqLeft | extraRight;
+      pNew->prereqAll = prereqAll;
+      pNew->eOperator = (operatorMask(pDup->op) + eExtraOp) & opMask;
+    }
+  }
+
+#ifndef SQLITE_OMIT_BETWEEN_OPTIMIZATION
+  /* If a term is the BETWEEN operator, create two new virtual terms
+  ** that define the range that the BETWEEN implements.  For example:
+  **
+  **      a BETWEEN b AND c
+  **
+  ** is converted into:
+  **
+  **      (a BETWEEN b AND c) AND (a>=b) AND (a<=c)
+  **
+  ** The two new terms are added onto the end of the WhereClause object.
+  ** The new terms are "dynamic" and are children of the original BETWEEN
+  ** term.  That means that if the BETWEEN term is coded, the children are
+  ** skipped.  Or, if the children are satisfied by an index, the original
+  ** BETWEEN term is skipped.
+  */
+  else if( pExpr->op==TK_BETWEEN && pWC->op==TK_AND ){
+    ExprList *pList = pExpr->x.pList;
+    int i;
+    static const u8 ops[] = {TK_GE, TK_LE};
+    assert( pList!=0 );
+    assert( pList->nExpr==2 );
+    for(i=0; i<2; i++){
+      Expr *pNewExpr;
+      int idxNew;
+      pNewExpr = sqlite3PExpr(pParse, ops[i], 
+                             sqlite3ExprDup(db, pExpr->pLeft, 0),
+                             sqlite3ExprDup(db, pList->a[i].pExpr, 0), 0);
+      transferJoinMarkings(pNewExpr, pExpr);
+      idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
+      testcase( idxNew==0 );
+      exprAnalyze(pSrc, pWC, idxNew);
+      pTerm = &pWC->a[idxTerm];
+      markTermAsChild(pWC, idxNew, idxTerm);
+    }
+  }
+#endif /* SQLITE_OMIT_BETWEEN_OPTIMIZATION */
+
+#if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY)
+  /* Analyze a term that is composed of two or more subterms connected by
+  ** an OR operator.
+  */
+  else if( pExpr->op==TK_OR ){
+    assert( pWC->op==TK_AND );
+    exprAnalyzeOrTerm(pSrc, pWC, idxTerm);
+    pTerm = &pWC->a[idxTerm];
+  }
+#endif /* SQLITE_OMIT_OR_OPTIMIZATION */
+
+#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
+  /* Add constraints to reduce the search space on a LIKE or GLOB
+  ** operator.
+  **
+  ** A like pattern of the form "x LIKE 'aBc%'" is changed into constraints
+  **
+  **          x>='ABC' AND x<'abd' AND x LIKE 'aBc%'
+  **
+  ** The last character of the prefix "abc" is incremented to form the
+  ** termination condition "abd".  If case is not significant (the default
+  ** for LIKE) then the lower-bound is made all uppercase and the upper-
+  ** bound is made all lowercase so that the bounds also work when comparing
+  ** BLOBs.
+  */
+  if( pWC->op==TK_AND 
+   && isLikeOrGlob(pParse, pExpr, &pStr1, &isComplete, &noCase)
+  ){
+    Expr *pLeft;       /* LHS of LIKE/GLOB operator */
+    Expr *pStr2;       /* Copy of pStr1 - RHS of LIKE/GLOB operator */
+    Expr *pNewExpr1;
+    Expr *pNewExpr2;
+    int idxNew1;
+    int idxNew2;
+    const char *zCollSeqName;     /* Name of collating sequence */
+    const u16 wtFlags = TERM_LIKEOPT | TERM_VIRTUAL | TERM_DYNAMIC;
+
+    pLeft = pExpr->x.pList->a[1].pExpr;
+    pStr2 = sqlite3ExprDup(db, pStr1, 0);
+
+    /* Convert the lower bound to upper-case and the upper bound to
+    ** lower-case (upper-case is less than lower-case in ASCII) so that
+    ** the range constraints also work for BLOBs
+    */
+    if( noCase && !pParse->db->mallocFailed ){
+      int i;
+      char c;
+      pTerm->wtFlags |= TERM_LIKE;
+      for(i=0; (c = pStr1->u.zToken[i])!=0; i++){
+        pStr1->u.zToken[i] = sqlite3Toupper(c);
+        pStr2->u.zToken[i] = sqlite3Tolower(c);
+      }
+    }
+
+    if( !db->mallocFailed ){
+      u8 c, *pC;       /* Last character before the first wildcard */
+      pC = (u8*)&pStr2->u.zToken[sqlite3Strlen30(pStr2->u.zToken)-1];
+      c = *pC;
+      if( noCase ){
+        /* The point is to increment the last character before the first
+        ** wildcard.  But if we increment '@', that will push it into the
+        ** alphabetic range where case conversions will mess up the 
+        ** inequality.  To avoid this, make sure to also run the full
+        ** LIKE on all candidate expressions by clearing the isComplete flag
+        */
+        if( c=='A'-1 ) isComplete = 0;
+        c = sqlite3UpperToLower[c];
+      }
+      *pC = c + 1;
+    }
+    zCollSeqName = noCase ? "NOCASE" : "BINARY";
+    pNewExpr1 = sqlite3ExprDup(db, pLeft, 0);
+    pNewExpr1 = sqlite3PExpr(pParse, TK_GE,
+           sqlite3ExprAddCollateString(pParse,pNewExpr1,zCollSeqName),
+           pStr1, 0);
+    transferJoinMarkings(pNewExpr1, pExpr);
+    idxNew1 = whereClauseInsert(pWC, pNewExpr1, wtFlags);
+    testcase( idxNew1==0 );
+    exprAnalyze(pSrc, pWC, idxNew1);
+    pNewExpr2 = sqlite3ExprDup(db, pLeft, 0);
+    pNewExpr2 = sqlite3PExpr(pParse, TK_LT,
+           sqlite3ExprAddCollateString(pParse,pNewExpr2,zCollSeqName),
+           pStr2, 0);
+    transferJoinMarkings(pNewExpr2, pExpr);
+    idxNew2 = whereClauseInsert(pWC, pNewExpr2, wtFlags);
+    testcase( idxNew2==0 );
+    exprAnalyze(pSrc, pWC, idxNew2);
+    pTerm = &pWC->a[idxTerm];
+    if( isComplete ){
+      markTermAsChild(pWC, idxNew1, idxTerm);
+      markTermAsChild(pWC, idxNew2, idxTerm);
+    }
+  }
+#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  /* Add a WO_MATCH auxiliary term to the constraint set if the
+  ** current expression is of the form:  column MATCH expr.
+  ** This information is used by the xBestIndex methods of
+  ** virtual tables.  The native query optimizer does not attempt
+  ** to do anything with MATCH functions.
+  */
+  if( pWC->op==TK_AND && isMatchOfColumn(pExpr, &eOp2) ){
+    int idxNew;
+    Expr *pRight, *pLeft;
+    WhereTerm *pNewTerm;
+    Bitmask prereqColumn, prereqExpr;
+
+    pRight = pExpr->x.pList->a[0].pExpr;
+    pLeft = pExpr->x.pList->a[1].pExpr;
+    prereqExpr = sqlite3WhereExprUsage(pMaskSet, pRight);
+    prereqColumn = sqlite3WhereExprUsage(pMaskSet, pLeft);
+    if( (prereqExpr & prereqColumn)==0 ){
+      Expr *pNewExpr;
+      pNewExpr = sqlite3PExpr(pParse, TK_MATCH, 
+                              0, sqlite3ExprDup(db, pRight, 0), 0);
+      idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
+      testcase( idxNew==0 );
+      pNewTerm = &pWC->a[idxNew];
+      pNewTerm->prereqRight = prereqExpr;
+      pNewTerm->leftCursor = pLeft->iTable;
+      pNewTerm->u.leftColumn = pLeft->iColumn;
+      pNewTerm->eOperator = WO_MATCH;
+      pNewTerm->eMatchOp = eOp2;
+      markTermAsChild(pWC, idxNew, idxTerm);
+      pTerm = &pWC->a[idxTerm];
+      pTerm->wtFlags |= TERM_COPIED;
+      pNewTerm->prereqAll = pTerm->prereqAll;
+    }
+  }
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+  /* If there is a vector == or IS term - e.g. "(a, b) == (?, ?)" - create
+  ** new terms for each component comparison - "a = ?" and "b = ?".  The
+  ** new terms completely replace the original vector comparison, which is
+  ** no longer used.
+  **
+  ** This is only required if at least one side of the comparison operation
+  ** is not a sub-select.  */
+  if( pWC->op==TK_AND 
+  && (pExpr->op==TK_EQ || pExpr->op==TK_IS)
+  && sqlite3ExprIsVector(pExpr->pLeft)
+  && ( (pExpr->pLeft->flags & EP_xIsSelect)==0 
+    || (pExpr->pRight->flags & EP_xIsSelect)==0
+  )){
+    int nLeft = sqlite3ExprVectorSize(pExpr->pLeft);
+    int i;
+    assert( nLeft==sqlite3ExprVectorSize(pExpr->pRight) );
+    for(i=0; i<nLeft; i++){
+      int idxNew;
+      Expr *pNew;
+      Expr *pLeft = sqlite3ExprForVectorField(pParse, pExpr->pLeft, i);
+      Expr *pRight = sqlite3ExprForVectorField(pParse, pExpr->pRight, i);
+
+      pNew = sqlite3PExpr(pParse, pExpr->op, pLeft, pRight, 0);
+      transferJoinMarkings(pNew, pExpr);
+      idxNew = whereClauseInsert(pWC, pNew, TERM_DYNAMIC);
+      exprAnalyze(pSrc, pWC, idxNew);
+    }
+    pTerm = &pWC->a[idxTerm];
+    pTerm->wtFlags = TERM_CODED|TERM_VIRTUAL;  /* Disable the original */
+    pTerm->eOperator = 0;
+  }
+
+  /* If there is a vector IN term - e.g. "(a, b) IN (SELECT ...)" - create
+  ** a virtual term for each vector component. The expression object
+  ** used by each such virtual term is pExpr (the full vector IN(...) 
+  ** expression). The WhereTerm.iField variable identifies the index within
+  ** the vector on the LHS that the virtual term represents.
+  **
+  ** This only works if the RHS is a simple SELECT, not a compound
+  */
+  if( pWC->op==TK_AND && pExpr->op==TK_IN && pTerm->iField==0
+   && pExpr->pLeft->op==TK_VECTOR
+   && pExpr->x.pSelect->pPrior==0
+  ){
+    int i;
+    for(i=0; i<sqlite3ExprVectorSize(pExpr->pLeft); i++){
+      int idxNew;
+      idxNew = whereClauseInsert(pWC, pExpr, TERM_VIRTUAL);
+      pWC->a[idxNew].iField = i+1;
+      exprAnalyze(pSrc, pWC, idxNew);
+      markTermAsChild(pWC, idxNew, idxTerm);
+    }
+  }
+
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  /* When sqlite_stat3 histogram data is available an operator of the
+  ** form "x IS NOT NULL" can sometimes be evaluated more efficiently
+  ** as "x>NULL" if x is not an INTEGER PRIMARY KEY.  So construct a
+  ** virtual term of that form.
+  **
+  ** Note that the virtual term must be tagged with TERM_VNULL.
+  */
+  if( pExpr->op==TK_NOTNULL
+   && pExpr->pLeft->op==TK_COLUMN
+   && pExpr->pLeft->iColumn>=0
+   && OptimizationEnabled(db, SQLITE_Stat34)
+  ){
+    Expr *pNewExpr;
+    Expr *pLeft = pExpr->pLeft;
+    int idxNew;
+    WhereTerm *pNewTerm;
+
+    pNewExpr = sqlite3PExpr(pParse, TK_GT,
+                            sqlite3ExprDup(db, pLeft, 0),
+                            sqlite3ExprAlloc(db, TK_NULL, 0, 0), 0);
+
+    idxNew = whereClauseInsert(pWC, pNewExpr,
+                              TERM_VIRTUAL|TERM_DYNAMIC|TERM_VNULL);
+    if( idxNew ){
+      pNewTerm = &pWC->a[idxNew];
+      pNewTerm->prereqRight = 0;
+      pNewTerm->leftCursor = pLeft->iTable;
+      pNewTerm->u.leftColumn = pLeft->iColumn;
+      pNewTerm->eOperator = WO_GT;
+      markTermAsChild(pWC, idxNew, idxTerm);
+      pTerm = &pWC->a[idxTerm];
+      pTerm->wtFlags |= TERM_COPIED;
+      pNewTerm->prereqAll = pTerm->prereqAll;
+    }
+  }
+#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
+
+  /* Prevent ON clause terms of a LEFT JOIN from being used to drive
+  ** an index for tables to the left of the join.
+  */
+  testcase( pTerm!=&pWC->a[idxTerm] );
+  pTerm = &pWC->a[idxTerm];
+  pTerm->prereqRight |= extraRight;
+}
+
+/***************************************************************************
+** Routines with file scope above.  Interface to the rest of the where.c
+** subsystem follows.
+***************************************************************************/
+
+/*
+** This routine identifies subexpressions in the WHERE clause where
+** each subexpression is separated by the AND operator or some other
+** operator specified in the op parameter.  The WhereClause structure
+** is filled with pointers to subexpressions.  For example:
+**
+**    WHERE  a=='hello' AND coalesce(b,11)<10 AND (c+12!=d OR c==22)
+**           \________/     \_______________/     \________________/
+**            slot[0]            slot[1]               slot[2]
+**
+** The original WHERE clause in pExpr is unaltered.  All this routine
+** does is make slot[] entries point to substructure within pExpr.
+**
+** In the previous sentence and in the diagram, "slot[]" refers to
+** the WhereClause.a[] array.  The slot[] array grows as needed to contain
+** all terms of the WHERE clause.
+*/
+SQLITE_PRIVATE void sqlite3WhereSplit(WhereClause *pWC, Expr *pExpr, u8 op){
+  Expr *pE2 = sqlite3ExprSkipCollate(pExpr);
+  pWC->op = op;
+  if( pE2==0 ) return;
+  if( pE2->op!=op ){
+    whereClauseInsert(pWC, pExpr, 0);
+  }else{
+    sqlite3WhereSplit(pWC, pE2->pLeft, op);
+    sqlite3WhereSplit(pWC, pE2->pRight, op);
+  }
+}
+
+/*
+** Initialize a preallocated WhereClause structure.
+*/
+SQLITE_PRIVATE void sqlite3WhereClauseInit(
+  WhereClause *pWC,        /* The WhereClause to be initialized */
+  WhereInfo *pWInfo        /* The WHERE processing context */
+){
+  pWC->pWInfo = pWInfo;
+  pWC->pOuter = 0;
+  pWC->nTerm = 0;
+  pWC->nSlot = ArraySize(pWC->aStatic);
+  pWC->a = pWC->aStatic;
+}
+
+/*
+** Deallocate a WhereClause structure.  The WhereClause structure
+** itself is not freed.  This routine is the inverse of
+** sqlite3WhereClauseInit().
+*/
+SQLITE_PRIVATE void sqlite3WhereClauseClear(WhereClause *pWC){
+  int i;
+  WhereTerm *a;
+  sqlite3 *db = pWC->pWInfo->pParse->db;
+  for(i=pWC->nTerm-1, a=pWC->a; i>=0; i--, a++){
+    if( a->wtFlags & TERM_DYNAMIC ){
+      sqlite3ExprDelete(db, a->pExpr);
+    }
+    if( a->wtFlags & TERM_ORINFO ){
+      whereOrInfoDelete(db, a->u.pOrInfo);
+    }else if( a->wtFlags & TERM_ANDINFO ){
+      whereAndInfoDelete(db, a->u.pAndInfo);
+    }
+  }
+  if( pWC->a!=pWC->aStatic ){
+    sqlite3DbFree(db, pWC->a);
+  }
+}
+
+
+/*
+** These routines walk (recursively) an expression tree and generate
+** a bitmask indicating which tables are used in that expression
+** tree.
+*/
+SQLITE_PRIVATE Bitmask sqlite3WhereExprUsage(WhereMaskSet *pMaskSet, Expr *p){
+  Bitmask mask;
+  if( p==0 ) return 0;
+  if( p->op==TK_COLUMN ){
+    mask = sqlite3WhereGetMask(pMaskSet, p->iTable);
+    return mask;
+  }
+  assert( !ExprHasProperty(p, EP_TokenOnly) );
+  mask = p->pRight ? sqlite3WhereExprUsage(pMaskSet, p->pRight) : 0;
+  if( p->pLeft ) mask |= sqlite3WhereExprUsage(pMaskSet, p->pLeft);
+  if( ExprHasProperty(p, EP_xIsSelect) ){
+    mask |= exprSelectUsage(pMaskSet, p->x.pSelect);
+  }else if( p->x.pList ){
+    mask |= sqlite3WhereExprListUsage(pMaskSet, p->x.pList);
+  }
+  return mask;
+}
+SQLITE_PRIVATE Bitmask sqlite3WhereExprListUsage(WhereMaskSet *pMaskSet, ExprList *pList){
+  int i;
+  Bitmask mask = 0;
+  if( pList ){
+    for(i=0; i<pList->nExpr; i++){
+      mask |= sqlite3WhereExprUsage(pMaskSet, pList->a[i].pExpr);
+    }
+  }
+  return mask;
+}
+
+
+/*
+** Call exprAnalyze on all terms in a WHERE clause.  
+**
+** Note that exprAnalyze() might add new virtual terms onto the
+** end of the WHERE clause.  We do not want to analyze these new
+** virtual terms, so start analyzing at the end and work forward
+** so that the added virtual terms are never processed.
+*/
+SQLITE_PRIVATE void sqlite3WhereExprAnalyze(
+  SrcList *pTabList,       /* the FROM clause */
+  WhereClause *pWC         /* the WHERE clause to be analyzed */
+){
+  int i;
+  for(i=pWC->nTerm-1; i>=0; i--){
+    exprAnalyze(pTabList, pWC, i);
+  }
+}
+
+/*
+** For table-valued-functions, transform the function arguments into
+** new WHERE clause terms.  
+**
+** Each function argument translates into an equality constraint against
+** a HIDDEN column in the table.
+*/
+SQLITE_PRIVATE void sqlite3WhereTabFuncArgs(
+  Parse *pParse,                    /* Parsing context */
+  struct SrcList_item *pItem,       /* The FROM clause term to process */
+  WhereClause *pWC                  /* Xfer function arguments to here */
+){
+  Table *pTab;
+  int j, k;
+  ExprList *pArgs;
+  Expr *pColRef;
+  Expr *pTerm;
+  if( pItem->fg.isTabFunc==0 ) return;
+  pTab = pItem->pTab;
+  assert( pTab!=0 );
+  pArgs = pItem->u1.pFuncArg;
+  if( pArgs==0 ) return;
+  for(j=k=0; j<pArgs->nExpr; j++){
+    while( k<pTab->nCol && (pTab->aCol[k].colFlags & COLFLAG_HIDDEN)==0 ){k++;}
+    if( k>=pTab->nCol ){
+      sqlite3ErrorMsg(pParse, "too many arguments on %s() - max %d",
+                      pTab->zName, j);
+      return;
+    }
+    pColRef = sqlite3ExprAlloc(pParse->db, TK_COLUMN, 0, 0);
+    if( pColRef==0 ) return;
+    pColRef->iTable = pItem->iCursor;
+    pColRef->iColumn = k++;
+    pColRef->pTab = pTab;
+    pTerm = sqlite3PExpr(pParse, TK_EQ, pColRef,
+                         sqlite3ExprDup(pParse->db, pArgs->a[j].pExpr, 0), 0);
+    whereClauseInsert(pWC, pTerm, TERM_DYNAMIC);
+  }
+}
+
+/************** End of whereexpr.c *******************************************/
+/************** Begin file where.c *******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This module contains C code that generates VDBE code used to process
+** the WHERE clause of SQL statements.  This module is responsible for
+** generating the code that loops through a table looking for applicable
+** rows.  Indices are selected and used to speed the search when doing
+** so is applicable.  Because this module is responsible for selecting
+** indices, you might also think of this module as the "query optimizer".
+*/
+/* #include "sqliteInt.h" */
+/* #include "whereInt.h" */
+
+/* Forward declaration of methods */
+static int whereLoopResize(sqlite3*, WhereLoop*, int);
+
+/* Test variable that can be set to enable WHERE tracing */
+#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
+/***/ int sqlite3WhereTrace = 0;
+#endif
+
+
+/*
+** Return the estimated number of output rows from a WHERE clause
+*/
+SQLITE_PRIVATE LogEst sqlite3WhereOutputRowCount(WhereInfo *pWInfo){
+  return pWInfo->nRowOut;
+}
+
+/*
+** Return one of the WHERE_DISTINCT_xxxxx values to indicate how this
+** WHERE clause returns outputs for DISTINCT processing.
+*/
+SQLITE_PRIVATE int sqlite3WhereIsDistinct(WhereInfo *pWInfo){
+  return pWInfo->eDistinct;
+}
+
+/*
+** Return TRUE if the WHERE clause returns rows in ORDER BY order.
+** Return FALSE if the output needs to be sorted.
+*/
+SQLITE_PRIVATE int sqlite3WhereIsOrdered(WhereInfo *pWInfo){
+  return pWInfo->nOBSat;
+}
+
+/*
+** Return TRUE if the innermost loop of the WHERE clause implementation
+** returns rows in ORDER BY order for complete run of the inner loop.
+**
+** Across multiple iterations of outer loops, the output rows need not be
+** sorted.  As long as rows are sorted for just the innermost loop, this
+** routine can return TRUE.
+*/
+SQLITE_PRIVATE int sqlite3WhereOrderedInnerLoop(WhereInfo *pWInfo){
+  return pWInfo->bOrderedInnerLoop;
+}
+
+/*
+** Return the VDBE address or label to jump to in order to continue
+** immediately with the next row of a WHERE clause.
+*/
+SQLITE_PRIVATE int sqlite3WhereContinueLabel(WhereInfo *pWInfo){
+  assert( pWInfo->iContinue!=0 );
+  return pWInfo->iContinue;
+}
+
+/*
+** Return the VDBE address or label to jump to in order to break
+** out of a WHERE loop.
+*/
+SQLITE_PRIVATE int sqlite3WhereBreakLabel(WhereInfo *pWInfo){
+  return pWInfo->iBreak;
+}
+
+/*
+** Return ONEPASS_OFF (0) if an UPDATE or DELETE statement is unable to
+** operate directly on the rowis returned by a WHERE clause.  Return
+** ONEPASS_SINGLE (1) if the statement can operation directly because only
+** a single row is to be changed.  Return ONEPASS_MULTI (2) if the one-pass
+** optimization can be used on multiple 
+**
+** If the ONEPASS optimization is used (if this routine returns true)
+** then also write the indices of open cursors used by ONEPASS
+** into aiCur[0] and aiCur[1].  iaCur[0] gets the cursor of the data
+** table and iaCur[1] gets the cursor used by an auxiliary index.
+** Either value may be -1, indicating that cursor is not used.
+** Any cursors returned will have been opened for writing.
+**
+** aiCur[0] and aiCur[1] both get -1 if the where-clause logic is
+** unable to use the ONEPASS optimization.
+*/
+SQLITE_PRIVATE int sqlite3WhereOkOnePass(WhereInfo *pWInfo, int *aiCur){
+  memcpy(aiCur, pWInfo->aiCurOnePass, sizeof(int)*2);
+#ifdef WHERETRACE_ENABLED
+  if( sqlite3WhereTrace && pWInfo->eOnePass!=ONEPASS_OFF ){
+    sqlite3DebugPrintf("%s cursors: %d %d\n",
+         pWInfo->eOnePass==ONEPASS_SINGLE ? "ONEPASS_SINGLE" : "ONEPASS_MULTI",
+         aiCur[0], aiCur[1]);
+  }
+#endif
+  return pWInfo->eOnePass;
+}
+
+/*
+** Move the content of pSrc into pDest
+*/
+static void whereOrMove(WhereOrSet *pDest, WhereOrSet *pSrc){
+  pDest->n = pSrc->n;
+  memcpy(pDest->a, pSrc->a, pDest->n*sizeof(pDest->a[0]));
+}
+
+/*
+** Try to insert a new prerequisite/cost entry into the WhereOrSet pSet.
+**
+** The new entry might overwrite an existing entry, or it might be
+** appended, or it might be discarded.  Do whatever is the right thing
+** so that pSet keeps the N_OR_COST best entries seen so far.
+*/
+static int whereOrInsert(
+  WhereOrSet *pSet,      /* The WhereOrSet to be updated */
+  Bitmask prereq,        /* Prerequisites of the new entry */
+  LogEst rRun,           /* Run-cost of the new entry */
+  LogEst nOut            /* Number of outputs for the new entry */
+){
+  u16 i;
+  WhereOrCost *p;
+  for(i=pSet->n, p=pSet->a; i>0; i--, p++){
+    if( rRun<=p->rRun && (prereq & p->prereq)==prereq ){
+      goto whereOrInsert_done;
+    }
+    if( p->rRun<=rRun && (p->prereq & prereq)==p->prereq ){
+      return 0;
+    }
+  }
+  if( pSet->n<N_OR_COST ){
+    p = &pSet->a[pSet->n++];
+    p->nOut = nOut;
+  }else{
+    p = pSet->a;
+    for(i=1; i<pSet->n; i++){
+      if( p->rRun>pSet->a[i].rRun ) p = pSet->a + i;
+    }
+    if( p->rRun<=rRun ) return 0;
+  }
+whereOrInsert_done:
+  p->prereq = prereq;
+  p->rRun = rRun;
+  if( p->nOut>nOut ) p->nOut = nOut;
+  return 1;
+}
+
+/*
+** Return the bitmask for the given cursor number.  Return 0 if
+** iCursor is not in the set.
+*/
+SQLITE_PRIVATE Bitmask sqlite3WhereGetMask(WhereMaskSet *pMaskSet, int iCursor){
+  int i;
+  assert( pMaskSet->n<=(int)sizeof(Bitmask)*8 );
+  for(i=0; i<pMaskSet->n; i++){
+    if( pMaskSet->ix[i]==iCursor ){
+      return MASKBIT(i);
+    }
+  }
+  return 0;
+}
+
+/*
+** Create a new mask for cursor iCursor.
+**
+** There is one cursor per table in the FROM clause.  The number of
+** tables in the FROM clause is limited by a test early in the
+** sqlite3WhereBegin() routine.  So we know that the pMaskSet->ix[]
+** array will never overflow.
+*/
+static void createMask(WhereMaskSet *pMaskSet, int iCursor){
+  assert( pMaskSet->n < ArraySize(pMaskSet->ix) );
+  pMaskSet->ix[pMaskSet->n++] = iCursor;
+}
+
+/*
+** Advance to the next WhereTerm that matches according to the criteria
+** established when the pScan object was initialized by whereScanInit().
+** Return NULL if there are no more matching WhereTerms.
+*/
+static WhereTerm *whereScanNext(WhereScan *pScan){
+  int iCur;            /* The cursor on the LHS of the term */
+  i16 iColumn;         /* The column on the LHS of the term.  -1 for IPK */
+  Expr *pX;            /* An expression being tested */
+  WhereClause *pWC;    /* Shorthand for pScan->pWC */
+  WhereTerm *pTerm;    /* The term being tested */
+  int k = pScan->k;    /* Where to start scanning */
+
+  while( pScan->iEquiv<=pScan->nEquiv ){
+    iCur = pScan->aiCur[pScan->iEquiv-1];
+    iColumn = pScan->aiColumn[pScan->iEquiv-1];
+    if( iColumn==XN_EXPR && pScan->pIdxExpr==0 ) return 0;
+    while( (pWC = pScan->pWC)!=0 ){
+      for(pTerm=pWC->a+k; k<pWC->nTerm; k++, pTerm++){
+        if( pTerm->leftCursor==iCur
+         && pTerm->u.leftColumn==iColumn
+         && (iColumn!=XN_EXPR
+             || sqlite3ExprCompare(pTerm->pExpr->pLeft,pScan->pIdxExpr,iCur)==0)
+         && (pScan->iEquiv<=1 || !ExprHasProperty(pTerm->pExpr, EP_FromJoin))
+        ){
+          if( (pTerm->eOperator & WO_EQUIV)!=0
+           && pScan->nEquiv<ArraySize(pScan->aiCur)
+           && (pX = sqlite3ExprSkipCollate(pTerm->pExpr->pRight))->op==TK_COLUMN
+          ){
+            int j;
+            for(j=0; j<pScan->nEquiv; j++){
+              if( pScan->aiCur[j]==pX->iTable
+               && pScan->aiColumn[j]==pX->iColumn ){
+                  break;
+              }
+            }
+            if( j==pScan->nEquiv ){
+              pScan->aiCur[j] = pX->iTable;
+              pScan->aiColumn[j] = pX->iColumn;
+              pScan->nEquiv++;
+            }
+          }
+          if( (pTerm->eOperator & pScan->opMask)!=0 ){
+            /* Verify the affinity and collating sequence match */
+            if( pScan->zCollName && (pTerm->eOperator & WO_ISNULL)==0 ){
+              CollSeq *pColl;
+              Parse *pParse = pWC->pWInfo->pParse;
+              pX = pTerm->pExpr;
+              if( !sqlite3IndexAffinityOk(pX, pScan->idxaff) ){
+                continue;
+              }
+              assert(pX->pLeft);
+              pColl = sqlite3BinaryCompareCollSeq(pParse,
+                                                  pX->pLeft, pX->pRight);
+              if( pColl==0 ) pColl = pParse->db->pDfltColl;
+              if( sqlite3StrICmp(pColl->zName, pScan->zCollName) ){
+                continue;
+              }
+            }
+            if( (pTerm->eOperator & (WO_EQ|WO_IS))!=0
+             && (pX = pTerm->pExpr->pRight)->op==TK_COLUMN
+             && pX->iTable==pScan->aiCur[0]
+             && pX->iColumn==pScan->aiColumn[0]
+            ){
+              testcase( pTerm->eOperator & WO_IS );
+              continue;
+            }
+            pScan->k = k+1;
+            return pTerm;
+          }
+        }
+      }
+      pScan->pWC = pScan->pWC->pOuter;
+      k = 0;
+    }
+    pScan->pWC = pScan->pOrigWC;
+    k = 0;
+    pScan->iEquiv++;
+  }
+  return 0;
+}
+
+/*
+** Initialize a WHERE clause scanner object.  Return a pointer to the
+** first match.  Return NULL if there are no matches.
+**
+** The scanner will be searching the WHERE clause pWC.  It will look
+** for terms of the form "X <op> <expr>" where X is column iColumn of table
+** iCur.   Or if pIdx!=0 then X is column iColumn of index pIdx.  pIdx
+** must be one of the indexes of table iCur.
+**
+** The <op> must be one of the operators described by opMask.
+**
+** If the search is for X and the WHERE clause contains terms of the
+** form X=Y then this routine might also return terms of the form
+** "Y <op> <expr>".  The number of levels of transitivity is limited,
+** but is enough to handle most commonly occurring SQL statements.
+**
+** If X is not the INTEGER PRIMARY KEY then X must be compatible with
+** index pIdx.
+*/
+static WhereTerm *whereScanInit(
+  WhereScan *pScan,       /* The WhereScan object being initialized */
+  WhereClause *pWC,       /* The WHERE clause to be scanned */
+  int iCur,               /* Cursor to scan for */
+  int iColumn,            /* Column to scan for */
+  u32 opMask,             /* Operator(s) to scan for */
+  Index *pIdx             /* Must be compatible with this index */
+){
+  int j = 0;
+
+  /* memset(pScan, 0, sizeof(*pScan)); */
+  pScan->pOrigWC = pWC;
+  pScan->pWC = pWC;
+  pScan->pIdxExpr = 0;
+  if( pIdx ){
+    j = iColumn;
+    iColumn = pIdx->aiColumn[j];
+    if( iColumn==XN_EXPR ) pScan->pIdxExpr = pIdx->aColExpr->a[j].pExpr;
+    if( iColumn==pIdx->pTable->iPKey ) iColumn = XN_ROWID;
+  }
+  if( pIdx && iColumn>=0 ){
+    pScan->idxaff = pIdx->pTable->aCol[iColumn].affinity;
+    pScan->zCollName = pIdx->azColl[j];
+  }else{
+    pScan->idxaff = 0;
+    pScan->zCollName = 0;
+  }
+  pScan->opMask = opMask;
+  pScan->k = 0;
+  pScan->aiCur[0] = iCur;
+  pScan->aiColumn[0] = iColumn;
+  pScan->nEquiv = 1;
+  pScan->iEquiv = 1;
+  return whereScanNext(pScan);
+}
+
+/*
+** Search for a term in the WHERE clause that is of the form "X <op> <expr>"
+** where X is a reference to the iColumn of table iCur or of index pIdx
+** if pIdx!=0 and <op> is one of the WO_xx operator codes specified by
+** the op parameter.  Return a pointer to the term.  Return 0 if not found.
+**
+** If pIdx!=0 then it must be one of the indexes of table iCur.  
+** Search for terms matching the iColumn-th column of pIdx
+** rather than the iColumn-th column of table iCur.
+**
+** The term returned might by Y=<expr> if there is another constraint in
+** the WHERE clause that specifies that X=Y.  Any such constraints will be
+** identified by the WO_EQUIV bit in the pTerm->eOperator field.  The
+** aiCur[]/iaColumn[] arrays hold X and all its equivalents. There are 11
+** slots in aiCur[]/aiColumn[] so that means we can look for X plus up to 10
+** other equivalent values.  Hence a search for X will return <expr> if X=A1
+** and A1=A2 and A2=A3 and ... and A9=A10 and A10=<expr>.
+**
+** If there are multiple terms in the WHERE clause of the form "X <op> <expr>"
+** then try for the one with no dependencies on <expr> - in other words where
+** <expr> is a constant expression of some kind.  Only return entries of
+** the form "X <op> Y" where Y is a column in another table if no terms of
+** the form "X <op> <const-expr>" exist.   If no terms with a constant RHS
+** exist, try to return a term that does not use WO_EQUIV.
+*/
+SQLITE_PRIVATE WhereTerm *sqlite3WhereFindTerm(
+  WhereClause *pWC,     /* The WHERE clause to be searched */
+  int iCur,             /* Cursor number of LHS */
+  int iColumn,          /* Column number of LHS */
+  Bitmask notReady,     /* RHS must not overlap with this mask */
+  u32 op,               /* Mask of WO_xx values describing operator */
+  Index *pIdx           /* Must be compatible with this index, if not NULL */
+){
+  WhereTerm *pResult = 0;
+  WhereTerm *p;
+  WhereScan scan;
+
+  p = whereScanInit(&scan, pWC, iCur, iColumn, op, pIdx);
+  op &= WO_EQ|WO_IS;
+  while( p ){
+    if( (p->prereqRight & notReady)==0 ){
+      if( p->prereqRight==0 && (p->eOperator&op)!=0 ){
+        testcase( p->eOperator & WO_IS );
+        return p;
+      }
+      if( pResult==0 ) pResult = p;
+    }
+    p = whereScanNext(&scan);
+  }
+  return pResult;
+}
+
+/*
+** This function searches pList for an entry that matches the iCol-th column
+** of index pIdx.
+**
+** If such an expression is found, its index in pList->a[] is returned. If
+** no expression is found, -1 is returned.
+*/
+static int findIndexCol(
+  Parse *pParse,                  /* Parse context */
+  ExprList *pList,                /* Expression list to search */
+  int iBase,                      /* Cursor for table associated with pIdx */
+  Index *pIdx,                    /* Index to match column of */
+  int iCol                        /* Column of index to match */
+){
+  int i;
+  const char *zColl = pIdx->azColl[iCol];
+
+  for(i=0; i<pList->nExpr; i++){
+    Expr *p = sqlite3ExprSkipCollate(pList->a[i].pExpr);
+    if( p->op==TK_COLUMN
+     && p->iColumn==pIdx->aiColumn[iCol]
+     && p->iTable==iBase
+    ){
+      CollSeq *pColl = sqlite3ExprCollSeq(pParse, pList->a[i].pExpr);
+      if( pColl && 0==sqlite3StrICmp(pColl->zName, zColl) ){
+        return i;
+      }
+    }
+  }
+
+  return -1;
+}
+
+/*
+** Return TRUE if the iCol-th column of index pIdx is NOT NULL
+*/
+static int indexColumnNotNull(Index *pIdx, int iCol){
+  int j;
+  assert( pIdx!=0 );
+  assert( iCol>=0 && iCol<pIdx->nColumn );
+  j = pIdx->aiColumn[iCol];
+  if( j>=0 ){
+    return pIdx->pTable->aCol[j].notNull;
+  }else if( j==(-1) ){
+    return 1;
+  }else{
+    assert( j==(-2) );
+    return 0;  /* Assume an indexed expression can always yield a NULL */
+
+  }
+}
+
+/*
+** Return true if the DISTINCT expression-list passed as the third argument
+** is redundant.
+**
+** A DISTINCT list is redundant if any subset of the columns in the
+** DISTINCT list are collectively unique and individually non-null.
+*/
+static int isDistinctRedundant(
+  Parse *pParse,            /* Parsing context */
+  SrcList *pTabList,        /* The FROM clause */
+  WhereClause *pWC,         /* The WHERE clause */
+  ExprList *pDistinct       /* The result set that needs to be DISTINCT */
+){
+  Table *pTab;
+  Index *pIdx;
+  int i;                          
+  int iBase;
+
+  /* If there is more than one table or sub-select in the FROM clause of
+  ** this query, then it will not be possible to show that the DISTINCT 
+  ** clause is redundant. */
+  if( pTabList->nSrc!=1 ) return 0;
+  iBase = pTabList->a[0].iCursor;
+  pTab = pTabList->a[0].pTab;
+
+  /* If any of the expressions is an IPK column on table iBase, then return 
+  ** true. Note: The (p->iTable==iBase) part of this test may be false if the
+  ** current SELECT is a correlated sub-query.
+  */
+  for(i=0; i<pDistinct->nExpr; i++){
+    Expr *p = sqlite3ExprSkipCollate(pDistinct->a[i].pExpr);
+    if( p->op==TK_COLUMN && p->iTable==iBase && p->iColumn<0 ) return 1;
+  }
+
+  /* Loop through all indices on the table, checking each to see if it makes
+  ** the DISTINCT qualifier redundant. It does so if:
+  **
+  **   1. The index is itself UNIQUE, and
+  **
+  **   2. All of the columns in the index are either part of the pDistinct
+  **      list, or else the WHERE clause contains a term of the form "col=X",
+  **      where X is a constant value. The collation sequences of the
+  **      comparison and select-list expressions must match those of the index.
+  **
+  **   3. All of those index columns for which the WHERE clause does not
+  **      contain a "col=X" term are subject to a NOT NULL constraint.
+  */
+  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+    if( !IsUniqueIndex(pIdx) ) continue;
+    for(i=0; i<pIdx->nKeyCol; i++){
+      if( 0==sqlite3WhereFindTerm(pWC, iBase, i, ~(Bitmask)0, WO_EQ, pIdx) ){
+        if( findIndexCol(pParse, pDistinct, iBase, pIdx, i)<0 ) break;
+        if( indexColumnNotNull(pIdx, i)==0 ) break;
+      }
+    }
+    if( i==pIdx->nKeyCol ){
+      /* This index implies that the DISTINCT qualifier is redundant. */
+      return 1;
+    }
+  }
+
+  return 0;
+}
+
+
+/*
+** Estimate the logarithm of the input value to base 2.
+*/
+static LogEst estLog(LogEst N){
+  return N<=10 ? 0 : sqlite3LogEst(N) - 33;
+}
+
+/*
+** Convert OP_Column opcodes to OP_Copy in previously generated code.
+**
+** This routine runs over generated VDBE code and translates OP_Column
+** opcodes into OP_Copy when the table is being accessed via co-routine 
+** instead of via table lookup.
+**
+** If the bIncrRowid parameter is 0, then any OP_Rowid instructions on
+** cursor iTabCur are transformed into OP_Null. Or, if bIncrRowid is non-zero,
+** then each OP_Rowid is transformed into an instruction to increment the
+** value stored in its output register.
+*/
+static void translateColumnToCopy(
+  Vdbe *v,            /* The VDBE containing code to translate */
+  int iStart,         /* Translate from this opcode to the end */
+  int iTabCur,        /* OP_Column/OP_Rowid references to this table */
+  int iRegister,      /* The first column is in this register */
+  int bIncrRowid      /* If non-zero, transform OP_rowid to OP_AddImm(1) */
+){
+  VdbeOp *pOp = sqlite3VdbeGetOp(v, iStart);
+  int iEnd = sqlite3VdbeCurrentAddr(v);
+  for(; iStart<iEnd; iStart++, pOp++){
+    if( pOp->p1!=iTabCur ) continue;
+    if( pOp->opcode==OP_Column ){
+      pOp->opcode = OP_Copy;
+      pOp->p1 = pOp->p2 + iRegister;
+      pOp->p2 = pOp->p3;
+      pOp->p3 = 0;
+    }else if( pOp->opcode==OP_Rowid ){
+      if( bIncrRowid ){
+        /* Increment the value stored in the P2 operand of the OP_Rowid. */
+        pOp->opcode = OP_AddImm;
+        pOp->p1 = pOp->p2;
+        pOp->p2 = 1;
+      }else{
+        pOp->opcode = OP_Null;
+        pOp->p1 = 0;
+        pOp->p3 = 0;
+      }
+    }
+  }
+}
+
+/*
+** Two routines for printing the content of an sqlite3_index_info
+** structure.  Used for testing and debugging only.  If neither
+** SQLITE_TEST or SQLITE_DEBUG are defined, then these routines
+** are no-ops.
+*/
+#if !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(WHERETRACE_ENABLED)
+static void TRACE_IDX_INPUTS(sqlite3_index_info *p){
+  int i;
+  if( !sqlite3WhereTrace ) return;
+  for(i=0; i<p->nConstraint; i++){
+    sqlite3DebugPrintf("  constraint[%d]: col=%d termid=%d op=%d usabled=%d\n",
+       i,
+       p->aConstraint[i].iColumn,
+       p->aConstraint[i].iTermOffset,
+       p->aConstraint[i].op,
+       p->aConstraint[i].usable);
+  }
+  for(i=0; i<p->nOrderBy; i++){
+    sqlite3DebugPrintf("  orderby[%d]: col=%d desc=%d\n",
+       i,
+       p->aOrderBy[i].iColumn,
+       p->aOrderBy[i].desc);
+  }
+}
+static void TRACE_IDX_OUTPUTS(sqlite3_index_info *p){
+  int i;
+  if( !sqlite3WhereTrace ) return;
+  for(i=0; i<p->nConstraint; i++){
+    sqlite3DebugPrintf("  usage[%d]: argvIdx=%d omit=%d\n",
+       i,
+       p->aConstraintUsage[i].argvIndex,
+       p->aConstraintUsage[i].omit);
+  }
+  sqlite3DebugPrintf("  idxNum=%d\n", p->idxNum);
+  sqlite3DebugPrintf("  idxStr=%s\n", p->idxStr);
+  sqlite3DebugPrintf("  orderByConsumed=%d\n", p->orderByConsumed);
+  sqlite3DebugPrintf("  estimatedCost=%g\n", p->estimatedCost);
+  sqlite3DebugPrintf("  estimatedRows=%lld\n", p->estimatedRows);
+}
+#else
+#define TRACE_IDX_INPUTS(A)
+#define TRACE_IDX_OUTPUTS(A)
+#endif
+
+#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
+/*
+** Return TRUE if the WHERE clause term pTerm is of a form where it
+** could be used with an index to access pSrc, assuming an appropriate
+** index existed.
+*/
+static int termCanDriveIndex(
+  WhereTerm *pTerm,              /* WHERE clause term to check */
+  struct SrcList_item *pSrc,     /* Table we are trying to access */
+  Bitmask notReady               /* Tables in outer loops of the join */
+){
+  char aff;
+  if( pTerm->leftCursor!=pSrc->iCursor ) return 0;
+  if( (pTerm->eOperator & (WO_EQ|WO_IS))==0 ) return 0;
+  if( (pTerm->prereqRight & notReady)!=0 ) return 0;
+  if( pTerm->u.leftColumn<0 ) return 0;
+  aff = pSrc->pTab->aCol[pTerm->u.leftColumn].affinity;
+  if( !sqlite3IndexAffinityOk(pTerm->pExpr, aff) ) return 0;
+  testcase( pTerm->pExpr->op==TK_IS );
+  return 1;
+}
+#endif
+
+
+#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
+/*
+** Generate code to construct the Index object for an automatic index
+** and to set up the WhereLevel object pLevel so that the code generator
+** makes use of the automatic index.
+*/
+static void constructAutomaticIndex(
+  Parse *pParse,              /* The parsing context */
+  WhereClause *pWC,           /* The WHERE clause */
+  struct SrcList_item *pSrc,  /* The FROM clause term to get the next index */
+  Bitmask notReady,           /* Mask of cursors that are not available */
+  WhereLevel *pLevel          /* Write new index here */
+){
+  int nKeyCol;                /* Number of columns in the constructed index */
+  WhereTerm *pTerm;           /* A single term of the WHERE clause */
+  WhereTerm *pWCEnd;          /* End of pWC->a[] */
+  Index *pIdx;                /* Object describing the transient index */
+  Vdbe *v;                    /* Prepared statement under construction */
+  int addrInit;               /* Address of the initialization bypass jump */
+  Table *pTable;              /* The table being indexed */
+  int addrTop;                /* Top of the index fill loop */
+  int regRecord;              /* Register holding an index record */
+  int n;                      /* Column counter */
+  int i;                      /* Loop counter */
+  int mxBitCol;               /* Maximum column in pSrc->colUsed */
+  CollSeq *pColl;             /* Collating sequence to on a column */
+  WhereLoop *pLoop;           /* The Loop object */
+  char *zNotUsed;             /* Extra space on the end of pIdx */
+  Bitmask idxCols;            /* Bitmap of columns used for indexing */
+  Bitmask extraCols;          /* Bitmap of additional columns */
+  u8 sentWarning = 0;         /* True if a warnning has been issued */
+  Expr *pPartial = 0;         /* Partial Index Expression */
+  int iContinue = 0;          /* Jump here to skip excluded rows */
+  struct SrcList_item *pTabItem;  /* FROM clause term being indexed */
+  int addrCounter = 0;        /* Address where integer counter is initialized */
+  int regBase;                /* Array of registers where record is assembled */
+
+  /* Generate code to skip over the creation and initialization of the
+  ** transient index on 2nd and subsequent iterations of the loop. */
+  v = pParse->pVdbe;
+  assert( v!=0 );
+  addrInit = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
+
+  /* Count the number of columns that will be added to the index
+  ** and used to match WHERE clause constraints */
+  nKeyCol = 0;
+  pTable = pSrc->pTab;
+  pWCEnd = &pWC->a[pWC->nTerm];
+  pLoop = pLevel->pWLoop;
+  idxCols = 0;
+  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
+    Expr *pExpr = pTerm->pExpr;
+    assert( !ExprHasProperty(pExpr, EP_FromJoin)    /* prereq always non-zero */
+         || pExpr->iRightJoinTable!=pSrc->iCursor   /*   for the right-hand   */
+         || pLoop->prereq!=0 );                     /*   table of a LEFT JOIN */
+    if( pLoop->prereq==0
+     && (pTerm->wtFlags & TERM_VIRTUAL)==0
+     && !ExprHasProperty(pExpr, EP_FromJoin)
+     && sqlite3ExprIsTableConstant(pExpr, pSrc->iCursor) ){
+      pPartial = sqlite3ExprAnd(pParse->db, pPartial,
+                                sqlite3ExprDup(pParse->db, pExpr, 0));
+    }
+    if( termCanDriveIndex(pTerm, pSrc, notReady) ){
+      int iCol = pTerm->u.leftColumn;
+      Bitmask cMask = iCol>=BMS ? MASKBIT(BMS-1) : MASKBIT(iCol);
+      testcase( iCol==BMS );
+      testcase( iCol==BMS-1 );
+      if( !sentWarning ){
+        sqlite3_log(SQLITE_WARNING_AUTOINDEX,
+            "automatic index on %s(%s)", pTable->zName,
+            pTable->aCol[iCol].zName);
+        sentWarning = 1;
+      }
+      if( (idxCols & cMask)==0 ){
+        if( whereLoopResize(pParse->db, pLoop, nKeyCol+1) ){
+          goto end_auto_index_create;
+        }
+        pLoop->aLTerm[nKeyCol++] = pTerm;
+        idxCols |= cMask;
+      }
+    }
+  }
+  assert( nKeyCol>0 );
+  pLoop->u.btree.nEq = pLoop->nLTerm = nKeyCol;
+  pLoop->wsFlags = WHERE_COLUMN_EQ | WHERE_IDX_ONLY | WHERE_INDEXED
+                     | WHERE_AUTO_INDEX;
+
+  /* Count the number of additional columns needed to create a
+  ** covering index.  A "covering index" is an index that contains all
+  ** columns that are needed by the query.  With a covering index, the
+  ** original table never needs to be accessed.  Automatic indices must
+  ** be a covering index because the index will not be updated if the
+  ** original table changes and the index and table cannot both be used
+  ** if they go out of sync.
+  */
+  extraCols = pSrc->colUsed & (~idxCols | MASKBIT(BMS-1));
+  mxBitCol = MIN(BMS-1,pTable->nCol);
+  testcase( pTable->nCol==BMS-1 );
+  testcase( pTable->nCol==BMS-2 );
+  for(i=0; i<mxBitCol; i++){
+    if( extraCols & MASKBIT(i) ) nKeyCol++;
+  }
+  if( pSrc->colUsed & MASKBIT(BMS-1) ){
+    nKeyCol += pTable->nCol - BMS + 1;
+  }
+
+  /* Construct the Index object to describe this index */
+  pIdx = sqlite3AllocateIndexObject(pParse->db, nKeyCol+1, 0, &zNotUsed);
+  if( pIdx==0 ) goto end_auto_index_create;
+  pLoop->u.btree.pIndex = pIdx;
+  pIdx->zName = "auto-index";
+  pIdx->pTable = pTable;
+  n = 0;
+  idxCols = 0;
+  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
+    if( termCanDriveIndex(pTerm, pSrc, notReady) ){
+      int iCol = pTerm->u.leftColumn;
+      Bitmask cMask = iCol>=BMS ? MASKBIT(BMS-1) : MASKBIT(iCol);
+      testcase( iCol==BMS-1 );
+      testcase( iCol==BMS );
+      if( (idxCols & cMask)==0 ){
+        Expr *pX = pTerm->pExpr;
+        idxCols |= cMask;
+        pIdx->aiColumn[n] = pTerm->u.leftColumn;
+        pColl = sqlite3BinaryCompareCollSeq(pParse, pX->pLeft, pX->pRight);
+        pIdx->azColl[n] = pColl ? pColl->zName : sqlite3StrBINARY;
+        n++;
+      }
+    }
+  }
+  assert( (u32)n==pLoop->u.btree.nEq );
+
+  /* Add additional columns needed to make the automatic index into
+  ** a covering index */
+  for(i=0; i<mxBitCol; i++){
+    if( extraCols & MASKBIT(i) ){
+      pIdx->aiColumn[n] = i;
+      pIdx->azColl[n] = sqlite3StrBINARY;
+      n++;
+    }
+  }
+  if( pSrc->colUsed & MASKBIT(BMS-1) ){
+    for(i=BMS-1; i<pTable->nCol; i++){
+      pIdx->aiColumn[n] = i;
+      pIdx->azColl[n] = sqlite3StrBINARY;
+      n++;
+    }
+  }
+  assert( n==nKeyCol );
+  pIdx->aiColumn[n] = XN_ROWID;
+  pIdx->azColl[n] = sqlite3StrBINARY;
+
+  /* Create the automatic index */
+  assert( pLevel->iIdxCur>=0 );
+  pLevel->iIdxCur = pParse->nTab++;
+  sqlite3VdbeAddOp2(v, OP_OpenAutoindex, pLevel->iIdxCur, nKeyCol+1);
+  sqlite3VdbeSetP4KeyInfo(pParse, pIdx);
+  VdbeComment((v, "for %s", pTable->zName));
+
+  /* Fill the automatic index with content */
+  sqlite3ExprCachePush(pParse);
+  pTabItem = &pWC->pWInfo->pTabList->a[pLevel->iFrom];
+  if( pTabItem->fg.viaCoroutine ){
+    int regYield = pTabItem->regReturn;
+    addrCounter = sqlite3VdbeAddOp2(v, OP_Integer, 0, 0);
+    sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, pTabItem->addrFillSub);
+    addrTop =  sqlite3VdbeAddOp1(v, OP_Yield, regYield);
+    VdbeCoverage(v);
+    VdbeComment((v, "next row of \"%s\"", pTabItem->pTab->zName));
+  }else{
+    addrTop = sqlite3VdbeAddOp1(v, OP_Rewind, pLevel->iTabCur); VdbeCoverage(v);
+  }
+  if( pPartial ){
+    iContinue = sqlite3VdbeMakeLabel(v);
+    sqlite3ExprIfFalse(pParse, pPartial, iContinue, SQLITE_JUMPIFNULL);
+    pLoop->wsFlags |= WHERE_PARTIALIDX;
+  }
+  regRecord = sqlite3GetTempReg(pParse);
+  regBase = sqlite3GenerateIndexKey(
+      pParse, pIdx, pLevel->iTabCur, regRecord, 0, 0, 0, 0
+  );
+  sqlite3VdbeAddOp2(v, OP_IdxInsert, pLevel->iIdxCur, regRecord);
+  sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
+  if( pPartial ) sqlite3VdbeResolveLabel(v, iContinue);
+  if( pTabItem->fg.viaCoroutine ){
+    sqlite3VdbeChangeP2(v, addrCounter, regBase+n);
+    translateColumnToCopy(v, addrTop, pLevel->iTabCur, pTabItem->regResult, 1);
+    sqlite3VdbeGoto(v, addrTop);
+    pTabItem->fg.viaCoroutine = 0;
+  }else{
+    sqlite3VdbeAddOp2(v, OP_Next, pLevel->iTabCur, addrTop+1); VdbeCoverage(v);
+  }
+  sqlite3VdbeChangeP5(v, SQLITE_STMTSTATUS_AUTOINDEX);
+  sqlite3VdbeJumpHere(v, addrTop);
+  sqlite3ReleaseTempReg(pParse, regRecord);
+  sqlite3ExprCachePop(pParse);
+  
+  /* Jump here when skipping the initialization */
+  sqlite3VdbeJumpHere(v, addrInit);
+
+end_auto_index_create:
+  sqlite3ExprDelete(pParse->db, pPartial);
+}
+#endif /* SQLITE_OMIT_AUTOMATIC_INDEX */
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/*
+** Allocate and populate an sqlite3_index_info structure. It is the 
+** responsibility of the caller to eventually release the structure
+** by passing the pointer returned by this function to sqlite3_free().
+*/
+static sqlite3_index_info *allocateIndexInfo(
+  Parse *pParse,
+  WhereClause *pWC,
+  Bitmask mUnusable,              /* Ignore terms with these prereqs */
+  struct SrcList_item *pSrc,
+  ExprList *pOrderBy,
+  u16 *pmNoOmit                   /* Mask of terms not to omit */
+){
+  int i, j;
+  int nTerm;
+  struct sqlite3_index_constraint *pIdxCons;
+  struct sqlite3_index_orderby *pIdxOrderBy;
+  struct sqlite3_index_constraint_usage *pUsage;
+  WhereTerm *pTerm;
+  int nOrderBy;
+  sqlite3_index_info *pIdxInfo;
+  u16 mNoOmit = 0;
+
+  /* Count the number of possible WHERE clause constraints referring
+  ** to this virtual table */
+  for(i=nTerm=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
+    if( pTerm->leftCursor != pSrc->iCursor ) continue;
+    if( pTerm->prereqRight & mUnusable ) continue;
+    assert( IsPowerOfTwo(pTerm->eOperator & ~WO_EQUIV) );
+    testcase( pTerm->eOperator & WO_IN );
+    testcase( pTerm->eOperator & WO_ISNULL );
+    testcase( pTerm->eOperator & WO_IS );
+    testcase( pTerm->eOperator & WO_ALL );
+    if( (pTerm->eOperator & ~(WO_ISNULL|WO_EQUIV|WO_IS))==0 ) continue;
+    if( pTerm->wtFlags & TERM_VNULL ) continue;
+    assert( pTerm->u.leftColumn>=(-1) );
+    nTerm++;
+  }
+
+  /* If the ORDER BY clause contains only columns in the current 
+  ** virtual table then allocate space for the aOrderBy part of
+  ** the sqlite3_index_info structure.
+  */
+  nOrderBy = 0;
+  if( pOrderBy ){
+    int n = pOrderBy->nExpr;
+    for(i=0; i<n; i++){
+      Expr *pExpr = pOrderBy->a[i].pExpr;
+      if( pExpr->op!=TK_COLUMN || pExpr->iTable!=pSrc->iCursor ) break;
+    }
+    if( i==n){
+      nOrderBy = n;
+    }
+  }
+
+  /* Allocate the sqlite3_index_info structure
+  */
+  pIdxInfo = sqlite3DbMallocZero(pParse->db, sizeof(*pIdxInfo)
+                           + (sizeof(*pIdxCons) + sizeof(*pUsage))*nTerm
+                           + sizeof(*pIdxOrderBy)*nOrderBy );
+  if( pIdxInfo==0 ){
+    sqlite3ErrorMsg(pParse, "out of memory");
+    return 0;
+  }
+
+  /* Initialize the structure.  The sqlite3_index_info structure contains
+  ** many fields that are declared "const" to prevent xBestIndex from
+  ** changing them.  We have to do some funky casting in order to
+  ** initialize those fields.
+  */
+  pIdxCons = (struct sqlite3_index_constraint*)&pIdxInfo[1];
+  pIdxOrderBy = (struct sqlite3_index_orderby*)&pIdxCons[nTerm];
+  pUsage = (struct sqlite3_index_constraint_usage*)&pIdxOrderBy[nOrderBy];
+  *(int*)&pIdxInfo->nConstraint = nTerm;
+  *(int*)&pIdxInfo->nOrderBy = nOrderBy;
+  *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint = pIdxCons;
+  *(struct sqlite3_index_orderby**)&pIdxInfo->aOrderBy = pIdxOrderBy;
+  *(struct sqlite3_index_constraint_usage**)&pIdxInfo->aConstraintUsage =
+                                                                   pUsage;
+
+  for(i=j=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
+    u8 op;
+    if( pTerm->leftCursor != pSrc->iCursor ) continue;
+    if( pTerm->prereqRight & mUnusable ) continue;
+    assert( IsPowerOfTwo(pTerm->eOperator & ~WO_EQUIV) );
+    testcase( pTerm->eOperator & WO_IN );
+    testcase( pTerm->eOperator & WO_IS );
+    testcase( pTerm->eOperator & WO_ISNULL );
+    testcase( pTerm->eOperator & WO_ALL );
+    if( (pTerm->eOperator & ~(WO_ISNULL|WO_EQUIV|WO_IS))==0 ) continue;
+    if( pTerm->wtFlags & TERM_VNULL ) continue;
+    assert( pTerm->u.leftColumn>=(-1) );
+    pIdxCons[j].iColumn = pTerm->u.leftColumn;
+    pIdxCons[j].iTermOffset = i;
+    op = (u8)pTerm->eOperator & WO_ALL;
+    if( op==WO_IN ) op = WO_EQ;
+    if( op==WO_MATCH ){
+      op = pTerm->eMatchOp;
+    }
+    pIdxCons[j].op = op;
+    /* The direct assignment in the previous line is possible only because
+    ** the WO_ and SQLITE_INDEX_CONSTRAINT_ codes are identical.  The
+    ** following asserts verify this fact. */
+    assert( WO_EQ==SQLITE_INDEX_CONSTRAINT_EQ );
+    assert( WO_LT==SQLITE_INDEX_CONSTRAINT_LT );
+    assert( WO_LE==SQLITE_INDEX_CONSTRAINT_LE );
+    assert( WO_GT==SQLITE_INDEX_CONSTRAINT_GT );
+    assert( WO_GE==SQLITE_INDEX_CONSTRAINT_GE );
+    assert( WO_MATCH==SQLITE_INDEX_CONSTRAINT_MATCH );
+    assert( pTerm->eOperator & (WO_IN|WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE|WO_MATCH) );
+
+    if( op & (WO_LT|WO_LE|WO_GT|WO_GE)
+     && sqlite3ExprIsVector(pTerm->pExpr->pRight) 
+    ){
+      if( i<16 ) mNoOmit |= (1 << i);
+      if( op==WO_LT ) pIdxCons[j].op = WO_LE;
+      if( op==WO_GT ) pIdxCons[j].op = WO_GE;
+    }
+
+    j++;
+  }
+  for(i=0; i<nOrderBy; i++){
+    Expr *pExpr = pOrderBy->a[i].pExpr;
+    pIdxOrderBy[i].iColumn = pExpr->iColumn;
+    pIdxOrderBy[i].desc = pOrderBy->a[i].sortOrder;
+  }
+
+  *pmNoOmit = mNoOmit;
+  return pIdxInfo;
+}
+
+/*
+** The table object reference passed as the second argument to this function
+** must represent a virtual table. This function invokes the xBestIndex()
+** method of the virtual table with the sqlite3_index_info object that
+** comes in as the 3rd argument to this function.
+**
+** If an error occurs, pParse is populated with an error message and a
+** non-zero value is returned. Otherwise, 0 is returned and the output
+** part of the sqlite3_index_info structure is left populated.
+**
+** Whether or not an error is returned, it is the responsibility of the
+** caller to eventually free p->idxStr if p->needToFreeIdxStr indicates
+** that this is required.
+*/
+static int vtabBestIndex(Parse *pParse, Table *pTab, sqlite3_index_info *p){
+  sqlite3_vtab *pVtab = sqlite3GetVTable(pParse->db, pTab)->pVtab;
+  int rc;
+
+  TRACE_IDX_INPUTS(p);
+  rc = pVtab->pModule->xBestIndex(pVtab, p);
+  TRACE_IDX_OUTPUTS(p);
+
+  if( rc!=SQLITE_OK ){
+    if( rc==SQLITE_NOMEM ){
+      sqlite3OomFault(pParse->db);
+    }else if( !pVtab->zErrMsg ){
+      sqlite3ErrorMsg(pParse, "%s", sqlite3ErrStr(rc));
+    }else{
+      sqlite3ErrorMsg(pParse, "%s", pVtab->zErrMsg);
+    }
+  }
+  sqlite3_free(pVtab->zErrMsg);
+  pVtab->zErrMsg = 0;
+
+#if 0
+  /* This error is now caught by the caller.
+  ** Search for "xBestIndex malfunction" below */
+  for(i=0; i<p->nConstraint; i++){
+    if( !p->aConstraint[i].usable && p->aConstraintUsage[i].argvIndex>0 ){
+      sqlite3ErrorMsg(pParse, 
+          "table %s: xBestIndex returned an invalid plan", pTab->zName);
+    }
+  }
+#endif
+
+  return pParse->nErr;
+}
+#endif /* !defined(SQLITE_OMIT_VIRTUALTABLE) */
+
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+/*
+** Estimate the location of a particular key among all keys in an
+** index.  Store the results in aStat as follows:
+**
+**    aStat[0]      Est. number of rows less than pRec
+**    aStat[1]      Est. number of rows equal to pRec
+**
+** Return the index of the sample that is the smallest sample that
+** is greater than or equal to pRec. Note that this index is not an index
+** into the aSample[] array - it is an index into a virtual set of samples
+** based on the contents of aSample[] and the number of fields in record 
+** pRec. 
+*/
+static int whereKeyStats(
+  Parse *pParse,              /* Database connection */
+  Index *pIdx,                /* Index to consider domain of */
+  UnpackedRecord *pRec,       /* Vector of values to consider */
+  int roundUp,                /* Round up if true.  Round down if false */
+  tRowcnt *aStat              /* OUT: stats written here */
+){
+  IndexSample *aSample = pIdx->aSample;
+  int iCol;                   /* Index of required stats in anEq[] etc. */
+  int i;                      /* Index of first sample >= pRec */
+  int iSample;                /* Smallest sample larger than or equal to pRec */
+  int iMin = 0;               /* Smallest sample not yet tested */
+  int iTest;                  /* Next sample to test */
+  int res;                    /* Result of comparison operation */
+  int nField;                 /* Number of fields in pRec */
+  tRowcnt iLower = 0;         /* anLt[] + anEq[] of largest sample pRec is > */
+
+#ifndef SQLITE_DEBUG
+  UNUSED_PARAMETER( pParse );
+#endif
+  assert( pRec!=0 );
+  assert( pIdx->nSample>0 );
+  assert( pRec->nField>0 && pRec->nField<=pIdx->nSampleCol );
+
+  /* Do a binary search to find the first sample greater than or equal
+  ** to pRec. If pRec contains a single field, the set of samples to search
+  ** is simply the aSample[] array. If the samples in aSample[] contain more
+  ** than one fields, all fields following the first are ignored.
+  **
+  ** If pRec contains N fields, where N is more than one, then as well as the
+  ** samples in aSample[] (truncated to N fields), the search also has to
+  ** consider prefixes of those samples. For example, if the set of samples
+  ** in aSample is:
+  **
+  **     aSample[0] = (a, 5) 
+  **     aSample[1] = (a, 10) 
+  **     aSample[2] = (b, 5) 
+  **     aSample[3] = (c, 100) 
+  **     aSample[4] = (c, 105)
+  **
+  ** Then the search space should ideally be the samples above and the 
+  ** unique prefixes [a], [b] and [c]. But since that is hard to organize, 
+  ** the code actually searches this set:
+  **
+  **     0: (a) 
+  **     1: (a, 5) 
+  **     2: (a, 10) 
+  **     3: (a, 10) 
+  **     4: (b) 
+  **     5: (b, 5) 
+  **     6: (c) 
+  **     7: (c, 100) 
+  **     8: (c, 105)
+  **     9: (c, 105)
+  **
+  ** For each sample in the aSample[] array, N samples are present in the
+  ** effective sample array. In the above, samples 0 and 1 are based on 
+  ** sample aSample[0]. Samples 2 and 3 on aSample[1] etc.
+  **
+  ** Often, sample i of each block of N effective samples has (i+1) fields.
+  ** Except, each sample may be extended to ensure that it is greater than or
+  ** equal to the previous sample in the array. For example, in the above, 
+  ** sample 2 is the first sample of a block of N samples, so at first it 
+  ** appears that it should be 1 field in size. However, that would make it 
+  ** smaller than sample 1, so the binary search would not work. As a result, 
+  ** it is extended to two fields. The duplicates that this creates do not 
+  ** cause any problems.
+  */
+  nField = pRec->nField;
+  iCol = 0;
+  iSample = pIdx->nSample * nField;
+  do{
+    int iSamp;                    /* Index in aSample[] of test sample */
+    int n;                        /* Number of fields in test sample */
+
+    iTest = (iMin+iSample)/2;
+    iSamp = iTest / nField;
+    if( iSamp>0 ){
+      /* The proposed effective sample is a prefix of sample aSample[iSamp].
+      ** Specifically, the shortest prefix of at least (1 + iTest%nField) 
+      ** fields that is greater than the previous effective sample.  */
+      for(n=(iTest % nField) + 1; n<nField; n++){
+        if( aSample[iSamp-1].anLt[n-1]!=aSample[iSamp].anLt[n-1] ) break;
+      }
+    }else{
+      n = iTest + 1;
+    }
+
+    pRec->nField = n;
+    res = sqlite3VdbeRecordCompare(aSample[iSamp].n, aSample[iSamp].p, pRec);
+    if( res<0 ){
+      iLower = aSample[iSamp].anLt[n-1] + aSample[iSamp].anEq[n-1];
+      iMin = iTest+1;
+    }else if( res==0 && n<nField ){
+      iLower = aSample[iSamp].anLt[n-1];
+      iMin = iTest+1;
+      res = -1;
+    }else{
+      iSample = iTest;
+      iCol = n-1;
+    }
+  }while( res && iMin<iSample );
+  i = iSample / nField;
+
+#ifdef SQLITE_DEBUG
+  /* The following assert statements check that the binary search code
+  ** above found the right answer. This block serves no purpose other
+  ** than to invoke the asserts.  */
+  if( pParse->db->mallocFailed==0 ){
+    if( res==0 ){
+      /* If (res==0) is true, then pRec must be equal to sample i. */
+      assert( i<pIdx->nSample );
+      assert( iCol==nField-1 );
+      pRec->nField = nField;
+      assert( 0==sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec) 
+           || pParse->db->mallocFailed 
+      );
+    }else{
+      /* Unless i==pIdx->nSample, indicating that pRec is larger than
+      ** all samples in the aSample[] array, pRec must be smaller than the
+      ** (iCol+1) field prefix of sample i.  */
+      assert( i<=pIdx->nSample && i>=0 );
+      pRec->nField = iCol+1;
+      assert( i==pIdx->nSample 
+           || sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec)>0
+           || pParse->db->mallocFailed );
+
+      /* if i==0 and iCol==0, then record pRec is smaller than all samples
+      ** in the aSample[] array. Otherwise, if (iCol>0) then pRec must
+      ** be greater than or equal to the (iCol) field prefix of sample i.
+      ** If (i>0), then pRec must also be greater than sample (i-1).  */
+      if( iCol>0 ){
+        pRec->nField = iCol;
+        assert( sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec)<=0
+             || pParse->db->mallocFailed );
+      }
+      if( i>0 ){
+        pRec->nField = nField;
+        assert( sqlite3VdbeRecordCompare(aSample[i-1].n, aSample[i-1].p, pRec)<0
+             || pParse->db->mallocFailed );
+      }
+    }
+  }
+#endif /* ifdef SQLITE_DEBUG */
+
+  if( res==0 ){
+    /* Record pRec is equal to sample i */
+    assert( iCol==nField-1 );
+    aStat[0] = aSample[i].anLt[iCol];
+    aStat[1] = aSample[i].anEq[iCol];
+  }else{
+    /* At this point, the (iCol+1) field prefix of aSample[i] is the first 
+    ** sample that is greater than pRec. Or, if i==pIdx->nSample then pRec
+    ** is larger than all samples in the array. */
+    tRowcnt iUpper, iGap;
+    if( i>=pIdx->nSample ){
+      iUpper = sqlite3LogEstToInt(pIdx->aiRowLogEst[0]);
+    }else{
+      iUpper = aSample[i].anLt[iCol];
+    }
+
+    if( iLower>=iUpper ){
+      iGap = 0;
+    }else{
+      iGap = iUpper - iLower;
+    }
+    if( roundUp ){
+      iGap = (iGap*2)/3;
+    }else{
+      iGap = iGap/3;
+    }
+    aStat[0] = iLower + iGap;
+    aStat[1] = pIdx->aAvgEq[iCol];
+  }
+
+  /* Restore the pRec->nField value before returning.  */
+  pRec->nField = nField;
+  return i;
+}
+#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
+
+/*
+** If it is not NULL, pTerm is a term that provides an upper or lower
+** bound on a range scan. Without considering pTerm, it is estimated 
+** that the scan will visit nNew rows. This function returns the number
+** estimated to be visited after taking pTerm into account.
+**
+** If the user explicitly specified a likelihood() value for this term,
+** then the return value is the likelihood multiplied by the number of
+** input rows. Otherwise, this function assumes that an "IS NOT NULL" term
+** has a likelihood of 0.50, and any other term a likelihood of 0.25.
+*/
+static LogEst whereRangeAdjust(WhereTerm *pTerm, LogEst nNew){
+  LogEst nRet = nNew;
+  if( pTerm ){
+    if( pTerm->truthProb<=0 ){
+      nRet += pTerm->truthProb;
+    }else if( (pTerm->wtFlags & TERM_VNULL)==0 ){
+      nRet -= 20;        assert( 20==sqlite3LogEst(4) );
+    }
+  }
+  return nRet;
+}
+
+
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+/*
+** Return the affinity for a single column of an index.
+*/
+SQLITE_PRIVATE char sqlite3IndexColumnAffinity(sqlite3 *db, Index *pIdx, int iCol){
+  assert( iCol>=0 && iCol<pIdx->nColumn );
+  if( !pIdx->zColAff ){
+    if( sqlite3IndexAffinityStr(db, pIdx)==0 ) return SQLITE_AFF_BLOB;
+  }
+  return pIdx->zColAff[iCol];
+}
+#endif
+
+
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+/* 
+** This function is called to estimate the number of rows visited by a
+** range-scan on a skip-scan index. For example:
+**
+**   CREATE INDEX i1 ON t1(a, b, c);
+**   SELECT * FROM t1 WHERE a=? AND c BETWEEN ? AND ?;
+**
+** Value pLoop->nOut is currently set to the estimated number of rows 
+** visited for scanning (a=? AND b=?). This function reduces that estimate 
+** by some factor to account for the (c BETWEEN ? AND ?) expression based
+** on the stat4 data for the index. this scan will be peformed multiple 
+** times (once for each (a,b) combination that matches a=?) is dealt with 
+** by the caller.
+**
+** It does this by scanning through all stat4 samples, comparing values
+** extracted from pLower and pUpper with the corresponding column in each
+** sample. If L and U are the number of samples found to be less than or
+** equal to the values extracted from pLower and pUpper respectively, and
+** N is the total number of samples, the pLoop->nOut value is adjusted
+** as follows:
+**
+**   nOut = nOut * ( min(U - L, 1) / N )
+**
+** If pLower is NULL, or a value cannot be extracted from the term, L is
+** set to zero. If pUpper is NULL, or a value cannot be extracted from it,
+** U is set to N.
+**
+** Normally, this function sets *pbDone to 1 before returning. However,
+** if no value can be extracted from either pLower or pUpper (and so the
+** estimate of the number of rows delivered remains unchanged), *pbDone
+** is left as is.
+**
+** If an error occurs, an SQLite error code is returned. Otherwise, 
+** SQLITE_OK.
+*/
+static int whereRangeSkipScanEst(
+  Parse *pParse,       /* Parsing & code generating context */
+  WhereTerm *pLower,   /* Lower bound on the range. ex: "x>123" Might be NULL */
+  WhereTerm *pUpper,   /* Upper bound on the range. ex: "x<455" Might be NULL */
+  WhereLoop *pLoop,    /* Update the .nOut value of this loop */
+  int *pbDone          /* Set to true if at least one expr. value extracted */
+){
+  Index *p = pLoop->u.btree.pIndex;
+  int nEq = pLoop->u.btree.nEq;
+  sqlite3 *db = pParse->db;
+  int nLower = -1;
+  int nUpper = p->nSample+1;
+  int rc = SQLITE_OK;
+  u8 aff = sqlite3IndexColumnAffinity(db, p, nEq);
+  CollSeq *pColl;
+  
+  sqlite3_value *p1 = 0;          /* Value extracted from pLower */
+  sqlite3_value *p2 = 0;          /* Value extracted from pUpper */
+  sqlite3_value *pVal = 0;        /* Value extracted from record */
+
+  pColl = sqlite3LocateCollSeq(pParse, p->azColl[nEq]);
+  if( pLower ){
+    rc = sqlite3Stat4ValueFromExpr(pParse, pLower->pExpr->pRight, aff, &p1);
+    nLower = 0;
+  }
+  if( pUpper && rc==SQLITE_OK ){
+    rc = sqlite3Stat4ValueFromExpr(pParse, pUpper->pExpr->pRight, aff, &p2);
+    nUpper = p2 ? 0 : p->nSample;
+  }
+
+  if( p1 || p2 ){
+    int i;
+    int nDiff;
+    for(i=0; rc==SQLITE_OK && i<p->nSample; i++){
+      rc = sqlite3Stat4Column(db, p->aSample[i].p, p->aSample[i].n, nEq, &pVal);
+      if( rc==SQLITE_OK && p1 ){
+        int res = sqlite3MemCompare(p1, pVal, pColl);
+        if( res>=0 ) nLower++;
+      }
+      if( rc==SQLITE_OK && p2 ){
+        int res = sqlite3MemCompare(p2, pVal, pColl);
+        if( res>=0 ) nUpper++;
+      }
+    }
+    nDiff = (nUpper - nLower);
+    if( nDiff<=0 ) nDiff = 1;
+
+    /* If there is both an upper and lower bound specified, and the 
+    ** comparisons indicate that they are close together, use the fallback
+    ** method (assume that the scan visits 1/64 of the rows) for estimating
+    ** the number of rows visited. Otherwise, estimate the number of rows
+    ** using the method described in the header comment for this function. */
+    if( nDiff!=1 || pUpper==0 || pLower==0 ){
+      int nAdjust = (sqlite3LogEst(p->nSample) - sqlite3LogEst(nDiff));
+      pLoop->nOut -= nAdjust;
+      *pbDone = 1;
+      WHERETRACE(0x10, ("range skip-scan regions: %u..%u  adjust=%d est=%d\n",
+                           nLower, nUpper, nAdjust*-1, pLoop->nOut));
+    }
+
+  }else{
+    assert( *pbDone==0 );
+  }
+
+  sqlite3ValueFree(p1);
+  sqlite3ValueFree(p2);
+  sqlite3ValueFree(pVal);
+
+  return rc;
+}
+#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
+
+/*
+** This function is used to estimate the number of rows that will be visited
+** by scanning an index for a range of values. The range may have an upper
+** bound, a lower bound, or both. The WHERE clause terms that set the upper
+** and lower bounds are represented by pLower and pUpper respectively. For
+** example, assuming that index p is on t1(a):
+**
+**   ... FROM t1 WHERE a > ? AND a < ? ...
+**                    |_____|   |_____|
+**                       |         |
+**                     pLower    pUpper
+**
+** If either of the upper or lower bound is not present, then NULL is passed in
+** place of the corresponding WhereTerm.
+**
+** The value in (pBuilder->pNew->u.btree.nEq) is the number of the index
+** column subject to the range constraint. Or, equivalently, the number of
+** equality constraints optimized by the proposed index scan. For example,
+** assuming index p is on t1(a, b), and the SQL query is:
+**
+**   ... FROM t1 WHERE a = ? AND b > ? AND b < ? ...
+**
+** then nEq is set to 1 (as the range restricted column, b, is the second 
+** left-most column of the index). Or, if the query is:
+**
+**   ... FROM t1 WHERE a > ? AND a < ? ...
+**
+** then nEq is set to 0.
+**
+** When this function is called, *pnOut is set to the sqlite3LogEst() of the
+** number of rows that the index scan is expected to visit without 
+** considering the range constraints. If nEq is 0, then *pnOut is the number of 
+** rows in the index. Assuming no error occurs, *pnOut is adjusted (reduced)
+** to account for the range constraints pLower and pUpper.
+** 
+** In the absence of sqlite_stat4 ANALYZE data, or if such data cannot be
+** used, a single range inequality reduces the search space by a factor of 4. 
+** and a pair of constraints (x>? AND x<?) reduces the expected number of
+** rows visited by a factor of 64.
+*/
+static int whereRangeScanEst(
+  Parse *pParse,       /* Parsing & code generating context */
+  WhereLoopBuilder *pBuilder,
+  WhereTerm *pLower,   /* Lower bound on the range. ex: "x>123" Might be NULL */
+  WhereTerm *pUpper,   /* Upper bound on the range. ex: "x<455" Might be NULL */
+  WhereLoop *pLoop     /* Modify the .nOut and maybe .rRun fields */
+){
+  int rc = SQLITE_OK;
+  int nOut = pLoop->nOut;
+  LogEst nNew;
+
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+  Index *p = pLoop->u.btree.pIndex;
+  int nEq = pLoop->u.btree.nEq;
+
+  if( p->nSample>0 && nEq<p->nSampleCol ){
+    if( nEq==pBuilder->nRecValid ){
+      UnpackedRecord *pRec = pBuilder->pRec;
+      tRowcnt a[2];
+      int nBtm = pLoop->u.btree.nBtm;
+      int nTop = pLoop->u.btree.nTop;
+
+      /* Variable iLower will be set to the estimate of the number of rows in 
+      ** the index that are less than the lower bound of the range query. The
+      ** lower bound being the concatenation of $P and $L, where $P is the
+      ** key-prefix formed by the nEq values matched against the nEq left-most
+      ** columns of the index, and $L is the value in pLower.
+      **
+      ** Or, if pLower is NULL or $L cannot be extracted from it (because it
+      ** is not a simple variable or literal value), the lower bound of the
+      ** range is $P. Due to a quirk in the way whereKeyStats() works, even
+      ** if $L is available, whereKeyStats() is called for both ($P) and 
+      ** ($P:$L) and the larger of the two returned values is used.
+      **
+      ** Similarly, iUpper is to be set to the estimate of the number of rows
+      ** less than the upper bound of the range query. Where the upper bound
+      ** is either ($P) or ($P:$U). Again, even if $U is available, both values
+      ** of iUpper are requested of whereKeyStats() and the smaller used.
+      **
+      ** The number of rows between the two bounds is then just iUpper-iLower.
+      */
+      tRowcnt iLower;     /* Rows less than the lower bound */
+      tRowcnt iUpper;     /* Rows less than the upper bound */
+      int iLwrIdx = -2;   /* aSample[] for the lower bound */
+      int iUprIdx = -1;   /* aSample[] for the upper bound */
+
+      if( pRec ){
+        testcase( pRec->nField!=pBuilder->nRecValid );
+        pRec->nField = pBuilder->nRecValid;
+      }
+      /* Determine iLower and iUpper using ($P) only. */
+      if( nEq==0 ){
+        iLower = 0;
+        iUpper = p->nRowEst0;
+      }else{
+        /* Note: this call could be optimized away - since the same values must 
+        ** have been requested when testing key $P in whereEqualScanEst().  */
+        whereKeyStats(pParse, p, pRec, 0, a);
+        iLower = a[0];
+        iUpper = a[0] + a[1];
+      }
+
+      assert( pLower==0 || (pLower->eOperator & (WO_GT|WO_GE))!=0 );
+      assert( pUpper==0 || (pUpper->eOperator & (WO_LT|WO_LE))!=0 );
+      assert( p->aSortOrder!=0 );
+      if( p->aSortOrder[nEq] ){
+        /* The roles of pLower and pUpper are swapped for a DESC index */
+        SWAP(WhereTerm*, pLower, pUpper);
+        SWAP(int, nBtm, nTop);
+      }
+
+      /* If possible, improve on the iLower estimate using ($P:$L). */
+      if( pLower ){
+        int n;                    /* Values extracted from pExpr */
+        Expr *pExpr = pLower->pExpr->pRight;
+        rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, nBtm, nEq, &n);
+        if( rc==SQLITE_OK && n ){
+          tRowcnt iNew;
+          u16 mask = WO_GT|WO_LE;
+          if( sqlite3ExprVectorSize(pExpr)>n ) mask = (WO_LE|WO_LT);
+          iLwrIdx = whereKeyStats(pParse, p, pRec, 0, a);
+          iNew = a[0] + ((pLower->eOperator & mask) ? a[1] : 0);
+          if( iNew>iLower ) iLower = iNew;
+          nOut--;
+          pLower = 0;
+        }
+      }
+
+      /* If possible, improve on the iUpper estimate using ($P:$U). */
+      if( pUpper ){
+        int n;                    /* Values extracted from pExpr */
+        Expr *pExpr = pUpper->pExpr->pRight;
+        rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, nTop, nEq, &n);
+        if( rc==SQLITE_OK && n ){
+          tRowcnt iNew;
+          u16 mask = WO_GT|WO_LE;
+          if( sqlite3ExprVectorSize(pExpr)>n ) mask = (WO_LE|WO_LT);
+          iUprIdx = whereKeyStats(pParse, p, pRec, 1, a);
+          iNew = a[0] + ((pUpper->eOperator & mask) ? a[1] : 0);
+          if( iNew<iUpper ) iUpper = iNew;
+          nOut--;
+          pUpper = 0;
+        }
+      }
+
+      pBuilder->pRec = pRec;
+      if( rc==SQLITE_OK ){
+        if( iUpper>iLower ){
+          nNew = sqlite3LogEst(iUpper - iLower);
+          /* TUNING:  If both iUpper and iLower are derived from the same
+          ** sample, then assume they are 4x more selective.  This brings
+          ** the estimated selectivity more in line with what it would be
+          ** if estimated without the use of STAT3/4 tables. */
+          if( iLwrIdx==iUprIdx ) nNew -= 20;  assert( 20==sqlite3LogEst(4) );
+        }else{
+          nNew = 10;        assert( 10==sqlite3LogEst(2) );
+        }
+        if( nNew<nOut ){
+          nOut = nNew;
+        }
+        WHERETRACE(0x10, ("STAT4 range scan: %u..%u  est=%d\n",
+                           (u32)iLower, (u32)iUpper, nOut));
+      }
+    }else{
+      int bDone = 0;
+      rc = whereRangeSkipScanEst(pParse, pLower, pUpper, pLoop, &bDone);
+      if( bDone ) return rc;
+    }
+  }
+#else
+  UNUSED_PARAMETER(pParse);
+  UNUSED_PARAMETER(pBuilder);
+  assert( pLower || pUpper );
+#endif
+  assert( pUpper==0 || (pUpper->wtFlags & TERM_VNULL)==0 );
+  nNew = whereRangeAdjust(pLower, nOut);
+  nNew = whereRangeAdjust(pUpper, nNew);
+
+  /* TUNING: If there is both an upper and lower limit and neither limit
+  ** has an application-defined likelihood(), assume the range is
+  ** reduced by an additional 75%. This means that, by default, an open-ended
+  ** range query (e.g. col > ?) is assumed to match 1/4 of the rows in the
+  ** index. While a closed range (e.g. col BETWEEN ? AND ?) is estimated to
+  ** match 1/64 of the index. */ 
+  if( pLower && pLower->truthProb>0 && pUpper && pUpper->truthProb>0 ){
+    nNew -= 20;
+  }
+
+  nOut -= (pLower!=0) + (pUpper!=0);
+  if( nNew<10 ) nNew = 10;
+  if( nNew<nOut ) nOut = nNew;
+#if defined(WHERETRACE_ENABLED)
+  if( pLoop->nOut>nOut ){
+    WHERETRACE(0x10,("Range scan lowers nOut from %d to %d\n",
+                    pLoop->nOut, nOut));
+  }
+#endif
+  pLoop->nOut = (LogEst)nOut;
+  return rc;
+}
+
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+/*
+** Estimate the number of rows that will be returned based on
+** an equality constraint x=VALUE and where that VALUE occurs in
+** the histogram data.  This only works when x is the left-most
+** column of an index and sqlite_stat3 histogram data is available
+** for that index.  When pExpr==NULL that means the constraint is
+** "x IS NULL" instead of "x=VALUE".
+**
+** Write the estimated row count into *pnRow and return SQLITE_OK. 
+** If unable to make an estimate, leave *pnRow unchanged and return
+** non-zero.
+**
+** This routine can fail if it is unable to load a collating sequence
+** required for string comparison, or if unable to allocate memory
+** for a UTF conversion required for comparison.  The error is stored
+** in the pParse structure.
+*/
+static int whereEqualScanEst(
+  Parse *pParse,       /* Parsing & code generating context */
+  WhereLoopBuilder *pBuilder,
+  Expr *pExpr,         /* Expression for VALUE in the x=VALUE constraint */
+  tRowcnt *pnRow       /* Write the revised row estimate here */
+){
+  Index *p = pBuilder->pNew->u.btree.pIndex;
+  int nEq = pBuilder->pNew->u.btree.nEq;
+  UnpackedRecord *pRec = pBuilder->pRec;
+  int rc;                   /* Subfunction return code */
+  tRowcnt a[2];             /* Statistics */
+  int bOk;
+
+  assert( nEq>=1 );
+  assert( nEq<=p->nColumn );
+  assert( p->aSample!=0 );
+  assert( p->nSample>0 );
+  assert( pBuilder->nRecValid<nEq );
+
+  /* If values are not available for all fields of the index to the left
+  ** of this one, no estimate can be made. Return SQLITE_NOTFOUND. */
+  if( pBuilder->nRecValid<(nEq-1) ){
+    return SQLITE_NOTFOUND;
+  }
+
+  /* This is an optimization only. The call to sqlite3Stat4ProbeSetValue()
+  ** below would return the same value.  */
+  if( nEq>=p->nColumn ){
+    *pnRow = 1;
+    return SQLITE_OK;
+  }
+
+  rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, 1, nEq-1, &bOk);
+  pBuilder->pRec = pRec;
+  if( rc!=SQLITE_OK ) return rc;
+  if( bOk==0 ) return SQLITE_NOTFOUND;
+  pBuilder->nRecValid = nEq;
+
+  whereKeyStats(pParse, p, pRec, 0, a);
+  WHERETRACE(0x10,("equality scan regions %s(%d): %d\n",
+                   p->zName, nEq-1, (int)a[1]));
+  *pnRow = a[1];
+  
+  return rc;
+}
+#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
+
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+/*
+** Estimate the number of rows that will be returned based on
+** an IN constraint where the right-hand side of the IN operator
+** is a list of values.  Example:
+**
+**        WHERE x IN (1,2,3,4)
+**
+** Write the estimated row count into *pnRow and return SQLITE_OK. 
+** If unable to make an estimate, leave *pnRow unchanged and return
+** non-zero.
+**
+** This routine can fail if it is unable to load a collating sequence
+** required for string comparison, or if unable to allocate memory
+** for a UTF conversion required for comparison.  The error is stored
+** in the pParse structure.
+*/
+static int whereInScanEst(
+  Parse *pParse,       /* Parsing & code generating context */
+  WhereLoopBuilder *pBuilder,
+  ExprList *pList,     /* The value list on the RHS of "x IN (v1,v2,v3,...)" */
+  tRowcnt *pnRow       /* Write the revised row estimate here */
+){
+  Index *p = pBuilder->pNew->u.btree.pIndex;
+  i64 nRow0 = sqlite3LogEstToInt(p->aiRowLogEst[0]);
+  int nRecValid = pBuilder->nRecValid;
+  int rc = SQLITE_OK;     /* Subfunction return code */
+  tRowcnt nEst;           /* Number of rows for a single term */
+  tRowcnt nRowEst = 0;    /* New estimate of the number of rows */
+  int i;                  /* Loop counter */
+
+  assert( p->aSample!=0 );
+  for(i=0; rc==SQLITE_OK && i<pList->nExpr; i++){
+    nEst = nRow0;
+    rc = whereEqualScanEst(pParse, pBuilder, pList->a[i].pExpr, &nEst);
+    nRowEst += nEst;
+    pBuilder->nRecValid = nRecValid;
+  }
+
+  if( rc==SQLITE_OK ){
+    if( nRowEst > nRow0 ) nRowEst = nRow0;
+    *pnRow = nRowEst;
+    WHERETRACE(0x10,("IN row estimate: est=%d\n", nRowEst));
+  }
+  assert( pBuilder->nRecValid==nRecValid );
+  return rc;
+}
+#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
+
+
+#ifdef WHERETRACE_ENABLED
+/*
+** Print the content of a WhereTerm object
+*/
+static void whereTermPrint(WhereTerm *pTerm, int iTerm){
+  if( pTerm==0 ){
+    sqlite3DebugPrintf("TERM-%-3d NULL\n", iTerm);
+  }else{
+    char zType[4];
+    char zLeft[50];
+    memcpy(zType, "...", 4);
+    if( pTerm->wtFlags & TERM_VIRTUAL ) zType[0] = 'V';
+    if( pTerm->eOperator & WO_EQUIV  ) zType[1] = 'E';
+    if( ExprHasProperty(pTerm->pExpr, EP_FromJoin) ) zType[2] = 'L';
+    if( pTerm->eOperator & WO_SINGLE ){
+      sqlite3_snprintf(sizeof(zLeft),zLeft,"left={%d:%d}",
+                       pTerm->leftCursor, pTerm->u.leftColumn);
+    }else if( (pTerm->eOperator & WO_OR)!=0 && pTerm->u.pOrInfo!=0 ){
+      sqlite3_snprintf(sizeof(zLeft),zLeft,"indexable=0x%lld", 
+                       pTerm->u.pOrInfo->indexable);
+    }else{
+      sqlite3_snprintf(sizeof(zLeft),zLeft,"left=%d", pTerm->leftCursor);
+    }
+    sqlite3DebugPrintf(
+       "TERM-%-3d %p %s %-12s prob=%-3d op=0x%03x wtFlags=0x%04x",
+       iTerm, pTerm, zType, zLeft, pTerm->truthProb,
+       pTerm->eOperator, pTerm->wtFlags);
+    if( pTerm->iField ){
+      sqlite3DebugPrintf(" iField=%d\n", pTerm->iField);
+    }else{
+      sqlite3DebugPrintf("\n");
+    }
+    sqlite3TreeViewExpr(0, pTerm->pExpr, 0);
+  }
+}
+#endif
+
+#ifdef WHERETRACE_ENABLED
+/*
+** Show the complete content of a WhereClause
+*/
+SQLITE_PRIVATE void sqlite3WhereClausePrint(WhereClause *pWC){
+  int i;
+  for(i=0; i<pWC->nTerm; i++){
+    whereTermPrint(&pWC->a[i], i);
+  }
+}
+#endif
+
+#ifdef WHERETRACE_ENABLED
+/*
+** Print a WhereLoop object for debugging purposes
+*/
+static void whereLoopPrint(WhereLoop *p, WhereClause *pWC){
+  WhereInfo *pWInfo = pWC->pWInfo;
+  int nb = 1+(pWInfo->pTabList->nSrc+3)/4;
+  struct SrcList_item *pItem = pWInfo->pTabList->a + p->iTab;
+  Table *pTab = pItem->pTab;
+  Bitmask mAll = (((Bitmask)1)<<(nb*4)) - 1;
+  sqlite3DebugPrintf("%c%2d.%0*llx.%0*llx", p->cId,
+                     p->iTab, nb, p->maskSelf, nb, p->prereq & mAll);
+  sqlite3DebugPrintf(" %12s",
+                     pItem->zAlias ? pItem->zAlias : pTab->zName);
+  if( (p->wsFlags & WHERE_VIRTUALTABLE)==0 ){
+    const char *zName;
+    if( p->u.btree.pIndex && (zName = p->u.btree.pIndex->zName)!=0 ){
+      if( strncmp(zName, "sqlite_autoindex_", 17)==0 ){
+        int i = sqlite3Strlen30(zName) - 1;
+        while( zName[i]!='_' ) i--;
+        zName += i;
+      }
+      sqlite3DebugPrintf(".%-16s %2d", zName, p->u.btree.nEq);
+    }else{
+      sqlite3DebugPrintf("%20s","");
+    }
+  }else{
+    char *z;
+    if( p->u.vtab.idxStr ){
+      z = sqlite3_mprintf("(%d,\"%s\",%x)",
+                p->u.vtab.idxNum, p->u.vtab.idxStr, p->u.vtab.omitMask);
+    }else{
+      z = sqlite3_mprintf("(%d,%x)", p->u.vtab.idxNum, p->u.vtab.omitMask);
+    }
+    sqlite3DebugPrintf(" %-19s", z);
+    sqlite3_free(z);
+  }
+  if( p->wsFlags & WHERE_SKIPSCAN ){
+    sqlite3DebugPrintf(" f %05x %d-%d", p->wsFlags, p->nLTerm,p->nSkip);
+  }else{
+    sqlite3DebugPrintf(" f %05x N %d", p->wsFlags, p->nLTerm);
+  }
+  sqlite3DebugPrintf(" cost %d,%d,%d\n", p->rSetup, p->rRun, p->nOut);
+  if( p->nLTerm && (sqlite3WhereTrace & 0x100)!=0 ){
+    int i;
+    for(i=0; i<p->nLTerm; i++){
+      whereTermPrint(p->aLTerm[i], i);
+    }
+  }
+}
+#endif
+
+/*
+** Convert bulk memory into a valid WhereLoop that can be passed
+** to whereLoopClear harmlessly.
+*/
+static void whereLoopInit(WhereLoop *p){
+  p->aLTerm = p->aLTermSpace;
+  p->nLTerm = 0;
+  p->nLSlot = ArraySize(p->aLTermSpace);
+  p->wsFlags = 0;
+}
+
+/*
+** Clear the WhereLoop.u union.  Leave WhereLoop.pLTerm intact.
+*/
+static void whereLoopClearUnion(sqlite3 *db, WhereLoop *p){
+  if( p->wsFlags & (WHERE_VIRTUALTABLE|WHERE_AUTO_INDEX) ){
+    if( (p->wsFlags & WHERE_VIRTUALTABLE)!=0 && p->u.vtab.needFree ){
+      sqlite3_free(p->u.vtab.idxStr);
+      p->u.vtab.needFree = 0;
+      p->u.vtab.idxStr = 0;
+    }else if( (p->wsFlags & WHERE_AUTO_INDEX)!=0 && p->u.btree.pIndex!=0 ){
+      sqlite3DbFree(db, p->u.btree.pIndex->zColAff);
+      sqlite3DbFree(db, p->u.btree.pIndex);
+      p->u.btree.pIndex = 0;
+    }
+  }
+}
+
+/*
+** Deallocate internal memory used by a WhereLoop object
+*/
+static void whereLoopClear(sqlite3 *db, WhereLoop *p){
+  if( p->aLTerm!=p->aLTermSpace ) sqlite3DbFree(db, p->aLTerm);
+  whereLoopClearUnion(db, p);
+  whereLoopInit(p);
+}
+
+/*
+** Increase the memory allocation for pLoop->aLTerm[] to be at least n.
+*/
+static int whereLoopResize(sqlite3 *db, WhereLoop *p, int n){
+  WhereTerm **paNew;
+  if( p->nLSlot>=n ) return SQLITE_OK;
+  n = (n+7)&~7;
+  paNew = sqlite3DbMallocRawNN(db, sizeof(p->aLTerm[0])*n);
+  if( paNew==0 ) return SQLITE_NOMEM_BKPT;
+  memcpy(paNew, p->aLTerm, sizeof(p->aLTerm[0])*p->nLSlot);
+  if( p->aLTerm!=p->aLTermSpace ) sqlite3DbFree(db, p->aLTerm);
+  p->aLTerm = paNew;
+  p->nLSlot = n;
+  return SQLITE_OK;
+}
+
+/*
+** Transfer content from the second pLoop into the first.
+*/
+static int whereLoopXfer(sqlite3 *db, WhereLoop *pTo, WhereLoop *pFrom){
+  whereLoopClearUnion(db, pTo);
+  if( whereLoopResize(db, pTo, pFrom->nLTerm) ){
+    memset(&pTo->u, 0, sizeof(pTo->u));
+    return SQLITE_NOMEM_BKPT;
+  }
+  memcpy(pTo, pFrom, WHERE_LOOP_XFER_SZ);
+  memcpy(pTo->aLTerm, pFrom->aLTerm, pTo->nLTerm*sizeof(pTo->aLTerm[0]));
+  if( pFrom->wsFlags & WHERE_VIRTUALTABLE ){
+    pFrom->u.vtab.needFree = 0;
+  }else if( (pFrom->wsFlags & WHERE_AUTO_INDEX)!=0 ){
+    pFrom->u.btree.pIndex = 0;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Delete a WhereLoop object
+*/
+static void whereLoopDelete(sqlite3 *db, WhereLoop *p){
+  whereLoopClear(db, p);
+  sqlite3DbFree(db, p);
+}
+
+/*
+** Free a WhereInfo structure
+*/
+static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){
+  if( ALWAYS(pWInfo) ){
+    int i;
+    for(i=0; i<pWInfo->nLevel; i++){
+      WhereLevel *pLevel = &pWInfo->a[i];
+      if( pLevel->pWLoop && (pLevel->pWLoop->wsFlags & WHERE_IN_ABLE) ){
+        sqlite3DbFree(db, pLevel->u.in.aInLoop);
+      }
+    }
+    sqlite3WhereClauseClear(&pWInfo->sWC);
+    while( pWInfo->pLoops ){
+      WhereLoop *p = pWInfo->pLoops;
+      pWInfo->pLoops = p->pNextLoop;
+      whereLoopDelete(db, p);
+    }
+    sqlite3DbFree(db, pWInfo);
+  }
+}
+
+/*
+** Return TRUE if all of the following are true:
+**
+**   (1)  X has the same or lower cost that Y
+**   (2)  X is a proper subset of Y
+**   (3)  X skips at least as many columns as Y
+**
+** By "proper subset" we mean that X uses fewer WHERE clause terms
+** than Y and that every WHERE clause term used by X is also used
+** by Y.
+**
+** If X is a proper subset of Y then Y is a better choice and ought
+** to have a lower cost.  This routine returns TRUE when that cost 
+** relationship is inverted and needs to be adjusted.  The third rule
+** was added because if X uses skip-scan less than Y it still might
+** deserve a lower cost even if it is a proper subset of Y.
+*/
+static int whereLoopCheaperProperSubset(
+  const WhereLoop *pX,       /* First WhereLoop to compare */
+  const WhereLoop *pY        /* Compare against this WhereLoop */
+){
+  int i, j;
+  if( pX->nLTerm-pX->nSkip >= pY->nLTerm-pY->nSkip ){
+    return 0; /* X is not a subset of Y */
+  }
+  if( pY->nSkip > pX->nSkip ) return 0;
+  if( pX->rRun >= pY->rRun ){
+    if( pX->rRun > pY->rRun ) return 0;    /* X costs more than Y */
+    if( pX->nOut > pY->nOut ) return 0;    /* X costs more than Y */
+  }
+  for(i=pX->nLTerm-1; i>=0; i--){
+    if( pX->aLTerm[i]==0 ) continue;
+    for(j=pY->nLTerm-1; j>=0; j--){
+      if( pY->aLTerm[j]==pX->aLTerm[i] ) break;
+    }
+    if( j<0 ) return 0;  /* X not a subset of Y since term X[i] not used by Y */
+  }
+  return 1;  /* All conditions meet */
+}
+
+/*
+** Try to adjust the cost of WhereLoop pTemplate upwards or downwards so
+** that:
+**
+**   (1) pTemplate costs less than any other WhereLoops that are a proper
+**       subset of pTemplate
+**
+**   (2) pTemplate costs more than any other WhereLoops for which pTemplate
+**       is a proper subset.
+**
+** To say "WhereLoop X is a proper subset of Y" means that X uses fewer
+** WHERE clause terms than Y and that every WHERE clause term used by X is
+** also used by Y.
+*/
+static void whereLoopAdjustCost(const WhereLoop *p, WhereLoop *pTemplate){
+  if( (pTemplate->wsFlags & WHERE_INDEXED)==0 ) return;
+  for(; p; p=p->pNextLoop){
+    if( p->iTab!=pTemplate->iTab ) continue;
+    if( (p->wsFlags & WHERE_INDEXED)==0 ) continue;
+    if( whereLoopCheaperProperSubset(p, pTemplate) ){
+      /* Adjust pTemplate cost downward so that it is cheaper than its 
+      ** subset p. */
+      WHERETRACE(0x80,("subset cost adjustment %d,%d to %d,%d\n",
+                       pTemplate->rRun, pTemplate->nOut, p->rRun, p->nOut-1));
+      pTemplate->rRun = p->rRun;
+      pTemplate->nOut = p->nOut - 1;
+    }else if( whereLoopCheaperProperSubset(pTemplate, p) ){
+      /* Adjust pTemplate cost upward so that it is costlier than p since
+      ** pTemplate is a proper subset of p */
+      WHERETRACE(0x80,("subset cost adjustment %d,%d to %d,%d\n",
+                       pTemplate->rRun, pTemplate->nOut, p->rRun, p->nOut+1));
+      pTemplate->rRun = p->rRun;
+      pTemplate->nOut = p->nOut + 1;
+    }
+  }
+}
+
+/*
+** Search the list of WhereLoops in *ppPrev looking for one that can be
+** supplanted by pTemplate.
+**
+** Return NULL if the WhereLoop list contains an entry that can supplant
+** pTemplate, in other words if pTemplate does not belong on the list.
+**
+** If pX is a WhereLoop that pTemplate can supplant, then return the
+** link that points to pX.
+**
+** If pTemplate cannot supplant any existing element of the list but needs
+** to be added to the list, then return a pointer to the tail of the list.
+*/
+static WhereLoop **whereLoopFindLesser(
+  WhereLoop **ppPrev,
+  const WhereLoop *pTemplate
+){
+  WhereLoop *p;
+  for(p=(*ppPrev); p; ppPrev=&p->pNextLoop, p=*ppPrev){
+    if( p->iTab!=pTemplate->iTab || p->iSortIdx!=pTemplate->iSortIdx ){
+      /* If either the iTab or iSortIdx values for two WhereLoop are different
+      ** then those WhereLoops need to be considered separately.  Neither is
+      ** a candidate to replace the other. */
+      continue;
+    }
+    /* In the current implementation, the rSetup value is either zero
+    ** or the cost of building an automatic index (NlogN) and the NlogN
+    ** is the same for compatible WhereLoops. */
+    assert( p->rSetup==0 || pTemplate->rSetup==0 
+                 || p->rSetup==pTemplate->rSetup );
+
+    /* whereLoopAddBtree() always generates and inserts the automatic index
+    ** case first.  Hence compatible candidate WhereLoops never have a larger
+    ** rSetup. Call this SETUP-INVARIANT */
+    assert( p->rSetup>=pTemplate->rSetup );
+
+    /* Any loop using an appliation-defined index (or PRIMARY KEY or
+    ** UNIQUE constraint) with one or more == constraints is better
+    ** than an automatic index. Unless it is a skip-scan. */
+    if( (p->wsFlags & WHERE_AUTO_INDEX)!=0
+     && (pTemplate->nSkip)==0
+     && (pTemplate->wsFlags & WHERE_INDEXED)!=0
+     && (pTemplate->wsFlags & WHERE_COLUMN_EQ)!=0
+     && (p->prereq & pTemplate->prereq)==pTemplate->prereq
+    ){
+      break;
+    }
+
+    /* If existing WhereLoop p is better than pTemplate, pTemplate can be
+    ** discarded.  WhereLoop p is better if:
+    **   (1)  p has no more dependencies than pTemplate, and
+    **   (2)  p has an equal or lower cost than pTemplate
+    */
+    if( (p->prereq & pTemplate->prereq)==p->prereq    /* (1)  */
+     && p->rSetup<=pTemplate->rSetup                  /* (2a) */
+     && p->rRun<=pTemplate->rRun                      /* (2b) */
+     && p->nOut<=pTemplate->nOut                      /* (2c) */
+    ){
+      return 0;  /* Discard pTemplate */
+    }
+
+    /* If pTemplate is always better than p, then cause p to be overwritten
+    ** with pTemplate.  pTemplate is better than p if:
+    **   (1)  pTemplate has no more dependences than p, and
+    **   (2)  pTemplate has an equal or lower cost than p.
+    */
+    if( (p->prereq & pTemplate->prereq)==pTemplate->prereq   /* (1)  */
+     && p->rRun>=pTemplate->rRun                             /* (2a) */
+     && p->nOut>=pTemplate->nOut                             /* (2b) */
+    ){
+      assert( p->rSetup>=pTemplate->rSetup ); /* SETUP-INVARIANT above */
+      break;   /* Cause p to be overwritten by pTemplate */
+    }
+  }
+  return ppPrev;
+}
+
+/*
+** Insert or replace a WhereLoop entry using the template supplied.
+**
+** An existing WhereLoop entry might be overwritten if the new template
+** is better and has fewer dependencies.  Or the template will be ignored
+** and no insert will occur if an existing WhereLoop is faster and has
+** fewer dependencies than the template.  Otherwise a new WhereLoop is
+** added based on the template.
+**
+** If pBuilder->pOrSet is not NULL then we care about only the
+** prerequisites and rRun and nOut costs of the N best loops.  That
+** information is gathered in the pBuilder->pOrSet object.  This special
+** processing mode is used only for OR clause processing.
+**
+** When accumulating multiple loops (when pBuilder->pOrSet is NULL) we
+** still might overwrite similar loops with the new template if the
+** new template is better.  Loops may be overwritten if the following 
+** conditions are met:
+**
+**    (1)  They have the same iTab.
+**    (2)  They have the same iSortIdx.
+**    (3)  The template has same or fewer dependencies than the current loop
+**    (4)  The template has the same or lower cost than the current loop
+*/
+static int whereLoopInsert(WhereLoopBuilder *pBuilder, WhereLoop *pTemplate){
+  WhereLoop **ppPrev, *p;
+  WhereInfo *pWInfo = pBuilder->pWInfo;
+  sqlite3 *db = pWInfo->pParse->db;
+  int rc;
+
+  /* If pBuilder->pOrSet is defined, then only keep track of the costs
+  ** and prereqs.
+  */
+  if( pBuilder->pOrSet!=0 ){
+    if( pTemplate->nLTerm ){
+#if WHERETRACE_ENABLED
+      u16 n = pBuilder->pOrSet->n;
+      int x =
+#endif
+      whereOrInsert(pBuilder->pOrSet, pTemplate->prereq, pTemplate->rRun,
+                                    pTemplate->nOut);
+#if WHERETRACE_ENABLED /* 0x8 */
+      if( sqlite3WhereTrace & 0x8 ){
+        sqlite3DebugPrintf(x?"   or-%d:  ":"   or-X:  ", n);
+        whereLoopPrint(pTemplate, pBuilder->pWC);
+      }
+#endif
+    }
+    return SQLITE_OK;
+  }
+
+  /* Look for an existing WhereLoop to replace with pTemplate
+  */
+  whereLoopAdjustCost(pWInfo->pLoops, pTemplate);
+  ppPrev = whereLoopFindLesser(&pWInfo->pLoops, pTemplate);
+
+  if( ppPrev==0 ){
+    /* There already exists a WhereLoop on the list that is better
+    ** than pTemplate, so just ignore pTemplate */
+#if WHERETRACE_ENABLED /* 0x8 */
+    if( sqlite3WhereTrace & 0x8 ){
+      sqlite3DebugPrintf("   skip: ");
+      whereLoopPrint(pTemplate, pBuilder->pWC);
+    }
+#endif
+    return SQLITE_OK;  
+  }else{
+    p = *ppPrev;
+  }
+
+  /* If we reach this point it means that either p[] should be overwritten
+  ** with pTemplate[] if p[] exists, or if p==NULL then allocate a new
+  ** WhereLoop and insert it.
+  */
+#if WHERETRACE_ENABLED /* 0x8 */
+  if( sqlite3WhereTrace & 0x8 ){
+    if( p!=0 ){
+      sqlite3DebugPrintf("replace: ");
+      whereLoopPrint(p, pBuilder->pWC);
+    }
+    sqlite3DebugPrintf("    add: ");
+    whereLoopPrint(pTemplate, pBuilder->pWC);
+  }
+#endif
+  if( p==0 ){
+    /* Allocate a new WhereLoop to add to the end of the list */
+    *ppPrev = p = sqlite3DbMallocRawNN(db, sizeof(WhereLoop));
+    if( p==0 ) return SQLITE_NOMEM_BKPT;
+    whereLoopInit(p);
+    p->pNextLoop = 0;
+  }else{
+    /* We will be overwriting WhereLoop p[].  But before we do, first
+    ** go through the rest of the list and delete any other entries besides
+    ** p[] that are also supplated by pTemplate */
+    WhereLoop **ppTail = &p->pNextLoop;
+    WhereLoop *pToDel;
+    while( *ppTail ){
+      ppTail = whereLoopFindLesser(ppTail, pTemplate);
+      if( ppTail==0 ) break;
+      pToDel = *ppTail;
+      if( pToDel==0 ) break;
+      *ppTail = pToDel->pNextLoop;
+#if WHERETRACE_ENABLED /* 0x8 */
+      if( sqlite3WhereTrace & 0x8 ){
+        sqlite3DebugPrintf(" delete: ");
+        whereLoopPrint(pToDel, pBuilder->pWC);
+      }
+#endif
+      whereLoopDelete(db, pToDel);
+    }
+  }
+  rc = whereLoopXfer(db, p, pTemplate);
+  if( (p->wsFlags & WHERE_VIRTUALTABLE)==0 ){
+    Index *pIndex = p->u.btree.pIndex;
+    if( pIndex && pIndex->tnum==0 ){
+      p->u.btree.pIndex = 0;
+    }
+  }
+  return rc;
+}
+
+/*
+** Adjust the WhereLoop.nOut value downward to account for terms of the
+** WHERE clause that reference the loop but which are not used by an
+** index.
+*
+** For every WHERE clause term that is not used by the index
+** and which has a truth probability assigned by one of the likelihood(),
+** likely(), or unlikely() SQL functions, reduce the estimated number
+** of output rows by the probability specified.
+**
+** TUNING:  For every WHERE clause term that is not used by the index
+** and which does not have an assigned truth probability, heuristics
+** described below are used to try to estimate the truth probability.
+** TODO --> Perhaps this is something that could be improved by better
+** table statistics.
+**
+** Heuristic 1:  Estimate the truth probability as 93.75%.  The 93.75%
+** value corresponds to -1 in LogEst notation, so this means decrement
+** the WhereLoop.nOut field for every such WHERE clause term.
+**
+** Heuristic 2:  If there exists one or more WHERE clause terms of the
+** form "x==EXPR" and EXPR is not a constant 0 or 1, then make sure the
+** final output row estimate is no greater than 1/4 of the total number
+** of rows in the table.  In other words, assume that x==EXPR will filter
+** out at least 3 out of 4 rows.  If EXPR is -1 or 0 or 1, then maybe the
+** "x" column is boolean or else -1 or 0 or 1 is a common default value
+** on the "x" column and so in that case only cap the output row estimate
+** at 1/2 instead of 1/4.
+*/
+static void whereLoopOutputAdjust(
+  WhereClause *pWC,      /* The WHERE clause */
+  WhereLoop *pLoop,      /* The loop to adjust downward */
+  LogEst nRow            /* Number of rows in the entire table */
+){
+  WhereTerm *pTerm, *pX;
+  Bitmask notAllowed = ~(pLoop->prereq|pLoop->maskSelf);
+  int i, j, k;
+  LogEst iReduce = 0;    /* pLoop->nOut should not exceed nRow-iReduce */
+
+  assert( (pLoop->wsFlags & WHERE_AUTO_INDEX)==0 );
+  for(i=pWC->nTerm, pTerm=pWC->a; i>0; i--, pTerm++){
+    if( (pTerm->wtFlags & TERM_VIRTUAL)!=0 ) break;
+    if( (pTerm->prereqAll & pLoop->maskSelf)==0 ) continue;
+    if( (pTerm->prereqAll & notAllowed)!=0 ) continue;
+    for(j=pLoop->nLTerm-1; j>=0; j--){
+      pX = pLoop->aLTerm[j];
+      if( pX==0 ) continue;
+      if( pX==pTerm ) break;
+      if( pX->iParent>=0 && (&pWC->a[pX->iParent])==pTerm ) break;
+    }
+    if( j<0 ){
+      if( pTerm->truthProb<=0 ){
+        /* If a truth probability is specified using the likelihood() hints,
+        ** then use the probability provided by the application. */
+        pLoop->nOut += pTerm->truthProb;
+      }else{
+        /* In the absence of explicit truth probabilities, use heuristics to
+        ** guess a reasonable truth probability. */
+        pLoop->nOut--;
+        if( pTerm->eOperator&(WO_EQ|WO_IS) ){
+          Expr *pRight = pTerm->pExpr->pRight;
+          testcase( pTerm->pExpr->op==TK_IS );
+          if( sqlite3ExprIsInteger(pRight, &k) && k>=(-1) && k<=1 ){
+            k = 10;
+          }else{
+            k = 20;
+          }
+          if( iReduce<k ) iReduce = k;
+        }
+      }
+    }
+  }
+  if( pLoop->nOut > nRow-iReduce )  pLoop->nOut = nRow - iReduce;
+}
+
+/* 
+** Term pTerm is a vector range comparison operation. The first comparison
+** in the vector can be optimized using column nEq of the index. This
+** function returns the total number of vector elements that can be used
+** as part of the range comparison.
+**
+** For example, if the query is:
+**
+**   WHERE a = ? AND (b, c, d) > (?, ?, ?)
+**
+** and the index:
+**
+**   CREATE INDEX ... ON (a, b, c, d, e)
+**
+** then this function would be invoked with nEq=1. The value returned in
+** this case is 3.
+*/
+static int whereRangeVectorLen(
+  Parse *pParse,       /* Parsing context */
+  int iCur,            /* Cursor open on pIdx */
+  Index *pIdx,         /* The index to be used for a inequality constraint */
+  int nEq,             /* Number of prior equality constraints on same index */
+  WhereTerm *pTerm     /* The vector inequality constraint */
+){
+  int nCmp = sqlite3ExprVectorSize(pTerm->pExpr->pLeft);
+  int i;
+
+  nCmp = MIN(nCmp, (pIdx->nColumn - nEq));
+  for(i=1; i<nCmp; i++){
+    /* Test if comparison i of pTerm is compatible with column (i+nEq) 
+    ** of the index. If not, exit the loop.  */
+    char aff;                     /* Comparison affinity */
+    char idxaff = 0;              /* Indexed columns affinity */
+    CollSeq *pColl;               /* Comparison collation sequence */
+    Expr *pLhs = pTerm->pExpr->pLeft->x.pList->a[i].pExpr;
+    Expr *pRhs = pTerm->pExpr->pRight;
+    if( pRhs->flags & EP_xIsSelect ){
+      pRhs = pRhs->x.pSelect->pEList->a[i].pExpr;
+    }else{
+      pRhs = pRhs->x.pList->a[i].pExpr;
+    }
+
+    /* Check that the LHS of the comparison is a column reference to
+    ** the right column of the right source table. And that the sort
+    ** order of the index column is the same as the sort order of the
+    ** leftmost index column.  */
+    if( pLhs->op!=TK_COLUMN 
+     || pLhs->iTable!=iCur 
+     || pLhs->iColumn!=pIdx->aiColumn[i+nEq] 
+     || pIdx->aSortOrder[i+nEq]!=pIdx->aSortOrder[nEq]
+    ){
+      break;
+    }
+
+    testcase( pLhs->iColumn==XN_ROWID );
+    aff = sqlite3CompareAffinity(pRhs, sqlite3ExprAffinity(pLhs));
+    idxaff = sqlite3TableColumnAffinity(pIdx->pTable, pLhs->iColumn);
+    if( aff!=idxaff ) break;
+
+    pColl = sqlite3BinaryCompareCollSeq(pParse, pLhs, pRhs);
+    if( pColl==0 ) break;
+    if( sqlite3StrICmp(pColl->zName, pIdx->azColl[i+nEq]) ) break;
+  }
+  return i;
+}
+
+/*
+** Adjust the cost C by the costMult facter T.  This only occurs if
+** compiled with -DSQLITE_ENABLE_COSTMULT
+*/
+#ifdef SQLITE_ENABLE_COSTMULT
+# define ApplyCostMultiplier(C,T)  C += T
+#else
+# define ApplyCostMultiplier(C,T)
+#endif
+
+/*
+** We have so far matched pBuilder->pNew->u.btree.nEq terms of the 
+** index pIndex. Try to match one more.
+**
+** When this function is called, pBuilder->pNew->nOut contains the 
+** number of rows expected to be visited by filtering using the nEq 
+** terms only. If it is modified, this value is restored before this 
+** function returns.
+**
+** If pProbe->tnum==0, that means pIndex is a fake index used for the
+** INTEGER PRIMARY KEY.
+*/
+static int whereLoopAddBtreeIndex(
+  WhereLoopBuilder *pBuilder,     /* The WhereLoop factory */
+  struct SrcList_item *pSrc,      /* FROM clause term being analyzed */
+  Index *pProbe,                  /* An index on pSrc */
+  LogEst nInMul                   /* log(Number of iterations due to IN) */
+){
+  WhereInfo *pWInfo = pBuilder->pWInfo;  /* WHERE analyse context */
+  Parse *pParse = pWInfo->pParse;        /* Parsing context */
+  sqlite3 *db = pParse->db;       /* Database connection malloc context */
+  WhereLoop *pNew;                /* Template WhereLoop under construction */
+  WhereTerm *pTerm;               /* A WhereTerm under consideration */
+  int opMask;                     /* Valid operators for constraints */
+  WhereScan scan;                 /* Iterator for WHERE terms */
+  Bitmask saved_prereq;           /* Original value of pNew->prereq */
+  u16 saved_nLTerm;               /* Original value of pNew->nLTerm */
+  u16 saved_nEq;                  /* Original value of pNew->u.btree.nEq */
+  u16 saved_nBtm;                 /* Original value of pNew->u.btree.nBtm */
+  u16 saved_nTop;                 /* Original value of pNew->u.btree.nTop */
+  u16 saved_nSkip;                /* Original value of pNew->nSkip */
+  u32 saved_wsFlags;              /* Original value of pNew->wsFlags */
+  LogEst saved_nOut;              /* Original value of pNew->nOut */
+  int rc = SQLITE_OK;             /* Return code */
+  LogEst rSize;                   /* Number of rows in the table */
+  LogEst rLogSize;                /* Logarithm of table size */
+  WhereTerm *pTop = 0, *pBtm = 0; /* Top and bottom range constraints */
+
+  pNew = pBuilder->pNew;
+  if( db->mallocFailed ) return SQLITE_NOMEM_BKPT;
+  WHERETRACE(0x800, ("BEGIN addBtreeIdx(%s), nEq=%d\n",
+                     pProbe->zName, pNew->u.btree.nEq));
+
+  assert( (pNew->wsFlags & WHERE_VIRTUALTABLE)==0 );
+  assert( (pNew->wsFlags & WHERE_TOP_LIMIT)==0 );
+  if( pNew->wsFlags & WHERE_BTM_LIMIT ){
+    opMask = WO_LT|WO_LE;
+  }else{
+    assert( pNew->u.btree.nBtm==0 );
+    opMask = WO_EQ|WO_IN|WO_GT|WO_GE|WO_LT|WO_LE|WO_ISNULL|WO_IS;
+  }
+  if( pProbe->bUnordered ) opMask &= ~(WO_GT|WO_GE|WO_LT|WO_LE);
+
+  assert( pNew->u.btree.nEq<pProbe->nColumn );
+
+  saved_nEq = pNew->u.btree.nEq;
+  saved_nBtm = pNew->u.btree.nBtm;
+  saved_nTop = pNew->u.btree.nTop;
+  saved_nSkip = pNew->nSkip;
+  saved_nLTerm = pNew->nLTerm;
+  saved_wsFlags = pNew->wsFlags;
+  saved_prereq = pNew->prereq;
+  saved_nOut = pNew->nOut;
+  pTerm = whereScanInit(&scan, pBuilder->pWC, pSrc->iCursor, saved_nEq,
+                        opMask, pProbe);
+  pNew->rSetup = 0;
+  rSize = pProbe->aiRowLogEst[0];
+  rLogSize = estLog(rSize);
+  for(; rc==SQLITE_OK && pTerm!=0; pTerm = whereScanNext(&scan)){
+    u16 eOp = pTerm->eOperator;   /* Shorthand for pTerm->eOperator */
+    LogEst rCostIdx;
+    LogEst nOutUnadjusted;        /* nOut before IN() and WHERE adjustments */
+    int nIn = 0;
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+    int nRecValid = pBuilder->nRecValid;
+#endif
+    if( (eOp==WO_ISNULL || (pTerm->wtFlags&TERM_VNULL)!=0)
+     && indexColumnNotNull(pProbe, saved_nEq)
+    ){
+      continue; /* ignore IS [NOT] NULL constraints on NOT NULL columns */
+    }
+    if( pTerm->prereqRight & pNew->maskSelf ) continue;
+
+    /* Do not allow the upper bound of a LIKE optimization range constraint
+    ** to mix with a lower range bound from some other source */
+    if( pTerm->wtFlags & TERM_LIKEOPT && pTerm->eOperator==WO_LT ) continue;
+
+    /* Do not allow IS constraints from the WHERE clause to be used by the
+    ** right table of a LEFT JOIN.  Only constraints in the ON clause are
+    ** allowed */
+    if( (pSrc->fg.jointype & JT_LEFT)!=0
+     && !ExprHasProperty(pTerm->pExpr, EP_FromJoin)
+     && (eOp & (WO_IS|WO_ISNULL))!=0
+    ){
+      testcase( eOp & WO_IS );
+      testcase( eOp & WO_ISNULL );
+      continue;
+    }
+
+    pNew->wsFlags = saved_wsFlags;
+    pNew->u.btree.nEq = saved_nEq;
+    pNew->u.btree.nBtm = saved_nBtm;
+    pNew->u.btree.nTop = saved_nTop;
+    pNew->nLTerm = saved_nLTerm;
+    if( whereLoopResize(db, pNew, pNew->nLTerm+1) ) break; /* OOM */
+    pNew->aLTerm[pNew->nLTerm++] = pTerm;
+    pNew->prereq = (saved_prereq | pTerm->prereqRight) & ~pNew->maskSelf;
+
+    assert( nInMul==0
+        || (pNew->wsFlags & WHERE_COLUMN_NULL)!=0 
+        || (pNew->wsFlags & WHERE_COLUMN_IN)!=0 
+        || (pNew->wsFlags & WHERE_SKIPSCAN)!=0 
+    );
+
+    if( eOp & WO_IN ){
+      Expr *pExpr = pTerm->pExpr;
+      pNew->wsFlags |= WHERE_COLUMN_IN;
+      if( ExprHasProperty(pExpr, EP_xIsSelect) ){
+        /* "x IN (SELECT ...)":  TUNING: the SELECT returns 25 rows */
+        int i;
+        nIn = 46;  assert( 46==sqlite3LogEst(25) );
+
+        /* The expression may actually be of the form (x, y) IN (SELECT...).
+        ** In this case there is a separate term for each of (x) and (y).
+        ** However, the nIn multiplier should only be applied once, not once
+        ** for each such term. The following loop checks that pTerm is the
+        ** first such term in use, and sets nIn back to 0 if it is not. */
+        for(i=0; i<pNew->nLTerm-1; i++){
+          if( pNew->aLTerm[i] && pNew->aLTerm[i]->pExpr==pExpr ) nIn = 0;
+        }
+      }else if( ALWAYS(pExpr->x.pList && pExpr->x.pList->nExpr) ){
+        /* "x IN (value, value, ...)" */
+        nIn = sqlite3LogEst(pExpr->x.pList->nExpr);
+        assert( nIn>0 );  /* RHS always has 2 or more terms...  The parser
+                          ** changes "x IN (?)" into "x=?". */
+      }
+    }else if( eOp & (WO_EQ|WO_IS) ){
+      int iCol = pProbe->aiColumn[saved_nEq];
+      pNew->wsFlags |= WHERE_COLUMN_EQ;
+      assert( saved_nEq==pNew->u.btree.nEq );
+      if( iCol==XN_ROWID 
+       || (iCol>0 && nInMul==0 && saved_nEq==pProbe->nKeyCol-1)
+      ){
+        if( iCol>=0 && pProbe->uniqNotNull==0 ){
+          pNew->wsFlags |= WHERE_UNQ_WANTED;
+        }else{
+          pNew->wsFlags |= WHERE_ONEROW;
+        }
+      }
+    }else if( eOp & WO_ISNULL ){
+      pNew->wsFlags |= WHERE_COLUMN_NULL;
+    }else if( eOp & (WO_GT|WO_GE) ){
+      testcase( eOp & WO_GT );
+      testcase( eOp & WO_GE );
+      pNew->wsFlags |= WHERE_COLUMN_RANGE|WHERE_BTM_LIMIT;
+      pNew->u.btree.nBtm = whereRangeVectorLen(
+          pParse, pSrc->iCursor, pProbe, saved_nEq, pTerm
+      );
+      pBtm = pTerm;
+      pTop = 0;
+      if( pTerm->wtFlags & TERM_LIKEOPT ){
+        /* Range contraints that come from the LIKE optimization are
+        ** always used in pairs. */
+        pTop = &pTerm[1];
+        assert( (pTop-(pTerm->pWC->a))<pTerm->pWC->nTerm );
+        assert( pTop->wtFlags & TERM_LIKEOPT );
+        assert( pTop->eOperator==WO_LT );
+        if( whereLoopResize(db, pNew, pNew->nLTerm+1) ) break; /* OOM */
+        pNew->aLTerm[pNew->nLTerm++] = pTop;
+        pNew->wsFlags |= WHERE_TOP_LIMIT;
+        pNew->u.btree.nTop = 1;
+      }
+    }else{
+      assert( eOp & (WO_LT|WO_LE) );
+      testcase( eOp & WO_LT );
+      testcase( eOp & WO_LE );
+      pNew->wsFlags |= WHERE_COLUMN_RANGE|WHERE_TOP_LIMIT;
+      pNew->u.btree.nTop = whereRangeVectorLen(
+          pParse, pSrc->iCursor, pProbe, saved_nEq, pTerm
+      );
+      pTop = pTerm;
+      pBtm = (pNew->wsFlags & WHERE_BTM_LIMIT)!=0 ?
+                     pNew->aLTerm[pNew->nLTerm-2] : 0;
+    }
+
+    /* At this point pNew->nOut is set to the number of rows expected to
+    ** be visited by the index scan before considering term pTerm, or the
+    ** values of nIn and nInMul. In other words, assuming that all 
+    ** "x IN(...)" terms are replaced with "x = ?". This block updates
+    ** the value of pNew->nOut to account for pTerm (but not nIn/nInMul).  */
+    assert( pNew->nOut==saved_nOut );
+    if( pNew->wsFlags & WHERE_COLUMN_RANGE ){
+      /* Adjust nOut using stat3/stat4 data. Or, if there is no stat3/stat4
+      ** data, using some other estimate.  */
+      whereRangeScanEst(pParse, pBuilder, pBtm, pTop, pNew);
+    }else{
+      int nEq = ++pNew->u.btree.nEq;
+      assert( eOp & (WO_ISNULL|WO_EQ|WO_IN|WO_IS) );
+
+      assert( pNew->nOut==saved_nOut );
+      if( pTerm->truthProb<=0 && pProbe->aiColumn[saved_nEq]>=0 ){
+        assert( (eOp & WO_IN) || nIn==0 );
+        testcase( eOp & WO_IN );
+        pNew->nOut += pTerm->truthProb;
+        pNew->nOut -= nIn;
+      }else{
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+        tRowcnt nOut = 0;
+        if( nInMul==0 
+         && pProbe->nSample 
+         && pNew->u.btree.nEq<=pProbe->nSampleCol
+         && ((eOp & WO_IN)==0 || !ExprHasProperty(pTerm->pExpr, EP_xIsSelect))
+        ){
+          Expr *pExpr = pTerm->pExpr;
+          if( (eOp & (WO_EQ|WO_ISNULL|WO_IS))!=0 ){
+            testcase( eOp & WO_EQ );
+            testcase( eOp & WO_IS );
+            testcase( eOp & WO_ISNULL );
+            rc = whereEqualScanEst(pParse, pBuilder, pExpr->pRight, &nOut);
+          }else{
+            rc = whereInScanEst(pParse, pBuilder, pExpr->x.pList, &nOut);
+          }
+          if( rc==SQLITE_NOTFOUND ) rc = SQLITE_OK;
+          if( rc!=SQLITE_OK ) break;          /* Jump out of the pTerm loop */
+          if( nOut ){
+            pNew->nOut = sqlite3LogEst(nOut);
+            if( pNew->nOut>saved_nOut ) pNew->nOut = saved_nOut;
+            pNew->nOut -= nIn;
+          }
+        }
+        if( nOut==0 )
+#endif
+        {
+          pNew->nOut += (pProbe->aiRowLogEst[nEq] - pProbe->aiRowLogEst[nEq-1]);
+          if( eOp & WO_ISNULL ){
+            /* TUNING: If there is no likelihood() value, assume that a 
+            ** "col IS NULL" expression matches twice as many rows 
+            ** as (col=?). */
+            pNew->nOut += 10;
+          }
+        }
+      }
+    }
+
+    /* Set rCostIdx to the cost of visiting selected rows in index. Add
+    ** it to pNew->rRun, which is currently set to the cost of the index
+    ** seek only. Then, if this is a non-covering index, add the cost of
+    ** visiting the rows in the main table.  */
+    rCostIdx = pNew->nOut + 1 + (15*pProbe->szIdxRow)/pSrc->pTab->szTabRow;
+    pNew->rRun = sqlite3LogEstAdd(rLogSize, rCostIdx);
+    if( (pNew->wsFlags & (WHERE_IDX_ONLY|WHERE_IPK))==0 ){
+      pNew->rRun = sqlite3LogEstAdd(pNew->rRun, pNew->nOut + 16);
+    }
+    ApplyCostMultiplier(pNew->rRun, pProbe->pTable->costMult);
+
+    nOutUnadjusted = pNew->nOut;
+    pNew->rRun += nInMul + nIn;
+    pNew->nOut += nInMul + nIn;
+    whereLoopOutputAdjust(pBuilder->pWC, pNew, rSize);
+    rc = whereLoopInsert(pBuilder, pNew);
+
+    if( pNew->wsFlags & WHERE_COLUMN_RANGE ){
+      pNew->nOut = saved_nOut;
+    }else{
+      pNew->nOut = nOutUnadjusted;
+    }
+
+    if( (pNew->wsFlags & WHERE_TOP_LIMIT)==0
+     && pNew->u.btree.nEq<pProbe->nColumn
+    ){
+      whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nInMul+nIn);
+    }
+    pNew->nOut = saved_nOut;
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+    pBuilder->nRecValid = nRecValid;
+#endif
+  }
+  pNew->prereq = saved_prereq;
+  pNew->u.btree.nEq = saved_nEq;
+  pNew->u.btree.nBtm = saved_nBtm;
+  pNew->u.btree.nTop = saved_nTop;
+  pNew->nSkip = saved_nSkip;
+  pNew->wsFlags = saved_wsFlags;
+  pNew->nOut = saved_nOut;
+  pNew->nLTerm = saved_nLTerm;
+
+  /* Consider using a skip-scan if there are no WHERE clause constraints
+  ** available for the left-most terms of the index, and if the average
+  ** number of repeats in the left-most terms is at least 18. 
+  **
+  ** The magic number 18 is selected on the basis that scanning 17 rows
+  ** is almost always quicker than an index seek (even though if the index
+  ** contains fewer than 2^17 rows we assume otherwise in other parts of
+  ** the code). And, even if it is not, it should not be too much slower. 
+  ** On the other hand, the extra seeks could end up being significantly
+  ** more expensive.  */
+  assert( 42==sqlite3LogEst(18) );
+  if( saved_nEq==saved_nSkip
+   && saved_nEq+1<pProbe->nKeyCol
+   && pProbe->noSkipScan==0
+   && pProbe->aiRowLogEst[saved_nEq+1]>=42  /* TUNING: Minimum for skip-scan */
+   && (rc = whereLoopResize(db, pNew, pNew->nLTerm+1))==SQLITE_OK
+  ){
+    LogEst nIter;
+    pNew->u.btree.nEq++;
+    pNew->nSkip++;
+    pNew->aLTerm[pNew->nLTerm++] = 0;
+    pNew->wsFlags |= WHERE_SKIPSCAN;
+    nIter = pProbe->aiRowLogEst[saved_nEq] - pProbe->aiRowLogEst[saved_nEq+1];
+    pNew->nOut -= nIter;
+    /* TUNING:  Because uncertainties in the estimates for skip-scan queries,
+    ** add a 1.375 fudge factor to make skip-scan slightly less likely. */
+    nIter += 5;
+    whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nIter + nInMul);
+    pNew->nOut = saved_nOut;
+    pNew->u.btree.nEq = saved_nEq;
+    pNew->nSkip = saved_nSkip;
+    pNew->wsFlags = saved_wsFlags;
+  }
+
+  WHERETRACE(0x800, ("END addBtreeIdx(%s), nEq=%d, rc=%d\n",
+                      pProbe->zName, saved_nEq, rc));
+  return rc;
+}
+
+/*
+** Return True if it is possible that pIndex might be useful in
+** implementing the ORDER BY clause in pBuilder.
+**
+** Return False if pBuilder does not contain an ORDER BY clause or
+** if there is no way for pIndex to be useful in implementing that
+** ORDER BY clause.
+*/
+static int indexMightHelpWithOrderBy(
+  WhereLoopBuilder *pBuilder,
+  Index *pIndex,
+  int iCursor
+){
+  ExprList *pOB;
+  ExprList *aColExpr;
+  int ii, jj;
+
+  if( pIndex->bUnordered ) return 0;
+  if( (pOB = pBuilder->pWInfo->pOrderBy)==0 ) return 0;
+  for(ii=0; ii<pOB->nExpr; ii++){
+    Expr *pExpr = sqlite3ExprSkipCollate(pOB->a[ii].pExpr);
+    if( pExpr->op==TK_COLUMN && pExpr->iTable==iCursor ){
+      if( pExpr->iColumn<0 ) return 1;
+      for(jj=0; jj<pIndex->nKeyCol; jj++){
+        if( pExpr->iColumn==pIndex->aiColumn[jj] ) return 1;
+      }
+    }else if( (aColExpr = pIndex->aColExpr)!=0 ){
+      for(jj=0; jj<pIndex->nKeyCol; jj++){
+        if( pIndex->aiColumn[jj]!=XN_EXPR ) continue;
+        if( sqlite3ExprCompare(pExpr,aColExpr->a[jj].pExpr,iCursor)==0 ){
+          return 1;
+        }
+      }
+    }
+  }
+  return 0;
+}
+
+/*
+** Return a bitmask where 1s indicate that the corresponding column of
+** the table is used by an index.  Only the first 63 columns are considered.
+*/
+static Bitmask columnsInIndex(Index *pIdx){
+  Bitmask m = 0;
+  int j;
+  for(j=pIdx->nColumn-1; j>=0; j--){
+    int x = pIdx->aiColumn[j];
+    if( x>=0 ){
+      testcase( x==BMS-1 );
+      testcase( x==BMS-2 );
+      if( x<BMS-1 ) m |= MASKBIT(x);
+    }
+  }
+  return m;
+}
+
+/* Check to see if a partial index with pPartIndexWhere can be used
+** in the current query.  Return true if it can be and false if not.
+*/
+static int whereUsablePartialIndex(int iTab, WhereClause *pWC, Expr *pWhere){
+  int i;
+  WhereTerm *pTerm;
+  while( pWhere->op==TK_AND ){
+    if( !whereUsablePartialIndex(iTab,pWC,pWhere->pLeft) ) return 0;
+    pWhere = pWhere->pRight;
+  }
+  for(i=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
+    Expr *pExpr = pTerm->pExpr;
+    if( sqlite3ExprImpliesExpr(pExpr, pWhere, iTab) 
+     && (!ExprHasProperty(pExpr, EP_FromJoin) || pExpr->iRightJoinTable==iTab)
+    ){
+      return 1;
+    }
+  }
+  return 0;
+}
+
+/*
+** Add all WhereLoop objects for a single table of the join where the table
+** is identified by pBuilder->pNew->iTab.  That table is guaranteed to be
+** a b-tree table, not a virtual table.
+**
+** The costs (WhereLoop.rRun) of the b-tree loops added by this function
+** are calculated as follows:
+**
+** For a full scan, assuming the table (or index) contains nRow rows:
+**
+**     cost = nRow * 3.0                    // full-table scan
+**     cost = nRow * K                      // scan of covering index
+**     cost = nRow * (K+3.0)                // scan of non-covering index
+**
+** where K is a value between 1.1 and 3.0 set based on the relative 
+** estimated average size of the index and table records.
+**
+** For an index scan, where nVisit is the number of index rows visited
+** by the scan, and nSeek is the number of seek operations required on 
+** the index b-tree:
+**
+**     cost = nSeek * (log(nRow) + K * nVisit)          // covering index
+**     cost = nSeek * (log(nRow) + (K+3.0) * nVisit)    // non-covering index
+**
+** Normally, nSeek is 1. nSeek values greater than 1 come about if the 
+** WHERE clause includes "x IN (....)" terms used in place of "x=?". Or when 
+** implicit "x IN (SELECT x FROM tbl)" terms are added for skip-scans.
+**
+** The estimated values (nRow, nVisit, nSeek) often contain a large amount
+** of uncertainty.  For this reason, scoring is designed to pick plans that
+** "do the least harm" if the estimates are inaccurate.  For example, a
+** log(nRow) factor is omitted from a non-covering index scan in order to
+** bias the scoring in favor of using an index, since the worst-case
+** performance of using an index is far better than the worst-case performance
+** of a full table scan.
+*/
+static int whereLoopAddBtree(
+  WhereLoopBuilder *pBuilder, /* WHERE clause information */
+  Bitmask mPrereq             /* Extra prerequesites for using this table */
+){
+  WhereInfo *pWInfo;          /* WHERE analysis context */
+  Index *pProbe;              /* An index we are evaluating */
+  Index sPk;                  /* A fake index object for the primary key */
+  LogEst aiRowEstPk[2];       /* The aiRowLogEst[] value for the sPk index */
+  i16 aiColumnPk = -1;        /* The aColumn[] value for the sPk index */
+  SrcList *pTabList;          /* The FROM clause */
+  struct SrcList_item *pSrc;  /* The FROM clause btree term to add */
+  WhereLoop *pNew;            /* Template WhereLoop object */
+  int rc = SQLITE_OK;         /* Return code */
+  int iSortIdx = 1;           /* Index number */
+  int b;                      /* A boolean value */
+  LogEst rSize;               /* number of rows in the table */
+  LogEst rLogSize;            /* Logarithm of the number of rows in the table */
+  WhereClause *pWC;           /* The parsed WHERE clause */
+  Table *pTab;                /* Table being queried */
+  
+  pNew = pBuilder->pNew;
+  pWInfo = pBuilder->pWInfo;
+  pTabList = pWInfo->pTabList;
+  pSrc = pTabList->a + pNew->iTab;
+  pTab = pSrc->pTab;
+  pWC = pBuilder->pWC;
+  assert( !IsVirtual(pSrc->pTab) );
+
+  if( pSrc->pIBIndex ){
+    /* An INDEXED BY clause specifies a particular index to use */
+    pProbe = pSrc->pIBIndex;
+  }else if( !HasRowid(pTab) ){
+    pProbe = pTab->pIndex;
+  }else{
+    /* There is no INDEXED BY clause.  Create a fake Index object in local
+    ** variable sPk to represent the rowid primary key index.  Make this
+    ** fake index the first in a chain of Index objects with all of the real
+    ** indices to follow */
+    Index *pFirst;                  /* First of real indices on the table */
+    memset(&sPk, 0, sizeof(Index));
+    sPk.nKeyCol = 1;
+    sPk.nColumn = 1;
+    sPk.aiColumn = &aiColumnPk;
+    sPk.aiRowLogEst = aiRowEstPk;
+    sPk.onError = OE_Replace;
+    sPk.pTable = pTab;
+    sPk.szIdxRow = pTab->szTabRow;
+    aiRowEstPk[0] = pTab->nRowLogEst;
+    aiRowEstPk[1] = 0;
+    pFirst = pSrc->pTab->pIndex;
+    if( pSrc->fg.notIndexed==0 ){
+      /* The real indices of the table are only considered if the
+      ** NOT INDEXED qualifier is omitted from the FROM clause */
+      sPk.pNext = pFirst;
+    }
+    pProbe = &sPk;
+  }
+  rSize = pTab->nRowLogEst;
+  rLogSize = estLog(rSize);
+
+#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
+  /* Automatic indexes */
+  if( !pBuilder->pOrSet      /* Not part of an OR optimization */
+   && (pWInfo->wctrlFlags & WHERE_OR_SUBCLAUSE)==0
+   && (pWInfo->pParse->db->flags & SQLITE_AutoIndex)!=0
+   && pSrc->pIBIndex==0      /* Has no INDEXED BY clause */
+   && !pSrc->fg.notIndexed   /* Has no NOT INDEXED clause */
+   && HasRowid(pTab)         /* Not WITHOUT ROWID table. (FIXME: Why not?) */
+   && !pSrc->fg.isCorrelated /* Not a correlated subquery */
+   && !pSrc->fg.isRecursive  /* Not a recursive common table expression. */
+  ){
+    /* Generate auto-index WhereLoops */
+    WhereTerm *pTerm;
+    WhereTerm *pWCEnd = pWC->a + pWC->nTerm;
+    for(pTerm=pWC->a; rc==SQLITE_OK && pTerm<pWCEnd; pTerm++){
+      if( pTerm->prereqRight & pNew->maskSelf ) continue;
+      if( termCanDriveIndex(pTerm, pSrc, 0) ){
+        pNew->u.btree.nEq = 1;
+        pNew->nSkip = 0;
+        pNew->u.btree.pIndex = 0;
+        pNew->nLTerm = 1;
+        pNew->aLTerm[0] = pTerm;
+        /* TUNING: One-time cost for computing the automatic index is
+        ** estimated to be X*N*log2(N) where N is the number of rows in
+        ** the table being indexed and where X is 7 (LogEst=28) for normal
+        ** tables or 1.375 (LogEst=4) for views and subqueries.  The value
+        ** of X is smaller for views and subqueries so that the query planner
+        ** will be more aggressive about generating automatic indexes for
+        ** those objects, since there is no opportunity to add schema
+        ** indexes on subqueries and views. */
+        pNew->rSetup = rLogSize + rSize + 4;
+        if( pTab->pSelect==0 && (pTab->tabFlags & TF_Ephemeral)==0 ){
+          pNew->rSetup += 24;
+        }
+        ApplyCostMultiplier(pNew->rSetup, pTab->costMult);
+        if( pNew->rSetup<0 ) pNew->rSetup = 0;
+        /* TUNING: Each index lookup yields 20 rows in the table.  This
+        ** is more than the usual guess of 10 rows, since we have no way
+        ** of knowing how selective the index will ultimately be.  It would
+        ** not be unreasonable to make this value much larger. */
+        pNew->nOut = 43;  assert( 43==sqlite3LogEst(20) );
+        pNew->rRun = sqlite3LogEstAdd(rLogSize,pNew->nOut);
+        pNew->wsFlags = WHERE_AUTO_INDEX;
+        pNew->prereq = mPrereq | pTerm->prereqRight;
+        rc = whereLoopInsert(pBuilder, pNew);
+      }
+    }
+  }
+#endif /* SQLITE_OMIT_AUTOMATIC_INDEX */
+
+  /* Loop over all indices
+  */
+  for(; rc==SQLITE_OK && pProbe; pProbe=pProbe->pNext, iSortIdx++){
+    if( pProbe->pPartIdxWhere!=0
+     && !whereUsablePartialIndex(pSrc->iCursor, pWC, pProbe->pPartIdxWhere) ){
+      testcase( pNew->iTab!=pSrc->iCursor );  /* See ticket [98d973b8f5] */
+      continue;  /* Partial index inappropriate for this query */
+    }
+    rSize = pProbe->aiRowLogEst[0];
+    pNew->u.btree.nEq = 0;
+    pNew->u.btree.nBtm = 0;
+    pNew->u.btree.nTop = 0;
+    pNew->nSkip = 0;
+    pNew->nLTerm = 0;
+    pNew->iSortIdx = 0;
+    pNew->rSetup = 0;
+    pNew->prereq = mPrereq;
+    pNew->nOut = rSize;
+    pNew->u.btree.pIndex = pProbe;
+    b = indexMightHelpWithOrderBy(pBuilder, pProbe, pSrc->iCursor);
+    /* The ONEPASS_DESIRED flags never occurs together with ORDER BY */
+    assert( (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || b==0 );
+    if( pProbe->tnum<=0 ){
+      /* Integer primary key index */
+      pNew->wsFlags = WHERE_IPK;
+
+      /* Full table scan */
+      pNew->iSortIdx = b ? iSortIdx : 0;
+      /* TUNING: Cost of full table scan is (N*3.0). */
+      pNew->rRun = rSize + 16;
+      ApplyCostMultiplier(pNew->rRun, pTab->costMult);
+      whereLoopOutputAdjust(pWC, pNew, rSize);
+      rc = whereLoopInsert(pBuilder, pNew);
+      pNew->nOut = rSize;
+      if( rc ) break;
+    }else{
+      Bitmask m;
+      if( pProbe->isCovering ){
+        pNew->wsFlags = WHERE_IDX_ONLY | WHERE_INDEXED;
+        m = 0;
+      }else{
+        m = pSrc->colUsed & ~columnsInIndex(pProbe);
+        pNew->wsFlags = (m==0) ? (WHERE_IDX_ONLY|WHERE_INDEXED) : WHERE_INDEXED;
+      }
+
+      /* Full scan via index */
+      if( b
+       || !HasRowid(pTab)
+       || pProbe->pPartIdxWhere!=0
+       || ( m==0
+         && pProbe->bUnordered==0
+         && (pProbe->szIdxRow<pTab->szTabRow)
+         && (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0
+         && sqlite3GlobalConfig.bUseCis
+         && OptimizationEnabled(pWInfo->pParse->db, SQLITE_CoverIdxScan)
+          )
+      ){
+        pNew->iSortIdx = b ? iSortIdx : 0;
+
+        /* The cost of visiting the index rows is N*K, where K is
+        ** between 1.1 and 3.0, depending on the relative sizes of the
+        ** index and table rows. */
+        pNew->rRun = rSize + 1 + (15*pProbe->szIdxRow)/pTab->szTabRow;
+        if( m!=0 ){
+          /* If this is a non-covering index scan, add in the cost of
+          ** doing table lookups.  The cost will be 3x the number of
+          ** lookups.  Take into account WHERE clause terms that can be
+          ** satisfied using just the index, and that do not require a
+          ** table lookup. */
+          LogEst nLookup = rSize + 16;  /* Base cost:  N*3 */
+          int ii;
+          int iCur = pSrc->iCursor;
+          WhereClause *pWC2 = &pWInfo->sWC;
+          for(ii=0; ii<pWC2->nTerm; ii++){
+            WhereTerm *pTerm = &pWC2->a[ii];
+            if( !sqlite3ExprCoveredByIndex(pTerm->pExpr, iCur, pProbe) ){
+              break;
+            }
+            /* pTerm can be evaluated using just the index.  So reduce
+            ** the expected number of table lookups accordingly */
+            if( pTerm->truthProb<=0 ){
+              nLookup += pTerm->truthProb;
+            }else{
+              nLookup--;
+              if( pTerm->eOperator & (WO_EQ|WO_IS) ) nLookup -= 19;
+            }
+          }
+          
+          pNew->rRun = sqlite3LogEstAdd(pNew->rRun, nLookup);
+        }
+        ApplyCostMultiplier(pNew->rRun, pTab->costMult);
+        whereLoopOutputAdjust(pWC, pNew, rSize);
+        rc = whereLoopInsert(pBuilder, pNew);
+        pNew->nOut = rSize;
+        if( rc ) break;
+      }
+    }
+
+    rc = whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, 0);
+#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
+    sqlite3Stat4ProbeFree(pBuilder->pRec);
+    pBuilder->nRecValid = 0;
+    pBuilder->pRec = 0;
+#endif
+
+    /* If there was an INDEXED BY clause, then only that one index is
+    ** considered. */
+    if( pSrc->pIBIndex ) break;
+  }
+  return rc;
+}
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+
+/*
+** Argument pIdxInfo is already populated with all constraints that may
+** be used by the virtual table identified by pBuilder->pNew->iTab. This
+** function marks a subset of those constraints usable, invokes the
+** xBestIndex method and adds the returned plan to pBuilder.
+**
+** A constraint is marked usable if:
+**
+**   * Argument mUsable indicates that its prerequisites are available, and
+**
+**   * It is not one of the operators specified in the mExclude mask passed
+**     as the fourth argument (which in practice is either WO_IN or 0).
+**
+** Argument mPrereq is a mask of tables that must be scanned before the
+** virtual table in question. These are added to the plans prerequisites
+** before it is added to pBuilder.
+**
+** Output parameter *pbIn is set to true if the plan added to pBuilder
+** uses one or more WO_IN terms, or false otherwise.
+*/
+static int whereLoopAddVirtualOne(
+  WhereLoopBuilder *pBuilder,
+  Bitmask mPrereq,                /* Mask of tables that must be used. */
+  Bitmask mUsable,                /* Mask of usable tables */
+  u16 mExclude,                   /* Exclude terms using these operators */
+  sqlite3_index_info *pIdxInfo,   /* Populated object for xBestIndex */
+  u16 mNoOmit,                    /* Do not omit these constraints */
+  int *pbIn                       /* OUT: True if plan uses an IN(...) op */
+){
+  WhereClause *pWC = pBuilder->pWC;
+  struct sqlite3_index_constraint *pIdxCons;
+  struct sqlite3_index_constraint_usage *pUsage = pIdxInfo->aConstraintUsage;
+  int i;
+  int mxTerm;
+  int rc = SQLITE_OK;
+  WhereLoop *pNew = pBuilder->pNew;
+  Parse *pParse = pBuilder->pWInfo->pParse;
+  struct SrcList_item *pSrc = &pBuilder->pWInfo->pTabList->a[pNew->iTab];
+  int nConstraint = pIdxInfo->nConstraint;
+
+  assert( (mUsable & mPrereq)==mPrereq );
+  *pbIn = 0;
+  pNew->prereq = mPrereq;
+
+  /* Set the usable flag on the subset of constraints identified by 
+  ** arguments mUsable and mExclude. */
+  pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint;
+  for(i=0; i<nConstraint; i++, pIdxCons++){
+    WhereTerm *pTerm = &pWC->a[pIdxCons->iTermOffset];
+    pIdxCons->usable = 0;
+    if( (pTerm->prereqRight & mUsable)==pTerm->prereqRight 
+     && (pTerm->eOperator & mExclude)==0
+    ){
+      pIdxCons->usable = 1;
+    }
+  }
+
+  /* Initialize the output fields of the sqlite3_index_info structure */
+  memset(pUsage, 0, sizeof(pUsage[0])*nConstraint);
+  assert( pIdxInfo->needToFreeIdxStr==0 );
+  pIdxInfo->idxStr = 0;
+  pIdxInfo->idxNum = 0;
+  pIdxInfo->orderByConsumed = 0;
+  pIdxInfo->estimatedCost = SQLITE_BIG_DBL / (double)2;
+  pIdxInfo->estimatedRows = 25;
+  pIdxInfo->idxFlags = 0;
+  pIdxInfo->colUsed = (sqlite3_int64)pSrc->colUsed;
+
+  /* Invoke the virtual table xBestIndex() method */
+  rc = vtabBestIndex(pParse, pSrc->pTab, pIdxInfo);
+  if( rc ) return rc;
+
+  mxTerm = -1;
+  assert( pNew->nLSlot>=nConstraint );
+  for(i=0; i<nConstraint; i++) pNew->aLTerm[i] = 0;
+  pNew->u.vtab.omitMask = 0;
+  pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint;
+  for(i=0; i<nConstraint; i++, pIdxCons++){
+    int iTerm;
+    if( (iTerm = pUsage[i].argvIndex - 1)>=0 ){
+      WhereTerm *pTerm;
+      int j = pIdxCons->iTermOffset;
+      if( iTerm>=nConstraint
+       || j<0
+       || j>=pWC->nTerm
+       || pNew->aLTerm[iTerm]!=0
+       || pIdxCons->usable==0
+      ){
+        rc = SQLITE_ERROR;
+        sqlite3ErrorMsg(pParse,"%s.xBestIndex malfunction",pSrc->pTab->zName);
+        return rc;
+      }
+      testcase( iTerm==nConstraint-1 );
+      testcase( j==0 );
+      testcase( j==pWC->nTerm-1 );
+      pTerm = &pWC->a[j];
+      pNew->prereq |= pTerm->prereqRight;
+      assert( iTerm<pNew->nLSlot );
+      pNew->aLTerm[iTerm] = pTerm;
+      if( iTerm>mxTerm ) mxTerm = iTerm;
+      testcase( iTerm==15 );
+      testcase( iTerm==16 );
+      if( iTerm<16 && pUsage[i].omit ) pNew->u.vtab.omitMask |= 1<<iTerm;
+      if( (pTerm->eOperator & WO_IN)!=0 ){
+        /* A virtual table that is constrained by an IN clause may not
+        ** consume the ORDER BY clause because (1) the order of IN terms
+        ** is not necessarily related to the order of output terms and
+        ** (2) Multiple outputs from a single IN value will not merge
+        ** together.  */
+        pIdxInfo->orderByConsumed = 0;
+        pIdxInfo->idxFlags &= ~SQLITE_INDEX_SCAN_UNIQUE;
+        *pbIn = 1; assert( (mExclude & WO_IN)==0 );
+      }
+    }
+  }
+  pNew->u.vtab.omitMask &= ~mNoOmit;
+
+  pNew->nLTerm = mxTerm+1;
+  assert( pNew->nLTerm<=pNew->nLSlot );
+  pNew->u.vtab.idxNum = pIdxInfo->idxNum;
+  pNew->u.vtab.needFree = pIdxInfo->needToFreeIdxStr;
+  pIdxInfo->needToFreeIdxStr = 0;
+  pNew->u.vtab.idxStr = pIdxInfo->idxStr;
+  pNew->u.vtab.isOrdered = (i8)(pIdxInfo->orderByConsumed ?
+      pIdxInfo->nOrderBy : 0);
+  pNew->rSetup = 0;
+  pNew->rRun = sqlite3LogEstFromDouble(pIdxInfo->estimatedCost);
+  pNew->nOut = sqlite3LogEst(pIdxInfo->estimatedRows);
+
+  /* Set the WHERE_ONEROW flag if the xBestIndex() method indicated
+  ** that the scan will visit at most one row. Clear it otherwise. */
+  if( pIdxInfo->idxFlags & SQLITE_INDEX_SCAN_UNIQUE ){
+    pNew->wsFlags |= WHERE_ONEROW;
+  }else{
+    pNew->wsFlags &= ~WHERE_ONEROW;
+  }
+  rc = whereLoopInsert(pBuilder, pNew);
+  if( pNew->u.vtab.needFree ){
+    sqlite3_free(pNew->u.vtab.idxStr);
+    pNew->u.vtab.needFree = 0;
+  }
+  WHERETRACE(0xffff, ("  bIn=%d prereqIn=%04llx prereqOut=%04llx\n",
+                      *pbIn, (sqlite3_uint64)mPrereq,
+                      (sqlite3_uint64)(pNew->prereq & ~mPrereq)));
+
+  return rc;
+}
+
+
+/*
+** Add all WhereLoop objects for a table of the join identified by
+** pBuilder->pNew->iTab.  That table is guaranteed to be a virtual table.
+**
+** If there are no LEFT or CROSS JOIN joins in the query, both mPrereq and
+** mUnusable are set to 0. Otherwise, mPrereq is a mask of all FROM clause
+** entries that occur before the virtual table in the FROM clause and are
+** separated from it by at least one LEFT or CROSS JOIN. Similarly, the
+** mUnusable mask contains all FROM clause entries that occur after the
+** virtual table and are separated from it by at least one LEFT or 
+** CROSS JOIN. 
+**
+** For example, if the query were:
+**
+**   ... FROM t1, t2 LEFT JOIN t3, t4, vt CROSS JOIN t5, t6;
+**
+** then mPrereq corresponds to (t1, t2) and mUnusable to (t5, t6).
+**
+** All the tables in mPrereq must be scanned before the current virtual 
+** table. So any terms for which all prerequisites are satisfied by 
+** mPrereq may be specified as "usable" in all calls to xBestIndex. 
+** Conversely, all tables in mUnusable must be scanned after the current
+** virtual table, so any terms for which the prerequisites overlap with
+** mUnusable should always be configured as "not-usable" for xBestIndex.
+*/
+static int whereLoopAddVirtual(
+  WhereLoopBuilder *pBuilder,  /* WHERE clause information */
+  Bitmask mPrereq,             /* Tables that must be scanned before this one */
+  Bitmask mUnusable            /* Tables that must be scanned after this one */
+){
+  int rc = SQLITE_OK;          /* Return code */
+  WhereInfo *pWInfo;           /* WHERE analysis context */
+  Parse *pParse;               /* The parsing context */
+  WhereClause *pWC;            /* The WHERE clause */
+  struct SrcList_item *pSrc;   /* The FROM clause term to search */
+  sqlite3_index_info *p;       /* Object to pass to xBestIndex() */
+  int nConstraint;             /* Number of constraints in p */
+  int bIn;                     /* True if plan uses IN(...) operator */
+  WhereLoop *pNew;
+  Bitmask mBest;               /* Tables used by best possible plan */
+  u16 mNoOmit;
+
+  assert( (mPrereq & mUnusable)==0 );
+  pWInfo = pBuilder->pWInfo;
+  pParse = pWInfo->pParse;
+  pWC = pBuilder->pWC;
+  pNew = pBuilder->pNew;
+  pSrc = &pWInfo->pTabList->a[pNew->iTab];
+  assert( IsVirtual(pSrc->pTab) );
+  p = allocateIndexInfo(pParse, pWC, mUnusable, pSrc, pBuilder->pOrderBy, 
+      &mNoOmit);
+  if( p==0 ) return SQLITE_NOMEM_BKPT;
+  pNew->rSetup = 0;
+  pNew->wsFlags = WHERE_VIRTUALTABLE;
+  pNew->nLTerm = 0;
+  pNew->u.vtab.needFree = 0;
+  nConstraint = p->nConstraint;
+  if( whereLoopResize(pParse->db, pNew, nConstraint) ){
+    sqlite3DbFree(pParse->db, p);
+    return SQLITE_NOMEM_BKPT;
+  }
+
+  /* First call xBestIndex() with all constraints usable. */
+  WHERETRACE(0x40, ("  VirtualOne: all usable\n"));
+  rc = whereLoopAddVirtualOne(pBuilder, mPrereq, ALLBITS, 0, p, mNoOmit, &bIn);
+
+  /* If the call to xBestIndex() with all terms enabled produced a plan
+  ** that does not require any source tables (IOW: a plan with mBest==0),
+  ** then there is no point in making any further calls to xBestIndex() 
+  ** since they will all return the same result (if the xBestIndex()
+  ** implementation is sane). */
+  if( rc==SQLITE_OK && (mBest = (pNew->prereq & ~mPrereq))!=0 ){
+    int seenZero = 0;             /* True if a plan with no prereqs seen */
+    int seenZeroNoIN = 0;         /* Plan with no prereqs and no IN(...) seen */
+    Bitmask mPrev = 0;
+    Bitmask mBestNoIn = 0;
+
+    /* If the plan produced by the earlier call uses an IN(...) term, call
+    ** xBestIndex again, this time with IN(...) terms disabled. */
+    if( bIn ){
+      WHERETRACE(0x40, ("  VirtualOne: all usable w/o IN\n"));
+      rc = whereLoopAddVirtualOne(
+          pBuilder, mPrereq, ALLBITS, WO_IN, p, mNoOmit, &bIn);
+      assert( bIn==0 );
+      mBestNoIn = pNew->prereq & ~mPrereq;
+      if( mBestNoIn==0 ){
+        seenZero = 1;
+        seenZeroNoIN = 1;
+      }
+    }
+
+    /* Call xBestIndex once for each distinct value of (prereqRight & ~mPrereq) 
+    ** in the set of terms that apply to the current virtual table.  */
+    while( rc==SQLITE_OK ){
+      int i;
+      Bitmask mNext = ALLBITS;
+      assert( mNext>0 );
+      for(i=0; i<nConstraint; i++){
+        Bitmask mThis = (
+            pWC->a[p->aConstraint[i].iTermOffset].prereqRight & ~mPrereq
+        );
+        if( mThis>mPrev && mThis<mNext ) mNext = mThis;
+      }
+      mPrev = mNext;
+      if( mNext==ALLBITS ) break;
+      if( mNext==mBest || mNext==mBestNoIn ) continue;
+      WHERETRACE(0x40, ("  VirtualOne: mPrev=%04llx mNext=%04llx\n",
+                       (sqlite3_uint64)mPrev, (sqlite3_uint64)mNext));
+      rc = whereLoopAddVirtualOne(
+          pBuilder, mPrereq, mNext|mPrereq, 0, p, mNoOmit, &bIn);
+      if( pNew->prereq==mPrereq ){
+        seenZero = 1;
+        if( bIn==0 ) seenZeroNoIN = 1;
+      }
+    }
+
+    /* If the calls to xBestIndex() in the above loop did not find a plan
+    ** that requires no source tables at all (i.e. one guaranteed to be
+    ** usable), make a call here with all source tables disabled */
+    if( rc==SQLITE_OK && seenZero==0 ){
+      WHERETRACE(0x40, ("  VirtualOne: all disabled\n"));
+      rc = whereLoopAddVirtualOne(
+          pBuilder, mPrereq, mPrereq, 0, p, mNoOmit, &bIn);
+      if( bIn==0 ) seenZeroNoIN = 1;
+    }
+
+    /* If the calls to xBestIndex() have so far failed to find a plan
+    ** that requires no source tables at all and does not use an IN(...)
+    ** operator, make a final call to obtain one here.  */
+    if( rc==SQLITE_OK && seenZeroNoIN==0 ){
+      WHERETRACE(0x40, ("  VirtualOne: all disabled and w/o IN\n"));
+      rc = whereLoopAddVirtualOne(
+          pBuilder, mPrereq, mPrereq, WO_IN, p, mNoOmit, &bIn);
+    }
+  }
+
+  if( p->needToFreeIdxStr ) sqlite3_free(p->idxStr);
+  sqlite3DbFree(pParse->db, p);
+  return rc;
+}
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+/*
+** Add WhereLoop entries to handle OR terms.  This works for either
+** btrees or virtual tables.
+*/
+static int whereLoopAddOr(
+  WhereLoopBuilder *pBuilder, 
+  Bitmask mPrereq, 
+  Bitmask mUnusable
+){
+  WhereInfo *pWInfo = pBuilder->pWInfo;
+  WhereClause *pWC;
+  WhereLoop *pNew;
+  WhereTerm *pTerm, *pWCEnd;
+  int rc = SQLITE_OK;
+  int iCur;
+  WhereClause tempWC;
+  WhereLoopBuilder sSubBuild;
+  WhereOrSet sSum, sCur;
+  struct SrcList_item *pItem;
+  
+  pWC = pBuilder->pWC;
+  pWCEnd = pWC->a + pWC->nTerm;
+  pNew = pBuilder->pNew;
+  memset(&sSum, 0, sizeof(sSum));
+  pItem = pWInfo->pTabList->a + pNew->iTab;
+  iCur = pItem->iCursor;
+
+  for(pTerm=pWC->a; pTerm<pWCEnd && rc==SQLITE_OK; pTerm++){
+    if( (pTerm->eOperator & WO_OR)!=0
+     && (pTerm->u.pOrInfo->indexable & pNew->maskSelf)!=0 
+    ){
+      WhereClause * const pOrWC = &pTerm->u.pOrInfo->wc;
+      WhereTerm * const pOrWCEnd = &pOrWC->a[pOrWC->nTerm];
+      WhereTerm *pOrTerm;
+      int once = 1;
+      int i, j;
+    
+      sSubBuild = *pBuilder;
+      sSubBuild.pOrderBy = 0;
+      sSubBuild.pOrSet = &sCur;
+
+      WHERETRACE(0x200, ("Begin processing OR-clause %p\n", pTerm));
+      for(pOrTerm=pOrWC->a; pOrTerm<pOrWCEnd; pOrTerm++){
+        if( (pOrTerm->eOperator & WO_AND)!=0 ){
+          sSubBuild.pWC = &pOrTerm->u.pAndInfo->wc;
+        }else if( pOrTerm->leftCursor==iCur ){
+          tempWC.pWInfo = pWC->pWInfo;
+          tempWC.pOuter = pWC;
+          tempWC.op = TK_AND;
+          tempWC.nTerm = 1;
+          tempWC.a = pOrTerm;
+          sSubBuild.pWC = &tempWC;
+        }else{
+          continue;
+        }
+        sCur.n = 0;
+#ifdef WHERETRACE_ENABLED
+        WHERETRACE(0x200, ("OR-term %d of %p has %d subterms:\n", 
+                   (int)(pOrTerm-pOrWC->a), pTerm, sSubBuild.pWC->nTerm));
+        if( sqlite3WhereTrace & 0x400 ){
+          sqlite3WhereClausePrint(sSubBuild.pWC);
+        }
+#endif
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+        if( IsVirtual(pItem->pTab) ){
+          rc = whereLoopAddVirtual(&sSubBuild, mPrereq, mUnusable);
+        }else
+#endif
+        {
+          rc = whereLoopAddBtree(&sSubBuild, mPrereq);
+        }
+        if( rc==SQLITE_OK ){
+          rc = whereLoopAddOr(&sSubBuild, mPrereq, mUnusable);
+        }
+        assert( rc==SQLITE_OK || sCur.n==0 );
+        if( sCur.n==0 ){
+          sSum.n = 0;
+          break;
+        }else if( once ){
+          whereOrMove(&sSum, &sCur);
+          once = 0;
+        }else{
+          WhereOrSet sPrev;
+          whereOrMove(&sPrev, &sSum);
+          sSum.n = 0;
+          for(i=0; i<sPrev.n; i++){
+            for(j=0; j<sCur.n; j++){
+              whereOrInsert(&sSum, sPrev.a[i].prereq | sCur.a[j].prereq,
+                            sqlite3LogEstAdd(sPrev.a[i].rRun, sCur.a[j].rRun),
+                            sqlite3LogEstAdd(sPrev.a[i].nOut, sCur.a[j].nOut));
+            }
+          }
+        }
+      }
+      pNew->nLTerm = 1;
+      pNew->aLTerm[0] = pTerm;
+      pNew->wsFlags = WHERE_MULTI_OR;
+      pNew->rSetup = 0;
+      pNew->iSortIdx = 0;
+      memset(&pNew->u, 0, sizeof(pNew->u));
+      for(i=0; rc==SQLITE_OK && i<sSum.n; i++){
+        /* TUNING: Currently sSum.a[i].rRun is set to the sum of the costs
+        ** of all sub-scans required by the OR-scan. However, due to rounding
+        ** errors, it may be that the cost of the OR-scan is equal to its
+        ** most expensive sub-scan. Add the smallest possible penalty 
+        ** (equivalent to multiplying the cost by 1.07) to ensure that 
+        ** this does not happen. Otherwise, for WHERE clauses such as the
+        ** following where there is an index on "y":
+        **
+        **     WHERE likelihood(x=?, 0.99) OR y=?
+        **
+        ** the planner may elect to "OR" together a full-table scan and an
+        ** index lookup. And other similarly odd results.  */
+        pNew->rRun = sSum.a[i].rRun + 1;
+        pNew->nOut = sSum.a[i].nOut;
+        pNew->prereq = sSum.a[i].prereq;
+        rc = whereLoopInsert(pBuilder, pNew);
+      }
+      WHERETRACE(0x200, ("End processing OR-clause %p\n", pTerm));
+    }
+  }
+  return rc;
+}
+
+/*
+** Add all WhereLoop objects for all tables 
+*/
+static int whereLoopAddAll(WhereLoopBuilder *pBuilder){
+  WhereInfo *pWInfo = pBuilder->pWInfo;
+  Bitmask mPrereq = 0;
+  Bitmask mPrior = 0;
+  int iTab;
+  SrcList *pTabList = pWInfo->pTabList;
+  struct SrcList_item *pItem;
+  struct SrcList_item *pEnd = &pTabList->a[pWInfo->nLevel];
+  sqlite3 *db = pWInfo->pParse->db;
+  int rc = SQLITE_OK;
+  WhereLoop *pNew;
+  u8 priorJointype = 0;
+
+  /* Loop over the tables in the join, from left to right */
+  pNew = pBuilder->pNew;
+  whereLoopInit(pNew);
+  for(iTab=0, pItem=pTabList->a; pItem<pEnd; iTab++, pItem++){
+    Bitmask mUnusable = 0;
+    pNew->iTab = iTab;
+    pNew->maskSelf = sqlite3WhereGetMask(&pWInfo->sMaskSet, pItem->iCursor);
+    if( ((pItem->fg.jointype|priorJointype) & (JT_LEFT|JT_CROSS))!=0 ){
+      /* This condition is true when pItem is the FROM clause term on the
+      ** right-hand-side of a LEFT or CROSS JOIN.  */
+      mPrereq = mPrior;
+    }
+    priorJointype = pItem->fg.jointype;
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    if( IsVirtual(pItem->pTab) ){
+      struct SrcList_item *p;
+      for(p=&pItem[1]; p<pEnd; p++){
+        if( mUnusable || (p->fg.jointype & (JT_LEFT|JT_CROSS)) ){
+          mUnusable |= sqlite3WhereGetMask(&pWInfo->sMaskSet, p->iCursor);
+        }
+      }
+      rc = whereLoopAddVirtual(pBuilder, mPrereq, mUnusable);
+    }else
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+    {
+      rc = whereLoopAddBtree(pBuilder, mPrereq);
+    }
+    if( rc==SQLITE_OK ){
+      rc = whereLoopAddOr(pBuilder, mPrereq, mUnusable);
+    }
+    mPrior |= pNew->maskSelf;
+    if( rc || db->mallocFailed ) break;
+  }
+
+  whereLoopClear(db, pNew);
+  return rc;
+}
+
+/*
+** Examine a WherePath (with the addition of the extra WhereLoop of the 5th
+** parameters) to see if it outputs rows in the requested ORDER BY
+** (or GROUP BY) without requiring a separate sort operation.  Return N:
+** 
+**   N>0:   N terms of the ORDER BY clause are satisfied
+**   N==0:  No terms of the ORDER BY clause are satisfied
+**   N<0:   Unknown yet how many terms of ORDER BY might be satisfied.   
+**
+** Note that processing for WHERE_GROUPBY and WHERE_DISTINCTBY is not as
+** strict.  With GROUP BY and DISTINCT the only requirement is that
+** equivalent rows appear immediately adjacent to one another.  GROUP BY
+** and DISTINCT do not require rows to appear in any particular order as long
+** as equivalent rows are grouped together.  Thus for GROUP BY and DISTINCT
+** the pOrderBy terms can be matched in any order.  With ORDER BY, the 
+** pOrderBy terms must be matched in strict left-to-right order.
+*/
+static i8 wherePathSatisfiesOrderBy(
+  WhereInfo *pWInfo,    /* The WHERE clause */
+  ExprList *pOrderBy,   /* ORDER BY or GROUP BY or DISTINCT clause to check */
+  WherePath *pPath,     /* The WherePath to check */
+  u16 wctrlFlags,       /* WHERE_GROUPBY or _DISTINCTBY or _ORDERBY_LIMIT */
+  u16 nLoop,            /* Number of entries in pPath->aLoop[] */
+  WhereLoop *pLast,     /* Add this WhereLoop to the end of pPath->aLoop[] */
+  Bitmask *pRevMask     /* OUT: Mask of WhereLoops to run in reverse order */
+){
+  u8 revSet;            /* True if rev is known */
+  u8 rev;               /* Composite sort order */
+  u8 revIdx;            /* Index sort order */
+  u8 isOrderDistinct;   /* All prior WhereLoops are order-distinct */
+  u8 distinctColumns;   /* True if the loop has UNIQUE NOT NULL columns */
+  u8 isMatch;           /* iColumn matches a term of the ORDER BY clause */
+  u16 eqOpMask;         /* Allowed equality operators */
+  u16 nKeyCol;          /* Number of key columns in pIndex */
+  u16 nColumn;          /* Total number of ordered columns in the index */
+  u16 nOrderBy;         /* Number terms in the ORDER BY clause */
+  int iLoop;            /* Index of WhereLoop in pPath being processed */
+  int i, j;             /* Loop counters */
+  int iCur;             /* Cursor number for current WhereLoop */
+  int iColumn;          /* A column number within table iCur */
+  WhereLoop *pLoop = 0; /* Current WhereLoop being processed. */
+  WhereTerm *pTerm;     /* A single term of the WHERE clause */
+  Expr *pOBExpr;        /* An expression from the ORDER BY clause */
+  CollSeq *pColl;       /* COLLATE function from an ORDER BY clause term */
+  Index *pIndex;        /* The index associated with pLoop */
+  sqlite3 *db = pWInfo->pParse->db;  /* Database connection */
+  Bitmask obSat = 0;    /* Mask of ORDER BY terms satisfied so far */
+  Bitmask obDone;       /* Mask of all ORDER BY terms */
+  Bitmask orderDistinctMask;  /* Mask of all well-ordered loops */
+  Bitmask ready;              /* Mask of inner loops */
+
+  /*
+  ** We say the WhereLoop is "one-row" if it generates no more than one
+  ** row of output.  A WhereLoop is one-row if all of the following are true:
+  **  (a) All index columns match with WHERE_COLUMN_EQ.
+  **  (b) The index is unique
+  ** Any WhereLoop with an WHERE_COLUMN_EQ constraint on the rowid is one-row.
+  ** Every one-row WhereLoop will have the WHERE_ONEROW bit set in wsFlags.
+  **
+  ** We say the WhereLoop is "order-distinct" if the set of columns from
+  ** that WhereLoop that are in the ORDER BY clause are different for every
+  ** row of the WhereLoop.  Every one-row WhereLoop is automatically
+  ** order-distinct.   A WhereLoop that has no columns in the ORDER BY clause
+  ** is not order-distinct. To be order-distinct is not quite the same as being
+  ** UNIQUE since a UNIQUE column or index can have multiple rows that 
+  ** are NULL and NULL values are equivalent for the purpose of order-distinct.
+  ** To be order-distinct, the columns must be UNIQUE and NOT NULL.
+  **
+  ** The rowid for a table is always UNIQUE and NOT NULL so whenever the
+  ** rowid appears in the ORDER BY clause, the corresponding WhereLoop is
+  ** automatically order-distinct.
+  */
+
+  assert( pOrderBy!=0 );
+  if( nLoop && OptimizationDisabled(db, SQLITE_OrderByIdxJoin) ) return 0;
+
+  nOrderBy = pOrderBy->nExpr;
+  testcase( nOrderBy==BMS-1 );
+  if( nOrderBy>BMS-1 ) return 0;  /* Cannot optimize overly large ORDER BYs */
+  isOrderDistinct = 1;
+  obDone = MASKBIT(nOrderBy)-1;
+  orderDistinctMask = 0;
+  ready = 0;
+  eqOpMask = WO_EQ | WO_IS | WO_ISNULL;
+  if( wctrlFlags & WHERE_ORDERBY_LIMIT ) eqOpMask |= WO_IN;
+  for(iLoop=0; isOrderDistinct && obSat<obDone && iLoop<=nLoop; iLoop++){
+    if( iLoop>0 ) ready |= pLoop->maskSelf;
+    if( iLoop<nLoop ){
+      pLoop = pPath->aLoop[iLoop];
+      if( wctrlFlags & WHERE_ORDERBY_LIMIT ) continue;
+    }else{
+      pLoop = pLast;
+    }
+    if( pLoop->wsFlags & WHERE_VIRTUALTABLE ){
+      if( pLoop->u.vtab.isOrdered ) obSat = obDone;
+      break;
+    }
+    iCur = pWInfo->pTabList->a[pLoop->iTab].iCursor;
+
+    /* Mark off any ORDER BY term X that is a column in the table of
+    ** the current loop for which there is term in the WHERE
+    ** clause of the form X IS NULL or X=? that reference only outer
+    ** loops.
+    */
+    for(i=0; i<nOrderBy; i++){
+      if( MASKBIT(i) & obSat ) continue;
+      pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[i].pExpr);
+      if( pOBExpr->op!=TK_COLUMN ) continue;
+      if( pOBExpr->iTable!=iCur ) continue;
+      pTerm = sqlite3WhereFindTerm(&pWInfo->sWC, iCur, pOBExpr->iColumn,
+                       ~ready, eqOpMask, 0);
+      if( pTerm==0 ) continue;
+      if( pTerm->eOperator==WO_IN ){
+        /* IN terms are only valid for sorting in the ORDER BY LIMIT 
+        ** optimization, and then only if they are actually used
+        ** by the query plan */
+        assert( wctrlFlags & WHERE_ORDERBY_LIMIT );
+        for(j=0; j<pLoop->nLTerm && pTerm!=pLoop->aLTerm[j]; j++){}
+        if( j>=pLoop->nLTerm ) continue;
+      }
+      if( (pTerm->eOperator&(WO_EQ|WO_IS))!=0 && pOBExpr->iColumn>=0 ){
+        const char *z1, *z2;
+        pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr);
+        if( !pColl ) pColl = db->pDfltColl;
+        z1 = pColl->zName;
+        pColl = sqlite3ExprCollSeq(pWInfo->pParse, pTerm->pExpr);
+        if( !pColl ) pColl = db->pDfltColl;
+        z2 = pColl->zName;
+        if( sqlite3StrICmp(z1, z2)!=0 ) continue;
+        testcase( pTerm->pExpr->op==TK_IS );
+      }
+      obSat |= MASKBIT(i);
+    }
+
+    if( (pLoop->wsFlags & WHERE_ONEROW)==0 ){
+      if( pLoop->wsFlags & WHERE_IPK ){
+        pIndex = 0;
+        nKeyCol = 0;
+        nColumn = 1;
+      }else if( (pIndex = pLoop->u.btree.pIndex)==0 || pIndex->bUnordered ){
+        return 0;
+      }else{
+        nKeyCol = pIndex->nKeyCol;
+        nColumn = pIndex->nColumn;
+        assert( nColumn==nKeyCol+1 || !HasRowid(pIndex->pTable) );
+        assert( pIndex->aiColumn[nColumn-1]==XN_ROWID
+                          || !HasRowid(pIndex->pTable));
+        isOrderDistinct = IsUniqueIndex(pIndex);
+      }
+
+      /* Loop through all columns of the index and deal with the ones
+      ** that are not constrained by == or IN.
+      */
+      rev = revSet = 0;
+      distinctColumns = 0;
+      for(j=0; j<nColumn; j++){
+        u8 bOnce = 1; /* True to run the ORDER BY search loop */
+
+        assert( j>=pLoop->u.btree.nEq 
+            || (pLoop->aLTerm[j]==0)==(j<pLoop->nSkip)
+        );
+        if( j<pLoop->u.btree.nEq && j>=pLoop->nSkip ){
+          u16 eOp = pLoop->aLTerm[j]->eOperator;
+
+          /* Skip over == and IS and ISNULL terms.  (Also skip IN terms when
+          ** doing WHERE_ORDERBY_LIMIT processing). 
+          **
+          ** If the current term is a column of an ((?,?) IN (SELECT...)) 
+          ** expression for which the SELECT returns more than one column,
+          ** check that it is the only column used by this loop. Otherwise,
+          ** if it is one of two or more, none of the columns can be
+          ** considered to match an ORDER BY term.  */
+          if( (eOp & eqOpMask)!=0 ){
+            if( eOp & WO_ISNULL ){
+              testcase( isOrderDistinct );
+              isOrderDistinct = 0;
+            }
+            continue;  
+          }else if( ALWAYS(eOp & WO_IN) ){
+            /* ALWAYS() justification: eOp is an equality operator due to the
+            ** j<pLoop->u.btree.nEq constraint above.  Any equality other
+            ** than WO_IN is captured by the previous "if".  So this one
+            ** always has to be WO_IN. */
+            Expr *pX = pLoop->aLTerm[j]->pExpr;
+            for(i=j+1; i<pLoop->u.btree.nEq; i++){
+              if( pLoop->aLTerm[i]->pExpr==pX ){
+                assert( (pLoop->aLTerm[i]->eOperator & WO_IN) );
+                bOnce = 0;
+                break;
+              }
+            }
+          }
+        }
+
+        /* Get the column number in the table (iColumn) and sort order
+        ** (revIdx) for the j-th column of the index.
+        */
+        if( pIndex ){
+          iColumn = pIndex->aiColumn[j];
+          revIdx = pIndex->aSortOrder[j];
+          if( iColumn==pIndex->pTable->iPKey ) iColumn = -1;
+        }else{
+          iColumn = XN_ROWID;
+          revIdx = 0;
+        }
+
+        /* An unconstrained column that might be NULL means that this
+        ** WhereLoop is not well-ordered
+        */
+        if( isOrderDistinct
+         && iColumn>=0
+         && j>=pLoop->u.btree.nEq
+         && pIndex->pTable->aCol[iColumn].notNull==0
+        ){
+          isOrderDistinct = 0;
+        }
+
+        /* Find the ORDER BY term that corresponds to the j-th column
+        ** of the index and mark that ORDER BY term off 
+        */
+        isMatch = 0;
+        for(i=0; bOnce && i<nOrderBy; i++){
+          if( MASKBIT(i) & obSat ) continue;
+          pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[i].pExpr);
+          testcase( wctrlFlags & WHERE_GROUPBY );
+          testcase( wctrlFlags & WHERE_DISTINCTBY );
+          if( (wctrlFlags & (WHERE_GROUPBY|WHERE_DISTINCTBY))==0 ) bOnce = 0;
+          if( iColumn>=(-1) ){
+            if( pOBExpr->op!=TK_COLUMN ) continue;
+            if( pOBExpr->iTable!=iCur ) continue;
+            if( pOBExpr->iColumn!=iColumn ) continue;
+          }else{
+            if( sqlite3ExprCompare(pOBExpr,pIndex->aColExpr->a[j].pExpr,iCur) ){
+              continue;
+            }
+          }
+          if( iColumn>=0 ){
+            pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr);
+            if( !pColl ) pColl = db->pDfltColl;
+            if( sqlite3StrICmp(pColl->zName, pIndex->azColl[j])!=0 ) continue;
+          }
+          isMatch = 1;
+          break;
+        }
+        if( isMatch && (wctrlFlags & WHERE_GROUPBY)==0 ){
+          /* Make sure the sort order is compatible in an ORDER BY clause.
+          ** Sort order is irrelevant for a GROUP BY clause. */
+          if( revSet ){
+            if( (rev ^ revIdx)!=pOrderBy->a[i].sortOrder ) isMatch = 0;
+          }else{
+            rev = revIdx ^ pOrderBy->a[i].sortOrder;
+            if( rev ) *pRevMask |= MASKBIT(iLoop);
+            revSet = 1;
+          }
+        }
+        if( isMatch ){
+          if( iColumn==XN_ROWID ){
+            testcase( distinctColumns==0 );
+            distinctColumns = 1;
+          }
+          obSat |= MASKBIT(i);
+        }else{
+          /* No match found */
+          if( j==0 || j<nKeyCol ){
+            testcase( isOrderDistinct!=0 );
+            isOrderDistinct = 0;
+          }
+          break;
+        }
+      } /* end Loop over all index columns */
+      if( distinctColumns ){
+        testcase( isOrderDistinct==0 );
+        isOrderDistinct = 1;
+      }
+    } /* end-if not one-row */
+
+    /* Mark off any other ORDER BY terms that reference pLoop */
+    if( isOrderDistinct ){
+      orderDistinctMask |= pLoop->maskSelf;
+      for(i=0; i<nOrderBy; i++){
+        Expr *p;
+        Bitmask mTerm;
+        if( MASKBIT(i) & obSat ) continue;
+        p = pOrderBy->a[i].pExpr;
+        mTerm = sqlite3WhereExprUsage(&pWInfo->sMaskSet,p);
+        if( mTerm==0 && !sqlite3ExprIsConstant(p) ) continue;
+        if( (mTerm&~orderDistinctMask)==0 ){
+          obSat |= MASKBIT(i);
+        }
+      }
+    }
+  } /* End the loop over all WhereLoops from outer-most down to inner-most */
+  if( obSat==obDone ) return (i8)nOrderBy;
+  if( !isOrderDistinct ){
+    for(i=nOrderBy-1; i>0; i--){
+      Bitmask m = MASKBIT(i) - 1;
+      if( (obSat&m)==m ) return i;
+    }
+    return 0;
+  }
+  return -1;
+}
+
+
+/*
+** If the WHERE_GROUPBY flag is set in the mask passed to sqlite3WhereBegin(),
+** the planner assumes that the specified pOrderBy list is actually a GROUP
+** BY clause - and so any order that groups rows as required satisfies the
+** request.
+**
+** Normally, in this case it is not possible for the caller to determine
+** whether or not the rows are really being delivered in sorted order, or
+** just in some other order that provides the required grouping. However,
+** if the WHERE_SORTBYGROUP flag is also passed to sqlite3WhereBegin(), then
+** this function may be called on the returned WhereInfo object. It returns
+** true if the rows really will be sorted in the specified order, or false
+** otherwise.
+**
+** For example, assuming:
+**
+**   CREATE INDEX i1 ON t1(x, Y);
+**
+** then
+**
+**   SELECT * FROM t1 GROUP BY x,y ORDER BY x,y;   -- IsSorted()==1
+**   SELECT * FROM t1 GROUP BY y,x ORDER BY y,x;   -- IsSorted()==0
+*/
+SQLITE_PRIVATE int sqlite3WhereIsSorted(WhereInfo *pWInfo){
+  assert( pWInfo->wctrlFlags & WHERE_GROUPBY );
+  assert( pWInfo->wctrlFlags & WHERE_SORTBYGROUP );
+  return pWInfo->sorted;
+}
+
+#ifdef WHERETRACE_ENABLED
+/* For debugging use only: */
+static const char *wherePathName(WherePath *pPath, int nLoop, WhereLoop *pLast){
+  static char zName[65];
+  int i;
+  for(i=0; i<nLoop; i++){ zName[i] = pPath->aLoop[i]->cId; }
+  if( pLast ) zName[i++] = pLast->cId;
+  zName[i] = 0;
+  return zName;
+}
+#endif
+
+/*
+** Return the cost of sorting nRow rows, assuming that the keys have 
+** nOrderby columns and that the first nSorted columns are already in
+** order.
+*/
+static LogEst whereSortingCost(
+  WhereInfo *pWInfo,
+  LogEst nRow,
+  int nOrderBy,
+  int nSorted
+){
+  /* TUNING: Estimated cost of a full external sort, where N is 
+  ** the number of rows to sort is:
+  **
+  **   cost = (3.0 * N * log(N)).
+  ** 
+  ** Or, if the order-by clause has X terms but only the last Y 
+  ** terms are out of order, then block-sorting will reduce the 
+  ** sorting cost to:
+  **
+  **   cost = (3.0 * N * log(N)) * (Y/X)
+  **
+  ** The (Y/X) term is implemented using stack variable rScale
+  ** below.  */
+  LogEst rScale, rSortCost;
+  assert( nOrderBy>0 && 66==sqlite3LogEst(100) );
+  rScale = sqlite3LogEst((nOrderBy-nSorted)*100/nOrderBy) - 66;
+  rSortCost = nRow + rScale + 16;
+
+  /* Multiple by log(M) where M is the number of output rows.
+  ** Use the LIMIT for M if it is smaller */
+  if( (pWInfo->wctrlFlags & WHERE_USE_LIMIT)!=0 && pWInfo->iLimit<nRow ){
+    nRow = pWInfo->iLimit;
+  }
+  rSortCost += estLog(nRow);
+  return rSortCost;
+}
+
+/*
+** Given the list of WhereLoop objects at pWInfo->pLoops, this routine
+** attempts to find the lowest cost path that visits each WhereLoop
+** once.  This path is then loaded into the pWInfo->a[].pWLoop fields.
+**
+** Assume that the total number of output rows that will need to be sorted
+** will be nRowEst (in the 10*log2 representation).  Or, ignore sorting
+** costs if nRowEst==0.
+**
+** Return SQLITE_OK on success or SQLITE_NOMEM of a memory allocation
+** error occurs.
+*/
+static int wherePathSolver(WhereInfo *pWInfo, LogEst nRowEst){
+  int mxChoice;             /* Maximum number of simultaneous paths tracked */
+  int nLoop;                /* Number of terms in the join */
+  Parse *pParse;            /* Parsing context */
+  sqlite3 *db;              /* The database connection */
+  int iLoop;                /* Loop counter over the terms of the join */
+  int ii, jj;               /* Loop counters */
+  int mxI = 0;              /* Index of next entry to replace */
+  int nOrderBy;             /* Number of ORDER BY clause terms */
+  LogEst mxCost = 0;        /* Maximum cost of a set of paths */
+  LogEst mxUnsorted = 0;    /* Maximum unsorted cost of a set of path */
+  int nTo, nFrom;           /* Number of valid entries in aTo[] and aFrom[] */
+  WherePath *aFrom;         /* All nFrom paths at the previous level */
+  WherePath *aTo;           /* The nTo best paths at the current level */
+  WherePath *pFrom;         /* An element of aFrom[] that we are working on */
+  WherePath *pTo;           /* An element of aTo[] that we are working on */
+  WhereLoop *pWLoop;        /* One of the WhereLoop objects */
+  WhereLoop **pX;           /* Used to divy up the pSpace memory */
+  LogEst *aSortCost = 0;    /* Sorting and partial sorting costs */
+  char *pSpace;             /* Temporary memory used by this routine */
+  int nSpace;               /* Bytes of space allocated at pSpace */
+
+  pParse = pWInfo->pParse;
+  db = pParse->db;
+  nLoop = pWInfo->nLevel;
+  /* TUNING: For simple queries, only the best path is tracked.
+  ** For 2-way joins, the 5 best paths are followed.
+  ** For joins of 3 or more tables, track the 10 best paths */
+  mxChoice = (nLoop<=1) ? 1 : (nLoop==2 ? 5 : 10);
+  assert( nLoop<=pWInfo->pTabList->nSrc );
+  WHERETRACE(0x002, ("---- begin solver.  (nRowEst=%d)\n", nRowEst));
+
+  /* If nRowEst is zero and there is an ORDER BY clause, ignore it. In this
+  ** case the purpose of this call is to estimate the number of rows returned
+  ** by the overall query. Once this estimate has been obtained, the caller
+  ** will invoke this function a second time, passing the estimate as the
+  ** nRowEst parameter.  */
+  if( pWInfo->pOrderBy==0 || nRowEst==0 ){
+    nOrderBy = 0;
+  }else{
+    nOrderBy = pWInfo->pOrderBy->nExpr;
+  }
+
+  /* Allocate and initialize space for aTo, aFrom and aSortCost[] */
+  nSpace = (sizeof(WherePath)+sizeof(WhereLoop*)*nLoop)*mxChoice*2;
+  nSpace += sizeof(LogEst) * nOrderBy;
+  pSpace = sqlite3DbMallocRawNN(db, nSpace);
+  if( pSpace==0 ) return SQLITE_NOMEM_BKPT;
+  aTo = (WherePath*)pSpace;
+  aFrom = aTo+mxChoice;
+  memset(aFrom, 0, sizeof(aFrom[0]));
+  pX = (WhereLoop**)(aFrom+mxChoice);
+  for(ii=mxChoice*2, pFrom=aTo; ii>0; ii--, pFrom++, pX += nLoop){
+    pFrom->aLoop = pX;
+  }
+  if( nOrderBy ){
+    /* If there is an ORDER BY clause and it is not being ignored, set up
+    ** space for the aSortCost[] array. Each element of the aSortCost array
+    ** is either zero - meaning it has not yet been initialized - or the
+    ** cost of sorting nRowEst rows of data where the first X terms of
+    ** the ORDER BY clause are already in order, where X is the array 
+    ** index.  */
+    aSortCost = (LogEst*)pX;
+    memset(aSortCost, 0, sizeof(LogEst) * nOrderBy);
+  }
+  assert( aSortCost==0 || &pSpace[nSpace]==(char*)&aSortCost[nOrderBy] );
+  assert( aSortCost!=0 || &pSpace[nSpace]==(char*)pX );
+
+  /* Seed the search with a single WherePath containing zero WhereLoops.
+  **
+  ** TUNING: Do not let the number of iterations go above 28.  If the cost
+  ** of computing an automatic index is not paid back within the first 28
+  ** rows, then do not use the automatic index. */
+  aFrom[0].nRow = MIN(pParse->nQueryLoop, 48);  assert( 48==sqlite3LogEst(28) );
+  nFrom = 1;
+  assert( aFrom[0].isOrdered==0 );
+  if( nOrderBy ){
+    /* If nLoop is zero, then there are no FROM terms in the query. Since
+    ** in this case the query may return a maximum of one row, the results
+    ** are already in the requested order. Set isOrdered to nOrderBy to
+    ** indicate this. Or, if nLoop is greater than zero, set isOrdered to
+    ** -1, indicating that the result set may or may not be ordered, 
+    ** depending on the loops added to the current plan.  */
+    aFrom[0].isOrdered = nLoop>0 ? -1 : nOrderBy;
+  }
+
+  /* Compute successively longer WherePaths using the previous generation
+  ** of WherePaths as the basis for the next.  Keep track of the mxChoice
+  ** best paths at each generation */
+  for(iLoop=0; iLoop<nLoop; iLoop++){
+    nTo = 0;
+    for(ii=0, pFrom=aFrom; ii<nFrom; ii++, pFrom++){
+      for(pWLoop=pWInfo->pLoops; pWLoop; pWLoop=pWLoop->pNextLoop){
+        LogEst nOut;                      /* Rows visited by (pFrom+pWLoop) */
+        LogEst rCost;                     /* Cost of path (pFrom+pWLoop) */
+        LogEst rUnsorted;                 /* Unsorted cost of (pFrom+pWLoop) */
+        i8 isOrdered = pFrom->isOrdered;  /* isOrdered for (pFrom+pWLoop) */
+        Bitmask maskNew;                  /* Mask of src visited by (..) */
+        Bitmask revMask = 0;              /* Mask of rev-order loops for (..) */
+
+        if( (pWLoop->prereq & ~pFrom->maskLoop)!=0 ) continue;
+        if( (pWLoop->maskSelf & pFrom->maskLoop)!=0 ) continue;
+        if( (pWLoop->wsFlags & WHERE_AUTO_INDEX)!=0 && pFrom->nRow<10 ){
+          /* Do not use an automatic index if the this loop is expected
+          ** to run less than 2 times. */
+          assert( 10==sqlite3LogEst(2) );
+          continue;
+        }
+        /* At this point, pWLoop is a candidate to be the next loop. 
+        ** Compute its cost */
+        rUnsorted = sqlite3LogEstAdd(pWLoop->rSetup,pWLoop->rRun + pFrom->nRow);
+        rUnsorted = sqlite3LogEstAdd(rUnsorted, pFrom->rUnsorted);
+        nOut = pFrom->nRow + pWLoop->nOut;
+        maskNew = pFrom->maskLoop | pWLoop->maskSelf;
+        if( isOrdered<0 ){
+          isOrdered = wherePathSatisfiesOrderBy(pWInfo,
+                       pWInfo->pOrderBy, pFrom, pWInfo->wctrlFlags,
+                       iLoop, pWLoop, &revMask);
+        }else{
+          revMask = pFrom->revLoop;
+        }
+        if( isOrdered>=0 && isOrdered<nOrderBy ){
+          if( aSortCost[isOrdered]==0 ){
+            aSortCost[isOrdered] = whereSortingCost(
+                pWInfo, nRowEst, nOrderBy, isOrdered
+            );
+          }
+          rCost = sqlite3LogEstAdd(rUnsorted, aSortCost[isOrdered]);
+
+          WHERETRACE(0x002,
+              ("---- sort cost=%-3d (%d/%d) increases cost %3d to %-3d\n",
+               aSortCost[isOrdered], (nOrderBy-isOrdered), nOrderBy, 
+               rUnsorted, rCost));
+        }else{
+          rCost = rUnsorted;
+        }
+
+        /* Check to see if pWLoop should be added to the set of
+        ** mxChoice best-so-far paths.
+        **
+        ** First look for an existing path among best-so-far paths
+        ** that covers the same set of loops and has the same isOrdered
+        ** setting as the current path candidate.
+        **
+        ** The term "((pTo->isOrdered^isOrdered)&0x80)==0" is equivalent
+        ** to (pTo->isOrdered==(-1))==(isOrdered==(-1))" for the range
+        ** of legal values for isOrdered, -1..64.
+        */
+        for(jj=0, pTo=aTo; jj<nTo; jj++, pTo++){
+          if( pTo->maskLoop==maskNew
+           && ((pTo->isOrdered^isOrdered)&0x80)==0
+          ){
+            testcase( jj==nTo-1 );
+            break;
+          }
+        }
+        if( jj>=nTo ){
+          /* None of the existing best-so-far paths match the candidate. */
+          if( nTo>=mxChoice
+           && (rCost>mxCost || (rCost==mxCost && rUnsorted>=mxUnsorted))
+          ){
+            /* The current candidate is no better than any of the mxChoice
+            ** paths currently in the best-so-far buffer.  So discard
+            ** this candidate as not viable. */
+#ifdef WHERETRACE_ENABLED /* 0x4 */
+            if( sqlite3WhereTrace&0x4 ){
+              sqlite3DebugPrintf("Skip   %s cost=%-3d,%3d order=%c\n",
+                  wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
+                  isOrdered>=0 ? isOrdered+'0' : '?');
+            }
+#endif
+            continue;
+          }
+          /* If we reach this points it means that the new candidate path
+          ** needs to be added to the set of best-so-far paths. */
+          if( nTo<mxChoice ){
+            /* Increase the size of the aTo set by one */
+            jj = nTo++;
+          }else{
+            /* New path replaces the prior worst to keep count below mxChoice */
+            jj = mxI;
+          }
+          pTo = &aTo[jj];
+#ifdef WHERETRACE_ENABLED /* 0x4 */
+          if( sqlite3WhereTrace&0x4 ){
+            sqlite3DebugPrintf("New    %s cost=%-3d,%3d order=%c\n",
+                wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
+                isOrdered>=0 ? isOrdered+'0' : '?');
+          }
+#endif
+        }else{
+          /* Control reaches here if best-so-far path pTo=aTo[jj] covers the
+          ** same set of loops and has the sam isOrdered setting as the
+          ** candidate path.  Check to see if the candidate should replace
+          ** pTo or if the candidate should be skipped */
+          if( pTo->rCost<rCost || (pTo->rCost==rCost && pTo->nRow<=nOut) ){
+#ifdef WHERETRACE_ENABLED /* 0x4 */
+            if( sqlite3WhereTrace&0x4 ){
+              sqlite3DebugPrintf(
+                  "Skip   %s cost=%-3d,%3d order=%c",
+                  wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
+                  isOrdered>=0 ? isOrdered+'0' : '?');
+              sqlite3DebugPrintf("   vs %s cost=%-3d,%d order=%c\n",
+                  wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
+                  pTo->isOrdered>=0 ? pTo->isOrdered+'0' : '?');
+            }
+#endif
+            /* Discard the candidate path from further consideration */
+            testcase( pTo->rCost==rCost );
+            continue;
+          }
+          testcase( pTo->rCost==rCost+1 );
+          /* Control reaches here if the candidate path is better than the
+          ** pTo path.  Replace pTo with the candidate. */
+#ifdef WHERETRACE_ENABLED /* 0x4 */
+          if( sqlite3WhereTrace&0x4 ){
+            sqlite3DebugPrintf(
+                "Update %s cost=%-3d,%3d order=%c",
+                wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
+                isOrdered>=0 ? isOrdered+'0' : '?');
+            sqlite3DebugPrintf("  was %s cost=%-3d,%3d order=%c\n",
+                wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
+                pTo->isOrdered>=0 ? pTo->isOrdered+'0' : '?');
+          }
+#endif
+        }
+        /* pWLoop is a winner.  Add it to the set of best so far */
+        pTo->maskLoop = pFrom->maskLoop | pWLoop->maskSelf;
+        pTo->revLoop = revMask;
+        pTo->nRow = nOut;
+        pTo->rCost = rCost;
+        pTo->rUnsorted = rUnsorted;
+        pTo->isOrdered = isOrdered;
+        memcpy(pTo->aLoop, pFrom->aLoop, sizeof(WhereLoop*)*iLoop);
+        pTo->aLoop[iLoop] = pWLoop;
+        if( nTo>=mxChoice ){
+          mxI = 0;
+          mxCost = aTo[0].rCost;
+          mxUnsorted = aTo[0].nRow;
+          for(jj=1, pTo=&aTo[1]; jj<mxChoice; jj++, pTo++){
+            if( pTo->rCost>mxCost 
+             || (pTo->rCost==mxCost && pTo->rUnsorted>mxUnsorted) 
+            ){
+              mxCost = pTo->rCost;
+              mxUnsorted = pTo->rUnsorted;
+              mxI = jj;
+            }
+          }
+        }
+      }
+    }
+
+#ifdef WHERETRACE_ENABLED  /* >=2 */
+    if( sqlite3WhereTrace & 0x02 ){
+      sqlite3DebugPrintf("---- after round %d ----\n", iLoop);
+      for(ii=0, pTo=aTo; ii<nTo; ii++, pTo++){
+        sqlite3DebugPrintf(" %s cost=%-3d nrow=%-3d order=%c",
+           wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
+           pTo->isOrdered>=0 ? (pTo->isOrdered+'0') : '?');
+        if( pTo->isOrdered>0 ){
+          sqlite3DebugPrintf(" rev=0x%llx\n", pTo->revLoop);
+        }else{
+          sqlite3DebugPrintf("\n");
+        }
+      }
+    }
+#endif
+
+    /* Swap the roles of aFrom and aTo for the next generation */
+    pFrom = aTo;
+    aTo = aFrom;
+    aFrom = pFrom;
+    nFrom = nTo;
+  }
+
+  if( nFrom==0 ){
+    sqlite3ErrorMsg(pParse, "no query solution");
+    sqlite3DbFree(db, pSpace);
+    return SQLITE_ERROR;
+  }
+  
+  /* Find the lowest cost path.  pFrom will be left pointing to that path */
+  pFrom = aFrom;
+  for(ii=1; ii<nFrom; ii++){
+    if( pFrom->rCost>aFrom[ii].rCost ) pFrom = &aFrom[ii];
+  }
+  assert( pWInfo->nLevel==nLoop );
+  /* Load the lowest cost path into pWInfo */
+  for(iLoop=0; iLoop<nLoop; iLoop++){
+    WhereLevel *pLevel = pWInfo->a + iLoop;
+    pLevel->pWLoop = pWLoop = pFrom->aLoop[iLoop];
+    pLevel->iFrom = pWLoop->iTab;
+    pLevel->iTabCur = pWInfo->pTabList->a[pLevel->iFrom].iCursor;
+  }
+  if( (pWInfo->wctrlFlags & WHERE_WANT_DISTINCT)!=0
+   && (pWInfo->wctrlFlags & WHERE_DISTINCTBY)==0
+   && pWInfo->eDistinct==WHERE_DISTINCT_NOOP
+   && nRowEst
+  ){
+    Bitmask notUsed;
+    int rc = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pDistinctSet, pFrom,
+                 WHERE_DISTINCTBY, nLoop-1, pFrom->aLoop[nLoop-1], &notUsed);
+    if( rc==pWInfo->pDistinctSet->nExpr ){
+      pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
+    }
+  }
+  if( pWInfo->pOrderBy ){
+    if( pWInfo->wctrlFlags & WHERE_DISTINCTBY ){
+      if( pFrom->isOrdered==pWInfo->pOrderBy->nExpr ){
+        pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
+      }
+    }else{
+      pWInfo->nOBSat = pFrom->isOrdered;
+      pWInfo->revMask = pFrom->revLoop;
+      if( pWInfo->nOBSat<=0 ){
+        pWInfo->nOBSat = 0;
+        if( nLoop>0 ){
+          u32 wsFlags = pFrom->aLoop[nLoop-1]->wsFlags;
+          if( (wsFlags & WHERE_ONEROW)==0 
+           && (wsFlags&(WHERE_IPK|WHERE_COLUMN_IN))!=(WHERE_IPK|WHERE_COLUMN_IN)
+          ){
+            Bitmask m = 0;
+            int rc = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pOrderBy, pFrom,
+                      WHERE_ORDERBY_LIMIT, nLoop-1, pFrom->aLoop[nLoop-1], &m);
+            testcase( wsFlags & WHERE_IPK );
+            testcase( wsFlags & WHERE_COLUMN_IN );
+            if( rc==pWInfo->pOrderBy->nExpr ){
+              pWInfo->bOrderedInnerLoop = 1;
+              pWInfo->revMask = m;
+            }
+          }
+        }
+      }
+    }
+    if( (pWInfo->wctrlFlags & WHERE_SORTBYGROUP)
+        && pWInfo->nOBSat==pWInfo->pOrderBy->nExpr && nLoop>0
+    ){
+      Bitmask revMask = 0;
+      int nOrder = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pOrderBy, 
+          pFrom, 0, nLoop-1, pFrom->aLoop[nLoop-1], &revMask
+      );
+      assert( pWInfo->sorted==0 );
+      if( nOrder==pWInfo->pOrderBy->nExpr ){
+        pWInfo->sorted = 1;
+        pWInfo->revMask = revMask;
+      }
+    }
+  }
+
+
+  pWInfo->nRowOut = pFrom->nRow;
+
+  /* Free temporary memory and return success */
+  sqlite3DbFree(db, pSpace);
+  return SQLITE_OK;
+}
+
+/*
+** Most queries use only a single table (they are not joins) and have
+** simple == constraints against indexed fields.  This routine attempts
+** to plan those simple cases using much less ceremony than the
+** general-purpose query planner, and thereby yield faster sqlite3_prepare()
+** times for the common case.
+**
+** Return non-zero on success, if this query can be handled by this
+** no-frills query planner.  Return zero if this query needs the 
+** general-purpose query planner.
+*/
+static int whereShortCut(WhereLoopBuilder *pBuilder){
+  WhereInfo *pWInfo;
+  struct SrcList_item *pItem;
+  WhereClause *pWC;
+  WhereTerm *pTerm;
+  WhereLoop *pLoop;
+  int iCur;
+  int j;
+  Table *pTab;
+  Index *pIdx;
+
+  pWInfo = pBuilder->pWInfo;
+  if( pWInfo->wctrlFlags & WHERE_OR_SUBCLAUSE ) return 0;
+  assert( pWInfo->pTabList->nSrc>=1 );
+  pItem = pWInfo->pTabList->a;
+  pTab = pItem->pTab;
+  if( IsVirtual(pTab) ) return 0;
+  if( pItem->fg.isIndexedBy ) return 0;
+  iCur = pItem->iCursor;
+  pWC = &pWInfo->sWC;
+  pLoop = pBuilder->pNew;
+  pLoop->wsFlags = 0;
+  pLoop->nSkip = 0;
+  pTerm = sqlite3WhereFindTerm(pWC, iCur, -1, 0, WO_EQ|WO_IS, 0);
+  if( pTerm ){
+    testcase( pTerm->eOperator & WO_IS );
+    pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_IPK|WHERE_ONEROW;
+    pLoop->aLTerm[0] = pTerm;
+    pLoop->nLTerm = 1;
+    pLoop->u.btree.nEq = 1;
+    /* TUNING: Cost of a rowid lookup is 10 */
+    pLoop->rRun = 33;  /* 33==sqlite3LogEst(10) */
+  }else{
+    for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+      int opMask;
+      assert( pLoop->aLTermSpace==pLoop->aLTerm );
+      if( !IsUniqueIndex(pIdx)
+       || pIdx->pPartIdxWhere!=0 
+       || pIdx->nKeyCol>ArraySize(pLoop->aLTermSpace) 
+      ) continue;
+      opMask = pIdx->uniqNotNull ? (WO_EQ|WO_IS) : WO_EQ;
+      for(j=0; j<pIdx->nKeyCol; j++){
+        pTerm = sqlite3WhereFindTerm(pWC, iCur, j, 0, opMask, pIdx);
+        if( pTerm==0 ) break;
+        testcase( pTerm->eOperator & WO_IS );
+        pLoop->aLTerm[j] = pTerm;
+      }
+      if( j!=pIdx->nKeyCol ) continue;
+      pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_ONEROW|WHERE_INDEXED;
+      if( pIdx->isCovering || (pItem->colUsed & ~columnsInIndex(pIdx))==0 ){
+        pLoop->wsFlags |= WHERE_IDX_ONLY;
+      }
+      pLoop->nLTerm = j;
+      pLoop->u.btree.nEq = j;
+      pLoop->u.btree.pIndex = pIdx;
+      /* TUNING: Cost of a unique index lookup is 15 */
+      pLoop->rRun = 39;  /* 39==sqlite3LogEst(15) */
+      break;
+    }
+  }
+  if( pLoop->wsFlags ){
+    pLoop->nOut = (LogEst)1;
+    pWInfo->a[0].pWLoop = pLoop;
+    pLoop->maskSelf = sqlite3WhereGetMask(&pWInfo->sMaskSet, iCur);
+    pWInfo->a[0].iTabCur = iCur;
+    pWInfo->nRowOut = 1;
+    if( pWInfo->pOrderBy ) pWInfo->nOBSat =  pWInfo->pOrderBy->nExpr;
+    if( pWInfo->wctrlFlags & WHERE_WANT_DISTINCT ){
+      pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
+    }
+#ifdef SQLITE_DEBUG
+    pLoop->cId = '0';
+#endif
+    return 1;
+  }
+  return 0;
+}
+
+/*
+** Generate the beginning of the loop used for WHERE clause processing.
+** The return value is a pointer to an opaque structure that contains
+** information needed to terminate the loop.  Later, the calling routine
+** should invoke sqlite3WhereEnd() with the return value of this function
+** in order to complete the WHERE clause processing.
+**
+** If an error occurs, this routine returns NULL.
+**
+** The basic idea is to do a nested loop, one loop for each table in
+** the FROM clause of a select.  (INSERT and UPDATE statements are the
+** same as a SELECT with only a single table in the FROM clause.)  For
+** example, if the SQL is this:
+**
+**       SELECT * FROM t1, t2, t3 WHERE ...;
+**
+** Then the code generated is conceptually like the following:
+**
+**      foreach row1 in t1 do       \    Code generated
+**        foreach row2 in t2 do      |-- by sqlite3WhereBegin()
+**          foreach row3 in t3 do   /
+**            ...
+**          end                     \    Code generated
+**        end                        |-- by sqlite3WhereEnd()
+**      end                         /
+**
+** Note that the loops might not be nested in the order in which they
+** appear in the FROM clause if a different order is better able to make
+** use of indices.  Note also that when the IN operator appears in
+** the WHERE clause, it might result in additional nested loops for
+** scanning through all values on the right-hand side of the IN.
+**
+** There are Btree cursors associated with each table.  t1 uses cursor
+** number pTabList->a[0].iCursor.  t2 uses the cursor pTabList->a[1].iCursor.
+** And so forth.  This routine generates code to open those VDBE cursors
+** and sqlite3WhereEnd() generates the code to close them.
+**
+** The code that sqlite3WhereBegin() generates leaves the cursors named
+** in pTabList pointing at their appropriate entries.  The [...] code
+** can use OP_Column and OP_Rowid opcodes on these cursors to extract
+** data from the various tables of the loop.
+**
+** If the WHERE clause is empty, the foreach loops must each scan their
+** entire tables.  Thus a three-way join is an O(N^3) operation.  But if
+** the tables have indices and there are terms in the WHERE clause that
+** refer to those indices, a complete table scan can be avoided and the
+** code will run much faster.  Most of the work of this routine is checking
+** to see if there are indices that can be used to speed up the loop.
+**
+** Terms of the WHERE clause are also used to limit which rows actually
+** make it to the "..." in the middle of the loop.  After each "foreach",
+** terms of the WHERE clause that use only terms in that loop and outer
+** loops are evaluated and if false a jump is made around all subsequent
+** inner loops (or around the "..." if the test occurs within the inner-
+** most loop)
+**
+** OUTER JOINS
+**
+** An outer join of tables t1 and t2 is conceptally coded as follows:
+**
+**    foreach row1 in t1 do
+**      flag = 0
+**      foreach row2 in t2 do
+**        start:
+**          ...
+**          flag = 1
+**      end
+**      if flag==0 then
+**        move the row2 cursor to a null row
+**        goto start
+**      fi
+**    end
+**
+** ORDER BY CLAUSE PROCESSING
+**
+** pOrderBy is a pointer to the ORDER BY clause (or the GROUP BY clause
+** if the WHERE_GROUPBY flag is set in wctrlFlags) of a SELECT statement
+** if there is one.  If there is no ORDER BY clause or if this routine
+** is called from an UPDATE or DELETE statement, then pOrderBy is NULL.
+**
+** The iIdxCur parameter is the cursor number of an index.  If 
+** WHERE_OR_SUBCLAUSE is set, iIdxCur is the cursor number of an index
+** to use for OR clause processing.  The WHERE clause should use this
+** specific cursor.  If WHERE_ONEPASS_DESIRED is set, then iIdxCur is
+** the first cursor in an array of cursors for all indices.  iIdxCur should
+** be used to compute the appropriate cursor depending on which index is
+** used.
+*/
+SQLITE_PRIVATE WhereInfo *sqlite3WhereBegin(
+  Parse *pParse,          /* The parser context */
+  SrcList *pTabList,      /* FROM clause: A list of all tables to be scanned */
+  Expr *pWhere,           /* The WHERE clause */
+  ExprList *pOrderBy,     /* An ORDER BY (or GROUP BY) clause, or NULL */
+  ExprList *pDistinctSet, /* Try not to output two rows that duplicate these */
+  u16 wctrlFlags,         /* The WHERE_* flags defined in sqliteInt.h */
+  int iAuxArg             /* If WHERE_OR_SUBCLAUSE is set, index cursor number
+                          ** If WHERE_USE_LIMIT, then the limit amount */
+){
+  int nByteWInfo;            /* Num. bytes allocated for WhereInfo struct */
+  int nTabList;              /* Number of elements in pTabList */
+  WhereInfo *pWInfo;         /* Will become the return value of this function */
+  Vdbe *v = pParse->pVdbe;   /* The virtual database engine */
+  Bitmask notReady;          /* Cursors that are not yet positioned */
+  WhereLoopBuilder sWLB;     /* The WhereLoop builder */
+  WhereMaskSet *pMaskSet;    /* The expression mask set */
+  WhereLevel *pLevel;        /* A single level in pWInfo->a[] */
+  WhereLoop *pLoop;          /* Pointer to a single WhereLoop object */
+  int ii;                    /* Loop counter */
+  sqlite3 *db;               /* Database connection */
+  int rc;                    /* Return code */
+  u8 bFordelete = 0;         /* OPFLAG_FORDELETE or zero, as appropriate */
+
+  assert( (wctrlFlags & WHERE_ONEPASS_MULTIROW)==0 || (
+        (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 
+     && (wctrlFlags & WHERE_OR_SUBCLAUSE)==0 
+  ));
+
+  /* Only one of WHERE_OR_SUBCLAUSE or WHERE_USE_LIMIT */
+  assert( (wctrlFlags & WHERE_OR_SUBCLAUSE)==0
+            || (wctrlFlags & WHERE_USE_LIMIT)==0 );
+
+  /* Variable initialization */
+  db = pParse->db;
+  memset(&sWLB, 0, sizeof(sWLB));
+
+  /* An ORDER/GROUP BY clause of more than 63 terms cannot be optimized */
+  testcase( pOrderBy && pOrderBy->nExpr==BMS-1 );
+  if( pOrderBy && pOrderBy->nExpr>=BMS ) pOrderBy = 0;
+  sWLB.pOrderBy = pOrderBy;
+
+  /* Disable the DISTINCT optimization if SQLITE_DistinctOpt is set via
+  ** sqlite3_test_ctrl(SQLITE_TESTCTRL_OPTIMIZATIONS,...) */
+  if( OptimizationDisabled(db, SQLITE_DistinctOpt) ){
+    wctrlFlags &= ~WHERE_WANT_DISTINCT;
+  }
+
+  /* The number of tables in the FROM clause is limited by the number of
+  ** bits in a Bitmask 
+  */
+  testcase( pTabList->nSrc==BMS );
+  if( pTabList->nSrc>BMS ){
+    sqlite3ErrorMsg(pParse, "at most %d tables in a join", BMS);
+    return 0;
+  }
+
+  /* This function normally generates a nested loop for all tables in 
+  ** pTabList.  But if the WHERE_OR_SUBCLAUSE flag is set, then we should
+  ** only generate code for the first table in pTabList and assume that
+  ** any cursors associated with subsequent tables are uninitialized.
+  */
+  nTabList = (wctrlFlags & WHERE_OR_SUBCLAUSE) ? 1 : pTabList->nSrc;
+
+  /* Allocate and initialize the WhereInfo structure that will become the
+  ** return value. A single allocation is used to store the WhereInfo
+  ** struct, the contents of WhereInfo.a[], the WhereClause structure
+  ** and the WhereMaskSet structure. Since WhereClause contains an 8-byte
+  ** field (type Bitmask) it must be aligned on an 8-byte boundary on
+  ** some architectures. Hence the ROUND8() below.
+  */
+  nByteWInfo = ROUND8(sizeof(WhereInfo)+(nTabList-1)*sizeof(WhereLevel));
+  pWInfo = sqlite3DbMallocRawNN(db, nByteWInfo + sizeof(WhereLoop));
+  if( db->mallocFailed ){
+    sqlite3DbFree(db, pWInfo);
+    pWInfo = 0;
+    goto whereBeginError;
+  }
+  pWInfo->pParse = pParse;
+  pWInfo->pTabList = pTabList;
+  pWInfo->pOrderBy = pOrderBy;
+  pWInfo->pDistinctSet = pDistinctSet;
+  pWInfo->aiCurOnePass[0] = pWInfo->aiCurOnePass[1] = -1;
+  pWInfo->nLevel = nTabList;
+  pWInfo->iBreak = pWInfo->iContinue = sqlite3VdbeMakeLabel(v);
+  pWInfo->wctrlFlags = wctrlFlags;
+  pWInfo->iLimit = iAuxArg;
+  pWInfo->savedNQueryLoop = pParse->nQueryLoop;
+  memset(&pWInfo->nOBSat, 0, 
+         offsetof(WhereInfo,sWC) - offsetof(WhereInfo,nOBSat));
+  memset(&pWInfo->a[0], 0, sizeof(WhereLoop)+nTabList*sizeof(WhereLevel));
+  assert( pWInfo->eOnePass==ONEPASS_OFF );  /* ONEPASS defaults to OFF */
+  pMaskSet = &pWInfo->sMaskSet;
+  sWLB.pWInfo = pWInfo;
+  sWLB.pWC = &pWInfo->sWC;
+  sWLB.pNew = (WhereLoop*)(((char*)pWInfo)+nByteWInfo);
+  assert( EIGHT_BYTE_ALIGNMENT(sWLB.pNew) );
+  whereLoopInit(sWLB.pNew);
+#ifdef SQLITE_DEBUG
+  sWLB.pNew->cId = '*';
+#endif
+
+  /* Split the WHERE clause into separate subexpressions where each
+  ** subexpression is separated by an AND operator.
+  */
+  initMaskSet(pMaskSet);
+  sqlite3WhereClauseInit(&pWInfo->sWC, pWInfo);
+  sqlite3WhereSplit(&pWInfo->sWC, pWhere, TK_AND);
+    
+  /* Special case: a WHERE clause that is constant.  Evaluate the
+  ** expression and either jump over all of the code or fall thru.
+  */
+  for(ii=0; ii<sWLB.pWC->nTerm; ii++){
+    if( nTabList==0 || sqlite3ExprIsConstantNotJoin(sWLB.pWC->a[ii].pExpr) ){
+      sqlite3ExprIfFalse(pParse, sWLB.pWC->a[ii].pExpr, pWInfo->iBreak,
+                         SQLITE_JUMPIFNULL);
+      sWLB.pWC->a[ii].wtFlags |= TERM_CODED;
+    }
+  }
+
+  /* Special case: No FROM clause
+  */
+  if( nTabList==0 ){
+    if( pOrderBy ) pWInfo->nOBSat = pOrderBy->nExpr;
+    if( wctrlFlags & WHERE_WANT_DISTINCT ){
+      pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
+    }
+  }
+
+  /* Assign a bit from the bitmask to every term in the FROM clause.
+  **
+  ** The N-th term of the FROM clause is assigned a bitmask of 1<<N.
+  **
+  ** The rule of the previous sentence ensures thta if X is the bitmask for
+  ** a table T, then X-1 is the bitmask for all other tables to the left of T.
+  ** Knowing the bitmask for all tables to the left of a left join is
+  ** important.  Ticket #3015.
+  **
+  ** Note that bitmasks are created for all pTabList->nSrc tables in
+  ** pTabList, not just the first nTabList tables.  nTabList is normally
+  ** equal to pTabList->nSrc but might be shortened to 1 if the
+  ** WHERE_OR_SUBCLAUSE flag is set.
+  */
+  for(ii=0; ii<pTabList->nSrc; ii++){
+    createMask(pMaskSet, pTabList->a[ii].iCursor);
+    sqlite3WhereTabFuncArgs(pParse, &pTabList->a[ii], &pWInfo->sWC);
+  }
+#ifdef SQLITE_DEBUG
+  for(ii=0; ii<pTabList->nSrc; ii++){
+    Bitmask m = sqlite3WhereGetMask(pMaskSet, pTabList->a[ii].iCursor);
+    assert( m==MASKBIT(ii) );
+  }
+#endif
+
+  /* Analyze all of the subexpressions. */
+  sqlite3WhereExprAnalyze(pTabList, &pWInfo->sWC);
+  if( db->mallocFailed ) goto whereBeginError;
+
+  if( wctrlFlags & WHERE_WANT_DISTINCT ){
+    if( isDistinctRedundant(pParse, pTabList, &pWInfo->sWC, pDistinctSet) ){
+      /* The DISTINCT marking is pointless.  Ignore it. */
+      pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
+    }else if( pOrderBy==0 ){
+      /* Try to ORDER BY the result set to make distinct processing easier */
+      pWInfo->wctrlFlags |= WHERE_DISTINCTBY;
+      pWInfo->pOrderBy = pDistinctSet;
+    }
+  }
+
+  /* Construct the WhereLoop objects */
+#if defined(WHERETRACE_ENABLED)
+  if( sqlite3WhereTrace & 0xffff ){
+    sqlite3DebugPrintf("*** Optimizer Start *** (wctrlFlags: 0x%x",wctrlFlags);
+    if( wctrlFlags & WHERE_USE_LIMIT ){
+      sqlite3DebugPrintf(", limit: %d", iAuxArg);
+    }
+    sqlite3DebugPrintf(")\n");
+  }
+  if( sqlite3WhereTrace & 0x100 ){ /* Display all terms of the WHERE clause */
+    sqlite3WhereClausePrint(sWLB.pWC);
+  }
+#endif
+
+  if( nTabList!=1 || whereShortCut(&sWLB)==0 ){
+    rc = whereLoopAddAll(&sWLB);
+    if( rc ) goto whereBeginError;
+  
+#ifdef WHERETRACE_ENABLED
+    if( sqlite3WhereTrace ){    /* Display all of the WhereLoop objects */
+      WhereLoop *p;
+      int i;
+      static const char zLabel[] = "0123456789abcdefghijklmnopqrstuvwyxz"
+                                             "ABCDEFGHIJKLMNOPQRSTUVWYXZ";
+      for(p=pWInfo->pLoops, i=0; p; p=p->pNextLoop, i++){
+        p->cId = zLabel[i%sizeof(zLabel)];
+        whereLoopPrint(p, sWLB.pWC);
+      }
+    }
+#endif
+  
+    wherePathSolver(pWInfo, 0);
+    if( db->mallocFailed ) goto whereBeginError;
+    if( pWInfo->pOrderBy ){
+       wherePathSolver(pWInfo, pWInfo->nRowOut+1);
+       if( db->mallocFailed ) goto whereBeginError;
+    }
+  }
+  if( pWInfo->pOrderBy==0 && (db->flags & SQLITE_ReverseOrder)!=0 ){
+     pWInfo->revMask = ALLBITS;
+  }
+  if( pParse->nErr || NEVER(db->mallocFailed) ){
+    goto whereBeginError;
+  }
+#ifdef WHERETRACE_ENABLED
+  if( sqlite3WhereTrace ){
+    sqlite3DebugPrintf("---- Solution nRow=%d", pWInfo->nRowOut);
+    if( pWInfo->nOBSat>0 ){
+      sqlite3DebugPrintf(" ORDERBY=%d,0x%llx", pWInfo->nOBSat, pWInfo->revMask);
+    }
+    switch( pWInfo->eDistinct ){
+      case WHERE_DISTINCT_UNIQUE: {
+        sqlite3DebugPrintf("  DISTINCT=unique");
+        break;
+      }
+      case WHERE_DISTINCT_ORDERED: {
+        sqlite3DebugPrintf("  DISTINCT=ordered");
+        break;
+      }
+      case WHERE_DISTINCT_UNORDERED: {
+        sqlite3DebugPrintf("  DISTINCT=unordered");
+        break;
+      }
+    }
+    sqlite3DebugPrintf("\n");
+    for(ii=0; ii<pWInfo->nLevel; ii++){
+      whereLoopPrint(pWInfo->a[ii].pWLoop, sWLB.pWC);
+    }
+  }
+#endif
+  /* Attempt to omit tables from the join that do not effect the result */
+  if( pWInfo->nLevel>=2
+   && pDistinctSet!=0
+   && OptimizationEnabled(db, SQLITE_OmitNoopJoin)
+  ){
+    Bitmask tabUsed = sqlite3WhereExprListUsage(pMaskSet, pDistinctSet);
+    if( sWLB.pOrderBy ){
+      tabUsed |= sqlite3WhereExprListUsage(pMaskSet, sWLB.pOrderBy);
+    }
+    while( pWInfo->nLevel>=2 ){
+      WhereTerm *pTerm, *pEnd;
+      pLoop = pWInfo->a[pWInfo->nLevel-1].pWLoop;
+      if( (pWInfo->pTabList->a[pLoop->iTab].fg.jointype & JT_LEFT)==0 ) break;
+      if( (wctrlFlags & WHERE_WANT_DISTINCT)==0
+       && (pLoop->wsFlags & WHERE_ONEROW)==0
+      ){
+        break;
+      }
+      if( (tabUsed & pLoop->maskSelf)!=0 ) break;
+      pEnd = sWLB.pWC->a + sWLB.pWC->nTerm;
+      for(pTerm=sWLB.pWC->a; pTerm<pEnd; pTerm++){
+        if( (pTerm->prereqAll & pLoop->maskSelf)!=0
+         && !ExprHasProperty(pTerm->pExpr, EP_FromJoin)
+        ){
+          break;
+        }
+      }
+      if( pTerm<pEnd ) break;
+      WHERETRACE(0xffff, ("-> drop loop %c not used\n", pLoop->cId));
+      pWInfo->nLevel--;
+      nTabList--;
+    }
+  }
+  WHERETRACE(0xffff,("*** Optimizer Finished ***\n"));
+  pWInfo->pParse->nQueryLoop += pWInfo->nRowOut;
+
+  /* If the caller is an UPDATE or DELETE statement that is requesting
+  ** to use a one-pass algorithm, determine if this is appropriate.
+  */
+  assert( (wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || pWInfo->nLevel==1 );
+  if( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 ){
+    int wsFlags = pWInfo->a[0].pWLoop->wsFlags;
+    int bOnerow = (wsFlags & WHERE_ONEROW)!=0;
+    if( bOnerow
+     || ((wctrlFlags & WHERE_ONEPASS_MULTIROW)!=0
+           && 0==(wsFlags & WHERE_VIRTUALTABLE))
+    ){
+      pWInfo->eOnePass = bOnerow ? ONEPASS_SINGLE : ONEPASS_MULTI;
+      if( HasRowid(pTabList->a[0].pTab) && (wsFlags & WHERE_IDX_ONLY) ){
+        if( wctrlFlags & WHERE_ONEPASS_MULTIROW ){
+          bFordelete = OPFLAG_FORDELETE;
+        }
+        pWInfo->a[0].pWLoop->wsFlags = (wsFlags & ~WHERE_IDX_ONLY);
+      }
+    }
+  }
+
+  /* Open all tables in the pTabList and any indices selected for
+  ** searching those tables.
+  */
+  for(ii=0, pLevel=pWInfo->a; ii<nTabList; ii++, pLevel++){
+    Table *pTab;     /* Table to open */
+    int iDb;         /* Index of database containing table/index */
+    struct SrcList_item *pTabItem;
+
+    pTabItem = &pTabList->a[pLevel->iFrom];
+    pTab = pTabItem->pTab;
+    iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+    pLoop = pLevel->pWLoop;
+    if( (pTab->tabFlags & TF_Ephemeral)!=0 || pTab->pSelect ){
+      /* Do nothing */
+    }else
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    if( (pLoop->wsFlags & WHERE_VIRTUALTABLE)!=0 ){
+      const char *pVTab = (const char *)sqlite3GetVTable(db, pTab);
+      int iCur = pTabItem->iCursor;
+      sqlite3VdbeAddOp4(v, OP_VOpen, iCur, 0, 0, pVTab, P4_VTAB);
+    }else if( IsVirtual(pTab) ){
+      /* noop */
+    }else
+#endif
+    if( (pLoop->wsFlags & WHERE_IDX_ONLY)==0
+         && (wctrlFlags & WHERE_OR_SUBCLAUSE)==0 ){
+      int op = OP_OpenRead;
+      if( pWInfo->eOnePass!=ONEPASS_OFF ){
+        op = OP_OpenWrite;
+        pWInfo->aiCurOnePass[0] = pTabItem->iCursor;
+      };
+      sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, op);
+      assert( pTabItem->iCursor==pLevel->iTabCur );
+      testcase( pWInfo->eOnePass==ONEPASS_OFF && pTab->nCol==BMS-1 );
+      testcase( pWInfo->eOnePass==ONEPASS_OFF && pTab->nCol==BMS );
+      if( pWInfo->eOnePass==ONEPASS_OFF && pTab->nCol<BMS && HasRowid(pTab) ){
+        Bitmask b = pTabItem->colUsed;
+        int n = 0;
+        for(; b; b=b>>1, n++){}
+        sqlite3VdbeChangeP4(v, -1, SQLITE_INT_TO_PTR(n), P4_INT32);
+        assert( n<=pTab->nCol );
+      }
+#ifdef SQLITE_ENABLE_CURSOR_HINTS
+      if( pLoop->u.btree.pIndex!=0 ){
+        sqlite3VdbeChangeP5(v, OPFLAG_SEEKEQ|bFordelete);
+      }else
+#endif
+      {
+        sqlite3VdbeChangeP5(v, bFordelete);
+      }
+#ifdef SQLITE_ENABLE_COLUMN_USED_MASK
+      sqlite3VdbeAddOp4Dup8(v, OP_ColumnsUsed, pTabItem->iCursor, 0, 0,
+                            (const u8*)&pTabItem->colUsed, P4_INT64);
+#endif
+    }else{
+      sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
+    }
+    if( pLoop->wsFlags & WHERE_INDEXED ){
+      Index *pIx = pLoop->u.btree.pIndex;
+      int iIndexCur;
+      int op = OP_OpenRead;
+      /* iAuxArg is always set if to a positive value if ONEPASS is possible */
+      assert( iAuxArg!=0 || (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0 );
+      if( !HasRowid(pTab) && IsPrimaryKeyIndex(pIx)
+       && (wctrlFlags & WHERE_OR_SUBCLAUSE)!=0
+      ){
+        /* This is one term of an OR-optimization using the PRIMARY KEY of a
+        ** WITHOUT ROWID table.  No need for a separate index */
+        iIndexCur = pLevel->iTabCur;
+        op = 0;
+      }else if( pWInfo->eOnePass!=ONEPASS_OFF ){
+        Index *pJ = pTabItem->pTab->pIndex;
+        iIndexCur = iAuxArg;
+        assert( wctrlFlags & WHERE_ONEPASS_DESIRED );
+        while( ALWAYS(pJ) && pJ!=pIx ){
+          iIndexCur++;
+          pJ = pJ->pNext;
+        }
+        op = OP_OpenWrite;
+        pWInfo->aiCurOnePass[1] = iIndexCur;
+      }else if( iAuxArg && (wctrlFlags & WHERE_OR_SUBCLAUSE)!=0 ){
+        iIndexCur = iAuxArg;
+        op = OP_ReopenIdx;
+      }else{
+        iIndexCur = pParse->nTab++;
+      }
+      pLevel->iIdxCur = iIndexCur;
+      assert( pIx->pSchema==pTab->pSchema );
+      assert( iIndexCur>=0 );
+      if( op ){
+        sqlite3VdbeAddOp3(v, op, iIndexCur, pIx->tnum, iDb);
+        sqlite3VdbeSetP4KeyInfo(pParse, pIx);
+        if( (pLoop->wsFlags & WHERE_CONSTRAINT)!=0
+         && (pLoop->wsFlags & (WHERE_COLUMN_RANGE|WHERE_SKIPSCAN))==0
+         && (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)==0
+        ){
+          sqlite3VdbeChangeP5(v, OPFLAG_SEEKEQ); /* Hint to COMDB2 */
+        }
+        VdbeComment((v, "%s", pIx->zName));
+#ifdef SQLITE_ENABLE_COLUMN_USED_MASK
+        {
+          u64 colUsed = 0;
+          int ii, jj;
+          for(ii=0; ii<pIx->nColumn; ii++){
+            jj = pIx->aiColumn[ii];
+            if( jj<0 ) continue;
+            if( jj>63 ) jj = 63;
+            if( (pTabItem->colUsed & MASKBIT(jj))==0 ) continue;
+            colUsed |= ((u64)1)<<(ii<63 ? ii : 63);
+          }
+          sqlite3VdbeAddOp4Dup8(v, OP_ColumnsUsed, iIndexCur, 0, 0,
+                                (u8*)&colUsed, P4_INT64);
+        }
+#endif /* SQLITE_ENABLE_COLUMN_USED_MASK */
+      }
+    }
+    if( iDb>=0 ) sqlite3CodeVerifySchema(pParse, iDb);
+  }
+  pWInfo->iTop = sqlite3VdbeCurrentAddr(v);
+  if( db->mallocFailed ) goto whereBeginError;
+
+  /* Generate the code to do the search.  Each iteration of the for
+  ** loop below generates code for a single nested loop of the VM
+  ** program.
+  */
+  notReady = ~(Bitmask)0;
+  for(ii=0; ii<nTabList; ii++){
+    int addrExplain;
+    int wsFlags;
+    pLevel = &pWInfo->a[ii];
+    wsFlags = pLevel->pWLoop->wsFlags;
+#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
+    if( (pLevel->pWLoop->wsFlags & WHERE_AUTO_INDEX)!=0 ){
+      constructAutomaticIndex(pParse, &pWInfo->sWC,
+                &pTabList->a[pLevel->iFrom], notReady, pLevel);
+      if( db->mallocFailed ) goto whereBeginError;
+    }
+#endif
+    addrExplain = sqlite3WhereExplainOneScan(
+        pParse, pTabList, pLevel, ii, pLevel->iFrom, wctrlFlags
+    );
+    pLevel->addrBody = sqlite3VdbeCurrentAddr(v);
+    notReady = sqlite3WhereCodeOneLoopStart(pWInfo, ii, notReady);
+    pWInfo->iContinue = pLevel->addrCont;
+    if( (wsFlags&WHERE_MULTI_OR)==0 && (wctrlFlags&WHERE_OR_SUBCLAUSE)==0 ){
+      sqlite3WhereAddScanStatus(v, pTabList, pLevel, addrExplain);
+    }
+  }
+
+  /* Done. */
+  VdbeModuleComment((v, "Begin WHERE-core"));
+  return pWInfo;
+
+  /* Jump here if malloc fails */
+whereBeginError:
+  if( pWInfo ){
+    pParse->nQueryLoop = pWInfo->savedNQueryLoop;
+    whereInfoFree(db, pWInfo);
+  }
+  return 0;
+}
+
+/*
+** Generate the end of the WHERE loop.  See comments on 
+** sqlite3WhereBegin() for additional information.
+*/
+SQLITE_PRIVATE void sqlite3WhereEnd(WhereInfo *pWInfo){
+  Parse *pParse = pWInfo->pParse;
+  Vdbe *v = pParse->pVdbe;
+  int i;
+  WhereLevel *pLevel;
+  WhereLoop *pLoop;
+  SrcList *pTabList = pWInfo->pTabList;
+  sqlite3 *db = pParse->db;
+
+  /* Generate loop termination code.
+  */
+  VdbeModuleComment((v, "End WHERE-core"));
+  sqlite3ExprCacheClear(pParse);
+  for(i=pWInfo->nLevel-1; i>=0; i--){
+    int addr;
+    pLevel = &pWInfo->a[i];
+    pLoop = pLevel->pWLoop;
+    sqlite3VdbeResolveLabel(v, pLevel->addrCont);
+    if( pLevel->op!=OP_Noop ){
+      sqlite3VdbeAddOp3(v, pLevel->op, pLevel->p1, pLevel->p2, pLevel->p3);
+      sqlite3VdbeChangeP5(v, pLevel->p5);
+      VdbeCoverage(v);
+      VdbeCoverageIf(v, pLevel->op==OP_Next);
+      VdbeCoverageIf(v, pLevel->op==OP_Prev);
+      VdbeCoverageIf(v, pLevel->op==OP_VNext);
+    }
+    if( pLoop->wsFlags & WHERE_IN_ABLE && pLevel->u.in.nIn>0 ){
+      struct InLoop *pIn;
+      int j;
+      sqlite3VdbeResolveLabel(v, pLevel->addrNxt);
+      for(j=pLevel->u.in.nIn, pIn=&pLevel->u.in.aInLoop[j-1]; j>0; j--, pIn--){
+        sqlite3VdbeJumpHere(v, pIn->addrInTop+1);
+        if( pIn->eEndLoopOp!=OP_Noop ){
+          sqlite3VdbeAddOp2(v, pIn->eEndLoopOp, pIn->iCur, pIn->addrInTop);
+          VdbeCoverage(v);
+          VdbeCoverageIf(v, pIn->eEndLoopOp==OP_PrevIfOpen);
+          VdbeCoverageIf(v, pIn->eEndLoopOp==OP_NextIfOpen);
+        }
+        sqlite3VdbeJumpHere(v, pIn->addrInTop-1);
+      }
+    }
+    sqlite3VdbeResolveLabel(v, pLevel->addrBrk);
+    if( pLevel->addrSkip ){
+      sqlite3VdbeGoto(v, pLevel->addrSkip);
+      VdbeComment((v, "next skip-scan on %s", pLoop->u.btree.pIndex->zName));
+      sqlite3VdbeJumpHere(v, pLevel->addrSkip);
+      sqlite3VdbeJumpHere(v, pLevel->addrSkip-2);
+    }
+#ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
+    if( pLevel->addrLikeRep ){
+      sqlite3VdbeAddOp2(v, OP_DecrJumpZero, (int)(pLevel->iLikeRepCntr>>1),
+                        pLevel->addrLikeRep);
+      VdbeCoverage(v);
+    }
+#endif
+    if( pLevel->iLeftJoin ){
+      int ws = pLoop->wsFlags;
+      addr = sqlite3VdbeAddOp1(v, OP_IfPos, pLevel->iLeftJoin); VdbeCoverage(v);
+      assert( (ws & WHERE_IDX_ONLY)==0 || (ws & WHERE_INDEXED)!=0 );
+      if( (ws & WHERE_IDX_ONLY)==0 ){
+        sqlite3VdbeAddOp1(v, OP_NullRow, pTabList->a[i].iCursor);
+      }
+      if( (ws & WHERE_INDEXED) 
+       || ((ws & WHERE_MULTI_OR) && pLevel->u.pCovidx) 
+      ){
+        sqlite3VdbeAddOp1(v, OP_NullRow, pLevel->iIdxCur);
+      }
+      if( pLevel->op==OP_Return ){
+        sqlite3VdbeAddOp2(v, OP_Gosub, pLevel->p1, pLevel->addrFirst);
+      }else{
+        sqlite3VdbeGoto(v, pLevel->addrFirst);
+      }
+      sqlite3VdbeJumpHere(v, addr);
+    }
+    VdbeModuleComment((v, "End WHERE-loop%d: %s", i,
+                     pWInfo->pTabList->a[pLevel->iFrom].pTab->zName));
+  }
+
+  /* The "break" point is here, just past the end of the outer loop.
+  ** Set it.
+  */
+  sqlite3VdbeResolveLabel(v, pWInfo->iBreak);
+
+  assert( pWInfo->nLevel<=pTabList->nSrc );
+  for(i=0, pLevel=pWInfo->a; i<pWInfo->nLevel; i++, pLevel++){
+    int k, last;
+    VdbeOp *pOp;
+    Index *pIdx = 0;
+    struct SrcList_item *pTabItem = &pTabList->a[pLevel->iFrom];
+    Table *pTab = pTabItem->pTab;
+    assert( pTab!=0 );
+    pLoop = pLevel->pWLoop;
+
+    /* For a co-routine, change all OP_Column references to the table of
+    ** the co-routine into OP_Copy of result contained in a register.
+    ** OP_Rowid becomes OP_Null.
+    */
+    if( pTabItem->fg.viaCoroutine && !db->mallocFailed ){
+      translateColumnToCopy(v, pLevel->addrBody, pLevel->iTabCur,
+                            pTabItem->regResult, 0);
+      continue;
+    }
+
+    /* Close all of the cursors that were opened by sqlite3WhereBegin.
+    ** Except, do not close cursors that will be reused by the OR optimization
+    ** (WHERE_OR_SUBCLAUSE).  And do not close the OP_OpenWrite cursors
+    ** created for the ONEPASS optimization.
+    */
+    if( (pTab->tabFlags & TF_Ephemeral)==0
+     && pTab->pSelect==0
+     && (pWInfo->wctrlFlags & WHERE_OR_SUBCLAUSE)==0
+    ){
+      int ws = pLoop->wsFlags;
+      if( pWInfo->eOnePass==ONEPASS_OFF && (ws & WHERE_IDX_ONLY)==0 ){
+        sqlite3VdbeAddOp1(v, OP_Close, pTabItem->iCursor);
+      }
+      if( (ws & WHERE_INDEXED)!=0
+       && (ws & (WHERE_IPK|WHERE_AUTO_INDEX))==0 
+       && pLevel->iIdxCur!=pWInfo->aiCurOnePass[1]
+      ){
+        sqlite3VdbeAddOp1(v, OP_Close, pLevel->iIdxCur);
+      }
+    }
+
+    /* If this scan uses an index, make VDBE code substitutions to read data
+    ** from the index instead of from the table where possible.  In some cases
+    ** this optimization prevents the table from ever being read, which can
+    ** yield a significant performance boost.
+    ** 
+    ** Calls to the code generator in between sqlite3WhereBegin and
+    ** sqlite3WhereEnd will have created code that references the table
+    ** directly.  This loop scans all that code looking for opcodes
+    ** that reference the table and converts them into opcodes that
+    ** reference the index.
+    */
+    if( pLoop->wsFlags & (WHERE_INDEXED|WHERE_IDX_ONLY) ){
+      pIdx = pLoop->u.btree.pIndex;
+    }else if( pLoop->wsFlags & WHERE_MULTI_OR ){
+      pIdx = pLevel->u.pCovidx;
+    }
+    if( pIdx
+     && (pWInfo->eOnePass==ONEPASS_OFF || !HasRowid(pIdx->pTable))
+     && !db->mallocFailed
+    ){
+      last = sqlite3VdbeCurrentAddr(v);
+      k = pLevel->addrBody;
+      pOp = sqlite3VdbeGetOp(v, k);
+      for(; k<last; k++, pOp++){
+        if( pOp->p1!=pLevel->iTabCur ) continue;
+        if( pOp->opcode==OP_Column ){
+          int x = pOp->p2;
+          assert( pIdx->pTable==pTab );
+          if( !HasRowid(pTab) ){
+            Index *pPk = sqlite3PrimaryKeyIndex(pTab);
+            x = pPk->aiColumn[x];
+            assert( x>=0 );
+          }
+          x = sqlite3ColumnOfIndex(pIdx, x);
+          if( x>=0 ){
+            pOp->p2 = x;
+            pOp->p1 = pLevel->iIdxCur;
+          }
+          assert( (pLoop->wsFlags & WHERE_IDX_ONLY)==0 || x>=0 );
+        }else if( pOp->opcode==OP_Rowid ){
+          pOp->p1 = pLevel->iIdxCur;
+          pOp->opcode = OP_IdxRowid;
+        }
+      }
+    }
+  }
+
+  /* Final cleanup
+  */
+  pParse->nQueryLoop = pWInfo->savedNQueryLoop;
+  whereInfoFree(db, pWInfo);
+  return;
+}
+
+/************** End of where.c ***********************************************/
+/************** Begin file parse.c *******************************************/
+/*
+** 2000-05-29
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** Driver template for the LEMON parser generator.
+**
+** The "lemon" program processes an LALR(1) input grammar file, then uses
+** this template to construct a parser.  The "lemon" program inserts text
+** at each "%%" line.  Also, any "P-a-r-s-e" identifer prefix (without the
+** interstitial "-" characters) contained in this template is changed into
+** the value of the %name directive from the grammar.  Otherwise, the content
+** of this template is copied straight through into the generate parser
+** source file.
+**
+** The following is the concatenation of all %include directives from the
+** input grammar file:
+*/
+/* #include <stdio.h> */
+/************ Begin %include sections from the grammar ************************/
+
+/* #include "sqliteInt.h" */
+
+/*
+** Disable all error recovery processing in the parser push-down
+** automaton.
+*/
+#define YYNOERRORRECOVERY 1
+
+/*
+** Make yytestcase() the same as testcase()
+*/
+#define yytestcase(X) testcase(X)
+
+/*
+** Indicate that sqlite3ParserFree() will never be called with a null
+** pointer.
+*/
+#define YYPARSEFREENEVERNULL 1
+
+/*
+** Alternative datatype for the argument to the malloc() routine passed
+** into sqlite3ParserAlloc().  The default is size_t.
+*/
+#define YYMALLOCARGTYPE  u64
+
+/*
+** An instance of this structure holds information about the
+** LIMIT clause of a SELECT statement.
+*/
+struct LimitVal {
+  Expr *pLimit;    /* The LIMIT expression.  NULL if there is no limit */
+  Expr *pOffset;   /* The OFFSET expression.  NULL if there is none */
+};
+
+/*
+** An instance of the following structure describes the event of a
+** TRIGGER.  "a" is the event type, one of TK_UPDATE, TK_INSERT,
+** TK_DELETE, or TK_INSTEAD.  If the event is of the form
+**
+**      UPDATE ON (a,b,c)
+**
+** Then the "b" IdList records the list "a,b,c".
+*/
+struct TrigEvent { int a; IdList * b; };
+
+/*
+** Disable lookaside memory allocation for objects that might be
+** shared across database connections.
+*/
+static void disableLookaside(Parse *pParse){
+  pParse->disableLookaside++;
+  pParse->db->lookaside.bDisable++;
+}
+
+
+  /*
+  ** For a compound SELECT statement, make sure p->pPrior->pNext==p for
+  ** all elements in the list.  And make sure list length does not exceed
+  ** SQLITE_LIMIT_COMPOUND_SELECT.
+  */
+  static void parserDoubleLinkSelect(Parse *pParse, Select *p){
+    if( p->pPrior ){
+      Select *pNext = 0, *pLoop;
+      int mxSelect, cnt = 0;
+      for(pLoop=p; pLoop; pNext=pLoop, pLoop=pLoop->pPrior, cnt++){
+        pLoop->pNext = pNext;
+        pLoop->selFlags |= SF_Compound;
+      }
+      if( (p->selFlags & SF_MultiValue)==0 && 
+        (mxSelect = pParse->db->aLimit[SQLITE_LIMIT_COMPOUND_SELECT])>0 &&
+        cnt>mxSelect
+      ){
+        sqlite3ErrorMsg(pParse, "too many terms in compound SELECT");
+      }
+    }
+  }
+
+  /* This is a utility routine used to set the ExprSpan.zStart and
+  ** ExprSpan.zEnd values of pOut so that the span covers the complete
+  ** range of text beginning with pStart and going to the end of pEnd.
+  */
+  static void spanSet(ExprSpan *pOut, Token *pStart, Token *pEnd){
+    pOut->zStart = pStart->z;
+    pOut->zEnd = &pEnd->z[pEnd->n];
+  }
+
+  /* Construct a new Expr object from a single identifier.  Use the
+  ** new Expr to populate pOut.  Set the span of pOut to be the identifier
+  ** that created the expression.
+  */
+  static void spanExpr(ExprSpan *pOut, Parse *pParse, int op, Token t){
+    Expr *p = sqlite3DbMallocRawNN(pParse->db, sizeof(Expr)+t.n+1);
+    if( p ){
+      memset(p, 0, sizeof(Expr));
+      p->op = (u8)op;
+      p->flags = EP_Leaf;
+      p->iAgg = -1;
+      p->u.zToken = (char*)&p[1];
+      memcpy(p->u.zToken, t.z, t.n);
+      p->u.zToken[t.n] = 0;
+      if( sqlite3Isquote(p->u.zToken[0]) ){
+        if( p->u.zToken[0]=='"' ) p->flags |= EP_DblQuoted;
+        sqlite3Dequote(p->u.zToken);
+      }
+#if SQLITE_MAX_EXPR_DEPTH>0
+      p->nHeight = 1;
+#endif  
+    }
+    pOut->pExpr = p;
+    pOut->zStart = t.z;
+    pOut->zEnd = &t.z[t.n];
+  }
+
+  /* This routine constructs a binary expression node out of two ExprSpan
+  ** objects and uses the result to populate a new ExprSpan object.
+  */
+  static void spanBinaryExpr(
+    Parse *pParse,      /* The parsing context.  Errors accumulate here */
+    int op,             /* The binary operation */
+    ExprSpan *pLeft,    /* The left operand, and output */
+    ExprSpan *pRight    /* The right operand */
+  ){
+    pLeft->pExpr = sqlite3PExpr(pParse, op, pLeft->pExpr, pRight->pExpr, 0);
+    pLeft->zEnd = pRight->zEnd;
+  }
+
+  /* If doNot is true, then add a TK_NOT Expr-node wrapper around the
+  ** outside of *ppExpr.
+  */
+  static void exprNot(Parse *pParse, int doNot, ExprSpan *pSpan){
+    if( doNot ){
+      pSpan->pExpr = sqlite3PExpr(pParse, TK_NOT, pSpan->pExpr, 0, 0);
+    }
+  }
+
+  /* Construct an expression node for a unary postfix operator
+  */
+  static void spanUnaryPostfix(
+    Parse *pParse,         /* Parsing context to record errors */
+    int op,                /* The operator */
+    ExprSpan *pOperand,    /* The operand, and output */
+    Token *pPostOp         /* The operand token for setting the span */
+  ){
+    pOperand->pExpr = sqlite3PExpr(pParse, op, pOperand->pExpr, 0, 0);
+    pOperand->zEnd = &pPostOp->z[pPostOp->n];
+  }                           
+
+  /* A routine to convert a binary TK_IS or TK_ISNOT expression into a
+  ** unary TK_ISNULL or TK_NOTNULL expression. */
+  static void binaryToUnaryIfNull(Parse *pParse, Expr *pY, Expr *pA, int op){
+    sqlite3 *db = pParse->db;
+    if( pA && pY && pY->op==TK_NULL ){
+      pA->op = (u8)op;
+      sqlite3ExprDelete(db, pA->pRight);
+      pA->pRight = 0;
+    }
+  }
+
+  /* Construct an expression node for a unary prefix operator
+  */
+  static void spanUnaryPrefix(
+    ExprSpan *pOut,        /* Write the new expression node here */
+    Parse *pParse,         /* Parsing context to record errors */
+    int op,                /* The operator */
+    ExprSpan *pOperand,    /* The operand */
+    Token *pPreOp         /* The operand token for setting the span */
+  ){
+    pOut->zStart = pPreOp->z;
+    pOut->pExpr = sqlite3PExpr(pParse, op, pOperand->pExpr, 0, 0);
+    pOut->zEnd = pOperand->zEnd;
+  }
+
+  /* Add a single new term to an ExprList that is used to store a
+  ** list of identifiers.  Report an error if the ID list contains
+  ** a COLLATE clause or an ASC or DESC keyword, except ignore the
+  ** error while parsing a legacy schema.
+  */
+  static ExprList *parserAddExprIdListTerm(
+    Parse *pParse,
+    ExprList *pPrior,
+    Token *pIdToken,
+    int hasCollate,
+    int sortOrder
+  ){
+    ExprList *p = sqlite3ExprListAppend(pParse, pPrior, 0);
+    if( (hasCollate || sortOrder!=SQLITE_SO_UNDEFINED)
+        && pParse->db->init.busy==0
+    ){
+      sqlite3ErrorMsg(pParse, "syntax error after column name \"%.*s\"",
+                         pIdToken->n, pIdToken->z);
+    }
+    sqlite3ExprListSetName(pParse, p, pIdToken, 1);
+    return p;
+  }
+/**************** End of %include directives **********************************/
+/* These constants specify the various numeric values for terminal symbols
+** in a format understandable to "makeheaders".  This section is blank unless
+** "lemon" is run with the "-m" command-line option.
+***************** Begin makeheaders token definitions *************************/
+/**************** End makeheaders token definitions ***************************/
+
+/* The next sections is a series of control #defines.
+** various aspects of the generated parser.
+**    YYCODETYPE         is the data type used to store the integer codes
+**                       that represent terminal and non-terminal symbols.
+**                       "unsigned char" is used if there are fewer than
+**                       256 symbols.  Larger types otherwise.
+**    YYNOCODE           is a number of type YYCODETYPE that is not used for
+**                       any terminal or nonterminal symbol.
+**    YYFALLBACK         If defined, this indicates that one or more tokens
+**                       (also known as: "terminal symbols") have fall-back
+**                       values which should be used if the original symbol
+**                       would not parse.  This permits keywords to sometimes
+**                       be used as identifiers, for example.
+**    YYACTIONTYPE       is the data type used for "action codes" - numbers
+**                       that indicate what to do in response to the next
+**                       token.
+**    sqlite3ParserTOKENTYPE     is the data type used for minor type for terminal
+**                       symbols.  Background: A "minor type" is a semantic
+**                       value associated with a terminal or non-terminal
+**                       symbols.  For example, for an "ID" terminal symbol,
+**                       the minor type might be the name of the identifier.
+**                       Each non-terminal can have a different minor type.
+**                       Terminal symbols all have the same minor type, though.
+**                       This macros defines the minor type for terminal 
+**                       symbols.
+**    YYMINORTYPE        is the data type used for all minor types.
+**                       This is typically a union of many types, one of
+**                       which is sqlite3ParserTOKENTYPE.  The entry in the union
+**                       for terminal symbols is called "yy0".
+**    YYSTACKDEPTH       is the maximum depth of the parser's stack.  If
+**                       zero the stack is dynamically sized using realloc()
+**    sqlite3ParserARG_SDECL     A static variable declaration for the %extra_argument
+**    sqlite3ParserARG_PDECL     A parameter declaration for the %extra_argument
+**    sqlite3ParserARG_STORE     Code to store %extra_argument into yypParser
+**    sqlite3ParserARG_FETCH     Code to extract %extra_argument from yypParser
+**    YYERRORSYMBOL      is the code number of the error symbol.  If not
+**                       defined, then do no error processing.
+**    YYNSTATE           the combined number of states.
+**    YYNRULE            the number of rules in the grammar
+**    YY_MAX_SHIFT       Maximum value for shift actions
+**    YY_MIN_SHIFTREDUCE Minimum value for shift-reduce actions
+**    YY_MAX_SHIFTREDUCE Maximum value for shift-reduce actions
+**    YY_MIN_REDUCE      Maximum value for reduce actions
+**    YY_ERROR_ACTION    The yy_action[] code for syntax error
+**    YY_ACCEPT_ACTION   The yy_action[] code for accept
+**    YY_NO_ACTION       The yy_action[] code for no-op
+*/
+#ifndef INTERFACE
+# define INTERFACE 1
+#endif
+/************* Begin control #defines *****************************************/
+#define YYCODETYPE unsigned char
+#define YYNOCODE 252
+#define YYACTIONTYPE unsigned short int
+#define YYWILDCARD 96
+#define sqlite3ParserTOKENTYPE Token
+typedef union {
+  int yyinit;
+  sqlite3ParserTOKENTYPE yy0;
+  Expr* yy72;
+  TriggerStep* yy145;
+  ExprList* yy148;
+  SrcList* yy185;
+  ExprSpan yy190;
+  int yy194;
+  Select* yy243;
+  IdList* yy254;
+  With* yy285;
+  struct TrigEvent yy332;
+  struct LimitVal yy354;
+  struct {int value; int mask;} yy497;
+} YYMINORTYPE;
+#ifndef YYSTACKDEPTH
+#define YYSTACKDEPTH 100
+#endif
+#define sqlite3ParserARG_SDECL Parse *pParse;
+#define sqlite3ParserARG_PDECL ,Parse *pParse
+#define sqlite3ParserARG_FETCH Parse *pParse = yypParser->pParse
+#define sqlite3ParserARG_STORE yypParser->pParse = pParse
+#define YYFALLBACK 1
+#define YYNSTATE             456
+#define YYNRULE              332
+#define YY_MAX_SHIFT         455
+#define YY_MIN_SHIFTREDUCE   668
+#define YY_MAX_SHIFTREDUCE   999
+#define YY_MIN_REDUCE        1000
+#define YY_MAX_REDUCE        1331
+#define YY_ERROR_ACTION      1332
+#define YY_ACCEPT_ACTION     1333
+#define YY_NO_ACTION         1334
+/************* End control #defines *******************************************/
+
+/* Define the yytestcase() macro to be a no-op if is not already defined
+** otherwise.
+**
+** Applications can choose to define yytestcase() in the %include section
+** to a macro that can assist in verifying code coverage.  For production
+** code the yytestcase() macro should be turned off.  But it is useful
+** for testing.
+*/
+#ifndef yytestcase
+# define yytestcase(X)
+#endif
+
+
+/* Next are the tables used to determine what action to take based on the
+** current state and lookahead token.  These tables are used to implement
+** functions that take a state number and lookahead value and return an
+** action integer.  
+**
+** Suppose the action integer is N.  Then the action is determined as
+** follows
+**
+**   0 <= N <= YY_MAX_SHIFT             Shift N.  That is, push the lookahead
+**                                      token onto the stack and goto state N.
+**
+**   N between YY_MIN_SHIFTREDUCE       Shift to an arbitrary state then
+**     and YY_MAX_SHIFTREDUCE           reduce by rule N-YY_MIN_SHIFTREDUCE.
+**
+**   N between YY_MIN_REDUCE            Reduce by rule N-YY_MIN_REDUCE
+**     and YY_MAX_REDUCE
+**
+**   N == YY_ERROR_ACTION               A syntax error has occurred.
+**
+**   N == YY_ACCEPT_ACTION              The parser accepts its input.
+**
+**   N == YY_NO_ACTION                  No such action.  Denotes unused
+**                                      slots in the yy_action[] table.
+**
+** The action table is constructed as a single large table named yy_action[].
+** Given state S and lookahead X, the action is computed as either:
+**
+**    (A)   N = yy_action[ yy_shift_ofst[S] + X ]
+**    (B)   N = yy_default[S]
+**
+** The (A) formula is preferred.  The B formula is used instead if:
+**    (1)  The yy_shift_ofst[S]+X value is out of range, or
+**    (2)  yy_lookahead[yy_shift_ofst[S]+X] is not equal to X, or
+**    (3)  yy_shift_ofst[S] equal YY_SHIFT_USE_DFLT.
+** (Implementation note: YY_SHIFT_USE_DFLT is chosen so that
+** YY_SHIFT_USE_DFLT+X will be out of range for all possible lookaheads X.
+** Hence only tests (1) and (2) need to be evaluated.)
+**
+** The formulas above are for computing the action when the lookahead is
+** a terminal symbol.  If the lookahead is a non-terminal (as occurs after
+** a reduce action) then the yy_reduce_ofst[] array is used in place of
+** the yy_shift_ofst[] array and YY_REDUCE_USE_DFLT is used in place of
+** YY_SHIFT_USE_DFLT.
+**
+** The following are the tables generated in this section:
+**
+**  yy_action[]        A single table containing all actions.
+**  yy_lookahead[]     A table containing the lookahead for each entry in
+**                     yy_action.  Used to detect hash collisions.
+**  yy_shift_ofst[]    For each state, the offset into yy_action for
+**                     shifting terminals.
+**  yy_reduce_ofst[]   For each state, the offset into yy_action for
+**                     shifting non-terminals after a reduce.
+**  yy_default[]       Default action for each state.
+**
+*********** Begin parsing tables **********************************************/
+#define YY_ACTTAB_COUNT (1567)
+static const YYACTIONTYPE yy_action[] = {
+ /*     0 */   325,  832,  351,  825,    5,  203,  203,  819,   99,  100,
+ /*    10 */    90,  842,  842,  854,  857,  846,  846,   97,   97,   98,
+ /*    20 */    98,   98,   98,  301,   96,   96,   96,   96,   95,   95,
+ /*    30 */    94,   94,   94,   93,  351,  325,  977,  977,  824,  824,
+ /*    40 */   826,  947,  354,   99,  100,   90,  842,  842,  854,  857,
+ /*    50 */   846,  846,   97,   97,   98,   98,   98,   98,  338,   96,
+ /*    60 */    96,   96,   96,   95,   95,   94,   94,   94,   93,  351,
+ /*    70 */    95,   95,   94,   94,   94,   93,  351,  791,  977,  977,
+ /*    80 */   325,   94,   94,   94,   93,  351,  792,   75,   99,  100,
+ /*    90 */    90,  842,  842,  854,  857,  846,  846,   97,   97,   98,
+ /*   100 */    98,   98,   98,  450,   96,   96,   96,   96,   95,   95,
+ /*   110 */    94,   94,   94,   93,  351, 1333,  155,  155,    2,  325,
+ /*   120 */   275,  146,  132,   52,   52,   93,  351,   99,  100,   90,
+ /*   130 */   842,  842,  854,  857,  846,  846,   97,   97,   98,   98,
+ /*   140 */    98,   98,  101,   96,   96,   96,   96,   95,   95,   94,
+ /*   150 */    94,   94,   93,  351,  958,  958,  325,  268,  428,  413,
+ /*   160 */   411,   61,  752,  752,   99,  100,   90,  842,  842,  854,
+ /*   170 */   857,  846,  846,   97,   97,   98,   98,   98,   98,   60,
+ /*   180 */    96,   96,   96,   96,   95,   95,   94,   94,   94,   93,
+ /*   190 */   351,  325,  270,  329,  273,  277,  959,  960,  250,   99,
+ /*   200 */   100,   90,  842,  842,  854,  857,  846,  846,   97,   97,
+ /*   210 */    98,   98,   98,   98,  301,   96,   96,   96,   96,   95,
+ /*   220 */    95,   94,   94,   94,   93,  351,  325,  938, 1326,  698,
+ /*   230 */   706, 1326,  242,  412,   99,  100,   90,  842,  842,  854,
+ /*   240 */   857,  846,  846,   97,   97,   98,   98,   98,   98,  347,
+ /*   250 */    96,   96,   96,   96,   95,   95,   94,   94,   94,   93,
+ /*   260 */   351,  325,  938, 1327,  384,  699, 1327,  381,  379,   99,
+ /*   270 */   100,   90,  842,  842,  854,  857,  846,  846,   97,   97,
+ /*   280 */    98,   98,   98,   98,  701,   96,   96,   96,   96,   95,
+ /*   290 */    95,   94,   94,   94,   93,  351,  325,   92,   89,  178,
+ /*   300 */   833,  936,  373,  700,   99,  100,   90,  842,  842,  854,
+ /*   310 */   857,  846,  846,   97,   97,   98,   98,   98,   98,  375,
+ /*   320 */    96,   96,   96,   96,   95,   95,   94,   94,   94,   93,
+ /*   330 */   351,  325, 1276,  947,  354,  818,  936,  739,  739,   99,
+ /*   340 */   100,   90,  842,  842,  854,  857,  846,  846,   97,   97,
+ /*   350 */    98,   98,   98,   98,  230,   96,   96,   96,   96,   95,
+ /*   360 */    95,   94,   94,   94,   93,  351,  325,  969,  227,   92,
+ /*   370 */    89,  178,  373,  300,   99,  100,   90,  842,  842,  854,
+ /*   380 */   857,  846,  846,   97,   97,   98,   98,   98,   98,  921,
+ /*   390 */    96,   96,   96,   96,   95,   95,   94,   94,   94,   93,
+ /*   400 */   351,  325,  449,  447,  447,  447,  147,  737,  737,   99,
+ /*   410 */   100,   90,  842,  842,  854,  857,  846,  846,   97,   97,
+ /*   420 */    98,   98,   98,   98,  296,   96,   96,   96,   96,   95,
+ /*   430 */    95,   94,   94,   94,   93,  351,  325,  419,  231,  958,
+ /*   440 */   958,  158,   25,  422,   99,  100,   90,  842,  842,  854,
+ /*   450 */   857,  846,  846,   97,   97,   98,   98,   98,   98,  450,
+ /*   460 */    96,   96,   96,   96,   95,   95,   94,   94,   94,   93,
+ /*   470 */   351,  443,  224,  224,  420,  958,  958,  962,  325,   52,
+ /*   480 */    52,  959,  960,  176,  415,   78,   99,  100,   90,  842,
+ /*   490 */   842,  854,  857,  846,  846,   97,   97,   98,   98,   98,
+ /*   500 */    98,  379,   96,   96,   96,   96,   95,   95,   94,   94,
+ /*   510 */    94,   93,  351,  325,  428,  418,  298,  959,  960,  962,
+ /*   520 */    81,   99,   88,   90,  842,  842,  854,  857,  846,  846,
+ /*   530 */    97,   97,   98,   98,   98,   98,  717,   96,   96,   96,
+ /*   540 */    96,   95,   95,   94,   94,   94,   93,  351,  325,  843,
+ /*   550 */   843,  855,  858,  996,  318,  343,  379,  100,   90,  842,
+ /*   560 */   842,  854,  857,  846,  846,   97,   97,   98,   98,   98,
+ /*   570 */    98,  450,   96,   96,   96,   96,   95,   95,   94,   94,
+ /*   580 */    94,   93,  351,  325,  350,  350,  350,  260,  377,  340,
+ /*   590 */   929,   52,   52,   90,  842,  842,  854,  857,  846,  846,
+ /*   600 */    97,   97,   98,   98,   98,   98,  361,   96,   96,   96,
+ /*   610 */    96,   95,   95,   94,   94,   94,   93,  351,   86,  445,
+ /*   620 */   847,    3, 1203,  361,  360,  378,  344,  813,  958,  958,
+ /*   630 */  1300,   86,  445,  729,    3,  212,  169,  287,  405,  282,
+ /*   640 */   404,  199,  232,  450,  300,  760,   83,   84,  280,  245,
+ /*   650 */   262,  365,  251,   85,  352,  352,   92,   89,  178,   83,
+ /*   660 */    84,  242,  412,   52,   52,  448,   85,  352,  352,  246,
+ /*   670 */   959,  960,  194,  455,  670,  402,  399,  398,  448,  243,
+ /*   680 */   221,  114,  434,  776,  361,  450,  397,  268,  747,  224,
+ /*   690 */   224,  132,  132,  198,  832,  434,  452,  451,  428,  427,
+ /*   700 */   819,  415,  734,  713,  132,   52,   52,  832,  268,  452,
+ /*   710 */   451,  734,  194,  819,  363,  402,  399,  398,  450, 1271,
+ /*   720 */  1271,   23,  958,  958,   86,  445,  397,    3,  228,  429,
+ /*   730 */   895,  824,  824,  826,  827,   19,  203,  720,   52,   52,
+ /*   740 */   428,  408,  439,  249,  824,  824,  826,  827,   19,  229,
+ /*   750 */   403,  153,   83,   84,  761,  177,  241,  450,  721,   85,
+ /*   760 */   352,  352,  120,  157,  959,  960,   58,  977,  409,  355,
+ /*   770 */   330,  448,  268,  428,  430,  320,  790,   32,   32,   86,
+ /*   780 */   445,  776,    3,  341,   98,   98,   98,   98,  434,   96,
+ /*   790 */    96,   96,   96,   95,   95,   94,   94,   94,   93,  351,
+ /*   800 */   832,  120,  452,  451,  813,  887,  819,   83,   84,  977,
+ /*   810 */   813,  132,  410,  920,   85,  352,  352,  132,  407,  789,
+ /*   820 */   958,  958,   92,   89,  178,  917,  448,  262,  370,  261,
+ /*   830 */    82,  914,   80,  262,  370,  261,  776,  824,  824,  826,
+ /*   840 */   827,   19,  934,  434,   96,   96,   96,   96,   95,   95,
+ /*   850 */    94,   94,   94,   93,  351,  832,   74,  452,  451,  958,
+ /*   860 */   958,  819,  959,  960,  120,   92,   89,  178,  945,    2,
+ /*   870 */   918,  965,  268,    1,  976,   76,  445,  762,    3,  708,
+ /*   880 */   901,  901,  387,  958,  958,  757,  919,  371,  740,  778,
+ /*   890 */   756,  257,  824,  824,  826,  827,   19,  417,  741,  450,
+ /*   900 */    24,  959,  960,   83,   84,  369,  958,  958,  177,  226,
+ /*   910 */    85,  352,  352,  885,  315,  314,  313,  215,  311,   10,
+ /*   920 */    10,  683,  448,  349,  348,  959,  960,  909,  777,  157,
+ /*   930 */   120,  958,  958,  337,  776,  416,  711,  310,  450,  434,
+ /*   940 */   450,  321,  450,  791,  103,  200,  175,  450,  959,  960,
+ /*   950 */   908,  832,  792,  452,  451,    9,    9,  819,   10,   10,
+ /*   960 */    52,   52,   51,   51,  180,  716,  248,   10,   10,  171,
+ /*   970 */   170,  167,  339,  959,  960,  247,  984,  702,  702,  450,
+ /*   980 */   715,  233,  686,  982,  889,  983,  182,  914,  824,  824,
+ /*   990 */   826,  827,   19,  183,  256,  423,  132,  181,  394,   10,
+ /*  1000 */    10,  889,  891,  749,  958,  958,  917,  268,  985,  198,
+ /*  1010 */   985,  349,  348,  425,  415,  299,  817,  832,  326,  825,
+ /*  1020 */   120,  332,  133,  819,  268,   98,   98,   98,   98,   91,
+ /*  1030 */    96,   96,   96,   96,   95,   95,   94,   94,   94,   93,
+ /*  1040 */   351,  157,  810,  371,  382,  359,  959,  960,  358,  268,
+ /*  1050 */   450,  918,  368,  324,  824,  824,  826,  450,  709,  450,
+ /*  1060 */   264,  380,  889,  450,  877,  746,  253,  919,  255,  433,
+ /*  1070 */    36,   36,  234,  450,  234,  120,  269,   37,   37,   12,
+ /*  1080 */    12,  334,  272,   27,   27,  450,  330,  118,  450,  162,
+ /*  1090 */   742,  280,  450,   38,   38,  450,  985,  356,  985,  450,
+ /*  1100 */   709, 1210,  450,  132,  450,   39,   39,  450,   40,   40,
+ /*  1110 */   450,  362,   41,   41,  450,   42,   42,  450,  254,   28,
+ /*  1120 */    28,  450,   29,   29,   31,   31,  450,   43,   43,  450,
+ /*  1130 */    44,   44,  450,  714,   45,   45,  450,   11,   11,  767,
+ /*  1140 */   450,   46,   46,  450,  268,  450,  105,  105,  450,   47,
+ /*  1150 */    47,  450,   48,   48,  450,  237,   33,   33,  450,  172,
+ /*  1160 */    49,   49,  450,   50,   50,   34,   34,  274,  122,  122,
+ /*  1170 */   450,  123,  123,  450,  124,  124,  450,  898,   56,   56,
+ /*  1180 */   450,  897,   35,   35,  450,  267,  450,  817,  450,  817,
+ /*  1190 */   106,  106,  450,   53,   53,  385,  107,  107,  450,  817,
+ /*  1200 */   108,  108,  817,  450,  104,  104,  121,  121,  119,  119,
+ /*  1210 */   450,  117,  112,  112,  450,  276,  450,  225,  111,  111,
+ /*  1220 */   450,  730,  450,  109,  109,  450,  673,  674,  675,  912,
+ /*  1230 */   110,  110,  317,  998,   55,   55,   57,   57,  692,  331,
+ /*  1240 */    54,   54,   26,   26,  696,   30,   30,  317,  937,  197,
+ /*  1250 */   196,  195,  335,  281,  336,  446,  331,  745,  689,  436,
+ /*  1260 */   440,  444,  120,   72,  386,  223,  175,  345,  757,  933,
+ /*  1270 */    20,  286,  319,  756,  815,  372,  374,  202,  202,  202,
+ /*  1280 */   263,  395,  285,   74,  208,   21,  696,  719,  718,  884,
+ /*  1290 */   120,  120,  120,  120,  120,  754,  278,  828,   77,   74,
+ /*  1300 */   726,  727,  785,  783,  880,  202,  999,  208,  894,  893,
+ /*  1310 */   894,  893,  694,  816,  763,  116,  774, 1290,  431,  432,
+ /*  1320 */   302,  999,  390,  303,  823,  697,  691,  680,  159,  289,
+ /*  1330 */   679,  884,  681,  952,  291,  218,  293,    7,  316,  828,
+ /*  1340 */   173,  805,  259,  364,  252,  911,  376,  713,  295,  435,
+ /*  1350 */   308,  168,  955,  993,  135,  400,  990,  284,  882,  881,
+ /*  1360 */   205,  928,  926,   59,  333,   62,  144,  156,  130,   72,
+ /*  1370 */   802,  366,  367,  393,  137,  185,  189,  160,  139,  383,
+ /*  1380 */    67,  896,  140,  141,  142,  148,  389,  812,  775,  266,
+ /*  1390 */   219,  190,  154,  391,  913,  876,  271,  406,  191,  322,
+ /*  1400 */   682,  733,  192,  342,  732,  724,  731,  711,  723,  421,
+ /*  1410 */   705,   71,  323,    6,  204,  771,  288,   79,  297,  346,
+ /*  1420 */   772,  704,  290,  283,  703,  770,  292,  294,  967,  239,
+ /*  1430 */   769,  102,  862,  438,  426,  240,  424,  442,   73,  213,
+ /*  1440 */   688,  238,   22,  453,  953,  214,  217,  216,  454,  677,
+ /*  1450 */   676,  671,  753,  125,  115,  235,  126,  669,  353,  166,
+ /*  1460 */   127,  244,  179,  357,  306,  304,  305,  307,  113,  892,
+ /*  1470 */   327,  890,  811,  328,  134,  128,  136,  138,  743,  258,
+ /*  1480 */   907,  184,  143,  129,  910,  186,   63,   64,  145,  187,
+ /*  1490 */   906,   65,    8,   66,   13,  188,  202,  899,  265,  149,
+ /*  1500 */   987,  388,  150,  685,  161,  392,  285,  193,  279,  396,
+ /*  1510 */   151,  401,   68,   14,   15,  722,   69,  236,  831,  131,
+ /*  1520 */   830,  860,   70,  751,   16,  414,  755,    4,  174,  220,
+ /*  1530 */   222,  784,  201,  152,  779,   77,   74,   17,   18,  875,
+ /*  1540 */   861,  859,  916,  864,  915,  207,  206,  942,  163,  437,
+ /*  1550 */   948,  943,  164,  209, 1002,  441,  863,  165,  210,  829,
+ /*  1560 */   695,   87,  312,  211, 1292, 1291,  309,
+};
+static const YYCODETYPE yy_lookahead[] = {
+ /*     0 */    19,   95,   53,   97,   22,   24,   24,  101,   27,   28,
+ /*    10 */    29,   30,   31,   32,   33,   34,   35,   36,   37,   38,
+ /*    20 */    39,   40,   41,  152,   43,   44,   45,   46,   47,   48,
+ /*    30 */    49,   50,   51,   52,   53,   19,   55,   55,  132,  133,
+ /*    40 */   134,    1,    2,   27,   28,   29,   30,   31,   32,   33,
+ /*    50 */    34,   35,   36,   37,   38,   39,   40,   41,  187,   43,
+ /*    60 */    44,   45,   46,   47,   48,   49,   50,   51,   52,   53,
+ /*    70 */    47,   48,   49,   50,   51,   52,   53,   61,   97,   97,
+ /*    80 */    19,   49,   50,   51,   52,   53,   70,   26,   27,   28,
+ /*    90 */    29,   30,   31,   32,   33,   34,   35,   36,   37,   38,
+ /*   100 */    39,   40,   41,  152,   43,   44,   45,   46,   47,   48,
+ /*   110 */    49,   50,   51,   52,   53,  144,  145,  146,  147,   19,
+ /*   120 */    16,   22,   92,  172,  173,   52,   53,   27,   28,   29,
+ /*   130 */    30,   31,   32,   33,   34,   35,   36,   37,   38,   39,
+ /*   140 */    40,   41,   81,   43,   44,   45,   46,   47,   48,   49,
+ /*   150 */    50,   51,   52,   53,   55,   56,   19,  152,  207,  208,
+ /*   160 */   115,   24,  117,  118,   27,   28,   29,   30,   31,   32,
+ /*   170 */    33,   34,   35,   36,   37,   38,   39,   40,   41,   79,
+ /*   180 */    43,   44,   45,   46,   47,   48,   49,   50,   51,   52,
+ /*   190 */    53,   19,   88,  157,   90,   23,   97,   98,  193,   27,
+ /*   200 */    28,   29,   30,   31,   32,   33,   34,   35,   36,   37,
+ /*   210 */    38,   39,   40,   41,  152,   43,   44,   45,   46,   47,
+ /*   220 */    48,   49,   50,   51,   52,   53,   19,   22,   23,  172,
+ /*   230 */    23,   26,  119,  120,   27,   28,   29,   30,   31,   32,
+ /*   240 */    33,   34,   35,   36,   37,   38,   39,   40,   41,  187,
+ /*   250 */    43,   44,   45,   46,   47,   48,   49,   50,   51,   52,
+ /*   260 */    53,   19,   22,   23,  228,   23,   26,  231,  152,   27,
+ /*   270 */    28,   29,   30,   31,   32,   33,   34,   35,   36,   37,
+ /*   280 */    38,   39,   40,   41,  172,   43,   44,   45,   46,   47,
+ /*   290 */    48,   49,   50,   51,   52,   53,   19,  221,  222,  223,
+ /*   300 */    23,   96,  152,  172,   27,   28,   29,   30,   31,   32,
+ /*   310 */    33,   34,   35,   36,   37,   38,   39,   40,   41,  152,
+ /*   320 */    43,   44,   45,   46,   47,   48,   49,   50,   51,   52,
+ /*   330 */    53,   19,    0,    1,    2,   23,   96,  190,  191,   27,
+ /*   340 */    28,   29,   30,   31,   32,   33,   34,   35,   36,   37,
+ /*   350 */    38,   39,   40,   41,  238,   43,   44,   45,   46,   47,
+ /*   360 */    48,   49,   50,   51,   52,   53,   19,  185,  218,  221,
+ /*   370 */   222,  223,  152,  152,   27,   28,   29,   30,   31,   32,
+ /*   380 */    33,   34,   35,   36,   37,   38,   39,   40,   41,  241,
+ /*   390 */    43,   44,   45,   46,   47,   48,   49,   50,   51,   52,
+ /*   400 */    53,   19,  152,  168,  169,  170,   22,  190,  191,   27,
+ /*   410 */    28,   29,   30,   31,   32,   33,   34,   35,   36,   37,
+ /*   420 */    38,   39,   40,   41,  152,   43,   44,   45,   46,   47,
+ /*   430 */    48,   49,   50,   51,   52,   53,   19,   19,  218,   55,
+ /*   440 */    56,   24,   22,  152,   27,   28,   29,   30,   31,   32,
+ /*   450 */    33,   34,   35,   36,   37,   38,   39,   40,   41,  152,
+ /*   460 */    43,   44,   45,   46,   47,   48,   49,   50,   51,   52,
+ /*   470 */    53,  250,  194,  195,   56,   55,   56,   55,   19,  172,
+ /*   480 */   173,   97,   98,  152,  206,  138,   27,   28,   29,   30,
+ /*   490 */    31,   32,   33,   34,   35,   36,   37,   38,   39,   40,
+ /*   500 */    41,  152,   43,   44,   45,   46,   47,   48,   49,   50,
+ /*   510 */    51,   52,   53,   19,  207,  208,  152,   97,   98,   97,
+ /*   520 */   138,   27,   28,   29,   30,   31,   32,   33,   34,   35,
+ /*   530 */    36,   37,   38,   39,   40,   41,  181,   43,   44,   45,
+ /*   540 */    46,   47,   48,   49,   50,   51,   52,   53,   19,   30,
+ /*   550 */    31,   32,   33,  247,  248,   19,  152,   28,   29,   30,
+ /*   560 */    31,   32,   33,   34,   35,   36,   37,   38,   39,   40,
+ /*   570 */    41,  152,   43,   44,   45,   46,   47,   48,   49,   50,
+ /*   580 */    51,   52,   53,   19,  168,  169,  170,  238,   19,   53,
+ /*   590 */   152,  172,  173,   29,   30,   31,   32,   33,   34,   35,
+ /*   600 */    36,   37,   38,   39,   40,   41,  152,   43,   44,   45,
+ /*   610 */    46,   47,   48,   49,   50,   51,   52,   53,   19,   20,
+ /*   620 */   101,   22,   23,  169,  170,   56,  207,   85,   55,   56,
+ /*   630 */    23,   19,   20,   26,   22,   99,  100,  101,  102,  103,
+ /*   640 */   104,  105,  238,  152,  152,  210,   47,   48,  112,  152,
+ /*   650 */   108,  109,  110,   54,   55,   56,  221,  222,  223,   47,
+ /*   660 */    48,  119,  120,  172,  173,   66,   54,   55,   56,  152,
+ /*   670 */    97,   98,   99,  148,  149,  102,  103,  104,   66,  154,
+ /*   680 */    23,  156,   83,   26,  230,  152,  113,  152,  163,  194,
+ /*   690 */   195,   92,   92,   30,   95,   83,   97,   98,  207,  208,
+ /*   700 */   101,  206,  179,  180,   92,  172,  173,   95,  152,   97,
+ /*   710 */    98,  188,   99,  101,  219,  102,  103,  104,  152,  119,
+ /*   720 */   120,  196,   55,   56,   19,   20,  113,   22,  193,  163,
+ /*   730 */    11,  132,  133,  134,  135,  136,   24,   65,  172,  173,
+ /*   740 */   207,  208,  250,  152,  132,  133,  134,  135,  136,  193,
+ /*   750 */    78,   84,   47,   48,   49,   98,  199,  152,   86,   54,
+ /*   760 */    55,   56,  196,  152,   97,   98,  209,   55,  163,  244,
+ /*   770 */   107,   66,  152,  207,  208,  164,  175,  172,  173,   19,
+ /*   780 */    20,  124,   22,  111,   38,   39,   40,   41,   83,   43,
+ /*   790 */    44,   45,   46,   47,   48,   49,   50,   51,   52,   53,
+ /*   800 */    95,  196,   97,   98,   85,  152,  101,   47,   48,   97,
+ /*   810 */    85,   92,  207,  193,   54,   55,   56,   92,   49,  175,
+ /*   820 */    55,   56,  221,  222,  223,   12,   66,  108,  109,  110,
+ /*   830 */   137,  163,  139,  108,  109,  110,   26,  132,  133,  134,
+ /*   840 */   135,  136,  152,   83,   43,   44,   45,   46,   47,   48,
+ /*   850 */    49,   50,   51,   52,   53,   95,   26,   97,   98,   55,
+ /*   860 */    56,  101,   97,   98,  196,  221,  222,  223,  146,  147,
+ /*   870 */    57,  171,  152,   22,   26,   19,   20,   49,   22,  179,
+ /*   880 */   108,  109,  110,   55,   56,  116,   73,  219,   75,  124,
+ /*   890 */   121,  152,  132,  133,  134,  135,  136,  163,   85,  152,
+ /*   900 */   232,   97,   98,   47,   48,  237,   55,   56,   98,    5,
+ /*   910 */    54,   55,   56,  193,   10,   11,   12,   13,   14,  172,
+ /*   920 */   173,   17,   66,   47,   48,   97,   98,  152,  124,  152,
+ /*   930 */   196,   55,   56,  186,  124,  152,  106,  160,  152,   83,
+ /*   940 */   152,  164,  152,   61,   22,  211,  212,  152,   97,   98,
+ /*   950 */   152,   95,   70,   97,   98,  172,  173,  101,  172,  173,
+ /*   960 */   172,  173,  172,  173,   60,  181,   62,  172,  173,   47,
+ /*   970 */    48,  123,  186,   97,   98,   71,  100,   55,   56,  152,
+ /*   980 */   181,  186,   21,  107,  152,  109,   82,  163,  132,  133,
+ /*   990 */   134,  135,  136,   89,   16,  207,   92,   93,   19,  172,
+ /*  1000 */   173,  169,  170,  195,   55,   56,   12,  152,  132,   30,
+ /*  1010 */   134,   47,   48,  186,  206,  225,  152,   95,  114,   97,
+ /*  1020 */   196,  245,  246,  101,  152,   38,   39,   40,   41,   42,
+ /*  1030 */    43,   44,   45,   46,   47,   48,   49,   50,   51,   52,
+ /*  1040 */    53,  152,  163,  219,  152,  141,   97,   98,  193,  152,
+ /*  1050 */   152,   57,   91,  164,  132,  133,  134,  152,   55,  152,
+ /*  1060 */   152,  237,  230,  152,  103,  193,   88,   73,   90,   75,
+ /*  1070 */   172,  173,  183,  152,  185,  196,  152,  172,  173,  172,
+ /*  1080 */   173,  217,  152,  172,  173,  152,  107,   22,  152,   24,
+ /*  1090 */   193,  112,  152,  172,  173,  152,  132,  242,  134,  152,
+ /*  1100 */    97,  140,  152,   92,  152,  172,  173,  152,  172,  173,
+ /*  1110 */   152,  100,  172,  173,  152,  172,  173,  152,  140,  172,
+ /*  1120 */   173,  152,  172,  173,  172,  173,  152,  172,  173,  152,
+ /*  1130 */   172,  173,  152,  152,  172,  173,  152,  172,  173,  213,
+ /*  1140 */   152,  172,  173,  152,  152,  152,  172,  173,  152,  172,
+ /*  1150 */   173,  152,  172,  173,  152,  210,  172,  173,  152,   26,
+ /*  1160 */   172,  173,  152,  172,  173,  172,  173,  152,  172,  173,
+ /*  1170 */   152,  172,  173,  152,  172,  173,  152,   59,  172,  173,
+ /*  1180 */   152,   63,  172,  173,  152,  193,  152,  152,  152,  152,
+ /*  1190 */   172,  173,  152,  172,  173,   77,  172,  173,  152,  152,
+ /*  1200 */   172,  173,  152,  152,  172,  173,  172,  173,  172,  173,
+ /*  1210 */   152,   22,  172,  173,  152,  152,  152,   22,  172,  173,
+ /*  1220 */   152,  152,  152,  172,  173,  152,    7,    8,    9,  163,
+ /*  1230 */   172,  173,   22,   23,  172,  173,  172,  173,  166,  167,
+ /*  1240 */   172,  173,  172,  173,   55,  172,  173,   22,   23,  108,
+ /*  1250 */   109,  110,  217,  152,  217,  166,  167,  163,  163,  163,
+ /*  1260 */   163,  163,  196,  130,  217,  211,  212,  217,  116,   23,
+ /*  1270 */    22,  101,   26,  121,   23,   23,   23,   26,   26,   26,
+ /*  1280 */    23,   23,  112,   26,   26,   37,   97,  100,  101,   55,
+ /*  1290 */   196,  196,  196,  196,  196,   23,   23,   55,   26,   26,
+ /*  1300 */     7,    8,   23,  152,   23,   26,   96,   26,  132,  132,
+ /*  1310 */   134,  134,   23,  152,  152,   26,  152,  122,  152,  191,
+ /*  1320 */   152,   96,  234,  152,  152,  152,  152,  152,  197,  210,
+ /*  1330 */   152,   97,  152,  152,  210,  233,  210,  198,  150,   97,
+ /*  1340 */   184,  201,  239,  214,  214,  201,  239,  180,  214,  227,
+ /*  1350 */   200,  198,  155,   67,  243,  176,   69,  175,  175,  175,
+ /*  1360 */   122,  159,  159,  240,  159,  240,   22,  220,   27,  130,
+ /*  1370 */   201,   18,  159,   18,  189,  158,  158,  220,  192,  159,
+ /*  1380 */   137,  236,  192,  192,  192,  189,   74,  189,  159,  235,
+ /*  1390 */   159,  158,   22,  177,  201,  201,  159,  107,  158,  177,
+ /*  1400 */   159,  174,  158,   76,  174,  182,  174,  106,  182,  125,
+ /*  1410 */   174,  107,  177,   22,  159,  216,  215,  137,  159,   53,
+ /*  1420 */   216,  176,  215,  174,  174,  216,  215,  215,  174,  229,
+ /*  1430 */   216,  129,  224,  177,  126,  229,  127,  177,  128,   25,
+ /*  1440 */   162,  226,   26,  161,   13,  153,    6,  153,  151,  151,
+ /*  1450 */   151,  151,  205,  165,  178,  178,  165,    4,    3,   22,
+ /*  1460 */   165,  142,   15,   94,  202,  204,  203,  201,   16,   23,
+ /*  1470 */   249,   23,  120,  249,  246,  111,  131,  123,   20,   16,
+ /*  1480 */     1,  125,  123,  111,   56,   64,   37,   37,  131,  122,
+ /*  1490 */     1,   37,    5,   37,   22,  107,   26,   80,  140,   80,
+ /*  1500 */    87,   72,  107,   20,   24,   19,  112,  105,   23,   79,
+ /*  1510 */    22,   79,   22,   22,   22,   58,   22,   79,   23,   68,
+ /*  1520 */    23,   23,   26,  116,   22,   26,   23,   22,  122,   23,
+ /*  1530 */    23,   56,   64,   22,  124,   26,   26,   64,   64,   23,
+ /*  1540 */    23,   23,   23,   11,   23,   22,   26,   23,   22,   24,
+ /*  1550 */     1,   23,   22,   26,  251,   24,   23,   22,  122,   23,
+ /*  1560 */    23,   22,   15,  122,  122,  122,   23,
+};
+#define YY_SHIFT_USE_DFLT (1567)
+#define YY_SHIFT_COUNT    (455)
+#define YY_SHIFT_MIN      (-94)
+#define YY_SHIFT_MAX      (1549)
+static const short yy_shift_ofst[] = {
+ /*     0 */    40,  599,  904,  612,  760,  760,  760,  760,  725,  -19,
+ /*    10 */    16,   16,  100,  760,  760,  760,  760,  760,  760,  760,
+ /*    20 */   876,  876,  573,  542,  719,  600,   61,  137,  172,  207,
+ /*    30 */   242,  277,  312,  347,  382,  417,  459,  459,  459,  459,
+ /*    40 */   459,  459,  459,  459,  459,  459,  459,  459,  459,  459,
+ /*    50 */   459,  459,  459,  494,  459,  529,  564,  564,  705,  760,
+ /*    60 */   760,  760,  760,  760,  760,  760,  760,  760,  760,  760,
+ /*    70 */   760,  760,  760,  760,  760,  760,  760,  760,  760,  760,
+ /*    80 */   760,  760,  760,  760,  760,  760,  760,  760,  760,  760,
+ /*    90 */   856,  760,  760,  760,  760,  760,  760,  760,  760,  760,
+ /*   100 */   760,  760,  760,  760,  987,  746,  746,  746,  746,  746,
+ /*   110 */   801,   23,   32,  949,  961,  979,  964,  964,  949,   73,
+ /*   120 */   113,  -51, 1567, 1567, 1567,  536,  536,  536,   99,   99,
+ /*   130 */   813,  813,  667,  205,  240,  949,  949,  949,  949,  949,
+ /*   140 */   949,  949,  949,  949,  949,  949,  949,  949,  949,  949,
+ /*   150 */   949,  949,  949,  949,  949,  332, 1011,  422,  422,  113,
+ /*   160 */    30,   30,   30,   30,   30,   30, 1567, 1567, 1567,  922,
+ /*   170 */   -94,  -94,  384,  613,  828,  420,  765,  804,  851,  949,
+ /*   180 */   949,  949,  949,  949,  949,  949,  949,  949,  949,  949,
+ /*   190 */   949,  949,  949,  949,  949,  672,  672,  672,  949,  949,
+ /*   200 */   657,  949,  949,  949,  -18,  949,  949,  994,  949,  949,
+ /*   210 */   949,  949,  949,  949,  949,  949,  949,  949,  772, 1118,
+ /*   220 */   712,  712,  712,  810,   45,  769, 1219, 1133,  418,  418,
+ /*   230 */   569, 1133,  569,  830,  607,  663,  882,  418,  693,  882,
+ /*   240 */   882,  848, 1152, 1065, 1286, 1238, 1238, 1287, 1287, 1238,
+ /*   250 */  1344, 1341, 1239, 1353, 1353, 1353, 1353, 1238, 1355, 1239,
+ /*   260 */  1344, 1341, 1341, 1239, 1238, 1355, 1243, 1312, 1238, 1238,
+ /*   270 */  1355, 1370, 1238, 1355, 1238, 1355, 1370, 1290, 1290, 1290,
+ /*   280 */  1327, 1370, 1290, 1301, 1290, 1327, 1290, 1290, 1284, 1304,
+ /*   290 */  1284, 1304, 1284, 1304, 1284, 1304, 1238, 1391, 1238, 1280,
+ /*   300 */  1370, 1366, 1366, 1370, 1302, 1308, 1310, 1309, 1239, 1414,
+ /*   310 */  1416, 1431, 1431, 1440, 1440, 1440, 1440, 1567, 1567, 1567,
+ /*   320 */  1567, 1567, 1567, 1567, 1567,  519,  978, 1210, 1225,  104,
+ /*   330 */  1141, 1189, 1246, 1248, 1251, 1252, 1253, 1257, 1258, 1273,
+ /*   340 */  1003, 1187, 1293, 1170, 1272, 1279, 1234, 1281, 1176, 1177,
+ /*   350 */  1289, 1242, 1195, 1453, 1455, 1437, 1319, 1447, 1369, 1452,
+ /*   360 */  1446, 1448, 1352, 1345, 1364, 1354, 1458, 1356, 1463, 1479,
+ /*   370 */  1359, 1357, 1449, 1450, 1454, 1456, 1372, 1428, 1421, 1367,
+ /*   380 */  1489, 1487, 1472, 1388, 1358, 1417, 1470, 1419, 1413, 1429,
+ /*   390 */  1395, 1480, 1483, 1486, 1394, 1402, 1488, 1430, 1490, 1491,
+ /*   400 */  1485, 1492, 1432, 1457, 1494, 1438, 1451, 1495, 1497, 1498,
+ /*   410 */  1496, 1407, 1502, 1503, 1505, 1499, 1406, 1506, 1507, 1475,
+ /*   420 */  1468, 1511, 1410, 1509, 1473, 1510, 1474, 1516, 1509, 1517,
+ /*   430 */  1518, 1519, 1520, 1521, 1523, 1532, 1524, 1526, 1525, 1527,
+ /*   440 */  1528, 1530, 1531, 1527, 1533, 1535, 1536, 1537, 1539, 1436,
+ /*   450 */  1441, 1442, 1443, 1543, 1547, 1549,
+};
+#define YY_REDUCE_USE_DFLT (-130)
+#define YY_REDUCE_COUNT (324)
+#define YY_REDUCE_MIN   (-129)
+#define YY_REDUCE_MAX   (1300)
+static const short yy_reduce_ofst[] = {
+ /*     0 */   -29,  566,  525,  605,  -49,  307,  491,  533,  668,  435,
+ /*    10 */   601,  644,  148,  747,  786,  795,  419,  788,  827,  790,
+ /*    20 */   454,  832,  889,  495,  824,  734,   76,   76,   76,   76,
+ /*    30 */    76,   76,   76,   76,   76,   76,   76,   76,   76,   76,
+ /*    40 */    76,   76,   76,   76,   76,   76,   76,   76,   76,   76,
+ /*    50 */    76,   76,   76,   76,   76,   76,   76,   76,  783,  898,
+ /*    60 */   905,  907,  911,  921,  933,  936,  940,  943,  947,  950,
+ /*    70 */   952,  955,  958,  962,  965,  969,  974,  977,  980,  984,
+ /*    80 */   988,  991,  993,  996,  999, 1002, 1006, 1010, 1018, 1021,
+ /*    90 */  1024, 1028, 1032, 1034, 1036, 1040, 1046, 1051, 1058, 1062,
+ /*   100 */  1064, 1068, 1070, 1073,   76,   76,   76,   76,   76,   76,
+ /*   110 */    76,   76,   76,  855,   36,  523,  235,  416,  777,   76,
+ /*   120 */   278,   76,   76,   76,   76,  700,  700,  700,  150,  220,
+ /*   130 */   147,  217,  221,  306,  306,  611,    5,  535,  556,  620,
+ /*   140 */   720,  872,  897,  116,  864,  349, 1035, 1037,  404, 1047,
+ /*   150 */   992, -129, 1050,  492,   62,  722,  879, 1072, 1089,  808,
+ /*   160 */  1066, 1094, 1095, 1096, 1097, 1098,  776, 1054,  557,   57,
+ /*   170 */   112,  131,  167,  182,  250,  272,  291,  331,  364,  438,
+ /*   180 */   497,  517,  591,  653,  690,  739,  775,  798,  892,  908,
+ /*   190 */   924,  930, 1015, 1063, 1069,  355,  784,  799,  981, 1101,
+ /*   200 */   926, 1151, 1161, 1162,  945, 1164, 1166, 1128, 1168, 1171,
+ /*   210 */  1172,  250, 1173, 1174, 1175, 1178, 1180, 1181, 1088, 1102,
+ /*   220 */  1119, 1124, 1126,  926, 1131, 1139, 1188, 1140, 1129, 1130,
+ /*   230 */  1103, 1144, 1107, 1179, 1156, 1167, 1182, 1134, 1122, 1183,
+ /*   240 */  1184, 1150, 1153, 1197, 1111, 1202, 1203, 1123, 1125, 1205,
+ /*   250 */  1147, 1185, 1169, 1186, 1190, 1191, 1192, 1213, 1217, 1193,
+ /*   260 */  1157, 1196, 1198, 1194, 1220, 1218, 1145, 1154, 1229, 1231,
+ /*   270 */  1233, 1216, 1237, 1240, 1241, 1244, 1222, 1227, 1230, 1232,
+ /*   280 */  1223, 1235, 1236, 1245, 1249, 1226, 1250, 1254, 1199, 1201,
+ /*   290 */  1204, 1207, 1209, 1211, 1214, 1212, 1255, 1208, 1259, 1215,
+ /*   300 */  1256, 1200, 1206, 1260, 1247, 1261, 1263, 1262, 1266, 1278,
+ /*   310 */  1282, 1292, 1294, 1297, 1298, 1299, 1300, 1221, 1224, 1228,
+ /*   320 */  1288, 1291, 1276, 1277, 1295,
+};
+static const YYACTIONTYPE yy_default[] = {
+ /*     0 */  1281, 1271, 1271, 1271, 1203, 1203, 1203, 1203, 1271, 1096,
+ /*    10 */  1125, 1125, 1255, 1332, 1332, 1332, 1332, 1332, 1332, 1202,
+ /*    20 */  1332, 1332, 1332, 1332, 1271, 1100, 1131, 1332, 1332, 1332,
+ /*    30 */  1332, 1204, 1205, 1332, 1332, 1332, 1254, 1256, 1141, 1140,
+ /*    40 */  1139, 1138, 1237, 1112, 1136, 1129, 1133, 1204, 1198, 1199,
+ /*    50 */  1197, 1201, 1205, 1332, 1132, 1167, 1182, 1166, 1332, 1332,
+ /*    60 */  1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332,
+ /*    70 */  1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332,
+ /*    80 */  1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332,
+ /*    90 */  1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332,
+ /*   100 */  1332, 1332, 1332, 1332, 1176, 1181, 1188, 1180, 1177, 1169,
+ /*   110 */  1168, 1170, 1171, 1332, 1019, 1067, 1332, 1332, 1332, 1172,
+ /*   120 */  1332, 1173, 1185, 1184, 1183, 1262, 1289, 1288, 1332, 1332,
+ /*   130 */  1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332,
+ /*   140 */  1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332,
+ /*   150 */  1332, 1332, 1332, 1332, 1332, 1281, 1271, 1025, 1025, 1332,
+ /*   160 */  1271, 1271, 1271, 1271, 1271, 1271, 1267, 1100, 1091, 1332,
+ /*   170 */  1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332,
+ /*   180 */  1259, 1257, 1332, 1218, 1332, 1332, 1332, 1332, 1332, 1332,
+ /*   190 */  1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332,
+ /*   200 */  1332, 1332, 1332, 1332, 1096, 1332, 1332, 1332, 1332, 1332,
+ /*   210 */  1332, 1332, 1332, 1332, 1332, 1332, 1332, 1283, 1332, 1232,
+ /*   220 */  1096, 1096, 1096, 1098, 1080, 1090, 1004, 1135, 1114, 1114,
+ /*   230 */  1321, 1135, 1321, 1042, 1303, 1039, 1125, 1114, 1200, 1125,
+ /*   240 */  1125, 1097, 1090, 1332, 1324, 1105, 1105, 1323, 1323, 1105,
+ /*   250 */  1146, 1070, 1135, 1076, 1076, 1076, 1076, 1105, 1016, 1135,
+ /*   260 */  1146, 1070, 1070, 1135, 1105, 1016, 1236, 1318, 1105, 1105,
+ /*   270 */  1016, 1211, 1105, 1016, 1105, 1016, 1211, 1068, 1068, 1068,
+ /*   280 */  1057, 1211, 1068, 1042, 1068, 1057, 1068, 1068, 1118, 1113,
+ /*   290 */  1118, 1113, 1118, 1113, 1118, 1113, 1105, 1206, 1105, 1332,
+ /*   300 */  1211, 1215, 1215, 1211, 1130, 1119, 1128, 1126, 1135, 1022,
+ /*   310 */  1060, 1286, 1286, 1282, 1282, 1282, 1282, 1329, 1329, 1267,
+ /*   320 */  1298, 1298, 1044, 1044, 1298, 1332, 1332, 1332, 1332, 1332,
+ /*   330 */  1332, 1293, 1332, 1220, 1332, 1332, 1332, 1332, 1332, 1332,
+ /*   340 */  1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332,
+ /*   350 */  1332, 1332, 1152, 1332, 1000, 1264, 1332, 1332, 1263, 1332,
+ /*   360 */  1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332,
+ /*   370 */  1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1320,
+ /*   380 */  1332, 1332, 1332, 1332, 1332, 1332, 1235, 1234, 1332, 1332,
+ /*   390 */  1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332,
+ /*   400 */  1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332,
+ /*   410 */  1332, 1082, 1332, 1332, 1332, 1307, 1332, 1332, 1332, 1332,
+ /*   420 */  1332, 1332, 1332, 1127, 1332, 1120, 1332, 1332, 1311, 1332,
+ /*   430 */  1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1332, 1273,
+ /*   440 */  1332, 1332, 1332, 1272, 1332, 1332, 1332, 1332, 1332, 1154,
+ /*   450 */  1332, 1153, 1157, 1332, 1010, 1332,
+};
+/********** End of lemon-generated parsing tables *****************************/
+
+/* The next table maps tokens (terminal symbols) into fallback tokens.  
+** If a construct like the following:
+** 
+**      %fallback ID X Y Z.
+**
+** appears in the grammar, then ID becomes a fallback token for X, Y,
+** and Z.  Whenever one of the tokens X, Y, or Z is input to the parser
+** but it does not parse, the type of the token is changed to ID and
+** the parse is retried before an error is thrown.
+**
+** This feature can be used, for example, to cause some keywords in a language
+** to revert to identifiers if they keyword does not apply in the context where
+** it appears.
+*/
+#ifdef YYFALLBACK
+static const YYCODETYPE yyFallback[] = {
+    0,  /*          $ => nothing */
+    0,  /*       SEMI => nothing */
+   55,  /*    EXPLAIN => ID */
+   55,  /*      QUERY => ID */
+   55,  /*       PLAN => ID */
+   55,  /*      BEGIN => ID */
+    0,  /* TRANSACTION => nothing */
+   55,  /*   DEFERRED => ID */
+   55,  /*  IMMEDIATE => ID */
+   55,  /*  EXCLUSIVE => ID */
+    0,  /*     COMMIT => nothing */
+   55,  /*        END => ID */
+   55,  /*   ROLLBACK => ID */
+   55,  /*  SAVEPOINT => ID */
+   55,  /*    RELEASE => ID */
+    0,  /*         TO => nothing */
+    0,  /*      TABLE => nothing */
+    0,  /*     CREATE => nothing */
+   55,  /*         IF => ID */
+    0,  /*        NOT => nothing */
+    0,  /*     EXISTS => nothing */
+   55,  /*       TEMP => ID */
+    0,  /*         LP => nothing */
+    0,  /*         RP => nothing */
+    0,  /*         AS => nothing */
+   55,  /*    WITHOUT => ID */
+    0,  /*      COMMA => nothing */
+    0,  /*         OR => nothing */
+    0,  /*        AND => nothing */
+    0,  /*         IS => nothing */
+   55,  /*      MATCH => ID */
+   55,  /*    LIKE_KW => ID */
+    0,  /*    BETWEEN => nothing */
+    0,  /*         IN => nothing */
+    0,  /*     ISNULL => nothing */
+    0,  /*    NOTNULL => nothing */
+    0,  /*         NE => nothing */
+    0,  /*         EQ => nothing */
+    0,  /*         GT => nothing */
+    0,  /*         LE => nothing */
+    0,  /*         LT => nothing */
+    0,  /*         GE => nothing */
+    0,  /*     ESCAPE => nothing */
+    0,  /*     BITAND => nothing */
+    0,  /*      BITOR => nothing */
+    0,  /*     LSHIFT => nothing */
+    0,  /*     RSHIFT => nothing */
+    0,  /*       PLUS => nothing */
+    0,  /*      MINUS => nothing */
+    0,  /*       STAR => nothing */
+    0,  /*      SLASH => nothing */
+    0,  /*        REM => nothing */
+    0,  /*     CONCAT => nothing */
+    0,  /*    COLLATE => nothing */
+    0,  /*     BITNOT => nothing */
+    0,  /*         ID => nothing */
+    0,  /*    INDEXED => nothing */
+   55,  /*      ABORT => ID */
+   55,  /*     ACTION => ID */
+   55,  /*      AFTER => ID */
+   55,  /*    ANALYZE => ID */
+   55,  /*        ASC => ID */
+   55,  /*     ATTACH => ID */
+   55,  /*     BEFORE => ID */
+   55,  /*         BY => ID */
+   55,  /*    CASCADE => ID */
+   55,  /*       CAST => ID */
+   55,  /*   COLUMNKW => ID */
+   55,  /*   CONFLICT => ID */
+   55,  /*   DATABASE => ID */
+   55,  /*       DESC => ID */
+   55,  /*     DETACH => ID */
+   55,  /*       EACH => ID */
+   55,  /*       FAIL => ID */
+   55,  /*        FOR => ID */
+   55,  /*     IGNORE => ID */
+   55,  /*  INITIALLY => ID */
+   55,  /*    INSTEAD => ID */
+   55,  /*         NO => ID */
+   55,  /*        KEY => ID */
+   55,  /*         OF => ID */
+   55,  /*     OFFSET => ID */
+   55,  /*     PRAGMA => ID */
+   55,  /*      RAISE => ID */
+   55,  /*  RECURSIVE => ID */
+   55,  /*    REPLACE => ID */
+   55,  /*   RESTRICT => ID */
+   55,  /*        ROW => ID */
+   55,  /*    TRIGGER => ID */
+   55,  /*     VACUUM => ID */
+   55,  /*       VIEW => ID */
+   55,  /*    VIRTUAL => ID */
+   55,  /*       WITH => ID */
+   55,  /*    REINDEX => ID */
+   55,  /*     RENAME => ID */
+   55,  /*   CTIME_KW => ID */
+};
+#endif /* YYFALLBACK */
+
+/* The following structure represents a single element of the
+** parser's stack.  Information stored includes:
+**
+**   +  The state number for the parser at this level of the stack.
+**
+**   +  The value of the token stored at this level of the stack.
+**      (In other words, the "major" token.)
+**
+**   +  The semantic value stored at this level of the stack.  This is
+**      the information used by the action routines in the grammar.
+**      It is sometimes called the "minor" token.
+**
+** After the "shift" half of a SHIFTREDUCE action, the stateno field
+** actually contains the reduce action for the second half of the
+** SHIFTREDUCE.
+*/
+struct yyStackEntry {
+  YYACTIONTYPE stateno;  /* The state-number, or reduce action in SHIFTREDUCE */
+  YYCODETYPE major;      /* The major token value.  This is the code
+                         ** number for the token at this stack level */
+  YYMINORTYPE minor;     /* The user-supplied minor token value.  This
+                         ** is the value of the token  */
+};
+typedef struct yyStackEntry yyStackEntry;
+
+/* The state of the parser is completely contained in an instance of
+** the following structure */
+struct yyParser {
+  yyStackEntry *yytos;          /* Pointer to top element of the stack */
+#ifdef YYTRACKMAXSTACKDEPTH
+  int yyhwm;                    /* High-water mark of the stack */
+#endif
+#ifndef YYNOERRORRECOVERY
+  int yyerrcnt;                 /* Shifts left before out of the error */
+#endif
+  sqlite3ParserARG_SDECL                /* A place to hold %extra_argument */
+#if YYSTACKDEPTH<=0
+  int yystksz;                  /* Current side of the stack */
+  yyStackEntry *yystack;        /* The parser's stack */
+  yyStackEntry yystk0;          /* First stack entry */
+#else
+  yyStackEntry yystack[YYSTACKDEPTH];  /* The parser's stack */
+#endif
+};
+typedef struct yyParser yyParser;
+
+#ifndef NDEBUG
+/* #include <stdio.h> */
+static FILE *yyTraceFILE = 0;
+static char *yyTracePrompt = 0;
+#endif /* NDEBUG */
+
+#ifndef NDEBUG
+/* 
+** Turn parser tracing on by giving a stream to which to write the trace
+** and a prompt to preface each trace message.  Tracing is turned off
+** by making either argument NULL 
+**
+** Inputs:
+** <ul>
+** <li> A FILE* to which trace output should be written.
+**      If NULL, then tracing is turned off.
+** <li> A prefix string written at the beginning of every
+**      line of trace output.  If NULL, then tracing is
+**      turned off.
+** </ul>
+**
+** Outputs:
+** None.
+*/
+SQLITE_PRIVATE void sqlite3ParserTrace(FILE *TraceFILE, char *zTracePrompt){
+  yyTraceFILE = TraceFILE;
+  yyTracePrompt = zTracePrompt;
+  if( yyTraceFILE==0 ) yyTracePrompt = 0;
+  else if( yyTracePrompt==0 ) yyTraceFILE = 0;
+}
+#endif /* NDEBUG */
+
+#ifndef NDEBUG
+/* For tracing shifts, the names of all terminals and nonterminals
+** are required.  The following table supplies these names */
+static const char *const yyTokenName[] = { 
+  "$",             "SEMI",          "EXPLAIN",       "QUERY",       
+  "PLAN",          "BEGIN",         "TRANSACTION",   "DEFERRED",    
+  "IMMEDIATE",     "EXCLUSIVE",     "COMMIT",        "END",         
+  "ROLLBACK",      "SAVEPOINT",     "RELEASE",       "TO",          
+  "TABLE",         "CREATE",        "IF",            "NOT",         
+  "EXISTS",        "TEMP",          "LP",            "RP",          
+  "AS",            "WITHOUT",       "COMMA",         "OR",          
+  "AND",           "IS",            "MATCH",         "LIKE_KW",     
+  "BETWEEN",       "IN",            "ISNULL",        "NOTNULL",     
+  "NE",            "EQ",            "GT",            "LE",          
+  "LT",            "GE",            "ESCAPE",        "BITAND",      
+  "BITOR",         "LSHIFT",        "RSHIFT",        "PLUS",        
+  "MINUS",         "STAR",          "SLASH",         "REM",         
+  "CONCAT",        "COLLATE",       "BITNOT",        "ID",          
+  "INDEXED",       "ABORT",         "ACTION",        "AFTER",       
+  "ANALYZE",       "ASC",           "ATTACH",        "BEFORE",      
+  "BY",            "CASCADE",       "CAST",          "COLUMNKW",    
+  "CONFLICT",      "DATABASE",      "DESC",          "DETACH",      
+  "EACH",          "FAIL",          "FOR",           "IGNORE",      
+  "INITIALLY",     "INSTEAD",       "NO",            "KEY",         
+  "OF",            "OFFSET",        "PRAGMA",        "RAISE",       
+  "RECURSIVE",     "REPLACE",       "RESTRICT",      "ROW",         
+  "TRIGGER",       "VACUUM",        "VIEW",          "VIRTUAL",     
+  "WITH",          "REINDEX",       "RENAME",        "CTIME_KW",    
+  "ANY",           "STRING",        "JOIN_KW",       "CONSTRAINT",  
+  "DEFAULT",       "NULL",          "PRIMARY",       "UNIQUE",      
+  "CHECK",         "REFERENCES",    "AUTOINCR",      "ON",          
+  "INSERT",        "DELETE",        "UPDATE",        "SET",         
+  "DEFERRABLE",    "FOREIGN",       "DROP",          "UNION",       
+  "ALL",           "EXCEPT",        "INTERSECT",     "SELECT",      
+  "VALUES",        "DISTINCT",      "DOT",           "FROM",        
+  "JOIN",          "USING",         "ORDER",         "GROUP",       
+  "HAVING",        "LIMIT",         "WHERE",         "INTO",        
+  "FLOAT",         "BLOB",          "INTEGER",       "VARIABLE",    
+  "CASE",          "WHEN",          "THEN",          "ELSE",        
+  "INDEX",         "ALTER",         "ADD",           "error",       
+  "input",         "cmdlist",       "ecmd",          "explain",     
+  "cmdx",          "cmd",           "transtype",     "trans_opt",   
+  "nm",            "savepoint_opt",  "create_table",  "create_table_args",
+  "createkw",      "temp",          "ifnotexists",   "dbnm",        
+  "columnlist",    "conslist_opt",  "table_options",  "select",      
+  "columnname",    "carglist",      "typetoken",     "typename",    
+  "signed",        "plus_num",      "minus_num",     "ccons",       
+  "term",          "expr",          "onconf",        "sortorder",   
+  "autoinc",       "eidlist_opt",   "refargs",       "defer_subclause",
+  "refarg",        "refact",        "init_deferred_pred_opt",  "conslist",    
+  "tconscomma",    "tcons",         "sortlist",      "eidlist",     
+  "defer_subclause_opt",  "orconf",        "resolvetype",   "raisetype",   
+  "ifexists",      "fullname",      "selectnowith",  "oneselect",   
+  "with",          "multiselect_op",  "distinct",      "selcollist",  
+  "from",          "where_opt",     "groupby_opt",   "having_opt",  
+  "orderby_opt",   "limit_opt",     "values",        "nexprlist",   
+  "exprlist",      "sclp",          "as",            "seltablist",  
+  "stl_prefix",    "joinop",        "indexed_opt",   "on_opt",      
+  "using_opt",     "idlist",        "setlist",       "insert_cmd",  
+  "idlist_opt",    "likeop",        "between_op",    "in_op",       
+  "paren_exprlist",  "case_operand",  "case_exprlist",  "case_else",   
+  "uniqueflag",    "collate",       "nmnum",         "trigger_decl",
+  "trigger_cmd_list",  "trigger_time",  "trigger_event",  "foreach_clause",
+  "when_clause",   "trigger_cmd",   "trnm",          "tridxby",     
+  "database_kw_opt",  "key_opt",       "add_column_fullname",  "kwcolumn_opt",
+  "create_vtab",   "vtabarglist",   "vtabarg",       "vtabargtoken",
+  "lp",            "anylist",       "wqlist",      
+};
+#endif /* NDEBUG */
+
+#ifndef NDEBUG
+/* For tracing reduce actions, the names of all rules are required.
+*/
+static const char *const yyRuleName[] = {
+ /*   0 */ "explain ::= EXPLAIN",
+ /*   1 */ "explain ::= EXPLAIN QUERY PLAN",
+ /*   2 */ "cmdx ::= cmd",
+ /*   3 */ "cmd ::= BEGIN transtype trans_opt",
+ /*   4 */ "transtype ::=",
+ /*   5 */ "transtype ::= DEFERRED",
+ /*   6 */ "transtype ::= IMMEDIATE",
+ /*   7 */ "transtype ::= EXCLUSIVE",
+ /*   8 */ "cmd ::= COMMIT trans_opt",
+ /*   9 */ "cmd ::= END trans_opt",
+ /*  10 */ "cmd ::= ROLLBACK trans_opt",
+ /*  11 */ "cmd ::= SAVEPOINT nm",
+ /*  12 */ "cmd ::= RELEASE savepoint_opt nm",
+ /*  13 */ "cmd ::= ROLLBACK trans_opt TO savepoint_opt nm",
+ /*  14 */ "create_table ::= createkw temp TABLE ifnotexists nm dbnm",
+ /*  15 */ "createkw ::= CREATE",
+ /*  16 */ "ifnotexists ::=",
+ /*  17 */ "ifnotexists ::= IF NOT EXISTS",
+ /*  18 */ "temp ::= TEMP",
+ /*  19 */ "temp ::=",
+ /*  20 */ "create_table_args ::= LP columnlist conslist_opt RP table_options",
+ /*  21 */ "create_table_args ::= AS select",
+ /*  22 */ "table_options ::=",
+ /*  23 */ "table_options ::= WITHOUT nm",
+ /*  24 */ "columnname ::= nm typetoken",
+ /*  25 */ "typetoken ::=",
+ /*  26 */ "typetoken ::= typename LP signed RP",
+ /*  27 */ "typetoken ::= typename LP signed COMMA signed RP",
+ /*  28 */ "typename ::= typename ID|STRING",
+ /*  29 */ "ccons ::= CONSTRAINT nm",
+ /*  30 */ "ccons ::= DEFAULT term",
+ /*  31 */ "ccons ::= DEFAULT LP expr RP",
+ /*  32 */ "ccons ::= DEFAULT PLUS term",
+ /*  33 */ "ccons ::= DEFAULT MINUS term",
+ /*  34 */ "ccons ::= DEFAULT ID|INDEXED",
+ /*  35 */ "ccons ::= NOT NULL onconf",
+ /*  36 */ "ccons ::= PRIMARY KEY sortorder onconf autoinc",
+ /*  37 */ "ccons ::= UNIQUE onconf",
+ /*  38 */ "ccons ::= CHECK LP expr RP",
+ /*  39 */ "ccons ::= REFERENCES nm eidlist_opt refargs",
+ /*  40 */ "ccons ::= defer_subclause",
+ /*  41 */ "ccons ::= COLLATE ID|STRING",
+ /*  42 */ "autoinc ::=",
+ /*  43 */ "autoinc ::= AUTOINCR",
+ /*  44 */ "refargs ::=",
+ /*  45 */ "refargs ::= refargs refarg",
+ /*  46 */ "refarg ::= MATCH nm",
+ /*  47 */ "refarg ::= ON INSERT refact",
+ /*  48 */ "refarg ::= ON DELETE refact",
+ /*  49 */ "refarg ::= ON UPDATE refact",
+ /*  50 */ "refact ::= SET NULL",
+ /*  51 */ "refact ::= SET DEFAULT",
+ /*  52 */ "refact ::= CASCADE",
+ /*  53 */ "refact ::= RESTRICT",
+ /*  54 */ "refact ::= NO ACTION",
+ /*  55 */ "defer_subclause ::= NOT DEFERRABLE init_deferred_pred_opt",
+ /*  56 */ "defer_subclause ::= DEFERRABLE init_deferred_pred_opt",
+ /*  57 */ "init_deferred_pred_opt ::=",
+ /*  58 */ "init_deferred_pred_opt ::= INITIALLY DEFERRED",
+ /*  59 */ "init_deferred_pred_opt ::= INITIALLY IMMEDIATE",
+ /*  60 */ "conslist_opt ::=",
+ /*  61 */ "tconscomma ::= COMMA",
+ /*  62 */ "tcons ::= CONSTRAINT nm",
+ /*  63 */ "tcons ::= PRIMARY KEY LP sortlist autoinc RP onconf",
+ /*  64 */ "tcons ::= UNIQUE LP sortlist RP onconf",
+ /*  65 */ "tcons ::= CHECK LP expr RP onconf",
+ /*  66 */ "tcons ::= FOREIGN KEY LP eidlist RP REFERENCES nm eidlist_opt refargs defer_subclause_opt",
+ /*  67 */ "defer_subclause_opt ::=",
+ /*  68 */ "onconf ::=",
+ /*  69 */ "onconf ::= ON CONFLICT resolvetype",
+ /*  70 */ "orconf ::=",
+ /*  71 */ "orconf ::= OR resolvetype",
+ /*  72 */ "resolvetype ::= IGNORE",
+ /*  73 */ "resolvetype ::= REPLACE",
+ /*  74 */ "cmd ::= DROP TABLE ifexists fullname",
+ /*  75 */ "ifexists ::= IF EXISTS",
+ /*  76 */ "ifexists ::=",
+ /*  77 */ "cmd ::= createkw temp VIEW ifnotexists nm dbnm eidlist_opt AS select",
+ /*  78 */ "cmd ::= DROP VIEW ifexists fullname",
+ /*  79 */ "cmd ::= select",
+ /*  80 */ "select ::= with selectnowith",
+ /*  81 */ "selectnowith ::= selectnowith multiselect_op oneselect",
+ /*  82 */ "multiselect_op ::= UNION",
+ /*  83 */ "multiselect_op ::= UNION ALL",
+ /*  84 */ "multiselect_op ::= EXCEPT|INTERSECT",
+ /*  85 */ "oneselect ::= SELECT distinct selcollist from where_opt groupby_opt having_opt orderby_opt limit_opt",
+ /*  86 */ "values ::= VALUES LP nexprlist RP",
+ /*  87 */ "values ::= values COMMA LP exprlist RP",
+ /*  88 */ "distinct ::= DISTINCT",
+ /*  89 */ "distinct ::= ALL",
+ /*  90 */ "distinct ::=",
+ /*  91 */ "sclp ::=",
+ /*  92 */ "selcollist ::= sclp expr as",
+ /*  93 */ "selcollist ::= sclp STAR",
+ /*  94 */ "selcollist ::= sclp nm DOT STAR",
+ /*  95 */ "as ::= AS nm",
+ /*  96 */ "as ::=",
+ /*  97 */ "from ::=",
+ /*  98 */ "from ::= FROM seltablist",
+ /*  99 */ "stl_prefix ::= seltablist joinop",
+ /* 100 */ "stl_prefix ::=",
+ /* 101 */ "seltablist ::= stl_prefix nm dbnm as indexed_opt on_opt using_opt",
+ /* 102 */ "seltablist ::= stl_prefix nm dbnm LP exprlist RP as on_opt using_opt",
+ /* 103 */ "seltablist ::= stl_prefix LP select RP as on_opt using_opt",
+ /* 104 */ "seltablist ::= stl_prefix LP seltablist RP as on_opt using_opt",
+ /* 105 */ "dbnm ::=",
+ /* 106 */ "dbnm ::= DOT nm",
+ /* 107 */ "fullname ::= nm dbnm",
+ /* 108 */ "joinop ::= COMMA|JOIN",
+ /* 109 */ "joinop ::= JOIN_KW JOIN",
+ /* 110 */ "joinop ::= JOIN_KW nm JOIN",
+ /* 111 */ "joinop ::= JOIN_KW nm nm JOIN",
+ /* 112 */ "on_opt ::= ON expr",
+ /* 113 */ "on_opt ::=",
+ /* 114 */ "indexed_opt ::=",
+ /* 115 */ "indexed_opt ::= INDEXED BY nm",
+ /* 116 */ "indexed_opt ::= NOT INDEXED",
+ /* 117 */ "using_opt ::= USING LP idlist RP",
+ /* 118 */ "using_opt ::=",
+ /* 119 */ "orderby_opt ::=",
+ /* 120 */ "orderby_opt ::= ORDER BY sortlist",
+ /* 121 */ "sortlist ::= sortlist COMMA expr sortorder",
+ /* 122 */ "sortlist ::= expr sortorder",
+ /* 123 */ "sortorder ::= ASC",
+ /* 124 */ "sortorder ::= DESC",
+ /* 125 */ "sortorder ::=",
+ /* 126 */ "groupby_opt ::=",
+ /* 127 */ "groupby_opt ::= GROUP BY nexprlist",
+ /* 128 */ "having_opt ::=",
+ /* 129 */ "having_opt ::= HAVING expr",
+ /* 130 */ "limit_opt ::=",
+ /* 131 */ "limit_opt ::= LIMIT expr",
+ /* 132 */ "limit_opt ::= LIMIT expr OFFSET expr",
+ /* 133 */ "limit_opt ::= LIMIT expr COMMA expr",
+ /* 134 */ "cmd ::= with DELETE FROM fullname indexed_opt where_opt",
+ /* 135 */ "where_opt ::=",
+ /* 136 */ "where_opt ::= WHERE expr",
+ /* 137 */ "cmd ::= with UPDATE orconf fullname indexed_opt SET setlist where_opt",
+ /* 138 */ "setlist ::= setlist COMMA nm EQ expr",
+ /* 139 */ "setlist ::= setlist COMMA LP idlist RP EQ expr",
+ /* 140 */ "setlist ::= nm EQ expr",
+ /* 141 */ "setlist ::= LP idlist RP EQ expr",
+ /* 142 */ "cmd ::= with insert_cmd INTO fullname idlist_opt select",
+ /* 143 */ "cmd ::= with insert_cmd INTO fullname idlist_opt DEFAULT VALUES",
+ /* 144 */ "insert_cmd ::= INSERT orconf",
+ /* 145 */ "insert_cmd ::= REPLACE",
+ /* 146 */ "idlist_opt ::=",
+ /* 147 */ "idlist_opt ::= LP idlist RP",
+ /* 148 */ "idlist ::= idlist COMMA nm",
+ /* 149 */ "idlist ::= nm",
+ /* 150 */ "expr ::= LP expr RP",
+ /* 151 */ "term ::= NULL",
+ /* 152 */ "expr ::= ID|INDEXED",
+ /* 153 */ "expr ::= JOIN_KW",
+ /* 154 */ "expr ::= nm DOT nm",
+ /* 155 */ "expr ::= nm DOT nm DOT nm",
+ /* 156 */ "term ::= FLOAT|BLOB",
+ /* 157 */ "term ::= STRING",
+ /* 158 */ "term ::= INTEGER",
+ /* 159 */ "expr ::= VARIABLE",
+ /* 160 */ "expr ::= expr COLLATE ID|STRING",
+ /* 161 */ "expr ::= CAST LP expr AS typetoken RP",
+ /* 162 */ "expr ::= ID|INDEXED LP distinct exprlist RP",
+ /* 163 */ "expr ::= ID|INDEXED LP STAR RP",
+ /* 164 */ "term ::= CTIME_KW",
+ /* 165 */ "expr ::= LP nexprlist COMMA expr RP",
+ /* 166 */ "expr ::= expr AND expr",
+ /* 167 */ "expr ::= expr OR expr",
+ /* 168 */ "expr ::= expr LT|GT|GE|LE expr",
+ /* 169 */ "expr ::= expr EQ|NE expr",
+ /* 170 */ "expr ::= expr BITAND|BITOR|LSHIFT|RSHIFT expr",
+ /* 171 */ "expr ::= expr PLUS|MINUS expr",
+ /* 172 */ "expr ::= expr STAR|SLASH|REM expr",
+ /* 173 */ "expr ::= expr CONCAT expr",
+ /* 174 */ "likeop ::= LIKE_KW|MATCH",
+ /* 175 */ "likeop ::= NOT LIKE_KW|MATCH",
+ /* 176 */ "expr ::= expr likeop expr",
+ /* 177 */ "expr ::= expr likeop expr ESCAPE expr",
+ /* 178 */ "expr ::= expr ISNULL|NOTNULL",
+ /* 179 */ "expr ::= expr NOT NULL",
+ /* 180 */ "expr ::= expr IS expr",
+ /* 181 */ "expr ::= expr IS NOT expr",
+ /* 182 */ "expr ::= NOT expr",
+ /* 183 */ "expr ::= BITNOT expr",
+ /* 184 */ "expr ::= MINUS expr",
+ /* 185 */ "expr ::= PLUS expr",
+ /* 186 */ "between_op ::= BETWEEN",
+ /* 187 */ "between_op ::= NOT BETWEEN",
+ /* 188 */ "expr ::= expr between_op expr AND expr",
+ /* 189 */ "in_op ::= IN",
+ /* 190 */ "in_op ::= NOT IN",
+ /* 191 */ "expr ::= expr in_op LP exprlist RP",
+ /* 192 */ "expr ::= LP select RP",
+ /* 193 */ "expr ::= expr in_op LP select RP",
+ /* 194 */ "expr ::= expr in_op nm dbnm paren_exprlist",
+ /* 195 */ "expr ::= EXISTS LP select RP",
+ /* 196 */ "expr ::= CASE case_operand case_exprlist case_else END",
+ /* 197 */ "case_exprlist ::= case_exprlist WHEN expr THEN expr",
+ /* 198 */ "case_exprlist ::= WHEN expr THEN expr",
+ /* 199 */ "case_else ::= ELSE expr",
+ /* 200 */ "case_else ::=",
+ /* 201 */ "case_operand ::= expr",
+ /* 202 */ "case_operand ::=",
+ /* 203 */ "exprlist ::=",
+ /* 204 */ "nexprlist ::= nexprlist COMMA expr",
+ /* 205 */ "nexprlist ::= expr",
+ /* 206 */ "paren_exprlist ::=",
+ /* 207 */ "paren_exprlist ::= LP exprlist RP",
+ /* 208 */ "cmd ::= createkw uniqueflag INDEX ifnotexists nm dbnm ON nm LP sortlist RP where_opt",
+ /* 209 */ "uniqueflag ::= UNIQUE",
+ /* 210 */ "uniqueflag ::=",
+ /* 211 */ "eidlist_opt ::=",
+ /* 212 */ "eidlist_opt ::= LP eidlist RP",
+ /* 213 */ "eidlist ::= eidlist COMMA nm collate sortorder",
+ /* 214 */ "eidlist ::= nm collate sortorder",
+ /* 215 */ "collate ::=",
+ /* 216 */ "collate ::= COLLATE ID|STRING",
+ /* 217 */ "cmd ::= DROP INDEX ifexists fullname",
+ /* 218 */ "cmd ::= VACUUM",
+ /* 219 */ "cmd ::= VACUUM nm",
+ /* 220 */ "cmd ::= PRAGMA nm dbnm",
+ /* 221 */ "cmd ::= PRAGMA nm dbnm EQ nmnum",
+ /* 222 */ "cmd ::= PRAGMA nm dbnm LP nmnum RP",
+ /* 223 */ "cmd ::= PRAGMA nm dbnm EQ minus_num",
+ /* 224 */ "cmd ::= PRAGMA nm dbnm LP minus_num RP",
+ /* 225 */ "plus_num ::= PLUS INTEGER|FLOAT",
+ /* 226 */ "minus_num ::= MINUS INTEGER|FLOAT",
+ /* 227 */ "cmd ::= createkw trigger_decl BEGIN trigger_cmd_list END",
+ /* 228 */ "trigger_decl ::= temp TRIGGER ifnotexists nm dbnm trigger_time trigger_event ON fullname foreach_clause when_clause",
+ /* 229 */ "trigger_time ::= BEFORE",
+ /* 230 */ "trigger_time ::= AFTER",
+ /* 231 */ "trigger_time ::= INSTEAD OF",
+ /* 232 */ "trigger_time ::=",
+ /* 233 */ "trigger_event ::= DELETE|INSERT",
+ /* 234 */ "trigger_event ::= UPDATE",
+ /* 235 */ "trigger_event ::= UPDATE OF idlist",
+ /* 236 */ "when_clause ::=",
+ /* 237 */ "when_clause ::= WHEN expr",
+ /* 238 */ "trigger_cmd_list ::= trigger_cmd_list trigger_cmd SEMI",
+ /* 239 */ "trigger_cmd_list ::= trigger_cmd SEMI",
+ /* 240 */ "trnm ::= nm DOT nm",
+ /* 241 */ "tridxby ::= INDEXED BY nm",
+ /* 242 */ "tridxby ::= NOT INDEXED",
+ /* 243 */ "trigger_cmd ::= UPDATE orconf trnm tridxby SET setlist where_opt",
+ /* 244 */ "trigger_cmd ::= insert_cmd INTO trnm idlist_opt select",
+ /* 245 */ "trigger_cmd ::= DELETE FROM trnm tridxby where_opt",
+ /* 246 */ "trigger_cmd ::= select",
+ /* 247 */ "expr ::= RAISE LP IGNORE RP",
+ /* 248 */ "expr ::= RAISE LP raisetype COMMA nm RP",
+ /* 249 */ "raisetype ::= ROLLBACK",
+ /* 250 */ "raisetype ::= ABORT",
+ /* 251 */ "raisetype ::= FAIL",
+ /* 252 */ "cmd ::= DROP TRIGGER ifexists fullname",
+ /* 253 */ "cmd ::= ATTACH database_kw_opt expr AS expr key_opt",
+ /* 254 */ "cmd ::= DETACH database_kw_opt expr",
+ /* 255 */ "key_opt ::=",
+ /* 256 */ "key_opt ::= KEY expr",
+ /* 257 */ "cmd ::= REINDEX",
+ /* 258 */ "cmd ::= REINDEX nm dbnm",
+ /* 259 */ "cmd ::= ANALYZE",
+ /* 260 */ "cmd ::= ANALYZE nm dbnm",
+ /* 261 */ "cmd ::= ALTER TABLE fullname RENAME TO nm",
+ /* 262 */ "cmd ::= ALTER TABLE add_column_fullname ADD kwcolumn_opt columnname carglist",
+ /* 263 */ "add_column_fullname ::= fullname",
+ /* 264 */ "cmd ::= create_vtab",
+ /* 265 */ "cmd ::= create_vtab LP vtabarglist RP",
+ /* 266 */ "create_vtab ::= createkw VIRTUAL TABLE ifnotexists nm dbnm USING nm",
+ /* 267 */ "vtabarg ::=",
+ /* 268 */ "vtabargtoken ::= ANY",
+ /* 269 */ "vtabargtoken ::= lp anylist RP",
+ /* 270 */ "lp ::= LP",
+ /* 271 */ "with ::=",
+ /* 272 */ "with ::= WITH wqlist",
+ /* 273 */ "with ::= WITH RECURSIVE wqlist",
+ /* 274 */ "wqlist ::= nm eidlist_opt AS LP select RP",
+ /* 275 */ "wqlist ::= wqlist COMMA nm eidlist_opt AS LP select RP",
+ /* 276 */ "input ::= cmdlist",
+ /* 277 */ "cmdlist ::= cmdlist ecmd",
+ /* 278 */ "cmdlist ::= ecmd",
+ /* 279 */ "ecmd ::= SEMI",
+ /* 280 */ "ecmd ::= explain cmdx SEMI",
+ /* 281 */ "explain ::=",
+ /* 282 */ "trans_opt ::=",
+ /* 283 */ "trans_opt ::= TRANSACTION",
+ /* 284 */ "trans_opt ::= TRANSACTION nm",
+ /* 285 */ "savepoint_opt ::= SAVEPOINT",
+ /* 286 */ "savepoint_opt ::=",
+ /* 287 */ "cmd ::= create_table create_table_args",
+ /* 288 */ "columnlist ::= columnlist COMMA columnname carglist",
+ /* 289 */ "columnlist ::= columnname carglist",
+ /* 290 */ "nm ::= ID|INDEXED",
+ /* 291 */ "nm ::= STRING",
+ /* 292 */ "nm ::= JOIN_KW",
+ /* 293 */ "typetoken ::= typename",
+ /* 294 */ "typename ::= ID|STRING",
+ /* 295 */ "signed ::= plus_num",
+ /* 296 */ "signed ::= minus_num",
+ /* 297 */ "carglist ::= carglist ccons",
+ /* 298 */ "carglist ::=",
+ /* 299 */ "ccons ::= NULL onconf",
+ /* 300 */ "conslist_opt ::= COMMA conslist",
+ /* 301 */ "conslist ::= conslist tconscomma tcons",
+ /* 302 */ "conslist ::= tcons",
+ /* 303 */ "tconscomma ::=",
+ /* 304 */ "defer_subclause_opt ::= defer_subclause",
+ /* 305 */ "resolvetype ::= raisetype",
+ /* 306 */ "selectnowith ::= oneselect",
+ /* 307 */ "oneselect ::= values",
+ /* 308 */ "sclp ::= selcollist COMMA",
+ /* 309 */ "as ::= ID|STRING",
+ /* 310 */ "expr ::= term",
+ /* 311 */ "exprlist ::= nexprlist",
+ /* 312 */ "nmnum ::= plus_num",
+ /* 313 */ "nmnum ::= nm",
+ /* 314 */ "nmnum ::= ON",
+ /* 315 */ "nmnum ::= DELETE",
+ /* 316 */ "nmnum ::= DEFAULT",
+ /* 317 */ "plus_num ::= INTEGER|FLOAT",
+ /* 318 */ "foreach_clause ::=",
+ /* 319 */ "foreach_clause ::= FOR EACH ROW",
+ /* 320 */ "trnm ::= nm",
+ /* 321 */ "tridxby ::=",
+ /* 322 */ "database_kw_opt ::= DATABASE",
+ /* 323 */ "database_kw_opt ::=",
+ /* 324 */ "kwcolumn_opt ::=",
+ /* 325 */ "kwcolumn_opt ::= COLUMNKW",
+ /* 326 */ "vtabarglist ::= vtabarg",
+ /* 327 */ "vtabarglist ::= vtabarglist COMMA vtabarg",
+ /* 328 */ "vtabarg ::= vtabarg vtabargtoken",
+ /* 329 */ "anylist ::=",
+ /* 330 */ "anylist ::= anylist LP anylist RP",
+ /* 331 */ "anylist ::= anylist ANY",
+};
+#endif /* NDEBUG */
+
+
+#if YYSTACKDEPTH<=0
+/*
+** Try to increase the size of the parser stack.  Return the number
+** of errors.  Return 0 on success.
+*/
+static int yyGrowStack(yyParser *p){
+  int newSize;
+  int idx;
+  yyStackEntry *pNew;
+
+  newSize = p->yystksz*2 + 100;
+  idx = p->yytos ? (int)(p->yytos - p->yystack) : 0;
+  if( p->yystack==&p->yystk0 ){
+    pNew = malloc(newSize*sizeof(pNew[0]));
+    if( pNew ) pNew[0] = p->yystk0;
+  }else{
+    pNew = realloc(p->yystack, newSize*sizeof(pNew[0]));
+  }
+  if( pNew ){
+    p->yystack = pNew;
+    p->yytos = &p->yystack[idx];
+#ifndef NDEBUG
+    if( yyTraceFILE ){
+      fprintf(yyTraceFILE,"%sStack grows from %d to %d entries.\n",
+              yyTracePrompt, p->yystksz, newSize);
+    }
+#endif
+    p->yystksz = newSize;
+  }
+  return pNew==0; 
+}
+#endif
+
+/* Datatype of the argument to the memory allocated passed as the
+** second argument to sqlite3ParserAlloc() below.  This can be changed by
+** putting an appropriate #define in the %include section of the input
+** grammar.
+*/
+#ifndef YYMALLOCARGTYPE
+# define YYMALLOCARGTYPE size_t
+#endif
+
+/* 
+** This function allocates a new parser.
+** The only argument is a pointer to a function which works like
+** malloc.
+**
+** Inputs:
+** A pointer to the function used to allocate memory.
+**
+** Outputs:
+** A pointer to a parser.  This pointer is used in subsequent calls
+** to sqlite3Parser and sqlite3ParserFree.
+*/
+SQLITE_PRIVATE void *sqlite3ParserAlloc(void *(*mallocProc)(YYMALLOCARGTYPE)){
+  yyParser *pParser;
+  pParser = (yyParser*)(*mallocProc)( (YYMALLOCARGTYPE)sizeof(yyParser) );
+  if( pParser ){
+#ifdef YYTRACKMAXSTACKDEPTH
+    pParser->yyhwm = 0;
+#endif
+#if YYSTACKDEPTH<=0
+    pParser->yytos = NULL;
+    pParser->yystack = NULL;
+    pParser->yystksz = 0;
+    if( yyGrowStack(pParser) ){
+      pParser->yystack = &pParser->yystk0;
+      pParser->yystksz = 1;
+    }
+#endif
+#ifndef YYNOERRORRECOVERY
+    pParser->yyerrcnt = -1;
+#endif
+    pParser->yytos = pParser->yystack;
+    pParser->yystack[0].stateno = 0;
+    pParser->yystack[0].major = 0;
+  }
+  return pParser;
+}
+
+/* The following function deletes the "minor type" or semantic value
+** associated with a symbol.  The symbol can be either a terminal
+** or nonterminal. "yymajor" is the symbol code, and "yypminor" is
+** a pointer to the value to be deleted.  The code used to do the 
+** deletions is derived from the %destructor and/or %token_destructor
+** directives of the input grammar.
+*/
+static void yy_destructor(
+  yyParser *yypParser,    /* The parser */
+  YYCODETYPE yymajor,     /* Type code for object to destroy */
+  YYMINORTYPE *yypminor   /* The object to be destroyed */
+){
+  sqlite3ParserARG_FETCH;
+  switch( yymajor ){
+    /* Here is inserted the actions which take place when a
+    ** terminal or non-terminal is destroyed.  This can happen
+    ** when the symbol is popped from the stack during a
+    ** reduce or during error processing or when a parser is 
+    ** being destroyed before it is finished parsing.
+    **
+    ** Note: during a reduce, the only symbols destroyed are those
+    ** which appear on the RHS of the rule, but which are *not* used
+    ** inside the C code.
+    */
+/********* Begin destructor definitions ***************************************/
+    case 163: /* select */
+    case 194: /* selectnowith */
+    case 195: /* oneselect */
+    case 206: /* values */
+{
+sqlite3SelectDelete(pParse->db, (yypminor->yy243));
+}
+      break;
+    case 172: /* term */
+    case 173: /* expr */
+{
+sqlite3ExprDelete(pParse->db, (yypminor->yy190).pExpr);
+}
+      break;
+    case 177: /* eidlist_opt */
+    case 186: /* sortlist */
+    case 187: /* eidlist */
+    case 199: /* selcollist */
+    case 202: /* groupby_opt */
+    case 204: /* orderby_opt */
+    case 207: /* nexprlist */
+    case 208: /* exprlist */
+    case 209: /* sclp */
+    case 218: /* setlist */
+    case 224: /* paren_exprlist */
+    case 226: /* case_exprlist */
+{
+sqlite3ExprListDelete(pParse->db, (yypminor->yy148));
+}
+      break;
+    case 193: /* fullname */
+    case 200: /* from */
+    case 211: /* seltablist */
+    case 212: /* stl_prefix */
+{
+sqlite3SrcListDelete(pParse->db, (yypminor->yy185));
+}
+      break;
+    case 196: /* with */
+    case 250: /* wqlist */
+{
+sqlite3WithDelete(pParse->db, (yypminor->yy285));
+}
+      break;
+    case 201: /* where_opt */
+    case 203: /* having_opt */
+    case 215: /* on_opt */
+    case 225: /* case_operand */
+    case 227: /* case_else */
+    case 236: /* when_clause */
+    case 241: /* key_opt */
+{
+sqlite3ExprDelete(pParse->db, (yypminor->yy72));
+}
+      break;
+    case 216: /* using_opt */
+    case 217: /* idlist */
+    case 220: /* idlist_opt */
+{
+sqlite3IdListDelete(pParse->db, (yypminor->yy254));
+}
+      break;
+    case 232: /* trigger_cmd_list */
+    case 237: /* trigger_cmd */
+{
+sqlite3DeleteTriggerStep(pParse->db, (yypminor->yy145));
+}
+      break;
+    case 234: /* trigger_event */
+{
+sqlite3IdListDelete(pParse->db, (yypminor->yy332).b);
+}
+      break;
+/********* End destructor definitions *****************************************/
+    default:  break;   /* If no destructor action specified: do nothing */
+  }
+}
+
+/*
+** Pop the parser's stack once.
+**
+** If there is a destructor routine associated with the token which
+** is popped from the stack, then call it.
+*/
+static void yy_pop_parser_stack(yyParser *pParser){
+  yyStackEntry *yytos;
+  assert( pParser->yytos!=0 );
+  assert( pParser->yytos > pParser->yystack );
+  yytos = pParser->yytos--;
+#ifndef NDEBUG
+  if( yyTraceFILE ){
+    fprintf(yyTraceFILE,"%sPopping %s\n",
+      yyTracePrompt,
+      yyTokenName[yytos->major]);
+  }
+#endif
+  yy_destructor(pParser, yytos->major, &yytos->minor);
+}
+
+/* 
+** Deallocate and destroy a parser.  Destructors are called for
+** all stack elements before shutting the parser down.
+**
+** If the YYPARSEFREENEVERNULL macro exists (for example because it
+** is defined in a %include section of the input grammar) then it is
+** assumed that the input pointer is never NULL.
+*/
+SQLITE_PRIVATE void sqlite3ParserFree(
+  void *p,                    /* The parser to be deleted */
+  void (*freeProc)(void*)     /* Function used to reclaim memory */
+){
+  yyParser *pParser = (yyParser*)p;
+#ifndef YYPARSEFREENEVERNULL
+  if( pParser==0 ) return;
+#endif
+  while( pParser->yytos>pParser->yystack ) yy_pop_parser_stack(pParser);
+#if YYSTACKDEPTH<=0
+  if( pParser->yystack!=&pParser->yystk0 ) free(pParser->yystack);
+#endif
+  (*freeProc)((void*)pParser);
+}
+
+/*
+** Return the peak depth of the stack for a parser.
+*/
+#ifdef YYTRACKMAXSTACKDEPTH
+SQLITE_PRIVATE int sqlite3ParserStackPeak(void *p){
+  yyParser *pParser = (yyParser*)p;
+  return pParser->yyhwm;
+}
+#endif
+
+/*
+** Find the appropriate action for a parser given the terminal
+** look-ahead token iLookAhead.
+*/
+static unsigned int yy_find_shift_action(
+  yyParser *pParser,        /* The parser */
+  YYCODETYPE iLookAhead     /* The look-ahead token */
+){
+  int i;
+  int stateno = pParser->yytos->stateno;
+ 
+  if( stateno>=YY_MIN_REDUCE ) return stateno;
+  assert( stateno <= YY_SHIFT_COUNT );
+  do{
+    i = yy_shift_ofst[stateno];
+    assert( iLookAhead!=YYNOCODE );
+    i += iLookAhead;
+    if( i<0 || i>=YY_ACTTAB_COUNT || yy_lookahead[i]!=iLookAhead ){
+#ifdef YYFALLBACK
+      YYCODETYPE iFallback;            /* Fallback token */
+      if( iLookAhead<sizeof(yyFallback)/sizeof(yyFallback[0])
+             && (iFallback = yyFallback[iLookAhead])!=0 ){
+#ifndef NDEBUG
+        if( yyTraceFILE ){
+          fprintf(yyTraceFILE, "%sFALLBACK %s => %s\n",
+             yyTracePrompt, yyTokenName[iLookAhead], yyTokenName[iFallback]);
+        }
+#endif
+        assert( yyFallback[iFallback]==0 ); /* Fallback loop must terminate */
+        iLookAhead = iFallback;
+        continue;
+      }
+#endif
+#ifdef YYWILDCARD
+      {
+        int j = i - iLookAhead + YYWILDCARD;
+        if( 
+#if YY_SHIFT_MIN+YYWILDCARD<0
+          j>=0 &&
+#endif
+#if YY_SHIFT_MAX+YYWILDCARD>=YY_ACTTAB_COUNT
+          j<YY_ACTTAB_COUNT &&
+#endif
+          yy_lookahead[j]==YYWILDCARD && iLookAhead>0
+        ){
+#ifndef NDEBUG
+          if( yyTraceFILE ){
+            fprintf(yyTraceFILE, "%sWILDCARD %s => %s\n",
+               yyTracePrompt, yyTokenName[iLookAhead],
+               yyTokenName[YYWILDCARD]);
+          }
+#endif /* NDEBUG */
+          return yy_action[j];
+        }
+      }
+#endif /* YYWILDCARD */
+      return yy_default[stateno];
+    }else{
+      return yy_action[i];
+    }
+  }while(1);
+}
+
+/*
+** Find the appropriate action for a parser given the non-terminal
+** look-ahead token iLookAhead.
+*/
+static int yy_find_reduce_action(
+  int stateno,              /* Current state number */
+  YYCODETYPE iLookAhead     /* The look-ahead token */
+){
+  int i;
+#ifdef YYERRORSYMBOL
+  if( stateno>YY_REDUCE_COUNT ){
+    return yy_default[stateno];
+  }
+#else
+  assert( stateno<=YY_REDUCE_COUNT );
+#endif
+  i = yy_reduce_ofst[stateno];
+  assert( i!=YY_REDUCE_USE_DFLT );
+  assert( iLookAhead!=YYNOCODE );
+  i += iLookAhead;
+#ifdef YYERRORSYMBOL
+  if( i<0 || i>=YY_ACTTAB_COUNT || yy_lookahead[i]!=iLookAhead ){
+    return yy_default[stateno];
+  }
+#else
+  assert( i>=0 && i<YY_ACTTAB_COUNT );
+  assert( yy_lookahead[i]==iLookAhead );
+#endif
+  return yy_action[i];
+}
+
+/*
+** The following routine is called if the stack overflows.
+*/
+static void yyStackOverflow(yyParser *yypParser){
+   sqlite3ParserARG_FETCH;
+   yypParser->yytos--;
+#ifndef NDEBUG
+   if( yyTraceFILE ){
+     fprintf(yyTraceFILE,"%sStack Overflow!\n",yyTracePrompt);
+   }
+#endif
+   while( yypParser->yytos>yypParser->yystack ) yy_pop_parser_stack(yypParser);
+   /* Here code is inserted which will execute if the parser
+   ** stack every overflows */
+/******** Begin %stack_overflow code ******************************************/
+
+  sqlite3ErrorMsg(pParse, "parser stack overflow");
+/******** End %stack_overflow code ********************************************/
+   sqlite3ParserARG_STORE; /* Suppress warning about unused %extra_argument var */
+}
+
+/*
+** Print tracing information for a SHIFT action
+*/
+#ifndef NDEBUG
+static void yyTraceShift(yyParser *yypParser, int yyNewState){
+  if( yyTraceFILE ){
+    if( yyNewState<YYNSTATE ){
+      fprintf(yyTraceFILE,"%sShift '%s', go to state %d\n",
+         yyTracePrompt,yyTokenName[yypParser->yytos->major],
+         yyNewState);
+    }else{
+      fprintf(yyTraceFILE,"%sShift '%s'\n",
+         yyTracePrompt,yyTokenName[yypParser->yytos->major]);
+    }
+  }
+}
+#else
+# define yyTraceShift(X,Y)
+#endif
+
+/*
+** Perform a shift action.
+*/
+static void yy_shift(
+  yyParser *yypParser,          /* The parser to be shifted */
+  int yyNewState,               /* The new state to shift in */
+  int yyMajor,                  /* The major token to shift in */
+  sqlite3ParserTOKENTYPE yyMinor        /* The minor token to shift in */
+){
+  yyStackEntry *yytos;
+  yypParser->yytos++;
+#ifdef YYTRACKMAXSTACKDEPTH
+  if( (int)(yypParser->yytos - yypParser->yystack)>yypParser->yyhwm ){
+    yypParser->yyhwm++;
+    assert( yypParser->yyhwm == (int)(yypParser->yytos - yypParser->yystack) );
+  }
+#endif
+#if YYSTACKDEPTH>0 
+  if( yypParser->yytos>=&yypParser->yystack[YYSTACKDEPTH] ){
+    yyStackOverflow(yypParser);
+    return;
+  }
+#else
+  if( yypParser->yytos>=&yypParser->yystack[yypParser->yystksz] ){
+    if( yyGrowStack(yypParser) ){
+      yyStackOverflow(yypParser);
+      return;
+    }
+  }
+#endif
+  if( yyNewState > YY_MAX_SHIFT ){
+    yyNewState += YY_MIN_REDUCE - YY_MIN_SHIFTREDUCE;
+  }
+  yytos = yypParser->yytos;
+  yytos->stateno = (YYACTIONTYPE)yyNewState;
+  yytos->major = (YYCODETYPE)yyMajor;
+  yytos->minor.yy0 = yyMinor;
+  yyTraceShift(yypParser, yyNewState);
+}
+
+/* The following table contains information about every rule that
+** is used during the reduce.
+*/
+static const struct {
+  YYCODETYPE lhs;         /* Symbol on the left-hand side of the rule */
+  unsigned char nrhs;     /* Number of right-hand side symbols in the rule */
+} yyRuleInfo[] = {
+  { 147, 1 },
+  { 147, 3 },
+  { 148, 1 },
+  { 149, 3 },
+  { 150, 0 },
+  { 150, 1 },
+  { 150, 1 },
+  { 150, 1 },
+  { 149, 2 },
+  { 149, 2 },
+  { 149, 2 },
+  { 149, 2 },
+  { 149, 3 },
+  { 149, 5 },
+  { 154, 6 },
+  { 156, 1 },
+  { 158, 0 },
+  { 158, 3 },
+  { 157, 1 },
+  { 157, 0 },
+  { 155, 5 },
+  { 155, 2 },
+  { 162, 0 },
+  { 162, 2 },
+  { 164, 2 },
+  { 166, 0 },
+  { 166, 4 },
+  { 166, 6 },
+  { 167, 2 },
+  { 171, 2 },
+  { 171, 2 },
+  { 171, 4 },
+  { 171, 3 },
+  { 171, 3 },
+  { 171, 2 },
+  { 171, 3 },
+  { 171, 5 },
+  { 171, 2 },
+  { 171, 4 },
+  { 171, 4 },
+  { 171, 1 },
+  { 171, 2 },
+  { 176, 0 },
+  { 176, 1 },
+  { 178, 0 },
+  { 178, 2 },
+  { 180, 2 },
+  { 180, 3 },
+  { 180, 3 },
+  { 180, 3 },
+  { 181, 2 },
+  { 181, 2 },
+  { 181, 1 },
+  { 181, 1 },
+  { 181, 2 },
+  { 179, 3 },
+  { 179, 2 },
+  { 182, 0 },
+  { 182, 2 },
+  { 182, 2 },
+  { 161, 0 },
+  { 184, 1 },
+  { 185, 2 },
+  { 185, 7 },
+  { 185, 5 },
+  { 185, 5 },
+  { 185, 10 },
+  { 188, 0 },
+  { 174, 0 },
+  { 174, 3 },
+  { 189, 0 },
+  { 189, 2 },
+  { 190, 1 },
+  { 190, 1 },
+  { 149, 4 },
+  { 192, 2 },
+  { 192, 0 },
+  { 149, 9 },
+  { 149, 4 },
+  { 149, 1 },
+  { 163, 2 },
+  { 194, 3 },
+  { 197, 1 },
+  { 197, 2 },
+  { 197, 1 },
+  { 195, 9 },
+  { 206, 4 },
+  { 206, 5 },
+  { 198, 1 },
+  { 198, 1 },
+  { 198, 0 },
+  { 209, 0 },
+  { 199, 3 },
+  { 199, 2 },
+  { 199, 4 },
+  { 210, 2 },
+  { 210, 0 },
+  { 200, 0 },
+  { 200, 2 },
+  { 212, 2 },
+  { 212, 0 },
+  { 211, 7 },
+  { 211, 9 },
+  { 211, 7 },
+  { 211, 7 },
+  { 159, 0 },
+  { 159, 2 },
+  { 193, 2 },
+  { 213, 1 },
+  { 213, 2 },
+  { 213, 3 },
+  { 213, 4 },
+  { 215, 2 },
+  { 215, 0 },
+  { 214, 0 },
+  { 214, 3 },
+  { 214, 2 },
+  { 216, 4 },
+  { 216, 0 },
+  { 204, 0 },
+  { 204, 3 },
+  { 186, 4 },
+  { 186, 2 },
+  { 175, 1 },
+  { 175, 1 },
+  { 175, 0 },
+  { 202, 0 },
+  { 202, 3 },
+  { 203, 0 },
+  { 203, 2 },
+  { 205, 0 },
+  { 205, 2 },
+  { 205, 4 },
+  { 205, 4 },
+  { 149, 6 },
+  { 201, 0 },
+  { 201, 2 },
+  { 149, 8 },
+  { 218, 5 },
+  { 218, 7 },
+  { 218, 3 },
+  { 218, 5 },
+  { 149, 6 },
+  { 149, 7 },
+  { 219, 2 },
+  { 219, 1 },
+  { 220, 0 },
+  { 220, 3 },
+  { 217, 3 },
+  { 217, 1 },
+  { 173, 3 },
+  { 172, 1 },
+  { 173, 1 },
+  { 173, 1 },
+  { 173, 3 },
+  { 173, 5 },
+  { 172, 1 },
+  { 172, 1 },
+  { 172, 1 },
+  { 173, 1 },
+  { 173, 3 },
+  { 173, 6 },
+  { 173, 5 },
+  { 173, 4 },
+  { 172, 1 },
+  { 173, 5 },
+  { 173, 3 },
+  { 173, 3 },
+  { 173, 3 },
+  { 173, 3 },
+  { 173, 3 },
+  { 173, 3 },
+  { 173, 3 },
+  { 173, 3 },
+  { 221, 1 },
+  { 221, 2 },
+  { 173, 3 },
+  { 173, 5 },
+  { 173, 2 },
+  { 173, 3 },
+  { 173, 3 },
+  { 173, 4 },
+  { 173, 2 },
+  { 173, 2 },
+  { 173, 2 },
+  { 173, 2 },
+  { 222, 1 },
+  { 222, 2 },
+  { 173, 5 },
+  { 223, 1 },
+  { 223, 2 },
+  { 173, 5 },
+  { 173, 3 },
+  { 173, 5 },
+  { 173, 5 },
+  { 173, 4 },
+  { 173, 5 },
+  { 226, 5 },
+  { 226, 4 },
+  { 227, 2 },
+  { 227, 0 },
+  { 225, 1 },
+  { 225, 0 },
+  { 208, 0 },
+  { 207, 3 },
+  { 207, 1 },
+  { 224, 0 },
+  { 224, 3 },
+  { 149, 12 },
+  { 228, 1 },
+  { 228, 0 },
+  { 177, 0 },
+  { 177, 3 },
+  { 187, 5 },
+  { 187, 3 },
+  { 229, 0 },
+  { 229, 2 },
+  { 149, 4 },
+  { 149, 1 },
+  { 149, 2 },
+  { 149, 3 },
+  { 149, 5 },
+  { 149, 6 },
+  { 149, 5 },
+  { 149, 6 },
+  { 169, 2 },
+  { 170, 2 },
+  { 149, 5 },
+  { 231, 11 },
+  { 233, 1 },
+  { 233, 1 },
+  { 233, 2 },
+  { 233, 0 },
+  { 234, 1 },
+  { 234, 1 },
+  { 234, 3 },
+  { 236, 0 },
+  { 236, 2 },
+  { 232, 3 },
+  { 232, 2 },
+  { 238, 3 },
+  { 239, 3 },
+  { 239, 2 },
+  { 237, 7 },
+  { 237, 5 },
+  { 237, 5 },
+  { 237, 1 },
+  { 173, 4 },
+  { 173, 6 },
+  { 191, 1 },
+  { 191, 1 },
+  { 191, 1 },
+  { 149, 4 },
+  { 149, 6 },
+  { 149, 3 },
+  { 241, 0 },
+  { 241, 2 },
+  { 149, 1 },
+  { 149, 3 },
+  { 149, 1 },
+  { 149, 3 },
+  { 149, 6 },
+  { 149, 7 },
+  { 242, 1 },
+  { 149, 1 },
+  { 149, 4 },
+  { 244, 8 },
+  { 246, 0 },
+  { 247, 1 },
+  { 247, 3 },
+  { 248, 1 },
+  { 196, 0 },
+  { 196, 2 },
+  { 196, 3 },
+  { 250, 6 },
+  { 250, 8 },
+  { 144, 1 },
+  { 145, 2 },
+  { 145, 1 },
+  { 146, 1 },
+  { 146, 3 },
+  { 147, 0 },
+  { 151, 0 },
+  { 151, 1 },
+  { 151, 2 },
+  { 153, 1 },
+  { 153, 0 },
+  { 149, 2 },
+  { 160, 4 },
+  { 160, 2 },
+  { 152, 1 },
+  { 152, 1 },
+  { 152, 1 },
+  { 166, 1 },
+  { 167, 1 },
+  { 168, 1 },
+  { 168, 1 },
+  { 165, 2 },
+  { 165, 0 },
+  { 171, 2 },
+  { 161, 2 },
+  { 183, 3 },
+  { 183, 1 },
+  { 184, 0 },
+  { 188, 1 },
+  { 190, 1 },
+  { 194, 1 },
+  { 195, 1 },
+  { 209, 2 },
+  { 210, 1 },
+  { 173, 1 },
+  { 208, 1 },
+  { 230, 1 },
+  { 230, 1 },
+  { 230, 1 },
+  { 230, 1 },
+  { 230, 1 },
+  { 169, 1 },
+  { 235, 0 },
+  { 235, 3 },
+  { 238, 1 },
+  { 239, 0 },
+  { 240, 1 },
+  { 240, 0 },
+  { 243, 0 },
+  { 243, 1 },
+  { 245, 1 },
+  { 245, 3 },
+  { 246, 2 },
+  { 249, 0 },
+  { 249, 4 },
+  { 249, 2 },
+};
+
+static void yy_accept(yyParser*);  /* Forward Declaration */
+
+/*
+** Perform a reduce action and the shift that must immediately
+** follow the reduce.
+*/
+static void yy_reduce(
+  yyParser *yypParser,         /* The parser */
+  unsigned int yyruleno        /* Number of the rule by which to reduce */
+){
+  int yygoto;                     /* The next state */
+  int yyact;                      /* The next action */
+  yyStackEntry *yymsp;            /* The top of the parser's stack */
+  int yysize;                     /* Amount to pop the stack */
+  sqlite3ParserARG_FETCH;
+  yymsp = yypParser->yytos;
+#ifndef NDEBUG
+  if( yyTraceFILE && yyruleno<(int)(sizeof(yyRuleName)/sizeof(yyRuleName[0])) ){
+    yysize = yyRuleInfo[yyruleno].nrhs;
+    fprintf(yyTraceFILE, "%sReduce [%s], go to state %d.\n", yyTracePrompt,
+      yyRuleName[yyruleno], yymsp[-yysize].stateno);
+  }
+#endif /* NDEBUG */
+
+  /* Check that the stack is large enough to grow by a single entry
+  ** if the RHS of the rule is empty.  This ensures that there is room
+  ** enough on the stack to push the LHS value */
+  if( yyRuleInfo[yyruleno].nrhs==0 ){
+#ifdef YYTRACKMAXSTACKDEPTH
+    if( (int)(yypParser->yytos - yypParser->yystack)>yypParser->yyhwm ){
+      yypParser->yyhwm++;
+      assert( yypParser->yyhwm == (int)(yypParser->yytos - yypParser->yystack));
+    }
+#endif
+#if YYSTACKDEPTH>0 
+    if( yypParser->yytos>=&yypParser->yystack[YYSTACKDEPTH-1] ){
+      yyStackOverflow(yypParser);
+      return;
+    }
+#else
+    if( yypParser->yytos>=&yypParser->yystack[yypParser->yystksz-1] ){
+      if( yyGrowStack(yypParser) ){
+        yyStackOverflow(yypParser);
+        return;
+      }
+      yymsp = yypParser->yytos;
+    }
+#endif
+  }
+
+  switch( yyruleno ){
+  /* Beginning here are the reduction cases.  A typical example
+  ** follows:
+  **   case 0:
+  **  #line <lineno> <grammarfile>
+  **     { ... }           // User supplied code
+  **  #line <lineno> <thisfile>
+  **     break;
+  */
+/********** Begin reduce actions **********************************************/
+        YYMINORTYPE yylhsminor;
+      case 0: /* explain ::= EXPLAIN */
+{ pParse->explain = 1; }
+        break;
+      case 1: /* explain ::= EXPLAIN QUERY PLAN */
+{ pParse->explain = 2; }
+        break;
+      case 2: /* cmdx ::= cmd */
+{ sqlite3FinishCoding(pParse); }
+        break;
+      case 3: /* cmd ::= BEGIN transtype trans_opt */
+{sqlite3BeginTransaction(pParse, yymsp[-1].minor.yy194);}
+        break;
+      case 4: /* transtype ::= */
+{yymsp[1].minor.yy194 = TK_DEFERRED;}
+        break;
+      case 5: /* transtype ::= DEFERRED */
+      case 6: /* transtype ::= IMMEDIATE */ yytestcase(yyruleno==6);
+      case 7: /* transtype ::= EXCLUSIVE */ yytestcase(yyruleno==7);
+{yymsp[0].minor.yy194 = yymsp[0].major; /*A-overwrites-X*/}
+        break;
+      case 8: /* cmd ::= COMMIT trans_opt */
+      case 9: /* cmd ::= END trans_opt */ yytestcase(yyruleno==9);
+{sqlite3CommitTransaction(pParse);}
+        break;
+      case 10: /* cmd ::= ROLLBACK trans_opt */
+{sqlite3RollbackTransaction(pParse);}
+        break;
+      case 11: /* cmd ::= SAVEPOINT nm */
+{
+  sqlite3Savepoint(pParse, SAVEPOINT_BEGIN, &yymsp[0].minor.yy0);
+}
+        break;
+      case 12: /* cmd ::= RELEASE savepoint_opt nm */
+{
+  sqlite3Savepoint(pParse, SAVEPOINT_RELEASE, &yymsp[0].minor.yy0);
+}
+        break;
+      case 13: /* cmd ::= ROLLBACK trans_opt TO savepoint_opt nm */
+{
+  sqlite3Savepoint(pParse, SAVEPOINT_ROLLBACK, &yymsp[0].minor.yy0);
+}
+        break;
+      case 14: /* create_table ::= createkw temp TABLE ifnotexists nm dbnm */
+{
+   sqlite3StartTable(pParse,&yymsp[-1].minor.yy0,&yymsp[0].minor.yy0,yymsp[-4].minor.yy194,0,0,yymsp[-2].minor.yy194);
+}
+        break;
+      case 15: /* createkw ::= CREATE */
+{disableLookaside(pParse);}
+        break;
+      case 16: /* ifnotexists ::= */
+      case 19: /* temp ::= */ yytestcase(yyruleno==19);
+      case 22: /* table_options ::= */ yytestcase(yyruleno==22);
+      case 42: /* autoinc ::= */ yytestcase(yyruleno==42);
+      case 57: /* init_deferred_pred_opt ::= */ yytestcase(yyruleno==57);
+      case 67: /* defer_subclause_opt ::= */ yytestcase(yyruleno==67);
+      case 76: /* ifexists ::= */ yytestcase(yyruleno==76);
+      case 90: /* distinct ::= */ yytestcase(yyruleno==90);
+      case 215: /* collate ::= */ yytestcase(yyruleno==215);
+{yymsp[1].minor.yy194 = 0;}
+        break;
+      case 17: /* ifnotexists ::= IF NOT EXISTS */
+{yymsp[-2].minor.yy194 = 1;}
+        break;
+      case 18: /* temp ::= TEMP */
+      case 43: /* autoinc ::= AUTOINCR */ yytestcase(yyruleno==43);
+{yymsp[0].minor.yy194 = 1;}
+        break;
+      case 20: /* create_table_args ::= LP columnlist conslist_opt RP table_options */
+{
+  sqlite3EndTable(pParse,&yymsp[-2].minor.yy0,&yymsp[-1].minor.yy0,yymsp[0].minor.yy194,0);
+}
+        break;
+      case 21: /* create_table_args ::= AS select */
+{
+  sqlite3EndTable(pParse,0,0,0,yymsp[0].minor.yy243);
+  sqlite3SelectDelete(pParse->db, yymsp[0].minor.yy243);
+}
+        break;
+      case 23: /* table_options ::= WITHOUT nm */
+{
+  if( yymsp[0].minor.yy0.n==5 && sqlite3_strnicmp(yymsp[0].minor.yy0.z,"rowid",5)==0 ){
+    yymsp[-1].minor.yy194 = TF_WithoutRowid | TF_NoVisibleRowid;
+  }else{
+    yymsp[-1].minor.yy194 = 0;
+    sqlite3ErrorMsg(pParse, "unknown table option: %.*s", yymsp[0].minor.yy0.n, yymsp[0].minor.yy0.z);
+  }
+}
+        break;
+      case 24: /* columnname ::= nm typetoken */
+{sqlite3AddColumn(pParse,&yymsp[-1].minor.yy0,&yymsp[0].minor.yy0);}
+        break;
+      case 25: /* typetoken ::= */
+      case 60: /* conslist_opt ::= */ yytestcase(yyruleno==60);
+      case 96: /* as ::= */ yytestcase(yyruleno==96);
+{yymsp[1].minor.yy0.n = 0; yymsp[1].minor.yy0.z = 0;}
+        break;
+      case 26: /* typetoken ::= typename LP signed RP */
+{
+  yymsp[-3].minor.yy0.n = (int)(&yymsp[0].minor.yy0.z[yymsp[0].minor.yy0.n] - yymsp[-3].minor.yy0.z);
+}
+        break;
+      case 27: /* typetoken ::= typename LP signed COMMA signed RP */
+{
+  yymsp[-5].minor.yy0.n = (int)(&yymsp[0].minor.yy0.z[yymsp[0].minor.yy0.n] - yymsp[-5].minor.yy0.z);
+}
+        break;
+      case 28: /* typename ::= typename ID|STRING */
+{yymsp[-1].minor.yy0.n=yymsp[0].minor.yy0.n+(int)(yymsp[0].minor.yy0.z-yymsp[-1].minor.yy0.z);}
+        break;
+      case 29: /* ccons ::= CONSTRAINT nm */
+      case 62: /* tcons ::= CONSTRAINT nm */ yytestcase(yyruleno==62);
+{pParse->constraintName = yymsp[0].minor.yy0;}
+        break;
+      case 30: /* ccons ::= DEFAULT term */
+      case 32: /* ccons ::= DEFAULT PLUS term */ yytestcase(yyruleno==32);
+{sqlite3AddDefaultValue(pParse,&yymsp[0].minor.yy190);}
+        break;
+      case 31: /* ccons ::= DEFAULT LP expr RP */
+{sqlite3AddDefaultValue(pParse,&yymsp[-1].minor.yy190);}
+        break;
+      case 33: /* ccons ::= DEFAULT MINUS term */
+{
+  ExprSpan v;
+  v.pExpr = sqlite3PExpr(pParse, TK_UMINUS, yymsp[0].minor.yy190.pExpr, 0, 0);
+  v.zStart = yymsp[-1].minor.yy0.z;
+  v.zEnd = yymsp[0].minor.yy190.zEnd;
+  sqlite3AddDefaultValue(pParse,&v);
+}
+        break;
+      case 34: /* ccons ::= DEFAULT ID|INDEXED */
+{
+  ExprSpan v;
+  spanExpr(&v, pParse, TK_STRING, yymsp[0].minor.yy0);
+  sqlite3AddDefaultValue(pParse,&v);
+}
+        break;
+      case 35: /* ccons ::= NOT NULL onconf */
+{sqlite3AddNotNull(pParse, yymsp[0].minor.yy194);}
+        break;
+      case 36: /* ccons ::= PRIMARY KEY sortorder onconf autoinc */
+{sqlite3AddPrimaryKey(pParse,0,yymsp[-1].minor.yy194,yymsp[0].minor.yy194,yymsp[-2].minor.yy194);}
+        break;
+      case 37: /* ccons ::= UNIQUE onconf */
+{sqlite3CreateIndex(pParse,0,0,0,0,yymsp[0].minor.yy194,0,0,0,0,
+                                   SQLITE_IDXTYPE_UNIQUE);}
+        break;
+      case 38: /* ccons ::= CHECK LP expr RP */
+{sqlite3AddCheckConstraint(pParse,yymsp[-1].minor.yy190.pExpr);}
+        break;
+      case 39: /* ccons ::= REFERENCES nm eidlist_opt refargs */
+{sqlite3CreateForeignKey(pParse,0,&yymsp[-2].minor.yy0,yymsp[-1].minor.yy148,yymsp[0].minor.yy194);}
+        break;
+      case 40: /* ccons ::= defer_subclause */
+{sqlite3DeferForeignKey(pParse,yymsp[0].minor.yy194);}
+        break;
+      case 41: /* ccons ::= COLLATE ID|STRING */
+{sqlite3AddCollateType(pParse, &yymsp[0].minor.yy0);}
+        break;
+      case 44: /* refargs ::= */
+{ yymsp[1].minor.yy194 = OE_None*0x0101; /* EV: R-19803-45884 */}
+        break;
+      case 45: /* refargs ::= refargs refarg */
+{ yymsp[-1].minor.yy194 = (yymsp[-1].minor.yy194 & ~yymsp[0].minor.yy497.mask) | yymsp[0].minor.yy497.value; }
+        break;
+      case 46: /* refarg ::= MATCH nm */
+{ yymsp[-1].minor.yy497.value = 0;     yymsp[-1].minor.yy497.mask = 0x000000; }
+        break;
+      case 47: /* refarg ::= ON INSERT refact */
+{ yymsp[-2].minor.yy497.value = 0;     yymsp[-2].minor.yy497.mask = 0x000000; }
+        break;
+      case 48: /* refarg ::= ON DELETE refact */
+{ yymsp[-2].minor.yy497.value = yymsp[0].minor.yy194;     yymsp[-2].minor.yy497.mask = 0x0000ff; }
+        break;
+      case 49: /* refarg ::= ON UPDATE refact */
+{ yymsp[-2].minor.yy497.value = yymsp[0].minor.yy194<<8;  yymsp[-2].minor.yy497.mask = 0x00ff00; }
+        break;
+      case 50: /* refact ::= SET NULL */
+{ yymsp[-1].minor.yy194 = OE_SetNull;  /* EV: R-33326-45252 */}
+        break;
+      case 51: /* refact ::= SET DEFAULT */
+{ yymsp[-1].minor.yy194 = OE_SetDflt;  /* EV: R-33326-45252 */}
+        break;
+      case 52: /* refact ::= CASCADE */
+{ yymsp[0].minor.yy194 = OE_Cascade;  /* EV: R-33326-45252 */}
+        break;
+      case 53: /* refact ::= RESTRICT */
+{ yymsp[0].minor.yy194 = OE_Restrict; /* EV: R-33326-45252 */}
+        break;
+      case 54: /* refact ::= NO ACTION */
+{ yymsp[-1].minor.yy194 = OE_None;     /* EV: R-33326-45252 */}
+        break;
+      case 55: /* defer_subclause ::= NOT DEFERRABLE init_deferred_pred_opt */
+{yymsp[-2].minor.yy194 = 0;}
+        break;
+      case 56: /* defer_subclause ::= DEFERRABLE init_deferred_pred_opt */
+      case 71: /* orconf ::= OR resolvetype */ yytestcase(yyruleno==71);
+      case 144: /* insert_cmd ::= INSERT orconf */ yytestcase(yyruleno==144);
+{yymsp[-1].minor.yy194 = yymsp[0].minor.yy194;}
+        break;
+      case 58: /* init_deferred_pred_opt ::= INITIALLY DEFERRED */
+      case 75: /* ifexists ::= IF EXISTS */ yytestcase(yyruleno==75);
+      case 187: /* between_op ::= NOT BETWEEN */ yytestcase(yyruleno==187);
+      case 190: /* in_op ::= NOT IN */ yytestcase(yyruleno==190);
+      case 216: /* collate ::= COLLATE ID|STRING */ yytestcase(yyruleno==216);
+{yymsp[-1].minor.yy194 = 1;}
+        break;
+      case 59: /* init_deferred_pred_opt ::= INITIALLY IMMEDIATE */
+{yymsp[-1].minor.yy194 = 0;}
+        break;
+      case 61: /* tconscomma ::= COMMA */
+{pParse->constraintName.n = 0;}
+        break;
+      case 63: /* tcons ::= PRIMARY KEY LP sortlist autoinc RP onconf */
+{sqlite3AddPrimaryKey(pParse,yymsp[-3].minor.yy148,yymsp[0].minor.yy194,yymsp[-2].minor.yy194,0);}
+        break;
+      case 64: /* tcons ::= UNIQUE LP sortlist RP onconf */
+{sqlite3CreateIndex(pParse,0,0,0,yymsp[-2].minor.yy148,yymsp[0].minor.yy194,0,0,0,0,
+                                       SQLITE_IDXTYPE_UNIQUE);}
+        break;
+      case 65: /* tcons ::= CHECK LP expr RP onconf */
+{sqlite3AddCheckConstraint(pParse,yymsp[-2].minor.yy190.pExpr);}
+        break;
+      case 66: /* tcons ::= FOREIGN KEY LP eidlist RP REFERENCES nm eidlist_opt refargs defer_subclause_opt */
+{
+    sqlite3CreateForeignKey(pParse, yymsp[-6].minor.yy148, &yymsp[-3].minor.yy0, yymsp[-2].minor.yy148, yymsp[-1].minor.yy194);
+    sqlite3DeferForeignKey(pParse, yymsp[0].minor.yy194);
+}
+        break;
+      case 68: /* onconf ::= */
+      case 70: /* orconf ::= */ yytestcase(yyruleno==70);
+{yymsp[1].minor.yy194 = OE_Default;}
+        break;
+      case 69: /* onconf ::= ON CONFLICT resolvetype */
+{yymsp[-2].minor.yy194 = yymsp[0].minor.yy194;}
+        break;
+      case 72: /* resolvetype ::= IGNORE */
+{yymsp[0].minor.yy194 = OE_Ignore;}
+        break;
+      case 73: /* resolvetype ::= REPLACE */
+      case 145: /* insert_cmd ::= REPLACE */ yytestcase(yyruleno==145);
+{yymsp[0].minor.yy194 = OE_Replace;}
+        break;
+      case 74: /* cmd ::= DROP TABLE ifexists fullname */
+{
+  sqlite3DropTable(pParse, yymsp[0].minor.yy185, 0, yymsp[-1].minor.yy194);
+}
+        break;
+      case 77: /* cmd ::= createkw temp VIEW ifnotexists nm dbnm eidlist_opt AS select */
+{
+  sqlite3CreateView(pParse, &yymsp[-8].minor.yy0, &yymsp[-4].minor.yy0, &yymsp[-3].minor.yy0, yymsp[-2].minor.yy148, yymsp[0].minor.yy243, yymsp[-7].minor.yy194, yymsp[-5].minor.yy194);
+}
+        break;
+      case 78: /* cmd ::= DROP VIEW ifexists fullname */
+{
+  sqlite3DropTable(pParse, yymsp[0].minor.yy185, 1, yymsp[-1].minor.yy194);
+}
+        break;
+      case 79: /* cmd ::= select */
+{
+  SelectDest dest = {SRT_Output, 0, 0, 0, 0, 0};
+  sqlite3Select(pParse, yymsp[0].minor.yy243, &dest);
+  sqlite3SelectDelete(pParse->db, yymsp[0].minor.yy243);
+}
+        break;
+      case 80: /* select ::= with selectnowith */
+{
+  Select *p = yymsp[0].minor.yy243;
+  if( p ){
+    p->pWith = yymsp[-1].minor.yy285;
+    parserDoubleLinkSelect(pParse, p);
+  }else{
+    sqlite3WithDelete(pParse->db, yymsp[-1].minor.yy285);
+  }
+  yymsp[-1].minor.yy243 = p; /*A-overwrites-W*/
+}
+        break;
+      case 81: /* selectnowith ::= selectnowith multiselect_op oneselect */
+{
+  Select *pRhs = yymsp[0].minor.yy243;
+  Select *pLhs = yymsp[-2].minor.yy243;
+  if( pRhs && pRhs->pPrior ){
+    SrcList *pFrom;
+    Token x;
+    x.n = 0;
+    parserDoubleLinkSelect(pParse, pRhs);
+    pFrom = sqlite3SrcListAppendFromTerm(pParse,0,0,0,&x,pRhs,0,0);
+    pRhs = sqlite3SelectNew(pParse,0,pFrom,0,0,0,0,0,0,0);
+  }
+  if( pRhs ){
+    pRhs->op = (u8)yymsp[-1].minor.yy194;
+    pRhs->pPrior = pLhs;
+    if( ALWAYS(pLhs) ) pLhs->selFlags &= ~SF_MultiValue;
+    pRhs->selFlags &= ~SF_MultiValue;
+    if( yymsp[-1].minor.yy194!=TK_ALL ) pParse->hasCompound = 1;
+  }else{
+    sqlite3SelectDelete(pParse->db, pLhs);
+  }
+  yymsp[-2].minor.yy243 = pRhs;
+}
+        break;
+      case 82: /* multiselect_op ::= UNION */
+      case 84: /* multiselect_op ::= EXCEPT|INTERSECT */ yytestcase(yyruleno==84);
+{yymsp[0].minor.yy194 = yymsp[0].major; /*A-overwrites-OP*/}
+        break;
+      case 83: /* multiselect_op ::= UNION ALL */
+{yymsp[-1].minor.yy194 = TK_ALL;}
+        break;
+      case 85: /* oneselect ::= SELECT distinct selcollist from where_opt groupby_opt having_opt orderby_opt limit_opt */
+{
+#if SELECTTRACE_ENABLED
+  Token s = yymsp[-8].minor.yy0; /*A-overwrites-S*/
+#endif
+  yymsp[-8].minor.yy243 = sqlite3SelectNew(pParse,yymsp[-6].minor.yy148,yymsp[-5].minor.yy185,yymsp[-4].minor.yy72,yymsp[-3].minor.yy148,yymsp[-2].minor.yy72,yymsp[-1].minor.yy148,yymsp[-7].minor.yy194,yymsp[0].minor.yy354.pLimit,yymsp[0].minor.yy354.pOffset);
+#if SELECTTRACE_ENABLED
+  /* Populate the Select.zSelName[] string that is used to help with
+  ** query planner debugging, to differentiate between multiple Select
+  ** objects in a complex query.
+  **
+  ** If the SELECT keyword is immediately followed by a C-style comment
+  ** then extract the first few alphanumeric characters from within that
+  ** comment to be the zSelName value.  Otherwise, the label is #N where
+  ** is an integer that is incremented with each SELECT statement seen.
+  */
+  if( yymsp[-8].minor.yy243!=0 ){
+    const char *z = s.z+6;
+    int i;
+    sqlite3_snprintf(sizeof(yymsp[-8].minor.yy243->zSelName), yymsp[-8].minor.yy243->zSelName, "#%d",
+                     ++pParse->nSelect);
+    while( z[0]==' ' ) z++;
+    if( z[0]=='/' && z[1]=='*' ){
+      z += 2;
+      while( z[0]==' ' ) z++;
+      for(i=0; sqlite3Isalnum(z[i]); i++){}
+      sqlite3_snprintf(sizeof(yymsp[-8].minor.yy243->zSelName), yymsp[-8].minor.yy243->zSelName, "%.*s", i, z);
+    }
+  }
+#endif /* SELECTRACE_ENABLED */
+}
+        break;
+      case 86: /* values ::= VALUES LP nexprlist RP */
+{
+  yymsp[-3].minor.yy243 = sqlite3SelectNew(pParse,yymsp[-1].minor.yy148,0,0,0,0,0,SF_Values,0,0);
+}
+        break;
+      case 87: /* values ::= values COMMA LP exprlist RP */
+{
+  Select *pRight, *pLeft = yymsp[-4].minor.yy243;
+  pRight = sqlite3SelectNew(pParse,yymsp[-1].minor.yy148,0,0,0,0,0,SF_Values|SF_MultiValue,0,0);
+  if( ALWAYS(pLeft) ) pLeft->selFlags &= ~SF_MultiValue;
+  if( pRight ){
+    pRight->op = TK_ALL;
+    pRight->pPrior = pLeft;
+    yymsp[-4].minor.yy243 = pRight;
+  }else{
+    yymsp[-4].minor.yy243 = pLeft;
+  }
+}
+        break;
+      case 88: /* distinct ::= DISTINCT */
+{yymsp[0].minor.yy194 = SF_Distinct;}
+        break;
+      case 89: /* distinct ::= ALL */
+{yymsp[0].minor.yy194 = SF_All;}
+        break;
+      case 91: /* sclp ::= */
+      case 119: /* orderby_opt ::= */ yytestcase(yyruleno==119);
+      case 126: /* groupby_opt ::= */ yytestcase(yyruleno==126);
+      case 203: /* exprlist ::= */ yytestcase(yyruleno==203);
+      case 206: /* paren_exprlist ::= */ yytestcase(yyruleno==206);
+      case 211: /* eidlist_opt ::= */ yytestcase(yyruleno==211);
+{yymsp[1].minor.yy148 = 0;}
+        break;
+      case 92: /* selcollist ::= sclp expr as */
+{
+   yymsp[-2].minor.yy148 = sqlite3ExprListAppend(pParse, yymsp[-2].minor.yy148, yymsp[-1].minor.yy190.pExpr);
+   if( yymsp[0].minor.yy0.n>0 ) sqlite3ExprListSetName(pParse, yymsp[-2].minor.yy148, &yymsp[0].minor.yy0, 1);
+   sqlite3ExprListSetSpan(pParse,yymsp[-2].minor.yy148,&yymsp[-1].minor.yy190);
+}
+        break;
+      case 93: /* selcollist ::= sclp STAR */
+{
+  Expr *p = sqlite3Expr(pParse->db, TK_ASTERISK, 0);
+  yymsp[-1].minor.yy148 = sqlite3ExprListAppend(pParse, yymsp[-1].minor.yy148, p);
+}
+        break;
+      case 94: /* selcollist ::= sclp nm DOT STAR */
+{
+  Expr *pRight = sqlite3PExpr(pParse, TK_ASTERISK, 0, 0, 0);
+  Expr *pLeft = sqlite3PExpr(pParse, TK_ID, 0, 0, &yymsp[-2].minor.yy0);
+  Expr *pDot = sqlite3PExpr(pParse, TK_DOT, pLeft, pRight, 0);
+  yymsp[-3].minor.yy148 = sqlite3ExprListAppend(pParse,yymsp[-3].minor.yy148, pDot);
+}
+        break;
+      case 95: /* as ::= AS nm */
+      case 106: /* dbnm ::= DOT nm */ yytestcase(yyruleno==106);
+      case 225: /* plus_num ::= PLUS INTEGER|FLOAT */ yytestcase(yyruleno==225);
+      case 226: /* minus_num ::= MINUS INTEGER|FLOAT */ yytestcase(yyruleno==226);
+{yymsp[-1].minor.yy0 = yymsp[0].minor.yy0;}
+        break;
+      case 97: /* from ::= */
+{yymsp[1].minor.yy185 = sqlite3DbMallocZero(pParse->db, sizeof(*yymsp[1].minor.yy185));}
+        break;
+      case 98: /* from ::= FROM seltablist */
+{
+  yymsp[-1].minor.yy185 = yymsp[0].minor.yy185;
+  sqlite3SrcListShiftJoinType(yymsp[-1].minor.yy185);
+}
+        break;
+      case 99: /* stl_prefix ::= seltablist joinop */
+{
+   if( ALWAYS(yymsp[-1].minor.yy185 && yymsp[-1].minor.yy185->nSrc>0) ) yymsp[-1].minor.yy185->a[yymsp[-1].minor.yy185->nSrc-1].fg.jointype = (u8)yymsp[0].minor.yy194;
+}
+        break;
+      case 100: /* stl_prefix ::= */
+{yymsp[1].minor.yy185 = 0;}
+        break;
+      case 101: /* seltablist ::= stl_prefix nm dbnm as indexed_opt on_opt using_opt */
+{
+  yymsp[-6].minor.yy185 = sqlite3SrcListAppendFromTerm(pParse,yymsp[-6].minor.yy185,&yymsp[-5].minor.yy0,&yymsp[-4].minor.yy0,&yymsp[-3].minor.yy0,0,yymsp[-1].minor.yy72,yymsp[0].minor.yy254);
+  sqlite3SrcListIndexedBy(pParse, yymsp[-6].minor.yy185, &yymsp[-2].minor.yy0);
+}
+        break;
+      case 102: /* seltablist ::= stl_prefix nm dbnm LP exprlist RP as on_opt using_opt */
+{
+  yymsp[-8].minor.yy185 = sqlite3SrcListAppendFromTerm(pParse,yymsp[-8].minor.yy185,&yymsp[-7].minor.yy0,&yymsp[-6].minor.yy0,&yymsp[-2].minor.yy0,0,yymsp[-1].minor.yy72,yymsp[0].minor.yy254);
+  sqlite3SrcListFuncArgs(pParse, yymsp[-8].minor.yy185, yymsp[-4].minor.yy148);
+}
+        break;
+      case 103: /* seltablist ::= stl_prefix LP select RP as on_opt using_opt */
+{
+    yymsp[-6].minor.yy185 = sqlite3SrcListAppendFromTerm(pParse,yymsp[-6].minor.yy185,0,0,&yymsp[-2].minor.yy0,yymsp[-4].minor.yy243,yymsp[-1].minor.yy72,yymsp[0].minor.yy254);
+  }
+        break;
+      case 104: /* seltablist ::= stl_prefix LP seltablist RP as on_opt using_opt */
+{
+    if( yymsp[-6].minor.yy185==0 && yymsp[-2].minor.yy0.n==0 && yymsp[-1].minor.yy72==0 && yymsp[0].minor.yy254==0 ){
+      yymsp[-6].minor.yy185 = yymsp[-4].minor.yy185;
+    }else if( yymsp[-4].minor.yy185->nSrc==1 ){
+      yymsp[-6].minor.yy185 = sqlite3SrcListAppendFromTerm(pParse,yymsp[-6].minor.yy185,0,0,&yymsp[-2].minor.yy0,0,yymsp[-1].minor.yy72,yymsp[0].minor.yy254);
+      if( yymsp[-6].minor.yy185 ){
+        struct SrcList_item *pNew = &yymsp[-6].minor.yy185->a[yymsp[-6].minor.yy185->nSrc-1];
+        struct SrcList_item *pOld = yymsp[-4].minor.yy185->a;
+        pNew->zName = pOld->zName;
+        pNew->zDatabase = pOld->zDatabase;
+        pNew->pSelect = pOld->pSelect;
+        pOld->zName = pOld->zDatabase = 0;
+        pOld->pSelect = 0;
+      }
+      sqlite3SrcListDelete(pParse->db, yymsp[-4].minor.yy185);
+    }else{
+      Select *pSubquery;
+      sqlite3SrcListShiftJoinType(yymsp[-4].minor.yy185);
+      pSubquery = sqlite3SelectNew(pParse,0,yymsp[-4].minor.yy185,0,0,0,0,SF_NestedFrom,0,0);
+      yymsp[-6].minor.yy185 = sqlite3SrcListAppendFromTerm(pParse,yymsp[-6].minor.yy185,0,0,&yymsp[-2].minor.yy0,pSubquery,yymsp[-1].minor.yy72,yymsp[0].minor.yy254);
+    }
+  }
+        break;
+      case 105: /* dbnm ::= */
+      case 114: /* indexed_opt ::= */ yytestcase(yyruleno==114);
+{yymsp[1].minor.yy0.z=0; yymsp[1].minor.yy0.n=0;}
+        break;
+      case 107: /* fullname ::= nm dbnm */
+{yymsp[-1].minor.yy185 = sqlite3SrcListAppend(pParse->db,0,&yymsp[-1].minor.yy0,&yymsp[0].minor.yy0); /*A-overwrites-X*/}
+        break;
+      case 108: /* joinop ::= COMMA|JOIN */
+{ yymsp[0].minor.yy194 = JT_INNER; }
+        break;
+      case 109: /* joinop ::= JOIN_KW JOIN */
+{yymsp[-1].minor.yy194 = sqlite3JoinType(pParse,&yymsp[-1].minor.yy0,0,0);  /*X-overwrites-A*/}
+        break;
+      case 110: /* joinop ::= JOIN_KW nm JOIN */
+{yymsp[-2].minor.yy194 = sqlite3JoinType(pParse,&yymsp[-2].minor.yy0,&yymsp[-1].minor.yy0,0); /*X-overwrites-A*/}
+        break;
+      case 111: /* joinop ::= JOIN_KW nm nm JOIN */
+{yymsp[-3].minor.yy194 = sqlite3JoinType(pParse,&yymsp[-3].minor.yy0,&yymsp[-2].minor.yy0,&yymsp[-1].minor.yy0);/*X-overwrites-A*/}
+        break;
+      case 112: /* on_opt ::= ON expr */
+      case 129: /* having_opt ::= HAVING expr */ yytestcase(yyruleno==129);
+      case 136: /* where_opt ::= WHERE expr */ yytestcase(yyruleno==136);
+      case 199: /* case_else ::= ELSE expr */ yytestcase(yyruleno==199);
+{yymsp[-1].minor.yy72 = yymsp[0].minor.yy190.pExpr;}
+        break;
+      case 113: /* on_opt ::= */
+      case 128: /* having_opt ::= */ yytestcase(yyruleno==128);
+      case 135: /* where_opt ::= */ yytestcase(yyruleno==135);
+      case 200: /* case_else ::= */ yytestcase(yyruleno==200);
+      case 202: /* case_operand ::= */ yytestcase(yyruleno==202);
+{yymsp[1].minor.yy72 = 0;}
+        break;
+      case 115: /* indexed_opt ::= INDEXED BY nm */
+{yymsp[-2].minor.yy0 = yymsp[0].minor.yy0;}
+        break;
+      case 116: /* indexed_opt ::= NOT INDEXED */
+{yymsp[-1].minor.yy0.z=0; yymsp[-1].minor.yy0.n=1;}
+        break;
+      case 117: /* using_opt ::= USING LP idlist RP */
+{yymsp[-3].minor.yy254 = yymsp[-1].minor.yy254;}
+        break;
+      case 118: /* using_opt ::= */
+      case 146: /* idlist_opt ::= */ yytestcase(yyruleno==146);
+{yymsp[1].minor.yy254 = 0;}
+        break;
+      case 120: /* orderby_opt ::= ORDER BY sortlist */
+      case 127: /* groupby_opt ::= GROUP BY nexprlist */ yytestcase(yyruleno==127);
+{yymsp[-2].minor.yy148 = yymsp[0].minor.yy148;}
+        break;
+      case 121: /* sortlist ::= sortlist COMMA expr sortorder */
+{
+  yymsp[-3].minor.yy148 = sqlite3ExprListAppend(pParse,yymsp[-3].minor.yy148,yymsp[-1].minor.yy190.pExpr);
+  sqlite3ExprListSetSortOrder(yymsp[-3].minor.yy148,yymsp[0].minor.yy194);
+}
+        break;
+      case 122: /* sortlist ::= expr sortorder */
+{
+  yymsp[-1].minor.yy148 = sqlite3ExprListAppend(pParse,0,yymsp[-1].minor.yy190.pExpr); /*A-overwrites-Y*/
+  sqlite3ExprListSetSortOrder(yymsp[-1].minor.yy148,yymsp[0].minor.yy194);
+}
+        break;
+      case 123: /* sortorder ::= ASC */
+{yymsp[0].minor.yy194 = SQLITE_SO_ASC;}
+        break;
+      case 124: /* sortorder ::= DESC */
+{yymsp[0].minor.yy194 = SQLITE_SO_DESC;}
+        break;
+      case 125: /* sortorder ::= */
+{yymsp[1].minor.yy194 = SQLITE_SO_UNDEFINED;}
+        break;
+      case 130: /* limit_opt ::= */
+{yymsp[1].minor.yy354.pLimit = 0; yymsp[1].minor.yy354.pOffset = 0;}
+        break;
+      case 131: /* limit_opt ::= LIMIT expr */
+{yymsp[-1].minor.yy354.pLimit = yymsp[0].minor.yy190.pExpr; yymsp[-1].minor.yy354.pOffset = 0;}
+        break;
+      case 132: /* limit_opt ::= LIMIT expr OFFSET expr */
+{yymsp[-3].minor.yy354.pLimit = yymsp[-2].minor.yy190.pExpr; yymsp[-3].minor.yy354.pOffset = yymsp[0].minor.yy190.pExpr;}
+        break;
+      case 133: /* limit_opt ::= LIMIT expr COMMA expr */
+{yymsp[-3].minor.yy354.pOffset = yymsp[-2].minor.yy190.pExpr; yymsp[-3].minor.yy354.pLimit = yymsp[0].minor.yy190.pExpr;}
+        break;
+      case 134: /* cmd ::= with DELETE FROM fullname indexed_opt where_opt */
+{
+  sqlite3WithPush(pParse, yymsp[-5].minor.yy285, 1);
+  sqlite3SrcListIndexedBy(pParse, yymsp[-2].minor.yy185, &yymsp[-1].minor.yy0);
+  sqlite3DeleteFrom(pParse,yymsp[-2].minor.yy185,yymsp[0].minor.yy72);
+}
+        break;
+      case 137: /* cmd ::= with UPDATE orconf fullname indexed_opt SET setlist where_opt */
+{
+  sqlite3WithPush(pParse, yymsp[-7].minor.yy285, 1);
+  sqlite3SrcListIndexedBy(pParse, yymsp[-4].minor.yy185, &yymsp[-3].minor.yy0);
+  sqlite3ExprListCheckLength(pParse,yymsp[-1].minor.yy148,"set list"); 
+  sqlite3Update(pParse,yymsp[-4].minor.yy185,yymsp[-1].minor.yy148,yymsp[0].minor.yy72,yymsp[-5].minor.yy194);
+}
+        break;
+      case 138: /* setlist ::= setlist COMMA nm EQ expr */
+{
+  yymsp[-4].minor.yy148 = sqlite3ExprListAppend(pParse, yymsp[-4].minor.yy148, yymsp[0].minor.yy190.pExpr);
+  sqlite3ExprListSetName(pParse, yymsp[-4].minor.yy148, &yymsp[-2].minor.yy0, 1);
+}
+        break;
+      case 139: /* setlist ::= setlist COMMA LP idlist RP EQ expr */
+{
+  yymsp[-6].minor.yy148 = sqlite3ExprListAppendVector(pParse, yymsp[-6].minor.yy148, yymsp[-3].minor.yy254, yymsp[0].minor.yy190.pExpr);
+}
+        break;
+      case 140: /* setlist ::= nm EQ expr */
+{
+  yylhsminor.yy148 = sqlite3ExprListAppend(pParse, 0, yymsp[0].minor.yy190.pExpr);
+  sqlite3ExprListSetName(pParse, yylhsminor.yy148, &yymsp[-2].minor.yy0, 1);
+}
+  yymsp[-2].minor.yy148 = yylhsminor.yy148;
+        break;
+      case 141: /* setlist ::= LP idlist RP EQ expr */
+{
+  yymsp[-4].minor.yy148 = sqlite3ExprListAppendVector(pParse, 0, yymsp[-3].minor.yy254, yymsp[0].minor.yy190.pExpr);
+}
+        break;
+      case 142: /* cmd ::= with insert_cmd INTO fullname idlist_opt select */
+{
+  sqlite3WithPush(pParse, yymsp[-5].minor.yy285, 1);
+  sqlite3Insert(pParse, yymsp[-2].minor.yy185, yymsp[0].minor.yy243, yymsp[-1].minor.yy254, yymsp[-4].minor.yy194);
+}
+        break;
+      case 143: /* cmd ::= with insert_cmd INTO fullname idlist_opt DEFAULT VALUES */
+{
+  sqlite3WithPush(pParse, yymsp[-6].minor.yy285, 1);
+  sqlite3Insert(pParse, yymsp[-3].minor.yy185, 0, yymsp[-2].minor.yy254, yymsp[-5].minor.yy194);
+}
+        break;
+      case 147: /* idlist_opt ::= LP idlist RP */
+{yymsp[-2].minor.yy254 = yymsp[-1].minor.yy254;}
+        break;
+      case 148: /* idlist ::= idlist COMMA nm */
+{yymsp[-2].minor.yy254 = sqlite3IdListAppend(pParse->db,yymsp[-2].minor.yy254,&yymsp[0].minor.yy0);}
+        break;
+      case 149: /* idlist ::= nm */
+{yymsp[0].minor.yy254 = sqlite3IdListAppend(pParse->db,0,&yymsp[0].minor.yy0); /*A-overwrites-Y*/}
+        break;
+      case 150: /* expr ::= LP expr RP */
+{spanSet(&yymsp[-2].minor.yy190,&yymsp[-2].minor.yy0,&yymsp[0].minor.yy0); /*A-overwrites-B*/  yymsp[-2].minor.yy190.pExpr = yymsp[-1].minor.yy190.pExpr;}
+        break;
+      case 151: /* term ::= NULL */
+      case 156: /* term ::= FLOAT|BLOB */ yytestcase(yyruleno==156);
+      case 157: /* term ::= STRING */ yytestcase(yyruleno==157);
+{spanExpr(&yymsp[0].minor.yy190,pParse,yymsp[0].major,yymsp[0].minor.yy0);/*A-overwrites-X*/}
+        break;
+      case 152: /* expr ::= ID|INDEXED */
+      case 153: /* expr ::= JOIN_KW */ yytestcase(yyruleno==153);
+{spanExpr(&yymsp[0].minor.yy190,pParse,TK_ID,yymsp[0].minor.yy0); /*A-overwrites-X*/}
+        break;
+      case 154: /* expr ::= nm DOT nm */
+{
+  Expr *temp1 = sqlite3ExprAlloc(pParse->db, TK_ID, &yymsp[-2].minor.yy0, 1);
+  Expr *temp2 = sqlite3ExprAlloc(pParse->db, TK_ID, &yymsp[0].minor.yy0, 1);
+  spanSet(&yymsp[-2].minor.yy190,&yymsp[-2].minor.yy0,&yymsp[0].minor.yy0); /*A-overwrites-X*/
+  yymsp[-2].minor.yy190.pExpr = sqlite3PExpr(pParse, TK_DOT, temp1, temp2, 0);
+}
+        break;
+      case 155: /* expr ::= nm DOT nm DOT nm */
+{
+  Expr *temp1 = sqlite3ExprAlloc(pParse->db, TK_ID, &yymsp[-4].minor.yy0, 1);
+  Expr *temp2 = sqlite3ExprAlloc(pParse->db, TK_ID, &yymsp[-2].minor.yy0, 1);
+  Expr *temp3 = sqlite3ExprAlloc(pParse->db, TK_ID, &yymsp[0].minor.yy0, 1);
+  Expr *temp4 = sqlite3PExpr(pParse, TK_DOT, temp2, temp3, 0);
+  spanSet(&yymsp[-4].minor.yy190,&yymsp[-4].minor.yy0,&yymsp[0].minor.yy0); /*A-overwrites-X*/
+  yymsp[-4].minor.yy190.pExpr = sqlite3PExpr(pParse, TK_DOT, temp1, temp4, 0);
+}
+        break;
+      case 158: /* term ::= INTEGER */
+{
+  yylhsminor.yy190.pExpr = sqlite3ExprAlloc(pParse->db, TK_INTEGER, &yymsp[0].minor.yy0, 1);
+  yylhsminor.yy190.zStart = yymsp[0].minor.yy0.z;
+  yylhsminor.yy190.zEnd = yymsp[0].minor.yy0.z + yymsp[0].minor.yy0.n;
+  if( yylhsminor.yy190.pExpr ) yylhsminor.yy190.pExpr->flags |= EP_Leaf;
+}
+  yymsp[0].minor.yy190 = yylhsminor.yy190;
+        break;
+      case 159: /* expr ::= VARIABLE */
+{
+  if( !(yymsp[0].minor.yy0.z[0]=='#' && sqlite3Isdigit(yymsp[0].minor.yy0.z[1])) ){
+    u32 n = yymsp[0].minor.yy0.n;
+    spanExpr(&yymsp[0].minor.yy190, pParse, TK_VARIABLE, yymsp[0].minor.yy0);
+    sqlite3ExprAssignVarNumber(pParse, yymsp[0].minor.yy190.pExpr, n);
+  }else{
+    /* When doing a nested parse, one can include terms in an expression
+    ** that look like this:   #1 #2 ...  These terms refer to registers
+    ** in the virtual machine.  #N is the N-th register. */
+    Token t = yymsp[0].minor.yy0; /*A-overwrites-X*/
+    assert( t.n>=2 );
+    spanSet(&yymsp[0].minor.yy190, &t, &t);
+    if( pParse->nested==0 ){
+      sqlite3ErrorMsg(pParse, "near \"%T\": syntax error", &t);
+      yymsp[0].minor.yy190.pExpr = 0;
+    }else{
+      yymsp[0].minor.yy190.pExpr = sqlite3PExpr(pParse, TK_REGISTER, 0, 0, 0);
+      if( yymsp[0].minor.yy190.pExpr ) sqlite3GetInt32(&t.z[1], &yymsp[0].minor.yy190.pExpr->iTable);
+    }
+  }
+}
+        break;
+      case 160: /* expr ::= expr COLLATE ID|STRING */
+{
+  yymsp[-2].minor.yy190.pExpr = sqlite3ExprAddCollateToken(pParse, yymsp[-2].minor.yy190.pExpr, &yymsp[0].minor.yy0, 1);
+  yymsp[-2].minor.yy190.zEnd = &yymsp[0].minor.yy0.z[yymsp[0].minor.yy0.n];
+}
+        break;
+      case 161: /* expr ::= CAST LP expr AS typetoken RP */
+{
+  spanSet(&yymsp[-5].minor.yy190,&yymsp[-5].minor.yy0,&yymsp[0].minor.yy0); /*A-overwrites-X*/
+  yymsp[-5].minor.yy190.pExpr = sqlite3PExpr(pParse, TK_CAST, yymsp[-3].minor.yy190.pExpr, 0, &yymsp[-1].minor.yy0);
+}
+        break;
+      case 162: /* expr ::= ID|INDEXED LP distinct exprlist RP */
+{
+  if( yymsp[-1].minor.yy148 && yymsp[-1].minor.yy148->nExpr>pParse->db->aLimit[SQLITE_LIMIT_FUNCTION_ARG] ){
+    sqlite3ErrorMsg(pParse, "too many arguments on function %T", &yymsp[-4].minor.yy0);
+  }
+  yylhsminor.yy190.pExpr = sqlite3ExprFunction(pParse, yymsp[-1].minor.yy148, &yymsp[-4].minor.yy0);
+  spanSet(&yylhsminor.yy190,&yymsp[-4].minor.yy0,&yymsp[0].minor.yy0);
+  if( yymsp[-2].minor.yy194==SF_Distinct && yylhsminor.yy190.pExpr ){
+    yylhsminor.yy190.pExpr->flags |= EP_Distinct;
+  }
+}
+  yymsp[-4].minor.yy190 = yylhsminor.yy190;
+        break;
+      case 163: /* expr ::= ID|INDEXED LP STAR RP */
+{
+  yylhsminor.yy190.pExpr = sqlite3ExprFunction(pParse, 0, &yymsp[-3].minor.yy0);
+  spanSet(&yylhsminor.yy190,&yymsp[-3].minor.yy0,&yymsp[0].minor.yy0);
+}
+  yymsp[-3].minor.yy190 = yylhsminor.yy190;
+        break;
+      case 164: /* term ::= CTIME_KW */
+{
+  yylhsminor.yy190.pExpr = sqlite3ExprFunction(pParse, 0, &yymsp[0].minor.yy0);
+  spanSet(&yylhsminor.yy190, &yymsp[0].minor.yy0, &yymsp[0].minor.yy0);
+}
+  yymsp[0].minor.yy190 = yylhsminor.yy190;
+        break;
+      case 165: /* expr ::= LP nexprlist COMMA expr RP */
+{
+  ExprList *pList = sqlite3ExprListAppend(pParse, yymsp[-3].minor.yy148, yymsp[-1].minor.yy190.pExpr);
+  yylhsminor.yy190.pExpr = sqlite3PExpr(pParse, TK_VECTOR, 0, 0, 0);
+  if( yylhsminor.yy190.pExpr ){
+    yylhsminor.yy190.pExpr->x.pList = pList;
+    spanSet(&yylhsminor.yy190, &yymsp[-4].minor.yy0, &yymsp[0].minor.yy0);
+  }else{
+    sqlite3ExprListDelete(pParse->db, pList);
+  }
+}
+  yymsp[-4].minor.yy190 = yylhsminor.yy190;
+        break;
+      case 166: /* expr ::= expr AND expr */
+      case 167: /* expr ::= expr OR expr */ yytestcase(yyruleno==167);
+      case 168: /* expr ::= expr LT|GT|GE|LE expr */ yytestcase(yyruleno==168);
+      case 169: /* expr ::= expr EQ|NE expr */ yytestcase(yyruleno==169);
+      case 170: /* expr ::= expr BITAND|BITOR|LSHIFT|RSHIFT expr */ yytestcase(yyruleno==170);
+      case 171: /* expr ::= expr PLUS|MINUS expr */ yytestcase(yyruleno==171);
+      case 172: /* expr ::= expr STAR|SLASH|REM expr */ yytestcase(yyruleno==172);
+      case 173: /* expr ::= expr CONCAT expr */ yytestcase(yyruleno==173);
+{spanBinaryExpr(pParse,yymsp[-1].major,&yymsp[-2].minor.yy190,&yymsp[0].minor.yy190);}
+        break;
+      case 174: /* likeop ::= LIKE_KW|MATCH */
+{yymsp[0].minor.yy0=yymsp[0].minor.yy0;/*A-overwrites-X*/}
+        break;
+      case 175: /* likeop ::= NOT LIKE_KW|MATCH */
+{yymsp[-1].minor.yy0=yymsp[0].minor.yy0; yymsp[-1].minor.yy0.n|=0x80000000; /*yymsp[-1].minor.yy0-overwrite-yymsp[0].minor.yy0*/}
+        break;
+      case 176: /* expr ::= expr likeop expr */
+{
+  ExprList *pList;
+  int bNot = yymsp[-1].minor.yy0.n & 0x80000000;
+  yymsp[-1].minor.yy0.n &= 0x7fffffff;
+  pList = sqlite3ExprListAppend(pParse,0, yymsp[0].minor.yy190.pExpr);
+  pList = sqlite3ExprListAppend(pParse,pList, yymsp[-2].minor.yy190.pExpr);
+  yymsp[-2].minor.yy190.pExpr = sqlite3ExprFunction(pParse, pList, &yymsp[-1].minor.yy0);
+  exprNot(pParse, bNot, &yymsp[-2].minor.yy190);
+  yymsp[-2].minor.yy190.zEnd = yymsp[0].minor.yy190.zEnd;
+  if( yymsp[-2].minor.yy190.pExpr ) yymsp[-2].minor.yy190.pExpr->flags |= EP_InfixFunc;
+}
+        break;
+      case 177: /* expr ::= expr likeop expr ESCAPE expr */
+{
+  ExprList *pList;
+  int bNot = yymsp[-3].minor.yy0.n & 0x80000000;
+  yymsp[-3].minor.yy0.n &= 0x7fffffff;
+  pList = sqlite3ExprListAppend(pParse,0, yymsp[-2].minor.yy190.pExpr);
+  pList = sqlite3ExprListAppend(pParse,pList, yymsp[-4].minor.yy190.pExpr);
+  pList = sqlite3ExprListAppend(pParse,pList, yymsp[0].minor.yy190.pExpr);
+  yymsp[-4].minor.yy190.pExpr = sqlite3ExprFunction(pParse, pList, &yymsp[-3].minor.yy0);
+  exprNot(pParse, bNot, &yymsp[-4].minor.yy190);
+  yymsp[-4].minor.yy190.zEnd = yymsp[0].minor.yy190.zEnd;
+  if( yymsp[-4].minor.yy190.pExpr ) yymsp[-4].minor.yy190.pExpr->flags |= EP_InfixFunc;
+}
+        break;
+      case 178: /* expr ::= expr ISNULL|NOTNULL */
+{spanUnaryPostfix(pParse,yymsp[0].major,&yymsp[-1].minor.yy190,&yymsp[0].minor.yy0);}
+        break;
+      case 179: /* expr ::= expr NOT NULL */
+{spanUnaryPostfix(pParse,TK_NOTNULL,&yymsp[-2].minor.yy190,&yymsp[0].minor.yy0);}
+        break;
+      case 180: /* expr ::= expr IS expr */
+{
+  spanBinaryExpr(pParse,TK_IS,&yymsp[-2].minor.yy190,&yymsp[0].minor.yy190);
+  binaryToUnaryIfNull(pParse, yymsp[0].minor.yy190.pExpr, yymsp[-2].minor.yy190.pExpr, TK_ISNULL);
+}
+        break;
+      case 181: /* expr ::= expr IS NOT expr */
+{
+  spanBinaryExpr(pParse,TK_ISNOT,&yymsp[-3].minor.yy190,&yymsp[0].minor.yy190);
+  binaryToUnaryIfNull(pParse, yymsp[0].minor.yy190.pExpr, yymsp[-3].minor.yy190.pExpr, TK_NOTNULL);
+}
+        break;
+      case 182: /* expr ::= NOT expr */
+      case 183: /* expr ::= BITNOT expr */ yytestcase(yyruleno==183);
+{spanUnaryPrefix(&yymsp[-1].minor.yy190,pParse,yymsp[-1].major,&yymsp[0].minor.yy190,&yymsp[-1].minor.yy0);/*A-overwrites-B*/}
+        break;
+      case 184: /* expr ::= MINUS expr */
+{spanUnaryPrefix(&yymsp[-1].minor.yy190,pParse,TK_UMINUS,&yymsp[0].minor.yy190,&yymsp[-1].minor.yy0);/*A-overwrites-B*/}
+        break;
+      case 185: /* expr ::= PLUS expr */
+{spanUnaryPrefix(&yymsp[-1].minor.yy190,pParse,TK_UPLUS,&yymsp[0].minor.yy190,&yymsp[-1].minor.yy0);/*A-overwrites-B*/}
+        break;
+      case 186: /* between_op ::= BETWEEN */
+      case 189: /* in_op ::= IN */ yytestcase(yyruleno==189);
+{yymsp[0].minor.yy194 = 0;}
+        break;
+      case 188: /* expr ::= expr between_op expr AND expr */
+{
+  ExprList *pList = sqlite3ExprListAppend(pParse,0, yymsp[-2].minor.yy190.pExpr);
+  pList = sqlite3ExprListAppend(pParse,pList, yymsp[0].minor.yy190.pExpr);
+  yymsp[-4].minor.yy190.pExpr = sqlite3PExpr(pParse, TK_BETWEEN, yymsp[-4].minor.yy190.pExpr, 0, 0);
+  if( yymsp[-4].minor.yy190.pExpr ){
+    yymsp[-4].minor.yy190.pExpr->x.pList = pList;
+  }else{
+    sqlite3ExprListDelete(pParse->db, pList);
+  } 
+  exprNot(pParse, yymsp[-3].minor.yy194, &yymsp[-4].minor.yy190);
+  yymsp[-4].minor.yy190.zEnd = yymsp[0].minor.yy190.zEnd;
+}
+        break;
+      case 191: /* expr ::= expr in_op LP exprlist RP */
+{
+    if( yymsp[-1].minor.yy148==0 ){
+      /* Expressions of the form
+      **
+      **      expr1 IN ()
+      **      expr1 NOT IN ()
+      **
+      ** simplify to constants 0 (false) and 1 (true), respectively,
+      ** regardless of the value of expr1.
+      */
+      sqlite3ExprDelete(pParse->db, yymsp[-4].minor.yy190.pExpr);
+      yymsp[-4].minor.yy190.pExpr = sqlite3PExpr(pParse, TK_INTEGER, 0, 0, &sqlite3IntTokens[yymsp[-3].minor.yy194]);
+    }else if( yymsp[-1].minor.yy148->nExpr==1 ){
+      /* Expressions of the form:
+      **
+      **      expr1 IN (?1)
+      **      expr1 NOT IN (?2)
+      **
+      ** with exactly one value on the RHS can be simplified to something
+      ** like this:
+      **
+      **      expr1 == ?1
+      **      expr1 <> ?2
+      **
+      ** But, the RHS of the == or <> is marked with the EP_Generic flag
+      ** so that it may not contribute to the computation of comparison
+      ** affinity or the collating sequence to use for comparison.  Otherwise,
+      ** the semantics would be subtly different from IN or NOT IN.
+      */
+      Expr *pRHS = yymsp[-1].minor.yy148->a[0].pExpr;
+      yymsp[-1].minor.yy148->a[0].pExpr = 0;
+      sqlite3ExprListDelete(pParse->db, yymsp[-1].minor.yy148);
+      /* pRHS cannot be NULL because a malloc error would have been detected
+      ** before now and control would have never reached this point */
+      if( ALWAYS(pRHS) ){
+        pRHS->flags &= ~EP_Collate;
+        pRHS->flags |= EP_Generic;
+      }
+      yymsp[-4].minor.yy190.pExpr = sqlite3PExpr(pParse, yymsp[-3].minor.yy194 ? TK_NE : TK_EQ, yymsp[-4].minor.yy190.pExpr, pRHS, 0);
+    }else{
+      yymsp[-4].minor.yy190.pExpr = sqlite3PExpr(pParse, TK_IN, yymsp[-4].minor.yy190.pExpr, 0, 0);
+      if( yymsp[-4].minor.yy190.pExpr ){
+        yymsp[-4].minor.yy190.pExpr->x.pList = yymsp[-1].minor.yy148;
+        sqlite3ExprSetHeightAndFlags(pParse, yymsp[-4].minor.yy190.pExpr);
+      }else{
+        sqlite3ExprListDelete(pParse->db, yymsp[-1].minor.yy148);
+      }
+      exprNot(pParse, yymsp[-3].minor.yy194, &yymsp[-4].minor.yy190);
+    }
+    yymsp[-4].minor.yy190.zEnd = &yymsp[0].minor.yy0.z[yymsp[0].minor.yy0.n];
+  }
+        break;
+      case 192: /* expr ::= LP select RP */
+{
+    spanSet(&yymsp[-2].minor.yy190,&yymsp[-2].minor.yy0,&yymsp[0].minor.yy0); /*A-overwrites-B*/
+    yymsp[-2].minor.yy190.pExpr = sqlite3PExpr(pParse, TK_SELECT, 0, 0, 0);
+    sqlite3PExprAddSelect(pParse, yymsp[-2].minor.yy190.pExpr, yymsp[-1].minor.yy243);
+  }
+        break;
+      case 193: /* expr ::= expr in_op LP select RP */
+{
+    yymsp[-4].minor.yy190.pExpr = sqlite3PExpr(pParse, TK_IN, yymsp[-4].minor.yy190.pExpr, 0, 0);
+    sqlite3PExprAddSelect(pParse, yymsp[-4].minor.yy190.pExpr, yymsp[-1].minor.yy243);
+    exprNot(pParse, yymsp[-3].minor.yy194, &yymsp[-4].minor.yy190);
+    yymsp[-4].minor.yy190.zEnd = &yymsp[0].minor.yy0.z[yymsp[0].minor.yy0.n];
+  }
+        break;
+      case 194: /* expr ::= expr in_op nm dbnm paren_exprlist */
+{
+    SrcList *pSrc = sqlite3SrcListAppend(pParse->db, 0,&yymsp[-2].minor.yy0,&yymsp[-1].minor.yy0);
+    Select *pSelect = sqlite3SelectNew(pParse, 0,pSrc,0,0,0,0,0,0,0);
+    if( yymsp[0].minor.yy148 )  sqlite3SrcListFuncArgs(pParse, pSelect ? pSrc : 0, yymsp[0].minor.yy148);
+    yymsp[-4].minor.yy190.pExpr = sqlite3PExpr(pParse, TK_IN, yymsp[-4].minor.yy190.pExpr, 0, 0);
+    sqlite3PExprAddSelect(pParse, yymsp[-4].minor.yy190.pExpr, pSelect);
+    exprNot(pParse, yymsp[-3].minor.yy194, &yymsp[-4].minor.yy190);
+    yymsp[-4].minor.yy190.zEnd = yymsp[-1].minor.yy0.z ? &yymsp[-1].minor.yy0.z[yymsp[-1].minor.yy0.n] : &yymsp[-2].minor.yy0.z[yymsp[-2].minor.yy0.n];
+  }
+        break;
+      case 195: /* expr ::= EXISTS LP select RP */
+{
+    Expr *p;
+    spanSet(&yymsp[-3].minor.yy190,&yymsp[-3].minor.yy0,&yymsp[0].minor.yy0); /*A-overwrites-B*/
+    p = yymsp[-3].minor.yy190.pExpr = sqlite3PExpr(pParse, TK_EXISTS, 0, 0, 0);
+    sqlite3PExprAddSelect(pParse, p, yymsp[-1].minor.yy243);
+  }
+        break;
+      case 196: /* expr ::= CASE case_operand case_exprlist case_else END */
+{
+  spanSet(&yymsp[-4].minor.yy190,&yymsp[-4].minor.yy0,&yymsp[0].minor.yy0);  /*A-overwrites-C*/
+  yymsp[-4].minor.yy190.pExpr = sqlite3PExpr(pParse, TK_CASE, yymsp[-3].minor.yy72, 0, 0);
+  if( yymsp[-4].minor.yy190.pExpr ){
+    yymsp[-4].minor.yy190.pExpr->x.pList = yymsp[-1].minor.yy72 ? sqlite3ExprListAppend(pParse,yymsp[-2].minor.yy148,yymsp[-1].minor.yy72) : yymsp[-2].minor.yy148;
+    sqlite3ExprSetHeightAndFlags(pParse, yymsp[-4].minor.yy190.pExpr);
+  }else{
+    sqlite3ExprListDelete(pParse->db, yymsp[-2].minor.yy148);
+    sqlite3ExprDelete(pParse->db, yymsp[-1].minor.yy72);
+  }
+}
+        break;
+      case 197: /* case_exprlist ::= case_exprlist WHEN expr THEN expr */
+{
+  yymsp[-4].minor.yy148 = sqlite3ExprListAppend(pParse,yymsp[-4].minor.yy148, yymsp[-2].minor.yy190.pExpr);
+  yymsp[-4].minor.yy148 = sqlite3ExprListAppend(pParse,yymsp[-4].minor.yy148, yymsp[0].minor.yy190.pExpr);
+}
+        break;
+      case 198: /* case_exprlist ::= WHEN expr THEN expr */
+{
+  yymsp[-3].minor.yy148 = sqlite3ExprListAppend(pParse,0, yymsp[-2].minor.yy190.pExpr);
+  yymsp[-3].minor.yy148 = sqlite3ExprListAppend(pParse,yymsp[-3].minor.yy148, yymsp[0].minor.yy190.pExpr);
+}
+        break;
+      case 201: /* case_operand ::= expr */
+{yymsp[0].minor.yy72 = yymsp[0].minor.yy190.pExpr; /*A-overwrites-X*/}
+        break;
+      case 204: /* nexprlist ::= nexprlist COMMA expr */
+{yymsp[-2].minor.yy148 = sqlite3ExprListAppend(pParse,yymsp[-2].minor.yy148,yymsp[0].minor.yy190.pExpr);}
+        break;
+      case 205: /* nexprlist ::= expr */
+{yymsp[0].minor.yy148 = sqlite3ExprListAppend(pParse,0,yymsp[0].minor.yy190.pExpr); /*A-overwrites-Y*/}
+        break;
+      case 207: /* paren_exprlist ::= LP exprlist RP */
+      case 212: /* eidlist_opt ::= LP eidlist RP */ yytestcase(yyruleno==212);
+{yymsp[-2].minor.yy148 = yymsp[-1].minor.yy148;}
+        break;
+      case 208: /* cmd ::= createkw uniqueflag INDEX ifnotexists nm dbnm ON nm LP sortlist RP where_opt */
+{
+  sqlite3CreateIndex(pParse, &yymsp[-7].minor.yy0, &yymsp[-6].minor.yy0, 
+                     sqlite3SrcListAppend(pParse->db,0,&yymsp[-4].minor.yy0,0), yymsp[-2].minor.yy148, yymsp[-10].minor.yy194,
+                      &yymsp[-11].minor.yy0, yymsp[0].minor.yy72, SQLITE_SO_ASC, yymsp[-8].minor.yy194, SQLITE_IDXTYPE_APPDEF);
+}
+        break;
+      case 209: /* uniqueflag ::= UNIQUE */
+      case 250: /* raisetype ::= ABORT */ yytestcase(yyruleno==250);
+{yymsp[0].minor.yy194 = OE_Abort;}
+        break;
+      case 210: /* uniqueflag ::= */
+{yymsp[1].minor.yy194 = OE_None;}
+        break;
+      case 213: /* eidlist ::= eidlist COMMA nm collate sortorder */
+{
+  yymsp[-4].minor.yy148 = parserAddExprIdListTerm(pParse, yymsp[-4].minor.yy148, &yymsp[-2].minor.yy0, yymsp[-1].minor.yy194, yymsp[0].minor.yy194);
+}
+        break;
+      case 214: /* eidlist ::= nm collate sortorder */
+{
+  yymsp[-2].minor.yy148 = parserAddExprIdListTerm(pParse, 0, &yymsp[-2].minor.yy0, yymsp[-1].minor.yy194, yymsp[0].minor.yy194); /*A-overwrites-Y*/
+}
+        break;
+      case 217: /* cmd ::= DROP INDEX ifexists fullname */
+{sqlite3DropIndex(pParse, yymsp[0].minor.yy185, yymsp[-1].minor.yy194);}
+        break;
+      case 218: /* cmd ::= VACUUM */
+{sqlite3Vacuum(pParse,0);}
+        break;
+      case 219: /* cmd ::= VACUUM nm */
+{sqlite3Vacuum(pParse,&yymsp[0].minor.yy0);}
+        break;
+      case 220: /* cmd ::= PRAGMA nm dbnm */
+{sqlite3Pragma(pParse,&yymsp[-1].minor.yy0,&yymsp[0].minor.yy0,0,0);}
+        break;
+      case 221: /* cmd ::= PRAGMA nm dbnm EQ nmnum */
+{sqlite3Pragma(pParse,&yymsp[-3].minor.yy0,&yymsp[-2].minor.yy0,&yymsp[0].minor.yy0,0);}
+        break;
+      case 222: /* cmd ::= PRAGMA nm dbnm LP nmnum RP */
+{sqlite3Pragma(pParse,&yymsp[-4].minor.yy0,&yymsp[-3].minor.yy0,&yymsp[-1].minor.yy0,0);}
+        break;
+      case 223: /* cmd ::= PRAGMA nm dbnm EQ minus_num */
+{sqlite3Pragma(pParse,&yymsp[-3].minor.yy0,&yymsp[-2].minor.yy0,&yymsp[0].minor.yy0,1);}
+        break;
+      case 224: /* cmd ::= PRAGMA nm dbnm LP minus_num RP */
+{sqlite3Pragma(pParse,&yymsp[-4].minor.yy0,&yymsp[-3].minor.yy0,&yymsp[-1].minor.yy0,1);}
+        break;
+      case 227: /* cmd ::= createkw trigger_decl BEGIN trigger_cmd_list END */
+{
+  Token all;
+  all.z = yymsp[-3].minor.yy0.z;
+  all.n = (int)(yymsp[0].minor.yy0.z - yymsp[-3].minor.yy0.z) + yymsp[0].minor.yy0.n;
+  sqlite3FinishTrigger(pParse, yymsp[-1].minor.yy145, &all);
+}
+        break;
+      case 228: /* trigger_decl ::= temp TRIGGER ifnotexists nm dbnm trigger_time trigger_event ON fullname foreach_clause when_clause */
+{
+  sqlite3BeginTrigger(pParse, &yymsp[-7].minor.yy0, &yymsp[-6].minor.yy0, yymsp[-5].minor.yy194, yymsp[-4].minor.yy332.a, yymsp[-4].minor.yy332.b, yymsp[-2].minor.yy185, yymsp[0].minor.yy72, yymsp[-10].minor.yy194, yymsp[-8].minor.yy194);
+  yymsp[-10].minor.yy0 = (yymsp[-6].minor.yy0.n==0?yymsp[-7].minor.yy0:yymsp[-6].minor.yy0); /*A-overwrites-T*/
+}
+        break;
+      case 229: /* trigger_time ::= BEFORE */
+{ yymsp[0].minor.yy194 = TK_BEFORE; }
+        break;
+      case 230: /* trigger_time ::= AFTER */
+{ yymsp[0].minor.yy194 = TK_AFTER;  }
+        break;
+      case 231: /* trigger_time ::= INSTEAD OF */
+{ yymsp[-1].minor.yy194 = TK_INSTEAD;}
+        break;
+      case 232: /* trigger_time ::= */
+{ yymsp[1].minor.yy194 = TK_BEFORE; }
+        break;
+      case 233: /* trigger_event ::= DELETE|INSERT */
+      case 234: /* trigger_event ::= UPDATE */ yytestcase(yyruleno==234);
+{yymsp[0].minor.yy332.a = yymsp[0].major; /*A-overwrites-X*/ yymsp[0].minor.yy332.b = 0;}
+        break;
+      case 235: /* trigger_event ::= UPDATE OF idlist */
+{yymsp[-2].minor.yy332.a = TK_UPDATE; yymsp[-2].minor.yy332.b = yymsp[0].minor.yy254;}
+        break;
+      case 236: /* when_clause ::= */
+      case 255: /* key_opt ::= */ yytestcase(yyruleno==255);
+{ yymsp[1].minor.yy72 = 0; }
+        break;
+      case 237: /* when_clause ::= WHEN expr */
+      case 256: /* key_opt ::= KEY expr */ yytestcase(yyruleno==256);
+{ yymsp[-1].minor.yy72 = yymsp[0].minor.yy190.pExpr; }
+        break;
+      case 238: /* trigger_cmd_list ::= trigger_cmd_list trigger_cmd SEMI */
+{
+  assert( yymsp[-2].minor.yy145!=0 );
+  yymsp[-2].minor.yy145->pLast->pNext = yymsp[-1].minor.yy145;
+  yymsp[-2].minor.yy145->pLast = yymsp[-1].minor.yy145;
+}
+        break;
+      case 239: /* trigger_cmd_list ::= trigger_cmd SEMI */
+{ 
+  assert( yymsp[-1].minor.yy145!=0 );
+  yymsp[-1].minor.yy145->pLast = yymsp[-1].minor.yy145;
+}
+        break;
+      case 240: /* trnm ::= nm DOT nm */
+{
+  yymsp[-2].minor.yy0 = yymsp[0].minor.yy0;
+  sqlite3ErrorMsg(pParse, 
+        "qualified table names are not allowed on INSERT, UPDATE, and DELETE "
+        "statements within triggers");
+}
+        break;
+      case 241: /* tridxby ::= INDEXED BY nm */
+{
+  sqlite3ErrorMsg(pParse,
+        "the INDEXED BY clause is not allowed on UPDATE or DELETE statements "
+        "within triggers");
+}
+        break;
+      case 242: /* tridxby ::= NOT INDEXED */
+{
+  sqlite3ErrorMsg(pParse,
+        "the NOT INDEXED clause is not allowed on UPDATE or DELETE statements "
+        "within triggers");
+}
+        break;
+      case 243: /* trigger_cmd ::= UPDATE orconf trnm tridxby SET setlist where_opt */
+{yymsp[-6].minor.yy145 = sqlite3TriggerUpdateStep(pParse->db, &yymsp[-4].minor.yy0, yymsp[-1].minor.yy148, yymsp[0].minor.yy72, yymsp[-5].minor.yy194);}
+        break;
+      case 244: /* trigger_cmd ::= insert_cmd INTO trnm idlist_opt select */
+{yymsp[-4].minor.yy145 = sqlite3TriggerInsertStep(pParse->db, &yymsp[-2].minor.yy0, yymsp[-1].minor.yy254, yymsp[0].minor.yy243, yymsp[-4].minor.yy194);/*A-overwrites-R*/}
+        break;
+      case 245: /* trigger_cmd ::= DELETE FROM trnm tridxby where_opt */
+{yymsp[-4].minor.yy145 = sqlite3TriggerDeleteStep(pParse->db, &yymsp[-2].minor.yy0, yymsp[0].minor.yy72);}
+        break;
+      case 246: /* trigger_cmd ::= select */
+{yymsp[0].minor.yy145 = sqlite3TriggerSelectStep(pParse->db, yymsp[0].minor.yy243); /*A-overwrites-X*/}
+        break;
+      case 247: /* expr ::= RAISE LP IGNORE RP */
+{
+  spanSet(&yymsp[-3].minor.yy190,&yymsp[-3].minor.yy0,&yymsp[0].minor.yy0);  /*A-overwrites-X*/
+  yymsp[-3].minor.yy190.pExpr = sqlite3PExpr(pParse, TK_RAISE, 0, 0, 0); 
+  if( yymsp[-3].minor.yy190.pExpr ){
+    yymsp[-3].minor.yy190.pExpr->affinity = OE_Ignore;
+  }
+}
+        break;
+      case 248: /* expr ::= RAISE LP raisetype COMMA nm RP */
+{
+  spanSet(&yymsp[-5].minor.yy190,&yymsp[-5].minor.yy0,&yymsp[0].minor.yy0);  /*A-overwrites-X*/
+  yymsp[-5].minor.yy190.pExpr = sqlite3PExpr(pParse, TK_RAISE, 0, 0, &yymsp[-1].minor.yy0); 
+  if( yymsp[-5].minor.yy190.pExpr ) {
+    yymsp[-5].minor.yy190.pExpr->affinity = (char)yymsp[-3].minor.yy194;
+  }
+}
+        break;
+      case 249: /* raisetype ::= ROLLBACK */
+{yymsp[0].minor.yy194 = OE_Rollback;}
+        break;
+      case 251: /* raisetype ::= FAIL */
+{yymsp[0].minor.yy194 = OE_Fail;}
+        break;
+      case 252: /* cmd ::= DROP TRIGGER ifexists fullname */
+{
+  sqlite3DropTrigger(pParse,yymsp[0].minor.yy185,yymsp[-1].minor.yy194);
+}
+        break;
+      case 253: /* cmd ::= ATTACH database_kw_opt expr AS expr key_opt */
+{
+  sqlite3Attach(pParse, yymsp[-3].minor.yy190.pExpr, yymsp[-1].minor.yy190.pExpr, yymsp[0].minor.yy72);
+}
+        break;
+      case 254: /* cmd ::= DETACH database_kw_opt expr */
+{
+  sqlite3Detach(pParse, yymsp[0].minor.yy190.pExpr);
+}
+        break;
+      case 257: /* cmd ::= REINDEX */
+{sqlite3Reindex(pParse, 0, 0);}
+        break;
+      case 258: /* cmd ::= REINDEX nm dbnm */
+{sqlite3Reindex(pParse, &yymsp[-1].minor.yy0, &yymsp[0].minor.yy0);}
+        break;
+      case 259: /* cmd ::= ANALYZE */
+{sqlite3Analyze(pParse, 0, 0);}
+        break;
+      case 260: /* cmd ::= ANALYZE nm dbnm */
+{sqlite3Analyze(pParse, &yymsp[-1].minor.yy0, &yymsp[0].minor.yy0);}
+        break;
+      case 261: /* cmd ::= ALTER TABLE fullname RENAME TO nm */
+{
+  sqlite3AlterRenameTable(pParse,yymsp[-3].minor.yy185,&yymsp[0].minor.yy0);
+}
+        break;
+      case 262: /* cmd ::= ALTER TABLE add_column_fullname ADD kwcolumn_opt columnname carglist */
+{
+  yymsp[-1].minor.yy0.n = (int)(pParse->sLastToken.z-yymsp[-1].minor.yy0.z) + pParse->sLastToken.n;
+  sqlite3AlterFinishAddColumn(pParse, &yymsp[-1].minor.yy0);
+}
+        break;
+      case 263: /* add_column_fullname ::= fullname */
+{
+  disableLookaside(pParse);
+  sqlite3AlterBeginAddColumn(pParse, yymsp[0].minor.yy185);
+}
+        break;
+      case 264: /* cmd ::= create_vtab */
+{sqlite3VtabFinishParse(pParse,0);}
+        break;
+      case 265: /* cmd ::= create_vtab LP vtabarglist RP */
+{sqlite3VtabFinishParse(pParse,&yymsp[0].minor.yy0);}
+        break;
+      case 266: /* create_vtab ::= createkw VIRTUAL TABLE ifnotexists nm dbnm USING nm */
+{
+    sqlite3VtabBeginParse(pParse, &yymsp[-3].minor.yy0, &yymsp[-2].minor.yy0, &yymsp[0].minor.yy0, yymsp[-4].minor.yy194);
+}
+        break;
+      case 267: /* vtabarg ::= */
+{sqlite3VtabArgInit(pParse);}
+        break;
+      case 268: /* vtabargtoken ::= ANY */
+      case 269: /* vtabargtoken ::= lp anylist RP */ yytestcase(yyruleno==269);
+      case 270: /* lp ::= LP */ yytestcase(yyruleno==270);
+{sqlite3VtabArgExtend(pParse,&yymsp[0].minor.yy0);}
+        break;
+      case 271: /* with ::= */
+{yymsp[1].minor.yy285 = 0;}
+        break;
+      case 272: /* with ::= WITH wqlist */
+{ yymsp[-1].minor.yy285 = yymsp[0].minor.yy285; }
+        break;
+      case 273: /* with ::= WITH RECURSIVE wqlist */
+{ yymsp[-2].minor.yy285 = yymsp[0].minor.yy285; }
+        break;
+      case 274: /* wqlist ::= nm eidlist_opt AS LP select RP */
+{
+  yymsp[-5].minor.yy285 = sqlite3WithAdd(pParse, 0, &yymsp[-5].minor.yy0, yymsp[-4].minor.yy148, yymsp[-1].minor.yy243); /*A-overwrites-X*/
+}
+        break;
+      case 275: /* wqlist ::= wqlist COMMA nm eidlist_opt AS LP select RP */
+{
+  yymsp[-7].minor.yy285 = sqlite3WithAdd(pParse, yymsp[-7].minor.yy285, &yymsp[-5].minor.yy0, yymsp[-4].minor.yy148, yymsp[-1].minor.yy243);
+}
+        break;
+      default:
+      /* (276) input ::= cmdlist */ yytestcase(yyruleno==276);
+      /* (277) cmdlist ::= cmdlist ecmd */ yytestcase(yyruleno==277);
+      /* (278) cmdlist ::= ecmd (OPTIMIZED OUT) */ assert(yyruleno!=278);
+      /* (279) ecmd ::= SEMI */ yytestcase(yyruleno==279);
+      /* (280) ecmd ::= explain cmdx SEMI */ yytestcase(yyruleno==280);
+      /* (281) explain ::= */ yytestcase(yyruleno==281);
+      /* (282) trans_opt ::= */ yytestcase(yyruleno==282);
+      /* (283) trans_opt ::= TRANSACTION */ yytestcase(yyruleno==283);
+      /* (284) trans_opt ::= TRANSACTION nm */ yytestcase(yyruleno==284);
+      /* (285) savepoint_opt ::= SAVEPOINT */ yytestcase(yyruleno==285);
+      /* (286) savepoint_opt ::= */ yytestcase(yyruleno==286);
+      /* (287) cmd ::= create_table create_table_args */ yytestcase(yyruleno==287);
+      /* (288) columnlist ::= columnlist COMMA columnname carglist */ yytestcase(yyruleno==288);
+      /* (289) columnlist ::= columnname carglist */ yytestcase(yyruleno==289);
+      /* (290) nm ::= ID|INDEXED */ yytestcase(yyruleno==290);
+      /* (291) nm ::= STRING */ yytestcase(yyruleno==291);
+      /* (292) nm ::= JOIN_KW */ yytestcase(yyruleno==292);
+      /* (293) typetoken ::= typename */ yytestcase(yyruleno==293);
+      /* (294) typename ::= ID|STRING */ yytestcase(yyruleno==294);
+      /* (295) signed ::= plus_num (OPTIMIZED OUT) */ assert(yyruleno!=295);
+      /* (296) signed ::= minus_num (OPTIMIZED OUT) */ assert(yyruleno!=296);
+      /* (297) carglist ::= carglist ccons */ yytestcase(yyruleno==297);
+      /* (298) carglist ::= */ yytestcase(yyruleno==298);
+      /* (299) ccons ::= NULL onconf */ yytestcase(yyruleno==299);
+      /* (300) conslist_opt ::= COMMA conslist */ yytestcase(yyruleno==300);
+      /* (301) conslist ::= conslist tconscomma tcons */ yytestcase(yyruleno==301);
+      /* (302) conslist ::= tcons (OPTIMIZED OUT) */ assert(yyruleno!=302);
+      /* (303) tconscomma ::= */ yytestcase(yyruleno==303);
+      /* (304) defer_subclause_opt ::= defer_subclause (OPTIMIZED OUT) */ assert(yyruleno!=304);
+      /* (305) resolvetype ::= raisetype (OPTIMIZED OUT) */ assert(yyruleno!=305);
+      /* (306) selectnowith ::= oneselect (OPTIMIZED OUT) */ assert(yyruleno!=306);
+      /* (307) oneselect ::= values */ yytestcase(yyruleno==307);
+      /* (308) sclp ::= selcollist COMMA */ yytestcase(yyruleno==308);
+      /* (309) as ::= ID|STRING */ yytestcase(yyruleno==309);
+      /* (310) expr ::= term (OPTIMIZED OUT) */ assert(yyruleno!=310);
+      /* (311) exprlist ::= nexprlist */ yytestcase(yyruleno==311);
+      /* (312) nmnum ::= plus_num (OPTIMIZED OUT) */ assert(yyruleno!=312);
+      /* (313) nmnum ::= nm (OPTIMIZED OUT) */ assert(yyruleno!=313);
+      /* (314) nmnum ::= ON */ yytestcase(yyruleno==314);
+      /* (315) nmnum ::= DELETE */ yytestcase(yyruleno==315);
+      /* (316) nmnum ::= DEFAULT */ yytestcase(yyruleno==316);
+      /* (317) plus_num ::= INTEGER|FLOAT */ yytestcase(yyruleno==317);
+      /* (318) foreach_clause ::= */ yytestcase(yyruleno==318);
+      /* (319) foreach_clause ::= FOR EACH ROW */ yytestcase(yyruleno==319);
+      /* (320) trnm ::= nm */ yytestcase(yyruleno==320);
+      /* (321) tridxby ::= */ yytestcase(yyruleno==321);
+      /* (322) database_kw_opt ::= DATABASE */ yytestcase(yyruleno==322);
+      /* (323) database_kw_opt ::= */ yytestcase(yyruleno==323);
+      /* (324) kwcolumn_opt ::= */ yytestcase(yyruleno==324);
+      /* (325) kwcolumn_opt ::= COLUMNKW */ yytestcase(yyruleno==325);
+      /* (326) vtabarglist ::= vtabarg */ yytestcase(yyruleno==326);
+      /* (327) vtabarglist ::= vtabarglist COMMA vtabarg */ yytestcase(yyruleno==327);
+      /* (328) vtabarg ::= vtabarg vtabargtoken */ yytestcase(yyruleno==328);
+      /* (329) anylist ::= */ yytestcase(yyruleno==329);
+      /* (330) anylist ::= anylist LP anylist RP */ yytestcase(yyruleno==330);
+      /* (331) anylist ::= anylist ANY */ yytestcase(yyruleno==331);
+        break;
+/********** End reduce actions ************************************************/
+  };
+  assert( yyruleno<sizeof(yyRuleInfo)/sizeof(yyRuleInfo[0]) );
+  yygoto = yyRuleInfo[yyruleno].lhs;
+  yysize = yyRuleInfo[yyruleno].nrhs;
+  yyact = yy_find_reduce_action(yymsp[-yysize].stateno,(YYCODETYPE)yygoto);
+  if( yyact <= YY_MAX_SHIFTREDUCE ){
+    if( yyact>YY_MAX_SHIFT ){
+      yyact += YY_MIN_REDUCE - YY_MIN_SHIFTREDUCE;
+    }
+    yymsp -= yysize-1;
+    yypParser->yytos = yymsp;
+    yymsp->stateno = (YYACTIONTYPE)yyact;
+    yymsp->major = (YYCODETYPE)yygoto;
+    yyTraceShift(yypParser, yyact);
+  }else{
+    assert( yyact == YY_ACCEPT_ACTION );
+    yypParser->yytos -= yysize;
+    yy_accept(yypParser);
+  }
+}
+
+/*
+** The following code executes when the parse fails
+*/
+#ifndef YYNOERRORRECOVERY
+static void yy_parse_failed(
+  yyParser *yypParser           /* The parser */
+){
+  sqlite3ParserARG_FETCH;
+#ifndef NDEBUG
+  if( yyTraceFILE ){
+    fprintf(yyTraceFILE,"%sFail!\n",yyTracePrompt);
+  }
+#endif
+  while( yypParser->yytos>yypParser->yystack ) yy_pop_parser_stack(yypParser);
+  /* Here code is inserted which will be executed whenever the
+  ** parser fails */
+/************ Begin %parse_failure code ***************************************/
+/************ End %parse_failure code *****************************************/
+  sqlite3ParserARG_STORE; /* Suppress warning about unused %extra_argument variable */
+}
+#endif /* YYNOERRORRECOVERY */
+
+/*
+** The following code executes when a syntax error first occurs.
+*/
+static void yy_syntax_error(
+  yyParser *yypParser,           /* The parser */
+  int yymajor,                   /* The major type of the error token */
+  sqlite3ParserTOKENTYPE yyminor         /* The minor type of the error token */
+){
+  sqlite3ParserARG_FETCH;
+#define TOKEN yyminor
+/************ Begin %syntax_error code ****************************************/
+
+  UNUSED_PARAMETER(yymajor);  /* Silence some compiler warnings */
+  assert( TOKEN.z[0] );  /* The tokenizer always gives us a token */
+  sqlite3ErrorMsg(pParse, "near \"%T\": syntax error", &TOKEN);
+/************ End %syntax_error code ******************************************/
+  sqlite3ParserARG_STORE; /* Suppress warning about unused %extra_argument variable */
+}
+
+/*
+** The following is executed when the parser accepts
+*/
+static void yy_accept(
+  yyParser *yypParser           /* The parser */
+){
+  sqlite3ParserARG_FETCH;
+#ifndef NDEBUG
+  if( yyTraceFILE ){
+    fprintf(yyTraceFILE,"%sAccept!\n",yyTracePrompt);
+  }
+#endif
+#ifndef YYNOERRORRECOVERY
+  yypParser->yyerrcnt = -1;
+#endif
+  assert( yypParser->yytos==yypParser->yystack );
+  /* Here code is inserted which will be executed whenever the
+  ** parser accepts */
+/*********** Begin %parse_accept code *****************************************/
+/*********** End %parse_accept code *******************************************/
+  sqlite3ParserARG_STORE; /* Suppress warning about unused %extra_argument variable */
+}
+
+/* The main parser program.
+** The first argument is a pointer to a structure obtained from
+** "sqlite3ParserAlloc" which describes the current state of the parser.
+** The second argument is the major token number.  The third is
+** the minor token.  The fourth optional argument is whatever the
+** user wants (and specified in the grammar) and is available for
+** use by the action routines.
+**
+** Inputs:
+** <ul>
+** <li> A pointer to the parser (an opaque structure.)
+** <li> The major token number.
+** <li> The minor token number.
+** <li> An option argument of a grammar-specified type.
+** </ul>
+**
+** Outputs:
+** None.
+*/
+SQLITE_PRIVATE void sqlite3Parser(
+  void *yyp,                   /* The parser */
+  int yymajor,                 /* The major token code number */
+  sqlite3ParserTOKENTYPE yyminor       /* The value for the token */
+  sqlite3ParserARG_PDECL               /* Optional %extra_argument parameter */
+){
+  YYMINORTYPE yyminorunion;
+  unsigned int yyact;   /* The parser action. */
+#if !defined(YYERRORSYMBOL) && !defined(YYNOERRORRECOVERY)
+  int yyendofinput;     /* True if we are at the end of input */
+#endif
+#ifdef YYERRORSYMBOL
+  int yyerrorhit = 0;   /* True if yymajor has invoked an error */
+#endif
+  yyParser *yypParser;  /* The parser */
+
+  yypParser = (yyParser*)yyp;
+  assert( yypParser->yytos!=0 );
+#if !defined(YYERRORSYMBOL) && !defined(YYNOERRORRECOVERY)
+  yyendofinput = (yymajor==0);
+#endif
+  sqlite3ParserARG_STORE;
+
+#ifndef NDEBUG
+  if( yyTraceFILE ){
+    fprintf(yyTraceFILE,"%sInput '%s'\n",yyTracePrompt,yyTokenName[yymajor]);
+  }
+#endif
+
+  do{
+    yyact = yy_find_shift_action(yypParser,(YYCODETYPE)yymajor);
+    if( yyact <= YY_MAX_SHIFTREDUCE ){
+      yy_shift(yypParser,yyact,yymajor,yyminor);
+#ifndef YYNOERRORRECOVERY
+      yypParser->yyerrcnt--;
+#endif
+      yymajor = YYNOCODE;
+    }else if( yyact <= YY_MAX_REDUCE ){
+      yy_reduce(yypParser,yyact-YY_MIN_REDUCE);
+    }else{
+      assert( yyact == YY_ERROR_ACTION );
+      yyminorunion.yy0 = yyminor;
+#ifdef YYERRORSYMBOL
+      int yymx;
+#endif
+#ifndef NDEBUG
+      if( yyTraceFILE ){
+        fprintf(yyTraceFILE,"%sSyntax Error!\n",yyTracePrompt);
+      }
+#endif
+#ifdef YYERRORSYMBOL
+      /* A syntax error has occurred.
+      ** The response to an error depends upon whether or not the
+      ** grammar defines an error token "ERROR".  
+      **
+      ** This is what we do if the grammar does define ERROR:
+      **
+      **  * Call the %syntax_error function.
+      **
+      **  * Begin popping the stack until we enter a state where
+      **    it is legal to shift the error symbol, then shift
+      **    the error symbol.
+      **
+      **  * Set the error count to three.
+      **
+      **  * Begin accepting and shifting new tokens.  No new error
+      **    processing will occur until three tokens have been
+      **    shifted successfully.
+      **
+      */
+      if( yypParser->yyerrcnt<0 ){
+        yy_syntax_error(yypParser,yymajor,yyminor);
+      }
+      yymx = yypParser->yytos->major;
+      if( yymx==YYERRORSYMBOL || yyerrorhit ){
+#ifndef NDEBUG
+        if( yyTraceFILE ){
+          fprintf(yyTraceFILE,"%sDiscard input token %s\n",
+             yyTracePrompt,yyTokenName[yymajor]);
+        }
+#endif
+        yy_destructor(yypParser, (YYCODETYPE)yymajor, &yyminorunion);
+        yymajor = YYNOCODE;
+      }else{
+        while( yypParser->yytos >= yypParser->yystack
+            && yymx != YYERRORSYMBOL
+            && (yyact = yy_find_reduce_action(
+                        yypParser->yytos->stateno,
+                        YYERRORSYMBOL)) >= YY_MIN_REDUCE
+        ){
+          yy_pop_parser_stack(yypParser);
+        }
+        if( yypParser->yytos < yypParser->yystack || yymajor==0 ){
+          yy_destructor(yypParser,(YYCODETYPE)yymajor,&yyminorunion);
+          yy_parse_failed(yypParser);
+#ifndef YYNOERRORRECOVERY
+          yypParser->yyerrcnt = -1;
+#endif
+          yymajor = YYNOCODE;
+        }else if( yymx!=YYERRORSYMBOL ){
+          yy_shift(yypParser,yyact,YYERRORSYMBOL,yyminor);
+        }
+      }
+      yypParser->yyerrcnt = 3;
+      yyerrorhit = 1;
+#elif defined(YYNOERRORRECOVERY)
+      /* If the YYNOERRORRECOVERY macro is defined, then do not attempt to
+      ** do any kind of error recovery.  Instead, simply invoke the syntax
+      ** error routine and continue going as if nothing had happened.
+      **
+      ** Applications can set this macro (for example inside %include) if
+      ** they intend to abandon the parse upon the first syntax error seen.
+      */
+      yy_syntax_error(yypParser,yymajor, yyminor);
+      yy_destructor(yypParser,(YYCODETYPE)yymajor,&yyminorunion);
+      yymajor = YYNOCODE;
+      
+#else  /* YYERRORSYMBOL is not defined */
+      /* This is what we do if the grammar does not define ERROR:
+      **
+      **  * Report an error message, and throw away the input token.
+      **
+      **  * If the input token is $, then fail the parse.
+      **
+      ** As before, subsequent error messages are suppressed until
+      ** three input tokens have been successfully shifted.
+      */
+      if( yypParser->yyerrcnt<=0 ){
+        yy_syntax_error(yypParser,yymajor, yyminor);
+      }
+      yypParser->yyerrcnt = 3;
+      yy_destructor(yypParser,(YYCODETYPE)yymajor,&yyminorunion);
+      if( yyendofinput ){
+        yy_parse_failed(yypParser);
+#ifndef YYNOERRORRECOVERY
+        yypParser->yyerrcnt = -1;
+#endif
+      }
+      yymajor = YYNOCODE;
+#endif
+    }
+  }while( yymajor!=YYNOCODE && yypParser->yytos>yypParser->yystack );
+#ifndef NDEBUG
+  if( yyTraceFILE ){
+    yyStackEntry *i;
+    char cDiv = '[';
+    fprintf(yyTraceFILE,"%sReturn. Stack=",yyTracePrompt);
+    for(i=&yypParser->yystack[1]; i<=yypParser->yytos; i++){
+      fprintf(yyTraceFILE,"%c%s", cDiv, yyTokenName[i->major]);
+      cDiv = ' ';
+    }
+    fprintf(yyTraceFILE,"]\n");
+  }
+#endif
+  return;
+}
+
+/************** End of parse.c ***********************************************/
+/************** Begin file tokenize.c ****************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** An tokenizer for SQL
+**
+** This file contains C code that splits an SQL input string up into
+** individual tokens and sends those tokens one-by-one over to the
+** parser for analysis.
+*/
+/* #include "sqliteInt.h" */
+/* #include <stdlib.h> */
+
+/* Character classes for tokenizing
+**
+** In the sqlite3GetToken() function, a switch() on aiClass[c] is implemented
+** using a lookup table, whereas a switch() directly on c uses a binary search.
+** The lookup table is much faster.  To maximize speed, and to ensure that
+** a lookup table is used, all of the classes need to be small integers and
+** all of them need to be used within the switch.
+*/
+#define CC_X          0    /* The letter 'x', or start of BLOB literal */
+#define CC_KYWD       1    /* Alphabetics or '_'.  Usable in a keyword */
+#define CC_ID         2    /* unicode characters usable in IDs */
+#define CC_DIGIT      3    /* Digits */
+#define CC_DOLLAR     4    /* '$' */
+#define CC_VARALPHA   5    /* '@', '#', ':'.  Alphabetic SQL variables */
+#define CC_VARNUM     6    /* '?'.  Numeric SQL variables */
+#define CC_SPACE      7    /* Space characters */
+#define CC_QUOTE      8    /* '"', '\'', or '`'.  String literals, quoted ids */
+#define CC_QUOTE2     9    /* '['.   [...] style quoted ids */
+#define CC_PIPE      10    /* '|'.   Bitwise OR or concatenate */
+#define CC_MINUS     11    /* '-'.  Minus or SQL-style comment */
+#define CC_LT        12    /* '<'.  Part of < or <= or <> */
+#define CC_GT        13    /* '>'.  Part of > or >= */
+#define CC_EQ        14    /* '='.  Part of = or == */
+#define CC_BANG      15    /* '!'.  Part of != */
+#define CC_SLASH     16    /* '/'.  / or c-style comment */
+#define CC_LP        17    /* '(' */
+#define CC_RP        18    /* ')' */
+#define CC_SEMI      19    /* ';' */
+#define CC_PLUS      20    /* '+' */
+#define CC_STAR      21    /* '*' */
+#define CC_PERCENT   22    /* '%' */
+#define CC_COMMA     23    /* ',' */
+#define CC_AND       24    /* '&' */
+#define CC_TILDA     25    /* '~' */
+#define CC_DOT       26    /* '.' */
+#define CC_ILLEGAL   27    /* Illegal character */
+
+static const unsigned char aiClass[] = {
+#ifdef SQLITE_ASCII
+/*         x0  x1  x2  x3  x4  x5  x6  x7  x8  x9  xa  xb  xc  xd  xe  xf */
+/* 0x */   27, 27, 27, 27, 27, 27, 27, 27, 27,  7,  7, 27,  7,  7, 27, 27,
+/* 1x */   27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
+/* 2x */    7, 15,  8,  5,  4, 22, 24,  8, 17, 18, 21, 20, 23, 11, 26, 16,
+/* 3x */    3,  3,  3,  3,  3,  3,  3,  3,  3,  3,  5, 19, 12, 14, 13,  6,
+/* 4x */    5,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
+/* 5x */    1,  1,  1,  1,  1,  1,  1,  1,  0,  1,  1,  9, 27, 27, 27,  1,
+/* 6x */    8,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
+/* 7x */    1,  1,  1,  1,  1,  1,  1,  1,  0,  1,  1, 27, 10, 27, 25, 27,
+/* 8x */    2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,
+/* 9x */    2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,
+/* Ax */    2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,
+/* Bx */    2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,
+/* Cx */    2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,
+/* Dx */    2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,
+/* Ex */    2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,
+/* Fx */    2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2
+#endif
+#ifdef SQLITE_EBCDIC
+/*         x0  x1  x2  x3  x4  x5  x6  x7  x8  x9  xa  xb  xc  xd  xe  xf */
+/* 0x */   27, 27, 27, 27, 27,  7, 27, 27, 27, 27, 27, 27,  7,  7, 27, 27,
+/* 1x */   27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
+/* 2x */   27, 27, 27, 27, 27,  7, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
+/* 3x */   27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
+/* 4x */    7, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 12, 17, 20, 10,
+/* 5x */   24, 27, 27, 27, 27, 27, 27, 27, 27, 27, 15,  4, 21, 18, 19, 27,
+/* 6x */   11, 16, 27, 27, 27, 27, 27, 27, 27, 27, 27, 23, 22,  1, 13,  7,
+/* 7x */   27, 27, 27, 27, 27, 27, 27, 27, 27,  8,  5,  5,  5,  8, 14,  8,
+/* 8x */   27,  1,  1,  1,  1,  1,  1,  1,  1,  1, 27, 27, 27, 27, 27, 27,
+/* 9x */   27,  1,  1,  1,  1,  1,  1,  1,  1,  1, 27, 27, 27, 27, 27, 27,
+/* 9x */   25,  1,  1,  1,  1,  1,  1,  0,  1,  1, 27, 27, 27, 27, 27, 27,
+/* Bx */   27, 27, 27, 27, 27, 27, 27, 27, 27, 27,  9, 27, 27, 27, 27, 27,
+/* Cx */   27,  1,  1,  1,  1,  1,  1,  1,  1,  1, 27, 27, 27, 27, 27, 27,
+/* Dx */   27,  1,  1,  1,  1,  1,  1,  1,  1,  1, 27, 27, 27, 27, 27, 27,
+/* Ex */   27, 27,  1,  1,  1,  1,  1,  0,  1,  1, 27, 27, 27, 27, 27, 27,
+/* Fx */    3,  3,  3,  3,  3,  3,  3,  3,  3,  3, 27, 27, 27, 27, 27, 27,
+#endif
+};
+
+/*
+** The charMap() macro maps alphabetic characters (only) into their
+** lower-case ASCII equivalent.  On ASCII machines, this is just
+** an upper-to-lower case map.  On EBCDIC machines we also need
+** to adjust the encoding.  The mapping is only valid for alphabetics
+** which are the only characters for which this feature is used. 
+**
+** Used by keywordhash.h
+*/
+#ifdef SQLITE_ASCII
+# define charMap(X) sqlite3UpperToLower[(unsigned char)X]
+#endif
+#ifdef SQLITE_EBCDIC
+# define charMap(X) ebcdicToAscii[(unsigned char)X]
+const unsigned char ebcdicToAscii[] = {
+/* 0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F */
+   0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  /* 0x */
+   0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  /* 1x */
+   0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  /* 2x */
+   0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  /* 3x */
+   0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  /* 4x */
+   0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  /* 5x */
+   0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 95,  0,  0,  /* 6x */
+   0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  /* 7x */
+   0, 97, 98, 99,100,101,102,103,104,105,  0,  0,  0,  0,  0,  0,  /* 8x */
+   0,106,107,108,109,110,111,112,113,114,  0,  0,  0,  0,  0,  0,  /* 9x */
+   0,  0,115,116,117,118,119,120,121,122,  0,  0,  0,  0,  0,  0,  /* Ax */
+   0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  /* Bx */
+   0, 97, 98, 99,100,101,102,103,104,105,  0,  0,  0,  0,  0,  0,  /* Cx */
+   0,106,107,108,109,110,111,112,113,114,  0,  0,  0,  0,  0,  0,  /* Dx */
+   0,  0,115,116,117,118,119,120,121,122,  0,  0,  0,  0,  0,  0,  /* Ex */
+   0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  /* Fx */
+};
+#endif
+
+/*
+** The sqlite3KeywordCode function looks up an identifier to determine if
+** it is a keyword.  If it is a keyword, the token code of that keyword is 
+** returned.  If the input is not a keyword, TK_ID is returned.
+**
+** The implementation of this routine was generated by a program,
+** mkkeywordhash.c, located in the tool subdirectory of the distribution.
+** The output of the mkkeywordhash.c program is written into a file
+** named keywordhash.h and then included into this source file by
+** the #include below.
+*/
+/************** Include keywordhash.h in the middle of tokenize.c ************/
+/************** Begin file keywordhash.h *************************************/
+/***** This file contains automatically generated code ******
+**
+** The code in this file has been automatically generated by
+**
+**   sqlite/tool/mkkeywordhash.c
+**
+** The code in this file implements a function that determines whether
+** or not a given identifier is really an SQL keyword.  The same thing
+** might be implemented more directly using a hand-written hash table.
+** But by using this automatically generated code, the size of the code
+** is substantially reduced.  This is important for embedded applications
+** on platforms with limited memory.
+*/
+/* Hash score: 182 */
+static int keywordCode(const char *z, int n, int *pType){
+  /* zText[] encodes 834 bytes of keywords in 554 bytes */
+  /*   REINDEXEDESCAPEACHECKEYBEFOREIGNOREGEXPLAINSTEADDATABASELECT       */
+  /*   ABLEFTHENDEFERRABLELSEXCEPTRANSACTIONATURALTERAISEXCLUSIVE         */
+  /*   XISTSAVEPOINTERSECTRIGGEREFERENCESCONSTRAINTOFFSETEMPORARY         */
+  /*   UNIQUERYWITHOUTERELEASEATTACHAVINGROUPDATEBEGINNERECURSIVE         */
+  /*   BETWEENOTNULLIKECASCADELETECASECOLLATECREATECURRENT_DATEDETACH     */
+  /*   IMMEDIATEJOINSERTMATCHPLANALYZEPRAGMABORTVALUESVIRTUALIMITWHEN     */
+  /*   WHERENAMEAFTEREPLACEANDEFAULTAUTOINCREMENTCASTCOLUMNCOMMIT         */
+  /*   CONFLICTCROSSCURRENT_TIMESTAMPRIMARYDEFERREDISTINCTDROPFAIL        */
+  /*   FROMFULLGLOBYIFISNULLORDERESTRICTRIGHTROLLBACKROWUNIONUSING        */
+  /*   VACUUMVIEWINITIALLY                                                */
+  static const char zText[553] = {
+    'R','E','I','N','D','E','X','E','D','E','S','C','A','P','E','A','C','H',
+    'E','C','K','E','Y','B','E','F','O','R','E','I','G','N','O','R','E','G',
+    'E','X','P','L','A','I','N','S','T','E','A','D','D','A','T','A','B','A',
+    'S','E','L','E','C','T','A','B','L','E','F','T','H','E','N','D','E','F',
+    'E','R','R','A','B','L','E','L','S','E','X','C','E','P','T','R','A','N',
+    'S','A','C','T','I','O','N','A','T','U','R','A','L','T','E','R','A','I',
+    'S','E','X','C','L','U','S','I','V','E','X','I','S','T','S','A','V','E',
+    'P','O','I','N','T','E','R','S','E','C','T','R','I','G','G','E','R','E',
+    'F','E','R','E','N','C','E','S','C','O','N','S','T','R','A','I','N','T',
+    'O','F','F','S','E','T','E','M','P','O','R','A','R','Y','U','N','I','Q',
+    'U','E','R','Y','W','I','T','H','O','U','T','E','R','E','L','E','A','S',
+    'E','A','T','T','A','C','H','A','V','I','N','G','R','O','U','P','D','A',
+    'T','E','B','E','G','I','N','N','E','R','E','C','U','R','S','I','V','E',
+    'B','E','T','W','E','E','N','O','T','N','U','L','L','I','K','E','C','A',
+    'S','C','A','D','E','L','E','T','E','C','A','S','E','C','O','L','L','A',
+    'T','E','C','R','E','A','T','E','C','U','R','R','E','N','T','_','D','A',
+    'T','E','D','E','T','A','C','H','I','M','M','E','D','I','A','T','E','J',
+    'O','I','N','S','E','R','T','M','A','T','C','H','P','L','A','N','A','L',
+    'Y','Z','E','P','R','A','G','M','A','B','O','R','T','V','A','L','U','E',
+    'S','V','I','R','T','U','A','L','I','M','I','T','W','H','E','N','W','H',
+    'E','R','E','N','A','M','E','A','F','T','E','R','E','P','L','A','C','E',
+    'A','N','D','E','F','A','U','L','T','A','U','T','O','I','N','C','R','E',
+    'M','E','N','T','C','A','S','T','C','O','L','U','M','N','C','O','M','M',
+    'I','T','C','O','N','F','L','I','C','T','C','R','O','S','S','C','U','R',
+    'R','E','N','T','_','T','I','M','E','S','T','A','M','P','R','I','M','A',
+    'R','Y','D','E','F','E','R','R','E','D','I','S','T','I','N','C','T','D',
+    'R','O','P','F','A','I','L','F','R','O','M','F','U','L','L','G','L','O',
+    'B','Y','I','F','I','S','N','U','L','L','O','R','D','E','R','E','S','T',
+    'R','I','C','T','R','I','G','H','T','R','O','L','L','B','A','C','K','R',
+    'O','W','U','N','I','O','N','U','S','I','N','G','V','A','C','U','U','M',
+    'V','I','E','W','I','N','I','T','I','A','L','L','Y',
+  };
+  static const unsigned char aHash[127] = {
+      76, 105, 117,  74,   0,  45,   0,   0,  82,   0,  77,   0,   0,
+      42,  12,  78,  15,   0, 116,  85,  54, 112,   0,  19,   0,   0,
+     121,   0, 119, 115,   0,  22,  93,   0,   9,   0,   0,  70,  71,
+       0,  69,   6,   0,  48,  90, 102,   0, 118, 101,   0,   0,  44,
+       0, 103,  24,   0,  17,   0, 122,  53,  23,   0,   5, 110,  25,
+      96,   0,   0, 124, 106,  60, 123,  57,  28,  55,   0,  91,   0,
+     100,  26,   0,  99,   0,   0,   0,  95,  92,  97,  88, 109,  14,
+      39, 108,   0,  81,   0,  18,  89, 111,  32,   0, 120,  80, 113,
+      62,  46,  84,   0,   0,  94,  40,  59, 114,   0,  36,   0,   0,
+      29,   0,  86,  63,  64,   0,  20,  61,   0,  56,
+  };
+  static const unsigned char aNext[124] = {
+       0,   0,   0,   0,   4,   0,   0,   0,   0,   0,   0,   0,   0,
+       0,   2,   0,   0,   0,   0,   0,   0,  13,   0,   0,   0,   0,
+       0,   7,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
+       0,   0,   0,   0,  33,   0,  21,   0,   0,   0,   0,   0,  50,
+       0,  43,   3,  47,   0,   0,   0,   0,  30,   0,  58,   0,  38,
+       0,   0,   0,   1,  66,   0,   0,  67,   0,  41,   0,   0,   0,
+       0,   0,   0,  49,  65,   0,   0,   0,   0,  31,  52,  16,  34,
+      10,   0,   0,   0,   0,   0,   0,   0,  11,  72,  79,   0,   8,
+       0, 104,  98,   0, 107,   0,  87,   0,  75,  51,   0,  27,  37,
+      73,  83,   0,  35,  68,   0,   0,
+  };
+  static const unsigned char aLen[124] = {
+       7,   7,   5,   4,   6,   4,   5,   3,   6,   7,   3,   6,   6,
+       7,   7,   3,   8,   2,   6,   5,   4,   4,   3,  10,   4,   6,
+      11,   6,   2,   7,   5,   5,   9,   6,   9,   9,   7,  10,  10,
+       4,   6,   2,   3,   9,   4,   2,   6,   5,   7,   4,   5,   7,
+       6,   6,   5,   6,   5,   5,   9,   7,   7,   3,   2,   4,   4,
+       7,   3,   6,   4,   7,   6,  12,   6,   9,   4,   6,   5,   4,
+       7,   6,   5,   6,   7,   5,   4,   5,   6,   5,   7,   3,   7,
+      13,   2,   2,   4,   6,   6,   8,   5,  17,  12,   7,   8,   8,
+       2,   4,   4,   4,   4,   4,   2,   2,   6,   5,   8,   5,   8,
+       3,   5,   5,   6,   4,   9,   3,
+  };
+  static const unsigned short int aOffset[124] = {
+       0,   2,   2,   8,   9,  14,  16,  20,  23,  25,  25,  29,  33,
+      36,  41,  46,  48,  53,  54,  59,  62,  65,  67,  69,  78,  81,
+      86,  91,  95,  96, 101, 105, 109, 117, 122, 128, 136, 142, 152,
+     159, 162, 162, 165, 167, 167, 171, 176, 179, 184, 184, 188, 192,
+     199, 204, 209, 212, 218, 221, 225, 234, 240, 240, 240, 243, 246,
+     250, 251, 255, 261, 265, 272, 278, 290, 296, 305, 307, 313, 318,
+     320, 327, 332, 337, 343, 349, 354, 358, 361, 367, 371, 378, 380,
+     387, 389, 391, 400, 404, 410, 416, 424, 429, 429, 445, 452, 459,
+     460, 467, 471, 475, 479, 483, 486, 488, 490, 496, 500, 508, 513,
+     521, 524, 529, 534, 540, 544, 549,
+  };
+  static const unsigned char aCode[124] = {
+    TK_REINDEX,    TK_INDEXED,    TK_INDEX,      TK_DESC,       TK_ESCAPE,     
+    TK_EACH,       TK_CHECK,      TK_KEY,        TK_BEFORE,     TK_FOREIGN,    
+    TK_FOR,        TK_IGNORE,     TK_LIKE_KW,    TK_EXPLAIN,    TK_INSTEAD,    
+    TK_ADD,        TK_DATABASE,   TK_AS,         TK_SELECT,     TK_TABLE,      
+    TK_JOIN_KW,    TK_THEN,       TK_END,        TK_DEFERRABLE, TK_ELSE,       
+    TK_EXCEPT,     TK_TRANSACTION,TK_ACTION,     TK_ON,         TK_JOIN_KW,    
+    TK_ALTER,      TK_RAISE,      TK_EXCLUSIVE,  TK_EXISTS,     TK_SAVEPOINT,  
+    TK_INTERSECT,  TK_TRIGGER,    TK_REFERENCES, TK_CONSTRAINT, TK_INTO,       
+    TK_OFFSET,     TK_OF,         TK_SET,        TK_TEMP,       TK_TEMP,       
+    TK_OR,         TK_UNIQUE,     TK_QUERY,      TK_WITHOUT,    TK_WITH,       
+    TK_JOIN_KW,    TK_RELEASE,    TK_ATTACH,     TK_HAVING,     TK_GROUP,      
+    TK_UPDATE,     TK_BEGIN,      TK_JOIN_KW,    TK_RECURSIVE,  TK_BETWEEN,    
+    TK_NOTNULL,    TK_NOT,        TK_NO,         TK_NULL,       TK_LIKE_KW,    
+    TK_CASCADE,    TK_ASC,        TK_DELETE,     TK_CASE,       TK_COLLATE,    
+    TK_CREATE,     TK_CTIME_KW,   TK_DETACH,     TK_IMMEDIATE,  TK_JOIN,       
+    TK_INSERT,     TK_MATCH,      TK_PLAN,       TK_ANALYZE,    TK_PRAGMA,     
+    TK_ABORT,      TK_VALUES,     TK_VIRTUAL,    TK_LIMIT,      TK_WHEN,       
+    TK_WHERE,      TK_RENAME,     TK_AFTER,      TK_REPLACE,    TK_AND,        
+    TK_DEFAULT,    TK_AUTOINCR,   TK_TO,         TK_IN,         TK_CAST,       
+    TK_COLUMNKW,   TK_COMMIT,     TK_CONFLICT,   TK_JOIN_KW,    TK_CTIME_KW,   
+    TK_CTIME_KW,   TK_PRIMARY,    TK_DEFERRED,   TK_DISTINCT,   TK_IS,         
+    TK_DROP,       TK_FAIL,       TK_FROM,       TK_JOIN_KW,    TK_LIKE_KW,    
+    TK_BY,         TK_IF,         TK_ISNULL,     TK_ORDER,      TK_RESTRICT,   
+    TK_JOIN_KW,    TK_ROLLBACK,   TK_ROW,        TK_UNION,      TK_USING,      
+    TK_VACUUM,     TK_VIEW,       TK_INITIALLY,  TK_ALL,        
+  };
+  int i, j;
+  const char *zKW;
+  if( n>=2 ){
+    i = ((charMap(z[0])*4) ^ (charMap(z[n-1])*3) ^ n) % 127;
+    for(i=((int)aHash[i])-1; i>=0; i=((int)aNext[i])-1){
+      if( aLen[i]!=n ) continue;
+      j = 0;
+      zKW = &zText[aOffset[i]];
+#ifdef SQLITE_ASCII
+      while( j<n && (z[j]&~0x20)==zKW[j] ){ j++; }
+#endif
+#ifdef SQLITE_EBCDIC
+      while( j<n && toupper(z[j])==zKW[j] ){ j++; }
+#endif
+      if( j<n ) continue;
+      testcase( i==0 ); /* REINDEX */
+      testcase( i==1 ); /* INDEXED */
+      testcase( i==2 ); /* INDEX */
+      testcase( i==3 ); /* DESC */
+      testcase( i==4 ); /* ESCAPE */
+      testcase( i==5 ); /* EACH */
+      testcase( i==6 ); /* CHECK */
+      testcase( i==7 ); /* KEY */
+      testcase( i==8 ); /* BEFORE */
+      testcase( i==9 ); /* FOREIGN */
+      testcase( i==10 ); /* FOR */
+      testcase( i==11 ); /* IGNORE */
+      testcase( i==12 ); /* REGEXP */
+      testcase( i==13 ); /* EXPLAIN */
+      testcase( i==14 ); /* INSTEAD */
+      testcase( i==15 ); /* ADD */
+      testcase( i==16 ); /* DATABASE */
+      testcase( i==17 ); /* AS */
+      testcase( i==18 ); /* SELECT */
+      testcase( i==19 ); /* TABLE */
+      testcase( i==20 ); /* LEFT */
+      testcase( i==21 ); /* THEN */
+      testcase( i==22 ); /* END */
+      testcase( i==23 ); /* DEFERRABLE */
+      testcase( i==24 ); /* ELSE */
+      testcase( i==25 ); /* EXCEPT */
+      testcase( i==26 ); /* TRANSACTION */
+      testcase( i==27 ); /* ACTION */
+      testcase( i==28 ); /* ON */
+      testcase( i==29 ); /* NATURAL */
+      testcase( i==30 ); /* ALTER */
+      testcase( i==31 ); /* RAISE */
+      testcase( i==32 ); /* EXCLUSIVE */
+      testcase( i==33 ); /* EXISTS */
+      testcase( i==34 ); /* SAVEPOINT */
+      testcase( i==35 ); /* INTERSECT */
+      testcase( i==36 ); /* TRIGGER */
+      testcase( i==37 ); /* REFERENCES */
+      testcase( i==38 ); /* CONSTRAINT */
+      testcase( i==39 ); /* INTO */
+      testcase( i==40 ); /* OFFSET */
+      testcase( i==41 ); /* OF */
+      testcase( i==42 ); /* SET */
+      testcase( i==43 ); /* TEMPORARY */
+      testcase( i==44 ); /* TEMP */
+      testcase( i==45 ); /* OR */
+      testcase( i==46 ); /* UNIQUE */
+      testcase( i==47 ); /* QUERY */
+      testcase( i==48 ); /* WITHOUT */
+      testcase( i==49 ); /* WITH */
+      testcase( i==50 ); /* OUTER */
+      testcase( i==51 ); /* RELEASE */
+      testcase( i==52 ); /* ATTACH */
+      testcase( i==53 ); /* HAVING */
+      testcase( i==54 ); /* GROUP */
+      testcase( i==55 ); /* UPDATE */
+      testcase( i==56 ); /* BEGIN */
+      testcase( i==57 ); /* INNER */
+      testcase( i==58 ); /* RECURSIVE */
+      testcase( i==59 ); /* BETWEEN */
+      testcase( i==60 ); /* NOTNULL */
+      testcase( i==61 ); /* NOT */
+      testcase( i==62 ); /* NO */
+      testcase( i==63 ); /* NULL */
+      testcase( i==64 ); /* LIKE */
+      testcase( i==65 ); /* CASCADE */
+      testcase( i==66 ); /* ASC */
+      testcase( i==67 ); /* DELETE */
+      testcase( i==68 ); /* CASE */
+      testcase( i==69 ); /* COLLATE */
+      testcase( i==70 ); /* CREATE */
+      testcase( i==71 ); /* CURRENT_DATE */
+      testcase( i==72 ); /* DETACH */
+      testcase( i==73 ); /* IMMEDIATE */
+      testcase( i==74 ); /* JOIN */
+      testcase( i==75 ); /* INSERT */
+      testcase( i==76 ); /* MATCH */
+      testcase( i==77 ); /* PLAN */
+      testcase( i==78 ); /* ANALYZE */
+      testcase( i==79 ); /* PRAGMA */
+      testcase( i==80 ); /* ABORT */
+      testcase( i==81 ); /* VALUES */
+      testcase( i==82 ); /* VIRTUAL */
+      testcase( i==83 ); /* LIMIT */
+      testcase( i==84 ); /* WHEN */
+      testcase( i==85 ); /* WHERE */
+      testcase( i==86 ); /* RENAME */
+      testcase( i==87 ); /* AFTER */
+      testcase( i==88 ); /* REPLACE */
+      testcase( i==89 ); /* AND */
+      testcase( i==90 ); /* DEFAULT */
+      testcase( i==91 ); /* AUTOINCREMENT */
+      testcase( i==92 ); /* TO */
+      testcase( i==93 ); /* IN */
+      testcase( i==94 ); /* CAST */
+      testcase( i==95 ); /* COLUMN */
+      testcase( i==96 ); /* COMMIT */
+      testcase( i==97 ); /* CONFLICT */
+      testcase( i==98 ); /* CROSS */
+      testcase( i==99 ); /* CURRENT_TIMESTAMP */
+      testcase( i==100 ); /* CURRENT_TIME */
+      testcase( i==101 ); /* PRIMARY */
+      testcase( i==102 ); /* DEFERRED */
+      testcase( i==103 ); /* DISTINCT */
+      testcase( i==104 ); /* IS */
+      testcase( i==105 ); /* DROP */
+      testcase( i==106 ); /* FAIL */
+      testcase( i==107 ); /* FROM */
+      testcase( i==108 ); /* FULL */
+      testcase( i==109 ); /* GLOB */
+      testcase( i==110 ); /* BY */
+      testcase( i==111 ); /* IF */
+      testcase( i==112 ); /* ISNULL */
+      testcase( i==113 ); /* ORDER */
+      testcase( i==114 ); /* RESTRICT */
+      testcase( i==115 ); /* RIGHT */
+      testcase( i==116 ); /* ROLLBACK */
+      testcase( i==117 ); /* ROW */
+      testcase( i==118 ); /* UNION */
+      testcase( i==119 ); /* USING */
+      testcase( i==120 ); /* VACUUM */
+      testcase( i==121 ); /* VIEW */
+      testcase( i==122 ); /* INITIALLY */
+      testcase( i==123 ); /* ALL */
+      *pType = aCode[i];
+      break;
+    }
+  }
+  return n;
+}
+SQLITE_PRIVATE int sqlite3KeywordCode(const unsigned char *z, int n){
+  int id = TK_ID;
+  keywordCode((char*)z, n, &id);
+  return id;
+}
+#define SQLITE_N_KEYWORD 124
+
+/************** End of keywordhash.h *****************************************/
+/************** Continuing where we left off in tokenize.c *******************/
+
+
+/*
+** If X is a character that can be used in an identifier then
+** IdChar(X) will be true.  Otherwise it is false.
+**
+** For ASCII, any character with the high-order bit set is
+** allowed in an identifier.  For 7-bit characters, 
+** sqlite3IsIdChar[X] must be 1.
+**
+** For EBCDIC, the rules are more complex but have the same
+** end result.
+**
+** Ticket #1066.  the SQL standard does not allow '$' in the
+** middle of identifiers.  But many SQL implementations do. 
+** SQLite will allow '$' in identifiers for compatibility.
+** But the feature is undocumented.
+*/
+#ifdef SQLITE_ASCII
+#define IdChar(C)  ((sqlite3CtypeMap[(unsigned char)C]&0x46)!=0)
+#endif
+#ifdef SQLITE_EBCDIC
+SQLITE_PRIVATE const char sqlite3IsEbcdicIdChar[] = {
+/* x0 x1 x2 x3 x4 x5 x6 x7 x8 x9 xA xB xC xD xE xF */
+    0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0,  /* 4x */
+    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0,  /* 5x */
+    0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0,  /* 6x */
+    0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0,  /* 7x */
+    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 0,  /* 8x */
+    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 1, 0,  /* 9x */
+    1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0,  /* Ax */
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  /* Bx */
+    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1,  /* Cx */
+    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1,  /* Dx */
+    0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1,  /* Ex */
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0,  /* Fx */
+};
+#define IdChar(C)  (((c=C)>=0x42 && sqlite3IsEbcdicIdChar[c-0x40]))
+#endif
+
+/* Make the IdChar function accessible from ctime.c */
+#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
+SQLITE_PRIVATE int sqlite3IsIdChar(u8 c){ return IdChar(c); }
+#endif
+
+
+/*
+** Return the length (in bytes) of the token that begins at z[0]. 
+** Store the token type in *tokenType before returning.
+*/
+SQLITE_PRIVATE int sqlite3GetToken(const unsigned char *z, int *tokenType){
+  int i, c;
+  switch( aiClass[*z] ){  /* Switch on the character-class of the first byte
+                          ** of the token. See the comment on the CC_ defines
+                          ** above. */
+    case CC_SPACE: {
+      testcase( z[0]==' ' );
+      testcase( z[0]=='\t' );
+      testcase( z[0]=='\n' );
+      testcase( z[0]=='\f' );
+      testcase( z[0]=='\r' );
+      for(i=1; sqlite3Isspace(z[i]); i++){}
+      *tokenType = TK_SPACE;
+      return i;
+    }
+    case CC_MINUS: {
+      if( z[1]=='-' ){
+        for(i=2; (c=z[i])!=0 && c!='\n'; i++){}
+        *tokenType = TK_SPACE;   /* IMP: R-22934-25134 */
+        return i;
+      }
+      *tokenType = TK_MINUS;
+      return 1;
+    }
+    case CC_LP: {
+      *tokenType = TK_LP;
+      return 1;
+    }
+    case CC_RP: {
+      *tokenType = TK_RP;
+      return 1;
+    }
+    case CC_SEMI: {
+      *tokenType = TK_SEMI;
+      return 1;
+    }
+    case CC_PLUS: {
+      *tokenType = TK_PLUS;
+      return 1;
+    }
+    case CC_STAR: {
+      *tokenType = TK_STAR;
+      return 1;
+    }
+    case CC_SLASH: {
+      if( z[1]!='*' || z[2]==0 ){
+        *tokenType = TK_SLASH;
+        return 1;
+      }
+      for(i=3, c=z[2]; (c!='*' || z[i]!='/') && (c=z[i])!=0; i++){}
+      if( c ) i++;
+      *tokenType = TK_SPACE;   /* IMP: R-22934-25134 */
+      return i;
+    }
+    case CC_PERCENT: {
+      *tokenType = TK_REM;
+      return 1;
+    }
+    case CC_EQ: {
+      *tokenType = TK_EQ;
+      return 1 + (z[1]=='=');
+    }
+    case CC_LT: {
+      if( (c=z[1])=='=' ){
+        *tokenType = TK_LE;
+        return 2;
+      }else if( c=='>' ){
+        *tokenType = TK_NE;
+        return 2;
+      }else if( c=='<' ){
+        *tokenType = TK_LSHIFT;
+        return 2;
+      }else{
+        *tokenType = TK_LT;
+        return 1;
+      }
+    }
+    case CC_GT: {
+      if( (c=z[1])=='=' ){
+        *tokenType = TK_GE;
+        return 2;
+      }else if( c=='>' ){
+        *tokenType = TK_RSHIFT;
+        return 2;
+      }else{
+        *tokenType = TK_GT;
+        return 1;
+      }
+    }
+    case CC_BANG: {
+      if( z[1]!='=' ){
+        *tokenType = TK_ILLEGAL;
+        return 1;
+      }else{
+        *tokenType = TK_NE;
+        return 2;
+      }
+    }
+    case CC_PIPE: {
+      if( z[1]!='|' ){
+        *tokenType = TK_BITOR;
+        return 1;
+      }else{
+        *tokenType = TK_CONCAT;
+        return 2;
+      }
+    }
+    case CC_COMMA: {
+      *tokenType = TK_COMMA;
+      return 1;
+    }
+    case CC_AND: {
+      *tokenType = TK_BITAND;
+      return 1;
+    }
+    case CC_TILDA: {
+      *tokenType = TK_BITNOT;
+      return 1;
+    }
+    case CC_QUOTE: {
+      int delim = z[0];
+      testcase( delim=='`' );
+      testcase( delim=='\'' );
+      testcase( delim=='"' );
+      for(i=1; (c=z[i])!=0; i++){
+        if( c==delim ){
+          if( z[i+1]==delim ){
+            i++;
+          }else{
+            break;
+          }
+        }
+      }
+      if( c=='\'' ){
+        *tokenType = TK_STRING;
+        return i+1;
+      }else if( c!=0 ){
+        *tokenType = TK_ID;
+        return i+1;
+      }else{
+        *tokenType = TK_ILLEGAL;
+        return i;
+      }
+    }
+    case CC_DOT: {
+#ifndef SQLITE_OMIT_FLOATING_POINT
+      if( !sqlite3Isdigit(z[1]) )
+#endif
+      {
+        *tokenType = TK_DOT;
+        return 1;
+      }
+      /* If the next character is a digit, this is a floating point
+      ** number that begins with ".".  Fall thru into the next case */
+    }
+    case CC_DIGIT: {
+      testcase( z[0]=='0' );  testcase( z[0]=='1' );  testcase( z[0]=='2' );
+      testcase( z[0]=='3' );  testcase( z[0]=='4' );  testcase( z[0]=='5' );
+      testcase( z[0]=='6' );  testcase( z[0]=='7' );  testcase( z[0]=='8' );
+      testcase( z[0]=='9' );
+      *tokenType = TK_INTEGER;
+#ifndef SQLITE_OMIT_HEX_INTEGER
+      if( z[0]=='0' && (z[1]=='x' || z[1]=='X') && sqlite3Isxdigit(z[2]) ){
+        for(i=3; sqlite3Isxdigit(z[i]); i++){}
+        return i;
+      }
+#endif
+      for(i=0; sqlite3Isdigit(z[i]); i++){}
+#ifndef SQLITE_OMIT_FLOATING_POINT
+      if( z[i]=='.' ){
+        i++;
+        while( sqlite3Isdigit(z[i]) ){ i++; }
+        *tokenType = TK_FLOAT;
+      }
+      if( (z[i]=='e' || z[i]=='E') &&
+           ( sqlite3Isdigit(z[i+1]) 
+            || ((z[i+1]=='+' || z[i+1]=='-') && sqlite3Isdigit(z[i+2]))
+           )
+      ){
+        i += 2;
+        while( sqlite3Isdigit(z[i]) ){ i++; }
+        *tokenType = TK_FLOAT;
+      }
+#endif
+      while( IdChar(z[i]) ){
+        *tokenType = TK_ILLEGAL;
+        i++;
+      }
+      return i;
+    }
+    case CC_QUOTE2: {
+      for(i=1, c=z[0]; c!=']' && (c=z[i])!=0; i++){}
+      *tokenType = c==']' ? TK_ID : TK_ILLEGAL;
+      return i;
+    }
+    case CC_VARNUM: {
+      *tokenType = TK_VARIABLE;
+      for(i=1; sqlite3Isdigit(z[i]); i++){}
+      return i;
+    }
+    case CC_DOLLAR:
+    case CC_VARALPHA: {
+      int n = 0;
+      testcase( z[0]=='$' );  testcase( z[0]=='@' );
+      testcase( z[0]==':' );  testcase( z[0]=='#' );
+      *tokenType = TK_VARIABLE;
+      for(i=1; (c=z[i])!=0; i++){
+        if( IdChar(c) ){
+          n++;
+#ifndef SQLITE_OMIT_TCL_VARIABLE
+        }else if( c=='(' && n>0 ){
+          do{
+            i++;
+          }while( (c=z[i])!=0 && !sqlite3Isspace(c) && c!=')' );
+          if( c==')' ){
+            i++;
+          }else{
+            *tokenType = TK_ILLEGAL;
+          }
+          break;
+        }else if( c==':' && z[i+1]==':' ){
+          i++;
+#endif
+        }else{
+          break;
+        }
+      }
+      if( n==0 ) *tokenType = TK_ILLEGAL;
+      return i;
+    }
+    case CC_KYWD: {
+      for(i=1; aiClass[z[i]]<=CC_KYWD; i++){}
+      if( IdChar(z[i]) ){
+        /* This token started out using characters that can appear in keywords,
+        ** but z[i] is a character not allowed within keywords, so this must
+        ** be an identifier instead */
+        i++;
+        break;
+      }
+      *tokenType = TK_ID;
+      return keywordCode((char*)z, i, tokenType);
+    }
+    case CC_X: {
+#ifndef SQLITE_OMIT_BLOB_LITERAL
+      testcase( z[0]=='x' ); testcase( z[0]=='X' );
+      if( z[1]=='\'' ){
+        *tokenType = TK_BLOB;
+        for(i=2; sqlite3Isxdigit(z[i]); i++){}
+        if( z[i]!='\'' || i%2 ){
+          *tokenType = TK_ILLEGAL;
+          while( z[i] && z[i]!='\'' ){ i++; }
+        }
+        if( z[i] ) i++;
+        return i;
+      }
+#endif
+      /* If it is not a BLOB literal, then it must be an ID, since no
+      ** SQL keywords start with the letter 'x'.  Fall through */
+    }
+    case CC_ID: {
+      i = 1;
+      break;
+    }
+    default: {
+      *tokenType = TK_ILLEGAL;
+      return 1;
+    }
+  }
+  while( IdChar(z[i]) ){ i++; }
+  *tokenType = TK_ID;
+  return i;
+}
+
+/*
+** Run the parser on the given SQL string.  The parser structure is
+** passed in.  An SQLITE_ status code is returned.  If an error occurs
+** then an and attempt is made to write an error message into 
+** memory obtained from sqlite3_malloc() and to make *pzErrMsg point to that
+** error message.
+*/
+SQLITE_PRIVATE int sqlite3RunParser(Parse *pParse, const char *zSql, char **pzErrMsg){
+  int nErr = 0;                   /* Number of errors encountered */
+  int i;                          /* Loop counter */
+  void *pEngine;                  /* The LEMON-generated LALR(1) parser */
+  int tokenType;                  /* type of the next token */
+  int lastTokenParsed = -1;       /* type of the previous token */
+  sqlite3 *db = pParse->db;       /* The database connection */
+  int mxSqlLen;                   /* Max length of an SQL string */
+
+  assert( zSql!=0 );
+  mxSqlLen = db->aLimit[SQLITE_LIMIT_SQL_LENGTH];
+  if( db->nVdbeActive==0 ){
+    db->u1.isInterrupted = 0;
+  }
+  pParse->rc = SQLITE_OK;
+  pParse->zTail = zSql;
+  i = 0;
+  assert( pzErrMsg!=0 );
+  /* sqlite3ParserTrace(stdout, "parser: "); */
+  pEngine = sqlite3ParserAlloc(sqlite3Malloc);
+  if( pEngine==0 ){
+    sqlite3OomFault(db);
+    return SQLITE_NOMEM_BKPT;
+  }
+  assert( pParse->pNewTable==0 );
+  assert( pParse->pNewTrigger==0 );
+  assert( pParse->nVar==0 );
+  assert( pParse->nzVar==0 );
+  assert( pParse->azVar==0 );
+  while( 1 ){
+    assert( i>=0 );
+    if( zSql[i]!=0 ){
+      pParse->sLastToken.z = &zSql[i];
+      pParse->sLastToken.n = sqlite3GetToken((u8*)&zSql[i],&tokenType);
+      i += pParse->sLastToken.n;
+      if( i>mxSqlLen ){
+        pParse->rc = SQLITE_TOOBIG;
+        break;
+      }
+    }else{
+      /* Upon reaching the end of input, call the parser two more times
+      ** with tokens TK_SEMI and 0, in that order. */
+      if( lastTokenParsed==TK_SEMI ){
+        tokenType = 0;
+      }else if( lastTokenParsed==0 ){
+        break;
+      }else{
+        tokenType = TK_SEMI;
+      }
+    }
+    if( tokenType>=TK_SPACE ){
+      assert( tokenType==TK_SPACE || tokenType==TK_ILLEGAL );
+      if( db->u1.isInterrupted ){
+        pParse->rc = SQLITE_INTERRUPT;
+        break;
+      }
+      if( tokenType==TK_ILLEGAL ){
+        sqlite3ErrorMsg(pParse, "unrecognized token: \"%T\"",
+                        &pParse->sLastToken);
+        break;
+      }
+    }else{
+      sqlite3Parser(pEngine, tokenType, pParse->sLastToken, pParse);
+      lastTokenParsed = tokenType;
+      if( pParse->rc!=SQLITE_OK || db->mallocFailed ) break;
+    }
+  }
+  assert( nErr==0 );
+  pParse->zTail = &zSql[i];
+#ifdef YYTRACKMAXSTACKDEPTH
+  sqlite3_mutex_enter(sqlite3MallocMutex());
+  sqlite3StatusHighwater(SQLITE_STATUS_PARSER_STACK,
+      sqlite3ParserStackPeak(pEngine)
+  );
+  sqlite3_mutex_leave(sqlite3MallocMutex());
+#endif /* YYDEBUG */
+  sqlite3ParserFree(pEngine, sqlite3_free);
+  if( db->mallocFailed ){
+    pParse->rc = SQLITE_NOMEM_BKPT;
+  }
+  if( pParse->rc!=SQLITE_OK && pParse->rc!=SQLITE_DONE && pParse->zErrMsg==0 ){
+    pParse->zErrMsg = sqlite3MPrintf(db, "%s", sqlite3ErrStr(pParse->rc));
+  }
+  assert( pzErrMsg!=0 );
+  if( pParse->zErrMsg ){
+    *pzErrMsg = pParse->zErrMsg;
+    sqlite3_log(pParse->rc, "%s", *pzErrMsg);
+    pParse->zErrMsg = 0;
+    nErr++;
+  }
+  if( pParse->pVdbe && pParse->nErr>0 && pParse->nested==0 ){
+    sqlite3VdbeDelete(pParse->pVdbe);
+    pParse->pVdbe = 0;
+  }
+#ifndef SQLITE_OMIT_SHARED_CACHE
+  if( pParse->nested==0 ){
+    sqlite3DbFree(db, pParse->aTableLock);
+    pParse->aTableLock = 0;
+    pParse->nTableLock = 0;
+  }
+#endif
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  sqlite3_free(pParse->apVtabLock);
+#endif
+
+  if( !IN_DECLARE_VTAB ){
+    /* If the pParse->declareVtab flag is set, do not delete any table 
+    ** structure built up in pParse->pNewTable. The calling code (see vtab.c)
+    ** will take responsibility for freeing the Table structure.
+    */
+    sqlite3DeleteTable(db, pParse->pNewTable);
+  }
+
+  if( pParse->pWithToFree ) sqlite3WithDelete(db, pParse->pWithToFree);
+  sqlite3DeleteTrigger(db, pParse->pNewTrigger);
+  for(i=pParse->nzVar-1; i>=0; i--) sqlite3DbFree(db, pParse->azVar[i]);
+  sqlite3DbFree(db, pParse->azVar);
+  while( pParse->pAinc ){
+    AutoincInfo *p = pParse->pAinc;
+    pParse->pAinc = p->pNext;
+    sqlite3DbFree(db, p);
+  }
+  while( pParse->pZombieTab ){
+    Table *p = pParse->pZombieTab;
+    pParse->pZombieTab = p->pNextZombie;
+    sqlite3DeleteTable(db, p);
+  }
+  assert( nErr==0 || pParse->rc!=SQLITE_OK );
+  return nErr;
+}
+
+/************** End of tokenize.c ********************************************/
+/************** Begin file complete.c ****************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** An tokenizer for SQL
+**
+** This file contains C code that implements the sqlite3_complete() API.
+** This code used to be part of the tokenizer.c source file.  But by
+** separating it out, the code will be automatically omitted from
+** static links that do not use it.
+*/
+/* #include "sqliteInt.h" */
+#ifndef SQLITE_OMIT_COMPLETE
+
+/*
+** This is defined in tokenize.c.  We just have to import the definition.
+*/
+#ifndef SQLITE_AMALGAMATION
+#ifdef SQLITE_ASCII
+#define IdChar(C)  ((sqlite3CtypeMap[(unsigned char)C]&0x46)!=0)
+#endif
+#ifdef SQLITE_EBCDIC
+SQLITE_PRIVATE const char sqlite3IsEbcdicIdChar[];
+#define IdChar(C)  (((c=C)>=0x42 && sqlite3IsEbcdicIdChar[c-0x40]))
+#endif
+#endif /* SQLITE_AMALGAMATION */
+
+
+/*
+** Token types used by the sqlite3_complete() routine.  See the header
+** comments on that procedure for additional information.
+*/
+#define tkSEMI    0
+#define tkWS      1
+#define tkOTHER   2
+#ifndef SQLITE_OMIT_TRIGGER
+#define tkEXPLAIN 3
+#define tkCREATE  4
+#define tkTEMP    5
+#define tkTRIGGER 6
+#define tkEND     7
+#endif
+
+/*
+** Return TRUE if the given SQL string ends in a semicolon.
+**
+** Special handling is require for CREATE TRIGGER statements.
+** Whenever the CREATE TRIGGER keywords are seen, the statement
+** must end with ";END;".
+**
+** This implementation uses a state machine with 8 states:
+**
+**   (0) INVALID   We have not yet seen a non-whitespace character.
+**
+**   (1) START     At the beginning or end of an SQL statement.  This routine
+**                 returns 1 if it ends in the START state and 0 if it ends
+**                 in any other state.
+**
+**   (2) NORMAL    We are in the middle of statement which ends with a single
+**                 semicolon.
+**
+**   (3) EXPLAIN   The keyword EXPLAIN has been seen at the beginning of 
+**                 a statement.
+**
+**   (4) CREATE    The keyword CREATE has been seen at the beginning of a
+**                 statement, possibly preceded by EXPLAIN and/or followed by
+**                 TEMP or TEMPORARY
+**
+**   (5) TRIGGER   We are in the middle of a trigger definition that must be
+**                 ended by a semicolon, the keyword END, and another semicolon.
+**
+**   (6) SEMI      We've seen the first semicolon in the ";END;" that occurs at
+**                 the end of a trigger definition.
+**
+**   (7) END       We've seen the ";END" of the ";END;" that occurs at the end
+**                 of a trigger definition.
+**
+** Transitions between states above are determined by tokens extracted
+** from the input.  The following tokens are significant:
+**
+**   (0) tkSEMI      A semicolon.
+**   (1) tkWS        Whitespace.
+**   (2) tkOTHER     Any other SQL token.
+**   (3) tkEXPLAIN   The "explain" keyword.
+**   (4) tkCREATE    The "create" keyword.
+**   (5) tkTEMP      The "temp" or "temporary" keyword.
+**   (6) tkTRIGGER   The "trigger" keyword.
+**   (7) tkEND       The "end" keyword.
+**
+** Whitespace never causes a state transition and is always ignored.
+** This means that a SQL string of all whitespace is invalid.
+**
+** If we compile with SQLITE_OMIT_TRIGGER, all of the computation needed
+** to recognize the end of a trigger can be omitted.  All we have to do
+** is look for a semicolon that is not part of an string or comment.
+*/
+SQLITE_API int sqlite3_complete(const char *zSql){
+  u8 state = 0;   /* Current state, using numbers defined in header comment */
+  u8 token;       /* Value of the next token */
+
+#ifndef SQLITE_OMIT_TRIGGER
+  /* A complex statement machine used to detect the end of a CREATE TRIGGER
+  ** statement.  This is the normal case.
+  */
+  static const u8 trans[8][8] = {
+                     /* Token:                                                */
+     /* State:       **  SEMI  WS  OTHER  EXPLAIN  CREATE  TEMP  TRIGGER  END */
+     /* 0 INVALID: */ {    1,  0,     2,       3,      4,    2,       2,   2, },
+     /* 1   START: */ {    1,  1,     2,       3,      4,    2,       2,   2, },
+     /* 2  NORMAL: */ {    1,  2,     2,       2,      2,    2,       2,   2, },
+     /* 3 EXPLAIN: */ {    1,  3,     3,       2,      4,    2,       2,   2, },
+     /* 4  CREATE: */ {    1,  4,     2,       2,      2,    4,       5,   2, },
+     /* 5 TRIGGER: */ {    6,  5,     5,       5,      5,    5,       5,   5, },
+     /* 6    SEMI: */ {    6,  6,     5,       5,      5,    5,       5,   7, },
+     /* 7     END: */ {    1,  7,     5,       5,      5,    5,       5,   5, },
+  };
+#else
+  /* If triggers are not supported by this compile then the statement machine
+  ** used to detect the end of a statement is much simpler
+  */
+  static const u8 trans[3][3] = {
+                     /* Token:           */
+     /* State:       **  SEMI  WS  OTHER */
+     /* 0 INVALID: */ {    1,  0,     2, },
+     /* 1   START: */ {    1,  1,     2, },
+     /* 2  NORMAL: */ {    1,  2,     2, },
+  };
+#endif /* SQLITE_OMIT_TRIGGER */
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( zSql==0 ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+
+  while( *zSql ){
+    switch( *zSql ){
+      case ';': {  /* A semicolon */
+        token = tkSEMI;
+        break;
+      }
+      case ' ':
+      case '\r':
+      case '\t':
+      case '\n':
+      case '\f': {  /* White space is ignored */
+        token = tkWS;
+        break;
+      }
+      case '/': {   /* C-style comments */
+        if( zSql[1]!='*' ){
+          token = tkOTHER;
+          break;
+        }
+        zSql += 2;
+        while( zSql[0] && (zSql[0]!='*' || zSql[1]!='/') ){ zSql++; }
+        if( zSql[0]==0 ) return 0;
+        zSql++;
+        token = tkWS;
+        break;
+      }
+      case '-': {   /* SQL-style comments from "--" to end of line */
+        if( zSql[1]!='-' ){
+          token = tkOTHER;
+          break;
+        }
+        while( *zSql && *zSql!='\n' ){ zSql++; }
+        if( *zSql==0 ) return state==1;
+        token = tkWS;
+        break;
+      }
+      case '[': {   /* Microsoft-style identifiers in [...] */
+        zSql++;
+        while( *zSql && *zSql!=']' ){ zSql++; }
+        if( *zSql==0 ) return 0;
+        token = tkOTHER;
+        break;
+      }
+      case '`':     /* Grave-accent quoted symbols used by MySQL */
+      case '"':     /* single- and double-quoted strings */
+      case '\'': {
+        int c = *zSql;
+        zSql++;
+        while( *zSql && *zSql!=c ){ zSql++; }
+        if( *zSql==0 ) return 0;
+        token = tkOTHER;
+        break;
+      }
+      default: {
+#ifdef SQLITE_EBCDIC
+        unsigned char c;
+#endif
+        if( IdChar((u8)*zSql) ){
+          /* Keywords and unquoted identifiers */
+          int nId;
+          for(nId=1; IdChar(zSql[nId]); nId++){}
+#ifdef SQLITE_OMIT_TRIGGER
+          token = tkOTHER;
+#else
+          switch( *zSql ){
+            case 'c': case 'C': {
+              if( nId==6 && sqlite3StrNICmp(zSql, "create", 6)==0 ){
+                token = tkCREATE;
+              }else{
+                token = tkOTHER;
+              }
+              break;
+            }
+            case 't': case 'T': {
+              if( nId==7 && sqlite3StrNICmp(zSql, "trigger", 7)==0 ){
+                token = tkTRIGGER;
+              }else if( nId==4 && sqlite3StrNICmp(zSql, "temp", 4)==0 ){
+                token = tkTEMP;
+              }else if( nId==9 && sqlite3StrNICmp(zSql, "temporary", 9)==0 ){
+                token = tkTEMP;
+              }else{
+                token = tkOTHER;
+              }
+              break;
+            }
+            case 'e':  case 'E': {
+              if( nId==3 && sqlite3StrNICmp(zSql, "end", 3)==0 ){
+                token = tkEND;
+              }else
+#ifndef SQLITE_OMIT_EXPLAIN
+              if( nId==7 && sqlite3StrNICmp(zSql, "explain", 7)==0 ){
+                token = tkEXPLAIN;
+              }else
+#endif
+              {
+                token = tkOTHER;
+              }
+              break;
+            }
+            default: {
+              token = tkOTHER;
+              break;
+            }
+          }
+#endif /* SQLITE_OMIT_TRIGGER */
+          zSql += nId-1;
+        }else{
+          /* Operators and special symbols */
+          token = tkOTHER;
+        }
+        break;
+      }
+    }
+    state = trans[state][token];
+    zSql++;
+  }
+  return state==1;
+}
+
+#ifndef SQLITE_OMIT_UTF16
+/*
+** This routine is the same as the sqlite3_complete() routine described
+** above, except that the parameter is required to be UTF-16 encoded, not
+** UTF-8.
+*/
+SQLITE_API int sqlite3_complete16(const void *zSql){
+  sqlite3_value *pVal;
+  char const *zSql8;
+  int rc;
+
+#ifndef SQLITE_OMIT_AUTOINIT
+  rc = sqlite3_initialize();
+  if( rc ) return rc;
+#endif
+  pVal = sqlite3ValueNew(0);
+  sqlite3ValueSetStr(pVal, -1, zSql, SQLITE_UTF16NATIVE, SQLITE_STATIC);
+  zSql8 = sqlite3ValueText(pVal, SQLITE_UTF8);
+  if( zSql8 ){
+    rc = sqlite3_complete(zSql8);
+  }else{
+    rc = SQLITE_NOMEM_BKPT;
+  }
+  sqlite3ValueFree(pVal);
+  return rc & 0xff;
+}
+#endif /* SQLITE_OMIT_UTF16 */
+#endif /* SQLITE_OMIT_COMPLETE */
+
+/************** End of complete.c ********************************************/
+/************** Begin file main.c ********************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** Main file for the SQLite library.  The routines in this file
+** implement the programmer interface to the library.  Routines in
+** other files are for internal use by SQLite and should not be
+** accessed by users of the library.
+*/
+/* #include "sqliteInt.h" */
+
+#ifdef SQLITE_ENABLE_FTS3
+/************** Include fts3.h in the middle of main.c ***********************/
+/************** Begin file fts3.h ********************************************/
+/*
+** 2006 Oct 10
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This header file is used by programs that want to link against the
+** FTS3 library.  All it does is declare the sqlite3Fts3Init() interface.
+*/
+/* #include "sqlite3.h" */
+
+#if 0
+extern "C" {
+#endif  /* __cplusplus */
+
+SQLITE_PRIVATE int sqlite3Fts3Init(sqlite3 *db);
+
+#if 0
+}  /* extern "C" */
+#endif  /* __cplusplus */
+
+/************** End of fts3.h ************************************************/
+/************** Continuing where we left off in main.c ***********************/
+#endif
+#ifdef SQLITE_ENABLE_RTREE
+/************** Include rtree.h in the middle of main.c **********************/
+/************** Begin file rtree.h *******************************************/
+/*
+** 2008 May 26
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This header file is used by programs that want to link against the
+** RTREE library.  All it does is declare the sqlite3RtreeInit() interface.
+*/
+/* #include "sqlite3.h" */
+
+#if 0
+extern "C" {
+#endif  /* __cplusplus */
+
+SQLITE_PRIVATE int sqlite3RtreeInit(sqlite3 *db);
+
+#if 0
+}  /* extern "C" */
+#endif  /* __cplusplus */
+
+/************** End of rtree.h ***********************************************/
+/************** Continuing where we left off in main.c ***********************/
+#endif
+#ifdef SQLITE_ENABLE_ICU
+/************** Include sqliteicu.h in the middle of main.c ******************/
+/************** Begin file sqliteicu.h ***************************************/
+/*
+** 2008 May 26
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This header file is used by programs that want to link against the
+** ICU extension.  All it does is declare the sqlite3IcuInit() interface.
+*/
+/* #include "sqlite3.h" */
+
+#if 0
+extern "C" {
+#endif  /* __cplusplus */
+
+SQLITE_PRIVATE int sqlite3IcuInit(sqlite3 *db);
+
+#if 0
+}  /* extern "C" */
+#endif  /* __cplusplus */
+
+
+/************** End of sqliteicu.h *******************************************/
+/************** Continuing where we left off in main.c ***********************/
+#endif
+#ifdef SQLITE_ENABLE_JSON1
+SQLITE_PRIVATE int sqlite3Json1Init(sqlite3*);
+#endif
+#ifdef SQLITE_ENABLE_FTS5
+SQLITE_PRIVATE int sqlite3Fts5Init(sqlite3*);
+#endif
+
+#ifndef SQLITE_AMALGAMATION
+/* IMPLEMENTATION-OF: R-46656-45156 The sqlite3_version[] string constant
+** contains the text of SQLITE_VERSION macro. 
+*/
+SQLITE_API const char sqlite3_version[] = SQLITE_VERSION;
+#endif
+
+/* IMPLEMENTATION-OF: R-53536-42575 The sqlite3_libversion() function returns
+** a pointer to the to the sqlite3_version[] string constant. 
+*/
+SQLITE_API const char *sqlite3_libversion(void){ return sqlite3_version; }
+
+/* IMPLEMENTATION-OF: R-63124-39300 The sqlite3_sourceid() function returns a
+** pointer to a string constant whose value is the same as the
+** SQLITE_SOURCE_ID C preprocessor macro. 
+*/
+SQLITE_API const char *sqlite3_sourceid(void){ return SQLITE_SOURCE_ID; }
+
+/* IMPLEMENTATION-OF: R-35210-63508 The sqlite3_libversion_number() function
+** returns an integer equal to SQLITE_VERSION_NUMBER.
+*/
+SQLITE_API int sqlite3_libversion_number(void){ return SQLITE_VERSION_NUMBER; }
+
+/* IMPLEMENTATION-OF: R-20790-14025 The sqlite3_threadsafe() function returns
+** zero if and only if SQLite was compiled with mutexing code omitted due to
+** the SQLITE_THREADSAFE compile-time option being set to 0.
+*/
+SQLITE_API int sqlite3_threadsafe(void){ return SQLITE_THREADSAFE; }
+
+/*
+** When compiling the test fixture or with debugging enabled (on Win32),
+** this variable being set to non-zero will cause OSTRACE macros to emit
+** extra diagnostic information.
+*/
+#ifdef SQLITE_HAVE_OS_TRACE
+# ifndef SQLITE_DEBUG_OS_TRACE
+#   define SQLITE_DEBUG_OS_TRACE 0
+# endif
+  int sqlite3OSTrace = SQLITE_DEBUG_OS_TRACE;
+#endif
+
+#if !defined(SQLITE_OMIT_TRACE) && defined(SQLITE_ENABLE_IOTRACE)
+/*
+** If the following function pointer is not NULL and if
+** SQLITE_ENABLE_IOTRACE is enabled, then messages describing
+** I/O active are written using this function.  These messages
+** are intended for debugging activity only.
+*/
+SQLITE_API void (SQLITE_CDECL *sqlite3IoTrace)(const char*, ...) = 0;
+#endif
+
+/*
+** If the following global variable points to a string which is the
+** name of a directory, then that directory will be used to store
+** temporary files.
+**
+** See also the "PRAGMA temp_store_directory" SQL command.
+*/
+SQLITE_API char *sqlite3_temp_directory = 0;
+
+/*
+** If the following global variable points to a string which is the
+** name of a directory, then that directory will be used to store
+** all database files specified with a relative pathname.
+**
+** See also the "PRAGMA data_store_directory" SQL command.
+*/
+SQLITE_API char *sqlite3_data_directory = 0;
+
+/*
+** Initialize SQLite.  
+**
+** This routine must be called to initialize the memory allocation,
+** VFS, and mutex subsystems prior to doing any serious work with
+** SQLite.  But as long as you do not compile with SQLITE_OMIT_AUTOINIT
+** this routine will be called automatically by key routines such as
+** sqlite3_open().  
+**
+** This routine is a no-op except on its very first call for the process,
+** or for the first call after a call to sqlite3_shutdown.
+**
+** The first thread to call this routine runs the initialization to
+** completion.  If subsequent threads call this routine before the first
+** thread has finished the initialization process, then the subsequent
+** threads must block until the first thread finishes with the initialization.
+**
+** The first thread might call this routine recursively.  Recursive
+** calls to this routine should not block, of course.  Otherwise the
+** initialization process would never complete.
+**
+** Let X be the first thread to enter this routine.  Let Y be some other
+** thread.  Then while the initial invocation of this routine by X is
+** incomplete, it is required that:
+**
+**    *  Calls to this routine from Y must block until the outer-most
+**       call by X completes.
+**
+**    *  Recursive calls to this routine from thread X return immediately
+**       without blocking.
+*/
+SQLITE_API int sqlite3_initialize(void){
+  MUTEX_LOGIC( sqlite3_mutex *pMaster; )       /* The main static mutex */
+  int rc;                                      /* Result code */
+#ifdef SQLITE_EXTRA_INIT
+  int bRunExtraInit = 0;                       /* Extra initialization needed */
+#endif
+
+#ifdef SQLITE_OMIT_WSD
+  rc = sqlite3_wsd_init(4096, 24);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+#endif
+
+  /* If the following assert() fails on some obscure processor/compiler
+  ** combination, the work-around is to set the correct pointer
+  ** size at compile-time using -DSQLITE_PTRSIZE=n compile-time option */
+  assert( SQLITE_PTRSIZE==sizeof(char*) );
+
+  /* If SQLite is already completely initialized, then this call
+  ** to sqlite3_initialize() should be a no-op.  But the initialization
+  ** must be complete.  So isInit must not be set until the very end
+  ** of this routine.
+  */
+  if( sqlite3GlobalConfig.isInit ) return SQLITE_OK;
+
+  /* Make sure the mutex subsystem is initialized.  If unable to 
+  ** initialize the mutex subsystem, return early with the error.
+  ** If the system is so sick that we are unable to allocate a mutex,
+  ** there is not much SQLite is going to be able to do.
+  **
+  ** The mutex subsystem must take care of serializing its own
+  ** initialization.
+  */
+  rc = sqlite3MutexInit();
+  if( rc ) return rc;
+
+  /* Initialize the malloc() system and the recursive pInitMutex mutex.
+  ** This operation is protected by the STATIC_MASTER mutex.  Note that
+  ** MutexAlloc() is called for a static mutex prior to initializing the
+  ** malloc subsystem - this implies that the allocation of a static
+  ** mutex must not require support from the malloc subsystem.
+  */
+  MUTEX_LOGIC( pMaster = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); )
+  sqlite3_mutex_enter(pMaster);
+  sqlite3GlobalConfig.isMutexInit = 1;
+  if( !sqlite3GlobalConfig.isMallocInit ){
+    rc = sqlite3MallocInit();
+  }
+  if( rc==SQLITE_OK ){
+    sqlite3GlobalConfig.isMallocInit = 1;
+    if( !sqlite3GlobalConfig.pInitMutex ){
+      sqlite3GlobalConfig.pInitMutex =
+           sqlite3MutexAlloc(SQLITE_MUTEX_RECURSIVE);
+      if( sqlite3GlobalConfig.bCoreMutex && !sqlite3GlobalConfig.pInitMutex ){
+        rc = SQLITE_NOMEM_BKPT;
+      }
+    }
+  }
+  if( rc==SQLITE_OK ){
+    sqlite3GlobalConfig.nRefInitMutex++;
+  }
+  sqlite3_mutex_leave(pMaster);
+
+  /* If rc is not SQLITE_OK at this point, then either the malloc
+  ** subsystem could not be initialized or the system failed to allocate
+  ** the pInitMutex mutex. Return an error in either case.  */
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+
+  /* Do the rest of the initialization under the recursive mutex so
+  ** that we will be able to handle recursive calls into
+  ** sqlite3_initialize().  The recursive calls normally come through
+  ** sqlite3_os_init() when it invokes sqlite3_vfs_register(), but other
+  ** recursive calls might also be possible.
+  **
+  ** IMPLEMENTATION-OF: R-00140-37445 SQLite automatically serializes calls
+  ** to the xInit method, so the xInit method need not be threadsafe.
+  **
+  ** The following mutex is what serializes access to the appdef pcache xInit
+  ** methods.  The sqlite3_pcache_methods.xInit() all is embedded in the
+  ** call to sqlite3PcacheInitialize().
+  */
+  sqlite3_mutex_enter(sqlite3GlobalConfig.pInitMutex);
+  if( sqlite3GlobalConfig.isInit==0 && sqlite3GlobalConfig.inProgress==0 ){
+    sqlite3GlobalConfig.inProgress = 1;
+#ifdef SQLITE_ENABLE_SQLLOG
+    {
+      extern void sqlite3_init_sqllog(void);
+      sqlite3_init_sqllog();
+    }
+#endif
+    memset(&sqlite3BuiltinFunctions, 0, sizeof(sqlite3BuiltinFunctions));
+    sqlite3RegisterBuiltinFunctions();
+    if( sqlite3GlobalConfig.isPCacheInit==0 ){
+      rc = sqlite3PcacheInitialize();
+    }
+    if( rc==SQLITE_OK ){
+      sqlite3GlobalConfig.isPCacheInit = 1;
+      rc = sqlite3OsInit();
+    }
+    if( rc==SQLITE_OK ){
+      sqlite3PCacheBufferSetup( sqlite3GlobalConfig.pPage, 
+          sqlite3GlobalConfig.szPage, sqlite3GlobalConfig.nPage);
+      sqlite3GlobalConfig.isInit = 1;
+#ifdef SQLITE_EXTRA_INIT
+      bRunExtraInit = 1;
+#endif
+    }
+    sqlite3GlobalConfig.inProgress = 0;
+  }
+  sqlite3_mutex_leave(sqlite3GlobalConfig.pInitMutex);
+
+  /* Go back under the static mutex and clean up the recursive
+  ** mutex to prevent a resource leak.
+  */
+  sqlite3_mutex_enter(pMaster);
+  sqlite3GlobalConfig.nRefInitMutex--;
+  if( sqlite3GlobalConfig.nRefInitMutex<=0 ){
+    assert( sqlite3GlobalConfig.nRefInitMutex==0 );
+    sqlite3_mutex_free(sqlite3GlobalConfig.pInitMutex);
+    sqlite3GlobalConfig.pInitMutex = 0;
+  }
+  sqlite3_mutex_leave(pMaster);
+
+  /* The following is just a sanity check to make sure SQLite has
+  ** been compiled correctly.  It is important to run this code, but
+  ** we don't want to run it too often and soak up CPU cycles for no
+  ** reason.  So we run it once during initialization.
+  */
+#ifndef NDEBUG
+#ifndef SQLITE_OMIT_FLOATING_POINT
+  /* This section of code's only "output" is via assert() statements. */
+  if ( rc==SQLITE_OK ){
+    u64 x = (((u64)1)<<63)-1;
+    double y;
+    assert(sizeof(x)==8);
+    assert(sizeof(x)==sizeof(y));
+    memcpy(&y, &x, 8);
+    assert( sqlite3IsNaN(y) );
+  }
+#endif
+#endif
+
+  /* Do extra initialization steps requested by the SQLITE_EXTRA_INIT
+  ** compile-time option.
+  */
+#ifdef SQLITE_EXTRA_INIT
+  if( bRunExtraInit ){
+    int SQLITE_EXTRA_INIT(const char*);
+    rc = SQLITE_EXTRA_INIT(0);
+  }
+#endif
+
+  return rc;
+}
+
+/*
+** Undo the effects of sqlite3_initialize().  Must not be called while
+** there are outstanding database connections or memory allocations or
+** while any part of SQLite is otherwise in use in any thread.  This
+** routine is not threadsafe.  But it is safe to invoke this routine
+** on when SQLite is already shut down.  If SQLite is already shut down
+** when this routine is invoked, then this routine is a harmless no-op.
+*/
+SQLITE_API int sqlite3_shutdown(void){
+#ifdef SQLITE_OMIT_WSD
+  int rc = sqlite3_wsd_init(4096, 24);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+#endif
+
+  if( sqlite3GlobalConfig.isInit ){
+#ifdef SQLITE_EXTRA_SHUTDOWN
+    void SQLITE_EXTRA_SHUTDOWN(void);
+    SQLITE_EXTRA_SHUTDOWN();
+#endif
+    sqlite3_os_end();
+    sqlite3_reset_auto_extension();
+    sqlite3GlobalConfig.isInit = 0;
+  }
+  if( sqlite3GlobalConfig.isPCacheInit ){
+    sqlite3PcacheShutdown();
+    sqlite3GlobalConfig.isPCacheInit = 0;
+  }
+  if( sqlite3GlobalConfig.isMallocInit ){
+    sqlite3MallocEnd();
+    sqlite3GlobalConfig.isMallocInit = 0;
+
+#ifndef SQLITE_OMIT_SHUTDOWN_DIRECTORIES
+    /* The heap subsystem has now been shutdown and these values are supposed
+    ** to be NULL or point to memory that was obtained from sqlite3_malloc(),
+    ** which would rely on that heap subsystem; therefore, make sure these
+    ** values cannot refer to heap memory that was just invalidated when the
+    ** heap subsystem was shutdown.  This is only done if the current call to
+    ** this function resulted in the heap subsystem actually being shutdown.
+    */
+    sqlite3_data_directory = 0;
+    sqlite3_temp_directory = 0;
+#endif
+  }
+  if( sqlite3GlobalConfig.isMutexInit ){
+    sqlite3MutexEnd();
+    sqlite3GlobalConfig.isMutexInit = 0;
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** This API allows applications to modify the global configuration of
+** the SQLite library at run-time.
+**
+** This routine should only be called when there are no outstanding
+** database connections or memory allocations.  This routine is not
+** threadsafe.  Failure to heed these warnings can lead to unpredictable
+** behavior.
+*/
+SQLITE_API int sqlite3_config(int op, ...){
+  va_list ap;
+  int rc = SQLITE_OK;
+
+  /* sqlite3_config() shall return SQLITE_MISUSE if it is invoked while
+  ** the SQLite library is in use. */
+  if( sqlite3GlobalConfig.isInit ) return SQLITE_MISUSE_BKPT;
+
+  va_start(ap, op);
+  switch( op ){
+
+    /* Mutex configuration options are only available in a threadsafe
+    ** compile.
+    */
+#if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0  /* IMP: R-54466-46756 */
+    case SQLITE_CONFIG_SINGLETHREAD: {
+      /* EVIDENCE-OF: R-02748-19096 This option sets the threading mode to
+      ** Single-thread. */
+      sqlite3GlobalConfig.bCoreMutex = 0;  /* Disable mutex on core */
+      sqlite3GlobalConfig.bFullMutex = 0;  /* Disable mutex on connections */
+      break;
+    }
+#endif
+#if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0 /* IMP: R-20520-54086 */
+    case SQLITE_CONFIG_MULTITHREAD: {
+      /* EVIDENCE-OF: R-14374-42468 This option sets the threading mode to
+      ** Multi-thread. */
+      sqlite3GlobalConfig.bCoreMutex = 1;  /* Enable mutex on core */
+      sqlite3GlobalConfig.bFullMutex = 0;  /* Disable mutex on connections */
+      break;
+    }
+#endif
+#if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0 /* IMP: R-59593-21810 */
+    case SQLITE_CONFIG_SERIALIZED: {
+      /* EVIDENCE-OF: R-41220-51800 This option sets the threading mode to
+      ** Serialized. */
+      sqlite3GlobalConfig.bCoreMutex = 1;  /* Enable mutex on core */
+      sqlite3GlobalConfig.bFullMutex = 1;  /* Enable mutex on connections */
+      break;
+    }
+#endif
+#if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0 /* IMP: R-63666-48755 */
+    case SQLITE_CONFIG_MUTEX: {
+      /* Specify an alternative mutex implementation */
+      sqlite3GlobalConfig.mutex = *va_arg(ap, sqlite3_mutex_methods*);
+      break;
+    }
+#endif
+#if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0 /* IMP: R-14450-37597 */
+    case SQLITE_CONFIG_GETMUTEX: {
+      /* Retrieve the current mutex implementation */
+      *va_arg(ap, sqlite3_mutex_methods*) = sqlite3GlobalConfig.mutex;
+      break;
+    }
+#endif
+
+    case SQLITE_CONFIG_MALLOC: {
+      /* EVIDENCE-OF: R-55594-21030 The SQLITE_CONFIG_MALLOC option takes a
+      ** single argument which is a pointer to an instance of the
+      ** sqlite3_mem_methods structure. The argument specifies alternative
+      ** low-level memory allocation routines to be used in place of the memory
+      ** allocation routines built into SQLite. */
+      sqlite3GlobalConfig.m = *va_arg(ap, sqlite3_mem_methods*);
+      break;
+    }
+    case SQLITE_CONFIG_GETMALLOC: {
+      /* EVIDENCE-OF: R-51213-46414 The SQLITE_CONFIG_GETMALLOC option takes a
+      ** single argument which is a pointer to an instance of the
+      ** sqlite3_mem_methods structure. The sqlite3_mem_methods structure is
+      ** filled with the currently defined memory allocation routines. */
+      if( sqlite3GlobalConfig.m.xMalloc==0 ) sqlite3MemSetDefault();
+      *va_arg(ap, sqlite3_mem_methods*) = sqlite3GlobalConfig.m;
+      break;
+    }
+    case SQLITE_CONFIG_MEMSTATUS: {
+      /* EVIDENCE-OF: R-61275-35157 The SQLITE_CONFIG_MEMSTATUS option takes
+      ** single argument of type int, interpreted as a boolean, which enables
+      ** or disables the collection of memory allocation statistics. */
+      sqlite3GlobalConfig.bMemstat = va_arg(ap, int);
+      break;
+    }
+    case SQLITE_CONFIG_SCRATCH: {
+      /* EVIDENCE-OF: R-08404-60887 There are three arguments to
+      ** SQLITE_CONFIG_SCRATCH: A pointer an 8-byte aligned memory buffer from
+      ** which the scratch allocations will be drawn, the size of each scratch
+      ** allocation (sz), and the maximum number of scratch allocations (N). */
+      sqlite3GlobalConfig.pScratch = va_arg(ap, void*);
+      sqlite3GlobalConfig.szScratch = va_arg(ap, int);
+      sqlite3GlobalConfig.nScratch = va_arg(ap, int);
+      break;
+    }
+    case SQLITE_CONFIG_PAGECACHE: {
+      /* EVIDENCE-OF: R-18761-36601 There are three arguments to
+      ** SQLITE_CONFIG_PAGECACHE: A pointer to 8-byte aligned memory (pMem),
+      ** the size of each page cache line (sz), and the number of cache lines
+      ** (N). */
+      sqlite3GlobalConfig.pPage = va_arg(ap, void*);
+      sqlite3GlobalConfig.szPage = va_arg(ap, int);
+      sqlite3GlobalConfig.nPage = va_arg(ap, int);
+      break;
+    }
+    case SQLITE_CONFIG_PCACHE_HDRSZ: {
+      /* EVIDENCE-OF: R-39100-27317 The SQLITE_CONFIG_PCACHE_HDRSZ option takes
+      ** a single parameter which is a pointer to an integer and writes into
+      ** that integer the number of extra bytes per page required for each page
+      ** in SQLITE_CONFIG_PAGECACHE. */
+      *va_arg(ap, int*) = 
+          sqlite3HeaderSizeBtree() +
+          sqlite3HeaderSizePcache() +
+          sqlite3HeaderSizePcache1();
+      break;
+    }
+
+    case SQLITE_CONFIG_PCACHE: {
+      /* no-op */
+      break;
+    }
+    case SQLITE_CONFIG_GETPCACHE: {
+      /* now an error */
+      rc = SQLITE_ERROR;
+      break;
+    }
+
+    case SQLITE_CONFIG_PCACHE2: {
+      /* EVIDENCE-OF: R-63325-48378 The SQLITE_CONFIG_PCACHE2 option takes a
+      ** single argument which is a pointer to an sqlite3_pcache_methods2
+      ** object. This object specifies the interface to a custom page cache
+      ** implementation. */
+      sqlite3GlobalConfig.pcache2 = *va_arg(ap, sqlite3_pcache_methods2*);
+      break;
+    }
+    case SQLITE_CONFIG_GETPCACHE2: {
+      /* EVIDENCE-OF: R-22035-46182 The SQLITE_CONFIG_GETPCACHE2 option takes a
+      ** single argument which is a pointer to an sqlite3_pcache_methods2
+      ** object. SQLite copies of the current page cache implementation into
+      ** that object. */
+      if( sqlite3GlobalConfig.pcache2.xInit==0 ){
+        sqlite3PCacheSetDefault();
+      }
+      *va_arg(ap, sqlite3_pcache_methods2*) = sqlite3GlobalConfig.pcache2;
+      break;
+    }
+
+/* EVIDENCE-OF: R-06626-12911 The SQLITE_CONFIG_HEAP option is only
+** available if SQLite is compiled with either SQLITE_ENABLE_MEMSYS3 or
+** SQLITE_ENABLE_MEMSYS5 and returns SQLITE_ERROR if invoked otherwise. */
+#if defined(SQLITE_ENABLE_MEMSYS3) || defined(SQLITE_ENABLE_MEMSYS5)
+    case SQLITE_CONFIG_HEAP: {
+      /* EVIDENCE-OF: R-19854-42126 There are three arguments to
+      ** SQLITE_CONFIG_HEAP: An 8-byte aligned pointer to the memory, the
+      ** number of bytes in the memory buffer, and the minimum allocation size.
+      */
+      sqlite3GlobalConfig.pHeap = va_arg(ap, void*);
+      sqlite3GlobalConfig.nHeap = va_arg(ap, int);
+      sqlite3GlobalConfig.mnReq = va_arg(ap, int);
+
+      if( sqlite3GlobalConfig.mnReq<1 ){
+        sqlite3GlobalConfig.mnReq = 1;
+      }else if( sqlite3GlobalConfig.mnReq>(1<<12) ){
+        /* cap min request size at 2^12 */
+        sqlite3GlobalConfig.mnReq = (1<<12);
+      }
+
+      if( sqlite3GlobalConfig.pHeap==0 ){
+        /* EVIDENCE-OF: R-49920-60189 If the first pointer (the memory pointer)
+        ** is NULL, then SQLite reverts to using its default memory allocator
+        ** (the system malloc() implementation), undoing any prior invocation of
+        ** SQLITE_CONFIG_MALLOC.
+        **
+        ** Setting sqlite3GlobalConfig.m to all zeros will cause malloc to
+        ** revert to its default implementation when sqlite3_initialize() is run
+        */
+        memset(&sqlite3GlobalConfig.m, 0, sizeof(sqlite3GlobalConfig.m));
+      }else{
+        /* EVIDENCE-OF: R-61006-08918 If the memory pointer is not NULL then the
+        ** alternative memory allocator is engaged to handle all of SQLites
+        ** memory allocation needs. */
+#ifdef SQLITE_ENABLE_MEMSYS3
+        sqlite3GlobalConfig.m = *sqlite3MemGetMemsys3();
+#endif
+#ifdef SQLITE_ENABLE_MEMSYS5
+        sqlite3GlobalConfig.m = *sqlite3MemGetMemsys5();
+#endif
+      }
+      break;
+    }
+#endif
+
+    case SQLITE_CONFIG_LOOKASIDE: {
+      sqlite3GlobalConfig.szLookaside = va_arg(ap, int);
+      sqlite3GlobalConfig.nLookaside = va_arg(ap, int);
+      break;
+    }
+    
+    /* Record a pointer to the logger function and its first argument.
+    ** The default is NULL.  Logging is disabled if the function pointer is
+    ** NULL.
+    */
+    case SQLITE_CONFIG_LOG: {
+      /* MSVC is picky about pulling func ptrs from va lists.
+      ** http://support.microsoft.com/kb/47961
+      ** sqlite3GlobalConfig.xLog = va_arg(ap, void(*)(void*,int,const char*));
+      */
+      typedef void(*LOGFUNC_t)(void*,int,const char*);
+      sqlite3GlobalConfig.xLog = va_arg(ap, LOGFUNC_t);
+      sqlite3GlobalConfig.pLogArg = va_arg(ap, void*);
+      break;
+    }
+
+    /* EVIDENCE-OF: R-55548-33817 The compile-time setting for URI filenames
+    ** can be changed at start-time using the
+    ** sqlite3_config(SQLITE_CONFIG_URI,1) or
+    ** sqlite3_config(SQLITE_CONFIG_URI,0) configuration calls.
+    */
+    case SQLITE_CONFIG_URI: {
+      /* EVIDENCE-OF: R-25451-61125 The SQLITE_CONFIG_URI option takes a single
+      ** argument of type int. If non-zero, then URI handling is globally
+      ** enabled. If the parameter is zero, then URI handling is globally
+      ** disabled. */
+      sqlite3GlobalConfig.bOpenUri = va_arg(ap, int);
+      break;
+    }
+
+    case SQLITE_CONFIG_COVERING_INDEX_SCAN: {
+      /* EVIDENCE-OF: R-36592-02772 The SQLITE_CONFIG_COVERING_INDEX_SCAN
+      ** option takes a single integer argument which is interpreted as a
+      ** boolean in order to enable or disable the use of covering indices for
+      ** full table scans in the query optimizer. */
+      sqlite3GlobalConfig.bUseCis = va_arg(ap, int);
+      break;
+    }
+
+#ifdef SQLITE_ENABLE_SQLLOG
+    case SQLITE_CONFIG_SQLLOG: {
+      typedef void(*SQLLOGFUNC_t)(void*, sqlite3*, const char*, int);
+      sqlite3GlobalConfig.xSqllog = va_arg(ap, SQLLOGFUNC_t);
+      sqlite3GlobalConfig.pSqllogArg = va_arg(ap, void *);
+      break;
+    }
+#endif
+
+    case SQLITE_CONFIG_MMAP_SIZE: {
+      /* EVIDENCE-OF: R-58063-38258 SQLITE_CONFIG_MMAP_SIZE takes two 64-bit
+      ** integer (sqlite3_int64) values that are the default mmap size limit
+      ** (the default setting for PRAGMA mmap_size) and the maximum allowed
+      ** mmap size limit. */
+      sqlite3_int64 szMmap = va_arg(ap, sqlite3_int64);
+      sqlite3_int64 mxMmap = va_arg(ap, sqlite3_int64);
+      /* EVIDENCE-OF: R-53367-43190 If either argument to this option is
+      ** negative, then that argument is changed to its compile-time default.
+      **
+      ** EVIDENCE-OF: R-34993-45031 The maximum allowed mmap size will be
+      ** silently truncated if necessary so that it does not exceed the
+      ** compile-time maximum mmap size set by the SQLITE_MAX_MMAP_SIZE
+      ** compile-time option.
+      */
+      if( mxMmap<0 || mxMmap>SQLITE_MAX_MMAP_SIZE ){
+        mxMmap = SQLITE_MAX_MMAP_SIZE;
+      }
+      if( szMmap<0 ) szMmap = SQLITE_DEFAULT_MMAP_SIZE;
+      if( szMmap>mxMmap) szMmap = mxMmap;
+      sqlite3GlobalConfig.mxMmap = mxMmap;
+      sqlite3GlobalConfig.szMmap = szMmap;
+      break;
+    }
+
+#if SQLITE_OS_WIN && defined(SQLITE_WIN32_MALLOC) /* IMP: R-04780-55815 */
+    case SQLITE_CONFIG_WIN32_HEAPSIZE: {
+      /* EVIDENCE-OF: R-34926-03360 SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit
+      ** unsigned integer value that specifies the maximum size of the created
+      ** heap. */
+      sqlite3GlobalConfig.nHeap = va_arg(ap, int);
+      break;
+    }
+#endif
+
+    case SQLITE_CONFIG_PMASZ: {
+      sqlite3GlobalConfig.szPma = va_arg(ap, unsigned int);
+      break;
+    }
+
+    case SQLITE_CONFIG_STMTJRNL_SPILL: {
+      sqlite3GlobalConfig.nStmtSpill = va_arg(ap, int);
+      break;
+    }
+
+    default: {
+      rc = SQLITE_ERROR;
+      break;
+    }
+  }
+  va_end(ap);
+  return rc;
+}
+
+/*
+** Set up the lookaside buffers for a database connection.
+** Return SQLITE_OK on success.  
+** If lookaside is already active, return SQLITE_BUSY.
+**
+** The sz parameter is the number of bytes in each lookaside slot.
+** The cnt parameter is the number of slots.  If pStart is NULL the
+** space for the lookaside memory is obtained from sqlite3_malloc().
+** If pStart is not NULL then it is sz*cnt bytes of memory to use for
+** the lookaside memory.
+*/
+static int setupLookaside(sqlite3 *db, void *pBuf, int sz, int cnt){
+#ifndef SQLITE_OMIT_LOOKASIDE
+  void *pStart;
+  if( db->lookaside.nOut ){
+    return SQLITE_BUSY;
+  }
+  /* Free any existing lookaside buffer for this handle before
+  ** allocating a new one so we don't have to have space for 
+  ** both at the same time.
+  */
+  if( db->lookaside.bMalloced ){
+    sqlite3_free(db->lookaside.pStart);
+  }
+  /* The size of a lookaside slot after ROUNDDOWN8 needs to be larger
+  ** than a pointer to be useful.
+  */
+  sz = ROUNDDOWN8(sz);  /* IMP: R-33038-09382 */
+  if( sz<=(int)sizeof(LookasideSlot*) ) sz = 0;
+  if( cnt<0 ) cnt = 0;
+  if( sz==0 || cnt==0 ){
+    sz = 0;
+    pStart = 0;
+  }else if( pBuf==0 ){
+    sqlite3BeginBenignMalloc();
+    pStart = sqlite3Malloc( sz*cnt );  /* IMP: R-61949-35727 */
+    sqlite3EndBenignMalloc();
+    if( pStart ) cnt = sqlite3MallocSize(pStart)/sz;
+  }else{
+    pStart = pBuf;
+  }
+  db->lookaside.pStart = pStart;
+  db->lookaside.pFree = 0;
+  db->lookaside.sz = (u16)sz;
+  if( pStart ){
+    int i;
+    LookasideSlot *p;
+    assert( sz > (int)sizeof(LookasideSlot*) );
+    p = (LookasideSlot*)pStart;
+    for(i=cnt-1; i>=0; i--){
+      p->pNext = db->lookaside.pFree;
+      db->lookaside.pFree = p;
+      p = (LookasideSlot*)&((u8*)p)[sz];
+    }
+    db->lookaside.pEnd = p;
+    db->lookaside.bDisable = 0;
+    db->lookaside.bMalloced = pBuf==0 ?1:0;
+  }else{
+    db->lookaside.pStart = db;
+    db->lookaside.pEnd = db;
+    db->lookaside.bDisable = 1;
+    db->lookaside.bMalloced = 0;
+  }
+#endif /* SQLITE_OMIT_LOOKASIDE */
+  return SQLITE_OK;
+}
+
+/*
+** Return the mutex associated with a database connection.
+*/
+SQLITE_API sqlite3_mutex *sqlite3_db_mutex(sqlite3 *db){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  return db->mutex;
+}
+
+/*
+** Free up as much memory as we can from the given database
+** connection.
+*/
+SQLITE_API int sqlite3_db_release_memory(sqlite3 *db){
+  int i;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  sqlite3BtreeEnterAll(db);
+  for(i=0; i<db->nDb; i++){
+    Btree *pBt = db->aDb[i].pBt;
+    if( pBt ){
+      Pager *pPager = sqlite3BtreePager(pBt);
+      sqlite3PagerShrink(pPager);
+    }
+  }
+  sqlite3BtreeLeaveAll(db);
+  sqlite3_mutex_leave(db->mutex);
+  return SQLITE_OK;
+}
+
+/*
+** Flush any dirty pages in the pager-cache for any attached database
+** to disk.
+*/
+SQLITE_API int sqlite3_db_cacheflush(sqlite3 *db){
+  int i;
+  int rc = SQLITE_OK;
+  int bSeenBusy = 0;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  sqlite3BtreeEnterAll(db);
+  for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
+    Btree *pBt = db->aDb[i].pBt;
+    if( pBt && sqlite3BtreeIsInTrans(pBt) ){
+      Pager *pPager = sqlite3BtreePager(pBt);
+      rc = sqlite3PagerFlush(pPager);
+      if( rc==SQLITE_BUSY ){
+        bSeenBusy = 1;
+        rc = SQLITE_OK;
+      }
+    }
+  }
+  sqlite3BtreeLeaveAll(db);
+  sqlite3_mutex_leave(db->mutex);
+  return ((rc==SQLITE_OK && bSeenBusy) ? SQLITE_BUSY : rc);
+}
+
+/*
+** Configuration settings for an individual database connection
+*/
+SQLITE_API int sqlite3_db_config(sqlite3 *db, int op, ...){
+  va_list ap;
+  int rc;
+  va_start(ap, op);
+  switch( op ){
+    case SQLITE_DBCONFIG_MAINDBNAME: {
+      db->aDb[0].zDbSName = va_arg(ap,char*);
+      rc = SQLITE_OK;
+      break;
+    }
+    case SQLITE_DBCONFIG_LOOKASIDE: {
+      void *pBuf = va_arg(ap, void*); /* IMP: R-26835-10964 */
+      int sz = va_arg(ap, int);       /* IMP: R-47871-25994 */
+      int cnt = va_arg(ap, int);      /* IMP: R-04460-53386 */
+      rc = setupLookaside(db, pBuf, sz, cnt);
+      break;
+    }
+    default: {
+      static const struct {
+        int op;      /* The opcode */
+        u32 mask;    /* Mask of the bit in sqlite3.flags to set/clear */
+      } aFlagOp[] = {
+        { SQLITE_DBCONFIG_ENABLE_FKEY,           SQLITE_ForeignKeys    },
+        { SQLITE_DBCONFIG_ENABLE_TRIGGER,        SQLITE_EnableTrigger  },
+        { SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER, SQLITE_Fts3Tokenizer  },
+        { SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION, SQLITE_LoadExtension  },
+      };
+      unsigned int i;
+      rc = SQLITE_ERROR; /* IMP: R-42790-23372 */
+      for(i=0; i<ArraySize(aFlagOp); i++){
+        if( aFlagOp[i].op==op ){
+          int onoff = va_arg(ap, int);
+          int *pRes = va_arg(ap, int*);
+          int oldFlags = db->flags;
+          if( onoff>0 ){
+            db->flags |= aFlagOp[i].mask;
+          }else if( onoff==0 ){
+            db->flags &= ~aFlagOp[i].mask;
+          }
+          if( oldFlags!=db->flags ){
+            sqlite3ExpirePreparedStatements(db);
+          }
+          if( pRes ){
+            *pRes = (db->flags & aFlagOp[i].mask)!=0;
+          }
+          rc = SQLITE_OK;
+          break;
+        }
+      }
+      break;
+    }
+  }
+  va_end(ap);
+  return rc;
+}
+
+
+/*
+** Return true if the buffer z[0..n-1] contains all spaces.
+*/
+static int allSpaces(const char *z, int n){
+  while( n>0 && z[n-1]==' ' ){ n--; }
+  return n==0;
+}
+
+/*
+** This is the default collating function named "BINARY" which is always
+** available.
+**
+** If the padFlag argument is not NULL then space padding at the end
+** of strings is ignored.  This implements the RTRIM collation.
+*/
+static int binCollFunc(
+  void *padFlag,
+  int nKey1, const void *pKey1,
+  int nKey2, const void *pKey2
+){
+  int rc, n;
+  n = nKey1<nKey2 ? nKey1 : nKey2;
+  /* EVIDENCE-OF: R-65033-28449 The built-in BINARY collation compares
+  ** strings byte by byte using the memcmp() function from the standard C
+  ** library. */
+  rc = memcmp(pKey1, pKey2, n);
+  if( rc==0 ){
+    if( padFlag
+     && allSpaces(((char*)pKey1)+n, nKey1-n)
+     && allSpaces(((char*)pKey2)+n, nKey2-n)
+    ){
+      /* EVIDENCE-OF: R-31624-24737 RTRIM is like BINARY except that extra
+      ** spaces at the end of either string do not change the result. In other
+      ** words, strings will compare equal to one another as long as they
+      ** differ only in the number of spaces at the end.
+      */
+    }else{
+      rc = nKey1 - nKey2;
+    }
+  }
+  return rc;
+}
+
+/*
+** Another built-in collating sequence: NOCASE. 
+**
+** This collating sequence is intended to be used for "case independent
+** comparison". SQLite's knowledge of upper and lower case equivalents
+** extends only to the 26 characters used in the English language.
+**
+** At the moment there is only a UTF-8 implementation.
+*/
+static int nocaseCollatingFunc(
+  void *NotUsed,
+  int nKey1, const void *pKey1,
+  int nKey2, const void *pKey2
+){
+  int r = sqlite3StrNICmp(
+      (const char *)pKey1, (const char *)pKey2, (nKey1<nKey2)?nKey1:nKey2);
+  UNUSED_PARAMETER(NotUsed);
+  if( 0==r ){
+    r = nKey1-nKey2;
+  }
+  return r;
+}
+
+/*
+** Return the ROWID of the most recent insert
+*/
+SQLITE_API sqlite_int64 sqlite3_last_insert_rowid(sqlite3 *db){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  return db->lastRowid;
+}
+
+/*
+** Return the number of changes in the most recent call to sqlite3_exec().
+*/
+SQLITE_API int sqlite3_changes(sqlite3 *db){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  return db->nChange;
+}
+
+/*
+** Return the number of changes since the database handle was opened.
+*/
+SQLITE_API int sqlite3_total_changes(sqlite3 *db){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  return db->nTotalChange;
+}
+
+/*
+** Close all open savepoints. This function only manipulates fields of the
+** database handle object, it does not close any savepoints that may be open
+** at the b-tree/pager level.
+*/
+SQLITE_PRIVATE void sqlite3CloseSavepoints(sqlite3 *db){
+  while( db->pSavepoint ){
+    Savepoint *pTmp = db->pSavepoint;
+    db->pSavepoint = pTmp->pNext;
+    sqlite3DbFree(db, pTmp);
+  }
+  db->nSavepoint = 0;
+  db->nStatement = 0;
+  db->isTransactionSavepoint = 0;
+}
+
+/*
+** Invoke the destructor function associated with FuncDef p, if any. Except,
+** if this is not the last copy of the function, do not invoke it. Multiple
+** copies of a single function are created when create_function() is called
+** with SQLITE_ANY as the encoding.
+*/
+static void functionDestroy(sqlite3 *db, FuncDef *p){
+  FuncDestructor *pDestructor = p->u.pDestructor;
+  if( pDestructor ){
+    pDestructor->nRef--;
+    if( pDestructor->nRef==0 ){
+      pDestructor->xDestroy(pDestructor->pUserData);
+      sqlite3DbFree(db, pDestructor);
+    }
+  }
+}
+
+/*
+** Disconnect all sqlite3_vtab objects that belong to database connection
+** db. This is called when db is being closed.
+*/
+static void disconnectAllVtab(sqlite3 *db){
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  int i;
+  HashElem *p;
+  sqlite3BtreeEnterAll(db);
+  for(i=0; i<db->nDb; i++){
+    Schema *pSchema = db->aDb[i].pSchema;
+    if( db->aDb[i].pSchema ){
+      for(p=sqliteHashFirst(&pSchema->tblHash); p; p=sqliteHashNext(p)){
+        Table *pTab = (Table *)sqliteHashData(p);
+        if( IsVirtual(pTab) ) sqlite3VtabDisconnect(db, pTab);
+      }
+    }
+  }
+  for(p=sqliteHashFirst(&db->aModule); p; p=sqliteHashNext(p)){
+    Module *pMod = (Module *)sqliteHashData(p);
+    if( pMod->pEpoTab ){
+      sqlite3VtabDisconnect(db, pMod->pEpoTab);
+    }
+  }
+  sqlite3VtabUnlockList(db);
+  sqlite3BtreeLeaveAll(db);
+#else
+  UNUSED_PARAMETER(db);
+#endif
+}
+
+/*
+** Return TRUE if database connection db has unfinalized prepared
+** statements or unfinished sqlite3_backup objects.  
+*/
+static int connectionIsBusy(sqlite3 *db){
+  int j;
+  assert( sqlite3_mutex_held(db->mutex) );
+  if( db->pVdbe ) return 1;
+  for(j=0; j<db->nDb; j++){
+    Btree *pBt = db->aDb[j].pBt;
+    if( pBt && sqlite3BtreeIsInBackup(pBt) ) return 1;
+  }
+  return 0;
+}
+
+/*
+** Close an existing SQLite database
+*/
+static int sqlite3Close(sqlite3 *db, int forceZombie){
+  if( !db ){
+    /* EVIDENCE-OF: R-63257-11740 Calling sqlite3_close() or
+    ** sqlite3_close_v2() with a NULL pointer argument is a harmless no-op. */
+    return SQLITE_OK;
+  }
+  if( !sqlite3SafetyCheckSickOrOk(db) ){
+    return SQLITE_MISUSE_BKPT;
+  }
+  sqlite3_mutex_enter(db->mutex);
+  if( db->mTrace & SQLITE_TRACE_CLOSE ){
+    db->xTrace(SQLITE_TRACE_CLOSE, db->pTraceArg, db, 0);
+  }
+
+  /* Force xDisconnect calls on all virtual tables */
+  disconnectAllVtab(db);
+
+  /* If a transaction is open, the disconnectAllVtab() call above
+  ** will not have called the xDisconnect() method on any virtual
+  ** tables in the db->aVTrans[] array. The following sqlite3VtabRollback()
+  ** call will do so. We need to do this before the check for active
+  ** SQL statements below, as the v-table implementation may be storing
+  ** some prepared statements internally.
+  */
+  sqlite3VtabRollback(db);
+
+  /* Legacy behavior (sqlite3_close() behavior) is to return
+  ** SQLITE_BUSY if the connection can not be closed immediately.
+  */
+  if( !forceZombie && connectionIsBusy(db) ){
+    sqlite3ErrorWithMsg(db, SQLITE_BUSY, "unable to close due to unfinalized "
+       "statements or unfinished backups");
+    sqlite3_mutex_leave(db->mutex);
+    return SQLITE_BUSY;
+  }
+
+#ifdef SQLITE_ENABLE_SQLLOG
+  if( sqlite3GlobalConfig.xSqllog ){
+    /* Closing the handle. Fourth parameter is passed the value 2. */
+    sqlite3GlobalConfig.xSqllog(sqlite3GlobalConfig.pSqllogArg, db, 0, 2);
+  }
+#endif
+
+  /* Convert the connection into a zombie and then close it.
+  */
+  db->magic = SQLITE_MAGIC_ZOMBIE;
+  sqlite3LeaveMutexAndCloseZombie(db);
+  return SQLITE_OK;
+}
+
+/*
+** Two variations on the public interface for closing a database
+** connection. The sqlite3_close() version returns SQLITE_BUSY and
+** leaves the connection option if there are unfinalized prepared
+** statements or unfinished sqlite3_backups.  The sqlite3_close_v2()
+** version forces the connection to become a zombie if there are
+** unclosed resources, and arranges for deallocation when the last
+** prepare statement or sqlite3_backup closes.
+*/
+SQLITE_API int sqlite3_close(sqlite3 *db){ return sqlite3Close(db,0); }
+SQLITE_API int sqlite3_close_v2(sqlite3 *db){ return sqlite3Close(db,1); }
+
+
+/*
+** Close the mutex on database connection db.
+**
+** Furthermore, if database connection db is a zombie (meaning that there
+** has been a prior call to sqlite3_close(db) or sqlite3_close_v2(db)) and
+** every sqlite3_stmt has now been finalized and every sqlite3_backup has
+** finished, then free all resources.
+*/
+SQLITE_PRIVATE void sqlite3LeaveMutexAndCloseZombie(sqlite3 *db){
+  HashElem *i;                    /* Hash table iterator */
+  int j;
+
+  /* If there are outstanding sqlite3_stmt or sqlite3_backup objects
+  ** or if the connection has not yet been closed by sqlite3_close_v2(),
+  ** then just leave the mutex and return.
+  */
+  if( db->magic!=SQLITE_MAGIC_ZOMBIE || connectionIsBusy(db) ){
+    sqlite3_mutex_leave(db->mutex);
+    return;
+  }
+
+  /* If we reach this point, it means that the database connection has
+  ** closed all sqlite3_stmt and sqlite3_backup objects and has been
+  ** passed to sqlite3_close (meaning that it is a zombie).  Therefore,
+  ** go ahead and free all resources.
+  */
+
+  /* If a transaction is open, roll it back. This also ensures that if
+  ** any database schemas have been modified by an uncommitted transaction
+  ** they are reset. And that the required b-tree mutex is held to make
+  ** the pager rollback and schema reset an atomic operation. */
+  sqlite3RollbackAll(db, SQLITE_OK);
+
+  /* Free any outstanding Savepoint structures. */
+  sqlite3CloseSavepoints(db);
+
+  /* Close all database connections */
+  for(j=0; j<db->nDb; j++){
+    struct Db *pDb = &db->aDb[j];
+    if( pDb->pBt ){
+      sqlite3BtreeClose(pDb->pBt);
+      pDb->pBt = 0;
+      if( j!=1 ){
+        pDb->pSchema = 0;
+      }
+    }
+  }
+  /* Clear the TEMP schema separately and last */
+  if( db->aDb[1].pSchema ){
+    sqlite3SchemaClear(db->aDb[1].pSchema);
+  }
+  sqlite3VtabUnlockList(db);
+
+  /* Free up the array of auxiliary databases */
+  sqlite3CollapseDatabaseArray(db);
+  assert( db->nDb<=2 );
+  assert( db->aDb==db->aDbStatic );
+
+  /* Tell the code in notify.c that the connection no longer holds any
+  ** locks and does not require any further unlock-notify callbacks.
+  */
+  sqlite3ConnectionClosed(db);
+
+  for(i=sqliteHashFirst(&db->aFunc); i; i=sqliteHashNext(i)){
+    FuncDef *pNext, *p;
+    p = sqliteHashData(i);
+    do{
+      functionDestroy(db, p);
+      pNext = p->pNext;
+      sqlite3DbFree(db, p);
+      p = pNext;
+    }while( p );
+  }
+  sqlite3HashClear(&db->aFunc);
+  for(i=sqliteHashFirst(&db->aCollSeq); i; i=sqliteHashNext(i)){
+    CollSeq *pColl = (CollSeq *)sqliteHashData(i);
+    /* Invoke any destructors registered for collation sequence user data. */
+    for(j=0; j<3; j++){
+      if( pColl[j].xDel ){
+        pColl[j].xDel(pColl[j].pUser);
+      }
+    }
+    sqlite3DbFree(db, pColl);
+  }
+  sqlite3HashClear(&db->aCollSeq);
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  for(i=sqliteHashFirst(&db->aModule); i; i=sqliteHashNext(i)){
+    Module *pMod = (Module *)sqliteHashData(i);
+    if( pMod->xDestroy ){
+      pMod->xDestroy(pMod->pAux);
+    }
+    sqlite3VtabEponymousTableClear(db, pMod);
+    sqlite3DbFree(db, pMod);
+  }
+  sqlite3HashClear(&db->aModule);
+#endif
+
+  sqlite3Error(db, SQLITE_OK); /* Deallocates any cached error strings. */
+  sqlite3ValueFree(db->pErr);
+  sqlite3CloseExtensions(db);
+#if SQLITE_USER_AUTHENTICATION
+  sqlite3_free(db->auth.zAuthUser);
+  sqlite3_free(db->auth.zAuthPW);
+#endif
+
+  db->magic = SQLITE_MAGIC_ERROR;
+
+  /* The temp-database schema is allocated differently from the other schema
+  ** objects (using sqliteMalloc() directly, instead of sqlite3BtreeSchema()).
+  ** So it needs to be freed here. Todo: Why not roll the temp schema into
+  ** the same sqliteMalloc() as the one that allocates the database 
+  ** structure?
+  */
+  sqlite3DbFree(db, db->aDb[1].pSchema);
+  sqlite3_mutex_leave(db->mutex);
+  db->magic = SQLITE_MAGIC_CLOSED;
+  sqlite3_mutex_free(db->mutex);
+  assert( db->lookaside.nOut==0 );  /* Fails on a lookaside memory leak */
+  if( db->lookaside.bMalloced ){
+    sqlite3_free(db->lookaside.pStart);
+  }
+  sqlite3_free(db);
+}
+
+/*
+** Rollback all database files.  If tripCode is not SQLITE_OK, then
+** any write cursors are invalidated ("tripped" - as in "tripping a circuit
+** breaker") and made to return tripCode if there are any further
+** attempts to use that cursor.  Read cursors remain open and valid
+** but are "saved" in case the table pages are moved around.
+*/
+SQLITE_PRIVATE void sqlite3RollbackAll(sqlite3 *db, int tripCode){
+  int i;
+  int inTrans = 0;
+  int schemaChange;
+  assert( sqlite3_mutex_held(db->mutex) );
+  sqlite3BeginBenignMalloc();
+
+  /* Obtain all b-tree mutexes before making any calls to BtreeRollback(). 
+  ** This is important in case the transaction being rolled back has
+  ** modified the database schema. If the b-tree mutexes are not taken
+  ** here, then another shared-cache connection might sneak in between
+  ** the database rollback and schema reset, which can cause false
+  ** corruption reports in some cases.  */
+  sqlite3BtreeEnterAll(db);
+  schemaChange = (db->flags & SQLITE_InternChanges)!=0 && db->init.busy==0;
+
+  for(i=0; i<db->nDb; i++){
+    Btree *p = db->aDb[i].pBt;
+    if( p ){
+      if( sqlite3BtreeIsInTrans(p) ){
+        inTrans = 1;
+      }
+      sqlite3BtreeRollback(p, tripCode, !schemaChange);
+    }
+  }
+  sqlite3VtabRollback(db);
+  sqlite3EndBenignMalloc();
+
+  if( (db->flags&SQLITE_InternChanges)!=0 && db->init.busy==0 ){
+    sqlite3ExpirePreparedStatements(db);
+    sqlite3ResetAllSchemasOfConnection(db);
+  }
+  sqlite3BtreeLeaveAll(db);
+
+  /* Any deferred constraint violations have now been resolved. */
+  db->nDeferredCons = 0;
+  db->nDeferredImmCons = 0;
+  db->flags &= ~SQLITE_DeferFKs;
+
+  /* If one has been configured, invoke the rollback-hook callback */
+  if( db->xRollbackCallback && (inTrans || !db->autoCommit) ){
+    db->xRollbackCallback(db->pRollbackArg);
+  }
+}
+
+/*
+** Return a static string containing the name corresponding to the error code
+** specified in the argument.
+*/
+#if defined(SQLITE_NEED_ERR_NAME)
+SQLITE_PRIVATE const char *sqlite3ErrName(int rc){
+  const char *zName = 0;
+  int i, origRc = rc;
+  for(i=0; i<2 && zName==0; i++, rc &= 0xff){
+    switch( rc ){
+      case SQLITE_OK:                 zName = "SQLITE_OK";                break;
+      case SQLITE_ERROR:              zName = "SQLITE_ERROR";             break;
+      case SQLITE_INTERNAL:           zName = "SQLITE_INTERNAL";          break;
+      case SQLITE_PERM:               zName = "SQLITE_PERM";              break;
+      case SQLITE_ABORT:              zName = "SQLITE_ABORT";             break;
+      case SQLITE_ABORT_ROLLBACK:     zName = "SQLITE_ABORT_ROLLBACK";    break;
+      case SQLITE_BUSY:               zName = "SQLITE_BUSY";              break;
+      case SQLITE_BUSY_RECOVERY:      zName = "SQLITE_BUSY_RECOVERY";     break;
+      case SQLITE_BUSY_SNAPSHOT:      zName = "SQLITE_BUSY_SNAPSHOT";     break;
+      case SQLITE_LOCKED:             zName = "SQLITE_LOCKED";            break;
+      case SQLITE_LOCKED_SHAREDCACHE: zName = "SQLITE_LOCKED_SHAREDCACHE";break;
+      case SQLITE_NOMEM:              zName = "SQLITE_NOMEM";             break;
+      case SQLITE_READONLY:           zName = "SQLITE_READONLY";          break;
+      case SQLITE_READONLY_RECOVERY:  zName = "SQLITE_READONLY_RECOVERY"; break;
+      case SQLITE_READONLY_CANTLOCK:  zName = "SQLITE_READONLY_CANTLOCK"; break;
+      case SQLITE_READONLY_ROLLBACK:  zName = "SQLITE_READONLY_ROLLBACK"; break;
+      case SQLITE_READONLY_DBMOVED:   zName = "SQLITE_READONLY_DBMOVED";  break;
+      case SQLITE_INTERRUPT:          zName = "SQLITE_INTERRUPT";         break;
+      case SQLITE_IOERR:              zName = "SQLITE_IOERR";             break;
+      case SQLITE_IOERR_READ:         zName = "SQLITE_IOERR_READ";        break;
+      case SQLITE_IOERR_SHORT_READ:   zName = "SQLITE_IOERR_SHORT_READ";  break;
+      case SQLITE_IOERR_WRITE:        zName = "SQLITE_IOERR_WRITE";       break;
+      case SQLITE_IOERR_FSYNC:        zName = "SQLITE_IOERR_FSYNC";       break;
+      case SQLITE_IOERR_DIR_FSYNC:    zName = "SQLITE_IOERR_DIR_FSYNC";   break;
+      case SQLITE_IOERR_TRUNCATE:     zName = "SQLITE_IOERR_TRUNCATE";    break;
+      case SQLITE_IOERR_FSTAT:        zName = "SQLITE_IOERR_FSTAT";       break;
+      case SQLITE_IOERR_UNLOCK:       zName = "SQLITE_IOERR_UNLOCK";      break;
+      case SQLITE_IOERR_RDLOCK:       zName = "SQLITE_IOERR_RDLOCK";      break;
+      case SQLITE_IOERR_DELETE:       zName = "SQLITE_IOERR_DELETE";      break;
+      case SQLITE_IOERR_NOMEM:        zName = "SQLITE_IOERR_NOMEM";       break;
+      case SQLITE_IOERR_ACCESS:       zName = "SQLITE_IOERR_ACCESS";      break;
+      case SQLITE_IOERR_CHECKRESERVEDLOCK:
+                                zName = "SQLITE_IOERR_CHECKRESERVEDLOCK"; break;
+      case SQLITE_IOERR_LOCK:         zName = "SQLITE_IOERR_LOCK";        break;
+      case SQLITE_IOERR_CLOSE:        zName = "SQLITE_IOERR_CLOSE";       break;
+      case SQLITE_IOERR_DIR_CLOSE:    zName = "SQLITE_IOERR_DIR_CLOSE";   break;
+      case SQLITE_IOERR_SHMOPEN:      zName = "SQLITE_IOERR_SHMOPEN";     break;
+      case SQLITE_IOERR_SHMSIZE:      zName = "SQLITE_IOERR_SHMSIZE";     break;
+      case SQLITE_IOERR_SHMLOCK:      zName = "SQLITE_IOERR_SHMLOCK";     break;
+      case SQLITE_IOERR_SHMMAP:       zName = "SQLITE_IOERR_SHMMAP";      break;
+      case SQLITE_IOERR_SEEK:         zName = "SQLITE_IOERR_SEEK";        break;
+      case SQLITE_IOERR_DELETE_NOENT: zName = "SQLITE_IOERR_DELETE_NOENT";break;
+      case SQLITE_IOERR_MMAP:         zName = "SQLITE_IOERR_MMAP";        break;
+      case SQLITE_IOERR_GETTEMPPATH:  zName = "SQLITE_IOERR_GETTEMPPATH"; break;
+      case SQLITE_IOERR_CONVPATH:     zName = "SQLITE_IOERR_CONVPATH";    break;
+      case SQLITE_CORRUPT:            zName = "SQLITE_CORRUPT";           break;
+      case SQLITE_CORRUPT_VTAB:       zName = "SQLITE_CORRUPT_VTAB";      break;
+      case SQLITE_NOTFOUND:           zName = "SQLITE_NOTFOUND";          break;
+      case SQLITE_FULL:               zName = "SQLITE_FULL";              break;
+      case SQLITE_CANTOPEN:           zName = "SQLITE_CANTOPEN";          break;
+      case SQLITE_CANTOPEN_NOTEMPDIR: zName = "SQLITE_CANTOPEN_NOTEMPDIR";break;
+      case SQLITE_CANTOPEN_ISDIR:     zName = "SQLITE_CANTOPEN_ISDIR";    break;
+      case SQLITE_CANTOPEN_FULLPATH:  zName = "SQLITE_CANTOPEN_FULLPATH"; break;
+      case SQLITE_CANTOPEN_CONVPATH:  zName = "SQLITE_CANTOPEN_CONVPATH"; break;
+      case SQLITE_PROTOCOL:           zName = "SQLITE_PROTOCOL";          break;
+      case SQLITE_EMPTY:              zName = "SQLITE_EMPTY";             break;
+      case SQLITE_SCHEMA:             zName = "SQLITE_SCHEMA";            break;
+      case SQLITE_TOOBIG:             zName = "SQLITE_TOOBIG";            break;
+      case SQLITE_CONSTRAINT:         zName = "SQLITE_CONSTRAINT";        break;
+      case SQLITE_CONSTRAINT_UNIQUE:  zName = "SQLITE_CONSTRAINT_UNIQUE"; break;
+      case SQLITE_CONSTRAINT_TRIGGER: zName = "SQLITE_CONSTRAINT_TRIGGER";break;
+      case SQLITE_CONSTRAINT_FOREIGNKEY:
+                                zName = "SQLITE_CONSTRAINT_FOREIGNKEY";   break;
+      case SQLITE_CONSTRAINT_CHECK:   zName = "SQLITE_CONSTRAINT_CHECK";  break;
+      case SQLITE_CONSTRAINT_PRIMARYKEY:
+                                zName = "SQLITE_CONSTRAINT_PRIMARYKEY";   break;
+      case SQLITE_CONSTRAINT_NOTNULL: zName = "SQLITE_CONSTRAINT_NOTNULL";break;
+      case SQLITE_CONSTRAINT_COMMITHOOK:
+                                zName = "SQLITE_CONSTRAINT_COMMITHOOK";   break;
+      case SQLITE_CONSTRAINT_VTAB:    zName = "SQLITE_CONSTRAINT_VTAB";   break;
+      case SQLITE_CONSTRAINT_FUNCTION:
+                                zName = "SQLITE_CONSTRAINT_FUNCTION";     break;
+      case SQLITE_CONSTRAINT_ROWID:   zName = "SQLITE_CONSTRAINT_ROWID";  break;
+      case SQLITE_MISMATCH:           zName = "SQLITE_MISMATCH";          break;
+      case SQLITE_MISUSE:             zName = "SQLITE_MISUSE";            break;
+      case SQLITE_NOLFS:              zName = "SQLITE_NOLFS";             break;
+      case SQLITE_AUTH:               zName = "SQLITE_AUTH";              break;
+      case SQLITE_FORMAT:             zName = "SQLITE_FORMAT";            break;
+      case SQLITE_RANGE:              zName = "SQLITE_RANGE";             break;
+      case SQLITE_NOTADB:             zName = "SQLITE_NOTADB";            break;
+      case SQLITE_ROW:                zName = "SQLITE_ROW";               break;
+      case SQLITE_NOTICE:             zName = "SQLITE_NOTICE";            break;
+      case SQLITE_NOTICE_RECOVER_WAL: zName = "SQLITE_NOTICE_RECOVER_WAL";break;
+      case SQLITE_NOTICE_RECOVER_ROLLBACK:
+                                zName = "SQLITE_NOTICE_RECOVER_ROLLBACK"; break;
+      case SQLITE_WARNING:            zName = "SQLITE_WARNING";           break;
+      case SQLITE_WARNING_AUTOINDEX:  zName = "SQLITE_WARNING_AUTOINDEX"; break;
+      case SQLITE_DONE:               zName = "SQLITE_DONE";              break;
+    }
+  }
+  if( zName==0 ){
+    static char zBuf[50];
+    sqlite3_snprintf(sizeof(zBuf), zBuf, "SQLITE_UNKNOWN(%d)", origRc);
+    zName = zBuf;
+  }
+  return zName;
+}
+#endif
+
+/*
+** Return a static string that describes the kind of error specified in the
+** argument.
+*/
+SQLITE_PRIVATE const char *sqlite3ErrStr(int rc){
+  static const char* const aMsg[] = {
+    /* SQLITE_OK          */ "not an error",
+    /* SQLITE_ERROR       */ "SQL logic error or missing database",
+    /* SQLITE_INTERNAL    */ 0,
+    /* SQLITE_PERM        */ "access permission denied",
+    /* SQLITE_ABORT       */ "callback requested query abort",
+    /* SQLITE_BUSY        */ "database is locked",
+    /* SQLITE_LOCKED      */ "database table is locked",
+    /* SQLITE_NOMEM       */ "out of memory",
+    /* SQLITE_READONLY    */ "attempt to write a readonly database",
+    /* SQLITE_INTERRUPT   */ "interrupted",
+    /* SQLITE_IOERR       */ "disk I/O error",
+    /* SQLITE_CORRUPT     */ "database disk image is malformed",
+    /* SQLITE_NOTFOUND    */ "unknown operation",
+    /* SQLITE_FULL        */ "database or disk is full",
+    /* SQLITE_CANTOPEN    */ "unable to open database file",
+    /* SQLITE_PROTOCOL    */ "locking protocol",
+    /* SQLITE_EMPTY       */ "table contains no data",
+    /* SQLITE_SCHEMA      */ "database schema has changed",
+    /* SQLITE_TOOBIG      */ "string or blob too big",
+    /* SQLITE_CONSTRAINT  */ "constraint failed",
+    /* SQLITE_MISMATCH    */ "datatype mismatch",
+    /* SQLITE_MISUSE      */ "library routine called out of sequence",
+    /* SQLITE_NOLFS       */ "large file support is disabled",
+    /* SQLITE_AUTH        */ "authorization denied",
+    /* SQLITE_FORMAT      */ "auxiliary database format error",
+    /* SQLITE_RANGE       */ "bind or column index out of range",
+    /* SQLITE_NOTADB      */ "file is encrypted or is not a database",
+  };
+  const char *zErr = "unknown error";
+  switch( rc ){
+    case SQLITE_ABORT_ROLLBACK: {
+      zErr = "abort due to ROLLBACK";
+      break;
+    }
+    default: {
+      rc &= 0xff;
+      if( ALWAYS(rc>=0) && rc<ArraySize(aMsg) && aMsg[rc]!=0 ){
+        zErr = aMsg[rc];
+      }
+      break;
+    }
+  }
+  return zErr;
+}
+
+/*
+** This routine implements a busy callback that sleeps and tries
+** again until a timeout value is reached.  The timeout value is
+** an integer number of milliseconds passed in as the first
+** argument.
+*/
+static int sqliteDefaultBusyCallback(
+ void *ptr,               /* Database connection */
+ int count                /* Number of times table has been busy */
+){
+#if SQLITE_OS_WIN || HAVE_USLEEP
+  static const u8 delays[] =
+     { 1, 2, 5, 10, 15, 20, 25, 25,  25,  50,  50, 100 };
+  static const u8 totals[] =
+     { 0, 1, 3,  8, 18, 33, 53, 78, 103, 128, 178, 228 };
+# define NDELAY ArraySize(delays)
+  sqlite3 *db = (sqlite3 *)ptr;
+  int timeout = db->busyTimeout;
+  int delay, prior;
+
+  assert( count>=0 );
+  if( count < NDELAY ){
+    delay = delays[count];
+    prior = totals[count];
+  }else{
+    delay = delays[NDELAY-1];
+    prior = totals[NDELAY-1] + delay*(count-(NDELAY-1));
+  }
+  if( prior + delay > timeout ){
+    delay = timeout - prior;
+    if( delay<=0 ) return 0;
+  }
+  sqlite3OsSleep(db->pVfs, delay*1000);
+  return 1;
+#else
+  sqlite3 *db = (sqlite3 *)ptr;
+  int timeout = ((sqlite3 *)ptr)->busyTimeout;
+  if( (count+1)*1000 > timeout ){
+    return 0;
+  }
+  sqlite3OsSleep(db->pVfs, 1000000);
+  return 1;
+#endif
+}
+
+/*
+** Invoke the given busy handler.
+**
+** This routine is called when an operation failed with a lock.
+** If this routine returns non-zero, the lock is retried.  If it
+** returns 0, the operation aborts with an SQLITE_BUSY error.
+*/
+SQLITE_PRIVATE int sqlite3InvokeBusyHandler(BusyHandler *p){
+  int rc;
+  if( NEVER(p==0) || p->xFunc==0 || p->nBusy<0 ) return 0;
+  rc = p->xFunc(p->pArg, p->nBusy);
+  if( rc==0 ){
+    p->nBusy = -1;
+  }else{
+    p->nBusy++;
+  }
+  return rc; 
+}
+
+/*
+** This routine sets the busy callback for an Sqlite database to the
+** given callback function with the given argument.
+*/
+SQLITE_API int sqlite3_busy_handler(
+  sqlite3 *db,
+  int (*xBusy)(void*,int),
+  void *pArg
+){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  db->busyHandler.xFunc = xBusy;
+  db->busyHandler.pArg = pArg;
+  db->busyHandler.nBusy = 0;
+  db->busyTimeout = 0;
+  sqlite3_mutex_leave(db->mutex);
+  return SQLITE_OK;
+}
+
+#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
+/*
+** This routine sets the progress callback for an Sqlite database to the
+** given callback function with the given argument. The progress callback will
+** be invoked every nOps opcodes.
+*/
+SQLITE_API void sqlite3_progress_handler(
+  sqlite3 *db, 
+  int nOps,
+  int (*xProgress)(void*), 
+  void *pArg
+){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return;
+  }
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  if( nOps>0 ){
+    db->xProgress = xProgress;
+    db->nProgressOps = (unsigned)nOps;
+    db->pProgressArg = pArg;
+  }else{
+    db->xProgress = 0;
+    db->nProgressOps = 0;
+    db->pProgressArg = 0;
+  }
+  sqlite3_mutex_leave(db->mutex);
+}
+#endif
+
+
+/*
+** This routine installs a default busy handler that waits for the
+** specified number of milliseconds before returning 0.
+*/
+SQLITE_API int sqlite3_busy_timeout(sqlite3 *db, int ms){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
+#endif
+  if( ms>0 ){
+    sqlite3_busy_handler(db, sqliteDefaultBusyCallback, (void*)db);
+    db->busyTimeout = ms;
+  }else{
+    sqlite3_busy_handler(db, 0, 0);
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Cause any pending operation to stop at its earliest opportunity.
+*/
+SQLITE_API void sqlite3_interrupt(sqlite3 *db){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return;
+  }
+#endif
+  db->u1.isInterrupted = 1;
+}
+
+
+/*
+** This function is exactly the same as sqlite3_create_function(), except
+** that it is designed to be called by internal code. The difference is
+** that if a malloc() fails in sqlite3_create_function(), an error code
+** is returned and the mallocFailed flag cleared. 
+*/
+SQLITE_PRIVATE int sqlite3CreateFunc(
+  sqlite3 *db,
+  const char *zFunctionName,
+  int nArg,
+  int enc,
+  void *pUserData,
+  void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
+  void (*xStep)(sqlite3_context*,int,sqlite3_value **),
+  void (*xFinal)(sqlite3_context*),
+  FuncDestructor *pDestructor
+){
+  FuncDef *p;
+  int nName;
+  int extraFlags;
+
+  assert( sqlite3_mutex_held(db->mutex) );
+  if( zFunctionName==0 ||
+      (xSFunc && (xFinal || xStep)) || 
+      (!xSFunc && (xFinal && !xStep)) ||
+      (!xSFunc && (!xFinal && xStep)) ||
+      (nArg<-1 || nArg>SQLITE_MAX_FUNCTION_ARG) ||
+      (255<(nName = sqlite3Strlen30( zFunctionName))) ){
+    return SQLITE_MISUSE_BKPT;
+  }
+
+  assert( SQLITE_FUNC_CONSTANT==SQLITE_DETERMINISTIC );
+  extraFlags = enc &  SQLITE_DETERMINISTIC;
+  enc &= (SQLITE_FUNC_ENCMASK|SQLITE_ANY);
+  
+#ifndef SQLITE_OMIT_UTF16
+  /* If SQLITE_UTF16 is specified as the encoding type, transform this
+  ** to one of SQLITE_UTF16LE or SQLITE_UTF16BE using the
+  ** SQLITE_UTF16NATIVE macro. SQLITE_UTF16 is not used internally.
+  **
+  ** If SQLITE_ANY is specified, add three versions of the function
+  ** to the hash table.
+  */
+  if( enc==SQLITE_UTF16 ){
+    enc = SQLITE_UTF16NATIVE;
+  }else if( enc==SQLITE_ANY ){
+    int rc;
+    rc = sqlite3CreateFunc(db, zFunctionName, nArg, SQLITE_UTF8|extraFlags,
+         pUserData, xSFunc, xStep, xFinal, pDestructor);
+    if( rc==SQLITE_OK ){
+      rc = sqlite3CreateFunc(db, zFunctionName, nArg, SQLITE_UTF16LE|extraFlags,
+          pUserData, xSFunc, xStep, xFinal, pDestructor);
+    }
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    enc = SQLITE_UTF16BE;
+  }
+#else
+  enc = SQLITE_UTF8;
+#endif
+  
+  /* Check if an existing function is being overridden or deleted. If so,
+  ** and there are active VMs, then return SQLITE_BUSY. If a function
+  ** is being overridden/deleted but there are no active VMs, allow the
+  ** operation to continue but invalidate all precompiled statements.
+  */
+  p = sqlite3FindFunction(db, zFunctionName, nArg, (u8)enc, 0);
+  if( p && (p->funcFlags & SQLITE_FUNC_ENCMASK)==enc && p->nArg==nArg ){
+    if( db->nVdbeActive ){
+      sqlite3ErrorWithMsg(db, SQLITE_BUSY, 
+        "unable to delete/modify user-function due to active statements");
+      assert( !db->mallocFailed );
+      return SQLITE_BUSY;
+    }else{
+      sqlite3ExpirePreparedStatements(db);
+    }
+  }
+
+  p = sqlite3FindFunction(db, zFunctionName, nArg, (u8)enc, 1);
+  assert(p || db->mallocFailed);
+  if( !p ){
+    return SQLITE_NOMEM_BKPT;
+  }
+
+  /* If an older version of the function with a configured destructor is
+  ** being replaced invoke the destructor function here. */
+  functionDestroy(db, p);
+
+  if( pDestructor ){
+    pDestructor->nRef++;
+  }
+  p->u.pDestructor = pDestructor;
+  p->funcFlags = (p->funcFlags & SQLITE_FUNC_ENCMASK) | extraFlags;
+  testcase( p->funcFlags & SQLITE_DETERMINISTIC );
+  p->xSFunc = xSFunc ? xSFunc : xStep;
+  p->xFinalize = xFinal;
+  p->pUserData = pUserData;
+  p->nArg = (u16)nArg;
+  return SQLITE_OK;
+}
+
+/*
+** Create new user functions.
+*/
+SQLITE_API int sqlite3_create_function(
+  sqlite3 *db,
+  const char *zFunc,
+  int nArg,
+  int enc,
+  void *p,
+  void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
+  void (*xStep)(sqlite3_context*,int,sqlite3_value **),
+  void (*xFinal)(sqlite3_context*)
+){
+  return sqlite3_create_function_v2(db, zFunc, nArg, enc, p, xSFunc, xStep,
+                                    xFinal, 0);
+}
+
+SQLITE_API int sqlite3_create_function_v2(
+  sqlite3 *db,
+  const char *zFunc,
+  int nArg,
+  int enc,
+  void *p,
+  void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
+  void (*xStep)(sqlite3_context*,int,sqlite3_value **),
+  void (*xFinal)(sqlite3_context*),
+  void (*xDestroy)(void *)
+){
+  int rc = SQLITE_ERROR;
+  FuncDestructor *pArg = 0;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    return SQLITE_MISUSE_BKPT;
+  }
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  if( xDestroy ){
+    pArg = (FuncDestructor *)sqlite3DbMallocZero(db, sizeof(FuncDestructor));
+    if( !pArg ){
+      xDestroy(p);
+      goto out;
+    }
+    pArg->xDestroy = xDestroy;
+    pArg->pUserData = p;
+  }
+  rc = sqlite3CreateFunc(db, zFunc, nArg, enc, p, xSFunc, xStep, xFinal, pArg);
+  if( pArg && pArg->nRef==0 ){
+    assert( rc!=SQLITE_OK );
+    xDestroy(p);
+    sqlite3DbFree(db, pArg);
+  }
+
+ out:
+  rc = sqlite3ApiExit(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API int sqlite3_create_function16(
+  sqlite3 *db,
+  const void *zFunctionName,
+  int nArg,
+  int eTextRep,
+  void *p,
+  void (*xSFunc)(sqlite3_context*,int,sqlite3_value**),
+  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+  void (*xFinal)(sqlite3_context*)
+){
+  int rc;
+  char *zFunc8;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) || zFunctionName==0 ) return SQLITE_MISUSE_BKPT;
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  assert( !db->mallocFailed );
+  zFunc8 = sqlite3Utf16to8(db, zFunctionName, -1, SQLITE_UTF16NATIVE);
+  rc = sqlite3CreateFunc(db, zFunc8, nArg, eTextRep, p, xSFunc,xStep,xFinal,0);
+  sqlite3DbFree(db, zFunc8);
+  rc = sqlite3ApiExit(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+#endif
+
+
+/*
+** Declare that a function has been overloaded by a virtual table.
+**
+** If the function already exists as a regular global function, then
+** this routine is a no-op.  If the function does not exist, then create
+** a new one that always throws a run-time error.  
+**
+** When virtual tables intend to provide an overloaded function, they
+** should call this routine to make sure the global function exists.
+** A global function must exist in order for name resolution to work
+** properly.
+*/
+SQLITE_API int sqlite3_overload_function(
+  sqlite3 *db,
+  const char *zName,
+  int nArg
+){
+  int rc = SQLITE_OK;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) || zName==0 || nArg<-2 ){
+    return SQLITE_MISUSE_BKPT;
+  }
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  if( sqlite3FindFunction(db, zName, nArg, SQLITE_UTF8, 0)==0 ){
+    rc = sqlite3CreateFunc(db, zName, nArg, SQLITE_UTF8,
+                           0, sqlite3InvalidFunction, 0, 0, 0);
+  }
+  rc = sqlite3ApiExit(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+#ifndef SQLITE_OMIT_TRACE
+/*
+** Register a trace function.  The pArg from the previously registered trace
+** is returned.  
+**
+** A NULL trace function means that no tracing is executes.  A non-NULL
+** trace is a pointer to a function that is invoked at the start of each
+** SQL statement.
+*/
+#ifndef SQLITE_OMIT_DEPRECATED
+SQLITE_API void *sqlite3_trace(sqlite3 *db, void(*xTrace)(void*,const char*), void *pArg){
+  void *pOld;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  pOld = db->pTraceArg;
+  db->mTrace = xTrace ? SQLITE_TRACE_LEGACY : 0;
+  db->xTrace = (int(*)(u32,void*,void*,void*))xTrace;
+  db->pTraceArg = pArg;
+  sqlite3_mutex_leave(db->mutex);
+  return pOld;
+}
+#endif /* SQLITE_OMIT_DEPRECATED */
+
+/* Register a trace callback using the version-2 interface.
+*/
+SQLITE_API int sqlite3_trace_v2(
+  sqlite3 *db,                               /* Trace this connection */
+  unsigned mTrace,                           /* Mask of events to be traced */
+  int(*xTrace)(unsigned,void*,void*,void*),  /* Callback to invoke */
+  void *pArg                                 /* Context */
+){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    return SQLITE_MISUSE_BKPT;
+  }
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  if( mTrace==0 ) xTrace = 0;
+  if( xTrace==0 ) mTrace = 0;
+  db->mTrace = mTrace;
+  db->xTrace = xTrace;
+  db->pTraceArg = pArg;
+  sqlite3_mutex_leave(db->mutex);
+  return SQLITE_OK;
+}
+
+#ifndef SQLITE_OMIT_DEPRECATED
+/*
+** Register a profile function.  The pArg from the previously registered 
+** profile function is returned.  
+**
+** A NULL profile function means that no profiling is executes.  A non-NULL
+** profile is a pointer to a function that is invoked at the conclusion of
+** each SQL statement that is run.
+*/
+SQLITE_API void *sqlite3_profile(
+  sqlite3 *db,
+  void (*xProfile)(void*,const char*,sqlite_uint64),
+  void *pArg
+){
+  void *pOld;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  pOld = db->pProfileArg;
+  db->xProfile = xProfile;
+  db->pProfileArg = pArg;
+  sqlite3_mutex_leave(db->mutex);
+  return pOld;
+}
+#endif /* SQLITE_OMIT_DEPRECATED */
+#endif /* SQLITE_OMIT_TRACE */
+
+/*
+** Register a function to be invoked when a transaction commits.
+** If the invoked function returns non-zero, then the commit becomes a
+** rollback.
+*/
+SQLITE_API void *sqlite3_commit_hook(
+  sqlite3 *db,              /* Attach the hook to this database */
+  int (*xCallback)(void*),  /* Function to invoke on each commit */
+  void *pArg                /* Argument to the function */
+){
+  void *pOld;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  pOld = db->pCommitArg;
+  db->xCommitCallback = xCallback;
+  db->pCommitArg = pArg;
+  sqlite3_mutex_leave(db->mutex);
+  return pOld;
+}
+
+/*
+** Register a callback to be invoked each time a row is updated,
+** inserted or deleted using this database connection.
+*/
+SQLITE_API void *sqlite3_update_hook(
+  sqlite3 *db,              /* Attach the hook to this database */
+  void (*xCallback)(void*,int,char const *,char const *,sqlite_int64),
+  void *pArg                /* Argument to the function */
+){
+  void *pRet;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  pRet = db->pUpdateArg;
+  db->xUpdateCallback = xCallback;
+  db->pUpdateArg = pArg;
+  sqlite3_mutex_leave(db->mutex);
+  return pRet;
+}
+
+/*
+** Register a callback to be invoked each time a transaction is rolled
+** back by this database connection.
+*/
+SQLITE_API void *sqlite3_rollback_hook(
+  sqlite3 *db,              /* Attach the hook to this database */
+  void (*xCallback)(void*), /* Callback function */
+  void *pArg                /* Argument to the function */
+){
+  void *pRet;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  pRet = db->pRollbackArg;
+  db->xRollbackCallback = xCallback;
+  db->pRollbackArg = pArg;
+  sqlite3_mutex_leave(db->mutex);
+  return pRet;
+}
+
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+/*
+** Register a callback to be invoked each time a row is updated,
+** inserted or deleted using this database connection.
+*/
+SQLITE_API void *sqlite3_preupdate_hook(
+  sqlite3 *db,              /* Attach the hook to this database */
+  void(*xCallback)(         /* Callback function */
+    void*,sqlite3*,int,char const*,char const*,sqlite3_int64,sqlite3_int64),
+  void *pArg                /* First callback argument */
+){
+  void *pRet;
+  sqlite3_mutex_enter(db->mutex);
+  pRet = db->pPreUpdateArg;
+  db->xPreUpdateCallback = xCallback;
+  db->pPreUpdateArg = pArg;
+  sqlite3_mutex_leave(db->mutex);
+  return pRet;
+}
+#endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
+
+#ifndef SQLITE_OMIT_WAL
+/*
+** The sqlite3_wal_hook() callback registered by sqlite3_wal_autocheckpoint().
+** Invoke sqlite3_wal_checkpoint if the number of frames in the log file
+** is greater than sqlite3.pWalArg cast to an integer (the value configured by
+** wal_autocheckpoint()).
+*/ 
+SQLITE_PRIVATE int sqlite3WalDefaultHook(
+  void *pClientData,     /* Argument */
+  sqlite3 *db,           /* Connection */
+  const char *zDb,       /* Database */
+  int nFrame             /* Size of WAL */
+){
+  if( nFrame>=SQLITE_PTR_TO_INT(pClientData) ){
+    sqlite3BeginBenignMalloc();
+    sqlite3_wal_checkpoint(db, zDb);
+    sqlite3EndBenignMalloc();
+  }
+  return SQLITE_OK;
+}
+#endif /* SQLITE_OMIT_WAL */
+
+/*
+** Configure an sqlite3_wal_hook() callback to automatically checkpoint
+** a database after committing a transaction if there are nFrame or
+** more frames in the log file. Passing zero or a negative value as the
+** nFrame parameter disables automatic checkpoints entirely.
+**
+** The callback registered by this function replaces any existing callback
+** registered using sqlite3_wal_hook(). Likewise, registering a callback
+** using sqlite3_wal_hook() disables the automatic checkpoint mechanism
+** configured by this function.
+*/
+SQLITE_API int sqlite3_wal_autocheckpoint(sqlite3 *db, int nFrame){
+#ifdef SQLITE_OMIT_WAL
+  UNUSED_PARAMETER(db);
+  UNUSED_PARAMETER(nFrame);
+#else
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
+#endif
+  if( nFrame>0 ){
+    sqlite3_wal_hook(db, sqlite3WalDefaultHook, SQLITE_INT_TO_PTR(nFrame));
+  }else{
+    sqlite3_wal_hook(db, 0, 0);
+  }
+#endif
+  return SQLITE_OK;
+}
+
+/*
+** Register a callback to be invoked each time a transaction is written
+** into the write-ahead-log by this database connection.
+*/
+SQLITE_API void *sqlite3_wal_hook(
+  sqlite3 *db,                    /* Attach the hook to this db handle */
+  int(*xCallback)(void *, sqlite3*, const char*, int),
+  void *pArg                      /* First argument passed to xCallback() */
+){
+#ifndef SQLITE_OMIT_WAL
+  void *pRet;
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  pRet = db->pWalArg;
+  db->xWalCallback = xCallback;
+  db->pWalArg = pArg;
+  sqlite3_mutex_leave(db->mutex);
+  return pRet;
+#else
+  return 0;
+#endif
+}
+
+/*
+** Checkpoint database zDb.
+*/
+SQLITE_API int sqlite3_wal_checkpoint_v2(
+  sqlite3 *db,                    /* Database handle */
+  const char *zDb,                /* Name of attached database (or NULL) */
+  int eMode,                      /* SQLITE_CHECKPOINT_* value */
+  int *pnLog,                     /* OUT: Size of WAL log in frames */
+  int *pnCkpt                     /* OUT: Total number of frames checkpointed */
+){
+#ifdef SQLITE_OMIT_WAL
+  return SQLITE_OK;
+#else
+  int rc;                         /* Return code */
+  int iDb = SQLITE_MAX_ATTACHED;  /* sqlite3.aDb[] index of db to checkpoint */
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
+#endif
+
+  /* Initialize the output variables to -1 in case an error occurs. */
+  if( pnLog ) *pnLog = -1;
+  if( pnCkpt ) *pnCkpt = -1;
+
+  assert( SQLITE_CHECKPOINT_PASSIVE==0 );
+  assert( SQLITE_CHECKPOINT_FULL==1 );
+  assert( SQLITE_CHECKPOINT_RESTART==2 );
+  assert( SQLITE_CHECKPOINT_TRUNCATE==3 );
+  if( eMode<SQLITE_CHECKPOINT_PASSIVE || eMode>SQLITE_CHECKPOINT_TRUNCATE ){
+    /* EVIDENCE-OF: R-03996-12088 The M parameter must be a valid checkpoint
+    ** mode: */
+    return SQLITE_MISUSE;
+  }
+
+  sqlite3_mutex_enter(db->mutex);
+  if( zDb && zDb[0] ){
+    iDb = sqlite3FindDbName(db, zDb);
+  }
+  if( iDb<0 ){
+    rc = SQLITE_ERROR;
+    sqlite3ErrorWithMsg(db, SQLITE_ERROR, "unknown database: %s", zDb);
+  }else{
+    db->busyHandler.nBusy = 0;
+    rc = sqlite3Checkpoint(db, iDb, eMode, pnLog, pnCkpt);
+    sqlite3Error(db, rc);
+  }
+  rc = sqlite3ApiExit(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+#endif
+}
+
+
+/*
+** Checkpoint database zDb. If zDb is NULL, or if the buffer zDb points
+** to contains a zero-length string, all attached databases are 
+** checkpointed.
+*/
+SQLITE_API int sqlite3_wal_checkpoint(sqlite3 *db, const char *zDb){
+  /* EVIDENCE-OF: R-41613-20553 The sqlite3_wal_checkpoint(D,X) is equivalent to
+  ** sqlite3_wal_checkpoint_v2(D,X,SQLITE_CHECKPOINT_PASSIVE,0,0). */
+  return sqlite3_wal_checkpoint_v2(db,zDb,SQLITE_CHECKPOINT_PASSIVE,0,0);
+}
+
+#ifndef SQLITE_OMIT_WAL
+/*
+** Run a checkpoint on database iDb. This is a no-op if database iDb is
+** not currently open in WAL mode.
+**
+** If a transaction is open on the database being checkpointed, this 
+** function returns SQLITE_LOCKED and a checkpoint is not attempted. If 
+** an error occurs while running the checkpoint, an SQLite error code is 
+** returned (i.e. SQLITE_IOERR). Otherwise, SQLITE_OK.
+**
+** The mutex on database handle db should be held by the caller. The mutex
+** associated with the specific b-tree being checkpointed is taken by
+** this function while the checkpoint is running.
+**
+** If iDb is passed SQLITE_MAX_ATTACHED, then all attached databases are
+** checkpointed. If an error is encountered it is returned immediately -
+** no attempt is made to checkpoint any remaining databases.
+**
+** Parameter eMode is one of SQLITE_CHECKPOINT_PASSIVE, FULL or RESTART.
+*/
+SQLITE_PRIVATE int sqlite3Checkpoint(sqlite3 *db, int iDb, int eMode, int *pnLog, int *pnCkpt){
+  int rc = SQLITE_OK;             /* Return code */
+  int i;                          /* Used to iterate through attached dbs */
+  int bBusy = 0;                  /* True if SQLITE_BUSY has been encountered */
+
+  assert( sqlite3_mutex_held(db->mutex) );
+  assert( !pnLog || *pnLog==-1 );
+  assert( !pnCkpt || *pnCkpt==-1 );
+
+  for(i=0; i<db->nDb && rc==SQLITE_OK; i++){
+    if( i==iDb || iDb==SQLITE_MAX_ATTACHED ){
+      rc = sqlite3BtreeCheckpoint(db->aDb[i].pBt, eMode, pnLog, pnCkpt);
+      pnLog = 0;
+      pnCkpt = 0;
+      if( rc==SQLITE_BUSY ){
+        bBusy = 1;
+        rc = SQLITE_OK;
+      }
+    }
+  }
+
+  return (rc==SQLITE_OK && bBusy) ? SQLITE_BUSY : rc;
+}
+#endif /* SQLITE_OMIT_WAL */
+
+/*
+** This function returns true if main-memory should be used instead of
+** a temporary file for transient pager files and statement journals.
+** The value returned depends on the value of db->temp_store (runtime
+** parameter) and the compile time value of SQLITE_TEMP_STORE. The
+** following table describes the relationship between these two values
+** and this functions return value.
+**
+**   SQLITE_TEMP_STORE     db->temp_store     Location of temporary database
+**   -----------------     --------------     ------------------------------
+**   0                     any                file      (return 0)
+**   1                     1                  file      (return 0)
+**   1                     2                  memory    (return 1)
+**   1                     0                  file      (return 0)
+**   2                     1                  file      (return 0)
+**   2                     2                  memory    (return 1)
+**   2                     0                  memory    (return 1)
+**   3                     any                memory    (return 1)
+*/
+SQLITE_PRIVATE int sqlite3TempInMemory(const sqlite3 *db){
+#if SQLITE_TEMP_STORE==1
+  return ( db->temp_store==2 );
+#endif
+#if SQLITE_TEMP_STORE==2
+  return ( db->temp_store!=1 );
+#endif
+#if SQLITE_TEMP_STORE==3
+  UNUSED_PARAMETER(db);
+  return 1;
+#endif
+#if SQLITE_TEMP_STORE<1 || SQLITE_TEMP_STORE>3
+  UNUSED_PARAMETER(db);
+  return 0;
+#endif
+}
+
+/*
+** Return UTF-8 encoded English language explanation of the most recent
+** error.
+*/
+SQLITE_API const char *sqlite3_errmsg(sqlite3 *db){
+  const char *z;
+  if( !db ){
+    return sqlite3ErrStr(SQLITE_NOMEM_BKPT);
+  }
+  if( !sqlite3SafetyCheckSickOrOk(db) ){
+    return sqlite3ErrStr(SQLITE_MISUSE_BKPT);
+  }
+  sqlite3_mutex_enter(db->mutex);
+  if( db->mallocFailed ){
+    z = sqlite3ErrStr(SQLITE_NOMEM_BKPT);
+  }else{
+    testcase( db->pErr==0 );
+    z = (char*)sqlite3_value_text(db->pErr);
+    assert( !db->mallocFailed );
+    if( z==0 ){
+      z = sqlite3ErrStr(db->errCode);
+    }
+  }
+  sqlite3_mutex_leave(db->mutex);
+  return z;
+}
+
+#ifndef SQLITE_OMIT_UTF16
+/*
+** Return UTF-16 encoded English language explanation of the most recent
+** error.
+*/
+SQLITE_API const void *sqlite3_errmsg16(sqlite3 *db){
+  static const u16 outOfMem[] = {
+    'o', 'u', 't', ' ', 'o', 'f', ' ', 'm', 'e', 'm', 'o', 'r', 'y', 0
+  };
+  static const u16 misuse[] = {
+    'l', 'i', 'b', 'r', 'a', 'r', 'y', ' ', 
+    'r', 'o', 'u', 't', 'i', 'n', 'e', ' ', 
+    'c', 'a', 'l', 'l', 'e', 'd', ' ', 
+    'o', 'u', 't', ' ', 
+    'o', 'f', ' ', 
+    's', 'e', 'q', 'u', 'e', 'n', 'c', 'e', 0
+  };
+
+  const void *z;
+  if( !db ){
+    return (void *)outOfMem;
+  }
+  if( !sqlite3SafetyCheckSickOrOk(db) ){
+    return (void *)misuse;
+  }
+  sqlite3_mutex_enter(db->mutex);
+  if( db->mallocFailed ){
+    z = (void *)outOfMem;
+  }else{
+    z = sqlite3_value_text16(db->pErr);
+    if( z==0 ){
+      sqlite3ErrorWithMsg(db, db->errCode, sqlite3ErrStr(db->errCode));
+      z = sqlite3_value_text16(db->pErr);
+    }
+    /* A malloc() may have failed within the call to sqlite3_value_text16()
+    ** above. If this is the case, then the db->mallocFailed flag needs to
+    ** be cleared before returning. Do this directly, instead of via
+    ** sqlite3ApiExit(), to avoid setting the database handle error message.
+    */
+    sqlite3OomClear(db);
+  }
+  sqlite3_mutex_leave(db->mutex);
+  return z;
+}
+#endif /* SQLITE_OMIT_UTF16 */
+
+/*
+** Return the most recent error code generated by an SQLite routine. If NULL is
+** passed to this function, we assume a malloc() failed during sqlite3_open().
+*/
+SQLITE_API int sqlite3_errcode(sqlite3 *db){
+  if( db && !sqlite3SafetyCheckSickOrOk(db) ){
+    return SQLITE_MISUSE_BKPT;
+  }
+  if( !db || db->mallocFailed ){
+    return SQLITE_NOMEM_BKPT;
+  }
+  return db->errCode & db->errMask;
+}
+SQLITE_API int sqlite3_extended_errcode(sqlite3 *db){
+  if( db && !sqlite3SafetyCheckSickOrOk(db) ){
+    return SQLITE_MISUSE_BKPT;
+  }
+  if( !db || db->mallocFailed ){
+    return SQLITE_NOMEM_BKPT;
+  }
+  return db->errCode;
+}
+SQLITE_API int sqlite3_system_errno(sqlite3 *db){
+  return db ? db->iSysErrno : 0;
+}  
+
+/*
+** Return a string that describes the kind of error specified in the
+** argument.  For now, this simply calls the internal sqlite3ErrStr()
+** function.
+*/
+SQLITE_API const char *sqlite3_errstr(int rc){
+  return sqlite3ErrStr(rc);
+}
+
+/*
+** Create a new collating function for database "db".  The name is zName
+** and the encoding is enc.
+*/
+static int createCollation(
+  sqlite3* db,
+  const char *zName, 
+  u8 enc,
+  void* pCtx,
+  int(*xCompare)(void*,int,const void*,int,const void*),
+  void(*xDel)(void*)
+){
+  CollSeq *pColl;
+  int enc2;
+  
+  assert( sqlite3_mutex_held(db->mutex) );
+
+  /* If SQLITE_UTF16 is specified as the encoding type, transform this
+  ** to one of SQLITE_UTF16LE or SQLITE_UTF16BE using the
+  ** SQLITE_UTF16NATIVE macro. SQLITE_UTF16 is not used internally.
+  */
+  enc2 = enc;
+  testcase( enc2==SQLITE_UTF16 );
+  testcase( enc2==SQLITE_UTF16_ALIGNED );
+  if( enc2==SQLITE_UTF16 || enc2==SQLITE_UTF16_ALIGNED ){
+    enc2 = SQLITE_UTF16NATIVE;
+  }
+  if( enc2<SQLITE_UTF8 || enc2>SQLITE_UTF16BE ){
+    return SQLITE_MISUSE_BKPT;
+  }
+
+  /* Check if this call is removing or replacing an existing collation 
+  ** sequence. If so, and there are active VMs, return busy. If there
+  ** are no active VMs, invalidate any pre-compiled statements.
+  */
+  pColl = sqlite3FindCollSeq(db, (u8)enc2, zName, 0);
+  if( pColl && pColl->xCmp ){
+    if( db->nVdbeActive ){
+      sqlite3ErrorWithMsg(db, SQLITE_BUSY, 
+        "unable to delete/modify collation sequence due to active statements");
+      return SQLITE_BUSY;
+    }
+    sqlite3ExpirePreparedStatements(db);
+
+    /* If collation sequence pColl was created directly by a call to
+    ** sqlite3_create_collation, and not generated by synthCollSeq(),
+    ** then any copies made by synthCollSeq() need to be invalidated.
+    ** Also, collation destructor - CollSeq.xDel() - function may need
+    ** to be called.
+    */ 
+    if( (pColl->enc & ~SQLITE_UTF16_ALIGNED)==enc2 ){
+      CollSeq *aColl = sqlite3HashFind(&db->aCollSeq, zName);
+      int j;
+      for(j=0; j<3; j++){
+        CollSeq *p = &aColl[j];
+        if( p->enc==pColl->enc ){
+          if( p->xDel ){
+            p->xDel(p->pUser);
+          }
+          p->xCmp = 0;
+        }
+      }
+    }
+  }
+
+  pColl = sqlite3FindCollSeq(db, (u8)enc2, zName, 1);
+  if( pColl==0 ) return SQLITE_NOMEM_BKPT;
+  pColl->xCmp = xCompare;
+  pColl->pUser = pCtx;
+  pColl->xDel = xDel;
+  pColl->enc = (u8)(enc2 | (enc & SQLITE_UTF16_ALIGNED));
+  sqlite3Error(db, SQLITE_OK);
+  return SQLITE_OK;
+}
+
+
+/*
+** This array defines hard upper bounds on limit values.  The
+** initializer must be kept in sync with the SQLITE_LIMIT_*
+** #defines in sqlite3.h.
+*/
+static const int aHardLimit[] = {
+  SQLITE_MAX_LENGTH,
+  SQLITE_MAX_SQL_LENGTH,
+  SQLITE_MAX_COLUMN,
+  SQLITE_MAX_EXPR_DEPTH,
+  SQLITE_MAX_COMPOUND_SELECT,
+  SQLITE_MAX_VDBE_OP,
+  SQLITE_MAX_FUNCTION_ARG,
+  SQLITE_MAX_ATTACHED,
+  SQLITE_MAX_LIKE_PATTERN_LENGTH,
+  SQLITE_MAX_VARIABLE_NUMBER,      /* IMP: R-38091-32352 */
+  SQLITE_MAX_TRIGGER_DEPTH,
+  SQLITE_MAX_WORKER_THREADS,
+};
+
+/*
+** Make sure the hard limits are set to reasonable values
+*/
+#if SQLITE_MAX_LENGTH<100
+# error SQLITE_MAX_LENGTH must be at least 100
+#endif
+#if SQLITE_MAX_SQL_LENGTH<100
+# error SQLITE_MAX_SQL_LENGTH must be at least 100
+#endif
+#if SQLITE_MAX_SQL_LENGTH>SQLITE_MAX_LENGTH
+# error SQLITE_MAX_SQL_LENGTH must not be greater than SQLITE_MAX_LENGTH
+#endif
+#if SQLITE_MAX_COMPOUND_SELECT<2
+# error SQLITE_MAX_COMPOUND_SELECT must be at least 2
+#endif
+#if SQLITE_MAX_VDBE_OP<40
+# error SQLITE_MAX_VDBE_OP must be at least 40
+#endif
+#if SQLITE_MAX_FUNCTION_ARG<0 || SQLITE_MAX_FUNCTION_ARG>127
+# error SQLITE_MAX_FUNCTION_ARG must be between 0 and 127
+#endif
+#if SQLITE_MAX_ATTACHED<0 || SQLITE_MAX_ATTACHED>125
+# error SQLITE_MAX_ATTACHED must be between 0 and 125
+#endif
+#if SQLITE_MAX_LIKE_PATTERN_LENGTH<1
+# error SQLITE_MAX_LIKE_PATTERN_LENGTH must be at least 1
+#endif
+#if SQLITE_MAX_COLUMN>32767
+# error SQLITE_MAX_COLUMN must not exceed 32767
+#endif
+#if SQLITE_MAX_TRIGGER_DEPTH<1
+# error SQLITE_MAX_TRIGGER_DEPTH must be at least 1
+#endif
+#if SQLITE_MAX_WORKER_THREADS<0 || SQLITE_MAX_WORKER_THREADS>50
+# error SQLITE_MAX_WORKER_THREADS must be between 0 and 50
+#endif
+
+
+/*
+** Change the value of a limit.  Report the old value.
+** If an invalid limit index is supplied, report -1.
+** Make no changes but still report the old value if the
+** new limit is negative.
+**
+** A new lower limit does not shrink existing constructs.
+** It merely prevents new constructs that exceed the limit
+** from forming.
+*/
+SQLITE_API int sqlite3_limit(sqlite3 *db, int limitId, int newLimit){
+  int oldLimit;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return -1;
+  }
+#endif
+
+  /* EVIDENCE-OF: R-30189-54097 For each limit category SQLITE_LIMIT_NAME
+  ** there is a hard upper bound set at compile-time by a C preprocessor
+  ** macro called SQLITE_MAX_NAME. (The "_LIMIT_" in the name is changed to
+  ** "_MAX_".)
+  */
+  assert( aHardLimit[SQLITE_LIMIT_LENGTH]==SQLITE_MAX_LENGTH );
+  assert( aHardLimit[SQLITE_LIMIT_SQL_LENGTH]==SQLITE_MAX_SQL_LENGTH );
+  assert( aHardLimit[SQLITE_LIMIT_COLUMN]==SQLITE_MAX_COLUMN );
+  assert( aHardLimit[SQLITE_LIMIT_EXPR_DEPTH]==SQLITE_MAX_EXPR_DEPTH );
+  assert( aHardLimit[SQLITE_LIMIT_COMPOUND_SELECT]==SQLITE_MAX_COMPOUND_SELECT);
+  assert( aHardLimit[SQLITE_LIMIT_VDBE_OP]==SQLITE_MAX_VDBE_OP );
+  assert( aHardLimit[SQLITE_LIMIT_FUNCTION_ARG]==SQLITE_MAX_FUNCTION_ARG );
+  assert( aHardLimit[SQLITE_LIMIT_ATTACHED]==SQLITE_MAX_ATTACHED );
+  assert( aHardLimit[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]==
+                                               SQLITE_MAX_LIKE_PATTERN_LENGTH );
+  assert( aHardLimit[SQLITE_LIMIT_VARIABLE_NUMBER]==SQLITE_MAX_VARIABLE_NUMBER);
+  assert( aHardLimit[SQLITE_LIMIT_TRIGGER_DEPTH]==SQLITE_MAX_TRIGGER_DEPTH );
+  assert( aHardLimit[SQLITE_LIMIT_WORKER_THREADS]==SQLITE_MAX_WORKER_THREADS );
+  assert( SQLITE_LIMIT_WORKER_THREADS==(SQLITE_N_LIMIT-1) );
+
+
+  if( limitId<0 || limitId>=SQLITE_N_LIMIT ){
+    return -1;
+  }
+  oldLimit = db->aLimit[limitId];
+  if( newLimit>=0 ){                   /* IMP: R-52476-28732 */
+    if( newLimit>aHardLimit[limitId] ){
+      newLimit = aHardLimit[limitId];  /* IMP: R-51463-25634 */
+    }
+    db->aLimit[limitId] = newLimit;
+  }
+  return oldLimit;                     /* IMP: R-53341-35419 */
+}
+
+/*
+** This function is used to parse both URIs and non-URI filenames passed by the
+** user to API functions sqlite3_open() or sqlite3_open_v2(), and for database
+** URIs specified as part of ATTACH statements.
+**
+** The first argument to this function is the name of the VFS to use (or
+** a NULL to signify the default VFS) if the URI does not contain a "vfs=xxx"
+** query parameter. The second argument contains the URI (or non-URI filename)
+** itself. When this function is called the *pFlags variable should contain
+** the default flags to open the database handle with. The value stored in
+** *pFlags may be updated before returning if the URI filename contains 
+** "cache=xxx" or "mode=xxx" query parameters.
+**
+** If successful, SQLITE_OK is returned. In this case *ppVfs is set to point to
+** the VFS that should be used to open the database file. *pzFile is set to
+** point to a buffer containing the name of the file to open. It is the 
+** responsibility of the caller to eventually call sqlite3_free() to release
+** this buffer.
+**
+** If an error occurs, then an SQLite error code is returned and *pzErrMsg
+** may be set to point to a buffer containing an English language error 
+** message. It is the responsibility of the caller to eventually release
+** this buffer by calling sqlite3_free().
+*/
+SQLITE_PRIVATE int sqlite3ParseUri(
+  const char *zDefaultVfs,        /* VFS to use if no "vfs=xxx" query option */
+  const char *zUri,               /* Nul-terminated URI to parse */
+  unsigned int *pFlags,           /* IN/OUT: SQLITE_OPEN_XXX flags */
+  sqlite3_vfs **ppVfs,            /* OUT: VFS to use */ 
+  char **pzFile,                  /* OUT: Filename component of URI */
+  char **pzErrMsg                 /* OUT: Error message (if rc!=SQLITE_OK) */
+){
+  int rc = SQLITE_OK;
+  unsigned int flags = *pFlags;
+  const char *zVfs = zDefaultVfs;
+  char *zFile;
+  char c;
+  int nUri = sqlite3Strlen30(zUri);
+
+  assert( *pzErrMsg==0 );
+
+  if( ((flags & SQLITE_OPEN_URI)             /* IMP: R-48725-32206 */
+            || sqlite3GlobalConfig.bOpenUri) /* IMP: R-51689-46548 */
+   && nUri>=5 && memcmp(zUri, "file:", 5)==0 /* IMP: R-57884-37496 */
+  ){
+    char *zOpt;
+    int eState;                   /* Parser state when parsing URI */
+    int iIn;                      /* Input character index */
+    int iOut = 0;                 /* Output character index */
+    u64 nByte = nUri+2;           /* Bytes of space to allocate */
+
+    /* Make sure the SQLITE_OPEN_URI flag is set to indicate to the VFS xOpen 
+    ** method that there may be extra parameters following the file-name.  */
+    flags |= SQLITE_OPEN_URI;
+
+    for(iIn=0; iIn<nUri; iIn++) nByte += (zUri[iIn]=='&');
+    zFile = sqlite3_malloc64(nByte);
+    if( !zFile ) return SQLITE_NOMEM_BKPT;
+
+    iIn = 5;
+#ifdef SQLITE_ALLOW_URI_AUTHORITY
+    if( strncmp(zUri+5, "///", 3)==0 ){
+      iIn = 7;
+      /* The following condition causes URIs with five leading / characters
+      ** like file://///host/path to be converted into UNCs like //host/path.
+      ** The correct URI for that UNC has only two or four leading / characters
+      ** file://host/path or file:////host/path.  But 5 leading slashes is a 
+      ** common error, we are told, so we handle it as a special case. */
+      if( strncmp(zUri+7, "///", 3)==0 ){ iIn++; }
+    }else if( strncmp(zUri+5, "//localhost/", 12)==0 ){
+      iIn = 16;
+    }
+#else
+    /* Discard the scheme and authority segments of the URI. */
+    if( zUri[5]=='/' && zUri[6]=='/' ){
+      iIn = 7;
+      while( zUri[iIn] && zUri[iIn]!='/' ) iIn++;
+      if( iIn!=7 && (iIn!=16 || memcmp("localhost", &zUri[7], 9)) ){
+        *pzErrMsg = sqlite3_mprintf("invalid uri authority: %.*s", 
+            iIn-7, &zUri[7]);
+        rc = SQLITE_ERROR;
+        goto parse_uri_out;
+      }
+    }
+#endif
+
+    /* Copy the filename and any query parameters into the zFile buffer. 
+    ** Decode %HH escape codes along the way. 
+    **
+    ** Within this loop, variable eState may be set to 0, 1 or 2, depending
+    ** on the parsing context. As follows:
+    **
+    **   0: Parsing file-name.
+    **   1: Parsing name section of a name=value query parameter.
+    **   2: Parsing value section of a name=value query parameter.
+    */
+    eState = 0;
+    while( (c = zUri[iIn])!=0 && c!='#' ){
+      iIn++;
+      if( c=='%' 
+       && sqlite3Isxdigit(zUri[iIn]) 
+       && sqlite3Isxdigit(zUri[iIn+1]) 
+      ){
+        int octet = (sqlite3HexToInt(zUri[iIn++]) << 4);
+        octet += sqlite3HexToInt(zUri[iIn++]);
+
+        assert( octet>=0 && octet<256 );
+        if( octet==0 ){
+          /* This branch is taken when "%00" appears within the URI. In this
+          ** case we ignore all text in the remainder of the path, name or
+          ** value currently being parsed. So ignore the current character
+          ** and skip to the next "?", "=" or "&", as appropriate. */
+          while( (c = zUri[iIn])!=0 && c!='#' 
+              && (eState!=0 || c!='?')
+              && (eState!=1 || (c!='=' && c!='&'))
+              && (eState!=2 || c!='&')
+          ){
+            iIn++;
+          }
+          continue;
+        }
+        c = octet;
+      }else if( eState==1 && (c=='&' || c=='=') ){
+        if( zFile[iOut-1]==0 ){
+          /* An empty option name. Ignore this option altogether. */
+          while( zUri[iIn] && zUri[iIn]!='#' && zUri[iIn-1]!='&' ) iIn++;
+          continue;
+        }
+        if( c=='&' ){
+          zFile[iOut++] = '\0';
+        }else{
+          eState = 2;
+        }
+        c = 0;
+      }else if( (eState==0 && c=='?') || (eState==2 && c=='&') ){
+        c = 0;
+        eState = 1;
+      }
+      zFile[iOut++] = c;
+    }
+    if( eState==1 ) zFile[iOut++] = '\0';
+    zFile[iOut++] = '\0';
+    zFile[iOut++] = '\0';
+
+    /* Check if there were any options specified that should be interpreted 
+    ** here. Options that are interpreted here include "vfs" and those that
+    ** correspond to flags that may be passed to the sqlite3_open_v2()
+    ** method. */
+    zOpt = &zFile[sqlite3Strlen30(zFile)+1];
+    while( zOpt[0] ){
+      int nOpt = sqlite3Strlen30(zOpt);
+      char *zVal = &zOpt[nOpt+1];
+      int nVal = sqlite3Strlen30(zVal);
+
+      if( nOpt==3 && memcmp("vfs", zOpt, 3)==0 ){
+        zVfs = zVal;
+      }else{
+        struct OpenMode {
+          const char *z;
+          int mode;
+        } *aMode = 0;
+        char *zModeType = 0;
+        int mask = 0;
+        int limit = 0;
+
+        if( nOpt==5 && memcmp("cache", zOpt, 5)==0 ){
+          static struct OpenMode aCacheMode[] = {
+            { "shared",  SQLITE_OPEN_SHAREDCACHE },
+            { "private", SQLITE_OPEN_PRIVATECACHE },
+            { 0, 0 }
+          };
+
+          mask = SQLITE_OPEN_SHAREDCACHE|SQLITE_OPEN_PRIVATECACHE;
+          aMode = aCacheMode;
+          limit = mask;
+          zModeType = "cache";
+        }
+        if( nOpt==4 && memcmp("mode", zOpt, 4)==0 ){
+          static struct OpenMode aOpenMode[] = {
+            { "ro",  SQLITE_OPEN_READONLY },
+            { "rw",  SQLITE_OPEN_READWRITE }, 
+            { "rwc", SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE },
+            { "memory", SQLITE_OPEN_MEMORY },
+            { 0, 0 }
+          };
+
+          mask = SQLITE_OPEN_READONLY | SQLITE_OPEN_READWRITE
+                   | SQLITE_OPEN_CREATE | SQLITE_OPEN_MEMORY;
+          aMode = aOpenMode;
+          limit = mask & flags;
+          zModeType = "access";
+        }
+
+        if( aMode ){
+          int i;
+          int mode = 0;
+          for(i=0; aMode[i].z; i++){
+            const char *z = aMode[i].z;
+            if( nVal==sqlite3Strlen30(z) && 0==memcmp(zVal, z, nVal) ){
+              mode = aMode[i].mode;
+              break;
+            }
+          }
+          if( mode==0 ){
+            *pzErrMsg = sqlite3_mprintf("no such %s mode: %s", zModeType, zVal);
+            rc = SQLITE_ERROR;
+            goto parse_uri_out;
+          }
+          if( (mode & ~SQLITE_OPEN_MEMORY)>limit ){
+            *pzErrMsg = sqlite3_mprintf("%s mode not allowed: %s",
+                                        zModeType, zVal);
+            rc = SQLITE_PERM;
+            goto parse_uri_out;
+          }
+          flags = (flags & ~mask) | mode;
+        }
+      }
+
+      zOpt = &zVal[nVal+1];
+    }
+
+  }else{
+    zFile = sqlite3_malloc64(nUri+2);
+    if( !zFile ) return SQLITE_NOMEM_BKPT;
+    memcpy(zFile, zUri, nUri);
+    zFile[nUri] = '\0';
+    zFile[nUri+1] = '\0';
+    flags &= ~SQLITE_OPEN_URI;
+  }
+
+  *ppVfs = sqlite3_vfs_find(zVfs);
+  if( *ppVfs==0 ){
+    *pzErrMsg = sqlite3_mprintf("no such vfs: %s", zVfs);
+    rc = SQLITE_ERROR;
+  }
+ parse_uri_out:
+  if( rc!=SQLITE_OK ){
+    sqlite3_free(zFile);
+    zFile = 0;
+  }
+  *pFlags = flags;
+  *pzFile = zFile;
+  return rc;
+}
+
+
+/*
+** This routine does the work of opening a database on behalf of
+** sqlite3_open() and sqlite3_open16(). The database filename "zFilename"  
+** is UTF-8 encoded.
+*/
+static int openDatabase(
+  const char *zFilename, /* Database filename UTF-8 encoded */
+  sqlite3 **ppDb,        /* OUT: Returned database handle */
+  unsigned int flags,    /* Operational flags */
+  const char *zVfs       /* Name of the VFS to use */
+){
+  sqlite3 *db;                    /* Store allocated handle here */
+  int rc;                         /* Return code */
+  int isThreadsafe;               /* True for threadsafe connections */
+  char *zOpen = 0;                /* Filename argument to pass to BtreeOpen() */
+  char *zErrMsg = 0;              /* Error message from sqlite3ParseUri() */
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( ppDb==0 ) return SQLITE_MISUSE_BKPT;
+#endif
+  *ppDb = 0;
+#ifndef SQLITE_OMIT_AUTOINIT
+  rc = sqlite3_initialize();
+  if( rc ) return rc;
+#endif
+
+  /* Only allow sensible combinations of bits in the flags argument.  
+  ** Throw an error if any non-sense combination is used.  If we
+  ** do not block illegal combinations here, it could trigger
+  ** assert() statements in deeper layers.  Sensible combinations
+  ** are:
+  **
+  **  1:  SQLITE_OPEN_READONLY
+  **  2:  SQLITE_OPEN_READWRITE
+  **  6:  SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE
+  */
+  assert( SQLITE_OPEN_READONLY  == 0x01 );
+  assert( SQLITE_OPEN_READWRITE == 0x02 );
+  assert( SQLITE_OPEN_CREATE    == 0x04 );
+  testcase( (1<<(flags&7))==0x02 ); /* READONLY */
+  testcase( (1<<(flags&7))==0x04 ); /* READWRITE */
+  testcase( (1<<(flags&7))==0x40 ); /* READWRITE | CREATE */
+  if( ((1<<(flags&7)) & 0x46)==0 ){
+    return SQLITE_MISUSE_BKPT;  /* IMP: R-65497-44594 */
+  }
+
+  if( sqlite3GlobalConfig.bCoreMutex==0 ){
+    isThreadsafe = 0;
+  }else if( flags & SQLITE_OPEN_NOMUTEX ){
+    isThreadsafe = 0;
+  }else if( flags & SQLITE_OPEN_FULLMUTEX ){
+    isThreadsafe = 1;
+  }else{
+    isThreadsafe = sqlite3GlobalConfig.bFullMutex;
+  }
+  if( flags & SQLITE_OPEN_PRIVATECACHE ){
+    flags &= ~SQLITE_OPEN_SHAREDCACHE;
+  }else if( sqlite3GlobalConfig.sharedCacheEnabled ){
+    flags |= SQLITE_OPEN_SHAREDCACHE;
+  }
+
+  /* Remove harmful bits from the flags parameter
+  **
+  ** The SQLITE_OPEN_NOMUTEX and SQLITE_OPEN_FULLMUTEX flags were
+  ** dealt with in the previous code block.  Besides these, the only
+  ** valid input flags for sqlite3_open_v2() are SQLITE_OPEN_READONLY,
+  ** SQLITE_OPEN_READWRITE, SQLITE_OPEN_CREATE, SQLITE_OPEN_SHAREDCACHE,
+  ** SQLITE_OPEN_PRIVATECACHE, and some reserved bits.  Silently mask
+  ** off all other flags.
+  */
+  flags &=  ~( SQLITE_OPEN_DELETEONCLOSE |
+               SQLITE_OPEN_EXCLUSIVE |
+               SQLITE_OPEN_MAIN_DB |
+               SQLITE_OPEN_TEMP_DB | 
+               SQLITE_OPEN_TRANSIENT_DB | 
+               SQLITE_OPEN_MAIN_JOURNAL | 
+               SQLITE_OPEN_TEMP_JOURNAL | 
+               SQLITE_OPEN_SUBJOURNAL | 
+               SQLITE_OPEN_MASTER_JOURNAL |
+               SQLITE_OPEN_NOMUTEX |
+               SQLITE_OPEN_FULLMUTEX |
+               SQLITE_OPEN_WAL
+             );
+
+  /* Allocate the sqlite data structure */
+  db = sqlite3MallocZero( sizeof(sqlite3) );
+  if( db==0 ) goto opendb_out;
+  if( isThreadsafe ){
+    db->mutex = sqlite3MutexAlloc(SQLITE_MUTEX_RECURSIVE);
+    if( db->mutex==0 ){
+      sqlite3_free(db);
+      db = 0;
+      goto opendb_out;
+    }
+  }
+  sqlite3_mutex_enter(db->mutex);
+  db->errMask = 0xff;
+  db->nDb = 2;
+  db->magic = SQLITE_MAGIC_BUSY;
+  db->aDb = db->aDbStatic;
+
+  assert( sizeof(db->aLimit)==sizeof(aHardLimit) );
+  memcpy(db->aLimit, aHardLimit, sizeof(db->aLimit));
+  db->aLimit[SQLITE_LIMIT_WORKER_THREADS] = SQLITE_DEFAULT_WORKER_THREADS;
+  db->autoCommit = 1;
+  db->nextAutovac = -1;
+  db->szMmap = sqlite3GlobalConfig.szMmap;
+  db->nextPagesize = 0;
+  db->nMaxSorterMmap = 0x7FFFFFFF;
+  db->flags |= SQLITE_ShortColNames | SQLITE_EnableTrigger | SQLITE_CacheSpill
+#if !defined(SQLITE_DEFAULT_AUTOMATIC_INDEX) || SQLITE_DEFAULT_AUTOMATIC_INDEX
+                 | SQLITE_AutoIndex
+#endif
+#if SQLITE_DEFAULT_CKPTFULLFSYNC
+                 | SQLITE_CkptFullFSync
+#endif
+#if SQLITE_DEFAULT_FILE_FORMAT<4
+                 | SQLITE_LegacyFileFmt
+#endif
+#ifdef SQLITE_ENABLE_LOAD_EXTENSION
+                 | SQLITE_LoadExtension
+#endif
+#if SQLITE_DEFAULT_RECURSIVE_TRIGGERS
+                 | SQLITE_RecTriggers
+#endif
+#if defined(SQLITE_DEFAULT_FOREIGN_KEYS) && SQLITE_DEFAULT_FOREIGN_KEYS
+                 | SQLITE_ForeignKeys
+#endif
+#if defined(SQLITE_REVERSE_UNORDERED_SELECTS)
+                 | SQLITE_ReverseOrder
+#endif
+#if defined(SQLITE_ENABLE_OVERSIZE_CELL_CHECK)
+                 | SQLITE_CellSizeCk
+#endif
+#if defined(SQLITE_ENABLE_FTS3_TOKENIZER)
+                 | SQLITE_Fts3Tokenizer
+#endif
+      ;
+  sqlite3HashInit(&db->aCollSeq);
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  sqlite3HashInit(&db->aModule);
+#endif
+
+  /* Add the default collation sequence BINARY. BINARY works for both UTF-8
+  ** and UTF-16, so add a version for each to avoid any unnecessary
+  ** conversions. The only error that can occur here is a malloc() failure.
+  **
+  ** EVIDENCE-OF: R-52786-44878 SQLite defines three built-in collating
+  ** functions:
+  */
+  createCollation(db, sqlite3StrBINARY, SQLITE_UTF8, 0, binCollFunc, 0);
+  createCollation(db, sqlite3StrBINARY, SQLITE_UTF16BE, 0, binCollFunc, 0);
+  createCollation(db, sqlite3StrBINARY, SQLITE_UTF16LE, 0, binCollFunc, 0);
+  createCollation(db, "NOCASE", SQLITE_UTF8, 0, nocaseCollatingFunc, 0);
+  createCollation(db, "RTRIM", SQLITE_UTF8, (void*)1, binCollFunc, 0);
+  if( db->mallocFailed ){
+    goto opendb_out;
+  }
+  /* EVIDENCE-OF: R-08308-17224 The default collating function for all
+  ** strings is BINARY. 
+  */
+  db->pDfltColl = sqlite3FindCollSeq(db, SQLITE_UTF8, sqlite3StrBINARY, 0);
+  assert( db->pDfltColl!=0 );
+
+  /* Parse the filename/URI argument. */
+  db->openFlags = flags;
+  rc = sqlite3ParseUri(zVfs, zFilename, &flags, &db->pVfs, &zOpen, &zErrMsg);
+  if( rc!=SQLITE_OK ){
+    if( rc==SQLITE_NOMEM ) sqlite3OomFault(db);
+    sqlite3ErrorWithMsg(db, rc, zErrMsg ? "%s" : 0, zErrMsg);
+    sqlite3_free(zErrMsg);
+    goto opendb_out;
+  }
+
+  /* Open the backend database driver */
+  rc = sqlite3BtreeOpen(db->pVfs, zOpen, db, &db->aDb[0].pBt, 0,
+                        flags | SQLITE_OPEN_MAIN_DB);
+  if( rc!=SQLITE_OK ){
+    if( rc==SQLITE_IOERR_NOMEM ){
+      rc = SQLITE_NOMEM_BKPT;
+    }
+    sqlite3Error(db, rc);
+    goto opendb_out;
+  }
+  sqlite3BtreeEnter(db->aDb[0].pBt);
+  db->aDb[0].pSchema = sqlite3SchemaGet(db, db->aDb[0].pBt);
+  if( !db->mallocFailed ) ENC(db) = SCHEMA_ENC(db);
+  sqlite3BtreeLeave(db->aDb[0].pBt);
+  db->aDb[1].pSchema = sqlite3SchemaGet(db, 0);
+
+  /* The default safety_level for the main database is FULL; for the temp
+  ** database it is OFF. This matches the pager layer defaults.  
+  */
+  db->aDb[0].zDbSName = "main";
+  db->aDb[0].safety_level = SQLITE_DEFAULT_SYNCHRONOUS+1;
+  db->aDb[1].zDbSName = "temp";
+  db->aDb[1].safety_level = PAGER_SYNCHRONOUS_OFF;
+
+  db->magic = SQLITE_MAGIC_OPEN;
+  if( db->mallocFailed ){
+    goto opendb_out;
+  }
+
+  /* Register all built-in functions, but do not attempt to read the
+  ** database schema yet. This is delayed until the first time the database
+  ** is accessed.
+  */
+  sqlite3Error(db, SQLITE_OK);
+  sqlite3RegisterPerConnectionBuiltinFunctions(db);
+  rc = sqlite3_errcode(db);
+
+#ifdef SQLITE_ENABLE_FTS5
+  /* Register any built-in FTS5 module before loading the automatic
+  ** extensions. This allows automatic extensions to register FTS5 
+  ** tokenizers and auxiliary functions.  */
+  if( !db->mallocFailed && rc==SQLITE_OK ){
+    rc = sqlite3Fts5Init(db);
+  }
+#endif
+
+  /* Load automatic extensions - extensions that have been registered
+  ** using the sqlite3_automatic_extension() API.
+  */
+  if( rc==SQLITE_OK ){
+    sqlite3AutoLoadExtensions(db);
+    rc = sqlite3_errcode(db);
+    if( rc!=SQLITE_OK ){
+      goto opendb_out;
+    }
+  }
+
+#ifdef SQLITE_ENABLE_FTS1
+  if( !db->mallocFailed ){
+    extern int sqlite3Fts1Init(sqlite3*);
+    rc = sqlite3Fts1Init(db);
+  }
+#endif
+
+#ifdef SQLITE_ENABLE_FTS2
+  if( !db->mallocFailed && rc==SQLITE_OK ){
+    extern int sqlite3Fts2Init(sqlite3*);
+    rc = sqlite3Fts2Init(db);
+  }
+#endif
+
+#ifdef SQLITE_ENABLE_FTS3 /* automatically defined by SQLITE_ENABLE_FTS4 */
+  if( !db->mallocFailed && rc==SQLITE_OK ){
+    rc = sqlite3Fts3Init(db);
+  }
+#endif
+
+#ifdef SQLITE_ENABLE_ICU
+  if( !db->mallocFailed && rc==SQLITE_OK ){
+    rc = sqlite3IcuInit(db);
+  }
+#endif
+
+#ifdef SQLITE_ENABLE_RTREE
+  if( !db->mallocFailed && rc==SQLITE_OK){
+    rc = sqlite3RtreeInit(db);
+  }
+#endif
+
+#ifdef SQLITE_ENABLE_DBSTAT_VTAB
+  if( !db->mallocFailed && rc==SQLITE_OK){
+    rc = sqlite3DbstatRegister(db);
+  }
+#endif
+
+#ifdef SQLITE_ENABLE_JSON1
+  if( !db->mallocFailed && rc==SQLITE_OK){
+    rc = sqlite3Json1Init(db);
+  }
+#endif
+
+  /* -DSQLITE_DEFAULT_LOCKING_MODE=1 makes EXCLUSIVE the default locking
+  ** mode.  -DSQLITE_DEFAULT_LOCKING_MODE=0 make NORMAL the default locking
+  ** mode.  Doing nothing at all also makes NORMAL the default.
+  */
+#ifdef SQLITE_DEFAULT_LOCKING_MODE
+  db->dfltLockMode = SQLITE_DEFAULT_LOCKING_MODE;
+  sqlite3PagerLockingMode(sqlite3BtreePager(db->aDb[0].pBt),
+                          SQLITE_DEFAULT_LOCKING_MODE);
+#endif
+
+  if( rc ) sqlite3Error(db, rc);
+
+  /* Enable the lookaside-malloc subsystem */
+  setupLookaside(db, 0, sqlite3GlobalConfig.szLookaside,
+                        sqlite3GlobalConfig.nLookaside);
+
+  sqlite3_wal_autocheckpoint(db, SQLITE_DEFAULT_WAL_AUTOCHECKPOINT);
+
+opendb_out:
+  if( db ){
+    assert( db->mutex!=0 || isThreadsafe==0
+           || sqlite3GlobalConfig.bFullMutex==0 );
+    sqlite3_mutex_leave(db->mutex);
+  }
+  rc = sqlite3_errcode(db);
+  assert( db!=0 || rc==SQLITE_NOMEM );
+  if( rc==SQLITE_NOMEM ){
+    sqlite3_close(db);
+    db = 0;
+  }else if( rc!=SQLITE_OK ){
+    db->magic = SQLITE_MAGIC_SICK;
+  }
+  *ppDb = db;
+#ifdef SQLITE_ENABLE_SQLLOG
+  if( sqlite3GlobalConfig.xSqllog ){
+    /* Opening a db handle. Fourth parameter is passed 0. */
+    void *pArg = sqlite3GlobalConfig.pSqllogArg;
+    sqlite3GlobalConfig.xSqllog(pArg, db, zFilename, 0);
+  }
+#endif
+#if defined(SQLITE_HAS_CODEC)
+  if( rc==SQLITE_OK ){
+    const char *zHexKey = sqlite3_uri_parameter(zOpen, "hexkey");
+    if( zHexKey && zHexKey[0] ){
+      u8 iByte;
+      int i;
+      char zKey[40];
+      for(i=0, iByte=0; i<sizeof(zKey)*2 && sqlite3Isxdigit(zHexKey[i]); i++){
+        iByte = (iByte<<4) + sqlite3HexToInt(zHexKey[i]);
+        if( (i&1)!=0 ) zKey[i/2] = iByte;
+      }
+      sqlite3_key_v2(db, 0, zKey, i/2);
+    }
+  }
+#endif
+  sqlite3_free(zOpen);
+  return rc & 0xff;
+}
+
+/*
+** Open a new database handle.
+*/
+SQLITE_API int sqlite3_open(
+  const char *zFilename, 
+  sqlite3 **ppDb 
+){
+  return openDatabase(zFilename, ppDb,
+                      SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, 0);
+}
+SQLITE_API int sqlite3_open_v2(
+  const char *filename,   /* Database filename (UTF-8) */
+  sqlite3 **ppDb,         /* OUT: SQLite db handle */
+  int flags,              /* Flags */
+  const char *zVfs        /* Name of VFS module to use */
+){
+  return openDatabase(filename, ppDb, (unsigned int)flags, zVfs);
+}
+
+#ifndef SQLITE_OMIT_UTF16
+/*
+** Open a new database handle.
+*/
+SQLITE_API int sqlite3_open16(
+  const void *zFilename, 
+  sqlite3 **ppDb
+){
+  char const *zFilename8;   /* zFilename encoded in UTF-8 instead of UTF-16 */
+  sqlite3_value *pVal;
+  int rc;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( ppDb==0 ) return SQLITE_MISUSE_BKPT;
+#endif
+  *ppDb = 0;
+#ifndef SQLITE_OMIT_AUTOINIT
+  rc = sqlite3_initialize();
+  if( rc ) return rc;
+#endif
+  if( zFilename==0 ) zFilename = "\000\000";
+  pVal = sqlite3ValueNew(0);
+  sqlite3ValueSetStr(pVal, -1, zFilename, SQLITE_UTF16NATIVE, SQLITE_STATIC);
+  zFilename8 = sqlite3ValueText(pVal, SQLITE_UTF8);
+  if( zFilename8 ){
+    rc = openDatabase(zFilename8, ppDb,
+                      SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, 0);
+    assert( *ppDb || rc==SQLITE_NOMEM );
+    if( rc==SQLITE_OK && !DbHasProperty(*ppDb, 0, DB_SchemaLoaded) ){
+      SCHEMA_ENC(*ppDb) = ENC(*ppDb) = SQLITE_UTF16NATIVE;
+    }
+  }else{
+    rc = SQLITE_NOMEM_BKPT;
+  }
+  sqlite3ValueFree(pVal);
+
+  return rc & 0xff;
+}
+#endif /* SQLITE_OMIT_UTF16 */
+
+/*
+** Register a new collation sequence with the database handle db.
+*/
+SQLITE_API int sqlite3_create_collation(
+  sqlite3* db, 
+  const char *zName, 
+  int enc, 
+  void* pCtx,
+  int(*xCompare)(void*,int,const void*,int,const void*)
+){
+  return sqlite3_create_collation_v2(db, zName, enc, pCtx, xCompare, 0);
+}
+
+/*
+** Register a new collation sequence with the database handle db.
+*/
+SQLITE_API int sqlite3_create_collation_v2(
+  sqlite3* db, 
+  const char *zName, 
+  int enc, 
+  void* pCtx,
+  int(*xCompare)(void*,int,const void*,int,const void*),
+  void(*xDel)(void*)
+){
+  int rc;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) || zName==0 ) return SQLITE_MISUSE_BKPT;
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  assert( !db->mallocFailed );
+  rc = createCollation(db, zName, (u8)enc, pCtx, xCompare, xDel);
+  rc = sqlite3ApiExit(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+#ifndef SQLITE_OMIT_UTF16
+/*
+** Register a new collation sequence with the database handle db.
+*/
+SQLITE_API int sqlite3_create_collation16(
+  sqlite3* db, 
+  const void *zName,
+  int enc, 
+  void* pCtx,
+  int(*xCompare)(void*,int,const void*,int,const void*)
+){
+  int rc = SQLITE_OK;
+  char *zName8;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) || zName==0 ) return SQLITE_MISUSE_BKPT;
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  assert( !db->mallocFailed );
+  zName8 = sqlite3Utf16to8(db, zName, -1, SQLITE_UTF16NATIVE);
+  if( zName8 ){
+    rc = createCollation(db, zName8, (u8)enc, pCtx, xCompare, 0);
+    sqlite3DbFree(db, zName8);
+  }
+  rc = sqlite3ApiExit(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+#endif /* SQLITE_OMIT_UTF16 */
+
+/*
+** Register a collation sequence factory callback with the database handle
+** db. Replace any previously installed collation sequence factory.
+*/
+SQLITE_API int sqlite3_collation_needed(
+  sqlite3 *db, 
+  void *pCollNeededArg, 
+  void(*xCollNeeded)(void*,sqlite3*,int eTextRep,const char*)
+){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  db->xCollNeeded = xCollNeeded;
+  db->xCollNeeded16 = 0;
+  db->pCollNeededArg = pCollNeededArg;
+  sqlite3_mutex_leave(db->mutex);
+  return SQLITE_OK;
+}
+
+#ifndef SQLITE_OMIT_UTF16
+/*
+** Register a collation sequence factory callback with the database handle
+** db. Replace any previously installed collation sequence factory.
+*/
+SQLITE_API int sqlite3_collation_needed16(
+  sqlite3 *db, 
+  void *pCollNeededArg, 
+  void(*xCollNeeded16)(void*,sqlite3*,int eTextRep,const void*)
+){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  db->xCollNeeded = 0;
+  db->xCollNeeded16 = xCollNeeded16;
+  db->pCollNeededArg = pCollNeededArg;
+  sqlite3_mutex_leave(db->mutex);
+  return SQLITE_OK;
+}
+#endif /* SQLITE_OMIT_UTF16 */
+
+#ifndef SQLITE_OMIT_DEPRECATED
+/*
+** This function is now an anachronism. It used to be used to recover from a
+** malloc() failure, but SQLite now does this automatically.
+*/
+SQLITE_API int sqlite3_global_recover(void){
+  return SQLITE_OK;
+}
+#endif
+
+/*
+** Test to see whether or not the database connection is in autocommit
+** mode.  Return TRUE if it is and FALSE if not.  Autocommit mode is on
+** by default.  Autocommit is disabled by a BEGIN statement and reenabled
+** by the next COMMIT or ROLLBACK.
+*/
+SQLITE_API int sqlite3_get_autocommit(sqlite3 *db){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  return db->autoCommit;
+}
+
+/*
+** The following routines are substitutes for constants SQLITE_CORRUPT,
+** SQLITE_MISUSE, SQLITE_CANTOPEN, SQLITE_NOMEM and possibly other error
+** constants.  They serve two purposes:
+**
+**   1.  Serve as a convenient place to set a breakpoint in a debugger
+**       to detect when version error conditions occurs.
+**
+**   2.  Invoke sqlite3_log() to provide the source code location where
+**       a low-level error is first detected.
+*/
+static int reportError(int iErr, int lineno, const char *zType){
+  sqlite3_log(iErr, "%s at line %d of [%.10s]",
+              zType, lineno, 20+sqlite3_sourceid());
+  return iErr;
+}
+SQLITE_PRIVATE int sqlite3CorruptError(int lineno){
+  testcase( sqlite3GlobalConfig.xLog!=0 );
+  return reportError(SQLITE_CORRUPT, lineno, "database corruption");
+}
+SQLITE_PRIVATE int sqlite3MisuseError(int lineno){
+  testcase( sqlite3GlobalConfig.xLog!=0 );
+  return reportError(SQLITE_MISUSE, lineno, "misuse");
+}
+SQLITE_PRIVATE int sqlite3CantopenError(int lineno){
+  testcase( sqlite3GlobalConfig.xLog!=0 );
+  return reportError(SQLITE_CANTOPEN, lineno, "cannot open file");
+}
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE int sqlite3NomemError(int lineno){
+  testcase( sqlite3GlobalConfig.xLog!=0 );
+  return reportError(SQLITE_NOMEM, lineno, "OOM");
+}
+SQLITE_PRIVATE int sqlite3IoerrnomemError(int lineno){
+  testcase( sqlite3GlobalConfig.xLog!=0 );
+  return reportError(SQLITE_IOERR_NOMEM, lineno, "I/O OOM error");
+}
+#endif
+
+#ifndef SQLITE_OMIT_DEPRECATED
+/*
+** This is a convenience routine that makes sure that all thread-specific
+** data for this thread has been deallocated.
+**
+** SQLite no longer uses thread-specific data so this routine is now a
+** no-op.  It is retained for historical compatibility.
+*/
+SQLITE_API void sqlite3_thread_cleanup(void){
+}
+#endif
+
+/*
+** Return meta information about a specific column of a database table.
+** See comment in sqlite3.h (sqlite.h.in) for details.
+*/
+SQLITE_API int sqlite3_table_column_metadata(
+  sqlite3 *db,                /* Connection handle */
+  const char *zDbName,        /* Database name or NULL */
+  const char *zTableName,     /* Table name */
+  const char *zColumnName,    /* Column name */
+  char const **pzDataType,    /* OUTPUT: Declared data type */
+  char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
+  int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
+  int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
+  int *pAutoinc               /* OUTPUT: True if column is auto-increment */
+){
+  int rc;
+  char *zErrMsg = 0;
+  Table *pTab = 0;
+  Column *pCol = 0;
+  int iCol = 0;
+  char const *zDataType = 0;
+  char const *zCollSeq = 0;
+  int notnull = 0;
+  int primarykey = 0;
+  int autoinc = 0;
+
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) || zTableName==0 ){
+    return SQLITE_MISUSE_BKPT;
+  }
+#endif
+
+  /* Ensure the database schema has been loaded */
+  sqlite3_mutex_enter(db->mutex);
+  sqlite3BtreeEnterAll(db);
+  rc = sqlite3Init(db, &zErrMsg);
+  if( SQLITE_OK!=rc ){
+    goto error_out;
+  }
+
+  /* Locate the table in question */
+  pTab = sqlite3FindTable(db, zTableName, zDbName);
+  if( !pTab || pTab->pSelect ){
+    pTab = 0;
+    goto error_out;
+  }
+
+  /* Find the column for which info is requested */
+  if( zColumnName==0 ){
+    /* Query for existance of table only */
+  }else{
+    for(iCol=0; iCol<pTab->nCol; iCol++){
+      pCol = &pTab->aCol[iCol];
+      if( 0==sqlite3StrICmp(pCol->zName, zColumnName) ){
+        break;
+      }
+    }
+    if( iCol==pTab->nCol ){
+      if( HasRowid(pTab) && sqlite3IsRowid(zColumnName) ){
+        iCol = pTab->iPKey;
+        pCol = iCol>=0 ? &pTab->aCol[iCol] : 0;
+      }else{
+        pTab = 0;
+        goto error_out;
+      }
+    }
+  }
+
+  /* The following block stores the meta information that will be returned
+  ** to the caller in local variables zDataType, zCollSeq, notnull, primarykey
+  ** and autoinc. At this point there are two possibilities:
+  ** 
+  **     1. The specified column name was rowid", "oid" or "_rowid_" 
+  **        and there is no explicitly declared IPK column. 
+  **
+  **     2. The table is not a view and the column name identified an 
+  **        explicitly declared column. Copy meta information from *pCol.
+  */ 
+  if( pCol ){
+    zDataType = sqlite3ColumnType(pCol,0);
+    zCollSeq = pCol->zColl;
+    notnull = pCol->notNull!=0;
+    primarykey  = (pCol->colFlags & COLFLAG_PRIMKEY)!=0;
+    autoinc = pTab->iPKey==iCol && (pTab->tabFlags & TF_Autoincrement)!=0;
+  }else{
+    zDataType = "INTEGER";
+    primarykey = 1;
+  }
+  if( !zCollSeq ){
+    zCollSeq = sqlite3StrBINARY;
+  }
+
+error_out:
+  sqlite3BtreeLeaveAll(db);
+
+  /* Whether the function call succeeded or failed, set the output parameters
+  ** to whatever their local counterparts contain. If an error did occur,
+  ** this has the effect of zeroing all output parameters.
+  */
+  if( pzDataType ) *pzDataType = zDataType;
+  if( pzCollSeq ) *pzCollSeq = zCollSeq;
+  if( pNotNull ) *pNotNull = notnull;
+  if( pPrimaryKey ) *pPrimaryKey = primarykey;
+  if( pAutoinc ) *pAutoinc = autoinc;
+
+  if( SQLITE_OK==rc && !pTab ){
+    sqlite3DbFree(db, zErrMsg);
+    zErrMsg = sqlite3MPrintf(db, "no such table column: %s.%s", zTableName,
+        zColumnName);
+    rc = SQLITE_ERROR;
+  }
+  sqlite3ErrorWithMsg(db, rc, (zErrMsg?"%s":0), zErrMsg);
+  sqlite3DbFree(db, zErrMsg);
+  rc = sqlite3ApiExit(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+/*
+** Sleep for a little while.  Return the amount of time slept.
+*/
+SQLITE_API int sqlite3_sleep(int ms){
+  sqlite3_vfs *pVfs;
+  int rc;
+  pVfs = sqlite3_vfs_find(0);
+  if( pVfs==0 ) return 0;
+
+  /* This function works in milliseconds, but the underlying OsSleep() 
+  ** API uses microseconds. Hence the 1000's.
+  */
+  rc = (sqlite3OsSleep(pVfs, 1000*ms)/1000);
+  return rc;
+}
+
+/*
+** Enable or disable the extended result codes.
+*/
+SQLITE_API int sqlite3_extended_result_codes(sqlite3 *db, int onoff){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  db->errMask = onoff ? 0xffffffff : 0xff;
+  sqlite3_mutex_leave(db->mutex);
+  return SQLITE_OK;
+}
+
+/*
+** Invoke the xFileControl method on a particular database.
+*/
+SQLITE_API int sqlite3_file_control(sqlite3 *db, const char *zDbName, int op, void *pArg){
+  int rc = SQLITE_ERROR;
+  Btree *pBtree;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  pBtree = sqlite3DbNameToBtree(db, zDbName);
+  if( pBtree ){
+    Pager *pPager;
+    sqlite3_file *fd;
+    sqlite3BtreeEnter(pBtree);
+    pPager = sqlite3BtreePager(pBtree);
+    assert( pPager!=0 );
+    fd = sqlite3PagerFile(pPager);
+    assert( fd!=0 );
+    if( op==SQLITE_FCNTL_FILE_POINTER ){
+      *(sqlite3_file**)pArg = fd;
+      rc = SQLITE_OK;
+    }else if( op==SQLITE_FCNTL_VFS_POINTER ){
+      *(sqlite3_vfs**)pArg = sqlite3PagerVfs(pPager);
+      rc = SQLITE_OK;
+    }else if( op==SQLITE_FCNTL_JOURNAL_POINTER ){
+      *(sqlite3_file**)pArg = sqlite3PagerJrnlFile(pPager);
+      rc = SQLITE_OK;
+    }else if( fd->pMethods ){
+      rc = sqlite3OsFileControl(fd, op, pArg);
+    }else{
+      rc = SQLITE_NOTFOUND;
+    }
+    sqlite3BtreeLeave(pBtree);
+  }
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+/*
+** Interface to the testing logic.
+*/
+SQLITE_API int sqlite3_test_control(int op, ...){
+  int rc = 0;
+#ifdef SQLITE_OMIT_BUILTIN_TEST
+  UNUSED_PARAMETER(op);
+#else
+  va_list ap;
+  va_start(ap, op);
+  switch( op ){
+
+    /*
+    ** Save the current state of the PRNG.
+    */
+    case SQLITE_TESTCTRL_PRNG_SAVE: {
+      sqlite3PrngSaveState();
+      break;
+    }
+
+    /*
+    ** Restore the state of the PRNG to the last state saved using
+    ** PRNG_SAVE.  If PRNG_SAVE has never before been called, then
+    ** this verb acts like PRNG_RESET.
+    */
+    case SQLITE_TESTCTRL_PRNG_RESTORE: {
+      sqlite3PrngRestoreState();
+      break;
+    }
+
+    /*
+    ** Reset the PRNG back to its uninitialized state.  The next call
+    ** to sqlite3_randomness() will reseed the PRNG using a single call
+    ** to the xRandomness method of the default VFS.
+    */
+    case SQLITE_TESTCTRL_PRNG_RESET: {
+      sqlite3_randomness(0,0);
+      break;
+    }
+
+    /*
+    **  sqlite3_test_control(BITVEC_TEST, size, program)
+    **
+    ** Run a test against a Bitvec object of size.  The program argument
+    ** is an array of integers that defines the test.  Return -1 on a
+    ** memory allocation error, 0 on success, or non-zero for an error.
+    ** See the sqlite3BitvecBuiltinTest() for additional information.
+    */
+    case SQLITE_TESTCTRL_BITVEC_TEST: {
+      int sz = va_arg(ap, int);
+      int *aProg = va_arg(ap, int*);
+      rc = sqlite3BitvecBuiltinTest(sz, aProg);
+      break;
+    }
+
+    /*
+    **  sqlite3_test_control(FAULT_INSTALL, xCallback)
+    **
+    ** Arrange to invoke xCallback() whenever sqlite3FaultSim() is called,
+    ** if xCallback is not NULL.
+    **
+    ** As a test of the fault simulator mechanism itself, sqlite3FaultSim(0)
+    ** is called immediately after installing the new callback and the return
+    ** value from sqlite3FaultSim(0) becomes the return from
+    ** sqlite3_test_control().
+    */
+    case SQLITE_TESTCTRL_FAULT_INSTALL: {
+      /* MSVC is picky about pulling func ptrs from va lists.
+      ** http://support.microsoft.com/kb/47961
+      ** sqlite3GlobalConfig.xTestCallback = va_arg(ap, int(*)(int));
+      */
+      typedef int(*TESTCALLBACKFUNC_t)(int);
+      sqlite3GlobalConfig.xTestCallback = va_arg(ap, TESTCALLBACKFUNC_t);
+      rc = sqlite3FaultSim(0);
+      break;
+    }
+
+    /*
+    **  sqlite3_test_control(BENIGN_MALLOC_HOOKS, xBegin, xEnd)
+    **
+    ** Register hooks to call to indicate which malloc() failures 
+    ** are benign.
+    */
+    case SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS: {
+      typedef void (*void_function)(void);
+      void_function xBenignBegin;
+      void_function xBenignEnd;
+      xBenignBegin = va_arg(ap, void_function);
+      xBenignEnd = va_arg(ap, void_function);
+      sqlite3BenignMallocHooks(xBenignBegin, xBenignEnd);
+      break;
+    }
+
+    /*
+    **  sqlite3_test_control(SQLITE_TESTCTRL_PENDING_BYTE, unsigned int X)
+    **
+    ** Set the PENDING byte to the value in the argument, if X>0.
+    ** Make no changes if X==0.  Return the value of the pending byte
+    ** as it existing before this routine was called.
+    **
+    ** IMPORTANT:  Changing the PENDING byte from 0x40000000 results in
+    ** an incompatible database file format.  Changing the PENDING byte
+    ** while any database connection is open results in undefined and
+    ** deleterious behavior.
+    */
+    case SQLITE_TESTCTRL_PENDING_BYTE: {
+      rc = PENDING_BYTE;
+#ifndef SQLITE_OMIT_WSD
+      {
+        unsigned int newVal = va_arg(ap, unsigned int);
+        if( newVal ) sqlite3PendingByte = newVal;
+      }
+#endif
+      break;
+    }
+
+    /*
+    **  sqlite3_test_control(SQLITE_TESTCTRL_ASSERT, int X)
+    **
+    ** This action provides a run-time test to see whether or not
+    ** assert() was enabled at compile-time.  If X is true and assert()
+    ** is enabled, then the return value is true.  If X is true and
+    ** assert() is disabled, then the return value is zero.  If X is
+    ** false and assert() is enabled, then the assertion fires and the
+    ** process aborts.  If X is false and assert() is disabled, then the
+    ** return value is zero.
+    */
+    case SQLITE_TESTCTRL_ASSERT: {
+      volatile int x = 0;
+      assert( /*side-effects-ok*/ (x = va_arg(ap,int))!=0 );
+      rc = x;
+      break;
+    }
+
+
+    /*
+    **  sqlite3_test_control(SQLITE_TESTCTRL_ALWAYS, int X)
+    **
+    ** This action provides a run-time test to see how the ALWAYS and
+    ** NEVER macros were defined at compile-time.
+    **
+    ** The return value is ALWAYS(X).  
+    **
+    ** The recommended test is X==2.  If the return value is 2, that means
+    ** ALWAYS() and NEVER() are both no-op pass-through macros, which is the
+    ** default setting.  If the return value is 1, then ALWAYS() is either
+    ** hard-coded to true or else it asserts if its argument is false.
+    ** The first behavior (hard-coded to true) is the case if
+    ** SQLITE_TESTCTRL_ASSERT shows that assert() is disabled and the second
+    ** behavior (assert if the argument to ALWAYS() is false) is the case if
+    ** SQLITE_TESTCTRL_ASSERT shows that assert() is enabled.
+    **
+    ** The run-time test procedure might look something like this:
+    **
+    **    if( sqlite3_test_control(SQLITE_TESTCTRL_ALWAYS, 2)==2 ){
+    **      // ALWAYS() and NEVER() are no-op pass-through macros
+    **    }else if( sqlite3_test_control(SQLITE_TESTCTRL_ASSERT, 1) ){
+    **      // ALWAYS(x) asserts that x is true. NEVER(x) asserts x is false.
+    **    }else{
+    **      // ALWAYS(x) is a constant 1.  NEVER(x) is a constant 0.
+    **    }
+    */
+    case SQLITE_TESTCTRL_ALWAYS: {
+      int x = va_arg(ap,int);
+      rc = ALWAYS(x);
+      break;
+    }
+
+    /*
+    **   sqlite3_test_control(SQLITE_TESTCTRL_BYTEORDER);
+    **
+    ** The integer returned reveals the byte-order of the computer on which
+    ** SQLite is running:
+    **
+    **       1     big-endian,    determined at run-time
+    **      10     little-endian, determined at run-time
+    **  432101     big-endian,    determined at compile-time
+    **  123410     little-endian, determined at compile-time
+    */ 
+    case SQLITE_TESTCTRL_BYTEORDER: {
+      rc = SQLITE_BYTEORDER*100 + SQLITE_LITTLEENDIAN*10 + SQLITE_BIGENDIAN;
+      break;
+    }
+
+    /*   sqlite3_test_control(SQLITE_TESTCTRL_RESERVE, sqlite3 *db, int N)
+    **
+    ** Set the nReserve size to N for the main database on the database
+    ** connection db.
+    */
+    case SQLITE_TESTCTRL_RESERVE: {
+      sqlite3 *db = va_arg(ap, sqlite3*);
+      int x = va_arg(ap,int);
+      sqlite3_mutex_enter(db->mutex);
+      sqlite3BtreeSetPageSize(db->aDb[0].pBt, 0, x, 0);
+      sqlite3_mutex_leave(db->mutex);
+      break;
+    }
+
+    /*  sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS, sqlite3 *db, int N)
+    **
+    ** Enable or disable various optimizations for testing purposes.  The 
+    ** argument N is a bitmask of optimizations to be disabled.  For normal
+    ** operation N should be 0.  The idea is that a test program (like the
+    ** SQL Logic Test or SLT test module) can run the same SQL multiple times
+    ** with various optimizations disabled to verify that the same answer
+    ** is obtained in every case.
+    */
+    case SQLITE_TESTCTRL_OPTIMIZATIONS: {
+      sqlite3 *db = va_arg(ap, sqlite3*);
+      db->dbOptFlags = (u16)(va_arg(ap, int) & 0xffff);
+      break;
+    }
+
+#ifdef SQLITE_N_KEYWORD
+    /* sqlite3_test_control(SQLITE_TESTCTRL_ISKEYWORD, const char *zWord)
+    **
+    ** If zWord is a keyword recognized by the parser, then return the
+    ** number of keywords.  Or if zWord is not a keyword, return 0.
+    ** 
+    ** This test feature is only available in the amalgamation since
+    ** the SQLITE_N_KEYWORD macro is not defined in this file if SQLite
+    ** is built using separate source files.
+    */
+    case SQLITE_TESTCTRL_ISKEYWORD: {
+      const char *zWord = va_arg(ap, const char*);
+      int n = sqlite3Strlen30(zWord);
+      rc = (sqlite3KeywordCode((u8*)zWord, n)!=TK_ID) ? SQLITE_N_KEYWORD : 0;
+      break;
+    }
+#endif 
+
+    /* sqlite3_test_control(SQLITE_TESTCTRL_SCRATCHMALLOC, sz, &pNew, pFree);
+    **
+    ** Pass pFree into sqlite3ScratchFree(). 
+    ** If sz>0 then allocate a scratch buffer into pNew.  
+    */
+    case SQLITE_TESTCTRL_SCRATCHMALLOC: {
+      void *pFree, **ppNew;
+      int sz;
+      sz = va_arg(ap, int);
+      ppNew = va_arg(ap, void**);
+      pFree = va_arg(ap, void*);
+      if( sz ) *ppNew = sqlite3ScratchMalloc(sz);
+      sqlite3ScratchFree(pFree);
+      break;
+    }
+
+    /*   sqlite3_test_control(SQLITE_TESTCTRL_LOCALTIME_FAULT, int onoff);
+    **
+    ** If parameter onoff is non-zero, configure the wrappers so that all
+    ** subsequent calls to localtime() and variants fail. If onoff is zero,
+    ** undo this setting.
+    */
+    case SQLITE_TESTCTRL_LOCALTIME_FAULT: {
+      sqlite3GlobalConfig.bLocaltimeFault = va_arg(ap, int);
+      break;
+    }
+
+    /*   sqlite3_test_control(SQLITE_TESTCTRL_NEVER_CORRUPT, int);
+    **
+    ** Set or clear a flag that indicates that the database file is always well-
+    ** formed and never corrupt.  This flag is clear by default, indicating that
+    ** database files might have arbitrary corruption.  Setting the flag during
+    ** testing causes certain assert() statements in the code to be activated
+    ** that demonstrat invariants on well-formed database files.
+    */
+    case SQLITE_TESTCTRL_NEVER_CORRUPT: {
+      sqlite3GlobalConfig.neverCorrupt = va_arg(ap, int);
+      break;
+    }
+
+    /* Set the threshold at which OP_Once counters reset back to zero.
+    ** By default this is 0x7ffffffe (over 2 billion), but that value is
+    ** too big to test in a reasonable amount of time, so this control is
+    ** provided to set a small and easily reachable reset value.
+    */
+    case SQLITE_TESTCTRL_ONCE_RESET_THRESHOLD: {
+      sqlite3GlobalConfig.iOnceResetThreshold = va_arg(ap, int);
+      break;
+    }
+
+    /*   sqlite3_test_control(SQLITE_TESTCTRL_VDBE_COVERAGE, xCallback, ptr);
+    **
+    ** Set the VDBE coverage callback function to xCallback with context 
+    ** pointer ptr.
+    */
+    case SQLITE_TESTCTRL_VDBE_COVERAGE: {
+#ifdef SQLITE_VDBE_COVERAGE
+      typedef void (*branch_callback)(void*,int,u8,u8);
+      sqlite3GlobalConfig.xVdbeBranch = va_arg(ap,branch_callback);
+      sqlite3GlobalConfig.pVdbeBranchArg = va_arg(ap,void*);
+#endif
+      break;
+    }
+
+    /*   sqlite3_test_control(SQLITE_TESTCTRL_SORTER_MMAP, db, nMax); */
+    case SQLITE_TESTCTRL_SORTER_MMAP: {
+      sqlite3 *db = va_arg(ap, sqlite3*);
+      db->nMaxSorterMmap = va_arg(ap, int);
+      break;
+    }
+
+    /*   sqlite3_test_control(SQLITE_TESTCTRL_ISINIT);
+    **
+    ** Return SQLITE_OK if SQLite has been initialized and SQLITE_ERROR if
+    ** not.
+    */
+    case SQLITE_TESTCTRL_ISINIT: {
+      if( sqlite3GlobalConfig.isInit==0 ) rc = SQLITE_ERROR;
+      break;
+    }
+
+    /*  sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, db, dbName, onOff, tnum);
+    **
+    ** This test control is used to create imposter tables.  "db" is a pointer
+    ** to the database connection.  dbName is the database name (ex: "main" or
+    ** "temp") which will receive the imposter.  "onOff" turns imposter mode on
+    ** or off.  "tnum" is the root page of the b-tree to which the imposter
+    ** table should connect.
+    **
+    ** Enable imposter mode only when the schema has already been parsed.  Then
+    ** run a single CREATE TABLE statement to construct the imposter table in
+    ** the parsed schema.  Then turn imposter mode back off again.
+    **
+    ** If onOff==0 and tnum>0 then reset the schema for all databases, causing
+    ** the schema to be reparsed the next time it is needed.  This has the
+    ** effect of erasing all imposter tables.
+    */
+    case SQLITE_TESTCTRL_IMPOSTER: {
+      sqlite3 *db = va_arg(ap, sqlite3*);
+      sqlite3_mutex_enter(db->mutex);
+      db->init.iDb = sqlite3FindDbName(db, va_arg(ap,const char*));
+      db->init.busy = db->init.imposterTable = va_arg(ap,int);
+      db->init.newTnum = va_arg(ap,int);
+      if( db->init.busy==0 && db->init.newTnum>0 ){
+        sqlite3ResetAllSchemasOfConnection(db);
+      }
+      sqlite3_mutex_leave(db->mutex);
+      break;
+    }
+  }
+  va_end(ap);
+#endif /* SQLITE_OMIT_BUILTIN_TEST */
+  return rc;
+}
+
+/*
+** This is a utility routine, useful to VFS implementations, that checks
+** to see if a database file was a URI that contained a specific query 
+** parameter, and if so obtains the value of the query parameter.
+**
+** The zFilename argument is the filename pointer passed into the xOpen()
+** method of a VFS implementation.  The zParam argument is the name of the
+** query parameter we seek.  This routine returns the value of the zParam
+** parameter if it exists.  If the parameter does not exist, this routine
+** returns a NULL pointer.
+*/
+SQLITE_API const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam){
+  if( zFilename==0 || zParam==0 ) return 0;
+  zFilename += sqlite3Strlen30(zFilename) + 1;
+  while( zFilename[0] ){
+    int x = strcmp(zFilename, zParam);
+    zFilename += sqlite3Strlen30(zFilename) + 1;
+    if( x==0 ) return zFilename;
+    zFilename += sqlite3Strlen30(zFilename) + 1;
+  }
+  return 0;
+}
+
+/*
+** Return a boolean value for a query parameter.
+*/
+SQLITE_API int sqlite3_uri_boolean(const char *zFilename, const char *zParam, int bDflt){
+  const char *z = sqlite3_uri_parameter(zFilename, zParam);
+  bDflt = bDflt!=0;
+  return z ? sqlite3GetBoolean(z, bDflt) : bDflt;
+}
+
+/*
+** Return a 64-bit integer value for a query parameter.
+*/
+SQLITE_API sqlite3_int64 sqlite3_uri_int64(
+  const char *zFilename,    /* Filename as passed to xOpen */
+  const char *zParam,       /* URI parameter sought */
+  sqlite3_int64 bDflt       /* return if parameter is missing */
+){
+  const char *z = sqlite3_uri_parameter(zFilename, zParam);
+  sqlite3_int64 v;
+  if( z && sqlite3DecOrHexToI64(z, &v)==SQLITE_OK ){
+    bDflt = v;
+  }
+  return bDflt;
+}
+
+/*
+** Return the Btree pointer identified by zDbName.  Return NULL if not found.
+*/
+SQLITE_PRIVATE Btree *sqlite3DbNameToBtree(sqlite3 *db, const char *zDbName){
+  int i;
+  for(i=0; i<db->nDb; i++){
+    if( db->aDb[i].pBt
+     && (zDbName==0 || sqlite3StrICmp(zDbName, db->aDb[i].zDbSName)==0)
+    ){
+      return db->aDb[i].pBt;
+    }
+  }
+  return 0;
+}
+
+/*
+** Return the filename of the database associated with a database
+** connection.
+*/
+SQLITE_API const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName){
+  Btree *pBt;
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return 0;
+  }
+#endif
+  pBt = sqlite3DbNameToBtree(db, zDbName);
+  return pBt ? sqlite3BtreeGetFilename(pBt) : 0;
+}
+
+/*
+** Return 1 if database is read-only or 0 if read/write.  Return -1 if
+** no such database exists.
+*/
+SQLITE_API int sqlite3_db_readonly(sqlite3 *db, const char *zDbName){
+  Btree *pBt;
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return -1;
+  }
+#endif
+  pBt = sqlite3DbNameToBtree(db, zDbName);
+  return pBt ? sqlite3BtreeIsReadonly(pBt) : -1;
+}
+
+#ifdef SQLITE_ENABLE_SNAPSHOT
+/*
+** Obtain a snapshot handle for the snapshot of database zDb currently 
+** being read by handle db.
+*/
+SQLITE_API int sqlite3_snapshot_get(
+  sqlite3 *db, 
+  const char *zDb,
+  sqlite3_snapshot **ppSnapshot
+){
+  int rc = SQLITE_ERROR;
+#ifndef SQLITE_OMIT_WAL
+  int iDb;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    return SQLITE_MISUSE_BKPT;
+  }
+#endif
+  sqlite3_mutex_enter(db->mutex);
+
+  iDb = sqlite3FindDbName(db, zDb);
+  if( iDb==0 || iDb>1 ){
+    Btree *pBt = db->aDb[iDb].pBt;
+    if( 0==sqlite3BtreeIsInTrans(pBt) ){
+      rc = sqlite3BtreeBeginTrans(pBt, 0);
+      if( rc==SQLITE_OK ){
+        rc = sqlite3PagerSnapshotGet(sqlite3BtreePager(pBt), ppSnapshot);
+      }
+    }
+  }
+
+  sqlite3_mutex_leave(db->mutex);
+#endif   /* SQLITE_OMIT_WAL */
+  return rc;
+}
+
+/*
+** Open a read-transaction on the snapshot idendified by pSnapshot.
+*/
+SQLITE_API int sqlite3_snapshot_open(
+  sqlite3 *db, 
+  const char *zDb, 
+  sqlite3_snapshot *pSnapshot
+){
+  int rc = SQLITE_ERROR;
+#ifndef SQLITE_OMIT_WAL
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    return SQLITE_MISUSE_BKPT;
+  }
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  if( db->autoCommit==0 ){
+    int iDb;
+    iDb = sqlite3FindDbName(db, zDb);
+    if( iDb==0 || iDb>1 ){
+      Btree *pBt = db->aDb[iDb].pBt;
+      if( 0==sqlite3BtreeIsInReadTrans(pBt) ){
+        rc = sqlite3PagerSnapshotOpen(sqlite3BtreePager(pBt), pSnapshot);
+        if( rc==SQLITE_OK ){
+          rc = sqlite3BtreeBeginTrans(pBt, 0);
+          sqlite3PagerSnapshotOpen(sqlite3BtreePager(pBt), 0);
+        }
+      }
+    }
+  }
+
+  sqlite3_mutex_leave(db->mutex);
+#endif   /* SQLITE_OMIT_WAL */
+  return rc;
+}
+
+/*
+** Free a snapshot handle obtained from sqlite3_snapshot_get().
+*/
+SQLITE_API void sqlite3_snapshot_free(sqlite3_snapshot *pSnapshot){
+  sqlite3_free(pSnapshot);
+}
+#endif /* SQLITE_ENABLE_SNAPSHOT */
+
+/************** End of main.c ************************************************/
+/************** Begin file notify.c ******************************************/
+/*
+** 2009 March 3
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains the implementation of the sqlite3_unlock_notify()
+** API method and its associated functionality.
+*/
+/* #include "sqliteInt.h" */
+/* #include "btreeInt.h" */
+
+/* Omit this entire file if SQLITE_ENABLE_UNLOCK_NOTIFY is not defined. */
+#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
+
+/*
+** Public interfaces:
+**
+**   sqlite3ConnectionBlocked()
+**   sqlite3ConnectionUnlocked()
+**   sqlite3ConnectionClosed()
+**   sqlite3_unlock_notify()
+*/
+
+#define assertMutexHeld() \
+  assert( sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER)) )
+
+/*
+** Head of a linked list of all sqlite3 objects created by this process
+** for which either sqlite3.pBlockingConnection or sqlite3.pUnlockConnection
+** is not NULL. This variable may only accessed while the STATIC_MASTER
+** mutex is held.
+*/
+static sqlite3 *SQLITE_WSD sqlite3BlockedList = 0;
+
+#ifndef NDEBUG
+/*
+** This function is a complex assert() that verifies the following 
+** properties of the blocked connections list:
+**
+**   1) Each entry in the list has a non-NULL value for either 
+**      pUnlockConnection or pBlockingConnection, or both.
+**
+**   2) All entries in the list that share a common value for 
+**      xUnlockNotify are grouped together.
+**
+**   3) If the argument db is not NULL, then none of the entries in the
+**      blocked connections list have pUnlockConnection or pBlockingConnection
+**      set to db. This is used when closing connection db.
+*/
+static void checkListProperties(sqlite3 *db){
+  sqlite3 *p;
+  for(p=sqlite3BlockedList; p; p=p->pNextBlocked){
+    int seen = 0;
+    sqlite3 *p2;
+
+    /* Verify property (1) */
+    assert( p->pUnlockConnection || p->pBlockingConnection );
+
+    /* Verify property (2) */
+    for(p2=sqlite3BlockedList; p2!=p; p2=p2->pNextBlocked){
+      if( p2->xUnlockNotify==p->xUnlockNotify ) seen = 1;
+      assert( p2->xUnlockNotify==p->xUnlockNotify || !seen );
+      assert( db==0 || p->pUnlockConnection!=db );
+      assert( db==0 || p->pBlockingConnection!=db );
+    }
+  }
+}
+#else
+# define checkListProperties(x)
+#endif
+
+/*
+** Remove connection db from the blocked connections list. If connection
+** db is not currently a part of the list, this function is a no-op.
+*/
+static void removeFromBlockedList(sqlite3 *db){
+  sqlite3 **pp;
+  assertMutexHeld();
+  for(pp=&sqlite3BlockedList; *pp; pp = &(*pp)->pNextBlocked){
+    if( *pp==db ){
+      *pp = (*pp)->pNextBlocked;
+      break;
+    }
+  }
+}
+
+/*
+** Add connection db to the blocked connections list. It is assumed
+** that it is not already a part of the list.
+*/
+static void addToBlockedList(sqlite3 *db){
+  sqlite3 **pp;
+  assertMutexHeld();
+  for(
+    pp=&sqlite3BlockedList; 
+    *pp && (*pp)->xUnlockNotify!=db->xUnlockNotify; 
+    pp=&(*pp)->pNextBlocked
+  );
+  db->pNextBlocked = *pp;
+  *pp = db;
+}
+
+/*
+** Obtain the STATIC_MASTER mutex.
+*/
+static void enterMutex(void){
+  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+  checkListProperties(0);
+}
+
+/*
+** Release the STATIC_MASTER mutex.
+*/
+static void leaveMutex(void){
+  assertMutexHeld();
+  checkListProperties(0);
+  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+}
+
+/*
+** Register an unlock-notify callback.
+**
+** This is called after connection "db" has attempted some operation
+** but has received an SQLITE_LOCKED error because another connection
+** (call it pOther) in the same process was busy using the same shared
+** cache.  pOther is found by looking at db->pBlockingConnection.
+**
+** If there is no blocking connection, the callback is invoked immediately,
+** before this routine returns.
+**
+** If pOther is already blocked on db, then report SQLITE_LOCKED, to indicate
+** a deadlock.
+**
+** Otherwise, make arrangements to invoke xNotify when pOther drops
+** its locks.
+**
+** Each call to this routine overrides any prior callbacks registered
+** on the same "db".  If xNotify==0 then any prior callbacks are immediately
+** cancelled.
+*/
+SQLITE_API int sqlite3_unlock_notify(
+  sqlite3 *db,
+  void (*xNotify)(void **, int),
+  void *pArg
+){
+  int rc = SQLITE_OK;
+
+  sqlite3_mutex_enter(db->mutex);
+  enterMutex();
+
+  if( xNotify==0 ){
+    removeFromBlockedList(db);
+    db->pBlockingConnection = 0;
+    db->pUnlockConnection = 0;
+    db->xUnlockNotify = 0;
+    db->pUnlockArg = 0;
+  }else if( 0==db->pBlockingConnection ){
+    /* The blocking transaction has been concluded. Or there never was a 
+    ** blocking transaction. In either case, invoke the notify callback
+    ** immediately. 
+    */
+    xNotify(&pArg, 1);
+  }else{
+    sqlite3 *p;
+
+    for(p=db->pBlockingConnection; p && p!=db; p=p->pUnlockConnection){}
+    if( p ){
+      rc = SQLITE_LOCKED;              /* Deadlock detected. */
+    }else{
+      db->pUnlockConnection = db->pBlockingConnection;
+      db->xUnlockNotify = xNotify;
+      db->pUnlockArg = pArg;
+      removeFromBlockedList(db);
+      addToBlockedList(db);
+    }
+  }
+
+  leaveMutex();
+  assert( !db->mallocFailed );
+  sqlite3ErrorWithMsg(db, rc, (rc?"database is deadlocked":0));
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+/*
+** This function is called while stepping or preparing a statement 
+** associated with connection db. The operation will return SQLITE_LOCKED
+** to the user because it requires a lock that will not be available
+** until connection pBlocker concludes its current transaction.
+*/
+SQLITE_PRIVATE void sqlite3ConnectionBlocked(sqlite3 *db, sqlite3 *pBlocker){
+  enterMutex();
+  if( db->pBlockingConnection==0 && db->pUnlockConnection==0 ){
+    addToBlockedList(db);
+  }
+  db->pBlockingConnection = pBlocker;
+  leaveMutex();
+}
+
+/*
+** This function is called when
+** the transaction opened by database db has just finished. Locks held 
+** by database connection db have been released.
+**
+** This function loops through each entry in the blocked connections
+** list and does the following:
+**
+**   1) If the sqlite3.pBlockingConnection member of a list entry is
+**      set to db, then set pBlockingConnection=0.
+**
+**   2) If the sqlite3.pUnlockConnection member of a list entry is
+**      set to db, then invoke the configured unlock-notify callback and
+**      set pUnlockConnection=0.
+**
+**   3) If the two steps above mean that pBlockingConnection==0 and
+**      pUnlockConnection==0, remove the entry from the blocked connections
+**      list.
+*/
+SQLITE_PRIVATE void sqlite3ConnectionUnlocked(sqlite3 *db){
+  void (*xUnlockNotify)(void **, int) = 0; /* Unlock-notify cb to invoke */
+  int nArg = 0;                            /* Number of entries in aArg[] */
+  sqlite3 **pp;                            /* Iterator variable */
+  void **aArg;               /* Arguments to the unlock callback */
+  void **aDyn = 0;           /* Dynamically allocated space for aArg[] */
+  void *aStatic[16];         /* Starter space for aArg[].  No malloc required */
+
+  aArg = aStatic;
+  enterMutex();         /* Enter STATIC_MASTER mutex */
+
+  /* This loop runs once for each entry in the blocked-connections list. */
+  for(pp=&sqlite3BlockedList; *pp; /* no-op */ ){
+    sqlite3 *p = *pp;
+
+    /* Step 1. */
+    if( p->pBlockingConnection==db ){
+      p->pBlockingConnection = 0;
+    }
+
+    /* Step 2. */
+    if( p->pUnlockConnection==db ){
+      assert( p->xUnlockNotify );
+      if( p->xUnlockNotify!=xUnlockNotify && nArg!=0 ){
+        xUnlockNotify(aArg, nArg);
+        nArg = 0;
+      }
+
+      sqlite3BeginBenignMalloc();
+      assert( aArg==aDyn || (aDyn==0 && aArg==aStatic) );
+      assert( nArg<=(int)ArraySize(aStatic) || aArg==aDyn );
+      if( (!aDyn && nArg==(int)ArraySize(aStatic))
+       || (aDyn && nArg==(int)(sqlite3MallocSize(aDyn)/sizeof(void*)))
+      ){
+        /* The aArg[] array needs to grow. */
+        void **pNew = (void **)sqlite3Malloc(nArg*sizeof(void *)*2);
+        if( pNew ){
+          memcpy(pNew, aArg, nArg*sizeof(void *));
+          sqlite3_free(aDyn);
+          aDyn = aArg = pNew;
+        }else{
+          /* This occurs when the array of context pointers that need to
+          ** be passed to the unlock-notify callback is larger than the
+          ** aStatic[] array allocated on the stack and the attempt to 
+          ** allocate a larger array from the heap has failed.
+          **
+          ** This is a difficult situation to handle. Returning an error
+          ** code to the caller is insufficient, as even if an error code
+          ** is returned the transaction on connection db will still be
+          ** closed and the unlock-notify callbacks on blocked connections
+          ** will go unissued. This might cause the application to wait
+          ** indefinitely for an unlock-notify callback that will never 
+          ** arrive.
+          **
+          ** Instead, invoke the unlock-notify callback with the context
+          ** array already accumulated. We can then clear the array and
+          ** begin accumulating any further context pointers without 
+          ** requiring any dynamic allocation. This is sub-optimal because
+          ** it means that instead of one callback with a large array of
+          ** context pointers the application will receive two or more
+          ** callbacks with smaller arrays of context pointers, which will
+          ** reduce the applications ability to prioritize multiple 
+          ** connections. But it is the best that can be done under the
+          ** circumstances.
+          */
+          xUnlockNotify(aArg, nArg);
+          nArg = 0;
+        }
+      }
+      sqlite3EndBenignMalloc();
+
+      aArg[nArg++] = p->pUnlockArg;
+      xUnlockNotify = p->xUnlockNotify;
+      p->pUnlockConnection = 0;
+      p->xUnlockNotify = 0;
+      p->pUnlockArg = 0;
+    }
+
+    /* Step 3. */
+    if( p->pBlockingConnection==0 && p->pUnlockConnection==0 ){
+      /* Remove connection p from the blocked connections list. */
+      *pp = p->pNextBlocked;
+      p->pNextBlocked = 0;
+    }else{
+      pp = &p->pNextBlocked;
+    }
+  }
+
+  if( nArg!=0 ){
+    xUnlockNotify(aArg, nArg);
+  }
+  sqlite3_free(aDyn);
+  leaveMutex();         /* Leave STATIC_MASTER mutex */
+}
+
+/*
+** This is called when the database connection passed as an argument is 
+** being closed. The connection is removed from the blocked list.
+*/
+SQLITE_PRIVATE void sqlite3ConnectionClosed(sqlite3 *db){
+  sqlite3ConnectionUnlocked(db);
+  enterMutex();
+  removeFromBlockedList(db);
+  checkListProperties(db);
+  leaveMutex();
+}
+#endif
+
+/************** End of notify.c **********************************************/
+/************** Begin file fts3.c ********************************************/
+/*
+** 2006 Oct 10
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This is an SQLite module implementing full-text search.
+*/
+
+/*
+** The code in this file is only compiled if:
+**
+**     * The FTS3 module is being built as an extension
+**       (in which case SQLITE_CORE is not defined), or
+**
+**     * The FTS3 module is being built into the core of
+**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
+*/
+
+/* The full-text index is stored in a series of b+tree (-like)
+** structures called segments which map terms to doclists.  The
+** structures are like b+trees in layout, but are constructed from the
+** bottom up in optimal fashion and are not updatable.  Since trees
+** are built from the bottom up, things will be described from the
+** bottom up.
+**
+**
+**** Varints ****
+** The basic unit of encoding is a variable-length integer called a
+** varint.  We encode variable-length integers in little-endian order
+** using seven bits * per byte as follows:
+**
+** KEY:
+**         A = 0xxxxxxx    7 bits of data and one flag bit
+**         B = 1xxxxxxx    7 bits of data and one flag bit
+**
+**  7 bits - A
+** 14 bits - BA
+** 21 bits - BBA
+** and so on.
+**
+** This is similar in concept to how sqlite encodes "varints" but
+** the encoding is not the same.  SQLite varints are big-endian
+** are are limited to 9 bytes in length whereas FTS3 varints are
+** little-endian and can be up to 10 bytes in length (in theory).
+**
+** Example encodings:
+**
+**     1:    0x01
+**   127:    0x7f
+**   128:    0x81 0x00
+**
+**
+**** Document lists ****
+** A doclist (document list) holds a docid-sorted list of hits for a
+** given term.  Doclists hold docids and associated token positions.
+** A docid is the unique integer identifier for a single document.
+** A position is the index of a word within the document.  The first 
+** word of the document has a position of 0.
+**
+** FTS3 used to optionally store character offsets using a compile-time
+** option.  But that functionality is no longer supported.
+**
+** A doclist is stored like this:
+**
+** array {
+**   varint docid;          (delta from previous doclist)
+**   array {                (position list for column 0)
+**     varint position;     (2 more than the delta from previous position)
+**   }
+**   array {
+**     varint POS_COLUMN;   (marks start of position list for new column)
+**     varint column;       (index of new column)
+**     array {
+**       varint position;   (2 more than the delta from previous position)
+**     }
+**   }
+**   varint POS_END;        (marks end of positions for this document.
+** }
+**
+** Here, array { X } means zero or more occurrences of X, adjacent in
+** memory.  A "position" is an index of a token in the token stream
+** generated by the tokenizer. Note that POS_END and POS_COLUMN occur 
+** in the same logical place as the position element, and act as sentinals
+** ending a position list array.  POS_END is 0.  POS_COLUMN is 1.
+** The positions numbers are not stored literally but rather as two more
+** than the difference from the prior position, or the just the position plus
+** 2 for the first position.  Example:
+**
+**   label:       A B C D E  F  G H   I  J K
+**   value:     123 5 9 1 1 14 35 0 234 72 0
+**
+** The 123 value is the first docid.  For column zero in this document
+** there are two matches at positions 3 and 10 (5-2 and 9-2+3).  The 1
+** at D signals the start of a new column; the 1 at E indicates that the
+** new column is column number 1.  There are two positions at 12 and 45
+** (14-2 and 35-2+12).  The 0 at H indicate the end-of-document.  The
+** 234 at I is the delta to next docid (357).  It has one position 70
+** (72-2) and then terminates with the 0 at K.
+**
+** A "position-list" is the list of positions for multiple columns for
+** a single docid.  A "column-list" is the set of positions for a single
+** column.  Hence, a position-list consists of one or more column-lists,
+** a document record consists of a docid followed by a position-list and
+** a doclist consists of one or more document records.
+**
+** A bare doclist omits the position information, becoming an 
+** array of varint-encoded docids.
+**
+**** Segment leaf nodes ****
+** Segment leaf nodes store terms and doclists, ordered by term.  Leaf
+** nodes are written using LeafWriter, and read using LeafReader (to
+** iterate through a single leaf node's data) and LeavesReader (to
+** iterate through a segment's entire leaf layer).  Leaf nodes have
+** the format:
+**
+** varint iHeight;             (height from leaf level, always 0)
+** varint nTerm;               (length of first term)
+** char pTerm[nTerm];          (content of first term)
+** varint nDoclist;            (length of term's associated doclist)
+** char pDoclist[nDoclist];    (content of doclist)
+** array {
+**                             (further terms are delta-encoded)
+**   varint nPrefix;           (length of prefix shared with previous term)
+**   varint nSuffix;           (length of unshared suffix)
+**   char pTermSuffix[nSuffix];(unshared suffix of next term)
+**   varint nDoclist;          (length of term's associated doclist)
+**   char pDoclist[nDoclist];  (content of doclist)
+** }
+**
+** Here, array { X } means zero or more occurrences of X, adjacent in
+** memory.
+**
+** Leaf nodes are broken into blocks which are stored contiguously in
+** the %_segments table in sorted order.  This means that when the end
+** of a node is reached, the next term is in the node with the next
+** greater node id.
+**
+** New data is spilled to a new leaf node when the current node
+** exceeds LEAF_MAX bytes (default 2048).  New data which itself is
+** larger than STANDALONE_MIN (default 1024) is placed in a standalone
+** node (a leaf node with a single term and doclist).  The goal of
+** these settings is to pack together groups of small doclists while
+** making it efficient to directly access large doclists.  The
+** assumption is that large doclists represent terms which are more
+** likely to be query targets.
+**
+** TODO(shess) It may be useful for blocking decisions to be more
+** dynamic.  For instance, it may make more sense to have a 2.5k leaf
+** node rather than splitting into 2k and .5k nodes.  My intuition is
+** that this might extend through 2x or 4x the pagesize.
+**
+**
+**** Segment interior nodes ****
+** Segment interior nodes store blockids for subtree nodes and terms
+** to describe what data is stored by the each subtree.  Interior
+** nodes are written using InteriorWriter, and read using
+** InteriorReader.  InteriorWriters are created as needed when
+** SegmentWriter creates new leaf nodes, or when an interior node
+** itself grows too big and must be split.  The format of interior
+** nodes:
+**
+** varint iHeight;           (height from leaf level, always >0)
+** varint iBlockid;          (block id of node's leftmost subtree)
+** optional {
+**   varint nTerm;           (length of first term)
+**   char pTerm[nTerm];      (content of first term)
+**   array {
+**                                (further terms are delta-encoded)
+**     varint nPrefix;            (length of shared prefix with previous term)
+**     varint nSuffix;            (length of unshared suffix)
+**     char pTermSuffix[nSuffix]; (unshared suffix of next term)
+**   }
+** }
+**
+** Here, optional { X } means an optional element, while array { X }
+** means zero or more occurrences of X, adjacent in memory.
+**
+** An interior node encodes n terms separating n+1 subtrees.  The
+** subtree blocks are contiguous, so only the first subtree's blockid
+** is encoded.  The subtree at iBlockid will contain all terms less
+** than the first term encoded (or all terms if no term is encoded).
+** Otherwise, for terms greater than or equal to pTerm[i] but less
+** than pTerm[i+1], the subtree for that term will be rooted at
+** iBlockid+i.  Interior nodes only store enough term data to
+** distinguish adjacent children (if the rightmost term of the left
+** child is "something", and the leftmost term of the right child is
+** "wicked", only "w" is stored).
+**
+** New data is spilled to a new interior node at the same height when
+** the current node exceeds INTERIOR_MAX bytes (default 2048).
+** INTERIOR_MIN_TERMS (default 7) keeps large terms from monopolizing
+** interior nodes and making the tree too skinny.  The interior nodes
+** at a given height are naturally tracked by interior nodes at
+** height+1, and so on.
+**
+**
+**** Segment directory ****
+** The segment directory in table %_segdir stores meta-information for
+** merging and deleting segments, and also the root node of the
+** segment's tree.
+**
+** The root node is the top node of the segment's tree after encoding
+** the entire segment, restricted to ROOT_MAX bytes (default 1024).
+** This could be either a leaf node or an interior node.  If the top
+** node requires more than ROOT_MAX bytes, it is flushed to %_segments
+** and a new root interior node is generated (which should always fit
+** within ROOT_MAX because it only needs space for 2 varints, the
+** height and the blockid of the previous root).
+**
+** The meta-information in the segment directory is:
+**   level               - segment level (see below)
+**   idx                 - index within level
+**                       - (level,idx uniquely identify a segment)
+**   start_block         - first leaf node
+**   leaves_end_block    - last leaf node
+**   end_block           - last block (including interior nodes)
+**   root                - contents of root node
+**
+** If the root node is a leaf node, then start_block,
+** leaves_end_block, and end_block are all 0.
+**
+**
+**** Segment merging ****
+** To amortize update costs, segments are grouped into levels and
+** merged in batches.  Each increase in level represents exponentially
+** more documents.
+**
+** New documents (actually, document updates) are tokenized and
+** written individually (using LeafWriter) to a level 0 segment, with
+** incrementing idx.  When idx reaches MERGE_COUNT (default 16), all
+** level 0 segments are merged into a single level 1 segment.  Level 1
+** is populated like level 0, and eventually MERGE_COUNT level 1
+** segments are merged to a single level 2 segment (representing
+** MERGE_COUNT^2 updates), and so on.
+**
+** A segment merge traverses all segments at a given level in
+** parallel, performing a straightforward sorted merge.  Since segment
+** leaf nodes are written in to the %_segments table in order, this
+** merge traverses the underlying sqlite disk structures efficiently.
+** After the merge, all segment blocks from the merged level are
+** deleted.
+**
+** MERGE_COUNT controls how often we merge segments.  16 seems to be
+** somewhat of a sweet spot for insertion performance.  32 and 64 show
+** very similar performance numbers to 16 on insertion, though they're
+** a tiny bit slower (perhaps due to more overhead in merge-time
+** sorting).  8 is about 20% slower than 16, 4 about 50% slower than
+** 16, 2 about 66% slower than 16.
+**
+** At query time, high MERGE_COUNT increases the number of segments
+** which need to be scanned and merged.  For instance, with 100k docs
+** inserted:
+**
+**    MERGE_COUNT   segments
+**       16           25
+**        8           12
+**        4           10
+**        2            6
+**
+** This appears to have only a moderate impact on queries for very
+** frequent terms (which are somewhat dominated by segment merge
+** costs), and infrequent and non-existent terms still seem to be fast
+** even with many segments.
+**
+** TODO(shess) That said, it would be nice to have a better query-side
+** argument for MERGE_COUNT of 16.  Also, it is possible/likely that
+** optimizations to things like doclist merging will swing the sweet
+** spot around.
+**
+**
+**
+**** Handling of deletions and updates ****
+** Since we're using a segmented structure, with no docid-oriented
+** index into the term index, we clearly cannot simply update the term
+** index when a document is deleted or updated.  For deletions, we
+** write an empty doclist (varint(docid) varint(POS_END)), for updates
+** we simply write the new doclist.  Segment merges overwrite older
+** data for a particular docid with newer data, so deletes or updates
+** will eventually overtake the earlier data and knock it out.  The
+** query logic likewise merges doclists so that newer data knocks out
+** older data.
+*/
+
+/************** Include fts3Int.h in the middle of fts3.c ********************/
+/************** Begin file fts3Int.h *****************************************/
+/*
+** 2009 Nov 12
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+*/
+#ifndef _FTSINT_H
+#define _FTSINT_H
+
+#if !defined(NDEBUG) && !defined(SQLITE_DEBUG) 
+# define NDEBUG 1
+#endif
+
+/* FTS3/FTS4 require virtual tables */
+#ifdef SQLITE_OMIT_VIRTUALTABLE
+# undef SQLITE_ENABLE_FTS3
+# undef SQLITE_ENABLE_FTS4
+#endif
+
+/*
+** FTS4 is really an extension for FTS3.  It is enabled using the
+** SQLITE_ENABLE_FTS3 macro.  But to avoid confusion we also all
+** the SQLITE_ENABLE_FTS4 macro to serve as an alisse for SQLITE_ENABLE_FTS3.
+*/
+#if defined(SQLITE_ENABLE_FTS4) && !defined(SQLITE_ENABLE_FTS3)
+# define SQLITE_ENABLE_FTS3
+#endif
+
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
+
+/* If not building as part of the core, include sqlite3ext.h. */
+#ifndef SQLITE_CORE
+/* # include "sqlite3ext.h"  */
+SQLITE_EXTENSION_INIT3
+#endif
+
+/* #include "sqlite3.h" */
+/************** Include fts3_tokenizer.h in the middle of fts3Int.h **********/
+/************** Begin file fts3_tokenizer.h **********************************/
+/*
+** 2006 July 10
+**
+** The author disclaims copyright to this source code.
+**
+*************************************************************************
+** Defines the interface to tokenizers used by fulltext-search.  There
+** are three basic components:
+**
+** sqlite3_tokenizer_module is a singleton defining the tokenizer
+** interface functions.  This is essentially the class structure for
+** tokenizers.
+**
+** sqlite3_tokenizer is used to define a particular tokenizer, perhaps
+** including customization information defined at creation time.
+**
+** sqlite3_tokenizer_cursor is generated by a tokenizer to generate
+** tokens from a particular input.
+*/
+#ifndef _FTS3_TOKENIZER_H_
+#define _FTS3_TOKENIZER_H_
+
+/* TODO(shess) Only used for SQLITE_OK and SQLITE_DONE at this time.
+** If tokenizers are to be allowed to call sqlite3_*() functions, then
+** we will need a way to register the API consistently.
+*/
+/* #include "sqlite3.h" */
+
+/*
+** Structures used by the tokenizer interface. When a new tokenizer
+** implementation is registered, the caller provides a pointer to
+** an sqlite3_tokenizer_module containing pointers to the callback
+** functions that make up an implementation.
+**
+** When an fts3 table is created, it passes any arguments passed to
+** the tokenizer clause of the CREATE VIRTUAL TABLE statement to the
+** sqlite3_tokenizer_module.xCreate() function of the requested tokenizer
+** implementation. The xCreate() function in turn returns an 
+** sqlite3_tokenizer structure representing the specific tokenizer to
+** be used for the fts3 table (customized by the tokenizer clause arguments).
+**
+** To tokenize an input buffer, the sqlite3_tokenizer_module.xOpen()
+** method is called. It returns an sqlite3_tokenizer_cursor object
+** that may be used to tokenize a specific input buffer based on
+** the tokenization rules supplied by a specific sqlite3_tokenizer
+** object.
+*/
+typedef struct sqlite3_tokenizer_module sqlite3_tokenizer_module;
+typedef struct sqlite3_tokenizer sqlite3_tokenizer;
+typedef struct sqlite3_tokenizer_cursor sqlite3_tokenizer_cursor;
+
+struct sqlite3_tokenizer_module {
+
+  /*
+  ** Structure version. Should always be set to 0 or 1.
+  */
+  int iVersion;
+
+  /*
+  ** Create a new tokenizer. The values in the argv[] array are the
+  ** arguments passed to the "tokenizer" clause of the CREATE VIRTUAL
+  ** TABLE statement that created the fts3 table. For example, if
+  ** the following SQL is executed:
+  **
+  **   CREATE .. USING fts3( ... , tokenizer <tokenizer-name> arg1 arg2)
+  **
+  ** then argc is set to 2, and the argv[] array contains pointers
+  ** to the strings "arg1" and "arg2".
+  **
+  ** This method should return either SQLITE_OK (0), or an SQLite error 
+  ** code. If SQLITE_OK is returned, then *ppTokenizer should be set
+  ** to point at the newly created tokenizer structure. The generic
+  ** sqlite3_tokenizer.pModule variable should not be initialized by
+  ** this callback. The caller will do so.
+  */
+  int (*xCreate)(
+    int argc,                           /* Size of argv array */
+    const char *const*argv,             /* Tokenizer argument strings */
+    sqlite3_tokenizer **ppTokenizer     /* OUT: Created tokenizer */
+  );
+
+  /*
+  ** Destroy an existing tokenizer. The fts3 module calls this method
+  ** exactly once for each successful call to xCreate().
+  */
+  int (*xDestroy)(sqlite3_tokenizer *pTokenizer);
+
+  /*
+  ** Create a tokenizer cursor to tokenize an input buffer. The caller
+  ** is responsible for ensuring that the input buffer remains valid
+  ** until the cursor is closed (using the xClose() method). 
+  */
+  int (*xOpen)(
+    sqlite3_tokenizer *pTokenizer,       /* Tokenizer object */
+    const char *pInput, int nBytes,      /* Input buffer */
+    sqlite3_tokenizer_cursor **ppCursor  /* OUT: Created tokenizer cursor */
+  );
+
+  /*
+  ** Destroy an existing tokenizer cursor. The fts3 module calls this 
+  ** method exactly once for each successful call to xOpen().
+  */
+  int (*xClose)(sqlite3_tokenizer_cursor *pCursor);
+
+  /*
+  ** Retrieve the next token from the tokenizer cursor pCursor. This
+  ** method should either return SQLITE_OK and set the values of the
+  ** "OUT" variables identified below, or SQLITE_DONE to indicate that
+  ** the end of the buffer has been reached, or an SQLite error code.
+  **
+  ** *ppToken should be set to point at a buffer containing the 
+  ** normalized version of the token (i.e. after any case-folding and/or
+  ** stemming has been performed). *pnBytes should be set to the length
+  ** of this buffer in bytes. The input text that generated the token is
+  ** identified by the byte offsets returned in *piStartOffset and
+  ** *piEndOffset. *piStartOffset should be set to the index of the first
+  ** byte of the token in the input buffer. *piEndOffset should be set
+  ** to the index of the first byte just past the end of the token in
+  ** the input buffer.
+  **
+  ** The buffer *ppToken is set to point at is managed by the tokenizer
+  ** implementation. It is only required to be valid until the next call
+  ** to xNext() or xClose(). 
+  */
+  /* TODO(shess) current implementation requires pInput to be
+  ** nul-terminated.  This should either be fixed, or pInput/nBytes
+  ** should be converted to zInput.
+  */
+  int (*xNext)(
+    sqlite3_tokenizer_cursor *pCursor,   /* Tokenizer cursor */
+    const char **ppToken, int *pnBytes,  /* OUT: Normalized text for token */
+    int *piStartOffset,  /* OUT: Byte offset of token in input buffer */
+    int *piEndOffset,    /* OUT: Byte offset of end of token in input buffer */
+    int *piPosition      /* OUT: Number of tokens returned before this one */
+  );
+
+  /***********************************************************************
+  ** Methods below this point are only available if iVersion>=1.
+  */
+
+  /* 
+  ** Configure the language id of a tokenizer cursor.
+  */
+  int (*xLanguageid)(sqlite3_tokenizer_cursor *pCsr, int iLangid);
+};
+
+struct sqlite3_tokenizer {
+  const sqlite3_tokenizer_module *pModule;  /* The module for this tokenizer */
+  /* Tokenizer implementations will typically add additional fields */
+};
+
+struct sqlite3_tokenizer_cursor {
+  sqlite3_tokenizer *pTokenizer;       /* Tokenizer for this cursor. */
+  /* Tokenizer implementations will typically add additional fields */
+};
+
+int fts3_global_term_cnt(int iTerm, int iCol);
+int fts3_term_cnt(int iTerm, int iCol);
+
+
+#endif /* _FTS3_TOKENIZER_H_ */
+
+/************** End of fts3_tokenizer.h **************************************/
+/************** Continuing where we left off in fts3Int.h ********************/
+/************** Include fts3_hash.h in the middle of fts3Int.h ***************/
+/************** Begin file fts3_hash.h ***************************************/
+/*
+** 2001 September 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This is the header file for the generic hash-table implementation
+** used in SQLite.  We've modified it slightly to serve as a standalone
+** hash table implementation for the full-text indexing module.
+**
+*/
+#ifndef _FTS3_HASH_H_
+#define _FTS3_HASH_H_
+
+/* Forward declarations of structures. */
+typedef struct Fts3Hash Fts3Hash;
+typedef struct Fts3HashElem Fts3HashElem;
+
+/* A complete hash table is an instance of the following structure.
+** The internals of this structure are intended to be opaque -- client
+** code should not attempt to access or modify the fields of this structure
+** directly.  Change this structure only by using the routines below.
+** However, many of the "procedures" and "functions" for modifying and
+** accessing this structure are really macros, so we can't really make
+** this structure opaque.
+*/
+struct Fts3Hash {
+  char keyClass;          /* HASH_INT, _POINTER, _STRING, _BINARY */
+  char copyKey;           /* True if copy of key made on insert */
+  int count;              /* Number of entries in this table */
+  Fts3HashElem *first;    /* The first element of the array */
+  int htsize;             /* Number of buckets in the hash table */
+  struct _fts3ht {        /* the hash table */
+    int count;               /* Number of entries with this hash */
+    Fts3HashElem *chain;     /* Pointer to first entry with this hash */
+  } *ht;
+};
+
+/* Each element in the hash table is an instance of the following 
+** structure.  All elements are stored on a single doubly-linked list.
+**
+** Again, this structure is intended to be opaque, but it can't really
+** be opaque because it is used by macros.
+*/
+struct Fts3HashElem {
+  Fts3HashElem *next, *prev; /* Next and previous elements in the table */
+  void *data;                /* Data associated with this element */
+  void *pKey; int nKey;      /* Key associated with this element */
+};
+
+/*
+** There are 2 different modes of operation for a hash table:
+**
+**   FTS3_HASH_STRING        pKey points to a string that is nKey bytes long
+**                           (including the null-terminator, if any).  Case
+**                           is respected in comparisons.
+**
+**   FTS3_HASH_BINARY        pKey points to binary data nKey bytes long. 
+**                           memcmp() is used to compare keys.
+**
+** A copy of the key is made if the copyKey parameter to fts3HashInit is 1.  
+*/
+#define FTS3_HASH_STRING    1
+#define FTS3_HASH_BINARY    2
+
+/*
+** Access routines.  To delete, insert a NULL pointer.
+*/
+SQLITE_PRIVATE void sqlite3Fts3HashInit(Fts3Hash *pNew, char keyClass, char copyKey);
+SQLITE_PRIVATE void *sqlite3Fts3HashInsert(Fts3Hash*, const void *pKey, int nKey, void *pData);
+SQLITE_PRIVATE void *sqlite3Fts3HashFind(const Fts3Hash*, const void *pKey, int nKey);
+SQLITE_PRIVATE void sqlite3Fts3HashClear(Fts3Hash*);
+SQLITE_PRIVATE Fts3HashElem *sqlite3Fts3HashFindElem(const Fts3Hash *, const void *, int);
+
+/*
+** Shorthand for the functions above
+*/
+#define fts3HashInit     sqlite3Fts3HashInit
+#define fts3HashInsert   sqlite3Fts3HashInsert
+#define fts3HashFind     sqlite3Fts3HashFind
+#define fts3HashClear    sqlite3Fts3HashClear
+#define fts3HashFindElem sqlite3Fts3HashFindElem
+
+/*
+** Macros for looping over all elements of a hash table.  The idiom is
+** like this:
+**
+**   Fts3Hash h;
+**   Fts3HashElem *p;
+**   ...
+**   for(p=fts3HashFirst(&h); p; p=fts3HashNext(p)){
+**     SomeStructure *pData = fts3HashData(p);
+**     // do something with pData
+**   }
+*/
+#define fts3HashFirst(H)  ((H)->first)
+#define fts3HashNext(E)   ((E)->next)
+#define fts3HashData(E)   ((E)->data)
+#define fts3HashKey(E)    ((E)->pKey)
+#define fts3HashKeysize(E) ((E)->nKey)
+
+/*
+** Number of entries in a hash table
+*/
+#define fts3HashCount(H)  ((H)->count)
+
+#endif /* _FTS3_HASH_H_ */
+
+/************** End of fts3_hash.h *******************************************/
+/************** Continuing where we left off in fts3Int.h ********************/
+
+/*
+** This constant determines the maximum depth of an FTS expression tree
+** that the library will create and use. FTS uses recursion to perform 
+** various operations on the query tree, so the disadvantage of a large
+** limit is that it may allow very large queries to use large amounts
+** of stack space (perhaps causing a stack overflow).
+*/
+#ifndef SQLITE_FTS3_MAX_EXPR_DEPTH
+# define SQLITE_FTS3_MAX_EXPR_DEPTH 12
+#endif
+
+
+/*
+** This constant controls how often segments are merged. Once there are
+** FTS3_MERGE_COUNT segments of level N, they are merged into a single
+** segment of level N+1.
+*/
+#define FTS3_MERGE_COUNT 16
+
+/*
+** This is the maximum amount of data (in bytes) to store in the 
+** Fts3Table.pendingTerms hash table. Normally, the hash table is
+** populated as documents are inserted/updated/deleted in a transaction
+** and used to create a new segment when the transaction is committed.
+** However if this limit is reached midway through a transaction, a new 
+** segment is created and the hash table cleared immediately.
+*/
+#define FTS3_MAX_PENDING_DATA (1*1024*1024)
+
+/*
+** Macro to return the number of elements in an array. SQLite has a
+** similar macro called ArraySize(). Use a different name to avoid
+** a collision when building an amalgamation with built-in FTS3.
+*/
+#define SizeofArray(X) ((int)(sizeof(X)/sizeof(X[0])))
+
+
+#ifndef MIN
+# define MIN(x,y) ((x)<(y)?(x):(y))
+#endif
+#ifndef MAX
+# define MAX(x,y) ((x)>(y)?(x):(y))
+#endif
+
+/*
+** Maximum length of a varint encoded integer. The varint format is different
+** from that used by SQLite, so the maximum length is 10, not 9.
+*/
+#define FTS3_VARINT_MAX 10
+
+/*
+** FTS4 virtual tables may maintain multiple indexes - one index of all terms
+** in the document set and zero or more prefix indexes. All indexes are stored
+** as one or more b+-trees in the %_segments and %_segdir tables. 
+**
+** It is possible to determine which index a b+-tree belongs to based on the
+** value stored in the "%_segdir.level" column. Given this value L, the index
+** that the b+-tree belongs to is (L<<10). In other words, all b+-trees with
+** level values between 0 and 1023 (inclusive) belong to index 0, all levels
+** between 1024 and 2047 to index 1, and so on.
+**
+** It is considered impossible for an index to use more than 1024 levels. In 
+** theory though this may happen, but only after at least 
+** (FTS3_MERGE_COUNT^1024) separate flushes of the pending-terms tables.
+*/
+#define FTS3_SEGDIR_MAXLEVEL      1024
+#define FTS3_SEGDIR_MAXLEVEL_STR "1024"
+
+/*
+** The testcase() macro is only used by the amalgamation.  If undefined,
+** make it a no-op.
+*/
+#ifndef testcase
+# define testcase(X)
+#endif
+
+/*
+** Terminator values for position-lists and column-lists.
+*/
+#define POS_COLUMN  (1)     /* Column-list terminator */
+#define POS_END     (0)     /* Position-list terminator */ 
+
+/*
+** This section provides definitions to allow the
+** FTS3 extension to be compiled outside of the 
+** amalgamation.
+*/
+#ifndef SQLITE_AMALGAMATION
+/*
+** Macros indicating that conditional expressions are always true or
+** false.
+*/
+#ifdef SQLITE_COVERAGE_TEST
+# define ALWAYS(x) (1)
+# define NEVER(X)  (0)
+#elif defined(SQLITE_DEBUG)
+# define ALWAYS(x) sqlite3Fts3Always((x)!=0)
+# define NEVER(x) sqlite3Fts3Never((x)!=0)
+SQLITE_PRIVATE int sqlite3Fts3Always(int b);
+SQLITE_PRIVATE int sqlite3Fts3Never(int b);
+#else
+# define ALWAYS(x) (x)
+# define NEVER(x)  (x)
+#endif
+
+/*
+** Internal types used by SQLite.
+*/
+typedef unsigned char u8;         /* 1-byte (or larger) unsigned integer */
+typedef short int i16;            /* 2-byte (or larger) signed integer */
+typedef unsigned int u32;         /* 4-byte unsigned integer */
+typedef sqlite3_uint64 u64;       /* 8-byte unsigned integer */
+typedef sqlite3_int64 i64;        /* 8-byte signed integer */
+
+/*
+** Macro used to suppress compiler warnings for unused parameters.
+*/
+#define UNUSED_PARAMETER(x) (void)(x)
+
+/*
+** Activate assert() only if SQLITE_TEST is enabled.
+*/
+#if !defined(NDEBUG) && !defined(SQLITE_DEBUG) 
+# define NDEBUG 1
+#endif
+
+/*
+** The TESTONLY macro is used to enclose variable declarations or
+** other bits of code that are needed to support the arguments
+** within testcase() and assert() macros.
+*/
+#if defined(SQLITE_DEBUG) || defined(SQLITE_COVERAGE_TEST)
+# define TESTONLY(X)  X
+#else
+# define TESTONLY(X)
+#endif
+
+#endif /* SQLITE_AMALGAMATION */
+
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE int sqlite3Fts3Corrupt(void);
+# define FTS_CORRUPT_VTAB sqlite3Fts3Corrupt()
+#else
+# define FTS_CORRUPT_VTAB SQLITE_CORRUPT_VTAB
+#endif
+
+typedef struct Fts3Table Fts3Table;
+typedef struct Fts3Cursor Fts3Cursor;
+typedef struct Fts3Expr Fts3Expr;
+typedef struct Fts3Phrase Fts3Phrase;
+typedef struct Fts3PhraseToken Fts3PhraseToken;
+
+typedef struct Fts3Doclist Fts3Doclist;
+typedef struct Fts3SegFilter Fts3SegFilter;
+typedef struct Fts3DeferredToken Fts3DeferredToken;
+typedef struct Fts3SegReader Fts3SegReader;
+typedef struct Fts3MultiSegReader Fts3MultiSegReader;
+
+typedef struct MatchinfoBuffer MatchinfoBuffer;
+
+/*
+** A connection to a fulltext index is an instance of the following
+** structure. The xCreate and xConnect methods create an instance
+** of this structure and xDestroy and xDisconnect free that instance.
+** All other methods receive a pointer to the structure as one of their
+** arguments.
+*/
+struct Fts3Table {
+  sqlite3_vtab base;              /* Base class used by SQLite core */
+  sqlite3 *db;                    /* The database connection */
+  const char *zDb;                /* logical database name */
+  const char *zName;              /* virtual table name */
+  int nColumn;                    /* number of named columns in virtual table */
+  char **azColumn;                /* column names.  malloced */
+  u8 *abNotindexed;               /* True for 'notindexed' columns */
+  sqlite3_tokenizer *pTokenizer;  /* tokenizer for inserts and queries */
+  char *zContentTbl;              /* content=xxx option, or NULL */
+  char *zLanguageid;              /* languageid=xxx option, or NULL */
+  int nAutoincrmerge;             /* Value configured by 'automerge' */
+  u32 nLeafAdd;                   /* Number of leaf blocks added this trans */
+
+  /* Precompiled statements used by the implementation. Each of these 
+  ** statements is run and reset within a single virtual table API call. 
+  */
+  sqlite3_stmt *aStmt[40];
+
+  char *zReadExprlist;
+  char *zWriteExprlist;
+
+  int nNodeSize;                  /* Soft limit for node size */
+  u8 bFts4;                       /* True for FTS4, false for FTS3 */
+  u8 bHasStat;                    /* True if %_stat table exists (2==unknown) */
+  u8 bHasDocsize;                 /* True if %_docsize table exists */
+  u8 bDescIdx;                    /* True if doclists are in reverse order */
+  u8 bIgnoreSavepoint;            /* True to ignore xSavepoint invocations */
+  int nPgsz;                      /* Page size for host database */
+  char *zSegmentsTbl;             /* Name of %_segments table */
+  sqlite3_blob *pSegments;        /* Blob handle open on %_segments table */
+
+  /* 
+  ** The following array of hash tables is used to buffer pending index 
+  ** updates during transactions. All pending updates buffered at any one
+  ** time must share a common language-id (see the FTS4 langid= feature).
+  ** The current language id is stored in variable iPrevLangid.
+  **
+  ** A single FTS4 table may have multiple full-text indexes. For each index
+  ** there is an entry in the aIndex[] array. Index 0 is an index of all the
+  ** terms that appear in the document set. Each subsequent index in aIndex[]
+  ** is an index of prefixes of a specific length.
+  **
+  ** Variable nPendingData contains an estimate the memory consumed by the 
+  ** pending data structures, including hash table overhead, but not including
+  ** malloc overhead.  When nPendingData exceeds nMaxPendingData, all hash
+  ** tables are flushed to disk. Variable iPrevDocid is the docid of the most 
+  ** recently inserted record.
+  */
+  int nIndex;                     /* Size of aIndex[] */
+  struct Fts3Index {
+    int nPrefix;                  /* Prefix length (0 for main terms index) */
+    Fts3Hash hPending;            /* Pending terms table for this index */
+  } *aIndex;
+  int nMaxPendingData;            /* Max pending data before flush to disk */
+  int nPendingData;               /* Current bytes of pending data */
+  sqlite_int64 iPrevDocid;        /* Docid of most recently inserted document */
+  int iPrevLangid;                /* Langid of recently inserted document */
+  int bPrevDelete;                /* True if last operation was a delete */
+
+#if defined(SQLITE_DEBUG) || defined(SQLITE_COVERAGE_TEST)
+  /* State variables used for validating that the transaction control
+  ** methods of the virtual table are called at appropriate times.  These
+  ** values do not contribute to FTS functionality; they are used for
+  ** verifying the operation of the SQLite core.
+  */
+  int inTransaction;     /* True after xBegin but before xCommit/xRollback */
+  int mxSavepoint;       /* Largest valid xSavepoint integer */
+#endif
+
+#ifdef SQLITE_TEST
+  /* True to disable the incremental doclist optimization. This is controled
+  ** by special insert command 'test-no-incr-doclist'.  */
+  int bNoIncrDoclist;
+#endif
+};
+
+/*
+** When the core wants to read from the virtual table, it creates a
+** virtual table cursor (an instance of the following structure) using
+** the xOpen method. Cursors are destroyed using the xClose method.
+*/
+struct Fts3Cursor {
+  sqlite3_vtab_cursor base;       /* Base class used by SQLite core */
+  i16 eSearch;                    /* Search strategy (see below) */
+  u8 isEof;                       /* True if at End Of Results */
+  u8 isRequireSeek;               /* True if must seek pStmt to %_content row */
+  sqlite3_stmt *pStmt;            /* Prepared statement in use by the cursor */
+  Fts3Expr *pExpr;                /* Parsed MATCH query string */
+  int iLangid;                    /* Language being queried for */
+  int nPhrase;                    /* Number of matchable phrases in query */
+  Fts3DeferredToken *pDeferred;   /* Deferred search tokens, if any */
+  sqlite3_int64 iPrevId;          /* Previous id read from aDoclist */
+  char *pNextId;                  /* Pointer into the body of aDoclist */
+  char *aDoclist;                 /* List of docids for full-text queries */
+  int nDoclist;                   /* Size of buffer at aDoclist */
+  u8 bDesc;                       /* True to sort in descending order */
+  int eEvalmode;                  /* An FTS3_EVAL_XX constant */
+  int nRowAvg;                    /* Average size of database rows, in pages */
+  sqlite3_int64 nDoc;             /* Documents in table */
+  i64 iMinDocid;                  /* Minimum docid to return */
+  i64 iMaxDocid;                  /* Maximum docid to return */
+  int isMatchinfoNeeded;          /* True when aMatchinfo[] needs filling in */
+  MatchinfoBuffer *pMIBuffer;     /* Buffer for matchinfo data */
+};
+
+#define FTS3_EVAL_FILTER    0
+#define FTS3_EVAL_NEXT      1
+#define FTS3_EVAL_MATCHINFO 2
+
+/*
+** The Fts3Cursor.eSearch member is always set to one of the following.
+** Actualy, Fts3Cursor.eSearch can be greater than or equal to
+** FTS3_FULLTEXT_SEARCH.  If so, then Fts3Cursor.eSearch - 2 is the index
+** of the column to be searched.  For example, in
+**
+**     CREATE VIRTUAL TABLE ex1 USING fts3(a,b,c,d);
+**     SELECT docid FROM ex1 WHERE b MATCH 'one two three';
+** 
+** Because the LHS of the MATCH operator is 2nd column "b",
+** Fts3Cursor.eSearch will be set to FTS3_FULLTEXT_SEARCH+1.  (+0 for a,
+** +1 for b, +2 for c, +3 for d.)  If the LHS of MATCH were "ex1" 
+** indicating that all columns should be searched,
+** then eSearch would be set to FTS3_FULLTEXT_SEARCH+4.
+*/
+#define FTS3_FULLSCAN_SEARCH 0    /* Linear scan of %_content table */
+#define FTS3_DOCID_SEARCH    1    /* Lookup by rowid on %_content table */
+#define FTS3_FULLTEXT_SEARCH 2    /* Full-text index search */
+
+/*
+** The lower 16-bits of the sqlite3_index_info.idxNum value set by
+** the xBestIndex() method contains the Fts3Cursor.eSearch value described
+** above. The upper 16-bits contain a combination of the following
+** bits, used to describe extra constraints on full-text searches.
+*/
+#define FTS3_HAVE_LANGID    0x00010000      /* languageid=? */
+#define FTS3_HAVE_DOCID_GE  0x00020000      /* docid>=? */
+#define FTS3_HAVE_DOCID_LE  0x00040000      /* docid<=? */
+
+struct Fts3Doclist {
+  char *aAll;                    /* Array containing doclist (or NULL) */
+  int nAll;                      /* Size of a[] in bytes */
+  char *pNextDocid;              /* Pointer to next docid */
+
+  sqlite3_int64 iDocid;          /* Current docid (if pList!=0) */
+  int bFreeList;                 /* True if pList should be sqlite3_free()d */
+  char *pList;                   /* Pointer to position list following iDocid */
+  int nList;                     /* Length of position list */
+};
+
+/*
+** A "phrase" is a sequence of one or more tokens that must match in
+** sequence.  A single token is the base case and the most common case.
+** For a sequence of tokens contained in double-quotes (i.e. "one two three")
+** nToken will be the number of tokens in the string.
+*/
+struct Fts3PhraseToken {
+  char *z;                        /* Text of the token */
+  int n;                          /* Number of bytes in buffer z */
+  int isPrefix;                   /* True if token ends with a "*" character */
+  int bFirst;                     /* True if token must appear at position 0 */
+
+  /* Variables above this point are populated when the expression is
+  ** parsed (by code in fts3_expr.c). Below this point the variables are
+  ** used when evaluating the expression. */
+  Fts3DeferredToken *pDeferred;   /* Deferred token object for this token */
+  Fts3MultiSegReader *pSegcsr;    /* Segment-reader for this token */
+};
+
+struct Fts3Phrase {
+  /* Cache of doclist for this phrase. */
+  Fts3Doclist doclist;
+  int bIncr;                 /* True if doclist is loaded incrementally */
+  int iDoclistToken;
+
+  /* Used by sqlite3Fts3EvalPhrasePoslist() if this is a descendent of an
+  ** OR condition.  */
+  char *pOrPoslist;
+  i64 iOrDocid;
+
+  /* Variables below this point are populated by fts3_expr.c when parsing 
+  ** a MATCH expression. Everything above is part of the evaluation phase. 
+  */
+  int nToken;                /* Number of tokens in the phrase */
+  int iColumn;               /* Index of column this phrase must match */
+  Fts3PhraseToken aToken[1]; /* One entry for each token in the phrase */
+};
+
+/*
+** A tree of these objects forms the RHS of a MATCH operator.
+**
+** If Fts3Expr.eType is FTSQUERY_PHRASE and isLoaded is true, then aDoclist 
+** points to a malloced buffer, size nDoclist bytes, containing the results 
+** of this phrase query in FTS3 doclist format. As usual, the initial 
+** "Length" field found in doclists stored on disk is omitted from this 
+** buffer.
+**
+** Variable aMI is used only for FTSQUERY_NEAR nodes to store the global
+** matchinfo data. If it is not NULL, it points to an array of size nCol*3,
+** where nCol is the number of columns in the queried FTS table. The array
+** is populated as follows:
+**
+**   aMI[iCol*3 + 0] = Undefined
+**   aMI[iCol*3 + 1] = Number of occurrences
+**   aMI[iCol*3 + 2] = Number of rows containing at least one instance
+**
+** The aMI array is allocated using sqlite3_malloc(). It should be freed 
+** when the expression node is.
+*/
+struct Fts3Expr {
+  int eType;                 /* One of the FTSQUERY_XXX values defined below */
+  int nNear;                 /* Valid if eType==FTSQUERY_NEAR */
+  Fts3Expr *pParent;         /* pParent->pLeft==this or pParent->pRight==this */
+  Fts3Expr *pLeft;           /* Left operand */
+  Fts3Expr *pRight;          /* Right operand */
+  Fts3Phrase *pPhrase;       /* Valid if eType==FTSQUERY_PHRASE */
+
+  /* The following are used by the fts3_eval.c module. */
+  sqlite3_int64 iDocid;      /* Current docid */
+  u8 bEof;                   /* True this expression is at EOF already */
+  u8 bStart;                 /* True if iDocid is valid */
+  u8 bDeferred;              /* True if this expression is entirely deferred */
+
+  /* The following are used by the fts3_snippet.c module. */
+  int iPhrase;               /* Index of this phrase in matchinfo() results */
+  u32 *aMI;                  /* See above */
+};
+
+/*
+** Candidate values for Fts3Query.eType. Note that the order of the first
+** four values is in order of precedence when parsing expressions. For 
+** example, the following:
+**
+**   "a OR b AND c NOT d NEAR e"
+**
+** is equivalent to:
+**
+**   "a OR (b AND (c NOT (d NEAR e)))"
+*/
+#define FTSQUERY_NEAR   1
+#define FTSQUERY_NOT    2
+#define FTSQUERY_AND    3
+#define FTSQUERY_OR     4
+#define FTSQUERY_PHRASE 5
+
+
+/* fts3_write.c */
+SQLITE_PRIVATE int sqlite3Fts3UpdateMethod(sqlite3_vtab*,int,sqlite3_value**,sqlite3_int64*);
+SQLITE_PRIVATE int sqlite3Fts3PendingTermsFlush(Fts3Table *);
+SQLITE_PRIVATE void sqlite3Fts3PendingTermsClear(Fts3Table *);
+SQLITE_PRIVATE int sqlite3Fts3Optimize(Fts3Table *);
+SQLITE_PRIVATE int sqlite3Fts3SegReaderNew(int, int, sqlite3_int64,
+  sqlite3_int64, sqlite3_int64, const char *, int, Fts3SegReader**);
+SQLITE_PRIVATE int sqlite3Fts3SegReaderPending(
+  Fts3Table*,int,const char*,int,int,Fts3SegReader**);
+SQLITE_PRIVATE void sqlite3Fts3SegReaderFree(Fts3SegReader *);
+SQLITE_PRIVATE int sqlite3Fts3AllSegdirs(Fts3Table*, int, int, int, sqlite3_stmt **);
+SQLITE_PRIVATE int sqlite3Fts3ReadBlock(Fts3Table*, sqlite3_int64, char **, int*, int*);
+
+SQLITE_PRIVATE int sqlite3Fts3SelectDoctotal(Fts3Table *, sqlite3_stmt **);
+SQLITE_PRIVATE int sqlite3Fts3SelectDocsize(Fts3Table *, sqlite3_int64, sqlite3_stmt **);
+
+#ifndef SQLITE_DISABLE_FTS4_DEFERRED
+SQLITE_PRIVATE void sqlite3Fts3FreeDeferredTokens(Fts3Cursor *);
+SQLITE_PRIVATE int sqlite3Fts3DeferToken(Fts3Cursor *, Fts3PhraseToken *, int);
+SQLITE_PRIVATE int sqlite3Fts3CacheDeferredDoclists(Fts3Cursor *);
+SQLITE_PRIVATE void sqlite3Fts3FreeDeferredDoclists(Fts3Cursor *);
+SQLITE_PRIVATE int sqlite3Fts3DeferredTokenList(Fts3DeferredToken *, char **, int *);
+#else
+# define sqlite3Fts3FreeDeferredTokens(x)
+# define sqlite3Fts3DeferToken(x,y,z) SQLITE_OK
+# define sqlite3Fts3CacheDeferredDoclists(x) SQLITE_OK
+# define sqlite3Fts3FreeDeferredDoclists(x)
+# define sqlite3Fts3DeferredTokenList(x,y,z) SQLITE_OK
+#endif
+
+SQLITE_PRIVATE void sqlite3Fts3SegmentsClose(Fts3Table *);
+SQLITE_PRIVATE int sqlite3Fts3MaxLevel(Fts3Table *, int *);
+
+/* Special values interpreted by sqlite3SegReaderCursor() */
+#define FTS3_SEGCURSOR_PENDING        -1
+#define FTS3_SEGCURSOR_ALL            -2
+
+SQLITE_PRIVATE int sqlite3Fts3SegReaderStart(Fts3Table*, Fts3MultiSegReader*, Fts3SegFilter*);
+SQLITE_PRIVATE int sqlite3Fts3SegReaderStep(Fts3Table *, Fts3MultiSegReader *);
+SQLITE_PRIVATE void sqlite3Fts3SegReaderFinish(Fts3MultiSegReader *);
+
+SQLITE_PRIVATE int sqlite3Fts3SegReaderCursor(Fts3Table *, 
+    int, int, int, const char *, int, int, int, Fts3MultiSegReader *);
+
+/* Flags allowed as part of the 4th argument to SegmentReaderIterate() */
+#define FTS3_SEGMENT_REQUIRE_POS   0x00000001
+#define FTS3_SEGMENT_IGNORE_EMPTY  0x00000002
+#define FTS3_SEGMENT_COLUMN_FILTER 0x00000004
+#define FTS3_SEGMENT_PREFIX        0x00000008
+#define FTS3_SEGMENT_SCAN          0x00000010
+#define FTS3_SEGMENT_FIRST         0x00000020
+
+/* Type passed as 4th argument to SegmentReaderIterate() */
+struct Fts3SegFilter {
+  const char *zTerm;
+  int nTerm;
+  int iCol;
+  int flags;
+};
+
+struct Fts3MultiSegReader {
+  /* Used internally by sqlite3Fts3SegReaderXXX() calls */
+  Fts3SegReader **apSegment;      /* Array of Fts3SegReader objects */
+  int nSegment;                   /* Size of apSegment array */
+  int nAdvance;                   /* How many seg-readers to advance */
+  Fts3SegFilter *pFilter;         /* Pointer to filter object */
+  char *aBuffer;                  /* Buffer to merge doclists in */
+  int nBuffer;                    /* Allocated size of aBuffer[] in bytes */
+
+  int iColFilter;                 /* If >=0, filter for this column */
+  int bRestart;
+
+  /* Used by fts3.c only. */
+  int nCost;                      /* Cost of running iterator */
+  int bLookup;                    /* True if a lookup of a single entry. */
+
+  /* Output values. Valid only after Fts3SegReaderStep() returns SQLITE_ROW. */
+  char *zTerm;                    /* Pointer to term buffer */
+  int nTerm;                      /* Size of zTerm in bytes */
+  char *aDoclist;                 /* Pointer to doclist buffer */
+  int nDoclist;                   /* Size of aDoclist[] in bytes */
+};
+
+SQLITE_PRIVATE int sqlite3Fts3Incrmerge(Fts3Table*,int,int);
+
+#define fts3GetVarint32(p, piVal) (                                           \
+  (*(u8*)(p)&0x80) ? sqlite3Fts3GetVarint32(p, piVal) : (*piVal=*(u8*)(p), 1) \
+)
+
+/* fts3.c */
+SQLITE_PRIVATE void sqlite3Fts3ErrMsg(char**,const char*,...);
+SQLITE_PRIVATE int sqlite3Fts3PutVarint(char *, sqlite3_int64);
+SQLITE_PRIVATE int sqlite3Fts3GetVarint(const char *, sqlite_int64 *);
+SQLITE_PRIVATE int sqlite3Fts3GetVarint32(const char *, int *);
+SQLITE_PRIVATE int sqlite3Fts3VarintLen(sqlite3_uint64);
+SQLITE_PRIVATE void sqlite3Fts3Dequote(char *);
+SQLITE_PRIVATE void sqlite3Fts3DoclistPrev(int,char*,int,char**,sqlite3_int64*,int*,u8*);
+SQLITE_PRIVATE int sqlite3Fts3EvalPhraseStats(Fts3Cursor *, Fts3Expr *, u32 *);
+SQLITE_PRIVATE int sqlite3Fts3FirstFilter(sqlite3_int64, char *, int, char *);
+SQLITE_PRIVATE void sqlite3Fts3CreateStatTable(int*, Fts3Table*);
+SQLITE_PRIVATE int sqlite3Fts3EvalTestDeferred(Fts3Cursor *pCsr, int *pRc);
+
+/* fts3_tokenizer.c */
+SQLITE_PRIVATE const char *sqlite3Fts3NextToken(const char *, int *);
+SQLITE_PRIVATE int sqlite3Fts3InitHashTable(sqlite3 *, Fts3Hash *, const char *);
+SQLITE_PRIVATE int sqlite3Fts3InitTokenizer(Fts3Hash *pHash, const char *, 
+    sqlite3_tokenizer **, char **
+);
+SQLITE_PRIVATE int sqlite3Fts3IsIdChar(char);
+
+/* fts3_snippet.c */
+SQLITE_PRIVATE void sqlite3Fts3Offsets(sqlite3_context*, Fts3Cursor*);
+SQLITE_PRIVATE void sqlite3Fts3Snippet(sqlite3_context *, Fts3Cursor *, const char *,
+  const char *, const char *, int, int
+);
+SQLITE_PRIVATE void sqlite3Fts3Matchinfo(sqlite3_context *, Fts3Cursor *, const char *);
+SQLITE_PRIVATE void sqlite3Fts3MIBufferFree(MatchinfoBuffer *p);
+
+/* fts3_expr.c */
+SQLITE_PRIVATE int sqlite3Fts3ExprParse(sqlite3_tokenizer *, int,
+  char **, int, int, int, const char *, int, Fts3Expr **, char **
+);
+SQLITE_PRIVATE void sqlite3Fts3ExprFree(Fts3Expr *);
+#ifdef SQLITE_TEST
+SQLITE_PRIVATE int sqlite3Fts3ExprInitTestInterface(sqlite3 *db);
+SQLITE_PRIVATE int sqlite3Fts3InitTerm(sqlite3 *db);
+#endif
+
+SQLITE_PRIVATE int sqlite3Fts3OpenTokenizer(sqlite3_tokenizer *, int, const char *, int,
+  sqlite3_tokenizer_cursor **
+);
+
+/* fts3_aux.c */
+SQLITE_PRIVATE int sqlite3Fts3InitAux(sqlite3 *db);
+
+SQLITE_PRIVATE void sqlite3Fts3EvalPhraseCleanup(Fts3Phrase *);
+
+SQLITE_PRIVATE int sqlite3Fts3MsrIncrStart(
+    Fts3Table*, Fts3MultiSegReader*, int, const char*, int);
+SQLITE_PRIVATE int sqlite3Fts3MsrIncrNext(
+    Fts3Table *, Fts3MultiSegReader *, sqlite3_int64 *, char **, int *);
+SQLITE_PRIVATE int sqlite3Fts3EvalPhrasePoslist(Fts3Cursor *, Fts3Expr *, int iCol, char **); 
+SQLITE_PRIVATE int sqlite3Fts3MsrOvfl(Fts3Cursor *, Fts3MultiSegReader *, int *);
+SQLITE_PRIVATE int sqlite3Fts3MsrIncrRestart(Fts3MultiSegReader *pCsr);
+
+/* fts3_tokenize_vtab.c */
+SQLITE_PRIVATE int sqlite3Fts3InitTok(sqlite3*, Fts3Hash *);
+
+/* fts3_unicode2.c (functions generated by parsing unicode text files) */
+#ifndef SQLITE_DISABLE_FTS3_UNICODE
+SQLITE_PRIVATE int sqlite3FtsUnicodeFold(int, int);
+SQLITE_PRIVATE int sqlite3FtsUnicodeIsalnum(int);
+SQLITE_PRIVATE int sqlite3FtsUnicodeIsdiacritic(int);
+#endif
+
+#endif /* !SQLITE_CORE || SQLITE_ENABLE_FTS3 */
+#endif /* _FTSINT_H */
+
+/************** End of fts3Int.h *********************************************/
+/************** Continuing where we left off in fts3.c ***********************/
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
+
+#if defined(SQLITE_ENABLE_FTS3) && !defined(SQLITE_CORE)
+# define SQLITE_CORE 1
+#endif
+
+/* #include <assert.h> */
+/* #include <stdlib.h> */
+/* #include <stddef.h> */
+/* #include <stdio.h> */
+/* #include <string.h> */
+/* #include <stdarg.h> */
+
+/* #include "fts3.h" */
+#ifndef SQLITE_CORE 
+/* # include "sqlite3ext.h" */
+  SQLITE_EXTENSION_INIT1
+#endif
+
+static int fts3EvalNext(Fts3Cursor *pCsr);
+static int fts3EvalStart(Fts3Cursor *pCsr);
+static int fts3TermSegReaderCursor(
+    Fts3Cursor *, const char *, int, int, Fts3MultiSegReader **);
+
+#ifndef SQLITE_AMALGAMATION
+# if defined(SQLITE_DEBUG)
+SQLITE_PRIVATE int sqlite3Fts3Always(int b) { assert( b ); return b; }
+SQLITE_PRIVATE int sqlite3Fts3Never(int b)  { assert( !b ); return b; }
+# endif
+#endif
+
+/* 
+** Write a 64-bit variable-length integer to memory starting at p[0].
+** The length of data written will be between 1 and FTS3_VARINT_MAX bytes.
+** The number of bytes written is returned.
+*/
+SQLITE_PRIVATE int sqlite3Fts3PutVarint(char *p, sqlite_int64 v){
+  unsigned char *q = (unsigned char *) p;
+  sqlite_uint64 vu = v;
+  do{
+    *q++ = (unsigned char) ((vu & 0x7f) | 0x80);
+    vu >>= 7;
+  }while( vu!=0 );
+  q[-1] &= 0x7f;  /* turn off high bit in final byte */
+  assert( q - (unsigned char *)p <= FTS3_VARINT_MAX );
+  return (int) (q - (unsigned char *)p);
+}
+
+#define GETVARINT_STEP(v, ptr, shift, mask1, mask2, var, ret) \
+  v = (v & mask1) | ( (*ptr++) << shift );                    \
+  if( (v & mask2)==0 ){ var = v; return ret; }
+#define GETVARINT_INIT(v, ptr, shift, mask1, mask2, var, ret) \
+  v = (*ptr++);                                               \
+  if( (v & mask2)==0 ){ var = v; return ret; }
+
+/* 
+** Read a 64-bit variable-length integer from memory starting at p[0].
+** Return the number of bytes read, or 0 on error.
+** The value is stored in *v.
+*/
+SQLITE_PRIVATE int sqlite3Fts3GetVarint(const char *p, sqlite_int64 *v){
+  const char *pStart = p;
+  u32 a;
+  u64 b;
+  int shift;
+
+  GETVARINT_INIT(a, p, 0,  0x00,     0x80, *v, 1);
+  GETVARINT_STEP(a, p, 7,  0x7F,     0x4000, *v, 2);
+  GETVARINT_STEP(a, p, 14, 0x3FFF,   0x200000, *v, 3);
+  GETVARINT_STEP(a, p, 21, 0x1FFFFF, 0x10000000, *v, 4);
+  b = (a & 0x0FFFFFFF );
+
+  for(shift=28; shift<=63; shift+=7){
+    u64 c = *p++;
+    b += (c&0x7F) << shift;
+    if( (c & 0x80)==0 ) break;
+  }
+  *v = b;
+  return (int)(p - pStart);
+}
+
+/*
+** Similar to sqlite3Fts3GetVarint(), except that the output is truncated to a
+** 32-bit integer before it is returned.
+*/
+SQLITE_PRIVATE int sqlite3Fts3GetVarint32(const char *p, int *pi){
+  u32 a;
+
+#ifndef fts3GetVarint32
+  GETVARINT_INIT(a, p, 0,  0x00,     0x80, *pi, 1);
+#else
+  a = (*p++);
+  assert( a & 0x80 );
+#endif
+
+  GETVARINT_STEP(a, p, 7,  0x7F,     0x4000, *pi, 2);
+  GETVARINT_STEP(a, p, 14, 0x3FFF,   0x200000, *pi, 3);
+  GETVARINT_STEP(a, p, 21, 0x1FFFFF, 0x10000000, *pi, 4);
+  a = (a & 0x0FFFFFFF );
+  *pi = (int)(a | ((u32)(*p & 0x0F) << 28));
+  return 5;
+}
+
+/*
+** Return the number of bytes required to encode v as a varint
+*/
+SQLITE_PRIVATE int sqlite3Fts3VarintLen(sqlite3_uint64 v){
+  int i = 0;
+  do{
+    i++;
+    v >>= 7;
+  }while( v!=0 );
+  return i;
+}
+
+/*
+** Convert an SQL-style quoted string into a normal string by removing
+** the quote characters.  The conversion is done in-place.  If the
+** input does not begin with a quote character, then this routine
+** is a no-op.
+**
+** Examples:
+**
+**     "abc"   becomes   abc
+**     'xyz'   becomes   xyz
+**     [pqr]   becomes   pqr
+**     `mno`   becomes   mno
+**
+*/
+SQLITE_PRIVATE void sqlite3Fts3Dequote(char *z){
+  char quote;                     /* Quote character (if any ) */
+
+  quote = z[0];
+  if( quote=='[' || quote=='\'' || quote=='"' || quote=='`' ){
+    int iIn = 1;                  /* Index of next byte to read from input */
+    int iOut = 0;                 /* Index of next byte to write to output */
+
+    /* If the first byte was a '[', then the close-quote character is a ']' */
+    if( quote=='[' ) quote = ']';  
+
+    while( z[iIn] ){
+      if( z[iIn]==quote ){
+        if( z[iIn+1]!=quote ) break;
+        z[iOut++] = quote;
+        iIn += 2;
+      }else{
+        z[iOut++] = z[iIn++];
+      }
+    }
+    z[iOut] = '\0';
+  }
+}
+
+/*
+** Read a single varint from the doclist at *pp and advance *pp to point
+** to the first byte past the end of the varint.  Add the value of the varint
+** to *pVal.
+*/
+static void fts3GetDeltaVarint(char **pp, sqlite3_int64 *pVal){
+  sqlite3_int64 iVal;
+  *pp += sqlite3Fts3GetVarint(*pp, &iVal);
+  *pVal += iVal;
+}
+
+/*
+** When this function is called, *pp points to the first byte following a
+** varint that is part of a doclist (or position-list, or any other list
+** of varints). This function moves *pp to point to the start of that varint,
+** and sets *pVal by the varint value.
+**
+** Argument pStart points to the first byte of the doclist that the
+** varint is part of.
+*/
+static void fts3GetReverseVarint(
+  char **pp, 
+  char *pStart, 
+  sqlite3_int64 *pVal
+){
+  sqlite3_int64 iVal;
+  char *p;
+
+  /* Pointer p now points at the first byte past the varint we are 
+  ** interested in. So, unless the doclist is corrupt, the 0x80 bit is
+  ** clear on character p[-1]. */
+  for(p = (*pp)-2; p>=pStart && *p&0x80; p--);
+  p++;
+  *pp = p;
+
+  sqlite3Fts3GetVarint(p, &iVal);
+  *pVal = iVal;
+}
+
+/*
+** The xDisconnect() virtual table method.
+*/
+static int fts3DisconnectMethod(sqlite3_vtab *pVtab){
+  Fts3Table *p = (Fts3Table *)pVtab;
+  int i;
+
+  assert( p->nPendingData==0 );
+  assert( p->pSegments==0 );
+
+  /* Free any prepared statements held */
+  for(i=0; i<SizeofArray(p->aStmt); i++){
+    sqlite3_finalize(p->aStmt[i]);
+  }
+  sqlite3_free(p->zSegmentsTbl);
+  sqlite3_free(p->zReadExprlist);
+  sqlite3_free(p->zWriteExprlist);
+  sqlite3_free(p->zContentTbl);
+  sqlite3_free(p->zLanguageid);
+
+  /* Invoke the tokenizer destructor to free the tokenizer. */
+  p->pTokenizer->pModule->xDestroy(p->pTokenizer);
+
+  sqlite3_free(p);
+  return SQLITE_OK;
+}
+
+/*
+** Write an error message into *pzErr
+*/
+SQLITE_PRIVATE void sqlite3Fts3ErrMsg(char **pzErr, const char *zFormat, ...){
+  va_list ap;
+  sqlite3_free(*pzErr);
+  va_start(ap, zFormat);
+  *pzErr = sqlite3_vmprintf(zFormat, ap);
+  va_end(ap);
+}
+
+/*
+** Construct one or more SQL statements from the format string given
+** and then evaluate those statements. The success code is written
+** into *pRc.
+**
+** If *pRc is initially non-zero then this routine is a no-op.
+*/
+static void fts3DbExec(
+  int *pRc,              /* Success code */
+  sqlite3 *db,           /* Database in which to run SQL */
+  const char *zFormat,   /* Format string for SQL */
+  ...                    /* Arguments to the format string */
+){
+  va_list ap;
+  char *zSql;
+  if( *pRc ) return;
+  va_start(ap, zFormat);
+  zSql = sqlite3_vmprintf(zFormat, ap);
+  va_end(ap);
+  if( zSql==0 ){
+    *pRc = SQLITE_NOMEM;
+  }else{
+    *pRc = sqlite3_exec(db, zSql, 0, 0, 0);
+    sqlite3_free(zSql);
+  }
+}
+
+/*
+** The xDestroy() virtual table method.
+*/
+static int fts3DestroyMethod(sqlite3_vtab *pVtab){
+  Fts3Table *p = (Fts3Table *)pVtab;
+  int rc = SQLITE_OK;              /* Return code */
+  const char *zDb = p->zDb;        /* Name of database (e.g. "main", "temp") */
+  sqlite3 *db = p->db;             /* Database handle */
+
+  /* Drop the shadow tables */
+  if( p->zContentTbl==0 ){
+    fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_content'", zDb, p->zName);
+  }
+  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_segments'", zDb,p->zName);
+  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_segdir'", zDb, p->zName);
+  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_docsize'", zDb, p->zName);
+  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_stat'", zDb, p->zName);
+
+  /* If everything has worked, invoke fts3DisconnectMethod() to free the
+  ** memory associated with the Fts3Table structure and return SQLITE_OK.
+  ** Otherwise, return an SQLite error code.
+  */
+  return (rc==SQLITE_OK ? fts3DisconnectMethod(pVtab) : rc);
+}
+
+
+/*
+** Invoke sqlite3_declare_vtab() to declare the schema for the FTS3 table
+** passed as the first argument. This is done as part of the xConnect()
+** and xCreate() methods.
+**
+** If *pRc is non-zero when this function is called, it is a no-op. 
+** Otherwise, if an error occurs, an SQLite error code is stored in *pRc
+** before returning.
+*/
+static void fts3DeclareVtab(int *pRc, Fts3Table *p){
+  if( *pRc==SQLITE_OK ){
+    int i;                        /* Iterator variable */
+    int rc;                       /* Return code */
+    char *zSql;                   /* SQL statement passed to declare_vtab() */
+    char *zCols;                  /* List of user defined columns */
+    const char *zLanguageid;
+
+    zLanguageid = (p->zLanguageid ? p->zLanguageid : "__langid");
+    sqlite3_vtab_config(p->db, SQLITE_VTAB_CONSTRAINT_SUPPORT, 1);
+
+    /* Create a list of user columns for the virtual table */
+    zCols = sqlite3_mprintf("%Q, ", p->azColumn[0]);
+    for(i=1; zCols && i<p->nColumn; i++){
+      zCols = sqlite3_mprintf("%z%Q, ", zCols, p->azColumn[i]);
+    }
+
+    /* Create the whole "CREATE TABLE" statement to pass to SQLite */
+    zSql = sqlite3_mprintf(
+        "CREATE TABLE x(%s %Q HIDDEN, docid HIDDEN, %Q HIDDEN)", 
+        zCols, p->zName, zLanguageid
+    );
+    if( !zCols || !zSql ){
+      rc = SQLITE_NOMEM;
+    }else{
+      rc = sqlite3_declare_vtab(p->db, zSql);
+    }
+
+    sqlite3_free(zSql);
+    sqlite3_free(zCols);
+    *pRc = rc;
+  }
+}
+
+/*
+** Create the %_stat table if it does not already exist.
+*/
+SQLITE_PRIVATE void sqlite3Fts3CreateStatTable(int *pRc, Fts3Table *p){
+  fts3DbExec(pRc, p->db, 
+      "CREATE TABLE IF NOT EXISTS %Q.'%q_stat'"
+          "(id INTEGER PRIMARY KEY, value BLOB);",
+      p->zDb, p->zName
+  );
+  if( (*pRc)==SQLITE_OK ) p->bHasStat = 1;
+}
+
+/*
+** Create the backing store tables (%_content, %_segments and %_segdir)
+** required by the FTS3 table passed as the only argument. This is done
+** as part of the vtab xCreate() method.
+**
+** If the p->bHasDocsize boolean is true (indicating that this is an
+** FTS4 table, not an FTS3 table) then also create the %_docsize and
+** %_stat tables required by FTS4.
+*/
+static int fts3CreateTables(Fts3Table *p){
+  int rc = SQLITE_OK;             /* Return code */
+  int i;                          /* Iterator variable */
+  sqlite3 *db = p->db;            /* The database connection */
+
+  if( p->zContentTbl==0 ){
+    const char *zLanguageid = p->zLanguageid;
+    char *zContentCols;           /* Columns of %_content table */
+
+    /* Create a list of user columns for the content table */
+    zContentCols = sqlite3_mprintf("docid INTEGER PRIMARY KEY");
+    for(i=0; zContentCols && i<p->nColumn; i++){
+      char *z = p->azColumn[i];
+      zContentCols = sqlite3_mprintf("%z, 'c%d%q'", zContentCols, i, z);
+    }
+    if( zLanguageid && zContentCols ){
+      zContentCols = sqlite3_mprintf("%z, langid", zContentCols, zLanguageid);
+    }
+    if( zContentCols==0 ) rc = SQLITE_NOMEM;
+  
+    /* Create the content table */
+    fts3DbExec(&rc, db, 
+       "CREATE TABLE %Q.'%q_content'(%s)",
+       p->zDb, p->zName, zContentCols
+    );
+    sqlite3_free(zContentCols);
+  }
+
+  /* Create other tables */
+  fts3DbExec(&rc, db, 
+      "CREATE TABLE %Q.'%q_segments'(blockid INTEGER PRIMARY KEY, block BLOB);",
+      p->zDb, p->zName
+  );
+  fts3DbExec(&rc, db, 
+      "CREATE TABLE %Q.'%q_segdir'("
+        "level INTEGER,"
+        "idx INTEGER,"
+        "start_block INTEGER,"
+        "leaves_end_block INTEGER,"
+        "end_block INTEGER,"
+        "root BLOB,"
+        "PRIMARY KEY(level, idx)"
+      ");",
+      p->zDb, p->zName
+  );
+  if( p->bHasDocsize ){
+    fts3DbExec(&rc, db, 
+        "CREATE TABLE %Q.'%q_docsize'(docid INTEGER PRIMARY KEY, size BLOB);",
+        p->zDb, p->zName
+    );
+  }
+  assert( p->bHasStat==p->bFts4 );
+  if( p->bHasStat ){
+    sqlite3Fts3CreateStatTable(&rc, p);
+  }
+  return rc;
+}
+
+/*
+** Store the current database page-size in bytes in p->nPgsz.
+**
+** If *pRc is non-zero when this function is called, it is a no-op. 
+** Otherwise, if an error occurs, an SQLite error code is stored in *pRc
+** before returning.
+*/
+static void fts3DatabasePageSize(int *pRc, Fts3Table *p){
+  if( *pRc==SQLITE_OK ){
+    int rc;                       /* Return code */
+    char *zSql;                   /* SQL text "PRAGMA %Q.page_size" */
+    sqlite3_stmt *pStmt;          /* Compiled "PRAGMA %Q.page_size" statement */
+  
+    zSql = sqlite3_mprintf("PRAGMA %Q.page_size", p->zDb);
+    if( !zSql ){
+      rc = SQLITE_NOMEM;
+    }else{
+      rc = sqlite3_prepare(p->db, zSql, -1, &pStmt, 0);
+      if( rc==SQLITE_OK ){
+        sqlite3_step(pStmt);
+        p->nPgsz = sqlite3_column_int(pStmt, 0);
+        rc = sqlite3_finalize(pStmt);
+      }else if( rc==SQLITE_AUTH ){
+        p->nPgsz = 1024;
+        rc = SQLITE_OK;
+      }
+    }
+    assert( p->nPgsz>0 || rc!=SQLITE_OK );
+    sqlite3_free(zSql);
+    *pRc = rc;
+  }
+}
+
+/*
+** "Special" FTS4 arguments are column specifications of the following form:
+**
+**   <key> = <value>
+**
+** There may not be whitespace surrounding the "=" character. The <value> 
+** term may be quoted, but the <key> may not.
+*/
+static int fts3IsSpecialColumn(
+  const char *z, 
+  int *pnKey,
+  char **pzValue
+){
+  char *zValue;
+  const char *zCsr = z;
+
+  while( *zCsr!='=' ){
+    if( *zCsr=='\0' ) return 0;
+    zCsr++;
+  }
+
+  *pnKey = (int)(zCsr-z);
+  zValue = sqlite3_mprintf("%s", &zCsr[1]);
+  if( zValue ){
+    sqlite3Fts3Dequote(zValue);
+  }
+  *pzValue = zValue;
+  return 1;
+}
+
+/*
+** Append the output of a printf() style formatting to an existing string.
+*/
+static void fts3Appendf(
+  int *pRc,                       /* IN/OUT: Error code */
+  char **pz,                      /* IN/OUT: Pointer to string buffer */
+  const char *zFormat,            /* Printf format string to append */
+  ...                             /* Arguments for printf format string */
+){
+  if( *pRc==SQLITE_OK ){
+    va_list ap;
+    char *z;
+    va_start(ap, zFormat);
+    z = sqlite3_vmprintf(zFormat, ap);
+    va_end(ap);
+    if( z && *pz ){
+      char *z2 = sqlite3_mprintf("%s%s", *pz, z);
+      sqlite3_free(z);
+      z = z2;
+    }
+    if( z==0 ) *pRc = SQLITE_NOMEM;
+    sqlite3_free(*pz);
+    *pz = z;
+  }
+}
+
+/*
+** Return a copy of input string zInput enclosed in double-quotes (") and
+** with all double quote characters escaped. For example:
+**
+**     fts3QuoteId("un \"zip\"")   ->    "un \"\"zip\"\""
+**
+** The pointer returned points to memory obtained from sqlite3_malloc(). It
+** is the callers responsibility to call sqlite3_free() to release this
+** memory.
+*/
+static char *fts3QuoteId(char const *zInput){
+  int nRet;
+  char *zRet;
+  nRet = 2 + (int)strlen(zInput)*2 + 1;
+  zRet = sqlite3_malloc(nRet);
+  if( zRet ){
+    int i;
+    char *z = zRet;
+    *(z++) = '"';
+    for(i=0; zInput[i]; i++){
+      if( zInput[i]=='"' ) *(z++) = '"';
+      *(z++) = zInput[i];
+    }
+    *(z++) = '"';
+    *(z++) = '\0';
+  }
+  return zRet;
+}
+
+/*
+** Return a list of comma separated SQL expressions and a FROM clause that 
+** could be used in a SELECT statement such as the following:
+**
+**     SELECT <list of expressions> FROM %_content AS x ...
+**
+** to return the docid, followed by each column of text data in order
+** from left to write. If parameter zFunc is not NULL, then instead of
+** being returned directly each column of text data is passed to an SQL
+** function named zFunc first. For example, if zFunc is "unzip" and the
+** table has the three user-defined columns "a", "b", and "c", the following
+** string is returned:
+**
+**     "docid, unzip(x.'a'), unzip(x.'b'), unzip(x.'c') FROM %_content AS x"
+**
+** The pointer returned points to a buffer allocated by sqlite3_malloc(). It
+** is the responsibility of the caller to eventually free it.
+**
+** If *pRc is not SQLITE_OK when this function is called, it is a no-op (and
+** a NULL pointer is returned). Otherwise, if an OOM error is encountered
+** by this function, NULL is returned and *pRc is set to SQLITE_NOMEM. If
+** no error occurs, *pRc is left unmodified.
+*/
+static char *fts3ReadExprList(Fts3Table *p, const char *zFunc, int *pRc){
+  char *zRet = 0;
+  char *zFree = 0;
+  char *zFunction;
+  int i;
+
+  if( p->zContentTbl==0 ){
+    if( !zFunc ){
+      zFunction = "";
+    }else{
+      zFree = zFunction = fts3QuoteId(zFunc);
+    }
+    fts3Appendf(pRc, &zRet, "docid");
+    for(i=0; i<p->nColumn; i++){
+      fts3Appendf(pRc, &zRet, ",%s(x.'c%d%q')", zFunction, i, p->azColumn[i]);
+    }
+    if( p->zLanguageid ){
+      fts3Appendf(pRc, &zRet, ", x.%Q", "langid");
+    }
+    sqlite3_free(zFree);
+  }else{
+    fts3Appendf(pRc, &zRet, "rowid");
+    for(i=0; i<p->nColumn; i++){
+      fts3Appendf(pRc, &zRet, ", x.'%q'", p->azColumn[i]);
+    }
+    if( p->zLanguageid ){
+      fts3Appendf(pRc, &zRet, ", x.%Q", p->zLanguageid);
+    }
+  }
+  fts3Appendf(pRc, &zRet, " FROM '%q'.'%q%s' AS x", 
+      p->zDb,
+      (p->zContentTbl ? p->zContentTbl : p->zName),
+      (p->zContentTbl ? "" : "_content")
+  );
+  return zRet;
+}
+
+/*
+** Return a list of N comma separated question marks, where N is the number
+** of columns in the %_content table (one for the docid plus one for each
+** user-defined text column).
+**
+** If argument zFunc is not NULL, then all but the first question mark
+** is preceded by zFunc and an open bracket, and followed by a closed
+** bracket. For example, if zFunc is "zip" and the FTS3 table has three 
+** user-defined text columns, the following string is returned:
+**
+**     "?, zip(?), zip(?), zip(?)"
+**
+** The pointer returned points to a buffer allocated by sqlite3_malloc(). It
+** is the responsibility of the caller to eventually free it.
+**
+** If *pRc is not SQLITE_OK when this function is called, it is a no-op (and
+** a NULL pointer is returned). Otherwise, if an OOM error is encountered
+** by this function, NULL is returned and *pRc is set to SQLITE_NOMEM. If
+** no error occurs, *pRc is left unmodified.
+*/
+static char *fts3WriteExprList(Fts3Table *p, const char *zFunc, int *pRc){
+  char *zRet = 0;
+  char *zFree = 0;
+  char *zFunction;
+  int i;
+
+  if( !zFunc ){
+    zFunction = "";
+  }else{
+    zFree = zFunction = fts3QuoteId(zFunc);
+  }
+  fts3Appendf(pRc, &zRet, "?");
+  for(i=0; i<p->nColumn; i++){
+    fts3Appendf(pRc, &zRet, ",%s(?)", zFunction);
+  }
+  if( p->zLanguageid ){
+    fts3Appendf(pRc, &zRet, ", ?");
+  }
+  sqlite3_free(zFree);
+  return zRet;
+}
+
+/*
+** This function interprets the string at (*pp) as a non-negative integer
+** value. It reads the integer and sets *pnOut to the value read, then 
+** sets *pp to point to the byte immediately following the last byte of
+** the integer value.
+**
+** Only decimal digits ('0'..'9') may be part of an integer value. 
+**
+** If *pp does not being with a decimal digit SQLITE_ERROR is returned and
+** the output value undefined. Otherwise SQLITE_OK is returned.
+**
+** This function is used when parsing the "prefix=" FTS4 parameter.
+*/
+static int fts3GobbleInt(const char **pp, int *pnOut){
+  const int MAX_NPREFIX = 10000000;
+  const char *p;                  /* Iterator pointer */
+  int nInt = 0;                   /* Output value */
+
+  for(p=*pp; p[0]>='0' && p[0]<='9'; p++){
+    nInt = nInt * 10 + (p[0] - '0');
+    if( nInt>MAX_NPREFIX ){
+      nInt = 0;
+      break;
+    }
+  }
+  if( p==*pp ) return SQLITE_ERROR;
+  *pnOut = nInt;
+  *pp = p;
+  return SQLITE_OK;
+}
+
+/*
+** This function is called to allocate an array of Fts3Index structures
+** representing the indexes maintained by the current FTS table. FTS tables
+** always maintain the main "terms" index, but may also maintain one or
+** more "prefix" indexes, depending on the value of the "prefix=" parameter
+** (if any) specified as part of the CREATE VIRTUAL TABLE statement.
+**
+** Argument zParam is passed the value of the "prefix=" option if one was
+** specified, or NULL otherwise.
+**
+** If no error occurs, SQLITE_OK is returned and *apIndex set to point to
+** the allocated array. *pnIndex is set to the number of elements in the
+** array. If an error does occur, an SQLite error code is returned.
+**
+** Regardless of whether or not an error is returned, it is the responsibility
+** of the caller to call sqlite3_free() on the output array to free it.
+*/
+static int fts3PrefixParameter(
+  const char *zParam,             /* ABC in prefix=ABC parameter to parse */
+  int *pnIndex,                   /* OUT: size of *apIndex[] array */
+  struct Fts3Index **apIndex      /* OUT: Array of indexes for this table */
+){
+  struct Fts3Index *aIndex;       /* Allocated array */
+  int nIndex = 1;                 /* Number of entries in array */
+
+  if( zParam && zParam[0] ){
+    const char *p;
+    nIndex++;
+    for(p=zParam; *p; p++){
+      if( *p==',' ) nIndex++;
+    }
+  }
+
+  aIndex = sqlite3_malloc(sizeof(struct Fts3Index) * nIndex);
+  *apIndex = aIndex;
+  if( !aIndex ){
+    return SQLITE_NOMEM;
+  }
+
+  memset(aIndex, 0, sizeof(struct Fts3Index) * nIndex);
+  if( zParam ){
+    const char *p = zParam;
+    int i;
+    for(i=1; i<nIndex; i++){
+      int nPrefix = 0;
+      if( fts3GobbleInt(&p, &nPrefix) ) return SQLITE_ERROR;
+      assert( nPrefix>=0 );
+      if( nPrefix==0 ){
+        nIndex--;
+        i--;
+      }else{
+        aIndex[i].nPrefix = nPrefix;
+      }
+      p++;
+    }
+  }
+
+  *pnIndex = nIndex;
+  return SQLITE_OK;
+}
+
+/*
+** This function is called when initializing an FTS4 table that uses the
+** content=xxx option. It determines the number of and names of the columns
+** of the new FTS4 table.
+**
+** The third argument passed to this function is the value passed to the
+** config=xxx option (i.e. "xxx"). This function queries the database for
+** a table of that name. If found, the output variables are populated
+** as follows:
+**
+**   *pnCol:   Set to the number of columns table xxx has,
+**
+**   *pnStr:   Set to the total amount of space required to store a copy
+**             of each columns name, including the nul-terminator.
+**
+**   *pazCol:  Set to point to an array of *pnCol strings. Each string is
+**             the name of the corresponding column in table xxx. The array
+**             and its contents are allocated using a single allocation. It
+**             is the responsibility of the caller to free this allocation
+**             by eventually passing the *pazCol value to sqlite3_free().
+**
+** If the table cannot be found, an error code is returned and the output
+** variables are undefined. Or, if an OOM is encountered, SQLITE_NOMEM is
+** returned (and the output variables are undefined).
+*/
+static int fts3ContentColumns(
+  sqlite3 *db,                    /* Database handle */
+  const char *zDb,                /* Name of db (i.e. "main", "temp" etc.) */
+  const char *zTbl,               /* Name of content table */
+  const char ***pazCol,           /* OUT: Malloc'd array of column names */
+  int *pnCol,                     /* OUT: Size of array *pazCol */
+  int *pnStr,                     /* OUT: Bytes of string content */
+  char **pzErr                    /* OUT: error message */
+){
+  int rc = SQLITE_OK;             /* Return code */
+  char *zSql;                     /* "SELECT *" statement on zTbl */  
+  sqlite3_stmt *pStmt = 0;        /* Compiled version of zSql */
+
+  zSql = sqlite3_mprintf("SELECT * FROM %Q.%Q", zDb, zTbl);
+  if( !zSql ){
+    rc = SQLITE_NOMEM;
+  }else{
+    rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
+    if( rc!=SQLITE_OK ){
+      sqlite3Fts3ErrMsg(pzErr, "%s", sqlite3_errmsg(db));
+    }
+  }
+  sqlite3_free(zSql);
+
+  if( rc==SQLITE_OK ){
+    const char **azCol;           /* Output array */
+    int nStr = 0;                 /* Size of all column names (incl. 0x00) */
+    int nCol;                     /* Number of table columns */
+    int i;                        /* Used to iterate through columns */
+
+    /* Loop through the returned columns. Set nStr to the number of bytes of
+    ** space required to store a copy of each column name, including the
+    ** nul-terminator byte.  */
+    nCol = sqlite3_column_count(pStmt);
+    for(i=0; i<nCol; i++){
+      const char *zCol = sqlite3_column_name(pStmt, i);
+      nStr += (int)strlen(zCol) + 1;
+    }
+
+    /* Allocate and populate the array to return. */
+    azCol = (const char **)sqlite3_malloc(sizeof(char *) * nCol + nStr);
+    if( azCol==0 ){
+      rc = SQLITE_NOMEM;
+    }else{
+      char *p = (char *)&azCol[nCol];
+      for(i=0; i<nCol; i++){
+        const char *zCol = sqlite3_column_name(pStmt, i);
+        int n = (int)strlen(zCol)+1;
+        memcpy(p, zCol, n);
+        azCol[i] = p;
+        p += n;
+      }
+    }
+    sqlite3_finalize(pStmt);
+
+    /* Set the output variables. */
+    *pnCol = nCol;
+    *pnStr = nStr;
+    *pazCol = azCol;
+  }
+
+  return rc;
+}
+
+/*
+** This function is the implementation of both the xConnect and xCreate
+** methods of the FTS3 virtual table.
+**
+** The argv[] array contains the following:
+**
+**   argv[0]   -> module name  ("fts3" or "fts4")
+**   argv[1]   -> database name
+**   argv[2]   -> table name
+**   argv[...] -> "column name" and other module argument fields.
+*/
+static int fts3InitVtab(
+  int isCreate,                   /* True for xCreate, false for xConnect */
+  sqlite3 *db,                    /* The SQLite database connection */
+  void *pAux,                     /* Hash table containing tokenizers */
+  int argc,                       /* Number of elements in argv array */
+  const char * const *argv,       /* xCreate/xConnect argument array */
+  sqlite3_vtab **ppVTab,          /* Write the resulting vtab structure here */
+  char **pzErr                    /* Write any error message here */
+){
+  Fts3Hash *pHash = (Fts3Hash *)pAux;
+  Fts3Table *p = 0;               /* Pointer to allocated vtab */
+  int rc = SQLITE_OK;             /* Return code */
+  int i;                          /* Iterator variable */
+  int nByte;                      /* Size of allocation used for *p */
+  int iCol;                       /* Column index */
+  int nString = 0;                /* Bytes required to hold all column names */
+  int nCol = 0;                   /* Number of columns in the FTS table */
+  char *zCsr;                     /* Space for holding column names */
+  int nDb;                        /* Bytes required to hold database name */
+  int nName;                      /* Bytes required to hold table name */
+  int isFts4 = (argv[0][3]=='4'); /* True for FTS4, false for FTS3 */
+  const char **aCol;              /* Array of column names */
+  sqlite3_tokenizer *pTokenizer = 0;        /* Tokenizer for this table */
+
+  int nIndex = 0;                 /* Size of aIndex[] array */
+  struct Fts3Index *aIndex = 0;   /* Array of indexes for this table */
+
+  /* The results of parsing supported FTS4 key=value options: */
+  int bNoDocsize = 0;             /* True to omit %_docsize table */
+  int bDescIdx = 0;               /* True to store descending indexes */
+  char *zPrefix = 0;              /* Prefix parameter value (or NULL) */
+  char *zCompress = 0;            /* compress=? parameter (or NULL) */
+  char *zUncompress = 0;          /* uncompress=? parameter (or NULL) */
+  char *zContent = 0;             /* content=? parameter (or NULL) */
+  char *zLanguageid = 0;          /* languageid=? parameter (or NULL) */
+  char **azNotindexed = 0;        /* The set of notindexed= columns */
+  int nNotindexed = 0;            /* Size of azNotindexed[] array */
+
+  assert( strlen(argv[0])==4 );
+  assert( (sqlite3_strnicmp(argv[0], "fts4", 4)==0 && isFts4)
+       || (sqlite3_strnicmp(argv[0], "fts3", 4)==0 && !isFts4)
+  );
+
+  nDb = (int)strlen(argv[1]) + 1;
+  nName = (int)strlen(argv[2]) + 1;
+
+  nByte = sizeof(const char *) * (argc-2);
+  aCol = (const char **)sqlite3_malloc(nByte);
+  if( aCol ){
+    memset((void*)aCol, 0, nByte);
+    azNotindexed = (char **)sqlite3_malloc(nByte);
+  }
+  if( azNotindexed ){
+    memset(azNotindexed, 0, nByte);
+  }
+  if( !aCol || !azNotindexed ){
+    rc = SQLITE_NOMEM;
+    goto fts3_init_out;
+  }
+
+  /* Loop through all of the arguments passed by the user to the FTS3/4
+  ** module (i.e. all the column names and special arguments). This loop
+  ** does the following:
+  **
+  **   + Figures out the number of columns the FTSX table will have, and
+  **     the number of bytes of space that must be allocated to store copies
+  **     of the column names.
+  **
+  **   + If there is a tokenizer specification included in the arguments,
+  **     initializes the tokenizer pTokenizer.
+  */
+  for(i=3; rc==SQLITE_OK && i<argc; i++){
+    char const *z = argv[i];
+    int nKey;
+    char *zVal;
+
+    /* Check if this is a tokenizer specification */
+    if( !pTokenizer 
+     && strlen(z)>8
+     && 0==sqlite3_strnicmp(z, "tokenize", 8) 
+     && 0==sqlite3Fts3IsIdChar(z[8])
+    ){
+      rc = sqlite3Fts3InitTokenizer(pHash, &z[9], &pTokenizer, pzErr);
+    }
+
+    /* Check if it is an FTS4 special argument. */
+    else if( isFts4 && fts3IsSpecialColumn(z, &nKey, &zVal) ){
+      struct Fts4Option {
+        const char *zOpt;
+        int nOpt;
+      } aFts4Opt[] = {
+        { "matchinfo",   9 },     /* 0 -> MATCHINFO */
+        { "prefix",      6 },     /* 1 -> PREFIX */
+        { "compress",    8 },     /* 2 -> COMPRESS */
+        { "uncompress", 10 },     /* 3 -> UNCOMPRESS */
+        { "order",       5 },     /* 4 -> ORDER */
+        { "content",     7 },     /* 5 -> CONTENT */
+        { "languageid", 10 },     /* 6 -> LANGUAGEID */
+        { "notindexed", 10 }      /* 7 -> NOTINDEXED */
+      };
+
+      int iOpt;
+      if( !zVal ){
+        rc = SQLITE_NOMEM;
+      }else{
+        for(iOpt=0; iOpt<SizeofArray(aFts4Opt); iOpt++){
+          struct Fts4Option *pOp = &aFts4Opt[iOpt];
+          if( nKey==pOp->nOpt && !sqlite3_strnicmp(z, pOp->zOpt, pOp->nOpt) ){
+            break;
+          }
+        }
+        if( iOpt==SizeofArray(aFts4Opt) ){
+          sqlite3Fts3ErrMsg(pzErr, "unrecognized parameter: %s", z);
+          rc = SQLITE_ERROR;
+        }else{
+          switch( iOpt ){
+            case 0:               /* MATCHINFO */
+              if( strlen(zVal)!=4 || sqlite3_strnicmp(zVal, "fts3", 4) ){
+                sqlite3Fts3ErrMsg(pzErr, "unrecognized matchinfo: %s", zVal);
+                rc = SQLITE_ERROR;
+              }
+              bNoDocsize = 1;
+              break;
+
+            case 1:               /* PREFIX */
+              sqlite3_free(zPrefix);
+              zPrefix = zVal;
+              zVal = 0;
+              break;
+
+            case 2:               /* COMPRESS */
+              sqlite3_free(zCompress);
+              zCompress = zVal;
+              zVal = 0;
+              break;
+
+            case 3:               /* UNCOMPRESS */
+              sqlite3_free(zUncompress);
+              zUncompress = zVal;
+              zVal = 0;
+              break;
+
+            case 4:               /* ORDER */
+              if( (strlen(zVal)!=3 || sqlite3_strnicmp(zVal, "asc", 3)) 
+               && (strlen(zVal)!=4 || sqlite3_strnicmp(zVal, "desc", 4)) 
+              ){
+                sqlite3Fts3ErrMsg(pzErr, "unrecognized order: %s", zVal);
+                rc = SQLITE_ERROR;
+              }
+              bDescIdx = (zVal[0]=='d' || zVal[0]=='D');
+              break;
+
+            case 5:              /* CONTENT */
+              sqlite3_free(zContent);
+              zContent = zVal;
+              zVal = 0;
+              break;
+
+            case 6:              /* LANGUAGEID */
+              assert( iOpt==6 );
+              sqlite3_free(zLanguageid);
+              zLanguageid = zVal;
+              zVal = 0;
+              break;
+
+            case 7:              /* NOTINDEXED */
+              azNotindexed[nNotindexed++] = zVal;
+              zVal = 0;
+              break;
+          }
+        }
+        sqlite3_free(zVal);
+      }
+    }
+
+    /* Otherwise, the argument is a column name. */
+    else {
+      nString += (int)(strlen(z) + 1);
+      aCol[nCol++] = z;
+    }
+  }
+
+  /* If a content=xxx option was specified, the following:
+  **
+  **   1. Ignore any compress= and uncompress= options.
+  **
+  **   2. If no column names were specified as part of the CREATE VIRTUAL
+  **      TABLE statement, use all columns from the content table.
+  */
+  if( rc==SQLITE_OK && zContent ){
+    sqlite3_free(zCompress); 
+    sqlite3_free(zUncompress); 
+    zCompress = 0;
+    zUncompress = 0;
+    if( nCol==0 ){
+      sqlite3_free((void*)aCol); 
+      aCol = 0;
+      rc = fts3ContentColumns(db, argv[1], zContent,&aCol,&nCol,&nString,pzErr);
+
+      /* If a languageid= option was specified, remove the language id
+      ** column from the aCol[] array. */ 
+      if( rc==SQLITE_OK && zLanguageid ){
+        int j;
+        for(j=0; j<nCol; j++){
+          if( sqlite3_stricmp(zLanguageid, aCol[j])==0 ){
+            int k;
+            for(k=j; k<nCol; k++) aCol[k] = aCol[k+1];
+            nCol--;
+            break;
+          }
+        }
+      }
+    }
+  }
+  if( rc!=SQLITE_OK ) goto fts3_init_out;
+
+  if( nCol==0 ){
+    assert( nString==0 );
+    aCol[0] = "content";
+    nString = 8;
+    nCol = 1;
+  }
+
+  if( pTokenizer==0 ){
+    rc = sqlite3Fts3InitTokenizer(pHash, "simple", &pTokenizer, pzErr);
+    if( rc!=SQLITE_OK ) goto fts3_init_out;
+  }
+  assert( pTokenizer );
+
+  rc = fts3PrefixParameter(zPrefix, &nIndex, &aIndex);
+  if( rc==SQLITE_ERROR ){
+    assert( zPrefix );
+    sqlite3Fts3ErrMsg(pzErr, "error parsing prefix parameter: %s", zPrefix);
+  }
+  if( rc!=SQLITE_OK ) goto fts3_init_out;
+
+  /* Allocate and populate the Fts3Table structure. */
+  nByte = sizeof(Fts3Table) +                  /* Fts3Table */
+          nCol * sizeof(char *) +              /* azColumn */
+          nIndex * sizeof(struct Fts3Index) +  /* aIndex */
+          nCol * sizeof(u8) +                  /* abNotindexed */
+          nName +                              /* zName */
+          nDb +                                /* zDb */
+          nString;                             /* Space for azColumn strings */
+  p = (Fts3Table*)sqlite3_malloc(nByte);
+  if( p==0 ){
+    rc = SQLITE_NOMEM;
+    goto fts3_init_out;
+  }
+  memset(p, 0, nByte);
+  p->db = db;
+  p->nColumn = nCol;
+  p->nPendingData = 0;
+  p->azColumn = (char **)&p[1];
+  p->pTokenizer = pTokenizer;
+  p->nMaxPendingData = FTS3_MAX_PENDING_DATA;
+  p->bHasDocsize = (isFts4 && bNoDocsize==0);
+  p->bHasStat = isFts4;
+  p->bFts4 = isFts4;
+  p->bDescIdx = bDescIdx;
+  p->nAutoincrmerge = 0xff;   /* 0xff means setting unknown */
+  p->zContentTbl = zContent;
+  p->zLanguageid = zLanguageid;
+  zContent = 0;
+  zLanguageid = 0;
+  TESTONLY( p->inTransaction = -1 );
+  TESTONLY( p->mxSavepoint = -1 );
+
+  p->aIndex = (struct Fts3Index *)&p->azColumn[nCol];
+  memcpy(p->aIndex, aIndex, sizeof(struct Fts3Index) * nIndex);
+  p->nIndex = nIndex;
+  for(i=0; i<nIndex; i++){
+    fts3HashInit(&p->aIndex[i].hPending, FTS3_HASH_STRING, 1);
+  }
+  p->abNotindexed = (u8 *)&p->aIndex[nIndex];
+
+  /* Fill in the zName and zDb fields of the vtab structure. */
+  zCsr = (char *)&p->abNotindexed[nCol];
+  p->zName = zCsr;
+  memcpy(zCsr, argv[2], nName);
+  zCsr += nName;
+  p->zDb = zCsr;
+  memcpy(zCsr, argv[1], nDb);
+  zCsr += nDb;
+
+  /* Fill in the azColumn array */
+  for(iCol=0; iCol<nCol; iCol++){
+    char *z; 
+    int n = 0;
+    z = (char *)sqlite3Fts3NextToken(aCol[iCol], &n);
+    memcpy(zCsr, z, n);
+    zCsr[n] = '\0';
+    sqlite3Fts3Dequote(zCsr);
+    p->azColumn[iCol] = zCsr;
+    zCsr += n+1;
+    assert( zCsr <= &((char *)p)[nByte] );
+  }
+
+  /* Fill in the abNotindexed array */
+  for(iCol=0; iCol<nCol; iCol++){
+    int n = (int)strlen(p->azColumn[iCol]);
+    for(i=0; i<nNotindexed; i++){
+      char *zNot = azNotindexed[i];
+      if( zNot && n==(int)strlen(zNot)
+       && 0==sqlite3_strnicmp(p->azColumn[iCol], zNot, n) 
+      ){
+        p->abNotindexed[iCol] = 1;
+        sqlite3_free(zNot);
+        azNotindexed[i] = 0;
+      }
+    }
+  }
+  for(i=0; i<nNotindexed; i++){
+    if( azNotindexed[i] ){
+      sqlite3Fts3ErrMsg(pzErr, "no such column: %s", azNotindexed[i]);
+      rc = SQLITE_ERROR;
+    }
+  }
+
+  if( rc==SQLITE_OK && (zCompress==0)!=(zUncompress==0) ){
+    char const *zMiss = (zCompress==0 ? "compress" : "uncompress");
+    rc = SQLITE_ERROR;
+    sqlite3Fts3ErrMsg(pzErr, "missing %s parameter in fts4 constructor", zMiss);
+  }
+  p->zReadExprlist = fts3ReadExprList(p, zUncompress, &rc);
+  p->zWriteExprlist = fts3WriteExprList(p, zCompress, &rc);
+  if( rc!=SQLITE_OK ) goto fts3_init_out;
+
+  /* If this is an xCreate call, create the underlying tables in the 
+  ** database. TODO: For xConnect(), it could verify that said tables exist.
+  */
+  if( isCreate ){
+    rc = fts3CreateTables(p);
+  }
+
+  /* Check to see if a legacy fts3 table has been "upgraded" by the
+  ** addition of a %_stat table so that it can use incremental merge.
+  */
+  if( !isFts4 && !isCreate ){
+    p->bHasStat = 2;
+  }
+
+  /* Figure out the page-size for the database. This is required in order to
+  ** estimate the cost of loading large doclists from the database.  */
+  fts3DatabasePageSize(&rc, p);
+  p->nNodeSize = p->nPgsz-35;
+
+  /* Declare the table schema to SQLite. */
+  fts3DeclareVtab(&rc, p);
+
+fts3_init_out:
+  sqlite3_free(zPrefix);
+  sqlite3_free(aIndex);
+  sqlite3_free(zCompress);
+  sqlite3_free(zUncompress);
+  sqlite3_free(zContent);
+  sqlite3_free(zLanguageid);
+  for(i=0; i<nNotindexed; i++) sqlite3_free(azNotindexed[i]);
+  sqlite3_free((void *)aCol);
+  sqlite3_free((void *)azNotindexed);
+  if( rc!=SQLITE_OK ){
+    if( p ){
+      fts3DisconnectMethod((sqlite3_vtab *)p);
+    }else if( pTokenizer ){
+      pTokenizer->pModule->xDestroy(pTokenizer);
+    }
+  }else{
+    assert( p->pSegments==0 );
+    *ppVTab = &p->base;
+  }
+  return rc;
+}
+
+/*
+** The xConnect() and xCreate() methods for the virtual table. All the
+** work is done in function fts3InitVtab().
+*/
+static int fts3ConnectMethod(
+  sqlite3 *db,                    /* Database connection */
+  void *pAux,                     /* Pointer to tokenizer hash table */
+  int argc,                       /* Number of elements in argv array */
+  const char * const *argv,       /* xCreate/xConnect argument array */
+  sqlite3_vtab **ppVtab,          /* OUT: New sqlite3_vtab object */
+  char **pzErr                    /* OUT: sqlite3_malloc'd error message */
+){
+  return fts3InitVtab(0, db, pAux, argc, argv, ppVtab, pzErr);
+}
+static int fts3CreateMethod(
+  sqlite3 *db,                    /* Database connection */
+  void *pAux,                     /* Pointer to tokenizer hash table */
+  int argc,                       /* Number of elements in argv array */
+  const char * const *argv,       /* xCreate/xConnect argument array */
+  sqlite3_vtab **ppVtab,          /* OUT: New sqlite3_vtab object */
+  char **pzErr                    /* OUT: sqlite3_malloc'd error message */
+){
+  return fts3InitVtab(1, db, pAux, argc, argv, ppVtab, pzErr);
+}
+
+/*
+** Set the pIdxInfo->estimatedRows variable to nRow. Unless this
+** extension is currently being used by a version of SQLite too old to
+** support estimatedRows. In that case this function is a no-op.
+*/
+static void fts3SetEstimatedRows(sqlite3_index_info *pIdxInfo, i64 nRow){
+#if SQLITE_VERSION_NUMBER>=3008002
+  if( sqlite3_libversion_number()>=3008002 ){
+    pIdxInfo->estimatedRows = nRow;
+  }
+#endif
+}
+
+/*
+** Set the SQLITE_INDEX_SCAN_UNIQUE flag in pIdxInfo->flags. Unless this
+** extension is currently being used by a version of SQLite too old to
+** support index-info flags. In that case this function is a no-op.
+*/
+static void fts3SetUniqueFlag(sqlite3_index_info *pIdxInfo){
+#if SQLITE_VERSION_NUMBER>=3008012
+  if( sqlite3_libversion_number()>=3008012 ){
+    pIdxInfo->idxFlags |= SQLITE_INDEX_SCAN_UNIQUE;
+  }
+#endif
+}
+
+/* 
+** Implementation of the xBestIndex method for FTS3 tables. There
+** are three possible strategies, in order of preference:
+**
+**   1. Direct lookup by rowid or docid. 
+**   2. Full-text search using a MATCH operator on a non-docid column.
+**   3. Linear scan of %_content table.
+*/
+static int fts3BestIndexMethod(sqlite3_vtab *pVTab, sqlite3_index_info *pInfo){
+  Fts3Table *p = (Fts3Table *)pVTab;
+  int i;                          /* Iterator variable */
+  int iCons = -1;                 /* Index of constraint to use */
+
+  int iLangidCons = -1;           /* Index of langid=x constraint, if present */
+  int iDocidGe = -1;              /* Index of docid>=x constraint, if present */
+  int iDocidLe = -1;              /* Index of docid<=x constraint, if present */
+  int iIdx;
+
+  /* By default use a full table scan. This is an expensive option,
+  ** so search through the constraints to see if a more efficient 
+  ** strategy is possible.
+  */
+  pInfo->idxNum = FTS3_FULLSCAN_SEARCH;
+  pInfo->estimatedCost = 5000000;
+  for(i=0; i<pInfo->nConstraint; i++){
+    int bDocid;                 /* True if this constraint is on docid */
+    struct sqlite3_index_constraint *pCons = &pInfo->aConstraint[i];
+    if( pCons->usable==0 ){
+      if( pCons->op==SQLITE_INDEX_CONSTRAINT_MATCH ){
+        /* There exists an unusable MATCH constraint. This means that if
+        ** the planner does elect to use the results of this call as part
+        ** of the overall query plan the user will see an "unable to use
+        ** function MATCH in the requested context" error. To discourage
+        ** this, return a very high cost here.  */
+        pInfo->idxNum = FTS3_FULLSCAN_SEARCH;
+        pInfo->estimatedCost = 1e50;
+        fts3SetEstimatedRows(pInfo, ((sqlite3_int64)1) << 50);
+        return SQLITE_OK;
+      }
+      continue;
+    }
+
+    bDocid = (pCons->iColumn<0 || pCons->iColumn==p->nColumn+1);
+
+    /* A direct lookup on the rowid or docid column. Assign a cost of 1.0. */
+    if( iCons<0 && pCons->op==SQLITE_INDEX_CONSTRAINT_EQ && bDocid ){
+      pInfo->idxNum = FTS3_DOCID_SEARCH;
+      pInfo->estimatedCost = 1.0;
+      iCons = i;
+    }
+
+    /* A MATCH constraint. Use a full-text search.
+    **
+    ** If there is more than one MATCH constraint available, use the first
+    ** one encountered. If there is both a MATCH constraint and a direct
+    ** rowid/docid lookup, prefer the MATCH strategy. This is done even 
+    ** though the rowid/docid lookup is faster than a MATCH query, selecting
+    ** it would lead to an "unable to use function MATCH in the requested 
+    ** context" error.
+    */
+    if( pCons->op==SQLITE_INDEX_CONSTRAINT_MATCH 
+     && pCons->iColumn>=0 && pCons->iColumn<=p->nColumn
+    ){
+      pInfo->idxNum = FTS3_FULLTEXT_SEARCH + pCons->iColumn;
+      pInfo->estimatedCost = 2.0;
+      iCons = i;
+    }
+
+    /* Equality constraint on the langid column */
+    if( pCons->op==SQLITE_INDEX_CONSTRAINT_EQ 
+     && pCons->iColumn==p->nColumn + 2
+    ){
+      iLangidCons = i;
+    }
+
+    if( bDocid ){
+      switch( pCons->op ){
+        case SQLITE_INDEX_CONSTRAINT_GE:
+        case SQLITE_INDEX_CONSTRAINT_GT:
+          iDocidGe = i;
+          break;
+
+        case SQLITE_INDEX_CONSTRAINT_LE:
+        case SQLITE_INDEX_CONSTRAINT_LT:
+          iDocidLe = i;
+          break;
+      }
+    }
+  }
+
+  /* If using a docid=? or rowid=? strategy, set the UNIQUE flag. */
+  if( pInfo->idxNum==FTS3_DOCID_SEARCH ) fts3SetUniqueFlag(pInfo);
+
+  iIdx = 1;
+  if( iCons>=0 ){
+    pInfo->aConstraintUsage[iCons].argvIndex = iIdx++;
+    pInfo->aConstraintUsage[iCons].omit = 1;
+  } 
+  if( iLangidCons>=0 ){
+    pInfo->idxNum |= FTS3_HAVE_LANGID;
+    pInfo->aConstraintUsage[iLangidCons].argvIndex = iIdx++;
+  } 
+  if( iDocidGe>=0 ){
+    pInfo->idxNum |= FTS3_HAVE_DOCID_GE;
+    pInfo->aConstraintUsage[iDocidGe].argvIndex = iIdx++;
+  } 
+  if( iDocidLe>=0 ){
+    pInfo->idxNum |= FTS3_HAVE_DOCID_LE;
+    pInfo->aConstraintUsage[iDocidLe].argvIndex = iIdx++;
+  } 
+
+  /* Regardless of the strategy selected, FTS can deliver rows in rowid (or
+  ** docid) order. Both ascending and descending are possible. 
+  */
+  if( pInfo->nOrderBy==1 ){
+    struct sqlite3_index_orderby *pOrder = &pInfo->aOrderBy[0];
+    if( pOrder->iColumn<0 || pOrder->iColumn==p->nColumn+1 ){
+      if( pOrder->desc ){
+        pInfo->idxStr = "DESC";
+      }else{
+        pInfo->idxStr = "ASC";
+      }
+      pInfo->orderByConsumed = 1;
+    }
+  }
+
+  assert( p->pSegments==0 );
+  return SQLITE_OK;
+}
+
+/*
+** Implementation of xOpen method.
+*/
+static int fts3OpenMethod(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCsr){
+  sqlite3_vtab_cursor *pCsr;               /* Allocated cursor */
+
+  UNUSED_PARAMETER(pVTab);
+
+  /* Allocate a buffer large enough for an Fts3Cursor structure. If the
+  ** allocation succeeds, zero it and return SQLITE_OK. Otherwise, 
+  ** if the allocation fails, return SQLITE_NOMEM.
+  */
+  *ppCsr = pCsr = (sqlite3_vtab_cursor *)sqlite3_malloc(sizeof(Fts3Cursor));
+  if( !pCsr ){
+    return SQLITE_NOMEM;
+  }
+  memset(pCsr, 0, sizeof(Fts3Cursor));
+  return SQLITE_OK;
+}
+
+/*
+** Close the cursor.  For additional information see the documentation
+** on the xClose method of the virtual table interface.
+*/
+static int fts3CloseMethod(sqlite3_vtab_cursor *pCursor){
+  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;
+  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
+  sqlite3_finalize(pCsr->pStmt);
+  sqlite3Fts3ExprFree(pCsr->pExpr);
+  sqlite3Fts3FreeDeferredTokens(pCsr);
+  sqlite3_free(pCsr->aDoclist);
+  sqlite3Fts3MIBufferFree(pCsr->pMIBuffer);
+  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
+  sqlite3_free(pCsr);
+  return SQLITE_OK;
+}
+
+/*
+** If pCsr->pStmt has not been prepared (i.e. if pCsr->pStmt==0), then
+** compose and prepare an SQL statement of the form:
+**
+**    "SELECT <columns> FROM %_content WHERE rowid = ?"
+**
+** (or the equivalent for a content=xxx table) and set pCsr->pStmt to
+** it. If an error occurs, return an SQLite error code.
+**
+** Otherwise, set *ppStmt to point to pCsr->pStmt and return SQLITE_OK.
+*/
+static int fts3CursorSeekStmt(Fts3Cursor *pCsr, sqlite3_stmt **ppStmt){
+  int rc = SQLITE_OK;
+  if( pCsr->pStmt==0 ){
+    Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
+    char *zSql;
+    zSql = sqlite3_mprintf("SELECT %s WHERE rowid = ?", p->zReadExprlist);
+    if( !zSql ) return SQLITE_NOMEM;
+    rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
+    sqlite3_free(zSql);
+  }
+  *ppStmt = pCsr->pStmt;
+  return rc;
+}
+
+/*
+** Position the pCsr->pStmt statement so that it is on the row
+** of the %_content table that contains the last match.  Return
+** SQLITE_OK on success.  
+*/
+static int fts3CursorSeek(sqlite3_context *pContext, Fts3Cursor *pCsr){
+  int rc = SQLITE_OK;
+  if( pCsr->isRequireSeek ){
+    sqlite3_stmt *pStmt = 0;
+
+    rc = fts3CursorSeekStmt(pCsr, &pStmt);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_int64(pCsr->pStmt, 1, pCsr->iPrevId);
+      pCsr->isRequireSeek = 0;
+      if( SQLITE_ROW==sqlite3_step(pCsr->pStmt) ){
+        return SQLITE_OK;
+      }else{
+        rc = sqlite3_reset(pCsr->pStmt);
+        if( rc==SQLITE_OK && ((Fts3Table *)pCsr->base.pVtab)->zContentTbl==0 ){
+          /* If no row was found and no error has occurred, then the %_content
+          ** table is missing a row that is present in the full-text index.
+          ** The data structures are corrupt.  */
+          rc = FTS_CORRUPT_VTAB;
+          pCsr->isEof = 1;
+        }
+      }
+    }
+  }
+
+  if( rc!=SQLITE_OK && pContext ){
+    sqlite3_result_error_code(pContext, rc);
+  }
+  return rc;
+}
+
+/*
+** This function is used to process a single interior node when searching
+** a b-tree for a term or term prefix. The node data is passed to this 
+** function via the zNode/nNode parameters. The term to search for is
+** passed in zTerm/nTerm.
+**
+** If piFirst is not NULL, then this function sets *piFirst to the blockid
+** of the child node that heads the sub-tree that may contain the term.
+**
+** If piLast is not NULL, then *piLast is set to the right-most child node
+** that heads a sub-tree that may contain a term for which zTerm/nTerm is
+** a prefix.
+**
+** If an OOM error occurs, SQLITE_NOMEM is returned. Otherwise, SQLITE_OK.
+*/
+static int fts3ScanInteriorNode(
+  const char *zTerm,              /* Term to select leaves for */
+  int nTerm,                      /* Size of term zTerm in bytes */
+  const char *zNode,              /* Buffer containing segment interior node */
+  int nNode,                      /* Size of buffer at zNode */
+  sqlite3_int64 *piFirst,         /* OUT: Selected child node */
+  sqlite3_int64 *piLast           /* OUT: Selected child node */
+){
+  int rc = SQLITE_OK;             /* Return code */
+  const char *zCsr = zNode;       /* Cursor to iterate through node */
+  const char *zEnd = &zCsr[nNode];/* End of interior node buffer */
+  char *zBuffer = 0;              /* Buffer to load terms into */
+  int nAlloc = 0;                 /* Size of allocated buffer */
+  int isFirstTerm = 1;            /* True when processing first term on page */
+  sqlite3_int64 iChild;           /* Block id of child node to descend to */
+
+  /* Skip over the 'height' varint that occurs at the start of every 
+  ** interior node. Then load the blockid of the left-child of the b-tree
+  ** node into variable iChild.  
+  **
+  ** Even if the data structure on disk is corrupted, this (reading two
+  ** varints from the buffer) does not risk an overread. If zNode is a
+  ** root node, then the buffer comes from a SELECT statement. SQLite does
+  ** not make this guarantee explicitly, but in practice there are always
+  ** either more than 20 bytes of allocated space following the nNode bytes of
+  ** contents, or two zero bytes. Or, if the node is read from the %_segments
+  ** table, then there are always 20 bytes of zeroed padding following the
+  ** nNode bytes of content (see sqlite3Fts3ReadBlock() for details).
+  */
+  zCsr += sqlite3Fts3GetVarint(zCsr, &iChild);
+  zCsr += sqlite3Fts3GetVarint(zCsr, &iChild);
+  if( zCsr>zEnd ){
+    return FTS_CORRUPT_VTAB;
+  }
+  
+  while( zCsr<zEnd && (piFirst || piLast) ){
+    int cmp;                      /* memcmp() result */
+    int nSuffix;                  /* Size of term suffix */
+    int nPrefix = 0;              /* Size of term prefix */
+    int nBuffer;                  /* Total term size */
+  
+    /* Load the next term on the node into zBuffer. Use realloc() to expand
+    ** the size of zBuffer if required.  */
+    if( !isFirstTerm ){
+      zCsr += fts3GetVarint32(zCsr, &nPrefix);
+    }
+    isFirstTerm = 0;
+    zCsr += fts3GetVarint32(zCsr, &nSuffix);
+    
+    if( nPrefix<0 || nSuffix<0 || &zCsr[nSuffix]>zEnd ){
+      rc = FTS_CORRUPT_VTAB;
+      goto finish_scan;
+    }
+    if( nPrefix+nSuffix>nAlloc ){
+      char *zNew;
+      nAlloc = (nPrefix+nSuffix) * 2;
+      zNew = (char *)sqlite3_realloc(zBuffer, nAlloc);
+      if( !zNew ){
+        rc = SQLITE_NOMEM;
+        goto finish_scan;
+      }
+      zBuffer = zNew;
+    }
+    assert( zBuffer );
+    memcpy(&zBuffer[nPrefix], zCsr, nSuffix);
+    nBuffer = nPrefix + nSuffix;
+    zCsr += nSuffix;
+
+    /* Compare the term we are searching for with the term just loaded from
+    ** the interior node. If the specified term is greater than or equal
+    ** to the term from the interior node, then all terms on the sub-tree 
+    ** headed by node iChild are smaller than zTerm. No need to search 
+    ** iChild.
+    **
+    ** If the interior node term is larger than the specified term, then
+    ** the tree headed by iChild may contain the specified term.
+    */
+    cmp = memcmp(zTerm, zBuffer, (nBuffer>nTerm ? nTerm : nBuffer));
+    if( piFirst && (cmp<0 || (cmp==0 && nBuffer>nTerm)) ){
+      *piFirst = iChild;
+      piFirst = 0;
+    }
+
+    if( piLast && cmp<0 ){
+      *piLast = iChild;
+      piLast = 0;
+    }
+
+    iChild++;
+  };
+
+  if( piFirst ) *piFirst = iChild;
+  if( piLast ) *piLast = iChild;
+
+ finish_scan:
+  sqlite3_free(zBuffer);
+  return rc;
+}
+
+
+/*
+** The buffer pointed to by argument zNode (size nNode bytes) contains an
+** interior node of a b-tree segment. The zTerm buffer (size nTerm bytes)
+** contains a term. This function searches the sub-tree headed by the zNode
+** node for the range of leaf nodes that may contain the specified term
+** or terms for which the specified term is a prefix.
+**
+** If piLeaf is not NULL, then *piLeaf is set to the blockid of the 
+** left-most leaf node in the tree that may contain the specified term.
+** If piLeaf2 is not NULL, then *piLeaf2 is set to the blockid of the
+** right-most leaf node that may contain a term for which the specified
+** term is a prefix.
+**
+** It is possible that the range of returned leaf nodes does not contain 
+** the specified term or any terms for which it is a prefix. However, if the 
+** segment does contain any such terms, they are stored within the identified
+** range. Because this function only inspects interior segment nodes (and
+** never loads leaf nodes into memory), it is not possible to be sure.
+**
+** If an error occurs, an error code other than SQLITE_OK is returned.
+*/ 
+static int fts3SelectLeaf(
+  Fts3Table *p,                   /* Virtual table handle */
+  const char *zTerm,              /* Term to select leaves for */
+  int nTerm,                      /* Size of term zTerm in bytes */
+  const char *zNode,              /* Buffer containing segment interior node */
+  int nNode,                      /* Size of buffer at zNode */
+  sqlite3_int64 *piLeaf,          /* Selected leaf node */
+  sqlite3_int64 *piLeaf2          /* Selected leaf node */
+){
+  int rc = SQLITE_OK;             /* Return code */
+  int iHeight;                    /* Height of this node in tree */
+
+  assert( piLeaf || piLeaf2 );
+
+  fts3GetVarint32(zNode, &iHeight);
+  rc = fts3ScanInteriorNode(zTerm, nTerm, zNode, nNode, piLeaf, piLeaf2);
+  assert( !piLeaf2 || !piLeaf || rc!=SQLITE_OK || (*piLeaf<=*piLeaf2) );
+
+  if( rc==SQLITE_OK && iHeight>1 ){
+    char *zBlob = 0;              /* Blob read from %_segments table */
+    int nBlob = 0;                /* Size of zBlob in bytes */
+
+    if( piLeaf && piLeaf2 && (*piLeaf!=*piLeaf2) ){
+      rc = sqlite3Fts3ReadBlock(p, *piLeaf, &zBlob, &nBlob, 0);
+      if( rc==SQLITE_OK ){
+        rc = fts3SelectLeaf(p, zTerm, nTerm, zBlob, nBlob, piLeaf, 0);
+      }
+      sqlite3_free(zBlob);
+      piLeaf = 0;
+      zBlob = 0;
+    }
+
+    if( rc==SQLITE_OK ){
+      rc = sqlite3Fts3ReadBlock(p, piLeaf?*piLeaf:*piLeaf2, &zBlob, &nBlob, 0);
+    }
+    if( rc==SQLITE_OK ){
+      rc = fts3SelectLeaf(p, zTerm, nTerm, zBlob, nBlob, piLeaf, piLeaf2);
+    }
+    sqlite3_free(zBlob);
+  }
+
+  return rc;
+}
+
+/*
+** This function is used to create delta-encoded serialized lists of FTS3 
+** varints. Each call to this function appends a single varint to a list.
+*/
+static void fts3PutDeltaVarint(
+  char **pp,                      /* IN/OUT: Output pointer */
+  sqlite3_int64 *piPrev,          /* IN/OUT: Previous value written to list */
+  sqlite3_int64 iVal              /* Write this value to the list */
+){
+  assert( iVal-*piPrev > 0 || (*piPrev==0 && iVal==0) );
+  *pp += sqlite3Fts3PutVarint(*pp, iVal-*piPrev);
+  *piPrev = iVal;
+}
+
+/*
+** When this function is called, *ppPoslist is assumed to point to the 
+** start of a position-list. After it returns, *ppPoslist points to the
+** first byte after the position-list.
+**
+** A position list is list of positions (delta encoded) and columns for 
+** a single document record of a doclist.  So, in other words, this
+** routine advances *ppPoslist so that it points to the next docid in
+** the doclist, or to the first byte past the end of the doclist.
+**
+** If pp is not NULL, then the contents of the position list are copied
+** to *pp. *pp is set to point to the first byte past the last byte copied
+** before this function returns.
+*/
+static void fts3PoslistCopy(char **pp, char **ppPoslist){
+  char *pEnd = *ppPoslist;
+  char c = 0;
+
+  /* The end of a position list is marked by a zero encoded as an FTS3 
+  ** varint. A single POS_END (0) byte. Except, if the 0 byte is preceded by
+  ** a byte with the 0x80 bit set, then it is not a varint 0, but the tail
+  ** of some other, multi-byte, value.
+  **
+  ** The following while-loop moves pEnd to point to the first byte that is not 
+  ** immediately preceded by a byte with the 0x80 bit set. Then increments
+  ** pEnd once more so that it points to the byte immediately following the
+  ** last byte in the position-list.
+  */
+  while( *pEnd | c ){
+    c = *pEnd++ & 0x80;
+    testcase( c!=0 && (*pEnd)==0 );
+  }
+  pEnd++;  /* Advance past the POS_END terminator byte */
+
+  if( pp ){
+    int n = (int)(pEnd - *ppPoslist);
+    char *p = *pp;
+    memcpy(p, *ppPoslist, n);
+    p += n;
+    *pp = p;
+  }
+  *ppPoslist = pEnd;
+}
+
+/*
+** When this function is called, *ppPoslist is assumed to point to the 
+** start of a column-list. After it returns, *ppPoslist points to the
+** to the terminator (POS_COLUMN or POS_END) byte of the column-list.
+**
+** A column-list is list of delta-encoded positions for a single column
+** within a single document within a doclist.
+**
+** The column-list is terminated either by a POS_COLUMN varint (1) or
+** a POS_END varint (0).  This routine leaves *ppPoslist pointing to
+** the POS_COLUMN or POS_END that terminates the column-list.
+**
+** If pp is not NULL, then the contents of the column-list are copied
+** to *pp. *pp is set to point to the first byte past the last byte copied
+** before this function returns.  The POS_COLUMN or POS_END terminator
+** is not copied into *pp.
+*/
+static void fts3ColumnlistCopy(char **pp, char **ppPoslist){
+  char *pEnd = *ppPoslist;
+  char c = 0;
+
+  /* A column-list is terminated by either a 0x01 or 0x00 byte that is
+  ** not part of a multi-byte varint.
+  */
+  while( 0xFE & (*pEnd | c) ){
+    c = *pEnd++ & 0x80;
+    testcase( c!=0 && ((*pEnd)&0xfe)==0 );
+  }
+  if( pp ){
+    int n = (int)(pEnd - *ppPoslist);
+    char *p = *pp;
+    memcpy(p, *ppPoslist, n);
+    p += n;
+    *pp = p;
+  }
+  *ppPoslist = pEnd;
+}
+
+/*
+** Value used to signify the end of an position-list. This is safe because
+** it is not possible to have a document with 2^31 terms.
+*/
+#define POSITION_LIST_END 0x7fffffff
+
+/*
+** This function is used to help parse position-lists. When this function is
+** called, *pp may point to the start of the next varint in the position-list
+** being parsed, or it may point to 1 byte past the end of the position-list
+** (in which case **pp will be a terminator bytes POS_END (0) or
+** (1)).
+**
+** If *pp points past the end of the current position-list, set *pi to 
+** POSITION_LIST_END and return. Otherwise, read the next varint from *pp,
+** increment the current value of *pi by the value read, and set *pp to
+** point to the next value before returning.
+**
+** Before calling this routine *pi must be initialized to the value of
+** the previous position, or zero if we are reading the first position
+** in the position-list.  Because positions are delta-encoded, the value
+** of the previous position is needed in order to compute the value of
+** the next position.
+*/
+static void fts3ReadNextPos(
+  char **pp,                    /* IN/OUT: Pointer into position-list buffer */
+  sqlite3_int64 *pi             /* IN/OUT: Value read from position-list */
+){
+  if( (**pp)&0xFE ){
+    fts3GetDeltaVarint(pp, pi);
+    *pi -= 2;
+  }else{
+    *pi = POSITION_LIST_END;
+  }
+}
+
+/*
+** If parameter iCol is not 0, write an POS_COLUMN (1) byte followed by
+** the value of iCol encoded as a varint to *pp.   This will start a new
+** column list.
+**
+** Set *pp to point to the byte just after the last byte written before 
+** returning (do not modify it if iCol==0). Return the total number of bytes
+** written (0 if iCol==0).
+*/
+static int fts3PutColNumber(char **pp, int iCol){
+  int n = 0;                      /* Number of bytes written */
+  if( iCol ){
+    char *p = *pp;                /* Output pointer */
+    n = 1 + sqlite3Fts3PutVarint(&p[1], iCol);
+    *p = 0x01;
+    *pp = &p[n];
+  }
+  return n;
+}
+
+/*
+** Compute the union of two position lists.  The output written
+** into *pp contains all positions of both *pp1 and *pp2 in sorted
+** order and with any duplicates removed.  All pointers are
+** updated appropriately.   The caller is responsible for insuring
+** that there is enough space in *pp to hold the complete output.
+*/
+static void fts3PoslistMerge(
+  char **pp,                      /* Output buffer */
+  char **pp1,                     /* Left input list */
+  char **pp2                      /* Right input list */
+){
+  char *p = *pp;
+  char *p1 = *pp1;
+  char *p2 = *pp2;
+
+  while( *p1 || *p2 ){
+    int iCol1;         /* The current column index in pp1 */
+    int iCol2;         /* The current column index in pp2 */
+
+    if( *p1==POS_COLUMN ) fts3GetVarint32(&p1[1], &iCol1);
+    else if( *p1==POS_END ) iCol1 = POSITION_LIST_END;
+    else iCol1 = 0;
+
+    if( *p2==POS_COLUMN ) fts3GetVarint32(&p2[1], &iCol2);
+    else if( *p2==POS_END ) iCol2 = POSITION_LIST_END;
+    else iCol2 = 0;
+
+    if( iCol1==iCol2 ){
+      sqlite3_int64 i1 = 0;       /* Last position from pp1 */
+      sqlite3_int64 i2 = 0;       /* Last position from pp2 */
+      sqlite3_int64 iPrev = 0;
+      int n = fts3PutColNumber(&p, iCol1);
+      p1 += n;
+      p2 += n;
+
+      /* At this point, both p1 and p2 point to the start of column-lists
+      ** for the same column (the column with index iCol1 and iCol2).
+      ** A column-list is a list of non-negative delta-encoded varints, each 
+      ** incremented by 2 before being stored. Each list is terminated by a
+      ** POS_END (0) or POS_COLUMN (1). The following block merges the two lists
+      ** and writes the results to buffer p. p is left pointing to the byte
+      ** after the list written. No terminator (POS_END or POS_COLUMN) is
+      ** written to the output.
+      */
+      fts3GetDeltaVarint(&p1, &i1);
+      fts3GetDeltaVarint(&p2, &i2);
+      do {
+        fts3PutDeltaVarint(&p, &iPrev, (i1<i2) ? i1 : i2); 
+        iPrev -= 2;
+        if( i1==i2 ){
+          fts3ReadNextPos(&p1, &i1);
+          fts3ReadNextPos(&p2, &i2);
+        }else if( i1<i2 ){
+          fts3ReadNextPos(&p1, &i1);
+        }else{
+          fts3ReadNextPos(&p2, &i2);
+        }
+      }while( i1!=POSITION_LIST_END || i2!=POSITION_LIST_END );
+    }else if( iCol1<iCol2 ){
+      p1 += fts3PutColNumber(&p, iCol1);
+      fts3ColumnlistCopy(&p, &p1);
+    }else{
+      p2 += fts3PutColNumber(&p, iCol2);
+      fts3ColumnlistCopy(&p, &p2);
+    }
+  }
+
+  *p++ = POS_END;
+  *pp = p;
+  *pp1 = p1 + 1;
+  *pp2 = p2 + 1;
+}
+
+/*
+** This function is used to merge two position lists into one. When it is
+** called, *pp1 and *pp2 must both point to position lists. A position-list is
+** the part of a doclist that follows each document id. For example, if a row
+** contains:
+**
+**     'a b c'|'x y z'|'a b b a'
+**
+** Then the position list for this row for token 'b' would consist of:
+**
+**     0x02 0x01 0x02 0x03 0x03 0x00
+**
+** When this function returns, both *pp1 and *pp2 are left pointing to the
+** byte following the 0x00 terminator of their respective position lists.
+**
+** If isSaveLeft is 0, an entry is added to the output position list for 
+** each position in *pp2 for which there exists one or more positions in
+** *pp1 so that (pos(*pp2)>pos(*pp1) && pos(*pp2)-pos(*pp1)<=nToken). i.e.
+** when the *pp1 token appears before the *pp2 token, but not more than nToken
+** slots before it.
+**
+** e.g. nToken==1 searches for adjacent positions.
+*/
+static int fts3PoslistPhraseMerge(
+  char **pp,                      /* IN/OUT: Preallocated output buffer */
+  int nToken,                     /* Maximum difference in token positions */
+  int isSaveLeft,                 /* Save the left position */
+  int isExact,                    /* If *pp1 is exactly nTokens before *pp2 */
+  char **pp1,                     /* IN/OUT: Left input list */
+  char **pp2                      /* IN/OUT: Right input list */
+){
+  char *p = *pp;
+  char *p1 = *pp1;
+  char *p2 = *pp2;
+  int iCol1 = 0;
+  int iCol2 = 0;
+
+  /* Never set both isSaveLeft and isExact for the same invocation. */
+  assert( isSaveLeft==0 || isExact==0 );
+
+  assert( p!=0 && *p1!=0 && *p2!=0 );
+  if( *p1==POS_COLUMN ){ 
+    p1++;
+    p1 += fts3GetVarint32(p1, &iCol1);
+  }
+  if( *p2==POS_COLUMN ){ 
+    p2++;
+    p2 += fts3GetVarint32(p2, &iCol2);
+  }
+
+  while( 1 ){
+    if( iCol1==iCol2 ){
+      char *pSave = p;
+      sqlite3_int64 iPrev = 0;
+      sqlite3_int64 iPos1 = 0;
+      sqlite3_int64 iPos2 = 0;
+
+      if( iCol1 ){
+        *p++ = POS_COLUMN;
+        p += sqlite3Fts3PutVarint(p, iCol1);
+      }
+
+      assert( *p1!=POS_END && *p1!=POS_COLUMN );
+      assert( *p2!=POS_END && *p2!=POS_COLUMN );
+      fts3GetDeltaVarint(&p1, &iPos1); iPos1 -= 2;
+      fts3GetDeltaVarint(&p2, &iPos2); iPos2 -= 2;
+
+      while( 1 ){
+        if( iPos2==iPos1+nToken 
+         || (isExact==0 && iPos2>iPos1 && iPos2<=iPos1+nToken) 
+        ){
+          sqlite3_int64 iSave;
+          iSave = isSaveLeft ? iPos1 : iPos2;
+          fts3PutDeltaVarint(&p, &iPrev, iSave+2); iPrev -= 2;
+          pSave = 0;
+          assert( p );
+        }
+        if( (!isSaveLeft && iPos2<=(iPos1+nToken)) || iPos2<=iPos1 ){
+          if( (*p2&0xFE)==0 ) break;
+          fts3GetDeltaVarint(&p2, &iPos2); iPos2 -= 2;
+        }else{
+          if( (*p1&0xFE)==0 ) break;
+          fts3GetDeltaVarint(&p1, &iPos1); iPos1 -= 2;
+        }
+      }
+
+      if( pSave ){
+        assert( pp && p );
+        p = pSave;
+      }
+
+      fts3ColumnlistCopy(0, &p1);
+      fts3ColumnlistCopy(0, &p2);
+      assert( (*p1&0xFE)==0 && (*p2&0xFE)==0 );
+      if( 0==*p1 || 0==*p2 ) break;
+
+      p1++;
+      p1 += fts3GetVarint32(p1, &iCol1);
+      p2++;
+      p2 += fts3GetVarint32(p2, &iCol2);
+    }
+
+    /* Advance pointer p1 or p2 (whichever corresponds to the smaller of
+    ** iCol1 and iCol2) so that it points to either the 0x00 that marks the
+    ** end of the position list, or the 0x01 that precedes the next 
+    ** column-number in the position list. 
+    */
+    else if( iCol1<iCol2 ){
+      fts3ColumnlistCopy(0, &p1);
+      if( 0==*p1 ) break;
+      p1++;
+      p1 += fts3GetVarint32(p1, &iCol1);
+    }else{
+      fts3ColumnlistCopy(0, &p2);
+      if( 0==*p2 ) break;
+      p2++;
+      p2 += fts3GetVarint32(p2, &iCol2);
+    }
+  }
+
+  fts3PoslistCopy(0, &p2);
+  fts3PoslistCopy(0, &p1);
+  *pp1 = p1;
+  *pp2 = p2;
+  if( *pp==p ){
+    return 0;
+  }
+  *p++ = 0x00;
+  *pp = p;
+  return 1;
+}
+
+/*
+** Merge two position-lists as required by the NEAR operator. The argument
+** position lists correspond to the left and right phrases of an expression 
+** like:
+**
+**     "phrase 1" NEAR "phrase number 2"
+**
+** Position list *pp1 corresponds to the left-hand side of the NEAR 
+** expression and *pp2 to the right. As usual, the indexes in the position 
+** lists are the offsets of the last token in each phrase (tokens "1" and "2" 
+** in the example above).
+**
+** The output position list - written to *pp - is a copy of *pp2 with those
+** entries that are not sufficiently NEAR entries in *pp1 removed.
+*/
+static int fts3PoslistNearMerge(
+  char **pp,                      /* Output buffer */
+  char *aTmp,                     /* Temporary buffer space */
+  int nRight,                     /* Maximum difference in token positions */
+  int nLeft,                      /* Maximum difference in token positions */
+  char **pp1,                     /* IN/OUT: Left input list */
+  char **pp2                      /* IN/OUT: Right input list */
+){
+  char *p1 = *pp1;
+  char *p2 = *pp2;
+
+  char *pTmp1 = aTmp;
+  char *pTmp2;
+  char *aTmp2;
+  int res = 1;
+
+  fts3PoslistPhraseMerge(&pTmp1, nRight, 0, 0, pp1, pp2);
+  aTmp2 = pTmp2 = pTmp1;
+  *pp1 = p1;
+  *pp2 = p2;
+  fts3PoslistPhraseMerge(&pTmp2, nLeft, 1, 0, pp2, pp1);
+  if( pTmp1!=aTmp && pTmp2!=aTmp2 ){
+    fts3PoslistMerge(pp, &aTmp, &aTmp2);
+  }else if( pTmp1!=aTmp ){
+    fts3PoslistCopy(pp, &aTmp);
+  }else if( pTmp2!=aTmp2 ){
+    fts3PoslistCopy(pp, &aTmp2);
+  }else{
+    res = 0;
+  }
+
+  return res;
+}
+
+/* 
+** An instance of this function is used to merge together the (potentially
+** large number of) doclists for each term that matches a prefix query.
+** See function fts3TermSelectMerge() for details.
+*/
+typedef struct TermSelect TermSelect;
+struct TermSelect {
+  char *aaOutput[16];             /* Malloc'd output buffers */
+  int anOutput[16];               /* Size each output buffer in bytes */
+};
+
+/*
+** This function is used to read a single varint from a buffer. Parameter
+** pEnd points 1 byte past the end of the buffer. When this function is
+** called, if *pp points to pEnd or greater, then the end of the buffer
+** has been reached. In this case *pp is set to 0 and the function returns.
+**
+** If *pp does not point to or past pEnd, then a single varint is read
+** from *pp. *pp is then set to point 1 byte past the end of the read varint.
+**
+** If bDescIdx is false, the value read is added to *pVal before returning.
+** If it is true, the value read is subtracted from *pVal before this 
+** function returns.
+*/
+static void fts3GetDeltaVarint3(
+  char **pp,                      /* IN/OUT: Point to read varint from */
+  char *pEnd,                     /* End of buffer */
+  int bDescIdx,                   /* True if docids are descending */
+  sqlite3_int64 *pVal             /* IN/OUT: Integer value */
+){
+  if( *pp>=pEnd ){
+    *pp = 0;
+  }else{
+    sqlite3_int64 iVal;
+    *pp += sqlite3Fts3GetVarint(*pp, &iVal);
+    if( bDescIdx ){
+      *pVal -= iVal;
+    }else{
+      *pVal += iVal;
+    }
+  }
+}
+
+/*
+** This function is used to write a single varint to a buffer. The varint
+** is written to *pp. Before returning, *pp is set to point 1 byte past the
+** end of the value written.
+**
+** If *pbFirst is zero when this function is called, the value written to
+** the buffer is that of parameter iVal. 
+**
+** If *pbFirst is non-zero when this function is called, then the value 
+** written is either (iVal-*piPrev) (if bDescIdx is zero) or (*piPrev-iVal)
+** (if bDescIdx is non-zero).
+**
+** Before returning, this function always sets *pbFirst to 1 and *piPrev
+** to the value of parameter iVal.
+*/
+static void fts3PutDeltaVarint3(
+  char **pp,                      /* IN/OUT: Output pointer */
+  int bDescIdx,                   /* True for descending docids */
+  sqlite3_int64 *piPrev,          /* IN/OUT: Previous value written to list */
+  int *pbFirst,                   /* IN/OUT: True after first int written */
+  sqlite3_int64 iVal              /* Write this value to the list */
+){
+  sqlite3_int64 iWrite;
+  if( bDescIdx==0 || *pbFirst==0 ){
+    iWrite = iVal - *piPrev;
+  }else{
+    iWrite = *piPrev - iVal;
+  }
+  assert( *pbFirst || *piPrev==0 );
+  assert( *pbFirst==0 || iWrite>0 );
+  *pp += sqlite3Fts3PutVarint(*pp, iWrite);
+  *piPrev = iVal;
+  *pbFirst = 1;
+}
+
+
+/*
+** This macro is used by various functions that merge doclists. The two
+** arguments are 64-bit docid values. If the value of the stack variable
+** bDescDoclist is 0 when this macro is invoked, then it returns (i1-i2). 
+** Otherwise, (i2-i1).
+**
+** Using this makes it easier to write code that can merge doclists that are
+** sorted in either ascending or descending order.
+*/
+#define DOCID_CMP(i1, i2) ((bDescDoclist?-1:1) * (i1-i2))
+
+/*
+** This function does an "OR" merge of two doclists (output contains all
+** positions contained in either argument doclist). If the docids in the 
+** input doclists are sorted in ascending order, parameter bDescDoclist
+** should be false. If they are sorted in ascending order, it should be
+** passed a non-zero value.
+**
+** If no error occurs, *paOut is set to point at an sqlite3_malloc'd buffer
+** containing the output doclist and SQLITE_OK is returned. In this case
+** *pnOut is set to the number of bytes in the output doclist.
+**
+** If an error occurs, an SQLite error code is returned. The output values
+** are undefined in this case.
+*/
+static int fts3DoclistOrMerge(
+  int bDescDoclist,               /* True if arguments are desc */
+  char *a1, int n1,               /* First doclist */
+  char *a2, int n2,               /* Second doclist */
+  char **paOut, int *pnOut        /* OUT: Malloc'd doclist */
+){
+  sqlite3_int64 i1 = 0;
+  sqlite3_int64 i2 = 0;
+  sqlite3_int64 iPrev = 0;
+  char *pEnd1 = &a1[n1];
+  char *pEnd2 = &a2[n2];
+  char *p1 = a1;
+  char *p2 = a2;
+  char *p;
+  char *aOut;
+  int bFirstOut = 0;
+
+  *paOut = 0;
+  *pnOut = 0;
+
+  /* Allocate space for the output. Both the input and output doclists
+  ** are delta encoded. If they are in ascending order (bDescDoclist==0),
+  ** then the first docid in each list is simply encoded as a varint. For
+  ** each subsequent docid, the varint stored is the difference between the
+  ** current and previous docid (a positive number - since the list is in
+  ** ascending order).
+  **
+  ** The first docid written to the output is therefore encoded using the 
+  ** same number of bytes as it is in whichever of the input lists it is
+  ** read from. And each subsequent docid read from the same input list 
+  ** consumes either the same or less bytes as it did in the input (since
+  ** the difference between it and the previous value in the output must
+  ** be a positive value less than or equal to the delta value read from 
+  ** the input list). The same argument applies to all but the first docid
+  ** read from the 'other' list. And to the contents of all position lists
+  ** that will be copied and merged from the input to the output.
+  **
+  ** However, if the first docid copied to the output is a negative number,
+  ** then the encoding of the first docid from the 'other' input list may
+  ** be larger in the output than it was in the input (since the delta value
+  ** may be a larger positive integer than the actual docid).
+  **
+  ** The space required to store the output is therefore the sum of the
+  ** sizes of the two inputs, plus enough space for exactly one of the input
+  ** docids to grow. 
+  **
+  ** A symetric argument may be made if the doclists are in descending 
+  ** order.
+  */
+  aOut = sqlite3_malloc(n1+n2+FTS3_VARINT_MAX-1);
+  if( !aOut ) return SQLITE_NOMEM;
+
+  p = aOut;
+  fts3GetDeltaVarint3(&p1, pEnd1, 0, &i1);
+  fts3GetDeltaVarint3(&p2, pEnd2, 0, &i2);
+  while( p1 || p2 ){
+    sqlite3_int64 iDiff = DOCID_CMP(i1, i2);
+
+    if( p2 && p1 && iDiff==0 ){
+      fts3PutDeltaVarint3(&p, bDescDoclist, &iPrev, &bFirstOut, i1);
+      fts3PoslistMerge(&p, &p1, &p2);
+      fts3GetDeltaVarint3(&p1, pEnd1, bDescDoclist, &i1);
+      fts3GetDeltaVarint3(&p2, pEnd2, bDescDoclist, &i2);
+    }else if( !p2 || (p1 && iDiff<0) ){
+      fts3PutDeltaVarint3(&p, bDescDoclist, &iPrev, &bFirstOut, i1);
+      fts3PoslistCopy(&p, &p1);
+      fts3GetDeltaVarint3(&p1, pEnd1, bDescDoclist, &i1);
+    }else{
+      fts3PutDeltaVarint3(&p, bDescDoclist, &iPrev, &bFirstOut, i2);
+      fts3PoslistCopy(&p, &p2);
+      fts3GetDeltaVarint3(&p2, pEnd2, bDescDoclist, &i2);
+    }
+  }
+
+  *paOut = aOut;
+  *pnOut = (int)(p-aOut);
+  assert( *pnOut<=n1+n2+FTS3_VARINT_MAX-1 );
+  return SQLITE_OK;
+}
+
+/*
+** This function does a "phrase" merge of two doclists. In a phrase merge,
+** the output contains a copy of each position from the right-hand input
+** doclist for which there is a position in the left-hand input doclist
+** exactly nDist tokens before it.
+**
+** If the docids in the input doclists are sorted in ascending order,
+** parameter bDescDoclist should be false. If they are sorted in ascending 
+** order, it should be passed a non-zero value.
+**
+** The right-hand input doclist is overwritten by this function.
+*/
+static int fts3DoclistPhraseMerge(
+  int bDescDoclist,               /* True if arguments are desc */
+  int nDist,                      /* Distance from left to right (1=adjacent) */
+  char *aLeft, int nLeft,         /* Left doclist */
+  char **paRight, int *pnRight    /* IN/OUT: Right/output doclist */
+){
+  sqlite3_int64 i1 = 0;
+  sqlite3_int64 i2 = 0;
+  sqlite3_int64 iPrev = 0;
+  char *aRight = *paRight;
+  char *pEnd1 = &aLeft[nLeft];
+  char *pEnd2 = &aRight[*pnRight];
+  char *p1 = aLeft;
+  char *p2 = aRight;
+  char *p;
+  int bFirstOut = 0;
+  char *aOut;
+
+  assert( nDist>0 );
+  if( bDescDoclist ){
+    aOut = sqlite3_malloc(*pnRight + FTS3_VARINT_MAX);
+    if( aOut==0 ) return SQLITE_NOMEM;
+  }else{
+    aOut = aRight;
+  }
+  p = aOut;
+
+  fts3GetDeltaVarint3(&p1, pEnd1, 0, &i1);
+  fts3GetDeltaVarint3(&p2, pEnd2, 0, &i2);
+
+  while( p1 && p2 ){
+    sqlite3_int64 iDiff = DOCID_CMP(i1, i2);
+    if( iDiff==0 ){
+      char *pSave = p;
+      sqlite3_int64 iPrevSave = iPrev;
+      int bFirstOutSave = bFirstOut;
+
+      fts3PutDeltaVarint3(&p, bDescDoclist, &iPrev, &bFirstOut, i1);
+      if( 0==fts3PoslistPhraseMerge(&p, nDist, 0, 1, &p1, &p2) ){
+        p = pSave;
+        iPrev = iPrevSave;
+        bFirstOut = bFirstOutSave;
+      }
+      fts3GetDeltaVarint3(&p1, pEnd1, bDescDoclist, &i1);
+      fts3GetDeltaVarint3(&p2, pEnd2, bDescDoclist, &i2);
+    }else if( iDiff<0 ){
+      fts3PoslistCopy(0, &p1);
+      fts3GetDeltaVarint3(&p1, pEnd1, bDescDoclist, &i1);
+    }else{
+      fts3PoslistCopy(0, &p2);
+      fts3GetDeltaVarint3(&p2, pEnd2, bDescDoclist, &i2);
+    }
+  }
+
+  *pnRight = (int)(p - aOut);
+  if( bDescDoclist ){
+    sqlite3_free(aRight);
+    *paRight = aOut;
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Argument pList points to a position list nList bytes in size. This
+** function checks to see if the position list contains any entries for
+** a token in position 0 (of any column). If so, it writes argument iDelta
+** to the output buffer pOut, followed by a position list consisting only
+** of the entries from pList at position 0, and terminated by an 0x00 byte.
+** The value returned is the number of bytes written to pOut (if any).
+*/
+SQLITE_PRIVATE int sqlite3Fts3FirstFilter(
+  sqlite3_int64 iDelta,           /* Varint that may be written to pOut */
+  char *pList,                    /* Position list (no 0x00 term) */
+  int nList,                      /* Size of pList in bytes */
+  char *pOut                      /* Write output here */
+){
+  int nOut = 0;
+  int bWritten = 0;               /* True once iDelta has been written */
+  char *p = pList;
+  char *pEnd = &pList[nList];
+
+  if( *p!=0x01 ){
+    if( *p==0x02 ){
+      nOut += sqlite3Fts3PutVarint(&pOut[nOut], iDelta);
+      pOut[nOut++] = 0x02;
+      bWritten = 1;
+    }
+    fts3ColumnlistCopy(0, &p);
+  }
+
+  while( p<pEnd && *p==0x01 ){
+    sqlite3_int64 iCol;
+    p++;
+    p += sqlite3Fts3GetVarint(p, &iCol);
+    if( *p==0x02 ){
+      if( bWritten==0 ){
+        nOut += sqlite3Fts3PutVarint(&pOut[nOut], iDelta);
+        bWritten = 1;
+      }
+      pOut[nOut++] = 0x01;
+      nOut += sqlite3Fts3PutVarint(&pOut[nOut], iCol);
+      pOut[nOut++] = 0x02;
+    }
+    fts3ColumnlistCopy(0, &p);
+  }
+  if( bWritten ){
+    pOut[nOut++] = 0x00;
+  }
+
+  return nOut;
+}
+
+
+/*
+** Merge all doclists in the TermSelect.aaOutput[] array into a single
+** doclist stored in TermSelect.aaOutput[0]. If successful, delete all
+** other doclists (except the aaOutput[0] one) and return SQLITE_OK.
+**
+** If an OOM error occurs, return SQLITE_NOMEM. In this case it is
+** the responsibility of the caller to free any doclists left in the
+** TermSelect.aaOutput[] array.
+*/
+static int fts3TermSelectFinishMerge(Fts3Table *p, TermSelect *pTS){
+  char *aOut = 0;
+  int nOut = 0;
+  int i;
+
+  /* Loop through the doclists in the aaOutput[] array. Merge them all
+  ** into a single doclist.
+  */
+  for(i=0; i<SizeofArray(pTS->aaOutput); i++){
+    if( pTS->aaOutput[i] ){
+      if( !aOut ){
+        aOut = pTS->aaOutput[i];
+        nOut = pTS->anOutput[i];
+        pTS->aaOutput[i] = 0;
+      }else{
+        int nNew;
+        char *aNew;
+
+        int rc = fts3DoclistOrMerge(p->bDescIdx, 
+            pTS->aaOutput[i], pTS->anOutput[i], aOut, nOut, &aNew, &nNew
+        );
+        if( rc!=SQLITE_OK ){
+          sqlite3_free(aOut);
+          return rc;
+        }
+
+        sqlite3_free(pTS->aaOutput[i]);
+        sqlite3_free(aOut);
+        pTS->aaOutput[i] = 0;
+        aOut = aNew;
+        nOut = nNew;
+      }
+    }
+  }
+
+  pTS->aaOutput[0] = aOut;
+  pTS->anOutput[0] = nOut;
+  return SQLITE_OK;
+}
+
+/*
+** Merge the doclist aDoclist/nDoclist into the TermSelect object passed
+** as the first argument. The merge is an "OR" merge (see function
+** fts3DoclistOrMerge() for details).
+**
+** This function is called with the doclist for each term that matches
+** a queried prefix. It merges all these doclists into one, the doclist
+** for the specified prefix. Since there can be a very large number of
+** doclists to merge, the merging is done pair-wise using the TermSelect
+** object.
+**
+** This function returns SQLITE_OK if the merge is successful, or an
+** SQLite error code (SQLITE_NOMEM) if an error occurs.
+*/
+static int fts3TermSelectMerge(
+  Fts3Table *p,                   /* FTS table handle */
+  TermSelect *pTS,                /* TermSelect object to merge into */
+  char *aDoclist,                 /* Pointer to doclist */
+  int nDoclist                    /* Size of aDoclist in bytes */
+){
+  if( pTS->aaOutput[0]==0 ){
+    /* If this is the first term selected, copy the doclist to the output
+    ** buffer using memcpy(). 
+    **
+    ** Add FTS3_VARINT_MAX bytes of unused space to the end of the 
+    ** allocation. This is so as to ensure that the buffer is big enough
+    ** to hold the current doclist AND'd with any other doclist. If the
+    ** doclists are stored in order=ASC order, this padding would not be
+    ** required (since the size of [doclistA AND doclistB] is always less
+    ** than or equal to the size of [doclistA] in that case). But this is
+    ** not true for order=DESC. For example, a doclist containing (1, -1) 
+    ** may be smaller than (-1), as in the first example the -1 may be stored
+    ** as a single-byte delta, whereas in the second it must be stored as a
+    ** FTS3_VARINT_MAX byte varint.
+    **
+    ** Similar padding is added in the fts3DoclistOrMerge() function.
+    */
+    pTS->aaOutput[0] = sqlite3_malloc(nDoclist + FTS3_VARINT_MAX + 1);
+    pTS->anOutput[0] = nDoclist;
+    if( pTS->aaOutput[0] ){
+      memcpy(pTS->aaOutput[0], aDoclist, nDoclist);
+    }else{
+      return SQLITE_NOMEM;
+    }
+  }else{
+    char *aMerge = aDoclist;
+    int nMerge = nDoclist;
+    int iOut;
+
+    for(iOut=0; iOut<SizeofArray(pTS->aaOutput); iOut++){
+      if( pTS->aaOutput[iOut]==0 ){
+        assert( iOut>0 );
+        pTS->aaOutput[iOut] = aMerge;
+        pTS->anOutput[iOut] = nMerge;
+        break;
+      }else{
+        char *aNew;
+        int nNew;
+
+        int rc = fts3DoclistOrMerge(p->bDescIdx, aMerge, nMerge, 
+            pTS->aaOutput[iOut], pTS->anOutput[iOut], &aNew, &nNew
+        );
+        if( rc!=SQLITE_OK ){
+          if( aMerge!=aDoclist ) sqlite3_free(aMerge);
+          return rc;
+        }
+
+        if( aMerge!=aDoclist ) sqlite3_free(aMerge);
+        sqlite3_free(pTS->aaOutput[iOut]);
+        pTS->aaOutput[iOut] = 0;
+  
+        aMerge = aNew;
+        nMerge = nNew;
+        if( (iOut+1)==SizeofArray(pTS->aaOutput) ){
+          pTS->aaOutput[iOut] = aMerge;
+          pTS->anOutput[iOut] = nMerge;
+        }
+      }
+    }
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Append SegReader object pNew to the end of the pCsr->apSegment[] array.
+*/
+static int fts3SegReaderCursorAppend(
+  Fts3MultiSegReader *pCsr, 
+  Fts3SegReader *pNew
+){
+  if( (pCsr->nSegment%16)==0 ){
+    Fts3SegReader **apNew;
+    int nByte = (pCsr->nSegment + 16)*sizeof(Fts3SegReader*);
+    apNew = (Fts3SegReader **)sqlite3_realloc(pCsr->apSegment, nByte);
+    if( !apNew ){
+      sqlite3Fts3SegReaderFree(pNew);
+      return SQLITE_NOMEM;
+    }
+    pCsr->apSegment = apNew;
+  }
+  pCsr->apSegment[pCsr->nSegment++] = pNew;
+  return SQLITE_OK;
+}
+
+/*
+** Add seg-reader objects to the Fts3MultiSegReader object passed as the
+** 8th argument.
+**
+** This function returns SQLITE_OK if successful, or an SQLite error code
+** otherwise.
+*/
+static int fts3SegReaderCursor(
+  Fts3Table *p,                   /* FTS3 table handle */
+  int iLangid,                    /* Language id */
+  int iIndex,                     /* Index to search (from 0 to p->nIndex-1) */
+  int iLevel,                     /* Level of segments to scan */
+  const char *zTerm,              /* Term to query for */
+  int nTerm,                      /* Size of zTerm in bytes */
+  int isPrefix,                   /* True for a prefix search */
+  int isScan,                     /* True to scan from zTerm to EOF */
+  Fts3MultiSegReader *pCsr        /* Cursor object to populate */
+){
+  int rc = SQLITE_OK;             /* Error code */
+  sqlite3_stmt *pStmt = 0;        /* Statement to iterate through segments */
+  int rc2;                        /* Result of sqlite3_reset() */
+
+  /* If iLevel is less than 0 and this is not a scan, include a seg-reader 
+  ** for the pending-terms. If this is a scan, then this call must be being
+  ** made by an fts4aux module, not an FTS table. In this case calling
+  ** Fts3SegReaderPending might segfault, as the data structures used by 
+  ** fts4aux are not completely populated. So it's easiest to filter these
+  ** calls out here.  */
+  if( iLevel<0 && p->aIndex ){
+    Fts3SegReader *pSeg = 0;
+    rc = sqlite3Fts3SegReaderPending(p, iIndex, zTerm, nTerm, isPrefix||isScan, &pSeg);
+    if( rc==SQLITE_OK && pSeg ){
+      rc = fts3SegReaderCursorAppend(pCsr, pSeg);
+    }
+  }
+
+  if( iLevel!=FTS3_SEGCURSOR_PENDING ){
+    if( rc==SQLITE_OK ){
+      rc = sqlite3Fts3AllSegdirs(p, iLangid, iIndex, iLevel, &pStmt);
+    }
+
+    while( rc==SQLITE_OK && SQLITE_ROW==(rc = sqlite3_step(pStmt)) ){
+      Fts3SegReader *pSeg = 0;
+
+      /* Read the values returned by the SELECT into local variables. */
+      sqlite3_int64 iStartBlock = sqlite3_column_int64(pStmt, 1);
+      sqlite3_int64 iLeavesEndBlock = sqlite3_column_int64(pStmt, 2);
+      sqlite3_int64 iEndBlock = sqlite3_column_int64(pStmt, 3);
+      int nRoot = sqlite3_column_bytes(pStmt, 4);
+      char const *zRoot = sqlite3_column_blob(pStmt, 4);
+
+      /* If zTerm is not NULL, and this segment is not stored entirely on its
+      ** root node, the range of leaves scanned can be reduced. Do this. */
+      if( iStartBlock && zTerm ){
+        sqlite3_int64 *pi = (isPrefix ? &iLeavesEndBlock : 0);
+        rc = fts3SelectLeaf(p, zTerm, nTerm, zRoot, nRoot, &iStartBlock, pi);
+        if( rc!=SQLITE_OK ) goto finished;
+        if( isPrefix==0 && isScan==0 ) iLeavesEndBlock = iStartBlock;
+      }
+ 
+      rc = sqlite3Fts3SegReaderNew(pCsr->nSegment+1, 
+          (isPrefix==0 && isScan==0),
+          iStartBlock, iLeavesEndBlock, 
+          iEndBlock, zRoot, nRoot, &pSeg
+      );
+      if( rc!=SQLITE_OK ) goto finished;
+      rc = fts3SegReaderCursorAppend(pCsr, pSeg);
+    }
+  }
+
+ finished:
+  rc2 = sqlite3_reset(pStmt);
+  if( rc==SQLITE_DONE ) rc = rc2;
+
+  return rc;
+}
+
+/*
+** Set up a cursor object for iterating through a full-text index or a 
+** single level therein.
+*/
+SQLITE_PRIVATE int sqlite3Fts3SegReaderCursor(
+  Fts3Table *p,                   /* FTS3 table handle */
+  int iLangid,                    /* Language-id to search */
+  int iIndex,                     /* Index to search (from 0 to p->nIndex-1) */
+  int iLevel,                     /* Level of segments to scan */
+  const char *zTerm,              /* Term to query for */
+  int nTerm,                      /* Size of zTerm in bytes */
+  int isPrefix,                   /* True for a prefix search */
+  int isScan,                     /* True to scan from zTerm to EOF */
+  Fts3MultiSegReader *pCsr       /* Cursor object to populate */
+){
+  assert( iIndex>=0 && iIndex<p->nIndex );
+  assert( iLevel==FTS3_SEGCURSOR_ALL
+      ||  iLevel==FTS3_SEGCURSOR_PENDING 
+      ||  iLevel>=0
+  );
+  assert( iLevel<FTS3_SEGDIR_MAXLEVEL );
+  assert( FTS3_SEGCURSOR_ALL<0 && FTS3_SEGCURSOR_PENDING<0 );
+  assert( isPrefix==0 || isScan==0 );
+
+  memset(pCsr, 0, sizeof(Fts3MultiSegReader));
+  return fts3SegReaderCursor(
+      p, iLangid, iIndex, iLevel, zTerm, nTerm, isPrefix, isScan, pCsr
+  );
+}
+
+/*
+** In addition to its current configuration, have the Fts3MultiSegReader
+** passed as the 4th argument also scan the doclist for term zTerm/nTerm.
+**
+** SQLITE_OK is returned if no error occurs, otherwise an SQLite error code.
+*/
+static int fts3SegReaderCursorAddZero(
+  Fts3Table *p,                   /* FTS virtual table handle */
+  int iLangid,
+  const char *zTerm,              /* Term to scan doclist of */
+  int nTerm,                      /* Number of bytes in zTerm */
+  Fts3MultiSegReader *pCsr        /* Fts3MultiSegReader to modify */
+){
+  return fts3SegReaderCursor(p, 
+      iLangid, 0, FTS3_SEGCURSOR_ALL, zTerm, nTerm, 0, 0,pCsr
+  );
+}
+
+/*
+** Open an Fts3MultiSegReader to scan the doclist for term zTerm/nTerm. Or,
+** if isPrefix is true, to scan the doclist for all terms for which 
+** zTerm/nTerm is a prefix. If successful, return SQLITE_OK and write
+** a pointer to the new Fts3MultiSegReader to *ppSegcsr. Otherwise, return
+** an SQLite error code.
+**
+** It is the responsibility of the caller to free this object by eventually
+** passing it to fts3SegReaderCursorFree() 
+**
+** SQLITE_OK is returned if no error occurs, otherwise an SQLite error code.
+** Output parameter *ppSegcsr is set to 0 if an error occurs.
+*/
+static int fts3TermSegReaderCursor(
+  Fts3Cursor *pCsr,               /* Virtual table cursor handle */
+  const char *zTerm,              /* Term to query for */
+  int nTerm,                      /* Size of zTerm in bytes */
+  int isPrefix,                   /* True for a prefix search */
+  Fts3MultiSegReader **ppSegcsr   /* OUT: Allocated seg-reader cursor */
+){
+  Fts3MultiSegReader *pSegcsr;    /* Object to allocate and return */
+  int rc = SQLITE_NOMEM;          /* Return code */
+
+  pSegcsr = sqlite3_malloc(sizeof(Fts3MultiSegReader));
+  if( pSegcsr ){
+    int i;
+    int bFound = 0;               /* True once an index has been found */
+    Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
+
+    if( isPrefix ){
+      for(i=1; bFound==0 && i<p->nIndex; i++){
+        if( p->aIndex[i].nPrefix==nTerm ){
+          bFound = 1;
+          rc = sqlite3Fts3SegReaderCursor(p, pCsr->iLangid, 
+              i, FTS3_SEGCURSOR_ALL, zTerm, nTerm, 0, 0, pSegcsr
+          );
+          pSegcsr->bLookup = 1;
+        }
+      }
+
+      for(i=1; bFound==0 && i<p->nIndex; i++){
+        if( p->aIndex[i].nPrefix==nTerm+1 ){
+          bFound = 1;
+          rc = sqlite3Fts3SegReaderCursor(p, pCsr->iLangid, 
+              i, FTS3_SEGCURSOR_ALL, zTerm, nTerm, 1, 0, pSegcsr
+          );
+          if( rc==SQLITE_OK ){
+            rc = fts3SegReaderCursorAddZero(
+                p, pCsr->iLangid, zTerm, nTerm, pSegcsr
+            );
+          }
+        }
+      }
+    }
+
+    if( bFound==0 ){
+      rc = sqlite3Fts3SegReaderCursor(p, pCsr->iLangid, 
+          0, FTS3_SEGCURSOR_ALL, zTerm, nTerm, isPrefix, 0, pSegcsr
+      );
+      pSegcsr->bLookup = !isPrefix;
+    }
+  }
+
+  *ppSegcsr = pSegcsr;
+  return rc;
+}
+
+/*
+** Free an Fts3MultiSegReader allocated by fts3TermSegReaderCursor().
+*/
+static void fts3SegReaderCursorFree(Fts3MultiSegReader *pSegcsr){
+  sqlite3Fts3SegReaderFinish(pSegcsr);
+  sqlite3_free(pSegcsr);
+}
+
+/*
+** This function retrieves the doclist for the specified term (or term
+** prefix) from the database.
+*/
+static int fts3TermSelect(
+  Fts3Table *p,                   /* Virtual table handle */
+  Fts3PhraseToken *pTok,          /* Token to query for */
+  int iColumn,                    /* Column to query (or -ve for all columns) */
+  int *pnOut,                     /* OUT: Size of buffer at *ppOut */
+  char **ppOut                    /* OUT: Malloced result buffer */
+){
+  int rc;                         /* Return code */
+  Fts3MultiSegReader *pSegcsr;    /* Seg-reader cursor for this term */
+  TermSelect tsc;                 /* Object for pair-wise doclist merging */
+  Fts3SegFilter filter;           /* Segment term filter configuration */
+
+  pSegcsr = pTok->pSegcsr;
+  memset(&tsc, 0, sizeof(TermSelect));
+
+  filter.flags = FTS3_SEGMENT_IGNORE_EMPTY | FTS3_SEGMENT_REQUIRE_POS
+        | (pTok->isPrefix ? FTS3_SEGMENT_PREFIX : 0)
+        | (pTok->bFirst ? FTS3_SEGMENT_FIRST : 0)
+        | (iColumn<p->nColumn ? FTS3_SEGMENT_COLUMN_FILTER : 0);
+  filter.iCol = iColumn;
+  filter.zTerm = pTok->z;
+  filter.nTerm = pTok->n;
+
+  rc = sqlite3Fts3SegReaderStart(p, pSegcsr, &filter);
+  while( SQLITE_OK==rc
+      && SQLITE_ROW==(rc = sqlite3Fts3SegReaderStep(p, pSegcsr)) 
+  ){
+    rc = fts3TermSelectMerge(p, &tsc, pSegcsr->aDoclist, pSegcsr->nDoclist);
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = fts3TermSelectFinishMerge(p, &tsc);
+  }
+  if( rc==SQLITE_OK ){
+    *ppOut = tsc.aaOutput[0];
+    *pnOut = tsc.anOutput[0];
+  }else{
+    int i;
+    for(i=0; i<SizeofArray(tsc.aaOutput); i++){
+      sqlite3_free(tsc.aaOutput[i]);
+    }
+  }
+
+  fts3SegReaderCursorFree(pSegcsr);
+  pTok->pSegcsr = 0;
+  return rc;
+}
+
+/*
+** This function counts the total number of docids in the doclist stored
+** in buffer aList[], size nList bytes.
+**
+** If the isPoslist argument is true, then it is assumed that the doclist
+** contains a position-list following each docid. Otherwise, it is assumed
+** that the doclist is simply a list of docids stored as delta encoded 
+** varints.
+*/
+static int fts3DoclistCountDocids(char *aList, int nList){
+  int nDoc = 0;                   /* Return value */
+  if( aList ){
+    char *aEnd = &aList[nList];   /* Pointer to one byte after EOF */
+    char *p = aList;              /* Cursor */
+    while( p<aEnd ){
+      nDoc++;
+      while( (*p++)&0x80 );     /* Skip docid varint */
+      fts3PoslistCopy(0, &p);   /* Skip over position list */
+    }
+  }
+
+  return nDoc;
+}
+
+/*
+** Advance the cursor to the next row in the %_content table that
+** matches the search criteria.  For a MATCH search, this will be
+** the next row that matches. For a full-table scan, this will be
+** simply the next row in the %_content table.  For a docid lookup,
+** this routine simply sets the EOF flag.
+**
+** Return SQLITE_OK if nothing goes wrong.  SQLITE_OK is returned
+** even if we reach end-of-file.  The fts3EofMethod() will be called
+** subsequently to determine whether or not an EOF was hit.
+*/
+static int fts3NextMethod(sqlite3_vtab_cursor *pCursor){
+  int rc;
+  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;
+  if( pCsr->eSearch==FTS3_DOCID_SEARCH || pCsr->eSearch==FTS3_FULLSCAN_SEARCH ){
+    if( SQLITE_ROW!=sqlite3_step(pCsr->pStmt) ){
+      pCsr->isEof = 1;
+      rc = sqlite3_reset(pCsr->pStmt);
+    }else{
+      pCsr->iPrevId = sqlite3_column_int64(pCsr->pStmt, 0);
+      rc = SQLITE_OK;
+    }
+  }else{
+    rc = fts3EvalNext((Fts3Cursor *)pCursor);
+  }
+  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
+  return rc;
+}
+
+/*
+** The following are copied from sqliteInt.h.
+**
+** Constants for the largest and smallest possible 64-bit signed integers.
+** These macros are designed to work correctly on both 32-bit and 64-bit
+** compilers.
+*/
+#ifndef SQLITE_AMALGAMATION
+# define LARGEST_INT64  (0xffffffff|(((sqlite3_int64)0x7fffffff)<<32))
+# define SMALLEST_INT64 (((sqlite3_int64)-1) - LARGEST_INT64)
+#endif
+
+/*
+** If the numeric type of argument pVal is "integer", then return it
+** converted to a 64-bit signed integer. Otherwise, return a copy of
+** the second parameter, iDefault.
+*/
+static sqlite3_int64 fts3DocidRange(sqlite3_value *pVal, i64 iDefault){
+  if( pVal ){
+    int eType = sqlite3_value_numeric_type(pVal);
+    if( eType==SQLITE_INTEGER ){
+      return sqlite3_value_int64(pVal);
+    }
+  }
+  return iDefault;
+}
+
+/*
+** This is the xFilter interface for the virtual table.  See
+** the virtual table xFilter method documentation for additional
+** information.
+**
+** If idxNum==FTS3_FULLSCAN_SEARCH then do a full table scan against
+** the %_content table.
+**
+** If idxNum==FTS3_DOCID_SEARCH then do a docid lookup for a single entry
+** in the %_content table.
+**
+** If idxNum>=FTS3_FULLTEXT_SEARCH then use the full text index.  The
+** column on the left-hand side of the MATCH operator is column
+** number idxNum-FTS3_FULLTEXT_SEARCH, 0 indexed.  argv[0] is the right-hand
+** side of the MATCH operator.
+*/
+static int fts3FilterMethod(
+  sqlite3_vtab_cursor *pCursor,   /* The cursor used for this query */
+  int idxNum,                     /* Strategy index */
+  const char *idxStr,             /* Unused */
+  int nVal,                       /* Number of elements in apVal */
+  sqlite3_value **apVal           /* Arguments for the indexing scheme */
+){
+  int rc = SQLITE_OK;
+  char *zSql;                     /* SQL statement used to access %_content */
+  int eSearch;
+  Fts3Table *p = (Fts3Table *)pCursor->pVtab;
+  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;
+
+  sqlite3_value *pCons = 0;       /* The MATCH or rowid constraint, if any */
+  sqlite3_value *pLangid = 0;     /* The "langid = ?" constraint, if any */
+  sqlite3_value *pDocidGe = 0;    /* The "docid >= ?" constraint, if any */
+  sqlite3_value *pDocidLe = 0;    /* The "docid <= ?" constraint, if any */
+  int iIdx;
+
+  UNUSED_PARAMETER(idxStr);
+  UNUSED_PARAMETER(nVal);
+
+  eSearch = (idxNum & 0x0000FFFF);
+  assert( eSearch>=0 && eSearch<=(FTS3_FULLTEXT_SEARCH+p->nColumn) );
+  assert( p->pSegments==0 );
+
+  /* Collect arguments into local variables */
+  iIdx = 0;
+  if( eSearch!=FTS3_FULLSCAN_SEARCH ) pCons = apVal[iIdx++];
+  if( idxNum & FTS3_HAVE_LANGID ) pLangid = apVal[iIdx++];
+  if( idxNum & FTS3_HAVE_DOCID_GE ) pDocidGe = apVal[iIdx++];
+  if( idxNum & FTS3_HAVE_DOCID_LE ) pDocidLe = apVal[iIdx++];
+  assert( iIdx==nVal );
+
+  /* In case the cursor has been used before, clear it now. */
+  sqlite3_finalize(pCsr->pStmt);
+  sqlite3_free(pCsr->aDoclist);
+  sqlite3Fts3MIBufferFree(pCsr->pMIBuffer);
+  sqlite3Fts3ExprFree(pCsr->pExpr);
+  memset(&pCursor[1], 0, sizeof(Fts3Cursor)-sizeof(sqlite3_vtab_cursor));
+
+  /* Set the lower and upper bounds on docids to return */
+  pCsr->iMinDocid = fts3DocidRange(pDocidGe, SMALLEST_INT64);
+  pCsr->iMaxDocid = fts3DocidRange(pDocidLe, LARGEST_INT64);
+
+  if( idxStr ){
+    pCsr->bDesc = (idxStr[0]=='D');
+  }else{
+    pCsr->bDesc = p->bDescIdx;
+  }
+  pCsr->eSearch = (i16)eSearch;
+
+  if( eSearch!=FTS3_DOCID_SEARCH && eSearch!=FTS3_FULLSCAN_SEARCH ){
+    int iCol = eSearch-FTS3_FULLTEXT_SEARCH;
+    const char *zQuery = (const char *)sqlite3_value_text(pCons);
+
+    if( zQuery==0 && sqlite3_value_type(pCons)!=SQLITE_NULL ){
+      return SQLITE_NOMEM;
+    }
+
+    pCsr->iLangid = 0;
+    if( pLangid ) pCsr->iLangid = sqlite3_value_int(pLangid);
+
+    assert( p->base.zErrMsg==0 );
+    rc = sqlite3Fts3ExprParse(p->pTokenizer, pCsr->iLangid,
+        p->azColumn, p->bFts4, p->nColumn, iCol, zQuery, -1, &pCsr->pExpr, 
+        &p->base.zErrMsg
+    );
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+
+    rc = fts3EvalStart(pCsr);
+    sqlite3Fts3SegmentsClose(p);
+    if( rc!=SQLITE_OK ) return rc;
+    pCsr->pNextId = pCsr->aDoclist;
+    pCsr->iPrevId = 0;
+  }
+
+  /* Compile a SELECT statement for this cursor. For a full-table-scan, the
+  ** statement loops through all rows of the %_content table. For a
+  ** full-text query or docid lookup, the statement retrieves a single
+  ** row by docid.
+  */
+  if( eSearch==FTS3_FULLSCAN_SEARCH ){
+    if( pDocidGe || pDocidLe ){
+      zSql = sqlite3_mprintf(
+          "SELECT %s WHERE rowid BETWEEN %lld AND %lld ORDER BY rowid %s",
+          p->zReadExprlist, pCsr->iMinDocid, pCsr->iMaxDocid,
+          (pCsr->bDesc ? "DESC" : "ASC")
+      );
+    }else{
+      zSql = sqlite3_mprintf("SELECT %s ORDER BY rowid %s", 
+          p->zReadExprlist, (pCsr->bDesc ? "DESC" : "ASC")
+      );
+    }
+    if( zSql ){
+      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
+      sqlite3_free(zSql);
+    }else{
+      rc = SQLITE_NOMEM;
+    }
+  }else if( eSearch==FTS3_DOCID_SEARCH ){
+    rc = fts3CursorSeekStmt(pCsr, &pCsr->pStmt);
+    if( rc==SQLITE_OK ){
+      rc = sqlite3_bind_value(pCsr->pStmt, 1, pCons);
+    }
+  }
+  if( rc!=SQLITE_OK ) return rc;
+
+  return fts3NextMethod(pCursor);
+}
+
+/* 
+** This is the xEof method of the virtual table. SQLite calls this 
+** routine to find out if it has reached the end of a result set.
+*/
+static int fts3EofMethod(sqlite3_vtab_cursor *pCursor){
+  return ((Fts3Cursor *)pCursor)->isEof;
+}
+
+/* 
+** This is the xRowid method. The SQLite core calls this routine to
+** retrieve the rowid for the current row of the result set. fts3
+** exposes %_content.docid as the rowid for the virtual table. The
+** rowid should be written to *pRowid.
+*/
+static int fts3RowidMethod(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
+  Fts3Cursor *pCsr = (Fts3Cursor *) pCursor;
+  *pRowid = pCsr->iPrevId;
+  return SQLITE_OK;
+}
+
+/* 
+** This is the xColumn method, called by SQLite to request a value from
+** the row that the supplied cursor currently points to.
+**
+** If:
+**
+**   (iCol <  p->nColumn)   -> The value of the iCol'th user column.
+**   (iCol == p->nColumn)   -> Magic column with the same name as the table.
+**   (iCol == p->nColumn+1) -> Docid column
+**   (iCol == p->nColumn+2) -> Langid column
+*/
+static int fts3ColumnMethod(
+  sqlite3_vtab_cursor *pCursor,   /* Cursor to retrieve value from */
+  sqlite3_context *pCtx,          /* Context for sqlite3_result_xxx() calls */
+  int iCol                        /* Index of column to read value from */
+){
+  int rc = SQLITE_OK;             /* Return Code */
+  Fts3Cursor *pCsr = (Fts3Cursor *) pCursor;
+  Fts3Table *p = (Fts3Table *)pCursor->pVtab;
+
+  /* The column value supplied by SQLite must be in range. */
+  assert( iCol>=0 && iCol<=p->nColumn+2 );
+
+  if( iCol==p->nColumn+1 ){
+    /* This call is a request for the "docid" column. Since "docid" is an 
+    ** alias for "rowid", use the xRowid() method to obtain the value.
+    */
+    sqlite3_result_int64(pCtx, pCsr->iPrevId);
+  }else if( iCol==p->nColumn ){
+    /* The extra column whose name is the same as the table.
+    ** Return a blob which is a pointer to the cursor.  */
+    sqlite3_result_blob(pCtx, &pCsr, sizeof(pCsr), SQLITE_TRANSIENT);
+  }else if( iCol==p->nColumn+2 && pCsr->pExpr ){
+    sqlite3_result_int64(pCtx, pCsr->iLangid);
+  }else{
+    /* The requested column is either a user column (one that contains 
+    ** indexed data), or the language-id column.  */
+    rc = fts3CursorSeek(0, pCsr);
+
+    if( rc==SQLITE_OK ){
+      if( iCol==p->nColumn+2 ){
+        int iLangid = 0;
+        if( p->zLanguageid ){
+          iLangid = sqlite3_column_int(pCsr->pStmt, p->nColumn+1);
+        }
+        sqlite3_result_int(pCtx, iLangid);
+      }else if( sqlite3_data_count(pCsr->pStmt)>(iCol+1) ){
+        sqlite3_result_value(pCtx, sqlite3_column_value(pCsr->pStmt, iCol+1));
+      }
+    }
+  }
+
+  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
+  return rc;
+}
+
+/* 
+** This function is the implementation of the xUpdate callback used by 
+** FTS3 virtual tables. It is invoked by SQLite each time a row is to be
+** inserted, updated or deleted.
+*/
+static int fts3UpdateMethod(
+  sqlite3_vtab *pVtab,            /* Virtual table handle */
+  int nArg,                       /* Size of argument array */
+  sqlite3_value **apVal,          /* Array of arguments */
+  sqlite_int64 *pRowid            /* OUT: The affected (or effected) rowid */
+){
+  return sqlite3Fts3UpdateMethod(pVtab, nArg, apVal, pRowid);
+}
+
+/*
+** Implementation of xSync() method. Flush the contents of the pending-terms
+** hash-table to the database.
+*/
+static int fts3SyncMethod(sqlite3_vtab *pVtab){
+
+  /* Following an incremental-merge operation, assuming that the input
+  ** segments are not completely consumed (the usual case), they are updated
+  ** in place to remove the entries that have already been merged. This
+  ** involves updating the leaf block that contains the smallest unmerged
+  ** entry and each block (if any) between the leaf and the root node. So
+  ** if the height of the input segment b-trees is N, and input segments
+  ** are merged eight at a time, updating the input segments at the end
+  ** of an incremental-merge requires writing (8*(1+N)) blocks. N is usually
+  ** small - often between 0 and 2. So the overhead of the incremental
+  ** merge is somewhere between 8 and 24 blocks. To avoid this overhead
+  ** dwarfing the actual productive work accomplished, the incremental merge
+  ** is only attempted if it will write at least 64 leaf blocks. Hence
+  ** nMinMerge.
+  **
+  ** Of course, updating the input segments also involves deleting a bunch
+  ** of blocks from the segments table. But this is not considered overhead
+  ** as it would also be required by a crisis-merge that used the same input 
+  ** segments.
+  */
+  const u32 nMinMerge = 64;       /* Minimum amount of incr-merge work to do */
+
+  Fts3Table *p = (Fts3Table*)pVtab;
+  int rc = sqlite3Fts3PendingTermsFlush(p);
+
+  if( rc==SQLITE_OK 
+   && p->nLeafAdd>(nMinMerge/16) 
+   && p->nAutoincrmerge && p->nAutoincrmerge!=0xff
+  ){
+    int mxLevel = 0;              /* Maximum relative level value in db */
+    int A;                        /* Incr-merge parameter A */
+
+    rc = sqlite3Fts3MaxLevel(p, &mxLevel);
+    assert( rc==SQLITE_OK || mxLevel==0 );
+    A = p->nLeafAdd * mxLevel;
+    A += (A/2);
+    if( A>(int)nMinMerge ) rc = sqlite3Fts3Incrmerge(p, A, p->nAutoincrmerge);
+  }
+  sqlite3Fts3SegmentsClose(p);
+  return rc;
+}
+
+/*
+** If it is currently unknown whether or not the FTS table has an %_stat
+** table (if p->bHasStat==2), attempt to determine this (set p->bHasStat
+** to 0 or 1). Return SQLITE_OK if successful, or an SQLite error code
+** if an error occurs.
+*/
+static int fts3SetHasStat(Fts3Table *p){
+  int rc = SQLITE_OK;
+  if( p->bHasStat==2 ){
+    const char *zFmt ="SELECT 1 FROM %Q.sqlite_master WHERE tbl_name='%q_stat'";
+    char *zSql = sqlite3_mprintf(zFmt, p->zDb, p->zName);
+    if( zSql ){
+      sqlite3_stmt *pStmt = 0;
+      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pStmt, 0);
+      if( rc==SQLITE_OK ){
+        int bHasStat = (sqlite3_step(pStmt)==SQLITE_ROW);
+        rc = sqlite3_finalize(pStmt);
+        if( rc==SQLITE_OK ) p->bHasStat = bHasStat;
+      }
+      sqlite3_free(zSql);
+    }else{
+      rc = SQLITE_NOMEM;
+    }
+  }
+  return rc;
+}
+
+/*
+** Implementation of xBegin() method. 
+*/
+static int fts3BeginMethod(sqlite3_vtab *pVtab){
+  Fts3Table *p = (Fts3Table*)pVtab;
+  UNUSED_PARAMETER(pVtab);
+  assert( p->pSegments==0 );
+  assert( p->nPendingData==0 );
+  assert( p->inTransaction!=1 );
+  TESTONLY( p->inTransaction = 1 );
+  TESTONLY( p->mxSavepoint = -1; );
+  p->nLeafAdd = 0;
+  return fts3SetHasStat(p);
+}
+
+/*
+** Implementation of xCommit() method. This is a no-op. The contents of
+** the pending-terms hash-table have already been flushed into the database
+** by fts3SyncMethod().
+*/
+static int fts3CommitMethod(sqlite3_vtab *pVtab){
+  TESTONLY( Fts3Table *p = (Fts3Table*)pVtab );
+  UNUSED_PARAMETER(pVtab);
+  assert( p->nPendingData==0 );
+  assert( p->inTransaction!=0 );
+  assert( p->pSegments==0 );
+  TESTONLY( p->inTransaction = 0 );
+  TESTONLY( p->mxSavepoint = -1; );
+  return SQLITE_OK;
+}
+
+/*
+** Implementation of xRollback(). Discard the contents of the pending-terms
+** hash-table. Any changes made to the database are reverted by SQLite.
+*/
+static int fts3RollbackMethod(sqlite3_vtab *pVtab){
+  Fts3Table *p = (Fts3Table*)pVtab;
+  sqlite3Fts3PendingTermsClear(p);
+  assert( p->inTransaction!=0 );
+  TESTONLY( p->inTransaction = 0 );
+  TESTONLY( p->mxSavepoint = -1; );
+  return SQLITE_OK;
+}
+
+/*
+** When called, *ppPoslist must point to the byte immediately following the
+** end of a position-list. i.e. ( (*ppPoslist)[-1]==POS_END ). This function
+** moves *ppPoslist so that it instead points to the first byte of the
+** same position list.
+*/
+static void fts3ReversePoslist(char *pStart, char **ppPoslist){
+  char *p = &(*ppPoslist)[-2];
+  char c = 0;
+
+  /* Skip backwards passed any trailing 0x00 bytes added by NearTrim() */
+  while( p>pStart && (c=*p--)==0 );
+
+  /* Search backwards for a varint with value zero (the end of the previous 
+  ** poslist). This is an 0x00 byte preceded by some byte that does not
+  ** have the 0x80 bit set.  */
+  while( p>pStart && (*p & 0x80) | c ){ 
+    c = *p--; 
+  }
+  assert( p==pStart || c==0 );
+
+  /* At this point p points to that preceding byte without the 0x80 bit
+  ** set. So to find the start of the poslist, skip forward 2 bytes then
+  ** over a varint. 
+  **
+  ** Normally. The other case is that p==pStart and the poslist to return
+  ** is the first in the doclist. In this case do not skip forward 2 bytes.
+  ** The second part of the if condition (c==0 && *ppPoslist>&p[2])
+  ** is required for cases where the first byte of a doclist and the
+  ** doclist is empty. For example, if the first docid is 10, a doclist
+  ** that begins with:
+  **
+  **   0x0A 0x00 <next docid delta varint>
+  */
+  if( p>pStart || (c==0 && *ppPoslist>&p[2]) ){ p = &p[2]; }
+  while( *p++&0x80 );
+  *ppPoslist = p;
+}
+
+/*
+** Helper function used by the implementation of the overloaded snippet(),
+** offsets() and optimize() SQL functions.
+**
+** If the value passed as the third argument is a blob of size
+** sizeof(Fts3Cursor*), then the blob contents are copied to the 
+** output variable *ppCsr and SQLITE_OK is returned. Otherwise, an error
+** message is written to context pContext and SQLITE_ERROR returned. The
+** string passed via zFunc is used as part of the error message.
+*/
+static int fts3FunctionArg(
+  sqlite3_context *pContext,      /* SQL function call context */
+  const char *zFunc,              /* Function name */
+  sqlite3_value *pVal,            /* argv[0] passed to function */
+  Fts3Cursor **ppCsr              /* OUT: Store cursor handle here */
+){
+  Fts3Cursor *pRet;
+  if( sqlite3_value_type(pVal)!=SQLITE_BLOB 
+   || sqlite3_value_bytes(pVal)!=sizeof(Fts3Cursor *)
+  ){
+    char *zErr = sqlite3_mprintf("illegal first argument to %s", zFunc);
+    sqlite3_result_error(pContext, zErr, -1);
+    sqlite3_free(zErr);
+    return SQLITE_ERROR;
+  }
+  memcpy(&pRet, sqlite3_value_blob(pVal), sizeof(Fts3Cursor *));
+  *ppCsr = pRet;
+  return SQLITE_OK;
+}
+
+/*
+** Implementation of the snippet() function for FTS3
+*/
+static void fts3SnippetFunc(
+  sqlite3_context *pContext,      /* SQLite function call context */
+  int nVal,                       /* Size of apVal[] array */
+  sqlite3_value **apVal           /* Array of arguments */
+){
+  Fts3Cursor *pCsr;               /* Cursor handle passed through apVal[0] */
+  const char *zStart = "<b>";
+  const char *zEnd = "</b>";
+  const char *zEllipsis = "<b>...</b>";
+  int iCol = -1;
+  int nToken = 15;                /* Default number of tokens in snippet */
+
+  /* There must be at least one argument passed to this function (otherwise
+  ** the non-overloaded version would have been called instead of this one).
+  */
+  assert( nVal>=1 );
+
+  if( nVal>6 ){
+    sqlite3_result_error(pContext, 
+        "wrong number of arguments to function snippet()", -1);
+    return;
+  }
+  if( fts3FunctionArg(pContext, "snippet", apVal[0], &pCsr) ) return;
+
+  switch( nVal ){
+    case 6: nToken = sqlite3_value_int(apVal[5]);
+    case 5: iCol = sqlite3_value_int(apVal[4]);
+    case 4: zEllipsis = (const char*)sqlite3_value_text(apVal[3]);
+    case 3: zEnd = (const char*)sqlite3_value_text(apVal[2]);
+    case 2: zStart = (const char*)sqlite3_value_text(apVal[1]);
+  }
+  if( !zEllipsis || !zEnd || !zStart ){
+    sqlite3_result_error_nomem(pContext);
+  }else if( nToken==0 ){
+    sqlite3_result_text(pContext, "", -1, SQLITE_STATIC);
+  }else if( SQLITE_OK==fts3CursorSeek(pContext, pCsr) ){
+    sqlite3Fts3Snippet(pContext, pCsr, zStart, zEnd, zEllipsis, iCol, nToken);
+  }
+}
+
+/*
+** Implementation of the offsets() function for FTS3
+*/
+static void fts3OffsetsFunc(
+  sqlite3_context *pContext,      /* SQLite function call context */
+  int nVal,                       /* Size of argument array */
+  sqlite3_value **apVal           /* Array of arguments */
+){
+  Fts3Cursor *pCsr;               /* Cursor handle passed through apVal[0] */
+
+  UNUSED_PARAMETER(nVal);
+
+  assert( nVal==1 );
+  if( fts3FunctionArg(pContext, "offsets", apVal[0], &pCsr) ) return;
+  assert( pCsr );
+  if( SQLITE_OK==fts3CursorSeek(pContext, pCsr) ){
+    sqlite3Fts3Offsets(pContext, pCsr);
+  }
+}
+
+/* 
+** Implementation of the special optimize() function for FTS3. This 
+** function merges all segments in the database to a single segment.
+** Example usage is:
+**
+**   SELECT optimize(t) FROM t LIMIT 1;
+**
+** where 't' is the name of an FTS3 table.
+*/
+static void fts3OptimizeFunc(
+  sqlite3_context *pContext,      /* SQLite function call context */
+  int nVal,                       /* Size of argument array */
+  sqlite3_value **apVal           /* Array of arguments */
+){
+  int rc;                         /* Return code */
+  Fts3Table *p;                   /* Virtual table handle */
+  Fts3Cursor *pCursor;            /* Cursor handle passed through apVal[0] */
+
+  UNUSED_PARAMETER(nVal);
+
+  assert( nVal==1 );
+  if( fts3FunctionArg(pContext, "optimize", apVal[0], &pCursor) ) return;
+  p = (Fts3Table *)pCursor->base.pVtab;
+  assert( p );
+
+  rc = sqlite3Fts3Optimize(p);
+
+  switch( rc ){
+    case SQLITE_OK:
+      sqlite3_result_text(pContext, "Index optimized", -1, SQLITE_STATIC);
+      break;
+    case SQLITE_DONE:
+      sqlite3_result_text(pContext, "Index already optimal", -1, SQLITE_STATIC);
+      break;
+    default:
+      sqlite3_result_error_code(pContext, rc);
+      break;
+  }
+}
+
+/*
+** Implementation of the matchinfo() function for FTS3
+*/
+static void fts3MatchinfoFunc(
+  sqlite3_context *pContext,      /* SQLite function call context */
+  int nVal,                       /* Size of argument array */
+  sqlite3_value **apVal           /* Array of arguments */
+){
+  Fts3Cursor *pCsr;               /* Cursor handle passed through apVal[0] */
+  assert( nVal==1 || nVal==2 );
+  if( SQLITE_OK==fts3FunctionArg(pContext, "matchinfo", apVal[0], &pCsr) ){
+    const char *zArg = 0;
+    if( nVal>1 ){
+      zArg = (const char *)sqlite3_value_text(apVal[1]);
+    }
+    sqlite3Fts3Matchinfo(pContext, pCsr, zArg);
+  }
+}
+
+/*
+** This routine implements the xFindFunction method for the FTS3
+** virtual table.
+*/
+static int fts3FindFunctionMethod(
+  sqlite3_vtab *pVtab,            /* Virtual table handle */
+  int nArg,                       /* Number of SQL function arguments */
+  const char *zName,              /* Name of SQL function */
+  void (**pxFunc)(sqlite3_context*,int,sqlite3_value**), /* OUT: Result */
+  void **ppArg                    /* Unused */
+){
+  struct Overloaded {
+    const char *zName;
+    void (*xFunc)(sqlite3_context*,int,sqlite3_value**);
+  } aOverload[] = {
+    { "snippet", fts3SnippetFunc },
+    { "offsets", fts3OffsetsFunc },
+    { "optimize", fts3OptimizeFunc },
+    { "matchinfo", fts3MatchinfoFunc },
+  };
+  int i;                          /* Iterator variable */
+
+  UNUSED_PARAMETER(pVtab);
+  UNUSED_PARAMETER(nArg);
+  UNUSED_PARAMETER(ppArg);
+
+  for(i=0; i<SizeofArray(aOverload); i++){
+    if( strcmp(zName, aOverload[i].zName)==0 ){
+      *pxFunc = aOverload[i].xFunc;
+      return 1;
+    }
+  }
+
+  /* No function of the specified name was found. Return 0. */
+  return 0;
+}
+
+/*
+** Implementation of FTS3 xRename method. Rename an fts3 table.
+*/
+static int fts3RenameMethod(
+  sqlite3_vtab *pVtab,            /* Virtual table handle */
+  const char *zName               /* New name of table */
+){
+  Fts3Table *p = (Fts3Table *)pVtab;
+  sqlite3 *db = p->db;            /* Database connection */
+  int rc;                         /* Return Code */
+
+  /* At this point it must be known if the %_stat table exists or not.
+  ** So bHasStat may not be 2.  */
+  rc = fts3SetHasStat(p);
+  
+  /* As it happens, the pending terms table is always empty here. This is
+  ** because an "ALTER TABLE RENAME TABLE" statement inside a transaction 
+  ** always opens a savepoint transaction. And the xSavepoint() method 
+  ** flushes the pending terms table. But leave the (no-op) call to
+  ** PendingTermsFlush() in in case that changes.
+  */
+  assert( p->nPendingData==0 );
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts3PendingTermsFlush(p);
+  }
+
+  if( p->zContentTbl==0 ){
+    fts3DbExec(&rc, db,
+      "ALTER TABLE %Q.'%q_content'  RENAME TO '%q_content';",
+      p->zDb, p->zName, zName
+    );
+  }
+
+  if( p->bHasDocsize ){
+    fts3DbExec(&rc, db,
+      "ALTER TABLE %Q.'%q_docsize'  RENAME TO '%q_docsize';",
+      p->zDb, p->zName, zName
+    );
+  }
+  if( p->bHasStat ){
+    fts3DbExec(&rc, db,
+      "ALTER TABLE %Q.'%q_stat'  RENAME TO '%q_stat';",
+      p->zDb, p->zName, zName
+    );
+  }
+  fts3DbExec(&rc, db,
+    "ALTER TABLE %Q.'%q_segments' RENAME TO '%q_segments';",
+    p->zDb, p->zName, zName
+  );
+  fts3DbExec(&rc, db,
+    "ALTER TABLE %Q.'%q_segdir'   RENAME TO '%q_segdir';",
+    p->zDb, p->zName, zName
+  );
+  return rc;
+}
+
+/*
+** The xSavepoint() method.
+**
+** Flush the contents of the pending-terms table to disk.
+*/
+static int fts3SavepointMethod(sqlite3_vtab *pVtab, int iSavepoint){
+  int rc = SQLITE_OK;
+  UNUSED_PARAMETER(iSavepoint);
+  assert( ((Fts3Table *)pVtab)->inTransaction );
+  assert( ((Fts3Table *)pVtab)->mxSavepoint < iSavepoint );
+  TESTONLY( ((Fts3Table *)pVtab)->mxSavepoint = iSavepoint );
+  if( ((Fts3Table *)pVtab)->bIgnoreSavepoint==0 ){
+    rc = fts3SyncMethod(pVtab);
+  }
+  return rc;
+}
+
+/*
+** The xRelease() method.
+**
+** This is a no-op.
+*/
+static int fts3ReleaseMethod(sqlite3_vtab *pVtab, int iSavepoint){
+  TESTONLY( Fts3Table *p = (Fts3Table*)pVtab );
+  UNUSED_PARAMETER(iSavepoint);
+  UNUSED_PARAMETER(pVtab);
+  assert( p->inTransaction );
+  assert( p->mxSavepoint >= iSavepoint );
+  TESTONLY( p->mxSavepoint = iSavepoint-1 );
+  return SQLITE_OK;
+}
+
+/*
+** The xRollbackTo() method.
+**
+** Discard the contents of the pending terms table.
+*/
+static int fts3RollbackToMethod(sqlite3_vtab *pVtab, int iSavepoint){
+  Fts3Table *p = (Fts3Table*)pVtab;
+  UNUSED_PARAMETER(iSavepoint);
+  assert( p->inTransaction );
+  assert( p->mxSavepoint >= iSavepoint );
+  TESTONLY( p->mxSavepoint = iSavepoint );
+  sqlite3Fts3PendingTermsClear(p);
+  return SQLITE_OK;
+}
+
+static const sqlite3_module fts3Module = {
+  /* iVersion      */ 2,
+  /* xCreate       */ fts3CreateMethod,
+  /* xConnect      */ fts3ConnectMethod,
+  /* xBestIndex    */ fts3BestIndexMethod,
+  /* xDisconnect   */ fts3DisconnectMethod,
+  /* xDestroy      */ fts3DestroyMethod,
+  /* xOpen         */ fts3OpenMethod,
+  /* xClose        */ fts3CloseMethod,
+  /* xFilter       */ fts3FilterMethod,
+  /* xNext         */ fts3NextMethod,
+  /* xEof          */ fts3EofMethod,
+  /* xColumn       */ fts3ColumnMethod,
+  /* xRowid        */ fts3RowidMethod,
+  /* xUpdate       */ fts3UpdateMethod,
+  /* xBegin        */ fts3BeginMethod,
+  /* xSync         */ fts3SyncMethod,
+  /* xCommit       */ fts3CommitMethod,
+  /* xRollback     */ fts3RollbackMethod,
+  /* xFindFunction */ fts3FindFunctionMethod,
+  /* xRename */       fts3RenameMethod,
+  /* xSavepoint    */ fts3SavepointMethod,
+  /* xRelease      */ fts3ReleaseMethod,
+  /* xRollbackTo   */ fts3RollbackToMethod,
+};
+
+/*
+** This function is registered as the module destructor (called when an
+** FTS3 enabled database connection is closed). It frees the memory
+** allocated for the tokenizer hash table.
+*/
+static void hashDestroy(void *p){
+  Fts3Hash *pHash = (Fts3Hash *)p;
+  sqlite3Fts3HashClear(pHash);
+  sqlite3_free(pHash);
+}
+
+/*
+** The fts3 built-in tokenizers - "simple", "porter" and "icu"- are 
+** implemented in files fts3_tokenizer1.c, fts3_porter.c and fts3_icu.c
+** respectively. The following three forward declarations are for functions
+** declared in these files used to retrieve the respective implementations.
+**
+** Calling sqlite3Fts3SimpleTokenizerModule() sets the value pointed
+** to by the argument to point to the "simple" tokenizer implementation.
+** And so on.
+*/
+SQLITE_PRIVATE void sqlite3Fts3SimpleTokenizerModule(sqlite3_tokenizer_module const**ppModule);
+SQLITE_PRIVATE void sqlite3Fts3PorterTokenizerModule(sqlite3_tokenizer_module const**ppModule);
+#ifndef SQLITE_DISABLE_FTS3_UNICODE
+SQLITE_PRIVATE void sqlite3Fts3UnicodeTokenizer(sqlite3_tokenizer_module const**ppModule);
+#endif
+#ifdef SQLITE_ENABLE_ICU
+SQLITE_PRIVATE void sqlite3Fts3IcuTokenizerModule(sqlite3_tokenizer_module const**ppModule);
+#endif
+
+/*
+** Initialize the fts3 extension. If this extension is built as part
+** of the sqlite library, then this function is called directly by
+** SQLite. If fts3 is built as a dynamically loadable extension, this
+** function is called by the sqlite3_extension_init() entry point.
+*/
+SQLITE_PRIVATE int sqlite3Fts3Init(sqlite3 *db){
+  int rc = SQLITE_OK;
+  Fts3Hash *pHash = 0;
+  const sqlite3_tokenizer_module *pSimple = 0;
+  const sqlite3_tokenizer_module *pPorter = 0;
+#ifndef SQLITE_DISABLE_FTS3_UNICODE
+  const sqlite3_tokenizer_module *pUnicode = 0;
+#endif
+
+#ifdef SQLITE_ENABLE_ICU
+  const sqlite3_tokenizer_module *pIcu = 0;
+  sqlite3Fts3IcuTokenizerModule(&pIcu);
+#endif
+
+#ifndef SQLITE_DISABLE_FTS3_UNICODE
+  sqlite3Fts3UnicodeTokenizer(&pUnicode);
+#endif
+
+#ifdef SQLITE_TEST
+  rc = sqlite3Fts3InitTerm(db);
+  if( rc!=SQLITE_OK ) return rc;
+#endif
+
+  rc = sqlite3Fts3InitAux(db);
+  if( rc!=SQLITE_OK ) return rc;
+
+  sqlite3Fts3SimpleTokenizerModule(&pSimple);
+  sqlite3Fts3PorterTokenizerModule(&pPorter);
+
+  /* Allocate and initialize the hash-table used to store tokenizers. */
+  pHash = sqlite3_malloc(sizeof(Fts3Hash));
+  if( !pHash ){
+    rc = SQLITE_NOMEM;
+  }else{
+    sqlite3Fts3HashInit(pHash, FTS3_HASH_STRING, 1);
+  }
+
+  /* Load the built-in tokenizers into the hash table */
+  if( rc==SQLITE_OK ){
+    if( sqlite3Fts3HashInsert(pHash, "simple", 7, (void *)pSimple)
+     || sqlite3Fts3HashInsert(pHash, "porter", 7, (void *)pPorter) 
+
+#ifndef SQLITE_DISABLE_FTS3_UNICODE
+     || sqlite3Fts3HashInsert(pHash, "unicode61", 10, (void *)pUnicode) 
+#endif
+#ifdef SQLITE_ENABLE_ICU
+     || (pIcu && sqlite3Fts3HashInsert(pHash, "icu", 4, (void *)pIcu))
+#endif
+    ){
+      rc = SQLITE_NOMEM;
+    }
+  }
+
+#ifdef SQLITE_TEST
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts3ExprInitTestInterface(db);
+  }
+#endif
+
+  /* Create the virtual table wrapper around the hash-table and overload 
+  ** the two scalar functions. If this is successful, register the
+  ** module with sqlite.
+  */
+  if( SQLITE_OK==rc 
+   && SQLITE_OK==(rc = sqlite3Fts3InitHashTable(db, pHash, "fts3_tokenizer"))
+   && SQLITE_OK==(rc = sqlite3_overload_function(db, "snippet", -1))
+   && SQLITE_OK==(rc = sqlite3_overload_function(db, "offsets", 1))
+   && SQLITE_OK==(rc = sqlite3_overload_function(db, "matchinfo", 1))
+   && SQLITE_OK==(rc = sqlite3_overload_function(db, "matchinfo", 2))
+   && SQLITE_OK==(rc = sqlite3_overload_function(db, "optimize", 1))
+  ){
+    rc = sqlite3_create_module_v2(
+        db, "fts3", &fts3Module, (void *)pHash, hashDestroy
+    );
+    if( rc==SQLITE_OK ){
+      rc = sqlite3_create_module_v2(
+          db, "fts4", &fts3Module, (void *)pHash, 0
+      );
+    }
+    if( rc==SQLITE_OK ){
+      rc = sqlite3Fts3InitTok(db, (void *)pHash);
+    }
+    return rc;
+  }
+
+
+  /* An error has occurred. Delete the hash table and return the error code. */
+  assert( rc!=SQLITE_OK );
+  if( pHash ){
+    sqlite3Fts3HashClear(pHash);
+    sqlite3_free(pHash);
+  }
+  return rc;
+}
+
+/*
+** Allocate an Fts3MultiSegReader for each token in the expression headed
+** by pExpr. 
+**
+** An Fts3SegReader object is a cursor that can seek or scan a range of
+** entries within a single segment b-tree. An Fts3MultiSegReader uses multiple
+** Fts3SegReader objects internally to provide an interface to seek or scan
+** within the union of all segments of a b-tree. Hence the name.
+**
+** If the allocated Fts3MultiSegReader just seeks to a single entry in a
+** segment b-tree (if the term is not a prefix or it is a prefix for which
+** there exists prefix b-tree of the right length) then it may be traversed
+** and merged incrementally. Otherwise, it has to be merged into an in-memory 
+** doclist and then traversed.
+*/
+static void fts3EvalAllocateReaders(
+  Fts3Cursor *pCsr,               /* FTS cursor handle */
+  Fts3Expr *pExpr,                /* Allocate readers for this expression */
+  int *pnToken,                   /* OUT: Total number of tokens in phrase. */
+  int *pnOr,                      /* OUT: Total number of OR nodes in expr. */
+  int *pRc                        /* IN/OUT: Error code */
+){
+  if( pExpr && SQLITE_OK==*pRc ){
+    if( pExpr->eType==FTSQUERY_PHRASE ){
+      int i;
+      int nToken = pExpr->pPhrase->nToken;
+      *pnToken += nToken;
+      for(i=0; i<nToken; i++){
+        Fts3PhraseToken *pToken = &pExpr->pPhrase->aToken[i];
+        int rc = fts3TermSegReaderCursor(pCsr, 
+            pToken->z, pToken->n, pToken->isPrefix, &pToken->pSegcsr
+        );
+        if( rc!=SQLITE_OK ){
+          *pRc = rc;
+          return;
+        }
+      }
+      assert( pExpr->pPhrase->iDoclistToken==0 );
+      pExpr->pPhrase->iDoclistToken = -1;
+    }else{
+      *pnOr += (pExpr->eType==FTSQUERY_OR);
+      fts3EvalAllocateReaders(pCsr, pExpr->pLeft, pnToken, pnOr, pRc);
+      fts3EvalAllocateReaders(pCsr, pExpr->pRight, pnToken, pnOr, pRc);
+    }
+  }
+}
+
+/*
+** Arguments pList/nList contain the doclist for token iToken of phrase p.
+** It is merged into the main doclist stored in p->doclist.aAll/nAll.
+**
+** This function assumes that pList points to a buffer allocated using
+** sqlite3_malloc(). This function takes responsibility for eventually
+** freeing the buffer.
+**
+** SQLITE_OK is returned if successful, or SQLITE_NOMEM if an error occurs.
+*/
+static int fts3EvalPhraseMergeToken(
+  Fts3Table *pTab,                /* FTS Table pointer */
+  Fts3Phrase *p,                  /* Phrase to merge pList/nList into */
+  int iToken,                     /* Token pList/nList corresponds to */
+  char *pList,                    /* Pointer to doclist */
+  int nList                       /* Number of bytes in pList */
+){
+  int rc = SQLITE_OK;
+  assert( iToken!=p->iDoclistToken );
+
+  if( pList==0 ){
+    sqlite3_free(p->doclist.aAll);
+    p->doclist.aAll = 0;
+    p->doclist.nAll = 0;
+  }
+
+  else if( p->iDoclistToken<0 ){
+    p->doclist.aAll = pList;
+    p->doclist.nAll = nList;
+  }
+
+  else if( p->doclist.aAll==0 ){
+    sqlite3_free(pList);
+  }
+
+  else {
+    char *pLeft;
+    char *pRight;
+    int nLeft;
+    int nRight;
+    int nDiff;
+
+    if( p->iDoclistToken<iToken ){
+      pLeft = p->doclist.aAll;
+      nLeft = p->doclist.nAll;
+      pRight = pList;
+      nRight = nList;
+      nDiff = iToken - p->iDoclistToken;
+    }else{
+      pRight = p->doclist.aAll;
+      nRight = p->doclist.nAll;
+      pLeft = pList;
+      nLeft = nList;
+      nDiff = p->iDoclistToken - iToken;
+    }
+
+    rc = fts3DoclistPhraseMerge(
+        pTab->bDescIdx, nDiff, pLeft, nLeft, &pRight, &nRight
+    );
+    sqlite3_free(pLeft);
+    p->doclist.aAll = pRight;
+    p->doclist.nAll = nRight;
+  }
+
+  if( iToken>p->iDoclistToken ) p->iDoclistToken = iToken;
+  return rc;
+}
+
+/*
+** Load the doclist for phrase p into p->doclist.aAll/nAll. The loaded doclist
+** does not take deferred tokens into account.
+**
+** SQLITE_OK is returned if no error occurs, otherwise an SQLite error code.
+*/
+static int fts3EvalPhraseLoad(
+  Fts3Cursor *pCsr,               /* FTS Cursor handle */
+  Fts3Phrase *p                   /* Phrase object */
+){
+  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
+  int iToken;
+  int rc = SQLITE_OK;
+
+  for(iToken=0; rc==SQLITE_OK && iToken<p->nToken; iToken++){
+    Fts3PhraseToken *pToken = &p->aToken[iToken];
+    assert( pToken->pDeferred==0 || pToken->pSegcsr==0 );
+
+    if( pToken->pSegcsr ){
+      int nThis = 0;
+      char *pThis = 0;
+      rc = fts3TermSelect(pTab, pToken, p->iColumn, &nThis, &pThis);
+      if( rc==SQLITE_OK ){
+        rc = fts3EvalPhraseMergeToken(pTab, p, iToken, pThis, nThis);
+      }
+    }
+    assert( pToken->pSegcsr==0 );
+  }
+
+  return rc;
+}
+
+/*
+** This function is called on each phrase after the position lists for
+** any deferred tokens have been loaded into memory. It updates the phrases
+** current position list to include only those positions that are really
+** instances of the phrase (after considering deferred tokens). If this
+** means that the phrase does not appear in the current row, doclist.pList
+** and doclist.nList are both zeroed.
+**
+** SQLITE_OK is returned if no error occurs, otherwise an SQLite error code.
+*/
+static int fts3EvalDeferredPhrase(Fts3Cursor *pCsr, Fts3Phrase *pPhrase){
+  int iToken;                     /* Used to iterate through phrase tokens */
+  char *aPoslist = 0;             /* Position list for deferred tokens */
+  int nPoslist = 0;               /* Number of bytes in aPoslist */
+  int iPrev = -1;                 /* Token number of previous deferred token */
+
+  assert( pPhrase->doclist.bFreeList==0 );
+
+  for(iToken=0; iToken<pPhrase->nToken; iToken++){
+    Fts3PhraseToken *pToken = &pPhrase->aToken[iToken];
+    Fts3DeferredToken *pDeferred = pToken->pDeferred;
+
+    if( pDeferred ){
+      char *pList;
+      int nList;
+      int rc = sqlite3Fts3DeferredTokenList(pDeferred, &pList, &nList);
+      if( rc!=SQLITE_OK ) return rc;
+
+      if( pList==0 ){
+        sqlite3_free(aPoslist);
+        pPhrase->doclist.pList = 0;
+        pPhrase->doclist.nList = 0;
+        return SQLITE_OK;
+
+      }else if( aPoslist==0 ){
+        aPoslist = pList;
+        nPoslist = nList;
+
+      }else{
+        char *aOut = pList;
+        char *p1 = aPoslist;
+        char *p2 = aOut;
+
+        assert( iPrev>=0 );
+        fts3PoslistPhraseMerge(&aOut, iToken-iPrev, 0, 1, &p1, &p2);
+        sqlite3_free(aPoslist);
+        aPoslist = pList;
+        nPoslist = (int)(aOut - aPoslist);
+        if( nPoslist==0 ){
+          sqlite3_free(aPoslist);
+          pPhrase->doclist.pList = 0;
+          pPhrase->doclist.nList = 0;
+          return SQLITE_OK;
+        }
+      }
+      iPrev = iToken;
+    }
+  }
+
+  if( iPrev>=0 ){
+    int nMaxUndeferred = pPhrase->iDoclistToken;
+    if( nMaxUndeferred<0 ){
+      pPhrase->doclist.pList = aPoslist;
+      pPhrase->doclist.nList = nPoslist;
+      pPhrase->doclist.iDocid = pCsr->iPrevId;
+      pPhrase->doclist.bFreeList = 1;
+    }else{
+      int nDistance;
+      char *p1;
+      char *p2;
+      char *aOut;
+
+      if( nMaxUndeferred>iPrev ){
+        p1 = aPoslist;
+        p2 = pPhrase->doclist.pList;
+        nDistance = nMaxUndeferred - iPrev;
+      }else{
+        p1 = pPhrase->doclist.pList;
+        p2 = aPoslist;
+        nDistance = iPrev - nMaxUndeferred;
+      }
+
+      aOut = (char *)sqlite3_malloc(nPoslist+8);
+      if( !aOut ){
+        sqlite3_free(aPoslist);
+        return SQLITE_NOMEM;
+      }
+      
+      pPhrase->doclist.pList = aOut;
+      if( fts3PoslistPhraseMerge(&aOut, nDistance, 0, 1, &p1, &p2) ){
+        pPhrase->doclist.bFreeList = 1;
+        pPhrase->doclist.nList = (int)(aOut - pPhrase->doclist.pList);
+      }else{
+        sqlite3_free(aOut);
+        pPhrase->doclist.pList = 0;
+        pPhrase->doclist.nList = 0;
+      }
+      sqlite3_free(aPoslist);
+    }
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Maximum number of tokens a phrase may have to be considered for the
+** incremental doclists strategy.
+*/
+#define MAX_INCR_PHRASE_TOKENS 4
+
+/*
+** This function is called for each Fts3Phrase in a full-text query 
+** expression to initialize the mechanism for returning rows. Once this
+** function has been called successfully on an Fts3Phrase, it may be
+** used with fts3EvalPhraseNext() to iterate through the matching docids.
+**
+** If parameter bOptOk is true, then the phrase may (or may not) use the
+** incremental loading strategy. Otherwise, the entire doclist is loaded into
+** memory within this call.
+**
+** SQLITE_OK is returned if no error occurs, otherwise an SQLite error code.
+*/
+static int fts3EvalPhraseStart(Fts3Cursor *pCsr, int bOptOk, Fts3Phrase *p){
+  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
+  int rc = SQLITE_OK;             /* Error code */
+  int i;
+
+  /* Determine if doclists may be loaded from disk incrementally. This is
+  ** possible if the bOptOk argument is true, the FTS doclists will be
+  ** scanned in forward order, and the phrase consists of 
+  ** MAX_INCR_PHRASE_TOKENS or fewer tokens, none of which are are "^first"
+  ** tokens or prefix tokens that cannot use a prefix-index.  */
+  int bHaveIncr = 0;
+  int bIncrOk = (bOptOk 
+   && pCsr->bDesc==pTab->bDescIdx 
+   && p->nToken<=MAX_INCR_PHRASE_TOKENS && p->nToken>0
+#ifdef SQLITE_TEST
+   && pTab->bNoIncrDoclist==0
+#endif
+  );
+  for(i=0; bIncrOk==1 && i<p->nToken; i++){
+    Fts3PhraseToken *pToken = &p->aToken[i];
+    if( pToken->bFirst || (pToken->pSegcsr!=0 && !pToken->pSegcsr->bLookup) ){
+      bIncrOk = 0;
+    }
+    if( pToken->pSegcsr ) bHaveIncr = 1;
+  }
+
+  if( bIncrOk && bHaveIncr ){
+    /* Use the incremental approach. */
+    int iCol = (p->iColumn >= pTab->nColumn ? -1 : p->iColumn);
+    for(i=0; rc==SQLITE_OK && i<p->nToken; i++){
+      Fts3PhraseToken *pToken = &p->aToken[i];
+      Fts3MultiSegReader *pSegcsr = pToken->pSegcsr;
+      if( pSegcsr ){
+        rc = sqlite3Fts3MsrIncrStart(pTab, pSegcsr, iCol, pToken->z, pToken->n);
+      }
+    }
+    p->bIncr = 1;
+  }else{
+    /* Load the full doclist for the phrase into memory. */
+    rc = fts3EvalPhraseLoad(pCsr, p);
+    p->bIncr = 0;
+  }
+
+  assert( rc!=SQLITE_OK || p->nToken<1 || p->aToken[0].pSegcsr==0 || p->bIncr );
+  return rc;
+}
+
+/*
+** This function is used to iterate backwards (from the end to start) 
+** through doclists. It is used by this module to iterate through phrase
+** doclists in reverse and by the fts3_write.c module to iterate through
+** pending-terms lists when writing to databases with "order=desc".
+**
+** The doclist may be sorted in ascending (parameter bDescIdx==0) or 
+** descending (parameter bDescIdx==1) order of docid. Regardless, this
+** function iterates from the end of the doclist to the beginning.
+*/
+SQLITE_PRIVATE void sqlite3Fts3DoclistPrev(
+  int bDescIdx,                   /* True if the doclist is desc */
+  char *aDoclist,                 /* Pointer to entire doclist */
+  int nDoclist,                   /* Length of aDoclist in bytes */
+  char **ppIter,                  /* IN/OUT: Iterator pointer */
+  sqlite3_int64 *piDocid,         /* IN/OUT: Docid pointer */
+  int *pnList,                    /* OUT: List length pointer */
+  u8 *pbEof                       /* OUT: End-of-file flag */
+){
+  char *p = *ppIter;
+
+  assert( nDoclist>0 );
+  assert( *pbEof==0 );
+  assert( p || *piDocid==0 );
+  assert( !p || (p>aDoclist && p<&aDoclist[nDoclist]) );
+
+  if( p==0 ){
+    sqlite3_int64 iDocid = 0;
+    char *pNext = 0;
+    char *pDocid = aDoclist;
+    char *pEnd = &aDoclist[nDoclist];
+    int iMul = 1;
+
+    while( pDocid<pEnd ){
+      sqlite3_int64 iDelta;
+      pDocid += sqlite3Fts3GetVarint(pDocid, &iDelta);
+      iDocid += (iMul * iDelta);
+      pNext = pDocid;
+      fts3PoslistCopy(0, &pDocid);
+      while( pDocid<pEnd && *pDocid==0 ) pDocid++;
+      iMul = (bDescIdx ? -1 : 1);
+    }
+
+    *pnList = (int)(pEnd - pNext);
+    *ppIter = pNext;
+    *piDocid = iDocid;
+  }else{
+    int iMul = (bDescIdx ? -1 : 1);
+    sqlite3_int64 iDelta;
+    fts3GetReverseVarint(&p, aDoclist, &iDelta);
+    *piDocid -= (iMul * iDelta);
+
+    if( p==aDoclist ){
+      *pbEof = 1;
+    }else{
+      char *pSave = p;
+      fts3ReversePoslist(aDoclist, &p);
+      *pnList = (int)(pSave - p);
+    }
+    *ppIter = p;
+  }
+}
+
+/*
+** Iterate forwards through a doclist.
+*/
+SQLITE_PRIVATE void sqlite3Fts3DoclistNext(
+  int bDescIdx,                   /* True if the doclist is desc */
+  char *aDoclist,                 /* Pointer to entire doclist */
+  int nDoclist,                   /* Length of aDoclist in bytes */
+  char **ppIter,                  /* IN/OUT: Iterator pointer */
+  sqlite3_int64 *piDocid,         /* IN/OUT: Docid pointer */
+  u8 *pbEof                       /* OUT: End-of-file flag */
+){
+  char *p = *ppIter;
+
+  assert( nDoclist>0 );
+  assert( *pbEof==0 );
+  assert( p || *piDocid==0 );
+  assert( !p || (p>=aDoclist && p<=&aDoclist[nDoclist]) );
+
+  if( p==0 ){
+    p = aDoclist;
+    p += sqlite3Fts3GetVarint(p, piDocid);
+  }else{
+    fts3PoslistCopy(0, &p);
+    while( p<&aDoclist[nDoclist] && *p==0 ) p++; 
+    if( p>=&aDoclist[nDoclist] ){
+      *pbEof = 1;
+    }else{
+      sqlite3_int64 iVar;
+      p += sqlite3Fts3GetVarint(p, &iVar);
+      *piDocid += ((bDescIdx ? -1 : 1) * iVar);
+    }
+  }
+
+  *ppIter = p;
+}
+
+/*
+** Advance the iterator pDL to the next entry in pDL->aAll/nAll. Set *pbEof
+** to true if EOF is reached.
+*/
+static void fts3EvalDlPhraseNext(
+  Fts3Table *pTab,
+  Fts3Doclist *pDL,
+  u8 *pbEof
+){
+  char *pIter;                            /* Used to iterate through aAll */
+  char *pEnd = &pDL->aAll[pDL->nAll];     /* 1 byte past end of aAll */
+ 
+  if( pDL->pNextDocid ){
+    pIter = pDL->pNextDocid;
+  }else{
+    pIter = pDL->aAll;
+  }
+
+  if( pIter>=pEnd ){
+    /* We have already reached the end of this doclist. EOF. */
+    *pbEof = 1;
+  }else{
+    sqlite3_int64 iDelta;
+    pIter += sqlite3Fts3GetVarint(pIter, &iDelta);
+    if( pTab->bDescIdx==0 || pDL->pNextDocid==0 ){
+      pDL->iDocid += iDelta;
+    }else{
+      pDL->iDocid -= iDelta;
+    }
+    pDL->pList = pIter;
+    fts3PoslistCopy(0, &pIter);
+    pDL->nList = (int)(pIter - pDL->pList);
+
+    /* pIter now points just past the 0x00 that terminates the position-
+    ** list for document pDL->iDocid. However, if this position-list was
+    ** edited in place by fts3EvalNearTrim(), then pIter may not actually
+    ** point to the start of the next docid value. The following line deals
+    ** with this case by advancing pIter past the zero-padding added by
+    ** fts3EvalNearTrim().  */
+    while( pIter<pEnd && *pIter==0 ) pIter++;
+
+    pDL->pNextDocid = pIter;
+    assert( pIter>=&pDL->aAll[pDL->nAll] || *pIter );
+    *pbEof = 0;
+  }
+}
+
+/*
+** Helper type used by fts3EvalIncrPhraseNext() and incrPhraseTokenNext().
+*/
+typedef struct TokenDoclist TokenDoclist;
+struct TokenDoclist {
+  int bIgnore;
+  sqlite3_int64 iDocid;
+  char *pList;
+  int nList;
+};
+
+/*
+** Token pToken is an incrementally loaded token that is part of a 
+** multi-token phrase. Advance it to the next matching document in the
+** database and populate output variable *p with the details of the new
+** entry. Or, if the iterator has reached EOF, set *pbEof to true.
+**
+** If an error occurs, return an SQLite error code. Otherwise, return 
+** SQLITE_OK.
+*/
+static int incrPhraseTokenNext(
+  Fts3Table *pTab,                /* Virtual table handle */
+  Fts3Phrase *pPhrase,            /* Phrase to advance token of */
+  int iToken,                     /* Specific token to advance */
+  TokenDoclist *p,                /* OUT: Docid and doclist for new entry */
+  u8 *pbEof                       /* OUT: True if iterator is at EOF */
+){
+  int rc = SQLITE_OK;
+
+  if( pPhrase->iDoclistToken==iToken ){
+    assert( p->bIgnore==0 );
+    assert( pPhrase->aToken[iToken].pSegcsr==0 );
+    fts3EvalDlPhraseNext(pTab, &pPhrase->doclist, pbEof);
+    p->pList = pPhrase->doclist.pList;
+    p->nList = pPhrase->doclist.nList;
+    p->iDocid = pPhrase->doclist.iDocid;
+  }else{
+    Fts3PhraseToken *pToken = &pPhrase->aToken[iToken];
+    assert( pToken->pDeferred==0 );
+    assert( pToken->pSegcsr || pPhrase->iDoclistToken>=0 );
+    if( pToken->pSegcsr ){
+      assert( p->bIgnore==0 );
+      rc = sqlite3Fts3MsrIncrNext(
+          pTab, pToken->pSegcsr, &p->iDocid, &p->pList, &p->nList
+      );
+      if( p->pList==0 ) *pbEof = 1;
+    }else{
+      p->bIgnore = 1;
+    }
+  }
+
+  return rc;
+}
+
+
+/*
+** The phrase iterator passed as the second argument:
+**
+**   * features at least one token that uses an incremental doclist, and 
+**
+**   * does not contain any deferred tokens.
+**
+** Advance it to the next matching documnent in the database and populate
+** the Fts3Doclist.pList and nList fields. 
+**
+** If there is no "next" entry and no error occurs, then *pbEof is set to
+** 1 before returning. Otherwise, if no error occurs and the iterator is
+** successfully advanced, *pbEof is set to 0.
+**
+** If an error occurs, return an SQLite error code. Otherwise, return 
+** SQLITE_OK.
+*/
+static int fts3EvalIncrPhraseNext(
+  Fts3Cursor *pCsr,               /* FTS Cursor handle */
+  Fts3Phrase *p,                  /* Phrase object to advance to next docid */
+  u8 *pbEof                       /* OUT: Set to 1 if EOF */
+){
+  int rc = SQLITE_OK;
+  Fts3Doclist *pDL = &p->doclist;
+  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
+  u8 bEof = 0;
+
+  /* This is only called if it is guaranteed that the phrase has at least
+  ** one incremental token. In which case the bIncr flag is set. */
+  assert( p->bIncr==1 );
+
+  if( p->nToken==1 && p->bIncr ){
+    rc = sqlite3Fts3MsrIncrNext(pTab, p->aToken[0].pSegcsr, 
+        &pDL->iDocid, &pDL->pList, &pDL->nList
+    );
+    if( pDL->pList==0 ) bEof = 1;
+  }else{
+    int bDescDoclist = pCsr->bDesc;
+    struct TokenDoclist a[MAX_INCR_PHRASE_TOKENS];
+
+    memset(a, 0, sizeof(a));
+    assert( p->nToken<=MAX_INCR_PHRASE_TOKENS );
+    assert( p->iDoclistToken<MAX_INCR_PHRASE_TOKENS );
+
+    while( bEof==0 ){
+      int bMaxSet = 0;
+      sqlite3_int64 iMax = 0;     /* Largest docid for all iterators */
+      int i;                      /* Used to iterate through tokens */
+
+      /* Advance the iterator for each token in the phrase once. */
+      for(i=0; rc==SQLITE_OK && i<p->nToken && bEof==0; i++){
+        rc = incrPhraseTokenNext(pTab, p, i, &a[i], &bEof);
+        if( a[i].bIgnore==0 && (bMaxSet==0 || DOCID_CMP(iMax, a[i].iDocid)<0) ){
+          iMax = a[i].iDocid;
+          bMaxSet = 1;
+        }
+      }
+      assert( rc!=SQLITE_OK || (p->nToken>=1 && a[p->nToken-1].bIgnore==0) );
+      assert( rc!=SQLITE_OK || bMaxSet );
+
+      /* Keep advancing iterators until they all point to the same document */
+      for(i=0; i<p->nToken; i++){
+        while( rc==SQLITE_OK && bEof==0 
+            && a[i].bIgnore==0 && DOCID_CMP(a[i].iDocid, iMax)<0 
+        ){
+          rc = incrPhraseTokenNext(pTab, p, i, &a[i], &bEof);
+          if( DOCID_CMP(a[i].iDocid, iMax)>0 ){
+            iMax = a[i].iDocid;
+            i = 0;
+          }
+        }
+      }
+
+      /* Check if the current entries really are a phrase match */
+      if( bEof==0 ){
+        int nList = 0;
+        int nByte = a[p->nToken-1].nList;
+        char *aDoclist = sqlite3_malloc(nByte+1);
+        if( !aDoclist ) return SQLITE_NOMEM;
+        memcpy(aDoclist, a[p->nToken-1].pList, nByte+1);
+
+        for(i=0; i<(p->nToken-1); i++){
+          if( a[i].bIgnore==0 ){
+            char *pL = a[i].pList;
+            char *pR = aDoclist;
+            char *pOut = aDoclist;
+            int nDist = p->nToken-1-i;
+            int res = fts3PoslistPhraseMerge(&pOut, nDist, 0, 1, &pL, &pR);
+            if( res==0 ) break;
+            nList = (int)(pOut - aDoclist);
+          }
+        }
+        if( i==(p->nToken-1) ){
+          pDL->iDocid = iMax;
+          pDL->pList = aDoclist;
+          pDL->nList = nList;
+          pDL->bFreeList = 1;
+          break;
+        }
+        sqlite3_free(aDoclist);
+      }
+    }
+  }
+
+  *pbEof = bEof;
+  return rc;
+}
+
+/*
+** Attempt to move the phrase iterator to point to the next matching docid. 
+** If an error occurs, return an SQLite error code. Otherwise, return 
+** SQLITE_OK.
+**
+** If there is no "next" entry and no error occurs, then *pbEof is set to
+** 1 before returning. Otherwise, if no error occurs and the iterator is
+** successfully advanced, *pbEof is set to 0.
+*/
+static int fts3EvalPhraseNext(
+  Fts3Cursor *pCsr,               /* FTS Cursor handle */
+  Fts3Phrase *p,                  /* Phrase object to advance to next docid */
+  u8 *pbEof                       /* OUT: Set to 1 if EOF */
+){
+  int rc = SQLITE_OK;
+  Fts3Doclist *pDL = &p->doclist;
+  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
+
+  if( p->bIncr ){
+    rc = fts3EvalIncrPhraseNext(pCsr, p, pbEof);
+  }else if( pCsr->bDesc!=pTab->bDescIdx && pDL->nAll ){
+    sqlite3Fts3DoclistPrev(pTab->bDescIdx, pDL->aAll, pDL->nAll, 
+        &pDL->pNextDocid, &pDL->iDocid, &pDL->nList, pbEof
+    );
+    pDL->pList = pDL->pNextDocid;
+  }else{
+    fts3EvalDlPhraseNext(pTab, pDL, pbEof);
+  }
+
+  return rc;
+}
+
+/*
+**
+** If *pRc is not SQLITE_OK when this function is called, it is a no-op.
+** Otherwise, fts3EvalPhraseStart() is called on all phrases within the
+** expression. Also the Fts3Expr.bDeferred variable is set to true for any
+** expressions for which all descendent tokens are deferred.
+**
+** If parameter bOptOk is zero, then it is guaranteed that the
+** Fts3Phrase.doclist.aAll/nAll variables contain the entire doclist for
+** each phrase in the expression (subject to deferred token processing).
+** Or, if bOptOk is non-zero, then one or more tokens within the expression
+** may be loaded incrementally, meaning doclist.aAll/nAll is not available.
+**
+** If an error occurs within this function, *pRc is set to an SQLite error
+** code before returning.
+*/
+static void fts3EvalStartReaders(
+  Fts3Cursor *pCsr,               /* FTS Cursor handle */
+  Fts3Expr *pExpr,                /* Expression to initialize phrases in */
+  int *pRc                        /* IN/OUT: Error code */
+){
+  if( pExpr && SQLITE_OK==*pRc ){
+    if( pExpr->eType==FTSQUERY_PHRASE ){
+      int nToken = pExpr->pPhrase->nToken;
+      if( nToken ){
+        int i;
+        for(i=0; i<nToken; i++){
+          if( pExpr->pPhrase->aToken[i].pDeferred==0 ) break;
+        }
+        pExpr->bDeferred = (i==nToken);
+      }
+      *pRc = fts3EvalPhraseStart(pCsr, 1, pExpr->pPhrase);
+    }else{
+      fts3EvalStartReaders(pCsr, pExpr->pLeft, pRc);
+      fts3EvalStartReaders(pCsr, pExpr->pRight, pRc);
+      pExpr->bDeferred = (pExpr->pLeft->bDeferred && pExpr->pRight->bDeferred);
+    }
+  }
+}
+
+/*
+** An array of the following structures is assembled as part of the process
+** of selecting tokens to defer before the query starts executing (as part
+** of the xFilter() method). There is one element in the array for each
+** token in the FTS expression.
+**
+** Tokens are divided into AND/NEAR clusters. All tokens in a cluster belong
+** to phrases that are connected only by AND and NEAR operators (not OR or
+** NOT). When determining tokens to defer, each AND/NEAR cluster is considered
+** separately. The root of a tokens AND/NEAR cluster is stored in 
+** Fts3TokenAndCost.pRoot.
+*/
+typedef struct Fts3TokenAndCost Fts3TokenAndCost;
+struct Fts3TokenAndCost {
+  Fts3Phrase *pPhrase;            /* The phrase the token belongs to */
+  int iToken;                     /* Position of token in phrase */
+  Fts3PhraseToken *pToken;        /* The token itself */
+  Fts3Expr *pRoot;                /* Root of NEAR/AND cluster */
+  int nOvfl;                      /* Number of overflow pages to load doclist */
+  int iCol;                       /* The column the token must match */
+};
+
+/*
+** This function is used to populate an allocated Fts3TokenAndCost array.
+**
+** If *pRc is not SQLITE_OK when this function is called, it is a no-op.
+** Otherwise, if an error occurs during execution, *pRc is set to an
+** SQLite error code.
+*/
+static void fts3EvalTokenCosts(
+  Fts3Cursor *pCsr,               /* FTS Cursor handle */
+  Fts3Expr *pRoot,                /* Root of current AND/NEAR cluster */
+  Fts3Expr *pExpr,                /* Expression to consider */
+  Fts3TokenAndCost **ppTC,        /* Write new entries to *(*ppTC)++ */
+  Fts3Expr ***ppOr,               /* Write new OR root to *(*ppOr)++ */
+  int *pRc                        /* IN/OUT: Error code */
+){
+  if( *pRc==SQLITE_OK ){
+    if( pExpr->eType==FTSQUERY_PHRASE ){
+      Fts3Phrase *pPhrase = pExpr->pPhrase;
+      int i;
+      for(i=0; *pRc==SQLITE_OK && i<pPhrase->nToken; i++){
+        Fts3TokenAndCost *pTC = (*ppTC)++;
+        pTC->pPhrase = pPhrase;
+        pTC->iToken = i;
+        pTC->pRoot = pRoot;
+        pTC->pToken = &pPhrase->aToken[i];
+        pTC->iCol = pPhrase->iColumn;
+        *pRc = sqlite3Fts3MsrOvfl(pCsr, pTC->pToken->pSegcsr, &pTC->nOvfl);
+      }
+    }else if( pExpr->eType!=FTSQUERY_NOT ){
+      assert( pExpr->eType==FTSQUERY_OR
+           || pExpr->eType==FTSQUERY_AND
+           || pExpr->eType==FTSQUERY_NEAR
+      );
+      assert( pExpr->pLeft && pExpr->pRight );
+      if( pExpr->eType==FTSQUERY_OR ){
+        pRoot = pExpr->pLeft;
+        **ppOr = pRoot;
+        (*ppOr)++;
+      }
+      fts3EvalTokenCosts(pCsr, pRoot, pExpr->pLeft, ppTC, ppOr, pRc);
+      if( pExpr->eType==FTSQUERY_OR ){
+        pRoot = pExpr->pRight;
+        **ppOr = pRoot;
+        (*ppOr)++;
+      }
+      fts3EvalTokenCosts(pCsr, pRoot, pExpr->pRight, ppTC, ppOr, pRc);
+    }
+  }
+}
+
+/*
+** Determine the average document (row) size in pages. If successful,
+** write this value to *pnPage and return SQLITE_OK. Otherwise, return
+** an SQLite error code.
+**
+** The average document size in pages is calculated by first calculating 
+** determining the average size in bytes, B. If B is less than the amount
+** of data that will fit on a single leaf page of an intkey table in
+** this database, then the average docsize is 1. Otherwise, it is 1 plus
+** the number of overflow pages consumed by a record B bytes in size.
+*/
+static int fts3EvalAverageDocsize(Fts3Cursor *pCsr, int *pnPage){
+  if( pCsr->nRowAvg==0 ){
+    /* The average document size, which is required to calculate the cost
+    ** of each doclist, has not yet been determined. Read the required 
+    ** data from the %_stat table to calculate it.
+    **
+    ** Entry 0 of the %_stat table is a blob containing (nCol+1) FTS3 
+    ** varints, where nCol is the number of columns in the FTS3 table.
+    ** The first varint is the number of documents currently stored in
+    ** the table. The following nCol varints contain the total amount of
+    ** data stored in all rows of each column of the table, from left
+    ** to right.
+    */
+    int rc;
+    Fts3Table *p = (Fts3Table*)pCsr->base.pVtab;
+    sqlite3_stmt *pStmt;
+    sqlite3_int64 nDoc = 0;
+    sqlite3_int64 nByte = 0;
+    const char *pEnd;
+    const char *a;
+
+    rc = sqlite3Fts3SelectDoctotal(p, &pStmt);
+    if( rc!=SQLITE_OK ) return rc;
+    a = sqlite3_column_blob(pStmt, 0);
+    assert( a );
+
+    pEnd = &a[sqlite3_column_bytes(pStmt, 0)];
+    a += sqlite3Fts3GetVarint(a, &nDoc);
+    while( a<pEnd ){
+      a += sqlite3Fts3GetVarint(a, &nByte);
+    }
+    if( nDoc==0 || nByte==0 ){
+      sqlite3_reset(pStmt);
+      return FTS_CORRUPT_VTAB;
+    }
+
+    pCsr->nDoc = nDoc;
+    pCsr->nRowAvg = (int)(((nByte / nDoc) + p->nPgsz) / p->nPgsz);
+    assert( pCsr->nRowAvg>0 ); 
+    rc = sqlite3_reset(pStmt);
+    if( rc!=SQLITE_OK ) return rc;
+  }
+
+  *pnPage = pCsr->nRowAvg;
+  return SQLITE_OK;
+}
+
+/*
+** This function is called to select the tokens (if any) that will be 
+** deferred. The array aTC[] has already been populated when this is
+** called.
+**
+** This function is called once for each AND/NEAR cluster in the 
+** expression. Each invocation determines which tokens to defer within
+** the cluster with root node pRoot. See comments above the definition
+** of struct Fts3TokenAndCost for more details.
+**
+** If no error occurs, SQLITE_OK is returned and sqlite3Fts3DeferToken()
+** called on each token to defer. Otherwise, an SQLite error code is
+** returned.
+*/
+static int fts3EvalSelectDeferred(
+  Fts3Cursor *pCsr,               /* FTS Cursor handle */
+  Fts3Expr *pRoot,                /* Consider tokens with this root node */
+  Fts3TokenAndCost *aTC,          /* Array of expression tokens and costs */
+  int nTC                         /* Number of entries in aTC[] */
+){
+  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
+  int nDocSize = 0;               /* Number of pages per doc loaded */
+  int rc = SQLITE_OK;             /* Return code */
+  int ii;                         /* Iterator variable for various purposes */
+  int nOvfl = 0;                  /* Total overflow pages used by doclists */
+  int nToken = 0;                 /* Total number of tokens in cluster */
+
+  int nMinEst = 0;                /* The minimum count for any phrase so far. */
+  int nLoad4 = 1;                 /* (Phrases that will be loaded)^4. */
+
+  /* Tokens are never deferred for FTS tables created using the content=xxx
+  ** option. The reason being that it is not guaranteed that the content
+  ** table actually contains the same data as the index. To prevent this from
+  ** causing any problems, the deferred token optimization is completely
+  ** disabled for content=xxx tables. */
+  if( pTab->zContentTbl ){
+    return SQLITE_OK;
+  }
+
+  /* Count the tokens in this AND/NEAR cluster. If none of the doclists
+  ** associated with the tokens spill onto overflow pages, or if there is
+  ** only 1 token, exit early. No tokens to defer in this case. */
+  for(ii=0; ii<nTC; ii++){
+    if( aTC[ii].pRoot==pRoot ){
+      nOvfl += aTC[ii].nOvfl;
+      nToken++;
+    }
+  }
+  if( nOvfl==0 || nToken<2 ) return SQLITE_OK;
+
+  /* Obtain the average docsize (in pages). */
+  rc = fts3EvalAverageDocsize(pCsr, &nDocSize);
+  assert( rc!=SQLITE_OK || nDocSize>0 );
+
+
+  /* Iterate through all tokens in this AND/NEAR cluster, in ascending order 
+  ** of the number of overflow pages that will be loaded by the pager layer 
+  ** to retrieve the entire doclist for the token from the full-text index.
+  ** Load the doclists for tokens that are either:
+  **
+  **   a. The cheapest token in the entire query (i.e. the one visited by the
+  **      first iteration of this loop), or
+  **
+  **   b. Part of a multi-token phrase.
+  **
+  ** After each token doclist is loaded, merge it with the others from the
+  ** same phrase and count the number of documents that the merged doclist
+  ** contains. Set variable "nMinEst" to the smallest number of documents in 
+  ** any phrase doclist for which 1 or more token doclists have been loaded.
+  ** Let nOther be the number of other phrases for which it is certain that
+  ** one or more tokens will not be deferred.
+  **
+  ** Then, for each token, defer it if loading the doclist would result in
+  ** loading N or more overflow pages into memory, where N is computed as:
+  **
+  **    (nMinEst + 4^nOther - 1) / (4^nOther)
+  */
+  for(ii=0; ii<nToken && rc==SQLITE_OK; ii++){
+    int iTC;                      /* Used to iterate through aTC[] array. */
+    Fts3TokenAndCost *pTC = 0;    /* Set to cheapest remaining token. */
+
+    /* Set pTC to point to the cheapest remaining token. */
+    for(iTC=0; iTC<nTC; iTC++){
+      if( aTC[iTC].pToken && aTC[iTC].pRoot==pRoot 
+       && (!pTC || aTC[iTC].nOvfl<pTC->nOvfl) 
+      ){
+        pTC = &aTC[iTC];
+      }
+    }
+    assert( pTC );
+
+    if( ii && pTC->nOvfl>=((nMinEst+(nLoad4/4)-1)/(nLoad4/4))*nDocSize ){
+      /* The number of overflow pages to load for this (and therefore all
+      ** subsequent) tokens is greater than the estimated number of pages 
+      ** that will be loaded if all subsequent tokens are deferred.
+      */
+      Fts3PhraseToken *pToken = pTC->pToken;
+      rc = sqlite3Fts3DeferToken(pCsr, pToken, pTC->iCol);
+      fts3SegReaderCursorFree(pToken->pSegcsr);
+      pToken->pSegcsr = 0;
+    }else{
+      /* Set nLoad4 to the value of (4^nOther) for the next iteration of the
+      ** for-loop. Except, limit the value to 2^24 to prevent it from 
+      ** overflowing the 32-bit integer it is stored in. */
+      if( ii<12 ) nLoad4 = nLoad4*4;
+
+      if( ii==0 || (pTC->pPhrase->nToken>1 && ii!=nToken-1) ){
+        /* Either this is the cheapest token in the entire query, or it is
+        ** part of a multi-token phrase. Either way, the entire doclist will
+        ** (eventually) be loaded into memory. It may as well be now. */
+        Fts3PhraseToken *pToken = pTC->pToken;
+        int nList = 0;
+        char *pList = 0;
+        rc = fts3TermSelect(pTab, pToken, pTC->iCol, &nList, &pList);
+        assert( rc==SQLITE_OK || pList==0 );
+        if( rc==SQLITE_OK ){
+          rc = fts3EvalPhraseMergeToken(
+              pTab, pTC->pPhrase, pTC->iToken,pList,nList
+          );
+        }
+        if( rc==SQLITE_OK ){
+          int nCount;
+          nCount = fts3DoclistCountDocids(
+              pTC->pPhrase->doclist.aAll, pTC->pPhrase->doclist.nAll
+          );
+          if( ii==0 || nCount<nMinEst ) nMinEst = nCount;
+        }
+      }
+    }
+    pTC->pToken = 0;
+  }
+
+  return rc;
+}
+
+/*
+** This function is called from within the xFilter method. It initializes
+** the full-text query currently stored in pCsr->pExpr. To iterate through
+** the results of a query, the caller does:
+**
+**    fts3EvalStart(pCsr);
+**    while( 1 ){
+**      fts3EvalNext(pCsr);
+**      if( pCsr->bEof ) break;
+**      ... return row pCsr->iPrevId to the caller ...
+**    }
+*/
+static int fts3EvalStart(Fts3Cursor *pCsr){
+  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
+  int rc = SQLITE_OK;
+  int nToken = 0;
+  int nOr = 0;
+
+  /* Allocate a MultiSegReader for each token in the expression. */
+  fts3EvalAllocateReaders(pCsr, pCsr->pExpr, &nToken, &nOr, &rc);
+
+  /* Determine which, if any, tokens in the expression should be deferred. */
+#ifndef SQLITE_DISABLE_FTS4_DEFERRED
+  if( rc==SQLITE_OK && nToken>1 && pTab->bFts4 ){
+    Fts3TokenAndCost *aTC;
+    Fts3Expr **apOr;
+    aTC = (Fts3TokenAndCost *)sqlite3_malloc(
+        sizeof(Fts3TokenAndCost) * nToken
+      + sizeof(Fts3Expr *) * nOr * 2
+    );
+    apOr = (Fts3Expr **)&aTC[nToken];
+
+    if( !aTC ){
+      rc = SQLITE_NOMEM;
+    }else{
+      int ii;
+      Fts3TokenAndCost *pTC = aTC;
+      Fts3Expr **ppOr = apOr;
+
+      fts3EvalTokenCosts(pCsr, 0, pCsr->pExpr, &pTC, &ppOr, &rc);
+      nToken = (int)(pTC-aTC);
+      nOr = (int)(ppOr-apOr);
+
+      if( rc==SQLITE_OK ){
+        rc = fts3EvalSelectDeferred(pCsr, 0, aTC, nToken);
+        for(ii=0; rc==SQLITE_OK && ii<nOr; ii++){
+          rc = fts3EvalSelectDeferred(pCsr, apOr[ii], aTC, nToken);
+        }
+      }
+
+      sqlite3_free(aTC);
+    }
+  }
+#endif
+
+  fts3EvalStartReaders(pCsr, pCsr->pExpr, &rc);
+  return rc;
+}
+
+/*
+** Invalidate the current position list for phrase pPhrase.
+*/
+static void fts3EvalInvalidatePoslist(Fts3Phrase *pPhrase){
+  if( pPhrase->doclist.bFreeList ){
+    sqlite3_free(pPhrase->doclist.pList);
+  }
+  pPhrase->doclist.pList = 0;
+  pPhrase->doclist.nList = 0;
+  pPhrase->doclist.bFreeList = 0;
+}
+
+/*
+** This function is called to edit the position list associated with
+** the phrase object passed as the fifth argument according to a NEAR
+** condition. For example:
+**
+**     abc NEAR/5 "def ghi"
+**
+** Parameter nNear is passed the NEAR distance of the expression (5 in
+** the example above). When this function is called, *paPoslist points to
+** the position list, and *pnToken is the number of phrase tokens in, the
+** phrase on the other side of the NEAR operator to pPhrase. For example,
+** if pPhrase refers to the "def ghi" phrase, then *paPoslist points to
+** the position list associated with phrase "abc".
+**
+** All positions in the pPhrase position list that are not sufficiently
+** close to a position in the *paPoslist position list are removed. If this
+** leaves 0 positions, zero is returned. Otherwise, non-zero.
+**
+** Before returning, *paPoslist is set to point to the position lsit 
+** associated with pPhrase. And *pnToken is set to the number of tokens in
+** pPhrase.
+*/
+static int fts3EvalNearTrim(
+  int nNear,                      /* NEAR distance. As in "NEAR/nNear". */
+  char *aTmp,                     /* Temporary space to use */
+  char **paPoslist,               /* IN/OUT: Position list */
+  int *pnToken,                   /* IN/OUT: Tokens in phrase of *paPoslist */
+  Fts3Phrase *pPhrase             /* The phrase object to trim the doclist of */
+){
+  int nParam1 = nNear + pPhrase->nToken;
+  int nParam2 = nNear + *pnToken;
+  int nNew;
+  char *p2; 
+  char *pOut; 
+  int res;
+
+  assert( pPhrase->doclist.pList );
+
+  p2 = pOut = pPhrase->doclist.pList;
+  res = fts3PoslistNearMerge(
+    &pOut, aTmp, nParam1, nParam2, paPoslist, &p2
+  );
+  if( res ){
+    nNew = (int)(pOut - pPhrase->doclist.pList) - 1;
+    assert( pPhrase->doclist.pList[nNew]=='\0' );
+    assert( nNew<=pPhrase->doclist.nList && nNew>0 );
+    memset(&pPhrase->doclist.pList[nNew], 0, pPhrase->doclist.nList - nNew);
+    pPhrase->doclist.nList = nNew;
+    *paPoslist = pPhrase->doclist.pList;
+    *pnToken = pPhrase->nToken;
+  }
+
+  return res;
+}
+
+/*
+** This function is a no-op if *pRc is other than SQLITE_OK when it is called.
+** Otherwise, it advances the expression passed as the second argument to
+** point to the next matching row in the database. Expressions iterate through
+** matching rows in docid order. Ascending order if Fts3Cursor.bDesc is zero,
+** or descending if it is non-zero.
+**
+** If an error occurs, *pRc is set to an SQLite error code. Otherwise, if
+** successful, the following variables in pExpr are set:
+**
+**   Fts3Expr.bEof                (non-zero if EOF - there is no next row)
+**   Fts3Expr.iDocid              (valid if bEof==0. The docid of the next row)
+**
+** If the expression is of type FTSQUERY_PHRASE, and the expression is not
+** at EOF, then the following variables are populated with the position list
+** for the phrase for the visited row:
+**
+**   FTs3Expr.pPhrase->doclist.nList        (length of pList in bytes)
+**   FTs3Expr.pPhrase->doclist.pList        (pointer to position list)
+**
+** It says above that this function advances the expression to the next
+** matching row. This is usually true, but there are the following exceptions:
+**
+**   1. Deferred tokens are not taken into account. If a phrase consists
+**      entirely of deferred tokens, it is assumed to match every row in
+**      the db. In this case the position-list is not populated at all. 
+**
+**      Or, if a phrase contains one or more deferred tokens and one or
+**      more non-deferred tokens, then the expression is advanced to the 
+**      next possible match, considering only non-deferred tokens. In other
+**      words, if the phrase is "A B C", and "B" is deferred, the expression
+**      is advanced to the next row that contains an instance of "A * C", 
+**      where "*" may match any single token. The position list in this case
+**      is populated as for "A * C" before returning.
+**
+**   2. NEAR is treated as AND. If the expression is "x NEAR y", it is 
+**      advanced to point to the next row that matches "x AND y".
+** 
+** See sqlite3Fts3EvalTestDeferred() for details on testing if a row is
+** really a match, taking into account deferred tokens and NEAR operators.
+*/
+static void fts3EvalNextRow(
+  Fts3Cursor *pCsr,               /* FTS Cursor handle */
+  Fts3Expr *pExpr,                /* Expr. to advance to next matching row */
+  int *pRc                        /* IN/OUT: Error code */
+){
+  if( *pRc==SQLITE_OK ){
+    int bDescDoclist = pCsr->bDesc;         /* Used by DOCID_CMP() macro */
+    assert( pExpr->bEof==0 );
+    pExpr->bStart = 1;
+
+    switch( pExpr->eType ){
+      case FTSQUERY_NEAR:
+      case FTSQUERY_AND: {
+        Fts3Expr *pLeft = pExpr->pLeft;
+        Fts3Expr *pRight = pExpr->pRight;
+        assert( !pLeft->bDeferred || !pRight->bDeferred );
+
+        if( pLeft->bDeferred ){
+          /* LHS is entirely deferred. So we assume it matches every row.
+          ** Advance the RHS iterator to find the next row visited. */
+          fts3EvalNextRow(pCsr, pRight, pRc);
+          pExpr->iDocid = pRight->iDocid;
+          pExpr->bEof = pRight->bEof;
+        }else if( pRight->bDeferred ){
+          /* RHS is entirely deferred. So we assume it matches every row.
+          ** Advance the LHS iterator to find the next row visited. */
+          fts3EvalNextRow(pCsr, pLeft, pRc);
+          pExpr->iDocid = pLeft->iDocid;
+          pExpr->bEof = pLeft->bEof;
+        }else{
+          /* Neither the RHS or LHS are deferred. */
+          fts3EvalNextRow(pCsr, pLeft, pRc);
+          fts3EvalNextRow(pCsr, pRight, pRc);
+          while( !pLeft->bEof && !pRight->bEof && *pRc==SQLITE_OK ){
+            sqlite3_int64 iDiff = DOCID_CMP(pLeft->iDocid, pRight->iDocid);
+            if( iDiff==0 ) break;
+            if( iDiff<0 ){
+              fts3EvalNextRow(pCsr, pLeft, pRc);
+            }else{
+              fts3EvalNextRow(pCsr, pRight, pRc);
+            }
+          }
+          pExpr->iDocid = pLeft->iDocid;
+          pExpr->bEof = (pLeft->bEof || pRight->bEof);
+          if( pExpr->eType==FTSQUERY_NEAR && pExpr->bEof ){
+            if( pRight->pPhrase && pRight->pPhrase->doclist.aAll ){
+              Fts3Doclist *pDl = &pRight->pPhrase->doclist;
+              while( *pRc==SQLITE_OK && pRight->bEof==0 ){
+                memset(pDl->pList, 0, pDl->nList);
+                fts3EvalNextRow(pCsr, pRight, pRc);
+              }
+            }
+            if( pLeft->pPhrase && pLeft->pPhrase->doclist.aAll ){
+              Fts3Doclist *pDl = &pLeft->pPhrase->doclist;
+              while( *pRc==SQLITE_OK && pLeft->bEof==0 ){
+                memset(pDl->pList, 0, pDl->nList);
+                fts3EvalNextRow(pCsr, pLeft, pRc);
+              }
+            }
+          }
+        }
+        break;
+      }
+  
+      case FTSQUERY_OR: {
+        Fts3Expr *pLeft = pExpr->pLeft;
+        Fts3Expr *pRight = pExpr->pRight;
+        sqlite3_int64 iCmp = DOCID_CMP(pLeft->iDocid, pRight->iDocid);
+
+        assert( pLeft->bStart || pLeft->iDocid==pRight->iDocid );
+        assert( pRight->bStart || pLeft->iDocid==pRight->iDocid );
+
+        if( pRight->bEof || (pLeft->bEof==0 && iCmp<0) ){
+          fts3EvalNextRow(pCsr, pLeft, pRc);
+        }else if( pLeft->bEof || (pRight->bEof==0 && iCmp>0) ){
+          fts3EvalNextRow(pCsr, pRight, pRc);
+        }else{
+          fts3EvalNextRow(pCsr, pLeft, pRc);
+          fts3EvalNextRow(pCsr, pRight, pRc);
+        }
+
+        pExpr->bEof = (pLeft->bEof && pRight->bEof);
+        iCmp = DOCID_CMP(pLeft->iDocid, pRight->iDocid);
+        if( pRight->bEof || (pLeft->bEof==0 &&  iCmp<0) ){
+          pExpr->iDocid = pLeft->iDocid;
+        }else{
+          pExpr->iDocid = pRight->iDocid;
+        }
+
+        break;
+      }
+
+      case FTSQUERY_NOT: {
+        Fts3Expr *pLeft = pExpr->pLeft;
+        Fts3Expr *pRight = pExpr->pRight;
+
+        if( pRight->bStart==0 ){
+          fts3EvalNextRow(pCsr, pRight, pRc);
+          assert( *pRc!=SQLITE_OK || pRight->bStart );
+        }
+
+        fts3EvalNextRow(pCsr, pLeft, pRc);
+        if( pLeft->bEof==0 ){
+          while( !*pRc 
+              && !pRight->bEof 
+              && DOCID_CMP(pLeft->iDocid, pRight->iDocid)>0 
+          ){
+            fts3EvalNextRow(pCsr, pRight, pRc);
+          }
+        }
+        pExpr->iDocid = pLeft->iDocid;
+        pExpr->bEof = pLeft->bEof;
+        break;
+      }
+
+      default: {
+        Fts3Phrase *pPhrase = pExpr->pPhrase;
+        fts3EvalInvalidatePoslist(pPhrase);
+        *pRc = fts3EvalPhraseNext(pCsr, pPhrase, &pExpr->bEof);
+        pExpr->iDocid = pPhrase->doclist.iDocid;
+        break;
+      }
+    }
+  }
+}
+
+/*
+** If *pRc is not SQLITE_OK, or if pExpr is not the root node of a NEAR
+** cluster, then this function returns 1 immediately.
+**
+** Otherwise, it checks if the current row really does match the NEAR 
+** expression, using the data currently stored in the position lists 
+** (Fts3Expr->pPhrase.doclist.pList/nList) for each phrase in the expression. 
+**
+** If the current row is a match, the position list associated with each
+** phrase in the NEAR expression is edited in place to contain only those
+** phrase instances sufficiently close to their peers to satisfy all NEAR
+** constraints. In this case it returns 1. If the NEAR expression does not 
+** match the current row, 0 is returned. The position lists may or may not
+** be edited if 0 is returned.
+*/
+static int fts3EvalNearTest(Fts3Expr *pExpr, int *pRc){
+  int res = 1;
+
+  /* The following block runs if pExpr is the root of a NEAR query.
+  ** For example, the query:
+  **
+  **         "w" NEAR "x" NEAR "y" NEAR "z"
+  **
+  ** which is represented in tree form as:
+  **
+  **                               |
+  **                          +--NEAR--+      <-- root of NEAR query
+  **                          |        |
+  **                     +--NEAR--+   "z"
+  **                     |        |
+  **                +--NEAR--+   "y"
+  **                |        |
+  **               "w"      "x"
+  **
+  ** The right-hand child of a NEAR node is always a phrase. The 
+  ** left-hand child may be either a phrase or a NEAR node. There are
+  ** no exceptions to this - it's the way the parser in fts3_expr.c works.
+  */
+  if( *pRc==SQLITE_OK 
+   && pExpr->eType==FTSQUERY_NEAR 
+   && pExpr->bEof==0
+   && (pExpr->pParent==0 || pExpr->pParent->eType!=FTSQUERY_NEAR)
+  ){
+    Fts3Expr *p; 
+    int nTmp = 0;                 /* Bytes of temp space */
+    char *aTmp;                   /* Temp space for PoslistNearMerge() */
+
+    /* Allocate temporary working space. */
+    for(p=pExpr; p->pLeft; p=p->pLeft){
+      nTmp += p->pRight->pPhrase->doclist.nList;
+    }
+    nTmp += p->pPhrase->doclist.nList;
+    if( nTmp==0 ){
+      res = 0;
+    }else{
+      aTmp = sqlite3_malloc(nTmp*2);
+      if( !aTmp ){
+        *pRc = SQLITE_NOMEM;
+        res = 0;
+      }else{
+        char *aPoslist = p->pPhrase->doclist.pList;
+        int nToken = p->pPhrase->nToken;
+
+        for(p=p->pParent;res && p && p->eType==FTSQUERY_NEAR; p=p->pParent){
+          Fts3Phrase *pPhrase = p->pRight->pPhrase;
+          int nNear = p->nNear;
+          res = fts3EvalNearTrim(nNear, aTmp, &aPoslist, &nToken, pPhrase);
+        }
+
+        aPoslist = pExpr->pRight->pPhrase->doclist.pList;
+        nToken = pExpr->pRight->pPhrase->nToken;
+        for(p=pExpr->pLeft; p && res; p=p->pLeft){
+          int nNear;
+          Fts3Phrase *pPhrase;
+          assert( p->pParent && p->pParent->pLeft==p );
+          nNear = p->pParent->nNear;
+          pPhrase = (
+              p->eType==FTSQUERY_NEAR ? p->pRight->pPhrase : p->pPhrase
+              );
+          res = fts3EvalNearTrim(nNear, aTmp, &aPoslist, &nToken, pPhrase);
+        }
+      }
+
+      sqlite3_free(aTmp);
+    }
+  }
+
+  return res;
+}
+
+/*
+** This function is a helper function for sqlite3Fts3EvalTestDeferred().
+** Assuming no error occurs or has occurred, It returns non-zero if the
+** expression passed as the second argument matches the row that pCsr 
+** currently points to, or zero if it does not.
+**
+** If *pRc is not SQLITE_OK when this function is called, it is a no-op.
+** If an error occurs during execution of this function, *pRc is set to 
+** the appropriate SQLite error code. In this case the returned value is 
+** undefined.
+*/
+static int fts3EvalTestExpr(
+  Fts3Cursor *pCsr,               /* FTS cursor handle */
+  Fts3Expr *pExpr,                /* Expr to test. May or may not be root. */
+  int *pRc                        /* IN/OUT: Error code */
+){
+  int bHit = 1;                   /* Return value */
+  if( *pRc==SQLITE_OK ){
+    switch( pExpr->eType ){
+      case FTSQUERY_NEAR:
+      case FTSQUERY_AND:
+        bHit = (
+            fts3EvalTestExpr(pCsr, pExpr->pLeft, pRc)
+         && fts3EvalTestExpr(pCsr, pExpr->pRight, pRc)
+         && fts3EvalNearTest(pExpr, pRc)
+        );
+
+        /* If the NEAR expression does not match any rows, zero the doclist for 
+        ** all phrases involved in the NEAR. This is because the snippet(),
+        ** offsets() and matchinfo() functions are not supposed to recognize 
+        ** any instances of phrases that are part of unmatched NEAR queries. 
+        ** For example if this expression:
+        **
+        **    ... MATCH 'a OR (b NEAR c)'
+        **
+        ** is matched against a row containing:
+        **
+        **        'a b d e'
+        **
+        ** then any snippet() should ony highlight the "a" term, not the "b"
+        ** (as "b" is part of a non-matching NEAR clause).
+        */
+        if( bHit==0 
+         && pExpr->eType==FTSQUERY_NEAR 
+         && (pExpr->pParent==0 || pExpr->pParent->eType!=FTSQUERY_NEAR)
+        ){
+          Fts3Expr *p;
+          for(p=pExpr; p->pPhrase==0; p=p->pLeft){
+            if( p->pRight->iDocid==pCsr->iPrevId ){
+              fts3EvalInvalidatePoslist(p->pRight->pPhrase);
+            }
+          }
+          if( p->iDocid==pCsr->iPrevId ){
+            fts3EvalInvalidatePoslist(p->pPhrase);
+          }
+        }
+
+        break;
+
+      case FTSQUERY_OR: {
+        int bHit1 = fts3EvalTestExpr(pCsr, pExpr->pLeft, pRc);
+        int bHit2 = fts3EvalTestExpr(pCsr, pExpr->pRight, pRc);
+        bHit = bHit1 || bHit2;
+        break;
+      }
+
+      case FTSQUERY_NOT:
+        bHit = (
+            fts3EvalTestExpr(pCsr, pExpr->pLeft, pRc)
+         && !fts3EvalTestExpr(pCsr, pExpr->pRight, pRc)
+        );
+        break;
+
+      default: {
+#ifndef SQLITE_DISABLE_FTS4_DEFERRED
+        if( pCsr->pDeferred 
+         && (pExpr->iDocid==pCsr->iPrevId || pExpr->bDeferred)
+        ){
+          Fts3Phrase *pPhrase = pExpr->pPhrase;
+          assert( pExpr->bDeferred || pPhrase->doclist.bFreeList==0 );
+          if( pExpr->bDeferred ){
+            fts3EvalInvalidatePoslist(pPhrase);
+          }
+          *pRc = fts3EvalDeferredPhrase(pCsr, pPhrase);
+          bHit = (pPhrase->doclist.pList!=0);
+          pExpr->iDocid = pCsr->iPrevId;
+        }else
+#endif
+        {
+          bHit = (pExpr->bEof==0 && pExpr->iDocid==pCsr->iPrevId);
+        }
+        break;
+      }
+    }
+  }
+  return bHit;
+}
+
+/*
+** This function is called as the second part of each xNext operation when
+** iterating through the results of a full-text query. At this point the
+** cursor points to a row that matches the query expression, with the
+** following caveats:
+**
+**   * Up until this point, "NEAR" operators in the expression have been
+**     treated as "AND".
+**
+**   * Deferred tokens have not yet been considered.
+**
+** If *pRc is not SQLITE_OK when this function is called, it immediately
+** returns 0. Otherwise, it tests whether or not after considering NEAR
+** operators and deferred tokens the current row is still a match for the
+** expression. It returns 1 if both of the following are true:
+**
+**   1. *pRc is SQLITE_OK when this function returns, and
+**
+**   2. After scanning the current FTS table row for the deferred tokens,
+**      it is determined that the row does *not* match the query.
+**
+** Or, if no error occurs and it seems the current row does match the FTS
+** query, return 0.
+*/
+SQLITE_PRIVATE int sqlite3Fts3EvalTestDeferred(Fts3Cursor *pCsr, int *pRc){
+  int rc = *pRc;
+  int bMiss = 0;
+  if( rc==SQLITE_OK ){
+
+    /* If there are one or more deferred tokens, load the current row into
+    ** memory and scan it to determine the position list for each deferred
+    ** token. Then, see if this row is really a match, considering deferred
+    ** tokens and NEAR operators (neither of which were taken into account
+    ** earlier, by fts3EvalNextRow()). 
+    */
+    if( pCsr->pDeferred ){
+      rc = fts3CursorSeek(0, pCsr);
+      if( rc==SQLITE_OK ){
+        rc = sqlite3Fts3CacheDeferredDoclists(pCsr);
+      }
+    }
+    bMiss = (0==fts3EvalTestExpr(pCsr, pCsr->pExpr, &rc));
+
+    /* Free the position-lists accumulated for each deferred token above. */
+    sqlite3Fts3FreeDeferredDoclists(pCsr);
+    *pRc = rc;
+  }
+  return (rc==SQLITE_OK && bMiss);
+}
+
+/*
+** Advance to the next document that matches the FTS expression in
+** Fts3Cursor.pExpr.
+*/
+static int fts3EvalNext(Fts3Cursor *pCsr){
+  int rc = SQLITE_OK;             /* Return Code */
+  Fts3Expr *pExpr = pCsr->pExpr;
+  assert( pCsr->isEof==0 );
+  if( pExpr==0 ){
+    pCsr->isEof = 1;
+  }else{
+    do {
+      if( pCsr->isRequireSeek==0 ){
+        sqlite3_reset(pCsr->pStmt);
+      }
+      assert( sqlite3_data_count(pCsr->pStmt)==0 );
+      fts3EvalNextRow(pCsr, pExpr, &rc);
+      pCsr->isEof = pExpr->bEof;
+      pCsr->isRequireSeek = 1;
+      pCsr->isMatchinfoNeeded = 1;
+      pCsr->iPrevId = pExpr->iDocid;
+    }while( pCsr->isEof==0 && sqlite3Fts3EvalTestDeferred(pCsr, &rc) );
+  }
+
+  /* Check if the cursor is past the end of the docid range specified
+  ** by Fts3Cursor.iMinDocid/iMaxDocid. If so, set the EOF flag.  */
+  if( rc==SQLITE_OK && (
+        (pCsr->bDesc==0 && pCsr->iPrevId>pCsr->iMaxDocid)
+     || (pCsr->bDesc!=0 && pCsr->iPrevId<pCsr->iMinDocid)
+  )){
+    pCsr->isEof = 1;
+  }
+
+  return rc;
+}
+
+/*
+** Restart interation for expression pExpr so that the next call to
+** fts3EvalNext() visits the first row. Do not allow incremental 
+** loading or merging of phrase doclists for this iteration.
+**
+** If *pRc is other than SQLITE_OK when this function is called, it is
+** a no-op. If an error occurs within this function, *pRc is set to an
+** SQLite error code before returning.
+*/
+static void fts3EvalRestart(
+  Fts3Cursor *pCsr,
+  Fts3Expr *pExpr,
+  int *pRc
+){
+  if( pExpr && *pRc==SQLITE_OK ){
+    Fts3Phrase *pPhrase = pExpr->pPhrase;
+
+    if( pPhrase ){
+      fts3EvalInvalidatePoslist(pPhrase);
+      if( pPhrase->bIncr ){
+        int i;
+        for(i=0; i<pPhrase->nToken; i++){
+          Fts3PhraseToken *pToken = &pPhrase->aToken[i];
+          assert( pToken->pDeferred==0 );
+          if( pToken->pSegcsr ){
+            sqlite3Fts3MsrIncrRestart(pToken->pSegcsr);
+          }
+        }
+        *pRc = fts3EvalPhraseStart(pCsr, 0, pPhrase);
+      }
+      pPhrase->doclist.pNextDocid = 0;
+      pPhrase->doclist.iDocid = 0;
+      pPhrase->pOrPoslist = 0;
+    }
+
+    pExpr->iDocid = 0;
+    pExpr->bEof = 0;
+    pExpr->bStart = 0;
+
+    fts3EvalRestart(pCsr, pExpr->pLeft, pRc);
+    fts3EvalRestart(pCsr, pExpr->pRight, pRc);
+  }
+}
+
+/*
+** After allocating the Fts3Expr.aMI[] array for each phrase in the 
+** expression rooted at pExpr, the cursor iterates through all rows matched
+** by pExpr, calling this function for each row. This function increments
+** the values in Fts3Expr.aMI[] according to the position-list currently
+** found in Fts3Expr.pPhrase->doclist.pList for each of the phrase 
+** expression nodes.
+*/
+static void fts3EvalUpdateCounts(Fts3Expr *pExpr){
+  if( pExpr ){
+    Fts3Phrase *pPhrase = pExpr->pPhrase;
+    if( pPhrase && pPhrase->doclist.pList ){
+      int iCol = 0;
+      char *p = pPhrase->doclist.pList;
+
+      assert( *p );
+      while( 1 ){
+        u8 c = 0;
+        int iCnt = 0;
+        while( 0xFE & (*p | c) ){
+          if( (c&0x80)==0 ) iCnt++;
+          c = *p++ & 0x80;
+        }
+
+        /* aMI[iCol*3 + 1] = Number of occurrences
+        ** aMI[iCol*3 + 2] = Number of rows containing at least one instance
+        */
+        pExpr->aMI[iCol*3 + 1] += iCnt;
+        pExpr->aMI[iCol*3 + 2] += (iCnt>0);
+        if( *p==0x00 ) break;
+        p++;
+        p += fts3GetVarint32(p, &iCol);
+      }
+    }
+
+    fts3EvalUpdateCounts(pExpr->pLeft);
+    fts3EvalUpdateCounts(pExpr->pRight);
+  }
+}
+
+/*
+** Expression pExpr must be of type FTSQUERY_PHRASE.
+**
+** If it is not already allocated and populated, this function allocates and
+** populates the Fts3Expr.aMI[] array for expression pExpr. If pExpr is part
+** of a NEAR expression, then it also allocates and populates the same array
+** for all other phrases that are part of the NEAR expression.
+**
+** SQLITE_OK is returned if the aMI[] array is successfully allocated and
+** populated. Otherwise, if an error occurs, an SQLite error code is returned.
+*/
+static int fts3EvalGatherStats(
+  Fts3Cursor *pCsr,               /* Cursor object */
+  Fts3Expr *pExpr                 /* FTSQUERY_PHRASE expression */
+){
+  int rc = SQLITE_OK;             /* Return code */
+
+  assert( pExpr->eType==FTSQUERY_PHRASE );
+  if( pExpr->aMI==0 ){
+    Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
+    Fts3Expr *pRoot;                /* Root of NEAR expression */
+    Fts3Expr *p;                    /* Iterator used for several purposes */
+
+    sqlite3_int64 iPrevId = pCsr->iPrevId;
+    sqlite3_int64 iDocid;
+    u8 bEof;
+
+    /* Find the root of the NEAR expression */
+    pRoot = pExpr;
+    while( pRoot->pParent && pRoot->pParent->eType==FTSQUERY_NEAR ){
+      pRoot = pRoot->pParent;
+    }
+    iDocid = pRoot->iDocid;
+    bEof = pRoot->bEof;
+    assert( pRoot->bStart );
+
+    /* Allocate space for the aMSI[] array of each FTSQUERY_PHRASE node */
+    for(p=pRoot; p; p=p->pLeft){
+      Fts3Expr *pE = (p->eType==FTSQUERY_PHRASE?p:p->pRight);
+      assert( pE->aMI==0 );
+      pE->aMI = (u32 *)sqlite3_malloc(pTab->nColumn * 3 * sizeof(u32));
+      if( !pE->aMI ) return SQLITE_NOMEM;
+      memset(pE->aMI, 0, pTab->nColumn * 3 * sizeof(u32));
+    }
+
+    fts3EvalRestart(pCsr, pRoot, &rc);
+
+    while( pCsr->isEof==0 && rc==SQLITE_OK ){
+
+      do {
+        /* Ensure the %_content statement is reset. */
+        if( pCsr->isRequireSeek==0 ) sqlite3_reset(pCsr->pStmt);
+        assert( sqlite3_data_count(pCsr->pStmt)==0 );
+
+        /* Advance to the next document */
+        fts3EvalNextRow(pCsr, pRoot, &rc);
+        pCsr->isEof = pRoot->bEof;
+        pCsr->isRequireSeek = 1;
+        pCsr->isMatchinfoNeeded = 1;
+        pCsr->iPrevId = pRoot->iDocid;
+      }while( pCsr->isEof==0 
+           && pRoot->eType==FTSQUERY_NEAR 
+           && sqlite3Fts3EvalTestDeferred(pCsr, &rc) 
+      );
+
+      if( rc==SQLITE_OK && pCsr->isEof==0 ){
+        fts3EvalUpdateCounts(pRoot);
+      }
+    }
+
+    pCsr->isEof = 0;
+    pCsr->iPrevId = iPrevId;
+
+    if( bEof ){
+      pRoot->bEof = bEof;
+    }else{
+      /* Caution: pRoot may iterate through docids in ascending or descending
+      ** order. For this reason, even though it seems more defensive, the 
+      ** do loop can not be written:
+      **
+      **   do {...} while( pRoot->iDocid<iDocid && rc==SQLITE_OK );
+      */
+      fts3EvalRestart(pCsr, pRoot, &rc);
+      do {
+        fts3EvalNextRow(pCsr, pRoot, &rc);
+        assert( pRoot->bEof==0 );
+      }while( pRoot->iDocid!=iDocid && rc==SQLITE_OK );
+    }
+  }
+  return rc;
+}
+
+/*
+** This function is used by the matchinfo() module to query a phrase 
+** expression node for the following information:
+**
+**   1. The total number of occurrences of the phrase in each column of 
+**      the FTS table (considering all rows), and
+**
+**   2. For each column, the number of rows in the table for which the
+**      column contains at least one instance of the phrase.
+**
+** If no error occurs, SQLITE_OK is returned and the values for each column
+** written into the array aiOut as follows:
+**
+**   aiOut[iCol*3 + 1] = Number of occurrences
+**   aiOut[iCol*3 + 2] = Number of rows containing at least one instance
+**
+** Caveats:
+**
+**   * If a phrase consists entirely of deferred tokens, then all output 
+**     values are set to the number of documents in the table. In other
+**     words we assume that very common tokens occur exactly once in each 
+**     column of each row of the table.
+**
+**   * If a phrase contains some deferred tokens (and some non-deferred 
+**     tokens), count the potential occurrence identified by considering
+**     the non-deferred tokens instead of actual phrase occurrences.
+**
+**   * If the phrase is part of a NEAR expression, then only phrase instances
+**     that meet the NEAR constraint are included in the counts.
+*/
+SQLITE_PRIVATE int sqlite3Fts3EvalPhraseStats(
+  Fts3Cursor *pCsr,               /* FTS cursor handle */
+  Fts3Expr *pExpr,                /* Phrase expression */
+  u32 *aiOut                      /* Array to write results into (see above) */
+){
+  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
+  int rc = SQLITE_OK;
+  int iCol;
+
+  if( pExpr->bDeferred && pExpr->pParent->eType!=FTSQUERY_NEAR ){
+    assert( pCsr->nDoc>0 );
+    for(iCol=0; iCol<pTab->nColumn; iCol++){
+      aiOut[iCol*3 + 1] = (u32)pCsr->nDoc;
+      aiOut[iCol*3 + 2] = (u32)pCsr->nDoc;
+    }
+  }else{
+    rc = fts3EvalGatherStats(pCsr, pExpr);
+    if( rc==SQLITE_OK ){
+      assert( pExpr->aMI );
+      for(iCol=0; iCol<pTab->nColumn; iCol++){
+        aiOut[iCol*3 + 1] = pExpr->aMI[iCol*3 + 1];
+        aiOut[iCol*3 + 2] = pExpr->aMI[iCol*3 + 2];
+      }
+    }
+  }
+
+  return rc;
+}
+
+/*
+** The expression pExpr passed as the second argument to this function
+** must be of type FTSQUERY_PHRASE. 
+**
+** The returned value is either NULL or a pointer to a buffer containing
+** a position-list indicating the occurrences of the phrase in column iCol
+** of the current row. 
+**
+** More specifically, the returned buffer contains 1 varint for each 
+** occurrence of the phrase in the column, stored using the normal (delta+2) 
+** compression and is terminated by either an 0x01 or 0x00 byte. For example,
+** if the requested column contains "a b X c d X X" and the position-list
+** for 'X' is requested, the buffer returned may contain:
+**
+**     0x04 0x05 0x03 0x01   or   0x04 0x05 0x03 0x00
+**
+** This function works regardless of whether or not the phrase is deferred,
+** incremental, or neither.
+*/
+SQLITE_PRIVATE int sqlite3Fts3EvalPhrasePoslist(
+  Fts3Cursor *pCsr,               /* FTS3 cursor object */
+  Fts3Expr *pExpr,                /* Phrase to return doclist for */
+  int iCol,                       /* Column to return position list for */
+  char **ppOut                    /* OUT: Pointer to position list */
+){
+  Fts3Phrase *pPhrase = pExpr->pPhrase;
+  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
+  char *pIter;
+  int iThis;
+  sqlite3_int64 iDocid;
+
+  /* If this phrase is applies specifically to some column other than 
+  ** column iCol, return a NULL pointer.  */
+  *ppOut = 0;
+  assert( iCol>=0 && iCol<pTab->nColumn );
+  if( (pPhrase->iColumn<pTab->nColumn && pPhrase->iColumn!=iCol) ){
+    return SQLITE_OK;
+  }
+
+  iDocid = pExpr->iDocid;
+  pIter = pPhrase->doclist.pList;
+  if( iDocid!=pCsr->iPrevId || pExpr->bEof ){
+    int rc = SQLITE_OK;
+    int bDescDoclist = pTab->bDescIdx;      /* For DOCID_CMP macro */
+    int bOr = 0;
+    u8 bTreeEof = 0;
+    Fts3Expr *p;                  /* Used to iterate from pExpr to root */
+    Fts3Expr *pNear;              /* Most senior NEAR ancestor (or pExpr) */
+    int bMatch;
+
+    /* Check if this phrase descends from an OR expression node. If not, 
+    ** return NULL. Otherwise, the entry that corresponds to docid 
+    ** pCsr->iPrevId may lie earlier in the doclist buffer. Or, if the
+    ** tree that the node is part of has been marked as EOF, but the node
+    ** itself is not EOF, then it may point to an earlier entry. */
+    pNear = pExpr;
+    for(p=pExpr->pParent; p; p=p->pParent){
+      if( p->eType==FTSQUERY_OR ) bOr = 1;
+      if( p->eType==FTSQUERY_NEAR ) pNear = p;
+      if( p->bEof ) bTreeEof = 1;
+    }
+    if( bOr==0 ) return SQLITE_OK;
+
+    /* This is the descendent of an OR node. In this case we cannot use
+    ** an incremental phrase. Load the entire doclist for the phrase
+    ** into memory in this case.  */
+    if( pPhrase->bIncr ){
+      int bEofSave = pNear->bEof;
+      fts3EvalRestart(pCsr, pNear, &rc);
+      while( rc==SQLITE_OK && !pNear->bEof ){
+        fts3EvalNextRow(pCsr, pNear, &rc);
+        if( bEofSave==0 && pNear->iDocid==iDocid ) break;
+      }
+      assert( rc!=SQLITE_OK || pPhrase->bIncr==0 );
+    }
+    if( bTreeEof ){
+      while( rc==SQLITE_OK && !pNear->bEof ){
+        fts3EvalNextRow(pCsr, pNear, &rc);
+      }
+    }
+    if( rc!=SQLITE_OK ) return rc;
+
+    bMatch = 1;
+    for(p=pNear; p; p=p->pLeft){
+      u8 bEof = 0;
+      Fts3Expr *pTest = p;
+      Fts3Phrase *pPh;
+      assert( pTest->eType==FTSQUERY_NEAR || pTest->eType==FTSQUERY_PHRASE );
+      if( pTest->eType==FTSQUERY_NEAR ) pTest = pTest->pRight;
+      assert( pTest->eType==FTSQUERY_PHRASE );
+      pPh = pTest->pPhrase;
+
+      pIter = pPh->pOrPoslist;
+      iDocid = pPh->iOrDocid;
+      if( pCsr->bDesc==bDescDoclist ){
+        bEof = !pPh->doclist.nAll ||
+          (pIter >= (pPh->doclist.aAll + pPh->doclist.nAll));
+        while( (pIter==0 || DOCID_CMP(iDocid, pCsr->iPrevId)<0 ) && bEof==0 ){
+          sqlite3Fts3DoclistNext(
+              bDescDoclist, pPh->doclist.aAll, pPh->doclist.nAll, 
+              &pIter, &iDocid, &bEof
+          );
+        }
+      }else{
+        bEof = !pPh->doclist.nAll || (pIter && pIter<=pPh->doclist.aAll);
+        while( (pIter==0 || DOCID_CMP(iDocid, pCsr->iPrevId)>0 ) && bEof==0 ){
+          int dummy;
+          sqlite3Fts3DoclistPrev(
+              bDescDoclist, pPh->doclist.aAll, pPh->doclist.nAll, 
+              &pIter, &iDocid, &dummy, &bEof
+              );
+        }
+      }
+      pPh->pOrPoslist = pIter;
+      pPh->iOrDocid = iDocid;
+      if( bEof || iDocid!=pCsr->iPrevId ) bMatch = 0;
+    }
+
+    if( bMatch ){
+      pIter = pPhrase->pOrPoslist;
+    }else{
+      pIter = 0;
+    }
+  }
+  if( pIter==0 ) return SQLITE_OK;
+
+  if( *pIter==0x01 ){
+    pIter++;
+    pIter += fts3GetVarint32(pIter, &iThis);
+  }else{
+    iThis = 0;
+  }
+  while( iThis<iCol ){
+    fts3ColumnlistCopy(0, &pIter);
+    if( *pIter==0x00 ) return SQLITE_OK;
+    pIter++;
+    pIter += fts3GetVarint32(pIter, &iThis);
+  }
+  if( *pIter==0x00 ){
+    pIter = 0;
+  }
+
+  *ppOut = ((iCol==iThis)?pIter:0);
+  return SQLITE_OK;
+}
+
+/*
+** Free all components of the Fts3Phrase structure that were allocated by
+** the eval module. Specifically, this means to free:
+**
+**   * the contents of pPhrase->doclist, and
+**   * any Fts3MultiSegReader objects held by phrase tokens.
+*/
+SQLITE_PRIVATE void sqlite3Fts3EvalPhraseCleanup(Fts3Phrase *pPhrase){
+  if( pPhrase ){
+    int i;
+    sqlite3_free(pPhrase->doclist.aAll);
+    fts3EvalInvalidatePoslist(pPhrase);
+    memset(&pPhrase->doclist, 0, sizeof(Fts3Doclist));
+    for(i=0; i<pPhrase->nToken; i++){
+      fts3SegReaderCursorFree(pPhrase->aToken[i].pSegcsr);
+      pPhrase->aToken[i].pSegcsr = 0;
+    }
+  }
+}
+
+
+/*
+** Return SQLITE_CORRUPT_VTAB.
+*/
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE int sqlite3Fts3Corrupt(){
+  return SQLITE_CORRUPT_VTAB;
+}
+#endif
+
+#if !SQLITE_CORE
+/*
+** Initialize API pointer table, if required.
+*/
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+SQLITE_API int sqlite3_fts3_init(
+  sqlite3 *db, 
+  char **pzErrMsg,
+  const sqlite3_api_routines *pApi
+){
+  SQLITE_EXTENSION_INIT2(pApi)
+  return sqlite3Fts3Init(db);
+}
+#endif
+
+#endif
+
+/************** End of fts3.c ************************************************/
+/************** Begin file fts3_aux.c ****************************************/
+/*
+** 2011 Jan 27
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+*/
+/* #include "fts3Int.h" */
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
+
+/* #include <string.h> */
+/* #include <assert.h> */
+
+typedef struct Fts3auxTable Fts3auxTable;
+typedef struct Fts3auxCursor Fts3auxCursor;
+
+struct Fts3auxTable {
+  sqlite3_vtab base;              /* Base class used by SQLite core */
+  Fts3Table *pFts3Tab;
+};
+
+struct Fts3auxCursor {
+  sqlite3_vtab_cursor base;       /* Base class used by SQLite core */
+  Fts3MultiSegReader csr;        /* Must be right after "base" */
+  Fts3SegFilter filter;
+  char *zStop;
+  int nStop;                      /* Byte-length of string zStop */
+  int iLangid;                    /* Language id to query */
+  int isEof;                      /* True if cursor is at EOF */
+  sqlite3_int64 iRowid;           /* Current rowid */
+
+  int iCol;                       /* Current value of 'col' column */
+  int nStat;                      /* Size of aStat[] array */
+  struct Fts3auxColstats {
+    sqlite3_int64 nDoc;           /* 'documents' values for current csr row */
+    sqlite3_int64 nOcc;           /* 'occurrences' values for current csr row */
+  } *aStat;
+};
+
+/*
+** Schema of the terms table.
+*/
+#define FTS3_AUX_SCHEMA \
+  "CREATE TABLE x(term, col, documents, occurrences, languageid HIDDEN)"
+
+/*
+** This function does all the work for both the xConnect and xCreate methods.
+** These tables have no persistent representation of their own, so xConnect
+** and xCreate are identical operations.
+*/
+static int fts3auxConnectMethod(
+  sqlite3 *db,                    /* Database connection */
+  void *pUnused,                  /* Unused */
+  int argc,                       /* Number of elements in argv array */
+  const char * const *argv,       /* xCreate/xConnect argument array */
+  sqlite3_vtab **ppVtab,          /* OUT: New sqlite3_vtab object */
+  char **pzErr                    /* OUT: sqlite3_malloc'd error message */
+){
+  char const *zDb;                /* Name of database (e.g. "main") */
+  char const *zFts3;              /* Name of fts3 table */
+  int nDb;                        /* Result of strlen(zDb) */
+  int nFts3;                      /* Result of strlen(zFts3) */
+  int nByte;                      /* Bytes of space to allocate here */
+  int rc;                         /* value returned by declare_vtab() */
+  Fts3auxTable *p;                /* Virtual table object to return */
+
+  UNUSED_PARAMETER(pUnused);
+
+  /* The user should invoke this in one of two forms:
+  **
+  **     CREATE VIRTUAL TABLE xxx USING fts4aux(fts4-table);
+  **     CREATE VIRTUAL TABLE xxx USING fts4aux(fts4-table-db, fts4-table);
+  */
+  if( argc!=4 && argc!=5 ) goto bad_args;
+
+  zDb = argv[1]; 
+  nDb = (int)strlen(zDb);
+  if( argc==5 ){
+    if( nDb==4 && 0==sqlite3_strnicmp("temp", zDb, 4) ){
+      zDb = argv[3]; 
+      nDb = (int)strlen(zDb);
+      zFts3 = argv[4];
+    }else{
+      goto bad_args;
+    }
+  }else{
+    zFts3 = argv[3];
+  }
+  nFts3 = (int)strlen(zFts3);
+
+  rc = sqlite3_declare_vtab(db, FTS3_AUX_SCHEMA);
+  if( rc!=SQLITE_OK ) return rc;
+
+  nByte = sizeof(Fts3auxTable) + sizeof(Fts3Table) + nDb + nFts3 + 2;
+  p = (Fts3auxTable *)sqlite3_malloc(nByte);
+  if( !p ) return SQLITE_NOMEM;
+  memset(p, 0, nByte);
+
+  p->pFts3Tab = (Fts3Table *)&p[1];
+  p->pFts3Tab->zDb = (char *)&p->pFts3Tab[1];
+  p->pFts3Tab->zName = &p->pFts3Tab->zDb[nDb+1];
+  p->pFts3Tab->db = db;
+  p->pFts3Tab->nIndex = 1;
+
+  memcpy((char *)p->pFts3Tab->zDb, zDb, nDb);
+  memcpy((char *)p->pFts3Tab->zName, zFts3, nFts3);
+  sqlite3Fts3Dequote((char *)p->pFts3Tab->zName);
+
+  *ppVtab = (sqlite3_vtab *)p;
+  return SQLITE_OK;
+
+ bad_args:
+  sqlite3Fts3ErrMsg(pzErr, "invalid arguments to fts4aux constructor");
+  return SQLITE_ERROR;
+}
+
+/*
+** This function does the work for both the xDisconnect and xDestroy methods.
+** These tables have no persistent representation of their own, so xDisconnect
+** and xDestroy are identical operations.
+*/
+static int fts3auxDisconnectMethod(sqlite3_vtab *pVtab){
+  Fts3auxTable *p = (Fts3auxTable *)pVtab;
+  Fts3Table *pFts3 = p->pFts3Tab;
+  int i;
+
+  /* Free any prepared statements held */
+  for(i=0; i<SizeofArray(pFts3->aStmt); i++){
+    sqlite3_finalize(pFts3->aStmt[i]);
+  }
+  sqlite3_free(pFts3->zSegmentsTbl);
+  sqlite3_free(p);
+  return SQLITE_OK;
+}
+
+#define FTS4AUX_EQ_CONSTRAINT 1
+#define FTS4AUX_GE_CONSTRAINT 2
+#define FTS4AUX_LE_CONSTRAINT 4
+
+/*
+** xBestIndex - Analyze a WHERE and ORDER BY clause.
+*/
+static int fts3auxBestIndexMethod(
+  sqlite3_vtab *pVTab, 
+  sqlite3_index_info *pInfo
+){
+  int i;
+  int iEq = -1;
+  int iGe = -1;
+  int iLe = -1;
+  int iLangid = -1;
+  int iNext = 1;                  /* Next free argvIndex value */
+
+  UNUSED_PARAMETER(pVTab);
+
+  /* This vtab delivers always results in "ORDER BY term ASC" order. */
+  if( pInfo->nOrderBy==1 
+   && pInfo->aOrderBy[0].iColumn==0 
+   && pInfo->aOrderBy[0].desc==0
+  ){
+    pInfo->orderByConsumed = 1;
+  }
+
+  /* Search for equality and range constraints on the "term" column. 
+  ** And equality constraints on the hidden "languageid" column. */
+  for(i=0; i<pInfo->nConstraint; i++){
+    if( pInfo->aConstraint[i].usable ){
+      int op = pInfo->aConstraint[i].op;
+      int iCol = pInfo->aConstraint[i].iColumn;
+
+      if( iCol==0 ){
+        if( op==SQLITE_INDEX_CONSTRAINT_EQ ) iEq = i;
+        if( op==SQLITE_INDEX_CONSTRAINT_LT ) iLe = i;
+        if( op==SQLITE_INDEX_CONSTRAINT_LE ) iLe = i;
+        if( op==SQLITE_INDEX_CONSTRAINT_GT ) iGe = i;
+        if( op==SQLITE_INDEX_CONSTRAINT_GE ) iGe = i;
+      }
+      if( iCol==4 ){
+        if( op==SQLITE_INDEX_CONSTRAINT_EQ ) iLangid = i;
+      }
+    }
+  }
+
+  if( iEq>=0 ){
+    pInfo->idxNum = FTS4AUX_EQ_CONSTRAINT;
+    pInfo->aConstraintUsage[iEq].argvIndex = iNext++;
+    pInfo->estimatedCost = 5;
+  }else{
+    pInfo->idxNum = 0;
+    pInfo->estimatedCost = 20000;
+    if( iGe>=0 ){
+      pInfo->idxNum += FTS4AUX_GE_CONSTRAINT;
+      pInfo->aConstraintUsage[iGe].argvIndex = iNext++;
+      pInfo->estimatedCost /= 2;
+    }
+    if( iLe>=0 ){
+      pInfo->idxNum += FTS4AUX_LE_CONSTRAINT;
+      pInfo->aConstraintUsage[iLe].argvIndex = iNext++;
+      pInfo->estimatedCost /= 2;
+    }
+  }
+  if( iLangid>=0 ){
+    pInfo->aConstraintUsage[iLangid].argvIndex = iNext++;
+    pInfo->estimatedCost--;
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** xOpen - Open a cursor.
+*/
+static int fts3auxOpenMethod(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCsr){
+  Fts3auxCursor *pCsr;            /* Pointer to cursor object to return */
+
+  UNUSED_PARAMETER(pVTab);
+
+  pCsr = (Fts3auxCursor *)sqlite3_malloc(sizeof(Fts3auxCursor));
+  if( !pCsr ) return SQLITE_NOMEM;
+  memset(pCsr, 0, sizeof(Fts3auxCursor));
+
+  *ppCsr = (sqlite3_vtab_cursor *)pCsr;
+  return SQLITE_OK;
+}
+
+/*
+** xClose - Close a cursor.
+*/
+static int fts3auxCloseMethod(sqlite3_vtab_cursor *pCursor){
+  Fts3Table *pFts3 = ((Fts3auxTable *)pCursor->pVtab)->pFts3Tab;
+  Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor;
+
+  sqlite3Fts3SegmentsClose(pFts3);
+  sqlite3Fts3SegReaderFinish(&pCsr->csr);
+  sqlite3_free((void *)pCsr->filter.zTerm);
+  sqlite3_free(pCsr->zStop);
+  sqlite3_free(pCsr->aStat);
+  sqlite3_free(pCsr);
+  return SQLITE_OK;
+}
+
+static int fts3auxGrowStatArray(Fts3auxCursor *pCsr, int nSize){
+  if( nSize>pCsr->nStat ){
+    struct Fts3auxColstats *aNew;
+    aNew = (struct Fts3auxColstats *)sqlite3_realloc(pCsr->aStat, 
+        sizeof(struct Fts3auxColstats) * nSize
+    );
+    if( aNew==0 ) return SQLITE_NOMEM;
+    memset(&aNew[pCsr->nStat], 0, 
+        sizeof(struct Fts3auxColstats) * (nSize - pCsr->nStat)
+    );
+    pCsr->aStat = aNew;
+    pCsr->nStat = nSize;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** xNext - Advance the cursor to the next row, if any.
+*/
+static int fts3auxNextMethod(sqlite3_vtab_cursor *pCursor){
+  Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor;
+  Fts3Table *pFts3 = ((Fts3auxTable *)pCursor->pVtab)->pFts3Tab;
+  int rc;
+
+  /* Increment our pretend rowid value. */
+  pCsr->iRowid++;
+
+  for(pCsr->iCol++; pCsr->iCol<pCsr->nStat; pCsr->iCol++){
+    if( pCsr->aStat[pCsr->iCol].nDoc>0 ) return SQLITE_OK;
+  }
+
+  rc = sqlite3Fts3SegReaderStep(pFts3, &pCsr->csr);
+  if( rc==SQLITE_ROW ){
+    int i = 0;
+    int nDoclist = pCsr->csr.nDoclist;
+    char *aDoclist = pCsr->csr.aDoclist;
+    int iCol;
+
+    int eState = 0;
+
+    if( pCsr->zStop ){
+      int n = (pCsr->nStop<pCsr->csr.nTerm) ? pCsr->nStop : pCsr->csr.nTerm;
+      int mc = memcmp(pCsr->zStop, pCsr->csr.zTerm, n);
+      if( mc<0 || (mc==0 && pCsr->csr.nTerm>pCsr->nStop) ){
+        pCsr->isEof = 1;
+        return SQLITE_OK;
+      }
+    }
+
+    if( fts3auxGrowStatArray(pCsr, 2) ) return SQLITE_NOMEM;
+    memset(pCsr->aStat, 0, sizeof(struct Fts3auxColstats) * pCsr->nStat);
+    iCol = 0;
+
+    while( i<nDoclist ){
+      sqlite3_int64 v = 0;
+
+      i += sqlite3Fts3GetVarint(&aDoclist[i], &v);
+      switch( eState ){
+        /* State 0. In this state the integer just read was a docid. */
+        case 0:
+          pCsr->aStat[0].nDoc++;
+          eState = 1;
+          iCol = 0;
+          break;
+
+        /* State 1. In this state we are expecting either a 1, indicating
+        ** that the following integer will be a column number, or the
+        ** start of a position list for column 0.  
+        ** 
+        ** The only difference between state 1 and state 2 is that if the
+        ** integer encountered in state 1 is not 0 or 1, then we need to
+        ** increment the column 0 "nDoc" count for this term.
+        */
+        case 1:
+          assert( iCol==0 );
+          if( v>1 ){
+            pCsr->aStat[1].nDoc++;
+          }
+          eState = 2;
+          /* fall through */
+
+        case 2:
+          if( v==0 ){       /* 0x00. Next integer will be a docid. */
+            eState = 0;
+          }else if( v==1 ){ /* 0x01. Next integer will be a column number. */
+            eState = 3;
+          }else{            /* 2 or greater. A position. */
+            pCsr->aStat[iCol+1].nOcc++;
+            pCsr->aStat[0].nOcc++;
+          }
+          break;
+
+        /* State 3. The integer just read is a column number. */
+        default: assert( eState==3 );
+          iCol = (int)v;
+          if( fts3auxGrowStatArray(pCsr, iCol+2) ) return SQLITE_NOMEM;
+          pCsr->aStat[iCol+1].nDoc++;
+          eState = 2;
+          break;
+      }
+    }
+
+    pCsr->iCol = 0;
+    rc = SQLITE_OK;
+  }else{
+    pCsr->isEof = 1;
+  }
+  return rc;
+}
+
+/*
+** xFilter - Initialize a cursor to point at the start of its data.
+*/
+static int fts3auxFilterMethod(
+  sqlite3_vtab_cursor *pCursor,   /* The cursor used for this query */
+  int idxNum,                     /* Strategy index */
+  const char *idxStr,             /* Unused */
+  int nVal,                       /* Number of elements in apVal */
+  sqlite3_value **apVal           /* Arguments for the indexing scheme */
+){
+  Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor;
+  Fts3Table *pFts3 = ((Fts3auxTable *)pCursor->pVtab)->pFts3Tab;
+  int rc;
+  int isScan = 0;
+  int iLangVal = 0;               /* Language id to query */
+
+  int iEq = -1;                   /* Index of term=? value in apVal */
+  int iGe = -1;                   /* Index of term>=? value in apVal */
+  int iLe = -1;                   /* Index of term<=? value in apVal */
+  int iLangid = -1;               /* Index of languageid=? value in apVal */
+  int iNext = 0;
+
+  UNUSED_PARAMETER(nVal);
+  UNUSED_PARAMETER(idxStr);
+
+  assert( idxStr==0 );
+  assert( idxNum==FTS4AUX_EQ_CONSTRAINT || idxNum==0
+       || idxNum==FTS4AUX_LE_CONSTRAINT || idxNum==FTS4AUX_GE_CONSTRAINT
+       || idxNum==(FTS4AUX_LE_CONSTRAINT|FTS4AUX_GE_CONSTRAINT)
+  );
+
+  if( idxNum==FTS4AUX_EQ_CONSTRAINT ){
+    iEq = iNext++;
+  }else{
+    isScan = 1;
+    if( idxNum & FTS4AUX_GE_CONSTRAINT ){
+      iGe = iNext++;
+    }
+    if( idxNum & FTS4AUX_LE_CONSTRAINT ){
+      iLe = iNext++;
+    }
+  }
+  if( iNext<nVal ){
+    iLangid = iNext++;
+  }
+
+  /* In case this cursor is being reused, close and zero it. */
+  testcase(pCsr->filter.zTerm);
+  sqlite3Fts3SegReaderFinish(&pCsr->csr);
+  sqlite3_free((void *)pCsr->filter.zTerm);
+  sqlite3_free(pCsr->aStat);
+  memset(&pCsr->csr, 0, ((u8*)&pCsr[1]) - (u8*)&pCsr->csr);
+
+  pCsr->filter.flags = FTS3_SEGMENT_REQUIRE_POS|FTS3_SEGMENT_IGNORE_EMPTY;
+  if( isScan ) pCsr->filter.flags |= FTS3_SEGMENT_SCAN;
+
+  if( iEq>=0 || iGe>=0 ){
+    const unsigned char *zStr = sqlite3_value_text(apVal[0]);
+    assert( (iEq==0 && iGe==-1) || (iEq==-1 && iGe==0) );
+    if( zStr ){
+      pCsr->filter.zTerm = sqlite3_mprintf("%s", zStr);
+      pCsr->filter.nTerm = sqlite3_value_bytes(apVal[0]);
+      if( pCsr->filter.zTerm==0 ) return SQLITE_NOMEM;
+    }
+  }
+
+  if( iLe>=0 ){
+    pCsr->zStop = sqlite3_mprintf("%s", sqlite3_value_text(apVal[iLe]));
+    pCsr->nStop = sqlite3_value_bytes(apVal[iLe]);
+    if( pCsr->zStop==0 ) return SQLITE_NOMEM;
+  }
+  
+  if( iLangid>=0 ){
+    iLangVal = sqlite3_value_int(apVal[iLangid]);
+
+    /* If the user specified a negative value for the languageid, use zero
+    ** instead. This works, as the "languageid=?" constraint will also
+    ** be tested by the VDBE layer. The test will always be false (since
+    ** this module will not return a row with a negative languageid), and
+    ** so the overall query will return zero rows.  */
+    if( iLangVal<0 ) iLangVal = 0;
+  }
+  pCsr->iLangid = iLangVal;
+
+  rc = sqlite3Fts3SegReaderCursor(pFts3, iLangVal, 0, FTS3_SEGCURSOR_ALL,
+      pCsr->filter.zTerm, pCsr->filter.nTerm, 0, isScan, &pCsr->csr
+  );
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts3SegReaderStart(pFts3, &pCsr->csr, &pCsr->filter);
+  }
+
+  if( rc==SQLITE_OK ) rc = fts3auxNextMethod(pCursor);
+  return rc;
+}
+
+/*
+** xEof - Return true if the cursor is at EOF, or false otherwise.
+*/
+static int fts3auxEofMethod(sqlite3_vtab_cursor *pCursor){
+  Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor;
+  return pCsr->isEof;
+}
+
+/*
+** xColumn - Return a column value.
+*/
+static int fts3auxColumnMethod(
+  sqlite3_vtab_cursor *pCursor,   /* Cursor to retrieve value from */
+  sqlite3_context *pCtx,          /* Context for sqlite3_result_xxx() calls */
+  int iCol                        /* Index of column to read value from */
+){
+  Fts3auxCursor *p = (Fts3auxCursor *)pCursor;
+
+  assert( p->isEof==0 );
+  switch( iCol ){
+    case 0: /* term */
+      sqlite3_result_text(pCtx, p->csr.zTerm, p->csr.nTerm, SQLITE_TRANSIENT);
+      break;
+
+    case 1: /* col */
+      if( p->iCol ){
+        sqlite3_result_int(pCtx, p->iCol-1);
+      }else{
+        sqlite3_result_text(pCtx, "*", -1, SQLITE_STATIC);
+      }
+      break;
+
+    case 2: /* documents */
+      sqlite3_result_int64(pCtx, p->aStat[p->iCol].nDoc);
+      break;
+
+    case 3: /* occurrences */
+      sqlite3_result_int64(pCtx, p->aStat[p->iCol].nOcc);
+      break;
+
+    default: /* languageid */
+      assert( iCol==4 );
+      sqlite3_result_int(pCtx, p->iLangid);
+      break;
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** xRowid - Return the current rowid for the cursor.
+*/
+static int fts3auxRowidMethod(
+  sqlite3_vtab_cursor *pCursor,   /* Cursor to retrieve value from */
+  sqlite_int64 *pRowid            /* OUT: Rowid value */
+){
+  Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor;
+  *pRowid = pCsr->iRowid;
+  return SQLITE_OK;
+}
+
+/*
+** Register the fts3aux module with database connection db. Return SQLITE_OK
+** if successful or an error code if sqlite3_create_module() fails.
+*/
+SQLITE_PRIVATE int sqlite3Fts3InitAux(sqlite3 *db){
+  static const sqlite3_module fts3aux_module = {
+     0,                           /* iVersion      */
+     fts3auxConnectMethod,        /* xCreate       */
+     fts3auxConnectMethod,        /* xConnect      */
+     fts3auxBestIndexMethod,      /* xBestIndex    */
+     fts3auxDisconnectMethod,     /* xDisconnect   */
+     fts3auxDisconnectMethod,     /* xDestroy      */
+     fts3auxOpenMethod,           /* xOpen         */
+     fts3auxCloseMethod,          /* xClose        */
+     fts3auxFilterMethod,         /* xFilter       */
+     fts3auxNextMethod,           /* xNext         */
+     fts3auxEofMethod,            /* xEof          */
+     fts3auxColumnMethod,         /* xColumn       */
+     fts3auxRowidMethod,          /* xRowid        */
+     0,                           /* xUpdate       */
+     0,                           /* xBegin        */
+     0,                           /* xSync         */
+     0,                           /* xCommit       */
+     0,                           /* xRollback     */
+     0,                           /* xFindFunction */
+     0,                           /* xRename       */
+     0,                           /* xSavepoint    */
+     0,                           /* xRelease      */
+     0                            /* xRollbackTo   */
+  };
+  int rc;                         /* Return code */
+
+  rc = sqlite3_create_module(db, "fts4aux", &fts3aux_module, 0);
+  return rc;
+}
+
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */
+
+/************** End of fts3_aux.c ********************************************/
+/************** Begin file fts3_expr.c ***************************************/
+/*
+** 2008 Nov 28
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This module contains code that implements a parser for fts3 query strings
+** (the right-hand argument to the MATCH operator). Because the supported 
+** syntax is relatively simple, the whole tokenizer/parser system is
+** hand-coded. 
+*/
+/* #include "fts3Int.h" */
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
+
+/*
+** By default, this module parses the legacy syntax that has been 
+** traditionally used by fts3. Or, if SQLITE_ENABLE_FTS3_PARENTHESIS
+** is defined, then it uses the new syntax. The differences between
+** the new and the old syntaxes are:
+**
+**  a) The new syntax supports parenthesis. The old does not.
+**
+**  b) The new syntax supports the AND and NOT operators. The old does not.
+**
+**  c) The old syntax supports the "-" token qualifier. This is not 
+**     supported by the new syntax (it is replaced by the NOT operator).
+**
+**  d) When using the old syntax, the OR operator has a greater precedence
+**     than an implicit AND. When using the new, both implicity and explicit
+**     AND operators have a higher precedence than OR.
+**
+** If compiled with SQLITE_TEST defined, then this module exports the
+** symbol "int sqlite3_fts3_enable_parentheses". Setting this variable
+** to zero causes the module to use the old syntax. If it is set to 
+** non-zero the new syntax is activated. This is so both syntaxes can
+** be tested using a single build of testfixture.
+**
+** The following describes the syntax supported by the fts3 MATCH
+** operator in a similar format to that used by the lemon parser
+** generator. This module does not use actually lemon, it uses a
+** custom parser.
+**
+**   query ::= andexpr (OR andexpr)*.
+**
+**   andexpr ::= notexpr (AND? notexpr)*.
+**
+**   notexpr ::= nearexpr (NOT nearexpr|-TOKEN)*.
+**   notexpr ::= LP query RP.
+**
+**   nearexpr ::= phrase (NEAR distance_opt nearexpr)*.
+**
+**   distance_opt ::= .
+**   distance_opt ::= / INTEGER.
+**
+**   phrase ::= TOKEN.
+**   phrase ::= COLUMN:TOKEN.
+**   phrase ::= "TOKEN TOKEN TOKEN...".
+*/
+
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_fts3_enable_parentheses = 0;
+#else
+# ifdef SQLITE_ENABLE_FTS3_PARENTHESIS 
+#  define sqlite3_fts3_enable_parentheses 1
+# else
+#  define sqlite3_fts3_enable_parentheses 0
+# endif
+#endif
+
+/*
+** Default span for NEAR operators.
+*/
+#define SQLITE_FTS3_DEFAULT_NEAR_PARAM 10
+
+/* #include <string.h> */
+/* #include <assert.h> */
+
+/*
+** isNot:
+**   This variable is used by function getNextNode(). When getNextNode() is
+**   called, it sets ParseContext.isNot to true if the 'next node' is a 
+**   FTSQUERY_PHRASE with a unary "-" attached to it. i.e. "mysql" in the
+**   FTS3 query "sqlite -mysql". Otherwise, ParseContext.isNot is set to
+**   zero.
+*/
+typedef struct ParseContext ParseContext;
+struct ParseContext {
+  sqlite3_tokenizer *pTokenizer;      /* Tokenizer module */
+  int iLangid;                        /* Language id used with tokenizer */
+  const char **azCol;                 /* Array of column names for fts3 table */
+  int bFts4;                          /* True to allow FTS4-only syntax */
+  int nCol;                           /* Number of entries in azCol[] */
+  int iDefaultCol;                    /* Default column to query */
+  int isNot;                          /* True if getNextNode() sees a unary - */
+  sqlite3_context *pCtx;              /* Write error message here */
+  int nNest;                          /* Number of nested brackets */
+};
+
+/*
+** This function is equivalent to the standard isspace() function. 
+**
+** The standard isspace() can be awkward to use safely, because although it
+** is defined to accept an argument of type int, its behavior when passed
+** an integer that falls outside of the range of the unsigned char type
+** is undefined (and sometimes, "undefined" means segfault). This wrapper
+** is defined to accept an argument of type char, and always returns 0 for
+** any values that fall outside of the range of the unsigned char type (i.e.
+** negative values).
+*/
+static int fts3isspace(char c){
+  return c==' ' || c=='\t' || c=='\n' || c=='\r' || c=='\v' || c=='\f';
+}
+
+/*
+** Allocate nByte bytes of memory using sqlite3_malloc(). If successful,
+** zero the memory before returning a pointer to it. If unsuccessful, 
+** return NULL.
+*/
+static void *fts3MallocZero(int nByte){
+  void *pRet = sqlite3_malloc(nByte);
+  if( pRet ) memset(pRet, 0, nByte);
+  return pRet;
+}
+
+SQLITE_PRIVATE int sqlite3Fts3OpenTokenizer(
+  sqlite3_tokenizer *pTokenizer,
+  int iLangid,
+  const char *z,
+  int n,
+  sqlite3_tokenizer_cursor **ppCsr
+){
+  sqlite3_tokenizer_module const *pModule = pTokenizer->pModule;
+  sqlite3_tokenizer_cursor *pCsr = 0;
+  int rc;
+
+  rc = pModule->xOpen(pTokenizer, z, n, &pCsr);
+  assert( rc==SQLITE_OK || pCsr==0 );
+  if( rc==SQLITE_OK ){
+    pCsr->pTokenizer = pTokenizer;
+    if( pModule->iVersion>=1 ){
+      rc = pModule->xLanguageid(pCsr, iLangid);
+      if( rc!=SQLITE_OK ){
+        pModule->xClose(pCsr);
+        pCsr = 0;
+      }
+    }
+  }
+  *ppCsr = pCsr;
+  return rc;
+}
+
+/*
+** Function getNextNode(), which is called by fts3ExprParse(), may itself
+** call fts3ExprParse(). So this forward declaration is required.
+*/
+static int fts3ExprParse(ParseContext *, const char *, int, Fts3Expr **, int *);
+
+/*
+** Extract the next token from buffer z (length n) using the tokenizer
+** and other information (column names etc.) in pParse. Create an Fts3Expr
+** structure of type FTSQUERY_PHRASE containing a phrase consisting of this
+** single token and set *ppExpr to point to it. If the end of the buffer is
+** reached before a token is found, set *ppExpr to zero. It is the
+** responsibility of the caller to eventually deallocate the allocated 
+** Fts3Expr structure (if any) by passing it to sqlite3_free().
+**
+** Return SQLITE_OK if successful, or SQLITE_NOMEM if a memory allocation
+** fails.
+*/
+static int getNextToken(
+  ParseContext *pParse,                   /* fts3 query parse context */
+  int iCol,                               /* Value for Fts3Phrase.iColumn */
+  const char *z, int n,                   /* Input string */
+  Fts3Expr **ppExpr,                      /* OUT: expression */
+  int *pnConsumed                         /* OUT: Number of bytes consumed */
+){
+  sqlite3_tokenizer *pTokenizer = pParse->pTokenizer;
+  sqlite3_tokenizer_module const *pModule = pTokenizer->pModule;
+  int rc;
+  sqlite3_tokenizer_cursor *pCursor;
+  Fts3Expr *pRet = 0;
+  int i = 0;
+
+  /* Set variable i to the maximum number of bytes of input to tokenize. */
+  for(i=0; i<n; i++){
+    if( sqlite3_fts3_enable_parentheses && (z[i]=='(' || z[i]==')') ) break;
+    if( z[i]=='"' ) break;
+  }
+
+  *pnConsumed = i;
+  rc = sqlite3Fts3OpenTokenizer(pTokenizer, pParse->iLangid, z, i, &pCursor);
+  if( rc==SQLITE_OK ){
+    const char *zToken;
+    int nToken = 0, iStart = 0, iEnd = 0, iPosition = 0;
+    int nByte;                               /* total space to allocate */
+
+    rc = pModule->xNext(pCursor, &zToken, &nToken, &iStart, &iEnd, &iPosition);
+    if( rc==SQLITE_OK ){
+      nByte = sizeof(Fts3Expr) + sizeof(Fts3Phrase) + nToken;
+      pRet = (Fts3Expr *)fts3MallocZero(nByte);
+      if( !pRet ){
+        rc = SQLITE_NOMEM;
+      }else{
+        pRet->eType = FTSQUERY_PHRASE;
+        pRet->pPhrase = (Fts3Phrase *)&pRet[1];
+        pRet->pPhrase->nToken = 1;
+        pRet->pPhrase->iColumn = iCol;
+        pRet->pPhrase->aToken[0].n = nToken;
+        pRet->pPhrase->aToken[0].z = (char *)&pRet->pPhrase[1];
+        memcpy(pRet->pPhrase->aToken[0].z, zToken, nToken);
+
+        if( iEnd<n && z[iEnd]=='*' ){
+          pRet->pPhrase->aToken[0].isPrefix = 1;
+          iEnd++;
+        }
+
+        while( 1 ){
+          if( !sqlite3_fts3_enable_parentheses 
+           && iStart>0 && z[iStart-1]=='-' 
+          ){
+            pParse->isNot = 1;
+            iStart--;
+          }else if( pParse->bFts4 && iStart>0 && z[iStart-1]=='^' ){
+            pRet->pPhrase->aToken[0].bFirst = 1;
+            iStart--;
+          }else{
+            break;
+          }
+        }
+
+      }
+      *pnConsumed = iEnd;
+    }else if( i && rc==SQLITE_DONE ){
+      rc = SQLITE_OK;
+    }
+
+    pModule->xClose(pCursor);
+  }
+  
+  *ppExpr = pRet;
+  return rc;
+}
+
+
+/*
+** Enlarge a memory allocation.  If an out-of-memory allocation occurs,
+** then free the old allocation.
+*/
+static void *fts3ReallocOrFree(void *pOrig, int nNew){
+  void *pRet = sqlite3_realloc(pOrig, nNew);
+  if( !pRet ){
+    sqlite3_free(pOrig);
+  }
+  return pRet;
+}
+
+/*
+** Buffer zInput, length nInput, contains the contents of a quoted string
+** that appeared as part of an fts3 query expression. Neither quote character
+** is included in the buffer. This function attempts to tokenize the entire
+** input buffer and create an Fts3Expr structure of type FTSQUERY_PHRASE 
+** containing the results.
+**
+** If successful, SQLITE_OK is returned and *ppExpr set to point at the
+** allocated Fts3Expr structure. Otherwise, either SQLITE_NOMEM (out of memory
+** error) or SQLITE_ERROR (tokenization error) is returned and *ppExpr set
+** to 0.
+*/
+static int getNextString(
+  ParseContext *pParse,                   /* fts3 query parse context */
+  const char *zInput, int nInput,         /* Input string */
+  Fts3Expr **ppExpr                       /* OUT: expression */
+){
+  sqlite3_tokenizer *pTokenizer = pParse->pTokenizer;
+  sqlite3_tokenizer_module const *pModule = pTokenizer->pModule;
+  int rc;
+  Fts3Expr *p = 0;
+  sqlite3_tokenizer_cursor *pCursor = 0;
+  char *zTemp = 0;
+  int nTemp = 0;
+
+  const int nSpace = sizeof(Fts3Expr) + sizeof(Fts3Phrase);
+  int nToken = 0;
+
+  /* The final Fts3Expr data structure, including the Fts3Phrase,
+  ** Fts3PhraseToken structures token buffers are all stored as a single 
+  ** allocation so that the expression can be freed with a single call to
+  ** sqlite3_free(). Setting this up requires a two pass approach.
+  **
+  ** The first pass, in the block below, uses a tokenizer cursor to iterate
+  ** through the tokens in the expression. This pass uses fts3ReallocOrFree()
+  ** to assemble data in two dynamic buffers:
+  **
+  **   Buffer p: Points to the Fts3Expr structure, followed by the Fts3Phrase
+  **             structure, followed by the array of Fts3PhraseToken 
+  **             structures. This pass only populates the Fts3PhraseToken array.
+  **
+  **   Buffer zTemp: Contains copies of all tokens.
+  **
+  ** The second pass, in the block that begins "if( rc==SQLITE_DONE )" below,
+  ** appends buffer zTemp to buffer p, and fills in the Fts3Expr and Fts3Phrase
+  ** structures.
+  */
+  rc = sqlite3Fts3OpenTokenizer(
+      pTokenizer, pParse->iLangid, zInput, nInput, &pCursor);
+  if( rc==SQLITE_OK ){
+    int ii;
+    for(ii=0; rc==SQLITE_OK; ii++){
+      const char *zByte;
+      int nByte = 0, iBegin = 0, iEnd = 0, iPos = 0;
+      rc = pModule->xNext(pCursor, &zByte, &nByte, &iBegin, &iEnd, &iPos);
+      if( rc==SQLITE_OK ){
+        Fts3PhraseToken *pToken;
+
+        p = fts3ReallocOrFree(p, nSpace + ii*sizeof(Fts3PhraseToken));
+        if( !p ) goto no_mem;
+
+        zTemp = fts3ReallocOrFree(zTemp, nTemp + nByte);
+        if( !zTemp ) goto no_mem;
+
+        assert( nToken==ii );
+        pToken = &((Fts3Phrase *)(&p[1]))->aToken[ii];
+        memset(pToken, 0, sizeof(Fts3PhraseToken));
+
+        memcpy(&zTemp[nTemp], zByte, nByte);
+        nTemp += nByte;
+
+        pToken->n = nByte;
+        pToken->isPrefix = (iEnd<nInput && zInput[iEnd]=='*');
+        pToken->bFirst = (iBegin>0 && zInput[iBegin-1]=='^');
+        nToken = ii+1;
+      }
+    }
+
+    pModule->xClose(pCursor);
+    pCursor = 0;
+  }
+
+  if( rc==SQLITE_DONE ){
+    int jj;
+    char *zBuf = 0;
+
+    p = fts3ReallocOrFree(p, nSpace + nToken*sizeof(Fts3PhraseToken) + nTemp);
+    if( !p ) goto no_mem;
+    memset(p, 0, (char *)&(((Fts3Phrase *)&p[1])->aToken[0])-(char *)p);
+    p->eType = FTSQUERY_PHRASE;
+    p->pPhrase = (Fts3Phrase *)&p[1];
+    p->pPhrase->iColumn = pParse->iDefaultCol;
+    p->pPhrase->nToken = nToken;
+
+    zBuf = (char *)&p->pPhrase->aToken[nToken];
+    if( zTemp ){
+      memcpy(zBuf, zTemp, nTemp);
+      sqlite3_free(zTemp);
+    }else{
+      assert( nTemp==0 );
+    }
+
+    for(jj=0; jj<p->pPhrase->nToken; jj++){
+      p->pPhrase->aToken[jj].z = zBuf;
+      zBuf += p->pPhrase->aToken[jj].n;
+    }
+    rc = SQLITE_OK;
+  }
+
+  *ppExpr = p;
+  return rc;
+no_mem:
+
+  if( pCursor ){
+    pModule->xClose(pCursor);
+  }
+  sqlite3_free(zTemp);
+  sqlite3_free(p);
+  *ppExpr = 0;
+  return SQLITE_NOMEM;
+}
+
+/*
+** The output variable *ppExpr is populated with an allocated Fts3Expr 
+** structure, or set to 0 if the end of the input buffer is reached.
+**
+** Returns an SQLite error code. SQLITE_OK if everything works, SQLITE_NOMEM
+** if a malloc failure occurs, or SQLITE_ERROR if a parse error is encountered.
+** If SQLITE_ERROR is returned, pContext is populated with an error message.
+*/
+static int getNextNode(
+  ParseContext *pParse,                   /* fts3 query parse context */
+  const char *z, int n,                   /* Input string */
+  Fts3Expr **ppExpr,                      /* OUT: expression */
+  int *pnConsumed                         /* OUT: Number of bytes consumed */
+){
+  static const struct Fts3Keyword {
+    char *z;                              /* Keyword text */
+    unsigned char n;                      /* Length of the keyword */
+    unsigned char parenOnly;              /* Only valid in paren mode */
+    unsigned char eType;                  /* Keyword code */
+  } aKeyword[] = {
+    { "OR" ,  2, 0, FTSQUERY_OR   },
+    { "AND",  3, 1, FTSQUERY_AND  },
+    { "NOT",  3, 1, FTSQUERY_NOT  },
+    { "NEAR", 4, 0, FTSQUERY_NEAR }
+  };
+  int ii;
+  int iCol;
+  int iColLen;
+  int rc;
+  Fts3Expr *pRet = 0;
+
+  const char *zInput = z;
+  int nInput = n;
+
+  pParse->isNot = 0;
+
+  /* Skip over any whitespace before checking for a keyword, an open or
+  ** close bracket, or a quoted string. 
+  */
+  while( nInput>0 && fts3isspace(*zInput) ){
+    nInput--;
+    zInput++;
+  }
+  if( nInput==0 ){
+    return SQLITE_DONE;
+  }
+
+  /* See if we are dealing with a keyword. */
+  for(ii=0; ii<(int)(sizeof(aKeyword)/sizeof(struct Fts3Keyword)); ii++){
+    const struct Fts3Keyword *pKey = &aKeyword[ii];
+
+    if( (pKey->parenOnly & ~sqlite3_fts3_enable_parentheses)!=0 ){
+      continue;
+    }
+
+    if( nInput>=pKey->n && 0==memcmp(zInput, pKey->z, pKey->n) ){
+      int nNear = SQLITE_FTS3_DEFAULT_NEAR_PARAM;
+      int nKey = pKey->n;
+      char cNext;
+
+      /* If this is a "NEAR" keyword, check for an explicit nearness. */
+      if( pKey->eType==FTSQUERY_NEAR ){
+        assert( nKey==4 );
+        if( zInput[4]=='/' && zInput[5]>='0' && zInput[5]<='9' ){
+          nNear = 0;
+          for(nKey=5; zInput[nKey]>='0' && zInput[nKey]<='9'; nKey++){
+            nNear = nNear * 10 + (zInput[nKey] - '0');
+          }
+        }
+      }
+
+      /* At this point this is probably a keyword. But for that to be true,
+      ** the next byte must contain either whitespace, an open or close
+      ** parenthesis, a quote character, or EOF. 
+      */
+      cNext = zInput[nKey];
+      if( fts3isspace(cNext) 
+       || cNext=='"' || cNext=='(' || cNext==')' || cNext==0
+      ){
+        pRet = (Fts3Expr *)fts3MallocZero(sizeof(Fts3Expr));
+        if( !pRet ){
+          return SQLITE_NOMEM;
+        }
+        pRet->eType = pKey->eType;
+        pRet->nNear = nNear;
+        *ppExpr = pRet;
+        *pnConsumed = (int)((zInput - z) + nKey);
+        return SQLITE_OK;
+      }
+
+      /* Turns out that wasn't a keyword after all. This happens if the
+      ** user has supplied a token such as "ORacle". Continue.
+      */
+    }
+  }
+
+  /* See if we are dealing with a quoted phrase. If this is the case, then
+  ** search for the closing quote and pass the whole string to getNextString()
+  ** for processing. This is easy to do, as fts3 has no syntax for escaping
+  ** a quote character embedded in a string.
+  */
+  if( *zInput=='"' ){
+    for(ii=1; ii<nInput && zInput[ii]!='"'; ii++);
+    *pnConsumed = (int)((zInput - z) + ii + 1);
+    if( ii==nInput ){
+      return SQLITE_ERROR;
+    }
+    return getNextString(pParse, &zInput[1], ii-1, ppExpr);
+  }
+
+  if( sqlite3_fts3_enable_parentheses ){
+    if( *zInput=='(' ){
+      int nConsumed = 0;
+      pParse->nNest++;
+      rc = fts3ExprParse(pParse, zInput+1, nInput-1, ppExpr, &nConsumed);
+      if( rc==SQLITE_OK && !*ppExpr ){ rc = SQLITE_DONE; }
+      *pnConsumed = (int)(zInput - z) + 1 + nConsumed;
+      return rc;
+    }else if( *zInput==')' ){
+      pParse->nNest--;
+      *pnConsumed = (int)((zInput - z) + 1);
+      *ppExpr = 0;
+      return SQLITE_DONE;
+    }
+  }
+
+  /* If control flows to this point, this must be a regular token, or 
+  ** the end of the input. Read a regular token using the sqlite3_tokenizer
+  ** interface. Before doing so, figure out if there is an explicit
+  ** column specifier for the token. 
+  **
+  ** TODO: Strangely, it is not possible to associate a column specifier
+  ** with a quoted phrase, only with a single token. Not sure if this was
+  ** an implementation artifact or an intentional decision when fts3 was
+  ** first implemented. Whichever it was, this module duplicates the 
+  ** limitation.
+  */
+  iCol = pParse->iDefaultCol;
+  iColLen = 0;
+  for(ii=0; ii<pParse->nCol; ii++){
+    const char *zStr = pParse->azCol[ii];
+    int nStr = (int)strlen(zStr);
+    if( nInput>nStr && zInput[nStr]==':' 
+     && sqlite3_strnicmp(zStr, zInput, nStr)==0 
+    ){
+      iCol = ii;
+      iColLen = (int)((zInput - z) + nStr + 1);
+      break;
+    }
+  }
+  rc = getNextToken(pParse, iCol, &z[iColLen], n-iColLen, ppExpr, pnConsumed);
+  *pnConsumed += iColLen;
+  return rc;
+}
+
+/*
+** The argument is an Fts3Expr structure for a binary operator (any type
+** except an FTSQUERY_PHRASE). Return an integer value representing the
+** precedence of the operator. Lower values have a higher precedence (i.e.
+** group more tightly). For example, in the C language, the == operator
+** groups more tightly than ||, and would therefore have a higher precedence.
+**
+** When using the new fts3 query syntax (when SQLITE_ENABLE_FTS3_PARENTHESIS
+** is defined), the order of the operators in precedence from highest to
+** lowest is:
+**
+**   NEAR
+**   NOT
+**   AND (including implicit ANDs)
+**   OR
+**
+** Note that when using the old query syntax, the OR operator has a higher
+** precedence than the AND operator.
+*/
+static int opPrecedence(Fts3Expr *p){
+  assert( p->eType!=FTSQUERY_PHRASE );
+  if( sqlite3_fts3_enable_parentheses ){
+    return p->eType;
+  }else if( p->eType==FTSQUERY_NEAR ){
+    return 1;
+  }else if( p->eType==FTSQUERY_OR ){
+    return 2;
+  }
+  assert( p->eType==FTSQUERY_AND );
+  return 3;
+}
+
+/*
+** Argument ppHead contains a pointer to the current head of a query 
+** expression tree being parsed. pPrev is the expression node most recently
+** inserted into the tree. This function adds pNew, which is always a binary
+** operator node, into the expression tree based on the relative precedence
+** of pNew and the existing nodes of the tree. This may result in the head
+** of the tree changing, in which case *ppHead is set to the new root node.
+*/
+static void insertBinaryOperator(
+  Fts3Expr **ppHead,       /* Pointer to the root node of a tree */
+  Fts3Expr *pPrev,         /* Node most recently inserted into the tree */
+  Fts3Expr *pNew           /* New binary node to insert into expression tree */
+){
+  Fts3Expr *pSplit = pPrev;
+  while( pSplit->pParent && opPrecedence(pSplit->pParent)<=opPrecedence(pNew) ){
+    pSplit = pSplit->pParent;
+  }
+
+  if( pSplit->pParent ){
+    assert( pSplit->pParent->pRight==pSplit );
+    pSplit->pParent->pRight = pNew;
+    pNew->pParent = pSplit->pParent;
+  }else{
+    *ppHead = pNew;
+  }
+  pNew->pLeft = pSplit;
+  pSplit->pParent = pNew;
+}
+
+/*
+** Parse the fts3 query expression found in buffer z, length n. This function
+** returns either when the end of the buffer is reached or an unmatched 
+** closing bracket - ')' - is encountered.
+**
+** If successful, SQLITE_OK is returned, *ppExpr is set to point to the
+** parsed form of the expression and *pnConsumed is set to the number of
+** bytes read from buffer z. Otherwise, *ppExpr is set to 0 and SQLITE_NOMEM
+** (out of memory error) or SQLITE_ERROR (parse error) is returned.
+*/
+static int fts3ExprParse(
+  ParseContext *pParse,                   /* fts3 query parse context */
+  const char *z, int n,                   /* Text of MATCH query */
+  Fts3Expr **ppExpr,                      /* OUT: Parsed query structure */
+  int *pnConsumed                         /* OUT: Number of bytes consumed */
+){
+  Fts3Expr *pRet = 0;
+  Fts3Expr *pPrev = 0;
+  Fts3Expr *pNotBranch = 0;               /* Only used in legacy parse mode */
+  int nIn = n;
+  const char *zIn = z;
+  int rc = SQLITE_OK;
+  int isRequirePhrase = 1;
+
+  while( rc==SQLITE_OK ){
+    Fts3Expr *p = 0;
+    int nByte = 0;
+
+    rc = getNextNode(pParse, zIn, nIn, &p, &nByte);
+    assert( nByte>0 || (rc!=SQLITE_OK && p==0) );
+    if( rc==SQLITE_OK ){
+      if( p ){
+        int isPhrase;
+
+        if( !sqlite3_fts3_enable_parentheses 
+            && p->eType==FTSQUERY_PHRASE && pParse->isNot 
+        ){
+          /* Create an implicit NOT operator. */
+          Fts3Expr *pNot = fts3MallocZero(sizeof(Fts3Expr));
+          if( !pNot ){
+            sqlite3Fts3ExprFree(p);
+            rc = SQLITE_NOMEM;
+            goto exprparse_out;
+          }
+          pNot->eType = FTSQUERY_NOT;
+          pNot->pRight = p;
+          p->pParent = pNot;
+          if( pNotBranch ){
+            pNot->pLeft = pNotBranch;
+            pNotBranch->pParent = pNot;
+          }
+          pNotBranch = pNot;
+          p = pPrev;
+        }else{
+          int eType = p->eType;
+          isPhrase = (eType==FTSQUERY_PHRASE || p->pLeft);
+
+          /* The isRequirePhrase variable is set to true if a phrase or
+          ** an expression contained in parenthesis is required. If a
+          ** binary operator (AND, OR, NOT or NEAR) is encounted when
+          ** isRequirePhrase is set, this is a syntax error.
+          */
+          if( !isPhrase && isRequirePhrase ){
+            sqlite3Fts3ExprFree(p);
+            rc = SQLITE_ERROR;
+            goto exprparse_out;
+          }
+
+          if( isPhrase && !isRequirePhrase ){
+            /* Insert an implicit AND operator. */
+            Fts3Expr *pAnd;
+            assert( pRet && pPrev );
+            pAnd = fts3MallocZero(sizeof(Fts3Expr));
+            if( !pAnd ){
+              sqlite3Fts3ExprFree(p);
+              rc = SQLITE_NOMEM;
+              goto exprparse_out;
+            }
+            pAnd->eType = FTSQUERY_AND;
+            insertBinaryOperator(&pRet, pPrev, pAnd);
+            pPrev = pAnd;
+          }
+
+          /* This test catches attempts to make either operand of a NEAR
+           ** operator something other than a phrase. For example, either of
+           ** the following:
+           **
+           **    (bracketed expression) NEAR phrase
+           **    phrase NEAR (bracketed expression)
+           **
+           ** Return an error in either case.
+           */
+          if( pPrev && (
+            (eType==FTSQUERY_NEAR && !isPhrase && pPrev->eType!=FTSQUERY_PHRASE)
+         || (eType!=FTSQUERY_PHRASE && isPhrase && pPrev->eType==FTSQUERY_NEAR)
+          )){
+            sqlite3Fts3ExprFree(p);
+            rc = SQLITE_ERROR;
+            goto exprparse_out;
+          }
+
+          if( isPhrase ){
+            if( pRet ){
+              assert( pPrev && pPrev->pLeft && pPrev->pRight==0 );
+              pPrev->pRight = p;
+              p->pParent = pPrev;
+            }else{
+              pRet = p;
+            }
+          }else{
+            insertBinaryOperator(&pRet, pPrev, p);
+          }
+          isRequirePhrase = !isPhrase;
+        }
+        pPrev = p;
+      }
+      assert( nByte>0 );
+    }
+    assert( rc!=SQLITE_OK || (nByte>0 && nByte<=nIn) );
+    nIn -= nByte;
+    zIn += nByte;
+  }
+
+  if( rc==SQLITE_DONE && pRet && isRequirePhrase ){
+    rc = SQLITE_ERROR;
+  }
+
+  if( rc==SQLITE_DONE ){
+    rc = SQLITE_OK;
+    if( !sqlite3_fts3_enable_parentheses && pNotBranch ){
+      if( !pRet ){
+        rc = SQLITE_ERROR;
+      }else{
+        Fts3Expr *pIter = pNotBranch;
+        while( pIter->pLeft ){
+          pIter = pIter->pLeft;
+        }
+        pIter->pLeft = pRet;
+        pRet->pParent = pIter;
+        pRet = pNotBranch;
+      }
+    }
+  }
+  *pnConsumed = n - nIn;
+
+exprparse_out:
+  if( rc!=SQLITE_OK ){
+    sqlite3Fts3ExprFree(pRet);
+    sqlite3Fts3ExprFree(pNotBranch);
+    pRet = 0;
+  }
+  *ppExpr = pRet;
+  return rc;
+}
+
+/*
+** Return SQLITE_ERROR if the maximum depth of the expression tree passed 
+** as the only argument is more than nMaxDepth.
+*/
+static int fts3ExprCheckDepth(Fts3Expr *p, int nMaxDepth){
+  int rc = SQLITE_OK;
+  if( p ){
+    if( nMaxDepth<0 ){ 
+      rc = SQLITE_TOOBIG;
+    }else{
+      rc = fts3ExprCheckDepth(p->pLeft, nMaxDepth-1);
+      if( rc==SQLITE_OK ){
+        rc = fts3ExprCheckDepth(p->pRight, nMaxDepth-1);
+      }
+    }
+  }
+  return rc;
+}
+
+/*
+** This function attempts to transform the expression tree at (*pp) to
+** an equivalent but more balanced form. The tree is modified in place.
+** If successful, SQLITE_OK is returned and (*pp) set to point to the 
+** new root expression node. 
+**
+** nMaxDepth is the maximum allowable depth of the balanced sub-tree.
+**
+** Otherwise, if an error occurs, an SQLite error code is returned and 
+** expression (*pp) freed.
+*/
+static int fts3ExprBalance(Fts3Expr **pp, int nMaxDepth){
+  int rc = SQLITE_OK;             /* Return code */
+  Fts3Expr *pRoot = *pp;          /* Initial root node */
+  Fts3Expr *pFree = 0;            /* List of free nodes. Linked by pParent. */
+  int eType = pRoot->eType;       /* Type of node in this tree */
+
+  if( nMaxDepth==0 ){
+    rc = SQLITE_ERROR;
+  }
+
+  if( rc==SQLITE_OK ){
+    if( (eType==FTSQUERY_AND || eType==FTSQUERY_OR) ){
+      Fts3Expr **apLeaf;
+      apLeaf = (Fts3Expr **)sqlite3_malloc(sizeof(Fts3Expr *) * nMaxDepth);
+      if( 0==apLeaf ){
+        rc = SQLITE_NOMEM;
+      }else{
+        memset(apLeaf, 0, sizeof(Fts3Expr *) * nMaxDepth);
+      }
+
+      if( rc==SQLITE_OK ){
+        int i;
+        Fts3Expr *p;
+
+        /* Set $p to point to the left-most leaf in the tree of eType nodes. */
+        for(p=pRoot; p->eType==eType; p=p->pLeft){
+          assert( p->pParent==0 || p->pParent->pLeft==p );
+          assert( p->pLeft && p->pRight );
+        }
+
+        /* This loop runs once for each leaf in the tree of eType nodes. */
+        while( 1 ){
+          int iLvl;
+          Fts3Expr *pParent = p->pParent;     /* Current parent of p */
+
+          assert( pParent==0 || pParent->pLeft==p );
+          p->pParent = 0;
+          if( pParent ){
+            pParent->pLeft = 0;
+          }else{
+            pRoot = 0;
+          }
+          rc = fts3ExprBalance(&p, nMaxDepth-1);
+          if( rc!=SQLITE_OK ) break;
+
+          for(iLvl=0; p && iLvl<nMaxDepth; iLvl++){
+            if( apLeaf[iLvl]==0 ){
+              apLeaf[iLvl] = p;
+              p = 0;
+            }else{
+              assert( pFree );
+              pFree->pLeft = apLeaf[iLvl];
+              pFree->pRight = p;
+              pFree->pLeft->pParent = pFree;
+              pFree->pRight->pParent = pFree;
+
+              p = pFree;
+              pFree = pFree->pParent;
+              p->pParent = 0;
+              apLeaf[iLvl] = 0;
+            }
+          }
+          if( p ){
+            sqlite3Fts3ExprFree(p);
+            rc = SQLITE_TOOBIG;
+            break;
+          }
+
+          /* If that was the last leaf node, break out of the loop */
+          if( pParent==0 ) break;
+
+          /* Set $p to point to the next leaf in the tree of eType nodes */
+          for(p=pParent->pRight; p->eType==eType; p=p->pLeft);
+
+          /* Remove pParent from the original tree. */
+          assert( pParent->pParent==0 || pParent->pParent->pLeft==pParent );
+          pParent->pRight->pParent = pParent->pParent;
+          if( pParent->pParent ){
+            pParent->pParent->pLeft = pParent->pRight;
+          }else{
+            assert( pParent==pRoot );
+            pRoot = pParent->pRight;
+          }
+
+          /* Link pParent into the free node list. It will be used as an
+          ** internal node of the new tree.  */
+          pParent->pParent = pFree;
+          pFree = pParent;
+        }
+
+        if( rc==SQLITE_OK ){
+          p = 0;
+          for(i=0; i<nMaxDepth; i++){
+            if( apLeaf[i] ){
+              if( p==0 ){
+                p = apLeaf[i];
+                p->pParent = 0;
+              }else{
+                assert( pFree!=0 );
+                pFree->pRight = p;
+                pFree->pLeft = apLeaf[i];
+                pFree->pLeft->pParent = pFree;
+                pFree->pRight->pParent = pFree;
+
+                p = pFree;
+                pFree = pFree->pParent;
+                p->pParent = 0;
+              }
+            }
+          }
+          pRoot = p;
+        }else{
+          /* An error occurred. Delete the contents of the apLeaf[] array 
+          ** and pFree list. Everything else is cleaned up by the call to
+          ** sqlite3Fts3ExprFree(pRoot) below.  */
+          Fts3Expr *pDel;
+          for(i=0; i<nMaxDepth; i++){
+            sqlite3Fts3ExprFree(apLeaf[i]);
+          }
+          while( (pDel=pFree)!=0 ){
+            pFree = pDel->pParent;
+            sqlite3_free(pDel);
+          }
+        }
+
+        assert( pFree==0 );
+        sqlite3_free( apLeaf );
+      }
+    }else if( eType==FTSQUERY_NOT ){
+      Fts3Expr *pLeft = pRoot->pLeft;
+      Fts3Expr *pRight = pRoot->pRight;
+
+      pRoot->pLeft = 0;
+      pRoot->pRight = 0;
+      pLeft->pParent = 0;
+      pRight->pParent = 0;
+
+      rc = fts3ExprBalance(&pLeft, nMaxDepth-1);
+      if( rc==SQLITE_OK ){
+        rc = fts3ExprBalance(&pRight, nMaxDepth-1);
+      }
+
+      if( rc!=SQLITE_OK ){
+        sqlite3Fts3ExprFree(pRight);
+        sqlite3Fts3ExprFree(pLeft);
+      }else{
+        assert( pLeft && pRight );
+        pRoot->pLeft = pLeft;
+        pLeft->pParent = pRoot;
+        pRoot->pRight = pRight;
+        pRight->pParent = pRoot;
+      }
+    }
+  }
+  
+  if( rc!=SQLITE_OK ){
+    sqlite3Fts3ExprFree(pRoot);
+    pRoot = 0;
+  }
+  *pp = pRoot;
+  return rc;
+}
+
+/*
+** This function is similar to sqlite3Fts3ExprParse(), with the following
+** differences:
+**
+**   1. It does not do expression rebalancing.
+**   2. It does not check that the expression does not exceed the 
+**      maximum allowable depth.
+**   3. Even if it fails, *ppExpr may still be set to point to an 
+**      expression tree. It should be deleted using sqlite3Fts3ExprFree()
+**      in this case.
+*/
+static int fts3ExprParseUnbalanced(
+  sqlite3_tokenizer *pTokenizer,      /* Tokenizer module */
+  int iLangid,                        /* Language id for tokenizer */
+  char **azCol,                       /* Array of column names for fts3 table */
+  int bFts4,                          /* True to allow FTS4-only syntax */
+  int nCol,                           /* Number of entries in azCol[] */
+  int iDefaultCol,                    /* Default column to query */
+  const char *z, int n,               /* Text of MATCH query */
+  Fts3Expr **ppExpr                   /* OUT: Parsed query structure */
+){
+  int nParsed;
+  int rc;
+  ParseContext sParse;
+
+  memset(&sParse, 0, sizeof(ParseContext));
+  sParse.pTokenizer = pTokenizer;
+  sParse.iLangid = iLangid;
+  sParse.azCol = (const char **)azCol;
+  sParse.nCol = nCol;
+  sParse.iDefaultCol = iDefaultCol;
+  sParse.bFts4 = bFts4;
+  if( z==0 ){
+    *ppExpr = 0;
+    return SQLITE_OK;
+  }
+  if( n<0 ){
+    n = (int)strlen(z);
+  }
+  rc = fts3ExprParse(&sParse, z, n, ppExpr, &nParsed);
+  assert( rc==SQLITE_OK || *ppExpr==0 );
+
+  /* Check for mismatched parenthesis */
+  if( rc==SQLITE_OK && sParse.nNest ){
+    rc = SQLITE_ERROR;
+  }
+  
+  return rc;
+}
+
+/*
+** Parameters z and n contain a pointer to and length of a buffer containing
+** an fts3 query expression, respectively. This function attempts to parse the
+** query expression and create a tree of Fts3Expr structures representing the
+** parsed expression. If successful, *ppExpr is set to point to the head
+** of the parsed expression tree and SQLITE_OK is returned. If an error
+** occurs, either SQLITE_NOMEM (out-of-memory error) or SQLITE_ERROR (parse
+** error) is returned and *ppExpr is set to 0.
+**
+** If parameter n is a negative number, then z is assumed to point to a
+** nul-terminated string and the length is determined using strlen().
+**
+** The first parameter, pTokenizer, is passed the fts3 tokenizer module to
+** use to normalize query tokens while parsing the expression. The azCol[]
+** array, which is assumed to contain nCol entries, should contain the names
+** of each column in the target fts3 table, in order from left to right. 
+** Column names must be nul-terminated strings.
+**
+** The iDefaultCol parameter should be passed the index of the table column
+** that appears on the left-hand-side of the MATCH operator (the default
+** column to match against for tokens for which a column name is not explicitly
+** specified as part of the query string), or -1 if tokens may by default
+** match any table column.
+*/
+SQLITE_PRIVATE int sqlite3Fts3ExprParse(
+  sqlite3_tokenizer *pTokenizer,      /* Tokenizer module */
+  int iLangid,                        /* Language id for tokenizer */
+  char **azCol,                       /* Array of column names for fts3 table */
+  int bFts4,                          /* True to allow FTS4-only syntax */
+  int nCol,                           /* Number of entries in azCol[] */
+  int iDefaultCol,                    /* Default column to query */
+  const char *z, int n,               /* Text of MATCH query */
+  Fts3Expr **ppExpr,                  /* OUT: Parsed query structure */
+  char **pzErr                        /* OUT: Error message (sqlite3_malloc) */
+){
+  int rc = fts3ExprParseUnbalanced(
+      pTokenizer, iLangid, azCol, bFts4, nCol, iDefaultCol, z, n, ppExpr
+  );
+  
+  /* Rebalance the expression. And check that its depth does not exceed
+  ** SQLITE_FTS3_MAX_EXPR_DEPTH.  */
+  if( rc==SQLITE_OK && *ppExpr ){
+    rc = fts3ExprBalance(ppExpr, SQLITE_FTS3_MAX_EXPR_DEPTH);
+    if( rc==SQLITE_OK ){
+      rc = fts3ExprCheckDepth(*ppExpr, SQLITE_FTS3_MAX_EXPR_DEPTH);
+    }
+  }
+
+  if( rc!=SQLITE_OK ){
+    sqlite3Fts3ExprFree(*ppExpr);
+    *ppExpr = 0;
+    if( rc==SQLITE_TOOBIG ){
+      sqlite3Fts3ErrMsg(pzErr,
+          "FTS expression tree is too large (maximum depth %d)", 
+          SQLITE_FTS3_MAX_EXPR_DEPTH
+      );
+      rc = SQLITE_ERROR;
+    }else if( rc==SQLITE_ERROR ){
+      sqlite3Fts3ErrMsg(pzErr, "malformed MATCH expression: [%s]", z);
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Free a single node of an expression tree.
+*/
+static void fts3FreeExprNode(Fts3Expr *p){
+  assert( p->eType==FTSQUERY_PHRASE || p->pPhrase==0 );
+  sqlite3Fts3EvalPhraseCleanup(p->pPhrase);
+  sqlite3_free(p->aMI);
+  sqlite3_free(p);
+}
+
+/*
+** Free a parsed fts3 query expression allocated by sqlite3Fts3ExprParse().
+**
+** This function would be simpler if it recursively called itself. But
+** that would mean passing a sufficiently large expression to ExprParse()
+** could cause a stack overflow.
+*/
+SQLITE_PRIVATE void sqlite3Fts3ExprFree(Fts3Expr *pDel){
+  Fts3Expr *p;
+  assert( pDel==0 || pDel->pParent==0 );
+  for(p=pDel; p && (p->pLeft||p->pRight); p=(p->pLeft ? p->pLeft : p->pRight)){
+    assert( p->pParent==0 || p==p->pParent->pRight || p==p->pParent->pLeft );
+  }
+  while( p ){
+    Fts3Expr *pParent = p->pParent;
+    fts3FreeExprNode(p);
+    if( pParent && p==pParent->pLeft && pParent->pRight ){
+      p = pParent->pRight;
+      while( p && (p->pLeft || p->pRight) ){
+        assert( p==p->pParent->pRight || p==p->pParent->pLeft );
+        p = (p->pLeft ? p->pLeft : p->pRight);
+      }
+    }else{
+      p = pParent;
+    }
+  }
+}
+
+/****************************************************************************
+*****************************************************************************
+** Everything after this point is just test code.
+*/
+
+#ifdef SQLITE_TEST
+
+/* #include <stdio.h> */
+
+/*
+** Function to query the hash-table of tokenizers (see README.tokenizers).
+*/
+static int queryTestTokenizer(
+  sqlite3 *db, 
+  const char *zName,  
+  const sqlite3_tokenizer_module **pp
+){
+  int rc;
+  sqlite3_stmt *pStmt;
+  const char zSql[] = "SELECT fts3_tokenizer(?)";
+
+  *pp = 0;
+  rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+
+  sqlite3_bind_text(pStmt, 1, zName, -1, SQLITE_STATIC);
+  if( SQLITE_ROW==sqlite3_step(pStmt) ){
+    if( sqlite3_column_type(pStmt, 0)==SQLITE_BLOB ){
+      memcpy((void *)pp, sqlite3_column_blob(pStmt, 0), sizeof(*pp));
+    }
+  }
+
+  return sqlite3_finalize(pStmt);
+}
+
+/*
+** Return a pointer to a buffer containing a text representation of the
+** expression passed as the first argument. The buffer is obtained from
+** sqlite3_malloc(). It is the responsibility of the caller to use 
+** sqlite3_free() to release the memory. If an OOM condition is encountered,
+** NULL is returned.
+**
+** If the second argument is not NULL, then its contents are prepended to 
+** the returned expression text and then freed using sqlite3_free().
+*/
+static char *exprToString(Fts3Expr *pExpr, char *zBuf){
+  if( pExpr==0 ){
+    return sqlite3_mprintf("");
+  }
+  switch( pExpr->eType ){
+    case FTSQUERY_PHRASE: {
+      Fts3Phrase *pPhrase = pExpr->pPhrase;
+      int i;
+      zBuf = sqlite3_mprintf(
+          "%zPHRASE %d 0", zBuf, pPhrase->iColumn);
+      for(i=0; zBuf && i<pPhrase->nToken; i++){
+        zBuf = sqlite3_mprintf("%z %.*s%s", zBuf, 
+            pPhrase->aToken[i].n, pPhrase->aToken[i].z,
+            (pPhrase->aToken[i].isPrefix?"+":"")
+        );
+      }
+      return zBuf;
+    }
+
+    case FTSQUERY_NEAR:
+      zBuf = sqlite3_mprintf("%zNEAR/%d ", zBuf, pExpr->nNear);
+      break;
+    case FTSQUERY_NOT:
+      zBuf = sqlite3_mprintf("%zNOT ", zBuf);
+      break;
+    case FTSQUERY_AND:
+      zBuf = sqlite3_mprintf("%zAND ", zBuf);
+      break;
+    case FTSQUERY_OR:
+      zBuf = sqlite3_mprintf("%zOR ", zBuf);
+      break;
+  }
+
+  if( zBuf ) zBuf = sqlite3_mprintf("%z{", zBuf);
+  if( zBuf ) zBuf = exprToString(pExpr->pLeft, zBuf);
+  if( zBuf ) zBuf = sqlite3_mprintf("%z} {", zBuf);
+
+  if( zBuf ) zBuf = exprToString(pExpr->pRight, zBuf);
+  if( zBuf ) zBuf = sqlite3_mprintf("%z}", zBuf);
+
+  return zBuf;
+}
+
+/*
+** This is the implementation of a scalar SQL function used to test the 
+** expression parser. It should be called as follows:
+**
+**   fts3_exprtest(<tokenizer>, <expr>, <column 1>, ...);
+**
+** The first argument, <tokenizer>, is the name of the fts3 tokenizer used
+** to parse the query expression (see README.tokenizers). The second argument
+** is the query expression to parse. Each subsequent argument is the name
+** of a column of the fts3 table that the query expression may refer to.
+** For example:
+**
+**   SELECT fts3_exprtest('simple', 'Bill col2:Bloggs', 'col1', 'col2');
+*/
+static void fts3ExprTest(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  sqlite3_tokenizer_module const *pModule = 0;
+  sqlite3_tokenizer *pTokenizer = 0;
+  int rc;
+  char **azCol = 0;
+  const char *zExpr;
+  int nExpr;
+  int nCol;
+  int ii;
+  Fts3Expr *pExpr;
+  char *zBuf = 0;
+  sqlite3 *db = sqlite3_context_db_handle(context);
+
+  if( argc<3 ){
+    sqlite3_result_error(context, 
+        "Usage: fts3_exprtest(tokenizer, expr, col1, ...", -1
+    );
+    return;
+  }
+
+  rc = queryTestTokenizer(db,
+                          (const char *)sqlite3_value_text(argv[0]), &pModule);
+  if( rc==SQLITE_NOMEM ){
+    sqlite3_result_error_nomem(context);
+    goto exprtest_out;
+  }else if( !pModule ){
+    sqlite3_result_error(context, "No such tokenizer module", -1);
+    goto exprtest_out;
+  }
+
+  rc = pModule->xCreate(0, 0, &pTokenizer);
+  assert( rc==SQLITE_NOMEM || rc==SQLITE_OK );
+  if( rc==SQLITE_NOMEM ){
+    sqlite3_result_error_nomem(context);
+    goto exprtest_out;
+  }
+  pTokenizer->pModule = pModule;
+
+  zExpr = (const char *)sqlite3_value_text(argv[1]);
+  nExpr = sqlite3_value_bytes(argv[1]);
+  nCol = argc-2;
+  azCol = (char **)sqlite3_malloc(nCol*sizeof(char *));
+  if( !azCol ){
+    sqlite3_result_error_nomem(context);
+    goto exprtest_out;
+  }
+  for(ii=0; ii<nCol; ii++){
+    azCol[ii] = (char *)sqlite3_value_text(argv[ii+2]);
+  }
+
+  if( sqlite3_user_data(context) ){
+    char *zDummy = 0;
+    rc = sqlite3Fts3ExprParse(
+        pTokenizer, 0, azCol, 0, nCol, nCol, zExpr, nExpr, &pExpr, &zDummy
+    );
+    assert( rc==SQLITE_OK || pExpr==0 );
+    sqlite3_free(zDummy);
+  }else{
+    rc = fts3ExprParseUnbalanced(
+        pTokenizer, 0, azCol, 0, nCol, nCol, zExpr, nExpr, &pExpr
+    );
+  }
+
+  if( rc!=SQLITE_OK && rc!=SQLITE_NOMEM ){
+    sqlite3Fts3ExprFree(pExpr);
+    sqlite3_result_error(context, "Error parsing expression", -1);
+  }else if( rc==SQLITE_NOMEM || !(zBuf = exprToString(pExpr, 0)) ){
+    sqlite3_result_error_nomem(context);
+  }else{
+    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
+    sqlite3_free(zBuf);
+  }
+
+  sqlite3Fts3ExprFree(pExpr);
+
+exprtest_out:
+  if( pModule && pTokenizer ){
+    rc = pModule->xDestroy(pTokenizer);
+  }
+  sqlite3_free(azCol);
+}
+
+/*
+** Register the query expression parser test function fts3_exprtest() 
+** with database connection db. 
+*/
+SQLITE_PRIVATE int sqlite3Fts3ExprInitTestInterface(sqlite3* db){
+  int rc = sqlite3_create_function(
+      db, "fts3_exprtest", -1, SQLITE_UTF8, 0, fts3ExprTest, 0, 0
+  );
+  if( rc==SQLITE_OK ){
+    rc = sqlite3_create_function(db, "fts3_exprtest_rebalance", 
+        -1, SQLITE_UTF8, (void *)1, fts3ExprTest, 0, 0
+    );
+  }
+  return rc;
+}
+
+#endif
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */
+
+/************** End of fts3_expr.c *******************************************/
+/************** Begin file fts3_hash.c ***************************************/
+/*
+** 2001 September 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This is the implementation of generic hash-tables used in SQLite.
+** We've modified it slightly to serve as a standalone hash table
+** implementation for the full-text indexing module.
+*/
+
+/*
+** The code in this file is only compiled if:
+**
+**     * The FTS3 module is being built as an extension
+**       (in which case SQLITE_CORE is not defined), or
+**
+**     * The FTS3 module is being built into the core of
+**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
+*/
+/* #include "fts3Int.h" */
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
+
+/* #include <assert.h> */
+/* #include <stdlib.h> */
+/* #include <string.h> */
+
+/* #include "fts3_hash.h" */
+
+/*
+** Malloc and Free functions
+*/
+static void *fts3HashMalloc(int n){
+  void *p = sqlite3_malloc(n);
+  if( p ){
+    memset(p, 0, n);
+  }
+  return p;
+}
+static void fts3HashFree(void *p){
+  sqlite3_free(p);
+}
+
+/* Turn bulk memory into a hash table object by initializing the
+** fields of the Hash structure.
+**
+** "pNew" is a pointer to the hash table that is to be initialized.
+** keyClass is one of the constants 
+** FTS3_HASH_BINARY or FTS3_HASH_STRING.  The value of keyClass 
+** determines what kind of key the hash table will use.  "copyKey" is
+** true if the hash table should make its own private copy of keys and
+** false if it should just use the supplied pointer.
+*/
+SQLITE_PRIVATE void sqlite3Fts3HashInit(Fts3Hash *pNew, char keyClass, char copyKey){
+  assert( pNew!=0 );
+  assert( keyClass>=FTS3_HASH_STRING && keyClass<=FTS3_HASH_BINARY );
+  pNew->keyClass = keyClass;
+  pNew->copyKey = copyKey;
+  pNew->first = 0;
+  pNew->count = 0;
+  pNew->htsize = 0;
+  pNew->ht = 0;
+}
+
+/* Remove all entries from a hash table.  Reclaim all memory.
+** Call this routine to delete a hash table or to reset a hash table
+** to the empty state.
+*/
+SQLITE_PRIVATE void sqlite3Fts3HashClear(Fts3Hash *pH){
+  Fts3HashElem *elem;         /* For looping over all elements of the table */
+
+  assert( pH!=0 );
+  elem = pH->first;
+  pH->first = 0;
+  fts3HashFree(pH->ht);
+  pH->ht = 0;
+  pH->htsize = 0;
+  while( elem ){
+    Fts3HashElem *next_elem = elem->next;
+    if( pH->copyKey && elem->pKey ){
+      fts3HashFree(elem->pKey);
+    }
+    fts3HashFree(elem);
+    elem = next_elem;
+  }
+  pH->count = 0;
+}
+
+/*
+** Hash and comparison functions when the mode is FTS3_HASH_STRING
+*/
+static int fts3StrHash(const void *pKey, int nKey){
+  const char *z = (const char *)pKey;
+  unsigned h = 0;
+  if( nKey<=0 ) nKey = (int) strlen(z);
+  while( nKey > 0  ){
+    h = (h<<3) ^ h ^ *z++;
+    nKey--;
+  }
+  return (int)(h & 0x7fffffff);
+}
+static int fts3StrCompare(const void *pKey1, int n1, const void *pKey2, int n2){
+  if( n1!=n2 ) return 1;
+  return strncmp((const char*)pKey1,(const char*)pKey2,n1);
+}
+
+/*
+** Hash and comparison functions when the mode is FTS3_HASH_BINARY
+*/
+static int fts3BinHash(const void *pKey, int nKey){
+  int h = 0;
+  const char *z = (const char *)pKey;
+  while( nKey-- > 0 ){
+    h = (h<<3) ^ h ^ *(z++);
+  }
+  return h & 0x7fffffff;
+}
+static int fts3BinCompare(const void *pKey1, int n1, const void *pKey2, int n2){
+  if( n1!=n2 ) return 1;
+  return memcmp(pKey1,pKey2,n1);
+}
+
+/*
+** Return a pointer to the appropriate hash function given the key class.
+**
+** The C syntax in this function definition may be unfamilar to some 
+** programmers, so we provide the following additional explanation:
+**
+** The name of the function is "ftsHashFunction".  The function takes a
+** single parameter "keyClass".  The return value of ftsHashFunction()
+** is a pointer to another function.  Specifically, the return value
+** of ftsHashFunction() is a pointer to a function that takes two parameters
+** with types "const void*" and "int" and returns an "int".
+*/
+static int (*ftsHashFunction(int keyClass))(const void*,int){
+  if( keyClass==FTS3_HASH_STRING ){
+    return &fts3StrHash;
+  }else{
+    assert( keyClass==FTS3_HASH_BINARY );
+    return &fts3BinHash;
+  }
+}
+
+/*
+** Return a pointer to the appropriate hash function given the key class.
+**
+** For help in interpreted the obscure C code in the function definition,
+** see the header comment on the previous function.
+*/
+static int (*ftsCompareFunction(int keyClass))(const void*,int,const void*,int){
+  if( keyClass==FTS3_HASH_STRING ){
+    return &fts3StrCompare;
+  }else{
+    assert( keyClass==FTS3_HASH_BINARY );
+    return &fts3BinCompare;
+  }
+}
+
+/* Link an element into the hash table
+*/
+static void fts3HashInsertElement(
+  Fts3Hash *pH,            /* The complete hash table */
+  struct _fts3ht *pEntry,  /* The entry into which pNew is inserted */
+  Fts3HashElem *pNew       /* The element to be inserted */
+){
+  Fts3HashElem *pHead;     /* First element already in pEntry */
+  pHead = pEntry->chain;
+  if( pHead ){
+    pNew->next = pHead;
+    pNew->prev = pHead->prev;
+    if( pHead->prev ){ pHead->prev->next = pNew; }
+    else             { pH->first = pNew; }
+    pHead->prev = pNew;
+  }else{
+    pNew->next = pH->first;
+    if( pH->first ){ pH->first->prev = pNew; }
+    pNew->prev = 0;
+    pH->first = pNew;
+  }
+  pEntry->count++;
+  pEntry->chain = pNew;
+}
+
+
+/* Resize the hash table so that it cantains "new_size" buckets.
+** "new_size" must be a power of 2.  The hash table might fail 
+** to resize if sqliteMalloc() fails.
+**
+** Return non-zero if a memory allocation error occurs.
+*/
+static int fts3Rehash(Fts3Hash *pH, int new_size){
+  struct _fts3ht *new_ht;          /* The new hash table */
+  Fts3HashElem *elem, *next_elem;  /* For looping over existing elements */
+  int (*xHash)(const void*,int);   /* The hash function */
+
+  assert( (new_size & (new_size-1))==0 );
+  new_ht = (struct _fts3ht *)fts3HashMalloc( new_size*sizeof(struct _fts3ht) );
+  if( new_ht==0 ) return 1;
+  fts3HashFree(pH->ht);
+  pH->ht = new_ht;
+  pH->htsize = new_size;
+  xHash = ftsHashFunction(pH->keyClass);
+  for(elem=pH->first, pH->first=0; elem; elem = next_elem){
+    int h = (*xHash)(elem->pKey, elem->nKey) & (new_size-1);
+    next_elem = elem->next;
+    fts3HashInsertElement(pH, &new_ht[h], elem);
+  }
+  return 0;
+}
+
+/* This function (for internal use only) locates an element in an
+** hash table that matches the given key.  The hash for this key has
+** already been computed and is passed as the 4th parameter.
+*/
+static Fts3HashElem *fts3FindElementByHash(
+  const Fts3Hash *pH, /* The pH to be searched */
+  const void *pKey,   /* The key we are searching for */
+  int nKey,
+  int h               /* The hash for this key. */
+){
+  Fts3HashElem *elem;            /* Used to loop thru the element list */
+  int count;                     /* Number of elements left to test */
+  int (*xCompare)(const void*,int,const void*,int);  /* comparison function */
+
+  if( pH->ht ){
+    struct _fts3ht *pEntry = &pH->ht[h];
+    elem = pEntry->chain;
+    count = pEntry->count;
+    xCompare = ftsCompareFunction(pH->keyClass);
+    while( count-- && elem ){
+      if( (*xCompare)(elem->pKey,elem->nKey,pKey,nKey)==0 ){ 
+        return elem;
+      }
+      elem = elem->next;
+    }
+  }
+  return 0;
+}
+
+/* Remove a single entry from the hash table given a pointer to that
+** element and a hash on the element's key.
+*/
+static void fts3RemoveElementByHash(
+  Fts3Hash *pH,         /* The pH containing "elem" */
+  Fts3HashElem* elem,   /* The element to be removed from the pH */
+  int h                 /* Hash value for the element */
+){
+  struct _fts3ht *pEntry;
+  if( elem->prev ){
+    elem->prev->next = elem->next; 
+  }else{
+    pH->first = elem->next;
+  }
+  if( elem->next ){
+    elem->next->prev = elem->prev;
+  }
+  pEntry = &pH->ht[h];
+  if( pEntry->chain==elem ){
+    pEntry->chain = elem->next;
+  }
+  pEntry->count--;
+  if( pEntry->count<=0 ){
+    pEntry->chain = 0;
+  }
+  if( pH->copyKey && elem->pKey ){
+    fts3HashFree(elem->pKey);
+  }
+  fts3HashFree( elem );
+  pH->count--;
+  if( pH->count<=0 ){
+    assert( pH->first==0 );
+    assert( pH->count==0 );
+    fts3HashClear(pH);
+  }
+}
+
+SQLITE_PRIVATE Fts3HashElem *sqlite3Fts3HashFindElem(
+  const Fts3Hash *pH, 
+  const void *pKey, 
+  int nKey
+){
+  int h;                          /* A hash on key */
+  int (*xHash)(const void*,int);  /* The hash function */
+
+  if( pH==0 || pH->ht==0 ) return 0;
+  xHash = ftsHashFunction(pH->keyClass);
+  assert( xHash!=0 );
+  h = (*xHash)(pKey,nKey);
+  assert( (pH->htsize & (pH->htsize-1))==0 );
+  return fts3FindElementByHash(pH,pKey,nKey, h & (pH->htsize-1));
+}
+
+/* 
+** Attempt to locate an element of the hash table pH with a key
+** that matches pKey,nKey.  Return the data for this element if it is
+** found, or NULL if there is no match.
+*/
+SQLITE_PRIVATE void *sqlite3Fts3HashFind(const Fts3Hash *pH, const void *pKey, int nKey){
+  Fts3HashElem *pElem;            /* The element that matches key (if any) */
+
+  pElem = sqlite3Fts3HashFindElem(pH, pKey, nKey);
+  return pElem ? pElem->data : 0;
+}
+
+/* Insert an element into the hash table pH.  The key is pKey,nKey
+** and the data is "data".
+**
+** If no element exists with a matching key, then a new
+** element is created.  A copy of the key is made if the copyKey
+** flag is set.  NULL is returned.
+**
+** If another element already exists with the same key, then the
+** new data replaces the old data and the old data is returned.
+** The key is not copied in this instance.  If a malloc fails, then
+** the new data is returned and the hash table is unchanged.
+**
+** If the "data" parameter to this function is NULL, then the
+** element corresponding to "key" is removed from the hash table.
+*/
+SQLITE_PRIVATE void *sqlite3Fts3HashInsert(
+  Fts3Hash *pH,        /* The hash table to insert into */
+  const void *pKey,    /* The key */
+  int nKey,            /* Number of bytes in the key */
+  void *data           /* The data */
+){
+  int hraw;                 /* Raw hash value of the key */
+  int h;                    /* the hash of the key modulo hash table size */
+  Fts3HashElem *elem;       /* Used to loop thru the element list */
+  Fts3HashElem *new_elem;   /* New element added to the pH */
+  int (*xHash)(const void*,int);  /* The hash function */
+
+  assert( pH!=0 );
+  xHash = ftsHashFunction(pH->keyClass);
+  assert( xHash!=0 );
+  hraw = (*xHash)(pKey, nKey);
+  assert( (pH->htsize & (pH->htsize-1))==0 );
+  h = hraw & (pH->htsize-1);
+  elem = fts3FindElementByHash(pH,pKey,nKey,h);
+  if( elem ){
+    void *old_data = elem->data;
+    if( data==0 ){
+      fts3RemoveElementByHash(pH,elem,h);
+    }else{
+      elem->data = data;
+    }
+    return old_data;
+  }
+  if( data==0 ) return 0;
+  if( (pH->htsize==0 && fts3Rehash(pH,8))
+   || (pH->count>=pH->htsize && fts3Rehash(pH, pH->htsize*2))
+  ){
+    pH->count = 0;
+    return data;
+  }
+  assert( pH->htsize>0 );
+  new_elem = (Fts3HashElem*)fts3HashMalloc( sizeof(Fts3HashElem) );
+  if( new_elem==0 ) return data;
+  if( pH->copyKey && pKey!=0 ){
+    new_elem->pKey = fts3HashMalloc( nKey );
+    if( new_elem->pKey==0 ){
+      fts3HashFree(new_elem);
+      return data;
+    }
+    memcpy((void*)new_elem->pKey, pKey, nKey);
+  }else{
+    new_elem->pKey = (void*)pKey;
+  }
+  new_elem->nKey = nKey;
+  pH->count++;
+  assert( pH->htsize>0 );
+  assert( (pH->htsize & (pH->htsize-1))==0 );
+  h = hraw & (pH->htsize-1);
+  fts3HashInsertElement(pH, &pH->ht[h], new_elem);
+  new_elem->data = data;
+  return 0;
+}
+
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */
+
+/************** End of fts3_hash.c *******************************************/
+/************** Begin file fts3_porter.c *************************************/
+/*
+** 2006 September 30
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** Implementation of the full-text-search tokenizer that implements
+** a Porter stemmer.
+*/
+
+/*
+** The code in this file is only compiled if:
+**
+**     * The FTS3 module is being built as an extension
+**       (in which case SQLITE_CORE is not defined), or
+**
+**     * The FTS3 module is being built into the core of
+**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
+*/
+/* #include "fts3Int.h" */
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
+
+/* #include <assert.h> */
+/* #include <stdlib.h> */
+/* #include <stdio.h> */
+/* #include <string.h> */
+
+/* #include "fts3_tokenizer.h" */
+
+/*
+** Class derived from sqlite3_tokenizer
+*/
+typedef struct porter_tokenizer {
+  sqlite3_tokenizer base;      /* Base class */
+} porter_tokenizer;
+
+/*
+** Class derived from sqlite3_tokenizer_cursor
+*/
+typedef struct porter_tokenizer_cursor {
+  sqlite3_tokenizer_cursor base;
+  const char *zInput;          /* input we are tokenizing */
+  int nInput;                  /* size of the input */
+  int iOffset;                 /* current position in zInput */
+  int iToken;                  /* index of next token to be returned */
+  char *zToken;                /* storage for current token */
+  int nAllocated;              /* space allocated to zToken buffer */
+} porter_tokenizer_cursor;
+
+
+/*
+** Create a new tokenizer instance.
+*/
+static int porterCreate(
+  int argc, const char * const *argv,
+  sqlite3_tokenizer **ppTokenizer
+){
+  porter_tokenizer *t;
+
+  UNUSED_PARAMETER(argc);
+  UNUSED_PARAMETER(argv);
+
+  t = (porter_tokenizer *) sqlite3_malloc(sizeof(*t));
+  if( t==NULL ) return SQLITE_NOMEM;
+  memset(t, 0, sizeof(*t));
+  *ppTokenizer = &t->base;
+  return SQLITE_OK;
+}
+
+/*
+** Destroy a tokenizer
+*/
+static int porterDestroy(sqlite3_tokenizer *pTokenizer){
+  sqlite3_free(pTokenizer);
+  return SQLITE_OK;
+}
+
+/*
+** Prepare to begin tokenizing a particular string.  The input
+** string to be tokenized is zInput[0..nInput-1].  A cursor
+** used to incrementally tokenize this string is returned in 
+** *ppCursor.
+*/
+static int porterOpen(
+  sqlite3_tokenizer *pTokenizer,         /* The tokenizer */
+  const char *zInput, int nInput,        /* String to be tokenized */
+  sqlite3_tokenizer_cursor **ppCursor    /* OUT: Tokenization cursor */
+){
+  porter_tokenizer_cursor *c;
+
+  UNUSED_PARAMETER(pTokenizer);
+
+  c = (porter_tokenizer_cursor *) sqlite3_malloc(sizeof(*c));
+  if( c==NULL ) return SQLITE_NOMEM;
+
+  c->zInput = zInput;
+  if( zInput==0 ){
+    c->nInput = 0;
+  }else if( nInput<0 ){
+    c->nInput = (int)strlen(zInput);
+  }else{
+    c->nInput = nInput;
+  }
+  c->iOffset = 0;                 /* start tokenizing at the beginning */
+  c->iToken = 0;
+  c->zToken = NULL;               /* no space allocated, yet. */
+  c->nAllocated = 0;
+
+  *ppCursor = &c->base;
+  return SQLITE_OK;
+}
+
+/*
+** Close a tokenization cursor previously opened by a call to
+** porterOpen() above.
+*/
+static int porterClose(sqlite3_tokenizer_cursor *pCursor){
+  porter_tokenizer_cursor *c = (porter_tokenizer_cursor *) pCursor;
+  sqlite3_free(c->zToken);
+  sqlite3_free(c);
+  return SQLITE_OK;
+}
+/*
+** Vowel or consonant
+*/
+static const char cType[] = {
+   0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0,
+   1, 1, 1, 2, 1
+};
+
+/*
+** isConsonant() and isVowel() determine if their first character in
+** the string they point to is a consonant or a vowel, according
+** to Porter ruls.  
+**
+** A consonate is any letter other than 'a', 'e', 'i', 'o', or 'u'.
+** 'Y' is a consonant unless it follows another consonant,
+** in which case it is a vowel.
+**
+** In these routine, the letters are in reverse order.  So the 'y' rule
+** is that 'y' is a consonant unless it is followed by another
+** consonent.
+*/
+static int isVowel(const char*);
+static int isConsonant(const char *z){
+  int j;
+  char x = *z;
+  if( x==0 ) return 0;
+  assert( x>='a' && x<='z' );
+  j = cType[x-'a'];
+  if( j<2 ) return j;
+  return z[1]==0 || isVowel(z + 1);
+}
+static int isVowel(const char *z){
+  int j;
+  char x = *z;
+  if( x==0 ) return 0;
+  assert( x>='a' && x<='z' );
+  j = cType[x-'a'];
+  if( j<2 ) return 1-j;
+  return isConsonant(z + 1);
+}
+
+/*
+** Let any sequence of one or more vowels be represented by V and let
+** C be sequence of one or more consonants.  Then every word can be
+** represented as:
+**
+**           [C] (VC){m} [V]
+**
+** In prose:  A word is an optional consonant followed by zero or
+** vowel-consonant pairs followed by an optional vowel.  "m" is the
+** number of vowel consonant pairs.  This routine computes the value
+** of m for the first i bytes of a word.
+**
+** Return true if the m-value for z is 1 or more.  In other words,
+** return true if z contains at least one vowel that is followed
+** by a consonant.
+**
+** In this routine z[] is in reverse order.  So we are really looking
+** for an instance of a consonant followed by a vowel.
+*/
+static int m_gt_0(const char *z){
+  while( isVowel(z) ){ z++; }
+  if( *z==0 ) return 0;
+  while( isConsonant(z) ){ z++; }
+  return *z!=0;
+}
+
+/* Like mgt0 above except we are looking for a value of m which is
+** exactly 1
+*/
+static int m_eq_1(const char *z){
+  while( isVowel(z) ){ z++; }
+  if( *z==0 ) return 0;
+  while( isConsonant(z) ){ z++; }
+  if( *z==0 ) return 0;
+  while( isVowel(z) ){ z++; }
+  if( *z==0 ) return 1;
+  while( isConsonant(z) ){ z++; }
+  return *z==0;
+}
+
+/* Like mgt0 above except we are looking for a value of m>1 instead
+** or m>0
+*/
+static int m_gt_1(const char *z){
+  while( isVowel(z) ){ z++; }
+  if( *z==0 ) return 0;
+  while( isConsonant(z) ){ z++; }
+  if( *z==0 ) return 0;
+  while( isVowel(z) ){ z++; }
+  if( *z==0 ) return 0;
+  while( isConsonant(z) ){ z++; }
+  return *z!=0;
+}
+
+/*
+** Return TRUE if there is a vowel anywhere within z[0..n-1]
+*/
+static int hasVowel(const char *z){
+  while( isConsonant(z) ){ z++; }
+  return *z!=0;
+}
+
+/*
+** Return TRUE if the word ends in a double consonant.
+**
+** The text is reversed here. So we are really looking at
+** the first two characters of z[].
+*/
+static int doubleConsonant(const char *z){
+  return isConsonant(z) && z[0]==z[1];
+}
+
+/*
+** Return TRUE if the word ends with three letters which
+** are consonant-vowel-consonent and where the final consonant
+** is not 'w', 'x', or 'y'.
+**
+** The word is reversed here.  So we are really checking the
+** first three letters and the first one cannot be in [wxy].
+*/
+static int star_oh(const char *z){
+  return
+    isConsonant(z) &&
+    z[0]!='w' && z[0]!='x' && z[0]!='y' &&
+    isVowel(z+1) &&
+    isConsonant(z+2);
+}
+
+/*
+** If the word ends with zFrom and xCond() is true for the stem
+** of the word that preceeds the zFrom ending, then change the 
+** ending to zTo.
+**
+** The input word *pz and zFrom are both in reverse order.  zTo
+** is in normal order. 
+**
+** Return TRUE if zFrom matches.  Return FALSE if zFrom does not
+** match.  Not that TRUE is returned even if xCond() fails and
+** no substitution occurs.
+*/
+static int stem(
+  char **pz,             /* The word being stemmed (Reversed) */
+  const char *zFrom,     /* If the ending matches this... (Reversed) */
+  const char *zTo,       /* ... change the ending to this (not reversed) */
+  int (*xCond)(const char*)   /* Condition that must be true */
+){
+  char *z = *pz;
+  while( *zFrom && *zFrom==*z ){ z++; zFrom++; }
+  if( *zFrom!=0 ) return 0;
+  if( xCond && !xCond(z) ) return 1;
+  while( *zTo ){
+    *(--z) = *(zTo++);
+  }
+  *pz = z;
+  return 1;
+}
+
+/*
+** This is the fallback stemmer used when the porter stemmer is
+** inappropriate.  The input word is copied into the output with
+** US-ASCII case folding.  If the input word is too long (more
+** than 20 bytes if it contains no digits or more than 6 bytes if
+** it contains digits) then word is truncated to 20 or 6 bytes
+** by taking 10 or 3 bytes from the beginning and end.
+*/
+static void copy_stemmer(const char *zIn, int nIn, char *zOut, int *pnOut){
+  int i, mx, j;
+  int hasDigit = 0;
+  for(i=0; i<nIn; i++){
+    char c = zIn[i];
+    if( c>='A' && c<='Z' ){
+      zOut[i] = c - 'A' + 'a';
+    }else{
+      if( c>='0' && c<='9' ) hasDigit = 1;
+      zOut[i] = c;
+    }
+  }
+  mx = hasDigit ? 3 : 10;
+  if( nIn>mx*2 ){
+    for(j=mx, i=nIn-mx; i<nIn; i++, j++){
+      zOut[j] = zOut[i];
+    }
+    i = j;
+  }
+  zOut[i] = 0;
+  *pnOut = i;
+}
+
+
+/*
+** Stem the input word zIn[0..nIn-1].  Store the output in zOut.
+** zOut is at least big enough to hold nIn bytes.  Write the actual
+** size of the output word (exclusive of the '\0' terminator) into *pnOut.
+**
+** Any upper-case characters in the US-ASCII character set ([A-Z])
+** are converted to lower case.  Upper-case UTF characters are
+** unchanged.
+**
+** Words that are longer than about 20 bytes are stemmed by retaining
+** a few bytes from the beginning and the end of the word.  If the
+** word contains digits, 3 bytes are taken from the beginning and
+** 3 bytes from the end.  For long words without digits, 10 bytes
+** are taken from each end.  US-ASCII case folding still applies.
+** 
+** If the input word contains not digits but does characters not 
+** in [a-zA-Z] then no stemming is attempted and this routine just 
+** copies the input into the input into the output with US-ASCII
+** case folding.
+**
+** Stemming never increases the length of the word.  So there is
+** no chance of overflowing the zOut buffer.
+*/
+static void porter_stemmer(const char *zIn, int nIn, char *zOut, int *pnOut){
+  int i, j;
+  char zReverse[28];
+  char *z, *z2;
+  if( nIn<3 || nIn>=(int)sizeof(zReverse)-7 ){
+    /* The word is too big or too small for the porter stemmer.
+    ** Fallback to the copy stemmer */
+    copy_stemmer(zIn, nIn, zOut, pnOut);
+    return;
+  }
+  for(i=0, j=sizeof(zReverse)-6; i<nIn; i++, j--){
+    char c = zIn[i];
+    if( c>='A' && c<='Z' ){
+      zReverse[j] = c + 'a' - 'A';
+    }else if( c>='a' && c<='z' ){
+      zReverse[j] = c;
+    }else{
+      /* The use of a character not in [a-zA-Z] means that we fallback
+      ** to the copy stemmer */
+      copy_stemmer(zIn, nIn, zOut, pnOut);
+      return;
+    }
+  }
+  memset(&zReverse[sizeof(zReverse)-5], 0, 5);
+  z = &zReverse[j+1];
+
+
+  /* Step 1a */
+  if( z[0]=='s' ){
+    if(
+     !stem(&z, "sess", "ss", 0) &&
+     !stem(&z, "sei", "i", 0)  &&
+     !stem(&z, "ss", "ss", 0)
+    ){
+      z++;
+    }
+  }
+
+  /* Step 1b */  
+  z2 = z;
+  if( stem(&z, "dee", "ee", m_gt_0) ){
+    /* Do nothing.  The work was all in the test */
+  }else if( 
+     (stem(&z, "gni", "", hasVowel) || stem(&z, "de", "", hasVowel))
+      && z!=z2
+  ){
+     if( stem(&z, "ta", "ate", 0) ||
+         stem(&z, "lb", "ble", 0) ||
+         stem(&z, "zi", "ize", 0) ){
+       /* Do nothing.  The work was all in the test */
+     }else if( doubleConsonant(z) && (*z!='l' && *z!='s' && *z!='z') ){
+       z++;
+     }else if( m_eq_1(z) && star_oh(z) ){
+       *(--z) = 'e';
+     }
+  }
+
+  /* Step 1c */
+  if( z[0]=='y' && hasVowel(z+1) ){
+    z[0] = 'i';
+  }
+
+  /* Step 2 */
+  switch( z[1] ){
+   case 'a':
+     if( !stem(&z, "lanoita", "ate", m_gt_0) ){
+       stem(&z, "lanoit", "tion", m_gt_0);
+     }
+     break;
+   case 'c':
+     if( !stem(&z, "icne", "ence", m_gt_0) ){
+       stem(&z, "icna", "ance", m_gt_0);
+     }
+     break;
+   case 'e':
+     stem(&z, "rezi", "ize", m_gt_0);
+     break;
+   case 'g':
+     stem(&z, "igol", "log", m_gt_0);
+     break;
+   case 'l':
+     if( !stem(&z, "ilb", "ble", m_gt_0) 
+      && !stem(&z, "illa", "al", m_gt_0)
+      && !stem(&z, "iltne", "ent", m_gt_0)
+      && !stem(&z, "ile", "e", m_gt_0)
+     ){
+       stem(&z, "ilsuo", "ous", m_gt_0);
+     }
+     break;
+   case 'o':
+     if( !stem(&z, "noitazi", "ize", m_gt_0)
+      && !stem(&z, "noita", "ate", m_gt_0)
+     ){
+       stem(&z, "rota", "ate", m_gt_0);
+     }
+     break;
+   case 's':
+     if( !stem(&z, "msila", "al", m_gt_0)
+      && !stem(&z, "ssenevi", "ive", m_gt_0)
+      && !stem(&z, "ssenluf", "ful", m_gt_0)
+     ){
+       stem(&z, "ssensuo", "ous", m_gt_0);
+     }
+     break;
+   case 't':
+     if( !stem(&z, "itila", "al", m_gt_0)
+      && !stem(&z, "itivi", "ive", m_gt_0)
+     ){
+       stem(&z, "itilib", "ble", m_gt_0);
+     }
+     break;
+  }
+
+  /* Step 3 */
+  switch( z[0] ){
+   case 'e':
+     if( !stem(&z, "etaci", "ic", m_gt_0)
+      && !stem(&z, "evita", "", m_gt_0)
+     ){
+       stem(&z, "ezila", "al", m_gt_0);
+     }
+     break;
+   case 'i':
+     stem(&z, "itici", "ic", m_gt_0);
+     break;
+   case 'l':
+     if( !stem(&z, "laci", "ic", m_gt_0) ){
+       stem(&z, "luf", "", m_gt_0);
+     }
+     break;
+   case 's':
+     stem(&z, "ssen", "", m_gt_0);
+     break;
+  }
+
+  /* Step 4 */
+  switch( z[1] ){
+   case 'a':
+     if( z[0]=='l' && m_gt_1(z+2) ){
+       z += 2;
+     }
+     break;
+   case 'c':
+     if( z[0]=='e' && z[2]=='n' && (z[3]=='a' || z[3]=='e')  && m_gt_1(z+4)  ){
+       z += 4;
+     }
+     break;
+   case 'e':
+     if( z[0]=='r' && m_gt_1(z+2) ){
+       z += 2;
+     }
+     break;
+   case 'i':
+     if( z[0]=='c' && m_gt_1(z+2) ){
+       z += 2;
+     }
+     break;
+   case 'l':
+     if( z[0]=='e' && z[2]=='b' && (z[3]=='a' || z[3]=='i') && m_gt_1(z+4) ){
+       z += 4;
+     }
+     break;
+   case 'n':
+     if( z[0]=='t' ){
+       if( z[2]=='a' ){
+         if( m_gt_1(z+3) ){
+           z += 3;
+         }
+       }else if( z[2]=='e' ){
+         if( !stem(&z, "tneme", "", m_gt_1)
+          && !stem(&z, "tnem", "", m_gt_1)
+         ){
+           stem(&z, "tne", "", m_gt_1);
+         }
+       }
+     }
+     break;
+   case 'o':
+     if( z[0]=='u' ){
+       if( m_gt_1(z+2) ){
+         z += 2;
+       }
+     }else if( z[3]=='s' || z[3]=='t' ){
+       stem(&z, "noi", "", m_gt_1);
+     }
+     break;
+   case 's':
+     if( z[0]=='m' && z[2]=='i' && m_gt_1(z+3) ){
+       z += 3;
+     }
+     break;
+   case 't':
+     if( !stem(&z, "eta", "", m_gt_1) ){
+       stem(&z, "iti", "", m_gt_1);
+     }
+     break;
+   case 'u':
+     if( z[0]=='s' && z[2]=='o' && m_gt_1(z+3) ){
+       z += 3;
+     }
+     break;
+   case 'v':
+   case 'z':
+     if( z[0]=='e' && z[2]=='i' && m_gt_1(z+3) ){
+       z += 3;
+     }
+     break;
+  }
+
+  /* Step 5a */
+  if( z[0]=='e' ){
+    if( m_gt_1(z+1) ){
+      z++;
+    }else if( m_eq_1(z+1) && !star_oh(z+1) ){
+      z++;
+    }
+  }
+
+  /* Step 5b */
+  if( m_gt_1(z) && z[0]=='l' && z[1]=='l' ){
+    z++;
+  }
+
+  /* z[] is now the stemmed word in reverse order.  Flip it back
+  ** around into forward order and return.
+  */
+  *pnOut = i = (int)strlen(z);
+  zOut[i] = 0;
+  while( *z ){
+    zOut[--i] = *(z++);
+  }
+}
+
+/*
+** Characters that can be part of a token.  We assume any character
+** whose value is greater than 0x80 (any UTF character) can be
+** part of a token.  In other words, delimiters all must have
+** values of 0x7f or lower.
+*/
+static const char porterIdChar[] = {
+/* x0 x1 x2 x3 x4 x5 x6 x7 x8 x9 xA xB xC xD xE xF */
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0,  /* 3x */
+    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  /* 4x */
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1,  /* 5x */
+    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  /* 6x */
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0,  /* 7x */
+};
+#define isDelim(C) (((ch=C)&0x80)==0 && (ch<0x30 || !porterIdChar[ch-0x30]))
+
+/*
+** Extract the next token from a tokenization cursor.  The cursor must
+** have been opened by a prior call to porterOpen().
+*/
+static int porterNext(
+  sqlite3_tokenizer_cursor *pCursor,  /* Cursor returned by porterOpen */
+  const char **pzToken,               /* OUT: *pzToken is the token text */
+  int *pnBytes,                       /* OUT: Number of bytes in token */
+  int *piStartOffset,                 /* OUT: Starting offset of token */
+  int *piEndOffset,                   /* OUT: Ending offset of token */
+  int *piPosition                     /* OUT: Position integer of token */
+){
+  porter_tokenizer_cursor *c = (porter_tokenizer_cursor *) pCursor;
+  const char *z = c->zInput;
+
+  while( c->iOffset<c->nInput ){
+    int iStartOffset, ch;
+
+    /* Scan past delimiter characters */
+    while( c->iOffset<c->nInput && isDelim(z[c->iOffset]) ){
+      c->iOffset++;
+    }
+
+    /* Count non-delimiter characters. */
+    iStartOffset = c->iOffset;
+    while( c->iOffset<c->nInput && !isDelim(z[c->iOffset]) ){
+      c->iOffset++;
+    }
+
+    if( c->iOffset>iStartOffset ){
+      int n = c->iOffset-iStartOffset;
+      if( n>c->nAllocated ){
+        char *pNew;
+        c->nAllocated = n+20;
+        pNew = sqlite3_realloc(c->zToken, c->nAllocated);
+        if( !pNew ) return SQLITE_NOMEM;
+        c->zToken = pNew;
+      }
+      porter_stemmer(&z[iStartOffset], n, c->zToken, pnBytes);
+      *pzToken = c->zToken;
+      *piStartOffset = iStartOffset;
+      *piEndOffset = c->iOffset;
+      *piPosition = c->iToken++;
+      return SQLITE_OK;
+    }
+  }
+  return SQLITE_DONE;
+}
+
+/*
+** The set of routines that implement the porter-stemmer tokenizer
+*/
+static const sqlite3_tokenizer_module porterTokenizerModule = {
+  0,
+  porterCreate,
+  porterDestroy,
+  porterOpen,
+  porterClose,
+  porterNext,
+  0
+};
+
+/*
+** Allocate a new porter tokenizer.  Return a pointer to the new
+** tokenizer in *ppModule
+*/
+SQLITE_PRIVATE void sqlite3Fts3PorterTokenizerModule(
+  sqlite3_tokenizer_module const**ppModule
+){
+  *ppModule = &porterTokenizerModule;
+}
+
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */
+
+/************** End of fts3_porter.c *****************************************/
+/************** Begin file fts3_tokenizer.c **********************************/
+/*
+** 2007 June 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This is part of an SQLite module implementing full-text search.
+** This particular file implements the generic tokenizer interface.
+*/
+
+/*
+** The code in this file is only compiled if:
+**
+**     * The FTS3 module is being built as an extension
+**       (in which case SQLITE_CORE is not defined), or
+**
+**     * The FTS3 module is being built into the core of
+**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
+*/
+/* #include "fts3Int.h" */
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
+
+/* #include <assert.h> */
+/* #include <string.h> */
+
+/*
+** Return true if the two-argument version of fts3_tokenizer()
+** has been activated via a prior call to sqlite3_db_config(db,
+** SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER, 1, 0);
+*/
+static int fts3TokenizerEnabled(sqlite3_context *context){
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  int isEnabled = 0;
+  sqlite3_db_config(db,SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER,-1,&isEnabled);
+  return isEnabled;
+}
+
+/*
+** Implementation of the SQL scalar function for accessing the underlying 
+** hash table. This function may be called as follows:
+**
+**   SELECT <function-name>(<key-name>);
+**   SELECT <function-name>(<key-name>, <pointer>);
+**
+** where <function-name> is the name passed as the second argument
+** to the sqlite3Fts3InitHashTable() function (e.g. 'fts3_tokenizer').
+**
+** If the <pointer> argument is specified, it must be a blob value
+** containing a pointer to be stored as the hash data corresponding
+** to the string <key-name>. If <pointer> is not specified, then
+** the string <key-name> must already exist in the has table. Otherwise,
+** an error is returned.
+**
+** Whether or not the <pointer> argument is specified, the value returned
+** is a blob containing the pointer stored as the hash data corresponding
+** to string <key-name> (after the hash-table is updated, if applicable).
+*/
+static void fts3TokenizerFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  Fts3Hash *pHash;
+  void *pPtr = 0;
+  const unsigned char *zName;
+  int nName;
+
+  assert( argc==1 || argc==2 );
+
+  pHash = (Fts3Hash *)sqlite3_user_data(context);
+
+  zName = sqlite3_value_text(argv[0]);
+  nName = sqlite3_value_bytes(argv[0])+1;
+
+  if( argc==2 ){
+    if( fts3TokenizerEnabled(context) ){
+      void *pOld;
+      int n = sqlite3_value_bytes(argv[1]);
+      if( zName==0 || n!=sizeof(pPtr) ){
+        sqlite3_result_error(context, "argument type mismatch", -1);
+        return;
+      }
+      pPtr = *(void **)sqlite3_value_blob(argv[1]);
+      pOld = sqlite3Fts3HashInsert(pHash, (void *)zName, nName, pPtr);
+      if( pOld==pPtr ){
+        sqlite3_result_error(context, "out of memory", -1);
+      }
+    }else{
+      sqlite3_result_error(context, "fts3tokenize disabled", -1);
+      return;
+    }
+  }else{
+    if( zName ){
+      pPtr = sqlite3Fts3HashFind(pHash, zName, nName);
+    }
+    if( !pPtr ){
+      char *zErr = sqlite3_mprintf("unknown tokenizer: %s", zName);
+      sqlite3_result_error(context, zErr, -1);
+      sqlite3_free(zErr);
+      return;
+    }
+  }
+  sqlite3_result_blob(context, (void *)&pPtr, sizeof(pPtr), SQLITE_TRANSIENT);
+}
+
+SQLITE_PRIVATE int sqlite3Fts3IsIdChar(char c){
+  static const char isFtsIdChar[] = {
+      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  /* 0x */
+      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  /* 1x */
+      0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  /* 2x */
+      1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0,  /* 3x */
+      0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  /* 4x */
+      1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1,  /* 5x */
+      0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  /* 6x */
+      1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0,  /* 7x */
+  };
+  return (c&0x80 || isFtsIdChar[(int)(c)]);
+}
+
+SQLITE_PRIVATE const char *sqlite3Fts3NextToken(const char *zStr, int *pn){
+  const char *z1;
+  const char *z2 = 0;
+
+  /* Find the start of the next token. */
+  z1 = zStr;
+  while( z2==0 ){
+    char c = *z1;
+    switch( c ){
+      case '\0': return 0;        /* No more tokens here */
+      case '\'':
+      case '"':
+      case '`': {
+        z2 = z1;
+        while( *++z2 && (*z2!=c || *++z2==c) );
+        break;
+      }
+      case '[':
+        z2 = &z1[1];
+        while( *z2 && z2[0]!=']' ) z2++;
+        if( *z2 ) z2++;
+        break;
+
+      default:
+        if( sqlite3Fts3IsIdChar(*z1) ){
+          z2 = &z1[1];
+          while( sqlite3Fts3IsIdChar(*z2) ) z2++;
+        }else{
+          z1++;
+        }
+    }
+  }
+
+  *pn = (int)(z2-z1);
+  return z1;
+}
+
+SQLITE_PRIVATE int sqlite3Fts3InitTokenizer(
+  Fts3Hash *pHash,                /* Tokenizer hash table */
+  const char *zArg,               /* Tokenizer name */
+  sqlite3_tokenizer **ppTok,      /* OUT: Tokenizer (if applicable) */
+  char **pzErr                    /* OUT: Set to malloced error message */
+){
+  int rc;
+  char *z = (char *)zArg;
+  int n = 0;
+  char *zCopy;
+  char *zEnd;                     /* Pointer to nul-term of zCopy */
+  sqlite3_tokenizer_module *m;
+
+  zCopy = sqlite3_mprintf("%s", zArg);
+  if( !zCopy ) return SQLITE_NOMEM;
+  zEnd = &zCopy[strlen(zCopy)];
+
+  z = (char *)sqlite3Fts3NextToken(zCopy, &n);
+  if( z==0 ){
+    assert( n==0 );
+    z = zCopy;
+  }
+  z[n] = '\0';
+  sqlite3Fts3Dequote(z);
+
+  m = (sqlite3_tokenizer_module *)sqlite3Fts3HashFind(pHash,z,(int)strlen(z)+1);
+  if( !m ){
+    sqlite3Fts3ErrMsg(pzErr, "unknown tokenizer: %s", z);
+    rc = SQLITE_ERROR;
+  }else{
+    char const **aArg = 0;
+    int iArg = 0;
+    z = &z[n+1];
+    while( z<zEnd && (NULL!=(z = (char *)sqlite3Fts3NextToken(z, &n))) ){
+      int nNew = sizeof(char *)*(iArg+1);
+      char const **aNew = (const char **)sqlite3_realloc((void *)aArg, nNew);
+      if( !aNew ){
+        sqlite3_free(zCopy);
+        sqlite3_free((void *)aArg);
+        return SQLITE_NOMEM;
+      }
+      aArg = aNew;
+      aArg[iArg++] = z;
+      z[n] = '\0';
+      sqlite3Fts3Dequote(z);
+      z = &z[n+1];
+    }
+    rc = m->xCreate(iArg, aArg, ppTok);
+    assert( rc!=SQLITE_OK || *ppTok );
+    if( rc!=SQLITE_OK ){
+      sqlite3Fts3ErrMsg(pzErr, "unknown tokenizer");
+    }else{
+      (*ppTok)->pModule = m; 
+    }
+    sqlite3_free((void *)aArg);
+  }
+
+  sqlite3_free(zCopy);
+  return rc;
+}
+
+
+#ifdef SQLITE_TEST
+
+#if defined(INCLUDE_SQLITE_TCL_H)
+#  include "sqlite_tcl.h"
+#else
+#  include "tcl.h"
+#endif
+/* #include <string.h> */
+
+/*
+** Implementation of a special SQL scalar function for testing tokenizers 
+** designed to be used in concert with the Tcl testing framework. This
+** function must be called with two or more arguments:
+**
+**   SELECT <function-name>(<key-name>, ..., <input-string>);
+**
+** where <function-name> is the name passed as the second argument
+** to the sqlite3Fts3InitHashTable() function (e.g. 'fts3_tokenizer')
+** concatenated with the string '_test' (e.g. 'fts3_tokenizer_test').
+**
+** The return value is a string that may be interpreted as a Tcl
+** list. For each token in the <input-string>, three elements are
+** added to the returned list. The first is the token position, the 
+** second is the token text (folded, stemmed, etc.) and the third is the
+** substring of <input-string> associated with the token. For example, 
+** using the built-in "simple" tokenizer:
+**
+**   SELECT fts_tokenizer_test('simple', 'I don't see how');
+**
+** will return the string:
+**
+**   "{0 i I 1 dont don't 2 see see 3 how how}"
+**   
+*/
+static void testFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  Fts3Hash *pHash;
+  sqlite3_tokenizer_module *p;
+  sqlite3_tokenizer *pTokenizer = 0;
+  sqlite3_tokenizer_cursor *pCsr = 0;
+
+  const char *zErr = 0;
+
+  const char *zName;
+  int nName;
+  const char *zInput;
+  int nInput;
+
+  const char *azArg[64];
+
+  const char *zToken;
+  int nToken = 0;
+  int iStart = 0;
+  int iEnd = 0;
+  int iPos = 0;
+  int i;
+
+  Tcl_Obj *pRet;
+
+  if( argc<2 ){
+    sqlite3_result_error(context, "insufficient arguments", -1);
+    return;
+  }
+
+  nName = sqlite3_value_bytes(argv[0]);
+  zName = (const char *)sqlite3_value_text(argv[0]);
+  nInput = sqlite3_value_bytes(argv[argc-1]);
+  zInput = (const char *)sqlite3_value_text(argv[argc-1]);
+
+  pHash = (Fts3Hash *)sqlite3_user_data(context);
+  p = (sqlite3_tokenizer_module *)sqlite3Fts3HashFind(pHash, zName, nName+1);
+
+  if( !p ){
+    char *zErr2 = sqlite3_mprintf("unknown tokenizer: %s", zName);
+    sqlite3_result_error(context, zErr2, -1);
+    sqlite3_free(zErr2);
+    return;
+  }
+
+  pRet = Tcl_NewObj();
+  Tcl_IncrRefCount(pRet);
+
+  for(i=1; i<argc-1; i++){
+    azArg[i-1] = (const char *)sqlite3_value_text(argv[i]);
+  }
+
+  if( SQLITE_OK!=p->xCreate(argc-2, azArg, &pTokenizer) ){
+    zErr = "error in xCreate()";
+    goto finish;
+  }
+  pTokenizer->pModule = p;
+  if( sqlite3Fts3OpenTokenizer(pTokenizer, 0, zInput, nInput, &pCsr) ){
+    zErr = "error in xOpen()";
+    goto finish;
+  }
+
+  while( SQLITE_OK==p->xNext(pCsr, &zToken, &nToken, &iStart, &iEnd, &iPos) ){
+    Tcl_ListObjAppendElement(0, pRet, Tcl_NewIntObj(iPos));
+    Tcl_ListObjAppendElement(0, pRet, Tcl_NewStringObj(zToken, nToken));
+    zToken = &zInput[iStart];
+    nToken = iEnd-iStart;
+    Tcl_ListObjAppendElement(0, pRet, Tcl_NewStringObj(zToken, nToken));
+  }
+
+  if( SQLITE_OK!=p->xClose(pCsr) ){
+    zErr = "error in xClose()";
+    goto finish;
+  }
+  if( SQLITE_OK!=p->xDestroy(pTokenizer) ){
+    zErr = "error in xDestroy()";
+    goto finish;
+  }
+
+finish:
+  if( zErr ){
+    sqlite3_result_error(context, zErr, -1);
+  }else{
+    sqlite3_result_text(context, Tcl_GetString(pRet), -1, SQLITE_TRANSIENT);
+  }
+  Tcl_DecrRefCount(pRet);
+}
+
+static
+int registerTokenizer(
+  sqlite3 *db, 
+  char *zName, 
+  const sqlite3_tokenizer_module *p
+){
+  int rc;
+  sqlite3_stmt *pStmt;
+  const char zSql[] = "SELECT fts3_tokenizer(?, ?)";
+
+  rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+
+  sqlite3_bind_text(pStmt, 1, zName, -1, SQLITE_STATIC);
+  sqlite3_bind_blob(pStmt, 2, &p, sizeof(p), SQLITE_STATIC);
+  sqlite3_step(pStmt);
+
+  return sqlite3_finalize(pStmt);
+}
+
+
+static
+int queryTokenizer(
+  sqlite3 *db, 
+  char *zName,  
+  const sqlite3_tokenizer_module **pp
+){
+  int rc;
+  sqlite3_stmt *pStmt;
+  const char zSql[] = "SELECT fts3_tokenizer(?)";
+
+  *pp = 0;
+  rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+
+  sqlite3_bind_text(pStmt, 1, zName, -1, SQLITE_STATIC);
+  if( SQLITE_ROW==sqlite3_step(pStmt) ){
+    if( sqlite3_column_type(pStmt, 0)==SQLITE_BLOB ){
+      memcpy((void *)pp, sqlite3_column_blob(pStmt, 0), sizeof(*pp));
+    }
+  }
+
+  return sqlite3_finalize(pStmt);
+}
+
+SQLITE_PRIVATE void sqlite3Fts3SimpleTokenizerModule(sqlite3_tokenizer_module const**ppModule);
+
+/*
+** Implementation of the scalar function fts3_tokenizer_internal_test().
+** This function is used for testing only, it is not included in the
+** build unless SQLITE_TEST is defined.
+**
+** The purpose of this is to test that the fts3_tokenizer() function
+** can be used as designed by the C-code in the queryTokenizer and
+** registerTokenizer() functions above. These two functions are repeated
+** in the README.tokenizer file as an example, so it is important to
+** test them.
+**
+** To run the tests, evaluate the fts3_tokenizer_internal_test() scalar
+** function with no arguments. An assert() will fail if a problem is
+** detected. i.e.:
+**
+**     SELECT fts3_tokenizer_internal_test();
+**
+*/
+static void intTestFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  int rc;
+  const sqlite3_tokenizer_module *p1;
+  const sqlite3_tokenizer_module *p2;
+  sqlite3 *db = (sqlite3 *)sqlite3_user_data(context);
+
+  UNUSED_PARAMETER(argc);
+  UNUSED_PARAMETER(argv);
+
+  /* Test the query function */
+  sqlite3Fts3SimpleTokenizerModule(&p1);
+  rc = queryTokenizer(db, "simple", &p2);
+  assert( rc==SQLITE_OK );
+  assert( p1==p2 );
+  rc = queryTokenizer(db, "nosuchtokenizer", &p2);
+  assert( rc==SQLITE_ERROR );
+  assert( p2==0 );
+  assert( 0==strcmp(sqlite3_errmsg(db), "unknown tokenizer: nosuchtokenizer") );
+
+  /* Test the storage function */
+  if( fts3TokenizerEnabled(context) ){
+    rc = registerTokenizer(db, "nosuchtokenizer", p1);
+    assert( rc==SQLITE_OK );
+    rc = queryTokenizer(db, "nosuchtokenizer", &p2);
+    assert( rc==SQLITE_OK );
+    assert( p2==p1 );
+  }
+
+  sqlite3_result_text(context, "ok", -1, SQLITE_STATIC);
+}
+
+#endif
+
+/*
+** Set up SQL objects in database db used to access the contents of
+** the hash table pointed to by argument pHash. The hash table must
+** been initialized to use string keys, and to take a private copy 
+** of the key when a value is inserted. i.e. by a call similar to:
+**
+**    sqlite3Fts3HashInit(pHash, FTS3_HASH_STRING, 1);
+**
+** This function adds a scalar function (see header comment above
+** fts3TokenizerFunc() in this file for details) and, if ENABLE_TABLE is
+** defined at compilation time, a temporary virtual table (see header 
+** comment above struct HashTableVtab) to the database schema. Both 
+** provide read/write access to the contents of *pHash.
+**
+** The third argument to this function, zName, is used as the name
+** of both the scalar and, if created, the virtual table.
+*/
+SQLITE_PRIVATE int sqlite3Fts3InitHashTable(
+  sqlite3 *db, 
+  Fts3Hash *pHash, 
+  const char *zName
+){
+  int rc = SQLITE_OK;
+  void *p = (void *)pHash;
+  const int any = SQLITE_ANY;
+
+#ifdef SQLITE_TEST
+  char *zTest = 0;
+  char *zTest2 = 0;
+  void *pdb = (void *)db;
+  zTest = sqlite3_mprintf("%s_test", zName);
+  zTest2 = sqlite3_mprintf("%s_internal_test", zName);
+  if( !zTest || !zTest2 ){
+    rc = SQLITE_NOMEM;
+  }
+#endif
+
+  if( SQLITE_OK==rc ){
+    rc = sqlite3_create_function(db, zName, 1, any, p, fts3TokenizerFunc, 0, 0);
+  }
+  if( SQLITE_OK==rc ){
+    rc = sqlite3_create_function(db, zName, 2, any, p, fts3TokenizerFunc, 0, 0);
+  }
+#ifdef SQLITE_TEST
+  if( SQLITE_OK==rc ){
+    rc = sqlite3_create_function(db, zTest, -1, any, p, testFunc, 0, 0);
+  }
+  if( SQLITE_OK==rc ){
+    rc = sqlite3_create_function(db, zTest2, 0, any, pdb, intTestFunc, 0, 0);
+  }
+#endif
+
+#ifdef SQLITE_TEST
+  sqlite3_free(zTest);
+  sqlite3_free(zTest2);
+#endif
+
+  return rc;
+}
+
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */
+
+/************** End of fts3_tokenizer.c **************************************/
+/************** Begin file fts3_tokenizer1.c *********************************/
+/*
+** 2006 Oct 10
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** Implementation of the "simple" full-text-search tokenizer.
+*/
+
+/*
+** The code in this file is only compiled if:
+**
+**     * The FTS3 module is being built as an extension
+**       (in which case SQLITE_CORE is not defined), or
+**
+**     * The FTS3 module is being built into the core of
+**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
+*/
+/* #include "fts3Int.h" */
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
+
+/* #include <assert.h> */
+/* #include <stdlib.h> */
+/* #include <stdio.h> */
+/* #include <string.h> */
+
+/* #include "fts3_tokenizer.h" */
+
+typedef struct simple_tokenizer {
+  sqlite3_tokenizer base;
+  char delim[128];             /* flag ASCII delimiters */
+} simple_tokenizer;
+
+typedef struct simple_tokenizer_cursor {
+  sqlite3_tokenizer_cursor base;
+  const char *pInput;          /* input we are tokenizing */
+  int nBytes;                  /* size of the input */
+  int iOffset;                 /* current position in pInput */
+  int iToken;                  /* index of next token to be returned */
+  char *pToken;                /* storage for current token */
+  int nTokenAllocated;         /* space allocated to zToken buffer */
+} simple_tokenizer_cursor;
+
+
+static int simpleDelim(simple_tokenizer *t, unsigned char c){
+  return c<0x80 && t->delim[c];
+}
+static int fts3_isalnum(int x){
+  return (x>='0' && x<='9') || (x>='A' && x<='Z') || (x>='a' && x<='z');
+}
+
+/*
+** Create a new tokenizer instance.
+*/
+static int simpleCreate(
+  int argc, const char * const *argv,
+  sqlite3_tokenizer **ppTokenizer
+){
+  simple_tokenizer *t;
+
+  t = (simple_tokenizer *) sqlite3_malloc(sizeof(*t));
+  if( t==NULL ) return SQLITE_NOMEM;
+  memset(t, 0, sizeof(*t));
+
+  /* TODO(shess) Delimiters need to remain the same from run to run,
+  ** else we need to reindex.  One solution would be a meta-table to
+  ** track such information in the database, then we'd only want this
+  ** information on the initial create.
+  */
+  if( argc>1 ){
+    int i, n = (int)strlen(argv[1]);
+    for(i=0; i<n; i++){
+      unsigned char ch = argv[1][i];
+      /* We explicitly don't support UTF-8 delimiters for now. */
+      if( ch>=0x80 ){
+        sqlite3_free(t);
+        return SQLITE_ERROR;
+      }
+      t->delim[ch] = 1;
+    }
+  } else {
+    /* Mark non-alphanumeric ASCII characters as delimiters */
+    int i;
+    for(i=1; i<0x80; i++){
+      t->delim[i] = !fts3_isalnum(i) ? -1 : 0;
+    }
+  }
+
+  *ppTokenizer = &t->base;
+  return SQLITE_OK;
+}
+
+/*
+** Destroy a tokenizer
+*/
+static int simpleDestroy(sqlite3_tokenizer *pTokenizer){
+  sqlite3_free(pTokenizer);
+  return SQLITE_OK;
+}
+
+/*
+** Prepare to begin tokenizing a particular string.  The input
+** string to be tokenized is pInput[0..nBytes-1].  A cursor
+** used to incrementally tokenize this string is returned in 
+** *ppCursor.
+*/
+static int simpleOpen(
+  sqlite3_tokenizer *pTokenizer,         /* The tokenizer */
+  const char *pInput, int nBytes,        /* String to be tokenized */
+  sqlite3_tokenizer_cursor **ppCursor    /* OUT: Tokenization cursor */
+){
+  simple_tokenizer_cursor *c;
+
+  UNUSED_PARAMETER(pTokenizer);
+
+  c = (simple_tokenizer_cursor *) sqlite3_malloc(sizeof(*c));
+  if( c==NULL ) return SQLITE_NOMEM;
+
+  c->pInput = pInput;
+  if( pInput==0 ){
+    c->nBytes = 0;
+  }else if( nBytes<0 ){
+    c->nBytes = (int)strlen(pInput);
+  }else{
+    c->nBytes = nBytes;
+  }
+  c->iOffset = 0;                 /* start tokenizing at the beginning */
+  c->iToken = 0;
+  c->pToken = NULL;               /* no space allocated, yet. */
+  c->nTokenAllocated = 0;
+
+  *ppCursor = &c->base;
+  return SQLITE_OK;
+}
+
+/*
+** Close a tokenization cursor previously opened by a call to
+** simpleOpen() above.
+*/
+static int simpleClose(sqlite3_tokenizer_cursor *pCursor){
+  simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor;
+  sqlite3_free(c->pToken);
+  sqlite3_free(c);
+  return SQLITE_OK;
+}
+
+/*
+** Extract the next token from a tokenization cursor.  The cursor must
+** have been opened by a prior call to simpleOpen().
+*/
+static int simpleNext(
+  sqlite3_tokenizer_cursor *pCursor,  /* Cursor returned by simpleOpen */
+  const char **ppToken,               /* OUT: *ppToken is the token text */
+  int *pnBytes,                       /* OUT: Number of bytes in token */
+  int *piStartOffset,                 /* OUT: Starting offset of token */
+  int *piEndOffset,                   /* OUT: Ending offset of token */
+  int *piPosition                     /* OUT: Position integer of token */
+){
+  simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor;
+  simple_tokenizer *t = (simple_tokenizer *) pCursor->pTokenizer;
+  unsigned char *p = (unsigned char *)c->pInput;
+
+  while( c->iOffset<c->nBytes ){
+    int iStartOffset;
+
+    /* Scan past delimiter characters */
+    while( c->iOffset<c->nBytes && simpleDelim(t, p[c->iOffset]) ){
+      c->iOffset++;
+    }
+
+    /* Count non-delimiter characters. */
+    iStartOffset = c->iOffset;
+    while( c->iOffset<c->nBytes && !simpleDelim(t, p[c->iOffset]) ){
+      c->iOffset++;
+    }
+
+    if( c->iOffset>iStartOffset ){
+      int i, n = c->iOffset-iStartOffset;
+      if( n>c->nTokenAllocated ){
+        char *pNew;
+        c->nTokenAllocated = n+20;
+        pNew = sqlite3_realloc(c->pToken, c->nTokenAllocated);
+        if( !pNew ) return SQLITE_NOMEM;
+        c->pToken = pNew;
+      }
+      for(i=0; i<n; i++){
+        /* TODO(shess) This needs expansion to handle UTF-8
+        ** case-insensitivity.
+        */
+        unsigned char ch = p[iStartOffset+i];
+        c->pToken[i] = (char)((ch>='A' && ch<='Z') ? ch-'A'+'a' : ch);
+      }
+      *ppToken = c->pToken;
+      *pnBytes = n;
+      *piStartOffset = iStartOffset;
+      *piEndOffset = c->iOffset;
+      *piPosition = c->iToken++;
+
+      return SQLITE_OK;
+    }
+  }
+  return SQLITE_DONE;
+}
+
+/*
+** The set of routines that implement the simple tokenizer
+*/
+static const sqlite3_tokenizer_module simpleTokenizerModule = {
+  0,
+  simpleCreate,
+  simpleDestroy,
+  simpleOpen,
+  simpleClose,
+  simpleNext,
+  0,
+};
+
+/*
+** Allocate a new simple tokenizer.  Return a pointer to the new
+** tokenizer in *ppModule
+*/
+SQLITE_PRIVATE void sqlite3Fts3SimpleTokenizerModule(
+  sqlite3_tokenizer_module const**ppModule
+){
+  *ppModule = &simpleTokenizerModule;
+}
+
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */
+
+/************** End of fts3_tokenizer1.c *************************************/
+/************** Begin file fts3_tokenize_vtab.c ******************************/
+/*
+** 2013 Apr 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains code for the "fts3tokenize" virtual table module.
+** An fts3tokenize virtual table is created as follows:
+**
+**   CREATE VIRTUAL TABLE <tbl> USING fts3tokenize(
+**       <tokenizer-name>, <arg-1>, ...
+**   );
+**
+** The table created has the following schema:
+**
+**   CREATE TABLE <tbl>(input, token, start, end, position)
+**
+** When queried, the query must include a WHERE clause of type:
+**
+**   input = <string>
+**
+** The virtual table module tokenizes this <string>, using the FTS3 
+** tokenizer specified by the arguments to the CREATE VIRTUAL TABLE 
+** statement and returns one row for each token in the result. With
+** fields set as follows:
+**
+**   input:   Always set to a copy of <string>
+**   token:   A token from the input.
+**   start:   Byte offset of the token within the input <string>.
+**   end:     Byte offset of the byte immediately following the end of the
+**            token within the input string.
+**   pos:     Token offset of token within input.
+**
+*/
+/* #include "fts3Int.h" */
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
+
+/* #include <string.h> */
+/* #include <assert.h> */
+
+typedef struct Fts3tokTable Fts3tokTable;
+typedef struct Fts3tokCursor Fts3tokCursor;
+
+/*
+** Virtual table structure.
+*/
+struct Fts3tokTable {
+  sqlite3_vtab base;              /* Base class used by SQLite core */
+  const sqlite3_tokenizer_module *pMod;
+  sqlite3_tokenizer *pTok;
+};
+
+/*
+** Virtual table cursor structure.
+*/
+struct Fts3tokCursor {
+  sqlite3_vtab_cursor base;       /* Base class used by SQLite core */
+  char *zInput;                   /* Input string */
+  sqlite3_tokenizer_cursor *pCsr; /* Cursor to iterate through zInput */
+  int iRowid;                     /* Current 'rowid' value */
+  const char *zToken;             /* Current 'token' value */
+  int nToken;                     /* Size of zToken in bytes */
+  int iStart;                     /* Current 'start' value */
+  int iEnd;                       /* Current 'end' value */
+  int iPos;                       /* Current 'pos' value */
+};
+
+/*
+** Query FTS for the tokenizer implementation named zName.
+*/
+static int fts3tokQueryTokenizer(
+  Fts3Hash *pHash,
+  const char *zName,
+  const sqlite3_tokenizer_module **pp,
+  char **pzErr
+){
+  sqlite3_tokenizer_module *p;
+  int nName = (int)strlen(zName);
+
+  p = (sqlite3_tokenizer_module *)sqlite3Fts3HashFind(pHash, zName, nName+1);
+  if( !p ){
+    sqlite3Fts3ErrMsg(pzErr, "unknown tokenizer: %s", zName);
+    return SQLITE_ERROR;
+  }
+
+  *pp = p;
+  return SQLITE_OK;
+}
+
+/*
+** The second argument, argv[], is an array of pointers to nul-terminated
+** strings. This function makes a copy of the array and strings into a 
+** single block of memory. It then dequotes any of the strings that appear
+** to be quoted.
+**
+** If successful, output parameter *pazDequote is set to point at the
+** array of dequoted strings and SQLITE_OK is returned. The caller is
+** responsible for eventually calling sqlite3_free() to free the array
+** in this case. Or, if an error occurs, an SQLite error code is returned.
+** The final value of *pazDequote is undefined in this case.
+*/
+static int fts3tokDequoteArray(
+  int argc,                       /* Number of elements in argv[] */
+  const char * const *argv,       /* Input array */
+  char ***pazDequote              /* Output array */
+){
+  int rc = SQLITE_OK;             /* Return code */
+  if( argc==0 ){
+    *pazDequote = 0;
+  }else{
+    int i;
+    int nByte = 0;
+    char **azDequote;
+
+    for(i=0; i<argc; i++){
+      nByte += (int)(strlen(argv[i]) + 1);
+    }
+
+    *pazDequote = azDequote = sqlite3_malloc(sizeof(char *)*argc + nByte);
+    if( azDequote==0 ){
+      rc = SQLITE_NOMEM;
+    }else{
+      char *pSpace = (char *)&azDequote[argc];
+      for(i=0; i<argc; i++){
+        int n = (int)strlen(argv[i]);
+        azDequote[i] = pSpace;
+        memcpy(pSpace, argv[i], n+1);
+        sqlite3Fts3Dequote(pSpace);
+        pSpace += (n+1);
+      }
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Schema of the tokenizer table.
+*/
+#define FTS3_TOK_SCHEMA "CREATE TABLE x(input, token, start, end, position)"
+
+/*
+** This function does all the work for both the xConnect and xCreate methods.
+** These tables have no persistent representation of their own, so xConnect
+** and xCreate are identical operations.
+**
+**   argv[0]: module name
+**   argv[1]: database name 
+**   argv[2]: table name
+**   argv[3]: first argument (tokenizer name)
+*/
+static int fts3tokConnectMethod(
+  sqlite3 *db,                    /* Database connection */
+  void *pHash,                    /* Hash table of tokenizers */
+  int argc,                       /* Number of elements in argv array */
+  const char * const *argv,       /* xCreate/xConnect argument array */
+  sqlite3_vtab **ppVtab,          /* OUT: New sqlite3_vtab object */
+  char **pzErr                    /* OUT: sqlite3_malloc'd error message */
+){
+  Fts3tokTable *pTab = 0;
+  const sqlite3_tokenizer_module *pMod = 0;
+  sqlite3_tokenizer *pTok = 0;
+  int rc;
+  char **azDequote = 0;
+  int nDequote;
+
+  rc = sqlite3_declare_vtab(db, FTS3_TOK_SCHEMA);
+  if( rc!=SQLITE_OK ) return rc;
+
+  nDequote = argc-3;
+  rc = fts3tokDequoteArray(nDequote, &argv[3], &azDequote);
+
+  if( rc==SQLITE_OK ){
+    const char *zModule;
+    if( nDequote<1 ){
+      zModule = "simple";
+    }else{
+      zModule = azDequote[0];
+    }
+    rc = fts3tokQueryTokenizer((Fts3Hash*)pHash, zModule, &pMod, pzErr);
+  }
+
+  assert( (rc==SQLITE_OK)==(pMod!=0) );
+  if( rc==SQLITE_OK ){
+    const char * const *azArg = (const char * const *)&azDequote[1];
+    rc = pMod->xCreate((nDequote>1 ? nDequote-1 : 0), azArg, &pTok);
+  }
+
+  if( rc==SQLITE_OK ){
+    pTab = (Fts3tokTable *)sqlite3_malloc(sizeof(Fts3tokTable));
+    if( pTab==0 ){
+      rc = SQLITE_NOMEM;
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    memset(pTab, 0, sizeof(Fts3tokTable));
+    pTab->pMod = pMod;
+    pTab->pTok = pTok;
+    *ppVtab = &pTab->base;
+  }else{
+    if( pTok ){
+      pMod->xDestroy(pTok);
+    }
+  }
+
+  sqlite3_free(azDequote);
+  return rc;
+}
+
+/*
+** This function does the work for both the xDisconnect and xDestroy methods.
+** These tables have no persistent representation of their own, so xDisconnect
+** and xDestroy are identical operations.
+*/
+static int fts3tokDisconnectMethod(sqlite3_vtab *pVtab){
+  Fts3tokTable *pTab = (Fts3tokTable *)pVtab;
+
+  pTab->pMod->xDestroy(pTab->pTok);
+  sqlite3_free(pTab);
+  return SQLITE_OK;
+}
+
+/*
+** xBestIndex - Analyze a WHERE and ORDER BY clause.
+*/
+static int fts3tokBestIndexMethod(
+  sqlite3_vtab *pVTab, 
+  sqlite3_index_info *pInfo
+){
+  int i;
+  UNUSED_PARAMETER(pVTab);
+
+  for(i=0; i<pInfo->nConstraint; i++){
+    if( pInfo->aConstraint[i].usable 
+     && pInfo->aConstraint[i].iColumn==0 
+     && pInfo->aConstraint[i].op==SQLITE_INDEX_CONSTRAINT_EQ 
+    ){
+      pInfo->idxNum = 1;
+      pInfo->aConstraintUsage[i].argvIndex = 1;
+      pInfo->aConstraintUsage[i].omit = 1;
+      pInfo->estimatedCost = 1;
+      return SQLITE_OK;
+    }
+  }
+
+  pInfo->idxNum = 0;
+  assert( pInfo->estimatedCost>1000000.0 );
+
+  return SQLITE_OK;
+}
+
+/*
+** xOpen - Open a cursor.
+*/
+static int fts3tokOpenMethod(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCsr){
+  Fts3tokCursor *pCsr;
+  UNUSED_PARAMETER(pVTab);
+
+  pCsr = (Fts3tokCursor *)sqlite3_malloc(sizeof(Fts3tokCursor));
+  if( pCsr==0 ){
+    return SQLITE_NOMEM;
+  }
+  memset(pCsr, 0, sizeof(Fts3tokCursor));
+
+  *ppCsr = (sqlite3_vtab_cursor *)pCsr;
+  return SQLITE_OK;
+}
+
+/*
+** Reset the tokenizer cursor passed as the only argument. As if it had
+** just been returned by fts3tokOpenMethod().
+*/
+static void fts3tokResetCursor(Fts3tokCursor *pCsr){
+  if( pCsr->pCsr ){
+    Fts3tokTable *pTab = (Fts3tokTable *)(pCsr->base.pVtab);
+    pTab->pMod->xClose(pCsr->pCsr);
+    pCsr->pCsr = 0;
+  }
+  sqlite3_free(pCsr->zInput);
+  pCsr->zInput = 0;
+  pCsr->zToken = 0;
+  pCsr->nToken = 0;
+  pCsr->iStart = 0;
+  pCsr->iEnd = 0;
+  pCsr->iPos = 0;
+  pCsr->iRowid = 0;
+}
+
+/*
+** xClose - Close a cursor.
+*/
+static int fts3tokCloseMethod(sqlite3_vtab_cursor *pCursor){
+  Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
+
+  fts3tokResetCursor(pCsr);
+  sqlite3_free(pCsr);
+  return SQLITE_OK;
+}
+
+/*
+** xNext - Advance the cursor to the next row, if any.
+*/
+static int fts3tokNextMethod(sqlite3_vtab_cursor *pCursor){
+  Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
+  Fts3tokTable *pTab = (Fts3tokTable *)(pCursor->pVtab);
+  int rc;                         /* Return code */
+
+  pCsr->iRowid++;
+  rc = pTab->pMod->xNext(pCsr->pCsr,
+      &pCsr->zToken, &pCsr->nToken,
+      &pCsr->iStart, &pCsr->iEnd, &pCsr->iPos
+  );
+
+  if( rc!=SQLITE_OK ){
+    fts3tokResetCursor(pCsr);
+    if( rc==SQLITE_DONE ) rc = SQLITE_OK;
+  }
+
+  return rc;
+}
+
+/*
+** xFilter - Initialize a cursor to point at the start of its data.
+*/
+static int fts3tokFilterMethod(
+  sqlite3_vtab_cursor *pCursor,   /* The cursor used for this query */
+  int idxNum,                     /* Strategy index */
+  const char *idxStr,             /* Unused */
+  int nVal,                       /* Number of elements in apVal */
+  sqlite3_value **apVal           /* Arguments for the indexing scheme */
+){
+  int rc = SQLITE_ERROR;
+  Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
+  Fts3tokTable *pTab = (Fts3tokTable *)(pCursor->pVtab);
+  UNUSED_PARAMETER(idxStr);
+  UNUSED_PARAMETER(nVal);
+
+  fts3tokResetCursor(pCsr);
+  if( idxNum==1 ){
+    const char *zByte = (const char *)sqlite3_value_text(apVal[0]);
+    int nByte = sqlite3_value_bytes(apVal[0]);
+    pCsr->zInput = sqlite3_malloc(nByte+1);
+    if( pCsr->zInput==0 ){
+      rc = SQLITE_NOMEM;
+    }else{
+      memcpy(pCsr->zInput, zByte, nByte);
+      pCsr->zInput[nByte] = 0;
+      rc = pTab->pMod->xOpen(pTab->pTok, pCsr->zInput, nByte, &pCsr->pCsr);
+      if( rc==SQLITE_OK ){
+        pCsr->pCsr->pTokenizer = pTab->pTok;
+      }
+    }
+  }
+
+  if( rc!=SQLITE_OK ) return rc;
+  return fts3tokNextMethod(pCursor);
+}
+
+/*
+** xEof - Return true if the cursor is at EOF, or false otherwise.
+*/
+static int fts3tokEofMethod(sqlite3_vtab_cursor *pCursor){
+  Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
+  return (pCsr->zToken==0);
+}
+
+/*
+** xColumn - Return a column value.
+*/
+static int fts3tokColumnMethod(
+  sqlite3_vtab_cursor *pCursor,   /* Cursor to retrieve value from */
+  sqlite3_context *pCtx,          /* Context for sqlite3_result_xxx() calls */
+  int iCol                        /* Index of column to read value from */
+){
+  Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
+
+  /* CREATE TABLE x(input, token, start, end, position) */
+  switch( iCol ){
+    case 0:
+      sqlite3_result_text(pCtx, pCsr->zInput, -1, SQLITE_TRANSIENT);
+      break;
+    case 1:
+      sqlite3_result_text(pCtx, pCsr->zToken, pCsr->nToken, SQLITE_TRANSIENT);
+      break;
+    case 2:
+      sqlite3_result_int(pCtx, pCsr->iStart);
+      break;
+    case 3:
+      sqlite3_result_int(pCtx, pCsr->iEnd);
+      break;
+    default:
+      assert( iCol==4 );
+      sqlite3_result_int(pCtx, pCsr->iPos);
+      break;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** xRowid - Return the current rowid for the cursor.
+*/
+static int fts3tokRowidMethod(
+  sqlite3_vtab_cursor *pCursor,   /* Cursor to retrieve value from */
+  sqlite_int64 *pRowid            /* OUT: Rowid value */
+){
+  Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
+  *pRowid = (sqlite3_int64)pCsr->iRowid;
+  return SQLITE_OK;
+}
+
+/*
+** Register the fts3tok module with database connection db. Return SQLITE_OK
+** if successful or an error code if sqlite3_create_module() fails.
+*/
+SQLITE_PRIVATE int sqlite3Fts3InitTok(sqlite3 *db, Fts3Hash *pHash){
+  static const sqlite3_module fts3tok_module = {
+     0,                           /* iVersion      */
+     fts3tokConnectMethod,        /* xCreate       */
+     fts3tokConnectMethod,        /* xConnect      */
+     fts3tokBestIndexMethod,      /* xBestIndex    */
+     fts3tokDisconnectMethod,     /* xDisconnect   */
+     fts3tokDisconnectMethod,     /* xDestroy      */
+     fts3tokOpenMethod,           /* xOpen         */
+     fts3tokCloseMethod,          /* xClose        */
+     fts3tokFilterMethod,         /* xFilter       */
+     fts3tokNextMethod,           /* xNext         */
+     fts3tokEofMethod,            /* xEof          */
+     fts3tokColumnMethod,         /* xColumn       */
+     fts3tokRowidMethod,          /* xRowid        */
+     0,                           /* xUpdate       */
+     0,                           /* xBegin        */
+     0,                           /* xSync         */
+     0,                           /* xCommit       */
+     0,                           /* xRollback     */
+     0,                           /* xFindFunction */
+     0,                           /* xRename       */
+     0,                           /* xSavepoint    */
+     0,                           /* xRelease      */
+     0                            /* xRollbackTo   */
+  };
+  int rc;                         /* Return code */
+
+  rc = sqlite3_create_module(db, "fts3tokenize", &fts3tok_module, (void*)pHash);
+  return rc;
+}
+
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */
+
+/************** End of fts3_tokenize_vtab.c **********************************/
+/************** Begin file fts3_write.c **************************************/
+/*
+** 2009 Oct 23
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file is part of the SQLite FTS3 extension module. Specifically,
+** this file contains code to insert, update and delete rows from FTS3
+** tables. It also contains code to merge FTS3 b-tree segments. Some
+** of the sub-routines used to merge segments are also used by the query 
+** code in fts3.c.
+*/
+
+/* #include "fts3Int.h" */
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
+
+/* #include <string.h> */
+/* #include <assert.h> */
+/* #include <stdlib.h> */
+
+
+#define FTS_MAX_APPENDABLE_HEIGHT 16
+
+/*
+** When full-text index nodes are loaded from disk, the buffer that they
+** are loaded into has the following number of bytes of padding at the end 
+** of it. i.e. if a full-text index node is 900 bytes in size, then a buffer
+** of 920 bytes is allocated for it.
+**
+** This means that if we have a pointer into a buffer containing node data,
+** it is always safe to read up to two varints from it without risking an
+** overread, even if the node data is corrupted.
+*/
+#define FTS3_NODE_PADDING (FTS3_VARINT_MAX*2)
+
+/*
+** Under certain circumstances, b-tree nodes (doclists) can be loaded into
+** memory incrementally instead of all at once. This can be a big performance
+** win (reduced IO and CPU) if SQLite stops calling the virtual table xNext()
+** method before retrieving all query results (as may happen, for example,
+** if a query has a LIMIT clause).
+**
+** Incremental loading is used for b-tree nodes FTS3_NODE_CHUNK_THRESHOLD 
+** bytes and larger. Nodes are loaded in chunks of FTS3_NODE_CHUNKSIZE bytes.
+** The code is written so that the hard lower-limit for each of these values 
+** is 1. Clearly such small values would be inefficient, but can be useful 
+** for testing purposes.
+**
+** If this module is built with SQLITE_TEST defined, these constants may
+** be overridden at runtime for testing purposes. File fts3_test.c contains
+** a Tcl interface to read and write the values.
+*/
+#ifdef SQLITE_TEST
+int test_fts3_node_chunksize = (4*1024);
+int test_fts3_node_chunk_threshold = (4*1024)*4;
+# define FTS3_NODE_CHUNKSIZE       test_fts3_node_chunksize
+# define FTS3_NODE_CHUNK_THRESHOLD test_fts3_node_chunk_threshold
+#else
+# define FTS3_NODE_CHUNKSIZE (4*1024) 
+# define FTS3_NODE_CHUNK_THRESHOLD (FTS3_NODE_CHUNKSIZE*4)
+#endif
+
+/*
+** The two values that may be meaningfully bound to the :1 parameter in
+** statements SQL_REPLACE_STAT and SQL_SELECT_STAT.
+*/
+#define FTS_STAT_DOCTOTAL      0
+#define FTS_STAT_INCRMERGEHINT 1
+#define FTS_STAT_AUTOINCRMERGE 2
+
+/*
+** If FTS_LOG_MERGES is defined, call sqlite3_log() to report each automatic
+** and incremental merge operation that takes place. This is used for 
+** debugging FTS only, it should not usually be turned on in production
+** systems.
+*/
+#ifdef FTS3_LOG_MERGES
+static void fts3LogMerge(int nMerge, sqlite3_int64 iAbsLevel){
+  sqlite3_log(SQLITE_OK, "%d-way merge from level %d", nMerge, (int)iAbsLevel);
+}
+#else
+#define fts3LogMerge(x, y)
+#endif
+
+
+typedef struct PendingList PendingList;
+typedef struct SegmentNode SegmentNode;
+typedef struct SegmentWriter SegmentWriter;
+
+/*
+** An instance of the following data structure is used to build doclists
+** incrementally. See function fts3PendingListAppend() for details.
+*/
+struct PendingList {
+  int nData;
+  char *aData;
+  int nSpace;
+  sqlite3_int64 iLastDocid;
+  sqlite3_int64 iLastCol;
+  sqlite3_int64 iLastPos;
+};
+
+
+/*
+** Each cursor has a (possibly empty) linked list of the following objects.
+*/
+struct Fts3DeferredToken {
+  Fts3PhraseToken *pToken;        /* Pointer to corresponding expr token */
+  int iCol;                       /* Column token must occur in */
+  Fts3DeferredToken *pNext;       /* Next in list of deferred tokens */
+  PendingList *pList;             /* Doclist is assembled here */
+};
+
+/*
+** An instance of this structure is used to iterate through the terms on
+** a contiguous set of segment b-tree leaf nodes. Although the details of
+** this structure are only manipulated by code in this file, opaque handles
+** of type Fts3SegReader* are also used by code in fts3.c to iterate through
+** terms when querying the full-text index. See functions:
+**
+**   sqlite3Fts3SegReaderNew()
+**   sqlite3Fts3SegReaderFree()
+**   sqlite3Fts3SegReaderIterate()
+**
+** Methods used to manipulate Fts3SegReader structures:
+**
+**   fts3SegReaderNext()
+**   fts3SegReaderFirstDocid()
+**   fts3SegReaderNextDocid()
+*/
+struct Fts3SegReader {
+  int iIdx;                       /* Index within level, or 0x7FFFFFFF for PT */
+  u8 bLookup;                     /* True for a lookup only */
+  u8 rootOnly;                    /* True for a root-only reader */
+
+  sqlite3_int64 iStartBlock;      /* Rowid of first leaf block to traverse */
+  sqlite3_int64 iLeafEndBlock;    /* Rowid of final leaf block to traverse */
+  sqlite3_int64 iEndBlock;        /* Rowid of final block in segment (or 0) */
+  sqlite3_int64 iCurrentBlock;    /* Current leaf block (or 0) */
+
+  char *aNode;                    /* Pointer to node data (or NULL) */
+  int nNode;                      /* Size of buffer at aNode (or 0) */
+  int nPopulate;                  /* If >0, bytes of buffer aNode[] loaded */
+  sqlite3_blob *pBlob;            /* If not NULL, blob handle to read node */
+
+  Fts3HashElem **ppNextElem;
+
+  /* Variables set by fts3SegReaderNext(). These may be read directly
+  ** by the caller. They are valid from the time SegmentReaderNew() returns
+  ** until SegmentReaderNext() returns something other than SQLITE_OK
+  ** (i.e. SQLITE_DONE).
+  */
+  int nTerm;                      /* Number of bytes in current term */
+  char *zTerm;                    /* Pointer to current term */
+  int nTermAlloc;                 /* Allocated size of zTerm buffer */
+  char *aDoclist;                 /* Pointer to doclist of current entry */
+  int nDoclist;                   /* Size of doclist in current entry */
+
+  /* The following variables are used by fts3SegReaderNextDocid() to iterate 
+  ** through the current doclist (aDoclist/nDoclist).
+  */
+  char *pOffsetList;
+  int nOffsetList;                /* For descending pending seg-readers only */
+  sqlite3_int64 iDocid;
+};
+
+#define fts3SegReaderIsPending(p) ((p)->ppNextElem!=0)
+#define fts3SegReaderIsRootOnly(p) ((p)->rootOnly!=0)
+
+/*
+** An instance of this structure is used to create a segment b-tree in the
+** database. The internal details of this type are only accessed by the
+** following functions:
+**
+**   fts3SegWriterAdd()
+**   fts3SegWriterFlush()
+**   fts3SegWriterFree()
+*/
+struct SegmentWriter {
+  SegmentNode *pTree;             /* Pointer to interior tree structure */
+  sqlite3_int64 iFirst;           /* First slot in %_segments written */
+  sqlite3_int64 iFree;            /* Next free slot in %_segments */
+  char *zTerm;                    /* Pointer to previous term buffer */
+  int nTerm;                      /* Number of bytes in zTerm */
+  int nMalloc;                    /* Size of malloc'd buffer at zMalloc */
+  char *zMalloc;                  /* Malloc'd space (possibly) used for zTerm */
+  int nSize;                      /* Size of allocation at aData */
+  int nData;                      /* Bytes of data in aData */
+  char *aData;                    /* Pointer to block from malloc() */
+  i64 nLeafData;                  /* Number of bytes of leaf data written */
+};
+
+/*
+** Type SegmentNode is used by the following three functions to create
+** the interior part of the segment b+-tree structures (everything except
+** the leaf nodes). These functions and type are only ever used by code
+** within the fts3SegWriterXXX() family of functions described above.
+**
+**   fts3NodeAddTerm()
+**   fts3NodeWrite()
+**   fts3NodeFree()
+**
+** When a b+tree is written to the database (either as a result of a merge
+** or the pending-terms table being flushed), leaves are written into the 
+** database file as soon as they are completely populated. The interior of
+** the tree is assembled in memory and written out only once all leaves have
+** been populated and stored. This is Ok, as the b+-tree fanout is usually
+** very large, meaning that the interior of the tree consumes relatively 
+** little memory.
+*/
+struct SegmentNode {
+  SegmentNode *pParent;           /* Parent node (or NULL for root node) */
+  SegmentNode *pRight;            /* Pointer to right-sibling */
+  SegmentNode *pLeftmost;         /* Pointer to left-most node of this depth */
+  int nEntry;                     /* Number of terms written to node so far */
+  char *zTerm;                    /* Pointer to previous term buffer */
+  int nTerm;                      /* Number of bytes in zTerm */
+  int nMalloc;                    /* Size of malloc'd buffer at zMalloc */
+  char *zMalloc;                  /* Malloc'd space (possibly) used for zTerm */
+  int nData;                      /* Bytes of valid data so far */
+  char *aData;                    /* Node data */
+};
+
+/*
+** Valid values for the second argument to fts3SqlStmt().
+*/
+#define SQL_DELETE_CONTENT             0
+#define SQL_IS_EMPTY                   1
+#define SQL_DELETE_ALL_CONTENT         2 
+#define SQL_DELETE_ALL_SEGMENTS        3
+#define SQL_DELETE_ALL_SEGDIR          4
+#define SQL_DELETE_ALL_DOCSIZE         5
+#define SQL_DELETE_ALL_STAT            6
+#define SQL_SELECT_CONTENT_BY_ROWID    7
+#define SQL_NEXT_SEGMENT_INDEX         8
+#define SQL_INSERT_SEGMENTS            9
+#define SQL_NEXT_SEGMENTS_ID          10
+#define SQL_INSERT_SEGDIR             11
+#define SQL_SELECT_LEVEL              12
+#define SQL_SELECT_LEVEL_RANGE        13
+#define SQL_SELECT_LEVEL_COUNT        14
+#define SQL_SELECT_SEGDIR_MAX_LEVEL   15
+#define SQL_DELETE_SEGDIR_LEVEL       16
+#define SQL_DELETE_SEGMENTS_RANGE     17
+#define SQL_CONTENT_INSERT            18
+#define SQL_DELETE_DOCSIZE            19
+#define SQL_REPLACE_DOCSIZE           20
+#define SQL_SELECT_DOCSIZE            21
+#define SQL_SELECT_STAT               22
+#define SQL_REPLACE_STAT              23
+
+#define SQL_SELECT_ALL_PREFIX_LEVEL   24
+#define SQL_DELETE_ALL_TERMS_SEGDIR   25
+#define SQL_DELETE_SEGDIR_RANGE       26
+#define SQL_SELECT_ALL_LANGID         27
+#define SQL_FIND_MERGE_LEVEL          28
+#define SQL_MAX_LEAF_NODE_ESTIMATE    29
+#define SQL_DELETE_SEGDIR_ENTRY       30
+#define SQL_SHIFT_SEGDIR_ENTRY        31
+#define SQL_SELECT_SEGDIR             32
+#define SQL_CHOMP_SEGDIR              33
+#define SQL_SEGMENT_IS_APPENDABLE     34
+#define SQL_SELECT_INDEXES            35
+#define SQL_SELECT_MXLEVEL            36
+
+#define SQL_SELECT_LEVEL_RANGE2       37
+#define SQL_UPDATE_LEVEL_IDX          38
+#define SQL_UPDATE_LEVEL              39
+
+/*
+** This function is used to obtain an SQLite prepared statement handle
+** for the statement identified by the second argument. If successful,
+** *pp is set to the requested statement handle and SQLITE_OK returned.
+** Otherwise, an SQLite error code is returned and *pp is set to 0.
+**
+** If argument apVal is not NULL, then it must point to an array with
+** at least as many entries as the requested statement has bound 
+** parameters. The values are bound to the statements parameters before
+** returning.
+*/
+static int fts3SqlStmt(
+  Fts3Table *p,                   /* Virtual table handle */
+  int eStmt,                      /* One of the SQL_XXX constants above */
+  sqlite3_stmt **pp,              /* OUT: Statement handle */
+  sqlite3_value **apVal           /* Values to bind to statement */
+){
+  const char *azSql[] = {
+/* 0  */  "DELETE FROM %Q.'%q_content' WHERE rowid = ?",
+/* 1  */  "SELECT NOT EXISTS(SELECT docid FROM %Q.'%q_content' WHERE rowid!=?)",
+/* 2  */  "DELETE FROM %Q.'%q_content'",
+/* 3  */  "DELETE FROM %Q.'%q_segments'",
+/* 4  */  "DELETE FROM %Q.'%q_segdir'",
+/* 5  */  "DELETE FROM %Q.'%q_docsize'",
+/* 6  */  "DELETE FROM %Q.'%q_stat'",
+/* 7  */  "SELECT %s WHERE rowid=?",
+/* 8  */  "SELECT (SELECT max(idx) FROM %Q.'%q_segdir' WHERE level = ?) + 1",
+/* 9  */  "REPLACE INTO %Q.'%q_segments'(blockid, block) VALUES(?, ?)",
+/* 10 */  "SELECT coalesce((SELECT max(blockid) FROM %Q.'%q_segments') + 1, 1)",
+/* 11 */  "REPLACE INTO %Q.'%q_segdir' VALUES(?,?,?,?,?,?)",
+
+          /* Return segments in order from oldest to newest.*/ 
+/* 12 */  "SELECT idx, start_block, leaves_end_block, end_block, root "
+            "FROM %Q.'%q_segdir' WHERE level = ? ORDER BY idx ASC",
+/* 13 */  "SELECT idx, start_block, leaves_end_block, end_block, root "
+            "FROM %Q.'%q_segdir' WHERE level BETWEEN ? AND ?"
+            "ORDER BY level DESC, idx ASC",
+
+/* 14 */  "SELECT count(*) FROM %Q.'%q_segdir' WHERE level = ?",
+/* 15 */  "SELECT max(level) FROM %Q.'%q_segdir' WHERE level BETWEEN ? AND ?",
+
+/* 16 */  "DELETE FROM %Q.'%q_segdir' WHERE level = ?",
+/* 17 */  "DELETE FROM %Q.'%q_segments' WHERE blockid BETWEEN ? AND ?",
+/* 18 */  "INSERT INTO %Q.'%q_content' VALUES(%s)",
+/* 19 */  "DELETE FROM %Q.'%q_docsize' WHERE docid = ?",
+/* 20 */  "REPLACE INTO %Q.'%q_docsize' VALUES(?,?)",
+/* 21 */  "SELECT size FROM %Q.'%q_docsize' WHERE docid=?",
+/* 22 */  "SELECT value FROM %Q.'%q_stat' WHERE id=?",
+/* 23 */  "REPLACE INTO %Q.'%q_stat' VALUES(?,?)",
+/* 24 */  "",
+/* 25 */  "",
+
+/* 26 */ "DELETE FROM %Q.'%q_segdir' WHERE level BETWEEN ? AND ?",
+/* 27 */ "SELECT ? UNION SELECT level / (1024 * ?) FROM %Q.'%q_segdir'",
+
+/* This statement is used to determine which level to read the input from
+** when performing an incremental merge. It returns the absolute level number
+** of the oldest level in the db that contains at least ? segments. Or,
+** if no level in the FTS index contains more than ? segments, the statement
+** returns zero rows.  */
+/* 28 */ "SELECT level, count(*) AS cnt FROM %Q.'%q_segdir' "
+         "  GROUP BY level HAVING cnt>=?"
+         "  ORDER BY (level %% 1024) ASC LIMIT 1",
+
+/* Estimate the upper limit on the number of leaf nodes in a new segment
+** created by merging the oldest :2 segments from absolute level :1. See 
+** function sqlite3Fts3Incrmerge() for details.  */
+/* 29 */ "SELECT 2 * total(1 + leaves_end_block - start_block) "
+         "  FROM %Q.'%q_segdir' WHERE level = ? AND idx < ?",
+
+/* SQL_DELETE_SEGDIR_ENTRY
+**   Delete the %_segdir entry on absolute level :1 with index :2.  */
+/* 30 */ "DELETE FROM %Q.'%q_segdir' WHERE level = ? AND idx = ?",
+
+/* SQL_SHIFT_SEGDIR_ENTRY
+**   Modify the idx value for the segment with idx=:3 on absolute level :2
+**   to :1.  */
+/* 31 */ "UPDATE %Q.'%q_segdir' SET idx = ? WHERE level=? AND idx=?",
+
+/* SQL_SELECT_SEGDIR
+**   Read a single entry from the %_segdir table. The entry from absolute 
+**   level :1 with index value :2.  */
+/* 32 */  "SELECT idx, start_block, leaves_end_block, end_block, root "
+            "FROM %Q.'%q_segdir' WHERE level = ? AND idx = ?",
+
+/* SQL_CHOMP_SEGDIR
+**   Update the start_block (:1) and root (:2) fields of the %_segdir
+**   entry located on absolute level :3 with index :4.  */
+/* 33 */  "UPDATE %Q.'%q_segdir' SET start_block = ?, root = ?"
+            "WHERE level = ? AND idx = ?",
+
+/* SQL_SEGMENT_IS_APPENDABLE
+**   Return a single row if the segment with end_block=? is appendable. Or
+**   no rows otherwise.  */
+/* 34 */  "SELECT 1 FROM %Q.'%q_segments' WHERE blockid=? AND block IS NULL",
+
+/* SQL_SELECT_INDEXES
+**   Return the list of valid segment indexes for absolute level ?  */
+/* 35 */  "SELECT idx FROM %Q.'%q_segdir' WHERE level=? ORDER BY 1 ASC",
+
+/* SQL_SELECT_MXLEVEL
+**   Return the largest relative level in the FTS index or indexes.  */
+/* 36 */  "SELECT max( level %% 1024 ) FROM %Q.'%q_segdir'",
+
+          /* Return segments in order from oldest to newest.*/ 
+/* 37 */  "SELECT level, idx, end_block "
+            "FROM %Q.'%q_segdir' WHERE level BETWEEN ? AND ? "
+            "ORDER BY level DESC, idx ASC",
+
+          /* Update statements used while promoting segments */
+/* 38 */  "UPDATE OR FAIL %Q.'%q_segdir' SET level=-1,idx=? "
+            "WHERE level=? AND idx=?",
+/* 39 */  "UPDATE OR FAIL %Q.'%q_segdir' SET level=? WHERE level=-1"
+
+  };
+  int rc = SQLITE_OK;
+  sqlite3_stmt *pStmt;
+
+  assert( SizeofArray(azSql)==SizeofArray(p->aStmt) );
+  assert( eStmt<SizeofArray(azSql) && eStmt>=0 );
+  
+  pStmt = p->aStmt[eStmt];
+  if( !pStmt ){
+    char *zSql;
+    if( eStmt==SQL_CONTENT_INSERT ){
+      zSql = sqlite3_mprintf(azSql[eStmt], p->zDb, p->zName, p->zWriteExprlist);
+    }else if( eStmt==SQL_SELECT_CONTENT_BY_ROWID ){
+      zSql = sqlite3_mprintf(azSql[eStmt], p->zReadExprlist);
+    }else{
+      zSql = sqlite3_mprintf(azSql[eStmt], p->zDb, p->zName);
+    }
+    if( !zSql ){
+      rc = SQLITE_NOMEM;
+    }else{
+      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pStmt, NULL);
+      sqlite3_free(zSql);
+      assert( rc==SQLITE_OK || pStmt==0 );
+      p->aStmt[eStmt] = pStmt;
+    }
+  }
+  if( apVal ){
+    int i;
+    int nParam = sqlite3_bind_parameter_count(pStmt);
+    for(i=0; rc==SQLITE_OK && i<nParam; i++){
+      rc = sqlite3_bind_value(pStmt, i+1, apVal[i]);
+    }
+  }
+  *pp = pStmt;
+  return rc;
+}
+
+
+static int fts3SelectDocsize(
+  Fts3Table *pTab,                /* FTS3 table handle */
+  sqlite3_int64 iDocid,           /* Docid to bind for SQL_SELECT_DOCSIZE */
+  sqlite3_stmt **ppStmt           /* OUT: Statement handle */
+){
+  sqlite3_stmt *pStmt = 0;        /* Statement requested from fts3SqlStmt() */
+  int rc;                         /* Return code */
+
+  rc = fts3SqlStmt(pTab, SQL_SELECT_DOCSIZE, &pStmt, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int64(pStmt, 1, iDocid);
+    rc = sqlite3_step(pStmt);
+    if( rc!=SQLITE_ROW || sqlite3_column_type(pStmt, 0)!=SQLITE_BLOB ){
+      rc = sqlite3_reset(pStmt);
+      if( rc==SQLITE_OK ) rc = FTS_CORRUPT_VTAB;
+      pStmt = 0;
+    }else{
+      rc = SQLITE_OK;
+    }
+  }
+
+  *ppStmt = pStmt;
+  return rc;
+}
+
+SQLITE_PRIVATE int sqlite3Fts3SelectDoctotal(
+  Fts3Table *pTab,                /* Fts3 table handle */
+  sqlite3_stmt **ppStmt           /* OUT: Statement handle */
+){
+  sqlite3_stmt *pStmt = 0;
+  int rc;
+  rc = fts3SqlStmt(pTab, SQL_SELECT_STAT, &pStmt, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int(pStmt, 1, FTS_STAT_DOCTOTAL);
+    if( sqlite3_step(pStmt)!=SQLITE_ROW
+     || sqlite3_column_type(pStmt, 0)!=SQLITE_BLOB
+    ){
+      rc = sqlite3_reset(pStmt);
+      if( rc==SQLITE_OK ) rc = FTS_CORRUPT_VTAB;
+      pStmt = 0;
+    }
+  }
+  *ppStmt = pStmt;
+  return rc;
+}
+
+SQLITE_PRIVATE int sqlite3Fts3SelectDocsize(
+  Fts3Table *pTab,                /* Fts3 table handle */
+  sqlite3_int64 iDocid,           /* Docid to read size data for */
+  sqlite3_stmt **ppStmt           /* OUT: Statement handle */
+){
+  return fts3SelectDocsize(pTab, iDocid, ppStmt);
+}
+
+/*
+** Similar to fts3SqlStmt(). Except, after binding the parameters in
+** array apVal[] to the SQL statement identified by eStmt, the statement
+** is executed.
+**
+** Returns SQLITE_OK if the statement is successfully executed, or an
+** SQLite error code otherwise.
+*/
+static void fts3SqlExec(
+  int *pRC,                /* Result code */
+  Fts3Table *p,            /* The FTS3 table */
+  int eStmt,               /* Index of statement to evaluate */
+  sqlite3_value **apVal    /* Parameters to bind */
+){
+  sqlite3_stmt *pStmt;
+  int rc;
+  if( *pRC ) return;
+  rc = fts3SqlStmt(p, eStmt, &pStmt, apVal); 
+  if( rc==SQLITE_OK ){
+    sqlite3_step(pStmt);
+    rc = sqlite3_reset(pStmt);
+  }
+  *pRC = rc;
+}
+
+
+/*
+** This function ensures that the caller has obtained an exclusive 
+** shared-cache table-lock on the %_segdir table. This is required before 
+** writing data to the fts3 table. If this lock is not acquired first, then
+** the caller may end up attempting to take this lock as part of committing
+** a transaction, causing SQLite to return SQLITE_LOCKED or 
+** LOCKED_SHAREDCACHEto a COMMIT command.
+**
+** It is best to avoid this because if FTS3 returns any error when 
+** committing a transaction, the whole transaction will be rolled back. 
+** And this is not what users expect when they get SQLITE_LOCKED_SHAREDCACHE. 
+** It can still happen if the user locks the underlying tables directly 
+** instead of accessing them via FTS.
+*/
+static int fts3Writelock(Fts3Table *p){
+  int rc = SQLITE_OK;
+  
+  if( p->nPendingData==0 ){
+    sqlite3_stmt *pStmt;
+    rc = fts3SqlStmt(p, SQL_DELETE_SEGDIR_LEVEL, &pStmt, 0);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_null(pStmt, 1);
+      sqlite3_step(pStmt);
+      rc = sqlite3_reset(pStmt);
+    }
+  }
+
+  return rc;
+}
+
+/*
+** FTS maintains a separate indexes for each language-id (a 32-bit integer).
+** Within each language id, a separate index is maintained to store the
+** document terms, and each configured prefix size (configured the FTS 
+** "prefix=" option). And each index consists of multiple levels ("relative
+** levels").
+**
+** All three of these values (the language id, the specific index and the
+** level within the index) are encoded in 64-bit integer values stored
+** in the %_segdir table on disk. This function is used to convert three
+** separate component values into the single 64-bit integer value that
+** can be used to query the %_segdir table.
+**
+** Specifically, each language-id/index combination is allocated 1024 
+** 64-bit integer level values ("absolute levels"). The main terms index
+** for language-id 0 is allocate values 0-1023. The first prefix index
+** (if any) for language-id 0 is allocated values 1024-2047. And so on.
+** Language 1 indexes are allocated immediately following language 0.
+**
+** So, for a system with nPrefix prefix indexes configured, the block of
+** absolute levels that corresponds to language-id iLangid and index 
+** iIndex starts at absolute level ((iLangid * (nPrefix+1) + iIndex) * 1024).
+*/
+static sqlite3_int64 getAbsoluteLevel(
+  Fts3Table *p,                   /* FTS3 table handle */
+  int iLangid,                    /* Language id */
+  int iIndex,                     /* Index in p->aIndex[] */
+  int iLevel                      /* Level of segments */
+){
+  sqlite3_int64 iBase;            /* First absolute level for iLangid/iIndex */
+  assert( iLangid>=0 );
+  assert( p->nIndex>0 );
+  assert( iIndex>=0 && iIndex<p->nIndex );
+
+  iBase = ((sqlite3_int64)iLangid * p->nIndex + iIndex) * FTS3_SEGDIR_MAXLEVEL;
+  return iBase + iLevel;
+}
+
+/*
+** Set *ppStmt to a statement handle that may be used to iterate through
+** all rows in the %_segdir table, from oldest to newest. If successful,
+** return SQLITE_OK. If an error occurs while preparing the statement, 
+** return an SQLite error code.
+**
+** There is only ever one instance of this SQL statement compiled for
+** each FTS3 table.
+**
+** The statement returns the following columns from the %_segdir table:
+**
+**   0: idx
+**   1: start_block
+**   2: leaves_end_block
+**   3: end_block
+**   4: root
+*/
+SQLITE_PRIVATE int sqlite3Fts3AllSegdirs(
+  Fts3Table *p,                   /* FTS3 table */
+  int iLangid,                    /* Language being queried */
+  int iIndex,                     /* Index for p->aIndex[] */
+  int iLevel,                     /* Level to select (relative level) */
+  sqlite3_stmt **ppStmt           /* OUT: Compiled statement */
+){
+  int rc;
+  sqlite3_stmt *pStmt = 0;
+
+  assert( iLevel==FTS3_SEGCURSOR_ALL || iLevel>=0 );
+  assert( iLevel<FTS3_SEGDIR_MAXLEVEL );
+  assert( iIndex>=0 && iIndex<p->nIndex );
+
+  if( iLevel<0 ){
+    /* "SELECT * FROM %_segdir WHERE level BETWEEN ? AND ? ORDER BY ..." */
+    rc = fts3SqlStmt(p, SQL_SELECT_LEVEL_RANGE, &pStmt, 0);
+    if( rc==SQLITE_OK ){ 
+      sqlite3_bind_int64(pStmt, 1, getAbsoluteLevel(p, iLangid, iIndex, 0));
+      sqlite3_bind_int64(pStmt, 2, 
+          getAbsoluteLevel(p, iLangid, iIndex, FTS3_SEGDIR_MAXLEVEL-1)
+      );
+    }
+  }else{
+    /* "SELECT * FROM %_segdir WHERE level = ? ORDER BY ..." */
+    rc = fts3SqlStmt(p, SQL_SELECT_LEVEL, &pStmt, 0);
+    if( rc==SQLITE_OK ){ 
+      sqlite3_bind_int64(pStmt, 1, getAbsoluteLevel(p, iLangid, iIndex,iLevel));
+    }
+  }
+  *ppStmt = pStmt;
+  return rc;
+}
+
+
+/*
+** Append a single varint to a PendingList buffer. SQLITE_OK is returned
+** if successful, or an SQLite error code otherwise.
+**
+** This function also serves to allocate the PendingList structure itself.
+** For example, to create a new PendingList structure containing two
+** varints:
+**
+**   PendingList *p = 0;
+**   fts3PendingListAppendVarint(&p, 1);
+**   fts3PendingListAppendVarint(&p, 2);
+*/
+static int fts3PendingListAppendVarint(
+  PendingList **pp,               /* IN/OUT: Pointer to PendingList struct */
+  sqlite3_int64 i                 /* Value to append to data */
+){
+  PendingList *p = *pp;
+
+  /* Allocate or grow the PendingList as required. */
+  if( !p ){
+    p = sqlite3_malloc(sizeof(*p) + 100);
+    if( !p ){
+      return SQLITE_NOMEM;
+    }
+    p->nSpace = 100;
+    p->aData = (char *)&p[1];
+    p->nData = 0;
+  }
+  else if( p->nData+FTS3_VARINT_MAX+1>p->nSpace ){
+    int nNew = p->nSpace * 2;
+    p = sqlite3_realloc(p, sizeof(*p) + nNew);
+    if( !p ){
+      sqlite3_free(*pp);
+      *pp = 0;
+      return SQLITE_NOMEM;
+    }
+    p->nSpace = nNew;
+    p->aData = (char *)&p[1];
+  }
+
+  /* Append the new serialized varint to the end of the list. */
+  p->nData += sqlite3Fts3PutVarint(&p->aData[p->nData], i);
+  p->aData[p->nData] = '\0';
+  *pp = p;
+  return SQLITE_OK;
+}
+
+/*
+** Add a docid/column/position entry to a PendingList structure. Non-zero
+** is returned if the structure is sqlite3_realloced as part of adding
+** the entry. Otherwise, zero.
+**
+** If an OOM error occurs, *pRc is set to SQLITE_NOMEM before returning.
+** Zero is always returned in this case. Otherwise, if no OOM error occurs,
+** it is set to SQLITE_OK.
+*/
+static int fts3PendingListAppend(
+  PendingList **pp,               /* IN/OUT: PendingList structure */
+  sqlite3_int64 iDocid,           /* Docid for entry to add */
+  sqlite3_int64 iCol,             /* Column for entry to add */
+  sqlite3_int64 iPos,             /* Position of term for entry to add */
+  int *pRc                        /* OUT: Return code */
+){
+  PendingList *p = *pp;
+  int rc = SQLITE_OK;
+
+  assert( !p || p->iLastDocid<=iDocid );
+
+  if( !p || p->iLastDocid!=iDocid ){
+    sqlite3_int64 iDelta = iDocid - (p ? p->iLastDocid : 0);
+    if( p ){
+      assert( p->nData<p->nSpace );
+      assert( p->aData[p->nData]==0 );
+      p->nData++;
+    }
+    if( SQLITE_OK!=(rc = fts3PendingListAppendVarint(&p, iDelta)) ){
+      goto pendinglistappend_out;
+    }
+    p->iLastCol = -1;
+    p->iLastPos = 0;
+    p->iLastDocid = iDocid;
+  }
+  if( iCol>0 && p->iLastCol!=iCol ){
+    if( SQLITE_OK!=(rc = fts3PendingListAppendVarint(&p, 1))
+     || SQLITE_OK!=(rc = fts3PendingListAppendVarint(&p, iCol))
+    ){
+      goto pendinglistappend_out;
+    }
+    p->iLastCol = iCol;
+    p->iLastPos = 0;
+  }
+  if( iCol>=0 ){
+    assert( iPos>p->iLastPos || (iPos==0 && p->iLastPos==0) );
+    rc = fts3PendingListAppendVarint(&p, 2+iPos-p->iLastPos);
+    if( rc==SQLITE_OK ){
+      p->iLastPos = iPos;
+    }
+  }
+
+ pendinglistappend_out:
+  *pRc = rc;
+  if( p!=*pp ){
+    *pp = p;
+    return 1;
+  }
+  return 0;
+}
+
+/*
+** Free a PendingList object allocated by fts3PendingListAppend().
+*/
+static void fts3PendingListDelete(PendingList *pList){
+  sqlite3_free(pList);
+}
+
+/*
+** Add an entry to one of the pending-terms hash tables.
+*/
+static int fts3PendingTermsAddOne(
+  Fts3Table *p,
+  int iCol,
+  int iPos,
+  Fts3Hash *pHash,                /* Pending terms hash table to add entry to */
+  const char *zToken,
+  int nToken
+){
+  PendingList *pList;
+  int rc = SQLITE_OK;
+
+  pList = (PendingList *)fts3HashFind(pHash, zToken, nToken);
+  if( pList ){
+    p->nPendingData -= (pList->nData + nToken + sizeof(Fts3HashElem));
+  }
+  if( fts3PendingListAppend(&pList, p->iPrevDocid, iCol, iPos, &rc) ){
+    if( pList==fts3HashInsert(pHash, zToken, nToken, pList) ){
+      /* Malloc failed while inserting the new entry. This can only 
+      ** happen if there was no previous entry for this token.
+      */
+      assert( 0==fts3HashFind(pHash, zToken, nToken) );
+      sqlite3_free(pList);
+      rc = SQLITE_NOMEM;
+    }
+  }
+  if( rc==SQLITE_OK ){
+    p->nPendingData += (pList->nData + nToken + sizeof(Fts3HashElem));
+  }
+  return rc;
+}
+
+/*
+** Tokenize the nul-terminated string zText and add all tokens to the
+** pending-terms hash-table. The docid used is that currently stored in
+** p->iPrevDocid, and the column is specified by argument iCol.
+**
+** If successful, SQLITE_OK is returned. Otherwise, an SQLite error code.
+*/
+static int fts3PendingTermsAdd(
+  Fts3Table *p,                   /* Table into which text will be inserted */
+  int iLangid,                    /* Language id to use */
+  const char *zText,              /* Text of document to be inserted */
+  int iCol,                       /* Column into which text is being inserted */
+  u32 *pnWord                     /* IN/OUT: Incr. by number tokens inserted */
+){
+  int rc;
+  int iStart = 0;
+  int iEnd = 0;
+  int iPos = 0;
+  int nWord = 0;
+
+  char const *zToken;
+  int nToken = 0;
+
+  sqlite3_tokenizer *pTokenizer = p->pTokenizer;
+  sqlite3_tokenizer_module const *pModule = pTokenizer->pModule;
+  sqlite3_tokenizer_cursor *pCsr;
+  int (*xNext)(sqlite3_tokenizer_cursor *pCursor,
+      const char**,int*,int*,int*,int*);
+
+  assert( pTokenizer && pModule );
+
+  /* If the user has inserted a NULL value, this function may be called with
+  ** zText==0. In this case, add zero token entries to the hash table and 
+  ** return early. */
+  if( zText==0 ){
+    *pnWord = 0;
+    return SQLITE_OK;
+  }
+
+  rc = sqlite3Fts3OpenTokenizer(pTokenizer, iLangid, zText, -1, &pCsr);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+
+  xNext = pModule->xNext;
+  while( SQLITE_OK==rc
+      && SQLITE_OK==(rc = xNext(pCsr, &zToken, &nToken, &iStart, &iEnd, &iPos))
+  ){
+    int i;
+    if( iPos>=nWord ) nWord = iPos+1;
+
+    /* Positions cannot be negative; we use -1 as a terminator internally.
+    ** Tokens must have a non-zero length.
+    */
+    if( iPos<0 || !zToken || nToken<=0 ){
+      rc = SQLITE_ERROR;
+      break;
+    }
+
+    /* Add the term to the terms index */
+    rc = fts3PendingTermsAddOne(
+        p, iCol, iPos, &p->aIndex[0].hPending, zToken, nToken
+    );
+    
+    /* Add the term to each of the prefix indexes that it is not too 
+    ** short for. */
+    for(i=1; rc==SQLITE_OK && i<p->nIndex; i++){
+      struct Fts3Index *pIndex = &p->aIndex[i];
+      if( nToken<pIndex->nPrefix ) continue;
+      rc = fts3PendingTermsAddOne(
+          p, iCol, iPos, &pIndex->hPending, zToken, pIndex->nPrefix
+      );
+    }
+  }
+
+  pModule->xClose(pCsr);
+  *pnWord += nWord;
+  return (rc==SQLITE_DONE ? SQLITE_OK : rc);
+}
+
+/* 
+** Calling this function indicates that subsequent calls to 
+** fts3PendingTermsAdd() are to add term/position-list pairs for the
+** contents of the document with docid iDocid.
+*/
+static int fts3PendingTermsDocid(
+  Fts3Table *p,                   /* Full-text table handle */
+  int bDelete,                    /* True if this op is a delete */
+  int iLangid,                    /* Language id of row being written */
+  sqlite_int64 iDocid             /* Docid of row being written */
+){
+  assert( iLangid>=0 );
+  assert( bDelete==1 || bDelete==0 );
+
+  /* TODO(shess) Explore whether partially flushing the buffer on
+  ** forced-flush would provide better performance.  I suspect that if
+  ** we ordered the doclists by size and flushed the largest until the
+  ** buffer was half empty, that would let the less frequent terms
+  ** generate longer doclists.
+  */
+  if( iDocid<p->iPrevDocid 
+   || (iDocid==p->iPrevDocid && p->bPrevDelete==0)
+   || p->iPrevLangid!=iLangid
+   || p->nPendingData>p->nMaxPendingData 
+  ){
+    int rc = sqlite3Fts3PendingTermsFlush(p);
+    if( rc!=SQLITE_OK ) return rc;
+  }
+  p->iPrevDocid = iDocid;
+  p->iPrevLangid = iLangid;
+  p->bPrevDelete = bDelete;
+  return SQLITE_OK;
+}
+
+/*
+** Discard the contents of the pending-terms hash tables. 
+*/
+SQLITE_PRIVATE void sqlite3Fts3PendingTermsClear(Fts3Table *p){
+  int i;
+  for(i=0; i<p->nIndex; i++){
+    Fts3HashElem *pElem;
+    Fts3Hash *pHash = &p->aIndex[i].hPending;
+    for(pElem=fts3HashFirst(pHash); pElem; pElem=fts3HashNext(pElem)){
+      PendingList *pList = (PendingList *)fts3HashData(pElem);
+      fts3PendingListDelete(pList);
+    }
+    fts3HashClear(pHash);
+  }
+  p->nPendingData = 0;
+}
+
+/*
+** This function is called by the xUpdate() method as part of an INSERT
+** operation. It adds entries for each term in the new record to the
+** pendingTerms hash table.
+**
+** Argument apVal is the same as the similarly named argument passed to
+** fts3InsertData(). Parameter iDocid is the docid of the new row.
+*/
+static int fts3InsertTerms(
+  Fts3Table *p, 
+  int iLangid, 
+  sqlite3_value **apVal, 
+  u32 *aSz
+){
+  int i;                          /* Iterator variable */
+  for(i=2; i<p->nColumn+2; i++){
+    int iCol = i-2;
+    if( p->abNotindexed[iCol]==0 ){
+      const char *zText = (const char *)sqlite3_value_text(apVal[i]);
+      int rc = fts3PendingTermsAdd(p, iLangid, zText, iCol, &aSz[iCol]);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+      aSz[p->nColumn] += sqlite3_value_bytes(apVal[i]);
+    }
+  }
+  return SQLITE_OK;
+}
+
+/*
+** This function is called by the xUpdate() method for an INSERT operation.
+** The apVal parameter is passed a copy of the apVal argument passed by
+** SQLite to the xUpdate() method. i.e:
+**
+**   apVal[0]                Not used for INSERT.
+**   apVal[1]                rowid
+**   apVal[2]                Left-most user-defined column
+**   ...
+**   apVal[p->nColumn+1]     Right-most user-defined column
+**   apVal[p->nColumn+2]     Hidden column with same name as table
+**   apVal[p->nColumn+3]     Hidden "docid" column (alias for rowid)
+**   apVal[p->nColumn+4]     Hidden languageid column
+*/
+static int fts3InsertData(
+  Fts3Table *p,                   /* Full-text table */
+  sqlite3_value **apVal,          /* Array of values to insert */
+  sqlite3_int64 *piDocid          /* OUT: Docid for row just inserted */
+){
+  int rc;                         /* Return code */
+  sqlite3_stmt *pContentInsert;   /* INSERT INTO %_content VALUES(...) */
+
+  if( p->zContentTbl ){
+    sqlite3_value *pRowid = apVal[p->nColumn+3];
+    if( sqlite3_value_type(pRowid)==SQLITE_NULL ){
+      pRowid = apVal[1];
+    }
+    if( sqlite3_value_type(pRowid)!=SQLITE_INTEGER ){
+      return SQLITE_CONSTRAINT;
+    }
+    *piDocid = sqlite3_value_int64(pRowid);
+    return SQLITE_OK;
+  }
+
+  /* Locate the statement handle used to insert data into the %_content
+  ** table. The SQL for this statement is:
+  **
+  **   INSERT INTO %_content VALUES(?, ?, ?, ...)
+  **
+  ** The statement features N '?' variables, where N is the number of user
+  ** defined columns in the FTS3 table, plus one for the docid field.
+  */
+  rc = fts3SqlStmt(p, SQL_CONTENT_INSERT, &pContentInsert, &apVal[1]);
+  if( rc==SQLITE_OK && p->zLanguageid ){
+    rc = sqlite3_bind_int(
+        pContentInsert, p->nColumn+2, 
+        sqlite3_value_int(apVal[p->nColumn+4])
+    );
+  }
+  if( rc!=SQLITE_OK ) return rc;
+
+  /* There is a quirk here. The users INSERT statement may have specified
+  ** a value for the "rowid" field, for the "docid" field, or for both.
+  ** Which is a problem, since "rowid" and "docid" are aliases for the
+  ** same value. For example:
+  **
+  **   INSERT INTO fts3tbl(rowid, docid) VALUES(1, 2);
+  **
+  ** In FTS3, this is an error. It is an error to specify non-NULL values
+  ** for both docid and some other rowid alias.
+  */
+  if( SQLITE_NULL!=sqlite3_value_type(apVal[3+p->nColumn]) ){
+    if( SQLITE_NULL==sqlite3_value_type(apVal[0])
+     && SQLITE_NULL!=sqlite3_value_type(apVal[1])
+    ){
+      /* A rowid/docid conflict. */
+      return SQLITE_ERROR;
+    }
+    rc = sqlite3_bind_value(pContentInsert, 1, apVal[3+p->nColumn]);
+    if( rc!=SQLITE_OK ) return rc;
+  }
+
+  /* Execute the statement to insert the record. Set *piDocid to the 
+  ** new docid value. 
+  */
+  sqlite3_step(pContentInsert);
+  rc = sqlite3_reset(pContentInsert);
+
+  *piDocid = sqlite3_last_insert_rowid(p->db);
+  return rc;
+}
+
+
+
+/*
+** Remove all data from the FTS3 table. Clear the hash table containing
+** pending terms.
+*/
+static int fts3DeleteAll(Fts3Table *p, int bContent){
+  int rc = SQLITE_OK;             /* Return code */
+
+  /* Discard the contents of the pending-terms hash table. */
+  sqlite3Fts3PendingTermsClear(p);
+
+  /* Delete everything from the shadow tables. Except, leave %_content as
+  ** is if bContent is false.  */
+  assert( p->zContentTbl==0 || bContent==0 );
+  if( bContent ) fts3SqlExec(&rc, p, SQL_DELETE_ALL_CONTENT, 0);
+  fts3SqlExec(&rc, p, SQL_DELETE_ALL_SEGMENTS, 0);
+  fts3SqlExec(&rc, p, SQL_DELETE_ALL_SEGDIR, 0);
+  if( p->bHasDocsize ){
+    fts3SqlExec(&rc, p, SQL_DELETE_ALL_DOCSIZE, 0);
+  }
+  if( p->bHasStat ){
+    fts3SqlExec(&rc, p, SQL_DELETE_ALL_STAT, 0);
+  }
+  return rc;
+}
+
+/*
+**
+*/
+static int langidFromSelect(Fts3Table *p, sqlite3_stmt *pSelect){
+  int iLangid = 0;
+  if( p->zLanguageid ) iLangid = sqlite3_column_int(pSelect, p->nColumn+1);
+  return iLangid;
+}
+
+/*
+** The first element in the apVal[] array is assumed to contain the docid
+** (an integer) of a row about to be deleted. Remove all terms from the
+** full-text index.
+*/
+static void fts3DeleteTerms( 
+  int *pRC,               /* Result code */
+  Fts3Table *p,           /* The FTS table to delete from */
+  sqlite3_value *pRowid,  /* The docid to be deleted */
+  u32 *aSz,               /* Sizes of deleted document written here */
+  int *pbFound            /* OUT: Set to true if row really does exist */
+){
+  int rc;
+  sqlite3_stmt *pSelect;
+
+  assert( *pbFound==0 );
+  if( *pRC ) return;
+  rc = fts3SqlStmt(p, SQL_SELECT_CONTENT_BY_ROWID, &pSelect, &pRowid);
+  if( rc==SQLITE_OK ){
+    if( SQLITE_ROW==sqlite3_step(pSelect) ){
+      int i;
+      int iLangid = langidFromSelect(p, pSelect);
+      i64 iDocid = sqlite3_column_int64(pSelect, 0);
+      rc = fts3PendingTermsDocid(p, 1, iLangid, iDocid);
+      for(i=1; rc==SQLITE_OK && i<=p->nColumn; i++){
+        int iCol = i-1;
+        if( p->abNotindexed[iCol]==0 ){
+          const char *zText = (const char *)sqlite3_column_text(pSelect, i);
+          rc = fts3PendingTermsAdd(p, iLangid, zText, -1, &aSz[iCol]);
+          aSz[p->nColumn] += sqlite3_column_bytes(pSelect, i);
+        }
+      }
+      if( rc!=SQLITE_OK ){
+        sqlite3_reset(pSelect);
+        *pRC = rc;
+        return;
+      }
+      *pbFound = 1;
+    }
+    rc = sqlite3_reset(pSelect);
+  }else{
+    sqlite3_reset(pSelect);
+  }
+  *pRC = rc;
+}
+
+/*
+** Forward declaration to account for the circular dependency between
+** functions fts3SegmentMerge() and fts3AllocateSegdirIdx().
+*/
+static int fts3SegmentMerge(Fts3Table *, int, int, int);
+
+/* 
+** This function allocates a new level iLevel index in the segdir table.
+** Usually, indexes are allocated within a level sequentially starting
+** with 0, so the allocated index is one greater than the value returned
+** by:
+**
+**   SELECT max(idx) FROM %_segdir WHERE level = :iLevel
+**
+** However, if there are already FTS3_MERGE_COUNT indexes at the requested
+** level, they are merged into a single level (iLevel+1) segment and the 
+** allocated index is 0.
+**
+** If successful, *piIdx is set to the allocated index slot and SQLITE_OK
+** returned. Otherwise, an SQLite error code is returned.
+*/
+static int fts3AllocateSegdirIdx(
+  Fts3Table *p, 
+  int iLangid,                    /* Language id */
+  int iIndex,                     /* Index for p->aIndex */
+  int iLevel, 
+  int *piIdx
+){
+  int rc;                         /* Return Code */
+  sqlite3_stmt *pNextIdx;         /* Query for next idx at level iLevel */
+  int iNext = 0;                  /* Result of query pNextIdx */
+
+  assert( iLangid>=0 );
+  assert( p->nIndex>=1 );
+
+  /* Set variable iNext to the next available segdir index at level iLevel. */
+  rc = fts3SqlStmt(p, SQL_NEXT_SEGMENT_INDEX, &pNextIdx, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int64(
+        pNextIdx, 1, getAbsoluteLevel(p, iLangid, iIndex, iLevel)
+    );
+    if( SQLITE_ROW==sqlite3_step(pNextIdx) ){
+      iNext = sqlite3_column_int(pNextIdx, 0);
+    }
+    rc = sqlite3_reset(pNextIdx);
+  }
+
+  if( rc==SQLITE_OK ){
+    /* If iNext is FTS3_MERGE_COUNT, indicating that level iLevel is already
+    ** full, merge all segments in level iLevel into a single iLevel+1
+    ** segment and allocate (newly freed) index 0 at level iLevel. Otherwise,
+    ** if iNext is less than FTS3_MERGE_COUNT, allocate index iNext.
+    */
+    if( iNext>=FTS3_MERGE_COUNT ){
+      fts3LogMerge(16, getAbsoluteLevel(p, iLangid, iIndex, iLevel));
+      rc = fts3SegmentMerge(p, iLangid, iIndex, iLevel);
+      *piIdx = 0;
+    }else{
+      *piIdx = iNext;
+    }
+  }
+
+  return rc;
+}
+
+/*
+** The %_segments table is declared as follows:
+**
+**   CREATE TABLE %_segments(blockid INTEGER PRIMARY KEY, block BLOB)
+**
+** This function reads data from a single row of the %_segments table. The
+** specific row is identified by the iBlockid parameter. If paBlob is not
+** NULL, then a buffer is allocated using sqlite3_malloc() and populated
+** with the contents of the blob stored in the "block" column of the 
+** identified table row is. Whether or not paBlob is NULL, *pnBlob is set
+** to the size of the blob in bytes before returning.
+**
+** If an error occurs, or the table does not contain the specified row,
+** an SQLite error code is returned. Otherwise, SQLITE_OK is returned. If
+** paBlob is non-NULL, then it is the responsibility of the caller to
+** eventually free the returned buffer.
+**
+** This function may leave an open sqlite3_blob* handle in the
+** Fts3Table.pSegments variable. This handle is reused by subsequent calls
+** to this function. The handle may be closed by calling the
+** sqlite3Fts3SegmentsClose() function. Reusing a blob handle is a handy
+** performance improvement, but the blob handle should always be closed
+** before control is returned to the user (to prevent a lock being held
+** on the database file for longer than necessary). Thus, any virtual table
+** method (xFilter etc.) that may directly or indirectly call this function
+** must call sqlite3Fts3SegmentsClose() before returning.
+*/
+SQLITE_PRIVATE int sqlite3Fts3ReadBlock(
+  Fts3Table *p,                   /* FTS3 table handle */
+  sqlite3_int64 iBlockid,         /* Access the row with blockid=$iBlockid */
+  char **paBlob,                  /* OUT: Blob data in malloc'd buffer */
+  int *pnBlob,                    /* OUT: Size of blob data */
+  int *pnLoad                     /* OUT: Bytes actually loaded */
+){
+  int rc;                         /* Return code */
+
+  /* pnBlob must be non-NULL. paBlob may be NULL or non-NULL. */
+  assert( pnBlob );
+
+  if( p->pSegments ){
+    rc = sqlite3_blob_reopen(p->pSegments, iBlockid);
+  }else{
+    if( 0==p->zSegmentsTbl ){
+      p->zSegmentsTbl = sqlite3_mprintf("%s_segments", p->zName);
+      if( 0==p->zSegmentsTbl ) return SQLITE_NOMEM;
+    }
+    rc = sqlite3_blob_open(
+       p->db, p->zDb, p->zSegmentsTbl, "block", iBlockid, 0, &p->pSegments
+    );
+  }
+
+  if( rc==SQLITE_OK ){
+    int nByte = sqlite3_blob_bytes(p->pSegments);
+    *pnBlob = nByte;
+    if( paBlob ){
+      char *aByte = sqlite3_malloc(nByte + FTS3_NODE_PADDING);
+      if( !aByte ){
+        rc = SQLITE_NOMEM;
+      }else{
+        if( pnLoad && nByte>(FTS3_NODE_CHUNK_THRESHOLD) ){
+          nByte = FTS3_NODE_CHUNKSIZE;
+          *pnLoad = nByte;
+        }
+        rc = sqlite3_blob_read(p->pSegments, aByte, nByte, 0);
+        memset(&aByte[nByte], 0, FTS3_NODE_PADDING);
+        if( rc!=SQLITE_OK ){
+          sqlite3_free(aByte);
+          aByte = 0;
+        }
+      }
+      *paBlob = aByte;
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Close the blob handle at p->pSegments, if it is open. See comments above
+** the sqlite3Fts3ReadBlock() function for details.
+*/
+SQLITE_PRIVATE void sqlite3Fts3SegmentsClose(Fts3Table *p){
+  sqlite3_blob_close(p->pSegments);
+  p->pSegments = 0;
+}
+    
+static int fts3SegReaderIncrRead(Fts3SegReader *pReader){
+  int nRead;                      /* Number of bytes to read */
+  int rc;                         /* Return code */
+
+  nRead = MIN(pReader->nNode - pReader->nPopulate, FTS3_NODE_CHUNKSIZE);
+  rc = sqlite3_blob_read(
+      pReader->pBlob, 
+      &pReader->aNode[pReader->nPopulate],
+      nRead,
+      pReader->nPopulate
+  );
+
+  if( rc==SQLITE_OK ){
+    pReader->nPopulate += nRead;
+    memset(&pReader->aNode[pReader->nPopulate], 0, FTS3_NODE_PADDING);
+    if( pReader->nPopulate==pReader->nNode ){
+      sqlite3_blob_close(pReader->pBlob);
+      pReader->pBlob = 0;
+      pReader->nPopulate = 0;
+    }
+  }
+  return rc;
+}
+
+static int fts3SegReaderRequire(Fts3SegReader *pReader, char *pFrom, int nByte){
+  int rc = SQLITE_OK;
+  assert( !pReader->pBlob 
+       || (pFrom>=pReader->aNode && pFrom<&pReader->aNode[pReader->nNode])
+  );
+  while( pReader->pBlob && rc==SQLITE_OK 
+     &&  (pFrom - pReader->aNode + nByte)>pReader->nPopulate
+  ){
+    rc = fts3SegReaderIncrRead(pReader);
+  }
+  return rc;
+}
+
+/*
+** Set an Fts3SegReader cursor to point at EOF.
+*/
+static void fts3SegReaderSetEof(Fts3SegReader *pSeg){
+  if( !fts3SegReaderIsRootOnly(pSeg) ){
+    sqlite3_free(pSeg->aNode);
+    sqlite3_blob_close(pSeg->pBlob);
+    pSeg->pBlob = 0;
+  }
+  pSeg->aNode = 0;
+}
+
+/*
+** Move the iterator passed as the first argument to the next term in the
+** segment. If successful, SQLITE_OK is returned. If there is no next term,
+** SQLITE_DONE. Otherwise, an SQLite error code.
+*/
+static int fts3SegReaderNext(
+  Fts3Table *p, 
+  Fts3SegReader *pReader,
+  int bIncr
+){
+  int rc;                         /* Return code of various sub-routines */
+  char *pNext;                    /* Cursor variable */
+  int nPrefix;                    /* Number of bytes in term prefix */
+  int nSuffix;                    /* Number of bytes in term suffix */
+
+  if( !pReader->aDoclist ){
+    pNext = pReader->aNode;
+  }else{
+    pNext = &pReader->aDoclist[pReader->nDoclist];
+  }
+
+  if( !pNext || pNext>=&pReader->aNode[pReader->nNode] ){
+
+    if( fts3SegReaderIsPending(pReader) ){
+      Fts3HashElem *pElem = *(pReader->ppNextElem);
+      sqlite3_free(pReader->aNode);
+      pReader->aNode = 0;
+      if( pElem ){
+        char *aCopy;
+        PendingList *pList = (PendingList *)fts3HashData(pElem);
+        int nCopy = pList->nData+1;
+        pReader->zTerm = (char *)fts3HashKey(pElem);
+        pReader->nTerm = fts3HashKeysize(pElem);
+        aCopy = (char*)sqlite3_malloc(nCopy);
+        if( !aCopy ) return SQLITE_NOMEM;
+        memcpy(aCopy, pList->aData, nCopy);
+        pReader->nNode = pReader->nDoclist = nCopy;
+        pReader->aNode = pReader->aDoclist = aCopy;
+        pReader->ppNextElem++;
+        assert( pReader->aNode );
+      }
+      return SQLITE_OK;
+    }
+
+    fts3SegReaderSetEof(pReader);
+
+    /* If iCurrentBlock>=iLeafEndBlock, this is an EOF condition. All leaf 
+    ** blocks have already been traversed.  */
+    assert( pReader->iCurrentBlock<=pReader->iLeafEndBlock );
+    if( pReader->iCurrentBlock>=pReader->iLeafEndBlock ){
+      return SQLITE_OK;
+    }
+
+    rc = sqlite3Fts3ReadBlock(
+        p, ++pReader->iCurrentBlock, &pReader->aNode, &pReader->nNode, 
+        (bIncr ? &pReader->nPopulate : 0)
+    );
+    if( rc!=SQLITE_OK ) return rc;
+    assert( pReader->pBlob==0 );
+    if( bIncr && pReader->nPopulate<pReader->nNode ){
+      pReader->pBlob = p->pSegments;
+      p->pSegments = 0;
+    }
+    pNext = pReader->aNode;
+  }
+
+  assert( !fts3SegReaderIsPending(pReader) );
+
+  rc = fts3SegReaderRequire(pReader, pNext, FTS3_VARINT_MAX*2);
+  if( rc!=SQLITE_OK ) return rc;
+  
+  /* Because of the FTS3_NODE_PADDING bytes of padding, the following is 
+  ** safe (no risk of overread) even if the node data is corrupted. */
+  pNext += fts3GetVarint32(pNext, &nPrefix);
+  pNext += fts3GetVarint32(pNext, &nSuffix);
+  if( nPrefix<0 || nSuffix<=0 
+   || &pNext[nSuffix]>&pReader->aNode[pReader->nNode] 
+  ){
+    return FTS_CORRUPT_VTAB;
+  }
+
+  if( nPrefix+nSuffix>pReader->nTermAlloc ){
+    int nNew = (nPrefix+nSuffix)*2;
+    char *zNew = sqlite3_realloc(pReader->zTerm, nNew);
+    if( !zNew ){
+      return SQLITE_NOMEM;
+    }
+    pReader->zTerm = zNew;
+    pReader->nTermAlloc = nNew;
+  }
+
+  rc = fts3SegReaderRequire(pReader, pNext, nSuffix+FTS3_VARINT_MAX);
+  if( rc!=SQLITE_OK ) return rc;
+
+  memcpy(&pReader->zTerm[nPrefix], pNext, nSuffix);
+  pReader->nTerm = nPrefix+nSuffix;
+  pNext += nSuffix;
+  pNext += fts3GetVarint32(pNext, &pReader->nDoclist);
+  pReader->aDoclist = pNext;
+  pReader->pOffsetList = 0;
+
+  /* Check that the doclist does not appear to extend past the end of the
+  ** b-tree node. And that the final byte of the doclist is 0x00. If either 
+  ** of these statements is untrue, then the data structure is corrupt.
+  */
+  if( &pReader->aDoclist[pReader->nDoclist]>&pReader->aNode[pReader->nNode] 
+   || (pReader->nPopulate==0 && pReader->aDoclist[pReader->nDoclist-1])
+  ){
+    return FTS_CORRUPT_VTAB;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Set the SegReader to point to the first docid in the doclist associated
+** with the current term.
+*/
+static int fts3SegReaderFirstDocid(Fts3Table *pTab, Fts3SegReader *pReader){
+  int rc = SQLITE_OK;
+  assert( pReader->aDoclist );
+  assert( !pReader->pOffsetList );
+  if( pTab->bDescIdx && fts3SegReaderIsPending(pReader) ){
+    u8 bEof = 0;
+    pReader->iDocid = 0;
+    pReader->nOffsetList = 0;
+    sqlite3Fts3DoclistPrev(0,
+        pReader->aDoclist, pReader->nDoclist, &pReader->pOffsetList, 
+        &pReader->iDocid, &pReader->nOffsetList, &bEof
+    );
+  }else{
+    rc = fts3SegReaderRequire(pReader, pReader->aDoclist, FTS3_VARINT_MAX);
+    if( rc==SQLITE_OK ){
+      int n = sqlite3Fts3GetVarint(pReader->aDoclist, &pReader->iDocid);
+      pReader->pOffsetList = &pReader->aDoclist[n];
+    }
+  }
+  return rc;
+}
+
+/*
+** Advance the SegReader to point to the next docid in the doclist
+** associated with the current term.
+** 
+** If arguments ppOffsetList and pnOffsetList are not NULL, then 
+** *ppOffsetList is set to point to the first column-offset list
+** in the doclist entry (i.e. immediately past the docid varint).
+** *pnOffsetList is set to the length of the set of column-offset
+** lists, not including the nul-terminator byte. For example:
+*/
+static int fts3SegReaderNextDocid(
+  Fts3Table *pTab,
+  Fts3SegReader *pReader,         /* Reader to advance to next docid */
+  char **ppOffsetList,            /* OUT: Pointer to current position-list */
+  int *pnOffsetList               /* OUT: Length of *ppOffsetList in bytes */
+){
+  int rc = SQLITE_OK;
+  char *p = pReader->pOffsetList;
+  char c = 0;
+
+  assert( p );
+
+  if( pTab->bDescIdx && fts3SegReaderIsPending(pReader) ){
+    /* A pending-terms seg-reader for an FTS4 table that uses order=desc.
+    ** Pending-terms doclists are always built up in ascending order, so
+    ** we have to iterate through them backwards here. */
+    u8 bEof = 0;
+    if( ppOffsetList ){
+      *ppOffsetList = pReader->pOffsetList;
+      *pnOffsetList = pReader->nOffsetList - 1;
+    }
+    sqlite3Fts3DoclistPrev(0,
+        pReader->aDoclist, pReader->nDoclist, &p, &pReader->iDocid,
+        &pReader->nOffsetList, &bEof
+    );
+    if( bEof ){
+      pReader->pOffsetList = 0;
+    }else{
+      pReader->pOffsetList = p;
+    }
+  }else{
+    char *pEnd = &pReader->aDoclist[pReader->nDoclist];
+
+    /* Pointer p currently points at the first byte of an offset list. The
+    ** following block advances it to point one byte past the end of
+    ** the same offset list. */
+    while( 1 ){
+  
+      /* The following line of code (and the "p++" below the while() loop) is
+      ** normally all that is required to move pointer p to the desired 
+      ** position. The exception is if this node is being loaded from disk
+      ** incrementally and pointer "p" now points to the first byte past
+      ** the populated part of pReader->aNode[].
+      */
+      while( *p | c ) c = *p++ & 0x80;
+      assert( *p==0 );
+  
+      if( pReader->pBlob==0 || p<&pReader->aNode[pReader->nPopulate] ) break;
+      rc = fts3SegReaderIncrRead(pReader);
+      if( rc!=SQLITE_OK ) return rc;
+    }
+    p++;
+  
+    /* If required, populate the output variables with a pointer to and the
+    ** size of the previous offset-list.
+    */
+    if( ppOffsetList ){
+      *ppOffsetList = pReader->pOffsetList;
+      *pnOffsetList = (int)(p - pReader->pOffsetList - 1);
+    }
+
+    /* List may have been edited in place by fts3EvalNearTrim() */
+    while( p<pEnd && *p==0 ) p++;
+  
+    /* If there are no more entries in the doclist, set pOffsetList to
+    ** NULL. Otherwise, set Fts3SegReader.iDocid to the next docid and
+    ** Fts3SegReader.pOffsetList to point to the next offset list before
+    ** returning.
+    */
+    if( p>=pEnd ){
+      pReader->pOffsetList = 0;
+    }else{
+      rc = fts3SegReaderRequire(pReader, p, FTS3_VARINT_MAX);
+      if( rc==SQLITE_OK ){
+        sqlite3_int64 iDelta;
+        pReader->pOffsetList = p + sqlite3Fts3GetVarint(p, &iDelta);
+        if( pTab->bDescIdx ){
+          pReader->iDocid -= iDelta;
+        }else{
+          pReader->iDocid += iDelta;
+        }
+      }
+    }
+  }
+
+  return SQLITE_OK;
+}
+
+
+SQLITE_PRIVATE int sqlite3Fts3MsrOvfl(
+  Fts3Cursor *pCsr, 
+  Fts3MultiSegReader *pMsr,
+  int *pnOvfl
+){
+  Fts3Table *p = (Fts3Table*)pCsr->base.pVtab;
+  int nOvfl = 0;
+  int ii;
+  int rc = SQLITE_OK;
+  int pgsz = p->nPgsz;
+
+  assert( p->bFts4 );
+  assert( pgsz>0 );
+
+  for(ii=0; rc==SQLITE_OK && ii<pMsr->nSegment; ii++){
+    Fts3SegReader *pReader = pMsr->apSegment[ii];
+    if( !fts3SegReaderIsPending(pReader) 
+     && !fts3SegReaderIsRootOnly(pReader) 
+    ){
+      sqlite3_int64 jj;
+      for(jj=pReader->iStartBlock; jj<=pReader->iLeafEndBlock; jj++){
+        int nBlob;
+        rc = sqlite3Fts3ReadBlock(p, jj, 0, &nBlob, 0);
+        if( rc!=SQLITE_OK ) break;
+        if( (nBlob+35)>pgsz ){
+          nOvfl += (nBlob + 34)/pgsz;
+        }
+      }
+    }
+  }
+  *pnOvfl = nOvfl;
+  return rc;
+}
+
+/*
+** Free all allocations associated with the iterator passed as the 
+** second argument.
+*/
+SQLITE_PRIVATE void sqlite3Fts3SegReaderFree(Fts3SegReader *pReader){
+  if( pReader ){
+    if( !fts3SegReaderIsPending(pReader) ){
+      sqlite3_free(pReader->zTerm);
+    }
+    if( !fts3SegReaderIsRootOnly(pReader) ){
+      sqlite3_free(pReader->aNode);
+    }
+    sqlite3_blob_close(pReader->pBlob);
+  }
+  sqlite3_free(pReader);
+}
+
+/*
+** Allocate a new SegReader object.
+*/
+SQLITE_PRIVATE int sqlite3Fts3SegReaderNew(
+  int iAge,                       /* Segment "age". */
+  int bLookup,                    /* True for a lookup only */
+  sqlite3_int64 iStartLeaf,       /* First leaf to traverse */
+  sqlite3_int64 iEndLeaf,         /* Final leaf to traverse */
+  sqlite3_int64 iEndBlock,        /* Final block of segment */
+  const char *zRoot,              /* Buffer containing root node */
+  int nRoot,                      /* Size of buffer containing root node */
+  Fts3SegReader **ppReader        /* OUT: Allocated Fts3SegReader */
+){
+  Fts3SegReader *pReader;         /* Newly allocated SegReader object */
+  int nExtra = 0;                 /* Bytes to allocate segment root node */
+
+  assert( iStartLeaf<=iEndLeaf );
+  if( iStartLeaf==0 ){
+    nExtra = nRoot + FTS3_NODE_PADDING;
+  }
+
+  pReader = (Fts3SegReader *)sqlite3_malloc(sizeof(Fts3SegReader) + nExtra);
+  if( !pReader ){
+    return SQLITE_NOMEM;
+  }
+  memset(pReader, 0, sizeof(Fts3SegReader));
+  pReader->iIdx = iAge;
+  pReader->bLookup = bLookup!=0;
+  pReader->iStartBlock = iStartLeaf;
+  pReader->iLeafEndBlock = iEndLeaf;
+  pReader->iEndBlock = iEndBlock;
+
+  if( nExtra ){
+    /* The entire segment is stored in the root node. */
+    pReader->aNode = (char *)&pReader[1];
+    pReader->rootOnly = 1;
+    pReader->nNode = nRoot;
+    memcpy(pReader->aNode, zRoot, nRoot);
+    memset(&pReader->aNode[nRoot], 0, FTS3_NODE_PADDING);
+  }else{
+    pReader->iCurrentBlock = iStartLeaf-1;
+  }
+  *ppReader = pReader;
+  return SQLITE_OK;
+}
+
+/*
+** This is a comparison function used as a qsort() callback when sorting
+** an array of pending terms by term. This occurs as part of flushing
+** the contents of the pending-terms hash table to the database.
+*/
+static int SQLITE_CDECL fts3CompareElemByTerm(
+  const void *lhs,
+  const void *rhs
+){
+  char *z1 = fts3HashKey(*(Fts3HashElem **)lhs);
+  char *z2 = fts3HashKey(*(Fts3HashElem **)rhs);
+  int n1 = fts3HashKeysize(*(Fts3HashElem **)lhs);
+  int n2 = fts3HashKeysize(*(Fts3HashElem **)rhs);
+
+  int n = (n1<n2 ? n1 : n2);
+  int c = memcmp(z1, z2, n);
+  if( c==0 ){
+    c = n1 - n2;
+  }
+  return c;
+}
+
+/*
+** This function is used to allocate an Fts3SegReader that iterates through
+** a subset of the terms stored in the Fts3Table.pendingTerms array.
+**
+** If the isPrefixIter parameter is zero, then the returned SegReader iterates
+** through each term in the pending-terms table. Or, if isPrefixIter is
+** non-zero, it iterates through each term and its prefixes. For example, if
+** the pending terms hash table contains the terms "sqlite", "mysql" and
+** "firebird", then the iterator visits the following 'terms' (in the order
+** shown):
+**
+**   f fi fir fire fireb firebi firebir firebird
+**   m my mys mysq mysql
+**   s sq sql sqli sqlit sqlite
+**
+** Whereas if isPrefixIter is zero, the terms visited are:
+**
+**   firebird mysql sqlite
+*/
+SQLITE_PRIVATE int sqlite3Fts3SegReaderPending(
+  Fts3Table *p,                   /* Virtual table handle */
+  int iIndex,                     /* Index for p->aIndex */
+  const char *zTerm,              /* Term to search for */
+  int nTerm,                      /* Size of buffer zTerm */
+  int bPrefix,                    /* True for a prefix iterator */
+  Fts3SegReader **ppReader        /* OUT: SegReader for pending-terms */
+){
+  Fts3SegReader *pReader = 0;     /* Fts3SegReader object to return */
+  Fts3HashElem *pE;               /* Iterator variable */
+  Fts3HashElem **aElem = 0;       /* Array of term hash entries to scan */
+  int nElem = 0;                  /* Size of array at aElem */
+  int rc = SQLITE_OK;             /* Return Code */
+  Fts3Hash *pHash;
+
+  pHash = &p->aIndex[iIndex].hPending;
+  if( bPrefix ){
+    int nAlloc = 0;               /* Size of allocated array at aElem */
+
+    for(pE=fts3HashFirst(pHash); pE; pE=fts3HashNext(pE)){
+      char *zKey = (char *)fts3HashKey(pE);
+      int nKey = fts3HashKeysize(pE);
+      if( nTerm==0 || (nKey>=nTerm && 0==memcmp(zKey, zTerm, nTerm)) ){
+        if( nElem==nAlloc ){
+          Fts3HashElem **aElem2;
+          nAlloc += 16;
+          aElem2 = (Fts3HashElem **)sqlite3_realloc(
+              aElem, nAlloc*sizeof(Fts3HashElem *)
+          );
+          if( !aElem2 ){
+            rc = SQLITE_NOMEM;
+            nElem = 0;
+            break;
+          }
+          aElem = aElem2;
+        }
+
+        aElem[nElem++] = pE;
+      }
+    }
+
+    /* If more than one term matches the prefix, sort the Fts3HashElem
+    ** objects in term order using qsort(). This uses the same comparison
+    ** callback as is used when flushing terms to disk.
+    */
+    if( nElem>1 ){
+      qsort(aElem, nElem, sizeof(Fts3HashElem *), fts3CompareElemByTerm);
+    }
+
+  }else{
+    /* The query is a simple term lookup that matches at most one term in
+    ** the index. All that is required is a straight hash-lookup. 
+    **
+    ** Because the stack address of pE may be accessed via the aElem pointer
+    ** below, the "Fts3HashElem *pE" must be declared so that it is valid
+    ** within this entire function, not just this "else{...}" block.
+    */
+    pE = fts3HashFindElem(pHash, zTerm, nTerm);
+    if( pE ){
+      aElem = &pE;
+      nElem = 1;
+    }
+  }
+
+  if( nElem>0 ){
+    int nByte = sizeof(Fts3SegReader) + (nElem+1)*sizeof(Fts3HashElem *);
+    pReader = (Fts3SegReader *)sqlite3_malloc(nByte);
+    if( !pReader ){
+      rc = SQLITE_NOMEM;
+    }else{
+      memset(pReader, 0, nByte);
+      pReader->iIdx = 0x7FFFFFFF;
+      pReader->ppNextElem = (Fts3HashElem **)&pReader[1];
+      memcpy(pReader->ppNextElem, aElem, nElem*sizeof(Fts3HashElem *));
+    }
+  }
+
+  if( bPrefix ){
+    sqlite3_free(aElem);
+  }
+  *ppReader = pReader;
+  return rc;
+}
+
+/*
+** Compare the entries pointed to by two Fts3SegReader structures. 
+** Comparison is as follows:
+**
+**   1) EOF is greater than not EOF.
+**
+**   2) The current terms (if any) are compared using memcmp(). If one
+**      term is a prefix of another, the longer term is considered the
+**      larger.
+**
+**   3) By segment age. An older segment is considered larger.
+*/
+static int fts3SegReaderCmp(Fts3SegReader *pLhs, Fts3SegReader *pRhs){
+  int rc;
+  if( pLhs->aNode && pRhs->aNode ){
+    int rc2 = pLhs->nTerm - pRhs->nTerm;
+    if( rc2<0 ){
+      rc = memcmp(pLhs->zTerm, pRhs->zTerm, pLhs->nTerm);
+    }else{
+      rc = memcmp(pLhs->zTerm, pRhs->zTerm, pRhs->nTerm);
+    }
+    if( rc==0 ){
+      rc = rc2;
+    }
+  }else{
+    rc = (pLhs->aNode==0) - (pRhs->aNode==0);
+  }
+  if( rc==0 ){
+    rc = pRhs->iIdx - pLhs->iIdx;
+  }
+  assert( rc!=0 );
+  return rc;
+}
+
+/*
+** A different comparison function for SegReader structures. In this
+** version, it is assumed that each SegReader points to an entry in
+** a doclist for identical terms. Comparison is made as follows:
+**
+**   1) EOF (end of doclist in this case) is greater than not EOF.
+**
+**   2) By current docid.
+**
+**   3) By segment age. An older segment is considered larger.
+*/
+static int fts3SegReaderDoclistCmp(Fts3SegReader *pLhs, Fts3SegReader *pRhs){
+  int rc = (pLhs->pOffsetList==0)-(pRhs->pOffsetList==0);
+  if( rc==0 ){
+    if( pLhs->iDocid==pRhs->iDocid ){
+      rc = pRhs->iIdx - pLhs->iIdx;
+    }else{
+      rc = (pLhs->iDocid > pRhs->iDocid) ? 1 : -1;
+    }
+  }
+  assert( pLhs->aNode && pRhs->aNode );
+  return rc;
+}
+static int fts3SegReaderDoclistCmpRev(Fts3SegReader *pLhs, Fts3SegReader *pRhs){
+  int rc = (pLhs->pOffsetList==0)-(pRhs->pOffsetList==0);
+  if( rc==0 ){
+    if( pLhs->iDocid==pRhs->iDocid ){
+      rc = pRhs->iIdx - pLhs->iIdx;
+    }else{
+      rc = (pLhs->iDocid < pRhs->iDocid) ? 1 : -1;
+    }
+  }
+  assert( pLhs->aNode && pRhs->aNode );
+  return rc;
+}
+
+/*
+** Compare the term that the Fts3SegReader object passed as the first argument
+** points to with the term specified by arguments zTerm and nTerm. 
+**
+** If the pSeg iterator is already at EOF, return 0. Otherwise, return
+** -ve if the pSeg term is less than zTerm/nTerm, 0 if the two terms are
+** equal, or +ve if the pSeg term is greater than zTerm/nTerm.
+*/
+static int fts3SegReaderTermCmp(
+  Fts3SegReader *pSeg,            /* Segment reader object */
+  const char *zTerm,              /* Term to compare to */
+  int nTerm                       /* Size of term zTerm in bytes */
+){
+  int res = 0;
+  if( pSeg->aNode ){
+    if( pSeg->nTerm>nTerm ){
+      res = memcmp(pSeg->zTerm, zTerm, nTerm);
+    }else{
+      res = memcmp(pSeg->zTerm, zTerm, pSeg->nTerm);
+    }
+    if( res==0 ){
+      res = pSeg->nTerm-nTerm;
+    }
+  }
+  return res;
+}
+
+/*
+** Argument apSegment is an array of nSegment elements. It is known that
+** the final (nSegment-nSuspect) members are already in sorted order
+** (according to the comparison function provided). This function shuffles
+** the array around until all entries are in sorted order.
+*/
+static void fts3SegReaderSort(
+  Fts3SegReader **apSegment,                     /* Array to sort entries of */
+  int nSegment,                                  /* Size of apSegment array */
+  int nSuspect,                                  /* Unsorted entry count */
+  int (*xCmp)(Fts3SegReader *, Fts3SegReader *)  /* Comparison function */
+){
+  int i;                          /* Iterator variable */
+
+  assert( nSuspect<=nSegment );
+
+  if( nSuspect==nSegment ) nSuspect--;
+  for(i=nSuspect-1; i>=0; i--){
+    int j;
+    for(j=i; j<(nSegment-1); j++){
+      Fts3SegReader *pTmp;
+      if( xCmp(apSegment[j], apSegment[j+1])<0 ) break;
+      pTmp = apSegment[j+1];
+      apSegment[j+1] = apSegment[j];
+      apSegment[j] = pTmp;
+    }
+  }
+
+#ifndef NDEBUG
+  /* Check that the list really is sorted now. */
+  for(i=0; i<(nSuspect-1); i++){
+    assert( xCmp(apSegment[i], apSegment[i+1])<0 );
+  }
+#endif
+}
+
+/* 
+** Insert a record into the %_segments table.
+*/
+static int fts3WriteSegment(
+  Fts3Table *p,                   /* Virtual table handle */
+  sqlite3_int64 iBlock,           /* Block id for new block */
+  char *z,                        /* Pointer to buffer containing block data */
+  int n                           /* Size of buffer z in bytes */
+){
+  sqlite3_stmt *pStmt;
+  int rc = fts3SqlStmt(p, SQL_INSERT_SEGMENTS, &pStmt, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int64(pStmt, 1, iBlock);
+    sqlite3_bind_blob(pStmt, 2, z, n, SQLITE_STATIC);
+    sqlite3_step(pStmt);
+    rc = sqlite3_reset(pStmt);
+  }
+  return rc;
+}
+
+/*
+** Find the largest relative level number in the table. If successful, set
+** *pnMax to this value and return SQLITE_OK. Otherwise, if an error occurs,
+** set *pnMax to zero and return an SQLite error code.
+*/
+SQLITE_PRIVATE int sqlite3Fts3MaxLevel(Fts3Table *p, int *pnMax){
+  int rc;
+  int mxLevel = 0;
+  sqlite3_stmt *pStmt = 0;
+
+  rc = fts3SqlStmt(p, SQL_SELECT_MXLEVEL, &pStmt, 0);
+  if( rc==SQLITE_OK ){
+    if( SQLITE_ROW==sqlite3_step(pStmt) ){
+      mxLevel = sqlite3_column_int(pStmt, 0);
+    }
+    rc = sqlite3_reset(pStmt);
+  }
+  *pnMax = mxLevel;
+  return rc;
+}
+
+/* 
+** Insert a record into the %_segdir table.
+*/
+static int fts3WriteSegdir(
+  Fts3Table *p,                   /* Virtual table handle */
+  sqlite3_int64 iLevel,           /* Value for "level" field (absolute level) */
+  int iIdx,                       /* Value for "idx" field */
+  sqlite3_int64 iStartBlock,      /* Value for "start_block" field */
+  sqlite3_int64 iLeafEndBlock,    /* Value for "leaves_end_block" field */
+  sqlite3_int64 iEndBlock,        /* Value for "end_block" field */
+  sqlite3_int64 nLeafData,        /* Bytes of leaf data in segment */
+  char *zRoot,                    /* Blob value for "root" field */
+  int nRoot                       /* Number of bytes in buffer zRoot */
+){
+  sqlite3_stmt *pStmt;
+  int rc = fts3SqlStmt(p, SQL_INSERT_SEGDIR, &pStmt, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int64(pStmt, 1, iLevel);
+    sqlite3_bind_int(pStmt, 2, iIdx);
+    sqlite3_bind_int64(pStmt, 3, iStartBlock);
+    sqlite3_bind_int64(pStmt, 4, iLeafEndBlock);
+    if( nLeafData==0 ){
+      sqlite3_bind_int64(pStmt, 5, iEndBlock);
+    }else{
+      char *zEnd = sqlite3_mprintf("%lld %lld", iEndBlock, nLeafData);
+      if( !zEnd ) return SQLITE_NOMEM;
+      sqlite3_bind_text(pStmt, 5, zEnd, -1, sqlite3_free);
+    }
+    sqlite3_bind_blob(pStmt, 6, zRoot, nRoot, SQLITE_STATIC);
+    sqlite3_step(pStmt);
+    rc = sqlite3_reset(pStmt);
+  }
+  return rc;
+}
+
+/*
+** Return the size of the common prefix (if any) shared by zPrev and
+** zNext, in bytes. For example, 
+**
+**   fts3PrefixCompress("abc", 3, "abcdef", 6)   // returns 3
+**   fts3PrefixCompress("abX", 3, "abcdef", 6)   // returns 2
+**   fts3PrefixCompress("abX", 3, "Xbcdef", 6)   // returns 0
+*/
+static int fts3PrefixCompress(
+  const char *zPrev,              /* Buffer containing previous term */
+  int nPrev,                      /* Size of buffer zPrev in bytes */
+  const char *zNext,              /* Buffer containing next term */
+  int nNext                       /* Size of buffer zNext in bytes */
+){
+  int n;
+  UNUSED_PARAMETER(nNext);
+  for(n=0; n<nPrev && zPrev[n]==zNext[n]; n++);
+  return n;
+}
+
+/*
+** Add term zTerm to the SegmentNode. It is guaranteed that zTerm is larger
+** (according to memcmp) than the previous term.
+*/
+static int fts3NodeAddTerm(
+  Fts3Table *p,                   /* Virtual table handle */
+  SegmentNode **ppTree,           /* IN/OUT: SegmentNode handle */ 
+  int isCopyTerm,                 /* True if zTerm/nTerm is transient */
+  const char *zTerm,              /* Pointer to buffer containing term */
+  int nTerm                       /* Size of term in bytes */
+){
+  SegmentNode *pTree = *ppTree;
+  int rc;
+  SegmentNode *pNew;
+
+  /* First try to append the term to the current node. Return early if 
+  ** this is possible.
+  */
+  if( pTree ){
+    int nData = pTree->nData;     /* Current size of node in bytes */
+    int nReq = nData;             /* Required space after adding zTerm */
+    int nPrefix;                  /* Number of bytes of prefix compression */
+    int nSuffix;                  /* Suffix length */
+
+    nPrefix = fts3PrefixCompress(pTree->zTerm, pTree->nTerm, zTerm, nTerm);
+    nSuffix = nTerm-nPrefix;
+
+    nReq += sqlite3Fts3VarintLen(nPrefix)+sqlite3Fts3VarintLen(nSuffix)+nSuffix;
+    if( nReq<=p->nNodeSize || !pTree->zTerm ){
+
+      if( nReq>p->nNodeSize ){
+        /* An unusual case: this is the first term to be added to the node
+        ** and the static node buffer (p->nNodeSize bytes) is not large
+        ** enough. Use a separately malloced buffer instead This wastes
+        ** p->nNodeSize bytes, but since this scenario only comes about when
+        ** the database contain two terms that share a prefix of almost 2KB, 
+        ** this is not expected to be a serious problem. 
+        */
+        assert( pTree->aData==(char *)&pTree[1] );
+        pTree->aData = (char *)sqlite3_malloc(nReq);
+        if( !pTree->aData ){
+          return SQLITE_NOMEM;
+        }
+      }
+
+      if( pTree->zTerm ){
+        /* There is no prefix-length field for first term in a node */
+        nData += sqlite3Fts3PutVarint(&pTree->aData[nData], nPrefix);
+      }
+
+      nData += sqlite3Fts3PutVarint(&pTree->aData[nData], nSuffix);
+      memcpy(&pTree->aData[nData], &zTerm[nPrefix], nSuffix);
+      pTree->nData = nData + nSuffix;
+      pTree->nEntry++;
+
+      if( isCopyTerm ){
+        if( pTree->nMalloc<nTerm ){
+          char *zNew = sqlite3_realloc(pTree->zMalloc, nTerm*2);
+          if( !zNew ){
+            return SQLITE_NOMEM;
+          }
+          pTree->nMalloc = nTerm*2;
+          pTree->zMalloc = zNew;
+        }
+        pTree->zTerm = pTree->zMalloc;
+        memcpy(pTree->zTerm, zTerm, nTerm);
+        pTree->nTerm = nTerm;
+      }else{
+        pTree->zTerm = (char *)zTerm;
+        pTree->nTerm = nTerm;
+      }
+      return SQLITE_OK;
+    }
+  }
+
+  /* If control flows to here, it was not possible to append zTerm to the
+  ** current node. Create a new node (a right-sibling of the current node).
+  ** If this is the first node in the tree, the term is added to it.
+  **
+  ** Otherwise, the term is not added to the new node, it is left empty for
+  ** now. Instead, the term is inserted into the parent of pTree. If pTree 
+  ** has no parent, one is created here.
+  */
+  pNew = (SegmentNode *)sqlite3_malloc(sizeof(SegmentNode) + p->nNodeSize);
+  if( !pNew ){
+    return SQLITE_NOMEM;
+  }
+  memset(pNew, 0, sizeof(SegmentNode));
+  pNew->nData = 1 + FTS3_VARINT_MAX;
+  pNew->aData = (char *)&pNew[1];
+
+  if( pTree ){
+    SegmentNode *pParent = pTree->pParent;
+    rc = fts3NodeAddTerm(p, &pParent, isCopyTerm, zTerm, nTerm);
+    if( pTree->pParent==0 ){
+      pTree->pParent = pParent;
+    }
+    pTree->pRight = pNew;
+    pNew->pLeftmost = pTree->pLeftmost;
+    pNew->pParent = pParent;
+    pNew->zMalloc = pTree->zMalloc;
+    pNew->nMalloc = pTree->nMalloc;
+    pTree->zMalloc = 0;
+  }else{
+    pNew->pLeftmost = pNew;
+    rc = fts3NodeAddTerm(p, &pNew, isCopyTerm, zTerm, nTerm); 
+  }
+
+  *ppTree = pNew;
+  return rc;
+}
+
+/*
+** Helper function for fts3NodeWrite().
+*/
+static int fts3TreeFinishNode(
+  SegmentNode *pTree, 
+  int iHeight, 
+  sqlite3_int64 iLeftChild
+){
+  int nStart;
+  assert( iHeight>=1 && iHeight<128 );
+  nStart = FTS3_VARINT_MAX - sqlite3Fts3VarintLen(iLeftChild);
+  pTree->aData[nStart] = (char)iHeight;
+  sqlite3Fts3PutVarint(&pTree->aData[nStart+1], iLeftChild);
+  return nStart;
+}
+
+/*
+** Write the buffer for the segment node pTree and all of its peers to the
+** database. Then call this function recursively to write the parent of 
+** pTree and its peers to the database. 
+**
+** Except, if pTree is a root node, do not write it to the database. Instead,
+** set output variables *paRoot and *pnRoot to contain the root node.
+**
+** If successful, SQLITE_OK is returned and output variable *piLast is
+** set to the largest blockid written to the database (or zero if no
+** blocks were written to the db). Otherwise, an SQLite error code is 
+** returned.
+*/
+static int fts3NodeWrite(
+  Fts3Table *p,                   /* Virtual table handle */
+  SegmentNode *pTree,             /* SegmentNode handle */
+  int iHeight,                    /* Height of this node in tree */
+  sqlite3_int64 iLeaf,            /* Block id of first leaf node */
+  sqlite3_int64 iFree,            /* Block id of next free slot in %_segments */
+  sqlite3_int64 *piLast,          /* OUT: Block id of last entry written */
+  char **paRoot,                  /* OUT: Data for root node */
+  int *pnRoot                     /* OUT: Size of root node in bytes */
+){
+  int rc = SQLITE_OK;
+
+  if( !pTree->pParent ){
+    /* Root node of the tree. */
+    int nStart = fts3TreeFinishNode(pTree, iHeight, iLeaf);
+    *piLast = iFree-1;
+    *pnRoot = pTree->nData - nStart;
+    *paRoot = &pTree->aData[nStart];
+  }else{
+    SegmentNode *pIter;
+    sqlite3_int64 iNextFree = iFree;
+    sqlite3_int64 iNextLeaf = iLeaf;
+    for(pIter=pTree->pLeftmost; pIter && rc==SQLITE_OK; pIter=pIter->pRight){
+      int nStart = fts3TreeFinishNode(pIter, iHeight, iNextLeaf);
+      int nWrite = pIter->nData - nStart;
+  
+      rc = fts3WriteSegment(p, iNextFree, &pIter->aData[nStart], nWrite);
+      iNextFree++;
+      iNextLeaf += (pIter->nEntry+1);
+    }
+    if( rc==SQLITE_OK ){
+      assert( iNextLeaf==iFree );
+      rc = fts3NodeWrite(
+          p, pTree->pParent, iHeight+1, iFree, iNextFree, piLast, paRoot, pnRoot
+      );
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Free all memory allocations associated with the tree pTree.
+*/
+static void fts3NodeFree(SegmentNode *pTree){
+  if( pTree ){
+    SegmentNode *p = pTree->pLeftmost;
+    fts3NodeFree(p->pParent);
+    while( p ){
+      SegmentNode *pRight = p->pRight;
+      if( p->aData!=(char *)&p[1] ){
+        sqlite3_free(p->aData);
+      }
+      assert( pRight==0 || p->zMalloc==0 );
+      sqlite3_free(p->zMalloc);
+      sqlite3_free(p);
+      p = pRight;
+    }
+  }
+}
+
+/*
+** Add a term to the segment being constructed by the SegmentWriter object
+** *ppWriter. When adding the first term to a segment, *ppWriter should
+** be passed NULL. This function will allocate a new SegmentWriter object
+** and return it via the input/output variable *ppWriter in this case.
+**
+** If successful, SQLITE_OK is returned. Otherwise, an SQLite error code.
+*/
+static int fts3SegWriterAdd(
+  Fts3Table *p,                   /* Virtual table handle */
+  SegmentWriter **ppWriter,       /* IN/OUT: SegmentWriter handle */ 
+  int isCopyTerm,                 /* True if buffer zTerm must be copied */
+  const char *zTerm,              /* Pointer to buffer containing term */
+  int nTerm,                      /* Size of term in bytes */
+  const char *aDoclist,           /* Pointer to buffer containing doclist */
+  int nDoclist                    /* Size of doclist in bytes */
+){
+  int nPrefix;                    /* Size of term prefix in bytes */
+  int nSuffix;                    /* Size of term suffix in bytes */
+  int nReq;                       /* Number of bytes required on leaf page */
+  int nData;
+  SegmentWriter *pWriter = *ppWriter;
+
+  if( !pWriter ){
+    int rc;
+    sqlite3_stmt *pStmt;
+
+    /* Allocate the SegmentWriter structure */
+    pWriter = (SegmentWriter *)sqlite3_malloc(sizeof(SegmentWriter));
+    if( !pWriter ) return SQLITE_NOMEM;
+    memset(pWriter, 0, sizeof(SegmentWriter));
+    *ppWriter = pWriter;
+
+    /* Allocate a buffer in which to accumulate data */
+    pWriter->aData = (char *)sqlite3_malloc(p->nNodeSize);
+    if( !pWriter->aData ) return SQLITE_NOMEM;
+    pWriter->nSize = p->nNodeSize;
+
+    /* Find the next free blockid in the %_segments table */
+    rc = fts3SqlStmt(p, SQL_NEXT_SEGMENTS_ID, &pStmt, 0);
+    if( rc!=SQLITE_OK ) return rc;
+    if( SQLITE_ROW==sqlite3_step(pStmt) ){
+      pWriter->iFree = sqlite3_column_int64(pStmt, 0);
+      pWriter->iFirst = pWriter->iFree;
+    }
+    rc = sqlite3_reset(pStmt);
+    if( rc!=SQLITE_OK ) return rc;
+  }
+  nData = pWriter->nData;
+
+  nPrefix = fts3PrefixCompress(pWriter->zTerm, pWriter->nTerm, zTerm, nTerm);
+  nSuffix = nTerm-nPrefix;
+
+  /* Figure out how many bytes are required by this new entry */
+  nReq = sqlite3Fts3VarintLen(nPrefix) +    /* varint containing prefix size */
+    sqlite3Fts3VarintLen(nSuffix) +         /* varint containing suffix size */
+    nSuffix +                               /* Term suffix */
+    sqlite3Fts3VarintLen(nDoclist) +        /* Size of doclist */
+    nDoclist;                               /* Doclist data */
+
+  if( nData>0 && nData+nReq>p->nNodeSize ){
+    int rc;
+
+    /* The current leaf node is full. Write it out to the database. */
+    rc = fts3WriteSegment(p, pWriter->iFree++, pWriter->aData, nData);
+    if( rc!=SQLITE_OK ) return rc;
+    p->nLeafAdd++;
+
+    /* Add the current term to the interior node tree. The term added to
+    ** the interior tree must:
+    **
+    **   a) be greater than the largest term on the leaf node just written
+    **      to the database (still available in pWriter->zTerm), and
+    **
+    **   b) be less than or equal to the term about to be added to the new
+    **      leaf node (zTerm/nTerm).
+    **
+    ** In other words, it must be the prefix of zTerm 1 byte longer than
+    ** the common prefix (if any) of zTerm and pWriter->zTerm.
+    */
+    assert( nPrefix<nTerm );
+    rc = fts3NodeAddTerm(p, &pWriter->pTree, isCopyTerm, zTerm, nPrefix+1);
+    if( rc!=SQLITE_OK ) return rc;
+
+    nData = 0;
+    pWriter->nTerm = 0;
+
+    nPrefix = 0;
+    nSuffix = nTerm;
+    nReq = 1 +                              /* varint containing prefix size */
+      sqlite3Fts3VarintLen(nTerm) +         /* varint containing suffix size */
+      nTerm +                               /* Term suffix */
+      sqlite3Fts3VarintLen(nDoclist) +      /* Size of doclist */
+      nDoclist;                             /* Doclist data */
+  }
+
+  /* Increase the total number of bytes written to account for the new entry. */
+  pWriter->nLeafData += nReq;
+
+  /* If the buffer currently allocated is too small for this entry, realloc
+  ** the buffer to make it large enough.
+  */
+  if( nReq>pWriter->nSize ){
+    char *aNew = sqlite3_realloc(pWriter->aData, nReq);
+    if( !aNew ) return SQLITE_NOMEM;
+    pWriter->aData = aNew;
+    pWriter->nSize = nReq;
+  }
+  assert( nData+nReq<=pWriter->nSize );
+
+  /* Append the prefix-compressed term and doclist to the buffer. */
+  nData += sqlite3Fts3PutVarint(&pWriter->aData[nData], nPrefix);
+  nData += sqlite3Fts3PutVarint(&pWriter->aData[nData], nSuffix);
+  memcpy(&pWriter->aData[nData], &zTerm[nPrefix], nSuffix);
+  nData += nSuffix;
+  nData += sqlite3Fts3PutVarint(&pWriter->aData[nData], nDoclist);
+  memcpy(&pWriter->aData[nData], aDoclist, nDoclist);
+  pWriter->nData = nData + nDoclist;
+
+  /* Save the current term so that it can be used to prefix-compress the next.
+  ** If the isCopyTerm parameter is true, then the buffer pointed to by
+  ** zTerm is transient, so take a copy of the term data. Otherwise, just
+  ** store a copy of the pointer.
+  */
+  if( isCopyTerm ){
+    if( nTerm>pWriter->nMalloc ){
+      char *zNew = sqlite3_realloc(pWriter->zMalloc, nTerm*2);
+      if( !zNew ){
+        return SQLITE_NOMEM;
+      }
+      pWriter->nMalloc = nTerm*2;
+      pWriter->zMalloc = zNew;
+      pWriter->zTerm = zNew;
+    }
+    assert( pWriter->zTerm==pWriter->zMalloc );
+    memcpy(pWriter->zTerm, zTerm, nTerm);
+  }else{
+    pWriter->zTerm = (char *)zTerm;
+  }
+  pWriter->nTerm = nTerm;
+
+  return SQLITE_OK;
+}
+
+/*
+** Flush all data associated with the SegmentWriter object pWriter to the
+** database. This function must be called after all terms have been added
+** to the segment using fts3SegWriterAdd(). If successful, SQLITE_OK is
+** returned. Otherwise, an SQLite error code.
+*/
+static int fts3SegWriterFlush(
+  Fts3Table *p,                   /* Virtual table handle */
+  SegmentWriter *pWriter,         /* SegmentWriter to flush to the db */
+  sqlite3_int64 iLevel,           /* Value for 'level' column of %_segdir */
+  int iIdx                        /* Value for 'idx' column of %_segdir */
+){
+  int rc;                         /* Return code */
+  if( pWriter->pTree ){
+    sqlite3_int64 iLast = 0;      /* Largest block id written to database */
+    sqlite3_int64 iLastLeaf;      /* Largest leaf block id written to db */
+    char *zRoot = NULL;           /* Pointer to buffer containing root node */
+    int nRoot = 0;                /* Size of buffer zRoot */
+
+    iLastLeaf = pWriter->iFree;
+    rc = fts3WriteSegment(p, pWriter->iFree++, pWriter->aData, pWriter->nData);
+    if( rc==SQLITE_OK ){
+      rc = fts3NodeWrite(p, pWriter->pTree, 1,
+          pWriter->iFirst, pWriter->iFree, &iLast, &zRoot, &nRoot);
+    }
+    if( rc==SQLITE_OK ){
+      rc = fts3WriteSegdir(p, iLevel, iIdx, 
+          pWriter->iFirst, iLastLeaf, iLast, pWriter->nLeafData, zRoot, nRoot);
+    }
+  }else{
+    /* The entire tree fits on the root node. Write it to the segdir table. */
+    rc = fts3WriteSegdir(p, iLevel, iIdx, 
+        0, 0, 0, pWriter->nLeafData, pWriter->aData, pWriter->nData);
+  }
+  p->nLeafAdd++;
+  return rc;
+}
+
+/*
+** Release all memory held by the SegmentWriter object passed as the 
+** first argument.
+*/
+static void fts3SegWriterFree(SegmentWriter *pWriter){
+  if( pWriter ){
+    sqlite3_free(pWriter->aData);
+    sqlite3_free(pWriter->zMalloc);
+    fts3NodeFree(pWriter->pTree);
+    sqlite3_free(pWriter);
+  }
+}
+
+/*
+** The first value in the apVal[] array is assumed to contain an integer.
+** This function tests if there exist any documents with docid values that
+** are different from that integer. i.e. if deleting the document with docid
+** pRowid would mean the FTS3 table were empty.
+**
+** If successful, *pisEmpty is set to true if the table is empty except for
+** document pRowid, or false otherwise, and SQLITE_OK is returned. If an
+** error occurs, an SQLite error code is returned.
+*/
+static int fts3IsEmpty(Fts3Table *p, sqlite3_value *pRowid, int *pisEmpty){
+  sqlite3_stmt *pStmt;
+  int rc;
+  if( p->zContentTbl ){
+    /* If using the content=xxx option, assume the table is never empty */
+    *pisEmpty = 0;
+    rc = SQLITE_OK;
+  }else{
+    rc = fts3SqlStmt(p, SQL_IS_EMPTY, &pStmt, &pRowid);
+    if( rc==SQLITE_OK ){
+      if( SQLITE_ROW==sqlite3_step(pStmt) ){
+        *pisEmpty = sqlite3_column_int(pStmt, 0);
+      }
+      rc = sqlite3_reset(pStmt);
+    }
+  }
+  return rc;
+}
+
+/*
+** Set *pnMax to the largest segment level in the database for the index
+** iIndex.
+**
+** Segment levels are stored in the 'level' column of the %_segdir table.
+**
+** Return SQLITE_OK if successful, or an SQLite error code if not.
+*/
+static int fts3SegmentMaxLevel(
+  Fts3Table *p, 
+  int iLangid,
+  int iIndex, 
+  sqlite3_int64 *pnMax
+){
+  sqlite3_stmt *pStmt;
+  int rc;
+  assert( iIndex>=0 && iIndex<p->nIndex );
+
+  /* Set pStmt to the compiled version of:
+  **
+  **   SELECT max(level) FROM %Q.'%q_segdir' WHERE level BETWEEN ? AND ?
+  **
+  ** (1024 is actually the value of macro FTS3_SEGDIR_PREFIXLEVEL_STR).
+  */
+  rc = fts3SqlStmt(p, SQL_SELECT_SEGDIR_MAX_LEVEL, &pStmt, 0);
+  if( rc!=SQLITE_OK ) return rc;
+  sqlite3_bind_int64(pStmt, 1, getAbsoluteLevel(p, iLangid, iIndex, 0));
+  sqlite3_bind_int64(pStmt, 2, 
+      getAbsoluteLevel(p, iLangid, iIndex, FTS3_SEGDIR_MAXLEVEL-1)
+  );
+  if( SQLITE_ROW==sqlite3_step(pStmt) ){
+    *pnMax = sqlite3_column_int64(pStmt, 0);
+  }
+  return sqlite3_reset(pStmt);
+}
+
+/*
+** iAbsLevel is an absolute level that may be assumed to exist within
+** the database. This function checks if it is the largest level number
+** within its index. Assuming no error occurs, *pbMax is set to 1 if
+** iAbsLevel is indeed the largest level, or 0 otherwise, and SQLITE_OK
+** is returned. If an error occurs, an error code is returned and the
+** final value of *pbMax is undefined.
+*/
+static int fts3SegmentIsMaxLevel(Fts3Table *p, i64 iAbsLevel, int *pbMax){
+
+  /* Set pStmt to the compiled version of:
+  **
+  **   SELECT max(level) FROM %Q.'%q_segdir' WHERE level BETWEEN ? AND ?
+  **
+  ** (1024 is actually the value of macro FTS3_SEGDIR_PREFIXLEVEL_STR).
+  */
+  sqlite3_stmt *pStmt;
+  int rc = fts3SqlStmt(p, SQL_SELECT_SEGDIR_MAX_LEVEL, &pStmt, 0);
+  if( rc!=SQLITE_OK ) return rc;
+  sqlite3_bind_int64(pStmt, 1, iAbsLevel+1);
+  sqlite3_bind_int64(pStmt, 2, 
+      ((iAbsLevel/FTS3_SEGDIR_MAXLEVEL)+1) * FTS3_SEGDIR_MAXLEVEL
+  );
+
+  *pbMax = 0;
+  if( SQLITE_ROW==sqlite3_step(pStmt) ){
+    *pbMax = sqlite3_column_type(pStmt, 0)==SQLITE_NULL;
+  }
+  return sqlite3_reset(pStmt);
+}
+
+/*
+** Delete all entries in the %_segments table associated with the segment
+** opened with seg-reader pSeg. This function does not affect the contents
+** of the %_segdir table.
+*/
+static int fts3DeleteSegment(
+  Fts3Table *p,                   /* FTS table handle */
+  Fts3SegReader *pSeg             /* Segment to delete */
+){
+  int rc = SQLITE_OK;             /* Return code */
+  if( pSeg->iStartBlock ){
+    sqlite3_stmt *pDelete;        /* SQL statement to delete rows */
+    rc = fts3SqlStmt(p, SQL_DELETE_SEGMENTS_RANGE, &pDelete, 0);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_int64(pDelete, 1, pSeg->iStartBlock);
+      sqlite3_bind_int64(pDelete, 2, pSeg->iEndBlock);
+      sqlite3_step(pDelete);
+      rc = sqlite3_reset(pDelete);
+    }
+  }
+  return rc;
+}
+
+/*
+** This function is used after merging multiple segments into a single large
+** segment to delete the old, now redundant, segment b-trees. Specifically,
+** it:
+** 
+**   1) Deletes all %_segments entries for the segments associated with 
+**      each of the SegReader objects in the array passed as the third 
+**      argument, and
+**
+**   2) deletes all %_segdir entries with level iLevel, or all %_segdir
+**      entries regardless of level if (iLevel<0).
+**
+** SQLITE_OK is returned if successful, otherwise an SQLite error code.
+*/
+static int fts3DeleteSegdir(
+  Fts3Table *p,                   /* Virtual table handle */
+  int iLangid,                    /* Language id */
+  int iIndex,                     /* Index for p->aIndex */
+  int iLevel,                     /* Level of %_segdir entries to delete */
+  Fts3SegReader **apSegment,      /* Array of SegReader objects */
+  int nReader                     /* Size of array apSegment */
+){
+  int rc = SQLITE_OK;             /* Return Code */
+  int i;                          /* Iterator variable */
+  sqlite3_stmt *pDelete = 0;      /* SQL statement to delete rows */
+
+  for(i=0; rc==SQLITE_OK && i<nReader; i++){
+    rc = fts3DeleteSegment(p, apSegment[i]);
+  }
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+
+  assert( iLevel>=0 || iLevel==FTS3_SEGCURSOR_ALL );
+  if( iLevel==FTS3_SEGCURSOR_ALL ){
+    rc = fts3SqlStmt(p, SQL_DELETE_SEGDIR_RANGE, &pDelete, 0);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_int64(pDelete, 1, getAbsoluteLevel(p, iLangid, iIndex, 0));
+      sqlite3_bind_int64(pDelete, 2, 
+          getAbsoluteLevel(p, iLangid, iIndex, FTS3_SEGDIR_MAXLEVEL-1)
+      );
+    }
+  }else{
+    rc = fts3SqlStmt(p, SQL_DELETE_SEGDIR_LEVEL, &pDelete, 0);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_int64(
+          pDelete, 1, getAbsoluteLevel(p, iLangid, iIndex, iLevel)
+      );
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    sqlite3_step(pDelete);
+    rc = sqlite3_reset(pDelete);
+  }
+
+  return rc;
+}
+
+/*
+** When this function is called, buffer *ppList (size *pnList bytes) contains 
+** a position list that may (or may not) feature multiple columns. This
+** function adjusts the pointer *ppList and the length *pnList so that they
+** identify the subset of the position list that corresponds to column iCol.
+**
+** If there are no entries in the input position list for column iCol, then
+** *pnList is set to zero before returning.
+**
+** If parameter bZero is non-zero, then any part of the input list following
+** the end of the output list is zeroed before returning.
+*/
+static void fts3ColumnFilter(
+  int iCol,                       /* Column to filter on */
+  int bZero,                      /* Zero out anything following *ppList */
+  char **ppList,                  /* IN/OUT: Pointer to position list */
+  int *pnList                     /* IN/OUT: Size of buffer *ppList in bytes */
+){
+  char *pList = *ppList;
+  int nList = *pnList;
+  char *pEnd = &pList[nList];
+  int iCurrent = 0;
+  char *p = pList;
+
+  assert( iCol>=0 );
+  while( 1 ){
+    char c = 0;
+    while( p<pEnd && (c | *p)&0xFE ) c = *p++ & 0x80;
+  
+    if( iCol==iCurrent ){
+      nList = (int)(p - pList);
+      break;
+    }
+
+    nList -= (int)(p - pList);
+    pList = p;
+    if( nList==0 ){
+      break;
+    }
+    p = &pList[1];
+    p += fts3GetVarint32(p, &iCurrent);
+  }
+
+  if( bZero && &pList[nList]!=pEnd ){
+    memset(&pList[nList], 0, pEnd - &pList[nList]);
+  }
+  *ppList = pList;
+  *pnList = nList;
+}
+
+/*
+** Cache data in the Fts3MultiSegReader.aBuffer[] buffer (overwriting any
+** existing data). Grow the buffer if required.
+**
+** If successful, return SQLITE_OK. Otherwise, if an OOM error is encountered
+** trying to resize the buffer, return SQLITE_NOMEM.
+*/
+static int fts3MsrBufferData(
+  Fts3MultiSegReader *pMsr,       /* Multi-segment-reader handle */
+  char *pList,
+  int nList
+){
+  if( nList>pMsr->nBuffer ){
+    char *pNew;
+    pMsr->nBuffer = nList*2;
+    pNew = (char *)sqlite3_realloc(pMsr->aBuffer, pMsr->nBuffer);
+    if( !pNew ) return SQLITE_NOMEM;
+    pMsr->aBuffer = pNew;
+  }
+
+  memcpy(pMsr->aBuffer, pList, nList);
+  return SQLITE_OK;
+}
+
+SQLITE_PRIVATE int sqlite3Fts3MsrIncrNext(
+  Fts3Table *p,                   /* Virtual table handle */
+  Fts3MultiSegReader *pMsr,       /* Multi-segment-reader handle */
+  sqlite3_int64 *piDocid,         /* OUT: Docid value */
+  char **paPoslist,               /* OUT: Pointer to position list */
+  int *pnPoslist                  /* OUT: Size of position list in bytes */
+){
+  int nMerge = pMsr->nAdvance;
+  Fts3SegReader **apSegment = pMsr->apSegment;
+  int (*xCmp)(Fts3SegReader *, Fts3SegReader *) = (
+    p->bDescIdx ? fts3SegReaderDoclistCmpRev : fts3SegReaderDoclistCmp
+  );
+
+  if( nMerge==0 ){
+    *paPoslist = 0;
+    return SQLITE_OK;
+  }
+
+  while( 1 ){
+    Fts3SegReader *pSeg;
+    pSeg = pMsr->apSegment[0];
+
+    if( pSeg->pOffsetList==0 ){
+      *paPoslist = 0;
+      break;
+    }else{
+      int rc;
+      char *pList;
+      int nList;
+      int j;
+      sqlite3_int64 iDocid = apSegment[0]->iDocid;
+
+      rc = fts3SegReaderNextDocid(p, apSegment[0], &pList, &nList);
+      j = 1;
+      while( rc==SQLITE_OK 
+        && j<nMerge
+        && apSegment[j]->pOffsetList
+        && apSegment[j]->iDocid==iDocid
+      ){
+        rc = fts3SegReaderNextDocid(p, apSegment[j], 0, 0);
+        j++;
+      }
+      if( rc!=SQLITE_OK ) return rc;
+      fts3SegReaderSort(pMsr->apSegment, nMerge, j, xCmp);
+
+      if( nList>0 && fts3SegReaderIsPending(apSegment[0]) ){
+        rc = fts3MsrBufferData(pMsr, pList, nList+1);
+        if( rc!=SQLITE_OK ) return rc;
+        assert( (pMsr->aBuffer[nList] & 0xFE)==0x00 );
+        pList = pMsr->aBuffer;
+      }
+
+      if( pMsr->iColFilter>=0 ){
+        fts3ColumnFilter(pMsr->iColFilter, 1, &pList, &nList);
+      }
+
+      if( nList>0 ){
+        *paPoslist = pList;
+        *piDocid = iDocid;
+        *pnPoslist = nList;
+        break;
+      }
+    }
+  }
+
+  return SQLITE_OK;
+}
+
+static int fts3SegReaderStart(
+  Fts3Table *p,                   /* Virtual table handle */
+  Fts3MultiSegReader *pCsr,       /* Cursor object */
+  const char *zTerm,              /* Term searched for (or NULL) */
+  int nTerm                       /* Length of zTerm in bytes */
+){
+  int i;
+  int nSeg = pCsr->nSegment;
+
+  /* If the Fts3SegFilter defines a specific term (or term prefix) to search 
+  ** for, then advance each segment iterator until it points to a term of
+  ** equal or greater value than the specified term. This prevents many
+  ** unnecessary merge/sort operations for the case where single segment
+  ** b-tree leaf nodes contain more than one term.
+  */
+  for(i=0; pCsr->bRestart==0 && i<pCsr->nSegment; i++){
+    int res = 0;
+    Fts3SegReader *pSeg = pCsr->apSegment[i];
+    do {
+      int rc = fts3SegReaderNext(p, pSeg, 0);
+      if( rc!=SQLITE_OK ) return rc;
+    }while( zTerm && (res = fts3SegReaderTermCmp(pSeg, zTerm, nTerm))<0 );
+
+    if( pSeg->bLookup && res!=0 ){
+      fts3SegReaderSetEof(pSeg);
+    }
+  }
+  fts3SegReaderSort(pCsr->apSegment, nSeg, nSeg, fts3SegReaderCmp);
+
+  return SQLITE_OK;
+}
+
+SQLITE_PRIVATE int sqlite3Fts3SegReaderStart(
+  Fts3Table *p,                   /* Virtual table handle */
+  Fts3MultiSegReader *pCsr,       /* Cursor object */
+  Fts3SegFilter *pFilter          /* Restrictions on range of iteration */
+){
+  pCsr->pFilter = pFilter;
+  return fts3SegReaderStart(p, pCsr, pFilter->zTerm, pFilter->nTerm);
+}
+
+SQLITE_PRIVATE int sqlite3Fts3MsrIncrStart(
+  Fts3Table *p,                   /* Virtual table handle */
+  Fts3MultiSegReader *pCsr,       /* Cursor object */
+  int iCol,                       /* Column to match on. */
+  const char *zTerm,              /* Term to iterate through a doclist for */
+  int nTerm                       /* Number of bytes in zTerm */
+){
+  int i;
+  int rc;
+  int nSegment = pCsr->nSegment;
+  int (*xCmp)(Fts3SegReader *, Fts3SegReader *) = (
+    p->bDescIdx ? fts3SegReaderDoclistCmpRev : fts3SegReaderDoclistCmp
+  );
+
+  assert( pCsr->pFilter==0 );
+  assert( zTerm && nTerm>0 );
+
+  /* Advance each segment iterator until it points to the term zTerm/nTerm. */
+  rc = fts3SegReaderStart(p, pCsr, zTerm, nTerm);
+  if( rc!=SQLITE_OK ) return rc;
+
+  /* Determine how many of the segments actually point to zTerm/nTerm. */
+  for(i=0; i<nSegment; i++){
+    Fts3SegReader *pSeg = pCsr->apSegment[i];
+    if( !pSeg->aNode || fts3SegReaderTermCmp(pSeg, zTerm, nTerm) ){
+      break;
+    }
+  }
+  pCsr->nAdvance = i;
+
+  /* Advance each of the segments to point to the first docid. */
+  for(i=0; i<pCsr->nAdvance; i++){
+    rc = fts3SegReaderFirstDocid(p, pCsr->apSegment[i]);
+    if( rc!=SQLITE_OK ) return rc;
+  }
+  fts3SegReaderSort(pCsr->apSegment, i, i, xCmp);
+
+  assert( iCol<0 || iCol<p->nColumn );
+  pCsr->iColFilter = iCol;
+
+  return SQLITE_OK;
+}
+
+/*
+** This function is called on a MultiSegReader that has been started using
+** sqlite3Fts3MsrIncrStart(). One or more calls to MsrIncrNext() may also
+** have been made. Calling this function puts the MultiSegReader in such
+** a state that if the next two calls are:
+**
+**   sqlite3Fts3SegReaderStart()
+**   sqlite3Fts3SegReaderStep()
+**
+** then the entire doclist for the term is available in 
+** MultiSegReader.aDoclist/nDoclist.
+*/
+SQLITE_PRIVATE int sqlite3Fts3MsrIncrRestart(Fts3MultiSegReader *pCsr){
+  int i;                          /* Used to iterate through segment-readers */
+
+  assert( pCsr->zTerm==0 );
+  assert( pCsr->nTerm==0 );
+  assert( pCsr->aDoclist==0 );
+  assert( pCsr->nDoclist==0 );
+
+  pCsr->nAdvance = 0;
+  pCsr->bRestart = 1;
+  for(i=0; i<pCsr->nSegment; i++){
+    pCsr->apSegment[i]->pOffsetList = 0;
+    pCsr->apSegment[i]->nOffsetList = 0;
+    pCsr->apSegment[i]->iDocid = 0;
+  }
+
+  return SQLITE_OK;
+}
+
+
+SQLITE_PRIVATE int sqlite3Fts3SegReaderStep(
+  Fts3Table *p,                   /* Virtual table handle */
+  Fts3MultiSegReader *pCsr        /* Cursor object */
+){
+  int rc = SQLITE_OK;
+
+  int isIgnoreEmpty =  (pCsr->pFilter->flags & FTS3_SEGMENT_IGNORE_EMPTY);
+  int isRequirePos =   (pCsr->pFilter->flags & FTS3_SEGMENT_REQUIRE_POS);
+  int isColFilter =    (pCsr->pFilter->flags & FTS3_SEGMENT_COLUMN_FILTER);
+  int isPrefix =       (pCsr->pFilter->flags & FTS3_SEGMENT_PREFIX);
+  int isScan =         (pCsr->pFilter->flags & FTS3_SEGMENT_SCAN);
+  int isFirst =        (pCsr->pFilter->flags & FTS3_SEGMENT_FIRST);
+
+  Fts3SegReader **apSegment = pCsr->apSegment;
+  int nSegment = pCsr->nSegment;
+  Fts3SegFilter *pFilter = pCsr->pFilter;
+  int (*xCmp)(Fts3SegReader *, Fts3SegReader *) = (
+    p->bDescIdx ? fts3SegReaderDoclistCmpRev : fts3SegReaderDoclistCmp
+  );
+
+  if( pCsr->nSegment==0 ) return SQLITE_OK;
+
+  do {
+    int nMerge;
+    int i;
+  
+    /* Advance the first pCsr->nAdvance entries in the apSegment[] array
+    ** forward. Then sort the list in order of current term again.  
+    */
+    for(i=0; i<pCsr->nAdvance; i++){
+      Fts3SegReader *pSeg = apSegment[i];
+      if( pSeg->bLookup ){
+        fts3SegReaderSetEof(pSeg);
+      }else{
+        rc = fts3SegReaderNext(p, pSeg, 0);
+      }
+      if( rc!=SQLITE_OK ) return rc;
+    }
+    fts3SegReaderSort(apSegment, nSegment, pCsr->nAdvance, fts3SegReaderCmp);
+    pCsr->nAdvance = 0;
+
+    /* If all the seg-readers are at EOF, we're finished. return SQLITE_OK. */
+    assert( rc==SQLITE_OK );
+    if( apSegment[0]->aNode==0 ) break;
+
+    pCsr->nTerm = apSegment[0]->nTerm;
+    pCsr->zTerm = apSegment[0]->zTerm;
+
+    /* If this is a prefix-search, and if the term that apSegment[0] points
+    ** to does not share a suffix with pFilter->zTerm/nTerm, then all 
+    ** required callbacks have been made. In this case exit early.
+    **
+    ** Similarly, if this is a search for an exact match, and the first term
+    ** of segment apSegment[0] is not a match, exit early.
+    */
+    if( pFilter->zTerm && !isScan ){
+      if( pCsr->nTerm<pFilter->nTerm 
+       || (!isPrefix && pCsr->nTerm>pFilter->nTerm)
+       || memcmp(pCsr->zTerm, pFilter->zTerm, pFilter->nTerm) 
+      ){
+        break;
+      }
+    }
+
+    nMerge = 1;
+    while( nMerge<nSegment 
+        && apSegment[nMerge]->aNode
+        && apSegment[nMerge]->nTerm==pCsr->nTerm 
+        && 0==memcmp(pCsr->zTerm, apSegment[nMerge]->zTerm, pCsr->nTerm)
+    ){
+      nMerge++;
+    }
+
+    assert( isIgnoreEmpty || (isRequirePos && !isColFilter) );
+    if( nMerge==1 
+     && !isIgnoreEmpty 
+     && !isFirst 
+     && (p->bDescIdx==0 || fts3SegReaderIsPending(apSegment[0])==0)
+    ){
+      pCsr->nDoclist = apSegment[0]->nDoclist;
+      if( fts3SegReaderIsPending(apSegment[0]) ){
+        rc = fts3MsrBufferData(pCsr, apSegment[0]->aDoclist, pCsr->nDoclist);
+        pCsr->aDoclist = pCsr->aBuffer;
+      }else{
+        pCsr->aDoclist = apSegment[0]->aDoclist;
+      }
+      if( rc==SQLITE_OK ) rc = SQLITE_ROW;
+    }else{
+      int nDoclist = 0;           /* Size of doclist */
+      sqlite3_int64 iPrev = 0;    /* Previous docid stored in doclist */
+
+      /* The current term of the first nMerge entries in the array
+      ** of Fts3SegReader objects is the same. The doclists must be merged
+      ** and a single term returned with the merged doclist.
+      */
+      for(i=0; i<nMerge; i++){
+        fts3SegReaderFirstDocid(p, apSegment[i]);
+      }
+      fts3SegReaderSort(apSegment, nMerge, nMerge, xCmp);
+      while( apSegment[0]->pOffsetList ){
+        int j;                    /* Number of segments that share a docid */
+        char *pList = 0;
+        int nList = 0;
+        int nByte;
+        sqlite3_int64 iDocid = apSegment[0]->iDocid;
+        fts3SegReaderNextDocid(p, apSegment[0], &pList, &nList);
+        j = 1;
+        while( j<nMerge
+            && apSegment[j]->pOffsetList
+            && apSegment[j]->iDocid==iDocid
+        ){
+          fts3SegReaderNextDocid(p, apSegment[j], 0, 0);
+          j++;
+        }
+
+        if( isColFilter ){
+          fts3ColumnFilter(pFilter->iCol, 0, &pList, &nList);
+        }
+
+        if( !isIgnoreEmpty || nList>0 ){
+
+          /* Calculate the 'docid' delta value to write into the merged 
+          ** doclist. */
+          sqlite3_int64 iDelta;
+          if( p->bDescIdx && nDoclist>0 ){
+            iDelta = iPrev - iDocid;
+          }else{
+            iDelta = iDocid - iPrev;
+          }
+          assert( iDelta>0 || (nDoclist==0 && iDelta==iDocid) );
+          assert( nDoclist>0 || iDelta==iDocid );
+
+          nByte = sqlite3Fts3VarintLen(iDelta) + (isRequirePos?nList+1:0);
+          if( nDoclist+nByte>pCsr->nBuffer ){
+            char *aNew;
+            pCsr->nBuffer = (nDoclist+nByte)*2;
+            aNew = sqlite3_realloc(pCsr->aBuffer, pCsr->nBuffer);
+            if( !aNew ){
+              return SQLITE_NOMEM;
+            }
+            pCsr->aBuffer = aNew;
+          }
+
+          if( isFirst ){
+            char *a = &pCsr->aBuffer[nDoclist];
+            int nWrite;
+           
+            nWrite = sqlite3Fts3FirstFilter(iDelta, pList, nList, a);
+            if( nWrite ){
+              iPrev = iDocid;
+              nDoclist += nWrite;
+            }
+          }else{
+            nDoclist += sqlite3Fts3PutVarint(&pCsr->aBuffer[nDoclist], iDelta);
+            iPrev = iDocid;
+            if( isRequirePos ){
+              memcpy(&pCsr->aBuffer[nDoclist], pList, nList);
+              nDoclist += nList;
+              pCsr->aBuffer[nDoclist++] = '\0';
+            }
+          }
+        }
+
+        fts3SegReaderSort(apSegment, nMerge, j, xCmp);
+      }
+      if( nDoclist>0 ){
+        pCsr->aDoclist = pCsr->aBuffer;
+        pCsr->nDoclist = nDoclist;
+        rc = SQLITE_ROW;
+      }
+    }
+    pCsr->nAdvance = nMerge;
+  }while( rc==SQLITE_OK );
+
+  return rc;
+}
+
+
+SQLITE_PRIVATE void sqlite3Fts3SegReaderFinish(
+  Fts3MultiSegReader *pCsr       /* Cursor object */
+){
+  if( pCsr ){
+    int i;
+    for(i=0; i<pCsr->nSegment; i++){
+      sqlite3Fts3SegReaderFree(pCsr->apSegment[i]);
+    }
+    sqlite3_free(pCsr->apSegment);
+    sqlite3_free(pCsr->aBuffer);
+
+    pCsr->nSegment = 0;
+    pCsr->apSegment = 0;
+    pCsr->aBuffer = 0;
+  }
+}
+
+/*
+** Decode the "end_block" field, selected by column iCol of the SELECT 
+** statement passed as the first argument. 
+**
+** The "end_block" field may contain either an integer, or a text field
+** containing the text representation of two non-negative integers separated 
+** by one or more space (0x20) characters. In the first case, set *piEndBlock 
+** to the integer value and *pnByte to zero before returning. In the second, 
+** set *piEndBlock to the first value and *pnByte to the second.
+*/
+static void fts3ReadEndBlockField(
+  sqlite3_stmt *pStmt, 
+  int iCol, 
+  i64 *piEndBlock,
+  i64 *pnByte
+){
+  const unsigned char *zText = sqlite3_column_text(pStmt, iCol);
+  if( zText ){
+    int i;
+    int iMul = 1;
+    i64 iVal = 0;
+    for(i=0; zText[i]>='0' && zText[i]<='9'; i++){
+      iVal = iVal*10 + (zText[i] - '0');
+    }
+    *piEndBlock = iVal;
+    while( zText[i]==' ' ) i++;
+    iVal = 0;
+    if( zText[i]=='-' ){
+      i++;
+      iMul = -1;
+    }
+    for(/* no-op */; zText[i]>='0' && zText[i]<='9'; i++){
+      iVal = iVal*10 + (zText[i] - '0');
+    }
+    *pnByte = (iVal * (i64)iMul);
+  }
+}
+
+
+/*
+** A segment of size nByte bytes has just been written to absolute level
+** iAbsLevel. Promote any segments that should be promoted as a result.
+*/
+static int fts3PromoteSegments(
+  Fts3Table *p,                   /* FTS table handle */
+  sqlite3_int64 iAbsLevel,        /* Absolute level just updated */
+  sqlite3_int64 nByte             /* Size of new segment at iAbsLevel */
+){
+  int rc = SQLITE_OK;
+  sqlite3_stmt *pRange;
+
+  rc = fts3SqlStmt(p, SQL_SELECT_LEVEL_RANGE2, &pRange, 0);
+
+  if( rc==SQLITE_OK ){
+    int bOk = 0;
+    i64 iLast = (iAbsLevel/FTS3_SEGDIR_MAXLEVEL + 1) * FTS3_SEGDIR_MAXLEVEL - 1;
+    i64 nLimit = (nByte*3)/2;
+
+    /* Loop through all entries in the %_segdir table corresponding to 
+    ** segments in this index on levels greater than iAbsLevel. If there is
+    ** at least one such segment, and it is possible to determine that all 
+    ** such segments are smaller than nLimit bytes in size, they will be 
+    ** promoted to level iAbsLevel.  */
+    sqlite3_bind_int64(pRange, 1, iAbsLevel+1);
+    sqlite3_bind_int64(pRange, 2, iLast);
+    while( SQLITE_ROW==sqlite3_step(pRange) ){
+      i64 nSize = 0, dummy;
+      fts3ReadEndBlockField(pRange, 2, &dummy, &nSize);
+      if( nSize<=0 || nSize>nLimit ){
+        /* If nSize==0, then the %_segdir.end_block field does not not 
+        ** contain a size value. This happens if it was written by an
+        ** old version of FTS. In this case it is not possible to determine
+        ** the size of the segment, and so segment promotion does not
+        ** take place.  */
+        bOk = 0;
+        break;
+      }
+      bOk = 1;
+    }
+    rc = sqlite3_reset(pRange);
+
+    if( bOk ){
+      int iIdx = 0;
+      sqlite3_stmt *pUpdate1 = 0;
+      sqlite3_stmt *pUpdate2 = 0;
+
+      if( rc==SQLITE_OK ){
+        rc = fts3SqlStmt(p, SQL_UPDATE_LEVEL_IDX, &pUpdate1, 0);
+      }
+      if( rc==SQLITE_OK ){
+        rc = fts3SqlStmt(p, SQL_UPDATE_LEVEL, &pUpdate2, 0);
+      }
+
+      if( rc==SQLITE_OK ){
+
+        /* Loop through all %_segdir entries for segments in this index with
+        ** levels equal to or greater than iAbsLevel. As each entry is visited,
+        ** updated it to set (level = -1) and (idx = N), where N is 0 for the
+        ** oldest segment in the range, 1 for the next oldest, and so on.
+        **
+        ** In other words, move all segments being promoted to level -1,
+        ** setting the "idx" fields as appropriate to keep them in the same
+        ** order. The contents of level -1 (which is never used, except
+        ** transiently here), will be moved back to level iAbsLevel below.  */
+        sqlite3_bind_int64(pRange, 1, iAbsLevel);
+        while( SQLITE_ROW==sqlite3_step(pRange) ){
+          sqlite3_bind_int(pUpdate1, 1, iIdx++);
+          sqlite3_bind_int(pUpdate1, 2, sqlite3_column_int(pRange, 0));
+          sqlite3_bind_int(pUpdate1, 3, sqlite3_column_int(pRange, 1));
+          sqlite3_step(pUpdate1);
+          rc = sqlite3_reset(pUpdate1);
+          if( rc!=SQLITE_OK ){
+            sqlite3_reset(pRange);
+            break;
+          }
+        }
+      }
+      if( rc==SQLITE_OK ){
+        rc = sqlite3_reset(pRange);
+      }
+
+      /* Move level -1 to level iAbsLevel */
+      if( rc==SQLITE_OK ){
+        sqlite3_bind_int64(pUpdate2, 1, iAbsLevel);
+        sqlite3_step(pUpdate2);
+        rc = sqlite3_reset(pUpdate2);
+      }
+    }
+  }
+
+
+  return rc;
+}
+
+/*
+** Merge all level iLevel segments in the database into a single 
+** iLevel+1 segment. Or, if iLevel<0, merge all segments into a
+** single segment with a level equal to the numerically largest level 
+** currently present in the database.
+**
+** If this function is called with iLevel<0, but there is only one
+** segment in the database, SQLITE_DONE is returned immediately. 
+** Otherwise, if successful, SQLITE_OK is returned. If an error occurs, 
+** an SQLite error code is returned.
+*/
+static int fts3SegmentMerge(
+  Fts3Table *p, 
+  int iLangid,                    /* Language id to merge */
+  int iIndex,                     /* Index in p->aIndex[] to merge */
+  int iLevel                      /* Level to merge */
+){
+  int rc;                         /* Return code */
+  int iIdx = 0;                   /* Index of new segment */
+  sqlite3_int64 iNewLevel = 0;    /* Level/index to create new segment at */
+  SegmentWriter *pWriter = 0;     /* Used to write the new, merged, segment */
+  Fts3SegFilter filter;           /* Segment term filter condition */
+  Fts3MultiSegReader csr;         /* Cursor to iterate through level(s) */
+  int bIgnoreEmpty = 0;           /* True to ignore empty segments */
+  i64 iMaxLevel = 0;              /* Max level number for this index/langid */
+
+  assert( iLevel==FTS3_SEGCURSOR_ALL
+       || iLevel==FTS3_SEGCURSOR_PENDING
+       || iLevel>=0
+  );
+  assert( iLevel<FTS3_SEGDIR_MAXLEVEL );
+  assert( iIndex>=0 && iIndex<p->nIndex );
+
+  rc = sqlite3Fts3SegReaderCursor(p, iLangid, iIndex, iLevel, 0, 0, 1, 0, &csr);
+  if( rc!=SQLITE_OK || csr.nSegment==0 ) goto finished;
+
+  if( iLevel!=FTS3_SEGCURSOR_PENDING ){
+    rc = fts3SegmentMaxLevel(p, iLangid, iIndex, &iMaxLevel);
+    if( rc!=SQLITE_OK ) goto finished;
+  }
+
+  if( iLevel==FTS3_SEGCURSOR_ALL ){
+    /* This call is to merge all segments in the database to a single
+    ** segment. The level of the new segment is equal to the numerically
+    ** greatest segment level currently present in the database for this
+    ** index. The idx of the new segment is always 0.  */
+    if( csr.nSegment==1 && 0==fts3SegReaderIsPending(csr.apSegment[0]) ){
+      rc = SQLITE_DONE;
+      goto finished;
+    }
+    iNewLevel = iMaxLevel;
+    bIgnoreEmpty = 1;
+
+  }else{
+    /* This call is to merge all segments at level iLevel. find the next
+    ** available segment index at level iLevel+1. The call to
+    ** fts3AllocateSegdirIdx() will merge the segments at level iLevel+1 to 
+    ** a single iLevel+2 segment if necessary.  */
+    assert( FTS3_SEGCURSOR_PENDING==-1 );
+    iNewLevel = getAbsoluteLevel(p, iLangid, iIndex, iLevel+1);
+    rc = fts3AllocateSegdirIdx(p, iLangid, iIndex, iLevel+1, &iIdx);
+    bIgnoreEmpty = (iLevel!=FTS3_SEGCURSOR_PENDING) && (iNewLevel>iMaxLevel);
+  }
+  if( rc!=SQLITE_OK ) goto finished;
+
+  assert( csr.nSegment>0 );
+  assert( iNewLevel>=getAbsoluteLevel(p, iLangid, iIndex, 0) );
+  assert( iNewLevel<getAbsoluteLevel(p, iLangid, iIndex,FTS3_SEGDIR_MAXLEVEL) );
+
+  memset(&filter, 0, sizeof(Fts3SegFilter));
+  filter.flags = FTS3_SEGMENT_REQUIRE_POS;
+  filter.flags |= (bIgnoreEmpty ? FTS3_SEGMENT_IGNORE_EMPTY : 0);
+
+  rc = sqlite3Fts3SegReaderStart(p, &csr, &filter);
+  while( SQLITE_OK==rc ){
+    rc = sqlite3Fts3SegReaderStep(p, &csr);
+    if( rc!=SQLITE_ROW ) break;
+    rc = fts3SegWriterAdd(p, &pWriter, 1, 
+        csr.zTerm, csr.nTerm, csr.aDoclist, csr.nDoclist);
+  }
+  if( rc!=SQLITE_OK ) goto finished;
+  assert( pWriter || bIgnoreEmpty );
+
+  if( iLevel!=FTS3_SEGCURSOR_PENDING ){
+    rc = fts3DeleteSegdir(
+        p, iLangid, iIndex, iLevel, csr.apSegment, csr.nSegment
+    );
+    if( rc!=SQLITE_OK ) goto finished;
+  }
+  if( pWriter ){
+    rc = fts3SegWriterFlush(p, pWriter, iNewLevel, iIdx);
+    if( rc==SQLITE_OK ){
+      if( iLevel==FTS3_SEGCURSOR_PENDING || iNewLevel<iMaxLevel ){
+        rc = fts3PromoteSegments(p, iNewLevel, pWriter->nLeafData);
+      }
+    }
+  }
+
+ finished:
+  fts3SegWriterFree(pWriter);
+  sqlite3Fts3SegReaderFinish(&csr);
+  return rc;
+}
+
+
+/* 
+** Flush the contents of pendingTerms to level 0 segments. 
+*/
+SQLITE_PRIVATE int sqlite3Fts3PendingTermsFlush(Fts3Table *p){
+  int rc = SQLITE_OK;
+  int i;
+        
+  for(i=0; rc==SQLITE_OK && i<p->nIndex; i++){
+    rc = fts3SegmentMerge(p, p->iPrevLangid, i, FTS3_SEGCURSOR_PENDING);
+    if( rc==SQLITE_DONE ) rc = SQLITE_OK;
+  }
+  sqlite3Fts3PendingTermsClear(p);
+
+  /* Determine the auto-incr-merge setting if unknown.  If enabled,
+  ** estimate the number of leaf blocks of content to be written
+  */
+  if( rc==SQLITE_OK && p->bHasStat
+   && p->nAutoincrmerge==0xff && p->nLeafAdd>0
+  ){
+    sqlite3_stmt *pStmt = 0;
+    rc = fts3SqlStmt(p, SQL_SELECT_STAT, &pStmt, 0);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_int(pStmt, 1, FTS_STAT_AUTOINCRMERGE);
+      rc = sqlite3_step(pStmt);
+      if( rc==SQLITE_ROW ){
+        p->nAutoincrmerge = sqlite3_column_int(pStmt, 0);
+        if( p->nAutoincrmerge==1 ) p->nAutoincrmerge = 8;
+      }else if( rc==SQLITE_DONE ){
+        p->nAutoincrmerge = 0;
+      }
+      rc = sqlite3_reset(pStmt);
+    }
+  }
+  return rc;
+}
+
+/*
+** Encode N integers as varints into a blob.
+*/
+static void fts3EncodeIntArray(
+  int N,             /* The number of integers to encode */
+  u32 *a,            /* The integer values */
+  char *zBuf,        /* Write the BLOB here */
+  int *pNBuf         /* Write number of bytes if zBuf[] used here */
+){
+  int i, j;
+  for(i=j=0; i<N; i++){
+    j += sqlite3Fts3PutVarint(&zBuf[j], (sqlite3_int64)a[i]);
+  }
+  *pNBuf = j;
+}
+
+/*
+** Decode a blob of varints into N integers
+*/
+static void fts3DecodeIntArray(
+  int N,             /* The number of integers to decode */
+  u32 *a,            /* Write the integer values */
+  const char *zBuf,  /* The BLOB containing the varints */
+  int nBuf           /* size of the BLOB */
+){
+  int i, j;
+  UNUSED_PARAMETER(nBuf);
+  for(i=j=0; i<N; i++){
+    sqlite3_int64 x;
+    j += sqlite3Fts3GetVarint(&zBuf[j], &x);
+    assert(j<=nBuf);
+    a[i] = (u32)(x & 0xffffffff);
+  }
+}
+
+/*
+** Insert the sizes (in tokens) for each column of the document
+** with docid equal to p->iPrevDocid.  The sizes are encoded as
+** a blob of varints.
+*/
+static void fts3InsertDocsize(
+  int *pRC,                       /* Result code */
+  Fts3Table *p,                   /* Table into which to insert */
+  u32 *aSz                        /* Sizes of each column, in tokens */
+){
+  char *pBlob;             /* The BLOB encoding of the document size */
+  int nBlob;               /* Number of bytes in the BLOB */
+  sqlite3_stmt *pStmt;     /* Statement used to insert the encoding */
+  int rc;                  /* Result code from subfunctions */
+
+  if( *pRC ) return;
+  pBlob = sqlite3_malloc( 10*p->nColumn );
+  if( pBlob==0 ){
+    *pRC = SQLITE_NOMEM;
+    return;
+  }
+  fts3EncodeIntArray(p->nColumn, aSz, pBlob, &nBlob);
+  rc = fts3SqlStmt(p, SQL_REPLACE_DOCSIZE, &pStmt, 0);
+  if( rc ){
+    sqlite3_free(pBlob);
+    *pRC = rc;
+    return;
+  }
+  sqlite3_bind_int64(pStmt, 1, p->iPrevDocid);
+  sqlite3_bind_blob(pStmt, 2, pBlob, nBlob, sqlite3_free);
+  sqlite3_step(pStmt);
+  *pRC = sqlite3_reset(pStmt);
+}
+
+/*
+** Record 0 of the %_stat table contains a blob consisting of N varints,
+** where N is the number of user defined columns in the fts3 table plus
+** two. If nCol is the number of user defined columns, then values of the 
+** varints are set as follows:
+**
+**   Varint 0:       Total number of rows in the table.
+**
+**   Varint 1..nCol: For each column, the total number of tokens stored in
+**                   the column for all rows of the table.
+**
+**   Varint 1+nCol:  The total size, in bytes, of all text values in all
+**                   columns of all rows of the table.
+**
+*/
+static void fts3UpdateDocTotals(
+  int *pRC,                       /* The result code */
+  Fts3Table *p,                   /* Table being updated */
+  u32 *aSzIns,                    /* Size increases */
+  u32 *aSzDel,                    /* Size decreases */
+  int nChng                       /* Change in the number of documents */
+){
+  char *pBlob;             /* Storage for BLOB written into %_stat */
+  int nBlob;               /* Size of BLOB written into %_stat */
+  u32 *a;                  /* Array of integers that becomes the BLOB */
+  sqlite3_stmt *pStmt;     /* Statement for reading and writing */
+  int i;                   /* Loop counter */
+  int rc;                  /* Result code from subfunctions */
+
+  const int nStat = p->nColumn+2;
+
+  if( *pRC ) return;
+  a = sqlite3_malloc( (sizeof(u32)+10)*nStat );
+  if( a==0 ){
+    *pRC = SQLITE_NOMEM;
+    return;
+  }
+  pBlob = (char*)&a[nStat];
+  rc = fts3SqlStmt(p, SQL_SELECT_STAT, &pStmt, 0);
+  if( rc ){
+    sqlite3_free(a);
+    *pRC = rc;
+    return;
+  }
+  sqlite3_bind_int(pStmt, 1, FTS_STAT_DOCTOTAL);
+  if( sqlite3_step(pStmt)==SQLITE_ROW ){
+    fts3DecodeIntArray(nStat, a,
+         sqlite3_column_blob(pStmt, 0),
+         sqlite3_column_bytes(pStmt, 0));
+  }else{
+    memset(a, 0, sizeof(u32)*(nStat) );
+  }
+  rc = sqlite3_reset(pStmt);
+  if( rc!=SQLITE_OK ){
+    sqlite3_free(a);
+    *pRC = rc;
+    return;
+  }
+  if( nChng<0 && a[0]<(u32)(-nChng) ){
+    a[0] = 0;
+  }else{
+    a[0] += nChng;
+  }
+  for(i=0; i<p->nColumn+1; i++){
+    u32 x = a[i+1];
+    if( x+aSzIns[i] < aSzDel[i] ){
+      x = 0;
+    }else{
+      x = x + aSzIns[i] - aSzDel[i];
+    }
+    a[i+1] = x;
+  }
+  fts3EncodeIntArray(nStat, a, pBlob, &nBlob);
+  rc = fts3SqlStmt(p, SQL_REPLACE_STAT, &pStmt, 0);
+  if( rc ){
+    sqlite3_free(a);
+    *pRC = rc;
+    return;
+  }
+  sqlite3_bind_int(pStmt, 1, FTS_STAT_DOCTOTAL);
+  sqlite3_bind_blob(pStmt, 2, pBlob, nBlob, SQLITE_STATIC);
+  sqlite3_step(pStmt);
+  *pRC = sqlite3_reset(pStmt);
+  sqlite3_free(a);
+}
+
+/*
+** Merge the entire database so that there is one segment for each 
+** iIndex/iLangid combination.
+*/
+static int fts3DoOptimize(Fts3Table *p, int bReturnDone){
+  int bSeenDone = 0;
+  int rc;
+  sqlite3_stmt *pAllLangid = 0;
+
+  rc = fts3SqlStmt(p, SQL_SELECT_ALL_LANGID, &pAllLangid, 0);
+  if( rc==SQLITE_OK ){
+    int rc2;
+    sqlite3_bind_int(pAllLangid, 1, p->iPrevLangid);
+    sqlite3_bind_int(pAllLangid, 2, p->nIndex);
+    while( sqlite3_step(pAllLangid)==SQLITE_ROW ){
+      int i;
+      int iLangid = sqlite3_column_int(pAllLangid, 0);
+      for(i=0; rc==SQLITE_OK && i<p->nIndex; i++){
+        rc = fts3SegmentMerge(p, iLangid, i, FTS3_SEGCURSOR_ALL);
+        if( rc==SQLITE_DONE ){
+          bSeenDone = 1;
+          rc = SQLITE_OK;
+        }
+      }
+    }
+    rc2 = sqlite3_reset(pAllLangid);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }
+
+  sqlite3Fts3SegmentsClose(p);
+  sqlite3Fts3PendingTermsClear(p);
+
+  return (rc==SQLITE_OK && bReturnDone && bSeenDone) ? SQLITE_DONE : rc;
+}
+
+/*
+** This function is called when the user executes the following statement:
+**
+**     INSERT INTO <tbl>(<tbl>) VALUES('rebuild');
+**
+** The entire FTS index is discarded and rebuilt. If the table is one 
+** created using the content=xxx option, then the new index is based on
+** the current contents of the xxx table. Otherwise, it is rebuilt based
+** on the contents of the %_content table.
+*/
+static int fts3DoRebuild(Fts3Table *p){
+  int rc;                         /* Return Code */
+
+  rc = fts3DeleteAll(p, 0);
+  if( rc==SQLITE_OK ){
+    u32 *aSz = 0;
+    u32 *aSzIns = 0;
+    u32 *aSzDel = 0;
+    sqlite3_stmt *pStmt = 0;
+    int nEntry = 0;
+
+    /* Compose and prepare an SQL statement to loop through the content table */
+    char *zSql = sqlite3_mprintf("SELECT %s" , p->zReadExprlist);
+    if( !zSql ){
+      rc = SQLITE_NOMEM;
+    }else{
+      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pStmt, 0);
+      sqlite3_free(zSql);
+    }
+
+    if( rc==SQLITE_OK ){
+      int nByte = sizeof(u32) * (p->nColumn+1)*3;
+      aSz = (u32 *)sqlite3_malloc(nByte);
+      if( aSz==0 ){
+        rc = SQLITE_NOMEM;
+      }else{
+        memset(aSz, 0, nByte);
+        aSzIns = &aSz[p->nColumn+1];
+        aSzDel = &aSzIns[p->nColumn+1];
+      }
+    }
+
+    while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
+      int iCol;
+      int iLangid = langidFromSelect(p, pStmt);
+      rc = fts3PendingTermsDocid(p, 0, iLangid, sqlite3_column_int64(pStmt, 0));
+      memset(aSz, 0, sizeof(aSz[0]) * (p->nColumn+1));
+      for(iCol=0; rc==SQLITE_OK && iCol<p->nColumn; iCol++){
+        if( p->abNotindexed[iCol]==0 ){
+          const char *z = (const char *) sqlite3_column_text(pStmt, iCol+1);
+          rc = fts3PendingTermsAdd(p, iLangid, z, iCol, &aSz[iCol]);
+          aSz[p->nColumn] += sqlite3_column_bytes(pStmt, iCol+1);
+        }
+      }
+      if( p->bHasDocsize ){
+        fts3InsertDocsize(&rc, p, aSz);
+      }
+      if( rc!=SQLITE_OK ){
+        sqlite3_finalize(pStmt);
+        pStmt = 0;
+      }else{
+        nEntry++;
+        for(iCol=0; iCol<=p->nColumn; iCol++){
+          aSzIns[iCol] += aSz[iCol];
+        }
+      }
+    }
+    if( p->bFts4 ){
+      fts3UpdateDocTotals(&rc, p, aSzIns, aSzDel, nEntry);
+    }
+    sqlite3_free(aSz);
+
+    if( pStmt ){
+      int rc2 = sqlite3_finalize(pStmt);
+      if( rc==SQLITE_OK ){
+        rc = rc2;
+      }
+    }
+  }
+
+  return rc;
+}
+
+
+/*
+** This function opens a cursor used to read the input data for an 
+** incremental merge operation. Specifically, it opens a cursor to scan
+** the oldest nSeg segments (idx=0 through idx=(nSeg-1)) in absolute 
+** level iAbsLevel.
+*/
+static int fts3IncrmergeCsr(
+  Fts3Table *p,                   /* FTS3 table handle */
+  sqlite3_int64 iAbsLevel,        /* Absolute level to open */
+  int nSeg,                       /* Number of segments to merge */
+  Fts3MultiSegReader *pCsr        /* Cursor object to populate */
+){
+  int rc;                         /* Return Code */
+  sqlite3_stmt *pStmt = 0;        /* Statement used to read %_segdir entry */  
+  int nByte;                      /* Bytes allocated at pCsr->apSegment[] */
+
+  /* Allocate space for the Fts3MultiSegReader.aCsr[] array */
+  memset(pCsr, 0, sizeof(*pCsr));
+  nByte = sizeof(Fts3SegReader *) * nSeg;
+  pCsr->apSegment = (Fts3SegReader **)sqlite3_malloc(nByte);
+
+  if( pCsr->apSegment==0 ){
+    rc = SQLITE_NOMEM;
+  }else{
+    memset(pCsr->apSegment, 0, nByte);
+    rc = fts3SqlStmt(p, SQL_SELECT_LEVEL, &pStmt, 0);
+  }
+  if( rc==SQLITE_OK ){
+    int i;
+    int rc2;
+    sqlite3_bind_int64(pStmt, 1, iAbsLevel);
+    assert( pCsr->nSegment==0 );
+    for(i=0; rc==SQLITE_OK && sqlite3_step(pStmt)==SQLITE_ROW && i<nSeg; i++){
+      rc = sqlite3Fts3SegReaderNew(i, 0,
+          sqlite3_column_int64(pStmt, 1),        /* segdir.start_block */
+          sqlite3_column_int64(pStmt, 2),        /* segdir.leaves_end_block */
+          sqlite3_column_int64(pStmt, 3),        /* segdir.end_block */
+          sqlite3_column_blob(pStmt, 4),         /* segdir.root */
+          sqlite3_column_bytes(pStmt, 4),        /* segdir.root */
+          &pCsr->apSegment[i]
+      );
+      pCsr->nSegment++;
+    }
+    rc2 = sqlite3_reset(pStmt);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }
+
+  return rc;
+}
+
+typedef struct IncrmergeWriter IncrmergeWriter;
+typedef struct NodeWriter NodeWriter;
+typedef struct Blob Blob;
+typedef struct NodeReader NodeReader;
+
+/*
+** An instance of the following structure is used as a dynamic buffer
+** to build up nodes or other blobs of data in.
+**
+** The function blobGrowBuffer() is used to extend the allocation.
+*/
+struct Blob {
+  char *a;                        /* Pointer to allocation */
+  int n;                          /* Number of valid bytes of data in a[] */
+  int nAlloc;                     /* Allocated size of a[] (nAlloc>=n) */
+};
+
+/*
+** This structure is used to build up buffers containing segment b-tree 
+** nodes (blocks).
+*/
+struct NodeWriter {
+  sqlite3_int64 iBlock;           /* Current block id */
+  Blob key;                       /* Last key written to the current block */
+  Blob block;                     /* Current block image */
+};
+
+/*
+** An object of this type contains the state required to create or append
+** to an appendable b-tree segment.
+*/
+struct IncrmergeWriter {
+  int nLeafEst;                   /* Space allocated for leaf blocks */
+  int nWork;                      /* Number of leaf pages flushed */
+  sqlite3_int64 iAbsLevel;        /* Absolute level of input segments */
+  int iIdx;                       /* Index of *output* segment in iAbsLevel+1 */
+  sqlite3_int64 iStart;           /* Block number of first allocated block */
+  sqlite3_int64 iEnd;             /* Block number of last allocated block */
+  sqlite3_int64 nLeafData;        /* Bytes of leaf page data so far */
+  u8 bNoLeafData;                 /* If true, store 0 for segment size */
+  NodeWriter aNodeWriter[FTS_MAX_APPENDABLE_HEIGHT];
+};
+
+/*
+** An object of the following type is used to read data from a single
+** FTS segment node. See the following functions:
+**
+**     nodeReaderInit()
+**     nodeReaderNext()
+**     nodeReaderRelease()
+*/
+struct NodeReader {
+  const char *aNode;
+  int nNode;
+  int iOff;                       /* Current offset within aNode[] */
+
+  /* Output variables. Containing the current node entry. */
+  sqlite3_int64 iChild;           /* Pointer to child node */
+  Blob term;                      /* Current term */
+  const char *aDoclist;           /* Pointer to doclist */
+  int nDoclist;                   /* Size of doclist in bytes */
+};
+
+/*
+** If *pRc is not SQLITE_OK when this function is called, it is a no-op.
+** Otherwise, if the allocation at pBlob->a is not already at least nMin
+** bytes in size, extend (realloc) it to be so.
+**
+** If an OOM error occurs, set *pRc to SQLITE_NOMEM and leave pBlob->a
+** unmodified. Otherwise, if the allocation succeeds, update pBlob->nAlloc
+** to reflect the new size of the pBlob->a[] buffer.
+*/
+static void blobGrowBuffer(Blob *pBlob, int nMin, int *pRc){
+  if( *pRc==SQLITE_OK && nMin>pBlob->nAlloc ){
+    int nAlloc = nMin;
+    char *a = (char *)sqlite3_realloc(pBlob->a, nAlloc);
+    if( a ){
+      pBlob->nAlloc = nAlloc;
+      pBlob->a = a;
+    }else{
+      *pRc = SQLITE_NOMEM;
+    }
+  }
+}
+
+/*
+** Attempt to advance the node-reader object passed as the first argument to
+** the next entry on the node. 
+**
+** Return an error code if an error occurs (SQLITE_NOMEM is possible). 
+** Otherwise return SQLITE_OK. If there is no next entry on the node
+** (e.g. because the current entry is the last) set NodeReader->aNode to
+** NULL to indicate EOF. Otherwise, populate the NodeReader structure output 
+** variables for the new entry.
+*/
+static int nodeReaderNext(NodeReader *p){
+  int bFirst = (p->term.n==0);    /* True for first term on the node */
+  int nPrefix = 0;                /* Bytes to copy from previous term */
+  int nSuffix = 0;                /* Bytes to append to the prefix */
+  int rc = SQLITE_OK;             /* Return code */
+
+  assert( p->aNode );
+  if( p->iChild && bFirst==0 ) p->iChild++;
+  if( p->iOff>=p->nNode ){
+    /* EOF */
+    p->aNode = 0;
+  }else{
+    if( bFirst==0 ){
+      p->iOff += fts3GetVarint32(&p->aNode[p->iOff], &nPrefix);
+    }
+    p->iOff += fts3GetVarint32(&p->aNode[p->iOff], &nSuffix);
+
+    blobGrowBuffer(&p->term, nPrefix+nSuffix, &rc);
+    if( rc==SQLITE_OK ){
+      memcpy(&p->term.a[nPrefix], &p->aNode[p->iOff], nSuffix);
+      p->term.n = nPrefix+nSuffix;
+      p->iOff += nSuffix;
+      if( p->iChild==0 ){
+        p->iOff += fts3GetVarint32(&p->aNode[p->iOff], &p->nDoclist);
+        p->aDoclist = &p->aNode[p->iOff];
+        p->iOff += p->nDoclist;
+      }
+    }
+  }
+
+  assert( p->iOff<=p->nNode );
+
+  return rc;
+}
+
+/*
+** Release all dynamic resources held by node-reader object *p.
+*/
+static void nodeReaderRelease(NodeReader *p){
+  sqlite3_free(p->term.a);
+}
+
+/*
+** Initialize a node-reader object to read the node in buffer aNode/nNode.
+**
+** If successful, SQLITE_OK is returned and the NodeReader object set to 
+** point to the first entry on the node (if any). Otherwise, an SQLite
+** error code is returned.
+*/
+static int nodeReaderInit(NodeReader *p, const char *aNode, int nNode){
+  memset(p, 0, sizeof(NodeReader));
+  p->aNode = aNode;
+  p->nNode = nNode;
+
+  /* Figure out if this is a leaf or an internal node. */
+  if( p->aNode[0] ){
+    /* An internal node. */
+    p->iOff = 1 + sqlite3Fts3GetVarint(&p->aNode[1], &p->iChild);
+  }else{
+    p->iOff = 1;
+  }
+
+  return nodeReaderNext(p);
+}
+
+/*
+** This function is called while writing an FTS segment each time a leaf o
+** node is finished and written to disk. The key (zTerm/nTerm) is guaranteed
+** to be greater than the largest key on the node just written, but smaller
+** than or equal to the first key that will be written to the next leaf
+** node.
+**
+** The block id of the leaf node just written to disk may be found in
+** (pWriter->aNodeWriter[0].iBlock) when this function is called.
+*/
+static int fts3IncrmergePush(
+  Fts3Table *p,                   /* Fts3 table handle */
+  IncrmergeWriter *pWriter,       /* Writer object */
+  const char *zTerm,              /* Term to write to internal node */
+  int nTerm                       /* Bytes at zTerm */
+){
+  sqlite3_int64 iPtr = pWriter->aNodeWriter[0].iBlock;
+  int iLayer;
+
+  assert( nTerm>0 );
+  for(iLayer=1; ALWAYS(iLayer<FTS_MAX_APPENDABLE_HEIGHT); iLayer++){
+    sqlite3_int64 iNextPtr = 0;
+    NodeWriter *pNode = &pWriter->aNodeWriter[iLayer];
+    int rc = SQLITE_OK;
+    int nPrefix;
+    int nSuffix;
+    int nSpace;
+
+    /* Figure out how much space the key will consume if it is written to
+    ** the current node of layer iLayer. Due to the prefix compression, 
+    ** the space required changes depending on which node the key is to
+    ** be added to.  */
+    nPrefix = fts3PrefixCompress(pNode->key.a, pNode->key.n, zTerm, nTerm);
+    nSuffix = nTerm - nPrefix;
+    nSpace  = sqlite3Fts3VarintLen(nPrefix);
+    nSpace += sqlite3Fts3VarintLen(nSuffix) + nSuffix;
+
+    if( pNode->key.n==0 || (pNode->block.n + nSpace)<=p->nNodeSize ){ 
+      /* If the current node of layer iLayer contains zero keys, or if adding
+      ** the key to it will not cause it to grow to larger than nNodeSize 
+      ** bytes in size, write the key here.  */
+
+      Blob *pBlk = &pNode->block;
+      if( pBlk->n==0 ){
+        blobGrowBuffer(pBlk, p->nNodeSize, &rc);
+        if( rc==SQLITE_OK ){
+          pBlk->a[0] = (char)iLayer;
+          pBlk->n = 1 + sqlite3Fts3PutVarint(&pBlk->a[1], iPtr);
+        }
+      }
+      blobGrowBuffer(pBlk, pBlk->n + nSpace, &rc);
+      blobGrowBuffer(&pNode->key, nTerm, &rc);
+
+      if( rc==SQLITE_OK ){
+        if( pNode->key.n ){
+          pBlk->n += sqlite3Fts3PutVarint(&pBlk->a[pBlk->n], nPrefix);
+        }
+        pBlk->n += sqlite3Fts3PutVarint(&pBlk->a[pBlk->n], nSuffix);
+        memcpy(&pBlk->a[pBlk->n], &zTerm[nPrefix], nSuffix);
+        pBlk->n += nSuffix;
+
+        memcpy(pNode->key.a, zTerm, nTerm);
+        pNode->key.n = nTerm;
+      }
+    }else{
+      /* Otherwise, flush the current node of layer iLayer to disk.
+      ** Then allocate a new, empty sibling node. The key will be written
+      ** into the parent of this node. */
+      rc = fts3WriteSegment(p, pNode->iBlock, pNode->block.a, pNode->block.n);
+
+      assert( pNode->block.nAlloc>=p->nNodeSize );
+      pNode->block.a[0] = (char)iLayer;
+      pNode->block.n = 1 + sqlite3Fts3PutVarint(&pNode->block.a[1], iPtr+1);
+
+      iNextPtr = pNode->iBlock;
+      pNode->iBlock++;
+      pNode->key.n = 0;
+    }
+
+    if( rc!=SQLITE_OK || iNextPtr==0 ) return rc;
+    iPtr = iNextPtr;
+  }
+
+  assert( 0 );
+  return 0;
+}
+
+/*
+** Append a term and (optionally) doclist to the FTS segment node currently
+** stored in blob *pNode. The node need not contain any terms, but the
+** header must be written before this function is called.
+**
+** A node header is a single 0x00 byte for a leaf node, or a height varint
+** followed by the left-hand-child varint for an internal node.
+**
+** The term to be appended is passed via arguments zTerm/nTerm. For a 
+** leaf node, the doclist is passed as aDoclist/nDoclist. For an internal
+** node, both aDoclist and nDoclist must be passed 0.
+**
+** If the size of the value in blob pPrev is zero, then this is the first
+** term written to the node. Otherwise, pPrev contains a copy of the 
+** previous term. Before this function returns, it is updated to contain a
+** copy of zTerm/nTerm.
+**
+** It is assumed that the buffer associated with pNode is already large
+** enough to accommodate the new entry. The buffer associated with pPrev
+** is extended by this function if requrired.
+**
+** If an error (i.e. OOM condition) occurs, an SQLite error code is
+** returned. Otherwise, SQLITE_OK.
+*/
+static int fts3AppendToNode(
+  Blob *pNode,                    /* Current node image to append to */
+  Blob *pPrev,                    /* Buffer containing previous term written */
+  const char *zTerm,              /* New term to write */
+  int nTerm,                      /* Size of zTerm in bytes */
+  const char *aDoclist,           /* Doclist (or NULL) to write */
+  int nDoclist                    /* Size of aDoclist in bytes */ 
+){
+  int rc = SQLITE_OK;             /* Return code */
+  int bFirst = (pPrev->n==0);     /* True if this is the first term written */
+  int nPrefix;                    /* Size of term prefix in bytes */
+  int nSuffix;                    /* Size of term suffix in bytes */
+
+  /* Node must have already been started. There must be a doclist for a
+  ** leaf node, and there must not be a doclist for an internal node.  */
+  assert( pNode->n>0 );
+  assert( (pNode->a[0]=='\0')==(aDoclist!=0) );
+
+  blobGrowBuffer(pPrev, nTerm, &rc);
+  if( rc!=SQLITE_OK ) return rc;
+
+  nPrefix = fts3PrefixCompress(pPrev->a, pPrev->n, zTerm, nTerm);
+  nSuffix = nTerm - nPrefix;
+  memcpy(pPrev->a, zTerm, nTerm);
+  pPrev->n = nTerm;
+
+  if( bFirst==0 ){
+    pNode->n += sqlite3Fts3PutVarint(&pNode->a[pNode->n], nPrefix);
+  }
+  pNode->n += sqlite3Fts3PutVarint(&pNode->a[pNode->n], nSuffix);
+  memcpy(&pNode->a[pNode->n], &zTerm[nPrefix], nSuffix);
+  pNode->n += nSuffix;
+
+  if( aDoclist ){
+    pNode->n += sqlite3Fts3PutVarint(&pNode->a[pNode->n], nDoclist);
+    memcpy(&pNode->a[pNode->n], aDoclist, nDoclist);
+    pNode->n += nDoclist;
+  }
+
+  assert( pNode->n<=pNode->nAlloc );
+
+  return SQLITE_OK;
+}
+
+/*
+** Append the current term and doclist pointed to by cursor pCsr to the
+** appendable b-tree segment opened for writing by pWriter.
+**
+** Return SQLITE_OK if successful, or an SQLite error code otherwise.
+*/
+static int fts3IncrmergeAppend(
+  Fts3Table *p,                   /* Fts3 table handle */
+  IncrmergeWriter *pWriter,       /* Writer object */
+  Fts3MultiSegReader *pCsr        /* Cursor containing term and doclist */
+){
+  const char *zTerm = pCsr->zTerm;
+  int nTerm = pCsr->nTerm;
+  const char *aDoclist = pCsr->aDoclist;
+  int nDoclist = pCsr->nDoclist;
+  int rc = SQLITE_OK;           /* Return code */
+  int nSpace;                   /* Total space in bytes required on leaf */
+  int nPrefix;                  /* Size of prefix shared with previous term */
+  int nSuffix;                  /* Size of suffix (nTerm - nPrefix) */
+  NodeWriter *pLeaf;            /* Object used to write leaf nodes */
+
+  pLeaf = &pWriter->aNodeWriter[0];
+  nPrefix = fts3PrefixCompress(pLeaf->key.a, pLeaf->key.n, zTerm, nTerm);
+  nSuffix = nTerm - nPrefix;
+
+  nSpace  = sqlite3Fts3VarintLen(nPrefix);
+  nSpace += sqlite3Fts3VarintLen(nSuffix) + nSuffix;
+  nSpace += sqlite3Fts3VarintLen(nDoclist) + nDoclist;
+
+  /* If the current block is not empty, and if adding this term/doclist
+  ** to the current block would make it larger than Fts3Table.nNodeSize
+  ** bytes, write this block out to the database. */
+  if( pLeaf->block.n>0 && (pLeaf->block.n + nSpace)>p->nNodeSize ){
+    rc = fts3WriteSegment(p, pLeaf->iBlock, pLeaf->block.a, pLeaf->block.n);
+    pWriter->nWork++;
+
+    /* Add the current term to the parent node. The term added to the 
+    ** parent must:
+    **
+    **   a) be greater than the largest term on the leaf node just written
+    **      to the database (still available in pLeaf->key), and
+    **
+    **   b) be less than or equal to the term about to be added to the new
+    **      leaf node (zTerm/nTerm).
+    **
+    ** In other words, it must be the prefix of zTerm 1 byte longer than
+    ** the common prefix (if any) of zTerm and pWriter->zTerm.
+    */
+    if( rc==SQLITE_OK ){
+      rc = fts3IncrmergePush(p, pWriter, zTerm, nPrefix+1);
+    }
+
+    /* Advance to the next output block */
+    pLeaf->iBlock++;
+    pLeaf->key.n = 0;
+    pLeaf->block.n = 0;
+
+    nSuffix = nTerm;
+    nSpace  = 1;
+    nSpace += sqlite3Fts3VarintLen(nSuffix) + nSuffix;
+    nSpace += sqlite3Fts3VarintLen(nDoclist) + nDoclist;
+  }
+
+  pWriter->nLeafData += nSpace;
+  blobGrowBuffer(&pLeaf->block, pLeaf->block.n + nSpace, &rc);
+  if( rc==SQLITE_OK ){
+    if( pLeaf->block.n==0 ){
+      pLeaf->block.n = 1;
+      pLeaf->block.a[0] = '\0';
+    }
+    rc = fts3AppendToNode(
+        &pLeaf->block, &pLeaf->key, zTerm, nTerm, aDoclist, nDoclist
+    );
+  }
+
+  return rc;
+}
+
+/*
+** This function is called to release all dynamic resources held by the
+** merge-writer object pWriter, and if no error has occurred, to flush
+** all outstanding node buffers held by pWriter to disk.
+**
+** If *pRc is not SQLITE_OK when this function is called, then no attempt
+** is made to write any data to disk. Instead, this function serves only
+** to release outstanding resources.
+**
+** Otherwise, if *pRc is initially SQLITE_OK and an error occurs while
+** flushing buffers to disk, *pRc is set to an SQLite error code before
+** returning.
+*/
+static void fts3IncrmergeRelease(
+  Fts3Table *p,                   /* FTS3 table handle */
+  IncrmergeWriter *pWriter,       /* Merge-writer object */
+  int *pRc                        /* IN/OUT: Error code */
+){
+  int i;                          /* Used to iterate through non-root layers */
+  int iRoot;                      /* Index of root in pWriter->aNodeWriter */
+  NodeWriter *pRoot;              /* NodeWriter for root node */
+  int rc = *pRc;                  /* Error code */
+
+  /* Set iRoot to the index in pWriter->aNodeWriter[] of the output segment 
+  ** root node. If the segment fits entirely on a single leaf node, iRoot
+  ** will be set to 0. If the root node is the parent of the leaves, iRoot
+  ** will be 1. And so on.  */
+  for(iRoot=FTS_MAX_APPENDABLE_HEIGHT-1; iRoot>=0; iRoot--){
+    NodeWriter *pNode = &pWriter->aNodeWriter[iRoot];
+    if( pNode->block.n>0 ) break;
+    assert( *pRc || pNode->block.nAlloc==0 );
+    assert( *pRc || pNode->key.nAlloc==0 );
+    sqlite3_free(pNode->block.a);
+    sqlite3_free(pNode->key.a);
+  }
+
+  /* Empty output segment. This is a no-op. */
+  if( iRoot<0 ) return;
+
+  /* The entire output segment fits on a single node. Normally, this means
+  ** the node would be stored as a blob in the "root" column of the %_segdir
+  ** table. However, this is not permitted in this case. The problem is that 
+  ** space has already been reserved in the %_segments table, and so the 
+  ** start_block and end_block fields of the %_segdir table must be populated. 
+  ** And, by design or by accident, released versions of FTS cannot handle 
+  ** segments that fit entirely on the root node with start_block!=0.
+  **
+  ** Instead, create a synthetic root node that contains nothing but a 
+  ** pointer to the single content node. So that the segment consists of a
+  ** single leaf and a single interior (root) node.
+  **
+  ** Todo: Better might be to defer allocating space in the %_segments 
+  ** table until we are sure it is needed.
+  */
+  if( iRoot==0 ){
+    Blob *pBlock = &pWriter->aNodeWriter[1].block;
+    blobGrowBuffer(pBlock, 1 + FTS3_VARINT_MAX, &rc);
+    if( rc==SQLITE_OK ){
+      pBlock->a[0] = 0x01;
+      pBlock->n = 1 + sqlite3Fts3PutVarint(
+          &pBlock->a[1], pWriter->aNodeWriter[0].iBlock
+      );
+    }
+    iRoot = 1;
+  }
+  pRoot = &pWriter->aNodeWriter[iRoot];
+
+  /* Flush all currently outstanding nodes to disk. */
+  for(i=0; i<iRoot; i++){
+    NodeWriter *pNode = &pWriter->aNodeWriter[i];
+    if( pNode->block.n>0 && rc==SQLITE_OK ){
+      rc = fts3WriteSegment(p, pNode->iBlock, pNode->block.a, pNode->block.n);
+    }
+    sqlite3_free(pNode->block.a);
+    sqlite3_free(pNode->key.a);
+  }
+
+  /* Write the %_segdir record. */
+  if( rc==SQLITE_OK ){
+    rc = fts3WriteSegdir(p, 
+        pWriter->iAbsLevel+1,               /* level */
+        pWriter->iIdx,                      /* idx */
+        pWriter->iStart,                    /* start_block */
+        pWriter->aNodeWriter[0].iBlock,     /* leaves_end_block */
+        pWriter->iEnd,                      /* end_block */
+        (pWriter->bNoLeafData==0 ? pWriter->nLeafData : 0),   /* end_block */
+        pRoot->block.a, pRoot->block.n      /* root */
+    );
+  }
+  sqlite3_free(pRoot->block.a);
+  sqlite3_free(pRoot->key.a);
+
+  *pRc = rc;
+}
+
+/*
+** Compare the term in buffer zLhs (size in bytes nLhs) with that in
+** zRhs (size in bytes nRhs) using memcmp. If one term is a prefix of
+** the other, it is considered to be smaller than the other.
+**
+** Return -ve if zLhs is smaller than zRhs, 0 if it is equal, or +ve
+** if it is greater.
+*/
+static int fts3TermCmp(
+  const char *zLhs, int nLhs,     /* LHS of comparison */
+  const char *zRhs, int nRhs      /* RHS of comparison */
+){
+  int nCmp = MIN(nLhs, nRhs);
+  int res;
+
+  res = memcmp(zLhs, zRhs, nCmp);
+  if( res==0 ) res = nLhs - nRhs;
+
+  return res;
+}
+
+
+/*
+** Query to see if the entry in the %_segments table with blockid iEnd is 
+** NULL. If no error occurs and the entry is NULL, set *pbRes 1 before
+** returning. Otherwise, set *pbRes to 0. 
+**
+** Or, if an error occurs while querying the database, return an SQLite 
+** error code. The final value of *pbRes is undefined in this case.
+**
+** This is used to test if a segment is an "appendable" segment. If it
+** is, then a NULL entry has been inserted into the %_segments table
+** with blockid %_segdir.end_block.
+*/
+static int fts3IsAppendable(Fts3Table *p, sqlite3_int64 iEnd, int *pbRes){
+  int bRes = 0;                   /* Result to set *pbRes to */
+  sqlite3_stmt *pCheck = 0;       /* Statement to query database with */
+  int rc;                         /* Return code */
+
+  rc = fts3SqlStmt(p, SQL_SEGMENT_IS_APPENDABLE, &pCheck, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int64(pCheck, 1, iEnd);
+    if( SQLITE_ROW==sqlite3_step(pCheck) ) bRes = 1;
+    rc = sqlite3_reset(pCheck);
+  }
+  
+  *pbRes = bRes;
+  return rc;
+}
+
+/*
+** This function is called when initializing an incremental-merge operation.
+** It checks if the existing segment with index value iIdx at absolute level 
+** (iAbsLevel+1) can be appended to by the incremental merge. If it can, the
+** merge-writer object *pWriter is initialized to write to it.
+**
+** An existing segment can be appended to by an incremental merge if:
+**
+**   * It was initially created as an appendable segment (with all required
+**     space pre-allocated), and
+**
+**   * The first key read from the input (arguments zKey and nKey) is 
+**     greater than the largest key currently stored in the potential
+**     output segment.
+*/
+static int fts3IncrmergeLoad(
+  Fts3Table *p,                   /* Fts3 table handle */
+  sqlite3_int64 iAbsLevel,        /* Absolute level of input segments */
+  int iIdx,                       /* Index of candidate output segment */
+  const char *zKey,               /* First key to write */
+  int nKey,                       /* Number of bytes in nKey */
+  IncrmergeWriter *pWriter        /* Populate this object */
+){
+  int rc;                         /* Return code */
+  sqlite3_stmt *pSelect = 0;      /* SELECT to read %_segdir entry */
+
+  rc = fts3SqlStmt(p, SQL_SELECT_SEGDIR, &pSelect, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_int64 iStart = 0;     /* Value of %_segdir.start_block */
+    sqlite3_int64 iLeafEnd = 0;   /* Value of %_segdir.leaves_end_block */
+    sqlite3_int64 iEnd = 0;       /* Value of %_segdir.end_block */
+    const char *aRoot = 0;        /* Pointer to %_segdir.root buffer */
+    int nRoot = 0;                /* Size of aRoot[] in bytes */
+    int rc2;                      /* Return code from sqlite3_reset() */
+    int bAppendable = 0;          /* Set to true if segment is appendable */
+
+    /* Read the %_segdir entry for index iIdx absolute level (iAbsLevel+1) */
+    sqlite3_bind_int64(pSelect, 1, iAbsLevel+1);
+    sqlite3_bind_int(pSelect, 2, iIdx);
+    if( sqlite3_step(pSelect)==SQLITE_ROW ){
+      iStart = sqlite3_column_int64(pSelect, 1);
+      iLeafEnd = sqlite3_column_int64(pSelect, 2);
+      fts3ReadEndBlockField(pSelect, 3, &iEnd, &pWriter->nLeafData);
+      if( pWriter->nLeafData<0 ){
+        pWriter->nLeafData = pWriter->nLeafData * -1;
+      }
+      pWriter->bNoLeafData = (pWriter->nLeafData==0);
+      nRoot = sqlite3_column_bytes(pSelect, 4);
+      aRoot = sqlite3_column_blob(pSelect, 4);
+    }else{
+      return sqlite3_reset(pSelect);
+    }
+
+    /* Check for the zero-length marker in the %_segments table */
+    rc = fts3IsAppendable(p, iEnd, &bAppendable);
+
+    /* Check that zKey/nKey is larger than the largest key the candidate */
+    if( rc==SQLITE_OK && bAppendable ){
+      char *aLeaf = 0;
+      int nLeaf = 0;
+
+      rc = sqlite3Fts3ReadBlock(p, iLeafEnd, &aLeaf, &nLeaf, 0);
+      if( rc==SQLITE_OK ){
+        NodeReader reader;
+        for(rc = nodeReaderInit(&reader, aLeaf, nLeaf);
+            rc==SQLITE_OK && reader.aNode;
+            rc = nodeReaderNext(&reader)
+        ){
+          assert( reader.aNode );
+        }
+        if( fts3TermCmp(zKey, nKey, reader.term.a, reader.term.n)<=0 ){
+          bAppendable = 0;
+        }
+        nodeReaderRelease(&reader);
+      }
+      sqlite3_free(aLeaf);
+    }
+
+    if( rc==SQLITE_OK && bAppendable ){
+      /* It is possible to append to this segment. Set up the IncrmergeWriter
+      ** object to do so.  */
+      int i;
+      int nHeight = (int)aRoot[0];
+      NodeWriter *pNode;
+
+      pWriter->nLeafEst = (int)((iEnd - iStart) + 1)/FTS_MAX_APPENDABLE_HEIGHT;
+      pWriter->iStart = iStart;
+      pWriter->iEnd = iEnd;
+      pWriter->iAbsLevel = iAbsLevel;
+      pWriter->iIdx = iIdx;
+
+      for(i=nHeight+1; i<FTS_MAX_APPENDABLE_HEIGHT; i++){
+        pWriter->aNodeWriter[i].iBlock = pWriter->iStart + i*pWriter->nLeafEst;
+      }
+
+      pNode = &pWriter->aNodeWriter[nHeight];
+      pNode->iBlock = pWriter->iStart + pWriter->nLeafEst*nHeight;
+      blobGrowBuffer(&pNode->block, MAX(nRoot, p->nNodeSize), &rc);
+      if( rc==SQLITE_OK ){
+        memcpy(pNode->block.a, aRoot, nRoot);
+        pNode->block.n = nRoot;
+      }
+
+      for(i=nHeight; i>=0 && rc==SQLITE_OK; i--){
+        NodeReader reader;
+        pNode = &pWriter->aNodeWriter[i];
+
+        rc = nodeReaderInit(&reader, pNode->block.a, pNode->block.n);
+        while( reader.aNode && rc==SQLITE_OK ) rc = nodeReaderNext(&reader);
+        blobGrowBuffer(&pNode->key, reader.term.n, &rc);
+        if( rc==SQLITE_OK ){
+          memcpy(pNode->key.a, reader.term.a, reader.term.n);
+          pNode->key.n = reader.term.n;
+          if( i>0 ){
+            char *aBlock = 0;
+            int nBlock = 0;
+            pNode = &pWriter->aNodeWriter[i-1];
+            pNode->iBlock = reader.iChild;
+            rc = sqlite3Fts3ReadBlock(p, reader.iChild, &aBlock, &nBlock, 0);
+            blobGrowBuffer(&pNode->block, MAX(nBlock, p->nNodeSize), &rc);
+            if( rc==SQLITE_OK ){
+              memcpy(pNode->block.a, aBlock, nBlock);
+              pNode->block.n = nBlock;
+            }
+            sqlite3_free(aBlock);
+          }
+        }
+        nodeReaderRelease(&reader);
+      }
+    }
+
+    rc2 = sqlite3_reset(pSelect);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }
+
+  return rc;
+}
+
+/*
+** Determine the largest segment index value that exists within absolute
+** level iAbsLevel+1. If no error occurs, set *piIdx to this value plus
+** one before returning SQLITE_OK. Or, if there are no segments at all 
+** within level iAbsLevel, set *piIdx to zero.
+**
+** If an error occurs, return an SQLite error code. The final value of
+** *piIdx is undefined in this case.
+*/
+static int fts3IncrmergeOutputIdx( 
+  Fts3Table *p,                   /* FTS Table handle */
+  sqlite3_int64 iAbsLevel,        /* Absolute index of input segments */
+  int *piIdx                      /* OUT: Next free index at iAbsLevel+1 */
+){
+  int rc;
+  sqlite3_stmt *pOutputIdx = 0;   /* SQL used to find output index */
+
+  rc = fts3SqlStmt(p, SQL_NEXT_SEGMENT_INDEX, &pOutputIdx, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int64(pOutputIdx, 1, iAbsLevel+1);
+    sqlite3_step(pOutputIdx);
+    *piIdx = sqlite3_column_int(pOutputIdx, 0);
+    rc = sqlite3_reset(pOutputIdx);
+  }
+
+  return rc;
+}
+
+/* 
+** Allocate an appendable output segment on absolute level iAbsLevel+1
+** with idx value iIdx.
+**
+** In the %_segdir table, a segment is defined by the values in three
+** columns:
+**
+**     start_block
+**     leaves_end_block
+**     end_block
+**
+** When an appendable segment is allocated, it is estimated that the
+** maximum number of leaf blocks that may be required is the sum of the
+** number of leaf blocks consumed by the input segments, plus the number
+** of input segments, multiplied by two. This value is stored in stack 
+** variable nLeafEst.
+**
+** A total of 16*nLeafEst blocks are allocated when an appendable segment
+** is created ((1 + end_block - start_block)==16*nLeafEst). The contiguous
+** array of leaf nodes starts at the first block allocated. The array
+** of interior nodes that are parents of the leaf nodes start at block
+** (start_block + (1 + end_block - start_block) / 16). And so on.
+**
+** In the actual code below, the value "16" is replaced with the 
+** pre-processor macro FTS_MAX_APPENDABLE_HEIGHT.
+*/
+static int fts3IncrmergeWriter( 
+  Fts3Table *p,                   /* Fts3 table handle */
+  sqlite3_int64 iAbsLevel,        /* Absolute level of input segments */
+  int iIdx,                       /* Index of new output segment */
+  Fts3MultiSegReader *pCsr,       /* Cursor that data will be read from */
+  IncrmergeWriter *pWriter        /* Populate this object */
+){
+  int rc;                         /* Return Code */
+  int i;                          /* Iterator variable */
+  int nLeafEst = 0;               /* Blocks allocated for leaf nodes */
+  sqlite3_stmt *pLeafEst = 0;     /* SQL used to determine nLeafEst */
+  sqlite3_stmt *pFirstBlock = 0;  /* SQL used to determine first block */
+
+  /* Calculate nLeafEst. */
+  rc = fts3SqlStmt(p, SQL_MAX_LEAF_NODE_ESTIMATE, &pLeafEst, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int64(pLeafEst, 1, iAbsLevel);
+    sqlite3_bind_int64(pLeafEst, 2, pCsr->nSegment);
+    if( SQLITE_ROW==sqlite3_step(pLeafEst) ){
+      nLeafEst = sqlite3_column_int(pLeafEst, 0);
+    }
+    rc = sqlite3_reset(pLeafEst);
+  }
+  if( rc!=SQLITE_OK ) return rc;
+
+  /* Calculate the first block to use in the output segment */
+  rc = fts3SqlStmt(p, SQL_NEXT_SEGMENTS_ID, &pFirstBlock, 0);
+  if( rc==SQLITE_OK ){
+    if( SQLITE_ROW==sqlite3_step(pFirstBlock) ){
+      pWriter->iStart = sqlite3_column_int64(pFirstBlock, 0);
+      pWriter->iEnd = pWriter->iStart - 1;
+      pWriter->iEnd += nLeafEst * FTS_MAX_APPENDABLE_HEIGHT;
+    }
+    rc = sqlite3_reset(pFirstBlock);
+  }
+  if( rc!=SQLITE_OK ) return rc;
+
+  /* Insert the marker in the %_segments table to make sure nobody tries
+  ** to steal the space just allocated. This is also used to identify 
+  ** appendable segments.  */
+  rc = fts3WriteSegment(p, pWriter->iEnd, 0, 0);
+  if( rc!=SQLITE_OK ) return rc;
+
+  pWriter->iAbsLevel = iAbsLevel;
+  pWriter->nLeafEst = nLeafEst;
+  pWriter->iIdx = iIdx;
+
+  /* Set up the array of NodeWriter objects */
+  for(i=0; i<FTS_MAX_APPENDABLE_HEIGHT; i++){
+    pWriter->aNodeWriter[i].iBlock = pWriter->iStart + i*pWriter->nLeafEst;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Remove an entry from the %_segdir table. This involves running the 
+** following two statements:
+**
+**   DELETE FROM %_segdir WHERE level = :iAbsLevel AND idx = :iIdx
+**   UPDATE %_segdir SET idx = idx - 1 WHERE level = :iAbsLevel AND idx > :iIdx
+**
+** The DELETE statement removes the specific %_segdir level. The UPDATE 
+** statement ensures that the remaining segments have contiguously allocated
+** idx values.
+*/
+static int fts3RemoveSegdirEntry(
+  Fts3Table *p,                   /* FTS3 table handle */
+  sqlite3_int64 iAbsLevel,        /* Absolute level to delete from */
+  int iIdx                        /* Index of %_segdir entry to delete */
+){
+  int rc;                         /* Return code */
+  sqlite3_stmt *pDelete = 0;      /* DELETE statement */
+
+  rc = fts3SqlStmt(p, SQL_DELETE_SEGDIR_ENTRY, &pDelete, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int64(pDelete, 1, iAbsLevel);
+    sqlite3_bind_int(pDelete, 2, iIdx);
+    sqlite3_step(pDelete);
+    rc = sqlite3_reset(pDelete);
+  }
+
+  return rc;
+}
+
+/*
+** One or more segments have just been removed from absolute level iAbsLevel.
+** Update the 'idx' values of the remaining segments in the level so that
+** the idx values are a contiguous sequence starting from 0.
+*/
+static int fts3RepackSegdirLevel(
+  Fts3Table *p,                   /* FTS3 table handle */
+  sqlite3_int64 iAbsLevel         /* Absolute level to repack */
+){
+  int rc;                         /* Return code */
+  int *aIdx = 0;                  /* Array of remaining idx values */
+  int nIdx = 0;                   /* Valid entries in aIdx[] */
+  int nAlloc = 0;                 /* Allocated size of aIdx[] */
+  int i;                          /* Iterator variable */
+  sqlite3_stmt *pSelect = 0;      /* Select statement to read idx values */
+  sqlite3_stmt *pUpdate = 0;      /* Update statement to modify idx values */
+
+  rc = fts3SqlStmt(p, SQL_SELECT_INDEXES, &pSelect, 0);
+  if( rc==SQLITE_OK ){
+    int rc2;
+    sqlite3_bind_int64(pSelect, 1, iAbsLevel);
+    while( SQLITE_ROW==sqlite3_step(pSelect) ){
+      if( nIdx>=nAlloc ){
+        int *aNew;
+        nAlloc += 16;
+        aNew = sqlite3_realloc(aIdx, nAlloc*sizeof(int));
+        if( !aNew ){
+          rc = SQLITE_NOMEM;
+          break;
+        }
+        aIdx = aNew;
+      }
+      aIdx[nIdx++] = sqlite3_column_int(pSelect, 0);
+    }
+    rc2 = sqlite3_reset(pSelect);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = fts3SqlStmt(p, SQL_SHIFT_SEGDIR_ENTRY, &pUpdate, 0);
+  }
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int64(pUpdate, 2, iAbsLevel);
+  }
+
+  assert( p->bIgnoreSavepoint==0 );
+  p->bIgnoreSavepoint = 1;
+  for(i=0; rc==SQLITE_OK && i<nIdx; i++){
+    if( aIdx[i]!=i ){
+      sqlite3_bind_int(pUpdate, 3, aIdx[i]);
+      sqlite3_bind_int(pUpdate, 1, i);
+      sqlite3_step(pUpdate);
+      rc = sqlite3_reset(pUpdate);
+    }
+  }
+  p->bIgnoreSavepoint = 0;
+
+  sqlite3_free(aIdx);
+  return rc;
+}
+
+static void fts3StartNode(Blob *pNode, int iHeight, sqlite3_int64 iChild){
+  pNode->a[0] = (char)iHeight;
+  if( iChild ){
+    assert( pNode->nAlloc>=1+sqlite3Fts3VarintLen(iChild) );
+    pNode->n = 1 + sqlite3Fts3PutVarint(&pNode->a[1], iChild);
+  }else{
+    assert( pNode->nAlloc>=1 );
+    pNode->n = 1;
+  }
+}
+
+/*
+** The first two arguments are a pointer to and the size of a segment b-tree
+** node. The node may be a leaf or an internal node.
+**
+** This function creates a new node image in blob object *pNew by copying
+** all terms that are greater than or equal to zTerm/nTerm (for leaf nodes)
+** or greater than zTerm/nTerm (for internal nodes) from aNode/nNode.
+*/
+static int fts3TruncateNode(
+  const char *aNode,              /* Current node image */
+  int nNode,                      /* Size of aNode in bytes */
+  Blob *pNew,                     /* OUT: Write new node image here */
+  const char *zTerm,              /* Omit all terms smaller than this */
+  int nTerm,                      /* Size of zTerm in bytes */
+  sqlite3_int64 *piBlock          /* OUT: Block number in next layer down */
+){
+  NodeReader reader;              /* Reader object */
+  Blob prev = {0, 0, 0};          /* Previous term written to new node */
+  int rc = SQLITE_OK;             /* Return code */
+  int bLeaf = aNode[0]=='\0';     /* True for a leaf node */
+
+  /* Allocate required output space */
+  blobGrowBuffer(pNew, nNode, &rc);
+  if( rc!=SQLITE_OK ) return rc;
+  pNew->n = 0;
+
+  /* Populate new node buffer */
+  for(rc = nodeReaderInit(&reader, aNode, nNode); 
+      rc==SQLITE_OK && reader.aNode; 
+      rc = nodeReaderNext(&reader)
+  ){
+    if( pNew->n==0 ){
+      int res = fts3TermCmp(reader.term.a, reader.term.n, zTerm, nTerm);
+      if( res<0 || (bLeaf==0 && res==0) ) continue;
+      fts3StartNode(pNew, (int)aNode[0], reader.iChild);
+      *piBlock = reader.iChild;
+    }
+    rc = fts3AppendToNode(
+        pNew, &prev, reader.term.a, reader.term.n,
+        reader.aDoclist, reader.nDoclist
+    );
+    if( rc!=SQLITE_OK ) break;
+  }
+  if( pNew->n==0 ){
+    fts3StartNode(pNew, (int)aNode[0], reader.iChild);
+    *piBlock = reader.iChild;
+  }
+  assert( pNew->n<=pNew->nAlloc );
+
+  nodeReaderRelease(&reader);
+  sqlite3_free(prev.a);
+  return rc;
+}
+
+/*
+** Remove all terms smaller than zTerm/nTerm from segment iIdx in absolute 
+** level iAbsLevel. This may involve deleting entries from the %_segments
+** table, and modifying existing entries in both the %_segments and %_segdir
+** tables.
+**
+** SQLITE_OK is returned if the segment is updated successfully. Or an
+** SQLite error code otherwise.
+*/
+static int fts3TruncateSegment(
+  Fts3Table *p,                   /* FTS3 table handle */
+  sqlite3_int64 iAbsLevel,        /* Absolute level of segment to modify */
+  int iIdx,                       /* Index within level of segment to modify */
+  const char *zTerm,              /* Remove terms smaller than this */
+  int nTerm                      /* Number of bytes in buffer zTerm */
+){
+  int rc = SQLITE_OK;             /* Return code */
+  Blob root = {0,0,0};            /* New root page image */
+  Blob block = {0,0,0};           /* Buffer used for any other block */
+  sqlite3_int64 iBlock = 0;       /* Block id */
+  sqlite3_int64 iNewStart = 0;    /* New value for iStartBlock */
+  sqlite3_int64 iOldStart = 0;    /* Old value for iStartBlock */
+  sqlite3_stmt *pFetch = 0;       /* Statement used to fetch segdir */
+
+  rc = fts3SqlStmt(p, SQL_SELECT_SEGDIR, &pFetch, 0);
+  if( rc==SQLITE_OK ){
+    int rc2;                      /* sqlite3_reset() return code */
+    sqlite3_bind_int64(pFetch, 1, iAbsLevel);
+    sqlite3_bind_int(pFetch, 2, iIdx);
+    if( SQLITE_ROW==sqlite3_step(pFetch) ){
+      const char *aRoot = sqlite3_column_blob(pFetch, 4);
+      int nRoot = sqlite3_column_bytes(pFetch, 4);
+      iOldStart = sqlite3_column_int64(pFetch, 1);
+      rc = fts3TruncateNode(aRoot, nRoot, &root, zTerm, nTerm, &iBlock);
+    }
+    rc2 = sqlite3_reset(pFetch);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }
+
+  while( rc==SQLITE_OK && iBlock ){
+    char *aBlock = 0;
+    int nBlock = 0;
+    iNewStart = iBlock;
+
+    rc = sqlite3Fts3ReadBlock(p, iBlock, &aBlock, &nBlock, 0);
+    if( rc==SQLITE_OK ){
+      rc = fts3TruncateNode(aBlock, nBlock, &block, zTerm, nTerm, &iBlock);
+    }
+    if( rc==SQLITE_OK ){
+      rc = fts3WriteSegment(p, iNewStart, block.a, block.n);
+    }
+    sqlite3_free(aBlock);
+  }
+
+  /* Variable iNewStart now contains the first valid leaf node. */
+  if( rc==SQLITE_OK && iNewStart ){
+    sqlite3_stmt *pDel = 0;
+    rc = fts3SqlStmt(p, SQL_DELETE_SEGMENTS_RANGE, &pDel, 0);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_int64(pDel, 1, iOldStart);
+      sqlite3_bind_int64(pDel, 2, iNewStart-1);
+      sqlite3_step(pDel);
+      rc = sqlite3_reset(pDel);
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    sqlite3_stmt *pChomp = 0;
+    rc = fts3SqlStmt(p, SQL_CHOMP_SEGDIR, &pChomp, 0);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_int64(pChomp, 1, iNewStart);
+      sqlite3_bind_blob(pChomp, 2, root.a, root.n, SQLITE_STATIC);
+      sqlite3_bind_int64(pChomp, 3, iAbsLevel);
+      sqlite3_bind_int(pChomp, 4, iIdx);
+      sqlite3_step(pChomp);
+      rc = sqlite3_reset(pChomp);
+    }
+  }
+
+  sqlite3_free(root.a);
+  sqlite3_free(block.a);
+  return rc;
+}
+
+/*
+** This function is called after an incrmental-merge operation has run to
+** merge (or partially merge) two or more segments from absolute level
+** iAbsLevel.
+**
+** Each input segment is either removed from the db completely (if all of
+** its data was copied to the output segment by the incrmerge operation)
+** or modified in place so that it no longer contains those entries that
+** have been duplicated in the output segment.
+*/
+static int fts3IncrmergeChomp(
+  Fts3Table *p,                   /* FTS table handle */
+  sqlite3_int64 iAbsLevel,        /* Absolute level containing segments */
+  Fts3MultiSegReader *pCsr,       /* Chomp all segments opened by this cursor */
+  int *pnRem                      /* Number of segments not deleted */
+){
+  int i;
+  int nRem = 0;
+  int rc = SQLITE_OK;
+
+  for(i=pCsr->nSegment-1; i>=0 && rc==SQLITE_OK; i--){
+    Fts3SegReader *pSeg = 0;
+    int j;
+
+    /* Find the Fts3SegReader object with Fts3SegReader.iIdx==i. It is hiding
+    ** somewhere in the pCsr->apSegment[] array.  */
+    for(j=0; ALWAYS(j<pCsr->nSegment); j++){
+      pSeg = pCsr->apSegment[j];
+      if( pSeg->iIdx==i ) break;
+    }
+    assert( j<pCsr->nSegment && pSeg->iIdx==i );
+
+    if( pSeg->aNode==0 ){
+      /* Seg-reader is at EOF. Remove the entire input segment. */
+      rc = fts3DeleteSegment(p, pSeg);
+      if( rc==SQLITE_OK ){
+        rc = fts3RemoveSegdirEntry(p, iAbsLevel, pSeg->iIdx);
+      }
+      *pnRem = 0;
+    }else{
+      /* The incremental merge did not copy all the data from this 
+      ** segment to the upper level. The segment is modified in place
+      ** so that it contains no keys smaller than zTerm/nTerm. */ 
+      const char *zTerm = pSeg->zTerm;
+      int nTerm = pSeg->nTerm;
+      rc = fts3TruncateSegment(p, iAbsLevel, pSeg->iIdx, zTerm, nTerm);
+      nRem++;
+    }
+  }
+
+  if( rc==SQLITE_OK && nRem!=pCsr->nSegment ){
+    rc = fts3RepackSegdirLevel(p, iAbsLevel);
+  }
+
+  *pnRem = nRem;
+  return rc;
+}
+
+/*
+** Store an incr-merge hint in the database.
+*/
+static int fts3IncrmergeHintStore(Fts3Table *p, Blob *pHint){
+  sqlite3_stmt *pReplace = 0;
+  int rc;                         /* Return code */
+
+  rc = fts3SqlStmt(p, SQL_REPLACE_STAT, &pReplace, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int(pReplace, 1, FTS_STAT_INCRMERGEHINT);
+    sqlite3_bind_blob(pReplace, 2, pHint->a, pHint->n, SQLITE_STATIC);
+    sqlite3_step(pReplace);
+    rc = sqlite3_reset(pReplace);
+  }
+
+  return rc;
+}
+
+/*
+** Load an incr-merge hint from the database. The incr-merge hint, if one 
+** exists, is stored in the rowid==1 row of the %_stat table.
+**
+** If successful, populate blob *pHint with the value read from the %_stat
+** table and return SQLITE_OK. Otherwise, if an error occurs, return an
+** SQLite error code.
+*/
+static int fts3IncrmergeHintLoad(Fts3Table *p, Blob *pHint){
+  sqlite3_stmt *pSelect = 0;
+  int rc;
+
+  pHint->n = 0;
+  rc = fts3SqlStmt(p, SQL_SELECT_STAT, &pSelect, 0);
+  if( rc==SQLITE_OK ){
+    int rc2;
+    sqlite3_bind_int(pSelect, 1, FTS_STAT_INCRMERGEHINT);
+    if( SQLITE_ROW==sqlite3_step(pSelect) ){
+      const char *aHint = sqlite3_column_blob(pSelect, 0);
+      int nHint = sqlite3_column_bytes(pSelect, 0);
+      if( aHint ){
+        blobGrowBuffer(pHint, nHint, &rc);
+        if( rc==SQLITE_OK ){
+          memcpy(pHint->a, aHint, nHint);
+          pHint->n = nHint;
+        }
+      }
+    }
+    rc2 = sqlite3_reset(pSelect);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }
+
+  return rc;
+}
+
+/*
+** If *pRc is not SQLITE_OK when this function is called, it is a no-op.
+** Otherwise, append an entry to the hint stored in blob *pHint. Each entry
+** consists of two varints, the absolute level number of the input segments 
+** and the number of input segments.
+**
+** If successful, leave *pRc set to SQLITE_OK and return. If an error occurs,
+** set *pRc to an SQLite error code before returning.
+*/
+static void fts3IncrmergeHintPush(
+  Blob *pHint,                    /* Hint blob to append to */
+  i64 iAbsLevel,                  /* First varint to store in hint */
+  int nInput,                     /* Second varint to store in hint */
+  int *pRc                        /* IN/OUT: Error code */
+){
+  blobGrowBuffer(pHint, pHint->n + 2*FTS3_VARINT_MAX, pRc);
+  if( *pRc==SQLITE_OK ){
+    pHint->n += sqlite3Fts3PutVarint(&pHint->a[pHint->n], iAbsLevel);
+    pHint->n += sqlite3Fts3PutVarint(&pHint->a[pHint->n], (i64)nInput);
+  }
+}
+
+/*
+** Read the last entry (most recently pushed) from the hint blob *pHint
+** and then remove the entry. Write the two values read to *piAbsLevel and 
+** *pnInput before returning.
+**
+** If no error occurs, return SQLITE_OK. If the hint blob in *pHint does
+** not contain at least two valid varints, return SQLITE_CORRUPT_VTAB.
+*/
+static int fts3IncrmergeHintPop(Blob *pHint, i64 *piAbsLevel, int *pnInput){
+  const int nHint = pHint->n;
+  int i;
+
+  i = pHint->n-2;
+  while( i>0 && (pHint->a[i-1] & 0x80) ) i--;
+  while( i>0 && (pHint->a[i-1] & 0x80) ) i--;
+
+  pHint->n = i;
+  i += sqlite3Fts3GetVarint(&pHint->a[i], piAbsLevel);
+  i += fts3GetVarint32(&pHint->a[i], pnInput);
+  if( i!=nHint ) return FTS_CORRUPT_VTAB;
+
+  return SQLITE_OK;
+}
+
+
+/*
+** Attempt an incremental merge that writes nMerge leaf blocks.
+**
+** Incremental merges happen nMin segments at a time. The segments 
+** to be merged are the nMin oldest segments (the ones with the smallest 
+** values for the _segdir.idx field) in the highest level that contains 
+** at least nMin segments. Multiple merges might occur in an attempt to 
+** write the quota of nMerge leaf blocks.
+*/
+SQLITE_PRIVATE int sqlite3Fts3Incrmerge(Fts3Table *p, int nMerge, int nMin){
+  int rc;                         /* Return code */
+  int nRem = nMerge;              /* Number of leaf pages yet to  be written */
+  Fts3MultiSegReader *pCsr;       /* Cursor used to read input data */
+  Fts3SegFilter *pFilter;         /* Filter used with cursor pCsr */
+  IncrmergeWriter *pWriter;       /* Writer object */
+  int nSeg = 0;                   /* Number of input segments */
+  sqlite3_int64 iAbsLevel = 0;    /* Absolute level number to work on */
+  Blob hint = {0, 0, 0};          /* Hint read from %_stat table */
+  int bDirtyHint = 0;             /* True if blob 'hint' has been modified */
+
+  /* Allocate space for the cursor, filter and writer objects */
+  const int nAlloc = sizeof(*pCsr) + sizeof(*pFilter) + sizeof(*pWriter);
+  pWriter = (IncrmergeWriter *)sqlite3_malloc(nAlloc);
+  if( !pWriter ) return SQLITE_NOMEM;
+  pFilter = (Fts3SegFilter *)&pWriter[1];
+  pCsr = (Fts3MultiSegReader *)&pFilter[1];
+
+  rc = fts3IncrmergeHintLoad(p, &hint);
+  while( rc==SQLITE_OK && nRem>0 ){
+    const i64 nMod = FTS3_SEGDIR_MAXLEVEL * p->nIndex;
+    sqlite3_stmt *pFindLevel = 0; /* SQL used to determine iAbsLevel */
+    int bUseHint = 0;             /* True if attempting to append */
+    int iIdx = 0;                 /* Largest idx in level (iAbsLevel+1) */
+
+    /* Search the %_segdir table for the absolute level with the smallest
+    ** relative level number that contains at least nMin segments, if any.
+    ** If one is found, set iAbsLevel to the absolute level number and
+    ** nSeg to nMin. If no level with at least nMin segments can be found, 
+    ** set nSeg to -1.
+    */
+    rc = fts3SqlStmt(p, SQL_FIND_MERGE_LEVEL, &pFindLevel, 0);
+    sqlite3_bind_int(pFindLevel, 1, MAX(2, nMin));
+    if( sqlite3_step(pFindLevel)==SQLITE_ROW ){
+      iAbsLevel = sqlite3_column_int64(pFindLevel, 0);
+      nSeg = sqlite3_column_int(pFindLevel, 1);
+      assert( nSeg>=2 );
+    }else{
+      nSeg = -1;
+    }
+    rc = sqlite3_reset(pFindLevel);
+
+    /* If the hint read from the %_stat table is not empty, check if the
+    ** last entry in it specifies a relative level smaller than or equal
+    ** to the level identified by the block above (if any). If so, this 
+    ** iteration of the loop will work on merging at the hinted level.
+    */
+    if( rc==SQLITE_OK && hint.n ){
+      int nHint = hint.n;
+      sqlite3_int64 iHintAbsLevel = 0;      /* Hint level */
+      int nHintSeg = 0;                     /* Hint number of segments */
+
+      rc = fts3IncrmergeHintPop(&hint, &iHintAbsLevel, &nHintSeg);
+      if( nSeg<0 || (iAbsLevel % nMod) >= (iHintAbsLevel % nMod) ){
+        iAbsLevel = iHintAbsLevel;
+        nSeg = nHintSeg;
+        bUseHint = 1;
+        bDirtyHint = 1;
+      }else{
+        /* This undoes the effect of the HintPop() above - so that no entry
+        ** is removed from the hint blob.  */
+        hint.n = nHint;
+      }
+    }
+
+    /* If nSeg is less that zero, then there is no level with at least
+    ** nMin segments and no hint in the %_stat table. No work to do.
+    ** Exit early in this case.  */
+    if( nSeg<0 ) break;
+
+    /* Open a cursor to iterate through the contents of the oldest nSeg 
+    ** indexes of absolute level iAbsLevel. If this cursor is opened using 
+    ** the 'hint' parameters, it is possible that there are less than nSeg
+    ** segments available in level iAbsLevel. In this case, no work is
+    ** done on iAbsLevel - fall through to the next iteration of the loop 
+    ** to start work on some other level.  */
+    memset(pWriter, 0, nAlloc);
+    pFilter->flags = FTS3_SEGMENT_REQUIRE_POS;
+
+    if( rc==SQLITE_OK ){
+      rc = fts3IncrmergeOutputIdx(p, iAbsLevel, &iIdx);
+      assert( bUseHint==1 || bUseHint==0 );
+      if( iIdx==0 || (bUseHint && iIdx==1) ){
+        int bIgnore = 0;
+        rc = fts3SegmentIsMaxLevel(p, iAbsLevel+1, &bIgnore);
+        if( bIgnore ){
+          pFilter->flags |= FTS3_SEGMENT_IGNORE_EMPTY;
+        }
+      }
+    }
+
+    if( rc==SQLITE_OK ){
+      rc = fts3IncrmergeCsr(p, iAbsLevel, nSeg, pCsr);
+    }
+    if( SQLITE_OK==rc && pCsr->nSegment==nSeg
+     && SQLITE_OK==(rc = sqlite3Fts3SegReaderStart(p, pCsr, pFilter))
+     && SQLITE_ROW==(rc = sqlite3Fts3SegReaderStep(p, pCsr))
+    ){
+      if( bUseHint && iIdx>0 ){
+        const char *zKey = pCsr->zTerm;
+        int nKey = pCsr->nTerm;
+        rc = fts3IncrmergeLoad(p, iAbsLevel, iIdx-1, zKey, nKey, pWriter);
+      }else{
+        rc = fts3IncrmergeWriter(p, iAbsLevel, iIdx, pCsr, pWriter);
+      }
+
+      if( rc==SQLITE_OK && pWriter->nLeafEst ){
+        fts3LogMerge(nSeg, iAbsLevel);
+        do {
+          rc = fts3IncrmergeAppend(p, pWriter, pCsr);
+          if( rc==SQLITE_OK ) rc = sqlite3Fts3SegReaderStep(p, pCsr);
+          if( pWriter->nWork>=nRem && rc==SQLITE_ROW ) rc = SQLITE_OK;
+        }while( rc==SQLITE_ROW );
+
+        /* Update or delete the input segments */
+        if( rc==SQLITE_OK ){
+          nRem -= (1 + pWriter->nWork);
+          rc = fts3IncrmergeChomp(p, iAbsLevel, pCsr, &nSeg);
+          if( nSeg!=0 ){
+            bDirtyHint = 1;
+            fts3IncrmergeHintPush(&hint, iAbsLevel, nSeg, &rc);
+          }
+        }
+      }
+
+      if( nSeg!=0 ){
+        pWriter->nLeafData = pWriter->nLeafData * -1;
+      }
+      fts3IncrmergeRelease(p, pWriter, &rc);
+      if( nSeg==0 && pWriter->bNoLeafData==0 ){
+        fts3PromoteSegments(p, iAbsLevel+1, pWriter->nLeafData);
+      }
+    }
+
+    sqlite3Fts3SegReaderFinish(pCsr);
+  }
+
+  /* Write the hint values into the %_stat table for the next incr-merger */
+  if( bDirtyHint && rc==SQLITE_OK ){
+    rc = fts3IncrmergeHintStore(p, &hint);
+  }
+
+  sqlite3_free(pWriter);
+  sqlite3_free(hint.a);
+  return rc;
+}
+
+/*
+** Convert the text beginning at *pz into an integer and return
+** its value.  Advance *pz to point to the first character past
+** the integer.
+*/
+static int fts3Getint(const char **pz){
+  const char *z = *pz;
+  int i = 0;
+  while( (*z)>='0' && (*z)<='9' ) i = 10*i + *(z++) - '0';
+  *pz = z;
+  return i;
+}
+
+/*
+** Process statements of the form:
+**
+**    INSERT INTO table(table) VALUES('merge=A,B');
+**
+** A and B are integers that decode to be the number of leaf pages
+** written for the merge, and the minimum number of segments on a level
+** before it will be selected for a merge, respectively.
+*/
+static int fts3DoIncrmerge(
+  Fts3Table *p,                   /* FTS3 table handle */
+  const char *zParam              /* Nul-terminated string containing "A,B" */
+){
+  int rc;
+  int nMin = (FTS3_MERGE_COUNT / 2);
+  int nMerge = 0;
+  const char *z = zParam;
+
+  /* Read the first integer value */
+  nMerge = fts3Getint(&z);
+
+  /* If the first integer value is followed by a ',',  read the second
+  ** integer value. */
+  if( z[0]==',' && z[1]!='\0' ){
+    z++;
+    nMin = fts3Getint(&z);
+  }
+
+  if( z[0]!='\0' || nMin<2 ){
+    rc = SQLITE_ERROR;
+  }else{
+    rc = SQLITE_OK;
+    if( !p->bHasStat ){
+      assert( p->bFts4==0 );
+      sqlite3Fts3CreateStatTable(&rc, p);
+    }
+    if( rc==SQLITE_OK ){
+      rc = sqlite3Fts3Incrmerge(p, nMerge, nMin);
+    }
+    sqlite3Fts3SegmentsClose(p);
+  }
+  return rc;
+}
+
+/*
+** Process statements of the form:
+**
+**    INSERT INTO table(table) VALUES('automerge=X');
+**
+** where X is an integer.  X==0 means to turn automerge off.  X!=0 means
+** turn it on.  The setting is persistent.
+*/
+static int fts3DoAutoincrmerge(
+  Fts3Table *p,                   /* FTS3 table handle */
+  const char *zParam              /* Nul-terminated string containing boolean */
+){
+  int rc = SQLITE_OK;
+  sqlite3_stmt *pStmt = 0;
+  p->nAutoincrmerge = fts3Getint(&zParam);
+  if( p->nAutoincrmerge==1 || p->nAutoincrmerge>FTS3_MERGE_COUNT ){
+    p->nAutoincrmerge = 8;
+  }
+  if( !p->bHasStat ){
+    assert( p->bFts4==0 );
+    sqlite3Fts3CreateStatTable(&rc, p);
+    if( rc ) return rc;
+  }
+  rc = fts3SqlStmt(p, SQL_REPLACE_STAT, &pStmt, 0);
+  if( rc ) return rc;
+  sqlite3_bind_int(pStmt, 1, FTS_STAT_AUTOINCRMERGE);
+  sqlite3_bind_int(pStmt, 2, p->nAutoincrmerge);
+  sqlite3_step(pStmt);
+  rc = sqlite3_reset(pStmt);
+  return rc;
+}
+
+/*
+** Return a 64-bit checksum for the FTS index entry specified by the
+** arguments to this function.
+*/
+static u64 fts3ChecksumEntry(
+  const char *zTerm,              /* Pointer to buffer containing term */
+  int nTerm,                      /* Size of zTerm in bytes */
+  int iLangid,                    /* Language id for current row */
+  int iIndex,                     /* Index (0..Fts3Table.nIndex-1) */
+  i64 iDocid,                     /* Docid for current row. */
+  int iCol,                       /* Column number */
+  int iPos                        /* Position */
+){
+  int i;
+  u64 ret = (u64)iDocid;
+
+  ret += (ret<<3) + iLangid;
+  ret += (ret<<3) + iIndex;
+  ret += (ret<<3) + iCol;
+  ret += (ret<<3) + iPos;
+  for(i=0; i<nTerm; i++) ret += (ret<<3) + zTerm[i];
+
+  return ret;
+}
+
+/*
+** Return a checksum of all entries in the FTS index that correspond to
+** language id iLangid. The checksum is calculated by XORing the checksums
+** of each individual entry (see fts3ChecksumEntry()) together.
+**
+** If successful, the checksum value is returned and *pRc set to SQLITE_OK.
+** Otherwise, if an error occurs, *pRc is set to an SQLite error code. The
+** return value is undefined in this case.
+*/
+static u64 fts3ChecksumIndex(
+  Fts3Table *p,                   /* FTS3 table handle */
+  int iLangid,                    /* Language id to return cksum for */
+  int iIndex,                     /* Index to cksum (0..p->nIndex-1) */
+  int *pRc                        /* OUT: Return code */
+){
+  Fts3SegFilter filter;
+  Fts3MultiSegReader csr;
+  int rc;
+  u64 cksum = 0;
+
+  assert( *pRc==SQLITE_OK );
+
+  memset(&filter, 0, sizeof(filter));
+  memset(&csr, 0, sizeof(csr));
+  filter.flags =  FTS3_SEGMENT_REQUIRE_POS|FTS3_SEGMENT_IGNORE_EMPTY;
+  filter.flags |= FTS3_SEGMENT_SCAN;
+
+  rc = sqlite3Fts3SegReaderCursor(
+      p, iLangid, iIndex, FTS3_SEGCURSOR_ALL, 0, 0, 0, 1,&csr
+  );
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts3SegReaderStart(p, &csr, &filter);
+  }
+
+  if( rc==SQLITE_OK ){
+    while( SQLITE_ROW==(rc = sqlite3Fts3SegReaderStep(p, &csr)) ){
+      char *pCsr = csr.aDoclist;
+      char *pEnd = &pCsr[csr.nDoclist];
+
+      i64 iDocid = 0;
+      i64 iCol = 0;
+      i64 iPos = 0;
+
+      pCsr += sqlite3Fts3GetVarint(pCsr, &iDocid);
+      while( pCsr<pEnd ){
+        i64 iVal = 0;
+        pCsr += sqlite3Fts3GetVarint(pCsr, &iVal);
+        if( pCsr<pEnd ){
+          if( iVal==0 || iVal==1 ){
+            iCol = 0;
+            iPos = 0;
+            if( iVal ){
+              pCsr += sqlite3Fts3GetVarint(pCsr, &iCol);
+            }else{
+              pCsr += sqlite3Fts3GetVarint(pCsr, &iVal);
+              iDocid += iVal;
+            }
+          }else{
+            iPos += (iVal - 2);
+            cksum = cksum ^ fts3ChecksumEntry(
+                csr.zTerm, csr.nTerm, iLangid, iIndex, iDocid,
+                (int)iCol, (int)iPos
+            );
+          }
+        }
+      }
+    }
+  }
+  sqlite3Fts3SegReaderFinish(&csr);
+
+  *pRc = rc;
+  return cksum;
+}
+
+/*
+** Check if the contents of the FTS index match the current contents of the
+** content table. If no error occurs and the contents do match, set *pbOk
+** to true and return SQLITE_OK. Or if the contents do not match, set *pbOk
+** to false before returning.
+**
+** If an error occurs (e.g. an OOM or IO error), return an SQLite error 
+** code. The final value of *pbOk is undefined in this case.
+*/
+static int fts3IntegrityCheck(Fts3Table *p, int *pbOk){
+  int rc = SQLITE_OK;             /* Return code */
+  u64 cksum1 = 0;                 /* Checksum based on FTS index contents */
+  u64 cksum2 = 0;                 /* Checksum based on %_content contents */
+  sqlite3_stmt *pAllLangid = 0;   /* Statement to return all language-ids */
+
+  /* This block calculates the checksum according to the FTS index. */
+  rc = fts3SqlStmt(p, SQL_SELECT_ALL_LANGID, &pAllLangid, 0);
+  if( rc==SQLITE_OK ){
+    int rc2;
+    sqlite3_bind_int(pAllLangid, 1, p->iPrevLangid);
+    sqlite3_bind_int(pAllLangid, 2, p->nIndex);
+    while( rc==SQLITE_OK && sqlite3_step(pAllLangid)==SQLITE_ROW ){
+      int iLangid = sqlite3_column_int(pAllLangid, 0);
+      int i;
+      for(i=0; i<p->nIndex; i++){
+        cksum1 = cksum1 ^ fts3ChecksumIndex(p, iLangid, i, &rc);
+      }
+    }
+    rc2 = sqlite3_reset(pAllLangid);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }
+
+  /* This block calculates the checksum according to the %_content table */
+  if( rc==SQLITE_OK ){
+    sqlite3_tokenizer_module const *pModule = p->pTokenizer->pModule;
+    sqlite3_stmt *pStmt = 0;
+    char *zSql;
+   
+    zSql = sqlite3_mprintf("SELECT %s" , p->zReadExprlist);
+    if( !zSql ){
+      rc = SQLITE_NOMEM;
+    }else{
+      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pStmt, 0);
+      sqlite3_free(zSql);
+    }
+
+    while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
+      i64 iDocid = sqlite3_column_int64(pStmt, 0);
+      int iLang = langidFromSelect(p, pStmt);
+      int iCol;
+
+      for(iCol=0; rc==SQLITE_OK && iCol<p->nColumn; iCol++){
+        if( p->abNotindexed[iCol]==0 ){
+          const char *zText = (const char *)sqlite3_column_text(pStmt, iCol+1);
+          int nText = sqlite3_column_bytes(pStmt, iCol+1);
+          sqlite3_tokenizer_cursor *pT = 0;
+
+          rc = sqlite3Fts3OpenTokenizer(p->pTokenizer, iLang, zText, nText,&pT);
+          while( rc==SQLITE_OK ){
+            char const *zToken;       /* Buffer containing token */
+            int nToken = 0;           /* Number of bytes in token */
+            int iDum1 = 0, iDum2 = 0; /* Dummy variables */
+            int iPos = 0;             /* Position of token in zText */
+
+            rc = pModule->xNext(pT, &zToken, &nToken, &iDum1, &iDum2, &iPos);
+            if( rc==SQLITE_OK ){
+              int i;
+              cksum2 = cksum2 ^ fts3ChecksumEntry(
+                  zToken, nToken, iLang, 0, iDocid, iCol, iPos
+              );
+              for(i=1; i<p->nIndex; i++){
+                if( p->aIndex[i].nPrefix<=nToken ){
+                  cksum2 = cksum2 ^ fts3ChecksumEntry(
+                      zToken, p->aIndex[i].nPrefix, iLang, i, iDocid, iCol, iPos
+                  );
+                }
+              }
+            }
+          }
+          if( pT ) pModule->xClose(pT);
+          if( rc==SQLITE_DONE ) rc = SQLITE_OK;
+        }
+      }
+    }
+
+    sqlite3_finalize(pStmt);
+  }
+
+  *pbOk = (cksum1==cksum2);
+  return rc;
+}
+
+/*
+** Run the integrity-check. If no error occurs and the current contents of
+** the FTS index are correct, return SQLITE_OK. Or, if the contents of the
+** FTS index are incorrect, return SQLITE_CORRUPT_VTAB.
+**
+** Or, if an error (e.g. an OOM or IO error) occurs, return an SQLite 
+** error code.
+**
+** The integrity-check works as follows. For each token and indexed token
+** prefix in the document set, a 64-bit checksum is calculated (by code
+** in fts3ChecksumEntry()) based on the following:
+**
+**     + The index number (0 for the main index, 1 for the first prefix
+**       index etc.),
+**     + The token (or token prefix) text itself, 
+**     + The language-id of the row it appears in,
+**     + The docid of the row it appears in,
+**     + The column it appears in, and
+**     + The tokens position within that column.
+**
+** The checksums for all entries in the index are XORed together to create
+** a single checksum for the entire index.
+**
+** The integrity-check code calculates the same checksum in two ways:
+**
+**     1. By scanning the contents of the FTS index, and 
+**     2. By scanning and tokenizing the content table.
+**
+** If the two checksums are identical, the integrity-check is deemed to have
+** passed.
+*/
+static int fts3DoIntegrityCheck(
+  Fts3Table *p                    /* FTS3 table handle */
+){
+  int rc;
+  int bOk = 0;
+  rc = fts3IntegrityCheck(p, &bOk);
+  if( rc==SQLITE_OK && bOk==0 ) rc = FTS_CORRUPT_VTAB;
+  return rc;
+}
+
+/*
+** Handle a 'special' INSERT of the form:
+**
+**   "INSERT INTO tbl(tbl) VALUES(<expr>)"
+**
+** Argument pVal contains the result of <expr>. Currently the only 
+** meaningful value to insert is the text 'optimize'.
+*/
+static int fts3SpecialInsert(Fts3Table *p, sqlite3_value *pVal){
+  int rc;                         /* Return Code */
+  const char *zVal = (const char *)sqlite3_value_text(pVal);
+  int nVal = sqlite3_value_bytes(pVal);
+
+  if( !zVal ){
+    return SQLITE_NOMEM;
+  }else if( nVal==8 && 0==sqlite3_strnicmp(zVal, "optimize", 8) ){
+    rc = fts3DoOptimize(p, 0);
+  }else if( nVal==7 && 0==sqlite3_strnicmp(zVal, "rebuild", 7) ){
+    rc = fts3DoRebuild(p);
+  }else if( nVal==15 && 0==sqlite3_strnicmp(zVal, "integrity-check", 15) ){
+    rc = fts3DoIntegrityCheck(p);
+  }else if( nVal>6 && 0==sqlite3_strnicmp(zVal, "merge=", 6) ){
+    rc = fts3DoIncrmerge(p, &zVal[6]);
+  }else if( nVal>10 && 0==sqlite3_strnicmp(zVal, "automerge=", 10) ){
+    rc = fts3DoAutoincrmerge(p, &zVal[10]);
+#ifdef SQLITE_TEST
+  }else if( nVal>9 && 0==sqlite3_strnicmp(zVal, "nodesize=", 9) ){
+    p->nNodeSize = atoi(&zVal[9]);
+    rc = SQLITE_OK;
+  }else if( nVal>11 && 0==sqlite3_strnicmp(zVal, "maxpending=", 9) ){
+    p->nMaxPendingData = atoi(&zVal[11]);
+    rc = SQLITE_OK;
+  }else if( nVal>21 && 0==sqlite3_strnicmp(zVal, "test-no-incr-doclist=", 21) ){
+    p->bNoIncrDoclist = atoi(&zVal[21]);
+    rc = SQLITE_OK;
+#endif
+  }else{
+    rc = SQLITE_ERROR;
+  }
+
+  return rc;
+}
+
+#ifndef SQLITE_DISABLE_FTS4_DEFERRED
+/*
+** Delete all cached deferred doclists. Deferred doclists are cached
+** (allocated) by the sqlite3Fts3CacheDeferredDoclists() function.
+*/
+SQLITE_PRIVATE void sqlite3Fts3FreeDeferredDoclists(Fts3Cursor *pCsr){
+  Fts3DeferredToken *pDef;
+  for(pDef=pCsr->pDeferred; pDef; pDef=pDef->pNext){
+    fts3PendingListDelete(pDef->pList);
+    pDef->pList = 0;
+  }
+}
+
+/*
+** Free all entries in the pCsr->pDeffered list. Entries are added to 
+** this list using sqlite3Fts3DeferToken().
+*/
+SQLITE_PRIVATE void sqlite3Fts3FreeDeferredTokens(Fts3Cursor *pCsr){
+  Fts3DeferredToken *pDef;
+  Fts3DeferredToken *pNext;
+  for(pDef=pCsr->pDeferred; pDef; pDef=pNext){
+    pNext = pDef->pNext;
+    fts3PendingListDelete(pDef->pList);
+    sqlite3_free(pDef);
+  }
+  pCsr->pDeferred = 0;
+}
+
+/*
+** Generate deferred-doclists for all tokens in the pCsr->pDeferred list
+** based on the row that pCsr currently points to.
+**
+** A deferred-doclist is like any other doclist with position information
+** included, except that it only contains entries for a single row of the
+** table, not for all rows.
+*/
+SQLITE_PRIVATE int sqlite3Fts3CacheDeferredDoclists(Fts3Cursor *pCsr){
+  int rc = SQLITE_OK;             /* Return code */
+  if( pCsr->pDeferred ){
+    int i;                        /* Used to iterate through table columns */
+    sqlite3_int64 iDocid;         /* Docid of the row pCsr points to */
+    Fts3DeferredToken *pDef;      /* Used to iterate through deferred tokens */
+  
+    Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
+    sqlite3_tokenizer *pT = p->pTokenizer;
+    sqlite3_tokenizer_module const *pModule = pT->pModule;
+   
+    assert( pCsr->isRequireSeek==0 );
+    iDocid = sqlite3_column_int64(pCsr->pStmt, 0);
+  
+    for(i=0; i<p->nColumn && rc==SQLITE_OK; i++){
+      if( p->abNotindexed[i]==0 ){
+        const char *zText = (const char *)sqlite3_column_text(pCsr->pStmt, i+1);
+        sqlite3_tokenizer_cursor *pTC = 0;
+
+        rc = sqlite3Fts3OpenTokenizer(pT, pCsr->iLangid, zText, -1, &pTC);
+        while( rc==SQLITE_OK ){
+          char const *zToken;       /* Buffer containing token */
+          int nToken = 0;           /* Number of bytes in token */
+          int iDum1 = 0, iDum2 = 0; /* Dummy variables */
+          int iPos = 0;             /* Position of token in zText */
+
+          rc = pModule->xNext(pTC, &zToken, &nToken, &iDum1, &iDum2, &iPos);
+          for(pDef=pCsr->pDeferred; pDef && rc==SQLITE_OK; pDef=pDef->pNext){
+            Fts3PhraseToken *pPT = pDef->pToken;
+            if( (pDef->iCol>=p->nColumn || pDef->iCol==i)
+                && (pPT->bFirst==0 || iPos==0)
+                && (pPT->n==nToken || (pPT->isPrefix && pPT->n<nToken))
+                && (0==memcmp(zToken, pPT->z, pPT->n))
+              ){
+              fts3PendingListAppend(&pDef->pList, iDocid, i, iPos, &rc);
+            }
+          }
+        }
+        if( pTC ) pModule->xClose(pTC);
+        if( rc==SQLITE_DONE ) rc = SQLITE_OK;
+      }
+    }
+
+    for(pDef=pCsr->pDeferred; pDef && rc==SQLITE_OK; pDef=pDef->pNext){
+      if( pDef->pList ){
+        rc = fts3PendingListAppendVarint(&pDef->pList, 0);
+      }
+    }
+  }
+
+  return rc;
+}
+
+SQLITE_PRIVATE int sqlite3Fts3DeferredTokenList(
+  Fts3DeferredToken *p, 
+  char **ppData, 
+  int *pnData
+){
+  char *pRet;
+  int nSkip;
+  sqlite3_int64 dummy;
+
+  *ppData = 0;
+  *pnData = 0;
+
+  if( p->pList==0 ){
+    return SQLITE_OK;
+  }
+
+  pRet = (char *)sqlite3_malloc(p->pList->nData);
+  if( !pRet ) return SQLITE_NOMEM;
+
+  nSkip = sqlite3Fts3GetVarint(p->pList->aData, &dummy);
+  *pnData = p->pList->nData - nSkip;
+  *ppData = pRet;
+  
+  memcpy(pRet, &p->pList->aData[nSkip], *pnData);
+  return SQLITE_OK;
+}
+
+/*
+** Add an entry for token pToken to the pCsr->pDeferred list.
+*/
+SQLITE_PRIVATE int sqlite3Fts3DeferToken(
+  Fts3Cursor *pCsr,               /* Fts3 table cursor */
+  Fts3PhraseToken *pToken,        /* Token to defer */
+  int iCol                        /* Column that token must appear in (or -1) */
+){
+  Fts3DeferredToken *pDeferred;
+  pDeferred = sqlite3_malloc(sizeof(*pDeferred));
+  if( !pDeferred ){
+    return SQLITE_NOMEM;
+  }
+  memset(pDeferred, 0, sizeof(*pDeferred));
+  pDeferred->pToken = pToken;
+  pDeferred->pNext = pCsr->pDeferred; 
+  pDeferred->iCol = iCol;
+  pCsr->pDeferred = pDeferred;
+
+  assert( pToken->pDeferred==0 );
+  pToken->pDeferred = pDeferred;
+
+  return SQLITE_OK;
+}
+#endif
+
+/*
+** SQLite value pRowid contains the rowid of a row that may or may not be
+** present in the FTS3 table. If it is, delete it and adjust the contents
+** of subsiduary data structures accordingly.
+*/
+static int fts3DeleteByRowid(
+  Fts3Table *p, 
+  sqlite3_value *pRowid, 
+  int *pnChng,                    /* IN/OUT: Decrement if row is deleted */
+  u32 *aSzDel
+){
+  int rc = SQLITE_OK;             /* Return code */
+  int bFound = 0;                 /* True if *pRowid really is in the table */
+
+  fts3DeleteTerms(&rc, p, pRowid, aSzDel, &bFound);
+  if( bFound && rc==SQLITE_OK ){
+    int isEmpty = 0;              /* Deleting *pRowid leaves the table empty */
+    rc = fts3IsEmpty(p, pRowid, &isEmpty);
+    if( rc==SQLITE_OK ){
+      if( isEmpty ){
+        /* Deleting this row means the whole table is empty. In this case
+        ** delete the contents of all three tables and throw away any
+        ** data in the pendingTerms hash table.  */
+        rc = fts3DeleteAll(p, 1);
+        *pnChng = 0;
+        memset(aSzDel, 0, sizeof(u32) * (p->nColumn+1) * 2);
+      }else{
+        *pnChng = *pnChng - 1;
+        if( p->zContentTbl==0 ){
+          fts3SqlExec(&rc, p, SQL_DELETE_CONTENT, &pRowid);
+        }
+        if( p->bHasDocsize ){
+          fts3SqlExec(&rc, p, SQL_DELETE_DOCSIZE, &pRowid);
+        }
+      }
+    }
+  }
+
+  return rc;
+}
+
+/*
+** This function does the work for the xUpdate method of FTS3 virtual
+** tables. The schema of the virtual table being:
+**
+**     CREATE TABLE <table name>( 
+**       <user columns>,
+**       <table name> HIDDEN, 
+**       docid HIDDEN, 
+**       <langid> HIDDEN
+**     );
+**
+** 
+*/
+SQLITE_PRIVATE int sqlite3Fts3UpdateMethod(
+  sqlite3_vtab *pVtab,            /* FTS3 vtab object */
+  int nArg,                       /* Size of argument array */
+  sqlite3_value **apVal,          /* Array of arguments */
+  sqlite_int64 *pRowid            /* OUT: The affected (or effected) rowid */
+){
+  Fts3Table *p = (Fts3Table *)pVtab;
+  int rc = SQLITE_OK;             /* Return Code */
+  int isRemove = 0;               /* True for an UPDATE or DELETE */
+  u32 *aSzIns = 0;                /* Sizes of inserted documents */
+  u32 *aSzDel = 0;                /* Sizes of deleted documents */
+  int nChng = 0;                  /* Net change in number of documents */
+  int bInsertDone = 0;
+
+  /* At this point it must be known if the %_stat table exists or not.
+  ** So bHasStat may not be 2.  */
+  assert( p->bHasStat==0 || p->bHasStat==1 );
+
+  assert( p->pSegments==0 );
+  assert( 
+      nArg==1                     /* DELETE operations */
+   || nArg==(2 + p->nColumn + 3)  /* INSERT or UPDATE operations */
+  );
+
+  /* Check for a "special" INSERT operation. One of the form:
+  **
+  **   INSERT INTO xyz(xyz) VALUES('command');
+  */
+  if( nArg>1 
+   && sqlite3_value_type(apVal[0])==SQLITE_NULL 
+   && sqlite3_value_type(apVal[p->nColumn+2])!=SQLITE_NULL 
+  ){
+    rc = fts3SpecialInsert(p, apVal[p->nColumn+2]);
+    goto update_out;
+  }
+
+  if( nArg>1 && sqlite3_value_int(apVal[2 + p->nColumn + 2])<0 ){
+    rc = SQLITE_CONSTRAINT;
+    goto update_out;
+  }
+
+  /* Allocate space to hold the change in document sizes */
+  aSzDel = sqlite3_malloc( sizeof(aSzDel[0])*(p->nColumn+1)*2 );
+  if( aSzDel==0 ){
+    rc = SQLITE_NOMEM;
+    goto update_out;
+  }
+  aSzIns = &aSzDel[p->nColumn+1];
+  memset(aSzDel, 0, sizeof(aSzDel[0])*(p->nColumn+1)*2);
+
+  rc = fts3Writelock(p);
+  if( rc!=SQLITE_OK ) goto update_out;
+
+  /* If this is an INSERT operation, or an UPDATE that modifies the rowid
+  ** value, then this operation requires constraint handling.
+  **
+  ** If the on-conflict mode is REPLACE, this means that the existing row
+  ** should be deleted from the database before inserting the new row. Or,
+  ** if the on-conflict mode is other than REPLACE, then this method must
+  ** detect the conflict and return SQLITE_CONSTRAINT before beginning to
+  ** modify the database file.
+  */
+  if( nArg>1 && p->zContentTbl==0 ){
+    /* Find the value object that holds the new rowid value. */
+    sqlite3_value *pNewRowid = apVal[3+p->nColumn];
+    if( sqlite3_value_type(pNewRowid)==SQLITE_NULL ){
+      pNewRowid = apVal[1];
+    }
+
+    if( sqlite3_value_type(pNewRowid)!=SQLITE_NULL && ( 
+        sqlite3_value_type(apVal[0])==SQLITE_NULL
+     || sqlite3_value_int64(apVal[0])!=sqlite3_value_int64(pNewRowid)
+    )){
+      /* The new rowid is not NULL (in this case the rowid will be
+      ** automatically assigned and there is no chance of a conflict), and 
+      ** the statement is either an INSERT or an UPDATE that modifies the
+      ** rowid column. So if the conflict mode is REPLACE, then delete any
+      ** existing row with rowid=pNewRowid. 
+      **
+      ** Or, if the conflict mode is not REPLACE, insert the new record into 
+      ** the %_content table. If we hit the duplicate rowid constraint (or any
+      ** other error) while doing so, return immediately.
+      **
+      ** This branch may also run if pNewRowid contains a value that cannot
+      ** be losslessly converted to an integer. In this case, the eventual 
+      ** call to fts3InsertData() (either just below or further on in this
+      ** function) will return SQLITE_MISMATCH. If fts3DeleteByRowid is 
+      ** invoked, it will delete zero rows (since no row will have
+      ** docid=$pNewRowid if $pNewRowid is not an integer value).
+      */
+      if( sqlite3_vtab_on_conflict(p->db)==SQLITE_REPLACE ){
+        rc = fts3DeleteByRowid(p, pNewRowid, &nChng, aSzDel);
+      }else{
+        rc = fts3InsertData(p, apVal, pRowid);
+        bInsertDone = 1;
+      }
+    }
+  }
+  if( rc!=SQLITE_OK ){
+    goto update_out;
+  }
+
+  /* If this is a DELETE or UPDATE operation, remove the old record. */
+  if( sqlite3_value_type(apVal[0])!=SQLITE_NULL ){
+    assert( sqlite3_value_type(apVal[0])==SQLITE_INTEGER );
+    rc = fts3DeleteByRowid(p, apVal[0], &nChng, aSzDel);
+    isRemove = 1;
+  }
+  
+  /* If this is an INSERT or UPDATE operation, insert the new record. */
+  if( nArg>1 && rc==SQLITE_OK ){
+    int iLangid = sqlite3_value_int(apVal[2 + p->nColumn + 2]);
+    if( bInsertDone==0 ){
+      rc = fts3InsertData(p, apVal, pRowid);
+      if( rc==SQLITE_CONSTRAINT && p->zContentTbl==0 ){
+        rc = FTS_CORRUPT_VTAB;
+      }
+    }
+    if( rc==SQLITE_OK && (!isRemove || *pRowid!=p->iPrevDocid ) ){
+      rc = fts3PendingTermsDocid(p, 0, iLangid, *pRowid);
+    }
+    if( rc==SQLITE_OK ){
+      assert( p->iPrevDocid==*pRowid );
+      rc = fts3InsertTerms(p, iLangid, apVal, aSzIns);
+    }
+    if( p->bHasDocsize ){
+      fts3InsertDocsize(&rc, p, aSzIns);
+    }
+    nChng++;
+  }
+
+  if( p->bFts4 ){
+    fts3UpdateDocTotals(&rc, p, aSzIns, aSzDel, nChng);
+  }
+
+ update_out:
+  sqlite3_free(aSzDel);
+  sqlite3Fts3SegmentsClose(p);
+  return rc;
+}
+
+/* 
+** Flush any data in the pending-terms hash table to disk. If successful,
+** merge all segments in the database (including the new segment, if 
+** there was any data to flush) into a single segment. 
+*/
+SQLITE_PRIVATE int sqlite3Fts3Optimize(Fts3Table *p){
+  int rc;
+  rc = sqlite3_exec(p->db, "SAVEPOINT fts3", 0, 0, 0);
+  if( rc==SQLITE_OK ){
+    rc = fts3DoOptimize(p, 1);
+    if( rc==SQLITE_OK || rc==SQLITE_DONE ){
+      int rc2 = sqlite3_exec(p->db, "RELEASE fts3", 0, 0, 0);
+      if( rc2!=SQLITE_OK ) rc = rc2;
+    }else{
+      sqlite3_exec(p->db, "ROLLBACK TO fts3", 0, 0, 0);
+      sqlite3_exec(p->db, "RELEASE fts3", 0, 0, 0);
+    }
+  }
+  sqlite3Fts3SegmentsClose(p);
+  return rc;
+}
+
+#endif
+
+/************** End of fts3_write.c ******************************************/
+/************** Begin file fts3_snippet.c ************************************/
+/*
+** 2009 Oct 23
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+*/
+
+/* #include "fts3Int.h" */
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
+
+/* #include <string.h> */
+/* #include <assert.h> */
+
+/*
+** Characters that may appear in the second argument to matchinfo().
+*/
+#define FTS3_MATCHINFO_NPHRASE   'p'        /* 1 value */
+#define FTS3_MATCHINFO_NCOL      'c'        /* 1 value */
+#define FTS3_MATCHINFO_NDOC      'n'        /* 1 value */
+#define FTS3_MATCHINFO_AVGLENGTH 'a'        /* nCol values */
+#define FTS3_MATCHINFO_LENGTH    'l'        /* nCol values */
+#define FTS3_MATCHINFO_LCS       's'        /* nCol values */
+#define FTS3_MATCHINFO_HITS      'x'        /* 3*nCol*nPhrase values */
+#define FTS3_MATCHINFO_LHITS     'y'        /* nCol*nPhrase values */
+#define FTS3_MATCHINFO_LHITS_BM  'b'        /* nCol*nPhrase values */
+
+/*
+** The default value for the second argument to matchinfo(). 
+*/
+#define FTS3_MATCHINFO_DEFAULT   "pcx"
+
+
+/*
+** Used as an fts3ExprIterate() context when loading phrase doclists to
+** Fts3Expr.aDoclist[]/nDoclist.
+*/
+typedef struct LoadDoclistCtx LoadDoclistCtx;
+struct LoadDoclistCtx {
+  Fts3Cursor *pCsr;               /* FTS3 Cursor */
+  int nPhrase;                    /* Number of phrases seen so far */
+  int nToken;                     /* Number of tokens seen so far */
+};
+
+/*
+** The following types are used as part of the implementation of the 
+** fts3BestSnippet() routine.
+*/
+typedef struct SnippetIter SnippetIter;
+typedef struct SnippetPhrase SnippetPhrase;
+typedef struct SnippetFragment SnippetFragment;
+
+struct SnippetIter {
+  Fts3Cursor *pCsr;               /* Cursor snippet is being generated from */
+  int iCol;                       /* Extract snippet from this column */
+  int nSnippet;                   /* Requested snippet length (in tokens) */
+  int nPhrase;                    /* Number of phrases in query */
+  SnippetPhrase *aPhrase;         /* Array of size nPhrase */
+  int iCurrent;                   /* First token of current snippet */
+};
+
+struct SnippetPhrase {
+  int nToken;                     /* Number of tokens in phrase */
+  char *pList;                    /* Pointer to start of phrase position list */
+  int iHead;                      /* Next value in position list */
+  char *pHead;                    /* Position list data following iHead */
+  int iTail;                      /* Next value in trailing position list */
+  char *pTail;                    /* Position list data following iTail */
+};
+
+struct SnippetFragment {
+  int iCol;                       /* Column snippet is extracted from */
+  int iPos;                       /* Index of first token in snippet */
+  u64 covered;                    /* Mask of query phrases covered */
+  u64 hlmask;                     /* Mask of snippet terms to highlight */
+};
+
+/*
+** This type is used as an fts3ExprIterate() context object while 
+** accumulating the data returned by the matchinfo() function.
+*/
+typedef struct MatchInfo MatchInfo;
+struct MatchInfo {
+  Fts3Cursor *pCursor;            /* FTS3 Cursor */
+  int nCol;                       /* Number of columns in table */
+  int nPhrase;                    /* Number of matchable phrases in query */
+  sqlite3_int64 nDoc;             /* Number of docs in database */
+  char flag;
+  u32 *aMatchinfo;                /* Pre-allocated buffer */
+};
+
+/*
+** An instance of this structure is used to manage a pair of buffers, each
+** (nElem * sizeof(u32)) bytes in size. See the MatchinfoBuffer code below
+** for details.
+*/
+struct MatchinfoBuffer {
+  u8 aRef[3];
+  int nElem;
+  int bGlobal;                    /* Set if global data is loaded */
+  char *zMatchinfo;
+  u32 aMatchinfo[1];
+};
+
+
+/*
+** The snippet() and offsets() functions both return text values. An instance
+** of the following structure is used to accumulate those values while the
+** functions are running. See fts3StringAppend() for details.
+*/
+typedef struct StrBuffer StrBuffer;
+struct StrBuffer {
+  char *z;                        /* Pointer to buffer containing string */
+  int n;                          /* Length of z in bytes (excl. nul-term) */
+  int nAlloc;                     /* Allocated size of buffer z in bytes */
+};
+
+
+/*************************************************************************
+** Start of MatchinfoBuffer code.
+*/
+
+/*
+** Allocate a two-slot MatchinfoBuffer object.
+*/
+static MatchinfoBuffer *fts3MIBufferNew(int nElem, const char *zMatchinfo){
+  MatchinfoBuffer *pRet;
+  int nByte = sizeof(u32) * (2*nElem + 1) + sizeof(MatchinfoBuffer);
+  int nStr = (int)strlen(zMatchinfo);
+
+  pRet = sqlite3_malloc(nByte + nStr+1);
+  if( pRet ){
+    memset(pRet, 0, nByte);
+    pRet->aMatchinfo[0] = (u8*)(&pRet->aMatchinfo[1]) - (u8*)pRet;
+    pRet->aMatchinfo[1+nElem] = pRet->aMatchinfo[0] + sizeof(u32)*(nElem+1);
+    pRet->nElem = nElem;
+    pRet->zMatchinfo = ((char*)pRet) + nByte;
+    memcpy(pRet->zMatchinfo, zMatchinfo, nStr+1);
+    pRet->aRef[0] = 1;
+  }
+
+  return pRet;
+}
+
+static void fts3MIBufferFree(void *p){
+  MatchinfoBuffer *pBuf = (MatchinfoBuffer*)((u8*)p - ((u32*)p)[-1]);
+
+  assert( (u32*)p==&pBuf->aMatchinfo[1] 
+       || (u32*)p==&pBuf->aMatchinfo[pBuf->nElem+2] 
+  );
+  if( (u32*)p==&pBuf->aMatchinfo[1] ){
+    pBuf->aRef[1] = 0;
+  }else{
+    pBuf->aRef[2] = 0;
+  }
+
+  if( pBuf->aRef[0]==0 && pBuf->aRef[1]==0 && pBuf->aRef[2]==0 ){
+    sqlite3_free(pBuf);
+  }
+}
+
+static void (*fts3MIBufferAlloc(MatchinfoBuffer *p, u32 **paOut))(void*){
+  void (*xRet)(void*) = 0;
+  u32 *aOut = 0;
+
+  if( p->aRef[1]==0 ){
+    p->aRef[1] = 1;
+    aOut = &p->aMatchinfo[1];
+    xRet = fts3MIBufferFree;
+  }
+  else if( p->aRef[2]==0 ){
+    p->aRef[2] = 1;
+    aOut = &p->aMatchinfo[p->nElem+2];
+    xRet = fts3MIBufferFree;
+  }else{
+    aOut = (u32*)sqlite3_malloc(p->nElem * sizeof(u32));
+    if( aOut ){
+      xRet = sqlite3_free;
+      if( p->bGlobal ) memcpy(aOut, &p->aMatchinfo[1], p->nElem*sizeof(u32));
+    }
+  }
+
+  *paOut = aOut;
+  return xRet;
+}
+
+static void fts3MIBufferSetGlobal(MatchinfoBuffer *p){
+  p->bGlobal = 1;
+  memcpy(&p->aMatchinfo[2+p->nElem], &p->aMatchinfo[1], p->nElem*sizeof(u32));
+}
+
+/*
+** Free a MatchinfoBuffer object allocated using fts3MIBufferNew()
+*/
+SQLITE_PRIVATE void sqlite3Fts3MIBufferFree(MatchinfoBuffer *p){
+  if( p ){
+    assert( p->aRef[0]==1 );
+    p->aRef[0] = 0;
+    if( p->aRef[0]==0 && p->aRef[1]==0 && p->aRef[2]==0 ){
+      sqlite3_free(p);
+    }
+  }
+}
+
+/* 
+** End of MatchinfoBuffer code.
+*************************************************************************/
+
+
+/*
+** This function is used to help iterate through a position-list. A position
+** list is a list of unique integers, sorted from smallest to largest. Each
+** element of the list is represented by an FTS3 varint that takes the value
+** of the difference between the current element and the previous one plus
+** two. For example, to store the position-list:
+**
+**     4 9 113
+**
+** the three varints:
+**
+**     6 7 106
+**
+** are encoded.
+**
+** When this function is called, *pp points to the start of an element of
+** the list. *piPos contains the value of the previous entry in the list.
+** After it returns, *piPos contains the value of the next element of the
+** list and *pp is advanced to the following varint.
+*/
+static void fts3GetDeltaPosition(char **pp, int *piPos){
+  int iVal;
+  *pp += fts3GetVarint32(*pp, &iVal);
+  *piPos += (iVal-2);
+}
+
+/*
+** Helper function for fts3ExprIterate() (see below).
+*/
+static int fts3ExprIterate2(
+  Fts3Expr *pExpr,                /* Expression to iterate phrases of */
+  int *piPhrase,                  /* Pointer to phrase counter */
+  int (*x)(Fts3Expr*,int,void*),  /* Callback function to invoke for phrases */
+  void *pCtx                      /* Second argument to pass to callback */
+){
+  int rc;                         /* Return code */
+  int eType = pExpr->eType;     /* Type of expression node pExpr */
+
+  if( eType!=FTSQUERY_PHRASE ){
+    assert( pExpr->pLeft && pExpr->pRight );
+    rc = fts3ExprIterate2(pExpr->pLeft, piPhrase, x, pCtx);
+    if( rc==SQLITE_OK && eType!=FTSQUERY_NOT ){
+      rc = fts3ExprIterate2(pExpr->pRight, piPhrase, x, pCtx);
+    }
+  }else{
+    rc = x(pExpr, *piPhrase, pCtx);
+    (*piPhrase)++;
+  }
+  return rc;
+}
+
+/*
+** Iterate through all phrase nodes in an FTS3 query, except those that
+** are part of a sub-tree that is the right-hand-side of a NOT operator.
+** For each phrase node found, the supplied callback function is invoked.
+**
+** If the callback function returns anything other than SQLITE_OK, 
+** the iteration is abandoned and the error code returned immediately.
+** Otherwise, SQLITE_OK is returned after a callback has been made for
+** all eligible phrase nodes.
+*/
+static int fts3ExprIterate(
+  Fts3Expr *pExpr,                /* Expression to iterate phrases of */
+  int (*x)(Fts3Expr*,int,void*),  /* Callback function to invoke for phrases */
+  void *pCtx                      /* Second argument to pass to callback */
+){
+  int iPhrase = 0;                /* Variable used as the phrase counter */
+  return fts3ExprIterate2(pExpr, &iPhrase, x, pCtx);
+}
+
+
+/*
+** This is an fts3ExprIterate() callback used while loading the doclists
+** for each phrase into Fts3Expr.aDoclist[]/nDoclist. See also
+** fts3ExprLoadDoclists().
+*/
+static int fts3ExprLoadDoclistsCb(Fts3Expr *pExpr, int iPhrase, void *ctx){
+  int rc = SQLITE_OK;
+  Fts3Phrase *pPhrase = pExpr->pPhrase;
+  LoadDoclistCtx *p = (LoadDoclistCtx *)ctx;
+
+  UNUSED_PARAMETER(iPhrase);
+
+  p->nPhrase++;
+  p->nToken += pPhrase->nToken;
+
+  return rc;
+}
+
+/*
+** Load the doclists for each phrase in the query associated with FTS3 cursor
+** pCsr. 
+**
+** If pnPhrase is not NULL, then *pnPhrase is set to the number of matchable 
+** phrases in the expression (all phrases except those directly or 
+** indirectly descended from the right-hand-side of a NOT operator). If 
+** pnToken is not NULL, then it is set to the number of tokens in all
+** matchable phrases of the expression.
+*/
+static int fts3ExprLoadDoclists(
+  Fts3Cursor *pCsr,               /* Fts3 cursor for current query */
+  int *pnPhrase,                  /* OUT: Number of phrases in query */
+  int *pnToken                    /* OUT: Number of tokens in query */
+){
+  int rc;                         /* Return Code */
+  LoadDoclistCtx sCtx = {0,0,0};  /* Context for fts3ExprIterate() */
+  sCtx.pCsr = pCsr;
+  rc = fts3ExprIterate(pCsr->pExpr, fts3ExprLoadDoclistsCb, (void *)&sCtx);
+  if( pnPhrase ) *pnPhrase = sCtx.nPhrase;
+  if( pnToken ) *pnToken = sCtx.nToken;
+  return rc;
+}
+
+static int fts3ExprPhraseCountCb(Fts3Expr *pExpr, int iPhrase, void *ctx){
+  (*(int *)ctx)++;
+  pExpr->iPhrase = iPhrase;
+  return SQLITE_OK;
+}
+static int fts3ExprPhraseCount(Fts3Expr *pExpr){
+  int nPhrase = 0;
+  (void)fts3ExprIterate(pExpr, fts3ExprPhraseCountCb, (void *)&nPhrase);
+  return nPhrase;
+}
+
+/*
+** Advance the position list iterator specified by the first two 
+** arguments so that it points to the first element with a value greater
+** than or equal to parameter iNext.
+*/
+static void fts3SnippetAdvance(char **ppIter, int *piIter, int iNext){
+  char *pIter = *ppIter;
+  if( pIter ){
+    int iIter = *piIter;
+
+    while( iIter<iNext ){
+      if( 0==(*pIter & 0xFE) ){
+        iIter = -1;
+        pIter = 0;
+        break;
+      }
+      fts3GetDeltaPosition(&pIter, &iIter);
+    }
+
+    *piIter = iIter;
+    *ppIter = pIter;
+  }
+}
+
+/*
+** Advance the snippet iterator to the next candidate snippet.
+*/
+static int fts3SnippetNextCandidate(SnippetIter *pIter){
+  int i;                          /* Loop counter */
+
+  if( pIter->iCurrent<0 ){
+    /* The SnippetIter object has just been initialized. The first snippet
+    ** candidate always starts at offset 0 (even if this candidate has a
+    ** score of 0.0).
+    */
+    pIter->iCurrent = 0;
+
+    /* Advance the 'head' iterator of each phrase to the first offset that
+    ** is greater than or equal to (iNext+nSnippet).
+    */
+    for(i=0; i<pIter->nPhrase; i++){
+      SnippetPhrase *pPhrase = &pIter->aPhrase[i];
+      fts3SnippetAdvance(&pPhrase->pHead, &pPhrase->iHead, pIter->nSnippet);
+    }
+  }else{
+    int iStart;
+    int iEnd = 0x7FFFFFFF;
+
+    for(i=0; i<pIter->nPhrase; i++){
+      SnippetPhrase *pPhrase = &pIter->aPhrase[i];
+      if( pPhrase->pHead && pPhrase->iHead<iEnd ){
+        iEnd = pPhrase->iHead;
+      }
+    }
+    if( iEnd==0x7FFFFFFF ){
+      return 1;
+    }
+
+    pIter->iCurrent = iStart = iEnd - pIter->nSnippet + 1;
+    for(i=0; i<pIter->nPhrase; i++){
+      SnippetPhrase *pPhrase = &pIter->aPhrase[i];
+      fts3SnippetAdvance(&pPhrase->pHead, &pPhrase->iHead, iEnd+1);
+      fts3SnippetAdvance(&pPhrase->pTail, &pPhrase->iTail, iStart);
+    }
+  }
+
+  return 0;
+}
+
+/*
+** Retrieve information about the current candidate snippet of snippet 
+** iterator pIter.
+*/
+static void fts3SnippetDetails(
+  SnippetIter *pIter,             /* Snippet iterator */
+  u64 mCovered,                   /* Bitmask of phrases already covered */
+  int *piToken,                   /* OUT: First token of proposed snippet */
+  int *piScore,                   /* OUT: "Score" for this snippet */
+  u64 *pmCover,                   /* OUT: Bitmask of phrases covered */
+  u64 *pmHighlight                /* OUT: Bitmask of terms to highlight */
+){
+  int iStart = pIter->iCurrent;   /* First token of snippet */
+  int iScore = 0;                 /* Score of this snippet */
+  int i;                          /* Loop counter */
+  u64 mCover = 0;                 /* Mask of phrases covered by this snippet */
+  u64 mHighlight = 0;             /* Mask of tokens to highlight in snippet */
+
+  for(i=0; i<pIter->nPhrase; i++){
+    SnippetPhrase *pPhrase = &pIter->aPhrase[i];
+    if( pPhrase->pTail ){
+      char *pCsr = pPhrase->pTail;
+      int iCsr = pPhrase->iTail;
+
+      while( iCsr<(iStart+pIter->nSnippet) ){
+        int j;
+        u64 mPhrase = (u64)1 << i;
+        u64 mPos = (u64)1 << (iCsr - iStart);
+        assert( iCsr>=iStart );
+        if( (mCover|mCovered)&mPhrase ){
+          iScore++;
+        }else{
+          iScore += 1000;
+        }
+        mCover |= mPhrase;
+
+        for(j=0; j<pPhrase->nToken; j++){
+          mHighlight |= (mPos>>j);
+        }
+
+        if( 0==(*pCsr & 0x0FE) ) break;
+        fts3GetDeltaPosition(&pCsr, &iCsr);
+      }
+    }
+  }
+
+  /* Set the output variables before returning. */
+  *piToken = iStart;
+  *piScore = iScore;
+  *pmCover = mCover;
+  *pmHighlight = mHighlight;
+}
+
+/*
+** This function is an fts3ExprIterate() callback used by fts3BestSnippet().
+** Each invocation populates an element of the SnippetIter.aPhrase[] array.
+*/
+static int fts3SnippetFindPositions(Fts3Expr *pExpr, int iPhrase, void *ctx){
+  SnippetIter *p = (SnippetIter *)ctx;
+  SnippetPhrase *pPhrase = &p->aPhrase[iPhrase];
+  char *pCsr;
+  int rc;
+
+  pPhrase->nToken = pExpr->pPhrase->nToken;
+  rc = sqlite3Fts3EvalPhrasePoslist(p->pCsr, pExpr, p->iCol, &pCsr);
+  assert( rc==SQLITE_OK || pCsr==0 );
+  if( pCsr ){
+    int iFirst = 0;
+    pPhrase->pList = pCsr;
+    fts3GetDeltaPosition(&pCsr, &iFirst);
+    assert( iFirst>=0 );
+    pPhrase->pHead = pCsr;
+    pPhrase->pTail = pCsr;
+    pPhrase->iHead = iFirst;
+    pPhrase->iTail = iFirst;
+  }else{
+    assert( rc!=SQLITE_OK || (
+       pPhrase->pList==0 && pPhrase->pHead==0 && pPhrase->pTail==0 
+    ));
+  }
+
+  return rc;
+}
+
+/*
+** Select the fragment of text consisting of nFragment contiguous tokens 
+** from column iCol that represent the "best" snippet. The best snippet
+** is the snippet with the highest score, where scores are calculated
+** by adding:
+**
+**   (a) +1 point for each occurrence of a matchable phrase in the snippet.
+**
+**   (b) +1000 points for the first occurrence of each matchable phrase in 
+**       the snippet for which the corresponding mCovered bit is not set.
+**
+** The selected snippet parameters are stored in structure *pFragment before
+** returning. The score of the selected snippet is stored in *piScore
+** before returning.
+*/
+static int fts3BestSnippet(
+  int nSnippet,                   /* Desired snippet length */
+  Fts3Cursor *pCsr,               /* Cursor to create snippet for */
+  int iCol,                       /* Index of column to create snippet from */
+  u64 mCovered,                   /* Mask of phrases already covered */
+  u64 *pmSeen,                    /* IN/OUT: Mask of phrases seen */
+  SnippetFragment *pFragment,     /* OUT: Best snippet found */
+  int *piScore                    /* OUT: Score of snippet pFragment */
+){
+  int rc;                         /* Return Code */
+  int nList;                      /* Number of phrases in expression */
+  SnippetIter sIter;              /* Iterates through snippet candidates */
+  int nByte;                      /* Number of bytes of space to allocate */
+  int iBestScore = -1;            /* Best snippet score found so far */
+  int i;                          /* Loop counter */
+
+  memset(&sIter, 0, sizeof(sIter));
+
+  /* Iterate through the phrases in the expression to count them. The same
+  ** callback makes sure the doclists are loaded for each phrase.
+  */
+  rc = fts3ExprLoadDoclists(pCsr, &nList, 0);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+
+  /* Now that it is known how many phrases there are, allocate and zero
+  ** the required space using malloc().
+  */
+  nByte = sizeof(SnippetPhrase) * nList;
+  sIter.aPhrase = (SnippetPhrase *)sqlite3_malloc(nByte);
+  if( !sIter.aPhrase ){
+    return SQLITE_NOMEM;
+  }
+  memset(sIter.aPhrase, 0, nByte);
+
+  /* Initialize the contents of the SnippetIter object. Then iterate through
+  ** the set of phrases in the expression to populate the aPhrase[] array.
+  */
+  sIter.pCsr = pCsr;
+  sIter.iCol = iCol;
+  sIter.nSnippet = nSnippet;
+  sIter.nPhrase = nList;
+  sIter.iCurrent = -1;
+  rc = fts3ExprIterate(pCsr->pExpr, fts3SnippetFindPositions, (void*)&sIter);
+  if( rc==SQLITE_OK ){
+
+    /* Set the *pmSeen output variable. */
+    for(i=0; i<nList; i++){
+      if( sIter.aPhrase[i].pHead ){
+        *pmSeen |= (u64)1 << i;
+      }
+    }
+
+    /* Loop through all candidate snippets. Store the best snippet in 
+     ** *pFragment. Store its associated 'score' in iBestScore.
+     */
+    pFragment->iCol = iCol;
+    while( !fts3SnippetNextCandidate(&sIter) ){
+      int iPos;
+      int iScore;
+      u64 mCover;
+      u64 mHighlite;
+      fts3SnippetDetails(&sIter, mCovered, &iPos, &iScore, &mCover,&mHighlite);
+      assert( iScore>=0 );
+      if( iScore>iBestScore ){
+        pFragment->iPos = iPos;
+        pFragment->hlmask = mHighlite;
+        pFragment->covered = mCover;
+        iBestScore = iScore;
+      }
+    }
+
+    *piScore = iBestScore;
+  }
+  sqlite3_free(sIter.aPhrase);
+  return rc;
+}
+
+
+/*
+** Append a string to the string-buffer passed as the first argument.
+**
+** If nAppend is negative, then the length of the string zAppend is
+** determined using strlen().
+*/
+static int fts3StringAppend(
+  StrBuffer *pStr,                /* Buffer to append to */
+  const char *zAppend,            /* Pointer to data to append to buffer */
+  int nAppend                     /* Size of zAppend in bytes (or -1) */
+){
+  if( nAppend<0 ){
+    nAppend = (int)strlen(zAppend);
+  }
+
+  /* If there is insufficient space allocated at StrBuffer.z, use realloc()
+  ** to grow the buffer until so that it is big enough to accomadate the
+  ** appended data.
+  */
+  if( pStr->n+nAppend+1>=pStr->nAlloc ){
+    int nAlloc = pStr->nAlloc+nAppend+100;
+    char *zNew = sqlite3_realloc(pStr->z, nAlloc);
+    if( !zNew ){
+      return SQLITE_NOMEM;
+    }
+    pStr->z = zNew;
+    pStr->nAlloc = nAlloc;
+  }
+  assert( pStr->z!=0 && (pStr->nAlloc >= pStr->n+nAppend+1) );
+
+  /* Append the data to the string buffer. */
+  memcpy(&pStr->z[pStr->n], zAppend, nAppend);
+  pStr->n += nAppend;
+  pStr->z[pStr->n] = '\0';
+
+  return SQLITE_OK;
+}
+
+/*
+** The fts3BestSnippet() function often selects snippets that end with a
+** query term. That is, the final term of the snippet is always a term
+** that requires highlighting. For example, if 'X' is a highlighted term
+** and '.' is a non-highlighted term, BestSnippet() may select:
+**
+**     ........X.....X
+**
+** This function "shifts" the beginning of the snippet forward in the 
+** document so that there are approximately the same number of 
+** non-highlighted terms to the right of the final highlighted term as there
+** are to the left of the first highlighted term. For example, to this:
+**
+**     ....X.....X....
+**
+** This is done as part of extracting the snippet text, not when selecting
+** the snippet. Snippet selection is done based on doclists only, so there
+** is no way for fts3BestSnippet() to know whether or not the document 
+** actually contains terms that follow the final highlighted term. 
+*/
+static int fts3SnippetShift(
+  Fts3Table *pTab,                /* FTS3 table snippet comes from */
+  int iLangid,                    /* Language id to use in tokenizing */
+  int nSnippet,                   /* Number of tokens desired for snippet */
+  const char *zDoc,               /* Document text to extract snippet from */
+  int nDoc,                       /* Size of buffer zDoc in bytes */
+  int *piPos,                     /* IN/OUT: First token of snippet */
+  u64 *pHlmask                    /* IN/OUT: Mask of tokens to highlight */
+){
+  u64 hlmask = *pHlmask;          /* Local copy of initial highlight-mask */
+
+  if( hlmask ){
+    int nLeft;                    /* Tokens to the left of first highlight */
+    int nRight;                   /* Tokens to the right of last highlight */
+    int nDesired;                 /* Ideal number of tokens to shift forward */
+
+    for(nLeft=0; !(hlmask & ((u64)1 << nLeft)); nLeft++);
+    for(nRight=0; !(hlmask & ((u64)1 << (nSnippet-1-nRight))); nRight++);
+    nDesired = (nLeft-nRight)/2;
+
+    /* Ideally, the start of the snippet should be pushed forward in the
+    ** document nDesired tokens. This block checks if there are actually
+    ** nDesired tokens to the right of the snippet. If so, *piPos and
+    ** *pHlMask are updated to shift the snippet nDesired tokens to the
+    ** right. Otherwise, the snippet is shifted by the number of tokens
+    ** available.
+    */
+    if( nDesired>0 ){
+      int nShift;                 /* Number of tokens to shift snippet by */
+      int iCurrent = 0;           /* Token counter */
+      int rc;                     /* Return Code */
+      sqlite3_tokenizer_module *pMod;
+      sqlite3_tokenizer_cursor *pC;
+      pMod = (sqlite3_tokenizer_module *)pTab->pTokenizer->pModule;
+
+      /* Open a cursor on zDoc/nDoc. Check if there are (nSnippet+nDesired)
+      ** or more tokens in zDoc/nDoc.
+      */
+      rc = sqlite3Fts3OpenTokenizer(pTab->pTokenizer, iLangid, zDoc, nDoc, &pC);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+      while( rc==SQLITE_OK && iCurrent<(nSnippet+nDesired) ){
+        const char *ZDUMMY; int DUMMY1 = 0, DUMMY2 = 0, DUMMY3 = 0;
+        rc = pMod->xNext(pC, &ZDUMMY, &DUMMY1, &DUMMY2, &DUMMY3, &iCurrent);
+      }
+      pMod->xClose(pC);
+      if( rc!=SQLITE_OK && rc!=SQLITE_DONE ){ return rc; }
+
+      nShift = (rc==SQLITE_DONE)+iCurrent-nSnippet;
+      assert( nShift<=nDesired );
+      if( nShift>0 ){
+        *piPos += nShift;
+        *pHlmask = hlmask >> nShift;
+      }
+    }
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Extract the snippet text for fragment pFragment from cursor pCsr and
+** append it to string buffer pOut.
+*/
+static int fts3SnippetText(
+  Fts3Cursor *pCsr,               /* FTS3 Cursor */
+  SnippetFragment *pFragment,     /* Snippet to extract */
+  int iFragment,                  /* Fragment number */
+  int isLast,                     /* True for final fragment in snippet */
+  int nSnippet,                   /* Number of tokens in extracted snippet */
+  const char *zOpen,              /* String inserted before highlighted term */
+  const char *zClose,             /* String inserted after highlighted term */
+  const char *zEllipsis,          /* String inserted between snippets */
+  StrBuffer *pOut                 /* Write output here */
+){
+  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
+  int rc;                         /* Return code */
+  const char *zDoc;               /* Document text to extract snippet from */
+  int nDoc;                       /* Size of zDoc in bytes */
+  int iCurrent = 0;               /* Current token number of document */
+  int iEnd = 0;                   /* Byte offset of end of current token */
+  int isShiftDone = 0;            /* True after snippet is shifted */
+  int iPos = pFragment->iPos;     /* First token of snippet */
+  u64 hlmask = pFragment->hlmask; /* Highlight-mask for snippet */
+  int iCol = pFragment->iCol+1;   /* Query column to extract text from */
+  sqlite3_tokenizer_module *pMod; /* Tokenizer module methods object */
+  sqlite3_tokenizer_cursor *pC;   /* Tokenizer cursor open on zDoc/nDoc */
+  
+  zDoc = (const char *)sqlite3_column_text(pCsr->pStmt, iCol);
+  if( zDoc==0 ){
+    if( sqlite3_column_type(pCsr->pStmt, iCol)!=SQLITE_NULL ){
+      return SQLITE_NOMEM;
+    }
+    return SQLITE_OK;
+  }
+  nDoc = sqlite3_column_bytes(pCsr->pStmt, iCol);
+
+  /* Open a token cursor on the document. */
+  pMod = (sqlite3_tokenizer_module *)pTab->pTokenizer->pModule;
+  rc = sqlite3Fts3OpenTokenizer(pTab->pTokenizer, pCsr->iLangid, zDoc,nDoc,&pC);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+
+  while( rc==SQLITE_OK ){
+    const char *ZDUMMY;           /* Dummy argument used with tokenizer */
+    int DUMMY1 = -1;              /* Dummy argument used with tokenizer */
+    int iBegin = 0;               /* Offset in zDoc of start of token */
+    int iFin = 0;                 /* Offset in zDoc of end of token */
+    int isHighlight = 0;          /* True for highlighted terms */
+
+    /* Variable DUMMY1 is initialized to a negative value above. Elsewhere
+    ** in the FTS code the variable that the third argument to xNext points to
+    ** is initialized to zero before the first (*but not necessarily
+    ** subsequent*) call to xNext(). This is done for a particular application
+    ** that needs to know whether or not the tokenizer is being used for
+    ** snippet generation or for some other purpose.
+    **
+    ** Extreme care is required when writing code to depend on this
+    ** initialization. It is not a documented part of the tokenizer interface.
+    ** If a tokenizer is used directly by any code outside of FTS, this
+    ** convention might not be respected.  */
+    rc = pMod->xNext(pC, &ZDUMMY, &DUMMY1, &iBegin, &iFin, &iCurrent);
+    if( rc!=SQLITE_OK ){
+      if( rc==SQLITE_DONE ){
+        /* Special case - the last token of the snippet is also the last token
+        ** of the column. Append any punctuation that occurred between the end
+        ** of the previous token and the end of the document to the output. 
+        ** Then break out of the loop. */
+        rc = fts3StringAppend(pOut, &zDoc[iEnd], -1);
+      }
+      break;
+    }
+    if( iCurrent<iPos ){ continue; }
+
+    if( !isShiftDone ){
+      int n = nDoc - iBegin;
+      rc = fts3SnippetShift(
+          pTab, pCsr->iLangid, nSnippet, &zDoc[iBegin], n, &iPos, &hlmask
+      );
+      isShiftDone = 1;
+
+      /* Now that the shift has been done, check if the initial "..." are
+      ** required. They are required if (a) this is not the first fragment,
+      ** or (b) this fragment does not begin at position 0 of its column. 
+      */
+      if( rc==SQLITE_OK ){
+        if( iPos>0 || iFragment>0 ){
+          rc = fts3StringAppend(pOut, zEllipsis, -1);
+        }else if( iBegin ){
+          rc = fts3StringAppend(pOut, zDoc, iBegin);
+        }
+      }
+      if( rc!=SQLITE_OK || iCurrent<iPos ) continue;
+    }
+
+    if( iCurrent>=(iPos+nSnippet) ){
+      if( isLast ){
+        rc = fts3StringAppend(pOut, zEllipsis, -1);
+      }
+      break;
+    }
+
+    /* Set isHighlight to true if this term should be highlighted. */
+    isHighlight = (hlmask & ((u64)1 << (iCurrent-iPos)))!=0;
+
+    if( iCurrent>iPos ) rc = fts3StringAppend(pOut, &zDoc[iEnd], iBegin-iEnd);
+    if( rc==SQLITE_OK && isHighlight ) rc = fts3StringAppend(pOut, zOpen, -1);
+    if( rc==SQLITE_OK ) rc = fts3StringAppend(pOut, &zDoc[iBegin], iFin-iBegin);
+    if( rc==SQLITE_OK && isHighlight ) rc = fts3StringAppend(pOut, zClose, -1);
+
+    iEnd = iFin;
+  }
+
+  pMod->xClose(pC);
+  return rc;
+}
+
+
+/*
+** This function is used to count the entries in a column-list (a 
+** delta-encoded list of term offsets within a single column of a single 
+** row). When this function is called, *ppCollist should point to the
+** beginning of the first varint in the column-list (the varint that
+** contains the position of the first matching term in the column data).
+** Before returning, *ppCollist is set to point to the first byte after
+** the last varint in the column-list (either the 0x00 signifying the end
+** of the position-list, or the 0x01 that precedes the column number of
+** the next column in the position-list).
+**
+** The number of elements in the column-list is returned.
+*/
+static int fts3ColumnlistCount(char **ppCollist){
+  char *pEnd = *ppCollist;
+  char c = 0;
+  int nEntry = 0;
+
+  /* A column-list is terminated by either a 0x01 or 0x00. */
+  while( 0xFE & (*pEnd | c) ){
+    c = *pEnd++ & 0x80;
+    if( !c ) nEntry++;
+  }
+
+  *ppCollist = pEnd;
+  return nEntry;
+}
+
+/*
+** This function gathers 'y' or 'b' data for a single phrase.
+*/
+static void fts3ExprLHits(
+  Fts3Expr *pExpr,                /* Phrase expression node */
+  MatchInfo *p                    /* Matchinfo context */
+){
+  Fts3Table *pTab = (Fts3Table *)p->pCursor->base.pVtab;
+  int iStart;
+  Fts3Phrase *pPhrase = pExpr->pPhrase;
+  char *pIter = pPhrase->doclist.pList;
+  int iCol = 0;
+
+  assert( p->flag==FTS3_MATCHINFO_LHITS_BM || p->flag==FTS3_MATCHINFO_LHITS );
+  if( p->flag==FTS3_MATCHINFO_LHITS ){
+    iStart = pExpr->iPhrase * p->nCol;
+  }else{
+    iStart = pExpr->iPhrase * ((p->nCol + 31) / 32);
+  }
+
+  while( 1 ){
+    int nHit = fts3ColumnlistCount(&pIter);
+    if( (pPhrase->iColumn>=pTab->nColumn || pPhrase->iColumn==iCol) ){
+      if( p->flag==FTS3_MATCHINFO_LHITS ){
+        p->aMatchinfo[iStart + iCol] = (u32)nHit;
+      }else if( nHit ){
+        p->aMatchinfo[iStart + (iCol+1)/32] |= (1 << (iCol&0x1F));
+      }
+    }
+    assert( *pIter==0x00 || *pIter==0x01 );
+    if( *pIter!=0x01 ) break;
+    pIter++;
+    pIter += fts3GetVarint32(pIter, &iCol);
+  }
+}
+
+/*
+** Gather the results for matchinfo directives 'y' and 'b'.
+*/
+static void fts3ExprLHitGather(
+  Fts3Expr *pExpr,
+  MatchInfo *p
+){
+  assert( (pExpr->pLeft==0)==(pExpr->pRight==0) );
+  if( pExpr->bEof==0 && pExpr->iDocid==p->pCursor->iPrevId ){
+    if( pExpr->pLeft ){
+      fts3ExprLHitGather(pExpr->pLeft, p);
+      fts3ExprLHitGather(pExpr->pRight, p);
+    }else{
+      fts3ExprLHits(pExpr, p);
+    }
+  }
+}
+
+/*
+** fts3ExprIterate() callback used to collect the "global" matchinfo stats
+** for a single query. 
+**
+** fts3ExprIterate() callback to load the 'global' elements of a
+** FTS3_MATCHINFO_HITS matchinfo array. The global stats are those elements 
+** of the matchinfo array that are constant for all rows returned by the 
+** current query.
+**
+** Argument pCtx is actually a pointer to a struct of type MatchInfo. This
+** function populates Matchinfo.aMatchinfo[] as follows:
+**
+**   for(iCol=0; iCol<nCol; iCol++){
+**     aMatchinfo[3*iPhrase*nCol + 3*iCol + 1] = X;
+**     aMatchinfo[3*iPhrase*nCol + 3*iCol + 2] = Y;
+**   }
+**
+** where X is the number of matches for phrase iPhrase is column iCol of all
+** rows of the table. Y is the number of rows for which column iCol contains
+** at least one instance of phrase iPhrase.
+**
+** If the phrase pExpr consists entirely of deferred tokens, then all X and
+** Y values are set to nDoc, where nDoc is the number of documents in the 
+** file system. This is done because the full-text index doclist is required
+** to calculate these values properly, and the full-text index doclist is
+** not available for deferred tokens.
+*/
+static int fts3ExprGlobalHitsCb(
+  Fts3Expr *pExpr,                /* Phrase expression node */
+  int iPhrase,                    /* Phrase number (numbered from zero) */
+  void *pCtx                      /* Pointer to MatchInfo structure */
+){
+  MatchInfo *p = (MatchInfo *)pCtx;
+  return sqlite3Fts3EvalPhraseStats(
+      p->pCursor, pExpr, &p->aMatchinfo[3*iPhrase*p->nCol]
+  );
+}
+
+/*
+** fts3ExprIterate() callback used to collect the "local" part of the
+** FTS3_MATCHINFO_HITS array. The local stats are those elements of the 
+** array that are different for each row returned by the query.
+*/
+static int fts3ExprLocalHitsCb(
+  Fts3Expr *pExpr,                /* Phrase expression node */
+  int iPhrase,                    /* Phrase number */
+  void *pCtx                      /* Pointer to MatchInfo structure */
+){
+  int rc = SQLITE_OK;
+  MatchInfo *p = (MatchInfo *)pCtx;
+  int iStart = iPhrase * p->nCol * 3;
+  int i;
+
+  for(i=0; i<p->nCol && rc==SQLITE_OK; i++){
+    char *pCsr;
+    rc = sqlite3Fts3EvalPhrasePoslist(p->pCursor, pExpr, i, &pCsr);
+    if( pCsr ){
+      p->aMatchinfo[iStart+i*3] = fts3ColumnlistCount(&pCsr);
+    }else{
+      p->aMatchinfo[iStart+i*3] = 0;
+    }
+  }
+
+  return rc;
+}
+
+static int fts3MatchinfoCheck(
+  Fts3Table *pTab, 
+  char cArg,
+  char **pzErr
+){
+  if( (cArg==FTS3_MATCHINFO_NPHRASE)
+   || (cArg==FTS3_MATCHINFO_NCOL)
+   || (cArg==FTS3_MATCHINFO_NDOC && pTab->bFts4)
+   || (cArg==FTS3_MATCHINFO_AVGLENGTH && pTab->bFts4)
+   || (cArg==FTS3_MATCHINFO_LENGTH && pTab->bHasDocsize)
+   || (cArg==FTS3_MATCHINFO_LCS)
+   || (cArg==FTS3_MATCHINFO_HITS)
+   || (cArg==FTS3_MATCHINFO_LHITS)
+   || (cArg==FTS3_MATCHINFO_LHITS_BM)
+  ){
+    return SQLITE_OK;
+  }
+  sqlite3Fts3ErrMsg(pzErr, "unrecognized matchinfo request: %c", cArg);
+  return SQLITE_ERROR;
+}
+
+static int fts3MatchinfoSize(MatchInfo *pInfo, char cArg){
+  int nVal;                       /* Number of integers output by cArg */
+
+  switch( cArg ){
+    case FTS3_MATCHINFO_NDOC:
+    case FTS3_MATCHINFO_NPHRASE: 
+    case FTS3_MATCHINFO_NCOL: 
+      nVal = 1;
+      break;
+
+    case FTS3_MATCHINFO_AVGLENGTH:
+    case FTS3_MATCHINFO_LENGTH:
+    case FTS3_MATCHINFO_LCS:
+      nVal = pInfo->nCol;
+      break;
+
+    case FTS3_MATCHINFO_LHITS:
+      nVal = pInfo->nCol * pInfo->nPhrase;
+      break;
+
+    case FTS3_MATCHINFO_LHITS_BM:
+      nVal = pInfo->nPhrase * ((pInfo->nCol + 31) / 32);
+      break;
+
+    default:
+      assert( cArg==FTS3_MATCHINFO_HITS );
+      nVal = pInfo->nCol * pInfo->nPhrase * 3;
+      break;
+  }
+
+  return nVal;
+}
+
+static int fts3MatchinfoSelectDoctotal(
+  Fts3Table *pTab,
+  sqlite3_stmt **ppStmt,
+  sqlite3_int64 *pnDoc,
+  const char **paLen
+){
+  sqlite3_stmt *pStmt;
+  const char *a;
+  sqlite3_int64 nDoc;
+
+  if( !*ppStmt ){
+    int rc = sqlite3Fts3SelectDoctotal(pTab, ppStmt);
+    if( rc!=SQLITE_OK ) return rc;
+  }
+  pStmt = *ppStmt;
+  assert( sqlite3_data_count(pStmt)==1 );
+
+  a = sqlite3_column_blob(pStmt, 0);
+  a += sqlite3Fts3GetVarint(a, &nDoc);
+  if( nDoc==0 ) return FTS_CORRUPT_VTAB;
+  *pnDoc = (u32)nDoc;
+
+  if( paLen ) *paLen = a;
+  return SQLITE_OK;
+}
+
+/*
+** An instance of the following structure is used to store state while 
+** iterating through a multi-column position-list corresponding to the
+** hits for a single phrase on a single row in order to calculate the
+** values for a matchinfo() FTS3_MATCHINFO_LCS request.
+*/
+typedef struct LcsIterator LcsIterator;
+struct LcsIterator {
+  Fts3Expr *pExpr;                /* Pointer to phrase expression */
+  int iPosOffset;                 /* Tokens count up to end of this phrase */
+  char *pRead;                    /* Cursor used to iterate through aDoclist */
+  int iPos;                       /* Current position */
+};
+
+/* 
+** If LcsIterator.iCol is set to the following value, the iterator has
+** finished iterating through all offsets for all columns.
+*/
+#define LCS_ITERATOR_FINISHED 0x7FFFFFFF;
+
+static int fts3MatchinfoLcsCb(
+  Fts3Expr *pExpr,                /* Phrase expression node */
+  int iPhrase,                    /* Phrase number (numbered from zero) */
+  void *pCtx                      /* Pointer to MatchInfo structure */
+){
+  LcsIterator *aIter = (LcsIterator *)pCtx;
+  aIter[iPhrase].pExpr = pExpr;
+  return SQLITE_OK;
+}
+
+/*
+** Advance the iterator passed as an argument to the next position. Return
+** 1 if the iterator is at EOF or if it now points to the start of the
+** position list for the next column.
+*/
+static int fts3LcsIteratorAdvance(LcsIterator *pIter){
+  char *pRead = pIter->pRead;
+  sqlite3_int64 iRead;
+  int rc = 0;
+
+  pRead += sqlite3Fts3GetVarint(pRead, &iRead);
+  if( iRead==0 || iRead==1 ){
+    pRead = 0;
+    rc = 1;
+  }else{
+    pIter->iPos += (int)(iRead-2);
+  }
+
+  pIter->pRead = pRead;
+  return rc;
+}
+  
+/*
+** This function implements the FTS3_MATCHINFO_LCS matchinfo() flag. 
+**
+** If the call is successful, the longest-common-substring lengths for each
+** column are written into the first nCol elements of the pInfo->aMatchinfo[] 
+** array before returning. SQLITE_OK is returned in this case.
+**
+** Otherwise, if an error occurs, an SQLite error code is returned and the
+** data written to the first nCol elements of pInfo->aMatchinfo[] is 
+** undefined.
+*/
+static int fts3MatchinfoLcs(Fts3Cursor *pCsr, MatchInfo *pInfo){
+  LcsIterator *aIter;
+  int i;
+  int iCol;
+  int nToken = 0;
+
+  /* Allocate and populate the array of LcsIterator objects. The array
+  ** contains one element for each matchable phrase in the query.
+  **/
+  aIter = sqlite3_malloc(sizeof(LcsIterator) * pCsr->nPhrase);
+  if( !aIter ) return SQLITE_NOMEM;
+  memset(aIter, 0, sizeof(LcsIterator) * pCsr->nPhrase);
+  (void)fts3ExprIterate(pCsr->pExpr, fts3MatchinfoLcsCb, (void*)aIter);
+
+  for(i=0; i<pInfo->nPhrase; i++){
+    LcsIterator *pIter = &aIter[i];
+    nToken -= pIter->pExpr->pPhrase->nToken;
+    pIter->iPosOffset = nToken;
+  }
+
+  for(iCol=0; iCol<pInfo->nCol; iCol++){
+    int nLcs = 0;                 /* LCS value for this column */
+    int nLive = 0;                /* Number of iterators in aIter not at EOF */
+
+    for(i=0; i<pInfo->nPhrase; i++){
+      int rc;
+      LcsIterator *pIt = &aIter[i];
+      rc = sqlite3Fts3EvalPhrasePoslist(pCsr, pIt->pExpr, iCol, &pIt->pRead);
+      if( rc!=SQLITE_OK ) return rc;
+      if( pIt->pRead ){
+        pIt->iPos = pIt->iPosOffset;
+        fts3LcsIteratorAdvance(&aIter[i]);
+        nLive++;
+      }
+    }
+
+    while( nLive>0 ){
+      LcsIterator *pAdv = 0;      /* The iterator to advance by one position */
+      int nThisLcs = 0;           /* LCS for the current iterator positions */
+
+      for(i=0; i<pInfo->nPhrase; i++){
+        LcsIterator *pIter = &aIter[i];
+        if( pIter->pRead==0 ){
+          /* This iterator is already at EOF for this column. */
+          nThisLcs = 0;
+        }else{
+          if( pAdv==0 || pIter->iPos<pAdv->iPos ){
+            pAdv = pIter;
+          }
+          if( nThisLcs==0 || pIter->iPos==pIter[-1].iPos ){
+            nThisLcs++;
+          }else{
+            nThisLcs = 1;
+          }
+          if( nThisLcs>nLcs ) nLcs = nThisLcs;
+        }
+      }
+      if( fts3LcsIteratorAdvance(pAdv) ) nLive--;
+    }
+
+    pInfo->aMatchinfo[iCol] = nLcs;
+  }
+
+  sqlite3_free(aIter);
+  return SQLITE_OK;
+}
+
+/*
+** Populate the buffer pInfo->aMatchinfo[] with an array of integers to
+** be returned by the matchinfo() function. Argument zArg contains the 
+** format string passed as the second argument to matchinfo (or the
+** default value "pcx" if no second argument was specified). The format
+** string has already been validated and the pInfo->aMatchinfo[] array
+** is guaranteed to be large enough for the output.
+**
+** If bGlobal is true, then populate all fields of the matchinfo() output.
+** If it is false, then assume that those fields that do not change between
+** rows (i.e. FTS3_MATCHINFO_NPHRASE, NCOL, NDOC, AVGLENGTH and part of HITS)
+** have already been populated.
+**
+** Return SQLITE_OK if successful, or an SQLite error code if an error 
+** occurs. If a value other than SQLITE_OK is returned, the state the
+** pInfo->aMatchinfo[] buffer is left in is undefined.
+*/
+static int fts3MatchinfoValues(
+  Fts3Cursor *pCsr,               /* FTS3 cursor object */
+  int bGlobal,                    /* True to grab the global stats */
+  MatchInfo *pInfo,               /* Matchinfo context object */
+  const char *zArg                /* Matchinfo format string */
+){
+  int rc = SQLITE_OK;
+  int i;
+  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
+  sqlite3_stmt *pSelect = 0;
+
+  for(i=0; rc==SQLITE_OK && zArg[i]; i++){
+    pInfo->flag = zArg[i];
+    switch( zArg[i] ){
+      case FTS3_MATCHINFO_NPHRASE:
+        if( bGlobal ) pInfo->aMatchinfo[0] = pInfo->nPhrase;
+        break;
+
+      case FTS3_MATCHINFO_NCOL:
+        if( bGlobal ) pInfo->aMatchinfo[0] = pInfo->nCol;
+        break;
+        
+      case FTS3_MATCHINFO_NDOC:
+        if( bGlobal ){
+          sqlite3_int64 nDoc = 0;
+          rc = fts3MatchinfoSelectDoctotal(pTab, &pSelect, &nDoc, 0);
+          pInfo->aMatchinfo[0] = (u32)nDoc;
+        }
+        break;
+
+      case FTS3_MATCHINFO_AVGLENGTH: 
+        if( bGlobal ){
+          sqlite3_int64 nDoc;     /* Number of rows in table */
+          const char *a;          /* Aggregate column length array */
+
+          rc = fts3MatchinfoSelectDoctotal(pTab, &pSelect, &nDoc, &a);
+          if( rc==SQLITE_OK ){
+            int iCol;
+            for(iCol=0; iCol<pInfo->nCol; iCol++){
+              u32 iVal;
+              sqlite3_int64 nToken;
+              a += sqlite3Fts3GetVarint(a, &nToken);
+              iVal = (u32)(((u32)(nToken&0xffffffff)+nDoc/2)/nDoc);
+              pInfo->aMatchinfo[iCol] = iVal;
+            }
+          }
+        }
+        break;
+
+      case FTS3_MATCHINFO_LENGTH: {
+        sqlite3_stmt *pSelectDocsize = 0;
+        rc = sqlite3Fts3SelectDocsize(pTab, pCsr->iPrevId, &pSelectDocsize);
+        if( rc==SQLITE_OK ){
+          int iCol;
+          const char *a = sqlite3_column_blob(pSelectDocsize, 0);
+          for(iCol=0; iCol<pInfo->nCol; iCol++){
+            sqlite3_int64 nToken;
+            a += sqlite3Fts3GetVarint(a, &nToken);
+            pInfo->aMatchinfo[iCol] = (u32)nToken;
+          }
+        }
+        sqlite3_reset(pSelectDocsize);
+        break;
+      }
+
+      case FTS3_MATCHINFO_LCS:
+        rc = fts3ExprLoadDoclists(pCsr, 0, 0);
+        if( rc==SQLITE_OK ){
+          rc = fts3MatchinfoLcs(pCsr, pInfo);
+        }
+        break;
+
+      case FTS3_MATCHINFO_LHITS_BM:
+      case FTS3_MATCHINFO_LHITS: {
+        int nZero = fts3MatchinfoSize(pInfo, zArg[i]) * sizeof(u32);
+        memset(pInfo->aMatchinfo, 0, nZero);
+        fts3ExprLHitGather(pCsr->pExpr, pInfo);
+        break;
+      }
+
+      default: {
+        Fts3Expr *pExpr;
+        assert( zArg[i]==FTS3_MATCHINFO_HITS );
+        pExpr = pCsr->pExpr;
+        rc = fts3ExprLoadDoclists(pCsr, 0, 0);
+        if( rc!=SQLITE_OK ) break;
+        if( bGlobal ){
+          if( pCsr->pDeferred ){
+            rc = fts3MatchinfoSelectDoctotal(pTab, &pSelect, &pInfo->nDoc, 0);
+            if( rc!=SQLITE_OK ) break;
+          }
+          rc = fts3ExprIterate(pExpr, fts3ExprGlobalHitsCb,(void*)pInfo);
+          sqlite3Fts3EvalTestDeferred(pCsr, &rc);
+          if( rc!=SQLITE_OK ) break;
+        }
+        (void)fts3ExprIterate(pExpr, fts3ExprLocalHitsCb,(void*)pInfo);
+        break;
+      }
+    }
+
+    pInfo->aMatchinfo += fts3MatchinfoSize(pInfo, zArg[i]);
+  }
+
+  sqlite3_reset(pSelect);
+  return rc;
+}
+
+
+/*
+** Populate pCsr->aMatchinfo[] with data for the current row. The 
+** 'matchinfo' data is an array of 32-bit unsigned integers (C type u32).
+*/
+static void fts3GetMatchinfo(
+  sqlite3_context *pCtx,        /* Return results here */
+  Fts3Cursor *pCsr,               /* FTS3 Cursor object */
+  const char *zArg                /* Second argument to matchinfo() function */
+){
+  MatchInfo sInfo;
+  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
+  int rc = SQLITE_OK;
+  int bGlobal = 0;                /* Collect 'global' stats as well as local */
+
+  u32 *aOut = 0;
+  void (*xDestroyOut)(void*) = 0;
+
+  memset(&sInfo, 0, sizeof(MatchInfo));
+  sInfo.pCursor = pCsr;
+  sInfo.nCol = pTab->nColumn;
+
+  /* If there is cached matchinfo() data, but the format string for the 
+  ** cache does not match the format string for this request, discard 
+  ** the cached data. */
+  if( pCsr->pMIBuffer && strcmp(pCsr->pMIBuffer->zMatchinfo, zArg) ){
+    sqlite3Fts3MIBufferFree(pCsr->pMIBuffer);
+    pCsr->pMIBuffer = 0;
+  }
+
+  /* If Fts3Cursor.pMIBuffer is NULL, then this is the first time the
+  ** matchinfo function has been called for this query. In this case 
+  ** allocate the array used to accumulate the matchinfo data and
+  ** initialize those elements that are constant for every row.
+  */
+  if( pCsr->pMIBuffer==0 ){
+    int nMatchinfo = 0;           /* Number of u32 elements in match-info */
+    int i;                        /* Used to iterate through zArg */
+
+    /* Determine the number of phrases in the query */
+    pCsr->nPhrase = fts3ExprPhraseCount(pCsr->pExpr);
+    sInfo.nPhrase = pCsr->nPhrase;
+
+    /* Determine the number of integers in the buffer returned by this call. */
+    for(i=0; zArg[i]; i++){
+      char *zErr = 0;
+      if( fts3MatchinfoCheck(pTab, zArg[i], &zErr) ){
+        sqlite3_result_error(pCtx, zErr, -1);
+        sqlite3_free(zErr);
+        return;
+      }
+      nMatchinfo += fts3MatchinfoSize(&sInfo, zArg[i]);
+    }
+
+    /* Allocate space for Fts3Cursor.aMatchinfo[] and Fts3Cursor.zMatchinfo. */
+    pCsr->pMIBuffer = fts3MIBufferNew(nMatchinfo, zArg);
+    if( !pCsr->pMIBuffer ) rc = SQLITE_NOMEM;
+
+    pCsr->isMatchinfoNeeded = 1;
+    bGlobal = 1;
+  }
+
+  if( rc==SQLITE_OK ){
+    xDestroyOut = fts3MIBufferAlloc(pCsr->pMIBuffer, &aOut);
+    if( xDestroyOut==0 ){
+      rc = SQLITE_NOMEM;
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    sInfo.aMatchinfo = aOut;
+    sInfo.nPhrase = pCsr->nPhrase;
+    rc = fts3MatchinfoValues(pCsr, bGlobal, &sInfo, zArg);
+    if( bGlobal ){
+      fts3MIBufferSetGlobal(pCsr->pMIBuffer);
+    }
+  }
+
+  if( rc!=SQLITE_OK ){
+    sqlite3_result_error_code(pCtx, rc);
+    if( xDestroyOut ) xDestroyOut(aOut);
+  }else{
+    int n = pCsr->pMIBuffer->nElem * sizeof(u32);
+    sqlite3_result_blob(pCtx, aOut, n, xDestroyOut);
+  }
+}
+
+/*
+** Implementation of snippet() function.
+*/
+SQLITE_PRIVATE void sqlite3Fts3Snippet(
+  sqlite3_context *pCtx,          /* SQLite function call context */
+  Fts3Cursor *pCsr,               /* Cursor object */
+  const char *zStart,             /* Snippet start text - "<b>" */
+  const char *zEnd,               /* Snippet end text - "</b>" */
+  const char *zEllipsis,          /* Snippet ellipsis text - "<b>...</b>" */
+  int iCol,                       /* Extract snippet from this column */
+  int nToken                      /* Approximate number of tokens in snippet */
+){
+  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
+  int rc = SQLITE_OK;
+  int i;
+  StrBuffer res = {0, 0, 0};
+
+  /* The returned text includes up to four fragments of text extracted from
+  ** the data in the current row. The first iteration of the for(...) loop
+  ** below attempts to locate a single fragment of text nToken tokens in 
+  ** size that contains at least one instance of all phrases in the query
+  ** expression that appear in the current row. If such a fragment of text
+  ** cannot be found, the second iteration of the loop attempts to locate
+  ** a pair of fragments, and so on.
+  */
+  int nSnippet = 0;               /* Number of fragments in this snippet */
+  SnippetFragment aSnippet[4];    /* Maximum of 4 fragments per snippet */
+  int nFToken = -1;               /* Number of tokens in each fragment */
+
+  if( !pCsr->pExpr ){
+    sqlite3_result_text(pCtx, "", 0, SQLITE_STATIC);
+    return;
+  }
+
+  for(nSnippet=1; 1; nSnippet++){
+
+    int iSnip;                    /* Loop counter 0..nSnippet-1 */
+    u64 mCovered = 0;             /* Bitmask of phrases covered by snippet */
+    u64 mSeen = 0;                /* Bitmask of phrases seen by BestSnippet() */
+
+    if( nToken>=0 ){
+      nFToken = (nToken+nSnippet-1) / nSnippet;
+    }else{
+      nFToken = -1 * nToken;
+    }
+
+    for(iSnip=0; iSnip<nSnippet; iSnip++){
+      int iBestScore = -1;        /* Best score of columns checked so far */
+      int iRead;                  /* Used to iterate through columns */
+      SnippetFragment *pFragment = &aSnippet[iSnip];
+
+      memset(pFragment, 0, sizeof(*pFragment));
+
+      /* Loop through all columns of the table being considered for snippets.
+      ** If the iCol argument to this function was negative, this means all
+      ** columns of the FTS3 table. Otherwise, only column iCol is considered.
+      */
+      for(iRead=0; iRead<pTab->nColumn; iRead++){
+        SnippetFragment sF = {0, 0, 0, 0};
+        int iS = 0;
+        if( iCol>=0 && iRead!=iCol ) continue;
+
+        /* Find the best snippet of nFToken tokens in column iRead. */
+        rc = fts3BestSnippet(nFToken, pCsr, iRead, mCovered, &mSeen, &sF, &iS);
+        if( rc!=SQLITE_OK ){
+          goto snippet_out;
+        }
+        if( iS>iBestScore ){
+          *pFragment = sF;
+          iBestScore = iS;
+        }
+      }
+
+      mCovered |= pFragment->covered;
+    }
+
+    /* If all query phrases seen by fts3BestSnippet() are present in at least
+    ** one of the nSnippet snippet fragments, break out of the loop.
+    */
+    assert( (mCovered&mSeen)==mCovered );
+    if( mSeen==mCovered || nSnippet==SizeofArray(aSnippet) ) break;
+  }
+
+  assert( nFToken>0 );
+
+  for(i=0; i<nSnippet && rc==SQLITE_OK; i++){
+    rc = fts3SnippetText(pCsr, &aSnippet[i], 
+        i, (i==nSnippet-1), nFToken, zStart, zEnd, zEllipsis, &res
+    );
+  }
+
+ snippet_out:
+  sqlite3Fts3SegmentsClose(pTab);
+  if( rc!=SQLITE_OK ){
+    sqlite3_result_error_code(pCtx, rc);
+    sqlite3_free(res.z);
+  }else{
+    sqlite3_result_text(pCtx, res.z, -1, sqlite3_free);
+  }
+}
+
+
+typedef struct TermOffset TermOffset;
+typedef struct TermOffsetCtx TermOffsetCtx;
+
+struct TermOffset {
+  char *pList;                    /* Position-list */
+  int iPos;                       /* Position just read from pList */
+  int iOff;                       /* Offset of this term from read positions */
+};
+
+struct TermOffsetCtx {
+  Fts3Cursor *pCsr;
+  int iCol;                       /* Column of table to populate aTerm for */
+  int iTerm;
+  sqlite3_int64 iDocid;
+  TermOffset *aTerm;
+};
+
+/*
+** This function is an fts3ExprIterate() callback used by sqlite3Fts3Offsets().
+*/
+static int fts3ExprTermOffsetInit(Fts3Expr *pExpr, int iPhrase, void *ctx){
+  TermOffsetCtx *p = (TermOffsetCtx *)ctx;
+  int nTerm;                      /* Number of tokens in phrase */
+  int iTerm;                      /* For looping through nTerm phrase terms */
+  char *pList;                    /* Pointer to position list for phrase */
+  int iPos = 0;                   /* First position in position-list */
+  int rc;
+
+  UNUSED_PARAMETER(iPhrase);
+  rc = sqlite3Fts3EvalPhrasePoslist(p->pCsr, pExpr, p->iCol, &pList);
+  nTerm = pExpr->pPhrase->nToken;
+  if( pList ){
+    fts3GetDeltaPosition(&pList, &iPos);
+    assert( iPos>=0 );
+  }
+
+  for(iTerm=0; iTerm<nTerm; iTerm++){
+    TermOffset *pT = &p->aTerm[p->iTerm++];
+    pT->iOff = nTerm-iTerm-1;
+    pT->pList = pList;
+    pT->iPos = iPos;
+  }
+
+  return rc;
+}
+
+/*
+** Implementation of offsets() function.
+*/
+SQLITE_PRIVATE void sqlite3Fts3Offsets(
+  sqlite3_context *pCtx,          /* SQLite function call context */
+  Fts3Cursor *pCsr                /* Cursor object */
+){
+  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
+  sqlite3_tokenizer_module const *pMod = pTab->pTokenizer->pModule;
+  int rc;                         /* Return Code */
+  int nToken;                     /* Number of tokens in query */
+  int iCol;                       /* Column currently being processed */
+  StrBuffer res = {0, 0, 0};      /* Result string */
+  TermOffsetCtx sCtx;             /* Context for fts3ExprTermOffsetInit() */
+
+  if( !pCsr->pExpr ){
+    sqlite3_result_text(pCtx, "", 0, SQLITE_STATIC);
+    return;
+  }
+
+  memset(&sCtx, 0, sizeof(sCtx));
+  assert( pCsr->isRequireSeek==0 );
+
+  /* Count the number of terms in the query */
+  rc = fts3ExprLoadDoclists(pCsr, 0, &nToken);
+  if( rc!=SQLITE_OK ) goto offsets_out;
+
+  /* Allocate the array of TermOffset iterators. */
+  sCtx.aTerm = (TermOffset *)sqlite3_malloc(sizeof(TermOffset)*nToken);
+  if( 0==sCtx.aTerm ){
+    rc = SQLITE_NOMEM;
+    goto offsets_out;
+  }
+  sCtx.iDocid = pCsr->iPrevId;
+  sCtx.pCsr = pCsr;
+
+  /* Loop through the table columns, appending offset information to 
+  ** string-buffer res for each column.
+  */
+  for(iCol=0; iCol<pTab->nColumn; iCol++){
+    sqlite3_tokenizer_cursor *pC; /* Tokenizer cursor */
+    const char *ZDUMMY;           /* Dummy argument used with xNext() */
+    int NDUMMY = 0;               /* Dummy argument used with xNext() */
+    int iStart = 0;
+    int iEnd = 0;
+    int iCurrent = 0;
+    const char *zDoc;
+    int nDoc;
+
+    /* Initialize the contents of sCtx.aTerm[] for column iCol. There is 
+    ** no way that this operation can fail, so the return code from
+    ** fts3ExprIterate() can be discarded.
+    */
+    sCtx.iCol = iCol;
+    sCtx.iTerm = 0;
+    (void)fts3ExprIterate(pCsr->pExpr, fts3ExprTermOffsetInit, (void*)&sCtx);
+
+    /* Retreive the text stored in column iCol. If an SQL NULL is stored 
+    ** in column iCol, jump immediately to the next iteration of the loop.
+    ** If an OOM occurs while retrieving the data (this can happen if SQLite
+    ** needs to transform the data from utf-16 to utf-8), return SQLITE_NOMEM 
+    ** to the caller. 
+    */
+    zDoc = (const char *)sqlite3_column_text(pCsr->pStmt, iCol+1);
+    nDoc = sqlite3_column_bytes(pCsr->pStmt, iCol+1);
+    if( zDoc==0 ){
+      if( sqlite3_column_type(pCsr->pStmt, iCol+1)==SQLITE_NULL ){
+        continue;
+      }
+      rc = SQLITE_NOMEM;
+      goto offsets_out;
+    }
+
+    /* Initialize a tokenizer iterator to iterate through column iCol. */
+    rc = sqlite3Fts3OpenTokenizer(pTab->pTokenizer, pCsr->iLangid,
+        zDoc, nDoc, &pC
+    );
+    if( rc!=SQLITE_OK ) goto offsets_out;
+
+    rc = pMod->xNext(pC, &ZDUMMY, &NDUMMY, &iStart, &iEnd, &iCurrent);
+    while( rc==SQLITE_OK ){
+      int i;                      /* Used to loop through terms */
+      int iMinPos = 0x7FFFFFFF;   /* Position of next token */
+      TermOffset *pTerm = 0;      /* TermOffset associated with next token */
+
+      for(i=0; i<nToken; i++){
+        TermOffset *pT = &sCtx.aTerm[i];
+        if( pT->pList && (pT->iPos-pT->iOff)<iMinPos ){
+          iMinPos = pT->iPos-pT->iOff;
+          pTerm = pT;
+        }
+      }
+
+      if( !pTerm ){
+        /* All offsets for this column have been gathered. */
+        rc = SQLITE_DONE;
+      }else{
+        assert( iCurrent<=iMinPos );
+        if( 0==(0xFE&*pTerm->pList) ){
+          pTerm->pList = 0;
+        }else{
+          fts3GetDeltaPosition(&pTerm->pList, &pTerm->iPos);
+        }
+        while( rc==SQLITE_OK && iCurrent<iMinPos ){
+          rc = pMod->xNext(pC, &ZDUMMY, &NDUMMY, &iStart, &iEnd, &iCurrent);
+        }
+        if( rc==SQLITE_OK ){
+          char aBuffer[64];
+          sqlite3_snprintf(sizeof(aBuffer), aBuffer, 
+              "%d %d %d %d ", iCol, pTerm-sCtx.aTerm, iStart, iEnd-iStart
+          );
+          rc = fts3StringAppend(&res, aBuffer, -1);
+        }else if( rc==SQLITE_DONE && pTab->zContentTbl==0 ){
+          rc = FTS_CORRUPT_VTAB;
+        }
+      }
+    }
+    if( rc==SQLITE_DONE ){
+      rc = SQLITE_OK;
+    }
+
+    pMod->xClose(pC);
+    if( rc!=SQLITE_OK ) goto offsets_out;
+  }
+
+ offsets_out:
+  sqlite3_free(sCtx.aTerm);
+  assert( rc!=SQLITE_DONE );
+  sqlite3Fts3SegmentsClose(pTab);
+  if( rc!=SQLITE_OK ){
+    sqlite3_result_error_code(pCtx,  rc);
+    sqlite3_free(res.z);
+  }else{
+    sqlite3_result_text(pCtx, res.z, res.n-1, sqlite3_free);
+  }
+  return;
+}
+
+/*
+** Implementation of matchinfo() function.
+*/
+SQLITE_PRIVATE void sqlite3Fts3Matchinfo(
+  sqlite3_context *pContext,      /* Function call context */
+  Fts3Cursor *pCsr,               /* FTS3 table cursor */
+  const char *zArg                /* Second arg to matchinfo() function */
+){
+  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
+  const char *zFormat;
+
+  if( zArg ){
+    zFormat = zArg;
+  }else{
+    zFormat = FTS3_MATCHINFO_DEFAULT;
+  }
+
+  if( !pCsr->pExpr ){
+    sqlite3_result_blob(pContext, "", 0, SQLITE_STATIC);
+    return;
+  }else{
+    /* Retrieve matchinfo() data. */
+    fts3GetMatchinfo(pContext, pCsr, zFormat);
+    sqlite3Fts3SegmentsClose(pTab);
+  }
+}
+
+#endif
+
+/************** End of fts3_snippet.c ****************************************/
+/************** Begin file fts3_unicode.c ************************************/
+/*
+** 2012 May 24
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** Implementation of the "unicode" full-text-search tokenizer.
+*/
+
+#ifndef SQLITE_DISABLE_FTS3_UNICODE
+
+/* #include "fts3Int.h" */
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
+
+/* #include <assert.h> */
+/* #include <stdlib.h> */
+/* #include <stdio.h> */
+/* #include <string.h> */
+
+/* #include "fts3_tokenizer.h" */
+
+/*
+** The following two macros - READ_UTF8 and WRITE_UTF8 - have been copied
+** from the sqlite3 source file utf.c. If this file is compiled as part
+** of the amalgamation, they are not required.
+*/
+#ifndef SQLITE_AMALGAMATION
+
+static const unsigned char sqlite3Utf8Trans1[] = {
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+  0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+  0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x00, 0x01, 0x02, 0x03, 0x00, 0x01, 0x00, 0x00,
+};
+
+#define READ_UTF8(zIn, zTerm, c)                           \
+  c = *(zIn++);                                            \
+  if( c>=0xc0 ){                                           \
+    c = sqlite3Utf8Trans1[c-0xc0];                         \
+    while( zIn!=zTerm && (*zIn & 0xc0)==0x80 ){            \
+      c = (c<<6) + (0x3f & *(zIn++));                      \
+    }                                                      \
+    if( c<0x80                                             \
+        || (c&0xFFFFF800)==0xD800                          \
+        || (c&0xFFFFFFFE)==0xFFFE ){  c = 0xFFFD; }        \
+  }
+
+#define WRITE_UTF8(zOut, c) {                          \
+  if( c<0x00080 ){                                     \
+    *zOut++ = (u8)(c&0xFF);                            \
+  }                                                    \
+  else if( c<0x00800 ){                                \
+    *zOut++ = 0xC0 + (u8)((c>>6)&0x1F);                \
+    *zOut++ = 0x80 + (u8)(c & 0x3F);                   \
+  }                                                    \
+  else if( c<0x10000 ){                                \
+    *zOut++ = 0xE0 + (u8)((c>>12)&0x0F);               \
+    *zOut++ = 0x80 + (u8)((c>>6) & 0x3F);              \
+    *zOut++ = 0x80 + (u8)(c & 0x3F);                   \
+  }else{                                               \
+    *zOut++ = 0xF0 + (u8)((c>>18) & 0x07);             \
+    *zOut++ = 0x80 + (u8)((c>>12) & 0x3F);             \
+    *zOut++ = 0x80 + (u8)((c>>6) & 0x3F);              \
+    *zOut++ = 0x80 + (u8)(c & 0x3F);                   \
+  }                                                    \
+}
+
+#endif /* ifndef SQLITE_AMALGAMATION */
+
+typedef struct unicode_tokenizer unicode_tokenizer;
+typedef struct unicode_cursor unicode_cursor;
+
+struct unicode_tokenizer {
+  sqlite3_tokenizer base;
+  int bRemoveDiacritic;
+  int nException;
+  int *aiException;
+};
+
+struct unicode_cursor {
+  sqlite3_tokenizer_cursor base;
+  const unsigned char *aInput;    /* Input text being tokenized */
+  int nInput;                     /* Size of aInput[] in bytes */
+  int iOff;                       /* Current offset within aInput[] */
+  int iToken;                     /* Index of next token to be returned */
+  char *zToken;                   /* storage for current token */
+  int nAlloc;                     /* space allocated at zToken */
+};
+
+
+/*
+** Destroy a tokenizer allocated by unicodeCreate().
+*/
+static int unicodeDestroy(sqlite3_tokenizer *pTokenizer){
+  if( pTokenizer ){
+    unicode_tokenizer *p = (unicode_tokenizer *)pTokenizer;
+    sqlite3_free(p->aiException);
+    sqlite3_free(p);
+  }
+  return SQLITE_OK;
+}
+
+/*
+** As part of a tokenchars= or separators= option, the CREATE VIRTUAL TABLE
+** statement has specified that the tokenizer for this table shall consider
+** all characters in string zIn/nIn to be separators (if bAlnum==0) or
+** token characters (if bAlnum==1).
+**
+** For each codepoint in the zIn/nIn string, this function checks if the
+** sqlite3FtsUnicodeIsalnum() function already returns the desired result.
+** If so, no action is taken. Otherwise, the codepoint is added to the 
+** unicode_tokenizer.aiException[] array. For the purposes of tokenization,
+** the return value of sqlite3FtsUnicodeIsalnum() is inverted for all
+** codepoints in the aiException[] array.
+**
+** If a standalone diacritic mark (one that sqlite3FtsUnicodeIsdiacritic()
+** identifies as a diacritic) occurs in the zIn/nIn string it is ignored.
+** It is not possible to change the behavior of the tokenizer with respect
+** to these codepoints.
+*/
+static int unicodeAddExceptions(
+  unicode_tokenizer *p,           /* Tokenizer to add exceptions to */
+  int bAlnum,                     /* Replace Isalnum() return value with this */
+  const char *zIn,                /* Array of characters to make exceptions */
+  int nIn                         /* Length of z in bytes */
+){
+  const unsigned char *z = (const unsigned char *)zIn;
+  const unsigned char *zTerm = &z[nIn];
+  int iCode;
+  int nEntry = 0;
+
+  assert( bAlnum==0 || bAlnum==1 );
+
+  while( z<zTerm ){
+    READ_UTF8(z, zTerm, iCode);
+    assert( (sqlite3FtsUnicodeIsalnum(iCode) & 0xFFFFFFFE)==0 );
+    if( sqlite3FtsUnicodeIsalnum(iCode)!=bAlnum 
+     && sqlite3FtsUnicodeIsdiacritic(iCode)==0 
+    ){
+      nEntry++;
+    }
+  }
+
+  if( nEntry ){
+    int *aNew;                    /* New aiException[] array */
+    int nNew;                     /* Number of valid entries in array aNew[] */
+
+    aNew = sqlite3_realloc(p->aiException, (p->nException+nEntry)*sizeof(int));
+    if( aNew==0 ) return SQLITE_NOMEM;
+    nNew = p->nException;
+
+    z = (const unsigned char *)zIn;
+    while( z<zTerm ){
+      READ_UTF8(z, zTerm, iCode);
+      if( sqlite3FtsUnicodeIsalnum(iCode)!=bAlnum 
+       && sqlite3FtsUnicodeIsdiacritic(iCode)==0
+      ){
+        int i, j;
+        for(i=0; i<nNew && aNew[i]<iCode; i++);
+        for(j=nNew; j>i; j--) aNew[j] = aNew[j-1];
+        aNew[i] = iCode;
+        nNew++;
+      }
+    }
+    p->aiException = aNew;
+    p->nException = nNew;
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Return true if the p->aiException[] array contains the value iCode.
+*/
+static int unicodeIsException(unicode_tokenizer *p, int iCode){
+  if( p->nException>0 ){
+    int *a = p->aiException;
+    int iLo = 0;
+    int iHi = p->nException-1;
+
+    while( iHi>=iLo ){
+      int iTest = (iHi + iLo) / 2;
+      if( iCode==a[iTest] ){
+        return 1;
+      }else if( iCode>a[iTest] ){
+        iLo = iTest+1;
+      }else{
+        iHi = iTest-1;
+      }
+    }
+  }
+
+  return 0;
+}
+
+/*
+** Return true if, for the purposes of tokenization, codepoint iCode is
+** considered a token character (not a separator).
+*/
+static int unicodeIsAlnum(unicode_tokenizer *p, int iCode){
+  assert( (sqlite3FtsUnicodeIsalnum(iCode) & 0xFFFFFFFE)==0 );
+  return sqlite3FtsUnicodeIsalnum(iCode) ^ unicodeIsException(p, iCode);
+}
+
+/*
+** Create a new tokenizer instance.
+*/
+static int unicodeCreate(
+  int nArg,                       /* Size of array argv[] */
+  const char * const *azArg,      /* Tokenizer creation arguments */
+  sqlite3_tokenizer **pp          /* OUT: New tokenizer handle */
+){
+  unicode_tokenizer *pNew;        /* New tokenizer object */
+  int i;
+  int rc = SQLITE_OK;
+
+  pNew = (unicode_tokenizer *) sqlite3_malloc(sizeof(unicode_tokenizer));
+  if( pNew==NULL ) return SQLITE_NOMEM;
+  memset(pNew, 0, sizeof(unicode_tokenizer));
+  pNew->bRemoveDiacritic = 1;
+
+  for(i=0; rc==SQLITE_OK && i<nArg; i++){
+    const char *z = azArg[i];
+    int n = (int)strlen(z);
+
+    if( n==19 && memcmp("remove_diacritics=1", z, 19)==0 ){
+      pNew->bRemoveDiacritic = 1;
+    }
+    else if( n==19 && memcmp("remove_diacritics=0", z, 19)==0 ){
+      pNew->bRemoveDiacritic = 0;
+    }
+    else if( n>=11 && memcmp("tokenchars=", z, 11)==0 ){
+      rc = unicodeAddExceptions(pNew, 1, &z[11], n-11);
+    }
+    else if( n>=11 && memcmp("separators=", z, 11)==0 ){
+      rc = unicodeAddExceptions(pNew, 0, &z[11], n-11);
+    }
+    else{
+      /* Unrecognized argument */
+      rc  = SQLITE_ERROR;
+    }
+  }
+
+  if( rc!=SQLITE_OK ){
+    unicodeDestroy((sqlite3_tokenizer *)pNew);
+    pNew = 0;
+  }
+  *pp = (sqlite3_tokenizer *)pNew;
+  return rc;
+}
+
+/*
+** Prepare to begin tokenizing a particular string.  The input
+** string to be tokenized is pInput[0..nBytes-1].  A cursor
+** used to incrementally tokenize this string is returned in 
+** *ppCursor.
+*/
+static int unicodeOpen(
+  sqlite3_tokenizer *p,           /* The tokenizer */
+  const char *aInput,             /* Input string */
+  int nInput,                     /* Size of string aInput in bytes */
+  sqlite3_tokenizer_cursor **pp   /* OUT: New cursor object */
+){
+  unicode_cursor *pCsr;
+
+  pCsr = (unicode_cursor *)sqlite3_malloc(sizeof(unicode_cursor));
+  if( pCsr==0 ){
+    return SQLITE_NOMEM;
+  }
+  memset(pCsr, 0, sizeof(unicode_cursor));
+
+  pCsr->aInput = (const unsigned char *)aInput;
+  if( aInput==0 ){
+    pCsr->nInput = 0;
+  }else if( nInput<0 ){
+    pCsr->nInput = (int)strlen(aInput);
+  }else{
+    pCsr->nInput = nInput;
+  }
+
+  *pp = &pCsr->base;
+  UNUSED_PARAMETER(p);
+  return SQLITE_OK;
+}
+
+/*
+** Close a tokenization cursor previously opened by a call to
+** simpleOpen() above.
+*/
+static int unicodeClose(sqlite3_tokenizer_cursor *pCursor){
+  unicode_cursor *pCsr = (unicode_cursor *) pCursor;
+  sqlite3_free(pCsr->zToken);
+  sqlite3_free(pCsr);
+  return SQLITE_OK;
+}
+
+/*
+** Extract the next token from a tokenization cursor.  The cursor must
+** have been opened by a prior call to simpleOpen().
+*/
+static int unicodeNext(
+  sqlite3_tokenizer_cursor *pC,   /* Cursor returned by simpleOpen */
+  const char **paToken,           /* OUT: Token text */
+  int *pnToken,                   /* OUT: Number of bytes at *paToken */
+  int *piStart,                   /* OUT: Starting offset of token */
+  int *piEnd,                     /* OUT: Ending offset of token */
+  int *piPos                      /* OUT: Position integer of token */
+){
+  unicode_cursor *pCsr = (unicode_cursor *)pC;
+  unicode_tokenizer *p = ((unicode_tokenizer *)pCsr->base.pTokenizer);
+  int iCode = 0;
+  char *zOut;
+  const unsigned char *z = &pCsr->aInput[pCsr->iOff];
+  const unsigned char *zStart = z;
+  const unsigned char *zEnd;
+  const unsigned char *zTerm = &pCsr->aInput[pCsr->nInput];
+
+  /* Scan past any delimiter characters before the start of the next token.
+  ** Return SQLITE_DONE early if this takes us all the way to the end of 
+  ** the input.  */
+  while( z<zTerm ){
+    READ_UTF8(z, zTerm, iCode);
+    if( unicodeIsAlnum(p, iCode) ) break;
+    zStart = z;
+  }
+  if( zStart>=zTerm ) return SQLITE_DONE;
+
+  zOut = pCsr->zToken;
+  do {
+    int iOut;
+
+    /* Grow the output buffer if required. */
+    if( (zOut-pCsr->zToken)>=(pCsr->nAlloc-4) ){
+      char *zNew = sqlite3_realloc(pCsr->zToken, pCsr->nAlloc+64);
+      if( !zNew ) return SQLITE_NOMEM;
+      zOut = &zNew[zOut - pCsr->zToken];
+      pCsr->zToken = zNew;
+      pCsr->nAlloc += 64;
+    }
+
+    /* Write the folded case of the last character read to the output */
+    zEnd = z;
+    iOut = sqlite3FtsUnicodeFold(iCode, p->bRemoveDiacritic);
+    if( iOut ){
+      WRITE_UTF8(zOut, iOut);
+    }
+
+    /* If the cursor is not at EOF, read the next character */
+    if( z>=zTerm ) break;
+    READ_UTF8(z, zTerm, iCode);
+  }while( unicodeIsAlnum(p, iCode) 
+       || sqlite3FtsUnicodeIsdiacritic(iCode)
+  );
+
+  /* Set the output variables and return. */
+  pCsr->iOff = (int)(z - pCsr->aInput);
+  *paToken = pCsr->zToken;
+  *pnToken = (int)(zOut - pCsr->zToken);
+  *piStart = (int)(zStart - pCsr->aInput);
+  *piEnd = (int)(zEnd - pCsr->aInput);
+  *piPos = pCsr->iToken++;
+  return SQLITE_OK;
+}
+
+/*
+** Set *ppModule to a pointer to the sqlite3_tokenizer_module 
+** structure for the unicode tokenizer.
+*/
+SQLITE_PRIVATE void sqlite3Fts3UnicodeTokenizer(sqlite3_tokenizer_module const **ppModule){
+  static const sqlite3_tokenizer_module module = {
+    0,
+    unicodeCreate,
+    unicodeDestroy,
+    unicodeOpen,
+    unicodeClose,
+    unicodeNext,
+    0,
+  };
+  *ppModule = &module;
+}
+
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */
+#endif /* ifndef SQLITE_DISABLE_FTS3_UNICODE */
+
+/************** End of fts3_unicode.c ****************************************/
+/************** Begin file fts3_unicode2.c ***********************************/
+/*
+** 2012 May 25
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+*/
+
+/*
+** DO NOT EDIT THIS MACHINE GENERATED FILE.
+*/
+
+#ifndef SQLITE_DISABLE_FTS3_UNICODE
+#if defined(SQLITE_ENABLE_FTS3) || defined(SQLITE_ENABLE_FTS4)
+
+/* #include <assert.h> */
+
+/*
+** Return true if the argument corresponds to a unicode codepoint
+** classified as either a letter or a number. Otherwise false.
+**
+** The results are undefined if the value passed to this function
+** is less than zero.
+*/
+SQLITE_PRIVATE int sqlite3FtsUnicodeIsalnum(int c){
+  /* Each unsigned integer in the following array corresponds to a contiguous
+  ** range of unicode codepoints that are not either letters or numbers (i.e.
+  ** codepoints for which this function should return 0).
+  **
+  ** The most significant 22 bits in each 32-bit value contain the first 
+  ** codepoint in the range. The least significant 10 bits are used to store
+  ** the size of the range (always at least 1). In other words, the value 
+  ** ((C<<22) + N) represents a range of N codepoints starting with codepoint 
+  ** C. It is not possible to represent a range larger than 1023 codepoints 
+  ** using this format.
+  */
+  static const unsigned int aEntry[] = {
+    0x00000030, 0x0000E807, 0x00016C06, 0x0001EC2F, 0x0002AC07,
+    0x0002D001, 0x0002D803, 0x0002EC01, 0x0002FC01, 0x00035C01,
+    0x0003DC01, 0x000B0804, 0x000B480E, 0x000B9407, 0x000BB401,
+    0x000BBC81, 0x000DD401, 0x000DF801, 0x000E1002, 0x000E1C01,
+    0x000FD801, 0x00120808, 0x00156806, 0x00162402, 0x00163C01,
+    0x00164437, 0x0017CC02, 0x00180005, 0x00181816, 0x00187802,
+    0x00192C15, 0x0019A804, 0x0019C001, 0x001B5001, 0x001B580F,
+    0x001B9C07, 0x001BF402, 0x001C000E, 0x001C3C01, 0x001C4401,
+    0x001CC01B, 0x001E980B, 0x001FAC09, 0x001FD804, 0x00205804,
+    0x00206C09, 0x00209403, 0x0020A405, 0x0020C00F, 0x00216403,
+    0x00217801, 0x0023901B, 0x00240004, 0x0024E803, 0x0024F812,
+    0x00254407, 0x00258804, 0x0025C001, 0x00260403, 0x0026F001,
+    0x0026F807, 0x00271C02, 0x00272C03, 0x00275C01, 0x00278802,
+    0x0027C802, 0x0027E802, 0x00280403, 0x0028F001, 0x0028F805,
+    0x00291C02, 0x00292C03, 0x00294401, 0x0029C002, 0x0029D401,
+    0x002A0403, 0x002AF001, 0x002AF808, 0x002B1C03, 0x002B2C03,
+    0x002B8802, 0x002BC002, 0x002C0403, 0x002CF001, 0x002CF807,
+    0x002D1C02, 0x002D2C03, 0x002D5802, 0x002D8802, 0x002DC001,
+    0x002E0801, 0x002EF805, 0x002F1803, 0x002F2804, 0x002F5C01,
+    0x002FCC08, 0x00300403, 0x0030F807, 0x00311803, 0x00312804,
+    0x00315402, 0x00318802, 0x0031FC01, 0x00320802, 0x0032F001,
+    0x0032F807, 0x00331803, 0x00332804, 0x00335402, 0x00338802,
+    0x00340802, 0x0034F807, 0x00351803, 0x00352804, 0x00355C01,
+    0x00358802, 0x0035E401, 0x00360802, 0x00372801, 0x00373C06,
+    0x00375801, 0x00376008, 0x0037C803, 0x0038C401, 0x0038D007,
+    0x0038FC01, 0x00391C09, 0x00396802, 0x003AC401, 0x003AD006,
+    0x003AEC02, 0x003B2006, 0x003C041F, 0x003CD00C, 0x003DC417,
+    0x003E340B, 0x003E6424, 0x003EF80F, 0x003F380D, 0x0040AC14,
+    0x00412806, 0x00415804, 0x00417803, 0x00418803, 0x00419C07,
+    0x0041C404, 0x0042080C, 0x00423C01, 0x00426806, 0x0043EC01,
+    0x004D740C, 0x004E400A, 0x00500001, 0x0059B402, 0x005A0001,
+    0x005A6C02, 0x005BAC03, 0x005C4803, 0x005CC805, 0x005D4802,
+    0x005DC802, 0x005ED023, 0x005F6004, 0x005F7401, 0x0060000F,
+    0x0062A401, 0x0064800C, 0x0064C00C, 0x00650001, 0x00651002,
+    0x0066C011, 0x00672002, 0x00677822, 0x00685C05, 0x00687802,
+    0x0069540A, 0x0069801D, 0x0069FC01, 0x006A8007, 0x006AA006,
+    0x006C0005, 0x006CD011, 0x006D6823, 0x006E0003, 0x006E840D,
+    0x006F980E, 0x006FF004, 0x00709014, 0x0070EC05, 0x0071F802,
+    0x00730008, 0x00734019, 0x0073B401, 0x0073C803, 0x00770027,
+    0x0077F004, 0x007EF401, 0x007EFC03, 0x007F3403, 0x007F7403,
+    0x007FB403, 0x007FF402, 0x00800065, 0x0081A806, 0x0081E805,
+    0x00822805, 0x0082801A, 0x00834021, 0x00840002, 0x00840C04,
+    0x00842002, 0x00845001, 0x00845803, 0x00847806, 0x00849401,
+    0x00849C01, 0x0084A401, 0x0084B801, 0x0084E802, 0x00850005,
+    0x00852804, 0x00853C01, 0x00864264, 0x00900027, 0x0091000B,
+    0x0092704E, 0x00940200, 0x009C0475, 0x009E53B9, 0x00AD400A,
+    0x00B39406, 0x00B3BC03, 0x00B3E404, 0x00B3F802, 0x00B5C001,
+    0x00B5FC01, 0x00B7804F, 0x00B8C00C, 0x00BA001A, 0x00BA6C59,
+    0x00BC00D6, 0x00BFC00C, 0x00C00005, 0x00C02019, 0x00C0A807,
+    0x00C0D802, 0x00C0F403, 0x00C26404, 0x00C28001, 0x00C3EC01,
+    0x00C64002, 0x00C6580A, 0x00C70024, 0x00C8001F, 0x00C8A81E,
+    0x00C94001, 0x00C98020, 0x00CA2827, 0x00CB003F, 0x00CC0100,
+    0x01370040, 0x02924037, 0x0293F802, 0x02983403, 0x0299BC10,
+    0x029A7C01, 0x029BC008, 0x029C0017, 0x029C8002, 0x029E2402,
+    0x02A00801, 0x02A01801, 0x02A02C01, 0x02A08C09, 0x02A0D804,
+    0x02A1D004, 0x02A20002, 0x02A2D011, 0x02A33802, 0x02A38012,
+    0x02A3E003, 0x02A4980A, 0x02A51C0D, 0x02A57C01, 0x02A60004,
+    0x02A6CC1B, 0x02A77802, 0x02A8A40E, 0x02A90C01, 0x02A93002,
+    0x02A97004, 0x02A9DC03, 0x02A9EC01, 0x02AAC001, 0x02AAC803,
+    0x02AADC02, 0x02AAF802, 0x02AB0401, 0x02AB7802, 0x02ABAC07,
+    0x02ABD402, 0x02AF8C0B, 0x03600001, 0x036DFC02, 0x036FFC02,
+    0x037FFC01, 0x03EC7801, 0x03ECA401, 0x03EEC810, 0x03F4F802,
+    0x03F7F002, 0x03F8001A, 0x03F88007, 0x03F8C023, 0x03F95013,
+    0x03F9A004, 0x03FBFC01, 0x03FC040F, 0x03FC6807, 0x03FCEC06,
+    0x03FD6C0B, 0x03FF8007, 0x03FFA007, 0x03FFE405, 0x04040003,
+    0x0404DC09, 0x0405E411, 0x0406400C, 0x0407402E, 0x040E7C01,
+    0x040F4001, 0x04215C01, 0x04247C01, 0x0424FC01, 0x04280403,
+    0x04281402, 0x04283004, 0x0428E003, 0x0428FC01, 0x04294009,
+    0x0429FC01, 0x042CE407, 0x04400003, 0x0440E016, 0x04420003,
+    0x0442C012, 0x04440003, 0x04449C0E, 0x04450004, 0x04460003,
+    0x0446CC0E, 0x04471404, 0x045AAC0D, 0x0491C004, 0x05BD442E,
+    0x05BE3C04, 0x074000F6, 0x07440027, 0x0744A4B5, 0x07480046,
+    0x074C0057, 0x075B0401, 0x075B6C01, 0x075BEC01, 0x075C5401,
+    0x075CD401, 0x075D3C01, 0x075DBC01, 0x075E2401, 0x075EA401,
+    0x075F0C01, 0x07BBC002, 0x07C0002C, 0x07C0C064, 0x07C2800F,
+    0x07C2C40E, 0x07C3040F, 0x07C3440F, 0x07C4401F, 0x07C4C03C,
+    0x07C5C02B, 0x07C7981D, 0x07C8402B, 0x07C90009, 0x07C94002,
+    0x07CC0021, 0x07CCC006, 0x07CCDC46, 0x07CE0014, 0x07CE8025,
+    0x07CF1805, 0x07CF8011, 0x07D0003F, 0x07D10001, 0x07D108B6,
+    0x07D3E404, 0x07D4003E, 0x07D50004, 0x07D54018, 0x07D7EC46,
+    0x07D9140B, 0x07DA0046, 0x07DC0074, 0x38000401, 0x38008060,
+    0x380400F0,
+  };
+  static const unsigned int aAscii[4] = {
+    0xFFFFFFFF, 0xFC00FFFF, 0xF8000001, 0xF8000001,
+  };
+
+  if( c<128 ){
+    return ( (aAscii[c >> 5] & (1 << (c & 0x001F)))==0 );
+  }else if( c<(1<<22) ){
+    unsigned int key = (((unsigned int)c)<<10) | 0x000003FF;
+    int iRes = 0;
+    int iHi = sizeof(aEntry)/sizeof(aEntry[0]) - 1;
+    int iLo = 0;
+    while( iHi>=iLo ){
+      int iTest = (iHi + iLo) / 2;
+      if( key >= aEntry[iTest] ){
+        iRes = iTest;
+        iLo = iTest+1;
+      }else{
+        iHi = iTest-1;
+      }
+    }
+    assert( aEntry[0]<key );
+    assert( key>=aEntry[iRes] );
+    return (((unsigned int)c) >= ((aEntry[iRes]>>10) + (aEntry[iRes]&0x3FF)));
+  }
+  return 1;
+}
+
+
+/*
+** If the argument is a codepoint corresponding to a lowercase letter
+** in the ASCII range with a diacritic added, return the codepoint
+** of the ASCII letter only. For example, if passed 235 - "LATIN
+** SMALL LETTER E WITH DIAERESIS" - return 65 ("LATIN SMALL LETTER
+** E"). The resuls of passing a codepoint that corresponds to an
+** uppercase letter are undefined.
+*/
+static int remove_diacritic(int c){
+  unsigned short aDia[] = {
+        0,  1797,  1848,  1859,  1891,  1928,  1940,  1995, 
+     2024,  2040,  2060,  2110,  2168,  2206,  2264,  2286, 
+     2344,  2383,  2472,  2488,  2516,  2596,  2668,  2732, 
+     2782,  2842,  2894,  2954,  2984,  3000,  3028,  3336, 
+     3456,  3696,  3712,  3728,  3744,  3896,  3912,  3928, 
+     3968,  4008,  4040,  4106,  4138,  4170,  4202,  4234, 
+     4266,  4296,  4312,  4344,  4408,  4424,  4472,  4504, 
+     6148,  6198,  6264,  6280,  6360,  6429,  6505,  6529, 
+    61448, 61468, 61534, 61592, 61642, 61688, 61704, 61726, 
+    61784, 61800, 61836, 61880, 61914, 61948, 61998, 62122, 
+    62154, 62200, 62218, 62302, 62364, 62442, 62478, 62536, 
+    62554, 62584, 62604, 62640, 62648, 62656, 62664, 62730, 
+    62924, 63050, 63082, 63274, 63390, 
+  };
+  char aChar[] = {
+    '\0', 'a',  'c',  'e',  'i',  'n',  'o',  'u',  'y',  'y',  'a',  'c',  
+    'd',  'e',  'e',  'g',  'h',  'i',  'j',  'k',  'l',  'n',  'o',  'r',  
+    's',  't',  'u',  'u',  'w',  'y',  'z',  'o',  'u',  'a',  'i',  'o',  
+    'u',  'g',  'k',  'o',  'j',  'g',  'n',  'a',  'e',  'i',  'o',  'r',  
+    'u',  's',  't',  'h',  'a',  'e',  'o',  'y',  '\0', '\0', '\0', '\0', 
+    '\0', '\0', '\0', '\0', 'a',  'b',  'd',  'd',  'e',  'f',  'g',  'h',  
+    'h',  'i',  'k',  'l',  'l',  'm',  'n',  'p',  'r',  'r',  's',  't',  
+    'u',  'v',  'w',  'w',  'x',  'y',  'z',  'h',  't',  'w',  'y',  'a',  
+    'e',  'i',  'o',  'u',  'y',  
+  };
+
+  unsigned int key = (((unsigned int)c)<<3) | 0x00000007;
+  int iRes = 0;
+  int iHi = sizeof(aDia)/sizeof(aDia[0]) - 1;
+  int iLo = 0;
+  while( iHi>=iLo ){
+    int iTest = (iHi + iLo) / 2;
+    if( key >= aDia[iTest] ){
+      iRes = iTest;
+      iLo = iTest+1;
+    }else{
+      iHi = iTest-1;
+    }
+  }
+  assert( key>=aDia[iRes] );
+  return ((c > (aDia[iRes]>>3) + (aDia[iRes]&0x07)) ? c : (int)aChar[iRes]);
+}
+
+
+/*
+** Return true if the argument interpreted as a unicode codepoint
+** is a diacritical modifier character.
+*/
+SQLITE_PRIVATE int sqlite3FtsUnicodeIsdiacritic(int c){
+  unsigned int mask0 = 0x08029FDF;
+  unsigned int mask1 = 0x000361F8;
+  if( c<768 || c>817 ) return 0;
+  return (c < 768+32) ?
+      (mask0 & (1 << (c-768))) :
+      (mask1 & (1 << (c-768-32)));
+}
+
+
+/*
+** Interpret the argument as a unicode codepoint. If the codepoint
+** is an upper case character that has a lower case equivalent,
+** return the codepoint corresponding to the lower case version.
+** Otherwise, return a copy of the argument.
+**
+** The results are undefined if the value passed to this function
+** is less than zero.
+*/
+SQLITE_PRIVATE int sqlite3FtsUnicodeFold(int c, int bRemoveDiacritic){
+  /* Each entry in the following array defines a rule for folding a range
+  ** of codepoints to lower case. The rule applies to a range of nRange
+  ** codepoints starting at codepoint iCode.
+  **
+  ** If the least significant bit in flags is clear, then the rule applies
+  ** to all nRange codepoints (i.e. all nRange codepoints are upper case and
+  ** need to be folded). Or, if it is set, then the rule only applies to
+  ** every second codepoint in the range, starting with codepoint C.
+  **
+  ** The 7 most significant bits in flags are an index into the aiOff[]
+  ** array. If a specific codepoint C does require folding, then its lower
+  ** case equivalent is ((C + aiOff[flags>>1]) & 0xFFFF).
+  **
+  ** The contents of this array are generated by parsing the CaseFolding.txt
+  ** file distributed as part of the "Unicode Character Database". See
+  ** http://www.unicode.org for details.
+  */
+  static const struct TableEntry {
+    unsigned short iCode;
+    unsigned char flags;
+    unsigned char nRange;
+  } aEntry[] = {
+    {65, 14, 26},          {181, 64, 1},          {192, 14, 23},
+    {216, 14, 7},          {256, 1, 48},          {306, 1, 6},
+    {313, 1, 16},          {330, 1, 46},          {376, 116, 1},
+    {377, 1, 6},           {383, 104, 1},         {385, 50, 1},
+    {386, 1, 4},           {390, 44, 1},          {391, 0, 1},
+    {393, 42, 2},          {395, 0, 1},           {398, 32, 1},
+    {399, 38, 1},          {400, 40, 1},          {401, 0, 1},
+    {403, 42, 1},          {404, 46, 1},          {406, 52, 1},
+    {407, 48, 1},          {408, 0, 1},           {412, 52, 1},
+    {413, 54, 1},          {415, 56, 1},          {416, 1, 6},
+    {422, 60, 1},          {423, 0, 1},           {425, 60, 1},
+    {428, 0, 1},           {430, 60, 1},          {431, 0, 1},
+    {433, 58, 2},          {435, 1, 4},           {439, 62, 1},
+    {440, 0, 1},           {444, 0, 1},           {452, 2, 1},
+    {453, 0, 1},           {455, 2, 1},           {456, 0, 1},
+    {458, 2, 1},           {459, 1, 18},          {478, 1, 18},
+    {497, 2, 1},           {498, 1, 4},           {502, 122, 1},
+    {503, 134, 1},         {504, 1, 40},          {544, 110, 1},
+    {546, 1, 18},          {570, 70, 1},          {571, 0, 1},
+    {573, 108, 1},         {574, 68, 1},          {577, 0, 1},
+    {579, 106, 1},         {580, 28, 1},          {581, 30, 1},
+    {582, 1, 10},          {837, 36, 1},          {880, 1, 4},
+    {886, 0, 1},           {902, 18, 1},          {904, 16, 3},
+    {908, 26, 1},          {910, 24, 2},          {913, 14, 17},
+    {931, 14, 9},          {962, 0, 1},           {975, 4, 1},
+    {976, 140, 1},         {977, 142, 1},         {981, 146, 1},
+    {982, 144, 1},         {984, 1, 24},          {1008, 136, 1},
+    {1009, 138, 1},        {1012, 130, 1},        {1013, 128, 1},
+    {1015, 0, 1},          {1017, 152, 1},        {1018, 0, 1},
+    {1021, 110, 3},        {1024, 34, 16},        {1040, 14, 32},
+    {1120, 1, 34},         {1162, 1, 54},         {1216, 6, 1},
+    {1217, 1, 14},         {1232, 1, 88},         {1329, 22, 38},
+    {4256, 66, 38},        {4295, 66, 1},         {4301, 66, 1},
+    {7680, 1, 150},        {7835, 132, 1},        {7838, 96, 1},
+    {7840, 1, 96},         {7944, 150, 8},        {7960, 150, 6},
+    {7976, 150, 8},        {7992, 150, 8},        {8008, 150, 6},
+    {8025, 151, 8},        {8040, 150, 8},        {8072, 150, 8},
+    {8088, 150, 8},        {8104, 150, 8},        {8120, 150, 2},
+    {8122, 126, 2},        {8124, 148, 1},        {8126, 100, 1},
+    {8136, 124, 4},        {8140, 148, 1},        {8152, 150, 2},
+    {8154, 120, 2},        {8168, 150, 2},        {8170, 118, 2},
+    {8172, 152, 1},        {8184, 112, 2},        {8186, 114, 2},
+    {8188, 148, 1},        {8486, 98, 1},         {8490, 92, 1},
+    {8491, 94, 1},         {8498, 12, 1},         {8544, 8, 16},
+    {8579, 0, 1},          {9398, 10, 26},        {11264, 22, 47},
+    {11360, 0, 1},         {11362, 88, 1},        {11363, 102, 1},
+    {11364, 90, 1},        {11367, 1, 6},         {11373, 84, 1},
+    {11374, 86, 1},        {11375, 80, 1},        {11376, 82, 1},
+    {11378, 0, 1},         {11381, 0, 1},         {11390, 78, 2},
+    {11392, 1, 100},       {11499, 1, 4},         {11506, 0, 1},
+    {42560, 1, 46},        {42624, 1, 24},        {42786, 1, 14},
+    {42802, 1, 62},        {42873, 1, 4},         {42877, 76, 1},
+    {42878, 1, 10},        {42891, 0, 1},         {42893, 74, 1},
+    {42896, 1, 4},         {42912, 1, 10},        {42922, 72, 1},
+    {65313, 14, 26},       
+  };
+  static const unsigned short aiOff[] = {
+   1,     2,     8,     15,    16,    26,    28,    32,    
+   37,    38,    40,    48,    63,    64,    69,    71,    
+   79,    80,    116,   202,   203,   205,   206,   207,   
+   209,   210,   211,   213,   214,   217,   218,   219,   
+   775,   7264,  10792, 10795, 23228, 23256, 30204, 54721, 
+   54753, 54754, 54756, 54787, 54793, 54809, 57153, 57274, 
+   57921, 58019, 58363, 61722, 65268, 65341, 65373, 65406, 
+   65408, 65410, 65415, 65424, 65436, 65439, 65450, 65462, 
+   65472, 65476, 65478, 65480, 65482, 65488, 65506, 65511, 
+   65514, 65521, 65527, 65528, 65529, 
+  };
+
+  int ret = c;
+
+  assert( c>=0 );
+  assert( sizeof(unsigned short)==2 && sizeof(unsigned char)==1 );
+
+  if( c<128 ){
+    if( c>='A' && c<='Z' ) ret = c + ('a' - 'A');
+  }else if( c<65536 ){
+    int iHi = sizeof(aEntry)/sizeof(aEntry[0]) - 1;
+    int iLo = 0;
+    int iRes = -1;
+
+    while( iHi>=iLo ){
+      int iTest = (iHi + iLo) / 2;
+      int cmp = (c - aEntry[iTest].iCode);
+      if( cmp>=0 ){
+        iRes = iTest;
+        iLo = iTest+1;
+      }else{
+        iHi = iTest-1;
+      }
+    }
+    assert( iRes<0 || c>=aEntry[iRes].iCode );
+
+    if( iRes>=0 ){
+      const struct TableEntry *p = &aEntry[iRes];
+      if( c<(p->iCode + p->nRange) && 0==(0x01 & p->flags & (p->iCode ^ c)) ){
+        ret = (c + (aiOff[p->flags>>1])) & 0x0000FFFF;
+        assert( ret>0 );
+      }
+    }
+
+    if( bRemoveDiacritic ) ret = remove_diacritic(ret);
+  }
+  
+  else if( c>=66560 && c<66600 ){
+    ret = c + 40;
+  }
+
+  return ret;
+}
+#endif /* defined(SQLITE_ENABLE_FTS3) || defined(SQLITE_ENABLE_FTS4) */
+#endif /* !defined(SQLITE_DISABLE_FTS3_UNICODE) */
+
+/************** End of fts3_unicode2.c ***************************************/
+/************** Begin file rtree.c *******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains code for implementations of the r-tree and r*-tree
+** algorithms packaged as an SQLite virtual table module.
+*/
+
+/*
+** Database Format of R-Tree Tables
+** --------------------------------
+**
+** The data structure for a single virtual r-tree table is stored in three 
+** native SQLite tables declared as follows. In each case, the '%' character
+** in the table name is replaced with the user-supplied name of the r-tree
+** table.
+**
+**   CREATE TABLE %_node(nodeno INTEGER PRIMARY KEY, data BLOB)
+**   CREATE TABLE %_parent(nodeno INTEGER PRIMARY KEY, parentnode INTEGER)
+**   CREATE TABLE %_rowid(rowid INTEGER PRIMARY KEY, nodeno INTEGER)
+**
+** The data for each node of the r-tree structure is stored in the %_node
+** table. For each node that is not the root node of the r-tree, there is
+** an entry in the %_parent table associating the node with its parent.
+** And for each row of data in the table, there is an entry in the %_rowid
+** table that maps from the entries rowid to the id of the node that it
+** is stored on.
+**
+** The root node of an r-tree always exists, even if the r-tree table is
+** empty. The nodeno of the root node is always 1. All other nodes in the
+** table must be the same size as the root node. The content of each node
+** is formatted as follows:
+**
+**   1. If the node is the root node (node 1), then the first 2 bytes
+**      of the node contain the tree depth as a big-endian integer.
+**      For non-root nodes, the first 2 bytes are left unused.
+**
+**   2. The next 2 bytes contain the number of entries currently 
+**      stored in the node.
+**
+**   3. The remainder of the node contains the node entries. Each entry
+**      consists of a single 8-byte integer followed by an even number
+**      of 4-byte coordinates. For leaf nodes the integer is the rowid
+**      of a record. For internal nodes it is the node number of a
+**      child page.
+*/
+
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_RTREE)
+
+#ifndef SQLITE_CORE
+/*   #include "sqlite3ext.h" */
+  SQLITE_EXTENSION_INIT1
+#else
+/*   #include "sqlite3.h" */
+#endif
+
+/* #include <string.h> */
+/* #include <assert.h> */
+/* #include <stdio.h> */
+
+#ifndef SQLITE_AMALGAMATION
+#include "sqlite3rtree.h"
+typedef sqlite3_int64 i64;
+typedef unsigned char u8;
+typedef unsigned short u16;
+typedef unsigned int u32;
+#endif
+
+/*  The following macro is used to suppress compiler warnings.
+*/
+#ifndef UNUSED_PARAMETER
+# define UNUSED_PARAMETER(x) (void)(x)
+#endif
+
+typedef struct Rtree Rtree;
+typedef struct RtreeCursor RtreeCursor;
+typedef struct RtreeNode RtreeNode;
+typedef struct RtreeCell RtreeCell;
+typedef struct RtreeConstraint RtreeConstraint;
+typedef struct RtreeMatchArg RtreeMatchArg;
+typedef struct RtreeGeomCallback RtreeGeomCallback;
+typedef union RtreeCoord RtreeCoord;
+typedef struct RtreeSearchPoint RtreeSearchPoint;
+
+/* The rtree may have between 1 and RTREE_MAX_DIMENSIONS dimensions. */
+#define RTREE_MAX_DIMENSIONS 5
+
+/* Size of hash table Rtree.aHash. This hash table is not expected to
+** ever contain very many entries, so a fixed number of buckets is 
+** used.
+*/
+#define HASHSIZE 97
+
+/* The xBestIndex method of this virtual table requires an estimate of
+** the number of rows in the virtual table to calculate the costs of
+** various strategies. If possible, this estimate is loaded from the
+** sqlite_stat1 table (with RTREE_MIN_ROWEST as a hard-coded minimum).
+** Otherwise, if no sqlite_stat1 entry is available, use 
+** RTREE_DEFAULT_ROWEST.
+*/
+#define RTREE_DEFAULT_ROWEST 1048576
+#define RTREE_MIN_ROWEST         100
+
+/* 
+** An rtree virtual-table object.
+*/
+struct Rtree {
+  sqlite3_vtab base;          /* Base class.  Must be first */
+  sqlite3 *db;                /* Host database connection */
+  int iNodeSize;              /* Size in bytes of each node in the node table */
+  u8 nDim;                    /* Number of dimensions */
+  u8 eCoordType;              /* RTREE_COORD_REAL32 or RTREE_COORD_INT32 */
+  u8 nBytesPerCell;           /* Bytes consumed per cell */
+  int iDepth;                 /* Current depth of the r-tree structure */
+  char *zDb;                  /* Name of database containing r-tree table */
+  char *zName;                /* Name of r-tree table */ 
+  int nBusy;                  /* Current number of users of this structure */
+  i64 nRowEst;                /* Estimated number of rows in this table */
+
+  /* List of nodes removed during a CondenseTree operation. List is
+  ** linked together via the pointer normally used for hash chains -
+  ** RtreeNode.pNext. RtreeNode.iNode stores the depth of the sub-tree 
+  ** headed by the node (leaf nodes have RtreeNode.iNode==0).
+  */
+  RtreeNode *pDeleted;
+  int iReinsertHeight;        /* Height of sub-trees Reinsert() has run on */
+
+  /* Statements to read/write/delete a record from xxx_node */
+  sqlite3_stmt *pReadNode;
+  sqlite3_stmt *pWriteNode;
+  sqlite3_stmt *pDeleteNode;
+
+  /* Statements to read/write/delete a record from xxx_rowid */
+  sqlite3_stmt *pReadRowid;
+  sqlite3_stmt *pWriteRowid;
+  sqlite3_stmt *pDeleteRowid;
+
+  /* Statements to read/write/delete a record from xxx_parent */
+  sqlite3_stmt *pReadParent;
+  sqlite3_stmt *pWriteParent;
+  sqlite3_stmt *pDeleteParent;
+
+  RtreeNode *aHash[HASHSIZE]; /* Hash table of in-memory nodes. */ 
+};
+
+/* Possible values for Rtree.eCoordType: */
+#define RTREE_COORD_REAL32 0
+#define RTREE_COORD_INT32  1
+
+/*
+** If SQLITE_RTREE_INT_ONLY is defined, then this virtual table will
+** only deal with integer coordinates.  No floating point operations
+** will be done.
+*/
+#ifdef SQLITE_RTREE_INT_ONLY
+  typedef sqlite3_int64 RtreeDValue;       /* High accuracy coordinate */
+  typedef int RtreeValue;                  /* Low accuracy coordinate */
+# define RTREE_ZERO 0
+#else
+  typedef double RtreeDValue;              /* High accuracy coordinate */
+  typedef float RtreeValue;                /* Low accuracy coordinate */
+# define RTREE_ZERO 0.0
+#endif
+
+/*
+** When doing a search of an r-tree, instances of the following structure
+** record intermediate results from the tree walk.
+**
+** The id is always a node-id.  For iLevel>=1 the id is the node-id of
+** the node that the RtreeSearchPoint represents.  When iLevel==0, however,
+** the id is of the parent node and the cell that RtreeSearchPoint
+** represents is the iCell-th entry in the parent node.
+*/
+struct RtreeSearchPoint {
+  RtreeDValue rScore;    /* The score for this node.  Smallest goes first. */
+  sqlite3_int64 id;      /* Node ID */
+  u8 iLevel;             /* 0=entries.  1=leaf node.  2+ for higher */
+  u8 eWithin;            /* PARTLY_WITHIN or FULLY_WITHIN */
+  u8 iCell;              /* Cell index within the node */
+};
+
+/*
+** The minimum number of cells allowed for a node is a third of the 
+** maximum. In Gutman's notation:
+**
+**     m = M/3
+**
+** If an R*-tree "Reinsert" operation is required, the same number of
+** cells are removed from the overfull node and reinserted into the tree.
+*/
+#define RTREE_MINCELLS(p) ((((p)->iNodeSize-4)/(p)->nBytesPerCell)/3)
+#define RTREE_REINSERT(p) RTREE_MINCELLS(p)
+#define RTREE_MAXCELLS 51
+
+/*
+** The smallest possible node-size is (512-64)==448 bytes. And the largest
+** supported cell size is 48 bytes (8 byte rowid + ten 4 byte coordinates).
+** Therefore all non-root nodes must contain at least 3 entries. Since 
+** 2^40 is greater than 2^64, an r-tree structure always has a depth of
+** 40 or less.
+*/
+#define RTREE_MAX_DEPTH 40
+
+
+/*
+** Number of entries in the cursor RtreeNode cache.  The first entry is
+** used to cache the RtreeNode for RtreeCursor.sPoint.  The remaining
+** entries cache the RtreeNode for the first elements of the priority queue.
+*/
+#define RTREE_CACHE_SZ  5
+
+/* 
+** An rtree cursor object.
+*/
+struct RtreeCursor {
+  sqlite3_vtab_cursor base;         /* Base class.  Must be first */
+  u8 atEOF;                         /* True if at end of search */
+  u8 bPoint;                        /* True if sPoint is valid */
+  int iStrategy;                    /* Copy of idxNum search parameter */
+  int nConstraint;                  /* Number of entries in aConstraint */
+  RtreeConstraint *aConstraint;     /* Search constraints. */
+  int nPointAlloc;                  /* Number of slots allocated for aPoint[] */
+  int nPoint;                       /* Number of slots used in aPoint[] */
+  int mxLevel;                      /* iLevel value for root of the tree */
+  RtreeSearchPoint *aPoint;         /* Priority queue for search points */
+  RtreeSearchPoint sPoint;          /* Cached next search point */
+  RtreeNode *aNode[RTREE_CACHE_SZ]; /* Rtree node cache */
+  u32 anQueue[RTREE_MAX_DEPTH+1];   /* Number of queued entries by iLevel */
+};
+
+/* Return the Rtree of a RtreeCursor */
+#define RTREE_OF_CURSOR(X)   ((Rtree*)((X)->base.pVtab))
+
+/*
+** A coordinate can be either a floating point number or a integer.  All
+** coordinates within a single R-Tree are always of the same time.
+*/
+union RtreeCoord {
+  RtreeValue f;      /* Floating point value */
+  int i;             /* Integer value */
+  u32 u;             /* Unsigned for byte-order conversions */
+};
+
+/*
+** The argument is an RtreeCoord. Return the value stored within the RtreeCoord
+** formatted as a RtreeDValue (double or int64). This macro assumes that local
+** variable pRtree points to the Rtree structure associated with the
+** RtreeCoord.
+*/
+#ifdef SQLITE_RTREE_INT_ONLY
+# define DCOORD(coord) ((RtreeDValue)coord.i)
+#else
+# define DCOORD(coord) (                           \
+    (pRtree->eCoordType==RTREE_COORD_REAL32) ?      \
+      ((double)coord.f) :                           \
+      ((double)coord.i)                             \
+  )
+#endif
+
+/*
+** A search constraint.
+*/
+struct RtreeConstraint {
+  int iCoord;                     /* Index of constrained coordinate */
+  int op;                         /* Constraining operation */
+  union {
+    RtreeDValue rValue;             /* Constraint value. */
+    int (*xGeom)(sqlite3_rtree_geometry*,int,RtreeDValue*,int*);
+    int (*xQueryFunc)(sqlite3_rtree_query_info*);
+  } u;
+  sqlite3_rtree_query_info *pInfo;  /* xGeom and xQueryFunc argument */
+};
+
+/* Possible values for RtreeConstraint.op */
+#define RTREE_EQ    0x41  /* A */
+#define RTREE_LE    0x42  /* B */
+#define RTREE_LT    0x43  /* C */
+#define RTREE_GE    0x44  /* D */
+#define RTREE_GT    0x45  /* E */
+#define RTREE_MATCH 0x46  /* F: Old-style sqlite3_rtree_geometry_callback() */
+#define RTREE_QUERY 0x47  /* G: New-style sqlite3_rtree_query_callback() */
+
+
+/* 
+** An rtree structure node.
+*/
+struct RtreeNode {
+  RtreeNode *pParent;         /* Parent node */
+  i64 iNode;                  /* The node number */
+  int nRef;                   /* Number of references to this node */
+  int isDirty;                /* True if the node needs to be written to disk */
+  u8 *zData;                  /* Content of the node, as should be on disk */
+  RtreeNode *pNext;           /* Next node in this hash collision chain */
+};
+
+/* Return the number of cells in a node  */
+#define NCELL(pNode) readInt16(&(pNode)->zData[2])
+
+/* 
+** A single cell from a node, deserialized
+*/
+struct RtreeCell {
+  i64 iRowid;                                 /* Node or entry ID */
+  RtreeCoord aCoord[RTREE_MAX_DIMENSIONS*2];  /* Bounding box coordinates */
+};
+
+
+/*
+** This object becomes the sqlite3_user_data() for the SQL functions
+** that are created by sqlite3_rtree_geometry_callback() and
+** sqlite3_rtree_query_callback() and which appear on the right of MATCH
+** operators in order to constrain a search.
+**
+** xGeom and xQueryFunc are the callback functions.  Exactly one of 
+** xGeom and xQueryFunc fields is non-NULL, depending on whether the
+** SQL function was created using sqlite3_rtree_geometry_callback() or
+** sqlite3_rtree_query_callback().
+** 
+** This object is deleted automatically by the destructor mechanism in
+** sqlite3_create_function_v2().
+*/
+struct RtreeGeomCallback {
+  int (*xGeom)(sqlite3_rtree_geometry*, int, RtreeDValue*, int*);
+  int (*xQueryFunc)(sqlite3_rtree_query_info*);
+  void (*xDestructor)(void*);
+  void *pContext;
+};
+
+
+/*
+** Value for the first field of every RtreeMatchArg object. The MATCH
+** operator tests that the first field of a blob operand matches this
+** value to avoid operating on invalid blobs (which could cause a segfault).
+*/
+#define RTREE_GEOMETRY_MAGIC 0x891245AB
+
+/*
+** An instance of this structure (in the form of a BLOB) is returned by
+** the SQL functions that sqlite3_rtree_geometry_callback() and
+** sqlite3_rtree_query_callback() create, and is read as the right-hand
+** operand to the MATCH operator of an R-Tree.
+*/
+struct RtreeMatchArg {
+  u32 magic;                  /* Always RTREE_GEOMETRY_MAGIC */
+  RtreeGeomCallback cb;       /* Info about the callback functions */
+  int nParam;                 /* Number of parameters to the SQL function */
+  sqlite3_value **apSqlParam; /* Original SQL parameter values */
+  RtreeDValue aParam[1];      /* Values for parameters to the SQL function */
+};
+
+#ifndef MAX
+# define MAX(x,y) ((x) < (y) ? (y) : (x))
+#endif
+#ifndef MIN
+# define MIN(x,y) ((x) > (y) ? (y) : (x))
+#endif
+
+/*
+** Functions to deserialize a 16 bit integer, 32 bit real number and
+** 64 bit integer. The deserialized value is returned.
+*/
+static int readInt16(u8 *p){
+  return (p[0]<<8) + p[1];
+}
+static void readCoord(u8 *p, RtreeCoord *pCoord){
+  pCoord->u = (
+    (((u32)p[0]) << 24) + 
+    (((u32)p[1]) << 16) + 
+    (((u32)p[2]) <<  8) + 
+    (((u32)p[3]) <<  0)
+  );
+}
+static i64 readInt64(u8 *p){
+  return (
+    (((i64)p[0]) << 56) + 
+    (((i64)p[1]) << 48) + 
+    (((i64)p[2]) << 40) + 
+    (((i64)p[3]) << 32) + 
+    (((i64)p[4]) << 24) + 
+    (((i64)p[5]) << 16) + 
+    (((i64)p[6]) <<  8) + 
+    (((i64)p[7]) <<  0)
+  );
+}
+
+/*
+** Functions to serialize a 16 bit integer, 32 bit real number and
+** 64 bit integer. The value returned is the number of bytes written
+** to the argument buffer (always 2, 4 and 8 respectively).
+*/
+static int writeInt16(u8 *p, int i){
+  p[0] = (i>> 8)&0xFF;
+  p[1] = (i>> 0)&0xFF;
+  return 2;
+}
+static int writeCoord(u8 *p, RtreeCoord *pCoord){
+  u32 i;
+  assert( sizeof(RtreeCoord)==4 );
+  assert( sizeof(u32)==4 );
+  i = pCoord->u;
+  p[0] = (i>>24)&0xFF;
+  p[1] = (i>>16)&0xFF;
+  p[2] = (i>> 8)&0xFF;
+  p[3] = (i>> 0)&0xFF;
+  return 4;
+}
+static int writeInt64(u8 *p, i64 i){
+  p[0] = (i>>56)&0xFF;
+  p[1] = (i>>48)&0xFF;
+  p[2] = (i>>40)&0xFF;
+  p[3] = (i>>32)&0xFF;
+  p[4] = (i>>24)&0xFF;
+  p[5] = (i>>16)&0xFF;
+  p[6] = (i>> 8)&0xFF;
+  p[7] = (i>> 0)&0xFF;
+  return 8;
+}
+
+/*
+** Increment the reference count of node p.
+*/
+static void nodeReference(RtreeNode *p){
+  if( p ){
+    p->nRef++;
+  }
+}
+
+/*
+** Clear the content of node p (set all bytes to 0x00).
+*/
+static void nodeZero(Rtree *pRtree, RtreeNode *p){
+  memset(&p->zData[2], 0, pRtree->iNodeSize-2);
+  p->isDirty = 1;
+}
+
+/*
+** Given a node number iNode, return the corresponding key to use
+** in the Rtree.aHash table.
+*/
+static int nodeHash(i64 iNode){
+  return iNode % HASHSIZE;
+}
+
+/*
+** Search the node hash table for node iNode. If found, return a pointer
+** to it. Otherwise, return 0.
+*/
+static RtreeNode *nodeHashLookup(Rtree *pRtree, i64 iNode){
+  RtreeNode *p;
+  for(p=pRtree->aHash[nodeHash(iNode)]; p && p->iNode!=iNode; p=p->pNext);
+  return p;
+}
+
+/*
+** Add node pNode to the node hash table.
+*/
+static void nodeHashInsert(Rtree *pRtree, RtreeNode *pNode){
+  int iHash;
+  assert( pNode->pNext==0 );
+  iHash = nodeHash(pNode->iNode);
+  pNode->pNext = pRtree->aHash[iHash];
+  pRtree->aHash[iHash] = pNode;
+}
+
+/*
+** Remove node pNode from the node hash table.
+*/
+static void nodeHashDelete(Rtree *pRtree, RtreeNode *pNode){
+  RtreeNode **pp;
+  if( pNode->iNode!=0 ){
+    pp = &pRtree->aHash[nodeHash(pNode->iNode)];
+    for( ; (*pp)!=pNode; pp = &(*pp)->pNext){ assert(*pp); }
+    *pp = pNode->pNext;
+    pNode->pNext = 0;
+  }
+}
+
+/*
+** Allocate and return new r-tree node. Initially, (RtreeNode.iNode==0),
+** indicating that node has not yet been assigned a node number. It is
+** assigned a node number when nodeWrite() is called to write the
+** node contents out to the database.
+*/
+static RtreeNode *nodeNew(Rtree *pRtree, RtreeNode *pParent){
+  RtreeNode *pNode;
+  pNode = (RtreeNode *)sqlite3_malloc(sizeof(RtreeNode) + pRtree->iNodeSize);
+  if( pNode ){
+    memset(pNode, 0, sizeof(RtreeNode) + pRtree->iNodeSize);
+    pNode->zData = (u8 *)&pNode[1];
+    pNode->nRef = 1;
+    pNode->pParent = pParent;
+    pNode->isDirty = 1;
+    nodeReference(pParent);
+  }
+  return pNode;
+}
+
+/*
+** Obtain a reference to an r-tree node.
+*/
+static int nodeAcquire(
+  Rtree *pRtree,             /* R-tree structure */
+  i64 iNode,                 /* Node number to load */
+  RtreeNode *pParent,        /* Either the parent node or NULL */
+  RtreeNode **ppNode         /* OUT: Acquired node */
+){
+  int rc;
+  int rc2 = SQLITE_OK;
+  RtreeNode *pNode;
+
+  /* Check if the requested node is already in the hash table. If so,
+  ** increase its reference count and return it.
+  */
+  if( (pNode = nodeHashLookup(pRtree, iNode)) ){
+    assert( !pParent || !pNode->pParent || pNode->pParent==pParent );
+    if( pParent && !pNode->pParent ){
+      nodeReference(pParent);
+      pNode->pParent = pParent;
+    }
+    pNode->nRef++;
+    *ppNode = pNode;
+    return SQLITE_OK;
+  }
+
+  sqlite3_bind_int64(pRtree->pReadNode, 1, iNode);
+  rc = sqlite3_step(pRtree->pReadNode);
+  if( rc==SQLITE_ROW ){
+    const u8 *zBlob = sqlite3_column_blob(pRtree->pReadNode, 0);
+    if( pRtree->iNodeSize==sqlite3_column_bytes(pRtree->pReadNode, 0) ){
+      pNode = (RtreeNode *)sqlite3_malloc(sizeof(RtreeNode)+pRtree->iNodeSize);
+      if( !pNode ){
+        rc2 = SQLITE_NOMEM;
+      }else{
+        pNode->pParent = pParent;
+        pNode->zData = (u8 *)&pNode[1];
+        pNode->nRef = 1;
+        pNode->iNode = iNode;
+        pNode->isDirty = 0;
+        pNode->pNext = 0;
+        memcpy(pNode->zData, zBlob, pRtree->iNodeSize);
+        nodeReference(pParent);
+      }
+    }
+  }
+  rc = sqlite3_reset(pRtree->pReadNode);
+  if( rc==SQLITE_OK ) rc = rc2;
+
+  /* If the root node was just loaded, set pRtree->iDepth to the height
+  ** of the r-tree structure. A height of zero means all data is stored on
+  ** the root node. A height of one means the children of the root node
+  ** are the leaves, and so on. If the depth as specified on the root node
+  ** is greater than RTREE_MAX_DEPTH, the r-tree structure must be corrupt.
+  */
+  if( pNode && iNode==1 ){
+    pRtree->iDepth = readInt16(pNode->zData);
+    if( pRtree->iDepth>RTREE_MAX_DEPTH ){
+      rc = SQLITE_CORRUPT_VTAB;
+    }
+  }
+
+  /* If no error has occurred so far, check if the "number of entries"
+  ** field on the node is too large. If so, set the return code to 
+  ** SQLITE_CORRUPT_VTAB.
+  */
+  if( pNode && rc==SQLITE_OK ){
+    if( NCELL(pNode)>((pRtree->iNodeSize-4)/pRtree->nBytesPerCell) ){
+      rc = SQLITE_CORRUPT_VTAB;
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    if( pNode!=0 ){
+      nodeHashInsert(pRtree, pNode);
+    }else{
+      rc = SQLITE_CORRUPT_VTAB;
+    }
+    *ppNode = pNode;
+  }else{
+    sqlite3_free(pNode);
+    *ppNode = 0;
+  }
+
+  return rc;
+}
+
+/*
+** Overwrite cell iCell of node pNode with the contents of pCell.
+*/
+static void nodeOverwriteCell(
+  Rtree *pRtree,             /* The overall R-Tree */
+  RtreeNode *pNode,          /* The node into which the cell is to be written */
+  RtreeCell *pCell,          /* The cell to write */
+  int iCell                  /* Index into pNode into which pCell is written */
+){
+  int ii;
+  u8 *p = &pNode->zData[4 + pRtree->nBytesPerCell*iCell];
+  p += writeInt64(p, pCell->iRowid);
+  for(ii=0; ii<(pRtree->nDim*2); ii++){
+    p += writeCoord(p, &pCell->aCoord[ii]);
+  }
+  pNode->isDirty = 1;
+}
+
+/*
+** Remove the cell with index iCell from node pNode.
+*/
+static void nodeDeleteCell(Rtree *pRtree, RtreeNode *pNode, int iCell){
+  u8 *pDst = &pNode->zData[4 + pRtree->nBytesPerCell*iCell];
+  u8 *pSrc = &pDst[pRtree->nBytesPerCell];
+  int nByte = (NCELL(pNode) - iCell - 1) * pRtree->nBytesPerCell;
+  memmove(pDst, pSrc, nByte);
+  writeInt16(&pNode->zData[2], NCELL(pNode)-1);
+  pNode->isDirty = 1;
+}
+
+/*
+** Insert the contents of cell pCell into node pNode. If the insert
+** is successful, return SQLITE_OK.
+**
+** If there is not enough free space in pNode, return SQLITE_FULL.
+*/
+static int nodeInsertCell(
+  Rtree *pRtree,                /* The overall R-Tree */
+  RtreeNode *pNode,             /* Write new cell into this node */
+  RtreeCell *pCell              /* The cell to be inserted */
+){
+  int nCell;                    /* Current number of cells in pNode */
+  int nMaxCell;                 /* Maximum number of cells for pNode */
+
+  nMaxCell = (pRtree->iNodeSize-4)/pRtree->nBytesPerCell;
+  nCell = NCELL(pNode);
+
+  assert( nCell<=nMaxCell );
+  if( nCell<nMaxCell ){
+    nodeOverwriteCell(pRtree, pNode, pCell, nCell);
+    writeInt16(&pNode->zData[2], nCell+1);
+    pNode->isDirty = 1;
+  }
+
+  return (nCell==nMaxCell);
+}
+
+/*
+** If the node is dirty, write it out to the database.
+*/
+static int nodeWrite(Rtree *pRtree, RtreeNode *pNode){
+  int rc = SQLITE_OK;
+  if( pNode->isDirty ){
+    sqlite3_stmt *p = pRtree->pWriteNode;
+    if( pNode->iNode ){
+      sqlite3_bind_int64(p, 1, pNode->iNode);
+    }else{
+      sqlite3_bind_null(p, 1);
+    }
+    sqlite3_bind_blob(p, 2, pNode->zData, pRtree->iNodeSize, SQLITE_STATIC);
+    sqlite3_step(p);
+    pNode->isDirty = 0;
+    rc = sqlite3_reset(p);
+    if( pNode->iNode==0 && rc==SQLITE_OK ){
+      pNode->iNode = sqlite3_last_insert_rowid(pRtree->db);
+      nodeHashInsert(pRtree, pNode);
+    }
+  }
+  return rc;
+}
+
+/*
+** Release a reference to a node. If the node is dirty and the reference
+** count drops to zero, the node data is written to the database.
+*/
+static int nodeRelease(Rtree *pRtree, RtreeNode *pNode){
+  int rc = SQLITE_OK;
+  if( pNode ){
+    assert( pNode->nRef>0 );
+    pNode->nRef--;
+    if( pNode->nRef==0 ){
+      if( pNode->iNode==1 ){
+        pRtree->iDepth = -1;
+      }
+      if( pNode->pParent ){
+        rc = nodeRelease(pRtree, pNode->pParent);
+      }
+      if( rc==SQLITE_OK ){
+        rc = nodeWrite(pRtree, pNode);
+      }
+      nodeHashDelete(pRtree, pNode);
+      sqlite3_free(pNode);
+    }
+  }
+  return rc;
+}
+
+/*
+** Return the 64-bit integer value associated with cell iCell of
+** node pNode. If pNode is a leaf node, this is a rowid. If it is
+** an internal node, then the 64-bit integer is a child page number.
+*/
+static i64 nodeGetRowid(
+  Rtree *pRtree,       /* The overall R-Tree */
+  RtreeNode *pNode,    /* The node from which to extract the ID */
+  int iCell            /* The cell index from which to extract the ID */
+){
+  assert( iCell<NCELL(pNode) );
+  return readInt64(&pNode->zData[4 + pRtree->nBytesPerCell*iCell]);
+}
+
+/*
+** Return coordinate iCoord from cell iCell in node pNode.
+*/
+static void nodeGetCoord(
+  Rtree *pRtree,               /* The overall R-Tree */
+  RtreeNode *pNode,            /* The node from which to extract a coordinate */
+  int iCell,                   /* The index of the cell within the node */
+  int iCoord,                  /* Which coordinate to extract */
+  RtreeCoord *pCoord           /* OUT: Space to write result to */
+){
+  readCoord(&pNode->zData[12 + pRtree->nBytesPerCell*iCell + 4*iCoord], pCoord);
+}
+
+/*
+** Deserialize cell iCell of node pNode. Populate the structure pointed
+** to by pCell with the results.
+*/
+static void nodeGetCell(
+  Rtree *pRtree,               /* The overall R-Tree */
+  RtreeNode *pNode,            /* The node containing the cell to be read */
+  int iCell,                   /* Index of the cell within the node */
+  RtreeCell *pCell             /* OUT: Write the cell contents here */
+){
+  u8 *pData;
+  RtreeCoord *pCoord;
+  int ii;
+  pCell->iRowid = nodeGetRowid(pRtree, pNode, iCell);
+  pData = pNode->zData + (12 + pRtree->nBytesPerCell*iCell);
+  pCoord = pCell->aCoord;
+  for(ii=0; ii<pRtree->nDim*2; ii++){
+    readCoord(&pData[ii*4], &pCoord[ii]);
+  }
+}
+
+
+/* Forward declaration for the function that does the work of
+** the virtual table module xCreate() and xConnect() methods.
+*/
+static int rtreeInit(
+  sqlite3 *, void *, int, const char *const*, sqlite3_vtab **, char **, int
+);
+
+/* 
+** Rtree virtual table module xCreate method.
+*/
+static int rtreeCreate(
+  sqlite3 *db,
+  void *pAux,
+  int argc, const char *const*argv,
+  sqlite3_vtab **ppVtab,
+  char **pzErr
+){
+  return rtreeInit(db, pAux, argc, argv, ppVtab, pzErr, 1);
+}
+
+/* 
+** Rtree virtual table module xConnect method.
+*/
+static int rtreeConnect(
+  sqlite3 *db,
+  void *pAux,
+  int argc, const char *const*argv,
+  sqlite3_vtab **ppVtab,
+  char **pzErr
+){
+  return rtreeInit(db, pAux, argc, argv, ppVtab, pzErr, 0);
+}
+
+/*
+** Increment the r-tree reference count.
+*/
+static void rtreeReference(Rtree *pRtree){
+  pRtree->nBusy++;
+}
+
+/*
+** Decrement the r-tree reference count. When the reference count reaches
+** zero the structure is deleted.
+*/
+static void rtreeRelease(Rtree *pRtree){
+  pRtree->nBusy--;
+  if( pRtree->nBusy==0 ){
+    sqlite3_finalize(pRtree->pReadNode);
+    sqlite3_finalize(pRtree->pWriteNode);
+    sqlite3_finalize(pRtree->pDeleteNode);
+    sqlite3_finalize(pRtree->pReadRowid);
+    sqlite3_finalize(pRtree->pWriteRowid);
+    sqlite3_finalize(pRtree->pDeleteRowid);
+    sqlite3_finalize(pRtree->pReadParent);
+    sqlite3_finalize(pRtree->pWriteParent);
+    sqlite3_finalize(pRtree->pDeleteParent);
+    sqlite3_free(pRtree);
+  }
+}
+
+/* 
+** Rtree virtual table module xDisconnect method.
+*/
+static int rtreeDisconnect(sqlite3_vtab *pVtab){
+  rtreeRelease((Rtree *)pVtab);
+  return SQLITE_OK;
+}
+
+/* 
+** Rtree virtual table module xDestroy method.
+*/
+static int rtreeDestroy(sqlite3_vtab *pVtab){
+  Rtree *pRtree = (Rtree *)pVtab;
+  int rc;
+  char *zCreate = sqlite3_mprintf(
+    "DROP TABLE '%q'.'%q_node';"
+    "DROP TABLE '%q'.'%q_rowid';"
+    "DROP TABLE '%q'.'%q_parent';",
+    pRtree->zDb, pRtree->zName, 
+    pRtree->zDb, pRtree->zName,
+    pRtree->zDb, pRtree->zName
+  );
+  if( !zCreate ){
+    rc = SQLITE_NOMEM;
+  }else{
+    rc = sqlite3_exec(pRtree->db, zCreate, 0, 0, 0);
+    sqlite3_free(zCreate);
+  }
+  if( rc==SQLITE_OK ){
+    rtreeRelease(pRtree);
+  }
+
+  return rc;
+}
+
+/* 
+** Rtree virtual table module xOpen method.
+*/
+static int rtreeOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){
+  int rc = SQLITE_NOMEM;
+  RtreeCursor *pCsr;
+
+  pCsr = (RtreeCursor *)sqlite3_malloc(sizeof(RtreeCursor));
+  if( pCsr ){
+    memset(pCsr, 0, sizeof(RtreeCursor));
+    pCsr->base.pVtab = pVTab;
+    rc = SQLITE_OK;
+  }
+  *ppCursor = (sqlite3_vtab_cursor *)pCsr;
+
+  return rc;
+}
+
+
+/*
+** Free the RtreeCursor.aConstraint[] array and its contents.
+*/
+static void freeCursorConstraints(RtreeCursor *pCsr){
+  if( pCsr->aConstraint ){
+    int i;                        /* Used to iterate through constraint array */
+    for(i=0; i<pCsr->nConstraint; i++){
+      sqlite3_rtree_query_info *pInfo = pCsr->aConstraint[i].pInfo;
+      if( pInfo ){
+        if( pInfo->xDelUser ) pInfo->xDelUser(pInfo->pUser);
+        sqlite3_free(pInfo);
+      }
+    }
+    sqlite3_free(pCsr->aConstraint);
+    pCsr->aConstraint = 0;
+  }
+}
+
+/* 
+** Rtree virtual table module xClose method.
+*/
+static int rtreeClose(sqlite3_vtab_cursor *cur){
+  Rtree *pRtree = (Rtree *)(cur->pVtab);
+  int ii;
+  RtreeCursor *pCsr = (RtreeCursor *)cur;
+  freeCursorConstraints(pCsr);
+  sqlite3_free(pCsr->aPoint);
+  for(ii=0; ii<RTREE_CACHE_SZ; ii++) nodeRelease(pRtree, pCsr->aNode[ii]);
+  sqlite3_free(pCsr);
+  return SQLITE_OK;
+}
+
+/*
+** Rtree virtual table module xEof method.
+**
+** Return non-zero if the cursor does not currently point to a valid 
+** record (i.e if the scan has finished), or zero otherwise.
+*/
+static int rtreeEof(sqlite3_vtab_cursor *cur){
+  RtreeCursor *pCsr = (RtreeCursor *)cur;
+  return pCsr->atEOF;
+}
+
+/*
+** Convert raw bits from the on-disk RTree record into a coordinate value.
+** The on-disk format is big-endian and needs to be converted for little-
+** endian platforms.  The on-disk record stores integer coordinates if
+** eInt is true and it stores 32-bit floating point records if eInt is
+** false.  a[] is the four bytes of the on-disk record to be decoded.
+** Store the results in "r".
+**
+** There are three versions of this macro, one each for little-endian and
+** big-endian processors and a third generic implementation.  The endian-
+** specific implementations are much faster and are preferred if the
+** processor endianness is known at compile-time.  The SQLITE_BYTEORDER
+** macro is part of sqliteInt.h and hence the endian-specific
+** implementation will only be used if this module is compiled as part
+** of the amalgamation.
+*/
+#if defined(SQLITE_BYTEORDER) && SQLITE_BYTEORDER==1234
+#define RTREE_DECODE_COORD(eInt, a, r) {                        \
+    RtreeCoord c;    /* Coordinate decoded */                   \
+    memcpy(&c.u,a,4);                                           \
+    c.u = ((c.u>>24)&0xff)|((c.u>>8)&0xff00)|                   \
+          ((c.u&0xff)<<24)|((c.u&0xff00)<<8);                   \
+    r = eInt ? (sqlite3_rtree_dbl)c.i : (sqlite3_rtree_dbl)c.f; \
+}
+#elif defined(SQLITE_BYTEORDER) && SQLITE_BYTEORDER==4321
+#define RTREE_DECODE_COORD(eInt, a, r) {                        \
+    RtreeCoord c;    /* Coordinate decoded */                   \
+    memcpy(&c.u,a,4);                                           \
+    r = eInt ? (sqlite3_rtree_dbl)c.i : (sqlite3_rtree_dbl)c.f; \
+}
+#else
+#define RTREE_DECODE_COORD(eInt, a, r) {                        \
+    RtreeCoord c;    /* Coordinate decoded */                   \
+    c.u = ((u32)a[0]<<24) + ((u32)a[1]<<16)                     \
+           +((u32)a[2]<<8) + a[3];                              \
+    r = eInt ? (sqlite3_rtree_dbl)c.i : (sqlite3_rtree_dbl)c.f; \
+}
+#endif
+
+/*
+** Check the RTree node or entry given by pCellData and p against the MATCH
+** constraint pConstraint.  
+*/
+static int rtreeCallbackConstraint(
+  RtreeConstraint *pConstraint,  /* The constraint to test */
+  int eInt,                      /* True if RTree holding integer coordinates */
+  u8 *pCellData,                 /* Raw cell content */
+  RtreeSearchPoint *pSearch,     /* Container of this cell */
+  sqlite3_rtree_dbl *prScore,    /* OUT: score for the cell */
+  int *peWithin                  /* OUT: visibility of the cell */
+){
+  int i;                                                /* Loop counter */
+  sqlite3_rtree_query_info *pInfo = pConstraint->pInfo; /* Callback info */
+  int nCoord = pInfo->nCoord;                           /* No. of coordinates */
+  int rc;                                             /* Callback return code */
+  sqlite3_rtree_dbl aCoord[RTREE_MAX_DIMENSIONS*2];   /* Decoded coordinates */
+
+  assert( pConstraint->op==RTREE_MATCH || pConstraint->op==RTREE_QUERY );
+  assert( nCoord==2 || nCoord==4 || nCoord==6 || nCoord==8 || nCoord==10 );
+
+  if( pConstraint->op==RTREE_QUERY && pSearch->iLevel==1 ){
+    pInfo->iRowid = readInt64(pCellData);
+  }
+  pCellData += 8;
+  for(i=0; i<nCoord; i++, pCellData += 4){
+    RTREE_DECODE_COORD(eInt, pCellData, aCoord[i]);
+  }
+  if( pConstraint->op==RTREE_MATCH ){
+    rc = pConstraint->u.xGeom((sqlite3_rtree_geometry*)pInfo,
+                              nCoord, aCoord, &i);
+    if( i==0 ) *peWithin = NOT_WITHIN;
+    *prScore = RTREE_ZERO;
+  }else{
+    pInfo->aCoord = aCoord;
+    pInfo->iLevel = pSearch->iLevel - 1;
+    pInfo->rScore = pInfo->rParentScore = pSearch->rScore;
+    pInfo->eWithin = pInfo->eParentWithin = pSearch->eWithin;
+    rc = pConstraint->u.xQueryFunc(pInfo);
+    if( pInfo->eWithin<*peWithin ) *peWithin = pInfo->eWithin;
+    if( pInfo->rScore<*prScore || *prScore<RTREE_ZERO ){
+      *prScore = pInfo->rScore;
+    }
+  }
+  return rc;
+}
+
+/* 
+** Check the internal RTree node given by pCellData against constraint p.
+** If this constraint cannot be satisfied by any child within the node,
+** set *peWithin to NOT_WITHIN.
+*/
+static void rtreeNonleafConstraint(
+  RtreeConstraint *p,        /* The constraint to test */
+  int eInt,                  /* True if RTree holds integer coordinates */
+  u8 *pCellData,             /* Raw cell content as appears on disk */
+  int *peWithin              /* Adjust downward, as appropriate */
+){
+  sqlite3_rtree_dbl val;     /* Coordinate value convert to a double */
+
+  /* p->iCoord might point to either a lower or upper bound coordinate
+  ** in a coordinate pair.  But make pCellData point to the lower bound.
+  */
+  pCellData += 8 + 4*(p->iCoord&0xfe);
+
+  assert(p->op==RTREE_LE || p->op==RTREE_LT || p->op==RTREE_GE 
+      || p->op==RTREE_GT || p->op==RTREE_EQ );
+  switch( p->op ){
+    case RTREE_LE:
+    case RTREE_LT:
+    case RTREE_EQ:
+      RTREE_DECODE_COORD(eInt, pCellData, val);
+      /* val now holds the lower bound of the coordinate pair */
+      if( p->u.rValue>=val ) return;
+      if( p->op!=RTREE_EQ ) break;  /* RTREE_LE and RTREE_LT end here */
+      /* Fall through for the RTREE_EQ case */
+
+    default: /* RTREE_GT or RTREE_GE,  or fallthrough of RTREE_EQ */
+      pCellData += 4;
+      RTREE_DECODE_COORD(eInt, pCellData, val);
+      /* val now holds the upper bound of the coordinate pair */
+      if( p->u.rValue<=val ) return;
+  }
+  *peWithin = NOT_WITHIN;
+}
+
+/*
+** Check the leaf RTree cell given by pCellData against constraint p.
+** If this constraint is not satisfied, set *peWithin to NOT_WITHIN.
+** If the constraint is satisfied, leave *peWithin unchanged.
+**
+** The constraint is of the form:  xN op $val
+**
+** The op is given by p->op.  The xN is p->iCoord-th coordinate in
+** pCellData.  $val is given by p->u.rValue.
+*/
+static void rtreeLeafConstraint(
+  RtreeConstraint *p,        /* The constraint to test */
+  int eInt,                  /* True if RTree holds integer coordinates */
+  u8 *pCellData,             /* Raw cell content as appears on disk */
+  int *peWithin              /* Adjust downward, as appropriate */
+){
+  RtreeDValue xN;      /* Coordinate value converted to a double */
+
+  assert(p->op==RTREE_LE || p->op==RTREE_LT || p->op==RTREE_GE 
+      || p->op==RTREE_GT || p->op==RTREE_EQ );
+  pCellData += 8 + p->iCoord*4;
+  RTREE_DECODE_COORD(eInt, pCellData, xN);
+  switch( p->op ){
+    case RTREE_LE: if( xN <= p->u.rValue ) return;  break;
+    case RTREE_LT: if( xN <  p->u.rValue ) return;  break;
+    case RTREE_GE: if( xN >= p->u.rValue ) return;  break;
+    case RTREE_GT: if( xN >  p->u.rValue ) return;  break;
+    default:       if( xN == p->u.rValue ) return;  break;
+  }
+  *peWithin = NOT_WITHIN;
+}
+
+/*
+** One of the cells in node pNode is guaranteed to have a 64-bit 
+** integer value equal to iRowid. Return the index of this cell.
+*/
+static int nodeRowidIndex(
+  Rtree *pRtree, 
+  RtreeNode *pNode, 
+  i64 iRowid,
+  int *piIndex
+){
+  int ii;
+  int nCell = NCELL(pNode);
+  assert( nCell<200 );
+  for(ii=0; ii<nCell; ii++){
+    if( nodeGetRowid(pRtree, pNode, ii)==iRowid ){
+      *piIndex = ii;
+      return SQLITE_OK;
+    }
+  }
+  return SQLITE_CORRUPT_VTAB;
+}
+
+/*
+** Return the index of the cell containing a pointer to node pNode
+** in its parent. If pNode is the root node, return -1.
+*/
+static int nodeParentIndex(Rtree *pRtree, RtreeNode *pNode, int *piIndex){
+  RtreeNode *pParent = pNode->pParent;
+  if( pParent ){
+    return nodeRowidIndex(pRtree, pParent, pNode->iNode, piIndex);
+  }
+  *piIndex = -1;
+  return SQLITE_OK;
+}
+
+/*
+** Compare two search points.  Return negative, zero, or positive if the first
+** is less than, equal to, or greater than the second.
+**
+** The rScore is the primary key.  Smaller rScore values come first.
+** If the rScore is a tie, then use iLevel as the tie breaker with smaller
+** iLevel values coming first.  In this way, if rScore is the same for all
+** SearchPoints, then iLevel becomes the deciding factor and the result
+** is a depth-first search, which is the desired default behavior.
+*/
+static int rtreeSearchPointCompare(
+  const RtreeSearchPoint *pA,
+  const RtreeSearchPoint *pB
+){
+  if( pA->rScore<pB->rScore ) return -1;
+  if( pA->rScore>pB->rScore ) return +1;
+  if( pA->iLevel<pB->iLevel ) return -1;
+  if( pA->iLevel>pB->iLevel ) return +1;
+  return 0;
+}
+
+/*
+** Interchange to search points in a cursor.
+*/
+static void rtreeSearchPointSwap(RtreeCursor *p, int i, int j){
+  RtreeSearchPoint t = p->aPoint[i];
+  assert( i<j );
+  p->aPoint[i] = p->aPoint[j];
+  p->aPoint[j] = t;
+  i++; j++;
+  if( i<RTREE_CACHE_SZ ){
+    if( j>=RTREE_CACHE_SZ ){
+      nodeRelease(RTREE_OF_CURSOR(p), p->aNode[i]);
+      p->aNode[i] = 0;
+    }else{
+      RtreeNode *pTemp = p->aNode[i];
+      p->aNode[i] = p->aNode[j];
+      p->aNode[j] = pTemp;
+    }
+  }
+}
+
+/*
+** Return the search point with the lowest current score.
+*/
+static RtreeSearchPoint *rtreeSearchPointFirst(RtreeCursor *pCur){
+  return pCur->bPoint ? &pCur->sPoint : pCur->nPoint ? pCur->aPoint : 0;
+}
+
+/*
+** Get the RtreeNode for the search point with the lowest score.
+*/
+static RtreeNode *rtreeNodeOfFirstSearchPoint(RtreeCursor *pCur, int *pRC){
+  sqlite3_int64 id;
+  int ii = 1 - pCur->bPoint;
+  assert( ii==0 || ii==1 );
+  assert( pCur->bPoint || pCur->nPoint );
+  if( pCur->aNode[ii]==0 ){
+    assert( pRC!=0 );
+    id = ii ? pCur->aPoint[0].id : pCur->sPoint.id;
+    *pRC = nodeAcquire(RTREE_OF_CURSOR(pCur), id, 0, &pCur->aNode[ii]);
+  }
+  return pCur->aNode[ii];
+}
+
+/*
+** Push a new element onto the priority queue
+*/
+static RtreeSearchPoint *rtreeEnqueue(
+  RtreeCursor *pCur,    /* The cursor */
+  RtreeDValue rScore,   /* Score for the new search point */
+  u8 iLevel             /* Level for the new search point */
+){
+  int i, j;
+  RtreeSearchPoint *pNew;
+  if( pCur->nPoint>=pCur->nPointAlloc ){
+    int nNew = pCur->nPointAlloc*2 + 8;
+    pNew = sqlite3_realloc(pCur->aPoint, nNew*sizeof(pCur->aPoint[0]));
+    if( pNew==0 ) return 0;
+    pCur->aPoint = pNew;
+    pCur->nPointAlloc = nNew;
+  }
+  i = pCur->nPoint++;
+  pNew = pCur->aPoint + i;
+  pNew->rScore = rScore;
+  pNew->iLevel = iLevel;
+  assert( iLevel<=RTREE_MAX_DEPTH );
+  while( i>0 ){
+    RtreeSearchPoint *pParent;
+    j = (i-1)/2;
+    pParent = pCur->aPoint + j;
+    if( rtreeSearchPointCompare(pNew, pParent)>=0 ) break;
+    rtreeSearchPointSwap(pCur, j, i);
+    i = j;
+    pNew = pParent;
+  }
+  return pNew;
+}
+
+/*
+** Allocate a new RtreeSearchPoint and return a pointer to it.  Return
+** NULL if malloc fails.
+*/
+static RtreeSearchPoint *rtreeSearchPointNew(
+  RtreeCursor *pCur,    /* The cursor */
+  RtreeDValue rScore,   /* Score for the new search point */
+  u8 iLevel             /* Level for the new search point */
+){
+  RtreeSearchPoint *pNew, *pFirst;
+  pFirst = rtreeSearchPointFirst(pCur);
+  pCur->anQueue[iLevel]++;
+  if( pFirst==0
+   || pFirst->rScore>rScore 
+   || (pFirst->rScore==rScore && pFirst->iLevel>iLevel)
+  ){
+    if( pCur->bPoint ){
+      int ii;
+      pNew = rtreeEnqueue(pCur, rScore, iLevel);
+      if( pNew==0 ) return 0;
+      ii = (int)(pNew - pCur->aPoint) + 1;
+      if( ii<RTREE_CACHE_SZ ){
+        assert( pCur->aNode[ii]==0 );
+        pCur->aNode[ii] = pCur->aNode[0];
+       }else{
+        nodeRelease(RTREE_OF_CURSOR(pCur), pCur->aNode[0]);
+      }
+      pCur->aNode[0] = 0;
+      *pNew = pCur->sPoint;
+    }
+    pCur->sPoint.rScore = rScore;
+    pCur->sPoint.iLevel = iLevel;
+    pCur->bPoint = 1;
+    return &pCur->sPoint;
+  }else{
+    return rtreeEnqueue(pCur, rScore, iLevel);
+  }
+}
+
+#if 0
+/* Tracing routines for the RtreeSearchPoint queue */
+static void tracePoint(RtreeSearchPoint *p, int idx, RtreeCursor *pCur){
+  if( idx<0 ){ printf(" s"); }else{ printf("%2d", idx); }
+  printf(" %d.%05lld.%02d %g %d",
+    p->iLevel, p->id, p->iCell, p->rScore, p->eWithin
+  );
+  idx++;
+  if( idx<RTREE_CACHE_SZ ){
+    printf(" %p\n", pCur->aNode[idx]);
+  }else{
+    printf("\n");
+  }
+}
+static void traceQueue(RtreeCursor *pCur, const char *zPrefix){
+  int ii;
+  printf("=== %9s ", zPrefix);
+  if( pCur->bPoint ){
+    tracePoint(&pCur->sPoint, -1, pCur);
+  }
+  for(ii=0; ii<pCur->nPoint; ii++){
+    if( ii>0 || pCur->bPoint ) printf("              ");
+    tracePoint(&pCur->aPoint[ii], ii, pCur);
+  }
+}
+# define RTREE_QUEUE_TRACE(A,B) traceQueue(A,B)
+#else
+# define RTREE_QUEUE_TRACE(A,B)   /* no-op */
+#endif
+
+/* Remove the search point with the lowest current score.
+*/
+static void rtreeSearchPointPop(RtreeCursor *p){
+  int i, j, k, n;
+  i = 1 - p->bPoint;
+  assert( i==0 || i==1 );
+  if( p->aNode[i] ){
+    nodeRelease(RTREE_OF_CURSOR(p), p->aNode[i]);
+    p->aNode[i] = 0;
+  }
+  if( p->bPoint ){
+    p->anQueue[p->sPoint.iLevel]--;
+    p->bPoint = 0;
+  }else if( p->nPoint ){
+    p->anQueue[p->aPoint[0].iLevel]--;
+    n = --p->nPoint;
+    p->aPoint[0] = p->aPoint[n];
+    if( n<RTREE_CACHE_SZ-1 ){
+      p->aNode[1] = p->aNode[n+1];
+      p->aNode[n+1] = 0;
+    }
+    i = 0;
+    while( (j = i*2+1)<n ){
+      k = j+1;
+      if( k<n && rtreeSearchPointCompare(&p->aPoint[k], &p->aPoint[j])<0 ){
+        if( rtreeSearchPointCompare(&p->aPoint[k], &p->aPoint[i])<0 ){
+          rtreeSearchPointSwap(p, i, k);
+          i = k;
+        }else{
+          break;
+        }
+      }else{
+        if( rtreeSearchPointCompare(&p->aPoint[j], &p->aPoint[i])<0 ){
+          rtreeSearchPointSwap(p, i, j);
+          i = j;
+        }else{
+          break;
+        }
+      }
+    }
+  }
+}
+
+
+/*
+** Continue the search on cursor pCur until the front of the queue
+** contains an entry suitable for returning as a result-set row,
+** or until the RtreeSearchPoint queue is empty, indicating that the
+** query has completed.
+*/
+static int rtreeStepToLeaf(RtreeCursor *pCur){
+  RtreeSearchPoint *p;
+  Rtree *pRtree = RTREE_OF_CURSOR(pCur);
+  RtreeNode *pNode;
+  int eWithin;
+  int rc = SQLITE_OK;
+  int nCell;
+  int nConstraint = pCur->nConstraint;
+  int ii;
+  int eInt;
+  RtreeSearchPoint x;
+
+  eInt = pRtree->eCoordType==RTREE_COORD_INT32;
+  while( (p = rtreeSearchPointFirst(pCur))!=0 && p->iLevel>0 ){
+    pNode = rtreeNodeOfFirstSearchPoint(pCur, &rc);
+    if( rc ) return rc;
+    nCell = NCELL(pNode);
+    assert( nCell<200 );
+    while( p->iCell<nCell ){
+      sqlite3_rtree_dbl rScore = (sqlite3_rtree_dbl)-1;
+      u8 *pCellData = pNode->zData + (4+pRtree->nBytesPerCell*p->iCell);
+      eWithin = FULLY_WITHIN;
+      for(ii=0; ii<nConstraint; ii++){
+        RtreeConstraint *pConstraint = pCur->aConstraint + ii;
+        if( pConstraint->op>=RTREE_MATCH ){
+          rc = rtreeCallbackConstraint(pConstraint, eInt, pCellData, p,
+                                       &rScore, &eWithin);
+          if( rc ) return rc;
+        }else if( p->iLevel==1 ){
+          rtreeLeafConstraint(pConstraint, eInt, pCellData, &eWithin);
+        }else{
+          rtreeNonleafConstraint(pConstraint, eInt, pCellData, &eWithin);
+        }
+        if( eWithin==NOT_WITHIN ) break;
+      }
+      p->iCell++;
+      if( eWithin==NOT_WITHIN ) continue;
+      x.iLevel = p->iLevel - 1;
+      if( x.iLevel ){
+        x.id = readInt64(pCellData);
+        x.iCell = 0;
+      }else{
+        x.id = p->id;
+        x.iCell = p->iCell - 1;
+      }
+      if( p->iCell>=nCell ){
+        RTREE_QUEUE_TRACE(pCur, "POP-S:");
+        rtreeSearchPointPop(pCur);
+      }
+      if( rScore<RTREE_ZERO ) rScore = RTREE_ZERO;
+      p = rtreeSearchPointNew(pCur, rScore, x.iLevel);
+      if( p==0 ) return SQLITE_NOMEM;
+      p->eWithin = eWithin;
+      p->id = x.id;
+      p->iCell = x.iCell;
+      RTREE_QUEUE_TRACE(pCur, "PUSH-S:");
+      break;
+    }
+    if( p->iCell>=nCell ){
+      RTREE_QUEUE_TRACE(pCur, "POP-Se:");
+      rtreeSearchPointPop(pCur);
+    }
+  }
+  pCur->atEOF = p==0;
+  return SQLITE_OK;
+}
+
+/* 
+** Rtree virtual table module xNext method.
+*/
+static int rtreeNext(sqlite3_vtab_cursor *pVtabCursor){
+  RtreeCursor *pCsr = (RtreeCursor *)pVtabCursor;
+  int rc = SQLITE_OK;
+
+  /* Move to the next entry that matches the configured constraints. */
+  RTREE_QUEUE_TRACE(pCsr, "POP-Nx:");
+  rtreeSearchPointPop(pCsr);
+  rc = rtreeStepToLeaf(pCsr);
+  return rc;
+}
+
+/* 
+** Rtree virtual table module xRowid method.
+*/
+static int rtreeRowid(sqlite3_vtab_cursor *pVtabCursor, sqlite_int64 *pRowid){
+  RtreeCursor *pCsr = (RtreeCursor *)pVtabCursor;
+  RtreeSearchPoint *p = rtreeSearchPointFirst(pCsr);
+  int rc = SQLITE_OK;
+  RtreeNode *pNode = rtreeNodeOfFirstSearchPoint(pCsr, &rc);
+  if( rc==SQLITE_OK && p ){
+    *pRowid = nodeGetRowid(RTREE_OF_CURSOR(pCsr), pNode, p->iCell);
+  }
+  return rc;
+}
+
+/* 
+** Rtree virtual table module xColumn method.
+*/
+static int rtreeColumn(sqlite3_vtab_cursor *cur, sqlite3_context *ctx, int i){
+  Rtree *pRtree = (Rtree *)cur->pVtab;
+  RtreeCursor *pCsr = (RtreeCursor *)cur;
+  RtreeSearchPoint *p = rtreeSearchPointFirst(pCsr);
+  RtreeCoord c;
+  int rc = SQLITE_OK;
+  RtreeNode *pNode = rtreeNodeOfFirstSearchPoint(pCsr, &rc);
+
+  if( rc ) return rc;
+  if( p==0 ) return SQLITE_OK;
+  if( i==0 ){
+    sqlite3_result_int64(ctx, nodeGetRowid(pRtree, pNode, p->iCell));
+  }else{
+    if( rc ) return rc;
+    nodeGetCoord(pRtree, pNode, p->iCell, i-1, &c);
+#ifndef SQLITE_RTREE_INT_ONLY
+    if( pRtree->eCoordType==RTREE_COORD_REAL32 ){
+      sqlite3_result_double(ctx, c.f);
+    }else
+#endif
+    {
+      assert( pRtree->eCoordType==RTREE_COORD_INT32 );
+      sqlite3_result_int(ctx, c.i);
+    }
+  }
+  return SQLITE_OK;
+}
+
+/* 
+** Use nodeAcquire() to obtain the leaf node containing the record with 
+** rowid iRowid. If successful, set *ppLeaf to point to the node and
+** return SQLITE_OK. If there is no such record in the table, set
+** *ppLeaf to 0 and return SQLITE_OK. If an error occurs, set *ppLeaf
+** to zero and return an SQLite error code.
+*/
+static int findLeafNode(
+  Rtree *pRtree,              /* RTree to search */
+  i64 iRowid,                 /* The rowid searching for */
+  RtreeNode **ppLeaf,         /* Write the node here */
+  sqlite3_int64 *piNode       /* Write the node-id here */
+){
+  int rc;
+  *ppLeaf = 0;
+  sqlite3_bind_int64(pRtree->pReadRowid, 1, iRowid);
+  if( sqlite3_step(pRtree->pReadRowid)==SQLITE_ROW ){
+    i64 iNode = sqlite3_column_int64(pRtree->pReadRowid, 0);
+    if( piNode ) *piNode = iNode;
+    rc = nodeAcquire(pRtree, iNode, 0, ppLeaf);
+    sqlite3_reset(pRtree->pReadRowid);
+  }else{
+    rc = sqlite3_reset(pRtree->pReadRowid);
+  }
+  return rc;
+}
+
+/*
+** This function is called to configure the RtreeConstraint object passed
+** as the second argument for a MATCH constraint. The value passed as the
+** first argument to this function is the right-hand operand to the MATCH
+** operator.
+*/
+static int deserializeGeometry(sqlite3_value *pValue, RtreeConstraint *pCons){
+  RtreeMatchArg *pBlob;              /* BLOB returned by geometry function */
+  sqlite3_rtree_query_info *pInfo;   /* Callback information */
+  int nBlob;                         /* Size of the geometry function blob */
+  int nExpected;                     /* Expected size of the BLOB */
+
+  /* Check that value is actually a blob. */
+  if( sqlite3_value_type(pValue)!=SQLITE_BLOB ) return SQLITE_ERROR;
+
+  /* Check that the blob is roughly the right size. */
+  nBlob = sqlite3_value_bytes(pValue);
+  if( nBlob<(int)sizeof(RtreeMatchArg) ){
+    return SQLITE_ERROR;
+  }
+
+  pInfo = (sqlite3_rtree_query_info*)sqlite3_malloc( sizeof(*pInfo)+nBlob );
+  if( !pInfo ) return SQLITE_NOMEM;
+  memset(pInfo, 0, sizeof(*pInfo));
+  pBlob = (RtreeMatchArg*)&pInfo[1];
+
+  memcpy(pBlob, sqlite3_value_blob(pValue), nBlob);
+  nExpected = (int)(sizeof(RtreeMatchArg) +
+                    pBlob->nParam*sizeof(sqlite3_value*) +
+                    (pBlob->nParam-1)*sizeof(RtreeDValue));
+  if( pBlob->magic!=RTREE_GEOMETRY_MAGIC || nBlob!=nExpected ){
+    sqlite3_free(pInfo);
+    return SQLITE_ERROR;
+  }
+  pInfo->pContext = pBlob->cb.pContext;
+  pInfo->nParam = pBlob->nParam;
+  pInfo->aParam = pBlob->aParam;
+  pInfo->apSqlParam = pBlob->apSqlParam;
+
+  if( pBlob->cb.xGeom ){
+    pCons->u.xGeom = pBlob->cb.xGeom;
+  }else{
+    pCons->op = RTREE_QUERY;
+    pCons->u.xQueryFunc = pBlob->cb.xQueryFunc;
+  }
+  pCons->pInfo = pInfo;
+  return SQLITE_OK;
+}
+
+/* 
+** Rtree virtual table module xFilter method.
+*/
+static int rtreeFilter(
+  sqlite3_vtab_cursor *pVtabCursor, 
+  int idxNum, const char *idxStr,
+  int argc, sqlite3_value **argv
+){
+  Rtree *pRtree = (Rtree *)pVtabCursor->pVtab;
+  RtreeCursor *pCsr = (RtreeCursor *)pVtabCursor;
+  RtreeNode *pRoot = 0;
+  int ii;
+  int rc = SQLITE_OK;
+  int iCell = 0;
+
+  rtreeReference(pRtree);
+
+  /* Reset the cursor to the same state as rtreeOpen() leaves it in. */
+  freeCursorConstraints(pCsr);
+  sqlite3_free(pCsr->aPoint);
+  memset(pCsr, 0, sizeof(RtreeCursor));
+  pCsr->base.pVtab = (sqlite3_vtab*)pRtree;
+
+  pCsr->iStrategy = idxNum;
+  if( idxNum==1 ){
+    /* Special case - lookup by rowid. */
+    RtreeNode *pLeaf;        /* Leaf on which the required cell resides */
+    RtreeSearchPoint *p;     /* Search point for the leaf */
+    i64 iRowid = sqlite3_value_int64(argv[0]);
+    i64 iNode = 0;
+    rc = findLeafNode(pRtree, iRowid, &pLeaf, &iNode);
+    if( rc==SQLITE_OK && pLeaf!=0 ){
+      p = rtreeSearchPointNew(pCsr, RTREE_ZERO, 0);
+      assert( p!=0 );  /* Always returns pCsr->sPoint */
+      pCsr->aNode[0] = pLeaf;
+      p->id = iNode;
+      p->eWithin = PARTLY_WITHIN;
+      rc = nodeRowidIndex(pRtree, pLeaf, iRowid, &iCell);
+      p->iCell = iCell;
+      RTREE_QUEUE_TRACE(pCsr, "PUSH-F1:");
+    }else{
+      pCsr->atEOF = 1;
+    }
+  }else{
+    /* Normal case - r-tree scan. Set up the RtreeCursor.aConstraint array 
+    ** with the configured constraints. 
+    */
+    rc = nodeAcquire(pRtree, 1, 0, &pRoot);
+    if( rc==SQLITE_OK && argc>0 ){
+      pCsr->aConstraint = sqlite3_malloc(sizeof(RtreeConstraint)*argc);
+      pCsr->nConstraint = argc;
+      if( !pCsr->aConstraint ){
+        rc = SQLITE_NOMEM;
+      }else{
+        memset(pCsr->aConstraint, 0, sizeof(RtreeConstraint)*argc);
+        memset(pCsr->anQueue, 0, sizeof(u32)*(pRtree->iDepth + 1));
+        assert( (idxStr==0 && argc==0)
+                || (idxStr && (int)strlen(idxStr)==argc*2) );
+        for(ii=0; ii<argc; ii++){
+          RtreeConstraint *p = &pCsr->aConstraint[ii];
+          p->op = idxStr[ii*2];
+          p->iCoord = idxStr[ii*2+1]-'0';
+          if( p->op>=RTREE_MATCH ){
+            /* A MATCH operator. The right-hand-side must be a blob that
+            ** can be cast into an RtreeMatchArg object. One created using
+            ** an sqlite3_rtree_geometry_callback() SQL user function.
+            */
+            rc = deserializeGeometry(argv[ii], p);
+            if( rc!=SQLITE_OK ){
+              break;
+            }
+            p->pInfo->nCoord = pRtree->nDim*2;
+            p->pInfo->anQueue = pCsr->anQueue;
+            p->pInfo->mxLevel = pRtree->iDepth + 1;
+          }else{
+#ifdef SQLITE_RTREE_INT_ONLY
+            p->u.rValue = sqlite3_value_int64(argv[ii]);
+#else
+            p->u.rValue = sqlite3_value_double(argv[ii]);
+#endif
+          }
+        }
+      }
+    }
+    if( rc==SQLITE_OK ){
+      RtreeSearchPoint *pNew;
+      pNew = rtreeSearchPointNew(pCsr, RTREE_ZERO, pRtree->iDepth+1);
+      if( pNew==0 ) return SQLITE_NOMEM;
+      pNew->id = 1;
+      pNew->iCell = 0;
+      pNew->eWithin = PARTLY_WITHIN;
+      assert( pCsr->bPoint==1 );
+      pCsr->aNode[0] = pRoot;
+      pRoot = 0;
+      RTREE_QUEUE_TRACE(pCsr, "PUSH-Fm:");
+      rc = rtreeStepToLeaf(pCsr);
+    }
+  }
+
+  nodeRelease(pRtree, pRoot);
+  rtreeRelease(pRtree);
+  return rc;
+}
+
+/*
+** Set the pIdxInfo->estimatedRows variable to nRow. Unless this
+** extension is currently being used by a version of SQLite too old to
+** support estimatedRows. In that case this function is a no-op.
+*/
+static void setEstimatedRows(sqlite3_index_info *pIdxInfo, i64 nRow){
+#if SQLITE_VERSION_NUMBER>=3008002
+  if( sqlite3_libversion_number()>=3008002 ){
+    pIdxInfo->estimatedRows = nRow;
+  }
+#endif
+}
+
+/*
+** Rtree virtual table module xBestIndex method. There are three
+** table scan strategies to choose from (in order from most to 
+** least desirable):
+**
+**   idxNum     idxStr        Strategy
+**   ------------------------------------------------
+**     1        Unused        Direct lookup by rowid.
+**     2        See below     R-tree query or full-table scan.
+**   ------------------------------------------------
+**
+** If strategy 1 is used, then idxStr is not meaningful. If strategy
+** 2 is used, idxStr is formatted to contain 2 bytes for each 
+** constraint used. The first two bytes of idxStr correspond to 
+** the constraint in sqlite3_index_info.aConstraintUsage[] with
+** (argvIndex==1) etc.
+**
+** The first of each pair of bytes in idxStr identifies the constraint
+** operator as follows:
+**
+**   Operator    Byte Value
+**   ----------------------
+**      =        0x41 ('A')
+**     <=        0x42 ('B')
+**      <        0x43 ('C')
+**     >=        0x44 ('D')
+**      >        0x45 ('E')
+**   MATCH       0x46 ('F')
+**   ----------------------
+**
+** The second of each pair of bytes identifies the coordinate column
+** to which the constraint applies. The leftmost coordinate column
+** is 'a', the second from the left 'b' etc.
+*/
+static int rtreeBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
+  Rtree *pRtree = (Rtree*)tab;
+  int rc = SQLITE_OK;
+  int ii;
+  int bMatch = 0;                 /* True if there exists a MATCH constraint */
+  i64 nRow;                       /* Estimated rows returned by this scan */
+
+  int iIdx = 0;
+  char zIdxStr[RTREE_MAX_DIMENSIONS*8+1];
+  memset(zIdxStr, 0, sizeof(zIdxStr));
+
+  /* Check if there exists a MATCH constraint - even an unusable one. If there
+  ** is, do not consider the lookup-by-rowid plan as using such a plan would
+  ** require the VDBE to evaluate the MATCH constraint, which is not currently
+  ** possible. */
+  for(ii=0; ii<pIdxInfo->nConstraint; ii++){
+    if( pIdxInfo->aConstraint[ii].op==SQLITE_INDEX_CONSTRAINT_MATCH ){
+      bMatch = 1;
+    }
+  }
+
+  assert( pIdxInfo->idxStr==0 );
+  for(ii=0; ii<pIdxInfo->nConstraint && iIdx<(int)(sizeof(zIdxStr)-1); ii++){
+    struct sqlite3_index_constraint *p = &pIdxInfo->aConstraint[ii];
+
+    if( bMatch==0 && p->usable 
+     && p->iColumn==0 && p->op==SQLITE_INDEX_CONSTRAINT_EQ 
+    ){
+      /* We have an equality constraint on the rowid. Use strategy 1. */
+      int jj;
+      for(jj=0; jj<ii; jj++){
+        pIdxInfo->aConstraintUsage[jj].argvIndex = 0;
+        pIdxInfo->aConstraintUsage[jj].omit = 0;
+      }
+      pIdxInfo->idxNum = 1;
+      pIdxInfo->aConstraintUsage[ii].argvIndex = 1;
+      pIdxInfo->aConstraintUsage[jj].omit = 1;
+
+      /* This strategy involves a two rowid lookups on an B-Tree structures
+      ** and then a linear search of an R-Tree node. This should be 
+      ** considered almost as quick as a direct rowid lookup (for which 
+      ** sqlite uses an internal cost of 0.0). It is expected to return
+      ** a single row.
+      */ 
+      pIdxInfo->estimatedCost = 30.0;
+      setEstimatedRows(pIdxInfo, 1);
+      return SQLITE_OK;
+    }
+
+    if( p->usable && (p->iColumn>0 || p->op==SQLITE_INDEX_CONSTRAINT_MATCH) ){
+      u8 op;
+      switch( p->op ){
+        case SQLITE_INDEX_CONSTRAINT_EQ: op = RTREE_EQ; break;
+        case SQLITE_INDEX_CONSTRAINT_GT: op = RTREE_GT; break;
+        case SQLITE_INDEX_CONSTRAINT_LE: op = RTREE_LE; break;
+        case SQLITE_INDEX_CONSTRAINT_LT: op = RTREE_LT; break;
+        case SQLITE_INDEX_CONSTRAINT_GE: op = RTREE_GE; break;
+        default:
+          assert( p->op==SQLITE_INDEX_CONSTRAINT_MATCH );
+          op = RTREE_MATCH; 
+          break;
+      }
+      zIdxStr[iIdx++] = op;
+      zIdxStr[iIdx++] = p->iColumn - 1 + '0';
+      pIdxInfo->aConstraintUsage[ii].argvIndex = (iIdx/2);
+      pIdxInfo->aConstraintUsage[ii].omit = 1;
+    }
+  }
+
+  pIdxInfo->idxNum = 2;
+  pIdxInfo->needToFreeIdxStr = 1;
+  if( iIdx>0 && 0==(pIdxInfo->idxStr = sqlite3_mprintf("%s", zIdxStr)) ){
+    return SQLITE_NOMEM;
+  }
+
+  nRow = pRtree->nRowEst >> (iIdx/2);
+  pIdxInfo->estimatedCost = (double)6.0 * (double)nRow;
+  setEstimatedRows(pIdxInfo, nRow);
+
+  return rc;
+}
+
+/*
+** Return the N-dimensional volumn of the cell stored in *p.
+*/
+static RtreeDValue cellArea(Rtree *pRtree, RtreeCell *p){
+  RtreeDValue area = (RtreeDValue)1;
+  int ii;
+  for(ii=0; ii<(pRtree->nDim*2); ii+=2){
+    area = (area * (DCOORD(p->aCoord[ii+1]) - DCOORD(p->aCoord[ii])));
+  }
+  return area;
+}
+
+/*
+** Return the margin length of cell p. The margin length is the sum
+** of the objects size in each dimension.
+*/
+static RtreeDValue cellMargin(Rtree *pRtree, RtreeCell *p){
+  RtreeDValue margin = (RtreeDValue)0;
+  int ii;
+  for(ii=0; ii<(pRtree->nDim*2); ii+=2){
+    margin += (DCOORD(p->aCoord[ii+1]) - DCOORD(p->aCoord[ii]));
+  }
+  return margin;
+}
+
+/*
+** Store the union of cells p1 and p2 in p1.
+*/
+static void cellUnion(Rtree *pRtree, RtreeCell *p1, RtreeCell *p2){
+  int ii;
+  if( pRtree->eCoordType==RTREE_COORD_REAL32 ){
+    for(ii=0; ii<(pRtree->nDim*2); ii+=2){
+      p1->aCoord[ii].f = MIN(p1->aCoord[ii].f, p2->aCoord[ii].f);
+      p1->aCoord[ii+1].f = MAX(p1->aCoord[ii+1].f, p2->aCoord[ii+1].f);
+    }
+  }else{
+    for(ii=0; ii<(pRtree->nDim*2); ii+=2){
+      p1->aCoord[ii].i = MIN(p1->aCoord[ii].i, p2->aCoord[ii].i);
+      p1->aCoord[ii+1].i = MAX(p1->aCoord[ii+1].i, p2->aCoord[ii+1].i);
+    }
+  }
+}
+
+/*
+** Return true if the area covered by p2 is a subset of the area covered
+** by p1. False otherwise.
+*/
+static int cellContains(Rtree *pRtree, RtreeCell *p1, RtreeCell *p2){
+  int ii;
+  int isInt = (pRtree->eCoordType==RTREE_COORD_INT32);
+  for(ii=0; ii<(pRtree->nDim*2); ii+=2){
+    RtreeCoord *a1 = &p1->aCoord[ii];
+    RtreeCoord *a2 = &p2->aCoord[ii];
+    if( (!isInt && (a2[0].f<a1[0].f || a2[1].f>a1[1].f)) 
+     || ( isInt && (a2[0].i<a1[0].i || a2[1].i>a1[1].i)) 
+    ){
+      return 0;
+    }
+  }
+  return 1;
+}
+
+/*
+** Return the amount cell p would grow by if it were unioned with pCell.
+*/
+static RtreeDValue cellGrowth(Rtree *pRtree, RtreeCell *p, RtreeCell *pCell){
+  RtreeDValue area;
+  RtreeCell cell;
+  memcpy(&cell, p, sizeof(RtreeCell));
+  area = cellArea(pRtree, &cell);
+  cellUnion(pRtree, &cell, pCell);
+  return (cellArea(pRtree, &cell)-area);
+}
+
+static RtreeDValue cellOverlap(
+  Rtree *pRtree, 
+  RtreeCell *p, 
+  RtreeCell *aCell, 
+  int nCell
+){
+  int ii;
+  RtreeDValue overlap = RTREE_ZERO;
+  for(ii=0; ii<nCell; ii++){
+    int jj;
+    RtreeDValue o = (RtreeDValue)1;
+    for(jj=0; jj<(pRtree->nDim*2); jj+=2){
+      RtreeDValue x1, x2;
+      x1 = MAX(DCOORD(p->aCoord[jj]), DCOORD(aCell[ii].aCoord[jj]));
+      x2 = MIN(DCOORD(p->aCoord[jj+1]), DCOORD(aCell[ii].aCoord[jj+1]));
+      if( x2<x1 ){
+        o = (RtreeDValue)0;
+        break;
+      }else{
+        o = o * (x2-x1);
+      }
+    }
+    overlap += o;
+  }
+  return overlap;
+}
+
+
+/*
+** This function implements the ChooseLeaf algorithm from Gutman[84].
+** ChooseSubTree in r*tree terminology.
+*/
+static int ChooseLeaf(
+  Rtree *pRtree,               /* Rtree table */
+  RtreeCell *pCell,            /* Cell to insert into rtree */
+  int iHeight,                 /* Height of sub-tree rooted at pCell */
+  RtreeNode **ppLeaf           /* OUT: Selected leaf page */
+){
+  int rc;
+  int ii;
+  RtreeNode *pNode;
+  rc = nodeAcquire(pRtree, 1, 0, &pNode);
+
+  for(ii=0; rc==SQLITE_OK && ii<(pRtree->iDepth-iHeight); ii++){
+    int iCell;
+    sqlite3_int64 iBest = 0;
+
+    RtreeDValue fMinGrowth = RTREE_ZERO;
+    RtreeDValue fMinArea = RTREE_ZERO;
+
+    int nCell = NCELL(pNode);
+    RtreeCell cell;
+    RtreeNode *pChild;
+
+    RtreeCell *aCell = 0;
+
+    /* Select the child node which will be enlarged the least if pCell
+    ** is inserted into it. Resolve ties by choosing the entry with
+    ** the smallest area.
+    */
+    for(iCell=0; iCell<nCell; iCell++){
+      int bBest = 0;
+      RtreeDValue growth;
+      RtreeDValue area;
+      nodeGetCell(pRtree, pNode, iCell, &cell);
+      growth = cellGrowth(pRtree, &cell, pCell);
+      area = cellArea(pRtree, &cell);
+      if( iCell==0||growth<fMinGrowth||(growth==fMinGrowth && area<fMinArea) ){
+        bBest = 1;
+      }
+      if( bBest ){
+        fMinGrowth = growth;
+        fMinArea = area;
+        iBest = cell.iRowid;
+      }
+    }
+
+    sqlite3_free(aCell);
+    rc = nodeAcquire(pRtree, iBest, pNode, &pChild);
+    nodeRelease(pRtree, pNode);
+    pNode = pChild;
+  }
+
+  *ppLeaf = pNode;
+  return rc;
+}
+
+/*
+** A cell with the same content as pCell has just been inserted into
+** the node pNode. This function updates the bounding box cells in
+** all ancestor elements.
+*/
+static int AdjustTree(
+  Rtree *pRtree,                    /* Rtree table */
+  RtreeNode *pNode,                 /* Adjust ancestry of this node. */
+  RtreeCell *pCell                  /* This cell was just inserted */
+){
+  RtreeNode *p = pNode;
+  while( p->pParent ){
+    RtreeNode *pParent = p->pParent;
+    RtreeCell cell;
+    int iCell;
+
+    if( nodeParentIndex(pRtree, p, &iCell) ){
+      return SQLITE_CORRUPT_VTAB;
+    }
+
+    nodeGetCell(pRtree, pParent, iCell, &cell);
+    if( !cellContains(pRtree, &cell, pCell) ){
+      cellUnion(pRtree, &cell, pCell);
+      nodeOverwriteCell(pRtree, pParent, &cell, iCell);
+    }
+ 
+    p = pParent;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Write mapping (iRowid->iNode) to the <rtree>_rowid table.
+*/
+static int rowidWrite(Rtree *pRtree, sqlite3_int64 iRowid, sqlite3_int64 iNode){
+  sqlite3_bind_int64(pRtree->pWriteRowid, 1, iRowid);
+  sqlite3_bind_int64(pRtree->pWriteRowid, 2, iNode);
+  sqlite3_step(pRtree->pWriteRowid);
+  return sqlite3_reset(pRtree->pWriteRowid);
+}
+
+/*
+** Write mapping (iNode->iPar) to the <rtree>_parent table.
+*/
+static int parentWrite(Rtree *pRtree, sqlite3_int64 iNode, sqlite3_int64 iPar){
+  sqlite3_bind_int64(pRtree->pWriteParent, 1, iNode);
+  sqlite3_bind_int64(pRtree->pWriteParent, 2, iPar);
+  sqlite3_step(pRtree->pWriteParent);
+  return sqlite3_reset(pRtree->pWriteParent);
+}
+
+static int rtreeInsertCell(Rtree *, RtreeNode *, RtreeCell *, int);
+
+
+/*
+** Arguments aIdx, aDistance and aSpare all point to arrays of size
+** nIdx. The aIdx array contains the set of integers from 0 to 
+** (nIdx-1) in no particular order. This function sorts the values
+** in aIdx according to the indexed values in aDistance. For
+** example, assuming the inputs:
+**
+**   aIdx      = { 0,   1,   2,   3 }
+**   aDistance = { 5.0, 2.0, 7.0, 6.0 }
+**
+** this function sets the aIdx array to contain:
+**
+**   aIdx      = { 0,   1,   2,   3 }
+**
+** The aSpare array is used as temporary working space by the
+** sorting algorithm.
+*/
+static void SortByDistance(
+  int *aIdx, 
+  int nIdx, 
+  RtreeDValue *aDistance, 
+  int *aSpare
+){
+  if( nIdx>1 ){
+    int iLeft = 0;
+    int iRight = 0;
+
+    int nLeft = nIdx/2;
+    int nRight = nIdx-nLeft;
+    int *aLeft = aIdx;
+    int *aRight = &aIdx[nLeft];
+
+    SortByDistance(aLeft, nLeft, aDistance, aSpare);
+    SortByDistance(aRight, nRight, aDistance, aSpare);
+
+    memcpy(aSpare, aLeft, sizeof(int)*nLeft);
+    aLeft = aSpare;
+
+    while( iLeft<nLeft || iRight<nRight ){
+      if( iLeft==nLeft ){
+        aIdx[iLeft+iRight] = aRight[iRight];
+        iRight++;
+      }else if( iRight==nRight ){
+        aIdx[iLeft+iRight] = aLeft[iLeft];
+        iLeft++;
+      }else{
+        RtreeDValue fLeft = aDistance[aLeft[iLeft]];
+        RtreeDValue fRight = aDistance[aRight[iRight]];
+        if( fLeft<fRight ){
+          aIdx[iLeft+iRight] = aLeft[iLeft];
+          iLeft++;
+        }else{
+          aIdx[iLeft+iRight] = aRight[iRight];
+          iRight++;
+        }
+      }
+    }
+
+#if 0
+    /* Check that the sort worked */
+    {
+      int jj;
+      for(jj=1; jj<nIdx; jj++){
+        RtreeDValue left = aDistance[aIdx[jj-1]];
+        RtreeDValue right = aDistance[aIdx[jj]];
+        assert( left<=right );
+      }
+    }
+#endif
+  }
+}
+
+/*
+** Arguments aIdx, aCell and aSpare all point to arrays of size
+** nIdx. The aIdx array contains the set of integers from 0 to 
+** (nIdx-1) in no particular order. This function sorts the values
+** in aIdx according to dimension iDim of the cells in aCell. The
+** minimum value of dimension iDim is considered first, the
+** maximum used to break ties.
+**
+** The aSpare array is used as temporary working space by the
+** sorting algorithm.
+*/
+static void SortByDimension(
+  Rtree *pRtree,
+  int *aIdx, 
+  int nIdx, 
+  int iDim, 
+  RtreeCell *aCell, 
+  int *aSpare
+){
+  if( nIdx>1 ){
+
+    int iLeft = 0;
+    int iRight = 0;
+
+    int nLeft = nIdx/2;
+    int nRight = nIdx-nLeft;
+    int *aLeft = aIdx;
+    int *aRight = &aIdx[nLeft];
+
+    SortByDimension(pRtree, aLeft, nLeft, iDim, aCell, aSpare);
+    SortByDimension(pRtree, aRight, nRight, iDim, aCell, aSpare);
+
+    memcpy(aSpare, aLeft, sizeof(int)*nLeft);
+    aLeft = aSpare;
+    while( iLeft<nLeft || iRight<nRight ){
+      RtreeDValue xleft1 = DCOORD(aCell[aLeft[iLeft]].aCoord[iDim*2]);
+      RtreeDValue xleft2 = DCOORD(aCell[aLeft[iLeft]].aCoord[iDim*2+1]);
+      RtreeDValue xright1 = DCOORD(aCell[aRight[iRight]].aCoord[iDim*2]);
+      RtreeDValue xright2 = DCOORD(aCell[aRight[iRight]].aCoord[iDim*2+1]);
+      if( (iLeft!=nLeft) && ((iRight==nRight)
+       || (xleft1<xright1)
+       || (xleft1==xright1 && xleft2<xright2)
+      )){
+        aIdx[iLeft+iRight] = aLeft[iLeft];
+        iLeft++;
+      }else{
+        aIdx[iLeft+iRight] = aRight[iRight];
+        iRight++;
+      }
+    }
+
+#if 0
+    /* Check that the sort worked */
+    {
+      int jj;
+      for(jj=1; jj<nIdx; jj++){
+        RtreeDValue xleft1 = aCell[aIdx[jj-1]].aCoord[iDim*2];
+        RtreeDValue xleft2 = aCell[aIdx[jj-1]].aCoord[iDim*2+1];
+        RtreeDValue xright1 = aCell[aIdx[jj]].aCoord[iDim*2];
+        RtreeDValue xright2 = aCell[aIdx[jj]].aCoord[iDim*2+1];
+        assert( xleft1<=xright1 && (xleft1<xright1 || xleft2<=xright2) );
+      }
+    }
+#endif
+  }
+}
+
+/*
+** Implementation of the R*-tree variant of SplitNode from Beckman[1990].
+*/
+static int splitNodeStartree(
+  Rtree *pRtree,
+  RtreeCell *aCell,
+  int nCell,
+  RtreeNode *pLeft,
+  RtreeNode *pRight,
+  RtreeCell *pBboxLeft,
+  RtreeCell *pBboxRight
+){
+  int **aaSorted;
+  int *aSpare;
+  int ii;
+
+  int iBestDim = 0;
+  int iBestSplit = 0;
+  RtreeDValue fBestMargin = RTREE_ZERO;
+
+  int nByte = (pRtree->nDim+1)*(sizeof(int*)+nCell*sizeof(int));
+
+  aaSorted = (int **)sqlite3_malloc(nByte);
+  if( !aaSorted ){
+    return SQLITE_NOMEM;
+  }
+
+  aSpare = &((int *)&aaSorted[pRtree->nDim])[pRtree->nDim*nCell];
+  memset(aaSorted, 0, nByte);
+  for(ii=0; ii<pRtree->nDim; ii++){
+    int jj;
+    aaSorted[ii] = &((int *)&aaSorted[pRtree->nDim])[ii*nCell];
+    for(jj=0; jj<nCell; jj++){
+      aaSorted[ii][jj] = jj;
+    }
+    SortByDimension(pRtree, aaSorted[ii], nCell, ii, aCell, aSpare);
+  }
+
+  for(ii=0; ii<pRtree->nDim; ii++){
+    RtreeDValue margin = RTREE_ZERO;
+    RtreeDValue fBestOverlap = RTREE_ZERO;
+    RtreeDValue fBestArea = RTREE_ZERO;
+    int iBestLeft = 0;
+    int nLeft;
+
+    for(
+      nLeft=RTREE_MINCELLS(pRtree); 
+      nLeft<=(nCell-RTREE_MINCELLS(pRtree)); 
+      nLeft++
+    ){
+      RtreeCell left;
+      RtreeCell right;
+      int kk;
+      RtreeDValue overlap;
+      RtreeDValue area;
+
+      memcpy(&left, &aCell[aaSorted[ii][0]], sizeof(RtreeCell));
+      memcpy(&right, &aCell[aaSorted[ii][nCell-1]], sizeof(RtreeCell));
+      for(kk=1; kk<(nCell-1); kk++){
+        if( kk<nLeft ){
+          cellUnion(pRtree, &left, &aCell[aaSorted[ii][kk]]);
+        }else{
+          cellUnion(pRtree, &right, &aCell[aaSorted[ii][kk]]);
+        }
+      }
+      margin += cellMargin(pRtree, &left);
+      margin += cellMargin(pRtree, &right);
+      overlap = cellOverlap(pRtree, &left, &right, 1);
+      area = cellArea(pRtree, &left) + cellArea(pRtree, &right);
+      if( (nLeft==RTREE_MINCELLS(pRtree))
+       || (overlap<fBestOverlap)
+       || (overlap==fBestOverlap && area<fBestArea)
+      ){
+        iBestLeft = nLeft;
+        fBestOverlap = overlap;
+        fBestArea = area;
+      }
+    }
+
+    if( ii==0 || margin<fBestMargin ){
+      iBestDim = ii;
+      fBestMargin = margin;
+      iBestSplit = iBestLeft;
+    }
+  }
+
+  memcpy(pBboxLeft, &aCell[aaSorted[iBestDim][0]], sizeof(RtreeCell));
+  memcpy(pBboxRight, &aCell[aaSorted[iBestDim][iBestSplit]], sizeof(RtreeCell));
+  for(ii=0; ii<nCell; ii++){
+    RtreeNode *pTarget = (ii<iBestSplit)?pLeft:pRight;
+    RtreeCell *pBbox = (ii<iBestSplit)?pBboxLeft:pBboxRight;
+    RtreeCell *pCell = &aCell[aaSorted[iBestDim][ii]];
+    nodeInsertCell(pRtree, pTarget, pCell);
+    cellUnion(pRtree, pBbox, pCell);
+  }
+
+  sqlite3_free(aaSorted);
+  return SQLITE_OK;
+}
+
+
+static int updateMapping(
+  Rtree *pRtree, 
+  i64 iRowid, 
+  RtreeNode *pNode, 
+  int iHeight
+){
+  int (*xSetMapping)(Rtree *, sqlite3_int64, sqlite3_int64);
+  xSetMapping = ((iHeight==0)?rowidWrite:parentWrite);
+  if( iHeight>0 ){
+    RtreeNode *pChild = nodeHashLookup(pRtree, iRowid);
+    if( pChild ){
+      nodeRelease(pRtree, pChild->pParent);
+      nodeReference(pNode);
+      pChild->pParent = pNode;
+    }
+  }
+  return xSetMapping(pRtree, iRowid, pNode->iNode);
+}
+
+static int SplitNode(
+  Rtree *pRtree,
+  RtreeNode *pNode,
+  RtreeCell *pCell,
+  int iHeight
+){
+  int i;
+  int newCellIsRight = 0;
+
+  int rc = SQLITE_OK;
+  int nCell = NCELL(pNode);
+  RtreeCell *aCell;
+  int *aiUsed;
+
+  RtreeNode *pLeft = 0;
+  RtreeNode *pRight = 0;
+
+  RtreeCell leftbbox;
+  RtreeCell rightbbox;
+
+  /* Allocate an array and populate it with a copy of pCell and 
+  ** all cells from node pLeft. Then zero the original node.
+  */
+  aCell = sqlite3_malloc((sizeof(RtreeCell)+sizeof(int))*(nCell+1));
+  if( !aCell ){
+    rc = SQLITE_NOMEM;
+    goto splitnode_out;
+  }
+  aiUsed = (int *)&aCell[nCell+1];
+  memset(aiUsed, 0, sizeof(int)*(nCell+1));
+  for(i=0; i<nCell; i++){
+    nodeGetCell(pRtree, pNode, i, &aCell[i]);
+  }
+  nodeZero(pRtree, pNode);
+  memcpy(&aCell[nCell], pCell, sizeof(RtreeCell));
+  nCell++;
+
+  if( pNode->iNode==1 ){
+    pRight = nodeNew(pRtree, pNode);
+    pLeft = nodeNew(pRtree, pNode);
+    pRtree->iDepth++;
+    pNode->isDirty = 1;
+    writeInt16(pNode->zData, pRtree->iDepth);
+  }else{
+    pLeft = pNode;
+    pRight = nodeNew(pRtree, pLeft->pParent);
+    nodeReference(pLeft);
+  }
+
+  if( !pLeft || !pRight ){
+    rc = SQLITE_NOMEM;
+    goto splitnode_out;
+  }
+
+  memset(pLeft->zData, 0, pRtree->iNodeSize);
+  memset(pRight->zData, 0, pRtree->iNodeSize);
+
+  rc = splitNodeStartree(pRtree, aCell, nCell, pLeft, pRight,
+                         &leftbbox, &rightbbox);
+  if( rc!=SQLITE_OK ){
+    goto splitnode_out;
+  }
+
+  /* Ensure both child nodes have node numbers assigned to them by calling
+  ** nodeWrite(). Node pRight always needs a node number, as it was created
+  ** by nodeNew() above. But node pLeft sometimes already has a node number.
+  ** In this case avoid the all to nodeWrite().
+  */
+  if( SQLITE_OK!=(rc = nodeWrite(pRtree, pRight))
+   || (0==pLeft->iNode && SQLITE_OK!=(rc = nodeWrite(pRtree, pLeft)))
+  ){
+    goto splitnode_out;
+  }
+
+  rightbbox.iRowid = pRight->iNode;
+  leftbbox.iRowid = pLeft->iNode;
+
+  if( pNode->iNode==1 ){
+    rc = rtreeInsertCell(pRtree, pLeft->pParent, &leftbbox, iHeight+1);
+    if( rc!=SQLITE_OK ){
+      goto splitnode_out;
+    }
+  }else{
+    RtreeNode *pParent = pLeft->pParent;
+    int iCell;
+    rc = nodeParentIndex(pRtree, pLeft, &iCell);
+    if( rc==SQLITE_OK ){
+      nodeOverwriteCell(pRtree, pParent, &leftbbox, iCell);
+      rc = AdjustTree(pRtree, pParent, &leftbbox);
+    }
+    if( rc!=SQLITE_OK ){
+      goto splitnode_out;
+    }
+  }
+  if( (rc = rtreeInsertCell(pRtree, pRight->pParent, &rightbbox, iHeight+1)) ){
+    goto splitnode_out;
+  }
+
+  for(i=0; i<NCELL(pRight); i++){
+    i64 iRowid = nodeGetRowid(pRtree, pRight, i);
+    rc = updateMapping(pRtree, iRowid, pRight, iHeight);
+    if( iRowid==pCell->iRowid ){
+      newCellIsRight = 1;
+    }
+    if( rc!=SQLITE_OK ){
+      goto splitnode_out;
+    }
+  }
+  if( pNode->iNode==1 ){
+    for(i=0; i<NCELL(pLeft); i++){
+      i64 iRowid = nodeGetRowid(pRtree, pLeft, i);
+      rc = updateMapping(pRtree, iRowid, pLeft, iHeight);
+      if( rc!=SQLITE_OK ){
+        goto splitnode_out;
+      }
+    }
+  }else if( newCellIsRight==0 ){
+    rc = updateMapping(pRtree, pCell->iRowid, pLeft, iHeight);
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = nodeRelease(pRtree, pRight);
+    pRight = 0;
+  }
+  if( rc==SQLITE_OK ){
+    rc = nodeRelease(pRtree, pLeft);
+    pLeft = 0;
+  }
+
+splitnode_out:
+  nodeRelease(pRtree, pRight);
+  nodeRelease(pRtree, pLeft);
+  sqlite3_free(aCell);
+  return rc;
+}
+
+/*
+** If node pLeaf is not the root of the r-tree and its pParent pointer is 
+** still NULL, load all ancestor nodes of pLeaf into memory and populate
+** the pLeaf->pParent chain all the way up to the root node.
+**
+** This operation is required when a row is deleted (or updated - an update
+** is implemented as a delete followed by an insert). SQLite provides the
+** rowid of the row to delete, which can be used to find the leaf on which
+** the entry resides (argument pLeaf). Once the leaf is located, this 
+** function is called to determine its ancestry.
+*/
+static int fixLeafParent(Rtree *pRtree, RtreeNode *pLeaf){
+  int rc = SQLITE_OK;
+  RtreeNode *pChild = pLeaf;
+  while( rc==SQLITE_OK && pChild->iNode!=1 && pChild->pParent==0 ){
+    int rc2 = SQLITE_OK;          /* sqlite3_reset() return code */
+    sqlite3_bind_int64(pRtree->pReadParent, 1, pChild->iNode);
+    rc = sqlite3_step(pRtree->pReadParent);
+    if( rc==SQLITE_ROW ){
+      RtreeNode *pTest;           /* Used to test for reference loops */
+      i64 iNode;                  /* Node number of parent node */
+
+      /* Before setting pChild->pParent, test that we are not creating a
+      ** loop of references (as we would if, say, pChild==pParent). We don't
+      ** want to do this as it leads to a memory leak when trying to delete
+      ** the referenced counted node structures.
+      */
+      iNode = sqlite3_column_int64(pRtree->pReadParent, 0);
+      for(pTest=pLeaf; pTest && pTest->iNode!=iNode; pTest=pTest->pParent);
+      if( !pTest ){
+        rc2 = nodeAcquire(pRtree, iNode, 0, &pChild->pParent);
+      }
+    }
+    rc = sqlite3_reset(pRtree->pReadParent);
+    if( rc==SQLITE_OK ) rc = rc2;
+    if( rc==SQLITE_OK && !pChild->pParent ) rc = SQLITE_CORRUPT_VTAB;
+    pChild = pChild->pParent;
+  }
+  return rc;
+}
+
+static int deleteCell(Rtree *, RtreeNode *, int, int);
+
+static int removeNode(Rtree *pRtree, RtreeNode *pNode, int iHeight){
+  int rc;
+  int rc2;
+  RtreeNode *pParent = 0;
+  int iCell;
+
+  assert( pNode->nRef==1 );
+
+  /* Remove the entry in the parent cell. */
+  rc = nodeParentIndex(pRtree, pNode, &iCell);
+  if( rc==SQLITE_OK ){
+    pParent = pNode->pParent;
+    pNode->pParent = 0;
+    rc = deleteCell(pRtree, pParent, iCell, iHeight+1);
+  }
+  rc2 = nodeRelease(pRtree, pParent);
+  if( rc==SQLITE_OK ){
+    rc = rc2;
+  }
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+
+  /* Remove the xxx_node entry. */
+  sqlite3_bind_int64(pRtree->pDeleteNode, 1, pNode->iNode);
+  sqlite3_step(pRtree->pDeleteNode);
+  if( SQLITE_OK!=(rc = sqlite3_reset(pRtree->pDeleteNode)) ){
+    return rc;
+  }
+
+  /* Remove the xxx_parent entry. */
+  sqlite3_bind_int64(pRtree->pDeleteParent, 1, pNode->iNode);
+  sqlite3_step(pRtree->pDeleteParent);
+  if( SQLITE_OK!=(rc = sqlite3_reset(pRtree->pDeleteParent)) ){
+    return rc;
+  }
+  
+  /* Remove the node from the in-memory hash table and link it into
+  ** the Rtree.pDeleted list. Its contents will be re-inserted later on.
+  */
+  nodeHashDelete(pRtree, pNode);
+  pNode->iNode = iHeight;
+  pNode->pNext = pRtree->pDeleted;
+  pNode->nRef++;
+  pRtree->pDeleted = pNode;
+
+  return SQLITE_OK;
+}
+
+static int fixBoundingBox(Rtree *pRtree, RtreeNode *pNode){
+  RtreeNode *pParent = pNode->pParent;
+  int rc = SQLITE_OK; 
+  if( pParent ){
+    int ii; 
+    int nCell = NCELL(pNode);
+    RtreeCell box;                            /* Bounding box for pNode */
+    nodeGetCell(pRtree, pNode, 0, &box);
+    for(ii=1; ii<nCell; ii++){
+      RtreeCell cell;
+      nodeGetCell(pRtree, pNode, ii, &cell);
+      cellUnion(pRtree, &box, &cell);
+    }
+    box.iRowid = pNode->iNode;
+    rc = nodeParentIndex(pRtree, pNode, &ii);
+    if( rc==SQLITE_OK ){
+      nodeOverwriteCell(pRtree, pParent, &box, ii);
+      rc = fixBoundingBox(pRtree, pParent);
+    }
+  }
+  return rc;
+}
+
+/*
+** Delete the cell at index iCell of node pNode. After removing the
+** cell, adjust the r-tree data structure if required.
+*/
+static int deleteCell(Rtree *pRtree, RtreeNode *pNode, int iCell, int iHeight){
+  RtreeNode *pParent;
+  int rc;
+
+  if( SQLITE_OK!=(rc = fixLeafParent(pRtree, pNode)) ){
+    return rc;
+  }
+
+  /* Remove the cell from the node. This call just moves bytes around
+  ** the in-memory node image, so it cannot fail.
+  */
+  nodeDeleteCell(pRtree, pNode, iCell);
+
+  /* If the node is not the tree root and now has less than the minimum
+  ** number of cells, remove it from the tree. Otherwise, update the
+  ** cell in the parent node so that it tightly contains the updated
+  ** node.
+  */
+  pParent = pNode->pParent;
+  assert( pParent || pNode->iNode==1 );
+  if( pParent ){
+    if( NCELL(pNode)<RTREE_MINCELLS(pRtree) ){
+      rc = removeNode(pRtree, pNode, iHeight);
+    }else{
+      rc = fixBoundingBox(pRtree, pNode);
+    }
+  }
+
+  return rc;
+}
+
+static int Reinsert(
+  Rtree *pRtree, 
+  RtreeNode *pNode, 
+  RtreeCell *pCell, 
+  int iHeight
+){
+  int *aOrder;
+  int *aSpare;
+  RtreeCell *aCell;
+  RtreeDValue *aDistance;
+  int nCell;
+  RtreeDValue aCenterCoord[RTREE_MAX_DIMENSIONS];
+  int iDim;
+  int ii;
+  int rc = SQLITE_OK;
+  int n;
+
+  memset(aCenterCoord, 0, sizeof(RtreeDValue)*RTREE_MAX_DIMENSIONS);
+
+  nCell = NCELL(pNode)+1;
+  n = (nCell+1)&(~1);
+
+  /* Allocate the buffers used by this operation. The allocation is
+  ** relinquished before this function returns.
+  */
+  aCell = (RtreeCell *)sqlite3_malloc(n * (
+    sizeof(RtreeCell)     +         /* aCell array */
+    sizeof(int)           +         /* aOrder array */
+    sizeof(int)           +         /* aSpare array */
+    sizeof(RtreeDValue)             /* aDistance array */
+  ));
+  if( !aCell ){
+    return SQLITE_NOMEM;
+  }
+  aOrder    = (int *)&aCell[n];
+  aSpare    = (int *)&aOrder[n];
+  aDistance = (RtreeDValue *)&aSpare[n];
+
+  for(ii=0; ii<nCell; ii++){
+    if( ii==(nCell-1) ){
+      memcpy(&aCell[ii], pCell, sizeof(RtreeCell));
+    }else{
+      nodeGetCell(pRtree, pNode, ii, &aCell[ii]);
+    }
+    aOrder[ii] = ii;
+    for(iDim=0; iDim<pRtree->nDim; iDim++){
+      aCenterCoord[iDim] += DCOORD(aCell[ii].aCoord[iDim*2]);
+      aCenterCoord[iDim] += DCOORD(aCell[ii].aCoord[iDim*2+1]);
+    }
+  }
+  for(iDim=0; iDim<pRtree->nDim; iDim++){
+    aCenterCoord[iDim] = (aCenterCoord[iDim]/(nCell*(RtreeDValue)2));
+  }
+
+  for(ii=0; ii<nCell; ii++){
+    aDistance[ii] = RTREE_ZERO;
+    for(iDim=0; iDim<pRtree->nDim; iDim++){
+      RtreeDValue coord = (DCOORD(aCell[ii].aCoord[iDim*2+1]) - 
+                               DCOORD(aCell[ii].aCoord[iDim*2]));
+      aDistance[ii] += (coord-aCenterCoord[iDim])*(coord-aCenterCoord[iDim]);
+    }
+  }
+
+  SortByDistance(aOrder, nCell, aDistance, aSpare);
+  nodeZero(pRtree, pNode);
+
+  for(ii=0; rc==SQLITE_OK && ii<(nCell-(RTREE_MINCELLS(pRtree)+1)); ii++){
+    RtreeCell *p = &aCell[aOrder[ii]];
+    nodeInsertCell(pRtree, pNode, p);
+    if( p->iRowid==pCell->iRowid ){
+      if( iHeight==0 ){
+        rc = rowidWrite(pRtree, p->iRowid, pNode->iNode);
+      }else{
+        rc = parentWrite(pRtree, p->iRowid, pNode->iNode);
+      }
+    }
+  }
+  if( rc==SQLITE_OK ){
+    rc = fixBoundingBox(pRtree, pNode);
+  }
+  for(; rc==SQLITE_OK && ii<nCell; ii++){
+    /* Find a node to store this cell in. pNode->iNode currently contains
+    ** the height of the sub-tree headed by the cell.
+    */
+    RtreeNode *pInsert;
+    RtreeCell *p = &aCell[aOrder[ii]];
+    rc = ChooseLeaf(pRtree, p, iHeight, &pInsert);
+    if( rc==SQLITE_OK ){
+      int rc2;
+      rc = rtreeInsertCell(pRtree, pInsert, p, iHeight);
+      rc2 = nodeRelease(pRtree, pInsert);
+      if( rc==SQLITE_OK ){
+        rc = rc2;
+      }
+    }
+  }
+
+  sqlite3_free(aCell);
+  return rc;
+}
+
+/*
+** Insert cell pCell into node pNode. Node pNode is the head of a 
+** subtree iHeight high (leaf nodes have iHeight==0).
+*/
+static int rtreeInsertCell(
+  Rtree *pRtree,
+  RtreeNode *pNode,
+  RtreeCell *pCell,
+  int iHeight
+){
+  int rc = SQLITE_OK;
+  if( iHeight>0 ){
+    RtreeNode *pChild = nodeHashLookup(pRtree, pCell->iRowid);
+    if( pChild ){
+      nodeRelease(pRtree, pChild->pParent);
+      nodeReference(pNode);
+      pChild->pParent = pNode;
+    }
+  }
+  if( nodeInsertCell(pRtree, pNode, pCell) ){
+    if( iHeight<=pRtree->iReinsertHeight || pNode->iNode==1){
+      rc = SplitNode(pRtree, pNode, pCell, iHeight);
+    }else{
+      pRtree->iReinsertHeight = iHeight;
+      rc = Reinsert(pRtree, pNode, pCell, iHeight);
+    }
+  }else{
+    rc = AdjustTree(pRtree, pNode, pCell);
+    if( rc==SQLITE_OK ){
+      if( iHeight==0 ){
+        rc = rowidWrite(pRtree, pCell->iRowid, pNode->iNode);
+      }else{
+        rc = parentWrite(pRtree, pCell->iRowid, pNode->iNode);
+      }
+    }
+  }
+  return rc;
+}
+
+static int reinsertNodeContent(Rtree *pRtree, RtreeNode *pNode){
+  int ii;
+  int rc = SQLITE_OK;
+  int nCell = NCELL(pNode);
+
+  for(ii=0; rc==SQLITE_OK && ii<nCell; ii++){
+    RtreeNode *pInsert;
+    RtreeCell cell;
+    nodeGetCell(pRtree, pNode, ii, &cell);
+
+    /* Find a node to store this cell in. pNode->iNode currently contains
+    ** the height of the sub-tree headed by the cell.
+    */
+    rc = ChooseLeaf(pRtree, &cell, (int)pNode->iNode, &pInsert);
+    if( rc==SQLITE_OK ){
+      int rc2;
+      rc = rtreeInsertCell(pRtree, pInsert, &cell, (int)pNode->iNode);
+      rc2 = nodeRelease(pRtree, pInsert);
+      if( rc==SQLITE_OK ){
+        rc = rc2;
+      }
+    }
+  }
+  return rc;
+}
+
+/*
+** Select a currently unused rowid for a new r-tree record.
+*/
+static int newRowid(Rtree *pRtree, i64 *piRowid){
+  int rc;
+  sqlite3_bind_null(pRtree->pWriteRowid, 1);
+  sqlite3_bind_null(pRtree->pWriteRowid, 2);
+  sqlite3_step(pRtree->pWriteRowid);
+  rc = sqlite3_reset(pRtree->pWriteRowid);
+  *piRowid = sqlite3_last_insert_rowid(pRtree->db);
+  return rc;
+}
+
+/*
+** Remove the entry with rowid=iDelete from the r-tree structure.
+*/
+static int rtreeDeleteRowid(Rtree *pRtree, sqlite3_int64 iDelete){
+  int rc;                         /* Return code */
+  RtreeNode *pLeaf = 0;           /* Leaf node containing record iDelete */
+  int iCell;                      /* Index of iDelete cell in pLeaf */
+  RtreeNode *pRoot;               /* Root node of rtree structure */
+
+
+  /* Obtain a reference to the root node to initialize Rtree.iDepth */
+  rc = nodeAcquire(pRtree, 1, 0, &pRoot);
+
+  /* Obtain a reference to the leaf node that contains the entry 
+  ** about to be deleted. 
+  */
+  if( rc==SQLITE_OK ){
+    rc = findLeafNode(pRtree, iDelete, &pLeaf, 0);
+  }
+
+  /* Delete the cell in question from the leaf node. */
+  if( rc==SQLITE_OK ){
+    int rc2;
+    rc = nodeRowidIndex(pRtree, pLeaf, iDelete, &iCell);
+    if( rc==SQLITE_OK ){
+      rc = deleteCell(pRtree, pLeaf, iCell, 0);
+    }
+    rc2 = nodeRelease(pRtree, pLeaf);
+    if( rc==SQLITE_OK ){
+      rc = rc2;
+    }
+  }
+
+  /* Delete the corresponding entry in the <rtree>_rowid table. */
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int64(pRtree->pDeleteRowid, 1, iDelete);
+    sqlite3_step(pRtree->pDeleteRowid);
+    rc = sqlite3_reset(pRtree->pDeleteRowid);
+  }
+
+  /* Check if the root node now has exactly one child. If so, remove
+  ** it, schedule the contents of the child for reinsertion and 
+  ** reduce the tree height by one.
+  **
+  ** This is equivalent to copying the contents of the child into
+  ** the root node (the operation that Gutman's paper says to perform 
+  ** in this scenario).
+  */
+  if( rc==SQLITE_OK && pRtree->iDepth>0 && NCELL(pRoot)==1 ){
+    int rc2;
+    RtreeNode *pChild;
+    i64 iChild = nodeGetRowid(pRtree, pRoot, 0);
+    rc = nodeAcquire(pRtree, iChild, pRoot, &pChild);
+    if( rc==SQLITE_OK ){
+      rc = removeNode(pRtree, pChild, pRtree->iDepth-1);
+    }
+    rc2 = nodeRelease(pRtree, pChild);
+    if( rc==SQLITE_OK ) rc = rc2;
+    if( rc==SQLITE_OK ){
+      pRtree->iDepth--;
+      writeInt16(pRoot->zData, pRtree->iDepth);
+      pRoot->isDirty = 1;
+    }
+  }
+
+  /* Re-insert the contents of any underfull nodes removed from the tree. */
+  for(pLeaf=pRtree->pDeleted; pLeaf; pLeaf=pRtree->pDeleted){
+    if( rc==SQLITE_OK ){
+      rc = reinsertNodeContent(pRtree, pLeaf);
+    }
+    pRtree->pDeleted = pLeaf->pNext;
+    sqlite3_free(pLeaf);
+  }
+
+  /* Release the reference to the root node. */
+  if( rc==SQLITE_OK ){
+    rc = nodeRelease(pRtree, pRoot);
+  }else{
+    nodeRelease(pRtree, pRoot);
+  }
+
+  return rc;
+}
+
+/*
+** Rounding constants for float->double conversion.
+*/
+#define RNDTOWARDS  (1.0 - 1.0/8388608.0)  /* Round towards zero */
+#define RNDAWAY     (1.0 + 1.0/8388608.0)  /* Round away from zero */
+
+#if !defined(SQLITE_RTREE_INT_ONLY)
+/*
+** Convert an sqlite3_value into an RtreeValue (presumably a float)
+** while taking care to round toward negative or positive, respectively.
+*/
+static RtreeValue rtreeValueDown(sqlite3_value *v){
+  double d = sqlite3_value_double(v);
+  float f = (float)d;
+  if( f>d ){
+    f = (float)(d*(d<0 ? RNDAWAY : RNDTOWARDS));
+  }
+  return f;
+}
+static RtreeValue rtreeValueUp(sqlite3_value *v){
+  double d = sqlite3_value_double(v);
+  float f = (float)d;
+  if( f<d ){
+    f = (float)(d*(d<0 ? RNDTOWARDS : RNDAWAY));
+  }
+  return f;
+}
+#endif /* !defined(SQLITE_RTREE_INT_ONLY) */
+
+/*
+** A constraint has failed while inserting a row into an rtree table. 
+** Assuming no OOM error occurs, this function sets the error message 
+** (at pRtree->base.zErrMsg) to an appropriate value and returns
+** SQLITE_CONSTRAINT.
+**
+** Parameter iCol is the index of the leftmost column involved in the
+** constraint failure. If it is 0, then the constraint that failed is
+** the unique constraint on the id column. Otherwise, it is the rtree
+** (c1<=c2) constraint on columns iCol and iCol+1 that has failed.
+**
+** If an OOM occurs, SQLITE_NOMEM is returned instead of SQLITE_CONSTRAINT.
+*/
+static int rtreeConstraintError(Rtree *pRtree, int iCol){
+  sqlite3_stmt *pStmt = 0;
+  char *zSql; 
+  int rc;
+
+  assert( iCol==0 || iCol%2 );
+  zSql = sqlite3_mprintf("SELECT * FROM %Q.%Q", pRtree->zDb, pRtree->zName);
+  if( zSql ){
+    rc = sqlite3_prepare_v2(pRtree->db, zSql, -1, &pStmt, 0);
+  }else{
+    rc = SQLITE_NOMEM;
+  }
+  sqlite3_free(zSql);
+
+  if( rc==SQLITE_OK ){
+    if( iCol==0 ){
+      const char *zCol = sqlite3_column_name(pStmt, 0);
+      pRtree->base.zErrMsg = sqlite3_mprintf(
+          "UNIQUE constraint failed: %s.%s", pRtree->zName, zCol
+      );
+    }else{
+      const char *zCol1 = sqlite3_column_name(pStmt, iCol);
+      const char *zCol2 = sqlite3_column_name(pStmt, iCol+1);
+      pRtree->base.zErrMsg = sqlite3_mprintf(
+          "rtree constraint failed: %s.(%s<=%s)", pRtree->zName, zCol1, zCol2
+      );
+    }
+  }
+
+  sqlite3_finalize(pStmt);
+  return (rc==SQLITE_OK ? SQLITE_CONSTRAINT : rc);
+}
+
+
+
+/*
+** The xUpdate method for rtree module virtual tables.
+*/
+static int rtreeUpdate(
+  sqlite3_vtab *pVtab, 
+  int nData, 
+  sqlite3_value **azData, 
+  sqlite_int64 *pRowid
+){
+  Rtree *pRtree = (Rtree *)pVtab;
+  int rc = SQLITE_OK;
+  RtreeCell cell;                 /* New cell to insert if nData>1 */
+  int bHaveRowid = 0;             /* Set to 1 after new rowid is determined */
+
+  rtreeReference(pRtree);
+  assert(nData>=1);
+
+  cell.iRowid = 0;  /* Used only to suppress a compiler warning */
+
+  /* Constraint handling. A write operation on an r-tree table may return
+  ** SQLITE_CONSTRAINT for two reasons:
+  **
+  **   1. A duplicate rowid value, or
+  **   2. The supplied data violates the "x2>=x1" constraint.
+  **
+  ** In the first case, if the conflict-handling mode is REPLACE, then
+  ** the conflicting row can be removed before proceeding. In the second
+  ** case, SQLITE_CONSTRAINT must be returned regardless of the
+  ** conflict-handling mode specified by the user.
+  */
+  if( nData>1 ){
+    int ii;
+
+    /* Populate the cell.aCoord[] array. The first coordinate is azData[3].
+    **
+    ** NB: nData can only be less than nDim*2+3 if the rtree is mis-declared
+    ** with "column" that are interpreted as table constraints.
+    ** Example:  CREATE VIRTUAL TABLE bad USING rtree(x,y,CHECK(y>5));
+    ** This problem was discovered after years of use, so we silently ignore
+    ** these kinds of misdeclared tables to avoid breaking any legacy.
+    */
+    assert( nData<=(pRtree->nDim*2 + 3) );
+
+#ifndef SQLITE_RTREE_INT_ONLY
+    if( pRtree->eCoordType==RTREE_COORD_REAL32 ){
+      for(ii=0; ii<nData-4; ii+=2){
+        cell.aCoord[ii].f = rtreeValueDown(azData[ii+3]);
+        cell.aCoord[ii+1].f = rtreeValueUp(azData[ii+4]);
+        if( cell.aCoord[ii].f>cell.aCoord[ii+1].f ){
+          rc = rtreeConstraintError(pRtree, ii+1);
+          goto constraint;
+        }
+      }
+    }else
+#endif
+    {
+      for(ii=0; ii<nData-4; ii+=2){
+        cell.aCoord[ii].i = sqlite3_value_int(azData[ii+3]);
+        cell.aCoord[ii+1].i = sqlite3_value_int(azData[ii+4]);
+        if( cell.aCoord[ii].i>cell.aCoord[ii+1].i ){
+          rc = rtreeConstraintError(pRtree, ii+1);
+          goto constraint;
+        }
+      }
+    }
+
+    /* If a rowid value was supplied, check if it is already present in 
+    ** the table. If so, the constraint has failed. */
+    if( sqlite3_value_type(azData[2])!=SQLITE_NULL ){
+      cell.iRowid = sqlite3_value_int64(azData[2]);
+      if( sqlite3_value_type(azData[0])==SQLITE_NULL
+       || sqlite3_value_int64(azData[0])!=cell.iRowid
+      ){
+        int steprc;
+        sqlite3_bind_int64(pRtree->pReadRowid, 1, cell.iRowid);
+        steprc = sqlite3_step(pRtree->pReadRowid);
+        rc = sqlite3_reset(pRtree->pReadRowid);
+        if( SQLITE_ROW==steprc ){
+          if( sqlite3_vtab_on_conflict(pRtree->db)==SQLITE_REPLACE ){
+            rc = rtreeDeleteRowid(pRtree, cell.iRowid);
+          }else{
+            rc = rtreeConstraintError(pRtree, 0);
+            goto constraint;
+          }
+        }
+      }
+      bHaveRowid = 1;
+    }
+  }
+
+  /* If azData[0] is not an SQL NULL value, it is the rowid of a
+  ** record to delete from the r-tree table. The following block does
+  ** just that.
+  */
+  if( sqlite3_value_type(azData[0])!=SQLITE_NULL ){
+    rc = rtreeDeleteRowid(pRtree, sqlite3_value_int64(azData[0]));
+  }
+
+  /* If the azData[] array contains more than one element, elements
+  ** (azData[2]..azData[argc-1]) contain a new record to insert into
+  ** the r-tree structure.
+  */
+  if( rc==SQLITE_OK && nData>1 ){
+    /* Insert the new record into the r-tree */
+    RtreeNode *pLeaf = 0;
+
+    /* Figure out the rowid of the new row. */
+    if( bHaveRowid==0 ){
+      rc = newRowid(pRtree, &cell.iRowid);
+    }
+    *pRowid = cell.iRowid;
+
+    if( rc==SQLITE_OK ){
+      rc = ChooseLeaf(pRtree, &cell, 0, &pLeaf);
+    }
+    if( rc==SQLITE_OK ){
+      int rc2;
+      pRtree->iReinsertHeight = -1;
+      rc = rtreeInsertCell(pRtree, pLeaf, &cell, 0);
+      rc2 = nodeRelease(pRtree, pLeaf);
+      if( rc==SQLITE_OK ){
+        rc = rc2;
+      }
+    }
+  }
+
+constraint:
+  rtreeRelease(pRtree);
+  return rc;
+}
+
+/*
+** The xRename method for rtree module virtual tables.
+*/
+static int rtreeRename(sqlite3_vtab *pVtab, const char *zNewName){
+  Rtree *pRtree = (Rtree *)pVtab;
+  int rc = SQLITE_NOMEM;
+  char *zSql = sqlite3_mprintf(
+    "ALTER TABLE %Q.'%q_node'   RENAME TO \"%w_node\";"
+    "ALTER TABLE %Q.'%q_parent' RENAME TO \"%w_parent\";"
+    "ALTER TABLE %Q.'%q_rowid'  RENAME TO \"%w_rowid\";"
+    , pRtree->zDb, pRtree->zName, zNewName 
+    , pRtree->zDb, pRtree->zName, zNewName 
+    , pRtree->zDb, pRtree->zName, zNewName
+  );
+  if( zSql ){
+    rc = sqlite3_exec(pRtree->db, zSql, 0, 0, 0);
+    sqlite3_free(zSql);
+  }
+  return rc;
+}
+
+/*
+** This function populates the pRtree->nRowEst variable with an estimate
+** of the number of rows in the virtual table. If possible, this is based
+** on sqlite_stat1 data. Otherwise, use RTREE_DEFAULT_ROWEST.
+*/
+static int rtreeQueryStat1(sqlite3 *db, Rtree *pRtree){
+  const char *zFmt = "SELECT stat FROM %Q.sqlite_stat1 WHERE tbl = '%q_rowid'";
+  char *zSql;
+  sqlite3_stmt *p;
+  int rc;
+  i64 nRow = 0;
+
+  rc = sqlite3_table_column_metadata(
+      db, pRtree->zDb, "sqlite_stat1",0,0,0,0,0,0
+  );
+  if( rc!=SQLITE_OK ){
+    pRtree->nRowEst = RTREE_DEFAULT_ROWEST;
+    return rc==SQLITE_ERROR ? SQLITE_OK : rc;
+  }
+  zSql = sqlite3_mprintf(zFmt, pRtree->zDb, pRtree->zName);
+  if( zSql==0 ){
+    rc = SQLITE_NOMEM;
+  }else{
+    rc = sqlite3_prepare_v2(db, zSql, -1, &p, 0);
+    if( rc==SQLITE_OK ){
+      if( sqlite3_step(p)==SQLITE_ROW ) nRow = sqlite3_column_int64(p, 0);
+      rc = sqlite3_finalize(p);
+    }else if( rc!=SQLITE_NOMEM ){
+      rc = SQLITE_OK;
+    }
+
+    if( rc==SQLITE_OK ){
+      if( nRow==0 ){
+        pRtree->nRowEst = RTREE_DEFAULT_ROWEST;
+      }else{
+        pRtree->nRowEst = MAX(nRow, RTREE_MIN_ROWEST);
+      }
+    }
+    sqlite3_free(zSql);
+  }
+
+  return rc;
+}
+
+static sqlite3_module rtreeModule = {
+  0,                          /* iVersion */
+  rtreeCreate,                /* xCreate - create a table */
+  rtreeConnect,               /* xConnect - connect to an existing table */
+  rtreeBestIndex,             /* xBestIndex - Determine search strategy */
+  rtreeDisconnect,            /* xDisconnect - Disconnect from a table */
+  rtreeDestroy,               /* xDestroy - Drop a table */
+  rtreeOpen,                  /* xOpen - open a cursor */
+  rtreeClose,                 /* xClose - close a cursor */
+  rtreeFilter,                /* xFilter - configure scan constraints */
+  rtreeNext,                  /* xNext - advance a cursor */
+  rtreeEof,                   /* xEof */
+  rtreeColumn,                /* xColumn - read data */
+  rtreeRowid,                 /* xRowid - read data */
+  rtreeUpdate,                /* xUpdate - write data */
+  0,                          /* xBegin - begin transaction */
+  0,                          /* xSync - sync transaction */
+  0,                          /* xCommit - commit transaction */
+  0,                          /* xRollback - rollback transaction */
+  0,                          /* xFindFunction - function overloading */
+  rtreeRename,                /* xRename - rename the table */
+  0,                          /* xSavepoint */
+  0,                          /* xRelease */
+  0                           /* xRollbackTo */
+};
+
+static int rtreeSqlInit(
+  Rtree *pRtree, 
+  sqlite3 *db, 
+  const char *zDb, 
+  const char *zPrefix, 
+  int isCreate
+){
+  int rc = SQLITE_OK;
+
+  #define N_STATEMENT 9
+  static const char *azSql[N_STATEMENT] = {
+    /* Read and write the xxx_node table */
+    "SELECT data FROM '%q'.'%q_node' WHERE nodeno = :1",
+    "INSERT OR REPLACE INTO '%q'.'%q_node' VALUES(:1, :2)",
+    "DELETE FROM '%q'.'%q_node' WHERE nodeno = :1",
+
+    /* Read and write the xxx_rowid table */
+    "SELECT nodeno FROM '%q'.'%q_rowid' WHERE rowid = :1",
+    "INSERT OR REPLACE INTO '%q'.'%q_rowid' VALUES(:1, :2)",
+    "DELETE FROM '%q'.'%q_rowid' WHERE rowid = :1",
+
+    /* Read and write the xxx_parent table */
+    "SELECT parentnode FROM '%q'.'%q_parent' WHERE nodeno = :1",
+    "INSERT OR REPLACE INTO '%q'.'%q_parent' VALUES(:1, :2)",
+    "DELETE FROM '%q'.'%q_parent' WHERE nodeno = :1"
+  };
+  sqlite3_stmt **appStmt[N_STATEMENT];
+  int i;
+
+  pRtree->db = db;
+
+  if( isCreate ){
+    char *zCreate = sqlite3_mprintf(
+"CREATE TABLE \"%w\".\"%w_node\"(nodeno INTEGER PRIMARY KEY, data BLOB);"
+"CREATE TABLE \"%w\".\"%w_rowid\"(rowid INTEGER PRIMARY KEY, nodeno INTEGER);"
+"CREATE TABLE \"%w\".\"%w_parent\"(nodeno INTEGER PRIMARY KEY,"
+                                  " parentnode INTEGER);"
+"INSERT INTO '%q'.'%q_node' VALUES(1, zeroblob(%d))",
+      zDb, zPrefix, zDb, zPrefix, zDb, zPrefix, zDb, zPrefix, pRtree->iNodeSize
+    );
+    if( !zCreate ){
+      return SQLITE_NOMEM;
+    }
+    rc = sqlite3_exec(db, zCreate, 0, 0, 0);
+    sqlite3_free(zCreate);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+  }
+
+  appStmt[0] = &pRtree->pReadNode;
+  appStmt[1] = &pRtree->pWriteNode;
+  appStmt[2] = &pRtree->pDeleteNode;
+  appStmt[3] = &pRtree->pReadRowid;
+  appStmt[4] = &pRtree->pWriteRowid;
+  appStmt[5] = &pRtree->pDeleteRowid;
+  appStmt[6] = &pRtree->pReadParent;
+  appStmt[7] = &pRtree->pWriteParent;
+  appStmt[8] = &pRtree->pDeleteParent;
+
+  rc = rtreeQueryStat1(db, pRtree);
+  for(i=0; i<N_STATEMENT && rc==SQLITE_OK; i++){
+    char *zSql = sqlite3_mprintf(azSql[i], zDb, zPrefix);
+    if( zSql ){
+      rc = sqlite3_prepare_v2(db, zSql, -1, appStmt[i], 0); 
+    }else{
+      rc = SQLITE_NOMEM;
+    }
+    sqlite3_free(zSql);
+  }
+
+  return rc;
+}
+
+/*
+** The second argument to this function contains the text of an SQL statement
+** that returns a single integer value. The statement is compiled and executed
+** using database connection db. If successful, the integer value returned
+** is written to *piVal and SQLITE_OK returned. Otherwise, an SQLite error
+** code is returned and the value of *piVal after returning is not defined.
+*/
+static int getIntFromStmt(sqlite3 *db, const char *zSql, int *piVal){
+  int rc = SQLITE_NOMEM;
+  if( zSql ){
+    sqlite3_stmt *pStmt = 0;
+    rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
+    if( rc==SQLITE_OK ){
+      if( SQLITE_ROW==sqlite3_step(pStmt) ){
+        *piVal = sqlite3_column_int(pStmt, 0);
+      }
+      rc = sqlite3_finalize(pStmt);
+    }
+  }
+  return rc;
+}
+
+/*
+** This function is called from within the xConnect() or xCreate() method to
+** determine the node-size used by the rtree table being created or connected
+** to. If successful, pRtree->iNodeSize is populated and SQLITE_OK returned.
+** Otherwise, an SQLite error code is returned.
+**
+** If this function is being called as part of an xConnect(), then the rtree
+** table already exists. In this case the node-size is determined by inspecting
+** the root node of the tree.
+**
+** Otherwise, for an xCreate(), use 64 bytes less than the database page-size. 
+** This ensures that each node is stored on a single database page. If the 
+** database page-size is so large that more than RTREE_MAXCELLS entries 
+** would fit in a single node, use a smaller node-size.
+*/
+static int getNodeSize(
+  sqlite3 *db,                    /* Database handle */
+  Rtree *pRtree,                  /* Rtree handle */
+  int isCreate,                   /* True for xCreate, false for xConnect */
+  char **pzErr                    /* OUT: Error message, if any */
+){
+  int rc;
+  char *zSql;
+  if( isCreate ){
+    int iPageSize = 0;
+    zSql = sqlite3_mprintf("PRAGMA %Q.page_size", pRtree->zDb);
+    rc = getIntFromStmt(db, zSql, &iPageSize);
+    if( rc==SQLITE_OK ){
+      pRtree->iNodeSize = iPageSize-64;
+      if( (4+pRtree->nBytesPerCell*RTREE_MAXCELLS)<pRtree->iNodeSize ){
+        pRtree->iNodeSize = 4+pRtree->nBytesPerCell*RTREE_MAXCELLS;
+      }
+    }else{
+      *pzErr = sqlite3_mprintf("%s", sqlite3_errmsg(db));
+    }
+  }else{
+    zSql = sqlite3_mprintf(
+        "SELECT length(data) FROM '%q'.'%q_node' WHERE nodeno = 1",
+        pRtree->zDb, pRtree->zName
+    );
+    rc = getIntFromStmt(db, zSql, &pRtree->iNodeSize);
+    if( rc!=SQLITE_OK ){
+      *pzErr = sqlite3_mprintf("%s", sqlite3_errmsg(db));
+    }
+  }
+
+  sqlite3_free(zSql);
+  return rc;
+}
+
+/* 
+** This function is the implementation of both the xConnect and xCreate
+** methods of the r-tree virtual table.
+**
+**   argv[0]   -> module name
+**   argv[1]   -> database name
+**   argv[2]   -> table name
+**   argv[...] -> column names...
+*/
+static int rtreeInit(
+  sqlite3 *db,                        /* Database connection */
+  void *pAux,                         /* One of the RTREE_COORD_* constants */
+  int argc, const char *const*argv,   /* Parameters to CREATE TABLE statement */
+  sqlite3_vtab **ppVtab,              /* OUT: New virtual table */
+  char **pzErr,                       /* OUT: Error message, if any */
+  int isCreate                        /* True for xCreate, false for xConnect */
+){
+  int rc = SQLITE_OK;
+  Rtree *pRtree;
+  int nDb;              /* Length of string argv[1] */
+  int nName;            /* Length of string argv[2] */
+  int eCoordType = (pAux ? RTREE_COORD_INT32 : RTREE_COORD_REAL32);
+
+  const char *aErrMsg[] = {
+    0,                                                    /* 0 */
+    "Wrong number of columns for an rtree table",         /* 1 */
+    "Too few columns for an rtree table",                 /* 2 */
+    "Too many columns for an rtree table"                 /* 3 */
+  };
+
+  int iErr = (argc<6) ? 2 : argc>(RTREE_MAX_DIMENSIONS*2+4) ? 3 : argc%2;
+  if( aErrMsg[iErr] ){
+    *pzErr = sqlite3_mprintf("%s", aErrMsg[iErr]);
+    return SQLITE_ERROR;
+  }
+
+  sqlite3_vtab_config(db, SQLITE_VTAB_CONSTRAINT_SUPPORT, 1);
+
+  /* Allocate the sqlite3_vtab structure */
+  nDb = (int)strlen(argv[1]);
+  nName = (int)strlen(argv[2]);
+  pRtree = (Rtree *)sqlite3_malloc(sizeof(Rtree)+nDb+nName+2);
+  if( !pRtree ){
+    return SQLITE_NOMEM;
+  }
+  memset(pRtree, 0, sizeof(Rtree)+nDb+nName+2);
+  pRtree->nBusy = 1;
+  pRtree->base.pModule = &rtreeModule;
+  pRtree->zDb = (char *)&pRtree[1];
+  pRtree->zName = &pRtree->zDb[nDb+1];
+  pRtree->nDim = (argc-4)/2;
+  pRtree->nBytesPerCell = 8 + pRtree->nDim*4*2;
+  pRtree->eCoordType = eCoordType;
+  memcpy(pRtree->zDb, argv[1], nDb);
+  memcpy(pRtree->zName, argv[2], nName);
+
+  /* Figure out the node size to use. */
+  rc = getNodeSize(db, pRtree, isCreate, pzErr);
+
+  /* Create/Connect to the underlying relational database schema. If
+  ** that is successful, call sqlite3_declare_vtab() to configure
+  ** the r-tree table schema.
+  */
+  if( rc==SQLITE_OK ){
+    if( (rc = rtreeSqlInit(pRtree, db, argv[1], argv[2], isCreate)) ){
+      *pzErr = sqlite3_mprintf("%s", sqlite3_errmsg(db));
+    }else{
+      char *zSql = sqlite3_mprintf("CREATE TABLE x(%s", argv[3]);
+      char *zTmp;
+      int ii;
+      for(ii=4; zSql && ii<argc; ii++){
+        zTmp = zSql;
+        zSql = sqlite3_mprintf("%s, %s", zTmp, argv[ii]);
+        sqlite3_free(zTmp);
+      }
+      if( zSql ){
+        zTmp = zSql;
+        zSql = sqlite3_mprintf("%s);", zTmp);
+        sqlite3_free(zTmp);
+      }
+      if( !zSql ){
+        rc = SQLITE_NOMEM;
+      }else if( SQLITE_OK!=(rc = sqlite3_declare_vtab(db, zSql)) ){
+        *pzErr = sqlite3_mprintf("%s", sqlite3_errmsg(db));
+      }
+      sqlite3_free(zSql);
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    *ppVtab = (sqlite3_vtab *)pRtree;
+  }else{
+    assert( *ppVtab==0 );
+    assert( pRtree->nBusy==1 );
+    rtreeRelease(pRtree);
+  }
+  return rc;
+}
+
+
+/*
+** Implementation of a scalar function that decodes r-tree nodes to
+** human readable strings. This can be used for debugging and analysis.
+**
+** The scalar function takes two arguments: (1) the number of dimensions
+** to the rtree (between 1 and 5, inclusive) and (2) a blob of data containing
+** an r-tree node.  For a two-dimensional r-tree structure called "rt", to
+** deserialize all nodes, a statement like:
+**
+**   SELECT rtreenode(2, data) FROM rt_node;
+**
+** The human readable string takes the form of a Tcl list with one
+** entry for each cell in the r-tree node. Each entry is itself a
+** list, containing the 8-byte rowid/pageno followed by the 
+** <num-dimension>*2 coordinates.
+*/
+static void rtreenode(sqlite3_context *ctx, int nArg, sqlite3_value **apArg){
+  char *zText = 0;
+  RtreeNode node;
+  Rtree tree;
+  int ii;
+
+  UNUSED_PARAMETER(nArg);
+  memset(&node, 0, sizeof(RtreeNode));
+  memset(&tree, 0, sizeof(Rtree));
+  tree.nDim = sqlite3_value_int(apArg[0]);
+  tree.nBytesPerCell = 8 + 8 * tree.nDim;
+  node.zData = (u8 *)sqlite3_value_blob(apArg[1]);
+
+  for(ii=0; ii<NCELL(&node); ii++){
+    char zCell[512];
+    int nCell = 0;
+    RtreeCell cell;
+    int jj;
+
+    nodeGetCell(&tree, &node, ii, &cell);
+    sqlite3_snprintf(512-nCell,&zCell[nCell],"%lld", cell.iRowid);
+    nCell = (int)strlen(zCell);
+    for(jj=0; jj<tree.nDim*2; jj++){
+#ifndef SQLITE_RTREE_INT_ONLY
+      sqlite3_snprintf(512-nCell,&zCell[nCell], " %g",
+                       (double)cell.aCoord[jj].f);
+#else
+      sqlite3_snprintf(512-nCell,&zCell[nCell], " %d",
+                       cell.aCoord[jj].i);
+#endif
+      nCell = (int)strlen(zCell);
+    }
+
+    if( zText ){
+      char *zTextNew = sqlite3_mprintf("%s {%s}", zText, zCell);
+      sqlite3_free(zText);
+      zText = zTextNew;
+    }else{
+      zText = sqlite3_mprintf("{%s}", zCell);
+    }
+  }
+  
+  sqlite3_result_text(ctx, zText, -1, sqlite3_free);
+}
+
+/* This routine implements an SQL function that returns the "depth" parameter
+** from the front of a blob that is an r-tree node.  For example:
+**
+**     SELECT rtreedepth(data) FROM rt_node WHERE nodeno=1;
+**
+** The depth value is 0 for all nodes other than the root node, and the root
+** node always has nodeno=1, so the example above is the primary use for this
+** routine.  This routine is intended for testing and analysis only.
+*/
+static void rtreedepth(sqlite3_context *ctx, int nArg, sqlite3_value **apArg){
+  UNUSED_PARAMETER(nArg);
+  if( sqlite3_value_type(apArg[0])!=SQLITE_BLOB 
+   || sqlite3_value_bytes(apArg[0])<2
+  ){
+    sqlite3_result_error(ctx, "Invalid argument to rtreedepth()", -1); 
+  }else{
+    u8 *zBlob = (u8 *)sqlite3_value_blob(apArg[0]);
+    sqlite3_result_int(ctx, readInt16(zBlob));
+  }
+}
+
+/*
+** Register the r-tree module with database handle db. This creates the
+** virtual table module "rtree" and the debugging/analysis scalar 
+** function "rtreenode".
+*/
+SQLITE_PRIVATE int sqlite3RtreeInit(sqlite3 *db){
+  const int utf8 = SQLITE_UTF8;
+  int rc;
+
+  rc = sqlite3_create_function(db, "rtreenode", 2, utf8, 0, rtreenode, 0, 0);
+  if( rc==SQLITE_OK ){
+    rc = sqlite3_create_function(db, "rtreedepth", 1, utf8, 0,rtreedepth, 0, 0);
+  }
+  if( rc==SQLITE_OK ){
+#ifdef SQLITE_RTREE_INT_ONLY
+    void *c = (void *)RTREE_COORD_INT32;
+#else
+    void *c = (void *)RTREE_COORD_REAL32;
+#endif
+    rc = sqlite3_create_module_v2(db, "rtree", &rtreeModule, c, 0);
+  }
+  if( rc==SQLITE_OK ){
+    void *c = (void *)RTREE_COORD_INT32;
+    rc = sqlite3_create_module_v2(db, "rtree_i32", &rtreeModule, c, 0);
+  }
+
+  return rc;
+}
+
+/*
+** This routine deletes the RtreeGeomCallback object that was attached
+** one of the SQL functions create by sqlite3_rtree_geometry_callback()
+** or sqlite3_rtree_query_callback().  In other words, this routine is the
+** destructor for an RtreeGeomCallback objecct.  This routine is called when
+** the corresponding SQL function is deleted.
+*/
+static void rtreeFreeCallback(void *p){
+  RtreeGeomCallback *pInfo = (RtreeGeomCallback*)p;
+  if( pInfo->xDestructor ) pInfo->xDestructor(pInfo->pContext);
+  sqlite3_free(p);
+}
+
+/*
+** This routine frees the BLOB that is returned by geomCallback().
+*/
+static void rtreeMatchArgFree(void *pArg){
+  int i;
+  RtreeMatchArg *p = (RtreeMatchArg*)pArg;
+  for(i=0; i<p->nParam; i++){
+    sqlite3_value_free(p->apSqlParam[i]);
+  }
+  sqlite3_free(p);
+}
+
+/*
+** Each call to sqlite3_rtree_geometry_callback() or
+** sqlite3_rtree_query_callback() creates an ordinary SQLite
+** scalar function that is implemented by this routine.
+**
+** All this function does is construct an RtreeMatchArg object that
+** contains the geometry-checking callback routines and a list of
+** parameters to this function, then return that RtreeMatchArg object
+** as a BLOB.
+**
+** The R-Tree MATCH operator will read the returned BLOB, deserialize
+** the RtreeMatchArg object, and use the RtreeMatchArg object to figure
+** out which elements of the R-Tree should be returned by the query.
+*/
+static void geomCallback(sqlite3_context *ctx, int nArg, sqlite3_value **aArg){
+  RtreeGeomCallback *pGeomCtx = (RtreeGeomCallback *)sqlite3_user_data(ctx);
+  RtreeMatchArg *pBlob;
+  int nBlob;
+  int memErr = 0;
+
+  nBlob = sizeof(RtreeMatchArg) + (nArg-1)*sizeof(RtreeDValue)
+           + nArg*sizeof(sqlite3_value*);
+  pBlob = (RtreeMatchArg *)sqlite3_malloc(nBlob);
+  if( !pBlob ){
+    sqlite3_result_error_nomem(ctx);
+  }else{
+    int i;
+    pBlob->magic = RTREE_GEOMETRY_MAGIC;
+    pBlob->cb = pGeomCtx[0];
+    pBlob->apSqlParam = (sqlite3_value**)&pBlob->aParam[nArg];
+    pBlob->nParam = nArg;
+    for(i=0; i<nArg; i++){
+      pBlob->apSqlParam[i] = sqlite3_value_dup(aArg[i]);
+      if( pBlob->apSqlParam[i]==0 ) memErr = 1;
+#ifdef SQLITE_RTREE_INT_ONLY
+      pBlob->aParam[i] = sqlite3_value_int64(aArg[i]);
+#else
+      pBlob->aParam[i] = sqlite3_value_double(aArg[i]);
+#endif
+    }
+    if( memErr ){
+      sqlite3_result_error_nomem(ctx);
+      rtreeMatchArgFree(pBlob);
+    }else{
+      sqlite3_result_blob(ctx, pBlob, nBlob, rtreeMatchArgFree);
+    }
+  }
+}
+
+/*
+** Register a new geometry function for use with the r-tree MATCH operator.
+*/
+SQLITE_API int sqlite3_rtree_geometry_callback(
+  sqlite3 *db,                  /* Register SQL function on this connection */
+  const char *zGeom,            /* Name of the new SQL function */
+  int (*xGeom)(sqlite3_rtree_geometry*,int,RtreeDValue*,int*), /* Callback */
+  void *pContext                /* Extra data associated with the callback */
+){
+  RtreeGeomCallback *pGeomCtx;      /* Context object for new user-function */
+
+  /* Allocate and populate the context object. */
+  pGeomCtx = (RtreeGeomCallback *)sqlite3_malloc(sizeof(RtreeGeomCallback));
+  if( !pGeomCtx ) return SQLITE_NOMEM;
+  pGeomCtx->xGeom = xGeom;
+  pGeomCtx->xQueryFunc = 0;
+  pGeomCtx->xDestructor = 0;
+  pGeomCtx->pContext = pContext;
+  return sqlite3_create_function_v2(db, zGeom, -1, SQLITE_ANY, 
+      (void *)pGeomCtx, geomCallback, 0, 0, rtreeFreeCallback
+  );
+}
+
+/*
+** Register a new 2nd-generation geometry function for use with the
+** r-tree MATCH operator.
+*/
+SQLITE_API int sqlite3_rtree_query_callback(
+  sqlite3 *db,                 /* Register SQL function on this connection */
+  const char *zQueryFunc,      /* Name of new SQL function */
+  int (*xQueryFunc)(sqlite3_rtree_query_info*), /* Callback */
+  void *pContext,              /* Extra data passed into the callback */
+  void (*xDestructor)(void*)   /* Destructor for the extra data */
+){
+  RtreeGeomCallback *pGeomCtx;      /* Context object for new user-function */
+
+  /* Allocate and populate the context object. */
+  pGeomCtx = (RtreeGeomCallback *)sqlite3_malloc(sizeof(RtreeGeomCallback));
+  if( !pGeomCtx ) return SQLITE_NOMEM;
+  pGeomCtx->xGeom = 0;
+  pGeomCtx->xQueryFunc = xQueryFunc;
+  pGeomCtx->xDestructor = xDestructor;
+  pGeomCtx->pContext = pContext;
+  return sqlite3_create_function_v2(db, zQueryFunc, -1, SQLITE_ANY, 
+      (void *)pGeomCtx, geomCallback, 0, 0, rtreeFreeCallback
+  );
+}
+
+#if !SQLITE_CORE
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+SQLITE_API int sqlite3_rtree_init(
+  sqlite3 *db,
+  char **pzErrMsg,
+  const sqlite3_api_routines *pApi
+){
+  SQLITE_EXTENSION_INIT2(pApi)
+  return sqlite3RtreeInit(db);
+}
+#endif
+
+#endif
+
+/************** End of rtree.c ***********************************************/
+/************** Begin file icu.c *********************************************/
+/*
+** 2007 May 6
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** $Id: icu.c,v 1.7 2007/12/13 21:54:11 drh Exp $
+**
+** This file implements an integration between the ICU library 
+** ("International Components for Unicode", an open-source library 
+** for handling unicode data) and SQLite. The integration uses 
+** ICU to provide the following to SQLite:
+**
+**   * An implementation of the SQL regexp() function (and hence REGEXP
+**     operator) using the ICU uregex_XX() APIs.
+**
+**   * Implementations of the SQL scalar upper() and lower() functions
+**     for case mapping.
+**
+**   * Integration of ICU and SQLite collation sequences.
+**
+**   * An implementation of the LIKE operator that uses ICU to 
+**     provide case-independent matching.
+*/
+
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_ICU)
+
+/* Include ICU headers */
+#include <unicode/utypes.h>
+#include <unicode/uregex.h>
+#include <unicode/ustring.h>
+#include <unicode/ucol.h>
+
+/* #include <assert.h> */
+
+#ifndef SQLITE_CORE
+/*   #include "sqlite3ext.h" */
+  SQLITE_EXTENSION_INIT1
+#else
+/*   #include "sqlite3.h" */
+#endif
+
+/*
+** Maximum length (in bytes) of the pattern in a LIKE or GLOB
+** operator.
+*/
+#ifndef SQLITE_MAX_LIKE_PATTERN_LENGTH
+# define SQLITE_MAX_LIKE_PATTERN_LENGTH 50000
+#endif
+
+/*
+** Version of sqlite3_free() that is always a function, never a macro.
+*/
+static void xFree(void *p){
+  sqlite3_free(p);
+}
+
+/*
+** This lookup table is used to help decode the first byte of
+** a multi-byte UTF8 character. It is copied here from SQLite source
+** code file utf8.c.
+*/
+static const unsigned char icuUtf8Trans1[] = {
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+  0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+  0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x00, 0x01, 0x02, 0x03, 0x00, 0x01, 0x00, 0x00,
+};
+
+#define SQLITE_ICU_READ_UTF8(zIn, c)                       \
+  c = *(zIn++);                                            \
+  if( c>=0xc0 ){                                           \
+    c = icuUtf8Trans1[c-0xc0];                             \
+    while( (*zIn & 0xc0)==0x80 ){                          \
+      c = (c<<6) + (0x3f & *(zIn++));                      \
+    }                                                      \
+  }
+
+#define SQLITE_ICU_SKIP_UTF8(zIn)                          \
+  assert( *zIn );                                          \
+  if( *(zIn++)>=0xc0 ){                                    \
+    while( (*zIn & 0xc0)==0x80 ){zIn++;}                   \
+  }
+
+
+/*
+** Compare two UTF-8 strings for equality where the first string is
+** a "LIKE" expression. Return true (1) if they are the same and 
+** false (0) if they are different.
+*/
+static int icuLikeCompare(
+  const uint8_t *zPattern,   /* LIKE pattern */
+  const uint8_t *zString,    /* The UTF-8 string to compare against */
+  const UChar32 uEsc         /* The escape character */
+){
+  static const int MATCH_ONE = (UChar32)'_';
+  static const int MATCH_ALL = (UChar32)'%';
+
+  int prevEscape = 0;     /* True if the previous character was uEsc */
+
+  while( 1 ){
+
+    /* Read (and consume) the next character from the input pattern. */
+    UChar32 uPattern;
+    SQLITE_ICU_READ_UTF8(zPattern, uPattern);
+    if( uPattern==0 ) break;
+
+    /* There are now 4 possibilities:
+    **
+    **     1. uPattern is an unescaped match-all character "%",
+    **     2. uPattern is an unescaped match-one character "_",
+    **     3. uPattern is an unescaped escape character, or
+    **     4. uPattern is to be handled as an ordinary character
+    */
+    if( !prevEscape && uPattern==MATCH_ALL ){
+      /* Case 1. */
+      uint8_t c;
+
+      /* Skip any MATCH_ALL or MATCH_ONE characters that follow a
+      ** MATCH_ALL. For each MATCH_ONE, skip one character in the 
+      ** test string.
+      */
+      while( (c=*zPattern) == MATCH_ALL || c == MATCH_ONE ){
+        if( c==MATCH_ONE ){
+          if( *zString==0 ) return 0;
+          SQLITE_ICU_SKIP_UTF8(zString);
+        }
+        zPattern++;
+      }
+
+      if( *zPattern==0 ) return 1;
+
+      while( *zString ){
+        if( icuLikeCompare(zPattern, zString, uEsc) ){
+          return 1;
+        }
+        SQLITE_ICU_SKIP_UTF8(zString);
+      }
+      return 0;
+
+    }else if( !prevEscape && uPattern==MATCH_ONE ){
+      /* Case 2. */
+      if( *zString==0 ) return 0;
+      SQLITE_ICU_SKIP_UTF8(zString);
+
+    }else if( !prevEscape && uPattern==uEsc){
+      /* Case 3. */
+      prevEscape = 1;
+
+    }else{
+      /* Case 4. */
+      UChar32 uString;
+      SQLITE_ICU_READ_UTF8(zString, uString);
+      uString = u_foldCase(uString, U_FOLD_CASE_DEFAULT);
+      uPattern = u_foldCase(uPattern, U_FOLD_CASE_DEFAULT);
+      if( uString!=uPattern ){
+        return 0;
+      }
+      prevEscape = 0;
+    }
+  }
+
+  return *zString==0;
+}
+
+/*
+** Implementation of the like() SQL function.  This function implements
+** the build-in LIKE operator.  The first argument to the function is the
+** pattern and the second argument is the string.  So, the SQL statements:
+**
+**       A LIKE B
+**
+** is implemented as like(B, A). If there is an escape character E, 
+**
+**       A LIKE B ESCAPE E
+**
+** is mapped to like(B, A, E).
+*/
+static void icuLikeFunc(
+  sqlite3_context *context, 
+  int argc, 
+  sqlite3_value **argv
+){
+  const unsigned char *zA = sqlite3_value_text(argv[0]);
+  const unsigned char *zB = sqlite3_value_text(argv[1]);
+  UChar32 uEsc = 0;
+
+  /* Limit the length of the LIKE or GLOB pattern to avoid problems
+  ** of deep recursion and N*N behavior in patternCompare().
+  */
+  if( sqlite3_value_bytes(argv[0])>SQLITE_MAX_LIKE_PATTERN_LENGTH ){
+    sqlite3_result_error(context, "LIKE or GLOB pattern too complex", -1);
+    return;
+  }
+
+
+  if( argc==3 ){
+    /* The escape character string must consist of a single UTF-8 character.
+    ** Otherwise, return an error.
+    */
+    int nE= sqlite3_value_bytes(argv[2]);
+    const unsigned char *zE = sqlite3_value_text(argv[2]);
+    int i = 0;
+    if( zE==0 ) return;
+    U8_NEXT(zE, i, nE, uEsc);
+    if( i!=nE){
+      sqlite3_result_error(context, 
+          "ESCAPE expression must be a single character", -1);
+      return;
+    }
+  }
+
+  if( zA && zB ){
+    sqlite3_result_int(context, icuLikeCompare(zA, zB, uEsc));
+  }
+}
+
+/*
+** This function is called when an ICU function called from within
+** the implementation of an SQL scalar function returns an error.
+**
+** The scalar function context passed as the first argument is 
+** loaded with an error message based on the following two args.
+*/
+static void icuFunctionError(
+  sqlite3_context *pCtx,       /* SQLite scalar function context */
+  const char *zName,           /* Name of ICU function that failed */
+  UErrorCode e                 /* Error code returned by ICU function */
+){
+  char zBuf[128];
+  sqlite3_snprintf(128, zBuf, "ICU error: %s(): %s", zName, u_errorName(e));
+  zBuf[127] = '\0';
+  sqlite3_result_error(pCtx, zBuf, -1);
+}
+
+/*
+** Function to delete compiled regexp objects. Registered as
+** a destructor function with sqlite3_set_auxdata().
+*/
+static void icuRegexpDelete(void *p){
+  URegularExpression *pExpr = (URegularExpression *)p;
+  uregex_close(pExpr);
+}
+
+/*
+** Implementation of SQLite REGEXP operator. This scalar function takes
+** two arguments. The first is a regular expression pattern to compile
+** the second is a string to match against that pattern. If either 
+** argument is an SQL NULL, then NULL Is returned. Otherwise, the result
+** is 1 if the string matches the pattern, or 0 otherwise.
+**
+** SQLite maps the regexp() function to the regexp() operator such
+** that the following two are equivalent:
+**
+**     zString REGEXP zPattern
+**     regexp(zPattern, zString)
+**
+** Uses the following ICU regexp APIs:
+**
+**     uregex_open()
+**     uregex_matches()
+**     uregex_close()
+*/
+static void icuRegexpFunc(sqlite3_context *p, int nArg, sqlite3_value **apArg){
+  UErrorCode status = U_ZERO_ERROR;
+  URegularExpression *pExpr;
+  UBool res;
+  const UChar *zString = sqlite3_value_text16(apArg[1]);
+
+  (void)nArg;  /* Unused parameter */
+
+  /* If the left hand side of the regexp operator is NULL, 
+  ** then the result is also NULL. 
+  */
+  if( !zString ){
+    return;
+  }
+
+  pExpr = sqlite3_get_auxdata(p, 0);
+  if( !pExpr ){
+    const UChar *zPattern = sqlite3_value_text16(apArg[0]);
+    if( !zPattern ){
+      return;
+    }
+    pExpr = uregex_open(zPattern, -1, 0, 0, &status);
+
+    if( U_SUCCESS(status) ){
+      sqlite3_set_auxdata(p, 0, pExpr, icuRegexpDelete);
+    }else{
+      assert(!pExpr);
+      icuFunctionError(p, "uregex_open", status);
+      return;
+    }
+  }
+
+  /* Configure the text that the regular expression operates on. */
+  uregex_setText(pExpr, zString, -1, &status);
+  if( !U_SUCCESS(status) ){
+    icuFunctionError(p, "uregex_setText", status);
+    return;
+  }
+
+  /* Attempt the match */
+  res = uregex_matches(pExpr, 0, &status);
+  if( !U_SUCCESS(status) ){
+    icuFunctionError(p, "uregex_matches", status);
+    return;
+  }
+
+  /* Set the text that the regular expression operates on to a NULL
+  ** pointer. This is not really necessary, but it is tidier than 
+  ** leaving the regular expression object configured with an invalid
+  ** pointer after this function returns.
+  */
+  uregex_setText(pExpr, 0, 0, &status);
+
+  /* Return 1 or 0. */
+  sqlite3_result_int(p, res ? 1 : 0);
+}
+
+/*
+** Implementations of scalar functions for case mapping - upper() and 
+** lower(). Function upper() converts its input to upper-case (ABC).
+** Function lower() converts to lower-case (abc).
+**
+** ICU provides two types of case mapping, "general" case mapping and
+** "language specific". Refer to ICU documentation for the differences
+** between the two.
+**
+** To utilise "general" case mapping, the upper() or lower() scalar 
+** functions are invoked with one argument:
+**
+**     upper('ABC') -> 'abc'
+**     lower('abc') -> 'ABC'
+**
+** To access ICU "language specific" case mapping, upper() or lower()
+** should be invoked with two arguments. The second argument is the name
+** of the locale to use. Passing an empty string ("") or SQL NULL value
+** as the second argument is the same as invoking the 1 argument version
+** of upper() or lower().
+**
+**     lower('I', 'en_us') -> 'i'
+**     lower('I', 'tr_tr') -> '\u131' (small dotless i)
+**
+** http://www.icu-project.org/userguide/posix.html#case_mappings
+*/
+static void icuCaseFunc16(sqlite3_context *p, int nArg, sqlite3_value **apArg){
+  const UChar *zInput;            /* Pointer to input string */
+  UChar *zOutput = 0;             /* Pointer to output buffer */
+  int nInput;                     /* Size of utf-16 input string in bytes */
+  int nOut;                       /* Size of output buffer in bytes */
+  int cnt;
+  int bToUpper;                   /* True for toupper(), false for tolower() */
+  UErrorCode status;
+  const char *zLocale = 0;
+
+  assert(nArg==1 || nArg==2);
+  bToUpper = (sqlite3_user_data(p)!=0);
+  if( nArg==2 ){
+    zLocale = (const char *)sqlite3_value_text(apArg[1]);
+  }
+
+  zInput = sqlite3_value_text16(apArg[0]);
+  if( !zInput ){
+    return;
+  }
+  nOut = nInput = sqlite3_value_bytes16(apArg[0]);
+  if( nOut==0 ){
+    sqlite3_result_text16(p, "", 0, SQLITE_STATIC);
+    return;
+  }
+
+  for(cnt=0; cnt<2; cnt++){
+    UChar *zNew = sqlite3_realloc(zOutput, nOut);
+    if( zNew==0 ){
+      sqlite3_free(zOutput);
+      sqlite3_result_error_nomem(p);
+      return;
+    }
+    zOutput = zNew;
+    status = U_ZERO_ERROR;
+    if( bToUpper ){
+      nOut = 2*u_strToUpper(zOutput,nOut/2,zInput,nInput/2,zLocale,&status);
+    }else{
+      nOut = 2*u_strToLower(zOutput,nOut/2,zInput,nInput/2,zLocale,&status);
+    }
+
+    if( U_SUCCESS(status) ){
+      sqlite3_result_text16(p, zOutput, nOut, xFree);
+    }else if( status==U_BUFFER_OVERFLOW_ERROR ){
+      assert( cnt==0 );
+      continue;
+    }else{
+      icuFunctionError(p, bToUpper ? "u_strToUpper" : "u_strToLower", status);
+    }
+    return;
+  }
+  assert( 0 );     /* Unreachable */
+}
+
+/*
+** Collation sequence destructor function. The pCtx argument points to
+** a UCollator structure previously allocated using ucol_open().
+*/
+static void icuCollationDel(void *pCtx){
+  UCollator *p = (UCollator *)pCtx;
+  ucol_close(p);
+}
+
+/*
+** Collation sequence comparison function. The pCtx argument points to
+** a UCollator structure previously allocated using ucol_open().
+*/
+static int icuCollationColl(
+  void *pCtx,
+  int nLeft,
+  const void *zLeft,
+  int nRight,
+  const void *zRight
+){
+  UCollationResult res;
+  UCollator *p = (UCollator *)pCtx;
+  res = ucol_strcoll(p, (UChar *)zLeft, nLeft/2, (UChar *)zRight, nRight/2);
+  switch( res ){
+    case UCOL_LESS:    return -1;
+    case UCOL_GREATER: return +1;
+    case UCOL_EQUAL:   return 0;
+  }
+  assert(!"Unexpected return value from ucol_strcoll()");
+  return 0;
+}
+
+/*
+** Implementation of the scalar function icu_load_collation().
+**
+** This scalar function is used to add ICU collation based collation 
+** types to an SQLite database connection. It is intended to be called
+** as follows:
+**
+**     SELECT icu_load_collation(<locale>, <collation-name>);
+**
+** Where <locale> is a string containing an ICU locale identifier (i.e.
+** "en_AU", "tr_TR" etc.) and <collation-name> is the name of the
+** collation sequence to create.
+*/
+static void icuLoadCollation(
+  sqlite3_context *p, 
+  int nArg, 
+  sqlite3_value **apArg
+){
+  sqlite3 *db = (sqlite3 *)sqlite3_user_data(p);
+  UErrorCode status = U_ZERO_ERROR;
+  const char *zLocale;      /* Locale identifier - (eg. "jp_JP") */
+  const char *zName;        /* SQL Collation sequence name (eg. "japanese") */
+  UCollator *pUCollator;    /* ICU library collation object */
+  int rc;                   /* Return code from sqlite3_create_collation_x() */
+
+  assert(nArg==2);
+  (void)nArg; /* Unused parameter */
+  zLocale = (const char *)sqlite3_value_text(apArg[0]);
+  zName = (const char *)sqlite3_value_text(apArg[1]);
+
+  if( !zLocale || !zName ){
+    return;
+  }
+
+  pUCollator = ucol_open(zLocale, &status);
+  if( !U_SUCCESS(status) ){
+    icuFunctionError(p, "ucol_open", status);
+    return;
+  }
+  assert(p);
+
+  rc = sqlite3_create_collation_v2(db, zName, SQLITE_UTF16, (void *)pUCollator, 
+      icuCollationColl, icuCollationDel
+  );
+  if( rc!=SQLITE_OK ){
+    ucol_close(pUCollator);
+    sqlite3_result_error(p, "Error registering collation function", -1);
+  }
+}
+
+/*
+** Register the ICU extension functions with database db.
+*/
+SQLITE_PRIVATE int sqlite3IcuInit(sqlite3 *db){
+  struct IcuScalar {
+    const char *zName;                        /* Function name */
+    int nArg;                                 /* Number of arguments */
+    int enc;                                  /* Optimal text encoding */
+    void *pContext;                           /* sqlite3_user_data() context */
+    void (*xFunc)(sqlite3_context*,int,sqlite3_value**);
+  } scalars[] = {
+    {"regexp", 2, SQLITE_ANY|SQLITE_DETERMINISTIC,          0, icuRegexpFunc},
+
+    {"lower",  1, SQLITE_UTF16|SQLITE_DETERMINISTIC,        0, icuCaseFunc16},
+    {"lower",  2, SQLITE_UTF16|SQLITE_DETERMINISTIC,        0, icuCaseFunc16},
+    {"upper",  1, SQLITE_UTF16|SQLITE_DETERMINISTIC, (void*)1, icuCaseFunc16},
+    {"upper",  2, SQLITE_UTF16|SQLITE_DETERMINISTIC, (void*)1, icuCaseFunc16},
+
+    {"lower",  1, SQLITE_UTF8|SQLITE_DETERMINISTIC,         0, icuCaseFunc16},
+    {"lower",  2, SQLITE_UTF8|SQLITE_DETERMINISTIC,         0, icuCaseFunc16},
+    {"upper",  1, SQLITE_UTF8|SQLITE_DETERMINISTIC,  (void*)1, icuCaseFunc16},
+    {"upper",  2, SQLITE_UTF8|SQLITE_DETERMINISTIC,  (void*)1, icuCaseFunc16},
+
+    {"like",   2, SQLITE_UTF8|SQLITE_DETERMINISTIC,         0, icuLikeFunc},
+    {"like",   3, SQLITE_UTF8|SQLITE_DETERMINISTIC,         0, icuLikeFunc},
+
+    {"icu_load_collation",  2, SQLITE_UTF8, (void*)db, icuLoadCollation},
+  };
+
+  int rc = SQLITE_OK;
+  int i;
+
+  for(i=0; rc==SQLITE_OK && i<(int)(sizeof(scalars)/sizeof(scalars[0])); i++){
+    struct IcuScalar *p = &scalars[i];
+    rc = sqlite3_create_function(
+        db, p->zName, p->nArg, p->enc, p->pContext, p->xFunc, 0, 0
+    );
+  }
+
+  return rc;
+}
+
+#if !SQLITE_CORE
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+SQLITE_API int sqlite3_icu_init(
+  sqlite3 *db, 
+  char **pzErrMsg,
+  const sqlite3_api_routines *pApi
+){
+  SQLITE_EXTENSION_INIT2(pApi)
+  return sqlite3IcuInit(db);
+}
+#endif
+
+#endif
+
+/************** End of icu.c *************************************************/
+/************** Begin file fts3_icu.c ****************************************/
+/*
+** 2007 June 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file implements a tokenizer for fts3 based on the ICU library.
+*/
+/* #include "fts3Int.h" */
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
+#ifdef SQLITE_ENABLE_ICU
+
+/* #include <assert.h> */
+/* #include <string.h> */
+/* #include "fts3_tokenizer.h" */
+
+#include <unicode/ubrk.h>
+/* #include <unicode/ucol.h> */
+/* #include <unicode/ustring.h> */
+#include <unicode/utf16.h>
+
+typedef struct IcuTokenizer IcuTokenizer;
+typedef struct IcuCursor IcuCursor;
+
+struct IcuTokenizer {
+  sqlite3_tokenizer base;
+  char *zLocale;
+};
+
+struct IcuCursor {
+  sqlite3_tokenizer_cursor base;
+
+  UBreakIterator *pIter;      /* ICU break-iterator object */
+  int nChar;                  /* Number of UChar elements in pInput */
+  UChar *aChar;               /* Copy of input using utf-16 encoding */
+  int *aOffset;               /* Offsets of each character in utf-8 input */
+
+  int nBuffer;
+  char *zBuffer;
+
+  int iToken;
+};
+
+/*
+** Create a new tokenizer instance.
+*/
+static int icuCreate(
+  int argc,                            /* Number of entries in argv[] */
+  const char * const *argv,            /* Tokenizer creation arguments */
+  sqlite3_tokenizer **ppTokenizer      /* OUT: Created tokenizer */
+){
+  IcuTokenizer *p;
+  int n = 0;
+
+  if( argc>0 ){
+    n = strlen(argv[0])+1;
+  }
+  p = (IcuTokenizer *)sqlite3_malloc(sizeof(IcuTokenizer)+n);
+  if( !p ){
+    return SQLITE_NOMEM;
+  }
+  memset(p, 0, sizeof(IcuTokenizer));
+
+  if( n ){
+    p->zLocale = (char *)&p[1];
+    memcpy(p->zLocale, argv[0], n);
+  }
+
+  *ppTokenizer = (sqlite3_tokenizer *)p;
+
+  return SQLITE_OK;
+}
+
+/*
+** Destroy a tokenizer
+*/
+static int icuDestroy(sqlite3_tokenizer *pTokenizer){
+  IcuTokenizer *p = (IcuTokenizer *)pTokenizer;
+  sqlite3_free(p);
+  return SQLITE_OK;
+}
+
+/*
+** Prepare to begin tokenizing a particular string.  The input
+** string to be tokenized is pInput[0..nBytes-1].  A cursor
+** used to incrementally tokenize this string is returned in 
+** *ppCursor.
+*/
+static int icuOpen(
+  sqlite3_tokenizer *pTokenizer,         /* The tokenizer */
+  const char *zInput,                    /* Input string */
+  int nInput,                            /* Length of zInput in bytes */
+  sqlite3_tokenizer_cursor **ppCursor    /* OUT: Tokenization cursor */
+){
+  IcuTokenizer *p = (IcuTokenizer *)pTokenizer;
+  IcuCursor *pCsr;
+
+  const int32_t opt = U_FOLD_CASE_DEFAULT;
+  UErrorCode status = U_ZERO_ERROR;
+  int nChar;
+
+  UChar32 c;
+  int iInput = 0;
+  int iOut = 0;
+
+  *ppCursor = 0;
+
+  if( zInput==0 ){
+    nInput = 0;
+    zInput = "";
+  }else if( nInput<0 ){
+    nInput = strlen(zInput);
+  }
+  nChar = nInput+1;
+  pCsr = (IcuCursor *)sqlite3_malloc(
+      sizeof(IcuCursor) +                /* IcuCursor */
+      ((nChar+3)&~3) * sizeof(UChar) +   /* IcuCursor.aChar[] */
+      (nChar+1) * sizeof(int)            /* IcuCursor.aOffset[] */
+  );
+  if( !pCsr ){
+    return SQLITE_NOMEM;
+  }
+  memset(pCsr, 0, sizeof(IcuCursor));
+  pCsr->aChar = (UChar *)&pCsr[1];
+  pCsr->aOffset = (int *)&pCsr->aChar[(nChar+3)&~3];
+
+  pCsr->aOffset[iOut] = iInput;
+  U8_NEXT(zInput, iInput, nInput, c); 
+  while( c>0 ){
+    int isError = 0;
+    c = u_foldCase(c, opt);
+    U16_APPEND(pCsr->aChar, iOut, nChar, c, isError);
+    if( isError ){
+      sqlite3_free(pCsr);
+      return SQLITE_ERROR;
+    }
+    pCsr->aOffset[iOut] = iInput;
+
+    if( iInput<nInput ){
+      U8_NEXT(zInput, iInput, nInput, c);
+    }else{
+      c = 0;
+    }
+  }
+
+  pCsr->pIter = ubrk_open(UBRK_WORD, p->zLocale, pCsr->aChar, iOut, &status);
+  if( !U_SUCCESS(status) ){
+    sqlite3_free(pCsr);
+    return SQLITE_ERROR;
+  }
+  pCsr->nChar = iOut;
+
+  ubrk_first(pCsr->pIter);
+  *ppCursor = (sqlite3_tokenizer_cursor *)pCsr;
+  return SQLITE_OK;
+}
+
+/*
+** Close a tokenization cursor previously opened by a call to icuOpen().
+*/
+static int icuClose(sqlite3_tokenizer_cursor *pCursor){
+  IcuCursor *pCsr = (IcuCursor *)pCursor;
+  ubrk_close(pCsr->pIter);
+  sqlite3_free(pCsr->zBuffer);
+  sqlite3_free(pCsr);
+  return SQLITE_OK;
+}
+
+/*
+** Extract the next token from a tokenization cursor.
+*/
+static int icuNext(
+  sqlite3_tokenizer_cursor *pCursor,  /* Cursor returned by simpleOpen */
+  const char **ppToken,               /* OUT: *ppToken is the token text */
+  int *pnBytes,                       /* OUT: Number of bytes in token */
+  int *piStartOffset,                 /* OUT: Starting offset of token */
+  int *piEndOffset,                   /* OUT: Ending offset of token */
+  int *piPosition                     /* OUT: Position integer of token */
+){
+  IcuCursor *pCsr = (IcuCursor *)pCursor;
+
+  int iStart = 0;
+  int iEnd = 0;
+  int nByte = 0;
+
+  while( iStart==iEnd ){
+    UChar32 c;
+
+    iStart = ubrk_current(pCsr->pIter);
+    iEnd = ubrk_next(pCsr->pIter);
+    if( iEnd==UBRK_DONE ){
+      return SQLITE_DONE;
+    }
+
+    while( iStart<iEnd ){
+      int iWhite = iStart;
+      U16_NEXT(pCsr->aChar, iWhite, pCsr->nChar, c);
+      if( u_isspace(c) ){
+        iStart = iWhite;
+      }else{
+        break;
+      }
+    }
+    assert(iStart<=iEnd);
+  }
+
+  do {
+    UErrorCode status = U_ZERO_ERROR;
+    if( nByte ){
+      char *zNew = sqlite3_realloc(pCsr->zBuffer, nByte);
+      if( !zNew ){
+        return SQLITE_NOMEM;
+      }
+      pCsr->zBuffer = zNew;
+      pCsr->nBuffer = nByte;
+    }
+
+    u_strToUTF8(
+        pCsr->zBuffer, pCsr->nBuffer, &nByte,    /* Output vars */
+        &pCsr->aChar[iStart], iEnd-iStart,       /* Input vars */
+        &status                                  /* Output success/failure */
+    );
+  } while( nByte>pCsr->nBuffer );
+
+  *ppToken = pCsr->zBuffer;
+  *pnBytes = nByte;
+  *piStartOffset = pCsr->aOffset[iStart];
+  *piEndOffset = pCsr->aOffset[iEnd];
+  *piPosition = pCsr->iToken++;
+
+  return SQLITE_OK;
+}
+
+/*
+** The set of routines that implement the simple tokenizer
+*/
+static const sqlite3_tokenizer_module icuTokenizerModule = {
+  0,                           /* iVersion    */
+  icuCreate,                   /* xCreate     */
+  icuDestroy,                  /* xCreate     */
+  icuOpen,                     /* xOpen       */
+  icuClose,                    /* xClose      */
+  icuNext,                     /* xNext       */
+  0,                           /* xLanguageid */
+};
+
+/*
+** Set *ppModule to point at the implementation of the ICU tokenizer.
+*/
+SQLITE_PRIVATE void sqlite3Fts3IcuTokenizerModule(
+  sqlite3_tokenizer_module const**ppModule
+){
+  *ppModule = &icuTokenizerModule;
+}
+
+#endif /* defined(SQLITE_ENABLE_ICU) */
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */
+
+/************** End of fts3_icu.c ********************************************/
+/************** Begin file sqlite3rbu.c **************************************/
+/*
+** 2014 August 30
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+**
+** OVERVIEW 
+**
+**  The RBU extension requires that the RBU update be packaged as an
+**  SQLite database. The tables it expects to find are described in
+**  sqlite3rbu.h.  Essentially, for each table xyz in the target database
+**  that the user wishes to write to, a corresponding data_xyz table is
+**  created in the RBU database and populated with one row for each row to
+**  update, insert or delete from the target table.
+** 
+**  The update proceeds in three stages:
+** 
+**  1) The database is updated. The modified database pages are written
+**     to a *-oal file. A *-oal file is just like a *-wal file, except
+**     that it is named "<database>-oal" instead of "<database>-wal".
+**     Because regular SQLite clients do not look for file named
+**     "<database>-oal", they go on using the original database in
+**     rollback mode while the *-oal file is being generated.
+** 
+**     During this stage RBU does not update the database by writing
+**     directly to the target tables. Instead it creates "imposter"
+**     tables using the SQLITE_TESTCTRL_IMPOSTER interface that it uses
+**     to update each b-tree individually. All updates required by each
+**     b-tree are completed before moving on to the next, and all
+**     updates are done in sorted key order.
+** 
+**  2) The "<database>-oal" file is moved to the equivalent "<database>-wal"
+**     location using a call to rename(2). Before doing this the RBU
+**     module takes an EXCLUSIVE lock on the database file, ensuring
+**     that there are no other active readers.
+** 
+**     Once the EXCLUSIVE lock is released, any other database readers
+**     detect the new *-wal file and read the database in wal mode. At
+**     this point they see the new version of the database - including
+**     the updates made as part of the RBU update.
+** 
+**  3) The new *-wal file is checkpointed. This proceeds in the same way 
+**     as a regular database checkpoint, except that a single frame is
+**     checkpointed each time sqlite3rbu_step() is called. If the RBU
+**     handle is closed before the entire *-wal file is checkpointed,
+**     the checkpoint progress is saved in the RBU database and the
+**     checkpoint can be resumed by another RBU client at some point in
+**     the future.
+**
+** POTENTIAL PROBLEMS
+** 
+**  The rename() call might not be portable. And RBU is not currently
+**  syncing the directory after renaming the file.
+**
+**  When state is saved, any commit to the *-oal file and the commit to
+**  the RBU update database are not atomic. So if the power fails at the
+**  wrong moment they might get out of sync. As the main database will be
+**  committed before the RBU update database this will likely either just
+**  pass unnoticed, or result in SQLITE_CONSTRAINT errors (due to UNIQUE
+**  constraint violations).
+**
+**  If some client does modify the target database mid RBU update, or some
+**  other error occurs, the RBU extension will keep throwing errors. It's
+**  not really clear how to get out of this state. The system could just
+**  by delete the RBU update database and *-oal file and have the device
+**  download the update again and start over.
+**
+**  At present, for an UPDATE, both the new.* and old.* records are
+**  collected in the rbu_xyz table. And for both UPDATEs and DELETEs all
+**  fields are collected.  This means we're probably writing a lot more
+**  data to disk when saving the state of an ongoing update to the RBU
+**  update database than is strictly necessary.
+** 
+*/
+
+/* #include <assert.h> */
+/* #include <string.h> */
+/* #include <stdio.h> */
+
+/* #include "sqlite3.h" */
+
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_RBU)
+/************** Include sqlite3rbu.h in the middle of sqlite3rbu.c ***********/
+/************** Begin file sqlite3rbu.h **************************************/
+/*
+** 2014 August 30
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains the public interface for the RBU extension. 
+*/
+
+/*
+** SUMMARY
+**
+** Writing a transaction containing a large number of operations on 
+** b-tree indexes that are collectively larger than the available cache
+** memory can be very inefficient. 
+**
+** The problem is that in order to update a b-tree, the leaf page (at least)
+** containing the entry being inserted or deleted must be modified. If the
+** working set of leaves is larger than the available cache memory, then a 
+** single leaf that is modified more than once as part of the transaction 
+** may be loaded from or written to the persistent media multiple times.
+** Additionally, because the index updates are likely to be applied in
+** random order, access to pages within the database is also likely to be in 
+** random order, which is itself quite inefficient.
+**
+** One way to improve the situation is to sort the operations on each index
+** by index key before applying them to the b-tree. This leads to an IO
+** pattern that resembles a single linear scan through the index b-tree,
+** and all but guarantees each modified leaf page is loaded and stored 
+** exactly once. SQLite uses this trick to improve the performance of
+** CREATE INDEX commands. This extension allows it to be used to improve
+** the performance of large transactions on existing databases.
+**
+** Additionally, this extension allows the work involved in writing the 
+** large transaction to be broken down into sub-transactions performed 
+** sequentially by separate processes. This is useful if the system cannot 
+** guarantee that a single update process will run for long enough to apply 
+** the entire update, for example because the update is being applied on a 
+** mobile device that is frequently rebooted. Even after the writer process 
+** has committed one or more sub-transactions, other database clients continue
+** to read from the original database snapshot. In other words, partially 
+** applied transactions are not visible to other clients. 
+**
+** "RBU" stands for "Resumable Bulk Update". As in a large database update
+** transmitted via a wireless network to a mobile device. A transaction
+** applied using this extension is hence refered to as an "RBU update".
+**
+**
+** LIMITATIONS
+**
+** An "RBU update" transaction is subject to the following limitations:
+**
+**   * The transaction must consist of INSERT, UPDATE and DELETE operations
+**     only.
+**
+**   * INSERT statements may not use any default values.
+**
+**   * UPDATE and DELETE statements must identify their target rows by 
+**     non-NULL PRIMARY KEY values. Rows with NULL values stored in PRIMARY
+**     KEY fields may not be updated or deleted. If the table being written 
+**     has no PRIMARY KEY, affected rows must be identified by rowid.
+**
+**   * UPDATE statements may not modify PRIMARY KEY columns.
+**
+**   * No triggers will be fired.
+**
+**   * No foreign key violations are detected or reported.
+**
+**   * CHECK constraints are not enforced.
+**
+**   * No constraint handling mode except for "OR ROLLBACK" is supported.
+**
+**
+** PREPARATION
+**
+** An "RBU update" is stored as a separate SQLite database. A database
+** containing an RBU update is an "RBU database". For each table in the 
+** target database to be updated, the RBU database should contain a table
+** named "data_<target name>" containing the same set of columns as the
+** target table, and one more - "rbu_control". The data_% table should 
+** have no PRIMARY KEY or UNIQUE constraints, but each column should have
+** the same type as the corresponding column in the target database.
+** The "rbu_control" column should have no type at all. For example, if
+** the target database contains:
+**
+**   CREATE TABLE t1(a INTEGER PRIMARY KEY, b TEXT, c UNIQUE);
+**
+** Then the RBU database should contain:
+**
+**   CREATE TABLE data_t1(a INTEGER, b TEXT, c, rbu_control);
+**
+** The order of the columns in the data_% table does not matter.
+**
+** Instead of a regular table, the RBU database may also contain virtual
+** tables or view named using the data_<target> naming scheme. 
+**
+** Instead of the plain data_<target> naming scheme, RBU database tables 
+** may also be named data<integer>_<target>, where <integer> is any sequence
+** of zero or more numeric characters (0-9). This can be significant because
+** tables within the RBU database are always processed in order sorted by 
+** name. By judicious selection of the <integer> portion of the names
+** of the RBU tables the user can therefore control the order in which they
+** are processed. This can be useful, for example, to ensure that "external
+** content" FTS4 tables are updated before their underlying content tables.
+**
+** If the target database table is a virtual table or a table that has no
+** PRIMARY KEY declaration, the data_% table must also contain a column 
+** named "rbu_rowid". This column is mapped to the tables implicit primary 
+** key column - "rowid". Virtual tables for which the "rowid" column does 
+** not function like a primary key value cannot be updated using RBU. For 
+** example, if the target db contains either of the following:
+**
+**   CREATE VIRTUAL TABLE x1 USING fts3(a, b);
+**   CREATE TABLE x1(a, b)
+**
+** then the RBU database should contain:
+**
+**   CREATE TABLE data_x1(a, b, rbu_rowid, rbu_control);
+**
+** All non-hidden columns (i.e. all columns matched by "SELECT *") of the
+** target table must be present in the input table. For virtual tables,
+** hidden columns are optional - they are updated by RBU if present in
+** the input table, or not otherwise. For example, to write to an fts4
+** table with a hidden languageid column such as:
+**
+**   CREATE VIRTUAL TABLE ft1 USING fts4(a, b, languageid='langid');
+**
+** Either of the following input table schemas may be used:
+**
+**   CREATE TABLE data_ft1(a, b, langid, rbu_rowid, rbu_control);
+**   CREATE TABLE data_ft1(a, b, rbu_rowid, rbu_control);
+**
+** For each row to INSERT into the target database as part of the RBU 
+** update, the corresponding data_% table should contain a single record
+** with the "rbu_control" column set to contain integer value 0. The
+** other columns should be set to the values that make up the new record 
+** to insert. 
+**
+** If the target database table has an INTEGER PRIMARY KEY, it is not 
+** possible to insert a NULL value into the IPK column. Attempting to 
+** do so results in an SQLITE_MISMATCH error.
+**
+** For each row to DELETE from the target database as part of the RBU 
+** update, the corresponding data_% table should contain a single record
+** with the "rbu_control" column set to contain integer value 1. The
+** real primary key values of the row to delete should be stored in the
+** corresponding columns of the data_% table. The values stored in the
+** other columns are not used.
+**
+** For each row to UPDATE from the target database as part of the RBU 
+** update, the corresponding data_% table should contain a single record
+** with the "rbu_control" column set to contain a value of type text.
+** The real primary key values identifying the row to update should be 
+** stored in the corresponding columns of the data_% table row, as should
+** the new values of all columns being update. The text value in the 
+** "rbu_control" column must contain the same number of characters as
+** there are columns in the target database table, and must consist entirely
+** of 'x' and '.' characters (or in some special cases 'd' - see below). For 
+** each column that is being updated, the corresponding character is set to
+** 'x'. For those that remain as they are, the corresponding character of the
+** rbu_control value should be set to '.'. For example, given the tables 
+** above, the update statement:
+**
+**   UPDATE t1 SET c = 'usa' WHERE a = 4;
+**
+** is represented by the data_t1 row created by:
+**
+**   INSERT INTO data_t1(a, b, c, rbu_control) VALUES(4, NULL, 'usa', '..x');
+**
+** Instead of an 'x' character, characters of the rbu_control value specified
+** for UPDATEs may also be set to 'd'. In this case, instead of updating the
+** target table with the value stored in the corresponding data_% column, the
+** user-defined SQL function "rbu_delta()" is invoked and the result stored in
+** the target table column. rbu_delta() is invoked with two arguments - the
+** original value currently stored in the target table column and the 
+** value specified in the data_xxx table.
+**
+** For example, this row:
+**
+**   INSERT INTO data_t1(a, b, c, rbu_control) VALUES(4, NULL, 'usa', '..d');
+**
+** is similar to an UPDATE statement such as: 
+**
+**   UPDATE t1 SET c = rbu_delta(c, 'usa') WHERE a = 4;
+**
+** Finally, if an 'f' character appears in place of a 'd' or 's' in an 
+** ota_control string, the contents of the data_xxx table column is assumed
+** to be a "fossil delta" - a patch to be applied to a blob value in the
+** format used by the fossil source-code management system. In this case
+** the existing value within the target database table must be of type BLOB. 
+** It is replaced by the result of applying the specified fossil delta to
+** itself.
+**
+** If the target database table is a virtual table or a table with no PRIMARY
+** KEY, the rbu_control value should not include a character corresponding 
+** to the rbu_rowid value. For example, this:
+**
+**   INSERT INTO data_ft1(a, b, rbu_rowid, rbu_control) 
+**       VALUES(NULL, 'usa', 12, '.x');
+**
+** causes a result similar to:
+**
+**   UPDATE ft1 SET b = 'usa' WHERE rowid = 12;
+**
+** The data_xxx tables themselves should have no PRIMARY KEY declarations.
+** However, RBU is more efficient if reading the rows in from each data_xxx
+** table in "rowid" order is roughly the same as reading them sorted by
+** the PRIMARY KEY of the corresponding target database table. In other 
+** words, rows should be sorted using the destination table PRIMARY KEY 
+** fields before they are inserted into the data_xxx tables.
+**
+** USAGE
+**
+** The API declared below allows an application to apply an RBU update 
+** stored on disk to an existing target database. Essentially, the 
+** application:
+**
+**     1) Opens an RBU handle using the sqlite3rbu_open() function.
+**
+**     2) Registers any required virtual table modules with the database
+**        handle returned by sqlite3rbu_db(). Also, if required, register
+**        the rbu_delta() implementation.
+**
+**     3) Calls the sqlite3rbu_step() function one or more times on
+**        the new handle. Each call to sqlite3rbu_step() performs a single
+**        b-tree operation, so thousands of calls may be required to apply 
+**        a complete update.
+**
+**     4) Calls sqlite3rbu_close() to close the RBU update handle. If
+**        sqlite3rbu_step() has been called enough times to completely
+**        apply the update to the target database, then the RBU database
+**        is marked as fully applied. Otherwise, the state of the RBU 
+**        update application is saved in the RBU database for later 
+**        resumption.
+**
+** See comments below for more detail on APIs.
+**
+** If an update is only partially applied to the target database by the
+** time sqlite3rbu_close() is called, various state information is saved 
+** within the RBU database. This allows subsequent processes to automatically
+** resume the RBU update from where it left off.
+**
+** To remove all RBU extension state information, returning an RBU database 
+** to its original contents, it is sufficient to drop all tables that begin
+** with the prefix "rbu_"
+**
+** DATABASE LOCKING
+**
+** An RBU update may not be applied to a database in WAL mode. Attempting
+** to do so is an error (SQLITE_ERROR).
+**
+** While an RBU handle is open, a SHARED lock may be held on the target
+** database file. This means it is possible for other clients to read the
+** database, but not to write it.
+**
+** If an RBU update is started and then suspended before it is completed,
+** then an external client writes to the database, then attempting to resume
+** the suspended RBU update is also an error (SQLITE_BUSY).
+*/
+
+#ifndef _SQLITE3RBU_H
+#define _SQLITE3RBU_H
+
+/* #include "sqlite3.h"              ** Required for error code definitions ** */
+
+#if 0
+extern "C" {
+#endif
+
+typedef struct sqlite3rbu sqlite3rbu;
+
+/*
+** Open an RBU handle.
+**
+** Argument zTarget is the path to the target database. Argument zRbu is
+** the path to the RBU database. Each call to this function must be matched
+** by a call to sqlite3rbu_close(). When opening the databases, RBU passes
+** the SQLITE_CONFIG_URI flag to sqlite3_open_v2(). So if either zTarget
+** or zRbu begin with "file:", it will be interpreted as an SQLite 
+** database URI, not a regular file name.
+**
+** If the zState argument is passed a NULL value, the RBU extension stores 
+** the current state of the update (how many rows have been updated, which 
+** indexes are yet to be updated etc.) within the RBU database itself. This
+** can be convenient, as it means that the RBU application does not need to
+** organize removing a separate state file after the update is concluded. 
+** Or, if zState is non-NULL, it must be a path to a database file in which 
+** the RBU extension can store the state of the update.
+**
+** When resuming an RBU update, the zState argument must be passed the same
+** value as when the RBU update was started.
+**
+** Once the RBU update is finished, the RBU extension does not 
+** automatically remove any zState database file, even if it created it.
+**
+** By default, RBU uses the default VFS to access the files on disk. To
+** use a VFS other than the default, an SQLite "file:" URI containing a
+** "vfs=..." option may be passed as the zTarget option.
+**
+** IMPORTANT NOTE FOR ZIPVFS USERS: The RBU extension works with all of
+** SQLite's built-in VFSs, including the multiplexor VFS. However it does
+** not work out of the box with zipvfs. Refer to the comment describing
+** the zipvfs_create_vfs() API below for details on using RBU with zipvfs.
+*/
+SQLITE_API sqlite3rbu *sqlite3rbu_open(
+  const char *zTarget, 
+  const char *zRbu,
+  const char *zState
+);
+
+/*
+** Open an RBU handle to perform an RBU vacuum on database file zTarget.
+** An RBU vacuum is similar to SQLite's built-in VACUUM command, except
+** that it can be suspended and resumed like an RBU update.
+**
+** The second argument to this function identifies a database in which 
+** to store the state of the RBU vacuum operation if it is suspended. The 
+** first time sqlite3rbu_vacuum() is called, to start an RBU vacuum
+** operation, the state database should either not exist or be empty
+** (contain no tables). If an RBU vacuum is suspended by calling 
+** sqlite3rbu_close() on the RBU handle before sqlite3rbu_step() has
+** returned SQLITE_DONE, the vacuum state is stored in the state database. 
+** The vacuum can be resumed by calling this function to open a new RBU
+** handle specifying the same target and state databases.
+**
+** If the second argument passed to this function is NULL, then the
+** name of the state database is "<database>-vacuum", where <database>
+** is the name of the target database file. In this case, on UNIX, if the
+** state database is not already present in the file-system, it is created
+** with the same permissions as the target db is made.
+**
+** This function does not delete the state database after an RBU vacuum
+** is completed, even if it created it. However, if the call to
+** sqlite3rbu_close() returns any value other than SQLITE_OK, the contents
+** of the state tables within the state database are zeroed. This way,
+** the next call to sqlite3rbu_vacuum() opens a handle that starts a 
+** new RBU vacuum operation.
+**
+** As with sqlite3rbu_open(), Zipvfs users should rever to the comment
+** describing the sqlite3rbu_create_vfs() API function below for 
+** a description of the complications associated with using RBU with 
+** zipvfs databases.
+*/
+SQLITE_API sqlite3rbu *sqlite3rbu_vacuum(
+  const char *zTarget, 
+  const char *zState
+);
+
+/*
+** Internally, each RBU connection uses a separate SQLite database 
+** connection to access the target and rbu update databases. This
+** API allows the application direct access to these database handles.
+**
+** The first argument passed to this function must be a valid, open, RBU
+** handle. The second argument should be passed zero to access the target
+** database handle, or non-zero to access the rbu update database handle.
+** Accessing the underlying database handles may be useful in the
+** following scenarios:
+**
+**   * If any target tables are virtual tables, it may be necessary to
+**     call sqlite3_create_module() on the target database handle to 
+**     register the required virtual table implementations.
+**
+**   * If the data_xxx tables in the RBU source database are virtual 
+**     tables, the application may need to call sqlite3_create_module() on
+**     the rbu update db handle to any required virtual table
+**     implementations.
+**
+**   * If the application uses the "rbu_delta()" feature described above,
+**     it must use sqlite3_create_function() or similar to register the
+**     rbu_delta() implementation with the target database handle.
+**
+** If an error has occurred, either while opening or stepping the RBU object,
+** this function may return NULL. The error code and message may be collected
+** when sqlite3rbu_close() is called.
+**
+** Database handles returned by this function remain valid until the next
+** call to any sqlite3rbu_xxx() function other than sqlite3rbu_db().
+*/
+SQLITE_API sqlite3 *sqlite3rbu_db(sqlite3rbu*, int bRbu);
+
+/*
+** Do some work towards applying the RBU update to the target db. 
+**
+** Return SQLITE_DONE if the update has been completely applied, or 
+** SQLITE_OK if no error occurs but there remains work to do to apply
+** the RBU update. If an error does occur, some other error code is 
+** returned. 
+**
+** Once a call to sqlite3rbu_step() has returned a value other than
+** SQLITE_OK, all subsequent calls on the same RBU handle are no-ops
+** that immediately return the same value.
+*/
+SQLITE_API int sqlite3rbu_step(sqlite3rbu *pRbu);
+
+/*
+** Force RBU to save its state to disk.
+**
+** If a power failure or application crash occurs during an update, following
+** system recovery RBU may resume the update from the point at which the state
+** was last saved. In other words, from the most recent successful call to 
+** sqlite3rbu_close() or this function.
+**
+** SQLITE_OK is returned if successful, or an SQLite error code otherwise.
+*/
+SQLITE_API int sqlite3rbu_savestate(sqlite3rbu *pRbu);
+
+/*
+** Close an RBU handle. 
+**
+** If the RBU update has been completely applied, mark the RBU database
+** as fully applied. Otherwise, assuming no error has occurred, save the
+** current state of the RBU update appliation to the RBU database.
+**
+** If an error has already occurred as part of an sqlite3rbu_step()
+** or sqlite3rbu_open() call, or if one occurs within this function, an
+** SQLite error code is returned. Additionally, *pzErrmsg may be set to
+** point to a buffer containing a utf-8 formatted English language error
+** message. It is the responsibility of the caller to eventually free any 
+** such buffer using sqlite3_free().
+**
+** Otherwise, if no error occurs, this function returns SQLITE_OK if the
+** update has been partially applied, or SQLITE_DONE if it has been 
+** completely applied.
+*/
+SQLITE_API int sqlite3rbu_close(sqlite3rbu *pRbu, char **pzErrmsg);
+
+/*
+** Return the total number of key-value operations (inserts, deletes or 
+** updates) that have been performed on the target database since the
+** current RBU update was started.
+*/
+SQLITE_API sqlite3_int64 sqlite3rbu_progress(sqlite3rbu *pRbu);
+
+/*
+** Obtain permyriadage (permyriadage is to 10000 as percentage is to 100) 
+** progress indications for the two stages of an RBU update. This API may
+** be useful for driving GUI progress indicators and similar.
+**
+** An RBU update is divided into two stages:
+**
+**   * Stage 1, in which changes are accumulated in an oal/wal file, and
+**   * Stage 2, in which the contents of the wal file are copied into the
+**     main database.
+**
+** The update is visible to non-RBU clients during stage 2. During stage 1
+** non-RBU reader clients may see the original database.
+**
+** If this API is called during stage 2 of the update, output variable 
+** (*pnOne) is set to 10000 to indicate that stage 1 has finished and (*pnTwo)
+** to a value between 0 and 10000 to indicate the permyriadage progress of
+** stage 2. A value of 5000 indicates that stage 2 is half finished, 
+** 9000 indicates that it is 90% finished, and so on.
+**
+** If this API is called during stage 1 of the update, output variable 
+** (*pnTwo) is set to 0 to indicate that stage 2 has not yet started. The
+** value to which (*pnOne) is set depends on whether or not the RBU 
+** database contains an "rbu_count" table. The rbu_count table, if it 
+** exists, must contain the same columns as the following:
+**
+**   CREATE TABLE rbu_count(tbl TEXT PRIMARY KEY, cnt INTEGER) WITHOUT ROWID;
+**
+** There must be one row in the table for each source (data_xxx) table within
+** the RBU database. The 'tbl' column should contain the name of the source
+** table. The 'cnt' column should contain the number of rows within the
+** source table.
+**
+** If the rbu_count table is present and populated correctly and this
+** API is called during stage 1, the *pnOne output variable is set to the
+** permyriadage progress of the same stage. If the rbu_count table does
+** not exist, then (*pnOne) is set to -1 during stage 1. If the rbu_count
+** table exists but is not correctly populated, the value of the *pnOne
+** output variable during stage 1 is undefined.
+*/
+SQLITE_API void sqlite3rbu_bp_progress(sqlite3rbu *pRbu, int *pnOne, int *pnTwo);
+
+/*
+** Obtain an indication as to the current stage of an RBU update or vacuum.
+** This function always returns one of the SQLITE_RBU_STATE_XXX constants
+** defined in this file. Return values should be interpreted as follows:
+**
+** SQLITE_RBU_STATE_OAL:
+**   RBU is currently building a *-oal file. The next call to sqlite3rbu_step()
+**   may either add further data to the *-oal file, or compute data that will
+**   be added by a subsequent call.
+**
+** SQLITE_RBU_STATE_MOVE:
+**   RBU has finished building the *-oal file. The next call to sqlite3rbu_step()
+**   will move the *-oal file to the equivalent *-wal path. If the current
+**   operation is an RBU update, then the updated version of the database
+**   file will become visible to ordinary SQLite clients following the next
+**   call to sqlite3rbu_step().
+**
+** SQLITE_RBU_STATE_CHECKPOINT:
+**   RBU is currently performing an incremental checkpoint. The next call to
+**   sqlite3rbu_step() will copy a page of data from the *-wal file into
+**   the target database file.
+**
+** SQLITE_RBU_STATE_DONE:
+**   The RBU operation has finished. Any subsequent calls to sqlite3rbu_step()
+**   will immediately return SQLITE_DONE.
+**
+** SQLITE_RBU_STATE_ERROR:
+**   An error has occurred. Any subsequent calls to sqlite3rbu_step() will
+**   immediately return the SQLite error code associated with the error.
+*/
+#define SQLITE_RBU_STATE_OAL        1
+#define SQLITE_RBU_STATE_MOVE       2
+#define SQLITE_RBU_STATE_CHECKPOINT 3
+#define SQLITE_RBU_STATE_DONE       4
+#define SQLITE_RBU_STATE_ERROR      5
+
+SQLITE_API int sqlite3rbu_state(sqlite3rbu *pRbu);
+
+/*
+** Create an RBU VFS named zName that accesses the underlying file-system
+** via existing VFS zParent. Or, if the zParent parameter is passed NULL, 
+** then the new RBU VFS uses the default system VFS to access the file-system.
+** The new object is registered as a non-default VFS with SQLite before 
+** returning.
+**
+** Part of the RBU implementation uses a custom VFS object. Usually, this
+** object is created and deleted automatically by RBU. 
+**
+** The exception is for applications that also use zipvfs. In this case,
+** the custom VFS must be explicitly created by the user before the RBU
+** handle is opened. The RBU VFS should be installed so that the zipvfs
+** VFS uses the RBU VFS, which in turn uses any other VFS layers in use 
+** (for example multiplexor) to access the file-system. For example,
+** to assemble an RBU enabled VFS stack that uses both zipvfs and 
+** multiplexor (error checking omitted):
+**
+**     // Create a VFS named "multiplex" (not the default).
+**     sqlite3_multiplex_initialize(0, 0);
+**
+**     // Create an rbu VFS named "rbu" that uses multiplexor. If the
+**     // second argument were replaced with NULL, the "rbu" VFS would
+**     // access the file-system via the system default VFS, bypassing the
+**     // multiplexor.
+**     sqlite3rbu_create_vfs("rbu", "multiplex");
+**
+**     // Create a zipvfs VFS named "zipvfs" that uses rbu.
+**     zipvfs_create_vfs_v3("zipvfs", "rbu", 0, xCompressorAlgorithmDetector);
+**
+**     // Make zipvfs the default VFS.
+**     sqlite3_vfs_register(sqlite3_vfs_find("zipvfs"), 1);
+**
+** Because the default VFS created above includes a RBU functionality, it
+** may be used by RBU clients. Attempting to use RBU with a zipvfs VFS stack
+** that does not include the RBU layer results in an error.
+**
+** The overhead of adding the "rbu" VFS to the system is negligible for 
+** non-RBU users. There is no harm in an application accessing the 
+** file-system via "rbu" all the time, even if it only uses RBU functionality 
+** occasionally.
+*/
+SQLITE_API int sqlite3rbu_create_vfs(const char *zName, const char *zParent);
+
+/*
+** Deregister and destroy an RBU vfs created by an earlier call to
+** sqlite3rbu_create_vfs().
+**
+** VFS objects are not reference counted. If a VFS object is destroyed
+** before all database handles that use it have been closed, the results
+** are undefined.
+*/
+SQLITE_API void sqlite3rbu_destroy_vfs(const char *zName);
+
+#if 0
+}  /* end of the 'extern "C"' block */
+#endif
+
+#endif /* _SQLITE3RBU_H */
+
+/************** End of sqlite3rbu.h ******************************************/
+/************** Continuing where we left off in sqlite3rbu.c *****************/
+
+#if defined(_WIN32_WCE)
+/* #include "windows.h" */
+#endif
+
+/* Maximum number of prepared UPDATE statements held by this module */
+#define SQLITE_RBU_UPDATE_CACHESIZE 16
+
+/*
+** Swap two objects of type TYPE.
+*/
+#if !defined(SQLITE_AMALGAMATION)
+# define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}
+#endif
+
+/*
+** The rbu_state table is used to save the state of a partially applied
+** update so that it can be resumed later. The table consists of integer
+** keys mapped to values as follows:
+**
+** RBU_STATE_STAGE:
+**   May be set to integer values 1, 2, 4 or 5. As follows:
+**       1: the *-rbu file is currently under construction.
+**       2: the *-rbu file has been constructed, but not yet moved 
+**          to the *-wal path.
+**       4: the checkpoint is underway.
+**       5: the rbu update has been checkpointed.
+**
+** RBU_STATE_TBL:
+**   Only valid if STAGE==1. The target database name of the table 
+**   currently being written.
+**
+** RBU_STATE_IDX:
+**   Only valid if STAGE==1. The target database name of the index 
+**   currently being written, or NULL if the main table is currently being
+**   updated.
+**
+** RBU_STATE_ROW:
+**   Only valid if STAGE==1. Number of rows already processed for the current
+**   table/index.
+**
+** RBU_STATE_PROGRESS:
+**   Trbul number of sqlite3rbu_step() calls made so far as part of this
+**   rbu update.
+**
+** RBU_STATE_CKPT:
+**   Valid if STAGE==4. The 64-bit checksum associated with the wal-index
+**   header created by recovering the *-wal file. This is used to detect
+**   cases when another client appends frames to the *-wal file in the
+**   middle of an incremental checkpoint (an incremental checkpoint cannot
+**   be continued if this happens).
+**
+** RBU_STATE_COOKIE:
+**   Valid if STAGE==1. The current change-counter cookie value in the 
+**   target db file.
+**
+** RBU_STATE_OALSZ:
+**   Valid if STAGE==1. The size in bytes of the *-oal file.
+*/
+#define RBU_STATE_STAGE        1
+#define RBU_STATE_TBL          2
+#define RBU_STATE_IDX          3
+#define RBU_STATE_ROW          4
+#define RBU_STATE_PROGRESS     5
+#define RBU_STATE_CKPT         6
+#define RBU_STATE_COOKIE       7
+#define RBU_STATE_OALSZ        8
+#define RBU_STATE_PHASEONESTEP 9
+
+#define RBU_STAGE_OAL         1
+#define RBU_STAGE_MOVE        2
+#define RBU_STAGE_CAPTURE     3
+#define RBU_STAGE_CKPT        4
+#define RBU_STAGE_DONE        5
+
+
+#define RBU_CREATE_STATE \
+  "CREATE TABLE IF NOT EXISTS %s.rbu_state(k INTEGER PRIMARY KEY, v)"
+
+typedef struct RbuFrame RbuFrame;
+typedef struct RbuObjIter RbuObjIter;
+typedef struct RbuState RbuState;
+typedef struct rbu_vfs rbu_vfs;
+typedef struct rbu_file rbu_file;
+typedef struct RbuUpdateStmt RbuUpdateStmt;
+
+#if !defined(SQLITE_AMALGAMATION)
+typedef unsigned int u32;
+typedef unsigned short u16;
+typedef unsigned char u8;
+typedef sqlite3_int64 i64;
+#endif
+
+/*
+** These values must match the values defined in wal.c for the equivalent
+** locks. These are not magic numbers as they are part of the SQLite file
+** format.
+*/
+#define WAL_LOCK_WRITE  0
+#define WAL_LOCK_CKPT   1
+#define WAL_LOCK_READ0  3
+
+#define SQLITE_FCNTL_RBUCNT    5149216
+
+/*
+** A structure to store values read from the rbu_state table in memory.
+*/
+struct RbuState {
+  int eStage;
+  char *zTbl;
+  char *zIdx;
+  i64 iWalCksum;
+  int nRow;
+  i64 nProgress;
+  u32 iCookie;
+  i64 iOalSz;
+  i64 nPhaseOneStep;
+};
+
+struct RbuUpdateStmt {
+  char *zMask;                    /* Copy of update mask used with pUpdate */
+  sqlite3_stmt *pUpdate;          /* Last update statement (or NULL) */
+  RbuUpdateStmt *pNext;
+};
+
+/*
+** An iterator of this type is used to iterate through all objects in
+** the target database that require updating. For each such table, the
+** iterator visits, in order:
+**
+**     * the table itself, 
+**     * each index of the table (zero or more points to visit), and
+**     * a special "cleanup table" state.
+**
+** abIndexed:
+**   If the table has no indexes on it, abIndexed is set to NULL. Otherwise,
+**   it points to an array of flags nTblCol elements in size. The flag is
+**   set for each column that is either a part of the PK or a part of an
+**   index. Or clear otherwise.
+**   
+*/
+struct RbuObjIter {
+  sqlite3_stmt *pTblIter;         /* Iterate through tables */
+  sqlite3_stmt *pIdxIter;         /* Index iterator */
+  int nTblCol;                    /* Size of azTblCol[] array */
+  char **azTblCol;                /* Array of unquoted target column names */
+  char **azTblType;               /* Array of target column types */
+  int *aiSrcOrder;                /* src table col -> target table col */
+  u8 *abTblPk;                    /* Array of flags, set on target PK columns */
+  u8 *abNotNull;                  /* Array of flags, set on NOT NULL columns */
+  u8 *abIndexed;                  /* Array of flags, set on indexed & PK cols */
+  int eType;                      /* Table type - an RBU_PK_XXX value */
+
+  /* Output variables. zTbl==0 implies EOF. */
+  int bCleanup;                   /* True in "cleanup" state */
+  const char *zTbl;               /* Name of target db table */
+  const char *zDataTbl;           /* Name of rbu db table (or null) */
+  const char *zIdx;               /* Name of target db index (or null) */
+  int iTnum;                      /* Root page of current object */
+  int iPkTnum;                    /* If eType==EXTERNAL, root of PK index */
+  int bUnique;                    /* Current index is unique */
+  int nIndex;                     /* Number of aux. indexes on table zTbl */
+
+  /* Statements created by rbuObjIterPrepareAll() */
+  int nCol;                       /* Number of columns in current object */
+  sqlite3_stmt *pSelect;          /* Source data */
+  sqlite3_stmt *pInsert;          /* Statement for INSERT operations */
+  sqlite3_stmt *pDelete;          /* Statement for DELETE ops */
+  sqlite3_stmt *pTmpInsert;       /* Insert into rbu_tmp_$zDataTbl */
+
+  /* Last UPDATE used (for PK b-tree updates only), or NULL. */
+  RbuUpdateStmt *pRbuUpdate;
+};
+
+/*
+** Values for RbuObjIter.eType
+**
+**     0: Table does not exist (error)
+**     1: Table has an implicit rowid.
+**     2: Table has an explicit IPK column.
+**     3: Table has an external PK index.
+**     4: Table is WITHOUT ROWID.
+**     5: Table is a virtual table.
+*/
+#define RBU_PK_NOTABLE        0
+#define RBU_PK_NONE           1
+#define RBU_PK_IPK            2
+#define RBU_PK_EXTERNAL       3
+#define RBU_PK_WITHOUT_ROWID  4
+#define RBU_PK_VTAB           5
+
+
+/*
+** Within the RBU_STAGE_OAL stage, each call to sqlite3rbu_step() performs
+** one of the following operations.
+*/
+#define RBU_INSERT     1          /* Insert on a main table b-tree */
+#define RBU_DELETE     2          /* Delete a row from a main table b-tree */
+#define RBU_REPLACE    3          /* Delete and then insert a row */
+#define RBU_IDX_DELETE 4          /* Delete a row from an aux. index b-tree */
+#define RBU_IDX_INSERT 5          /* Insert on an aux. index b-tree */
+
+#define RBU_UPDATE     6          /* Update a row in a main table b-tree */
+
+/*
+** A single step of an incremental checkpoint - frame iWalFrame of the wal
+** file should be copied to page iDbPage of the database file.
+*/
+struct RbuFrame {
+  u32 iDbPage;
+  u32 iWalFrame;
+};
+
+/*
+** RBU handle.
+**
+** nPhaseOneStep:
+**   If the RBU database contains an rbu_count table, this value is set to
+**   a running estimate of the number of b-tree operations required to 
+**   finish populating the *-oal file. This allows the sqlite3_bp_progress()
+**   API to calculate the permyriadage progress of populating the *-oal file
+**   using the formula:
+**
+**     permyriadage = (10000 * nProgress) / nPhaseOneStep
+**
+**   nPhaseOneStep is initialized to the sum of:
+**
+**     nRow * (nIndex + 1)
+**
+**   for all source tables in the RBU database, where nRow is the number
+**   of rows in the source table and nIndex the number of indexes on the
+**   corresponding target database table.
+**
+**   This estimate is accurate if the RBU update consists entirely of
+**   INSERT operations. However, it is inaccurate if:
+**
+**     * the RBU update contains any UPDATE operations. If the PK specified
+**       for an UPDATE operation does not exist in the target table, then
+**       no b-tree operations are required on index b-trees. Or if the 
+**       specified PK does exist, then (nIndex*2) such operations are
+**       required (one delete and one insert on each index b-tree).
+**
+**     * the RBU update contains any DELETE operations for which the specified
+**       PK does not exist. In this case no operations are required on index
+**       b-trees.
+**
+**     * the RBU update contains REPLACE operations. These are similar to
+**       UPDATE operations.
+**
+**   nPhaseOneStep is updated to account for the conditions above during the
+**   first pass of each source table. The updated nPhaseOneStep value is
+**   stored in the rbu_state table if the RBU update is suspended.
+*/
+struct sqlite3rbu {
+  int eStage;                     /* Value of RBU_STATE_STAGE field */
+  sqlite3 *dbMain;                /* target database handle */
+  sqlite3 *dbRbu;                 /* rbu database handle */
+  char *zTarget;                  /* Path to target db */
+  char *zRbu;                     /* Path to rbu db */
+  char *zState;                   /* Path to state db (or NULL if zRbu) */
+  char zStateDb[5];               /* Db name for state ("stat" or "main") */
+  int rc;                         /* Value returned by last rbu_step() call */
+  char *zErrmsg;                  /* Error message if rc!=SQLITE_OK */
+  int nStep;                      /* Rows processed for current object */
+  int nProgress;                  /* Rows processed for all objects */
+  RbuObjIter objiter;             /* Iterator for skipping through tbl/idx */
+  const char *zVfsName;           /* Name of automatically created rbu vfs */
+  rbu_file *pTargetFd;            /* File handle open on target db */
+  i64 iOalSz;
+  i64 nPhaseOneStep;
+
+  /* The following state variables are used as part of the incremental
+  ** checkpoint stage (eStage==RBU_STAGE_CKPT). See comments surrounding
+  ** function rbuSetupCheckpoint() for details.  */
+  u32 iMaxFrame;                  /* Largest iWalFrame value in aFrame[] */
+  u32 mLock;
+  int nFrame;                     /* Entries in aFrame[] array */
+  int nFrameAlloc;                /* Allocated size of aFrame[] array */
+  RbuFrame *aFrame;
+  int pgsz;
+  u8 *aBuf;
+  i64 iWalCksum;
+
+  /* Used in RBU vacuum mode only */
+  int nRbu;                       /* Number of RBU VFS in the stack */
+  rbu_file *pRbuFd;               /* Fd for main db of dbRbu */
+};
+
+/*
+** An rbu VFS is implemented using an instance of this structure.
+*/
+struct rbu_vfs {
+  sqlite3_vfs base;               /* rbu VFS shim methods */
+  sqlite3_vfs *pRealVfs;          /* Underlying VFS */
+  sqlite3_mutex *mutex;           /* Mutex to protect pMain */
+  rbu_file *pMain;                /* Linked list of main db files */
+};
+
+/*
+** Each file opened by an rbu VFS is represented by an instance of
+** the following structure.
+*/
+struct rbu_file {
+  sqlite3_file base;              /* sqlite3_file methods */
+  sqlite3_file *pReal;            /* Underlying file handle */
+  rbu_vfs *pRbuVfs;               /* Pointer to the rbu_vfs object */
+  sqlite3rbu *pRbu;               /* Pointer to rbu object (rbu target only) */
+
+  int openFlags;                  /* Flags this file was opened with */
+  u32 iCookie;                    /* Cookie value for main db files */
+  u8 iWriteVer;                   /* "write-version" value for main db files */
+  u8 bNolock;                     /* True to fail EXCLUSIVE locks */
+
+  int nShm;                       /* Number of entries in apShm[] array */
+  char **apShm;                   /* Array of mmap'd *-shm regions */
+  char *zDel;                     /* Delete this when closing file */
+
+  const char *zWal;               /* Wal filename for this main db file */
+  rbu_file *pWalFd;               /* Wal file descriptor for this main db */
+  rbu_file *pMainNext;            /* Next MAIN_DB file */
+};
+
+/*
+** True for an RBU vacuum handle, or false otherwise.
+*/
+#define rbuIsVacuum(p) ((p)->zTarget==0)
+
+
+/*************************************************************************
+** The following three functions, found below:
+**
+**   rbuDeltaGetInt()
+**   rbuDeltaChecksum()
+**   rbuDeltaApply()
+**
+** are lifted from the fossil source code (http://fossil-scm.org). They
+** are used to implement the scalar SQL function rbu_fossil_delta().
+*/
+
+/*
+** Read bytes from *pz and convert them into a positive integer.  When
+** finished, leave *pz pointing to the first character past the end of
+** the integer.  The *pLen parameter holds the length of the string
+** in *pz and is decremented once for each character in the integer.
+*/
+static unsigned int rbuDeltaGetInt(const char **pz, int *pLen){
+  static const signed char zValue[] = {
+    -1, -1, -1, -1, -1, -1, -1, -1,   -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1,   -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1,   -1, -1, -1, -1, -1, -1, -1, -1,
+     0,  1,  2,  3,  4,  5,  6,  7,    8,  9, -1, -1, -1, -1, -1, -1,
+    -1, 10, 11, 12, 13, 14, 15, 16,   17, 18, 19, 20, 21, 22, 23, 24,
+    25, 26, 27, 28, 29, 30, 31, 32,   33, 34, 35, -1, -1, -1, -1, 36,
+    -1, 37, 38, 39, 40, 41, 42, 43,   44, 45, 46, 47, 48, 49, 50, 51,
+    52, 53, 54, 55, 56, 57, 58, 59,   60, 61, 62, -1, -1, -1, 63, -1,
+  };
+  unsigned int v = 0;
+  int c;
+  unsigned char *z = (unsigned char*)*pz;
+  unsigned char *zStart = z;
+  while( (c = zValue[0x7f&*(z++)])>=0 ){
+     v = (v<<6) + c;
+  }
+  z--;
+  *pLen -= z - zStart;
+  *pz = (char*)z;
+  return v;
+}
+
+/*
+** Compute a 32-bit checksum on the N-byte buffer.  Return the result.
+*/
+static unsigned int rbuDeltaChecksum(const char *zIn, size_t N){
+  const unsigned char *z = (const unsigned char *)zIn;
+  unsigned sum0 = 0;
+  unsigned sum1 = 0;
+  unsigned sum2 = 0;
+  unsigned sum3 = 0;
+  while(N >= 16){
+    sum0 += ((unsigned)z[0] + z[4] + z[8] + z[12]);
+    sum1 += ((unsigned)z[1] + z[5] + z[9] + z[13]);
+    sum2 += ((unsigned)z[2] + z[6] + z[10]+ z[14]);
+    sum3 += ((unsigned)z[3] + z[7] + z[11]+ z[15]);
+    z += 16;
+    N -= 16;
+  }
+  while(N >= 4){
+    sum0 += z[0];
+    sum1 += z[1];
+    sum2 += z[2];
+    sum3 += z[3];
+    z += 4;
+    N -= 4;
+  }
+  sum3 += (sum2 << 8) + (sum1 << 16) + (sum0 << 24);
+  switch(N){
+    case 3:   sum3 += (z[2] << 8);
+    case 2:   sum3 += (z[1] << 16);
+    case 1:   sum3 += (z[0] << 24);
+    default:  ;
+  }
+  return sum3;
+}
+
+/*
+** Apply a delta.
+**
+** The output buffer should be big enough to hold the whole output
+** file and a NUL terminator at the end.  The delta_output_size()
+** routine will determine this size for you.
+**
+** The delta string should be null-terminated.  But the delta string
+** may contain embedded NUL characters (if the input and output are
+** binary files) so we also have to pass in the length of the delta in
+** the lenDelta parameter.
+**
+** This function returns the size of the output file in bytes (excluding
+** the final NUL terminator character).  Except, if the delta string is
+** malformed or intended for use with a source file other than zSrc,
+** then this routine returns -1.
+**
+** Refer to the delta_create() documentation above for a description
+** of the delta file format.
+*/
+static int rbuDeltaApply(
+  const char *zSrc,      /* The source or pattern file */
+  int lenSrc,            /* Length of the source file */
+  const char *zDelta,    /* Delta to apply to the pattern */
+  int lenDelta,          /* Length of the delta */
+  char *zOut             /* Write the output into this preallocated buffer */
+){
+  unsigned int limit;
+  unsigned int total = 0;
+#ifndef FOSSIL_OMIT_DELTA_CKSUM_TEST
+  char *zOrigOut = zOut;
+#endif
+
+  limit = rbuDeltaGetInt(&zDelta, &lenDelta);
+  if( *zDelta!='\n' ){
+    /* ERROR: size integer not terminated by "\n" */
+    return -1;
+  }
+  zDelta++; lenDelta--;
+  while( *zDelta && lenDelta>0 ){
+    unsigned int cnt, ofst;
+    cnt = rbuDeltaGetInt(&zDelta, &lenDelta);
+    switch( zDelta[0] ){
+      case '@': {
+        zDelta++; lenDelta--;
+        ofst = rbuDeltaGetInt(&zDelta, &lenDelta);
+        if( lenDelta>0 && zDelta[0]!=',' ){
+          /* ERROR: copy command not terminated by ',' */
+          return -1;
+        }
+        zDelta++; lenDelta--;
+        total += cnt;
+        if( total>limit ){
+          /* ERROR: copy exceeds output file size */
+          return -1;
+        }
+        if( (int)(ofst+cnt) > lenSrc ){
+          /* ERROR: copy extends past end of input */
+          return -1;
+        }
+        memcpy(zOut, &zSrc[ofst], cnt);
+        zOut += cnt;
+        break;
+      }
+      case ':': {
+        zDelta++; lenDelta--;
+        total += cnt;
+        if( total>limit ){
+          /* ERROR:  insert command gives an output larger than predicted */
+          return -1;
+        }
+        if( (int)cnt>lenDelta ){
+          /* ERROR: insert count exceeds size of delta */
+          return -1;
+        }
+        memcpy(zOut, zDelta, cnt);
+        zOut += cnt;
+        zDelta += cnt;
+        lenDelta -= cnt;
+        break;
+      }
+      case ';': {
+        zDelta++; lenDelta--;
+        zOut[0] = 0;
+#ifndef FOSSIL_OMIT_DELTA_CKSUM_TEST
+        if( cnt!=rbuDeltaChecksum(zOrigOut, total) ){
+          /* ERROR:  bad checksum */
+          return -1;
+        }
+#endif
+        if( total!=limit ){
+          /* ERROR: generated size does not match predicted size */
+          return -1;
+        }
+        return total;
+      }
+      default: {
+        /* ERROR: unknown delta operator */
+        return -1;
+      }
+    }
+  }
+  /* ERROR: unterminated delta */
+  return -1;
+}
+
+static int rbuDeltaOutputSize(const char *zDelta, int lenDelta){
+  int size;
+  size = rbuDeltaGetInt(&zDelta, &lenDelta);
+  if( *zDelta!='\n' ){
+    /* ERROR: size integer not terminated by "\n" */
+    return -1;
+  }
+  return size;
+}
+
+/*
+** End of code taken from fossil.
+*************************************************************************/
+
+/*
+** Implementation of SQL scalar function rbu_fossil_delta().
+**
+** This function applies a fossil delta patch to a blob. Exactly two
+** arguments must be passed to this function. The first is the blob to
+** patch and the second the patch to apply. If no error occurs, this
+** function returns the patched blob.
+*/
+static void rbuFossilDeltaFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  const char *aDelta;
+  int nDelta;
+  const char *aOrig;
+  int nOrig;
+
+  int nOut;
+  int nOut2;
+  char *aOut;
+
+  assert( argc==2 );
+
+  nOrig = sqlite3_value_bytes(argv[0]);
+  aOrig = (const char*)sqlite3_value_blob(argv[0]);
+  nDelta = sqlite3_value_bytes(argv[1]);
+  aDelta = (const char*)sqlite3_value_blob(argv[1]);
+
+  /* Figure out the size of the output */
+  nOut = rbuDeltaOutputSize(aDelta, nDelta);
+  if( nOut<0 ){
+    sqlite3_result_error(context, "corrupt fossil delta", -1);
+    return;
+  }
+
+  aOut = sqlite3_malloc(nOut+1);
+  if( aOut==0 ){
+    sqlite3_result_error_nomem(context);
+  }else{
+    nOut2 = rbuDeltaApply(aOrig, nOrig, aDelta, nDelta, aOut);
+    if( nOut2!=nOut ){
+      sqlite3_result_error(context, "corrupt fossil delta", -1);
+    }else{
+      sqlite3_result_blob(context, aOut, nOut, sqlite3_free);
+    }
+  }
+}
+
+
+/*
+** Prepare the SQL statement in buffer zSql against database handle db.
+** If successful, set *ppStmt to point to the new statement and return
+** SQLITE_OK. 
+**
+** Otherwise, if an error does occur, set *ppStmt to NULL and return
+** an SQLite error code. Additionally, set output variable *pzErrmsg to
+** point to a buffer containing an error message. It is the responsibility
+** of the caller to (eventually) free this buffer using sqlite3_free().
+*/
+static int prepareAndCollectError(
+  sqlite3 *db, 
+  sqlite3_stmt **ppStmt,
+  char **pzErrmsg,
+  const char *zSql
+){
+  int rc = sqlite3_prepare_v2(db, zSql, -1, ppStmt, 0);
+  if( rc!=SQLITE_OK ){
+    *pzErrmsg = sqlite3_mprintf("%s", sqlite3_errmsg(db));
+    *ppStmt = 0;
+  }
+  return rc;
+}
+
+/*
+** Reset the SQL statement passed as the first argument. Return a copy
+** of the value returned by sqlite3_reset().
+**
+** If an error has occurred, then set *pzErrmsg to point to a buffer
+** containing an error message. It is the responsibility of the caller
+** to eventually free this buffer using sqlite3_free().
+*/
+static int resetAndCollectError(sqlite3_stmt *pStmt, char **pzErrmsg){
+  int rc = sqlite3_reset(pStmt);
+  if( rc!=SQLITE_OK ){
+    *pzErrmsg = sqlite3_mprintf("%s", sqlite3_errmsg(sqlite3_db_handle(pStmt)));
+  }
+  return rc;
+}
+
+/*
+** Unless it is NULL, argument zSql points to a buffer allocated using
+** sqlite3_malloc containing an SQL statement. This function prepares the SQL
+** statement against database db and frees the buffer. If statement 
+** compilation is successful, *ppStmt is set to point to the new statement 
+** handle and SQLITE_OK is returned. 
+**
+** Otherwise, if an error occurs, *ppStmt is set to NULL and an error code
+** returned. In this case, *pzErrmsg may also be set to point to an error
+** message. It is the responsibility of the caller to free this error message
+** buffer using sqlite3_free().
+**
+** If argument zSql is NULL, this function assumes that an OOM has occurred.
+** In this case SQLITE_NOMEM is returned and *ppStmt set to NULL.
+*/
+static int prepareFreeAndCollectError(
+  sqlite3 *db, 
+  sqlite3_stmt **ppStmt,
+  char **pzErrmsg,
+  char *zSql
+){
+  int rc;
+  assert( *pzErrmsg==0 );
+  if( zSql==0 ){
+    rc = SQLITE_NOMEM;
+    *ppStmt = 0;
+  }else{
+    rc = prepareAndCollectError(db, ppStmt, pzErrmsg, zSql);
+    sqlite3_free(zSql);
+  }
+  return rc;
+}
+
+/*
+** Free the RbuObjIter.azTblCol[] and RbuObjIter.abTblPk[] arrays allocated
+** by an earlier call to rbuObjIterCacheTableInfo().
+*/
+static void rbuObjIterFreeCols(RbuObjIter *pIter){
+  int i;
+  for(i=0; i<pIter->nTblCol; i++){
+    sqlite3_free(pIter->azTblCol[i]);
+    sqlite3_free(pIter->azTblType[i]);
+  }
+  sqlite3_free(pIter->azTblCol);
+  pIter->azTblCol = 0;
+  pIter->azTblType = 0;
+  pIter->aiSrcOrder = 0;
+  pIter->abTblPk = 0;
+  pIter->abNotNull = 0;
+  pIter->nTblCol = 0;
+  pIter->eType = 0;               /* Invalid value */
+}
+
+/*
+** Finalize all statements and free all allocations that are specific to
+** the current object (table/index pair).
+*/
+static void rbuObjIterClearStatements(RbuObjIter *pIter){
+  RbuUpdateStmt *pUp;
+
+  sqlite3_finalize(pIter->pSelect);
+  sqlite3_finalize(pIter->pInsert);
+  sqlite3_finalize(pIter->pDelete);
+  sqlite3_finalize(pIter->pTmpInsert);
+  pUp = pIter->pRbuUpdate;
+  while( pUp ){
+    RbuUpdateStmt *pTmp = pUp->pNext;
+    sqlite3_finalize(pUp->pUpdate);
+    sqlite3_free(pUp);
+    pUp = pTmp;
+  }
+  
+  pIter->pSelect = 0;
+  pIter->pInsert = 0;
+  pIter->pDelete = 0;
+  pIter->pRbuUpdate = 0;
+  pIter->pTmpInsert = 0;
+  pIter->nCol = 0;
+}
+
+/*
+** Clean up any resources allocated as part of the iterator object passed
+** as the only argument.
+*/
+static void rbuObjIterFinalize(RbuObjIter *pIter){
+  rbuObjIterClearStatements(pIter);
+  sqlite3_finalize(pIter->pTblIter);
+  sqlite3_finalize(pIter->pIdxIter);
+  rbuObjIterFreeCols(pIter);
+  memset(pIter, 0, sizeof(RbuObjIter));
+}
+
+/*
+** Advance the iterator to the next position.
+**
+** If no error occurs, SQLITE_OK is returned and the iterator is left 
+** pointing to the next entry. Otherwise, an error code and message is 
+** left in the RBU handle passed as the first argument. A copy of the 
+** error code is returned.
+*/
+static int rbuObjIterNext(sqlite3rbu *p, RbuObjIter *pIter){
+  int rc = p->rc;
+  if( rc==SQLITE_OK ){
+
+    /* Free any SQLite statements used while processing the previous object */ 
+    rbuObjIterClearStatements(pIter);
+    if( pIter->zIdx==0 ){
+      rc = sqlite3_exec(p->dbMain,
+          "DROP TRIGGER IF EXISTS temp.rbu_insert_tr;"
+          "DROP TRIGGER IF EXISTS temp.rbu_update1_tr;"
+          "DROP TRIGGER IF EXISTS temp.rbu_update2_tr;"
+          "DROP TRIGGER IF EXISTS temp.rbu_delete_tr;"
+          , 0, 0, &p->zErrmsg
+      );
+    }
+
+    if( rc==SQLITE_OK ){
+      if( pIter->bCleanup ){
+        rbuObjIterFreeCols(pIter);
+        pIter->bCleanup = 0;
+        rc = sqlite3_step(pIter->pTblIter);
+        if( rc!=SQLITE_ROW ){
+          rc = resetAndCollectError(pIter->pTblIter, &p->zErrmsg);
+          pIter->zTbl = 0;
+        }else{
+          pIter->zTbl = (const char*)sqlite3_column_text(pIter->pTblIter, 0);
+          pIter->zDataTbl = (const char*)sqlite3_column_text(pIter->pTblIter,1);
+          rc = (pIter->zDataTbl && pIter->zTbl) ? SQLITE_OK : SQLITE_NOMEM;
+        }
+      }else{
+        if( pIter->zIdx==0 ){
+          sqlite3_stmt *pIdx = pIter->pIdxIter;
+          rc = sqlite3_bind_text(pIdx, 1, pIter->zTbl, -1, SQLITE_STATIC);
+        }
+        if( rc==SQLITE_OK ){
+          rc = sqlite3_step(pIter->pIdxIter);
+          if( rc!=SQLITE_ROW ){
+            rc = resetAndCollectError(pIter->pIdxIter, &p->zErrmsg);
+            pIter->bCleanup = 1;
+            pIter->zIdx = 0;
+          }else{
+            pIter->zIdx = (const char*)sqlite3_column_text(pIter->pIdxIter, 0);
+            pIter->iTnum = sqlite3_column_int(pIter->pIdxIter, 1);
+            pIter->bUnique = sqlite3_column_int(pIter->pIdxIter, 2);
+            rc = pIter->zIdx ? SQLITE_OK : SQLITE_NOMEM;
+          }
+        }
+      }
+    }
+  }
+
+  if( rc!=SQLITE_OK ){
+    rbuObjIterFinalize(pIter);
+    p->rc = rc;
+  }
+  return rc;
+}
+
+
+/*
+** The implementation of the rbu_target_name() SQL function. This function
+** accepts one or two arguments. The first argument is the name of a table -
+** the name of a table in the RBU database.  The second, if it is present, is 1
+** for a view or 0 for a table. 
+**
+** For a non-vacuum RBU handle, if the table name matches the pattern:
+**
+**     data[0-9]_<name>
+**
+** where <name> is any sequence of 1 or more characters, <name> is returned.
+** Otherwise, if the only argument does not match the above pattern, an SQL
+** NULL is returned.
+**
+**     "data_t1"     -> "t1"
+**     "data0123_t2" -> "t2"
+**     "dataAB_t3"   -> NULL
+**
+** For an rbu vacuum handle, a copy of the first argument is returned if
+** the second argument is either missing or 0 (not a view).
+*/
+static void rbuTargetNameFunc(
+  sqlite3_context *pCtx,
+  int argc,
+  sqlite3_value **argv
+){
+  sqlite3rbu *p = sqlite3_user_data(pCtx);
+  const char *zIn;
+  assert( argc==1 || argc==2 );
+
+  zIn = (const char*)sqlite3_value_text(argv[0]);
+  if( zIn ){
+    if( rbuIsVacuum(p) ){
+      if( argc==1 || 0==sqlite3_value_int(argv[1]) ){
+        sqlite3_result_text(pCtx, zIn, -1, SQLITE_STATIC);
+      }
+    }else{
+      if( strlen(zIn)>4 && memcmp("data", zIn, 4)==0 ){
+        int i;
+        for(i=4; zIn[i]>='0' && zIn[i]<='9'; i++);
+        if( zIn[i]=='_' && zIn[i+1] ){
+          sqlite3_result_text(pCtx, &zIn[i+1], -1, SQLITE_STATIC);
+        }
+      }
+    }
+  }
+}
+
+/*
+** Initialize the iterator structure passed as the second argument.
+**
+** If no error occurs, SQLITE_OK is returned and the iterator is left 
+** pointing to the first entry. Otherwise, an error code and message is 
+** left in the RBU handle passed as the first argument. A copy of the 
+** error code is returned.
+*/
+static int rbuObjIterFirst(sqlite3rbu *p, RbuObjIter *pIter){
+  int rc;
+  memset(pIter, 0, sizeof(RbuObjIter));
+
+  rc = prepareFreeAndCollectError(p->dbRbu, &pIter->pTblIter, &p->zErrmsg, 
+    sqlite3_mprintf(
+      "SELECT rbu_target_name(name, type='view') AS target, name "
+      "FROM sqlite_master "
+      "WHERE type IN ('table', 'view') AND target IS NOT NULL "
+      " %s "
+      "ORDER BY name"
+  , rbuIsVacuum(p) ? "AND rootpage!=0 AND rootpage IS NOT NULL" : ""));
+
+  if( rc==SQLITE_OK ){
+    rc = prepareAndCollectError(p->dbMain, &pIter->pIdxIter, &p->zErrmsg,
+        "SELECT name, rootpage, sql IS NULL OR substr(8, 6)=='UNIQUE' "
+        "  FROM main.sqlite_master "
+        "  WHERE type='index' AND tbl_name = ?"
+    );
+  }
+
+  pIter->bCleanup = 1;
+  p->rc = rc;
+  return rbuObjIterNext(p, pIter);
+}
+
+/*
+** This is a wrapper around "sqlite3_mprintf(zFmt, ...)". If an OOM occurs,
+** an error code is stored in the RBU handle passed as the first argument.
+**
+** If an error has already occurred (p->rc is already set to something other
+** than SQLITE_OK), then this function returns NULL without modifying the
+** stored error code. In this case it still calls sqlite3_free() on any 
+** printf() parameters associated with %z conversions.
+*/
+static char *rbuMPrintf(sqlite3rbu *p, const char *zFmt, ...){
+  char *zSql = 0;
+  va_list ap;
+  va_start(ap, zFmt);
+  zSql = sqlite3_vmprintf(zFmt, ap);
+  if( p->rc==SQLITE_OK ){
+    if( zSql==0 ) p->rc = SQLITE_NOMEM;
+  }else{
+    sqlite3_free(zSql);
+    zSql = 0;
+  }
+  va_end(ap);
+  return zSql;
+}
+
+/*
+** Argument zFmt is a sqlite3_mprintf() style format string. The trailing
+** arguments are the usual subsitution values. This function performs
+** the printf() style substitutions and executes the result as an SQL
+** statement on the RBU handles database.
+**
+** If an error occurs, an error code and error message is stored in the
+** RBU handle. If an error has already occurred when this function is
+** called, it is a no-op.
+*/
+static int rbuMPrintfExec(sqlite3rbu *p, sqlite3 *db, const char *zFmt, ...){
+  va_list ap;
+  char *zSql;
+  va_start(ap, zFmt);
+  zSql = sqlite3_vmprintf(zFmt, ap);
+  if( p->rc==SQLITE_OK ){
+    if( zSql==0 ){
+      p->rc = SQLITE_NOMEM;
+    }else{
+      p->rc = sqlite3_exec(db, zSql, 0, 0, &p->zErrmsg);
+    }
+  }
+  sqlite3_free(zSql);
+  va_end(ap);
+  return p->rc;
+}
+
+/*
+** Attempt to allocate and return a pointer to a zeroed block of nByte 
+** bytes. 
+**
+** If an error (i.e. an OOM condition) occurs, return NULL and leave an 
+** error code in the rbu handle passed as the first argument. Or, if an 
+** error has already occurred when this function is called, return NULL 
+** immediately without attempting the allocation or modifying the stored
+** error code.
+*/
+static void *rbuMalloc(sqlite3rbu *p, int nByte){
+  void *pRet = 0;
+  if( p->rc==SQLITE_OK ){
+    assert( nByte>0 );
+    pRet = sqlite3_malloc64(nByte);
+    if( pRet==0 ){
+      p->rc = SQLITE_NOMEM;
+    }else{
+      memset(pRet, 0, nByte);
+    }
+  }
+  return pRet;
+}
+
+
+/*
+** Allocate and zero the pIter->azTblCol[] and abTblPk[] arrays so that
+** there is room for at least nCol elements. If an OOM occurs, store an
+** error code in the RBU handle passed as the first argument.
+*/
+static void rbuAllocateIterArrays(sqlite3rbu *p, RbuObjIter *pIter, int nCol){
+  int nByte = (2*sizeof(char*) + sizeof(int) + 3*sizeof(u8)) * nCol;
+  char **azNew;
+
+  azNew = (char**)rbuMalloc(p, nByte);
+  if( azNew ){
+    pIter->azTblCol = azNew;
+    pIter->azTblType = &azNew[nCol];
+    pIter->aiSrcOrder = (int*)&pIter->azTblType[nCol];
+    pIter->abTblPk = (u8*)&pIter->aiSrcOrder[nCol];
+    pIter->abNotNull = (u8*)&pIter->abTblPk[nCol];
+    pIter->abIndexed = (u8*)&pIter->abNotNull[nCol];
+  }
+}
+
+/*
+** The first argument must be a nul-terminated string. This function
+** returns a copy of the string in memory obtained from sqlite3_malloc().
+** It is the responsibility of the caller to eventually free this memory
+** using sqlite3_free().
+**
+** If an OOM condition is encountered when attempting to allocate memory,
+** output variable (*pRc) is set to SQLITE_NOMEM before returning. Otherwise,
+** if the allocation succeeds, (*pRc) is left unchanged.
+*/
+static char *rbuStrndup(const char *zStr, int *pRc){
+  char *zRet = 0;
+
+  assert( *pRc==SQLITE_OK );
+  if( zStr ){
+    size_t nCopy = strlen(zStr) + 1;
+    zRet = (char*)sqlite3_malloc64(nCopy);
+    if( zRet ){
+      memcpy(zRet, zStr, nCopy);
+    }else{
+      *pRc = SQLITE_NOMEM;
+    }
+  }
+
+  return zRet;
+}
+
+/*
+** Finalize the statement passed as the second argument.
+**
+** If the sqlite3_finalize() call indicates that an error occurs, and the
+** rbu handle error code is not already set, set the error code and error
+** message accordingly.
+*/
+static void rbuFinalize(sqlite3rbu *p, sqlite3_stmt *pStmt){
+  sqlite3 *db = sqlite3_db_handle(pStmt);
+  int rc = sqlite3_finalize(pStmt);
+  if( p->rc==SQLITE_OK && rc!=SQLITE_OK ){
+    p->rc = rc;
+    p->zErrmsg = sqlite3_mprintf("%s", sqlite3_errmsg(db));
+  }
+}
+
+/* Determine the type of a table.
+**
+**   peType is of type (int*), a pointer to an output parameter of type
+**   (int). This call sets the output parameter as follows, depending
+**   on the type of the table specified by parameters dbName and zTbl.
+**
+**     RBU_PK_NOTABLE:       No such table.
+**     RBU_PK_NONE:          Table has an implicit rowid.
+**     RBU_PK_IPK:           Table has an explicit IPK column.
+**     RBU_PK_EXTERNAL:      Table has an external PK index.
+**     RBU_PK_WITHOUT_ROWID: Table is WITHOUT ROWID.
+**     RBU_PK_VTAB:          Table is a virtual table.
+**
+**   Argument *piPk is also of type (int*), and also points to an output
+**   parameter. Unless the table has an external primary key index 
+**   (i.e. unless *peType is set to 3), then *piPk is set to zero. Or,
+**   if the table does have an external primary key index, then *piPk
+**   is set to the root page number of the primary key index before
+**   returning.
+**
+** ALGORITHM:
+**
+**   if( no entry exists in sqlite_master ){
+**     return RBU_PK_NOTABLE
+**   }else if( sql for the entry starts with "CREATE VIRTUAL" ){
+**     return RBU_PK_VTAB
+**   }else if( "PRAGMA index_list()" for the table contains a "pk" index ){
+**     if( the index that is the pk exists in sqlite_master ){
+**       *piPK = rootpage of that index.
+**       return RBU_PK_EXTERNAL
+**     }else{
+**       return RBU_PK_WITHOUT_ROWID
+**     }
+**   }else if( "PRAGMA table_info()" lists one or more "pk" columns ){
+**     return RBU_PK_IPK
+**   }else{
+**     return RBU_PK_NONE
+**   }
+*/
+static void rbuTableType(
+  sqlite3rbu *p,
+  const char *zTab,
+  int *peType,
+  int *piTnum,
+  int *piPk
+){
+  /*
+  ** 0) SELECT count(*) FROM sqlite_master where name=%Q AND IsVirtual(%Q)
+  ** 1) PRAGMA index_list = ?
+  ** 2) SELECT count(*) FROM sqlite_master where name=%Q 
+  ** 3) PRAGMA table_info = ?
+  */
+  sqlite3_stmt *aStmt[4] = {0, 0, 0, 0};
+
+  *peType = RBU_PK_NOTABLE;
+  *piPk = 0;
+
+  assert( p->rc==SQLITE_OK );
+  p->rc = prepareFreeAndCollectError(p->dbMain, &aStmt[0], &p->zErrmsg, 
+    sqlite3_mprintf(
+          "SELECT (sql LIKE 'create virtual%%'), rootpage"
+          "  FROM sqlite_master"
+          " WHERE name=%Q", zTab
+  ));
+  if( p->rc!=SQLITE_OK || sqlite3_step(aStmt[0])!=SQLITE_ROW ){
+    /* Either an error, or no such table. */
+    goto rbuTableType_end;
+  }
+  if( sqlite3_column_int(aStmt[0], 0) ){
+    *peType = RBU_PK_VTAB;                     /* virtual table */
+    goto rbuTableType_end;
+  }
+  *piTnum = sqlite3_column_int(aStmt[0], 1);
+
+  p->rc = prepareFreeAndCollectError(p->dbMain, &aStmt[1], &p->zErrmsg, 
+    sqlite3_mprintf("PRAGMA index_list=%Q",zTab)
+  );
+  if( p->rc ) goto rbuTableType_end;
+  while( sqlite3_step(aStmt[1])==SQLITE_ROW ){
+    const u8 *zOrig = sqlite3_column_text(aStmt[1], 3);
+    const u8 *zIdx = sqlite3_column_text(aStmt[1], 1);
+    if( zOrig && zIdx && zOrig[0]=='p' ){
+      p->rc = prepareFreeAndCollectError(p->dbMain, &aStmt[2], &p->zErrmsg, 
+          sqlite3_mprintf(
+            "SELECT rootpage FROM sqlite_master WHERE name = %Q", zIdx
+      ));
+      if( p->rc==SQLITE_OK ){
+        if( sqlite3_step(aStmt[2])==SQLITE_ROW ){
+          *piPk = sqlite3_column_int(aStmt[2], 0);
+          *peType = RBU_PK_EXTERNAL;
+        }else{
+          *peType = RBU_PK_WITHOUT_ROWID;
+        }
+      }
+      goto rbuTableType_end;
+    }
+  }
+
+  p->rc = prepareFreeAndCollectError(p->dbMain, &aStmt[3], &p->zErrmsg, 
+    sqlite3_mprintf("PRAGMA table_info=%Q",zTab)
+  );
+  if( p->rc==SQLITE_OK ){
+    while( sqlite3_step(aStmt[3])==SQLITE_ROW ){
+      if( sqlite3_column_int(aStmt[3],5)>0 ){
+        *peType = RBU_PK_IPK;                /* explicit IPK column */
+        goto rbuTableType_end;
+      }
+    }
+    *peType = RBU_PK_NONE;
+  }
+
+rbuTableType_end: {
+    unsigned int i;
+    for(i=0; i<sizeof(aStmt)/sizeof(aStmt[0]); i++){
+      rbuFinalize(p, aStmt[i]);
+    }
+  }
+}
+
+/*
+** This is a helper function for rbuObjIterCacheTableInfo(). It populates
+** the pIter->abIndexed[] array.
+*/
+static void rbuObjIterCacheIndexedCols(sqlite3rbu *p, RbuObjIter *pIter){
+  sqlite3_stmt *pList = 0;
+  int bIndex = 0;
+
+  if( p->rc==SQLITE_OK ){
+    memcpy(pIter->abIndexed, pIter->abTblPk, sizeof(u8)*pIter->nTblCol);
+    p->rc = prepareFreeAndCollectError(p->dbMain, &pList, &p->zErrmsg,
+        sqlite3_mprintf("PRAGMA main.index_list = %Q", pIter->zTbl)
+    );
+  }
+
+  pIter->nIndex = 0;
+  while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pList) ){
+    const char *zIdx = (const char*)sqlite3_column_text(pList, 1);
+    sqlite3_stmt *pXInfo = 0;
+    if( zIdx==0 ) break;
+    p->rc = prepareFreeAndCollectError(p->dbMain, &pXInfo, &p->zErrmsg,
+        sqlite3_mprintf("PRAGMA main.index_xinfo = %Q", zIdx)
+    );
+    while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pXInfo) ){
+      int iCid = sqlite3_column_int(pXInfo, 1);
+      if( iCid>=0 ) pIter->abIndexed[iCid] = 1;
+    }
+    rbuFinalize(p, pXInfo);
+    bIndex = 1;
+    pIter->nIndex++;
+  }
+
+  if( pIter->eType==RBU_PK_WITHOUT_ROWID ){
+    /* "PRAGMA index_list" includes the main PK b-tree */
+    pIter->nIndex--;
+  }
+
+  rbuFinalize(p, pList);
+  if( bIndex==0 ) pIter->abIndexed = 0;
+}
+
+
+/*
+** If they are not already populated, populate the pIter->azTblCol[],
+** pIter->abTblPk[], pIter->nTblCol and pIter->bRowid variables according to
+** the table (not index) that the iterator currently points to.
+**
+** Return SQLITE_OK if successful, or an SQLite error code otherwise. If
+** an error does occur, an error code and error message are also left in 
+** the RBU handle.
+*/
+static int rbuObjIterCacheTableInfo(sqlite3rbu *p, RbuObjIter *pIter){
+  if( pIter->azTblCol==0 ){
+    sqlite3_stmt *pStmt = 0;
+    int nCol = 0;
+    int i;                        /* for() loop iterator variable */
+    int bRbuRowid = 0;            /* If input table has column "rbu_rowid" */
+    int iOrder = 0;
+    int iTnum = 0;
+
+    /* Figure out the type of table this step will deal with. */
+    assert( pIter->eType==0 );
+    rbuTableType(p, pIter->zTbl, &pIter->eType, &iTnum, &pIter->iPkTnum);
+    if( p->rc==SQLITE_OK && pIter->eType==RBU_PK_NOTABLE ){
+      p->rc = SQLITE_ERROR;
+      p->zErrmsg = sqlite3_mprintf("no such table: %s", pIter->zTbl);
+    }
+    if( p->rc ) return p->rc;
+    if( pIter->zIdx==0 ) pIter->iTnum = iTnum;
+
+    assert( pIter->eType==RBU_PK_NONE || pIter->eType==RBU_PK_IPK 
+         || pIter->eType==RBU_PK_EXTERNAL || pIter->eType==RBU_PK_WITHOUT_ROWID
+         || pIter->eType==RBU_PK_VTAB
+    );
+
+    /* Populate the azTblCol[] and nTblCol variables based on the columns
+    ** of the input table. Ignore any input table columns that begin with
+    ** "rbu_".  */
+    p->rc = prepareFreeAndCollectError(p->dbRbu, &pStmt, &p->zErrmsg, 
+        sqlite3_mprintf("SELECT * FROM '%q'", pIter->zDataTbl)
+    );
+    if( p->rc==SQLITE_OK ){
+      nCol = sqlite3_column_count(pStmt);
+      rbuAllocateIterArrays(p, pIter, nCol);
+    }
+    for(i=0; p->rc==SQLITE_OK && i<nCol; i++){
+      const char *zName = (const char*)sqlite3_column_name(pStmt, i);
+      if( sqlite3_strnicmp("rbu_", zName, 4) ){
+        char *zCopy = rbuStrndup(zName, &p->rc);
+        pIter->aiSrcOrder[pIter->nTblCol] = pIter->nTblCol;
+        pIter->azTblCol[pIter->nTblCol++] = zCopy;
+      }
+      else if( 0==sqlite3_stricmp("rbu_rowid", zName) ){
+        bRbuRowid = 1;
+      }
+    }
+    sqlite3_finalize(pStmt);
+    pStmt = 0;
+
+    if( p->rc==SQLITE_OK
+     && rbuIsVacuum(p)==0
+     && bRbuRowid!=(pIter->eType==RBU_PK_VTAB || pIter->eType==RBU_PK_NONE)
+    ){
+      p->rc = SQLITE_ERROR;
+      p->zErrmsg = sqlite3_mprintf(
+          "table %q %s rbu_rowid column", pIter->zDataTbl,
+          (bRbuRowid ? "may not have" : "requires")
+      );
+    }
+
+    /* Check that all non-HIDDEN columns in the destination table are also
+    ** present in the input table. Populate the abTblPk[], azTblType[] and
+    ** aiTblOrder[] arrays at the same time.  */
+    if( p->rc==SQLITE_OK ){
+      p->rc = prepareFreeAndCollectError(p->dbMain, &pStmt, &p->zErrmsg, 
+          sqlite3_mprintf("PRAGMA table_info(%Q)", pIter->zTbl)
+      );
+    }
+    while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
+      const char *zName = (const char*)sqlite3_column_text(pStmt, 1);
+      if( zName==0 ) break;  /* An OOM - finalize() below returns S_NOMEM */
+      for(i=iOrder; i<pIter->nTblCol; i++){
+        if( 0==strcmp(zName, pIter->azTblCol[i]) ) break;
+      }
+      if( i==pIter->nTblCol ){
+        p->rc = SQLITE_ERROR;
+        p->zErrmsg = sqlite3_mprintf("column missing from %q: %s",
+            pIter->zDataTbl, zName
+        );
+      }else{
+        int iPk = sqlite3_column_int(pStmt, 5);
+        int bNotNull = sqlite3_column_int(pStmt, 3);
+        const char *zType = (const char*)sqlite3_column_text(pStmt, 2);
+
+        if( i!=iOrder ){
+          SWAP(int, pIter->aiSrcOrder[i], pIter->aiSrcOrder[iOrder]);
+          SWAP(char*, pIter->azTblCol[i], pIter->azTblCol[iOrder]);
+        }
+
+        pIter->azTblType[iOrder] = rbuStrndup(zType, &p->rc);
+        pIter->abTblPk[iOrder] = (iPk!=0);
+        pIter->abNotNull[iOrder] = (u8)bNotNull || (iPk!=0);
+        iOrder++;
+      }
+    }
+
+    rbuFinalize(p, pStmt);
+    rbuObjIterCacheIndexedCols(p, pIter);
+    assert( pIter->eType!=RBU_PK_VTAB || pIter->abIndexed==0 );
+    assert( pIter->eType!=RBU_PK_VTAB || pIter->nIndex==0 );
+  }
+
+  return p->rc;
+}
+
+/*
+** This function constructs and returns a pointer to a nul-terminated 
+** string containing some SQL clause or list based on one or more of the 
+** column names currently stored in the pIter->azTblCol[] array.
+*/
+static char *rbuObjIterGetCollist(
+  sqlite3rbu *p,                  /* RBU object */
+  RbuObjIter *pIter               /* Object iterator for column names */
+){
+  char *zList = 0;
+  const char *zSep = "";
+  int i;
+  for(i=0; i<pIter->nTblCol; i++){
+    const char *z = pIter->azTblCol[i];
+    zList = rbuMPrintf(p, "%z%s\"%w\"", zList, zSep, z);
+    zSep = ", ";
+  }
+  return zList;
+}
+
+/*
+** This function is used to create a SELECT list (the list of SQL 
+** expressions that follows a SELECT keyword) for a SELECT statement 
+** used to read from an data_xxx or rbu_tmp_xxx table while updating the 
+** index object currently indicated by the iterator object passed as the 
+** second argument. A "PRAGMA index_xinfo = <idxname>" statement is used 
+** to obtain the required information.
+**
+** If the index is of the following form:
+**
+**   CREATE INDEX i1 ON t1(c, b COLLATE nocase);
+**
+** and "t1" is a table with an explicit INTEGER PRIMARY KEY column 
+** "ipk", the returned string is:
+**
+**   "`c` COLLATE 'BINARY', `b` COLLATE 'NOCASE', `ipk` COLLATE 'BINARY'"
+**
+** As well as the returned string, three other malloc'd strings are 
+** returned via output parameters. As follows:
+**
+**   pzImposterCols: ...
+**   pzImposterPk: ...
+**   pzWhere: ...
+*/
+static char *rbuObjIterGetIndexCols(
+  sqlite3rbu *p,                  /* RBU object */
+  RbuObjIter *pIter,              /* Object iterator for column names */
+  char **pzImposterCols,          /* OUT: Columns for imposter table */
+  char **pzImposterPk,            /* OUT: Imposter PK clause */
+  char **pzWhere,                 /* OUT: WHERE clause */
+  int *pnBind                     /* OUT: Trbul number of columns */
+){
+  int rc = p->rc;                 /* Error code */
+  int rc2;                        /* sqlite3_finalize() return code */
+  char *zRet = 0;                 /* String to return */
+  char *zImpCols = 0;             /* String to return via *pzImposterCols */
+  char *zImpPK = 0;               /* String to return via *pzImposterPK */
+  char *zWhere = 0;               /* String to return via *pzWhere */
+  int nBind = 0;                  /* Value to return via *pnBind */
+  const char *zCom = "";          /* Set to ", " later on */
+  const char *zAnd = "";          /* Set to " AND " later on */
+  sqlite3_stmt *pXInfo = 0;       /* PRAGMA index_xinfo = ? */
+
+  if( rc==SQLITE_OK ){
+    assert( p->zErrmsg==0 );
+    rc = prepareFreeAndCollectError(p->dbMain, &pXInfo, &p->zErrmsg,
+        sqlite3_mprintf("PRAGMA main.index_xinfo = %Q", pIter->zIdx)
+    );
+  }
+
+  while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pXInfo) ){
+    int iCid = sqlite3_column_int(pXInfo, 1);
+    int bDesc = sqlite3_column_int(pXInfo, 3);
+    const char *zCollate = (const char*)sqlite3_column_text(pXInfo, 4);
+    const char *zCol;
+    const char *zType;
+
+    if( iCid<0 ){
+      /* An integer primary key. If the table has an explicit IPK, use
+      ** its name. Otherwise, use "rbu_rowid".  */
+      if( pIter->eType==RBU_PK_IPK ){
+        int i;
+        for(i=0; pIter->abTblPk[i]==0; i++);
+        assert( i<pIter->nTblCol );
+        zCol = pIter->azTblCol[i];
+      }else if( rbuIsVacuum(p) ){
+        zCol = "_rowid_";
+      }else{
+        zCol = "rbu_rowid";
+      }
+      zType = "INTEGER";
+    }else{
+      zCol = pIter->azTblCol[iCid];
+      zType = pIter->azTblType[iCid];
+    }
+
+    zRet = sqlite3_mprintf("%z%s\"%w\" COLLATE %Q", zRet, zCom, zCol, zCollate);
+    if( pIter->bUnique==0 || sqlite3_column_int(pXInfo, 5) ){
+      const char *zOrder = (bDesc ? " DESC" : "");
+      zImpPK = sqlite3_mprintf("%z%s\"rbu_imp_%d%w\"%s", 
+          zImpPK, zCom, nBind, zCol, zOrder
+      );
+    }
+    zImpCols = sqlite3_mprintf("%z%s\"rbu_imp_%d%w\" %s COLLATE %Q", 
+        zImpCols, zCom, nBind, zCol, zType, zCollate
+    );
+    zWhere = sqlite3_mprintf(
+        "%z%s\"rbu_imp_%d%w\" IS ?", zWhere, zAnd, nBind, zCol
+    );
+    if( zRet==0 || zImpPK==0 || zImpCols==0 || zWhere==0 ) rc = SQLITE_NOMEM;
+    zCom = ", ";
+    zAnd = " AND ";
+    nBind++;
+  }
+
+  rc2 = sqlite3_finalize(pXInfo);
+  if( rc==SQLITE_OK ) rc = rc2;
+
+  if( rc!=SQLITE_OK ){
+    sqlite3_free(zRet);
+    sqlite3_free(zImpCols);
+    sqlite3_free(zImpPK);
+    sqlite3_free(zWhere);
+    zRet = 0;
+    zImpCols = 0;
+    zImpPK = 0;
+    zWhere = 0;
+    p->rc = rc;
+  }
+
+  *pzImposterCols = zImpCols;
+  *pzImposterPk = zImpPK;
+  *pzWhere = zWhere;
+  *pnBind = nBind;
+  return zRet;
+}
+
+/*
+** Assuming the current table columns are "a", "b" and "c", and the zObj
+** paramter is passed "old", return a string of the form:
+**
+**     "old.a, old.b, old.b"
+**
+** With the column names escaped.
+**
+** For tables with implicit rowids - RBU_PK_EXTERNAL and RBU_PK_NONE, append
+** the text ", old._rowid_" to the returned value.
+*/
+static char *rbuObjIterGetOldlist(
+  sqlite3rbu *p, 
+  RbuObjIter *pIter,
+  const char *zObj
+){
+  char *zList = 0;
+  if( p->rc==SQLITE_OK && pIter->abIndexed ){
+    const char *zS = "";
+    int i;
+    for(i=0; i<pIter->nTblCol; i++){
+      if( pIter->abIndexed[i] ){
+        const char *zCol = pIter->azTblCol[i];
+        zList = sqlite3_mprintf("%z%s%s.\"%w\"", zList, zS, zObj, zCol);
+      }else{
+        zList = sqlite3_mprintf("%z%sNULL", zList, zS);
+      }
+      zS = ", ";
+      if( zList==0 ){
+        p->rc = SQLITE_NOMEM;
+        break;
+      }
+    }
+
+    /* For a table with implicit rowids, append "old._rowid_" to the list. */
+    if( pIter->eType==RBU_PK_EXTERNAL || pIter->eType==RBU_PK_NONE ){
+      zList = rbuMPrintf(p, "%z, %s._rowid_", zList, zObj);
+    }
+  }
+  return zList;
+}
+
+/*
+** Return an expression that can be used in a WHERE clause to match the
+** primary key of the current table. For example, if the table is:
+**
+**   CREATE TABLE t1(a, b, c, PRIMARY KEY(b, c));
+**
+** Return the string:
+**
+**   "b = ?1 AND c = ?2"
+*/
+static char *rbuObjIterGetWhere(
+  sqlite3rbu *p, 
+  RbuObjIter *pIter
+){
+  char *zList = 0;
+  if( pIter->eType==RBU_PK_VTAB || pIter->eType==RBU_PK_NONE ){
+    zList = rbuMPrintf(p, "_rowid_ = ?%d", pIter->nTblCol+1);
+  }else if( pIter->eType==RBU_PK_EXTERNAL ){
+    const char *zSep = "";
+    int i;
+    for(i=0; i<pIter->nTblCol; i++){
+      if( pIter->abTblPk[i] ){
+        zList = rbuMPrintf(p, "%z%sc%d=?%d", zList, zSep, i, i+1);
+        zSep = " AND ";
+      }
+    }
+    zList = rbuMPrintf(p, 
+        "_rowid_ = (SELECT id FROM rbu_imposter2 WHERE %z)", zList
+    );
+
+  }else{
+    const char *zSep = "";
+    int i;
+    for(i=0; i<pIter->nTblCol; i++){
+      if( pIter->abTblPk[i] ){
+        const char *zCol = pIter->azTblCol[i];
+        zList = rbuMPrintf(p, "%z%s\"%w\"=?%d", zList, zSep, zCol, i+1);
+        zSep = " AND ";
+      }
+    }
+  }
+  return zList;
+}
+
+/*
+** The SELECT statement iterating through the keys for the current object
+** (p->objiter.pSelect) currently points to a valid row. However, there
+** is something wrong with the rbu_control value in the rbu_control value
+** stored in the (p->nCol+1)'th column. Set the error code and error message
+** of the RBU handle to something reflecting this.
+*/
+static void rbuBadControlError(sqlite3rbu *p){
+  p->rc = SQLITE_ERROR;
+  p->zErrmsg = sqlite3_mprintf("invalid rbu_control value");
+}
+
+
+/*
+** Return a nul-terminated string containing the comma separated list of
+** assignments that should be included following the "SET" keyword of
+** an UPDATE statement used to update the table object that the iterator
+** passed as the second argument currently points to if the rbu_control
+** column of the data_xxx table entry is set to zMask.
+**
+** The memory for the returned string is obtained from sqlite3_malloc().
+** It is the responsibility of the caller to eventually free it using
+** sqlite3_free(). 
+**
+** If an OOM error is encountered when allocating space for the new
+** string, an error code is left in the rbu handle passed as the first
+** argument and NULL is returned. Or, if an error has already occurred
+** when this function is called, NULL is returned immediately, without
+** attempting the allocation or modifying the stored error code.
+*/
+static char *rbuObjIterGetSetlist(
+  sqlite3rbu *p,
+  RbuObjIter *pIter,
+  const char *zMask
+){
+  char *zList = 0;
+  if( p->rc==SQLITE_OK ){
+    int i;
+
+    if( (int)strlen(zMask)!=pIter->nTblCol ){
+      rbuBadControlError(p);
+    }else{
+      const char *zSep = "";
+      for(i=0; i<pIter->nTblCol; i++){
+        char c = zMask[pIter->aiSrcOrder[i]];
+        if( c=='x' ){
+          zList = rbuMPrintf(p, "%z%s\"%w\"=?%d", 
+              zList, zSep, pIter->azTblCol[i], i+1
+          );
+          zSep = ", ";
+        }
+        else if( c=='d' ){
+          zList = rbuMPrintf(p, "%z%s\"%w\"=rbu_delta(\"%w\", ?%d)", 
+              zList, zSep, pIter->azTblCol[i], pIter->azTblCol[i], i+1
+          );
+          zSep = ", ";
+        }
+        else if( c=='f' ){
+          zList = rbuMPrintf(p, "%z%s\"%w\"=rbu_fossil_delta(\"%w\", ?%d)", 
+              zList, zSep, pIter->azTblCol[i], pIter->azTblCol[i], i+1
+          );
+          zSep = ", ";
+        }
+      }
+    }
+  }
+  return zList;
+}
+
+/*
+** Return a nul-terminated string consisting of nByte comma separated
+** "?" expressions. For example, if nByte is 3, return a pointer to
+** a buffer containing the string "?,?,?".
+**
+** The memory for the returned string is obtained from sqlite3_malloc().
+** It is the responsibility of the caller to eventually free it using
+** sqlite3_free(). 
+**
+** If an OOM error is encountered when allocating space for the new
+** string, an error code is left in the rbu handle passed as the first
+** argument and NULL is returned. Or, if an error has already occurred
+** when this function is called, NULL is returned immediately, without
+** attempting the allocation or modifying the stored error code.
+*/
+static char *rbuObjIterGetBindlist(sqlite3rbu *p, int nBind){
+  char *zRet = 0;
+  int nByte = nBind*2 + 1;
+
+  zRet = (char*)rbuMalloc(p, nByte);
+  if( zRet ){
+    int i;
+    for(i=0; i<nBind; i++){
+      zRet[i*2] = '?';
+      zRet[i*2+1] = (i+1==nBind) ? '\0' : ',';
+    }
+  }
+  return zRet;
+}
+
+/*
+** The iterator currently points to a table (not index) of type 
+** RBU_PK_WITHOUT_ROWID. This function creates the PRIMARY KEY 
+** declaration for the corresponding imposter table. For example,
+** if the iterator points to a table created as:
+**
+**   CREATE TABLE t1(a, b, c, PRIMARY KEY(b, a DESC)) WITHOUT ROWID
+**
+** this function returns:
+**
+**   PRIMARY KEY("b", "a" DESC)
+*/
+static char *rbuWithoutRowidPK(sqlite3rbu *p, RbuObjIter *pIter){
+  char *z = 0;
+  assert( pIter->zIdx==0 );
+  if( p->rc==SQLITE_OK ){
+    const char *zSep = "PRIMARY KEY(";
+    sqlite3_stmt *pXList = 0;     /* PRAGMA index_list = (pIter->zTbl) */
+    sqlite3_stmt *pXInfo = 0;     /* PRAGMA index_xinfo = <pk-index> */
+   
+    p->rc = prepareFreeAndCollectError(p->dbMain, &pXList, &p->zErrmsg,
+        sqlite3_mprintf("PRAGMA main.index_list = %Q", pIter->zTbl)
+    );
+    while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pXList) ){
+      const char *zOrig = (const char*)sqlite3_column_text(pXList,3);
+      if( zOrig && strcmp(zOrig, "pk")==0 ){
+        const char *zIdx = (const char*)sqlite3_column_text(pXList,1);
+        if( zIdx ){
+          p->rc = prepareFreeAndCollectError(p->dbMain, &pXInfo, &p->zErrmsg,
+              sqlite3_mprintf("PRAGMA main.index_xinfo = %Q", zIdx)
+          );
+        }
+        break;
+      }
+    }
+    rbuFinalize(p, pXList);
+
+    while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pXInfo) ){
+      if( sqlite3_column_int(pXInfo, 5) ){
+        /* int iCid = sqlite3_column_int(pXInfo, 0); */
+        const char *zCol = (const char*)sqlite3_column_text(pXInfo, 2);
+        const char *zDesc = sqlite3_column_int(pXInfo, 3) ? " DESC" : "";
+        z = rbuMPrintf(p, "%z%s\"%w\"%s", z, zSep, zCol, zDesc);
+        zSep = ", ";
+      }
+    }
+    z = rbuMPrintf(p, "%z)", z);
+    rbuFinalize(p, pXInfo);
+  }
+  return z;
+}
+
+/*
+** This function creates the second imposter table used when writing to
+** a table b-tree where the table has an external primary key. If the
+** iterator passed as the second argument does not currently point to
+** a table (not index) with an external primary key, this function is a
+** no-op. 
+**
+** Assuming the iterator does point to a table with an external PK, this
+** function creates a WITHOUT ROWID imposter table named "rbu_imposter2"
+** used to access that PK index. For example, if the target table is
+** declared as follows:
+**
+**   CREATE TABLE t1(a, b TEXT, c REAL, PRIMARY KEY(b, c));
+**
+** then the imposter table schema is:
+**
+**   CREATE TABLE rbu_imposter2(c1 TEXT, c2 REAL, id INTEGER) WITHOUT ROWID;
+**
+*/
+static void rbuCreateImposterTable2(sqlite3rbu *p, RbuObjIter *pIter){
+  if( p->rc==SQLITE_OK && pIter->eType==RBU_PK_EXTERNAL ){
+    int tnum = pIter->iPkTnum;    /* Root page of PK index */
+    sqlite3_stmt *pQuery = 0;     /* SELECT name ... WHERE rootpage = $tnum */
+    const char *zIdx = 0;         /* Name of PK index */
+    sqlite3_stmt *pXInfo = 0;     /* PRAGMA main.index_xinfo = $zIdx */
+    const char *zComma = "";
+    char *zCols = 0;              /* Used to build up list of table cols */
+    char *zPk = 0;                /* Used to build up table PK declaration */
+
+    /* Figure out the name of the primary key index for the current table.
+    ** This is needed for the argument to "PRAGMA index_xinfo". Set
+    ** zIdx to point to a nul-terminated string containing this name. */
+    p->rc = prepareAndCollectError(p->dbMain, &pQuery, &p->zErrmsg, 
+        "SELECT name FROM sqlite_master WHERE rootpage = ?"
+    );
+    if( p->rc==SQLITE_OK ){
+      sqlite3_bind_int(pQuery, 1, tnum);
+      if( SQLITE_ROW==sqlite3_step(pQuery) ){
+        zIdx = (const char*)sqlite3_column_text(pQuery, 0);
+      }
+    }
+    if( zIdx ){
+      p->rc = prepareFreeAndCollectError(p->dbMain, &pXInfo, &p->zErrmsg,
+          sqlite3_mprintf("PRAGMA main.index_xinfo = %Q", zIdx)
+      );
+    }
+    rbuFinalize(p, pQuery);
+
+    while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pXInfo) ){
+      int bKey = sqlite3_column_int(pXInfo, 5);
+      if( bKey ){
+        int iCid = sqlite3_column_int(pXInfo, 1);
+        int bDesc = sqlite3_column_int(pXInfo, 3);
+        const char *zCollate = (const char*)sqlite3_column_text(pXInfo, 4);
+        zCols = rbuMPrintf(p, "%z%sc%d %s COLLATE %s", zCols, zComma, 
+            iCid, pIter->azTblType[iCid], zCollate
+        );
+        zPk = rbuMPrintf(p, "%z%sc%d%s", zPk, zComma, iCid, bDesc?" DESC":"");
+        zComma = ", ";
+      }
+    }
+    zCols = rbuMPrintf(p, "%z, id INTEGER", zCols);
+    rbuFinalize(p, pXInfo);
+
+    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 1, tnum);
+    rbuMPrintfExec(p, p->dbMain,
+        "CREATE TABLE rbu_imposter2(%z, PRIMARY KEY(%z)) WITHOUT ROWID", 
+        zCols, zPk
+    );
+    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 0, 0);
+  }
+}
+
+/*
+** If an error has already occurred when this function is called, it 
+** immediately returns zero (without doing any work). Or, if an error
+** occurs during the execution of this function, it sets the error code
+** in the sqlite3rbu object indicated by the first argument and returns
+** zero.
+**
+** The iterator passed as the second argument is guaranteed to point to
+** a table (not an index) when this function is called. This function
+** attempts to create any imposter table required to write to the main
+** table b-tree of the table before returning. Non-zero is returned if
+** an imposter table are created, or zero otherwise.
+**
+** An imposter table is required in all cases except RBU_PK_VTAB. Only
+** virtual tables are written to directly. The imposter table has the 
+** same schema as the actual target table (less any UNIQUE constraints). 
+** More precisely, the "same schema" means the same columns, types, 
+** collation sequences. For tables that do not have an external PRIMARY
+** KEY, it also means the same PRIMARY KEY declaration.
+*/
+static void rbuCreateImposterTable(sqlite3rbu *p, RbuObjIter *pIter){
+  if( p->rc==SQLITE_OK && pIter->eType!=RBU_PK_VTAB ){
+    int tnum = pIter->iTnum;
+    const char *zComma = "";
+    char *zSql = 0;
+    int iCol;
+    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 0, 1);
+
+    for(iCol=0; p->rc==SQLITE_OK && iCol<pIter->nTblCol; iCol++){
+      const char *zPk = "";
+      const char *zCol = pIter->azTblCol[iCol];
+      const char *zColl = 0;
+
+      p->rc = sqlite3_table_column_metadata(
+          p->dbMain, "main", pIter->zTbl, zCol, 0, &zColl, 0, 0, 0
+      );
+
+      if( pIter->eType==RBU_PK_IPK && pIter->abTblPk[iCol] ){
+        /* If the target table column is an "INTEGER PRIMARY KEY", add
+        ** "PRIMARY KEY" to the imposter table column declaration. */
+        zPk = "PRIMARY KEY ";
+      }
+      zSql = rbuMPrintf(p, "%z%s\"%w\" %s %sCOLLATE %s%s", 
+          zSql, zComma, zCol, pIter->azTblType[iCol], zPk, zColl,
+          (pIter->abNotNull[iCol] ? " NOT NULL" : "")
+      );
+      zComma = ", ";
+    }
+
+    if( pIter->eType==RBU_PK_WITHOUT_ROWID ){
+      char *zPk = rbuWithoutRowidPK(p, pIter);
+      if( zPk ){
+        zSql = rbuMPrintf(p, "%z, %z", zSql, zPk);
+      }
+    }
+
+    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 1, tnum);
+    rbuMPrintfExec(p, p->dbMain, "CREATE TABLE \"rbu_imp_%w\"(%z)%s", 
+        pIter->zTbl, zSql, 
+        (pIter->eType==RBU_PK_WITHOUT_ROWID ? " WITHOUT ROWID" : "")
+    );
+    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 0, 0);
+  }
+}
+
+/*
+** Prepare a statement used to insert rows into the "rbu_tmp_xxx" table.
+** Specifically a statement of the form:
+**
+**     INSERT INTO rbu_tmp_xxx VALUES(?, ?, ? ...);
+**
+** The number of bound variables is equal to the number of columns in
+** the target table, plus one (for the rbu_control column), plus one more 
+** (for the rbu_rowid column) if the target table is an implicit IPK or 
+** virtual table.
+*/
+static void rbuObjIterPrepareTmpInsert(
+  sqlite3rbu *p, 
+  RbuObjIter *pIter,
+  const char *zCollist,
+  const char *zRbuRowid
+){
+  int bRbuRowid = (pIter->eType==RBU_PK_EXTERNAL || pIter->eType==RBU_PK_NONE);
+  char *zBind = rbuObjIterGetBindlist(p, pIter->nTblCol + 1 + bRbuRowid);
+  if( zBind ){
+    assert( pIter->pTmpInsert==0 );
+    p->rc = prepareFreeAndCollectError(
+        p->dbRbu, &pIter->pTmpInsert, &p->zErrmsg, sqlite3_mprintf(
+          "INSERT INTO %s.'rbu_tmp_%q'(rbu_control,%s%s) VALUES(%z)", 
+          p->zStateDb, pIter->zDataTbl, zCollist, zRbuRowid, zBind
+    ));
+  }
+}
+
+static void rbuTmpInsertFunc(
+  sqlite3_context *pCtx, 
+  int nVal,
+  sqlite3_value **apVal
+){
+  sqlite3rbu *p = sqlite3_user_data(pCtx);
+  int rc = SQLITE_OK;
+  int i;
+
+  assert( sqlite3_value_int(apVal[0])!=0
+      || p->objiter.eType==RBU_PK_EXTERNAL 
+      || p->objiter.eType==RBU_PK_NONE 
+  );
+  if( sqlite3_value_int(apVal[0])!=0 ){
+    p->nPhaseOneStep += p->objiter.nIndex;
+  }
+
+  for(i=0; rc==SQLITE_OK && i<nVal; i++){
+    rc = sqlite3_bind_value(p->objiter.pTmpInsert, i+1, apVal[i]);
+  }
+  if( rc==SQLITE_OK ){
+    sqlite3_step(p->objiter.pTmpInsert);
+    rc = sqlite3_reset(p->objiter.pTmpInsert);
+  }
+
+  if( rc!=SQLITE_OK ){
+    sqlite3_result_error_code(pCtx, rc);
+  }
+}
+
+/*
+** Ensure that the SQLite statement handles required to update the 
+** target database object currently indicated by the iterator passed 
+** as the second argument are available.
+*/
+static int rbuObjIterPrepareAll(
+  sqlite3rbu *p, 
+  RbuObjIter *pIter,
+  int nOffset                     /* Add "LIMIT -1 OFFSET $nOffset" to SELECT */
+){
+  assert( pIter->bCleanup==0 );
+  if( pIter->pSelect==0 && rbuObjIterCacheTableInfo(p, pIter)==SQLITE_OK ){
+    const int tnum = pIter->iTnum;
+    char *zCollist = 0;           /* List of indexed columns */
+    char **pz = &p->zErrmsg;
+    const char *zIdx = pIter->zIdx;
+    char *zLimit = 0;
+
+    if( nOffset ){
+      zLimit = sqlite3_mprintf(" LIMIT -1 OFFSET %d", nOffset);
+      if( !zLimit ) p->rc = SQLITE_NOMEM;
+    }
+
+    if( zIdx ){
+      const char *zTbl = pIter->zTbl;
+      char *zImposterCols = 0;    /* Columns for imposter table */
+      char *zImposterPK = 0;      /* Primary key declaration for imposter */
+      char *zWhere = 0;           /* WHERE clause on PK columns */
+      char *zBind = 0;
+      int nBind = 0;
+
+      assert( pIter->eType!=RBU_PK_VTAB );
+      zCollist = rbuObjIterGetIndexCols(
+          p, pIter, &zImposterCols, &zImposterPK, &zWhere, &nBind
+      );
+      zBind = rbuObjIterGetBindlist(p, nBind);
+
+      /* Create the imposter table used to write to this index. */
+      sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 0, 1);
+      sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 1,tnum);
+      rbuMPrintfExec(p, p->dbMain,
+          "CREATE TABLE \"rbu_imp_%w\"( %s, PRIMARY KEY( %s ) ) WITHOUT ROWID",
+          zTbl, zImposterCols, zImposterPK
+      );
+      sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 0, 0);
+
+      /* Create the statement to insert index entries */
+      pIter->nCol = nBind;
+      if( p->rc==SQLITE_OK ){
+        p->rc = prepareFreeAndCollectError(
+            p->dbMain, &pIter->pInsert, &p->zErrmsg,
+          sqlite3_mprintf("INSERT INTO \"rbu_imp_%w\" VALUES(%s)", zTbl, zBind)
+        );
+      }
+
+      /* And to delete index entries */
+      if( rbuIsVacuum(p)==0 && p->rc==SQLITE_OK ){
+        p->rc = prepareFreeAndCollectError(
+            p->dbMain, &pIter->pDelete, &p->zErrmsg,
+          sqlite3_mprintf("DELETE FROM \"rbu_imp_%w\" WHERE %s", zTbl, zWhere)
+        );
+      }
+
+      /* Create the SELECT statement to read keys in sorted order */
+      if( p->rc==SQLITE_OK ){
+        char *zSql;
+        if( rbuIsVacuum(p) ){
+          zSql = sqlite3_mprintf(
+              "SELECT %s, 0 AS rbu_control FROM '%q' ORDER BY %s%s",
+              zCollist, 
+              pIter->zDataTbl,
+              zCollist, zLimit
+          );
+        }else
+
+        if( pIter->eType==RBU_PK_EXTERNAL || pIter->eType==RBU_PK_NONE ){
+          zSql = sqlite3_mprintf(
+              "SELECT %s, rbu_control FROM %s.'rbu_tmp_%q' ORDER BY %s%s",
+              zCollist, p->zStateDb, pIter->zDataTbl,
+              zCollist, zLimit
+          );
+        }else{
+          zSql = sqlite3_mprintf(
+              "SELECT %s, rbu_control FROM %s.'rbu_tmp_%q' "
+              "UNION ALL "
+              "SELECT %s, rbu_control FROM '%q' "
+              "WHERE typeof(rbu_control)='integer' AND rbu_control!=1 "
+              "ORDER BY %s%s",
+              zCollist, p->zStateDb, pIter->zDataTbl, 
+              zCollist, pIter->zDataTbl, 
+              zCollist, zLimit
+          );
+        }
+        p->rc = prepareFreeAndCollectError(p->dbRbu, &pIter->pSelect, pz, zSql);
+      }
+
+      sqlite3_free(zImposterCols);
+      sqlite3_free(zImposterPK);
+      sqlite3_free(zWhere);
+      sqlite3_free(zBind);
+    }else{
+      int bRbuRowid = (pIter->eType==RBU_PK_VTAB)
+                    ||(pIter->eType==RBU_PK_NONE)
+                    ||(pIter->eType==RBU_PK_EXTERNAL && rbuIsVacuum(p));
+      const char *zTbl = pIter->zTbl;       /* Table this step applies to */
+      const char *zWrite;                   /* Imposter table name */
+
+      char *zBindings = rbuObjIterGetBindlist(p, pIter->nTblCol + bRbuRowid);
+      char *zWhere = rbuObjIterGetWhere(p, pIter);
+      char *zOldlist = rbuObjIterGetOldlist(p, pIter, "old");
+      char *zNewlist = rbuObjIterGetOldlist(p, pIter, "new");
+
+      zCollist = rbuObjIterGetCollist(p, pIter);
+      pIter->nCol = pIter->nTblCol;
+
+      /* Create the imposter table or tables (if required). */
+      rbuCreateImposterTable(p, pIter);
+      rbuCreateImposterTable2(p, pIter);
+      zWrite = (pIter->eType==RBU_PK_VTAB ? "" : "rbu_imp_");
+
+      /* Create the INSERT statement to write to the target PK b-tree */
+      if( p->rc==SQLITE_OK ){
+        p->rc = prepareFreeAndCollectError(p->dbMain, &pIter->pInsert, pz,
+            sqlite3_mprintf(
+              "INSERT INTO \"%s%w\"(%s%s) VALUES(%s)", 
+              zWrite, zTbl, zCollist, (bRbuRowid ? ", _rowid_" : ""), zBindings
+            )
+        );
+      }
+
+      /* Create the DELETE statement to write to the target PK b-tree.
+      ** Because it only performs INSERT operations, this is not required for
+      ** an rbu vacuum handle.  */
+      if( rbuIsVacuum(p)==0 && p->rc==SQLITE_OK ){
+        p->rc = prepareFreeAndCollectError(p->dbMain, &pIter->pDelete, pz,
+            sqlite3_mprintf(
+              "DELETE FROM \"%s%w\" WHERE %s", zWrite, zTbl, zWhere
+            )
+        );
+      }
+
+      if( rbuIsVacuum(p)==0 && pIter->abIndexed ){
+        const char *zRbuRowid = "";
+        if( pIter->eType==RBU_PK_EXTERNAL || pIter->eType==RBU_PK_NONE ){
+          zRbuRowid = ", rbu_rowid";
+        }
+
+        /* Create the rbu_tmp_xxx table and the triggers to populate it. */
+        rbuMPrintfExec(p, p->dbRbu,
+            "CREATE TABLE IF NOT EXISTS %s.'rbu_tmp_%q' AS "
+            "SELECT *%s FROM '%q' WHERE 0;"
+            , p->zStateDb, pIter->zDataTbl
+            , (pIter->eType==RBU_PK_EXTERNAL ? ", 0 AS rbu_rowid" : "")
+            , pIter->zDataTbl
+        );
+
+        rbuMPrintfExec(p, p->dbMain,
+            "CREATE TEMP TRIGGER rbu_delete_tr BEFORE DELETE ON \"%s%w\" "
+            "BEGIN "
+            "  SELECT rbu_tmp_insert(3, %s);"
+            "END;"
+
+            "CREATE TEMP TRIGGER rbu_update1_tr BEFORE UPDATE ON \"%s%w\" "
+            "BEGIN "
+            "  SELECT rbu_tmp_insert(3, %s);"
+            "END;"
+
+            "CREATE TEMP TRIGGER rbu_update2_tr AFTER UPDATE ON \"%s%w\" "
+            "BEGIN "
+            "  SELECT rbu_tmp_insert(4, %s);"
+            "END;",
+            zWrite, zTbl, zOldlist,
+            zWrite, zTbl, zOldlist,
+            zWrite, zTbl, zNewlist
+        );
+
+        if( pIter->eType==RBU_PK_EXTERNAL || pIter->eType==RBU_PK_NONE ){
+          rbuMPrintfExec(p, p->dbMain,
+              "CREATE TEMP TRIGGER rbu_insert_tr AFTER INSERT ON \"%s%w\" "
+              "BEGIN "
+              "  SELECT rbu_tmp_insert(0, %s);"
+              "END;",
+              zWrite, zTbl, zNewlist
+          );
+        }
+
+        rbuObjIterPrepareTmpInsert(p, pIter, zCollist, zRbuRowid);
+      }
+
+      /* Create the SELECT statement to read keys from data_xxx */
+      if( p->rc==SQLITE_OK ){
+        const char *zRbuRowid = "";
+        if( bRbuRowid ){
+          zRbuRowid = rbuIsVacuum(p) ? ",_rowid_ " : ",rbu_rowid";
+        }
+        p->rc = prepareFreeAndCollectError(p->dbRbu, &pIter->pSelect, pz,
+            sqlite3_mprintf(
+              "SELECT %s,%s rbu_control%s FROM '%q'%s", 
+              zCollist, 
+              (rbuIsVacuum(p) ? "0 AS " : ""),
+              zRbuRowid,
+              pIter->zDataTbl, zLimit
+            )
+        );
+      }
+
+      sqlite3_free(zWhere);
+      sqlite3_free(zOldlist);
+      sqlite3_free(zNewlist);
+      sqlite3_free(zBindings);
+    }
+    sqlite3_free(zCollist);
+    sqlite3_free(zLimit);
+  }
+  
+  return p->rc;
+}
+
+/*
+** Set output variable *ppStmt to point to an UPDATE statement that may
+** be used to update the imposter table for the main table b-tree of the
+** table object that pIter currently points to, assuming that the 
+** rbu_control column of the data_xyz table contains zMask.
+** 
+** If the zMask string does not specify any columns to update, then this
+** is not an error. Output variable *ppStmt is set to NULL in this case.
+*/
+static int rbuGetUpdateStmt(
+  sqlite3rbu *p,                  /* RBU handle */
+  RbuObjIter *pIter,              /* Object iterator */
+  const char *zMask,              /* rbu_control value ('x.x.') */
+  sqlite3_stmt **ppStmt           /* OUT: UPDATE statement handle */
+){
+  RbuUpdateStmt **pp;
+  RbuUpdateStmt *pUp = 0;
+  int nUp = 0;
+
+  /* In case an error occurs */
+  *ppStmt = 0;
+
+  /* Search for an existing statement. If one is found, shift it to the front
+  ** of the LRU queue and return immediately. Otherwise, leave nUp pointing
+  ** to the number of statements currently in the cache and pUp to the
+  ** last object in the list.  */
+  for(pp=&pIter->pRbuUpdate; *pp; pp=&((*pp)->pNext)){
+    pUp = *pp;
+    if( strcmp(pUp->zMask, zMask)==0 ){
+      *pp = pUp->pNext;
+      pUp->pNext = pIter->pRbuUpdate;
+      pIter->pRbuUpdate = pUp;
+      *ppStmt = pUp->pUpdate; 
+      return SQLITE_OK;
+    }
+    nUp++;
+  }
+  assert( pUp==0 || pUp->pNext==0 );
+
+  if( nUp>=SQLITE_RBU_UPDATE_CACHESIZE ){
+    for(pp=&pIter->pRbuUpdate; *pp!=pUp; pp=&((*pp)->pNext));
+    *pp = 0;
+    sqlite3_finalize(pUp->pUpdate);
+    pUp->pUpdate = 0;
+  }else{
+    pUp = (RbuUpdateStmt*)rbuMalloc(p, sizeof(RbuUpdateStmt)+pIter->nTblCol+1);
+  }
+
+  if( pUp ){
+    char *zWhere = rbuObjIterGetWhere(p, pIter);
+    char *zSet = rbuObjIterGetSetlist(p, pIter, zMask);
+    char *zUpdate = 0;
+
+    pUp->zMask = (char*)&pUp[1];
+    memcpy(pUp->zMask, zMask, pIter->nTblCol);
+    pUp->pNext = pIter->pRbuUpdate;
+    pIter->pRbuUpdate = pUp;
+
+    if( zSet ){
+      const char *zPrefix = "";
+
+      if( pIter->eType!=RBU_PK_VTAB ) zPrefix = "rbu_imp_";
+      zUpdate = sqlite3_mprintf("UPDATE \"%s%w\" SET %s WHERE %s", 
+          zPrefix, pIter->zTbl, zSet, zWhere
+      );
+      p->rc = prepareFreeAndCollectError(
+          p->dbMain, &pUp->pUpdate, &p->zErrmsg, zUpdate
+      );
+      *ppStmt = pUp->pUpdate;
+    }
+    sqlite3_free(zWhere);
+    sqlite3_free(zSet);
+  }
+
+  return p->rc;
+}
+
+static sqlite3 *rbuOpenDbhandle(
+  sqlite3rbu *p, 
+  const char *zName, 
+  int bUseVfs
+){
+  sqlite3 *db = 0;
+  if( p->rc==SQLITE_OK ){
+    const int flags = SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|SQLITE_OPEN_URI;
+    p->rc = sqlite3_open_v2(zName, &db, flags, bUseVfs ? p->zVfsName : 0);
+    if( p->rc ){
+      p->zErrmsg = sqlite3_mprintf("%s", sqlite3_errmsg(db));
+      sqlite3_close(db);
+      db = 0;
+    }
+  }
+  return db;
+}
+
+/*
+** Free an RbuState object allocated by rbuLoadState().
+*/
+static void rbuFreeState(RbuState *p){
+  if( p ){
+    sqlite3_free(p->zTbl);
+    sqlite3_free(p->zIdx);
+    sqlite3_free(p);
+  }
+}
+
+/*
+** Allocate an RbuState object and load the contents of the rbu_state 
+** table into it. Return a pointer to the new object. It is the 
+** responsibility of the caller to eventually free the object using
+** sqlite3_free().
+**
+** If an error occurs, leave an error code and message in the rbu handle
+** and return NULL.
+*/
+static RbuState *rbuLoadState(sqlite3rbu *p){
+  RbuState *pRet = 0;
+  sqlite3_stmt *pStmt = 0;
+  int rc;
+  int rc2;
+
+  pRet = (RbuState*)rbuMalloc(p, sizeof(RbuState));
+  if( pRet==0 ) return 0;
+
+  rc = prepareFreeAndCollectError(p->dbRbu, &pStmt, &p->zErrmsg, 
+      sqlite3_mprintf("SELECT k, v FROM %s.rbu_state", p->zStateDb)
+  );
+  while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
+    switch( sqlite3_column_int(pStmt, 0) ){
+      case RBU_STATE_STAGE:
+        pRet->eStage = sqlite3_column_int(pStmt, 1);
+        if( pRet->eStage!=RBU_STAGE_OAL
+         && pRet->eStage!=RBU_STAGE_MOVE
+         && pRet->eStage!=RBU_STAGE_CKPT
+        ){
+          p->rc = SQLITE_CORRUPT;
+        }
+        break;
+
+      case RBU_STATE_TBL:
+        pRet->zTbl = rbuStrndup((char*)sqlite3_column_text(pStmt, 1), &rc);
+        break;
+
+      case RBU_STATE_IDX:
+        pRet->zIdx = rbuStrndup((char*)sqlite3_column_text(pStmt, 1), &rc);
+        break;
+
+      case RBU_STATE_ROW:
+        pRet->nRow = sqlite3_column_int(pStmt, 1);
+        break;
+
+      case RBU_STATE_PROGRESS:
+        pRet->nProgress = sqlite3_column_int64(pStmt, 1);
+        break;
+
+      case RBU_STATE_CKPT:
+        pRet->iWalCksum = sqlite3_column_int64(pStmt, 1);
+        break;
+
+      case RBU_STATE_COOKIE:
+        pRet->iCookie = (u32)sqlite3_column_int64(pStmt, 1);
+        break;
+
+      case RBU_STATE_OALSZ:
+        pRet->iOalSz = (u32)sqlite3_column_int64(pStmt, 1);
+        break;
+
+      case RBU_STATE_PHASEONESTEP:
+        pRet->nPhaseOneStep = sqlite3_column_int64(pStmt, 1);
+        break;
+
+      default:
+        rc = SQLITE_CORRUPT;
+        break;
+    }
+  }
+  rc2 = sqlite3_finalize(pStmt);
+  if( rc==SQLITE_OK ) rc = rc2;
+
+  p->rc = rc;
+  return pRet;
+}
+
+
+/*
+** Open the database handle and attach the RBU database as "rbu". If an
+** error occurs, leave an error code and message in the RBU handle.
+*/
+static void rbuOpenDatabase(sqlite3rbu *p){
+  assert( p->rc || (p->dbMain==0 && p->dbRbu==0) );
+  assert( p->rc || rbuIsVacuum(p) || p->zTarget!=0 );
+
+  /* Open the RBU database */
+  p->dbRbu = rbuOpenDbhandle(p, p->zRbu, 1);
+
+  if( p->rc==SQLITE_OK && rbuIsVacuum(p) ){
+    sqlite3_file_control(p->dbRbu, "main", SQLITE_FCNTL_RBUCNT, (void*)p);
+    if( p->zState==0 ){
+      const char *zFile = sqlite3_db_filename(p->dbRbu, "main");
+      p->zState = rbuMPrintf(p, "file://%s-vacuum?modeof=%s", zFile, zFile);
+    }
+  }
+
+  /* If using separate RBU and state databases, attach the state database to
+  ** the RBU db handle now.  */
+  if( p->zState ){
+    rbuMPrintfExec(p, p->dbRbu, "ATTACH %Q AS stat", p->zState);
+    memcpy(p->zStateDb, "stat", 4);
+  }else{
+    memcpy(p->zStateDb, "main", 4);
+  }
+
+#if 0
+  if( p->rc==SQLITE_OK && rbuIsVacuum(p) ){
+    p->rc = sqlite3_exec(p->dbRbu, "BEGIN", 0, 0, 0);
+  }
+#endif
+
+  /* If it has not already been created, create the rbu_state table */
+  rbuMPrintfExec(p, p->dbRbu, RBU_CREATE_STATE, p->zStateDb);
+
+#if 0
+  if( rbuIsVacuum(p) ){
+    if( p->rc==SQLITE_OK ){
+      int rc2;
+      int bOk = 0;
+      sqlite3_stmt *pCnt = 0;
+      p->rc = prepareAndCollectError(p->dbRbu, &pCnt, &p->zErrmsg,
+          "SELECT count(*) FROM stat.sqlite_master"
+      );
+      if( p->rc==SQLITE_OK 
+       && sqlite3_step(pCnt)==SQLITE_ROW
+       && 1==sqlite3_column_int(pCnt, 0)
+      ){
+        bOk = 1;
+      }
+      rc2 = sqlite3_finalize(pCnt);
+      if( p->rc==SQLITE_OK ) p->rc = rc2;
+
+      if( p->rc==SQLITE_OK && bOk==0 ){
+        p->rc = SQLITE_ERROR;
+        p->zErrmsg = sqlite3_mprintf("invalid state database");
+      }
+    
+      if( p->rc==SQLITE_OK ){
+        p->rc = sqlite3_exec(p->dbRbu, "COMMIT", 0, 0, 0);
+      }
+    }
+  }
+#endif
+
+  if( p->rc==SQLITE_OK && rbuIsVacuum(p) ){
+    int bOpen = 0;
+    int rc;
+    p->nRbu = 0;
+    p->pRbuFd = 0;
+    rc = sqlite3_file_control(p->dbRbu, "main", SQLITE_FCNTL_RBUCNT, (void*)p);
+    if( rc!=SQLITE_NOTFOUND ) p->rc = rc;
+    if( p->eStage>=RBU_STAGE_MOVE ){
+      bOpen = 1;
+    }else{
+      RbuState *pState = rbuLoadState(p);
+      if( pState ){
+        bOpen = (pState->eStage>RBU_STAGE_MOVE);
+        rbuFreeState(pState);
+      }
+    }
+    if( bOpen ) p->dbMain = rbuOpenDbhandle(p, p->zRbu, p->nRbu<=1);
+  }
+
+  p->eStage = 0;
+  if( p->rc==SQLITE_OK && p->dbMain==0 ){
+    if( !rbuIsVacuum(p) ){
+      p->dbMain = rbuOpenDbhandle(p, p->zTarget, 1);
+    }else if( p->pRbuFd->pWalFd ){
+      p->rc = SQLITE_ERROR;
+      p->zErrmsg = sqlite3_mprintf("cannot vacuum wal mode database");
+    }else{
+      char *zTarget;
+      char *zExtra = 0;
+      if( strlen(p->zRbu)>=5 && 0==memcmp("file:", p->zRbu, 5) ){
+        zExtra = &p->zRbu[5];
+        while( *zExtra ){
+          if( *zExtra++=='?' ) break;
+        }
+        if( *zExtra=='\0' ) zExtra = 0;
+      }
+
+      zTarget = sqlite3_mprintf("file:%s-vacuum?rbu_memory=1%s%s", 
+          sqlite3_db_filename(p->dbRbu, "main"),
+          (zExtra==0 ? "" : "&"), (zExtra==0 ? "" : zExtra)
+      );
+
+      if( zTarget==0 ){
+        p->rc = SQLITE_NOMEM;
+        return;
+      }
+      p->dbMain = rbuOpenDbhandle(p, zTarget, p->nRbu<=1);
+      sqlite3_free(zTarget);
+    }
+  }
+
+  if( p->rc==SQLITE_OK ){
+    p->rc = sqlite3_create_function(p->dbMain, 
+        "rbu_tmp_insert", -1, SQLITE_UTF8, (void*)p, rbuTmpInsertFunc, 0, 0
+    );
+  }
+
+  if( p->rc==SQLITE_OK ){
+    p->rc = sqlite3_create_function(p->dbMain, 
+        "rbu_fossil_delta", 2, SQLITE_UTF8, 0, rbuFossilDeltaFunc, 0, 0
+    );
+  }
+
+  if( p->rc==SQLITE_OK ){
+    p->rc = sqlite3_create_function(p->dbRbu, 
+        "rbu_target_name", -1, SQLITE_UTF8, (void*)p, rbuTargetNameFunc, 0, 0
+    );
+  }
+
+  if( p->rc==SQLITE_OK ){
+    p->rc = sqlite3_file_control(p->dbMain, "main", SQLITE_FCNTL_RBU, (void*)p);
+  }
+  rbuMPrintfExec(p, p->dbMain, "SELECT * FROM sqlite_master");
+
+  /* Mark the database file just opened as an RBU target database. If 
+  ** this call returns SQLITE_NOTFOUND, then the RBU vfs is not in use.
+  ** This is an error.  */
+  if( p->rc==SQLITE_OK ){
+    p->rc = sqlite3_file_control(p->dbMain, "main", SQLITE_FCNTL_RBU, (void*)p);
+  }
+
+  if( p->rc==SQLITE_NOTFOUND ){
+    p->rc = SQLITE_ERROR;
+    p->zErrmsg = sqlite3_mprintf("rbu vfs not found");
+  }
+}
+
+/*
+** This routine is a copy of the sqlite3FileSuffix3() routine from the core.
+** It is a no-op unless SQLITE_ENABLE_8_3_NAMES is defined.
+**
+** If SQLITE_ENABLE_8_3_NAMES is set at compile-time and if the database
+** filename in zBaseFilename is a URI with the "8_3_names=1" parameter and
+** if filename in z[] has a suffix (a.k.a. "extension") that is longer than
+** three characters, then shorten the suffix on z[] to be the last three
+** characters of the original suffix.
+**
+** If SQLITE_ENABLE_8_3_NAMES is set to 2 at compile-time, then always
+** do the suffix shortening regardless of URI parameter.
+**
+** Examples:
+**
+**     test.db-journal    =>   test.nal
+**     test.db-wal        =>   test.wal
+**     test.db-shm        =>   test.shm
+**     test.db-mj7f3319fa =>   test.9fa
+*/
+static void rbuFileSuffix3(const char *zBase, char *z){
+#ifdef SQLITE_ENABLE_8_3_NAMES
+#if SQLITE_ENABLE_8_3_NAMES<2
+  if( sqlite3_uri_boolean(zBase, "8_3_names", 0) )
+#endif
+  {
+    int i, sz;
+    sz = (int)strlen(z)&0xffffff;
+    for(i=sz-1; i>0 && z[i]!='/' && z[i]!='.'; i--){}
+    if( z[i]=='.' && sz>i+4 ) memmove(&z[i+1], &z[sz-3], 4);
+  }
+#endif
+}
+
+/*
+** Return the current wal-index header checksum for the target database 
+** as a 64-bit integer.
+**
+** The checksum is store in the first page of xShmMap memory as an 8-byte 
+** blob starting at byte offset 40.
+*/
+static i64 rbuShmChecksum(sqlite3rbu *p){
+  i64 iRet = 0;
+  if( p->rc==SQLITE_OK ){
+    sqlite3_file *pDb = p->pTargetFd->pReal;
+    u32 volatile *ptr;
+    p->rc = pDb->pMethods->xShmMap(pDb, 0, 32*1024, 0, (void volatile**)&ptr);
+    if( p->rc==SQLITE_OK ){
+      iRet = ((i64)ptr[10] << 32) + ptr[11];
+    }
+  }
+  return iRet;
+}
+
+/*
+** This function is called as part of initializing or reinitializing an
+** incremental checkpoint. 
+**
+** It populates the sqlite3rbu.aFrame[] array with the set of 
+** (wal frame -> db page) copy operations required to checkpoint the 
+** current wal file, and obtains the set of shm locks required to safely 
+** perform the copy operations directly on the file-system.
+**
+** If argument pState is not NULL, then the incremental checkpoint is
+** being resumed. In this case, if the checksum of the wal-index-header
+** following recovery is not the same as the checksum saved in the RbuState
+** object, then the rbu handle is set to DONE state. This occurs if some
+** other client appends a transaction to the wal file in the middle of
+** an incremental checkpoint.
+*/
+static void rbuSetupCheckpoint(sqlite3rbu *p, RbuState *pState){
+
+  /* If pState is NULL, then the wal file may not have been opened and
+  ** recovered. Running a read-statement here to ensure that doing so
+  ** does not interfere with the "capture" process below.  */
+  if( pState==0 ){
+    p->eStage = 0;
+    if( p->rc==SQLITE_OK ){
+      p->rc = sqlite3_exec(p->dbMain, "SELECT * FROM sqlite_master", 0, 0, 0);
+    }
+  }
+
+  /* Assuming no error has occurred, run a "restart" checkpoint with the
+  ** sqlite3rbu.eStage variable set to CAPTURE. This turns on the following
+  ** special behaviour in the rbu VFS:
+  **
+  **   * If the exclusive shm WRITER or READ0 lock cannot be obtained,
+  **     the checkpoint fails with SQLITE_BUSY (normally SQLite would
+  **     proceed with running a passive checkpoint instead of failing).
+  **
+  **   * Attempts to read from the *-wal file or write to the database file
+  **     do not perform any IO. Instead, the frame/page combinations that
+  **     would be read/written are recorded in the sqlite3rbu.aFrame[]
+  **     array.
+  **
+  **   * Calls to xShmLock(UNLOCK) to release the exclusive shm WRITER, 
+  **     READ0 and CHECKPOINT locks taken as part of the checkpoint are
+  **     no-ops. These locks will not be released until the connection
+  **     is closed.
+  **
+  **   * Attempting to xSync() the database file causes an SQLITE_INTERNAL 
+  **     error.
+  **
+  ** As a result, unless an error (i.e. OOM or SQLITE_BUSY) occurs, the
+  ** checkpoint below fails with SQLITE_INTERNAL, and leaves the aFrame[]
+  ** array populated with a set of (frame -> page) mappings. Because the 
+  ** WRITER, CHECKPOINT and READ0 locks are still held, it is safe to copy 
+  ** data from the wal file into the database file according to the 
+  ** contents of aFrame[].
+  */
+  if( p->rc==SQLITE_OK ){
+    int rc2;
+    p->eStage = RBU_STAGE_CAPTURE;
+    rc2 = sqlite3_exec(p->dbMain, "PRAGMA main.wal_checkpoint=restart", 0, 0,0);
+    if( rc2!=SQLITE_INTERNAL ) p->rc = rc2;
+  }
+
+  if( p->rc==SQLITE_OK ){
+    p->eStage = RBU_STAGE_CKPT;
+    p->nStep = (pState ? pState->nRow : 0);
+    p->aBuf = rbuMalloc(p, p->pgsz);
+    p->iWalCksum = rbuShmChecksum(p);
+  }
+
+  if( p->rc==SQLITE_OK && pState && pState->iWalCksum!=p->iWalCksum ){
+    p->rc = SQLITE_DONE;
+    p->eStage = RBU_STAGE_DONE;
+  }
+}
+
+/*
+** Called when iAmt bytes are read from offset iOff of the wal file while
+** the rbu object is in capture mode. Record the frame number of the frame
+** being read in the aFrame[] array.
+*/
+static int rbuCaptureWalRead(sqlite3rbu *pRbu, i64 iOff, int iAmt){
+  const u32 mReq = (1<<WAL_LOCK_WRITE)|(1<<WAL_LOCK_CKPT)|(1<<WAL_LOCK_READ0);
+  u32 iFrame;
+
+  if( pRbu->mLock!=mReq ){
+    pRbu->rc = SQLITE_BUSY;
+    return SQLITE_INTERNAL;
+  }
+
+  pRbu->pgsz = iAmt;
+  if( pRbu->nFrame==pRbu->nFrameAlloc ){
+    int nNew = (pRbu->nFrameAlloc ? pRbu->nFrameAlloc : 64) * 2;
+    RbuFrame *aNew;
+    aNew = (RbuFrame*)sqlite3_realloc64(pRbu->aFrame, nNew * sizeof(RbuFrame));
+    if( aNew==0 ) return SQLITE_NOMEM;
+    pRbu->aFrame = aNew;
+    pRbu->nFrameAlloc = nNew;
+  }
+
+  iFrame = (u32)((iOff-32) / (i64)(iAmt+24)) + 1;
+  if( pRbu->iMaxFrame<iFrame ) pRbu->iMaxFrame = iFrame;
+  pRbu->aFrame[pRbu->nFrame].iWalFrame = iFrame;
+  pRbu->aFrame[pRbu->nFrame].iDbPage = 0;
+  pRbu->nFrame++;
+  return SQLITE_OK;
+}
+
+/*
+** Called when a page of data is written to offset iOff of the database
+** file while the rbu handle is in capture mode. Record the page number 
+** of the page being written in the aFrame[] array.
+*/
+static int rbuCaptureDbWrite(sqlite3rbu *pRbu, i64 iOff){
+  pRbu->aFrame[pRbu->nFrame-1].iDbPage = (u32)(iOff / pRbu->pgsz) + 1;
+  return SQLITE_OK;
+}
+
+/*
+** This is called as part of an incremental checkpoint operation. Copy
+** a single frame of data from the wal file into the database file, as
+** indicated by the RbuFrame object.
+*/
+static void rbuCheckpointFrame(sqlite3rbu *p, RbuFrame *pFrame){
+  sqlite3_file *pWal = p->pTargetFd->pWalFd->pReal;
+  sqlite3_file *pDb = p->pTargetFd->pReal;
+  i64 iOff;
+
+  assert( p->rc==SQLITE_OK );
+  iOff = (i64)(pFrame->iWalFrame-1) * (p->pgsz + 24) + 32 + 24;
+  p->rc = pWal->pMethods->xRead(pWal, p->aBuf, p->pgsz, iOff);
+  if( p->rc ) return;
+
+  iOff = (i64)(pFrame->iDbPage-1) * p->pgsz;
+  p->rc = pDb->pMethods->xWrite(pDb, p->aBuf, p->pgsz, iOff);
+}
+
+
+/*
+** Take an EXCLUSIVE lock on the database file.
+*/
+static void rbuLockDatabase(sqlite3rbu *p){
+  sqlite3_file *pReal = p->pTargetFd->pReal;
+  assert( p->rc==SQLITE_OK );
+  p->rc = pReal->pMethods->xLock(pReal, SQLITE_LOCK_SHARED);
+  if( p->rc==SQLITE_OK ){
+    p->rc = pReal->pMethods->xLock(pReal, SQLITE_LOCK_EXCLUSIVE);
+  }
+}
+
+#if defined(_WIN32_WCE)
+static LPWSTR rbuWinUtf8ToUnicode(const char *zFilename){
+  int nChar;
+  LPWSTR zWideFilename;
+
+  nChar = MultiByteToWideChar(CP_UTF8, 0, zFilename, -1, NULL, 0);
+  if( nChar==0 ){
+    return 0;
+  }
+  zWideFilename = sqlite3_malloc64( nChar*sizeof(zWideFilename[0]) );
+  if( zWideFilename==0 ){
+    return 0;
+  }
+  memset(zWideFilename, 0, nChar*sizeof(zWideFilename[0]));
+  nChar = MultiByteToWideChar(CP_UTF8, 0, zFilename, -1, zWideFilename,
+                                nChar);
+  if( nChar==0 ){
+    sqlite3_free(zWideFilename);
+    zWideFilename = 0;
+  }
+  return zWideFilename;
+}
+#endif
+
+/*
+** The RBU handle is currently in RBU_STAGE_OAL state, with a SHARED lock
+** on the database file. This proc moves the *-oal file to the *-wal path,
+** then reopens the database file (this time in vanilla, non-oal, WAL mode).
+** If an error occurs, leave an error code and error message in the rbu 
+** handle.
+*/
+static void rbuMoveOalFile(sqlite3rbu *p){
+  const char *zBase = sqlite3_db_filename(p->dbMain, "main");
+  const char *zMove = zBase;
+  char *zOal;
+  char *zWal;
+
+  if( rbuIsVacuum(p) ){
+    zMove = sqlite3_db_filename(p->dbRbu, "main");
+  }
+  zOal = sqlite3_mprintf("%s-oal", zMove);
+  zWal = sqlite3_mprintf("%s-wal", zMove);
+
+  assert( p->eStage==RBU_STAGE_MOVE );
+  assert( p->rc==SQLITE_OK && p->zErrmsg==0 );
+  if( zWal==0 || zOal==0 ){
+    p->rc = SQLITE_NOMEM;
+  }else{
+    /* Move the *-oal file to *-wal. At this point connection p->db is
+    ** holding a SHARED lock on the target database file (because it is
+    ** in WAL mode). So no other connection may be writing the db. 
+    **
+    ** In order to ensure that there are no database readers, an EXCLUSIVE
+    ** lock is obtained here before the *-oal is moved to *-wal.
+    */
+    rbuLockDatabase(p);
+    if( p->rc==SQLITE_OK ){
+      rbuFileSuffix3(zBase, zWal);
+      rbuFileSuffix3(zBase, zOal);
+
+      /* Re-open the databases. */
+      rbuObjIterFinalize(&p->objiter);
+      sqlite3_close(p->dbRbu);
+      sqlite3_close(p->dbMain);
+      p->dbMain = 0;
+      p->dbRbu = 0;
+
+#if defined(_WIN32_WCE)
+      {
+        LPWSTR zWideOal;
+        LPWSTR zWideWal;
+
+        zWideOal = rbuWinUtf8ToUnicode(zOal);
+        if( zWideOal ){
+          zWideWal = rbuWinUtf8ToUnicode(zWal);
+          if( zWideWal ){
+            if( MoveFileW(zWideOal, zWideWal) ){
+              p->rc = SQLITE_OK;
+            }else{
+              p->rc = SQLITE_IOERR;
+            }
+            sqlite3_free(zWideWal);
+          }else{
+            p->rc = SQLITE_IOERR_NOMEM;
+          }
+          sqlite3_free(zWideOal);
+        }else{
+          p->rc = SQLITE_IOERR_NOMEM;
+        }
+      }
+#else
+      p->rc = rename(zOal, zWal) ? SQLITE_IOERR : SQLITE_OK;
+#endif
+
+      if( p->rc==SQLITE_OK ){
+        rbuOpenDatabase(p);
+        rbuSetupCheckpoint(p, 0);
+      }
+    }
+  }
+
+  sqlite3_free(zWal);
+  sqlite3_free(zOal);
+}
+
+/*
+** The SELECT statement iterating through the keys for the current object
+** (p->objiter.pSelect) currently points to a valid row. This function
+** determines the type of operation requested by this row and returns
+** one of the following values to indicate the result:
+**
+**     * RBU_INSERT
+**     * RBU_DELETE
+**     * RBU_IDX_DELETE
+**     * RBU_UPDATE
+**
+** If RBU_UPDATE is returned, then output variable *pzMask is set to
+** point to the text value indicating the columns to update.
+**
+** If the rbu_control field contains an invalid value, an error code and
+** message are left in the RBU handle and zero returned.
+*/
+static int rbuStepType(sqlite3rbu *p, const char **pzMask){
+  int iCol = p->objiter.nCol;     /* Index of rbu_control column */
+  int res = 0;                    /* Return value */
+
+  switch( sqlite3_column_type(p->objiter.pSelect, iCol) ){
+    case SQLITE_INTEGER: {
+      int iVal = sqlite3_column_int(p->objiter.pSelect, iCol);
+      switch( iVal ){
+        case 0: res = RBU_INSERT;     break;
+        case 1: res = RBU_DELETE;     break;
+        case 2: res = RBU_REPLACE;    break;
+        case 3: res = RBU_IDX_DELETE; break;
+        case 4: res = RBU_IDX_INSERT; break;
+      }
+      break;
+    }
+
+    case SQLITE_TEXT: {
+      const unsigned char *z = sqlite3_column_text(p->objiter.pSelect, iCol);
+      if( z==0 ){
+        p->rc = SQLITE_NOMEM;
+      }else{
+        *pzMask = (const char*)z;
+      }
+      res = RBU_UPDATE;
+
+      break;
+    }
+
+    default:
+      break;
+  }
+
+  if( res==0 ){
+    rbuBadControlError(p);
+  }
+  return res;
+}
+
+#ifdef SQLITE_DEBUG
+/*
+** Assert that column iCol of statement pStmt is named zName.
+*/
+static void assertColumnName(sqlite3_stmt *pStmt, int iCol, const char *zName){
+  const char *zCol = sqlite3_column_name(pStmt, iCol);
+  assert( 0==sqlite3_stricmp(zName, zCol) );
+}
+#else
+# define assertColumnName(x,y,z)
+#endif
+
+/*
+** Argument eType must be one of RBU_INSERT, RBU_DELETE, RBU_IDX_INSERT or
+** RBU_IDX_DELETE. This function performs the work of a single
+** sqlite3rbu_step() call for the type of operation specified by eType.
+*/
+static void rbuStepOneOp(sqlite3rbu *p, int eType){
+  RbuObjIter *pIter = &p->objiter;
+  sqlite3_value *pVal;
+  sqlite3_stmt *pWriter;
+  int i;
+
+  assert( p->rc==SQLITE_OK );
+  assert( eType!=RBU_DELETE || pIter->zIdx==0 );
+  assert( eType==RBU_DELETE || eType==RBU_IDX_DELETE
+       || eType==RBU_INSERT || eType==RBU_IDX_INSERT
+  );
+
+  /* If this is a delete, decrement nPhaseOneStep by nIndex. If the DELETE
+  ** statement below does actually delete a row, nPhaseOneStep will be
+  ** incremented by the same amount when SQL function rbu_tmp_insert()
+  ** is invoked by the trigger.  */
+  if( eType==RBU_DELETE ){
+    p->nPhaseOneStep -= p->objiter.nIndex;
+  }
+
+  if( eType==RBU_IDX_DELETE || eType==RBU_DELETE ){
+    pWriter = pIter->pDelete;
+  }else{
+    pWriter = pIter->pInsert;
+  }
+
+  for(i=0; i<pIter->nCol; i++){
+    /* If this is an INSERT into a table b-tree and the table has an
+    ** explicit INTEGER PRIMARY KEY, check that this is not an attempt
+    ** to write a NULL into the IPK column. That is not permitted.  */
+    if( eType==RBU_INSERT 
+     && pIter->zIdx==0 && pIter->eType==RBU_PK_IPK && pIter->abTblPk[i] 
+     && sqlite3_column_type(pIter->pSelect, i)==SQLITE_NULL
+    ){
+      p->rc = SQLITE_MISMATCH;
+      p->zErrmsg = sqlite3_mprintf("datatype mismatch");
+      return;
+    }
+
+    if( eType==RBU_DELETE && pIter->abTblPk[i]==0 ){
+      continue;
+    }
+
+    pVal = sqlite3_column_value(pIter->pSelect, i);
+    p->rc = sqlite3_bind_value(pWriter, i+1, pVal);
+    if( p->rc ) return;
+  }
+  if( pIter->zIdx==0 ){
+    if( pIter->eType==RBU_PK_VTAB 
+     || pIter->eType==RBU_PK_NONE 
+     || (pIter->eType==RBU_PK_EXTERNAL && rbuIsVacuum(p)) 
+    ){
+      /* For a virtual table, or a table with no primary key, the 
+      ** SELECT statement is:
+      **
+      **   SELECT <cols>, rbu_control, rbu_rowid FROM ....
+      **
+      ** Hence column_value(pIter->nCol+1).
+      */
+      assertColumnName(pIter->pSelect, pIter->nCol+1, 
+          rbuIsVacuum(p) ? "rowid" : "rbu_rowid"
+      );
+      pVal = sqlite3_column_value(pIter->pSelect, pIter->nCol+1);
+      p->rc = sqlite3_bind_value(pWriter, pIter->nCol+1, pVal);
+    }
+  }
+  if( p->rc==SQLITE_OK ){
+    sqlite3_step(pWriter);
+    p->rc = resetAndCollectError(pWriter, &p->zErrmsg);
+  }
+}
+
+/*
+** This function does the work for an sqlite3rbu_step() call.
+**
+** The object-iterator (p->objiter) currently points to a valid object,
+** and the input cursor (p->objiter.pSelect) currently points to a valid
+** input row. Perform whatever processing is required and return.
+**
+** If no  error occurs, SQLITE_OK is returned. Otherwise, an error code
+** and message is left in the RBU handle and a copy of the error code
+** returned.
+*/
+static int rbuStep(sqlite3rbu *p){
+  RbuObjIter *pIter = &p->objiter;
+  const char *zMask = 0;
+  int eType = rbuStepType(p, &zMask);
+
+  if( eType ){
+    assert( eType==RBU_INSERT     || eType==RBU_DELETE
+         || eType==RBU_REPLACE    || eType==RBU_IDX_DELETE
+         || eType==RBU_IDX_INSERT || eType==RBU_UPDATE
+    );
+    assert( eType!=RBU_UPDATE || pIter->zIdx==0 );
+
+    if( pIter->zIdx==0 && (eType==RBU_IDX_DELETE || eType==RBU_IDX_INSERT) ){
+      rbuBadControlError(p);
+    }
+    else if( eType==RBU_REPLACE ){
+      if( pIter->zIdx==0 ){
+        p->nPhaseOneStep += p->objiter.nIndex;
+        rbuStepOneOp(p, RBU_DELETE);
+      }
+      if( p->rc==SQLITE_OK ) rbuStepOneOp(p, RBU_INSERT);
+    }
+    else if( eType!=RBU_UPDATE ){
+      rbuStepOneOp(p, eType);
+    }
+    else{
+      sqlite3_value *pVal;
+      sqlite3_stmt *pUpdate = 0;
+      assert( eType==RBU_UPDATE );
+      p->nPhaseOneStep -= p->objiter.nIndex;
+      rbuGetUpdateStmt(p, pIter, zMask, &pUpdate);
+      if( pUpdate ){
+        int i;
+        for(i=0; p->rc==SQLITE_OK && i<pIter->nCol; i++){
+          char c = zMask[pIter->aiSrcOrder[i]];
+          pVal = sqlite3_column_value(pIter->pSelect, i);
+          if( pIter->abTblPk[i] || c!='.' ){
+            p->rc = sqlite3_bind_value(pUpdate, i+1, pVal);
+          }
+        }
+        if( p->rc==SQLITE_OK 
+         && (pIter->eType==RBU_PK_VTAB || pIter->eType==RBU_PK_NONE) 
+        ){
+          /* Bind the rbu_rowid value to column _rowid_ */
+          assertColumnName(pIter->pSelect, pIter->nCol+1, "rbu_rowid");
+          pVal = sqlite3_column_value(pIter->pSelect, pIter->nCol+1);
+          p->rc = sqlite3_bind_value(pUpdate, pIter->nCol+1, pVal);
+        }
+        if( p->rc==SQLITE_OK ){
+          sqlite3_step(pUpdate);
+          p->rc = resetAndCollectError(pUpdate, &p->zErrmsg);
+        }
+      }
+    }
+  }
+  return p->rc;
+}
+
+/*
+** Increment the schema cookie of the main database opened by p->dbMain.
+**
+** Or, if this is an RBU vacuum, set the schema cookie of the main db
+** opened by p->dbMain to one more than the schema cookie of the main
+** db opened by p->dbRbu.
+*/
+static void rbuIncrSchemaCookie(sqlite3rbu *p){
+  if( p->rc==SQLITE_OK ){
+    sqlite3 *dbread = (rbuIsVacuum(p) ? p->dbRbu : p->dbMain);
+    int iCookie = 1000000;
+    sqlite3_stmt *pStmt;
+
+    p->rc = prepareAndCollectError(dbread, &pStmt, &p->zErrmsg, 
+        "PRAGMA schema_version"
+    );
+    if( p->rc==SQLITE_OK ){
+      /* Coverage: it may be that this sqlite3_step() cannot fail. There
+      ** is already a transaction open, so the prepared statement cannot
+      ** throw an SQLITE_SCHEMA exception. The only database page the
+      ** statement reads is page 1, which is guaranteed to be in the cache.
+      ** And no memory allocations are required.  */
+      if( SQLITE_ROW==sqlite3_step(pStmt) ){
+        iCookie = sqlite3_column_int(pStmt, 0);
+      }
+      rbuFinalize(p, pStmt);
+    }
+    if( p->rc==SQLITE_OK ){
+      rbuMPrintfExec(p, p->dbMain, "PRAGMA schema_version = %d", iCookie+1);
+    }
+  }
+}
+
+/*
+** Update the contents of the rbu_state table within the rbu database. The
+** value stored in the RBU_STATE_STAGE column is eStage. All other values
+** are determined by inspecting the rbu handle passed as the first argument.
+*/
+static void rbuSaveState(sqlite3rbu *p, int eStage){
+  if( p->rc==SQLITE_OK || p->rc==SQLITE_DONE ){
+    sqlite3_stmt *pInsert = 0;
+    rbu_file *pFd = (rbuIsVacuum(p) ? p->pRbuFd : p->pTargetFd);
+    int rc;
+
+    assert( p->zErrmsg==0 );
+    rc = prepareFreeAndCollectError(p->dbRbu, &pInsert, &p->zErrmsg, 
+        sqlite3_mprintf(
+          "INSERT OR REPLACE INTO %s.rbu_state(k, v) VALUES "
+          "(%d, %d), "
+          "(%d, %Q), "
+          "(%d, %Q), "
+          "(%d, %d), "
+          "(%d, %d), "
+          "(%d, %lld), "
+          "(%d, %lld), "
+          "(%d, %lld), "
+          "(%d, %lld) ",
+          p->zStateDb,
+          RBU_STATE_STAGE, eStage,
+          RBU_STATE_TBL, p->objiter.zTbl, 
+          RBU_STATE_IDX, p->objiter.zIdx, 
+          RBU_STATE_ROW, p->nStep, 
+          RBU_STATE_PROGRESS, p->nProgress,
+          RBU_STATE_CKPT, p->iWalCksum,
+          RBU_STATE_COOKIE, (i64)pFd->iCookie,
+          RBU_STATE_OALSZ, p->iOalSz,
+          RBU_STATE_PHASEONESTEP, p->nPhaseOneStep
+      )
+    );
+    assert( pInsert==0 || rc==SQLITE_OK );
+
+    if( rc==SQLITE_OK ){
+      sqlite3_step(pInsert);
+      rc = sqlite3_finalize(pInsert);
+    }
+    if( rc!=SQLITE_OK ) p->rc = rc;
+  }
+}
+
+
+/*
+** The second argument passed to this function is the name of a PRAGMA 
+** setting - "page_size", "auto_vacuum", "user_version" or "application_id".
+** This function executes the following on sqlite3rbu.dbRbu:
+**
+**   "PRAGMA main.$zPragma"
+**
+** where $zPragma is the string passed as the second argument, then
+** on sqlite3rbu.dbMain:
+**
+**   "PRAGMA main.$zPragma = $val"
+**
+** where $val is the value returned by the first PRAGMA invocation.
+**
+** In short, it copies the value  of the specified PRAGMA setting from
+** dbRbu to dbMain.
+*/
+static void rbuCopyPragma(sqlite3rbu *p, const char *zPragma){
+  if( p->rc==SQLITE_OK ){
+    sqlite3_stmt *pPragma = 0;
+    p->rc = prepareFreeAndCollectError(p->dbRbu, &pPragma, &p->zErrmsg, 
+        sqlite3_mprintf("PRAGMA main.%s", zPragma)
+    );
+    if( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pPragma) ){
+      p->rc = rbuMPrintfExec(p, p->dbMain, "PRAGMA main.%s = %d",
+          zPragma, sqlite3_column_int(pPragma, 0)
+      );
+    }
+    rbuFinalize(p, pPragma);
+  }
+}
+
+/*
+** The RBU handle passed as the only argument has just been opened and 
+** the state database is empty. If this RBU handle was opened for an
+** RBU vacuum operation, create the schema in the target db.
+*/
+static void rbuCreateTargetSchema(sqlite3rbu *p){
+  sqlite3_stmt *pSql = 0;
+  sqlite3_stmt *pInsert = 0;
+
+  assert( rbuIsVacuum(p) );
+  p->rc = sqlite3_exec(p->dbMain, "PRAGMA writable_schema=1", 0,0, &p->zErrmsg);
+  if( p->rc==SQLITE_OK ){
+    p->rc = prepareAndCollectError(p->dbRbu, &pSql, &p->zErrmsg, 
+      "SELECT sql FROM sqlite_master WHERE sql!='' AND rootpage!=0"
+      " AND name!='sqlite_sequence' "
+      " ORDER BY type DESC"
+    );
+  }
+
+  while( p->rc==SQLITE_OK && sqlite3_step(pSql)==SQLITE_ROW ){
+    const char *zSql = (const char*)sqlite3_column_text(pSql, 0);
+    p->rc = sqlite3_exec(p->dbMain, zSql, 0, 0, &p->zErrmsg);
+  }
+  rbuFinalize(p, pSql);
+  if( p->rc!=SQLITE_OK ) return;
+
+  if( p->rc==SQLITE_OK ){
+    p->rc = prepareAndCollectError(p->dbRbu, &pSql, &p->zErrmsg, 
+        "SELECT * FROM sqlite_master WHERE rootpage=0 OR rootpage IS NULL" 
+    );
+  }
+
+  if( p->rc==SQLITE_OK ){
+    p->rc = prepareAndCollectError(p->dbMain, &pInsert, &p->zErrmsg, 
+        "INSERT INTO sqlite_master VALUES(?,?,?,?,?)"
+    );
+  }
+
+  while( p->rc==SQLITE_OK && sqlite3_step(pSql)==SQLITE_ROW ){
+    int i;
+    for(i=0; i<5; i++){
+      sqlite3_bind_value(pInsert, i+1, sqlite3_column_value(pSql, i));
+    }
+    sqlite3_step(pInsert);
+    p->rc = sqlite3_reset(pInsert);
+  }
+  if( p->rc==SQLITE_OK ){
+    p->rc = sqlite3_exec(p->dbMain, "PRAGMA writable_schema=0",0,0,&p->zErrmsg);
+  }
+
+  rbuFinalize(p, pSql);
+  rbuFinalize(p, pInsert);
+}
+
+/*
+** Step the RBU object.
+*/
+SQLITE_API int sqlite3rbu_step(sqlite3rbu *p){
+  if( p ){
+    switch( p->eStage ){
+      case RBU_STAGE_OAL: {
+        RbuObjIter *pIter = &p->objiter;
+
+        /* If this is an RBU vacuum operation and the state table was empty
+        ** when this handle was opened, create the target database schema. */
+        if( rbuIsVacuum(p) && p->nProgress==0 && p->rc==SQLITE_OK ){
+          rbuCreateTargetSchema(p);
+          rbuCopyPragma(p, "user_version");
+          rbuCopyPragma(p, "application_id");
+        }
+
+        while( p->rc==SQLITE_OK && pIter->zTbl ){
+
+          if( pIter->bCleanup ){
+            /* Clean up the rbu_tmp_xxx table for the previous table. It 
+            ** cannot be dropped as there are currently active SQL statements.
+            ** But the contents can be deleted.  */
+            if( rbuIsVacuum(p)==0 && pIter->abIndexed ){
+              rbuMPrintfExec(p, p->dbRbu, 
+                  "DELETE FROM %s.'rbu_tmp_%q'", p->zStateDb, pIter->zDataTbl
+              );
+            }
+          }else{
+            rbuObjIterPrepareAll(p, pIter, 0);
+
+            /* Advance to the next row to process. */
+            if( p->rc==SQLITE_OK ){
+              int rc = sqlite3_step(pIter->pSelect);
+              if( rc==SQLITE_ROW ){
+                p->nProgress++;
+                p->nStep++;
+                return rbuStep(p);
+              }
+              p->rc = sqlite3_reset(pIter->pSelect);
+              p->nStep = 0;
+            }
+          }
+
+          rbuObjIterNext(p, pIter);
+        }
+
+        if( p->rc==SQLITE_OK ){
+          assert( pIter->zTbl==0 );
+          rbuSaveState(p, RBU_STAGE_MOVE);
+          rbuIncrSchemaCookie(p);
+          if( p->rc==SQLITE_OK ){
+            p->rc = sqlite3_exec(p->dbMain, "COMMIT", 0, 0, &p->zErrmsg);
+          }
+          if( p->rc==SQLITE_OK ){
+            p->rc = sqlite3_exec(p->dbRbu, "COMMIT", 0, 0, &p->zErrmsg);
+          }
+          p->eStage = RBU_STAGE_MOVE;
+        }
+        break;
+      }
+
+      case RBU_STAGE_MOVE: {
+        if( p->rc==SQLITE_OK ){
+          rbuMoveOalFile(p);
+          p->nProgress++;
+        }
+        break;
+      }
+
+      case RBU_STAGE_CKPT: {
+        if( p->rc==SQLITE_OK ){
+          if( p->nStep>=p->nFrame ){
+            sqlite3_file *pDb = p->pTargetFd->pReal;
+  
+            /* Sync the db file */
+            p->rc = pDb->pMethods->xSync(pDb, SQLITE_SYNC_NORMAL);
+  
+            /* Update nBackfill */
+            if( p->rc==SQLITE_OK ){
+              void volatile *ptr;
+              p->rc = pDb->pMethods->xShmMap(pDb, 0, 32*1024, 0, &ptr);
+              if( p->rc==SQLITE_OK ){
+                ((u32 volatile*)ptr)[24] = p->iMaxFrame;
+              }
+            }
+  
+            if( p->rc==SQLITE_OK ){
+              p->eStage = RBU_STAGE_DONE;
+              p->rc = SQLITE_DONE;
+            }
+          }else{
+            RbuFrame *pFrame = &p->aFrame[p->nStep];
+            rbuCheckpointFrame(p, pFrame);
+            p->nStep++;
+          }
+          p->nProgress++;
+        }
+        break;
+      }
+
+      default:
+        break;
+    }
+    return p->rc;
+  }else{
+    return SQLITE_NOMEM;
+  }
+}
+
+/*
+** Compare strings z1 and z2, returning 0 if they are identical, or non-zero
+** otherwise. Either or both argument may be NULL. Two NULL values are
+** considered equal, and NULL is considered distinct from all other values.
+*/
+static int rbuStrCompare(const char *z1, const char *z2){
+  if( z1==0 && z2==0 ) return 0;
+  if( z1==0 || z2==0 ) return 1;
+  return (sqlite3_stricmp(z1, z2)!=0);
+}
+
+/*
+** This function is called as part of sqlite3rbu_open() when initializing
+** an rbu handle in OAL stage. If the rbu update has not started (i.e.
+** the rbu_state table was empty) it is a no-op. Otherwise, it arranges
+** things so that the next call to sqlite3rbu_step() continues on from
+** where the previous rbu handle left off.
+**
+** If an error occurs, an error code and error message are left in the
+** rbu handle passed as the first argument.
+*/
+static void rbuSetupOal(sqlite3rbu *p, RbuState *pState){
+  assert( p->rc==SQLITE_OK );
+  if( pState->zTbl ){
+    RbuObjIter *pIter = &p->objiter;
+    int rc = SQLITE_OK;
+
+    while( rc==SQLITE_OK && pIter->zTbl && (pIter->bCleanup 
+       || rbuStrCompare(pIter->zIdx, pState->zIdx)
+       || rbuStrCompare(pIter->zTbl, pState->zTbl) 
+    )){
+      rc = rbuObjIterNext(p, pIter);
+    }
+
+    if( rc==SQLITE_OK && !pIter->zTbl ){
+      rc = SQLITE_ERROR;
+      p->zErrmsg = sqlite3_mprintf("rbu_state mismatch error");
+    }
+
+    if( rc==SQLITE_OK ){
+      p->nStep = pState->nRow;
+      rc = rbuObjIterPrepareAll(p, &p->objiter, p->nStep);
+    }
+
+    p->rc = rc;
+  }
+}
+
+/*
+** If there is a "*-oal" file in the file-system corresponding to the
+** target database in the file-system, delete it. If an error occurs,
+** leave an error code and error message in the rbu handle.
+*/
+static void rbuDeleteOalFile(sqlite3rbu *p){
+  char *zOal = rbuMPrintf(p, "%s-oal", p->zTarget);
+  if( zOal ){
+    sqlite3_vfs *pVfs = sqlite3_vfs_find(0);
+    assert( pVfs && p->rc==SQLITE_OK && p->zErrmsg==0 );
+    pVfs->xDelete(pVfs, zOal, 0);
+    sqlite3_free(zOal);
+  }
+}
+
+/*
+** Allocate a private rbu VFS for the rbu handle passed as the only
+** argument. This VFS will be used unless the call to sqlite3rbu_open()
+** specified a URI with a vfs=? option in place of a target database
+** file name.
+*/
+static void rbuCreateVfs(sqlite3rbu *p){
+  int rnd;
+  char zRnd[64];
+
+  assert( p->rc==SQLITE_OK );
+  sqlite3_randomness(sizeof(int), (void*)&rnd);
+  sqlite3_snprintf(sizeof(zRnd), zRnd, "rbu_vfs_%d", rnd);
+  p->rc = sqlite3rbu_create_vfs(zRnd, 0);
+  if( p->rc==SQLITE_OK ){
+    sqlite3_vfs *pVfs = sqlite3_vfs_find(zRnd);
+    assert( pVfs );
+    p->zVfsName = pVfs->zName;
+  }
+}
+
+/*
+** Destroy the private VFS created for the rbu handle passed as the only
+** argument by an earlier call to rbuCreateVfs().
+*/
+static void rbuDeleteVfs(sqlite3rbu *p){
+  if( p->zVfsName ){
+    sqlite3rbu_destroy_vfs(p->zVfsName);
+    p->zVfsName = 0;
+  }
+}
+
+/*
+** This user-defined SQL function is invoked with a single argument - the
+** name of a table expected to appear in the target database. It returns
+** the number of auxilliary indexes on the table.
+*/
+static void rbuIndexCntFunc(
+  sqlite3_context *pCtx, 
+  int nVal,
+  sqlite3_value **apVal
+){
+  sqlite3rbu *p = (sqlite3rbu*)sqlite3_user_data(pCtx);
+  sqlite3_stmt *pStmt = 0;
+  char *zErrmsg = 0;
+  int rc;
+
+  assert( nVal==1 );
+  
+  rc = prepareFreeAndCollectError(p->dbMain, &pStmt, &zErrmsg, 
+      sqlite3_mprintf("SELECT count(*) FROM sqlite_master "
+        "WHERE type='index' AND tbl_name = %Q", sqlite3_value_text(apVal[0]))
+  );
+  if( rc!=SQLITE_OK ){
+    sqlite3_result_error(pCtx, zErrmsg, -1);
+  }else{
+    int nIndex = 0;
+    if( SQLITE_ROW==sqlite3_step(pStmt) ){
+      nIndex = sqlite3_column_int(pStmt, 0);
+    }
+    rc = sqlite3_finalize(pStmt);
+    if( rc==SQLITE_OK ){
+      sqlite3_result_int(pCtx, nIndex);
+    }else{
+      sqlite3_result_error(pCtx, sqlite3_errmsg(p->dbMain), -1);
+    }
+  }
+
+  sqlite3_free(zErrmsg);
+}
+
+/*
+** If the RBU database contains the rbu_count table, use it to initialize
+** the sqlite3rbu.nPhaseOneStep variable. The schema of the rbu_count table
+** is assumed to contain the same columns as:
+**
+**   CREATE TABLE rbu_count(tbl TEXT PRIMARY KEY, cnt INTEGER) WITHOUT ROWID;
+**
+** There should be one row in the table for each data_xxx table in the
+** database. The 'tbl' column should contain the name of a data_xxx table,
+** and the cnt column the number of rows it contains.
+**
+** sqlite3rbu.nPhaseOneStep is initialized to the sum of (1 + nIndex) * cnt
+** for all rows in the rbu_count table, where nIndex is the number of 
+** indexes on the corresponding target database table.
+*/
+static void rbuInitPhaseOneSteps(sqlite3rbu *p){
+  if( p->rc==SQLITE_OK ){
+    sqlite3_stmt *pStmt = 0;
+    int bExists = 0;                /* True if rbu_count exists */
+
+    p->nPhaseOneStep = -1;
+
+    p->rc = sqlite3_create_function(p->dbRbu, 
+        "rbu_index_cnt", 1, SQLITE_UTF8, (void*)p, rbuIndexCntFunc, 0, 0
+    );
+  
+    /* Check for the rbu_count table. If it does not exist, or if an error
+    ** occurs, nPhaseOneStep will be left set to -1. */
+    if( p->rc==SQLITE_OK ){
+      p->rc = prepareAndCollectError(p->dbRbu, &pStmt, &p->zErrmsg,
+          "SELECT 1 FROM sqlite_master WHERE tbl_name = 'rbu_count'"
+      );
+    }
+    if( p->rc==SQLITE_OK ){
+      if( SQLITE_ROW==sqlite3_step(pStmt) ){
+        bExists = 1;
+      }
+      p->rc = sqlite3_finalize(pStmt);
+    }
+  
+    if( p->rc==SQLITE_OK && bExists ){
+      p->rc = prepareAndCollectError(p->dbRbu, &pStmt, &p->zErrmsg,
+          "SELECT sum(cnt * (1 + rbu_index_cnt(rbu_target_name(tbl))))"
+          "FROM rbu_count"
+      );
+      if( p->rc==SQLITE_OK ){
+        if( SQLITE_ROW==sqlite3_step(pStmt) ){
+          p->nPhaseOneStep = sqlite3_column_int64(pStmt, 0);
+        }
+        p->rc = sqlite3_finalize(pStmt);
+      }
+    }
+  }
+}
+
+
+static sqlite3rbu *openRbuHandle(
+  const char *zTarget, 
+  const char *zRbu,
+  const char *zState
+){
+  sqlite3rbu *p;
+  size_t nTarget = zTarget ? strlen(zTarget) : 0;
+  size_t nRbu = strlen(zRbu);
+  size_t nByte = sizeof(sqlite3rbu) + nTarget+1 + nRbu+1;
+
+  p = (sqlite3rbu*)sqlite3_malloc64(nByte);
+  if( p ){
+    RbuState *pState = 0;
+
+    /* Create the custom VFS. */
+    memset(p, 0, sizeof(sqlite3rbu));
+    rbuCreateVfs(p);
+
+    /* Open the target, RBU and state databases */
+    if( p->rc==SQLITE_OK ){
+      char *pCsr = (char*)&p[1];
+      if( zTarget ){
+        p->zTarget = pCsr;
+        memcpy(p->zTarget, zTarget, nTarget+1);
+        pCsr += nTarget+1;
+      }
+      p->zRbu = pCsr;
+      memcpy(p->zRbu, zRbu, nRbu+1);
+      pCsr += nRbu+1;
+      if( zState ){
+        p->zState = rbuMPrintf(p, "%s", zState);
+      }
+      rbuOpenDatabase(p);
+    }
+
+    if( p->rc==SQLITE_OK ){
+      pState = rbuLoadState(p);
+      assert( pState || p->rc!=SQLITE_OK );
+      if( p->rc==SQLITE_OK ){
+
+        if( pState->eStage==0 ){ 
+          rbuDeleteOalFile(p);
+          rbuInitPhaseOneSteps(p);
+          p->eStage = RBU_STAGE_OAL;
+        }else{
+          p->eStage = pState->eStage;
+          p->nPhaseOneStep = pState->nPhaseOneStep;
+        }
+        p->nProgress = pState->nProgress;
+        p->iOalSz = pState->iOalSz;
+      }
+    }
+    assert( p->rc!=SQLITE_OK || p->eStage!=0 );
+
+    if( p->rc==SQLITE_OK && p->pTargetFd->pWalFd ){
+      if( p->eStage==RBU_STAGE_OAL ){
+        p->rc = SQLITE_ERROR;
+        p->zErrmsg = sqlite3_mprintf("cannot update wal mode database");
+      }else if( p->eStage==RBU_STAGE_MOVE ){
+        p->eStage = RBU_STAGE_CKPT;
+        p->nStep = 0;
+      }
+    }
+
+    if( p->rc==SQLITE_OK 
+     && (p->eStage==RBU_STAGE_OAL || p->eStage==RBU_STAGE_MOVE)
+     && pState->eStage!=0
+    ){
+      rbu_file *pFd = (rbuIsVacuum(p) ? p->pRbuFd : p->pTargetFd);
+      if( pFd->iCookie!=pState->iCookie ){   
+        /* At this point (pTargetFd->iCookie) contains the value of the
+        ** change-counter cookie (the thing that gets incremented when a 
+        ** transaction is committed in rollback mode) currently stored on 
+        ** page 1 of the database file. */
+        p->rc = SQLITE_BUSY;
+        p->zErrmsg = sqlite3_mprintf("database modified during rbu %s",
+            (rbuIsVacuum(p) ? "vacuum" : "update")
+        );
+      }
+    }
+
+    if( p->rc==SQLITE_OK ){
+      if( p->eStage==RBU_STAGE_OAL ){
+        sqlite3 *db = p->dbMain;
+        p->rc = sqlite3_exec(p->dbRbu, "BEGIN", 0, 0, &p->zErrmsg);
+
+        /* Point the object iterator at the first object */
+        if( p->rc==SQLITE_OK ){
+          p->rc = rbuObjIterFirst(p, &p->objiter);
+        }
+
+        /* If the RBU database contains no data_xxx tables, declare the RBU
+        ** update finished.  */
+        if( p->rc==SQLITE_OK && p->objiter.zTbl==0 ){
+          p->rc = SQLITE_DONE;
+          p->eStage = RBU_STAGE_DONE;
+        }else{
+          if( p->rc==SQLITE_OK && pState->eStage==0 && rbuIsVacuum(p) ){
+            rbuCopyPragma(p, "page_size");
+            rbuCopyPragma(p, "auto_vacuum");
+          }
+
+          /* Open transactions both databases. The *-oal file is opened or
+          ** created at this point. */
+          if( p->rc==SQLITE_OK ){
+            p->rc = sqlite3_exec(db, "BEGIN IMMEDIATE", 0, 0, &p->zErrmsg);
+          }
+
+          /* Check if the main database is a zipvfs db. If it is, set the upper
+          ** level pager to use "journal_mode=off". This prevents it from 
+          ** generating a large journal using a temp file.  */
+          if( p->rc==SQLITE_OK ){
+            int frc = sqlite3_file_control(db, "main", SQLITE_FCNTL_ZIPVFS, 0);
+            if( frc==SQLITE_OK ){
+              p->rc = sqlite3_exec(
+                db, "PRAGMA journal_mode=off",0,0,&p->zErrmsg);
+            }
+          }
+
+          if( p->rc==SQLITE_OK ){
+            rbuSetupOal(p, pState);
+          }
+        }
+      }else if( p->eStage==RBU_STAGE_MOVE ){
+        /* no-op */
+      }else if( p->eStage==RBU_STAGE_CKPT ){
+        rbuSetupCheckpoint(p, pState);
+      }else if( p->eStage==RBU_STAGE_DONE ){
+        p->rc = SQLITE_DONE;
+      }else{
+        p->rc = SQLITE_CORRUPT;
+      }
+    }
+
+    rbuFreeState(pState);
+  }
+
+  return p;
+}
+
+/*
+** Allocate and return an RBU handle with all fields zeroed except for the
+** error code, which is set to SQLITE_MISUSE.
+*/
+static sqlite3rbu *rbuMisuseError(void){
+  sqlite3rbu *pRet;
+  pRet = sqlite3_malloc64(sizeof(sqlite3rbu));
+  if( pRet ){
+    memset(pRet, 0, sizeof(sqlite3rbu));
+    pRet->rc = SQLITE_MISUSE;
+  }
+  return pRet;
+}
+
+/*
+** Open and return a new RBU handle. 
+*/
+SQLITE_API sqlite3rbu *sqlite3rbu_open(
+  const char *zTarget, 
+  const char *zRbu,
+  const char *zState
+){
+  if( zTarget==0 || zRbu==0 ){ return rbuMisuseError(); }
+  /* TODO: Check that zTarget and zRbu are non-NULL */
+  return openRbuHandle(zTarget, zRbu, zState);
+}
+
+/*
+** Open a handle to begin or resume an RBU VACUUM operation.
+*/
+SQLITE_API sqlite3rbu *sqlite3rbu_vacuum(
+  const char *zTarget, 
+  const char *zState
+){
+  if( zTarget==0 ){ return rbuMisuseError(); }
+  /* TODO: Check that both arguments are non-NULL */
+  return openRbuHandle(0, zTarget, zState);
+}
+
+/*
+** Return the database handle used by pRbu.
+*/
+SQLITE_API sqlite3 *sqlite3rbu_db(sqlite3rbu *pRbu, int bRbu){
+  sqlite3 *db = 0;
+  if( pRbu ){
+    db = (bRbu ? pRbu->dbRbu : pRbu->dbMain);
+  }
+  return db;
+}
+
+
+/*
+** If the error code currently stored in the RBU handle is SQLITE_CONSTRAINT,
+** then edit any error message string so as to remove all occurrences of
+** the pattern "rbu_imp_[0-9]*".
+*/
+static void rbuEditErrmsg(sqlite3rbu *p){
+  if( p->rc==SQLITE_CONSTRAINT && p->zErrmsg ){
+    unsigned int i;
+    size_t nErrmsg = strlen(p->zErrmsg);
+    for(i=0; i<(nErrmsg-8); i++){
+      if( memcmp(&p->zErrmsg[i], "rbu_imp_", 8)==0 ){
+        int nDel = 8;
+        while( p->zErrmsg[i+nDel]>='0' && p->zErrmsg[i+nDel]<='9' ) nDel++;
+        memmove(&p->zErrmsg[i], &p->zErrmsg[i+nDel], nErrmsg + 1 - i - nDel);
+        nErrmsg -= nDel;
+      }
+    }
+  }
+}
+
+/*
+** Close the RBU handle.
+*/
+SQLITE_API int sqlite3rbu_close(sqlite3rbu *p, char **pzErrmsg){
+  int rc;
+  if( p ){
+
+    /* Commit the transaction to the *-oal file. */
+    if( p->rc==SQLITE_OK && p->eStage==RBU_STAGE_OAL ){
+      p->rc = sqlite3_exec(p->dbMain, "COMMIT", 0, 0, &p->zErrmsg);
+    }
+
+    rbuSaveState(p, p->eStage);
+
+    if( p->rc==SQLITE_OK && p->eStage==RBU_STAGE_OAL ){
+      p->rc = sqlite3_exec(p->dbRbu, "COMMIT", 0, 0, &p->zErrmsg);
+    }
+
+    /* Close any open statement handles. */
+    rbuObjIterFinalize(&p->objiter);
+
+    /* If this is an RBU vacuum handle and the vacuum has either finished
+    ** successfully or encountered an error, delete the contents of the 
+    ** state table. This causes the next call to sqlite3rbu_vacuum() 
+    ** specifying the current target and state databases to start a new
+    ** vacuum from scratch.  */
+    if( rbuIsVacuum(p) && p->rc!=SQLITE_OK && p->dbRbu ){
+      int rc2 = sqlite3_exec(p->dbRbu, "DELETE FROM stat.rbu_state", 0, 0, 0);
+      if( p->rc==SQLITE_DONE && rc2!=SQLITE_OK ) p->rc = rc2;
+    }
+
+    /* Close the open database handle and VFS object. */
+    sqlite3_close(p->dbRbu);
+    sqlite3_close(p->dbMain);
+    rbuDeleteVfs(p);
+    sqlite3_free(p->aBuf);
+    sqlite3_free(p->aFrame);
+
+    rbuEditErrmsg(p);
+    rc = p->rc;
+    *pzErrmsg = p->zErrmsg;
+    sqlite3_free(p->zState);
+    sqlite3_free(p);
+  }else{
+    rc = SQLITE_NOMEM;
+    *pzErrmsg = 0;
+  }
+  return rc;
+}
+
+/*
+** Return the total number of key-value operations (inserts, deletes or 
+** updates) that have been performed on the target database since the
+** current RBU update was started.
+*/
+SQLITE_API sqlite3_int64 sqlite3rbu_progress(sqlite3rbu *pRbu){
+  return pRbu->nProgress;
+}
+
+/*
+** Return permyriadage progress indications for the two main stages of
+** an RBU update.
+*/
+SQLITE_API void sqlite3rbu_bp_progress(sqlite3rbu *p, int *pnOne, int *pnTwo){
+  const int MAX_PROGRESS = 10000;
+  switch( p->eStage ){
+    case RBU_STAGE_OAL:
+      if( p->nPhaseOneStep>0 ){
+        *pnOne = (int)(MAX_PROGRESS * (i64)p->nProgress/(i64)p->nPhaseOneStep);
+      }else{
+        *pnOne = -1;
+      }
+      *pnTwo = 0;
+      break;
+
+    case RBU_STAGE_MOVE:
+      *pnOne = MAX_PROGRESS;
+      *pnTwo = 0;
+      break;
+
+    case RBU_STAGE_CKPT:
+      *pnOne = MAX_PROGRESS;
+      *pnTwo = (int)(MAX_PROGRESS * (i64)p->nStep / (i64)p->nFrame);
+      break;
+
+    case RBU_STAGE_DONE:
+      *pnOne = MAX_PROGRESS;
+      *pnTwo = MAX_PROGRESS;
+      break;
+
+    default:
+      assert( 0 );
+  }
+}
+
+/*
+** Return the current state of the RBU vacuum or update operation.
+*/
+SQLITE_API int sqlite3rbu_state(sqlite3rbu *p){
+  int aRes[] = {
+    0, SQLITE_RBU_STATE_OAL, SQLITE_RBU_STATE_MOVE,
+    0, SQLITE_RBU_STATE_CHECKPOINT, SQLITE_RBU_STATE_DONE
+  };
+
+  assert( RBU_STAGE_OAL==1 );
+  assert( RBU_STAGE_MOVE==2 );
+  assert( RBU_STAGE_CKPT==4 );
+  assert( RBU_STAGE_DONE==5 );
+  assert( aRes[RBU_STAGE_OAL]==SQLITE_RBU_STATE_OAL );
+  assert( aRes[RBU_STAGE_MOVE]==SQLITE_RBU_STATE_MOVE );
+  assert( aRes[RBU_STAGE_CKPT]==SQLITE_RBU_STATE_CHECKPOINT );
+  assert( aRes[RBU_STAGE_DONE]==SQLITE_RBU_STATE_DONE );
+
+  if( p->rc!=SQLITE_OK && p->rc!=SQLITE_DONE ){
+    return SQLITE_RBU_STATE_ERROR;
+  }else{
+    assert( p->rc!=SQLITE_DONE || p->eStage==RBU_STAGE_DONE );
+    assert( p->eStage==RBU_STAGE_OAL
+         || p->eStage==RBU_STAGE_MOVE
+         || p->eStage==RBU_STAGE_CKPT
+         || p->eStage==RBU_STAGE_DONE
+    );
+    return aRes[p->eStage];
+  }
+}
+
+SQLITE_API int sqlite3rbu_savestate(sqlite3rbu *p){
+  int rc = p->rc;
+  if( rc==SQLITE_DONE ) return SQLITE_OK;
+
+  assert( p->eStage>=RBU_STAGE_OAL && p->eStage<=RBU_STAGE_DONE );
+  if( p->eStage==RBU_STAGE_OAL ){
+    assert( rc!=SQLITE_DONE );
+    if( rc==SQLITE_OK ) rc = sqlite3_exec(p->dbMain, "COMMIT", 0, 0, 0);
+  }
+
+  p->rc = rc;
+  rbuSaveState(p, p->eStage);
+  rc = p->rc;
+
+  if( p->eStage==RBU_STAGE_OAL ){
+    assert( rc!=SQLITE_DONE );
+    if( rc==SQLITE_OK ) rc = sqlite3_exec(p->dbRbu, "COMMIT", 0, 0, 0);
+    if( rc==SQLITE_OK ) rc = sqlite3_exec(p->dbRbu, "BEGIN IMMEDIATE", 0, 0, 0);
+    if( rc==SQLITE_OK ) rc = sqlite3_exec(p->dbMain, "BEGIN IMMEDIATE", 0, 0,0);
+  }
+
+  p->rc = rc;
+  return rc;
+}
+
+/**************************************************************************
+** Beginning of RBU VFS shim methods. The VFS shim modifies the behaviour
+** of a standard VFS in the following ways:
+**
+** 1. Whenever the first page of a main database file is read or 
+**    written, the value of the change-counter cookie is stored in
+**    rbu_file.iCookie. Similarly, the value of the "write-version"
+**    database header field is stored in rbu_file.iWriteVer. This ensures
+**    that the values are always trustworthy within an open transaction.
+**
+** 2. Whenever an SQLITE_OPEN_WAL file is opened, the (rbu_file.pWalFd)
+**    member variable of the associated database file descriptor is set
+**    to point to the new file. A mutex protected linked list of all main 
+**    db fds opened using a particular RBU VFS is maintained at 
+**    rbu_vfs.pMain to facilitate this.
+**
+** 3. Using a new file-control "SQLITE_FCNTL_RBU", a main db rbu_file 
+**    object can be marked as the target database of an RBU update. This
+**    turns on the following extra special behaviour:
+**
+** 3a. If xAccess() is called to check if there exists a *-wal file 
+**     associated with an RBU target database currently in RBU_STAGE_OAL
+**     stage (preparing the *-oal file), the following special handling
+**     applies:
+**
+**      * if the *-wal file does exist, return SQLITE_CANTOPEN. An RBU
+**        target database may not be in wal mode already.
+**
+**      * if the *-wal file does not exist, set the output parameter to
+**        non-zero (to tell SQLite that it does exist) anyway.
+**
+**     Then, when xOpen() is called to open the *-wal file associated with
+**     the RBU target in RBU_STAGE_OAL stage, instead of opening the *-wal
+**     file, the rbu vfs opens the corresponding *-oal file instead. 
+**
+** 3b. The *-shm pages returned by xShmMap() for a target db file in
+**     RBU_STAGE_OAL mode are actually stored in heap memory. This is to
+**     avoid creating a *-shm file on disk. Additionally, xShmLock() calls
+**     are no-ops on target database files in RBU_STAGE_OAL mode. This is
+**     because assert() statements in some VFS implementations fail if 
+**     xShmLock() is called before xShmMap().
+**
+** 3c. If an EXCLUSIVE lock is attempted on a target database file in any
+**     mode except RBU_STAGE_DONE (all work completed and checkpointed), it 
+**     fails with an SQLITE_BUSY error. This is to stop RBU connections
+**     from automatically checkpointing a *-wal (or *-oal) file from within
+**     sqlite3_close().
+**
+** 3d. In RBU_STAGE_CAPTURE mode, all xRead() calls on the wal file, and
+**     all xWrite() calls on the target database file perform no IO. 
+**     Instead the frame and page numbers that would be read and written
+**     are recorded. Additionally, successful attempts to obtain exclusive
+**     xShmLock() WRITER, CHECKPOINTER and READ0 locks on the target 
+**     database file are recorded. xShmLock() calls to unlock the same
+**     locks are no-ops (so that once obtained, these locks are never
+**     relinquished). Finally, calls to xSync() on the target database
+**     file fail with SQLITE_INTERNAL errors.
+*/
+
+static void rbuUnlockShm(rbu_file *p){
+  if( p->pRbu ){
+    int (*xShmLock)(sqlite3_file*,int,int,int) = p->pReal->pMethods->xShmLock;
+    int i;
+    for(i=0; i<SQLITE_SHM_NLOCK;i++){
+      if( (1<<i) & p->pRbu->mLock ){
+        xShmLock(p->pReal, i, 1, SQLITE_SHM_UNLOCK|SQLITE_SHM_EXCLUSIVE);
+      }
+    }
+    p->pRbu->mLock = 0;
+  }
+}
+
+/*
+** Close an rbu file.
+*/
+static int rbuVfsClose(sqlite3_file *pFile){
+  rbu_file *p = (rbu_file*)pFile;
+  int rc;
+  int i;
+
+  /* Free the contents of the apShm[] array. And the array itself. */
+  for(i=0; i<p->nShm; i++){
+    sqlite3_free(p->apShm[i]);
+  }
+  sqlite3_free(p->apShm);
+  p->apShm = 0;
+  sqlite3_free(p->zDel);
+
+  if( p->openFlags & SQLITE_OPEN_MAIN_DB ){
+    rbu_file **pp;
+    sqlite3_mutex_enter(p->pRbuVfs->mutex);
+    for(pp=&p->pRbuVfs->pMain; *pp!=p; pp=&((*pp)->pMainNext));
+    *pp = p->pMainNext;
+    sqlite3_mutex_leave(p->pRbuVfs->mutex);
+    rbuUnlockShm(p);
+    p->pReal->pMethods->xShmUnmap(p->pReal, 0);
+  }
+
+  /* Close the underlying file handle */
+  rc = p->pReal->pMethods->xClose(p->pReal);
+  return rc;
+}
+
+
+/*
+** Read and return an unsigned 32-bit big-endian integer from the buffer 
+** passed as the only argument.
+*/
+static u32 rbuGetU32(u8 *aBuf){
+  return ((u32)aBuf[0] << 24)
+       + ((u32)aBuf[1] << 16)
+       + ((u32)aBuf[2] <<  8)
+       + ((u32)aBuf[3]);
+}
+
+/*
+** Write an unsigned 32-bit value in big-endian format to the supplied
+** buffer.
+*/
+static void rbuPutU32(u8 *aBuf, u32 iVal){
+  aBuf[0] = (iVal >> 24) & 0xFF;
+  aBuf[1] = (iVal >> 16) & 0xFF;
+  aBuf[2] = (iVal >>  8) & 0xFF;
+  aBuf[3] = (iVal >>  0) & 0xFF;
+}
+
+static void rbuPutU16(u8 *aBuf, u16 iVal){
+  aBuf[0] = (iVal >>  8) & 0xFF;
+  aBuf[1] = (iVal >>  0) & 0xFF;
+}
+
+/*
+** Read data from an rbuVfs-file.
+*/
+static int rbuVfsRead(
+  sqlite3_file *pFile, 
+  void *zBuf, 
+  int iAmt, 
+  sqlite_int64 iOfst
+){
+  rbu_file *p = (rbu_file*)pFile;
+  sqlite3rbu *pRbu = p->pRbu;
+  int rc;
+
+  if( pRbu && pRbu->eStage==RBU_STAGE_CAPTURE ){
+    assert( p->openFlags & SQLITE_OPEN_WAL );
+    rc = rbuCaptureWalRead(p->pRbu, iOfst, iAmt);
+  }else{
+    if( pRbu && pRbu->eStage==RBU_STAGE_OAL 
+     && (p->openFlags & SQLITE_OPEN_WAL) 
+     && iOfst>=pRbu->iOalSz 
+    ){
+      rc = SQLITE_OK;
+      memset(zBuf, 0, iAmt);
+    }else{
+      rc = p->pReal->pMethods->xRead(p->pReal, zBuf, iAmt, iOfst);
+#if 1
+      /* If this is being called to read the first page of the target 
+      ** database as part of an rbu vacuum operation, synthesize the 
+      ** contents of the first page if it does not yet exist. Otherwise,
+      ** SQLite will not check for a *-wal file.  */
+      if( pRbu && rbuIsVacuum(pRbu) 
+          && rc==SQLITE_IOERR_SHORT_READ && iOfst==0
+          && (p->openFlags & SQLITE_OPEN_MAIN_DB)
+          && pRbu->rc==SQLITE_OK
+      ){
+        sqlite3_file *pFd = (sqlite3_file*)pRbu->pRbuFd;
+        rc = pFd->pMethods->xRead(pFd, zBuf, iAmt, iOfst);
+        if( rc==SQLITE_OK ){
+          u8 *aBuf = (u8*)zBuf;
+          u32 iRoot = rbuGetU32(&aBuf[52]) ? 1 : 0;
+          rbuPutU32(&aBuf[52], iRoot);      /* largest root page number */
+          rbuPutU32(&aBuf[36], 0);          /* number of free pages */
+          rbuPutU32(&aBuf[32], 0);          /* first page on free list trunk */
+          rbuPutU32(&aBuf[28], 1);          /* size of db file in pages */
+          rbuPutU32(&aBuf[24], pRbu->pRbuFd->iCookie+1);  /* Change counter */
+
+          if( iAmt>100 ){
+            memset(&aBuf[100], 0, iAmt-100);
+            rbuPutU16(&aBuf[105], iAmt & 0xFFFF);
+            aBuf[100] = 0x0D;
+          }
+        }
+      }
+#endif
+    }
+    if( rc==SQLITE_OK && iOfst==0 && (p->openFlags & SQLITE_OPEN_MAIN_DB) ){
+      /* These look like magic numbers. But they are stable, as they are part
+       ** of the definition of the SQLite file format, which may not change. */
+      u8 *pBuf = (u8*)zBuf;
+      p->iCookie = rbuGetU32(&pBuf[24]);
+      p->iWriteVer = pBuf[19];
+    }
+  }
+  return rc;
+}
+
+/*
+** Write data to an rbuVfs-file.
+*/
+static int rbuVfsWrite(
+  sqlite3_file *pFile, 
+  const void *zBuf, 
+  int iAmt, 
+  sqlite_int64 iOfst
+){
+  rbu_file *p = (rbu_file*)pFile;
+  sqlite3rbu *pRbu = p->pRbu;
+  int rc;
+
+  if( pRbu && pRbu->eStage==RBU_STAGE_CAPTURE ){
+    assert( p->openFlags & SQLITE_OPEN_MAIN_DB );
+    rc = rbuCaptureDbWrite(p->pRbu, iOfst);
+  }else{
+    if( pRbu && pRbu->eStage==RBU_STAGE_OAL 
+     && (p->openFlags & SQLITE_OPEN_WAL) 
+     && iOfst>=pRbu->iOalSz
+    ){
+      pRbu->iOalSz = iAmt + iOfst;
+    }
+    rc = p->pReal->pMethods->xWrite(p->pReal, zBuf, iAmt, iOfst);
+    if( rc==SQLITE_OK && iOfst==0 && (p->openFlags & SQLITE_OPEN_MAIN_DB) ){
+      /* These look like magic numbers. But they are stable, as they are part
+      ** of the definition of the SQLite file format, which may not change. */
+      u8 *pBuf = (u8*)zBuf;
+      p->iCookie = rbuGetU32(&pBuf[24]);
+      p->iWriteVer = pBuf[19];
+    }
+  }
+  return rc;
+}
+
+/*
+** Truncate an rbuVfs-file.
+*/
+static int rbuVfsTruncate(sqlite3_file *pFile, sqlite_int64 size){
+  rbu_file *p = (rbu_file*)pFile;
+  return p->pReal->pMethods->xTruncate(p->pReal, size);
+}
+
+/*
+** Sync an rbuVfs-file.
+*/
+static int rbuVfsSync(sqlite3_file *pFile, int flags){
+  rbu_file *p = (rbu_file *)pFile;
+  if( p->pRbu && p->pRbu->eStage==RBU_STAGE_CAPTURE ){
+    if( p->openFlags & SQLITE_OPEN_MAIN_DB ){
+      return SQLITE_INTERNAL;
+    }
+    return SQLITE_OK;
+  }
+  return p->pReal->pMethods->xSync(p->pReal, flags);
+}
+
+/*
+** Return the current file-size of an rbuVfs-file.
+*/
+static int rbuVfsFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){
+  rbu_file *p = (rbu_file *)pFile;
+  int rc;
+  rc = p->pReal->pMethods->xFileSize(p->pReal, pSize);
+
+  /* If this is an RBU vacuum operation and this is the target database,
+  ** pretend that it has at least one page. Otherwise, SQLite will not
+  ** check for the existance of a *-wal file. rbuVfsRead() contains 
+  ** similar logic.  */
+  if( rc==SQLITE_OK && *pSize==0 
+   && p->pRbu && rbuIsVacuum(p->pRbu) 
+   && (p->openFlags & SQLITE_OPEN_MAIN_DB)
+  ){
+    *pSize = 1024;
+  }
+  return rc;
+}
+
+/*
+** Lock an rbuVfs-file.
+*/
+static int rbuVfsLock(sqlite3_file *pFile, int eLock){
+  rbu_file *p = (rbu_file*)pFile;
+  sqlite3rbu *pRbu = p->pRbu;
+  int rc = SQLITE_OK;
+
+  assert( p->openFlags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_TEMP_DB) );
+  if( eLock==SQLITE_LOCK_EXCLUSIVE 
+   && (p->bNolock || (pRbu && pRbu->eStage!=RBU_STAGE_DONE))
+  ){
+    /* Do not allow EXCLUSIVE locks. Preventing SQLite from taking this 
+    ** prevents it from checkpointing the database from sqlite3_close(). */
+    rc = SQLITE_BUSY;
+  }else{
+    rc = p->pReal->pMethods->xLock(p->pReal, eLock);
+  }
+
+  return rc;
+}
+
+/*
+** Unlock an rbuVfs-file.
+*/
+static int rbuVfsUnlock(sqlite3_file *pFile, int eLock){
+  rbu_file *p = (rbu_file *)pFile;
+  return p->pReal->pMethods->xUnlock(p->pReal, eLock);
+}
+
+/*
+** Check if another file-handle holds a RESERVED lock on an rbuVfs-file.
+*/
+static int rbuVfsCheckReservedLock(sqlite3_file *pFile, int *pResOut){
+  rbu_file *p = (rbu_file *)pFile;
+  return p->pReal->pMethods->xCheckReservedLock(p->pReal, pResOut);
+}
+
+/*
+** File control method. For custom operations on an rbuVfs-file.
+*/
+static int rbuVfsFileControl(sqlite3_file *pFile, int op, void *pArg){
+  rbu_file *p = (rbu_file *)pFile;
+  int (*xControl)(sqlite3_file*,int,void*) = p->pReal->pMethods->xFileControl;
+  int rc;
+
+  assert( p->openFlags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_TEMP_DB)
+       || p->openFlags & (SQLITE_OPEN_TRANSIENT_DB|SQLITE_OPEN_TEMP_JOURNAL)
+  );
+  if( op==SQLITE_FCNTL_RBU ){
+    sqlite3rbu *pRbu = (sqlite3rbu*)pArg;
+
+    /* First try to find another RBU vfs lower down in the vfs stack. If
+    ** one is found, this vfs will operate in pass-through mode. The lower
+    ** level vfs will do the special RBU handling.  */
+    rc = xControl(p->pReal, op, pArg);
+
+    if( rc==SQLITE_NOTFOUND ){
+      /* Now search for a zipvfs instance lower down in the VFS stack. If
+      ** one is found, this is an error.  */
+      void *dummy = 0;
+      rc = xControl(p->pReal, SQLITE_FCNTL_ZIPVFS, &dummy);
+      if( rc==SQLITE_OK ){
+        rc = SQLITE_ERROR;
+        pRbu->zErrmsg = sqlite3_mprintf("rbu/zipvfs setup error");
+      }else if( rc==SQLITE_NOTFOUND ){
+        pRbu->pTargetFd = p;
+        p->pRbu = pRbu;
+        if( p->pWalFd ) p->pWalFd->pRbu = pRbu;
+        rc = SQLITE_OK;
+      }
+    }
+    return rc;
+  }
+  else if( op==SQLITE_FCNTL_RBUCNT ){
+    sqlite3rbu *pRbu = (sqlite3rbu*)pArg;
+    pRbu->nRbu++;
+    pRbu->pRbuFd = p;
+    p->bNolock = 1;
+  }
+
+  rc = xControl(p->pReal, op, pArg);
+  if( rc==SQLITE_OK && op==SQLITE_FCNTL_VFSNAME ){
+    rbu_vfs *pRbuVfs = p->pRbuVfs;
+    char *zIn = *(char**)pArg;
+    char *zOut = sqlite3_mprintf("rbu(%s)/%z", pRbuVfs->base.zName, zIn);
+    *(char**)pArg = zOut;
+    if( zOut==0 ) rc = SQLITE_NOMEM;
+  }
+
+  return rc;
+}
+
+/*
+** Return the sector-size in bytes for an rbuVfs-file.
+*/
+static int rbuVfsSectorSize(sqlite3_file *pFile){
+  rbu_file *p = (rbu_file *)pFile;
+  return p->pReal->pMethods->xSectorSize(p->pReal);
+}
+
+/*
+** Return the device characteristic flags supported by an rbuVfs-file.
+*/
+static int rbuVfsDeviceCharacteristics(sqlite3_file *pFile){
+  rbu_file *p = (rbu_file *)pFile;
+  return p->pReal->pMethods->xDeviceCharacteristics(p->pReal);
+}
+
+/*
+** Take or release a shared-memory lock.
+*/
+static int rbuVfsShmLock(sqlite3_file *pFile, int ofst, int n, int flags){
+  rbu_file *p = (rbu_file*)pFile;
+  sqlite3rbu *pRbu = p->pRbu;
+  int rc = SQLITE_OK;
+
+#ifdef SQLITE_AMALGAMATION
+    assert( WAL_CKPT_LOCK==1 );
+#endif
+
+  assert( p->openFlags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_TEMP_DB) );
+  if( pRbu && (pRbu->eStage==RBU_STAGE_OAL || pRbu->eStage==RBU_STAGE_MOVE) ){
+    /* Magic number 1 is the WAL_CKPT_LOCK lock. Preventing SQLite from
+    ** taking this lock also prevents any checkpoints from occurring. 
+    ** todo: really, it's not clear why this might occur, as 
+    ** wal_autocheckpoint ought to be turned off.  */
+    if( ofst==WAL_LOCK_CKPT && n==1 ) rc = SQLITE_BUSY;
+  }else{
+    int bCapture = 0;
+    if( n==1 && (flags & SQLITE_SHM_EXCLUSIVE)
+     && pRbu && pRbu->eStage==RBU_STAGE_CAPTURE
+     && (ofst==WAL_LOCK_WRITE || ofst==WAL_LOCK_CKPT || ofst==WAL_LOCK_READ0)
+    ){
+      bCapture = 1;
+    }
+
+    if( bCapture==0 || 0==(flags & SQLITE_SHM_UNLOCK) ){
+      rc = p->pReal->pMethods->xShmLock(p->pReal, ofst, n, flags);
+      if( bCapture && rc==SQLITE_OK ){
+        pRbu->mLock |= (1 << ofst);
+      }
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Obtain a pointer to a mapping of a single 32KiB page of the *-shm file.
+*/
+static int rbuVfsShmMap(
+  sqlite3_file *pFile, 
+  int iRegion, 
+  int szRegion, 
+  int isWrite, 
+  void volatile **pp
+){
+  rbu_file *p = (rbu_file*)pFile;
+  int rc = SQLITE_OK;
+  int eStage = (p->pRbu ? p->pRbu->eStage : 0);
+
+  /* If not in RBU_STAGE_OAL, allow this call to pass through. Or, if this
+  ** rbu is in the RBU_STAGE_OAL state, use heap memory for *-shm space 
+  ** instead of a file on disk.  */
+  assert( p->openFlags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_TEMP_DB) );
+  if( eStage==RBU_STAGE_OAL || eStage==RBU_STAGE_MOVE ){
+    if( iRegion<=p->nShm ){
+      int nByte = (iRegion+1) * sizeof(char*);
+      char **apNew = (char**)sqlite3_realloc64(p->apShm, nByte);
+      if( apNew==0 ){
+        rc = SQLITE_NOMEM;
+      }else{
+        memset(&apNew[p->nShm], 0, sizeof(char*) * (1 + iRegion - p->nShm));
+        p->apShm = apNew;
+        p->nShm = iRegion+1;
+      }
+    }
+
+    if( rc==SQLITE_OK && p->apShm[iRegion]==0 ){
+      char *pNew = (char*)sqlite3_malloc64(szRegion);
+      if( pNew==0 ){
+        rc = SQLITE_NOMEM;
+      }else{
+        memset(pNew, 0, szRegion);
+        p->apShm[iRegion] = pNew;
+      }
+    }
+
+    if( rc==SQLITE_OK ){
+      *pp = p->apShm[iRegion];
+    }else{
+      *pp = 0;
+    }
+  }else{
+    assert( p->apShm==0 );
+    rc = p->pReal->pMethods->xShmMap(p->pReal, iRegion, szRegion, isWrite, pp);
+  }
+
+  return rc;
+}
+
+/*
+** Memory barrier.
+*/
+static void rbuVfsShmBarrier(sqlite3_file *pFile){
+  rbu_file *p = (rbu_file *)pFile;
+  p->pReal->pMethods->xShmBarrier(p->pReal);
+}
+
+/*
+** The xShmUnmap method.
+*/
+static int rbuVfsShmUnmap(sqlite3_file *pFile, int delFlag){
+  rbu_file *p = (rbu_file*)pFile;
+  int rc = SQLITE_OK;
+  int eStage = (p->pRbu ? p->pRbu->eStage : 0);
+
+  assert( p->openFlags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_TEMP_DB) );
+  if( eStage==RBU_STAGE_OAL || eStage==RBU_STAGE_MOVE ){
+    /* no-op */
+  }else{
+    /* Release the checkpointer and writer locks */
+    rbuUnlockShm(p);
+    rc = p->pReal->pMethods->xShmUnmap(p->pReal, delFlag);
+  }
+  return rc;
+}
+
+/*
+** Given that zWal points to a buffer containing a wal file name passed to 
+** either the xOpen() or xAccess() VFS method, return a pointer to the
+** file-handle opened by the same database connection on the corresponding
+** database file.
+*/
+static rbu_file *rbuFindMaindb(rbu_vfs *pRbuVfs, const char *zWal){
+  rbu_file *pDb;
+  sqlite3_mutex_enter(pRbuVfs->mutex);
+  for(pDb=pRbuVfs->pMain; pDb && pDb->zWal!=zWal; pDb=pDb->pMainNext){}
+  sqlite3_mutex_leave(pRbuVfs->mutex);
+  return pDb;
+}
+
+/* 
+** A main database named zName has just been opened. The following 
+** function returns a pointer to a buffer owned by SQLite that contains
+** the name of the *-wal file this db connection will use. SQLite
+** happens to pass a pointer to this buffer when using xAccess()
+** or xOpen() to operate on the *-wal file.  
+*/
+static const char *rbuMainToWal(const char *zName, int flags){
+  int n = (int)strlen(zName);
+  const char *z = &zName[n];
+  if( flags & SQLITE_OPEN_URI ){
+    int odd = 0;
+    while( 1 ){
+      if( z[0]==0 ){
+        odd = 1 - odd;
+        if( odd && z[1]==0 ) break;
+      }
+      z++;
+    }
+    z += 2;
+  }else{
+    while( *z==0 ) z++;
+  }
+  z += (n + 8 + 1);
+  return z;
+}
+
+/*
+** Open an rbu file handle.
+*/
+static int rbuVfsOpen(
+  sqlite3_vfs *pVfs,
+  const char *zName,
+  sqlite3_file *pFile,
+  int flags,
+  int *pOutFlags
+){
+  static sqlite3_io_methods rbuvfs_io_methods = {
+    2,                            /* iVersion */
+    rbuVfsClose,                  /* xClose */
+    rbuVfsRead,                   /* xRead */
+    rbuVfsWrite,                  /* xWrite */
+    rbuVfsTruncate,               /* xTruncate */
+    rbuVfsSync,                   /* xSync */
+    rbuVfsFileSize,               /* xFileSize */
+    rbuVfsLock,                   /* xLock */
+    rbuVfsUnlock,                 /* xUnlock */
+    rbuVfsCheckReservedLock,      /* xCheckReservedLock */
+    rbuVfsFileControl,            /* xFileControl */
+    rbuVfsSectorSize,             /* xSectorSize */
+    rbuVfsDeviceCharacteristics,  /* xDeviceCharacteristics */
+    rbuVfsShmMap,                 /* xShmMap */
+    rbuVfsShmLock,                /* xShmLock */
+    rbuVfsShmBarrier,             /* xShmBarrier */
+    rbuVfsShmUnmap,               /* xShmUnmap */
+    0, 0                          /* xFetch, xUnfetch */
+  };
+  rbu_vfs *pRbuVfs = (rbu_vfs*)pVfs;
+  sqlite3_vfs *pRealVfs = pRbuVfs->pRealVfs;
+  rbu_file *pFd = (rbu_file *)pFile;
+  int rc = SQLITE_OK;
+  const char *zOpen = zName;
+  int oflags = flags;
+
+  memset(pFd, 0, sizeof(rbu_file));
+  pFd->pReal = (sqlite3_file*)&pFd[1];
+  pFd->pRbuVfs = pRbuVfs;
+  pFd->openFlags = flags;
+  if( zName ){
+    if( flags & SQLITE_OPEN_MAIN_DB ){
+      /* A main database has just been opened. The following block sets
+      ** (pFd->zWal) to point to a buffer owned by SQLite that contains
+      ** the name of the *-wal file this db connection will use. SQLite
+      ** happens to pass a pointer to this buffer when using xAccess()
+      ** or xOpen() to operate on the *-wal file.  */
+      pFd->zWal = rbuMainToWal(zName, flags);
+    }
+    else if( flags & SQLITE_OPEN_WAL ){
+      rbu_file *pDb = rbuFindMaindb(pRbuVfs, zName);
+      if( pDb ){
+        if( pDb->pRbu && pDb->pRbu->eStage==RBU_STAGE_OAL ){
+          /* This call is to open a *-wal file. Intead, open the *-oal. This
+          ** code ensures that the string passed to xOpen() is terminated by a
+          ** pair of '\0' bytes in case the VFS attempts to extract a URI 
+          ** parameter from it.  */
+          const char *zBase = zName;
+          size_t nCopy;
+          char *zCopy;
+          if( rbuIsVacuum(pDb->pRbu) ){
+            zBase = sqlite3_db_filename(pDb->pRbu->dbRbu, "main");
+            zBase = rbuMainToWal(zBase, SQLITE_OPEN_URI);
+          }
+          nCopy = strlen(zBase);
+          zCopy = sqlite3_malloc64(nCopy+2);
+          if( zCopy ){
+            memcpy(zCopy, zBase, nCopy);
+            zCopy[nCopy-3] = 'o';
+            zCopy[nCopy] = '\0';
+            zCopy[nCopy+1] = '\0';
+            zOpen = (const char*)(pFd->zDel = zCopy);
+          }else{
+            rc = SQLITE_NOMEM;
+          }
+          pFd->pRbu = pDb->pRbu;
+        }
+        pDb->pWalFd = pFd;
+      }
+    }
+  }
+
+  if( oflags & SQLITE_OPEN_MAIN_DB 
+   && sqlite3_uri_boolean(zName, "rbu_memory", 0) 
+  ){
+    assert( oflags & SQLITE_OPEN_MAIN_DB );
+    oflags =  SQLITE_OPEN_TEMP_DB | SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE |
+              SQLITE_OPEN_EXCLUSIVE | SQLITE_OPEN_DELETEONCLOSE;
+    zOpen = 0;
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = pRealVfs->xOpen(pRealVfs, zOpen, pFd->pReal, oflags, pOutFlags);
+  }
+  if( pFd->pReal->pMethods ){
+    /* The xOpen() operation has succeeded. Set the sqlite3_file.pMethods
+    ** pointer and, if the file is a main database file, link it into the
+    ** mutex protected linked list of all such files.  */
+    pFile->pMethods = &rbuvfs_io_methods;
+    if( flags & SQLITE_OPEN_MAIN_DB ){
+      sqlite3_mutex_enter(pRbuVfs->mutex);
+      pFd->pMainNext = pRbuVfs->pMain;
+      pRbuVfs->pMain = pFd;
+      sqlite3_mutex_leave(pRbuVfs->mutex);
+    }
+  }else{
+    sqlite3_free(pFd->zDel);
+  }
+
+  return rc;
+}
+
+/*
+** Delete the file located at zPath.
+*/
+static int rbuVfsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
+  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
+  return pRealVfs->xDelete(pRealVfs, zPath, dirSync);
+}
+
+/*
+** Test for access permissions. Return true if the requested permission
+** is available, or false otherwise.
+*/
+static int rbuVfsAccess(
+  sqlite3_vfs *pVfs, 
+  const char *zPath, 
+  int flags, 
+  int *pResOut
+){
+  rbu_vfs *pRbuVfs = (rbu_vfs*)pVfs;
+  sqlite3_vfs *pRealVfs = pRbuVfs->pRealVfs;
+  int rc;
+
+  rc = pRealVfs->xAccess(pRealVfs, zPath, flags, pResOut);
+
+  /* If this call is to check if a *-wal file associated with an RBU target
+  ** database connection exists, and the RBU update is in RBU_STAGE_OAL,
+  ** the following special handling is activated:
+  **
+  **   a) if the *-wal file does exist, return SQLITE_CANTOPEN. This
+  **      ensures that the RBU extension never tries to update a database
+  **      in wal mode, even if the first page of the database file has
+  **      been damaged. 
+  **
+  **   b) if the *-wal file does not exist, claim that it does anyway,
+  **      causing SQLite to call xOpen() to open it. This call will also
+  **      be intercepted (see the rbuVfsOpen() function) and the *-oal
+  **      file opened instead.
+  */
+  if( rc==SQLITE_OK && flags==SQLITE_ACCESS_EXISTS ){
+    rbu_file *pDb = rbuFindMaindb(pRbuVfs, zPath);
+    if( pDb && pDb->pRbu && pDb->pRbu->eStage==RBU_STAGE_OAL ){
+      if( *pResOut ){
+        rc = SQLITE_CANTOPEN;
+      }else{
+        *pResOut = 1;
+      }
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Populate buffer zOut with the full canonical pathname corresponding
+** to the pathname in zPath. zOut is guaranteed to point to a buffer
+** of at least (DEVSYM_MAX_PATHNAME+1) bytes.
+*/
+static int rbuVfsFullPathname(
+  sqlite3_vfs *pVfs, 
+  const char *zPath, 
+  int nOut, 
+  char *zOut
+){
+  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
+  return pRealVfs->xFullPathname(pRealVfs, zPath, nOut, zOut);
+}
+
+#ifndef SQLITE_OMIT_LOAD_EXTENSION
+/*
+** Open the dynamic library located at zPath and return a handle.
+*/
+static void *rbuVfsDlOpen(sqlite3_vfs *pVfs, const char *zPath){
+  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
+  return pRealVfs->xDlOpen(pRealVfs, zPath);
+}
+
+/*
+** Populate the buffer zErrMsg (size nByte bytes) with a human readable
+** utf-8 string describing the most recent error encountered associated 
+** with dynamic libraries.
+*/
+static void rbuVfsDlError(sqlite3_vfs *pVfs, int nByte, char *zErrMsg){
+  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
+  pRealVfs->xDlError(pRealVfs, nByte, zErrMsg);
+}
+
+/*
+** Return a pointer to the symbol zSymbol in the dynamic library pHandle.
+*/
+static void (*rbuVfsDlSym(
+  sqlite3_vfs *pVfs, 
+  void *pArg, 
+  const char *zSym
+))(void){
+  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
+  return pRealVfs->xDlSym(pRealVfs, pArg, zSym);
+}
+
+/*
+** Close the dynamic library handle pHandle.
+*/
+static void rbuVfsDlClose(sqlite3_vfs *pVfs, void *pHandle){
+  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
+  pRealVfs->xDlClose(pRealVfs, pHandle);
+}
+#endif /* SQLITE_OMIT_LOAD_EXTENSION */
+
+/*
+** Populate the buffer pointed to by zBufOut with nByte bytes of 
+** random data.
+*/
+static int rbuVfsRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
+  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
+  return pRealVfs->xRandomness(pRealVfs, nByte, zBufOut);
+}
+
+/*
+** Sleep for nMicro microseconds. Return the number of microseconds 
+** actually slept.
+*/
+static int rbuVfsSleep(sqlite3_vfs *pVfs, int nMicro){
+  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
+  return pRealVfs->xSleep(pRealVfs, nMicro);
+}
+
+/*
+** Return the current time as a Julian Day number in *pTimeOut.
+*/
+static int rbuVfsCurrentTime(sqlite3_vfs *pVfs, double *pTimeOut){
+  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
+  return pRealVfs->xCurrentTime(pRealVfs, pTimeOut);
+}
+
+/*
+** No-op.
+*/
+static int rbuVfsGetLastError(sqlite3_vfs *pVfs, int a, char *b){
+  return 0;
+}
+
+/*
+** Deregister and destroy an RBU vfs created by an earlier call to
+** sqlite3rbu_create_vfs().
+*/
+SQLITE_API void sqlite3rbu_destroy_vfs(const char *zName){
+  sqlite3_vfs *pVfs = sqlite3_vfs_find(zName);
+  if( pVfs && pVfs->xOpen==rbuVfsOpen ){
+    sqlite3_mutex_free(((rbu_vfs*)pVfs)->mutex);
+    sqlite3_vfs_unregister(pVfs);
+    sqlite3_free(pVfs);
+  }
+}
+
+/*
+** Create an RBU VFS named zName that accesses the underlying file-system
+** via existing VFS zParent. The new object is registered as a non-default
+** VFS with SQLite before returning.
+*/
+SQLITE_API int sqlite3rbu_create_vfs(const char *zName, const char *zParent){
+
+  /* Template for VFS */
+  static sqlite3_vfs vfs_template = {
+    1,                            /* iVersion */
+    0,                            /* szOsFile */
+    0,                            /* mxPathname */
+    0,                            /* pNext */
+    0,                            /* zName */
+    0,                            /* pAppData */
+    rbuVfsOpen,                   /* xOpen */
+    rbuVfsDelete,                 /* xDelete */
+    rbuVfsAccess,                 /* xAccess */
+    rbuVfsFullPathname,           /* xFullPathname */
+
+#ifndef SQLITE_OMIT_LOAD_EXTENSION
+    rbuVfsDlOpen,                 /* xDlOpen */
+    rbuVfsDlError,                /* xDlError */
+    rbuVfsDlSym,                  /* xDlSym */
+    rbuVfsDlClose,                /* xDlClose */
+#else
+    0, 0, 0, 0,
+#endif
+
+    rbuVfsRandomness,             /* xRandomness */
+    rbuVfsSleep,                  /* xSleep */
+    rbuVfsCurrentTime,            /* xCurrentTime */
+    rbuVfsGetLastError,           /* xGetLastError */
+    0,                            /* xCurrentTimeInt64 (version 2) */
+    0, 0, 0                       /* Unimplemented version 3 methods */
+  };
+
+  rbu_vfs *pNew = 0;              /* Newly allocated VFS */
+  int rc = SQLITE_OK;
+  size_t nName;
+  size_t nByte;
+
+  nName = strlen(zName);
+  nByte = sizeof(rbu_vfs) + nName + 1;
+  pNew = (rbu_vfs*)sqlite3_malloc64(nByte);
+  if( pNew==0 ){
+    rc = SQLITE_NOMEM;
+  }else{
+    sqlite3_vfs *pParent;           /* Parent VFS */
+    memset(pNew, 0, nByte);
+    pParent = sqlite3_vfs_find(zParent);
+    if( pParent==0 ){
+      rc = SQLITE_NOTFOUND;
+    }else{
+      char *zSpace;
+      memcpy(&pNew->base, &vfs_template, sizeof(sqlite3_vfs));
+      pNew->base.mxPathname = pParent->mxPathname;
+      pNew->base.szOsFile = sizeof(rbu_file) + pParent->szOsFile;
+      pNew->pRealVfs = pParent;
+      pNew->base.zName = (const char*)(zSpace = (char*)&pNew[1]);
+      memcpy(zSpace, zName, nName);
+
+      /* Allocate the mutex and register the new VFS (not as the default) */
+      pNew->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_RECURSIVE);
+      if( pNew->mutex==0 ){
+        rc = SQLITE_NOMEM;
+      }else{
+        rc = sqlite3_vfs_register(&pNew->base, 0);
+      }
+    }
+
+    if( rc!=SQLITE_OK ){
+      sqlite3_mutex_free(pNew->mutex);
+      sqlite3_free(pNew);
+    }
+  }
+
+  return rc;
+}
+
+
+/**************************************************************************/
+
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_RBU) */
+
+/************** End of sqlite3rbu.c ******************************************/
+/************** Begin file dbstat.c ******************************************/
+/*
+** 2010 July 12
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains an implementation of the "dbstat" virtual table.
+**
+** The dbstat virtual table is used to extract low-level formatting
+** information from an SQLite database in order to implement the
+** "sqlite3_analyzer" utility.  See the ../tool/spaceanal.tcl script
+** for an example implementation.
+**
+** Additional information is available on the "dbstat.html" page of the
+** official SQLite documentation.
+*/
+
+/* #include "sqliteInt.h"   ** Requires access to internal data structures ** */
+#if (defined(SQLITE_ENABLE_DBSTAT_VTAB) || defined(SQLITE_TEST)) \
+    && !defined(SQLITE_OMIT_VIRTUALTABLE)
+
+/*
+** Page paths:
+** 
+**   The value of the 'path' column describes the path taken from the 
+**   root-node of the b-tree structure to each page. The value of the 
+**   root-node path is '/'.
+**
+**   The value of the path for the left-most child page of the root of
+**   a b-tree is '/000/'. (Btrees store content ordered from left to right
+**   so the pages to the left have smaller keys than the pages to the right.)
+**   The next to left-most child of the root page is
+**   '/001', and so on, each sibling page identified by a 3-digit hex 
+**   value. The children of the 451st left-most sibling have paths such
+**   as '/1c2/000/, '/1c2/001/' etc.
+**
+**   Overflow pages are specified by appending a '+' character and a 
+**   six-digit hexadecimal value to the path to the cell they are linked
+**   from. For example, the three overflow pages in a chain linked from 
+**   the left-most cell of the 450th child of the root page are identified
+**   by the paths:
+**
+**      '/1c2/000+000000'         // First page in overflow chain
+**      '/1c2/000+000001'         // Second page in overflow chain
+**      '/1c2/000+000002'         // Third page in overflow chain
+**
+**   If the paths are sorted using the BINARY collation sequence, then
+**   the overflow pages associated with a cell will appear earlier in the
+**   sort-order than its child page:
+**
+**      '/1c2/000/'               // Left-most child of 451st child of root
+*/
+#define VTAB_SCHEMA                                                         \
+  "CREATE TABLE xx( "                                                       \
+  "  name       TEXT,             /* Name of table or index */"             \
+  "  path       TEXT,             /* Path to page from root */"             \
+  "  pageno     INTEGER,          /* Page number */"                        \
+  "  pagetype   TEXT,             /* 'internal', 'leaf' or 'overflow' */"   \
+  "  ncell      INTEGER,          /* Cells on page (0 for overflow) */"     \
+  "  payload    INTEGER,          /* Bytes of payload on this page */"      \
+  "  unused     INTEGER,          /* Bytes of unused space on this page */" \
+  "  mx_payload INTEGER,          /* Largest payload size of all cells */"  \
+  "  pgoffset   INTEGER,          /* Offset of page in file */"             \
+  "  pgsize     INTEGER,          /* Size of the page */"                   \
+  "  schema     TEXT HIDDEN       /* Database schema being analyzed */"     \
+  ");"
+
+
+typedef struct StatTable StatTable;
+typedef struct StatCursor StatCursor;
+typedef struct StatPage StatPage;
+typedef struct StatCell StatCell;
+
+struct StatCell {
+  int nLocal;                     /* Bytes of local payload */
+  u32 iChildPg;                   /* Child node (or 0 if this is a leaf) */
+  int nOvfl;                      /* Entries in aOvfl[] */
+  u32 *aOvfl;                     /* Array of overflow page numbers */
+  int nLastOvfl;                  /* Bytes of payload on final overflow page */
+  int iOvfl;                      /* Iterates through aOvfl[] */
+};
+
+struct StatPage {
+  u32 iPgno;
+  DbPage *pPg;
+  int iCell;
+
+  char *zPath;                    /* Path to this page */
+
+  /* Variables populated by statDecodePage(): */
+  u8 flags;                       /* Copy of flags byte */
+  int nCell;                      /* Number of cells on page */
+  int nUnused;                    /* Number of unused bytes on page */
+  StatCell *aCell;                /* Array of parsed cells */
+  u32 iRightChildPg;              /* Right-child page number (or 0) */
+  int nMxPayload;                 /* Largest payload of any cell on this page */
+};
+
+struct StatCursor {
+  sqlite3_vtab_cursor base;
+  sqlite3_stmt *pStmt;            /* Iterates through set of root pages */
+  int isEof;                      /* After pStmt has returned SQLITE_DONE */
+  int iDb;                        /* Schema used for this query */
+
+  StatPage aPage[32];
+  int iPage;                      /* Current entry in aPage[] */
+
+  /* Values to return. */
+  char *zName;                    /* Value of 'name' column */
+  char *zPath;                    /* Value of 'path' column */
+  u32 iPageno;                    /* Value of 'pageno' column */
+  char *zPagetype;                /* Value of 'pagetype' column */
+  int nCell;                      /* Value of 'ncell' column */
+  int nPayload;                   /* Value of 'payload' column */
+  int nUnused;                    /* Value of 'unused' column */
+  int nMxPayload;                 /* Value of 'mx_payload' column */
+  i64 iOffset;                    /* Value of 'pgOffset' column */
+  int szPage;                     /* Value of 'pgSize' column */
+};
+
+struct StatTable {
+  sqlite3_vtab base;
+  sqlite3 *db;
+  int iDb;                        /* Index of database to analyze */
+};
+
+#ifndef get2byte
+# define get2byte(x)   ((x)[0]<<8 | (x)[1])
+#endif
+
+/*
+** Connect to or create a statvfs virtual table.
+*/
+static int statConnect(
+  sqlite3 *db,
+  void *pAux,
+  int argc, const char *const*argv,
+  sqlite3_vtab **ppVtab,
+  char **pzErr
+){
+  StatTable *pTab = 0;
+  int rc = SQLITE_OK;
+  int iDb;
+
+  if( argc>=4 ){
+    Token nm;
+    sqlite3TokenInit(&nm, (char*)argv[3]);
+    iDb = sqlite3FindDb(db, &nm);
+    if( iDb<0 ){
+      *pzErr = sqlite3_mprintf("no such database: %s", argv[3]);
+      return SQLITE_ERROR;
+    }
+  }else{
+    iDb = 0;
+  }
+  rc = sqlite3_declare_vtab(db, VTAB_SCHEMA);
+  if( rc==SQLITE_OK ){
+    pTab = (StatTable *)sqlite3_malloc64(sizeof(StatTable));
+    if( pTab==0 ) rc = SQLITE_NOMEM_BKPT;
+  }
+
+  assert( rc==SQLITE_OK || pTab==0 );
+  if( rc==SQLITE_OK ){
+    memset(pTab, 0, sizeof(StatTable));
+    pTab->db = db;
+    pTab->iDb = iDb;
+  }
+
+  *ppVtab = (sqlite3_vtab*)pTab;
+  return rc;
+}
+
+/*
+** Disconnect from or destroy a statvfs virtual table.
+*/
+static int statDisconnect(sqlite3_vtab *pVtab){
+  sqlite3_free(pVtab);
+  return SQLITE_OK;
+}
+
+/*
+** There is no "best-index". This virtual table always does a linear
+** scan.  However, a schema=? constraint should cause this table to
+** operate on a different database schema, so check for it.
+**
+** idxNum is normally 0, but will be 1 if a schema=? constraint exists.
+*/
+static int statBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
+  int i;
+
+  pIdxInfo->estimatedCost = 1.0e6;  /* Initial cost estimate */
+
+  /* Look for a valid schema=? constraint.  If found, change the idxNum to
+  ** 1 and request the value of that constraint be sent to xFilter.  And
+  ** lower the cost estimate to encourage the constrained version to be
+  ** used.
+  */
+  for(i=0; i<pIdxInfo->nConstraint; i++){
+    if( pIdxInfo->aConstraint[i].usable==0 ) continue;
+    if( pIdxInfo->aConstraint[i].op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
+    if( pIdxInfo->aConstraint[i].iColumn!=10 ) continue;
+    pIdxInfo->idxNum = 1;
+    pIdxInfo->estimatedCost = 1.0;
+    pIdxInfo->aConstraintUsage[i].argvIndex = 1;
+    pIdxInfo->aConstraintUsage[i].omit = 1;
+    break;
+  }
+
+
+  /* Records are always returned in ascending order of (name, path). 
+  ** If this will satisfy the client, set the orderByConsumed flag so that 
+  ** SQLite does not do an external sort.
+  */
+  if( ( pIdxInfo->nOrderBy==1
+     && pIdxInfo->aOrderBy[0].iColumn==0
+     && pIdxInfo->aOrderBy[0].desc==0
+     ) ||
+      ( pIdxInfo->nOrderBy==2
+     && pIdxInfo->aOrderBy[0].iColumn==0
+     && pIdxInfo->aOrderBy[0].desc==0
+     && pIdxInfo->aOrderBy[1].iColumn==1
+     && pIdxInfo->aOrderBy[1].desc==0
+     )
+  ){
+    pIdxInfo->orderByConsumed = 1;
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Open a new statvfs cursor.
+*/
+static int statOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){
+  StatTable *pTab = (StatTable *)pVTab;
+  StatCursor *pCsr;
+
+  pCsr = (StatCursor *)sqlite3_malloc64(sizeof(StatCursor));
+  if( pCsr==0 ){
+    return SQLITE_NOMEM_BKPT;
+  }else{
+    memset(pCsr, 0, sizeof(StatCursor));
+    pCsr->base.pVtab = pVTab;
+    pCsr->iDb = pTab->iDb;
+  }
+
+  *ppCursor = (sqlite3_vtab_cursor *)pCsr;
+  return SQLITE_OK;
+}
+
+static void statClearPage(StatPage *p){
+  int i;
+  if( p->aCell ){
+    for(i=0; i<p->nCell; i++){
+      sqlite3_free(p->aCell[i].aOvfl);
+    }
+    sqlite3_free(p->aCell);
+  }
+  sqlite3PagerUnref(p->pPg);
+  sqlite3_free(p->zPath);
+  memset(p, 0, sizeof(StatPage));
+}
+
+static void statResetCsr(StatCursor *pCsr){
+  int i;
+  sqlite3_reset(pCsr->pStmt);
+  for(i=0; i<ArraySize(pCsr->aPage); i++){
+    statClearPage(&pCsr->aPage[i]);
+  }
+  pCsr->iPage = 0;
+  sqlite3_free(pCsr->zPath);
+  pCsr->zPath = 0;
+  pCsr->isEof = 0;
+}
+
+/*
+** Close a statvfs cursor.
+*/
+static int statClose(sqlite3_vtab_cursor *pCursor){
+  StatCursor *pCsr = (StatCursor *)pCursor;
+  statResetCsr(pCsr);
+  sqlite3_finalize(pCsr->pStmt);
+  sqlite3_free(pCsr);
+  return SQLITE_OK;
+}
+
+static void getLocalPayload(
+  int nUsable,                    /* Usable bytes per page */
+  u8 flags,                       /* Page flags */
+  int nTotal,                     /* Total record (payload) size */
+  int *pnLocal                    /* OUT: Bytes stored locally */
+){
+  int nLocal;
+  int nMinLocal;
+  int nMaxLocal;
+ 
+  if( flags==0x0D ){              /* Table leaf node */
+    nMinLocal = (nUsable - 12) * 32 / 255 - 23;
+    nMaxLocal = nUsable - 35;
+  }else{                          /* Index interior and leaf nodes */
+    nMinLocal = (nUsable - 12) * 32 / 255 - 23;
+    nMaxLocal = (nUsable - 12) * 64 / 255 - 23;
+  }
+
+  nLocal = nMinLocal + (nTotal - nMinLocal) % (nUsable - 4);
+  if( nLocal>nMaxLocal ) nLocal = nMinLocal;
+  *pnLocal = nLocal;
+}
+
+static int statDecodePage(Btree *pBt, StatPage *p){
+  int nUnused;
+  int iOff;
+  int nHdr;
+  int isLeaf;
+  int szPage;
+
+  u8 *aData = sqlite3PagerGetData(p->pPg);
+  u8 *aHdr = &aData[p->iPgno==1 ? 100 : 0];
+
+  p->flags = aHdr[0];
+  p->nCell = get2byte(&aHdr[3]);
+  p->nMxPayload = 0;
+
+  isLeaf = (p->flags==0x0A || p->flags==0x0D);
+  nHdr = 12 - isLeaf*4 + (p->iPgno==1)*100;
+
+  nUnused = get2byte(&aHdr[5]) - nHdr - 2*p->nCell;
+  nUnused += (int)aHdr[7];
+  iOff = get2byte(&aHdr[1]);
+  while( iOff ){
+    nUnused += get2byte(&aData[iOff+2]);
+    iOff = get2byte(&aData[iOff]);
+  }
+  p->nUnused = nUnused;
+  p->iRightChildPg = isLeaf ? 0 : sqlite3Get4byte(&aHdr[8]);
+  szPage = sqlite3BtreeGetPageSize(pBt);
+
+  if( p->nCell ){
+    int i;                        /* Used to iterate through cells */
+    int nUsable;                  /* Usable bytes per page */
+
+    sqlite3BtreeEnter(pBt);
+    nUsable = szPage - sqlite3BtreeGetReserveNoMutex(pBt);
+    sqlite3BtreeLeave(pBt);
+    p->aCell = sqlite3_malloc64((p->nCell+1) * sizeof(StatCell));
+    if( p->aCell==0 ) return SQLITE_NOMEM_BKPT;
+    memset(p->aCell, 0, (p->nCell+1) * sizeof(StatCell));
+
+    for(i=0; i<p->nCell; i++){
+      StatCell *pCell = &p->aCell[i];
+
+      iOff = get2byte(&aData[nHdr+i*2]);
+      if( !isLeaf ){
+        pCell->iChildPg = sqlite3Get4byte(&aData[iOff]);
+        iOff += 4;
+      }
+      if( p->flags==0x05 ){
+        /* A table interior node. nPayload==0. */
+      }else{
+        u32 nPayload;             /* Bytes of payload total (local+overflow) */
+        int nLocal;               /* Bytes of payload stored locally */
+        iOff += getVarint32(&aData[iOff], nPayload);
+        if( p->flags==0x0D ){
+          u64 dummy;
+          iOff += sqlite3GetVarint(&aData[iOff], &dummy);
+        }
+        if( nPayload>(u32)p->nMxPayload ) p->nMxPayload = nPayload;
+        getLocalPayload(nUsable, p->flags, nPayload, &nLocal);
+        pCell->nLocal = nLocal;
+        assert( nLocal>=0 );
+        assert( nPayload>=(u32)nLocal );
+        assert( nLocal<=(nUsable-35) );
+        if( nPayload>(u32)nLocal ){
+          int j;
+          int nOvfl = ((nPayload - nLocal) + nUsable-4 - 1) / (nUsable - 4);
+          pCell->nLastOvfl = (nPayload-nLocal) - (nOvfl-1) * (nUsable-4);
+          pCell->nOvfl = nOvfl;
+          pCell->aOvfl = sqlite3_malloc64(sizeof(u32)*nOvfl);
+          if( pCell->aOvfl==0 ) return SQLITE_NOMEM_BKPT;
+          pCell->aOvfl[0] = sqlite3Get4byte(&aData[iOff+nLocal]);
+          for(j=1; j<nOvfl; j++){
+            int rc;
+            u32 iPrev = pCell->aOvfl[j-1];
+            DbPage *pPg = 0;
+            rc = sqlite3PagerGet(sqlite3BtreePager(pBt), iPrev, &pPg, 0);
+            if( rc!=SQLITE_OK ){
+              assert( pPg==0 );
+              return rc;
+            } 
+            pCell->aOvfl[j] = sqlite3Get4byte(sqlite3PagerGetData(pPg));
+            sqlite3PagerUnref(pPg);
+          }
+        }
+      }
+    }
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Populate the pCsr->iOffset and pCsr->szPage member variables. Based on
+** the current value of pCsr->iPageno.
+*/
+static void statSizeAndOffset(StatCursor *pCsr){
+  StatTable *pTab = (StatTable *)((sqlite3_vtab_cursor *)pCsr)->pVtab;
+  Btree *pBt = pTab->db->aDb[pTab->iDb].pBt;
+  Pager *pPager = sqlite3BtreePager(pBt);
+  sqlite3_file *fd;
+  sqlite3_int64 x[2];
+
+  /* The default page size and offset */
+  pCsr->szPage = sqlite3BtreeGetPageSize(pBt);
+  pCsr->iOffset = (i64)pCsr->szPage * (pCsr->iPageno - 1);
+
+  /* If connected to a ZIPVFS backend, override the page size and
+  ** offset with actual values obtained from ZIPVFS.
+  */
+  fd = sqlite3PagerFile(pPager);
+  x[0] = pCsr->iPageno;
+  if( fd->pMethods!=0 && sqlite3OsFileControl(fd, 230440, &x)==SQLITE_OK ){
+    pCsr->iOffset = x[0];
+    pCsr->szPage = (int)x[1];
+  }
+}
+
+/*
+** Move a statvfs cursor to the next entry in the file.
+*/
+static int statNext(sqlite3_vtab_cursor *pCursor){
+  int rc;
+  int nPayload;
+  char *z;
+  StatCursor *pCsr = (StatCursor *)pCursor;
+  StatTable *pTab = (StatTable *)pCursor->pVtab;
+  Btree *pBt = pTab->db->aDb[pCsr->iDb].pBt;
+  Pager *pPager = sqlite3BtreePager(pBt);
+
+  sqlite3_free(pCsr->zPath);
+  pCsr->zPath = 0;
+
+statNextRestart:
+  if( pCsr->aPage[0].pPg==0 ){
+    rc = sqlite3_step(pCsr->pStmt);
+    if( rc==SQLITE_ROW ){
+      int nPage;
+      u32 iRoot = (u32)sqlite3_column_int64(pCsr->pStmt, 1);
+      sqlite3PagerPagecount(pPager, &nPage);
+      if( nPage==0 ){
+        pCsr->isEof = 1;
+        return sqlite3_reset(pCsr->pStmt);
+      }
+      rc = sqlite3PagerGet(pPager, iRoot, &pCsr->aPage[0].pPg, 0);
+      pCsr->aPage[0].iPgno = iRoot;
+      pCsr->aPage[0].iCell = 0;
+      pCsr->aPage[0].zPath = z = sqlite3_mprintf("/");
+      pCsr->iPage = 0;
+      if( z==0 ) rc = SQLITE_NOMEM_BKPT;
+    }else{
+      pCsr->isEof = 1;
+      return sqlite3_reset(pCsr->pStmt);
+    }
+  }else{
+
+    /* Page p itself has already been visited. */
+    StatPage *p = &pCsr->aPage[pCsr->iPage];
+
+    while( p->iCell<p->nCell ){
+      StatCell *pCell = &p->aCell[p->iCell];
+      if( pCell->iOvfl<pCell->nOvfl ){
+        int nUsable;
+        sqlite3BtreeEnter(pBt);
+        nUsable = sqlite3BtreeGetPageSize(pBt) - 
+                        sqlite3BtreeGetReserveNoMutex(pBt);
+        sqlite3BtreeLeave(pBt);
+        pCsr->zName = (char *)sqlite3_column_text(pCsr->pStmt, 0);
+        pCsr->iPageno = pCell->aOvfl[pCell->iOvfl];
+        pCsr->zPagetype = "overflow";
+        pCsr->nCell = 0;
+        pCsr->nMxPayload = 0;
+        pCsr->zPath = z = sqlite3_mprintf(
+            "%s%.3x+%.6x", p->zPath, p->iCell, pCell->iOvfl
+        );
+        if( pCell->iOvfl<pCell->nOvfl-1 ){
+          pCsr->nUnused = 0;
+          pCsr->nPayload = nUsable - 4;
+        }else{
+          pCsr->nPayload = pCell->nLastOvfl;
+          pCsr->nUnused = nUsable - 4 - pCsr->nPayload;
+        }
+        pCell->iOvfl++;
+        statSizeAndOffset(pCsr);
+        return z==0 ? SQLITE_NOMEM_BKPT : SQLITE_OK;
+      }
+      if( p->iRightChildPg ) break;
+      p->iCell++;
+    }
+
+    if( !p->iRightChildPg || p->iCell>p->nCell ){
+      statClearPage(p);
+      if( pCsr->iPage==0 ) return statNext(pCursor);
+      pCsr->iPage--;
+      goto statNextRestart; /* Tail recursion */
+    }
+    pCsr->iPage++;
+    assert( p==&pCsr->aPage[pCsr->iPage-1] );
+
+    if( p->iCell==p->nCell ){
+      p[1].iPgno = p->iRightChildPg;
+    }else{
+      p[1].iPgno = p->aCell[p->iCell].iChildPg;
+    }
+    rc = sqlite3PagerGet(pPager, p[1].iPgno, &p[1].pPg, 0);
+    p[1].iCell = 0;
+    p[1].zPath = z = sqlite3_mprintf("%s%.3x/", p->zPath, p->iCell);
+    p->iCell++;
+    if( z==0 ) rc = SQLITE_NOMEM_BKPT;
+  }
+
+
+  /* Populate the StatCursor fields with the values to be returned
+  ** by the xColumn() and xRowid() methods.
+  */
+  if( rc==SQLITE_OK ){
+    int i;
+    StatPage *p = &pCsr->aPage[pCsr->iPage];
+    pCsr->zName = (char *)sqlite3_column_text(pCsr->pStmt, 0);
+    pCsr->iPageno = p->iPgno;
+
+    rc = statDecodePage(pBt, p);
+    if( rc==SQLITE_OK ){
+      statSizeAndOffset(pCsr);
+
+      switch( p->flags ){
+        case 0x05:             /* table internal */
+        case 0x02:             /* index internal */
+          pCsr->zPagetype = "internal";
+          break;
+        case 0x0D:             /* table leaf */
+        case 0x0A:             /* index leaf */
+          pCsr->zPagetype = "leaf";
+          break;
+        default:
+          pCsr->zPagetype = "corrupted";
+          break;
+      }
+      pCsr->nCell = p->nCell;
+      pCsr->nUnused = p->nUnused;
+      pCsr->nMxPayload = p->nMxPayload;
+      pCsr->zPath = z = sqlite3_mprintf("%s", p->zPath);
+      if( z==0 ) rc = SQLITE_NOMEM_BKPT;
+      nPayload = 0;
+      for(i=0; i<p->nCell; i++){
+        nPayload += p->aCell[i].nLocal;
+      }
+      pCsr->nPayload = nPayload;
+    }
+  }
+
+  return rc;
+}
+
+static int statEof(sqlite3_vtab_cursor *pCursor){
+  StatCursor *pCsr = (StatCursor *)pCursor;
+  return pCsr->isEof;
+}
+
+static int statFilter(
+  sqlite3_vtab_cursor *pCursor, 
+  int idxNum, const char *idxStr,
+  int argc, sqlite3_value **argv
+){
+  StatCursor *pCsr = (StatCursor *)pCursor;
+  StatTable *pTab = (StatTable*)(pCursor->pVtab);
+  char *zSql;
+  int rc = SQLITE_OK;
+  char *zMaster;
+
+  if( idxNum==1 ){
+    const char *zDbase = (const char*)sqlite3_value_text(argv[0]);
+    pCsr->iDb = sqlite3FindDbName(pTab->db, zDbase);
+    if( pCsr->iDb<0 ){
+      sqlite3_free(pCursor->pVtab->zErrMsg);
+      pCursor->pVtab->zErrMsg = sqlite3_mprintf("no such schema: %s", zDbase);
+      return pCursor->pVtab->zErrMsg ? SQLITE_ERROR : SQLITE_NOMEM_BKPT;
+    }
+  }else{
+    pCsr->iDb = pTab->iDb;
+  }
+  statResetCsr(pCsr);
+  sqlite3_finalize(pCsr->pStmt);
+  pCsr->pStmt = 0;
+  zMaster = pCsr->iDb==1 ? "sqlite_temp_master" : "sqlite_master";
+  zSql = sqlite3_mprintf(
+      "SELECT 'sqlite_master' AS name, 1 AS rootpage, 'table' AS type"
+      "  UNION ALL  "
+      "SELECT name, rootpage, type"
+      "  FROM \"%w\".%s WHERE rootpage!=0"
+      "  ORDER BY name", pTab->db->aDb[pCsr->iDb].zDbSName, zMaster);
+  if( zSql==0 ){
+    return SQLITE_NOMEM_BKPT;
+  }else{
+    rc = sqlite3_prepare_v2(pTab->db, zSql, -1, &pCsr->pStmt, 0);
+    sqlite3_free(zSql);
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = statNext(pCursor);
+  }
+  return rc;
+}
+
+static int statColumn(
+  sqlite3_vtab_cursor *pCursor, 
+  sqlite3_context *ctx, 
+  int i
+){
+  StatCursor *pCsr = (StatCursor *)pCursor;
+  switch( i ){
+    case 0:            /* name */
+      sqlite3_result_text(ctx, pCsr->zName, -1, SQLITE_TRANSIENT);
+      break;
+    case 1:            /* path */
+      sqlite3_result_text(ctx, pCsr->zPath, -1, SQLITE_TRANSIENT);
+      break;
+    case 2:            /* pageno */
+      sqlite3_result_int64(ctx, pCsr->iPageno);
+      break;
+    case 3:            /* pagetype */
+      sqlite3_result_text(ctx, pCsr->zPagetype, -1, SQLITE_STATIC);
+      break;
+    case 4:            /* ncell */
+      sqlite3_result_int(ctx, pCsr->nCell);
+      break;
+    case 5:            /* payload */
+      sqlite3_result_int(ctx, pCsr->nPayload);
+      break;
+    case 6:            /* unused */
+      sqlite3_result_int(ctx, pCsr->nUnused);
+      break;
+    case 7:            /* mx_payload */
+      sqlite3_result_int(ctx, pCsr->nMxPayload);
+      break;
+    case 8:            /* pgoffset */
+      sqlite3_result_int64(ctx, pCsr->iOffset);
+      break;
+    case 9:            /* pgsize */
+      sqlite3_result_int(ctx, pCsr->szPage);
+      break;
+    default: {          /* schema */
+      sqlite3 *db = sqlite3_context_db_handle(ctx);
+      int iDb = pCsr->iDb;
+      sqlite3_result_text(ctx, db->aDb[iDb].zDbSName, -1, SQLITE_STATIC);
+      break;
+    }
+  }
+  return SQLITE_OK;
+}
+
+static int statRowid(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
+  StatCursor *pCsr = (StatCursor *)pCursor;
+  *pRowid = pCsr->iPageno;
+  return SQLITE_OK;
+}
+
+/*
+** Invoke this routine to register the "dbstat" virtual table module
+*/
+SQLITE_PRIVATE int sqlite3DbstatRegister(sqlite3 *db){
+  static sqlite3_module dbstat_module = {
+    0,                            /* iVersion */
+    statConnect,                  /* xCreate */
+    statConnect,                  /* xConnect */
+    statBestIndex,                /* xBestIndex */
+    statDisconnect,               /* xDisconnect */
+    statDisconnect,               /* xDestroy */
+    statOpen,                     /* xOpen - open a cursor */
+    statClose,                    /* xClose - close a cursor */
+    statFilter,                   /* xFilter - configure scan constraints */
+    statNext,                     /* xNext - advance a cursor */
+    statEof,                      /* xEof - check for end of scan */
+    statColumn,                   /* xColumn - read data */
+    statRowid,                    /* xRowid - read data */
+    0,                            /* xUpdate */
+    0,                            /* xBegin */
+    0,                            /* xSync */
+    0,                            /* xCommit */
+    0,                            /* xRollback */
+    0,                            /* xFindMethod */
+    0,                            /* xRename */
+  };
+  return sqlite3_create_module(db, "dbstat", &dbstat_module, 0);
+}
+#elif defined(SQLITE_ENABLE_DBSTAT_VTAB)
+SQLITE_PRIVATE int sqlite3DbstatRegister(sqlite3 *db){ return SQLITE_OK; }
+#endif /* SQLITE_ENABLE_DBSTAT_VTAB */
+
+/************** End of dbstat.c **********************************************/
+/************** Begin file sqlite3session.c **********************************/
+
+#if defined(SQLITE_ENABLE_SESSION) && defined(SQLITE_ENABLE_PREUPDATE_HOOK)
+/* #include "sqlite3session.h" */
+/* #include <assert.h> */
+/* #include <string.h> */
+
+#ifndef SQLITE_AMALGAMATION
+/* # include "sqliteInt.h" */
+/* # include "vdbeInt.h" */
+#endif
+
+typedef struct SessionTable SessionTable;
+typedef struct SessionChange SessionChange;
+typedef struct SessionBuffer SessionBuffer;
+typedef struct SessionInput SessionInput;
+
+/*
+** Minimum chunk size used by streaming versions of functions.
+*/
+#ifndef SESSIONS_STRM_CHUNK_SIZE
+# ifdef SQLITE_TEST
+#   define SESSIONS_STRM_CHUNK_SIZE 64
+# else
+#   define SESSIONS_STRM_CHUNK_SIZE 1024
+# endif
+#endif
+
+typedef struct SessionHook SessionHook;
+struct SessionHook {
+  void *pCtx;
+  int (*xOld)(void*,int,sqlite3_value**);
+  int (*xNew)(void*,int,sqlite3_value**);
+  int (*xCount)(void*);
+  int (*xDepth)(void*);
+};
+
+/*
+** Session handle structure.
+*/
+struct sqlite3_session {
+  sqlite3 *db;                    /* Database handle session is attached to */
+  char *zDb;                      /* Name of database session is attached to */
+  int bEnable;                    /* True if currently recording */
+  int bIndirect;                  /* True if all changes are indirect */
+  int bAutoAttach;                /* True to auto-attach tables */
+  int rc;                         /* Non-zero if an error has occurred */
+  void *pFilterCtx;               /* First argument to pass to xTableFilter */
+  int (*xTableFilter)(void *pCtx, const char *zTab);
+  sqlite3_session *pNext;         /* Next session object on same db. */
+  SessionTable *pTable;           /* List of attached tables */
+  SessionHook hook;               /* APIs to grab new and old data with */
+};
+
+/*
+** Instances of this structure are used to build strings or binary records.
+*/
+struct SessionBuffer {
+  u8 *aBuf;                       /* Pointer to changeset buffer */
+  int nBuf;                       /* Size of buffer aBuf */
+  int nAlloc;                     /* Size of allocation containing aBuf */
+};
+
+/*
+** An object of this type is used internally as an abstraction for 
+** input data. Input data may be supplied either as a single large buffer
+** (e.g. sqlite3changeset_start()) or using a stream function (e.g.
+**  sqlite3changeset_start_strm()).
+*/
+struct SessionInput {
+  int bNoDiscard;                 /* If true, discard no data */
+  int iCurrent;                   /* Offset in aData[] of current change */
+  int iNext;                      /* Offset in aData[] of next change */
+  u8 *aData;                      /* Pointer to buffer containing changeset */
+  int nData;                      /* Number of bytes in aData */
+
+  SessionBuffer buf;              /* Current read buffer */
+  int (*xInput)(void*, void*, int*);        /* Input stream call (or NULL) */
+  void *pIn;                                /* First argument to xInput */
+  int bEof;                       /* Set to true after xInput finished */
+};
+
+/*
+** Structure for changeset iterators.
+*/
+struct sqlite3_changeset_iter {
+  SessionInput in;                /* Input buffer or stream */
+  SessionBuffer tblhdr;           /* Buffer to hold apValue/zTab/abPK/ */
+  int bPatchset;                  /* True if this is a patchset */
+  int rc;                         /* Iterator error code */
+  sqlite3_stmt *pConflict;        /* Points to conflicting row, if any */
+  char *zTab;                     /* Current table */
+  int nCol;                       /* Number of columns in zTab */
+  int op;                         /* Current operation */
+  int bIndirect;                  /* True if current change was indirect */
+  u8 *abPK;                       /* Primary key array */
+  sqlite3_value **apValue;        /* old.* and new.* values */
+};
+
+/*
+** Each session object maintains a set of the following structures, one
+** for each table the session object is monitoring. The structures are
+** stored in a linked list starting at sqlite3_session.pTable.
+**
+** The keys of the SessionTable.aChange[] hash table are all rows that have
+** been modified in any way since the session object was attached to the
+** table.
+**
+** The data associated with each hash-table entry is a structure containing
+** a subset of the initial values that the modified row contained at the
+** start of the session. Or no initial values if the row was inserted.
+*/
+struct SessionTable {
+  SessionTable *pNext;
+  char *zName;                    /* Local name of table */
+  int nCol;                       /* Number of columns in table zName */
+  const char **azCol;             /* Column names */
+  u8 *abPK;                       /* Array of primary key flags */
+  int nEntry;                     /* Total number of entries in hash table */
+  int nChange;                    /* Size of apChange[] array */
+  SessionChange **apChange;       /* Hash table buckets */
+};
+
+/* 
+** RECORD FORMAT:
+**
+** The following record format is similar to (but not compatible with) that 
+** used in SQLite database files. This format is used as part of the 
+** change-set binary format, and so must be architecture independent.
+**
+** Unlike the SQLite database record format, each field is self-contained -
+** there is no separation of header and data. Each field begins with a
+** single byte describing its type, as follows:
+**
+**       0x00: Undefined value.
+**       0x01: Integer value.
+**       0x02: Real value.
+**       0x03: Text value.
+**       0x04: Blob value.
+**       0x05: SQL NULL value.
+**
+** Note that the above match the definitions of SQLITE_INTEGER, SQLITE_TEXT
+** and so on in sqlite3.h. For undefined and NULL values, the field consists
+** only of the single type byte. For other types of values, the type byte
+** is followed by:
+**
+**   Text values:
+**     A varint containing the number of bytes in the value (encoded using
+**     UTF-8). Followed by a buffer containing the UTF-8 representation
+**     of the text value. There is no nul terminator.
+**
+**   Blob values:
+**     A varint containing the number of bytes in the value, followed by
+**     a buffer containing the value itself.
+**
+**   Integer values:
+**     An 8-byte big-endian integer value.
+**
+**   Real values:
+**     An 8-byte big-endian IEEE 754-2008 real value.
+**
+** Varint values are encoded in the same way as varints in the SQLite 
+** record format.
+**
+** CHANGESET FORMAT:
+**
+** A changeset is a collection of DELETE, UPDATE and INSERT operations on
+** one or more tables. Operations on a single table are grouped together,
+** but may occur in any order (i.e. deletes, updates and inserts are all
+** mixed together).
+**
+** Each group of changes begins with a table header:
+**
+**   1 byte: Constant 0x54 (capital 'T')
+**   Varint: Number of columns in the table.
+**   nCol bytes: 0x01 for PK columns, 0x00 otherwise.
+**   N bytes: Unqualified table name (encoded using UTF-8). Nul-terminated.
+**
+** Followed by one or more changes to the table.
+**
+**   1 byte: Either SQLITE_INSERT (0x12), UPDATE (0x17) or DELETE (0x09).
+**   1 byte: The "indirect-change" flag.
+**   old.* record: (delete and update only)
+**   new.* record: (insert and update only)
+**
+** The "old.*" and "new.*" records, if present, are N field records in the
+** format described above under "RECORD FORMAT", where N is the number of
+** columns in the table. The i'th field of each record is associated with
+** the i'th column of the table, counting from left to right in the order
+** in which columns were declared in the CREATE TABLE statement.
+**
+** The new.* record that is part of each INSERT change contains the values
+** that make up the new row. Similarly, the old.* record that is part of each
+** DELETE change contains the values that made up the row that was deleted 
+** from the database. In the changeset format, the records that are part
+** of INSERT or DELETE changes never contain any undefined (type byte 0x00)
+** fields.
+**
+** Within the old.* record associated with an UPDATE change, all fields
+** associated with table columns that are not PRIMARY KEY columns and are
+** not modified by the UPDATE change are set to "undefined". Other fields
+** are set to the values that made up the row before the UPDATE that the
+** change records took place. Within the new.* record, fields associated 
+** with table columns modified by the UPDATE change contain the new 
+** values. Fields associated with table columns that are not modified
+** are set to "undefined".
+**
+** PATCHSET FORMAT:
+**
+** A patchset is also a collection of changes. It is similar to a changeset,
+** but leaves undefined those fields that are not useful if no conflict
+** resolution is required when applying the changeset.
+**
+** Each group of changes begins with a table header:
+**
+**   1 byte: Constant 0x50 (capital 'P')
+**   Varint: Number of columns in the table.
+**   nCol bytes: 0x01 for PK columns, 0x00 otherwise.
+**   N bytes: Unqualified table name (encoded using UTF-8). Nul-terminated.
+**
+** Followed by one or more changes to the table.
+**
+**   1 byte: Either SQLITE_INSERT (0x12), UPDATE (0x17) or DELETE (0x09).
+**   1 byte: The "indirect-change" flag.
+**   single record: (PK fields for DELETE, PK and modified fields for UPDATE,
+**                   full record for INSERT).
+**
+** As in the changeset format, each field of the single record that is part
+** of a patchset change is associated with the correspondingly positioned
+** table column, counting from left to right within the CREATE TABLE 
+** statement.
+**
+** For a DELETE change, all fields within the record except those associated
+** with PRIMARY KEY columns are set to "undefined". The PRIMARY KEY fields
+** contain the values identifying the row to delete.
+**
+** For an UPDATE change, all fields except those associated with PRIMARY KEY
+** columns and columns that are modified by the UPDATE are set to "undefined".
+** PRIMARY KEY fields contain the values identifying the table row to update,
+** and fields associated with modified columns contain the new column values.
+**
+** The records associated with INSERT changes are in the same format as for
+** changesets. It is not possible for a record associated with an INSERT
+** change to contain a field set to "undefined".
+*/
+
+/*
+** For each row modified during a session, there exists a single instance of
+** this structure stored in a SessionTable.aChange[] hash table.
+*/
+struct SessionChange {
+  int op;                         /* One of UPDATE, DELETE, INSERT */
+  int bIndirect;                  /* True if this change is "indirect" */
+  int nRecord;                    /* Number of bytes in buffer aRecord[] */
+  u8 *aRecord;                    /* Buffer containing old.* record */
+  SessionChange *pNext;           /* For hash-table collisions */
+};
+
+/*
+** Write a varint with value iVal into the buffer at aBuf. Return the 
+** number of bytes written.
+*/
+static int sessionVarintPut(u8 *aBuf, int iVal){
+  return putVarint32(aBuf, iVal);
+}
+
+/*
+** Return the number of bytes required to store value iVal as a varint.
+*/
+static int sessionVarintLen(int iVal){
+  return sqlite3VarintLen(iVal);
+}
+
+/*
+** Read a varint value from aBuf[] into *piVal. Return the number of 
+** bytes read.
+*/
+static int sessionVarintGet(u8 *aBuf, int *piVal){
+  return getVarint32(aBuf, *piVal);
+}
+
+/* Load an unaligned and unsigned 32-bit integer */
+#define SESSION_UINT32(x) (((u32)(x)[0]<<24)|((x)[1]<<16)|((x)[2]<<8)|(x)[3])
+
+/*
+** Read a 64-bit big-endian integer value from buffer aRec[]. Return
+** the value read.
+*/
+static sqlite3_int64 sessionGetI64(u8 *aRec){
+  u64 x = SESSION_UINT32(aRec);
+  u32 y = SESSION_UINT32(aRec+4);
+  x = (x<<32) + y;
+  return (sqlite3_int64)x;
+}
+
+/*
+** Write a 64-bit big-endian integer value to the buffer aBuf[].
+*/
+static void sessionPutI64(u8 *aBuf, sqlite3_int64 i){
+  aBuf[0] = (i>>56) & 0xFF;
+  aBuf[1] = (i>>48) & 0xFF;
+  aBuf[2] = (i>>40) & 0xFF;
+  aBuf[3] = (i>>32) & 0xFF;
+  aBuf[4] = (i>>24) & 0xFF;
+  aBuf[5] = (i>>16) & 0xFF;
+  aBuf[6] = (i>> 8) & 0xFF;
+  aBuf[7] = (i>> 0) & 0xFF;
+}
+
+/*
+** This function is used to serialize the contents of value pValue (see
+** comment titled "RECORD FORMAT" above).
+**
+** If it is non-NULL, the serialized form of the value is written to 
+** buffer aBuf. *pnWrite is set to the number of bytes written before
+** returning. Or, if aBuf is NULL, the only thing this function does is
+** set *pnWrite.
+**
+** If no error occurs, SQLITE_OK is returned. Or, if an OOM error occurs
+** within a call to sqlite3_value_text() (may fail if the db is utf-16)) 
+** SQLITE_NOMEM is returned.
+*/
+static int sessionSerializeValue(
+  u8 *aBuf,                       /* If non-NULL, write serialized value here */
+  sqlite3_value *pValue,          /* Value to serialize */
+  int *pnWrite                    /* IN/OUT: Increment by bytes written */
+){
+  int nByte;                      /* Size of serialized value in bytes */
+
+  if( pValue ){
+    int eType;                    /* Value type (SQLITE_NULL, TEXT etc.) */
+  
+    eType = sqlite3_value_type(pValue);
+    if( aBuf ) aBuf[0] = eType;
+  
+    switch( eType ){
+      case SQLITE_NULL: 
+        nByte = 1;
+        break;
+  
+      case SQLITE_INTEGER: 
+      case SQLITE_FLOAT:
+        if( aBuf ){
+          /* TODO: SQLite does something special to deal with mixed-endian
+          ** floating point values (e.g. ARM7). This code probably should
+          ** too.  */
+          u64 i;
+          if( eType==SQLITE_INTEGER ){
+            i = (u64)sqlite3_value_int64(pValue);
+          }else{
+            double r;
+            assert( sizeof(double)==8 && sizeof(u64)==8 );
+            r = sqlite3_value_double(pValue);
+            memcpy(&i, &r, 8);
+          }
+          sessionPutI64(&aBuf[1], i);
+        }
+        nByte = 9; 
+        break;
+  
+      default: {
+        u8 *z;
+        int n;
+        int nVarint;
+  
+        assert( eType==SQLITE_TEXT || eType==SQLITE_BLOB );
+        if( eType==SQLITE_TEXT ){
+          z = (u8 *)sqlite3_value_text(pValue);
+        }else{
+          z = (u8 *)sqlite3_value_blob(pValue);
+        }
+        n = sqlite3_value_bytes(pValue);
+        if( z==0 && (eType!=SQLITE_BLOB || n>0) ) return SQLITE_NOMEM;
+        nVarint = sessionVarintLen(n);
+  
+        if( aBuf ){
+          sessionVarintPut(&aBuf[1], n);
+          memcpy(&aBuf[nVarint + 1], eType==SQLITE_TEXT ? 
+              sqlite3_value_text(pValue) : sqlite3_value_blob(pValue), n
+          );
+        }
+  
+        nByte = 1 + nVarint + n;
+        break;
+      }
+    }
+  }else{
+    nByte = 1;
+    if( aBuf ) aBuf[0] = '\0';
+  }
+
+  if( pnWrite ) *pnWrite += nByte;
+  return SQLITE_OK;
+}
+
+
+/*
+** This macro is used to calculate hash key values for data structures. In
+** order to use this macro, the entire data structure must be represented
+** as a series of unsigned integers. In order to calculate a hash-key value
+** for a data structure represented as three such integers, the macro may
+** then be used as follows:
+**
+**    int hash_key_value;
+**    hash_key_value = HASH_APPEND(0, <value 1>);
+**    hash_key_value = HASH_APPEND(hash_key_value, <value 2>);
+**    hash_key_value = HASH_APPEND(hash_key_value, <value 3>);
+**
+** In practice, the data structures this macro is used for are the primary
+** key values of modified rows.
+*/
+#define HASH_APPEND(hash, add) ((hash) << 3) ^ (hash) ^ (unsigned int)(add)
+
+/*
+** Append the hash of the 64-bit integer passed as the second argument to the
+** hash-key value passed as the first. Return the new hash-key value.
+*/
+static unsigned int sessionHashAppendI64(unsigned int h, i64 i){
+  h = HASH_APPEND(h, i & 0xFFFFFFFF);
+  return HASH_APPEND(h, (i>>32)&0xFFFFFFFF);
+}
+
+/*
+** Append the hash of the blob passed via the second and third arguments to 
+** the hash-key value passed as the first. Return the new hash-key value.
+*/
+static unsigned int sessionHashAppendBlob(unsigned int h, int n, const u8 *z){
+  int i;
+  for(i=0; i<n; i++) h = HASH_APPEND(h, z[i]);
+  return h;
+}
+
+/*
+** Append the hash of the data type passed as the second argument to the
+** hash-key value passed as the first. Return the new hash-key value.
+*/
+static unsigned int sessionHashAppendType(unsigned int h, int eType){
+  return HASH_APPEND(h, eType);
+}
+
+/*
+** This function may only be called from within a pre-update callback.
+** It calculates a hash based on the primary key values of the old.* or 
+** new.* row currently available and, assuming no error occurs, writes it to
+** *piHash before returning. If the primary key contains one or more NULL
+** values, *pbNullPK is set to true before returning.
+**
+** If an error occurs, an SQLite error code is returned and the final values
+** of *piHash asn *pbNullPK are undefined. Otherwise, SQLITE_OK is returned
+** and the output variables are set as described above.
+*/
+static int sessionPreupdateHash(
+  sqlite3_session *pSession,      /* Session object that owns pTab */
+  SessionTable *pTab,             /* Session table handle */
+  int bNew,                       /* True to hash the new.* PK */
+  int *piHash,                    /* OUT: Hash value */
+  int *pbNullPK                   /* OUT: True if there are NULL values in PK */
+){
+  unsigned int h = 0;             /* Hash value to return */
+  int i;                          /* Used to iterate through columns */
+
+  assert( *pbNullPK==0 );
+  assert( pTab->nCol==pSession->hook.xCount(pSession->hook.pCtx) );
+  for(i=0; i<pTab->nCol; i++){
+    if( pTab->abPK[i] ){
+      int rc;
+      int eType;
+      sqlite3_value *pVal;
+
+      if( bNew ){
+        rc = pSession->hook.xNew(pSession->hook.pCtx, i, &pVal);
+      }else{
+        rc = pSession->hook.xOld(pSession->hook.pCtx, i, &pVal);
+      }
+      if( rc!=SQLITE_OK ) return rc;
+
+      eType = sqlite3_value_type(pVal);
+      h = sessionHashAppendType(h, eType);
+      if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
+        i64 iVal;
+        if( eType==SQLITE_INTEGER ){
+          iVal = sqlite3_value_int64(pVal);
+        }else{
+          double rVal = sqlite3_value_double(pVal);
+          assert( sizeof(iVal)==8 && sizeof(rVal)==8 );
+          memcpy(&iVal, &rVal, 8);
+        }
+        h = sessionHashAppendI64(h, iVal);
+      }else if( eType==SQLITE_TEXT || eType==SQLITE_BLOB ){
+        const u8 *z;
+        int n;
+        if( eType==SQLITE_TEXT ){
+          z = (const u8 *)sqlite3_value_text(pVal);
+        }else{
+          z = (const u8 *)sqlite3_value_blob(pVal);
+        }
+        n = sqlite3_value_bytes(pVal);
+        if( !z && (eType!=SQLITE_BLOB || n>0) ) return SQLITE_NOMEM;
+        h = sessionHashAppendBlob(h, n, z);
+      }else{
+        assert( eType==SQLITE_NULL );
+        *pbNullPK = 1;
+      }
+    }
+  }
+
+  *piHash = (h % pTab->nChange);
+  return SQLITE_OK;
+}
+
+/*
+** The buffer that the argument points to contains a serialized SQL value.
+** Return the number of bytes of space occupied by the value (including
+** the type byte).
+*/
+static int sessionSerialLen(u8 *a){
+  int e = *a;
+  int n;
+  if( e==0 ) return 1;
+  if( e==SQLITE_NULL ) return 1;
+  if( e==SQLITE_INTEGER || e==SQLITE_FLOAT ) return 9;
+  return sessionVarintGet(&a[1], &n) + 1 + n;
+}
+
+/*
+** Based on the primary key values stored in change aRecord, calculate a
+** hash key. Assume the has table has nBucket buckets. The hash keys
+** calculated by this function are compatible with those calculated by
+** sessionPreupdateHash().
+**
+** The bPkOnly argument is non-zero if the record at aRecord[] is from
+** a patchset DELETE. In this case the non-PK fields are omitted entirely.
+*/
+static unsigned int sessionChangeHash(
+  SessionTable *pTab,             /* Table handle */
+  int bPkOnly,                    /* Record consists of PK fields only */
+  u8 *aRecord,                    /* Change record */
+  int nBucket                     /* Assume this many buckets in hash table */
+){
+  unsigned int h = 0;             /* Value to return */
+  int i;                          /* Used to iterate through columns */
+  u8 *a = aRecord;                /* Used to iterate through change record */
+
+  for(i=0; i<pTab->nCol; i++){
+    int eType = *a;
+    int isPK = pTab->abPK[i];
+    if( bPkOnly && isPK==0 ) continue;
+
+    /* It is not possible for eType to be SQLITE_NULL here. The session 
+    ** module does not record changes for rows with NULL values stored in
+    ** primary key columns. */
+    assert( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT 
+         || eType==SQLITE_TEXT || eType==SQLITE_BLOB 
+         || eType==SQLITE_NULL || eType==0 
+    );
+    assert( !isPK || (eType!=0 && eType!=SQLITE_NULL) );
+
+    if( isPK ){
+      a++;
+      h = sessionHashAppendType(h, eType);
+      if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
+        h = sessionHashAppendI64(h, sessionGetI64(a));
+        a += 8;
+      }else{
+        int n; 
+        a += sessionVarintGet(a, &n);
+        h = sessionHashAppendBlob(h, n, a);
+        a += n;
+      }
+    }else{
+      a += sessionSerialLen(a);
+    }
+  }
+  return (h % nBucket);
+}
+
+/*
+** Arguments aLeft and aRight are pointers to change records for table pTab.
+** This function returns true if the two records apply to the same row (i.e.
+** have the same values stored in the primary key columns), or false 
+** otherwise.
+*/
+static int sessionChangeEqual(
+  SessionTable *pTab,             /* Table used for PK definition */
+  int bLeftPkOnly,                /* True if aLeft[] contains PK fields only */
+  u8 *aLeft,                      /* Change record */
+  int bRightPkOnly,               /* True if aRight[] contains PK fields only */
+  u8 *aRight                      /* Change record */
+){
+  u8 *a1 = aLeft;                 /* Cursor to iterate through aLeft */
+  u8 *a2 = aRight;                /* Cursor to iterate through aRight */
+  int iCol;                       /* Used to iterate through table columns */
+
+  for(iCol=0; iCol<pTab->nCol; iCol++){
+    if( pTab->abPK[iCol] ){
+      int n1 = sessionSerialLen(a1);
+      int n2 = sessionSerialLen(a2);
+
+      if( pTab->abPK[iCol] && (n1!=n2 || memcmp(a1, a2, n1)) ){
+        return 0;
+      }
+      a1 += n1;
+      a2 += n2;
+    }else{
+      if( bLeftPkOnly==0 ) a1 += sessionSerialLen(a1);
+      if( bRightPkOnly==0 ) a2 += sessionSerialLen(a2);
+    }
+  }
+
+  return 1;
+}
+
+/*
+** Arguments aLeft and aRight both point to buffers containing change
+** records with nCol columns. This function "merges" the two records into
+** a single records which is written to the buffer at *paOut. *paOut is
+** then set to point to one byte after the last byte written before 
+** returning.
+**
+** The merging of records is done as follows: For each column, if the 
+** aRight record contains a value for the column, copy the value from
+** their. Otherwise, if aLeft contains a value, copy it. If neither
+** record contains a value for a given column, then neither does the
+** output record.
+*/
+static void sessionMergeRecord(
+  u8 **paOut, 
+  int nCol,
+  u8 *aLeft,
+  u8 *aRight
+){
+  u8 *a1 = aLeft;                 /* Cursor used to iterate through aLeft */
+  u8 *a2 = aRight;                /* Cursor used to iterate through aRight */
+  u8 *aOut = *paOut;              /* Output cursor */
+  int iCol;                       /* Used to iterate from 0 to nCol */
+
+  for(iCol=0; iCol<nCol; iCol++){
+    int n1 = sessionSerialLen(a1);
+    int n2 = sessionSerialLen(a2);
+    if( *a2 ){
+      memcpy(aOut, a2, n2);
+      aOut += n2;
+    }else{
+      memcpy(aOut, a1, n1);
+      aOut += n1;
+    }
+    a1 += n1;
+    a2 += n2;
+  }
+
+  *paOut = aOut;
+}
+
+/*
+** This is a helper function used by sessionMergeUpdate().
+**
+** When this function is called, both *paOne and *paTwo point to a value 
+** within a change record. Before it returns, both have been advanced so 
+** as to point to the next value in the record.
+**
+** If, when this function is called, *paTwo points to a valid value (i.e.
+** *paTwo[0] is not 0x00 - the "no value" placeholder), a copy of the *paTwo
+** pointer is returned and *pnVal is set to the number of bytes in the 
+** serialized value. Otherwise, a copy of *paOne is returned and *pnVal
+** set to the number of bytes in the value at *paOne. If *paOne points
+** to the "no value" placeholder, *pnVal is set to 1. In other words:
+**
+**   if( *paTwo is valid ) return *paTwo;
+**   return *paOne;
+**
+*/
+static u8 *sessionMergeValue(
+  u8 **paOne,                     /* IN/OUT: Left-hand buffer pointer */
+  u8 **paTwo,                     /* IN/OUT: Right-hand buffer pointer */
+  int *pnVal                      /* OUT: Bytes in returned value */
+){
+  u8 *a1 = *paOne;
+  u8 *a2 = *paTwo;
+  u8 *pRet = 0;
+  int n1;
+
+  assert( a1 );
+  if( a2 ){
+    int n2 = sessionSerialLen(a2);
+    if( *a2 ){
+      *pnVal = n2;
+      pRet = a2;
+    }
+    *paTwo = &a2[n2];
+  }
+
+  n1 = sessionSerialLen(a1);
+  if( pRet==0 ){
+    *pnVal = n1;
+    pRet = a1;
+  }
+  *paOne = &a1[n1];
+
+  return pRet;
+}
+
+/*
+** This function is used by changeset_concat() to merge two UPDATE changes
+** on the same row.
+*/
+static int sessionMergeUpdate(
+  u8 **paOut,                     /* IN/OUT: Pointer to output buffer */
+  SessionTable *pTab,             /* Table change pertains to */
+  int bPatchset,                  /* True if records are patchset records */
+  u8 *aOldRecord1,                /* old.* record for first change */
+  u8 *aOldRecord2,                /* old.* record for second change */
+  u8 *aNewRecord1,                /* new.* record for first change */
+  u8 *aNewRecord2                 /* new.* record for second change */
+){
+  u8 *aOld1 = aOldRecord1;
+  u8 *aOld2 = aOldRecord2;
+  u8 *aNew1 = aNewRecord1;
+  u8 *aNew2 = aNewRecord2;
+
+  u8 *aOut = *paOut;
+  int i;
+
+  if( bPatchset==0 ){
+    int bRequired = 0;
+
+    assert( aOldRecord1 && aNewRecord1 );
+
+    /* Write the old.* vector first. */
+    for(i=0; i<pTab->nCol; i++){
+      int nOld;
+      u8 *aOld;
+      int nNew;
+      u8 *aNew;
+
+      aOld = sessionMergeValue(&aOld1, &aOld2, &nOld);
+      aNew = sessionMergeValue(&aNew1, &aNew2, &nNew);
+      if( pTab->abPK[i] || nOld!=nNew || memcmp(aOld, aNew, nNew) ){
+        if( pTab->abPK[i]==0 ) bRequired = 1;
+        memcpy(aOut, aOld, nOld);
+        aOut += nOld;
+      }else{
+        *(aOut++) = '\0';
+      }
+    }
+
+    if( !bRequired ) return 0;
+  }
+
+  /* Write the new.* vector */
+  aOld1 = aOldRecord1;
+  aOld2 = aOldRecord2;
+  aNew1 = aNewRecord1;
+  aNew2 = aNewRecord2;
+  for(i=0; i<pTab->nCol; i++){
+    int nOld;
+    u8 *aOld;
+    int nNew;
+    u8 *aNew;
+
+    aOld = sessionMergeValue(&aOld1, &aOld2, &nOld);
+    aNew = sessionMergeValue(&aNew1, &aNew2, &nNew);
+    if( bPatchset==0 
+     && (pTab->abPK[i] || (nOld==nNew && 0==memcmp(aOld, aNew, nNew))) 
+    ){
+      *(aOut++) = '\0';
+    }else{
+      memcpy(aOut, aNew, nNew);
+      aOut += nNew;
+    }
+  }
+
+  *paOut = aOut;
+  return 1;
+}
+
+/*
+** This function is only called from within a pre-update-hook callback.
+** It determines if the current pre-update-hook change affects the same row
+** as the change stored in argument pChange. If so, it returns true. Otherwise
+** if the pre-update-hook does not affect the same row as pChange, it returns
+** false.
+*/
+static int sessionPreupdateEqual(
+  sqlite3_session *pSession,      /* Session object that owns SessionTable */
+  SessionTable *pTab,             /* Table associated with change */
+  SessionChange *pChange,         /* Change to compare to */
+  int op                          /* Current pre-update operation */
+){
+  int iCol;                       /* Used to iterate through columns */
+  u8 *a = pChange->aRecord;       /* Cursor used to scan change record */
+
+  assert( op==SQLITE_INSERT || op==SQLITE_UPDATE || op==SQLITE_DELETE );
+  for(iCol=0; iCol<pTab->nCol; iCol++){
+    if( !pTab->abPK[iCol] ){
+      a += sessionSerialLen(a);
+    }else{
+      sqlite3_value *pVal;        /* Value returned by preupdate_new/old */
+      int rc;                     /* Error code from preupdate_new/old */
+      int eType = *a++;           /* Type of value from change record */
+
+      /* The following calls to preupdate_new() and preupdate_old() can not
+      ** fail. This is because they cache their return values, and by the
+      ** time control flows to here they have already been called once from
+      ** within sessionPreupdateHash(). The first two asserts below verify
+      ** this (that the method has already been called). */
+      if( op==SQLITE_INSERT ){
+        /* assert( db->pPreUpdate->pNewUnpacked || db->pPreUpdate->aNew ); */
+        rc = pSession->hook.xNew(pSession->hook.pCtx, iCol, &pVal);
+      }else{
+        /* assert( db->pPreUpdate->pUnpacked ); */
+        rc = pSession->hook.xOld(pSession->hook.pCtx, iCol, &pVal);
+      }
+      assert( rc==SQLITE_OK );
+      if( sqlite3_value_type(pVal)!=eType ) return 0;
+
+      /* A SessionChange object never has a NULL value in a PK column */
+      assert( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT
+           || eType==SQLITE_BLOB    || eType==SQLITE_TEXT
+      );
+
+      if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
+        i64 iVal = sessionGetI64(a);
+        a += 8;
+        if( eType==SQLITE_INTEGER ){
+          if( sqlite3_value_int64(pVal)!=iVal ) return 0;
+        }else{
+          double rVal;
+          assert( sizeof(iVal)==8 && sizeof(rVal)==8 );
+          memcpy(&rVal, &iVal, 8);
+          if( sqlite3_value_double(pVal)!=rVal ) return 0;
+        }
+      }else{
+        int n;
+        const u8 *z;
+        a += sessionVarintGet(a, &n);
+        if( sqlite3_value_bytes(pVal)!=n ) return 0;
+        if( eType==SQLITE_TEXT ){
+          z = sqlite3_value_text(pVal);
+        }else{
+          z = sqlite3_value_blob(pVal);
+        }
+        if( memcmp(a, z, n) ) return 0;
+        a += n;
+        break;
+      }
+    }
+  }
+
+  return 1;
+}
+
+/*
+** If required, grow the hash table used to store changes on table pTab 
+** (part of the session pSession). If a fatal OOM error occurs, set the
+** session object to failed and return SQLITE_ERROR. Otherwise, return
+** SQLITE_OK.
+**
+** It is possible that a non-fatal OOM error occurs in this function. In
+** that case the hash-table does not grow, but SQLITE_OK is returned anyway.
+** Growing the hash table in this case is a performance optimization only,
+** it is not required for correct operation.
+*/
+static int sessionGrowHash(int bPatchset, SessionTable *pTab){
+  if( pTab->nChange==0 || pTab->nEntry>=(pTab->nChange/2) ){
+    int i;
+    SessionChange **apNew;
+    int nNew = (pTab->nChange ? pTab->nChange : 128) * 2;
+
+    apNew = (SessionChange **)sqlite3_malloc(sizeof(SessionChange *) * nNew);
+    if( apNew==0 ){
+      if( pTab->nChange==0 ){
+        return SQLITE_ERROR;
+      }
+      return SQLITE_OK;
+    }
+    memset(apNew, 0, sizeof(SessionChange *) * nNew);
+
+    for(i=0; i<pTab->nChange; i++){
+      SessionChange *p;
+      SessionChange *pNext;
+      for(p=pTab->apChange[i]; p; p=pNext){
+        int bPkOnly = (p->op==SQLITE_DELETE && bPatchset);
+        int iHash = sessionChangeHash(pTab, bPkOnly, p->aRecord, nNew);
+        pNext = p->pNext;
+        p->pNext = apNew[iHash];
+        apNew[iHash] = p;
+      }
+    }
+
+    sqlite3_free(pTab->apChange);
+    pTab->nChange = nNew;
+    pTab->apChange = apNew;
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** This function queries the database for the names of the columns of table
+** zThis, in schema zDb. It is expected that the table has nCol columns. If
+** not, SQLITE_SCHEMA is returned and none of the output variables are
+** populated.
+**
+** Otherwise, if they are not NULL, variable *pnCol is set to the number
+** of columns in the database table and variable *pzTab is set to point to a
+** nul-terminated copy of the table name. *pazCol (if not NULL) is set to
+** point to an array of pointers to column names. And *pabPK (again, if not
+** NULL) is set to point to an array of booleans - true if the corresponding
+** column is part of the primary key.
+**
+** For example, if the table is declared as:
+**
+**     CREATE TABLE tbl1(w, x, y, z, PRIMARY KEY(w, z));
+**
+** Then the four output variables are populated as follows:
+**
+**     *pnCol  = 4
+**     *pzTab  = "tbl1"
+**     *pazCol = {"w", "x", "y", "z"}
+**     *pabPK  = {1, 0, 0, 1}
+**
+** All returned buffers are part of the same single allocation, which must
+** be freed using sqlite3_free() by the caller. If pazCol was not NULL, then
+** pointer *pazCol should be freed to release all memory. Otherwise, pointer
+** *pabPK. It is illegal for both pazCol and pabPK to be NULL.
+*/
+static int sessionTableInfo(
+  sqlite3 *db,                    /* Database connection */
+  const char *zDb,                /* Name of attached database (e.g. "main") */
+  const char *zThis,              /* Table name */
+  int *pnCol,                     /* OUT: number of columns */
+  const char **pzTab,             /* OUT: Copy of zThis */
+  const char ***pazCol,           /* OUT: Array of column names for table */
+  u8 **pabPK                      /* OUT: Array of booleans - true for PK col */
+){
+  char *zPragma;
+  sqlite3_stmt *pStmt;
+  int rc;
+  int nByte;
+  int nDbCol = 0;
+  int nThis;
+  int i;
+  u8 *pAlloc = 0;
+  char **azCol = 0;
+  u8 *abPK = 0;
+
+  assert( pazCol && pabPK );
+
+  nThis = sqlite3Strlen30(zThis);
+  zPragma = sqlite3_mprintf("PRAGMA '%q'.table_info('%q')", zDb, zThis);
+  if( !zPragma ) return SQLITE_NOMEM;
+
+  rc = sqlite3_prepare_v2(db, zPragma, -1, &pStmt, 0);
+  sqlite3_free(zPragma);
+  if( rc!=SQLITE_OK ) return rc;
+
+  nByte = nThis + 1;
+  while( SQLITE_ROW==sqlite3_step(pStmt) ){
+    nByte += sqlite3_column_bytes(pStmt, 1);
+    nDbCol++;
+  }
+  rc = sqlite3_reset(pStmt);
+
+  if( rc==SQLITE_OK ){
+    nByte += nDbCol * (sizeof(const char *) + sizeof(u8) + 1);
+    pAlloc = sqlite3_malloc(nByte);
+    if( pAlloc==0 ){
+      rc = SQLITE_NOMEM;
+    }
+  }
+  if( rc==SQLITE_OK ){
+    azCol = (char **)pAlloc;
+    pAlloc = (u8 *)&azCol[nDbCol];
+    abPK = (u8 *)pAlloc;
+    pAlloc = &abPK[nDbCol];
+    if( pzTab ){
+      memcpy(pAlloc, zThis, nThis+1);
+      *pzTab = (char *)pAlloc;
+      pAlloc += nThis+1;
+    }
+  
+    i = 0;
+    while( SQLITE_ROW==sqlite3_step(pStmt) ){
+      int nName = sqlite3_column_bytes(pStmt, 1);
+      const unsigned char *zName = sqlite3_column_text(pStmt, 1);
+      if( zName==0 ) break;
+      memcpy(pAlloc, zName, nName+1);
+      azCol[i] = (char *)pAlloc;
+      pAlloc += nName+1;
+      abPK[i] = sqlite3_column_int(pStmt, 5);
+      i++;
+    }
+    rc = sqlite3_reset(pStmt);
+  
+  }
+
+  /* If successful, populate the output variables. Otherwise, zero them and
+  ** free any allocation made. An error code will be returned in this case.
+  */
+  if( rc==SQLITE_OK ){
+    *pazCol = (const char **)azCol;
+    *pabPK = abPK;
+    *pnCol = nDbCol;
+  }else{
+    *pazCol = 0;
+    *pabPK = 0;
+    *pnCol = 0;
+    if( pzTab ) *pzTab = 0;
+    sqlite3_free(azCol);
+  }
+  sqlite3_finalize(pStmt);
+  return rc;
+}
+
+/*
+** This function is only called from within a pre-update handler for a
+** write to table pTab, part of session pSession. If this is the first
+** write to this table, initalize the SessionTable.nCol, azCol[] and
+** abPK[] arrays accordingly.
+**
+** If an error occurs, an error code is stored in sqlite3_session.rc and
+** non-zero returned. Or, if no error occurs but the table has no primary
+** key, sqlite3_session.rc is left set to SQLITE_OK and non-zero returned to
+** indicate that updates on this table should be ignored. SessionTable.abPK 
+** is set to NULL in this case.
+*/
+static int sessionInitTable(sqlite3_session *pSession, SessionTable *pTab){
+  if( pTab->nCol==0 ){
+    u8 *abPK;
+    assert( pTab->azCol==0 || pTab->abPK==0 );
+    pSession->rc = sessionTableInfo(pSession->db, pSession->zDb, 
+        pTab->zName, &pTab->nCol, 0, &pTab->azCol, &abPK
+    );
+    if( pSession->rc==SQLITE_OK ){
+      int i;
+      for(i=0; i<pTab->nCol; i++){
+        if( abPK[i] ){
+          pTab->abPK = abPK;
+          break;
+        }
+      }
+    }
+  }
+  return (pSession->rc || pTab->abPK==0);
+}
+
+/*
+** This function is only called from with a pre-update-hook reporting a 
+** change on table pTab (attached to session pSession). The type of change
+** (UPDATE, INSERT, DELETE) is specified by the first argument.
+**
+** Unless one is already present or an error occurs, an entry is added
+** to the changed-rows hash table associated with table pTab.
+*/
+static void sessionPreupdateOneChange(
+  int op,                         /* One of SQLITE_UPDATE, INSERT, DELETE */
+  sqlite3_session *pSession,      /* Session object pTab is attached to */
+  SessionTable *pTab              /* Table that change applies to */
+){
+  int iHash; 
+  int bNull = 0; 
+  int rc = SQLITE_OK;
+
+  if( pSession->rc ) return;
+
+  /* Load table details if required */
+  if( sessionInitTable(pSession, pTab) ) return;
+
+  /* Check the number of columns in this xPreUpdate call matches the 
+  ** number of columns in the table.  */
+  if( pTab->nCol!=pSession->hook.xCount(pSession->hook.pCtx) ){
+    pSession->rc = SQLITE_SCHEMA;
+    return;
+  }
+
+  /* Grow the hash table if required */
+  if( sessionGrowHash(0, pTab) ){
+    pSession->rc = SQLITE_NOMEM;
+    return;
+  }
+
+  /* Calculate the hash-key for this change. If the primary key of the row
+  ** includes a NULL value, exit early. Such changes are ignored by the
+  ** session module. */
+  rc = sessionPreupdateHash(pSession, pTab, op==SQLITE_INSERT, &iHash, &bNull);
+  if( rc!=SQLITE_OK ) goto error_out;
+
+  if( bNull==0 ){
+    /* Search the hash table for an existing record for this row. */
+    SessionChange *pC;
+    for(pC=pTab->apChange[iHash]; pC; pC=pC->pNext){
+      if( sessionPreupdateEqual(pSession, pTab, pC, op) ) break;
+    }
+
+    if( pC==0 ){
+      /* Create a new change object containing all the old values (if
+      ** this is an SQLITE_UPDATE or SQLITE_DELETE), or just the PK
+      ** values (if this is an INSERT). */
+      SessionChange *pChange; /* New change object */
+      int nByte;              /* Number of bytes to allocate */
+      int i;                  /* Used to iterate through columns */
+  
+      assert( rc==SQLITE_OK );
+      pTab->nEntry++;
+  
+      /* Figure out how large an allocation is required */
+      nByte = sizeof(SessionChange);
+      for(i=0; i<pTab->nCol; i++){
+        sqlite3_value *p = 0;
+        if( op!=SQLITE_INSERT ){
+          TESTONLY(int trc = ) pSession->hook.xOld(pSession->hook.pCtx, i, &p);
+          assert( trc==SQLITE_OK );
+        }else if( pTab->abPK[i] ){
+          TESTONLY(int trc = ) pSession->hook.xNew(pSession->hook.pCtx, i, &p);
+          assert( trc==SQLITE_OK );
+        }
+
+        /* This may fail if SQLite value p contains a utf-16 string that must
+        ** be converted to utf-8 and an OOM error occurs while doing so. */
+        rc = sessionSerializeValue(0, p, &nByte);
+        if( rc!=SQLITE_OK ) goto error_out;
+      }
+  
+      /* Allocate the change object */
+      pChange = (SessionChange *)sqlite3_malloc(nByte);
+      if( !pChange ){
+        rc = SQLITE_NOMEM;
+        goto error_out;
+      }else{
+        memset(pChange, 0, sizeof(SessionChange));
+        pChange->aRecord = (u8 *)&pChange[1];
+      }
+  
+      /* Populate the change object. None of the preupdate_old(),
+      ** preupdate_new() or SerializeValue() calls below may fail as all
+      ** required values and encodings have already been cached in memory.
+      ** It is not possible for an OOM to occur in this block. */
+      nByte = 0;
+      for(i=0; i<pTab->nCol; i++){
+        sqlite3_value *p = 0;
+        if( op!=SQLITE_INSERT ){
+          pSession->hook.xOld(pSession->hook.pCtx, i, &p);
+        }else if( pTab->abPK[i] ){
+          pSession->hook.xNew(pSession->hook.pCtx, i, &p);
+        }
+        sessionSerializeValue(&pChange->aRecord[nByte], p, &nByte);
+      }
+
+      /* Add the change to the hash-table */
+      if( pSession->bIndirect || pSession->hook.xDepth(pSession->hook.pCtx) ){
+        pChange->bIndirect = 1;
+      }
+      pChange->nRecord = nByte;
+      pChange->op = op;
+      pChange->pNext = pTab->apChange[iHash];
+      pTab->apChange[iHash] = pChange;
+
+    }else if( pC->bIndirect ){
+      /* If the existing change is considered "indirect", but this current
+      ** change is "direct", mark the change object as direct. */
+      if( pSession->hook.xDepth(pSession->hook.pCtx)==0 
+       && pSession->bIndirect==0 
+      ){
+        pC->bIndirect = 0;
+      }
+    }
+  }
+
+  /* If an error has occurred, mark the session object as failed. */
+ error_out:
+  if( rc!=SQLITE_OK ){
+    pSession->rc = rc;
+  }
+}
+
+static int sessionFindTable(
+  sqlite3_session *pSession, 
+  const char *zName,
+  SessionTable **ppTab
+){
+  int rc = SQLITE_OK;
+  int nName = sqlite3Strlen30(zName);
+  SessionTable *pRet;
+
+  /* Search for an existing table */
+  for(pRet=pSession->pTable; pRet; pRet=pRet->pNext){
+    if( 0==sqlite3_strnicmp(pRet->zName, zName, nName+1) ) break;
+  }
+
+  if( pRet==0 && pSession->bAutoAttach ){
+    /* If there is a table-filter configured, invoke it. If it returns 0,
+    ** do not automatically add the new table. */
+    if( pSession->xTableFilter==0
+     || pSession->xTableFilter(pSession->pFilterCtx, zName) 
+    ){
+      rc = sqlite3session_attach(pSession, zName);
+      if( rc==SQLITE_OK ){
+        for(pRet=pSession->pTable; pRet->pNext; pRet=pRet->pNext);
+        assert( 0==sqlite3_strnicmp(pRet->zName, zName, nName+1) );
+      }
+    }
+  }
+
+  assert( rc==SQLITE_OK || pRet==0 );
+  *ppTab = pRet;
+  return rc;
+}
+
+/*
+** The 'pre-update' hook registered by this module with SQLite databases.
+*/
+static void xPreUpdate(
+  void *pCtx,                     /* Copy of third arg to preupdate_hook() */
+  sqlite3 *db,                    /* Database handle */
+  int op,                         /* SQLITE_UPDATE, DELETE or INSERT */
+  char const *zDb,                /* Database name */
+  char const *zName,              /* Table name */
+  sqlite3_int64 iKey1,            /* Rowid of row about to be deleted/updated */
+  sqlite3_int64 iKey2             /* New rowid value (for a rowid UPDATE) */
+){
+  sqlite3_session *pSession;
+  int nDb = sqlite3Strlen30(zDb);
+
+  assert( sqlite3_mutex_held(db->mutex) );
+
+  for(pSession=(sqlite3_session *)pCtx; pSession; pSession=pSession->pNext){
+    SessionTable *pTab;
+
+    /* If this session is attached to a different database ("main", "temp" 
+    ** etc.), or if it is not currently enabled, there is nothing to do. Skip 
+    ** to the next session object attached to this database. */
+    if( pSession->bEnable==0 ) continue;
+    if( pSession->rc ) continue;
+    if( sqlite3_strnicmp(zDb, pSession->zDb, nDb+1) ) continue;
+
+    pSession->rc = sessionFindTable(pSession, zName, &pTab);
+    if( pTab ){
+      assert( pSession->rc==SQLITE_OK );
+      sessionPreupdateOneChange(op, pSession, pTab);
+      if( op==SQLITE_UPDATE ){
+        sessionPreupdateOneChange(SQLITE_INSERT, pSession, pTab);
+      }
+    }
+  }
+}
+
+/*
+** The pre-update hook implementations.
+*/
+static int sessionPreupdateOld(void *pCtx, int iVal, sqlite3_value **ppVal){
+  return sqlite3_preupdate_old((sqlite3*)pCtx, iVal, ppVal);
+}
+static int sessionPreupdateNew(void *pCtx, int iVal, sqlite3_value **ppVal){
+  return sqlite3_preupdate_new((sqlite3*)pCtx, iVal, ppVal);
+}
+static int sessionPreupdateCount(void *pCtx){
+  return sqlite3_preupdate_count((sqlite3*)pCtx);
+}
+static int sessionPreupdateDepth(void *pCtx){
+  return sqlite3_preupdate_depth((sqlite3*)pCtx);
+}
+
+/*
+** Install the pre-update hooks on the session object passed as the only
+** argument.
+*/
+static void sessionPreupdateHooks(
+  sqlite3_session *pSession
+){
+  pSession->hook.pCtx = (void*)pSession->db;
+  pSession->hook.xOld = sessionPreupdateOld;
+  pSession->hook.xNew = sessionPreupdateNew;
+  pSession->hook.xCount = sessionPreupdateCount;
+  pSession->hook.xDepth = sessionPreupdateDepth;
+}
+
+typedef struct SessionDiffCtx SessionDiffCtx;
+struct SessionDiffCtx {
+  sqlite3_stmt *pStmt;
+  int nOldOff;
+};
+
+/*
+** The diff hook implementations.
+*/
+static int sessionDiffOld(void *pCtx, int iVal, sqlite3_value **ppVal){
+  SessionDiffCtx *p = (SessionDiffCtx*)pCtx;
+  *ppVal = sqlite3_column_value(p->pStmt, iVal+p->nOldOff);
+  return SQLITE_OK;
+}
+static int sessionDiffNew(void *pCtx, int iVal, sqlite3_value **ppVal){
+  SessionDiffCtx *p = (SessionDiffCtx*)pCtx;
+  *ppVal = sqlite3_column_value(p->pStmt, iVal);
+   return SQLITE_OK;
+}
+static int sessionDiffCount(void *pCtx){
+  SessionDiffCtx *p = (SessionDiffCtx*)pCtx;
+  return p->nOldOff ? p->nOldOff : sqlite3_column_count(p->pStmt);
+}
+static int sessionDiffDepth(void *pCtx){
+  return 0;
+}
+
+/*
+** Install the diff hooks on the session object passed as the only
+** argument.
+*/
+static void sessionDiffHooks(
+  sqlite3_session *pSession,
+  SessionDiffCtx *pDiffCtx
+){
+  pSession->hook.pCtx = (void*)pDiffCtx;
+  pSession->hook.xOld = sessionDiffOld;
+  pSession->hook.xNew = sessionDiffNew;
+  pSession->hook.xCount = sessionDiffCount;
+  pSession->hook.xDepth = sessionDiffDepth;
+}
+
+static char *sessionExprComparePK(
+  int nCol,
+  const char *zDb1, const char *zDb2, 
+  const char *zTab,
+  const char **azCol, u8 *abPK
+){
+  int i;
+  const char *zSep = "";
+  char *zRet = 0;
+
+  for(i=0; i<nCol; i++){
+    if( abPK[i] ){
+      zRet = sqlite3_mprintf("%z%s\"%w\".\"%w\".\"%w\"=\"%w\".\"%w\".\"%w\"",
+          zRet, zSep, zDb1, zTab, azCol[i], zDb2, zTab, azCol[i]
+      );
+      zSep = " AND ";
+      if( zRet==0 ) break;
+    }
+  }
+
+  return zRet;
+}
+
+static char *sessionExprCompareOther(
+  int nCol,
+  const char *zDb1, const char *zDb2, 
+  const char *zTab,
+  const char **azCol, u8 *abPK
+){
+  int i;
+  const char *zSep = "";
+  char *zRet = 0;
+  int bHave = 0;
+
+  for(i=0; i<nCol; i++){
+    if( abPK[i]==0 ){
+      bHave = 1;
+      zRet = sqlite3_mprintf(
+          "%z%s\"%w\".\"%w\".\"%w\" IS NOT \"%w\".\"%w\".\"%w\"",
+          zRet, zSep, zDb1, zTab, azCol[i], zDb2, zTab, azCol[i]
+      );
+      zSep = " OR ";
+      if( zRet==0 ) break;
+    }
+  }
+
+  if( bHave==0 ){
+    assert( zRet==0 );
+    zRet = sqlite3_mprintf("0");
+  }
+
+  return zRet;
+}
+
+static char *sessionSelectFindNew(
+  int nCol,
+  const char *zDb1,      /* Pick rows in this db only */
+  const char *zDb2,      /* But not in this one */
+  const char *zTbl,      /* Table name */
+  const char *zExpr
+){
+  char *zRet = sqlite3_mprintf(
+      "SELECT * FROM \"%w\".\"%w\" WHERE NOT EXISTS ("
+      "  SELECT 1 FROM \"%w\".\"%w\" WHERE %s"
+      ")",
+      zDb1, zTbl, zDb2, zTbl, zExpr
+  );
+  return zRet;
+}
+
+static int sessionDiffFindNew(
+  int op,
+  sqlite3_session *pSession,
+  SessionTable *pTab,
+  const char *zDb1,
+  const char *zDb2,
+  char *zExpr
+){
+  int rc = SQLITE_OK;
+  char *zStmt = sessionSelectFindNew(pTab->nCol, zDb1, zDb2, pTab->zName,zExpr);
+
+  if( zStmt==0 ){
+    rc = SQLITE_NOMEM;
+  }else{
+    sqlite3_stmt *pStmt;
+    rc = sqlite3_prepare(pSession->db, zStmt, -1, &pStmt, 0);
+    if( rc==SQLITE_OK ){
+      SessionDiffCtx *pDiffCtx = (SessionDiffCtx*)pSession->hook.pCtx;
+      pDiffCtx->pStmt = pStmt;
+      pDiffCtx->nOldOff = 0;
+      while( SQLITE_ROW==sqlite3_step(pStmt) ){
+        sessionPreupdateOneChange(op, pSession, pTab);
+      }
+      rc = sqlite3_finalize(pStmt);
+    }
+    sqlite3_free(zStmt);
+  }
+
+  return rc;
+}
+
+static int sessionDiffFindModified(
+  sqlite3_session *pSession, 
+  SessionTable *pTab, 
+  const char *zFrom, 
+  const char *zExpr
+){
+  int rc = SQLITE_OK;
+
+  char *zExpr2 = sessionExprCompareOther(pTab->nCol,
+      pSession->zDb, zFrom, pTab->zName, pTab->azCol, pTab->abPK
+  );
+  if( zExpr2==0 ){
+    rc = SQLITE_NOMEM;
+  }else{
+    char *zStmt = sqlite3_mprintf(
+        "SELECT * FROM \"%w\".\"%w\", \"%w\".\"%w\" WHERE %s AND (%z)",
+        pSession->zDb, pTab->zName, zFrom, pTab->zName, zExpr, zExpr2
+    );
+    if( zStmt==0 ){
+      rc = SQLITE_NOMEM;
+    }else{
+      sqlite3_stmt *pStmt;
+      rc = sqlite3_prepare(pSession->db, zStmt, -1, &pStmt, 0);
+
+      if( rc==SQLITE_OK ){
+        SessionDiffCtx *pDiffCtx = (SessionDiffCtx*)pSession->hook.pCtx;
+        pDiffCtx->pStmt = pStmt;
+        pDiffCtx->nOldOff = pTab->nCol;
+        while( SQLITE_ROW==sqlite3_step(pStmt) ){
+          sessionPreupdateOneChange(SQLITE_UPDATE, pSession, pTab);
+        }
+        rc = sqlite3_finalize(pStmt);
+      }
+      sqlite3_free(zStmt);
+    }
+  }
+
+  return rc;
+}
+
+SQLITE_API int sqlite3session_diff(
+  sqlite3_session *pSession,
+  const char *zFrom,
+  const char *zTbl,
+  char **pzErrMsg
+){
+  const char *zDb = pSession->zDb;
+  int rc = pSession->rc;
+  SessionDiffCtx d;
+
+  memset(&d, 0, sizeof(d));
+  sessionDiffHooks(pSession, &d);
+
+  sqlite3_mutex_enter(sqlite3_db_mutex(pSession->db));
+  if( pzErrMsg ) *pzErrMsg = 0;
+  if( rc==SQLITE_OK ){
+    char *zExpr = 0;
+    sqlite3 *db = pSession->db;
+    SessionTable *pTo;            /* Table zTbl */
+
+    /* Locate and if necessary initialize the target table object */
+    rc = sessionFindTable(pSession, zTbl, &pTo);
+    if( pTo==0 ) goto diff_out;
+    if( sessionInitTable(pSession, pTo) ){
+      rc = pSession->rc;
+      goto diff_out;
+    }
+
+    /* Check the table schemas match */
+    if( rc==SQLITE_OK ){
+      int bHasPk = 0;
+      int bMismatch = 0;
+      int nCol;                   /* Columns in zFrom.zTbl */
+      u8 *abPK;
+      const char **azCol = 0;
+      rc = sessionTableInfo(db, zFrom, zTbl, &nCol, 0, &azCol, &abPK);
+      if( rc==SQLITE_OK ){
+        if( pTo->nCol!=nCol ){
+          bMismatch = 1;
+        }else{
+          int i;
+          for(i=0; i<nCol; i++){
+            if( pTo->abPK[i]!=abPK[i] ) bMismatch = 1;
+            if( sqlite3_stricmp(azCol[i], pTo->azCol[i]) ) bMismatch = 1;
+            if( abPK[i] ) bHasPk = 1;
+          }
+        }
+
+      }
+      sqlite3_free((char*)azCol);
+      if( bMismatch ){
+        *pzErrMsg = sqlite3_mprintf("table schemas do not match");
+        rc = SQLITE_SCHEMA;
+      }
+      if( bHasPk==0 ){
+        /* Ignore tables with no primary keys */
+        goto diff_out;
+      }
+    }
+
+    if( rc==SQLITE_OK ){
+      zExpr = sessionExprComparePK(pTo->nCol, 
+          zDb, zFrom, pTo->zName, pTo->azCol, pTo->abPK
+      );
+    }
+
+    /* Find new rows */
+    if( rc==SQLITE_OK ){
+      rc = sessionDiffFindNew(SQLITE_INSERT, pSession, pTo, zDb, zFrom, zExpr);
+    }
+
+    /* Find old rows */
+    if( rc==SQLITE_OK ){
+      rc = sessionDiffFindNew(SQLITE_DELETE, pSession, pTo, zFrom, zDb, zExpr);
+    }
+
+    /* Find modified rows */
+    if( rc==SQLITE_OK ){
+      rc = sessionDiffFindModified(pSession, pTo, zFrom, zExpr);
+    }
+
+    sqlite3_free(zExpr);
+  }
+
+ diff_out:
+  sessionPreupdateHooks(pSession);
+  sqlite3_mutex_leave(sqlite3_db_mutex(pSession->db));
+  return rc;
+}
+
+/*
+** Create a session object. This session object will record changes to
+** database zDb attached to connection db.
+*/
+SQLITE_API int sqlite3session_create(
+  sqlite3 *db,                    /* Database handle */
+  const char *zDb,                /* Name of db (e.g. "main") */
+  sqlite3_session **ppSession     /* OUT: New session object */
+){
+  sqlite3_session *pNew;          /* Newly allocated session object */
+  sqlite3_session *pOld;          /* Session object already attached to db */
+  int nDb = sqlite3Strlen30(zDb); /* Length of zDb in bytes */
+
+  /* Zero the output value in case an error occurs. */
+  *ppSession = 0;
+
+  /* Allocate and populate the new session object. */
+  pNew = (sqlite3_session *)sqlite3_malloc(sizeof(sqlite3_session) + nDb + 1);
+  if( !pNew ) return SQLITE_NOMEM;
+  memset(pNew, 0, sizeof(sqlite3_session));
+  pNew->db = db;
+  pNew->zDb = (char *)&pNew[1];
+  pNew->bEnable = 1;
+  memcpy(pNew->zDb, zDb, nDb+1);
+  sessionPreupdateHooks(pNew);
+
+  /* Add the new session object to the linked list of session objects 
+  ** attached to database handle $db. Do this under the cover of the db
+  ** handle mutex.  */
+  sqlite3_mutex_enter(sqlite3_db_mutex(db));
+  pOld = (sqlite3_session*)sqlite3_preupdate_hook(db, xPreUpdate, (void*)pNew);
+  pNew->pNext = pOld;
+  sqlite3_mutex_leave(sqlite3_db_mutex(db));
+
+  *ppSession = pNew;
+  return SQLITE_OK;
+}
+
+/*
+** Free the list of table objects passed as the first argument. The contents
+** of the changed-rows hash tables are also deleted.
+*/
+static void sessionDeleteTable(SessionTable *pList){
+  SessionTable *pNext;
+  SessionTable *pTab;
+
+  for(pTab=pList; pTab; pTab=pNext){
+    int i;
+    pNext = pTab->pNext;
+    for(i=0; i<pTab->nChange; i++){
+      SessionChange *p;
+      SessionChange *pNextChange;
+      for(p=pTab->apChange[i]; p; p=pNextChange){
+        pNextChange = p->pNext;
+        sqlite3_free(p);
+      }
+    }
+    sqlite3_free((char*)pTab->azCol);  /* cast works around VC++ bug */
+    sqlite3_free(pTab->apChange);
+    sqlite3_free(pTab);
+  }
+}
+
+/*
+** Delete a session object previously allocated using sqlite3session_create().
+*/
+SQLITE_API void sqlite3session_delete(sqlite3_session *pSession){
+  sqlite3 *db = pSession->db;
+  sqlite3_session *pHead;
+  sqlite3_session **pp;
+
+  /* Unlink the session from the linked list of sessions attached to the
+  ** database handle. Hold the db mutex while doing so.  */
+  sqlite3_mutex_enter(sqlite3_db_mutex(db));
+  pHead = (sqlite3_session*)sqlite3_preupdate_hook(db, 0, 0);
+  for(pp=&pHead; ALWAYS((*pp)!=0); pp=&((*pp)->pNext)){
+    if( (*pp)==pSession ){
+      *pp = (*pp)->pNext;
+      if( pHead ) sqlite3_preupdate_hook(db, xPreUpdate, (void*)pHead);
+      break;
+    }
+  }
+  sqlite3_mutex_leave(sqlite3_db_mutex(db));
+
+  /* Delete all attached table objects. And the contents of their 
+  ** associated hash-tables. */
+  sessionDeleteTable(pSession->pTable);
+
+  /* Free the session object itself. */
+  sqlite3_free(pSession);
+}
+
+/*
+** Set a table filter on a Session Object.
+*/
+SQLITE_API void sqlite3session_table_filter(
+  sqlite3_session *pSession, 
+  int(*xFilter)(void*, const char*),
+  void *pCtx                      /* First argument passed to xFilter */
+){
+  pSession->bAutoAttach = 1;
+  pSession->pFilterCtx = pCtx;
+  pSession->xTableFilter = xFilter;
+}
+
+/*
+** Attach a table to a session. All subsequent changes made to the table
+** while the session object is enabled will be recorded.
+**
+** Only tables that have a PRIMARY KEY defined may be attached. It does
+** not matter if the PRIMARY KEY is an "INTEGER PRIMARY KEY" (rowid alias)
+** or not.
+*/
+SQLITE_API int sqlite3session_attach(
+  sqlite3_session *pSession,      /* Session object */
+  const char *zName               /* Table name */
+){
+  int rc = SQLITE_OK;
+  sqlite3_mutex_enter(sqlite3_db_mutex(pSession->db));
+
+  if( !zName ){
+    pSession->bAutoAttach = 1;
+  }else{
+    SessionTable *pTab;           /* New table object (if required) */
+    int nName;                    /* Number of bytes in string zName */
+
+    /* First search for an existing entry. If one is found, this call is
+    ** a no-op. Return early. */
+    nName = sqlite3Strlen30(zName);
+    for(pTab=pSession->pTable; pTab; pTab=pTab->pNext){
+      if( 0==sqlite3_strnicmp(pTab->zName, zName, nName+1) ) break;
+    }
+
+    if( !pTab ){
+      /* Allocate new SessionTable object. */
+      pTab = (SessionTable *)sqlite3_malloc(sizeof(SessionTable) + nName + 1);
+      if( !pTab ){
+        rc = SQLITE_NOMEM;
+      }else{
+        /* Populate the new SessionTable object and link it into the list.
+        ** The new object must be linked onto the end of the list, not 
+        ** simply added to the start of it in order to ensure that tables
+        ** appear in the correct order when a changeset or patchset is
+        ** eventually generated. */
+        SessionTable **ppTab;
+        memset(pTab, 0, sizeof(SessionTable));
+        pTab->zName = (char *)&pTab[1];
+        memcpy(pTab->zName, zName, nName+1);
+        for(ppTab=&pSession->pTable; *ppTab; ppTab=&(*ppTab)->pNext);
+        *ppTab = pTab;
+      }
+    }
+  }
+
+  sqlite3_mutex_leave(sqlite3_db_mutex(pSession->db));
+  return rc;
+}
+
+/*
+** Ensure that there is room in the buffer to append nByte bytes of data.
+** If not, use sqlite3_realloc() to grow the buffer so that there is.
+**
+** If successful, return zero. Otherwise, if an OOM condition is encountered,
+** set *pRc to SQLITE_NOMEM and return non-zero.
+*/
+static int sessionBufferGrow(SessionBuffer *p, int nByte, int *pRc){
+  if( *pRc==SQLITE_OK && p->nAlloc-p->nBuf<nByte ){
+    u8 *aNew;
+    int nNew = p->nAlloc ? p->nAlloc : 128;
+    do {
+      nNew = nNew*2;
+    }while( nNew<(p->nBuf+nByte) );
+
+    aNew = (u8 *)sqlite3_realloc(p->aBuf, nNew);
+    if( 0==aNew ){
+      *pRc = SQLITE_NOMEM;
+    }else{
+      p->aBuf = aNew;
+      p->nAlloc = nNew;
+    }
+  }
+  return (*pRc!=SQLITE_OK);
+}
+
+/*
+** Append the value passed as the second argument to the buffer passed
+** as the first.
+**
+** This function is a no-op if *pRc is non-zero when it is called.
+** Otherwise, if an error occurs, *pRc is set to an SQLite error code
+** before returning.
+*/
+static void sessionAppendValue(SessionBuffer *p, sqlite3_value *pVal, int *pRc){
+  int rc = *pRc;
+  if( rc==SQLITE_OK ){
+    int nByte = 0;
+    rc = sessionSerializeValue(0, pVal, &nByte);
+    sessionBufferGrow(p, nByte, &rc);
+    if( rc==SQLITE_OK ){
+      rc = sessionSerializeValue(&p->aBuf[p->nBuf], pVal, 0);
+      p->nBuf += nByte;
+    }else{
+      *pRc = rc;
+    }
+  }
+}
+
+/*
+** This function is a no-op if *pRc is other than SQLITE_OK when it is 
+** called. Otherwise, append a single byte to the buffer. 
+**
+** If an OOM condition is encountered, set *pRc to SQLITE_NOMEM before
+** returning.
+*/
+static void sessionAppendByte(SessionBuffer *p, u8 v, int *pRc){
+  if( 0==sessionBufferGrow(p, 1, pRc) ){
+    p->aBuf[p->nBuf++] = v;
+  }
+}
+
+/*
+** This function is a no-op if *pRc is other than SQLITE_OK when it is 
+** called. Otherwise, append a single varint to the buffer. 
+**
+** If an OOM condition is encountered, set *pRc to SQLITE_NOMEM before
+** returning.
+*/
+static void sessionAppendVarint(SessionBuffer *p, int v, int *pRc){
+  if( 0==sessionBufferGrow(p, 9, pRc) ){
+    p->nBuf += sessionVarintPut(&p->aBuf[p->nBuf], v);
+  }
+}
+
+/*
+** This function is a no-op if *pRc is other than SQLITE_OK when it is 
+** called. Otherwise, append a blob of data to the buffer. 
+**
+** If an OOM condition is encountered, set *pRc to SQLITE_NOMEM before
+** returning.
+*/
+static void sessionAppendBlob(
+  SessionBuffer *p, 
+  const u8 *aBlob, 
+  int nBlob, 
+  int *pRc
+){
+  if( 0==sessionBufferGrow(p, nBlob, pRc) ){
+    memcpy(&p->aBuf[p->nBuf], aBlob, nBlob);
+    p->nBuf += nBlob;
+  }
+}
+
+/*
+** This function is a no-op if *pRc is other than SQLITE_OK when it is 
+** called. Otherwise, append a string to the buffer. All bytes in the string
+** up to (but not including) the nul-terminator are written to the buffer.
+**
+** If an OOM condition is encountered, set *pRc to SQLITE_NOMEM before
+** returning.
+*/
+static void sessionAppendStr(
+  SessionBuffer *p, 
+  const char *zStr, 
+  int *pRc
+){
+  int nStr = sqlite3Strlen30(zStr);
+  if( 0==sessionBufferGrow(p, nStr, pRc) ){
+    memcpy(&p->aBuf[p->nBuf], zStr, nStr);
+    p->nBuf += nStr;
+  }
+}
+
+/*
+** This function is a no-op if *pRc is other than SQLITE_OK when it is 
+** called. Otherwise, append the string representation of integer iVal
+** to the buffer. No nul-terminator is written.
+**
+** If an OOM condition is encountered, set *pRc to SQLITE_NOMEM before
+** returning.
+*/
+static void sessionAppendInteger(
+  SessionBuffer *p,               /* Buffer to append to */
+  int iVal,                       /* Value to write the string rep. of */
+  int *pRc                        /* IN/OUT: Error code */
+){
+  char aBuf[24];
+  sqlite3_snprintf(sizeof(aBuf)-1, aBuf, "%d", iVal);
+  sessionAppendStr(p, aBuf, pRc);
+}
+
+/*
+** This function is a no-op if *pRc is other than SQLITE_OK when it is 
+** called. Otherwise, append the string zStr enclosed in quotes (") and
+** with any embedded quote characters escaped to the buffer. No 
+** nul-terminator byte is written.
+**
+** If an OOM condition is encountered, set *pRc to SQLITE_NOMEM before
+** returning.
+*/
+static void sessionAppendIdent(
+  SessionBuffer *p,               /* Buffer to a append to */
+  const char *zStr,               /* String to quote, escape and append */
+  int *pRc                        /* IN/OUT: Error code */
+){
+  int nStr = sqlite3Strlen30(zStr)*2 + 2 + 1;
+  if( 0==sessionBufferGrow(p, nStr, pRc) ){
+    char *zOut = (char *)&p->aBuf[p->nBuf];
+    const char *zIn = zStr;
+    *zOut++ = '"';
+    while( *zIn ){
+      if( *zIn=='"' ) *zOut++ = '"';
+      *zOut++ = *(zIn++);
+    }
+    *zOut++ = '"';
+    p->nBuf = (int)((u8 *)zOut - p->aBuf);
+  }
+}
+
+/*
+** This function is a no-op if *pRc is other than SQLITE_OK when it is
+** called. Otherwse, it appends the serialized version of the value stored
+** in column iCol of the row that SQL statement pStmt currently points
+** to to the buffer.
+*/
+static void sessionAppendCol(
+  SessionBuffer *p,               /* Buffer to append to */
+  sqlite3_stmt *pStmt,            /* Handle pointing to row containing value */
+  int iCol,                       /* Column to read value from */
+  int *pRc                        /* IN/OUT: Error code */
+){
+  if( *pRc==SQLITE_OK ){
+    int eType = sqlite3_column_type(pStmt, iCol);
+    sessionAppendByte(p, (u8)eType, pRc);
+    if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
+      sqlite3_int64 i;
+      u8 aBuf[8];
+      if( eType==SQLITE_INTEGER ){
+        i = sqlite3_column_int64(pStmt, iCol);
+      }else{
+        double r = sqlite3_column_double(pStmt, iCol);
+        memcpy(&i, &r, 8);
+      }
+      sessionPutI64(aBuf, i);
+      sessionAppendBlob(p, aBuf, 8, pRc);
+    }
+    if( eType==SQLITE_BLOB || eType==SQLITE_TEXT ){
+      u8 *z;
+      int nByte;
+      if( eType==SQLITE_BLOB ){
+        z = (u8 *)sqlite3_column_blob(pStmt, iCol);
+      }else{
+        z = (u8 *)sqlite3_column_text(pStmt, iCol);
+      }
+      nByte = sqlite3_column_bytes(pStmt, iCol);
+      if( z || (eType==SQLITE_BLOB && nByte==0) ){
+        sessionAppendVarint(p, nByte, pRc);
+        sessionAppendBlob(p, z, nByte, pRc);
+      }else{
+        *pRc = SQLITE_NOMEM;
+      }
+    }
+  }
+}
+
+/*
+**
+** This function appends an update change to the buffer (see the comments 
+** under "CHANGESET FORMAT" at the top of the file). An update change 
+** consists of:
+**
+**   1 byte:  SQLITE_UPDATE (0x17)
+**   n bytes: old.* record (see RECORD FORMAT)
+**   m bytes: new.* record (see RECORD FORMAT)
+**
+** The SessionChange object passed as the third argument contains the
+** values that were stored in the row when the session began (the old.*
+** values). The statement handle passed as the second argument points
+** at the current version of the row (the new.* values).
+**
+** If all of the old.* values are equal to their corresponding new.* value
+** (i.e. nothing has changed), then no data at all is appended to the buffer.
+**
+** Otherwise, the old.* record contains all primary key values and the 
+** original values of any fields that have been modified. The new.* record 
+** contains the new values of only those fields that have been modified.
+*/ 
+static int sessionAppendUpdate(
+  SessionBuffer *pBuf,            /* Buffer to append to */
+  int bPatchset,                  /* True for "patchset", 0 for "changeset" */
+  sqlite3_stmt *pStmt,            /* Statement handle pointing at new row */
+  SessionChange *p,               /* Object containing old values */
+  u8 *abPK                        /* Boolean array - true for PK columns */
+){
+  int rc = SQLITE_OK;
+  SessionBuffer buf2 = {0,0,0}; /* Buffer to accumulate new.* record in */
+  int bNoop = 1;                /* Set to zero if any values are modified */
+  int nRewind = pBuf->nBuf;     /* Set to zero if any values are modified */
+  int i;                        /* Used to iterate through columns */
+  u8 *pCsr = p->aRecord;        /* Used to iterate through old.* values */
+
+  sessionAppendByte(pBuf, SQLITE_UPDATE, &rc);
+  sessionAppendByte(pBuf, p->bIndirect, &rc);
+  for(i=0; i<sqlite3_column_count(pStmt); i++){
+    int bChanged = 0;
+    int nAdvance;
+    int eType = *pCsr;
+    switch( eType ){
+      case SQLITE_NULL:
+        nAdvance = 1;
+        if( sqlite3_column_type(pStmt, i)!=SQLITE_NULL ){
+          bChanged = 1;
+        }
+        break;
+
+      case SQLITE_FLOAT:
+      case SQLITE_INTEGER: {
+        nAdvance = 9;
+        if( eType==sqlite3_column_type(pStmt, i) ){
+          sqlite3_int64 iVal = sessionGetI64(&pCsr[1]);
+          if( eType==SQLITE_INTEGER ){
+            if( iVal==sqlite3_column_int64(pStmt, i) ) break;
+          }else{
+            double dVal;
+            memcpy(&dVal, &iVal, 8);
+            if( dVal==sqlite3_column_double(pStmt, i) ) break;
+          }
+        }
+        bChanged = 1;
+        break;
+      }
+
+      default: {
+        int nByte;
+        int nHdr = 1 + sessionVarintGet(&pCsr[1], &nByte);
+        assert( eType==SQLITE_TEXT || eType==SQLITE_BLOB );
+        nAdvance = nHdr + nByte;
+        if( eType==sqlite3_column_type(pStmt, i) 
+         && nByte==sqlite3_column_bytes(pStmt, i) 
+         && 0==memcmp(&pCsr[nHdr], sqlite3_column_blob(pStmt, i), nByte)
+        ){
+          break;
+        }
+        bChanged = 1;
+      }
+    }
+
+    /* If at least one field has been modified, this is not a no-op. */
+    if( bChanged ) bNoop = 0;
+
+    /* Add a field to the old.* record. This is omitted if this modules is
+    ** currently generating a patchset. */
+    if( bPatchset==0 ){
+      if( bChanged || abPK[i] ){
+        sessionAppendBlob(pBuf, pCsr, nAdvance, &rc);
+      }else{
+        sessionAppendByte(pBuf, 0, &rc);
+      }
+    }
+
+    /* Add a field to the new.* record. Or the only record if currently
+    ** generating a patchset.  */
+    if( bChanged || (bPatchset && abPK[i]) ){
+      sessionAppendCol(&buf2, pStmt, i, &rc);
+    }else{
+      sessionAppendByte(&buf2, 0, &rc);
+    }
+
+    pCsr += nAdvance;
+  }
+
+  if( bNoop ){
+    pBuf->nBuf = nRewind;
+  }else{
+    sessionAppendBlob(pBuf, buf2.aBuf, buf2.nBuf, &rc);
+  }
+  sqlite3_free(buf2.aBuf);
+
+  return rc;
+}
+
+/*
+** Append a DELETE change to the buffer passed as the first argument. Use
+** the changeset format if argument bPatchset is zero, or the patchset
+** format otherwise.
+*/
+static int sessionAppendDelete(
+  SessionBuffer *pBuf,            /* Buffer to append to */
+  int bPatchset,                  /* True for "patchset", 0 for "changeset" */
+  SessionChange *p,               /* Object containing old values */
+  int nCol,                       /* Number of columns in table */
+  u8 *abPK                        /* Boolean array - true for PK columns */
+){
+  int rc = SQLITE_OK;
+
+  sessionAppendByte(pBuf, SQLITE_DELETE, &rc);
+  sessionAppendByte(pBuf, p->bIndirect, &rc);
+
+  if( bPatchset==0 ){
+    sessionAppendBlob(pBuf, p->aRecord, p->nRecord, &rc);
+  }else{
+    int i;
+    u8 *a = p->aRecord;
+    for(i=0; i<nCol; i++){
+      u8 *pStart = a;
+      int eType = *a++;
+
+      switch( eType ){
+        case 0:
+        case SQLITE_NULL:
+          assert( abPK[i]==0 );
+          break;
+
+        case SQLITE_FLOAT:
+        case SQLITE_INTEGER:
+          a += 8;
+          break;
+
+        default: {
+          int n;
+          a += sessionVarintGet(a, &n);
+          a += n;
+          break;
+        }
+      }
+      if( abPK[i] ){
+        sessionAppendBlob(pBuf, pStart, (int)(a-pStart), &rc);
+      }
+    }
+    assert( (a - p->aRecord)==p->nRecord );
+  }
+
+  return rc;
+}
+
+/*
+** Formulate and prepare a SELECT statement to retrieve a row from table
+** zTab in database zDb based on its primary key. i.e.
+**
+**   SELECT * FROM zDb.zTab WHERE pk1 = ? AND pk2 = ? AND ...
+*/
+static int sessionSelectStmt(
+  sqlite3 *db,                    /* Database handle */
+  const char *zDb,                /* Database name */
+  const char *zTab,               /* Table name */
+  int nCol,                       /* Number of columns in table */
+  const char **azCol,             /* Names of table columns */
+  u8 *abPK,                       /* PRIMARY KEY  array */
+  sqlite3_stmt **ppStmt           /* OUT: Prepared SELECT statement */
+){
+  int rc = SQLITE_OK;
+  int i;
+  const char *zSep = "";
+  SessionBuffer buf = {0, 0, 0};
+
+  sessionAppendStr(&buf, "SELECT * FROM ", &rc);
+  sessionAppendIdent(&buf, zDb, &rc);
+  sessionAppendStr(&buf, ".", &rc);
+  sessionAppendIdent(&buf, zTab, &rc);
+  sessionAppendStr(&buf, " WHERE ", &rc);
+  for(i=0; i<nCol; i++){
+    if( abPK[i] ){
+      sessionAppendStr(&buf, zSep, &rc);
+      sessionAppendIdent(&buf, azCol[i], &rc);
+      sessionAppendStr(&buf, " = ?", &rc);
+      sessionAppendInteger(&buf, i+1, &rc);
+      zSep = " AND ";
+    }
+  }
+  if( rc==SQLITE_OK ){
+    rc = sqlite3_prepare_v2(db, (char *)buf.aBuf, buf.nBuf, ppStmt, 0);
+  }
+  sqlite3_free(buf.aBuf);
+  return rc;
+}
+
+/*
+** Bind the PRIMARY KEY values from the change passed in argument pChange
+** to the SELECT statement passed as the first argument. The SELECT statement
+** is as prepared by function sessionSelectStmt().
+**
+** Return SQLITE_OK if all PK values are successfully bound, or an SQLite
+** error code (e.g. SQLITE_NOMEM) otherwise.
+*/
+static int sessionSelectBind(
+  sqlite3_stmt *pSelect,          /* SELECT from sessionSelectStmt() */
+  int nCol,                       /* Number of columns in table */
+  u8 *abPK,                       /* PRIMARY KEY array */
+  SessionChange *pChange          /* Change structure */
+){
+  int i;
+  int rc = SQLITE_OK;
+  u8 *a = pChange->aRecord;
+
+  for(i=0; i<nCol && rc==SQLITE_OK; i++){
+    int eType = *a++;
+
+    switch( eType ){
+      case 0:
+      case SQLITE_NULL:
+        assert( abPK[i]==0 );
+        break;
+
+      case SQLITE_INTEGER: {
+        if( abPK[i] ){
+          i64 iVal = sessionGetI64(a);
+          rc = sqlite3_bind_int64(pSelect, i+1, iVal);
+        }
+        a += 8;
+        break;
+      }
+
+      case SQLITE_FLOAT: {
+        if( abPK[i] ){
+          double rVal;
+          i64 iVal = sessionGetI64(a);
+          memcpy(&rVal, &iVal, 8);
+          rc = sqlite3_bind_double(pSelect, i+1, rVal);
+        }
+        a += 8;
+        break;
+      }
+
+      case SQLITE_TEXT: {
+        int n;
+        a += sessionVarintGet(a, &n);
+        if( abPK[i] ){
+          rc = sqlite3_bind_text(pSelect, i+1, (char *)a, n, SQLITE_TRANSIENT);
+        }
+        a += n;
+        break;
+      }
+
+      default: {
+        int n;
+        assert( eType==SQLITE_BLOB );
+        a += sessionVarintGet(a, &n);
+        if( abPK[i] ){
+          rc = sqlite3_bind_blob(pSelect, i+1, a, n, SQLITE_TRANSIENT);
+        }
+        a += n;
+        break;
+      }
+    }
+  }
+
+  return rc;
+}
+
+/*
+** This function is a no-op if *pRc is set to other than SQLITE_OK when it
+** is called. Otherwise, append a serialized table header (part of the binary 
+** changeset format) to buffer *pBuf. If an error occurs, set *pRc to an
+** SQLite error code before returning.
+*/
+static void sessionAppendTableHdr(
+  SessionBuffer *pBuf,            /* Append header to this buffer */
+  int bPatchset,                  /* Use the patchset format if true */
+  SessionTable *pTab,             /* Table object to append header for */
+  int *pRc                        /* IN/OUT: Error code */
+){
+  /* Write a table header */
+  sessionAppendByte(pBuf, (bPatchset ? 'P' : 'T'), pRc);
+  sessionAppendVarint(pBuf, pTab->nCol, pRc);
+  sessionAppendBlob(pBuf, pTab->abPK, pTab->nCol, pRc);
+  sessionAppendBlob(pBuf, (u8 *)pTab->zName, (int)strlen(pTab->zName)+1, pRc);
+}
+
+/*
+** Generate either a changeset (if argument bPatchset is zero) or a patchset
+** (if it is non-zero) based on the current contents of the session object
+** passed as the first argument.
+**
+** If no error occurs, SQLITE_OK is returned and the new changeset/patchset
+** stored in output variables *pnChangeset and *ppChangeset. Or, if an error
+** occurs, an SQLite error code is returned and both output variables set 
+** to 0.
+*/
+static int sessionGenerateChangeset(
+  sqlite3_session *pSession,      /* Session object */
+  int bPatchset,                  /* True for patchset, false for changeset */
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut,                     /* First argument for xOutput */
+  int *pnChangeset,               /* OUT: Size of buffer at *ppChangeset */
+  void **ppChangeset              /* OUT: Buffer containing changeset */
+){
+  sqlite3 *db = pSession->db;     /* Source database handle */
+  SessionTable *pTab;             /* Used to iterate through attached tables */
+  SessionBuffer buf = {0,0,0};    /* Buffer in which to accumlate changeset */
+  int rc;                         /* Return code */
+
+  assert( xOutput==0 || (pnChangeset==0 && ppChangeset==0 ) );
+
+  /* Zero the output variables in case an error occurs. If this session
+  ** object is already in the error state (sqlite3_session.rc != SQLITE_OK),
+  ** this call will be a no-op.  */
+  if( xOutput==0 ){
+    *pnChangeset = 0;
+    *ppChangeset = 0;
+  }
+
+  if( pSession->rc ) return pSession->rc;
+  rc = sqlite3_exec(pSession->db, "SAVEPOINT changeset", 0, 0, 0);
+  if( rc!=SQLITE_OK ) return rc;
+
+  sqlite3_mutex_enter(sqlite3_db_mutex(db));
+
+  for(pTab=pSession->pTable; rc==SQLITE_OK && pTab; pTab=pTab->pNext){
+    if( pTab->nEntry ){
+      const char *zName = pTab->zName;
+      int nCol;                   /* Number of columns in table */
+      u8 *abPK;                   /* Primary key array */
+      const char **azCol = 0;     /* Table columns */
+      int i;                      /* Used to iterate through hash buckets */
+      sqlite3_stmt *pSel = 0;     /* SELECT statement to query table pTab */
+      int nRewind = buf.nBuf;     /* Initial size of write buffer */
+      int nNoop;                  /* Size of buffer after writing tbl header */
+
+      /* Check the table schema is still Ok. */
+      rc = sessionTableInfo(db, pSession->zDb, zName, &nCol, 0, &azCol, &abPK);
+      if( !rc && (pTab->nCol!=nCol || memcmp(abPK, pTab->abPK, nCol)) ){
+        rc = SQLITE_SCHEMA;
+      }
+
+      /* Write a table header */
+      sessionAppendTableHdr(&buf, bPatchset, pTab, &rc);
+
+      /* Build and compile a statement to execute: */
+      if( rc==SQLITE_OK ){
+        rc = sessionSelectStmt(
+            db, pSession->zDb, zName, nCol, azCol, abPK, &pSel);
+      }
+
+      nNoop = buf.nBuf;
+      for(i=0; i<pTab->nChange && rc==SQLITE_OK; i++){
+        SessionChange *p;         /* Used to iterate through changes */
+
+        for(p=pTab->apChange[i]; rc==SQLITE_OK && p; p=p->pNext){
+          rc = sessionSelectBind(pSel, nCol, abPK, p);
+          if( rc!=SQLITE_OK ) continue;
+          if( sqlite3_step(pSel)==SQLITE_ROW ){
+            if( p->op==SQLITE_INSERT ){
+              int iCol;
+              sessionAppendByte(&buf, SQLITE_INSERT, &rc);
+              sessionAppendByte(&buf, p->bIndirect, &rc);
+              for(iCol=0; iCol<nCol; iCol++){
+                sessionAppendCol(&buf, pSel, iCol, &rc);
+              }
+            }else{
+              rc = sessionAppendUpdate(&buf, bPatchset, pSel, p, abPK);
+            }
+          }else if( p->op!=SQLITE_INSERT ){
+            rc = sessionAppendDelete(&buf, bPatchset, p, nCol, abPK);
+          }
+          if( rc==SQLITE_OK ){
+            rc = sqlite3_reset(pSel);
+          }
+
+          /* If the buffer is now larger than SESSIONS_STRM_CHUNK_SIZE, pass
+          ** its contents to the xOutput() callback. */
+          if( xOutput 
+           && rc==SQLITE_OK 
+           && buf.nBuf>nNoop 
+           && buf.nBuf>SESSIONS_STRM_CHUNK_SIZE 
+          ){
+            rc = xOutput(pOut, (void*)buf.aBuf, buf.nBuf);
+            nNoop = -1;
+            buf.nBuf = 0;
+          }
+
+        }
+      }
+
+      sqlite3_finalize(pSel);
+      if( buf.nBuf==nNoop ){
+        buf.nBuf = nRewind;
+      }
+      sqlite3_free((char*)azCol);  /* cast works around VC++ bug */
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    if( xOutput==0 ){
+      *pnChangeset = buf.nBuf;
+      *ppChangeset = buf.aBuf;
+      buf.aBuf = 0;
+    }else if( buf.nBuf>0 ){
+      rc = xOutput(pOut, (void*)buf.aBuf, buf.nBuf);
+    }
+  }
+
+  sqlite3_free(buf.aBuf);
+  sqlite3_exec(db, "RELEASE changeset", 0, 0, 0);
+  sqlite3_mutex_leave(sqlite3_db_mutex(db));
+  return rc;
+}
+
+/*
+** Obtain a changeset object containing all changes recorded by the 
+** session object passed as the first argument.
+**
+** It is the responsibility of the caller to eventually free the buffer 
+** using sqlite3_free().
+*/
+SQLITE_API int sqlite3session_changeset(
+  sqlite3_session *pSession,      /* Session object */
+  int *pnChangeset,               /* OUT: Size of buffer at *ppChangeset */
+  void **ppChangeset              /* OUT: Buffer containing changeset */
+){
+  return sessionGenerateChangeset(pSession, 0, 0, 0, pnChangeset, ppChangeset);
+}
+
+/*
+** Streaming version of sqlite3session_changeset().
+*/
+SQLITE_API int sqlite3session_changeset_strm(
+  sqlite3_session *pSession,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut
+){
+  return sessionGenerateChangeset(pSession, 0, xOutput, pOut, 0, 0);
+}
+
+/*
+** Streaming version of sqlite3session_patchset().
+*/
+SQLITE_API int sqlite3session_patchset_strm(
+  sqlite3_session *pSession,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut
+){
+  return sessionGenerateChangeset(pSession, 1, xOutput, pOut, 0, 0);
+}
+
+/*
+** Obtain a patchset object containing all changes recorded by the 
+** session object passed as the first argument.
+**
+** It is the responsibility of the caller to eventually free the buffer 
+** using sqlite3_free().
+*/
+SQLITE_API int sqlite3session_patchset(
+  sqlite3_session *pSession,      /* Session object */
+  int *pnPatchset,                /* OUT: Size of buffer at *ppChangeset */
+  void **ppPatchset               /* OUT: Buffer containing changeset */
+){
+  return sessionGenerateChangeset(pSession, 1, 0, 0, pnPatchset, ppPatchset);
+}
+
+/*
+** Enable or disable the session object passed as the first argument.
+*/
+SQLITE_API int sqlite3session_enable(sqlite3_session *pSession, int bEnable){
+  int ret;
+  sqlite3_mutex_enter(sqlite3_db_mutex(pSession->db));
+  if( bEnable>=0 ){
+    pSession->bEnable = bEnable;
+  }
+  ret = pSession->bEnable;
+  sqlite3_mutex_leave(sqlite3_db_mutex(pSession->db));
+  return ret;
+}
+
+/*
+** Enable or disable the session object passed as the first argument.
+*/
+SQLITE_API int sqlite3session_indirect(sqlite3_session *pSession, int bIndirect){
+  int ret;
+  sqlite3_mutex_enter(sqlite3_db_mutex(pSession->db));
+  if( bIndirect>=0 ){
+    pSession->bIndirect = bIndirect;
+  }
+  ret = pSession->bIndirect;
+  sqlite3_mutex_leave(sqlite3_db_mutex(pSession->db));
+  return ret;
+}
+
+/*
+** Return true if there have been no changes to monitored tables recorded
+** by the session object passed as the only argument.
+*/
+SQLITE_API int sqlite3session_isempty(sqlite3_session *pSession){
+  int ret = 0;
+  SessionTable *pTab;
+
+  sqlite3_mutex_enter(sqlite3_db_mutex(pSession->db));
+  for(pTab=pSession->pTable; pTab && ret==0; pTab=pTab->pNext){
+    ret = (pTab->nEntry>0);
+  }
+  sqlite3_mutex_leave(sqlite3_db_mutex(pSession->db));
+
+  return (ret==0);
+}
+
+/*
+** Do the work for either sqlite3changeset_start() or start_strm().
+*/
+static int sessionChangesetStart(
+  sqlite3_changeset_iter **pp,    /* OUT: Changeset iterator handle */
+  int (*xInput)(void *pIn, void *pData, int *pnData),
+  void *pIn,
+  int nChangeset,                 /* Size of buffer pChangeset in bytes */
+  void *pChangeset                /* Pointer to buffer containing changeset */
+){
+  sqlite3_changeset_iter *pRet;   /* Iterator to return */
+  int nByte;                      /* Number of bytes to allocate for iterator */
+
+  assert( xInput==0 || (pChangeset==0 && nChangeset==0) );
+
+  /* Zero the output variable in case an error occurs. */
+  *pp = 0;
+
+  /* Allocate and initialize the iterator structure. */
+  nByte = sizeof(sqlite3_changeset_iter);
+  pRet = (sqlite3_changeset_iter *)sqlite3_malloc(nByte);
+  if( !pRet ) return SQLITE_NOMEM;
+  memset(pRet, 0, sizeof(sqlite3_changeset_iter));
+  pRet->in.aData = (u8 *)pChangeset;
+  pRet->in.nData = nChangeset;
+  pRet->in.xInput = xInput;
+  pRet->in.pIn = pIn;
+  pRet->in.bEof = (xInput ? 0 : 1);
+
+  /* Populate the output variable and return success. */
+  *pp = pRet;
+  return SQLITE_OK;
+}
+
+/*
+** Create an iterator used to iterate through the contents of a changeset.
+*/
+SQLITE_API int sqlite3changeset_start(
+  sqlite3_changeset_iter **pp,    /* OUT: Changeset iterator handle */
+  int nChangeset,                 /* Size of buffer pChangeset in bytes */
+  void *pChangeset                /* Pointer to buffer containing changeset */
+){
+  return sessionChangesetStart(pp, 0, 0, nChangeset, pChangeset);
+}
+
+/*
+** Streaming version of sqlite3changeset_start().
+*/
+SQLITE_API int sqlite3changeset_start_strm(
+  sqlite3_changeset_iter **pp,    /* OUT: Changeset iterator handle */
+  int (*xInput)(void *pIn, void *pData, int *pnData),
+  void *pIn
+){
+  return sessionChangesetStart(pp, xInput, pIn, 0, 0);
+}
+
+/*
+** If the SessionInput object passed as the only argument is a streaming
+** object and the buffer is full, discard some data to free up space.
+*/
+static void sessionDiscardData(SessionInput *pIn){
+  if( pIn->bEof && pIn->xInput && pIn->iNext>=SESSIONS_STRM_CHUNK_SIZE ){
+    int nMove = pIn->buf.nBuf - pIn->iNext;
+    assert( nMove>=0 );
+    if( nMove>0 ){
+      memmove(pIn->buf.aBuf, &pIn->buf.aBuf[pIn->iNext], nMove);
+    }
+    pIn->buf.nBuf -= pIn->iNext;
+    pIn->iNext = 0;
+    pIn->nData = pIn->buf.nBuf;
+  }
+}
+
+/*
+** Ensure that there are at least nByte bytes available in the buffer. Or,
+** if there are not nByte bytes remaining in the input, that all available
+** data is in the buffer.
+**
+** Return an SQLite error code if an error occurs, or SQLITE_OK otherwise.
+*/
+static int sessionInputBuffer(SessionInput *pIn, int nByte){
+  int rc = SQLITE_OK;
+  if( pIn->xInput ){
+    while( !pIn->bEof && (pIn->iNext+nByte)>=pIn->nData && rc==SQLITE_OK ){
+      int nNew = SESSIONS_STRM_CHUNK_SIZE;
+
+      if( pIn->bNoDiscard==0 ) sessionDiscardData(pIn);
+      if( SQLITE_OK==sessionBufferGrow(&pIn->buf, nNew, &rc) ){
+        rc = pIn->xInput(pIn->pIn, &pIn->buf.aBuf[pIn->buf.nBuf], &nNew);
+        if( nNew==0 ){
+          pIn->bEof = 1;
+        }else{
+          pIn->buf.nBuf += nNew;
+        }
+      }
+
+      pIn->aData = pIn->buf.aBuf;
+      pIn->nData = pIn->buf.nBuf;
+    }
+  }
+  return rc;
+}
+
+/*
+** When this function is called, *ppRec points to the start of a record
+** that contains nCol values. This function advances the pointer *ppRec
+** until it points to the byte immediately following that record.
+*/
+static void sessionSkipRecord(
+  u8 **ppRec,                     /* IN/OUT: Record pointer */
+  int nCol                        /* Number of values in record */
+){
+  u8 *aRec = *ppRec;
+  int i;
+  for(i=0; i<nCol; i++){
+    int eType = *aRec++;
+    if( eType==SQLITE_TEXT || eType==SQLITE_BLOB ){
+      int nByte;
+      aRec += sessionVarintGet((u8*)aRec, &nByte);
+      aRec += nByte;
+    }else if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
+      aRec += 8;
+    }
+  }
+
+  *ppRec = aRec;
+}
+
+/*
+** This function sets the value of the sqlite3_value object passed as the
+** first argument to a copy of the string or blob held in the aData[] 
+** buffer. SQLITE_OK is returned if successful, or SQLITE_NOMEM if an OOM
+** error occurs.
+*/
+static int sessionValueSetStr(
+  sqlite3_value *pVal,            /* Set the value of this object */
+  u8 *aData,                      /* Buffer containing string or blob data */
+  int nData,                      /* Size of buffer aData[] in bytes */
+  u8 enc                          /* String encoding (0 for blobs) */
+){
+  /* In theory this code could just pass SQLITE_TRANSIENT as the final
+  ** argument to sqlite3ValueSetStr() and have the copy created 
+  ** automatically. But doing so makes it difficult to detect any OOM
+  ** error. Hence the code to create the copy externally. */
+  u8 *aCopy = sqlite3_malloc(nData+1);
+  if( aCopy==0 ) return SQLITE_NOMEM;
+  memcpy(aCopy, aData, nData);
+  sqlite3ValueSetStr(pVal, nData, (char*)aCopy, enc, sqlite3_free);
+  return SQLITE_OK;
+}
+
+/*
+** Deserialize a single record from a buffer in memory. See "RECORD FORMAT"
+** for details.
+**
+** When this function is called, *paChange points to the start of the record
+** to deserialize. Assuming no error occurs, *paChange is set to point to
+** one byte after the end of the same record before this function returns.
+** If the argument abPK is NULL, then the record contains nCol values. Or,
+** if abPK is other than NULL, then the record contains only the PK fields
+** (in other words, it is a patchset DELETE record).
+**
+** If successful, each element of the apOut[] array (allocated by the caller)
+** is set to point to an sqlite3_value object containing the value read
+** from the corresponding position in the record. If that value is not
+** included in the record (i.e. because the record is part of an UPDATE change
+** and the field was not modified), the corresponding element of apOut[] is
+** set to NULL.
+**
+** It is the responsibility of the caller to free all sqlite_value structures
+** using sqlite3_free().
+**
+** If an error occurs, an SQLite error code (e.g. SQLITE_NOMEM) is returned.
+** The apOut[] array may have been partially populated in this case.
+*/
+static int sessionReadRecord(
+  SessionInput *pIn,              /* Input data */
+  int nCol,                       /* Number of values in record */
+  u8 *abPK,                       /* Array of primary key flags, or NULL */
+  sqlite3_value **apOut           /* Write values to this array */
+){
+  int i;                          /* Used to iterate through columns */
+  int rc = SQLITE_OK;
+
+  for(i=0; i<nCol && rc==SQLITE_OK; i++){
+    int eType = 0;                /* Type of value (SQLITE_NULL, TEXT etc.) */
+    if( abPK && abPK[i]==0 ) continue;
+    rc = sessionInputBuffer(pIn, 9);
+    if( rc==SQLITE_OK ){
+      eType = pIn->aData[pIn->iNext++];
+    }
+
+    assert( apOut[i]==0 );
+    if( eType ){
+      apOut[i] = sqlite3ValueNew(0);
+      if( !apOut[i] ) rc = SQLITE_NOMEM;
+    }
+
+    if( rc==SQLITE_OK ){
+      u8 *aVal = &pIn->aData[pIn->iNext];
+      if( eType==SQLITE_TEXT || eType==SQLITE_BLOB ){
+        int nByte;
+        pIn->iNext += sessionVarintGet(aVal, &nByte);
+        rc = sessionInputBuffer(pIn, nByte);
+        if( rc==SQLITE_OK ){
+          u8 enc = (eType==SQLITE_TEXT ? SQLITE_UTF8 : 0);
+          rc = sessionValueSetStr(apOut[i],&pIn->aData[pIn->iNext],nByte,enc);
+        }
+        pIn->iNext += nByte;
+      }
+      if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
+        sqlite3_int64 v = sessionGetI64(aVal);
+        if( eType==SQLITE_INTEGER ){
+          sqlite3VdbeMemSetInt64(apOut[i], v);
+        }else{
+          double d;
+          memcpy(&d, &v, 8);
+          sqlite3VdbeMemSetDouble(apOut[i], d);
+        }
+        pIn->iNext += 8;
+      }
+    }
+  }
+
+  return rc;
+}
+
+/*
+** The input pointer currently points to the second byte of a table-header.
+** Specifically, to the following:
+**
+**   + number of columns in table (varint)
+**   + array of PK flags (1 byte per column),
+**   + table name (nul terminated).
+**
+** This function ensures that all of the above is present in the input 
+** buffer (i.e. that it can be accessed without any calls to xInput()).
+** If successful, SQLITE_OK is returned. Otherwise, an SQLite error code.
+** The input pointer is not moved.
+*/
+static int sessionChangesetBufferTblhdr(SessionInput *pIn, int *pnByte){
+  int rc = SQLITE_OK;
+  int nCol = 0;
+  int nRead = 0;
+
+  rc = sessionInputBuffer(pIn, 9);
+  if( rc==SQLITE_OK ){
+    nRead += sessionVarintGet(&pIn->aData[pIn->iNext + nRead], &nCol);
+    rc = sessionInputBuffer(pIn, nRead+nCol+100);
+    nRead += nCol;
+  }
+
+  while( rc==SQLITE_OK ){
+    while( (pIn->iNext + nRead)<pIn->nData && pIn->aData[pIn->iNext + nRead] ){
+      nRead++;
+    }
+    if( (pIn->iNext + nRead)<pIn->nData ) break;
+    rc = sessionInputBuffer(pIn, nRead + 100);
+  }
+  *pnByte = nRead+1;
+  return rc;
+}
+
+/*
+** The input pointer currently points to the first byte of the first field
+** of a record consisting of nCol columns. This function ensures the entire
+** record is buffered. It does not move the input pointer.
+**
+** If successful, SQLITE_OK is returned and *pnByte is set to the size of
+** the record in bytes. Otherwise, an SQLite error code is returned. The
+** final value of *pnByte is undefined in this case.
+*/
+static int sessionChangesetBufferRecord(
+  SessionInput *pIn,              /* Input data */
+  int nCol,                       /* Number of columns in record */
+  int *pnByte                     /* OUT: Size of record in bytes */
+){
+  int rc = SQLITE_OK;
+  int nByte = 0;
+  int i;
+  for(i=0; rc==SQLITE_OK && i<nCol; i++){
+    int eType;
+    rc = sessionInputBuffer(pIn, nByte + 10);
+    if( rc==SQLITE_OK ){
+      eType = pIn->aData[pIn->iNext + nByte++];
+      if( eType==SQLITE_TEXT || eType==SQLITE_BLOB ){
+        int n;
+        nByte += sessionVarintGet(&pIn->aData[pIn->iNext+nByte], &n);
+        nByte += n;
+        rc = sessionInputBuffer(pIn, nByte);
+      }else if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
+        nByte += 8;
+      }
+    }
+  }
+  *pnByte = nByte;
+  return rc;
+}
+
+/*
+** The input pointer currently points to the second byte of a table-header.
+** Specifically, to the following:
+**
+**   + number of columns in table (varint)
+**   + array of PK flags (1 byte per column),
+**   + table name (nul terminated).
+**
+** This function decodes the table-header and populates the p->nCol, 
+** p->zTab and p->abPK[] variables accordingly. The p->apValue[] array is 
+** also allocated or resized according to the new value of p->nCol. The
+** input pointer is left pointing to the byte following the table header.
+**
+** If successful, SQLITE_OK is returned. Otherwise, an SQLite error code
+** is returned and the final values of the various fields enumerated above
+** are undefined.
+*/
+static int sessionChangesetReadTblhdr(sqlite3_changeset_iter *p){
+  int rc;
+  int nCopy;
+  assert( p->rc==SQLITE_OK );
+
+  rc = sessionChangesetBufferTblhdr(&p->in, &nCopy);
+  if( rc==SQLITE_OK ){
+    int nByte;
+    int nVarint;
+    nVarint = sessionVarintGet(&p->in.aData[p->in.iNext], &p->nCol);
+    nCopy -= nVarint;
+    p->in.iNext += nVarint;
+    nByte = p->nCol * sizeof(sqlite3_value*) * 2 + nCopy;
+    p->tblhdr.nBuf = 0;
+    sessionBufferGrow(&p->tblhdr, nByte, &rc);
+  }
+
+  if( rc==SQLITE_OK ){
+    int iPK = sizeof(sqlite3_value*)*p->nCol*2;
+    memset(p->tblhdr.aBuf, 0, iPK);
+    memcpy(&p->tblhdr.aBuf[iPK], &p->in.aData[p->in.iNext], nCopy);
+    p->in.iNext += nCopy;
+  }
+
+  p->apValue = (sqlite3_value**)p->tblhdr.aBuf;
+  p->abPK = (u8*)&p->apValue[p->nCol*2];
+  p->zTab = (char*)&p->abPK[p->nCol];
+  return (p->rc = rc);
+}
+
+/*
+** Advance the changeset iterator to the next change.
+**
+** If both paRec and pnRec are NULL, then this function works like the public
+** API sqlite3changeset_next(). If SQLITE_ROW is returned, then the
+** sqlite3changeset_new() and old() APIs may be used to query for values.
+**
+** Otherwise, if paRec and pnRec are not NULL, then a pointer to the change
+** record is written to *paRec before returning and the number of bytes in
+** the record to *pnRec.
+**
+** Either way, this function returns SQLITE_ROW if the iterator is 
+** successfully advanced to the next change in the changeset, an SQLite 
+** error code if an error occurs, or SQLITE_DONE if there are no further 
+** changes in the changeset.
+*/
+static int sessionChangesetNext(
+  sqlite3_changeset_iter *p,      /* Changeset iterator */
+  u8 **paRec,                     /* If non-NULL, store record pointer here */
+  int *pnRec                      /* If non-NULL, store size of record here */
+){
+  int i;
+  u8 op;
+
+  assert( (paRec==0 && pnRec==0) || (paRec && pnRec) );
+
+  /* If the iterator is in the error-state, return immediately. */
+  if( p->rc!=SQLITE_OK ) return p->rc;
+
+  /* Free the current contents of p->apValue[], if any. */
+  if( p->apValue ){
+    for(i=0; i<p->nCol*2; i++){
+      sqlite3ValueFree(p->apValue[i]);
+    }
+    memset(p->apValue, 0, sizeof(sqlite3_value*)*p->nCol*2);
+  }
+
+  /* Make sure the buffer contains at least 10 bytes of input data, or all
+  ** remaining data if there are less than 10 bytes available. This is
+  ** sufficient either for the 'T' or 'P' byte and the varint that follows
+  ** it, or for the two single byte values otherwise. */
+  p->rc = sessionInputBuffer(&p->in, 2);
+  if( p->rc!=SQLITE_OK ) return p->rc;
+
+  /* If the iterator is already at the end of the changeset, return DONE. */
+  if( p->in.iNext>=p->in.nData ){
+    return SQLITE_DONE;
+  }
+
+  sessionDiscardData(&p->in);
+  p->in.iCurrent = p->in.iNext;
+
+  op = p->in.aData[p->in.iNext++];
+  if( op=='T' || op=='P' ){
+    p->bPatchset = (op=='P');
+    if( sessionChangesetReadTblhdr(p) ) return p->rc;
+    if( (p->rc = sessionInputBuffer(&p->in, 2)) ) return p->rc;
+    p->in.iCurrent = p->in.iNext;
+    op = p->in.aData[p->in.iNext++];
+  }
+
+  p->op = op;
+  p->bIndirect = p->in.aData[p->in.iNext++];
+  if( p->op!=SQLITE_UPDATE && p->op!=SQLITE_DELETE && p->op!=SQLITE_INSERT ){
+    return (p->rc = SQLITE_CORRUPT_BKPT);
+  }
+
+  if( paRec ){ 
+    int nVal;                     /* Number of values to buffer */
+    if( p->bPatchset==0 && op==SQLITE_UPDATE ){
+      nVal = p->nCol * 2;
+    }else if( p->bPatchset && op==SQLITE_DELETE ){
+      nVal = 0;
+      for(i=0; i<p->nCol; i++) if( p->abPK[i] ) nVal++;
+    }else{
+      nVal = p->nCol;
+    }
+    p->rc = sessionChangesetBufferRecord(&p->in, nVal, pnRec);
+    if( p->rc!=SQLITE_OK ) return p->rc;
+    *paRec = &p->in.aData[p->in.iNext];
+    p->in.iNext += *pnRec;
+  }else{
+
+    /* If this is an UPDATE or DELETE, read the old.* record. */
+    if( p->op!=SQLITE_INSERT && (p->bPatchset==0 || p->op==SQLITE_DELETE) ){
+      u8 *abPK = p->bPatchset ? p->abPK : 0;
+      p->rc = sessionReadRecord(&p->in, p->nCol, abPK, p->apValue);
+      if( p->rc!=SQLITE_OK ) return p->rc;
+    }
+
+    /* If this is an INSERT or UPDATE, read the new.* record. */
+    if( p->op!=SQLITE_DELETE ){
+      p->rc = sessionReadRecord(&p->in, p->nCol, 0, &p->apValue[p->nCol]);
+      if( p->rc!=SQLITE_OK ) return p->rc;
+    }
+
+    if( p->bPatchset && p->op==SQLITE_UPDATE ){
+      /* If this is an UPDATE that is part of a patchset, then all PK and
+      ** modified fields are present in the new.* record. The old.* record
+      ** is currently completely empty. This block shifts the PK fields from
+      ** new.* to old.*, to accommodate the code that reads these arrays.  */
+      for(i=0; i<p->nCol; i++){
+        assert( p->apValue[i]==0 );
+        assert( p->abPK[i]==0 || p->apValue[i+p->nCol] );
+        if( p->abPK[i] ){
+          p->apValue[i] = p->apValue[i+p->nCol];
+          p->apValue[i+p->nCol] = 0;
+        }
+      }
+    }
+  }
+
+  return SQLITE_ROW;
+}
+
+/*
+** Advance an iterator created by sqlite3changeset_start() to the next
+** change in the changeset. This function may return SQLITE_ROW, SQLITE_DONE
+** or SQLITE_CORRUPT.
+**
+** This function may not be called on iterators passed to a conflict handler
+** callback by changeset_apply().
+*/
+SQLITE_API int sqlite3changeset_next(sqlite3_changeset_iter *p){
+  return sessionChangesetNext(p, 0, 0);
+}
+
+/*
+** The following function extracts information on the current change
+** from a changeset iterator. It may only be called after changeset_next()
+** has returned SQLITE_ROW.
+*/
+SQLITE_API int sqlite3changeset_op(
+  sqlite3_changeset_iter *pIter,  /* Iterator handle */
+  const char **pzTab,             /* OUT: Pointer to table name */
+  int *pnCol,                     /* OUT: Number of columns in table */
+  int *pOp,                       /* OUT: SQLITE_INSERT, DELETE or UPDATE */
+  int *pbIndirect                 /* OUT: True if change is indirect */
+){
+  *pOp = pIter->op;
+  *pnCol = pIter->nCol;
+  *pzTab = pIter->zTab;
+  if( pbIndirect ) *pbIndirect = pIter->bIndirect;
+  return SQLITE_OK;
+}
+
+/*
+** Return information regarding the PRIMARY KEY and number of columns in
+** the database table affected by the change that pIter currently points
+** to. This function may only be called after changeset_next() returns
+** SQLITE_ROW.
+*/
+SQLITE_API int sqlite3changeset_pk(
+  sqlite3_changeset_iter *pIter,  /* Iterator object */
+  unsigned char **pabPK,          /* OUT: Array of boolean - true for PK cols */
+  int *pnCol                      /* OUT: Number of entries in output array */
+){
+  *pabPK = pIter->abPK;
+  if( pnCol ) *pnCol = pIter->nCol;
+  return SQLITE_OK;
+}
+
+/*
+** This function may only be called while the iterator is pointing to an
+** SQLITE_UPDATE or SQLITE_DELETE change (see sqlite3changeset_op()).
+** Otherwise, SQLITE_MISUSE is returned.
+**
+** It sets *ppValue to point to an sqlite3_value structure containing the
+** iVal'th value in the old.* record. Or, if that particular value is not
+** included in the record (because the change is an UPDATE and the field
+** was not modified and is not a PK column), set *ppValue to NULL.
+**
+** If value iVal is out-of-range, SQLITE_RANGE is returned and *ppValue is
+** not modified. Otherwise, SQLITE_OK.
+*/
+SQLITE_API int sqlite3changeset_old(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int iVal,                       /* Index of old.* value to retrieve */
+  sqlite3_value **ppValue         /* OUT: Old value (or NULL pointer) */
+){
+  if( pIter->op!=SQLITE_UPDATE && pIter->op!=SQLITE_DELETE ){
+    return SQLITE_MISUSE;
+  }
+  if( iVal<0 || iVal>=pIter->nCol ){
+    return SQLITE_RANGE;
+  }
+  *ppValue = pIter->apValue[iVal];
+  return SQLITE_OK;
+}
+
+/*
+** This function may only be called while the iterator is pointing to an
+** SQLITE_UPDATE or SQLITE_INSERT change (see sqlite3changeset_op()).
+** Otherwise, SQLITE_MISUSE is returned.
+**
+** It sets *ppValue to point to an sqlite3_value structure containing the
+** iVal'th value in the new.* record. Or, if that particular value is not
+** included in the record (because the change is an UPDATE and the field
+** was not modified), set *ppValue to NULL.
+**
+** If value iVal is out-of-range, SQLITE_RANGE is returned and *ppValue is
+** not modified. Otherwise, SQLITE_OK.
+*/
+SQLITE_API int sqlite3changeset_new(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int iVal,                       /* Index of new.* value to retrieve */
+  sqlite3_value **ppValue         /* OUT: New value (or NULL pointer) */
+){
+  if( pIter->op!=SQLITE_UPDATE && pIter->op!=SQLITE_INSERT ){
+    return SQLITE_MISUSE;
+  }
+  if( iVal<0 || iVal>=pIter->nCol ){
+    return SQLITE_RANGE;
+  }
+  *ppValue = pIter->apValue[pIter->nCol+iVal];
+  return SQLITE_OK;
+}
+
+/*
+** The following two macros are used internally. They are similar to the
+** sqlite3changeset_new() and sqlite3changeset_old() functions, except that
+** they omit all error checking and return a pointer to the requested value.
+*/
+#define sessionChangesetNew(pIter, iVal) (pIter)->apValue[(pIter)->nCol+(iVal)]
+#define sessionChangesetOld(pIter, iVal) (pIter)->apValue[(iVal)]
+
+/*
+** This function may only be called with a changeset iterator that has been
+** passed to an SQLITE_CHANGESET_DATA or SQLITE_CHANGESET_CONFLICT 
+** conflict-handler function. Otherwise, SQLITE_MISUSE is returned.
+**
+** If successful, *ppValue is set to point to an sqlite3_value structure
+** containing the iVal'th value of the conflicting record.
+**
+** If value iVal is out-of-range or some other error occurs, an SQLite error
+** code is returned. Otherwise, SQLITE_OK.
+*/
+SQLITE_API int sqlite3changeset_conflict(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int iVal,                       /* Index of conflict record value to fetch */
+  sqlite3_value **ppValue         /* OUT: Value from conflicting row */
+){
+  if( !pIter->pConflict ){
+    return SQLITE_MISUSE;
+  }
+  if( iVal<0 || iVal>=sqlite3_column_count(pIter->pConflict) ){
+    return SQLITE_RANGE;
+  }
+  *ppValue = sqlite3_column_value(pIter->pConflict, iVal);
+  return SQLITE_OK;
+}
+
+/*
+** This function may only be called with an iterator passed to an
+** SQLITE_CHANGESET_FOREIGN_KEY conflict handler callback. In this case
+** it sets the output variable to the total number of known foreign key
+** violations in the destination database and returns SQLITE_OK.
+**
+** In all other cases this function returns SQLITE_MISUSE.
+*/
+SQLITE_API int sqlite3changeset_fk_conflicts(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int *pnOut                      /* OUT: Number of FK violations */
+){
+  if( pIter->pConflict || pIter->apValue ){
+    return SQLITE_MISUSE;
+  }
+  *pnOut = pIter->nCol;
+  return SQLITE_OK;
+}
+
+
+/*
+** Finalize an iterator allocated with sqlite3changeset_start().
+**
+** This function may not be called on iterators passed to a conflict handler
+** callback by changeset_apply().
+*/
+SQLITE_API int sqlite3changeset_finalize(sqlite3_changeset_iter *p){
+  int rc = SQLITE_OK;
+  if( p ){
+    int i;                        /* Used to iterate through p->apValue[] */
+    rc = p->rc;
+    if( p->apValue ){
+      for(i=0; i<p->nCol*2; i++) sqlite3ValueFree(p->apValue[i]);
+    }
+    sqlite3_free(p->tblhdr.aBuf);
+    sqlite3_free(p->in.buf.aBuf);
+    sqlite3_free(p);
+  }
+  return rc;
+}
+
+static int sessionChangesetInvert(
+  SessionInput *pInput,           /* Input changeset */
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut,
+  int *pnInverted,                /* OUT: Number of bytes in output changeset */
+  void **ppInverted               /* OUT: Inverse of pChangeset */
+){
+  int rc = SQLITE_OK;             /* Return value */
+  SessionBuffer sOut;             /* Output buffer */
+  int nCol = 0;                   /* Number of cols in current table */
+  u8 *abPK = 0;                   /* PK array for current table */
+  sqlite3_value **apVal = 0;      /* Space for values for UPDATE inversion */
+  SessionBuffer sPK = {0, 0, 0};  /* PK array for current table */
+
+  /* Initialize the output buffer */
+  memset(&sOut, 0, sizeof(SessionBuffer));
+
+  /* Zero the output variables in case an error occurs. */
+  if( ppInverted ){
+    *ppInverted = 0;
+    *pnInverted = 0;
+  }
+
+  while( 1 ){
+    u8 eType;
+
+    /* Test for EOF. */
+    if( (rc = sessionInputBuffer(pInput, 2)) ) goto finished_invert;
+    if( pInput->iNext>=pInput->nData ) break;
+    eType = pInput->aData[pInput->iNext];
+
+    switch( eType ){
+      case 'T': {
+        /* A 'table' record consists of:
+        **
+        **   * A constant 'T' character,
+        **   * Number of columns in said table (a varint),
+        **   * An array of nCol bytes (sPK),
+        **   * A nul-terminated table name.
+        */
+        int nByte;
+        int nVar;
+        pInput->iNext++;
+        if( (rc = sessionChangesetBufferTblhdr(pInput, &nByte)) ){
+          goto finished_invert;
+        }
+        nVar = sessionVarintGet(&pInput->aData[pInput->iNext], &nCol);
+        sPK.nBuf = 0;
+        sessionAppendBlob(&sPK, &pInput->aData[pInput->iNext+nVar], nCol, &rc);
+        sessionAppendByte(&sOut, eType, &rc);
+        sessionAppendBlob(&sOut, &pInput->aData[pInput->iNext], nByte, &rc);
+        if( rc ) goto finished_invert;
+
+        pInput->iNext += nByte;
+        sqlite3_free(apVal);
+        apVal = 0;
+        abPK = sPK.aBuf;
+        break;
+      }
+
+      case SQLITE_INSERT:
+      case SQLITE_DELETE: {
+        int nByte;
+        int bIndirect = pInput->aData[pInput->iNext+1];
+        int eType2 = (eType==SQLITE_DELETE ? SQLITE_INSERT : SQLITE_DELETE);
+        pInput->iNext += 2;
+        assert( rc==SQLITE_OK );
+        rc = sessionChangesetBufferRecord(pInput, nCol, &nByte);
+        sessionAppendByte(&sOut, eType2, &rc);
+        sessionAppendByte(&sOut, bIndirect, &rc);
+        sessionAppendBlob(&sOut, &pInput->aData[pInput->iNext], nByte, &rc);
+        pInput->iNext += nByte;
+        if( rc ) goto finished_invert;
+        break;
+      }
+
+      case SQLITE_UPDATE: {
+        int iCol;
+
+        if( 0==apVal ){
+          apVal = (sqlite3_value **)sqlite3_malloc(sizeof(apVal[0])*nCol*2);
+          if( 0==apVal ){
+            rc = SQLITE_NOMEM;
+            goto finished_invert;
+          }
+          memset(apVal, 0, sizeof(apVal[0])*nCol*2);
+        }
+
+        /* Write the header for the new UPDATE change. Same as the original. */
+        sessionAppendByte(&sOut, eType, &rc);
+        sessionAppendByte(&sOut, pInput->aData[pInput->iNext+1], &rc);
+
+        /* Read the old.* and new.* records for the update change. */
+        pInput->iNext += 2;
+        rc = sessionReadRecord(pInput, nCol, 0, &apVal[0]);
+        if( rc==SQLITE_OK ){
+          rc = sessionReadRecord(pInput, nCol, 0, &apVal[nCol]);
+        }
+
+        /* Write the new old.* record. Consists of the PK columns from the
+        ** original old.* record, and the other values from the original
+        ** new.* record. */
+        for(iCol=0; iCol<nCol; iCol++){
+          sqlite3_value *pVal = apVal[iCol + (abPK[iCol] ? 0 : nCol)];
+          sessionAppendValue(&sOut, pVal, &rc);
+        }
+
+        /* Write the new new.* record. Consists of a copy of all values
+        ** from the original old.* record, except for the PK columns, which
+        ** are set to "undefined". */
+        for(iCol=0; iCol<nCol; iCol++){
+          sqlite3_value *pVal = (abPK[iCol] ? 0 : apVal[iCol]);
+          sessionAppendValue(&sOut, pVal, &rc);
+        }
+
+        for(iCol=0; iCol<nCol*2; iCol++){
+          sqlite3ValueFree(apVal[iCol]);
+        }
+        memset(apVal, 0, sizeof(apVal[0])*nCol*2);
+        if( rc!=SQLITE_OK ){
+          goto finished_invert;
+        }
+
+        break;
+      }
+
+      default:
+        rc = SQLITE_CORRUPT_BKPT;
+        goto finished_invert;
+    }
+
+    assert( rc==SQLITE_OK );
+    if( xOutput && sOut.nBuf>=SESSIONS_STRM_CHUNK_SIZE ){
+      rc = xOutput(pOut, sOut.aBuf, sOut.nBuf);
+      sOut.nBuf = 0;
+      if( rc!=SQLITE_OK ) goto finished_invert;
+    }
+  }
+
+  assert( rc==SQLITE_OK );
+  if( pnInverted ){
+    *pnInverted = sOut.nBuf;
+    *ppInverted = sOut.aBuf;
+    sOut.aBuf = 0;
+  }else if( sOut.nBuf>0 ){
+    rc = xOutput(pOut, sOut.aBuf, sOut.nBuf);
+  }
+
+ finished_invert:
+  sqlite3_free(sOut.aBuf);
+  sqlite3_free(apVal);
+  sqlite3_free(sPK.aBuf);
+  return rc;
+}
+
+
+/*
+** Invert a changeset object.
+*/
+SQLITE_API int sqlite3changeset_invert(
+  int nChangeset,                 /* Number of bytes in input */
+  const void *pChangeset,         /* Input changeset */
+  int *pnInverted,                /* OUT: Number of bytes in output changeset */
+  void **ppInverted               /* OUT: Inverse of pChangeset */
+){
+  SessionInput sInput;
+
+  /* Set up the input stream */
+  memset(&sInput, 0, sizeof(SessionInput));
+  sInput.nData = nChangeset;
+  sInput.aData = (u8*)pChangeset;
+
+  return sessionChangesetInvert(&sInput, 0, 0, pnInverted, ppInverted);
+}
+
+/*
+** Streaming version of sqlite3changeset_invert().
+*/
+SQLITE_API int sqlite3changeset_invert_strm(
+  int (*xInput)(void *pIn, void *pData, int *pnData),
+  void *pIn,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut
+){
+  SessionInput sInput;
+  int rc;
+
+  /* Set up the input stream */
+  memset(&sInput, 0, sizeof(SessionInput));
+  sInput.xInput = xInput;
+  sInput.pIn = pIn;
+
+  rc = sessionChangesetInvert(&sInput, xOutput, pOut, 0, 0);
+  sqlite3_free(sInput.buf.aBuf);
+  return rc;
+}
+
+typedef struct SessionApplyCtx SessionApplyCtx;
+struct SessionApplyCtx {
+  sqlite3 *db;
+  sqlite3_stmt *pDelete;          /* DELETE statement */
+  sqlite3_stmt *pUpdate;          /* UPDATE statement */
+  sqlite3_stmt *pInsert;          /* INSERT statement */
+  sqlite3_stmt *pSelect;          /* SELECT statement */
+  int nCol;                       /* Size of azCol[] and abPK[] arrays */
+  const char **azCol;             /* Array of column names */
+  u8 *abPK;                       /* Boolean array - true if column is in PK */
+
+  int bDeferConstraints;          /* True to defer constraints */
+  SessionBuffer constraints;      /* Deferred constraints are stored here */
+};
+
+/*
+** Formulate a statement to DELETE a row from database db. Assuming a table
+** structure like this:
+**
+**     CREATE TABLE x(a, b, c, d, PRIMARY KEY(a, c));
+**
+** The DELETE statement looks like this:
+**
+**     DELETE FROM x WHERE a = :1 AND c = :3 AND (:5 OR b IS :2 AND d IS :4)
+**
+** Variable :5 (nCol+1) is a boolean. It should be set to 0 if we require
+** matching b and d values, or 1 otherwise. The second case comes up if the
+** conflict handler is invoked with NOTFOUND and returns CHANGESET_REPLACE.
+**
+** If successful, SQLITE_OK is returned and SessionApplyCtx.pDelete is left
+** pointing to the prepared version of the SQL statement.
+*/
+static int sessionDeleteRow(
+  sqlite3 *db,                    /* Database handle */
+  const char *zTab,               /* Table name */
+  SessionApplyCtx *p              /* Session changeset-apply context */
+){
+  int i;
+  const char *zSep = "";
+  int rc = SQLITE_OK;
+  SessionBuffer buf = {0, 0, 0};
+  int nPk = 0;
+
+  sessionAppendStr(&buf, "DELETE FROM ", &rc);
+  sessionAppendIdent(&buf, zTab, &rc);
+  sessionAppendStr(&buf, " WHERE ", &rc);
+
+  for(i=0; i<p->nCol; i++){
+    if( p->abPK[i] ){
+      nPk++;
+      sessionAppendStr(&buf, zSep, &rc);
+      sessionAppendIdent(&buf, p->azCol[i], &rc);
+      sessionAppendStr(&buf, " = ?", &rc);
+      sessionAppendInteger(&buf, i+1, &rc);
+      zSep = " AND ";
+    }
+  }
+
+  if( nPk<p->nCol ){
+    sessionAppendStr(&buf, " AND (?", &rc);
+    sessionAppendInteger(&buf, p->nCol+1, &rc);
+    sessionAppendStr(&buf, " OR ", &rc);
+
+    zSep = "";
+    for(i=0; i<p->nCol; i++){
+      if( !p->abPK[i] ){
+        sessionAppendStr(&buf, zSep, &rc);
+        sessionAppendIdent(&buf, p->azCol[i], &rc);
+        sessionAppendStr(&buf, " IS ?", &rc);
+        sessionAppendInteger(&buf, i+1, &rc);
+        zSep = "AND ";
+      }
+    }
+    sessionAppendStr(&buf, ")", &rc);
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = sqlite3_prepare_v2(db, (char *)buf.aBuf, buf.nBuf, &p->pDelete, 0);
+  }
+  sqlite3_free(buf.aBuf);
+
+  return rc;
+}
+
+/*
+** Formulate and prepare a statement to UPDATE a row from database db. 
+** Assuming a table structure like this:
+**
+**     CREATE TABLE x(a, b, c, d, PRIMARY KEY(a, c));
+**
+** The UPDATE statement looks like this:
+**
+**     UPDATE x SET
+**     a = CASE WHEN ?2  THEN ?3  ELSE a END,
+**     b = CASE WHEN ?5  THEN ?6  ELSE b END,
+**     c = CASE WHEN ?8  THEN ?9  ELSE c END,
+**     d = CASE WHEN ?11 THEN ?12 ELSE d END
+**     WHERE a = ?1 AND c = ?7 AND (?13 OR 
+**       (?5==0 OR b IS ?4) AND (?11==0 OR d IS ?10) AND
+**     )
+**
+** For each column in the table, there are three variables to bind:
+**
+**     ?(i*3+1)    The old.* value of the column, if any.
+**     ?(i*3+2)    A boolean flag indicating that the value is being modified.
+**     ?(i*3+3)    The new.* value of the column, if any.
+**
+** Also, a boolean flag that, if set to true, causes the statement to update
+** a row even if the non-PK values do not match. This is required if the
+** conflict-handler is invoked with CHANGESET_DATA and returns
+** CHANGESET_REPLACE. This is variable "?(nCol*3+1)".
+**
+** If successful, SQLITE_OK is returned and SessionApplyCtx.pUpdate is left
+** pointing to the prepared version of the SQL statement.
+*/
+static int sessionUpdateRow(
+  sqlite3 *db,                    /* Database handle */
+  const char *zTab,               /* Table name */
+  SessionApplyCtx *p              /* Session changeset-apply context */
+){
+  int rc = SQLITE_OK;
+  int i;
+  const char *zSep = "";
+  SessionBuffer buf = {0, 0, 0};
+
+  /* Append "UPDATE tbl SET " */
+  sessionAppendStr(&buf, "UPDATE ", &rc);
+  sessionAppendIdent(&buf, zTab, &rc);
+  sessionAppendStr(&buf, " SET ", &rc);
+
+  /* Append the assignments */
+  for(i=0; i<p->nCol; i++){
+    sessionAppendStr(&buf, zSep, &rc);
+    sessionAppendIdent(&buf, p->azCol[i], &rc);
+    sessionAppendStr(&buf, " = CASE WHEN ?", &rc);
+    sessionAppendInteger(&buf, i*3+2, &rc);
+    sessionAppendStr(&buf, " THEN ?", &rc);
+    sessionAppendInteger(&buf, i*3+3, &rc);
+    sessionAppendStr(&buf, " ELSE ", &rc);
+    sessionAppendIdent(&buf, p->azCol[i], &rc);
+    sessionAppendStr(&buf, " END", &rc);
+    zSep = ", ";
+  }
+
+  /* Append the PK part of the WHERE clause */
+  sessionAppendStr(&buf, " WHERE ", &rc);
+  for(i=0; i<p->nCol; i++){
+    if( p->abPK[i] ){
+      sessionAppendIdent(&buf, p->azCol[i], &rc);
+      sessionAppendStr(&buf, " = ?", &rc);
+      sessionAppendInteger(&buf, i*3+1, &rc);
+      sessionAppendStr(&buf, " AND ", &rc);
+    }
+  }
+
+  /* Append the non-PK part of the WHERE clause */
+  sessionAppendStr(&buf, " (?", &rc);
+  sessionAppendInteger(&buf, p->nCol*3+1, &rc);
+  sessionAppendStr(&buf, " OR 1", &rc);
+  for(i=0; i<p->nCol; i++){
+    if( !p->abPK[i] ){
+      sessionAppendStr(&buf, " AND (?", &rc);
+      sessionAppendInteger(&buf, i*3+2, &rc);
+      sessionAppendStr(&buf, "=0 OR ", &rc);
+      sessionAppendIdent(&buf, p->azCol[i], &rc);
+      sessionAppendStr(&buf, " IS ?", &rc);
+      sessionAppendInteger(&buf, i*3+1, &rc);
+      sessionAppendStr(&buf, ")", &rc);
+    }
+  }
+  sessionAppendStr(&buf, ")", &rc);
+
+  if( rc==SQLITE_OK ){
+    rc = sqlite3_prepare_v2(db, (char *)buf.aBuf, buf.nBuf, &p->pUpdate, 0);
+  }
+  sqlite3_free(buf.aBuf);
+
+  return rc;
+}
+
+/*
+** Formulate and prepare an SQL statement to query table zTab by primary
+** key. Assuming the following table structure:
+**
+**     CREATE TABLE x(a, b, c, d, PRIMARY KEY(a, c));
+**
+** The SELECT statement looks like this:
+**
+**     SELECT * FROM x WHERE a = ?1 AND c = ?3
+**
+** If successful, SQLITE_OK is returned and SessionApplyCtx.pSelect is left
+** pointing to the prepared version of the SQL statement.
+*/
+static int sessionSelectRow(
+  sqlite3 *db,                    /* Database handle */
+  const char *zTab,               /* Table name */
+  SessionApplyCtx *p              /* Session changeset-apply context */
+){
+  return sessionSelectStmt(
+      db, "main", zTab, p->nCol, p->azCol, p->abPK, &p->pSelect);
+}
+
+/*
+** Formulate and prepare an INSERT statement to add a record to table zTab.
+** For example:
+**
+**     INSERT INTO main."zTab" VALUES(?1, ?2, ?3 ...);
+**
+** If successful, SQLITE_OK is returned and SessionApplyCtx.pInsert is left
+** pointing to the prepared version of the SQL statement.
+*/
+static int sessionInsertRow(
+  sqlite3 *db,                    /* Database handle */
+  const char *zTab,               /* Table name */
+  SessionApplyCtx *p              /* Session changeset-apply context */
+){
+  int rc = SQLITE_OK;
+  int i;
+  SessionBuffer buf = {0, 0, 0};
+
+  sessionAppendStr(&buf, "INSERT INTO main.", &rc);
+  sessionAppendIdent(&buf, zTab, &rc);
+  sessionAppendStr(&buf, " VALUES(?", &rc);
+  for(i=1; i<p->nCol; i++){
+    sessionAppendStr(&buf, ", ?", &rc);
+  }
+  sessionAppendStr(&buf, ")", &rc);
+
+  if( rc==SQLITE_OK ){
+    rc = sqlite3_prepare_v2(db, (char *)buf.aBuf, buf.nBuf, &p->pInsert, 0);
+  }
+  sqlite3_free(buf.aBuf);
+  return rc;
+}
+
+/*
+** A wrapper around sqlite3_bind_value() that detects an extra problem. 
+** See comments in the body of this function for details.
+*/
+static int sessionBindValue(
+  sqlite3_stmt *pStmt,            /* Statement to bind value to */
+  int i,                          /* Parameter number to bind to */
+  sqlite3_value *pVal             /* Value to bind */
+){
+  int eType = sqlite3_value_type(pVal);
+  /* COVERAGE: The (pVal->z==0) branch is never true using current versions
+  ** of SQLite. If a malloc fails in an sqlite3_value_xxx() function, either
+  ** the (pVal->z) variable remains as it was or the type of the value is
+  ** set to SQLITE_NULL.  */
+  if( (eType==SQLITE_TEXT || eType==SQLITE_BLOB) && pVal->z==0 ){
+    /* This condition occurs when an earlier OOM in a call to
+    ** sqlite3_value_text() or sqlite3_value_blob() (perhaps from within
+    ** a conflict-handler) has zeroed the pVal->z pointer. Return NOMEM. */
+    return SQLITE_NOMEM;
+  }
+  return sqlite3_bind_value(pStmt, i, pVal);
+}
+
+/*
+** Iterator pIter must point to an SQLITE_INSERT entry. This function 
+** transfers new.* values from the current iterator entry to statement
+** pStmt. The table being inserted into has nCol columns.
+**
+** New.* value $i from the iterator is bound to variable ($i+1) of 
+** statement pStmt. If parameter abPK is NULL, all values from 0 to (nCol-1)
+** are transfered to the statement. Otherwise, if abPK is not NULL, it points
+** to an array nCol elements in size. In this case only those values for 
+** which abPK[$i] is true are read from the iterator and bound to the 
+** statement.
+**
+** An SQLite error code is returned if an error occurs. Otherwise, SQLITE_OK.
+*/
+static int sessionBindRow(
+  sqlite3_changeset_iter *pIter,  /* Iterator to read values from */
+  int(*xValue)(sqlite3_changeset_iter *, int, sqlite3_value **),
+  int nCol,                       /* Number of columns */
+  u8 *abPK,                       /* If not NULL, bind only if true */
+  sqlite3_stmt *pStmt             /* Bind values to this statement */
+){
+  int i;
+  int rc = SQLITE_OK;
+
+  /* Neither sqlite3changeset_old or sqlite3changeset_new can fail if the
+  ** argument iterator points to a suitable entry. Make sure that xValue 
+  ** is one of these to guarantee that it is safe to ignore the return 
+  ** in the code below. */
+  assert( xValue==sqlite3changeset_old || xValue==sqlite3changeset_new );
+
+  for(i=0; rc==SQLITE_OK && i<nCol; i++){
+    if( !abPK || abPK[i] ){
+      sqlite3_value *pVal;
+      (void)xValue(pIter, i, &pVal);
+      rc = sessionBindValue(pStmt, i+1, pVal);
+    }
+  }
+  return rc;
+}
+
+/*
+** SQL statement pSelect is as generated by the sessionSelectRow() function.
+** This function binds the primary key values from the change that changeset
+** iterator pIter points to to the SELECT and attempts to seek to the table
+** entry. If a row is found, the SELECT statement left pointing at the row 
+** and SQLITE_ROW is returned. Otherwise, if no row is found and no error
+** has occured, the statement is reset and SQLITE_OK is returned. If an
+** error occurs, the statement is reset and an SQLite error code is returned.
+**
+** If this function returns SQLITE_ROW, the caller must eventually reset() 
+** statement pSelect. If any other value is returned, the statement does
+** not require a reset().
+**
+** If the iterator currently points to an INSERT record, bind values from the
+** new.* record to the SELECT statement. Or, if it points to a DELETE or
+** UPDATE, bind values from the old.* record. 
+*/
+static int sessionSeekToRow(
+  sqlite3 *db,                    /* Database handle */
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  u8 *abPK,                       /* Primary key flags array */
+  sqlite3_stmt *pSelect           /* SELECT statement from sessionSelectRow() */
+){
+  int rc;                         /* Return code */
+  int nCol;                       /* Number of columns in table */
+  int op;                         /* Changset operation (SQLITE_UPDATE etc.) */
+  const char *zDummy;             /* Unused */
+
+  sqlite3changeset_op(pIter, &zDummy, &nCol, &op, 0);
+  rc = sessionBindRow(pIter, 
+      op==SQLITE_INSERT ? sqlite3changeset_new : sqlite3changeset_old,
+      nCol, abPK, pSelect
+  );
+
+  if( rc==SQLITE_OK ){
+    rc = sqlite3_step(pSelect);
+    if( rc!=SQLITE_ROW ) rc = sqlite3_reset(pSelect);
+  }
+
+  return rc;
+}
+
+/*
+** Invoke the conflict handler for the change that the changeset iterator
+** currently points to.
+**
+** Argument eType must be either CHANGESET_DATA or CHANGESET_CONFLICT.
+** If argument pbReplace is NULL, then the type of conflict handler invoked
+** depends solely on eType, as follows:
+**
+**    eType value                 Value passed to xConflict
+**    -------------------------------------------------
+**    CHANGESET_DATA              CHANGESET_NOTFOUND
+**    CHANGESET_CONFLICT          CHANGESET_CONSTRAINT
+**
+** Or, if pbReplace is not NULL, then an attempt is made to find an existing
+** record with the same primary key as the record about to be deleted, updated
+** or inserted. If such a record can be found, it is available to the conflict
+** handler as the "conflicting" record. In this case the type of conflict
+** handler invoked is as follows:
+**
+**    eType value         PK Record found?   Value passed to xConflict
+**    ----------------------------------------------------------------
+**    CHANGESET_DATA      Yes                CHANGESET_DATA
+**    CHANGESET_DATA      No                 CHANGESET_NOTFOUND
+**    CHANGESET_CONFLICT  Yes                CHANGESET_CONFLICT
+**    CHANGESET_CONFLICT  No                 CHANGESET_CONSTRAINT
+**
+** If pbReplace is not NULL, and a record with a matching PK is found, and
+** the conflict handler function returns SQLITE_CHANGESET_REPLACE, *pbReplace
+** is set to non-zero before returning SQLITE_OK.
+**
+** If the conflict handler returns SQLITE_CHANGESET_ABORT, SQLITE_ABORT is
+** returned. Or, if the conflict handler returns an invalid value, 
+** SQLITE_MISUSE. If the conflict handler returns SQLITE_CHANGESET_OMIT,
+** this function returns SQLITE_OK.
+*/
+static int sessionConflictHandler(
+  int eType,                      /* Either CHANGESET_DATA or CONFLICT */
+  SessionApplyCtx *p,             /* changeset_apply() context */
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int(*xConflict)(void *, int, sqlite3_changeset_iter*),
+  void *pCtx,                     /* First argument for conflict handler */
+  int *pbReplace                  /* OUT: Set to true if PK row is found */
+){
+  int res = 0;                    /* Value returned by conflict handler */
+  int rc;
+  int nCol;
+  int op;
+  const char *zDummy;
+
+  sqlite3changeset_op(pIter, &zDummy, &nCol, &op, 0);
+
+  assert( eType==SQLITE_CHANGESET_CONFLICT || eType==SQLITE_CHANGESET_DATA );
+  assert( SQLITE_CHANGESET_CONFLICT+1==SQLITE_CHANGESET_CONSTRAINT );
+  assert( SQLITE_CHANGESET_DATA+1==SQLITE_CHANGESET_NOTFOUND );
+
+  /* Bind the new.* PRIMARY KEY values to the SELECT statement. */
+  if( pbReplace ){
+    rc = sessionSeekToRow(p->db, pIter, p->abPK, p->pSelect);
+  }else{
+    rc = SQLITE_OK;
+  }
+
+  if( rc==SQLITE_ROW ){
+    /* There exists another row with the new.* primary key. */
+    pIter->pConflict = p->pSelect;
+    res = xConflict(pCtx, eType, pIter);
+    pIter->pConflict = 0;
+    rc = sqlite3_reset(p->pSelect);
+  }else if( rc==SQLITE_OK ){
+    if( p->bDeferConstraints && eType==SQLITE_CHANGESET_CONFLICT ){
+      /* Instead of invoking the conflict handler, append the change blob
+      ** to the SessionApplyCtx.constraints buffer. */
+      u8 *aBlob = &pIter->in.aData[pIter->in.iCurrent];
+      int nBlob = pIter->in.iNext - pIter->in.iCurrent;
+      sessionAppendBlob(&p->constraints, aBlob, nBlob, &rc);
+      res = SQLITE_CHANGESET_OMIT;
+    }else{
+      /* No other row with the new.* primary key. */
+      res = xConflict(pCtx, eType+1, pIter);
+      if( res==SQLITE_CHANGESET_REPLACE ) rc = SQLITE_MISUSE;
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    switch( res ){
+      case SQLITE_CHANGESET_REPLACE:
+        assert( pbReplace );
+        *pbReplace = 1;
+        break;
+
+      case SQLITE_CHANGESET_OMIT:
+        break;
+
+      case SQLITE_CHANGESET_ABORT:
+        rc = SQLITE_ABORT;
+        break;
+
+      default:
+        rc = SQLITE_MISUSE;
+        break;
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Attempt to apply the change that the iterator passed as the first argument
+** currently points to to the database. If a conflict is encountered, invoke
+** the conflict handler callback.
+**
+** If argument pbRetry is NULL, then ignore any CHANGESET_DATA conflict. If
+** one is encountered, update or delete the row with the matching primary key
+** instead. Or, if pbRetry is not NULL and a CHANGESET_DATA conflict occurs,
+** invoke the conflict handler. If it returns CHANGESET_REPLACE, set *pbRetry
+** to true before returning. In this case the caller will invoke this function
+** again, this time with pbRetry set to NULL.
+**
+** If argument pbReplace is NULL and a CHANGESET_CONFLICT conflict is 
+** encountered invoke the conflict handler with CHANGESET_CONSTRAINT instead.
+** Or, if pbReplace is not NULL, invoke it with CHANGESET_CONFLICT. If such
+** an invocation returns SQLITE_CHANGESET_REPLACE, set *pbReplace to true
+** before retrying. In this case the caller attempts to remove the conflicting
+** row before invoking this function again, this time with pbReplace set 
+** to NULL.
+**
+** If any conflict handler returns SQLITE_CHANGESET_ABORT, this function
+** returns SQLITE_ABORT. Otherwise, if no error occurs, SQLITE_OK is 
+** returned.
+*/
+static int sessionApplyOneOp(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  SessionApplyCtx *p,             /* changeset_apply() context */
+  int(*xConflict)(void *, int, sqlite3_changeset_iter *),
+  void *pCtx,                     /* First argument for the conflict handler */
+  int *pbReplace,                 /* OUT: True to remove PK row and retry */
+  int *pbRetry                    /* OUT: True to retry. */
+){
+  const char *zDummy;
+  int op;
+  int nCol;
+  int rc = SQLITE_OK;
+
+  assert( p->pDelete && p->pUpdate && p->pInsert && p->pSelect );
+  assert( p->azCol && p->abPK );
+  assert( !pbReplace || *pbReplace==0 );
+
+  sqlite3changeset_op(pIter, &zDummy, &nCol, &op, 0);
+
+  if( op==SQLITE_DELETE ){
+
+    /* Bind values to the DELETE statement. If conflict handling is required,
+    ** bind values for all columns and set bound variable (nCol+1) to true.
+    ** Or, if conflict handling is not required, bind just the PK column
+    ** values and, if it exists, set (nCol+1) to false. Conflict handling
+    ** is not required if:
+    **
+    **   * this is a patchset, or
+    **   * (pbRetry==0), or
+    **   * all columns of the table are PK columns (in this case there is
+    **     no (nCol+1) variable to bind to).
+    */
+    u8 *abPK = (pIter->bPatchset ? p->abPK : 0);
+    rc = sessionBindRow(pIter, sqlite3changeset_old, nCol, abPK, p->pDelete);
+    if( rc==SQLITE_OK && sqlite3_bind_parameter_count(p->pDelete)>nCol ){
+      rc = sqlite3_bind_int(p->pDelete, nCol+1, (pbRetry==0 || abPK));
+    }
+    if( rc!=SQLITE_OK ) return rc;
+
+    sqlite3_step(p->pDelete);
+    rc = sqlite3_reset(p->pDelete);
+    if( rc==SQLITE_OK && sqlite3_changes(p->db)==0 ){
+      rc = sessionConflictHandler(
+          SQLITE_CHANGESET_DATA, p, pIter, xConflict, pCtx, pbRetry
+      );
+    }else if( (rc&0xff)==SQLITE_CONSTRAINT ){
+      rc = sessionConflictHandler(
+          SQLITE_CHANGESET_CONFLICT, p, pIter, xConflict, pCtx, 0
+      );
+    }
+
+  }else if( op==SQLITE_UPDATE ){
+    int i;
+
+    /* Bind values to the UPDATE statement. */
+    for(i=0; rc==SQLITE_OK && i<nCol; i++){
+      sqlite3_value *pOld = sessionChangesetOld(pIter, i);
+      sqlite3_value *pNew = sessionChangesetNew(pIter, i);
+
+      sqlite3_bind_int(p->pUpdate, i*3+2, !!pNew);
+      if( pOld ){
+        rc = sessionBindValue(p->pUpdate, i*3+1, pOld);
+      }
+      if( rc==SQLITE_OK && pNew ){
+        rc = sessionBindValue(p->pUpdate, i*3+3, pNew);
+      }
+    }
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_int(p->pUpdate, nCol*3+1, pbRetry==0 || pIter->bPatchset);
+    }
+    if( rc!=SQLITE_OK ) return rc;
+
+    /* Attempt the UPDATE. In the case of a NOTFOUND or DATA conflict,
+    ** the result will be SQLITE_OK with 0 rows modified. */
+    sqlite3_step(p->pUpdate);
+    rc = sqlite3_reset(p->pUpdate);
+
+    if( rc==SQLITE_OK && sqlite3_changes(p->db)==0 ){
+      /* A NOTFOUND or DATA error. Search the table to see if it contains
+      ** a row with a matching primary key. If so, this is a DATA conflict.
+      ** Otherwise, if there is no primary key match, it is a NOTFOUND. */
+
+      rc = sessionConflictHandler(
+          SQLITE_CHANGESET_DATA, p, pIter, xConflict, pCtx, pbRetry
+      );
+
+    }else if( (rc&0xff)==SQLITE_CONSTRAINT ){
+      /* This is always a CONSTRAINT conflict. */
+      rc = sessionConflictHandler(
+          SQLITE_CHANGESET_CONFLICT, p, pIter, xConflict, pCtx, 0
+      );
+    }
+
+  }else{
+    assert( op==SQLITE_INSERT );
+    rc = sessionBindRow(pIter, sqlite3changeset_new, nCol, 0, p->pInsert);
+    if( rc!=SQLITE_OK ) return rc;
+
+    sqlite3_step(p->pInsert);
+    rc = sqlite3_reset(p->pInsert);
+    if( (rc&0xff)==SQLITE_CONSTRAINT ){
+      rc = sessionConflictHandler(
+          SQLITE_CHANGESET_CONFLICT, p, pIter, xConflict, pCtx, pbReplace
+      );
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Attempt to apply the change that the iterator passed as the first argument
+** currently points to to the database. If a conflict is encountered, invoke
+** the conflict handler callback.
+**
+** The difference between this function and sessionApplyOne() is that this
+** function handles the case where the conflict-handler is invoked and 
+** returns SQLITE_CHANGESET_REPLACE - indicating that the change should be
+** retried in some manner.
+*/
+static int sessionApplyOneWithRetry(
+  sqlite3 *db,                    /* Apply change to "main" db of this handle */
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator to read change from */
+  SessionApplyCtx *pApply,        /* Apply context */
+  int(*xConflict)(void*, int, sqlite3_changeset_iter*),
+  void *pCtx                      /* First argument passed to xConflict */
+){
+  int bReplace = 0;
+  int bRetry = 0;
+  int rc;
+
+  rc = sessionApplyOneOp(pIter, pApply, xConflict, pCtx, &bReplace, &bRetry);
+  assert( rc==SQLITE_OK || (bRetry==0 && bReplace==0) );
+
+  /* If the bRetry flag is set, the change has not been applied due to an
+  ** SQLITE_CHANGESET_DATA problem (i.e. this is an UPDATE or DELETE and
+  ** a row with the correct PK is present in the db, but one or more other
+  ** fields do not contain the expected values) and the conflict handler 
+  ** returned SQLITE_CHANGESET_REPLACE. In this case retry the operation,
+  ** but pass NULL as the final argument so that sessionApplyOneOp() ignores
+  ** the SQLITE_CHANGESET_DATA problem.  */
+  if( bRetry ){
+    assert( pIter->op==SQLITE_UPDATE || pIter->op==SQLITE_DELETE );
+    rc = sessionApplyOneOp(pIter, pApply, xConflict, pCtx, 0, 0);
+  }
+
+  /* If the bReplace flag is set, the change is an INSERT that has not
+  ** been performed because the database already contains a row with the
+  ** specified primary key and the conflict handler returned
+  ** SQLITE_CHANGESET_REPLACE. In this case remove the conflicting row
+  ** before reattempting the INSERT.  */
+  else if( bReplace ){
+    assert( pIter->op==SQLITE_INSERT );
+    rc = sqlite3_exec(db, "SAVEPOINT replace_op", 0, 0, 0);
+    if( rc==SQLITE_OK ){
+      rc = sessionBindRow(pIter, 
+          sqlite3changeset_new, pApply->nCol, pApply->abPK, pApply->pDelete);
+      sqlite3_bind_int(pApply->pDelete, pApply->nCol+1, 1);
+    }
+    if( rc==SQLITE_OK ){
+      sqlite3_step(pApply->pDelete);
+      rc = sqlite3_reset(pApply->pDelete);
+    }
+    if( rc==SQLITE_OK ){
+      rc = sessionApplyOneOp(pIter, pApply, xConflict, pCtx, 0, 0);
+    }
+    if( rc==SQLITE_OK ){
+      rc = sqlite3_exec(db, "RELEASE replace_op", 0, 0, 0);
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Retry the changes accumulated in the pApply->constraints buffer.
+*/
+static int sessionRetryConstraints(
+  sqlite3 *db, 
+  int bPatchset,
+  const char *zTab,
+  SessionApplyCtx *pApply,
+  int(*xConflict)(void*, int, sqlite3_changeset_iter*),
+  void *pCtx                      /* First argument passed to xConflict */
+){
+  int rc = SQLITE_OK;
+
+  while( pApply->constraints.nBuf ){
+    sqlite3_changeset_iter *pIter2 = 0;
+    SessionBuffer cons = pApply->constraints;
+    memset(&pApply->constraints, 0, sizeof(SessionBuffer));
+
+    rc = sessionChangesetStart(&pIter2, 0, 0, cons.nBuf, cons.aBuf);
+    if( rc==SQLITE_OK ){
+      int nByte = 2*pApply->nCol*sizeof(sqlite3_value*);
+      int rc2;
+      pIter2->bPatchset = bPatchset;
+      pIter2->zTab = (char*)zTab;
+      pIter2->nCol = pApply->nCol;
+      pIter2->abPK = pApply->abPK;
+      sessionBufferGrow(&pIter2->tblhdr, nByte, &rc);
+      pIter2->apValue = (sqlite3_value**)pIter2->tblhdr.aBuf;
+      if( rc==SQLITE_OK ) memset(pIter2->apValue, 0, nByte);
+
+      while( rc==SQLITE_OK && SQLITE_ROW==sqlite3changeset_next(pIter2) ){
+        rc = sessionApplyOneWithRetry(db, pIter2, pApply, xConflict, pCtx);
+      }
+
+      rc2 = sqlite3changeset_finalize(pIter2);
+      if( rc==SQLITE_OK ) rc = rc2;
+    }
+    assert( pApply->bDeferConstraints || pApply->constraints.nBuf==0 );
+
+    sqlite3_free(cons.aBuf);
+    if( rc!=SQLITE_OK ) break;
+    if( pApply->constraints.nBuf>=cons.nBuf ){
+      /* No progress was made on the last round. */
+      pApply->bDeferConstraints = 0;
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Argument pIter is a changeset iterator that has been initialized, but
+** not yet passed to sqlite3changeset_next(). This function applies the 
+** changeset to the main database attached to handle "db". The supplied
+** conflict handler callback is invoked to resolve any conflicts encountered
+** while applying the change.
+*/
+static int sessionChangesetApply(
+  sqlite3 *db,                    /* Apply change to "main" db of this handle */
+  sqlite3_changeset_iter *pIter,  /* Changeset to apply */
+  int(*xFilter)(
+    void *pCtx,                   /* Copy of sixth arg to _apply() */
+    const char *zTab              /* Table name */
+  ),
+  int(*xConflict)(
+    void *pCtx,                   /* Copy of fifth arg to _apply() */
+    int eConflict,                /* DATA, MISSING, CONFLICT, CONSTRAINT */
+    sqlite3_changeset_iter *p     /* Handle describing change and conflict */
+  ),
+  void *pCtx                      /* First argument passed to xConflict */
+){
+  int schemaMismatch = 0;
+  int rc;                         /* Return code */
+  const char *zTab = 0;           /* Name of current table */
+  int nTab = 0;                   /* Result of sqlite3Strlen30(zTab) */
+  SessionApplyCtx sApply;         /* changeset_apply() context object */
+  int bPatchset;
+
+  assert( xConflict!=0 );
+
+  pIter->in.bNoDiscard = 1;
+  memset(&sApply, 0, sizeof(sApply));
+  sqlite3_mutex_enter(sqlite3_db_mutex(db));
+  rc = sqlite3_exec(db, "SAVEPOINT changeset_apply", 0, 0, 0);
+  if( rc==SQLITE_OK ){
+    rc = sqlite3_exec(db, "PRAGMA defer_foreign_keys = 1", 0, 0, 0);
+  }
+  while( rc==SQLITE_OK && SQLITE_ROW==sqlite3changeset_next(pIter) ){
+    int nCol;
+    int op;
+    const char *zNew;
+    
+    sqlite3changeset_op(pIter, &zNew, &nCol, &op, 0);
+
+    if( zTab==0 || sqlite3_strnicmp(zNew, zTab, nTab+1) ){
+      u8 *abPK;
+
+      rc = sessionRetryConstraints(
+          db, pIter->bPatchset, zTab, &sApply, xConflict, pCtx
+      );
+      if( rc!=SQLITE_OK ) break;
+
+      sqlite3_free((char*)sApply.azCol);  /* cast works around VC++ bug */
+      sqlite3_finalize(sApply.pDelete);
+      sqlite3_finalize(sApply.pUpdate); 
+      sqlite3_finalize(sApply.pInsert);
+      sqlite3_finalize(sApply.pSelect);
+      memset(&sApply, 0, sizeof(sApply));
+      sApply.db = db;
+      sApply.bDeferConstraints = 1;
+
+      /* If an xFilter() callback was specified, invoke it now. If the 
+      ** xFilter callback returns zero, skip this table. If it returns
+      ** non-zero, proceed. */
+      schemaMismatch = (xFilter && (0==xFilter(pCtx, zNew)));
+      if( schemaMismatch ){
+        zTab = sqlite3_mprintf("%s", zNew);
+        if( zTab==0 ){
+          rc = SQLITE_NOMEM;
+          break;
+        }
+        nTab = (int)strlen(zTab);
+        sApply.azCol = (const char **)zTab;
+      }else{
+        sqlite3changeset_pk(pIter, &abPK, 0);
+        rc = sessionTableInfo(
+            db, "main", zNew, &sApply.nCol, &zTab, &sApply.azCol, &sApply.abPK
+        );
+        if( rc!=SQLITE_OK ) break;
+  
+        if( sApply.nCol==0 ){
+          schemaMismatch = 1;
+          sqlite3_log(SQLITE_SCHEMA, 
+              "sqlite3changeset_apply(): no such table: %s", zTab
+          );
+        }
+        else if( sApply.nCol!=nCol ){
+          schemaMismatch = 1;
+          sqlite3_log(SQLITE_SCHEMA, 
+              "sqlite3changeset_apply(): table %s has %d columns, expected %d", 
+              zTab, sApply.nCol, nCol
+          );
+        }
+        else if( memcmp(sApply.abPK, abPK, nCol)!=0 ){
+          schemaMismatch = 1;
+          sqlite3_log(SQLITE_SCHEMA, "sqlite3changeset_apply(): "
+              "primary key mismatch for table %s", zTab
+          );
+        }
+        else if( 
+            (rc = sessionSelectRow(db, zTab, &sApply))
+         || (rc = sessionUpdateRow(db, zTab, &sApply))
+         || (rc = sessionDeleteRow(db, zTab, &sApply))
+         || (rc = sessionInsertRow(db, zTab, &sApply))
+        ){
+          break;
+        }
+        nTab = sqlite3Strlen30(zTab);
+      }
+    }
+
+    /* If there is a schema mismatch on the current table, proceed to the
+    ** next change. A log message has already been issued. */
+    if( schemaMismatch ) continue;
+
+    rc = sessionApplyOneWithRetry(db, pIter, &sApply, xConflict, pCtx);
+  }
+
+  bPatchset = pIter->bPatchset;
+  if( rc==SQLITE_OK ){
+    rc = sqlite3changeset_finalize(pIter);
+  }else{
+    sqlite3changeset_finalize(pIter);
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = sessionRetryConstraints(db, bPatchset, zTab, &sApply, xConflict, pCtx);
+  }
+
+  if( rc==SQLITE_OK ){
+    int nFk, notUsed;
+    sqlite3_db_status(db, SQLITE_DBSTATUS_DEFERRED_FKS, &nFk, &notUsed, 0);
+    if( nFk!=0 ){
+      int res = SQLITE_CHANGESET_ABORT;
+      sqlite3_changeset_iter sIter;
+      memset(&sIter, 0, sizeof(sIter));
+      sIter.nCol = nFk;
+      res = xConflict(pCtx, SQLITE_CHANGESET_FOREIGN_KEY, &sIter);
+      if( res!=SQLITE_CHANGESET_OMIT ){
+        rc = SQLITE_CONSTRAINT;
+      }
+    }
+  }
+  sqlite3_exec(db, "PRAGMA defer_foreign_keys = 0", 0, 0, 0);
+
+  if( rc==SQLITE_OK ){
+    rc = sqlite3_exec(db, "RELEASE changeset_apply", 0, 0, 0);
+  }else{
+    sqlite3_exec(db, "ROLLBACK TO changeset_apply", 0, 0, 0);
+    sqlite3_exec(db, "RELEASE changeset_apply", 0, 0, 0);
+  }
+
+  sqlite3_finalize(sApply.pInsert);
+  sqlite3_finalize(sApply.pDelete);
+  sqlite3_finalize(sApply.pUpdate);
+  sqlite3_finalize(sApply.pSelect);
+  sqlite3_free((char*)sApply.azCol);  /* cast works around VC++ bug */
+  sqlite3_free((char*)sApply.constraints.aBuf);
+  sqlite3_mutex_leave(sqlite3_db_mutex(db));
+  return rc;
+}
+
+/*
+** Apply the changeset passed via pChangeset/nChangeset to the main database
+** attached to handle "db". Invoke the supplied conflict handler callback
+** to resolve any conflicts encountered while applying the change.
+*/
+SQLITE_API int sqlite3changeset_apply(
+  sqlite3 *db,                    /* Apply change to "main" db of this handle */
+  int nChangeset,                 /* Size of changeset in bytes */
+  void *pChangeset,               /* Changeset blob */
+  int(*xFilter)(
+    void *pCtx,                   /* Copy of sixth arg to _apply() */
+    const char *zTab              /* Table name */
+  ),
+  int(*xConflict)(
+    void *pCtx,                   /* Copy of fifth arg to _apply() */
+    int eConflict,                /* DATA, MISSING, CONFLICT, CONSTRAINT */
+    sqlite3_changeset_iter *p     /* Handle describing change and conflict */
+  ),
+  void *pCtx                      /* First argument passed to xConflict */
+){
+  sqlite3_changeset_iter *pIter;  /* Iterator to skip through changeset */  
+  int rc = sqlite3changeset_start(&pIter, nChangeset, pChangeset);
+  if( rc==SQLITE_OK ){
+    rc = sessionChangesetApply(db, pIter, xFilter, xConflict, pCtx);
+  }
+  return rc;
+}
+
+/*
+** Apply the changeset passed via xInput/pIn to the main database
+** attached to handle "db". Invoke the supplied conflict handler callback
+** to resolve any conflicts encountered while applying the change.
+*/
+SQLITE_API int sqlite3changeset_apply_strm(
+  sqlite3 *db,                    /* Apply change to "main" db of this handle */
+  int (*xInput)(void *pIn, void *pData, int *pnData), /* Input function */
+  void *pIn,                                          /* First arg for xInput */
+  int(*xFilter)(
+    void *pCtx,                   /* Copy of sixth arg to _apply() */
+    const char *zTab              /* Table name */
+  ),
+  int(*xConflict)(
+    void *pCtx,                   /* Copy of sixth arg to _apply() */
+    int eConflict,                /* DATA, MISSING, CONFLICT, CONSTRAINT */
+    sqlite3_changeset_iter *p     /* Handle describing change and conflict */
+  ),
+  void *pCtx                      /* First argument passed to xConflict */
+){
+  sqlite3_changeset_iter *pIter;  /* Iterator to skip through changeset */  
+  int rc = sqlite3changeset_start_strm(&pIter, xInput, pIn);
+  if( rc==SQLITE_OK ){
+    rc = sessionChangesetApply(db, pIter, xFilter, xConflict, pCtx);
+  }
+  return rc;
+}
+
+/*
+** sqlite3_changegroup handle.
+*/
+struct sqlite3_changegroup {
+  int rc;                         /* Error code */
+  int bPatch;                     /* True to accumulate patchsets */
+  SessionTable *pList;            /* List of tables in current patch */
+};
+
+/*
+** This function is called to merge two changes to the same row together as
+** part of an sqlite3changeset_concat() operation. A new change object is
+** allocated and a pointer to it stored in *ppNew.
+*/
+static int sessionChangeMerge(
+  SessionTable *pTab,             /* Table structure */
+  int bPatchset,                  /* True for patchsets */
+  SessionChange *pExist,          /* Existing change */
+  int op2,                        /* Second change operation */
+  int bIndirect,                  /* True if second change is indirect */
+  u8 *aRec,                       /* Second change record */
+  int nRec,                       /* Number of bytes in aRec */
+  SessionChange **ppNew           /* OUT: Merged change */
+){
+  SessionChange *pNew = 0;
+
+  if( !pExist ){
+    pNew = (SessionChange *)sqlite3_malloc(sizeof(SessionChange) + nRec);
+    if( !pNew ){
+      return SQLITE_NOMEM;
+    }
+    memset(pNew, 0, sizeof(SessionChange));
+    pNew->op = op2;
+    pNew->bIndirect = bIndirect;
+    pNew->nRecord = nRec;
+    pNew->aRecord = (u8*)&pNew[1];
+    memcpy(pNew->aRecord, aRec, nRec);
+  }else{
+    int op1 = pExist->op;
+
+    /* 
+    **   op1=INSERT, op2=INSERT      ->      Unsupported. Discard op2.
+    **   op1=INSERT, op2=UPDATE      ->      INSERT.
+    **   op1=INSERT, op2=DELETE      ->      (none)
+    **
+    **   op1=UPDATE, op2=INSERT      ->      Unsupported. Discard op2.
+    **   op1=UPDATE, op2=UPDATE      ->      UPDATE.
+    **   op1=UPDATE, op2=DELETE      ->      DELETE.
+    **
+    **   op1=DELETE, op2=INSERT      ->      UPDATE.
+    **   op1=DELETE, op2=UPDATE      ->      Unsupported. Discard op2.
+    **   op1=DELETE, op2=DELETE      ->      Unsupported. Discard op2.
+    */   
+    if( (op1==SQLITE_INSERT && op2==SQLITE_INSERT)
+     || (op1==SQLITE_UPDATE && op2==SQLITE_INSERT)
+     || (op1==SQLITE_DELETE && op2==SQLITE_UPDATE)
+     || (op1==SQLITE_DELETE && op2==SQLITE_DELETE)
+    ){
+      pNew = pExist;
+    }else if( op1==SQLITE_INSERT && op2==SQLITE_DELETE ){
+      sqlite3_free(pExist);
+      assert( pNew==0 );
+    }else{
+      u8 *aExist = pExist->aRecord;
+      int nByte;
+      u8 *aCsr;
+
+      /* Allocate a new SessionChange object. Ensure that the aRecord[]
+      ** buffer of the new object is large enough to hold any record that
+      ** may be generated by combining the input records.  */
+      nByte = sizeof(SessionChange) + pExist->nRecord + nRec;
+      pNew = (SessionChange *)sqlite3_malloc(nByte);
+      if( !pNew ){
+        sqlite3_free(pExist);
+        return SQLITE_NOMEM;
+      }
+      memset(pNew, 0, sizeof(SessionChange));
+      pNew->bIndirect = (bIndirect && pExist->bIndirect);
+      aCsr = pNew->aRecord = (u8 *)&pNew[1];
+
+      if( op1==SQLITE_INSERT ){             /* INSERT + UPDATE */
+        u8 *a1 = aRec;
+        assert( op2==SQLITE_UPDATE );
+        pNew->op = SQLITE_INSERT;
+        if( bPatchset==0 ) sessionSkipRecord(&a1, pTab->nCol);
+        sessionMergeRecord(&aCsr, pTab->nCol, aExist, a1);
+      }else if( op1==SQLITE_DELETE ){       /* DELETE + INSERT */
+        assert( op2==SQLITE_INSERT );
+        pNew->op = SQLITE_UPDATE;
+        if( bPatchset ){
+          memcpy(aCsr, aRec, nRec);
+          aCsr += nRec;
+        }else{
+          if( 0==sessionMergeUpdate(&aCsr, pTab, bPatchset, aExist, 0,aRec,0) ){
+            sqlite3_free(pNew);
+            pNew = 0;
+          }
+        }
+      }else if( op2==SQLITE_UPDATE ){       /* UPDATE + UPDATE */
+        u8 *a1 = aExist;
+        u8 *a2 = aRec;
+        assert( op1==SQLITE_UPDATE );
+        if( bPatchset==0 ){
+          sessionSkipRecord(&a1, pTab->nCol);
+          sessionSkipRecord(&a2, pTab->nCol);
+        }
+        pNew->op = SQLITE_UPDATE;
+        if( 0==sessionMergeUpdate(&aCsr, pTab, bPatchset, aRec, aExist,a1,a2) ){
+          sqlite3_free(pNew);
+          pNew = 0;
+        }
+      }else{                                /* UPDATE + DELETE */
+        assert( op1==SQLITE_UPDATE && op2==SQLITE_DELETE );
+        pNew->op = SQLITE_DELETE;
+        if( bPatchset ){
+          memcpy(aCsr, aRec, nRec);
+          aCsr += nRec;
+        }else{
+          sessionMergeRecord(&aCsr, pTab->nCol, aRec, aExist);
+        }
+      }
+
+      if( pNew ){
+        pNew->nRecord = (int)(aCsr - pNew->aRecord);
+      }
+      sqlite3_free(pExist);
+    }
+  }
+
+  *ppNew = pNew;
+  return SQLITE_OK;
+}
+
+/*
+** Add all changes in the changeset traversed by the iterator passed as
+** the first argument to the changegroup hash tables.
+*/
+static int sessionChangesetToHash(
+  sqlite3_changeset_iter *pIter,   /* Iterator to read from */
+  sqlite3_changegroup *pGrp        /* Changegroup object to add changeset to */
+){
+  u8 *aRec;
+  int nRec;
+  int rc = SQLITE_OK;
+  SessionTable *pTab = 0;
+
+
+  while( SQLITE_ROW==sessionChangesetNext(pIter, &aRec, &nRec) ){
+    const char *zNew;
+    int nCol;
+    int op;
+    int iHash;
+    int bIndirect;
+    SessionChange *pChange;
+    SessionChange *pExist = 0;
+    SessionChange **pp;
+
+    if( pGrp->pList==0 ){
+      pGrp->bPatch = pIter->bPatchset;
+    }else if( pIter->bPatchset!=pGrp->bPatch ){
+      rc = SQLITE_ERROR;
+      break;
+    }
+
+    sqlite3changeset_op(pIter, &zNew, &nCol, &op, &bIndirect);
+    if( !pTab || sqlite3_stricmp(zNew, pTab->zName) ){
+      /* Search the list for a matching table */
+      int nNew = (int)strlen(zNew);
+      u8 *abPK;
+
+      sqlite3changeset_pk(pIter, &abPK, 0);
+      for(pTab = pGrp->pList; pTab; pTab=pTab->pNext){
+        if( 0==sqlite3_strnicmp(pTab->zName, zNew, nNew+1) ) break;
+      }
+      if( !pTab ){
+        SessionTable **ppTab;
+
+        pTab = sqlite3_malloc(sizeof(SessionTable) + nCol + nNew+1);
+        if( !pTab ){
+          rc = SQLITE_NOMEM;
+          break;
+        }
+        memset(pTab, 0, sizeof(SessionTable));
+        pTab->nCol = nCol;
+        pTab->abPK = (u8*)&pTab[1];
+        memcpy(pTab->abPK, abPK, nCol);
+        pTab->zName = (char*)&pTab->abPK[nCol];
+        memcpy(pTab->zName, zNew, nNew+1);
+
+        /* The new object must be linked on to the end of the list, not
+        ** simply added to the start of it. This is to ensure that the
+        ** tables within the output of sqlite3changegroup_output() are in 
+        ** the right order.  */
+        for(ppTab=&pGrp->pList; *ppTab; ppTab=&(*ppTab)->pNext);
+        *ppTab = pTab;
+      }else if( pTab->nCol!=nCol || memcmp(pTab->abPK, abPK, nCol) ){
+        rc = SQLITE_SCHEMA;
+        break;
+      }
+    }
+
+    if( sessionGrowHash(pIter->bPatchset, pTab) ){
+      rc = SQLITE_NOMEM;
+      break;
+    }
+    iHash = sessionChangeHash(
+        pTab, (pIter->bPatchset && op==SQLITE_DELETE), aRec, pTab->nChange
+    );
+
+    /* Search for existing entry. If found, remove it from the hash table. 
+    ** Code below may link it back in.
+    */
+    for(pp=&pTab->apChange[iHash]; *pp; pp=&(*pp)->pNext){
+      int bPkOnly1 = 0;
+      int bPkOnly2 = 0;
+      if( pIter->bPatchset ){
+        bPkOnly1 = (*pp)->op==SQLITE_DELETE;
+        bPkOnly2 = op==SQLITE_DELETE;
+      }
+      if( sessionChangeEqual(pTab, bPkOnly1, (*pp)->aRecord, bPkOnly2, aRec) ){
+        pExist = *pp;
+        *pp = (*pp)->pNext;
+        pTab->nEntry--;
+        break;
+      }
+    }
+
+    rc = sessionChangeMerge(pTab, 
+        pIter->bPatchset, pExist, op, bIndirect, aRec, nRec, &pChange
+    );
+    if( rc ) break;
+    if( pChange ){
+      pChange->pNext = pTab->apChange[iHash];
+      pTab->apChange[iHash] = pChange;
+      pTab->nEntry++;
+    }
+  }
+
+  if( rc==SQLITE_OK ) rc = pIter->rc;
+  return rc;
+}
+
+/*
+** Serialize a changeset (or patchset) based on all changesets (or patchsets)
+** added to the changegroup object passed as the first argument.
+**
+** If xOutput is not NULL, then the changeset/patchset is returned to the
+** user via one or more calls to xOutput, as with the other streaming
+** interfaces. 
+**
+** Or, if xOutput is NULL, then (*ppOut) is populated with a pointer to a
+** buffer containing the output changeset before this function returns. In
+** this case (*pnOut) is set to the size of the output buffer in bytes. It
+** is the responsibility of the caller to free the output buffer using
+** sqlite3_free() when it is no longer required.
+**
+** If successful, SQLITE_OK is returned. Or, if an error occurs, an SQLite
+** error code. If an error occurs and xOutput is NULL, (*ppOut) and (*pnOut)
+** are both set to 0 before returning.
+*/
+static int sessionChangegroupOutput(
+  sqlite3_changegroup *pGrp,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut,
+  int *pnOut,
+  void **ppOut
+){
+  int rc = SQLITE_OK;
+  SessionBuffer buf = {0, 0, 0};
+  SessionTable *pTab;
+  assert( xOutput==0 || (ppOut==0 && pnOut==0) );
+
+  /* Create the serialized output changeset based on the contents of the
+  ** hash tables attached to the SessionTable objects in list p->pList. 
+  */
+  for(pTab=pGrp->pList; rc==SQLITE_OK && pTab; pTab=pTab->pNext){
+    int i;
+    if( pTab->nEntry==0 ) continue;
+
+    sessionAppendTableHdr(&buf, pGrp->bPatch, pTab, &rc);
+    for(i=0; i<pTab->nChange; i++){
+      SessionChange *p;
+      for(p=pTab->apChange[i]; p; p=p->pNext){
+        sessionAppendByte(&buf, p->op, &rc);
+        sessionAppendByte(&buf, p->bIndirect, &rc);
+        sessionAppendBlob(&buf, p->aRecord, p->nRecord, &rc);
+      }
+    }
+
+    if( rc==SQLITE_OK && xOutput && buf.nBuf>=SESSIONS_STRM_CHUNK_SIZE ){
+      rc = xOutput(pOut, buf.aBuf, buf.nBuf);
+      buf.nBuf = 0;
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    if( xOutput ){
+      if( buf.nBuf>0 ) rc = xOutput(pOut, buf.aBuf, buf.nBuf);
+    }else{
+      *ppOut = buf.aBuf;
+      *pnOut = buf.nBuf;
+      buf.aBuf = 0;
+    }
+  }
+  sqlite3_free(buf.aBuf);
+
+  return rc;
+}
+
+/*
+** Allocate a new, empty, sqlite3_changegroup.
+*/
+SQLITE_API int sqlite3changegroup_new(sqlite3_changegroup **pp){
+  int rc = SQLITE_OK;             /* Return code */
+  sqlite3_changegroup *p;         /* New object */
+  p = (sqlite3_changegroup*)sqlite3_malloc(sizeof(sqlite3_changegroup));
+  if( p==0 ){
+    rc = SQLITE_NOMEM;
+  }else{
+    memset(p, 0, sizeof(sqlite3_changegroup));
+  }
+  *pp = p;
+  return rc;
+}
+
+/*
+** Add the changeset currently stored in buffer pData, size nData bytes,
+** to changeset-group p.
+*/
+SQLITE_API int sqlite3changegroup_add(sqlite3_changegroup *pGrp, int nData, void *pData){
+  sqlite3_changeset_iter *pIter;  /* Iterator opened on pData/nData */
+  int rc;                         /* Return code */
+
+  rc = sqlite3changeset_start(&pIter, nData, pData);
+  if( rc==SQLITE_OK ){
+    rc = sessionChangesetToHash(pIter, pGrp);
+  }
+  sqlite3changeset_finalize(pIter);
+  return rc;
+}
+
+/*
+** Obtain a buffer containing a changeset representing the concatenation
+** of all changesets added to the group so far.
+*/
+SQLITE_API int sqlite3changegroup_output(
+    sqlite3_changegroup *pGrp,
+    int *pnData,
+    void **ppData
+){
+  return sessionChangegroupOutput(pGrp, 0, 0, pnData, ppData);
+}
+
+/*
+** Streaming versions of changegroup_add().
+*/
+SQLITE_API int sqlite3changegroup_add_strm(
+  sqlite3_changegroup *pGrp,
+  int (*xInput)(void *pIn, void *pData, int *pnData),
+  void *pIn
+){
+  sqlite3_changeset_iter *pIter;  /* Iterator opened on pData/nData */
+  int rc;                         /* Return code */
+
+  rc = sqlite3changeset_start_strm(&pIter, xInput, pIn);
+  if( rc==SQLITE_OK ){
+    rc = sessionChangesetToHash(pIter, pGrp);
+  }
+  sqlite3changeset_finalize(pIter);
+  return rc;
+}
+
+/*
+** Streaming versions of changegroup_output().
+*/
+SQLITE_API int sqlite3changegroup_output_strm(
+  sqlite3_changegroup *pGrp,
+  int (*xOutput)(void *pOut, const void *pData, int nData), 
+  void *pOut
+){
+  return sessionChangegroupOutput(pGrp, xOutput, pOut, 0, 0);
+}
+
+/*
+** Delete a changegroup object.
+*/
+SQLITE_API void sqlite3changegroup_delete(sqlite3_changegroup *pGrp){
+  if( pGrp ){
+    sessionDeleteTable(pGrp->pList);
+    sqlite3_free(pGrp);
+  }
+}
+
+/* 
+** Combine two changesets together.
+*/
+SQLITE_API int sqlite3changeset_concat(
+  int nLeft,                      /* Number of bytes in lhs input */
+  void *pLeft,                    /* Lhs input changeset */
+  int nRight                      /* Number of bytes in rhs input */,
+  void *pRight,                   /* Rhs input changeset */
+  int *pnOut,                     /* OUT: Number of bytes in output changeset */
+  void **ppOut                    /* OUT: changeset (left <concat> right) */
+){
+  sqlite3_changegroup *pGrp;
+  int rc;
+
+  rc = sqlite3changegroup_new(&pGrp);
+  if( rc==SQLITE_OK ){
+    rc = sqlite3changegroup_add(pGrp, nLeft, pLeft);
+  }
+  if( rc==SQLITE_OK ){
+    rc = sqlite3changegroup_add(pGrp, nRight, pRight);
+  }
+  if( rc==SQLITE_OK ){
+    rc = sqlite3changegroup_output(pGrp, pnOut, ppOut);
+  }
+  sqlite3changegroup_delete(pGrp);
+
+  return rc;
+}
+
+/*
+** Streaming version of sqlite3changeset_concat().
+*/
+SQLITE_API int sqlite3changeset_concat_strm(
+  int (*xInputA)(void *pIn, void *pData, int *pnData),
+  void *pInA,
+  int (*xInputB)(void *pIn, void *pData, int *pnData),
+  void *pInB,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut
+){
+  sqlite3_changegroup *pGrp;
+  int rc;
+
+  rc = sqlite3changegroup_new(&pGrp);
+  if( rc==SQLITE_OK ){
+    rc = sqlite3changegroup_add_strm(pGrp, xInputA, pInA);
+  }
+  if( rc==SQLITE_OK ){
+    rc = sqlite3changegroup_add_strm(pGrp, xInputB, pInB);
+  }
+  if( rc==SQLITE_OK ){
+    rc = sqlite3changegroup_output_strm(pGrp, xOutput, pOut);
+  }
+  sqlite3changegroup_delete(pGrp);
+
+  return rc;
+}
+
+#endif /* SQLITE_ENABLE_SESSION && SQLITE_ENABLE_PREUPDATE_HOOK */
+
+/************** End of sqlite3session.c **************************************/
+/************** Begin file json1.c *******************************************/
+/*
+** 2015-08-12
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This SQLite extension implements JSON functions.  The interface is
+** modeled after MySQL JSON functions:
+**
+**     https://dev.mysql.com/doc/refman/5.7/en/json.html
+**
+** For the time being, all JSON is stored as pure text.  (We might add
+** a JSONB type in the future which stores a binary encoding of JSON in
+** a BLOB, but there is no support for JSONB in the current implementation.
+** This implementation parses JSON text at 250 MB/s, so it is hard to see
+** how JSONB might improve on that.)
+*/
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_JSON1)
+#if !defined(_SQLITEINT_H_)
+/* #include "sqlite3ext.h" */
+#endif
+SQLITE_EXTENSION_INIT1
+/* #include <assert.h> */
+/* #include <string.h> */
+/* #include <stdlib.h> */
+/* #include <stdarg.h> */
+
+/* Mark a function parameter as unused, to suppress nuisance compiler
+** warnings. */
+#ifndef UNUSED_PARAM
+# define UNUSED_PARAM(X)  (void)(X)
+#endif
+
+#ifndef LARGEST_INT64
+# define LARGEST_INT64  (0xffffffff|(((sqlite3_int64)0x7fffffff)<<32))
+# define SMALLEST_INT64 (((sqlite3_int64)-1) - LARGEST_INT64)
+#endif
+
+/*
+** Versions of isspace(), isalnum() and isdigit() to which it is safe
+** to pass signed char values.
+*/
+#ifdef sqlite3Isdigit
+   /* Use the SQLite core versions if this routine is part of the
+   ** SQLite amalgamation */
+#  define safe_isdigit(x)  sqlite3Isdigit(x)
+#  define safe_isalnum(x)  sqlite3Isalnum(x)
+#  define safe_isxdigit(x) sqlite3Isxdigit(x)
+#else
+   /* Use the standard library for separate compilation */
+#include <ctype.h>  /* amalgamator: keep */
+#  define safe_isdigit(x)  isdigit((unsigned char)(x))
+#  define safe_isalnum(x)  isalnum((unsigned char)(x))
+#  define safe_isxdigit(x) isxdigit((unsigned char)(x))
+#endif
+
+/*
+** Growing our own isspace() routine this way is twice as fast as
+** the library isspace() function, resulting in a 7% overall performance
+** increase for the parser.  (Ubuntu14.10 gcc 4.8.4 x64 with -Os).
+*/
+static const char jsonIsSpace[] = {
+  0, 0, 0, 0, 0, 0, 0, 0,     0, 1, 1, 0, 0, 1, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
+  1, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
+};
+#define safe_isspace(x) (jsonIsSpace[(unsigned char)x])
+
+#ifndef SQLITE_AMALGAMATION
+  /* Unsigned integer types.  These are already defined in the sqliteInt.h,
+  ** but the definitions need to be repeated for separate compilation. */
+  typedef sqlite3_uint64 u64;
+  typedef unsigned int u32;
+  typedef unsigned char u8;
+#endif
+
+/* Objects */
+typedef struct JsonString JsonString;
+typedef struct JsonNode JsonNode;
+typedef struct JsonParse JsonParse;
+
+/* An instance of this object represents a JSON string
+** under construction.  Really, this is a generic string accumulator
+** that can be and is used to create strings other than JSON.
+*/
+struct JsonString {
+  sqlite3_context *pCtx;   /* Function context - put error messages here */
+  char *zBuf;              /* Append JSON content here */
+  u64 nAlloc;              /* Bytes of storage available in zBuf[] */
+  u64 nUsed;               /* Bytes of zBuf[] currently used */
+  u8 bStatic;              /* True if zBuf is static space */
+  u8 bErr;                 /* True if an error has been encountered */
+  char zSpace[100];        /* Initial static space */
+};
+
+/* JSON type values
+*/
+#define JSON_NULL     0
+#define JSON_TRUE     1
+#define JSON_FALSE    2
+#define JSON_INT      3
+#define JSON_REAL     4
+#define JSON_STRING   5
+#define JSON_ARRAY    6
+#define JSON_OBJECT   7
+
+/* The "subtype" set for JSON values */
+#define JSON_SUBTYPE  74    /* Ascii for "J" */
+
+/*
+** Names of the various JSON types:
+*/
+static const char * const jsonType[] = {
+  "null", "true", "false", "integer", "real", "text", "array", "object"
+};
+
+/* Bit values for the JsonNode.jnFlag field
+*/
+#define JNODE_RAW     0x01         /* Content is raw, not JSON encoded */
+#define JNODE_ESCAPE  0x02         /* Content is text with \ escapes */
+#define JNODE_REMOVE  0x04         /* Do not output */
+#define JNODE_REPLACE 0x08         /* Replace with JsonNode.iVal */
+#define JNODE_APPEND  0x10         /* More ARRAY/OBJECT entries at u.iAppend */
+#define JNODE_LABEL   0x20         /* Is a label of an object */
+
+
+/* A single node of parsed JSON
+*/
+struct JsonNode {
+  u8 eType;              /* One of the JSON_ type values */
+  u8 jnFlags;            /* JNODE flags */
+  u8 iVal;               /* Replacement value when JNODE_REPLACE */
+  u32 n;                 /* Bytes of content, or number of sub-nodes */
+  union {
+    const char *zJContent; /* Content for INT, REAL, and STRING */
+    u32 iAppend;           /* More terms for ARRAY and OBJECT */
+    u32 iKey;              /* Key for ARRAY objects in json_tree() */
+  } u;
+};
+
+/* A completely parsed JSON string
+*/
+struct JsonParse {
+  u32 nNode;         /* Number of slots of aNode[] used */
+  u32 nAlloc;        /* Number of slots of aNode[] allocated */
+  JsonNode *aNode;   /* Array of nodes containing the parse */
+  const char *zJson; /* Original JSON string */
+  u32 *aUp;          /* Index of parent of each node */
+  u8 oom;            /* Set to true if out of memory */
+  u8 nErr;           /* Number of errors seen */
+};
+
+/**************************************************************************
+** Utility routines for dealing with JsonString objects
+**************************************************************************/
+
+/* Set the JsonString object to an empty string
+*/
+static void jsonZero(JsonString *p){
+  p->zBuf = p->zSpace;
+  p->nAlloc = sizeof(p->zSpace);
+  p->nUsed = 0;
+  p->bStatic = 1;
+}
+
+/* Initialize the JsonString object
+*/
+static void jsonInit(JsonString *p, sqlite3_context *pCtx){
+  p->pCtx = pCtx;
+  p->bErr = 0;
+  jsonZero(p);
+}
+
+
+/* Free all allocated memory and reset the JsonString object back to its
+** initial state.
+*/
+static void jsonReset(JsonString *p){
+  if( !p->bStatic ) sqlite3_free(p->zBuf);
+  jsonZero(p);
+}
+
+
+/* Report an out-of-memory (OOM) condition 
+*/
+static void jsonOom(JsonString *p){
+  p->bErr = 1;
+  sqlite3_result_error_nomem(p->pCtx);
+  jsonReset(p);
+}
+
+/* Enlarge pJson->zBuf so that it can hold at least N more bytes.
+** Return zero on success.  Return non-zero on an OOM error
+*/
+static int jsonGrow(JsonString *p, u32 N){
+  u64 nTotal = N<p->nAlloc ? p->nAlloc*2 : p->nAlloc+N+10;
+  char *zNew;
+  if( p->bStatic ){
+    if( p->bErr ) return 1;
+    zNew = sqlite3_malloc64(nTotal);
+    if( zNew==0 ){
+      jsonOom(p);
+      return SQLITE_NOMEM;
+    }
+    memcpy(zNew, p->zBuf, (size_t)p->nUsed);
+    p->zBuf = zNew;
+    p->bStatic = 0;
+  }else{
+    zNew = sqlite3_realloc64(p->zBuf, nTotal);
+    if( zNew==0 ){
+      jsonOom(p);
+      return SQLITE_NOMEM;
+    }
+    p->zBuf = zNew;
+  }
+  p->nAlloc = nTotal;
+  return SQLITE_OK;
+}
+
+/* Append N bytes from zIn onto the end of the JsonString string.
+*/
+static void jsonAppendRaw(JsonString *p, const char *zIn, u32 N){
+  if( (N+p->nUsed >= p->nAlloc) && jsonGrow(p,N)!=0 ) return;
+  memcpy(p->zBuf+p->nUsed, zIn, N);
+  p->nUsed += N;
+}
+
+/* Append formatted text (not to exceed N bytes) to the JsonString.
+*/
+static void jsonPrintf(int N, JsonString *p, const char *zFormat, ...){
+  va_list ap;
+  if( (p->nUsed + N >= p->nAlloc) && jsonGrow(p, N) ) return;
+  va_start(ap, zFormat);
+  sqlite3_vsnprintf(N, p->zBuf+p->nUsed, zFormat, ap);
+  va_end(ap);
+  p->nUsed += (int)strlen(p->zBuf+p->nUsed);
+}
+
+/* Append a single character
+*/
+static void jsonAppendChar(JsonString *p, char c){
+  if( p->nUsed>=p->nAlloc && jsonGrow(p,1)!=0 ) return;
+  p->zBuf[p->nUsed++] = c;
+}
+
+/* Append a comma separator to the output buffer, if the previous
+** character is not '[' or '{'.
+*/
+static void jsonAppendSeparator(JsonString *p){
+  char c;
+  if( p->nUsed==0 ) return;
+  c = p->zBuf[p->nUsed-1];
+  if( c!='[' && c!='{' ) jsonAppendChar(p, ',');
+}
+
+/* Append the N-byte string in zIn to the end of the JsonString string
+** under construction.  Enclose the string in "..." and escape
+** any double-quotes or backslash characters contained within the
+** string.
+*/
+static void jsonAppendString(JsonString *p, const char *zIn, u32 N){
+  u32 i;
+  if( (N+p->nUsed+2 >= p->nAlloc) && jsonGrow(p,N+2)!=0 ) return;
+  p->zBuf[p->nUsed++] = '"';
+  for(i=0; i<N; i++){
+    unsigned char c = ((unsigned const char*)zIn)[i];
+    if( c=='"' || c=='\\' ){
+      json_simple_escape:
+      if( (p->nUsed+N+3-i > p->nAlloc) && jsonGrow(p,N+3-i)!=0 ) return;
+      p->zBuf[p->nUsed++] = '\\';
+    }else if( c<=0x1f ){
+      static const char aSpecial[] = {
+         0, 0, 0, 0, 0, 0, 0, 0, 'b', 't', 'n', 0, 'f', 'r', 0, 0,
+         0, 0, 0, 0, 0, 0, 0, 0,   0,   0,   0, 0,   0,   0, 0, 0
+      };
+      assert( sizeof(aSpecial)==32 );
+      assert( aSpecial['\b']=='b' );
+      assert( aSpecial['\f']=='f' );
+      assert( aSpecial['\n']=='n' );
+      assert( aSpecial['\r']=='r' );
+      assert( aSpecial['\t']=='t' );
+      if( aSpecial[c] ){
+        c = aSpecial[c];
+        goto json_simple_escape;
+      }
+      if( (p->nUsed+N+7+i > p->nAlloc) && jsonGrow(p,N+7-i)!=0 ) return;
+      p->zBuf[p->nUsed++] = '\\';
+      p->zBuf[p->nUsed++] = 'u';
+      p->zBuf[p->nUsed++] = '0';
+      p->zBuf[p->nUsed++] = '0';
+      p->zBuf[p->nUsed++] = '0' + (c>>4);
+      c = "0123456789abcdef"[c&0xf];
+    }
+    p->zBuf[p->nUsed++] = c;
+  }
+  p->zBuf[p->nUsed++] = '"';
+  assert( p->nUsed<p->nAlloc );
+}
+
+/*
+** Append a function parameter value to the JSON string under 
+** construction.
+*/
+static void jsonAppendValue(
+  JsonString *p,                 /* Append to this JSON string */
+  sqlite3_value *pValue          /* Value to append */
+){
+  switch( sqlite3_value_type(pValue) ){
+    case SQLITE_NULL: {
+      jsonAppendRaw(p, "null", 4);
+      break;
+    }
+    case SQLITE_INTEGER:
+    case SQLITE_FLOAT: {
+      const char *z = (const char*)sqlite3_value_text(pValue);
+      u32 n = (u32)sqlite3_value_bytes(pValue);
+      jsonAppendRaw(p, z, n);
+      break;
+    }
+    case SQLITE_TEXT: {
+      const char *z = (const char*)sqlite3_value_text(pValue);
+      u32 n = (u32)sqlite3_value_bytes(pValue);
+      if( sqlite3_value_subtype(pValue)==JSON_SUBTYPE ){
+        jsonAppendRaw(p, z, n);
+      }else{
+        jsonAppendString(p, z, n);
+      }
+      break;
+    }
+    default: {
+      if( p->bErr==0 ){
+        sqlite3_result_error(p->pCtx, "JSON cannot hold BLOB values", -1);
+        p->bErr = 2;
+        jsonReset(p);
+      }
+      break;
+    }
+  }
+}
+
+
+/* Make the JSON in p the result of the SQL function.
+*/
+static void jsonResult(JsonString *p){
+  if( p->bErr==0 ){
+    sqlite3_result_text64(p->pCtx, p->zBuf, p->nUsed, 
+                          p->bStatic ? SQLITE_TRANSIENT : sqlite3_free,
+                          SQLITE_UTF8);
+    jsonZero(p);
+  }
+  assert( p->bStatic );
+}
+
+/**************************************************************************
+** Utility routines for dealing with JsonNode and JsonParse objects
+**************************************************************************/
+
+/*
+** Return the number of consecutive JsonNode slots need to represent
+** the parsed JSON at pNode.  The minimum answer is 1.  For ARRAY and
+** OBJECT types, the number might be larger.
+**
+** Appended elements are not counted.  The value returned is the number
+** by which the JsonNode counter should increment in order to go to the
+** next peer value.
+*/
+static u32 jsonNodeSize(JsonNode *pNode){
+  return pNode->eType>=JSON_ARRAY ? pNode->n+1 : 1;
+}
+
+/*
+** Reclaim all memory allocated by a JsonParse object.  But do not
+** delete the JsonParse object itself.
+*/
+static void jsonParseReset(JsonParse *pParse){
+  sqlite3_free(pParse->aNode);
+  pParse->aNode = 0;
+  pParse->nNode = 0;
+  pParse->nAlloc = 0;
+  sqlite3_free(pParse->aUp);
+  pParse->aUp = 0;
+}
+
+/*
+** Convert the JsonNode pNode into a pure JSON string and
+** append to pOut.  Subsubstructure is also included.  Return
+** the number of JsonNode objects that are encoded.
+*/
+static void jsonRenderNode(
+  JsonNode *pNode,               /* The node to render */
+  JsonString *pOut,              /* Write JSON here */
+  sqlite3_value **aReplace       /* Replacement values */
+){
+  switch( pNode->eType ){
+    default: {
+      assert( pNode->eType==JSON_NULL );
+      jsonAppendRaw(pOut, "null", 4);
+      break;
+    }
+    case JSON_TRUE: {
+      jsonAppendRaw(pOut, "true", 4);
+      break;
+    }
+    case JSON_FALSE: {
+      jsonAppendRaw(pOut, "false", 5);
+      break;
+    }
+    case JSON_STRING: {
+      if( pNode->jnFlags & JNODE_RAW ){
+        jsonAppendString(pOut, pNode->u.zJContent, pNode->n);
+        break;
+      }
+      /* Fall through into the next case */
+    }
+    case JSON_REAL:
+    case JSON_INT: {
+      jsonAppendRaw(pOut, pNode->u.zJContent, pNode->n);
+      break;
+    }
+    case JSON_ARRAY: {
+      u32 j = 1;
+      jsonAppendChar(pOut, '[');
+      for(;;){
+        while( j<=pNode->n ){
+          if( pNode[j].jnFlags & (JNODE_REMOVE|JNODE_REPLACE) ){
+            if( pNode[j].jnFlags & JNODE_REPLACE ){
+              jsonAppendSeparator(pOut);
+              jsonAppendValue(pOut, aReplace[pNode[j].iVal]);
+            }
+          }else{
+            jsonAppendSeparator(pOut);
+            jsonRenderNode(&pNode[j], pOut, aReplace);
+          }
+          j += jsonNodeSize(&pNode[j]);
+        }
+        if( (pNode->jnFlags & JNODE_APPEND)==0 ) break;
+        pNode = &pNode[pNode->u.iAppend];
+        j = 1;
+      }
+      jsonAppendChar(pOut, ']');
+      break;
+    }
+    case JSON_OBJECT: {
+      u32 j = 1;
+      jsonAppendChar(pOut, '{');
+      for(;;){
+        while( j<=pNode->n ){
+          if( (pNode[j+1].jnFlags & JNODE_REMOVE)==0 ){
+            jsonAppendSeparator(pOut);
+            jsonRenderNode(&pNode[j], pOut, aReplace);
+            jsonAppendChar(pOut, ':');
+            if( pNode[j+1].jnFlags & JNODE_REPLACE ){
+              jsonAppendValue(pOut, aReplace[pNode[j+1].iVal]);
+            }else{
+              jsonRenderNode(&pNode[j+1], pOut, aReplace);
+            }
+          }
+          j += 1 + jsonNodeSize(&pNode[j+1]);
+        }
+        if( (pNode->jnFlags & JNODE_APPEND)==0 ) break;
+        pNode = &pNode[pNode->u.iAppend];
+        j = 1;
+      }
+      jsonAppendChar(pOut, '}');
+      break;
+    }
+  }
+}
+
+/*
+** Return a JsonNode and all its descendents as a JSON string.
+*/
+static void jsonReturnJson(
+  JsonNode *pNode,            /* Node to return */
+  sqlite3_context *pCtx,      /* Return value for this function */
+  sqlite3_value **aReplace    /* Array of replacement values */
+){
+  JsonString s;
+  jsonInit(&s, pCtx);
+  jsonRenderNode(pNode, &s, aReplace);
+  jsonResult(&s);
+  sqlite3_result_subtype(pCtx, JSON_SUBTYPE);
+}
+
+/*
+** Make the JsonNode the return value of the function.
+*/
+static void jsonReturn(
+  JsonNode *pNode,            /* Node to return */
+  sqlite3_context *pCtx,      /* Return value for this function */
+  sqlite3_value **aReplace    /* Array of replacement values */
+){
+  switch( pNode->eType ){
+    default: {
+      assert( pNode->eType==JSON_NULL );
+      sqlite3_result_null(pCtx);
+      break;
+    }
+    case JSON_TRUE: {
+      sqlite3_result_int(pCtx, 1);
+      break;
+    }
+    case JSON_FALSE: {
+      sqlite3_result_int(pCtx, 0);
+      break;
+    }
+    case JSON_INT: {
+      sqlite3_int64 i = 0;
+      const char *z = pNode->u.zJContent;
+      if( z[0]=='-' ){ z++; }
+      while( z[0]>='0' && z[0]<='9' ){
+        unsigned v = *(z++) - '0';
+        if( i>=LARGEST_INT64/10 ){
+          if( i>LARGEST_INT64/10 ) goto int_as_real;
+          if( z[0]>='0' && z[0]<='9' ) goto int_as_real;
+          if( v==9 ) goto int_as_real;
+          if( v==8 ){
+            if( pNode->u.zJContent[0]=='-' ){
+              sqlite3_result_int64(pCtx, SMALLEST_INT64);
+              goto int_done;
+            }else{
+              goto int_as_real;
+            }
+          }
+        }
+        i = i*10 + v;
+      }
+      if( pNode->u.zJContent[0]=='-' ){ i = -i; }
+      sqlite3_result_int64(pCtx, i);
+      int_done:
+      break;
+      int_as_real: /* fall through to real */;
+    }
+    case JSON_REAL: {
+      double r;
+#ifdef SQLITE_AMALGAMATION
+      const char *z = pNode->u.zJContent;
+      sqlite3AtoF(z, &r, sqlite3Strlen30(z), SQLITE_UTF8);
+#else
+      r = strtod(pNode->u.zJContent, 0);
+#endif
+      sqlite3_result_double(pCtx, r);
+      break;
+    }
+    case JSON_STRING: {
+#if 0 /* Never happens because JNODE_RAW is only set by json_set(),
+      ** json_insert() and json_replace() and those routines do not
+      ** call jsonReturn() */
+      if( pNode->jnFlags & JNODE_RAW ){
+        sqlite3_result_text(pCtx, pNode->u.zJContent, pNode->n,
+                            SQLITE_TRANSIENT);
+      }else 
+#endif
+      assert( (pNode->jnFlags & JNODE_RAW)==0 );
+      if( (pNode->jnFlags & JNODE_ESCAPE)==0 ){
+        /* JSON formatted without any backslash-escapes */
+        sqlite3_result_text(pCtx, pNode->u.zJContent+1, pNode->n-2,
+                            SQLITE_TRANSIENT);
+      }else{
+        /* Translate JSON formatted string into raw text */
+        u32 i;
+        u32 n = pNode->n;
+        const char *z = pNode->u.zJContent;
+        char *zOut;
+        u32 j;
+        zOut = sqlite3_malloc( n+1 );
+        if( zOut==0 ){
+          sqlite3_result_error_nomem(pCtx);
+          break;
+        }
+        for(i=1, j=0; i<n-1; i++){
+          char c = z[i];
+          if( c!='\\' ){
+            zOut[j++] = c;
+          }else{
+            c = z[++i];
+            if( c=='u' ){
+              u32 v = 0, k;
+              for(k=0; k<4 && i<n-2; i++, k++){
+                c = z[i+1];
+                if( c>='0' && c<='9' ) v = v*16 + c - '0';
+                else if( c>='A' && c<='F' ) v = v*16 + c - 'A' + 10;
+                else if( c>='a' && c<='f' ) v = v*16 + c - 'a' + 10;
+                else break;
+              }
+              if( v==0 ) break;
+              if( v<=0x7f ){
+                zOut[j++] = (char)v;
+              }else if( v<=0x7ff ){
+                zOut[j++] = (char)(0xc0 | (v>>6));
+                zOut[j++] = 0x80 | (v&0x3f);
+              }else{
+                zOut[j++] = (char)(0xe0 | (v>>12));
+                zOut[j++] = 0x80 | ((v>>6)&0x3f);
+                zOut[j++] = 0x80 | (v&0x3f);
+              }
+            }else{
+              if( c=='b' ){
+                c = '\b';
+              }else if( c=='f' ){
+                c = '\f';
+              }else if( c=='n' ){
+                c = '\n';
+              }else if( c=='r' ){
+                c = '\r';
+              }else if( c=='t' ){
+                c = '\t';
+              }
+              zOut[j++] = c;
+            }
+          }
+        }
+        zOut[j] = 0;
+        sqlite3_result_text(pCtx, zOut, j, sqlite3_free);
+      }
+      break;
+    }
+    case JSON_ARRAY:
+    case JSON_OBJECT: {
+      jsonReturnJson(pNode, pCtx, aReplace);
+      break;
+    }
+  }
+}
+
+/* Forward reference */
+static int jsonParseAddNode(JsonParse*,u32,u32,const char*);
+
+/*
+** A macro to hint to the compiler that a function should not be
+** inlined.
+*/
+#if defined(__GNUC__)
+#  define JSON_NOINLINE  __attribute__((noinline))
+#elif defined(_MSC_VER) && _MSC_VER>=1310
+#  define JSON_NOINLINE  __declspec(noinline)
+#else
+#  define JSON_NOINLINE
+#endif
+
+
+static JSON_NOINLINE int jsonParseAddNodeExpand(
+  JsonParse *pParse,        /* Append the node to this object */
+  u32 eType,                /* Node type */
+  u32 n,                    /* Content size or sub-node count */
+  const char *zContent      /* Content */
+){
+  u32 nNew;
+  JsonNode *pNew;
+  assert( pParse->nNode>=pParse->nAlloc );
+  if( pParse->oom ) return -1;
+  nNew = pParse->nAlloc*2 + 10;
+  pNew = sqlite3_realloc(pParse->aNode, sizeof(JsonNode)*nNew);
+  if( pNew==0 ){
+    pParse->oom = 1;
+    return -1;
+  }
+  pParse->nAlloc = nNew;
+  pParse->aNode = pNew;
+  assert( pParse->nNode<pParse->nAlloc );
+  return jsonParseAddNode(pParse, eType, n, zContent);
+}
+
+/*
+** Create a new JsonNode instance based on the arguments and append that
+** instance to the JsonParse.  Return the index in pParse->aNode[] of the
+** new node, or -1 if a memory allocation fails.
+*/
+static int jsonParseAddNode(
+  JsonParse *pParse,        /* Append the node to this object */
+  u32 eType,                /* Node type */
+  u32 n,                    /* Content size or sub-node count */
+  const char *zContent      /* Content */
+){
+  JsonNode *p;
+  if( pParse->nNode>=pParse->nAlloc ){
+    return jsonParseAddNodeExpand(pParse, eType, n, zContent);
+  }
+  p = &pParse->aNode[pParse->nNode];
+  p->eType = (u8)eType;
+  p->jnFlags = 0;
+  p->iVal = 0;
+  p->n = n;
+  p->u.zJContent = zContent;
+  return pParse->nNode++;
+}
+
+/*
+** Return true if z[] begins with 4 (or more) hexadecimal digits
+*/
+static int jsonIs4Hex(const char *z){
+  int i;
+  for(i=0; i<4; i++) if( !safe_isxdigit(z[i]) ) return 0;
+  return 1;
+}
+
+/*
+** Parse a single JSON value which begins at pParse->zJson[i].  Return the
+** index of the first character past the end of the value parsed.
+**
+** Return negative for a syntax error.  Special cases:  return -2 if the
+** first non-whitespace character is '}' and return -3 if the first
+** non-whitespace character is ']'.
+*/
+static int jsonParseValue(JsonParse *pParse, u32 i){
+  char c;
+  u32 j;
+  int iThis;
+  int x;
+  JsonNode *pNode;
+  while( safe_isspace(pParse->zJson[i]) ){ i++; }
+  if( (c = pParse->zJson[i])=='{' ){
+    /* Parse object */
+    iThis = jsonParseAddNode(pParse, JSON_OBJECT, 0, 0);
+    if( iThis<0 ) return -1;
+    for(j=i+1;;j++){
+      while( safe_isspace(pParse->zJson[j]) ){ j++; }
+      x = jsonParseValue(pParse, j);
+      if( x<0 ){
+        if( x==(-2) && pParse->nNode==(u32)iThis+1 ) return j+1;
+        return -1;
+      }
+      if( pParse->oom ) return -1;
+      pNode = &pParse->aNode[pParse->nNode-1];
+      if( pNode->eType!=JSON_STRING ) return -1;
+      pNode->jnFlags |= JNODE_LABEL;
+      j = x;
+      while( safe_isspace(pParse->zJson[j]) ){ j++; }
+      if( pParse->zJson[j]!=':' ) return -1;
+      j++;
+      x = jsonParseValue(pParse, j);
+      if( x<0 ) return -1;
+      j = x;
+      while( safe_isspace(pParse->zJson[j]) ){ j++; }
+      c = pParse->zJson[j];
+      if( c==',' ) continue;
+      if( c!='}' ) return -1;
+      break;
+    }
+    pParse->aNode[iThis].n = pParse->nNode - (u32)iThis - 1;
+    return j+1;
+  }else if( c=='[' ){
+    /* Parse array */
+    iThis = jsonParseAddNode(pParse, JSON_ARRAY, 0, 0);
+    if( iThis<0 ) return -1;
+    for(j=i+1;;j++){
+      while( safe_isspace(pParse->zJson[j]) ){ j++; }
+      x = jsonParseValue(pParse, j);
+      if( x<0 ){
+        if( x==(-3) && pParse->nNode==(u32)iThis+1 ) return j+1;
+        return -1;
+      }
+      j = x;
+      while( safe_isspace(pParse->zJson[j]) ){ j++; }
+      c = pParse->zJson[j];
+      if( c==',' ) continue;
+      if( c!=']' ) return -1;
+      break;
+    }
+    pParse->aNode[iThis].n = pParse->nNode - (u32)iThis - 1;
+    return j+1;
+  }else if( c=='"' ){
+    /* Parse string */
+    u8 jnFlags = 0;
+    j = i+1;
+    for(;;){
+      c = pParse->zJson[j];
+      if( c==0 ) return -1;
+      if( c=='\\' ){
+        c = pParse->zJson[++j];
+        if( c=='"' || c=='\\' || c=='/' || c=='b' || c=='f'
+           || c=='n' || c=='r' || c=='t'
+           || (c=='u' && jsonIs4Hex(pParse->zJson+j+1)) ){
+          jnFlags = JNODE_ESCAPE;
+        }else{
+          return -1;
+        }
+      }else if( c=='"' ){
+        break;
+      }
+      j++;
+    }
+    jsonParseAddNode(pParse, JSON_STRING, j+1-i, &pParse->zJson[i]);
+    if( !pParse->oom ) pParse->aNode[pParse->nNode-1].jnFlags = jnFlags;
+    return j+1;
+  }else if( c=='n'
+         && strncmp(pParse->zJson+i,"null",4)==0
+         && !safe_isalnum(pParse->zJson[i+4]) ){
+    jsonParseAddNode(pParse, JSON_NULL, 0, 0);
+    return i+4;
+  }else if( c=='t'
+         && strncmp(pParse->zJson+i,"true",4)==0
+         && !safe_isalnum(pParse->zJson[i+4]) ){
+    jsonParseAddNode(pParse, JSON_TRUE, 0, 0);
+    return i+4;
+  }else if( c=='f'
+         && strncmp(pParse->zJson+i,"false",5)==0
+         && !safe_isalnum(pParse->zJson[i+5]) ){
+    jsonParseAddNode(pParse, JSON_FALSE, 0, 0);
+    return i+5;
+  }else if( c=='-' || (c>='0' && c<='9') ){
+    /* Parse number */
+    u8 seenDP = 0;
+    u8 seenE = 0;
+    j = i+1;
+    for(;; j++){
+      c = pParse->zJson[j];
+      if( c>='0' && c<='9' ) continue;
+      if( c=='.' ){
+        if( pParse->zJson[j-1]=='-' ) return -1;
+        if( seenDP ) return -1;
+        seenDP = 1;
+        continue;
+      }
+      if( c=='e' || c=='E' ){
+        if( pParse->zJson[j-1]<'0' ) return -1;
+        if( seenE ) return -1;
+        seenDP = seenE = 1;
+        c = pParse->zJson[j+1];
+        if( c=='+' || c=='-' ){
+          j++;
+          c = pParse->zJson[j+1];
+        }
+        if( c<'0' || c>'9' ) return -1;
+        continue;
+      }
+      break;
+    }
+    if( pParse->zJson[j-1]<'0' ) return -1;
+    jsonParseAddNode(pParse, seenDP ? JSON_REAL : JSON_INT,
+                        j - i, &pParse->zJson[i]);
+    return j;
+  }else if( c=='}' ){
+    return -2;  /* End of {...} */
+  }else if( c==']' ){
+    return -3;  /* End of [...] */
+  }else if( c==0 ){
+    return 0;   /* End of file */
+  }else{
+    return -1;  /* Syntax error */
+  }
+}
+
+/*
+** Parse a complete JSON string.  Return 0 on success or non-zero if there
+** are any errors.  If an error occurs, free all memory associated with
+** pParse.
+**
+** pParse is uninitialized when this routine is called.
+*/
+static int jsonParse(
+  JsonParse *pParse,           /* Initialize and fill this JsonParse object */
+  sqlite3_context *pCtx,       /* Report errors here */
+  const char *zJson            /* Input JSON text to be parsed */
+){
+  int i;
+  memset(pParse, 0, sizeof(*pParse));
+  if( zJson==0 ) return 1;
+  pParse->zJson = zJson;
+  i = jsonParseValue(pParse, 0);
+  if( pParse->oom ) i = -1;
+  if( i>0 ){
+    while( safe_isspace(zJson[i]) ) i++;
+    if( zJson[i] ) i = -1;
+  }
+  if( i<=0 ){
+    if( pCtx!=0 ){
+      if( pParse->oom ){
+        sqlite3_result_error_nomem(pCtx);
+      }else{
+        sqlite3_result_error(pCtx, "malformed JSON", -1);
+      }
+    }
+    jsonParseReset(pParse);
+    return 1;
+  }
+  return 0;
+}
+
+/* Mark node i of pParse as being a child of iParent.  Call recursively
+** to fill in all the descendants of node i.
+*/
+static void jsonParseFillInParentage(JsonParse *pParse, u32 i, u32 iParent){
+  JsonNode *pNode = &pParse->aNode[i];
+  u32 j;
+  pParse->aUp[i] = iParent;
+  switch( pNode->eType ){
+    case JSON_ARRAY: {
+      for(j=1; j<=pNode->n; j += jsonNodeSize(pNode+j)){
+        jsonParseFillInParentage(pParse, i+j, i);
+      }
+      break;
+    }
+    case JSON_OBJECT: {
+      for(j=1; j<=pNode->n; j += jsonNodeSize(pNode+j+1)+1){
+        pParse->aUp[i+j] = i;
+        jsonParseFillInParentage(pParse, i+j+1, i);
+      }
+      break;
+    }
+    default: {
+      break;
+    }
+  }
+}
+
+/*
+** Compute the parentage of all nodes in a completed parse.
+*/
+static int jsonParseFindParents(JsonParse *pParse){
+  u32 *aUp;
+  assert( pParse->aUp==0 );
+  aUp = pParse->aUp = sqlite3_malloc( sizeof(u32)*pParse->nNode );
+  if( aUp==0 ){
+    pParse->oom = 1;
+    return SQLITE_NOMEM;
+  }
+  jsonParseFillInParentage(pParse, 0, 0);
+  return SQLITE_OK;
+}
+
+/*
+** Compare the OBJECT label at pNode against zKey,nKey.  Return true on
+** a match.
+*/
+static int jsonLabelCompare(JsonNode *pNode, const char *zKey, u32 nKey){
+  if( pNode->jnFlags & JNODE_RAW ){
+    if( pNode->n!=nKey ) return 0;
+    return strncmp(pNode->u.zJContent, zKey, nKey)==0;
+  }else{
+    if( pNode->n!=nKey+2 ) return 0;
+    return strncmp(pNode->u.zJContent+1, zKey, nKey)==0;
+  }
+}
+
+/* forward declaration */
+static JsonNode *jsonLookupAppend(JsonParse*,const char*,int*,const char**);
+
+/*
+** Search along zPath to find the node specified.  Return a pointer
+** to that node, or NULL if zPath is malformed or if there is no such
+** node.
+**
+** If pApnd!=0, then try to append new nodes to complete zPath if it is
+** possible to do so and if no existing node corresponds to zPath.  If
+** new nodes are appended *pApnd is set to 1.
+*/
+static JsonNode *jsonLookupStep(
+  JsonParse *pParse,      /* The JSON to search */
+  u32 iRoot,              /* Begin the search at this node */
+  const char *zPath,      /* The path to search */
+  int *pApnd,             /* Append nodes to complete path if not NULL */
+  const char **pzErr      /* Make *pzErr point to any syntax error in zPath */
+){
+  u32 i, j, nKey;
+  const char *zKey;
+  JsonNode *pRoot = &pParse->aNode[iRoot];
+  if( zPath[0]==0 ) return pRoot;
+  if( zPath[0]=='.' ){
+    if( pRoot->eType!=JSON_OBJECT ) return 0;
+    zPath++;
+    if( zPath[0]=='"' ){
+      zKey = zPath + 1;
+      for(i=1; zPath[i] && zPath[i]!='"'; i++){}
+      nKey = i-1;
+      if( zPath[i] ){
+        i++;
+      }else{
+        *pzErr = zPath;
+        return 0;
+      }
+    }else{
+      zKey = zPath;
+      for(i=0; zPath[i] && zPath[i]!='.' && zPath[i]!='['; i++){}
+      nKey = i;
+    }
+    if( nKey==0 ){
+      *pzErr = zPath;
+      return 0;
+    }
+    j = 1;
+    for(;;){
+      while( j<=pRoot->n ){
+        if( jsonLabelCompare(pRoot+j, zKey, nKey) ){
+          return jsonLookupStep(pParse, iRoot+j+1, &zPath[i], pApnd, pzErr);
+        }
+        j++;
+        j += jsonNodeSize(&pRoot[j]);
+      }
+      if( (pRoot->jnFlags & JNODE_APPEND)==0 ) break;
+      iRoot += pRoot->u.iAppend;
+      pRoot = &pParse->aNode[iRoot];
+      j = 1;
+    }
+    if( pApnd ){
+      u32 iStart, iLabel;
+      JsonNode *pNode;
+      iStart = jsonParseAddNode(pParse, JSON_OBJECT, 2, 0);
+      iLabel = jsonParseAddNode(pParse, JSON_STRING, i, zPath);
+      zPath += i;
+      pNode = jsonLookupAppend(pParse, zPath, pApnd, pzErr);
+      if( pParse->oom ) return 0;
+      if( pNode ){
+        pRoot = &pParse->aNode[iRoot];
+        pRoot->u.iAppend = iStart - iRoot;
+        pRoot->jnFlags |= JNODE_APPEND;
+        pParse->aNode[iLabel].jnFlags |= JNODE_RAW;
+      }
+      return pNode;
+    }
+  }else if( zPath[0]=='[' && safe_isdigit(zPath[1]) ){
+    if( pRoot->eType!=JSON_ARRAY ) return 0;
+    i = 0;
+    j = 1;
+    while( safe_isdigit(zPath[j]) ){
+      i = i*10 + zPath[j] - '0';
+      j++;
+    }
+    if( zPath[j]!=']' ){
+      *pzErr = zPath;
+      return 0;
+    }
+    zPath += j + 1;
+    j = 1;
+    for(;;){
+      while( j<=pRoot->n && (i>0 || (pRoot[j].jnFlags & JNODE_REMOVE)!=0) ){
+        if( (pRoot[j].jnFlags & JNODE_REMOVE)==0 ) i--;
+        j += jsonNodeSize(&pRoot[j]);
+      }
+      if( (pRoot->jnFlags & JNODE_APPEND)==0 ) break;
+      iRoot += pRoot->u.iAppend;
+      pRoot = &pParse->aNode[iRoot];
+      j = 1;
+    }
+    if( j<=pRoot->n ){
+      return jsonLookupStep(pParse, iRoot+j, zPath, pApnd, pzErr);
+    }
+    if( i==0 && pApnd ){
+      u32 iStart;
+      JsonNode *pNode;
+      iStart = jsonParseAddNode(pParse, JSON_ARRAY, 1, 0);
+      pNode = jsonLookupAppend(pParse, zPath, pApnd, pzErr);
+      if( pParse->oom ) return 0;
+      if( pNode ){
+        pRoot = &pParse->aNode[iRoot];
+        pRoot->u.iAppend = iStart - iRoot;
+        pRoot->jnFlags |= JNODE_APPEND;
+      }
+      return pNode;
+    }
+  }else{
+    *pzErr = zPath;
+  }
+  return 0;
+}
+
+/*
+** Append content to pParse that will complete zPath.  Return a pointer
+** to the inserted node, or return NULL if the append fails.
+*/
+static JsonNode *jsonLookupAppend(
+  JsonParse *pParse,     /* Append content to the JSON parse */
+  const char *zPath,     /* Description of content to append */
+  int *pApnd,            /* Set this flag to 1 */
+  const char **pzErr     /* Make this point to any syntax error */
+){
+  *pApnd = 1;
+  if( zPath[0]==0 ){
+    jsonParseAddNode(pParse, JSON_NULL, 0, 0);
+    return pParse->oom ? 0 : &pParse->aNode[pParse->nNode-1];
+  }
+  if( zPath[0]=='.' ){
+    jsonParseAddNode(pParse, JSON_OBJECT, 0, 0);
+  }else if( strncmp(zPath,"[0]",3)==0 ){
+    jsonParseAddNode(pParse, JSON_ARRAY, 0, 0);
+  }else{
+    return 0;
+  }
+  if( pParse->oom ) return 0;
+  return jsonLookupStep(pParse, pParse->nNode-1, zPath, pApnd, pzErr);
+}
+
+/*
+** Return the text of a syntax error message on a JSON path.  Space is
+** obtained from sqlite3_malloc().
+*/
+static char *jsonPathSyntaxError(const char *zErr){
+  return sqlite3_mprintf("JSON path error near '%q'", zErr);
+}
+
+/*
+** Do a node lookup using zPath.  Return a pointer to the node on success.
+** Return NULL if not found or if there is an error.
+**
+** On an error, write an error message into pCtx and increment the
+** pParse->nErr counter.
+**
+** If pApnd!=NULL then try to append missing nodes and set *pApnd = 1 if
+** nodes are appended.
+*/
+static JsonNode *jsonLookup(
+  JsonParse *pParse,      /* The JSON to search */
+  const char *zPath,      /* The path to search */
+  int *pApnd,             /* Append nodes to complete path if not NULL */
+  sqlite3_context *pCtx   /* Report errors here, if not NULL */
+){
+  const char *zErr = 0;
+  JsonNode *pNode = 0;
+  char *zMsg;
+
+  if( zPath==0 ) return 0;
+  if( zPath[0]!='$' ){
+    zErr = zPath;
+    goto lookup_err;
+  }
+  zPath++;
+  pNode = jsonLookupStep(pParse, 0, zPath, pApnd, &zErr);
+  if( zErr==0 ) return pNode;
+
+lookup_err:
+  pParse->nErr++;
+  assert( zErr!=0 && pCtx!=0 );
+  zMsg = jsonPathSyntaxError(zErr);
+  if( zMsg ){
+    sqlite3_result_error(pCtx, zMsg, -1);
+    sqlite3_free(zMsg);
+  }else{
+    sqlite3_result_error_nomem(pCtx);
+  }
+  return 0;
+}
+
+
+/*
+** Report the wrong number of arguments for json_insert(), json_replace()
+** or json_set().
+*/
+static void jsonWrongNumArgs(
+  sqlite3_context *pCtx,
+  const char *zFuncName
+){
+  char *zMsg = sqlite3_mprintf("json_%s() needs an odd number of arguments",
+                               zFuncName);
+  sqlite3_result_error(pCtx, zMsg, -1);
+  sqlite3_free(zMsg);     
+}
+
+
+/****************************************************************************
+** SQL functions used for testing and debugging
+****************************************************************************/
+
+#ifdef SQLITE_DEBUG
+/*
+** The json_parse(JSON) function returns a string which describes
+** a parse of the JSON provided.  Or it returns NULL if JSON is not
+** well-formed.
+*/
+static void jsonParseFunc(
+  sqlite3_context *ctx,
+  int argc,
+  sqlite3_value **argv
+){
+  JsonString s;       /* Output string - not real JSON */
+  JsonParse x;        /* The parse */
+  u32 i;
+
+  assert( argc==1 );
+  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
+  jsonParseFindParents(&x);
+  jsonInit(&s, ctx);
+  for(i=0; i<x.nNode; i++){
+    const char *zType;
+    if( x.aNode[i].jnFlags & JNODE_LABEL ){
+      assert( x.aNode[i].eType==JSON_STRING );
+      zType = "label";
+    }else{
+      zType = jsonType[x.aNode[i].eType];
+    }
+    jsonPrintf(100, &s,"node %3u: %7s n=%-4d up=%-4d",
+               i, zType, x.aNode[i].n, x.aUp[i]);
+    if( x.aNode[i].u.zJContent!=0 ){
+      jsonAppendRaw(&s, " ", 1);
+      jsonAppendRaw(&s, x.aNode[i].u.zJContent, x.aNode[i].n);
+    }
+    jsonAppendRaw(&s, "\n", 1);
+  }
+  jsonParseReset(&x);
+  jsonResult(&s);
+}
+
+/*
+** The json_test1(JSON) function return true (1) if the input is JSON
+** text generated by another json function.  It returns (0) if the input
+** is not known to be JSON.
+*/
+static void jsonTest1Func(
+  sqlite3_context *ctx,
+  int argc,
+  sqlite3_value **argv
+){
+  UNUSED_PARAM(argc);
+  sqlite3_result_int(ctx, sqlite3_value_subtype(argv[0])==JSON_SUBTYPE);
+}
+#endif /* SQLITE_DEBUG */
+
+/****************************************************************************
+** Scalar SQL function implementations
+****************************************************************************/
+
+/*
+** Implementation of the json_QUOTE(VALUE) function.  Return a JSON value
+** corresponding to the SQL value input.  Mostly this means putting 
+** double-quotes around strings and returning the unquoted string "null"
+** when given a NULL input.
+*/
+static void jsonQuoteFunc(
+  sqlite3_context *ctx,
+  int argc,
+  sqlite3_value **argv
+){
+  JsonString jx;
+  UNUSED_PARAM(argc);
+
+  jsonInit(&jx, ctx);
+  jsonAppendValue(&jx, argv[0]);
+  jsonResult(&jx);
+  sqlite3_result_subtype(ctx, JSON_SUBTYPE);
+}
+
+/*
+** Implementation of the json_array(VALUE,...) function.  Return a JSON
+** array that contains all values given in arguments.  Or if any argument
+** is a BLOB, throw an error.
+*/
+static void jsonArrayFunc(
+  sqlite3_context *ctx,
+  int argc,
+  sqlite3_value **argv
+){
+  int i;
+  JsonString jx;
+
+  jsonInit(&jx, ctx);
+  jsonAppendChar(&jx, '[');
+  for(i=0; i<argc; i++){
+    jsonAppendSeparator(&jx);
+    jsonAppendValue(&jx, argv[i]);
+  }
+  jsonAppendChar(&jx, ']');
+  jsonResult(&jx);
+  sqlite3_result_subtype(ctx, JSON_SUBTYPE);
+}
+
+
+/*
+** json_array_length(JSON)
+** json_array_length(JSON, PATH)
+**
+** Return the number of elements in the top-level JSON array.  
+** Return 0 if the input is not a well-formed JSON array.
+*/
+static void jsonArrayLengthFunc(
+  sqlite3_context *ctx,
+  int argc,
+  sqlite3_value **argv
+){
+  JsonParse x;          /* The parse */
+  sqlite3_int64 n = 0;
+  u32 i;
+  JsonNode *pNode;
+
+  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
+  assert( x.nNode );
+  if( argc==2 ){
+    const char *zPath = (const char*)sqlite3_value_text(argv[1]);
+    pNode = jsonLookup(&x, zPath, 0, ctx);
+  }else{
+    pNode = x.aNode;
+  }
+  if( pNode==0 ){
+    x.nErr = 1;
+  }else if( pNode->eType==JSON_ARRAY ){
+    assert( (pNode->jnFlags & JNODE_APPEND)==0 );
+    for(i=1; i<=pNode->n; n++){
+      i += jsonNodeSize(&pNode[i]);
+    }
+  }
+  if( x.nErr==0 ) sqlite3_result_int64(ctx, n);
+  jsonParseReset(&x);
+}
+
+/*
+** json_extract(JSON, PATH, ...)
+**
+** Return the element described by PATH.  Return NULL if there is no
+** PATH element.  If there are multiple PATHs, then return a JSON array
+** with the result from each path.  Throw an error if the JSON or any PATH
+** is malformed.
+*/
+static void jsonExtractFunc(
+  sqlite3_context *ctx,
+  int argc,
+  sqlite3_value **argv
+){
+  JsonParse x;          /* The parse */
+  JsonNode *pNode;
+  const char *zPath;
+  JsonString jx;
+  int i;
+
+  if( argc<2 ) return;
+  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
+  jsonInit(&jx, ctx);
+  jsonAppendChar(&jx, '[');
+  for(i=1; i<argc; i++){
+    zPath = (const char*)sqlite3_value_text(argv[i]);
+    pNode = jsonLookup(&x, zPath, 0, ctx);
+    if( x.nErr ) break;
+    if( argc>2 ){
+      jsonAppendSeparator(&jx);
+      if( pNode ){
+        jsonRenderNode(pNode, &jx, 0);
+      }else{
+        jsonAppendRaw(&jx, "null", 4);
+      }
+    }else if( pNode ){
+      jsonReturn(pNode, ctx, 0);
+    }
+  }
+  if( argc>2 && i==argc ){
+    jsonAppendChar(&jx, ']');
+    jsonResult(&jx);
+    sqlite3_result_subtype(ctx, JSON_SUBTYPE);
+  }
+  jsonReset(&jx);
+  jsonParseReset(&x);
+}
+
+/*
+** Implementation of the json_object(NAME,VALUE,...) function.  Return a JSON
+** object that contains all name/value given in arguments.  Or if any name
+** is not a string or if any value is a BLOB, throw an error.
+*/
+static void jsonObjectFunc(
+  sqlite3_context *ctx,
+  int argc,
+  sqlite3_value **argv
+){
+  int i;
+  JsonString jx;
+  const char *z;
+  u32 n;
+
+  if( argc&1 ){
+    sqlite3_result_error(ctx, "json_object() requires an even number "
+                                  "of arguments", -1);
+    return;
+  }
+  jsonInit(&jx, ctx);
+  jsonAppendChar(&jx, '{');
+  for(i=0; i<argc; i+=2){
+    if( sqlite3_value_type(argv[i])!=SQLITE_TEXT ){
+      sqlite3_result_error(ctx, "json_object() labels must be TEXT", -1);
+      jsonReset(&jx);
+      return;
+    }
+    jsonAppendSeparator(&jx);
+    z = (const char*)sqlite3_value_text(argv[i]);
+    n = (u32)sqlite3_value_bytes(argv[i]);
+    jsonAppendString(&jx, z, n);
+    jsonAppendChar(&jx, ':');
+    jsonAppendValue(&jx, argv[i+1]);
+  }
+  jsonAppendChar(&jx, '}');
+  jsonResult(&jx);
+  sqlite3_result_subtype(ctx, JSON_SUBTYPE);
+}
+
+
+/*
+** json_remove(JSON, PATH, ...)
+**
+** Remove the named elements from JSON and return the result.  malformed
+** JSON or PATH arguments result in an error.
+*/
+static void jsonRemoveFunc(
+  sqlite3_context *ctx,
+  int argc,
+  sqlite3_value **argv
+){
+  JsonParse x;          /* The parse */
+  JsonNode *pNode;
+  const char *zPath;
+  u32 i;
+
+  if( argc<1 ) return;
+  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
+  assert( x.nNode );
+  for(i=1; i<(u32)argc; i++){
+    zPath = (const char*)sqlite3_value_text(argv[i]);
+    if( zPath==0 ) goto remove_done;
+    pNode = jsonLookup(&x, zPath, 0, ctx);
+    if( x.nErr ) goto remove_done;
+    if( pNode ) pNode->jnFlags |= JNODE_REMOVE;
+  }
+  if( (x.aNode[0].jnFlags & JNODE_REMOVE)==0 ){
+    jsonReturnJson(x.aNode, ctx, 0);
+  }
+remove_done:
+  jsonParseReset(&x);
+}
+
+/*
+** json_replace(JSON, PATH, VALUE, ...)
+**
+** Replace the value at PATH with VALUE.  If PATH does not already exist,
+** this routine is a no-op.  If JSON or PATH is malformed, throw an error.
+*/
+static void jsonReplaceFunc(
+  sqlite3_context *ctx,
+  int argc,
+  sqlite3_value **argv
+){
+  JsonParse x;          /* The parse */
+  JsonNode *pNode;
+  const char *zPath;
+  u32 i;
+
+  if( argc<1 ) return;
+  if( (argc&1)==0 ) {
+    jsonWrongNumArgs(ctx, "replace");
+    return;
+  }
+  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
+  assert( x.nNode );
+  for(i=1; i<(u32)argc; i+=2){
+    zPath = (const char*)sqlite3_value_text(argv[i]);
+    pNode = jsonLookup(&x, zPath, 0, ctx);
+    if( x.nErr ) goto replace_err;
+    if( pNode ){
+      pNode->jnFlags |= (u8)JNODE_REPLACE;
+      pNode->iVal = (u8)(i+1);
+    }
+  }
+  if( x.aNode[0].jnFlags & JNODE_REPLACE ){
+    sqlite3_result_value(ctx, argv[x.aNode[0].iVal]);
+  }else{
+    jsonReturnJson(x.aNode, ctx, argv);
+  }
+replace_err:
+  jsonParseReset(&x);
+}
+
+/*
+** json_set(JSON, PATH, VALUE, ...)
+**
+** Set the value at PATH to VALUE.  Create the PATH if it does not already
+** exist.  Overwrite existing values that do exist.
+** If JSON or PATH is malformed, throw an error.
+**
+** json_insert(JSON, PATH, VALUE, ...)
+**
+** Create PATH and initialize it to VALUE.  If PATH already exists, this
+** routine is a no-op.  If JSON or PATH is malformed, throw an error.
+*/
+static void jsonSetFunc(
+  sqlite3_context *ctx,
+  int argc,
+  sqlite3_value **argv
+){
+  JsonParse x;          /* The parse */
+  JsonNode *pNode;
+  const char *zPath;
+  u32 i;
+  int bApnd;
+  int bIsSet = *(int*)sqlite3_user_data(ctx);
+
+  if( argc<1 ) return;
+  if( (argc&1)==0 ) {
+    jsonWrongNumArgs(ctx, bIsSet ? "set" : "insert");
+    return;
+  }
+  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
+  assert( x.nNode );
+  for(i=1; i<(u32)argc; i+=2){
+    zPath = (const char*)sqlite3_value_text(argv[i]);
+    bApnd = 0;
+    pNode = jsonLookup(&x, zPath, &bApnd, ctx);
+    if( x.oom ){
+      sqlite3_result_error_nomem(ctx);
+      goto jsonSetDone;
+    }else if( x.nErr ){
+      goto jsonSetDone;
+    }else if( pNode && (bApnd || bIsSet) ){
+      pNode->jnFlags |= (u8)JNODE_REPLACE;
+      pNode->iVal = (u8)(i+1);
+    }
+  }
+  if( x.aNode[0].jnFlags & JNODE_REPLACE ){
+    sqlite3_result_value(ctx, argv[x.aNode[0].iVal]);
+  }else{
+    jsonReturnJson(x.aNode, ctx, argv);
+  }
+jsonSetDone:
+  jsonParseReset(&x);
+}
+
+/*
+** json_type(JSON)
+** json_type(JSON, PATH)
+**
+** Return the top-level "type" of a JSON string.  Throw an error if
+** either the JSON or PATH inputs are not well-formed.
+*/
+static void jsonTypeFunc(
+  sqlite3_context *ctx,
+  int argc,
+  sqlite3_value **argv
+){
+  JsonParse x;          /* The parse */
+  const char *zPath;
+  JsonNode *pNode;
+
+  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
+  assert( x.nNode );
+  if( argc==2 ){
+    zPath = (const char*)sqlite3_value_text(argv[1]);
+    pNode = jsonLookup(&x, zPath, 0, ctx);
+  }else{
+    pNode = x.aNode;
+  }
+  if( pNode ){
+    sqlite3_result_text(ctx, jsonType[pNode->eType], -1, SQLITE_STATIC);
+  }
+  jsonParseReset(&x);
+}
+
+/*
+** json_valid(JSON)
+**
+** Return 1 if JSON is a well-formed JSON string according to RFC-7159.
+** Return 0 otherwise.
+*/
+static void jsonValidFunc(
+  sqlite3_context *ctx,
+  int argc,
+  sqlite3_value **argv
+){
+  JsonParse x;          /* The parse */
+  int rc = 0;
+
+  UNUSED_PARAM(argc);
+  if( jsonParse(&x, 0, (const char*)sqlite3_value_text(argv[0]))==0 ){
+    rc = 1;
+  }
+  jsonParseReset(&x);
+  sqlite3_result_int(ctx, rc);
+}
+
+
+/****************************************************************************
+** Aggregate SQL function implementations
+****************************************************************************/
+/*
+** json_group_array(VALUE)
+**
+** Return a JSON array composed of all values in the aggregate.
+*/
+static void jsonArrayStep(
+  sqlite3_context *ctx,
+  int argc,
+  sqlite3_value **argv
+){
+  JsonString *pStr;
+  UNUSED_PARAM(argc);
+  pStr = (JsonString*)sqlite3_aggregate_context(ctx, sizeof(*pStr));
+  if( pStr ){
+    if( pStr->zBuf==0 ){
+      jsonInit(pStr, ctx);
+      jsonAppendChar(pStr, '[');
+    }else{
+      jsonAppendChar(pStr, ',');
+      pStr->pCtx = ctx;
+    }
+    jsonAppendValue(pStr, argv[0]);
+  }
+}
+static void jsonArrayFinal(sqlite3_context *ctx){
+  JsonString *pStr;
+  pStr = (JsonString*)sqlite3_aggregate_context(ctx, 0);
+  if( pStr ){
+    pStr->pCtx = ctx;
+    jsonAppendChar(pStr, ']');
+    if( pStr->bErr ){
+      if( pStr->bErr==1 ) sqlite3_result_error_nomem(ctx);
+      assert( pStr->bStatic );
+    }else{
+      sqlite3_result_text(ctx, pStr->zBuf, pStr->nUsed,
+                          pStr->bStatic ? SQLITE_TRANSIENT : sqlite3_free);
+      pStr->bStatic = 1;
+    }
+  }else{
+    sqlite3_result_text(ctx, "[]", 2, SQLITE_STATIC);
+  }
+  sqlite3_result_subtype(ctx, JSON_SUBTYPE);
+}
+
+/*
+** json_group_obj(NAME,VALUE)
+**
+** Return a JSON object composed of all names and values in the aggregate.
+*/
+static void jsonObjectStep(
+  sqlite3_context *ctx,
+  int argc,
+  sqlite3_value **argv
+){
+  JsonString *pStr;
+  const char *z;
+  u32 n;
+  UNUSED_PARAM(argc);
+  pStr = (JsonString*)sqlite3_aggregate_context(ctx, sizeof(*pStr));
+  if( pStr ){
+    if( pStr->zBuf==0 ){
+      jsonInit(pStr, ctx);
+      jsonAppendChar(pStr, '{');
+    }else{
+      jsonAppendChar(pStr, ',');
+      pStr->pCtx = ctx;
+    }
+    z = (const char*)sqlite3_value_text(argv[0]);
+    n = (u32)sqlite3_value_bytes(argv[0]);
+    jsonAppendString(pStr, z, n);
+    jsonAppendChar(pStr, ':');
+    jsonAppendValue(pStr, argv[1]);
+  }
+}
+static void jsonObjectFinal(sqlite3_context *ctx){
+  JsonString *pStr;
+  pStr = (JsonString*)sqlite3_aggregate_context(ctx, 0);
+  if( pStr ){
+    jsonAppendChar(pStr, '}');
+    if( pStr->bErr ){
+      if( pStr->bErr==1 ) sqlite3_result_error_nomem(ctx);
+      assert( pStr->bStatic );
+    }else{
+      sqlite3_result_text(ctx, pStr->zBuf, pStr->nUsed,
+                          pStr->bStatic ? SQLITE_TRANSIENT : sqlite3_free);
+      pStr->bStatic = 1;
+    }
+  }else{
+    sqlite3_result_text(ctx, "{}", 2, SQLITE_STATIC);
+  }
+  sqlite3_result_subtype(ctx, JSON_SUBTYPE);
+}
+
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/****************************************************************************
+** The json_each virtual table
+****************************************************************************/
+typedef struct JsonEachCursor JsonEachCursor;
+struct JsonEachCursor {
+  sqlite3_vtab_cursor base;  /* Base class - must be first */
+  u32 iRowid;                /* The rowid */
+  u32 iBegin;                /* The first node of the scan */
+  u32 i;                     /* Index in sParse.aNode[] of current row */
+  u32 iEnd;                  /* EOF when i equals or exceeds this value */
+  u8 eType;                  /* Type of top-level element */
+  u8 bRecursive;             /* True for json_tree().  False for json_each() */
+  char *zJson;               /* Input JSON */
+  char *zRoot;               /* Path by which to filter zJson */
+  JsonParse sParse;          /* Parse of the input JSON */
+};
+
+/* Constructor for the json_each virtual table */
+static int jsonEachConnect(
+  sqlite3 *db,
+  void *pAux,
+  int argc, const char *const*argv,
+  sqlite3_vtab **ppVtab,
+  char **pzErr
+){
+  sqlite3_vtab *pNew;
+  int rc;
+
+/* Column numbers */
+#define JEACH_KEY     0
+#define JEACH_VALUE   1
+#define JEACH_TYPE    2
+#define JEACH_ATOM    3
+#define JEACH_ID      4
+#define JEACH_PARENT  5
+#define JEACH_FULLKEY 6
+#define JEACH_PATH    7
+#define JEACH_JSON    8
+#define JEACH_ROOT    9
+
+  UNUSED_PARAM(pzErr);
+  UNUSED_PARAM(argv);
+  UNUSED_PARAM(argc);
+  UNUSED_PARAM(pAux);
+  rc = sqlite3_declare_vtab(db, 
+     "CREATE TABLE x(key,value,type,atom,id,parent,fullkey,path,"
+                    "json HIDDEN,root HIDDEN)");
+  if( rc==SQLITE_OK ){
+    pNew = *ppVtab = sqlite3_malloc( sizeof(*pNew) );
+    if( pNew==0 ) return SQLITE_NOMEM;
+    memset(pNew, 0, sizeof(*pNew));
+  }
+  return rc;
+}
+
+/* destructor for json_each virtual table */
+static int jsonEachDisconnect(sqlite3_vtab *pVtab){
+  sqlite3_free(pVtab);
+  return SQLITE_OK;
+}
+
+/* constructor for a JsonEachCursor object for json_each(). */
+static int jsonEachOpenEach(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
+  JsonEachCursor *pCur;
+
+  UNUSED_PARAM(p);
+  pCur = sqlite3_malloc( sizeof(*pCur) );
+  if( pCur==0 ) return SQLITE_NOMEM;
+  memset(pCur, 0, sizeof(*pCur));
+  *ppCursor = &pCur->base;
+  return SQLITE_OK;
+}
+
+/* constructor for a JsonEachCursor object for json_tree(). */
+static int jsonEachOpenTree(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
+  int rc = jsonEachOpenEach(p, ppCursor);
+  if( rc==SQLITE_OK ){
+    JsonEachCursor *pCur = (JsonEachCursor*)*ppCursor;
+    pCur->bRecursive = 1;
+  }
+  return rc;
+}
+
+/* Reset a JsonEachCursor back to its original state.  Free any memory
+** held. */
+static void jsonEachCursorReset(JsonEachCursor *p){
+  sqlite3_free(p->zJson);
+  sqlite3_free(p->zRoot);
+  jsonParseReset(&p->sParse);
+  p->iRowid = 0;
+  p->i = 0;
+  p->iEnd = 0;
+  p->eType = 0;
+  p->zJson = 0;
+  p->zRoot = 0;
+}
+
+/* Destructor for a jsonEachCursor object */
+static int jsonEachClose(sqlite3_vtab_cursor *cur){
+  JsonEachCursor *p = (JsonEachCursor*)cur;
+  jsonEachCursorReset(p);
+  sqlite3_free(cur);
+  return SQLITE_OK;
+}
+
+/* Return TRUE if the jsonEachCursor object has been advanced off the end
+** of the JSON object */
+static int jsonEachEof(sqlite3_vtab_cursor *cur){
+  JsonEachCursor *p = (JsonEachCursor*)cur;
+  return p->i >= p->iEnd;
+}
+
+/* Advance the cursor to the next element for json_tree() */
+static int jsonEachNext(sqlite3_vtab_cursor *cur){
+  JsonEachCursor *p = (JsonEachCursor*)cur;
+  if( p->bRecursive ){
+    if( p->sParse.aNode[p->i].jnFlags & JNODE_LABEL ) p->i++;
+    p->i++;
+    p->iRowid++;
+    if( p->i<p->iEnd ){
+      u32 iUp = p->sParse.aUp[p->i];
+      JsonNode *pUp = &p->sParse.aNode[iUp];
+      p->eType = pUp->eType;
+      if( pUp->eType==JSON_ARRAY ){
+        if( iUp==p->i-1 ){
+          pUp->u.iKey = 0;
+        }else{
+          pUp->u.iKey++;
+        }
+      }
+    }
+  }else{
+    switch( p->eType ){
+      case JSON_ARRAY: {
+        p->i += jsonNodeSize(&p->sParse.aNode[p->i]);
+        p->iRowid++;
+        break;
+      }
+      case JSON_OBJECT: {
+        p->i += 1 + jsonNodeSize(&p->sParse.aNode[p->i+1]);
+        p->iRowid++;
+        break;
+      }
+      default: {
+        p->i = p->iEnd;
+        break;
+      }
+    }
+  }
+  return SQLITE_OK;
+}
+
+/* Append the name of the path for element i to pStr
+*/
+static void jsonEachComputePath(
+  JsonEachCursor *p,       /* The cursor */
+  JsonString *pStr,        /* Write the path here */
+  u32 i                    /* Path to this element */
+){
+  JsonNode *pNode, *pUp;
+  u32 iUp;
+  if( i==0 ){
+    jsonAppendChar(pStr, '$');
+    return;
+  }
+  iUp = p->sParse.aUp[i];
+  jsonEachComputePath(p, pStr, iUp);
+  pNode = &p->sParse.aNode[i];
+  pUp = &p->sParse.aNode[iUp];
+  if( pUp->eType==JSON_ARRAY ){
+    jsonPrintf(30, pStr, "[%d]", pUp->u.iKey);
+  }else{
+    assert( pUp->eType==JSON_OBJECT );
+    if( (pNode->jnFlags & JNODE_LABEL)==0 ) pNode--;
+    assert( pNode->eType==JSON_STRING );
+    assert( pNode->jnFlags & JNODE_LABEL );
+    jsonPrintf(pNode->n+1, pStr, ".%.*s", pNode->n-2, pNode->u.zJContent+1);
+  }
+}
+
+/* Return the value of a column */
+static int jsonEachColumn(
+  sqlite3_vtab_cursor *cur,   /* The cursor */
+  sqlite3_context *ctx,       /* First argument to sqlite3_result_...() */
+  int i                       /* Which column to return */
+){
+  JsonEachCursor *p = (JsonEachCursor*)cur;
+  JsonNode *pThis = &p->sParse.aNode[p->i];
+  switch( i ){
+    case JEACH_KEY: {
+      if( p->i==0 ) break;
+      if( p->eType==JSON_OBJECT ){
+        jsonReturn(pThis, ctx, 0);
+      }else if( p->eType==JSON_ARRAY ){
+        u32 iKey;
+        if( p->bRecursive ){
+          if( p->iRowid==0 ) break;
+          iKey = p->sParse.aNode[p->sParse.aUp[p->i]].u.iKey;
+        }else{
+          iKey = p->iRowid;
+        }
+        sqlite3_result_int64(ctx, (sqlite3_int64)iKey);
+      }
+      break;
+    }
+    case JEACH_VALUE: {
+      if( pThis->jnFlags & JNODE_LABEL ) pThis++;
+      jsonReturn(pThis, ctx, 0);
+      break;
+    }
+    case JEACH_TYPE: {
+      if( pThis->jnFlags & JNODE_LABEL ) pThis++;
+      sqlite3_result_text(ctx, jsonType[pThis->eType], -1, SQLITE_STATIC);
+      break;
+    }
+    case JEACH_ATOM: {
+      if( pThis->jnFlags & JNODE_LABEL ) pThis++;
+      if( pThis->eType>=JSON_ARRAY ) break;
+      jsonReturn(pThis, ctx, 0);
+      break;
+    }
+    case JEACH_ID: {
+      sqlite3_result_int64(ctx, 
+         (sqlite3_int64)p->i + ((pThis->jnFlags & JNODE_LABEL)!=0));
+      break;
+    }
+    case JEACH_PARENT: {
+      if( p->i>p->iBegin && p->bRecursive ){
+        sqlite3_result_int64(ctx, (sqlite3_int64)p->sParse.aUp[p->i]);
+      }
+      break;
+    }
+    case JEACH_FULLKEY: {
+      JsonString x;
+      jsonInit(&x, ctx);
+      if( p->bRecursive ){
+        jsonEachComputePath(p, &x, p->i);
+      }else{
+        if( p->zRoot ){
+          jsonAppendRaw(&x, p->zRoot, (int)strlen(p->zRoot));
+        }else{
+          jsonAppendChar(&x, '$');
+        }
+        if( p->eType==JSON_ARRAY ){
+          jsonPrintf(30, &x, "[%d]", p->iRowid);
+        }else{
+          jsonPrintf(pThis->n, &x, ".%.*s", pThis->n-2, pThis->u.zJContent+1);
+        }
+      }
+      jsonResult(&x);
+      break;
+    }
+    case JEACH_PATH: {
+      if( p->bRecursive ){
+        JsonString x;
+        jsonInit(&x, ctx);
+        jsonEachComputePath(p, &x, p->sParse.aUp[p->i]);
+        jsonResult(&x);
+        break;
+      }
+      /* For json_each() path and root are the same so fall through
+      ** into the root case */
+    }
+    default: {
+      const char *zRoot = p->zRoot;
+      if( zRoot==0 ) zRoot = "$";
+      sqlite3_result_text(ctx, zRoot, -1, SQLITE_STATIC);
+      break;
+    }
+    case JEACH_JSON: {
+      assert( i==JEACH_JSON );
+      sqlite3_result_text(ctx, p->sParse.zJson, -1, SQLITE_STATIC);
+      break;
+    }
+  }
+  return SQLITE_OK;
+}
+
+/* Return the current rowid value */
+static int jsonEachRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
+  JsonEachCursor *p = (JsonEachCursor*)cur;
+  *pRowid = p->iRowid;
+  return SQLITE_OK;
+}
+
+/* The query strategy is to look for an equality constraint on the json
+** column.  Without such a constraint, the table cannot operate.  idxNum is
+** 1 if the constraint is found, 3 if the constraint and zRoot are found,
+** and 0 otherwise.
+*/
+static int jsonEachBestIndex(
+  sqlite3_vtab *tab,
+  sqlite3_index_info *pIdxInfo
+){
+  int i;
+  int jsonIdx = -1;
+  int rootIdx = -1;
+  const struct sqlite3_index_constraint *pConstraint;
+
+  UNUSED_PARAM(tab);
+  pConstraint = pIdxInfo->aConstraint;
+  for(i=0; i<pIdxInfo->nConstraint; i++, pConstraint++){
+    if( pConstraint->usable==0 ) continue;
+    if( pConstraint->op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
+    switch( pConstraint->iColumn ){
+      case JEACH_JSON:   jsonIdx = i;    break;
+      case JEACH_ROOT:   rootIdx = i;    break;
+      default:           /* no-op */     break;
+    }
+  }
+  if( jsonIdx<0 ){
+    pIdxInfo->idxNum = 0;
+    pIdxInfo->estimatedCost = 1e99;
+  }else{
+    pIdxInfo->estimatedCost = 1.0;
+    pIdxInfo->aConstraintUsage[jsonIdx].argvIndex = 1;
+    pIdxInfo->aConstraintUsage[jsonIdx].omit = 1;
+    if( rootIdx<0 ){
+      pIdxInfo->idxNum = 1;
+    }else{
+      pIdxInfo->aConstraintUsage[rootIdx].argvIndex = 2;
+      pIdxInfo->aConstraintUsage[rootIdx].omit = 1;
+      pIdxInfo->idxNum = 3;
+    }
+  }
+  return SQLITE_OK;
+}
+
+/* Start a search on a new JSON string */
+static int jsonEachFilter(
+  sqlite3_vtab_cursor *cur,
+  int idxNum, const char *idxStr,
+  int argc, sqlite3_value **argv
+){
+  JsonEachCursor *p = (JsonEachCursor*)cur;
+  const char *z;
+  const char *zRoot = 0;
+  sqlite3_int64 n;
+
+  UNUSED_PARAM(idxStr);
+  UNUSED_PARAM(argc);
+  jsonEachCursorReset(p);
+  if( idxNum==0 ) return SQLITE_OK;
+  z = (const char*)sqlite3_value_text(argv[0]);
+  if( z==0 ) return SQLITE_OK;
+  n = sqlite3_value_bytes(argv[0]);
+  p->zJson = sqlite3_malloc64( n+1 );
+  if( p->zJson==0 ) return SQLITE_NOMEM;
+  memcpy(p->zJson, z, (size_t)n+1);
+  if( jsonParse(&p->sParse, 0, p->zJson) ){
+    int rc = SQLITE_NOMEM;
+    if( p->sParse.oom==0 ){
+      sqlite3_free(cur->pVtab->zErrMsg);
+      cur->pVtab->zErrMsg = sqlite3_mprintf("malformed JSON");
+      if( cur->pVtab->zErrMsg ) rc = SQLITE_ERROR;
+    }
+    jsonEachCursorReset(p);
+    return rc;
+  }else if( p->bRecursive && jsonParseFindParents(&p->sParse) ){
+    jsonEachCursorReset(p);
+    return SQLITE_NOMEM;
+  }else{
+    JsonNode *pNode = 0;
+    if( idxNum==3 ){
+      const char *zErr = 0;
+      zRoot = (const char*)sqlite3_value_text(argv[1]);
+      if( zRoot==0 ) return SQLITE_OK;
+      n = sqlite3_value_bytes(argv[1]);
+      p->zRoot = sqlite3_malloc64( n+1 );
+      if( p->zRoot==0 ) return SQLITE_NOMEM;
+      memcpy(p->zRoot, zRoot, (size_t)n+1);
+      if( zRoot[0]!='$' ){
+        zErr = zRoot;
+      }else{
+        pNode = jsonLookupStep(&p->sParse, 0, p->zRoot+1, 0, &zErr);
+      }
+      if( zErr ){
+        sqlite3_free(cur->pVtab->zErrMsg);
+        cur->pVtab->zErrMsg = jsonPathSyntaxError(zErr);
+        jsonEachCursorReset(p);
+        return cur->pVtab->zErrMsg ? SQLITE_ERROR : SQLITE_NOMEM;
+      }else if( pNode==0 ){
+        return SQLITE_OK;
+      }
+    }else{
+      pNode = p->sParse.aNode;
+    }
+    p->iBegin = p->i = (int)(pNode - p->sParse.aNode);
+    p->eType = pNode->eType;
+    if( p->eType>=JSON_ARRAY ){
+      pNode->u.iKey = 0;
+      p->iEnd = p->i + pNode->n + 1;
+      if( p->bRecursive ){
+        p->eType = p->sParse.aNode[p->sParse.aUp[p->i]].eType;
+        if( p->i>0 && (p->sParse.aNode[p->i-1].jnFlags & JNODE_LABEL)!=0 ){
+          p->i--;
+        }
+      }else{
+        p->i++;
+      }
+    }else{
+      p->iEnd = p->i+1;
+    }
+  }
+  return SQLITE_OK;
+}
+
+/* The methods of the json_each virtual table */
+static sqlite3_module jsonEachModule = {
+  0,                         /* iVersion */
+  0,                         /* xCreate */
+  jsonEachConnect,           /* xConnect */
+  jsonEachBestIndex,         /* xBestIndex */
+  jsonEachDisconnect,        /* xDisconnect */
+  0,                         /* xDestroy */
+  jsonEachOpenEach,          /* xOpen - open a cursor */
+  jsonEachClose,             /* xClose - close a cursor */
+  jsonEachFilter,            /* xFilter - configure scan constraints */
+  jsonEachNext,              /* xNext - advance a cursor */
+  jsonEachEof,               /* xEof - check for end of scan */
+  jsonEachColumn,            /* xColumn - read data */
+  jsonEachRowid,             /* xRowid - read data */
+  0,                         /* xUpdate */
+  0,                         /* xBegin */
+  0,                         /* xSync */
+  0,                         /* xCommit */
+  0,                         /* xRollback */
+  0,                         /* xFindMethod */
+  0,                         /* xRename */
+  0,                         /* xSavepoint */
+  0,                         /* xRelease */
+  0                          /* xRollbackTo */
+};
+
+/* The methods of the json_tree virtual table. */
+static sqlite3_module jsonTreeModule = {
+  0,                         /* iVersion */
+  0,                         /* xCreate */
+  jsonEachConnect,           /* xConnect */
+  jsonEachBestIndex,         /* xBestIndex */
+  jsonEachDisconnect,        /* xDisconnect */
+  0,                         /* xDestroy */
+  jsonEachOpenTree,          /* xOpen - open a cursor */
+  jsonEachClose,             /* xClose - close a cursor */
+  jsonEachFilter,            /* xFilter - configure scan constraints */
+  jsonEachNext,              /* xNext - advance a cursor */
+  jsonEachEof,               /* xEof - check for end of scan */
+  jsonEachColumn,            /* xColumn - read data */
+  jsonEachRowid,             /* xRowid - read data */
+  0,                         /* xUpdate */
+  0,                         /* xBegin */
+  0,                         /* xSync */
+  0,                         /* xCommit */
+  0,                         /* xRollback */
+  0,                         /* xFindMethod */
+  0,                         /* xRename */
+  0,                         /* xSavepoint */
+  0,                         /* xRelease */
+  0                          /* xRollbackTo */
+};
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+/****************************************************************************
+** The following routines are the only publically visible identifiers in this
+** file.  Call the following routines in order to register the various SQL
+** functions and the virtual table implemented by this file.
+****************************************************************************/
+
+SQLITE_PRIVATE int sqlite3Json1Init(sqlite3 *db){
+  int rc = SQLITE_OK;
+  unsigned int i;
+  static const struct {
+     const char *zName;
+     int nArg;
+     int flag;
+     void (*xFunc)(sqlite3_context*,int,sqlite3_value**);
+  } aFunc[] = {
+    { "json",                 1, 0,   jsonRemoveFunc        },
+    { "json_array",          -1, 0,   jsonArrayFunc         },
+    { "json_array_length",    1, 0,   jsonArrayLengthFunc   },
+    { "json_array_length",    2, 0,   jsonArrayLengthFunc   },
+    { "json_extract",        -1, 0,   jsonExtractFunc       },
+    { "json_insert",         -1, 0,   jsonSetFunc           },
+    { "json_object",         -1, 0,   jsonObjectFunc        },
+    { "json_quote",           1, 0,   jsonQuoteFunc         },
+    { "json_remove",         -1, 0,   jsonRemoveFunc        },
+    { "json_replace",        -1, 0,   jsonReplaceFunc       },
+    { "json_set",            -1, 1,   jsonSetFunc           },
+    { "json_type",            1, 0,   jsonTypeFunc          },
+    { "json_type",            2, 0,   jsonTypeFunc          },
+    { "json_valid",           1, 0,   jsonValidFunc         },
+
+#if SQLITE_DEBUG
+    /* DEBUG and TESTING functions */
+    { "json_parse",           1, 0,   jsonParseFunc         },
+    { "json_test1",           1, 0,   jsonTest1Func         },
+#endif
+  };
+  static const struct {
+     const char *zName;
+     int nArg;
+     void (*xStep)(sqlite3_context*,int,sqlite3_value**);
+     void (*xFinal)(sqlite3_context*);
+  } aAgg[] = {
+    { "json_group_array",     1,   jsonArrayStep,   jsonArrayFinal  },
+    { "json_group_object",    2,   jsonObjectStep,  jsonObjectFinal },
+  };
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  static const struct {
+     const char *zName;
+     sqlite3_module *pModule;
+  } aMod[] = {
+    { "json_each",            &jsonEachModule               },
+    { "json_tree",            &jsonTreeModule               },
+  };
+#endif
+  for(i=0; i<sizeof(aFunc)/sizeof(aFunc[0]) && rc==SQLITE_OK; i++){
+    rc = sqlite3_create_function(db, aFunc[i].zName, aFunc[i].nArg,
+                                 SQLITE_UTF8 | SQLITE_DETERMINISTIC, 
+                                 (void*)&aFunc[i].flag,
+                                 aFunc[i].xFunc, 0, 0);
+  }
+  for(i=0; i<sizeof(aAgg)/sizeof(aAgg[0]) && rc==SQLITE_OK; i++){
+    rc = sqlite3_create_function(db, aAgg[i].zName, aAgg[i].nArg,
+                                 SQLITE_UTF8 | SQLITE_DETERMINISTIC, 0,
+                                 0, aAgg[i].xStep, aAgg[i].xFinal);
+  }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  for(i=0; i<sizeof(aMod)/sizeof(aMod[0]) && rc==SQLITE_OK; i++){
+    rc = sqlite3_create_module(db, aMod[i].zName, aMod[i].pModule, 0);
+  }
+#endif
+  return rc;
+}
+
+
+#ifndef SQLITE_CORE
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+SQLITE_API int sqlite3_json_init(
+  sqlite3 *db, 
+  char **pzErrMsg, 
+  const sqlite3_api_routines *pApi
+){
+  SQLITE_EXTENSION_INIT2(pApi);
+  (void)pzErrMsg;  /* Unused parameter */
+  return sqlite3Json1Init(db);
+}
+#endif
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_JSON1) */
+
+/************** End of json1.c ***********************************************/
+/************** Begin file fts5.c ********************************************/
+
+
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS5) 
+
+#if !defined(NDEBUG) && !defined(SQLITE_DEBUG) 
+# define NDEBUG 1
+#endif
+#if defined(NDEBUG) && defined(SQLITE_DEBUG)
+# undef NDEBUG
+#endif
+
+/*
+** 2014 May 31
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** Interfaces to extend FTS5. Using the interfaces defined in this file, 
+** FTS5 may be extended with:
+**
+**     * custom tokenizers, and
+**     * custom auxiliary functions.
+*/
+
+
+#ifndef _FTS5_H
+#define _FTS5_H
+
+/* #include "sqlite3.h" */
+
+#if 0
+extern "C" {
+#endif
+
+/*************************************************************************
+** CUSTOM AUXILIARY FUNCTIONS
+**
+** Virtual table implementations may overload SQL functions by implementing
+** the sqlite3_module.xFindFunction() method.
+*/
+
+typedef struct Fts5ExtensionApi Fts5ExtensionApi;
+typedef struct Fts5Context Fts5Context;
+typedef struct Fts5PhraseIter Fts5PhraseIter;
+
+typedef void (*fts5_extension_function)(
+  const Fts5ExtensionApi *pApi,   /* API offered by current FTS version */
+  Fts5Context *pFts,              /* First arg to pass to pApi functions */
+  sqlite3_context *pCtx,          /* Context for returning result/error */
+  int nVal,                       /* Number of values in apVal[] array */
+  sqlite3_value **apVal           /* Array of trailing arguments */
+);
+
+struct Fts5PhraseIter {
+  const unsigned char *a;
+  const unsigned char *b;
+};
+
+/*
+** EXTENSION API FUNCTIONS
+**
+** xUserData(pFts):
+**   Return a copy of the context pointer the extension function was 
+**   registered with.
+**
+** xColumnTotalSize(pFts, iCol, pnToken):
+**   If parameter iCol is less than zero, set output variable *pnToken
+**   to the total number of tokens in the FTS5 table. Or, if iCol is
+**   non-negative but less than the number of columns in the table, return
+**   the total number of tokens in column iCol, considering all rows in 
+**   the FTS5 table.
+**
+**   If parameter iCol is greater than or equal to the number of columns
+**   in the table, SQLITE_RANGE is returned. Or, if an error occurs (e.g.
+**   an OOM condition or IO error), an appropriate SQLite error code is 
+**   returned.
+**
+** xColumnCount(pFts):
+**   Return the number of columns in the table.
+**
+** xColumnSize(pFts, iCol, pnToken):
+**   If parameter iCol is less than zero, set output variable *pnToken
+**   to the total number of tokens in the current row. Or, if iCol is
+**   non-negative but less than the number of columns in the table, set
+**   *pnToken to the number of tokens in column iCol of the current row.
+**
+**   If parameter iCol is greater than or equal to the number of columns
+**   in the table, SQLITE_RANGE is returned. Or, if an error occurs (e.g.
+**   an OOM condition or IO error), an appropriate SQLite error code is 
+**   returned.
+**
+**   This function may be quite inefficient if used with an FTS5 table
+**   created with the "columnsize=0" option.
+**
+** xColumnText:
+**   This function attempts to retrieve the text of column iCol of the
+**   current document. If successful, (*pz) is set to point to a buffer
+**   containing the text in utf-8 encoding, (*pn) is set to the size in bytes
+**   (not characters) of the buffer and SQLITE_OK is returned. Otherwise,
+**   if an error occurs, an SQLite error code is returned and the final values
+**   of (*pz) and (*pn) are undefined.
+**
+** xPhraseCount:
+**   Returns the number of phrases in the current query expression.
+**
+** xPhraseSize:
+**   Returns the number of tokens in phrase iPhrase of the query. Phrases
+**   are numbered starting from zero.
+**
+** xInstCount:
+**   Set *pnInst to the total number of occurrences of all phrases within
+**   the query within the current row. Return SQLITE_OK if successful, or
+**   an error code (i.e. SQLITE_NOMEM) if an error occurs.
+**
+**   This API can be quite slow if used with an FTS5 table created with the
+**   "detail=none" or "detail=column" option. If the FTS5 table is created 
+**   with either "detail=none" or "detail=column" and "content=" option 
+**   (i.e. if it is a contentless table), then this API always returns 0.
+**
+** xInst:
+**   Query for the details of phrase match iIdx within the current row.
+**   Phrase matches are numbered starting from zero, so the iIdx argument
+**   should be greater than or equal to zero and smaller than the value
+**   output by xInstCount().
+**
+**   Usually, output parameter *piPhrase is set to the phrase number, *piCol
+**   to the column in which it occurs and *piOff the token offset of the
+**   first token of the phrase. The exception is if the table was created
+**   with the offsets=0 option specified. In this case *piOff is always
+**   set to -1.
+**
+**   Returns SQLITE_OK if successful, or an error code (i.e. SQLITE_NOMEM) 
+**   if an error occurs.
+**
+**   This API can be quite slow if used with an FTS5 table created with the
+**   "detail=none" or "detail=column" option. 
+**
+** xRowid:
+**   Returns the rowid of the current row.
+**
+** xTokenize:
+**   Tokenize text using the tokenizer belonging to the FTS5 table.
+**
+** xQueryPhrase(pFts5, iPhrase, pUserData, xCallback):
+**   This API function is used to query the FTS table for phrase iPhrase
+**   of the current query. Specifically, a query equivalent to:
+**
+**       ... FROM ftstable WHERE ftstable MATCH $p ORDER BY rowid
+**
+**   with $p set to a phrase equivalent to the phrase iPhrase of the
+**   current query is executed. Any column filter that applies to
+**   phrase iPhrase of the current query is included in $p. For each 
+**   row visited, the callback function passed as the fourth argument 
+**   is invoked. The context and API objects passed to the callback 
+**   function may be used to access the properties of each matched row.
+**   Invoking Api.xUserData() returns a copy of the pointer passed as 
+**   the third argument to pUserData.
+**
+**   If the callback function returns any value other than SQLITE_OK, the
+**   query is abandoned and the xQueryPhrase function returns immediately.
+**   If the returned value is SQLITE_DONE, xQueryPhrase returns SQLITE_OK.
+**   Otherwise, the error code is propagated upwards.
+**
+**   If the query runs to completion without incident, SQLITE_OK is returned.
+**   Or, if some error occurs before the query completes or is aborted by
+**   the callback, an SQLite error code is returned.
+**
+**
+** xSetAuxdata(pFts5, pAux, xDelete)
+**
+**   Save the pointer passed as the second argument as the extension functions 
+**   "auxiliary data". The pointer may then be retrieved by the current or any
+**   future invocation of the same fts5 extension function made as part of
+**   of the same MATCH query using the xGetAuxdata() API.
+**
+**   Each extension function is allocated a single auxiliary data slot for
+**   each FTS query (MATCH expression). If the extension function is invoked 
+**   more than once for a single FTS query, then all invocations share a 
+**   single auxiliary data context.
+**
+**   If there is already an auxiliary data pointer when this function is
+**   invoked, then it is replaced by the new pointer. If an xDelete callback
+**   was specified along with the original pointer, it is invoked at this
+**   point.
+**
+**   The xDelete callback, if one is specified, is also invoked on the
+**   auxiliary data pointer after the FTS5 query has finished.
+**
+**   If an error (e.g. an OOM condition) occurs within this function, an
+**   the auxiliary data is set to NULL and an error code returned. If the
+**   xDelete parameter was not NULL, it is invoked on the auxiliary data
+**   pointer before returning.
+**
+**
+** xGetAuxdata(pFts5, bClear)
+**
+**   Returns the current auxiliary data pointer for the fts5 extension 
+**   function. See the xSetAuxdata() method for details.
+**
+**   If the bClear argument is non-zero, then the auxiliary data is cleared
+**   (set to NULL) before this function returns. In this case the xDelete,
+**   if any, is not invoked.
+**
+**
+** xRowCount(pFts5, pnRow)
+**
+**   This function is used to retrieve the total number of rows in the table.
+**   In other words, the same value that would be returned by:
+**
+**        SELECT count(*) FROM ftstable;
+**
+** xPhraseFirst()
+**   This function is used, along with type Fts5PhraseIter and the xPhraseNext
+**   method, to iterate through all instances of a single query phrase within
+**   the current row. This is the same information as is accessible via the
+**   xInstCount/xInst APIs. While the xInstCount/xInst APIs are more convenient
+**   to use, this API may be faster under some circumstances. To iterate 
+**   through instances of phrase iPhrase, use the following code:
+**
+**       Fts5PhraseIter iter;
+**       int iCol, iOff;
+**       for(pApi->xPhraseFirst(pFts, iPhrase, &iter, &iCol, &iOff);
+**           iCol>=0;
+**           pApi->xPhraseNext(pFts, &iter, &iCol, &iOff)
+**       ){
+**         // An instance of phrase iPhrase at offset iOff of column iCol
+**       }
+**
+**   The Fts5PhraseIter structure is defined above. Applications should not
+**   modify this structure directly - it should only be used as shown above
+**   with the xPhraseFirst() and xPhraseNext() API methods (and by
+**   xPhraseFirstColumn() and xPhraseNextColumn() as illustrated below).
+**
+**   This API can be quite slow if used with an FTS5 table created with the
+**   "detail=none" or "detail=column" option. If the FTS5 table is created 
+**   with either "detail=none" or "detail=column" and "content=" option 
+**   (i.e. if it is a contentless table), then this API always iterates
+**   through an empty set (all calls to xPhraseFirst() set iCol to -1).
+**
+** xPhraseNext()
+**   See xPhraseFirst above.
+**
+** xPhraseFirstColumn()
+**   This function and xPhraseNextColumn() are similar to the xPhraseFirst()
+**   and xPhraseNext() APIs described above. The difference is that instead
+**   of iterating through all instances of a phrase in the current row, these
+**   APIs are used to iterate through the set of columns in the current row
+**   that contain one or more instances of a specified phrase. For example:
+**
+**       Fts5PhraseIter iter;
+**       int iCol;
+**       for(pApi->xPhraseFirstColumn(pFts, iPhrase, &iter, &iCol);
+**           iCol>=0;
+**           pApi->xPhraseNextColumn(pFts, &iter, &iCol)
+**       ){
+**         // Column iCol contains at least one instance of phrase iPhrase
+**       }
+**
+**   This API can be quite slow if used with an FTS5 table created with the
+**   "detail=none" option. If the FTS5 table is created with either 
+**   "detail=none" "content=" option (i.e. if it is a contentless table), 
+**   then this API always iterates through an empty set (all calls to 
+**   xPhraseFirstColumn() set iCol to -1).
+**
+**   The information accessed using this API and its companion
+**   xPhraseFirstColumn() may also be obtained using xPhraseFirst/xPhraseNext
+**   (or xInst/xInstCount). The chief advantage of this API is that it is
+**   significantly more efficient than those alternatives when used with
+**   "detail=column" tables.  
+**
+** xPhraseNextColumn()
+**   See xPhraseFirstColumn above.
+*/
+struct Fts5ExtensionApi {
+  int iVersion;                   /* Currently always set to 3 */
+
+  void *(*xUserData)(Fts5Context*);
+
+  int (*xColumnCount)(Fts5Context*);
+  int (*xRowCount)(Fts5Context*, sqlite3_int64 *pnRow);
+  int (*xColumnTotalSize)(Fts5Context*, int iCol, sqlite3_int64 *pnToken);
+
+  int (*xTokenize)(Fts5Context*, 
+    const char *pText, int nText, /* Text to tokenize */
+    void *pCtx,                   /* Context passed to xToken() */
+    int (*xToken)(void*, int, const char*, int, int, int)       /* Callback */
+  );
+
+  int (*xPhraseCount)(Fts5Context*);
+  int (*xPhraseSize)(Fts5Context*, int iPhrase);
+
+  int (*xInstCount)(Fts5Context*, int *pnInst);
+  int (*xInst)(Fts5Context*, int iIdx, int *piPhrase, int *piCol, int *piOff);
+
+  sqlite3_int64 (*xRowid)(Fts5Context*);
+  int (*xColumnText)(Fts5Context*, int iCol, const char **pz, int *pn);
+  int (*xColumnSize)(Fts5Context*, int iCol, int *pnToken);
+
+  int (*xQueryPhrase)(Fts5Context*, int iPhrase, void *pUserData,
+    int(*)(const Fts5ExtensionApi*,Fts5Context*,void*)
+  );
+  int (*xSetAuxdata)(Fts5Context*, void *pAux, void(*xDelete)(void*));
+  void *(*xGetAuxdata)(Fts5Context*, int bClear);
+
+  int (*xPhraseFirst)(Fts5Context*, int iPhrase, Fts5PhraseIter*, int*, int*);
+  void (*xPhraseNext)(Fts5Context*, Fts5PhraseIter*, int *piCol, int *piOff);
+
+  int (*xPhraseFirstColumn)(Fts5Context*, int iPhrase, Fts5PhraseIter*, int*);
+  void (*xPhraseNextColumn)(Fts5Context*, Fts5PhraseIter*, int *piCol);
+};
+
+/* 
+** CUSTOM AUXILIARY FUNCTIONS
+*************************************************************************/
+
+/*************************************************************************
+** CUSTOM TOKENIZERS
+**
+** Applications may also register custom tokenizer types. A tokenizer 
+** is registered by providing fts5 with a populated instance of the 
+** following structure. All structure methods must be defined, setting
+** any member of the fts5_tokenizer struct to NULL leads to undefined
+** behaviour. The structure methods are expected to function as follows:
+**
+** xCreate:
+**   This function is used to allocate and initialize a tokenizer instance.
+**   A tokenizer instance is required to actually tokenize text.
+**
+**   The first argument passed to this function is a copy of the (void*)
+**   pointer provided by the application when the fts5_tokenizer object
+**   was registered with FTS5 (the third argument to xCreateTokenizer()). 
+**   The second and third arguments are an array of nul-terminated strings
+**   containing the tokenizer arguments, if any, specified following the
+**   tokenizer name as part of the CREATE VIRTUAL TABLE statement used
+**   to create the FTS5 table.
+**
+**   The final argument is an output variable. If successful, (*ppOut) 
+**   should be set to point to the new tokenizer handle and SQLITE_OK
+**   returned. If an error occurs, some value other than SQLITE_OK should
+**   be returned. In this case, fts5 assumes that the final value of *ppOut 
+**   is undefined.
+**
+** xDelete:
+**   This function is invoked to delete a tokenizer handle previously
+**   allocated using xCreate(). Fts5 guarantees that this function will
+**   be invoked exactly once for each successful call to xCreate().
+**
+** xTokenize:
+**   This function is expected to tokenize the nText byte string indicated 
+**   by argument pText. pText may or may not be nul-terminated. The first
+**   argument passed to this function is a pointer to an Fts5Tokenizer object
+**   returned by an earlier call to xCreate().
+**
+**   The second argument indicates the reason that FTS5 is requesting
+**   tokenization of the supplied text. This is always one of the following
+**   four values:
+**
+**   <ul><li> <b>FTS5_TOKENIZE_DOCUMENT</b> - A document is being inserted into
+**            or removed from the FTS table. The tokenizer is being invoked to
+**            determine the set of tokens to add to (or delete from) the
+**            FTS index.
+**
+**       <li> <b>FTS5_TOKENIZE_QUERY</b> - A MATCH query is being executed 
+**            against the FTS index. The tokenizer is being called to tokenize 
+**            a bareword or quoted string specified as part of the query.
+**
+**       <li> <b>(FTS5_TOKENIZE_QUERY | FTS5_TOKENIZE_PREFIX)</b> - Same as
+**            FTS5_TOKENIZE_QUERY, except that the bareword or quoted string is
+**            followed by a "*" character, indicating that the last token
+**            returned by the tokenizer will be treated as a token prefix.
+**
+**       <li> <b>FTS5_TOKENIZE_AUX</b> - The tokenizer is being invoked to 
+**            satisfy an fts5_api.xTokenize() request made by an auxiliary
+**            function. Or an fts5_api.xColumnSize() request made by the same
+**            on a columnsize=0 database.  
+**   </ul>
+**
+**   For each token in the input string, the supplied callback xToken() must
+**   be invoked. The first argument to it should be a copy of the pointer
+**   passed as the second argument to xTokenize(). The third and fourth
+**   arguments are a pointer to a buffer containing the token text, and the
+**   size of the token in bytes. The 4th and 5th arguments are the byte offsets
+**   of the first byte of and first byte immediately following the text from
+**   which the token is derived within the input.
+**
+**   The second argument passed to the xToken() callback ("tflags") should
+**   normally be set to 0. The exception is if the tokenizer supports 
+**   synonyms. In this case see the discussion below for details.
+**
+**   FTS5 assumes the xToken() callback is invoked for each token in the 
+**   order that they occur within the input text.
+**
+**   If an xToken() callback returns any value other than SQLITE_OK, then
+**   the tokenization should be abandoned and the xTokenize() method should
+**   immediately return a copy of the xToken() return value. Or, if the
+**   input buffer is exhausted, xTokenize() should return SQLITE_OK. Finally,
+**   if an error occurs with the xTokenize() implementation itself, it
+**   may abandon the tokenization and return any error code other than
+**   SQLITE_OK or SQLITE_DONE.
+**
+** SYNONYM SUPPORT
+**
+**   Custom tokenizers may also support synonyms. Consider a case in which a
+**   user wishes to query for a phrase such as "first place". Using the 
+**   built-in tokenizers, the FTS5 query 'first + place' will match instances
+**   of "first place" within the document set, but not alternative forms
+**   such as "1st place". In some applications, it would be better to match
+**   all instances of "first place" or "1st place" regardless of which form
+**   the user specified in the MATCH query text.
+**
+**   There are several ways to approach this in FTS5:
+**
+**   <ol><li> By mapping all synonyms to a single token. In this case, the 
+**            In the above example, this means that the tokenizer returns the
+**            same token for inputs "first" and "1st". Say that token is in
+**            fact "first", so that when the user inserts the document "I won
+**            1st place" entries are added to the index for tokens "i", "won",
+**            "first" and "place". If the user then queries for '1st + place',
+**            the tokenizer substitutes "first" for "1st" and the query works
+**            as expected.
+**
+**       <li> By adding multiple synonyms for a single term to the FTS index.
+**            In this case, when tokenizing query text, the tokenizer may 
+**            provide multiple synonyms for a single term within the document.
+**            FTS5 then queries the index for each synonym individually. For
+**            example, faced with the query:
+**
+**   <codeblock>
+**     ... MATCH 'first place'</codeblock>
+**
+**            the tokenizer offers both "1st" and "first" as synonyms for the
+**            first token in the MATCH query and FTS5 effectively runs a query 
+**            similar to:
+**
+**   <codeblock>
+**     ... MATCH '(first OR 1st) place'</codeblock>
+**
+**            except that, for the purposes of auxiliary functions, the query
+**            still appears to contain just two phrases - "(first OR 1st)" 
+**            being treated as a single phrase.
+**
+**       <li> By adding multiple synonyms for a single term to the FTS index.
+**            Using this method, when tokenizing document text, the tokenizer
+**            provides multiple synonyms for each token. So that when a 
+**            document such as "I won first place" is tokenized, entries are
+**            added to the FTS index for "i", "won", "first", "1st" and
+**            "place".
+**
+**            This way, even if the tokenizer does not provide synonyms
+**            when tokenizing query text (it should not - to do would be
+**            inefficient), it doesn't matter if the user queries for 
+**            'first + place' or '1st + place', as there are entires in the
+**            FTS index corresponding to both forms of the first token.
+**   </ol>
+**
+**   Whether it is parsing document or query text, any call to xToken that
+**   specifies a <i>tflags</i> argument with the FTS5_TOKEN_COLOCATED bit
+**   is considered to supply a synonym for the previous token. For example,
+**   when parsing the document "I won first place", a tokenizer that supports
+**   synonyms would call xToken() 5 times, as follows:
+**
+**   <codeblock>
+**       xToken(pCtx, 0, "i",                      1,  0,  1);
+**       xToken(pCtx, 0, "won",                    3,  2,  5);
+**       xToken(pCtx, 0, "first",                  5,  6, 11);
+**       xToken(pCtx, FTS5_TOKEN_COLOCATED, "1st", 3,  6, 11);
+**       xToken(pCtx, 0, "place",                  5, 12, 17);
+**</codeblock>
+**
+**   It is an error to specify the FTS5_TOKEN_COLOCATED flag the first time
+**   xToken() is called. Multiple synonyms may be specified for a single token
+**   by making multiple calls to xToken(FTS5_TOKEN_COLOCATED) in sequence. 
+**   There is no limit to the number of synonyms that may be provided for a
+**   single token.
+**
+**   In many cases, method (1) above is the best approach. It does not add 
+**   extra data to the FTS index or require FTS5 to query for multiple terms,
+**   so it is efficient in terms of disk space and query speed. However, it
+**   does not support prefix queries very well. If, as suggested above, the
+**   token "first" is subsituted for "1st" by the tokenizer, then the query:
+**
+**   <codeblock>
+**     ... MATCH '1s*'</codeblock>
+**
+**   will not match documents that contain the token "1st" (as the tokenizer
+**   will probably not map "1s" to any prefix of "first").
+**
+**   For full prefix support, method (3) may be preferred. In this case, 
+**   because the index contains entries for both "first" and "1st", prefix
+**   queries such as 'fi*' or '1s*' will match correctly. However, because
+**   extra entries are added to the FTS index, this method uses more space
+**   within the database.
+**
+**   Method (2) offers a midpoint between (1) and (3). Using this method,
+**   a query such as '1s*' will match documents that contain the literal 
+**   token "1st", but not "first" (assuming the tokenizer is not able to
+**   provide synonyms for prefixes). However, a non-prefix query like '1st'
+**   will match against "1st" and "first". This method does not require
+**   extra disk space, as no extra entries are added to the FTS index. 
+**   On the other hand, it may require more CPU cycles to run MATCH queries,
+**   as separate queries of the FTS index are required for each synonym.
+**
+**   When using methods (2) or (3), it is important that the tokenizer only
+**   provide synonyms when tokenizing document text (method (2)) or query
+**   text (method (3)), not both. Doing so will not cause any errors, but is
+**   inefficient.
+*/
+typedef struct Fts5Tokenizer Fts5Tokenizer;
+typedef struct fts5_tokenizer fts5_tokenizer;
+struct fts5_tokenizer {
+  int (*xCreate)(void*, const char **azArg, int nArg, Fts5Tokenizer **ppOut);
+  void (*xDelete)(Fts5Tokenizer*);
+  int (*xTokenize)(Fts5Tokenizer*, 
+      void *pCtx,
+      int flags,            /* Mask of FTS5_TOKENIZE_* flags */
+      const char *pText, int nText, 
+      int (*xToken)(
+        void *pCtx,         /* Copy of 2nd argument to xTokenize() */
+        int tflags,         /* Mask of FTS5_TOKEN_* flags */
+        const char *pToken, /* Pointer to buffer containing token */
+        int nToken,         /* Size of token in bytes */
+        int iStart,         /* Byte offset of token within input text */
+        int iEnd            /* Byte offset of end of token within input text */
+      )
+  );
+};
+
+/* Flags that may be passed as the third argument to xTokenize() */
+#define FTS5_TOKENIZE_QUERY     0x0001
+#define FTS5_TOKENIZE_PREFIX    0x0002
+#define FTS5_TOKENIZE_DOCUMENT  0x0004
+#define FTS5_TOKENIZE_AUX       0x0008
+
+/* Flags that may be passed by the tokenizer implementation back to FTS5
+** as the third argument to the supplied xToken callback. */
+#define FTS5_TOKEN_COLOCATED    0x0001      /* Same position as prev. token */
+
+/*
+** END OF CUSTOM TOKENIZERS
+*************************************************************************/
+
+/*************************************************************************
+** FTS5 EXTENSION REGISTRATION API
+*/
+typedef struct fts5_api fts5_api;
+struct fts5_api {
+  int iVersion;                   /* Currently always set to 2 */
+
+  /* Create a new tokenizer */
+  int (*xCreateTokenizer)(
+    fts5_api *pApi,
+    const char *zName,
+    void *pContext,
+    fts5_tokenizer *pTokenizer,
+    void (*xDestroy)(void*)
+  );
+
+  /* Find an existing tokenizer */
+  int (*xFindTokenizer)(
+    fts5_api *pApi,
+    const char *zName,
+    void **ppContext,
+    fts5_tokenizer *pTokenizer
+  );
+
+  /* Create a new auxiliary function */
+  int (*xCreateFunction)(
+    fts5_api *pApi,
+    const char *zName,
+    void *pContext,
+    fts5_extension_function xFunction,
+    void (*xDestroy)(void*)
+  );
+};
+
+/*
+** END OF REGISTRATION API
+*************************************************************************/
+
+#if 0
+}  /* end of the 'extern "C"' block */
+#endif
+
+#endif /* _FTS5_H */
+
+/*
+** 2014 May 31
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+*/
+#ifndef _FTS5INT_H
+#define _FTS5INT_H
+
+/* #include "fts5.h" */
+/* #include "sqlite3ext.h" */
+SQLITE_EXTENSION_INIT1
+
+/* #include <string.h> */
+/* #include <assert.h> */
+
+#ifndef SQLITE_AMALGAMATION
+
+typedef unsigned char  u8;
+typedef unsigned int   u32;
+typedef unsigned short u16;
+typedef short i16;
+typedef sqlite3_int64 i64;
+typedef sqlite3_uint64 u64;
+
+#define ArraySize(x) ((int)(sizeof(x) / sizeof(x[0])))
+
+#define testcase(x)
+#define ALWAYS(x) 1
+#define NEVER(x) 0
+
+#define MIN(x,y) (((x) < (y)) ? (x) : (y))
+#define MAX(x,y) (((x) > (y)) ? (x) : (y))
+
+/*
+** Constants for the largest and smallest possible 64-bit signed integers.
+*/
+# define LARGEST_INT64  (0xffffffff|(((i64)0x7fffffff)<<32))
+# define SMALLEST_INT64 (((i64)-1) - LARGEST_INT64)
+
+#endif
+
+/* Truncate very long tokens to this many bytes. Hard limit is 
+** (65536-1-1-4-9)==65521 bytes. The limiting factor is the 16-bit offset
+** field that occurs at the start of each leaf page (see fts5_index.c). */
+#define FTS5_MAX_TOKEN_SIZE 32768
+
+/*
+** Maximum number of prefix indexes on single FTS5 table. This must be
+** less than 32. If it is set to anything large than that, an #error
+** directive in fts5_index.c will cause the build to fail.
+*/
+#define FTS5_MAX_PREFIX_INDEXES 31
+
+#define FTS5_DEFAULT_NEARDIST 10
+#define FTS5_DEFAULT_RANK     "bm25"
+
+/* Name of rank and rowid columns */
+#define FTS5_RANK_NAME "rank"
+#define FTS5_ROWID_NAME "rowid"
+
+#ifdef SQLITE_DEBUG
+# define FTS5_CORRUPT sqlite3Fts5Corrupt()
+static int sqlite3Fts5Corrupt(void);
+#else
+# define FTS5_CORRUPT SQLITE_CORRUPT_VTAB
+#endif
+
+/*
+** The assert_nc() macro is similar to the assert() macro, except that it
+** is used for assert() conditions that are true only if it can be 
+** guranteed that the database is not corrupt.
+*/
+#ifdef SQLITE_DEBUG
+SQLITE_API extern int sqlite3_fts5_may_be_corrupt;
+# define assert_nc(x) assert(sqlite3_fts5_may_be_corrupt || (x))
+#else
+# define assert_nc(x) assert(x)
+#endif
+
+/* Mark a function parameter as unused, to suppress nuisance compiler
+** warnings. */
+#ifndef UNUSED_PARAM
+# define UNUSED_PARAM(X)  (void)(X)
+#endif
+
+#ifndef UNUSED_PARAM2
+# define UNUSED_PARAM2(X, Y)  (void)(X), (void)(Y)
+#endif
+
+typedef struct Fts5Global Fts5Global;
+typedef struct Fts5Colset Fts5Colset;
+
+/* If a NEAR() clump or phrase may only match a specific set of columns, 
+** then an object of the following type is used to record the set of columns.
+** Each entry in the aiCol[] array is a column that may be matched.
+**
+** This object is used by fts5_expr.c and fts5_index.c.
+*/
+struct Fts5Colset {
+  int nCol;
+  int aiCol[1];
+};
+
+
+
+/**************************************************************************
+** Interface to code in fts5_config.c. fts5_config.c contains contains code
+** to parse the arguments passed to the CREATE VIRTUAL TABLE statement.
+*/
+
+typedef struct Fts5Config Fts5Config;
+
+/*
+** An instance of the following structure encodes all information that can
+** be gleaned from the CREATE VIRTUAL TABLE statement.
+**
+** And all information loaded from the %_config table.
+**
+** nAutomerge:
+**   The minimum number of segments that an auto-merge operation should
+**   attempt to merge together. A value of 1 sets the object to use the 
+**   compile time default. Zero disables auto-merge altogether.
+**
+** zContent:
+**
+** zContentRowid:
+**   The value of the content_rowid= option, if one was specified. Or 
+**   the string "rowid" otherwise. This text is not quoted - if it is
+**   used as part of an SQL statement it needs to be quoted appropriately.
+**
+** zContentExprlist:
+**
+** pzErrmsg:
+**   This exists in order to allow the fts5_index.c module to return a 
+**   decent error message if it encounters a file-format version it does
+**   not understand.
+**
+** bColumnsize:
+**   True if the %_docsize table is created.
+**
+** bPrefixIndex:
+**   This is only used for debugging. If set to false, any prefix indexes
+**   are ignored. This value is configured using:
+**
+**       INSERT INTO tbl(tbl, rank) VALUES('prefix-index', $bPrefixIndex);
+**
+*/
+struct Fts5Config {
+  sqlite3 *db;                    /* Database handle */
+  char *zDb;                      /* Database holding FTS index (e.g. "main") */
+  char *zName;                    /* Name of FTS index */
+  int nCol;                       /* Number of columns */
+  char **azCol;                   /* Column names */
+  u8 *abUnindexed;                /* True for unindexed columns */
+  int nPrefix;                    /* Number of prefix indexes */
+  int *aPrefix;                   /* Sizes in bytes of nPrefix prefix indexes */
+  int eContent;                   /* An FTS5_CONTENT value */
+  char *zContent;                 /* content table */ 
+  char *zContentRowid;            /* "content_rowid=" option value */ 
+  int bColumnsize;                /* "columnsize=" option value (dflt==1) */
+  int eDetail;                    /* FTS5_DETAIL_XXX value */
+  char *zContentExprlist;
+  Fts5Tokenizer *pTok;
+  fts5_tokenizer *pTokApi;
+
+  /* Values loaded from the %_config table */
+  int iCookie;                    /* Incremented when %_config is modified */
+  int pgsz;                       /* Approximate page size used in %_data */
+  int nAutomerge;                 /* 'automerge' setting */
+  int nCrisisMerge;               /* Maximum allowed segments per level */
+  int nUsermerge;                 /* 'usermerge' setting */
+  int nHashSize;                  /* Bytes of memory for in-memory hash */
+  char *zRank;                    /* Name of rank function */
+  char *zRankArgs;                /* Arguments to rank function */
+
+  /* If non-NULL, points to sqlite3_vtab.base.zErrmsg. Often NULL. */
+  char **pzErrmsg;
+
+#ifdef SQLITE_DEBUG
+  int bPrefixIndex;               /* True to use prefix-indexes */
+#endif
+};
+
+/* Current expected value of %_config table 'version' field */
+#define FTS5_CURRENT_VERSION 4
+
+#define FTS5_CONTENT_NORMAL   0
+#define FTS5_CONTENT_NONE     1
+#define FTS5_CONTENT_EXTERNAL 2
+
+#define FTS5_DETAIL_FULL    0
+#define FTS5_DETAIL_NONE    1
+#define FTS5_DETAIL_COLUMNS 2
+
+
+
+static int sqlite3Fts5ConfigParse(
+    Fts5Global*, sqlite3*, int, const char **, Fts5Config**, char**
+);
+static void sqlite3Fts5ConfigFree(Fts5Config*);
+
+static int sqlite3Fts5ConfigDeclareVtab(Fts5Config *pConfig);
+
+static int sqlite3Fts5Tokenize(
+  Fts5Config *pConfig,            /* FTS5 Configuration object */
+  int flags,                      /* FTS5_TOKENIZE_* flags */
+  const char *pText, int nText,   /* Text to tokenize */
+  void *pCtx,                     /* Context passed to xToken() */
+  int (*xToken)(void*, int, const char*, int, int, int)    /* Callback */
+);
+
+static void sqlite3Fts5Dequote(char *z);
+
+/* Load the contents of the %_config table */
+static int sqlite3Fts5ConfigLoad(Fts5Config*, int);
+
+/* Set the value of a single config attribute */
+static int sqlite3Fts5ConfigSetValue(Fts5Config*, const char*, sqlite3_value*, int*);
+
+static int sqlite3Fts5ConfigParseRank(const char*, char**, char**);
+
+/*
+** End of interface to code in fts5_config.c.
+**************************************************************************/
+
+/**************************************************************************
+** Interface to code in fts5_buffer.c.
+*/
+
+/*
+** Buffer object for the incremental building of string data.
+*/
+typedef struct Fts5Buffer Fts5Buffer;
+struct Fts5Buffer {
+  u8 *p;
+  int n;
+  int nSpace;
+};
+
+static int sqlite3Fts5BufferSize(int*, Fts5Buffer*, u32);
+static void sqlite3Fts5BufferAppendVarint(int*, Fts5Buffer*, i64);
+static void sqlite3Fts5BufferAppendBlob(int*, Fts5Buffer*, u32, const u8*);
+static void sqlite3Fts5BufferAppendString(int *, Fts5Buffer*, const char*);
+static void sqlite3Fts5BufferFree(Fts5Buffer*);
+static void sqlite3Fts5BufferZero(Fts5Buffer*);
+static void sqlite3Fts5BufferSet(int*, Fts5Buffer*, int, const u8*);
+static void sqlite3Fts5BufferAppendPrintf(int *, Fts5Buffer*, char *zFmt, ...);
+
+static char *sqlite3Fts5Mprintf(int *pRc, const char *zFmt, ...);
+
+#define fts5BufferZero(x)             sqlite3Fts5BufferZero(x)
+#define fts5BufferAppendVarint(a,b,c) sqlite3Fts5BufferAppendVarint(a,b,c)
+#define fts5BufferFree(a)             sqlite3Fts5BufferFree(a)
+#define fts5BufferAppendBlob(a,b,c,d) sqlite3Fts5BufferAppendBlob(a,b,c,d)
+#define fts5BufferSet(a,b,c,d)        sqlite3Fts5BufferSet(a,b,c,d)
+
+#define fts5BufferGrow(pRc,pBuf,nn) ( \
+  (u32)((pBuf)->n) + (u32)(nn) <= (u32)((pBuf)->nSpace) ? 0 : \
+    sqlite3Fts5BufferSize((pRc),(pBuf),(nn)+(pBuf)->n) \
+)
+
+/* Write and decode big-endian 32-bit integer values */
+static void sqlite3Fts5Put32(u8*, int);
+static int sqlite3Fts5Get32(const u8*);
+
+#define FTS5_POS2COLUMN(iPos) (int)(iPos >> 32)
+#define FTS5_POS2OFFSET(iPos) (int)(iPos & 0xFFFFFFFF)
+
+typedef struct Fts5PoslistReader Fts5PoslistReader;
+struct Fts5PoslistReader {
+  /* Variables used only by sqlite3Fts5PoslistIterXXX() functions. */
+  const u8 *a;                    /* Position list to iterate through */
+  int n;                          /* Size of buffer at a[] in bytes */
+  int i;                          /* Current offset in a[] */
+
+  u8 bFlag;                       /* For client use (any custom purpose) */
+
+  /* Output variables */
+  u8 bEof;                        /* Set to true at EOF */
+  i64 iPos;                       /* (iCol<<32) + iPos */
+};
+static int sqlite3Fts5PoslistReaderInit(
+  const u8 *a, int n,             /* Poslist buffer to iterate through */
+  Fts5PoslistReader *pIter        /* Iterator object to initialize */
+);
+static int sqlite3Fts5PoslistReaderNext(Fts5PoslistReader*);
+
+typedef struct Fts5PoslistWriter Fts5PoslistWriter;
+struct Fts5PoslistWriter {
+  i64 iPrev;
+};
+static int sqlite3Fts5PoslistWriterAppend(Fts5Buffer*, Fts5PoslistWriter*, i64);
+static void sqlite3Fts5PoslistSafeAppend(Fts5Buffer*, i64*, i64);
+
+static int sqlite3Fts5PoslistNext64(
+  const u8 *a, int n,             /* Buffer containing poslist */
+  int *pi,                        /* IN/OUT: Offset within a[] */
+  i64 *piOff                      /* IN/OUT: Current offset */
+);
+
+/* Malloc utility */
+static void *sqlite3Fts5MallocZero(int *pRc, int nByte);
+static char *sqlite3Fts5Strndup(int *pRc, const char *pIn, int nIn);
+
+/* Character set tests (like isspace(), isalpha() etc.) */
+static int sqlite3Fts5IsBareword(char t);
+
+
+/* Bucket of terms object used by the integrity-check in offsets=0 mode. */
+typedef struct Fts5Termset Fts5Termset;
+static int sqlite3Fts5TermsetNew(Fts5Termset**);
+static int sqlite3Fts5TermsetAdd(Fts5Termset*, int, const char*, int, int *pbPresent);
+static void sqlite3Fts5TermsetFree(Fts5Termset*);
+
+/*
+** End of interface to code in fts5_buffer.c.
+**************************************************************************/
+
+/**************************************************************************
+** Interface to code in fts5_index.c. fts5_index.c contains contains code
+** to access the data stored in the %_data table.
+*/
+
+typedef struct Fts5Index Fts5Index;
+typedef struct Fts5IndexIter Fts5IndexIter;
+
+struct Fts5IndexIter {
+  i64 iRowid;
+  const u8 *pData;
+  int nData;
+  u8 bEof;
+};
+
+#define sqlite3Fts5IterEof(x) ((x)->bEof)
+
+/*
+** Values used as part of the flags argument passed to IndexQuery().
+*/
+#define FTS5INDEX_QUERY_PREFIX     0x0001   /* Prefix query */
+#define FTS5INDEX_QUERY_DESC       0x0002   /* Docs in descending rowid order */
+#define FTS5INDEX_QUERY_TEST_NOIDX 0x0004   /* Do not use prefix index */
+#define FTS5INDEX_QUERY_SCAN       0x0008   /* Scan query (fts5vocab) */
+
+/* The following are used internally by the fts5_index.c module. They are
+** defined here only to make it easier to avoid clashes with the flags
+** above. */
+#define FTS5INDEX_QUERY_SKIPEMPTY  0x0010
+#define FTS5INDEX_QUERY_NOOUTPUT   0x0020
+
+/*
+** Create/destroy an Fts5Index object.
+*/
+static int sqlite3Fts5IndexOpen(Fts5Config *pConfig, int bCreate, Fts5Index**, char**);
+static int sqlite3Fts5IndexClose(Fts5Index *p);
+
+/*
+** Return a simple checksum value based on the arguments.
+*/
+static u64 sqlite3Fts5IndexEntryCksum(
+  i64 iRowid, 
+  int iCol, 
+  int iPos, 
+  int iIdx,
+  const char *pTerm,
+  int nTerm
+);
+
+/*
+** Argument p points to a buffer containing utf-8 text that is n bytes in 
+** size. Return the number of bytes in the nChar character prefix of the
+** buffer, or 0 if there are less than nChar characters in total.
+*/
+static int sqlite3Fts5IndexCharlenToBytelen(
+  const char *p, 
+  int nByte, 
+  int nChar
+);
+
+/*
+** Open a new iterator to iterate though all rowids that match the 
+** specified token or token prefix.
+*/
+static int sqlite3Fts5IndexQuery(
+  Fts5Index *p,                   /* FTS index to query */
+  const char *pToken, int nToken, /* Token (or prefix) to query for */
+  int flags,                      /* Mask of FTS5INDEX_QUERY_X flags */
+  Fts5Colset *pColset,            /* Match these columns only */
+  Fts5IndexIter **ppIter          /* OUT: New iterator object */
+);
+
+/*
+** The various operations on open token or token prefix iterators opened
+** using sqlite3Fts5IndexQuery().
+*/
+static int sqlite3Fts5IterNext(Fts5IndexIter*);
+static int sqlite3Fts5IterNextFrom(Fts5IndexIter*, i64 iMatch);
+
+/*
+** Close an iterator opened by sqlite3Fts5IndexQuery().
+*/
+static void sqlite3Fts5IterClose(Fts5IndexIter*);
+
+/*
+** This interface is used by the fts5vocab module.
+*/
+static const char *sqlite3Fts5IterTerm(Fts5IndexIter*, int*);
+static int sqlite3Fts5IterNextScan(Fts5IndexIter*);
+
+
+/*
+** Insert or remove data to or from the index. Each time a document is 
+** added to or removed from the index, this function is called one or more
+** times.
+**
+** For an insert, it must be called once for each token in the new document.
+** If the operation is a delete, it must be called (at least) once for each
+** unique token in the document with an iCol value less than zero. The iPos
+** argument is ignored for a delete.
+*/
+static int sqlite3Fts5IndexWrite(
+  Fts5Index *p,                   /* Index to write to */
+  int iCol,                       /* Column token appears in (-ve -> delete) */
+  int iPos,                       /* Position of token within column */
+  const char *pToken, int nToken  /* Token to add or remove to or from index */
+);
+
+/*
+** Indicate that subsequent calls to sqlite3Fts5IndexWrite() pertain to
+** document iDocid.
+*/
+static int sqlite3Fts5IndexBeginWrite(
+  Fts5Index *p,                   /* Index to write to */
+  int bDelete,                    /* True if current operation is a delete */
+  i64 iDocid                      /* Docid to add or remove data from */
+);
+
+/*
+** Flush any data stored in the in-memory hash tables to the database.
+** If the bCommit flag is true, also close any open blob handles.
+*/
+static int sqlite3Fts5IndexSync(Fts5Index *p, int bCommit);
+
+/*
+** Discard any data stored in the in-memory hash tables. Do not write it
+** to the database. Additionally, assume that the contents of the %_data
+** table may have changed on disk. So any in-memory caches of %_data 
+** records must be invalidated.
+*/
+static int sqlite3Fts5IndexRollback(Fts5Index *p);
+
+/*
+** Get or set the "averages" values.
+*/
+static int sqlite3Fts5IndexGetAverages(Fts5Index *p, i64 *pnRow, i64 *anSize);
+static int sqlite3Fts5IndexSetAverages(Fts5Index *p, const u8*, int);
+
+/*
+** Functions called by the storage module as part of integrity-check.
+*/
+static int sqlite3Fts5IndexIntegrityCheck(Fts5Index*, u64 cksum);
+
+/* 
+** Called during virtual module initialization to register UDF 
+** fts5_decode() with SQLite 
+*/
+static int sqlite3Fts5IndexInit(sqlite3*);
+
+static int sqlite3Fts5IndexSetCookie(Fts5Index*, int);
+
+/*
+** Return the total number of entries read from the %_data table by 
+** this connection since it was created.
+*/
+static int sqlite3Fts5IndexReads(Fts5Index *p);
+
+static int sqlite3Fts5IndexReinit(Fts5Index *p);
+static int sqlite3Fts5IndexOptimize(Fts5Index *p);
+static int sqlite3Fts5IndexMerge(Fts5Index *p, int nMerge);
+static int sqlite3Fts5IndexReset(Fts5Index *p);
+
+static int sqlite3Fts5IndexLoadConfig(Fts5Index *p);
+
+/*
+** End of interface to code in fts5_index.c.
+**************************************************************************/
+
+/**************************************************************************
+** Interface to code in fts5_varint.c. 
+*/
+static int sqlite3Fts5GetVarint32(const unsigned char *p, u32 *v);
+static int sqlite3Fts5GetVarintLen(u32 iVal);
+static u8 sqlite3Fts5GetVarint(const unsigned char*, u64*);
+static int sqlite3Fts5PutVarint(unsigned char *p, u64 v);
+
+#define fts5GetVarint32(a,b) sqlite3Fts5GetVarint32(a,(u32*)&b)
+#define fts5GetVarint    sqlite3Fts5GetVarint
+
+#define fts5FastGetVarint32(a, iOff, nVal) {      \
+  nVal = (a)[iOff++];                             \
+  if( nVal & 0x80 ){                              \
+    iOff--;                                       \
+    iOff += fts5GetVarint32(&(a)[iOff], nVal);    \
+  }                                               \
+}
+
+
+/*
+** End of interface to code in fts5_varint.c.
+**************************************************************************/
+
+
+/**************************************************************************
+** Interface to code in fts5.c. 
+*/
+
+static int sqlite3Fts5GetTokenizer(
+  Fts5Global*, 
+  const char **azArg,
+  int nArg,
+  Fts5Tokenizer**,
+  fts5_tokenizer**,
+  char **pzErr
+);
+
+static Fts5Index *sqlite3Fts5IndexFromCsrid(Fts5Global*, i64, Fts5Config **);
+
+/*
+** End of interface to code in fts5.c.
+**************************************************************************/
+
+/**************************************************************************
+** Interface to code in fts5_hash.c. 
+*/
+typedef struct Fts5Hash Fts5Hash;
+
+/*
+** Create a hash table, free a hash table.
+*/
+static int sqlite3Fts5HashNew(Fts5Config*, Fts5Hash**, int *pnSize);
+static void sqlite3Fts5HashFree(Fts5Hash*);
+
+static int sqlite3Fts5HashWrite(
+  Fts5Hash*,
+  i64 iRowid,                     /* Rowid for this entry */
+  int iCol,                       /* Column token appears in (-ve -> delete) */
+  int iPos,                       /* Position of token within column */
+  char bByte,
+  const char *pToken, int nToken  /* Token to add or remove to or from index */
+);
+
+/*
+** Empty (but do not delete) a hash table.
+*/
+static void sqlite3Fts5HashClear(Fts5Hash*);
+
+static int sqlite3Fts5HashQuery(
+  Fts5Hash*,                      /* Hash table to query */
+  const char *pTerm, int nTerm,   /* Query term */
+  const u8 **ppDoclist,           /* OUT: Pointer to doclist for pTerm */
+  int *pnDoclist                  /* OUT: Size of doclist in bytes */
+);
+
+static int sqlite3Fts5HashScanInit(
+  Fts5Hash*,                      /* Hash table to query */
+  const char *pTerm, int nTerm    /* Query prefix */
+);
+static void sqlite3Fts5HashScanNext(Fts5Hash*);
+static int sqlite3Fts5HashScanEof(Fts5Hash*);
+static void sqlite3Fts5HashScanEntry(Fts5Hash *,
+  const char **pzTerm,            /* OUT: term (nul-terminated) */
+  const u8 **ppDoclist,           /* OUT: pointer to doclist */
+  int *pnDoclist                  /* OUT: size of doclist in bytes */
+);
+
+
+/*
+** End of interface to code in fts5_hash.c.
+**************************************************************************/
+
+/**************************************************************************
+** Interface to code in fts5_storage.c. fts5_storage.c contains contains 
+** code to access the data stored in the %_content and %_docsize tables.
+*/
+
+#define FTS5_STMT_SCAN_ASC  0     /* SELECT rowid, * FROM ... ORDER BY 1 ASC */
+#define FTS5_STMT_SCAN_DESC 1     /* SELECT rowid, * FROM ... ORDER BY 1 DESC */
+#define FTS5_STMT_LOOKUP    2     /* SELECT rowid, * FROM ... WHERE rowid=? */
+
+typedef struct Fts5Storage Fts5Storage;
+
+static int sqlite3Fts5StorageOpen(Fts5Config*, Fts5Index*, int, Fts5Storage**, char**);
+static int sqlite3Fts5StorageClose(Fts5Storage *p);
+static int sqlite3Fts5StorageRename(Fts5Storage*, const char *zName);
+
+static int sqlite3Fts5DropAll(Fts5Config*);
+static int sqlite3Fts5CreateTable(Fts5Config*, const char*, const char*, int, char **);
+
+static int sqlite3Fts5StorageDelete(Fts5Storage *p, i64, sqlite3_value**);
+static int sqlite3Fts5StorageContentInsert(Fts5Storage *p, sqlite3_value**, i64*);
+static int sqlite3Fts5StorageIndexInsert(Fts5Storage *p, sqlite3_value**, i64);
+
+static int sqlite3Fts5StorageIntegrity(Fts5Storage *p);
+
+static int sqlite3Fts5StorageStmt(Fts5Storage *p, int eStmt, sqlite3_stmt**, char**);
+static void sqlite3Fts5StorageStmtRelease(Fts5Storage *p, int eStmt, sqlite3_stmt*);
+
+static int sqlite3Fts5StorageDocsize(Fts5Storage *p, i64 iRowid, int *aCol);
+static int sqlite3Fts5StorageSize(Fts5Storage *p, int iCol, i64 *pnAvg);
+static int sqlite3Fts5StorageRowCount(Fts5Storage *p, i64 *pnRow);
+
+static int sqlite3Fts5StorageSync(Fts5Storage *p, int bCommit);
+static int sqlite3Fts5StorageRollback(Fts5Storage *p);
+
+static int sqlite3Fts5StorageConfigValue(
+    Fts5Storage *p, const char*, sqlite3_value*, int
+);
+
+static int sqlite3Fts5StorageDeleteAll(Fts5Storage *p);
+static int sqlite3Fts5StorageRebuild(Fts5Storage *p);
+static int sqlite3Fts5StorageOptimize(Fts5Storage *p);
+static int sqlite3Fts5StorageMerge(Fts5Storage *p, int nMerge);
+static int sqlite3Fts5StorageReset(Fts5Storage *p);
+
+/*
+** End of interface to code in fts5_storage.c.
+**************************************************************************/
+
+
+/**************************************************************************
+** Interface to code in fts5_expr.c. 
+*/
+typedef struct Fts5Expr Fts5Expr;
+typedef struct Fts5ExprNode Fts5ExprNode;
+typedef struct Fts5Parse Fts5Parse;
+typedef struct Fts5Token Fts5Token;
+typedef struct Fts5ExprPhrase Fts5ExprPhrase;
+typedef struct Fts5ExprNearset Fts5ExprNearset;
+
+struct Fts5Token {
+  const char *p;                  /* Token text (not NULL terminated) */
+  int n;                          /* Size of buffer p in bytes */
+};
+
+/* Parse a MATCH expression. */
+static int sqlite3Fts5ExprNew(
+  Fts5Config *pConfig, 
+  const char *zExpr,
+  Fts5Expr **ppNew, 
+  char **pzErr
+);
+
+/*
+** for(rc = sqlite3Fts5ExprFirst(pExpr, pIdx, bDesc);
+**     rc==SQLITE_OK && 0==sqlite3Fts5ExprEof(pExpr);
+**     rc = sqlite3Fts5ExprNext(pExpr)
+** ){
+**   // The document with rowid iRowid matches the expression!
+**   i64 iRowid = sqlite3Fts5ExprRowid(pExpr);
+** }
+*/
+static int sqlite3Fts5ExprFirst(Fts5Expr*, Fts5Index *pIdx, i64 iMin, int bDesc);
+static int sqlite3Fts5ExprNext(Fts5Expr*, i64 iMax);
+static int sqlite3Fts5ExprEof(Fts5Expr*);
+static i64 sqlite3Fts5ExprRowid(Fts5Expr*);
+
+static void sqlite3Fts5ExprFree(Fts5Expr*);
+
+/* Called during startup to register a UDF with SQLite */
+static int sqlite3Fts5ExprInit(Fts5Global*, sqlite3*);
+
+static int sqlite3Fts5ExprPhraseCount(Fts5Expr*);
+static int sqlite3Fts5ExprPhraseSize(Fts5Expr*, int iPhrase);
+static int sqlite3Fts5ExprPoslist(Fts5Expr*, int, const u8 **);
+
+typedef struct Fts5PoslistPopulator Fts5PoslistPopulator;
+static Fts5PoslistPopulator *sqlite3Fts5ExprClearPoslists(Fts5Expr*, int);
+static int sqlite3Fts5ExprPopulatePoslists(
+    Fts5Config*, Fts5Expr*, Fts5PoslistPopulator*, int, const char*, int
+);
+static void sqlite3Fts5ExprCheckPoslists(Fts5Expr*, i64);
+
+static int sqlite3Fts5ExprClonePhrase(Fts5Expr*, int, Fts5Expr**);
+
+static int sqlite3Fts5ExprPhraseCollist(Fts5Expr *, int, const u8 **, int *);
+
+/*******************************************
+** The fts5_expr.c API above this point is used by the other hand-written
+** C code in this module. The interfaces below this point are called by
+** the parser code in fts5parse.y.  */
+
+static void sqlite3Fts5ParseError(Fts5Parse *pParse, const char *zFmt, ...);
+
+static Fts5ExprNode *sqlite3Fts5ParseNode(
+  Fts5Parse *pParse,
+  int eType,
+  Fts5ExprNode *pLeft,
+  Fts5ExprNode *pRight,
+  Fts5ExprNearset *pNear
+);
+
+static Fts5ExprNode *sqlite3Fts5ParseImplicitAnd(
+  Fts5Parse *pParse,
+  Fts5ExprNode *pLeft,
+  Fts5ExprNode *pRight
+);
+
+static Fts5ExprPhrase *sqlite3Fts5ParseTerm(
+  Fts5Parse *pParse, 
+  Fts5ExprPhrase *pPhrase, 
+  Fts5Token *pToken,
+  int bPrefix
+);
+
+static Fts5ExprNearset *sqlite3Fts5ParseNearset(
+  Fts5Parse*, 
+  Fts5ExprNearset*,
+  Fts5ExprPhrase* 
+);
+
+static Fts5Colset *sqlite3Fts5ParseColset(
+  Fts5Parse*, 
+  Fts5Colset*, 
+  Fts5Token *
+);
+
+static void sqlite3Fts5ParsePhraseFree(Fts5ExprPhrase*);
+static void sqlite3Fts5ParseNearsetFree(Fts5ExprNearset*);
+static void sqlite3Fts5ParseNodeFree(Fts5ExprNode*);
+
+static void sqlite3Fts5ParseSetDistance(Fts5Parse*, Fts5ExprNearset*, Fts5Token*);
+static void sqlite3Fts5ParseSetColset(Fts5Parse*, Fts5ExprNearset*, Fts5Colset*);
+static Fts5Colset *sqlite3Fts5ParseColsetInvert(Fts5Parse*, Fts5Colset*);
+static void sqlite3Fts5ParseFinished(Fts5Parse *pParse, Fts5ExprNode *p);
+static void sqlite3Fts5ParseNear(Fts5Parse *pParse, Fts5Token*);
+
+/*
+** End of interface to code in fts5_expr.c.
+**************************************************************************/
+
+
+
+/**************************************************************************
+** Interface to code in fts5_aux.c. 
+*/
+
+static int sqlite3Fts5AuxInit(fts5_api*);
+/*
+** End of interface to code in fts5_aux.c.
+**************************************************************************/
+
+/**************************************************************************
+** Interface to code in fts5_tokenizer.c. 
+*/
+
+static int sqlite3Fts5TokenizerInit(fts5_api*);
+/*
+** End of interface to code in fts5_tokenizer.c.
+**************************************************************************/
+
+/**************************************************************************
+** Interface to code in fts5_vocab.c. 
+*/
+
+static int sqlite3Fts5VocabInit(Fts5Global*, sqlite3*);
+
+/*
+** End of interface to code in fts5_vocab.c.
+**************************************************************************/
+
+
+/**************************************************************************
+** Interface to automatically generated code in fts5_unicode2.c. 
+*/
+static int sqlite3Fts5UnicodeIsalnum(int c);
+static int sqlite3Fts5UnicodeIsdiacritic(int c);
+static int sqlite3Fts5UnicodeFold(int c, int bRemoveDiacritic);
+/*
+** End of interface to code in fts5_unicode2.c.
+**************************************************************************/
+
+#endif
+
+#define FTS5_OR                               1
+#define FTS5_AND                              2
+#define FTS5_NOT                              3
+#define FTS5_TERM                             4
+#define FTS5_COLON                            5
+#define FTS5_LP                               6
+#define FTS5_RP                               7
+#define FTS5_MINUS                            8
+#define FTS5_LCP                              9
+#define FTS5_RCP                             10
+#define FTS5_STRING                          11
+#define FTS5_COMMA                           12
+#define FTS5_PLUS                            13
+#define FTS5_STAR                            14
+
+/*
+** 2000-05-29
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** Driver template for the LEMON parser generator.
+**
+** The "lemon" program processes an LALR(1) input grammar file, then uses
+** this template to construct a parser.  The "lemon" program inserts text
+** at each "%%" line.  Also, any "P-a-r-s-e" identifer prefix (without the
+** interstitial "-" characters) contained in this template is changed into
+** the value of the %name directive from the grammar.  Otherwise, the content
+** of this template is copied straight through into the generate parser
+** source file.
+**
+** The following is the concatenation of all %include directives from the
+** input grammar file:
+*/
+/* #include <stdio.h> */
+/************ Begin %include sections from the grammar ************************/
+
+/* #include "fts5Int.h" */
+/* #include "fts5parse.h" */
+
+/*
+** Disable all error recovery processing in the parser push-down
+** automaton.
+*/
+#define fts5YYNOERRORRECOVERY 1
+
+/*
+** Make fts5yytestcase() the same as testcase()
+*/
+#define fts5yytestcase(X) testcase(X)
+
+/*
+** Indicate that sqlite3ParserFree() will never be called with a null
+** pointer.
+*/
+#define fts5YYPARSEFREENOTNULL 1
+
+/*
+** Alternative datatype for the argument to the malloc() routine passed
+** into sqlite3ParserAlloc().  The default is size_t.
+*/
+#define fts5YYMALLOCARGTYPE  u64
+
+/**************** End of %include directives **********************************/
+/* These constants specify the various numeric values for terminal symbols
+** in a format understandable to "makeheaders".  This section is blank unless
+** "lemon" is run with the "-m" command-line option.
+***************** Begin makeheaders token definitions *************************/
+/**************** End makeheaders token definitions ***************************/
+
+/* The next sections is a series of control #defines.
+** various aspects of the generated parser.
+**    fts5YYCODETYPE         is the data type used to store the integer codes
+**                       that represent terminal and non-terminal symbols.
+**                       "unsigned char" is used if there are fewer than
+**                       256 symbols.  Larger types otherwise.
+**    fts5YYNOCODE           is a number of type fts5YYCODETYPE that is not used for
+**                       any terminal or nonterminal symbol.
+**    fts5YYFALLBACK         If defined, this indicates that one or more tokens
+**                       (also known as: "terminal symbols") have fall-back
+**                       values which should be used if the original symbol
+**                       would not parse.  This permits keywords to sometimes
+**                       be used as identifiers, for example.
+**    fts5YYACTIONTYPE       is the data type used for "action codes" - numbers
+**                       that indicate what to do in response to the next
+**                       token.
+**    sqlite3Fts5ParserFTS5TOKENTYPE     is the data type used for minor type for terminal
+**                       symbols.  Background: A "minor type" is a semantic
+**                       value associated with a terminal or non-terminal
+**                       symbols.  For example, for an "ID" terminal symbol,
+**                       the minor type might be the name of the identifier.
+**                       Each non-terminal can have a different minor type.
+**                       Terminal symbols all have the same minor type, though.
+**                       This macros defines the minor type for terminal 
+**                       symbols.
+**    fts5YYMINORTYPE        is the data type used for all minor types.
+**                       This is typically a union of many types, one of
+**                       which is sqlite3Fts5ParserFTS5TOKENTYPE.  The entry in the union
+**                       for terminal symbols is called "fts5yy0".
+**    fts5YYSTACKDEPTH       is the maximum depth of the parser's stack.  If
+**                       zero the stack is dynamically sized using realloc()
+**    sqlite3Fts5ParserARG_SDECL     A static variable declaration for the %extra_argument
+**    sqlite3Fts5ParserARG_PDECL     A parameter declaration for the %extra_argument
+**    sqlite3Fts5ParserARG_STORE     Code to store %extra_argument into fts5yypParser
+**    sqlite3Fts5ParserARG_FETCH     Code to extract %extra_argument from fts5yypParser
+**    fts5YYERRORSYMBOL      is the code number of the error symbol.  If not
+**                       defined, then do no error processing.
+**    fts5YYNSTATE           the combined number of states.
+**    fts5YYNRULE            the number of rules in the grammar
+**    fts5YY_MAX_SHIFT       Maximum value for shift actions
+**    fts5YY_MIN_SHIFTREDUCE Minimum value for shift-reduce actions
+**    fts5YY_MAX_SHIFTREDUCE Maximum value for shift-reduce actions
+**    fts5YY_MIN_REDUCE      Maximum value for reduce actions
+**    fts5YY_ERROR_ACTION    The fts5yy_action[] code for syntax error
+**    fts5YY_ACCEPT_ACTION   The fts5yy_action[] code for accept
+**    fts5YY_NO_ACTION       The fts5yy_action[] code for no-op
+*/
+#ifndef INTERFACE
+# define INTERFACE 1
+#endif
+/************* Begin control #defines *****************************************/
+#define fts5YYCODETYPE unsigned char
+#define fts5YYNOCODE 28
+#define fts5YYACTIONTYPE unsigned char
+#define sqlite3Fts5ParserFTS5TOKENTYPE Fts5Token
+typedef union {
+  int fts5yyinit;
+  sqlite3Fts5ParserFTS5TOKENTYPE fts5yy0;
+  int fts5yy4;
+  Fts5Colset* fts5yy11;
+  Fts5ExprNode* fts5yy24;
+  Fts5ExprNearset* fts5yy46;
+  Fts5ExprPhrase* fts5yy53;
+} fts5YYMINORTYPE;
+#ifndef fts5YYSTACKDEPTH
+#define fts5YYSTACKDEPTH 100
+#endif
+#define sqlite3Fts5ParserARG_SDECL Fts5Parse *pParse;
+#define sqlite3Fts5ParserARG_PDECL ,Fts5Parse *pParse
+#define sqlite3Fts5ParserARG_FETCH Fts5Parse *pParse = fts5yypParser->pParse
+#define sqlite3Fts5ParserARG_STORE fts5yypParser->pParse = pParse
+#define fts5YYNSTATE             29
+#define fts5YYNRULE              26
+#define fts5YY_MAX_SHIFT         28
+#define fts5YY_MIN_SHIFTREDUCE   45
+#define fts5YY_MAX_SHIFTREDUCE   70
+#define fts5YY_MIN_REDUCE        71
+#define fts5YY_MAX_REDUCE        96
+#define fts5YY_ERROR_ACTION      97
+#define fts5YY_ACCEPT_ACTION     98
+#define fts5YY_NO_ACTION         99
+/************* End control #defines *******************************************/
+
+/* Define the fts5yytestcase() macro to be a no-op if is not already defined
+** otherwise.
+**
+** Applications can choose to define fts5yytestcase() in the %include section
+** to a macro that can assist in verifying code coverage.  For production
+** code the fts5yytestcase() macro should be turned off.  But it is useful
+** for testing.
+*/
+#ifndef fts5yytestcase
+# define fts5yytestcase(X)
+#endif
+
+
+/* Next are the tables used to determine what action to take based on the
+** current state and lookahead token.  These tables are used to implement
+** functions that take a state number and lookahead value and return an
+** action integer.  
+**
+** Suppose the action integer is N.  Then the action is determined as
+** follows
+**
+**   0 <= N <= fts5YY_MAX_SHIFT             Shift N.  That is, push the lookahead
+**                                      token onto the stack and goto state N.
+**
+**   N between fts5YY_MIN_SHIFTREDUCE       Shift to an arbitrary state then
+**     and fts5YY_MAX_SHIFTREDUCE           reduce by rule N-fts5YY_MIN_SHIFTREDUCE.
+**
+**   N between fts5YY_MIN_REDUCE            Reduce by rule N-fts5YY_MIN_REDUCE
+**     and fts5YY_MAX_REDUCE
+**
+**   N == fts5YY_ERROR_ACTION               A syntax error has occurred.
+**
+**   N == fts5YY_ACCEPT_ACTION              The parser accepts its input.
+**
+**   N == fts5YY_NO_ACTION                  No such action.  Denotes unused
+**                                      slots in the fts5yy_action[] table.
+**
+** The action table is constructed as a single large table named fts5yy_action[].
+** Given state S and lookahead X, the action is computed as either:
+**
+**    (A)   N = fts5yy_action[ fts5yy_shift_ofst[S] + X ]
+**    (B)   N = fts5yy_default[S]
+**
+** The (A) formula is preferred.  The B formula is used instead if:
+**    (1)  The fts5yy_shift_ofst[S]+X value is out of range, or
+**    (2)  fts5yy_lookahead[fts5yy_shift_ofst[S]+X] is not equal to X, or
+**    (3)  fts5yy_shift_ofst[S] equal fts5YY_SHIFT_USE_DFLT.
+** (Implementation note: fts5YY_SHIFT_USE_DFLT is chosen so that
+** fts5YY_SHIFT_USE_DFLT+X will be out of range for all possible lookaheads X.
+** Hence only tests (1) and (2) need to be evaluated.)
+**
+** The formulas above are for computing the action when the lookahead is
+** a terminal symbol.  If the lookahead is a non-terminal (as occurs after
+** a reduce action) then the fts5yy_reduce_ofst[] array is used in place of
+** the fts5yy_shift_ofst[] array and fts5YY_REDUCE_USE_DFLT is used in place of
+** fts5YY_SHIFT_USE_DFLT.
+**
+** The following are the tables generated in this section:
+**
+**  fts5yy_action[]        A single table containing all actions.
+**  fts5yy_lookahead[]     A table containing the lookahead for each entry in
+**                     fts5yy_action.  Used to detect hash collisions.
+**  fts5yy_shift_ofst[]    For each state, the offset into fts5yy_action for
+**                     shifting terminals.
+**  fts5yy_reduce_ofst[]   For each state, the offset into fts5yy_action for
+**                     shifting non-terminals after a reduce.
+**  fts5yy_default[]       Default action for each state.
+**
+*********** Begin parsing tables **********************************************/
+#define fts5YY_ACTTAB_COUNT (85)
+static const fts5YYACTIONTYPE fts5yy_action[] = {
+ /*     0 */    98,   16,   51,    5,   53,   27,   83,    7,   26,   15,
+ /*    10 */    51,    5,   53,   27,   13,   69,   26,   48,   51,    5,
+ /*    20 */    53,   27,   19,   11,   26,    9,   20,   51,    5,   53,
+ /*    30 */    27,   13,   22,   26,   28,   51,    5,   53,   27,   68,
+ /*    40 */     1,   26,   19,   11,   17,    9,   52,   10,   53,   27,
+ /*    50 */    23,   24,   26,   54,    3,    4,    2,   26,    6,   21,
+ /*    60 */    49,   71,    3,    4,    2,    7,   56,   59,   55,   59,
+ /*    70 */     4,    2,   12,   69,   58,   60,   18,   67,   62,   69,
+ /*    80 */    25,   66,    8,   14,    2,
+};
+static const fts5YYCODETYPE fts5yy_lookahead[] = {
+ /*     0 */    16,   17,   18,   19,   20,   21,    5,    6,   24,   17,
+ /*    10 */    18,   19,   20,   21,   11,   14,   24,   17,   18,   19,
+ /*    20 */    20,   21,    8,    9,   24,   11,   17,   18,   19,   20,
+ /*    30 */    21,   11,   12,   24,   17,   18,   19,   20,   21,   26,
+ /*    40 */     6,   24,    8,    9,   22,   11,   18,   11,   20,   21,
+ /*    50 */    24,   25,   24,   20,    1,    2,    3,   24,   23,   24,
+ /*    60 */     7,    0,    1,    2,    3,    6,   10,   11,   10,   11,
+ /*    70 */     2,    3,    9,   14,   11,   11,   22,   26,    7,   14,
+ /*    80 */    13,   11,    5,   11,    3,
+};
+#define fts5YY_SHIFT_USE_DFLT (85)
+#define fts5YY_SHIFT_COUNT    (28)
+#define fts5YY_SHIFT_MIN      (0)
+#define fts5YY_SHIFT_MAX      (81)
+static const unsigned char fts5yy_shift_ofst[] = {
+ /*     0 */    34,   34,   34,   34,   34,   14,   20,    3,   36,    1,
+ /*    10 */    59,   64,   64,   65,   65,   53,   61,   56,   58,   63,
+ /*    20 */    68,   67,   70,   67,   71,   72,   67,   77,   81,
+};
+#define fts5YY_REDUCE_USE_DFLT (-17)
+#define fts5YY_REDUCE_COUNT (14)
+#define fts5YY_REDUCE_MIN   (-16)
+#define fts5YY_REDUCE_MAX   (54)
+static const signed char fts5yy_reduce_ofst[] = {
+ /*     0 */   -16,   -8,    0,    9,   17,   28,   26,   35,   33,   13,
+ /*    10 */    13,   22,   54,   13,   51,
+};
+static const fts5YYACTIONTYPE fts5yy_default[] = {
+ /*     0 */    97,   97,   97,   97,   97,   76,   91,   97,   97,   96,
+ /*    10 */    96,   97,   97,   96,   96,   97,   97,   97,   97,   97,
+ /*    20 */    73,   89,   97,   90,   97,   97,   87,   97,   72,
+};
+/********** End of lemon-generated parsing tables *****************************/
+
+/* The next table maps tokens (terminal symbols) into fallback tokens.  
+** If a construct like the following:
+** 
+**      %fallback ID X Y Z.
+**
+** appears in the grammar, then ID becomes a fallback token for X, Y,
+** and Z.  Whenever one of the tokens X, Y, or Z is input to the parser
+** but it does not parse, the type of the token is changed to ID and
+** the parse is retried before an error is thrown.
+**
+** This feature can be used, for example, to cause some keywords in a language
+** to revert to identifiers if they keyword does not apply in the context where
+** it appears.
+*/
+#ifdef fts5YYFALLBACK
+static const fts5YYCODETYPE fts5yyFallback[] = {
+};
+#endif /* fts5YYFALLBACK */
+
+/* The following structure represents a single element of the
+** parser's stack.  Information stored includes:
+**
+**   +  The state number for the parser at this level of the stack.
+**
+**   +  The value of the token stored at this level of the stack.
+**      (In other words, the "major" token.)
+**
+**   +  The semantic value stored at this level of the stack.  This is
+**      the information used by the action routines in the grammar.
+**      It is sometimes called the "minor" token.
+**
+** After the "shift" half of a SHIFTREDUCE action, the stateno field
+** actually contains the reduce action for the second half of the
+** SHIFTREDUCE.
+*/
+struct fts5yyStackEntry {
+  fts5YYACTIONTYPE stateno;  /* The state-number, or reduce action in SHIFTREDUCE */
+  fts5YYCODETYPE major;      /* The major token value.  This is the code
+                         ** number for the token at this stack level */
+  fts5YYMINORTYPE minor;     /* The user-supplied minor token value.  This
+                         ** is the value of the token  */
+};
+typedef struct fts5yyStackEntry fts5yyStackEntry;
+
+/* The state of the parser is completely contained in an instance of
+** the following structure */
+struct fts5yyParser {
+  fts5yyStackEntry *fts5yytos;          /* Pointer to top element of the stack */
+#ifdef fts5YYTRACKMAXSTACKDEPTH
+  int fts5yyhwm;                    /* High-water mark of the stack */
+#endif
+#ifndef fts5YYNOERRORRECOVERY
+  int fts5yyerrcnt;                 /* Shifts left before out of the error */
+#endif
+  sqlite3Fts5ParserARG_SDECL                /* A place to hold %extra_argument */
+#if fts5YYSTACKDEPTH<=0
+  int fts5yystksz;                  /* Current side of the stack */
+  fts5yyStackEntry *fts5yystack;        /* The parser's stack */
+  fts5yyStackEntry fts5yystk0;          /* First stack entry */
+#else
+  fts5yyStackEntry fts5yystack[fts5YYSTACKDEPTH];  /* The parser's stack */
+#endif
+};
+typedef struct fts5yyParser fts5yyParser;
+
+#ifndef NDEBUG
+/* #include <stdio.h> */
+static FILE *fts5yyTraceFILE = 0;
+static char *fts5yyTracePrompt = 0;
+#endif /* NDEBUG */
+
+#ifndef NDEBUG
+/* 
+** Turn parser tracing on by giving a stream to which to write the trace
+** and a prompt to preface each trace message.  Tracing is turned off
+** by making either argument NULL 
+**
+** Inputs:
+** <ul>
+** <li> A FILE* to which trace output should be written.
+**      If NULL, then tracing is turned off.
+** <li> A prefix string written at the beginning of every
+**      line of trace output.  If NULL, then tracing is
+**      turned off.
+** </ul>
+**
+** Outputs:
+** None.
+*/
+static void sqlite3Fts5ParserTrace(FILE *TraceFILE, char *zTracePrompt){
+  fts5yyTraceFILE = TraceFILE;
+  fts5yyTracePrompt = zTracePrompt;
+  if( fts5yyTraceFILE==0 ) fts5yyTracePrompt = 0;
+  else if( fts5yyTracePrompt==0 ) fts5yyTraceFILE = 0;
+}
+#endif /* NDEBUG */
+
+#ifndef NDEBUG
+/* For tracing shifts, the names of all terminals and nonterminals
+** are required.  The following table supplies these names */
+static const char *const fts5yyTokenName[] = { 
+  "$",             "OR",            "AND",           "NOT",         
+  "TERM",          "COLON",         "LP",            "RP",          
+  "MINUS",         "LCP",           "RCP",           "STRING",      
+  "COMMA",         "PLUS",          "STAR",          "error",       
+  "input",         "expr",          "cnearset",      "exprlist",    
+  "nearset",       "colset",        "colsetlist",    "nearphrases", 
+  "phrase",        "neardist_opt",  "star_opt",    
+};
+#endif /* NDEBUG */
+
+#ifndef NDEBUG
+/* For tracing reduce actions, the names of all rules are required.
+*/
+static const char *const fts5yyRuleName[] = {
+ /*   0 */ "input ::= expr",
+ /*   1 */ "expr ::= expr AND expr",
+ /*   2 */ "expr ::= expr OR expr",
+ /*   3 */ "expr ::= expr NOT expr",
+ /*   4 */ "expr ::= LP expr RP",
+ /*   5 */ "expr ::= exprlist",
+ /*   6 */ "exprlist ::= cnearset",
+ /*   7 */ "exprlist ::= exprlist cnearset",
+ /*   8 */ "cnearset ::= nearset",
+ /*   9 */ "cnearset ::= colset COLON nearset",
+ /*  10 */ "colset ::= MINUS LCP colsetlist RCP",
+ /*  11 */ "colset ::= LCP colsetlist RCP",
+ /*  12 */ "colset ::= STRING",
+ /*  13 */ "colset ::= MINUS STRING",
+ /*  14 */ "colsetlist ::= colsetlist STRING",
+ /*  15 */ "colsetlist ::= STRING",
+ /*  16 */ "nearset ::= phrase",
+ /*  17 */ "nearset ::= STRING LP nearphrases neardist_opt RP",
+ /*  18 */ "nearphrases ::= phrase",
+ /*  19 */ "nearphrases ::= nearphrases phrase",
+ /*  20 */ "neardist_opt ::=",
+ /*  21 */ "neardist_opt ::= COMMA STRING",
+ /*  22 */ "phrase ::= phrase PLUS STRING star_opt",
+ /*  23 */ "phrase ::= STRING star_opt",
+ /*  24 */ "star_opt ::= STAR",
+ /*  25 */ "star_opt ::=",
+};
+#endif /* NDEBUG */
+
+
+#if fts5YYSTACKDEPTH<=0
+/*
+** Try to increase the size of the parser stack.  Return the number
+** of errors.  Return 0 on success.
+*/
+static int fts5yyGrowStack(fts5yyParser *p){
+  int newSize;
+  int idx;
+  fts5yyStackEntry *pNew;
+
+  newSize = p->fts5yystksz*2 + 100;
+  idx = p->fts5yytos ? (int)(p->fts5yytos - p->fts5yystack) : 0;
+  if( p->fts5yystack==&p->fts5yystk0 ){
+    pNew = malloc(newSize*sizeof(pNew[0]));
+    if( pNew ) pNew[0] = p->fts5yystk0;
+  }else{
+    pNew = realloc(p->fts5yystack, newSize*sizeof(pNew[0]));
+  }
+  if( pNew ){
+    p->fts5yystack = pNew;
+    p->fts5yytos = &p->fts5yystack[idx];
+#ifndef NDEBUG
+    if( fts5yyTraceFILE ){
+      fprintf(fts5yyTraceFILE,"%sStack grows from %d to %d entries.\n",
+              fts5yyTracePrompt, p->fts5yystksz, newSize);
+    }
+#endif
+    p->fts5yystksz = newSize;
+  }
+  return pNew==0; 
+}
+#endif
+
+/* Datatype of the argument to the memory allocated passed as the
+** second argument to sqlite3Fts5ParserAlloc() below.  This can be changed by
+** putting an appropriate #define in the %include section of the input
+** grammar.
+*/
+#ifndef fts5YYMALLOCARGTYPE
+# define fts5YYMALLOCARGTYPE size_t
+#endif
+
+/* 
+** This function allocates a new parser.
+** The only argument is a pointer to a function which works like
+** malloc.
+**
+** Inputs:
+** A pointer to the function used to allocate memory.
+**
+** Outputs:
+** A pointer to a parser.  This pointer is used in subsequent calls
+** to sqlite3Fts5Parser and sqlite3Fts5ParserFree.
+*/
+static void *sqlite3Fts5ParserAlloc(void *(*mallocProc)(fts5YYMALLOCARGTYPE)){
+  fts5yyParser *pParser;
+  pParser = (fts5yyParser*)(*mallocProc)( (fts5YYMALLOCARGTYPE)sizeof(fts5yyParser) );
+  if( pParser ){
+#ifdef fts5YYTRACKMAXSTACKDEPTH
+    pParser->fts5yyhwm = 0;
+#endif
+#if fts5YYSTACKDEPTH<=0
+    pParser->fts5yytos = NULL;
+    pParser->fts5yystack = NULL;
+    pParser->fts5yystksz = 0;
+    if( fts5yyGrowStack(pParser) ){
+      pParser->fts5yystack = &pParser->fts5yystk0;
+      pParser->fts5yystksz = 1;
+    }
+#endif
+#ifndef fts5YYNOERRORRECOVERY
+    pParser->fts5yyerrcnt = -1;
+#endif
+    pParser->fts5yytos = pParser->fts5yystack;
+    pParser->fts5yystack[0].stateno = 0;
+    pParser->fts5yystack[0].major = 0;
+  }
+  return pParser;
+}
+
+/* The following function deletes the "minor type" or semantic value
+** associated with a symbol.  The symbol can be either a terminal
+** or nonterminal. "fts5yymajor" is the symbol code, and "fts5yypminor" is
+** a pointer to the value to be deleted.  The code used to do the 
+** deletions is derived from the %destructor and/or %token_destructor
+** directives of the input grammar.
+*/
+static void fts5yy_destructor(
+  fts5yyParser *fts5yypParser,    /* The parser */
+  fts5YYCODETYPE fts5yymajor,     /* Type code for object to destroy */
+  fts5YYMINORTYPE *fts5yypminor   /* The object to be destroyed */
+){
+  sqlite3Fts5ParserARG_FETCH;
+  switch( fts5yymajor ){
+    /* Here is inserted the actions which take place when a
+    ** terminal or non-terminal is destroyed.  This can happen
+    ** when the symbol is popped from the stack during a
+    ** reduce or during error processing or when a parser is 
+    ** being destroyed before it is finished parsing.
+    **
+    ** Note: during a reduce, the only symbols destroyed are those
+    ** which appear on the RHS of the rule, but which are *not* used
+    ** inside the C code.
+    */
+/********* Begin destructor definitions ***************************************/
+    case 16: /* input */
+{
+ (void)pParse; 
+}
+      break;
+    case 17: /* expr */
+    case 18: /* cnearset */
+    case 19: /* exprlist */
+{
+ sqlite3Fts5ParseNodeFree((fts5yypminor->fts5yy24)); 
+}
+      break;
+    case 20: /* nearset */
+    case 23: /* nearphrases */
+{
+ sqlite3Fts5ParseNearsetFree((fts5yypminor->fts5yy46)); 
+}
+      break;
+    case 21: /* colset */
+    case 22: /* colsetlist */
+{
+ sqlite3_free((fts5yypminor->fts5yy11)); 
+}
+      break;
+    case 24: /* phrase */
+{
+ sqlite3Fts5ParsePhraseFree((fts5yypminor->fts5yy53)); 
+}
+      break;
+/********* End destructor definitions *****************************************/
+    default:  break;   /* If no destructor action specified: do nothing */
+  }
+}
+
+/*
+** Pop the parser's stack once.
+**
+** If there is a destructor routine associated with the token which
+** is popped from the stack, then call it.
+*/
+static void fts5yy_pop_parser_stack(fts5yyParser *pParser){
+  fts5yyStackEntry *fts5yytos;
+  assert( pParser->fts5yytos!=0 );
+  assert( pParser->fts5yytos > pParser->fts5yystack );
+  fts5yytos = pParser->fts5yytos--;
+#ifndef NDEBUG
+  if( fts5yyTraceFILE ){
+    fprintf(fts5yyTraceFILE,"%sPopping %s\n",
+      fts5yyTracePrompt,
+      fts5yyTokenName[fts5yytos->major]);
+  }
+#endif
+  fts5yy_destructor(pParser, fts5yytos->major, &fts5yytos->minor);
+}
+
+/* 
+** Deallocate and destroy a parser.  Destructors are called for
+** all stack elements before shutting the parser down.
+**
+** If the fts5YYPARSEFREENEVERNULL macro exists (for example because it
+** is defined in a %include section of the input grammar) then it is
+** assumed that the input pointer is never NULL.
+*/
+static void sqlite3Fts5ParserFree(
+  void *p,                    /* The parser to be deleted */
+  void (*freeProc)(void*)     /* Function used to reclaim memory */
+){
+  fts5yyParser *pParser = (fts5yyParser*)p;
+#ifndef fts5YYPARSEFREENEVERNULL
+  if( pParser==0 ) return;
+#endif
+  while( pParser->fts5yytos>pParser->fts5yystack ) fts5yy_pop_parser_stack(pParser);
+#if fts5YYSTACKDEPTH<=0
+  if( pParser->fts5yystack!=&pParser->fts5yystk0 ) free(pParser->fts5yystack);
+#endif
+  (*freeProc)((void*)pParser);
+}
+
+/*
+** Return the peak depth of the stack for a parser.
+*/
+#ifdef fts5YYTRACKMAXSTACKDEPTH
+static int sqlite3Fts5ParserStackPeak(void *p){
+  fts5yyParser *pParser = (fts5yyParser*)p;
+  return pParser->fts5yyhwm;
+}
+#endif
+
+/*
+** Find the appropriate action for a parser given the terminal
+** look-ahead token iLookAhead.
+*/
+static unsigned int fts5yy_find_shift_action(
+  fts5yyParser *pParser,        /* The parser */
+  fts5YYCODETYPE iLookAhead     /* The look-ahead token */
+){
+  int i;
+  int stateno = pParser->fts5yytos->stateno;
+ 
+  if( stateno>=fts5YY_MIN_REDUCE ) return stateno;
+  assert( stateno <= fts5YY_SHIFT_COUNT );
+  do{
+    i = fts5yy_shift_ofst[stateno];
+    assert( iLookAhead!=fts5YYNOCODE );
+    i += iLookAhead;
+    if( i<0 || i>=fts5YY_ACTTAB_COUNT || fts5yy_lookahead[i]!=iLookAhead ){
+#ifdef fts5YYFALLBACK
+      fts5YYCODETYPE iFallback;            /* Fallback token */
+      if( iLookAhead<sizeof(fts5yyFallback)/sizeof(fts5yyFallback[0])
+             && (iFallback = fts5yyFallback[iLookAhead])!=0 ){
+#ifndef NDEBUG
+        if( fts5yyTraceFILE ){
+          fprintf(fts5yyTraceFILE, "%sFALLBACK %s => %s\n",
+             fts5yyTracePrompt, fts5yyTokenName[iLookAhead], fts5yyTokenName[iFallback]);
+        }
+#endif
+        assert( fts5yyFallback[iFallback]==0 ); /* Fallback loop must terminate */
+        iLookAhead = iFallback;
+        continue;
+      }
+#endif
+#ifdef fts5YYWILDCARD
+      {
+        int j = i - iLookAhead + fts5YYWILDCARD;
+        if( 
+#if fts5YY_SHIFT_MIN+fts5YYWILDCARD<0
+          j>=0 &&
+#endif
+#if fts5YY_SHIFT_MAX+fts5YYWILDCARD>=fts5YY_ACTTAB_COUNT
+          j<fts5YY_ACTTAB_COUNT &&
+#endif
+          fts5yy_lookahead[j]==fts5YYWILDCARD && iLookAhead>0
+        ){
+#ifndef NDEBUG
+          if( fts5yyTraceFILE ){
+            fprintf(fts5yyTraceFILE, "%sWILDCARD %s => %s\n",
+               fts5yyTracePrompt, fts5yyTokenName[iLookAhead],
+               fts5yyTokenName[fts5YYWILDCARD]);
+          }
+#endif /* NDEBUG */
+          return fts5yy_action[j];
+        }
+      }
+#endif /* fts5YYWILDCARD */
+      return fts5yy_default[stateno];
+    }else{
+      return fts5yy_action[i];
+    }
+  }while(1);
+}
+
+/*
+** Find the appropriate action for a parser given the non-terminal
+** look-ahead token iLookAhead.
+*/
+static int fts5yy_find_reduce_action(
+  int stateno,              /* Current state number */
+  fts5YYCODETYPE iLookAhead     /* The look-ahead token */
+){
+  int i;
+#ifdef fts5YYERRORSYMBOL
+  if( stateno>fts5YY_REDUCE_COUNT ){
+    return fts5yy_default[stateno];
+  }
+#else
+  assert( stateno<=fts5YY_REDUCE_COUNT );
+#endif
+  i = fts5yy_reduce_ofst[stateno];
+  assert( i!=fts5YY_REDUCE_USE_DFLT );
+  assert( iLookAhead!=fts5YYNOCODE );
+  i += iLookAhead;
+#ifdef fts5YYERRORSYMBOL
+  if( i<0 || i>=fts5YY_ACTTAB_COUNT || fts5yy_lookahead[i]!=iLookAhead ){
+    return fts5yy_default[stateno];
+  }
+#else
+  assert( i>=0 && i<fts5YY_ACTTAB_COUNT );
+  assert( fts5yy_lookahead[i]==iLookAhead );
+#endif
+  return fts5yy_action[i];
+}
+
+/*
+** The following routine is called if the stack overflows.
+*/
+static void fts5yyStackOverflow(fts5yyParser *fts5yypParser){
+   sqlite3Fts5ParserARG_FETCH;
+   fts5yypParser->fts5yytos--;
+#ifndef NDEBUG
+   if( fts5yyTraceFILE ){
+     fprintf(fts5yyTraceFILE,"%sStack Overflow!\n",fts5yyTracePrompt);
+   }
+#endif
+   while( fts5yypParser->fts5yytos>fts5yypParser->fts5yystack ) fts5yy_pop_parser_stack(fts5yypParser);
+   /* Here code is inserted which will execute if the parser
+   ** stack every overflows */
+/******** Begin %stack_overflow code ******************************************/
+
+  sqlite3Fts5ParseError(pParse, "fts5: parser stack overflow");
+/******** End %stack_overflow code ********************************************/
+   sqlite3Fts5ParserARG_STORE; /* Suppress warning about unused %extra_argument var */
+}
+
+/*
+** Print tracing information for a SHIFT action
+*/
+#ifndef NDEBUG
+static void fts5yyTraceShift(fts5yyParser *fts5yypParser, int fts5yyNewState){
+  if( fts5yyTraceFILE ){
+    if( fts5yyNewState<fts5YYNSTATE ){
+      fprintf(fts5yyTraceFILE,"%sShift '%s', go to state %d\n",
+         fts5yyTracePrompt,fts5yyTokenName[fts5yypParser->fts5yytos->major],
+         fts5yyNewState);
+    }else{
+      fprintf(fts5yyTraceFILE,"%sShift '%s'\n",
+         fts5yyTracePrompt,fts5yyTokenName[fts5yypParser->fts5yytos->major]);
+    }
+  }
+}
+#else
+# define fts5yyTraceShift(X,Y)
+#endif
+
+/*
+** Perform a shift action.
+*/
+static void fts5yy_shift(
+  fts5yyParser *fts5yypParser,          /* The parser to be shifted */
+  int fts5yyNewState,               /* The new state to shift in */
+  int fts5yyMajor,                  /* The major token to shift in */
+  sqlite3Fts5ParserFTS5TOKENTYPE fts5yyMinor        /* The minor token to shift in */
+){
+  fts5yyStackEntry *fts5yytos;
+  fts5yypParser->fts5yytos++;
+#ifdef fts5YYTRACKMAXSTACKDEPTH
+  if( (int)(fts5yypParser->fts5yytos - fts5yypParser->fts5yystack)>fts5yypParser->fts5yyhwm ){
+    fts5yypParser->fts5yyhwm++;
+    assert( fts5yypParser->fts5yyhwm == (int)(fts5yypParser->fts5yytos - fts5yypParser->fts5yystack) );
+  }
+#endif
+#if fts5YYSTACKDEPTH>0 
+  if( fts5yypParser->fts5yytos>=&fts5yypParser->fts5yystack[fts5YYSTACKDEPTH] ){
+    fts5yyStackOverflow(fts5yypParser);
+    return;
+  }
+#else
+  if( fts5yypParser->fts5yytos>=&fts5yypParser->fts5yystack[fts5yypParser->fts5yystksz] ){
+    if( fts5yyGrowStack(fts5yypParser) ){
+      fts5yyStackOverflow(fts5yypParser);
+      return;
+    }
+  }
+#endif
+  if( fts5yyNewState > fts5YY_MAX_SHIFT ){
+    fts5yyNewState += fts5YY_MIN_REDUCE - fts5YY_MIN_SHIFTREDUCE;
+  }
+  fts5yytos = fts5yypParser->fts5yytos;
+  fts5yytos->stateno = (fts5YYACTIONTYPE)fts5yyNewState;
+  fts5yytos->major = (fts5YYCODETYPE)fts5yyMajor;
+  fts5yytos->minor.fts5yy0 = fts5yyMinor;
+  fts5yyTraceShift(fts5yypParser, fts5yyNewState);
+}
+
+/* The following table contains information about every rule that
+** is used during the reduce.
+*/
+static const struct {
+  fts5YYCODETYPE lhs;         /* Symbol on the left-hand side of the rule */
+  unsigned char nrhs;     /* Number of right-hand side symbols in the rule */
+} fts5yyRuleInfo[] = {
+  { 16, 1 },
+  { 17, 3 },
+  { 17, 3 },
+  { 17, 3 },
+  { 17, 3 },
+  { 17, 1 },
+  { 19, 1 },
+  { 19, 2 },
+  { 18, 1 },
+  { 18, 3 },
+  { 21, 4 },
+  { 21, 3 },
+  { 21, 1 },
+  { 21, 2 },
+  { 22, 2 },
+  { 22, 1 },
+  { 20, 1 },
+  { 20, 5 },
+  { 23, 1 },
+  { 23, 2 },
+  { 25, 0 },
+  { 25, 2 },
+  { 24, 4 },
+  { 24, 2 },
+  { 26, 1 },
+  { 26, 0 },
+};
+
+static void fts5yy_accept(fts5yyParser*);  /* Forward Declaration */
+
+/*
+** Perform a reduce action and the shift that must immediately
+** follow the reduce.
+*/
+static void fts5yy_reduce(
+  fts5yyParser *fts5yypParser,         /* The parser */
+  unsigned int fts5yyruleno        /* Number of the rule by which to reduce */
+){
+  int fts5yygoto;                     /* The next state */
+  int fts5yyact;                      /* The next action */
+  fts5yyStackEntry *fts5yymsp;            /* The top of the parser's stack */
+  int fts5yysize;                     /* Amount to pop the stack */
+  sqlite3Fts5ParserARG_FETCH;
+  fts5yymsp = fts5yypParser->fts5yytos;
+#ifndef NDEBUG
+  if( fts5yyTraceFILE && fts5yyruleno<(int)(sizeof(fts5yyRuleName)/sizeof(fts5yyRuleName[0])) ){
+    fts5yysize = fts5yyRuleInfo[fts5yyruleno].nrhs;
+    fprintf(fts5yyTraceFILE, "%sReduce [%s], go to state %d.\n", fts5yyTracePrompt,
+      fts5yyRuleName[fts5yyruleno], fts5yymsp[-fts5yysize].stateno);
+  }
+#endif /* NDEBUG */
+
+  /* Check that the stack is large enough to grow by a single entry
+  ** if the RHS of the rule is empty.  This ensures that there is room
+  ** enough on the stack to push the LHS value */
+  if( fts5yyRuleInfo[fts5yyruleno].nrhs==0 ){
+#ifdef fts5YYTRACKMAXSTACKDEPTH
+    if( (int)(fts5yypParser->fts5yytos - fts5yypParser->fts5yystack)>fts5yypParser->fts5yyhwm ){
+      fts5yypParser->fts5yyhwm++;
+      assert( fts5yypParser->fts5yyhwm == (int)(fts5yypParser->fts5yytos - fts5yypParser->fts5yystack));
+    }
+#endif
+#if fts5YYSTACKDEPTH>0 
+    if( fts5yypParser->fts5yytos>=&fts5yypParser->fts5yystack[fts5YYSTACKDEPTH-1] ){
+      fts5yyStackOverflow(fts5yypParser);
+      return;
+    }
+#else
+    if( fts5yypParser->fts5yytos>=&fts5yypParser->fts5yystack[fts5yypParser->fts5yystksz-1] ){
+      if( fts5yyGrowStack(fts5yypParser) ){
+        fts5yyStackOverflow(fts5yypParser);
+        return;
+      }
+      fts5yymsp = fts5yypParser->fts5yytos;
+    }
+#endif
+  }
+
+  switch( fts5yyruleno ){
+  /* Beginning here are the reduction cases.  A typical example
+  ** follows:
+  **   case 0:
+  **  #line <lineno> <grammarfile>
+  **     { ... }           // User supplied code
+  **  #line <lineno> <thisfile>
+  **     break;
+  */
+/********** Begin reduce actions **********************************************/
+        fts5YYMINORTYPE fts5yylhsminor;
+      case 0: /* input ::= expr */
+{ sqlite3Fts5ParseFinished(pParse, fts5yymsp[0].minor.fts5yy24); }
+        break;
+      case 1: /* expr ::= expr AND expr */
+{
+  fts5yylhsminor.fts5yy24 = sqlite3Fts5ParseNode(pParse, FTS5_AND, fts5yymsp[-2].minor.fts5yy24, fts5yymsp[0].minor.fts5yy24, 0);
+}
+  fts5yymsp[-2].minor.fts5yy24 = fts5yylhsminor.fts5yy24;
+        break;
+      case 2: /* expr ::= expr OR expr */
+{
+  fts5yylhsminor.fts5yy24 = sqlite3Fts5ParseNode(pParse, FTS5_OR, fts5yymsp[-2].minor.fts5yy24, fts5yymsp[0].minor.fts5yy24, 0);
+}
+  fts5yymsp[-2].minor.fts5yy24 = fts5yylhsminor.fts5yy24;
+        break;
+      case 3: /* expr ::= expr NOT expr */
+{
+  fts5yylhsminor.fts5yy24 = sqlite3Fts5ParseNode(pParse, FTS5_NOT, fts5yymsp[-2].minor.fts5yy24, fts5yymsp[0].minor.fts5yy24, 0);
+}
+  fts5yymsp[-2].minor.fts5yy24 = fts5yylhsminor.fts5yy24;
+        break;
+      case 4: /* expr ::= LP expr RP */
+{fts5yymsp[-2].minor.fts5yy24 = fts5yymsp[-1].minor.fts5yy24;}
+        break;
+      case 5: /* expr ::= exprlist */
+      case 6: /* exprlist ::= cnearset */ fts5yytestcase(fts5yyruleno==6);
+{fts5yylhsminor.fts5yy24 = fts5yymsp[0].minor.fts5yy24;}
+  fts5yymsp[0].minor.fts5yy24 = fts5yylhsminor.fts5yy24;
+        break;
+      case 7: /* exprlist ::= exprlist cnearset */
+{
+  fts5yylhsminor.fts5yy24 = sqlite3Fts5ParseImplicitAnd(pParse, fts5yymsp[-1].minor.fts5yy24, fts5yymsp[0].minor.fts5yy24);
+}
+  fts5yymsp[-1].minor.fts5yy24 = fts5yylhsminor.fts5yy24;
+        break;
+      case 8: /* cnearset ::= nearset */
+{ 
+  fts5yylhsminor.fts5yy24 = sqlite3Fts5ParseNode(pParse, FTS5_STRING, 0, 0, fts5yymsp[0].minor.fts5yy46); 
+}
+  fts5yymsp[0].minor.fts5yy24 = fts5yylhsminor.fts5yy24;
+        break;
+      case 9: /* cnearset ::= colset COLON nearset */
+{ 
+  sqlite3Fts5ParseSetColset(pParse, fts5yymsp[0].minor.fts5yy46, fts5yymsp[-2].minor.fts5yy11);
+  fts5yylhsminor.fts5yy24 = sqlite3Fts5ParseNode(pParse, FTS5_STRING, 0, 0, fts5yymsp[0].minor.fts5yy46); 
+}
+  fts5yymsp[-2].minor.fts5yy24 = fts5yylhsminor.fts5yy24;
+        break;
+      case 10: /* colset ::= MINUS LCP colsetlist RCP */
+{ 
+    fts5yymsp[-3].minor.fts5yy11 = sqlite3Fts5ParseColsetInvert(pParse, fts5yymsp[-1].minor.fts5yy11);
+}
+        break;
+      case 11: /* colset ::= LCP colsetlist RCP */
+{ fts5yymsp[-2].minor.fts5yy11 = fts5yymsp[-1].minor.fts5yy11; }
+        break;
+      case 12: /* colset ::= STRING */
+{
+  fts5yylhsminor.fts5yy11 = sqlite3Fts5ParseColset(pParse, 0, &fts5yymsp[0].minor.fts5yy0);
+}
+  fts5yymsp[0].minor.fts5yy11 = fts5yylhsminor.fts5yy11;
+        break;
+      case 13: /* colset ::= MINUS STRING */
+{
+  fts5yymsp[-1].minor.fts5yy11 = sqlite3Fts5ParseColset(pParse, 0, &fts5yymsp[0].minor.fts5yy0);
+  fts5yymsp[-1].minor.fts5yy11 = sqlite3Fts5ParseColsetInvert(pParse, fts5yymsp[-1].minor.fts5yy11);
+}
+        break;
+      case 14: /* colsetlist ::= colsetlist STRING */
+{ 
+  fts5yylhsminor.fts5yy11 = sqlite3Fts5ParseColset(pParse, fts5yymsp[-1].minor.fts5yy11, &fts5yymsp[0].minor.fts5yy0); }
+  fts5yymsp[-1].minor.fts5yy11 = fts5yylhsminor.fts5yy11;
+        break;
+      case 15: /* colsetlist ::= STRING */
+{ 
+  fts5yylhsminor.fts5yy11 = sqlite3Fts5ParseColset(pParse, 0, &fts5yymsp[0].minor.fts5yy0); 
+}
+  fts5yymsp[0].minor.fts5yy11 = fts5yylhsminor.fts5yy11;
+        break;
+      case 16: /* nearset ::= phrase */
+{ fts5yylhsminor.fts5yy46 = sqlite3Fts5ParseNearset(pParse, 0, fts5yymsp[0].minor.fts5yy53); }
+  fts5yymsp[0].minor.fts5yy46 = fts5yylhsminor.fts5yy46;
+        break;
+      case 17: /* nearset ::= STRING LP nearphrases neardist_opt RP */
+{
+  sqlite3Fts5ParseNear(pParse, &fts5yymsp[-4].minor.fts5yy0);
+  sqlite3Fts5ParseSetDistance(pParse, fts5yymsp[-2].minor.fts5yy46, &fts5yymsp[-1].minor.fts5yy0);
+  fts5yylhsminor.fts5yy46 = fts5yymsp[-2].minor.fts5yy46;
+}
+  fts5yymsp[-4].minor.fts5yy46 = fts5yylhsminor.fts5yy46;
+        break;
+      case 18: /* nearphrases ::= phrase */
+{ 
+  fts5yylhsminor.fts5yy46 = sqlite3Fts5ParseNearset(pParse, 0, fts5yymsp[0].minor.fts5yy53); 
+}
+  fts5yymsp[0].minor.fts5yy46 = fts5yylhsminor.fts5yy46;
+        break;
+      case 19: /* nearphrases ::= nearphrases phrase */
+{
+  fts5yylhsminor.fts5yy46 = sqlite3Fts5ParseNearset(pParse, fts5yymsp[-1].minor.fts5yy46, fts5yymsp[0].minor.fts5yy53);
+}
+  fts5yymsp[-1].minor.fts5yy46 = fts5yylhsminor.fts5yy46;
+        break;
+      case 20: /* neardist_opt ::= */
+{ fts5yymsp[1].minor.fts5yy0.p = 0; fts5yymsp[1].minor.fts5yy0.n = 0; }
+        break;
+      case 21: /* neardist_opt ::= COMMA STRING */
+{ fts5yymsp[-1].minor.fts5yy0 = fts5yymsp[0].minor.fts5yy0; }
+        break;
+      case 22: /* phrase ::= phrase PLUS STRING star_opt */
+{ 
+  fts5yylhsminor.fts5yy53 = sqlite3Fts5ParseTerm(pParse, fts5yymsp[-3].minor.fts5yy53, &fts5yymsp[-1].minor.fts5yy0, fts5yymsp[0].minor.fts5yy4);
+}
+  fts5yymsp[-3].minor.fts5yy53 = fts5yylhsminor.fts5yy53;
+        break;
+      case 23: /* phrase ::= STRING star_opt */
+{ 
+  fts5yylhsminor.fts5yy53 = sqlite3Fts5ParseTerm(pParse, 0, &fts5yymsp[-1].minor.fts5yy0, fts5yymsp[0].minor.fts5yy4);
+}
+  fts5yymsp[-1].minor.fts5yy53 = fts5yylhsminor.fts5yy53;
+        break;
+      case 24: /* star_opt ::= STAR */
+{ fts5yymsp[0].minor.fts5yy4 = 1; }
+        break;
+      case 25: /* star_opt ::= */
+{ fts5yymsp[1].minor.fts5yy4 = 0; }
+        break;
+      default:
+        break;
+/********** End reduce actions ************************************************/
+  };
+  assert( fts5yyruleno<sizeof(fts5yyRuleInfo)/sizeof(fts5yyRuleInfo[0]) );
+  fts5yygoto = fts5yyRuleInfo[fts5yyruleno].lhs;
+  fts5yysize = fts5yyRuleInfo[fts5yyruleno].nrhs;
+  fts5yyact = fts5yy_find_reduce_action(fts5yymsp[-fts5yysize].stateno,(fts5YYCODETYPE)fts5yygoto);
+  if( fts5yyact <= fts5YY_MAX_SHIFTREDUCE ){
+    if( fts5yyact>fts5YY_MAX_SHIFT ){
+      fts5yyact += fts5YY_MIN_REDUCE - fts5YY_MIN_SHIFTREDUCE;
+    }
+    fts5yymsp -= fts5yysize-1;
+    fts5yypParser->fts5yytos = fts5yymsp;
+    fts5yymsp->stateno = (fts5YYACTIONTYPE)fts5yyact;
+    fts5yymsp->major = (fts5YYCODETYPE)fts5yygoto;
+    fts5yyTraceShift(fts5yypParser, fts5yyact);
+  }else{
+    assert( fts5yyact == fts5YY_ACCEPT_ACTION );
+    fts5yypParser->fts5yytos -= fts5yysize;
+    fts5yy_accept(fts5yypParser);
+  }
+}
+
+/*
+** The following code executes when the parse fails
+*/
+#ifndef fts5YYNOERRORRECOVERY
+static void fts5yy_parse_failed(
+  fts5yyParser *fts5yypParser           /* The parser */
+){
+  sqlite3Fts5ParserARG_FETCH;
+#ifndef NDEBUG
+  if( fts5yyTraceFILE ){
+    fprintf(fts5yyTraceFILE,"%sFail!\n",fts5yyTracePrompt);
+  }
+#endif
+  while( fts5yypParser->fts5yytos>fts5yypParser->fts5yystack ) fts5yy_pop_parser_stack(fts5yypParser);
+  /* Here code is inserted which will be executed whenever the
+  ** parser fails */
+/************ Begin %parse_failure code ***************************************/
+/************ End %parse_failure code *****************************************/
+  sqlite3Fts5ParserARG_STORE; /* Suppress warning about unused %extra_argument variable */
+}
+#endif /* fts5YYNOERRORRECOVERY */
+
+/*
+** The following code executes when a syntax error first occurs.
+*/
+static void fts5yy_syntax_error(
+  fts5yyParser *fts5yypParser,           /* The parser */
+  int fts5yymajor,                   /* The major type of the error token */
+  sqlite3Fts5ParserFTS5TOKENTYPE fts5yyminor         /* The minor type of the error token */
+){
+  sqlite3Fts5ParserARG_FETCH;
+#define FTS5TOKEN fts5yyminor
+/************ Begin %syntax_error code ****************************************/
+
+  UNUSED_PARAM(fts5yymajor); /* Silence a compiler warning */
+  sqlite3Fts5ParseError(
+    pParse, "fts5: syntax error near \"%.*s\"",FTS5TOKEN.n,FTS5TOKEN.p
+  );
+/************ End %syntax_error code ******************************************/
+  sqlite3Fts5ParserARG_STORE; /* Suppress warning about unused %extra_argument variable */
+}
+
+/*
+** The following is executed when the parser accepts
+*/
+static void fts5yy_accept(
+  fts5yyParser *fts5yypParser           /* The parser */
+){
+  sqlite3Fts5ParserARG_FETCH;
+#ifndef NDEBUG
+  if( fts5yyTraceFILE ){
+    fprintf(fts5yyTraceFILE,"%sAccept!\n",fts5yyTracePrompt);
+  }
+#endif
+#ifndef fts5YYNOERRORRECOVERY
+  fts5yypParser->fts5yyerrcnt = -1;
+#endif
+  assert( fts5yypParser->fts5yytos==fts5yypParser->fts5yystack );
+  /* Here code is inserted which will be executed whenever the
+  ** parser accepts */
+/*********** Begin %parse_accept code *****************************************/
+/*********** End %parse_accept code *******************************************/
+  sqlite3Fts5ParserARG_STORE; /* Suppress warning about unused %extra_argument variable */
+}
+
+/* The main parser program.
+** The first argument is a pointer to a structure obtained from
+** "sqlite3Fts5ParserAlloc" which describes the current state of the parser.
+** The second argument is the major token number.  The third is
+** the minor token.  The fourth optional argument is whatever the
+** user wants (and specified in the grammar) and is available for
+** use by the action routines.
+**
+** Inputs:
+** <ul>
+** <li> A pointer to the parser (an opaque structure.)
+** <li> The major token number.
+** <li> The minor token number.
+** <li> An option argument of a grammar-specified type.
+** </ul>
+**
+** Outputs:
+** None.
+*/
+static void sqlite3Fts5Parser(
+  void *fts5yyp,                   /* The parser */
+  int fts5yymajor,                 /* The major token code number */
+  sqlite3Fts5ParserFTS5TOKENTYPE fts5yyminor       /* The value for the token */
+  sqlite3Fts5ParserARG_PDECL               /* Optional %extra_argument parameter */
+){
+  fts5YYMINORTYPE fts5yyminorunion;
+  unsigned int fts5yyact;   /* The parser action. */
+#if !defined(fts5YYERRORSYMBOL) && !defined(fts5YYNOERRORRECOVERY)
+  int fts5yyendofinput;     /* True if we are at the end of input */
+#endif
+#ifdef fts5YYERRORSYMBOL
+  int fts5yyerrorhit = 0;   /* True if fts5yymajor has invoked an error */
+#endif
+  fts5yyParser *fts5yypParser;  /* The parser */
+
+  fts5yypParser = (fts5yyParser*)fts5yyp;
+  assert( fts5yypParser->fts5yytos!=0 );
+#if !defined(fts5YYERRORSYMBOL) && !defined(fts5YYNOERRORRECOVERY)
+  fts5yyendofinput = (fts5yymajor==0);
+#endif
+  sqlite3Fts5ParserARG_STORE;
+
+#ifndef NDEBUG
+  if( fts5yyTraceFILE ){
+    fprintf(fts5yyTraceFILE,"%sInput '%s'\n",fts5yyTracePrompt,fts5yyTokenName[fts5yymajor]);
+  }
+#endif
+
+  do{
+    fts5yyact = fts5yy_find_shift_action(fts5yypParser,(fts5YYCODETYPE)fts5yymajor);
+    if( fts5yyact <= fts5YY_MAX_SHIFTREDUCE ){
+      fts5yy_shift(fts5yypParser,fts5yyact,fts5yymajor,fts5yyminor);
+#ifndef fts5YYNOERRORRECOVERY
+      fts5yypParser->fts5yyerrcnt--;
+#endif
+      fts5yymajor = fts5YYNOCODE;
+    }else if( fts5yyact <= fts5YY_MAX_REDUCE ){
+      fts5yy_reduce(fts5yypParser,fts5yyact-fts5YY_MIN_REDUCE);
+    }else{
+      assert( fts5yyact == fts5YY_ERROR_ACTION );
+      fts5yyminorunion.fts5yy0 = fts5yyminor;
+#ifdef fts5YYERRORSYMBOL
+      int fts5yymx;
+#endif
+#ifndef NDEBUG
+      if( fts5yyTraceFILE ){
+        fprintf(fts5yyTraceFILE,"%sSyntax Error!\n",fts5yyTracePrompt);
+      }
+#endif
+#ifdef fts5YYERRORSYMBOL
+      /* A syntax error has occurred.
+      ** The response to an error depends upon whether or not the
+      ** grammar defines an error token "ERROR".  
+      **
+      ** This is what we do if the grammar does define ERROR:
+      **
+      **  * Call the %syntax_error function.
+      **
+      **  * Begin popping the stack until we enter a state where
+      **    it is legal to shift the error symbol, then shift
+      **    the error symbol.
+      **
+      **  * Set the error count to three.
+      **
+      **  * Begin accepting and shifting new tokens.  No new error
+      **    processing will occur until three tokens have been
+      **    shifted successfully.
+      **
+      */
+      if( fts5yypParser->fts5yyerrcnt<0 ){
+        fts5yy_syntax_error(fts5yypParser,fts5yymajor,fts5yyminor);
+      }
+      fts5yymx = fts5yypParser->fts5yytos->major;
+      if( fts5yymx==fts5YYERRORSYMBOL || fts5yyerrorhit ){
+#ifndef NDEBUG
+        if( fts5yyTraceFILE ){
+          fprintf(fts5yyTraceFILE,"%sDiscard input token %s\n",
+             fts5yyTracePrompt,fts5yyTokenName[fts5yymajor]);
+        }
+#endif
+        fts5yy_destructor(fts5yypParser, (fts5YYCODETYPE)fts5yymajor, &fts5yyminorunion);
+        fts5yymajor = fts5YYNOCODE;
+      }else{
+        while( fts5yypParser->fts5yytos >= fts5yypParser->fts5yystack
+            && fts5yymx != fts5YYERRORSYMBOL
+            && (fts5yyact = fts5yy_find_reduce_action(
+                        fts5yypParser->fts5yytos->stateno,
+                        fts5YYERRORSYMBOL)) >= fts5YY_MIN_REDUCE
+        ){
+          fts5yy_pop_parser_stack(fts5yypParser);
+        }
+        if( fts5yypParser->fts5yytos < fts5yypParser->fts5yystack || fts5yymajor==0 ){
+          fts5yy_destructor(fts5yypParser,(fts5YYCODETYPE)fts5yymajor,&fts5yyminorunion);
+          fts5yy_parse_failed(fts5yypParser);
+#ifndef fts5YYNOERRORRECOVERY
+          fts5yypParser->fts5yyerrcnt = -1;
+#endif
+          fts5yymajor = fts5YYNOCODE;
+        }else if( fts5yymx!=fts5YYERRORSYMBOL ){
+          fts5yy_shift(fts5yypParser,fts5yyact,fts5YYERRORSYMBOL,fts5yyminor);
+        }
+      }
+      fts5yypParser->fts5yyerrcnt = 3;
+      fts5yyerrorhit = 1;
+#elif defined(fts5YYNOERRORRECOVERY)
+      /* If the fts5YYNOERRORRECOVERY macro is defined, then do not attempt to
+      ** do any kind of error recovery.  Instead, simply invoke the syntax
+      ** error routine and continue going as if nothing had happened.
+      **
+      ** Applications can set this macro (for example inside %include) if
+      ** they intend to abandon the parse upon the first syntax error seen.
+      */
+      fts5yy_syntax_error(fts5yypParser,fts5yymajor, fts5yyminor);
+      fts5yy_destructor(fts5yypParser,(fts5YYCODETYPE)fts5yymajor,&fts5yyminorunion);
+      fts5yymajor = fts5YYNOCODE;
+      
+#else  /* fts5YYERRORSYMBOL is not defined */
+      /* This is what we do if the grammar does not define ERROR:
+      **
+      **  * Report an error message, and throw away the input token.
+      **
+      **  * If the input token is $, then fail the parse.
+      **
+      ** As before, subsequent error messages are suppressed until
+      ** three input tokens have been successfully shifted.
+      */
+      if( fts5yypParser->fts5yyerrcnt<=0 ){
+        fts5yy_syntax_error(fts5yypParser,fts5yymajor, fts5yyminor);
+      }
+      fts5yypParser->fts5yyerrcnt = 3;
+      fts5yy_destructor(fts5yypParser,(fts5YYCODETYPE)fts5yymajor,&fts5yyminorunion);
+      if( fts5yyendofinput ){
+        fts5yy_parse_failed(fts5yypParser);
+#ifndef fts5YYNOERRORRECOVERY
+        fts5yypParser->fts5yyerrcnt = -1;
+#endif
+      }
+      fts5yymajor = fts5YYNOCODE;
+#endif
+    }
+  }while( fts5yymajor!=fts5YYNOCODE && fts5yypParser->fts5yytos>fts5yypParser->fts5yystack );
+#ifndef NDEBUG
+  if( fts5yyTraceFILE ){
+    fts5yyStackEntry *i;
+    char cDiv = '[';
+    fprintf(fts5yyTraceFILE,"%sReturn. Stack=",fts5yyTracePrompt);
+    for(i=&fts5yypParser->fts5yystack[1]; i<=fts5yypParser->fts5yytos; i++){
+      fprintf(fts5yyTraceFILE,"%c%s", cDiv, fts5yyTokenName[i->major]);
+      cDiv = ' ';
+    }
+    fprintf(fts5yyTraceFILE,"]\n");
+  }
+#endif
+  return;
+}
+
+/*
+** 2014 May 31
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+*/
+
+
+/* #include "fts5Int.h" */
+#include <math.h>                 /* amalgamator: keep */
+
+/*
+** Object used to iterate through all "coalesced phrase instances" in 
+** a single column of the current row. If the phrase instances in the
+** column being considered do not overlap, this object simply iterates
+** through them. Or, if they do overlap (share one or more tokens in
+** common), each set of overlapping instances is treated as a single
+** match. See documentation for the highlight() auxiliary function for
+** details.
+**
+** Usage is:
+**
+**   for(rc = fts5CInstIterNext(pApi, pFts, iCol, &iter);
+**      (rc==SQLITE_OK && 0==fts5CInstIterEof(&iter);
+**      rc = fts5CInstIterNext(&iter)
+**   ){
+**     printf("instance starts at %d, ends at %d\n", iter.iStart, iter.iEnd);
+**   }
+**
+*/
+typedef struct CInstIter CInstIter;
+struct CInstIter {
+  const Fts5ExtensionApi *pApi;   /* API offered by current FTS version */
+  Fts5Context *pFts;              /* First arg to pass to pApi functions */
+  int iCol;                       /* Column to search */
+  int iInst;                      /* Next phrase instance index */
+  int nInst;                      /* Total number of phrase instances */
+
+  /* Output variables */
+  int iStart;                     /* First token in coalesced phrase instance */
+  int iEnd;                       /* Last token in coalesced phrase instance */
+};
+
+/*
+** Advance the iterator to the next coalesced phrase instance. Return
+** an SQLite error code if an error occurs, or SQLITE_OK otherwise.
+*/
+static int fts5CInstIterNext(CInstIter *pIter){
+  int rc = SQLITE_OK;
+  pIter->iStart = -1;
+  pIter->iEnd = -1;
+
+  while( rc==SQLITE_OK && pIter->iInst<pIter->nInst ){
+    int ip; int ic; int io;
+    rc = pIter->pApi->xInst(pIter->pFts, pIter->iInst, &ip, &ic, &io);
+    if( rc==SQLITE_OK ){
+      if( ic==pIter->iCol ){
+        int iEnd = io - 1 + pIter->pApi->xPhraseSize(pIter->pFts, ip);
+        if( pIter->iStart<0 ){
+          pIter->iStart = io;
+          pIter->iEnd = iEnd;
+        }else if( io<=pIter->iEnd ){
+          if( iEnd>pIter->iEnd ) pIter->iEnd = iEnd;
+        }else{
+          break;
+        }
+      }
+      pIter->iInst++;
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Initialize the iterator object indicated by the final parameter to 
+** iterate through coalesced phrase instances in column iCol.
+*/
+static int fts5CInstIterInit(
+  const Fts5ExtensionApi *pApi,
+  Fts5Context *pFts,
+  int iCol,
+  CInstIter *pIter
+){
+  int rc;
+
+  memset(pIter, 0, sizeof(CInstIter));
+  pIter->pApi = pApi;
+  pIter->pFts = pFts;
+  pIter->iCol = iCol;
+  rc = pApi->xInstCount(pFts, &pIter->nInst);
+
+  if( rc==SQLITE_OK ){
+    rc = fts5CInstIterNext(pIter);
+  }
+
+  return rc;
+}
+
+
+
+/*************************************************************************
+** Start of highlight() implementation.
+*/
+typedef struct HighlightContext HighlightContext;
+struct HighlightContext {
+  CInstIter iter;                 /* Coalesced Instance Iterator */
+  int iPos;                       /* Current token offset in zIn[] */
+  int iRangeStart;                /* First token to include */
+  int iRangeEnd;                  /* If non-zero, last token to include */
+  const char *zOpen;              /* Opening highlight */
+  const char *zClose;             /* Closing highlight */
+  const char *zIn;                /* Input text */
+  int nIn;                        /* Size of input text in bytes */
+  int iOff;                       /* Current offset within zIn[] */
+  char *zOut;                     /* Output value */
+};
+
+/*
+** Append text to the HighlightContext output string - p->zOut. Argument
+** z points to a buffer containing n bytes of text to append. If n is 
+** negative, everything up until the first '\0' is appended to the output.
+**
+** If *pRc is set to any value other than SQLITE_OK when this function is 
+** called, it is a no-op. If an error (i.e. an OOM condition) is encountered, 
+** *pRc is set to an error code before returning. 
+*/
+static void fts5HighlightAppend(
+  int *pRc, 
+  HighlightContext *p, 
+  const char *z, int n
+){
+  if( *pRc==SQLITE_OK ){
+    if( n<0 ) n = (int)strlen(z);
+    p->zOut = sqlite3_mprintf("%z%.*s", p->zOut, n, z);
+    if( p->zOut==0 ) *pRc = SQLITE_NOMEM;
+  }
+}
+
+/*
+** Tokenizer callback used by implementation of highlight() function.
+*/
+static int fts5HighlightCb(
+  void *pContext,                 /* Pointer to HighlightContext object */
+  int tflags,                     /* Mask of FTS5_TOKEN_* flags */
+  const char *pToken,             /* Buffer containing token */
+  int nToken,                     /* Size of token in bytes */
+  int iStartOff,                  /* Start offset of token */
+  int iEndOff                     /* End offset of token */
+){
+  HighlightContext *p = (HighlightContext*)pContext;
+  int rc = SQLITE_OK;
+  int iPos;
+
+  UNUSED_PARAM2(pToken, nToken);
+
+  if( tflags & FTS5_TOKEN_COLOCATED ) return SQLITE_OK;
+  iPos = p->iPos++;
+
+  if( p->iRangeEnd>0 ){
+    if( iPos<p->iRangeStart || iPos>p->iRangeEnd ) return SQLITE_OK;
+    if( p->iRangeStart && iPos==p->iRangeStart ) p->iOff = iStartOff;
+  }
+
+  if( iPos==p->iter.iStart ){
+    fts5HighlightAppend(&rc, p, &p->zIn[p->iOff], iStartOff - p->iOff);
+    fts5HighlightAppend(&rc, p, p->zOpen, -1);
+    p->iOff = iStartOff;
+  }
+
+  if( iPos==p->iter.iEnd ){
+    if( p->iRangeEnd && p->iter.iStart<p->iRangeStart ){
+      fts5HighlightAppend(&rc, p, p->zOpen, -1);
+    }
+    fts5HighlightAppend(&rc, p, &p->zIn[p->iOff], iEndOff - p->iOff);
+    fts5HighlightAppend(&rc, p, p->zClose, -1);
+    p->iOff = iEndOff;
+    if( rc==SQLITE_OK ){
+      rc = fts5CInstIterNext(&p->iter);
+    }
+  }
+
+  if( p->iRangeEnd>0 && iPos==p->iRangeEnd ){
+    fts5HighlightAppend(&rc, p, &p->zIn[p->iOff], iEndOff - p->iOff);
+    p->iOff = iEndOff;
+    if( iPos>=p->iter.iStart && iPos<p->iter.iEnd ){
+      fts5HighlightAppend(&rc, p, p->zClose, -1);
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Implementation of highlight() function.
+*/
+static void fts5HighlightFunction(
+  const Fts5ExtensionApi *pApi,   /* API offered by current FTS version */
+  Fts5Context *pFts,              /* First arg to pass to pApi functions */
+  sqlite3_context *pCtx,          /* Context for returning result/error */
+  int nVal,                       /* Number of values in apVal[] array */
+  sqlite3_value **apVal           /* Array of trailing arguments */
+){
+  HighlightContext ctx;
+  int rc;
+  int iCol;
+
+  if( nVal!=3 ){
+    const char *zErr = "wrong number of arguments to function highlight()";
+    sqlite3_result_error(pCtx, zErr, -1);
+    return;
+  }
+
+  iCol = sqlite3_value_int(apVal[0]);
+  memset(&ctx, 0, sizeof(HighlightContext));
+  ctx.zOpen = (const char*)sqlite3_value_text(apVal[1]);
+  ctx.zClose = (const char*)sqlite3_value_text(apVal[2]);
+  rc = pApi->xColumnText(pFts, iCol, &ctx.zIn, &ctx.nIn);
+
+  if( ctx.zIn ){
+    if( rc==SQLITE_OK ){
+      rc = fts5CInstIterInit(pApi, pFts, iCol, &ctx.iter);
+    }
+
+    if( rc==SQLITE_OK ){
+      rc = pApi->xTokenize(pFts, ctx.zIn, ctx.nIn, (void*)&ctx,fts5HighlightCb);
+    }
+    fts5HighlightAppend(&rc, &ctx, &ctx.zIn[ctx.iOff], ctx.nIn - ctx.iOff);
+
+    if( rc==SQLITE_OK ){
+      sqlite3_result_text(pCtx, (const char*)ctx.zOut, -1, SQLITE_TRANSIENT);
+    }
+    sqlite3_free(ctx.zOut);
+  }
+  if( rc!=SQLITE_OK ){
+    sqlite3_result_error_code(pCtx, rc);
+  }
+}
+/*
+** End of highlight() implementation.
+**************************************************************************/
+
+/*
+** Context object passed to the fts5SentenceFinderCb() function.
+*/
+typedef struct Fts5SFinder Fts5SFinder;
+struct Fts5SFinder {
+  int iPos;                       /* Current token position */
+  int nFirstAlloc;                /* Allocated size of aFirst[] */
+  int nFirst;                     /* Number of entries in aFirst[] */
+  int *aFirst;                    /* Array of first token in each sentence */
+  const char *zDoc;               /* Document being tokenized */
+};
+
+/*
+** Add an entry to the Fts5SFinder.aFirst[] array. Grow the array if
+** necessary. Return SQLITE_OK if successful, or SQLITE_NOMEM if an
+** error occurs.
+*/
+static int fts5SentenceFinderAdd(Fts5SFinder *p, int iAdd){
+  if( p->nFirstAlloc==p->nFirst ){
+    int nNew = p->nFirstAlloc ? p->nFirstAlloc*2 : 64;
+    int *aNew;
+
+    aNew = (int*)sqlite3_realloc(p->aFirst, nNew*sizeof(int));
+    if( aNew==0 ) return SQLITE_NOMEM;
+    p->aFirst = aNew;
+    p->nFirstAlloc = nNew;
+  }
+  p->aFirst[p->nFirst++] = iAdd;
+  return SQLITE_OK;
+}
+
+/*
+** This function is an xTokenize() callback used by the auxiliary snippet()
+** function. Its job is to identify tokens that are the first in a sentence.
+** For each such token, an entry is added to the SFinder.aFirst[] array.
+*/
+static int fts5SentenceFinderCb(
+  void *pContext,                 /* Pointer to HighlightContext object */
+  int tflags,                     /* Mask of FTS5_TOKEN_* flags */
+  const char *pToken,             /* Buffer containing token */
+  int nToken,                     /* Size of token in bytes */
+  int iStartOff,                  /* Start offset of token */
+  int iEndOff                     /* End offset of token */
+){
+  int rc = SQLITE_OK;
+
+  UNUSED_PARAM2(pToken, nToken);
+  UNUSED_PARAM(iEndOff);
+
+  if( (tflags & FTS5_TOKEN_COLOCATED)==0 ){
+    Fts5SFinder *p = (Fts5SFinder*)pContext;
+    if( p->iPos>0 ){
+      int i;
+      char c = 0;
+      for(i=iStartOff-1; i>=0; i--){
+        c = p->zDoc[i];
+        if( c!=' ' && c!='\t' && c!='\n' && c!='\r' ) break;
+      }
+      if( i!=iStartOff-1 && (c=='.' || c==':') ){
+        rc = fts5SentenceFinderAdd(p, p->iPos);
+      }
+    }else{
+      rc = fts5SentenceFinderAdd(p, 0);
+    }
+    p->iPos++;
+  }
+  return rc;
+}
+
+static int fts5SnippetScore(
+  const Fts5ExtensionApi *pApi,   /* API offered by current FTS version */
+  Fts5Context *pFts,              /* First arg to pass to pApi functions */
+  int nDocsize,                   /* Size of column in tokens */
+  unsigned char *aSeen,           /* Array with one element per query phrase */
+  int iCol,                       /* Column to score */
+  int iPos,                       /* Starting offset to score */
+  int nToken,                     /* Max tokens per snippet */
+  int *pnScore,                   /* OUT: Score */
+  int *piPos                      /* OUT: Adjusted offset */
+){
+  int rc;
+  int i;
+  int ip = 0;
+  int ic = 0;
+  int iOff = 0;
+  int iFirst = -1;
+  int nInst;
+  int nScore = 0;
+  int iLast = 0;
+
+  rc = pApi->xInstCount(pFts, &nInst);
+  for(i=0; i<nInst && rc==SQLITE_OK; i++){
+    rc = pApi->xInst(pFts, i, &ip, &ic, &iOff);
+    if( rc==SQLITE_OK && ic==iCol && iOff>=iPos && iOff<(iPos+nToken) ){
+      nScore += (aSeen[ip] ? 1 : 1000);
+      aSeen[ip] = 1;
+      if( iFirst<0 ) iFirst = iOff;
+      iLast = iOff + pApi->xPhraseSize(pFts, ip);
+    }
+  }
+
+  *pnScore = nScore;
+  if( piPos ){
+    int iAdj = iFirst - (nToken - (iLast-iFirst)) / 2;
+    if( (iAdj+nToken)>nDocsize ) iAdj = nDocsize - nToken;
+    if( iAdj<0 ) iAdj = 0;
+    *piPos = iAdj;
+  }
+
+  return rc;
+}
+
+/*
+** Implementation of snippet() function.
+*/
+static void fts5SnippetFunction(
+  const Fts5ExtensionApi *pApi,   /* API offered by current FTS version */
+  Fts5Context *pFts,              /* First arg to pass to pApi functions */
+  sqlite3_context *pCtx,          /* Context for returning result/error */
+  int nVal,                       /* Number of values in apVal[] array */
+  sqlite3_value **apVal           /* Array of trailing arguments */
+){
+  HighlightContext ctx;
+  int rc = SQLITE_OK;             /* Return code */
+  int iCol;                       /* 1st argument to snippet() */
+  const char *zEllips;            /* 4th argument to snippet() */
+  int nToken;                     /* 5th argument to snippet() */
+  int nInst = 0;                  /* Number of instance matches this row */
+  int i;                          /* Used to iterate through instances */
+  int nPhrase;                    /* Number of phrases in query */
+  unsigned char *aSeen;           /* Array of "seen instance" flags */
+  int iBestCol;                   /* Column containing best snippet */
+  int iBestStart = 0;             /* First token of best snippet */
+  int nBestScore = 0;             /* Score of best snippet */
+  int nColSize = 0;               /* Total size of iBestCol in tokens */
+  Fts5SFinder sFinder;            /* Used to find the beginnings of sentences */
+  int nCol;
+
+  if( nVal!=5 ){
+    const char *zErr = "wrong number of arguments to function snippet()";
+    sqlite3_result_error(pCtx, zErr, -1);
+    return;
+  }
+
+  nCol = pApi->xColumnCount(pFts);
+  memset(&ctx, 0, sizeof(HighlightContext));
+  iCol = sqlite3_value_int(apVal[0]);
+  ctx.zOpen = (const char*)sqlite3_value_text(apVal[1]);
+  ctx.zClose = (const char*)sqlite3_value_text(apVal[2]);
+  zEllips = (const char*)sqlite3_value_text(apVal[3]);
+  nToken = sqlite3_value_int(apVal[4]);
+
+  iBestCol = (iCol>=0 ? iCol : 0);
+  nPhrase = pApi->xPhraseCount(pFts);
+  aSeen = sqlite3_malloc(nPhrase);
+  if( aSeen==0 ){
+    rc = SQLITE_NOMEM;
+  }
+  if( rc==SQLITE_OK ){
+    rc = pApi->xInstCount(pFts, &nInst);
+  }
+
+  memset(&sFinder, 0, sizeof(Fts5SFinder));
+  for(i=0; i<nCol; i++){
+    if( iCol<0 || iCol==i ){
+      int nDoc;
+      int nDocsize;
+      int ii;
+      sFinder.iPos = 0;
+      sFinder.nFirst = 0;
+      rc = pApi->xColumnText(pFts, i, &sFinder.zDoc, &nDoc);
+      if( rc!=SQLITE_OK ) break;
+      rc = pApi->xTokenize(pFts, 
+          sFinder.zDoc, nDoc, (void*)&sFinder,fts5SentenceFinderCb
+      );
+      if( rc!=SQLITE_OK ) break;
+      rc = pApi->xColumnSize(pFts, i, &nDocsize);
+      if( rc!=SQLITE_OK ) break;
+
+      for(ii=0; rc==SQLITE_OK && ii<nInst; ii++){
+        int ip, ic, io;
+        int iAdj;
+        int nScore;
+        int jj;
+
+        rc = pApi->xInst(pFts, ii, &ip, &ic, &io);
+        if( ic!=i || rc!=SQLITE_OK ) continue;
+        memset(aSeen, 0, nPhrase);
+        rc = fts5SnippetScore(pApi, pFts, nDocsize, aSeen, i,
+            io, nToken, &nScore, &iAdj
+        );
+        if( rc==SQLITE_OK && nScore>nBestScore ){
+          nBestScore = nScore;
+          iBestCol = i;
+          iBestStart = iAdj;
+          nColSize = nDocsize;
+        }
+
+        if( rc==SQLITE_OK && sFinder.nFirst && nDocsize>nToken ){
+          for(jj=0; jj<(sFinder.nFirst-1); jj++){
+            if( sFinder.aFirst[jj+1]>io ) break;
+          }
+
+          if( sFinder.aFirst[jj]<io ){
+            memset(aSeen, 0, nPhrase);
+            rc = fts5SnippetScore(pApi, pFts, nDocsize, aSeen, i, 
+              sFinder.aFirst[jj], nToken, &nScore, 0
+            );
+
+            nScore += (sFinder.aFirst[jj]==0 ? 120 : 100);
+            if( rc==SQLITE_OK && nScore>nBestScore ){
+              nBestScore = nScore;
+              iBestCol = i;
+              iBestStart = sFinder.aFirst[jj];
+              nColSize = nDocsize;
+            }
+          }
+        }
+      }
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = pApi->xColumnText(pFts, iBestCol, &ctx.zIn, &ctx.nIn);
+  }
+  if( rc==SQLITE_OK && nColSize==0 ){
+    rc = pApi->xColumnSize(pFts, iBestCol, &nColSize);
+  }
+  if( ctx.zIn ){
+    if( rc==SQLITE_OK ){
+      rc = fts5CInstIterInit(pApi, pFts, iBestCol, &ctx.iter);
+    }
+
+    ctx.iRangeStart = iBestStart;
+    ctx.iRangeEnd = iBestStart + nToken - 1;
+
+    if( iBestStart>0 ){
+      fts5HighlightAppend(&rc, &ctx, zEllips, -1);
+    }
+
+    /* Advance iterator ctx.iter so that it points to the first coalesced
+    ** phrase instance at or following position iBestStart. */
+    while( ctx.iter.iStart>=0 && ctx.iter.iStart<iBestStart && rc==SQLITE_OK ){
+      rc = fts5CInstIterNext(&ctx.iter);
+    }
+
+    if( rc==SQLITE_OK ){
+      rc = pApi->xTokenize(pFts, ctx.zIn, ctx.nIn, (void*)&ctx,fts5HighlightCb);
+    }
+    if( ctx.iRangeEnd>=(nColSize-1) ){
+      fts5HighlightAppend(&rc, &ctx, &ctx.zIn[ctx.iOff], ctx.nIn - ctx.iOff);
+    }else{
+      fts5HighlightAppend(&rc, &ctx, zEllips, -1);
+    }
+  }
+  if( rc==SQLITE_OK ){
+    sqlite3_result_text(pCtx, (const char*)ctx.zOut, -1, SQLITE_TRANSIENT);
+  }else{
+    sqlite3_result_error_code(pCtx, rc);
+  }
+  sqlite3_free(ctx.zOut);
+  sqlite3_free(aSeen);
+  sqlite3_free(sFinder.aFirst);
+}
+
+/************************************************************************/
+
+/*
+** The first time the bm25() function is called for a query, an instance
+** of the following structure is allocated and populated.
+*/
+typedef struct Fts5Bm25Data Fts5Bm25Data;
+struct Fts5Bm25Data {
+  int nPhrase;                    /* Number of phrases in query */
+  double avgdl;                   /* Average number of tokens in each row */
+  double *aIDF;                   /* IDF for each phrase */
+  double *aFreq;                  /* Array used to calculate phrase freq. */
+};
+
+/*
+** Callback used by fts5Bm25GetData() to count the number of rows in the
+** table matched by each individual phrase within the query.
+*/
+static int fts5CountCb(
+  const Fts5ExtensionApi *pApi, 
+  Fts5Context *pFts,
+  void *pUserData                 /* Pointer to sqlite3_int64 variable */
+){
+  sqlite3_int64 *pn = (sqlite3_int64*)pUserData;
+  UNUSED_PARAM2(pApi, pFts);
+  (*pn)++;
+  return SQLITE_OK;
+}
+
+/*
+** Set *ppData to point to the Fts5Bm25Data object for the current query. 
+** If the object has not already been allocated, allocate and populate it
+** now.
+*/
+static int fts5Bm25GetData(
+  const Fts5ExtensionApi *pApi, 
+  Fts5Context *pFts,
+  Fts5Bm25Data **ppData           /* OUT: bm25-data object for this query */
+){
+  int rc = SQLITE_OK;             /* Return code */
+  Fts5Bm25Data *p;                /* Object to return */
+
+  p = pApi->xGetAuxdata(pFts, 0);
+  if( p==0 ){
+    int nPhrase;                  /* Number of phrases in query */
+    sqlite3_int64 nRow = 0;       /* Number of rows in table */
+    sqlite3_int64 nToken = 0;     /* Number of tokens in table */
+    int nByte;                    /* Bytes of space to allocate */
+    int i;
+
+    /* Allocate the Fts5Bm25Data object */
+    nPhrase = pApi->xPhraseCount(pFts);
+    nByte = sizeof(Fts5Bm25Data) + nPhrase*2*sizeof(double);
+    p = (Fts5Bm25Data*)sqlite3_malloc(nByte);
+    if( p==0 ){
+      rc = SQLITE_NOMEM;
+    }else{
+      memset(p, 0, nByte);
+      p->nPhrase = nPhrase;
+      p->aIDF = (double*)&p[1];
+      p->aFreq = &p->aIDF[nPhrase];
+    }
+
+    /* Calculate the average document length for this FTS5 table */
+    if( rc==SQLITE_OK ) rc = pApi->xRowCount(pFts, &nRow);
+    if( rc==SQLITE_OK ) rc = pApi->xColumnTotalSize(pFts, -1, &nToken);
+    if( rc==SQLITE_OK ) p->avgdl = (double)nToken  / (double)nRow;
+
+    /* Calculate an IDF for each phrase in the query */
+    for(i=0; rc==SQLITE_OK && i<nPhrase; i++){
+      sqlite3_int64 nHit = 0;
+      rc = pApi->xQueryPhrase(pFts, i, (void*)&nHit, fts5CountCb);
+      if( rc==SQLITE_OK ){
+        /* Calculate the IDF (Inverse Document Frequency) for phrase i.
+        ** This is done using the standard BM25 formula as found on wikipedia:
+        **
+        **   IDF = log( (N - nHit + 0.5) / (nHit + 0.5) )
+        **
+        ** where "N" is the total number of documents in the set and nHit
+        ** is the number that contain at least one instance of the phrase
+        ** under consideration.
+        **
+        ** The problem with this is that if (N < 2*nHit), the IDF is 
+        ** negative. Which is undesirable. So the mimimum allowable IDF is
+        ** (1e-6) - roughly the same as a term that appears in just over
+        ** half of set of 5,000,000 documents.  */
+        double idf = log( (nRow - nHit + 0.5) / (nHit + 0.5) );
+        if( idf<=0.0 ) idf = 1e-6;
+        p->aIDF[i] = idf;
+      }
+    }
+
+    if( rc!=SQLITE_OK ){
+      sqlite3_free(p);
+    }else{
+      rc = pApi->xSetAuxdata(pFts, p, sqlite3_free);
+    }
+    if( rc!=SQLITE_OK ) p = 0;
+  }
+  *ppData = p;
+  return rc;
+}
+
+/*
+** Implementation of bm25() function.
+*/
+static void fts5Bm25Function(
+  const Fts5ExtensionApi *pApi,   /* API offered by current FTS version */
+  Fts5Context *pFts,              /* First arg to pass to pApi functions */
+  sqlite3_context *pCtx,          /* Context for returning result/error */
+  int nVal,                       /* Number of values in apVal[] array */
+  sqlite3_value **apVal           /* Array of trailing arguments */
+){
+  const double k1 = 1.2;          /* Constant "k1" from BM25 formula */
+  const double b = 0.75;          /* Constant "b" from BM25 formula */
+  int rc = SQLITE_OK;             /* Error code */
+  double score = 0.0;             /* SQL function return value */
+  Fts5Bm25Data *pData;            /* Values allocated/calculated once only */
+  int i;                          /* Iterator variable */
+  int nInst = 0;                  /* Value returned by xInstCount() */
+  double D = 0.0;                 /* Total number of tokens in row */
+  double *aFreq = 0;              /* Array of phrase freq. for current row */
+
+  /* Calculate the phrase frequency (symbol "f(qi,D)" in the documentation)
+  ** for each phrase in the query for the current row. */
+  rc = fts5Bm25GetData(pApi, pFts, &pData);
+  if( rc==SQLITE_OK ){
+    aFreq = pData->aFreq;
+    memset(aFreq, 0, sizeof(double) * pData->nPhrase);
+    rc = pApi->xInstCount(pFts, &nInst);
+  }
+  for(i=0; rc==SQLITE_OK && i<nInst; i++){
+    int ip; int ic; int io;
+    rc = pApi->xInst(pFts, i, &ip, &ic, &io);
+    if( rc==SQLITE_OK ){
+      double w = (nVal > ic) ? sqlite3_value_double(apVal[ic]) : 1.0;
+      aFreq[ip] += w;
+    }
+  }
+
+  /* Figure out the total size of the current row in tokens. */
+  if( rc==SQLITE_OK ){
+    int nTok;
+    rc = pApi->xColumnSize(pFts, -1, &nTok);
+    D = (double)nTok;
+  }
+
+  /* Determine the BM25 score for the current row. */
+  for(i=0; rc==SQLITE_OK && i<pData->nPhrase; i++){
+    score += pData->aIDF[i] * (
+      ( aFreq[i] * (k1 + 1.0) ) / 
+      ( aFreq[i] + k1 * (1 - b + b * D / pData->avgdl) )
+    );
+  }
+  
+  /* If no error has occurred, return the calculated score. Otherwise,
+  ** throw an SQL exception.  */
+  if( rc==SQLITE_OK ){
+    sqlite3_result_double(pCtx, -1.0 * score);
+  }else{
+    sqlite3_result_error_code(pCtx, rc);
+  }
+}
+
+static int sqlite3Fts5AuxInit(fts5_api *pApi){
+  struct Builtin {
+    const char *zFunc;            /* Function name (nul-terminated) */
+    void *pUserData;              /* User-data pointer */
+    fts5_extension_function xFunc;/* Callback function */
+    void (*xDestroy)(void*);      /* Destructor function */
+  } aBuiltin [] = {
+    { "snippet",   0, fts5SnippetFunction, 0 },
+    { "highlight", 0, fts5HighlightFunction, 0 },
+    { "bm25",      0, fts5Bm25Function,    0 },
+  };
+  int rc = SQLITE_OK;             /* Return code */
+  int i;                          /* To iterate through builtin functions */
+
+  for(i=0; rc==SQLITE_OK && i<ArraySize(aBuiltin); i++){
+    rc = pApi->xCreateFunction(pApi,
+        aBuiltin[i].zFunc,
+        aBuiltin[i].pUserData,
+        aBuiltin[i].xFunc,
+        aBuiltin[i].xDestroy
+    );
+  }
+
+  return rc;
+}
+
+
+
+/*
+** 2014 May 31
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+*/
+
+
+
+/* #include "fts5Int.h" */
+
+static int sqlite3Fts5BufferSize(int *pRc, Fts5Buffer *pBuf, u32 nByte){
+  if( (u32)pBuf->nSpace<nByte ){
+    u32 nNew = pBuf->nSpace ? pBuf->nSpace : 64;
+    u8 *pNew;
+    while( nNew<nByte ){
+      nNew = nNew * 2;
+    }
+    pNew = sqlite3_realloc(pBuf->p, nNew);
+    if( pNew==0 ){
+      *pRc = SQLITE_NOMEM;
+      return 1;
+    }else{
+      pBuf->nSpace = nNew;
+      pBuf->p = pNew;
+    }
+  }
+  return 0;
+}
+
+
+/*
+** Encode value iVal as an SQLite varint and append it to the buffer object
+** pBuf. If an OOM error occurs, set the error code in p.
+*/
+static void sqlite3Fts5BufferAppendVarint(int *pRc, Fts5Buffer *pBuf, i64 iVal){
+  if( fts5BufferGrow(pRc, pBuf, 9) ) return;
+  pBuf->n += sqlite3Fts5PutVarint(&pBuf->p[pBuf->n], iVal);
+}
+
+static void sqlite3Fts5Put32(u8 *aBuf, int iVal){
+  aBuf[0] = (iVal>>24) & 0x00FF;
+  aBuf[1] = (iVal>>16) & 0x00FF;
+  aBuf[2] = (iVal>> 8) & 0x00FF;
+  aBuf[3] = (iVal>> 0) & 0x00FF;
+}
+
+static int sqlite3Fts5Get32(const u8 *aBuf){
+  return (aBuf[0] << 24) + (aBuf[1] << 16) + (aBuf[2] << 8) + aBuf[3];
+}
+
+/*
+** Append buffer nData/pData to buffer pBuf. If an OOM error occurs, set 
+** the error code in p. If an error has already occurred when this function
+** is called, it is a no-op.
+*/
+static void sqlite3Fts5BufferAppendBlob(
+  int *pRc,
+  Fts5Buffer *pBuf, 
+  u32 nData, 
+  const u8 *pData
+){
+  assert_nc( *pRc || nData>=0 );
+  if( fts5BufferGrow(pRc, pBuf, nData) ) return;
+  memcpy(&pBuf->p[pBuf->n], pData, nData);
+  pBuf->n += nData;
+}
+
+/*
+** Append the nul-terminated string zStr to the buffer pBuf. This function
+** ensures that the byte following the buffer data is set to 0x00, even 
+** though this byte is not included in the pBuf->n count.
+*/
+static void sqlite3Fts5BufferAppendString(
+  int *pRc,
+  Fts5Buffer *pBuf, 
+  const char *zStr
+){
+  int nStr = (int)strlen(zStr);
+  sqlite3Fts5BufferAppendBlob(pRc, pBuf, nStr+1, (const u8*)zStr);
+  pBuf->n--;
+}
+
+/*
+** Argument zFmt is a printf() style format string. This function performs
+** the printf() style processing, then appends the results to buffer pBuf.
+**
+** Like sqlite3Fts5BufferAppendString(), this function ensures that the byte 
+** following the buffer data is set to 0x00, even though this byte is not
+** included in the pBuf->n count.
+*/ 
+static void sqlite3Fts5BufferAppendPrintf(
+  int *pRc,
+  Fts5Buffer *pBuf, 
+  char *zFmt, ...
+){
+  if( *pRc==SQLITE_OK ){
+    char *zTmp;
+    va_list ap;
+    va_start(ap, zFmt);
+    zTmp = sqlite3_vmprintf(zFmt, ap);
+    va_end(ap);
+
+    if( zTmp==0 ){
+      *pRc = SQLITE_NOMEM;
+    }else{
+      sqlite3Fts5BufferAppendString(pRc, pBuf, zTmp);
+      sqlite3_free(zTmp);
+    }
+  }
+}
+
+static char *sqlite3Fts5Mprintf(int *pRc, const char *zFmt, ...){
+  char *zRet = 0;
+  if( *pRc==SQLITE_OK ){
+    va_list ap;
+    va_start(ap, zFmt);
+    zRet = sqlite3_vmprintf(zFmt, ap);
+    va_end(ap);
+    if( zRet==0 ){
+      *pRc = SQLITE_NOMEM; 
+    }
+  }
+  return zRet;
+}
+ 
+
+/*
+** Free any buffer allocated by pBuf. Zero the structure before returning.
+*/
+static void sqlite3Fts5BufferFree(Fts5Buffer *pBuf){
+  sqlite3_free(pBuf->p);
+  memset(pBuf, 0, sizeof(Fts5Buffer));
+}
+
+/*
+** Zero the contents of the buffer object. But do not free the associated 
+** memory allocation.
+*/
+static void sqlite3Fts5BufferZero(Fts5Buffer *pBuf){
+  pBuf->n = 0;
+}
+
+/*
+** Set the buffer to contain nData/pData. If an OOM error occurs, leave an
+** the error code in p. If an error has already occurred when this function
+** is called, it is a no-op.
+*/
+static void sqlite3Fts5BufferSet(
+  int *pRc,
+  Fts5Buffer *pBuf, 
+  int nData, 
+  const u8 *pData
+){
+  pBuf->n = 0;
+  sqlite3Fts5BufferAppendBlob(pRc, pBuf, nData, pData);
+}
+
+static int sqlite3Fts5PoslistNext64(
+  const u8 *a, int n,             /* Buffer containing poslist */
+  int *pi,                        /* IN/OUT: Offset within a[] */
+  i64 *piOff                      /* IN/OUT: Current offset */
+){
+  int i = *pi;
+  if( i>=n ){
+    /* EOF */
+    *piOff = -1;
+    return 1;  
+  }else{
+    i64 iOff = *piOff;
+    int iVal;
+    fts5FastGetVarint32(a, i, iVal);
+    if( iVal==1 ){
+      fts5FastGetVarint32(a, i, iVal);
+      iOff = ((i64)iVal) << 32;
+      fts5FastGetVarint32(a, i, iVal);
+    }
+    *piOff = iOff + (iVal-2);
+    *pi = i;
+    return 0;
+  }
+}
+
+
+/*
+** Advance the iterator object passed as the only argument. Return true
+** if the iterator reaches EOF, or false otherwise.
+*/
+static int sqlite3Fts5PoslistReaderNext(Fts5PoslistReader *pIter){
+  if( sqlite3Fts5PoslistNext64(pIter->a, pIter->n, &pIter->i, &pIter->iPos) ){
+    pIter->bEof = 1;
+  }
+  return pIter->bEof;
+}
+
+static int sqlite3Fts5PoslistReaderInit(
+  const u8 *a, int n,             /* Poslist buffer to iterate through */
+  Fts5PoslistReader *pIter        /* Iterator object to initialize */
+){
+  memset(pIter, 0, sizeof(*pIter));
+  pIter->a = a;
+  pIter->n = n;
+  sqlite3Fts5PoslistReaderNext(pIter);
+  return pIter->bEof;
+}
+
+/*
+** Append position iPos to the position list being accumulated in buffer
+** pBuf, which must be already be large enough to hold the new data.
+** The previous position written to this list is *piPrev. *piPrev is set
+** to iPos before returning.
+*/
+static void sqlite3Fts5PoslistSafeAppend(
+  Fts5Buffer *pBuf, 
+  i64 *piPrev, 
+  i64 iPos
+){
+  static const i64 colmask = ((i64)(0x7FFFFFFF)) << 32;
+  if( (iPos & colmask) != (*piPrev & colmask) ){
+    pBuf->p[pBuf->n++] = 1;
+    pBuf->n += sqlite3Fts5PutVarint(&pBuf->p[pBuf->n], (iPos>>32));
+    *piPrev = (iPos & colmask);
+  }
+  pBuf->n += sqlite3Fts5PutVarint(&pBuf->p[pBuf->n], (iPos-*piPrev)+2);
+  *piPrev = iPos;
+}
+
+static int sqlite3Fts5PoslistWriterAppend(
+  Fts5Buffer *pBuf, 
+  Fts5PoslistWriter *pWriter,
+  i64 iPos
+){
+  int rc = 0;   /* Initialized only to suppress erroneous warning from Clang */
+  if( fts5BufferGrow(&rc, pBuf, 5+5+5) ) return rc;
+  sqlite3Fts5PoslistSafeAppend(pBuf, &pWriter->iPrev, iPos);
+  return SQLITE_OK;
+}
+
+static void *sqlite3Fts5MallocZero(int *pRc, int nByte){
+  void *pRet = 0;
+  if( *pRc==SQLITE_OK ){
+    pRet = sqlite3_malloc(nByte);
+    if( pRet==0 && nByte>0 ){
+      *pRc = SQLITE_NOMEM;
+    }else{
+      memset(pRet, 0, nByte);
+    }
+  }
+  return pRet;
+}
+
+/*
+** Return a nul-terminated copy of the string indicated by pIn. If nIn
+** is non-negative, then it is the length of the string in bytes. Otherwise,
+** the length of the string is determined using strlen().
+**
+** It is the responsibility of the caller to eventually free the returned
+** buffer using sqlite3_free(). If an OOM error occurs, NULL is returned. 
+*/
+static char *sqlite3Fts5Strndup(int *pRc, const char *pIn, int nIn){
+  char *zRet = 0;
+  if( *pRc==SQLITE_OK ){
+    if( nIn<0 ){
+      nIn = (int)strlen(pIn);
+    }
+    zRet = (char*)sqlite3_malloc(nIn+1);
+    if( zRet ){
+      memcpy(zRet, pIn, nIn);
+      zRet[nIn] = '\0';
+    }else{
+      *pRc = SQLITE_NOMEM;
+    }
+  }
+  return zRet;
+}
+
+
+/*
+** Return true if character 't' may be part of an FTS5 bareword, or false
+** otherwise. Characters that may be part of barewords:
+**
+**   * All non-ASCII characters,
+**   * The 52 upper and lower case ASCII characters, and
+**   * The 10 integer ASCII characters.
+**   * The underscore character "_" (0x5F).
+**   * The unicode "subsitute" character (0x1A).
+*/
+static int sqlite3Fts5IsBareword(char t){
+  u8 aBareword[128] = {
+    0, 0, 0, 0, 0, 0, 0, 0,    0, 0, 0, 0, 0, 0, 0, 0,   /* 0x00 .. 0x0F */
+    0, 0, 0, 0, 0, 0, 0, 0,    0, 0, 1, 0, 0, 0, 0, 0,   /* 0x10 .. 0x1F */
+    0, 0, 0, 0, 0, 0, 0, 0,    0, 0, 0, 0, 0, 0, 0, 0,   /* 0x20 .. 0x2F */
+    1, 1, 1, 1, 1, 1, 1, 1,    1, 1, 0, 0, 0, 0, 0, 0,   /* 0x30 .. 0x3F */
+    0, 1, 1, 1, 1, 1, 1, 1,    1, 1, 1, 1, 1, 1, 1, 1,   /* 0x40 .. 0x4F */
+    1, 1, 1, 1, 1, 1, 1, 1,    1, 1, 1, 0, 0, 0, 0, 1,   /* 0x50 .. 0x5F */
+    0, 1, 1, 1, 1, 1, 1, 1,    1, 1, 1, 1, 1, 1, 1, 1,   /* 0x60 .. 0x6F */
+    1, 1, 1, 1, 1, 1, 1, 1,    1, 1, 1, 0, 0, 0, 0, 0    /* 0x70 .. 0x7F */
+  };
+
+  return (t & 0x80) || aBareword[(int)t];
+}
+
+
+/*************************************************************************
+*/
+typedef struct Fts5TermsetEntry Fts5TermsetEntry;
+struct Fts5TermsetEntry {
+  char *pTerm;
+  int nTerm;
+  int iIdx;                       /* Index (main or aPrefix[] entry) */
+  Fts5TermsetEntry *pNext;
+};
+
+struct Fts5Termset {
+  Fts5TermsetEntry *apHash[512];
+};
+
+static int sqlite3Fts5TermsetNew(Fts5Termset **pp){
+  int rc = SQLITE_OK;
+  *pp = sqlite3Fts5MallocZero(&rc, sizeof(Fts5Termset));
+  return rc;
+}
+
+static int sqlite3Fts5TermsetAdd(
+  Fts5Termset *p, 
+  int iIdx,
+  const char *pTerm, int nTerm, 
+  int *pbPresent
+){
+  int rc = SQLITE_OK;
+  *pbPresent = 0;
+  if( p ){
+    int i;
+    u32 hash = 13;
+    Fts5TermsetEntry *pEntry;
+
+    /* Calculate a hash value for this term. This is the same hash checksum
+    ** used by the fts5_hash.c module. This is not important for correct
+    ** operation of the module, but is necessary to ensure that some tests
+    ** designed to produce hash table collisions really do work.  */
+    for(i=nTerm-1; i>=0; i--){
+      hash = (hash << 3) ^ hash ^ pTerm[i];
+    }
+    hash = (hash << 3) ^ hash ^ iIdx;
+    hash = hash % ArraySize(p->apHash);
+
+    for(pEntry=p->apHash[hash]; pEntry; pEntry=pEntry->pNext){
+      if( pEntry->iIdx==iIdx 
+          && pEntry->nTerm==nTerm 
+          && memcmp(pEntry->pTerm, pTerm, nTerm)==0 
+      ){
+        *pbPresent = 1;
+        break;
+      }
+    }
+
+    if( pEntry==0 ){
+      pEntry = sqlite3Fts5MallocZero(&rc, sizeof(Fts5TermsetEntry) + nTerm);
+      if( pEntry ){
+        pEntry->pTerm = (char*)&pEntry[1];
+        pEntry->nTerm = nTerm;
+        pEntry->iIdx = iIdx;
+        memcpy(pEntry->pTerm, pTerm, nTerm);
+        pEntry->pNext = p->apHash[hash];
+        p->apHash[hash] = pEntry;
+      }
+    }
+  }
+
+  return rc;
+}
+
+static void sqlite3Fts5TermsetFree(Fts5Termset *p){
+  if( p ){
+    u32 i;
+    for(i=0; i<ArraySize(p->apHash); i++){
+      Fts5TermsetEntry *pEntry = p->apHash[i];
+      while( pEntry ){
+        Fts5TermsetEntry *pDel = pEntry;
+        pEntry = pEntry->pNext;
+        sqlite3_free(pDel);
+      }
+    }
+    sqlite3_free(p);
+  }
+}
+
+/*
+** 2014 Jun 09
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This is an SQLite module implementing full-text search.
+*/
+
+
+/* #include "fts5Int.h" */
+
+#define FTS5_DEFAULT_PAGE_SIZE   4050
+#define FTS5_DEFAULT_AUTOMERGE      4
+#define FTS5_DEFAULT_USERMERGE      4
+#define FTS5_DEFAULT_CRISISMERGE   16
+#define FTS5_DEFAULT_HASHSIZE    (1024*1024)
+
+/* Maximum allowed page size */
+#define FTS5_MAX_PAGE_SIZE (128*1024)
+
+static int fts5_iswhitespace(char x){
+  return (x==' ');
+}
+
+static int fts5_isopenquote(char x){
+  return (x=='"' || x=='\'' || x=='[' || x=='`');
+}
+
+/*
+** Argument pIn points to a character that is part of a nul-terminated 
+** string. Return a pointer to the first character following *pIn in 
+** the string that is not a white-space character.
+*/
+static const char *fts5ConfigSkipWhitespace(const char *pIn){
+  const char *p = pIn;
+  if( p ){
+    while( fts5_iswhitespace(*p) ){ p++; }
+  }
+  return p;
+}
+
+/*
+** Argument pIn points to a character that is part of a nul-terminated 
+** string. Return a pointer to the first character following *pIn in 
+** the string that is not a "bareword" character.
+*/
+static const char *fts5ConfigSkipBareword(const char *pIn){
+  const char *p = pIn;
+  while ( sqlite3Fts5IsBareword(*p) ) p++;
+  if( p==pIn ) p = 0;
+  return p;
+}
+
+static int fts5_isdigit(char a){
+  return (a>='0' && a<='9');
+}
+
+
+
+static const char *fts5ConfigSkipLiteral(const char *pIn){
+  const char *p = pIn;
+  switch( *p ){
+    case 'n': case 'N':
+      if( sqlite3_strnicmp("null", p, 4)==0 ){
+        p = &p[4];
+      }else{
+        p = 0;
+      }
+      break;
+
+    case 'x': case 'X':
+      p++;
+      if( *p=='\'' ){
+        p++;
+        while( (*p>='a' && *p<='f') 
+            || (*p>='A' && *p<='F') 
+            || (*p>='0' && *p<='9') 
+            ){
+          p++;
+        }
+        if( *p=='\'' && 0==((p-pIn)%2) ){
+          p++;
+        }else{
+          p = 0;
+        }
+      }else{
+        p = 0;
+      }
+      break;
+
+    case '\'':
+      p++;
+      while( p ){
+        if( *p=='\'' ){
+          p++;
+          if( *p!='\'' ) break;
+        }
+        p++;
+        if( *p==0 ) p = 0;
+      }
+      break;
+
+    default:
+      /* maybe a number */
+      if( *p=='+' || *p=='-' ) p++;
+      while( fts5_isdigit(*p) ) p++;
+
+      /* At this point, if the literal was an integer, the parse is 
+      ** finished. Or, if it is a floating point value, it may continue
+      ** with either a decimal point or an 'E' character. */
+      if( *p=='.' && fts5_isdigit(p[1]) ){
+        p += 2;
+        while( fts5_isdigit(*p) ) p++;
+      }
+      if( p==pIn ) p = 0;
+
+      break;
+  }
+
+  return p;
+}
+
+/*
+** The first character of the string pointed to by argument z is guaranteed
+** to be an open-quote character (see function fts5_isopenquote()).
+**
+** This function searches for the corresponding close-quote character within
+** the string and, if found, dequotes the string in place and adds a new
+** nul-terminator byte.
+**
+** If the close-quote is found, the value returned is the byte offset of
+** the character immediately following it. Or, if the close-quote is not 
+** found, -1 is returned. If -1 is returned, the buffer is left in an 
+** undefined state.
+*/
+static int fts5Dequote(char *z){
+  char q;
+  int iIn = 1;
+  int iOut = 0;
+  q = z[0];
+
+  /* Set stack variable q to the close-quote character */
+  assert( q=='[' || q=='\'' || q=='"' || q=='`' );
+  if( q=='[' ) q = ']';  
+
+  while( ALWAYS(z[iIn]) ){
+    if( z[iIn]==q ){
+      if( z[iIn+1]!=q ){
+        /* Character iIn was the close quote. */
+        iIn++;
+        break;
+      }else{
+        /* Character iIn and iIn+1 form an escaped quote character. Skip
+        ** the input cursor past both and copy a single quote character 
+        ** to the output buffer. */
+        iIn += 2;
+        z[iOut++] = q;
+      }
+    }else{
+      z[iOut++] = z[iIn++];
+    }
+  }
+
+  z[iOut] = '\0';
+  return iIn;
+}
+
+/*
+** Convert an SQL-style quoted string into a normal string by removing
+** the quote characters.  The conversion is done in-place.  If the
+** input does not begin with a quote character, then this routine
+** is a no-op.
+**
+** Examples:
+**
+**     "abc"   becomes   abc
+**     'xyz'   becomes   xyz
+**     [pqr]   becomes   pqr
+**     `mno`   becomes   mno
+*/
+static void sqlite3Fts5Dequote(char *z){
+  char quote;                     /* Quote character (if any ) */
+
+  assert( 0==fts5_iswhitespace(z[0]) );
+  quote = z[0];
+  if( quote=='[' || quote=='\'' || quote=='"' || quote=='`' ){
+    fts5Dequote(z);
+  }
+}
+
+
+struct Fts5Enum {
+  const char *zName;
+  int eVal;
+};
+typedef struct Fts5Enum Fts5Enum;
+
+static int fts5ConfigSetEnum(
+  const Fts5Enum *aEnum, 
+  const char *zEnum, 
+  int *peVal
+){
+  int nEnum = (int)strlen(zEnum);
+  int i;
+  int iVal = -1;
+
+  for(i=0; aEnum[i].zName; i++){
+    if( sqlite3_strnicmp(aEnum[i].zName, zEnum, nEnum)==0 ){
+      if( iVal>=0 ) return SQLITE_ERROR;
+      iVal = aEnum[i].eVal;
+    }
+  }
+
+  *peVal = iVal;
+  return iVal<0 ? SQLITE_ERROR : SQLITE_OK;
+}
+
+/*
+** Parse a "special" CREATE VIRTUAL TABLE directive and update
+** configuration object pConfig as appropriate.
+**
+** If successful, object pConfig is updated and SQLITE_OK returned. If
+** an error occurs, an SQLite error code is returned and an error message
+** may be left in *pzErr. It is the responsibility of the caller to
+** eventually free any such error message using sqlite3_free().
+*/
+static int fts5ConfigParseSpecial(
+  Fts5Global *pGlobal,
+  Fts5Config *pConfig,            /* Configuration object to update */
+  const char *zCmd,               /* Special command to parse */
+  const char *zArg,               /* Argument to parse */
+  char **pzErr                    /* OUT: Error message */
+){
+  int rc = SQLITE_OK;
+  int nCmd = (int)strlen(zCmd);
+  if( sqlite3_strnicmp("prefix", zCmd, nCmd)==0 ){
+    const int nByte = sizeof(int) * FTS5_MAX_PREFIX_INDEXES;
+    const char *p;
+    int bFirst = 1;
+    if( pConfig->aPrefix==0 ){
+      pConfig->aPrefix = sqlite3Fts5MallocZero(&rc, nByte);
+      if( rc ) return rc;
+    }
+
+    p = zArg;
+    while( 1 ){
+      int nPre = 0;
+
+      while( p[0]==' ' ) p++;
+      if( bFirst==0 && p[0]==',' ){
+        p++;
+        while( p[0]==' ' ) p++;
+      }else if( p[0]=='\0' ){
+        break;
+      }
+      if( p[0]<'0' || p[0]>'9' ){
+        *pzErr = sqlite3_mprintf("malformed prefix=... directive");
+        rc = SQLITE_ERROR;
+        break;
+      }
+
+      if( pConfig->nPrefix==FTS5_MAX_PREFIX_INDEXES ){
+        *pzErr = sqlite3_mprintf(
+            "too many prefix indexes (max %d)", FTS5_MAX_PREFIX_INDEXES
+        );
+        rc = SQLITE_ERROR;
+        break;
+      }
+
+      while( p[0]>='0' && p[0]<='9' && nPre<1000 ){
+        nPre = nPre*10 + (p[0] - '0');
+        p++;
+      }
+
+      if( nPre<=0 || nPre>=1000 ){
+        *pzErr = sqlite3_mprintf("prefix length out of range (max 999)");
+        rc = SQLITE_ERROR;
+        break;
+      }
+
+      pConfig->aPrefix[pConfig->nPrefix] = nPre;
+      pConfig->nPrefix++;
+      bFirst = 0;
+    }
+    assert( pConfig->nPrefix<=FTS5_MAX_PREFIX_INDEXES );
+    return rc;
+  }
+
+  if( sqlite3_strnicmp("tokenize", zCmd, nCmd)==0 ){
+    const char *p = (const char*)zArg;
+    int nArg = (int)strlen(zArg) + 1;
+    char **azArg = sqlite3Fts5MallocZero(&rc, sizeof(char*) * nArg);
+    char *pDel = sqlite3Fts5MallocZero(&rc, nArg * 2);
+    char *pSpace = pDel;
+
+    if( azArg && pSpace ){
+      if( pConfig->pTok ){
+        *pzErr = sqlite3_mprintf("multiple tokenize=... directives");
+        rc = SQLITE_ERROR;
+      }else{
+        for(nArg=0; p && *p; nArg++){
+          const char *p2 = fts5ConfigSkipWhitespace(p);
+          if( *p2=='\'' ){
+            p = fts5ConfigSkipLiteral(p2);
+          }else{
+            p = fts5ConfigSkipBareword(p2);
+          }
+          if( p ){
+            memcpy(pSpace, p2, p-p2);
+            azArg[nArg] = pSpace;
+            sqlite3Fts5Dequote(pSpace);
+            pSpace += (p - p2) + 1;
+            p = fts5ConfigSkipWhitespace(p);
+          }
+        }
+        if( p==0 ){
+          *pzErr = sqlite3_mprintf("parse error in tokenize directive");
+          rc = SQLITE_ERROR;
+        }else{
+          rc = sqlite3Fts5GetTokenizer(pGlobal, 
+              (const char**)azArg, nArg, &pConfig->pTok, &pConfig->pTokApi,
+              pzErr
+          );
+        }
+      }
+    }
+
+    sqlite3_free(azArg);
+    sqlite3_free(pDel);
+    return rc;
+  }
+
+  if( sqlite3_strnicmp("content", zCmd, nCmd)==0 ){
+    if( pConfig->eContent!=FTS5_CONTENT_NORMAL ){
+      *pzErr = sqlite3_mprintf("multiple content=... directives");
+      rc = SQLITE_ERROR;
+    }else{
+      if( zArg[0] ){
+        pConfig->eContent = FTS5_CONTENT_EXTERNAL;
+        pConfig->zContent = sqlite3Fts5Mprintf(&rc, "%Q.%Q", pConfig->zDb,zArg);
+      }else{
+        pConfig->eContent = FTS5_CONTENT_NONE;
+      }
+    }
+    return rc;
+  }
+
+  if( sqlite3_strnicmp("content_rowid", zCmd, nCmd)==0 ){
+    if( pConfig->zContentRowid ){
+      *pzErr = sqlite3_mprintf("multiple content_rowid=... directives");
+      rc = SQLITE_ERROR;
+    }else{
+      pConfig->zContentRowid = sqlite3Fts5Strndup(&rc, zArg, -1);
+    }
+    return rc;
+  }
+
+  if( sqlite3_strnicmp("columnsize", zCmd, nCmd)==0 ){
+    if( (zArg[0]!='0' && zArg[0]!='1') || zArg[1]!='\0' ){
+      *pzErr = sqlite3_mprintf("malformed columnsize=... directive");
+      rc = SQLITE_ERROR;
+    }else{
+      pConfig->bColumnsize = (zArg[0]=='1');
+    }
+    return rc;
+  }
+
+  if( sqlite3_strnicmp("detail", zCmd, nCmd)==0 ){
+    const Fts5Enum aDetail[] = {
+      { "none", FTS5_DETAIL_NONE },
+      { "full", FTS5_DETAIL_FULL },
+      { "columns", FTS5_DETAIL_COLUMNS },
+      { 0, 0 }
+    };
+
+    if( (rc = fts5ConfigSetEnum(aDetail, zArg, &pConfig->eDetail)) ){
+      *pzErr = sqlite3_mprintf("malformed detail=... directive");
+    }
+    return rc;
+  }
+
+  *pzErr = sqlite3_mprintf("unrecognized option: \"%.*s\"", nCmd, zCmd);
+  return SQLITE_ERROR;
+}
+
+/*
+** Allocate an instance of the default tokenizer ("simple") at 
+** Fts5Config.pTokenizer. Return SQLITE_OK if successful, or an SQLite error
+** code if an error occurs.
+*/
+static int fts5ConfigDefaultTokenizer(Fts5Global *pGlobal, Fts5Config *pConfig){
+  assert( pConfig->pTok==0 && pConfig->pTokApi==0 );
+  return sqlite3Fts5GetTokenizer(
+      pGlobal, 0, 0, &pConfig->pTok, &pConfig->pTokApi, 0
+  );
+}
+
+/*
+** Gobble up the first bareword or quoted word from the input buffer zIn.
+** Return a pointer to the character immediately following the last in
+** the gobbled word if successful, or a NULL pointer otherwise (failed
+** to find close-quote character).
+**
+** Before returning, set pzOut to point to a new buffer containing a
+** nul-terminated, dequoted copy of the gobbled word. If the word was
+** quoted, *pbQuoted is also set to 1 before returning.
+**
+** If *pRc is other than SQLITE_OK when this function is called, it is
+** a no-op (NULL is returned). Otherwise, if an OOM occurs within this
+** function, *pRc is set to SQLITE_NOMEM before returning. *pRc is *not*
+** set if a parse error (failed to find close quote) occurs.
+*/
+static const char *fts5ConfigGobbleWord(
+  int *pRc,                       /* IN/OUT: Error code */
+  const char *zIn,                /* Buffer to gobble string/bareword from */
+  char **pzOut,                   /* OUT: malloc'd buffer containing str/bw */
+  int *pbQuoted                   /* OUT: Set to true if dequoting required */
+){
+  const char *zRet = 0;
+
+  int nIn = (int)strlen(zIn);
+  char *zOut = sqlite3_malloc(nIn+1);
+
+  assert( *pRc==SQLITE_OK );
+  *pbQuoted = 0;
+  *pzOut = 0;
+
+  if( zOut==0 ){
+    *pRc = SQLITE_NOMEM;
+  }else{
+    memcpy(zOut, zIn, nIn+1);
+    if( fts5_isopenquote(zOut[0]) ){
+      int ii = fts5Dequote(zOut);
+      zRet = &zIn[ii];
+      *pbQuoted = 1;
+    }else{
+      zRet = fts5ConfigSkipBareword(zIn);
+      if( zRet ){
+        zOut[zRet-zIn] = '\0';
+      }
+    }
+  }
+
+  if( zRet==0 ){
+    sqlite3_free(zOut);
+  }else{
+    *pzOut = zOut;
+  }
+
+  return zRet;
+}
+
+static int fts5ConfigParseColumn(
+  Fts5Config *p, 
+  char *zCol, 
+  char *zArg, 
+  char **pzErr
+){
+  int rc = SQLITE_OK;
+  if( 0==sqlite3_stricmp(zCol, FTS5_RANK_NAME) 
+   || 0==sqlite3_stricmp(zCol, FTS5_ROWID_NAME) 
+  ){
+    *pzErr = sqlite3_mprintf("reserved fts5 column name: %s", zCol);
+    rc = SQLITE_ERROR;
+  }else if( zArg ){
+    if( 0==sqlite3_stricmp(zArg, "unindexed") ){
+      p->abUnindexed[p->nCol] = 1;
+    }else{
+      *pzErr = sqlite3_mprintf("unrecognized column option: %s", zArg);
+      rc = SQLITE_ERROR;
+    }
+  }
+
+  p->azCol[p->nCol++] = zCol;
+  return rc;
+}
+
+/*
+** Populate the Fts5Config.zContentExprlist string.
+*/
+static int fts5ConfigMakeExprlist(Fts5Config *p){
+  int i;
+  int rc = SQLITE_OK;
+  Fts5Buffer buf = {0, 0, 0};
+
+  sqlite3Fts5BufferAppendPrintf(&rc, &buf, "T.%Q", p->zContentRowid);
+  if( p->eContent!=FTS5_CONTENT_NONE ){
+    for(i=0; i<p->nCol; i++){
+      if( p->eContent==FTS5_CONTENT_EXTERNAL ){
+        sqlite3Fts5BufferAppendPrintf(&rc, &buf, ", T.%Q", p->azCol[i]);
+      }else{
+        sqlite3Fts5BufferAppendPrintf(&rc, &buf, ", T.c%d", i);
+      }
+    }
+  }
+
+  assert( p->zContentExprlist==0 );
+  p->zContentExprlist = (char*)buf.p;
+  return rc;
+}
+
+/*
+** Arguments nArg/azArg contain the string arguments passed to the xCreate
+** or xConnect method of the virtual table. This function attempts to 
+** allocate an instance of Fts5Config containing the results of parsing
+** those arguments.
+**
+** If successful, SQLITE_OK is returned and *ppOut is set to point to the
+** new Fts5Config object. If an error occurs, an SQLite error code is 
+** returned, *ppOut is set to NULL and an error message may be left in
+** *pzErr. It is the responsibility of the caller to eventually free any 
+** such error message using sqlite3_free().
+*/
+static int sqlite3Fts5ConfigParse(
+  Fts5Global *pGlobal,
+  sqlite3 *db,
+  int nArg,                       /* Number of arguments */
+  const char **azArg,             /* Array of nArg CREATE VIRTUAL TABLE args */
+  Fts5Config **ppOut,             /* OUT: Results of parse */
+  char **pzErr                    /* OUT: Error message */
+){
+  int rc = SQLITE_OK;             /* Return code */
+  Fts5Config *pRet;               /* New object to return */
+  int i;
+  int nByte;
+
+  *ppOut = pRet = (Fts5Config*)sqlite3_malloc(sizeof(Fts5Config));
+  if( pRet==0 ) return SQLITE_NOMEM;
+  memset(pRet, 0, sizeof(Fts5Config));
+  pRet->db = db;
+  pRet->iCookie = -1;
+
+  nByte = nArg * (sizeof(char*) + sizeof(u8));
+  pRet->azCol = (char**)sqlite3Fts5MallocZero(&rc, nByte);
+  pRet->abUnindexed = (u8*)&pRet->azCol[nArg];
+  pRet->zDb = sqlite3Fts5Strndup(&rc, azArg[1], -1);
+  pRet->zName = sqlite3Fts5Strndup(&rc, azArg[2], -1);
+  pRet->bColumnsize = 1;
+  pRet->eDetail = FTS5_DETAIL_FULL;
+#ifdef SQLITE_DEBUG
+  pRet->bPrefixIndex = 1;
+#endif
+  if( rc==SQLITE_OK && sqlite3_stricmp(pRet->zName, FTS5_RANK_NAME)==0 ){
+    *pzErr = sqlite3_mprintf("reserved fts5 table name: %s", pRet->zName);
+    rc = SQLITE_ERROR;
+  }
+
+  for(i=3; rc==SQLITE_OK && i<nArg; i++){
+    const char *zOrig = azArg[i];
+    const char *z;
+    char *zOne = 0;
+    char *zTwo = 0;
+    int bOption = 0;
+    int bMustBeCol = 0;
+
+    z = fts5ConfigGobbleWord(&rc, zOrig, &zOne, &bMustBeCol);
+    z = fts5ConfigSkipWhitespace(z);
+    if( z && *z=='=' ){
+      bOption = 1;
+      z++;
+      if( bMustBeCol ) z = 0;
+    }
+    z = fts5ConfigSkipWhitespace(z);
+    if( z && z[0] ){
+      int bDummy;
+      z = fts5ConfigGobbleWord(&rc, z, &zTwo, &bDummy);
+      if( z && z[0] ) z = 0;
+    }
+
+    if( rc==SQLITE_OK ){
+      if( z==0 ){
+        *pzErr = sqlite3_mprintf("parse error in \"%s\"", zOrig);
+        rc = SQLITE_ERROR;
+      }else{
+        if( bOption ){
+          rc = fts5ConfigParseSpecial(pGlobal, pRet, zOne, zTwo?zTwo:"", pzErr);
+        }else{
+          rc = fts5ConfigParseColumn(pRet, zOne, zTwo, pzErr);
+          zOne = 0;
+        }
+      }
+    }
+
+    sqlite3_free(zOne);
+    sqlite3_free(zTwo);
+  }
+
+  /* If a tokenizer= option was successfully parsed, the tokenizer has
+  ** already been allocated. Otherwise, allocate an instance of the default
+  ** tokenizer (unicode61) now.  */
+  if( rc==SQLITE_OK && pRet->pTok==0 ){
+    rc = fts5ConfigDefaultTokenizer(pGlobal, pRet);
+  }
+
+  /* If no zContent option was specified, fill in the default values. */
+  if( rc==SQLITE_OK && pRet->zContent==0 ){
+    const char *zTail = 0;
+    assert( pRet->eContent==FTS5_CONTENT_NORMAL 
+         || pRet->eContent==FTS5_CONTENT_NONE 
+    );
+    if( pRet->eContent==FTS5_CONTENT_NORMAL ){
+      zTail = "content";
+    }else if( pRet->bColumnsize ){
+      zTail = "docsize";
+    }
+
+    if( zTail ){
+      pRet->zContent = sqlite3Fts5Mprintf(
+          &rc, "%Q.'%q_%s'", pRet->zDb, pRet->zName, zTail
+      );
+    }
+  }
+
+  if( rc==SQLITE_OK && pRet->zContentRowid==0 ){
+    pRet->zContentRowid = sqlite3Fts5Strndup(&rc, "rowid", -1);
+  }
+
+  /* Formulate the zContentExprlist text */
+  if( rc==SQLITE_OK ){
+    rc = fts5ConfigMakeExprlist(pRet);
+  }
+
+  if( rc!=SQLITE_OK ){
+    sqlite3Fts5ConfigFree(pRet);
+    *ppOut = 0;
+  }
+  return rc;
+}
+
+/*
+** Free the configuration object passed as the only argument.
+*/
+static void sqlite3Fts5ConfigFree(Fts5Config *pConfig){
+  if( pConfig ){
+    int i;
+    if( pConfig->pTok ){
+      pConfig->pTokApi->xDelete(pConfig->pTok);
+    }
+    sqlite3_free(pConfig->zDb);
+    sqlite3_free(pConfig->zName);
+    for(i=0; i<pConfig->nCol; i++){
+      sqlite3_free(pConfig->azCol[i]);
+    }
+    sqlite3_free(pConfig->azCol);
+    sqlite3_free(pConfig->aPrefix);
+    sqlite3_free(pConfig->zRank);
+    sqlite3_free(pConfig->zRankArgs);
+    sqlite3_free(pConfig->zContent);
+    sqlite3_free(pConfig->zContentRowid);
+    sqlite3_free(pConfig->zContentExprlist);
+    sqlite3_free(pConfig);
+  }
+}
+
+/*
+** Call sqlite3_declare_vtab() based on the contents of the configuration
+** object passed as the only argument. Return SQLITE_OK if successful, or
+** an SQLite error code if an error occurs.
+*/
+static int sqlite3Fts5ConfigDeclareVtab(Fts5Config *pConfig){
+  int i;
+  int rc = SQLITE_OK;
+  char *zSql;
+
+  zSql = sqlite3Fts5Mprintf(&rc, "CREATE TABLE x(");
+  for(i=0; zSql && i<pConfig->nCol; i++){
+    const char *zSep = (i==0?"":", ");
+    zSql = sqlite3Fts5Mprintf(&rc, "%z%s%Q", zSql, zSep, pConfig->azCol[i]);
+  }
+  zSql = sqlite3Fts5Mprintf(&rc, "%z, %Q HIDDEN, %s HIDDEN)", 
+      zSql, pConfig->zName, FTS5_RANK_NAME
+  );
+
+  assert( zSql || rc==SQLITE_NOMEM );
+  if( zSql ){
+    rc = sqlite3_declare_vtab(pConfig->db, zSql);
+    sqlite3_free(zSql);
+  }
+  
+  return rc;
+}
+
+/*
+** Tokenize the text passed via the second and third arguments.
+**
+** The callback is invoked once for each token in the input text. The
+** arguments passed to it are, in order:
+**
+**     void *pCtx          // Copy of 4th argument to sqlite3Fts5Tokenize()
+**     const char *pToken  // Pointer to buffer containing token
+**     int nToken          // Size of token in bytes
+**     int iStart          // Byte offset of start of token within input text
+**     int iEnd            // Byte offset of end of token within input text
+**     int iPos            // Position of token in input (first token is 0)
+**
+** If the callback returns a non-zero value the tokenization is abandoned
+** and no further callbacks are issued. 
+**
+** This function returns SQLITE_OK if successful or an SQLite error code
+** if an error occurs. If the tokenization was abandoned early because
+** the callback returned SQLITE_DONE, this is not an error and this function
+** still returns SQLITE_OK. Or, if the tokenization was abandoned early
+** because the callback returned another non-zero value, it is assumed
+** to be an SQLite error code and returned to the caller.
+*/
+static int sqlite3Fts5Tokenize(
+  Fts5Config *pConfig,            /* FTS5 Configuration object */
+  int flags,                      /* FTS5_TOKENIZE_* flags */
+  const char *pText, int nText,   /* Text to tokenize */
+  void *pCtx,                     /* Context passed to xToken() */
+  int (*xToken)(void*, int, const char*, int, int, int)    /* Callback */
+){
+  if( pText==0 ) return SQLITE_OK;
+  return pConfig->pTokApi->xTokenize(
+      pConfig->pTok, pCtx, flags, pText, nText, xToken
+  );
+}
+
+/*
+** Argument pIn points to the first character in what is expected to be
+** a comma-separated list of SQL literals followed by a ')' character.
+** If it actually is this, return a pointer to the ')'. Otherwise, return
+** NULL to indicate a parse error.
+*/
+static const char *fts5ConfigSkipArgs(const char *pIn){
+  const char *p = pIn;
+  
+  while( 1 ){
+    p = fts5ConfigSkipWhitespace(p);
+    p = fts5ConfigSkipLiteral(p);
+    p = fts5ConfigSkipWhitespace(p);
+    if( p==0 || *p==')' ) break;
+    if( *p!=',' ){
+      p = 0;
+      break;
+    }
+    p++;
+  }
+
+  return p;
+}
+
+/*
+** Parameter zIn contains a rank() function specification. The format of 
+** this is:
+**
+**   + Bareword (function name)
+**   + Open parenthesis - "("
+**   + Zero or more SQL literals in a comma separated list
+**   + Close parenthesis - ")"
+*/
+static int sqlite3Fts5ConfigParseRank(
+  const char *zIn,                /* Input string */
+  char **pzRank,                  /* OUT: Rank function name */
+  char **pzRankArgs               /* OUT: Rank function arguments */
+){
+  const char *p = zIn;
+  const char *pRank;
+  char *zRank = 0;
+  char *zRankArgs = 0;
+  int rc = SQLITE_OK;
+
+  *pzRank = 0;
+  *pzRankArgs = 0;
+
+  if( p==0 ){
+    rc = SQLITE_ERROR;
+  }else{
+    p = fts5ConfigSkipWhitespace(p);
+    pRank = p;
+    p = fts5ConfigSkipBareword(p);
+
+    if( p ){
+      zRank = sqlite3Fts5MallocZero(&rc, 1 + p - pRank);
+      if( zRank ) memcpy(zRank, pRank, p-pRank);
+    }else{
+      rc = SQLITE_ERROR;
+    }
+
+    if( rc==SQLITE_OK ){
+      p = fts5ConfigSkipWhitespace(p);
+      if( *p!='(' ) rc = SQLITE_ERROR;
+      p++;
+    }
+    if( rc==SQLITE_OK ){
+      const char *pArgs; 
+      p = fts5ConfigSkipWhitespace(p);
+      pArgs = p;
+      if( *p!=')' ){
+        p = fts5ConfigSkipArgs(p);
+        if( p==0 ){
+          rc = SQLITE_ERROR;
+        }else{
+          zRankArgs = sqlite3Fts5MallocZero(&rc, 1 + p - pArgs);
+          if( zRankArgs ) memcpy(zRankArgs, pArgs, p-pArgs);
+        }
+      }
+    }
+  }
+
+  if( rc!=SQLITE_OK ){
+    sqlite3_free(zRank);
+    assert( zRankArgs==0 );
+  }else{
+    *pzRank = zRank;
+    *pzRankArgs = zRankArgs;
+  }
+  return rc;
+}
+
+static int sqlite3Fts5ConfigSetValue(
+  Fts5Config *pConfig, 
+  const char *zKey, 
+  sqlite3_value *pVal,
+  int *pbBadkey
+){
+  int rc = SQLITE_OK;
+
+  if( 0==sqlite3_stricmp(zKey, "pgsz") ){
+    int pgsz = 0;
+    if( SQLITE_INTEGER==sqlite3_value_numeric_type(pVal) ){
+      pgsz = sqlite3_value_int(pVal);
+    }
+    if( pgsz<=0 || pgsz>FTS5_MAX_PAGE_SIZE ){
+      *pbBadkey = 1;
+    }else{
+      pConfig->pgsz = pgsz;
+    }
+  }
+
+  else if( 0==sqlite3_stricmp(zKey, "hashsize") ){
+    int nHashSize = -1;
+    if( SQLITE_INTEGER==sqlite3_value_numeric_type(pVal) ){
+      nHashSize = sqlite3_value_int(pVal);
+    }
+    if( nHashSize<=0 ){
+      *pbBadkey = 1;
+    }else{
+      pConfig->nHashSize = nHashSize;
+    }
+  }
+
+  else if( 0==sqlite3_stricmp(zKey, "automerge") ){
+    int nAutomerge = -1;
+    if( SQLITE_INTEGER==sqlite3_value_numeric_type(pVal) ){
+      nAutomerge = sqlite3_value_int(pVal);
+    }
+    if( nAutomerge<0 || nAutomerge>64 ){
+      *pbBadkey = 1;
+    }else{
+      if( nAutomerge==1 ) nAutomerge = FTS5_DEFAULT_AUTOMERGE;
+      pConfig->nAutomerge = nAutomerge;
+    }
+  }
+
+  else if( 0==sqlite3_stricmp(zKey, "usermerge") ){
+    int nUsermerge = -1;
+    if( SQLITE_INTEGER==sqlite3_value_numeric_type(pVal) ){
+      nUsermerge = sqlite3_value_int(pVal);
+    }
+    if( nUsermerge<2 || nUsermerge>16 ){
+      *pbBadkey = 1;
+    }else{
+      pConfig->nUsermerge = nUsermerge;
+    }
+  }
+
+  else if( 0==sqlite3_stricmp(zKey, "crisismerge") ){
+    int nCrisisMerge = -1;
+    if( SQLITE_INTEGER==sqlite3_value_numeric_type(pVal) ){
+      nCrisisMerge = sqlite3_value_int(pVal);
+    }
+    if( nCrisisMerge<0 ){
+      *pbBadkey = 1;
+    }else{
+      if( nCrisisMerge<=1 ) nCrisisMerge = FTS5_DEFAULT_CRISISMERGE;
+      pConfig->nCrisisMerge = nCrisisMerge;
+    }
+  }
+
+  else if( 0==sqlite3_stricmp(zKey, "rank") ){
+    const char *zIn = (const char*)sqlite3_value_text(pVal);
+    char *zRank;
+    char *zRankArgs;
+    rc = sqlite3Fts5ConfigParseRank(zIn, &zRank, &zRankArgs);
+    if( rc==SQLITE_OK ){
+      sqlite3_free(pConfig->zRank);
+      sqlite3_free(pConfig->zRankArgs);
+      pConfig->zRank = zRank;
+      pConfig->zRankArgs = zRankArgs;
+    }else if( rc==SQLITE_ERROR ){
+      rc = SQLITE_OK;
+      *pbBadkey = 1;
+    }
+  }else{
+    *pbBadkey = 1;
+  }
+  return rc;
+}
+
+/*
+** Load the contents of the %_config table into memory.
+*/
+static int sqlite3Fts5ConfigLoad(Fts5Config *pConfig, int iCookie){
+  const char *zSelect = "SELECT k, v FROM %Q.'%q_config'";
+  char *zSql;
+  sqlite3_stmt *p = 0;
+  int rc = SQLITE_OK;
+  int iVersion = 0;
+
+  /* Set default values */
+  pConfig->pgsz = FTS5_DEFAULT_PAGE_SIZE;
+  pConfig->nAutomerge = FTS5_DEFAULT_AUTOMERGE;
+  pConfig->nUsermerge = FTS5_DEFAULT_USERMERGE;
+  pConfig->nCrisisMerge = FTS5_DEFAULT_CRISISMERGE;
+  pConfig->nHashSize = FTS5_DEFAULT_HASHSIZE;
+
+  zSql = sqlite3Fts5Mprintf(&rc, zSelect, pConfig->zDb, pConfig->zName);
+  if( zSql ){
+    rc = sqlite3_prepare_v2(pConfig->db, zSql, -1, &p, 0);
+    sqlite3_free(zSql);
+  }
+
+  assert( rc==SQLITE_OK || p==0 );
+  if( rc==SQLITE_OK ){
+    while( SQLITE_ROW==sqlite3_step(p) ){
+      const char *zK = (const char*)sqlite3_column_text(p, 0);
+      sqlite3_value *pVal = sqlite3_column_value(p, 1);
+      if( 0==sqlite3_stricmp(zK, "version") ){
+        iVersion = sqlite3_value_int(pVal);
+      }else{
+        int bDummy = 0;
+        sqlite3Fts5ConfigSetValue(pConfig, zK, pVal, &bDummy);
+      }
+    }
+    rc = sqlite3_finalize(p);
+  }
+  
+  if( rc==SQLITE_OK && iVersion!=FTS5_CURRENT_VERSION ){
+    rc = SQLITE_ERROR;
+    if( pConfig->pzErrmsg ){
+      assert( 0==*pConfig->pzErrmsg );
+      *pConfig->pzErrmsg = sqlite3_mprintf(
+          "invalid fts5 file format (found %d, expected %d) - run 'rebuild'",
+          iVersion, FTS5_CURRENT_VERSION
+      );
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    pConfig->iCookie = iCookie;
+  }
+  return rc;
+}
+
+/*
+** 2014 May 31
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+*/
+
+
+
+/* #include "fts5Int.h" */
+/* #include "fts5parse.h" */
+
+/*
+** All token types in the generated fts5parse.h file are greater than 0.
+*/
+#define FTS5_EOF 0
+
+#define FTS5_LARGEST_INT64  (0xffffffff|(((i64)0x7fffffff)<<32))
+
+typedef struct Fts5ExprTerm Fts5ExprTerm;
+
+/*
+** Functions generated by lemon from fts5parse.y.
+*/
+static void *sqlite3Fts5ParserAlloc(void *(*mallocProc)(u64));
+static void sqlite3Fts5ParserFree(void*, void (*freeProc)(void*));
+static void sqlite3Fts5Parser(void*, int, Fts5Token, Fts5Parse*);
+#ifndef NDEBUG
+/* #include <stdio.h> */
+static void sqlite3Fts5ParserTrace(FILE*, char*);
+#endif
+
+
+struct Fts5Expr {
+  Fts5Index *pIndex;
+  Fts5Config *pConfig;
+  Fts5ExprNode *pRoot;
+  int bDesc;                      /* Iterate in descending rowid order */
+  int nPhrase;                    /* Number of phrases in expression */
+  Fts5ExprPhrase **apExprPhrase;  /* Pointers to phrase objects */
+};
+
+/*
+** eType:
+**   Expression node type. Always one of:
+**
+**       FTS5_AND                 (nChild, apChild valid)
+**       FTS5_OR                  (nChild, apChild valid)
+**       FTS5_NOT                 (nChild, apChild valid)
+**       FTS5_STRING              (pNear valid)
+**       FTS5_TERM                (pNear valid)
+*/
+struct Fts5ExprNode {
+  int eType;                      /* Node type */
+  int bEof;                       /* True at EOF */
+  int bNomatch;                   /* True if entry is not a match */
+
+  /* Next method for this node. */
+  int (*xNext)(Fts5Expr*, Fts5ExprNode*, int, i64);
+
+  i64 iRowid;                     /* Current rowid */
+  Fts5ExprNearset *pNear;         /* For FTS5_STRING - cluster of phrases */
+
+  /* Child nodes. For a NOT node, this array always contains 2 entries. For 
+  ** AND or OR nodes, it contains 2 or more entries.  */
+  int nChild;                     /* Number of child nodes */
+  Fts5ExprNode *apChild[1];       /* Array of child nodes */
+};
+
+#define Fts5NodeIsString(p) ((p)->eType==FTS5_TERM || (p)->eType==FTS5_STRING)
+
+/*
+** Invoke the xNext method of an Fts5ExprNode object. This macro should be
+** used as if it has the same signature as the xNext() methods themselves.
+*/
+#define fts5ExprNodeNext(a,b,c,d) (b)->xNext((a), (b), (c), (d))
+
+/*
+** An instance of the following structure represents a single search term
+** or term prefix.
+*/
+struct Fts5ExprTerm {
+  int bPrefix;                    /* True for a prefix term */
+  char *zTerm;                    /* nul-terminated term */
+  Fts5IndexIter *pIter;           /* Iterator for this term */
+  Fts5ExprTerm *pSynonym;         /* Pointer to first in list of synonyms */
+};
+
+/*
+** A phrase. One or more terms that must appear in a contiguous sequence
+** within a document for it to match.
+*/
+struct Fts5ExprPhrase {
+  Fts5ExprNode *pNode;            /* FTS5_STRING node this phrase is part of */
+  Fts5Buffer poslist;             /* Current position list */
+  int nTerm;                      /* Number of entries in aTerm[] */
+  Fts5ExprTerm aTerm[1];          /* Terms that make up this phrase */
+};
+
+/*
+** One or more phrases that must appear within a certain token distance of
+** each other within each matching document.
+*/
+struct Fts5ExprNearset {
+  int nNear;                      /* NEAR parameter */
+  Fts5Colset *pColset;            /* Columns to search (NULL -> all columns) */
+  int nPhrase;                    /* Number of entries in aPhrase[] array */
+  Fts5ExprPhrase *apPhrase[1];    /* Array of phrase pointers */
+};
+
+
+/*
+** Parse context.
+*/
+struct Fts5Parse {
+  Fts5Config *pConfig;
+  char *zErr;
+  int rc;
+  int nPhrase;                    /* Size of apPhrase array */
+  Fts5ExprPhrase **apPhrase;      /* Array of all phrases */
+  Fts5ExprNode *pExpr;            /* Result of a successful parse */
+};
+
+static void sqlite3Fts5ParseError(Fts5Parse *pParse, const char *zFmt, ...){
+  va_list ap;
+  va_start(ap, zFmt);
+  if( pParse->rc==SQLITE_OK ){
+    pParse->zErr = sqlite3_vmprintf(zFmt, ap);
+    pParse->rc = SQLITE_ERROR;
+  }
+  va_end(ap);
+}
+
+static int fts5ExprIsspace(char t){
+  return t==' ' || t=='\t' || t=='\n' || t=='\r';
+}
+
+/*
+** Read the first token from the nul-terminated string at *pz.
+*/
+static int fts5ExprGetToken(
+  Fts5Parse *pParse, 
+  const char **pz,                /* IN/OUT: Pointer into buffer */
+  Fts5Token *pToken
+){
+  const char *z = *pz;
+  int tok;
+
+  /* Skip past any whitespace */
+  while( fts5ExprIsspace(*z) ) z++;
+
+  pToken->p = z;
+  pToken->n = 1;
+  switch( *z ){
+    case '(':  tok = FTS5_LP;    break;
+    case ')':  tok = FTS5_RP;    break;
+    case '{':  tok = FTS5_LCP;   break;
+    case '}':  tok = FTS5_RCP;   break;
+    case ':':  tok = FTS5_COLON; break;
+    case ',':  tok = FTS5_COMMA; break;
+    case '+':  tok = FTS5_PLUS;  break;
+    case '*':  tok = FTS5_STAR;  break;
+    case '-':  tok = FTS5_MINUS; break;
+    case '\0': tok = FTS5_EOF;   break;
+
+    case '"': {
+      const char *z2;
+      tok = FTS5_STRING;
+
+      for(z2=&z[1]; 1; z2++){
+        if( z2[0]=='"' ){
+          z2++;
+          if( z2[0]!='"' ) break;
+        }
+        if( z2[0]=='\0' ){
+          sqlite3Fts5ParseError(pParse, "unterminated string");
+          return FTS5_EOF;
+        }
+      }
+      pToken->n = (z2 - z);
+      break;
+    }
+
+    default: {
+      const char *z2;
+      if( sqlite3Fts5IsBareword(z[0])==0 ){
+        sqlite3Fts5ParseError(pParse, "fts5: syntax error near \"%.1s\"", z);
+        return FTS5_EOF;
+      }
+      tok = FTS5_STRING;
+      for(z2=&z[1]; sqlite3Fts5IsBareword(*z2); z2++);
+      pToken->n = (z2 - z);
+      if( pToken->n==2 && memcmp(pToken->p, "OR", 2)==0 )  tok = FTS5_OR;
+      if( pToken->n==3 && memcmp(pToken->p, "NOT", 3)==0 ) tok = FTS5_NOT;
+      if( pToken->n==3 && memcmp(pToken->p, "AND", 3)==0 ) tok = FTS5_AND;
+      break;
+    }
+  }
+
+  *pz = &pToken->p[pToken->n];
+  return tok;
+}
+
+static void *fts5ParseAlloc(u64 t){ return sqlite3_malloc((int)t); }
+static void fts5ParseFree(void *p){ sqlite3_free(p); }
+
+static int sqlite3Fts5ExprNew(
+  Fts5Config *pConfig,            /* FTS5 Configuration */
+  const char *zExpr,              /* Expression text */
+  Fts5Expr **ppNew, 
+  char **pzErr
+){
+  Fts5Parse sParse;
+  Fts5Token token;
+  const char *z = zExpr;
+  int t;                          /* Next token type */
+  void *pEngine;
+  Fts5Expr *pNew;
+
+  *ppNew = 0;
+  *pzErr = 0;
+  memset(&sParse, 0, sizeof(sParse));
+  pEngine = sqlite3Fts5ParserAlloc(fts5ParseAlloc);
+  if( pEngine==0 ){ return SQLITE_NOMEM; }
+  sParse.pConfig = pConfig;
+
+  do {
+    t = fts5ExprGetToken(&sParse, &z, &token);
+    sqlite3Fts5Parser(pEngine, t, token, &sParse);
+  }while( sParse.rc==SQLITE_OK && t!=FTS5_EOF );
+  sqlite3Fts5ParserFree(pEngine, fts5ParseFree);
+
+  assert( sParse.rc!=SQLITE_OK || sParse.zErr==0 );
+  if( sParse.rc==SQLITE_OK ){
+    *ppNew = pNew = sqlite3_malloc(sizeof(Fts5Expr));
+    if( pNew==0 ){
+      sParse.rc = SQLITE_NOMEM;
+      sqlite3Fts5ParseNodeFree(sParse.pExpr);
+    }else{
+      if( !sParse.pExpr ){
+        const int nByte = sizeof(Fts5ExprNode);
+        pNew->pRoot = (Fts5ExprNode*)sqlite3Fts5MallocZero(&sParse.rc, nByte);
+        if( pNew->pRoot ){
+          pNew->pRoot->bEof = 1;
+        }
+      }else{
+        pNew->pRoot = sParse.pExpr;
+      }
+      pNew->pIndex = 0;
+      pNew->pConfig = pConfig;
+      pNew->apExprPhrase = sParse.apPhrase;
+      pNew->nPhrase = sParse.nPhrase;
+      sParse.apPhrase = 0;
+    }
+  }else{
+    sqlite3Fts5ParseNodeFree(sParse.pExpr);
+  }
+
+  sqlite3_free(sParse.apPhrase);
+  *pzErr = sParse.zErr;
+  return sParse.rc;
+}
+
+/*
+** Free the expression node object passed as the only argument.
+*/
+static void sqlite3Fts5ParseNodeFree(Fts5ExprNode *p){
+  if( p ){
+    int i;
+    for(i=0; i<p->nChild; i++){
+      sqlite3Fts5ParseNodeFree(p->apChild[i]);
+    }
+    sqlite3Fts5ParseNearsetFree(p->pNear);
+    sqlite3_free(p);
+  }
+}
+
+/*
+** Free the expression object passed as the only argument.
+*/
+static void sqlite3Fts5ExprFree(Fts5Expr *p){
+  if( p ){
+    sqlite3Fts5ParseNodeFree(p->pRoot);
+    sqlite3_free(p->apExprPhrase);
+    sqlite3_free(p);
+  }
+}
+
+/*
+** Argument pTerm must be a synonym iterator. Return the current rowid
+** that it points to.
+*/
+static i64 fts5ExprSynonymRowid(Fts5ExprTerm *pTerm, int bDesc, int *pbEof){
+  i64 iRet = 0;
+  int bRetValid = 0;
+  Fts5ExprTerm *p;
+
+  assert( pTerm->pSynonym );
+  assert( bDesc==0 || bDesc==1 );
+  for(p=pTerm; p; p=p->pSynonym){
+    if( 0==sqlite3Fts5IterEof(p->pIter) ){
+      i64 iRowid = p->pIter->iRowid;
+      if( bRetValid==0 || (bDesc!=(iRowid<iRet)) ){
+        iRet = iRowid;
+        bRetValid = 1;
+      }
+    }
+  }
+
+  if( pbEof && bRetValid==0 ) *pbEof = 1;
+  return iRet;
+}
+
+/*
+** Argument pTerm must be a synonym iterator.
+*/
+static int fts5ExprSynonymList(
+  Fts5ExprTerm *pTerm, 
+  i64 iRowid,
+  Fts5Buffer *pBuf,               /* Use this buffer for space if required */
+  u8 **pa, int *pn
+){
+  Fts5PoslistReader aStatic[4];
+  Fts5PoslistReader *aIter = aStatic;
+  int nIter = 0;
+  int nAlloc = 4;
+  int rc = SQLITE_OK;
+  Fts5ExprTerm *p;
+
+  assert( pTerm->pSynonym );
+  for(p=pTerm; p; p=p->pSynonym){
+    Fts5IndexIter *pIter = p->pIter;
+    if( sqlite3Fts5IterEof(pIter)==0 && pIter->iRowid==iRowid ){
+      if( pIter->nData==0 ) continue;
+      if( nIter==nAlloc ){
+        int nByte = sizeof(Fts5PoslistReader) * nAlloc * 2;
+        Fts5PoslistReader *aNew = (Fts5PoslistReader*)sqlite3_malloc(nByte);
+        if( aNew==0 ){
+          rc = SQLITE_NOMEM;
+          goto synonym_poslist_out;
+        }
+        memcpy(aNew, aIter, sizeof(Fts5PoslistReader) * nIter);
+        nAlloc = nAlloc*2;
+        if( aIter!=aStatic ) sqlite3_free(aIter);
+        aIter = aNew;
+      }
+      sqlite3Fts5PoslistReaderInit(pIter->pData, pIter->nData, &aIter[nIter]);
+      assert( aIter[nIter].bEof==0 );
+      nIter++;
+    }
+  }
+
+  if( nIter==1 ){
+    *pa = (u8*)aIter[0].a;
+    *pn = aIter[0].n;
+  }else{
+    Fts5PoslistWriter writer = {0};
+    i64 iPrev = -1;
+    fts5BufferZero(pBuf);
+    while( 1 ){
+      int i;
+      i64 iMin = FTS5_LARGEST_INT64;
+      for(i=0; i<nIter; i++){
+        if( aIter[i].bEof==0 ){
+          if( aIter[i].iPos==iPrev ){
+            if( sqlite3Fts5PoslistReaderNext(&aIter[i]) ) continue;
+          }
+          if( aIter[i].iPos<iMin ){
+            iMin = aIter[i].iPos;
+          }
+        }
+      }
+      if( iMin==FTS5_LARGEST_INT64 || rc!=SQLITE_OK ) break;
+      rc = sqlite3Fts5PoslistWriterAppend(pBuf, &writer, iMin);
+      iPrev = iMin;
+    }
+    if( rc==SQLITE_OK ){
+      *pa = pBuf->p;
+      *pn = pBuf->n;
+    }
+  }
+
+ synonym_poslist_out:
+  if( aIter!=aStatic ) sqlite3_free(aIter);
+  return rc;
+}
+
+
+/*
+** All individual term iterators in pPhrase are guaranteed to be valid and
+** pointing to the same rowid when this function is called. This function 
+** checks if the current rowid really is a match, and if so populates
+** the pPhrase->poslist buffer accordingly. Output parameter *pbMatch
+** is set to true if this is really a match, or false otherwise.
+**
+** SQLITE_OK is returned if an error occurs, or an SQLite error code 
+** otherwise. It is not considered an error code if the current rowid is 
+** not a match.
+*/
+static int fts5ExprPhraseIsMatch(
+  Fts5ExprNode *pNode,            /* Node pPhrase belongs to */
+  Fts5ExprPhrase *pPhrase,        /* Phrase object to initialize */
+  int *pbMatch                    /* OUT: Set to true if really a match */
+){
+  Fts5PoslistWriter writer = {0};
+  Fts5PoslistReader aStatic[4];
+  Fts5PoslistReader *aIter = aStatic;
+  int i;
+  int rc = SQLITE_OK;
+  
+  fts5BufferZero(&pPhrase->poslist);
+
+  /* If the aStatic[] array is not large enough, allocate a large array
+  ** using sqlite3_malloc(). This approach could be improved upon. */
+  if( pPhrase->nTerm>ArraySize(aStatic) ){
+    int nByte = sizeof(Fts5PoslistReader) * pPhrase->nTerm;
+    aIter = (Fts5PoslistReader*)sqlite3_malloc(nByte);
+    if( !aIter ) return SQLITE_NOMEM;
+  }
+  memset(aIter, 0, sizeof(Fts5PoslistReader) * pPhrase->nTerm);
+
+  /* Initialize a term iterator for each term in the phrase */
+  for(i=0; i<pPhrase->nTerm; i++){
+    Fts5ExprTerm *pTerm = &pPhrase->aTerm[i];
+    int n = 0;
+    int bFlag = 0;
+    u8 *a = 0;
+    if( pTerm->pSynonym ){
+      Fts5Buffer buf = {0, 0, 0};
+      rc = fts5ExprSynonymList(pTerm, pNode->iRowid, &buf, &a, &n);
+      if( rc ){
+        sqlite3_free(a);
+        goto ismatch_out;
+      }
+      if( a==buf.p ) bFlag = 1;
+    }else{
+      a = (u8*)pTerm->pIter->pData;
+      n = pTerm->pIter->nData;
+    }
+    sqlite3Fts5PoslistReaderInit(a, n, &aIter[i]);
+    aIter[i].bFlag = (u8)bFlag;
+    if( aIter[i].bEof ) goto ismatch_out;
+  }
+
+  while( 1 ){
+    int bMatch;
+    i64 iPos = aIter[0].iPos;
+    do {
+      bMatch = 1;
+      for(i=0; i<pPhrase->nTerm; i++){
+        Fts5PoslistReader *pPos = &aIter[i];
+        i64 iAdj = iPos + i;
+        if( pPos->iPos!=iAdj ){
+          bMatch = 0;
+          while( pPos->iPos<iAdj ){
+            if( sqlite3Fts5PoslistReaderNext(pPos) ) goto ismatch_out;
+          }
+          if( pPos->iPos>iAdj ) iPos = pPos->iPos-i;
+        }
+      }
+    }while( bMatch==0 );
+
+    /* Append position iPos to the output */
+    rc = sqlite3Fts5PoslistWriterAppend(&pPhrase->poslist, &writer, iPos);
+    if( rc!=SQLITE_OK ) goto ismatch_out;
+
+    for(i=0; i<pPhrase->nTerm; i++){
+      if( sqlite3Fts5PoslistReaderNext(&aIter[i]) ) goto ismatch_out;
+    }
+  }
+
+ ismatch_out:
+  *pbMatch = (pPhrase->poslist.n>0);
+  for(i=0; i<pPhrase->nTerm; i++){
+    if( aIter[i].bFlag ) sqlite3_free((u8*)aIter[i].a);
+  }
+  if( aIter!=aStatic ) sqlite3_free(aIter);
+  return rc;
+}
+
+typedef struct Fts5LookaheadReader Fts5LookaheadReader;
+struct Fts5LookaheadReader {
+  const u8 *a;                    /* Buffer containing position list */
+  int n;                          /* Size of buffer a[] in bytes */
+  int i;                          /* Current offset in position list */
+  i64 iPos;                       /* Current position */
+  i64 iLookahead;                 /* Next position */
+};
+
+#define FTS5_LOOKAHEAD_EOF (((i64)1) << 62)
+
+static int fts5LookaheadReaderNext(Fts5LookaheadReader *p){
+  p->iPos = p->iLookahead;
+  if( sqlite3Fts5PoslistNext64(p->a, p->n, &p->i, &p->iLookahead) ){
+    p->iLookahead = FTS5_LOOKAHEAD_EOF;
+  }
+  return (p->iPos==FTS5_LOOKAHEAD_EOF);
+}
+
+static int fts5LookaheadReaderInit(
+  const u8 *a, int n,             /* Buffer to read position list from */
+  Fts5LookaheadReader *p          /* Iterator object to initialize */
+){
+  memset(p, 0, sizeof(Fts5LookaheadReader));
+  p->a = a;
+  p->n = n;
+  fts5LookaheadReaderNext(p);
+  return fts5LookaheadReaderNext(p);
+}
+
+typedef struct Fts5NearTrimmer Fts5NearTrimmer;
+struct Fts5NearTrimmer {
+  Fts5LookaheadReader reader;     /* Input iterator */
+  Fts5PoslistWriter writer;       /* Writer context */
+  Fts5Buffer *pOut;               /* Output poslist */
+};
+
+/*
+** The near-set object passed as the first argument contains more than
+** one phrase. All phrases currently point to the same row. The
+** Fts5ExprPhrase.poslist buffers are populated accordingly. This function
+** tests if the current row contains instances of each phrase sufficiently
+** close together to meet the NEAR constraint. Non-zero is returned if it
+** does, or zero otherwise.
+**
+** If in/out parameter (*pRc) is set to other than SQLITE_OK when this
+** function is called, it is a no-op. Or, if an error (e.g. SQLITE_NOMEM)
+** occurs within this function (*pRc) is set accordingly before returning.
+** The return value is undefined in both these cases.
+** 
+** If no error occurs and non-zero (a match) is returned, the position-list
+** of each phrase object is edited to contain only those entries that
+** meet the constraint before returning.
+*/
+static int fts5ExprNearIsMatch(int *pRc, Fts5ExprNearset *pNear){
+  Fts5NearTrimmer aStatic[4];
+  Fts5NearTrimmer *a = aStatic;
+  Fts5ExprPhrase **apPhrase = pNear->apPhrase;
+
+  int i;
+  int rc = *pRc;
+  int bMatch;
+
+  assert( pNear->nPhrase>1 );
+
+  /* If the aStatic[] array is not large enough, allocate a large array
+  ** using sqlite3_malloc(). This approach could be improved upon. */
+  if( pNear->nPhrase>ArraySize(aStatic) ){
+    int nByte = sizeof(Fts5NearTrimmer) * pNear->nPhrase;
+    a = (Fts5NearTrimmer*)sqlite3Fts5MallocZero(&rc, nByte);
+  }else{
+    memset(aStatic, 0, sizeof(aStatic));
+  }
+  if( rc!=SQLITE_OK ){
+    *pRc = rc;
+    return 0;
+  }
+
+  /* Initialize a lookahead iterator for each phrase. After passing the
+  ** buffer and buffer size to the lookaside-reader init function, zero
+  ** the phrase poslist buffer. The new poslist for the phrase (containing
+  ** the same entries as the original with some entries removed on account 
+  ** of the NEAR constraint) is written over the original even as it is
+  ** being read. This is safe as the entries for the new poslist are a
+  ** subset of the old, so it is not possible for data yet to be read to
+  ** be overwritten.  */
+  for(i=0; i<pNear->nPhrase; i++){
+    Fts5Buffer *pPoslist = &apPhrase[i]->poslist;
+    fts5LookaheadReaderInit(pPoslist->p, pPoslist->n, &a[i].reader);
+    pPoslist->n = 0;
+    a[i].pOut = pPoslist;
+  }
+
+  while( 1 ){
+    int iAdv;
+    i64 iMin;
+    i64 iMax;
+
+    /* This block advances the phrase iterators until they point to a set of
+    ** entries that together comprise a match.  */
+    iMax = a[0].reader.iPos;
+    do {
+      bMatch = 1;
+      for(i=0; i<pNear->nPhrase; i++){
+        Fts5LookaheadReader *pPos = &a[i].reader;
+        iMin = iMax - pNear->apPhrase[i]->nTerm - pNear->nNear;
+        if( pPos->iPos<iMin || pPos->iPos>iMax ){
+          bMatch = 0;
+          while( pPos->iPos<iMin ){
+            if( fts5LookaheadReaderNext(pPos) ) goto ismatch_out;
+          }
+          if( pPos->iPos>iMax ) iMax = pPos->iPos;
+        }
+      }
+    }while( bMatch==0 );
+
+    /* Add an entry to each output position list */
+    for(i=0; i<pNear->nPhrase; i++){
+      i64 iPos = a[i].reader.iPos;
+      Fts5PoslistWriter *pWriter = &a[i].writer;
+      if( a[i].pOut->n==0 || iPos!=pWriter->iPrev ){
+        sqlite3Fts5PoslistWriterAppend(a[i].pOut, pWriter, iPos);
+      }
+    }
+
+    iAdv = 0;
+    iMin = a[0].reader.iLookahead;
+    for(i=0; i<pNear->nPhrase; i++){
+      if( a[i].reader.iLookahead < iMin ){
+        iMin = a[i].reader.iLookahead;
+        iAdv = i;
+      }
+    }
+    if( fts5LookaheadReaderNext(&a[iAdv].reader) ) goto ismatch_out;
+  }
+
+  ismatch_out: {
+    int bRet = a[0].pOut->n>0;
+    *pRc = rc;
+    if( a!=aStatic ) sqlite3_free(a);
+    return bRet;
+  }
+}
+
+/*
+** Advance iterator pIter until it points to a value equal to or laster
+** than the initial value of *piLast. If this means the iterator points
+** to a value laster than *piLast, update *piLast to the new lastest value.
+**
+** If the iterator reaches EOF, set *pbEof to true before returning. If
+** an error occurs, set *pRc to an error code. If either *pbEof or *pRc
+** are set, return a non-zero value. Otherwise, return zero.
+*/
+static int fts5ExprAdvanceto(
+  Fts5IndexIter *pIter,           /* Iterator to advance */
+  int bDesc,                      /* True if iterator is "rowid DESC" */
+  i64 *piLast,                    /* IN/OUT: Lastest rowid seen so far */
+  int *pRc,                       /* OUT: Error code */
+  int *pbEof                      /* OUT: Set to true if EOF */
+){
+  i64 iLast = *piLast;
+  i64 iRowid;
+
+  iRowid = pIter->iRowid;
+  if( (bDesc==0 && iLast>iRowid) || (bDesc && iLast<iRowid) ){
+    int rc = sqlite3Fts5IterNextFrom(pIter, iLast);
+    if( rc || sqlite3Fts5IterEof(pIter) ){
+      *pRc = rc;
+      *pbEof = 1;
+      return 1;
+    }
+    iRowid = pIter->iRowid;
+    assert( (bDesc==0 && iRowid>=iLast) || (bDesc==1 && iRowid<=iLast) );
+  }
+  *piLast = iRowid;
+
+  return 0;
+}
+
+static int fts5ExprSynonymAdvanceto(
+  Fts5ExprTerm *pTerm,            /* Term iterator to advance */
+  int bDesc,                      /* True if iterator is "rowid DESC" */
+  i64 *piLast,                    /* IN/OUT: Lastest rowid seen so far */
+  int *pRc                        /* OUT: Error code */
+){
+  int rc = SQLITE_OK;
+  i64 iLast = *piLast;
+  Fts5ExprTerm *p;
+  int bEof = 0;
+
+  for(p=pTerm; rc==SQLITE_OK && p; p=p->pSynonym){
+    if( sqlite3Fts5IterEof(p->pIter)==0 ){
+      i64 iRowid = p->pIter->iRowid;
+      if( (bDesc==0 && iLast>iRowid) || (bDesc && iLast<iRowid) ){
+        rc = sqlite3Fts5IterNextFrom(p->pIter, iLast);
+      }
+    }
+  }
+
+  if( rc!=SQLITE_OK ){
+    *pRc = rc;
+    bEof = 1;
+  }else{
+    *piLast = fts5ExprSynonymRowid(pTerm, bDesc, &bEof);
+  }
+  return bEof;
+}
+
+
+static int fts5ExprNearTest(
+  int *pRc,
+  Fts5Expr *pExpr,                /* Expression that pNear is a part of */
+  Fts5ExprNode *pNode             /* The "NEAR" node (FTS5_STRING) */
+){
+  Fts5ExprNearset *pNear = pNode->pNear;
+  int rc = *pRc;
+
+  if( pExpr->pConfig->eDetail!=FTS5_DETAIL_FULL ){
+    Fts5ExprTerm *pTerm;
+    Fts5ExprPhrase *pPhrase = pNear->apPhrase[0];
+    pPhrase->poslist.n = 0;
+    for(pTerm=&pPhrase->aTerm[0]; pTerm; pTerm=pTerm->pSynonym){
+      Fts5IndexIter *pIter = pTerm->pIter;
+      if( sqlite3Fts5IterEof(pIter)==0 ){
+        if( pIter->iRowid==pNode->iRowid && pIter->nData>0 ){
+          pPhrase->poslist.n = 1;
+        }
+      }
+    }
+    return pPhrase->poslist.n;
+  }else{
+    int i;
+
+    /* Check that each phrase in the nearset matches the current row.
+    ** Populate the pPhrase->poslist buffers at the same time. If any
+    ** phrase is not a match, break out of the loop early.  */
+    for(i=0; rc==SQLITE_OK && i<pNear->nPhrase; i++){
+      Fts5ExprPhrase *pPhrase = pNear->apPhrase[i];
+      if( pPhrase->nTerm>1 || pPhrase->aTerm[0].pSynonym || pNear->pColset ){
+        int bMatch = 0;
+        rc = fts5ExprPhraseIsMatch(pNode, pPhrase, &bMatch);
+        if( bMatch==0 ) break;
+      }else{
+        Fts5IndexIter *pIter = pPhrase->aTerm[0].pIter;
+        fts5BufferSet(&rc, &pPhrase->poslist, pIter->nData, pIter->pData);
+      }
+    }
+
+    *pRc = rc;
+    if( i==pNear->nPhrase && (i==1 || fts5ExprNearIsMatch(pRc, pNear)) ){
+      return 1;
+    }
+    return 0;
+  }
+}
+
+
+/*
+** Initialize all term iterators in the pNear object. If any term is found
+** to match no documents at all, return immediately without initializing any
+** further iterators.
+*/
+static int fts5ExprNearInitAll(
+  Fts5Expr *pExpr,
+  Fts5ExprNode *pNode
+){
+  Fts5ExprNearset *pNear = pNode->pNear;
+  int i, j;
+  int rc = SQLITE_OK;
+  int bEof = 1;
+
+  assert( pNode->bNomatch==0 );
+  for(i=0; rc==SQLITE_OK && i<pNear->nPhrase; i++){
+    Fts5ExprPhrase *pPhrase = pNear->apPhrase[i];
+    for(j=0; j<pPhrase->nTerm; j++){
+      Fts5ExprTerm *pTerm = &pPhrase->aTerm[j];
+      Fts5ExprTerm *p;
+
+      for(p=pTerm; p && rc==SQLITE_OK; p=p->pSynonym){
+        if( p->pIter ){
+          sqlite3Fts5IterClose(p->pIter);
+          p->pIter = 0;
+        }
+        rc = sqlite3Fts5IndexQuery(
+            pExpr->pIndex, p->zTerm, (int)strlen(p->zTerm),
+            (pTerm->bPrefix ? FTS5INDEX_QUERY_PREFIX : 0) |
+            (pExpr->bDesc ? FTS5INDEX_QUERY_DESC : 0),
+            pNear->pColset,
+            &p->pIter
+        );
+        assert( rc==SQLITE_OK || p->pIter==0 );
+        if( p->pIter && 0==sqlite3Fts5IterEof(p->pIter) ){
+          bEof = 0;
+        }
+      }
+
+      if( bEof ) break;
+    }
+    if( bEof ) break;
+  }
+
+  pNode->bEof = bEof;
+  return rc;
+}
+
+/*
+** If pExpr is an ASC iterator, this function returns a value with the
+** same sign as:
+**
+**   (iLhs - iRhs)
+**
+** Otherwise, if this is a DESC iterator, the opposite is returned:
+**
+**   (iRhs - iLhs)
+*/
+static int fts5RowidCmp(
+  Fts5Expr *pExpr,
+  i64 iLhs,
+  i64 iRhs
+){
+  assert( pExpr->bDesc==0 || pExpr->bDesc==1 );
+  if( pExpr->bDesc==0 ){
+    if( iLhs<iRhs ) return -1;
+    return (iLhs > iRhs);
+  }else{
+    if( iLhs>iRhs ) return -1;
+    return (iLhs < iRhs);
+  }
+}
+
+static void fts5ExprSetEof(Fts5ExprNode *pNode){
+  int i;
+  pNode->bEof = 1;
+  pNode->bNomatch = 0;
+  for(i=0; i<pNode->nChild; i++){
+    fts5ExprSetEof(pNode->apChild[i]);
+  }
+}
+
+static void fts5ExprNodeZeroPoslist(Fts5ExprNode *pNode){
+  if( pNode->eType==FTS5_STRING || pNode->eType==FTS5_TERM ){
+    Fts5ExprNearset *pNear = pNode->pNear;
+    int i;
+    for(i=0; i<pNear->nPhrase; i++){
+      Fts5ExprPhrase *pPhrase = pNear->apPhrase[i];
+      pPhrase->poslist.n = 0;
+    }
+  }else{
+    int i;
+    for(i=0; i<pNode->nChild; i++){
+      fts5ExprNodeZeroPoslist(pNode->apChild[i]);
+    }
+  }
+}
+
+
+
+/*
+** Compare the values currently indicated by the two nodes as follows:
+**
+**    res = (*p1) - (*p2)
+**
+** Nodes that point to values that come later in the iteration order are
+** considered to be larger. Nodes at EOF are the largest of all.
+**
+** This means that if the iteration order is ASC, then numerically larger
+** rowids are considered larger. Or if it is the default DESC, numerically
+** smaller rowids are larger.
+*/
+static int fts5NodeCompare(
+  Fts5Expr *pExpr,
+  Fts5ExprNode *p1, 
+  Fts5ExprNode *p2
+){
+  if( p2->bEof ) return -1;
+  if( p1->bEof ) return +1;
+  return fts5RowidCmp(pExpr, p1->iRowid, p2->iRowid);
+}
+
+/*
+** All individual term iterators in pNear are guaranteed to be valid when
+** this function is called. This function checks if all term iterators
+** point to the same rowid, and if not, advances them until they do.
+** If an EOF is reached before this happens, *pbEof is set to true before
+** returning.
+**
+** SQLITE_OK is returned if an error occurs, or an SQLite error code 
+** otherwise. It is not considered an error code if an iterator reaches
+** EOF.
+*/
+static int fts5ExprNodeTest_STRING(
+  Fts5Expr *pExpr,                /* Expression pPhrase belongs to */
+  Fts5ExprNode *pNode
+){
+  Fts5ExprNearset *pNear = pNode->pNear;
+  Fts5ExprPhrase *pLeft = pNear->apPhrase[0];
+  int rc = SQLITE_OK;
+  i64 iLast;                      /* Lastest rowid any iterator points to */
+  int i, j;                       /* Phrase and token index, respectively */
+  int bMatch;                     /* True if all terms are at the same rowid */
+  const int bDesc = pExpr->bDesc;
+
+  /* Check that this node should not be FTS5_TERM */
+  assert( pNear->nPhrase>1 
+       || pNear->apPhrase[0]->nTerm>1 
+       || pNear->apPhrase[0]->aTerm[0].pSynonym
+  );
+
+  /* Initialize iLast, the "lastest" rowid any iterator points to. If the
+  ** iterator skips through rowids in the default ascending order, this means
+  ** the maximum rowid. Or, if the iterator is "ORDER BY rowid DESC", then it
+  ** means the minimum rowid.  */
+  if( pLeft->aTerm[0].pSynonym ){
+    iLast = fts5ExprSynonymRowid(&pLeft->aTerm[0], bDesc, 0);
+  }else{
+    iLast = pLeft->aTerm[0].pIter->iRowid;
+  }
+
+  do {
+    bMatch = 1;
+    for(i=0; i<pNear->nPhrase; i++){
+      Fts5ExprPhrase *pPhrase = pNear->apPhrase[i];
+      for(j=0; j<pPhrase->nTerm; j++){
+        Fts5ExprTerm *pTerm = &pPhrase->aTerm[j];
+        if( pTerm->pSynonym ){
+          i64 iRowid = fts5ExprSynonymRowid(pTerm, bDesc, 0);
+          if( iRowid==iLast ) continue;
+          bMatch = 0;
+          if( fts5ExprSynonymAdvanceto(pTerm, bDesc, &iLast, &rc) ){
+            pNode->bNomatch = 0;
+            pNode->bEof = 1;
+            return rc;
+          }
+        }else{
+          Fts5IndexIter *pIter = pPhrase->aTerm[j].pIter;
+          if( pIter->iRowid==iLast || pIter->bEof ) continue;
+          bMatch = 0;
+          if( fts5ExprAdvanceto(pIter, bDesc, &iLast, &rc, &pNode->bEof) ){
+            return rc;
+          }
+        }
+      }
+    }
+  }while( bMatch==0 );
+
+  pNode->iRowid = iLast;
+  pNode->bNomatch = ((0==fts5ExprNearTest(&rc, pExpr, pNode)) && rc==SQLITE_OK);
+  assert( pNode->bEof==0 || pNode->bNomatch==0 );
+
+  return rc;
+}
+
+/*
+** Advance the first term iterator in the first phrase of pNear. Set output
+** variable *pbEof to true if it reaches EOF or if an error occurs.
+**
+** Return SQLITE_OK if successful, or an SQLite error code if an error
+** occurs.
+*/
+static int fts5ExprNodeNext_STRING(
+  Fts5Expr *pExpr,                /* Expression pPhrase belongs to */
+  Fts5ExprNode *pNode,            /* FTS5_STRING or FTS5_TERM node */
+  int bFromValid,
+  i64 iFrom 
+){
+  Fts5ExprTerm *pTerm = &pNode->pNear->apPhrase[0]->aTerm[0];
+  int rc = SQLITE_OK;
+
+  pNode->bNomatch = 0;
+  if( pTerm->pSynonym ){
+    int bEof = 1;
+    Fts5ExprTerm *p;
+
+    /* Find the firstest rowid any synonym points to. */
+    i64 iRowid = fts5ExprSynonymRowid(pTerm, pExpr->bDesc, 0);
+
+    /* Advance each iterator that currently points to iRowid. Or, if iFrom
+    ** is valid - each iterator that points to a rowid before iFrom.  */
+    for(p=pTerm; p; p=p->pSynonym){
+      if( sqlite3Fts5IterEof(p->pIter)==0 ){
+        i64 ii = p->pIter->iRowid;
+        if( ii==iRowid 
+         || (bFromValid && ii!=iFrom && (ii>iFrom)==pExpr->bDesc) 
+        ){
+          if( bFromValid ){
+            rc = sqlite3Fts5IterNextFrom(p->pIter, iFrom);
+          }else{
+            rc = sqlite3Fts5IterNext(p->pIter);
+          }
+          if( rc!=SQLITE_OK ) break;
+          if( sqlite3Fts5IterEof(p->pIter)==0 ){
+            bEof = 0;
+          }
+        }else{
+          bEof = 0;
+        }
+      }
+    }
+
+    /* Set the EOF flag if either all synonym iterators are at EOF or an
+    ** error has occurred.  */
+    pNode->bEof = (rc || bEof);
+  }else{
+    Fts5IndexIter *pIter = pTerm->pIter;
+
+    assert( Fts5NodeIsString(pNode) );
+    if( bFromValid ){
+      rc = sqlite3Fts5IterNextFrom(pIter, iFrom);
+    }else{
+      rc = sqlite3Fts5IterNext(pIter);
+    }
+
+    pNode->bEof = (rc || sqlite3Fts5IterEof(pIter));
+  }
+
+  if( pNode->bEof==0 ){
+    assert( rc==SQLITE_OK );
+    rc = fts5ExprNodeTest_STRING(pExpr, pNode);
+  }
+
+  return rc;
+}
+
+
+static int fts5ExprNodeTest_TERM(
+  Fts5Expr *pExpr,                /* Expression that pNear is a part of */
+  Fts5ExprNode *pNode             /* The "NEAR" node (FTS5_TERM) */
+){
+  /* As this "NEAR" object is actually a single phrase that consists 
+  ** of a single term only, grab pointers into the poslist managed by the
+  ** fts5_index.c iterator object. This is much faster than synthesizing 
+  ** a new poslist the way we have to for more complicated phrase or NEAR
+  ** expressions.  */
+  Fts5ExprPhrase *pPhrase = pNode->pNear->apPhrase[0];
+  Fts5IndexIter *pIter = pPhrase->aTerm[0].pIter;
+
+  assert( pNode->eType==FTS5_TERM );
+  assert( pNode->pNear->nPhrase==1 && pPhrase->nTerm==1 );
+  assert( pPhrase->aTerm[0].pSynonym==0 );
+
+  pPhrase->poslist.n = pIter->nData;
+  if( pExpr->pConfig->eDetail==FTS5_DETAIL_FULL ){
+    pPhrase->poslist.p = (u8*)pIter->pData;
+  }
+  pNode->iRowid = pIter->iRowid;
+  pNode->bNomatch = (pPhrase->poslist.n==0);
+  return SQLITE_OK;
+}
+
+/*
+** xNext() method for a node of type FTS5_TERM.
+*/
+static int fts5ExprNodeNext_TERM(
+  Fts5Expr *pExpr, 
+  Fts5ExprNode *pNode,
+  int bFromValid,
+  i64 iFrom
+){
+  int rc;
+  Fts5IndexIter *pIter = pNode->pNear->apPhrase[0]->aTerm[0].pIter;
+
+  assert( pNode->bEof==0 );
+  if( bFromValid ){
+    rc = sqlite3Fts5IterNextFrom(pIter, iFrom);
+  }else{
+    rc = sqlite3Fts5IterNext(pIter);
+  }
+  if( rc==SQLITE_OK && sqlite3Fts5IterEof(pIter)==0 ){
+    rc = fts5ExprNodeTest_TERM(pExpr, pNode);
+  }else{
+    pNode->bEof = 1;
+    pNode->bNomatch = 0;
+  }
+  return rc;
+}
+
+static void fts5ExprNodeTest_OR(
+  Fts5Expr *pExpr,                /* Expression of which pNode is a part */
+  Fts5ExprNode *pNode             /* Expression node to test */
+){
+  Fts5ExprNode *pNext = pNode->apChild[0];
+  int i;
+
+  for(i=1; i<pNode->nChild; i++){
+    Fts5ExprNode *pChild = pNode->apChild[i];
+    int cmp = fts5NodeCompare(pExpr, pNext, pChild);
+    if( cmp>0 || (cmp==0 && pChild->bNomatch==0) ){
+      pNext = pChild;
+    }
+  }
+  pNode->iRowid = pNext->iRowid;
+  pNode->bEof = pNext->bEof;
+  pNode->bNomatch = pNext->bNomatch;
+}
+
+static int fts5ExprNodeNext_OR(
+  Fts5Expr *pExpr, 
+  Fts5ExprNode *pNode,
+  int bFromValid,
+  i64 iFrom
+){
+  int i;
+  i64 iLast = pNode->iRowid;
+
+  for(i=0; i<pNode->nChild; i++){
+    Fts5ExprNode *p1 = pNode->apChild[i];
+    assert( p1->bEof || fts5RowidCmp(pExpr, p1->iRowid, iLast)>=0 );
+    if( p1->bEof==0 ){
+      if( (p1->iRowid==iLast) 
+       || (bFromValid && fts5RowidCmp(pExpr, p1->iRowid, iFrom)<0)
+      ){
+        int rc = fts5ExprNodeNext(pExpr, p1, bFromValid, iFrom);
+        if( rc!=SQLITE_OK ) return rc;
+      }
+    }
+  }
+
+  fts5ExprNodeTest_OR(pExpr, pNode);
+  return SQLITE_OK;
+}
+
+/*
+** Argument pNode is an FTS5_AND node.
+*/
+static int fts5ExprNodeTest_AND(
+  Fts5Expr *pExpr,                /* Expression pPhrase belongs to */
+  Fts5ExprNode *pAnd              /* FTS5_AND node to advance */
+){
+  int iChild;
+  i64 iLast = pAnd->iRowid;
+  int rc = SQLITE_OK;
+  int bMatch;
+
+  assert( pAnd->bEof==0 );
+  do {
+    pAnd->bNomatch = 0;
+    bMatch = 1;
+    for(iChild=0; iChild<pAnd->nChild; iChild++){
+      Fts5ExprNode *pChild = pAnd->apChild[iChild];
+      int cmp = fts5RowidCmp(pExpr, iLast, pChild->iRowid);
+      if( cmp>0 ){
+        /* Advance pChild until it points to iLast or laster */
+        rc = fts5ExprNodeNext(pExpr, pChild, 1, iLast);
+        if( rc!=SQLITE_OK ) return rc;
+      }
+
+      /* If the child node is now at EOF, so is the parent AND node. Otherwise,
+      ** the child node is guaranteed to have advanced at least as far as
+      ** rowid iLast. So if it is not at exactly iLast, pChild->iRowid is the
+      ** new lastest rowid seen so far.  */
+      assert( pChild->bEof || fts5RowidCmp(pExpr, iLast, pChild->iRowid)<=0 );
+      if( pChild->bEof ){
+        fts5ExprSetEof(pAnd);
+        bMatch = 1;
+        break;
+      }else if( iLast!=pChild->iRowid ){
+        bMatch = 0;
+        iLast = pChild->iRowid;
+      }
+
+      if( pChild->bNomatch ){
+        pAnd->bNomatch = 1;
+      }
+    }
+  }while( bMatch==0 );
+
+  if( pAnd->bNomatch && pAnd!=pExpr->pRoot ){
+    fts5ExprNodeZeroPoslist(pAnd);
+  }
+  pAnd->iRowid = iLast;
+  return SQLITE_OK;
+}
+
+static int fts5ExprNodeNext_AND(
+  Fts5Expr *pExpr, 
+  Fts5ExprNode *pNode,
+  int bFromValid,
+  i64 iFrom
+){
+  int rc = fts5ExprNodeNext(pExpr, pNode->apChild[0], bFromValid, iFrom);
+  if( rc==SQLITE_OK ){
+    rc = fts5ExprNodeTest_AND(pExpr, pNode);
+  }
+  return rc;
+}
+
+static int fts5ExprNodeTest_NOT(
+  Fts5Expr *pExpr,                /* Expression pPhrase belongs to */
+  Fts5ExprNode *pNode             /* FTS5_NOT node to advance */
+){
+  int rc = SQLITE_OK;
+  Fts5ExprNode *p1 = pNode->apChild[0];
+  Fts5ExprNode *p2 = pNode->apChild[1];
+  assert( pNode->nChild==2 );
+
+  while( rc==SQLITE_OK && p1->bEof==0 ){
+    int cmp = fts5NodeCompare(pExpr, p1, p2);
+    if( cmp>0 ){
+      rc = fts5ExprNodeNext(pExpr, p2, 1, p1->iRowid);
+      cmp = fts5NodeCompare(pExpr, p1, p2);
+    }
+    assert( rc!=SQLITE_OK || cmp<=0 );
+    if( cmp || p2->bNomatch ) break;
+    rc = fts5ExprNodeNext(pExpr, p1, 0, 0);
+  }
+  pNode->bEof = p1->bEof;
+  pNode->bNomatch = p1->bNomatch;
+  pNode->iRowid = p1->iRowid;
+  if( p1->bEof ){
+    fts5ExprNodeZeroPoslist(p2);
+  }
+  return rc;
+}
+
+static int fts5ExprNodeNext_NOT(
+  Fts5Expr *pExpr, 
+  Fts5ExprNode *pNode,
+  int bFromValid,
+  i64 iFrom
+){
+  int rc = fts5ExprNodeNext(pExpr, pNode->apChild[0], bFromValid, iFrom);
+  if( rc==SQLITE_OK ){
+    rc = fts5ExprNodeTest_NOT(pExpr, pNode);
+  }
+  return rc;
+}
+
+/*
+** If pNode currently points to a match, this function returns SQLITE_OK
+** without modifying it. Otherwise, pNode is advanced until it does point
+** to a match or EOF is reached.
+*/
+static int fts5ExprNodeTest(
+  Fts5Expr *pExpr,                /* Expression of which pNode is a part */
+  Fts5ExprNode *pNode             /* Expression node to test */
+){
+  int rc = SQLITE_OK;
+  if( pNode->bEof==0 ){
+    switch( pNode->eType ){
+
+      case FTS5_STRING: {
+        rc = fts5ExprNodeTest_STRING(pExpr, pNode);
+        break;
+      }
+
+      case FTS5_TERM: {
+        rc = fts5ExprNodeTest_TERM(pExpr, pNode);
+        break;
+      }
+
+      case FTS5_AND: {
+        rc = fts5ExprNodeTest_AND(pExpr, pNode);
+        break;
+      }
+
+      case FTS5_OR: {
+        fts5ExprNodeTest_OR(pExpr, pNode);
+        break;
+      }
+
+      default: assert( pNode->eType==FTS5_NOT ); {
+        rc = fts5ExprNodeTest_NOT(pExpr, pNode);
+        break;
+      }
+    }
+  }
+  return rc;
+}
+
+ 
+/*
+** Set node pNode, which is part of expression pExpr, to point to the first
+** match. If there are no matches, set the Node.bEof flag to indicate EOF.
+**
+** Return an SQLite error code if an error occurs, or SQLITE_OK otherwise.
+** It is not an error if there are no matches.
+*/
+static int fts5ExprNodeFirst(Fts5Expr *pExpr, Fts5ExprNode *pNode){
+  int rc = SQLITE_OK;
+  pNode->bEof = 0;
+  pNode->bNomatch = 0;
+
+  if( Fts5NodeIsString(pNode) ){
+    /* Initialize all term iterators in the NEAR object. */
+    rc = fts5ExprNearInitAll(pExpr, pNode);
+  }else if( pNode->xNext==0 ){
+    pNode->bEof = 1;
+  }else{
+    int i;
+    int nEof = 0;
+    for(i=0; i<pNode->nChild && rc==SQLITE_OK; i++){
+      Fts5ExprNode *pChild = pNode->apChild[i];
+      rc = fts5ExprNodeFirst(pExpr, pNode->apChild[i]);
+      assert( pChild->bEof==0 || pChild->bEof==1 );
+      nEof += pChild->bEof;
+    }
+    pNode->iRowid = pNode->apChild[0]->iRowid;
+
+    switch( pNode->eType ){
+      case FTS5_AND:
+        if( nEof>0 ) fts5ExprSetEof(pNode);
+        break;
+
+      case FTS5_OR:
+        if( pNode->nChild==nEof ) fts5ExprSetEof(pNode);
+        break;
+
+      default:
+        assert( pNode->eType==FTS5_NOT );
+        pNode->bEof = pNode->apChild[0]->bEof;
+        break;
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = fts5ExprNodeTest(pExpr, pNode);
+  }
+  return rc;
+}
+
+
+/*
+** Begin iterating through the set of documents in index pIdx matched by
+** the MATCH expression passed as the first argument. If the "bDesc" 
+** parameter is passed a non-zero value, iteration is in descending rowid 
+** order. Or, if it is zero, in ascending order.
+**
+** If iterating in ascending rowid order (bDesc==0), the first document
+** visited is that with the smallest rowid that is larger than or equal
+** to parameter iFirst. Or, if iterating in ascending order (bDesc==1),
+** then the first document visited must have a rowid smaller than or
+** equal to iFirst.
+**
+** Return SQLITE_OK if successful, or an SQLite error code otherwise. It
+** is not considered an error if the query does not match any documents.
+*/
+static int sqlite3Fts5ExprFirst(Fts5Expr *p, Fts5Index *pIdx, i64 iFirst, int bDesc){
+  Fts5ExprNode *pRoot = p->pRoot;
+  int rc;                         /* Return code */
+
+  p->pIndex = pIdx;
+  p->bDesc = bDesc;
+  rc = fts5ExprNodeFirst(p, pRoot);
+
+  /* If not at EOF but the current rowid occurs earlier than iFirst in
+  ** the iteration order, move to document iFirst or later. */
+  if( pRoot->bEof==0 && fts5RowidCmp(p, pRoot->iRowid, iFirst)<0 ){
+    rc = fts5ExprNodeNext(p, pRoot, 1, iFirst);
+  }
+
+  /* If the iterator is not at a real match, skip forward until it is. */
+  while( pRoot->bNomatch ){
+    assert( pRoot->bEof==0 && rc==SQLITE_OK );
+    rc = fts5ExprNodeNext(p, pRoot, 0, 0);
+  }
+  return rc;
+}
+
+/*
+** Move to the next document 
+**
+** Return SQLITE_OK if successful, or an SQLite error code otherwise. It
+** is not considered an error if the query does not match any documents.
+*/
+static int sqlite3Fts5ExprNext(Fts5Expr *p, i64 iLast){
+  int rc;
+  Fts5ExprNode *pRoot = p->pRoot;
+  assert( pRoot->bEof==0 && pRoot->bNomatch==0 );
+  do {
+    rc = fts5ExprNodeNext(p, pRoot, 0, 0);
+    assert( pRoot->bNomatch==0 || (rc==SQLITE_OK && pRoot->bEof==0) );
+  }while( pRoot->bNomatch );
+  if( fts5RowidCmp(p, pRoot->iRowid, iLast)>0 ){
+    pRoot->bEof = 1;
+  }
+  return rc;
+}
+
+static int sqlite3Fts5ExprEof(Fts5Expr *p){
+  return p->pRoot->bEof;
+}
+
+static i64 sqlite3Fts5ExprRowid(Fts5Expr *p){
+  return p->pRoot->iRowid;
+}
+
+static int fts5ParseStringFromToken(Fts5Token *pToken, char **pz){
+  int rc = SQLITE_OK;
+  *pz = sqlite3Fts5Strndup(&rc, pToken->p, pToken->n);
+  return rc;
+}
+
+/*
+** Free the phrase object passed as the only argument.
+*/
+static void fts5ExprPhraseFree(Fts5ExprPhrase *pPhrase){
+  if( pPhrase ){
+    int i;
+    for(i=0; i<pPhrase->nTerm; i++){
+      Fts5ExprTerm *pSyn;
+      Fts5ExprTerm *pNext;
+      Fts5ExprTerm *pTerm = &pPhrase->aTerm[i];
+      sqlite3_free(pTerm->zTerm);
+      sqlite3Fts5IterClose(pTerm->pIter);
+      for(pSyn=pTerm->pSynonym; pSyn; pSyn=pNext){
+        pNext = pSyn->pSynonym;
+        sqlite3Fts5IterClose(pSyn->pIter);
+        fts5BufferFree((Fts5Buffer*)&pSyn[1]);
+        sqlite3_free(pSyn);
+      }
+    }
+    if( pPhrase->poslist.nSpace>0 ) fts5BufferFree(&pPhrase->poslist);
+    sqlite3_free(pPhrase);
+  }
+}
+
+/*
+** If argument pNear is NULL, then a new Fts5ExprNearset object is allocated
+** and populated with pPhrase. Or, if pNear is not NULL, phrase pPhrase is
+** appended to it and the results returned.
+**
+** If an OOM error occurs, both the pNear and pPhrase objects are freed and
+** NULL returned.
+*/
+static Fts5ExprNearset *sqlite3Fts5ParseNearset(
+  Fts5Parse *pParse,              /* Parse context */
+  Fts5ExprNearset *pNear,         /* Existing nearset, or NULL */
+  Fts5ExprPhrase *pPhrase         /* Recently parsed phrase */
+){
+  const int SZALLOC = 8;
+  Fts5ExprNearset *pRet = 0;
+
+  if( pParse->rc==SQLITE_OK ){
+    if( pPhrase==0 ){
+      return pNear;
+    }
+    if( pNear==0 ){
+      int nByte = sizeof(Fts5ExprNearset) + SZALLOC * sizeof(Fts5ExprPhrase*);
+      pRet = sqlite3_malloc(nByte);
+      if( pRet==0 ){
+        pParse->rc = SQLITE_NOMEM;
+      }else{
+        memset(pRet, 0, nByte);
+      }
+    }else if( (pNear->nPhrase % SZALLOC)==0 ){
+      int nNew = pNear->nPhrase + SZALLOC;
+      int nByte = sizeof(Fts5ExprNearset) + nNew * sizeof(Fts5ExprPhrase*);
+
+      pRet = (Fts5ExprNearset*)sqlite3_realloc(pNear, nByte);
+      if( pRet==0 ){
+        pParse->rc = SQLITE_NOMEM;
+      }
+    }else{
+      pRet = pNear;
+    }
+  }
+
+  if( pRet==0 ){
+    assert( pParse->rc!=SQLITE_OK );
+    sqlite3Fts5ParseNearsetFree(pNear);
+    sqlite3Fts5ParsePhraseFree(pPhrase);
+  }else{
+    if( pRet->nPhrase>0 ){
+      Fts5ExprPhrase *pLast = pRet->apPhrase[pRet->nPhrase-1];
+      assert( pLast==pParse->apPhrase[pParse->nPhrase-2] );
+      if( pPhrase->nTerm==0 ){
+        fts5ExprPhraseFree(pPhrase);
+        pRet->nPhrase--;
+        pParse->nPhrase--;
+        pPhrase = pLast;
+      }else if( pLast->nTerm==0 ){
+        fts5ExprPhraseFree(pLast);
+        pParse->apPhrase[pParse->nPhrase-2] = pPhrase;
+        pParse->nPhrase--;
+        pRet->nPhrase--;
+      }
+    }
+    pRet->apPhrase[pRet->nPhrase++] = pPhrase;
+  }
+  return pRet;
+}
+
+typedef struct TokenCtx TokenCtx;
+struct TokenCtx {
+  Fts5ExprPhrase *pPhrase;
+  int rc;
+};
+
+/*
+** Callback for tokenizing terms used by ParseTerm().
+*/
+static int fts5ParseTokenize(
+  void *pContext,                 /* Pointer to Fts5InsertCtx object */
+  int tflags,                     /* Mask of FTS5_TOKEN_* flags */
+  const char *pToken,             /* Buffer containing token */
+  int nToken,                     /* Size of token in bytes */
+  int iUnused1,                   /* Start offset of token */
+  int iUnused2                    /* End offset of token */
+){
+  int rc = SQLITE_OK;
+  const int SZALLOC = 8;
+  TokenCtx *pCtx = (TokenCtx*)pContext;
+  Fts5ExprPhrase *pPhrase = pCtx->pPhrase;
+
+  UNUSED_PARAM2(iUnused1, iUnused2);
+
+  /* If an error has already occurred, this is a no-op */
+  if( pCtx->rc!=SQLITE_OK ) return pCtx->rc;
+  if( nToken>FTS5_MAX_TOKEN_SIZE ) nToken = FTS5_MAX_TOKEN_SIZE;
+
+  if( pPhrase && pPhrase->nTerm>0 && (tflags & FTS5_TOKEN_COLOCATED) ){
+    Fts5ExprTerm *pSyn;
+    int nByte = sizeof(Fts5ExprTerm) + sizeof(Fts5Buffer) + nToken+1;
+    pSyn = (Fts5ExprTerm*)sqlite3_malloc(nByte);
+    if( pSyn==0 ){
+      rc = SQLITE_NOMEM;
+    }else{
+      memset(pSyn, 0, nByte);
+      pSyn->zTerm = ((char*)pSyn) + sizeof(Fts5ExprTerm) + sizeof(Fts5Buffer);
+      memcpy(pSyn->zTerm, pToken, nToken);
+      pSyn->pSynonym = pPhrase->aTerm[pPhrase->nTerm-1].pSynonym;
+      pPhrase->aTerm[pPhrase->nTerm-1].pSynonym = pSyn;
+    }
+  }else{
+    Fts5ExprTerm *pTerm;
+    if( pPhrase==0 || (pPhrase->nTerm % SZALLOC)==0 ){
+      Fts5ExprPhrase *pNew;
+      int nNew = SZALLOC + (pPhrase ? pPhrase->nTerm : 0);
+
+      pNew = (Fts5ExprPhrase*)sqlite3_realloc(pPhrase, 
+          sizeof(Fts5ExprPhrase) + sizeof(Fts5ExprTerm) * nNew
+      );
+      if( pNew==0 ){
+        rc = SQLITE_NOMEM;
+      }else{
+        if( pPhrase==0 ) memset(pNew, 0, sizeof(Fts5ExprPhrase));
+        pCtx->pPhrase = pPhrase = pNew;
+        pNew->nTerm = nNew - SZALLOC;
+      }
+    }
+
+    if( rc==SQLITE_OK ){
+      pTerm = &pPhrase->aTerm[pPhrase->nTerm++];
+      memset(pTerm, 0, sizeof(Fts5ExprTerm));
+      pTerm->zTerm = sqlite3Fts5Strndup(&rc, pToken, nToken);
+    }
+  }
+
+  pCtx->rc = rc;
+  return rc;
+}
+
+
+/*
+** Free the phrase object passed as the only argument.
+*/
+static void sqlite3Fts5ParsePhraseFree(Fts5ExprPhrase *pPhrase){
+  fts5ExprPhraseFree(pPhrase);
+}
+
+/*
+** Free the phrase object passed as the second argument.
+*/
+static void sqlite3Fts5ParseNearsetFree(Fts5ExprNearset *pNear){
+  if( pNear ){
+    int i;
+    for(i=0; i<pNear->nPhrase; i++){
+      fts5ExprPhraseFree(pNear->apPhrase[i]);
+    }
+    sqlite3_free(pNear->pColset);
+    sqlite3_free(pNear);
+  }
+}
+
+static void sqlite3Fts5ParseFinished(Fts5Parse *pParse, Fts5ExprNode *p){
+  assert( pParse->pExpr==0 );
+  pParse->pExpr = p;
+}
+
+/*
+** This function is called by the parser to process a string token. The
+** string may or may not be quoted. In any case it is tokenized and a
+** phrase object consisting of all tokens returned.
+*/
+static Fts5ExprPhrase *sqlite3Fts5ParseTerm(
+  Fts5Parse *pParse,              /* Parse context */
+  Fts5ExprPhrase *pAppend,        /* Phrase to append to */
+  Fts5Token *pToken,              /* String to tokenize */
+  int bPrefix                     /* True if there is a trailing "*" */
+){
+  Fts5Config *pConfig = pParse->pConfig;
+  TokenCtx sCtx;                  /* Context object passed to callback */
+  int rc;                         /* Tokenize return code */
+  char *z = 0;
+
+  memset(&sCtx, 0, sizeof(TokenCtx));
+  sCtx.pPhrase = pAppend;
+
+  rc = fts5ParseStringFromToken(pToken, &z);
+  if( rc==SQLITE_OK ){
+    int flags = FTS5_TOKENIZE_QUERY | (bPrefix ? FTS5_TOKENIZE_QUERY : 0);
+    int n;
+    sqlite3Fts5Dequote(z);
+    n = (int)strlen(z);
+    rc = sqlite3Fts5Tokenize(pConfig, flags, z, n, &sCtx, fts5ParseTokenize);
+  }
+  sqlite3_free(z);
+  if( rc || (rc = sCtx.rc) ){
+    pParse->rc = rc;
+    fts5ExprPhraseFree(sCtx.pPhrase);
+    sCtx.pPhrase = 0;
+  }else{
+
+    if( pAppend==0 ){
+      if( (pParse->nPhrase % 8)==0 ){
+        int nByte = sizeof(Fts5ExprPhrase*) * (pParse->nPhrase + 8);
+        Fts5ExprPhrase **apNew;
+        apNew = (Fts5ExprPhrase**)sqlite3_realloc(pParse->apPhrase, nByte);
+        if( apNew==0 ){
+          pParse->rc = SQLITE_NOMEM;
+          fts5ExprPhraseFree(sCtx.pPhrase);
+          return 0;
+        }
+        pParse->apPhrase = apNew;
+      }
+      pParse->nPhrase++;
+    }
+
+    if( sCtx.pPhrase==0 ){
+      /* This happens when parsing a token or quoted phrase that contains
+      ** no token characters at all. (e.g ... MATCH '""'). */
+      sCtx.pPhrase = sqlite3Fts5MallocZero(&pParse->rc, sizeof(Fts5ExprPhrase));
+    }else if( sCtx.pPhrase->nTerm ){
+      sCtx.pPhrase->aTerm[sCtx.pPhrase->nTerm-1].bPrefix = bPrefix;
+    }
+    pParse->apPhrase[pParse->nPhrase-1] = sCtx.pPhrase;
+  }
+
+  return sCtx.pPhrase;
+}
+
+/*
+** Create a new FTS5 expression by cloning phrase iPhrase of the
+** expression passed as the second argument.
+*/
+static int sqlite3Fts5ExprClonePhrase(
+  Fts5Expr *pExpr, 
+  int iPhrase, 
+  Fts5Expr **ppNew
+){
+  int rc = SQLITE_OK;             /* Return code */
+  Fts5ExprPhrase *pOrig;          /* The phrase extracted from pExpr */
+  Fts5Expr *pNew = 0;             /* Expression to return via *ppNew */
+  TokenCtx sCtx = {0,0};          /* Context object for fts5ParseTokenize */
+
+  pOrig = pExpr->apExprPhrase[iPhrase];
+  pNew = (Fts5Expr*)sqlite3Fts5MallocZero(&rc, sizeof(Fts5Expr));
+  if( rc==SQLITE_OK ){
+    pNew->apExprPhrase = (Fts5ExprPhrase**)sqlite3Fts5MallocZero(&rc, 
+        sizeof(Fts5ExprPhrase*));
+  }
+  if( rc==SQLITE_OK ){
+    pNew->pRoot = (Fts5ExprNode*)sqlite3Fts5MallocZero(&rc, 
+        sizeof(Fts5ExprNode));
+  }
+  if( rc==SQLITE_OK ){
+    pNew->pRoot->pNear = (Fts5ExprNearset*)sqlite3Fts5MallocZero(&rc, 
+        sizeof(Fts5ExprNearset) + sizeof(Fts5ExprPhrase*));
+  }
+  if( rc==SQLITE_OK ){
+    Fts5Colset *pColsetOrig = pOrig->pNode->pNear->pColset;
+    if( pColsetOrig ){
+      int nByte = sizeof(Fts5Colset) + (pColsetOrig->nCol-1) * sizeof(int);
+      Fts5Colset *pColset = (Fts5Colset*)sqlite3Fts5MallocZero(&rc, nByte);
+      if( pColset ){ 
+        memcpy(pColset, pColsetOrig, nByte);
+      }
+      pNew->pRoot->pNear->pColset = pColset;
+    }
+  }
+
+  if( pOrig->nTerm ){
+    int i;                          /* Used to iterate through phrase terms */
+    for(i=0; rc==SQLITE_OK && i<pOrig->nTerm; i++){
+      int tflags = 0;
+      Fts5ExprTerm *p;
+      for(p=&pOrig->aTerm[i]; p && rc==SQLITE_OK; p=p->pSynonym){
+        const char *zTerm = p->zTerm;
+        rc = fts5ParseTokenize((void*)&sCtx, tflags, zTerm, (int)strlen(zTerm),
+            0, 0);
+        tflags = FTS5_TOKEN_COLOCATED;
+      }
+      if( rc==SQLITE_OK ){
+        sCtx.pPhrase->aTerm[i].bPrefix = pOrig->aTerm[i].bPrefix;
+      }
+    }
+  }else{
+    /* This happens when parsing a token or quoted phrase that contains
+    ** no token characters at all. (e.g ... MATCH '""'). */
+    sCtx.pPhrase = sqlite3Fts5MallocZero(&rc, sizeof(Fts5ExprPhrase));
+  }
+
+  if( rc==SQLITE_OK ){
+    /* All the allocations succeeded. Put the expression object together. */
+    pNew->pIndex = pExpr->pIndex;
+    pNew->pConfig = pExpr->pConfig;
+    pNew->nPhrase = 1;
+    pNew->apExprPhrase[0] = sCtx.pPhrase;
+    pNew->pRoot->pNear->apPhrase[0] = sCtx.pPhrase;
+    pNew->pRoot->pNear->nPhrase = 1;
+    sCtx.pPhrase->pNode = pNew->pRoot;
+
+    if( pOrig->nTerm==1 && pOrig->aTerm[0].pSynonym==0 ){
+      pNew->pRoot->eType = FTS5_TERM;
+      pNew->pRoot->xNext = fts5ExprNodeNext_TERM;
+    }else{
+      pNew->pRoot->eType = FTS5_STRING;
+      pNew->pRoot->xNext = fts5ExprNodeNext_STRING;
+    }
+  }else{
+    sqlite3Fts5ExprFree(pNew);
+    fts5ExprPhraseFree(sCtx.pPhrase);
+    pNew = 0;
+  }
+
+  *ppNew = pNew;
+  return rc;
+}
+
+
+/*
+** Token pTok has appeared in a MATCH expression where the NEAR operator
+** is expected. If token pTok does not contain "NEAR", store an error
+** in the pParse object.
+*/
+static void sqlite3Fts5ParseNear(Fts5Parse *pParse, Fts5Token *pTok){
+  if( pTok->n!=4 || memcmp("NEAR", pTok->p, 4) ){
+    sqlite3Fts5ParseError(
+        pParse, "fts5: syntax error near \"%.*s\"", pTok->n, pTok->p
+    );
+  }
+}
+
+static void sqlite3Fts5ParseSetDistance(
+  Fts5Parse *pParse, 
+  Fts5ExprNearset *pNear,
+  Fts5Token *p
+){
+  if( pNear ){
+    int nNear = 0;
+    int i;
+    if( p->n ){
+      for(i=0; i<p->n; i++){
+        char c = (char)p->p[i];
+        if( c<'0' || c>'9' ){
+          sqlite3Fts5ParseError(
+              pParse, "expected integer, got \"%.*s\"", p->n, p->p
+              );
+          return;
+        }
+        nNear = nNear * 10 + (p->p[i] - '0');
+      }
+    }else{
+      nNear = FTS5_DEFAULT_NEARDIST;
+    }
+    pNear->nNear = nNear;
+  }
+}
+
+/*
+** The second argument passed to this function may be NULL, or it may be
+** an existing Fts5Colset object. This function returns a pointer to
+** a new colset object containing the contents of (p) with new value column
+** number iCol appended. 
+**
+** If an OOM error occurs, store an error code in pParse and return NULL.
+** The old colset object (if any) is not freed in this case.
+*/
+static Fts5Colset *fts5ParseColset(
+  Fts5Parse *pParse,              /* Store SQLITE_NOMEM here if required */
+  Fts5Colset *p,                  /* Existing colset object */
+  int iCol                        /* New column to add to colset object */
+){
+  int nCol = p ? p->nCol : 0;     /* Num. columns already in colset object */
+  Fts5Colset *pNew;               /* New colset object to return */
+
+  assert( pParse->rc==SQLITE_OK );
+  assert( iCol>=0 && iCol<pParse->pConfig->nCol );
+
+  pNew = sqlite3_realloc(p, sizeof(Fts5Colset) + sizeof(int)*nCol);
+  if( pNew==0 ){
+    pParse->rc = SQLITE_NOMEM;
+  }else{
+    int *aiCol = pNew->aiCol;
+    int i, j;
+    for(i=0; i<nCol; i++){
+      if( aiCol[i]==iCol ) return pNew;
+      if( aiCol[i]>iCol ) break;
+    }
+    for(j=nCol; j>i; j--){
+      aiCol[j] = aiCol[j-1];
+    }
+    aiCol[i] = iCol;
+    pNew->nCol = nCol+1;
+
+#ifndef NDEBUG
+    /* Check that the array is in order and contains no duplicate entries. */
+    for(i=1; i<pNew->nCol; i++) assert( pNew->aiCol[i]>pNew->aiCol[i-1] );
+#endif
+  }
+
+  return pNew;
+}
+
+/*
+** Allocate and return an Fts5Colset object specifying the inverse of
+** the colset passed as the second argument. Free the colset passed
+** as the second argument before returning.
+*/
+static Fts5Colset *sqlite3Fts5ParseColsetInvert(Fts5Parse *pParse, Fts5Colset *p){
+  Fts5Colset *pRet;
+  int nCol = pParse->pConfig->nCol;
+
+  pRet = (Fts5Colset*)sqlite3Fts5MallocZero(&pParse->rc, 
+      sizeof(Fts5Colset) + sizeof(int)*nCol
+  );
+  if( pRet ){
+    int i;
+    int iOld = 0;
+    for(i=0; i<nCol; i++){
+      if( iOld>=p->nCol || p->aiCol[iOld]!=i ){
+        pRet->aiCol[pRet->nCol++] = i;
+      }else{
+        iOld++;
+      }
+    }
+  }
+
+  sqlite3_free(p);
+  return pRet;
+}
+
+static Fts5Colset *sqlite3Fts5ParseColset(
+  Fts5Parse *pParse,              /* Store SQLITE_NOMEM here if required */
+  Fts5Colset *pColset,            /* Existing colset object */
+  Fts5Token *p
+){
+  Fts5Colset *pRet = 0;
+  int iCol;
+  char *z;                        /* Dequoted copy of token p */
+
+  z = sqlite3Fts5Strndup(&pParse->rc, p->p, p->n);
+  if( pParse->rc==SQLITE_OK ){
+    Fts5Config *pConfig = pParse->pConfig;
+    sqlite3Fts5Dequote(z);
+    for(iCol=0; iCol<pConfig->nCol; iCol++){
+      if( 0==sqlite3_stricmp(pConfig->azCol[iCol], z) ) break;
+    }
+    if( iCol==pConfig->nCol ){
+      sqlite3Fts5ParseError(pParse, "no such column: %s", z);
+    }else{
+      pRet = fts5ParseColset(pParse, pColset, iCol);
+    }
+    sqlite3_free(z);
+  }
+
+  if( pRet==0 ){
+    assert( pParse->rc!=SQLITE_OK );
+    sqlite3_free(pColset);
+  }
+
+  return pRet;
+}
+
+static void sqlite3Fts5ParseSetColset(
+  Fts5Parse *pParse, 
+  Fts5ExprNearset *pNear, 
+  Fts5Colset *pColset 
+){
+  if( pParse->pConfig->eDetail==FTS5_DETAIL_NONE ){
+    pParse->rc = SQLITE_ERROR;
+    pParse->zErr = sqlite3_mprintf(
+      "fts5: column queries are not supported (detail=none)"
+    );
+    sqlite3_free(pColset);
+    return;
+  }
+
+  if( pNear ){
+    pNear->pColset = pColset;
+  }else{
+    sqlite3_free(pColset);
+  }
+}
+
+static void fts5ExprAssignXNext(Fts5ExprNode *pNode){
+  switch( pNode->eType ){
+    case FTS5_STRING: {
+      Fts5ExprNearset *pNear = pNode->pNear;
+      if( pNear->nPhrase==1 && pNear->apPhrase[0]->nTerm==1 
+       && pNear->apPhrase[0]->aTerm[0].pSynonym==0
+      ){
+        pNode->eType = FTS5_TERM;
+        pNode->xNext = fts5ExprNodeNext_TERM;
+      }else{
+        pNode->xNext = fts5ExprNodeNext_STRING;
+      }
+      break;
+    };
+
+    case FTS5_OR: {
+      pNode->xNext = fts5ExprNodeNext_OR;
+      break;
+    };
+
+    case FTS5_AND: {
+      pNode->xNext = fts5ExprNodeNext_AND;
+      break;
+    };
+
+    default: assert( pNode->eType==FTS5_NOT ); {
+      pNode->xNext = fts5ExprNodeNext_NOT;
+      break;
+    };
+  }
+}
+
+static void fts5ExprAddChildren(Fts5ExprNode *p, Fts5ExprNode *pSub){
+  if( p->eType!=FTS5_NOT && pSub->eType==p->eType ){
+    int nByte = sizeof(Fts5ExprNode*) * pSub->nChild;
+    memcpy(&p->apChild[p->nChild], pSub->apChild, nByte);
+    p->nChild += pSub->nChild;
+    sqlite3_free(pSub);
+  }else{
+    p->apChild[p->nChild++] = pSub;
+  }
+}
+
+/*
+** Allocate and return a new expression object. If anything goes wrong (i.e.
+** OOM error), leave an error code in pParse and return NULL.
+*/
+static Fts5ExprNode *sqlite3Fts5ParseNode(
+  Fts5Parse *pParse,              /* Parse context */
+  int eType,                      /* FTS5_STRING, AND, OR or NOT */
+  Fts5ExprNode *pLeft,            /* Left hand child expression */
+  Fts5ExprNode *pRight,           /* Right hand child expression */
+  Fts5ExprNearset *pNear          /* For STRING expressions, the near cluster */
+){
+  Fts5ExprNode *pRet = 0;
+
+  if( pParse->rc==SQLITE_OK ){
+    int nChild = 0;               /* Number of children of returned node */
+    int nByte;                    /* Bytes of space to allocate for this node */
+ 
+    assert( (eType!=FTS5_STRING && !pNear)
+         || (eType==FTS5_STRING && !pLeft && !pRight)
+    );
+    if( eType==FTS5_STRING && pNear==0 ) return 0;
+    if( eType!=FTS5_STRING && pLeft==0 ) return pRight;
+    if( eType!=FTS5_STRING && pRight==0 ) return pLeft;
+
+    if( eType==FTS5_NOT ){
+      nChild = 2;
+    }else if( eType==FTS5_AND || eType==FTS5_OR ){
+      nChild = 2;
+      if( pLeft->eType==eType ) nChild += pLeft->nChild-1;
+      if( pRight->eType==eType ) nChild += pRight->nChild-1;
+    }
+
+    nByte = sizeof(Fts5ExprNode) + sizeof(Fts5ExprNode*)*(nChild-1);
+    pRet = (Fts5ExprNode*)sqlite3Fts5MallocZero(&pParse->rc, nByte);
+
+    if( pRet ){
+      pRet->eType = eType;
+      pRet->pNear = pNear;
+      fts5ExprAssignXNext(pRet);
+      if( eType==FTS5_STRING ){
+        int iPhrase;
+        for(iPhrase=0; iPhrase<pNear->nPhrase; iPhrase++){
+          pNear->apPhrase[iPhrase]->pNode = pRet;
+          if( pNear->apPhrase[iPhrase]->nTerm==0 ){
+            pRet->xNext = 0;
+            pRet->eType = FTS5_EOF;
+          }
+        }
+
+        if( pParse->pConfig->eDetail!=FTS5_DETAIL_FULL 
+         && (pNear->nPhrase!=1 || pNear->apPhrase[0]->nTerm>1)
+        ){
+          assert( pParse->rc==SQLITE_OK );
+          pParse->rc = SQLITE_ERROR;
+          assert( pParse->zErr==0 );
+          pParse->zErr = sqlite3_mprintf(
+              "fts5: %s queries are not supported (detail!=full)", 
+              pNear->nPhrase==1 ? "phrase": "NEAR"
+          );
+          sqlite3_free(pRet);
+          pRet = 0;
+        }
+
+      }else{
+        fts5ExprAddChildren(pRet, pLeft);
+        fts5ExprAddChildren(pRet, pRight);
+      }
+    }
+  }
+
+  if( pRet==0 ){
+    assert( pParse->rc!=SQLITE_OK );
+    sqlite3Fts5ParseNodeFree(pLeft);
+    sqlite3Fts5ParseNodeFree(pRight);
+    sqlite3Fts5ParseNearsetFree(pNear);
+  }
+  return pRet;
+}
+
+static Fts5ExprNode *sqlite3Fts5ParseImplicitAnd(
+  Fts5Parse *pParse,              /* Parse context */
+  Fts5ExprNode *pLeft,            /* Left hand child expression */
+  Fts5ExprNode *pRight            /* Right hand child expression */
+){
+  Fts5ExprNode *pRet = 0;
+  Fts5ExprNode *pPrev;
+
+  if( pParse->rc ){
+    sqlite3Fts5ParseNodeFree(pLeft);
+    sqlite3Fts5ParseNodeFree(pRight);
+  }else{
+
+    assert( pLeft->eType==FTS5_STRING 
+        || pLeft->eType==FTS5_TERM
+        || pLeft->eType==FTS5_EOF
+        || pLeft->eType==FTS5_AND
+    );
+    assert( pRight->eType==FTS5_STRING 
+        || pRight->eType==FTS5_TERM 
+        || pRight->eType==FTS5_EOF 
+    );
+
+    if( pLeft->eType==FTS5_AND ){
+      pPrev = pLeft->apChild[pLeft->nChild-1];
+    }else{
+      pPrev = pLeft;
+    }
+    assert( pPrev->eType==FTS5_STRING 
+        || pPrev->eType==FTS5_TERM 
+        || pPrev->eType==FTS5_EOF 
+        );
+
+    if( pRight->eType==FTS5_EOF ){
+      assert( pParse->apPhrase[pParse->nPhrase-1]==pRight->pNear->apPhrase[0] );
+      sqlite3Fts5ParseNodeFree(pRight);
+      pRet = pLeft;
+      pParse->nPhrase--;
+    }
+    else if( pPrev->eType==FTS5_EOF ){
+      Fts5ExprPhrase **ap;
+
+      if( pPrev==pLeft ){
+        pRet = pRight;
+      }else{
+        pLeft->apChild[pLeft->nChild-1] = pRight;
+        pRet = pLeft;
+      }
+
+      ap = &pParse->apPhrase[pParse->nPhrase-1-pRight->pNear->nPhrase];
+      assert( ap[0]==pPrev->pNear->apPhrase[0] );
+      memmove(ap, &ap[1], sizeof(Fts5ExprPhrase*)*pRight->pNear->nPhrase);
+      pParse->nPhrase--;
+
+      sqlite3Fts5ParseNodeFree(pPrev);
+    }
+    else{
+      pRet = sqlite3Fts5ParseNode(pParse, FTS5_AND, pLeft, pRight, 0);
+    }
+  }
+
+  return pRet;
+}
+
+static char *fts5ExprTermPrint(Fts5ExprTerm *pTerm){
+  int nByte = 0;
+  Fts5ExprTerm *p;
+  char *zQuoted;
+
+  /* Determine the maximum amount of space required. */
+  for(p=pTerm; p; p=p->pSynonym){
+    nByte += (int)strlen(pTerm->zTerm) * 2 + 3 + 2;
+  }
+  zQuoted = sqlite3_malloc(nByte);
+
+  if( zQuoted ){
+    int i = 0;
+    for(p=pTerm; p; p=p->pSynonym){
+      char *zIn = p->zTerm;
+      zQuoted[i++] = '"';
+      while( *zIn ){
+        if( *zIn=='"' ) zQuoted[i++] = '"';
+        zQuoted[i++] = *zIn++;
+      }
+      zQuoted[i++] = '"';
+      if( p->pSynonym ) zQuoted[i++] = '|';
+    }
+    if( pTerm->bPrefix ){
+      zQuoted[i++] = ' ';
+      zQuoted[i++] = '*';
+    }
+    zQuoted[i++] = '\0';
+  }
+  return zQuoted;
+}
+
+static char *fts5PrintfAppend(char *zApp, const char *zFmt, ...){
+  char *zNew;
+  va_list ap;
+  va_start(ap, zFmt);
+  zNew = sqlite3_vmprintf(zFmt, ap);
+  va_end(ap);
+  if( zApp && zNew ){
+    char *zNew2 = sqlite3_mprintf("%s%s", zApp, zNew);
+    sqlite3_free(zNew);
+    zNew = zNew2;
+  }
+  sqlite3_free(zApp);
+  return zNew;
+}
+
+/*
+** Compose a tcl-readable representation of expression pExpr. Return a 
+** pointer to a buffer containing that representation. It is the 
+** responsibility of the caller to at some point free the buffer using 
+** sqlite3_free().
+*/
+static char *fts5ExprPrintTcl(
+  Fts5Config *pConfig, 
+  const char *zNearsetCmd,
+  Fts5ExprNode *pExpr
+){
+  char *zRet = 0;
+  if( pExpr->eType==FTS5_STRING || pExpr->eType==FTS5_TERM ){
+    Fts5ExprNearset *pNear = pExpr->pNear;
+    int i; 
+    int iTerm;
+
+    zRet = fts5PrintfAppend(zRet, "%s ", zNearsetCmd);
+    if( zRet==0 ) return 0;
+    if( pNear->pColset ){
+      int *aiCol = pNear->pColset->aiCol;
+      int nCol = pNear->pColset->nCol;
+      if( nCol==1 ){
+        zRet = fts5PrintfAppend(zRet, "-col %d ", aiCol[0]);
+      }else{
+        zRet = fts5PrintfAppend(zRet, "-col {%d", aiCol[0]);
+        for(i=1; i<pNear->pColset->nCol; i++){
+          zRet = fts5PrintfAppend(zRet, " %d", aiCol[i]);
+        }
+        zRet = fts5PrintfAppend(zRet, "} ");
+      }
+      if( zRet==0 ) return 0;
+    }
+
+    if( pNear->nPhrase>1 ){
+      zRet = fts5PrintfAppend(zRet, "-near %d ", pNear->nNear);
+      if( zRet==0 ) return 0;
+    }
+
+    zRet = fts5PrintfAppend(zRet, "--");
+    if( zRet==0 ) return 0;
+
+    for(i=0; i<pNear->nPhrase; i++){
+      Fts5ExprPhrase *pPhrase = pNear->apPhrase[i];
+
+      zRet = fts5PrintfAppend(zRet, " {");
+      for(iTerm=0; zRet && iTerm<pPhrase->nTerm; iTerm++){
+        char *zTerm = pPhrase->aTerm[iTerm].zTerm;
+        zRet = fts5PrintfAppend(zRet, "%s%s", iTerm==0?"":" ", zTerm);
+        if( pPhrase->aTerm[iTerm].bPrefix ){
+          zRet = fts5PrintfAppend(zRet, "*");
+        }
+      }
+
+      if( zRet ) zRet = fts5PrintfAppend(zRet, "}");
+      if( zRet==0 ) return 0;
+    }
+
+  }else{
+    char const *zOp = 0;
+    int i;
+    switch( pExpr->eType ){
+      case FTS5_AND: zOp = "AND"; break;
+      case FTS5_NOT: zOp = "NOT"; break;
+      default: 
+        assert( pExpr->eType==FTS5_OR );
+        zOp = "OR"; 
+        break;
+    }
+
+    zRet = sqlite3_mprintf("%s", zOp);
+    for(i=0; zRet && i<pExpr->nChild; i++){
+      char *z = fts5ExprPrintTcl(pConfig, zNearsetCmd, pExpr->apChild[i]);
+      if( !z ){
+        sqlite3_free(zRet);
+        zRet = 0;
+      }else{
+        zRet = fts5PrintfAppend(zRet, " [%z]", z);
+      }
+    }
+  }
+
+  return zRet;
+}
+
+static char *fts5ExprPrint(Fts5Config *pConfig, Fts5ExprNode *pExpr){
+  char *zRet = 0;
+  if( pExpr->eType==0 ){
+    return sqlite3_mprintf("\"\"");
+  }else
+  if( pExpr->eType==FTS5_STRING || pExpr->eType==FTS5_TERM ){
+    Fts5ExprNearset *pNear = pExpr->pNear;
+    int i; 
+    int iTerm;
+
+    if( pNear->pColset ){
+      int iCol = pNear->pColset->aiCol[0];
+      zRet = fts5PrintfAppend(zRet, "%s : ", pConfig->azCol[iCol]);
+      if( zRet==0 ) return 0;
+    }
+
+    if( pNear->nPhrase>1 ){
+      zRet = fts5PrintfAppend(zRet, "NEAR(");
+      if( zRet==0 ) return 0;
+    }
+
+    for(i=0; i<pNear->nPhrase; i++){
+      Fts5ExprPhrase *pPhrase = pNear->apPhrase[i];
+      if( i!=0 ){
+        zRet = fts5PrintfAppend(zRet, " ");
+        if( zRet==0 ) return 0;
+      }
+      for(iTerm=0; iTerm<pPhrase->nTerm; iTerm++){
+        char *zTerm = fts5ExprTermPrint(&pPhrase->aTerm[iTerm]);
+        if( zTerm ){
+          zRet = fts5PrintfAppend(zRet, "%s%s", iTerm==0?"":" + ", zTerm);
+          sqlite3_free(zTerm);
+        }
+        if( zTerm==0 || zRet==0 ){
+          sqlite3_free(zRet);
+          return 0;
+        }
+      }
+    }
+
+    if( pNear->nPhrase>1 ){
+      zRet = fts5PrintfAppend(zRet, ", %d)", pNear->nNear);
+      if( zRet==0 ) return 0;
+    }
+
+  }else{
+    char const *zOp = 0;
+    int i;
+
+    switch( pExpr->eType ){
+      case FTS5_AND: zOp = " AND "; break;
+      case FTS5_NOT: zOp = " NOT "; break;
+      default:  
+        assert( pExpr->eType==FTS5_OR );
+        zOp = " OR "; 
+        break;
+    }
+
+    for(i=0; i<pExpr->nChild; i++){
+      char *z = fts5ExprPrint(pConfig, pExpr->apChild[i]);
+      if( z==0 ){
+        sqlite3_free(zRet);
+        zRet = 0;
+      }else{
+        int e = pExpr->apChild[i]->eType;
+        int b = (e!=FTS5_STRING && e!=FTS5_TERM && e!=FTS5_EOF);
+        zRet = fts5PrintfAppend(zRet, "%s%s%z%s", 
+            (i==0 ? "" : zOp),
+            (b?"(":""), z, (b?")":"")
+        );
+      }
+      if( zRet==0 ) break;
+    }
+  }
+
+  return zRet;
+}
+
+/*
+** The implementation of user-defined scalar functions fts5_expr() (bTcl==0)
+** and fts5_expr_tcl() (bTcl!=0).
+*/
+static void fts5ExprFunction(
+  sqlite3_context *pCtx,          /* Function call context */
+  int nArg,                       /* Number of args */
+  sqlite3_value **apVal,          /* Function arguments */
+  int bTcl
+){
+  Fts5Global *pGlobal = (Fts5Global*)sqlite3_user_data(pCtx);
+  sqlite3 *db = sqlite3_context_db_handle(pCtx);
+  const char *zExpr = 0;
+  char *zErr = 0;
+  Fts5Expr *pExpr = 0;
+  int rc;
+  int i;
+
+  const char **azConfig;          /* Array of arguments for Fts5Config */
+  const char *zNearsetCmd = "nearset";
+  int nConfig;                    /* Size of azConfig[] */
+  Fts5Config *pConfig = 0;
+  int iArg = 1;
+
+  if( nArg<1 ){
+    zErr = sqlite3_mprintf("wrong number of arguments to function %s",
+        bTcl ? "fts5_expr_tcl" : "fts5_expr"
+    );
+    sqlite3_result_error(pCtx, zErr, -1);
+    sqlite3_free(zErr);
+    return;
+  }
+
+  if( bTcl && nArg>1 ){
+    zNearsetCmd = (const char*)sqlite3_value_text(apVal[1]);
+    iArg = 2;
+  }
+
+  nConfig = 3 + (nArg-iArg);
+  azConfig = (const char**)sqlite3_malloc(sizeof(char*) * nConfig);
+  if( azConfig==0 ){
+    sqlite3_result_error_nomem(pCtx);
+    return;
+  }
+  azConfig[0] = 0;
+  azConfig[1] = "main";
+  azConfig[2] = "tbl";
+  for(i=3; iArg<nArg; iArg++){
+    azConfig[i++] = (const char*)sqlite3_value_text(apVal[iArg]);
+  }
+
+  zExpr = (const char*)sqlite3_value_text(apVal[0]);
+
+  rc = sqlite3Fts5ConfigParse(pGlobal, db, nConfig, azConfig, &pConfig, &zErr);
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts5ExprNew(pConfig, zExpr, &pExpr, &zErr);
+  }
+  if( rc==SQLITE_OK ){
+    char *zText;
+    if( pExpr->pRoot->xNext==0 ){
+      zText = sqlite3_mprintf("");
+    }else if( bTcl ){
+      zText = fts5ExprPrintTcl(pConfig, zNearsetCmd, pExpr->pRoot);
+    }else{
+      zText = fts5ExprPrint(pConfig, pExpr->pRoot);
+    }
+    if( zText==0 ){
+      rc = SQLITE_NOMEM;
+    }else{
+      sqlite3_result_text(pCtx, zText, -1, SQLITE_TRANSIENT);
+      sqlite3_free(zText);
+    }
+  }
+
+  if( rc!=SQLITE_OK ){
+    if( zErr ){
+      sqlite3_result_error(pCtx, zErr, -1);
+      sqlite3_free(zErr);
+    }else{
+      sqlite3_result_error_code(pCtx, rc);
+    }
+  }
+  sqlite3_free((void *)azConfig);
+  sqlite3Fts5ConfigFree(pConfig);
+  sqlite3Fts5ExprFree(pExpr);
+}
+
+static void fts5ExprFunctionHr(
+  sqlite3_context *pCtx,          /* Function call context */
+  int nArg,                       /* Number of args */
+  sqlite3_value **apVal           /* Function arguments */
+){
+  fts5ExprFunction(pCtx, nArg, apVal, 0);
+}
+static void fts5ExprFunctionTcl(
+  sqlite3_context *pCtx,          /* Function call context */
+  int nArg,                       /* Number of args */
+  sqlite3_value **apVal           /* Function arguments */
+){
+  fts5ExprFunction(pCtx, nArg, apVal, 1);
+}
+
+/*
+** The implementation of an SQLite user-defined-function that accepts a
+** single integer as an argument. If the integer is an alpha-numeric 
+** unicode code point, 1 is returned. Otherwise 0.
+*/
+static void fts5ExprIsAlnum(
+  sqlite3_context *pCtx,          /* Function call context */
+  int nArg,                       /* Number of args */
+  sqlite3_value **apVal           /* Function arguments */
+){
+  int iCode;
+  if( nArg!=1 ){
+    sqlite3_result_error(pCtx, 
+        "wrong number of arguments to function fts5_isalnum", -1
+    );
+    return;
+  }
+  iCode = sqlite3_value_int(apVal[0]);
+  sqlite3_result_int(pCtx, sqlite3Fts5UnicodeIsalnum(iCode));
+}
+
+static void fts5ExprFold(
+  sqlite3_context *pCtx,          /* Function call context */
+  int nArg,                       /* Number of args */
+  sqlite3_value **apVal           /* Function arguments */
+){
+  if( nArg!=1 && nArg!=2 ){
+    sqlite3_result_error(pCtx, 
+        "wrong number of arguments to function fts5_fold", -1
+    );
+  }else{
+    int iCode;
+    int bRemoveDiacritics = 0;
+    iCode = sqlite3_value_int(apVal[0]);
+    if( nArg==2 ) bRemoveDiacritics = sqlite3_value_int(apVal[1]);
+    sqlite3_result_int(pCtx, sqlite3Fts5UnicodeFold(iCode, bRemoveDiacritics));
+  }
+}
+
+/*
+** This is called during initialization to register the fts5_expr() scalar
+** UDF with the SQLite handle passed as the only argument.
+*/
+static int sqlite3Fts5ExprInit(Fts5Global *pGlobal, sqlite3 *db){
+  struct Fts5ExprFunc {
+    const char *z;
+    void (*x)(sqlite3_context*,int,sqlite3_value**);
+  } aFunc[] = {
+    { "fts5_expr",     fts5ExprFunctionHr },
+    { "fts5_expr_tcl", fts5ExprFunctionTcl },
+    { "fts5_isalnum",  fts5ExprIsAlnum },
+    { "fts5_fold",     fts5ExprFold },
+  };
+  int i;
+  int rc = SQLITE_OK;
+  void *pCtx = (void*)pGlobal;
+
+  for(i=0; rc==SQLITE_OK && i<ArraySize(aFunc); i++){
+    struct Fts5ExprFunc *p = &aFunc[i];
+    rc = sqlite3_create_function(db, p->z, -1, SQLITE_UTF8, pCtx, p->x, 0, 0);
+  }
+
+  /* Avoid a warning indicating that sqlite3Fts5ParserTrace() is unused */
+#ifndef NDEBUG
+  (void)sqlite3Fts5ParserTrace;
+#endif
+
+  return rc;
+}
+
+/*
+** Return the number of phrases in expression pExpr.
+*/
+static int sqlite3Fts5ExprPhraseCount(Fts5Expr *pExpr){
+  return (pExpr ? pExpr->nPhrase : 0);
+}
+
+/*
+** Return the number of terms in the iPhrase'th phrase in pExpr.
+*/
+static int sqlite3Fts5ExprPhraseSize(Fts5Expr *pExpr, int iPhrase){
+  if( iPhrase<0 || iPhrase>=pExpr->nPhrase ) return 0;
+  return pExpr->apExprPhrase[iPhrase]->nTerm;
+}
+
+/*
+** This function is used to access the current position list for phrase
+** iPhrase.
+*/
+static int sqlite3Fts5ExprPoslist(Fts5Expr *pExpr, int iPhrase, const u8 **pa){
+  int nRet;
+  Fts5ExprPhrase *pPhrase = pExpr->apExprPhrase[iPhrase];
+  Fts5ExprNode *pNode = pPhrase->pNode;
+  if( pNode->bEof==0 && pNode->iRowid==pExpr->pRoot->iRowid ){
+    *pa = pPhrase->poslist.p;
+    nRet = pPhrase->poslist.n;
+  }else{
+    *pa = 0;
+    nRet = 0;
+  }
+  return nRet;
+}
+
+struct Fts5PoslistPopulator {
+  Fts5PoslistWriter writer;
+  int bOk;                        /* True if ok to populate */
+  int bMiss;
+};
+
+static Fts5PoslistPopulator *sqlite3Fts5ExprClearPoslists(Fts5Expr *pExpr, int bLive){
+  Fts5PoslistPopulator *pRet;
+  pRet = sqlite3_malloc(sizeof(Fts5PoslistPopulator)*pExpr->nPhrase);
+  if( pRet ){
+    int i;
+    memset(pRet, 0, sizeof(Fts5PoslistPopulator)*pExpr->nPhrase);
+    for(i=0; i<pExpr->nPhrase; i++){
+      Fts5Buffer *pBuf = &pExpr->apExprPhrase[i]->poslist;
+      Fts5ExprNode *pNode = pExpr->apExprPhrase[i]->pNode;
+      assert( pExpr->apExprPhrase[i]->nTerm==1 );
+      if( bLive && 
+          (pBuf->n==0 || pNode->iRowid!=pExpr->pRoot->iRowid || pNode->bEof)
+      ){
+        pRet[i].bMiss = 1;
+      }else{
+        pBuf->n = 0;
+      }
+    }
+  }
+  return pRet;
+}
+
+struct Fts5ExprCtx {
+  Fts5Expr *pExpr;
+  Fts5PoslistPopulator *aPopulator;
+  i64 iOff;
+};
+typedef struct Fts5ExprCtx Fts5ExprCtx;
+
+/*
+** TODO: Make this more efficient!
+*/
+static int fts5ExprColsetTest(Fts5Colset *pColset, int iCol){
+  int i;
+  for(i=0; i<pColset->nCol; i++){
+    if( pColset->aiCol[i]==iCol ) return 1;
+  }
+  return 0;
+}
+
+static int fts5ExprPopulatePoslistsCb(
+  void *pCtx,                /* Copy of 2nd argument to xTokenize() */
+  int tflags,                /* Mask of FTS5_TOKEN_* flags */
+  const char *pToken,        /* Pointer to buffer containing token */
+  int nToken,                /* Size of token in bytes */
+  int iUnused1,              /* Byte offset of token within input text */
+  int iUnused2               /* Byte offset of end of token within input text */
+){
+  Fts5ExprCtx *p = (Fts5ExprCtx*)pCtx;
+  Fts5Expr *pExpr = p->pExpr;
+  int i;
+
+  UNUSED_PARAM2(iUnused1, iUnused2);
+
+  if( nToken>FTS5_MAX_TOKEN_SIZE ) nToken = FTS5_MAX_TOKEN_SIZE;
+  if( (tflags & FTS5_TOKEN_COLOCATED)==0 ) p->iOff++;
+  for(i=0; i<pExpr->nPhrase; i++){
+    Fts5ExprTerm *pTerm;
+    if( p->aPopulator[i].bOk==0 ) continue;
+    for(pTerm=&pExpr->apExprPhrase[i]->aTerm[0]; pTerm; pTerm=pTerm->pSynonym){
+      int nTerm = (int)strlen(pTerm->zTerm);
+      if( (nTerm==nToken || (nTerm<nToken && pTerm->bPrefix))
+       && memcmp(pTerm->zTerm, pToken, nTerm)==0
+      ){
+        int rc = sqlite3Fts5PoslistWriterAppend(
+            &pExpr->apExprPhrase[i]->poslist, &p->aPopulator[i].writer, p->iOff
+        );
+        if( rc ) return rc;
+        break;
+      }
+    }
+  }
+  return SQLITE_OK;
+}
+
+static int sqlite3Fts5ExprPopulatePoslists(
+  Fts5Config *pConfig,
+  Fts5Expr *pExpr, 
+  Fts5PoslistPopulator *aPopulator,
+  int iCol, 
+  const char *z, int n
+){
+  int i;
+  Fts5ExprCtx sCtx;
+  sCtx.pExpr = pExpr;
+  sCtx.aPopulator = aPopulator;
+  sCtx.iOff = (((i64)iCol) << 32) - 1;
+
+  for(i=0; i<pExpr->nPhrase; i++){
+    Fts5ExprNode *pNode = pExpr->apExprPhrase[i]->pNode;
+    Fts5Colset *pColset = pNode->pNear->pColset;
+    if( (pColset && 0==fts5ExprColsetTest(pColset, iCol)) 
+     || aPopulator[i].bMiss
+    ){
+      aPopulator[i].bOk = 0;
+    }else{
+      aPopulator[i].bOk = 1;
+    }
+  }
+
+  return sqlite3Fts5Tokenize(pConfig, 
+      FTS5_TOKENIZE_DOCUMENT, z, n, (void*)&sCtx, fts5ExprPopulatePoslistsCb
+  );
+}
+
+static void fts5ExprClearPoslists(Fts5ExprNode *pNode){
+  if( pNode->eType==FTS5_TERM || pNode->eType==FTS5_STRING ){
+    pNode->pNear->apPhrase[0]->poslist.n = 0;
+  }else{
+    int i;
+    for(i=0; i<pNode->nChild; i++){
+      fts5ExprClearPoslists(pNode->apChild[i]);
+    }
+  }
+}
+
+static int fts5ExprCheckPoslists(Fts5ExprNode *pNode, i64 iRowid){
+  pNode->iRowid = iRowid;
+  pNode->bEof = 0;
+  switch( pNode->eType ){
+    case FTS5_TERM:
+    case FTS5_STRING:
+      return (pNode->pNear->apPhrase[0]->poslist.n>0);
+
+    case FTS5_AND: {
+      int i;
+      for(i=0; i<pNode->nChild; i++){
+        if( fts5ExprCheckPoslists(pNode->apChild[i], iRowid)==0 ){
+          fts5ExprClearPoslists(pNode);
+          return 0;
+        }
+      }
+      break;
+    }
+
+    case FTS5_OR: {
+      int i;
+      int bRet = 0;
+      for(i=0; i<pNode->nChild; i++){
+        if( fts5ExprCheckPoslists(pNode->apChild[i], iRowid) ){
+          bRet = 1;
+        }
+      }
+      return bRet;
+    }
+
+    default: {
+      assert( pNode->eType==FTS5_NOT );
+      if( 0==fts5ExprCheckPoslists(pNode->apChild[0], iRowid)
+          || 0!=fts5ExprCheckPoslists(pNode->apChild[1], iRowid)
+        ){
+        fts5ExprClearPoslists(pNode);
+        return 0;
+      }
+      break;
+    }
+  }
+  return 1;
+}
+
+static void sqlite3Fts5ExprCheckPoslists(Fts5Expr *pExpr, i64 iRowid){
+  fts5ExprCheckPoslists(pExpr->pRoot, iRowid);
+}
+
+/*
+** This function is only called for detail=columns tables. 
+*/
+static int sqlite3Fts5ExprPhraseCollist(
+  Fts5Expr *pExpr, 
+  int iPhrase, 
+  const u8 **ppCollist, 
+  int *pnCollist
+){
+  Fts5ExprPhrase *pPhrase = pExpr->apExprPhrase[iPhrase];
+  Fts5ExprNode *pNode = pPhrase->pNode;
+  int rc = SQLITE_OK;
+
+  assert( iPhrase>=0 && iPhrase<pExpr->nPhrase );
+  assert( pExpr->pConfig->eDetail==FTS5_DETAIL_COLUMNS );
+
+  if( pNode->bEof==0 
+   && pNode->iRowid==pExpr->pRoot->iRowid 
+   && pPhrase->poslist.n>0
+  ){
+    Fts5ExprTerm *pTerm = &pPhrase->aTerm[0];
+    if( pTerm->pSynonym ){
+      Fts5Buffer *pBuf = (Fts5Buffer*)&pTerm->pSynonym[1];
+      rc = fts5ExprSynonymList(
+          pTerm, pNode->iRowid, pBuf, (u8**)ppCollist, pnCollist
+      );
+    }else{
+      *ppCollist = pPhrase->aTerm[0].pIter->pData;
+      *pnCollist = pPhrase->aTerm[0].pIter->nData;
+    }
+  }else{
+    *ppCollist = 0;
+    *pnCollist = 0;
+  }
+
+  return rc;
+}
+
+
+/*
+** 2014 August 11
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+*/
+
+
+
+/* #include "fts5Int.h" */
+
+typedef struct Fts5HashEntry Fts5HashEntry;
+
+/*
+** This file contains the implementation of an in-memory hash table used
+** to accumuluate "term -> doclist" content before it is flused to a level-0
+** segment.
+*/
+
+
+struct Fts5Hash {
+  int eDetail;                    /* Copy of Fts5Config.eDetail */
+  int *pnByte;                    /* Pointer to bytes counter */
+  int nEntry;                     /* Number of entries currently in hash */
+  int nSlot;                      /* Size of aSlot[] array */
+  Fts5HashEntry *pScan;           /* Current ordered scan item */
+  Fts5HashEntry **aSlot;          /* Array of hash slots */
+};
+
+/*
+** Each entry in the hash table is represented by an object of the 
+** following type. Each object, its key (zKey[]) and its current data
+** are stored in a single memory allocation. The position list data 
+** immediately follows the key data in memory.
+**
+** The data that follows the key is in a similar, but not identical format
+** to the doclist data stored in the database. It is:
+**
+**   * Rowid, as a varint
+**   * Position list, without 0x00 terminator.
+**   * Size of previous position list and rowid, as a 4 byte
+**     big-endian integer.
+**
+** iRowidOff:
+**   Offset of last rowid written to data area. Relative to first byte of
+**   structure.
+**
+** nData:
+**   Bytes of data written since iRowidOff.
+*/
+struct Fts5HashEntry {
+  Fts5HashEntry *pHashNext;       /* Next hash entry with same hash-key */
+  Fts5HashEntry *pScanNext;       /* Next entry in sorted order */
+  
+  int nAlloc;                     /* Total size of allocation */
+  int iSzPoslist;                 /* Offset of space for 4-byte poslist size */
+  int nData;                      /* Total bytes of data (incl. structure) */
+  int nKey;                       /* Length of zKey[] in bytes */
+  u8 bDel;                        /* Set delete-flag @ iSzPoslist */
+  u8 bContent;                    /* Set content-flag (detail=none mode) */
+  i16 iCol;                       /* Column of last value written */
+  int iPos;                       /* Position of last value written */
+  i64 iRowid;                     /* Rowid of last value written */
+  char zKey[8];                   /* Nul-terminated entry key */
+};
+
+/*
+** Size of Fts5HashEntry without the zKey[] array.
+*/
+#define FTS5_HASHENTRYSIZE (sizeof(Fts5HashEntry)-8)
+
+
+
+/*
+** Allocate a new hash table.
+*/
+static int sqlite3Fts5HashNew(Fts5Config *pConfig, Fts5Hash **ppNew, int *pnByte){
+  int rc = SQLITE_OK;
+  Fts5Hash *pNew;
+
+  *ppNew = pNew = (Fts5Hash*)sqlite3_malloc(sizeof(Fts5Hash));
+  if( pNew==0 ){
+    rc = SQLITE_NOMEM;
+  }else{
+    int nByte;
+    memset(pNew, 0, sizeof(Fts5Hash));
+    pNew->pnByte = pnByte;
+    pNew->eDetail = pConfig->eDetail;
+
+    pNew->nSlot = 1024;
+    nByte = sizeof(Fts5HashEntry*) * pNew->nSlot;
+    pNew->aSlot = (Fts5HashEntry**)sqlite3_malloc(nByte);
+    if( pNew->aSlot==0 ){
+      sqlite3_free(pNew);
+      *ppNew = 0;
+      rc = SQLITE_NOMEM;
+    }else{
+      memset(pNew->aSlot, 0, nByte);
+    }
+  }
+  return rc;
+}
+
+/*
+** Free a hash table object.
+*/
+static void sqlite3Fts5HashFree(Fts5Hash *pHash){
+  if( pHash ){
+    sqlite3Fts5HashClear(pHash);
+    sqlite3_free(pHash->aSlot);
+    sqlite3_free(pHash);
+  }
+}
+
+/*
+** Empty (but do not delete) a hash table.
+*/
+static void sqlite3Fts5HashClear(Fts5Hash *pHash){
+  int i;
+  for(i=0; i<pHash->nSlot; i++){
+    Fts5HashEntry *pNext;
+    Fts5HashEntry *pSlot;
+    for(pSlot=pHash->aSlot[i]; pSlot; pSlot=pNext){
+      pNext = pSlot->pHashNext;
+      sqlite3_free(pSlot);
+    }
+  }
+  memset(pHash->aSlot, 0, pHash->nSlot * sizeof(Fts5HashEntry*));
+  pHash->nEntry = 0;
+}
+
+static unsigned int fts5HashKey(int nSlot, const u8 *p, int n){
+  int i;
+  unsigned int h = 13;
+  for(i=n-1; i>=0; i--){
+    h = (h << 3) ^ h ^ p[i];
+  }
+  return (h % nSlot);
+}
+
+static unsigned int fts5HashKey2(int nSlot, u8 b, const u8 *p, int n){
+  int i;
+  unsigned int h = 13;
+  for(i=n-1; i>=0; i--){
+    h = (h << 3) ^ h ^ p[i];
+  }
+  h = (h << 3) ^ h ^ b;
+  return (h % nSlot);
+}
+
+/*
+** Resize the hash table by doubling the number of slots.
+*/
+static int fts5HashResize(Fts5Hash *pHash){
+  int nNew = pHash->nSlot*2;
+  int i;
+  Fts5HashEntry **apNew;
+  Fts5HashEntry **apOld = pHash->aSlot;
+
+  apNew = (Fts5HashEntry**)sqlite3_malloc(nNew*sizeof(Fts5HashEntry*));
+  if( !apNew ) return SQLITE_NOMEM;
+  memset(apNew, 0, nNew*sizeof(Fts5HashEntry*));
+
+  for(i=0; i<pHash->nSlot; i++){
+    while( apOld[i] ){
+      int iHash;
+      Fts5HashEntry *p = apOld[i];
+      apOld[i] = p->pHashNext;
+      iHash = fts5HashKey(nNew, (u8*)p->zKey, (int)strlen(p->zKey));
+      p->pHashNext = apNew[iHash];
+      apNew[iHash] = p;
+    }
+  }
+
+  sqlite3_free(apOld);
+  pHash->nSlot = nNew;
+  pHash->aSlot = apNew;
+  return SQLITE_OK;
+}
+
+static void fts5HashAddPoslistSize(Fts5Hash *pHash, Fts5HashEntry *p){
+  if( p->iSzPoslist ){
+    u8 *pPtr = (u8*)p;
+    if( pHash->eDetail==FTS5_DETAIL_NONE ){
+      assert( p->nData==p->iSzPoslist );
+      if( p->bDel ){
+        pPtr[p->nData++] = 0x00;
+        if( p->bContent ){
+          pPtr[p->nData++] = 0x00;
+        }
+      }
+    }else{
+      int nSz = (p->nData - p->iSzPoslist - 1);       /* Size in bytes */
+      int nPos = nSz*2 + p->bDel;                     /* Value of nPos field */
+
+      assert( p->bDel==0 || p->bDel==1 );
+      if( nPos<=127 ){
+        pPtr[p->iSzPoslist] = (u8)nPos;
+      }else{
+        int nByte = sqlite3Fts5GetVarintLen((u32)nPos);
+        memmove(&pPtr[p->iSzPoslist + nByte], &pPtr[p->iSzPoslist + 1], nSz);
+        sqlite3Fts5PutVarint(&pPtr[p->iSzPoslist], nPos);
+        p->nData += (nByte-1);
+      }
+    }
+
+    p->iSzPoslist = 0;
+    p->bDel = 0;
+    p->bContent = 0;
+  }
+}
+
+/*
+** Add an entry to the in-memory hash table. The key is the concatenation
+** of bByte and (pToken/nToken). The value is (iRowid/iCol/iPos).
+**
+**     (bByte || pToken) -> (iRowid,iCol,iPos)
+**
+** Or, if iCol is negative, then the value is a delete marker.
+*/
+static int sqlite3Fts5HashWrite(
+  Fts5Hash *pHash,
+  i64 iRowid,                     /* Rowid for this entry */
+  int iCol,                       /* Column token appears in (-ve -> delete) */
+  int iPos,                       /* Position of token within column */
+  char bByte,                     /* First byte of token */
+  const char *pToken, int nToken  /* Token to add or remove to or from index */
+){
+  unsigned int iHash;
+  Fts5HashEntry *p;
+  u8 *pPtr;
+  int nIncr = 0;                  /* Amount to increment (*pHash->pnByte) by */
+  int bNew;                       /* If non-delete entry should be written */
+  
+  bNew = (pHash->eDetail==FTS5_DETAIL_FULL);
+
+  /* Attempt to locate an existing hash entry */
+  iHash = fts5HashKey2(pHash->nSlot, (u8)bByte, (const u8*)pToken, nToken);
+  for(p=pHash->aSlot[iHash]; p; p=p->pHashNext){
+    if( p->zKey[0]==bByte 
+     && p->nKey==nToken
+     && memcmp(&p->zKey[1], pToken, nToken)==0 
+    ){
+      break;
+    }
+  }
+
+  /* If an existing hash entry cannot be found, create a new one. */
+  if( p==0 ){
+    /* Figure out how much space to allocate */
+    int nByte = FTS5_HASHENTRYSIZE + (nToken+1) + 1 + 64;
+    if( nByte<128 ) nByte = 128;
+
+    /* Grow the Fts5Hash.aSlot[] array if necessary. */
+    if( (pHash->nEntry*2)>=pHash->nSlot ){
+      int rc = fts5HashResize(pHash);
+      if( rc!=SQLITE_OK ) return rc;
+      iHash = fts5HashKey2(pHash->nSlot, (u8)bByte, (const u8*)pToken, nToken);
+    }
+
+    /* Allocate new Fts5HashEntry and add it to the hash table. */
+    p = (Fts5HashEntry*)sqlite3_malloc(nByte);
+    if( !p ) return SQLITE_NOMEM;
+    memset(p, 0, FTS5_HASHENTRYSIZE);
+    p->nAlloc = nByte;
+    p->zKey[0] = bByte;
+    memcpy(&p->zKey[1], pToken, nToken);
+    assert( iHash==fts5HashKey(pHash->nSlot, (u8*)p->zKey, nToken+1) );
+    p->nKey = nToken;
+    p->zKey[nToken+1] = '\0';
+    p->nData = nToken+1 + 1 + FTS5_HASHENTRYSIZE;
+    p->pHashNext = pHash->aSlot[iHash];
+    pHash->aSlot[iHash] = p;
+    pHash->nEntry++;
+
+    /* Add the first rowid field to the hash-entry */
+    p->nData += sqlite3Fts5PutVarint(&((u8*)p)[p->nData], iRowid);
+    p->iRowid = iRowid;
+
+    p->iSzPoslist = p->nData;
+    if( pHash->eDetail!=FTS5_DETAIL_NONE ){
+      p->nData += 1;
+      p->iCol = (pHash->eDetail==FTS5_DETAIL_FULL ? 0 : -1);
+    }
+
+    nIncr += p->nData;
+  }else{
+
+    /* Appending to an existing hash-entry. Check that there is enough 
+    ** space to append the largest possible new entry. Worst case scenario 
+    ** is:
+    **
+    **     + 9 bytes for a new rowid,
+    **     + 4 byte reserved for the "poslist size" varint.
+    **     + 1 byte for a "new column" byte,
+    **     + 3 bytes for a new column number (16-bit max) as a varint,
+    **     + 5 bytes for the new position offset (32-bit max).
+    */
+    if( (p->nAlloc - p->nData) < (9 + 4 + 1 + 3 + 5) ){
+      int nNew = p->nAlloc * 2;
+      Fts5HashEntry *pNew;
+      Fts5HashEntry **pp;
+      pNew = (Fts5HashEntry*)sqlite3_realloc(p, nNew);
+      if( pNew==0 ) return SQLITE_NOMEM;
+      pNew->nAlloc = nNew;
+      for(pp=&pHash->aSlot[iHash]; *pp!=p; pp=&(*pp)->pHashNext);
+      *pp = pNew;
+      p = pNew;
+    }
+    nIncr -= p->nData;
+  }
+  assert( (p->nAlloc - p->nData) >= (9 + 4 + 1 + 3 + 5) );
+
+  pPtr = (u8*)p;
+
+  /* If this is a new rowid, append the 4-byte size field for the previous
+  ** entry, and the new rowid for this entry.  */
+  if( iRowid!=p->iRowid ){
+    fts5HashAddPoslistSize(pHash, p);
+    p->nData += sqlite3Fts5PutVarint(&pPtr[p->nData], iRowid - p->iRowid);
+    p->iRowid = iRowid;
+    bNew = 1;
+    p->iSzPoslist = p->nData;
+    if( pHash->eDetail!=FTS5_DETAIL_NONE ){
+      p->nData += 1;
+      p->iCol = (pHash->eDetail==FTS5_DETAIL_FULL ? 0 : -1);
+      p->iPos = 0;
+    }
+  }
+
+  if( iCol>=0 ){
+    if( pHash->eDetail==FTS5_DETAIL_NONE ){
+      p->bContent = 1;
+    }else{
+      /* Append a new column value, if necessary */
+      assert( iCol>=p->iCol );
+      if( iCol!=p->iCol ){
+        if( pHash->eDetail==FTS5_DETAIL_FULL ){
+          pPtr[p->nData++] = 0x01;
+          p->nData += sqlite3Fts5PutVarint(&pPtr[p->nData], iCol);
+          p->iCol = (i16)iCol;
+          p->iPos = 0;
+        }else{
+          bNew = 1;
+          p->iCol = (i16)(iPos = iCol);
+        }
+      }
+
+      /* Append the new position offset, if necessary */
+      if( bNew ){
+        p->nData += sqlite3Fts5PutVarint(&pPtr[p->nData], iPos - p->iPos + 2);
+        p->iPos = iPos;
+      }
+    }
+  }else{
+    /* This is a delete. Set the delete flag. */
+    p->bDel = 1;
+  }
+
+  nIncr += p->nData;
+  *pHash->pnByte += nIncr;
+  return SQLITE_OK;
+}
+
+
+/*
+** Arguments pLeft and pRight point to linked-lists of hash-entry objects,
+** each sorted in key order. This function merges the two lists into a
+** single list and returns a pointer to its first element.
+*/
+static Fts5HashEntry *fts5HashEntryMerge(
+  Fts5HashEntry *pLeft,
+  Fts5HashEntry *pRight
+){
+  Fts5HashEntry *p1 = pLeft;
+  Fts5HashEntry *p2 = pRight;
+  Fts5HashEntry *pRet = 0;
+  Fts5HashEntry **ppOut = &pRet;
+
+  while( p1 || p2 ){
+    if( p1==0 ){
+      *ppOut = p2;
+      p2 = 0;
+    }else if( p2==0 ){
+      *ppOut = p1;
+      p1 = 0;
+    }else{
+      int i = 0;
+      while( p1->zKey[i]==p2->zKey[i] ) i++;
+
+      if( ((u8)p1->zKey[i])>((u8)p2->zKey[i]) ){
+        /* p2 is smaller */
+        *ppOut = p2;
+        ppOut = &p2->pScanNext;
+        p2 = p2->pScanNext;
+      }else{
+        /* p1 is smaller */
+        *ppOut = p1;
+        ppOut = &p1->pScanNext;
+        p1 = p1->pScanNext;
+      }
+      *ppOut = 0;
+    }
+  }
+
+  return pRet;
+}
+
+/*
+** Extract all tokens from hash table iHash and link them into a list
+** in sorted order. The hash table is cleared before returning. It is
+** the responsibility of the caller to free the elements of the returned
+** list.
+*/
+static int fts5HashEntrySort(
+  Fts5Hash *pHash, 
+  const char *pTerm, int nTerm,   /* Query prefix, if any */
+  Fts5HashEntry **ppSorted
+){
+  const int nMergeSlot = 32;
+  Fts5HashEntry **ap;
+  Fts5HashEntry *pList;
+  int iSlot;
+  int i;
+
+  *ppSorted = 0;
+  ap = sqlite3_malloc(sizeof(Fts5HashEntry*) * nMergeSlot);
+  if( !ap ) return SQLITE_NOMEM;
+  memset(ap, 0, sizeof(Fts5HashEntry*) * nMergeSlot);
+
+  for(iSlot=0; iSlot<pHash->nSlot; iSlot++){
+    Fts5HashEntry *pIter;
+    for(pIter=pHash->aSlot[iSlot]; pIter; pIter=pIter->pHashNext){
+      if( pTerm==0 || 0==memcmp(pIter->zKey, pTerm, nTerm) ){
+        Fts5HashEntry *pEntry = pIter;
+        pEntry->pScanNext = 0;
+        for(i=0; ap[i]; i++){
+          pEntry = fts5HashEntryMerge(pEntry, ap[i]);
+          ap[i] = 0;
+        }
+        ap[i] = pEntry;
+      }
+    }
+  }
+
+  pList = 0;
+  for(i=0; i<nMergeSlot; i++){
+    pList = fts5HashEntryMerge(pList, ap[i]);
+  }
+
+  pHash->nEntry = 0;
+  sqlite3_free(ap);
+  *ppSorted = pList;
+  return SQLITE_OK;
+}
+
+/*
+** Query the hash table for a doclist associated with term pTerm/nTerm.
+*/
+static int sqlite3Fts5HashQuery(
+  Fts5Hash *pHash,                /* Hash table to query */
+  const char *pTerm, int nTerm,   /* Query term */
+  const u8 **ppDoclist,           /* OUT: Pointer to doclist for pTerm */
+  int *pnDoclist                  /* OUT: Size of doclist in bytes */
+){
+  unsigned int iHash = fts5HashKey(pHash->nSlot, (const u8*)pTerm, nTerm);
+  Fts5HashEntry *p;
+
+  for(p=pHash->aSlot[iHash]; p; p=p->pHashNext){
+    if( memcmp(p->zKey, pTerm, nTerm)==0 && p->zKey[nTerm]==0 ) break;
+  }
+
+  if( p ){
+    fts5HashAddPoslistSize(pHash, p);
+    *ppDoclist = (const u8*)&p->zKey[nTerm+1];
+    *pnDoclist = p->nData - (FTS5_HASHENTRYSIZE + nTerm + 1);
+  }else{
+    *ppDoclist = 0;
+    *pnDoclist = 0;
+  }
+
+  return SQLITE_OK;
+}
+
+static int sqlite3Fts5HashScanInit(
+  Fts5Hash *p,                    /* Hash table to query */
+  const char *pTerm, int nTerm    /* Query prefix */
+){
+  return fts5HashEntrySort(p, pTerm, nTerm, &p->pScan);
+}
+
+static void sqlite3Fts5HashScanNext(Fts5Hash *p){
+  assert( !sqlite3Fts5HashScanEof(p) );
+  p->pScan = p->pScan->pScanNext;
+}
+
+static int sqlite3Fts5HashScanEof(Fts5Hash *p){
+  return (p->pScan==0);
+}
+
+static void sqlite3Fts5HashScanEntry(
+  Fts5Hash *pHash,
+  const char **pzTerm,            /* OUT: term (nul-terminated) */
+  const u8 **ppDoclist,           /* OUT: pointer to doclist */
+  int *pnDoclist                  /* OUT: size of doclist in bytes */
+){
+  Fts5HashEntry *p;
+  if( (p = pHash->pScan) ){
+    int nTerm = (int)strlen(p->zKey);
+    fts5HashAddPoslistSize(pHash, p);
+    *pzTerm = p->zKey;
+    *ppDoclist = (const u8*)&p->zKey[nTerm+1];
+    *pnDoclist = p->nData - (FTS5_HASHENTRYSIZE + nTerm + 1);
+  }else{
+    *pzTerm = 0;
+    *ppDoclist = 0;
+    *pnDoclist = 0;
+  }
+}
+
+
+/*
+** 2014 May 31
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** Low level access to the FTS index stored in the database file. The 
+** routines in this file file implement all read and write access to the
+** %_data table. Other parts of the system access this functionality via
+** the interface defined in fts5Int.h.
+*/
+
+
+/* #include "fts5Int.h" */
+
+/*
+** Overview:
+**
+** The %_data table contains all the FTS indexes for an FTS5 virtual table.
+** As well as the main term index, there may be up to 31 prefix indexes.
+** The format is similar to FTS3/4, except that:
+**
+**   * all segment b-tree leaf data is stored in fixed size page records 
+**     (e.g. 1000 bytes). A single doclist may span multiple pages. Care is 
+**     taken to ensure it is possible to iterate in either direction through 
+**     the entries in a doclist, or to seek to a specific entry within a 
+**     doclist, without loading it into memory.
+**
+**   * large doclists that span many pages have associated "doclist index"
+**     records that contain a copy of the first rowid on each page spanned by
+**     the doclist. This is used to speed up seek operations, and merges of
+**     large doclists with very small doclists.
+**
+**   * extra fields in the "structure record" record the state of ongoing
+**     incremental merge operations.
+**
+*/
+
+
+#define FTS5_OPT_WORK_UNIT  1000  /* Number of leaf pages per optimize step */
+#define FTS5_WORK_UNIT      64    /* Number of leaf pages in unit of work */
+
+#define FTS5_MIN_DLIDX_SIZE 4     /* Add dlidx if this many empty pages */
+
+#define FTS5_MAIN_PREFIX '0'
+
+#if FTS5_MAX_PREFIX_INDEXES > 31
+# error "FTS5_MAX_PREFIX_INDEXES is too large"
+#endif
+
+/*
+** Details:
+**
+** The %_data table managed by this module,
+**
+**     CREATE TABLE %_data(id INTEGER PRIMARY KEY, block BLOB);
+**
+** , contains the following 5 types of records. See the comments surrounding
+** the FTS5_*_ROWID macros below for a description of how %_data rowids are 
+** assigned to each fo them.
+**
+** 1. Structure Records:
+**
+**   The set of segments that make up an index - the index structure - are
+**   recorded in a single record within the %_data table. The record consists
+**   of a single 32-bit configuration cookie value followed by a list of 
+**   SQLite varints. If the FTS table features more than one index (because
+**   there are one or more prefix indexes), it is guaranteed that all share
+**   the same cookie value.
+**
+**   Immediately following the configuration cookie, the record begins with
+**   three varints:
+**
+**     + number of levels,
+**     + total number of segments on all levels,
+**     + value of write counter.
+**
+**   Then, for each level from 0 to nMax:
+**
+**     + number of input segments in ongoing merge.
+**     + total number of segments in level.
+**     + for each segment from oldest to newest:
+**         + segment id (always > 0)
+**         + first leaf page number (often 1, always greater than 0)
+**         + final leaf page number
+**
+** 2. The Averages Record:
+**
+**   A single record within the %_data table. The data is a list of varints.
+**   The first value is the number of rows in the index. Then, for each column
+**   from left to right, the total number of tokens in the column for all
+**   rows of the table.
+**
+** 3. Segment leaves:
+**
+**   TERM/DOCLIST FORMAT:
+**
+**     Most of each segment leaf is taken up by term/doclist data. The 
+**     general format of term/doclist, starting with the first term
+**     on the leaf page, is:
+**
+**         varint : size of first term
+**         blob:    first term data
+**         doclist: first doclist
+**         zero-or-more {
+**           varint:  number of bytes in common with previous term
+**           varint:  number of bytes of new term data (nNew)
+**           blob:    nNew bytes of new term data
+**           doclist: next doclist
+**         }
+**
+**     doclist format:
+**
+**         varint:  first rowid
+**         poslist: first poslist
+**         zero-or-more {
+**           varint:  rowid delta (always > 0)
+**           poslist: next poslist
+**         }
+**
+**     poslist format:
+**
+**         varint: size of poslist in bytes multiplied by 2, not including
+**                 this field. Plus 1 if this entry carries the "delete" flag.
+**         collist: collist for column 0
+**         zero-or-more {
+**           0x01 byte
+**           varint: column number (I)
+**           collist: collist for column I
+**         }
+**
+**     collist format:
+**
+**         varint: first offset + 2
+**         zero-or-more {
+**           varint: offset delta + 2
+**         }
+**
+**   PAGE FORMAT
+**
+**     Each leaf page begins with a 4-byte header containing 2 16-bit 
+**     unsigned integer fields in big-endian format. They are:
+**
+**       * The byte offset of the first rowid on the page, if it exists
+**         and occurs before the first term (otherwise 0).
+**
+**       * The byte offset of the start of the page footer. If the page
+**         footer is 0 bytes in size, then this field is the same as the
+**         size of the leaf page in bytes.
+**
+**     The page footer consists of a single varint for each term located
+**     on the page. Each varint is the byte offset of the current term
+**     within the page, delta-compressed against the previous value. In
+**     other words, the first varint in the footer is the byte offset of
+**     the first term, the second is the byte offset of the second less that
+**     of the first, and so on.
+**
+**     The term/doclist format described above is accurate if the entire
+**     term/doclist data fits on a single leaf page. If this is not the case,
+**     the format is changed in two ways:
+**
+**       + if the first rowid on a page occurs before the first term, it
+**         is stored as a literal value:
+**
+**             varint:  first rowid
+**
+**       + the first term on each page is stored in the same way as the
+**         very first term of the segment:
+**
+**             varint : size of first term
+**             blob:    first term data
+**
+** 5. Segment doclist indexes:
+**
+**   Doclist indexes are themselves b-trees, however they usually consist of
+**   a single leaf record only. The format of each doclist index leaf page 
+**   is:
+**
+**     * Flags byte. Bits are:
+**         0x01: Clear if leaf is also the root page, otherwise set.
+**
+**     * Page number of fts index leaf page. As a varint.
+**
+**     * First rowid on page indicated by previous field. As a varint.
+**
+**     * A list of varints, one for each subsequent termless page. A 
+**       positive delta if the termless page contains at least one rowid, 
+**       or an 0x00 byte otherwise.
+**
+**   Internal doclist index nodes are:
+**
+**     * Flags byte. Bits are:
+**         0x01: Clear for root page, otherwise set.
+**
+**     * Page number of first child page. As a varint.
+**
+**     * Copy of first rowid on page indicated by previous field. As a varint.
+**
+**     * A list of delta-encoded varints - the first rowid on each subsequent
+**       child page. 
+**
+*/
+
+/*
+** Rowids for the averages and structure records in the %_data table.
+*/
+#define FTS5_AVERAGES_ROWID     1    /* Rowid used for the averages record */
+#define FTS5_STRUCTURE_ROWID   10    /* The structure record */
+
+/*
+** Macros determining the rowids used by segment leaves and dlidx leaves
+** and nodes. All nodes and leaves are stored in the %_data table with large
+** positive rowids.
+**
+** Each segment has a unique non-zero 16-bit id.
+**
+** The rowid for each segment leaf is found by passing the segment id and 
+** the leaf page number to the FTS5_SEGMENT_ROWID macro. Leaves are numbered
+** sequentially starting from 1.
+*/
+#define FTS5_DATA_ID_B     16     /* Max seg id number 65535 */
+#define FTS5_DATA_DLI_B     1     /* Doclist-index flag (1 bit) */
+#define FTS5_DATA_HEIGHT_B  5     /* Max dlidx tree height of 32 */
+#define FTS5_DATA_PAGE_B   31     /* Max page number of 2147483648 */
+
+#define fts5_dri(segid, dlidx, height, pgno) (                                 \
+ ((i64)(segid)  << (FTS5_DATA_PAGE_B+FTS5_DATA_HEIGHT_B+FTS5_DATA_DLI_B)) +    \
+ ((i64)(dlidx)  << (FTS5_DATA_PAGE_B + FTS5_DATA_HEIGHT_B)) +                  \
+ ((i64)(height) << (FTS5_DATA_PAGE_B)) +                                       \
+ ((i64)(pgno))                                                                 \
+)
+
+#define FTS5_SEGMENT_ROWID(segid, pgno)       fts5_dri(segid, 0, 0, pgno)
+#define FTS5_DLIDX_ROWID(segid, height, pgno) fts5_dri(segid, 1, height, pgno)
+
+/*
+** Maximum segments permitted in a single index 
+*/
+#define FTS5_MAX_SEGMENT 2000
+
+#ifdef SQLITE_DEBUG
+static int sqlite3Fts5Corrupt() { return SQLITE_CORRUPT_VTAB; }
+#endif
+
+
+/*
+** Each time a blob is read from the %_data table, it is padded with this
+** many zero bytes. This makes it easier to decode the various record formats
+** without overreading if the records are corrupt.
+*/
+#define FTS5_DATA_ZERO_PADDING 8
+#define FTS5_DATA_PADDING 20
+
+typedef struct Fts5Data Fts5Data;
+typedef struct Fts5DlidxIter Fts5DlidxIter;
+typedef struct Fts5DlidxLvl Fts5DlidxLvl;
+typedef struct Fts5DlidxWriter Fts5DlidxWriter;
+typedef struct Fts5Iter Fts5Iter;
+typedef struct Fts5PageWriter Fts5PageWriter;
+typedef struct Fts5SegIter Fts5SegIter;
+typedef struct Fts5DoclistIter Fts5DoclistIter;
+typedef struct Fts5SegWriter Fts5SegWriter;
+typedef struct Fts5Structure Fts5Structure;
+typedef struct Fts5StructureLevel Fts5StructureLevel;
+typedef struct Fts5StructureSegment Fts5StructureSegment;
+
+struct Fts5Data {
+  u8 *p;                          /* Pointer to buffer containing record */
+  int nn;                         /* Size of record in bytes */
+  int szLeaf;                     /* Size of leaf without page-index */
+};
+
+/*
+** One object per %_data table.
+*/
+struct Fts5Index {
+  Fts5Config *pConfig;            /* Virtual table configuration */
+  char *zDataTbl;                 /* Name of %_data table */
+  int nWorkUnit;                  /* Leaf pages in a "unit" of work */
+
+  /*
+  ** Variables related to the accumulation of tokens and doclists within the
+  ** in-memory hash tables before they are flushed to disk.
+  */
+  Fts5Hash *pHash;                /* Hash table for in-memory data */
+  int nPendingData;               /* Current bytes of pending data */
+  i64 iWriteRowid;                /* Rowid for current doc being written */
+  int bDelete;                    /* Current write is a delete */
+
+  /* Error state. */
+  int rc;                         /* Current error code */
+
+  /* State used by the fts5DataXXX() functions. */
+  sqlite3_blob *pReader;          /* RO incr-blob open on %_data table */
+  sqlite3_stmt *pWriter;          /* "INSERT ... %_data VALUES(?,?)" */
+  sqlite3_stmt *pDeleter;         /* "DELETE FROM %_data ... id>=? AND id<=?" */
+  sqlite3_stmt *pIdxWriter;       /* "INSERT ... %_idx VALUES(?,?,?,?)" */
+  sqlite3_stmt *pIdxDeleter;      /* "DELETE FROM %_idx WHERE segid=? */
+  sqlite3_stmt *pIdxSelect;
+  int nRead;                      /* Total number of blocks read */
+
+  sqlite3_stmt *pDataVersion;
+  i64 iStructVersion;             /* data_version when pStruct read */
+  Fts5Structure *pStruct;         /* Current db structure (or NULL) */
+};
+
+struct Fts5DoclistIter {
+  u8 *aEof;                       /* Pointer to 1 byte past end of doclist */
+
+  /* Output variables. aPoslist==0 at EOF */
+  i64 iRowid;
+  u8 *aPoslist;
+  int nPoslist;
+  int nSize;
+};
+
+/*
+** The contents of the "structure" record for each index are represented
+** using an Fts5Structure record in memory. Which uses instances of the 
+** other Fts5StructureXXX types as components.
+*/
+struct Fts5StructureSegment {
+  int iSegid;                     /* Segment id */
+  int pgnoFirst;                  /* First leaf page number in segment */
+  int pgnoLast;                   /* Last leaf page number in segment */
+};
+struct Fts5StructureLevel {
+  int nMerge;                     /* Number of segments in incr-merge */
+  int nSeg;                       /* Total number of segments on level */
+  Fts5StructureSegment *aSeg;     /* Array of segments. aSeg[0] is oldest. */
+};
+struct Fts5Structure {
+  int nRef;                       /* Object reference count */
+  u64 nWriteCounter;              /* Total leaves written to level 0 */
+  int nSegment;                   /* Total segments in this structure */
+  int nLevel;                     /* Number of levels in this index */
+  Fts5StructureLevel aLevel[1];   /* Array of nLevel level objects */
+};
+
+/*
+** An object of type Fts5SegWriter is used to write to segments.
+*/
+struct Fts5PageWriter {
+  int pgno;                       /* Page number for this page */
+  int iPrevPgidx;                 /* Previous value written into pgidx */
+  Fts5Buffer buf;                 /* Buffer containing leaf data */
+  Fts5Buffer pgidx;               /* Buffer containing page-index */
+  Fts5Buffer term;                /* Buffer containing previous term on page */
+};
+struct Fts5DlidxWriter {
+  int pgno;                       /* Page number for this page */
+  int bPrevValid;                 /* True if iPrev is valid */
+  i64 iPrev;                      /* Previous rowid value written to page */
+  Fts5Buffer buf;                 /* Buffer containing page data */
+};
+struct Fts5SegWriter {
+  int iSegid;                     /* Segid to write to */
+  Fts5PageWriter writer;          /* PageWriter object */
+  i64 iPrevRowid;                 /* Previous rowid written to current leaf */
+  u8 bFirstRowidInDoclist;        /* True if next rowid is first in doclist */
+  u8 bFirstRowidInPage;           /* True if next rowid is first in page */
+  /* TODO1: Can use (writer.pgidx.n==0) instead of bFirstTermInPage */
+  u8 bFirstTermInPage;            /* True if next term will be first in leaf */
+  int nLeafWritten;               /* Number of leaf pages written */
+  int nEmpty;                     /* Number of contiguous term-less nodes */
+
+  int nDlidx;                     /* Allocated size of aDlidx[] array */
+  Fts5DlidxWriter *aDlidx;        /* Array of Fts5DlidxWriter objects */
+
+  /* Values to insert into the %_idx table */
+  Fts5Buffer btterm;              /* Next term to insert into %_idx table */
+  int iBtPage;                    /* Page number corresponding to btterm */
+};
+
+typedef struct Fts5CResult Fts5CResult;
+struct Fts5CResult {
+  u16 iFirst;                     /* aSeg[] index of firstest iterator */
+  u8 bTermEq;                     /* True if the terms are equal */
+};
+
+/*
+** Object for iterating through a single segment, visiting each term/rowid
+** pair in the segment.
+**
+** pSeg:
+**   The segment to iterate through.
+**
+** iLeafPgno:
+**   Current leaf page number within segment.
+**
+** iLeafOffset:
+**   Byte offset within the current leaf that is the first byte of the 
+**   position list data (one byte passed the position-list size field).
+**   rowid field of the current entry. Usually this is the size field of the
+**   position list data. The exception is if the rowid for the current entry 
+**   is the last thing on the leaf page.
+**
+** pLeaf:
+**   Buffer containing current leaf page data. Set to NULL at EOF.
+**
+** iTermLeafPgno, iTermLeafOffset:
+**   Leaf page number containing the last term read from the segment. And
+**   the offset immediately following the term data.
+**
+** flags:
+**   Mask of FTS5_SEGITER_XXX values. Interpreted as follows:
+**
+**   FTS5_SEGITER_ONETERM:
+**     If set, set the iterator to point to EOF after the current doclist 
+**     has been exhausted. Do not proceed to the next term in the segment.
+**
+**   FTS5_SEGITER_REVERSE:
+**     This flag is only ever set if FTS5_SEGITER_ONETERM is also set. If
+**     it is set, iterate through rowid in descending order instead of the
+**     default ascending order.
+**
+** iRowidOffset/nRowidOffset/aRowidOffset:
+**     These are used if the FTS5_SEGITER_REVERSE flag is set.
+**
+**     For each rowid on the page corresponding to the current term, the
+**     corresponding aRowidOffset[] entry is set to the byte offset of the
+**     start of the "position-list-size" field within the page.
+**
+** iTermIdx:
+**     Index of current term on iTermLeafPgno.
+*/
+struct Fts5SegIter {
+  Fts5StructureSegment *pSeg;     /* Segment to iterate through */
+  int flags;                      /* Mask of configuration flags */
+  int iLeafPgno;                  /* Current leaf page number */
+  Fts5Data *pLeaf;                /* Current leaf data */
+  Fts5Data *pNextLeaf;            /* Leaf page (iLeafPgno+1) */
+  int iLeafOffset;                /* Byte offset within current leaf */
+
+  /* Next method */
+  void (*xNext)(Fts5Index*, Fts5SegIter*, int*);
+
+  /* The page and offset from which the current term was read. The offset 
+  ** is the offset of the first rowid in the current doclist.  */
+  int iTermLeafPgno;
+  int iTermLeafOffset;
+
+  int iPgidxOff;                  /* Next offset in pgidx */
+  int iEndofDoclist;
+
+  /* The following are only used if the FTS5_SEGITER_REVERSE flag is set. */
+  int iRowidOffset;               /* Current entry in aRowidOffset[] */
+  int nRowidOffset;               /* Allocated size of aRowidOffset[] array */
+  int *aRowidOffset;              /* Array of offset to rowid fields */
+
+  Fts5DlidxIter *pDlidx;          /* If there is a doclist-index */
+
+  /* Variables populated based on current entry. */
+  Fts5Buffer term;                /* Current term */
+  i64 iRowid;                     /* Current rowid */
+  int nPos;                       /* Number of bytes in current position list */
+  u8 bDel;                        /* True if the delete flag is set */
+};
+
+/*
+** Argument is a pointer to an Fts5Data structure that contains a 
+** leaf page.
+*/
+#define ASSERT_SZLEAF_OK(x) assert( \
+    (x)->szLeaf==(x)->nn || (x)->szLeaf==fts5GetU16(&(x)->p[2]) \
+)
+
+#define FTS5_SEGITER_ONETERM 0x01
+#define FTS5_SEGITER_REVERSE 0x02
+
+/* 
+** Argument is a pointer to an Fts5Data structure that contains a leaf
+** page. This macro evaluates to true if the leaf contains no terms, or
+** false if it contains at least one term.
+*/
+#define fts5LeafIsTermless(x) ((x)->szLeaf >= (x)->nn)
+
+#define fts5LeafTermOff(x, i) (fts5GetU16(&(x)->p[(x)->szLeaf + (i)*2]))
+
+#define fts5LeafFirstRowidOff(x) (fts5GetU16((x)->p))
+
+/*
+** Object for iterating through the merged results of one or more segments,
+** visiting each term/rowid pair in the merged data.
+**
+** nSeg is always a power of two greater than or equal to the number of
+** segments that this object is merging data from. Both the aSeg[] and
+** aFirst[] arrays are sized at nSeg entries. The aSeg[] array is padded
+** with zeroed objects - these are handled as if they were iterators opened
+** on empty segments.
+**
+** The results of comparing segments aSeg[N] and aSeg[N+1], where N is an
+** even number, is stored in aFirst[(nSeg+N)/2]. The "result" of the 
+** comparison in this context is the index of the iterator that currently
+** points to the smaller term/rowid combination. Iterators at EOF are
+** considered to be greater than all other iterators.
+**
+** aFirst[1] contains the index in aSeg[] of the iterator that points to
+** the smallest key overall. aFirst[0] is unused. 
+**
+** poslist:
+**   Used by sqlite3Fts5IterPoslist() when the poslist needs to be buffered.
+**   There is no way to tell if this is populated or not.
+*/
+struct Fts5Iter {
+  Fts5IndexIter base;             /* Base class containing output vars */
+
+  Fts5Index *pIndex;              /* Index that owns this iterator */
+  Fts5Structure *pStruct;         /* Database structure for this iterator */
+  Fts5Buffer poslist;             /* Buffer containing current poslist */
+  Fts5Colset *pColset;            /* Restrict matches to these columns */
+
+  /* Invoked to set output variables. */
+  void (*xSetOutputs)(Fts5Iter*, Fts5SegIter*);
+
+  int nSeg;                       /* Size of aSeg[] array */
+  int bRev;                       /* True to iterate in reverse order */
+  u8 bSkipEmpty;                  /* True to skip deleted entries */
+
+  i64 iSwitchRowid;               /* Firstest rowid of other than aFirst[1] */
+  Fts5CResult *aFirst;            /* Current merge state (see above) */
+  Fts5SegIter aSeg[1];            /* Array of segment iterators */
+};
+
+
+/*
+** An instance of the following type is used to iterate through the contents
+** of a doclist-index record.
+**
+** pData:
+**   Record containing the doclist-index data.
+**
+** bEof:
+**   Set to true once iterator has reached EOF.
+**
+** iOff:
+**   Set to the current offset within record pData.
+*/
+struct Fts5DlidxLvl {
+  Fts5Data *pData;              /* Data for current page of this level */
+  int iOff;                     /* Current offset into pData */
+  int bEof;                     /* At EOF already */
+  int iFirstOff;                /* Used by reverse iterators */
+
+  /* Output variables */
+  int iLeafPgno;                /* Page number of current leaf page */
+  i64 iRowid;                   /* First rowid on leaf iLeafPgno */
+};
+struct Fts5DlidxIter {
+  int nLvl;
+  int iSegid;
+  Fts5DlidxLvl aLvl[1];
+};
+
+static void fts5PutU16(u8 *aOut, u16 iVal){
+  aOut[0] = (iVal>>8);
+  aOut[1] = (iVal&0xFF);
+}
+
+static u16 fts5GetU16(const u8 *aIn){
+  return ((u16)aIn[0] << 8) + aIn[1];
+} 
+
+/*
+** Allocate and return a buffer at least nByte bytes in size.
+**
+** If an OOM error is encountered, return NULL and set the error code in
+** the Fts5Index handle passed as the first argument.
+*/
+static void *fts5IdxMalloc(Fts5Index *p, int nByte){
+  return sqlite3Fts5MallocZero(&p->rc, nByte);
+}
+
+/*
+** Compare the contents of the pLeft buffer with the pRight/nRight blob.
+**
+** Return -ve if pLeft is smaller than pRight, 0 if they are equal or
+** +ve if pRight is smaller than pLeft. In other words:
+**
+**     res = *pLeft - *pRight
+*/
+#ifdef SQLITE_DEBUG
+static int fts5BufferCompareBlob(
+  Fts5Buffer *pLeft,              /* Left hand side of comparison */
+  const u8 *pRight, int nRight    /* Right hand side of comparison */
+){
+  int nCmp = MIN(pLeft->n, nRight);
+  int res = memcmp(pLeft->p, pRight, nCmp);
+  return (res==0 ? (pLeft->n - nRight) : res);
+}
+#endif
+
+/*
+** Compare the contents of the two buffers using memcmp(). If one buffer
+** is a prefix of the other, it is considered the lesser.
+**
+** Return -ve if pLeft is smaller than pRight, 0 if they are equal or
+** +ve if pRight is smaller than pLeft. In other words:
+**
+**     res = *pLeft - *pRight
+*/
+static int fts5BufferCompare(Fts5Buffer *pLeft, Fts5Buffer *pRight){
+  int nCmp = MIN(pLeft->n, pRight->n);
+  int res = memcmp(pLeft->p, pRight->p, nCmp);
+  return (res==0 ? (pLeft->n - pRight->n) : res);
+}
+
+static int fts5LeafFirstTermOff(Fts5Data *pLeaf){
+  int ret;
+  fts5GetVarint32(&pLeaf->p[pLeaf->szLeaf], ret);
+  return ret;
+}
+
+/*
+** Close the read-only blob handle, if it is open.
+*/
+static void fts5CloseReader(Fts5Index *p){
+  if( p->pReader ){
+    sqlite3_blob *pReader = p->pReader;
+    p->pReader = 0;
+    sqlite3_blob_close(pReader);
+  }
+}
+
+
+/*
+** Retrieve a record from the %_data table.
+**
+** If an error occurs, NULL is returned and an error left in the 
+** Fts5Index object.
+*/
+static Fts5Data *fts5DataRead(Fts5Index *p, i64 iRowid){
+  Fts5Data *pRet = 0;
+  if( p->rc==SQLITE_OK ){
+    int rc = SQLITE_OK;
+
+    if( p->pReader ){
+      /* This call may return SQLITE_ABORT if there has been a savepoint
+      ** rollback since it was last used. In this case a new blob handle
+      ** is required.  */
+      sqlite3_blob *pBlob = p->pReader;
+      p->pReader = 0;
+      rc = sqlite3_blob_reopen(pBlob, iRowid);
+      assert( p->pReader==0 );
+      p->pReader = pBlob;
+      if( rc!=SQLITE_OK ){
+        fts5CloseReader(p);
+      }
+      if( rc==SQLITE_ABORT ) rc = SQLITE_OK;
+    }
+
+    /* If the blob handle is not open at this point, open it and seek 
+    ** to the requested entry.  */
+    if( p->pReader==0 && rc==SQLITE_OK ){
+      Fts5Config *pConfig = p->pConfig;
+      rc = sqlite3_blob_open(pConfig->db, 
+          pConfig->zDb, p->zDataTbl, "block", iRowid, 0, &p->pReader
+      );
+    }
+
+    /* If either of the sqlite3_blob_open() or sqlite3_blob_reopen() calls
+    ** above returned SQLITE_ERROR, return SQLITE_CORRUPT_VTAB instead.
+    ** All the reasons those functions might return SQLITE_ERROR - missing
+    ** table, missing row, non-blob/text in block column - indicate 
+    ** backing store corruption.  */
+    if( rc==SQLITE_ERROR ) rc = FTS5_CORRUPT;
+
+    if( rc==SQLITE_OK ){
+      u8 *aOut = 0;               /* Read blob data into this buffer */
+      int nByte = sqlite3_blob_bytes(p->pReader);
+      int nAlloc = sizeof(Fts5Data) + nByte + FTS5_DATA_PADDING;
+      pRet = (Fts5Data*)sqlite3_malloc(nAlloc);
+      if( pRet ){
+        pRet->nn = nByte;
+        aOut = pRet->p = (u8*)&pRet[1];
+      }else{
+        rc = SQLITE_NOMEM;
+      }
+
+      if( rc==SQLITE_OK ){
+        rc = sqlite3_blob_read(p->pReader, aOut, nByte, 0);
+      }
+      if( rc!=SQLITE_OK ){
+        sqlite3_free(pRet);
+        pRet = 0;
+      }else{
+        /* TODO1: Fix this */
+        pRet->szLeaf = fts5GetU16(&pRet->p[2]);
+      }
+    }
+    p->rc = rc;
+    p->nRead++;
+  }
+
+  assert( (pRet==0)==(p->rc!=SQLITE_OK) );
+  return pRet;
+}
+
+/*
+** Release a reference to data record returned by an earlier call to
+** fts5DataRead().
+*/
+static void fts5DataRelease(Fts5Data *pData){
+  sqlite3_free(pData);
+}
+
+static Fts5Data *fts5LeafRead(Fts5Index *p, i64 iRowid){
+  Fts5Data *pRet = fts5DataRead(p, iRowid);
+  if( pRet ){
+    if( pRet->szLeaf>pRet->nn ){
+      p->rc = FTS5_CORRUPT;
+      fts5DataRelease(pRet);
+      pRet = 0;
+    }
+  }
+  return pRet;
+}
+
+static int fts5IndexPrepareStmt(
+  Fts5Index *p,
+  sqlite3_stmt **ppStmt,
+  char *zSql
+){
+  if( p->rc==SQLITE_OK ){
+    if( zSql ){
+      p->rc = sqlite3_prepare_v2(p->pConfig->db, zSql, -1, ppStmt, 0);
+    }else{
+      p->rc = SQLITE_NOMEM;
+    }
+  }
+  sqlite3_free(zSql);
+  return p->rc;
+}
+
+
+/*
+** INSERT OR REPLACE a record into the %_data table.
+*/
+static void fts5DataWrite(Fts5Index *p, i64 iRowid, const u8 *pData, int nData){
+  if( p->rc!=SQLITE_OK ) return;
+
+  if( p->pWriter==0 ){
+    Fts5Config *pConfig = p->pConfig;
+    fts5IndexPrepareStmt(p, &p->pWriter, sqlite3_mprintf(
+          "REPLACE INTO '%q'.'%q_data'(id, block) VALUES(?,?)", 
+          pConfig->zDb, pConfig->zName
+    ));
+    if( p->rc ) return;
+  }
+
+  sqlite3_bind_int64(p->pWriter, 1, iRowid);
+  sqlite3_bind_blob(p->pWriter, 2, pData, nData, SQLITE_STATIC);
+  sqlite3_step(p->pWriter);
+  p->rc = sqlite3_reset(p->pWriter);
+}
+
+/*
+** Execute the following SQL:
+**
+**     DELETE FROM %_data WHERE id BETWEEN $iFirst AND $iLast
+*/
+static void fts5DataDelete(Fts5Index *p, i64 iFirst, i64 iLast){
+  if( p->rc!=SQLITE_OK ) return;
+
+  if( p->pDeleter==0 ){
+    int rc;
+    Fts5Config *pConfig = p->pConfig;
+    char *zSql = sqlite3_mprintf(
+        "DELETE FROM '%q'.'%q_data' WHERE id>=? AND id<=?", 
+          pConfig->zDb, pConfig->zName
+    );
+    if( zSql==0 ){
+      rc = SQLITE_NOMEM;
+    }else{
+      rc = sqlite3_prepare_v2(pConfig->db, zSql, -1, &p->pDeleter, 0);
+      sqlite3_free(zSql);
+    }
+    if( rc!=SQLITE_OK ){
+      p->rc = rc;
+      return;
+    }
+  }
+
+  sqlite3_bind_int64(p->pDeleter, 1, iFirst);
+  sqlite3_bind_int64(p->pDeleter, 2, iLast);
+  sqlite3_step(p->pDeleter);
+  p->rc = sqlite3_reset(p->pDeleter);
+}
+
+/*
+** Remove all records associated with segment iSegid.
+*/
+static void fts5DataRemoveSegment(Fts5Index *p, int iSegid){
+  i64 iFirst = FTS5_SEGMENT_ROWID(iSegid, 0);
+  i64 iLast = FTS5_SEGMENT_ROWID(iSegid+1, 0)-1;
+  fts5DataDelete(p, iFirst, iLast);
+  if( p->pIdxDeleter==0 ){
+    Fts5Config *pConfig = p->pConfig;
+    fts5IndexPrepareStmt(p, &p->pIdxDeleter, sqlite3_mprintf(
+          "DELETE FROM '%q'.'%q_idx' WHERE segid=?",
+          pConfig->zDb, pConfig->zName
+    ));
+  }
+  if( p->rc==SQLITE_OK ){
+    sqlite3_bind_int(p->pIdxDeleter, 1, iSegid);
+    sqlite3_step(p->pIdxDeleter);
+    p->rc = sqlite3_reset(p->pIdxDeleter);
+  }
+}
+
+/*
+** Release a reference to an Fts5Structure object returned by an earlier 
+** call to fts5StructureRead() or fts5StructureDecode().
+*/
+static void fts5StructureRelease(Fts5Structure *pStruct){
+  if( pStruct && 0>=(--pStruct->nRef) ){
+    int i;
+    assert( pStruct->nRef==0 );
+    for(i=0; i<pStruct->nLevel; i++){
+      sqlite3_free(pStruct->aLevel[i].aSeg);
+    }
+    sqlite3_free(pStruct);
+  }
+}
+
+static void fts5StructureRef(Fts5Structure *pStruct){
+  pStruct->nRef++;
+}
+
+/*
+** Deserialize and return the structure record currently stored in serialized
+** form within buffer pData/nData.
+**
+** The Fts5Structure.aLevel[] and each Fts5StructureLevel.aSeg[] array
+** are over-allocated by one slot. This allows the structure contents
+** to be more easily edited.
+**
+** If an error occurs, *ppOut is set to NULL and an SQLite error code
+** returned. Otherwise, *ppOut is set to point to the new object and
+** SQLITE_OK returned.
+*/
+static int fts5StructureDecode(
+  const u8 *pData,                /* Buffer containing serialized structure */
+  int nData,                      /* Size of buffer pData in bytes */
+  int *piCookie,                  /* Configuration cookie value */
+  Fts5Structure **ppOut           /* OUT: Deserialized object */
+){
+  int rc = SQLITE_OK;
+  int i = 0;
+  int iLvl;
+  int nLevel = 0;
+  int nSegment = 0;
+  int nByte;                      /* Bytes of space to allocate at pRet */
+  Fts5Structure *pRet = 0;        /* Structure object to return */
+
+  /* Grab the cookie value */
+  if( piCookie ) *piCookie = sqlite3Fts5Get32(pData);
+  i = 4;
+
+  /* Read the total number of levels and segments from the start of the
+  ** structure record.  */
+  i += fts5GetVarint32(&pData[i], nLevel);
+  i += fts5GetVarint32(&pData[i], nSegment);
+  nByte = (
+      sizeof(Fts5Structure) +                    /* Main structure */
+      sizeof(Fts5StructureLevel) * (nLevel-1)    /* aLevel[] array */
+  );
+  pRet = (Fts5Structure*)sqlite3Fts5MallocZero(&rc, nByte);
+
+  if( pRet ){
+    pRet->nRef = 1;
+    pRet->nLevel = nLevel;
+    pRet->nSegment = nSegment;
+    i += sqlite3Fts5GetVarint(&pData[i], &pRet->nWriteCounter);
+
+    for(iLvl=0; rc==SQLITE_OK && iLvl<nLevel; iLvl++){
+      Fts5StructureLevel *pLvl = &pRet->aLevel[iLvl];
+      int nTotal = 0;
+      int iSeg;
+
+      if( i>=nData ){
+        rc = FTS5_CORRUPT;
+      }else{
+        i += fts5GetVarint32(&pData[i], pLvl->nMerge);
+        i += fts5GetVarint32(&pData[i], nTotal);
+        assert( nTotal>=pLvl->nMerge );
+        pLvl->aSeg = (Fts5StructureSegment*)sqlite3Fts5MallocZero(&rc, 
+            nTotal * sizeof(Fts5StructureSegment)
+        );
+      }
+
+      if( rc==SQLITE_OK ){
+        pLvl->nSeg = nTotal;
+        for(iSeg=0; iSeg<nTotal; iSeg++){
+          if( i>=nData ){
+            rc = FTS5_CORRUPT;
+            break;
+          }
+          i += fts5GetVarint32(&pData[i], pLvl->aSeg[iSeg].iSegid);
+          i += fts5GetVarint32(&pData[i], pLvl->aSeg[iSeg].pgnoFirst);
+          i += fts5GetVarint32(&pData[i], pLvl->aSeg[iSeg].pgnoLast);
+        }
+      }
+    }
+    if( rc!=SQLITE_OK ){
+      fts5StructureRelease(pRet);
+      pRet = 0;
+    }
+  }
+
+  *ppOut = pRet;
+  return rc;
+}
+
+/*
+**
+*/
+static void fts5StructureAddLevel(int *pRc, Fts5Structure **ppStruct){
+  if( *pRc==SQLITE_OK ){
+    Fts5Structure *pStruct = *ppStruct;
+    int nLevel = pStruct->nLevel;
+    int nByte = (
+        sizeof(Fts5Structure) +                  /* Main structure */
+        sizeof(Fts5StructureLevel) * (nLevel+1)  /* aLevel[] array */
+    );
+
+    pStruct = sqlite3_realloc(pStruct, nByte);
+    if( pStruct ){
+      memset(&pStruct->aLevel[nLevel], 0, sizeof(Fts5StructureLevel));
+      pStruct->nLevel++;
+      *ppStruct = pStruct;
+    }else{
+      *pRc = SQLITE_NOMEM;
+    }
+  }
+}
+
+/*
+** Extend level iLvl so that there is room for at least nExtra more
+** segments.
+*/
+static void fts5StructureExtendLevel(
+  int *pRc, 
+  Fts5Structure *pStruct, 
+  int iLvl, 
+  int nExtra, 
+  int bInsert
+){
+  if( *pRc==SQLITE_OK ){
+    Fts5StructureLevel *pLvl = &pStruct->aLevel[iLvl];
+    Fts5StructureSegment *aNew;
+    int nByte;
+
+    nByte = (pLvl->nSeg + nExtra) * sizeof(Fts5StructureSegment);
+    aNew = sqlite3_realloc(pLvl->aSeg, nByte);
+    if( aNew ){
+      if( bInsert==0 ){
+        memset(&aNew[pLvl->nSeg], 0, sizeof(Fts5StructureSegment) * nExtra);
+      }else{
+        int nMove = pLvl->nSeg * sizeof(Fts5StructureSegment);
+        memmove(&aNew[nExtra], aNew, nMove);
+        memset(aNew, 0, sizeof(Fts5StructureSegment) * nExtra);
+      }
+      pLvl->aSeg = aNew;
+    }else{
+      *pRc = SQLITE_NOMEM;
+    }
+  }
+}
+
+static Fts5Structure *fts5StructureReadUncached(Fts5Index *p){
+  Fts5Structure *pRet = 0;
+  Fts5Config *pConfig = p->pConfig;
+  int iCookie;                    /* Configuration cookie */
+  Fts5Data *pData;
+
+  pData = fts5DataRead(p, FTS5_STRUCTURE_ROWID);
+  if( p->rc==SQLITE_OK ){
+    /* TODO: Do we need this if the leaf-index is appended? Probably... */
+    memset(&pData->p[pData->nn], 0, FTS5_DATA_PADDING);
+    p->rc = fts5StructureDecode(pData->p, pData->nn, &iCookie, &pRet);
+    if( p->rc==SQLITE_OK && pConfig->iCookie!=iCookie ){
+      p->rc = sqlite3Fts5ConfigLoad(pConfig, iCookie);
+    }
+    fts5DataRelease(pData);
+    if( p->rc!=SQLITE_OK ){
+      fts5StructureRelease(pRet);
+      pRet = 0;
+    }
+  }
+
+  return pRet;
+}
+
+static i64 fts5IndexDataVersion(Fts5Index *p){
+  i64 iVersion = 0;
+
+  if( p->rc==SQLITE_OK ){
+    if( p->pDataVersion==0 ){
+      p->rc = fts5IndexPrepareStmt(p, &p->pDataVersion, 
+          sqlite3_mprintf("PRAGMA %Q.data_version", p->pConfig->zDb)
+          );
+      if( p->rc ) return 0;
+    }
+
+    if( SQLITE_ROW==sqlite3_step(p->pDataVersion) ){
+      iVersion = sqlite3_column_int64(p->pDataVersion, 0);
+    }
+    p->rc = sqlite3_reset(p->pDataVersion);
+  }
+
+  return iVersion;
+}
+
+/*
+** Read, deserialize and return the structure record.
+**
+** The Fts5Structure.aLevel[] and each Fts5StructureLevel.aSeg[] array
+** are over-allocated as described for function fts5StructureDecode() 
+** above.
+**
+** If an error occurs, NULL is returned and an error code left in the
+** Fts5Index handle. If an error has already occurred when this function
+** is called, it is a no-op.
+*/
+static Fts5Structure *fts5StructureRead(Fts5Index *p){
+
+  if( p->pStruct==0 ){
+    p->iStructVersion = fts5IndexDataVersion(p);
+    if( p->rc==SQLITE_OK ){
+      p->pStruct = fts5StructureReadUncached(p);
+    }
+  }
+
+#if 0
+  else{
+    Fts5Structure *pTest = fts5StructureReadUncached(p);
+    if( pTest ){
+      int i, j;
+      assert_nc( p->pStruct->nSegment==pTest->nSegment );
+      assert_nc( p->pStruct->nLevel==pTest->nLevel );
+      for(i=0; i<pTest->nLevel; i++){
+        assert_nc( p->pStruct->aLevel[i].nMerge==pTest->aLevel[i].nMerge );
+        assert_nc( p->pStruct->aLevel[i].nSeg==pTest->aLevel[i].nSeg );
+        for(j=0; j<pTest->aLevel[i].nSeg; j++){
+          Fts5StructureSegment *p1 = &pTest->aLevel[i].aSeg[j];
+          Fts5StructureSegment *p2 = &p->pStruct->aLevel[i].aSeg[j];
+          assert_nc( p1->iSegid==p2->iSegid );
+          assert_nc( p1->pgnoFirst==p2->pgnoFirst );
+          assert_nc( p1->pgnoLast==p2->pgnoLast );
+        }
+      }
+      fts5StructureRelease(pTest);
+    }
+  }
+#endif
+
+  if( p->rc!=SQLITE_OK ) return 0;
+  assert( p->iStructVersion!=0 );
+  assert( p->pStruct!=0 );
+  fts5StructureRef(p->pStruct);
+  return p->pStruct;
+}
+
+static void fts5StructureInvalidate(Fts5Index *p){
+  if( p->pStruct ){
+    fts5StructureRelease(p->pStruct);
+    p->pStruct = 0;
+  }
+}
+
+/*
+** Return the total number of segments in index structure pStruct. This
+** function is only ever used as part of assert() conditions.
+*/
+#ifdef SQLITE_DEBUG
+static int fts5StructureCountSegments(Fts5Structure *pStruct){
+  int nSegment = 0;               /* Total number of segments */
+  if( pStruct ){
+    int iLvl;                     /* Used to iterate through levels */
+    for(iLvl=0; iLvl<pStruct->nLevel; iLvl++){
+      nSegment += pStruct->aLevel[iLvl].nSeg;
+    }
+  }
+
+  return nSegment;
+}
+#endif
+
+#define fts5BufferSafeAppendBlob(pBuf, pBlob, nBlob) {     \
+  assert( (pBuf)->nSpace>=((pBuf)->n+nBlob) );             \
+  memcpy(&(pBuf)->p[(pBuf)->n], pBlob, nBlob);             \
+  (pBuf)->n += nBlob;                                      \
+}
+
+#define fts5BufferSafeAppendVarint(pBuf, iVal) {                \
+  (pBuf)->n += sqlite3Fts5PutVarint(&(pBuf)->p[(pBuf)->n], (iVal));  \
+  assert( (pBuf)->nSpace>=(pBuf)->n );                          \
+}
+
+
+/*
+** Serialize and store the "structure" record.
+**
+** If an error occurs, leave an error code in the Fts5Index object. If an
+** error has already occurred, this function is a no-op.
+*/
+static void fts5StructureWrite(Fts5Index *p, Fts5Structure *pStruct){
+  if( p->rc==SQLITE_OK ){
+    Fts5Buffer buf;               /* Buffer to serialize record into */
+    int iLvl;                     /* Used to iterate through levels */
+    int iCookie;                  /* Cookie value to store */
+
+    assert( pStruct->nSegment==fts5StructureCountSegments(pStruct) );
+    memset(&buf, 0, sizeof(Fts5Buffer));
+
+    /* Append the current configuration cookie */
+    iCookie = p->pConfig->iCookie;
+    if( iCookie<0 ) iCookie = 0;
+
+    if( 0==sqlite3Fts5BufferSize(&p->rc, &buf, 4+9+9+9) ){
+      sqlite3Fts5Put32(buf.p, iCookie);
+      buf.n = 4;
+      fts5BufferSafeAppendVarint(&buf, pStruct->nLevel);
+      fts5BufferSafeAppendVarint(&buf, pStruct->nSegment);
+      fts5BufferSafeAppendVarint(&buf, (i64)pStruct->nWriteCounter);
+    }
+
+    for(iLvl=0; iLvl<pStruct->nLevel; iLvl++){
+      int iSeg;                     /* Used to iterate through segments */
+      Fts5StructureLevel *pLvl = &pStruct->aLevel[iLvl];
+      fts5BufferAppendVarint(&p->rc, &buf, pLvl->nMerge);
+      fts5BufferAppendVarint(&p->rc, &buf, pLvl->nSeg);
+      assert( pLvl->nMerge<=pLvl->nSeg );
+
+      for(iSeg=0; iSeg<pLvl->nSeg; iSeg++){
+        fts5BufferAppendVarint(&p->rc, &buf, pLvl->aSeg[iSeg].iSegid);
+        fts5BufferAppendVarint(&p->rc, &buf, pLvl->aSeg[iSeg].pgnoFirst);
+        fts5BufferAppendVarint(&p->rc, &buf, pLvl->aSeg[iSeg].pgnoLast);
+      }
+    }
+
+    fts5DataWrite(p, FTS5_STRUCTURE_ROWID, buf.p, buf.n);
+    fts5BufferFree(&buf);
+  }
+}
+
+#if 0
+static void fts5DebugStructure(int*,Fts5Buffer*,Fts5Structure*);
+static void fts5PrintStructure(const char *zCaption, Fts5Structure *pStruct){
+  int rc = SQLITE_OK;
+  Fts5Buffer buf;
+  memset(&buf, 0, sizeof(buf));
+  fts5DebugStructure(&rc, &buf, pStruct);
+  fprintf(stdout, "%s: %s\n", zCaption, buf.p);
+  fflush(stdout);
+  fts5BufferFree(&buf);
+}
+#else
+# define fts5PrintStructure(x,y)
+#endif
+
+static int fts5SegmentSize(Fts5StructureSegment *pSeg){
+  return 1 + pSeg->pgnoLast - pSeg->pgnoFirst;
+}
+
+/*
+** Return a copy of index structure pStruct. Except, promote as many 
+** segments as possible to level iPromote. If an OOM occurs, NULL is 
+** returned.
+*/
+static void fts5StructurePromoteTo(
+  Fts5Index *p,
+  int iPromote,
+  int szPromote,
+  Fts5Structure *pStruct
+){
+  int il, is;
+  Fts5StructureLevel *pOut = &pStruct->aLevel[iPromote];
+
+  if( pOut->nMerge==0 ){
+    for(il=iPromote+1; il<pStruct->nLevel; il++){
+      Fts5StructureLevel *pLvl = &pStruct->aLevel[il];
+      if( pLvl->nMerge ) return;
+      for(is=pLvl->nSeg-1; is>=0; is--){
+        int sz = fts5SegmentSize(&pLvl->aSeg[is]);
+        if( sz>szPromote ) return;
+        fts5StructureExtendLevel(&p->rc, pStruct, iPromote, 1, 1);
+        if( p->rc ) return;
+        memcpy(pOut->aSeg, &pLvl->aSeg[is], sizeof(Fts5StructureSegment));
+        pOut->nSeg++;
+        pLvl->nSeg--;
+      }
+    }
+  }
+}
+
+/*
+** A new segment has just been written to level iLvl of index structure
+** pStruct. This function determines if any segments should be promoted
+** as a result. Segments are promoted in two scenarios:
+**
+**   a) If the segment just written is smaller than one or more segments
+**      within the previous populated level, it is promoted to the previous
+**      populated level.
+**
+**   b) If the segment just written is larger than the newest segment on
+**      the next populated level, then that segment, and any other adjacent
+**      segments that are also smaller than the one just written, are 
+**      promoted. 
+**
+** If one or more segments are promoted, the structure object is updated
+** to reflect this.
+*/
+static void fts5StructurePromote(
+  Fts5Index *p,                   /* FTS5 backend object */
+  int iLvl,                       /* Index level just updated */
+  Fts5Structure *pStruct          /* Index structure */
+){
+  if( p->rc==SQLITE_OK ){
+    int iTst;
+    int iPromote = -1;
+    int szPromote = 0;            /* Promote anything this size or smaller */
+    Fts5StructureSegment *pSeg;   /* Segment just written */
+    int szSeg;                    /* Size of segment just written */
+    int nSeg = pStruct->aLevel[iLvl].nSeg;
+
+    if( nSeg==0 ) return;
+    pSeg = &pStruct->aLevel[iLvl].aSeg[pStruct->aLevel[iLvl].nSeg-1];
+    szSeg = (1 + pSeg->pgnoLast - pSeg->pgnoFirst);
+
+    /* Check for condition (a) */
+    for(iTst=iLvl-1; iTst>=0 && pStruct->aLevel[iTst].nSeg==0; iTst--);
+    if( iTst>=0 ){
+      int i;
+      int szMax = 0;
+      Fts5StructureLevel *pTst = &pStruct->aLevel[iTst];
+      assert( pTst->nMerge==0 );
+      for(i=0; i<pTst->nSeg; i++){
+        int sz = pTst->aSeg[i].pgnoLast - pTst->aSeg[i].pgnoFirst + 1;
+        if( sz>szMax ) szMax = sz;
+      }
+      if( szMax>=szSeg ){
+        /* Condition (a) is true. Promote the newest segment on level 
+        ** iLvl to level iTst.  */
+        iPromote = iTst;
+        szPromote = szMax;
+      }
+    }
+
+    /* If condition (a) is not met, assume (b) is true. StructurePromoteTo()
+    ** is a no-op if it is not.  */
+    if( iPromote<0 ){
+      iPromote = iLvl;
+      szPromote = szSeg;
+    }
+    fts5StructurePromoteTo(p, iPromote, szPromote, pStruct);
+  }
+}
+
+
+/*
+** Advance the iterator passed as the only argument. If the end of the 
+** doclist-index page is reached, return non-zero.
+*/
+static int fts5DlidxLvlNext(Fts5DlidxLvl *pLvl){
+  Fts5Data *pData = pLvl->pData;
+
+  if( pLvl->iOff==0 ){
+    assert( pLvl->bEof==0 );
+    pLvl->iOff = 1;
+    pLvl->iOff += fts5GetVarint32(&pData->p[1], pLvl->iLeafPgno);
+    pLvl->iOff += fts5GetVarint(&pData->p[pLvl->iOff], (u64*)&pLvl->iRowid);
+    pLvl->iFirstOff = pLvl->iOff;
+  }else{
+    int iOff;
+    for(iOff=pLvl->iOff; iOff<pData->nn; iOff++){
+      if( pData->p[iOff] ) break; 
+    }
+
+    if( iOff<pData->nn ){
+      i64 iVal;
+      pLvl->iLeafPgno += (iOff - pLvl->iOff) + 1;
+      iOff += fts5GetVarint(&pData->p[iOff], (u64*)&iVal);
+      pLvl->iRowid += iVal;
+      pLvl->iOff = iOff;
+    }else{
+      pLvl->bEof = 1;
+    }
+  }
+
+  return pLvl->bEof;
+}
+
+/*
+** Advance the iterator passed as the only argument.
+*/
+static int fts5DlidxIterNextR(Fts5Index *p, Fts5DlidxIter *pIter, int iLvl){
+  Fts5DlidxLvl *pLvl = &pIter->aLvl[iLvl];
+
+  assert( iLvl<pIter->nLvl );
+  if( fts5DlidxLvlNext(pLvl) ){
+    if( (iLvl+1) < pIter->nLvl ){
+      fts5DlidxIterNextR(p, pIter, iLvl+1);
+      if( pLvl[1].bEof==0 ){
+        fts5DataRelease(pLvl->pData);
+        memset(pLvl, 0, sizeof(Fts5DlidxLvl));
+        pLvl->pData = fts5DataRead(p, 
+            FTS5_DLIDX_ROWID(pIter->iSegid, iLvl, pLvl[1].iLeafPgno)
+        );
+        if( pLvl->pData ) fts5DlidxLvlNext(pLvl);
+      }
+    }
+  }
+
+  return pIter->aLvl[0].bEof;
+}
+static int fts5DlidxIterNext(Fts5Index *p, Fts5DlidxIter *pIter){
+  return fts5DlidxIterNextR(p, pIter, 0);
+}
+
+/*
+** The iterator passed as the first argument has the following fields set
+** as follows. This function sets up the rest of the iterator so that it
+** points to the first rowid in the doclist-index.
+**
+**   pData:
+**     pointer to doclist-index record, 
+**
+** When this function is called pIter->iLeafPgno is the page number the
+** doclist is associated with (the one featuring the term).
+*/
+static int fts5DlidxIterFirst(Fts5DlidxIter *pIter){
+  int i;
+  for(i=0; i<pIter->nLvl; i++){
+    fts5DlidxLvlNext(&pIter->aLvl[i]);
+  }
+  return pIter->aLvl[0].bEof;
+}
+
+
+static int fts5DlidxIterEof(Fts5Index *p, Fts5DlidxIter *pIter){
+  return p->rc!=SQLITE_OK || pIter->aLvl[0].bEof;
+}
+
+static void fts5DlidxIterLast(Fts5Index *p, Fts5DlidxIter *pIter){
+  int i;
+
+  /* Advance each level to the last entry on the last page */
+  for(i=pIter->nLvl-1; p->rc==SQLITE_OK && i>=0; i--){
+    Fts5DlidxLvl *pLvl = &pIter->aLvl[i];
+    while( fts5DlidxLvlNext(pLvl)==0 );
+    pLvl->bEof = 0;
+
+    if( i>0 ){
+      Fts5DlidxLvl *pChild = &pLvl[-1];
+      fts5DataRelease(pChild->pData);
+      memset(pChild, 0, sizeof(Fts5DlidxLvl));
+      pChild->pData = fts5DataRead(p, 
+          FTS5_DLIDX_ROWID(pIter->iSegid, i-1, pLvl->iLeafPgno)
+      );
+    }
+  }
+}
+
+/*
+** Move the iterator passed as the only argument to the previous entry.
+*/
+static int fts5DlidxLvlPrev(Fts5DlidxLvl *pLvl){
+  int iOff = pLvl->iOff;
+
+  assert( pLvl->bEof==0 );
+  if( iOff<=pLvl->iFirstOff ){
+    pLvl->bEof = 1;
+  }else{
+    u8 *a = pLvl->pData->p;
+    i64 iVal;
+    int iLimit;
+    int ii;
+    int nZero = 0;
+
+    /* Currently iOff points to the first byte of a varint. This block 
+    ** decrements iOff until it points to the first byte of the previous 
+    ** varint. Taking care not to read any memory locations that occur
+    ** before the buffer in memory.  */
+    iLimit = (iOff>9 ? iOff-9 : 0);
+    for(iOff--; iOff>iLimit; iOff--){
+      if( (a[iOff-1] & 0x80)==0 ) break;
+    }
+
+    fts5GetVarint(&a[iOff], (u64*)&iVal);
+    pLvl->iRowid -= iVal;
+    pLvl->iLeafPgno--;
+
+    /* Skip backwards past any 0x00 varints. */
+    for(ii=iOff-1; ii>=pLvl->iFirstOff && a[ii]==0x00; ii--){
+      nZero++;
+    }
+    if( ii>=pLvl->iFirstOff && (a[ii] & 0x80) ){
+      /* The byte immediately before the last 0x00 byte has the 0x80 bit
+      ** set. So the last 0x00 is only a varint 0 if there are 8 more 0x80
+      ** bytes before a[ii]. */
+      int bZero = 0;              /* True if last 0x00 counts */
+      if( (ii-8)>=pLvl->iFirstOff ){
+        int j;
+        for(j=1; j<=8 && (a[ii-j] & 0x80); j++);
+        bZero = (j>8);
+      }
+      if( bZero==0 ) nZero--;
+    }
+    pLvl->iLeafPgno -= nZero;
+    pLvl->iOff = iOff - nZero;
+  }
+
+  return pLvl->bEof;
+}
+
+static int fts5DlidxIterPrevR(Fts5Index *p, Fts5DlidxIter *pIter, int iLvl){
+  Fts5DlidxLvl *pLvl = &pIter->aLvl[iLvl];
+
+  assert( iLvl<pIter->nLvl );
+  if( fts5DlidxLvlPrev(pLvl) ){
+    if( (iLvl+1) < pIter->nLvl ){
+      fts5DlidxIterPrevR(p, pIter, iLvl+1);
+      if( pLvl[1].bEof==0 ){
+        fts5DataRelease(pLvl->pData);
+        memset(pLvl, 0, sizeof(Fts5DlidxLvl));
+        pLvl->pData = fts5DataRead(p, 
+            FTS5_DLIDX_ROWID(pIter->iSegid, iLvl, pLvl[1].iLeafPgno)
+        );
+        if( pLvl->pData ){
+          while( fts5DlidxLvlNext(pLvl)==0 );
+          pLvl->bEof = 0;
+        }
+      }
+    }
+  }
+
+  return pIter->aLvl[0].bEof;
+}
+static int fts5DlidxIterPrev(Fts5Index *p, Fts5DlidxIter *pIter){
+  return fts5DlidxIterPrevR(p, pIter, 0);
+}
+
+/*
+** Free a doclist-index iterator object allocated by fts5DlidxIterInit().
+*/
+static void fts5DlidxIterFree(Fts5DlidxIter *pIter){
+  if( pIter ){
+    int i;
+    for(i=0; i<pIter->nLvl; i++){
+      fts5DataRelease(pIter->aLvl[i].pData);
+    }
+    sqlite3_free(pIter);
+  }
+}
+
+static Fts5DlidxIter *fts5DlidxIterInit(
+  Fts5Index *p,                   /* Fts5 Backend to iterate within */
+  int bRev,                       /* True for ORDER BY ASC */
+  int iSegid,                     /* Segment id */
+  int iLeafPg                     /* Leaf page number to load dlidx for */
+){
+  Fts5DlidxIter *pIter = 0;
+  int i;
+  int bDone = 0;
+
+  for(i=0; p->rc==SQLITE_OK && bDone==0; i++){
+    int nByte = sizeof(Fts5DlidxIter) + i * sizeof(Fts5DlidxLvl);
+    Fts5DlidxIter *pNew;
+
+    pNew = (Fts5DlidxIter*)sqlite3_realloc(pIter, nByte);
+    if( pNew==0 ){
+      p->rc = SQLITE_NOMEM;
+    }else{
+      i64 iRowid = FTS5_DLIDX_ROWID(iSegid, i, iLeafPg);
+      Fts5DlidxLvl *pLvl = &pNew->aLvl[i];
+      pIter = pNew;
+      memset(pLvl, 0, sizeof(Fts5DlidxLvl));
+      pLvl->pData = fts5DataRead(p, iRowid);
+      if( pLvl->pData && (pLvl->pData->p[0] & 0x0001)==0 ){
+        bDone = 1;
+      }
+      pIter->nLvl = i+1;
+    }
+  }
+
+  if( p->rc==SQLITE_OK ){
+    pIter->iSegid = iSegid;
+    if( bRev==0 ){
+      fts5DlidxIterFirst(pIter);
+    }else{
+      fts5DlidxIterLast(p, pIter);
+    }
+  }
+
+  if( p->rc!=SQLITE_OK ){
+    fts5DlidxIterFree(pIter);
+    pIter = 0;
+  }
+
+  return pIter;
+}
+
+static i64 fts5DlidxIterRowid(Fts5DlidxIter *pIter){
+  return pIter->aLvl[0].iRowid;
+}
+static int fts5DlidxIterPgno(Fts5DlidxIter *pIter){
+  return pIter->aLvl[0].iLeafPgno;
+}
+
+/*
+** Load the next leaf page into the segment iterator.
+*/
+static void fts5SegIterNextPage(
+  Fts5Index *p,                   /* FTS5 backend object */
+  Fts5SegIter *pIter              /* Iterator to advance to next page */
+){
+  Fts5Data *pLeaf;
+  Fts5StructureSegment *pSeg = pIter->pSeg;
+  fts5DataRelease(pIter->pLeaf);
+  pIter->iLeafPgno++;
+  if( pIter->pNextLeaf ){
+    pIter->pLeaf = pIter->pNextLeaf;
+    pIter->pNextLeaf = 0;
+  }else if( pIter->iLeafPgno<=pSeg->pgnoLast ){
+    pIter->pLeaf = fts5LeafRead(p, 
+        FTS5_SEGMENT_ROWID(pSeg->iSegid, pIter->iLeafPgno)
+    );
+  }else{
+    pIter->pLeaf = 0;
+  }
+  pLeaf = pIter->pLeaf;
+
+  if( pLeaf ){
+    pIter->iPgidxOff = pLeaf->szLeaf;
+    if( fts5LeafIsTermless(pLeaf) ){
+      pIter->iEndofDoclist = pLeaf->nn+1;
+    }else{
+      pIter->iPgidxOff += fts5GetVarint32(&pLeaf->p[pIter->iPgidxOff],
+          pIter->iEndofDoclist
+      );
+    }
+  }
+}
+
+/*
+** Argument p points to a buffer containing a varint to be interpreted as a
+** position list size field. Read the varint and return the number of bytes
+** read. Before returning, set *pnSz to the number of bytes in the position
+** list, and *pbDel to true if the delete flag is set, or false otherwise.
+*/
+static int fts5GetPoslistSize(const u8 *p, int *pnSz, int *pbDel){
+  int nSz;
+  int n = 0;
+  fts5FastGetVarint32(p, n, nSz);
+  assert_nc( nSz>=0 );
+  *pnSz = nSz/2;
+  *pbDel = nSz & 0x0001;
+  return n;
+}
+
+/*
+** Fts5SegIter.iLeafOffset currently points to the first byte of a
+** position-list size field. Read the value of the field and store it
+** in the following variables:
+**
+**   Fts5SegIter.nPos
+**   Fts5SegIter.bDel
+**
+** Leave Fts5SegIter.iLeafOffset pointing to the first byte of the 
+** position list content (if any).
+*/
+static void fts5SegIterLoadNPos(Fts5Index *p, Fts5SegIter *pIter){
+  if( p->rc==SQLITE_OK ){
+    int iOff = pIter->iLeafOffset;  /* Offset to read at */
+    ASSERT_SZLEAF_OK(pIter->pLeaf);
+    if( p->pConfig->eDetail==FTS5_DETAIL_NONE ){
+      int iEod = MIN(pIter->iEndofDoclist, pIter->pLeaf->szLeaf);
+      pIter->bDel = 0;
+      pIter->nPos = 1;
+      if( iOff<iEod && pIter->pLeaf->p[iOff]==0 ){
+        pIter->bDel = 1;
+        iOff++;
+        if( iOff<iEod && pIter->pLeaf->p[iOff]==0 ){
+          pIter->nPos = 1;
+          iOff++;
+        }else{
+          pIter->nPos = 0;
+        }
+      }
+    }else{
+      int nSz;
+      fts5FastGetVarint32(pIter->pLeaf->p, iOff, nSz);
+      pIter->bDel = (nSz & 0x0001);
+      pIter->nPos = nSz>>1;
+      assert_nc( pIter->nPos>=0 );
+    }
+    pIter->iLeafOffset = iOff;
+  }
+}
+
+static void fts5SegIterLoadRowid(Fts5Index *p, Fts5SegIter *pIter){
+  u8 *a = pIter->pLeaf->p;        /* Buffer to read data from */
+  int iOff = pIter->iLeafOffset;
+
+  ASSERT_SZLEAF_OK(pIter->pLeaf);
+  if( iOff>=pIter->pLeaf->szLeaf ){
+    fts5SegIterNextPage(p, pIter);
+    if( pIter->pLeaf==0 ){
+      if( p->rc==SQLITE_OK ) p->rc = FTS5_CORRUPT;
+      return;
+    }
+    iOff = 4;
+    a = pIter->pLeaf->p;
+  }
+  iOff += sqlite3Fts5GetVarint(&a[iOff], (u64*)&pIter->iRowid);
+  pIter->iLeafOffset = iOff;
+}
+
+/*
+** Fts5SegIter.iLeafOffset currently points to the first byte of the 
+** "nSuffix" field of a term. Function parameter nKeep contains the value
+** of the "nPrefix" field (if there was one - it is passed 0 if this is
+** the first term in the segment).
+**
+** This function populates:
+**
+**   Fts5SegIter.term
+**   Fts5SegIter.rowid
+**
+** accordingly and leaves (Fts5SegIter.iLeafOffset) set to the content of
+** the first position list. The position list belonging to document 
+** (Fts5SegIter.iRowid).
+*/
+static void fts5SegIterLoadTerm(Fts5Index *p, Fts5SegIter *pIter, int nKeep){
+  u8 *a = pIter->pLeaf->p;        /* Buffer to read data from */
+  int iOff = pIter->iLeafOffset;  /* Offset to read at */
+  int nNew;                       /* Bytes of new data */
+
+  iOff += fts5GetVarint32(&a[iOff], nNew);
+  if( iOff+nNew>pIter->pLeaf->nn ){
+    p->rc = FTS5_CORRUPT;
+    return;
+  }
+  pIter->term.n = nKeep;
+  fts5BufferAppendBlob(&p->rc, &pIter->term, nNew, &a[iOff]);
+  iOff += nNew;
+  pIter->iTermLeafOffset = iOff;
+  pIter->iTermLeafPgno = pIter->iLeafPgno;
+  pIter->iLeafOffset = iOff;
+
+  if( pIter->iPgidxOff>=pIter->pLeaf->nn ){
+    pIter->iEndofDoclist = pIter->pLeaf->nn+1;
+  }else{
+    int nExtra;
+    pIter->iPgidxOff += fts5GetVarint32(&a[pIter->iPgidxOff], nExtra);
+    pIter->iEndofDoclist += nExtra;
+  }
+
+  fts5SegIterLoadRowid(p, pIter);
+}
+
+static void fts5SegIterNext(Fts5Index*, Fts5SegIter*, int*);
+static void fts5SegIterNext_Reverse(Fts5Index*, Fts5SegIter*, int*);
+static void fts5SegIterNext_None(Fts5Index*, Fts5SegIter*, int*);
+
+static void fts5SegIterSetNext(Fts5Index *p, Fts5SegIter *pIter){
+  if( pIter->flags & FTS5_SEGITER_REVERSE ){
+    pIter->xNext = fts5SegIterNext_Reverse;
+  }else if( p->pConfig->eDetail==FTS5_DETAIL_NONE ){
+    pIter->xNext = fts5SegIterNext_None;
+  }else{
+    pIter->xNext = fts5SegIterNext;
+  }
+}
+
+/*
+** Initialize the iterator object pIter to iterate through the entries in
+** segment pSeg. The iterator is left pointing to the first entry when 
+** this function returns.
+**
+** If an error occurs, Fts5Index.rc is set to an appropriate error code. If 
+** an error has already occurred when this function is called, it is a no-op.
+*/
+static void fts5SegIterInit(
+  Fts5Index *p,                   /* FTS index object */
+  Fts5StructureSegment *pSeg,     /* Description of segment */
+  Fts5SegIter *pIter              /* Object to populate */
+){
+  if( pSeg->pgnoFirst==0 ){
+    /* This happens if the segment is being used as an input to an incremental
+    ** merge and all data has already been "trimmed". See function
+    ** fts5TrimSegments() for details. In this case leave the iterator empty.
+    ** The caller will see the (pIter->pLeaf==0) and assume the iterator is
+    ** at EOF already. */
+    assert( pIter->pLeaf==0 );
+    return;
+  }
+
+  if( p->rc==SQLITE_OK ){
+    memset(pIter, 0, sizeof(*pIter));
+    fts5SegIterSetNext(p, pIter);
+    pIter->pSeg = pSeg;
+    pIter->iLeafPgno = pSeg->pgnoFirst-1;
+    fts5SegIterNextPage(p, pIter);
+  }
+
+  if( p->rc==SQLITE_OK ){
+    pIter->iLeafOffset = 4;
+    assert_nc( pIter->pLeaf->nn>4 );
+    assert( fts5LeafFirstTermOff(pIter->pLeaf)==4 );
+    pIter->iPgidxOff = pIter->pLeaf->szLeaf+1;
+    fts5SegIterLoadTerm(p, pIter, 0);
+    fts5SegIterLoadNPos(p, pIter);
+  }
+}
+
+/*
+** This function is only ever called on iterators created by calls to
+** Fts5IndexQuery() with the FTS5INDEX_QUERY_DESC flag set.
+**
+** The iterator is in an unusual state when this function is called: the
+** Fts5SegIter.iLeafOffset variable is set to the offset of the start of
+** the position-list size field for the first relevant rowid on the page.
+** Fts5SegIter.rowid is set, but nPos and bDel are not.
+**
+** This function advances the iterator so that it points to the last 
+** relevant rowid on the page and, if necessary, initializes the 
+** aRowidOffset[] and iRowidOffset variables. At this point the iterator
+** is in its regular state - Fts5SegIter.iLeafOffset points to the first
+** byte of the position list content associated with said rowid.
+*/
+static void fts5SegIterReverseInitPage(Fts5Index *p, Fts5SegIter *pIter){
+  int eDetail = p->pConfig->eDetail;
+  int n = pIter->pLeaf->szLeaf;
+  int i = pIter->iLeafOffset;
+  u8 *a = pIter->pLeaf->p;
+  int iRowidOffset = 0;
+
+  if( n>pIter->iEndofDoclist ){
+    n = pIter->iEndofDoclist;
+  }
+
+  ASSERT_SZLEAF_OK(pIter->pLeaf);
+  while( 1 ){
+    i64 iDelta = 0;
+
+    if( eDetail==FTS5_DETAIL_NONE ){
+      /* todo */
+      if( i<n && a[i]==0 ){
+        i++;
+        if( i<n && a[i]==0 ) i++;
+      }
+    }else{
+      int nPos;
+      int bDummy;
+      i += fts5GetPoslistSize(&a[i], &nPos, &bDummy);
+      i += nPos;
+    }
+    if( i>=n ) break;
+    i += fts5GetVarint(&a[i], (u64*)&iDelta);
+    pIter->iRowid += iDelta;
+
+    /* If necessary, grow the pIter->aRowidOffset[] array. */
+    if( iRowidOffset>=pIter->nRowidOffset ){
+      int nNew = pIter->nRowidOffset + 8;
+      int *aNew = (int*)sqlite3_realloc(pIter->aRowidOffset, nNew*sizeof(int));
+      if( aNew==0 ){
+        p->rc = SQLITE_NOMEM;
+        break;
+      }
+      pIter->aRowidOffset = aNew;
+      pIter->nRowidOffset = nNew;
+    }
+
+    pIter->aRowidOffset[iRowidOffset++] = pIter->iLeafOffset;
+    pIter->iLeafOffset = i;
+  }
+  pIter->iRowidOffset = iRowidOffset;
+  fts5SegIterLoadNPos(p, pIter);
+}
+
+/*
+**
+*/
+static void fts5SegIterReverseNewPage(Fts5Index *p, Fts5SegIter *pIter){
+  assert( pIter->flags & FTS5_SEGITER_REVERSE );
+  assert( pIter->flags & FTS5_SEGITER_ONETERM );
+
+  fts5DataRelease(pIter->pLeaf);
+  pIter->pLeaf = 0;
+  while( p->rc==SQLITE_OK && pIter->iLeafPgno>pIter->iTermLeafPgno ){
+    Fts5Data *pNew;
+    pIter->iLeafPgno--;
+    pNew = fts5DataRead(p, FTS5_SEGMENT_ROWID(
+          pIter->pSeg->iSegid, pIter->iLeafPgno
+    ));
+    if( pNew ){
+      /* iTermLeafOffset may be equal to szLeaf if the term is the last
+      ** thing on the page - i.e. the first rowid is on the following page.
+      ** In this case leave pIter->pLeaf==0, this iterator is at EOF. */
+      if( pIter->iLeafPgno==pIter->iTermLeafPgno ){
+        assert( pIter->pLeaf==0 );
+        if( pIter->iTermLeafOffset<pNew->szLeaf ){
+          pIter->pLeaf = pNew;
+          pIter->iLeafOffset = pIter->iTermLeafOffset;
+        }
+      }else{
+        int iRowidOff;
+        iRowidOff = fts5LeafFirstRowidOff(pNew);
+        if( iRowidOff ){
+          pIter->pLeaf = pNew;
+          pIter->iLeafOffset = iRowidOff;
+        }
+      }
+
+      if( pIter->pLeaf ){
+        u8 *a = &pIter->pLeaf->p[pIter->iLeafOffset];
+        pIter->iLeafOffset += fts5GetVarint(a, (u64*)&pIter->iRowid);
+        break;
+      }else{
+        fts5DataRelease(pNew);
+      }
+    }
+  }
+
+  if( pIter->pLeaf ){
+    pIter->iEndofDoclist = pIter->pLeaf->nn+1;
+    fts5SegIterReverseInitPage(p, pIter);
+  }
+}
+
+/*
+** Return true if the iterator passed as the second argument currently
+** points to a delete marker. A delete marker is an entry with a 0 byte
+** position-list.
+*/
+static int fts5MultiIterIsEmpty(Fts5Index *p, Fts5Iter *pIter){
+  Fts5SegIter *pSeg = &pIter->aSeg[pIter->aFirst[1].iFirst];
+  return (p->rc==SQLITE_OK && pSeg->pLeaf && pSeg->nPos==0);
+}
+
+/*
+** Advance iterator pIter to the next entry.
+**
+** This version of fts5SegIterNext() is only used by reverse iterators.
+*/
+static void fts5SegIterNext_Reverse(
+  Fts5Index *p,                   /* FTS5 backend object */
+  Fts5SegIter *pIter,             /* Iterator to advance */
+  int *pbUnused                   /* Unused */
+){
+  assert( pIter->flags & FTS5_SEGITER_REVERSE );
+  assert( pIter->pNextLeaf==0 );
+  UNUSED_PARAM(pbUnused);
+
+  if( pIter->iRowidOffset>0 ){
+    u8 *a = pIter->pLeaf->p;
+    int iOff;
+    i64 iDelta;
+
+    pIter->iRowidOffset--;
+    pIter->iLeafOffset = pIter->aRowidOffset[pIter->iRowidOffset];
+    fts5SegIterLoadNPos(p, pIter);
+    iOff = pIter->iLeafOffset;
+    if( p->pConfig->eDetail!=FTS5_DETAIL_NONE ){
+      iOff += pIter->nPos;
+    }
+    fts5GetVarint(&a[iOff], (u64*)&iDelta);
+    pIter->iRowid -= iDelta;
+  }else{
+    fts5SegIterReverseNewPage(p, pIter);
+  }
+}
+
+/*
+** Advance iterator pIter to the next entry.
+**
+** This version of fts5SegIterNext() is only used if detail=none and the
+** iterator is not a reverse direction iterator.
+*/
+static void fts5SegIterNext_None(
+  Fts5Index *p,                   /* FTS5 backend object */
+  Fts5SegIter *pIter,             /* Iterator to advance */
+  int *pbNewTerm                  /* OUT: Set for new term */
+){
+  int iOff;
+
+  assert( p->rc==SQLITE_OK );
+  assert( (pIter->flags & FTS5_SEGITER_REVERSE)==0 );
+  assert( p->pConfig->eDetail==FTS5_DETAIL_NONE );
+
+  ASSERT_SZLEAF_OK(pIter->pLeaf);
+  iOff = pIter->iLeafOffset;
+
+  /* Next entry is on the next page */
+  if( pIter->pSeg && iOff>=pIter->pLeaf->szLeaf ){
+    fts5SegIterNextPage(p, pIter);
+    if( p->rc || pIter->pLeaf==0 ) return;
+    pIter->iRowid = 0;
+    iOff = 4;
+  }
+
+  if( iOff<pIter->iEndofDoclist ){
+    /* Next entry is on the current page */
+    i64 iDelta;
+    iOff += sqlite3Fts5GetVarint(&pIter->pLeaf->p[iOff], (u64*)&iDelta);
+    pIter->iLeafOffset = iOff;
+    pIter->iRowid += iDelta;
+  }else if( (pIter->flags & FTS5_SEGITER_ONETERM)==0 ){
+    if( pIter->pSeg ){
+      int nKeep = 0;
+      if( iOff!=fts5LeafFirstTermOff(pIter->pLeaf) ){
+        iOff += fts5GetVarint32(&pIter->pLeaf->p[iOff], nKeep);
+      }
+      pIter->iLeafOffset = iOff;
+      fts5SegIterLoadTerm(p, pIter, nKeep);
+    }else{
+      const u8 *pList = 0;
+      const char *zTerm = 0;
+      int nList;
+      sqlite3Fts5HashScanNext(p->pHash);
+      sqlite3Fts5HashScanEntry(p->pHash, &zTerm, &pList, &nList);
+      if( pList==0 ) goto next_none_eof;
+      pIter->pLeaf->p = (u8*)pList;
+      pIter->pLeaf->nn = nList;
+      pIter->pLeaf->szLeaf = nList;
+      pIter->iEndofDoclist = nList;
+      sqlite3Fts5BufferSet(&p->rc,&pIter->term, (int)strlen(zTerm), (u8*)zTerm);
+      pIter->iLeafOffset = fts5GetVarint(pList, (u64*)&pIter->iRowid);
+    }
+
+    if( pbNewTerm ) *pbNewTerm = 1;
+  }else{
+    goto next_none_eof;
+  }
+
+  fts5SegIterLoadNPos(p, pIter);
+
+  return;
+ next_none_eof:
+  fts5DataRelease(pIter->pLeaf);
+  pIter->pLeaf = 0;
+}
+
+
+/*
+** Advance iterator pIter to the next entry. 
+**
+** If an error occurs, Fts5Index.rc is set to an appropriate error code. It 
+** is not considered an error if the iterator reaches EOF. If an error has 
+** already occurred when this function is called, it is a no-op.
+*/
+static void fts5SegIterNext(
+  Fts5Index *p,                   /* FTS5 backend object */
+  Fts5SegIter *pIter,             /* Iterator to advance */
+  int *pbNewTerm                  /* OUT: Set for new term */
+){
+  Fts5Data *pLeaf = pIter->pLeaf;
+  int iOff;
+  int bNewTerm = 0;
+  int nKeep = 0;
+  u8 *a;
+  int n;
+
+  assert( pbNewTerm==0 || *pbNewTerm==0 );
+  assert( p->pConfig->eDetail!=FTS5_DETAIL_NONE );
+
+  /* Search for the end of the position list within the current page. */
+  a = pLeaf->p;
+  n = pLeaf->szLeaf;
+
+  ASSERT_SZLEAF_OK(pLeaf);
+  iOff = pIter->iLeafOffset + pIter->nPos;
+
+  if( iOff<n ){
+    /* The next entry is on the current page. */
+    assert_nc( iOff<=pIter->iEndofDoclist );
+    if( iOff>=pIter->iEndofDoclist ){
+      bNewTerm = 1;
+      if( iOff!=fts5LeafFirstTermOff(pLeaf) ){
+        iOff += fts5GetVarint32(&a[iOff], nKeep);
+      }
+    }else{
+      u64 iDelta;
+      iOff += sqlite3Fts5GetVarint(&a[iOff], &iDelta);
+      pIter->iRowid += iDelta;
+      assert_nc( iDelta>0 );
+    }
+    pIter->iLeafOffset = iOff;
+
+  }else if( pIter->pSeg==0 ){
+    const u8 *pList = 0;
+    const char *zTerm = 0;
+    int nList = 0;
+    assert( (pIter->flags & FTS5_SEGITER_ONETERM) || pbNewTerm );
+    if( 0==(pIter->flags & FTS5_SEGITER_ONETERM) ){
+      sqlite3Fts5HashScanNext(p->pHash);
+      sqlite3Fts5HashScanEntry(p->pHash, &zTerm, &pList, &nList);
+    }
+    if( pList==0 ){
+      fts5DataRelease(pIter->pLeaf);
+      pIter->pLeaf = 0;
+    }else{
+      pIter->pLeaf->p = (u8*)pList;
+      pIter->pLeaf->nn = nList;
+      pIter->pLeaf->szLeaf = nList;
+      pIter->iEndofDoclist = nList+1;
+      sqlite3Fts5BufferSet(&p->rc, &pIter->term, (int)strlen(zTerm),
+          (u8*)zTerm);
+      pIter->iLeafOffset = fts5GetVarint(pList, (u64*)&pIter->iRowid);
+      *pbNewTerm = 1;
+    }
+  }else{
+    iOff = 0;
+    /* Next entry is not on the current page */
+    while( iOff==0 ){
+      fts5SegIterNextPage(p, pIter);
+      pLeaf = pIter->pLeaf;
+      if( pLeaf==0 ) break;
+      ASSERT_SZLEAF_OK(pLeaf);
+      if( (iOff = fts5LeafFirstRowidOff(pLeaf)) && iOff<pLeaf->szLeaf ){
+        iOff += sqlite3Fts5GetVarint(&pLeaf->p[iOff], (u64*)&pIter->iRowid);
+        pIter->iLeafOffset = iOff;
+
+        if( pLeaf->nn>pLeaf->szLeaf ){
+          pIter->iPgidxOff = pLeaf->szLeaf + fts5GetVarint32(
+              &pLeaf->p[pLeaf->szLeaf], pIter->iEndofDoclist
+          );
+        }
+      }
+      else if( pLeaf->nn>pLeaf->szLeaf ){
+        pIter->iPgidxOff = pLeaf->szLeaf + fts5GetVarint32(
+            &pLeaf->p[pLeaf->szLeaf], iOff
+            );
+        pIter->iLeafOffset = iOff;
+        pIter->iEndofDoclist = iOff;
+        bNewTerm = 1;
+      }
+      assert_nc( iOff<pLeaf->szLeaf );
+      if( iOff>pLeaf->szLeaf ){
+        p->rc = FTS5_CORRUPT;
+        return;
+      }
+    }
+  }
+
+  /* Check if the iterator is now at EOF. If so, return early. */
+  if( pIter->pLeaf ){
+    if( bNewTerm ){
+      if( pIter->flags & FTS5_SEGITER_ONETERM ){
+        fts5DataRelease(pIter->pLeaf);
+        pIter->pLeaf = 0;
+      }else{
+        fts5SegIterLoadTerm(p, pIter, nKeep);
+        fts5SegIterLoadNPos(p, pIter);
+        if( pbNewTerm ) *pbNewTerm = 1;
+      }
+    }else{
+      /* The following could be done by calling fts5SegIterLoadNPos(). But
+      ** this block is particularly performance critical, so equivalent
+      ** code is inlined. 
+      **
+      ** Later: Switched back to fts5SegIterLoadNPos() because it supports
+      ** detail=none mode. Not ideal.
+      */
+      int nSz;
+      assert( p->rc==SQLITE_OK );
+      fts5FastGetVarint32(pIter->pLeaf->p, pIter->iLeafOffset, nSz);
+      pIter->bDel = (nSz & 0x0001);
+      pIter->nPos = nSz>>1;
+      assert_nc( pIter->nPos>=0 );
+    }
+  }
+}
+
+#define SWAPVAL(T, a, b) { T tmp; tmp=a; a=b; b=tmp; }
+
+#define fts5IndexSkipVarint(a, iOff) {            \
+  int iEnd = iOff+9;                              \
+  while( (a[iOff++] & 0x80) && iOff<iEnd );       \
+}
+
+/*
+** Iterator pIter currently points to the first rowid in a doclist. This
+** function sets the iterator up so that iterates in reverse order through
+** the doclist.
+*/
+static void fts5SegIterReverse(Fts5Index *p, Fts5SegIter *pIter){
+  Fts5DlidxIter *pDlidx = pIter->pDlidx;
+  Fts5Data *pLast = 0;
+  int pgnoLast = 0;
+
+  if( pDlidx ){
+    int iSegid = pIter->pSeg->iSegid;
+    pgnoLast = fts5DlidxIterPgno(pDlidx);
+    pLast = fts5DataRead(p, FTS5_SEGMENT_ROWID(iSegid, pgnoLast));
+  }else{
+    Fts5Data *pLeaf = pIter->pLeaf;         /* Current leaf data */
+
+    /* Currently, Fts5SegIter.iLeafOffset points to the first byte of
+    ** position-list content for the current rowid. Back it up so that it
+    ** points to the start of the position-list size field. */
+    int iPoslist;
+    if( pIter->iTermLeafPgno==pIter->iLeafPgno ){
+      iPoslist = pIter->iTermLeafOffset;
+    }else{
+      iPoslist = 4;
+    }
+    fts5IndexSkipVarint(pLeaf->p, iPoslist);
+    pIter->iLeafOffset = iPoslist;
+
+    /* If this condition is true then the largest rowid for the current
+    ** term may not be stored on the current page. So search forward to
+    ** see where said rowid really is.  */
+    if( pIter->iEndofDoclist>=pLeaf->szLeaf ){
+      int pgno;
+      Fts5StructureSegment *pSeg = pIter->pSeg;
+
+      /* The last rowid in the doclist may not be on the current page. Search
+      ** forward to find the page containing the last rowid.  */
+      for(pgno=pIter->iLeafPgno+1; !p->rc && pgno<=pSeg->pgnoLast; pgno++){
+        i64 iAbs = FTS5_SEGMENT_ROWID(pSeg->iSegid, pgno);
+        Fts5Data *pNew = fts5DataRead(p, iAbs);
+        if( pNew ){
+          int iRowid, bTermless;
+          iRowid = fts5LeafFirstRowidOff(pNew);
+          bTermless = fts5LeafIsTermless(pNew);
+          if( iRowid ){
+            SWAPVAL(Fts5Data*, pNew, pLast);
+            pgnoLast = pgno;
+          }
+          fts5DataRelease(pNew);
+          if( bTermless==0 ) break;
+        }
+      }
+    }
+  }
+
+  /* If pLast is NULL at this point, then the last rowid for this doclist
+  ** lies on the page currently indicated by the iterator. In this case 
+  ** pIter->iLeafOffset is already set to point to the position-list size
+  ** field associated with the first relevant rowid on the page.
+  **
+  ** Or, if pLast is non-NULL, then it is the page that contains the last
+  ** rowid. In this case configure the iterator so that it points to the
+  ** first rowid on this page.
+  */
+  if( pLast ){
+    int iOff;
+    fts5DataRelease(pIter->pLeaf);
+    pIter->pLeaf = pLast;
+    pIter->iLeafPgno = pgnoLast;
+    iOff = fts5LeafFirstRowidOff(pLast);
+    iOff += fts5GetVarint(&pLast->p[iOff], (u64*)&pIter->iRowid);
+    pIter->iLeafOffset = iOff;
+
+    if( fts5LeafIsTermless(pLast) ){
+      pIter->iEndofDoclist = pLast->nn+1;
+    }else{
+      pIter->iEndofDoclist = fts5LeafFirstTermOff(pLast);
+    }
+
+  }
+
+  fts5SegIterReverseInitPage(p, pIter);
+}
+
+/*
+** Iterator pIter currently points to the first rowid of a doclist.
+** There is a doclist-index associated with the final term on the current 
+** page. If the current term is the last term on the page, load the 
+** doclist-index from disk and initialize an iterator at (pIter->pDlidx).
+*/
+static void fts5SegIterLoadDlidx(Fts5Index *p, Fts5SegIter *pIter){
+  int iSeg = pIter->pSeg->iSegid;
+  int bRev = (pIter->flags & FTS5_SEGITER_REVERSE);
+  Fts5Data *pLeaf = pIter->pLeaf; /* Current leaf data */
+
+  assert( pIter->flags & FTS5_SEGITER_ONETERM );
+  assert( pIter->pDlidx==0 );
+
+  /* Check if the current doclist ends on this page. If it does, return
+  ** early without loading the doclist-index (as it belongs to a different
+  ** term. */
+  if( pIter->iTermLeafPgno==pIter->iLeafPgno 
+   && pIter->iEndofDoclist<pLeaf->szLeaf 
+  ){
+    return;
+  }
+
+  pIter->pDlidx = fts5DlidxIterInit(p, bRev, iSeg, pIter->iTermLeafPgno);
+}
+
+/*
+** The iterator object passed as the second argument currently contains
+** no valid values except for the Fts5SegIter.pLeaf member variable. This
+** function searches the leaf page for a term matching (pTerm/nTerm).
+**
+** If the specified term is found on the page, then the iterator is left
+** pointing to it. If argument bGe is zero and the term is not found,
+** the iterator is left pointing at EOF.
+**
+** If bGe is non-zero and the specified term is not found, then the
+** iterator is left pointing to the smallest term in the segment that
+** is larger than the specified term, even if this term is not on the
+** current page.
+*/
+static void fts5LeafSeek(
+  Fts5Index *p,                   /* Leave any error code here */
+  int bGe,                        /* True for a >= search */
+  Fts5SegIter *pIter,             /* Iterator to seek */
+  const u8 *pTerm, int nTerm      /* Term to search for */
+){
+  int iOff;
+  const u8 *a = pIter->pLeaf->p;
+  int szLeaf = pIter->pLeaf->szLeaf;
+  int n = pIter->pLeaf->nn;
+
+  int nMatch = 0;
+  int nKeep = 0;
+  int nNew = 0;
+  int iTermOff;
+  int iPgidx;                     /* Current offset in pgidx */
+  int bEndOfPage = 0;
+
+  assert( p->rc==SQLITE_OK );
+
+  iPgidx = szLeaf;
+  iPgidx += fts5GetVarint32(&a[iPgidx], iTermOff);
+  iOff = iTermOff;
+  if( iOff>n ){
+    p->rc = FTS5_CORRUPT;
+    return;
+  }
+
+  while( 1 ){
+
+    /* Figure out how many new bytes are in this term */
+    fts5FastGetVarint32(a, iOff, nNew);
+    if( nKeep<nMatch ){
+      goto search_failed;
+    }
+
+    assert( nKeep>=nMatch );
+    if( nKeep==nMatch ){
+      int nCmp;
+      int i;
+      nCmp = MIN(nNew, nTerm-nMatch);
+      for(i=0; i<nCmp; i++){
+        if( a[iOff+i]!=pTerm[nMatch+i] ) break;
+      }
+      nMatch += i;
+
+      if( nTerm==nMatch ){
+        if( i==nNew ){
+          goto search_success;
+        }else{
+          goto search_failed;
+        }
+      }else if( i<nNew && a[iOff+i]>pTerm[nMatch] ){
+        goto search_failed;
+      }
+    }
+
+    if( iPgidx>=n ){
+      bEndOfPage = 1;
+      break;
+    }
+
+    iPgidx += fts5GetVarint32(&a[iPgidx], nKeep);
+    iTermOff += nKeep;
+    iOff = iTermOff;
+
+    if( iOff>=n ){
+      p->rc = FTS5_CORRUPT;
+      return;
+    }
+
+    /* Read the nKeep field of the next term. */
+    fts5FastGetVarint32(a, iOff, nKeep);
+  }
+
+ search_failed:
+  if( bGe==0 ){
+    fts5DataRelease(pIter->pLeaf);
+    pIter->pLeaf = 0;
+    return;
+  }else if( bEndOfPage ){
+    do {
+      fts5SegIterNextPage(p, pIter);
+      if( pIter->pLeaf==0 ) return;
+      a = pIter->pLeaf->p;
+      if( fts5LeafIsTermless(pIter->pLeaf)==0 ){
+        iPgidx = pIter->pLeaf->szLeaf;
+        iPgidx += fts5GetVarint32(&pIter->pLeaf->p[iPgidx], iOff);
+        if( iOff<4 || iOff>=pIter->pLeaf->szLeaf ){
+          p->rc = FTS5_CORRUPT;
+        }else{
+          nKeep = 0;
+          iTermOff = iOff;
+          n = pIter->pLeaf->nn;
+          iOff += fts5GetVarint32(&a[iOff], nNew);
+          break;
+        }
+      }
+    }while( 1 );
+  }
+
+ search_success:
+
+  pIter->iLeafOffset = iOff + nNew;
+  pIter->iTermLeafOffset = pIter->iLeafOffset;
+  pIter->iTermLeafPgno = pIter->iLeafPgno;
+
+  fts5BufferSet(&p->rc, &pIter->term, nKeep, pTerm);
+  fts5BufferAppendBlob(&p->rc, &pIter->term, nNew, &a[iOff]);
+
+  if( iPgidx>=n ){
+    pIter->iEndofDoclist = pIter->pLeaf->nn+1;
+  }else{
+    int nExtra;
+    iPgidx += fts5GetVarint32(&a[iPgidx], nExtra);
+    pIter->iEndofDoclist = iTermOff + nExtra;
+  }
+  pIter->iPgidxOff = iPgidx;
+
+  fts5SegIterLoadRowid(p, pIter);
+  fts5SegIterLoadNPos(p, pIter);
+}
+
+static sqlite3_stmt *fts5IdxSelectStmt(Fts5Index *p){
+  if( p->pIdxSelect==0 ){
+    Fts5Config *pConfig = p->pConfig;
+    fts5IndexPrepareStmt(p, &p->pIdxSelect, sqlite3_mprintf(
+          "SELECT pgno FROM '%q'.'%q_idx' WHERE "
+          "segid=? AND term<=? ORDER BY term DESC LIMIT 1",
+          pConfig->zDb, pConfig->zName
+    ));
+  }
+  return p->pIdxSelect;
+}
+
+/*
+** Initialize the object pIter to point to term pTerm/nTerm within segment
+** pSeg. If there is no such term in the index, the iterator is set to EOF.
+**
+** If an error occurs, Fts5Index.rc is set to an appropriate error code. If 
+** an error has already occurred when this function is called, it is a no-op.
+*/
+static void fts5SegIterSeekInit(
+  Fts5Index *p,                   /* FTS5 backend */
+  const u8 *pTerm, int nTerm,     /* Term to seek to */
+  int flags,                      /* Mask of FTS5INDEX_XXX flags */
+  Fts5StructureSegment *pSeg,     /* Description of segment */
+  Fts5SegIter *pIter              /* Object to populate */
+){
+  int iPg = 1;
+  int bGe = (flags & FTS5INDEX_QUERY_SCAN);
+  int bDlidx = 0;                 /* True if there is a doclist-index */
+  sqlite3_stmt *pIdxSelect = 0;
+
+  assert( bGe==0 || (flags & FTS5INDEX_QUERY_DESC)==0 );
+  assert( pTerm && nTerm );
+  memset(pIter, 0, sizeof(*pIter));
+  pIter->pSeg = pSeg;
+
+  /* This block sets stack variable iPg to the leaf page number that may
+  ** contain term (pTerm/nTerm), if it is present in the segment. */
+  pIdxSelect = fts5IdxSelectStmt(p);
+  if( p->rc ) return;
+  sqlite3_bind_int(pIdxSelect, 1, pSeg->iSegid);
+  sqlite3_bind_blob(pIdxSelect, 2, pTerm, nTerm, SQLITE_STATIC);
+  if( SQLITE_ROW==sqlite3_step(pIdxSelect) ){
+    i64 val = sqlite3_column_int(pIdxSelect, 0);
+    iPg = (int)(val>>1);
+    bDlidx = (val & 0x0001);
+  }
+  p->rc = sqlite3_reset(pIdxSelect);
+
+  if( iPg<pSeg->pgnoFirst ){
+    iPg = pSeg->pgnoFirst;
+    bDlidx = 0;
+  }
+
+  pIter->iLeafPgno = iPg - 1;
+  fts5SegIterNextPage(p, pIter);
+
+  if( pIter->pLeaf ){
+    fts5LeafSeek(p, bGe, pIter, pTerm, nTerm);
+  }
+
+  if( p->rc==SQLITE_OK && bGe==0 ){
+    pIter->flags |= FTS5_SEGITER_ONETERM;
+    if( pIter->pLeaf ){
+      if( flags & FTS5INDEX_QUERY_DESC ){
+        pIter->flags |= FTS5_SEGITER_REVERSE;
+      }
+      if( bDlidx ){
+        fts5SegIterLoadDlidx(p, pIter);
+      }
+      if( flags & FTS5INDEX_QUERY_DESC ){
+        fts5SegIterReverse(p, pIter);
+      }
+    }
+  }
+
+  fts5SegIterSetNext(p, pIter);
+
+  /* Either:
+  **
+  **   1) an error has occurred, or
+  **   2) the iterator points to EOF, or
+  **   3) the iterator points to an entry with term (pTerm/nTerm), or
+  **   4) the FTS5INDEX_QUERY_SCAN flag was set and the iterator points
+  **      to an entry with a term greater than or equal to (pTerm/nTerm).
+  */
+  assert( p->rc!=SQLITE_OK                                          /* 1 */
+   || pIter->pLeaf==0                                               /* 2 */
+   || fts5BufferCompareBlob(&pIter->term, pTerm, nTerm)==0          /* 3 */
+   || (bGe && fts5BufferCompareBlob(&pIter->term, pTerm, nTerm)>0)  /* 4 */
+  );
+}
+
+/*
+** Initialize the object pIter to point to term pTerm/nTerm within the
+** in-memory hash table. If there is no such term in the hash-table, the 
+** iterator is set to EOF.
+**
+** If an error occurs, Fts5Index.rc is set to an appropriate error code. If 
+** an error has already occurred when this function is called, it is a no-op.
+*/
+static void fts5SegIterHashInit(
+  Fts5Index *p,                   /* FTS5 backend */
+  const u8 *pTerm, int nTerm,     /* Term to seek to */
+  int flags,                      /* Mask of FTS5INDEX_XXX flags */
+  Fts5SegIter *pIter              /* Object to populate */
+){
+  const u8 *pList = 0;
+  int nList = 0;
+  const u8 *z = 0;
+  int n = 0;
+
+  assert( p->pHash );
+  assert( p->rc==SQLITE_OK );
+
+  if( pTerm==0 || (flags & FTS5INDEX_QUERY_SCAN) ){
+    p->rc = sqlite3Fts5HashScanInit(p->pHash, (const char*)pTerm, nTerm);
+    sqlite3Fts5HashScanEntry(p->pHash, (const char**)&z, &pList, &nList);
+    n = (z ? (int)strlen((const char*)z) : 0);
+  }else{
+    pIter->flags |= FTS5_SEGITER_ONETERM;
+    sqlite3Fts5HashQuery(p->pHash, (const char*)pTerm, nTerm, &pList, &nList);
+    z = pTerm;
+    n = nTerm;
+  }
+
+  if( pList ){
+    Fts5Data *pLeaf;
+    sqlite3Fts5BufferSet(&p->rc, &pIter->term, n, z);
+    pLeaf = fts5IdxMalloc(p, sizeof(Fts5Data));
+    if( pLeaf==0 ) return;
+    pLeaf->p = (u8*)pList;
+    pLeaf->nn = pLeaf->szLeaf = nList;
+    pIter->pLeaf = pLeaf;
+    pIter->iLeafOffset = fts5GetVarint(pLeaf->p, (u64*)&pIter->iRowid);
+    pIter->iEndofDoclist = pLeaf->nn;
+
+    if( flags & FTS5INDEX_QUERY_DESC ){
+      pIter->flags |= FTS5_SEGITER_REVERSE;
+      fts5SegIterReverseInitPage(p, pIter);
+    }else{
+      fts5SegIterLoadNPos(p, pIter);
+    }
+  }
+
+  fts5SegIterSetNext(p, pIter);
+}
+
+/*
+** Zero the iterator passed as the only argument.
+*/
+static void fts5SegIterClear(Fts5SegIter *pIter){
+  fts5BufferFree(&pIter->term);
+  fts5DataRelease(pIter->pLeaf);
+  fts5DataRelease(pIter->pNextLeaf);
+  fts5DlidxIterFree(pIter->pDlidx);
+  sqlite3_free(pIter->aRowidOffset);
+  memset(pIter, 0, sizeof(Fts5SegIter));
+}
+
+#ifdef SQLITE_DEBUG
+
+/*
+** This function is used as part of the big assert() procedure implemented by
+** fts5AssertMultiIterSetup(). It ensures that the result currently stored
+** in *pRes is the correct result of comparing the current positions of the
+** two iterators.
+*/
+static void fts5AssertComparisonResult(
+  Fts5Iter *pIter, 
+  Fts5SegIter *p1,
+  Fts5SegIter *p2,
+  Fts5CResult *pRes
+){
+  int i1 = p1 - pIter->aSeg;
+  int i2 = p2 - pIter->aSeg;
+
+  if( p1->pLeaf || p2->pLeaf ){
+    if( p1->pLeaf==0 ){
+      assert( pRes->iFirst==i2 );
+    }else if( p2->pLeaf==0 ){
+      assert( pRes->iFirst==i1 );
+    }else{
+      int nMin = MIN(p1->term.n, p2->term.n);
+      int res = memcmp(p1->term.p, p2->term.p, nMin);
+      if( res==0 ) res = p1->term.n - p2->term.n;
+
+      if( res==0 ){
+        assert( pRes->bTermEq==1 );
+        assert( p1->iRowid!=p2->iRowid );
+        res = ((p1->iRowid > p2->iRowid)==pIter->bRev) ? -1 : 1;
+      }else{
+        assert( pRes->bTermEq==0 );
+      }
+
+      if( res<0 ){
+        assert( pRes->iFirst==i1 );
+      }else{
+        assert( pRes->iFirst==i2 );
+      }
+    }
+  }
+}
+
+/*
+** This function is a no-op unless SQLITE_DEBUG is defined when this module
+** is compiled. In that case, this function is essentially an assert() 
+** statement used to verify that the contents of the pIter->aFirst[] array
+** are correct.
+*/
+static void fts5AssertMultiIterSetup(Fts5Index *p, Fts5Iter *pIter){
+  if( p->rc==SQLITE_OK ){
+    Fts5SegIter *pFirst = &pIter->aSeg[ pIter->aFirst[1].iFirst ];
+    int i;
+
+    assert( (pFirst->pLeaf==0)==pIter->base.bEof );
+
+    /* Check that pIter->iSwitchRowid is set correctly. */
+    for(i=0; i<pIter->nSeg; i++){
+      Fts5SegIter *p1 = &pIter->aSeg[i];
+      assert( p1==pFirst 
+           || p1->pLeaf==0 
+           || fts5BufferCompare(&pFirst->term, &p1->term) 
+           || p1->iRowid==pIter->iSwitchRowid
+           || (p1->iRowid<pIter->iSwitchRowid)==pIter->bRev
+      );
+    }
+
+    for(i=0; i<pIter->nSeg; i+=2){
+      Fts5SegIter *p1 = &pIter->aSeg[i];
+      Fts5SegIter *p2 = &pIter->aSeg[i+1];
+      Fts5CResult *pRes = &pIter->aFirst[(pIter->nSeg + i) / 2];
+      fts5AssertComparisonResult(pIter, p1, p2, pRes);
+    }
+
+    for(i=1; i<(pIter->nSeg / 2); i+=2){
+      Fts5SegIter *p1 = &pIter->aSeg[ pIter->aFirst[i*2].iFirst ];
+      Fts5SegIter *p2 = &pIter->aSeg[ pIter->aFirst[i*2+1].iFirst ];
+      Fts5CResult *pRes = &pIter->aFirst[i];
+      fts5AssertComparisonResult(pIter, p1, p2, pRes);
+    }
+  }
+}
+#else
+# define fts5AssertMultiIterSetup(x,y)
+#endif
+
+/*
+** Do the comparison necessary to populate pIter->aFirst[iOut].
+**
+** If the returned value is non-zero, then it is the index of an entry
+** in the pIter->aSeg[] array that is (a) not at EOF, and (b) pointing
+** to a key that is a duplicate of another, higher priority, 
+** segment-iterator in the pSeg->aSeg[] array.
+*/
+static int fts5MultiIterDoCompare(Fts5Iter *pIter, int iOut){
+  int i1;                         /* Index of left-hand Fts5SegIter */
+  int i2;                         /* Index of right-hand Fts5SegIter */
+  int iRes;
+  Fts5SegIter *p1;                /* Left-hand Fts5SegIter */
+  Fts5SegIter *p2;                /* Right-hand Fts5SegIter */
+  Fts5CResult *pRes = &pIter->aFirst[iOut];
+
+  assert( iOut<pIter->nSeg && iOut>0 );
+  assert( pIter->bRev==0 || pIter->bRev==1 );
+
+  if( iOut>=(pIter->nSeg/2) ){
+    i1 = (iOut - pIter->nSeg/2) * 2;
+    i2 = i1 + 1;
+  }else{
+    i1 = pIter->aFirst[iOut*2].iFirst;
+    i2 = pIter->aFirst[iOut*2+1].iFirst;
+  }
+  p1 = &pIter->aSeg[i1];
+  p2 = &pIter->aSeg[i2];
+
+  pRes->bTermEq = 0;
+  if( p1->pLeaf==0 ){           /* If p1 is at EOF */
+    iRes = i2;
+  }else if( p2->pLeaf==0 ){     /* If p2 is at EOF */
+    iRes = i1;
+  }else{
+    int res = fts5BufferCompare(&p1->term, &p2->term);
+    if( res==0 ){
+      assert( i2>i1 );
+      assert( i2!=0 );
+      pRes->bTermEq = 1;
+      if( p1->iRowid==p2->iRowid ){
+        p1->bDel = p2->bDel;
+        return i2;
+      }
+      res = ((p1->iRowid > p2->iRowid)==pIter->bRev) ? -1 : +1;
+    }
+    assert( res!=0 );
+    if( res<0 ){
+      iRes = i1;
+    }else{
+      iRes = i2;
+    }
+  }
+
+  pRes->iFirst = (u16)iRes;
+  return 0;
+}
+
+/*
+** Move the seg-iter so that it points to the first rowid on page iLeafPgno.
+** It is an error if leaf iLeafPgno does not exist or contains no rowids.
+*/
+static void fts5SegIterGotoPage(
+  Fts5Index *p,                   /* FTS5 backend object */
+  Fts5SegIter *pIter,             /* Iterator to advance */
+  int iLeafPgno
+){
+  assert( iLeafPgno>pIter->iLeafPgno );
+
+  if( iLeafPgno>pIter->pSeg->pgnoLast ){
+    p->rc = FTS5_CORRUPT;
+  }else{
+    fts5DataRelease(pIter->pNextLeaf);
+    pIter->pNextLeaf = 0;
+    pIter->iLeafPgno = iLeafPgno-1;
+    fts5SegIterNextPage(p, pIter);
+    assert( p->rc!=SQLITE_OK || pIter->iLeafPgno==iLeafPgno );
+
+    if( p->rc==SQLITE_OK ){
+      int iOff;
+      u8 *a = pIter->pLeaf->p;
+      int n = pIter->pLeaf->szLeaf;
+
+      iOff = fts5LeafFirstRowidOff(pIter->pLeaf);
+      if( iOff<4 || iOff>=n ){
+        p->rc = FTS5_CORRUPT;
+      }else{
+        iOff += fts5GetVarint(&a[iOff], (u64*)&pIter->iRowid);
+        pIter->iLeafOffset = iOff;
+        fts5SegIterLoadNPos(p, pIter);
+      }
+    }
+  }
+}
+
+/*
+** Advance the iterator passed as the second argument until it is at or 
+** past rowid iFrom. Regardless of the value of iFrom, the iterator is
+** always advanced at least once.
+*/
+static void fts5SegIterNextFrom(
+  Fts5Index *p,                   /* FTS5 backend object */
+  Fts5SegIter *pIter,             /* Iterator to advance */
+  i64 iMatch                      /* Advance iterator at least this far */
+){
+  int bRev = (pIter->flags & FTS5_SEGITER_REVERSE);
+  Fts5DlidxIter *pDlidx = pIter->pDlidx;
+  int iLeafPgno = pIter->iLeafPgno;
+  int bMove = 1;
+
+  assert( pIter->flags & FTS5_SEGITER_ONETERM );
+  assert( pIter->pDlidx );
+  assert( pIter->pLeaf );
+
+  if( bRev==0 ){
+    while( !fts5DlidxIterEof(p, pDlidx) && iMatch>fts5DlidxIterRowid(pDlidx) ){
+      iLeafPgno = fts5DlidxIterPgno(pDlidx);
+      fts5DlidxIterNext(p, pDlidx);
+    }
+    assert_nc( iLeafPgno>=pIter->iLeafPgno || p->rc );
+    if( iLeafPgno>pIter->iLeafPgno ){
+      fts5SegIterGotoPage(p, pIter, iLeafPgno);
+      bMove = 0;
+    }
+  }else{
+    assert( pIter->pNextLeaf==0 );
+    assert( iMatch<pIter->iRowid );
+    while( !fts5DlidxIterEof(p, pDlidx) && iMatch<fts5DlidxIterRowid(pDlidx) ){
+      fts5DlidxIterPrev(p, pDlidx);
+    }
+    iLeafPgno = fts5DlidxIterPgno(pDlidx);
+
+    assert( fts5DlidxIterEof(p, pDlidx) || iLeafPgno<=pIter->iLeafPgno );
+
+    if( iLeafPgno<pIter->iLeafPgno ){
+      pIter->iLeafPgno = iLeafPgno+1;
+      fts5SegIterReverseNewPage(p, pIter);
+      bMove = 0;
+    }
+  }
+
+  do{
+    if( bMove && p->rc==SQLITE_OK ) pIter->xNext(p, pIter, 0);
+    if( pIter->pLeaf==0 ) break;
+    if( bRev==0 && pIter->iRowid>=iMatch ) break;
+    if( bRev!=0 && pIter->iRowid<=iMatch ) break;
+    bMove = 1;
+  }while( p->rc==SQLITE_OK );
+}
+
+
+/*
+** Free the iterator object passed as the second argument.
+*/
+static void fts5MultiIterFree(Fts5Iter *pIter){
+  if( pIter ){
+    int i;
+    for(i=0; i<pIter->nSeg; i++){
+      fts5SegIterClear(&pIter->aSeg[i]);
+    }
+    fts5StructureRelease(pIter->pStruct);
+    fts5BufferFree(&pIter->poslist);
+    sqlite3_free(pIter);
+  }
+}
+
+static void fts5MultiIterAdvanced(
+  Fts5Index *p,                   /* FTS5 backend to iterate within */
+  Fts5Iter *pIter,                /* Iterator to update aFirst[] array for */
+  int iChanged,                   /* Index of sub-iterator just advanced */
+  int iMinset                     /* Minimum entry in aFirst[] to set */
+){
+  int i;
+  for(i=(pIter->nSeg+iChanged)/2; i>=iMinset && p->rc==SQLITE_OK; i=i/2){
+    int iEq;
+    if( (iEq = fts5MultiIterDoCompare(pIter, i)) ){
+      Fts5SegIter *pSeg = &pIter->aSeg[iEq];
+      assert( p->rc==SQLITE_OK );
+      pSeg->xNext(p, pSeg, 0);
+      i = pIter->nSeg + iEq;
+    }
+  }
+}
+
+/*
+** Sub-iterator iChanged of iterator pIter has just been advanced. It still
+** points to the same term though - just a different rowid. This function
+** attempts to update the contents of the pIter->aFirst[] accordingly.
+** If it does so successfully, 0 is returned. Otherwise 1.
+**
+** If non-zero is returned, the caller should call fts5MultiIterAdvanced()
+** on the iterator instead. That function does the same as this one, except
+** that it deals with more complicated cases as well.
+*/ 
+static int fts5MultiIterAdvanceRowid(
+  Fts5Iter *pIter,                /* Iterator to update aFirst[] array for */
+  int iChanged,                   /* Index of sub-iterator just advanced */
+  Fts5SegIter **ppFirst
+){
+  Fts5SegIter *pNew = &pIter->aSeg[iChanged];
+
+  if( pNew->iRowid==pIter->iSwitchRowid
+   || (pNew->iRowid<pIter->iSwitchRowid)==pIter->bRev
+  ){
+    int i;
+    Fts5SegIter *pOther = &pIter->aSeg[iChanged ^ 0x0001];
+    pIter->iSwitchRowid = pIter->bRev ? SMALLEST_INT64 : LARGEST_INT64;
+    for(i=(pIter->nSeg+iChanged)/2; 1; i=i/2){
+      Fts5CResult *pRes = &pIter->aFirst[i];
+
+      assert( pNew->pLeaf );
+      assert( pRes->bTermEq==0 || pOther->pLeaf );
+
+      if( pRes->bTermEq ){
+        if( pNew->iRowid==pOther->iRowid ){
+          return 1;
+        }else if( (pOther->iRowid>pNew->iRowid)==pIter->bRev ){
+          pIter->iSwitchRowid = pOther->iRowid;
+          pNew = pOther;
+        }else if( (pOther->iRowid>pIter->iSwitchRowid)==pIter->bRev ){
+          pIter->iSwitchRowid = pOther->iRowid;
+        }
+      }
+      pRes->iFirst = (u16)(pNew - pIter->aSeg);
+      if( i==1 ) break;
+
+      pOther = &pIter->aSeg[ pIter->aFirst[i ^ 0x0001].iFirst ];
+    }
+  }
+
+  *ppFirst = pNew;
+  return 0;
+}
+
+/*
+** Set the pIter->bEof variable based on the state of the sub-iterators.
+*/
+static void fts5MultiIterSetEof(Fts5Iter *pIter){
+  Fts5SegIter *pSeg = &pIter->aSeg[ pIter->aFirst[1].iFirst ];
+  pIter->base.bEof = pSeg->pLeaf==0;
+  pIter->iSwitchRowid = pSeg->iRowid;
+}
+
+/*
+** Move the iterator to the next entry. 
+**
+** If an error occurs, an error code is left in Fts5Index.rc. It is not 
+** considered an error if the iterator reaches EOF, or if it is already at 
+** EOF when this function is called.
+*/
+static void fts5MultiIterNext(
+  Fts5Index *p, 
+  Fts5Iter *pIter,
+  int bFrom,                      /* True if argument iFrom is valid */
+  i64 iFrom                       /* Advance at least as far as this */
+){
+  int bUseFrom = bFrom;
+  assert( pIter->base.bEof==0 );
+  while( p->rc==SQLITE_OK ){
+    int iFirst = pIter->aFirst[1].iFirst;
+    int bNewTerm = 0;
+    Fts5SegIter *pSeg = &pIter->aSeg[iFirst];
+    assert( p->rc==SQLITE_OK );
+    if( bUseFrom && pSeg->pDlidx ){
+      fts5SegIterNextFrom(p, pSeg, iFrom);
+    }else{
+      pSeg->xNext(p, pSeg, &bNewTerm);
+    }
+
+    if( pSeg->pLeaf==0 || bNewTerm 
+     || fts5MultiIterAdvanceRowid(pIter, iFirst, &pSeg)
+    ){
+      fts5MultiIterAdvanced(p, pIter, iFirst, 1);
+      fts5MultiIterSetEof(pIter);
+      pSeg = &pIter->aSeg[pIter->aFirst[1].iFirst];
+      if( pSeg->pLeaf==0 ) return;
+    }
+
+    fts5AssertMultiIterSetup(p, pIter);
+    assert( pSeg==&pIter->aSeg[pIter->aFirst[1].iFirst] && pSeg->pLeaf );
+    if( pIter->bSkipEmpty==0 || pSeg->nPos ){
+      pIter->xSetOutputs(pIter, pSeg);
+      return;
+    }
+    bUseFrom = 0;
+  }
+}
+
+static void fts5MultiIterNext2(
+  Fts5Index *p, 
+  Fts5Iter *pIter,
+  int *pbNewTerm                  /* OUT: True if *might* be new term */
+){
+  assert( pIter->bSkipEmpty );
+  if( p->rc==SQLITE_OK ){
+    do {
+      int iFirst = pIter->aFirst[1].iFirst;
+      Fts5SegIter *pSeg = &pIter->aSeg[iFirst];
+      int bNewTerm = 0;
+
+      assert( p->rc==SQLITE_OK );
+      pSeg->xNext(p, pSeg, &bNewTerm);
+      if( pSeg->pLeaf==0 || bNewTerm 
+       || fts5MultiIterAdvanceRowid(pIter, iFirst, &pSeg)
+      ){
+        fts5MultiIterAdvanced(p, pIter, iFirst, 1);
+        fts5MultiIterSetEof(pIter);
+        *pbNewTerm = 1;
+      }else{
+        *pbNewTerm = 0;
+      }
+      fts5AssertMultiIterSetup(p, pIter);
+
+    }while( fts5MultiIterIsEmpty(p, pIter) );
+  }
+}
+
+static void fts5IterSetOutputs_Noop(Fts5Iter *pUnused1, Fts5SegIter *pUnused2){
+  UNUSED_PARAM2(pUnused1, pUnused2);
+}
+
+static Fts5Iter *fts5MultiIterAlloc(
+  Fts5Index *p,                   /* FTS5 backend to iterate within */
+  int nSeg
+){
+  Fts5Iter *pNew;
+  int nSlot;                      /* Power of two >= nSeg */
+
+  for(nSlot=2; nSlot<nSeg; nSlot=nSlot*2);
+  pNew = fts5IdxMalloc(p, 
+      sizeof(Fts5Iter) +                  /* pNew */
+      sizeof(Fts5SegIter) * (nSlot-1) +   /* pNew->aSeg[] */
+      sizeof(Fts5CResult) * nSlot         /* pNew->aFirst[] */
+  );
+  if( pNew ){
+    pNew->nSeg = nSlot;
+    pNew->aFirst = (Fts5CResult*)&pNew->aSeg[nSlot];
+    pNew->pIndex = p;
+    pNew->xSetOutputs = fts5IterSetOutputs_Noop;
+  }
+  return pNew;
+}
+
+static void fts5PoslistCallback(
+  Fts5Index *pUnused, 
+  void *pContext, 
+  const u8 *pChunk, int nChunk
+){
+  UNUSED_PARAM(pUnused);
+  assert_nc( nChunk>=0 );
+  if( nChunk>0 ){
+    fts5BufferSafeAppendBlob((Fts5Buffer*)pContext, pChunk, nChunk);
+  }
+}
+
+typedef struct PoslistCallbackCtx PoslistCallbackCtx;
+struct PoslistCallbackCtx {
+  Fts5Buffer *pBuf;               /* Append to this buffer */
+  Fts5Colset *pColset;            /* Restrict matches to this column */
+  int eState;                     /* See above */
+};
+
+typedef struct PoslistOffsetsCtx PoslistOffsetsCtx;
+struct PoslistOffsetsCtx {
+  Fts5Buffer *pBuf;               /* Append to this buffer */
+  Fts5Colset *pColset;            /* Restrict matches to this column */
+  int iRead;
+  int iWrite;
+};
+
+/*
+** TODO: Make this more efficient!
+*/
+static int fts5IndexColsetTest(Fts5Colset *pColset, int iCol){
+  int i;
+  for(i=0; i<pColset->nCol; i++){
+    if( pColset->aiCol[i]==iCol ) return 1;
+  }
+  return 0;
+}
+
+static void fts5PoslistOffsetsCallback(
+  Fts5Index *pUnused, 
+  void *pContext, 
+  const u8 *pChunk, int nChunk
+){
+  PoslistOffsetsCtx *pCtx = (PoslistOffsetsCtx*)pContext;
+  UNUSED_PARAM(pUnused);
+  assert_nc( nChunk>=0 );
+  if( nChunk>0 ){
+    int i = 0;
+    while( i<nChunk ){
+      int iVal;
+      i += fts5GetVarint32(&pChunk[i], iVal);
+      iVal += pCtx->iRead - 2;
+      pCtx->iRead = iVal;
+      if( fts5IndexColsetTest(pCtx->pColset, iVal) ){
+        fts5BufferSafeAppendVarint(pCtx->pBuf, iVal + 2 - pCtx->iWrite);
+        pCtx->iWrite = iVal;
+      }
+    }
+  }
+}
+
+static void fts5PoslistFilterCallback(
+  Fts5Index *pUnused,
+  void *pContext, 
+  const u8 *pChunk, int nChunk
+){
+  PoslistCallbackCtx *pCtx = (PoslistCallbackCtx*)pContext;
+  UNUSED_PARAM(pUnused);
+  assert_nc( nChunk>=0 );
+  if( nChunk>0 ){
+    /* Search through to find the first varint with value 1. This is the
+    ** start of the next columns hits. */
+    int i = 0;
+    int iStart = 0;
+
+    if( pCtx->eState==2 ){
+      int iCol;
+      fts5FastGetVarint32(pChunk, i, iCol);
+      if( fts5IndexColsetTest(pCtx->pColset, iCol) ){
+        pCtx->eState = 1;
+        fts5BufferSafeAppendVarint(pCtx->pBuf, 1);
+      }else{
+        pCtx->eState = 0;
+      }
+    }
+
+    do {
+      while( i<nChunk && pChunk[i]!=0x01 ){
+        while( pChunk[i] & 0x80 ) i++;
+        i++;
+      }
+      if( pCtx->eState ){
+        fts5BufferSafeAppendBlob(pCtx->pBuf, &pChunk[iStart], i-iStart);
+      }
+      if( i<nChunk ){
+        int iCol;
+        iStart = i;
+        i++;
+        if( i>=nChunk ){
+          pCtx->eState = 2;
+        }else{
+          fts5FastGetVarint32(pChunk, i, iCol);
+          pCtx->eState = fts5IndexColsetTest(pCtx->pColset, iCol);
+          if( pCtx->eState ){
+            fts5BufferSafeAppendBlob(pCtx->pBuf, &pChunk[iStart], i-iStart);
+            iStart = i;
+          }
+        }
+      }
+    }while( i<nChunk );
+  }
+}
+
+static void fts5ChunkIterate(
+  Fts5Index *p,                   /* Index object */
+  Fts5SegIter *pSeg,              /* Poslist of this iterator */
+  void *pCtx,                     /* Context pointer for xChunk callback */
+  void (*xChunk)(Fts5Index*, void*, const u8*, int)
+){
+  int nRem = pSeg->nPos;          /* Number of bytes still to come */
+  Fts5Data *pData = 0;
+  u8 *pChunk = &pSeg->pLeaf->p[pSeg->iLeafOffset];
+  int nChunk = MIN(nRem, pSeg->pLeaf->szLeaf - pSeg->iLeafOffset);
+  int pgno = pSeg->iLeafPgno;
+  int pgnoSave = 0;
+
+  /* This function does notmwork with detail=none databases. */
+  assert( p->pConfig->eDetail!=FTS5_DETAIL_NONE );
+
+  if( (pSeg->flags & FTS5_SEGITER_REVERSE)==0 ){
+    pgnoSave = pgno+1;
+  }
+
+  while( 1 ){
+    xChunk(p, pCtx, pChunk, nChunk);
+    nRem -= nChunk;
+    fts5DataRelease(pData);
+    if( nRem<=0 ){
+      break;
+    }else{
+      pgno++;
+      pData = fts5DataRead(p, FTS5_SEGMENT_ROWID(pSeg->pSeg->iSegid, pgno));
+      if( pData==0 ) break;
+      pChunk = &pData->p[4];
+      nChunk = MIN(nRem, pData->szLeaf - 4);
+      if( pgno==pgnoSave ){
+        assert( pSeg->pNextLeaf==0 );
+        pSeg->pNextLeaf = pData;
+        pData = 0;
+      }
+    }
+  }
+}
+
+/*
+** Iterator pIter currently points to a valid entry (not EOF). This
+** function appends the position list data for the current entry to
+** buffer pBuf. It does not make a copy of the position-list size
+** field.
+*/
+static void fts5SegiterPoslist(
+  Fts5Index *p,
+  Fts5SegIter *pSeg,
+  Fts5Colset *pColset,
+  Fts5Buffer *pBuf
+){
+  if( 0==fts5BufferGrow(&p->rc, pBuf, pSeg->nPos) ){
+    if( pColset==0 ){
+      fts5ChunkIterate(p, pSeg, (void*)pBuf, fts5PoslistCallback);
+    }else{
+      if( p->pConfig->eDetail==FTS5_DETAIL_FULL ){
+        PoslistCallbackCtx sCtx;
+        sCtx.pBuf = pBuf;
+        sCtx.pColset = pColset;
+        sCtx.eState = fts5IndexColsetTest(pColset, 0);
+        assert( sCtx.eState==0 || sCtx.eState==1 );
+        fts5ChunkIterate(p, pSeg, (void*)&sCtx, fts5PoslistFilterCallback);
+      }else{
+        PoslistOffsetsCtx sCtx;
+        memset(&sCtx, 0, sizeof(sCtx));
+        sCtx.pBuf = pBuf;
+        sCtx.pColset = pColset;
+        fts5ChunkIterate(p, pSeg, (void*)&sCtx, fts5PoslistOffsetsCallback);
+      }
+    }
+  }
+}
+
+/*
+** IN/OUT parameter (*pa) points to a position list n bytes in size. If
+** the position list contains entries for column iCol, then (*pa) is set
+** to point to the sub-position-list for that column and the number of
+** bytes in it returned. Or, if the argument position list does not
+** contain any entries for column iCol, return 0.
+*/
+static int fts5IndexExtractCol(
+  const u8 **pa,                  /* IN/OUT: Pointer to poslist */
+  int n,                          /* IN: Size of poslist in bytes */
+  int iCol                        /* Column to extract from poslist */
+){
+  int iCurrent = 0;               /* Anything before the first 0x01 is col 0 */
+  const u8 *p = *pa;
+  const u8 *pEnd = &p[n];         /* One byte past end of position list */
+
+  while( iCol>iCurrent ){
+    /* Advance pointer p until it points to pEnd or an 0x01 byte that is
+    ** not part of a varint. Note that it is not possible for a negative
+    ** or extremely large varint to occur within an uncorrupted position 
+    ** list. So the last byte of each varint may be assumed to have a clear
+    ** 0x80 bit.  */
+    while( *p!=0x01 ){
+      while( *p++ & 0x80 );
+      if( p>=pEnd ) return 0;
+    }
+    *pa = p++;
+    iCurrent = *p++;
+    if( iCurrent & 0x80 ){
+      p--;
+      p += fts5GetVarint32(p, iCurrent);
+    }
+  }
+  if( iCol!=iCurrent ) return 0;
+
+  /* Advance pointer p until it points to pEnd or an 0x01 byte that is
+  ** not part of a varint */
+  while( p<pEnd && *p!=0x01 ){
+    while( *p++ & 0x80 );
+  }
+
+  return p - (*pa);
+}
+
+static int fts5IndexExtractColset (
+  Fts5Colset *pColset,            /* Colset to filter on */
+  const u8 *pPos, int nPos,       /* Position list */
+  Fts5Buffer *pBuf                /* Output buffer */
+){
+  int rc = SQLITE_OK;
+  int i;
+
+  fts5BufferZero(pBuf);
+  for(i=0; i<pColset->nCol; i++){
+    const u8 *pSub = pPos;
+    int nSub = fts5IndexExtractCol(&pSub, nPos, pColset->aiCol[i]);
+    if( nSub ){
+      fts5BufferAppendBlob(&rc, pBuf, nSub, pSub);
+    }
+  }
+  return rc;
+}
+
+/*
+** xSetOutputs callback used by detail=none tables.
+*/
+static void fts5IterSetOutputs_None(Fts5Iter *pIter, Fts5SegIter *pSeg){
+  assert( pIter->pIndex->pConfig->eDetail==FTS5_DETAIL_NONE );
+  pIter->base.iRowid = pSeg->iRowid;
+  pIter->base.nData = pSeg->nPos;
+}
+
+/*
+** xSetOutputs callback used by detail=full and detail=col tables when no
+** column filters are specified.
+*/
+static void fts5IterSetOutputs_Nocolset(Fts5Iter *pIter, Fts5SegIter *pSeg){
+  pIter->base.iRowid = pSeg->iRowid;
+  pIter->base.nData = pSeg->nPos;
+
+  assert( pIter->pIndex->pConfig->eDetail!=FTS5_DETAIL_NONE );
+  assert( pIter->pColset==0 );
+
+  if( pSeg->iLeafOffset+pSeg->nPos<=pSeg->pLeaf->szLeaf ){
+    /* All data is stored on the current page. Populate the output 
+    ** variables to point into the body of the page object. */
+    pIter->base.pData = &pSeg->pLeaf->p[pSeg->iLeafOffset];
+  }else{
+    /* The data is distributed over two or more pages. Copy it into the
+    ** Fts5Iter.poslist buffer and then set the output pointer to point
+    ** to this buffer.  */
+    fts5BufferZero(&pIter->poslist);
+    fts5SegiterPoslist(pIter->pIndex, pSeg, 0, &pIter->poslist);
+    pIter->base.pData = pIter->poslist.p;
+  }
+}
+
+/*
+** xSetOutputs callback used when the Fts5Colset object has nCol==0 (match
+** against no columns at all).
+*/
+static void fts5IterSetOutputs_ZeroColset(Fts5Iter *pIter, Fts5SegIter *pSeg){
+  UNUSED_PARAM(pSeg);
+  pIter->base.nData = 0;
+}
+
+/*
+** xSetOutputs callback used by detail=col when there is a column filter
+** and there are 100 or more columns. Also called as a fallback from
+** fts5IterSetOutputs_Col100 if the column-list spans more than one page.
+*/
+static void fts5IterSetOutputs_Col(Fts5Iter *pIter, Fts5SegIter *pSeg){
+  fts5BufferZero(&pIter->poslist);
+  fts5SegiterPoslist(pIter->pIndex, pSeg, pIter->pColset, &pIter->poslist);
+  pIter->base.iRowid = pSeg->iRowid;
+  pIter->base.pData = pIter->poslist.p;
+  pIter->base.nData = pIter->poslist.n;
+}
+
+/*
+** xSetOutputs callback used when: 
+**
+**   * detail=col,
+**   * there is a column filter, and
+**   * the table contains 100 or fewer columns. 
+**
+** The last point is to ensure all column numbers are stored as 
+** single-byte varints.
+*/
+static void fts5IterSetOutputs_Col100(Fts5Iter *pIter, Fts5SegIter *pSeg){
+
+  assert( pIter->pIndex->pConfig->eDetail==FTS5_DETAIL_COLUMNS );
+  assert( pIter->pColset );
+
+  if( pSeg->iLeafOffset+pSeg->nPos>pSeg->pLeaf->szLeaf ){
+    fts5IterSetOutputs_Col(pIter, pSeg);
+  }else{
+    u8 *a = (u8*)&pSeg->pLeaf->p[pSeg->iLeafOffset];
+    u8 *pEnd = (u8*)&a[pSeg->nPos]; 
+    int iPrev = 0;
+    int *aiCol = pIter->pColset->aiCol;
+    int *aiColEnd = &aiCol[pIter->pColset->nCol];
+
+    u8 *aOut = pIter->poslist.p;
+    int iPrevOut = 0;
+
+    pIter->base.iRowid = pSeg->iRowid;
+
+    while( a<pEnd ){
+      iPrev += (int)a++[0] - 2;
+      while( *aiCol<iPrev ){
+        aiCol++;
+        if( aiCol==aiColEnd ) goto setoutputs_col_out;
+      }
+      if( *aiCol==iPrev ){
+        *aOut++ = (u8)((iPrev - iPrevOut) + 2);
+        iPrevOut = iPrev;
+      }
+    }
+
+setoutputs_col_out:
+    pIter->base.pData = pIter->poslist.p;
+    pIter->base.nData = aOut - pIter->poslist.p;
+  }
+}
+
+/*
+** xSetOutputs callback used by detail=full when there is a column filter.
+*/
+static void fts5IterSetOutputs_Full(Fts5Iter *pIter, Fts5SegIter *pSeg){
+  Fts5Colset *pColset = pIter->pColset;
+  pIter->base.iRowid = pSeg->iRowid;
+
+  assert( pIter->pIndex->pConfig->eDetail==FTS5_DETAIL_FULL );
+  assert( pColset );
+
+  if( pSeg->iLeafOffset+pSeg->nPos<=pSeg->pLeaf->szLeaf ){
+    /* All data is stored on the current page. Populate the output 
+    ** variables to point into the body of the page object. */
+    const u8 *a = &pSeg->pLeaf->p[pSeg->iLeafOffset];
+    if( pColset->nCol==1 ){
+      pIter->base.nData = fts5IndexExtractCol(&a, pSeg->nPos,pColset->aiCol[0]);
+      pIter->base.pData = a;
+    }else{
+      fts5BufferZero(&pIter->poslist);
+      fts5IndexExtractColset(pColset, a, pSeg->nPos, &pIter->poslist);
+      pIter->base.pData = pIter->poslist.p;
+      pIter->base.nData = pIter->poslist.n;
+    }
+  }else{
+    /* The data is distributed over two or more pages. Copy it into the
+    ** Fts5Iter.poslist buffer and then set the output pointer to point
+    ** to this buffer.  */
+    fts5BufferZero(&pIter->poslist);
+    fts5SegiterPoslist(pIter->pIndex, pSeg, pColset, &pIter->poslist);
+    pIter->base.pData = pIter->poslist.p;
+    pIter->base.nData = pIter->poslist.n;
+  }
+}
+
+static void fts5IterSetOutputCb(int *pRc, Fts5Iter *pIter){
+  if( *pRc==SQLITE_OK ){
+    Fts5Config *pConfig = pIter->pIndex->pConfig;
+    if( pConfig->eDetail==FTS5_DETAIL_NONE ){
+      pIter->xSetOutputs = fts5IterSetOutputs_None;
+    }
+
+    else if( pIter->pColset==0 ){
+      pIter->xSetOutputs = fts5IterSetOutputs_Nocolset;
+    }
+
+    else if( pIter->pColset->nCol==0 ){
+      pIter->xSetOutputs = fts5IterSetOutputs_ZeroColset;
+    }
+
+    else if( pConfig->eDetail==FTS5_DETAIL_FULL ){
+      pIter->xSetOutputs = fts5IterSetOutputs_Full;
+    }
+
+    else{
+      assert( pConfig->eDetail==FTS5_DETAIL_COLUMNS );
+      if( pConfig->nCol<=100 ){
+        pIter->xSetOutputs = fts5IterSetOutputs_Col100;
+        sqlite3Fts5BufferSize(pRc, &pIter->poslist, pConfig->nCol);
+      }else{
+        pIter->xSetOutputs = fts5IterSetOutputs_Col;
+      }
+    }
+  }
+}
+
+
+/*
+** Allocate a new Fts5Iter object.
+**
+** The new object will be used to iterate through data in structure pStruct.
+** If iLevel is -ve, then all data in all segments is merged. Or, if iLevel
+** is zero or greater, data from the first nSegment segments on level iLevel
+** is merged.
+**
+** The iterator initially points to the first term/rowid entry in the 
+** iterated data.
+*/
+static void fts5MultiIterNew(
+  Fts5Index *p,                   /* FTS5 backend to iterate within */
+  Fts5Structure *pStruct,         /* Structure of specific index */
+  int flags,                      /* FTS5INDEX_QUERY_XXX flags */
+  Fts5Colset *pColset,            /* Colset to filter on (or NULL) */
+  const u8 *pTerm, int nTerm,     /* Term to seek to (or NULL/0) */
+  int iLevel,                     /* Level to iterate (-1 for all) */
+  int nSegment,                   /* Number of segments to merge (iLevel>=0) */
+  Fts5Iter **ppOut                /* New object */
+){
+  int nSeg = 0;                   /* Number of segment-iters in use */
+  int iIter = 0;                  /* */
+  int iSeg;                       /* Used to iterate through segments */
+  Fts5StructureLevel *pLvl;
+  Fts5Iter *pNew;
+
+  assert( (pTerm==0 && nTerm==0) || iLevel<0 );
+
+  /* Allocate space for the new multi-seg-iterator. */
+  if( p->rc==SQLITE_OK ){
+    if( iLevel<0 ){
+      assert( pStruct->nSegment==fts5StructureCountSegments(pStruct) );
+      nSeg = pStruct->nSegment;
+      nSeg += (p->pHash ? 1 : 0);
+    }else{
+      nSeg = MIN(pStruct->aLevel[iLevel].nSeg, nSegment);
+    }
+  }
+  *ppOut = pNew = fts5MultiIterAlloc(p, nSeg);
+  if( pNew==0 ) return;
+  pNew->bRev = (0!=(flags & FTS5INDEX_QUERY_DESC));
+  pNew->bSkipEmpty = (0!=(flags & FTS5INDEX_QUERY_SKIPEMPTY));
+  pNew->pStruct = pStruct;
+  pNew->pColset = pColset;
+  fts5StructureRef(pStruct);
+  if( (flags & FTS5INDEX_QUERY_NOOUTPUT)==0 ){
+    fts5IterSetOutputCb(&p->rc, pNew);
+  }
+
+  /* Initialize each of the component segment iterators. */
+  if( p->rc==SQLITE_OK ){
+    if( iLevel<0 ){
+      Fts5StructureLevel *pEnd = &pStruct->aLevel[pStruct->nLevel];
+      if( p->pHash ){
+        /* Add a segment iterator for the current contents of the hash table. */
+        Fts5SegIter *pIter = &pNew->aSeg[iIter++];
+        fts5SegIterHashInit(p, pTerm, nTerm, flags, pIter);
+      }
+      for(pLvl=&pStruct->aLevel[0]; pLvl<pEnd; pLvl++){
+        for(iSeg=pLvl->nSeg-1; iSeg>=0; iSeg--){
+          Fts5StructureSegment *pSeg = &pLvl->aSeg[iSeg];
+          Fts5SegIter *pIter = &pNew->aSeg[iIter++];
+          if( pTerm==0 ){
+            fts5SegIterInit(p, pSeg, pIter);
+          }else{
+            fts5SegIterSeekInit(p, pTerm, nTerm, flags, pSeg, pIter);
+          }
+        }
+      }
+    }else{
+      pLvl = &pStruct->aLevel[iLevel];
+      for(iSeg=nSeg-1; iSeg>=0; iSeg--){
+        fts5SegIterInit(p, &pLvl->aSeg[iSeg], &pNew->aSeg[iIter++]);
+      }
+    }
+    assert( iIter==nSeg );
+  }
+
+  /* If the above was successful, each component iterators now points 
+  ** to the first entry in its segment. In this case initialize the 
+  ** aFirst[] array. Or, if an error has occurred, free the iterator
+  ** object and set the output variable to NULL.  */
+  if( p->rc==SQLITE_OK ){
+    for(iIter=pNew->nSeg-1; iIter>0; iIter--){
+      int iEq;
+      if( (iEq = fts5MultiIterDoCompare(pNew, iIter)) ){
+        Fts5SegIter *pSeg = &pNew->aSeg[iEq];
+        if( p->rc==SQLITE_OK ) pSeg->xNext(p, pSeg, 0);
+        fts5MultiIterAdvanced(p, pNew, iEq, iIter);
+      }
+    }
+    fts5MultiIterSetEof(pNew);
+    fts5AssertMultiIterSetup(p, pNew);
+
+    if( pNew->bSkipEmpty && fts5MultiIterIsEmpty(p, pNew) ){
+      fts5MultiIterNext(p, pNew, 0, 0);
+    }else if( pNew->base.bEof==0 ){
+      Fts5SegIter *pSeg = &pNew->aSeg[pNew->aFirst[1].iFirst];
+      pNew->xSetOutputs(pNew, pSeg);
+    }
+
+  }else{
+    fts5MultiIterFree(pNew);
+    *ppOut = 0;
+  }
+}
+
+/*
+** Create an Fts5Iter that iterates through the doclist provided
+** as the second argument.
+*/
+static void fts5MultiIterNew2(
+  Fts5Index *p,                   /* FTS5 backend to iterate within */
+  Fts5Data *pData,                /* Doclist to iterate through */
+  int bDesc,                      /* True for descending rowid order */
+  Fts5Iter **ppOut                /* New object */
+){
+  Fts5Iter *pNew;
+  pNew = fts5MultiIterAlloc(p, 2);
+  if( pNew ){
+    Fts5SegIter *pIter = &pNew->aSeg[1];
+
+    pIter->flags = FTS5_SEGITER_ONETERM;
+    if( pData->szLeaf>0 ){
+      pIter->pLeaf = pData;
+      pIter->iLeafOffset = fts5GetVarint(pData->p, (u64*)&pIter->iRowid);
+      pIter->iEndofDoclist = pData->nn;
+      pNew->aFirst[1].iFirst = 1;
+      if( bDesc ){
+        pNew->bRev = 1;
+        pIter->flags |= FTS5_SEGITER_REVERSE;
+        fts5SegIterReverseInitPage(p, pIter);
+      }else{
+        fts5SegIterLoadNPos(p, pIter);
+      }
+      pData = 0;
+    }else{
+      pNew->base.bEof = 1;
+    }
+    fts5SegIterSetNext(p, pIter);
+
+    *ppOut = pNew;
+  }
+
+  fts5DataRelease(pData);
+}
+
+/*
+** Return true if the iterator is at EOF or if an error has occurred. 
+** False otherwise.
+*/
+static int fts5MultiIterEof(Fts5Index *p, Fts5Iter *pIter){
+  assert( p->rc 
+      || (pIter->aSeg[ pIter->aFirst[1].iFirst ].pLeaf==0)==pIter->base.bEof 
+  );
+  return (p->rc || pIter->base.bEof);
+}
+
+/*
+** Return the rowid of the entry that the iterator currently points
+** to. If the iterator points to EOF when this function is called the
+** results are undefined.
+*/
+static i64 fts5MultiIterRowid(Fts5Iter *pIter){
+  assert( pIter->aSeg[ pIter->aFirst[1].iFirst ].pLeaf );
+  return pIter->aSeg[ pIter->aFirst[1].iFirst ].iRowid;
+}
+
+/*
+** Move the iterator to the next entry at or following iMatch.
+*/
+static void fts5MultiIterNextFrom(
+  Fts5Index *p, 
+  Fts5Iter *pIter, 
+  i64 iMatch
+){
+  while( 1 ){
+    i64 iRowid;
+    fts5MultiIterNext(p, pIter, 1, iMatch);
+    if( fts5MultiIterEof(p, pIter) ) break;
+    iRowid = fts5MultiIterRowid(pIter);
+    if( pIter->bRev==0 && iRowid>=iMatch ) break;
+    if( pIter->bRev!=0 && iRowid<=iMatch ) break;
+  }
+}
+
+/*
+** Return a pointer to a buffer containing the term associated with the 
+** entry that the iterator currently points to.
+*/
+static const u8 *fts5MultiIterTerm(Fts5Iter *pIter, int *pn){
+  Fts5SegIter *p = &pIter->aSeg[ pIter->aFirst[1].iFirst ];
+  *pn = p->term.n;
+  return p->term.p;
+}
+
+/*
+** Allocate a new segment-id for the structure pStruct. The new segment
+** id must be between 1 and 65335 inclusive, and must not be used by 
+** any currently existing segment. If a free segment id cannot be found,
+** SQLITE_FULL is returned.
+**
+** If an error has already occurred, this function is a no-op. 0 is 
+** returned in this case.
+*/
+static int fts5AllocateSegid(Fts5Index *p, Fts5Structure *pStruct){
+  int iSegid = 0;
+
+  if( p->rc==SQLITE_OK ){
+    if( pStruct->nSegment>=FTS5_MAX_SEGMENT ){
+      p->rc = SQLITE_FULL;
+    }else{
+      /* FTS5_MAX_SEGMENT is currently defined as 2000. So the following
+      ** array is 63 elements, or 252 bytes, in size.  */
+      u32 aUsed[(FTS5_MAX_SEGMENT+31) / 32];
+      int iLvl, iSeg;
+      int i;
+      u32 mask;
+      memset(aUsed, 0, sizeof(aUsed));
+      for(iLvl=0; iLvl<pStruct->nLevel; iLvl++){
+        for(iSeg=0; iSeg<pStruct->aLevel[iLvl].nSeg; iSeg++){
+          int iId = pStruct->aLevel[iLvl].aSeg[iSeg].iSegid;
+          if( iId<=FTS5_MAX_SEGMENT ){
+            aUsed[(iId-1) / 32] |= 1 << ((iId-1) % 32);
+          }
+        }
+      }
+
+      for(i=0; aUsed[i]==0xFFFFFFFF; i++);
+      mask = aUsed[i];
+      for(iSegid=0; mask & (1 << iSegid); iSegid++);
+      iSegid += 1 + i*32;
+
+#ifdef SQLITE_DEBUG
+      for(iLvl=0; iLvl<pStruct->nLevel; iLvl++){
+        for(iSeg=0; iSeg<pStruct->aLevel[iLvl].nSeg; iSeg++){
+          assert( iSegid!=pStruct->aLevel[iLvl].aSeg[iSeg].iSegid );
+        }
+      }
+      assert( iSegid>0 && iSegid<=FTS5_MAX_SEGMENT );
+
+      {
+        sqlite3_stmt *pIdxSelect = fts5IdxSelectStmt(p);
+        if( p->rc==SQLITE_OK ){
+          u8 aBlob[2] = {0xff, 0xff};
+          sqlite3_bind_int(pIdxSelect, 1, iSegid);
+          sqlite3_bind_blob(pIdxSelect, 2, aBlob, 2, SQLITE_STATIC);
+          assert( sqlite3_step(pIdxSelect)!=SQLITE_ROW );
+          p->rc = sqlite3_reset(pIdxSelect);
+        }
+      }
+#endif
+    }
+  }
+
+  return iSegid;
+}
+
+/*
+** Discard all data currently cached in the hash-tables.
+*/
+static void fts5IndexDiscardData(Fts5Index *p){
+  assert( p->pHash || p->nPendingData==0 );
+  if( p->pHash ){
+    sqlite3Fts5HashClear(p->pHash);
+    p->nPendingData = 0;
+  }
+}
+
+/*
+** Return the size of the prefix, in bytes, that buffer 
+** (pNew/<length-unknown>) shares with buffer (pOld/nOld).
+**
+** Buffer (pNew/<length-unknown>) is guaranteed to be greater 
+** than buffer (pOld/nOld).
+*/
+static int fts5PrefixCompress(int nOld, const u8 *pOld, const u8 *pNew){
+  int i;
+  for(i=0; i<nOld; i++){
+    if( pOld[i]!=pNew[i] ) break;
+  }
+  return i;
+}
+
+static void fts5WriteDlidxClear(
+  Fts5Index *p, 
+  Fts5SegWriter *pWriter,
+  int bFlush                      /* If true, write dlidx to disk */
+){
+  int i;
+  assert( bFlush==0 || (pWriter->nDlidx>0 && pWriter->aDlidx[0].buf.n>0) );
+  for(i=0; i<pWriter->nDlidx; i++){
+    Fts5DlidxWriter *pDlidx = &pWriter->aDlidx[i];
+    if( pDlidx->buf.n==0 ) break;
+    if( bFlush ){
+      assert( pDlidx->pgno!=0 );
+      fts5DataWrite(p, 
+          FTS5_DLIDX_ROWID(pWriter->iSegid, i, pDlidx->pgno),
+          pDlidx->buf.p, pDlidx->buf.n
+      );
+    }
+    sqlite3Fts5BufferZero(&pDlidx->buf);
+    pDlidx->bPrevValid = 0;
+  }
+}
+
+/*
+** Grow the pWriter->aDlidx[] array to at least nLvl elements in size.
+** Any new array elements are zeroed before returning.
+*/
+static int fts5WriteDlidxGrow(
+  Fts5Index *p,
+  Fts5SegWriter *pWriter,
+  int nLvl
+){
+  if( p->rc==SQLITE_OK && nLvl>=pWriter->nDlidx ){
+    Fts5DlidxWriter *aDlidx = (Fts5DlidxWriter*)sqlite3_realloc(
+        pWriter->aDlidx, sizeof(Fts5DlidxWriter) * nLvl
+    );
+    if( aDlidx==0 ){
+      p->rc = SQLITE_NOMEM;
+    }else{
+      int nByte = sizeof(Fts5DlidxWriter) * (nLvl - pWriter->nDlidx);
+      memset(&aDlidx[pWriter->nDlidx], 0, nByte);
+      pWriter->aDlidx = aDlidx;
+      pWriter->nDlidx = nLvl;
+    }
+  }
+  return p->rc;
+}
+
+/*
+** If the current doclist-index accumulating in pWriter->aDlidx[] is large
+** enough, flush it to disk and return 1. Otherwise discard it and return
+** zero.
+*/
+static int fts5WriteFlushDlidx(Fts5Index *p, Fts5SegWriter *pWriter){
+  int bFlag = 0;
+
+  /* If there were FTS5_MIN_DLIDX_SIZE or more empty leaf pages written
+  ** to the database, also write the doclist-index to disk.  */
+  if( pWriter->aDlidx[0].buf.n>0 && pWriter->nEmpty>=FTS5_MIN_DLIDX_SIZE ){
+    bFlag = 1;
+  }
+  fts5WriteDlidxClear(p, pWriter, bFlag);
+  pWriter->nEmpty = 0;
+  return bFlag;
+}
+
+/*
+** This function is called whenever processing of the doclist for the 
+** last term on leaf page (pWriter->iBtPage) is completed. 
+**
+** The doclist-index for that term is currently stored in-memory within the
+** Fts5SegWriter.aDlidx[] array. If it is large enough, this function
+** writes it out to disk. Or, if it is too small to bother with, discards
+** it.
+**
+** Fts5SegWriter.btterm currently contains the first term on page iBtPage.
+*/
+static void fts5WriteFlushBtree(Fts5Index *p, Fts5SegWriter *pWriter){
+  int bFlag;
+
+  assert( pWriter->iBtPage || pWriter->nEmpty==0 );
+  if( pWriter->iBtPage==0 ) return;
+  bFlag = fts5WriteFlushDlidx(p, pWriter);
+
+  if( p->rc==SQLITE_OK ){
+    const char *z = (pWriter->btterm.n>0?(const char*)pWriter->btterm.p:"");
+    /* The following was already done in fts5WriteInit(): */
+    /* sqlite3_bind_int(p->pIdxWriter, 1, pWriter->iSegid); */
+    sqlite3_bind_blob(p->pIdxWriter, 2, z, pWriter->btterm.n, SQLITE_STATIC);
+    sqlite3_bind_int64(p->pIdxWriter, 3, bFlag + ((i64)pWriter->iBtPage<<1));
+    sqlite3_step(p->pIdxWriter);
+    p->rc = sqlite3_reset(p->pIdxWriter);
+  }
+  pWriter->iBtPage = 0;
+}
+
+/*
+** This is called once for each leaf page except the first that contains
+** at least one term. Argument (nTerm/pTerm) is the split-key - a term that
+** is larger than all terms written to earlier leaves, and equal to or
+** smaller than the first term on the new leaf.
+**
+** If an error occurs, an error code is left in Fts5Index.rc. If an error
+** has already occurred when this function is called, it is a no-op.
+*/
+static void fts5WriteBtreeTerm(
+  Fts5Index *p,                   /* FTS5 backend object */
+  Fts5SegWriter *pWriter,         /* Writer object */
+  int nTerm, const u8 *pTerm      /* First term on new page */
+){
+  fts5WriteFlushBtree(p, pWriter);
+  fts5BufferSet(&p->rc, &pWriter->btterm, nTerm, pTerm);
+  pWriter->iBtPage = pWriter->writer.pgno;
+}
+
+/*
+** This function is called when flushing a leaf page that contains no
+** terms at all to disk.
+*/
+static void fts5WriteBtreeNoTerm(
+  Fts5Index *p,                   /* FTS5 backend object */
+  Fts5SegWriter *pWriter          /* Writer object */
+){
+  /* If there were no rowids on the leaf page either and the doclist-index
+  ** has already been started, append an 0x00 byte to it.  */
+  if( pWriter->bFirstRowidInPage && pWriter->aDlidx[0].buf.n>0 ){
+    Fts5DlidxWriter *pDlidx = &pWriter->aDlidx[0];
+    assert( pDlidx->bPrevValid );
+    sqlite3Fts5BufferAppendVarint(&p->rc, &pDlidx->buf, 0);
+  }
+
+  /* Increment the "number of sequential leaves without a term" counter. */
+  pWriter->nEmpty++;
+}
+
+static i64 fts5DlidxExtractFirstRowid(Fts5Buffer *pBuf){
+  i64 iRowid;
+  int iOff;
+
+  iOff = 1 + fts5GetVarint(&pBuf->p[1], (u64*)&iRowid);
+  fts5GetVarint(&pBuf->p[iOff], (u64*)&iRowid);
+  return iRowid;
+}
+
+/*
+** Rowid iRowid has just been appended to the current leaf page. It is the
+** first on the page. This function appends an appropriate entry to the current
+** doclist-index.
+*/
+static void fts5WriteDlidxAppend(
+  Fts5Index *p, 
+  Fts5SegWriter *pWriter, 
+  i64 iRowid
+){
+  int i;
+  int bDone = 0;
+
+  for(i=0; p->rc==SQLITE_OK && bDone==0; i++){
+    i64 iVal;
+    Fts5DlidxWriter *pDlidx = &pWriter->aDlidx[i];
+
+    if( pDlidx->buf.n>=p->pConfig->pgsz ){
+      /* The current doclist-index page is full. Write it to disk and push
+      ** a copy of iRowid (which will become the first rowid on the next
+      ** doclist-index leaf page) up into the next level of the b-tree 
+      ** hierarchy. If the node being flushed is currently the root node,
+      ** also push its first rowid upwards. */
+      pDlidx->buf.p[0] = 0x01;    /* Not the root node */
+      fts5DataWrite(p, 
+          FTS5_DLIDX_ROWID(pWriter->iSegid, i, pDlidx->pgno),
+          pDlidx->buf.p, pDlidx->buf.n
+      );
+      fts5WriteDlidxGrow(p, pWriter, i+2);
+      pDlidx = &pWriter->aDlidx[i];
+      if( p->rc==SQLITE_OK && pDlidx[1].buf.n==0 ){
+        i64 iFirst = fts5DlidxExtractFirstRowid(&pDlidx->buf);
+
+        /* This was the root node. Push its first rowid up to the new root. */
+        pDlidx[1].pgno = pDlidx->pgno;
+        sqlite3Fts5BufferAppendVarint(&p->rc, &pDlidx[1].buf, 0);
+        sqlite3Fts5BufferAppendVarint(&p->rc, &pDlidx[1].buf, pDlidx->pgno);
+        sqlite3Fts5BufferAppendVarint(&p->rc, &pDlidx[1].buf, iFirst);
+        pDlidx[1].bPrevValid = 1;
+        pDlidx[1].iPrev = iFirst;
+      }
+
+      sqlite3Fts5BufferZero(&pDlidx->buf);
+      pDlidx->bPrevValid = 0;
+      pDlidx->pgno++;
+    }else{
+      bDone = 1;
+    }
+
+    if( pDlidx->bPrevValid ){
+      iVal = iRowid - pDlidx->iPrev;
+    }else{
+      i64 iPgno = (i==0 ? pWriter->writer.pgno : pDlidx[-1].pgno);
+      assert( pDlidx->buf.n==0 );
+      sqlite3Fts5BufferAppendVarint(&p->rc, &pDlidx->buf, !bDone);
+      sqlite3Fts5BufferAppendVarint(&p->rc, &pDlidx->buf, iPgno);
+      iVal = iRowid;
+    }
+
+    sqlite3Fts5BufferAppendVarint(&p->rc, &pDlidx->buf, iVal);
+    pDlidx->bPrevValid = 1;
+    pDlidx->iPrev = iRowid;
+  }
+}
+
+static void fts5WriteFlushLeaf(Fts5Index *p, Fts5SegWriter *pWriter){
+  static const u8 zero[] = { 0x00, 0x00, 0x00, 0x00 };
+  Fts5PageWriter *pPage = &pWriter->writer;
+  i64 iRowid;
+
+static int nCall = 0;
+nCall++;
+
+  assert( (pPage->pgidx.n==0)==(pWriter->bFirstTermInPage) );
+
+  /* Set the szLeaf header field. */
+  assert( 0==fts5GetU16(&pPage->buf.p[2]) );
+  fts5PutU16(&pPage->buf.p[2], (u16)pPage->buf.n);
+
+  if( pWriter->bFirstTermInPage ){
+    /* No term was written to this page. */
+    assert( pPage->pgidx.n==0 );
+    fts5WriteBtreeNoTerm(p, pWriter);
+  }else{
+    /* Append the pgidx to the page buffer. Set the szLeaf header field. */
+    fts5BufferAppendBlob(&p->rc, &pPage->buf, pPage->pgidx.n, pPage->pgidx.p);
+  }
+
+  /* Write the page out to disk */
+  iRowid = FTS5_SEGMENT_ROWID(pWriter->iSegid, pPage->pgno);
+  fts5DataWrite(p, iRowid, pPage->buf.p, pPage->buf.n);
+
+  /* Initialize the next page. */
+  fts5BufferZero(&pPage->buf);
+  fts5BufferZero(&pPage->pgidx);
+  fts5BufferAppendBlob(&p->rc, &pPage->buf, 4, zero);
+  pPage->iPrevPgidx = 0;
+  pPage->pgno++;
+
+  /* Increase the leaves written counter */
+  pWriter->nLeafWritten++;
+
+  /* The new leaf holds no terms or rowids */
+  pWriter->bFirstTermInPage = 1;
+  pWriter->bFirstRowidInPage = 1;
+}
+
+/*
+** Append term pTerm/nTerm to the segment being written by the writer passed
+** as the second argument.
+**
+** If an error occurs, set the Fts5Index.rc error code. If an error has 
+** already occurred, this function is a no-op.
+*/
+static void fts5WriteAppendTerm(
+  Fts5Index *p, 
+  Fts5SegWriter *pWriter,
+  int nTerm, const u8 *pTerm 
+){
+  int nPrefix;                    /* Bytes of prefix compression for term */
+  Fts5PageWriter *pPage = &pWriter->writer;
+  Fts5Buffer *pPgidx = &pWriter->writer.pgidx;
+
+  assert( p->rc==SQLITE_OK );
+  assert( pPage->buf.n>=4 );
+  assert( pPage->buf.n>4 || pWriter->bFirstTermInPage );
+
+  /* If the current leaf page is full, flush it to disk. */
+  if( (pPage->buf.n + pPgidx->n + nTerm + 2)>=p->pConfig->pgsz ){
+    if( pPage->buf.n>4 ){
+      fts5WriteFlushLeaf(p, pWriter);
+    }
+    fts5BufferGrow(&p->rc, &pPage->buf, nTerm+FTS5_DATA_PADDING);
+  }
+  
+  /* TODO1: Updating pgidx here. */
+  pPgidx->n += sqlite3Fts5PutVarint(
+      &pPgidx->p[pPgidx->n], pPage->buf.n - pPage->iPrevPgidx
+  );
+  pPage->iPrevPgidx = pPage->buf.n;
+#if 0
+  fts5PutU16(&pPgidx->p[pPgidx->n], pPage->buf.n);
+  pPgidx->n += 2;
+#endif
+
+  if( pWriter->bFirstTermInPage ){
+    nPrefix = 0;
+    if( pPage->pgno!=1 ){
+      /* This is the first term on a leaf that is not the leftmost leaf in
+      ** the segment b-tree. In this case it is necessary to add a term to
+      ** the b-tree hierarchy that is (a) larger than the largest term 
+      ** already written to the segment and (b) smaller than or equal to
+      ** this term. In other words, a prefix of (pTerm/nTerm) that is one
+      ** byte longer than the longest prefix (pTerm/nTerm) shares with the
+      ** previous term. 
+      **
+      ** Usually, the previous term is available in pPage->term. The exception
+      ** is if this is the first term written in an incremental-merge step.
+      ** In this case the previous term is not available, so just write a
+      ** copy of (pTerm/nTerm) into the parent node. This is slightly
+      ** inefficient, but still correct.  */
+      int n = nTerm;
+      if( pPage->term.n ){
+        n = 1 + fts5PrefixCompress(pPage->term.n, pPage->term.p, pTerm);
+      }
+      fts5WriteBtreeTerm(p, pWriter, n, pTerm);
+      pPage = &pWriter->writer;
+    }
+  }else{
+    nPrefix = fts5PrefixCompress(pPage->term.n, pPage->term.p, pTerm);
+    fts5BufferAppendVarint(&p->rc, &pPage->buf, nPrefix);
+  }
+
+  /* Append the number of bytes of new data, then the term data itself
+  ** to the page. */
+  fts5BufferAppendVarint(&p->rc, &pPage->buf, nTerm - nPrefix);
+  fts5BufferAppendBlob(&p->rc, &pPage->buf, nTerm - nPrefix, &pTerm[nPrefix]);
+
+  /* Update the Fts5PageWriter.term field. */
+  fts5BufferSet(&p->rc, &pPage->term, nTerm, pTerm);
+  pWriter->bFirstTermInPage = 0;
+
+  pWriter->bFirstRowidInPage = 0;
+  pWriter->bFirstRowidInDoclist = 1;
+
+  assert( p->rc || (pWriter->nDlidx>0 && pWriter->aDlidx[0].buf.n==0) );
+  pWriter->aDlidx[0].pgno = pPage->pgno;
+}
+
+/*
+** Append a rowid and position-list size field to the writers output. 
+*/
+static void fts5WriteAppendRowid(
+  Fts5Index *p, 
+  Fts5SegWriter *pWriter,
+  i64 iRowid
+){
+  if( p->rc==SQLITE_OK ){
+    Fts5PageWriter *pPage = &pWriter->writer;
+
+    if( (pPage->buf.n + pPage->pgidx.n)>=p->pConfig->pgsz ){
+      fts5WriteFlushLeaf(p, pWriter);
+    }
+
+    /* If this is to be the first rowid written to the page, set the 
+    ** rowid-pointer in the page-header. Also append a value to the dlidx
+    ** buffer, in case a doclist-index is required.  */
+    if( pWriter->bFirstRowidInPage ){
+      fts5PutU16(pPage->buf.p, (u16)pPage->buf.n);
+      fts5WriteDlidxAppend(p, pWriter, iRowid);
+    }
+
+    /* Write the rowid. */
+    if( pWriter->bFirstRowidInDoclist || pWriter->bFirstRowidInPage ){
+      fts5BufferAppendVarint(&p->rc, &pPage->buf, iRowid);
+    }else{
+      assert( p->rc || iRowid>pWriter->iPrevRowid );
+      fts5BufferAppendVarint(&p->rc, &pPage->buf, iRowid - pWriter->iPrevRowid);
+    }
+    pWriter->iPrevRowid = iRowid;
+    pWriter->bFirstRowidInDoclist = 0;
+    pWriter->bFirstRowidInPage = 0;
+  }
+}
+
+static void fts5WriteAppendPoslistData(
+  Fts5Index *p, 
+  Fts5SegWriter *pWriter, 
+  const u8 *aData, 
+  int nData
+){
+  Fts5PageWriter *pPage = &pWriter->writer;
+  const u8 *a = aData;
+  int n = nData;
+  
+  assert( p->pConfig->pgsz>0 );
+  while( p->rc==SQLITE_OK 
+     && (pPage->buf.n + pPage->pgidx.n + n)>=p->pConfig->pgsz 
+  ){
+    int nReq = p->pConfig->pgsz - pPage->buf.n - pPage->pgidx.n;
+    int nCopy = 0;
+    while( nCopy<nReq ){
+      i64 dummy;
+      nCopy += fts5GetVarint(&a[nCopy], (u64*)&dummy);
+    }
+    fts5BufferAppendBlob(&p->rc, &pPage->buf, nCopy, a);
+    a += nCopy;
+    n -= nCopy;
+    fts5WriteFlushLeaf(p, pWriter);
+  }
+  if( n>0 ){
+    fts5BufferAppendBlob(&p->rc, &pPage->buf, n, a);
+  }
+}
+
+/*
+** Flush any data cached by the writer object to the database. Free any
+** allocations associated with the writer.
+*/
+static void fts5WriteFinish(
+  Fts5Index *p, 
+  Fts5SegWriter *pWriter,         /* Writer object */
+  int *pnLeaf                     /* OUT: Number of leaf pages in b-tree */
+){
+  int i;
+  Fts5PageWriter *pLeaf = &pWriter->writer;
+  if( p->rc==SQLITE_OK ){
+    assert( pLeaf->pgno>=1 );
+    if( pLeaf->buf.n>4 ){
+      fts5WriteFlushLeaf(p, pWriter);
+    }
+    *pnLeaf = pLeaf->pgno-1;
+    if( pLeaf->pgno>1 ){
+      fts5WriteFlushBtree(p, pWriter);
+    }
+  }
+  fts5BufferFree(&pLeaf->term);
+  fts5BufferFree(&pLeaf->buf);
+  fts5BufferFree(&pLeaf->pgidx);
+  fts5BufferFree(&pWriter->btterm);
+
+  for(i=0; i<pWriter->nDlidx; i++){
+    sqlite3Fts5BufferFree(&pWriter->aDlidx[i].buf);
+  }
+  sqlite3_free(pWriter->aDlidx);
+}
+
+static void fts5WriteInit(
+  Fts5Index *p, 
+  Fts5SegWriter *pWriter, 
+  int iSegid
+){
+  const int nBuffer = p->pConfig->pgsz + FTS5_DATA_PADDING;
+
+  memset(pWriter, 0, sizeof(Fts5SegWriter));
+  pWriter->iSegid = iSegid;
+
+  fts5WriteDlidxGrow(p, pWriter, 1);
+  pWriter->writer.pgno = 1;
+  pWriter->bFirstTermInPage = 1;
+  pWriter->iBtPage = 1;
+
+  assert( pWriter->writer.buf.n==0 );
+  assert( pWriter->writer.pgidx.n==0 );
+
+  /* Grow the two buffers to pgsz + padding bytes in size. */
+  sqlite3Fts5BufferSize(&p->rc, &pWriter->writer.pgidx, nBuffer);
+  sqlite3Fts5BufferSize(&p->rc, &pWriter->writer.buf, nBuffer);
+
+  if( p->pIdxWriter==0 ){
+    Fts5Config *pConfig = p->pConfig;
+    fts5IndexPrepareStmt(p, &p->pIdxWriter, sqlite3_mprintf(
+          "INSERT INTO '%q'.'%q_idx'(segid,term,pgno) VALUES(?,?,?)", 
+          pConfig->zDb, pConfig->zName
+    ));
+  }
+
+  if( p->rc==SQLITE_OK ){
+    /* Initialize the 4-byte leaf-page header to 0x00. */
+    memset(pWriter->writer.buf.p, 0, 4);
+    pWriter->writer.buf.n = 4;
+
+    /* Bind the current output segment id to the index-writer. This is an
+    ** optimization over binding the same value over and over as rows are
+    ** inserted into %_idx by the current writer.  */
+    sqlite3_bind_int(p->pIdxWriter, 1, pWriter->iSegid);
+  }
+}
+
+/*
+** Iterator pIter was used to iterate through the input segments of on an
+** incremental merge operation. This function is called if the incremental
+** merge step has finished but the input has not been completely exhausted.
+*/
+static void fts5TrimSegments(Fts5Index *p, Fts5Iter *pIter){
+  int i;
+  Fts5Buffer buf;
+  memset(&buf, 0, sizeof(Fts5Buffer));
+  for(i=0; i<pIter->nSeg; i++){
+    Fts5SegIter *pSeg = &pIter->aSeg[i];
+    if( pSeg->pSeg==0 ){
+      /* no-op */
+    }else if( pSeg->pLeaf==0 ){
+      /* All keys from this input segment have been transfered to the output.
+      ** Set both the first and last page-numbers to 0 to indicate that the
+      ** segment is now empty. */
+      pSeg->pSeg->pgnoLast = 0;
+      pSeg->pSeg->pgnoFirst = 0;
+    }else{
+      int iOff = pSeg->iTermLeafOffset;     /* Offset on new first leaf page */
+      i64 iLeafRowid;
+      Fts5Data *pData;
+      int iId = pSeg->pSeg->iSegid;
+      u8 aHdr[4] = {0x00, 0x00, 0x00, 0x00};
+
+      iLeafRowid = FTS5_SEGMENT_ROWID(iId, pSeg->iTermLeafPgno);
+      pData = fts5DataRead(p, iLeafRowid);
+      if( pData ){
+        fts5BufferZero(&buf);
+        fts5BufferGrow(&p->rc, &buf, pData->nn);
+        fts5BufferAppendBlob(&p->rc, &buf, sizeof(aHdr), aHdr);
+        fts5BufferAppendVarint(&p->rc, &buf, pSeg->term.n);
+        fts5BufferAppendBlob(&p->rc, &buf, pSeg->term.n, pSeg->term.p);
+        fts5BufferAppendBlob(&p->rc, &buf, pData->szLeaf-iOff, &pData->p[iOff]);
+        if( p->rc==SQLITE_OK ){
+          /* Set the szLeaf field */
+          fts5PutU16(&buf.p[2], (u16)buf.n);
+        }
+
+        /* Set up the new page-index array */
+        fts5BufferAppendVarint(&p->rc, &buf, 4);
+        if( pSeg->iLeafPgno==pSeg->iTermLeafPgno 
+         && pSeg->iEndofDoclist<pData->szLeaf 
+        ){
+          int nDiff = pData->szLeaf - pSeg->iEndofDoclist;
+          fts5BufferAppendVarint(&p->rc, &buf, buf.n - 1 - nDiff - 4);
+          fts5BufferAppendBlob(&p->rc, &buf, 
+              pData->nn - pSeg->iPgidxOff, &pData->p[pSeg->iPgidxOff]
+          );
+        }
+
+        fts5DataRelease(pData);
+        pSeg->pSeg->pgnoFirst = pSeg->iTermLeafPgno;
+        fts5DataDelete(p, FTS5_SEGMENT_ROWID(iId, 1), iLeafRowid);
+        fts5DataWrite(p, iLeafRowid, buf.p, buf.n);
+      }
+    }
+  }
+  fts5BufferFree(&buf);
+}
+
+static void fts5MergeChunkCallback(
+  Fts5Index *p, 
+  void *pCtx, 
+  const u8 *pChunk, int nChunk
+){
+  Fts5SegWriter *pWriter = (Fts5SegWriter*)pCtx;
+  fts5WriteAppendPoslistData(p, pWriter, pChunk, nChunk);
+}
+
+/*
+**
+*/
+static void fts5IndexMergeLevel(
+  Fts5Index *p,                   /* FTS5 backend object */
+  Fts5Structure **ppStruct,       /* IN/OUT: Stucture of index */
+  int iLvl,                       /* Level to read input from */
+  int *pnRem                      /* Write up to this many output leaves */
+){
+  Fts5Structure *pStruct = *ppStruct;
+  Fts5StructureLevel *pLvl = &pStruct->aLevel[iLvl];
+  Fts5StructureLevel *pLvlOut;
+  Fts5Iter *pIter = 0;       /* Iterator to read input data */
+  int nRem = pnRem ? *pnRem : 0;  /* Output leaf pages left to write */
+  int nInput;                     /* Number of input segments */
+  Fts5SegWriter writer;           /* Writer object */
+  Fts5StructureSegment *pSeg;     /* Output segment */
+  Fts5Buffer term;
+  int bOldest;                    /* True if the output segment is the oldest */
+  int eDetail = p->pConfig->eDetail;
+  const int flags = FTS5INDEX_QUERY_NOOUTPUT;
+
+  assert( iLvl<pStruct->nLevel );
+  assert( pLvl->nMerge<=pLvl->nSeg );
+
+  memset(&writer, 0, sizeof(Fts5SegWriter));
+  memset(&term, 0, sizeof(Fts5Buffer));
+  if( pLvl->nMerge ){
+    pLvlOut = &pStruct->aLevel[iLvl+1];
+    assert( pLvlOut->nSeg>0 );
+    nInput = pLvl->nMerge;
+    pSeg = &pLvlOut->aSeg[pLvlOut->nSeg-1];
+
+    fts5WriteInit(p, &writer, pSeg->iSegid);
+    writer.writer.pgno = pSeg->pgnoLast+1;
+    writer.iBtPage = 0;
+  }else{
+    int iSegid = fts5AllocateSegid(p, pStruct);
+
+    /* Extend the Fts5Structure object as required to ensure the output
+    ** segment exists. */
+    if( iLvl==pStruct->nLevel-1 ){
+      fts5StructureAddLevel(&p->rc, ppStruct);
+      pStruct = *ppStruct;
+    }
+    fts5StructureExtendLevel(&p->rc, pStruct, iLvl+1, 1, 0);
+    if( p->rc ) return;
+    pLvl = &pStruct->aLevel[iLvl];
+    pLvlOut = &pStruct->aLevel[iLvl+1];
+
+    fts5WriteInit(p, &writer, iSegid);
+
+    /* Add the new segment to the output level */
+    pSeg = &pLvlOut->aSeg[pLvlOut->nSeg];
+    pLvlOut->nSeg++;
+    pSeg->pgnoFirst = 1;
+    pSeg->iSegid = iSegid;
+    pStruct->nSegment++;
+
+    /* Read input from all segments in the input level */
+    nInput = pLvl->nSeg;
+  }
+  bOldest = (pLvlOut->nSeg==1 && pStruct->nLevel==iLvl+2);
+
+  assert( iLvl>=0 );
+  for(fts5MultiIterNew(p, pStruct, flags, 0, 0, 0, iLvl, nInput, &pIter);
+      fts5MultiIterEof(p, pIter)==0;
+      fts5MultiIterNext(p, pIter, 0, 0)
+  ){
+    Fts5SegIter *pSegIter = &pIter->aSeg[ pIter->aFirst[1].iFirst ];
+    int nPos;                     /* position-list size field value */
+    int nTerm;
+    const u8 *pTerm;
+
+    /* Check for key annihilation. */
+    if( pSegIter->nPos==0 && (bOldest || pSegIter->bDel==0) ) continue;
+
+    pTerm = fts5MultiIterTerm(pIter, &nTerm);
+    if( nTerm!=term.n || memcmp(pTerm, term.p, nTerm) ){
+      if( pnRem && writer.nLeafWritten>nRem ){
+        break;
+      }
+
+      /* This is a new term. Append a term to the output segment. */
+      fts5WriteAppendTerm(p, &writer, nTerm, pTerm);
+      fts5BufferSet(&p->rc, &term, nTerm, pTerm);
+    }
+
+    /* Append the rowid to the output */
+    /* WRITEPOSLISTSIZE */
+    fts5WriteAppendRowid(p, &writer, fts5MultiIterRowid(pIter));
+
+    if( eDetail==FTS5_DETAIL_NONE ){
+      if( pSegIter->bDel ){
+        fts5BufferAppendVarint(&p->rc, &writer.writer.buf, 0);
+        if( pSegIter->nPos>0 ){
+          fts5BufferAppendVarint(&p->rc, &writer.writer.buf, 0);
+        }
+      }
+    }else{
+      /* Append the position-list data to the output */
+      nPos = pSegIter->nPos*2 + pSegIter->bDel;
+      fts5BufferAppendVarint(&p->rc, &writer.writer.buf, nPos);
+      fts5ChunkIterate(p, pSegIter, (void*)&writer, fts5MergeChunkCallback);
+    }
+  }
+
+  /* Flush the last leaf page to disk. Set the output segment b-tree height
+  ** and last leaf page number at the same time.  */
+  fts5WriteFinish(p, &writer, &pSeg->pgnoLast);
+
+  if( fts5MultiIterEof(p, pIter) ){
+    int i;
+
+    /* Remove the redundant segments from the %_data table */
+    for(i=0; i<nInput; i++){
+      fts5DataRemoveSegment(p, pLvl->aSeg[i].iSegid);
+    }
+
+    /* Remove the redundant segments from the input level */
+    if( pLvl->nSeg!=nInput ){
+      int nMove = (pLvl->nSeg - nInput) * sizeof(Fts5StructureSegment);
+      memmove(pLvl->aSeg, &pLvl->aSeg[nInput], nMove);
+    }
+    pStruct->nSegment -= nInput;
+    pLvl->nSeg -= nInput;
+    pLvl->nMerge = 0;
+    if( pSeg->pgnoLast==0 ){
+      pLvlOut->nSeg--;
+      pStruct->nSegment--;
+    }
+  }else{
+    assert( pSeg->pgnoLast>0 );
+    fts5TrimSegments(p, pIter);
+    pLvl->nMerge = nInput;
+  }
+
+  fts5MultiIterFree(pIter);
+  fts5BufferFree(&term);
+  if( pnRem ) *pnRem -= writer.nLeafWritten;
+}
+
+/*
+** Do up to nPg pages of automerge work on the index.
+**
+** Return true if any changes were actually made, or false otherwise.
+*/
+static int fts5IndexMerge(
+  Fts5Index *p,                   /* FTS5 backend object */
+  Fts5Structure **ppStruct,       /* IN/OUT: Current structure of index */
+  int nPg,                        /* Pages of work to do */
+  int nMin                        /* Minimum number of segments to merge */
+){
+  int nRem = nPg;
+  int bRet = 0;
+  Fts5Structure *pStruct = *ppStruct;
+  while( nRem>0 && p->rc==SQLITE_OK ){
+    int iLvl;                   /* To iterate through levels */
+    int iBestLvl = 0;           /* Level offering the most input segments */
+    int nBest = 0;              /* Number of input segments on best level */
+
+    /* Set iBestLvl to the level to read input segments from. */
+    assert( pStruct->nLevel>0 );
+    for(iLvl=0; iLvl<pStruct->nLevel; iLvl++){
+      Fts5StructureLevel *pLvl = &pStruct->aLevel[iLvl];
+      if( pLvl->nMerge ){
+        if( pLvl->nMerge>nBest ){
+          iBestLvl = iLvl;
+          nBest = pLvl->nMerge;
+        }
+        break;
+      }
+      if( pLvl->nSeg>nBest ){
+        nBest = pLvl->nSeg;
+        iBestLvl = iLvl;
+      }
+    }
+
+    /* If nBest is still 0, then the index must be empty. */
+#ifdef SQLITE_DEBUG
+    for(iLvl=0; nBest==0 && iLvl<pStruct->nLevel; iLvl++){
+      assert( pStruct->aLevel[iLvl].nSeg==0 );
+    }
+#endif
+
+    if( nBest<nMin && pStruct->aLevel[iBestLvl].nMerge==0 ){
+      break;
+    }
+    bRet = 1;
+    fts5IndexMergeLevel(p, &pStruct, iBestLvl, &nRem);
+    if( p->rc==SQLITE_OK && pStruct->aLevel[iBestLvl].nMerge==0 ){
+      fts5StructurePromote(p, iBestLvl+1, pStruct);
+    }
+  }
+  *ppStruct = pStruct;
+  return bRet;
+}
+
+/*
+** A total of nLeaf leaf pages of data has just been flushed to a level-0
+** segment. This function updates the write-counter accordingly and, if
+** necessary, performs incremental merge work.
+**
+** If an error occurs, set the Fts5Index.rc error code. If an error has 
+** already occurred, this function is a no-op.
+*/
+static void fts5IndexAutomerge(
+  Fts5Index *p,                   /* FTS5 backend object */
+  Fts5Structure **ppStruct,       /* IN/OUT: Current structure of index */
+  int nLeaf                       /* Number of output leaves just written */
+){
+  if( p->rc==SQLITE_OK && p->pConfig->nAutomerge>0 ){
+    Fts5Structure *pStruct = *ppStruct;
+    u64 nWrite;                   /* Initial value of write-counter */
+    int nWork;                    /* Number of work-quanta to perform */
+    int nRem;                     /* Number of leaf pages left to write */
+
+    /* Update the write-counter. While doing so, set nWork. */
+    nWrite = pStruct->nWriteCounter;
+    nWork = (int)(((nWrite + nLeaf) / p->nWorkUnit) - (nWrite / p->nWorkUnit));
+    pStruct->nWriteCounter += nLeaf;
+    nRem = (int)(p->nWorkUnit * nWork * pStruct->nLevel);
+
+    fts5IndexMerge(p, ppStruct, nRem, p->pConfig->nAutomerge);
+  }
+}
+
+static void fts5IndexCrisismerge(
+  Fts5Index *p,                   /* FTS5 backend object */
+  Fts5Structure **ppStruct        /* IN/OUT: Current structure of index */
+){
+  const int nCrisis = p->pConfig->nCrisisMerge;
+  Fts5Structure *pStruct = *ppStruct;
+  int iLvl = 0;
+
+  assert( p->rc!=SQLITE_OK || pStruct->nLevel>0 );
+  while( p->rc==SQLITE_OK && pStruct->aLevel[iLvl].nSeg>=nCrisis ){
+    fts5IndexMergeLevel(p, &pStruct, iLvl, 0);
+    assert( p->rc!=SQLITE_OK || pStruct->nLevel>(iLvl+1) );
+    fts5StructurePromote(p, iLvl+1, pStruct);
+    iLvl++;
+  }
+  *ppStruct = pStruct;
+}
+
+static int fts5IndexReturn(Fts5Index *p){
+  int rc = p->rc;
+  p->rc = SQLITE_OK;
+  return rc;
+}
+
+typedef struct Fts5FlushCtx Fts5FlushCtx;
+struct Fts5FlushCtx {
+  Fts5Index *pIdx;
+  Fts5SegWriter writer; 
+};
+
+/*
+** Buffer aBuf[] contains a list of varints, all small enough to fit
+** in a 32-bit integer. Return the size of the largest prefix of this 
+** list nMax bytes or less in size.
+*/
+static int fts5PoslistPrefix(const u8 *aBuf, int nMax){
+  int ret;
+  u32 dummy;
+  ret = fts5GetVarint32(aBuf, dummy);
+  if( ret<nMax ){
+    while( 1 ){
+      int i = fts5GetVarint32(&aBuf[ret], dummy);
+      if( (ret + i) > nMax ) break;
+      ret += i;
+    }
+  }
+  return ret;
+}
+
+/*
+** Flush the contents of in-memory hash table iHash to a new level-0 
+** segment on disk. Also update the corresponding structure record.
+**
+** If an error occurs, set the Fts5Index.rc error code. If an error has 
+** already occurred, this function is a no-op.
+*/
+static void fts5FlushOneHash(Fts5Index *p){
+  Fts5Hash *pHash = p->pHash;
+  Fts5Structure *pStruct;
+  int iSegid;
+  int pgnoLast = 0;                 /* Last leaf page number in segment */
+
+  /* Obtain a reference to the index structure and allocate a new segment-id
+  ** for the new level-0 segment.  */
+  pStruct = fts5StructureRead(p);
+  iSegid = fts5AllocateSegid(p, pStruct);
+  fts5StructureInvalidate(p);
+
+  if( iSegid ){
+    const int pgsz = p->pConfig->pgsz;
+    int eDetail = p->pConfig->eDetail;
+    Fts5StructureSegment *pSeg;   /* New segment within pStruct */
+    Fts5Buffer *pBuf;             /* Buffer in which to assemble leaf page */
+    Fts5Buffer *pPgidx;           /* Buffer in which to assemble pgidx */
+
+    Fts5SegWriter writer;
+    fts5WriteInit(p, &writer, iSegid);
+
+    pBuf = &writer.writer.buf;
+    pPgidx = &writer.writer.pgidx;
+
+    /* fts5WriteInit() should have initialized the buffers to (most likely)
+    ** the maximum space required. */
+    assert( p->rc || pBuf->nSpace>=(pgsz + FTS5_DATA_PADDING) );
+    assert( p->rc || pPgidx->nSpace>=(pgsz + FTS5_DATA_PADDING) );
+
+    /* Begin scanning through hash table entries. This loop runs once for each
+    ** term/doclist currently stored within the hash table. */
+    if( p->rc==SQLITE_OK ){
+      p->rc = sqlite3Fts5HashScanInit(pHash, 0, 0);
+    }
+    while( p->rc==SQLITE_OK && 0==sqlite3Fts5HashScanEof(pHash) ){
+      const char *zTerm;          /* Buffer containing term */
+      const u8 *pDoclist;         /* Pointer to doclist for this term */
+      int nDoclist;               /* Size of doclist in bytes */
+
+      /* Write the term for this entry to disk. */
+      sqlite3Fts5HashScanEntry(pHash, &zTerm, &pDoclist, &nDoclist);
+      fts5WriteAppendTerm(p, &writer, (int)strlen(zTerm), (const u8*)zTerm);
+
+      assert( writer.bFirstRowidInPage==0 );
+      if( pgsz>=(pBuf->n + pPgidx->n + nDoclist + 1) ){
+        /* The entire doclist will fit on the current leaf. */
+        fts5BufferSafeAppendBlob(pBuf, pDoclist, nDoclist);
+      }else{
+        i64 iRowid = 0;
+        i64 iDelta = 0;
+        int iOff = 0;
+
+        /* The entire doclist will not fit on this leaf. The following 
+        ** loop iterates through the poslists that make up the current 
+        ** doclist.  */
+        while( p->rc==SQLITE_OK && iOff<nDoclist ){
+          iOff += fts5GetVarint(&pDoclist[iOff], (u64*)&iDelta);
+          iRowid += iDelta;
+          
+          if( writer.bFirstRowidInPage ){
+            fts5PutU16(&pBuf->p[0], (u16)pBuf->n);   /* first rowid on page */
+            pBuf->n += sqlite3Fts5PutVarint(&pBuf->p[pBuf->n], iRowid);
+            writer.bFirstRowidInPage = 0;
+            fts5WriteDlidxAppend(p, &writer, iRowid);
+          }else{
+            pBuf->n += sqlite3Fts5PutVarint(&pBuf->p[pBuf->n], iDelta);
+          }
+          assert( pBuf->n<=pBuf->nSpace );
+
+          if( eDetail==FTS5_DETAIL_NONE ){
+            if( iOff<nDoclist && pDoclist[iOff]==0 ){
+              pBuf->p[pBuf->n++] = 0;
+              iOff++;
+              if( iOff<nDoclist && pDoclist[iOff]==0 ){
+                pBuf->p[pBuf->n++] = 0;
+                iOff++;
+              }
+            }
+            if( (pBuf->n + pPgidx->n)>=pgsz ){
+              fts5WriteFlushLeaf(p, &writer);
+            }
+          }else{
+            int bDummy;
+            int nPos;
+            int nCopy = fts5GetPoslistSize(&pDoclist[iOff], &nPos, &bDummy);
+            nCopy += nPos;
+            if( (pBuf->n + pPgidx->n + nCopy) <= pgsz ){
+              /* The entire poslist will fit on the current leaf. So copy
+              ** it in one go. */
+              fts5BufferSafeAppendBlob(pBuf, &pDoclist[iOff], nCopy);
+            }else{
+              /* The entire poslist will not fit on this leaf. So it needs
+              ** to be broken into sections. The only qualification being
+              ** that each varint must be stored contiguously.  */
+              const u8 *pPoslist = &pDoclist[iOff];
+              int iPos = 0;
+              while( p->rc==SQLITE_OK ){
+                int nSpace = pgsz - pBuf->n - pPgidx->n;
+                int n = 0;
+                if( (nCopy - iPos)<=nSpace ){
+                  n = nCopy - iPos;
+                }else{
+                  n = fts5PoslistPrefix(&pPoslist[iPos], nSpace);
+                }
+                assert( n>0 );
+                fts5BufferSafeAppendBlob(pBuf, &pPoslist[iPos], n);
+                iPos += n;
+                if( (pBuf->n + pPgidx->n)>=pgsz ){
+                  fts5WriteFlushLeaf(p, &writer);
+                }
+                if( iPos>=nCopy ) break;
+              }
+            }
+            iOff += nCopy;
+          }
+        }
+      }
+
+      /* TODO2: Doclist terminator written here. */
+      /* pBuf->p[pBuf->n++] = '\0'; */
+      assert( pBuf->n<=pBuf->nSpace );
+      sqlite3Fts5HashScanNext(pHash);
+    }
+    sqlite3Fts5HashClear(pHash);
+    fts5WriteFinish(p, &writer, &pgnoLast);
+
+    /* Update the Fts5Structure. It is written back to the database by the
+    ** fts5StructureRelease() call below.  */
+    if( pStruct->nLevel==0 ){
+      fts5StructureAddLevel(&p->rc, &pStruct);
+    }
+    fts5StructureExtendLevel(&p->rc, pStruct, 0, 1, 0);
+    if( p->rc==SQLITE_OK ){
+      pSeg = &pStruct->aLevel[0].aSeg[ pStruct->aLevel[0].nSeg++ ];
+      pSeg->iSegid = iSegid;
+      pSeg->pgnoFirst = 1;
+      pSeg->pgnoLast = pgnoLast;
+      pStruct->nSegment++;
+    }
+    fts5StructurePromote(p, 0, pStruct);
+  }
+
+  fts5IndexAutomerge(p, &pStruct, pgnoLast);
+  fts5IndexCrisismerge(p, &pStruct);
+  fts5StructureWrite(p, pStruct);
+  fts5StructureRelease(pStruct);
+}
+
+/*
+** Flush any data stored in the in-memory hash tables to the database.
+*/
+static void fts5IndexFlush(Fts5Index *p){
+  /* Unless it is empty, flush the hash table to disk */
+  if( p->nPendingData ){
+    assert( p->pHash );
+    p->nPendingData = 0;
+    fts5FlushOneHash(p);
+  }
+}
+
+static Fts5Structure *fts5IndexOptimizeStruct(
+  Fts5Index *p, 
+  Fts5Structure *pStruct
+){
+  Fts5Structure *pNew = 0;
+  int nByte = sizeof(Fts5Structure);
+  int nSeg = pStruct->nSegment;
+  int i;
+
+  /* Figure out if this structure requires optimization. A structure does
+  ** not require optimization if either:
+  **
+  **  + it consists of fewer than two segments, or 
+  **  + all segments are on the same level, or
+  **  + all segments except one are currently inputs to a merge operation.
+  **
+  ** In the first case, return NULL. In the second, increment the ref-count
+  ** on *pStruct and return a copy of the pointer to it.
+  */
+  if( nSeg<2 ) return 0;
+  for(i=0; i<pStruct->nLevel; i++){
+    int nThis = pStruct->aLevel[i].nSeg;
+    if( nThis==nSeg || (nThis==nSeg-1 && pStruct->aLevel[i].nMerge==nThis) ){
+      fts5StructureRef(pStruct);
+      return pStruct;
+    }
+    assert( pStruct->aLevel[i].nMerge<=nThis );
+  }
+
+  nByte += (pStruct->nLevel+1) * sizeof(Fts5StructureLevel);
+  pNew = (Fts5Structure*)sqlite3Fts5MallocZero(&p->rc, nByte);
+
+  if( pNew ){
+    Fts5StructureLevel *pLvl;
+    nByte = nSeg * sizeof(Fts5StructureSegment);
+    pNew->nLevel = pStruct->nLevel+1;
+    pNew->nRef = 1;
+    pNew->nWriteCounter = pStruct->nWriteCounter;
+    pLvl = &pNew->aLevel[pStruct->nLevel];
+    pLvl->aSeg = (Fts5StructureSegment*)sqlite3Fts5MallocZero(&p->rc, nByte);
+    if( pLvl->aSeg ){
+      int iLvl, iSeg;
+      int iSegOut = 0;
+      /* Iterate through all segments, from oldest to newest. Add them to
+      ** the new Fts5Level object so that pLvl->aSeg[0] is the oldest
+      ** segment in the data structure.  */
+      for(iLvl=pStruct->nLevel-1; iLvl>=0; iLvl--){
+        for(iSeg=0; iSeg<pStruct->aLevel[iLvl].nSeg; iSeg++){
+          pLvl->aSeg[iSegOut] = pStruct->aLevel[iLvl].aSeg[iSeg];
+          iSegOut++;
+        }
+      }
+      pNew->nSegment = pLvl->nSeg = nSeg;
+    }else{
+      sqlite3_free(pNew);
+      pNew = 0;
+    }
+  }
+
+  return pNew;
+}
+
+static int sqlite3Fts5IndexOptimize(Fts5Index *p){
+  Fts5Structure *pStruct;
+  Fts5Structure *pNew = 0;
+
+  assert( p->rc==SQLITE_OK );
+  fts5IndexFlush(p);
+  pStruct = fts5StructureRead(p);
+  fts5StructureInvalidate(p);
+
+  if( pStruct ){
+    pNew = fts5IndexOptimizeStruct(p, pStruct);
+  }
+  fts5StructureRelease(pStruct);
+
+  assert( pNew==0 || pNew->nSegment>0 );
+  if( pNew ){
+    int iLvl;
+    for(iLvl=0; pNew->aLevel[iLvl].nSeg==0; iLvl++){}
+    while( p->rc==SQLITE_OK && pNew->aLevel[iLvl].nSeg>0 ){
+      int nRem = FTS5_OPT_WORK_UNIT;
+      fts5IndexMergeLevel(p, &pNew, iLvl, &nRem);
+    }
+
+    fts5StructureWrite(p, pNew);
+    fts5StructureRelease(pNew);
+  }
+
+  return fts5IndexReturn(p); 
+}
+
+/*
+** This is called to implement the special "VALUES('merge', $nMerge)"
+** INSERT command.
+*/
+static int sqlite3Fts5IndexMerge(Fts5Index *p, int nMerge){
+  Fts5Structure *pStruct = fts5StructureRead(p);
+  if( pStruct ){
+    int nMin = p->pConfig->nUsermerge;
+    fts5StructureInvalidate(p);
+    if( nMerge<0 ){
+      Fts5Structure *pNew = fts5IndexOptimizeStruct(p, pStruct);
+      fts5StructureRelease(pStruct);
+      pStruct = pNew;
+      nMin = 2;
+      nMerge = nMerge*-1;
+    }
+    if( pStruct && pStruct->nLevel ){
+      if( fts5IndexMerge(p, &pStruct, nMerge, nMin) ){
+        fts5StructureWrite(p, pStruct);
+      }
+    }
+    fts5StructureRelease(pStruct);
+  }
+  return fts5IndexReturn(p);
+}
+
+static void fts5AppendRowid(
+  Fts5Index *p,
+  i64 iDelta,
+  Fts5Iter *pUnused,
+  Fts5Buffer *pBuf
+){
+  UNUSED_PARAM(pUnused);
+  fts5BufferAppendVarint(&p->rc, pBuf, iDelta);
+}
+
+static void fts5AppendPoslist(
+  Fts5Index *p,
+  i64 iDelta,
+  Fts5Iter *pMulti,
+  Fts5Buffer *pBuf
+){
+  int nData = pMulti->base.nData;
+  assert( nData>0 );
+  if( p->rc==SQLITE_OK && 0==fts5BufferGrow(&p->rc, pBuf, nData+9+9) ){
+    fts5BufferSafeAppendVarint(pBuf, iDelta);
+    fts5BufferSafeAppendVarint(pBuf, nData*2);
+    fts5BufferSafeAppendBlob(pBuf, pMulti->base.pData, nData);
+  }
+}
+
+
+static void fts5DoclistIterNext(Fts5DoclistIter *pIter){
+  u8 *p = pIter->aPoslist + pIter->nSize + pIter->nPoslist;
+
+  assert( pIter->aPoslist );
+  if( p>=pIter->aEof ){
+    pIter->aPoslist = 0;
+  }else{
+    i64 iDelta;
+
+    p += fts5GetVarint(p, (u64*)&iDelta);
+    pIter->iRowid += iDelta;
+
+    /* Read position list size */
+    if( p[0] & 0x80 ){
+      int nPos;
+      pIter->nSize = fts5GetVarint32(p, nPos);
+      pIter->nPoslist = (nPos>>1);
+    }else{
+      pIter->nPoslist = ((int)(p[0])) >> 1;
+      pIter->nSize = 1;
+    }
+
+    pIter->aPoslist = p;
+  }
+}
+
+static void fts5DoclistIterInit(
+  Fts5Buffer *pBuf, 
+  Fts5DoclistIter *pIter
+){
+  memset(pIter, 0, sizeof(*pIter));
+  pIter->aPoslist = pBuf->p;
+  pIter->aEof = &pBuf->p[pBuf->n];
+  fts5DoclistIterNext(pIter);
+}
+
+#if 0
+/*
+** Append a doclist to buffer pBuf.
+**
+** This function assumes that space within the buffer has already been
+** allocated.
+*/
+static void fts5MergeAppendDocid(
+  Fts5Buffer *pBuf,               /* Buffer to write to */
+  i64 *piLastRowid,               /* IN/OUT: Previous rowid written (if any) */
+  i64 iRowid                      /* Rowid to append */
+){
+  assert( pBuf->n!=0 || (*piLastRowid)==0 );
+  fts5BufferSafeAppendVarint(pBuf, iRowid - *piLastRowid);
+  *piLastRowid = iRowid;
+}
+#endif
+
+#define fts5MergeAppendDocid(pBuf, iLastRowid, iRowid) {       \
+  assert( (pBuf)->n!=0 || (iLastRowid)==0 );                   \
+  fts5BufferSafeAppendVarint((pBuf), (iRowid) - (iLastRowid)); \
+  (iLastRowid) = (iRowid);                                     \
+}
+
+/*
+** Swap the contents of buffer *p1 with that of *p2.
+*/
+static void fts5BufferSwap(Fts5Buffer *p1, Fts5Buffer *p2){
+  Fts5Buffer tmp = *p1;
+  *p1 = *p2;
+  *p2 = tmp;
+}
+
+static void fts5NextRowid(Fts5Buffer *pBuf, int *piOff, i64 *piRowid){
+  int i = *piOff;
+  if( i>=pBuf->n ){
+    *piOff = -1;
+  }else{
+    u64 iVal;
+    *piOff = i + sqlite3Fts5GetVarint(&pBuf->p[i], &iVal);
+    *piRowid += iVal;
+  }
+}
+
+/*
+** This is the equivalent of fts5MergePrefixLists() for detail=none mode.
+** In this case the buffers consist of a delta-encoded list of rowids only.
+*/
+static void fts5MergeRowidLists(
+  Fts5Index *p,                   /* FTS5 backend object */
+  Fts5Buffer *p1,                 /* First list to merge */
+  Fts5Buffer *p2                  /* Second list to merge */
+){
+  int i1 = 0;
+  int i2 = 0;
+  i64 iRowid1 = 0;
+  i64 iRowid2 = 0;
+  i64 iOut = 0;
+
+  Fts5Buffer out;
+  memset(&out, 0, sizeof(out));
+  sqlite3Fts5BufferSize(&p->rc, &out, p1->n + p2->n);
+  if( p->rc ) return;
+
+  fts5NextRowid(p1, &i1, &iRowid1);
+  fts5NextRowid(p2, &i2, &iRowid2);
+  while( i1>=0 || i2>=0 ){
+    if( i1>=0 && (i2<0 || iRowid1<iRowid2) ){
+      assert( iOut==0 || iRowid1>iOut );
+      fts5BufferSafeAppendVarint(&out, iRowid1 - iOut);
+      iOut = iRowid1;
+      fts5NextRowid(p1, &i1, &iRowid1);
+    }else{
+      assert( iOut==0 || iRowid2>iOut );
+      fts5BufferSafeAppendVarint(&out, iRowid2 - iOut);
+      iOut = iRowid2;
+      if( i1>=0 && iRowid1==iRowid2 ){
+        fts5NextRowid(p1, &i1, &iRowid1);
+      }
+      fts5NextRowid(p2, &i2, &iRowid2);
+    }
+  }
+
+  fts5BufferSwap(&out, p1);
+  fts5BufferFree(&out);
+}
+
+/*
+** Buffers p1 and p2 contain doclists. This function merges the content
+** of the two doclists together and sets buffer p1 to the result before
+** returning.
+**
+** If an error occurs, an error code is left in p->rc. If an error has
+** already occurred, this function is a no-op.
+*/
+static void fts5MergePrefixLists(
+  Fts5Index *p,                   /* FTS5 backend object */
+  Fts5Buffer *p1,                 /* First list to merge */
+  Fts5Buffer *p2                  /* Second list to merge */
+){
+  if( p2->n ){
+    i64 iLastRowid = 0;
+    Fts5DoclistIter i1;
+    Fts5DoclistIter i2;
+    Fts5Buffer out = {0, 0, 0};
+    Fts5Buffer tmp = {0, 0, 0};
+
+    if( sqlite3Fts5BufferSize(&p->rc, &out, p1->n + p2->n) ) return;
+    fts5DoclistIterInit(p1, &i1);
+    fts5DoclistIterInit(p2, &i2);
+
+    while( 1 ){
+      if( i1.iRowid<i2.iRowid ){
+        /* Copy entry from i1 */
+        fts5MergeAppendDocid(&out, iLastRowid, i1.iRowid);
+        fts5BufferSafeAppendBlob(&out, i1.aPoslist, i1.nPoslist+i1.nSize);
+        fts5DoclistIterNext(&i1);
+        if( i1.aPoslist==0 ) break;
+      }
+      else if( i2.iRowid!=i1.iRowid ){
+        /* Copy entry from i2 */
+        fts5MergeAppendDocid(&out, iLastRowid, i2.iRowid);
+        fts5BufferSafeAppendBlob(&out, i2.aPoslist, i2.nPoslist+i2.nSize);
+        fts5DoclistIterNext(&i2);
+        if( i2.aPoslist==0 ) break;
+      }
+      else{
+        /* Merge the two position lists. */ 
+        i64 iPos1 = 0;
+        i64 iPos2 = 0;
+        int iOff1 = 0;
+        int iOff2 = 0;
+        u8 *a1 = &i1.aPoslist[i1.nSize];
+        u8 *a2 = &i2.aPoslist[i2.nSize];
+
+        i64 iPrev = 0;
+        Fts5PoslistWriter writer;
+        memset(&writer, 0, sizeof(writer));
+
+        fts5MergeAppendDocid(&out, iLastRowid, i2.iRowid);
+        fts5BufferZero(&tmp);
+        sqlite3Fts5BufferSize(&p->rc, &tmp, i1.nPoslist + i2.nPoslist);
+        if( p->rc ) break;
+
+        sqlite3Fts5PoslistNext64(a1, i1.nPoslist, &iOff1, &iPos1);
+        sqlite3Fts5PoslistNext64(a2, i2.nPoslist, &iOff2, &iPos2);
+        assert( iPos1>=0 && iPos2>=0 );
+
+        if( iPos1<iPos2 ){
+          sqlite3Fts5PoslistSafeAppend(&tmp, &iPrev, iPos1);
+          sqlite3Fts5PoslistNext64(a1, i1.nPoslist, &iOff1, &iPos1);
+        }else{
+          sqlite3Fts5PoslistSafeAppend(&tmp, &iPrev, iPos2);
+          sqlite3Fts5PoslistNext64(a2, i2.nPoslist, &iOff2, &iPos2);
+        }
+
+        if( iPos1>=0 && iPos2>=0 ){
+          while( 1 ){
+            if( iPos1<iPos2 ){
+              if( iPos1!=iPrev ){
+                sqlite3Fts5PoslistSafeAppend(&tmp, &iPrev, iPos1);
+              }
+              sqlite3Fts5PoslistNext64(a1, i1.nPoslist, &iOff1, &iPos1);
+              if( iPos1<0 ) break;
+            }else{
+              assert( iPos2!=iPrev );
+              sqlite3Fts5PoslistSafeAppend(&tmp, &iPrev, iPos2);
+              sqlite3Fts5PoslistNext64(a2, i2.nPoslist, &iOff2, &iPos2);
+              if( iPos2<0 ) break;
+            }
+          }
+        }
+
+        if( iPos1>=0 ){
+          if( iPos1!=iPrev ){
+            sqlite3Fts5PoslistSafeAppend(&tmp, &iPrev, iPos1);
+          }
+          fts5BufferSafeAppendBlob(&tmp, &a1[iOff1], i1.nPoslist-iOff1);
+        }else{
+          assert( iPos2>=0 && iPos2!=iPrev );
+          sqlite3Fts5PoslistSafeAppend(&tmp, &iPrev, iPos2);
+          fts5BufferSafeAppendBlob(&tmp, &a2[iOff2], i2.nPoslist-iOff2);
+        }
+
+        /* WRITEPOSLISTSIZE */
+        fts5BufferSafeAppendVarint(&out, tmp.n * 2);
+        fts5BufferSafeAppendBlob(&out, tmp.p, tmp.n);
+        fts5DoclistIterNext(&i1);
+        fts5DoclistIterNext(&i2);
+        if( i1.aPoslist==0 || i2.aPoslist==0 ) break;
+      }
+    }
+
+    if( i1.aPoslist ){
+      fts5MergeAppendDocid(&out, iLastRowid, i1.iRowid);
+      fts5BufferSafeAppendBlob(&out, i1.aPoslist, i1.aEof - i1.aPoslist);
+    }
+    else if( i2.aPoslist ){
+      fts5MergeAppendDocid(&out, iLastRowid, i2.iRowid);
+      fts5BufferSafeAppendBlob(&out, i2.aPoslist, i2.aEof - i2.aPoslist);
+    }
+
+    fts5BufferSet(&p->rc, p1, out.n, out.p);
+    fts5BufferFree(&tmp);
+    fts5BufferFree(&out);
+  }
+}
+
+static void fts5SetupPrefixIter(
+  Fts5Index *p,                   /* Index to read from */
+  int bDesc,                      /* True for "ORDER BY rowid DESC" */
+  const u8 *pToken,               /* Buffer containing prefix to match */
+  int nToken,                     /* Size of buffer pToken in bytes */
+  Fts5Colset *pColset,            /* Restrict matches to these columns */
+  Fts5Iter **ppIter          /* OUT: New iterator */
+){
+  Fts5Structure *pStruct;
+  Fts5Buffer *aBuf;
+  const int nBuf = 32;
+
+  void (*xMerge)(Fts5Index*, Fts5Buffer*, Fts5Buffer*);
+  void (*xAppend)(Fts5Index*, i64, Fts5Iter*, Fts5Buffer*);
+  if( p->pConfig->eDetail==FTS5_DETAIL_NONE ){
+    xMerge = fts5MergeRowidLists;
+    xAppend = fts5AppendRowid;
+  }else{
+    xMerge = fts5MergePrefixLists;
+    xAppend = fts5AppendPoslist;
+  }
+
+  aBuf = (Fts5Buffer*)fts5IdxMalloc(p, sizeof(Fts5Buffer)*nBuf);
+  pStruct = fts5StructureRead(p);
+
+  if( aBuf && pStruct ){
+    const int flags = FTS5INDEX_QUERY_SCAN 
+                    | FTS5INDEX_QUERY_SKIPEMPTY 
+                    | FTS5INDEX_QUERY_NOOUTPUT;
+    int i;
+    i64 iLastRowid = 0;
+    Fts5Iter *p1 = 0;     /* Iterator used to gather data from index */
+    Fts5Data *pData;
+    Fts5Buffer doclist;
+    int bNewTerm = 1;
+
+    memset(&doclist, 0, sizeof(doclist));
+    fts5MultiIterNew(p, pStruct, flags, pColset, pToken, nToken, -1, 0, &p1);
+    fts5IterSetOutputCb(&p->rc, p1);
+    for( /* no-op */ ;
+        fts5MultiIterEof(p, p1)==0;
+        fts5MultiIterNext2(p, p1, &bNewTerm)
+    ){
+      Fts5SegIter *pSeg = &p1->aSeg[ p1->aFirst[1].iFirst ];
+      int nTerm = pSeg->term.n;
+      const u8 *pTerm = pSeg->term.p;
+      p1->xSetOutputs(p1, pSeg);
+
+      assert_nc( memcmp(pToken, pTerm, MIN(nToken, nTerm))<=0 );
+      if( bNewTerm ){
+        if( nTerm<nToken || memcmp(pToken, pTerm, nToken) ) break;
+      }
+
+      if( p1->base.nData==0 ) continue;
+
+      if( p1->base.iRowid<=iLastRowid && doclist.n>0 ){
+        for(i=0; p->rc==SQLITE_OK && doclist.n; i++){
+          assert( i<nBuf );
+          if( aBuf[i].n==0 ){
+            fts5BufferSwap(&doclist, &aBuf[i]);
+            fts5BufferZero(&doclist);
+          }else{
+            xMerge(p, &doclist, &aBuf[i]);
+            fts5BufferZero(&aBuf[i]);
+          }
+        }
+        iLastRowid = 0;
+      }
+
+      xAppend(p, p1->base.iRowid-iLastRowid, p1, &doclist);
+      iLastRowid = p1->base.iRowid;
+    }
+
+    for(i=0; i<nBuf; i++){
+      if( p->rc==SQLITE_OK ){
+        xMerge(p, &doclist, &aBuf[i]);
+      }
+      fts5BufferFree(&aBuf[i]);
+    }
+    fts5MultiIterFree(p1);
+
+    pData = fts5IdxMalloc(p, sizeof(Fts5Data) + doclist.n);
+    if( pData ){
+      pData->p = (u8*)&pData[1];
+      pData->nn = pData->szLeaf = doclist.n;
+      memcpy(pData->p, doclist.p, doclist.n);
+      fts5MultiIterNew2(p, pData, bDesc, ppIter);
+    }
+    fts5BufferFree(&doclist);
+  }
+
+  fts5StructureRelease(pStruct);
+  sqlite3_free(aBuf);
+}
+
+
+/*
+** Indicate that all subsequent calls to sqlite3Fts5IndexWrite() pertain
+** to the document with rowid iRowid.
+*/
+static int sqlite3Fts5IndexBeginWrite(Fts5Index *p, int bDelete, i64 iRowid){
+  assert( p->rc==SQLITE_OK );
+
+  /* Allocate the hash table if it has not already been allocated */
+  if( p->pHash==0 ){
+    p->rc = sqlite3Fts5HashNew(p->pConfig, &p->pHash, &p->nPendingData);
+  }
+
+  /* Flush the hash table to disk if required */
+  if( iRowid<p->iWriteRowid 
+   || (iRowid==p->iWriteRowid && p->bDelete==0)
+   || (p->nPendingData > p->pConfig->nHashSize) 
+  ){
+    fts5IndexFlush(p);
+  }
+
+  p->iWriteRowid = iRowid;
+  p->bDelete = bDelete;
+  return fts5IndexReturn(p);
+}
+
+/*
+** Commit data to disk.
+*/
+static int sqlite3Fts5IndexSync(Fts5Index *p, int bCommit){
+  assert( p->rc==SQLITE_OK );
+  fts5IndexFlush(p);
+  if( bCommit ) fts5CloseReader(p);
+  return fts5IndexReturn(p);
+}
+
+/*
+** Discard any data stored in the in-memory hash tables. Do not write it
+** to the database. Additionally, assume that the contents of the %_data
+** table may have changed on disk. So any in-memory caches of %_data 
+** records must be invalidated.
+*/
+static int sqlite3Fts5IndexRollback(Fts5Index *p){
+  fts5CloseReader(p);
+  fts5IndexDiscardData(p);
+  fts5StructureInvalidate(p);
+  /* assert( p->rc==SQLITE_OK ); */
+  return SQLITE_OK;
+}
+
+/*
+** The %_data table is completely empty when this function is called. This
+** function populates it with the initial structure objects for each index,
+** and the initial version of the "averages" record (a zero-byte blob).
+*/
+static int sqlite3Fts5IndexReinit(Fts5Index *p){
+  Fts5Structure s;
+  fts5StructureInvalidate(p);
+  memset(&s, 0, sizeof(Fts5Structure));
+  fts5DataWrite(p, FTS5_AVERAGES_ROWID, (const u8*)"", 0);
+  fts5StructureWrite(p, &s);
+  return fts5IndexReturn(p);
+}
+
+/*
+** Open a new Fts5Index handle. If the bCreate argument is true, create
+** and initialize the underlying %_data table.
+**
+** If successful, set *pp to point to the new object and return SQLITE_OK.
+** Otherwise, set *pp to NULL and return an SQLite error code.
+*/
+static int sqlite3Fts5IndexOpen(
+  Fts5Config *pConfig, 
+  int bCreate, 
+  Fts5Index **pp,
+  char **pzErr
+){
+  int rc = SQLITE_OK;
+  Fts5Index *p;                   /* New object */
+
+  *pp = p = (Fts5Index*)sqlite3Fts5MallocZero(&rc, sizeof(Fts5Index));
+  if( rc==SQLITE_OK ){
+    p->pConfig = pConfig;
+    p->nWorkUnit = FTS5_WORK_UNIT;
+    p->zDataTbl = sqlite3Fts5Mprintf(&rc, "%s_data", pConfig->zName);
+    if( p->zDataTbl && bCreate ){
+      rc = sqlite3Fts5CreateTable(
+          pConfig, "data", "id INTEGER PRIMARY KEY, block BLOB", 0, pzErr
+      );
+      if( rc==SQLITE_OK ){
+        rc = sqlite3Fts5CreateTable(pConfig, "idx", 
+            "segid, term, pgno, PRIMARY KEY(segid, term)", 
+            1, pzErr
+        );
+      }
+      if( rc==SQLITE_OK ){
+        rc = sqlite3Fts5IndexReinit(p);
+      }
+    }
+  }
+
+  assert( rc!=SQLITE_OK || p->rc==SQLITE_OK );
+  if( rc ){
+    sqlite3Fts5IndexClose(p);
+    *pp = 0;
+  }
+  return rc;
+}
+
+/*
+** Close a handle opened by an earlier call to sqlite3Fts5IndexOpen().
+*/
+static int sqlite3Fts5IndexClose(Fts5Index *p){
+  int rc = SQLITE_OK;
+  if( p ){
+    assert( p->pReader==0 );
+    fts5StructureInvalidate(p);
+    sqlite3_finalize(p->pWriter);
+    sqlite3_finalize(p->pDeleter);
+    sqlite3_finalize(p->pIdxWriter);
+    sqlite3_finalize(p->pIdxDeleter);
+    sqlite3_finalize(p->pIdxSelect);
+    sqlite3_finalize(p->pDataVersion);
+    sqlite3Fts5HashFree(p->pHash);
+    sqlite3_free(p->zDataTbl);
+    sqlite3_free(p);
+  }
+  return rc;
+}
+
+/*
+** Argument p points to a buffer containing utf-8 text that is n bytes in 
+** size. Return the number of bytes in the nChar character prefix of the
+** buffer, or 0 if there are less than nChar characters in total.
+*/
+static int sqlite3Fts5IndexCharlenToBytelen(
+  const char *p, 
+  int nByte, 
+  int nChar
+){
+  int n = 0;
+  int i;
+  for(i=0; i<nChar; i++){
+    if( n>=nByte ) return 0;      /* Input contains fewer than nChar chars */
+    if( (unsigned char)p[n++]>=0xc0 ){
+      while( (p[n] & 0xc0)==0x80 ) n++;
+    }
+  }
+  return n;
+}
+
+/*
+** pIn is a UTF-8 encoded string, nIn bytes in size. Return the number of
+** unicode characters in the string.
+*/
+static int fts5IndexCharlen(const char *pIn, int nIn){
+  int nChar = 0;            
+  int i = 0;
+  while( i<nIn ){
+    if( (unsigned char)pIn[i++]>=0xc0 ){
+      while( i<nIn && (pIn[i] & 0xc0)==0x80 ) i++;
+    }
+    nChar++;
+  }
+  return nChar;
+}
+
+/*
+** Insert or remove data to or from the index. Each time a document is 
+** added to or removed from the index, this function is called one or more
+** times.
+**
+** For an insert, it must be called once for each token in the new document.
+** If the operation is a delete, it must be called (at least) once for each
+** unique token in the document with an iCol value less than zero. The iPos
+** argument is ignored for a delete.
+*/
+static int sqlite3Fts5IndexWrite(
+  Fts5Index *p,                   /* Index to write to */
+  int iCol,                       /* Column token appears in (-ve -> delete) */
+  int iPos,                       /* Position of token within column */
+  const char *pToken, int nToken  /* Token to add or remove to or from index */
+){
+  int i;                          /* Used to iterate through indexes */
+  int rc = SQLITE_OK;             /* Return code */
+  Fts5Config *pConfig = p->pConfig;
+
+  assert( p->rc==SQLITE_OK );
+  assert( (iCol<0)==p->bDelete );
+
+  /* Add the entry to the main terms index. */
+  rc = sqlite3Fts5HashWrite(
+      p->pHash, p->iWriteRowid, iCol, iPos, FTS5_MAIN_PREFIX, pToken, nToken
+  );
+
+  for(i=0; i<pConfig->nPrefix && rc==SQLITE_OK; i++){
+    const int nChar = pConfig->aPrefix[i];
+    int nByte = sqlite3Fts5IndexCharlenToBytelen(pToken, nToken, nChar);
+    if( nByte ){
+      rc = sqlite3Fts5HashWrite(p->pHash, 
+          p->iWriteRowid, iCol, iPos, (char)(FTS5_MAIN_PREFIX+i+1), pToken,
+          nByte
+      );
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Open a new iterator to iterate though all rowid that match the 
+** specified token or token prefix.
+*/
+static int sqlite3Fts5IndexQuery(
+  Fts5Index *p,                   /* FTS index to query */
+  const char *pToken, int nToken, /* Token (or prefix) to query for */
+  int flags,                      /* Mask of FTS5INDEX_QUERY_X flags */
+  Fts5Colset *pColset,            /* Match these columns only */
+  Fts5IndexIter **ppIter          /* OUT: New iterator object */
+){
+  Fts5Config *pConfig = p->pConfig;
+  Fts5Iter *pRet = 0;
+  Fts5Buffer buf = {0, 0, 0};
+
+  /* If the QUERY_SCAN flag is set, all other flags must be clear. */
+  assert( (flags & FTS5INDEX_QUERY_SCAN)==0 || flags==FTS5INDEX_QUERY_SCAN );
+
+  if( sqlite3Fts5BufferSize(&p->rc, &buf, nToken+1)==0 ){
+    int iIdx = 0;                 /* Index to search */
+    memcpy(&buf.p[1], pToken, nToken);
+
+    /* Figure out which index to search and set iIdx accordingly. If this
+    ** is a prefix query for which there is no prefix index, set iIdx to
+    ** greater than pConfig->nPrefix to indicate that the query will be
+    ** satisfied by scanning multiple terms in the main index.
+    **
+    ** If the QUERY_TEST_NOIDX flag was specified, then this must be a
+    ** prefix-query. Instead of using a prefix-index (if one exists), 
+    ** evaluate the prefix query using the main FTS index. This is used
+    ** for internal sanity checking by the integrity-check in debug 
+    ** mode only.  */
+#ifdef SQLITE_DEBUG
+    if( pConfig->bPrefixIndex==0 || (flags & FTS5INDEX_QUERY_TEST_NOIDX) ){
+      assert( flags & FTS5INDEX_QUERY_PREFIX );
+      iIdx = 1+pConfig->nPrefix;
+    }else
+#endif
+    if( flags & FTS5INDEX_QUERY_PREFIX ){
+      int nChar = fts5IndexCharlen(pToken, nToken);
+      for(iIdx=1; iIdx<=pConfig->nPrefix; iIdx++){
+        if( pConfig->aPrefix[iIdx-1]==nChar ) break;
+      }
+    }
+
+    if( iIdx<=pConfig->nPrefix ){
+      /* Straight index lookup */
+      Fts5Structure *pStruct = fts5StructureRead(p);
+      buf.p[0] = (u8)(FTS5_MAIN_PREFIX + iIdx);
+      if( pStruct ){
+        fts5MultiIterNew(p, pStruct, flags | FTS5INDEX_QUERY_SKIPEMPTY, 
+            pColset, buf.p, nToken+1, -1, 0, &pRet
+        );
+        fts5StructureRelease(pStruct);
+      }
+    }else{
+      /* Scan multiple terms in the main index */
+      int bDesc = (flags & FTS5INDEX_QUERY_DESC)!=0;
+      buf.p[0] = FTS5_MAIN_PREFIX;
+      fts5SetupPrefixIter(p, bDesc, buf.p, nToken+1, pColset, &pRet);
+      assert( p->rc!=SQLITE_OK || pRet->pColset==0 );
+      fts5IterSetOutputCb(&p->rc, pRet);
+      if( p->rc==SQLITE_OK ){
+        Fts5SegIter *pSeg = &pRet->aSeg[pRet->aFirst[1].iFirst];
+        if( pSeg->pLeaf ) pRet->xSetOutputs(pRet, pSeg);
+      }
+    }
+
+    if( p->rc ){
+      sqlite3Fts5IterClose(&pRet->base);
+      pRet = 0;
+      fts5CloseReader(p);
+    }
+
+    *ppIter = &pRet->base;
+    sqlite3Fts5BufferFree(&buf);
+  }
+  return fts5IndexReturn(p);
+}
+
+/*
+** Return true if the iterator passed as the only argument is at EOF.
+*/
+/*
+** Move to the next matching rowid. 
+*/
+static int sqlite3Fts5IterNext(Fts5IndexIter *pIndexIter){
+  Fts5Iter *pIter = (Fts5Iter*)pIndexIter;
+  assert( pIter->pIndex->rc==SQLITE_OK );
+  fts5MultiIterNext(pIter->pIndex, pIter, 0, 0);
+  return fts5IndexReturn(pIter->pIndex);
+}
+
+/*
+** Move to the next matching term/rowid. Used by the fts5vocab module.
+*/
+static int sqlite3Fts5IterNextScan(Fts5IndexIter *pIndexIter){
+  Fts5Iter *pIter = (Fts5Iter*)pIndexIter;
+  Fts5Index *p = pIter->pIndex;
+
+  assert( pIter->pIndex->rc==SQLITE_OK );
+
+  fts5MultiIterNext(p, pIter, 0, 0);
+  if( p->rc==SQLITE_OK ){
+    Fts5SegIter *pSeg = &pIter->aSeg[ pIter->aFirst[1].iFirst ];
+    if( pSeg->pLeaf && pSeg->term.p[0]!=FTS5_MAIN_PREFIX ){
+      fts5DataRelease(pSeg->pLeaf);
+      pSeg->pLeaf = 0;
+      pIter->base.bEof = 1;
+    }
+  }
+
+  return fts5IndexReturn(pIter->pIndex);
+}
+
+/*
+** Move to the next matching rowid that occurs at or after iMatch. The
+** definition of "at or after" depends on whether this iterator iterates
+** in ascending or descending rowid order.
+*/
+static int sqlite3Fts5IterNextFrom(Fts5IndexIter *pIndexIter, i64 iMatch){
+  Fts5Iter *pIter = (Fts5Iter*)pIndexIter;
+  fts5MultiIterNextFrom(pIter->pIndex, pIter, iMatch);
+  return fts5IndexReturn(pIter->pIndex);
+}
+
+/*
+** Return the current term.
+*/
+static const char *sqlite3Fts5IterTerm(Fts5IndexIter *pIndexIter, int *pn){
+  int n;
+  const char *z = (const char*)fts5MultiIterTerm((Fts5Iter*)pIndexIter, &n);
+  *pn = n-1;
+  return &z[1];
+}
+
+/*
+** Close an iterator opened by an earlier call to sqlite3Fts5IndexQuery().
+*/
+static void sqlite3Fts5IterClose(Fts5IndexIter *pIndexIter){
+  if( pIndexIter ){
+    Fts5Iter *pIter = (Fts5Iter*)pIndexIter;
+    Fts5Index *pIndex = pIter->pIndex;
+    fts5MultiIterFree(pIter);
+    fts5CloseReader(pIndex);
+  }
+}
+
+/*
+** Read and decode the "averages" record from the database. 
+**
+** Parameter anSize must point to an array of size nCol, where nCol is
+** the number of user defined columns in the FTS table.
+*/
+static int sqlite3Fts5IndexGetAverages(Fts5Index *p, i64 *pnRow, i64 *anSize){
+  int nCol = p->pConfig->nCol;
+  Fts5Data *pData;
+
+  *pnRow = 0;
+  memset(anSize, 0, sizeof(i64) * nCol);
+  pData = fts5DataRead(p, FTS5_AVERAGES_ROWID);
+  if( p->rc==SQLITE_OK && pData->nn ){
+    int i = 0;
+    int iCol;
+    i += fts5GetVarint(&pData->p[i], (u64*)pnRow);
+    for(iCol=0; i<pData->nn && iCol<nCol; iCol++){
+      i += fts5GetVarint(&pData->p[i], (u64*)&anSize[iCol]);
+    }
+  }
+
+  fts5DataRelease(pData);
+  return fts5IndexReturn(p);
+}
+
+/*
+** Replace the current "averages" record with the contents of the buffer 
+** supplied as the second argument.
+*/
+static int sqlite3Fts5IndexSetAverages(Fts5Index *p, const u8 *pData, int nData){
+  assert( p->rc==SQLITE_OK );
+  fts5DataWrite(p, FTS5_AVERAGES_ROWID, pData, nData);
+  return fts5IndexReturn(p);
+}
+
+/*
+** Return the total number of blocks this module has read from the %_data
+** table since it was created.
+*/
+static int sqlite3Fts5IndexReads(Fts5Index *p){
+  return p->nRead;
+}
+
+/*
+** Set the 32-bit cookie value stored at the start of all structure 
+** records to the value passed as the second argument.
+**
+** Return SQLITE_OK if successful, or an SQLite error code if an error
+** occurs.
+*/
+static int sqlite3Fts5IndexSetCookie(Fts5Index *p, int iNew){
+  int rc;                              /* Return code */
+  Fts5Config *pConfig = p->pConfig;    /* Configuration object */
+  u8 aCookie[4];                       /* Binary representation of iNew */
+  sqlite3_blob *pBlob = 0;
+
+  assert( p->rc==SQLITE_OK );
+  sqlite3Fts5Put32(aCookie, iNew);
+
+  rc = sqlite3_blob_open(pConfig->db, pConfig->zDb, p->zDataTbl, 
+      "block", FTS5_STRUCTURE_ROWID, 1, &pBlob
+  );
+  if( rc==SQLITE_OK ){
+    sqlite3_blob_write(pBlob, aCookie, 4, 0);
+    rc = sqlite3_blob_close(pBlob);
+  }
+
+  return rc;
+}
+
+static int sqlite3Fts5IndexLoadConfig(Fts5Index *p){
+  Fts5Structure *pStruct;
+  pStruct = fts5StructureRead(p);
+  fts5StructureRelease(pStruct);
+  return fts5IndexReturn(p);
+}
+
+
+/*************************************************************************
+**************************************************************************
+** Below this point is the implementation of the integrity-check 
+** functionality.
+*/
+
+/*
+** Return a simple checksum value based on the arguments.
+*/
+static u64 sqlite3Fts5IndexEntryCksum(
+  i64 iRowid, 
+  int iCol, 
+  int iPos, 
+  int iIdx,
+  const char *pTerm,
+  int nTerm
+){
+  int i;
+  u64 ret = iRowid;
+  ret += (ret<<3) + iCol;
+  ret += (ret<<3) + iPos;
+  if( iIdx>=0 ) ret += (ret<<3) + (FTS5_MAIN_PREFIX + iIdx);
+  for(i=0; i<nTerm; i++) ret += (ret<<3) + pTerm[i];
+  return ret;
+}
+
+#ifdef SQLITE_DEBUG
+/*
+** This function is purely an internal test. It does not contribute to 
+** FTS functionality, or even the integrity-check, in any way.
+**
+** Instead, it tests that the same set of pgno/rowid combinations are 
+** visited regardless of whether the doclist-index identified by parameters
+** iSegid/iLeaf is iterated in forwards or reverse order.
+*/
+static void fts5TestDlidxReverse(
+  Fts5Index *p, 
+  int iSegid,                     /* Segment id to load from */
+  int iLeaf                       /* Load doclist-index for this leaf */
+){
+  Fts5DlidxIter *pDlidx = 0;
+  u64 cksum1 = 13;
+  u64 cksum2 = 13;
+
+  for(pDlidx=fts5DlidxIterInit(p, 0, iSegid, iLeaf);
+      fts5DlidxIterEof(p, pDlidx)==0;
+      fts5DlidxIterNext(p, pDlidx)
+  ){
+    i64 iRowid = fts5DlidxIterRowid(pDlidx);
+    int pgno = fts5DlidxIterPgno(pDlidx);
+    assert( pgno>iLeaf );
+    cksum1 += iRowid + ((i64)pgno<<32);
+  }
+  fts5DlidxIterFree(pDlidx);
+  pDlidx = 0;
+
+  for(pDlidx=fts5DlidxIterInit(p, 1, iSegid, iLeaf);
+      fts5DlidxIterEof(p, pDlidx)==0;
+      fts5DlidxIterPrev(p, pDlidx)
+  ){
+    i64 iRowid = fts5DlidxIterRowid(pDlidx);
+    int pgno = fts5DlidxIterPgno(pDlidx);
+    assert( fts5DlidxIterPgno(pDlidx)>iLeaf );
+    cksum2 += iRowid + ((i64)pgno<<32);
+  }
+  fts5DlidxIterFree(pDlidx);
+  pDlidx = 0;
+
+  if( p->rc==SQLITE_OK && cksum1!=cksum2 ) p->rc = FTS5_CORRUPT;
+}
+
+static int fts5QueryCksum(
+  Fts5Index *p,                   /* Fts5 index object */
+  int iIdx,
+  const char *z,                  /* Index key to query for */
+  int n,                          /* Size of index key in bytes */
+  int flags,                      /* Flags for Fts5IndexQuery */
+  u64 *pCksum                     /* IN/OUT: Checksum value */
+){
+  int eDetail = p->pConfig->eDetail;
+  u64 cksum = *pCksum;
+  Fts5IndexIter *pIter = 0;
+  int rc = sqlite3Fts5IndexQuery(p, z, n, flags, 0, &pIter);
+
+  while( rc==SQLITE_OK && 0==sqlite3Fts5IterEof(pIter) ){
+    i64 rowid = pIter->iRowid;
+
+    if( eDetail==FTS5_DETAIL_NONE ){
+      cksum ^= sqlite3Fts5IndexEntryCksum(rowid, 0, 0, iIdx, z, n);
+    }else{
+      Fts5PoslistReader sReader;
+      for(sqlite3Fts5PoslistReaderInit(pIter->pData, pIter->nData, &sReader);
+          sReader.bEof==0;
+          sqlite3Fts5PoslistReaderNext(&sReader)
+      ){
+        int iCol = FTS5_POS2COLUMN(sReader.iPos);
+        int iOff = FTS5_POS2OFFSET(sReader.iPos);
+        cksum ^= sqlite3Fts5IndexEntryCksum(rowid, iCol, iOff, iIdx, z, n);
+      }
+    }
+    if( rc==SQLITE_OK ){
+      rc = sqlite3Fts5IterNext(pIter);
+    }
+  }
+  sqlite3Fts5IterClose(pIter);
+
+  *pCksum = cksum;
+  return rc;
+}
+
+
+/*
+** This function is also purely an internal test. It does not contribute to 
+** FTS functionality, or even the integrity-check, in any way.
+*/
+static void fts5TestTerm(
+  Fts5Index *p, 
+  Fts5Buffer *pPrev,              /* Previous term */
+  const char *z, int n,           /* Possibly new term to test */
+  u64 expected,
+  u64 *pCksum
+){
+  int rc = p->rc;
+  if( pPrev->n==0 ){
+    fts5BufferSet(&rc, pPrev, n, (const u8*)z);
+  }else
+  if( rc==SQLITE_OK && (pPrev->n!=n || memcmp(pPrev->p, z, n)) ){
+    u64 cksum3 = *pCksum;
+    const char *zTerm = (const char*)&pPrev->p[1];  /* term sans prefix-byte */
+    int nTerm = pPrev->n-1;            /* Size of zTerm in bytes */
+    int iIdx = (pPrev->p[0] - FTS5_MAIN_PREFIX);
+    int flags = (iIdx==0 ? 0 : FTS5INDEX_QUERY_PREFIX);
+    u64 ck1 = 0;
+    u64 ck2 = 0;
+
+    /* Check that the results returned for ASC and DESC queries are
+    ** the same. If not, call this corruption.  */
+    rc = fts5QueryCksum(p, iIdx, zTerm, nTerm, flags, &ck1);
+    if( rc==SQLITE_OK ){
+      int f = flags|FTS5INDEX_QUERY_DESC;
+      rc = fts5QueryCksum(p, iIdx, zTerm, nTerm, f, &ck2);
+    }
+    if( rc==SQLITE_OK && ck1!=ck2 ) rc = FTS5_CORRUPT;
+
+    /* If this is a prefix query, check that the results returned if the
+    ** the index is disabled are the same. In both ASC and DESC order. 
+    **
+    ** This check may only be performed if the hash table is empty. This
+    ** is because the hash table only supports a single scan query at
+    ** a time, and the multi-iter loop from which this function is called
+    ** is already performing such a scan. */
+    if( p->nPendingData==0 ){
+      if( iIdx>0 && rc==SQLITE_OK ){
+        int f = flags|FTS5INDEX_QUERY_TEST_NOIDX;
+        ck2 = 0;
+        rc = fts5QueryCksum(p, iIdx, zTerm, nTerm, f, &ck2);
+        if( rc==SQLITE_OK && ck1!=ck2 ) rc = FTS5_CORRUPT;
+      }
+      if( iIdx>0 && rc==SQLITE_OK ){
+        int f = flags|FTS5INDEX_QUERY_TEST_NOIDX|FTS5INDEX_QUERY_DESC;
+        ck2 = 0;
+        rc = fts5QueryCksum(p, iIdx, zTerm, nTerm, f, &ck2);
+        if( rc==SQLITE_OK && ck1!=ck2 ) rc = FTS5_CORRUPT;
+      }
+    }
+
+    cksum3 ^= ck1;
+    fts5BufferSet(&rc, pPrev, n, (const u8*)z);
+
+    if( rc==SQLITE_OK && cksum3!=expected ){
+      rc = FTS5_CORRUPT;
+    }
+    *pCksum = cksum3;
+  }
+  p->rc = rc;
+}
+ 
+#else
+# define fts5TestDlidxReverse(x,y,z)
+# define fts5TestTerm(u,v,w,x,y,z)
+#endif
+
+/*
+** Check that:
+**
+**   1) All leaves of pSeg between iFirst and iLast (inclusive) exist and
+**      contain zero terms.
+**   2) All leaves of pSeg between iNoRowid and iLast (inclusive) exist and
+**      contain zero rowids.
+*/
+static void fts5IndexIntegrityCheckEmpty(
+  Fts5Index *p,
+  Fts5StructureSegment *pSeg,     /* Segment to check internal consistency */
+  int iFirst,
+  int iNoRowid,
+  int iLast
+){
+  int i;
+
+  /* Now check that the iter.nEmpty leaves following the current leaf
+  ** (a) exist and (b) contain no terms. */
+  for(i=iFirst; p->rc==SQLITE_OK && i<=iLast; i++){
+    Fts5Data *pLeaf = fts5DataRead(p, FTS5_SEGMENT_ROWID(pSeg->iSegid, i));
+    if( pLeaf ){
+      if( !fts5LeafIsTermless(pLeaf) ) p->rc = FTS5_CORRUPT;
+      if( i>=iNoRowid && 0!=fts5LeafFirstRowidOff(pLeaf) ) p->rc = FTS5_CORRUPT;
+    }
+    fts5DataRelease(pLeaf);
+  }
+}
+
+static void fts5IntegrityCheckPgidx(Fts5Index *p, Fts5Data *pLeaf){
+  int iTermOff = 0;
+  int ii;
+
+  Fts5Buffer buf1 = {0,0,0};
+  Fts5Buffer buf2 = {0,0,0};
+
+  ii = pLeaf->szLeaf;
+  while( ii<pLeaf->nn && p->rc==SQLITE_OK ){
+    int res;
+    int iOff;
+    int nIncr;
+
+    ii += fts5GetVarint32(&pLeaf->p[ii], nIncr);
+    iTermOff += nIncr;
+    iOff = iTermOff;
+
+    if( iOff>=pLeaf->szLeaf ){
+      p->rc = FTS5_CORRUPT;
+    }else if( iTermOff==nIncr ){
+      int nByte;
+      iOff += fts5GetVarint32(&pLeaf->p[iOff], nByte);
+      if( (iOff+nByte)>pLeaf->szLeaf ){
+        p->rc = FTS5_CORRUPT;
+      }else{
+        fts5BufferSet(&p->rc, &buf1, nByte, &pLeaf->p[iOff]);
+      }
+    }else{
+      int nKeep, nByte;
+      iOff += fts5GetVarint32(&pLeaf->p[iOff], nKeep);
+      iOff += fts5GetVarint32(&pLeaf->p[iOff], nByte);
+      if( nKeep>buf1.n || (iOff+nByte)>pLeaf->szLeaf ){
+        p->rc = FTS5_CORRUPT;
+      }else{
+        buf1.n = nKeep;
+        fts5BufferAppendBlob(&p->rc, &buf1, nByte, &pLeaf->p[iOff]);
+      }
+
+      if( p->rc==SQLITE_OK ){
+        res = fts5BufferCompare(&buf1, &buf2);
+        if( res<=0 ) p->rc = FTS5_CORRUPT;
+      }
+    }
+    fts5BufferSet(&p->rc, &buf2, buf1.n, buf1.p);
+  }
+
+  fts5BufferFree(&buf1);
+  fts5BufferFree(&buf2);
+}
+
+static void fts5IndexIntegrityCheckSegment(
+  Fts5Index *p,                   /* FTS5 backend object */
+  Fts5StructureSegment *pSeg      /* Segment to check internal consistency */
+){
+  Fts5Config *pConfig = p->pConfig;
+  sqlite3_stmt *pStmt = 0;
+  int rc2;
+  int iIdxPrevLeaf = pSeg->pgnoFirst-1;
+  int iDlidxPrevLeaf = pSeg->pgnoLast;
+
+  if( pSeg->pgnoFirst==0 ) return;
+
+  fts5IndexPrepareStmt(p, &pStmt, sqlite3_mprintf(
+      "SELECT segid, term, (pgno>>1), (pgno&1) FROM %Q.'%q_idx' WHERE segid=%d",
+      pConfig->zDb, pConfig->zName, pSeg->iSegid
+  ));
+
+  /* Iterate through the b-tree hierarchy.  */
+  while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
+    i64 iRow;                     /* Rowid for this leaf */
+    Fts5Data *pLeaf;              /* Data for this leaf */
+
+    int nIdxTerm = sqlite3_column_bytes(pStmt, 1);
+    const char *zIdxTerm = (const char*)sqlite3_column_text(pStmt, 1);
+    int iIdxLeaf = sqlite3_column_int(pStmt, 2);
+    int bIdxDlidx = sqlite3_column_int(pStmt, 3);
+
+    /* If the leaf in question has already been trimmed from the segment, 
+    ** ignore this b-tree entry. Otherwise, load it into memory. */
+    if( iIdxLeaf<pSeg->pgnoFirst ) continue;
+    iRow = FTS5_SEGMENT_ROWID(pSeg->iSegid, iIdxLeaf);
+    pLeaf = fts5DataRead(p, iRow);
+    if( pLeaf==0 ) break;
+
+    /* Check that the leaf contains at least one term, and that it is equal
+    ** to or larger than the split-key in zIdxTerm.  Also check that if there
+    ** is also a rowid pointer within the leaf page header, it points to a
+    ** location before the term.  */
+    if( pLeaf->nn<=pLeaf->szLeaf ){
+      p->rc = FTS5_CORRUPT;
+    }else{
+      int iOff;                   /* Offset of first term on leaf */
+      int iRowidOff;              /* Offset of first rowid on leaf */
+      int nTerm;                  /* Size of term on leaf in bytes */
+      int res;                    /* Comparison of term and split-key */
+
+      iOff = fts5LeafFirstTermOff(pLeaf);
+      iRowidOff = fts5LeafFirstRowidOff(pLeaf);
+      if( iRowidOff>=iOff ){
+        p->rc = FTS5_CORRUPT;
+      }else{
+        iOff += fts5GetVarint32(&pLeaf->p[iOff], nTerm);
+        res = memcmp(&pLeaf->p[iOff], zIdxTerm, MIN(nTerm, nIdxTerm));
+        if( res==0 ) res = nTerm - nIdxTerm;
+        if( res<0 ) p->rc = FTS5_CORRUPT;
+      }
+
+      fts5IntegrityCheckPgidx(p, pLeaf);
+    }
+    fts5DataRelease(pLeaf);
+    if( p->rc ) break;
+
+    /* Now check that the iter.nEmpty leaves following the current leaf
+    ** (a) exist and (b) contain no terms. */
+    fts5IndexIntegrityCheckEmpty(
+        p, pSeg, iIdxPrevLeaf+1, iDlidxPrevLeaf+1, iIdxLeaf-1
+    );
+    if( p->rc ) break;
+
+    /* If there is a doclist-index, check that it looks right. */
+    if( bIdxDlidx ){
+      Fts5DlidxIter *pDlidx = 0;  /* For iterating through doclist index */
+      int iPrevLeaf = iIdxLeaf;
+      int iSegid = pSeg->iSegid;
+      int iPg = 0;
+      i64 iKey;
+
+      for(pDlidx=fts5DlidxIterInit(p, 0, iSegid, iIdxLeaf);
+          fts5DlidxIterEof(p, pDlidx)==0;
+          fts5DlidxIterNext(p, pDlidx)
+      ){
+
+        /* Check any rowid-less pages that occur before the current leaf. */
+        for(iPg=iPrevLeaf+1; iPg<fts5DlidxIterPgno(pDlidx); iPg++){
+          iKey = FTS5_SEGMENT_ROWID(iSegid, iPg);
+          pLeaf = fts5DataRead(p, iKey);
+          if( pLeaf ){
+            if( fts5LeafFirstRowidOff(pLeaf)!=0 ) p->rc = FTS5_CORRUPT;
+            fts5DataRelease(pLeaf);
+          }
+        }
+        iPrevLeaf = fts5DlidxIterPgno(pDlidx);
+
+        /* Check that the leaf page indicated by the iterator really does
+        ** contain the rowid suggested by the same. */
+        iKey = FTS5_SEGMENT_ROWID(iSegid, iPrevLeaf);
+        pLeaf = fts5DataRead(p, iKey);
+        if( pLeaf ){
+          i64 iRowid;
+          int iRowidOff = fts5LeafFirstRowidOff(pLeaf);
+          ASSERT_SZLEAF_OK(pLeaf);
+          if( iRowidOff>=pLeaf->szLeaf ){
+            p->rc = FTS5_CORRUPT;
+          }else{
+            fts5GetVarint(&pLeaf->p[iRowidOff], (u64*)&iRowid);
+            if( iRowid!=fts5DlidxIterRowid(pDlidx) ) p->rc = FTS5_CORRUPT;
+          }
+          fts5DataRelease(pLeaf);
+        }
+      }
+
+      iDlidxPrevLeaf = iPg;
+      fts5DlidxIterFree(pDlidx);
+      fts5TestDlidxReverse(p, iSegid, iIdxLeaf);
+    }else{
+      iDlidxPrevLeaf = pSeg->pgnoLast;
+      /* TODO: Check there is no doclist index */
+    }
+
+    iIdxPrevLeaf = iIdxLeaf;
+  }
+
+  rc2 = sqlite3_finalize(pStmt);
+  if( p->rc==SQLITE_OK ) p->rc = rc2;
+
+  /* Page iter.iLeaf must now be the rightmost leaf-page in the segment */
+#if 0
+  if( p->rc==SQLITE_OK && iter.iLeaf!=pSeg->pgnoLast ){
+    p->rc = FTS5_CORRUPT;
+  }
+#endif
+}
+
+
+/*
+** Run internal checks to ensure that the FTS index (a) is internally 
+** consistent and (b) contains entries for which the XOR of the checksums
+** as calculated by sqlite3Fts5IndexEntryCksum() is cksum.
+**
+** Return SQLITE_CORRUPT if any of the internal checks fail, or if the
+** checksum does not match. Return SQLITE_OK if all checks pass without
+** error, or some other SQLite error code if another error (e.g. OOM)
+** occurs.
+*/
+static int sqlite3Fts5IndexIntegrityCheck(Fts5Index *p, u64 cksum){
+  int eDetail = p->pConfig->eDetail;
+  u64 cksum2 = 0;                 /* Checksum based on contents of indexes */
+  Fts5Buffer poslist = {0,0,0};   /* Buffer used to hold a poslist */
+  Fts5Iter *pIter;                /* Used to iterate through entire index */
+  Fts5Structure *pStruct;         /* Index structure */
+
+#ifdef SQLITE_DEBUG
+  /* Used by extra internal tests only run if NDEBUG is not defined */
+  u64 cksum3 = 0;                 /* Checksum based on contents of indexes */
+  Fts5Buffer term = {0,0,0};      /* Buffer used to hold most recent term */
+#endif
+  const int flags = FTS5INDEX_QUERY_NOOUTPUT;
+  
+  /* Load the FTS index structure */
+  pStruct = fts5StructureRead(p);
+
+  /* Check that the internal nodes of each segment match the leaves */
+  if( pStruct ){
+    int iLvl, iSeg;
+    for(iLvl=0; iLvl<pStruct->nLevel; iLvl++){
+      for(iSeg=0; iSeg<pStruct->aLevel[iLvl].nSeg; iSeg++){
+        Fts5StructureSegment *pSeg = &pStruct->aLevel[iLvl].aSeg[iSeg];
+        fts5IndexIntegrityCheckSegment(p, pSeg);
+      }
+    }
+  }
+
+  /* The cksum argument passed to this function is a checksum calculated
+  ** based on all expected entries in the FTS index (including prefix index
+  ** entries). This block checks that a checksum calculated based on the
+  ** actual contents of FTS index is identical.
+  **
+  ** Two versions of the same checksum are calculated. The first (stack
+  ** variable cksum2) based on entries extracted from the full-text index
+  ** while doing a linear scan of each individual index in turn. 
+  **
+  ** As each term visited by the linear scans, a separate query for the
+  ** same term is performed. cksum3 is calculated based on the entries
+  ** extracted by these queries.
+  */
+  for(fts5MultiIterNew(p, pStruct, flags, 0, 0, 0, -1, 0, &pIter);
+      fts5MultiIterEof(p, pIter)==0;
+      fts5MultiIterNext(p, pIter, 0, 0)
+  ){
+    int n;                      /* Size of term in bytes */
+    i64 iPos = 0;               /* Position read from poslist */
+    int iOff = 0;               /* Offset within poslist */
+    i64 iRowid = fts5MultiIterRowid(pIter);
+    char *z = (char*)fts5MultiIterTerm(pIter, &n);
+
+    /* If this is a new term, query for it. Update cksum3 with the results. */
+    fts5TestTerm(p, &term, z, n, cksum2, &cksum3);
+
+    if( eDetail==FTS5_DETAIL_NONE ){
+      if( 0==fts5MultiIterIsEmpty(p, pIter) ){
+        cksum2 ^= sqlite3Fts5IndexEntryCksum(iRowid, 0, 0, -1, z, n);
+      }
+    }else{
+      poslist.n = 0;
+      fts5SegiterPoslist(p, &pIter->aSeg[pIter->aFirst[1].iFirst], 0, &poslist);
+      while( 0==sqlite3Fts5PoslistNext64(poslist.p, poslist.n, &iOff, &iPos) ){
+        int iCol = FTS5_POS2COLUMN(iPos);
+        int iTokOff = FTS5_POS2OFFSET(iPos);
+        cksum2 ^= sqlite3Fts5IndexEntryCksum(iRowid, iCol, iTokOff, -1, z, n);
+      }
+    }
+  }
+  fts5TestTerm(p, &term, 0, 0, cksum2, &cksum3);
+
+  fts5MultiIterFree(pIter);
+  if( p->rc==SQLITE_OK && cksum!=cksum2 ) p->rc = FTS5_CORRUPT;
+
+  fts5StructureRelease(pStruct);
+#ifdef SQLITE_DEBUG
+  fts5BufferFree(&term);
+#endif
+  fts5BufferFree(&poslist);
+  return fts5IndexReturn(p);
+}
+
+/*************************************************************************
+**************************************************************************
+** Below this point is the implementation of the fts5_decode() scalar
+** function only.
+*/
+
+/*
+** Decode a segment-data rowid from the %_data table. This function is
+** the opposite of macro FTS5_SEGMENT_ROWID().
+*/
+static void fts5DecodeRowid(
+  i64 iRowid,                     /* Rowid from %_data table */
+  int *piSegid,                   /* OUT: Segment id */
+  int *pbDlidx,                   /* OUT: Dlidx flag */
+  int *piHeight,                  /* OUT: Height */
+  int *piPgno                     /* OUT: Page number */
+){
+  *piPgno = (int)(iRowid & (((i64)1 << FTS5_DATA_PAGE_B) - 1));
+  iRowid >>= FTS5_DATA_PAGE_B;
+
+  *piHeight = (int)(iRowid & (((i64)1 << FTS5_DATA_HEIGHT_B) - 1));
+  iRowid >>= FTS5_DATA_HEIGHT_B;
+
+  *pbDlidx = (int)(iRowid & 0x0001);
+  iRowid >>= FTS5_DATA_DLI_B;
+
+  *piSegid = (int)(iRowid & (((i64)1 << FTS5_DATA_ID_B) - 1));
+}
+
+static void fts5DebugRowid(int *pRc, Fts5Buffer *pBuf, i64 iKey){
+  int iSegid, iHeight, iPgno, bDlidx;       /* Rowid compenents */
+  fts5DecodeRowid(iKey, &iSegid, &bDlidx, &iHeight, &iPgno);
+
+  if( iSegid==0 ){
+    if( iKey==FTS5_AVERAGES_ROWID ){
+      sqlite3Fts5BufferAppendPrintf(pRc, pBuf, "{averages} ");
+    }else{
+      sqlite3Fts5BufferAppendPrintf(pRc, pBuf, "{structure}");
+    }
+  }
+  else{
+    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, "{%ssegid=%d h=%d pgno=%d}",
+        bDlidx ? "dlidx " : "", iSegid, iHeight, iPgno
+    );
+  }
+}
+
+static void fts5DebugStructure(
+  int *pRc,                       /* IN/OUT: error code */
+  Fts5Buffer *pBuf,
+  Fts5Structure *p
+){
+  int iLvl, iSeg;                 /* Iterate through levels, segments */
+
+  for(iLvl=0; iLvl<p->nLevel; iLvl++){
+    Fts5StructureLevel *pLvl = &p->aLevel[iLvl];
+    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, 
+        " {lvl=%d nMerge=%d nSeg=%d", iLvl, pLvl->nMerge, pLvl->nSeg
+    );
+    for(iSeg=0; iSeg<pLvl->nSeg; iSeg++){
+      Fts5StructureSegment *pSeg = &pLvl->aSeg[iSeg];
+      sqlite3Fts5BufferAppendPrintf(pRc, pBuf, " {id=%d leaves=%d..%d}", 
+          pSeg->iSegid, pSeg->pgnoFirst, pSeg->pgnoLast
+      );
+    }
+    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, "}");
+  }
+}
+
+/*
+** This is part of the fts5_decode() debugging aid.
+**
+** Arguments pBlob/nBlob contain a serialized Fts5Structure object. This
+** function appends a human-readable representation of the same object
+** to the buffer passed as the second argument. 
+*/
+static void fts5DecodeStructure(
+  int *pRc,                       /* IN/OUT: error code */
+  Fts5Buffer *pBuf,
+  const u8 *pBlob, int nBlob
+){
+  int rc;                         /* Return code */
+  Fts5Structure *p = 0;           /* Decoded structure object */
+
+  rc = fts5StructureDecode(pBlob, nBlob, 0, &p);
+  if( rc!=SQLITE_OK ){
+    *pRc = rc;
+    return;
+  }
+
+  fts5DebugStructure(pRc, pBuf, p);
+  fts5StructureRelease(p);
+}
+
+/*
+** This is part of the fts5_decode() debugging aid.
+**
+** Arguments pBlob/nBlob contain an "averages" record. This function 
+** appends a human-readable representation of record to the buffer passed 
+** as the second argument. 
+*/
+static void fts5DecodeAverages(
+  int *pRc,                       /* IN/OUT: error code */
+  Fts5Buffer *pBuf,
+  const u8 *pBlob, int nBlob
+){
+  int i = 0;
+  const char *zSpace = "";
+
+  while( i<nBlob ){
+    u64 iVal;
+    i += sqlite3Fts5GetVarint(&pBlob[i], &iVal);
+    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, "%s%d", zSpace, (int)iVal);
+    zSpace = " ";
+  }
+}
+
+/*
+** Buffer (a/n) is assumed to contain a list of serialized varints. Read
+** each varint and append its string representation to buffer pBuf. Return
+** after either the input buffer is exhausted or a 0 value is read.
+**
+** The return value is the number of bytes read from the input buffer.
+*/
+static int fts5DecodePoslist(int *pRc, Fts5Buffer *pBuf, const u8 *a, int n){
+  int iOff = 0;
+  while( iOff<n ){
+    int iVal;
+    iOff += fts5GetVarint32(&a[iOff], iVal);
+    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, " %d", iVal);
+  }
+  return iOff;
+}
+
+/*
+** The start of buffer (a/n) contains the start of a doclist. The doclist
+** may or may not finish within the buffer. This function appends a text
+** representation of the part of the doclist that is present to buffer
+** pBuf. 
+**
+** The return value is the number of bytes read from the input buffer.
+*/
+static int fts5DecodeDoclist(int *pRc, Fts5Buffer *pBuf, const u8 *a, int n){
+  i64 iDocid = 0;
+  int iOff = 0;
+
+  if( n>0 ){
+    iOff = sqlite3Fts5GetVarint(a, (u64*)&iDocid);
+    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, " id=%lld", iDocid);
+  }
+  while( iOff<n ){
+    int nPos;
+    int bDel;
+    iOff += fts5GetPoslistSize(&a[iOff], &nPos, &bDel);
+    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, " nPos=%d%s", nPos, bDel?"*":"");
+    iOff += fts5DecodePoslist(pRc, pBuf, &a[iOff], MIN(n-iOff, nPos));
+    if( iOff<n ){
+      i64 iDelta;
+      iOff += sqlite3Fts5GetVarint(&a[iOff], (u64*)&iDelta);
+      iDocid += iDelta;
+      sqlite3Fts5BufferAppendPrintf(pRc, pBuf, " id=%lld", iDocid);
+    }
+  }
+
+  return iOff;
+}
+
+/*
+** This function is part of the fts5_decode() debugging function. It is 
+** only ever used with detail=none tables.
+**
+** Buffer (pData/nData) contains a doclist in the format used by detail=none
+** tables. This function appends a human-readable version of that list to
+** buffer pBuf.
+**
+** If *pRc is other than SQLITE_OK when this function is called, it is a
+** no-op. If an OOM or other error occurs within this function, *pRc is
+** set to an SQLite error code before returning. The final state of buffer
+** pBuf is undefined in this case.
+*/
+static void fts5DecodeRowidList(
+  int *pRc,                       /* IN/OUT: Error code */
+  Fts5Buffer *pBuf,               /* Buffer to append text to */
+  const u8 *pData, int nData      /* Data to decode list-of-rowids from */
+){
+  int i = 0;
+  i64 iRowid = 0;
+
+  while( i<nData ){
+    const char *zApp = "";
+    u64 iVal;
+    i += sqlite3Fts5GetVarint(&pData[i], &iVal);
+    iRowid += iVal;
+
+    if( i<nData && pData[i]==0x00 ){
+      i++;
+      if( i<nData && pData[i]==0x00 ){
+        i++;
+        zApp = "+";
+      }else{
+        zApp = "*";
+      }
+    }
+
+    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, " %lld%s", iRowid, zApp);
+  }
+}
+
+/*
+** The implementation of user-defined scalar function fts5_decode().
+*/
+static void fts5DecodeFunction(
+  sqlite3_context *pCtx,          /* Function call context */
+  int nArg,                       /* Number of args (always 2) */
+  sqlite3_value **apVal           /* Function arguments */
+){
+  i64 iRowid;                     /* Rowid for record being decoded */
+  int iSegid,iHeight,iPgno,bDlidx;/* Rowid components */
+  const u8 *aBlob; int n;         /* Record to decode */
+  u8 *a = 0;
+  Fts5Buffer s;                   /* Build up text to return here */
+  int rc = SQLITE_OK;             /* Return code */
+  int nSpace = 0;
+  int eDetailNone = (sqlite3_user_data(pCtx)!=0);
+
+  assert( nArg==2 );
+  UNUSED_PARAM(nArg);
+  memset(&s, 0, sizeof(Fts5Buffer));
+  iRowid = sqlite3_value_int64(apVal[0]);
+
+  /* Make a copy of the second argument (a blob) in aBlob[]. The aBlob[]
+  ** copy is followed by FTS5_DATA_ZERO_PADDING 0x00 bytes, which prevents
+  ** buffer overreads even if the record is corrupt.  */
+  n = sqlite3_value_bytes(apVal[1]);
+  aBlob = sqlite3_value_blob(apVal[1]);
+  nSpace = n + FTS5_DATA_ZERO_PADDING;
+  a = (u8*)sqlite3Fts5MallocZero(&rc, nSpace);
+  if( a==0 ) goto decode_out;
+  memcpy(a, aBlob, n);
+
+
+  fts5DecodeRowid(iRowid, &iSegid, &bDlidx, &iHeight, &iPgno);
+
+  fts5DebugRowid(&rc, &s, iRowid);
+  if( bDlidx ){
+    Fts5Data dlidx;
+    Fts5DlidxLvl lvl;
+
+    dlidx.p = a;
+    dlidx.nn = n;
+
+    memset(&lvl, 0, sizeof(Fts5DlidxLvl));
+    lvl.pData = &dlidx;
+    lvl.iLeafPgno = iPgno;
+
+    for(fts5DlidxLvlNext(&lvl); lvl.bEof==0; fts5DlidxLvlNext(&lvl)){
+      sqlite3Fts5BufferAppendPrintf(&rc, &s, 
+          " %d(%lld)", lvl.iLeafPgno, lvl.iRowid
+      );
+    }
+  }else if( iSegid==0 ){
+    if( iRowid==FTS5_AVERAGES_ROWID ){
+      fts5DecodeAverages(&rc, &s, a, n);
+    }else{
+      fts5DecodeStructure(&rc, &s, a, n);
+    }
+  }else if( eDetailNone ){
+    Fts5Buffer term;              /* Current term read from page */
+    int szLeaf;
+    int iPgidxOff = szLeaf = fts5GetU16(&a[2]);
+    int iTermOff;
+    int nKeep = 0;
+    int iOff;
+
+    memset(&term, 0, sizeof(Fts5Buffer));
+
+    /* Decode any entries that occur before the first term. */
+    if( szLeaf<n ){
+      iPgidxOff += fts5GetVarint32(&a[iPgidxOff], iTermOff);
+    }else{
+      iTermOff = szLeaf;
+    }
+    fts5DecodeRowidList(&rc, &s, &a[4], iTermOff-4);
+
+    iOff = iTermOff;
+    while( iOff<szLeaf ){
+      int nAppend;
+
+      /* Read the term data for the next term*/
+      iOff += fts5GetVarint32(&a[iOff], nAppend);
+      term.n = nKeep;
+      fts5BufferAppendBlob(&rc, &term, nAppend, &a[iOff]);
+      sqlite3Fts5BufferAppendPrintf(
+          &rc, &s, " term=%.*s", term.n, (const char*)term.p
+      );
+      iOff += nAppend;
+
+      /* Figure out where the doclist for this term ends */
+      if( iPgidxOff<n ){
+        int nIncr;
+        iPgidxOff += fts5GetVarint32(&a[iPgidxOff], nIncr);
+        iTermOff += nIncr;
+      }else{
+        iTermOff = szLeaf;
+      }
+
+      fts5DecodeRowidList(&rc, &s, &a[iOff], iTermOff-iOff);
+      iOff = iTermOff;
+      if( iOff<szLeaf ){
+        iOff += fts5GetVarint32(&a[iOff], nKeep);
+      }
+    }
+
+    fts5BufferFree(&term);
+  }else{
+    Fts5Buffer term;              /* Current term read from page */
+    int szLeaf;                   /* Offset of pgidx in a[] */
+    int iPgidxOff;
+    int iPgidxPrev = 0;           /* Previous value read from pgidx */
+    int iTermOff = 0;
+    int iRowidOff = 0;
+    int iOff;
+    int nDoclist;
+
+    memset(&term, 0, sizeof(Fts5Buffer));
+
+    if( n<4 ){
+      sqlite3Fts5BufferSet(&rc, &s, 7, (const u8*)"corrupt");
+      goto decode_out;
+    }else{
+      iRowidOff = fts5GetU16(&a[0]);
+      iPgidxOff = szLeaf = fts5GetU16(&a[2]);
+      if( iPgidxOff<n ){
+        fts5GetVarint32(&a[iPgidxOff], iTermOff);
+      }
+    }
+
+    /* Decode the position list tail at the start of the page */
+    if( iRowidOff!=0 ){
+      iOff = iRowidOff;
+    }else if( iTermOff!=0 ){
+      iOff = iTermOff;
+    }else{
+      iOff = szLeaf;
+    }
+    fts5DecodePoslist(&rc, &s, &a[4], iOff-4);
+
+    /* Decode any more doclist data that appears on the page before the
+    ** first term. */
+    nDoclist = (iTermOff ? iTermOff : szLeaf) - iOff;
+    fts5DecodeDoclist(&rc, &s, &a[iOff], nDoclist);
+
+    while( iPgidxOff<n ){
+      int bFirst = (iPgidxOff==szLeaf);     /* True for first term on page */
+      int nByte;                            /* Bytes of data */
+      int iEnd;
+      
+      iPgidxOff += fts5GetVarint32(&a[iPgidxOff], nByte);
+      iPgidxPrev += nByte;
+      iOff = iPgidxPrev;
+
+      if( iPgidxOff<n ){
+        fts5GetVarint32(&a[iPgidxOff], nByte);
+        iEnd = iPgidxPrev + nByte;
+      }else{
+        iEnd = szLeaf;
+      }
+
+      if( bFirst==0 ){
+        iOff += fts5GetVarint32(&a[iOff], nByte);
+        term.n = nByte;
+      }
+      iOff += fts5GetVarint32(&a[iOff], nByte);
+      fts5BufferAppendBlob(&rc, &term, nByte, &a[iOff]);
+      iOff += nByte;
+
+      sqlite3Fts5BufferAppendPrintf(
+          &rc, &s, " term=%.*s", term.n, (const char*)term.p
+      );
+      iOff += fts5DecodeDoclist(&rc, &s, &a[iOff], iEnd-iOff);
+    }
+
+    fts5BufferFree(&term);
+  }
+  
+ decode_out:
+  sqlite3_free(a);
+  if( rc==SQLITE_OK ){
+    sqlite3_result_text(pCtx, (const char*)s.p, s.n, SQLITE_TRANSIENT);
+  }else{
+    sqlite3_result_error_code(pCtx, rc);
+  }
+  fts5BufferFree(&s);
+}
+
+/*
+** The implementation of user-defined scalar function fts5_rowid().
+*/
+static void fts5RowidFunction(
+  sqlite3_context *pCtx,          /* Function call context */
+  int nArg,                       /* Number of args (always 2) */
+  sqlite3_value **apVal           /* Function arguments */
+){
+  const char *zArg;
+  if( nArg==0 ){
+    sqlite3_result_error(pCtx, "should be: fts5_rowid(subject, ....)", -1);
+  }else{
+    zArg = (const char*)sqlite3_value_text(apVal[0]);
+    if( 0==sqlite3_stricmp(zArg, "segment") ){
+      i64 iRowid;
+      int segid, pgno;
+      if( nArg!=3 ){
+        sqlite3_result_error(pCtx, 
+            "should be: fts5_rowid('segment', segid, pgno))", -1
+        );
+      }else{
+        segid = sqlite3_value_int(apVal[1]);
+        pgno = sqlite3_value_int(apVal[2]);
+        iRowid = FTS5_SEGMENT_ROWID(segid, pgno);
+        sqlite3_result_int64(pCtx, iRowid);
+      }
+    }else{
+      sqlite3_result_error(pCtx, 
+        "first arg to fts5_rowid() must be 'segment'" , -1
+      );
+    }
+  }
+}
+
+/*
+** This is called as part of registering the FTS5 module with database
+** connection db. It registers several user-defined scalar functions useful
+** with FTS5.
+**
+** If successful, SQLITE_OK is returned. If an error occurs, some other
+** SQLite error code is returned instead.
+*/
+static int sqlite3Fts5IndexInit(sqlite3 *db){
+  int rc = sqlite3_create_function(
+      db, "fts5_decode", 2, SQLITE_UTF8, 0, fts5DecodeFunction, 0, 0
+  );
+
+  if( rc==SQLITE_OK ){
+    rc = sqlite3_create_function(
+        db, "fts5_decode_none", 2, 
+        SQLITE_UTF8, (void*)db, fts5DecodeFunction, 0, 0
+    );
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = sqlite3_create_function(
+        db, "fts5_rowid", -1, SQLITE_UTF8, 0, fts5RowidFunction, 0, 0
+    );
+  }
+  return rc;
+}
+
+
+static int sqlite3Fts5IndexReset(Fts5Index *p){
+  assert( p->pStruct==0 || p->iStructVersion!=0 );
+  if( fts5IndexDataVersion(p)!=p->iStructVersion ){
+    fts5StructureInvalidate(p);
+  }
+  return fts5IndexReturn(p);
+}
+
+/*
+** 2014 Jun 09
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This is an SQLite module implementing full-text search.
+*/
+
+
+/* #include "fts5Int.h" */
+
+/*
+** This variable is set to false when running tests for which the on disk
+** structures should not be corrupt. Otherwise, true. If it is false, extra
+** assert() conditions in the fts5 code are activated - conditions that are
+** only true if it is guaranteed that the fts5 database is not corrupt.
+*/
+SQLITE_API int sqlite3_fts5_may_be_corrupt = 1;
+
+
+typedef struct Fts5Auxdata Fts5Auxdata;
+typedef struct Fts5Auxiliary Fts5Auxiliary;
+typedef struct Fts5Cursor Fts5Cursor;
+typedef struct Fts5Sorter Fts5Sorter;
+typedef struct Fts5Table Fts5Table;
+typedef struct Fts5TokenizerModule Fts5TokenizerModule;
+
+/*
+** NOTES ON TRANSACTIONS: 
+**
+** SQLite invokes the following virtual table methods as transactions are 
+** opened and closed by the user:
+**
+**     xBegin():    Start of a new transaction.
+**     xSync():     Initial part of two-phase commit.
+**     xCommit():   Final part of two-phase commit.
+**     xRollback(): Rollback the transaction.
+**
+** Anything that is required as part of a commit that may fail is performed
+** in the xSync() callback. Current versions of SQLite ignore any errors 
+** returned by xCommit().
+**
+** And as sub-transactions are opened/closed:
+**
+**     xSavepoint(int S):  Open savepoint S.
+**     xRelease(int S):    Commit and close savepoint S.
+**     xRollbackTo(int S): Rollback to start of savepoint S.
+**
+** During a write-transaction the fts5_index.c module may cache some data 
+** in-memory. It is flushed to disk whenever xSync(), xRelease() or
+** xSavepoint() is called. And discarded whenever xRollback() or xRollbackTo() 
+** is called.
+**
+** Additionally, if SQLITE_DEBUG is defined, an instance of the following
+** structure is used to record the current transaction state. This information
+** is not required, but it is used in the assert() statements executed by
+** function fts5CheckTransactionState() (see below).
+*/
+struct Fts5TransactionState {
+  int eState;                     /* 0==closed, 1==open, 2==synced */
+  int iSavepoint;                 /* Number of open savepoints (0 -> none) */
+};
+
+/*
+** A single object of this type is allocated when the FTS5 module is 
+** registered with a database handle. It is used to store pointers to
+** all registered FTS5 extensions - tokenizers and auxiliary functions.
+*/
+struct Fts5Global {
+  fts5_api api;                   /* User visible part of object (see fts5.h) */
+  sqlite3 *db;                    /* Associated database connection */ 
+  i64 iNextId;                    /* Used to allocate unique cursor ids */
+  Fts5Auxiliary *pAux;            /* First in list of all aux. functions */
+  Fts5TokenizerModule *pTok;      /* First in list of all tokenizer modules */
+  Fts5TokenizerModule *pDfltTok;  /* Default tokenizer module */
+  Fts5Cursor *pCsr;               /* First in list of all open cursors */
+};
+
+/*
+** Each auxiliary function registered with the FTS5 module is represented
+** by an object of the following type. All such objects are stored as part
+** of the Fts5Global.pAux list.
+*/
+struct Fts5Auxiliary {
+  Fts5Global *pGlobal;            /* Global context for this function */
+  char *zFunc;                    /* Function name (nul-terminated) */
+  void *pUserData;                /* User-data pointer */
+  fts5_extension_function xFunc;  /* Callback function */
+  void (*xDestroy)(void*);        /* Destructor function */
+  Fts5Auxiliary *pNext;           /* Next registered auxiliary function */
+};
+
+/*
+** Each tokenizer module registered with the FTS5 module is represented
+** by an object of the following type. All such objects are stored as part
+** of the Fts5Global.pTok list.
+*/
+struct Fts5TokenizerModule {
+  char *zName;                    /* Name of tokenizer */
+  void *pUserData;                /* User pointer passed to xCreate() */
+  fts5_tokenizer x;               /* Tokenizer functions */
+  void (*xDestroy)(void*);        /* Destructor function */
+  Fts5TokenizerModule *pNext;     /* Next registered tokenizer module */
+};
+
+/*
+** Virtual-table object.
+*/
+struct Fts5Table {
+  sqlite3_vtab base;              /* Base class used by SQLite core */
+  Fts5Config *pConfig;            /* Virtual table configuration */
+  Fts5Index *pIndex;              /* Full-text index */
+  Fts5Storage *pStorage;          /* Document store */
+  Fts5Global *pGlobal;            /* Global (connection wide) data */
+  Fts5Cursor *pSortCsr;           /* Sort data from this cursor */
+#ifdef SQLITE_DEBUG
+  struct Fts5TransactionState ts;
+#endif
+};
+
+struct Fts5MatchPhrase {
+  Fts5Buffer *pPoslist;           /* Pointer to current poslist */
+  int nTerm;                      /* Size of phrase in terms */
+};
+
+/*
+** pStmt:
+**   SELECT rowid, <fts> FROM <fts> ORDER BY +rank;
+**
+** aIdx[]:
+**   There is one entry in the aIdx[] array for each phrase in the query,
+**   the value of which is the offset within aPoslist[] following the last 
+**   byte of the position list for the corresponding phrase.
+*/
+struct Fts5Sorter {
+  sqlite3_stmt *pStmt;
+  i64 iRowid;                     /* Current rowid */
+  const u8 *aPoslist;             /* Position lists for current row */
+  int nIdx;                       /* Number of entries in aIdx[] */
+  int aIdx[1];                    /* Offsets into aPoslist for current row */
+};
+
+
+/*
+** Virtual-table cursor object.
+**
+** iSpecial:
+**   If this is a 'special' query (refer to function fts5SpecialMatch()), 
+**   then this variable contains the result of the query. 
+**
+** iFirstRowid, iLastRowid:
+**   These variables are only used for FTS5_PLAN_MATCH cursors. Assuming the
+**   cursor iterates in ascending order of rowids, iFirstRowid is the lower
+**   limit of rowids to return, and iLastRowid the upper. In other words, the
+**   WHERE clause in the user's query might have been:
+**
+**       <tbl> MATCH <expr> AND rowid BETWEEN $iFirstRowid AND $iLastRowid
+**
+**   If the cursor iterates in descending order of rowid, iFirstRowid
+**   is the upper limit (i.e. the "first" rowid visited) and iLastRowid
+**   the lower.
+*/
+struct Fts5Cursor {
+  sqlite3_vtab_cursor base;       /* Base class used by SQLite core */
+  Fts5Cursor *pNext;              /* Next cursor in Fts5Cursor.pCsr list */
+  int *aColumnSize;               /* Values for xColumnSize() */
+  i64 iCsrId;                     /* Cursor id */
+
+  /* Zero from this point onwards on cursor reset */
+  int ePlan;                      /* FTS5_PLAN_XXX value */
+  int bDesc;                      /* True for "ORDER BY rowid DESC" queries */
+  i64 iFirstRowid;                /* Return no rowids earlier than this */
+  i64 iLastRowid;                 /* Return no rowids later than this */
+  sqlite3_stmt *pStmt;            /* Statement used to read %_content */
+  Fts5Expr *pExpr;                /* Expression for MATCH queries */
+  Fts5Sorter *pSorter;            /* Sorter for "ORDER BY rank" queries */
+  int csrflags;                   /* Mask of cursor flags (see below) */
+  i64 iSpecial;                   /* Result of special query */
+
+  /* "rank" function. Populated on demand from vtab.xColumn(). */
+  char *zRank;                    /* Custom rank function */
+  char *zRankArgs;                /* Custom rank function args */
+  Fts5Auxiliary *pRank;           /* Rank callback (or NULL) */
+  int nRankArg;                   /* Number of trailing arguments for rank() */
+  sqlite3_value **apRankArg;      /* Array of trailing arguments */
+  sqlite3_stmt *pRankArgStmt;     /* Origin of objects in apRankArg[] */
+
+  /* Auxiliary data storage */
+  Fts5Auxiliary *pAux;            /* Currently executing extension function */
+  Fts5Auxdata *pAuxdata;          /* First in linked list of saved aux-data */
+
+  /* Cache used by auxiliary functions xInst() and xInstCount() */
+  Fts5PoslistReader *aInstIter;   /* One for each phrase */
+  int nInstAlloc;                 /* Size of aInst[] array (entries / 3) */
+  int nInstCount;                 /* Number of phrase instances */
+  int *aInst;                     /* 3 integers per phrase instance */
+};
+
+/*
+** Bits that make up the "idxNum" parameter passed indirectly by 
+** xBestIndex() to xFilter().
+*/
+#define FTS5_BI_MATCH        0x0001         /* <tbl> MATCH ? */
+#define FTS5_BI_RANK         0x0002         /* rank MATCH ? */
+#define FTS5_BI_ROWID_EQ     0x0004         /* rowid == ? */
+#define FTS5_BI_ROWID_LE     0x0008         /* rowid <= ? */
+#define FTS5_BI_ROWID_GE     0x0010         /* rowid >= ? */
+
+#define FTS5_BI_ORDER_RANK   0x0020
+#define FTS5_BI_ORDER_ROWID  0x0040
+#define FTS5_BI_ORDER_DESC   0x0080
+
+/*
+** Values for Fts5Cursor.csrflags
+*/
+#define FTS5CSR_EOF               0x01
+#define FTS5CSR_REQUIRE_CONTENT   0x02
+#define FTS5CSR_REQUIRE_DOCSIZE   0x04
+#define FTS5CSR_REQUIRE_INST      0x08
+#define FTS5CSR_FREE_ZRANK        0x10
+#define FTS5CSR_REQUIRE_RESEEK    0x20
+#define FTS5CSR_REQUIRE_POSLIST   0x40
+
+#define BitFlagAllTest(x,y) (((x) & (y))==(y))
+#define BitFlagTest(x,y)    (((x) & (y))!=0)
+
+
+/*
+** Macros to Set(), Clear() and Test() cursor flags.
+*/
+#define CsrFlagSet(pCsr, flag)   ((pCsr)->csrflags |= (flag))
+#define CsrFlagClear(pCsr, flag) ((pCsr)->csrflags &= ~(flag))
+#define CsrFlagTest(pCsr, flag)  ((pCsr)->csrflags & (flag))
+
+struct Fts5Auxdata {
+  Fts5Auxiliary *pAux;            /* Extension to which this belongs */
+  void *pPtr;                     /* Pointer value */
+  void(*xDelete)(void*);          /* Destructor */
+  Fts5Auxdata *pNext;             /* Next object in linked list */
+};
+
+#ifdef SQLITE_DEBUG
+#define FTS5_BEGIN      1
+#define FTS5_SYNC       2
+#define FTS5_COMMIT     3
+#define FTS5_ROLLBACK   4
+#define FTS5_SAVEPOINT  5
+#define FTS5_RELEASE    6
+#define FTS5_ROLLBACKTO 7
+static void fts5CheckTransactionState(Fts5Table *p, int op, int iSavepoint){
+  switch( op ){
+    case FTS5_BEGIN:
+      assert( p->ts.eState==0 );
+      p->ts.eState = 1;
+      p->ts.iSavepoint = -1;
+      break;
+
+    case FTS5_SYNC:
+      assert( p->ts.eState==1 );
+      p->ts.eState = 2;
+      break;
+
+    case FTS5_COMMIT:
+      assert( p->ts.eState==2 );
+      p->ts.eState = 0;
+      break;
+
+    case FTS5_ROLLBACK:
+      assert( p->ts.eState==1 || p->ts.eState==2 || p->ts.eState==0 );
+      p->ts.eState = 0;
+      break;
+
+    case FTS5_SAVEPOINT:
+      assert( p->ts.eState==1 );
+      assert( iSavepoint>=0 );
+      assert( iSavepoint>p->ts.iSavepoint );
+      p->ts.iSavepoint = iSavepoint;
+      break;
+      
+    case FTS5_RELEASE:
+      assert( p->ts.eState==1 );
+      assert( iSavepoint>=0 );
+      assert( iSavepoint<=p->ts.iSavepoint );
+      p->ts.iSavepoint = iSavepoint-1;
+      break;
+
+    case FTS5_ROLLBACKTO:
+      assert( p->ts.eState==1 );
+      assert( iSavepoint>=0 );
+      assert( iSavepoint<=p->ts.iSavepoint );
+      p->ts.iSavepoint = iSavepoint;
+      break;
+  }
+}
+#else
+# define fts5CheckTransactionState(x,y,z)
+#endif
+
+/*
+** Return true if pTab is a contentless table.
+*/
+static int fts5IsContentless(Fts5Table *pTab){
+  return pTab->pConfig->eContent==FTS5_CONTENT_NONE;
+}
+
+/*
+** Delete a virtual table handle allocated by fts5InitVtab(). 
+*/
+static void fts5FreeVtab(Fts5Table *pTab){
+  if( pTab ){
+    sqlite3Fts5IndexClose(pTab->pIndex);
+    sqlite3Fts5StorageClose(pTab->pStorage);
+    sqlite3Fts5ConfigFree(pTab->pConfig);
+    sqlite3_free(pTab);
+  }
+}
+
+/*
+** The xDisconnect() virtual table method.
+*/
+static int fts5DisconnectMethod(sqlite3_vtab *pVtab){
+  fts5FreeVtab((Fts5Table*)pVtab);
+  return SQLITE_OK;
+}
+
+/*
+** The xDestroy() virtual table method.
+*/
+static int fts5DestroyMethod(sqlite3_vtab *pVtab){
+  Fts5Table *pTab = (Fts5Table*)pVtab;
+  int rc = sqlite3Fts5DropAll(pTab->pConfig);
+  if( rc==SQLITE_OK ){
+    fts5FreeVtab((Fts5Table*)pVtab);
+  }
+  return rc;
+}
+
+/*
+** This function is the implementation of both the xConnect and xCreate
+** methods of the FTS3 virtual table.
+**
+** The argv[] array contains the following:
+**
+**   argv[0]   -> module name  ("fts5")
+**   argv[1]   -> database name
+**   argv[2]   -> table name
+**   argv[...] -> "column name" and other module argument fields.
+*/
+static int fts5InitVtab(
+  int bCreate,                    /* True for xCreate, false for xConnect */
+  sqlite3 *db,                    /* The SQLite database connection */
+  void *pAux,                     /* Hash table containing tokenizers */
+  int argc,                       /* Number of elements in argv array */
+  const char * const *argv,       /* xCreate/xConnect argument array */
+  sqlite3_vtab **ppVTab,          /* Write the resulting vtab structure here */
+  char **pzErr                    /* Write any error message here */
+){
+  Fts5Global *pGlobal = (Fts5Global*)pAux;
+  const char **azConfig = (const char**)argv;
+  int rc = SQLITE_OK;             /* Return code */
+  Fts5Config *pConfig = 0;        /* Results of parsing argc/argv */
+  Fts5Table *pTab = 0;            /* New virtual table object */
+
+  /* Allocate the new vtab object and parse the configuration */
+  pTab = (Fts5Table*)sqlite3Fts5MallocZero(&rc, sizeof(Fts5Table));
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts5ConfigParse(pGlobal, db, argc, azConfig, &pConfig, pzErr);
+    assert( (rc==SQLITE_OK && *pzErr==0) || pConfig==0 );
+  }
+  if( rc==SQLITE_OK ){
+    pTab->pConfig = pConfig;
+    pTab->pGlobal = pGlobal;
+  }
+
+  /* Open the index sub-system */
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts5IndexOpen(pConfig, bCreate, &pTab->pIndex, pzErr);
+  }
+
+  /* Open the storage sub-system */
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts5StorageOpen(
+        pConfig, pTab->pIndex, bCreate, &pTab->pStorage, pzErr
+    );
+  }
+
+  /* Call sqlite3_declare_vtab() */
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts5ConfigDeclareVtab(pConfig);
+  }
+
+  /* Load the initial configuration */
+  if( rc==SQLITE_OK ){
+    assert( pConfig->pzErrmsg==0 );
+    pConfig->pzErrmsg = pzErr;
+    rc = sqlite3Fts5IndexLoadConfig(pTab->pIndex);
+    sqlite3Fts5IndexRollback(pTab->pIndex);
+    pConfig->pzErrmsg = 0;
+  }
+
+  if( rc!=SQLITE_OK ){
+    fts5FreeVtab(pTab);
+    pTab = 0;
+  }else if( bCreate ){
+    fts5CheckTransactionState(pTab, FTS5_BEGIN, 0);
+  }
+  *ppVTab = (sqlite3_vtab*)pTab;
+  return rc;
+}
+
+/*
+** The xConnect() and xCreate() methods for the virtual table. All the
+** work is done in function fts5InitVtab().
+*/
+static int fts5ConnectMethod(
+  sqlite3 *db,                    /* Database connection */
+  void *pAux,                     /* Pointer to tokenizer hash table */
+  int argc,                       /* Number of elements in argv array */
+  const char * const *argv,       /* xCreate/xConnect argument array */
+  sqlite3_vtab **ppVtab,          /* OUT: New sqlite3_vtab object */
+  char **pzErr                    /* OUT: sqlite3_malloc'd error message */
+){
+  return fts5InitVtab(0, db, pAux, argc, argv, ppVtab, pzErr);
+}
+static int fts5CreateMethod(
+  sqlite3 *db,                    /* Database connection */
+  void *pAux,                     /* Pointer to tokenizer hash table */
+  int argc,                       /* Number of elements in argv array */
+  const char * const *argv,       /* xCreate/xConnect argument array */
+  sqlite3_vtab **ppVtab,          /* OUT: New sqlite3_vtab object */
+  char **pzErr                    /* OUT: sqlite3_malloc'd error message */
+){
+  return fts5InitVtab(1, db, pAux, argc, argv, ppVtab, pzErr);
+}
+
+/*
+** The different query plans.
+*/
+#define FTS5_PLAN_MATCH          1       /* (<tbl> MATCH ?) */
+#define FTS5_PLAN_SOURCE         2       /* A source cursor for SORTED_MATCH */
+#define FTS5_PLAN_SPECIAL        3       /* An internal query */
+#define FTS5_PLAN_SORTED_MATCH   4       /* (<tbl> MATCH ? ORDER BY rank) */
+#define FTS5_PLAN_SCAN           5       /* No usable constraint */
+#define FTS5_PLAN_ROWID          6       /* (rowid = ?) */
+
+/*
+** Set the SQLITE_INDEX_SCAN_UNIQUE flag in pIdxInfo->flags. Unless this
+** extension is currently being used by a version of SQLite too old to
+** support index-info flags. In that case this function is a no-op.
+*/
+static void fts5SetUniqueFlag(sqlite3_index_info *pIdxInfo){
+#if SQLITE_VERSION_NUMBER>=3008012
+#ifndef SQLITE_CORE
+  if( sqlite3_libversion_number()>=3008012 )
+#endif
+  {
+    pIdxInfo->idxFlags |= SQLITE_INDEX_SCAN_UNIQUE;
+  }
+#endif
+}
+
+/*
+** Implementation of the xBestIndex method for FTS5 tables. Within the 
+** WHERE constraint, it searches for the following:
+**
+**   1. A MATCH constraint against the special column.
+**   2. A MATCH constraint against the "rank" column.
+**   3. An == constraint against the rowid column.
+**   4. A < or <= constraint against the rowid column.
+**   5. A > or >= constraint against the rowid column.
+**
+** Within the ORDER BY, either:
+**
+**   5. ORDER BY rank [ASC|DESC]
+**   6. ORDER BY rowid [ASC|DESC]
+**
+** Costs are assigned as follows:
+**
+**  a) If an unusable MATCH operator is present in the WHERE clause, the
+**     cost is unconditionally set to 1e50 (a really big number).
+**
+**  a) If a MATCH operator is present, the cost depends on the other
+**     constraints also present. As follows:
+**
+**       * No other constraints:         cost=1000.0
+**       * One rowid range constraint:   cost=750.0
+**       * Both rowid range constraints: cost=500.0
+**       * An == rowid constraint:       cost=100.0
+**
+**  b) Otherwise, if there is no MATCH:
+**
+**       * No other constraints:         cost=1000000.0
+**       * One rowid range constraint:   cost=750000.0
+**       * Both rowid range constraints: cost=250000.0
+**       * An == rowid constraint:       cost=10.0
+**
+** Costs are not modified by the ORDER BY clause.
+*/
+static int fts5BestIndexMethod(sqlite3_vtab *pVTab, sqlite3_index_info *pInfo){
+  Fts5Table *pTab = (Fts5Table*)pVTab;
+  Fts5Config *pConfig = pTab->pConfig;
+  int idxFlags = 0;               /* Parameter passed through to xFilter() */
+  int bHasMatch;
+  int iNext;
+  int i;
+
+  struct Constraint {
+    int op;                       /* Mask against sqlite3_index_constraint.op */
+    int fts5op;                   /* FTS5 mask for idxFlags */
+    int iCol;                     /* 0==rowid, 1==tbl, 2==rank */
+    int omit;                     /* True to omit this if found */
+    int iConsIndex;               /* Index in pInfo->aConstraint[] */
+  } aConstraint[] = {
+    {SQLITE_INDEX_CONSTRAINT_MATCH|SQLITE_INDEX_CONSTRAINT_EQ, 
+                                    FTS5_BI_MATCH,    1, 1, -1},
+    {SQLITE_INDEX_CONSTRAINT_MATCH|SQLITE_INDEX_CONSTRAINT_EQ, 
+                                    FTS5_BI_RANK,     2, 1, -1},
+    {SQLITE_INDEX_CONSTRAINT_EQ,    FTS5_BI_ROWID_EQ, 0, 0, -1},
+    {SQLITE_INDEX_CONSTRAINT_LT|SQLITE_INDEX_CONSTRAINT_LE, 
+                                    FTS5_BI_ROWID_LE, 0, 0, -1},
+    {SQLITE_INDEX_CONSTRAINT_GT|SQLITE_INDEX_CONSTRAINT_GE, 
+                                    FTS5_BI_ROWID_GE, 0, 0, -1},
+  };
+
+  int aColMap[3];
+  aColMap[0] = -1;
+  aColMap[1] = pConfig->nCol;
+  aColMap[2] = pConfig->nCol+1;
+
+  /* Set idxFlags flags for all WHERE clause terms that will be used. */
+  for(i=0; i<pInfo->nConstraint; i++){
+    struct sqlite3_index_constraint *p = &pInfo->aConstraint[i];
+    int j;
+    for(j=0; j<ArraySize(aConstraint); j++){
+      struct Constraint *pC = &aConstraint[j];
+      if( p->iColumn==aColMap[pC->iCol] && p->op & pC->op ){
+        if( p->usable ){
+          pC->iConsIndex = i;
+          idxFlags |= pC->fts5op;
+        }else if( j==0 ){
+          /* As there exists an unusable MATCH constraint this is an 
+          ** unusable plan. Set a prohibitively high cost. */
+          pInfo->estimatedCost = 1e50;
+          return SQLITE_OK;
+        }
+      }
+    }
+  }
+
+  /* Set idxFlags flags for the ORDER BY clause */
+  if( pInfo->nOrderBy==1 ){
+    int iSort = pInfo->aOrderBy[0].iColumn;
+    if( iSort==(pConfig->nCol+1) && BitFlagTest(idxFlags, FTS5_BI_MATCH) ){
+      idxFlags |= FTS5_BI_ORDER_RANK;
+    }else if( iSort==-1 ){
+      idxFlags |= FTS5_BI_ORDER_ROWID;
+    }
+    if( BitFlagTest(idxFlags, FTS5_BI_ORDER_RANK|FTS5_BI_ORDER_ROWID) ){
+      pInfo->orderByConsumed = 1;
+      if( pInfo->aOrderBy[0].desc ){
+        idxFlags |= FTS5_BI_ORDER_DESC;
+      }
+    }
+  }
+
+  /* Calculate the estimated cost based on the flags set in idxFlags. */
+  bHasMatch = BitFlagTest(idxFlags, FTS5_BI_MATCH);
+  if( BitFlagTest(idxFlags, FTS5_BI_ROWID_EQ) ){
+    pInfo->estimatedCost = bHasMatch ? 100.0 : 10.0;
+    if( bHasMatch==0 ) fts5SetUniqueFlag(pInfo);
+  }else if( BitFlagAllTest(idxFlags, FTS5_BI_ROWID_LE|FTS5_BI_ROWID_GE) ){
+    pInfo->estimatedCost = bHasMatch ? 500.0 : 250000.0;
+  }else if( BitFlagTest(idxFlags, FTS5_BI_ROWID_LE|FTS5_BI_ROWID_GE) ){
+    pInfo->estimatedCost = bHasMatch ? 750.0 : 750000.0;
+  }else{
+    pInfo->estimatedCost = bHasMatch ? 1000.0 : 1000000.0;
+  }
+
+  /* Assign argvIndex values to each constraint in use. */
+  iNext = 1;
+  for(i=0; i<ArraySize(aConstraint); i++){
+    struct Constraint *pC = &aConstraint[i];
+    if( pC->iConsIndex>=0 ){
+      pInfo->aConstraintUsage[pC->iConsIndex].argvIndex = iNext++;
+      pInfo->aConstraintUsage[pC->iConsIndex].omit = (unsigned char)pC->omit;
+    }
+  }
+
+  pInfo->idxNum = idxFlags;
+  return SQLITE_OK;
+}
+
+static int fts5NewTransaction(Fts5Table *pTab){
+  Fts5Cursor *pCsr;
+  for(pCsr=pTab->pGlobal->pCsr; pCsr; pCsr=pCsr->pNext){
+    if( pCsr->base.pVtab==(sqlite3_vtab*)pTab ) return SQLITE_OK;
+  }
+  return sqlite3Fts5StorageReset(pTab->pStorage);
+}
+
+/*
+** Implementation of xOpen method.
+*/
+static int fts5OpenMethod(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCsr){
+  Fts5Table *pTab = (Fts5Table*)pVTab;
+  Fts5Config *pConfig = pTab->pConfig;
+  Fts5Cursor *pCsr = 0;           /* New cursor object */
+  int nByte;                      /* Bytes of space to allocate */
+  int rc;                         /* Return code */
+
+  rc = fts5NewTransaction(pTab);
+  if( rc==SQLITE_OK ){
+    nByte = sizeof(Fts5Cursor) + pConfig->nCol * sizeof(int);
+    pCsr = (Fts5Cursor*)sqlite3_malloc(nByte);
+    if( pCsr ){
+      Fts5Global *pGlobal = pTab->pGlobal;
+      memset(pCsr, 0, nByte);
+      pCsr->aColumnSize = (int*)&pCsr[1];
+      pCsr->pNext = pGlobal->pCsr;
+      pGlobal->pCsr = pCsr;
+      pCsr->iCsrId = ++pGlobal->iNextId;
+    }else{
+      rc = SQLITE_NOMEM;
+    }
+  }
+  *ppCsr = (sqlite3_vtab_cursor*)pCsr;
+  return rc;
+}
+
+static int fts5StmtType(Fts5Cursor *pCsr){
+  if( pCsr->ePlan==FTS5_PLAN_SCAN ){
+    return (pCsr->bDesc) ? FTS5_STMT_SCAN_DESC : FTS5_STMT_SCAN_ASC;
+  }
+  return FTS5_STMT_LOOKUP;
+}
+
+/*
+** This function is called after the cursor passed as the only argument
+** is moved to point at a different row. It clears all cached data 
+** specific to the previous row stored by the cursor object.
+*/
+static void fts5CsrNewrow(Fts5Cursor *pCsr){
+  CsrFlagSet(pCsr, 
+      FTS5CSR_REQUIRE_CONTENT 
+    | FTS5CSR_REQUIRE_DOCSIZE 
+    | FTS5CSR_REQUIRE_INST 
+    | FTS5CSR_REQUIRE_POSLIST 
+  );
+}
+
+static void fts5FreeCursorComponents(Fts5Cursor *pCsr){
+  Fts5Table *pTab = (Fts5Table*)(pCsr->base.pVtab);
+  Fts5Auxdata *pData;
+  Fts5Auxdata *pNext;
+
+  sqlite3_free(pCsr->aInstIter);
+  sqlite3_free(pCsr->aInst);
+  if( pCsr->pStmt ){
+    int eStmt = fts5StmtType(pCsr);
+    sqlite3Fts5StorageStmtRelease(pTab->pStorage, eStmt, pCsr->pStmt);
+  }
+  if( pCsr->pSorter ){
+    Fts5Sorter *pSorter = pCsr->pSorter;
+    sqlite3_finalize(pSorter->pStmt);
+    sqlite3_free(pSorter);
+  }
+
+  if( pCsr->ePlan!=FTS5_PLAN_SOURCE ){
+    sqlite3Fts5ExprFree(pCsr->pExpr);
+  }
+
+  for(pData=pCsr->pAuxdata; pData; pData=pNext){
+    pNext = pData->pNext;
+    if( pData->xDelete ) pData->xDelete(pData->pPtr);
+    sqlite3_free(pData);
+  }
+
+  sqlite3_finalize(pCsr->pRankArgStmt);
+  sqlite3_free(pCsr->apRankArg);
+
+  if( CsrFlagTest(pCsr, FTS5CSR_FREE_ZRANK) ){
+    sqlite3_free(pCsr->zRank);
+    sqlite3_free(pCsr->zRankArgs);
+  }
+
+  memset(&pCsr->ePlan, 0, sizeof(Fts5Cursor) - ((u8*)&pCsr->ePlan - (u8*)pCsr));
+}
+
+
+/*
+** Close the cursor.  For additional information see the documentation
+** on the xClose method of the virtual table interface.
+*/
+static int fts5CloseMethod(sqlite3_vtab_cursor *pCursor){
+  if( pCursor ){
+    Fts5Table *pTab = (Fts5Table*)(pCursor->pVtab);
+    Fts5Cursor *pCsr = (Fts5Cursor*)pCursor;
+    Fts5Cursor **pp;
+
+    fts5FreeCursorComponents(pCsr);
+    /* Remove the cursor from the Fts5Global.pCsr list */
+    for(pp=&pTab->pGlobal->pCsr; (*pp)!=pCsr; pp=&(*pp)->pNext);
+    *pp = pCsr->pNext;
+
+    sqlite3_free(pCsr);
+  }
+  return SQLITE_OK;
+}
+
+static int fts5SorterNext(Fts5Cursor *pCsr){
+  Fts5Sorter *pSorter = pCsr->pSorter;
+  int rc;
+
+  rc = sqlite3_step(pSorter->pStmt);
+  if( rc==SQLITE_DONE ){
+    rc = SQLITE_OK;
+    CsrFlagSet(pCsr, FTS5CSR_EOF);
+  }else if( rc==SQLITE_ROW ){
+    const u8 *a;
+    const u8 *aBlob;
+    int nBlob;
+    int i;
+    int iOff = 0;
+    rc = SQLITE_OK;
+
+    pSorter->iRowid = sqlite3_column_int64(pSorter->pStmt, 0);
+    nBlob = sqlite3_column_bytes(pSorter->pStmt, 1);
+    aBlob = a = sqlite3_column_blob(pSorter->pStmt, 1);
+
+    /* nBlob==0 in detail=none mode. */
+    if( nBlob>0 ){
+      for(i=0; i<(pSorter->nIdx-1); i++){
+        int iVal;
+        a += fts5GetVarint32(a, iVal);
+        iOff += iVal;
+        pSorter->aIdx[i] = iOff;
+      }
+      pSorter->aIdx[i] = &aBlob[nBlob] - a;
+      pSorter->aPoslist = a;
+    }
+
+    fts5CsrNewrow(pCsr);
+  }
+
+  return rc;
+}
+
+
+/*
+** Set the FTS5CSR_REQUIRE_RESEEK flag on all FTS5_PLAN_MATCH cursors 
+** open on table pTab.
+*/
+static void fts5TripCursors(Fts5Table *pTab){
+  Fts5Cursor *pCsr;
+  for(pCsr=pTab->pGlobal->pCsr; pCsr; pCsr=pCsr->pNext){
+    if( pCsr->ePlan==FTS5_PLAN_MATCH
+     && pCsr->base.pVtab==(sqlite3_vtab*)pTab 
+    ){
+      CsrFlagSet(pCsr, FTS5CSR_REQUIRE_RESEEK);
+    }
+  }
+}
+
+/*
+** If the REQUIRE_RESEEK flag is set on the cursor passed as the first
+** argument, close and reopen all Fts5IndexIter iterators that the cursor 
+** is using. Then attempt to move the cursor to a rowid equal to or laster
+** (in the cursors sort order - ASC or DESC) than the current rowid. 
+**
+** If the new rowid is not equal to the old, set output parameter *pbSkip
+** to 1 before returning. Otherwise, leave it unchanged.
+**
+** Return SQLITE_OK if successful or if no reseek was required, or an 
+** error code if an error occurred.
+*/
+static int fts5CursorReseek(Fts5Cursor *pCsr, int *pbSkip){
+  int rc = SQLITE_OK;
+  assert( *pbSkip==0 );
+  if( CsrFlagTest(pCsr, FTS5CSR_REQUIRE_RESEEK) ){
+    Fts5Table *pTab = (Fts5Table*)(pCsr->base.pVtab);
+    int bDesc = pCsr->bDesc;
+    i64 iRowid = sqlite3Fts5ExprRowid(pCsr->pExpr);
+
+    rc = sqlite3Fts5ExprFirst(pCsr->pExpr, pTab->pIndex, iRowid, bDesc);
+    if( rc==SQLITE_OK &&  iRowid!=sqlite3Fts5ExprRowid(pCsr->pExpr) ){
+      *pbSkip = 1;
+    }
+
+    CsrFlagClear(pCsr, FTS5CSR_REQUIRE_RESEEK);
+    fts5CsrNewrow(pCsr);
+    if( sqlite3Fts5ExprEof(pCsr->pExpr) ){
+      CsrFlagSet(pCsr, FTS5CSR_EOF);
+      *pbSkip = 1;
+    }
+  }
+  return rc;
+}
+
+
+/*
+** Advance the cursor to the next row in the table that matches the 
+** search criteria.
+**
+** Return SQLITE_OK if nothing goes wrong.  SQLITE_OK is returned
+** even if we reach end-of-file.  The fts5EofMethod() will be called
+** subsequently to determine whether or not an EOF was hit.
+*/
+static int fts5NextMethod(sqlite3_vtab_cursor *pCursor){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCursor;
+  int rc;
+
+  assert( (pCsr->ePlan<3)==
+          (pCsr->ePlan==FTS5_PLAN_MATCH || pCsr->ePlan==FTS5_PLAN_SOURCE) 
+  );
+  assert( !CsrFlagTest(pCsr, FTS5CSR_EOF) );
+
+  if( pCsr->ePlan<3 ){
+    int bSkip = 0;
+    if( (rc = fts5CursorReseek(pCsr, &bSkip)) || bSkip ) return rc;
+    rc = sqlite3Fts5ExprNext(pCsr->pExpr, pCsr->iLastRowid);
+    CsrFlagSet(pCsr, sqlite3Fts5ExprEof(pCsr->pExpr));
+    fts5CsrNewrow(pCsr);
+  }else{
+    switch( pCsr->ePlan ){
+      case FTS5_PLAN_SPECIAL: {
+        CsrFlagSet(pCsr, FTS5CSR_EOF);
+        rc = SQLITE_OK;
+        break;
+      }
+  
+      case FTS5_PLAN_SORTED_MATCH: {
+        rc = fts5SorterNext(pCsr);
+        break;
+      }
+  
+      default:
+        rc = sqlite3_step(pCsr->pStmt);
+        if( rc!=SQLITE_ROW ){
+          CsrFlagSet(pCsr, FTS5CSR_EOF);
+          rc = sqlite3_reset(pCsr->pStmt);
+        }else{
+          rc = SQLITE_OK;
+        }
+        break;
+    }
+  }
+  
+  return rc;
+}
+
+
+static int fts5PrepareStatement(
+  sqlite3_stmt **ppStmt,
+  Fts5Config *pConfig, 
+  const char *zFmt,
+  ...
+){
+  sqlite3_stmt *pRet = 0;
+  int rc;
+  char *zSql;
+  va_list ap;
+
+  va_start(ap, zFmt);
+  zSql = sqlite3_vmprintf(zFmt, ap);
+  if( zSql==0 ){
+    rc = SQLITE_NOMEM; 
+  }else{
+    rc = sqlite3_prepare_v2(pConfig->db, zSql, -1, &pRet, 0);
+    if( rc!=SQLITE_OK ){
+      *pConfig->pzErrmsg = sqlite3_mprintf("%s", sqlite3_errmsg(pConfig->db));
+    }
+    sqlite3_free(zSql);
+  }
+
+  va_end(ap);
+  *ppStmt = pRet;
+  return rc;
+} 
+
+static int fts5CursorFirstSorted(Fts5Table *pTab, Fts5Cursor *pCsr, int bDesc){
+  Fts5Config *pConfig = pTab->pConfig;
+  Fts5Sorter *pSorter;
+  int nPhrase;
+  int nByte;
+  int rc;
+  const char *zRank = pCsr->zRank;
+  const char *zRankArgs = pCsr->zRankArgs;
+  
+  nPhrase = sqlite3Fts5ExprPhraseCount(pCsr->pExpr);
+  nByte = sizeof(Fts5Sorter) + sizeof(int) * (nPhrase-1);
+  pSorter = (Fts5Sorter*)sqlite3_malloc(nByte);
+  if( pSorter==0 ) return SQLITE_NOMEM;
+  memset(pSorter, 0, nByte);
+  pSorter->nIdx = nPhrase;
+
+  /* TODO: It would be better to have some system for reusing statement
+  ** handles here, rather than preparing a new one for each query. But that
+  ** is not possible as SQLite reference counts the virtual table objects.
+  ** And since the statement required here reads from this very virtual 
+  ** table, saving it creates a circular reference.
+  **
+  ** If SQLite a built-in statement cache, this wouldn't be a problem. */
+  rc = fts5PrepareStatement(&pSorter->pStmt, pConfig,
+      "SELECT rowid, rank FROM %Q.%Q ORDER BY %s(%s%s%s) %s",
+      pConfig->zDb, pConfig->zName, zRank, pConfig->zName,
+      (zRankArgs ? ", " : ""),
+      (zRankArgs ? zRankArgs : ""),
+      bDesc ? "DESC" : "ASC"
+  );
+
+  pCsr->pSorter = pSorter;
+  if( rc==SQLITE_OK ){
+    assert( pTab->pSortCsr==0 );
+    pTab->pSortCsr = pCsr;
+    rc = fts5SorterNext(pCsr);
+    pTab->pSortCsr = 0;
+  }
+
+  if( rc!=SQLITE_OK ){
+    sqlite3_finalize(pSorter->pStmt);
+    sqlite3_free(pSorter);
+    pCsr->pSorter = 0;
+  }
+
+  return rc;
+}
+
+static int fts5CursorFirst(Fts5Table *pTab, Fts5Cursor *pCsr, int bDesc){
+  int rc;
+  Fts5Expr *pExpr = pCsr->pExpr;
+  rc = sqlite3Fts5ExprFirst(pExpr, pTab->pIndex, pCsr->iFirstRowid, bDesc);
+  if( sqlite3Fts5ExprEof(pExpr) ){
+    CsrFlagSet(pCsr, FTS5CSR_EOF);
+  }
+  fts5CsrNewrow(pCsr);
+  return rc;
+}
+
+/*
+** Process a "special" query. A special query is identified as one with a
+** MATCH expression that begins with a '*' character. The remainder of
+** the text passed to the MATCH operator are used as  the special query
+** parameters.
+*/
+static int fts5SpecialMatch(
+  Fts5Table *pTab, 
+  Fts5Cursor *pCsr, 
+  const char *zQuery
+){
+  int rc = SQLITE_OK;             /* Return code */
+  const char *z = zQuery;         /* Special query text */
+  int n;                          /* Number of bytes in text at z */
+
+  while( z[0]==' ' ) z++;
+  for(n=0; z[n] && z[n]!=' '; n++);
+
+  assert( pTab->base.zErrMsg==0 );
+  pCsr->ePlan = FTS5_PLAN_SPECIAL;
+
+  if( 0==sqlite3_strnicmp("reads", z, n) ){
+    pCsr->iSpecial = sqlite3Fts5IndexReads(pTab->pIndex);
+  }
+  else if( 0==sqlite3_strnicmp("id", z, n) ){
+    pCsr->iSpecial = pCsr->iCsrId;
+  }
+  else{
+    /* An unrecognized directive. Return an error message. */
+    pTab->base.zErrMsg = sqlite3_mprintf("unknown special query: %.*s", n, z);
+    rc = SQLITE_ERROR;
+  }
+
+  return rc;
+}
+
+/*
+** Search for an auxiliary function named zName that can be used with table
+** pTab. If one is found, return a pointer to the corresponding Fts5Auxiliary
+** structure. Otherwise, if no such function exists, return NULL.
+*/
+static Fts5Auxiliary *fts5FindAuxiliary(Fts5Table *pTab, const char *zName){
+  Fts5Auxiliary *pAux;
+
+  for(pAux=pTab->pGlobal->pAux; pAux; pAux=pAux->pNext){
+    if( sqlite3_stricmp(zName, pAux->zFunc)==0 ) return pAux;
+  }
+
+  /* No function of the specified name was found. Return 0. */
+  return 0;
+}
+
+
+static int fts5FindRankFunction(Fts5Cursor *pCsr){
+  Fts5Table *pTab = (Fts5Table*)(pCsr->base.pVtab);
+  Fts5Config *pConfig = pTab->pConfig;
+  int rc = SQLITE_OK;
+  Fts5Auxiliary *pAux = 0;
+  const char *zRank = pCsr->zRank;
+  const char *zRankArgs = pCsr->zRankArgs;
+
+  if( zRankArgs ){
+    char *zSql = sqlite3Fts5Mprintf(&rc, "SELECT %s", zRankArgs);
+    if( zSql ){
+      sqlite3_stmt *pStmt = 0;
+      rc = sqlite3_prepare_v2(pConfig->db, zSql, -1, &pStmt, 0);
+      sqlite3_free(zSql);
+      assert( rc==SQLITE_OK || pCsr->pRankArgStmt==0 );
+      if( rc==SQLITE_OK ){
+        if( SQLITE_ROW==sqlite3_step(pStmt) ){
+          int nByte;
+          pCsr->nRankArg = sqlite3_column_count(pStmt);
+          nByte = sizeof(sqlite3_value*)*pCsr->nRankArg;
+          pCsr->apRankArg = (sqlite3_value**)sqlite3Fts5MallocZero(&rc, nByte);
+          if( rc==SQLITE_OK ){
+            int i;
+            for(i=0; i<pCsr->nRankArg; i++){
+              pCsr->apRankArg[i] = sqlite3_column_value(pStmt, i);
+            }
+          }
+          pCsr->pRankArgStmt = pStmt;
+        }else{
+          rc = sqlite3_finalize(pStmt);
+          assert( rc!=SQLITE_OK );
+        }
+      }
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    pAux = fts5FindAuxiliary(pTab, zRank);
+    if( pAux==0 ){
+      assert( pTab->base.zErrMsg==0 );
+      pTab->base.zErrMsg = sqlite3_mprintf("no such function: %s", zRank);
+      rc = SQLITE_ERROR;
+    }
+  }
+
+  pCsr->pRank = pAux;
+  return rc;
+}
+
+
+static int fts5CursorParseRank(
+  Fts5Config *pConfig,
+  Fts5Cursor *pCsr, 
+  sqlite3_value *pRank
+){
+  int rc = SQLITE_OK;
+  if( pRank ){
+    const char *z = (const char*)sqlite3_value_text(pRank);
+    char *zRank = 0;
+    char *zRankArgs = 0;
+
+    if( z==0 ){
+      if( sqlite3_value_type(pRank)==SQLITE_NULL ) rc = SQLITE_ERROR;
+    }else{
+      rc = sqlite3Fts5ConfigParseRank(z, &zRank, &zRankArgs);
+    }
+    if( rc==SQLITE_OK ){
+      pCsr->zRank = zRank;
+      pCsr->zRankArgs = zRankArgs;
+      CsrFlagSet(pCsr, FTS5CSR_FREE_ZRANK);
+    }else if( rc==SQLITE_ERROR ){
+      pCsr->base.pVtab->zErrMsg = sqlite3_mprintf(
+          "parse error in rank function: %s", z
+      );
+    }
+  }else{
+    if( pConfig->zRank ){
+      pCsr->zRank = (char*)pConfig->zRank;
+      pCsr->zRankArgs = (char*)pConfig->zRankArgs;
+    }else{
+      pCsr->zRank = (char*)FTS5_DEFAULT_RANK;
+      pCsr->zRankArgs = 0;
+    }
+  }
+  return rc;
+}
+
+static i64 fts5GetRowidLimit(sqlite3_value *pVal, i64 iDefault){
+  if( pVal ){
+    int eType = sqlite3_value_numeric_type(pVal);
+    if( eType==SQLITE_INTEGER ){
+      return sqlite3_value_int64(pVal);
+    }
+  }
+  return iDefault;
+}
+
+/*
+** This is the xFilter interface for the virtual table.  See
+** the virtual table xFilter method documentation for additional
+** information.
+** 
+** There are three possible query strategies:
+**
+**   1. Full-text search using a MATCH operator.
+**   2. A by-rowid lookup.
+**   3. A full-table scan.
+*/
+static int fts5FilterMethod(
+  sqlite3_vtab_cursor *pCursor,   /* The cursor used for this query */
+  int idxNum,                     /* Strategy index */
+  const char *zUnused,            /* Unused */
+  int nVal,                       /* Number of elements in apVal */
+  sqlite3_value **apVal           /* Arguments for the indexing scheme */
+){
+  Fts5Table *pTab = (Fts5Table*)(pCursor->pVtab);
+  Fts5Config *pConfig = pTab->pConfig;
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCursor;
+  int rc = SQLITE_OK;             /* Error code */
+  int iVal = 0;                   /* Counter for apVal[] */
+  int bDesc;                      /* True if ORDER BY [rank|rowid] DESC */
+  int bOrderByRank;               /* True if ORDER BY rank */
+  sqlite3_value *pMatch = 0;      /* <tbl> MATCH ? expression (or NULL) */
+  sqlite3_value *pRank = 0;       /* rank MATCH ? expression (or NULL) */
+  sqlite3_value *pRowidEq = 0;    /* rowid = ? expression (or NULL) */
+  sqlite3_value *pRowidLe = 0;    /* rowid <= ? expression (or NULL) */
+  sqlite3_value *pRowidGe = 0;    /* rowid >= ? expression (or NULL) */
+  char **pzErrmsg = pConfig->pzErrmsg;
+
+  UNUSED_PARAM(zUnused);
+  UNUSED_PARAM(nVal);
+
+  if( pCsr->ePlan ){
+    fts5FreeCursorComponents(pCsr);
+    memset(&pCsr->ePlan, 0, sizeof(Fts5Cursor) - ((u8*)&pCsr->ePlan-(u8*)pCsr));
+  }
+
+  assert( pCsr->pStmt==0 );
+  assert( pCsr->pExpr==0 );
+  assert( pCsr->csrflags==0 );
+  assert( pCsr->pRank==0 );
+  assert( pCsr->zRank==0 );
+  assert( pCsr->zRankArgs==0 );
+
+  assert( pzErrmsg==0 || pzErrmsg==&pTab->base.zErrMsg );
+  pConfig->pzErrmsg = &pTab->base.zErrMsg;
+
+  /* Decode the arguments passed through to this function.
+  **
+  ** Note: The following set of if(...) statements must be in the same
+  ** order as the corresponding entries in the struct at the top of
+  ** fts5BestIndexMethod().  */
+  if( BitFlagTest(idxNum, FTS5_BI_MATCH) ) pMatch = apVal[iVal++];
+  if( BitFlagTest(idxNum, FTS5_BI_RANK) ) pRank = apVal[iVal++];
+  if( BitFlagTest(idxNum, FTS5_BI_ROWID_EQ) ) pRowidEq = apVal[iVal++];
+  if( BitFlagTest(idxNum, FTS5_BI_ROWID_LE) ) pRowidLe = apVal[iVal++];
+  if( BitFlagTest(idxNum, FTS5_BI_ROWID_GE) ) pRowidGe = apVal[iVal++];
+  assert( iVal==nVal );
+  bOrderByRank = ((idxNum & FTS5_BI_ORDER_RANK) ? 1 : 0);
+  pCsr->bDesc = bDesc = ((idxNum & FTS5_BI_ORDER_DESC) ? 1 : 0);
+
+  /* Set the cursor upper and lower rowid limits. Only some strategies 
+  ** actually use them. This is ok, as the xBestIndex() method leaves the
+  ** sqlite3_index_constraint.omit flag clear for range constraints
+  ** on the rowid field.  */
+  if( pRowidEq ){
+    pRowidLe = pRowidGe = pRowidEq;
+  }
+  if( bDesc ){
+    pCsr->iFirstRowid = fts5GetRowidLimit(pRowidLe, LARGEST_INT64);
+    pCsr->iLastRowid = fts5GetRowidLimit(pRowidGe, SMALLEST_INT64);
+  }else{
+    pCsr->iLastRowid = fts5GetRowidLimit(pRowidLe, LARGEST_INT64);
+    pCsr->iFirstRowid = fts5GetRowidLimit(pRowidGe, SMALLEST_INT64);
+  }
+
+  if( pTab->pSortCsr ){
+    /* If pSortCsr is non-NULL, then this call is being made as part of 
+    ** processing for a "... MATCH <expr> ORDER BY rank" query (ePlan is
+    ** set to FTS5_PLAN_SORTED_MATCH). pSortCsr is the cursor that will
+    ** return results to the user for this query. The current cursor 
+    ** (pCursor) is used to execute the query issued by function 
+    ** fts5CursorFirstSorted() above.  */
+    assert( pRowidEq==0 && pRowidLe==0 && pRowidGe==0 && pRank==0 );
+    assert( nVal==0 && pMatch==0 && bOrderByRank==0 && bDesc==0 );
+    assert( pCsr->iLastRowid==LARGEST_INT64 );
+    assert( pCsr->iFirstRowid==SMALLEST_INT64 );
+    pCsr->ePlan = FTS5_PLAN_SOURCE;
+    pCsr->pExpr = pTab->pSortCsr->pExpr;
+    rc = fts5CursorFirst(pTab, pCsr, bDesc);
+  }else if( pMatch ){
+    const char *zExpr = (const char*)sqlite3_value_text(apVal[0]);
+    if( zExpr==0 ) zExpr = "";
+
+    rc = fts5CursorParseRank(pConfig, pCsr, pRank);
+    if( rc==SQLITE_OK ){
+      if( zExpr[0]=='*' ){
+        /* The user has issued a query of the form "MATCH '*...'". This
+        ** indicates that the MATCH expression is not a full text query,
+        ** but a request for an internal parameter.  */
+        rc = fts5SpecialMatch(pTab, pCsr, &zExpr[1]);
+      }else{
+        char **pzErr = &pTab->base.zErrMsg;
+        rc = sqlite3Fts5ExprNew(pConfig, zExpr, &pCsr->pExpr, pzErr);
+        if( rc==SQLITE_OK ){
+          if( bOrderByRank ){
+            pCsr->ePlan = FTS5_PLAN_SORTED_MATCH;
+            rc = fts5CursorFirstSorted(pTab, pCsr, bDesc);
+          }else{
+            pCsr->ePlan = FTS5_PLAN_MATCH;
+            rc = fts5CursorFirst(pTab, pCsr, bDesc);
+          }
+        }
+      }
+    }
+  }else if( pConfig->zContent==0 ){
+    *pConfig->pzErrmsg = sqlite3_mprintf(
+        "%s: table does not support scanning", pConfig->zName
+    );
+    rc = SQLITE_ERROR;
+  }else{
+    /* This is either a full-table scan (ePlan==FTS5_PLAN_SCAN) or a lookup
+    ** by rowid (ePlan==FTS5_PLAN_ROWID).  */
+    pCsr->ePlan = (pRowidEq ? FTS5_PLAN_ROWID : FTS5_PLAN_SCAN);
+    rc = sqlite3Fts5StorageStmt(
+        pTab->pStorage, fts5StmtType(pCsr), &pCsr->pStmt, &pTab->base.zErrMsg
+    );
+    if( rc==SQLITE_OK ){
+      if( pCsr->ePlan==FTS5_PLAN_ROWID ){
+        sqlite3_bind_value(pCsr->pStmt, 1, apVal[0]);
+      }else{
+        sqlite3_bind_int64(pCsr->pStmt, 1, pCsr->iFirstRowid);
+        sqlite3_bind_int64(pCsr->pStmt, 2, pCsr->iLastRowid);
+      }
+      rc = fts5NextMethod(pCursor);
+    }
+  }
+
+  pConfig->pzErrmsg = pzErrmsg;
+  return rc;
+}
+
+/* 
+** This is the xEof method of the virtual table. SQLite calls this 
+** routine to find out if it has reached the end of a result set.
+*/
+static int fts5EofMethod(sqlite3_vtab_cursor *pCursor){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCursor;
+  return (CsrFlagTest(pCsr, FTS5CSR_EOF) ? 1 : 0);
+}
+
+/*
+** Return the rowid that the cursor currently points to.
+*/
+static i64 fts5CursorRowid(Fts5Cursor *pCsr){
+  assert( pCsr->ePlan==FTS5_PLAN_MATCH 
+       || pCsr->ePlan==FTS5_PLAN_SORTED_MATCH 
+       || pCsr->ePlan==FTS5_PLAN_SOURCE 
+  );
+  if( pCsr->pSorter ){
+    return pCsr->pSorter->iRowid;
+  }else{
+    return sqlite3Fts5ExprRowid(pCsr->pExpr);
+  }
+}
+
+/* 
+** This is the xRowid method. The SQLite core calls this routine to
+** retrieve the rowid for the current row of the result set. fts5
+** exposes %_content.rowid as the rowid for the virtual table. The
+** rowid should be written to *pRowid.
+*/
+static int fts5RowidMethod(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCursor;
+  int ePlan = pCsr->ePlan;
+  
+  assert( CsrFlagTest(pCsr, FTS5CSR_EOF)==0 );
+  switch( ePlan ){
+    case FTS5_PLAN_SPECIAL:
+      *pRowid = 0;
+      break;
+
+    case FTS5_PLAN_SOURCE:
+    case FTS5_PLAN_MATCH:
+    case FTS5_PLAN_SORTED_MATCH:
+      *pRowid = fts5CursorRowid(pCsr);
+      break;
+
+    default:
+      *pRowid = sqlite3_column_int64(pCsr->pStmt, 0);
+      break;
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** If the cursor requires seeking (bSeekRequired flag is set), seek it.
+** Return SQLITE_OK if no error occurs, or an SQLite error code otherwise.
+**
+** If argument bErrormsg is true and an error occurs, an error message may
+** be left in sqlite3_vtab.zErrMsg.
+*/
+static int fts5SeekCursor(Fts5Cursor *pCsr, int bErrormsg){
+  int rc = SQLITE_OK;
+
+  /* If the cursor does not yet have a statement handle, obtain one now. */ 
+  if( pCsr->pStmt==0 ){
+    Fts5Table *pTab = (Fts5Table*)(pCsr->base.pVtab);
+    int eStmt = fts5StmtType(pCsr);
+    rc = sqlite3Fts5StorageStmt(
+        pTab->pStorage, eStmt, &pCsr->pStmt, (bErrormsg?&pTab->base.zErrMsg:0)
+    );
+    assert( rc!=SQLITE_OK || pTab->base.zErrMsg==0 );
+    assert( CsrFlagTest(pCsr, FTS5CSR_REQUIRE_CONTENT) );
+  }
+
+  if( rc==SQLITE_OK && CsrFlagTest(pCsr, FTS5CSR_REQUIRE_CONTENT) ){
+    assert( pCsr->pExpr );
+    sqlite3_reset(pCsr->pStmt);
+    sqlite3_bind_int64(pCsr->pStmt, 1, fts5CursorRowid(pCsr));
+    rc = sqlite3_step(pCsr->pStmt);
+    if( rc==SQLITE_ROW ){
+      rc = SQLITE_OK;
+      CsrFlagClear(pCsr, FTS5CSR_REQUIRE_CONTENT);
+    }else{
+      rc = sqlite3_reset(pCsr->pStmt);
+      if( rc==SQLITE_OK ){
+        rc = FTS5_CORRUPT;
+      }
+    }
+  }
+  return rc;
+}
+
+static void fts5SetVtabError(Fts5Table *p, const char *zFormat, ...){
+  va_list ap;                     /* ... printf arguments */
+  va_start(ap, zFormat);
+  assert( p->base.zErrMsg==0 );
+  p->base.zErrMsg = sqlite3_vmprintf(zFormat, ap);
+  va_end(ap);
+}
+
+/*
+** This function is called to handle an FTS INSERT command. In other words,
+** an INSERT statement of the form:
+**
+**     INSERT INTO fts(fts) VALUES($pCmd)
+**     INSERT INTO fts(fts, rank) VALUES($pCmd, $pVal)
+**
+** Argument pVal is the value assigned to column "fts" by the INSERT 
+** statement. This function returns SQLITE_OK if successful, or an SQLite
+** error code if an error occurs.
+**
+** The commands implemented by this function are documented in the "Special
+** INSERT Directives" section of the documentation. It should be updated if
+** more commands are added to this function.
+*/
+static int fts5SpecialInsert(
+  Fts5Table *pTab,                /* Fts5 table object */
+  const char *zCmd,               /* Text inserted into table-name column */
+  sqlite3_value *pVal             /* Value inserted into rank column */
+){
+  Fts5Config *pConfig = pTab->pConfig;
+  int rc = SQLITE_OK;
+  int bError = 0;
+
+  if( 0==sqlite3_stricmp("delete-all", zCmd) ){
+    if( pConfig->eContent==FTS5_CONTENT_NORMAL ){
+      fts5SetVtabError(pTab, 
+          "'delete-all' may only be used with a "
+          "contentless or external content fts5 table"
+      );
+      rc = SQLITE_ERROR;
+    }else{
+      rc = sqlite3Fts5StorageDeleteAll(pTab->pStorage);
+    }
+  }else if( 0==sqlite3_stricmp("rebuild", zCmd) ){
+    if( pConfig->eContent==FTS5_CONTENT_NONE ){
+      fts5SetVtabError(pTab, 
+          "'rebuild' may not be used with a contentless fts5 table"
+      );
+      rc = SQLITE_ERROR;
+    }else{
+      rc = sqlite3Fts5StorageRebuild(pTab->pStorage);
+    }
+  }else if( 0==sqlite3_stricmp("optimize", zCmd) ){
+    rc = sqlite3Fts5StorageOptimize(pTab->pStorage);
+  }else if( 0==sqlite3_stricmp("merge", zCmd) ){
+    int nMerge = sqlite3_value_int(pVal);
+    rc = sqlite3Fts5StorageMerge(pTab->pStorage, nMerge);
+  }else if( 0==sqlite3_stricmp("integrity-check", zCmd) ){
+    rc = sqlite3Fts5StorageIntegrity(pTab->pStorage);
+#ifdef SQLITE_DEBUG
+  }else if( 0==sqlite3_stricmp("prefix-index", zCmd) ){
+    pConfig->bPrefixIndex = sqlite3_value_int(pVal);
+#endif
+  }else{
+    rc = sqlite3Fts5IndexLoadConfig(pTab->pIndex);
+    if( rc==SQLITE_OK ){
+      rc = sqlite3Fts5ConfigSetValue(pTab->pConfig, zCmd, pVal, &bError);
+    }
+    if( rc==SQLITE_OK ){
+      if( bError ){
+        rc = SQLITE_ERROR;
+      }else{
+        rc = sqlite3Fts5StorageConfigValue(pTab->pStorage, zCmd, pVal, 0);
+      }
+    }
+  }
+  return rc;
+}
+
+static int fts5SpecialDelete(
+  Fts5Table *pTab, 
+  sqlite3_value **apVal
+){
+  int rc = SQLITE_OK;
+  int eType1 = sqlite3_value_type(apVal[1]);
+  if( eType1==SQLITE_INTEGER ){
+    sqlite3_int64 iDel = sqlite3_value_int64(apVal[1]);
+    rc = sqlite3Fts5StorageDelete(pTab->pStorage, iDel, &apVal[2]);
+  }
+  return rc;
+}
+
+static void fts5StorageInsert(
+  int *pRc, 
+  Fts5Table *pTab, 
+  sqlite3_value **apVal, 
+  i64 *piRowid
+){
+  int rc = *pRc;
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts5StorageContentInsert(pTab->pStorage, apVal, piRowid);
+  }
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts5StorageIndexInsert(pTab->pStorage, apVal, *piRowid);
+  }
+  *pRc = rc;
+}
+
+/* 
+** This function is the implementation of the xUpdate callback used by 
+** FTS3 virtual tables. It is invoked by SQLite each time a row is to be
+** inserted, updated or deleted.
+**
+** A delete specifies a single argument - the rowid of the row to remove.
+** 
+** Update and insert operations pass:
+**
+**   1. The "old" rowid, or NULL.
+**   2. The "new" rowid.
+**   3. Values for each of the nCol matchable columns.
+**   4. Values for the two hidden columns (<tablename> and "rank").
+*/
+static int fts5UpdateMethod(
+  sqlite3_vtab *pVtab,            /* Virtual table handle */
+  int nArg,                       /* Size of argument array */
+  sqlite3_value **apVal,          /* Array of arguments */
+  sqlite_int64 *pRowid            /* OUT: The affected (or effected) rowid */
+){
+  Fts5Table *pTab = (Fts5Table*)pVtab;
+  Fts5Config *pConfig = pTab->pConfig;
+  int eType0;                     /* value_type() of apVal[0] */
+  int rc = SQLITE_OK;             /* Return code */
+
+  /* A transaction must be open when this is called. */
+  assert( pTab->ts.eState==1 );
+
+  assert( pVtab->zErrMsg==0 );
+  assert( nArg==1 || nArg==(2+pConfig->nCol+2) );
+  assert( nArg==1 
+      || sqlite3_value_type(apVal[1])==SQLITE_INTEGER 
+      || sqlite3_value_type(apVal[1])==SQLITE_NULL 
+  );
+  assert( pTab->pConfig->pzErrmsg==0 );
+  pTab->pConfig->pzErrmsg = &pTab->base.zErrMsg;
+
+  /* Put any active cursors into REQUIRE_SEEK state. */
+  fts5TripCursors(pTab);
+
+  eType0 = sqlite3_value_type(apVal[0]);
+  if( eType0==SQLITE_NULL 
+   && sqlite3_value_type(apVal[2+pConfig->nCol])!=SQLITE_NULL 
+  ){
+    /* A "special" INSERT op. These are handled separately. */
+    const char *z = (const char*)sqlite3_value_text(apVal[2+pConfig->nCol]);
+    if( pConfig->eContent!=FTS5_CONTENT_NORMAL 
+      && 0==sqlite3_stricmp("delete", z) 
+    ){
+      rc = fts5SpecialDelete(pTab, apVal);
+    }else{
+      rc = fts5SpecialInsert(pTab, z, apVal[2 + pConfig->nCol + 1]);
+    }
+  }else{
+    /* A regular INSERT, UPDATE or DELETE statement. The trick here is that
+    ** any conflict on the rowid value must be detected before any 
+    ** modifications are made to the database file. There are 4 cases:
+    **
+    **   1) DELETE
+    **   2) UPDATE (rowid not modified)
+    **   3) UPDATE (rowid modified)
+    **   4) INSERT
+    **
+    ** Cases 3 and 4 may violate the rowid constraint.
+    */
+    int eConflict = SQLITE_ABORT;
+    if( pConfig->eContent==FTS5_CONTENT_NORMAL ){
+      eConflict = sqlite3_vtab_on_conflict(pConfig->db);
+    }
+
+    assert( eType0==SQLITE_INTEGER || eType0==SQLITE_NULL );
+    assert( nArg!=1 || eType0==SQLITE_INTEGER );
+
+    /* Filter out attempts to run UPDATE or DELETE on contentless tables.
+    ** This is not suported.  */
+    if( eType0==SQLITE_INTEGER && fts5IsContentless(pTab) ){
+      pTab->base.zErrMsg = sqlite3_mprintf(
+          "cannot %s contentless fts5 table: %s", 
+          (nArg>1 ? "UPDATE" : "DELETE from"), pConfig->zName
+      );
+      rc = SQLITE_ERROR;
+    }
+
+    /* DELETE */
+    else if( nArg==1 ){
+      i64 iDel = sqlite3_value_int64(apVal[0]);  /* Rowid to delete */
+      rc = sqlite3Fts5StorageDelete(pTab->pStorage, iDel, 0);
+    }
+
+    /* INSERT */
+    else if( eType0!=SQLITE_INTEGER ){     
+      /* If this is a REPLACE, first remove the current entry (if any) */
+      if( eConflict==SQLITE_REPLACE 
+       && sqlite3_value_type(apVal[1])==SQLITE_INTEGER 
+      ){
+        i64 iNew = sqlite3_value_int64(apVal[1]);  /* Rowid to delete */
+        rc = sqlite3Fts5StorageDelete(pTab->pStorage, iNew, 0);
+      }
+      fts5StorageInsert(&rc, pTab, apVal, pRowid);
+    }
+
+    /* UPDATE */
+    else{
+      i64 iOld = sqlite3_value_int64(apVal[0]);  /* Old rowid */
+      i64 iNew = sqlite3_value_int64(apVal[1]);  /* New rowid */
+      if( iOld!=iNew ){
+        if( eConflict==SQLITE_REPLACE ){
+          rc = sqlite3Fts5StorageDelete(pTab->pStorage, iOld, 0);
+          if( rc==SQLITE_OK ){
+            rc = sqlite3Fts5StorageDelete(pTab->pStorage, iNew, 0);
+          }
+          fts5StorageInsert(&rc, pTab, apVal, pRowid);
+        }else{
+          rc = sqlite3Fts5StorageContentInsert(pTab->pStorage, apVal, pRowid);
+          if( rc==SQLITE_OK ){
+            rc = sqlite3Fts5StorageDelete(pTab->pStorage, iOld, 0);
+          }
+          if( rc==SQLITE_OK ){
+            rc = sqlite3Fts5StorageIndexInsert(pTab->pStorage, apVal, *pRowid);
+          }
+        }
+      }else{
+        rc = sqlite3Fts5StorageDelete(pTab->pStorage, iOld, 0);
+        fts5StorageInsert(&rc, pTab, apVal, pRowid);
+      }
+    }
+  }
+
+  pTab->pConfig->pzErrmsg = 0;
+  return rc;
+}
+
+/*
+** Implementation of xSync() method. 
+*/
+static int fts5SyncMethod(sqlite3_vtab *pVtab){
+  int rc;
+  Fts5Table *pTab = (Fts5Table*)pVtab;
+  fts5CheckTransactionState(pTab, FTS5_SYNC, 0);
+  pTab->pConfig->pzErrmsg = &pTab->base.zErrMsg;
+  fts5TripCursors(pTab);
+  rc = sqlite3Fts5StorageSync(pTab->pStorage, 1);
+  pTab->pConfig->pzErrmsg = 0;
+  return rc;
+}
+
+/*
+** Implementation of xBegin() method. 
+*/
+static int fts5BeginMethod(sqlite3_vtab *pVtab){
+  fts5CheckTransactionState((Fts5Table*)pVtab, FTS5_BEGIN, 0);
+  fts5NewTransaction((Fts5Table*)pVtab);
+  return SQLITE_OK;
+}
+
+/*
+** Implementation of xCommit() method. This is a no-op. The contents of
+** the pending-terms hash-table have already been flushed into the database
+** by fts5SyncMethod().
+*/
+static int fts5CommitMethod(sqlite3_vtab *pVtab){
+  UNUSED_PARAM(pVtab);  /* Call below is a no-op for NDEBUG builds */
+  fts5CheckTransactionState((Fts5Table*)pVtab, FTS5_COMMIT, 0);
+  return SQLITE_OK;
+}
+
+/*
+** Implementation of xRollback(). Discard the contents of the pending-terms
+** hash-table. Any changes made to the database are reverted by SQLite.
+*/
+static int fts5RollbackMethod(sqlite3_vtab *pVtab){
+  int rc;
+  Fts5Table *pTab = (Fts5Table*)pVtab;
+  fts5CheckTransactionState(pTab, FTS5_ROLLBACK, 0);
+  rc = sqlite3Fts5StorageRollback(pTab->pStorage);
+  return rc;
+}
+
+static int fts5CsrPoslist(Fts5Cursor*, int, const u8**, int*);
+
+static void *fts5ApiUserData(Fts5Context *pCtx){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  return pCsr->pAux->pUserData;
+}
+
+static int fts5ApiColumnCount(Fts5Context *pCtx){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  return ((Fts5Table*)(pCsr->base.pVtab))->pConfig->nCol;
+}
+
+static int fts5ApiColumnTotalSize(
+  Fts5Context *pCtx, 
+  int iCol, 
+  sqlite3_int64 *pnToken
+){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  Fts5Table *pTab = (Fts5Table*)(pCsr->base.pVtab);
+  return sqlite3Fts5StorageSize(pTab->pStorage, iCol, pnToken);
+}
+
+static int fts5ApiRowCount(Fts5Context *pCtx, i64 *pnRow){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  Fts5Table *pTab = (Fts5Table*)(pCsr->base.pVtab);
+  return sqlite3Fts5StorageRowCount(pTab->pStorage, pnRow);
+}
+
+static int fts5ApiTokenize(
+  Fts5Context *pCtx, 
+  const char *pText, int nText, 
+  void *pUserData,
+  int (*xToken)(void*, int, const char*, int, int, int)
+){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  Fts5Table *pTab = (Fts5Table*)(pCsr->base.pVtab);
+  return sqlite3Fts5Tokenize(
+      pTab->pConfig, FTS5_TOKENIZE_AUX, pText, nText, pUserData, xToken
+  );
+}
+
+static int fts5ApiPhraseCount(Fts5Context *pCtx){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  return sqlite3Fts5ExprPhraseCount(pCsr->pExpr);
+}
+
+static int fts5ApiPhraseSize(Fts5Context *pCtx, int iPhrase){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  return sqlite3Fts5ExprPhraseSize(pCsr->pExpr, iPhrase);
+}
+
+static int fts5ApiColumnText(
+  Fts5Context *pCtx, 
+  int iCol, 
+  const char **pz, 
+  int *pn
+){
+  int rc = SQLITE_OK;
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  if( fts5IsContentless((Fts5Table*)(pCsr->base.pVtab)) ){
+    *pz = 0;
+    *pn = 0;
+  }else{
+    rc = fts5SeekCursor(pCsr, 0);
+    if( rc==SQLITE_OK ){
+      *pz = (const char*)sqlite3_column_text(pCsr->pStmt, iCol+1);
+      *pn = sqlite3_column_bytes(pCsr->pStmt, iCol+1);
+    }
+  }
+  return rc;
+}
+
+static int fts5CsrPoslist(
+  Fts5Cursor *pCsr, 
+  int iPhrase, 
+  const u8 **pa,
+  int *pn
+){
+  Fts5Config *pConfig = ((Fts5Table*)(pCsr->base.pVtab))->pConfig;
+  int rc = SQLITE_OK;
+  int bLive = (pCsr->pSorter==0);
+
+  if( CsrFlagTest(pCsr, FTS5CSR_REQUIRE_POSLIST) ){
+
+    if( pConfig->eDetail!=FTS5_DETAIL_FULL ){
+      Fts5PoslistPopulator *aPopulator;
+      int i;
+      aPopulator = sqlite3Fts5ExprClearPoslists(pCsr->pExpr, bLive);
+      if( aPopulator==0 ) rc = SQLITE_NOMEM;
+      for(i=0; i<pConfig->nCol && rc==SQLITE_OK; i++){
+        int n; const char *z;
+        rc = fts5ApiColumnText((Fts5Context*)pCsr, i, &z, &n);
+        if( rc==SQLITE_OK ){
+          rc = sqlite3Fts5ExprPopulatePoslists(
+              pConfig, pCsr->pExpr, aPopulator, i, z, n
+          );
+        }
+      }
+      sqlite3_free(aPopulator);
+
+      if( pCsr->pSorter ){
+        sqlite3Fts5ExprCheckPoslists(pCsr->pExpr, pCsr->pSorter->iRowid);
+      }
+    }
+    CsrFlagClear(pCsr, FTS5CSR_REQUIRE_POSLIST);
+  }
+
+  if( pCsr->pSorter && pConfig->eDetail==FTS5_DETAIL_FULL ){
+    Fts5Sorter *pSorter = pCsr->pSorter;
+    int i1 = (iPhrase==0 ? 0 : pSorter->aIdx[iPhrase-1]);
+    *pn = pSorter->aIdx[iPhrase] - i1;
+    *pa = &pSorter->aPoslist[i1];
+  }else{
+    *pn = sqlite3Fts5ExprPoslist(pCsr->pExpr, iPhrase, pa);
+  }
+
+  return rc;
+}
+
+/*
+** Ensure that the Fts5Cursor.nInstCount and aInst[] variables are populated
+** correctly for the current view. Return SQLITE_OK if successful, or an
+** SQLite error code otherwise.
+*/
+static int fts5CacheInstArray(Fts5Cursor *pCsr){
+  int rc = SQLITE_OK;
+  Fts5PoslistReader *aIter;       /* One iterator for each phrase */
+  int nIter;                      /* Number of iterators/phrases */
+  
+  nIter = sqlite3Fts5ExprPhraseCount(pCsr->pExpr);
+  if( pCsr->aInstIter==0 ){
+    int nByte = sizeof(Fts5PoslistReader) * nIter;
+    pCsr->aInstIter = (Fts5PoslistReader*)sqlite3Fts5MallocZero(&rc, nByte);
+  }
+  aIter = pCsr->aInstIter;
+
+  if( aIter ){
+    int nInst = 0;                /* Number instances seen so far */
+    int i;
+
+    /* Initialize all iterators */
+    for(i=0; i<nIter && rc==SQLITE_OK; i++){
+      const u8 *a;
+      int n; 
+      rc = fts5CsrPoslist(pCsr, i, &a, &n);
+      if( rc==SQLITE_OK ){
+        sqlite3Fts5PoslistReaderInit(a, n, &aIter[i]);
+      }
+    }
+
+    if( rc==SQLITE_OK ){
+      while( 1 ){
+        int *aInst;
+        int iBest = -1;
+        for(i=0; i<nIter; i++){
+          if( (aIter[i].bEof==0) 
+              && (iBest<0 || aIter[i].iPos<aIter[iBest].iPos) 
+            ){
+            iBest = i;
+          }
+        }
+        if( iBest<0 ) break;
+
+        nInst++;
+        if( nInst>=pCsr->nInstAlloc ){
+          pCsr->nInstAlloc = pCsr->nInstAlloc ? pCsr->nInstAlloc*2 : 32;
+          aInst = (int*)sqlite3_realloc(
+              pCsr->aInst, pCsr->nInstAlloc*sizeof(int)*3
+              );
+          if( aInst ){
+            pCsr->aInst = aInst;
+          }else{
+            rc = SQLITE_NOMEM;
+            break;
+          }
+        }
+
+        aInst = &pCsr->aInst[3 * (nInst-1)];
+        aInst[0] = iBest;
+        aInst[1] = FTS5_POS2COLUMN(aIter[iBest].iPos);
+        aInst[2] = FTS5_POS2OFFSET(aIter[iBest].iPos);
+        sqlite3Fts5PoslistReaderNext(&aIter[iBest]);
+      }
+    }
+
+    pCsr->nInstCount = nInst;
+    CsrFlagClear(pCsr, FTS5CSR_REQUIRE_INST);
+  }
+  return rc;
+}
+
+static int fts5ApiInstCount(Fts5Context *pCtx, int *pnInst){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  int rc = SQLITE_OK;
+  if( CsrFlagTest(pCsr, FTS5CSR_REQUIRE_INST)==0 
+   || SQLITE_OK==(rc = fts5CacheInstArray(pCsr)) ){
+    *pnInst = pCsr->nInstCount;
+  }
+  return rc;
+}
+
+static int fts5ApiInst(
+  Fts5Context *pCtx, 
+  int iIdx, 
+  int *piPhrase, 
+  int *piCol, 
+  int *piOff
+){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  int rc = SQLITE_OK;
+  if( CsrFlagTest(pCsr, FTS5CSR_REQUIRE_INST)==0 
+   || SQLITE_OK==(rc = fts5CacheInstArray(pCsr)) 
+  ){
+    if( iIdx<0 || iIdx>=pCsr->nInstCount ){
+      rc = SQLITE_RANGE;
+#if 0
+    }else if( fts5IsOffsetless((Fts5Table*)pCsr->base.pVtab) ){
+      *piPhrase = pCsr->aInst[iIdx*3];
+      *piCol = pCsr->aInst[iIdx*3 + 2];
+      *piOff = -1;
+#endif
+    }else{
+      *piPhrase = pCsr->aInst[iIdx*3];
+      *piCol = pCsr->aInst[iIdx*3 + 1];
+      *piOff = pCsr->aInst[iIdx*3 + 2];
+    }
+  }
+  return rc;
+}
+
+static sqlite3_int64 fts5ApiRowid(Fts5Context *pCtx){
+  return fts5CursorRowid((Fts5Cursor*)pCtx);
+}
+
+static int fts5ColumnSizeCb(
+  void *pContext,                 /* Pointer to int */
+  int tflags,
+  const char *pUnused,            /* Buffer containing token */
+  int nUnused,                    /* Size of token in bytes */
+  int iUnused1,                   /* Start offset of token */
+  int iUnused2                    /* End offset of token */
+){
+  int *pCnt = (int*)pContext;
+  UNUSED_PARAM2(pUnused, nUnused);
+  UNUSED_PARAM2(iUnused1, iUnused2);
+  if( (tflags & FTS5_TOKEN_COLOCATED)==0 ){
+    (*pCnt)++;
+  }
+  return SQLITE_OK;
+}
+
+static int fts5ApiColumnSize(Fts5Context *pCtx, int iCol, int *pnToken){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  Fts5Table *pTab = (Fts5Table*)(pCsr->base.pVtab);
+  Fts5Config *pConfig = pTab->pConfig;
+  int rc = SQLITE_OK;
+
+  if( CsrFlagTest(pCsr, FTS5CSR_REQUIRE_DOCSIZE) ){
+    if( pConfig->bColumnsize ){
+      i64 iRowid = fts5CursorRowid(pCsr);
+      rc = sqlite3Fts5StorageDocsize(pTab->pStorage, iRowid, pCsr->aColumnSize);
+    }else if( pConfig->zContent==0 ){
+      int i;
+      for(i=0; i<pConfig->nCol; i++){
+        if( pConfig->abUnindexed[i]==0 ){
+          pCsr->aColumnSize[i] = -1;
+        }
+      }
+    }else{
+      int i;
+      for(i=0; rc==SQLITE_OK && i<pConfig->nCol; i++){
+        if( pConfig->abUnindexed[i]==0 ){
+          const char *z; int n;
+          void *p = (void*)(&pCsr->aColumnSize[i]);
+          pCsr->aColumnSize[i] = 0;
+          rc = fts5ApiColumnText(pCtx, i, &z, &n);
+          if( rc==SQLITE_OK ){
+            rc = sqlite3Fts5Tokenize(
+                pConfig, FTS5_TOKENIZE_AUX, z, n, p, fts5ColumnSizeCb
+            );
+          }
+        }
+      }
+    }
+    CsrFlagClear(pCsr, FTS5CSR_REQUIRE_DOCSIZE);
+  }
+  if( iCol<0 ){
+    int i;
+    *pnToken = 0;
+    for(i=0; i<pConfig->nCol; i++){
+      *pnToken += pCsr->aColumnSize[i];
+    }
+  }else if( iCol<pConfig->nCol ){
+    *pnToken = pCsr->aColumnSize[iCol];
+  }else{
+    *pnToken = 0;
+    rc = SQLITE_RANGE;
+  }
+  return rc;
+}
+
+/*
+** Implementation of the xSetAuxdata() method.
+*/
+static int fts5ApiSetAuxdata(
+  Fts5Context *pCtx,              /* Fts5 context */
+  void *pPtr,                     /* Pointer to save as auxdata */
+  void(*xDelete)(void*)           /* Destructor for pPtr (or NULL) */
+){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  Fts5Auxdata *pData;
+
+  /* Search through the cursors list of Fts5Auxdata objects for one that
+  ** corresponds to the currently executing auxiliary function.  */
+  for(pData=pCsr->pAuxdata; pData; pData=pData->pNext){
+    if( pData->pAux==pCsr->pAux ) break;
+  }
+
+  if( pData ){
+    if( pData->xDelete ){
+      pData->xDelete(pData->pPtr);
+    }
+  }else{
+    int rc = SQLITE_OK;
+    pData = (Fts5Auxdata*)sqlite3Fts5MallocZero(&rc, sizeof(Fts5Auxdata));
+    if( pData==0 ){
+      if( xDelete ) xDelete(pPtr);
+      return rc;
+    }
+    pData->pAux = pCsr->pAux;
+    pData->pNext = pCsr->pAuxdata;
+    pCsr->pAuxdata = pData;
+  }
+
+  pData->xDelete = xDelete;
+  pData->pPtr = pPtr;
+  return SQLITE_OK;
+}
+
+static void *fts5ApiGetAuxdata(Fts5Context *pCtx, int bClear){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  Fts5Auxdata *pData;
+  void *pRet = 0;
+
+  for(pData=pCsr->pAuxdata; pData; pData=pData->pNext){
+    if( pData->pAux==pCsr->pAux ) break;
+  }
+
+  if( pData ){
+    pRet = pData->pPtr;
+    if( bClear ){
+      pData->pPtr = 0;
+      pData->xDelete = 0;
+    }
+  }
+
+  return pRet;
+}
+
+static void fts5ApiPhraseNext(
+  Fts5Context *pUnused, 
+  Fts5PhraseIter *pIter, 
+  int *piCol, int *piOff
+){
+  UNUSED_PARAM(pUnused);
+  if( pIter->a>=pIter->b ){
+    *piCol = -1;
+    *piOff = -1;
+  }else{
+    int iVal;
+    pIter->a += fts5GetVarint32(pIter->a, iVal);
+    if( iVal==1 ){
+      pIter->a += fts5GetVarint32(pIter->a, iVal);
+      *piCol = iVal;
+      *piOff = 0;
+      pIter->a += fts5GetVarint32(pIter->a, iVal);
+    }
+    *piOff += (iVal-2);
+  }
+}
+
+static int fts5ApiPhraseFirst(
+  Fts5Context *pCtx, 
+  int iPhrase, 
+  Fts5PhraseIter *pIter, 
+  int *piCol, int *piOff
+){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  int n;
+  int rc = fts5CsrPoslist(pCsr, iPhrase, &pIter->a, &n);
+  if( rc==SQLITE_OK ){
+    pIter->b = &pIter->a[n];
+    *piCol = 0;
+    *piOff = 0;
+    fts5ApiPhraseNext(pCtx, pIter, piCol, piOff);
+  }
+  return rc;
+}
+
+static void fts5ApiPhraseNextColumn(
+  Fts5Context *pCtx, 
+  Fts5PhraseIter *pIter, 
+  int *piCol
+){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  Fts5Config *pConfig = ((Fts5Table*)(pCsr->base.pVtab))->pConfig;
+
+  if( pConfig->eDetail==FTS5_DETAIL_COLUMNS ){
+    if( pIter->a>=pIter->b ){
+      *piCol = -1;
+    }else{
+      int iIncr;
+      pIter->a += fts5GetVarint32(&pIter->a[0], iIncr);
+      *piCol += (iIncr-2);
+    }
+  }else{
+    while( 1 ){
+      int dummy;
+      if( pIter->a>=pIter->b ){
+        *piCol = -1;
+        return;
+      }
+      if( pIter->a[0]==0x01 ) break;
+      pIter->a += fts5GetVarint32(pIter->a, dummy);
+    }
+    pIter->a += 1 + fts5GetVarint32(&pIter->a[1], *piCol);
+  }
+}
+
+static int fts5ApiPhraseFirstColumn(
+  Fts5Context *pCtx, 
+  int iPhrase, 
+  Fts5PhraseIter *pIter, 
+  int *piCol
+){
+  int rc = SQLITE_OK;
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  Fts5Config *pConfig = ((Fts5Table*)(pCsr->base.pVtab))->pConfig;
+
+  if( pConfig->eDetail==FTS5_DETAIL_COLUMNS ){
+    Fts5Sorter *pSorter = pCsr->pSorter;
+    int n;
+    if( pSorter ){
+      int i1 = (iPhrase==0 ? 0 : pSorter->aIdx[iPhrase-1]);
+      n = pSorter->aIdx[iPhrase] - i1;
+      pIter->a = &pSorter->aPoslist[i1];
+    }else{
+      rc = sqlite3Fts5ExprPhraseCollist(pCsr->pExpr, iPhrase, &pIter->a, &n);
+    }
+    if( rc==SQLITE_OK ){
+      pIter->b = &pIter->a[n];
+      *piCol = 0;
+      fts5ApiPhraseNextColumn(pCtx, pIter, piCol);
+    }
+  }else{
+    int n;
+    rc = fts5CsrPoslist(pCsr, iPhrase, &pIter->a, &n);
+    if( rc==SQLITE_OK ){
+      pIter->b = &pIter->a[n];
+      if( n<=0 ){
+        *piCol = -1;
+      }else if( pIter->a[0]==0x01 ){
+        pIter->a += 1 + fts5GetVarint32(&pIter->a[1], *piCol);
+      }else{
+        *piCol = 0;
+      }
+    }
+  }
+
+  return rc;
+}
+
+
+static int fts5ApiQueryPhrase(Fts5Context*, int, void*, 
+    int(*)(const Fts5ExtensionApi*, Fts5Context*, void*)
+);
+
+static const Fts5ExtensionApi sFts5Api = {
+  2,                            /* iVersion */
+  fts5ApiUserData,
+  fts5ApiColumnCount,
+  fts5ApiRowCount,
+  fts5ApiColumnTotalSize,
+  fts5ApiTokenize,
+  fts5ApiPhraseCount,
+  fts5ApiPhraseSize,
+  fts5ApiInstCount,
+  fts5ApiInst,
+  fts5ApiRowid,
+  fts5ApiColumnText,
+  fts5ApiColumnSize,
+  fts5ApiQueryPhrase,
+  fts5ApiSetAuxdata,
+  fts5ApiGetAuxdata,
+  fts5ApiPhraseFirst,
+  fts5ApiPhraseNext,
+  fts5ApiPhraseFirstColumn,
+  fts5ApiPhraseNextColumn,
+};
+
+/*
+** Implementation of API function xQueryPhrase().
+*/
+static int fts5ApiQueryPhrase(
+  Fts5Context *pCtx, 
+  int iPhrase, 
+  void *pUserData,
+  int(*xCallback)(const Fts5ExtensionApi*, Fts5Context*, void*)
+){
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
+  Fts5Table *pTab = (Fts5Table*)(pCsr->base.pVtab);
+  int rc;
+  Fts5Cursor *pNew = 0;
+
+  rc = fts5OpenMethod(pCsr->base.pVtab, (sqlite3_vtab_cursor**)&pNew);
+  if( rc==SQLITE_OK ){
+    pNew->ePlan = FTS5_PLAN_MATCH;
+    pNew->iFirstRowid = SMALLEST_INT64;
+    pNew->iLastRowid = LARGEST_INT64;
+    pNew->base.pVtab = (sqlite3_vtab*)pTab;
+    rc = sqlite3Fts5ExprClonePhrase(pCsr->pExpr, iPhrase, &pNew->pExpr);
+  }
+
+  if( rc==SQLITE_OK ){
+    for(rc = fts5CursorFirst(pTab, pNew, 0);
+        rc==SQLITE_OK && CsrFlagTest(pNew, FTS5CSR_EOF)==0;
+        rc = fts5NextMethod((sqlite3_vtab_cursor*)pNew)
+    ){
+      rc = xCallback(&sFts5Api, (Fts5Context*)pNew, pUserData);
+      if( rc!=SQLITE_OK ){
+        if( rc==SQLITE_DONE ) rc = SQLITE_OK;
+        break;
+      }
+    }
+  }
+
+  fts5CloseMethod((sqlite3_vtab_cursor*)pNew);
+  return rc;
+}
+
+static void fts5ApiInvoke(
+  Fts5Auxiliary *pAux,
+  Fts5Cursor *pCsr,
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  assert( pCsr->pAux==0 );
+  pCsr->pAux = pAux;
+  pAux->xFunc(&sFts5Api, (Fts5Context*)pCsr, context, argc, argv);
+  pCsr->pAux = 0;
+}
+
+static Fts5Cursor *fts5CursorFromCsrid(Fts5Global *pGlobal, i64 iCsrId){
+  Fts5Cursor *pCsr;
+  for(pCsr=pGlobal->pCsr; pCsr; pCsr=pCsr->pNext){
+    if( pCsr->iCsrId==iCsrId ) break;
+  }
+  return pCsr;
+}
+
+static void fts5ApiCallback(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+
+  Fts5Auxiliary *pAux;
+  Fts5Cursor *pCsr;
+  i64 iCsrId;
+
+  assert( argc>=1 );
+  pAux = (Fts5Auxiliary*)sqlite3_user_data(context);
+  iCsrId = sqlite3_value_int64(argv[0]);
+
+  pCsr = fts5CursorFromCsrid(pAux->pGlobal, iCsrId);
+  if( pCsr==0 ){
+    char *zErr = sqlite3_mprintf("no such cursor: %lld", iCsrId);
+    sqlite3_result_error(context, zErr, -1);
+    sqlite3_free(zErr);
+  }else{
+    fts5ApiInvoke(pAux, pCsr, context, argc-1, &argv[1]);
+  }
+}
+
+
+/*
+** Given cursor id iId, return a pointer to the corresponding Fts5Index 
+** object. Or NULL If the cursor id does not exist.
+**
+** If successful, set *ppConfig to point to the associated config object 
+** before returning.
+*/
+static Fts5Index *sqlite3Fts5IndexFromCsrid(
+  Fts5Global *pGlobal,            /* FTS5 global context for db handle */
+  i64 iCsrId,                     /* Id of cursor to find */
+  Fts5Config **ppConfig           /* OUT: Configuration object */
+){
+  Fts5Cursor *pCsr;
+  Fts5Table *pTab;
+
+  pCsr = fts5CursorFromCsrid(pGlobal, iCsrId);
+  pTab = (Fts5Table*)pCsr->base.pVtab;
+  *ppConfig = pTab->pConfig;
+
+  return pTab->pIndex;
+}
+
+/*
+** Return a "position-list blob" corresponding to the current position of
+** cursor pCsr via sqlite3_result_blob(). A position-list blob contains
+** the current position-list for each phrase in the query associated with
+** cursor pCsr.
+**
+** A position-list blob begins with (nPhrase-1) varints, where nPhrase is
+** the number of phrases in the query. Following the varints are the
+** concatenated position lists for each phrase, in order.
+**
+** The first varint (if it exists) contains the size of the position list
+** for phrase 0. The second (same disclaimer) contains the size of position
+** list 1. And so on. There is no size field for the final position list,
+** as it can be derived from the total size of the blob.
+*/
+static int fts5PoslistBlob(sqlite3_context *pCtx, Fts5Cursor *pCsr){
+  int i;
+  int rc = SQLITE_OK;
+  int nPhrase = sqlite3Fts5ExprPhraseCount(pCsr->pExpr);
+  Fts5Buffer val;
+
+  memset(&val, 0, sizeof(Fts5Buffer));
+  switch( ((Fts5Table*)(pCsr->base.pVtab))->pConfig->eDetail ){
+    case FTS5_DETAIL_FULL:
+
+      /* Append the varints */
+      for(i=0; i<(nPhrase-1); i++){
+        const u8 *dummy;
+        int nByte = sqlite3Fts5ExprPoslist(pCsr->pExpr, i, &dummy);
+        sqlite3Fts5BufferAppendVarint(&rc, &val, nByte);
+      }
+
+      /* Append the position lists */
+      for(i=0; i<nPhrase; i++){
+        const u8 *pPoslist;
+        int nPoslist;
+        nPoslist = sqlite3Fts5ExprPoslist(pCsr->pExpr, i, &pPoslist);
+        sqlite3Fts5BufferAppendBlob(&rc, &val, nPoslist, pPoslist);
+      }
+      break;
+
+    case FTS5_DETAIL_COLUMNS:
+
+      /* Append the varints */
+      for(i=0; rc==SQLITE_OK && i<(nPhrase-1); i++){
+        const u8 *dummy;
+        int nByte;
+        rc = sqlite3Fts5ExprPhraseCollist(pCsr->pExpr, i, &dummy, &nByte);
+        sqlite3Fts5BufferAppendVarint(&rc, &val, nByte);
+      }
+
+      /* Append the position lists */
+      for(i=0; rc==SQLITE_OK && i<nPhrase; i++){
+        const u8 *pPoslist;
+        int nPoslist;
+        rc = sqlite3Fts5ExprPhraseCollist(pCsr->pExpr, i, &pPoslist, &nPoslist);
+        sqlite3Fts5BufferAppendBlob(&rc, &val, nPoslist, pPoslist);
+      }
+      break;
+
+    default:
+      break;
+  }
+
+  sqlite3_result_blob(pCtx, val.p, val.n, sqlite3_free);
+  return rc;
+}
+
+/* 
+** This is the xColumn method, called by SQLite to request a value from
+** the row that the supplied cursor currently points to.
+*/
+static int fts5ColumnMethod(
+  sqlite3_vtab_cursor *pCursor,   /* Cursor to retrieve value from */
+  sqlite3_context *pCtx,          /* Context for sqlite3_result_xxx() calls */
+  int iCol                        /* Index of column to read value from */
+){
+  Fts5Table *pTab = (Fts5Table*)(pCursor->pVtab);
+  Fts5Config *pConfig = pTab->pConfig;
+  Fts5Cursor *pCsr = (Fts5Cursor*)pCursor;
+  int rc = SQLITE_OK;
+  
+  assert( CsrFlagTest(pCsr, FTS5CSR_EOF)==0 );
+
+  if( pCsr->ePlan==FTS5_PLAN_SPECIAL ){
+    if( iCol==pConfig->nCol ){
+      sqlite3_result_int64(pCtx, pCsr->iSpecial);
+    }
+  }else
+
+  if( iCol==pConfig->nCol ){
+    /* User is requesting the value of the special column with the same name
+    ** as the table. Return the cursor integer id number. This value is only
+    ** useful in that it may be passed as the first argument to an FTS5
+    ** auxiliary function.  */
+    sqlite3_result_int64(pCtx, pCsr->iCsrId);
+  }else if( iCol==pConfig->nCol+1 ){
+
+    /* The value of the "rank" column. */
+    if( pCsr->ePlan==FTS5_PLAN_SOURCE ){
+      fts5PoslistBlob(pCtx, pCsr);
+    }else if( 
+        pCsr->ePlan==FTS5_PLAN_MATCH
+     || pCsr->ePlan==FTS5_PLAN_SORTED_MATCH
+    ){
+      if( pCsr->pRank || SQLITE_OK==(rc = fts5FindRankFunction(pCsr)) ){
+        fts5ApiInvoke(pCsr->pRank, pCsr, pCtx, pCsr->nRankArg, pCsr->apRankArg);
+      }
+    }
+  }else if( !fts5IsContentless(pTab) ){
+    rc = fts5SeekCursor(pCsr, 1);
+    if( rc==SQLITE_OK ){
+      sqlite3_result_value(pCtx, sqlite3_column_value(pCsr->pStmt, iCol+1));
+    }
+  }
+  return rc;
+}
+
+
+/*
+** This routine implements the xFindFunction method for the FTS3
+** virtual table.
+*/
+static int fts5FindFunctionMethod(
+  sqlite3_vtab *pVtab,            /* Virtual table handle */
+  int nUnused,                    /* Number of SQL function arguments */
+  const char *zName,              /* Name of SQL function */
+  void (**pxFunc)(sqlite3_context*,int,sqlite3_value**), /* OUT: Result */
+  void **ppArg                    /* OUT: User data for *pxFunc */
+){
+  Fts5Table *pTab = (Fts5Table*)pVtab;
+  Fts5Auxiliary *pAux;
+
+  UNUSED_PARAM(nUnused);
+  pAux = fts5FindAuxiliary(pTab, zName);
+  if( pAux ){
+    *pxFunc = fts5ApiCallback;
+    *ppArg = (void*)pAux;
+    return 1;
+  }
+
+  /* No function of the specified name was found. Return 0. */
+  return 0;
+}
+
+/*
+** Implementation of FTS5 xRename method. Rename an fts5 table.
+*/
+static int fts5RenameMethod(
+  sqlite3_vtab *pVtab,            /* Virtual table handle */
+  const char *zName               /* New name of table */
+){
+  Fts5Table *pTab = (Fts5Table*)pVtab;
+  return sqlite3Fts5StorageRename(pTab->pStorage, zName);
+}
+
+/*
+** The xSavepoint() method.
+**
+** Flush the contents of the pending-terms table to disk.
+*/
+static int fts5SavepointMethod(sqlite3_vtab *pVtab, int iSavepoint){
+  Fts5Table *pTab = (Fts5Table*)pVtab;
+  UNUSED_PARAM(iSavepoint);  /* Call below is a no-op for NDEBUG builds */
+  fts5CheckTransactionState(pTab, FTS5_SAVEPOINT, iSavepoint);
+  fts5TripCursors(pTab);
+  return sqlite3Fts5StorageSync(pTab->pStorage, 0);
+}
+
+/*
+** The xRelease() method.
+**
+** This is a no-op.
+*/
+static int fts5ReleaseMethod(sqlite3_vtab *pVtab, int iSavepoint){
+  Fts5Table *pTab = (Fts5Table*)pVtab;
+  UNUSED_PARAM(iSavepoint);  /* Call below is a no-op for NDEBUG builds */
+  fts5CheckTransactionState(pTab, FTS5_RELEASE, iSavepoint);
+  fts5TripCursors(pTab);
+  return sqlite3Fts5StorageSync(pTab->pStorage, 0);
+}
+
+/*
+** The xRollbackTo() method.
+**
+** Discard the contents of the pending terms table.
+*/
+static int fts5RollbackToMethod(sqlite3_vtab *pVtab, int iSavepoint){
+  Fts5Table *pTab = (Fts5Table*)pVtab;
+  UNUSED_PARAM(iSavepoint);  /* Call below is a no-op for NDEBUG builds */
+  fts5CheckTransactionState(pTab, FTS5_ROLLBACKTO, iSavepoint);
+  fts5TripCursors(pTab);
+  return sqlite3Fts5StorageRollback(pTab->pStorage);
+}
+
+/*
+** Register a new auxiliary function with global context pGlobal.
+*/
+static int fts5CreateAux(
+  fts5_api *pApi,                 /* Global context (one per db handle) */
+  const char *zName,              /* Name of new function */
+  void *pUserData,                /* User data for aux. function */
+  fts5_extension_function xFunc,  /* Aux. function implementation */
+  void(*xDestroy)(void*)          /* Destructor for pUserData */
+){
+  Fts5Global *pGlobal = (Fts5Global*)pApi;
+  int rc = sqlite3_overload_function(pGlobal->db, zName, -1);
+  if( rc==SQLITE_OK ){
+    Fts5Auxiliary *pAux;
+    int nName;                      /* Size of zName in bytes, including \0 */
+    int nByte;                      /* Bytes of space to allocate */
+
+    nName = (int)strlen(zName) + 1;
+    nByte = sizeof(Fts5Auxiliary) + nName;
+    pAux = (Fts5Auxiliary*)sqlite3_malloc(nByte);
+    if( pAux ){
+      memset(pAux, 0, nByte);
+      pAux->zFunc = (char*)&pAux[1];
+      memcpy(pAux->zFunc, zName, nName);
+      pAux->pGlobal = pGlobal;
+      pAux->pUserData = pUserData;
+      pAux->xFunc = xFunc;
+      pAux->xDestroy = xDestroy;
+      pAux->pNext = pGlobal->pAux;
+      pGlobal->pAux = pAux;
+    }else{
+      rc = SQLITE_NOMEM;
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Register a new tokenizer. This is the implementation of the 
+** fts5_api.xCreateTokenizer() method.
+*/
+static int fts5CreateTokenizer(
+  fts5_api *pApi,                 /* Global context (one per db handle) */
+  const char *zName,              /* Name of new function */
+  void *pUserData,                /* User data for aux. function */
+  fts5_tokenizer *pTokenizer,     /* Tokenizer implementation */
+  void(*xDestroy)(void*)          /* Destructor for pUserData */
+){
+  Fts5Global *pGlobal = (Fts5Global*)pApi;
+  Fts5TokenizerModule *pNew;
+  int nName;                      /* Size of zName and its \0 terminator */
+  int nByte;                      /* Bytes of space to allocate */
+  int rc = SQLITE_OK;
+
+  nName = (int)strlen(zName) + 1;
+  nByte = sizeof(Fts5TokenizerModule) + nName;
+  pNew = (Fts5TokenizerModule*)sqlite3_malloc(nByte);
+  if( pNew ){
+    memset(pNew, 0, nByte);
+    pNew->zName = (char*)&pNew[1];
+    memcpy(pNew->zName, zName, nName);
+    pNew->pUserData = pUserData;
+    pNew->x = *pTokenizer;
+    pNew->xDestroy = xDestroy;
+    pNew->pNext = pGlobal->pTok;
+    pGlobal->pTok = pNew;
+    if( pNew->pNext==0 ){
+      pGlobal->pDfltTok = pNew;
+    }
+  }else{
+    rc = SQLITE_NOMEM;
+  }
+
+  return rc;
+}
+
+static Fts5TokenizerModule *fts5LocateTokenizer(
+  Fts5Global *pGlobal, 
+  const char *zName
+){
+  Fts5TokenizerModule *pMod = 0;
+
+  if( zName==0 ){
+    pMod = pGlobal->pDfltTok;
+  }else{
+    for(pMod=pGlobal->pTok; pMod; pMod=pMod->pNext){
+      if( sqlite3_stricmp(zName, pMod->zName)==0 ) break;
+    }
+  }
+
+  return pMod;
+}
+
+/*
+** Find a tokenizer. This is the implementation of the 
+** fts5_api.xFindTokenizer() method.
+*/
+static int fts5FindTokenizer(
+  fts5_api *pApi,                 /* Global context (one per db handle) */
+  const char *zName,              /* Name of new function */
+  void **ppUserData,
+  fts5_tokenizer *pTokenizer      /* Populate this object */
+){
+  int rc = SQLITE_OK;
+  Fts5TokenizerModule *pMod;
+
+  pMod = fts5LocateTokenizer((Fts5Global*)pApi, zName);
+  if( pMod ){
+    *pTokenizer = pMod->x;
+    *ppUserData = pMod->pUserData;
+  }else{
+    memset(pTokenizer, 0, sizeof(fts5_tokenizer));
+    rc = SQLITE_ERROR;
+  }
+
+  return rc;
+}
+
+static int sqlite3Fts5GetTokenizer(
+  Fts5Global *pGlobal, 
+  const char **azArg,
+  int nArg,
+  Fts5Tokenizer **ppTok,
+  fts5_tokenizer **ppTokApi,
+  char **pzErr
+){
+  Fts5TokenizerModule *pMod;
+  int rc = SQLITE_OK;
+
+  pMod = fts5LocateTokenizer(pGlobal, nArg==0 ? 0 : azArg[0]);
+  if( pMod==0 ){
+    assert( nArg>0 );
+    rc = SQLITE_ERROR;
+    *pzErr = sqlite3_mprintf("no such tokenizer: %s", azArg[0]);
+  }else{
+    rc = pMod->x.xCreate(pMod->pUserData, &azArg[1], (nArg?nArg-1:0), ppTok);
+    *ppTokApi = &pMod->x;
+    if( rc!=SQLITE_OK && pzErr ){
+      *pzErr = sqlite3_mprintf("error in tokenizer constructor");
+    }
+  }
+
+  if( rc!=SQLITE_OK ){
+    *ppTokApi = 0;
+    *ppTok = 0;
+  }
+
+  return rc;
+}
+
+static void fts5ModuleDestroy(void *pCtx){
+  Fts5TokenizerModule *pTok, *pNextTok;
+  Fts5Auxiliary *pAux, *pNextAux;
+  Fts5Global *pGlobal = (Fts5Global*)pCtx;
+
+  for(pAux=pGlobal->pAux; pAux; pAux=pNextAux){
+    pNextAux = pAux->pNext;
+    if( pAux->xDestroy ) pAux->xDestroy(pAux->pUserData);
+    sqlite3_free(pAux);
+  }
+
+  for(pTok=pGlobal->pTok; pTok; pTok=pNextTok){
+    pNextTok = pTok->pNext;
+    if( pTok->xDestroy ) pTok->xDestroy(pTok->pUserData);
+    sqlite3_free(pTok);
+  }
+
+  sqlite3_free(pGlobal);
+}
+
+static void fts5Fts5Func(
+  sqlite3_context *pCtx,          /* Function call context */
+  int nArg,                       /* Number of args */
+  sqlite3_value **apUnused        /* Function arguments */
+){
+  Fts5Global *pGlobal = (Fts5Global*)sqlite3_user_data(pCtx);
+  char buf[8];
+  UNUSED_PARAM2(nArg, apUnused);
+  assert( nArg==0 );
+  assert( sizeof(buf)>=sizeof(pGlobal) );
+  memcpy(buf, (void*)&pGlobal, sizeof(pGlobal));
+  sqlite3_result_blob(pCtx, buf, sizeof(pGlobal), SQLITE_TRANSIENT);
+}
+
+/*
+** Implementation of fts5_source_id() function.
+*/
+static void fts5SourceIdFunc(
+  sqlite3_context *pCtx,          /* Function call context */
+  int nArg,                       /* Number of args */
+  sqlite3_value **apUnused        /* Function arguments */
+){
+  assert( nArg==0 );
+  UNUSED_PARAM2(nArg, apUnused);
+  sqlite3_result_text(pCtx, "fts5: 2016-11-28 19:13:37 bbd85d235f7037c6a033a9690534391ffeacecc8", -1, SQLITE_TRANSIENT);
+}
+
+static int fts5Init(sqlite3 *db){
+  static const sqlite3_module fts5Mod = {
+    /* iVersion      */ 2,
+    /* xCreate       */ fts5CreateMethod,
+    /* xConnect      */ fts5ConnectMethod,
+    /* xBestIndex    */ fts5BestIndexMethod,
+    /* xDisconnect   */ fts5DisconnectMethod,
+    /* xDestroy      */ fts5DestroyMethod,
+    /* xOpen         */ fts5OpenMethod,
+    /* xClose        */ fts5CloseMethod,
+    /* xFilter       */ fts5FilterMethod,
+    /* xNext         */ fts5NextMethod,
+    /* xEof          */ fts5EofMethod,
+    /* xColumn       */ fts5ColumnMethod,
+    /* xRowid        */ fts5RowidMethod,
+    /* xUpdate       */ fts5UpdateMethod,
+    /* xBegin        */ fts5BeginMethod,
+    /* xSync         */ fts5SyncMethod,
+    /* xCommit       */ fts5CommitMethod,
+    /* xRollback     */ fts5RollbackMethod,
+    /* xFindFunction */ fts5FindFunctionMethod,
+    /* xRename       */ fts5RenameMethod,
+    /* xSavepoint    */ fts5SavepointMethod,
+    /* xRelease      */ fts5ReleaseMethod,
+    /* xRollbackTo   */ fts5RollbackToMethod,
+  };
+
+  int rc;
+  Fts5Global *pGlobal = 0;
+
+  pGlobal = (Fts5Global*)sqlite3_malloc(sizeof(Fts5Global));
+  if( pGlobal==0 ){
+    rc = SQLITE_NOMEM;
+  }else{
+    void *p = (void*)pGlobal;
+    memset(pGlobal, 0, sizeof(Fts5Global));
+    pGlobal->db = db;
+    pGlobal->api.iVersion = 2;
+    pGlobal->api.xCreateFunction = fts5CreateAux;
+    pGlobal->api.xCreateTokenizer = fts5CreateTokenizer;
+    pGlobal->api.xFindTokenizer = fts5FindTokenizer;
+    rc = sqlite3_create_module_v2(db, "fts5", &fts5Mod, p, fts5ModuleDestroy);
+    if( rc==SQLITE_OK ) rc = sqlite3Fts5IndexInit(db);
+    if( rc==SQLITE_OK ) rc = sqlite3Fts5ExprInit(pGlobal, db);
+    if( rc==SQLITE_OK ) rc = sqlite3Fts5AuxInit(&pGlobal->api);
+    if( rc==SQLITE_OK ) rc = sqlite3Fts5TokenizerInit(&pGlobal->api);
+    if( rc==SQLITE_OK ) rc = sqlite3Fts5VocabInit(pGlobal, db);
+    if( rc==SQLITE_OK ){
+      rc = sqlite3_create_function(
+          db, "fts5", 0, SQLITE_UTF8, p, fts5Fts5Func, 0, 0
+      );
+    }
+    if( rc==SQLITE_OK ){
+      rc = sqlite3_create_function(
+          db, "fts5_source_id", 0, SQLITE_UTF8, p, fts5SourceIdFunc, 0, 0
+      );
+    }
+  }
+
+  /* If SQLITE_FTS5_ENABLE_TEST_MI is defined, assume that the file
+  ** fts5_test_mi.c is compiled and linked into the executable. And call
+  ** its entry point to enable the matchinfo() demo.  */
+#ifdef SQLITE_FTS5_ENABLE_TEST_MI
+  if( rc==SQLITE_OK ){
+    extern int sqlite3Fts5TestRegisterMatchinfo(sqlite3*);
+    rc = sqlite3Fts5TestRegisterMatchinfo(db);
+  }
+#endif
+
+  return rc;
+}
+
+/*
+** The following functions are used to register the module with SQLite. If
+** this module is being built as part of the SQLite core (SQLITE_CORE is
+** defined), then sqlite3_open() will call sqlite3Fts5Init() directly.
+**
+** Or, if this module is being built as a loadable extension, 
+** sqlite3Fts5Init() is omitted and the two standard entry points
+** sqlite3_fts_init() and sqlite3_fts5_init() defined instead.
+*/
+#ifndef SQLITE_CORE
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+SQLITE_API int sqlite3_fts_init(
+  sqlite3 *db,
+  char **pzErrMsg,
+  const sqlite3_api_routines *pApi
+){
+  SQLITE_EXTENSION_INIT2(pApi);
+  (void)pzErrMsg;  /* Unused parameter */
+  return fts5Init(db);
+}
+
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+SQLITE_API int sqlite3_fts5_init(
+  sqlite3 *db,
+  char **pzErrMsg,
+  const sqlite3_api_routines *pApi
+){
+  SQLITE_EXTENSION_INIT2(pApi);
+  (void)pzErrMsg;  /* Unused parameter */
+  return fts5Init(db);
+}
+#else
+SQLITE_PRIVATE int sqlite3Fts5Init(sqlite3 *db){
+  return fts5Init(db);
+}
+#endif
+
+/*
+** 2014 May 31
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+*/
+
+
+
+/* #include "fts5Int.h" */
+
+struct Fts5Storage {
+  Fts5Config *pConfig;
+  Fts5Index *pIndex;
+  int bTotalsValid;               /* True if nTotalRow/aTotalSize[] are valid */
+  i64 nTotalRow;                  /* Total number of rows in FTS table */
+  i64 *aTotalSize;                /* Total sizes of each column */ 
+  sqlite3_stmt *aStmt[11];
+};
+
+
+#if FTS5_STMT_SCAN_ASC!=0 
+# error "FTS5_STMT_SCAN_ASC mismatch" 
+#endif
+#if FTS5_STMT_SCAN_DESC!=1 
+# error "FTS5_STMT_SCAN_DESC mismatch" 
+#endif
+#if FTS5_STMT_LOOKUP!=2
+# error "FTS5_STMT_LOOKUP mismatch" 
+#endif
+
+#define FTS5_STMT_INSERT_CONTENT  3
+#define FTS5_STMT_REPLACE_CONTENT 4
+#define FTS5_STMT_DELETE_CONTENT  5
+#define FTS5_STMT_REPLACE_DOCSIZE  6
+#define FTS5_STMT_DELETE_DOCSIZE  7
+#define FTS5_STMT_LOOKUP_DOCSIZE  8
+#define FTS5_STMT_REPLACE_CONFIG 9
+#define FTS5_STMT_SCAN 10
+
+/*
+** Prepare the two insert statements - Fts5Storage.pInsertContent and
+** Fts5Storage.pInsertDocsize - if they have not already been prepared.
+** Return SQLITE_OK if successful, or an SQLite error code if an error
+** occurs.
+*/
+static int fts5StorageGetStmt(
+  Fts5Storage *p,                 /* Storage handle */
+  int eStmt,                      /* FTS5_STMT_XXX constant */
+  sqlite3_stmt **ppStmt,          /* OUT: Prepared statement handle */
+  char **pzErrMsg                 /* OUT: Error message (if any) */
+){
+  int rc = SQLITE_OK;
+
+  /* If there is no %_docsize table, there should be no requests for 
+  ** statements to operate on it.  */
+  assert( p->pConfig->bColumnsize || (
+        eStmt!=FTS5_STMT_REPLACE_DOCSIZE 
+     && eStmt!=FTS5_STMT_DELETE_DOCSIZE 
+     && eStmt!=FTS5_STMT_LOOKUP_DOCSIZE 
+  ));
+
+  assert( eStmt>=0 && eStmt<ArraySize(p->aStmt) );
+  if( p->aStmt[eStmt]==0 ){
+    const char *azStmt[] = {
+      "SELECT %s FROM %s T WHERE T.%Q >= ? AND T.%Q <= ? ORDER BY T.%Q ASC",
+      "SELECT %s FROM %s T WHERE T.%Q <= ? AND T.%Q >= ? ORDER BY T.%Q DESC",
+      "SELECT %s FROM %s T WHERE T.%Q=?",               /* LOOKUP  */
+
+      "INSERT INTO %Q.'%q_content' VALUES(%s)",         /* INSERT_CONTENT  */
+      "REPLACE INTO %Q.'%q_content' VALUES(%s)",        /* REPLACE_CONTENT */
+      "DELETE FROM %Q.'%q_content' WHERE id=?",         /* DELETE_CONTENT  */
+      "REPLACE INTO %Q.'%q_docsize' VALUES(?,?)",       /* REPLACE_DOCSIZE  */
+      "DELETE FROM %Q.'%q_docsize' WHERE id=?",         /* DELETE_DOCSIZE  */
+
+      "SELECT sz FROM %Q.'%q_docsize' WHERE id=?",      /* LOOKUP_DOCSIZE  */
+
+      "REPLACE INTO %Q.'%q_config' VALUES(?,?)",        /* REPLACE_CONFIG */
+      "SELECT %s FROM %s AS T",                         /* SCAN */
+    };
+    Fts5Config *pC = p->pConfig;
+    char *zSql = 0;
+
+    switch( eStmt ){
+      case FTS5_STMT_SCAN:
+        zSql = sqlite3_mprintf(azStmt[eStmt], 
+            pC->zContentExprlist, pC->zContent
+        );
+        break;
+
+      case FTS5_STMT_SCAN_ASC:
+      case FTS5_STMT_SCAN_DESC:
+        zSql = sqlite3_mprintf(azStmt[eStmt], pC->zContentExprlist, 
+            pC->zContent, pC->zContentRowid, pC->zContentRowid,
+            pC->zContentRowid
+        );
+        break;
+
+      case FTS5_STMT_LOOKUP:
+        zSql = sqlite3_mprintf(azStmt[eStmt], 
+            pC->zContentExprlist, pC->zContent, pC->zContentRowid
+        );
+        break;
+
+      case FTS5_STMT_INSERT_CONTENT: 
+      case FTS5_STMT_REPLACE_CONTENT: {
+        int nCol = pC->nCol + 1;
+        char *zBind;
+        int i;
+
+        zBind = sqlite3_malloc(1 + nCol*2);
+        if( zBind ){
+          for(i=0; i<nCol; i++){
+            zBind[i*2] = '?';
+            zBind[i*2 + 1] = ',';
+          }
+          zBind[i*2-1] = '\0';
+          zSql = sqlite3_mprintf(azStmt[eStmt], pC->zDb, pC->zName, zBind);
+          sqlite3_free(zBind);
+        }
+        break;
+      }
+
+      default:
+        zSql = sqlite3_mprintf(azStmt[eStmt], pC->zDb, pC->zName);
+        break;
+    }
+
+    if( zSql==0 ){
+      rc = SQLITE_NOMEM;
+    }else{
+      rc = sqlite3_prepare_v2(pC->db, zSql, -1, &p->aStmt[eStmt], 0);
+      sqlite3_free(zSql);
+      if( rc!=SQLITE_OK && pzErrMsg ){
+        *pzErrMsg = sqlite3_mprintf("%s", sqlite3_errmsg(pC->db));
+      }
+    }
+  }
+
+  *ppStmt = p->aStmt[eStmt];
+  sqlite3_reset(*ppStmt);
+  return rc;
+}
+
+
+static int fts5ExecPrintf(
+  sqlite3 *db,
+  char **pzErr,
+  const char *zFormat,
+  ...
+){
+  int rc;
+  va_list ap;                     /* ... printf arguments */
+  char *zSql;
+
+  va_start(ap, zFormat);
+  zSql = sqlite3_vmprintf(zFormat, ap);
+
+  if( zSql==0 ){
+    rc = SQLITE_NOMEM;
+  }else{
+    rc = sqlite3_exec(db, zSql, 0, 0, pzErr);
+    sqlite3_free(zSql);
+  }
+
+  va_end(ap);
+  return rc;
+}
+
+/*
+** Drop all shadow tables. Return SQLITE_OK if successful or an SQLite error
+** code otherwise.
+*/
+static int sqlite3Fts5DropAll(Fts5Config *pConfig){
+  int rc = fts5ExecPrintf(pConfig->db, 0, 
+      "DROP TABLE IF EXISTS %Q.'%q_data';"
+      "DROP TABLE IF EXISTS %Q.'%q_idx';"
+      "DROP TABLE IF EXISTS %Q.'%q_config';",
+      pConfig->zDb, pConfig->zName,
+      pConfig->zDb, pConfig->zName,
+      pConfig->zDb, pConfig->zName
+  );
+  if( rc==SQLITE_OK && pConfig->bColumnsize ){
+    rc = fts5ExecPrintf(pConfig->db, 0, 
+        "DROP TABLE IF EXISTS %Q.'%q_docsize';",
+        pConfig->zDb, pConfig->zName
+    );
+  }
+  if( rc==SQLITE_OK && pConfig->eContent==FTS5_CONTENT_NORMAL ){
+    rc = fts5ExecPrintf(pConfig->db, 0, 
+        "DROP TABLE IF EXISTS %Q.'%q_content';",
+        pConfig->zDb, pConfig->zName
+    );
+  }
+  return rc;
+}
+
+static void fts5StorageRenameOne(
+  Fts5Config *pConfig,            /* Current FTS5 configuration */
+  int *pRc,                       /* IN/OUT: Error code */
+  const char *zTail,              /* Tail of table name e.g. "data", "config" */
+  const char *zName               /* New name of FTS5 table */
+){
+  if( *pRc==SQLITE_OK ){
+    *pRc = fts5ExecPrintf(pConfig->db, 0, 
+        "ALTER TABLE %Q.'%q_%s' RENAME TO '%q_%s';",
+        pConfig->zDb, pConfig->zName, zTail, zName, zTail
+    );
+  }
+}
+
+static int sqlite3Fts5StorageRename(Fts5Storage *pStorage, const char *zName){
+  Fts5Config *pConfig = pStorage->pConfig;
+  int rc = sqlite3Fts5StorageSync(pStorage, 1);
+
+  fts5StorageRenameOne(pConfig, &rc, "data", zName);
+  fts5StorageRenameOne(pConfig, &rc, "idx", zName);
+  fts5StorageRenameOne(pConfig, &rc, "config", zName);
+  if( pConfig->bColumnsize ){
+    fts5StorageRenameOne(pConfig, &rc, "docsize", zName);
+  }
+  if( pConfig->eContent==FTS5_CONTENT_NORMAL ){
+    fts5StorageRenameOne(pConfig, &rc, "content", zName);
+  }
+  return rc;
+}
+
+/*
+** Create the shadow table named zPost, with definition zDefn. Return
+** SQLITE_OK if successful, or an SQLite error code otherwise.
+*/
+static int sqlite3Fts5CreateTable(
+  Fts5Config *pConfig,            /* FTS5 configuration */
+  const char *zPost,              /* Shadow table to create (e.g. "content") */
+  const char *zDefn,              /* Columns etc. for shadow table */
+  int bWithout,                   /* True for without rowid */
+  char **pzErr                    /* OUT: Error message */
+){
+  int rc;
+  char *zErr = 0;
+
+  rc = fts5ExecPrintf(pConfig->db, &zErr, "CREATE TABLE %Q.'%q_%q'(%s)%s",
+      pConfig->zDb, pConfig->zName, zPost, zDefn, 
+#ifndef SQLITE_FTS5_NO_WITHOUT_ROWID
+      bWithout?" WITHOUT ROWID":
+#endif
+      ""
+  );
+  if( zErr ){
+    *pzErr = sqlite3_mprintf(
+        "fts5: error creating shadow table %q_%s: %s", 
+        pConfig->zName, zPost, zErr
+    );
+    sqlite3_free(zErr);
+  }
+
+  return rc;
+}
+
+/*
+** Open a new Fts5Index handle. If the bCreate argument is true, create
+** and initialize the underlying tables 
+**
+** If successful, set *pp to point to the new object and return SQLITE_OK.
+** Otherwise, set *pp to NULL and return an SQLite error code.
+*/
+static int sqlite3Fts5StorageOpen(
+  Fts5Config *pConfig, 
+  Fts5Index *pIndex, 
+  int bCreate, 
+  Fts5Storage **pp,
+  char **pzErr                    /* OUT: Error message */
+){
+  int rc = SQLITE_OK;
+  Fts5Storage *p;                 /* New object */
+  int nByte;                      /* Bytes of space to allocate */
+
+  nByte = sizeof(Fts5Storage)               /* Fts5Storage object */
+        + pConfig->nCol * sizeof(i64);      /* Fts5Storage.aTotalSize[] */
+  *pp = p = (Fts5Storage*)sqlite3_malloc(nByte);
+  if( !p ) return SQLITE_NOMEM;
+
+  memset(p, 0, nByte);
+  p->aTotalSize = (i64*)&p[1];
+  p->pConfig = pConfig;
+  p->pIndex = pIndex;
+
+  if( bCreate ){
+    if( pConfig->eContent==FTS5_CONTENT_NORMAL ){
+      int nDefn = 32 + pConfig->nCol*10;
+      char *zDefn = sqlite3_malloc(32 + pConfig->nCol * 10);
+      if( zDefn==0 ){
+        rc = SQLITE_NOMEM;
+      }else{
+        int i;
+        int iOff;
+        sqlite3_snprintf(nDefn, zDefn, "id INTEGER PRIMARY KEY");
+        iOff = (int)strlen(zDefn);
+        for(i=0; i<pConfig->nCol; i++){
+          sqlite3_snprintf(nDefn-iOff, &zDefn[iOff], ", c%d", i);
+          iOff += (int)strlen(&zDefn[iOff]);
+        }
+        rc = sqlite3Fts5CreateTable(pConfig, "content", zDefn, 0, pzErr);
+      }
+      sqlite3_free(zDefn);
+    }
+
+    if( rc==SQLITE_OK && pConfig->bColumnsize ){
+      rc = sqlite3Fts5CreateTable(
+          pConfig, "docsize", "id INTEGER PRIMARY KEY, sz BLOB", 0, pzErr
+      );
+    }
+    if( rc==SQLITE_OK ){
+      rc = sqlite3Fts5CreateTable(
+          pConfig, "config", "k PRIMARY KEY, v", 1, pzErr
+      );
+    }
+    if( rc==SQLITE_OK ){
+      rc = sqlite3Fts5StorageConfigValue(p, "version", 0, FTS5_CURRENT_VERSION);
+    }
+  }
+
+  if( rc ){
+    sqlite3Fts5StorageClose(p);
+    *pp = 0;
+  }
+  return rc;
+}
+
+/*
+** Close a handle opened by an earlier call to sqlite3Fts5StorageOpen().
+*/
+static int sqlite3Fts5StorageClose(Fts5Storage *p){
+  int rc = SQLITE_OK;
+  if( p ){
+    int i;
+
+    /* Finalize all SQL statements */
+    for(i=0; i<ArraySize(p->aStmt); i++){
+      sqlite3_finalize(p->aStmt[i]);
+    }
+
+    sqlite3_free(p);
+  }
+  return rc;
+}
+
+typedef struct Fts5InsertCtx Fts5InsertCtx;
+struct Fts5InsertCtx {
+  Fts5Storage *pStorage;
+  int iCol;
+  int szCol;                      /* Size of column value in tokens */
+};
+
+/*
+** Tokenization callback used when inserting tokens into the FTS index.
+*/
+static int fts5StorageInsertCallback(
+  void *pContext,                 /* Pointer to Fts5InsertCtx object */
+  int tflags,
+  const char *pToken,             /* Buffer containing token */
+  int nToken,                     /* Size of token in bytes */
+  int iUnused1,                   /* Start offset of token */
+  int iUnused2                    /* End offset of token */
+){
+  Fts5InsertCtx *pCtx = (Fts5InsertCtx*)pContext;
+  Fts5Index *pIdx = pCtx->pStorage->pIndex;
+  UNUSED_PARAM2(iUnused1, iUnused2);
+  if( nToken>FTS5_MAX_TOKEN_SIZE ) nToken = FTS5_MAX_TOKEN_SIZE;
+  if( (tflags & FTS5_TOKEN_COLOCATED)==0 || pCtx->szCol==0 ){
+    pCtx->szCol++;
+  }
+  return sqlite3Fts5IndexWrite(pIdx, pCtx->iCol, pCtx->szCol-1, pToken, nToken);
+}
+
+/*
+** If a row with rowid iDel is present in the %_content table, add the
+** delete-markers to the FTS index necessary to delete it. Do not actually
+** remove the %_content row at this time though.
+*/
+static int fts5StorageDeleteFromIndex(
+  Fts5Storage *p, 
+  i64 iDel, 
+  sqlite3_value **apVal
+){
+  Fts5Config *pConfig = p->pConfig;
+  sqlite3_stmt *pSeek = 0;        /* SELECT to read row iDel from %_data */
+  int rc;                         /* Return code */
+  int rc2;                        /* sqlite3_reset() return code */
+  int iCol;
+  Fts5InsertCtx ctx;
+
+  if( apVal==0 ){
+    rc = fts5StorageGetStmt(p, FTS5_STMT_LOOKUP, &pSeek, 0);
+    if( rc!=SQLITE_OK ) return rc;
+    sqlite3_bind_int64(pSeek, 1, iDel);
+    if( sqlite3_step(pSeek)!=SQLITE_ROW ){
+      return sqlite3_reset(pSeek);
+    }
+  }
+
+  ctx.pStorage = p;
+  ctx.iCol = -1;
+  rc = sqlite3Fts5IndexBeginWrite(p->pIndex, 1, iDel);
+  for(iCol=1; rc==SQLITE_OK && iCol<=pConfig->nCol; iCol++){
+    if( pConfig->abUnindexed[iCol-1]==0 ){
+      const char *zText;
+      int nText;
+      if( pSeek ){
+        zText = (const char*)sqlite3_column_text(pSeek, iCol);
+        nText = sqlite3_column_bytes(pSeek, iCol);
+      }else{
+        zText = (const char*)sqlite3_value_text(apVal[iCol-1]);
+        nText = sqlite3_value_bytes(apVal[iCol-1]);
+      }
+      ctx.szCol = 0;
+      rc = sqlite3Fts5Tokenize(pConfig, FTS5_TOKENIZE_DOCUMENT, 
+          zText, nText, (void*)&ctx, fts5StorageInsertCallback
+      );
+      p->aTotalSize[iCol-1] -= (i64)ctx.szCol;
+    }
+  }
+  p->nTotalRow--;
+
+  rc2 = sqlite3_reset(pSeek);
+  if( rc==SQLITE_OK ) rc = rc2;
+  return rc;
+}
+
+
+/*
+** Insert a record into the %_docsize table. Specifically, do:
+**
+**   INSERT OR REPLACE INTO %_docsize(id, sz) VALUES(iRowid, pBuf);
+**
+** If there is no %_docsize table (as happens if the columnsize=0 option
+** is specified when the FTS5 table is created), this function is a no-op.
+*/
+static int fts5StorageInsertDocsize(
+  Fts5Storage *p,                 /* Storage module to write to */
+  i64 iRowid,                     /* id value */
+  Fts5Buffer *pBuf                /* sz value */
+){
+  int rc = SQLITE_OK;
+  if( p->pConfig->bColumnsize ){
+    sqlite3_stmt *pReplace = 0;
+    rc = fts5StorageGetStmt(p, FTS5_STMT_REPLACE_DOCSIZE, &pReplace, 0);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_int64(pReplace, 1, iRowid);
+      sqlite3_bind_blob(pReplace, 2, pBuf->p, pBuf->n, SQLITE_STATIC);
+      sqlite3_step(pReplace);
+      rc = sqlite3_reset(pReplace);
+    }
+  }
+  return rc;
+}
+
+/*
+** Load the contents of the "averages" record from disk into the 
+** p->nTotalRow and p->aTotalSize[] variables. If successful, and if
+** argument bCache is true, set the p->bTotalsValid flag to indicate
+** that the contents of aTotalSize[] and nTotalRow are valid until
+** further notice.
+**
+** Return SQLITE_OK if successful, or an SQLite error code if an error
+** occurs.
+*/
+static int fts5StorageLoadTotals(Fts5Storage *p, int bCache){
+  int rc = SQLITE_OK;
+  if( p->bTotalsValid==0 ){
+    rc = sqlite3Fts5IndexGetAverages(p->pIndex, &p->nTotalRow, p->aTotalSize);
+    p->bTotalsValid = bCache;
+  }
+  return rc;
+}
+
+/*
+** Store the current contents of the p->nTotalRow and p->aTotalSize[] 
+** variables in the "averages" record on disk.
+**
+** Return SQLITE_OK if successful, or an SQLite error code if an error
+** occurs.
+*/
+static int fts5StorageSaveTotals(Fts5Storage *p){
+  int nCol = p->pConfig->nCol;
+  int i;
+  Fts5Buffer buf;
+  int rc = SQLITE_OK;
+  memset(&buf, 0, sizeof(buf));
+
+  sqlite3Fts5BufferAppendVarint(&rc, &buf, p->nTotalRow);
+  for(i=0; i<nCol; i++){
+    sqlite3Fts5BufferAppendVarint(&rc, &buf, p->aTotalSize[i]);
+  }
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts5IndexSetAverages(p->pIndex, buf.p, buf.n);
+  }
+  sqlite3_free(buf.p);
+
+  return rc;
+}
+
+/*
+** Remove a row from the FTS table.
+*/
+static int sqlite3Fts5StorageDelete(Fts5Storage *p, i64 iDel, sqlite3_value **apVal){
+  Fts5Config *pConfig = p->pConfig;
+  int rc;
+  sqlite3_stmt *pDel = 0;
+
+  assert( pConfig->eContent!=FTS5_CONTENT_NORMAL || apVal==0 );
+  rc = fts5StorageLoadTotals(p, 1);
+
+  /* Delete the index records */
+  if( rc==SQLITE_OK ){
+    rc = fts5StorageDeleteFromIndex(p, iDel, apVal);
+  }
+
+  /* Delete the %_docsize record */
+  if( rc==SQLITE_OK && pConfig->bColumnsize ){
+    rc = fts5StorageGetStmt(p, FTS5_STMT_DELETE_DOCSIZE, &pDel, 0);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_int64(pDel, 1, iDel);
+      sqlite3_step(pDel);
+      rc = sqlite3_reset(pDel);
+    }
+  }
+
+  /* Delete the %_content record */
+  if( pConfig->eContent==FTS5_CONTENT_NORMAL ){
+    if( rc==SQLITE_OK ){
+      rc = fts5StorageGetStmt(p, FTS5_STMT_DELETE_CONTENT, &pDel, 0);
+    }
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_int64(pDel, 1, iDel);
+      sqlite3_step(pDel);
+      rc = sqlite3_reset(pDel);
+    }
+  }
+
+  /* Write the averages record */
+  if( rc==SQLITE_OK ){
+    rc = fts5StorageSaveTotals(p);
+  }
+
+  return rc;
+}
+
+/*
+** Delete all entries in the FTS5 index.
+*/
+static int sqlite3Fts5StorageDeleteAll(Fts5Storage *p){
+  Fts5Config *pConfig = p->pConfig;
+  int rc;
+
+  /* Delete the contents of the %_data and %_docsize tables. */
+  rc = fts5ExecPrintf(pConfig->db, 0,
+      "DELETE FROM %Q.'%q_data';" 
+      "DELETE FROM %Q.'%q_idx';",
+      pConfig->zDb, pConfig->zName,
+      pConfig->zDb, pConfig->zName
+  );
+  if( rc==SQLITE_OK && pConfig->bColumnsize ){
+    rc = fts5ExecPrintf(pConfig->db, 0,
+        "DELETE FROM %Q.'%q_docsize';",
+        pConfig->zDb, pConfig->zName
+    );
+  }
+
+  /* Reinitialize the %_data table. This call creates the initial structure
+  ** and averages records.  */
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts5IndexReinit(p->pIndex);
+  }
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts5StorageConfigValue(p, "version", 0, FTS5_CURRENT_VERSION);
+  }
+  return rc;
+}
+
+static int sqlite3Fts5StorageRebuild(Fts5Storage *p){
+  Fts5Buffer buf = {0,0,0};
+  Fts5Config *pConfig = p->pConfig;
+  sqlite3_stmt *pScan = 0;
+  Fts5InsertCtx ctx;
+  int rc;
+
+  memset(&ctx, 0, sizeof(Fts5InsertCtx));
+  ctx.pStorage = p;
+  rc = sqlite3Fts5StorageDeleteAll(p);
+  if( rc==SQLITE_OK ){
+    rc = fts5StorageLoadTotals(p, 1);
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = fts5StorageGetStmt(p, FTS5_STMT_SCAN, &pScan, 0);
+  }
+
+  while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pScan) ){
+    i64 iRowid = sqlite3_column_int64(pScan, 0);
+
+    sqlite3Fts5BufferZero(&buf);
+    rc = sqlite3Fts5IndexBeginWrite(p->pIndex, 0, iRowid);
+    for(ctx.iCol=0; rc==SQLITE_OK && ctx.iCol<pConfig->nCol; ctx.iCol++){
+      ctx.szCol = 0;
+      if( pConfig->abUnindexed[ctx.iCol]==0 ){
+        rc = sqlite3Fts5Tokenize(pConfig, 
+            FTS5_TOKENIZE_DOCUMENT,
+            (const char*)sqlite3_column_text(pScan, ctx.iCol+1),
+            sqlite3_column_bytes(pScan, ctx.iCol+1),
+            (void*)&ctx,
+            fts5StorageInsertCallback
+        );
+      }
+      sqlite3Fts5BufferAppendVarint(&rc, &buf, ctx.szCol);
+      p->aTotalSize[ctx.iCol] += (i64)ctx.szCol;
+    }
+    p->nTotalRow++;
+
+    if( rc==SQLITE_OK ){
+      rc = fts5StorageInsertDocsize(p, iRowid, &buf);
+    }
+  }
+  sqlite3_free(buf.p);
+
+  /* Write the averages record */
+  if( rc==SQLITE_OK ){
+    rc = fts5StorageSaveTotals(p);
+  }
+  return rc;
+}
+
+static int sqlite3Fts5StorageOptimize(Fts5Storage *p){
+  return sqlite3Fts5IndexOptimize(p->pIndex);
+}
+
+static int sqlite3Fts5StorageMerge(Fts5Storage *p, int nMerge){
+  return sqlite3Fts5IndexMerge(p->pIndex, nMerge);
+}
+
+static int sqlite3Fts5StorageReset(Fts5Storage *p){
+  return sqlite3Fts5IndexReset(p->pIndex);
+}
+
+/*
+** Allocate a new rowid. This is used for "external content" tables when
+** a NULL value is inserted into the rowid column. The new rowid is allocated
+** by inserting a dummy row into the %_docsize table. The dummy will be
+** overwritten later.
+**
+** If the %_docsize table does not exist, SQLITE_MISMATCH is returned. In
+** this case the user is required to provide a rowid explicitly.
+*/
+static int fts5StorageNewRowid(Fts5Storage *p, i64 *piRowid){
+  int rc = SQLITE_MISMATCH;
+  if( p->pConfig->bColumnsize ){
+    sqlite3_stmt *pReplace = 0;
+    rc = fts5StorageGetStmt(p, FTS5_STMT_REPLACE_DOCSIZE, &pReplace, 0);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_null(pReplace, 1);
+      sqlite3_bind_null(pReplace, 2);
+      sqlite3_step(pReplace);
+      rc = sqlite3_reset(pReplace);
+    }
+    if( rc==SQLITE_OK ){
+      *piRowid = sqlite3_last_insert_rowid(p->pConfig->db);
+    }
+  }
+  return rc;
+}
+
+/*
+** Insert a new row into the FTS content table.
+*/
+static int sqlite3Fts5StorageContentInsert(
+  Fts5Storage *p, 
+  sqlite3_value **apVal, 
+  i64 *piRowid
+){
+  Fts5Config *pConfig = p->pConfig;
+  int rc = SQLITE_OK;
+
+  /* Insert the new row into the %_content table. */
+  if( pConfig->eContent!=FTS5_CONTENT_NORMAL ){
+    if( sqlite3_value_type(apVal[1])==SQLITE_INTEGER ){
+      *piRowid = sqlite3_value_int64(apVal[1]);
+    }else{
+      rc = fts5StorageNewRowid(p, piRowid);
+    }
+  }else{
+    sqlite3_stmt *pInsert = 0;    /* Statement to write %_content table */
+    int i;                        /* Counter variable */
+    rc = fts5StorageGetStmt(p, FTS5_STMT_INSERT_CONTENT, &pInsert, 0);
+    for(i=1; rc==SQLITE_OK && i<=pConfig->nCol+1; i++){
+      rc = sqlite3_bind_value(pInsert, i, apVal[i]);
+    }
+    if( rc==SQLITE_OK ){
+      sqlite3_step(pInsert);
+      rc = sqlite3_reset(pInsert);
+    }
+    *piRowid = sqlite3_last_insert_rowid(pConfig->db);
+  }
+
+  return rc;
+}
+
+/*
+** Insert new entries into the FTS index and %_docsize table.
+*/
+static int sqlite3Fts5StorageIndexInsert(
+  Fts5Storage *p, 
+  sqlite3_value **apVal, 
+  i64 iRowid
+){
+  Fts5Config *pConfig = p->pConfig;
+  int rc = SQLITE_OK;             /* Return code */
+  Fts5InsertCtx ctx;              /* Tokenization callback context object */
+  Fts5Buffer buf;                 /* Buffer used to build up %_docsize blob */
+
+  memset(&buf, 0, sizeof(Fts5Buffer));
+  ctx.pStorage = p;
+  rc = fts5StorageLoadTotals(p, 1);
+
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts5IndexBeginWrite(p->pIndex, 0, iRowid);
+  }
+  for(ctx.iCol=0; rc==SQLITE_OK && ctx.iCol<pConfig->nCol; ctx.iCol++){
+    ctx.szCol = 0;
+    if( pConfig->abUnindexed[ctx.iCol]==0 ){
+      rc = sqlite3Fts5Tokenize(pConfig, 
+          FTS5_TOKENIZE_DOCUMENT,
+          (const char*)sqlite3_value_text(apVal[ctx.iCol+2]),
+          sqlite3_value_bytes(apVal[ctx.iCol+2]),
+          (void*)&ctx,
+          fts5StorageInsertCallback
+      );
+    }
+    sqlite3Fts5BufferAppendVarint(&rc, &buf, ctx.szCol);
+    p->aTotalSize[ctx.iCol] += (i64)ctx.szCol;
+  }
+  p->nTotalRow++;
+
+  /* Write the %_docsize record */
+  if( rc==SQLITE_OK ){
+    rc = fts5StorageInsertDocsize(p, iRowid, &buf);
+  }
+  sqlite3_free(buf.p);
+
+  /* Write the averages record */
+  if( rc==SQLITE_OK ){
+    rc = fts5StorageSaveTotals(p);
+  }
+
+  return rc;
+}
+
+static int fts5StorageCount(Fts5Storage *p, const char *zSuffix, i64 *pnRow){
+  Fts5Config *pConfig = p->pConfig;
+  char *zSql;
+  int rc;
+
+  zSql = sqlite3_mprintf("SELECT count(*) FROM %Q.'%q_%s'", 
+      pConfig->zDb, pConfig->zName, zSuffix
+  );
+  if( zSql==0 ){
+    rc = SQLITE_NOMEM;
+  }else{
+    sqlite3_stmt *pCnt = 0;
+    rc = sqlite3_prepare_v2(pConfig->db, zSql, -1, &pCnt, 0);
+    if( rc==SQLITE_OK ){
+      if( SQLITE_ROW==sqlite3_step(pCnt) ){
+        *pnRow = sqlite3_column_int64(pCnt, 0);
+      }
+      rc = sqlite3_finalize(pCnt);
+    }
+  }
+
+  sqlite3_free(zSql);
+  return rc;
+}
+
+/*
+** Context object used by sqlite3Fts5StorageIntegrity().
+*/
+typedef struct Fts5IntegrityCtx Fts5IntegrityCtx;
+struct Fts5IntegrityCtx {
+  i64 iRowid;
+  int iCol;
+  int szCol;
+  u64 cksum;
+  Fts5Termset *pTermset;
+  Fts5Config *pConfig;
+};
+
+
+/*
+** Tokenization callback used by integrity check.
+*/
+static int fts5StorageIntegrityCallback(
+  void *pContext,                 /* Pointer to Fts5IntegrityCtx object */
+  int tflags,
+  const char *pToken,             /* Buffer containing token */
+  int nToken,                     /* Size of token in bytes */
+  int iUnused1,                   /* Start offset of token */
+  int iUnused2                    /* End offset of token */
+){
+  Fts5IntegrityCtx *pCtx = (Fts5IntegrityCtx*)pContext;
+  Fts5Termset *pTermset = pCtx->pTermset;
+  int bPresent;
+  int ii;
+  int rc = SQLITE_OK;
+  int iPos;
+  int iCol;
+
+  UNUSED_PARAM2(iUnused1, iUnused2);
+  if( nToken>FTS5_MAX_TOKEN_SIZE ) nToken = FTS5_MAX_TOKEN_SIZE;
+
+  if( (tflags & FTS5_TOKEN_COLOCATED)==0 || pCtx->szCol==0 ){
+    pCtx->szCol++;
+  }
+
+  switch( pCtx->pConfig->eDetail ){
+    case FTS5_DETAIL_FULL:
+      iPos = pCtx->szCol-1;
+      iCol = pCtx->iCol;
+      break;
+
+    case FTS5_DETAIL_COLUMNS:
+      iPos = pCtx->iCol;
+      iCol = 0;
+      break;
+
+    default:
+      assert( pCtx->pConfig->eDetail==FTS5_DETAIL_NONE );
+      iPos = 0;
+      iCol = 0;
+      break;
+  }
+
+  rc = sqlite3Fts5TermsetAdd(pTermset, 0, pToken, nToken, &bPresent);
+  if( rc==SQLITE_OK && bPresent==0 ){
+    pCtx->cksum ^= sqlite3Fts5IndexEntryCksum(
+        pCtx->iRowid, iCol, iPos, 0, pToken, nToken
+    );
+  }
+
+  for(ii=0; rc==SQLITE_OK && ii<pCtx->pConfig->nPrefix; ii++){
+    const int nChar = pCtx->pConfig->aPrefix[ii];
+    int nByte = sqlite3Fts5IndexCharlenToBytelen(pToken, nToken, nChar);
+    if( nByte ){
+      rc = sqlite3Fts5TermsetAdd(pTermset, ii+1, pToken, nByte, &bPresent);
+      if( bPresent==0 ){
+        pCtx->cksum ^= sqlite3Fts5IndexEntryCksum(
+            pCtx->iRowid, iCol, iPos, ii+1, pToken, nByte
+        );
+      }
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Check that the contents of the FTS index match that of the %_content
+** table. Return SQLITE_OK if they do, or SQLITE_CORRUPT if not. Return
+** some other SQLite error code if an error occurs while attempting to
+** determine this.
+*/
+static int sqlite3Fts5StorageIntegrity(Fts5Storage *p){
+  Fts5Config *pConfig = p->pConfig;
+  int rc;                         /* Return code */
+  int *aColSize;                  /* Array of size pConfig->nCol */
+  i64 *aTotalSize;                /* Array of size pConfig->nCol */
+  Fts5IntegrityCtx ctx;
+  sqlite3_stmt *pScan;
+
+  memset(&ctx, 0, sizeof(Fts5IntegrityCtx));
+  ctx.pConfig = p->pConfig;
+  aTotalSize = (i64*)sqlite3_malloc(pConfig->nCol * (sizeof(int)+sizeof(i64)));
+  if( !aTotalSize ) return SQLITE_NOMEM;
+  aColSize = (int*)&aTotalSize[pConfig->nCol];
+  memset(aTotalSize, 0, sizeof(i64) * pConfig->nCol);
+
+  /* Generate the expected index checksum based on the contents of the
+  ** %_content table. This block stores the checksum in ctx.cksum. */
+  rc = fts5StorageGetStmt(p, FTS5_STMT_SCAN, &pScan, 0);
+  if( rc==SQLITE_OK ){
+    int rc2;
+    while( SQLITE_ROW==sqlite3_step(pScan) ){
+      int i;
+      ctx.iRowid = sqlite3_column_int64(pScan, 0);
+      ctx.szCol = 0;
+      if( pConfig->bColumnsize ){
+        rc = sqlite3Fts5StorageDocsize(p, ctx.iRowid, aColSize);
+      }
+      if( rc==SQLITE_OK && pConfig->eDetail==FTS5_DETAIL_NONE ){
+        rc = sqlite3Fts5TermsetNew(&ctx.pTermset);
+      }
+      for(i=0; rc==SQLITE_OK && i<pConfig->nCol; i++){
+        if( pConfig->abUnindexed[i] ) continue;
+        ctx.iCol = i;
+        ctx.szCol = 0;
+        if( pConfig->eDetail==FTS5_DETAIL_COLUMNS ){
+          rc = sqlite3Fts5TermsetNew(&ctx.pTermset);
+        }
+        if( rc==SQLITE_OK ){
+          rc = sqlite3Fts5Tokenize(pConfig, 
+              FTS5_TOKENIZE_DOCUMENT,
+              (const char*)sqlite3_column_text(pScan, i+1),
+              sqlite3_column_bytes(pScan, i+1),
+              (void*)&ctx,
+              fts5StorageIntegrityCallback
+          );
+        }
+        if( rc==SQLITE_OK && pConfig->bColumnsize && ctx.szCol!=aColSize[i] ){
+          rc = FTS5_CORRUPT;
+        }
+        aTotalSize[i] += ctx.szCol;
+        if( pConfig->eDetail==FTS5_DETAIL_COLUMNS ){
+          sqlite3Fts5TermsetFree(ctx.pTermset);
+          ctx.pTermset = 0;
+        }
+      }
+      sqlite3Fts5TermsetFree(ctx.pTermset);
+      ctx.pTermset = 0;
+
+      if( rc!=SQLITE_OK ) break;
+    }
+    rc2 = sqlite3_reset(pScan);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }
+
+  /* Test that the "totals" (sometimes called "averages") record looks Ok */
+  if( rc==SQLITE_OK ){
+    int i;
+    rc = fts5StorageLoadTotals(p, 0);
+    for(i=0; rc==SQLITE_OK && i<pConfig->nCol; i++){
+      if( p->aTotalSize[i]!=aTotalSize[i] ) rc = FTS5_CORRUPT;
+    }
+  }
+
+  /* Check that the %_docsize and %_content tables contain the expected
+  ** number of rows.  */
+  if( rc==SQLITE_OK && pConfig->eContent==FTS5_CONTENT_NORMAL ){
+    i64 nRow = 0;
+    rc = fts5StorageCount(p, "content", &nRow);
+    if( rc==SQLITE_OK && nRow!=p->nTotalRow ) rc = FTS5_CORRUPT;
+  }
+  if( rc==SQLITE_OK && pConfig->bColumnsize ){
+    i64 nRow = 0;
+    rc = fts5StorageCount(p, "docsize", &nRow);
+    if( rc==SQLITE_OK && nRow!=p->nTotalRow ) rc = FTS5_CORRUPT;
+  }
+
+  /* Pass the expected checksum down to the FTS index module. It will
+  ** verify, amongst other things, that it matches the checksum generated by
+  ** inspecting the index itself.  */
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts5IndexIntegrityCheck(p->pIndex, ctx.cksum);
+  }
+
+  sqlite3_free(aTotalSize);
+  return rc;
+}
+
+/*
+** Obtain an SQLite statement handle that may be used to read data from the
+** %_content table.
+*/
+static int sqlite3Fts5StorageStmt(
+  Fts5Storage *p, 
+  int eStmt, 
+  sqlite3_stmt **pp, 
+  char **pzErrMsg
+){
+  int rc;
+  assert( eStmt==FTS5_STMT_SCAN_ASC 
+       || eStmt==FTS5_STMT_SCAN_DESC
+       || eStmt==FTS5_STMT_LOOKUP
+  );
+  rc = fts5StorageGetStmt(p, eStmt, pp, pzErrMsg);
+  if( rc==SQLITE_OK ){
+    assert( p->aStmt[eStmt]==*pp );
+    p->aStmt[eStmt] = 0;
+  }
+  return rc;
+}
+
+/*
+** Release an SQLite statement handle obtained via an earlier call to
+** sqlite3Fts5StorageStmt(). The eStmt parameter passed to this function
+** must match that passed to the sqlite3Fts5StorageStmt() call.
+*/
+static void sqlite3Fts5StorageStmtRelease(
+  Fts5Storage *p, 
+  int eStmt, 
+  sqlite3_stmt *pStmt
+){
+  assert( eStmt==FTS5_STMT_SCAN_ASC
+       || eStmt==FTS5_STMT_SCAN_DESC
+       || eStmt==FTS5_STMT_LOOKUP
+  );
+  if( p->aStmt[eStmt]==0 ){
+    sqlite3_reset(pStmt);
+    p->aStmt[eStmt] = pStmt;
+  }else{
+    sqlite3_finalize(pStmt);
+  }
+}
+
+static int fts5StorageDecodeSizeArray(
+  int *aCol, int nCol,            /* Array to populate */
+  const u8 *aBlob, int nBlob      /* Record to read varints from */
+){
+  int i;
+  int iOff = 0;
+  for(i=0; i<nCol; i++){
+    if( iOff>=nBlob ) return 1;
+    iOff += fts5GetVarint32(&aBlob[iOff], aCol[i]);
+  }
+  return (iOff!=nBlob);
+}
+
+/*
+** Argument aCol points to an array of integers containing one entry for
+** each table column. This function reads the %_docsize record for the
+** specified rowid and populates aCol[] with the results.
+**
+** An SQLite error code is returned if an error occurs, or SQLITE_OK
+** otherwise.
+*/
+static int sqlite3Fts5StorageDocsize(Fts5Storage *p, i64 iRowid, int *aCol){
+  int nCol = p->pConfig->nCol;    /* Number of user columns in table */
+  sqlite3_stmt *pLookup = 0;      /* Statement to query %_docsize */
+  int rc;                         /* Return Code */
+
+  assert( p->pConfig->bColumnsize );
+  rc = fts5StorageGetStmt(p, FTS5_STMT_LOOKUP_DOCSIZE, &pLookup, 0);
+  if( rc==SQLITE_OK ){
+    int bCorrupt = 1;
+    sqlite3_bind_int64(pLookup, 1, iRowid);
+    if( SQLITE_ROW==sqlite3_step(pLookup) ){
+      const u8 *aBlob = sqlite3_column_blob(pLookup, 0);
+      int nBlob = sqlite3_column_bytes(pLookup, 0);
+      if( 0==fts5StorageDecodeSizeArray(aCol, nCol, aBlob, nBlob) ){
+        bCorrupt = 0;
+      }
+    }
+    rc = sqlite3_reset(pLookup);
+    if( bCorrupt && rc==SQLITE_OK ){
+      rc = FTS5_CORRUPT;
+    }
+  }
+
+  return rc;
+}
+
+static int sqlite3Fts5StorageSize(Fts5Storage *p, int iCol, i64 *pnToken){
+  int rc = fts5StorageLoadTotals(p, 0);
+  if( rc==SQLITE_OK ){
+    *pnToken = 0;
+    if( iCol<0 ){
+      int i;
+      for(i=0; i<p->pConfig->nCol; i++){
+        *pnToken += p->aTotalSize[i];
+      }
+    }else if( iCol<p->pConfig->nCol ){
+      *pnToken = p->aTotalSize[iCol];
+    }else{
+      rc = SQLITE_RANGE;
+    }
+  }
+  return rc;
+}
+
+static int sqlite3Fts5StorageRowCount(Fts5Storage *p, i64 *pnRow){
+  int rc = fts5StorageLoadTotals(p, 0);
+  if( rc==SQLITE_OK ){
+    *pnRow = p->nTotalRow;
+  }
+  return rc;
+}
+
+/*
+** Flush any data currently held in-memory to disk.
+*/
+static int sqlite3Fts5StorageSync(Fts5Storage *p, int bCommit){
+  if( bCommit && p->bTotalsValid ){
+    int rc = fts5StorageSaveTotals(p);
+    p->bTotalsValid = 0;
+    if( rc!=SQLITE_OK ) return rc;
+  }
+  return sqlite3Fts5IndexSync(p->pIndex, bCommit);
+}
+
+static int sqlite3Fts5StorageRollback(Fts5Storage *p){
+  p->bTotalsValid = 0;
+  return sqlite3Fts5IndexRollback(p->pIndex);
+}
+
+static int sqlite3Fts5StorageConfigValue(
+  Fts5Storage *p, 
+  const char *z,
+  sqlite3_value *pVal,
+  int iVal
+){
+  sqlite3_stmt *pReplace = 0;
+  int rc = fts5StorageGetStmt(p, FTS5_STMT_REPLACE_CONFIG, &pReplace, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_text(pReplace, 1, z, -1, SQLITE_STATIC);
+    if( pVal ){
+      sqlite3_bind_value(pReplace, 2, pVal);
+    }else{
+      sqlite3_bind_int(pReplace, 2, iVal);
+    }
+    sqlite3_step(pReplace);
+    rc = sqlite3_reset(pReplace);
+  }
+  if( rc==SQLITE_OK && pVal ){
+    int iNew = p->pConfig->iCookie + 1;
+    rc = sqlite3Fts5IndexSetCookie(p->pIndex, iNew);
+    if( rc==SQLITE_OK ){
+      p->pConfig->iCookie = iNew;
+    }
+  }
+  return rc;
+}
+
+/*
+** 2014 May 31
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+*/
+
+
+/* #include "fts5Int.h" */
+
+/**************************************************************************
+** Start of ascii tokenizer implementation.
+*/
+
+/*
+** For tokenizers with no "unicode" modifier, the set of token characters
+** is the same as the set of ASCII range alphanumeric characters. 
+*/
+static unsigned char aAsciiTokenChar[128] = {
+  0, 0, 0, 0, 0, 0, 0, 0,   0, 0, 0, 0, 0, 0, 0, 0,   /* 0x00..0x0F */
+  0, 0, 0, 0, 0, 0, 0, 0,   0, 0, 0, 0, 0, 0, 0, 0,   /* 0x10..0x1F */
+  0, 0, 0, 0, 0, 0, 0, 0,   0, 0, 0, 0, 0, 0, 0, 0,   /* 0x20..0x2F */
+  1, 1, 1, 1, 1, 1, 1, 1,   1, 1, 0, 0, 0, 0, 0, 0,   /* 0x30..0x3F */
+  0, 1, 1, 1, 1, 1, 1, 1,   1, 1, 1, 1, 1, 1, 1, 1,   /* 0x40..0x4F */
+  1, 1, 1, 1, 1, 1, 1, 1,   1, 1, 1, 0, 0, 0, 0, 0,   /* 0x50..0x5F */
+  0, 1, 1, 1, 1, 1, 1, 1,   1, 1, 1, 1, 1, 1, 1, 1,   /* 0x60..0x6F */
+  1, 1, 1, 1, 1, 1, 1, 1,   1, 1, 1, 0, 0, 0, 0, 0,   /* 0x70..0x7F */
+};
+
+typedef struct AsciiTokenizer AsciiTokenizer;
+struct AsciiTokenizer {
+  unsigned char aTokenChar[128];
+};
+
+static void fts5AsciiAddExceptions(
+  AsciiTokenizer *p, 
+  const char *zArg, 
+  int bTokenChars
+){
+  int i;
+  for(i=0; zArg[i]; i++){
+    if( (zArg[i] & 0x80)==0 ){
+      p->aTokenChar[(int)zArg[i]] = (unsigned char)bTokenChars;
+    }
+  }
+}
+
+/*
+** Delete a "ascii" tokenizer.
+*/
+static void fts5AsciiDelete(Fts5Tokenizer *p){
+  sqlite3_free(p);
+}
+
+/*
+** Create an "ascii" tokenizer.
+*/
+static int fts5AsciiCreate(
+  void *pUnused, 
+  const char **azArg, int nArg,
+  Fts5Tokenizer **ppOut
+){
+  int rc = SQLITE_OK;
+  AsciiTokenizer *p = 0;
+  UNUSED_PARAM(pUnused);
+  if( nArg%2 ){
+    rc = SQLITE_ERROR;
+  }else{
+    p = sqlite3_malloc(sizeof(AsciiTokenizer));
+    if( p==0 ){
+      rc = SQLITE_NOMEM;
+    }else{
+      int i;
+      memset(p, 0, sizeof(AsciiTokenizer));
+      memcpy(p->aTokenChar, aAsciiTokenChar, sizeof(aAsciiTokenChar));
+      for(i=0; rc==SQLITE_OK && i<nArg; i+=2){
+        const char *zArg = azArg[i+1];
+        if( 0==sqlite3_stricmp(azArg[i], "tokenchars") ){
+          fts5AsciiAddExceptions(p, zArg, 1);
+        }else
+        if( 0==sqlite3_stricmp(azArg[i], "separators") ){
+          fts5AsciiAddExceptions(p, zArg, 0);
+        }else{
+          rc = SQLITE_ERROR;
+        }
+      }
+      if( rc!=SQLITE_OK ){
+        fts5AsciiDelete((Fts5Tokenizer*)p);
+        p = 0;
+      }
+    }
+  }
+
+  *ppOut = (Fts5Tokenizer*)p;
+  return rc;
+}
+
+
+static void asciiFold(char *aOut, const char *aIn, int nByte){
+  int i;
+  for(i=0; i<nByte; i++){
+    char c = aIn[i];
+    if( c>='A' && c<='Z' ) c += 32;
+    aOut[i] = c;
+  }
+}
+
+/*
+** Tokenize some text using the ascii tokenizer.
+*/
+static int fts5AsciiTokenize(
+  Fts5Tokenizer *pTokenizer,
+  void *pCtx,
+  int iUnused,
+  const char *pText, int nText,
+  int (*xToken)(void*, int, const char*, int nToken, int iStart, int iEnd)
+){
+  AsciiTokenizer *p = (AsciiTokenizer*)pTokenizer;
+  int rc = SQLITE_OK;
+  int ie;
+  int is = 0;
+
+  char aFold[64];
+  int nFold = sizeof(aFold);
+  char *pFold = aFold;
+  unsigned char *a = p->aTokenChar;
+
+  UNUSED_PARAM(iUnused);
+
+  while( is<nText && rc==SQLITE_OK ){
+    int nByte;
+
+    /* Skip any leading divider characters. */
+    while( is<nText && ((pText[is]&0x80)==0 && a[(int)pText[is]]==0) ){
+      is++;
+    }
+    if( is==nText ) break;
+
+    /* Count the token characters */
+    ie = is+1;
+    while( ie<nText && ((pText[ie]&0x80) || a[(int)pText[ie]] ) ){
+      ie++;
+    }
+
+    /* Fold to lower case */
+    nByte = ie-is;
+    if( nByte>nFold ){
+      if( pFold!=aFold ) sqlite3_free(pFold);
+      pFold = sqlite3_malloc(nByte*2);
+      if( pFold==0 ){
+        rc = SQLITE_NOMEM;
+        break;
+      }
+      nFold = nByte*2;
+    }
+    asciiFold(pFold, &pText[is], nByte);
+
+    /* Invoke the token callback */
+    rc = xToken(pCtx, 0, pFold, nByte, is, ie);
+    is = ie+1;
+  }
+  
+  if( pFold!=aFold ) sqlite3_free(pFold);
+  if( rc==SQLITE_DONE ) rc = SQLITE_OK;
+  return rc;
+}
+
+/**************************************************************************
+** Start of unicode61 tokenizer implementation.
+*/
+
+
+/*
+** The following two macros - READ_UTF8 and WRITE_UTF8 - have been copied
+** from the sqlite3 source file utf.c. If this file is compiled as part
+** of the amalgamation, they are not required.
+*/
+#ifndef SQLITE_AMALGAMATION
+
+static const unsigned char sqlite3Utf8Trans1[] = {
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+  0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+  0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x00, 0x01, 0x02, 0x03, 0x00, 0x01, 0x00, 0x00,
+};
+
+#define READ_UTF8(zIn, zTerm, c)                           \
+  c = *(zIn++);                                            \
+  if( c>=0xc0 ){                                           \
+    c = sqlite3Utf8Trans1[c-0xc0];                         \
+    while( zIn!=zTerm && (*zIn & 0xc0)==0x80 ){            \
+      c = (c<<6) + (0x3f & *(zIn++));                      \
+    }                                                      \
+    if( c<0x80                                             \
+        || (c&0xFFFFF800)==0xD800                          \
+        || (c&0xFFFFFFFE)==0xFFFE ){  c = 0xFFFD; }        \
+  }
+
+
+#define WRITE_UTF8(zOut, c) {                          \
+  if( c<0x00080 ){                                     \
+    *zOut++ = (unsigned char)(c&0xFF);                 \
+  }                                                    \
+  else if( c<0x00800 ){                                \
+    *zOut++ = 0xC0 + (unsigned char)((c>>6)&0x1F);     \
+    *zOut++ = 0x80 + (unsigned char)(c & 0x3F);        \
+  }                                                    \
+  else if( c<0x10000 ){                                \
+    *zOut++ = 0xE0 + (unsigned char)((c>>12)&0x0F);    \
+    *zOut++ = 0x80 + (unsigned char)((c>>6) & 0x3F);   \
+    *zOut++ = 0x80 + (unsigned char)(c & 0x3F);        \
+  }else{                                               \
+    *zOut++ = 0xF0 + (unsigned char)((c>>18) & 0x07);  \
+    *zOut++ = 0x80 + (unsigned char)((c>>12) & 0x3F);  \
+    *zOut++ = 0x80 + (unsigned char)((c>>6) & 0x3F);   \
+    *zOut++ = 0x80 + (unsigned char)(c & 0x3F);        \
+  }                                                    \
+}
+
+#endif /* ifndef SQLITE_AMALGAMATION */
+
+typedef struct Unicode61Tokenizer Unicode61Tokenizer;
+struct Unicode61Tokenizer {
+  unsigned char aTokenChar[128];  /* ASCII range token characters */
+  char *aFold;                    /* Buffer to fold text into */
+  int nFold;                      /* Size of aFold[] in bytes */
+  int bRemoveDiacritic;           /* True if remove_diacritics=1 is set */
+  int nException;
+  int *aiException;
+};
+
+static int fts5UnicodeAddExceptions(
+  Unicode61Tokenizer *p,          /* Tokenizer object */
+  const char *z,                  /* Characters to treat as exceptions */
+  int bTokenChars                 /* 1 for 'tokenchars', 0 for 'separators' */
+){
+  int rc = SQLITE_OK;
+  int n = (int)strlen(z);
+  int *aNew;
+
+  if( n>0 ){
+    aNew = (int*)sqlite3_realloc(p->aiException, (n+p->nException)*sizeof(int));
+    if( aNew ){
+      int nNew = p->nException;
+      const unsigned char *zCsr = (const unsigned char*)z;
+      const unsigned char *zTerm = (const unsigned char*)&z[n];
+      while( zCsr<zTerm ){
+        int iCode;
+        int bToken;
+        READ_UTF8(zCsr, zTerm, iCode);
+        if( iCode<128 ){
+          p->aTokenChar[iCode] = (unsigned char)bTokenChars;
+        }else{
+          bToken = sqlite3Fts5UnicodeIsalnum(iCode);
+          assert( (bToken==0 || bToken==1) ); 
+          assert( (bTokenChars==0 || bTokenChars==1) );
+          if( bToken!=bTokenChars && sqlite3Fts5UnicodeIsdiacritic(iCode)==0 ){
+            int i;
+            for(i=0; i<nNew; i++){
+              if( aNew[i]>iCode ) break;
+            }
+            memmove(&aNew[i+1], &aNew[i], (nNew-i)*sizeof(int));
+            aNew[i] = iCode;
+            nNew++;
+          }
+        }
+      }
+      p->aiException = aNew;
+      p->nException = nNew;
+    }else{
+      rc = SQLITE_NOMEM;
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Return true if the p->aiException[] array contains the value iCode.
+*/
+static int fts5UnicodeIsException(Unicode61Tokenizer *p, int iCode){
+  if( p->nException>0 ){
+    int *a = p->aiException;
+    int iLo = 0;
+    int iHi = p->nException-1;
+
+    while( iHi>=iLo ){
+      int iTest = (iHi + iLo) / 2;
+      if( iCode==a[iTest] ){
+        return 1;
+      }else if( iCode>a[iTest] ){
+        iLo = iTest+1;
+      }else{
+        iHi = iTest-1;
+      }
+    }
+  }
+
+  return 0;
+}
+
+/*
+** Delete a "unicode61" tokenizer.
+*/
+static void fts5UnicodeDelete(Fts5Tokenizer *pTok){
+  if( pTok ){
+    Unicode61Tokenizer *p = (Unicode61Tokenizer*)pTok;
+    sqlite3_free(p->aiException);
+    sqlite3_free(p->aFold);
+    sqlite3_free(p);
+  }
+  return;
+}
+
+/*
+** Create a "unicode61" tokenizer.
+*/
+static int fts5UnicodeCreate(
+  void *pUnused, 
+  const char **azArg, int nArg,
+  Fts5Tokenizer **ppOut
+){
+  int rc = SQLITE_OK;             /* Return code */
+  Unicode61Tokenizer *p = 0;      /* New tokenizer object */ 
+
+  UNUSED_PARAM(pUnused);
+
+  if( nArg%2 ){
+    rc = SQLITE_ERROR;
+  }else{
+    p = (Unicode61Tokenizer*)sqlite3_malloc(sizeof(Unicode61Tokenizer));
+    if( p ){
+      int i;
+      memset(p, 0, sizeof(Unicode61Tokenizer));
+      memcpy(p->aTokenChar, aAsciiTokenChar, sizeof(aAsciiTokenChar));
+      p->bRemoveDiacritic = 1;
+      p->nFold = 64;
+      p->aFold = sqlite3_malloc(p->nFold * sizeof(char));
+      if( p->aFold==0 ){
+        rc = SQLITE_NOMEM;
+      }
+      for(i=0; rc==SQLITE_OK && i<nArg; i+=2){
+        const char *zArg = azArg[i+1];
+        if( 0==sqlite3_stricmp(azArg[i], "remove_diacritics") ){
+          if( (zArg[0]!='0' && zArg[0]!='1') || zArg[1] ){
+            rc = SQLITE_ERROR;
+          }
+          p->bRemoveDiacritic = (zArg[0]=='1');
+        }else
+        if( 0==sqlite3_stricmp(azArg[i], "tokenchars") ){
+          rc = fts5UnicodeAddExceptions(p, zArg, 1);
+        }else
+        if( 0==sqlite3_stricmp(azArg[i], "separators") ){
+          rc = fts5UnicodeAddExceptions(p, zArg, 0);
+        }else{
+          rc = SQLITE_ERROR;
+        }
+      }
+    }else{
+      rc = SQLITE_NOMEM;
+    }
+    if( rc!=SQLITE_OK ){
+      fts5UnicodeDelete((Fts5Tokenizer*)p);
+      p = 0;
+    }
+    *ppOut = (Fts5Tokenizer*)p;
+  }
+  return rc;
+}
+
+/*
+** Return true if, for the purposes of tokenizing with the tokenizer
+** passed as the first argument, codepoint iCode is considered a token 
+** character (not a separator).
+*/
+static int fts5UnicodeIsAlnum(Unicode61Tokenizer *p, int iCode){
+  assert( (sqlite3Fts5UnicodeIsalnum(iCode) & 0xFFFFFFFE)==0 );
+  return sqlite3Fts5UnicodeIsalnum(iCode) ^ fts5UnicodeIsException(p, iCode);
+}
+
+static int fts5UnicodeTokenize(
+  Fts5Tokenizer *pTokenizer,
+  void *pCtx,
+  int iUnused,
+  const char *pText, int nText,
+  int (*xToken)(void*, int, const char*, int nToken, int iStart, int iEnd)
+){
+  Unicode61Tokenizer *p = (Unicode61Tokenizer*)pTokenizer;
+  int rc = SQLITE_OK;
+  unsigned char *a = p->aTokenChar;
+
+  unsigned char *zTerm = (unsigned char*)&pText[nText];
+  unsigned char *zCsr = (unsigned char *)pText;
+
+  /* Output buffer */
+  char *aFold = p->aFold;
+  int nFold = p->nFold;
+  const char *pEnd = &aFold[nFold-6];
+
+  UNUSED_PARAM(iUnused);
+
+  /* Each iteration of this loop gobbles up a contiguous run of separators,
+  ** then the next token.  */
+  while( rc==SQLITE_OK ){
+    int iCode;                    /* non-ASCII codepoint read from input */
+    char *zOut = aFold;
+    int is;
+    int ie;
+
+    /* Skip any separator characters. */
+    while( 1 ){
+      if( zCsr>=zTerm ) goto tokenize_done;
+      if( *zCsr & 0x80 ) {
+        /* A character outside of the ascii range. Skip past it if it is
+        ** a separator character. Or break out of the loop if it is not. */
+        is = zCsr - (unsigned char*)pText;
+        READ_UTF8(zCsr, zTerm, iCode);
+        if( fts5UnicodeIsAlnum(p, iCode) ){
+          goto non_ascii_tokenchar;
+        }
+      }else{
+        if( a[*zCsr] ){
+          is = zCsr - (unsigned char*)pText;
+          goto ascii_tokenchar;
+        }
+        zCsr++;
+      }
+    }
+
+    /* Run through the tokenchars. Fold them into the output buffer along
+    ** the way.  */
+    while( zCsr<zTerm ){
+
+      /* Grow the output buffer so that there is sufficient space to fit the
+      ** largest possible utf-8 character.  */
+      if( zOut>pEnd ){
+        aFold = sqlite3_malloc(nFold*2);
+        if( aFold==0 ){
+          rc = SQLITE_NOMEM;
+          goto tokenize_done;
+        }
+        zOut = &aFold[zOut - p->aFold];
+        memcpy(aFold, p->aFold, nFold);
+        sqlite3_free(p->aFold);
+        p->aFold = aFold;
+        p->nFold = nFold = nFold*2;
+        pEnd = &aFold[nFold-6];
+      }
+
+      if( *zCsr & 0x80 ){
+        /* An non-ascii-range character. Fold it into the output buffer if
+        ** it is a token character, or break out of the loop if it is not. */
+        READ_UTF8(zCsr, zTerm, iCode);
+        if( fts5UnicodeIsAlnum(p,iCode)||sqlite3Fts5UnicodeIsdiacritic(iCode) ){
+ non_ascii_tokenchar:
+          iCode = sqlite3Fts5UnicodeFold(iCode, p->bRemoveDiacritic);
+          if( iCode ) WRITE_UTF8(zOut, iCode);
+        }else{
+          break;
+        }
+      }else if( a[*zCsr]==0 ){
+        /* An ascii-range separator character. End of token. */
+        break; 
+      }else{
+ ascii_tokenchar:
+        if( *zCsr>='A' && *zCsr<='Z' ){
+          *zOut++ = *zCsr + 32;
+        }else{
+          *zOut++ = *zCsr;
+        }
+        zCsr++;
+      }
+      ie = zCsr - (unsigned char*)pText;
+    }
+
+    /* Invoke the token callback */
+    rc = xToken(pCtx, 0, aFold, zOut-aFold, is, ie); 
+  }
+  
+ tokenize_done:
+  if( rc==SQLITE_DONE ) rc = SQLITE_OK;
+  return rc;
+}
+
+/**************************************************************************
+** Start of porter stemmer implementation.
+*/
+
+/* Any tokens larger than this (in bytes) are passed through without
+** stemming. */
+#define FTS5_PORTER_MAX_TOKEN 64
+
+typedef struct PorterTokenizer PorterTokenizer;
+struct PorterTokenizer {
+  fts5_tokenizer tokenizer;       /* Parent tokenizer module */
+  Fts5Tokenizer *pTokenizer;      /* Parent tokenizer instance */
+  char aBuf[FTS5_PORTER_MAX_TOKEN + 64];
+};
+
+/*
+** Delete a "porter" tokenizer.
+*/
+static void fts5PorterDelete(Fts5Tokenizer *pTok){
+  if( pTok ){
+    PorterTokenizer *p = (PorterTokenizer*)pTok;
+    if( p->pTokenizer ){
+      p->tokenizer.xDelete(p->pTokenizer);
+    }
+    sqlite3_free(p);
+  }
+}
+
+/*
+** Create a "porter" tokenizer.
+*/
+static int fts5PorterCreate(
+  void *pCtx, 
+  const char **azArg, int nArg,
+  Fts5Tokenizer **ppOut
+){
+  fts5_api *pApi = (fts5_api*)pCtx;
+  int rc = SQLITE_OK;
+  PorterTokenizer *pRet;
+  void *pUserdata = 0;
+  const char *zBase = "unicode61";
+
+  if( nArg>0 ){
+    zBase = azArg[0];
+  }
+
+  pRet = (PorterTokenizer*)sqlite3_malloc(sizeof(PorterTokenizer));
+  if( pRet ){
+    memset(pRet, 0, sizeof(PorterTokenizer));
+    rc = pApi->xFindTokenizer(pApi, zBase, &pUserdata, &pRet->tokenizer);
+  }else{
+    rc = SQLITE_NOMEM;
+  }
+  if( rc==SQLITE_OK ){
+    int nArg2 = (nArg>0 ? nArg-1 : 0);
+    const char **azArg2 = (nArg2 ? &azArg[1] : 0);
+    rc = pRet->tokenizer.xCreate(pUserdata, azArg2, nArg2, &pRet->pTokenizer);
+  }
+
+  if( rc!=SQLITE_OK ){
+    fts5PorterDelete((Fts5Tokenizer*)pRet);
+    pRet = 0;
+  }
+  *ppOut = (Fts5Tokenizer*)pRet;
+  return rc;
+}
+
+typedef struct PorterContext PorterContext;
+struct PorterContext {
+  void *pCtx;
+  int (*xToken)(void*, int, const char*, int, int, int);
+  char *aBuf;
+};
+
+typedef struct PorterRule PorterRule;
+struct PorterRule {
+  const char *zSuffix;
+  int nSuffix;
+  int (*xCond)(char *zStem, int nStem);
+  const char *zOutput;
+  int nOutput;
+};
+
+#if 0
+static int fts5PorterApply(char *aBuf, int *pnBuf, PorterRule *aRule){
+  int ret = -1;
+  int nBuf = *pnBuf;
+  PorterRule *p;
+
+  for(p=aRule; p->zSuffix; p++){
+    assert( strlen(p->zSuffix)==p->nSuffix );
+    assert( strlen(p->zOutput)==p->nOutput );
+    if( nBuf<p->nSuffix ) continue;
+    if( 0==memcmp(&aBuf[nBuf - p->nSuffix], p->zSuffix, p->nSuffix) ) break;
+  }
+
+  if( p->zSuffix ){
+    int nStem = nBuf - p->nSuffix;
+    if( p->xCond==0 || p->xCond(aBuf, nStem) ){
+      memcpy(&aBuf[nStem], p->zOutput, p->nOutput);
+      *pnBuf = nStem + p->nOutput;
+      ret = p - aRule;
+    }
+  }
+
+  return ret;
+}
+#endif
+
+static int fts5PorterIsVowel(char c, int bYIsVowel){
+  return (
+      c=='a' || c=='e' || c=='i' || c=='o' || c=='u' || (bYIsVowel && c=='y')
+  );
+}
+
+static int fts5PorterGobbleVC(char *zStem, int nStem, int bPrevCons){
+  int i;
+  int bCons = bPrevCons;
+
+  /* Scan for a vowel */
+  for(i=0; i<nStem; i++){
+    if( 0==(bCons = !fts5PorterIsVowel(zStem[i], bCons)) ) break;
+  }
+
+  /* Scan for a consonent */
+  for(i++; i<nStem; i++){
+    if( (bCons = !fts5PorterIsVowel(zStem[i], bCons)) ) return i+1;
+  }
+  return 0;
+}
+
+/* porter rule condition: (m > 0) */
+static int fts5Porter_MGt0(char *zStem, int nStem){
+  return !!fts5PorterGobbleVC(zStem, nStem, 0);
+}
+
+/* porter rule condition: (m > 1) */
+static int fts5Porter_MGt1(char *zStem, int nStem){
+  int n;
+  n = fts5PorterGobbleVC(zStem, nStem, 0);
+  if( n && fts5PorterGobbleVC(&zStem[n], nStem-n, 1) ){
+    return 1;
+  }
+  return 0;
+}
+
+/* porter rule condition: (m = 1) */
+static int fts5Porter_MEq1(char *zStem, int nStem){
+  int n;
+  n = fts5PorterGobbleVC(zStem, nStem, 0);
+  if( n && 0==fts5PorterGobbleVC(&zStem[n], nStem-n, 1) ){
+    return 1;
+  }
+  return 0;
+}
+
+/* porter rule condition: (*o) */
+static int fts5Porter_Ostar(char *zStem, int nStem){
+  if( zStem[nStem-1]=='w' || zStem[nStem-1]=='x' || zStem[nStem-1]=='y' ){
+    return 0;
+  }else{
+    int i;
+    int mask = 0;
+    int bCons = 0;
+    for(i=0; i<nStem; i++){
+      bCons = !fts5PorterIsVowel(zStem[i], bCons);
+      assert( bCons==0 || bCons==1 );
+      mask = (mask << 1) + bCons;
+    }
+    return ((mask & 0x0007)==0x0005);
+  }
+}
+
+/* porter rule condition: (m > 1 and (*S or *T)) */
+static int fts5Porter_MGt1_and_S_or_T(char *zStem, int nStem){
+  assert( nStem>0 );
+  return (zStem[nStem-1]=='s' || zStem[nStem-1]=='t') 
+      && fts5Porter_MGt1(zStem, nStem);
+}
+
+/* porter rule condition: (*v*) */
+static int fts5Porter_Vowel(char *zStem, int nStem){
+  int i;
+  for(i=0; i<nStem; i++){
+    if( fts5PorterIsVowel(zStem[i], i>0) ){
+      return 1;
+    }
+  }
+  return 0;
+}
+
+
+/**************************************************************************
+***************************************************************************
+** GENERATED CODE STARTS HERE (mkportersteps.tcl)
+*/
+
+static int fts5PorterStep4(char *aBuf, int *pnBuf){
+  int ret = 0;
+  int nBuf = *pnBuf;
+  switch( aBuf[nBuf-2] ){
+    
+    case 'a': 
+      if( nBuf>2 && 0==memcmp("al", &aBuf[nBuf-2], 2) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-2) ){
+          *pnBuf = nBuf - 2;
+        }
+      }
+      break;
+  
+    case 'c': 
+      if( nBuf>4 && 0==memcmp("ance", &aBuf[nBuf-4], 4) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-4) ){
+          *pnBuf = nBuf - 4;
+        }
+      }else if( nBuf>4 && 0==memcmp("ence", &aBuf[nBuf-4], 4) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-4) ){
+          *pnBuf = nBuf - 4;
+        }
+      }
+      break;
+  
+    case 'e': 
+      if( nBuf>2 && 0==memcmp("er", &aBuf[nBuf-2], 2) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-2) ){
+          *pnBuf = nBuf - 2;
+        }
+      }
+      break;
+  
+    case 'i': 
+      if( nBuf>2 && 0==memcmp("ic", &aBuf[nBuf-2], 2) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-2) ){
+          *pnBuf = nBuf - 2;
+        }
+      }
+      break;
+  
+    case 'l': 
+      if( nBuf>4 && 0==memcmp("able", &aBuf[nBuf-4], 4) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-4) ){
+          *pnBuf = nBuf - 4;
+        }
+      }else if( nBuf>4 && 0==memcmp("ible", &aBuf[nBuf-4], 4) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-4) ){
+          *pnBuf = nBuf - 4;
+        }
+      }
+      break;
+  
+    case 'n': 
+      if( nBuf>3 && 0==memcmp("ant", &aBuf[nBuf-3], 3) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-3) ){
+          *pnBuf = nBuf - 3;
+        }
+      }else if( nBuf>5 && 0==memcmp("ement", &aBuf[nBuf-5], 5) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-5) ){
+          *pnBuf = nBuf - 5;
+        }
+      }else if( nBuf>4 && 0==memcmp("ment", &aBuf[nBuf-4], 4) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-4) ){
+          *pnBuf = nBuf - 4;
+        }
+      }else if( nBuf>3 && 0==memcmp("ent", &aBuf[nBuf-3], 3) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-3) ){
+          *pnBuf = nBuf - 3;
+        }
+      }
+      break;
+  
+    case 'o': 
+      if( nBuf>3 && 0==memcmp("ion", &aBuf[nBuf-3], 3) ){
+        if( fts5Porter_MGt1_and_S_or_T(aBuf, nBuf-3) ){
+          *pnBuf = nBuf - 3;
+        }
+      }else if( nBuf>2 && 0==memcmp("ou", &aBuf[nBuf-2], 2) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-2) ){
+          *pnBuf = nBuf - 2;
+        }
+      }
+      break;
+  
+    case 's': 
+      if( nBuf>3 && 0==memcmp("ism", &aBuf[nBuf-3], 3) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-3) ){
+          *pnBuf = nBuf - 3;
+        }
+      }
+      break;
+  
+    case 't': 
+      if( nBuf>3 && 0==memcmp("ate", &aBuf[nBuf-3], 3) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-3) ){
+          *pnBuf = nBuf - 3;
+        }
+      }else if( nBuf>3 && 0==memcmp("iti", &aBuf[nBuf-3], 3) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-3) ){
+          *pnBuf = nBuf - 3;
+        }
+      }
+      break;
+  
+    case 'u': 
+      if( nBuf>3 && 0==memcmp("ous", &aBuf[nBuf-3], 3) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-3) ){
+          *pnBuf = nBuf - 3;
+        }
+      }
+      break;
+  
+    case 'v': 
+      if( nBuf>3 && 0==memcmp("ive", &aBuf[nBuf-3], 3) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-3) ){
+          *pnBuf = nBuf - 3;
+        }
+      }
+      break;
+  
+    case 'z': 
+      if( nBuf>3 && 0==memcmp("ize", &aBuf[nBuf-3], 3) ){
+        if( fts5Porter_MGt1(aBuf, nBuf-3) ){
+          *pnBuf = nBuf - 3;
+        }
+      }
+      break;
+  
+  }
+  return ret;
+}
+  
+
+static int fts5PorterStep1B2(char *aBuf, int *pnBuf){
+  int ret = 0;
+  int nBuf = *pnBuf;
+  switch( aBuf[nBuf-2] ){
+    
+    case 'a': 
+      if( nBuf>2 && 0==memcmp("at", &aBuf[nBuf-2], 2) ){
+        memcpy(&aBuf[nBuf-2], "ate", 3);
+        *pnBuf = nBuf - 2 + 3;
+        ret = 1;
+      }
+      break;
+  
+    case 'b': 
+      if( nBuf>2 && 0==memcmp("bl", &aBuf[nBuf-2], 2) ){
+        memcpy(&aBuf[nBuf-2], "ble", 3);
+        *pnBuf = nBuf - 2 + 3;
+        ret = 1;
+      }
+      break;
+  
+    case 'i': 
+      if( nBuf>2 && 0==memcmp("iz", &aBuf[nBuf-2], 2) ){
+        memcpy(&aBuf[nBuf-2], "ize", 3);
+        *pnBuf = nBuf - 2 + 3;
+        ret = 1;
+      }
+      break;
+  
+  }
+  return ret;
+}
+  
+
+static int fts5PorterStep2(char *aBuf, int *pnBuf){
+  int ret = 0;
+  int nBuf = *pnBuf;
+  switch( aBuf[nBuf-2] ){
+    
+    case 'a': 
+      if( nBuf>7 && 0==memcmp("ational", &aBuf[nBuf-7], 7) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-7) ){
+          memcpy(&aBuf[nBuf-7], "ate", 3);
+          *pnBuf = nBuf - 7 + 3;
+        }
+      }else if( nBuf>6 && 0==memcmp("tional", &aBuf[nBuf-6], 6) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-6) ){
+          memcpy(&aBuf[nBuf-6], "tion", 4);
+          *pnBuf = nBuf - 6 + 4;
+        }
+      }
+      break;
+  
+    case 'c': 
+      if( nBuf>4 && 0==memcmp("enci", &aBuf[nBuf-4], 4) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-4) ){
+          memcpy(&aBuf[nBuf-4], "ence", 4);
+          *pnBuf = nBuf - 4 + 4;
+        }
+      }else if( nBuf>4 && 0==memcmp("anci", &aBuf[nBuf-4], 4) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-4) ){
+          memcpy(&aBuf[nBuf-4], "ance", 4);
+          *pnBuf = nBuf - 4 + 4;
+        }
+      }
+      break;
+  
+    case 'e': 
+      if( nBuf>4 && 0==memcmp("izer", &aBuf[nBuf-4], 4) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-4) ){
+          memcpy(&aBuf[nBuf-4], "ize", 3);
+          *pnBuf = nBuf - 4 + 3;
+        }
+      }
+      break;
+  
+    case 'g': 
+      if( nBuf>4 && 0==memcmp("logi", &aBuf[nBuf-4], 4) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-4) ){
+          memcpy(&aBuf[nBuf-4], "log", 3);
+          *pnBuf = nBuf - 4 + 3;
+        }
+      }
+      break;
+  
+    case 'l': 
+      if( nBuf>3 && 0==memcmp("bli", &aBuf[nBuf-3], 3) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-3) ){
+          memcpy(&aBuf[nBuf-3], "ble", 3);
+          *pnBuf = nBuf - 3 + 3;
+        }
+      }else if( nBuf>4 && 0==memcmp("alli", &aBuf[nBuf-4], 4) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-4) ){
+          memcpy(&aBuf[nBuf-4], "al", 2);
+          *pnBuf = nBuf - 4 + 2;
+        }
+      }else if( nBuf>5 && 0==memcmp("entli", &aBuf[nBuf-5], 5) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-5) ){
+          memcpy(&aBuf[nBuf-5], "ent", 3);
+          *pnBuf = nBuf - 5 + 3;
+        }
+      }else if( nBuf>3 && 0==memcmp("eli", &aBuf[nBuf-3], 3) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-3) ){
+          memcpy(&aBuf[nBuf-3], "e", 1);
+          *pnBuf = nBuf - 3 + 1;
+        }
+      }else if( nBuf>5 && 0==memcmp("ousli", &aBuf[nBuf-5], 5) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-5) ){
+          memcpy(&aBuf[nBuf-5], "ous", 3);
+          *pnBuf = nBuf - 5 + 3;
+        }
+      }
+      break;
+  
+    case 'o': 
+      if( nBuf>7 && 0==memcmp("ization", &aBuf[nBuf-7], 7) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-7) ){
+          memcpy(&aBuf[nBuf-7], "ize", 3);
+          *pnBuf = nBuf - 7 + 3;
+        }
+      }else if( nBuf>5 && 0==memcmp("ation", &aBuf[nBuf-5], 5) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-5) ){
+          memcpy(&aBuf[nBuf-5], "ate", 3);
+          *pnBuf = nBuf - 5 + 3;
+        }
+      }else if( nBuf>4 && 0==memcmp("ator", &aBuf[nBuf-4], 4) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-4) ){
+          memcpy(&aBuf[nBuf-4], "ate", 3);
+          *pnBuf = nBuf - 4 + 3;
+        }
+      }
+      break;
+  
+    case 's': 
+      if( nBuf>5 && 0==memcmp("alism", &aBuf[nBuf-5], 5) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-5) ){
+          memcpy(&aBuf[nBuf-5], "al", 2);
+          *pnBuf = nBuf - 5 + 2;
+        }
+      }else if( nBuf>7 && 0==memcmp("iveness", &aBuf[nBuf-7], 7) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-7) ){
+          memcpy(&aBuf[nBuf-7], "ive", 3);
+          *pnBuf = nBuf - 7 + 3;
+        }
+      }else if( nBuf>7 && 0==memcmp("fulness", &aBuf[nBuf-7], 7) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-7) ){
+          memcpy(&aBuf[nBuf-7], "ful", 3);
+          *pnBuf = nBuf - 7 + 3;
+        }
+      }else if( nBuf>7 && 0==memcmp("ousness", &aBuf[nBuf-7], 7) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-7) ){
+          memcpy(&aBuf[nBuf-7], "ous", 3);
+          *pnBuf = nBuf - 7 + 3;
+        }
+      }
+      break;
+  
+    case 't': 
+      if( nBuf>5 && 0==memcmp("aliti", &aBuf[nBuf-5], 5) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-5) ){
+          memcpy(&aBuf[nBuf-5], "al", 2);
+          *pnBuf = nBuf - 5 + 2;
+        }
+      }else if( nBuf>5 && 0==memcmp("iviti", &aBuf[nBuf-5], 5) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-5) ){
+          memcpy(&aBuf[nBuf-5], "ive", 3);
+          *pnBuf = nBuf - 5 + 3;
+        }
+      }else if( nBuf>6 && 0==memcmp("biliti", &aBuf[nBuf-6], 6) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-6) ){
+          memcpy(&aBuf[nBuf-6], "ble", 3);
+          *pnBuf = nBuf - 6 + 3;
+        }
+      }
+      break;
+  
+  }
+  return ret;
+}
+  
+
+static int fts5PorterStep3(char *aBuf, int *pnBuf){
+  int ret = 0;
+  int nBuf = *pnBuf;
+  switch( aBuf[nBuf-2] ){
+    
+    case 'a': 
+      if( nBuf>4 && 0==memcmp("ical", &aBuf[nBuf-4], 4) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-4) ){
+          memcpy(&aBuf[nBuf-4], "ic", 2);
+          *pnBuf = nBuf - 4 + 2;
+        }
+      }
+      break;
+  
+    case 's': 
+      if( nBuf>4 && 0==memcmp("ness", &aBuf[nBuf-4], 4) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-4) ){
+          *pnBuf = nBuf - 4;
+        }
+      }
+      break;
+  
+    case 't': 
+      if( nBuf>5 && 0==memcmp("icate", &aBuf[nBuf-5], 5) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-5) ){
+          memcpy(&aBuf[nBuf-5], "ic", 2);
+          *pnBuf = nBuf - 5 + 2;
+        }
+      }else if( nBuf>5 && 0==memcmp("iciti", &aBuf[nBuf-5], 5) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-5) ){
+          memcpy(&aBuf[nBuf-5], "ic", 2);
+          *pnBuf = nBuf - 5 + 2;
+        }
+      }
+      break;
+  
+    case 'u': 
+      if( nBuf>3 && 0==memcmp("ful", &aBuf[nBuf-3], 3) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-3) ){
+          *pnBuf = nBuf - 3;
+        }
+      }
+      break;
+  
+    case 'v': 
+      if( nBuf>5 && 0==memcmp("ative", &aBuf[nBuf-5], 5) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-5) ){
+          *pnBuf = nBuf - 5;
+        }
+      }
+      break;
+  
+    case 'z': 
+      if( nBuf>5 && 0==memcmp("alize", &aBuf[nBuf-5], 5) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-5) ){
+          memcpy(&aBuf[nBuf-5], "al", 2);
+          *pnBuf = nBuf - 5 + 2;
+        }
+      }
+      break;
+  
+  }
+  return ret;
+}
+  
+
+static int fts5PorterStep1B(char *aBuf, int *pnBuf){
+  int ret = 0;
+  int nBuf = *pnBuf;
+  switch( aBuf[nBuf-2] ){
+    
+    case 'e': 
+      if( nBuf>3 && 0==memcmp("eed", &aBuf[nBuf-3], 3) ){
+        if( fts5Porter_MGt0(aBuf, nBuf-3) ){
+          memcpy(&aBuf[nBuf-3], "ee", 2);
+          *pnBuf = nBuf - 3 + 2;
+        }
+      }else if( nBuf>2 && 0==memcmp("ed", &aBuf[nBuf-2], 2) ){
+        if( fts5Porter_Vowel(aBuf, nBuf-2) ){
+          *pnBuf = nBuf - 2;
+          ret = 1;
+        }
+      }
+      break;
+  
+    case 'n': 
+      if( nBuf>3 && 0==memcmp("ing", &aBuf[nBuf-3], 3) ){
+        if( fts5Porter_Vowel(aBuf, nBuf-3) ){
+          *pnBuf = nBuf - 3;
+          ret = 1;
+        }
+      }
+      break;
+  
+  }
+  return ret;
+}
+  
+/* 
+** GENERATED CODE ENDS HERE (mkportersteps.tcl)
+***************************************************************************
+**************************************************************************/
+
+static void fts5PorterStep1A(char *aBuf, int *pnBuf){
+  int nBuf = *pnBuf;
+  if( aBuf[nBuf-1]=='s' ){
+    if( aBuf[nBuf-2]=='e' ){
+      if( (nBuf>4 && aBuf[nBuf-4]=='s' && aBuf[nBuf-3]=='s') 
+       || (nBuf>3 && aBuf[nBuf-3]=='i' )
+      ){
+        *pnBuf = nBuf-2;
+      }else{
+        *pnBuf = nBuf-1;
+      }
+    }
+    else if( aBuf[nBuf-2]!='s' ){
+      *pnBuf = nBuf-1;
+    }
+  }
+}
+
+static int fts5PorterCb(
+  void *pCtx, 
+  int tflags,
+  const char *pToken, 
+  int nToken, 
+  int iStart, 
+  int iEnd
+){
+  PorterContext *p = (PorterContext*)pCtx;
+
+  char *aBuf;
+  int nBuf;
+
+  if( nToken>FTS5_PORTER_MAX_TOKEN || nToken<3 ) goto pass_through;
+  aBuf = p->aBuf;
+  nBuf = nToken;
+  memcpy(aBuf, pToken, nBuf);
+
+  /* Step 1. */
+  fts5PorterStep1A(aBuf, &nBuf);
+  if( fts5PorterStep1B(aBuf, &nBuf) ){
+    if( fts5PorterStep1B2(aBuf, &nBuf)==0 ){
+      char c = aBuf[nBuf-1];
+      if( fts5PorterIsVowel(c, 0)==0 
+       && c!='l' && c!='s' && c!='z' && c==aBuf[nBuf-2] 
+      ){
+        nBuf--;
+      }else if( fts5Porter_MEq1(aBuf, nBuf) && fts5Porter_Ostar(aBuf, nBuf) ){
+        aBuf[nBuf++] = 'e';
+      }
+    }
+  }
+
+  /* Step 1C. */
+  if( aBuf[nBuf-1]=='y' && fts5Porter_Vowel(aBuf, nBuf-1) ){
+    aBuf[nBuf-1] = 'i';
+  }
+
+  /* Steps 2 through 4. */
+  fts5PorterStep2(aBuf, &nBuf);
+  fts5PorterStep3(aBuf, &nBuf);
+  fts5PorterStep4(aBuf, &nBuf);
+
+  /* Step 5a. */
+  assert( nBuf>0 );
+  if( aBuf[nBuf-1]=='e' ){
+    if( fts5Porter_MGt1(aBuf, nBuf-1) 
+     || (fts5Porter_MEq1(aBuf, nBuf-1) && !fts5Porter_Ostar(aBuf, nBuf-1))
+    ){
+      nBuf--;
+    }
+  }
+
+  /* Step 5b. */
+  if( nBuf>1 && aBuf[nBuf-1]=='l' 
+   && aBuf[nBuf-2]=='l' && fts5Porter_MGt1(aBuf, nBuf-1) 
+  ){
+    nBuf--;
+  }
+
+  return p->xToken(p->pCtx, tflags, aBuf, nBuf, iStart, iEnd);
+
+ pass_through:
+  return p->xToken(p->pCtx, tflags, pToken, nToken, iStart, iEnd);
+}
+
+/*
+** Tokenize using the porter tokenizer.
+*/
+static int fts5PorterTokenize(
+  Fts5Tokenizer *pTokenizer,
+  void *pCtx,
+  int flags,
+  const char *pText, int nText,
+  int (*xToken)(void*, int, const char*, int nToken, int iStart, int iEnd)
+){
+  PorterTokenizer *p = (PorterTokenizer*)pTokenizer;
+  PorterContext sCtx;
+  sCtx.xToken = xToken;
+  sCtx.pCtx = pCtx;
+  sCtx.aBuf = p->aBuf;
+  return p->tokenizer.xTokenize(
+      p->pTokenizer, (void*)&sCtx, flags, pText, nText, fts5PorterCb
+  );
+}
+
+/*
+** Register all built-in tokenizers with FTS5.
+*/
+static int sqlite3Fts5TokenizerInit(fts5_api *pApi){
+  struct BuiltinTokenizer {
+    const char *zName;
+    fts5_tokenizer x;
+  } aBuiltin[] = {
+    { "unicode61", {fts5UnicodeCreate, fts5UnicodeDelete, fts5UnicodeTokenize}},
+    { "ascii",     {fts5AsciiCreate, fts5AsciiDelete, fts5AsciiTokenize }},
+    { "porter",    {fts5PorterCreate, fts5PorterDelete, fts5PorterTokenize }},
+  };
+  
+  int rc = SQLITE_OK;             /* Return code */
+  int i;                          /* To iterate through builtin functions */
+
+  for(i=0; rc==SQLITE_OK && i<ArraySize(aBuiltin); i++){
+    rc = pApi->xCreateTokenizer(pApi,
+        aBuiltin[i].zName,
+        (void*)pApi,
+        &aBuiltin[i].x,
+        0
+    );
+  }
+
+  return rc;
+}
+
+
+
+/*
+** 2012 May 25
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+*/
+
+/*
+** DO NOT EDIT THIS MACHINE GENERATED FILE.
+*/
+
+
+/* #include <assert.h> */
+
+/*
+** Return true if the argument corresponds to a unicode codepoint
+** classified as either a letter or a number. Otherwise false.
+**
+** The results are undefined if the value passed to this function
+** is less than zero.
+*/
+static int sqlite3Fts5UnicodeIsalnum(int c){
+  /* Each unsigned integer in the following array corresponds to a contiguous
+  ** range of unicode codepoints that are not either letters or numbers (i.e.
+  ** codepoints for which this function should return 0).
+  **
+  ** The most significant 22 bits in each 32-bit value contain the first 
+  ** codepoint in the range. The least significant 10 bits are used to store
+  ** the size of the range (always at least 1). In other words, the value 
+  ** ((C<<22) + N) represents a range of N codepoints starting with codepoint 
+  ** C. It is not possible to represent a range larger than 1023 codepoints 
+  ** using this format.
+  */
+  static const unsigned int aEntry[] = {
+    0x00000030, 0x0000E807, 0x00016C06, 0x0001EC2F, 0x0002AC07,
+    0x0002D001, 0x0002D803, 0x0002EC01, 0x0002FC01, 0x00035C01,
+    0x0003DC01, 0x000B0804, 0x000B480E, 0x000B9407, 0x000BB401,
+    0x000BBC81, 0x000DD401, 0x000DF801, 0x000E1002, 0x000E1C01,
+    0x000FD801, 0x00120808, 0x00156806, 0x00162402, 0x00163C01,
+    0x00164437, 0x0017CC02, 0x00180005, 0x00181816, 0x00187802,
+    0x00192C15, 0x0019A804, 0x0019C001, 0x001B5001, 0x001B580F,
+    0x001B9C07, 0x001BF402, 0x001C000E, 0x001C3C01, 0x001C4401,
+    0x001CC01B, 0x001E980B, 0x001FAC09, 0x001FD804, 0x00205804,
+    0x00206C09, 0x00209403, 0x0020A405, 0x0020C00F, 0x00216403,
+    0x00217801, 0x0023901B, 0x00240004, 0x0024E803, 0x0024F812,
+    0x00254407, 0x00258804, 0x0025C001, 0x00260403, 0x0026F001,
+    0x0026F807, 0x00271C02, 0x00272C03, 0x00275C01, 0x00278802,
+    0x0027C802, 0x0027E802, 0x00280403, 0x0028F001, 0x0028F805,
+    0x00291C02, 0x00292C03, 0x00294401, 0x0029C002, 0x0029D401,
+    0x002A0403, 0x002AF001, 0x002AF808, 0x002B1C03, 0x002B2C03,
+    0x002B8802, 0x002BC002, 0x002C0403, 0x002CF001, 0x002CF807,
+    0x002D1C02, 0x002D2C03, 0x002D5802, 0x002D8802, 0x002DC001,
+    0x002E0801, 0x002EF805, 0x002F1803, 0x002F2804, 0x002F5C01,
+    0x002FCC08, 0x00300403, 0x0030F807, 0x00311803, 0x00312804,
+    0x00315402, 0x00318802, 0x0031FC01, 0x00320802, 0x0032F001,
+    0x0032F807, 0x00331803, 0x00332804, 0x00335402, 0x00338802,
+    0x00340802, 0x0034F807, 0x00351803, 0x00352804, 0x00355C01,
+    0x00358802, 0x0035E401, 0x00360802, 0x00372801, 0x00373C06,
+    0x00375801, 0x00376008, 0x0037C803, 0x0038C401, 0x0038D007,
+    0x0038FC01, 0x00391C09, 0x00396802, 0x003AC401, 0x003AD006,
+    0x003AEC02, 0x003B2006, 0x003C041F, 0x003CD00C, 0x003DC417,
+    0x003E340B, 0x003E6424, 0x003EF80F, 0x003F380D, 0x0040AC14,
+    0x00412806, 0x00415804, 0x00417803, 0x00418803, 0x00419C07,
+    0x0041C404, 0x0042080C, 0x00423C01, 0x00426806, 0x0043EC01,
+    0x004D740C, 0x004E400A, 0x00500001, 0x0059B402, 0x005A0001,
+    0x005A6C02, 0x005BAC03, 0x005C4803, 0x005CC805, 0x005D4802,
+    0x005DC802, 0x005ED023, 0x005F6004, 0x005F7401, 0x0060000F,
+    0x0062A401, 0x0064800C, 0x0064C00C, 0x00650001, 0x00651002,
+    0x0066C011, 0x00672002, 0x00677822, 0x00685C05, 0x00687802,
+    0x0069540A, 0x0069801D, 0x0069FC01, 0x006A8007, 0x006AA006,
+    0x006C0005, 0x006CD011, 0x006D6823, 0x006E0003, 0x006E840D,
+    0x006F980E, 0x006FF004, 0x00709014, 0x0070EC05, 0x0071F802,
+    0x00730008, 0x00734019, 0x0073B401, 0x0073C803, 0x00770027,
+    0x0077F004, 0x007EF401, 0x007EFC03, 0x007F3403, 0x007F7403,
+    0x007FB403, 0x007FF402, 0x00800065, 0x0081A806, 0x0081E805,
+    0x00822805, 0x0082801A, 0x00834021, 0x00840002, 0x00840C04,
+    0x00842002, 0x00845001, 0x00845803, 0x00847806, 0x00849401,
+    0x00849C01, 0x0084A401, 0x0084B801, 0x0084E802, 0x00850005,
+    0x00852804, 0x00853C01, 0x00864264, 0x00900027, 0x0091000B,
+    0x0092704E, 0x00940200, 0x009C0475, 0x009E53B9, 0x00AD400A,
+    0x00B39406, 0x00B3BC03, 0x00B3E404, 0x00B3F802, 0x00B5C001,
+    0x00B5FC01, 0x00B7804F, 0x00B8C00C, 0x00BA001A, 0x00BA6C59,
+    0x00BC00D6, 0x00BFC00C, 0x00C00005, 0x00C02019, 0x00C0A807,
+    0x00C0D802, 0x00C0F403, 0x00C26404, 0x00C28001, 0x00C3EC01,
+    0x00C64002, 0x00C6580A, 0x00C70024, 0x00C8001F, 0x00C8A81E,
+    0x00C94001, 0x00C98020, 0x00CA2827, 0x00CB003F, 0x00CC0100,
+    0x01370040, 0x02924037, 0x0293F802, 0x02983403, 0x0299BC10,
+    0x029A7C01, 0x029BC008, 0x029C0017, 0x029C8002, 0x029E2402,
+    0x02A00801, 0x02A01801, 0x02A02C01, 0x02A08C09, 0x02A0D804,
+    0x02A1D004, 0x02A20002, 0x02A2D011, 0x02A33802, 0x02A38012,
+    0x02A3E003, 0x02A4980A, 0x02A51C0D, 0x02A57C01, 0x02A60004,
+    0x02A6CC1B, 0x02A77802, 0x02A8A40E, 0x02A90C01, 0x02A93002,
+    0x02A97004, 0x02A9DC03, 0x02A9EC01, 0x02AAC001, 0x02AAC803,
+    0x02AADC02, 0x02AAF802, 0x02AB0401, 0x02AB7802, 0x02ABAC07,
+    0x02ABD402, 0x02AF8C0B, 0x03600001, 0x036DFC02, 0x036FFC02,
+    0x037FFC01, 0x03EC7801, 0x03ECA401, 0x03EEC810, 0x03F4F802,
+    0x03F7F002, 0x03F8001A, 0x03F88007, 0x03F8C023, 0x03F95013,
+    0x03F9A004, 0x03FBFC01, 0x03FC040F, 0x03FC6807, 0x03FCEC06,
+    0x03FD6C0B, 0x03FF8007, 0x03FFA007, 0x03FFE405, 0x04040003,
+    0x0404DC09, 0x0405E411, 0x0406400C, 0x0407402E, 0x040E7C01,
+    0x040F4001, 0x04215C01, 0x04247C01, 0x0424FC01, 0x04280403,
+    0x04281402, 0x04283004, 0x0428E003, 0x0428FC01, 0x04294009,
+    0x0429FC01, 0x042CE407, 0x04400003, 0x0440E016, 0x04420003,
+    0x0442C012, 0x04440003, 0x04449C0E, 0x04450004, 0x04460003,
+    0x0446CC0E, 0x04471404, 0x045AAC0D, 0x0491C004, 0x05BD442E,
+    0x05BE3C04, 0x074000F6, 0x07440027, 0x0744A4B5, 0x07480046,
+    0x074C0057, 0x075B0401, 0x075B6C01, 0x075BEC01, 0x075C5401,
+    0x075CD401, 0x075D3C01, 0x075DBC01, 0x075E2401, 0x075EA401,
+    0x075F0C01, 0x07BBC002, 0x07C0002C, 0x07C0C064, 0x07C2800F,
+    0x07C2C40E, 0x07C3040F, 0x07C3440F, 0x07C4401F, 0x07C4C03C,
+    0x07C5C02B, 0x07C7981D, 0x07C8402B, 0x07C90009, 0x07C94002,
+    0x07CC0021, 0x07CCC006, 0x07CCDC46, 0x07CE0014, 0x07CE8025,
+    0x07CF1805, 0x07CF8011, 0x07D0003F, 0x07D10001, 0x07D108B6,
+    0x07D3E404, 0x07D4003E, 0x07D50004, 0x07D54018, 0x07D7EC46,
+    0x07D9140B, 0x07DA0046, 0x07DC0074, 0x38000401, 0x38008060,
+    0x380400F0,
+  };
+  static const unsigned int aAscii[4] = {
+    0xFFFFFFFF, 0xFC00FFFF, 0xF8000001, 0xF8000001,
+  };
+
+  if( (unsigned int)c<128 ){
+    return ( (aAscii[c >> 5] & (1 << (c & 0x001F)))==0 );
+  }else if( (unsigned int)c<(1<<22) ){
+    unsigned int key = (((unsigned int)c)<<10) | 0x000003FF;
+    int iRes = 0;
+    int iHi = sizeof(aEntry)/sizeof(aEntry[0]) - 1;
+    int iLo = 0;
+    while( iHi>=iLo ){
+      int iTest = (iHi + iLo) / 2;
+      if( key >= aEntry[iTest] ){
+        iRes = iTest;
+        iLo = iTest+1;
+      }else{
+        iHi = iTest-1;
+      }
+    }
+    assert( aEntry[0]<key );
+    assert( key>=aEntry[iRes] );
+    return (((unsigned int)c) >= ((aEntry[iRes]>>10) + (aEntry[iRes]&0x3FF)));
+  }
+  return 1;
+}
+
+
+/*
+** If the argument is a codepoint corresponding to a lowercase letter
+** in the ASCII range with a diacritic added, return the codepoint
+** of the ASCII letter only. For example, if passed 235 - "LATIN
+** SMALL LETTER E WITH DIAERESIS" - return 65 ("LATIN SMALL LETTER
+** E"). The resuls of passing a codepoint that corresponds to an
+** uppercase letter are undefined.
+*/
+static int fts5_remove_diacritic(int c){
+  unsigned short aDia[] = {
+        0,  1797,  1848,  1859,  1891,  1928,  1940,  1995, 
+     2024,  2040,  2060,  2110,  2168,  2206,  2264,  2286, 
+     2344,  2383,  2472,  2488,  2516,  2596,  2668,  2732, 
+     2782,  2842,  2894,  2954,  2984,  3000,  3028,  3336, 
+     3456,  3696,  3712,  3728,  3744,  3896,  3912,  3928, 
+     3968,  4008,  4040,  4106,  4138,  4170,  4202,  4234, 
+     4266,  4296,  4312,  4344,  4408,  4424,  4472,  4504, 
+     6148,  6198,  6264,  6280,  6360,  6429,  6505,  6529, 
+    61448, 61468, 61534, 61592, 61642, 61688, 61704, 61726, 
+    61784, 61800, 61836, 61880, 61914, 61948, 61998, 62122, 
+    62154, 62200, 62218, 62302, 62364, 62442, 62478, 62536, 
+    62554, 62584, 62604, 62640, 62648, 62656, 62664, 62730, 
+    62924, 63050, 63082, 63274, 63390, 
+  };
+  char aChar[] = {
+    '\0', 'a',  'c',  'e',  'i',  'n',  'o',  'u',  'y',  'y',  'a',  'c',  
+    'd',  'e',  'e',  'g',  'h',  'i',  'j',  'k',  'l',  'n',  'o',  'r',  
+    's',  't',  'u',  'u',  'w',  'y',  'z',  'o',  'u',  'a',  'i',  'o',  
+    'u',  'g',  'k',  'o',  'j',  'g',  'n',  'a',  'e',  'i',  'o',  'r',  
+    'u',  's',  't',  'h',  'a',  'e',  'o',  'y',  '\0', '\0', '\0', '\0', 
+    '\0', '\0', '\0', '\0', 'a',  'b',  'd',  'd',  'e',  'f',  'g',  'h',  
+    'h',  'i',  'k',  'l',  'l',  'm',  'n',  'p',  'r',  'r',  's',  't',  
+    'u',  'v',  'w',  'w',  'x',  'y',  'z',  'h',  't',  'w',  'y',  'a',  
+    'e',  'i',  'o',  'u',  'y',  
+  };
+
+  unsigned int key = (((unsigned int)c)<<3) | 0x00000007;
+  int iRes = 0;
+  int iHi = sizeof(aDia)/sizeof(aDia[0]) - 1;
+  int iLo = 0;
+  while( iHi>=iLo ){
+    int iTest = (iHi + iLo) / 2;
+    if( key >= aDia[iTest] ){
+      iRes = iTest;
+      iLo = iTest+1;
+    }else{
+      iHi = iTest-1;
+    }
+  }
+  assert( key>=aDia[iRes] );
+  return ((c > (aDia[iRes]>>3) + (aDia[iRes]&0x07)) ? c : (int)aChar[iRes]);
+}
+
+
+/*
+** Return true if the argument interpreted as a unicode codepoint
+** is a diacritical modifier character.
+*/
+static int sqlite3Fts5UnicodeIsdiacritic(int c){
+  unsigned int mask0 = 0x08029FDF;
+  unsigned int mask1 = 0x000361F8;
+  if( c<768 || c>817 ) return 0;
+  return (c < 768+32) ?
+      (mask0 & (1 << (c-768))) :
+      (mask1 & (1 << (c-768-32)));
+}
+
+
+/*
+** Interpret the argument as a unicode codepoint. If the codepoint
+** is an upper case character that has a lower case equivalent,
+** return the codepoint corresponding to the lower case version.
+** Otherwise, return a copy of the argument.
+**
+** The results are undefined if the value passed to this function
+** is less than zero.
+*/
+static int sqlite3Fts5UnicodeFold(int c, int bRemoveDiacritic){
+  /* Each entry in the following array defines a rule for folding a range
+  ** of codepoints to lower case. The rule applies to a range of nRange
+  ** codepoints starting at codepoint iCode.
+  **
+  ** If the least significant bit in flags is clear, then the rule applies
+  ** to all nRange codepoints (i.e. all nRange codepoints are upper case and
+  ** need to be folded). Or, if it is set, then the rule only applies to
+  ** every second codepoint in the range, starting with codepoint C.
+  **
+  ** The 7 most significant bits in flags are an index into the aiOff[]
+  ** array. If a specific codepoint C does require folding, then its lower
+  ** case equivalent is ((C + aiOff[flags>>1]) & 0xFFFF).
+  **
+  ** The contents of this array are generated by parsing the CaseFolding.txt
+  ** file distributed as part of the "Unicode Character Database". See
+  ** http://www.unicode.org for details.
+  */
+  static const struct TableEntry {
+    unsigned short iCode;
+    unsigned char flags;
+    unsigned char nRange;
+  } aEntry[] = {
+    {65, 14, 26},          {181, 64, 1},          {192, 14, 23},
+    {216, 14, 7},          {256, 1, 48},          {306, 1, 6},
+    {313, 1, 16},          {330, 1, 46},          {376, 116, 1},
+    {377, 1, 6},           {383, 104, 1},         {385, 50, 1},
+    {386, 1, 4},           {390, 44, 1},          {391, 0, 1},
+    {393, 42, 2},          {395, 0, 1},           {398, 32, 1},
+    {399, 38, 1},          {400, 40, 1},          {401, 0, 1},
+    {403, 42, 1},          {404, 46, 1},          {406, 52, 1},
+    {407, 48, 1},          {408, 0, 1},           {412, 52, 1},
+    {413, 54, 1},          {415, 56, 1},          {416, 1, 6},
+    {422, 60, 1},          {423, 0, 1},           {425, 60, 1},
+    {428, 0, 1},           {430, 60, 1},          {431, 0, 1},
+    {433, 58, 2},          {435, 1, 4},           {439, 62, 1},
+    {440, 0, 1},           {444, 0, 1},           {452, 2, 1},
+    {453, 0, 1},           {455, 2, 1},           {456, 0, 1},
+    {458, 2, 1},           {459, 1, 18},          {478, 1, 18},
+    {497, 2, 1},           {498, 1, 4},           {502, 122, 1},
+    {503, 134, 1},         {504, 1, 40},          {544, 110, 1},
+    {546, 1, 18},          {570, 70, 1},          {571, 0, 1},
+    {573, 108, 1},         {574, 68, 1},          {577, 0, 1},
+    {579, 106, 1},         {580, 28, 1},          {581, 30, 1},
+    {582, 1, 10},          {837, 36, 1},          {880, 1, 4},
+    {886, 0, 1},           {902, 18, 1},          {904, 16, 3},
+    {908, 26, 1},          {910, 24, 2},          {913, 14, 17},
+    {931, 14, 9},          {962, 0, 1},           {975, 4, 1},
+    {976, 140, 1},         {977, 142, 1},         {981, 146, 1},
+    {982, 144, 1},         {984, 1, 24},          {1008, 136, 1},
+    {1009, 138, 1},        {1012, 130, 1},        {1013, 128, 1},
+    {1015, 0, 1},          {1017, 152, 1},        {1018, 0, 1},
+    {1021, 110, 3},        {1024, 34, 16},        {1040, 14, 32},
+    {1120, 1, 34},         {1162, 1, 54},         {1216, 6, 1},
+    {1217, 1, 14},         {1232, 1, 88},         {1329, 22, 38},
+    {4256, 66, 38},        {4295, 66, 1},         {4301, 66, 1},
+    {7680, 1, 150},        {7835, 132, 1},        {7838, 96, 1},
+    {7840, 1, 96},         {7944, 150, 8},        {7960, 150, 6},
+    {7976, 150, 8},        {7992, 150, 8},        {8008, 150, 6},
+    {8025, 151, 8},        {8040, 150, 8},        {8072, 150, 8},
+    {8088, 150, 8},        {8104, 150, 8},        {8120, 150, 2},
+    {8122, 126, 2},        {8124, 148, 1},        {8126, 100, 1},
+    {8136, 124, 4},        {8140, 148, 1},        {8152, 150, 2},
+    {8154, 120, 2},        {8168, 150, 2},        {8170, 118, 2},
+    {8172, 152, 1},        {8184, 112, 2},        {8186, 114, 2},
+    {8188, 148, 1},        {8486, 98, 1},         {8490, 92, 1},
+    {8491, 94, 1},         {8498, 12, 1},         {8544, 8, 16},
+    {8579, 0, 1},          {9398, 10, 26},        {11264, 22, 47},
+    {11360, 0, 1},         {11362, 88, 1},        {11363, 102, 1},
+    {11364, 90, 1},        {11367, 1, 6},         {11373, 84, 1},
+    {11374, 86, 1},        {11375, 80, 1},        {11376, 82, 1},
+    {11378, 0, 1},         {11381, 0, 1},         {11390, 78, 2},
+    {11392, 1, 100},       {11499, 1, 4},         {11506, 0, 1},
+    {42560, 1, 46},        {42624, 1, 24},        {42786, 1, 14},
+    {42802, 1, 62},        {42873, 1, 4},         {42877, 76, 1},
+    {42878, 1, 10},        {42891, 0, 1},         {42893, 74, 1},
+    {42896, 1, 4},         {42912, 1, 10},        {42922, 72, 1},
+    {65313, 14, 26},       
+  };
+  static const unsigned short aiOff[] = {
+   1,     2,     8,     15,    16,    26,    28,    32,    
+   37,    38,    40,    48,    63,    64,    69,    71,    
+   79,    80,    116,   202,   203,   205,   206,   207,   
+   209,   210,   211,   213,   214,   217,   218,   219,   
+   775,   7264,  10792, 10795, 23228, 23256, 30204, 54721, 
+   54753, 54754, 54756, 54787, 54793, 54809, 57153, 57274, 
+   57921, 58019, 58363, 61722, 65268, 65341, 65373, 65406, 
+   65408, 65410, 65415, 65424, 65436, 65439, 65450, 65462, 
+   65472, 65476, 65478, 65480, 65482, 65488, 65506, 65511, 
+   65514, 65521, 65527, 65528, 65529, 
+  };
+
+  int ret = c;
+
+  assert( sizeof(unsigned short)==2 && sizeof(unsigned char)==1 );
+
+  if( c<128 ){
+    if( c>='A' && c<='Z' ) ret = c + ('a' - 'A');
+  }else if( c<65536 ){
+    const struct TableEntry *p;
+    int iHi = sizeof(aEntry)/sizeof(aEntry[0]) - 1;
+    int iLo = 0;
+    int iRes = -1;
+
+    assert( c>aEntry[0].iCode );
+    while( iHi>=iLo ){
+      int iTest = (iHi + iLo) / 2;
+      int cmp = (c - aEntry[iTest].iCode);
+      if( cmp>=0 ){
+        iRes = iTest;
+        iLo = iTest+1;
+      }else{
+        iHi = iTest-1;
+      }
+    }
+
+    assert( iRes>=0 && c>=aEntry[iRes].iCode );
+    p = &aEntry[iRes];
+    if( c<(p->iCode + p->nRange) && 0==(0x01 & p->flags & (p->iCode ^ c)) ){
+      ret = (c + (aiOff[p->flags>>1])) & 0x0000FFFF;
+      assert( ret>0 );
+    }
+
+    if( bRemoveDiacritic ) ret = fts5_remove_diacritic(ret);
+  }
+  
+  else if( c>=66560 && c<66600 ){
+    ret = c + 40;
+  }
+
+  return ret;
+}
+
+/*
+** 2015 May 30
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** Routines for varint serialization and deserialization.
+*/
+
+
+/* #include "fts5Int.h" */
+
+/*
+** This is a copy of the sqlite3GetVarint32() routine from the SQLite core.
+** Except, this version does handle the single byte case that the core
+** version depends on being handled before its function is called.
+*/
+static int sqlite3Fts5GetVarint32(const unsigned char *p, u32 *v){
+  u32 a,b;
+
+  /* The 1-byte case. Overwhelmingly the most common. */
+  a = *p;
+  /* a: p0 (unmasked) */
+  if (!(a&0x80))
+  {
+    /* Values between 0 and 127 */
+    *v = a;
+    return 1;
+  }
+
+  /* The 2-byte case */
+  p++;
+  b = *p;
+  /* b: p1 (unmasked) */
+  if (!(b&0x80))
+  {
+    /* Values between 128 and 16383 */
+    a &= 0x7f;
+    a = a<<7;
+    *v = a | b;
+    return 2;
+  }
+
+  /* The 3-byte case */
+  p++;
+  a = a<<14;
+  a |= *p;
+  /* a: p0<<14 | p2 (unmasked) */
+  if (!(a&0x80))
+  {
+    /* Values between 16384 and 2097151 */
+    a &= (0x7f<<14)|(0x7f);
+    b &= 0x7f;
+    b = b<<7;
+    *v = a | b;
+    return 3;
+  }
+
+  /* A 32-bit varint is used to store size information in btrees.
+  ** Objects are rarely larger than 2MiB limit of a 3-byte varint.
+  ** A 3-byte varint is sufficient, for example, to record the size
+  ** of a 1048569-byte BLOB or string.
+  **
+  ** We only unroll the first 1-, 2-, and 3- byte cases.  The very
+  ** rare larger cases can be handled by the slower 64-bit varint
+  ** routine.
+  */
+  {
+    u64 v64;
+    u8 n;
+    p -= 2;
+    n = sqlite3Fts5GetVarint(p, &v64);
+    *v = (u32)v64;
+    assert( n>3 && n<=9 );
+    return n;
+  }
+}
+
+
+/*
+** Bitmasks used by sqlite3GetVarint().  These precomputed constants
+** are defined here rather than simply putting the constant expressions
+** inline in order to work around bugs in the RVT compiler.
+**
+** SLOT_2_0     A mask for  (0x7f<<14) | 0x7f
+**
+** SLOT_4_2_0   A mask for  (0x7f<<28) | SLOT_2_0
+*/
+#define SLOT_2_0     0x001fc07f
+#define SLOT_4_2_0   0xf01fc07f
+
+/*
+** Read a 64-bit variable-length integer from memory starting at p[0].
+** Return the number of bytes read.  The value is stored in *v.
+*/
+static u8 sqlite3Fts5GetVarint(const unsigned char *p, u64 *v){
+  u32 a,b,s;
+
+  a = *p;
+  /* a: p0 (unmasked) */
+  if (!(a&0x80))
+  {
+    *v = a;
+    return 1;
+  }
+
+  p++;
+  b = *p;
+  /* b: p1 (unmasked) */
+  if (!(b&0x80))
+  {
+    a &= 0x7f;
+    a = a<<7;
+    a |= b;
+    *v = a;
+    return 2;
+  }
+
+  /* Verify that constants are precomputed correctly */
+  assert( SLOT_2_0 == ((0x7f<<14) | (0x7f)) );
+  assert( SLOT_4_2_0 == ((0xfU<<28) | (0x7f<<14) | (0x7f)) );
+
+  p++;
+  a = a<<14;
+  a |= *p;
+  /* a: p0<<14 | p2 (unmasked) */
+  if (!(a&0x80))
+  {
+    a &= SLOT_2_0;
+    b &= 0x7f;
+    b = b<<7;
+    a |= b;
+    *v = a;
+    return 3;
+  }
+
+  /* CSE1 from below */
+  a &= SLOT_2_0;
+  p++;
+  b = b<<14;
+  b |= *p;
+  /* b: p1<<14 | p3 (unmasked) */
+  if (!(b&0x80))
+  {
+    b &= SLOT_2_0;
+    /* moved CSE1 up */
+    /* a &= (0x7f<<14)|(0x7f); */
+    a = a<<7;
+    a |= b;
+    *v = a;
+    return 4;
+  }
+
+  /* a: p0<<14 | p2 (masked) */
+  /* b: p1<<14 | p3 (unmasked) */
+  /* 1:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
+  /* moved CSE1 up */
+  /* a &= (0x7f<<14)|(0x7f); */
+  b &= SLOT_2_0;
+  s = a;
+  /* s: p0<<14 | p2 (masked) */
+
+  p++;
+  a = a<<14;
+  a |= *p;
+  /* a: p0<<28 | p2<<14 | p4 (unmasked) */
+  if (!(a&0x80))
+  {
+    /* we can skip these cause they were (effectively) done above in calc'ing s */
+    /* a &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
+    /* b &= (0x7f<<14)|(0x7f); */
+    b = b<<7;
+    a |= b;
+    s = s>>18;
+    *v = ((u64)s)<<32 | a;
+    return 5;
+  }
+
+  /* 2:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
+  s = s<<7;
+  s |= b;
+  /* s: p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
+
+  p++;
+  b = b<<14;
+  b |= *p;
+  /* b: p1<<28 | p3<<14 | p5 (unmasked) */
+  if (!(b&0x80))
+  {
+    /* we can skip this cause it was (effectively) done above in calc'ing s */
+    /* b &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
+    a &= SLOT_2_0;
+    a = a<<7;
+    a |= b;
+    s = s>>18;
+    *v = ((u64)s)<<32 | a;
+    return 6;
+  }
+
+  p++;
+  a = a<<14;
+  a |= *p;
+  /* a: p2<<28 | p4<<14 | p6 (unmasked) */
+  if (!(a&0x80))
+  {
+    a &= SLOT_4_2_0;
+    b &= SLOT_2_0;
+    b = b<<7;
+    a |= b;
+    s = s>>11;
+    *v = ((u64)s)<<32 | a;
+    return 7;
+  }
+
+  /* CSE2 from below */
+  a &= SLOT_2_0;
+  p++;
+  b = b<<14;
+  b |= *p;
+  /* b: p3<<28 | p5<<14 | p7 (unmasked) */
+  if (!(b&0x80))
+  {
+    b &= SLOT_4_2_0;
+    /* moved CSE2 up */
+    /* a &= (0x7f<<14)|(0x7f); */
+    a = a<<7;
+    a |= b;
+    s = s>>4;
+    *v = ((u64)s)<<32 | a;
+    return 8;
+  }
+
+  p++;
+  a = a<<15;
+  a |= *p;
+  /* a: p4<<29 | p6<<15 | p8 (unmasked) */
+
+  /* moved CSE2 up */
+  /* a &= (0x7f<<29)|(0x7f<<15)|(0xff); */
+  b &= SLOT_2_0;
+  b = b<<8;
+  a |= b;
+
+  s = s<<4;
+  b = p[-4];
+  b &= 0x7f;
+  b = b>>3;
+  s |= b;
+
+  *v = ((u64)s)<<32 | a;
+
+  return 9;
+}
+
+/*
+** The variable-length integer encoding is as follows:
+**
+** KEY:
+**         A = 0xxxxxxx    7 bits of data and one flag bit
+**         B = 1xxxxxxx    7 bits of data and one flag bit
+**         C = xxxxxxxx    8 bits of data
+**
+**  7 bits - A
+** 14 bits - BA
+** 21 bits - BBA
+** 28 bits - BBBA
+** 35 bits - BBBBA
+** 42 bits - BBBBBA
+** 49 bits - BBBBBBA
+** 56 bits - BBBBBBBA
+** 64 bits - BBBBBBBBC
+*/
+
+#ifdef SQLITE_NOINLINE
+# define FTS5_NOINLINE SQLITE_NOINLINE
+#else
+# define FTS5_NOINLINE
+#endif
+
+/*
+** Write a 64-bit variable-length integer to memory starting at p[0].
+** The length of data write will be between 1 and 9 bytes.  The number
+** of bytes written is returned.
+**
+** A variable-length integer consists of the lower 7 bits of each byte
+** for all bytes that have the 8th bit set and one byte with the 8th
+** bit clear.  Except, if we get to the 9th byte, it stores the full
+** 8 bits and is the last byte.
+*/
+static int FTS5_NOINLINE fts5PutVarint64(unsigned char *p, u64 v){
+  int i, j, n;
+  u8 buf[10];
+  if( v & (((u64)0xff000000)<<32) ){
+    p[8] = (u8)v;
+    v >>= 8;
+    for(i=7; i>=0; i--){
+      p[i] = (u8)((v & 0x7f) | 0x80);
+      v >>= 7;
+    }
+    return 9;
+  }    
+  n = 0;
+  do{
+    buf[n++] = (u8)((v & 0x7f) | 0x80);
+    v >>= 7;
+  }while( v!=0 );
+  buf[0] &= 0x7f;
+  assert( n<=9 );
+  for(i=0, j=n-1; j>=0; j--, i++){
+    p[i] = buf[j];
+  }
+  return n;
+}
+
+static int sqlite3Fts5PutVarint(unsigned char *p, u64 v){
+  if( v<=0x7f ){
+    p[0] = v&0x7f;
+    return 1;
+  }
+  if( v<=0x3fff ){
+    p[0] = ((v>>7)&0x7f)|0x80;
+    p[1] = v&0x7f;
+    return 2;
+  }
+  return fts5PutVarint64(p,v);
+}
+
+
+static int sqlite3Fts5GetVarintLen(u32 iVal){
+#if 0
+  if( iVal<(1 << 7 ) ) return 1;
+#endif
+  assert( iVal>=(1 << 7) );
+  if( iVal<(1 << 14) ) return 2;
+  if( iVal<(1 << 21) ) return 3;
+  if( iVal<(1 << 28) ) return 4;
+  return 5;
+}
+
+
+/*
+** 2015 May 08
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This is an SQLite virtual table module implementing direct access to an
+** existing FTS5 index. The module may create several different types of 
+** tables:
+**
+** col:
+**     CREATE TABLE vocab(term, col, doc, cnt, PRIMARY KEY(term, col));
+**
+**   One row for each term/column combination. The value of $doc is set to
+**   the number of fts5 rows that contain at least one instance of term
+**   $term within column $col. Field $cnt is set to the total number of 
+**   instances of term $term in column $col (in any row of the fts5 table). 
+**
+** row:
+**     CREATE TABLE vocab(term, doc, cnt, PRIMARY KEY(term));
+**
+**   One row for each term in the database. The value of $doc is set to
+**   the number of fts5 rows that contain at least one instance of term
+**   $term. Field $cnt is set to the total number of instances of term 
+**   $term in the database.
+*/
+
+
+/* #include "fts5Int.h" */
+
+
+typedef struct Fts5VocabTable Fts5VocabTable;
+typedef struct Fts5VocabCursor Fts5VocabCursor;
+
+struct Fts5VocabTable {
+  sqlite3_vtab base;
+  char *zFts5Tbl;                 /* Name of fts5 table */
+  char *zFts5Db;                  /* Db containing fts5 table */
+  sqlite3 *db;                    /* Database handle */
+  Fts5Global *pGlobal;            /* FTS5 global object for this database */
+  int eType;                      /* FTS5_VOCAB_COL or ROW */
+};
+
+struct Fts5VocabCursor {
+  sqlite3_vtab_cursor base;
+  sqlite3_stmt *pStmt;            /* Statement holding lock on pIndex */
+  Fts5Index *pIndex;              /* Associated FTS5 index */
+
+  int bEof;                       /* True if this cursor is at EOF */
+  Fts5IndexIter *pIter;           /* Term/rowid iterator object */
+
+  int nLeTerm;                    /* Size of zLeTerm in bytes */
+  char *zLeTerm;                  /* (term <= $zLeTerm) paramater, or NULL */
+
+  /* These are used by 'col' tables only */
+  Fts5Config *pConfig;            /* Fts5 table configuration */
+  int iCol;
+  i64 *aCnt;
+  i64 *aDoc;
+
+  /* Output values used by 'row' and 'col' tables */
+  i64 rowid;                      /* This table's current rowid value */
+  Fts5Buffer term;                /* Current value of 'term' column */
+};
+
+#define FTS5_VOCAB_COL    0
+#define FTS5_VOCAB_ROW    1
+
+#define FTS5_VOCAB_COL_SCHEMA  "term, col, doc, cnt"
+#define FTS5_VOCAB_ROW_SCHEMA  "term, doc, cnt"
+
+/*
+** Bits for the mask used as the idxNum value by xBestIndex/xFilter.
+*/
+#define FTS5_VOCAB_TERM_EQ 0x01
+#define FTS5_VOCAB_TERM_GE 0x02
+#define FTS5_VOCAB_TERM_LE 0x04
+
+
+/*
+** Translate a string containing an fts5vocab table type to an 
+** FTS5_VOCAB_XXX constant. If successful, set *peType to the output
+** value and return SQLITE_OK. Otherwise, set *pzErr to an error message
+** and return SQLITE_ERROR.
+*/
+static int fts5VocabTableType(const char *zType, char **pzErr, int *peType){
+  int rc = SQLITE_OK;
+  char *zCopy = sqlite3Fts5Strndup(&rc, zType, -1);
+  if( rc==SQLITE_OK ){
+    sqlite3Fts5Dequote(zCopy);
+    if( sqlite3_stricmp(zCopy, "col")==0 ){
+      *peType = FTS5_VOCAB_COL;
+    }else
+
+    if( sqlite3_stricmp(zCopy, "row")==0 ){
+      *peType = FTS5_VOCAB_ROW;
+    }else
+    {
+      *pzErr = sqlite3_mprintf("fts5vocab: unknown table type: %Q", zCopy);
+      rc = SQLITE_ERROR;
+    }
+    sqlite3_free(zCopy);
+  }
+
+  return rc;
+}
+
+
+/*
+** The xDisconnect() virtual table method.
+*/
+static int fts5VocabDisconnectMethod(sqlite3_vtab *pVtab){
+  Fts5VocabTable *pTab = (Fts5VocabTable*)pVtab;
+  sqlite3_free(pTab);
+  return SQLITE_OK;
+}
+
+/*
+** The xDestroy() virtual table method.
+*/
+static int fts5VocabDestroyMethod(sqlite3_vtab *pVtab){
+  Fts5VocabTable *pTab = (Fts5VocabTable*)pVtab;
+  sqlite3_free(pTab);
+  return SQLITE_OK;
+}
+
+/*
+** This function is the implementation of both the xConnect and xCreate
+** methods of the FTS3 virtual table.
+**
+** The argv[] array contains the following:
+**
+**   argv[0]   -> module name  ("fts5vocab")
+**   argv[1]   -> database name
+**   argv[2]   -> table name
+**
+** then:
+**
+**   argv[3]   -> name of fts5 table
+**   argv[4]   -> type of fts5vocab table
+**
+** or, for tables in the TEMP schema only.
+**
+**   argv[3]   -> name of fts5 tables database
+**   argv[4]   -> name of fts5 table
+**   argv[5]   -> type of fts5vocab table
+*/
+static int fts5VocabInitVtab(
+  sqlite3 *db,                    /* The SQLite database connection */
+  void *pAux,                     /* Pointer to Fts5Global object */
+  int argc,                       /* Number of elements in argv array */
+  const char * const *argv,       /* xCreate/xConnect argument array */
+  sqlite3_vtab **ppVTab,          /* Write the resulting vtab structure here */
+  char **pzErr                    /* Write any error message here */
+){
+  const char *azSchema[] = { 
+    "CREATE TABlE vocab(" FTS5_VOCAB_COL_SCHEMA  ")", 
+    "CREATE TABlE vocab(" FTS5_VOCAB_ROW_SCHEMA  ")"
+  };
+
+  Fts5VocabTable *pRet = 0;
+  int rc = SQLITE_OK;             /* Return code */
+  int bDb;
+
+  bDb = (argc==6 && strlen(argv[1])==4 && memcmp("temp", argv[1], 4)==0);
+
+  if( argc!=5 && bDb==0 ){
+    *pzErr = sqlite3_mprintf("wrong number of vtable arguments");
+    rc = SQLITE_ERROR;
+  }else{
+    int nByte;                      /* Bytes of space to allocate */
+    const char *zDb = bDb ? argv[3] : argv[1];
+    const char *zTab = bDb ? argv[4] : argv[3];
+    const char *zType = bDb ? argv[5] : argv[4];
+    int nDb = (int)strlen(zDb)+1; 
+    int nTab = (int)strlen(zTab)+1;
+    int eType = 0;
+    
+    rc = fts5VocabTableType(zType, pzErr, &eType);
+    if( rc==SQLITE_OK ){
+      assert( eType>=0 && eType<ArraySize(azSchema) );
+      rc = sqlite3_declare_vtab(db, azSchema[eType]);
+    }
+
+    nByte = sizeof(Fts5VocabTable) + nDb + nTab;
+    pRet = sqlite3Fts5MallocZero(&rc, nByte);
+    if( pRet ){
+      pRet->pGlobal = (Fts5Global*)pAux;
+      pRet->eType = eType;
+      pRet->db = db;
+      pRet->zFts5Tbl = (char*)&pRet[1];
+      pRet->zFts5Db = &pRet->zFts5Tbl[nTab];
+      memcpy(pRet->zFts5Tbl, zTab, nTab);
+      memcpy(pRet->zFts5Db, zDb, nDb);
+      sqlite3Fts5Dequote(pRet->zFts5Tbl);
+      sqlite3Fts5Dequote(pRet->zFts5Db);
+    }
+  }
+
+  *ppVTab = (sqlite3_vtab*)pRet;
+  return rc;
+}
+
+
+/*
+** The xConnect() and xCreate() methods for the virtual table. All the
+** work is done in function fts5VocabInitVtab().
+*/
+static int fts5VocabConnectMethod(
+  sqlite3 *db,                    /* Database connection */
+  void *pAux,                     /* Pointer to tokenizer hash table */
+  int argc,                       /* Number of elements in argv array */
+  const char * const *argv,       /* xCreate/xConnect argument array */
+  sqlite3_vtab **ppVtab,          /* OUT: New sqlite3_vtab object */
+  char **pzErr                    /* OUT: sqlite3_malloc'd error message */
+){
+  return fts5VocabInitVtab(db, pAux, argc, argv, ppVtab, pzErr);
+}
+static int fts5VocabCreateMethod(
+  sqlite3 *db,                    /* Database connection */
+  void *pAux,                     /* Pointer to tokenizer hash table */
+  int argc,                       /* Number of elements in argv array */
+  const char * const *argv,       /* xCreate/xConnect argument array */
+  sqlite3_vtab **ppVtab,          /* OUT: New sqlite3_vtab object */
+  char **pzErr                    /* OUT: sqlite3_malloc'd error message */
+){
+  return fts5VocabInitVtab(db, pAux, argc, argv, ppVtab, pzErr);
+}
+
+/* 
+** Implementation of the xBestIndex method.
+*/
+static int fts5VocabBestIndexMethod(
+  sqlite3_vtab *pUnused,
+  sqlite3_index_info *pInfo
+){
+  int i;
+  int iTermEq = -1;
+  int iTermGe = -1;
+  int iTermLe = -1;
+  int idxNum = 0;
+  int nArg = 0;
+
+  UNUSED_PARAM(pUnused);
+
+  for(i=0; i<pInfo->nConstraint; i++){
+    struct sqlite3_index_constraint *p = &pInfo->aConstraint[i];
+    if( p->usable==0 ) continue;
+    if( p->iColumn==0 ){          /* term column */
+      if( p->op==SQLITE_INDEX_CONSTRAINT_EQ ) iTermEq = i;
+      if( p->op==SQLITE_INDEX_CONSTRAINT_LE ) iTermLe = i;
+      if( p->op==SQLITE_INDEX_CONSTRAINT_LT ) iTermLe = i;
+      if( p->op==SQLITE_INDEX_CONSTRAINT_GE ) iTermGe = i;
+      if( p->op==SQLITE_INDEX_CONSTRAINT_GT ) iTermGe = i;
+    }
+  }
+
+  if( iTermEq>=0 ){
+    idxNum |= FTS5_VOCAB_TERM_EQ;
+    pInfo->aConstraintUsage[iTermEq].argvIndex = ++nArg;
+    pInfo->estimatedCost = 100;
+  }else{
+    pInfo->estimatedCost = 1000000;
+    if( iTermGe>=0 ){
+      idxNum |= FTS5_VOCAB_TERM_GE;
+      pInfo->aConstraintUsage[iTermGe].argvIndex = ++nArg;
+      pInfo->estimatedCost = pInfo->estimatedCost / 2;
+    }
+    if( iTermLe>=0 ){
+      idxNum |= FTS5_VOCAB_TERM_LE;
+      pInfo->aConstraintUsage[iTermLe].argvIndex = ++nArg;
+      pInfo->estimatedCost = pInfo->estimatedCost / 2;
+    }
+  }
+
+  /* This virtual table always delivers results in ascending order of
+  ** the "term" column (column 0). So if the user has requested this
+  ** specifically - "ORDER BY term" or "ORDER BY term ASC" - set the
+  ** sqlite3_index_info.orderByConsumed flag to tell the core the results
+  ** are already in sorted order.  */
+  if( pInfo->nOrderBy==1 
+   && pInfo->aOrderBy[0].iColumn==0 
+   && pInfo->aOrderBy[0].desc==0
+  ){
+    pInfo->orderByConsumed = 1;
+  }
+
+  pInfo->idxNum = idxNum;
+  return SQLITE_OK;
+}
+
+/*
+** Implementation of xOpen method.
+*/
+static int fts5VocabOpenMethod(
+  sqlite3_vtab *pVTab, 
+  sqlite3_vtab_cursor **ppCsr
+){
+  Fts5VocabTable *pTab = (Fts5VocabTable*)pVTab;
+  Fts5Index *pIndex = 0;
+  Fts5Config *pConfig = 0;
+  Fts5VocabCursor *pCsr = 0;
+  int rc = SQLITE_OK;
+  sqlite3_stmt *pStmt = 0;
+  char *zSql = 0;
+
+  zSql = sqlite3Fts5Mprintf(&rc,
+      "SELECT t.%Q FROM %Q.%Q AS t WHERE t.%Q MATCH '*id'",
+      pTab->zFts5Tbl, pTab->zFts5Db, pTab->zFts5Tbl, pTab->zFts5Tbl
+  );
+  if( zSql ){
+    rc = sqlite3_prepare_v2(pTab->db, zSql, -1, &pStmt, 0);
+  }
+  sqlite3_free(zSql);
+  assert( rc==SQLITE_OK || pStmt==0 );
+  if( rc==SQLITE_ERROR ) rc = SQLITE_OK;
+
+  if( pStmt && sqlite3_step(pStmt)==SQLITE_ROW ){
+    i64 iId = sqlite3_column_int64(pStmt, 0);
+    pIndex = sqlite3Fts5IndexFromCsrid(pTab->pGlobal, iId, &pConfig);
+  }
+
+  if( rc==SQLITE_OK && pIndex==0 ){
+    rc = sqlite3_finalize(pStmt);
+    pStmt = 0;
+    if( rc==SQLITE_OK ){
+      pVTab->zErrMsg = sqlite3_mprintf(
+          "no such fts5 table: %s.%s", pTab->zFts5Db, pTab->zFts5Tbl
+      );
+      rc = SQLITE_ERROR;
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    int nByte = pConfig->nCol * sizeof(i64) * 2 + sizeof(Fts5VocabCursor);
+    pCsr = (Fts5VocabCursor*)sqlite3Fts5MallocZero(&rc, nByte);
+  }
+
+  if( pCsr ){
+    pCsr->pIndex = pIndex;
+    pCsr->pStmt = pStmt;
+    pCsr->pConfig = pConfig;
+    pCsr->aCnt = (i64*)&pCsr[1];
+    pCsr->aDoc = &pCsr->aCnt[pConfig->nCol];
+  }else{
+    sqlite3_finalize(pStmt);
+  }
+
+  *ppCsr = (sqlite3_vtab_cursor*)pCsr;
+  return rc;
+}
+
+static void fts5VocabResetCursor(Fts5VocabCursor *pCsr){
+  pCsr->rowid = 0;
+  sqlite3Fts5IterClose(pCsr->pIter);
+  pCsr->pIter = 0;
+  sqlite3_free(pCsr->zLeTerm);
+  pCsr->nLeTerm = -1;
+  pCsr->zLeTerm = 0;
+}
+
+/*
+** Close the cursor.  For additional information see the documentation
+** on the xClose method of the virtual table interface.
+*/
+static int fts5VocabCloseMethod(sqlite3_vtab_cursor *pCursor){
+  Fts5VocabCursor *pCsr = (Fts5VocabCursor*)pCursor;
+  fts5VocabResetCursor(pCsr);
+  sqlite3Fts5BufferFree(&pCsr->term);
+  sqlite3_finalize(pCsr->pStmt);
+  sqlite3_free(pCsr);
+  return SQLITE_OK;
+}
+
+
+/*
+** Advance the cursor to the next row in the table.
+*/
+static int fts5VocabNextMethod(sqlite3_vtab_cursor *pCursor){
+  Fts5VocabCursor *pCsr = (Fts5VocabCursor*)pCursor;
+  Fts5VocabTable *pTab = (Fts5VocabTable*)pCursor->pVtab;
+  int rc = SQLITE_OK;
+  int nCol = pCsr->pConfig->nCol;
+
+  pCsr->rowid++;
+
+  if( pTab->eType==FTS5_VOCAB_COL ){
+    for(pCsr->iCol++; pCsr->iCol<nCol; pCsr->iCol++){
+      if( pCsr->aDoc[pCsr->iCol] ) break;
+    }
+  }
+
+  if( pTab->eType==FTS5_VOCAB_ROW || pCsr->iCol>=nCol ){
+    if( sqlite3Fts5IterEof(pCsr->pIter) ){
+      pCsr->bEof = 1;
+    }else{
+      const char *zTerm;
+      int nTerm;
+
+      zTerm = sqlite3Fts5IterTerm(pCsr->pIter, &nTerm);
+      if( pCsr->nLeTerm>=0 ){
+        int nCmp = MIN(nTerm, pCsr->nLeTerm);
+        int bCmp = memcmp(pCsr->zLeTerm, zTerm, nCmp);
+        if( bCmp<0 || (bCmp==0 && pCsr->nLeTerm<nTerm) ){
+          pCsr->bEof = 1;
+          return SQLITE_OK;
+        }
+      }
+
+      sqlite3Fts5BufferSet(&rc, &pCsr->term, nTerm, (const u8*)zTerm);
+      memset(pCsr->aCnt, 0, nCol * sizeof(i64));
+      memset(pCsr->aDoc, 0, nCol * sizeof(i64));
+      pCsr->iCol = 0;
+
+      assert( pTab->eType==FTS5_VOCAB_COL || pTab->eType==FTS5_VOCAB_ROW );
+      while( rc==SQLITE_OK ){
+        const u8 *pPos; int nPos;   /* Position list */
+        i64 iPos = 0;               /* 64-bit position read from poslist */
+        int iOff = 0;               /* Current offset within position list */
+
+        pPos = pCsr->pIter->pData;
+        nPos = pCsr->pIter->nData;
+        switch( pCsr->pConfig->eDetail ){
+          case FTS5_DETAIL_FULL:
+            pPos = pCsr->pIter->pData;
+            nPos = pCsr->pIter->nData;
+            if( pTab->eType==FTS5_VOCAB_ROW ){
+              while( 0==sqlite3Fts5PoslistNext64(pPos, nPos, &iOff, &iPos) ){
+                pCsr->aCnt[0]++;
+              }
+              pCsr->aDoc[0]++;
+            }else{
+              int iCol = -1;
+              while( 0==sqlite3Fts5PoslistNext64(pPos, nPos, &iOff, &iPos) ){
+                int ii = FTS5_POS2COLUMN(iPos);
+                pCsr->aCnt[ii]++;
+                if( iCol!=ii ){
+                  if( ii>=nCol ){
+                    rc = FTS5_CORRUPT;
+                    break;
+                  }
+                  pCsr->aDoc[ii]++;
+                  iCol = ii;
+                }
+              }
+            }
+            break;
+
+          case FTS5_DETAIL_COLUMNS:
+            if( pTab->eType==FTS5_VOCAB_ROW ){
+              pCsr->aDoc[0]++;
+            }else{
+              while( 0==sqlite3Fts5PoslistNext64(pPos, nPos, &iOff,&iPos) ){
+                assert_nc( iPos>=0 && iPos<nCol );
+                if( iPos>=nCol ){
+                  rc = FTS5_CORRUPT;
+                  break;
+                }
+                pCsr->aDoc[iPos]++;
+              }
+            }
+            break;
+
+          default: 
+            assert( pCsr->pConfig->eDetail==FTS5_DETAIL_NONE );
+            pCsr->aDoc[0]++;
+            break;
+        }
+
+        if( rc==SQLITE_OK ){
+          rc = sqlite3Fts5IterNextScan(pCsr->pIter);
+        }
+
+        if( rc==SQLITE_OK ){
+          zTerm = sqlite3Fts5IterTerm(pCsr->pIter, &nTerm);
+          if( nTerm!=pCsr->term.n || memcmp(zTerm, pCsr->term.p, nTerm) ){
+            break;
+          }
+          if( sqlite3Fts5IterEof(pCsr->pIter) ) break;
+        }
+      }
+    }
+  }
+
+  if( rc==SQLITE_OK && pCsr->bEof==0 && pTab->eType==FTS5_VOCAB_COL ){
+    while( pCsr->aDoc[pCsr->iCol]==0 ) pCsr->iCol++;
+    assert( pCsr->iCol<pCsr->pConfig->nCol );
+  }
+  return rc;
+}
+
+/*
+** This is the xFilter implementation for the virtual table.
+*/
+static int fts5VocabFilterMethod(
+  sqlite3_vtab_cursor *pCursor,   /* The cursor used for this query */
+  int idxNum,                     /* Strategy index */
+  const char *zUnused,            /* Unused */
+  int nUnused,                    /* Number of elements in apVal */
+  sqlite3_value **apVal           /* Arguments for the indexing scheme */
+){
+  Fts5VocabCursor *pCsr = (Fts5VocabCursor*)pCursor;
+  int rc = SQLITE_OK;
+
+  int iVal = 0;
+  int f = FTS5INDEX_QUERY_SCAN;
+  const char *zTerm = 0;
+  int nTerm = 0;
+
+  sqlite3_value *pEq = 0;
+  sqlite3_value *pGe = 0;
+  sqlite3_value *pLe = 0;
+
+  UNUSED_PARAM2(zUnused, nUnused);
+
+  fts5VocabResetCursor(pCsr);
+  if( idxNum & FTS5_VOCAB_TERM_EQ ) pEq = apVal[iVal++];
+  if( idxNum & FTS5_VOCAB_TERM_GE ) pGe = apVal[iVal++];
+  if( idxNum & FTS5_VOCAB_TERM_LE ) pLe = apVal[iVal++];
+
+  if( pEq ){
+    zTerm = (const char *)sqlite3_value_text(pEq);
+    nTerm = sqlite3_value_bytes(pEq);
+    f = 0;
+  }else{
+    if( pGe ){
+      zTerm = (const char *)sqlite3_value_text(pGe);
+      nTerm = sqlite3_value_bytes(pGe);
+    }
+    if( pLe ){
+      const char *zCopy = (const char *)sqlite3_value_text(pLe);
+      pCsr->nLeTerm = sqlite3_value_bytes(pLe);
+      pCsr->zLeTerm = sqlite3_malloc(pCsr->nLeTerm+1);
+      if( pCsr->zLeTerm==0 ){
+        rc = SQLITE_NOMEM;
+      }else{
+        memcpy(pCsr->zLeTerm, zCopy, pCsr->nLeTerm+1);
+      }
+    }
+  }
+
+
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts5IndexQuery(pCsr->pIndex, zTerm, nTerm, f, 0, &pCsr->pIter);
+  }
+  if( rc==SQLITE_OK ){
+    rc = fts5VocabNextMethod(pCursor);
+  }
+
+  return rc;
+}
+
+/* 
+** This is the xEof method of the virtual table. SQLite calls this 
+** routine to find out if it has reached the end of a result set.
+*/
+static int fts5VocabEofMethod(sqlite3_vtab_cursor *pCursor){
+  Fts5VocabCursor *pCsr = (Fts5VocabCursor*)pCursor;
+  return pCsr->bEof;
+}
+
+static int fts5VocabColumnMethod(
+  sqlite3_vtab_cursor *pCursor,   /* Cursor to retrieve value from */
+  sqlite3_context *pCtx,          /* Context for sqlite3_result_xxx() calls */
+  int iCol                        /* Index of column to read value from */
+){
+  Fts5VocabCursor *pCsr = (Fts5VocabCursor*)pCursor;
+  int eDetail = pCsr->pConfig->eDetail;
+  int eType = ((Fts5VocabTable*)(pCursor->pVtab))->eType;
+  i64 iVal = 0;
+
+  if( iCol==0 ){
+    sqlite3_result_text(
+        pCtx, (const char*)pCsr->term.p, pCsr->term.n, SQLITE_TRANSIENT
+    );
+  }else if( eType==FTS5_VOCAB_COL ){
+    assert( iCol==1 || iCol==2 || iCol==3 );
+    if( iCol==1 ){
+      if( eDetail!=FTS5_DETAIL_NONE ){
+        const char *z = pCsr->pConfig->azCol[pCsr->iCol];
+        sqlite3_result_text(pCtx, z, -1, SQLITE_STATIC);
+      }
+    }else if( iCol==2 ){
+      iVal = pCsr->aDoc[pCsr->iCol];
+    }else{
+      iVal = pCsr->aCnt[pCsr->iCol];
+    }
+  }else{
+    assert( iCol==1 || iCol==2 );
+    if( iCol==1 ){
+      iVal = pCsr->aDoc[0];
+    }else{
+      iVal = pCsr->aCnt[0];
+    }
+  }
+
+  if( iVal>0 ) sqlite3_result_int64(pCtx, iVal);
+  return SQLITE_OK;
+}
+
+/* 
+** This is the xRowid method. The SQLite core calls this routine to
+** retrieve the rowid for the current row of the result set. The
+** rowid should be written to *pRowid.
+*/
+static int fts5VocabRowidMethod(
+  sqlite3_vtab_cursor *pCursor, 
+  sqlite_int64 *pRowid
+){
+  Fts5VocabCursor *pCsr = (Fts5VocabCursor*)pCursor;
+  *pRowid = pCsr->rowid;
+  return SQLITE_OK;
+}
+
+static int sqlite3Fts5VocabInit(Fts5Global *pGlobal, sqlite3 *db){
+  static const sqlite3_module fts5Vocab = {
+    /* iVersion      */ 2,
+    /* xCreate       */ fts5VocabCreateMethod,
+    /* xConnect      */ fts5VocabConnectMethod,
+    /* xBestIndex    */ fts5VocabBestIndexMethod,
+    /* xDisconnect   */ fts5VocabDisconnectMethod,
+    /* xDestroy      */ fts5VocabDestroyMethod,
+    /* xOpen         */ fts5VocabOpenMethod,
+    /* xClose        */ fts5VocabCloseMethod,
+    /* xFilter       */ fts5VocabFilterMethod,
+    /* xNext         */ fts5VocabNextMethod,
+    /* xEof          */ fts5VocabEofMethod,
+    /* xColumn       */ fts5VocabColumnMethod,
+    /* xRowid        */ fts5VocabRowidMethod,
+    /* xUpdate       */ 0,
+    /* xBegin        */ 0,
+    /* xSync         */ 0,
+    /* xCommit       */ 0,
+    /* xRollback     */ 0,
+    /* xFindFunction */ 0,
+    /* xRename       */ 0,
+    /* xSavepoint    */ 0,
+    /* xRelease      */ 0,
+    /* xRollbackTo   */ 0,
+  };
+  void *p = (void*)pGlobal;
+
+  return sqlite3_create_module_v2(db, "fts5vocab", &fts5Vocab, p, 0);
+}
+
+
+
+
+    
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS5) */
+
+/************** End of fts5.c ************************************************/
diff --git a/libs/tdlib/td/sqlite/sqlite/sqlite3.h b/libs/tdlib/td/sqlite/sqlite/sqlite3.h
new file mode 100644
index 0000000000..8222b7930e
--- /dev/null
+++ b/libs/tdlib/td/sqlite/sqlite/sqlite3.h
@@ -0,0 +1,10371 @@
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This header file defines the interface that the SQLite library
+** presents to client programs.  If a C-function, structure, datatype,
+** or constant definition does not appear in this file, then it is
+** not a published API of SQLite, is subject to change without
+** notice, and should not be referenced by programs that use SQLite.
+**
+** Some of the definitions that are in this file are marked as
+** "experimental".  Experimental interfaces are normally new
+** features recently added to SQLite.  We do not anticipate changes
+** to experimental interfaces but reserve the right to make minor changes
+** if experience from use "in the wild" suggest such changes are prudent.
+**
+** The official C-language API documentation for SQLite is derived
+** from comments in this file.  This file is the authoritative source
+** on how SQLite interfaces are supposed to operate.
+**
+** The name of this file under configuration management is "sqlite.h.in".
+** The makefile makes some minor changes to this file (such as inserting
+** the version number) and changes its name to "sqlite3.h" as
+** part of the build process.
+*/
+#ifndef SQLITE3_H
+#define SQLITE3_H
+#include <stdarg.h>     /* Needed for the definition of va_list */
+
+/*
+** Make sure we can call this stuff from C++.
+*/
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/*
+** Provide the ability to override linkage features of the interface.
+*/
+#ifndef SQLITE_EXTERN
+# define SQLITE_EXTERN extern
+#endif
+#ifndef SQLITE_API
+# define SQLITE_API
+#endif
+#ifndef SQLITE_CDECL
+# define SQLITE_CDECL
+#endif
+#ifndef SQLITE_APICALL
+# define SQLITE_APICALL
+#endif
+#ifndef SQLITE_STDCALL
+# define SQLITE_STDCALL SQLITE_APICALL
+#endif
+#ifndef SQLITE_CALLBACK
+# define SQLITE_CALLBACK
+#endif
+#ifndef SQLITE_SYSAPI
+# define SQLITE_SYSAPI
+#endif
+
+/*
+** These no-op macros are used in front of interfaces to mark those
+** interfaces as either deprecated or experimental.  New applications
+** should not use deprecated interfaces - they are supported for backwards
+** compatibility only.  Application writers should be aware that
+** experimental interfaces are subject to change in point releases.
+**
+** These macros used to resolve to various kinds of compiler magic that
+** would generate warning messages when they were used.  But that
+** compiler magic ended up generating such a flurry of bug reports
+** that we have taken it all out and gone back to using simple
+** noop macros.
+*/
+#define SQLITE_DEPRECATED
+#define SQLITE_EXPERIMENTAL
+
+/*
+** Ensure these symbols were not defined by some previous header file.
+*/
+#ifdef SQLITE_VERSION
+# undef SQLITE_VERSION
+#endif
+#ifdef SQLITE_VERSION_NUMBER
+# undef SQLITE_VERSION_NUMBER
+#endif
+
+/*
+** CAPI3REF: Compile-Time Library Version Numbers
+**
+** ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header
+** evaluates to a string literal that is the SQLite version in the
+** format "X.Y.Z" where X is the major version number (always 3 for
+** SQLite3) and Y is the minor version number and Z is the release number.)^
+** ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves to an integer
+** with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z are the same
+** numbers used in [SQLITE_VERSION].)^
+** The SQLITE_VERSION_NUMBER for any given release of SQLite will also
+** be larger than the release from which it is derived.  Either Y will
+** be held constant and Z will be incremented or else Y will be incremented
+** and Z will be reset to zero.
+**
+** Since [version 3.6.18] ([dateof:3.6.18]), 
+** SQLite source code has been stored in the
+** <a href="http://www.fossil-scm.org/">Fossil configuration management
+** system</a>.  ^The SQLITE_SOURCE_ID macro evaluates to
+** a string which identifies a particular check-in of SQLite
+** within its configuration management system.  ^The SQLITE_SOURCE_ID
+** string contains the date and time of the check-in (UTC) and an SHA1
+** hash of the entire source tree.
+**
+** See also: [sqlite3_libversion()],
+** [sqlite3_libversion_number()], [sqlite3_sourceid()],
+** [sqlite_version()] and [sqlite_source_id()].
+*/
+#define SQLITE_VERSION        "3.15.2"
+#define SQLITE_VERSION_NUMBER 3015002
+#define SQLITE_SOURCE_ID      "2016-11-28 19:13:37 bbd85d235f7037c6a033a9690534391ffeacecc8"
+
+/*
+** CAPI3REF: Run-Time Library Version Numbers
+** KEYWORDS: sqlite3_version, sqlite3_sourceid
+**
+** These interfaces provide the same information as the [SQLITE_VERSION],
+** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
+** but are associated with the library instead of the header file.  ^(Cautious
+** programmers might include assert() statements in their application to
+** verify that values returned by these interfaces match the macros in
+** the header, and thus ensure that the application is
+** compiled with matching library and header files.
+**
+** <blockquote><pre>
+** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );
+** assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 );
+** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );
+** </pre></blockquote>)^
+**
+** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION]
+** macro.  ^The sqlite3_libversion() function returns a pointer to the
+** to the sqlite3_version[] string constant.  The sqlite3_libversion()
+** function is provided for use in DLLs since DLL users usually do not have
+** direct access to string constants within the DLL.  ^The
+** sqlite3_libversion_number() function returns an integer equal to
+** [SQLITE_VERSION_NUMBER].  ^The sqlite3_sourceid() function returns 
+** a pointer to a string constant whose value is the same as the 
+** [SQLITE_SOURCE_ID] C preprocessor macro.
+**
+** See also: [sqlite_version()] and [sqlite_source_id()].
+*/
+SQLITE_API SQLITE_EXTERN const char sqlite3_version[];
+SQLITE_API const char *sqlite3_libversion(void);
+SQLITE_API const char *sqlite3_sourceid(void);
+SQLITE_API int sqlite3_libversion_number(void);
+
+/*
+** CAPI3REF: Run-Time Library Compilation Options Diagnostics
+**
+** ^The sqlite3_compileoption_used() function returns 0 or 1 
+** indicating whether the specified option was defined at 
+** compile time.  ^The SQLITE_ prefix may be omitted from the 
+** option name passed to sqlite3_compileoption_used().  
+**
+** ^The sqlite3_compileoption_get() function allows iterating
+** over the list of options that were defined at compile time by
+** returning the N-th compile time option string.  ^If N is out of range,
+** sqlite3_compileoption_get() returns a NULL pointer.  ^The SQLITE_ 
+** prefix is omitted from any strings returned by 
+** sqlite3_compileoption_get().
+**
+** ^Support for the diagnostic functions sqlite3_compileoption_used()
+** and sqlite3_compileoption_get() may be omitted by specifying the 
+** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time.
+**
+** See also: SQL functions [sqlite_compileoption_used()] and
+** [sqlite_compileoption_get()] and the [compile_options pragma].
+*/
+#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
+SQLITE_API int sqlite3_compileoption_used(const char *zOptName);
+SQLITE_API const char *sqlite3_compileoption_get(int N);
+#endif
+
+/*
+** CAPI3REF: Test To See If The Library Is Threadsafe
+**
+** ^The sqlite3_threadsafe() function returns zero if and only if
+** SQLite was compiled with mutexing code omitted due to the
+** [SQLITE_THREADSAFE] compile-time option being set to 0.
+**
+** SQLite can be compiled with or without mutexes.  When
+** the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes
+** are enabled and SQLite is threadsafe.  When the
+** [SQLITE_THREADSAFE] macro is 0, 
+** the mutexes are omitted.  Without the mutexes, it is not safe
+** to use SQLite concurrently from more than one thread.
+**
+** Enabling mutexes incurs a measurable performance penalty.
+** So if speed is of utmost importance, it makes sense to disable
+** the mutexes.  But for maximum safety, mutexes should be enabled.
+** ^The default behavior is for mutexes to be enabled.
+**
+** This interface can be used by an application to make sure that the
+** version of SQLite that it is linking against was compiled with
+** the desired setting of the [SQLITE_THREADSAFE] macro.
+**
+** This interface only reports on the compile-time mutex setting
+** of the [SQLITE_THREADSAFE] flag.  If SQLite is compiled with
+** SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but
+** can be fully or partially disabled using a call to [sqlite3_config()]
+** with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD],
+** or [SQLITE_CONFIG_SERIALIZED].  ^(The return value of the
+** sqlite3_threadsafe() function shows only the compile-time setting of
+** thread safety, not any run-time changes to that setting made by
+** sqlite3_config(). In other words, the return value from sqlite3_threadsafe()
+** is unchanged by calls to sqlite3_config().)^
+**
+** See the [threading mode] documentation for additional information.
+*/
+SQLITE_API int sqlite3_threadsafe(void);
+
+/*
+** CAPI3REF: Database Connection Handle
+** KEYWORDS: {database connection} {database connections}
+**
+** Each open SQLite database is represented by a pointer to an instance of
+** the opaque structure named "sqlite3".  It is useful to think of an sqlite3
+** pointer as an object.  The [sqlite3_open()], [sqlite3_open16()], and
+** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
+** and [sqlite3_close_v2()] are its destructors.  There are many other
+** interfaces (such as
+** [sqlite3_prepare_v2()], [sqlite3_create_function()], and
+** [sqlite3_busy_timeout()] to name but three) that are methods on an
+** sqlite3 object.
+*/
+typedef struct sqlite3 sqlite3;
+
+/*
+** CAPI3REF: 64-Bit Integer Types
+** KEYWORDS: sqlite_int64 sqlite_uint64
+**
+** Because there is no cross-platform way to specify 64-bit integer types
+** SQLite includes typedefs for 64-bit signed and unsigned integers.
+**
+** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.
+** The sqlite_int64 and sqlite_uint64 types are supported for backwards
+** compatibility only.
+**
+** ^The sqlite3_int64 and sqlite_int64 types can store integer values
+** between -9223372036854775808 and +9223372036854775807 inclusive.  ^The
+** sqlite3_uint64 and sqlite_uint64 types can store integer values 
+** between 0 and +18446744073709551615 inclusive.
+*/
+#ifdef SQLITE_INT64_TYPE
+  typedef SQLITE_INT64_TYPE sqlite_int64;
+  typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
+#elif defined(_MSC_VER) || defined(__BORLANDC__)
+  typedef __int64 sqlite_int64;
+  typedef unsigned __int64 sqlite_uint64;
+#else
+  typedef long long int sqlite_int64;
+  typedef unsigned long long int sqlite_uint64;
+#endif
+typedef sqlite_int64 sqlite3_int64;
+typedef sqlite_uint64 sqlite3_uint64;
+
+/*
+** If compiling for a processor that lacks floating point support,
+** substitute integer for floating-point.
+*/
+#ifdef SQLITE_OMIT_FLOATING_POINT
+# define double sqlite3_int64
+#endif
+
+/*
+** CAPI3REF: Closing A Database Connection
+** DESTRUCTOR: sqlite3
+**
+** ^The sqlite3_close() and sqlite3_close_v2() routines are destructors
+** for the [sqlite3] object.
+** ^Calls to sqlite3_close() and sqlite3_close_v2() return [SQLITE_OK] if
+** the [sqlite3] object is successfully destroyed and all associated
+** resources are deallocated.
+**
+** ^If the database connection is associated with unfinalized prepared
+** statements or unfinished sqlite3_backup objects then sqlite3_close()
+** will leave the database connection open and return [SQLITE_BUSY].
+** ^If sqlite3_close_v2() is called with unfinalized prepared statements
+** and/or unfinished sqlite3_backups, then the database connection becomes
+** an unusable "zombie" which will automatically be deallocated when the
+** last prepared statement is finalized or the last sqlite3_backup is
+** finished.  The sqlite3_close_v2() interface is intended for use with
+** host languages that are garbage collected, and where the order in which
+** destructors are called is arbitrary.
+**
+** Applications should [sqlite3_finalize | finalize] all [prepared statements],
+** [sqlite3_blob_close | close] all [BLOB handles], and 
+** [sqlite3_backup_finish | finish] all [sqlite3_backup] objects associated
+** with the [sqlite3] object prior to attempting to close the object.  ^If
+** sqlite3_close_v2() is called on a [database connection] that still has
+** outstanding [prepared statements], [BLOB handles], and/or
+** [sqlite3_backup] objects then it returns [SQLITE_OK] and the deallocation
+** of resources is deferred until all [prepared statements], [BLOB handles],
+** and [sqlite3_backup] objects are also destroyed.
+**
+** ^If an [sqlite3] object is destroyed while a transaction is open,
+** the transaction is automatically rolled back.
+**
+** The C parameter to [sqlite3_close(C)] and [sqlite3_close_v2(C)]
+** must be either a NULL
+** pointer or an [sqlite3] object pointer obtained
+** from [sqlite3_open()], [sqlite3_open16()], or
+** [sqlite3_open_v2()], and not previously closed.
+** ^Calling sqlite3_close() or sqlite3_close_v2() with a NULL pointer
+** argument is a harmless no-op.
+*/
+SQLITE_API int sqlite3_close(sqlite3*);
+SQLITE_API int sqlite3_close_v2(sqlite3*);
+
+/*
+** The type for a callback function.
+** This is legacy and deprecated.  It is included for historical
+** compatibility and is not documented.
+*/
+typedef int (*sqlite3_callback)(void*,int,char**, char**);
+
+/*
+** CAPI3REF: One-Step Query Execution Interface
+** METHOD: sqlite3
+**
+** The sqlite3_exec() interface is a convenience wrapper around
+** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()],
+** that allows an application to run multiple statements of SQL
+** without having to use a lot of C code. 
+**
+** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
+** semicolon-separate SQL statements passed into its 2nd argument,
+** in the context of the [database connection] passed in as its 1st
+** argument.  ^If the callback function of the 3rd argument to
+** sqlite3_exec() is not NULL, then it is invoked for each result row
+** coming out of the evaluated SQL statements.  ^The 4th argument to
+** sqlite3_exec() is relayed through to the 1st argument of each
+** callback invocation.  ^If the callback pointer to sqlite3_exec()
+** is NULL, then no callback is ever invoked and result rows are
+** ignored.
+**
+** ^If an error occurs while evaluating the SQL statements passed into
+** sqlite3_exec(), then execution of the current statement stops and
+** subsequent statements are skipped.  ^If the 5th parameter to sqlite3_exec()
+** is not NULL then any error message is written into memory obtained
+** from [sqlite3_malloc()] and passed back through the 5th parameter.
+** To avoid memory leaks, the application should invoke [sqlite3_free()]
+** on error message strings returned through the 5th parameter of
+** sqlite3_exec() after the error message string is no longer needed.
+** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors
+** occur, then sqlite3_exec() sets the pointer in its 5th parameter to
+** NULL before returning.
+**
+** ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec()
+** routine returns SQLITE_ABORT without invoking the callback again and
+** without running any subsequent SQL statements.
+**
+** ^The 2nd argument to the sqlite3_exec() callback function is the
+** number of columns in the result.  ^The 3rd argument to the sqlite3_exec()
+** callback is an array of pointers to strings obtained as if from
+** [sqlite3_column_text()], one for each column.  ^If an element of a
+** result row is NULL then the corresponding string pointer for the
+** sqlite3_exec() callback is a NULL pointer.  ^The 4th argument to the
+** sqlite3_exec() callback is an array of pointers to strings where each
+** entry represents the name of corresponding result column as obtained
+** from [sqlite3_column_name()].
+**
+** ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer
+** to an empty string, or a pointer that contains only whitespace and/or 
+** SQL comments, then no SQL statements are evaluated and the database
+** is not changed.
+**
+** Restrictions:
+**
+** <ul>
+** <li> The application must ensure that the 1st parameter to sqlite3_exec()
+**      is a valid and open [database connection].
+** <li> The application must not close the [database connection] specified by
+**      the 1st parameter to sqlite3_exec() while sqlite3_exec() is running.
+** <li> The application must not modify the SQL statement text passed into
+**      the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running.
+** </ul>
+*/
+SQLITE_API int sqlite3_exec(
+  sqlite3*,                                  /* An open database */
+  const char *sql,                           /* SQL to be evaluated */
+  int (*callback)(void*,int,char**,char**),  /* Callback function */
+  void *,                                    /* 1st argument to callback */
+  char **errmsg                              /* Error msg written here */
+);
+
+/*
+** CAPI3REF: Result Codes
+** KEYWORDS: {result code definitions}
+**
+** Many SQLite functions return an integer result code from the set shown
+** here in order to indicate success or failure.
+**
+** New error codes may be added in future versions of SQLite.
+**
+** See also: [extended result code definitions]
+*/
+#define SQLITE_OK           0   /* Successful result */
+/* beginning-of-error-codes */
+#define SQLITE_ERROR        1   /* SQL error or missing database */
+#define SQLITE_INTERNAL     2   /* Internal logic error in SQLite */
+#define SQLITE_PERM         3   /* Access permission denied */
+#define SQLITE_ABORT        4   /* Callback routine requested an abort */
+#define SQLITE_BUSY         5   /* The database file is locked */
+#define SQLITE_LOCKED       6   /* A table in the database is locked */
+#define SQLITE_NOMEM        7   /* A malloc() failed */
+#define SQLITE_READONLY     8   /* Attempt to write a readonly database */
+#define SQLITE_INTERRUPT    9   /* Operation terminated by sqlite3_interrupt()*/
+#define SQLITE_IOERR       10   /* Some kind of disk I/O error occurred */
+#define SQLITE_CORRUPT     11   /* The database disk image is malformed */
+#define SQLITE_NOTFOUND    12   /* Unknown opcode in sqlite3_file_control() */
+#define SQLITE_FULL        13   /* Insertion failed because database is full */
+#define SQLITE_CANTOPEN    14   /* Unable to open the database file */
+#define SQLITE_PROTOCOL    15   /* Database lock protocol error */
+#define SQLITE_EMPTY       16   /* Database is empty */
+#define SQLITE_SCHEMA      17   /* The database schema changed */
+#define SQLITE_TOOBIG      18   /* String or BLOB exceeds size limit */
+#define SQLITE_CONSTRAINT  19   /* Abort due to constraint violation */
+#define SQLITE_MISMATCH    20   /* Data type mismatch */
+#define SQLITE_MISUSE      21   /* Library used incorrectly */
+#define SQLITE_NOLFS       22   /* Uses OS features not supported on host */
+#define SQLITE_AUTH        23   /* Authorization denied */
+#define SQLITE_FORMAT      24   /* Auxiliary database format error */
+#define SQLITE_RANGE       25   /* 2nd parameter to sqlite3_bind out of range */
+#define SQLITE_NOTADB      26   /* File opened that is not a database file */
+#define SQLITE_NOTICE      27   /* Notifications from sqlite3_log() */
+#define SQLITE_WARNING     28   /* Warnings from sqlite3_log() */
+#define SQLITE_ROW         100  /* sqlite3_step() has another row ready */
+#define SQLITE_DONE        101  /* sqlite3_step() has finished executing */
+/* end-of-error-codes */
+
+/*
+** CAPI3REF: Extended Result Codes
+** KEYWORDS: {extended result code definitions}
+**
+** In its default configuration, SQLite API routines return one of 30 integer
+** [result codes].  However, experience has shown that many of
+** these result codes are too coarse-grained.  They do not provide as
+** much information about problems as programmers might like.  In an effort to
+** address this, newer versions of SQLite (version 3.3.8 [dateof:3.3.8]
+** and later) include
+** support for additional result codes that provide more detailed information
+** about errors. These [extended result codes] are enabled or disabled
+** on a per database connection basis using the
+** [sqlite3_extended_result_codes()] API.  Or, the extended code for
+** the most recent error can be obtained using
+** [sqlite3_extended_errcode()].
+*/
+#define SQLITE_IOERR_READ              (SQLITE_IOERR | (1<<8))
+#define SQLITE_IOERR_SHORT_READ        (SQLITE_IOERR | (2<<8))
+#define SQLITE_IOERR_WRITE             (SQLITE_IOERR | (3<<8))
+#define SQLITE_IOERR_FSYNC             (SQLITE_IOERR | (4<<8))
+#define SQLITE_IOERR_DIR_FSYNC         (SQLITE_IOERR | (5<<8))
+#define SQLITE_IOERR_TRUNCATE          (SQLITE_IOERR | (6<<8))
+#define SQLITE_IOERR_FSTAT             (SQLITE_IOERR | (7<<8))
+#define SQLITE_IOERR_UNLOCK            (SQLITE_IOERR | (8<<8))
+#define SQLITE_IOERR_RDLOCK            (SQLITE_IOERR | (9<<8))
+#define SQLITE_IOERR_DELETE            (SQLITE_IOERR | (10<<8))
+#define SQLITE_IOERR_BLOCKED           (SQLITE_IOERR | (11<<8))
+#define SQLITE_IOERR_NOMEM             (SQLITE_IOERR | (12<<8))
+#define SQLITE_IOERR_ACCESS            (SQLITE_IOERR | (13<<8))
+#define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))
+#define SQLITE_IOERR_LOCK              (SQLITE_IOERR | (15<<8))
+#define SQLITE_IOERR_CLOSE             (SQLITE_IOERR | (16<<8))
+#define SQLITE_IOERR_DIR_CLOSE         (SQLITE_IOERR | (17<<8))
+#define SQLITE_IOERR_SHMOPEN           (SQLITE_IOERR | (18<<8))
+#define SQLITE_IOERR_SHMSIZE           (SQLITE_IOERR | (19<<8))
+#define SQLITE_IOERR_SHMLOCK           (SQLITE_IOERR | (20<<8))
+#define SQLITE_IOERR_SHMMAP            (SQLITE_IOERR | (21<<8))
+#define SQLITE_IOERR_SEEK              (SQLITE_IOERR | (22<<8))
+#define SQLITE_IOERR_DELETE_NOENT      (SQLITE_IOERR | (23<<8))
+#define SQLITE_IOERR_MMAP              (SQLITE_IOERR | (24<<8))
+#define SQLITE_IOERR_GETTEMPPATH       (SQLITE_IOERR | (25<<8))
+#define SQLITE_IOERR_CONVPATH          (SQLITE_IOERR | (26<<8))
+#define SQLITE_IOERR_VNODE             (SQLITE_IOERR | (27<<8))
+#define SQLITE_IOERR_AUTH              (SQLITE_IOERR | (28<<8))
+#define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
+#define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
+#define SQLITE_BUSY_SNAPSHOT           (SQLITE_BUSY   |  (2<<8))
+#define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
+#define SQLITE_CANTOPEN_ISDIR          (SQLITE_CANTOPEN | (2<<8))
+#define SQLITE_CANTOPEN_FULLPATH       (SQLITE_CANTOPEN | (3<<8))
+#define SQLITE_CANTOPEN_CONVPATH       (SQLITE_CANTOPEN | (4<<8))
+#define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))
+#define SQLITE_READONLY_RECOVERY       (SQLITE_READONLY | (1<<8))
+#define SQLITE_READONLY_CANTLOCK       (SQLITE_READONLY | (2<<8))
+#define SQLITE_READONLY_ROLLBACK       (SQLITE_READONLY | (3<<8))
+#define SQLITE_READONLY_DBMOVED        (SQLITE_READONLY | (4<<8))
+#define SQLITE_ABORT_ROLLBACK          (SQLITE_ABORT | (2<<8))
+#define SQLITE_CONSTRAINT_CHECK        (SQLITE_CONSTRAINT | (1<<8))
+#define SQLITE_CONSTRAINT_COMMITHOOK   (SQLITE_CONSTRAINT | (2<<8))
+#define SQLITE_CONSTRAINT_FOREIGNKEY   (SQLITE_CONSTRAINT | (3<<8))
+#define SQLITE_CONSTRAINT_FUNCTION     (SQLITE_CONSTRAINT | (4<<8))
+#define SQLITE_CONSTRAINT_NOTNULL      (SQLITE_CONSTRAINT | (5<<8))
+#define SQLITE_CONSTRAINT_PRIMARYKEY   (SQLITE_CONSTRAINT | (6<<8))
+#define SQLITE_CONSTRAINT_TRIGGER      (SQLITE_CONSTRAINT | (7<<8))
+#define SQLITE_CONSTRAINT_UNIQUE       (SQLITE_CONSTRAINT | (8<<8))
+#define SQLITE_CONSTRAINT_VTAB         (SQLITE_CONSTRAINT | (9<<8))
+#define SQLITE_CONSTRAINT_ROWID        (SQLITE_CONSTRAINT |(10<<8))
+#define SQLITE_NOTICE_RECOVER_WAL      (SQLITE_NOTICE | (1<<8))
+#define SQLITE_NOTICE_RECOVER_ROLLBACK (SQLITE_NOTICE | (2<<8))
+#define SQLITE_WARNING_AUTOINDEX       (SQLITE_WARNING | (1<<8))
+#define SQLITE_AUTH_USER               (SQLITE_AUTH | (1<<8))
+#define SQLITE_OK_LOAD_PERMANENTLY     (SQLITE_OK | (1<<8))
+
+/*
+** CAPI3REF: Flags For File Open Operations
+**
+** These bit values are intended for use in the
+** 3rd parameter to the [sqlite3_open_v2()] interface and
+** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
+*/
+#define SQLITE_OPEN_READONLY         0x00000001  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_READWRITE        0x00000002  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_CREATE           0x00000004  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_DELETEONCLOSE    0x00000008  /* VFS only */
+#define SQLITE_OPEN_EXCLUSIVE        0x00000010  /* VFS only */
+#define SQLITE_OPEN_AUTOPROXY        0x00000020  /* VFS only */
+#define SQLITE_OPEN_URI              0x00000040  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_MEMORY           0x00000080  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_MAIN_DB          0x00000100  /* VFS only */
+#define SQLITE_OPEN_TEMP_DB          0x00000200  /* VFS only */
+#define SQLITE_OPEN_TRANSIENT_DB     0x00000400  /* VFS only */
+#define SQLITE_OPEN_MAIN_JOURNAL     0x00000800  /* VFS only */
+#define SQLITE_OPEN_TEMP_JOURNAL     0x00001000  /* VFS only */
+#define SQLITE_OPEN_SUBJOURNAL       0x00002000  /* VFS only */
+#define SQLITE_OPEN_MASTER_JOURNAL   0x00004000  /* VFS only */
+#define SQLITE_OPEN_NOMUTEX          0x00008000  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_FULLMUTEX        0x00010000  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_SHAREDCACHE      0x00020000  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_PRIVATECACHE     0x00040000  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_WAL              0x00080000  /* VFS only */
+
+/* Reserved:                         0x00F00000 */
+
+/*
+** CAPI3REF: Device Characteristics
+**
+** The xDeviceCharacteristics method of the [sqlite3_io_methods]
+** object returns an integer which is a vector of these
+** bit values expressing I/O characteristics of the mass storage
+** device that holds the file that the [sqlite3_io_methods]
+** refers to.
+**
+** The SQLITE_IOCAP_ATOMIC property means that all writes of
+** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
+** mean that writes of blocks that are nnn bytes in size and
+** are aligned to an address which is an integer multiple of
+** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
+** that when data is appended to a file, the data is appended
+** first then the size of the file is extended, never the other
+** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
+** information is written to disk in the same order as calls
+** to xWrite().  The SQLITE_IOCAP_POWERSAFE_OVERWRITE property means that
+** after reboot following a crash or power loss, the only bytes in a
+** file that were written at the application level might have changed
+** and that adjacent bytes, even bytes within the same sector are
+** guaranteed to be unchanged.  The SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
+** flag indicate that a file cannot be deleted when open.  The
+** SQLITE_IOCAP_IMMUTABLE flag indicates that the file is on
+** read-only media and cannot be changed even by processes with
+** elevated privileges.
+*/
+#define SQLITE_IOCAP_ATOMIC                 0x00000001
+#define SQLITE_IOCAP_ATOMIC512              0x00000002
+#define SQLITE_IOCAP_ATOMIC1K               0x00000004
+#define SQLITE_IOCAP_ATOMIC2K               0x00000008
+#define SQLITE_IOCAP_ATOMIC4K               0x00000010
+#define SQLITE_IOCAP_ATOMIC8K               0x00000020
+#define SQLITE_IOCAP_ATOMIC16K              0x00000040
+#define SQLITE_IOCAP_ATOMIC32K              0x00000080
+#define SQLITE_IOCAP_ATOMIC64K              0x00000100
+#define SQLITE_IOCAP_SAFE_APPEND            0x00000200
+#define SQLITE_IOCAP_SEQUENTIAL             0x00000400
+#define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN  0x00000800
+#define SQLITE_IOCAP_POWERSAFE_OVERWRITE    0x00001000
+#define SQLITE_IOCAP_IMMUTABLE              0x00002000
+
+/*
+** CAPI3REF: File Locking Levels
+**
+** SQLite uses one of these integer values as the second
+** argument to calls it makes to the xLock() and xUnlock() methods
+** of an [sqlite3_io_methods] object.
+*/
+#define SQLITE_LOCK_NONE          0
+#define SQLITE_LOCK_SHARED        1
+#define SQLITE_LOCK_RESERVED      2
+#define SQLITE_LOCK_PENDING       3
+#define SQLITE_LOCK_EXCLUSIVE     4
+
+/*
+** CAPI3REF: Synchronization Type Flags
+**
+** When SQLite invokes the xSync() method of an
+** [sqlite3_io_methods] object it uses a combination of
+** these integer values as the second argument.
+**
+** When the SQLITE_SYNC_DATAONLY flag is used, it means that the
+** sync operation only needs to flush data to mass storage.  Inode
+** information need not be flushed. If the lower four bits of the flag
+** equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics.
+** If the lower four bits equal SQLITE_SYNC_FULL, that means
+** to use Mac OS X style fullsync instead of fsync().
+**
+** Do not confuse the SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags
+** with the [PRAGMA synchronous]=NORMAL and [PRAGMA synchronous]=FULL
+** settings.  The [synchronous pragma] determines when calls to the
+** xSync VFS method occur and applies uniformly across all platforms.
+** The SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags determine how
+** energetic or rigorous or forceful the sync operations are and
+** only make a difference on Mac OSX for the default SQLite code.
+** (Third-party VFS implementations might also make the distinction
+** between SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL, but among the
+** operating systems natively supported by SQLite, only Mac OSX
+** cares about the difference.)
+*/
+#define SQLITE_SYNC_NORMAL        0x00002
+#define SQLITE_SYNC_FULL          0x00003
+#define SQLITE_SYNC_DATAONLY      0x00010
+
+/*
+** CAPI3REF: OS Interface Open File Handle
+**
+** An [sqlite3_file] object represents an open file in the 
+** [sqlite3_vfs | OS interface layer].  Individual OS interface
+** implementations will
+** want to subclass this object by appending additional fields
+** for their own use.  The pMethods entry is a pointer to an
+** [sqlite3_io_methods] object that defines methods for performing
+** I/O operations on the open file.
+*/
+typedef struct sqlite3_file sqlite3_file;
+struct sqlite3_file {
+  const struct sqlite3_io_methods *pMethods;  /* Methods for an open file */
+};
+
+/*
+** CAPI3REF: OS Interface File Virtual Methods Object
+**
+** Every file opened by the [sqlite3_vfs.xOpen] method populates an
+** [sqlite3_file] object (or, more commonly, a subclass of the
+** [sqlite3_file] object) with a pointer to an instance of this object.
+** This object defines the methods used to perform various operations
+** against the open file represented by the [sqlite3_file] object.
+**
+** If the [sqlite3_vfs.xOpen] method sets the sqlite3_file.pMethods element 
+** to a non-NULL pointer, then the sqlite3_io_methods.xClose method
+** may be invoked even if the [sqlite3_vfs.xOpen] reported that it failed.  The
+** only way to prevent a call to xClose following a failed [sqlite3_vfs.xOpen]
+** is for the [sqlite3_vfs.xOpen] to set the sqlite3_file.pMethods element
+** to NULL.
+**
+** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or
+** [SQLITE_SYNC_FULL].  The first choice is the normal fsync().
+** The second choice is a Mac OS X style fullsync.  The [SQLITE_SYNC_DATAONLY]
+** flag may be ORed in to indicate that only the data of the file
+** and not its inode needs to be synced.
+**
+** The integer values to xLock() and xUnlock() are one of
+** <ul>
+** <li> [SQLITE_LOCK_NONE],
+** <li> [SQLITE_LOCK_SHARED],
+** <li> [SQLITE_LOCK_RESERVED],
+** <li> [SQLITE_LOCK_PENDING], or
+** <li> [SQLITE_LOCK_EXCLUSIVE].
+** </ul>
+** xLock() increases the lock. xUnlock() decreases the lock.
+** The xCheckReservedLock() method checks whether any database connection,
+** either in this process or in some other process, is holding a RESERVED,
+** PENDING, or EXCLUSIVE lock on the file.  It returns true
+** if such a lock exists and false otherwise.
+**
+** The xFileControl() method is a generic interface that allows custom
+** VFS implementations to directly control an open file using the
+** [sqlite3_file_control()] interface.  The second "op" argument is an
+** integer opcode.  The third argument is a generic pointer intended to
+** point to a structure that may contain arguments or space in which to
+** write return values.  Potential uses for xFileControl() might be
+** functions to enable blocking locks with timeouts, to change the
+** locking strategy (for example to use dot-file locks), to inquire
+** about the status of a lock, or to break stale locks.  The SQLite
+** core reserves all opcodes less than 100 for its own use.
+** A [file control opcodes | list of opcodes] less than 100 is available.
+** Applications that define a custom xFileControl method should use opcodes
+** greater than 100 to avoid conflicts.  VFS implementations should
+** return [SQLITE_NOTFOUND] for file control opcodes that they do not
+** recognize.
+**
+** The xSectorSize() method returns the sector size of the
+** device that underlies the file.  The sector size is the
+** minimum write that can be performed without disturbing
+** other bytes in the file.  The xDeviceCharacteristics()
+** method returns a bit vector describing behaviors of the
+** underlying device:
+**
+** <ul>
+** <li> [SQLITE_IOCAP_ATOMIC]
+** <li> [SQLITE_IOCAP_ATOMIC512]
+** <li> [SQLITE_IOCAP_ATOMIC1K]
+** <li> [SQLITE_IOCAP_ATOMIC2K]
+** <li> [SQLITE_IOCAP_ATOMIC4K]
+** <li> [SQLITE_IOCAP_ATOMIC8K]
+** <li> [SQLITE_IOCAP_ATOMIC16K]
+** <li> [SQLITE_IOCAP_ATOMIC32K]
+** <li> [SQLITE_IOCAP_ATOMIC64K]
+** <li> [SQLITE_IOCAP_SAFE_APPEND]
+** <li> [SQLITE_IOCAP_SEQUENTIAL]
+** </ul>
+**
+** The SQLITE_IOCAP_ATOMIC property means that all writes of
+** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
+** mean that writes of blocks that are nnn bytes in size and
+** are aligned to an address which is an integer multiple of
+** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
+** that when data is appended to a file, the data is appended
+** first then the size of the file is extended, never the other
+** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
+** information is written to disk in the same order as calls
+** to xWrite().
+**
+** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill
+** in the unread portions of the buffer with zeros.  A VFS that
+** fails to zero-fill short reads might seem to work.  However,
+** failure to zero-fill short reads will eventually lead to
+** database corruption.
+*/
+typedef struct sqlite3_io_methods sqlite3_io_methods;
+struct sqlite3_io_methods {
+  int iVersion;
+  int (*xClose)(sqlite3_file*);
+  int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
+  int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
+  int (*xTruncate)(sqlite3_file*, sqlite3_int64 size);
+  int (*xSync)(sqlite3_file*, int flags);
+  int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize);
+  int (*xLock)(sqlite3_file*, int);
+  int (*xUnlock)(sqlite3_file*, int);
+  int (*xCheckReservedLock)(sqlite3_file*, int *pResOut);
+  int (*xFileControl)(sqlite3_file*, int op, void *pArg);
+  int (*xSectorSize)(sqlite3_file*);
+  int (*xDeviceCharacteristics)(sqlite3_file*);
+  /* Methods above are valid for version 1 */
+  int (*xShmMap)(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
+  int (*xShmLock)(sqlite3_file*, int offset, int n, int flags);
+  void (*xShmBarrier)(sqlite3_file*);
+  int (*xShmUnmap)(sqlite3_file*, int deleteFlag);
+  /* Methods above are valid for version 2 */
+  int (*xFetch)(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
+  int (*xUnfetch)(sqlite3_file*, sqlite3_int64 iOfst, void *p);
+  /* Methods above are valid for version 3 */
+  /* Additional methods may be added in future releases */
+};
+
+/*
+** CAPI3REF: Standard File Control Opcodes
+** KEYWORDS: {file control opcodes} {file control opcode}
+**
+** These integer constants are opcodes for the xFileControl method
+** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]
+** interface.
+**
+** <ul>
+** <li>[[SQLITE_FCNTL_LOCKSTATE]]
+** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging.  This
+** opcode causes the xFileControl method to write the current state of
+** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
+** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
+** into an integer that the pArg argument points to. This capability
+** is used during testing and is only available when the SQLITE_TEST
+** compile-time option is used.
+**
+** <li>[[SQLITE_FCNTL_SIZE_HINT]]
+** The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS
+** layer a hint of how large the database file will grow to be during the
+** current transaction.  This hint is not guaranteed to be accurate but it
+** is often close.  The underlying VFS might choose to preallocate database
+** file space based on this hint in order to help writes to the database
+** file run faster.
+**
+** <li>[[SQLITE_FCNTL_CHUNK_SIZE]]
+** The [SQLITE_FCNTL_CHUNK_SIZE] opcode is used to request that the VFS
+** extends and truncates the database file in chunks of a size specified
+** by the user. The fourth argument to [sqlite3_file_control()] should 
+** point to an integer (type int) containing the new chunk-size to use
+** for the nominated database. Allocating database file space in large
+** chunks (say 1MB at a time), may reduce file-system fragmentation and
+** improve performance on some systems.
+**
+** <li>[[SQLITE_FCNTL_FILE_POINTER]]
+** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer
+** to the [sqlite3_file] object associated with a particular database
+** connection.  See also [SQLITE_FCNTL_JOURNAL_POINTER].
+**
+** <li>[[SQLITE_FCNTL_JOURNAL_POINTER]]
+** The [SQLITE_FCNTL_JOURNAL_POINTER] opcode is used to obtain a pointer
+** to the [sqlite3_file] object associated with the journal file (either
+** the [rollback journal] or the [write-ahead log]) for a particular database
+** connection.  See also [SQLITE_FCNTL_FILE_POINTER].
+**
+** <li>[[SQLITE_FCNTL_SYNC_OMITTED]]
+** No longer in use.
+**
+** <li>[[SQLITE_FCNTL_SYNC]]
+** The [SQLITE_FCNTL_SYNC] opcode is generated internally by SQLite and
+** sent to the VFS immediately before the xSync method is invoked on a
+** database file descriptor. Or, if the xSync method is not invoked 
+** because the user has configured SQLite with 
+** [PRAGMA synchronous | PRAGMA synchronous=OFF] it is invoked in place 
+** of the xSync method. In most cases, the pointer argument passed with
+** this file-control is NULL. However, if the database file is being synced
+** as part of a multi-database commit, the argument points to a nul-terminated
+** string containing the transactions master-journal file name. VFSes that 
+** do not need this signal should silently ignore this opcode. Applications 
+** should not call [sqlite3_file_control()] with this opcode as doing so may 
+** disrupt the operation of the specialized VFSes that do require it.  
+**
+** <li>[[SQLITE_FCNTL_COMMIT_PHASETWO]]
+** The [SQLITE_FCNTL_COMMIT_PHASETWO] opcode is generated internally by SQLite
+** and sent to the VFS after a transaction has been committed immediately
+** but before the database is unlocked. VFSes that do not need this signal
+** should silently ignore this opcode. Applications should not call
+** [sqlite3_file_control()] with this opcode as doing so may disrupt the 
+** operation of the specialized VFSes that do require it.  
+**
+** <li>[[SQLITE_FCNTL_WIN32_AV_RETRY]]
+** ^The [SQLITE_FCNTL_WIN32_AV_RETRY] opcode is used to configure automatic
+** retry counts and intervals for certain disk I/O operations for the
+** windows [VFS] in order to provide robustness in the presence of
+** anti-virus programs.  By default, the windows VFS will retry file read,
+** file write, and file delete operations up to 10 times, with a delay
+** of 25 milliseconds before the first retry and with the delay increasing
+** by an additional 25 milliseconds with each subsequent retry.  This
+** opcode allows these two values (10 retries and 25 milliseconds of delay)
+** to be adjusted.  The values are changed for all database connections
+** within the same process.  The argument is a pointer to an array of two
+** integers where the first integer i the new retry count and the second
+** integer is the delay.  If either integer is negative, then the setting
+** is not changed but instead the prior value of that setting is written
+** into the array entry, allowing the current retry settings to be
+** interrogated.  The zDbName parameter is ignored.
+**
+** <li>[[SQLITE_FCNTL_PERSIST_WAL]]
+** ^The [SQLITE_FCNTL_PERSIST_WAL] opcode is used to set or query the
+** persistent [WAL | Write Ahead Log] setting.  By default, the auxiliary
+** write ahead log and shared memory files used for transaction control
+** are automatically deleted when the latest connection to the database
+** closes.  Setting persistent WAL mode causes those files to persist after
+** close.  Persisting the files is useful when other processes that do not
+** have write permission on the directory containing the database file want
+** to read the database file, as the WAL and shared memory files must exist
+** in order for the database to be readable.  The fourth parameter to
+** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
+** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
+** WAL mode.  If the integer is -1, then it is overwritten with the current
+** WAL persistence setting.
+**
+** <li>[[SQLITE_FCNTL_POWERSAFE_OVERWRITE]]
+** ^The [SQLITE_FCNTL_POWERSAFE_OVERWRITE] opcode is used to set or query the
+** persistent "powersafe-overwrite" or "PSOW" setting.  The PSOW setting
+** determines the [SQLITE_IOCAP_POWERSAFE_OVERWRITE] bit of the
+** xDeviceCharacteristics methods. The fourth parameter to
+** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
+** That integer is 0 to disable zero-damage mode or 1 to enable zero-damage
+** mode.  If the integer is -1, then it is overwritten with the current
+** zero-damage mode setting.
+**
+** <li>[[SQLITE_FCNTL_OVERWRITE]]
+** ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening
+** a write transaction to indicate that, unless it is rolled back for some
+** reason, the entire database file will be overwritten by the current 
+** transaction. This is used by VACUUM operations.
+**
+** <li>[[SQLITE_FCNTL_VFSNAME]]
+** ^The [SQLITE_FCNTL_VFSNAME] opcode can be used to obtain the names of
+** all [VFSes] in the VFS stack.  The names are of all VFS shims and the
+** final bottom-level VFS are written into memory obtained from 
+** [sqlite3_malloc()] and the result is stored in the char* variable
+** that the fourth parameter of [sqlite3_file_control()] points to.
+** The caller is responsible for freeing the memory when done.  As with
+** all file-control actions, there is no guarantee that this will actually
+** do anything.  Callers should initialize the char* variable to a NULL
+** pointer in case this file-control is not implemented.  This file-control
+** is intended for diagnostic use only.
+**
+** <li>[[SQLITE_FCNTL_VFS_POINTER]]
+** ^The [SQLITE_FCNTL_VFS_POINTER] opcode finds a pointer to the top-level
+** [VFSes] currently in use.  ^(The argument X in
+** sqlite3_file_control(db,SQLITE_FCNTL_VFS_POINTER,X) must be
+** of type "[sqlite3_vfs] **".  This opcodes will set *X
+** to a pointer to the top-level VFS.)^
+** ^When there are multiple VFS shims in the stack, this opcode finds the
+** upper-most shim only.
+**
+** <li>[[SQLITE_FCNTL_PRAGMA]]
+** ^Whenever a [PRAGMA] statement is parsed, an [SQLITE_FCNTL_PRAGMA] 
+** file control is sent to the open [sqlite3_file] object corresponding
+** to the database file to which the pragma statement refers. ^The argument
+** to the [SQLITE_FCNTL_PRAGMA] file control is an array of
+** pointers to strings (char**) in which the second element of the array
+** is the name of the pragma and the third element is the argument to the
+** pragma or NULL if the pragma has no argument.  ^The handler for an
+** [SQLITE_FCNTL_PRAGMA] file control can optionally make the first element
+** of the char** argument point to a string obtained from [sqlite3_mprintf()]
+** or the equivalent and that string will become the result of the pragma or
+** the error message if the pragma fails. ^If the
+** [SQLITE_FCNTL_PRAGMA] file control returns [SQLITE_NOTFOUND], then normal 
+** [PRAGMA] processing continues.  ^If the [SQLITE_FCNTL_PRAGMA]
+** file control returns [SQLITE_OK], then the parser assumes that the
+** VFS has handled the PRAGMA itself and the parser generates a no-op
+** prepared statement if result string is NULL, or that returns a copy
+** of the result string if the string is non-NULL.
+** ^If the [SQLITE_FCNTL_PRAGMA] file control returns
+** any result code other than [SQLITE_OK] or [SQLITE_NOTFOUND], that means
+** that the VFS encountered an error while handling the [PRAGMA] and the
+** compilation of the PRAGMA fails with an error.  ^The [SQLITE_FCNTL_PRAGMA]
+** file control occurs at the beginning of pragma statement analysis and so
+** it is able to override built-in [PRAGMA] statements.
+**
+** <li>[[SQLITE_FCNTL_BUSYHANDLER]]
+** ^The [SQLITE_FCNTL_BUSYHANDLER]
+** file-control may be invoked by SQLite on the database file handle
+** shortly after it is opened in order to provide a custom VFS with access
+** to the connections busy-handler callback. The argument is of type (void **)
+** - an array of two (void *) values. The first (void *) actually points
+** to a function of type (int (*)(void *)). In order to invoke the connections
+** busy-handler, this function should be invoked with the second (void *) in
+** the array as the only argument. If it returns non-zero, then the operation
+** should be retried. If it returns zero, the custom VFS should abandon the
+** current operation.
+**
+** <li>[[SQLITE_FCNTL_TEMPFILENAME]]
+** ^Application can invoke the [SQLITE_FCNTL_TEMPFILENAME] file-control
+** to have SQLite generate a
+** temporary filename using the same algorithm that is followed to generate
+** temporary filenames for TEMP tables and other internal uses.  The
+** argument should be a char** which will be filled with the filename
+** written into memory obtained from [sqlite3_malloc()].  The caller should
+** invoke [sqlite3_free()] on the result to avoid a memory leak.
+**
+** <li>[[SQLITE_FCNTL_MMAP_SIZE]]
+** The [SQLITE_FCNTL_MMAP_SIZE] file control is used to query or set the
+** maximum number of bytes that will be used for memory-mapped I/O.
+** The argument is a pointer to a value of type sqlite3_int64 that
+** is an advisory maximum number of bytes in the file to memory map.  The
+** pointer is overwritten with the old value.  The limit is not changed if
+** the value originally pointed to is negative, and so the current limit 
+** can be queried by passing in a pointer to a negative number.  This
+** file-control is used internally to implement [PRAGMA mmap_size].
+**
+** <li>[[SQLITE_FCNTL_TRACE]]
+** The [SQLITE_FCNTL_TRACE] file control provides advisory information
+** to the VFS about what the higher layers of the SQLite stack are doing.
+** This file control is used by some VFS activity tracing [shims].
+** The argument is a zero-terminated string.  Higher layers in the
+** SQLite stack may generate instances of this file control if
+** the [SQLITE_USE_FCNTL_TRACE] compile-time option is enabled.
+**
+** <li>[[SQLITE_FCNTL_HAS_MOVED]]
+** The [SQLITE_FCNTL_HAS_MOVED] file control interprets its argument as a
+** pointer to an integer and it writes a boolean into that integer depending
+** on whether or not the file has been renamed, moved, or deleted since it
+** was first opened.
+**
+** <li>[[SQLITE_FCNTL_WIN32_GET_HANDLE]]
+** The [SQLITE_FCNTL_WIN32_GET_HANDLE] opcode can be used to obtain the
+** underlying native file handle associated with a file handle.  This file
+** control interprets its argument as a pointer to a native file handle and
+** writes the resulting value there.
+**
+** <li>[[SQLITE_FCNTL_WIN32_SET_HANDLE]]
+** The [SQLITE_FCNTL_WIN32_SET_HANDLE] opcode is used for debugging.  This
+** opcode causes the xFileControl method to swap the file handle with the one
+** pointed to by the pArg argument.  This capability is used during testing
+** and only needs to be supported when SQLITE_TEST is defined.
+**
+** <li>[[SQLITE_FCNTL_WAL_BLOCK]]
+** The [SQLITE_FCNTL_WAL_BLOCK] is a signal to the VFS layer that it might
+** be advantageous to block on the next WAL lock if the lock is not immediately
+** available.  The WAL subsystem issues this signal during rare
+** circumstances in order to fix a problem with priority inversion.
+** Applications should <em>not</em> use this file-control.
+**
+** <li>[[SQLITE_FCNTL_ZIPVFS]]
+** The [SQLITE_FCNTL_ZIPVFS] opcode is implemented by zipvfs only. All other
+** VFS should return SQLITE_NOTFOUND for this opcode.
+**
+** <li>[[SQLITE_FCNTL_RBU]]
+** The [SQLITE_FCNTL_RBU] opcode is implemented by the special VFS used by
+** the RBU extension only.  All other VFS should return SQLITE_NOTFOUND for
+** this opcode.  
+** </ul>
+*/
+#define SQLITE_FCNTL_LOCKSTATE               1
+#define SQLITE_FCNTL_GET_LOCKPROXYFILE       2
+#define SQLITE_FCNTL_SET_LOCKPROXYFILE       3
+#define SQLITE_FCNTL_LAST_ERRNO              4
+#define SQLITE_FCNTL_SIZE_HINT               5
+#define SQLITE_FCNTL_CHUNK_SIZE              6
+#define SQLITE_FCNTL_FILE_POINTER            7
+#define SQLITE_FCNTL_SYNC_OMITTED            8
+#define SQLITE_FCNTL_WIN32_AV_RETRY          9
+#define SQLITE_FCNTL_PERSIST_WAL            10
+#define SQLITE_FCNTL_OVERWRITE              11
+#define SQLITE_FCNTL_VFSNAME                12
+#define SQLITE_FCNTL_POWERSAFE_OVERWRITE    13
+#define SQLITE_FCNTL_PRAGMA                 14
+#define SQLITE_FCNTL_BUSYHANDLER            15
+#define SQLITE_FCNTL_TEMPFILENAME           16
+#define SQLITE_FCNTL_MMAP_SIZE              18
+#define SQLITE_FCNTL_TRACE                  19
+#define SQLITE_FCNTL_HAS_MOVED              20
+#define SQLITE_FCNTL_SYNC                   21
+#define SQLITE_FCNTL_COMMIT_PHASETWO        22
+#define SQLITE_FCNTL_WIN32_SET_HANDLE       23
+#define SQLITE_FCNTL_WAL_BLOCK              24
+#define SQLITE_FCNTL_ZIPVFS                 25
+#define SQLITE_FCNTL_RBU                    26
+#define SQLITE_FCNTL_VFS_POINTER            27
+#define SQLITE_FCNTL_JOURNAL_POINTER        28
+#define SQLITE_FCNTL_WIN32_GET_HANDLE       29
+
+/* deprecated names */
+#define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
+#define SQLITE_SET_LOCKPROXYFILE      SQLITE_FCNTL_SET_LOCKPROXYFILE
+#define SQLITE_LAST_ERRNO             SQLITE_FCNTL_LAST_ERRNO
+
+
+/*
+** CAPI3REF: Mutex Handle
+**
+** The mutex module within SQLite defines [sqlite3_mutex] to be an
+** abstract type for a mutex object.  The SQLite core never looks
+** at the internal representation of an [sqlite3_mutex].  It only
+** deals with pointers to the [sqlite3_mutex] object.
+**
+** Mutexes are created using [sqlite3_mutex_alloc()].
+*/
+typedef struct sqlite3_mutex sqlite3_mutex;
+
+/*
+** CAPI3REF: Loadable Extension Thunk
+**
+** A pointer to the opaque sqlite3_api_routines structure is passed as
+** the third parameter to entry points of [loadable extensions].  This
+** structure must be typedefed in order to work around compiler warnings
+** on some platforms.
+*/
+typedef struct sqlite3_api_routines sqlite3_api_routines;
+
+/*
+** CAPI3REF: OS Interface Object
+**
+** An instance of the sqlite3_vfs object defines the interface between
+** the SQLite core and the underlying operating system.  The "vfs"
+** in the name of the object stands for "virtual file system".  See
+** the [VFS | VFS documentation] for further information.
+**
+** The value of the iVersion field is initially 1 but may be larger in
+** future versions of SQLite.  Additional fields may be appended to this
+** object when the iVersion value is increased.  Note that the structure
+** of the sqlite3_vfs object changes in the transaction between
+** SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not
+** modified.
+**
+** The szOsFile field is the size of the subclassed [sqlite3_file]
+** structure used by this VFS.  mxPathname is the maximum length of
+** a pathname in this VFS.
+**
+** Registered sqlite3_vfs objects are kept on a linked list formed by
+** the pNext pointer.  The [sqlite3_vfs_register()]
+** and [sqlite3_vfs_unregister()] interfaces manage this list
+** in a thread-safe way.  The [sqlite3_vfs_find()] interface
+** searches the list.  Neither the application code nor the VFS
+** implementation should use the pNext pointer.
+**
+** The pNext field is the only field in the sqlite3_vfs
+** structure that SQLite will ever modify.  SQLite will only access
+** or modify this field while holding a particular static mutex.
+** The application should never modify anything within the sqlite3_vfs
+** object once the object has been registered.
+**
+** The zName field holds the name of the VFS module.  The name must
+** be unique across all VFS modules.
+**
+** [[sqlite3_vfs.xOpen]]
+** ^SQLite guarantees that the zFilename parameter to xOpen
+** is either a NULL pointer or string obtained
+** from xFullPathname() with an optional suffix added.
+** ^If a suffix is added to the zFilename parameter, it will
+** consist of a single "-" character followed by no more than
+** 11 alphanumeric and/or "-" characters.
+** ^SQLite further guarantees that
+** the string will be valid and unchanged until xClose() is
+** called. Because of the previous sentence,
+** the [sqlite3_file] can safely store a pointer to the
+** filename if it needs to remember the filename for some reason.
+** If the zFilename parameter to xOpen is a NULL pointer then xOpen
+** must invent its own temporary name for the file.  ^Whenever the 
+** xFilename parameter is NULL it will also be the case that the
+** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].
+**
+** The flags argument to xOpen() includes all bits set in
+** the flags argument to [sqlite3_open_v2()].  Or if [sqlite3_open()]
+** or [sqlite3_open16()] is used, then flags includes at least
+** [SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]. 
+** If xOpen() opens a file read-only then it sets *pOutFlags to
+** include [SQLITE_OPEN_READONLY].  Other bits in *pOutFlags may be set.
+**
+** ^(SQLite will also add one of the following flags to the xOpen()
+** call, depending on the object being opened:
+**
+** <ul>
+** <li>  [SQLITE_OPEN_MAIN_DB]
+** <li>  [SQLITE_OPEN_MAIN_JOURNAL]
+** <li>  [SQLITE_OPEN_TEMP_DB]
+** <li>  [SQLITE_OPEN_TEMP_JOURNAL]
+** <li>  [SQLITE_OPEN_TRANSIENT_DB]
+** <li>  [SQLITE_OPEN_SUBJOURNAL]
+** <li>  [SQLITE_OPEN_MASTER_JOURNAL]
+** <li>  [SQLITE_OPEN_WAL]
+** </ul>)^
+**
+** The file I/O implementation can use the object type flags to
+** change the way it deals with files.  For example, an application
+** that does not care about crash recovery or rollback might make
+** the open of a journal file a no-op.  Writes to this journal would
+** also be no-ops, and any attempt to read the journal would return
+** SQLITE_IOERR.  Or the implementation might recognize that a database
+** file will be doing page-aligned sector reads and writes in a random
+** order and set up its I/O subsystem accordingly.
+**
+** SQLite might also add one of the following flags to the xOpen method:
+**
+** <ul>
+** <li> [SQLITE_OPEN_DELETEONCLOSE]
+** <li> [SQLITE_OPEN_EXCLUSIVE]
+** </ul>
+**
+** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
+** deleted when it is closed.  ^The [SQLITE_OPEN_DELETEONCLOSE]
+** will be set for TEMP databases and their journals, transient
+** databases, and subjournals.
+**
+** ^The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction
+** with the [SQLITE_OPEN_CREATE] flag, which are both directly
+** analogous to the O_EXCL and O_CREAT flags of the POSIX open()
+** API.  The SQLITE_OPEN_EXCLUSIVE flag, when paired with the 
+** SQLITE_OPEN_CREATE, is used to indicate that file should always
+** be created, and that it is an error if it already exists.
+** It is <i>not</i> used to indicate the file should be opened 
+** for exclusive access.
+**
+** ^At least szOsFile bytes of memory are allocated by SQLite
+** to hold the  [sqlite3_file] structure passed as the third
+** argument to xOpen.  The xOpen method does not have to
+** allocate the structure; it should just fill it in.  Note that
+** the xOpen method must set the sqlite3_file.pMethods to either
+** a valid [sqlite3_io_methods] object or to NULL.  xOpen must do
+** this even if the open fails.  SQLite expects that the sqlite3_file.pMethods
+** element will be valid after xOpen returns regardless of the success
+** or failure of the xOpen call.
+**
+** [[sqlite3_vfs.xAccess]]
+** ^The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]
+** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to
+** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]
+** to test whether a file is at least readable.   The file can be a
+** directory.
+**
+** ^SQLite will always allocate at least mxPathname+1 bytes for the
+** output buffer xFullPathname.  The exact size of the output buffer
+** is also passed as a parameter to both  methods. If the output buffer
+** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is
+** handled as a fatal error by SQLite, vfs implementations should endeavor
+** to prevent this by setting mxPathname to a sufficiently large value.
+**
+** The xRandomness(), xSleep(), xCurrentTime(), and xCurrentTimeInt64()
+** interfaces are not strictly a part of the filesystem, but they are
+** included in the VFS structure for completeness.
+** The xRandomness() function attempts to return nBytes bytes
+** of good-quality randomness into zOut.  The return value is
+** the actual number of bytes of randomness obtained.
+** The xSleep() method causes the calling thread to sleep for at
+** least the number of microseconds given.  ^The xCurrentTime()
+** method returns a Julian Day Number for the current date and time as
+** a floating point value.
+** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
+** Day Number multiplied by 86400000 (the number of milliseconds in 
+** a 24-hour day).  
+** ^SQLite will use the xCurrentTimeInt64() method to get the current
+** date and time if that method is available (if iVersion is 2 or 
+** greater and the function pointer is not NULL) and will fall back
+** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
+**
+** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
+** are not used by the SQLite core.  These optional interfaces are provided
+** by some VFSes to facilitate testing of the VFS code. By overriding 
+** system calls with functions under its control, a test program can
+** simulate faults and error conditions that would otherwise be difficult
+** or impossible to induce.  The set of system calls that can be overridden
+** varies from one VFS to another, and from one version of the same VFS to the
+** next.  Applications that use these interfaces must be prepared for any
+** or all of these interfaces to be NULL or for their behavior to change
+** from one release to the next.  Applications must not attempt to access
+** any of these methods if the iVersion of the VFS is less than 3.
+*/
+typedef struct sqlite3_vfs sqlite3_vfs;
+typedef void (*sqlite3_syscall_ptr)(void);
+struct sqlite3_vfs {
+  int iVersion;            /* Structure version number (currently 3) */
+  int szOsFile;            /* Size of subclassed sqlite3_file */
+  int mxPathname;          /* Maximum file pathname length */
+  sqlite3_vfs *pNext;      /* Next registered VFS */
+  const char *zName;       /* Name of this virtual file system */
+  void *pAppData;          /* Pointer to application-specific data */
+  int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
+               int flags, int *pOutFlags);
+  int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
+  int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut);
+  int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
+  void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
+  void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
+  void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void);
+  void (*xDlClose)(sqlite3_vfs*, void*);
+  int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
+  int (*xSleep)(sqlite3_vfs*, int microseconds);
+  int (*xCurrentTime)(sqlite3_vfs*, double*);
+  int (*xGetLastError)(sqlite3_vfs*, int, char *);
+  /*
+  ** The methods above are in version 1 of the sqlite_vfs object
+  ** definition.  Those that follow are added in version 2 or later
+  */
+  int (*xCurrentTimeInt64)(sqlite3_vfs*, sqlite3_int64*);
+  /*
+  ** The methods above are in versions 1 and 2 of the sqlite_vfs object.
+  ** Those below are for version 3 and greater.
+  */
+  int (*xSetSystemCall)(sqlite3_vfs*, const char *zName, sqlite3_syscall_ptr);
+  sqlite3_syscall_ptr (*xGetSystemCall)(sqlite3_vfs*, const char *zName);
+  const char *(*xNextSystemCall)(sqlite3_vfs*, const char *zName);
+  /*
+  ** The methods above are in versions 1 through 3 of the sqlite_vfs object.
+  ** New fields may be appended in future versions.  The iVersion
+  ** value will increment whenever this happens. 
+  */
+};
+
+/*
+** CAPI3REF: Flags for the xAccess VFS method
+**
+** These integer constants can be used as the third parameter to
+** the xAccess method of an [sqlite3_vfs] object.  They determine
+** what kind of permissions the xAccess method is looking for.
+** With SQLITE_ACCESS_EXISTS, the xAccess method
+** simply checks whether the file exists.
+** With SQLITE_ACCESS_READWRITE, the xAccess method
+** checks whether the named directory is both readable and writable
+** (in other words, if files can be added, removed, and renamed within
+** the directory).
+** The SQLITE_ACCESS_READWRITE constant is currently used only by the
+** [temp_store_directory pragma], though this could change in a future
+** release of SQLite.
+** With SQLITE_ACCESS_READ, the xAccess method
+** checks whether the file is readable.  The SQLITE_ACCESS_READ constant is
+** currently unused, though it might be used in a future release of
+** SQLite.
+*/
+#define SQLITE_ACCESS_EXISTS    0
+#define SQLITE_ACCESS_READWRITE 1   /* Used by PRAGMA temp_store_directory */
+#define SQLITE_ACCESS_READ      2   /* Unused */
+
+/*
+** CAPI3REF: Flags for the xShmLock VFS method
+**
+** These integer constants define the various locking operations
+** allowed by the xShmLock method of [sqlite3_io_methods].  The
+** following are the only legal combinations of flags to the
+** xShmLock method:
+**
+** <ul>
+** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_SHARED
+** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE
+** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED
+** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE
+** </ul>
+**
+** When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as
+** was given on the corresponding lock.  
+**
+** The xShmLock method can transition between unlocked and SHARED or
+** between unlocked and EXCLUSIVE.  It cannot transition between SHARED
+** and EXCLUSIVE.
+*/
+#define SQLITE_SHM_UNLOCK       1
+#define SQLITE_SHM_LOCK         2
+#define SQLITE_SHM_SHARED       4
+#define SQLITE_SHM_EXCLUSIVE    8
+
+/*
+** CAPI3REF: Maximum xShmLock index
+**
+** The xShmLock method on [sqlite3_io_methods] may use values
+** between 0 and this upper bound as its "offset" argument.
+** The SQLite core will never attempt to acquire or release a
+** lock outside of this range
+*/
+#define SQLITE_SHM_NLOCK        8
+
+
+/*
+** CAPI3REF: Initialize The SQLite Library
+**
+** ^The sqlite3_initialize() routine initializes the
+** SQLite library.  ^The sqlite3_shutdown() routine
+** deallocates any resources that were allocated by sqlite3_initialize().
+** These routines are designed to aid in process initialization and
+** shutdown on embedded systems.  Workstation applications using
+** SQLite normally do not need to invoke either of these routines.
+**
+** A call to sqlite3_initialize() is an "effective" call if it is
+** the first time sqlite3_initialize() is invoked during the lifetime of
+** the process, or if it is the first time sqlite3_initialize() is invoked
+** following a call to sqlite3_shutdown().  ^(Only an effective call
+** of sqlite3_initialize() does any initialization.  All other calls
+** are harmless no-ops.)^
+**
+** A call to sqlite3_shutdown() is an "effective" call if it is the first
+** call to sqlite3_shutdown() since the last sqlite3_initialize().  ^(Only
+** an effective call to sqlite3_shutdown() does any deinitialization.
+** All other valid calls to sqlite3_shutdown() are harmless no-ops.)^
+**
+** The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown()
+** is not.  The sqlite3_shutdown() interface must only be called from a
+** single thread.  All open [database connections] must be closed and all
+** other SQLite resources must be deallocated prior to invoking
+** sqlite3_shutdown().
+**
+** Among other things, ^sqlite3_initialize() will invoke
+** sqlite3_os_init().  Similarly, ^sqlite3_shutdown()
+** will invoke sqlite3_os_end().
+**
+** ^The sqlite3_initialize() routine returns [SQLITE_OK] on success.
+** ^If for some reason, sqlite3_initialize() is unable to initialize
+** the library (perhaps it is unable to allocate a needed resource such
+** as a mutex) it returns an [error code] other than [SQLITE_OK].
+**
+** ^The sqlite3_initialize() routine is called internally by many other
+** SQLite interfaces so that an application usually does not need to
+** invoke sqlite3_initialize() directly.  For example, [sqlite3_open()]
+** calls sqlite3_initialize() so the SQLite library will be automatically
+** initialized when [sqlite3_open()] is called if it has not be initialized
+** already.  ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]
+** compile-time option, then the automatic calls to sqlite3_initialize()
+** are omitted and the application must call sqlite3_initialize() directly
+** prior to using any other SQLite interface.  For maximum portability,
+** it is recommended that applications always invoke sqlite3_initialize()
+** directly prior to using any other SQLite interface.  Future releases
+** of SQLite may require this.  In other words, the behavior exhibited
+** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the
+** default behavior in some future release of SQLite.
+**
+** The sqlite3_os_init() routine does operating-system specific
+** initialization of the SQLite library.  The sqlite3_os_end()
+** routine undoes the effect of sqlite3_os_init().  Typical tasks
+** performed by these routines include allocation or deallocation
+** of static resources, initialization of global variables,
+** setting up a default [sqlite3_vfs] module, or setting up
+** a default configuration using [sqlite3_config()].
+**
+** The application should never invoke either sqlite3_os_init()
+** or sqlite3_os_end() directly.  The application should only invoke
+** sqlite3_initialize() and sqlite3_shutdown().  The sqlite3_os_init()
+** interface is called automatically by sqlite3_initialize() and
+** sqlite3_os_end() is called by sqlite3_shutdown().  Appropriate
+** implementations for sqlite3_os_init() and sqlite3_os_end()
+** are built into SQLite when it is compiled for Unix, Windows, or OS/2.
+** When [custom builds | built for other platforms]
+** (using the [SQLITE_OS_OTHER=1] compile-time
+** option) the application must supply a suitable implementation for
+** sqlite3_os_init() and sqlite3_os_end().  An application-supplied
+** implementation of sqlite3_os_init() or sqlite3_os_end()
+** must return [SQLITE_OK] on success and some other [error code] upon
+** failure.
+*/
+SQLITE_API int sqlite3_initialize(void);
+SQLITE_API int sqlite3_shutdown(void);
+SQLITE_API int sqlite3_os_init(void);
+SQLITE_API int sqlite3_os_end(void);
+
+/*
+** CAPI3REF: Configuring The SQLite Library
+**
+** The sqlite3_config() interface is used to make global configuration
+** changes to SQLite in order to tune SQLite to the specific needs of
+** the application.  The default configuration is recommended for most
+** applications and so this routine is usually not necessary.  It is
+** provided to support rare applications with unusual needs.
+**
+** <b>The sqlite3_config() interface is not threadsafe. The application
+** must ensure that no other SQLite interfaces are invoked by other
+** threads while sqlite3_config() is running.</b>
+**
+** The sqlite3_config() interface
+** may only be invoked prior to library initialization using
+** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
+** ^If sqlite3_config() is called after [sqlite3_initialize()] and before
+** [sqlite3_shutdown()] then it will return SQLITE_MISUSE.
+** Note, however, that ^sqlite3_config() can be called as part of the
+** implementation of an application-defined [sqlite3_os_init()].
+**
+** The first argument to sqlite3_config() is an integer
+** [configuration option] that determines
+** what property of SQLite is to be configured.  Subsequent arguments
+** vary depending on the [configuration option]
+** in the first argument.
+**
+** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
+** ^If the option is unknown or SQLite is unable to set the option
+** then this routine returns a non-zero [error code].
+*/
+SQLITE_API int sqlite3_config(int, ...);
+
+/*
+** CAPI3REF: Configure database connections
+** METHOD: sqlite3
+**
+** The sqlite3_db_config() interface is used to make configuration
+** changes to a [database connection].  The interface is similar to
+** [sqlite3_config()] except that the changes apply to a single
+** [database connection] (specified in the first argument).
+**
+** The second argument to sqlite3_db_config(D,V,...)  is the
+** [SQLITE_DBCONFIG_LOOKASIDE | configuration verb] - an integer code 
+** that indicates what aspect of the [database connection] is being configured.
+** Subsequent arguments vary depending on the configuration verb.
+**
+** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
+** the call is considered successful.
+*/
+SQLITE_API int sqlite3_db_config(sqlite3*, int op, ...);
+
+/*
+** CAPI3REF: Memory Allocation Routines
+**
+** An instance of this object defines the interface between SQLite
+** and low-level memory allocation routines.
+**
+** This object is used in only one place in the SQLite interface.
+** A pointer to an instance of this object is the argument to
+** [sqlite3_config()] when the configuration option is
+** [SQLITE_CONFIG_MALLOC] or [SQLITE_CONFIG_GETMALLOC].  
+** By creating an instance of this object
+** and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC])
+** during configuration, an application can specify an alternative
+** memory allocation subsystem for SQLite to use for all of its
+** dynamic memory needs.
+**
+** Note that SQLite comes with several [built-in memory allocators]
+** that are perfectly adequate for the overwhelming majority of applications
+** and that this object is only useful to a tiny minority of applications
+** with specialized memory allocation requirements.  This object is
+** also used during testing of SQLite in order to specify an alternative
+** memory allocator that simulates memory out-of-memory conditions in
+** order to verify that SQLite recovers gracefully from such
+** conditions.
+**
+** The xMalloc, xRealloc, and xFree methods must work like the
+** malloc(), realloc() and free() functions from the standard C library.
+** ^SQLite guarantees that the second argument to
+** xRealloc is always a value returned by a prior call to xRoundup.
+**
+** xSize should return the allocated size of a memory allocation
+** previously obtained from xMalloc or xRealloc.  The allocated size
+** is always at least as big as the requested size but may be larger.
+**
+** The xRoundup method returns what would be the allocated size of
+** a memory allocation given a particular requested size.  Most memory
+** allocators round up memory allocations at least to the next multiple
+** of 8.  Some allocators round up to a larger multiple or to a power of 2.
+** Every memory allocation request coming in through [sqlite3_malloc()]
+** or [sqlite3_realloc()] first calls xRoundup.  If xRoundup returns 0, 
+** that causes the corresponding memory allocation to fail.
+**
+** The xInit method initializes the memory allocator.  For example,
+** it might allocate any require mutexes or initialize internal data
+** structures.  The xShutdown method is invoked (indirectly) by
+** [sqlite3_shutdown()] and should deallocate any resources acquired
+** by xInit.  The pAppData pointer is used as the only parameter to
+** xInit and xShutdown.
+**
+** SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes
+** the xInit method, so the xInit method need not be threadsafe.  The
+** xShutdown method is only called from [sqlite3_shutdown()] so it does
+** not need to be threadsafe either.  For all other methods, SQLite
+** holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the
+** [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which
+** it is by default) and so the methods are automatically serialized.
+** However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other
+** methods must be threadsafe or else make their own arrangements for
+** serialization.
+**
+** SQLite will never invoke xInit() more than once without an intervening
+** call to xShutdown().
+*/
+typedef struct sqlite3_mem_methods sqlite3_mem_methods;
+struct sqlite3_mem_methods {
+  void *(*xMalloc)(int);         /* Memory allocation function */
+  void (*xFree)(void*);          /* Free a prior allocation */
+  void *(*xRealloc)(void*,int);  /* Resize an allocation */
+  int (*xSize)(void*);           /* Return the size of an allocation */
+  int (*xRoundup)(int);          /* Round up request size to allocation size */
+  int (*xInit)(void*);           /* Initialize the memory allocator */
+  void (*xShutdown)(void*);      /* Deinitialize the memory allocator */
+  void *pAppData;                /* Argument to xInit() and xShutdown() */
+};
+
+/*
+** CAPI3REF: Configuration Options
+** KEYWORDS: {configuration option}
+**
+** These constants are the available integer configuration options that
+** can be passed as the first argument to the [sqlite3_config()] interface.
+**
+** New configuration options may be added in future releases of SQLite.
+** Existing configuration options might be discontinued.  Applications
+** should check the return code from [sqlite3_config()] to make sure that
+** the call worked.  The [sqlite3_config()] interface will return a
+** non-zero [error code] if a discontinued or unsupported configuration option
+** is invoked.
+**
+** <dl>
+** [[SQLITE_CONFIG_SINGLETHREAD]] <dt>SQLITE_CONFIG_SINGLETHREAD</dt>
+** <dd>There are no arguments to this option.  ^This option sets the
+** [threading mode] to Single-thread.  In other words, it disables
+** all mutexing and puts SQLite into a mode where it can only be used
+** by a single thread.   ^If SQLite is compiled with
+** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
+** it is not possible to change the [threading mode] from its default
+** value of Single-thread and so [sqlite3_config()] will return 
+** [SQLITE_ERROR] if called with the SQLITE_CONFIG_SINGLETHREAD
+** configuration option.</dd>
+**
+** [[SQLITE_CONFIG_MULTITHREAD]] <dt>SQLITE_CONFIG_MULTITHREAD</dt>
+** <dd>There are no arguments to this option.  ^This option sets the
+** [threading mode] to Multi-thread.  In other words, it disables
+** mutexing on [database connection] and [prepared statement] objects.
+** The application is responsible for serializing access to
+** [database connections] and [prepared statements].  But other mutexes
+** are enabled so that SQLite will be safe to use in a multi-threaded
+** environment as long as no two threads attempt to use the same
+** [database connection] at the same time.  ^If SQLite is compiled with
+** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
+** it is not possible to set the Multi-thread [threading mode] and
+** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
+** SQLITE_CONFIG_MULTITHREAD configuration option.</dd>
+**
+** [[SQLITE_CONFIG_SERIALIZED]] <dt>SQLITE_CONFIG_SERIALIZED</dt>
+** <dd>There are no arguments to this option.  ^This option sets the
+** [threading mode] to Serialized. In other words, this option enables
+** all mutexes including the recursive
+** mutexes on [database connection] and [prepared statement] objects.
+** In this mode (which is the default when SQLite is compiled with
+** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access
+** to [database connections] and [prepared statements] so that the
+** application is free to use the same [database connection] or the
+** same [prepared statement] in different threads at the same time.
+** ^If SQLite is compiled with
+** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
+** it is not possible to set the Serialized [threading mode] and
+** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
+** SQLITE_CONFIG_SERIALIZED configuration option.</dd>
+**
+** [[SQLITE_CONFIG_MALLOC]] <dt>SQLITE_CONFIG_MALLOC</dt>
+** <dd> ^(The SQLITE_CONFIG_MALLOC option takes a single argument which is 
+** a pointer to an instance of the [sqlite3_mem_methods] structure.
+** The argument specifies
+** alternative low-level memory allocation routines to be used in place of
+** the memory allocation routines built into SQLite.)^ ^SQLite makes
+** its own private copy of the content of the [sqlite3_mem_methods] structure
+** before the [sqlite3_config()] call returns.</dd>
+**
+** [[SQLITE_CONFIG_GETMALLOC]] <dt>SQLITE_CONFIG_GETMALLOC</dt>
+** <dd> ^(The SQLITE_CONFIG_GETMALLOC option takes a single argument which
+** is a pointer to an instance of the [sqlite3_mem_methods] structure.
+** The [sqlite3_mem_methods]
+** structure is filled with the currently defined memory allocation routines.)^
+** This option can be used to overload the default memory allocation
+** routines with a wrapper that simulations memory allocation failure or
+** tracks memory usage, for example. </dd>
+**
+** [[SQLITE_CONFIG_MEMSTATUS]] <dt>SQLITE_CONFIG_MEMSTATUS</dt>
+** <dd> ^The SQLITE_CONFIG_MEMSTATUS option takes single argument of type int,
+** interpreted as a boolean, which enables or disables the collection of
+** memory allocation statistics. ^(When memory allocation statistics are
+** disabled, the following SQLite interfaces become non-operational:
+**   <ul>
+**   <li> [sqlite3_memory_used()]
+**   <li> [sqlite3_memory_highwater()]
+**   <li> [sqlite3_soft_heap_limit64()]
+**   <li> [sqlite3_status64()]
+**   </ul>)^
+** ^Memory allocation statistics are enabled by default unless SQLite is
+** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
+** allocation statistics are disabled by default.
+** </dd>
+**
+** [[SQLITE_CONFIG_SCRATCH]] <dt>SQLITE_CONFIG_SCRATCH</dt>
+** <dd> ^The SQLITE_CONFIG_SCRATCH option specifies a static memory buffer
+** that SQLite can use for scratch memory.  ^(There are three arguments
+** to SQLITE_CONFIG_SCRATCH:  A pointer an 8-byte
+** aligned memory buffer from which the scratch allocations will be
+** drawn, the size of each scratch allocation (sz),
+** and the maximum number of scratch allocations (N).)^
+** The first argument must be a pointer to an 8-byte aligned buffer
+** of at least sz*N bytes of memory.
+** ^SQLite will not use more than one scratch buffers per thread.
+** ^SQLite will never request a scratch buffer that is more than 6
+** times the database page size.
+** ^If SQLite needs needs additional
+** scratch memory beyond what is provided by this configuration option, then 
+** [sqlite3_malloc()] will be used to obtain the memory needed.<p>
+** ^When the application provides any amount of scratch memory using
+** SQLITE_CONFIG_SCRATCH, SQLite avoids unnecessary large
+** [sqlite3_malloc|heap allocations].
+** This can help [Robson proof|prevent memory allocation failures] due to heap
+** fragmentation in low-memory embedded systems.
+** </dd>
+**
+** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>
+** <dd> ^The SQLITE_CONFIG_PAGECACHE option specifies a memory pool
+** that SQLite can use for the database page cache with the default page
+** cache implementation.  
+** This configuration option is a no-op if an application-define page
+** cache implementation is loaded using the [SQLITE_CONFIG_PCACHE2].
+** ^There are three arguments to SQLITE_CONFIG_PAGECACHE: A pointer to
+** 8-byte aligned memory (pMem), the size of each page cache line (sz),
+** and the number of cache lines (N).
+** The sz argument should be the size of the largest database page
+** (a power of two between 512 and 65536) plus some extra bytes for each
+** page header.  ^The number of extra bytes needed by the page header
+** can be determined using [SQLITE_CONFIG_PCACHE_HDRSZ].
+** ^It is harmless, apart from the wasted memory,
+** for the sz parameter to be larger than necessary.  The pMem
+** argument must be either a NULL pointer or a pointer to an 8-byte
+** aligned block of memory of at least sz*N bytes, otherwise
+** subsequent behavior is undefined.
+** ^When pMem is not NULL, SQLite will strive to use the memory provided
+** to satisfy page cache needs, falling back to [sqlite3_malloc()] if
+** a page cache line is larger than sz bytes or if all of the pMem buffer
+** is exhausted.
+** ^If pMem is NULL and N is non-zero, then each database connection
+** does an initial bulk allocation for page cache memory
+** from [sqlite3_malloc()] sufficient for N cache lines if N is positive or
+** of -1024*N bytes if N is negative, . ^If additional
+** page cache memory is needed beyond what is provided by the initial
+** allocation, then SQLite goes to [sqlite3_malloc()] separately for each
+** additional cache line. </dd>
+**
+** [[SQLITE_CONFIG_HEAP]] <dt>SQLITE_CONFIG_HEAP</dt>
+** <dd> ^The SQLITE_CONFIG_HEAP option specifies a static memory buffer 
+** that SQLite will use for all of its dynamic memory allocation needs
+** beyond those provided for by [SQLITE_CONFIG_SCRATCH] and
+** [SQLITE_CONFIG_PAGECACHE].
+** ^The SQLITE_CONFIG_HEAP option is only available if SQLite is compiled
+** with either [SQLITE_ENABLE_MEMSYS3] or [SQLITE_ENABLE_MEMSYS5] and returns
+** [SQLITE_ERROR] if invoked otherwise.
+** ^There are three arguments to SQLITE_CONFIG_HEAP:
+** An 8-byte aligned pointer to the memory,
+** the number of bytes in the memory buffer, and the minimum allocation size.
+** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
+** to using its default memory allocator (the system malloc() implementation),
+** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
+** memory pointer is not NULL then the alternative memory
+** allocator is engaged to handle all of SQLites memory allocation needs.
+** The first pointer (the memory pointer) must be aligned to an 8-byte
+** boundary or subsequent behavior of SQLite will be undefined.
+** The minimum allocation size is capped at 2**12. Reasonable values
+** for the minimum allocation size are 2**5 through 2**8.</dd>
+**
+** [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt>
+** <dd> ^(The SQLITE_CONFIG_MUTEX option takes a single argument which is a
+** pointer to an instance of the [sqlite3_mutex_methods] structure.
+** The argument specifies alternative low-level mutex routines to be used
+** in place the mutex routines built into SQLite.)^  ^SQLite makes a copy of
+** the content of the [sqlite3_mutex_methods] structure before the call to
+** [sqlite3_config()] returns. ^If SQLite is compiled with
+** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
+** the entire mutexing subsystem is omitted from the build and hence calls to
+** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will
+** return [SQLITE_ERROR].</dd>
+**
+** [[SQLITE_CONFIG_GETMUTEX]] <dt>SQLITE_CONFIG_GETMUTEX</dt>
+** <dd> ^(The SQLITE_CONFIG_GETMUTEX option takes a single argument which
+** is a pointer to an instance of the [sqlite3_mutex_methods] structure.  The
+** [sqlite3_mutex_methods]
+** structure is filled with the currently defined mutex routines.)^
+** This option can be used to overload the default mutex allocation
+** routines with a wrapper used to track mutex usage for performance
+** profiling or testing, for example.   ^If SQLite is compiled with
+** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
+** the entire mutexing subsystem is omitted from the build and hence calls to
+** [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will
+** return [SQLITE_ERROR].</dd>
+**
+** [[SQLITE_CONFIG_LOOKASIDE]] <dt>SQLITE_CONFIG_LOOKASIDE</dt>
+** <dd> ^(The SQLITE_CONFIG_LOOKASIDE option takes two arguments that determine
+** the default size of lookaside memory on each [database connection].
+** The first argument is the
+** size of each lookaside buffer slot and the second is the number of
+** slots allocated to each database connection.)^  ^(SQLITE_CONFIG_LOOKASIDE
+** sets the <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE]
+** option to [sqlite3_db_config()] can be used to change the lookaside
+** configuration on individual connections.)^ </dd>
+**
+** [[SQLITE_CONFIG_PCACHE2]] <dt>SQLITE_CONFIG_PCACHE2</dt>
+** <dd> ^(The SQLITE_CONFIG_PCACHE2 option takes a single argument which is 
+** a pointer to an [sqlite3_pcache_methods2] object.  This object specifies
+** the interface to a custom page cache implementation.)^
+** ^SQLite makes a copy of the [sqlite3_pcache_methods2] object.</dd>
+**
+** [[SQLITE_CONFIG_GETPCACHE2]] <dt>SQLITE_CONFIG_GETPCACHE2</dt>
+** <dd> ^(The SQLITE_CONFIG_GETPCACHE2 option takes a single argument which
+** is a pointer to an [sqlite3_pcache_methods2] object.  SQLite copies of
+** the current page cache implementation into that object.)^ </dd>
+**
+** [[SQLITE_CONFIG_LOG]] <dt>SQLITE_CONFIG_LOG</dt>
+** <dd> The SQLITE_CONFIG_LOG option is used to configure the SQLite
+** global [error log].
+** (^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
+** function with a call signature of void(*)(void*,int,const char*), 
+** and a pointer to void. ^If the function pointer is not NULL, it is
+** invoked by [sqlite3_log()] to process each logging event.  ^If the
+** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.
+** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is
+** passed through as the first parameter to the application-defined logger
+** function whenever that function is invoked.  ^The second parameter to
+** the logger function is a copy of the first parameter to the corresponding
+** [sqlite3_log()] call and is intended to be a [result code] or an
+** [extended result code].  ^The third parameter passed to the logger is
+** log message after formatting via [sqlite3_snprintf()].
+** The SQLite logging interface is not reentrant; the logger function
+** supplied by the application must not invoke any SQLite interface.
+** In a multi-threaded application, the application-defined logger
+** function must be threadsafe. </dd>
+**
+** [[SQLITE_CONFIG_URI]] <dt>SQLITE_CONFIG_URI
+** <dd>^(The SQLITE_CONFIG_URI option takes a single argument of type int.
+** If non-zero, then URI handling is globally enabled. If the parameter is zero,
+** then URI handling is globally disabled.)^ ^If URI handling is globally
+** enabled, all filenames passed to [sqlite3_open()], [sqlite3_open_v2()],
+** [sqlite3_open16()] or
+** specified as part of [ATTACH] commands are interpreted as URIs, regardless
+** of whether or not the [SQLITE_OPEN_URI] flag is set when the database
+** connection is opened. ^If it is globally disabled, filenames are
+** only interpreted as URIs if the SQLITE_OPEN_URI flag is set when the
+** database connection is opened. ^(By default, URI handling is globally
+** disabled. The default value may be changed by compiling with the
+** [SQLITE_USE_URI] symbol defined.)^
+**
+** [[SQLITE_CONFIG_COVERING_INDEX_SCAN]] <dt>SQLITE_CONFIG_COVERING_INDEX_SCAN
+** <dd>^The SQLITE_CONFIG_COVERING_INDEX_SCAN option takes a single integer
+** argument which is interpreted as a boolean in order to enable or disable
+** the use of covering indices for full table scans in the query optimizer.
+** ^The default setting is determined
+** by the [SQLITE_ALLOW_COVERING_INDEX_SCAN] compile-time option, or is "on"
+** if that compile-time option is omitted.
+** The ability to disable the use of covering indices for full table scans
+** is because some incorrectly coded legacy applications might malfunction
+** when the optimization is enabled.  Providing the ability to
+** disable the optimization allows the older, buggy application code to work
+** without change even with newer versions of SQLite.
+**
+** [[SQLITE_CONFIG_PCACHE]] [[SQLITE_CONFIG_GETPCACHE]]
+** <dt>SQLITE_CONFIG_PCACHE and SQLITE_CONFIG_GETPCACHE
+** <dd> These options are obsolete and should not be used by new code.
+** They are retained for backwards compatibility but are now no-ops.
+** </dd>
+**
+** [[SQLITE_CONFIG_SQLLOG]]
+** <dt>SQLITE_CONFIG_SQLLOG
+** <dd>This option is only available if sqlite is compiled with the
+** [SQLITE_ENABLE_SQLLOG] pre-processor macro defined. The first argument should
+** be a pointer to a function of type void(*)(void*,sqlite3*,const char*, int).
+** The second should be of type (void*). The callback is invoked by the library
+** in three separate circumstances, identified by the value passed as the
+** fourth parameter. If the fourth parameter is 0, then the database connection
+** passed as the second argument has just been opened. The third argument
+** points to a buffer containing the name of the main database file. If the
+** fourth parameter is 1, then the SQL statement that the third parameter
+** points to has just been executed. Or, if the fourth parameter is 2, then
+** the connection being passed as the second parameter is being closed. The
+** third parameter is passed NULL In this case.  An example of using this
+** configuration option can be seen in the "test_sqllog.c" source file in
+** the canonical SQLite source tree.</dd>
+**
+** [[SQLITE_CONFIG_MMAP_SIZE]]
+** <dt>SQLITE_CONFIG_MMAP_SIZE
+** <dd>^SQLITE_CONFIG_MMAP_SIZE takes two 64-bit integer (sqlite3_int64) values
+** that are the default mmap size limit (the default setting for
+** [PRAGMA mmap_size]) and the maximum allowed mmap size limit.
+** ^The default setting can be overridden by each database connection using
+** either the [PRAGMA mmap_size] command, or by using the
+** [SQLITE_FCNTL_MMAP_SIZE] file control.  ^(The maximum allowed mmap size
+** will be silently truncated if necessary so that it does not exceed the
+** compile-time maximum mmap size set by the
+** [SQLITE_MAX_MMAP_SIZE] compile-time option.)^
+** ^If either argument to this option is negative, then that argument is
+** changed to its compile-time default.
+**
+** [[SQLITE_CONFIG_WIN32_HEAPSIZE]]
+** <dt>SQLITE_CONFIG_WIN32_HEAPSIZE
+** <dd>^The SQLITE_CONFIG_WIN32_HEAPSIZE option is only available if SQLite is
+** compiled for Windows with the [SQLITE_WIN32_MALLOC] pre-processor macro
+** defined. ^SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit unsigned integer value
+** that specifies the maximum size of the created heap.
+**
+** [[SQLITE_CONFIG_PCACHE_HDRSZ]]
+** <dt>SQLITE_CONFIG_PCACHE_HDRSZ
+** <dd>^The SQLITE_CONFIG_PCACHE_HDRSZ option takes a single parameter which
+** is a pointer to an integer and writes into that integer the number of extra
+** bytes per page required for each page in [SQLITE_CONFIG_PAGECACHE].
+** The amount of extra space required can change depending on the compiler,
+** target platform, and SQLite version.
+**
+** [[SQLITE_CONFIG_PMASZ]]
+** <dt>SQLITE_CONFIG_PMASZ
+** <dd>^The SQLITE_CONFIG_PMASZ option takes a single parameter which
+** is an unsigned integer and sets the "Minimum PMA Size" for the multithreaded
+** sorter to that integer.  The default minimum PMA Size is set by the
+** [SQLITE_SORTER_PMASZ] compile-time option.  New threads are launched
+** to help with sort operations when multithreaded sorting
+** is enabled (using the [PRAGMA threads] command) and the amount of content
+** to be sorted exceeds the page size times the minimum of the
+** [PRAGMA cache_size] setting and this value.
+**
+** [[SQLITE_CONFIG_STMTJRNL_SPILL]]
+** <dt>SQLITE_CONFIG_STMTJRNL_SPILL
+** <dd>^The SQLITE_CONFIG_STMTJRNL_SPILL option takes a single parameter which
+** becomes the [statement journal] spill-to-disk threshold.  
+** [Statement journals] are held in memory until their size (in bytes)
+** exceeds this threshold, at which point they are written to disk.
+** Or if the threshold is -1, statement journals are always held
+** exclusively in memory.
+** Since many statement journals never become large, setting the spill
+** threshold to a value such as 64KiB can greatly reduce the amount of
+** I/O required to support statement rollback.
+** The default value for this setting is controlled by the
+** [SQLITE_STMTJRNL_SPILL] compile-time option.
+** </dl>
+*/
+#define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
+#define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
+#define SQLITE_CONFIG_SERIALIZED    3  /* nil */
+#define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
+#define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
+#define SQLITE_CONFIG_SCRATCH       6  /* void*, int sz, int N */
+#define SQLITE_CONFIG_PAGECACHE     7  /* void*, int sz, int N */
+#define SQLITE_CONFIG_HEAP          8  /* void*, int nByte, int min */
+#define SQLITE_CONFIG_MEMSTATUS     9  /* boolean */
+#define SQLITE_CONFIG_MUTEX        10  /* sqlite3_mutex_methods* */
+#define SQLITE_CONFIG_GETMUTEX     11  /* sqlite3_mutex_methods* */
+/* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */ 
+#define SQLITE_CONFIG_LOOKASIDE    13  /* int int */
+#define SQLITE_CONFIG_PCACHE       14  /* no-op */
+#define SQLITE_CONFIG_GETPCACHE    15  /* no-op */
+#define SQLITE_CONFIG_LOG          16  /* xFunc, void* */
+#define SQLITE_CONFIG_URI          17  /* int */
+#define SQLITE_CONFIG_PCACHE2      18  /* sqlite3_pcache_methods2* */
+#define SQLITE_CONFIG_GETPCACHE2   19  /* sqlite3_pcache_methods2* */
+#define SQLITE_CONFIG_COVERING_INDEX_SCAN 20  /* int */
+#define SQLITE_CONFIG_SQLLOG       21  /* xSqllog, void* */
+#define SQLITE_CONFIG_MMAP_SIZE    22  /* sqlite3_int64, sqlite3_int64 */
+#define SQLITE_CONFIG_WIN32_HEAPSIZE      23  /* int nByte */
+#define SQLITE_CONFIG_PCACHE_HDRSZ        24  /* int *psz */
+#define SQLITE_CONFIG_PMASZ               25  /* unsigned int szPma */
+#define SQLITE_CONFIG_STMTJRNL_SPILL      26  /* int nByte */
+
+/*
+** CAPI3REF: Database Connection Configuration Options
+**
+** These constants are the available integer configuration options that
+** can be passed as the second argument to the [sqlite3_db_config()] interface.
+**
+** New configuration options may be added in future releases of SQLite.
+** Existing configuration options might be discontinued.  Applications
+** should check the return code from [sqlite3_db_config()] to make sure that
+** the call worked.  ^The [sqlite3_db_config()] interface will return a
+** non-zero [error code] if a discontinued or unsupported configuration option
+** is invoked.
+**
+** <dl>
+** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
+** <dd> ^This option takes three additional arguments that determine the 
+** [lookaside memory allocator] configuration for the [database connection].
+** ^The first argument (the third parameter to [sqlite3_db_config()] is a
+** pointer to a memory buffer to use for lookaside memory.
+** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
+** may be NULL in which case SQLite will allocate the
+** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the
+** size of each lookaside buffer slot.  ^The third argument is the number of
+** slots.  The size of the buffer in the first argument must be greater than
+** or equal to the product of the second and third arguments.  The buffer
+** must be aligned to an 8-byte boundary.  ^If the second argument to
+** SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally
+** rounded down to the next smaller multiple of 8.  ^(The lookaside memory
+** configuration for a database connection can only be changed when that
+** connection is not currently using lookaside memory, or in other words
+** when the "current value" returned by
+** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.
+** Any attempt to change the lookaside memory configuration when lookaside
+** memory is in use leaves the configuration unchanged and returns 
+** [SQLITE_BUSY].)^</dd>
+**
+** <dt>SQLITE_DBCONFIG_ENABLE_FKEY</dt>
+** <dd> ^This option is used to enable or disable the enforcement of
+** [foreign key constraints].  There should be two additional arguments.
+** The first argument is an integer which is 0 to disable FK enforcement,
+** positive to enable FK enforcement or negative to leave FK enforcement
+** unchanged.  The second parameter is a pointer to an integer into which
+** is written 0 or 1 to indicate whether FK enforcement is off or on
+** following this call.  The second parameter may be a NULL pointer, in
+** which case the FK enforcement setting is not reported back. </dd>
+**
+** <dt>SQLITE_DBCONFIG_ENABLE_TRIGGER</dt>
+** <dd> ^This option is used to enable or disable [CREATE TRIGGER | triggers].
+** There should be two additional arguments.
+** The first argument is an integer which is 0 to disable triggers,
+** positive to enable triggers or negative to leave the setting unchanged.
+** The second parameter is a pointer to an integer into which
+** is written 0 or 1 to indicate whether triggers are disabled or enabled
+** following this call.  The second parameter may be a NULL pointer, in
+** which case the trigger setting is not reported back. </dd>
+**
+** <dt>SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER</dt>
+** <dd> ^This option is used to enable or disable the two-argument
+** version of the [fts3_tokenizer()] function which is part of the
+** [FTS3] full-text search engine extension.
+** There should be two additional arguments.
+** The first argument is an integer which is 0 to disable fts3_tokenizer() or
+** positive to enable fts3_tokenizer() or negative to leave the setting
+** unchanged.
+** The second parameter is a pointer to an integer into which
+** is written 0 or 1 to indicate whether fts3_tokenizer is disabled or enabled
+** following this call.  The second parameter may be a NULL pointer, in
+** which case the new setting is not reported back. </dd>
+**
+** <dt>SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION</dt>
+** <dd> ^This option is used to enable or disable the [sqlite3_load_extension()]
+** interface independently of the [load_extension()] SQL function.
+** The [sqlite3_enable_load_extension()] API enables or disables both the
+** C-API [sqlite3_load_extension()] and the SQL function [load_extension()].
+** There should be two additional arguments.
+** When the first argument to this interface is 1, then only the C-API is
+** enabled and the SQL function remains disabled.  If the first argument to
+** this interface is 0, then both the C-API and the SQL function are disabled.
+** If the first argument is -1, then no changes are made to state of either the
+** C-API or the SQL function.
+** The second parameter is a pointer to an integer into which
+** is written 0 or 1 to indicate whether [sqlite3_load_extension()] interface
+** is disabled or enabled following this call.  The second parameter may
+** be a NULL pointer, in which case the new setting is not reported back.
+** </dd>
+**
+** <dt>SQLITE_DBCONFIG_MAINDBNAME</dt>
+** <dd> ^This option is used to change the name of the "main" database
+** schema.  ^The sole argument is a pointer to a constant UTF8 string
+** which will become the new schema name in place of "main".  ^SQLite
+** does not make a copy of the new main schema name string, so the application
+** must ensure that the argument passed into this DBCONFIG option is unchanged
+** until after the database connection closes.
+** </dd>
+**
+** </dl>
+*/
+#define SQLITE_DBCONFIG_MAINDBNAME            1000 /* const char* */
+#define SQLITE_DBCONFIG_LOOKASIDE             1001 /* void* int int */
+#define SQLITE_DBCONFIG_ENABLE_FKEY           1002 /* int int* */
+#define SQLITE_DBCONFIG_ENABLE_TRIGGER        1003 /* int int* */
+#define SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER 1004 /* int int* */
+#define SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION 1005 /* int int* */
+
+
+/*
+** CAPI3REF: Enable Or Disable Extended Result Codes
+** METHOD: sqlite3
+**
+** ^The sqlite3_extended_result_codes() routine enables or disables the
+** [extended result codes] feature of SQLite. ^The extended result
+** codes are disabled by default for historical compatibility.
+*/
+SQLITE_API int sqlite3_extended_result_codes(sqlite3*, int onoff);
+
+/*
+** CAPI3REF: Last Insert Rowid
+** METHOD: sqlite3
+**
+** ^Each entry in most SQLite tables (except for [WITHOUT ROWID] tables)
+** has a unique 64-bit signed
+** integer key called the [ROWID | "rowid"]. ^The rowid is always available
+** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
+** names are not also used by explicitly declared columns. ^If
+** the table has a column of type [INTEGER PRIMARY KEY] then that column
+** is another alias for the rowid.
+**
+** ^The sqlite3_last_insert_rowid(D) interface returns the [rowid] of the 
+** most recent successful [INSERT] into a rowid table or [virtual table]
+** on database connection D.
+** ^Inserts into [WITHOUT ROWID] tables are not recorded.
+** ^If no successful [INSERT]s into rowid tables
+** have ever occurred on the database connection D, 
+** then sqlite3_last_insert_rowid(D) returns zero.
+**
+** ^(If an [INSERT] occurs within a trigger or within a [virtual table]
+** method, then this routine will return the [rowid] of the inserted
+** row as long as the trigger or virtual table method is running.
+** But once the trigger or virtual table method ends, the value returned 
+** by this routine reverts to what it was before the trigger or virtual
+** table method began.)^
+**
+** ^An [INSERT] that fails due to a constraint violation is not a
+** successful [INSERT] and does not change the value returned by this
+** routine.  ^Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,
+** and INSERT OR ABORT make no changes to the return value of this
+** routine when their insertion fails.  ^(When INSERT OR REPLACE
+** encounters a constraint violation, it does not fail.  The
+** INSERT continues to completion after deleting rows that caused
+** the constraint problem so INSERT OR REPLACE will always change
+** the return value of this interface.)^
+**
+** ^For the purposes of this routine, an [INSERT] is considered to
+** be successful even if it is subsequently rolled back.
+**
+** This function is accessible to SQL statements via the
+** [last_insert_rowid() SQL function].
+**
+** If a separate thread performs a new [INSERT] on the same
+** database connection while the [sqlite3_last_insert_rowid()]
+** function is running and thus changes the last insert [rowid],
+** then the value returned by [sqlite3_last_insert_rowid()] is
+** unpredictable and might not equal either the old or the new
+** last insert [rowid].
+*/
+SQLITE_API sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*);
+
+/*
+** CAPI3REF: Count The Number Of Rows Modified
+** METHOD: sqlite3
+**
+** ^This function returns the number of rows modified, inserted or
+** deleted by the most recently completed INSERT, UPDATE or DELETE
+** statement on the database connection specified by the only parameter.
+** ^Executing any other type of SQL statement does not modify the value
+** returned by this function.
+**
+** ^Only changes made directly by the INSERT, UPDATE or DELETE statement are
+** considered - auxiliary changes caused by [CREATE TRIGGER | triggers], 
+** [foreign key actions] or [REPLACE] constraint resolution are not counted.
+** 
+** Changes to a view that are intercepted by 
+** [INSTEAD OF trigger | INSTEAD OF triggers] are not counted. ^The value 
+** returned by sqlite3_changes() immediately after an INSERT, UPDATE or 
+** DELETE statement run on a view is always zero. Only changes made to real 
+** tables are counted.
+**
+** Things are more complicated if the sqlite3_changes() function is
+** executed while a trigger program is running. This may happen if the
+** program uses the [changes() SQL function], or if some other callback
+** function invokes sqlite3_changes() directly. Essentially:
+** 
+** <ul>
+**   <li> ^(Before entering a trigger program the value returned by
+**        sqlite3_changes() function is saved. After the trigger program 
+**        has finished, the original value is restored.)^
+** 
+**   <li> ^(Within a trigger program each INSERT, UPDATE and DELETE 
+**        statement sets the value returned by sqlite3_changes() 
+**        upon completion as normal. Of course, this value will not include 
+**        any changes performed by sub-triggers, as the sqlite3_changes() 
+**        value will be saved and restored after each sub-trigger has run.)^
+** </ul>
+** 
+** ^This means that if the changes() SQL function (or similar) is used
+** by the first INSERT, UPDATE or DELETE statement within a trigger, it 
+** returns the value as set when the calling statement began executing.
+** ^If it is used by the second or subsequent such statement within a trigger 
+** program, the value returned reflects the number of rows modified by the 
+** previous INSERT, UPDATE or DELETE statement within the same trigger.
+**
+** See also the [sqlite3_total_changes()] interface, the
+** [count_changes pragma], and the [changes() SQL function].
+**
+** If a separate thread makes changes on the same database connection
+** while [sqlite3_changes()] is running then the value returned
+** is unpredictable and not meaningful.
+*/
+SQLITE_API int sqlite3_changes(sqlite3*);
+
+/*
+** CAPI3REF: Total Number Of Rows Modified
+** METHOD: sqlite3
+**
+** ^This function returns the total number of rows inserted, modified or
+** deleted by all [INSERT], [UPDATE] or [DELETE] statements completed
+** since the database connection was opened, including those executed as
+** part of trigger programs. ^Executing any other type of SQL statement
+** does not affect the value returned by sqlite3_total_changes().
+** 
+** ^Changes made as part of [foreign key actions] are included in the
+** count, but those made as part of REPLACE constraint resolution are
+** not. ^Changes to a view that are intercepted by INSTEAD OF triggers 
+** are not counted.
+** 
+** See also the [sqlite3_changes()] interface, the
+** [count_changes pragma], and the [total_changes() SQL function].
+**
+** If a separate thread makes changes on the same database connection
+** while [sqlite3_total_changes()] is running then the value
+** returned is unpredictable and not meaningful.
+*/
+SQLITE_API int sqlite3_total_changes(sqlite3*);
+
+/*
+** CAPI3REF: Interrupt A Long-Running Query
+** METHOD: sqlite3
+**
+** ^This function causes any pending database operation to abort and
+** return at its earliest opportunity. This routine is typically
+** called in response to a user action such as pressing "Cancel"
+** or Ctrl-C where the user wants a long query operation to halt
+** immediately.
+**
+** ^It is safe to call this routine from a thread different from the
+** thread that is currently running the database operation.  But it
+** is not safe to call this routine with a [database connection] that
+** is closed or might close before sqlite3_interrupt() returns.
+**
+** ^If an SQL operation is very nearly finished at the time when
+** sqlite3_interrupt() is called, then it might not have an opportunity
+** to be interrupted and might continue to completion.
+**
+** ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT].
+** ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE
+** that is inside an explicit transaction, then the entire transaction
+** will be rolled back automatically.
+**
+** ^The sqlite3_interrupt(D) call is in effect until all currently running
+** SQL statements on [database connection] D complete.  ^Any new SQL statements
+** that are started after the sqlite3_interrupt() call and before the 
+** running statements reaches zero are interrupted as if they had been
+** running prior to the sqlite3_interrupt() call.  ^New SQL statements
+** that are started after the running statement count reaches zero are
+** not effected by the sqlite3_interrupt().
+** ^A call to sqlite3_interrupt(D) that occurs when there are no running
+** SQL statements is a no-op and has no effect on SQL statements
+** that are started after the sqlite3_interrupt() call returns.
+**
+** If the database connection closes while [sqlite3_interrupt()]
+** is running then bad things will likely happen.
+*/
+SQLITE_API void sqlite3_interrupt(sqlite3*);
+
+/*
+** CAPI3REF: Determine If An SQL Statement Is Complete
+**
+** These routines are useful during command-line input to determine if the
+** currently entered text seems to form a complete SQL statement or
+** if additional input is needed before sending the text into
+** SQLite for parsing.  ^These routines return 1 if the input string
+** appears to be a complete SQL statement.  ^A statement is judged to be
+** complete if it ends with a semicolon token and is not a prefix of a
+** well-formed CREATE TRIGGER statement.  ^Semicolons that are embedded within
+** string literals or quoted identifier names or comments are not
+** independent tokens (they are part of the token in which they are
+** embedded) and thus do not count as a statement terminator.  ^Whitespace
+** and comments that follow the final semicolon are ignored.
+**
+** ^These routines return 0 if the statement is incomplete.  ^If a
+** memory allocation fails, then SQLITE_NOMEM is returned.
+**
+** ^These routines do not parse the SQL statements thus
+** will not detect syntactically incorrect SQL.
+**
+** ^(If SQLite has not been initialized using [sqlite3_initialize()] prior 
+** to invoking sqlite3_complete16() then sqlite3_initialize() is invoked
+** automatically by sqlite3_complete16().  If that initialization fails,
+** then the return value from sqlite3_complete16() will be non-zero
+** regardless of whether or not the input SQL is complete.)^
+**
+** The input to [sqlite3_complete()] must be a zero-terminated
+** UTF-8 string.
+**
+** The input to [sqlite3_complete16()] must be a zero-terminated
+** UTF-16 string in native byte order.
+*/
+SQLITE_API int sqlite3_complete(const char *sql);
+SQLITE_API int sqlite3_complete16(const void *sql);
+
+/*
+** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors
+** KEYWORDS: {busy-handler callback} {busy handler}
+** METHOD: sqlite3
+**
+** ^The sqlite3_busy_handler(D,X,P) routine sets a callback function X
+** that might be invoked with argument P whenever
+** an attempt is made to access a database table associated with
+** [database connection] D when another thread
+** or process has the table locked.
+** The sqlite3_busy_handler() interface is used to implement
+** [sqlite3_busy_timeout()] and [PRAGMA busy_timeout].
+**
+** ^If the busy callback is NULL, then [SQLITE_BUSY]
+** is returned immediately upon encountering the lock.  ^If the busy callback
+** is not NULL, then the callback might be invoked with two arguments.
+**
+** ^The first argument to the busy handler is a copy of the void* pointer which
+** is the third argument to sqlite3_busy_handler().  ^The second argument to
+** the busy handler callback is the number of times that the busy handler has
+** been invoked previously for the same locking event.  ^If the
+** busy callback returns 0, then no additional attempts are made to
+** access the database and [SQLITE_BUSY] is returned
+** to the application.
+** ^If the callback returns non-zero, then another attempt
+** is made to access the database and the cycle repeats.
+**
+** The presence of a busy handler does not guarantee that it will be invoked
+** when there is lock contention. ^If SQLite determines that invoking the busy
+** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]
+** to the application instead of invoking the 
+** busy handler.
+** Consider a scenario where one process is holding a read lock that
+** it is trying to promote to a reserved lock and
+** a second process is holding a reserved lock that it is trying
+** to promote to an exclusive lock.  The first process cannot proceed
+** because it is blocked by the second and the second process cannot
+** proceed because it is blocked by the first.  If both processes
+** invoke the busy handlers, neither will make any progress.  Therefore,
+** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
+** will induce the first process to release its read lock and allow
+** the second process to proceed.
+**
+** ^The default busy callback is NULL.
+**
+** ^(There can only be a single busy handler defined for each
+** [database connection].  Setting a new busy handler clears any
+** previously set handler.)^  ^Note that calling [sqlite3_busy_timeout()]
+** or evaluating [PRAGMA busy_timeout=N] will change the
+** busy handler and thus clear any previously set busy handler.
+**
+** The busy callback should not take any actions which modify the
+** database connection that invoked the busy handler.  In other words,
+** the busy handler is not reentrant.  Any such actions
+** result in undefined behavior.
+** 
+** A busy handler must not close the database connection
+** or [prepared statement] that invoked the busy handler.
+*/
+SQLITE_API int sqlite3_busy_handler(sqlite3*,int(*)(void*,int),void*);
+
+/*
+** CAPI3REF: Set A Busy Timeout
+** METHOD: sqlite3
+**
+** ^This routine sets a [sqlite3_busy_handler | busy handler] that sleeps
+** for a specified amount of time when a table is locked.  ^The handler
+** will sleep multiple times until at least "ms" milliseconds of sleeping
+** have accumulated.  ^After at least "ms" milliseconds of sleeping,
+** the handler returns 0 which causes [sqlite3_step()] to return
+** [SQLITE_BUSY].
+**
+** ^Calling this routine with an argument less than or equal to zero
+** turns off all busy handlers.
+**
+** ^(There can only be a single busy handler for a particular
+** [database connection] at any given moment.  If another busy handler
+** was defined  (using [sqlite3_busy_handler()]) prior to calling
+** this routine, that other busy handler is cleared.)^
+**
+** See also:  [PRAGMA busy_timeout]
+*/
+SQLITE_API int sqlite3_busy_timeout(sqlite3*, int ms);
+
+/*
+** CAPI3REF: Convenience Routines For Running Queries
+** METHOD: sqlite3
+**
+** This is a legacy interface that is preserved for backwards compatibility.
+** Use of this interface is not recommended.
+**
+** Definition: A <b>result table</b> is memory data structure created by the
+** [sqlite3_get_table()] interface.  A result table records the
+** complete query results from one or more queries.
+**
+** The table conceptually has a number of rows and columns.  But
+** these numbers are not part of the result table itself.  These
+** numbers are obtained separately.  Let N be the number of rows
+** and M be the number of columns.
+**
+** A result table is an array of pointers to zero-terminated UTF-8 strings.
+** There are (N+1)*M elements in the array.  The first M pointers point
+** to zero-terminated strings that  contain the names of the columns.
+** The remaining entries all point to query results.  NULL values result
+** in NULL pointers.  All other values are in their UTF-8 zero-terminated
+** string representation as returned by [sqlite3_column_text()].
+**
+** A result table might consist of one or more memory allocations.
+** It is not safe to pass a result table directly to [sqlite3_free()].
+** A result table should be deallocated using [sqlite3_free_table()].
+**
+** ^(As an example of the result table format, suppose a query result
+** is as follows:
+**
+** <blockquote><pre>
+**        Name        | Age
+**        -----------------------
+**        Alice       | 43
+**        Bob         | 28
+**        Cindy       | 21
+** </pre></blockquote>
+**
+** There are two column (M==2) and three rows (N==3).  Thus the
+** result table has 8 entries.  Suppose the result table is stored
+** in an array names azResult.  Then azResult holds this content:
+**
+** <blockquote><pre>
+**        azResult&#91;0] = "Name";
+**        azResult&#91;1] = "Age";
+**        azResult&#91;2] = "Alice";
+**        azResult&#91;3] = "43";
+**        azResult&#91;4] = "Bob";
+**        azResult&#91;5] = "28";
+**        azResult&#91;6] = "Cindy";
+**        azResult&#91;7] = "21";
+** </pre></blockquote>)^
+**
+** ^The sqlite3_get_table() function evaluates one or more
+** semicolon-separated SQL statements in the zero-terminated UTF-8
+** string of its 2nd parameter and returns a result table to the
+** pointer given in its 3rd parameter.
+**
+** After the application has finished with the result from sqlite3_get_table(),
+** it must pass the result table pointer to sqlite3_free_table() in order to
+** release the memory that was malloced.  Because of the way the
+** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling
+** function must not try to call [sqlite3_free()] directly.  Only
+** [sqlite3_free_table()] is able to release the memory properly and safely.
+**
+** The sqlite3_get_table() interface is implemented as a wrapper around
+** [sqlite3_exec()].  The sqlite3_get_table() routine does not have access
+** to any internal data structures of SQLite.  It uses only the public
+** interface defined here.  As a consequence, errors that occur in the
+** wrapper layer outside of the internal [sqlite3_exec()] call are not
+** reflected in subsequent calls to [sqlite3_errcode()] or
+** [sqlite3_errmsg()].
+*/
+SQLITE_API int sqlite3_get_table(
+  sqlite3 *db,          /* An open database */
+  const char *zSql,     /* SQL to be evaluated */
+  char ***pazResult,    /* Results of the query */
+  int *pnRow,           /* Number of result rows written here */
+  int *pnColumn,        /* Number of result columns written here */
+  char **pzErrmsg       /* Error msg written here */
+);
+SQLITE_API void sqlite3_free_table(char **result);
+
+/*
+** CAPI3REF: Formatted String Printing Functions
+**
+** These routines are work-alikes of the "printf()" family of functions
+** from the standard C library.
+** These routines understand most of the common K&R formatting options,
+** plus some additional non-standard formats, detailed below.
+** Note that some of the more obscure formatting options from recent
+** C-library standards are omitted from this implementation.
+**
+** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
+** results into memory obtained from [sqlite3_malloc()].
+** The strings returned by these two routines should be
+** released by [sqlite3_free()].  ^Both routines return a
+** NULL pointer if [sqlite3_malloc()] is unable to allocate enough
+** memory to hold the resulting string.
+**
+** ^(The sqlite3_snprintf() routine is similar to "snprintf()" from
+** the standard C library.  The result is written into the
+** buffer supplied as the second parameter whose size is given by
+** the first parameter. Note that the order of the
+** first two parameters is reversed from snprintf().)^  This is an
+** historical accident that cannot be fixed without breaking
+** backwards compatibility.  ^(Note also that sqlite3_snprintf()
+** returns a pointer to its buffer instead of the number of
+** characters actually written into the buffer.)^  We admit that
+** the number of characters written would be a more useful return
+** value but we cannot change the implementation of sqlite3_snprintf()
+** now without breaking compatibility.
+**
+** ^As long as the buffer size is greater than zero, sqlite3_snprintf()
+** guarantees that the buffer is always zero-terminated.  ^The first
+** parameter "n" is the total size of the buffer, including space for
+** the zero terminator.  So the longest string that can be completely
+** written will be n-1 characters.
+**
+** ^The sqlite3_vsnprintf() routine is a varargs version of sqlite3_snprintf().
+**
+** These routines all implement some additional formatting
+** options that are useful for constructing SQL statements.
+** All of the usual printf() formatting options apply.  In addition, there
+** is are "%q", "%Q", "%w" and "%z" options.
+**
+** ^(The %q option works like %s in that it substitutes a nul-terminated
+** string from the argument list.  But %q also doubles every '\'' character.
+** %q is designed for use inside a string literal.)^  By doubling each '\''
+** character it escapes that character and allows it to be inserted into
+** the string.
+**
+** For example, assume the string variable zText contains text as follows:
+**
+** <blockquote><pre>
+**  char *zText = "It's a happy day!";
+** </pre></blockquote>
+**
+** One can use this text in an SQL statement as follows:
+**
+** <blockquote><pre>
+**  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText);
+**  sqlite3_exec(db, zSQL, 0, 0, 0);
+**  sqlite3_free(zSQL);
+** </pre></blockquote>
+**
+** Because the %q format string is used, the '\'' character in zText
+** is escaped and the SQL generated is as follows:
+**
+** <blockquote><pre>
+**  INSERT INTO table1 VALUES('It''s a happy day!')
+** </pre></blockquote>
+**
+** This is correct.  Had we used %s instead of %q, the generated SQL
+** would have looked like this:
+**
+** <blockquote><pre>
+**  INSERT INTO table1 VALUES('It's a happy day!');
+** </pre></blockquote>
+**
+** This second example is an SQL syntax error.  As a general rule you should
+** always use %q instead of %s when inserting text into a string literal.
+**
+** ^(The %Q option works like %q except it also adds single quotes around
+** the outside of the total string.  Additionally, if the parameter in the
+** argument list is a NULL pointer, %Q substitutes the text "NULL" (without
+** single quotes).)^  So, for example, one could say:
+**
+** <blockquote><pre>
+**  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText);
+**  sqlite3_exec(db, zSQL, 0, 0, 0);
+**  sqlite3_free(zSQL);
+** </pre></blockquote>
+**
+** The code above will render a correct SQL statement in the zSQL
+** variable even if the zText variable is a NULL pointer.
+**
+** ^(The "%w" formatting option is like "%q" except that it expects to
+** be contained within double-quotes instead of single quotes, and it
+** escapes the double-quote character instead of the single-quote
+** character.)^  The "%w" formatting option is intended for safely inserting
+** table and column names into a constructed SQL statement.
+**
+** ^(The "%z" formatting option works like "%s" but with the
+** addition that after the string has been read and copied into
+** the result, [sqlite3_free()] is called on the input string.)^
+*/
+SQLITE_API char *sqlite3_mprintf(const char*,...);
+SQLITE_API char *sqlite3_vmprintf(const char*, va_list);
+SQLITE_API char *sqlite3_snprintf(int,char*,const char*, ...);
+SQLITE_API char *sqlite3_vsnprintf(int,char*,const char*, va_list);
+
+/*
+** CAPI3REF: Memory Allocation Subsystem
+**
+** The SQLite core uses these three routines for all of its own
+** internal memory allocation needs. "Core" in the previous sentence
+** does not include operating-system specific VFS implementation.  The
+** Windows VFS uses native malloc() and free() for some operations.
+**
+** ^The sqlite3_malloc() routine returns a pointer to a block
+** of memory at least N bytes in length, where N is the parameter.
+** ^If sqlite3_malloc() is unable to obtain sufficient free
+** memory, it returns a NULL pointer.  ^If the parameter N to
+** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns
+** a NULL pointer.
+**
+** ^The sqlite3_malloc64(N) routine works just like
+** sqlite3_malloc(N) except that N is an unsigned 64-bit integer instead
+** of a signed 32-bit integer.
+**
+** ^Calling sqlite3_free() with a pointer previously returned
+** by sqlite3_malloc() or sqlite3_realloc() releases that memory so
+** that it might be reused.  ^The sqlite3_free() routine is
+** a no-op if is called with a NULL pointer.  Passing a NULL pointer
+** to sqlite3_free() is harmless.  After being freed, memory
+** should neither be read nor written.  Even reading previously freed
+** memory might result in a segmentation fault or other severe error.
+** Memory corruption, a segmentation fault, or other severe error
+** might result if sqlite3_free() is called with a non-NULL pointer that
+** was not obtained from sqlite3_malloc() or sqlite3_realloc().
+**
+** ^The sqlite3_realloc(X,N) interface attempts to resize a
+** prior memory allocation X to be at least N bytes.
+** ^If the X parameter to sqlite3_realloc(X,N)
+** is a NULL pointer then its behavior is identical to calling
+** sqlite3_malloc(N).
+** ^If the N parameter to sqlite3_realloc(X,N) is zero or
+** negative then the behavior is exactly the same as calling
+** sqlite3_free(X).
+** ^sqlite3_realloc(X,N) returns a pointer to a memory allocation
+** of at least N bytes in size or NULL if insufficient memory is available.
+** ^If M is the size of the prior allocation, then min(N,M) bytes
+** of the prior allocation are copied into the beginning of buffer returned
+** by sqlite3_realloc(X,N) and the prior allocation is freed.
+** ^If sqlite3_realloc(X,N) returns NULL and N is positive, then the
+** prior allocation is not freed.
+**
+** ^The sqlite3_realloc64(X,N) interfaces works the same as
+** sqlite3_realloc(X,N) except that N is a 64-bit unsigned integer instead
+** of a 32-bit signed integer.
+**
+** ^If X is a memory allocation previously obtained from sqlite3_malloc(),
+** sqlite3_malloc64(), sqlite3_realloc(), or sqlite3_realloc64(), then
+** sqlite3_msize(X) returns the size of that memory allocation in bytes.
+** ^The value returned by sqlite3_msize(X) might be larger than the number
+** of bytes requested when X was allocated.  ^If X is a NULL pointer then
+** sqlite3_msize(X) returns zero.  If X points to something that is not
+** the beginning of memory allocation, or if it points to a formerly
+** valid memory allocation that has now been freed, then the behavior
+** of sqlite3_msize(X) is undefined and possibly harmful.
+**
+** ^The memory returned by sqlite3_malloc(), sqlite3_realloc(),
+** sqlite3_malloc64(), and sqlite3_realloc64()
+** is always aligned to at least an 8 byte boundary, or to a
+** 4 byte boundary if the [SQLITE_4_BYTE_ALIGNED_MALLOC] compile-time
+** option is used.
+**
+** In SQLite version 3.5.0 and 3.5.1, it was possible to define
+** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in
+** implementation of these routines to be omitted.  That capability
+** is no longer provided.  Only built-in memory allocators can be used.
+**
+** Prior to SQLite version 3.7.10, the Windows OS interface layer called
+** the system malloc() and free() directly when converting
+** filenames between the UTF-8 encoding used by SQLite
+** and whatever filename encoding is used by the particular Windows
+** installation.  Memory allocation errors were detected, but
+** they were reported back as [SQLITE_CANTOPEN] or
+** [SQLITE_IOERR] rather than [SQLITE_NOMEM].
+**
+** The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]
+** must be either NULL or else pointers obtained from a prior
+** invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have
+** not yet been released.
+**
+** The application must not read or write any part of
+** a block of memory after it has been released using
+** [sqlite3_free()] or [sqlite3_realloc()].
+*/
+SQLITE_API void *sqlite3_malloc(int);
+SQLITE_API void *sqlite3_malloc64(sqlite3_uint64);
+SQLITE_API void *sqlite3_realloc(void*, int);
+SQLITE_API void *sqlite3_realloc64(void*, sqlite3_uint64);
+SQLITE_API void sqlite3_free(void*);
+SQLITE_API sqlite3_uint64 sqlite3_msize(void*);
+
+/*
+** CAPI3REF: Memory Allocator Statistics
+**
+** SQLite provides these two interfaces for reporting on the status
+** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]
+** routines, which form the built-in memory allocation subsystem.
+**
+** ^The [sqlite3_memory_used()] routine returns the number of bytes
+** of memory currently outstanding (malloced but not freed).
+** ^The [sqlite3_memory_highwater()] routine returns the maximum
+** value of [sqlite3_memory_used()] since the high-water mark
+** was last reset.  ^The values returned by [sqlite3_memory_used()] and
+** [sqlite3_memory_highwater()] include any overhead
+** added by SQLite in its implementation of [sqlite3_malloc()],
+** but not overhead added by the any underlying system library
+** routines that [sqlite3_malloc()] may call.
+**
+** ^The memory high-water mark is reset to the current value of
+** [sqlite3_memory_used()] if and only if the parameter to
+** [sqlite3_memory_highwater()] is true.  ^The value returned
+** by [sqlite3_memory_highwater(1)] is the high-water mark
+** prior to the reset.
+*/
+SQLITE_API sqlite3_int64 sqlite3_memory_used(void);
+SQLITE_API sqlite3_int64 sqlite3_memory_highwater(int resetFlag);
+
+/*
+** CAPI3REF: Pseudo-Random Number Generator
+**
+** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
+** select random [ROWID | ROWIDs] when inserting new records into a table that
+** already uses the largest possible [ROWID].  The PRNG is also used for
+** the build-in random() and randomblob() SQL functions.  This interface allows
+** applications to access the same PRNG for other purposes.
+**
+** ^A call to this routine stores N bytes of randomness into buffer P.
+** ^The P parameter can be a NULL pointer.
+**
+** ^If this routine has not been previously called or if the previous
+** call had N less than one or a NULL pointer for P, then the PRNG is
+** seeded using randomness obtained from the xRandomness method of
+** the default [sqlite3_vfs] object.
+** ^If the previous call to this routine had an N of 1 or more and a
+** non-NULL P then the pseudo-randomness is generated
+** internally and without recourse to the [sqlite3_vfs] xRandomness
+** method.
+*/
+SQLITE_API void sqlite3_randomness(int N, void *P);
+
+/*
+** CAPI3REF: Compile-Time Authorization Callbacks
+** METHOD: sqlite3
+**
+** ^This routine registers an authorizer callback with a particular
+** [database connection], supplied in the first argument.
+** ^The authorizer callback is invoked as SQL statements are being compiled
+** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
+** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()].  ^At various
+** points during the compilation process, as logic is being created
+** to perform various actions, the authorizer callback is invoked to
+** see if those actions are allowed.  ^The authorizer callback should
+** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the
+** specific action but allow the SQL statement to continue to be
+** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be
+** rejected with an error.  ^If the authorizer callback returns
+** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]
+** then the [sqlite3_prepare_v2()] or equivalent call that triggered
+** the authorizer will fail with an error message.
+**
+** When the callback returns [SQLITE_OK], that means the operation
+** requested is ok.  ^When the callback returns [SQLITE_DENY], the
+** [sqlite3_prepare_v2()] or equivalent call that triggered the
+** authorizer will fail with an error message explaining that
+** access is denied. 
+**
+** ^The first parameter to the authorizer callback is a copy of the third
+** parameter to the sqlite3_set_authorizer() interface. ^The second parameter
+** to the callback is an integer [SQLITE_COPY | action code] that specifies
+** the particular action to be authorized. ^The third through sixth parameters
+** to the callback are zero-terminated strings that contain additional
+** details about the action to be authorized.
+**
+** ^If the action code is [SQLITE_READ]
+** and the callback returns [SQLITE_IGNORE] then the
+** [prepared statement] statement is constructed to substitute
+** a NULL value in place of the table column that would have
+** been read if [SQLITE_OK] had been returned.  The [SQLITE_IGNORE]
+** return can be used to deny an untrusted user access to individual
+** columns of a table.
+** ^If the action code is [SQLITE_DELETE] and the callback returns
+** [SQLITE_IGNORE] then the [DELETE] operation proceeds but the
+** [truncate optimization] is disabled and all rows are deleted individually.
+**
+** An authorizer is used when [sqlite3_prepare | preparing]
+** SQL statements from an untrusted source, to ensure that the SQL statements
+** do not try to access data they are not allowed to see, or that they do not
+** try to execute malicious statements that damage the database.  For
+** example, an application may allow a user to enter arbitrary
+** SQL queries for evaluation by a database.  But the application does
+** not want the user to be able to make arbitrary changes to the
+** database.  An authorizer could then be put in place while the
+** user-entered SQL is being [sqlite3_prepare | prepared] that
+** disallows everything except [SELECT] statements.
+**
+** Applications that need to process SQL from untrusted sources
+** might also consider lowering resource limits using [sqlite3_limit()]
+** and limiting database size using the [max_page_count] [PRAGMA]
+** in addition to using an authorizer.
+**
+** ^(Only a single authorizer can be in place on a database connection
+** at a time.  Each call to sqlite3_set_authorizer overrides the
+** previous call.)^  ^Disable the authorizer by installing a NULL callback.
+** The authorizer is disabled by default.
+**
+** The authorizer callback must not do anything that will modify
+** the database connection that invoked the authorizer callback.
+** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
+** database connections for the meaning of "modify" in this paragraph.
+**
+** ^When [sqlite3_prepare_v2()] is used to prepare a statement, the
+** statement might be re-prepared during [sqlite3_step()] due to a 
+** schema change.  Hence, the application should ensure that the
+** correct authorizer callback remains in place during the [sqlite3_step()].
+**
+** ^Note that the authorizer callback is invoked only during
+** [sqlite3_prepare()] or its variants.  Authorization is not
+** performed during statement evaluation in [sqlite3_step()], unless
+** as stated in the previous paragraph, sqlite3_step() invokes
+** sqlite3_prepare_v2() to reprepare a statement after a schema change.
+*/
+SQLITE_API int sqlite3_set_authorizer(
+  sqlite3*,
+  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
+  void *pUserData
+);
+
+/*
+** CAPI3REF: Authorizer Return Codes
+**
+** The [sqlite3_set_authorizer | authorizer callback function] must
+** return either [SQLITE_OK] or one of these two constants in order
+** to signal SQLite whether or not the action is permitted.  See the
+** [sqlite3_set_authorizer | authorizer documentation] for additional
+** information.
+**
+** Note that SQLITE_IGNORE is also used as a [conflict resolution mode]
+** returned from the [sqlite3_vtab_on_conflict()] interface.
+*/
+#define SQLITE_DENY   1   /* Abort the SQL statement with an error */
+#define SQLITE_IGNORE 2   /* Don't allow access, but don't generate an error */
+
+/*
+** CAPI3REF: Authorizer Action Codes
+**
+** The [sqlite3_set_authorizer()] interface registers a callback function
+** that is invoked to authorize certain SQL statement actions.  The
+** second parameter to the callback is an integer code that specifies
+** what action is being authorized.  These are the integer action codes that
+** the authorizer callback may be passed.
+**
+** These action code values signify what kind of operation is to be
+** authorized.  The 3rd and 4th parameters to the authorization
+** callback function will be parameters or NULL depending on which of these
+** codes is used as the second parameter.  ^(The 5th parameter to the
+** authorizer callback is the name of the database ("main", "temp",
+** etc.) if applicable.)^  ^The 6th parameter to the authorizer callback
+** is the name of the inner-most trigger or view that is responsible for
+** the access attempt or NULL if this access attempt is directly from
+** top-level SQL code.
+*/
+/******************************************* 3rd ************ 4th ***********/
+#define SQLITE_CREATE_INDEX          1   /* Index Name      Table Name      */
+#define SQLITE_CREATE_TABLE          2   /* Table Name      NULL            */
+#define SQLITE_CREATE_TEMP_INDEX     3   /* Index Name      Table Name      */
+#define SQLITE_CREATE_TEMP_TABLE     4   /* Table Name      NULL            */
+#define SQLITE_CREATE_TEMP_TRIGGER   5   /* Trigger Name    Table Name      */
+#define SQLITE_CREATE_TEMP_VIEW      6   /* View Name       NULL            */
+#define SQLITE_CREATE_TRIGGER        7   /* Trigger Name    Table Name      */
+#define SQLITE_CREATE_VIEW           8   /* View Name       NULL            */
+#define SQLITE_DELETE                9   /* Table Name      NULL            */
+#define SQLITE_DROP_INDEX           10   /* Index Name      Table Name      */
+#define SQLITE_DROP_TABLE           11   /* Table Name      NULL            */
+#define SQLITE_DROP_TEMP_INDEX      12   /* Index Name      Table Name      */
+#define SQLITE_DROP_TEMP_TABLE      13   /* Table Name      NULL            */
+#define SQLITE_DROP_TEMP_TRIGGER    14   /* Trigger Name    Table Name      */
+#define SQLITE_DROP_TEMP_VIEW       15   /* View Name       NULL            */
+#define SQLITE_DROP_TRIGGER         16   /* Trigger Name    Table Name      */
+#define SQLITE_DROP_VIEW            17   /* View Name       NULL            */
+#define SQLITE_INSERT               18   /* Table Name      NULL            */
+#define SQLITE_PRAGMA               19   /* Pragma Name     1st arg or NULL */
+#define SQLITE_READ                 20   /* Table Name      Column Name     */
+#define SQLITE_SELECT               21   /* NULL            NULL            */
+#define SQLITE_TRANSACTION          22   /* Operation       NULL            */
+#define SQLITE_UPDATE               23   /* Table Name      Column Name     */
+#define SQLITE_ATTACH               24   /* Filename        NULL            */
+#define SQLITE_DETACH               25   /* Database Name   NULL            */
+#define SQLITE_ALTER_TABLE          26   /* Database Name   Table Name      */
+#define SQLITE_REINDEX              27   /* Index Name      NULL            */
+#define SQLITE_ANALYZE              28   /* Table Name      NULL            */
+#define SQLITE_CREATE_VTABLE        29   /* Table Name      Module Name     */
+#define SQLITE_DROP_VTABLE          30   /* Table Name      Module Name     */
+#define SQLITE_FUNCTION             31   /* NULL            Function Name   */
+#define SQLITE_SAVEPOINT            32   /* Operation       Savepoint Name  */
+#define SQLITE_COPY                  0   /* No longer used */
+#define SQLITE_RECURSIVE            33   /* NULL            NULL            */
+
+/*
+** CAPI3REF: Tracing And Profiling Functions
+** METHOD: sqlite3
+**
+** These routines are deprecated. Use the [sqlite3_trace_v2()] interface
+** instead of the routines described here.
+**
+** These routines register callback functions that can be used for
+** tracing and profiling the execution of SQL statements.
+**
+** ^The callback function registered by sqlite3_trace() is invoked at
+** various times when an SQL statement is being run by [sqlite3_step()].
+** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
+** SQL statement text as the statement first begins executing.
+** ^(Additional sqlite3_trace() callbacks might occur
+** as each triggered subprogram is entered.  The callbacks for triggers
+** contain a UTF-8 SQL comment that identifies the trigger.)^
+**
+** The [SQLITE_TRACE_SIZE_LIMIT] compile-time option can be used to limit
+** the length of [bound parameter] expansion in the output of sqlite3_trace().
+**
+** ^The callback function registered by sqlite3_profile() is invoked
+** as each SQL statement finishes.  ^The profile callback contains
+** the original statement text and an estimate of wall-clock time
+** of how long that statement took to run.  ^The profile callback
+** time is in units of nanoseconds, however the current implementation
+** is only capable of millisecond resolution so the six least significant
+** digits in the time are meaningless.  Future versions of SQLite
+** might provide greater resolution on the profiler callback.  The
+** sqlite3_profile() function is considered experimental and is
+** subject to change in future versions of SQLite.
+*/
+SQLITE_API SQLITE_DEPRECATED void *sqlite3_trace(sqlite3*,
+   void(*xTrace)(void*,const char*), void*);
+SQLITE_API SQLITE_DEPRECATED void *sqlite3_profile(sqlite3*,
+   void(*xProfile)(void*,const char*,sqlite3_uint64), void*);
+
+/*
+** CAPI3REF: SQL Trace Event Codes
+** KEYWORDS: SQLITE_TRACE
+**
+** These constants identify classes of events that can be monitored
+** using the [sqlite3_trace_v2()] tracing logic.  The third argument
+** to [sqlite3_trace_v2()] is an OR-ed combination of one or more of
+** the following constants.  ^The first argument to the trace callback
+** is one of the following constants.
+**
+** New tracing constants may be added in future releases.
+**
+** ^A trace callback has four arguments: xCallback(T,C,P,X).
+** ^The T argument is one of the integer type codes above.
+** ^The C argument is a copy of the context pointer passed in as the
+** fourth argument to [sqlite3_trace_v2()].
+** The P and X arguments are pointers whose meanings depend on T.
+**
+** <dl>
+** [[SQLITE_TRACE_STMT]] <dt>SQLITE_TRACE_STMT</dt>
+** <dd>^An SQLITE_TRACE_STMT callback is invoked when a prepared statement
+** first begins running and possibly at other times during the
+** execution of the prepared statement, such as at the start of each
+** trigger subprogram. ^The P argument is a pointer to the
+** [prepared statement]. ^The X argument is a pointer to a string which
+** is the unexpanded SQL text of the prepared statement or an SQL comment 
+** that indicates the invocation of a trigger.  ^The callback can compute
+** the same text that would have been returned by the legacy [sqlite3_trace()]
+** interface by using the X argument when X begins with "--" and invoking
+** [sqlite3_expanded_sql(P)] otherwise.
+**
+** [[SQLITE_TRACE_PROFILE]] <dt>SQLITE_TRACE_PROFILE</dt>
+** <dd>^An SQLITE_TRACE_PROFILE callback provides approximately the same
+** information as is provided by the [sqlite3_profile()] callback.
+** ^The P argument is a pointer to the [prepared statement] and the
+** X argument points to a 64-bit integer which is the estimated of
+** the number of nanosecond that the prepared statement took to run.
+** ^The SQLITE_TRACE_PROFILE callback is invoked when the statement finishes.
+**
+** [[SQLITE_TRACE_ROW]] <dt>SQLITE_TRACE_ROW</dt>
+** <dd>^An SQLITE_TRACE_ROW callback is invoked whenever a prepared
+** statement generates a single row of result.  
+** ^The P argument is a pointer to the [prepared statement] and the
+** X argument is unused.
+**
+** [[SQLITE_TRACE_CLOSE]] <dt>SQLITE_TRACE_CLOSE</dt>
+** <dd>^An SQLITE_TRACE_CLOSE callback is invoked when a database
+** connection closes.
+** ^The P argument is a pointer to the [database connection] object
+** and the X argument is unused.
+** </dl>
+*/
+#define SQLITE_TRACE_STMT       0x01
+#define SQLITE_TRACE_PROFILE    0x02
+#define SQLITE_TRACE_ROW        0x04
+#define SQLITE_TRACE_CLOSE      0x08
+
+/*
+** CAPI3REF: SQL Trace Hook
+** METHOD: sqlite3
+**
+** ^The sqlite3_trace_v2(D,M,X,P) interface registers a trace callback
+** function X against [database connection] D, using property mask M
+** and context pointer P.  ^If the X callback is
+** NULL or if the M mask is zero, then tracing is disabled.  The
+** M argument should be the bitwise OR-ed combination of
+** zero or more [SQLITE_TRACE] constants.
+**
+** ^Each call to either sqlite3_trace() or sqlite3_trace_v2() overrides 
+** (cancels) any prior calls to sqlite3_trace() or sqlite3_trace_v2().
+**
+** ^The X callback is invoked whenever any of the events identified by 
+** mask M occur.  ^The integer return value from the callback is currently
+** ignored, though this may change in future releases.  Callback
+** implementations should return zero to ensure future compatibility.
+**
+** ^A trace callback is invoked with four arguments: callback(T,C,P,X).
+** ^The T argument is one of the [SQLITE_TRACE]
+** constants to indicate why the callback was invoked.
+** ^The C argument is a copy of the context pointer.
+** The P and X arguments are pointers whose meanings depend on T.
+**
+** The sqlite3_trace_v2() interface is intended to replace the legacy
+** interfaces [sqlite3_trace()] and [sqlite3_profile()], both of which
+** are deprecated.
+*/
+SQLITE_API int sqlite3_trace_v2(
+  sqlite3*,
+  unsigned uMask,
+  int(*xCallback)(unsigned,void*,void*,void*),
+  void *pCtx
+);
+
+/*
+** CAPI3REF: Query Progress Callbacks
+** METHOD: sqlite3
+**
+** ^The sqlite3_progress_handler(D,N,X,P) interface causes the callback
+** function X to be invoked periodically during long running calls to
+** [sqlite3_exec()], [sqlite3_step()] and [sqlite3_get_table()] for
+** database connection D.  An example use for this
+** interface is to keep a GUI updated during a large query.
+**
+** ^The parameter P is passed through as the only parameter to the 
+** callback function X.  ^The parameter N is the approximate number of 
+** [virtual machine instructions] that are evaluated between successive
+** invocations of the callback X.  ^If N is less than one then the progress
+** handler is disabled.
+**
+** ^Only a single progress handler may be defined at one time per
+** [database connection]; setting a new progress handler cancels the
+** old one.  ^Setting parameter X to NULL disables the progress handler.
+** ^The progress handler is also disabled by setting N to a value less
+** than 1.
+**
+** ^If the progress callback returns non-zero, the operation is
+** interrupted.  This feature can be used to implement a
+** "Cancel" button on a GUI progress dialog box.
+**
+** The progress handler callback must not do anything that will modify
+** the database connection that invoked the progress handler.
+** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
+** database connections for the meaning of "modify" in this paragraph.
+**
+*/
+SQLITE_API void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);
+
+/*
+** CAPI3REF: Opening A New Database Connection
+** CONSTRUCTOR: sqlite3
+**
+** ^These routines open an SQLite database file as specified by the 
+** filename argument. ^The filename argument is interpreted as UTF-8 for
+** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
+** order for sqlite3_open16(). ^(A [database connection] handle is usually
+** returned in *ppDb, even if an error occurs.  The only exception is that
+** if SQLite is unable to allocate memory to hold the [sqlite3] object,
+** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]
+** object.)^ ^(If the database is opened (and/or created) successfully, then
+** [SQLITE_OK] is returned.  Otherwise an [error code] is returned.)^ ^The
+** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain
+** an English language description of the error following a failure of any
+** of the sqlite3_open() routines.
+**
+** ^The default encoding will be UTF-8 for databases created using
+** sqlite3_open() or sqlite3_open_v2().  ^The default encoding for databases
+** created using sqlite3_open16() will be UTF-16 in the native byte order.
+**
+** Whether or not an error occurs when it is opened, resources
+** associated with the [database connection] handle should be released by
+** passing it to [sqlite3_close()] when it is no longer required.
+**
+** The sqlite3_open_v2() interface works like sqlite3_open()
+** except that it accepts two additional parameters for additional control
+** over the new database connection.  ^(The flags parameter to
+** sqlite3_open_v2() can take one of
+** the following three values, optionally combined with the 
+** [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX], [SQLITE_OPEN_SHAREDCACHE],
+** [SQLITE_OPEN_PRIVATECACHE], and/or [SQLITE_OPEN_URI] flags:)^
+**
+** <dl>
+** ^(<dt>[SQLITE_OPEN_READONLY]</dt>
+** <dd>The database is opened in read-only mode.  If the database does not
+** already exist, an error is returned.</dd>)^
+**
+** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>
+** <dd>The database is opened for reading and writing if possible, or reading
+** only if the file is write protected by the operating system.  In either
+** case the database must already exist, otherwise an error is returned.</dd>)^
+**
+** ^(<dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
+** <dd>The database is opened for reading and writing, and is created if
+** it does not already exist. This is the behavior that is always used for
+** sqlite3_open() and sqlite3_open16().</dd>)^
+** </dl>
+**
+** If the 3rd parameter to sqlite3_open_v2() is not one of the
+** combinations shown above optionally combined with other
+** [SQLITE_OPEN_READONLY | SQLITE_OPEN_* bits]
+** then the behavior is undefined.
+**
+** ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection
+** opens in the multi-thread [threading mode] as long as the single-thread
+** mode has not been set at compile-time or start-time.  ^If the
+** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens
+** in the serialized [threading mode] unless single-thread was
+** previously selected at compile-time or start-time.
+** ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be
+** eligible to use [shared cache mode], regardless of whether or not shared
+** cache is enabled using [sqlite3_enable_shared_cache()].  ^The
+** [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not
+** participate in [shared cache mode] even if it is enabled.
+**
+** ^The fourth parameter to sqlite3_open_v2() is the name of the
+** [sqlite3_vfs] object that defines the operating system interface that
+** the new database connection should use.  ^If the fourth parameter is
+** a NULL pointer then the default [sqlite3_vfs] object is used.
+**
+** ^If the filename is ":memory:", then a private, temporary in-memory database
+** is created for the connection.  ^This in-memory database will vanish when
+** the database connection is closed.  Future versions of SQLite might
+** make use of additional special filenames that begin with the ":" character.
+** It is recommended that when a database filename actually does begin with
+** a ":" character you should prefix the filename with a pathname such as
+** "./" to avoid ambiguity.
+**
+** ^If the filename is an empty string, then a private, temporary
+** on-disk database will be created.  ^This private database will be
+** automatically deleted as soon as the database connection is closed.
+**
+** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
+**
+** ^If [URI filename] interpretation is enabled, and the filename argument
+** begins with "file:", then the filename is interpreted as a URI. ^URI
+** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
+** set in the fourth argument to sqlite3_open_v2(), or if it has
+** been enabled globally using the [SQLITE_CONFIG_URI] option with the
+** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
+** As of SQLite version 3.7.7, URI filename interpretation is turned off
+** by default, but future releases of SQLite might enable URI filename
+** interpretation by default.  See "[URI filenames]" for additional
+** information.
+**
+** URI filenames are parsed according to RFC 3986. ^If the URI contains an
+** authority, then it must be either an empty string or the string 
+** "localhost". ^If the authority is not an empty string or "localhost", an 
+** error is returned to the caller. ^The fragment component of a URI, if 
+** present, is ignored.
+**
+** ^SQLite uses the path component of the URI as the name of the disk file
+** which contains the database. ^If the path begins with a '/' character, 
+** then it is interpreted as an absolute path. ^If the path does not begin 
+** with a '/' (meaning that the authority section is omitted from the URI)
+** then the path is interpreted as a relative path. 
+** ^(On windows, the first component of an absolute path 
+** is a drive specification (e.g. "C:").)^
+**
+** [[core URI query parameters]]
+** The query component of a URI may contain parameters that are interpreted
+** either by SQLite itself, or by a [VFS | custom VFS implementation].
+** SQLite and its built-in [VFSes] interpret the
+** following query parameters:
+**
+** <ul>
+**   <li> <b>vfs</b>: ^The "vfs" parameter may be used to specify the name of
+**     a VFS object that provides the operating system interface that should
+**     be used to access the database file on disk. ^If this option is set to
+**     an empty string the default VFS object is used. ^Specifying an unknown
+**     VFS is an error. ^If sqlite3_open_v2() is used and the vfs option is
+**     present, then the VFS specified by the option takes precedence over
+**     the value passed as the fourth parameter to sqlite3_open_v2().
+**
+**   <li> <b>mode</b>: ^(The mode parameter may be set to either "ro", "rw",
+**     "rwc", or "memory". Attempting to set it to any other value is
+**     an error)^. 
+**     ^If "ro" is specified, then the database is opened for read-only 
+**     access, just as if the [SQLITE_OPEN_READONLY] flag had been set in the 
+**     third argument to sqlite3_open_v2(). ^If the mode option is set to 
+**     "rw", then the database is opened for read-write (but not create) 
+**     access, as if SQLITE_OPEN_READWRITE (but not SQLITE_OPEN_CREATE) had 
+**     been set. ^Value "rwc" is equivalent to setting both 
+**     SQLITE_OPEN_READWRITE and SQLITE_OPEN_CREATE.  ^If the mode option is
+**     set to "memory" then a pure [in-memory database] that never reads
+**     or writes from disk is used. ^It is an error to specify a value for
+**     the mode parameter that is less restrictive than that specified by
+**     the flags passed in the third parameter to sqlite3_open_v2().
+**
+**   <li> <b>cache</b>: ^The cache parameter may be set to either "shared" or
+**     "private". ^Setting it to "shared" is equivalent to setting the
+**     SQLITE_OPEN_SHAREDCACHE bit in the flags argument passed to
+**     sqlite3_open_v2(). ^Setting the cache parameter to "private" is 
+**     equivalent to setting the SQLITE_OPEN_PRIVATECACHE bit.
+**     ^If sqlite3_open_v2() is used and the "cache" parameter is present in
+**     a URI filename, its value overrides any behavior requested by setting
+**     SQLITE_OPEN_PRIVATECACHE or SQLITE_OPEN_SHAREDCACHE flag.
+**
+**  <li> <b>psow</b>: ^The psow parameter indicates whether or not the
+**     [powersafe overwrite] property does or does not apply to the
+**     storage media on which the database file resides.
+**
+**  <li> <b>nolock</b>: ^The nolock parameter is a boolean query parameter
+**     which if set disables file locking in rollback journal modes.  This
+**     is useful for accessing a database on a filesystem that does not
+**     support locking.  Caution:  Database corruption might result if two
+**     or more processes write to the same database and any one of those
+**     processes uses nolock=1.
+**
+**  <li> <b>immutable</b>: ^The immutable parameter is a boolean query
+**     parameter that indicates that the database file is stored on
+**     read-only media.  ^When immutable is set, SQLite assumes that the
+**     database file cannot be changed, even by a process with higher
+**     privilege, and so the database is opened read-only and all locking
+**     and change detection is disabled.  Caution: Setting the immutable
+**     property on a database file that does in fact change can result
+**     in incorrect query results and/or [SQLITE_CORRUPT] errors.
+**     See also: [SQLITE_IOCAP_IMMUTABLE].
+**       
+** </ul>
+**
+** ^Specifying an unknown parameter in the query component of a URI is not an
+** error.  Future versions of SQLite might understand additional query
+** parameters.  See "[query parameters with special meaning to SQLite]" for
+** additional information.
+**
+** [[URI filename examples]] <h3>URI filename examples</h3>
+**
+** <table border="1" align=center cellpadding=5>
+** <tr><th> URI filenames <th> Results
+** <tr><td> file:data.db <td> 
+**          Open the file "data.db" in the current directory.
+** <tr><td> file:/home/fred/data.db<br>
+**          file:///home/fred/data.db <br> 
+**          file://localhost/home/fred/data.db <br> <td> 
+**          Open the database file "/home/fred/data.db".
+** <tr><td> file://darkstar/home/fred/data.db <td> 
+**          An error. "darkstar" is not a recognized authority.
+** <tr><td style="white-space:nowrap"> 
+**          file:///C:/Documents%20and%20Settings/fred/Desktop/data.db
+**     <td> Windows only: Open the file "data.db" on fred's desktop on drive
+**          C:. Note that the %20 escaping in this example is not strictly 
+**          necessary - space characters can be used literally
+**          in URI filenames.
+** <tr><td> file:data.db?mode=ro&cache=private <td> 
+**          Open file "data.db" in the current directory for read-only access.
+**          Regardless of whether or not shared-cache mode is enabled by
+**          default, use a private cache.
+** <tr><td> file:/home/fred/data.db?vfs=unix-dotfile <td>
+**          Open file "/home/fred/data.db". Use the special VFS "unix-dotfile"
+**          that uses dot-files in place of posix advisory locking.
+** <tr><td> file:data.db?mode=readonly <td> 
+**          An error. "readonly" is not a valid option for the "mode" parameter.
+** </table>
+**
+** ^URI hexadecimal escape sequences (%HH) are supported within the path and
+** query components of a URI. A hexadecimal escape sequence consists of a
+** percent sign - "%" - followed by exactly two hexadecimal digits 
+** specifying an octet value. ^Before the path or query components of a
+** URI filename are interpreted, they are encoded using UTF-8 and all 
+** hexadecimal escape sequences replaced by a single byte containing the
+** corresponding octet. If this process generates an invalid UTF-8 encoding,
+** the results are undefined.
+**
+** <b>Note to Windows users:</b>  The encoding used for the filename argument
+** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever
+** codepage is currently defined.  Filenames containing international
+** characters must be converted to UTF-8 prior to passing them into
+** sqlite3_open() or sqlite3_open_v2().
+**
+** <b>Note to Windows Runtime users:</b>  The temporary directory must be set
+** prior to calling sqlite3_open() or sqlite3_open_v2().  Otherwise, various
+** features that require the use of temporary files may fail.
+**
+** See also: [sqlite3_temp_directory]
+*/
+SQLITE_API int sqlite3_open(
+  const char *filename,   /* Database filename (UTF-8) */
+  sqlite3 **ppDb          /* OUT: SQLite db handle */
+);
+SQLITE_API int sqlite3_open16(
+  const void *filename,   /* Database filename (UTF-16) */
+  sqlite3 **ppDb          /* OUT: SQLite db handle */
+);
+SQLITE_API int sqlite3_open_v2(
+  const char *filename,   /* Database filename (UTF-8) */
+  sqlite3 **ppDb,         /* OUT: SQLite db handle */
+  int flags,              /* Flags */
+  const char *zVfs        /* Name of VFS module to use */
+);
+
+/*
+** CAPI3REF: Obtain Values For URI Parameters
+**
+** These are utility routines, useful to VFS implementations, that check
+** to see if a database file was a URI that contained a specific query 
+** parameter, and if so obtains the value of that query parameter.
+**
+** If F is the database filename pointer passed into the xOpen() method of 
+** a VFS implementation when the flags parameter to xOpen() has one or 
+** more of the [SQLITE_OPEN_URI] or [SQLITE_OPEN_MAIN_DB] bits set and
+** P is the name of the query parameter, then
+** sqlite3_uri_parameter(F,P) returns the value of the P
+** parameter if it exists or a NULL pointer if P does not appear as a 
+** query parameter on F.  If P is a query parameter of F
+** has no explicit value, then sqlite3_uri_parameter(F,P) returns
+** a pointer to an empty string.
+**
+** The sqlite3_uri_boolean(F,P,B) routine assumes that P is a boolean
+** parameter and returns true (1) or false (0) according to the value
+** of P.  The sqlite3_uri_boolean(F,P,B) routine returns true (1) if the
+** value of query parameter P is one of "yes", "true", or "on" in any
+** case or if the value begins with a non-zero number.  The 
+** sqlite3_uri_boolean(F,P,B) routines returns false (0) if the value of
+** query parameter P is one of "no", "false", or "off" in any case or
+** if the value begins with a numeric zero.  If P is not a query
+** parameter on F or if the value of P is does not match any of the
+** above, then sqlite3_uri_boolean(F,P,B) returns (B!=0).
+**
+** The sqlite3_uri_int64(F,P,D) routine converts the value of P into a
+** 64-bit signed integer and returns that integer, or D if P does not
+** exist.  If the value of P is something other than an integer, then
+** zero is returned.
+** 
+** If F is a NULL pointer, then sqlite3_uri_parameter(F,P) returns NULL and
+** sqlite3_uri_boolean(F,P,B) returns B.  If F is not a NULL pointer and
+** is not a database file pathname pointer that SQLite passed into the xOpen
+** VFS method, then the behavior of this routine is undefined and probably
+** undesirable.
+*/
+SQLITE_API const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam);
+SQLITE_API int sqlite3_uri_boolean(const char *zFile, const char *zParam, int bDefault);
+SQLITE_API sqlite3_int64 sqlite3_uri_int64(const char*, const char*, sqlite3_int64);
+
+
+/*
+** CAPI3REF: Error Codes And Messages
+** METHOD: sqlite3
+**
+** ^If the most recent sqlite3_* API call associated with 
+** [database connection] D failed, then the sqlite3_errcode(D) interface
+** returns the numeric [result code] or [extended result code] for that
+** API call.
+** If the most recent API call was successful,
+** then the return value from sqlite3_errcode() is undefined.
+** ^The sqlite3_extended_errcode()
+** interface is the same except that it always returns the 
+** [extended result code] even when extended result codes are
+** disabled.
+**
+** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
+** text that describes the error, as either UTF-8 or UTF-16 respectively.
+** ^(Memory to hold the error message string is managed internally.
+** The application does not need to worry about freeing the result.
+** However, the error string might be overwritten or deallocated by
+** subsequent calls to other SQLite interface functions.)^
+**
+** ^The sqlite3_errstr() interface returns the English-language text
+** that describes the [result code], as UTF-8.
+** ^(Memory to hold the error message string is managed internally
+** and must not be freed by the application)^.
+**
+** When the serialized [threading mode] is in use, it might be the
+** case that a second error occurs on a separate thread in between
+** the time of the first error and the call to these interfaces.
+** When that happens, the second error will be reported since these
+** interfaces always report the most recent result.  To avoid
+** this, each thread can obtain exclusive use of the [database connection] D
+** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
+** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
+** all calls to the interfaces listed here are completed.
+**
+** If an interface fails with SQLITE_MISUSE, that means the interface
+** was invoked incorrectly by the application.  In that case, the
+** error code and message may or may not be set.
+*/
+SQLITE_API int sqlite3_errcode(sqlite3 *db);
+SQLITE_API int sqlite3_extended_errcode(sqlite3 *db);
+SQLITE_API const char *sqlite3_errmsg(sqlite3*);
+SQLITE_API const void *sqlite3_errmsg16(sqlite3*);
+SQLITE_API const char *sqlite3_errstr(int);
+
+/*
+** CAPI3REF: Prepared Statement Object
+** KEYWORDS: {prepared statement} {prepared statements}
+**
+** An instance of this object represents a single SQL statement that
+** has been compiled into binary form and is ready to be evaluated.
+**
+** Think of each SQL statement as a separate computer program.  The
+** original SQL text is source code.  A prepared statement object 
+** is the compiled object code.  All SQL must be converted into a
+** prepared statement before it can be run.
+**
+** The life-cycle of a prepared statement object usually goes like this:
+**
+** <ol>
+** <li> Create the prepared statement object using [sqlite3_prepare_v2()].
+** <li> Bind values to [parameters] using the sqlite3_bind_*()
+**      interfaces.
+** <li> Run the SQL by calling [sqlite3_step()] one or more times.
+** <li> Reset the prepared statement using [sqlite3_reset()] then go back
+**      to step 2.  Do this zero or more times.
+** <li> Destroy the object using [sqlite3_finalize()].
+** </ol>
+*/
+typedef struct sqlite3_stmt sqlite3_stmt;
+
+/*
+** CAPI3REF: Run-time Limits
+** METHOD: sqlite3
+**
+** ^(This interface allows the size of various constructs to be limited
+** on a connection by connection basis.  The first parameter is the
+** [database connection] whose limit is to be set or queried.  The
+** second parameter is one of the [limit categories] that define a
+** class of constructs to be size limited.  The third parameter is the
+** new limit for that construct.)^
+**
+** ^If the new limit is a negative number, the limit is unchanged.
+** ^(For each limit category SQLITE_LIMIT_<i>NAME</i> there is a 
+** [limits | hard upper bound]
+** set at compile-time by a C preprocessor macro called
+** [limits | SQLITE_MAX_<i>NAME</i>].
+** (The "_LIMIT_" in the name is changed to "_MAX_".))^
+** ^Attempts to increase a limit above its hard upper bound are
+** silently truncated to the hard upper bound.
+**
+** ^Regardless of whether or not the limit was changed, the 
+** [sqlite3_limit()] interface returns the prior value of the limit.
+** ^Hence, to find the current value of a limit without changing it,
+** simply invoke this interface with the third parameter set to -1.
+**
+** Run-time limits are intended for use in applications that manage
+** both their own internal database and also databases that are controlled
+** by untrusted external sources.  An example application might be a
+** web browser that has its own databases for storing history and
+** separate databases controlled by JavaScript applications downloaded
+** off the Internet.  The internal databases can be given the
+** large, default limits.  Databases managed by external sources can
+** be given much smaller limits designed to prevent a denial of service
+** attack.  Developers might also want to use the [sqlite3_set_authorizer()]
+** interface to further control untrusted SQL.  The size of the database
+** created by an untrusted script can be contained using the
+** [max_page_count] [PRAGMA].
+**
+** New run-time limit categories may be added in future releases.
+*/
+SQLITE_API int sqlite3_limit(sqlite3*, int id, int newVal);
+
+/*
+** CAPI3REF: Run-Time Limit Categories
+** KEYWORDS: {limit category} {*limit categories}
+**
+** These constants define various performance limits
+** that can be lowered at run-time using [sqlite3_limit()].
+** The synopsis of the meanings of the various limits is shown below.
+** Additional information is available at [limits | Limits in SQLite].
+**
+** <dl>
+** [[SQLITE_LIMIT_LENGTH]] ^(<dt>SQLITE_LIMIT_LENGTH</dt>
+** <dd>The maximum size of any string or BLOB or table row, in bytes.<dd>)^
+**
+** [[SQLITE_LIMIT_SQL_LENGTH]] ^(<dt>SQLITE_LIMIT_SQL_LENGTH</dt>
+** <dd>The maximum length of an SQL statement, in bytes.</dd>)^
+**
+** [[SQLITE_LIMIT_COLUMN]] ^(<dt>SQLITE_LIMIT_COLUMN</dt>
+** <dd>The maximum number of columns in a table definition or in the
+** result set of a [SELECT] or the maximum number of columns in an index
+** or in an ORDER BY or GROUP BY clause.</dd>)^
+**
+** [[SQLITE_LIMIT_EXPR_DEPTH]] ^(<dt>SQLITE_LIMIT_EXPR_DEPTH</dt>
+** <dd>The maximum depth of the parse tree on any expression.</dd>)^
+**
+** [[SQLITE_LIMIT_COMPOUND_SELECT]] ^(<dt>SQLITE_LIMIT_COMPOUND_SELECT</dt>
+** <dd>The maximum number of terms in a compound SELECT statement.</dd>)^
+**
+** [[SQLITE_LIMIT_VDBE_OP]] ^(<dt>SQLITE_LIMIT_VDBE_OP</dt>
+** <dd>The maximum number of instructions in a virtual machine program
+** used to implement an SQL statement.  This limit is not currently
+** enforced, though that might be added in some future release of
+** SQLite.</dd>)^
+**
+** [[SQLITE_LIMIT_FUNCTION_ARG]] ^(<dt>SQLITE_LIMIT_FUNCTION_ARG</dt>
+** <dd>The maximum number of arguments on a function.</dd>)^
+**
+** [[SQLITE_LIMIT_ATTACHED]] ^(<dt>SQLITE_LIMIT_ATTACHED</dt>
+** <dd>The maximum number of [ATTACH | attached databases].)^</dd>
+**
+** [[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]]
+** ^(<dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt>
+** <dd>The maximum length of the pattern argument to the [LIKE] or
+** [GLOB] operators.</dd>)^
+**
+** [[SQLITE_LIMIT_VARIABLE_NUMBER]]
+** ^(<dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt>
+** <dd>The maximum index number of any [parameter] in an SQL statement.)^
+**
+** [[SQLITE_LIMIT_TRIGGER_DEPTH]] ^(<dt>SQLITE_LIMIT_TRIGGER_DEPTH</dt>
+** <dd>The maximum depth of recursion for triggers.</dd>)^
+**
+** [[SQLITE_LIMIT_WORKER_THREADS]] ^(<dt>SQLITE_LIMIT_WORKER_THREADS</dt>
+** <dd>The maximum number of auxiliary worker threads that a single
+** [prepared statement] may start.</dd>)^
+** </dl>
+*/
+#define SQLITE_LIMIT_LENGTH                    0
+#define SQLITE_LIMIT_SQL_LENGTH                1
+#define SQLITE_LIMIT_COLUMN                    2
+#define SQLITE_LIMIT_EXPR_DEPTH                3
+#define SQLITE_LIMIT_COMPOUND_SELECT           4
+#define SQLITE_LIMIT_VDBE_OP                   5
+#define SQLITE_LIMIT_FUNCTION_ARG              6
+#define SQLITE_LIMIT_ATTACHED                  7
+#define SQLITE_LIMIT_LIKE_PATTERN_LENGTH       8
+#define SQLITE_LIMIT_VARIABLE_NUMBER           9
+#define SQLITE_LIMIT_TRIGGER_DEPTH            10
+#define SQLITE_LIMIT_WORKER_THREADS           11
+
+/*
+** CAPI3REF: Compiling An SQL Statement
+** KEYWORDS: {SQL statement compiler}
+** METHOD: sqlite3
+** CONSTRUCTOR: sqlite3_stmt
+**
+** To execute an SQL query, it must first be compiled into a byte-code
+** program using one of these routines.
+**
+** The first argument, "db", is a [database connection] obtained from a
+** prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or
+** [sqlite3_open16()].  The database connection must not have been closed.
+**
+** The second argument, "zSql", is the statement to be compiled, encoded
+** as either UTF-8 or UTF-16.  The sqlite3_prepare() and sqlite3_prepare_v2()
+** interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2()
+** use UTF-16.
+**
+** ^If the nByte argument is negative, then zSql is read up to the
+** first zero terminator. ^If nByte is positive, then it is the
+** number of bytes read from zSql.  ^If nByte is zero, then no prepared
+** statement is generated.
+** If the caller knows that the supplied string is nul-terminated, then
+** there is a small performance advantage to passing an nByte parameter that
+** is the number of bytes in the input string <i>including</i>
+** the nul-terminator.
+**
+** ^If pzTail is not NULL then *pzTail is made to point to the first byte
+** past the end of the first SQL statement in zSql.  These routines only
+** compile the first statement in zSql, so *pzTail is left pointing to
+** what remains uncompiled.
+**
+** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
+** executed using [sqlite3_step()].  ^If there is an error, *ppStmt is set
+** to NULL.  ^If the input text contains no SQL (if the input is an empty
+** string or a comment) then *ppStmt is set to NULL.
+** The calling procedure is responsible for deleting the compiled
+** SQL statement using [sqlite3_finalize()] after it has finished with it.
+** ppStmt may not be NULL.
+**
+** ^On success, the sqlite3_prepare() family of routines return [SQLITE_OK];
+** otherwise an [error code] is returned.
+**
+** The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are
+** recommended for all new programs. The two older interfaces are retained
+** for backwards compatibility, but their use is discouraged.
+** ^In the "v2" interfaces, the prepared statement
+** that is returned (the [sqlite3_stmt] object) contains a copy of the
+** original SQL text. This causes the [sqlite3_step()] interface to
+** behave differently in three ways:
+**
+** <ol>
+** <li>
+** ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it
+** always used to do, [sqlite3_step()] will automatically recompile the SQL
+** statement and try to run it again. As many as [SQLITE_MAX_SCHEMA_RETRY]
+** retries will occur before sqlite3_step() gives up and returns an error.
+** </li>
+**
+** <li>
+** ^When an error occurs, [sqlite3_step()] will return one of the detailed
+** [error codes] or [extended error codes].  ^The legacy behavior was that
+** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code
+** and the application would have to make a second call to [sqlite3_reset()]
+** in order to find the underlying cause of the problem. With the "v2" prepare
+** interfaces, the underlying reason for the error is returned immediately.
+** </li>
+**
+** <li>
+** ^If the specific value bound to [parameter | host parameter] in the 
+** WHERE clause might influence the choice of query plan for a statement,
+** then the statement will be automatically recompiled, as if there had been 
+** a schema change, on the first  [sqlite3_step()] call following any change
+** to the [sqlite3_bind_text | bindings] of that [parameter]. 
+** ^The specific value of WHERE-clause [parameter] might influence the 
+** choice of query plan if the parameter is the left-hand side of a [LIKE]
+** or [GLOB] operator or if the parameter is compared to an indexed column
+** and the [SQLITE_ENABLE_STAT3] compile-time option is enabled.
+** </li>
+** </ol>
+*/
+SQLITE_API int sqlite3_prepare(
+  sqlite3 *db,            /* Database handle */
+  const char *zSql,       /* SQL statement, UTF-8 encoded */
+  int nByte,              /* Maximum length of zSql in bytes. */
+  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
+  const char **pzTail     /* OUT: Pointer to unused portion of zSql */
+);
+SQLITE_API int sqlite3_prepare_v2(
+  sqlite3 *db,            /* Database handle */
+  const char *zSql,       /* SQL statement, UTF-8 encoded */
+  int nByte,              /* Maximum length of zSql in bytes. */
+  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
+  const char **pzTail     /* OUT: Pointer to unused portion of zSql */
+);
+SQLITE_API int sqlite3_prepare16(
+  sqlite3 *db,            /* Database handle */
+  const void *zSql,       /* SQL statement, UTF-16 encoded */
+  int nByte,              /* Maximum length of zSql in bytes. */
+  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
+  const void **pzTail     /* OUT: Pointer to unused portion of zSql */
+);
+SQLITE_API int sqlite3_prepare16_v2(
+  sqlite3 *db,            /* Database handle */
+  const void *zSql,       /* SQL statement, UTF-16 encoded */
+  int nByte,              /* Maximum length of zSql in bytes. */
+  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
+  const void **pzTail     /* OUT: Pointer to unused portion of zSql */
+);
+
+/*
+** CAPI3REF: Retrieving Statement SQL
+** METHOD: sqlite3_stmt
+**
+** ^The sqlite3_sql(P) interface returns a pointer to a copy of the UTF-8
+** SQL text used to create [prepared statement] P if P was
+** created by either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
+** ^The sqlite3_expanded_sql(P) interface returns a pointer to a UTF-8
+** string containing the SQL text of prepared statement P with
+** [bound parameters] expanded.
+**
+** ^(For example, if a prepared statement is created using the SQL
+** text "SELECT $abc,:xyz" and if parameter $abc is bound to integer 2345
+** and parameter :xyz is unbound, then sqlite3_sql() will return
+** the original string, "SELECT $abc,:xyz" but sqlite3_expanded_sql()
+** will return "SELECT 2345,NULL".)^
+**
+** ^The sqlite3_expanded_sql() interface returns NULL if insufficient memory
+** is available to hold the result, or if the result would exceed the
+** the maximum string length determined by the [SQLITE_LIMIT_LENGTH].
+**
+** ^The [SQLITE_TRACE_SIZE_LIMIT] compile-time option limits the size of
+** bound parameter expansions.  ^The [SQLITE_OMIT_TRACE] compile-time
+** option causes sqlite3_expanded_sql() to always return NULL.
+**
+** ^The string returned by sqlite3_sql(P) is managed by SQLite and is
+** automatically freed when the prepared statement is finalized.
+** ^The string returned by sqlite3_expanded_sql(P), on the other hand,
+** is obtained from [sqlite3_malloc()] and must be free by the application
+** by passing it to [sqlite3_free()].
+*/
+SQLITE_API const char *sqlite3_sql(sqlite3_stmt *pStmt);
+SQLITE_API char *sqlite3_expanded_sql(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Determine If An SQL Statement Writes The Database
+** METHOD: sqlite3_stmt
+**
+** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if
+** and only if the [prepared statement] X makes no direct changes to
+** the content of the database file.
+**
+** Note that [application-defined SQL functions] or
+** [virtual tables] might change the database indirectly as a side effect.  
+** ^(For example, if an application defines a function "eval()" that 
+** calls [sqlite3_exec()], then the following SQL statement would
+** change the database file through side-effects:
+**
+** <blockquote><pre>
+**    SELECT eval('DELETE FROM t1') FROM t2;
+** </pre></blockquote>
+**
+** But because the [SELECT] statement does not change the database file
+** directly, sqlite3_stmt_readonly() would still return true.)^
+**
+** ^Transaction control statements such as [BEGIN], [COMMIT], [ROLLBACK],
+** [SAVEPOINT], and [RELEASE] cause sqlite3_stmt_readonly() to return true,
+** since the statements themselves do not actually modify the database but
+** rather they control the timing of when other statements modify the 
+** database.  ^The [ATTACH] and [DETACH] statements also cause
+** sqlite3_stmt_readonly() to return true since, while those statements
+** change the configuration of a database connection, they do not make 
+** changes to the content of the database files on disk.
+*/
+SQLITE_API int sqlite3_stmt_readonly(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Determine If A Prepared Statement Has Been Reset
+** METHOD: sqlite3_stmt
+**
+** ^The sqlite3_stmt_busy(S) interface returns true (non-zero) if the
+** [prepared statement] S has been stepped at least once using 
+** [sqlite3_step(S)] but has neither run to completion (returned
+** [SQLITE_DONE] from [sqlite3_step(S)]) nor
+** been reset using [sqlite3_reset(S)].  ^The sqlite3_stmt_busy(S)
+** interface returns false if S is a NULL pointer.  If S is not a 
+** NULL pointer and is not a pointer to a valid [prepared statement]
+** object, then the behavior is undefined and probably undesirable.
+**
+** This interface can be used in combination [sqlite3_next_stmt()]
+** to locate all prepared statements associated with a database 
+** connection that are in need of being reset.  This can be used,
+** for example, in diagnostic routines to search for prepared 
+** statements that are holding a transaction open.
+*/
+SQLITE_API int sqlite3_stmt_busy(sqlite3_stmt*);
+
+/*
+** CAPI3REF: Dynamically Typed Value Object
+** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value}
+**
+** SQLite uses the sqlite3_value object to represent all values
+** that can be stored in a database table. SQLite uses dynamic typing
+** for the values it stores.  ^Values stored in sqlite3_value objects
+** can be integers, floating point values, strings, BLOBs, or NULL.
+**
+** An sqlite3_value object may be either "protected" or "unprotected".
+** Some interfaces require a protected sqlite3_value.  Other interfaces
+** will accept either a protected or an unprotected sqlite3_value.
+** Every interface that accepts sqlite3_value arguments specifies
+** whether or not it requires a protected sqlite3_value.  The
+** [sqlite3_value_dup()] interface can be used to construct a new 
+** protected sqlite3_value from an unprotected sqlite3_value.
+**
+** The terms "protected" and "unprotected" refer to whether or not
+** a mutex is held.  An internal mutex is held for a protected
+** sqlite3_value object but no mutex is held for an unprotected
+** sqlite3_value object.  If SQLite is compiled to be single-threaded
+** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
+** or if SQLite is run in one of reduced mutex modes 
+** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
+** then there is no distinction between protected and unprotected
+** sqlite3_value objects and they can be used interchangeably.  However,
+** for maximum code portability it is recommended that applications
+** still make the distinction between protected and unprotected
+** sqlite3_value objects even when not strictly required.
+**
+** ^The sqlite3_value objects that are passed as parameters into the
+** implementation of [application-defined SQL functions] are protected.
+** ^The sqlite3_value object returned by
+** [sqlite3_column_value()] is unprotected.
+** Unprotected sqlite3_value objects may only be used with
+** [sqlite3_result_value()] and [sqlite3_bind_value()].
+** The [sqlite3_value_blob | sqlite3_value_type()] family of
+** interfaces require protected sqlite3_value objects.
+*/
+typedef struct Mem sqlite3_value;
+
+/*
+** CAPI3REF: SQL Function Context Object
+**
+** The context in which an SQL function executes is stored in an
+** sqlite3_context object.  ^A pointer to an sqlite3_context object
+** is always first parameter to [application-defined SQL functions].
+** The application-defined SQL function implementation will pass this
+** pointer through into calls to [sqlite3_result_int | sqlite3_result()],
+** [sqlite3_aggregate_context()], [sqlite3_user_data()],
+** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()],
+** and/or [sqlite3_set_auxdata()].
+*/
+typedef struct sqlite3_context sqlite3_context;
+
+/*
+** CAPI3REF: Binding Values To Prepared Statements
+** KEYWORDS: {host parameter} {host parameters} {host parameter name}
+** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding}
+** METHOD: sqlite3_stmt
+**
+** ^(In the SQL statement text input to [sqlite3_prepare_v2()] and its variants,
+** literals may be replaced by a [parameter] that matches one of following
+** templates:
+**
+** <ul>
+** <li>  ?
+** <li>  ?NNN
+** <li>  :VVV
+** <li>  @VVV
+** <li>  $VVV
+** </ul>
+**
+** In the templates above, NNN represents an integer literal,
+** and VVV represents an alphanumeric identifier.)^  ^The values of these
+** parameters (also called "host parameter names" or "SQL parameters")
+** can be set using the sqlite3_bind_*() routines defined here.
+**
+** ^The first argument to the sqlite3_bind_*() routines is always
+** a pointer to the [sqlite3_stmt] object returned from
+** [sqlite3_prepare_v2()] or its variants.
+**
+** ^The second argument is the index of the SQL parameter to be set.
+** ^The leftmost SQL parameter has an index of 1.  ^When the same named
+** SQL parameter is used more than once, second and subsequent
+** occurrences have the same index as the first occurrence.
+** ^The index for named parameters can be looked up using the
+** [sqlite3_bind_parameter_index()] API if desired.  ^The index
+** for "?NNN" parameters is the value of NNN.
+** ^The NNN value must be between 1 and the [sqlite3_limit()]
+** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999).
+**
+** ^The third argument is the value to bind to the parameter.
+** ^If the third parameter to sqlite3_bind_text() or sqlite3_bind_text16()
+** or sqlite3_bind_blob() is a NULL pointer then the fourth parameter
+** is ignored and the end result is the same as sqlite3_bind_null().
+**
+** ^(In those routines that have a fourth argument, its value is the
+** number of bytes in the parameter.  To be clear: the value is the
+** number of <u>bytes</u> in the value, not the number of characters.)^
+** ^If the fourth parameter to sqlite3_bind_text() or sqlite3_bind_text16()
+** is negative, then the length of the string is
+** the number of bytes up to the first zero terminator.
+** If the fourth parameter to sqlite3_bind_blob() is negative, then
+** the behavior is undefined.
+** If a non-negative fourth parameter is provided to sqlite3_bind_text()
+** or sqlite3_bind_text16() or sqlite3_bind_text64() then
+** that parameter must be the byte offset
+** where the NUL terminator would occur assuming the string were NUL
+** terminated.  If any NUL characters occur at byte offsets less than 
+** the value of the fourth parameter then the resulting string value will
+** contain embedded NULs.  The result of expressions involving strings
+** with embedded NULs is undefined.
+**
+** ^The fifth argument to the BLOB and string binding interfaces
+** is a destructor used to dispose of the BLOB or
+** string after SQLite has finished with it.  ^The destructor is called
+** to dispose of the BLOB or string even if the call to bind API fails.
+** ^If the fifth argument is
+** the special value [SQLITE_STATIC], then SQLite assumes that the
+** information is in static, unmanaged space and does not need to be freed.
+** ^If the fifth argument has the value [SQLITE_TRANSIENT], then
+** SQLite makes its own private copy of the data immediately, before
+** the sqlite3_bind_*() routine returns.
+**
+** ^The sixth argument to sqlite3_bind_text64() must be one of
+** [SQLITE_UTF8], [SQLITE_UTF16], [SQLITE_UTF16BE], or [SQLITE_UTF16LE]
+** to specify the encoding of the text in the third parameter.  If
+** the sixth argument to sqlite3_bind_text64() is not one of the
+** allowed values shown above, or if the text encoding is different
+** from the encoding specified by the sixth parameter, then the behavior
+** is undefined.
+**
+** ^The sqlite3_bind_zeroblob() routine binds a BLOB of length N that
+** is filled with zeroes.  ^A zeroblob uses a fixed amount of memory
+** (just an integer to hold its size) while it is being processed.
+** Zeroblobs are intended to serve as placeholders for BLOBs whose
+** content is later written using
+** [sqlite3_blob_open | incremental BLOB I/O] routines.
+** ^A negative value for the zeroblob results in a zero-length BLOB.
+**
+** ^If any of the sqlite3_bind_*() routines are called with a NULL pointer
+** for the [prepared statement] or with a prepared statement for which
+** [sqlite3_step()] has been called more recently than [sqlite3_reset()],
+** then the call will return [SQLITE_MISUSE].  If any sqlite3_bind_()
+** routine is passed a [prepared statement] that has been finalized, the
+** result is undefined and probably harmful.
+**
+** ^Bindings are not cleared by the [sqlite3_reset()] routine.
+** ^Unbound parameters are interpreted as NULL.
+**
+** ^The sqlite3_bind_* routines return [SQLITE_OK] on success or an
+** [error code] if anything goes wrong.
+** ^[SQLITE_TOOBIG] might be returned if the size of a string or BLOB
+** exceeds limits imposed by [sqlite3_limit]([SQLITE_LIMIT_LENGTH]) or
+** [SQLITE_MAX_LENGTH].
+** ^[SQLITE_RANGE] is returned if the parameter
+** index is out of range.  ^[SQLITE_NOMEM] is returned if malloc() fails.
+**
+** See also: [sqlite3_bind_parameter_count()],
+** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()].
+*/
+SQLITE_API int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*));
+SQLITE_API int sqlite3_bind_blob64(sqlite3_stmt*, int, const void*, sqlite3_uint64,
+                        void(*)(void*));
+SQLITE_API int sqlite3_bind_double(sqlite3_stmt*, int, double);
+SQLITE_API int sqlite3_bind_int(sqlite3_stmt*, int, int);
+SQLITE_API int sqlite3_bind_int64(sqlite3_stmt*, int, sqlite3_int64);
+SQLITE_API int sqlite3_bind_null(sqlite3_stmt*, int);
+SQLITE_API int sqlite3_bind_text(sqlite3_stmt*,int,const char*,int,void(*)(void*));
+SQLITE_API int sqlite3_bind_text16(sqlite3_stmt*, int, const void*, int, void(*)(void*));
+SQLITE_API int sqlite3_bind_text64(sqlite3_stmt*, int, const char*, sqlite3_uint64,
+                         void(*)(void*), unsigned char encoding);
+SQLITE_API int sqlite3_bind_value(sqlite3_stmt*, int, const sqlite3_value*);
+SQLITE_API int sqlite3_bind_zeroblob(sqlite3_stmt*, int, int n);
+SQLITE_API int sqlite3_bind_zeroblob64(sqlite3_stmt*, int, sqlite3_uint64);
+
+/*
+** CAPI3REF: Number Of SQL Parameters
+** METHOD: sqlite3_stmt
+**
+** ^This routine can be used to find the number of [SQL parameters]
+** in a [prepared statement].  SQL parameters are tokens of the
+** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as
+** placeholders for values that are [sqlite3_bind_blob | bound]
+** to the parameters at a later time.
+**
+** ^(This routine actually returns the index of the largest (rightmost)
+** parameter. For all forms except ?NNN, this will correspond to the
+** number of unique parameters.  If parameters of the ?NNN form are used,
+** there may be gaps in the list.)^
+**
+** See also: [sqlite3_bind_blob|sqlite3_bind()],
+** [sqlite3_bind_parameter_name()], and
+** [sqlite3_bind_parameter_index()].
+*/
+SQLITE_API int sqlite3_bind_parameter_count(sqlite3_stmt*);
+
+/*
+** CAPI3REF: Name Of A Host Parameter
+** METHOD: sqlite3_stmt
+**
+** ^The sqlite3_bind_parameter_name(P,N) interface returns
+** the name of the N-th [SQL parameter] in the [prepared statement] P.
+** ^(SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA"
+** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA"
+** respectively.
+** In other words, the initial ":" or "$" or "@" or "?"
+** is included as part of the name.)^
+** ^Parameters of the form "?" without a following integer have no name
+** and are referred to as "nameless" or "anonymous parameters".
+**
+** ^The first host parameter has an index of 1, not 0.
+**
+** ^If the value N is out of range or if the N-th parameter is
+** nameless, then NULL is returned.  ^The returned string is
+** always in UTF-8 encoding even if the named parameter was
+** originally specified as UTF-16 in [sqlite3_prepare16()] or
+** [sqlite3_prepare16_v2()].
+**
+** See also: [sqlite3_bind_blob|sqlite3_bind()],
+** [sqlite3_bind_parameter_count()], and
+** [sqlite3_bind_parameter_index()].
+*/
+SQLITE_API const char *sqlite3_bind_parameter_name(sqlite3_stmt*, int);
+
+/*
+** CAPI3REF: Index Of A Parameter With A Given Name
+** METHOD: sqlite3_stmt
+**
+** ^Return the index of an SQL parameter given its name.  ^The
+** index value returned is suitable for use as the second
+** parameter to [sqlite3_bind_blob|sqlite3_bind()].  ^A zero
+** is returned if no matching parameter is found.  ^The parameter
+** name must be given in UTF-8 even if the original statement
+** was prepared from UTF-16 text using [sqlite3_prepare16_v2()].
+**
+** See also: [sqlite3_bind_blob|sqlite3_bind()],
+** [sqlite3_bind_parameter_count()], and
+** [sqlite3_bind_parameter_name()].
+*/
+SQLITE_API int sqlite3_bind_parameter_index(sqlite3_stmt*, const char *zName);
+
+/*
+** CAPI3REF: Reset All Bindings On A Prepared Statement
+** METHOD: sqlite3_stmt
+**
+** ^Contrary to the intuition of many, [sqlite3_reset()] does not reset
+** the [sqlite3_bind_blob | bindings] on a [prepared statement].
+** ^Use this routine to reset all host parameters to NULL.
+*/
+SQLITE_API int sqlite3_clear_bindings(sqlite3_stmt*);
+
+/*
+** CAPI3REF: Number Of Columns In A Result Set
+** METHOD: sqlite3_stmt
+**
+** ^Return the number of columns in the result set returned by the
+** [prepared statement]. ^This routine returns 0 if pStmt is an SQL
+** statement that does not return data (for example an [UPDATE]).
+**
+** See also: [sqlite3_data_count()]
+*/
+SQLITE_API int sqlite3_column_count(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Column Names In A Result Set
+** METHOD: sqlite3_stmt
+**
+** ^These routines return the name assigned to a particular column
+** in the result set of a [SELECT] statement.  ^The sqlite3_column_name()
+** interface returns a pointer to a zero-terminated UTF-8 string
+** and sqlite3_column_name16() returns a pointer to a zero-terminated
+** UTF-16 string.  ^The first parameter is the [prepared statement]
+** that implements the [SELECT] statement. ^The second parameter is the
+** column number.  ^The leftmost column is number 0.
+**
+** ^The returned string pointer is valid until either the [prepared statement]
+** is destroyed by [sqlite3_finalize()] or until the statement is automatically
+** reprepared by the first call to [sqlite3_step()] for a particular run
+** or until the next call to
+** sqlite3_column_name() or sqlite3_column_name16() on the same column.
+**
+** ^If sqlite3_malloc() fails during the processing of either routine
+** (for example during a conversion from UTF-8 to UTF-16) then a
+** NULL pointer is returned.
+**
+** ^The name of a result column is the value of the "AS" clause for
+** that column, if there is an AS clause.  If there is no AS clause
+** then the name of the column is unspecified and may change from
+** one release of SQLite to the next.
+*/
+SQLITE_API const char *sqlite3_column_name(sqlite3_stmt*, int N);
+SQLITE_API const void *sqlite3_column_name16(sqlite3_stmt*, int N);
+
+/*
+** CAPI3REF: Source Of Data In A Query Result
+** METHOD: sqlite3_stmt
+**
+** ^These routines provide a means to determine the database, table, and
+** table column that is the origin of a particular result column in
+** [SELECT] statement.
+** ^The name of the database or table or column can be returned as
+** either a UTF-8 or UTF-16 string.  ^The _database_ routines return
+** the database name, the _table_ routines return the table name, and
+** the origin_ routines return the column name.
+** ^The returned string is valid until the [prepared statement] is destroyed
+** using [sqlite3_finalize()] or until the statement is automatically
+** reprepared by the first call to [sqlite3_step()] for a particular run
+** or until the same information is requested
+** again in a different encoding.
+**
+** ^The names returned are the original un-aliased names of the
+** database, table, and column.
+**
+** ^The first argument to these interfaces is a [prepared statement].
+** ^These functions return information about the Nth result column returned by
+** the statement, where N is the second function argument.
+** ^The left-most column is column 0 for these routines.
+**
+** ^If the Nth column returned by the statement is an expression or
+** subquery and is not a column value, then all of these functions return
+** NULL.  ^These routine might also return NULL if a memory allocation error
+** occurs.  ^Otherwise, they return the name of the attached database, table,
+** or column that query result column was extracted from.
+**
+** ^As with all other SQLite APIs, those whose names end with "16" return
+** UTF-16 encoded strings and the other functions return UTF-8.
+**
+** ^These APIs are only available if the library was compiled with the
+** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol.
+**
+** If two or more threads call one or more of these routines against the same
+** prepared statement and column at the same time then the results are
+** undefined.
+**
+** If two or more threads call one or more
+** [sqlite3_column_database_name | column metadata interfaces]
+** for the same [prepared statement] and result column
+** at the same time then the results are undefined.
+*/
+SQLITE_API const char *sqlite3_column_database_name(sqlite3_stmt*,int);
+SQLITE_API const void *sqlite3_column_database_name16(sqlite3_stmt*,int);
+SQLITE_API const char *sqlite3_column_table_name(sqlite3_stmt*,int);
+SQLITE_API const void *sqlite3_column_table_name16(sqlite3_stmt*,int);
+SQLITE_API const char *sqlite3_column_origin_name(sqlite3_stmt*,int);
+SQLITE_API const void *sqlite3_column_origin_name16(sqlite3_stmt*,int);
+
+/*
+** CAPI3REF: Declared Datatype Of A Query Result
+** METHOD: sqlite3_stmt
+**
+** ^(The first parameter is a [prepared statement].
+** If this statement is a [SELECT] statement and the Nth column of the
+** returned result set of that [SELECT] is a table column (not an
+** expression or subquery) then the declared type of the table
+** column is returned.)^  ^If the Nth column of the result set is an
+** expression or subquery, then a NULL pointer is returned.
+** ^The returned string is always UTF-8 encoded.
+**
+** ^(For example, given the database schema:
+**
+** CREATE TABLE t1(c1 VARIANT);
+**
+** and the following statement to be compiled:
+**
+** SELECT c1 + 1, c1 FROM t1;
+**
+** this routine would return the string "VARIANT" for the second result
+** column (i==1), and a NULL pointer for the first result column (i==0).)^
+**
+** ^SQLite uses dynamic run-time typing.  ^So just because a column
+** is declared to contain a particular type does not mean that the
+** data stored in that column is of the declared type.  SQLite is
+** strongly typed, but the typing is dynamic not static.  ^Type
+** is associated with individual values, not with the containers
+** used to hold those values.
+*/
+SQLITE_API const char *sqlite3_column_decltype(sqlite3_stmt*,int);
+SQLITE_API const void *sqlite3_column_decltype16(sqlite3_stmt*,int);
+
+/*
+** CAPI3REF: Evaluate An SQL Statement
+** METHOD: sqlite3_stmt
+**
+** After a [prepared statement] has been prepared using either
+** [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] or one of the legacy
+** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function
+** must be called one or more times to evaluate the statement.
+**
+** The details of the behavior of the sqlite3_step() interface depend
+** on whether the statement was prepared using the newer "v2" interface
+** [sqlite3_prepare_v2()] and [sqlite3_prepare16_v2()] or the older legacy
+** interface [sqlite3_prepare()] and [sqlite3_prepare16()].  The use of the
+** new "v2" interface is recommended for new applications but the legacy
+** interface will continue to be supported.
+**
+** ^In the legacy interface, the return value will be either [SQLITE_BUSY],
+** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
+** ^With the "v2" interface, any of the other [result codes] or
+** [extended result codes] might be returned as well.
+**
+** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
+** database locks it needs to do its job.  ^If the statement is a [COMMIT]
+** or occurs outside of an explicit transaction, then you can retry the
+** statement.  If the statement is not a [COMMIT] and occurs within an
+** explicit transaction then you should rollback the transaction before
+** continuing.
+**
+** ^[SQLITE_DONE] means that the statement has finished executing
+** successfully.  sqlite3_step() should not be called again on this virtual
+** machine without first calling [sqlite3_reset()] to reset the virtual
+** machine back to its initial state.
+**
+** ^If the SQL statement being executed returns any data, then [SQLITE_ROW]
+** is returned each time a new row of data is ready for processing by the
+** caller. The values may be accessed using the [column access functions].
+** sqlite3_step() is called again to retrieve the next row of data.
+**
+** ^[SQLITE_ERROR] means that a run-time error (such as a constraint
+** violation) has occurred.  sqlite3_step() should not be called again on
+** the VM. More information may be found by calling [sqlite3_errmsg()].
+** ^With the legacy interface, a more specific error code (for example,
+** [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth)
+** can be obtained by calling [sqlite3_reset()] on the
+** [prepared statement].  ^In the "v2" interface,
+** the more specific error code is returned directly by sqlite3_step().
+**
+** [SQLITE_MISUSE] means that the this routine was called inappropriately.
+** Perhaps it was called on a [prepared statement] that has
+** already been [sqlite3_finalize | finalized] or on one that had
+** previously returned [SQLITE_ERROR] or [SQLITE_DONE].  Or it could
+** be the case that the same database connection is being used by two or
+** more threads at the same moment in time.
+**
+** For all versions of SQLite up to and including 3.6.23.1, a call to
+** [sqlite3_reset()] was required after sqlite3_step() returned anything
+** other than [SQLITE_ROW] before any subsequent invocation of
+** sqlite3_step().  Failure to reset the prepared statement using 
+** [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from
+** sqlite3_step().  But after [version 3.6.23.1] ([dateof:3.6.23.1],
+** sqlite3_step() began
+** calling [sqlite3_reset()] automatically in this circumstance rather
+** than returning [SQLITE_MISUSE].  This is not considered a compatibility
+** break because any application that ever receives an SQLITE_MISUSE error
+** is broken by definition.  The [SQLITE_OMIT_AUTORESET] compile-time option
+** can be used to restore the legacy behavior.
+**
+** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
+** API always returns a generic error code, [SQLITE_ERROR], following any
+** error other than [SQLITE_BUSY] and [SQLITE_MISUSE].  You must call
+** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
+** specific [error codes] that better describes the error.
+** We admit that this is a goofy design.  The problem has been fixed
+** with the "v2" interface.  If you prepare all of your SQL statements
+** using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead
+** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,
+** then the more specific [error codes] are returned directly
+** by sqlite3_step().  The use of the "v2" interface is recommended.
+*/
+SQLITE_API int sqlite3_step(sqlite3_stmt*);
+
+/*
+** CAPI3REF: Number of columns in a result set
+** METHOD: sqlite3_stmt
+**
+** ^The sqlite3_data_count(P) interface returns the number of columns in the
+** current row of the result set of [prepared statement] P.
+** ^If prepared statement P does not have results ready to return
+** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
+** interfaces) then sqlite3_data_count(P) returns 0.
+** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.
+** ^The sqlite3_data_count(P) routine returns 0 if the previous call to
+** [sqlite3_step](P) returned [SQLITE_DONE].  ^The sqlite3_data_count(P)
+** will return non-zero if previous call to [sqlite3_step](P) returned
+** [SQLITE_ROW], except in the case of the [PRAGMA incremental_vacuum]
+** where it always returns zero since each step of that multi-step
+** pragma returns 0 columns of data.
+**
+** See also: [sqlite3_column_count()]
+*/
+SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Fundamental Datatypes
+** KEYWORDS: SQLITE_TEXT
+**
+** ^(Every value in SQLite has one of five fundamental datatypes:
+**
+** <ul>
+** <li> 64-bit signed integer
+** <li> 64-bit IEEE floating point number
+** <li> string
+** <li> BLOB
+** <li> NULL
+** </ul>)^
+**
+** These constants are codes for each of those types.
+**
+** Note that the SQLITE_TEXT constant was also used in SQLite version 2
+** for a completely different meaning.  Software that links against both
+** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not
+** SQLITE_TEXT.
+*/
+#define SQLITE_INTEGER  1
+#define SQLITE_FLOAT    2
+#define SQLITE_BLOB     4
+#define SQLITE_NULL     5
+#ifdef SQLITE_TEXT
+# undef SQLITE_TEXT
+#else
+# define SQLITE_TEXT     3
+#endif
+#define SQLITE3_TEXT     3
+
+/*
+** CAPI3REF: Result Values From A Query
+** KEYWORDS: {column access functions}
+** METHOD: sqlite3_stmt
+**
+** ^These routines return information about a single column of the current
+** result row of a query.  ^In every case the first argument is a pointer
+** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*]
+** that was returned from [sqlite3_prepare_v2()] or one of its variants)
+** and the second argument is the index of the column for which information
+** should be returned. ^The leftmost column of the result set has the index 0.
+** ^The number of columns in the result can be determined using
+** [sqlite3_column_count()].
+**
+** If the SQL statement does not currently point to a valid row, or if the
+** column index is out of range, the result is undefined.
+** These routines may only be called when the most recent call to
+** [sqlite3_step()] has returned [SQLITE_ROW] and neither
+** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently.
+** If any of these routines are called after [sqlite3_reset()] or
+** [sqlite3_finalize()] or after [sqlite3_step()] has returned
+** something other than [SQLITE_ROW], the results are undefined.
+** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()]
+** are called from a different thread while any of these routines
+** are pending, then the results are undefined.
+**
+** ^The sqlite3_column_type() routine returns the
+** [SQLITE_INTEGER | datatype code] for the initial data type
+** of the result column.  ^The returned value is one of [SQLITE_INTEGER],
+** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL].  The value
+** returned by sqlite3_column_type() is only meaningful if no type
+** conversions have occurred as described below.  After a type conversion,
+** the value returned by sqlite3_column_type() is undefined.  Future
+** versions of SQLite may change the behavior of sqlite3_column_type()
+** following a type conversion.
+**
+** ^If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes()
+** routine returns the number of bytes in that BLOB or string.
+** ^If the result is a UTF-16 string, then sqlite3_column_bytes() converts
+** the string to UTF-8 and then returns the number of bytes.
+** ^If the result is a numeric value then sqlite3_column_bytes() uses
+** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns
+** the number of bytes in that string.
+** ^If the result is NULL, then sqlite3_column_bytes() returns zero.
+**
+** ^If the result is a BLOB or UTF-16 string then the sqlite3_column_bytes16()
+** routine returns the number of bytes in that BLOB or string.
+** ^If the result is a UTF-8 string, then sqlite3_column_bytes16() converts
+** the string to UTF-16 and then returns the number of bytes.
+** ^If the result is a numeric value then sqlite3_column_bytes16() uses
+** [sqlite3_snprintf()] to convert that value to a UTF-16 string and returns
+** the number of bytes in that string.
+** ^If the result is NULL, then sqlite3_column_bytes16() returns zero.
+**
+** ^The values returned by [sqlite3_column_bytes()] and 
+** [sqlite3_column_bytes16()] do not include the zero terminators at the end
+** of the string.  ^For clarity: the values returned by
+** [sqlite3_column_bytes()] and [sqlite3_column_bytes16()] are the number of
+** bytes in the string, not the number of characters.
+**
+** ^Strings returned by sqlite3_column_text() and sqlite3_column_text16(),
+** even empty strings, are always zero-terminated.  ^The return
+** value from sqlite3_column_blob() for a zero-length BLOB is a NULL pointer.
+**
+** <b>Warning:</b> ^The object returned by [sqlite3_column_value()] is an
+** [unprotected sqlite3_value] object.  In a multithreaded environment,
+** an unprotected sqlite3_value object may only be used safely with
+** [sqlite3_bind_value()] and [sqlite3_result_value()].
+** If the [unprotected sqlite3_value] object returned by
+** [sqlite3_column_value()] is used in any other way, including calls
+** to routines like [sqlite3_value_int()], [sqlite3_value_text()],
+** or [sqlite3_value_bytes()], the behavior is not threadsafe.
+**
+** These routines attempt to convert the value where appropriate.  ^For
+** example, if the internal representation is FLOAT and a text result
+** is requested, [sqlite3_snprintf()] is used internally to perform the
+** conversion automatically.  ^(The following table details the conversions
+** that are applied:
+**
+** <blockquote>
+** <table border="1">
+** <tr><th> Internal<br>Type <th> Requested<br>Type <th>  Conversion
+**
+** <tr><td>  NULL    <td> INTEGER   <td> Result is 0
+** <tr><td>  NULL    <td>  FLOAT    <td> Result is 0.0
+** <tr><td>  NULL    <td>   TEXT    <td> Result is a NULL pointer
+** <tr><td>  NULL    <td>   BLOB    <td> Result is a NULL pointer
+** <tr><td> INTEGER  <td>  FLOAT    <td> Convert from integer to float
+** <tr><td> INTEGER  <td>   TEXT    <td> ASCII rendering of the integer
+** <tr><td> INTEGER  <td>   BLOB    <td> Same as INTEGER->TEXT
+** <tr><td>  FLOAT   <td> INTEGER   <td> [CAST] to INTEGER
+** <tr><td>  FLOAT   <td>   TEXT    <td> ASCII rendering of the float
+** <tr><td>  FLOAT   <td>   BLOB    <td> [CAST] to BLOB
+** <tr><td>  TEXT    <td> INTEGER   <td> [CAST] to INTEGER
+** <tr><td>  TEXT    <td>  FLOAT    <td> [CAST] to REAL
+** <tr><td>  TEXT    <td>   BLOB    <td> No change
+** <tr><td>  BLOB    <td> INTEGER   <td> [CAST] to INTEGER
+** <tr><td>  BLOB    <td>  FLOAT    <td> [CAST] to REAL
+** <tr><td>  BLOB    <td>   TEXT    <td> Add a zero terminator if needed
+** </table>
+** </blockquote>)^
+**
+** Note that when type conversions occur, pointers returned by prior
+** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or
+** sqlite3_column_text16() may be invalidated.
+** Type conversions and pointer invalidations might occur
+** in the following cases:
+**
+** <ul>
+** <li> The initial content is a BLOB and sqlite3_column_text() or
+**      sqlite3_column_text16() is called.  A zero-terminator might
+**      need to be added to the string.</li>
+** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or
+**      sqlite3_column_text16() is called.  The content must be converted
+**      to UTF-16.</li>
+** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or
+**      sqlite3_column_text() is called.  The content must be converted
+**      to UTF-8.</li>
+** </ul>
+**
+** ^Conversions between UTF-16be and UTF-16le are always done in place and do
+** not invalidate a prior pointer, though of course the content of the buffer
+** that the prior pointer references will have been modified.  Other kinds
+** of conversion are done in place when it is possible, but sometimes they
+** are not possible and in those cases prior pointers are invalidated.
+**
+** The safest policy is to invoke these routines
+** in one of the following ways:
+**
+** <ul>
+**  <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li>
+**  <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li>
+**  <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li>
+** </ul>
+**
+** In other words, you should call sqlite3_column_text(),
+** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result
+** into the desired format, then invoke sqlite3_column_bytes() or
+** sqlite3_column_bytes16() to find the size of the result.  Do not mix calls
+** to sqlite3_column_text() or sqlite3_column_blob() with calls to
+** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16()
+** with calls to sqlite3_column_bytes().
+**
+** ^The pointers returned are valid until a type conversion occurs as
+** described above, or until [sqlite3_step()] or [sqlite3_reset()] or
+** [sqlite3_finalize()] is called.  ^The memory space used to hold strings
+** and BLOBs is freed automatically.  Do <em>not</em> pass the pointers returned
+** from [sqlite3_column_blob()], [sqlite3_column_text()], etc. into
+** [sqlite3_free()].
+**
+** ^(If a memory allocation error occurs during the evaluation of any
+** of these routines, a default value is returned.  The default value
+** is either the integer 0, the floating point number 0.0, or a NULL
+** pointer.  Subsequent calls to [sqlite3_errcode()] will return
+** [SQLITE_NOMEM].)^
+*/
+SQLITE_API const void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
+SQLITE_API int sqlite3_column_bytes(sqlite3_stmt*, int iCol);
+SQLITE_API int sqlite3_column_bytes16(sqlite3_stmt*, int iCol);
+SQLITE_API double sqlite3_column_double(sqlite3_stmt*, int iCol);
+SQLITE_API int sqlite3_column_int(sqlite3_stmt*, int iCol);
+SQLITE_API sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);
+SQLITE_API const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol);
+SQLITE_API const void *sqlite3_column_text16(sqlite3_stmt*, int iCol);
+SQLITE_API int sqlite3_column_type(sqlite3_stmt*, int iCol);
+SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);
+
+/*
+** CAPI3REF: Destroy A Prepared Statement Object
+** DESTRUCTOR: sqlite3_stmt
+**
+** ^The sqlite3_finalize() function is called to delete a [prepared statement].
+** ^If the most recent evaluation of the statement encountered no errors
+** or if the statement is never been evaluated, then sqlite3_finalize() returns
+** SQLITE_OK.  ^If the most recent evaluation of statement S failed, then
+** sqlite3_finalize(S) returns the appropriate [error code] or
+** [extended error code].
+**
+** ^The sqlite3_finalize(S) routine can be called at any point during
+** the life cycle of [prepared statement] S:
+** before statement S is ever evaluated, after
+** one or more calls to [sqlite3_reset()], or after any call
+** to [sqlite3_step()] regardless of whether or not the statement has
+** completed execution.
+**
+** ^Invoking sqlite3_finalize() on a NULL pointer is a harmless no-op.
+**
+** The application must finalize every [prepared statement] in order to avoid
+** resource leaks.  It is a grievous error for the application to try to use
+** a prepared statement after it has been finalized.  Any use of a prepared
+** statement after it has been finalized can result in undefined and
+** undesirable behavior such as segfaults and heap corruption.
+*/
+SQLITE_API int sqlite3_finalize(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Reset A Prepared Statement Object
+** METHOD: sqlite3_stmt
+**
+** The sqlite3_reset() function is called to reset a [prepared statement]
+** object back to its initial state, ready to be re-executed.
+** ^Any SQL statement variables that had values bound to them using
+** the [sqlite3_bind_blob | sqlite3_bind_*() API] retain their values.
+** Use [sqlite3_clear_bindings()] to reset the bindings.
+**
+** ^The [sqlite3_reset(S)] interface resets the [prepared statement] S
+** back to the beginning of its program.
+**
+** ^If the most recent call to [sqlite3_step(S)] for the
+** [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE],
+** or if [sqlite3_step(S)] has never before been called on S,
+** then [sqlite3_reset(S)] returns [SQLITE_OK].
+**
+** ^If the most recent call to [sqlite3_step(S)] for the
+** [prepared statement] S indicated an error, then
+** [sqlite3_reset(S)] returns an appropriate [error code].
+**
+** ^The [sqlite3_reset(S)] interface does not change the values
+** of any [sqlite3_bind_blob|bindings] on the [prepared statement] S.
+*/
+SQLITE_API int sqlite3_reset(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Create Or Redefine SQL Functions
+** KEYWORDS: {function creation routines}
+** KEYWORDS: {application-defined SQL function}
+** KEYWORDS: {application-defined SQL functions}
+** METHOD: sqlite3
+**
+** ^These functions (collectively known as "function creation routines")
+** are used to add SQL functions or aggregates or to redefine the behavior
+** of existing SQL functions or aggregates.  The only differences between
+** these routines are the text encoding expected for
+** the second parameter (the name of the function being created)
+** and the presence or absence of a destructor callback for
+** the application data pointer.
+**
+** ^The first parameter is the [database connection] to which the SQL
+** function is to be added.  ^If an application uses more than one database
+** connection then application-defined SQL functions must be added
+** to each database connection separately.
+**
+** ^The second parameter is the name of the SQL function to be created or
+** redefined.  ^The length of the name is limited to 255 bytes in a UTF-8
+** representation, exclusive of the zero-terminator.  ^Note that the name
+** length limit is in UTF-8 bytes, not characters nor UTF-16 bytes.  
+** ^Any attempt to create a function with a longer name
+** will result in [SQLITE_MISUSE] being returned.
+**
+** ^The third parameter (nArg)
+** is the number of arguments that the SQL function or
+** aggregate takes. ^If this parameter is -1, then the SQL function or
+** aggregate may take any number of arguments between 0 and the limit
+** set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]).  If the third
+** parameter is less than -1 or greater than 127 then the behavior is
+** undefined.
+**
+** ^The fourth parameter, eTextRep, specifies what
+** [SQLITE_UTF8 | text encoding] this SQL function prefers for
+** its parameters.  The application should set this parameter to
+** [SQLITE_UTF16LE] if the function implementation invokes 
+** [sqlite3_value_text16le()] on an input, or [SQLITE_UTF16BE] if the
+** implementation invokes [sqlite3_value_text16be()] on an input, or
+** [SQLITE_UTF16] if [sqlite3_value_text16()] is used, or [SQLITE_UTF8]
+** otherwise.  ^The same SQL function may be registered multiple times using
+** different preferred text encodings, with different implementations for
+** each encoding.
+** ^When multiple implementations of the same function are available, SQLite
+** will pick the one that involves the least amount of data conversion.
+**
+** ^The fourth parameter may optionally be ORed with [SQLITE_DETERMINISTIC]
+** to signal that the function will always return the same result given
+** the same inputs within a single SQL statement.  Most SQL functions are
+** deterministic.  The built-in [random()] SQL function is an example of a
+** function that is not deterministic.  The SQLite query planner is able to
+** perform additional optimizations on deterministic functions, so use
+** of the [SQLITE_DETERMINISTIC] flag is recommended where possible.
+**
+** ^(The fifth parameter is an arbitrary pointer.  The implementation of the
+** function can gain access to this pointer using [sqlite3_user_data()].)^
+**
+** ^The sixth, seventh and eighth parameters, xFunc, xStep and xFinal, are
+** pointers to C-language functions that implement the SQL function or
+** aggregate. ^A scalar SQL function requires an implementation of the xFunc
+** callback only; NULL pointers must be passed as the xStep and xFinal
+** parameters. ^An aggregate SQL function requires an implementation of xStep
+** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing
+** SQL function or aggregate, pass NULL pointers for all three function
+** callbacks.
+**
+** ^(If the ninth parameter to sqlite3_create_function_v2() is not NULL,
+** then it is destructor for the application data pointer. 
+** The destructor is invoked when the function is deleted, either by being
+** overloaded or when the database connection closes.)^
+** ^The destructor is also invoked if the call to
+** sqlite3_create_function_v2() fails.
+** ^When the destructor callback of the tenth parameter is invoked, it
+** is passed a single argument which is a copy of the application data 
+** pointer which was the fifth parameter to sqlite3_create_function_v2().
+**
+** ^It is permitted to register multiple implementations of the same
+** functions with the same name but with either differing numbers of
+** arguments or differing preferred text encodings.  ^SQLite will use
+** the implementation that most closely matches the way in which the
+** SQL function is used.  ^A function implementation with a non-negative
+** nArg parameter is a better match than a function implementation with
+** a negative nArg.  ^A function where the preferred text encoding
+** matches the database encoding is a better
+** match than a function where the encoding is different.  
+** ^A function where the encoding difference is between UTF16le and UTF16be
+** is a closer match than a function where the encoding difference is
+** between UTF8 and UTF16.
+**
+** ^Built-in functions may be overloaded by new application-defined functions.
+**
+** ^An application-defined function is permitted to call other
+** SQLite interfaces.  However, such calls must not
+** close the database connection nor finalize or reset the prepared
+** statement in which the function is running.
+*/
+SQLITE_API int sqlite3_create_function(
+  sqlite3 *db,
+  const char *zFunctionName,
+  int nArg,
+  int eTextRep,
+  void *pApp,
+  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
+  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+  void (*xFinal)(sqlite3_context*)
+);
+SQLITE_API int sqlite3_create_function16(
+  sqlite3 *db,
+  const void *zFunctionName,
+  int nArg,
+  int eTextRep,
+  void *pApp,
+  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
+  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+  void (*xFinal)(sqlite3_context*)
+);
+SQLITE_API int sqlite3_create_function_v2(
+  sqlite3 *db,
+  const char *zFunctionName,
+  int nArg,
+  int eTextRep,
+  void *pApp,
+  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
+  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+  void (*xFinal)(sqlite3_context*),
+  void(*xDestroy)(void*)
+);
+
+/*
+** CAPI3REF: Text Encodings
+**
+** These constant define integer codes that represent the various
+** text encodings supported by SQLite.
+*/
+#define SQLITE_UTF8           1    /* IMP: R-37514-35566 */
+#define SQLITE_UTF16LE        2    /* IMP: R-03371-37637 */
+#define SQLITE_UTF16BE        3    /* IMP: R-51971-34154 */
+#define SQLITE_UTF16          4    /* Use native byte order */
+#define SQLITE_ANY            5    /* Deprecated */
+#define SQLITE_UTF16_ALIGNED  8    /* sqlite3_create_collation only */
+
+/*
+** CAPI3REF: Function Flags
+**
+** These constants may be ORed together with the 
+** [SQLITE_UTF8 | preferred text encoding] as the fourth argument
+** to [sqlite3_create_function()], [sqlite3_create_function16()], or
+** [sqlite3_create_function_v2()].
+*/
+#define SQLITE_DETERMINISTIC    0x800
+
+/*
+** CAPI3REF: Deprecated Functions
+** DEPRECATED
+**
+** These functions are [deprecated].  In order to maintain
+** backwards compatibility with older code, these functions continue 
+** to be supported.  However, new applications should avoid
+** the use of these functions.  To encourage programmers to avoid
+** these functions, we will not explain what they do.
+*/
+#ifndef SQLITE_OMIT_DEPRECATED
+SQLITE_API SQLITE_DEPRECATED int sqlite3_aggregate_count(sqlite3_context*);
+SQLITE_API SQLITE_DEPRECATED int sqlite3_expired(sqlite3_stmt*);
+SQLITE_API SQLITE_DEPRECATED int sqlite3_transfer_bindings(sqlite3_stmt*, sqlite3_stmt*);
+SQLITE_API SQLITE_DEPRECATED int sqlite3_global_recover(void);
+SQLITE_API SQLITE_DEPRECATED void sqlite3_thread_cleanup(void);
+SQLITE_API SQLITE_DEPRECATED int sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),
+                      void*,sqlite3_int64);
+#endif
+
+/*
+** CAPI3REF: Obtaining SQL Values
+** METHOD: sqlite3_value
+**
+** The C-language implementation of SQL functions and aggregates uses
+** this set of interface routines to access the parameter values on
+** the function or aggregate.  
+**
+** The xFunc (for scalar functions) or xStep (for aggregates) parameters
+** to [sqlite3_create_function()] and [sqlite3_create_function16()]
+** define callbacks that implement the SQL functions and aggregates.
+** The 3rd parameter to these callbacks is an array of pointers to
+** [protected sqlite3_value] objects.  There is one [sqlite3_value] object for
+** each parameter to the SQL function.  These routines are used to
+** extract values from the [sqlite3_value] objects.
+**
+** These routines work only with [protected sqlite3_value] objects.
+** Any attempt to use these routines on an [unprotected sqlite3_value]
+** object results in undefined behavior.
+**
+** ^These routines work just like the corresponding [column access functions]
+** except that these routines take a single [protected sqlite3_value] object
+** pointer instead of a [sqlite3_stmt*] pointer and an integer column number.
+**
+** ^The sqlite3_value_text16() interface extracts a UTF-16 string
+** in the native byte-order of the host machine.  ^The
+** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces
+** extract UTF-16 strings as big-endian and little-endian respectively.
+**
+** ^(The sqlite3_value_numeric_type() interface attempts to apply
+** numeric affinity to the value.  This means that an attempt is
+** made to convert the value to an integer or floating point.  If
+** such a conversion is possible without loss of information (in other
+** words, if the value is a string that looks like a number)
+** then the conversion is performed.  Otherwise no conversion occurs.
+** The [SQLITE_INTEGER | datatype] after conversion is returned.)^
+**
+** Please pay particular attention to the fact that the pointer returned
+** from [sqlite3_value_blob()], [sqlite3_value_text()], or
+** [sqlite3_value_text16()] can be invalidated by a subsequent call to
+** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],
+** or [sqlite3_value_text16()].
+**
+** These routines must be called from the same thread as
+** the SQL function that supplied the [sqlite3_value*] parameters.
+*/
+SQLITE_API const void *sqlite3_value_blob(sqlite3_value*);
+SQLITE_API int sqlite3_value_bytes(sqlite3_value*);
+SQLITE_API int sqlite3_value_bytes16(sqlite3_value*);
+SQLITE_API double sqlite3_value_double(sqlite3_value*);
+SQLITE_API int sqlite3_value_int(sqlite3_value*);
+SQLITE_API sqlite3_int64 sqlite3_value_int64(sqlite3_value*);
+SQLITE_API const unsigned char *sqlite3_value_text(sqlite3_value*);
+SQLITE_API const void *sqlite3_value_text16(sqlite3_value*);
+SQLITE_API const void *sqlite3_value_text16le(sqlite3_value*);
+SQLITE_API const void *sqlite3_value_text16be(sqlite3_value*);
+SQLITE_API int sqlite3_value_type(sqlite3_value*);
+SQLITE_API int sqlite3_value_numeric_type(sqlite3_value*);
+
+/*
+** CAPI3REF: Finding The Subtype Of SQL Values
+** METHOD: sqlite3_value
+**
+** The sqlite3_value_subtype(V) function returns the subtype for
+** an [application-defined SQL function] argument V.  The subtype
+** information can be used to pass a limited amount of context from
+** one SQL function to another.  Use the [sqlite3_result_subtype()]
+** routine to set the subtype for the return value of an SQL function.
+**
+** SQLite makes no use of subtype itself.  It merely passes the subtype
+** from the result of one [application-defined SQL function] into the
+** input of another.
+*/
+SQLITE_API unsigned int sqlite3_value_subtype(sqlite3_value*);
+
+/*
+** CAPI3REF: Copy And Free SQL Values
+** METHOD: sqlite3_value
+**
+** ^The sqlite3_value_dup(V) interface makes a copy of the [sqlite3_value]
+** object D and returns a pointer to that copy.  ^The [sqlite3_value] returned
+** is a [protected sqlite3_value] object even if the input is not.
+** ^The sqlite3_value_dup(V) interface returns NULL if V is NULL or if a
+** memory allocation fails.
+**
+** ^The sqlite3_value_free(V) interface frees an [sqlite3_value] object
+** previously obtained from [sqlite3_value_dup()].  ^If V is a NULL pointer
+** then sqlite3_value_free(V) is a harmless no-op.
+*/
+SQLITE_API sqlite3_value *sqlite3_value_dup(const sqlite3_value*);
+SQLITE_API void sqlite3_value_free(sqlite3_value*);
+
+/*
+** CAPI3REF: Obtain Aggregate Function Context
+** METHOD: sqlite3_context
+**
+** Implementations of aggregate SQL functions use this
+** routine to allocate memory for storing their state.
+**
+** ^The first time the sqlite3_aggregate_context(C,N) routine is called 
+** for a particular aggregate function, SQLite
+** allocates N of memory, zeroes out that memory, and returns a pointer
+** to the new memory. ^On second and subsequent calls to
+** sqlite3_aggregate_context() for the same aggregate function instance,
+** the same buffer is returned.  Sqlite3_aggregate_context() is normally
+** called once for each invocation of the xStep callback and then one
+** last time when the xFinal callback is invoked.  ^(When no rows match
+** an aggregate query, the xStep() callback of the aggregate function
+** implementation is never called and xFinal() is called exactly once.
+** In those cases, sqlite3_aggregate_context() might be called for the
+** first time from within xFinal().)^
+**
+** ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer 
+** when first called if N is less than or equal to zero or if a memory
+** allocate error occurs.
+**
+** ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is
+** determined by the N parameter on first successful call.  Changing the
+** value of N in subsequent call to sqlite3_aggregate_context() within
+** the same aggregate function instance will not resize the memory
+** allocation.)^  Within the xFinal callback, it is customary to set
+** N=0 in calls to sqlite3_aggregate_context(C,N) so that no 
+** pointless memory allocations occur.
+**
+** ^SQLite automatically frees the memory allocated by 
+** sqlite3_aggregate_context() when the aggregate query concludes.
+**
+** The first parameter must be a copy of the
+** [sqlite3_context | SQL function context] that is the first parameter
+** to the xStep or xFinal callback routine that implements the aggregate
+** function.
+**
+** This routine must be called from the same thread in which
+** the aggregate SQL function is running.
+*/
+SQLITE_API void *sqlite3_aggregate_context(sqlite3_context*, int nBytes);
+
+/*
+** CAPI3REF: User Data For Functions
+** METHOD: sqlite3_context
+**
+** ^The sqlite3_user_data() interface returns a copy of
+** the pointer that was the pUserData parameter (the 5th parameter)
+** of the [sqlite3_create_function()]
+** and [sqlite3_create_function16()] routines that originally
+** registered the application defined function.
+**
+** This routine must be called from the same thread in which
+** the application-defined function is running.
+*/
+SQLITE_API void *sqlite3_user_data(sqlite3_context*);
+
+/*
+** CAPI3REF: Database Connection For Functions
+** METHOD: sqlite3_context
+**
+** ^The sqlite3_context_db_handle() interface returns a copy of
+** the pointer to the [database connection] (the 1st parameter)
+** of the [sqlite3_create_function()]
+** and [sqlite3_create_function16()] routines that originally
+** registered the application defined function.
+*/
+SQLITE_API sqlite3 *sqlite3_context_db_handle(sqlite3_context*);
+
+/*
+** CAPI3REF: Function Auxiliary Data
+** METHOD: sqlite3_context
+**
+** These functions may be used by (non-aggregate) SQL functions to
+** associate metadata with argument values. If the same value is passed to
+** multiple invocations of the same SQL function during query execution, under
+** some circumstances the associated metadata may be preserved.  An example
+** of where this might be useful is in a regular-expression matching
+** function. The compiled version of the regular expression can be stored as
+** metadata associated with the pattern string.  
+** Then as long as the pattern string remains the same,
+** the compiled regular expression can be reused on multiple
+** invocations of the same function.
+**
+** ^The sqlite3_get_auxdata() interface returns a pointer to the metadata
+** associated by the sqlite3_set_auxdata() function with the Nth argument
+** value to the application-defined function. ^If there is no metadata
+** associated with the function argument, this sqlite3_get_auxdata() interface
+** returns a NULL pointer.
+**
+** ^The sqlite3_set_auxdata(C,N,P,X) interface saves P as metadata for the N-th
+** argument of the application-defined function.  ^Subsequent
+** calls to sqlite3_get_auxdata(C,N) return P from the most recent
+** sqlite3_set_auxdata(C,N,P,X) call if the metadata is still valid or
+** NULL if the metadata has been discarded.
+** ^After each call to sqlite3_set_auxdata(C,N,P,X) where X is not NULL,
+** SQLite will invoke the destructor function X with parameter P exactly
+** once, when the metadata is discarded.
+** SQLite is free to discard the metadata at any time, including: <ul>
+** <li> ^(when the corresponding function parameter changes)^, or
+** <li> ^(when [sqlite3_reset()] or [sqlite3_finalize()] is called for the
+**      SQL statement)^, or
+** <li> ^(when sqlite3_set_auxdata() is invoked again on the same
+**       parameter)^, or
+** <li> ^(during the original sqlite3_set_auxdata() call when a memory 
+**      allocation error occurs.)^ </ul>
+**
+** Note the last bullet in particular.  The destructor X in 
+** sqlite3_set_auxdata(C,N,P,X) might be called immediately, before the
+** sqlite3_set_auxdata() interface even returns.  Hence sqlite3_set_auxdata()
+** should be called near the end of the function implementation and the
+** function implementation should not make any use of P after
+** sqlite3_set_auxdata() has been called.
+**
+** ^(In practice, metadata is preserved between function calls for
+** function parameters that are compile-time constants, including literal
+** values and [parameters] and expressions composed from the same.)^
+**
+** These routines must be called from the same thread in which
+** the SQL function is running.
+*/
+SQLITE_API void *sqlite3_get_auxdata(sqlite3_context*, int N);
+SQLITE_API void sqlite3_set_auxdata(sqlite3_context*, int N, void*, void (*)(void*));
+
+
+/*
+** CAPI3REF: Constants Defining Special Destructor Behavior
+**
+** These are special values for the destructor that is passed in as the
+** final argument to routines like [sqlite3_result_blob()].  ^If the destructor
+** argument is SQLITE_STATIC, it means that the content pointer is constant
+** and will never change.  It does not need to be destroyed.  ^The
+** SQLITE_TRANSIENT value means that the content will likely change in
+** the near future and that SQLite should make its own private copy of
+** the content before returning.
+**
+** The typedef is necessary to work around problems in certain
+** C++ compilers.
+*/
+typedef void (*sqlite3_destructor_type)(void*);
+#define SQLITE_STATIC      ((sqlite3_destructor_type)0)
+#define SQLITE_TRANSIENT   ((sqlite3_destructor_type)-1)
+
+/*
+** CAPI3REF: Setting The Result Of An SQL Function
+** METHOD: sqlite3_context
+**
+** These routines are used by the xFunc or xFinal callbacks that
+** implement SQL functions and aggregates.  See
+** [sqlite3_create_function()] and [sqlite3_create_function16()]
+** for additional information.
+**
+** These functions work very much like the [parameter binding] family of
+** functions used to bind values to host parameters in prepared statements.
+** Refer to the [SQL parameter] documentation for additional information.
+**
+** ^The sqlite3_result_blob() interface sets the result from
+** an application-defined function to be the BLOB whose content is pointed
+** to by the second parameter and which is N bytes long where N is the
+** third parameter.
+**
+** ^The sqlite3_result_zeroblob(C,N) and sqlite3_result_zeroblob64(C,N)
+** interfaces set the result of the application-defined function to be
+** a BLOB containing all zero bytes and N bytes in size.
+**
+** ^The sqlite3_result_double() interface sets the result from
+** an application-defined function to be a floating point value specified
+** by its 2nd argument.
+**
+** ^The sqlite3_result_error() and sqlite3_result_error16() functions
+** cause the implemented SQL function to throw an exception.
+** ^SQLite uses the string pointed to by the
+** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()
+** as the text of an error message.  ^SQLite interprets the error
+** message string from sqlite3_result_error() as UTF-8. ^SQLite
+** interprets the string from sqlite3_result_error16() as UTF-16 in native
+** byte order.  ^If the third parameter to sqlite3_result_error()
+** or sqlite3_result_error16() is negative then SQLite takes as the error
+** message all text up through the first zero character.
+** ^If the third parameter to sqlite3_result_error() or
+** sqlite3_result_error16() is non-negative then SQLite takes that many
+** bytes (not characters) from the 2nd parameter as the error message.
+** ^The sqlite3_result_error() and sqlite3_result_error16()
+** routines make a private copy of the error message text before
+** they return.  Hence, the calling function can deallocate or
+** modify the text after they return without harm.
+** ^The sqlite3_result_error_code() function changes the error code
+** returned by SQLite as a result of an error in a function.  ^By default,
+** the error code is SQLITE_ERROR.  ^A subsequent call to sqlite3_result_error()
+** or sqlite3_result_error16() resets the error code to SQLITE_ERROR.
+**
+** ^The sqlite3_result_error_toobig() interface causes SQLite to throw an
+** error indicating that a string or BLOB is too long to represent.
+**
+** ^The sqlite3_result_error_nomem() interface causes SQLite to throw an
+** error indicating that a memory allocation failed.
+**
+** ^The sqlite3_result_int() interface sets the return value
+** of the application-defined function to be the 32-bit signed integer
+** value given in the 2nd argument.
+** ^The sqlite3_result_int64() interface sets the return value
+** of the application-defined function to be the 64-bit signed integer
+** value given in the 2nd argument.
+**
+** ^The sqlite3_result_null() interface sets the return value
+** of the application-defined function to be NULL.
+**
+** ^The sqlite3_result_text(), sqlite3_result_text16(),
+** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces
+** set the return value of the application-defined function to be
+** a text string which is represented as UTF-8, UTF-16 native byte order,
+** UTF-16 little endian, or UTF-16 big endian, respectively.
+** ^The sqlite3_result_text64() interface sets the return value of an
+** application-defined function to be a text string in an encoding
+** specified by the fifth (and last) parameter, which must be one
+** of [SQLITE_UTF8], [SQLITE_UTF16], [SQLITE_UTF16BE], or [SQLITE_UTF16LE].
+** ^SQLite takes the text result from the application from
+** the 2nd parameter of the sqlite3_result_text* interfaces.
+** ^If the 3rd parameter to the sqlite3_result_text* interfaces
+** is negative, then SQLite takes result text from the 2nd parameter
+** through the first zero character.
+** ^If the 3rd parameter to the sqlite3_result_text* interfaces
+** is non-negative, then as many bytes (not characters) of the text
+** pointed to by the 2nd parameter are taken as the application-defined
+** function result.  If the 3rd parameter is non-negative, then it
+** must be the byte offset into the string where the NUL terminator would
+** appear if the string where NUL terminated.  If any NUL characters occur
+** in the string at a byte offset that is less than the value of the 3rd
+** parameter, then the resulting string will contain embedded NULs and the
+** result of expressions operating on strings with embedded NULs is undefined.
+** ^If the 4th parameter to the sqlite3_result_text* interfaces
+** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
+** function as the destructor on the text or BLOB result when it has
+** finished using that result.
+** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
+** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
+** assumes that the text or BLOB result is in constant space and does not
+** copy the content of the parameter nor call a destructor on the content
+** when it has finished using that result.
+** ^If the 4th parameter to the sqlite3_result_text* interfaces
+** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT
+** then SQLite makes a copy of the result into space obtained from
+** from [sqlite3_malloc()] before it returns.
+**
+** ^The sqlite3_result_value() interface sets the result of
+** the application-defined function to be a copy of the
+** [unprotected sqlite3_value] object specified by the 2nd parameter.  ^The
+** sqlite3_result_value() interface makes a copy of the [sqlite3_value]
+** so that the [sqlite3_value] specified in the parameter may change or
+** be deallocated after sqlite3_result_value() returns without harm.
+** ^A [protected sqlite3_value] object may always be used where an
+** [unprotected sqlite3_value] object is required, so either
+** kind of [sqlite3_value] object can be used with this interface.
+**
+** If these routines are called from within the different thread
+** than the one containing the application-defined function that received
+** the [sqlite3_context] pointer, the results are undefined.
+*/
+SQLITE_API void sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*));
+SQLITE_API void sqlite3_result_blob64(sqlite3_context*,const void*,
+                           sqlite3_uint64,void(*)(void*));
+SQLITE_API void sqlite3_result_double(sqlite3_context*, double);
+SQLITE_API void sqlite3_result_error(sqlite3_context*, const char*, int);
+SQLITE_API void sqlite3_result_error16(sqlite3_context*, const void*, int);
+SQLITE_API void sqlite3_result_error_toobig(sqlite3_context*);
+SQLITE_API void sqlite3_result_error_nomem(sqlite3_context*);
+SQLITE_API void sqlite3_result_error_code(sqlite3_context*, int);
+SQLITE_API void sqlite3_result_int(sqlite3_context*, int);
+SQLITE_API void sqlite3_result_int64(sqlite3_context*, sqlite3_int64);
+SQLITE_API void sqlite3_result_null(sqlite3_context*);
+SQLITE_API void sqlite3_result_text(sqlite3_context*, const char*, int, void(*)(void*));
+SQLITE_API void sqlite3_result_text64(sqlite3_context*, const char*,sqlite3_uint64,
+                           void(*)(void*), unsigned char encoding);
+SQLITE_API void sqlite3_result_text16(sqlite3_context*, const void*, int, void(*)(void*));
+SQLITE_API void sqlite3_result_text16le(sqlite3_context*, const void*, int,void(*)(void*));
+SQLITE_API void sqlite3_result_text16be(sqlite3_context*, const void*, int,void(*)(void*));
+SQLITE_API void sqlite3_result_value(sqlite3_context*, sqlite3_value*);
+SQLITE_API void sqlite3_result_zeroblob(sqlite3_context*, int n);
+SQLITE_API int sqlite3_result_zeroblob64(sqlite3_context*, sqlite3_uint64 n);
+
+
+/*
+** CAPI3REF: Setting The Subtype Of An SQL Function
+** METHOD: sqlite3_context
+**
+** The sqlite3_result_subtype(C,T) function causes the subtype of
+** the result from the [application-defined SQL function] with 
+** [sqlite3_context] C to be the value T.  Only the lower 8 bits 
+** of the subtype T are preserved in current versions of SQLite;
+** higher order bits are discarded.
+** The number of subtype bytes preserved by SQLite might increase
+** in future releases of SQLite.
+*/
+SQLITE_API void sqlite3_result_subtype(sqlite3_context*,unsigned int);
+
+/*
+** CAPI3REF: Define New Collating Sequences
+** METHOD: sqlite3
+**
+** ^These functions add, remove, or modify a [collation] associated
+** with the [database connection] specified as the first argument.
+**
+** ^The name of the collation is a UTF-8 string
+** for sqlite3_create_collation() and sqlite3_create_collation_v2()
+** and a UTF-16 string in native byte order for sqlite3_create_collation16().
+** ^Collation names that compare equal according to [sqlite3_strnicmp()] are
+** considered to be the same name.
+**
+** ^(The third argument (eTextRep) must be one of the constants:
+** <ul>
+** <li> [SQLITE_UTF8],
+** <li> [SQLITE_UTF16LE],
+** <li> [SQLITE_UTF16BE],
+** <li> [SQLITE_UTF16], or
+** <li> [SQLITE_UTF16_ALIGNED].
+** </ul>)^
+** ^The eTextRep argument determines the encoding of strings passed
+** to the collating function callback, xCallback.
+** ^The [SQLITE_UTF16] and [SQLITE_UTF16_ALIGNED] values for eTextRep
+** force strings to be UTF16 with native byte order.
+** ^The [SQLITE_UTF16_ALIGNED] value for eTextRep forces strings to begin
+** on an even byte address.
+**
+** ^The fourth argument, pArg, is an application data pointer that is passed
+** through as the first argument to the collating function callback.
+**
+** ^The fifth argument, xCallback, is a pointer to the collating function.
+** ^Multiple collating functions can be registered using the same name but
+** with different eTextRep parameters and SQLite will use whichever
+** function requires the least amount of data transformation.
+** ^If the xCallback argument is NULL then the collating function is
+** deleted.  ^When all collating functions having the same name are deleted,
+** that collation is no longer usable.
+**
+** ^The collating function callback is invoked with a copy of the pArg 
+** application data pointer and with two strings in the encoding specified
+** by the eTextRep argument.  The collating function must return an
+** integer that is negative, zero, or positive
+** if the first string is less than, equal to, or greater than the second,
+** respectively.  A collating function must always return the same answer
+** given the same inputs.  If two or more collating functions are registered
+** to the same collation name (using different eTextRep values) then all
+** must give an equivalent answer when invoked with equivalent strings.
+** The collating function must obey the following properties for all
+** strings A, B, and C:
+**
+** <ol>
+** <li> If A==B then B==A.
+** <li> If A==B and B==C then A==C.
+** <li> If A&lt;B THEN B&gt;A.
+** <li> If A&lt;B and B&lt;C then A&lt;C.
+** </ol>
+**
+** If a collating function fails any of the above constraints and that
+** collating function is  registered and used, then the behavior of SQLite
+** is undefined.
+**
+** ^The sqlite3_create_collation_v2() works like sqlite3_create_collation()
+** with the addition that the xDestroy callback is invoked on pArg when
+** the collating function is deleted.
+** ^Collating functions are deleted when they are overridden by later
+** calls to the collation creation functions or when the
+** [database connection] is closed using [sqlite3_close()].
+**
+** ^The xDestroy callback is <u>not</u> called if the 
+** sqlite3_create_collation_v2() function fails.  Applications that invoke
+** sqlite3_create_collation_v2() with a non-NULL xDestroy argument should 
+** check the return code and dispose of the application data pointer
+** themselves rather than expecting SQLite to deal with it for them.
+** This is different from every other SQLite interface.  The inconsistency 
+** is unfortunate but cannot be changed without breaking backwards 
+** compatibility.
+**
+** See also:  [sqlite3_collation_needed()] and [sqlite3_collation_needed16()].
+*/
+SQLITE_API int sqlite3_create_collation(
+  sqlite3*, 
+  const char *zName, 
+  int eTextRep, 
+  void *pArg,
+  int(*xCompare)(void*,int,const void*,int,const void*)
+);
+SQLITE_API int sqlite3_create_collation_v2(
+  sqlite3*, 
+  const char *zName, 
+  int eTextRep, 
+  void *pArg,
+  int(*xCompare)(void*,int,const void*,int,const void*),
+  void(*xDestroy)(void*)
+);
+SQLITE_API int sqlite3_create_collation16(
+  sqlite3*, 
+  const void *zName,
+  int eTextRep, 
+  void *pArg,
+  int(*xCompare)(void*,int,const void*,int,const void*)
+);
+
+/*
+** CAPI3REF: Collation Needed Callbacks
+** METHOD: sqlite3
+**
+** ^To avoid having to register all collation sequences before a database
+** can be used, a single callback function may be registered with the
+** [database connection] to be invoked whenever an undefined collation
+** sequence is required.
+**
+** ^If the function is registered using the sqlite3_collation_needed() API,
+** then it is passed the names of undefined collation sequences as strings
+** encoded in UTF-8. ^If sqlite3_collation_needed16() is used,
+** the names are passed as UTF-16 in machine native byte order.
+** ^A call to either function replaces the existing collation-needed callback.
+**
+** ^(When the callback is invoked, the first argument passed is a copy
+** of the second argument to sqlite3_collation_needed() or
+** sqlite3_collation_needed16().  The second argument is the database
+** connection.  The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE],
+** or [SQLITE_UTF16LE], indicating the most desirable form of the collation
+** sequence function required.  The fourth parameter is the name of the
+** required collation sequence.)^
+**
+** The callback function should register the desired collation using
+** [sqlite3_create_collation()], [sqlite3_create_collation16()], or
+** [sqlite3_create_collation_v2()].
+*/
+SQLITE_API int sqlite3_collation_needed(
+  sqlite3*, 
+  void*, 
+  void(*)(void*,sqlite3*,int eTextRep,const char*)
+);
+SQLITE_API int sqlite3_collation_needed16(
+  sqlite3*, 
+  void*,
+  void(*)(void*,sqlite3*,int eTextRep,const void*)
+);
+
+#ifdef SQLITE_HAS_CODEC
+/*
+** Specify the key for an encrypted database.  This routine should be
+** called right after sqlite3_open().
+**
+** The code to implement this API is not available in the public release
+** of SQLite.
+*/
+SQLITE_API int sqlite3_key(
+  sqlite3 *db,                   /* Database to be rekeyed */
+  const void *pKey, int nKey     /* The key */
+);
+SQLITE_API int sqlite3_key_v2(
+  sqlite3 *db,                   /* Database to be rekeyed */
+  const char *zDbName,           /* Name of the database */
+  const void *pKey, int nKey     /* The key */
+);
+
+/*
+** Change the key on an open database.  If the current database is not
+** encrypted, this routine will encrypt it.  If pNew==0 or nNew==0, the
+** database is decrypted.
+**
+** The code to implement this API is not available in the public release
+** of SQLite.
+*/
+SQLITE_API int sqlite3_rekey(
+  sqlite3 *db,                   /* Database to be rekeyed */
+  const void *pKey, int nKey     /* The new key */
+);
+SQLITE_API int sqlite3_rekey_v2(
+  sqlite3 *db,                   /* Database to be rekeyed */
+  const char *zDbName,           /* Name of the database */
+  const void *pKey, int nKey     /* The new key */
+);
+
+/*
+** Specify the activation key for a SEE database.  Unless 
+** activated, none of the SEE routines will work.
+*/
+SQLITE_API void sqlite3_activate_see(
+  const char *zPassPhrase        /* Activation phrase */
+);
+#endif
+
+#ifdef SQLITE_ENABLE_CEROD
+/*
+** Specify the activation key for a CEROD database.  Unless 
+** activated, none of the CEROD routines will work.
+*/
+SQLITE_API void sqlite3_activate_cerod(
+  const char *zPassPhrase        /* Activation phrase */
+);
+#endif
+
+/*
+** CAPI3REF: Suspend Execution For A Short Time
+**
+** The sqlite3_sleep() function causes the current thread to suspend execution
+** for at least a number of milliseconds specified in its parameter.
+**
+** If the operating system does not support sleep requests with
+** millisecond time resolution, then the time will be rounded up to
+** the nearest second. The number of milliseconds of sleep actually
+** requested from the operating system is returned.
+**
+** ^SQLite implements this interface by calling the xSleep()
+** method of the default [sqlite3_vfs] object.  If the xSleep() method
+** of the default VFS is not implemented correctly, or not implemented at
+** all, then the behavior of sqlite3_sleep() may deviate from the description
+** in the previous paragraphs.
+*/
+SQLITE_API int sqlite3_sleep(int);
+
+/*
+** CAPI3REF: Name Of The Folder Holding Temporary Files
+**
+** ^(If this global variable is made to point to a string which is
+** the name of a folder (a.k.a. directory), then all temporary files
+** created by SQLite when using a built-in [sqlite3_vfs | VFS]
+** will be placed in that directory.)^  ^If this variable
+** is a NULL pointer, then SQLite performs a search for an appropriate
+** temporary file directory.
+**
+** Applications are strongly discouraged from using this global variable.
+** It is required to set a temporary folder on Windows Runtime (WinRT).
+** But for all other platforms, it is highly recommended that applications
+** neither read nor write this variable.  This global variable is a relic
+** that exists for backwards compatibility of legacy applications and should
+** be avoided in new projects.
+**
+** It is not safe to read or modify this variable in more than one
+** thread at a time.  It is not safe to read or modify this variable
+** if a [database connection] is being used at the same time in a separate
+** thread.
+** It is intended that this variable be set once
+** as part of process initialization and before any SQLite interface
+** routines have been called and that this variable remain unchanged
+** thereafter.
+**
+** ^The [temp_store_directory pragma] may modify this variable and cause
+** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
+** the [temp_store_directory pragma] always assumes that any string
+** that this variable points to is held in memory obtained from 
+** [sqlite3_malloc] and the pragma may attempt to free that memory
+** using [sqlite3_free].
+** Hence, if this variable is modified directly, either it should be
+** made NULL or made to point to memory obtained from [sqlite3_malloc]
+** or else the use of the [temp_store_directory pragma] should be avoided.
+** Except when requested by the [temp_store_directory pragma], SQLite
+** does not free the memory that sqlite3_temp_directory points to.  If
+** the application wants that memory to be freed, it must do
+** so itself, taking care to only do so after all [database connection]
+** objects have been destroyed.
+**
+** <b>Note to Windows Runtime users:</b>  The temporary directory must be set
+** prior to calling [sqlite3_open] or [sqlite3_open_v2].  Otherwise, various
+** features that require the use of temporary files may fail.  Here is an
+** example of how to do this using C++ with the Windows Runtime:
+**
+** <blockquote><pre>
+** LPCWSTR zPath = Windows::Storage::ApplicationData::Current->
+** &nbsp;     TemporaryFolder->Path->Data();
+** char zPathBuf&#91;MAX_PATH + 1&#93;;
+** memset(zPathBuf, 0, sizeof(zPathBuf));
+** WideCharToMultiByte(CP_UTF8, 0, zPath, -1, zPathBuf, sizeof(zPathBuf),
+** &nbsp;     NULL, NULL);
+** sqlite3_temp_directory = sqlite3_mprintf("%s", zPathBuf);
+** </pre></blockquote>
+*/
+SQLITE_API SQLITE_EXTERN char *sqlite3_temp_directory;
+
+/*
+** CAPI3REF: Name Of The Folder Holding Database Files
+**
+** ^(If this global variable is made to point to a string which is
+** the name of a folder (a.k.a. directory), then all database files
+** specified with a relative pathname and created or accessed by
+** SQLite when using a built-in windows [sqlite3_vfs | VFS] will be assumed
+** to be relative to that directory.)^ ^If this variable is a NULL
+** pointer, then SQLite assumes that all database files specified
+** with a relative pathname are relative to the current directory
+** for the process.  Only the windows VFS makes use of this global
+** variable; it is ignored by the unix VFS.
+**
+** Changing the value of this variable while a database connection is
+** open can result in a corrupt database.
+**
+** It is not safe to read or modify this variable in more than one
+** thread at a time.  It is not safe to read or modify this variable
+** if a [database connection] is being used at the same time in a separate
+** thread.
+** It is intended that this variable be set once
+** as part of process initialization and before any SQLite interface
+** routines have been called and that this variable remain unchanged
+** thereafter.
+**
+** ^The [data_store_directory pragma] may modify this variable and cause
+** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
+** the [data_store_directory pragma] always assumes that any string
+** that this variable points to is held in memory obtained from 
+** [sqlite3_malloc] and the pragma may attempt to free that memory
+** using [sqlite3_free].
+** Hence, if this variable is modified directly, either it should be
+** made NULL or made to point to memory obtained from [sqlite3_malloc]
+** or else the use of the [data_store_directory pragma] should be avoided.
+*/
+SQLITE_API SQLITE_EXTERN char *sqlite3_data_directory;
+
+/*
+** CAPI3REF: Test For Auto-Commit Mode
+** KEYWORDS: {autocommit mode}
+** METHOD: sqlite3
+**
+** ^The sqlite3_get_autocommit() interface returns non-zero or
+** zero if the given database connection is or is not in autocommit mode,
+** respectively.  ^Autocommit mode is on by default.
+** ^Autocommit mode is disabled by a [BEGIN] statement.
+** ^Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK].
+**
+** If certain kinds of errors occur on a statement within a multi-statement
+** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR],
+** [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the
+** transaction might be rolled back automatically.  The only way to
+** find out whether SQLite automatically rolled back the transaction after
+** an error is to use this function.
+**
+** If another thread changes the autocommit status of the database
+** connection while this routine is running, then the return value
+** is undefined.
+*/
+SQLITE_API int sqlite3_get_autocommit(sqlite3*);
+
+/*
+** CAPI3REF: Find The Database Handle Of A Prepared Statement
+** METHOD: sqlite3_stmt
+**
+** ^The sqlite3_db_handle interface returns the [database connection] handle
+** to which a [prepared statement] belongs.  ^The [database connection]
+** returned by sqlite3_db_handle is the same [database connection]
+** that was the first argument
+** to the [sqlite3_prepare_v2()] call (or its variants) that was used to
+** create the statement in the first place.
+*/
+SQLITE_API sqlite3 *sqlite3_db_handle(sqlite3_stmt*);
+
+/*
+** CAPI3REF: Return The Filename For A Database Connection
+** METHOD: sqlite3
+**
+** ^The sqlite3_db_filename(D,N) interface returns a pointer to a filename
+** associated with database N of connection D.  ^The main database file
+** has the name "main".  If there is no attached database N on the database
+** connection D, or if database N is a temporary or in-memory database, then
+** a NULL pointer is returned.
+**
+** ^The filename returned by this function is the output of the
+** xFullPathname method of the [VFS].  ^In other words, the filename
+** will be an absolute pathname, even if the filename used
+** to open the database originally was a URI or relative pathname.
+*/
+SQLITE_API const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName);
+
+/*
+** CAPI3REF: Determine if a database is read-only
+** METHOD: sqlite3
+**
+** ^The sqlite3_db_readonly(D,N) interface returns 1 if the database N
+** of connection D is read-only, 0 if it is read/write, or -1 if N is not
+** the name of a database on connection D.
+*/
+SQLITE_API int sqlite3_db_readonly(sqlite3 *db, const char *zDbName);
+
+/*
+** CAPI3REF: Find the next prepared statement
+** METHOD: sqlite3
+**
+** ^This interface returns a pointer to the next [prepared statement] after
+** pStmt associated with the [database connection] pDb.  ^If pStmt is NULL
+** then this interface returns a pointer to the first prepared statement
+** associated with the database connection pDb.  ^If no prepared statement
+** satisfies the conditions of this routine, it returns NULL.
+**
+** The [database connection] pointer D in a call to
+** [sqlite3_next_stmt(D,S)] must refer to an open database
+** connection and in particular must not be a NULL pointer.
+*/
+SQLITE_API sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Commit And Rollback Notification Callbacks
+** METHOD: sqlite3
+**
+** ^The sqlite3_commit_hook() interface registers a callback
+** function to be invoked whenever a transaction is [COMMIT | committed].
+** ^Any callback set by a previous call to sqlite3_commit_hook()
+** for the same database connection is overridden.
+** ^The sqlite3_rollback_hook() interface registers a callback
+** function to be invoked whenever a transaction is [ROLLBACK | rolled back].
+** ^Any callback set by a previous call to sqlite3_rollback_hook()
+** for the same database connection is overridden.
+** ^The pArg argument is passed through to the callback.
+** ^If the callback on a commit hook function returns non-zero,
+** then the commit is converted into a rollback.
+**
+** ^The sqlite3_commit_hook(D,C,P) and sqlite3_rollback_hook(D,C,P) functions
+** return the P argument from the previous call of the same function
+** on the same [database connection] D, or NULL for
+** the first call for each function on D.
+**
+** The commit and rollback hook callbacks are not reentrant.
+** The callback implementation must not do anything that will modify
+** the database connection that invoked the callback.  Any actions
+** to modify the database connection must be deferred until after the
+** completion of the [sqlite3_step()] call that triggered the commit
+** or rollback hook in the first place.
+** Note that running any other SQL statements, including SELECT statements,
+** or merely calling [sqlite3_prepare_v2()] and [sqlite3_step()] will modify
+** the database connections for the meaning of "modify" in this paragraph.
+**
+** ^Registering a NULL function disables the callback.
+**
+** ^When the commit hook callback routine returns zero, the [COMMIT]
+** operation is allowed to continue normally.  ^If the commit hook
+** returns non-zero, then the [COMMIT] is converted into a [ROLLBACK].
+** ^The rollback hook is invoked on a rollback that results from a commit
+** hook returning non-zero, just as it would be with any other rollback.
+**
+** ^For the purposes of this API, a transaction is said to have been
+** rolled back if an explicit "ROLLBACK" statement is executed, or
+** an error or constraint causes an implicit rollback to occur.
+** ^The rollback callback is not invoked if a transaction is
+** automatically rolled back because the database connection is closed.
+**
+** See also the [sqlite3_update_hook()] interface.
+*/
+SQLITE_API void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
+SQLITE_API void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
+
+/*
+** CAPI3REF: Data Change Notification Callbacks
+** METHOD: sqlite3
+**
+** ^The sqlite3_update_hook() interface registers a callback function
+** with the [database connection] identified by the first argument
+** to be invoked whenever a row is updated, inserted or deleted in
+** a [rowid table].
+** ^Any callback set by a previous call to this function
+** for the same database connection is overridden.
+**
+** ^The second argument is a pointer to the function to invoke when a
+** row is updated, inserted or deleted in a rowid table.
+** ^The first argument to the callback is a copy of the third argument
+** to sqlite3_update_hook().
+** ^The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE],
+** or [SQLITE_UPDATE], depending on the operation that caused the callback
+** to be invoked.
+** ^The third and fourth arguments to the callback contain pointers to the
+** database and table name containing the affected row.
+** ^The final callback parameter is the [rowid] of the row.
+** ^In the case of an update, this is the [rowid] after the update takes place.
+**
+** ^(The update hook is not invoked when internal system tables are
+** modified (i.e. sqlite_master and sqlite_sequence).)^
+** ^The update hook is not invoked when [WITHOUT ROWID] tables are modified.
+**
+** ^In the current implementation, the update hook
+** is not invoked when duplication rows are deleted because of an
+** [ON CONFLICT | ON CONFLICT REPLACE] clause.  ^Nor is the update hook
+** invoked when rows are deleted using the [truncate optimization].
+** The exceptions defined in this paragraph might change in a future
+** release of SQLite.
+**
+** The update hook implementation must not do anything that will modify
+** the database connection that invoked the update hook.  Any actions
+** to modify the database connection must be deferred until after the
+** completion of the [sqlite3_step()] call that triggered the update hook.
+** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
+** database connections for the meaning of "modify" in this paragraph.
+**
+** ^The sqlite3_update_hook(D,C,P) function
+** returns the P argument from the previous call
+** on the same [database connection] D, or NULL for
+** the first call on D.
+**
+** See also the [sqlite3_commit_hook()], [sqlite3_rollback_hook()],
+** and [sqlite3_preupdate_hook()] interfaces.
+*/
+SQLITE_API void *sqlite3_update_hook(
+  sqlite3*, 
+  void(*)(void *,int ,char const *,char const *,sqlite3_int64),
+  void*
+);
+
+/*
+** CAPI3REF: Enable Or Disable Shared Pager Cache
+**
+** ^(This routine enables or disables the sharing of the database cache
+** and schema data structures between [database connection | connections]
+** to the same database. Sharing is enabled if the argument is true
+** and disabled if the argument is false.)^
+**
+** ^Cache sharing is enabled and disabled for an entire process.
+** This is a change as of SQLite [version 3.5.0] ([dateof:3.5.0]). 
+** In prior versions of SQLite,
+** sharing was enabled or disabled for each thread separately.
+**
+** ^(The cache sharing mode set by this interface effects all subsequent
+** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()].
+** Existing database connections continue use the sharing mode
+** that was in effect at the time they were opened.)^
+**
+** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled
+** successfully.  An [error code] is returned otherwise.)^
+**
+** ^Shared cache is disabled by default. But this might change in
+** future releases of SQLite.  Applications that care about shared
+** cache setting should set it explicitly.
+**
+** Note: This method is disabled on MacOS X 10.7 and iOS version 5.0
+** and will always return SQLITE_MISUSE. On those systems, 
+** shared cache mode should be enabled per-database connection via 
+** [sqlite3_open_v2()] with [SQLITE_OPEN_SHAREDCACHE].
+**
+** This interface is threadsafe on processors where writing a
+** 32-bit integer is atomic.
+**
+** See Also:  [SQLite Shared-Cache Mode]
+*/
+SQLITE_API int sqlite3_enable_shared_cache(int);
+
+/*
+** CAPI3REF: Attempt To Free Heap Memory
+**
+** ^The sqlite3_release_memory() interface attempts to free N bytes
+** of heap memory by deallocating non-essential memory allocations
+** held by the database library.   Memory used to cache database
+** pages to improve performance is an example of non-essential memory.
+** ^sqlite3_release_memory() returns the number of bytes actually freed,
+** which might be more or less than the amount requested.
+** ^The sqlite3_release_memory() routine is a no-op returning zero
+** if SQLite is not compiled with [SQLITE_ENABLE_MEMORY_MANAGEMENT].
+**
+** See also: [sqlite3_db_release_memory()]
+*/
+SQLITE_API int sqlite3_release_memory(int);
+
+/*
+** CAPI3REF: Free Memory Used By A Database Connection
+** METHOD: sqlite3
+**
+** ^The sqlite3_db_release_memory(D) interface attempts to free as much heap
+** memory as possible from database connection D. Unlike the
+** [sqlite3_release_memory()] interface, this interface is in effect even
+** when the [SQLITE_ENABLE_MEMORY_MANAGEMENT] compile-time option is
+** omitted.
+**
+** See also: [sqlite3_release_memory()]
+*/
+SQLITE_API int sqlite3_db_release_memory(sqlite3*);
+
+/*
+** CAPI3REF: Impose A Limit On Heap Size
+**
+** ^The sqlite3_soft_heap_limit64() interface sets and/or queries the
+** soft limit on the amount of heap memory that may be allocated by SQLite.
+** ^SQLite strives to keep heap memory utilization below the soft heap
+** limit by reducing the number of pages held in the page cache
+** as heap memory usages approaches the limit.
+** ^The soft heap limit is "soft" because even though SQLite strives to stay
+** below the limit, it will exceed the limit rather than generate
+** an [SQLITE_NOMEM] error.  In other words, the soft heap limit 
+** is advisory only.
+**
+** ^The return value from sqlite3_soft_heap_limit64() is the size of
+** the soft heap limit prior to the call, or negative in the case of an
+** error.  ^If the argument N is negative
+** then no change is made to the soft heap limit.  Hence, the current
+** size of the soft heap limit can be determined by invoking
+** sqlite3_soft_heap_limit64() with a negative argument.
+**
+** ^If the argument N is zero then the soft heap limit is disabled.
+**
+** ^(The soft heap limit is not enforced in the current implementation
+** if one or more of following conditions are true:
+**
+** <ul>
+** <li> The soft heap limit is set to zero.
+** <li> Memory accounting is disabled using a combination of the
+**      [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and
+**      the [SQLITE_DEFAULT_MEMSTATUS] compile-time option.
+** <li> An alternative page cache implementation is specified using
+**      [sqlite3_config]([SQLITE_CONFIG_PCACHE2],...).
+** <li> The page cache allocates from its own memory pool supplied
+**      by [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],...) rather than
+**      from the heap.
+** </ul>)^
+**
+** Beginning with SQLite [version 3.7.3] ([dateof:3.7.3]), 
+** the soft heap limit is enforced
+** regardless of whether or not the [SQLITE_ENABLE_MEMORY_MANAGEMENT]
+** compile-time option is invoked.  With [SQLITE_ENABLE_MEMORY_MANAGEMENT],
+** the soft heap limit is enforced on every memory allocation.  Without
+** [SQLITE_ENABLE_MEMORY_MANAGEMENT], the soft heap limit is only enforced
+** when memory is allocated by the page cache.  Testing suggests that because
+** the page cache is the predominate memory user in SQLite, most
+** applications will achieve adequate soft heap limit enforcement without
+** the use of [SQLITE_ENABLE_MEMORY_MANAGEMENT].
+**
+** The circumstances under which SQLite will enforce the soft heap limit may
+** changes in future releases of SQLite.
+*/
+SQLITE_API sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 N);
+
+/*
+** CAPI3REF: Deprecated Soft Heap Limit Interface
+** DEPRECATED
+**
+** This is a deprecated version of the [sqlite3_soft_heap_limit64()]
+** interface.  This routine is provided for historical compatibility
+** only.  All new applications should use the
+** [sqlite3_soft_heap_limit64()] interface rather than this one.
+*/
+SQLITE_API SQLITE_DEPRECATED void sqlite3_soft_heap_limit(int N);
+
+
+/*
+** CAPI3REF: Extract Metadata About A Column Of A Table
+** METHOD: sqlite3
+**
+** ^(The sqlite3_table_column_metadata(X,D,T,C,....) routine returns
+** information about column C of table T in database D
+** on [database connection] X.)^  ^The sqlite3_table_column_metadata()
+** interface returns SQLITE_OK and fills in the non-NULL pointers in
+** the final five arguments with appropriate values if the specified
+** column exists.  ^The sqlite3_table_column_metadata() interface returns
+** SQLITE_ERROR and if the specified column does not exist.
+** ^If the column-name parameter to sqlite3_table_column_metadata() is a
+** NULL pointer, then this routine simply checks for the existence of the
+** table and returns SQLITE_OK if the table exists and SQLITE_ERROR if it
+** does not.
+**
+** ^The column is identified by the second, third and fourth parameters to
+** this function. ^(The second parameter is either the name of the database
+** (i.e. "main", "temp", or an attached database) containing the specified
+** table or NULL.)^ ^If it is NULL, then all attached databases are searched
+** for the table using the same algorithm used by the database engine to
+** resolve unqualified table references.
+**
+** ^The third and fourth parameters to this function are the table and column
+** name of the desired column, respectively.
+**
+** ^Metadata is returned by writing to the memory locations passed as the 5th
+** and subsequent parameters to this function. ^Any of these arguments may be
+** NULL, in which case the corresponding element of metadata is omitted.
+**
+** ^(<blockquote>
+** <table border="1">
+** <tr><th> Parameter <th> Output<br>Type <th>  Description
+**
+** <tr><td> 5th <td> const char* <td> Data type
+** <tr><td> 6th <td> const char* <td> Name of default collation sequence
+** <tr><td> 7th <td> int         <td> True if column has a NOT NULL constraint
+** <tr><td> 8th <td> int         <td> True if column is part of the PRIMARY KEY
+** <tr><td> 9th <td> int         <td> True if column is [AUTOINCREMENT]
+** </table>
+** </blockquote>)^
+**
+** ^The memory pointed to by the character pointers returned for the
+** declaration type and collation sequence is valid until the next
+** call to any SQLite API function.
+**
+** ^If the specified table is actually a view, an [error code] is returned.
+**
+** ^If the specified column is "rowid", "oid" or "_rowid_" and the table 
+** is not a [WITHOUT ROWID] table and an
+** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output
+** parameters are set for the explicitly declared column. ^(If there is no
+** [INTEGER PRIMARY KEY] column, then the outputs
+** for the [rowid] are set as follows:
+**
+** <pre>
+**     data type: "INTEGER"
+**     collation sequence: "BINARY"
+**     not null: 0
+**     primary key: 1
+**     auto increment: 0
+** </pre>)^
+**
+** ^This function causes all database schemas to be read from disk and
+** parsed, if that has not already been done, and returns an error if
+** any errors are encountered while loading the schema.
+*/
+SQLITE_API int sqlite3_table_column_metadata(
+  sqlite3 *db,                /* Connection handle */
+  const char *zDbName,        /* Database name or NULL */
+  const char *zTableName,     /* Table name */
+  const char *zColumnName,    /* Column name */
+  char const **pzDataType,    /* OUTPUT: Declared data type */
+  char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
+  int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
+  int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
+  int *pAutoinc               /* OUTPUT: True if column is auto-increment */
+);
+
+/*
+** CAPI3REF: Load An Extension
+** METHOD: sqlite3
+**
+** ^This interface loads an SQLite extension library from the named file.
+**
+** ^The sqlite3_load_extension() interface attempts to load an
+** [SQLite extension] library contained in the file zFile.  If
+** the file cannot be loaded directly, attempts are made to load
+** with various operating-system specific extensions added.
+** So for example, if "samplelib" cannot be loaded, then names like
+** "samplelib.so" or "samplelib.dylib" or "samplelib.dll" might
+** be tried also.
+**
+** ^The entry point is zProc.
+** ^(zProc may be 0, in which case SQLite will try to come up with an
+** entry point name on its own.  It first tries "sqlite3_extension_init".
+** If that does not work, it constructs a name "sqlite3_X_init" where the
+** X is consists of the lower-case equivalent of all ASCII alphabetic
+** characters in the filename from the last "/" to the first following
+** "." and omitting any initial "lib".)^
+** ^The sqlite3_load_extension() interface returns
+** [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong.
+** ^If an error occurs and pzErrMsg is not 0, then the
+** [sqlite3_load_extension()] interface shall attempt to
+** fill *pzErrMsg with error message text stored in memory
+** obtained from [sqlite3_malloc()]. The calling function
+** should free this memory by calling [sqlite3_free()].
+**
+** ^Extension loading must be enabled using
+** [sqlite3_enable_load_extension()] or
+** [sqlite3_db_config](db,[SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION],1,NULL)
+** prior to calling this API,
+** otherwise an error will be returned.
+**
+** <b>Security warning:</b> It is recommended that the 
+** [SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION] method be used to enable only this
+** interface.  The use of the [sqlite3_enable_load_extension()] interface
+** should be avoided.  This will keep the SQL function [load_extension()]
+** disabled and prevent SQL injections from giving attackers
+** access to extension loading capabilities.
+**
+** See also the [load_extension() SQL function].
+*/
+SQLITE_API int sqlite3_load_extension(
+  sqlite3 *db,          /* Load the extension into this database connection */
+  const char *zFile,    /* Name of the shared library containing extension */
+  const char *zProc,    /* Entry point.  Derived from zFile if 0 */
+  char **pzErrMsg       /* Put error message here if not 0 */
+);
+
+/*
+** CAPI3REF: Enable Or Disable Extension Loading
+** METHOD: sqlite3
+**
+** ^So as not to open security holes in older applications that are
+** unprepared to deal with [extension loading], and as a means of disabling
+** [extension loading] while evaluating user-entered SQL, the following API
+** is provided to turn the [sqlite3_load_extension()] mechanism on and off.
+**
+** ^Extension loading is off by default.
+** ^Call the sqlite3_enable_load_extension() routine with onoff==1
+** to turn extension loading on and call it with onoff==0 to turn
+** it back off again.
+**
+** ^This interface enables or disables both the C-API
+** [sqlite3_load_extension()] and the SQL function [load_extension()].
+** ^(Use [sqlite3_db_config](db,[SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION],..)
+** to enable or disable only the C-API.)^
+**
+** <b>Security warning:</b> It is recommended that extension loading
+** be disabled using the [SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION] method
+** rather than this interface, so the [load_extension()] SQL function
+** remains disabled. This will prevent SQL injections from giving attackers
+** access to extension loading capabilities.
+*/
+SQLITE_API int sqlite3_enable_load_extension(sqlite3 *db, int onoff);
+
+/*
+** CAPI3REF: Automatically Load Statically Linked Extensions
+**
+** ^This interface causes the xEntryPoint() function to be invoked for
+** each new [database connection] that is created.  The idea here is that
+** xEntryPoint() is the entry point for a statically linked [SQLite extension]
+** that is to be automatically loaded into all new database connections.
+**
+** ^(Even though the function prototype shows that xEntryPoint() takes
+** no arguments and returns void, SQLite invokes xEntryPoint() with three
+** arguments and expects an integer result as if the signature of the
+** entry point where as follows:
+**
+** <blockquote><pre>
+** &nbsp;  int xEntryPoint(
+** &nbsp;    sqlite3 *db,
+** &nbsp;    const char **pzErrMsg,
+** &nbsp;    const struct sqlite3_api_routines *pThunk
+** &nbsp;  );
+** </pre></blockquote>)^
+**
+** If the xEntryPoint routine encounters an error, it should make *pzErrMsg
+** point to an appropriate error message (obtained from [sqlite3_mprintf()])
+** and return an appropriate [error code].  ^SQLite ensures that *pzErrMsg
+** is NULL before calling the xEntryPoint().  ^SQLite will invoke
+** [sqlite3_free()] on *pzErrMsg after xEntryPoint() returns.  ^If any
+** xEntryPoint() returns an error, the [sqlite3_open()], [sqlite3_open16()],
+** or [sqlite3_open_v2()] call that provoked the xEntryPoint() will fail.
+**
+** ^Calling sqlite3_auto_extension(X) with an entry point X that is already
+** on the list of automatic extensions is a harmless no-op. ^No entry point
+** will be called more than once for each database connection that is opened.
+**
+** See also: [sqlite3_reset_auto_extension()]
+** and [sqlite3_cancel_auto_extension()]
+*/
+SQLITE_API int sqlite3_auto_extension(void(*xEntryPoint)(void));
+
+/*
+** CAPI3REF: Cancel Automatic Extension Loading
+**
+** ^The [sqlite3_cancel_auto_extension(X)] interface unregisters the
+** initialization routine X that was registered using a prior call to
+** [sqlite3_auto_extension(X)].  ^The [sqlite3_cancel_auto_extension(X)]
+** routine returns 1 if initialization routine X was successfully 
+** unregistered and it returns 0 if X was not on the list of initialization
+** routines.
+*/
+SQLITE_API int sqlite3_cancel_auto_extension(void(*xEntryPoint)(void));
+
+/*
+** CAPI3REF: Reset Automatic Extension Loading
+**
+** ^This interface disables all automatic extensions previously
+** registered using [sqlite3_auto_extension()].
+*/
+SQLITE_API void sqlite3_reset_auto_extension(void);
+
+/*
+** The interface to the virtual-table mechanism is currently considered
+** to be experimental.  The interface might change in incompatible ways.
+** If this is a problem for you, do not use the interface at this time.
+**
+** When the virtual-table mechanism stabilizes, we will declare the
+** interface fixed, support it indefinitely, and remove this comment.
+*/
+
+/*
+** Structures used by the virtual table interface
+*/
+typedef struct sqlite3_vtab sqlite3_vtab;
+typedef struct sqlite3_index_info sqlite3_index_info;
+typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
+typedef struct sqlite3_module sqlite3_module;
+
+/*
+** CAPI3REF: Virtual Table Object
+** KEYWORDS: sqlite3_module {virtual table module}
+**
+** This structure, sometimes called a "virtual table module", 
+** defines the implementation of a [virtual tables].  
+** This structure consists mostly of methods for the module.
+**
+** ^A virtual table module is created by filling in a persistent
+** instance of this structure and passing a pointer to that instance
+** to [sqlite3_create_module()] or [sqlite3_create_module_v2()].
+** ^The registration remains valid until it is replaced by a different
+** module or until the [database connection] closes.  The content
+** of this structure must not change while it is registered with
+** any database connection.
+*/
+struct sqlite3_module {
+  int iVersion;
+  int (*xCreate)(sqlite3*, void *pAux,
+               int argc, const char *const*argv,
+               sqlite3_vtab **ppVTab, char**);
+  int (*xConnect)(sqlite3*, void *pAux,
+               int argc, const char *const*argv,
+               sqlite3_vtab **ppVTab, char**);
+  int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*);
+  int (*xDisconnect)(sqlite3_vtab *pVTab);
+  int (*xDestroy)(sqlite3_vtab *pVTab);
+  int (*xOpen)(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor);
+  int (*xClose)(sqlite3_vtab_cursor*);
+  int (*xFilter)(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
+                int argc, sqlite3_value **argv);
+  int (*xNext)(sqlite3_vtab_cursor*);
+  int (*xEof)(sqlite3_vtab_cursor*);
+  int (*xColumn)(sqlite3_vtab_cursor*, sqlite3_context*, int);
+  int (*xRowid)(sqlite3_vtab_cursor*, sqlite3_int64 *pRowid);
+  int (*xUpdate)(sqlite3_vtab *, int, sqlite3_value **, sqlite3_int64 *);
+  int (*xBegin)(sqlite3_vtab *pVTab);
+  int (*xSync)(sqlite3_vtab *pVTab);
+  int (*xCommit)(sqlite3_vtab *pVTab);
+  int (*xRollback)(sqlite3_vtab *pVTab);
+  int (*xFindFunction)(sqlite3_vtab *pVtab, int nArg, const char *zName,
+                       void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
+                       void **ppArg);
+  int (*xRename)(sqlite3_vtab *pVtab, const char *zNew);
+  /* The methods above are in version 1 of the sqlite_module object. Those 
+  ** below are for version 2 and greater. */
+  int (*xSavepoint)(sqlite3_vtab *pVTab, int);
+  int (*xRelease)(sqlite3_vtab *pVTab, int);
+  int (*xRollbackTo)(sqlite3_vtab *pVTab, int);
+};
+
+/*
+** CAPI3REF: Virtual Table Indexing Information
+** KEYWORDS: sqlite3_index_info
+**
+** The sqlite3_index_info structure and its substructures is used as part
+** of the [virtual table] interface to
+** pass information into and receive the reply from the [xBestIndex]
+** method of a [virtual table module].  The fields under **Inputs** are the
+** inputs to xBestIndex and are read-only.  xBestIndex inserts its
+** results into the **Outputs** fields.
+**
+** ^(The aConstraint[] array records WHERE clause constraints of the form:
+**
+** <blockquote>column OP expr</blockquote>
+**
+** where OP is =, &lt;, &lt;=, &gt;, or &gt;=.)^  ^(The particular operator is
+** stored in aConstraint[].op using one of the
+** [SQLITE_INDEX_CONSTRAINT_EQ | SQLITE_INDEX_CONSTRAINT_ values].)^
+** ^(The index of the column is stored in
+** aConstraint[].iColumn.)^  ^(aConstraint[].usable is TRUE if the
+** expr on the right-hand side can be evaluated (and thus the constraint
+** is usable) and false if it cannot.)^
+**
+** ^The optimizer automatically inverts terms of the form "expr OP column"
+** and makes other simplifications to the WHERE clause in an attempt to
+** get as many WHERE clause terms into the form shown above as possible.
+** ^The aConstraint[] array only reports WHERE clause terms that are
+** relevant to the particular virtual table being queried.
+**
+** ^Information about the ORDER BY clause is stored in aOrderBy[].
+** ^Each term of aOrderBy records a column of the ORDER BY clause.
+**
+** The colUsed field indicates which columns of the virtual table may be
+** required by the current scan. Virtual table columns are numbered from
+** zero in the order in which they appear within the CREATE TABLE statement
+** passed to sqlite3_declare_vtab(). For the first 63 columns (columns 0-62),
+** the corresponding bit is set within the colUsed mask if the column may be
+** required by SQLite. If the table has at least 64 columns and any column
+** to the right of the first 63 is required, then bit 63 of colUsed is also
+** set. In other words, column iCol may be required if the expression
+** (colUsed & ((sqlite3_uint64)1 << (iCol>=63 ? 63 : iCol))) evaluates to 
+** non-zero.
+**
+** The [xBestIndex] method must fill aConstraintUsage[] with information
+** about what parameters to pass to xFilter.  ^If argvIndex>0 then
+** the right-hand side of the corresponding aConstraint[] is evaluated
+** and becomes the argvIndex-th entry in argv.  ^(If aConstraintUsage[].omit
+** is true, then the constraint is assumed to be fully handled by the
+** virtual table and is not checked again by SQLite.)^
+**
+** ^The idxNum and idxPtr values are recorded and passed into the
+** [xFilter] method.
+** ^[sqlite3_free()] is used to free idxPtr if and only if
+** needToFreeIdxPtr is true.
+**
+** ^The orderByConsumed means that output from [xFilter]/[xNext] will occur in
+** the correct order to satisfy the ORDER BY clause so that no separate
+** sorting step is required.
+**
+** ^The estimatedCost value is an estimate of the cost of a particular
+** strategy. A cost of N indicates that the cost of the strategy is similar
+** to a linear scan of an SQLite table with N rows. A cost of log(N) 
+** indicates that the expense of the operation is similar to that of a
+** binary search on a unique indexed field of an SQLite table with N rows.
+**
+** ^The estimatedRows value is an estimate of the number of rows that
+** will be returned by the strategy.
+**
+** The xBestIndex method may optionally populate the idxFlags field with a 
+** mask of SQLITE_INDEX_SCAN_* flags. Currently there is only one such flag -
+** SQLITE_INDEX_SCAN_UNIQUE. If the xBestIndex method sets this flag, SQLite
+** assumes that the strategy may visit at most one row. 
+**
+** Additionally, if xBestIndex sets the SQLITE_INDEX_SCAN_UNIQUE flag, then
+** SQLite also assumes that if a call to the xUpdate() method is made as
+** part of the same statement to delete or update a virtual table row and the
+** implementation returns SQLITE_CONSTRAINT, then there is no need to rollback
+** any database changes. In other words, if the xUpdate() returns
+** SQLITE_CONSTRAINT, the database contents must be exactly as they were
+** before xUpdate was called. By contrast, if SQLITE_INDEX_SCAN_UNIQUE is not
+** set and xUpdate returns SQLITE_CONSTRAINT, any database changes made by
+** the xUpdate method are automatically rolled back by SQLite.
+**
+** IMPORTANT: The estimatedRows field was added to the sqlite3_index_info
+** structure for SQLite [version 3.8.2] ([dateof:3.8.2]). 
+** If a virtual table extension is
+** used with an SQLite version earlier than 3.8.2, the results of attempting 
+** to read or write the estimatedRows field are undefined (but are likely 
+** to included crashing the application). The estimatedRows field should
+** therefore only be used if [sqlite3_libversion_number()] returns a
+** value greater than or equal to 3008002. Similarly, the idxFlags field
+** was added for [version 3.9.0] ([dateof:3.9.0]). 
+** It may therefore only be used if
+** sqlite3_libversion_number() returns a value greater than or equal to
+** 3009000.
+*/
+struct sqlite3_index_info {
+  /* Inputs */
+  int nConstraint;           /* Number of entries in aConstraint */
+  struct sqlite3_index_constraint {
+     int iColumn;              /* Column constrained.  -1 for ROWID */
+     unsigned char op;         /* Constraint operator */
+     unsigned char usable;     /* True if this constraint is usable */
+     int iTermOffset;          /* Used internally - xBestIndex should ignore */
+  } *aConstraint;            /* Table of WHERE clause constraints */
+  int nOrderBy;              /* Number of terms in the ORDER BY clause */
+  struct sqlite3_index_orderby {
+     int iColumn;              /* Column number */
+     unsigned char desc;       /* True for DESC.  False for ASC. */
+  } *aOrderBy;               /* The ORDER BY clause */
+  /* Outputs */
+  struct sqlite3_index_constraint_usage {
+    int argvIndex;           /* if >0, constraint is part of argv to xFilter */
+    unsigned char omit;      /* Do not code a test for this constraint */
+  } *aConstraintUsage;
+  int idxNum;                /* Number used to identify the index */
+  char *idxStr;              /* String, possibly obtained from sqlite3_malloc */
+  int needToFreeIdxStr;      /* Free idxStr using sqlite3_free() if true */
+  int orderByConsumed;       /* True if output is already ordered */
+  double estimatedCost;           /* Estimated cost of using this index */
+  /* Fields below are only available in SQLite 3.8.2 and later */
+  sqlite3_int64 estimatedRows;    /* Estimated number of rows returned */
+  /* Fields below are only available in SQLite 3.9.0 and later */
+  int idxFlags;              /* Mask of SQLITE_INDEX_SCAN_* flags */
+  /* Fields below are only available in SQLite 3.10.0 and later */
+  sqlite3_uint64 colUsed;    /* Input: Mask of columns used by statement */
+};
+
+/*
+** CAPI3REF: Virtual Table Scan Flags
+*/
+#define SQLITE_INDEX_SCAN_UNIQUE      1     /* Scan visits at most 1 row */
+
+/*
+** CAPI3REF: Virtual Table Constraint Operator Codes
+**
+** These macros defined the allowed values for the
+** [sqlite3_index_info].aConstraint[].op field.  Each value represents
+** an operator that is part of a constraint term in the wHERE clause of
+** a query that uses a [virtual table].
+*/
+#define SQLITE_INDEX_CONSTRAINT_EQ      2
+#define SQLITE_INDEX_CONSTRAINT_GT      4
+#define SQLITE_INDEX_CONSTRAINT_LE      8
+#define SQLITE_INDEX_CONSTRAINT_LT     16
+#define SQLITE_INDEX_CONSTRAINT_GE     32
+#define SQLITE_INDEX_CONSTRAINT_MATCH  64
+#define SQLITE_INDEX_CONSTRAINT_LIKE   65
+#define SQLITE_INDEX_CONSTRAINT_GLOB   66
+#define SQLITE_INDEX_CONSTRAINT_REGEXP 67
+
+/*
+** CAPI3REF: Register A Virtual Table Implementation
+** METHOD: sqlite3
+**
+** ^These routines are used to register a new [virtual table module] name.
+** ^Module names must be registered before
+** creating a new [virtual table] using the module and before using a
+** preexisting [virtual table] for the module.
+**
+** ^The module name is registered on the [database connection] specified
+** by the first parameter.  ^The name of the module is given by the 
+** second parameter.  ^The third parameter is a pointer to
+** the implementation of the [virtual table module].   ^The fourth
+** parameter is an arbitrary client data pointer that is passed through
+** into the [xCreate] and [xConnect] methods of the virtual table module
+** when a new virtual table is be being created or reinitialized.
+**
+** ^The sqlite3_create_module_v2() interface has a fifth parameter which
+** is a pointer to a destructor for the pClientData.  ^SQLite will
+** invoke the destructor function (if it is not NULL) when SQLite
+** no longer needs the pClientData pointer.  ^The destructor will also
+** be invoked if the call to sqlite3_create_module_v2() fails.
+** ^The sqlite3_create_module()
+** interface is equivalent to sqlite3_create_module_v2() with a NULL
+** destructor.
+*/
+SQLITE_API int sqlite3_create_module(
+  sqlite3 *db,               /* SQLite connection to register module with */
+  const char *zName,         /* Name of the module */
+  const sqlite3_module *p,   /* Methods for the module */
+  void *pClientData          /* Client data for xCreate/xConnect */
+);
+SQLITE_API int sqlite3_create_module_v2(
+  sqlite3 *db,               /* SQLite connection to register module with */
+  const char *zName,         /* Name of the module */
+  const sqlite3_module *p,   /* Methods for the module */
+  void *pClientData,         /* Client data for xCreate/xConnect */
+  void(*xDestroy)(void*)     /* Module destructor function */
+);
+
+/*
+** CAPI3REF: Virtual Table Instance Object
+** KEYWORDS: sqlite3_vtab
+**
+** Every [virtual table module] implementation uses a subclass
+** of this object to describe a particular instance
+** of the [virtual table].  Each subclass will
+** be tailored to the specific needs of the module implementation.
+** The purpose of this superclass is to define certain fields that are
+** common to all module implementations.
+**
+** ^Virtual tables methods can set an error message by assigning a
+** string obtained from [sqlite3_mprintf()] to zErrMsg.  The method should
+** take care that any prior string is freed by a call to [sqlite3_free()]
+** prior to assigning a new string to zErrMsg.  ^After the error message
+** is delivered up to the client application, the string will be automatically
+** freed by sqlite3_free() and the zErrMsg field will be zeroed.
+*/
+struct sqlite3_vtab {
+  const sqlite3_module *pModule;  /* The module for this virtual table */
+  int nRef;                       /* Number of open cursors */
+  char *zErrMsg;                  /* Error message from sqlite3_mprintf() */
+  /* Virtual table implementations will typically add additional fields */
+};
+
+/*
+** CAPI3REF: Virtual Table Cursor Object
+** KEYWORDS: sqlite3_vtab_cursor {virtual table cursor}
+**
+** Every [virtual table module] implementation uses a subclass of the
+** following structure to describe cursors that point into the
+** [virtual table] and are used
+** to loop through the virtual table.  Cursors are created using the
+** [sqlite3_module.xOpen | xOpen] method of the module and are destroyed
+** by the [sqlite3_module.xClose | xClose] method.  Cursors are used
+** by the [xFilter], [xNext], [xEof], [xColumn], and [xRowid] methods
+** of the module.  Each module implementation will define
+** the content of a cursor structure to suit its own needs.
+**
+** This superclass exists in order to define fields of the cursor that
+** are common to all implementations.
+*/
+struct sqlite3_vtab_cursor {
+  sqlite3_vtab *pVtab;      /* Virtual table of this cursor */
+  /* Virtual table implementations will typically add additional fields */
+};
+
+/*
+** CAPI3REF: Declare The Schema Of A Virtual Table
+**
+** ^The [xCreate] and [xConnect] methods of a
+** [virtual table module] call this interface
+** to declare the format (the names and datatypes of the columns) of
+** the virtual tables they implement.
+*/
+SQLITE_API int sqlite3_declare_vtab(sqlite3*, const char *zSQL);
+
+/*
+** CAPI3REF: Overload A Function For A Virtual Table
+** METHOD: sqlite3
+**
+** ^(Virtual tables can provide alternative implementations of functions
+** using the [xFindFunction] method of the [virtual table module].  
+** But global versions of those functions
+** must exist in order to be overloaded.)^
+**
+** ^(This API makes sure a global version of a function with a particular
+** name and number of parameters exists.  If no such function exists
+** before this API is called, a new function is created.)^  ^The implementation
+** of the new function always causes an exception to be thrown.  So
+** the new function is not good for anything by itself.  Its only
+** purpose is to be a placeholder function that can be overloaded
+** by a [virtual table].
+*/
+SQLITE_API int sqlite3_overload_function(sqlite3*, const char *zFuncName, int nArg);
+
+/*
+** The interface to the virtual-table mechanism defined above (back up
+** to a comment remarkably similar to this one) is currently considered
+** to be experimental.  The interface might change in incompatible ways.
+** If this is a problem for you, do not use the interface at this time.
+**
+** When the virtual-table mechanism stabilizes, we will declare the
+** interface fixed, support it indefinitely, and remove this comment.
+*/
+
+/*
+** CAPI3REF: A Handle To An Open BLOB
+** KEYWORDS: {BLOB handle} {BLOB handles}
+**
+** An instance of this object represents an open BLOB on which
+** [sqlite3_blob_open | incremental BLOB I/O] can be performed.
+** ^Objects of this type are created by [sqlite3_blob_open()]
+** and destroyed by [sqlite3_blob_close()].
+** ^The [sqlite3_blob_read()] and [sqlite3_blob_write()] interfaces
+** can be used to read or write small subsections of the BLOB.
+** ^The [sqlite3_blob_bytes()] interface returns the size of the BLOB in bytes.
+*/
+typedef struct sqlite3_blob sqlite3_blob;
+
+/*
+** CAPI3REF: Open A BLOB For Incremental I/O
+** METHOD: sqlite3
+** CONSTRUCTOR: sqlite3_blob
+**
+** ^(This interfaces opens a [BLOB handle | handle] to the BLOB located
+** in row iRow, column zColumn, table zTable in database zDb;
+** in other words, the same BLOB that would be selected by:
+**
+** <pre>
+**     SELECT zColumn FROM zDb.zTable WHERE [rowid] = iRow;
+** </pre>)^
+**
+** ^(Parameter zDb is not the filename that contains the database, but 
+** rather the symbolic name of the database. For attached databases, this is
+** the name that appears after the AS keyword in the [ATTACH] statement.
+** For the main database file, the database name is "main". For TEMP
+** tables, the database name is "temp".)^
+**
+** ^If the flags parameter is non-zero, then the BLOB is opened for read
+** and write access. ^If the flags parameter is zero, the BLOB is opened for
+** read-only access.
+**
+** ^(On success, [SQLITE_OK] is returned and the new [BLOB handle] is stored
+** in *ppBlob. Otherwise an [error code] is returned and, unless the error
+** code is SQLITE_MISUSE, *ppBlob is set to NULL.)^ ^This means that, provided
+** the API is not misused, it is always safe to call [sqlite3_blob_close()] 
+** on *ppBlob after this function it returns.
+**
+** This function fails with SQLITE_ERROR if any of the following are true:
+** <ul>
+**   <li> ^(Database zDb does not exist)^, 
+**   <li> ^(Table zTable does not exist within database zDb)^, 
+**   <li> ^(Table zTable is a WITHOUT ROWID table)^, 
+**   <li> ^(Column zColumn does not exist)^,
+**   <li> ^(Row iRow is not present in the table)^,
+**   <li> ^(The specified column of row iRow contains a value that is not
+**         a TEXT or BLOB value)^,
+**   <li> ^(Column zColumn is part of an index, PRIMARY KEY or UNIQUE 
+**         constraint and the blob is being opened for read/write access)^,
+**   <li> ^([foreign key constraints | Foreign key constraints] are enabled, 
+**         column zColumn is part of a [child key] definition and the blob is
+**         being opened for read/write access)^.
+** </ul>
+**
+** ^Unless it returns SQLITE_MISUSE, this function sets the 
+** [database connection] error code and message accessible via 
+** [sqlite3_errcode()] and [sqlite3_errmsg()] and related functions. 
+**
+**
+** ^(If the row that a BLOB handle points to is modified by an
+** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
+** then the BLOB handle is marked as "expired".
+** This is true if any column of the row is changed, even a column
+** other than the one the BLOB handle is open on.)^
+** ^Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for
+** an expired BLOB handle fail with a return code of [SQLITE_ABORT].
+** ^(Changes written into a BLOB prior to the BLOB expiring are not
+** rolled back by the expiration of the BLOB.  Such changes will eventually
+** commit if the transaction continues to completion.)^
+**
+** ^Use the [sqlite3_blob_bytes()] interface to determine the size of
+** the opened blob.  ^The size of a blob may not be changed by this
+** interface.  Use the [UPDATE] SQL command to change the size of a
+** blob.
+**
+** ^The [sqlite3_bind_zeroblob()] and [sqlite3_result_zeroblob()] interfaces
+** and the built-in [zeroblob] SQL function may be used to create a 
+** zero-filled blob to read or write using the incremental-blob interface.
+**
+** To avoid a resource leak, every open [BLOB handle] should eventually
+** be released by a call to [sqlite3_blob_close()].
+*/
+SQLITE_API int sqlite3_blob_open(
+  sqlite3*,
+  const char *zDb,
+  const char *zTable,
+  const char *zColumn,
+  sqlite3_int64 iRow,
+  int flags,
+  sqlite3_blob **ppBlob
+);
+
+/*
+** CAPI3REF: Move a BLOB Handle to a New Row
+** METHOD: sqlite3_blob
+**
+** ^This function is used to move an existing blob handle so that it points
+** to a different row of the same database table. ^The new row is identified
+** by the rowid value passed as the second argument. Only the row can be
+** changed. ^The database, table and column on which the blob handle is open
+** remain the same. Moving an existing blob handle to a new row can be
+** faster than closing the existing handle and opening a new one.
+**
+** ^(The new row must meet the same criteria as for [sqlite3_blob_open()] -
+** it must exist and there must be either a blob or text value stored in
+** the nominated column.)^ ^If the new row is not present in the table, or if
+** it does not contain a blob or text value, or if another error occurs, an
+** SQLite error code is returned and the blob handle is considered aborted.
+** ^All subsequent calls to [sqlite3_blob_read()], [sqlite3_blob_write()] or
+** [sqlite3_blob_reopen()] on an aborted blob handle immediately return
+** SQLITE_ABORT. ^Calling [sqlite3_blob_bytes()] on an aborted blob handle
+** always returns zero.
+**
+** ^This function sets the database handle error code and message.
+*/
+SQLITE_API int sqlite3_blob_reopen(sqlite3_blob *, sqlite3_int64);
+
+/*
+** CAPI3REF: Close A BLOB Handle
+** DESTRUCTOR: sqlite3_blob
+**
+** ^This function closes an open [BLOB handle]. ^(The BLOB handle is closed
+** unconditionally.  Even if this routine returns an error code, the 
+** handle is still closed.)^
+**
+** ^If the blob handle being closed was opened for read-write access, and if
+** the database is in auto-commit mode and there are no other open read-write
+** blob handles or active write statements, the current transaction is
+** committed. ^If an error occurs while committing the transaction, an error
+** code is returned and the transaction rolled back.
+**
+** Calling this function with an argument that is not a NULL pointer or an
+** open blob handle results in undefined behaviour. ^Calling this routine 
+** with a null pointer (such as would be returned by a failed call to 
+** [sqlite3_blob_open()]) is a harmless no-op. ^Otherwise, if this function
+** is passed a valid open blob handle, the values returned by the 
+** sqlite3_errcode() and sqlite3_errmsg() functions are set before returning.
+*/
+SQLITE_API int sqlite3_blob_close(sqlite3_blob *);
+
+/*
+** CAPI3REF: Return The Size Of An Open BLOB
+** METHOD: sqlite3_blob
+**
+** ^Returns the size in bytes of the BLOB accessible via the 
+** successfully opened [BLOB handle] in its only argument.  ^The
+** incremental blob I/O routines can only read or overwriting existing
+** blob content; they cannot change the size of a blob.
+**
+** This routine only works on a [BLOB handle] which has been created
+** by a prior successful call to [sqlite3_blob_open()] and which has not
+** been closed by [sqlite3_blob_close()].  Passing any other pointer in
+** to this routine results in undefined and probably undesirable behavior.
+*/
+SQLITE_API int sqlite3_blob_bytes(sqlite3_blob *);
+
+/*
+** CAPI3REF: Read Data From A BLOB Incrementally
+** METHOD: sqlite3_blob
+**
+** ^(This function is used to read data from an open [BLOB handle] into a
+** caller-supplied buffer. N bytes of data are copied into buffer Z
+** from the open BLOB, starting at offset iOffset.)^
+**
+** ^If offset iOffset is less than N bytes from the end of the BLOB,
+** [SQLITE_ERROR] is returned and no data is read.  ^If N or iOffset is
+** less than zero, [SQLITE_ERROR] is returned and no data is read.
+** ^The size of the blob (and hence the maximum value of N+iOffset)
+** can be determined using the [sqlite3_blob_bytes()] interface.
+**
+** ^An attempt to read from an expired [BLOB handle] fails with an
+** error code of [SQLITE_ABORT].
+**
+** ^(On success, sqlite3_blob_read() returns SQLITE_OK.
+** Otherwise, an [error code] or an [extended error code] is returned.)^
+**
+** This routine only works on a [BLOB handle] which has been created
+** by a prior successful call to [sqlite3_blob_open()] and which has not
+** been closed by [sqlite3_blob_close()].  Passing any other pointer in
+** to this routine results in undefined and probably undesirable behavior.
+**
+** See also: [sqlite3_blob_write()].
+*/
+SQLITE_API int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);
+
+/*
+** CAPI3REF: Write Data Into A BLOB Incrementally
+** METHOD: sqlite3_blob
+**
+** ^(This function is used to write data into an open [BLOB handle] from a
+** caller-supplied buffer. N bytes of data are copied from the buffer Z
+** into the open BLOB, starting at offset iOffset.)^
+**
+** ^(On success, sqlite3_blob_write() returns SQLITE_OK.
+** Otherwise, an  [error code] or an [extended error code] is returned.)^
+** ^Unless SQLITE_MISUSE is returned, this function sets the 
+** [database connection] error code and message accessible via 
+** [sqlite3_errcode()] and [sqlite3_errmsg()] and related functions. 
+**
+** ^If the [BLOB handle] passed as the first argument was not opened for
+** writing (the flags parameter to [sqlite3_blob_open()] was zero),
+** this function returns [SQLITE_READONLY].
+**
+** This function may only modify the contents of the BLOB; it is
+** not possible to increase the size of a BLOB using this API.
+** ^If offset iOffset is less than N bytes from the end of the BLOB,
+** [SQLITE_ERROR] is returned and no data is written. The size of the 
+** BLOB (and hence the maximum value of N+iOffset) can be determined 
+** using the [sqlite3_blob_bytes()] interface. ^If N or iOffset are less 
+** than zero [SQLITE_ERROR] is returned and no data is written.
+**
+** ^An attempt to write to an expired [BLOB handle] fails with an
+** error code of [SQLITE_ABORT].  ^Writes to the BLOB that occurred
+** before the [BLOB handle] expired are not rolled back by the
+** expiration of the handle, though of course those changes might
+** have been overwritten by the statement that expired the BLOB handle
+** or by other independent statements.
+**
+** This routine only works on a [BLOB handle] which has been created
+** by a prior successful call to [sqlite3_blob_open()] and which has not
+** been closed by [sqlite3_blob_close()].  Passing any other pointer in
+** to this routine results in undefined and probably undesirable behavior.
+**
+** See also: [sqlite3_blob_read()].
+*/
+SQLITE_API int sqlite3_blob_write(sqlite3_blob *, const void *z, int n, int iOffset);
+
+/*
+** CAPI3REF: Virtual File System Objects
+**
+** A virtual filesystem (VFS) is an [sqlite3_vfs] object
+** that SQLite uses to interact
+** with the underlying operating system.  Most SQLite builds come with a
+** single default VFS that is appropriate for the host computer.
+** New VFSes can be registered and existing VFSes can be unregistered.
+** The following interfaces are provided.
+**
+** ^The sqlite3_vfs_find() interface returns a pointer to a VFS given its name.
+** ^Names are case sensitive.
+** ^Names are zero-terminated UTF-8 strings.
+** ^If there is no match, a NULL pointer is returned.
+** ^If zVfsName is NULL then the default VFS is returned.
+**
+** ^New VFSes are registered with sqlite3_vfs_register().
+** ^Each new VFS becomes the default VFS if the makeDflt flag is set.
+** ^The same VFS can be registered multiple times without injury.
+** ^To make an existing VFS into the default VFS, register it again
+** with the makeDflt flag set.  If two different VFSes with the
+** same name are registered, the behavior is undefined.  If a
+** VFS is registered with a name that is NULL or an empty string,
+** then the behavior is undefined.
+**
+** ^Unregister a VFS with the sqlite3_vfs_unregister() interface.
+** ^(If the default VFS is unregistered, another VFS is chosen as
+** the default.  The choice for the new VFS is arbitrary.)^
+*/
+SQLITE_API sqlite3_vfs *sqlite3_vfs_find(const char *zVfsName);
+SQLITE_API int sqlite3_vfs_register(sqlite3_vfs*, int makeDflt);
+SQLITE_API int sqlite3_vfs_unregister(sqlite3_vfs*);
+
+/*
+** CAPI3REF: Mutexes
+**
+** The SQLite core uses these routines for thread
+** synchronization. Though they are intended for internal
+** use by SQLite, code that links against SQLite is
+** permitted to use any of these routines.
+**
+** The SQLite source code contains multiple implementations
+** of these mutex routines.  An appropriate implementation
+** is selected automatically at compile-time.  The following
+** implementations are available in the SQLite core:
+**
+** <ul>
+** <li>   SQLITE_MUTEX_PTHREADS
+** <li>   SQLITE_MUTEX_W32
+** <li>   SQLITE_MUTEX_NOOP
+** </ul>
+**
+** The SQLITE_MUTEX_NOOP implementation is a set of routines
+** that does no real locking and is appropriate for use in
+** a single-threaded application.  The SQLITE_MUTEX_PTHREADS and
+** SQLITE_MUTEX_W32 implementations are appropriate for use on Unix
+** and Windows.
+**
+** If SQLite is compiled with the SQLITE_MUTEX_APPDEF preprocessor
+** macro defined (with "-DSQLITE_MUTEX_APPDEF=1"), then no mutex
+** implementation is included with the library. In this case the
+** application must supply a custom mutex implementation using the
+** [SQLITE_CONFIG_MUTEX] option of the sqlite3_config() function
+** before calling sqlite3_initialize() or any other public sqlite3_
+** function that calls sqlite3_initialize().
+**
+** ^The sqlite3_mutex_alloc() routine allocates a new
+** mutex and returns a pointer to it. ^The sqlite3_mutex_alloc()
+** routine returns NULL if it is unable to allocate the requested
+** mutex.  The argument to sqlite3_mutex_alloc() must one of these
+** integer constants:
+**
+** <ul>
+** <li>  SQLITE_MUTEX_FAST
+** <li>  SQLITE_MUTEX_RECURSIVE
+** <li>  SQLITE_MUTEX_STATIC_MASTER
+** <li>  SQLITE_MUTEX_STATIC_MEM
+** <li>  SQLITE_MUTEX_STATIC_OPEN
+** <li>  SQLITE_MUTEX_STATIC_PRNG
+** <li>  SQLITE_MUTEX_STATIC_LRU
+** <li>  SQLITE_MUTEX_STATIC_PMEM
+** <li>  SQLITE_MUTEX_STATIC_APP1
+** <li>  SQLITE_MUTEX_STATIC_APP2
+** <li>  SQLITE_MUTEX_STATIC_APP3
+** <li>  SQLITE_MUTEX_STATIC_VFS1
+** <li>  SQLITE_MUTEX_STATIC_VFS2
+** <li>  SQLITE_MUTEX_STATIC_VFS3
+** </ul>
+**
+** ^The first two constants (SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE)
+** cause sqlite3_mutex_alloc() to create
+** a new mutex.  ^The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
+** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
+** The mutex implementation does not need to make a distinction
+** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
+** not want to.  SQLite will only request a recursive mutex in
+** cases where it really needs one.  If a faster non-recursive mutex
+** implementation is available on the host platform, the mutex subsystem
+** might return such a mutex in response to SQLITE_MUTEX_FAST.
+**
+** ^The other allowed parameters to sqlite3_mutex_alloc() (anything other
+** than SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE) each return
+** a pointer to a static preexisting mutex.  ^Nine static mutexes are
+** used by the current version of SQLite.  Future versions of SQLite
+** may add additional static mutexes.  Static mutexes are for internal
+** use by SQLite only.  Applications that use SQLite mutexes should
+** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
+** SQLITE_MUTEX_RECURSIVE.
+**
+** ^Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
+** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
+** returns a different mutex on every call.  ^For the static
+** mutex types, the same mutex is returned on every call that has
+** the same type number.
+**
+** ^The sqlite3_mutex_free() routine deallocates a previously
+** allocated dynamic mutex.  Attempting to deallocate a static
+** mutex results in undefined behavior.
+**
+** ^The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
+** to enter a mutex.  ^If another thread is already within the mutex,
+** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
+** SQLITE_BUSY.  ^The sqlite3_mutex_try() interface returns [SQLITE_OK]
+** upon successful entry.  ^(Mutexes created using
+** SQLITE_MUTEX_RECURSIVE can be entered multiple times by the same thread.
+** In such cases, the
+** mutex must be exited an equal number of times before another thread
+** can enter.)^  If the same thread tries to enter any mutex other
+** than an SQLITE_MUTEX_RECURSIVE more than once, the behavior is undefined.
+**
+** ^(Some systems (for example, Windows 95) do not support the operation
+** implemented by sqlite3_mutex_try().  On those systems, sqlite3_mutex_try()
+** will always return SQLITE_BUSY. The SQLite core only ever uses
+** sqlite3_mutex_try() as an optimization so this is acceptable 
+** behavior.)^
+**
+** ^The sqlite3_mutex_leave() routine exits a mutex that was
+** previously entered by the same thread.   The behavior
+** is undefined if the mutex is not currently entered by the
+** calling thread or is not currently allocated.
+**
+** ^If the argument to sqlite3_mutex_enter(), sqlite3_mutex_try(), or
+** sqlite3_mutex_leave() is a NULL pointer, then all three routines
+** behave as no-ops.
+**
+** See also: [sqlite3_mutex_held()] and [sqlite3_mutex_notheld()].
+*/
+SQLITE_API sqlite3_mutex *sqlite3_mutex_alloc(int);
+SQLITE_API void sqlite3_mutex_free(sqlite3_mutex*);
+SQLITE_API void sqlite3_mutex_enter(sqlite3_mutex*);
+SQLITE_API int sqlite3_mutex_try(sqlite3_mutex*);
+SQLITE_API void sqlite3_mutex_leave(sqlite3_mutex*);
+
+/*
+** CAPI3REF: Mutex Methods Object
+**
+** An instance of this structure defines the low-level routines
+** used to allocate and use mutexes.
+**
+** Usually, the default mutex implementations provided by SQLite are
+** sufficient, however the application has the option of substituting a custom
+** implementation for specialized deployments or systems for which SQLite
+** does not provide a suitable implementation. In this case, the application
+** creates and populates an instance of this structure to pass
+** to sqlite3_config() along with the [SQLITE_CONFIG_MUTEX] option.
+** Additionally, an instance of this structure can be used as an
+** output variable when querying the system for the current mutex
+** implementation, using the [SQLITE_CONFIG_GETMUTEX] option.
+**
+** ^The xMutexInit method defined by this structure is invoked as
+** part of system initialization by the sqlite3_initialize() function.
+** ^The xMutexInit routine is called by SQLite exactly once for each
+** effective call to [sqlite3_initialize()].
+**
+** ^The xMutexEnd method defined by this structure is invoked as
+** part of system shutdown by the sqlite3_shutdown() function. The
+** implementation of this method is expected to release all outstanding
+** resources obtained by the mutex methods implementation, especially
+** those obtained by the xMutexInit method.  ^The xMutexEnd()
+** interface is invoked exactly once for each call to [sqlite3_shutdown()].
+**
+** ^(The remaining seven methods defined by this structure (xMutexAlloc,
+** xMutexFree, xMutexEnter, xMutexTry, xMutexLeave, xMutexHeld and
+** xMutexNotheld) implement the following interfaces (respectively):
+**
+** <ul>
+**   <li>  [sqlite3_mutex_alloc()] </li>
+**   <li>  [sqlite3_mutex_free()] </li>
+**   <li>  [sqlite3_mutex_enter()] </li>
+**   <li>  [sqlite3_mutex_try()] </li>
+**   <li>  [sqlite3_mutex_leave()] </li>
+**   <li>  [sqlite3_mutex_held()] </li>
+**   <li>  [sqlite3_mutex_notheld()] </li>
+** </ul>)^
+**
+** The only difference is that the public sqlite3_XXX functions enumerated
+** above silently ignore any invocations that pass a NULL pointer instead
+** of a valid mutex handle. The implementations of the methods defined
+** by this structure are not required to handle this case, the results
+** of passing a NULL pointer instead of a valid mutex handle are undefined
+** (i.e. it is acceptable to provide an implementation that segfaults if
+** it is passed a NULL pointer).
+**
+** The xMutexInit() method must be threadsafe.  It must be harmless to
+** invoke xMutexInit() multiple times within the same process and without
+** intervening calls to xMutexEnd().  Second and subsequent calls to
+** xMutexInit() must be no-ops.
+**
+** xMutexInit() must not use SQLite memory allocation ([sqlite3_malloc()]
+** and its associates).  Similarly, xMutexAlloc() must not use SQLite memory
+** allocation for a static mutex.  ^However xMutexAlloc() may use SQLite
+** memory allocation for a fast or recursive mutex.
+**
+** ^SQLite will invoke the xMutexEnd() method when [sqlite3_shutdown()] is
+** called, but only if the prior call to xMutexInit returned SQLITE_OK.
+** If xMutexInit fails in any way, it is expected to clean up after itself
+** prior to returning.
+*/
+typedef struct sqlite3_mutex_methods sqlite3_mutex_methods;
+struct sqlite3_mutex_methods {
+  int (*xMutexInit)(void);
+  int (*xMutexEnd)(void);
+  sqlite3_mutex *(*xMutexAlloc)(int);
+  void (*xMutexFree)(sqlite3_mutex *);
+  void (*xMutexEnter)(sqlite3_mutex *);
+  int (*xMutexTry)(sqlite3_mutex *);
+  void (*xMutexLeave)(sqlite3_mutex *);
+  int (*xMutexHeld)(sqlite3_mutex *);
+  int (*xMutexNotheld)(sqlite3_mutex *);
+};
+
+/*
+** CAPI3REF: Mutex Verification Routines
+**
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routines
+** are intended for use inside assert() statements.  The SQLite core
+** never uses these routines except inside an assert() and applications
+** are advised to follow the lead of the core.  The SQLite core only
+** provides implementations for these routines when it is compiled
+** with the SQLITE_DEBUG flag.  External mutex implementations
+** are only required to provide these routines if SQLITE_DEBUG is
+** defined and if NDEBUG is not defined.
+**
+** These routines should return true if the mutex in their argument
+** is held or not held, respectively, by the calling thread.
+**
+** The implementation is not required to provide versions of these
+** routines that actually work. If the implementation does not provide working
+** versions of these routines, it should at least provide stubs that always
+** return true so that one does not get spurious assertion failures.
+**
+** If the argument to sqlite3_mutex_held() is a NULL pointer then
+** the routine should return 1.   This seems counter-intuitive since
+** clearly the mutex cannot be held if it does not exist.  But
+** the reason the mutex does not exist is because the build is not
+** using mutexes.  And we do not want the assert() containing the
+** call to sqlite3_mutex_held() to fail, so a non-zero return is
+** the appropriate thing to do.  The sqlite3_mutex_notheld()
+** interface should also return 1 when given a NULL pointer.
+*/
+#ifndef NDEBUG
+SQLITE_API int sqlite3_mutex_held(sqlite3_mutex*);
+SQLITE_API int sqlite3_mutex_notheld(sqlite3_mutex*);
+#endif
+
+/*
+** CAPI3REF: Mutex Types
+**
+** The [sqlite3_mutex_alloc()] interface takes a single argument
+** which is one of these integer constants.
+**
+** The set of static mutexes may change from one SQLite release to the
+** next.  Applications that override the built-in mutex logic must be
+** prepared to accommodate additional static mutexes.
+*/
+#define SQLITE_MUTEX_FAST             0
+#define SQLITE_MUTEX_RECURSIVE        1
+#define SQLITE_MUTEX_STATIC_MASTER    2
+#define SQLITE_MUTEX_STATIC_MEM       3  /* sqlite3_malloc() */
+#define SQLITE_MUTEX_STATIC_MEM2      4  /* NOT USED */
+#define SQLITE_MUTEX_STATIC_OPEN      4  /* sqlite3BtreeOpen() */
+#define SQLITE_MUTEX_STATIC_PRNG      5  /* sqlite3_randomness() */
+#define SQLITE_MUTEX_STATIC_LRU       6  /* lru page list */
+#define SQLITE_MUTEX_STATIC_LRU2      7  /* NOT USED */
+#define SQLITE_MUTEX_STATIC_PMEM      7  /* sqlite3PageMalloc() */
+#define SQLITE_MUTEX_STATIC_APP1      8  /* For use by application */
+#define SQLITE_MUTEX_STATIC_APP2      9  /* For use by application */
+#define SQLITE_MUTEX_STATIC_APP3     10  /* For use by application */
+#define SQLITE_MUTEX_STATIC_VFS1     11  /* For use by built-in VFS */
+#define SQLITE_MUTEX_STATIC_VFS2     12  /* For use by extension VFS */
+#define SQLITE_MUTEX_STATIC_VFS3     13  /* For use by application VFS */
+
+/*
+** CAPI3REF: Retrieve the mutex for a database connection
+** METHOD: sqlite3
+**
+** ^This interface returns a pointer the [sqlite3_mutex] object that 
+** serializes access to the [database connection] given in the argument
+** when the [threading mode] is Serialized.
+** ^If the [threading mode] is Single-thread or Multi-thread then this
+** routine returns a NULL pointer.
+*/
+SQLITE_API sqlite3_mutex *sqlite3_db_mutex(sqlite3*);
+
+/*
+** CAPI3REF: Low-Level Control Of Database Files
+** METHOD: sqlite3
+**
+** ^The [sqlite3_file_control()] interface makes a direct call to the
+** xFileControl method for the [sqlite3_io_methods] object associated
+** with a particular database identified by the second argument. ^The
+** name of the database is "main" for the main database or "temp" for the
+** TEMP database, or the name that appears after the AS keyword for
+** databases that are added using the [ATTACH] SQL command.
+** ^A NULL pointer can be used in place of "main" to refer to the
+** main database file.
+** ^The third and fourth parameters to this routine
+** are passed directly through to the second and third parameters of
+** the xFileControl method.  ^The return value of the xFileControl
+** method becomes the return value of this routine.
+**
+** ^The SQLITE_FCNTL_FILE_POINTER value for the op parameter causes
+** a pointer to the underlying [sqlite3_file] object to be written into
+** the space pointed to by the 4th parameter.  ^The SQLITE_FCNTL_FILE_POINTER
+** case is a short-circuit path which does not actually invoke the
+** underlying sqlite3_io_methods.xFileControl method.
+**
+** ^If the second parameter (zDbName) does not match the name of any
+** open database file, then SQLITE_ERROR is returned.  ^This error
+** code is not remembered and will not be recalled by [sqlite3_errcode()]
+** or [sqlite3_errmsg()].  The underlying xFileControl method might
+** also return SQLITE_ERROR.  There is no way to distinguish between
+** an incorrect zDbName and an SQLITE_ERROR return from the underlying
+** xFileControl method.
+**
+** See also: [SQLITE_FCNTL_LOCKSTATE]
+*/
+SQLITE_API int sqlite3_file_control(sqlite3*, const char *zDbName, int op, void*);
+
+/*
+** CAPI3REF: Testing Interface
+**
+** ^The sqlite3_test_control() interface is used to read out internal
+** state of SQLite and to inject faults into SQLite for testing
+** purposes.  ^The first parameter is an operation code that determines
+** the number, meaning, and operation of all subsequent parameters.
+**
+** This interface is not for use by applications.  It exists solely
+** for verifying the correct operation of the SQLite library.  Depending
+** on how the SQLite library is compiled, this interface might not exist.
+**
+** The details of the operation codes, their meanings, the parameters
+** they take, and what they do are all subject to change without notice.
+** Unlike most of the SQLite API, this function is not guaranteed to
+** operate consistently from one release to the next.
+*/
+SQLITE_API int sqlite3_test_control(int op, ...);
+
+/*
+** CAPI3REF: Testing Interface Operation Codes
+**
+** These constants are the valid operation code parameters used
+** as the first argument to [sqlite3_test_control()].
+**
+** These parameters and their meanings are subject to change
+** without notice.  These values are for testing purposes only.
+** Applications should not use any of these parameters or the
+** [sqlite3_test_control()] interface.
+*/
+#define SQLITE_TESTCTRL_FIRST                    5
+#define SQLITE_TESTCTRL_PRNG_SAVE                5
+#define SQLITE_TESTCTRL_PRNG_RESTORE             6
+#define SQLITE_TESTCTRL_PRNG_RESET               7
+#define SQLITE_TESTCTRL_BITVEC_TEST              8
+#define SQLITE_TESTCTRL_FAULT_INSTALL            9
+#define SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS     10
+#define SQLITE_TESTCTRL_PENDING_BYTE            11
+#define SQLITE_TESTCTRL_ASSERT                  12
+#define SQLITE_TESTCTRL_ALWAYS                  13
+#define SQLITE_TESTCTRL_RESERVE                 14
+#define SQLITE_TESTCTRL_OPTIMIZATIONS           15
+#define SQLITE_TESTCTRL_ISKEYWORD               16
+#define SQLITE_TESTCTRL_SCRATCHMALLOC           17
+#define SQLITE_TESTCTRL_LOCALTIME_FAULT         18
+#define SQLITE_TESTCTRL_EXPLAIN_STMT            19  /* NOT USED */
+#define SQLITE_TESTCTRL_ONCE_RESET_THRESHOLD    19
+#define SQLITE_TESTCTRL_NEVER_CORRUPT           20
+#define SQLITE_TESTCTRL_VDBE_COVERAGE           21
+#define SQLITE_TESTCTRL_BYTEORDER               22
+#define SQLITE_TESTCTRL_ISINIT                  23
+#define SQLITE_TESTCTRL_SORTER_MMAP             24
+#define SQLITE_TESTCTRL_IMPOSTER                25
+#define SQLITE_TESTCTRL_LAST                    25
+
+/*
+** CAPI3REF: SQLite Runtime Status
+**
+** ^These interfaces are used to retrieve runtime status information
+** about the performance of SQLite, and optionally to reset various
+** highwater marks.  ^The first argument is an integer code for
+** the specific parameter to measure.  ^(Recognized integer codes
+** are of the form [status parameters | SQLITE_STATUS_...].)^
+** ^The current value of the parameter is returned into *pCurrent.
+** ^The highest recorded value is returned in *pHighwater.  ^If the
+** resetFlag is true, then the highest record value is reset after
+** *pHighwater is written.  ^(Some parameters do not record the highest
+** value.  For those parameters
+** nothing is written into *pHighwater and the resetFlag is ignored.)^
+** ^(Other parameters record only the highwater mark and not the current
+** value.  For these latter parameters nothing is written into *pCurrent.)^
+**
+** ^The sqlite3_status() and sqlite3_status64() routines return
+** SQLITE_OK on success and a non-zero [error code] on failure.
+**
+** If either the current value or the highwater mark is too large to
+** be represented by a 32-bit integer, then the values returned by
+** sqlite3_status() are undefined.
+**
+** See also: [sqlite3_db_status()]
+*/
+SQLITE_API int sqlite3_status(int op, int *pCurrent, int *pHighwater, int resetFlag);
+SQLITE_API int sqlite3_status64(
+  int op,
+  sqlite3_int64 *pCurrent,
+  sqlite3_int64 *pHighwater,
+  int resetFlag
+);
+
+
+/*
+** CAPI3REF: Status Parameters
+** KEYWORDS: {status parameters}
+**
+** These integer constants designate various run-time status parameters
+** that can be returned by [sqlite3_status()].
+**
+** <dl>
+** [[SQLITE_STATUS_MEMORY_USED]] ^(<dt>SQLITE_STATUS_MEMORY_USED</dt>
+** <dd>This parameter is the current amount of memory checked out
+** using [sqlite3_malloc()], either directly or indirectly.  The
+** figure includes calls made to [sqlite3_malloc()] by the application
+** and internal memory usage by the SQLite library.  Scratch memory
+** controlled by [SQLITE_CONFIG_SCRATCH] and auxiliary page-cache
+** memory controlled by [SQLITE_CONFIG_PAGECACHE] is not included in
+** this parameter.  The amount returned is the sum of the allocation
+** sizes as reported by the xSize method in [sqlite3_mem_methods].</dd>)^
+**
+** [[SQLITE_STATUS_MALLOC_SIZE]] ^(<dt>SQLITE_STATUS_MALLOC_SIZE</dt>
+** <dd>This parameter records the largest memory allocation request
+** handed to [sqlite3_malloc()] or [sqlite3_realloc()] (or their
+** internal equivalents).  Only the value returned in the
+** *pHighwater parameter to [sqlite3_status()] is of interest.  
+** The value written into the *pCurrent parameter is undefined.</dd>)^
+**
+** [[SQLITE_STATUS_MALLOC_COUNT]] ^(<dt>SQLITE_STATUS_MALLOC_COUNT</dt>
+** <dd>This parameter records the number of separate memory allocations
+** currently checked out.</dd>)^
+**
+** [[SQLITE_STATUS_PAGECACHE_USED]] ^(<dt>SQLITE_STATUS_PAGECACHE_USED</dt>
+** <dd>This parameter returns the number of pages used out of the
+** [pagecache memory allocator] that was configured using 
+** [SQLITE_CONFIG_PAGECACHE].  The
+** value returned is in pages, not in bytes.</dd>)^
+**
+** [[SQLITE_STATUS_PAGECACHE_OVERFLOW]] 
+** ^(<dt>SQLITE_STATUS_PAGECACHE_OVERFLOW</dt>
+** <dd>This parameter returns the number of bytes of page cache
+** allocation which could not be satisfied by the [SQLITE_CONFIG_PAGECACHE]
+** buffer and where forced to overflow to [sqlite3_malloc()].  The
+** returned value includes allocations that overflowed because they
+** where too large (they were larger than the "sz" parameter to
+** [SQLITE_CONFIG_PAGECACHE]) and allocations that overflowed because
+** no space was left in the page cache.</dd>)^
+**
+** [[SQLITE_STATUS_PAGECACHE_SIZE]] ^(<dt>SQLITE_STATUS_PAGECACHE_SIZE</dt>
+** <dd>This parameter records the largest memory allocation request
+** handed to [pagecache memory allocator].  Only the value returned in the
+** *pHighwater parameter to [sqlite3_status()] is of interest.  
+** The value written into the *pCurrent parameter is undefined.</dd>)^
+**
+** [[SQLITE_STATUS_SCRATCH_USED]] ^(<dt>SQLITE_STATUS_SCRATCH_USED</dt>
+** <dd>This parameter returns the number of allocations used out of the
+** [scratch memory allocator] configured using
+** [SQLITE_CONFIG_SCRATCH].  The value returned is in allocations, not
+** in bytes.  Since a single thread may only have one scratch allocation
+** outstanding at time, this parameter also reports the number of threads
+** using scratch memory at the same time.</dd>)^
+**
+** [[SQLITE_STATUS_SCRATCH_OVERFLOW]] ^(<dt>SQLITE_STATUS_SCRATCH_OVERFLOW</dt>
+** <dd>This parameter returns the number of bytes of scratch memory
+** allocation which could not be satisfied by the [SQLITE_CONFIG_SCRATCH]
+** buffer and where forced to overflow to [sqlite3_malloc()].  The values
+** returned include overflows because the requested allocation was too
+** larger (that is, because the requested allocation was larger than the
+** "sz" parameter to [SQLITE_CONFIG_SCRATCH]) and because no scratch buffer
+** slots were available.
+** </dd>)^
+**
+** [[SQLITE_STATUS_SCRATCH_SIZE]] ^(<dt>SQLITE_STATUS_SCRATCH_SIZE</dt>
+** <dd>This parameter records the largest memory allocation request
+** handed to [scratch memory allocator].  Only the value returned in the
+** *pHighwater parameter to [sqlite3_status()] is of interest.  
+** The value written into the *pCurrent parameter is undefined.</dd>)^
+**
+** [[SQLITE_STATUS_PARSER_STACK]] ^(<dt>SQLITE_STATUS_PARSER_STACK</dt>
+** <dd>The *pHighwater parameter records the deepest parser stack. 
+** The *pCurrent value is undefined.  The *pHighwater value is only
+** meaningful if SQLite is compiled with [YYTRACKMAXSTACKDEPTH].</dd>)^
+** </dl>
+**
+** New status parameters may be added from time to time.
+*/
+#define SQLITE_STATUS_MEMORY_USED          0
+#define SQLITE_STATUS_PAGECACHE_USED       1
+#define SQLITE_STATUS_PAGECACHE_OVERFLOW   2
+#define SQLITE_STATUS_SCRATCH_USED         3
+#define SQLITE_STATUS_SCRATCH_OVERFLOW     4
+#define SQLITE_STATUS_MALLOC_SIZE          5
+#define SQLITE_STATUS_PARSER_STACK         6
+#define SQLITE_STATUS_PAGECACHE_SIZE       7
+#define SQLITE_STATUS_SCRATCH_SIZE         8
+#define SQLITE_STATUS_MALLOC_COUNT         9
+
+/*
+** CAPI3REF: Database Connection Status
+** METHOD: sqlite3
+**
+** ^This interface is used to retrieve runtime status information 
+** about a single [database connection].  ^The first argument is the
+** database connection object to be interrogated.  ^The second argument
+** is an integer constant, taken from the set of
+** [SQLITE_DBSTATUS options], that
+** determines the parameter to interrogate.  The set of 
+** [SQLITE_DBSTATUS options] is likely
+** to grow in future releases of SQLite.
+**
+** ^The current value of the requested parameter is written into *pCur
+** and the highest instantaneous value is written into *pHiwtr.  ^If
+** the resetFlg is true, then the highest instantaneous value is
+** reset back down to the current value.
+**
+** ^The sqlite3_db_status() routine returns SQLITE_OK on success and a
+** non-zero [error code] on failure.
+**
+** See also: [sqlite3_status()] and [sqlite3_stmt_status()].
+*/
+SQLITE_API int sqlite3_db_status(sqlite3*, int op, int *pCur, int *pHiwtr, int resetFlg);
+
+/*
+** CAPI3REF: Status Parameters for database connections
+** KEYWORDS: {SQLITE_DBSTATUS options}
+**
+** These constants are the available integer "verbs" that can be passed as
+** the second argument to the [sqlite3_db_status()] interface.
+**
+** New verbs may be added in future releases of SQLite. Existing verbs
+** might be discontinued. Applications should check the return code from
+** [sqlite3_db_status()] to make sure that the call worked.
+** The [sqlite3_db_status()] interface will return a non-zero error code
+** if a discontinued or unsupported verb is invoked.
+**
+** <dl>
+** [[SQLITE_DBSTATUS_LOOKASIDE_USED]] ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_USED</dt>
+** <dd>This parameter returns the number of lookaside memory slots currently
+** checked out.</dd>)^
+**
+** [[SQLITE_DBSTATUS_LOOKASIDE_HIT]] ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_HIT</dt>
+** <dd>This parameter returns the number malloc attempts that were 
+** satisfied using lookaside memory. Only the high-water value is meaningful;
+** the current value is always zero.)^
+**
+** [[SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE]]
+** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE</dt>
+** <dd>This parameter returns the number malloc attempts that might have
+** been satisfied using lookaside memory but failed due to the amount of
+** memory requested being larger than the lookaside slot size.
+** Only the high-water value is meaningful;
+** the current value is always zero.)^
+**
+** [[SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL]]
+** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL</dt>
+** <dd>This parameter returns the number malloc attempts that might have
+** been satisfied using lookaside memory but failed due to all lookaside
+** memory already being in use.
+** Only the high-water value is meaningful;
+** the current value is always zero.)^
+**
+** [[SQLITE_DBSTATUS_CACHE_USED]] ^(<dt>SQLITE_DBSTATUS_CACHE_USED</dt>
+** <dd>This parameter returns the approximate number of bytes of heap
+** memory used by all pager caches associated with the database connection.)^
+** ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_USED is always 0.
+**
+** [[SQLITE_DBSTATUS_CACHE_USED_SHARED]] 
+** ^(<dt>SQLITE_DBSTATUS_CACHE_USED_SHARED</dt>
+** <dd>This parameter is similar to DBSTATUS_CACHE_USED, except that if a
+** pager cache is shared between two or more connections the bytes of heap
+** memory used by that pager cache is divided evenly between the attached
+** connections.)^  In other words, if none of the pager caches associated
+** with the database connection are shared, this request returns the same
+** value as DBSTATUS_CACHE_USED. Or, if one or more or the pager caches are
+** shared, the value returned by this call will be smaller than that returned
+** by DBSTATUS_CACHE_USED. ^The highwater mark associated with
+** SQLITE_DBSTATUS_CACHE_USED_SHARED is always 0.
+**
+** [[SQLITE_DBSTATUS_SCHEMA_USED]] ^(<dt>SQLITE_DBSTATUS_SCHEMA_USED</dt>
+** <dd>This parameter returns the approximate number of bytes of heap
+** memory used to store the schema for all databases associated
+** with the connection - main, temp, and any [ATTACH]-ed databases.)^ 
+** ^The full amount of memory used by the schemas is reported, even if the
+** schema memory is shared with other database connections due to
+** [shared cache mode] being enabled.
+** ^The highwater mark associated with SQLITE_DBSTATUS_SCHEMA_USED is always 0.
+**
+** [[SQLITE_DBSTATUS_STMT_USED]] ^(<dt>SQLITE_DBSTATUS_STMT_USED</dt>
+** <dd>This parameter returns the approximate number of bytes of heap
+** and lookaside memory used by all prepared statements associated with
+** the database connection.)^
+** ^The highwater mark associated with SQLITE_DBSTATUS_STMT_USED is always 0.
+** </dd>
+**
+** [[SQLITE_DBSTATUS_CACHE_HIT]] ^(<dt>SQLITE_DBSTATUS_CACHE_HIT</dt>
+** <dd>This parameter returns the number of pager cache hits that have
+** occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_HIT 
+** is always 0.
+** </dd>
+**
+** [[SQLITE_DBSTATUS_CACHE_MISS]] ^(<dt>SQLITE_DBSTATUS_CACHE_MISS</dt>
+** <dd>This parameter returns the number of pager cache misses that have
+** occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_MISS 
+** is always 0.
+** </dd>
+**
+** [[SQLITE_DBSTATUS_CACHE_WRITE]] ^(<dt>SQLITE_DBSTATUS_CACHE_WRITE</dt>
+** <dd>This parameter returns the number of dirty cache entries that have
+** been written to disk. Specifically, the number of pages written to the
+** wal file in wal mode databases, or the number of pages written to the
+** database file in rollback mode databases. Any pages written as part of
+** transaction rollback or database recovery operations are not included.
+** If an IO or other error occurs while writing a page to disk, the effect
+** on subsequent SQLITE_DBSTATUS_CACHE_WRITE requests is undefined.)^ ^The
+** highwater mark associated with SQLITE_DBSTATUS_CACHE_WRITE is always 0.
+** </dd>
+**
+** [[SQLITE_DBSTATUS_DEFERRED_FKS]] ^(<dt>SQLITE_DBSTATUS_DEFERRED_FKS</dt>
+** <dd>This parameter returns zero for the current value if and only if
+** all foreign key constraints (deferred or immediate) have been
+** resolved.)^  ^The highwater mark is always 0.
+** </dd>
+** </dl>
+*/
+#define SQLITE_DBSTATUS_LOOKASIDE_USED       0
+#define SQLITE_DBSTATUS_CACHE_USED           1
+#define SQLITE_DBSTATUS_SCHEMA_USED          2
+#define SQLITE_DBSTATUS_STMT_USED            3
+#define SQLITE_DBSTATUS_LOOKASIDE_HIT        4
+#define SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE  5
+#define SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL  6
+#define SQLITE_DBSTATUS_CACHE_HIT            7
+#define SQLITE_DBSTATUS_CACHE_MISS           8
+#define SQLITE_DBSTATUS_CACHE_WRITE          9
+#define SQLITE_DBSTATUS_DEFERRED_FKS        10
+#define SQLITE_DBSTATUS_CACHE_USED_SHARED   11
+#define SQLITE_DBSTATUS_MAX                 11   /* Largest defined DBSTATUS */
+
+
+/*
+** CAPI3REF: Prepared Statement Status
+** METHOD: sqlite3_stmt
+**
+** ^(Each prepared statement maintains various
+** [SQLITE_STMTSTATUS counters] that measure the number
+** of times it has performed specific operations.)^  These counters can
+** be used to monitor the performance characteristics of the prepared
+** statements.  For example, if the number of table steps greatly exceeds
+** the number of table searches or result rows, that would tend to indicate
+** that the prepared statement is using a full table scan rather than
+** an index.  
+**
+** ^(This interface is used to retrieve and reset counter values from
+** a [prepared statement].  The first argument is the prepared statement
+** object to be interrogated.  The second argument
+** is an integer code for a specific [SQLITE_STMTSTATUS counter]
+** to be interrogated.)^
+** ^The current value of the requested counter is returned.
+** ^If the resetFlg is true, then the counter is reset to zero after this
+** interface call returns.
+**
+** See also: [sqlite3_status()] and [sqlite3_db_status()].
+*/
+SQLITE_API int sqlite3_stmt_status(sqlite3_stmt*, int op,int resetFlg);
+
+/*
+** CAPI3REF: Status Parameters for prepared statements
+** KEYWORDS: {SQLITE_STMTSTATUS counter} {SQLITE_STMTSTATUS counters}
+**
+** These preprocessor macros define integer codes that name counter
+** values associated with the [sqlite3_stmt_status()] interface.
+** The meanings of the various counters are as follows:
+**
+** <dl>
+** [[SQLITE_STMTSTATUS_FULLSCAN_STEP]] <dt>SQLITE_STMTSTATUS_FULLSCAN_STEP</dt>
+** <dd>^This is the number of times that SQLite has stepped forward in
+** a table as part of a full table scan.  Large numbers for this counter
+** may indicate opportunities for performance improvement through 
+** careful use of indices.</dd>
+**
+** [[SQLITE_STMTSTATUS_SORT]] <dt>SQLITE_STMTSTATUS_SORT</dt>
+** <dd>^This is the number of sort operations that have occurred.
+** A non-zero value in this counter may indicate an opportunity to
+** improvement performance through careful use of indices.</dd>
+**
+** [[SQLITE_STMTSTATUS_AUTOINDEX]] <dt>SQLITE_STMTSTATUS_AUTOINDEX</dt>
+** <dd>^This is the number of rows inserted into transient indices that
+** were created automatically in order to help joins run faster.
+** A non-zero value in this counter may indicate an opportunity to
+** improvement performance by adding permanent indices that do not
+** need to be reinitialized each time the statement is run.</dd>
+**
+** [[SQLITE_STMTSTATUS_VM_STEP]] <dt>SQLITE_STMTSTATUS_VM_STEP</dt>
+** <dd>^This is the number of virtual machine operations executed
+** by the prepared statement if that number is less than or equal
+** to 2147483647.  The number of virtual machine operations can be 
+** used as a proxy for the total work done by the prepared statement.
+** If the number of virtual machine operations exceeds 2147483647
+** then the value returned by this statement status code is undefined.
+** </dd>
+** </dl>
+*/
+#define SQLITE_STMTSTATUS_FULLSCAN_STEP     1
+#define SQLITE_STMTSTATUS_SORT              2
+#define SQLITE_STMTSTATUS_AUTOINDEX         3
+#define SQLITE_STMTSTATUS_VM_STEP           4
+
+/*
+** CAPI3REF: Custom Page Cache Object
+**
+** The sqlite3_pcache type is opaque.  It is implemented by
+** the pluggable module.  The SQLite core has no knowledge of
+** its size or internal structure and never deals with the
+** sqlite3_pcache object except by holding and passing pointers
+** to the object.
+**
+** See [sqlite3_pcache_methods2] for additional information.
+*/
+typedef struct sqlite3_pcache sqlite3_pcache;
+
+/*
+** CAPI3REF: Custom Page Cache Object
+**
+** The sqlite3_pcache_page object represents a single page in the
+** page cache.  The page cache will allocate instances of this
+** object.  Various methods of the page cache use pointers to instances
+** of this object as parameters or as their return value.
+**
+** See [sqlite3_pcache_methods2] for additional information.
+*/
+typedef struct sqlite3_pcache_page sqlite3_pcache_page;
+struct sqlite3_pcache_page {
+  void *pBuf;        /* The content of the page */
+  void *pExtra;      /* Extra information associated with the page */
+};
+
+/*
+** CAPI3REF: Application Defined Page Cache.
+** KEYWORDS: {page cache}
+**
+** ^(The [sqlite3_config]([SQLITE_CONFIG_PCACHE2], ...) interface can
+** register an alternative page cache implementation by passing in an 
+** instance of the sqlite3_pcache_methods2 structure.)^
+** In many applications, most of the heap memory allocated by 
+** SQLite is used for the page cache.
+** By implementing a 
+** custom page cache using this API, an application can better control
+** the amount of memory consumed by SQLite, the way in which 
+** that memory is allocated and released, and the policies used to 
+** determine exactly which parts of a database file are cached and for 
+** how long.
+**
+** The alternative page cache mechanism is an
+** extreme measure that is only needed by the most demanding applications.
+** The built-in page cache is recommended for most uses.
+**
+** ^(The contents of the sqlite3_pcache_methods2 structure are copied to an
+** internal buffer by SQLite within the call to [sqlite3_config].  Hence
+** the application may discard the parameter after the call to
+** [sqlite3_config()] returns.)^
+**
+** [[the xInit() page cache method]]
+** ^(The xInit() method is called once for each effective 
+** call to [sqlite3_initialize()])^
+** (usually only once during the lifetime of the process). ^(The xInit()
+** method is passed a copy of the sqlite3_pcache_methods2.pArg value.)^
+** The intent of the xInit() method is to set up global data structures 
+** required by the custom page cache implementation. 
+** ^(If the xInit() method is NULL, then the 
+** built-in default page cache is used instead of the application defined
+** page cache.)^
+**
+** [[the xShutdown() page cache method]]
+** ^The xShutdown() method is called by [sqlite3_shutdown()].
+** It can be used to clean up 
+** any outstanding resources before process shutdown, if required.
+** ^The xShutdown() method may be NULL.
+**
+** ^SQLite automatically serializes calls to the xInit method,
+** so the xInit method need not be threadsafe.  ^The
+** xShutdown method is only called from [sqlite3_shutdown()] so it does
+** not need to be threadsafe either.  All other methods must be threadsafe
+** in multithreaded applications.
+**
+** ^SQLite will never invoke xInit() more than once without an intervening
+** call to xShutdown().
+**
+** [[the xCreate() page cache methods]]
+** ^SQLite invokes the xCreate() method to construct a new cache instance.
+** SQLite will typically create one cache instance for each open database file,
+** though this is not guaranteed. ^The
+** first parameter, szPage, is the size in bytes of the pages that must
+** be allocated by the cache.  ^szPage will always a power of two.  ^The
+** second parameter szExtra is a number of bytes of extra storage 
+** associated with each page cache entry.  ^The szExtra parameter will
+** a number less than 250.  SQLite will use the
+** extra szExtra bytes on each page to store metadata about the underlying
+** database page on disk.  The value passed into szExtra depends
+** on the SQLite version, the target platform, and how SQLite was compiled.
+** ^The third argument to xCreate(), bPurgeable, is true if the cache being
+** created will be used to cache database pages of a file stored on disk, or
+** false if it is used for an in-memory database. The cache implementation
+** does not have to do anything special based with the value of bPurgeable;
+** it is purely advisory.  ^On a cache where bPurgeable is false, SQLite will
+** never invoke xUnpin() except to deliberately delete a page.
+** ^In other words, calls to xUnpin() on a cache with bPurgeable set to
+** false will always have the "discard" flag set to true.  
+** ^Hence, a cache created with bPurgeable false will
+** never contain any unpinned pages.
+**
+** [[the xCachesize() page cache method]]
+** ^(The xCachesize() method may be called at any time by SQLite to set the
+** suggested maximum cache-size (number of pages stored by) the cache
+** instance passed as the first argument. This is the value configured using
+** the SQLite "[PRAGMA cache_size]" command.)^  As with the bPurgeable
+** parameter, the implementation is not required to do anything with this
+** value; it is advisory only.
+**
+** [[the xPagecount() page cache methods]]
+** The xPagecount() method must return the number of pages currently
+** stored in the cache, both pinned and unpinned.
+** 
+** [[the xFetch() page cache methods]]
+** The xFetch() method locates a page in the cache and returns a pointer to 
+** an sqlite3_pcache_page object associated with that page, or a NULL pointer.
+** The pBuf element of the returned sqlite3_pcache_page object will be a
+** pointer to a buffer of szPage bytes used to store the content of a 
+** single database page.  The pExtra element of sqlite3_pcache_page will be
+** a pointer to the szExtra bytes of extra storage that SQLite has requested
+** for each entry in the page cache.
+**
+** The page to be fetched is determined by the key. ^The minimum key value
+** is 1.  After it has been retrieved using xFetch, the page is considered
+** to be "pinned".
+**
+** If the requested page is already in the page cache, then the page cache
+** implementation must return a pointer to the page buffer with its content
+** intact.  If the requested page is not already in the cache, then the
+** cache implementation should use the value of the createFlag
+** parameter to help it determined what action to take:
+**
+** <table border=1 width=85% align=center>
+** <tr><th> createFlag <th> Behavior when page is not already in cache
+** <tr><td> 0 <td> Do not allocate a new page.  Return NULL.
+** <tr><td> 1 <td> Allocate a new page if it easy and convenient to do so.
+**                 Otherwise return NULL.
+** <tr><td> 2 <td> Make every effort to allocate a new page.  Only return
+**                 NULL if allocating a new page is effectively impossible.
+** </table>
+**
+** ^(SQLite will normally invoke xFetch() with a createFlag of 0 or 1.  SQLite
+** will only use a createFlag of 2 after a prior call with a createFlag of 1
+** failed.)^  In between the to xFetch() calls, SQLite may
+** attempt to unpin one or more cache pages by spilling the content of
+** pinned pages to disk and synching the operating system disk cache.
+**
+** [[the xUnpin() page cache method]]
+** ^xUnpin() is called by SQLite with a pointer to a currently pinned page
+** as its second argument.  If the third parameter, discard, is non-zero,
+** then the page must be evicted from the cache.
+** ^If the discard parameter is
+** zero, then the page may be discarded or retained at the discretion of
+** page cache implementation. ^The page cache implementation
+** may choose to evict unpinned pages at any time.
+**
+** The cache must not perform any reference counting. A single 
+** call to xUnpin() unpins the page regardless of the number of prior calls 
+** to xFetch().
+**
+** [[the xRekey() page cache methods]]
+** The xRekey() method is used to change the key value associated with the
+** page passed as the second argument. If the cache
+** previously contains an entry associated with newKey, it must be
+** discarded. ^Any prior cache entry associated with newKey is guaranteed not
+** to be pinned.
+**
+** When SQLite calls the xTruncate() method, the cache must discard all
+** existing cache entries with page numbers (keys) greater than or equal
+** to the value of the iLimit parameter passed to xTruncate(). If any
+** of these pages are pinned, they are implicitly unpinned, meaning that
+** they can be safely discarded.
+**
+** [[the xDestroy() page cache method]]
+** ^The xDestroy() method is used to delete a cache allocated by xCreate().
+** All resources associated with the specified cache should be freed. ^After
+** calling the xDestroy() method, SQLite considers the [sqlite3_pcache*]
+** handle invalid, and will not use it with any other sqlite3_pcache_methods2
+** functions.
+**
+** [[the xShrink() page cache method]]
+** ^SQLite invokes the xShrink() method when it wants the page cache to
+** free up as much of heap memory as possible.  The page cache implementation
+** is not obligated to free any memory, but well-behaved implementations should
+** do their best.
+*/
+typedef struct sqlite3_pcache_methods2 sqlite3_pcache_methods2;
+struct sqlite3_pcache_methods2 {
+  int iVersion;
+  void *pArg;
+  int (*xInit)(void*);
+  void (*xShutdown)(void*);
+  sqlite3_pcache *(*xCreate)(int szPage, int szExtra, int bPurgeable);
+  void (*xCachesize)(sqlite3_pcache*, int nCachesize);
+  int (*xPagecount)(sqlite3_pcache*);
+  sqlite3_pcache_page *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag);
+  void (*xUnpin)(sqlite3_pcache*, sqlite3_pcache_page*, int discard);
+  void (*xRekey)(sqlite3_pcache*, sqlite3_pcache_page*, 
+      unsigned oldKey, unsigned newKey);
+  void (*xTruncate)(sqlite3_pcache*, unsigned iLimit);
+  void (*xDestroy)(sqlite3_pcache*);
+  void (*xShrink)(sqlite3_pcache*);
+};
+
+/*
+** This is the obsolete pcache_methods object that has now been replaced
+** by sqlite3_pcache_methods2.  This object is not used by SQLite.  It is
+** retained in the header file for backwards compatibility only.
+*/
+typedef struct sqlite3_pcache_methods sqlite3_pcache_methods;
+struct sqlite3_pcache_methods {
+  void *pArg;
+  int (*xInit)(void*);
+  void (*xShutdown)(void*);
+  sqlite3_pcache *(*xCreate)(int szPage, int bPurgeable);
+  void (*xCachesize)(sqlite3_pcache*, int nCachesize);
+  int (*xPagecount)(sqlite3_pcache*);
+  void *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag);
+  void (*xUnpin)(sqlite3_pcache*, void*, int discard);
+  void (*xRekey)(sqlite3_pcache*, void*, unsigned oldKey, unsigned newKey);
+  void (*xTruncate)(sqlite3_pcache*, unsigned iLimit);
+  void (*xDestroy)(sqlite3_pcache*);
+};
+
+
+/*
+** CAPI3REF: Online Backup Object
+**
+** The sqlite3_backup object records state information about an ongoing
+** online backup operation.  ^The sqlite3_backup object is created by
+** a call to [sqlite3_backup_init()] and is destroyed by a call to
+** [sqlite3_backup_finish()].
+**
+** See Also: [Using the SQLite Online Backup API]
+*/
+typedef struct sqlite3_backup sqlite3_backup;
+
+/*
+** CAPI3REF: Online Backup API.
+**
+** The backup API copies the content of one database into another.
+** It is useful either for creating backups of databases or
+** for copying in-memory databases to or from persistent files. 
+**
+** See Also: [Using the SQLite Online Backup API]
+**
+** ^SQLite holds a write transaction open on the destination database file
+** for the duration of the backup operation.
+** ^The source database is read-locked only while it is being read;
+** it is not locked continuously for the entire backup operation.
+** ^Thus, the backup may be performed on a live source database without
+** preventing other database connections from
+** reading or writing to the source database while the backup is underway.
+** 
+** ^(To perform a backup operation: 
+**   <ol>
+**     <li><b>sqlite3_backup_init()</b> is called once to initialize the
+**         backup, 
+**     <li><b>sqlite3_backup_step()</b> is called one or more times to transfer 
+**         the data between the two databases, and finally
+**     <li><b>sqlite3_backup_finish()</b> is called to release all resources 
+**         associated with the backup operation. 
+**   </ol>)^
+** There should be exactly one call to sqlite3_backup_finish() for each
+** successful call to sqlite3_backup_init().
+**
+** [[sqlite3_backup_init()]] <b>sqlite3_backup_init()</b>
+**
+** ^The D and N arguments to sqlite3_backup_init(D,N,S,M) are the 
+** [database connection] associated with the destination database 
+** and the database name, respectively.
+** ^The database name is "main" for the main database, "temp" for the
+** temporary database, or the name specified after the AS keyword in
+** an [ATTACH] statement for an attached database.
+** ^The S and M arguments passed to 
+** sqlite3_backup_init(D,N,S,M) identify the [database connection]
+** and database name of the source database, respectively.
+** ^The source and destination [database connections] (parameters S and D)
+** must be different or else sqlite3_backup_init(D,N,S,M) will fail with
+** an error.
+**
+** ^A call to sqlite3_backup_init() will fail, returning NULL, if 
+** there is already a read or read-write transaction open on the 
+** destination database.
+**
+** ^If an error occurs within sqlite3_backup_init(D,N,S,M), then NULL is
+** returned and an error code and error message are stored in the
+** destination [database connection] D.
+** ^The error code and message for the failed call to sqlite3_backup_init()
+** can be retrieved using the [sqlite3_errcode()], [sqlite3_errmsg()], and/or
+** [sqlite3_errmsg16()] functions.
+** ^A successful call to sqlite3_backup_init() returns a pointer to an
+** [sqlite3_backup] object.
+** ^The [sqlite3_backup] object may be used with the sqlite3_backup_step() and
+** sqlite3_backup_finish() functions to perform the specified backup 
+** operation.
+**
+** [[sqlite3_backup_step()]] <b>sqlite3_backup_step()</b>
+**
+** ^Function sqlite3_backup_step(B,N) will copy up to N pages between 
+** the source and destination databases specified by [sqlite3_backup] object B.
+** ^If N is negative, all remaining source pages are copied. 
+** ^If sqlite3_backup_step(B,N) successfully copies N pages and there
+** are still more pages to be copied, then the function returns [SQLITE_OK].
+** ^If sqlite3_backup_step(B,N) successfully finishes copying all pages
+** from source to destination, then it returns [SQLITE_DONE].
+** ^If an error occurs while running sqlite3_backup_step(B,N),
+** then an [error code] is returned. ^As well as [SQLITE_OK] and
+** [SQLITE_DONE], a call to sqlite3_backup_step() may return [SQLITE_READONLY],
+** [SQLITE_NOMEM], [SQLITE_BUSY], [SQLITE_LOCKED], or an
+** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX] extended error code.
+**
+** ^(The sqlite3_backup_step() might return [SQLITE_READONLY] if
+** <ol>
+** <li> the destination database was opened read-only, or
+** <li> the destination database is using write-ahead-log journaling
+** and the destination and source page sizes differ, or
+** <li> the destination database is an in-memory database and the
+** destination and source page sizes differ.
+** </ol>)^
+**
+** ^If sqlite3_backup_step() cannot obtain a required file-system lock, then
+** the [sqlite3_busy_handler | busy-handler function]
+** is invoked (if one is specified). ^If the 
+** busy-handler returns non-zero before the lock is available, then 
+** [SQLITE_BUSY] is returned to the caller. ^In this case the call to
+** sqlite3_backup_step() can be retried later. ^If the source
+** [database connection]
+** is being used to write to the source database when sqlite3_backup_step()
+** is called, then [SQLITE_LOCKED] is returned immediately. ^Again, in this
+** case the call to sqlite3_backup_step() can be retried later on. ^(If
+** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX], [SQLITE_NOMEM], or
+** [SQLITE_READONLY] is returned, then 
+** there is no point in retrying the call to sqlite3_backup_step(). These 
+** errors are considered fatal.)^  The application must accept 
+** that the backup operation has failed and pass the backup operation handle 
+** to the sqlite3_backup_finish() to release associated resources.
+**
+** ^The first call to sqlite3_backup_step() obtains an exclusive lock
+** on the destination file. ^The exclusive lock is not released until either 
+** sqlite3_backup_finish() is called or the backup operation is complete 
+** and sqlite3_backup_step() returns [SQLITE_DONE].  ^Every call to
+** sqlite3_backup_step() obtains a [shared lock] on the source database that
+** lasts for the duration of the sqlite3_backup_step() call.
+** ^Because the source database is not locked between calls to
+** sqlite3_backup_step(), the source database may be modified mid-way
+** through the backup process.  ^If the source database is modified by an
+** external process or via a database connection other than the one being
+** used by the backup operation, then the backup will be automatically
+** restarted by the next call to sqlite3_backup_step(). ^If the source 
+** database is modified by the using the same database connection as is used
+** by the backup operation, then the backup database is automatically
+** updated at the same time.
+**
+** [[sqlite3_backup_finish()]] <b>sqlite3_backup_finish()</b>
+**
+** When sqlite3_backup_step() has returned [SQLITE_DONE], or when the 
+** application wishes to abandon the backup operation, the application
+** should destroy the [sqlite3_backup] by passing it to sqlite3_backup_finish().
+** ^The sqlite3_backup_finish() interfaces releases all
+** resources associated with the [sqlite3_backup] object. 
+** ^If sqlite3_backup_step() has not yet returned [SQLITE_DONE], then any
+** active write-transaction on the destination database is rolled back.
+** The [sqlite3_backup] object is invalid
+** and may not be used following a call to sqlite3_backup_finish().
+**
+** ^The value returned by sqlite3_backup_finish is [SQLITE_OK] if no
+** sqlite3_backup_step() errors occurred, regardless or whether or not
+** sqlite3_backup_step() completed.
+** ^If an out-of-memory condition or IO error occurred during any prior
+** sqlite3_backup_step() call on the same [sqlite3_backup] object, then
+** sqlite3_backup_finish() returns the corresponding [error code].
+**
+** ^A return of [SQLITE_BUSY] or [SQLITE_LOCKED] from sqlite3_backup_step()
+** is not a permanent error and does not affect the return value of
+** sqlite3_backup_finish().
+**
+** [[sqlite3_backup_remaining()]] [[sqlite3_backup_pagecount()]]
+** <b>sqlite3_backup_remaining() and sqlite3_backup_pagecount()</b>
+**
+** ^The sqlite3_backup_remaining() routine returns the number of pages still
+** to be backed up at the conclusion of the most recent sqlite3_backup_step().
+** ^The sqlite3_backup_pagecount() routine returns the total number of pages
+** in the source database at the conclusion of the most recent
+** sqlite3_backup_step().
+** ^(The values returned by these functions are only updated by
+** sqlite3_backup_step(). If the source database is modified in a way that
+** changes the size of the source database or the number of pages remaining,
+** those changes are not reflected in the output of sqlite3_backup_pagecount()
+** and sqlite3_backup_remaining() until after the next
+** sqlite3_backup_step().)^
+**
+** <b>Concurrent Usage of Database Handles</b>
+**
+** ^The source [database connection] may be used by the application for other
+** purposes while a backup operation is underway or being initialized.
+** ^If SQLite is compiled and configured to support threadsafe database
+** connections, then the source database connection may be used concurrently
+** from within other threads.
+**
+** However, the application must guarantee that the destination 
+** [database connection] is not passed to any other API (by any thread) after 
+** sqlite3_backup_init() is called and before the corresponding call to
+** sqlite3_backup_finish().  SQLite does not currently check to see
+** if the application incorrectly accesses the destination [database connection]
+** and so no error code is reported, but the operations may malfunction
+** nevertheless.  Use of the destination database connection while a
+** backup is in progress might also also cause a mutex deadlock.
+**
+** If running in [shared cache mode], the application must
+** guarantee that the shared cache used by the destination database
+** is not accessed while the backup is running. In practice this means
+** that the application must guarantee that the disk file being 
+** backed up to is not accessed by any connection within the process,
+** not just the specific connection that was passed to sqlite3_backup_init().
+**
+** The [sqlite3_backup] object itself is partially threadsafe. Multiple 
+** threads may safely make multiple concurrent calls to sqlite3_backup_step().
+** However, the sqlite3_backup_remaining() and sqlite3_backup_pagecount()
+** APIs are not strictly speaking threadsafe. If they are invoked at the
+** same time as another thread is invoking sqlite3_backup_step() it is
+** possible that they return invalid values.
+*/
+SQLITE_API sqlite3_backup *sqlite3_backup_init(
+  sqlite3 *pDest,                        /* Destination database handle */
+  const char *zDestName,                 /* Destination database name */
+  sqlite3 *pSource,                      /* Source database handle */
+  const char *zSourceName                /* Source database name */
+);
+SQLITE_API int sqlite3_backup_step(sqlite3_backup *p, int nPage);
+SQLITE_API int sqlite3_backup_finish(sqlite3_backup *p);
+SQLITE_API int sqlite3_backup_remaining(sqlite3_backup *p);
+SQLITE_API int sqlite3_backup_pagecount(sqlite3_backup *p);
+
+/*
+** CAPI3REF: Unlock Notification
+** METHOD: sqlite3
+**
+** ^When running in shared-cache mode, a database operation may fail with
+** an [SQLITE_LOCKED] error if the required locks on the shared-cache or
+** individual tables within the shared-cache cannot be obtained. See
+** [SQLite Shared-Cache Mode] for a description of shared-cache locking. 
+** ^This API may be used to register a callback that SQLite will invoke 
+** when the connection currently holding the required lock relinquishes it.
+** ^This API is only available if the library was compiled with the
+** [SQLITE_ENABLE_UNLOCK_NOTIFY] C-preprocessor symbol defined.
+**
+** See Also: [Using the SQLite Unlock Notification Feature].
+**
+** ^Shared-cache locks are released when a database connection concludes
+** its current transaction, either by committing it or rolling it back. 
+**
+** ^When a connection (known as the blocked connection) fails to obtain a
+** shared-cache lock and SQLITE_LOCKED is returned to the caller, the
+** identity of the database connection (the blocking connection) that
+** has locked the required resource is stored internally. ^After an 
+** application receives an SQLITE_LOCKED error, it may call the
+** sqlite3_unlock_notify() method with the blocked connection handle as 
+** the first argument to register for a callback that will be invoked
+** when the blocking connections current transaction is concluded. ^The
+** callback is invoked from within the [sqlite3_step] or [sqlite3_close]
+** call that concludes the blocking connections transaction.
+**
+** ^(If sqlite3_unlock_notify() is called in a multi-threaded application,
+** there is a chance that the blocking connection will have already
+** concluded its transaction by the time sqlite3_unlock_notify() is invoked.
+** If this happens, then the specified callback is invoked immediately,
+** from within the call to sqlite3_unlock_notify().)^
+**
+** ^If the blocked connection is attempting to obtain a write-lock on a
+** shared-cache table, and more than one other connection currently holds
+** a read-lock on the same table, then SQLite arbitrarily selects one of 
+** the other connections to use as the blocking connection.
+**
+** ^(There may be at most one unlock-notify callback registered by a 
+** blocked connection. If sqlite3_unlock_notify() is called when the
+** blocked connection already has a registered unlock-notify callback,
+** then the new callback replaces the old.)^ ^If sqlite3_unlock_notify() is
+** called with a NULL pointer as its second argument, then any existing
+** unlock-notify callback is canceled. ^The blocked connections 
+** unlock-notify callback may also be canceled by closing the blocked
+** connection using [sqlite3_close()].
+**
+** The unlock-notify callback is not reentrant. If an application invokes
+** any sqlite3_xxx API functions from within an unlock-notify callback, a
+** crash or deadlock may be the result.
+**
+** ^Unless deadlock is detected (see below), sqlite3_unlock_notify() always
+** returns SQLITE_OK.
+**
+** <b>Callback Invocation Details</b>
+**
+** When an unlock-notify callback is registered, the application provides a 
+** single void* pointer that is passed to the callback when it is invoked.
+** However, the signature of the callback function allows SQLite to pass
+** it an array of void* context pointers. The first argument passed to
+** an unlock-notify callback is a pointer to an array of void* pointers,
+** and the second is the number of entries in the array.
+**
+** When a blocking connections transaction is concluded, there may be
+** more than one blocked connection that has registered for an unlock-notify
+** callback. ^If two or more such blocked connections have specified the
+** same callback function, then instead of invoking the callback function
+** multiple times, it is invoked once with the set of void* context pointers
+** specified by the blocked connections bundled together into an array.
+** This gives the application an opportunity to prioritize any actions 
+** related to the set of unblocked database connections.
+**
+** <b>Deadlock Detection</b>
+**
+** Assuming that after registering for an unlock-notify callback a 
+** database waits for the callback to be issued before taking any further
+** action (a reasonable assumption), then using this API may cause the
+** application to deadlock. For example, if connection X is waiting for
+** connection Y's transaction to be concluded, and similarly connection
+** Y is waiting on connection X's transaction, then neither connection
+** will proceed and the system may remain deadlocked indefinitely.
+**
+** To avoid this scenario, the sqlite3_unlock_notify() performs deadlock
+** detection. ^If a given call to sqlite3_unlock_notify() would put the
+** system in a deadlocked state, then SQLITE_LOCKED is returned and no
+** unlock-notify callback is registered. The system is said to be in
+** a deadlocked state if connection A has registered for an unlock-notify
+** callback on the conclusion of connection B's transaction, and connection
+** B has itself registered for an unlock-notify callback when connection
+** A's transaction is concluded. ^Indirect deadlock is also detected, so
+** the system is also considered to be deadlocked if connection B has
+** registered for an unlock-notify callback on the conclusion of connection
+** C's transaction, where connection C is waiting on connection A. ^Any
+** number of levels of indirection are allowed.
+**
+** <b>The "DROP TABLE" Exception</b>
+**
+** When a call to [sqlite3_step()] returns SQLITE_LOCKED, it is almost 
+** always appropriate to call sqlite3_unlock_notify(). There is however,
+** one exception. When executing a "DROP TABLE" or "DROP INDEX" statement,
+** SQLite checks if there are any currently executing SELECT statements
+** that belong to the same connection. If there are, SQLITE_LOCKED is
+** returned. In this case there is no "blocking connection", so invoking
+** sqlite3_unlock_notify() results in the unlock-notify callback being
+** invoked immediately. If the application then re-attempts the "DROP TABLE"
+** or "DROP INDEX" query, an infinite loop might be the result.
+**
+** One way around this problem is to check the extended error code returned
+** by an sqlite3_step() call. ^(If there is a blocking connection, then the
+** extended error code is set to SQLITE_LOCKED_SHAREDCACHE. Otherwise, in
+** the special "DROP TABLE/INDEX" case, the extended error code is just 
+** SQLITE_LOCKED.)^
+*/
+SQLITE_API int sqlite3_unlock_notify(
+  sqlite3 *pBlocked,                          /* Waiting connection */
+  void (*xNotify)(void **apArg, int nArg),    /* Callback function to invoke */
+  void *pNotifyArg                            /* Argument to pass to xNotify */
+);
+
+
+/*
+** CAPI3REF: String Comparison
+**
+** ^The [sqlite3_stricmp()] and [sqlite3_strnicmp()] APIs allow applications
+** and extensions to compare the contents of two buffers containing UTF-8
+** strings in a case-independent fashion, using the same definition of "case
+** independence" that SQLite uses internally when comparing identifiers.
+*/
+SQLITE_API int sqlite3_stricmp(const char *, const char *);
+SQLITE_API int sqlite3_strnicmp(const char *, const char *, int);
+
+/*
+** CAPI3REF: String Globbing
+*
+** ^The [sqlite3_strglob(P,X)] interface returns zero if and only if
+** string X matches the [GLOB] pattern P.
+** ^The definition of [GLOB] pattern matching used in
+** [sqlite3_strglob(P,X)] is the same as for the "X GLOB P" operator in the
+** SQL dialect understood by SQLite.  ^The [sqlite3_strglob(P,X)] function
+** is case sensitive.
+**
+** Note that this routine returns zero on a match and non-zero if the strings
+** do not match, the same as [sqlite3_stricmp()] and [sqlite3_strnicmp()].
+**
+** See also: [sqlite3_strlike()].
+*/
+SQLITE_API int sqlite3_strglob(const char *zGlob, const char *zStr);
+
+/*
+** CAPI3REF: String LIKE Matching
+*
+** ^The [sqlite3_strlike(P,X,E)] interface returns zero if and only if
+** string X matches the [LIKE] pattern P with escape character E.
+** ^The definition of [LIKE] pattern matching used in
+** [sqlite3_strlike(P,X,E)] is the same as for the "X LIKE P ESCAPE E"
+** operator in the SQL dialect understood by SQLite.  ^For "X LIKE P" without
+** the ESCAPE clause, set the E parameter of [sqlite3_strlike(P,X,E)] to 0.
+** ^As with the LIKE operator, the [sqlite3_strlike(P,X,E)] function is case
+** insensitive - equivalent upper and lower case ASCII characters match
+** one another.
+**
+** ^The [sqlite3_strlike(P,X,E)] function matches Unicode characters, though
+** only ASCII characters are case folded.
+**
+** Note that this routine returns zero on a match and non-zero if the strings
+** do not match, the same as [sqlite3_stricmp()] and [sqlite3_strnicmp()].
+**
+** See also: [sqlite3_strglob()].
+*/
+SQLITE_API int sqlite3_strlike(const char *zGlob, const char *zStr, unsigned int cEsc);
+
+/*
+** CAPI3REF: Error Logging Interface
+**
+** ^The [sqlite3_log()] interface writes a message into the [error log]
+** established by the [SQLITE_CONFIG_LOG] option to [sqlite3_config()].
+** ^If logging is enabled, the zFormat string and subsequent arguments are
+** used with [sqlite3_snprintf()] to generate the final output string.
+**
+** The sqlite3_log() interface is intended for use by extensions such as
+** virtual tables, collating functions, and SQL functions.  While there is
+** nothing to prevent an application from calling sqlite3_log(), doing so
+** is considered bad form.
+**
+** The zFormat string must not be NULL.
+**
+** To avoid deadlocks and other threading problems, the sqlite3_log() routine
+** will not use dynamically allocated memory.  The log message is stored in
+** a fixed-length buffer on the stack.  If the log message is longer than
+** a few hundred characters, it will be truncated to the length of the
+** buffer.
+*/
+SQLITE_API void sqlite3_log(int iErrCode, const char *zFormat, ...);
+
+/*
+** CAPI3REF: Write-Ahead Log Commit Hook
+** METHOD: sqlite3
+**
+** ^The [sqlite3_wal_hook()] function is used to register a callback that
+** is invoked each time data is committed to a database in wal mode.
+**
+** ^(The callback is invoked by SQLite after the commit has taken place and 
+** the associated write-lock on the database released)^, so the implementation 
+** may read, write or [checkpoint] the database as required.
+**
+** ^The first parameter passed to the callback function when it is invoked
+** is a copy of the third parameter passed to sqlite3_wal_hook() when
+** registering the callback. ^The second is a copy of the database handle.
+** ^The third parameter is the name of the database that was written to -
+** either "main" or the name of an [ATTACH]-ed database. ^The fourth parameter
+** is the number of pages currently in the write-ahead log file,
+** including those that were just committed.
+**
+** The callback function should normally return [SQLITE_OK].  ^If an error
+** code is returned, that error will propagate back up through the
+** SQLite code base to cause the statement that provoked the callback
+** to report an error, though the commit will have still occurred. If the
+** callback returns [SQLITE_ROW] or [SQLITE_DONE], or if it returns a value
+** that does not correspond to any valid SQLite error code, the results
+** are undefined.
+**
+** A single database handle may have at most a single write-ahead log callback 
+** registered at one time. ^Calling [sqlite3_wal_hook()] replaces any
+** previously registered write-ahead log callback. ^Note that the
+** [sqlite3_wal_autocheckpoint()] interface and the
+** [wal_autocheckpoint pragma] both invoke [sqlite3_wal_hook()] and will
+** overwrite any prior [sqlite3_wal_hook()] settings.
+*/
+SQLITE_API void *sqlite3_wal_hook(
+  sqlite3*, 
+  int(*)(void *,sqlite3*,const char*,int),
+  void*
+);
+
+/*
+** CAPI3REF: Configure an auto-checkpoint
+** METHOD: sqlite3
+**
+** ^The [sqlite3_wal_autocheckpoint(D,N)] is a wrapper around
+** [sqlite3_wal_hook()] that causes any database on [database connection] D
+** to automatically [checkpoint]
+** after committing a transaction if there are N or
+** more frames in the [write-ahead log] file.  ^Passing zero or 
+** a negative value as the nFrame parameter disables automatic
+** checkpoints entirely.
+**
+** ^The callback registered by this function replaces any existing callback
+** registered using [sqlite3_wal_hook()].  ^Likewise, registering a callback
+** using [sqlite3_wal_hook()] disables the automatic checkpoint mechanism
+** configured by this function.
+**
+** ^The [wal_autocheckpoint pragma] can be used to invoke this interface
+** from SQL.
+**
+** ^Checkpoints initiated by this mechanism are
+** [sqlite3_wal_checkpoint_v2|PASSIVE].
+**
+** ^Every new [database connection] defaults to having the auto-checkpoint
+** enabled with a threshold of 1000 or [SQLITE_DEFAULT_WAL_AUTOCHECKPOINT]
+** pages.  The use of this interface
+** is only necessary if the default setting is found to be suboptimal
+** for a particular application.
+*/
+SQLITE_API int sqlite3_wal_autocheckpoint(sqlite3 *db, int N);
+
+/*
+** CAPI3REF: Checkpoint a database
+** METHOD: sqlite3
+**
+** ^(The sqlite3_wal_checkpoint(D,X) is equivalent to
+** [sqlite3_wal_checkpoint_v2](D,X,[SQLITE_CHECKPOINT_PASSIVE],0,0).)^
+**
+** In brief, sqlite3_wal_checkpoint(D,X) causes the content in the 
+** [write-ahead log] for database X on [database connection] D to be
+** transferred into the database file and for the write-ahead log to
+** be reset.  See the [checkpointing] documentation for addition
+** information.
+**
+** This interface used to be the only way to cause a checkpoint to
+** occur.  But then the newer and more powerful [sqlite3_wal_checkpoint_v2()]
+** interface was added.  This interface is retained for backwards
+** compatibility and as a convenience for applications that need to manually
+** start a callback but which do not need the full power (and corresponding
+** complication) of [sqlite3_wal_checkpoint_v2()].
+*/
+SQLITE_API int sqlite3_wal_checkpoint(sqlite3 *db, const char *zDb);
+
+/*
+** CAPI3REF: Checkpoint a database
+** METHOD: sqlite3
+**
+** ^(The sqlite3_wal_checkpoint_v2(D,X,M,L,C) interface runs a checkpoint
+** operation on database X of [database connection] D in mode M.  Status
+** information is written back into integers pointed to by L and C.)^
+** ^(The M parameter must be a valid [checkpoint mode]:)^
+**
+** <dl>
+** <dt>SQLITE_CHECKPOINT_PASSIVE<dd>
+**   ^Checkpoint as many frames as possible without waiting for any database 
+**   readers or writers to finish, then sync the database file if all frames 
+**   in the log were checkpointed. ^The [busy-handler callback]
+**   is never invoked in the SQLITE_CHECKPOINT_PASSIVE mode.  
+**   ^On the other hand, passive mode might leave the checkpoint unfinished
+**   if there are concurrent readers or writers.
+**
+** <dt>SQLITE_CHECKPOINT_FULL<dd>
+**   ^This mode blocks (it invokes the
+**   [sqlite3_busy_handler|busy-handler callback]) until there is no
+**   database writer and all readers are reading from the most recent database
+**   snapshot. ^It then checkpoints all frames in the log file and syncs the
+**   database file. ^This mode blocks new database writers while it is pending,
+**   but new database readers are allowed to continue unimpeded.
+**
+** <dt>SQLITE_CHECKPOINT_RESTART<dd>
+**   ^This mode works the same way as SQLITE_CHECKPOINT_FULL with the addition
+**   that after checkpointing the log file it blocks (calls the 
+**   [busy-handler callback])
+**   until all readers are reading from the database file only. ^This ensures 
+**   that the next writer will restart the log file from the beginning.
+**   ^Like SQLITE_CHECKPOINT_FULL, this mode blocks new
+**   database writer attempts while it is pending, but does not impede readers.
+**
+** <dt>SQLITE_CHECKPOINT_TRUNCATE<dd>
+**   ^This mode works the same way as SQLITE_CHECKPOINT_RESTART with the
+**   addition that it also truncates the log file to zero bytes just prior
+**   to a successful return.
+** </dl>
+**
+** ^If pnLog is not NULL, then *pnLog is set to the total number of frames in
+** the log file or to -1 if the checkpoint could not run because
+** of an error or because the database is not in [WAL mode]. ^If pnCkpt is not
+** NULL,then *pnCkpt is set to the total number of checkpointed frames in the
+** log file (including any that were already checkpointed before the function
+** was called) or to -1 if the checkpoint could not run due to an error or
+** because the database is not in WAL mode. ^Note that upon successful
+** completion of an SQLITE_CHECKPOINT_TRUNCATE, the log file will have been
+** truncated to zero bytes and so both *pnLog and *pnCkpt will be set to zero.
+**
+** ^All calls obtain an exclusive "checkpoint" lock on the database file. ^If
+** any other process is running a checkpoint operation at the same time, the 
+** lock cannot be obtained and SQLITE_BUSY is returned. ^Even if there is a 
+** busy-handler configured, it will not be invoked in this case.
+**
+** ^The SQLITE_CHECKPOINT_FULL, RESTART and TRUNCATE modes also obtain the 
+** exclusive "writer" lock on the database file. ^If the writer lock cannot be
+** obtained immediately, and a busy-handler is configured, it is invoked and
+** the writer lock retried until either the busy-handler returns 0 or the lock
+** is successfully obtained. ^The busy-handler is also invoked while waiting for
+** database readers as described above. ^If the busy-handler returns 0 before
+** the writer lock is obtained or while waiting for database readers, the
+** checkpoint operation proceeds from that point in the same way as 
+** SQLITE_CHECKPOINT_PASSIVE - checkpointing as many frames as possible 
+** without blocking any further. ^SQLITE_BUSY is returned in this case.
+**
+** ^If parameter zDb is NULL or points to a zero length string, then the
+** specified operation is attempted on all WAL databases [attached] to 
+** [database connection] db.  In this case the
+** values written to output parameters *pnLog and *pnCkpt are undefined. ^If 
+** an SQLITE_BUSY error is encountered when processing one or more of the 
+** attached WAL databases, the operation is still attempted on any remaining 
+** attached databases and SQLITE_BUSY is returned at the end. ^If any other 
+** error occurs while processing an attached database, processing is abandoned 
+** and the error code is returned to the caller immediately. ^If no error 
+** (SQLITE_BUSY or otherwise) is encountered while processing the attached 
+** databases, SQLITE_OK is returned.
+**
+** ^If database zDb is the name of an attached database that is not in WAL
+** mode, SQLITE_OK is returned and both *pnLog and *pnCkpt set to -1. ^If
+** zDb is not NULL (or a zero length string) and is not the name of any
+** attached database, SQLITE_ERROR is returned to the caller.
+**
+** ^Unless it returns SQLITE_MISUSE,
+** the sqlite3_wal_checkpoint_v2() interface
+** sets the error information that is queried by
+** [sqlite3_errcode()] and [sqlite3_errmsg()].
+**
+** ^The [PRAGMA wal_checkpoint] command can be used to invoke this interface
+** from SQL.
+*/
+SQLITE_API int sqlite3_wal_checkpoint_v2(
+  sqlite3 *db,                    /* Database handle */
+  const char *zDb,                /* Name of attached database (or NULL) */
+  int eMode,                      /* SQLITE_CHECKPOINT_* value */
+  int *pnLog,                     /* OUT: Size of WAL log in frames */
+  int *pnCkpt                     /* OUT: Total number of frames checkpointed */
+);
+
+/*
+** CAPI3REF: Checkpoint Mode Values
+** KEYWORDS: {checkpoint mode}
+**
+** These constants define all valid values for the "checkpoint mode" passed
+** as the third parameter to the [sqlite3_wal_checkpoint_v2()] interface.
+** See the [sqlite3_wal_checkpoint_v2()] documentation for details on the
+** meaning of each of these checkpoint modes.
+*/
+#define SQLITE_CHECKPOINT_PASSIVE  0  /* Do as much as possible w/o blocking */
+#define SQLITE_CHECKPOINT_FULL     1  /* Wait for writers, then checkpoint */
+#define SQLITE_CHECKPOINT_RESTART  2  /* Like FULL but wait for for readers */
+#define SQLITE_CHECKPOINT_TRUNCATE 3  /* Like RESTART but also truncate WAL */
+
+/*
+** CAPI3REF: Virtual Table Interface Configuration
+**
+** This function may be called by either the [xConnect] or [xCreate] method
+** of a [virtual table] implementation to configure
+** various facets of the virtual table interface.
+**
+** If this interface is invoked outside the context of an xConnect or
+** xCreate virtual table method then the behavior is undefined.
+**
+** At present, there is only one option that may be configured using
+** this function. (See [SQLITE_VTAB_CONSTRAINT_SUPPORT].)  Further options
+** may be added in the future.
+*/
+SQLITE_API int sqlite3_vtab_config(sqlite3*, int op, ...);
+
+/*
+** CAPI3REF: Virtual Table Configuration Options
+**
+** These macros define the various options to the
+** [sqlite3_vtab_config()] interface that [virtual table] implementations
+** can use to customize and optimize their behavior.
+**
+** <dl>
+** <dt>SQLITE_VTAB_CONSTRAINT_SUPPORT
+** <dd>Calls of the form
+** [sqlite3_vtab_config](db,SQLITE_VTAB_CONSTRAINT_SUPPORT,X) are supported,
+** where X is an integer.  If X is zero, then the [virtual table] whose
+** [xCreate] or [xConnect] method invoked [sqlite3_vtab_config()] does not
+** support constraints.  In this configuration (which is the default) if
+** a call to the [xUpdate] method returns [SQLITE_CONSTRAINT], then the entire
+** statement is rolled back as if [ON CONFLICT | OR ABORT] had been
+** specified as part of the users SQL statement, regardless of the actual
+** ON CONFLICT mode specified.
+**
+** If X is non-zero, then the virtual table implementation guarantees
+** that if [xUpdate] returns [SQLITE_CONSTRAINT], it will do so before
+** any modifications to internal or persistent data structures have been made.
+** If the [ON CONFLICT] mode is ABORT, FAIL, IGNORE or ROLLBACK, SQLite 
+** is able to roll back a statement or database transaction, and abandon
+** or continue processing the current SQL statement as appropriate. 
+** If the ON CONFLICT mode is REPLACE and the [xUpdate] method returns
+** [SQLITE_CONSTRAINT], SQLite handles this as if the ON CONFLICT mode
+** had been ABORT.
+**
+** Virtual table implementations that are required to handle OR REPLACE
+** must do so within the [xUpdate] method. If a call to the 
+** [sqlite3_vtab_on_conflict()] function indicates that the current ON 
+** CONFLICT policy is REPLACE, the virtual table implementation should 
+** silently replace the appropriate rows within the xUpdate callback and
+** return SQLITE_OK. Or, if this is not possible, it may return
+** SQLITE_CONSTRAINT, in which case SQLite falls back to OR ABORT 
+** constraint handling.
+** </dl>
+*/
+#define SQLITE_VTAB_CONSTRAINT_SUPPORT 1
+
+/*
+** CAPI3REF: Determine The Virtual Table Conflict Policy
+**
+** This function may only be called from within a call to the [xUpdate] method
+** of a [virtual table] implementation for an INSERT or UPDATE operation. ^The
+** value returned is one of [SQLITE_ROLLBACK], [SQLITE_IGNORE], [SQLITE_FAIL],
+** [SQLITE_ABORT], or [SQLITE_REPLACE], according to the [ON CONFLICT] mode
+** of the SQL statement that triggered the call to the [xUpdate] method of the
+** [virtual table].
+*/
+SQLITE_API int sqlite3_vtab_on_conflict(sqlite3 *);
+
+/*
+** CAPI3REF: Conflict resolution modes
+** KEYWORDS: {conflict resolution mode}
+**
+** These constants are returned by [sqlite3_vtab_on_conflict()] to
+** inform a [virtual table] implementation what the [ON CONFLICT] mode
+** is for the SQL statement being evaluated.
+**
+** Note that the [SQLITE_IGNORE] constant is also used as a potential
+** return value from the [sqlite3_set_authorizer()] callback and that
+** [SQLITE_ABORT] is also a [result code].
+*/
+#define SQLITE_ROLLBACK 1
+/* #define SQLITE_IGNORE 2 // Also used by sqlite3_authorizer() callback */
+#define SQLITE_FAIL     3
+/* #define SQLITE_ABORT 4  // Also an error code */
+#define SQLITE_REPLACE  5
+
+/*
+** CAPI3REF: Prepared Statement Scan Status Opcodes
+** KEYWORDS: {scanstatus options}
+**
+** The following constants can be used for the T parameter to the
+** [sqlite3_stmt_scanstatus(S,X,T,V)] interface.  Each constant designates a
+** different metric for sqlite3_stmt_scanstatus() to return.
+**
+** When the value returned to V is a string, space to hold that string is
+** managed by the prepared statement S and will be automatically freed when
+** S is finalized.
+**
+** <dl>
+** [[SQLITE_SCANSTAT_NLOOP]] <dt>SQLITE_SCANSTAT_NLOOP</dt>
+** <dd>^The [sqlite3_int64] variable pointed to by the T parameter will be
+** set to the total number of times that the X-th loop has run.</dd>
+**
+** [[SQLITE_SCANSTAT_NVISIT]] <dt>SQLITE_SCANSTAT_NVISIT</dt>
+** <dd>^The [sqlite3_int64] variable pointed to by the T parameter will be set
+** to the total number of rows examined by all iterations of the X-th loop.</dd>
+**
+** [[SQLITE_SCANSTAT_EST]] <dt>SQLITE_SCANSTAT_EST</dt>
+** <dd>^The "double" variable pointed to by the T parameter will be set to the
+** query planner's estimate for the average number of rows output from each
+** iteration of the X-th loop.  If the query planner's estimates was accurate,
+** then this value will approximate the quotient NVISIT/NLOOP and the
+** product of this value for all prior loops with the same SELECTID will
+** be the NLOOP value for the current loop.
+**
+** [[SQLITE_SCANSTAT_NAME]] <dt>SQLITE_SCANSTAT_NAME</dt>
+** <dd>^The "const char *" variable pointed to by the T parameter will be set
+** to a zero-terminated UTF-8 string containing the name of the index or table
+** used for the X-th loop.
+**
+** [[SQLITE_SCANSTAT_EXPLAIN]] <dt>SQLITE_SCANSTAT_EXPLAIN</dt>
+** <dd>^The "const char *" variable pointed to by the T parameter will be set
+** to a zero-terminated UTF-8 string containing the [EXPLAIN QUERY PLAN]
+** description for the X-th loop.
+**
+** [[SQLITE_SCANSTAT_SELECTID]] <dt>SQLITE_SCANSTAT_SELECT</dt>
+** <dd>^The "int" variable pointed to by the T parameter will be set to the
+** "select-id" for the X-th loop.  The select-id identifies which query or
+** subquery the loop is part of.  The main query has a select-id of zero.
+** The select-id is the same value as is output in the first column
+** of an [EXPLAIN QUERY PLAN] query.
+** </dl>
+*/
+#define SQLITE_SCANSTAT_NLOOP    0
+#define SQLITE_SCANSTAT_NVISIT   1
+#define SQLITE_SCANSTAT_EST      2
+#define SQLITE_SCANSTAT_NAME     3
+#define SQLITE_SCANSTAT_EXPLAIN  4
+#define SQLITE_SCANSTAT_SELECTID 5
+
+/*
+** CAPI3REF: Prepared Statement Scan Status
+** METHOD: sqlite3_stmt
+**
+** This interface returns information about the predicted and measured
+** performance for pStmt.  Advanced applications can use this
+** interface to compare the predicted and the measured performance and
+** issue warnings and/or rerun [ANALYZE] if discrepancies are found.
+**
+** Since this interface is expected to be rarely used, it is only
+** available if SQLite is compiled using the [SQLITE_ENABLE_STMT_SCANSTATUS]
+** compile-time option.
+**
+** The "iScanStatusOp" parameter determines which status information to return.
+** The "iScanStatusOp" must be one of the [scanstatus options] or the behavior
+** of this interface is undefined.
+** ^The requested measurement is written into a variable pointed to by
+** the "pOut" parameter.
+** Parameter "idx" identifies the specific loop to retrieve statistics for.
+** Loops are numbered starting from zero. ^If idx is out of range - less than
+** zero or greater than or equal to the total number of loops used to implement
+** the statement - a non-zero value is returned and the variable that pOut
+** points to is unchanged.
+**
+** ^Statistics might not be available for all loops in all statements. ^In cases
+** where there exist loops with no available statistics, this function behaves
+** as if the loop did not exist - it returns non-zero and leave the variable
+** that pOut points to unchanged.
+**
+** See also: [sqlite3_stmt_scanstatus_reset()]
+*/
+SQLITE_API int sqlite3_stmt_scanstatus(
+  sqlite3_stmt *pStmt,      /* Prepared statement for which info desired */
+  int idx,                  /* Index of loop to report on */
+  int iScanStatusOp,        /* Information desired.  SQLITE_SCANSTAT_* */
+  void *pOut                /* Result written here */
+);     
+
+/*
+** CAPI3REF: Zero Scan-Status Counters
+** METHOD: sqlite3_stmt
+**
+** ^Zero all [sqlite3_stmt_scanstatus()] related event counters.
+**
+** This API is only available if the library is built with pre-processor
+** symbol [SQLITE_ENABLE_STMT_SCANSTATUS] defined.
+*/
+SQLITE_API void sqlite3_stmt_scanstatus_reset(sqlite3_stmt*);
+
+/*
+** CAPI3REF: Flush caches to disk mid-transaction
+**
+** ^If a write-transaction is open on [database connection] D when the
+** [sqlite3_db_cacheflush(D)] interface invoked, any dirty
+** pages in the pager-cache that are not currently in use are written out 
+** to disk. A dirty page may be in use if a database cursor created by an
+** active SQL statement is reading from it, or if it is page 1 of a database
+** file (page 1 is always "in use").  ^The [sqlite3_db_cacheflush(D)]
+** interface flushes caches for all schemas - "main", "temp", and
+** any [attached] databases.
+**
+** ^If this function needs to obtain extra database locks before dirty pages 
+** can be flushed to disk, it does so. ^If those locks cannot be obtained 
+** immediately and there is a busy-handler callback configured, it is invoked
+** in the usual manner. ^If the required lock still cannot be obtained, then
+** the database is skipped and an attempt made to flush any dirty pages
+** belonging to the next (if any) database. ^If any databases are skipped
+** because locks cannot be obtained, but no other error occurs, this
+** function returns SQLITE_BUSY.
+**
+** ^If any other error occurs while flushing dirty pages to disk (for
+** example an IO error or out-of-memory condition), then processing is
+** abandoned and an SQLite [error code] is returned to the caller immediately.
+**
+** ^Otherwise, if no error occurs, [sqlite3_db_cacheflush()] returns SQLITE_OK.
+**
+** ^This function does not set the database handle error code or message
+** returned by the [sqlite3_errcode()] and [sqlite3_errmsg()] functions.
+*/
+SQLITE_API int sqlite3_db_cacheflush(sqlite3*);
+
+/*
+** CAPI3REF: The pre-update hook.
+**
+** ^These interfaces are only available if SQLite is compiled using the
+** [SQLITE_ENABLE_PREUPDATE_HOOK] compile-time option.
+**
+** ^The [sqlite3_preupdate_hook()] interface registers a callback function
+** that is invoked prior to each [INSERT], [UPDATE], and [DELETE] operation
+** on a [rowid table].
+** ^At most one preupdate hook may be registered at a time on a single
+** [database connection]; each call to [sqlite3_preupdate_hook()] overrides
+** the previous setting.
+** ^The preupdate hook is disabled by invoking [sqlite3_preupdate_hook()]
+** with a NULL pointer as the second parameter.
+** ^The third parameter to [sqlite3_preupdate_hook()] is passed through as
+** the first parameter to callbacks.
+**
+** ^The preupdate hook only fires for changes to [rowid tables]; the preupdate
+** hook is not invoked for changes to [virtual tables] or [WITHOUT ROWID]
+** tables.
+**
+** ^The second parameter to the preupdate callback is a pointer to
+** the [database connection] that registered the preupdate hook.
+** ^The third parameter to the preupdate callback is one of the constants
+** [SQLITE_INSERT], [SQLITE_DELETE], or [SQLITE_UPDATE] to identify the
+** kind of update operation that is about to occur.
+** ^(The fourth parameter to the preupdate callback is the name of the
+** database within the database connection that is being modified.  This
+** will be "main" for the main database or "temp" for TEMP tables or 
+** the name given after the AS keyword in the [ATTACH] statement for attached
+** databases.)^
+** ^The fifth parameter to the preupdate callback is the name of the
+** table that is being modified.
+** ^The sixth parameter to the preupdate callback is the initial [rowid] of the
+** row being changes for SQLITE_UPDATE and SQLITE_DELETE changes and is
+** undefined for SQLITE_INSERT changes.
+** ^The seventh parameter to the preupdate callback is the final [rowid] of
+** the row being changed for SQLITE_UPDATE and SQLITE_INSERT changes and is
+** undefined for SQLITE_DELETE changes.
+**
+** The [sqlite3_preupdate_old()], [sqlite3_preupdate_new()],
+** [sqlite3_preupdate_count()], and [sqlite3_preupdate_depth()] interfaces
+** provide additional information about a preupdate event. These routines
+** may only be called from within a preupdate callback.  Invoking any of
+** these routines from outside of a preupdate callback or with a
+** [database connection] pointer that is different from the one supplied
+** to the preupdate callback results in undefined and probably undesirable
+** behavior.
+**
+** ^The [sqlite3_preupdate_count(D)] interface returns the number of columns
+** in the row that is being inserted, updated, or deleted.
+**
+** ^The [sqlite3_preupdate_old(D,N,P)] interface writes into P a pointer to
+** a [protected sqlite3_value] that contains the value of the Nth column of
+** the table row before it is updated.  The N parameter must be between 0
+** and one less than the number of columns or the behavior will be
+** undefined. This must only be used within SQLITE_UPDATE and SQLITE_DELETE
+** preupdate callbacks; if it is used by an SQLITE_INSERT callback then the
+** behavior is undefined.  The [sqlite3_value] that P points to
+** will be destroyed when the preupdate callback returns.
+**
+** ^The [sqlite3_preupdate_new(D,N,P)] interface writes into P a pointer to
+** a [protected sqlite3_value] that contains the value of the Nth column of
+** the table row after it is updated.  The N parameter must be between 0
+** and one less than the number of columns or the behavior will be
+** undefined. This must only be used within SQLITE_INSERT and SQLITE_UPDATE
+** preupdate callbacks; if it is used by an SQLITE_DELETE callback then the
+** behavior is undefined.  The [sqlite3_value] that P points to
+** will be destroyed when the preupdate callback returns.
+**
+** ^The [sqlite3_preupdate_depth(D)] interface returns 0 if the preupdate
+** callback was invoked as a result of a direct insert, update, or delete
+** operation; or 1 for inserts, updates, or deletes invoked by top-level 
+** triggers; or 2 for changes resulting from triggers called by top-level
+** triggers; and so forth.
+**
+** See also:  [sqlite3_update_hook()]
+*/
+SQLITE_API SQLITE_EXPERIMENTAL void *sqlite3_preupdate_hook(
+  sqlite3 *db,
+  void(*xPreUpdate)(
+    void *pCtx,                   /* Copy of third arg to preupdate_hook() */
+    sqlite3 *db,                  /* Database handle */
+    int op,                       /* SQLITE_UPDATE, DELETE or INSERT */
+    char const *zDb,              /* Database name */
+    char const *zName,            /* Table name */
+    sqlite3_int64 iKey1,          /* Rowid of row about to be deleted/updated */
+    sqlite3_int64 iKey2           /* New rowid value (for a rowid UPDATE) */
+  ),
+  void*
+);
+SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_preupdate_old(sqlite3 *, int, sqlite3_value **);
+SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_preupdate_count(sqlite3 *);
+SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_preupdate_depth(sqlite3 *);
+SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_preupdate_new(sqlite3 *, int, sqlite3_value **);
+
+/*
+** CAPI3REF: Low-level system error code
+**
+** ^Attempt to return the underlying operating system error code or error
+** number that caused the most recent I/O error or failure to open a file.
+** The return value is OS-dependent.  For example, on unix systems, after
+** [sqlite3_open_v2()] returns [SQLITE_CANTOPEN], this interface could be
+** called to get back the underlying "errno" that caused the problem, such
+** as ENOSPC, EAUTH, EISDIR, and so forth.  
+*/
+SQLITE_API int sqlite3_system_errno(sqlite3*);
+
+/*
+** CAPI3REF: Database Snapshot
+** KEYWORDS: {snapshot}
+** EXPERIMENTAL
+**
+** An instance of the snapshot object records the state of a [WAL mode]
+** database for some specific point in history.
+**
+** In [WAL mode], multiple [database connections] that are open on the
+** same database file can each be reading a different historical version
+** of the database file.  When a [database connection] begins a read
+** transaction, that connection sees an unchanging copy of the database
+** as it existed for the point in time when the transaction first started.
+** Subsequent changes to the database from other connections are not seen
+** by the reader until a new read transaction is started.
+**
+** The sqlite3_snapshot object records state information about an historical
+** version of the database file so that it is possible to later open a new read
+** transaction that sees that historical version of the database rather than
+** the most recent version.
+**
+** The constructor for this object is [sqlite3_snapshot_get()].  The
+** [sqlite3_snapshot_open()] method causes a fresh read transaction to refer
+** to an historical snapshot (if possible).  The destructor for 
+** sqlite3_snapshot objects is [sqlite3_snapshot_free()].
+*/
+typedef struct sqlite3_snapshot sqlite3_snapshot;
+
+/*
+** CAPI3REF: Record A Database Snapshot
+** EXPERIMENTAL
+**
+** ^The [sqlite3_snapshot_get(D,S,P)] interface attempts to make a
+** new [sqlite3_snapshot] object that records the current state of
+** schema S in database connection D.  ^On success, the
+** [sqlite3_snapshot_get(D,S,P)] interface writes a pointer to the newly
+** created [sqlite3_snapshot] object into *P and returns SQLITE_OK.
+** ^If schema S of [database connection] D is not a [WAL mode] database
+** that is in a read transaction, then [sqlite3_snapshot_get(D,S,P)]
+** leaves the *P value unchanged and returns an appropriate [error code].
+**
+** The [sqlite3_snapshot] object returned from a successful call to
+** [sqlite3_snapshot_get()] must be freed using [sqlite3_snapshot_free()]
+** to avoid a memory leak.
+**
+** The [sqlite3_snapshot_get()] interface is only available when the
+** SQLITE_ENABLE_SNAPSHOT compile-time option is used.
+*/
+SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_snapshot_get(
+  sqlite3 *db,
+  const char *zSchema,
+  sqlite3_snapshot **ppSnapshot
+);
+
+/*
+** CAPI3REF: Start a read transaction on an historical snapshot
+** EXPERIMENTAL
+**
+** ^The [sqlite3_snapshot_open(D,S,P)] interface starts a
+** read transaction for schema S of
+** [database connection] D such that the read transaction
+** refers to historical [snapshot] P, rather than the most
+** recent change to the database.
+** ^The [sqlite3_snapshot_open()] interface returns SQLITE_OK on success
+** or an appropriate [error code] if it fails.
+**
+** ^In order to succeed, a call to [sqlite3_snapshot_open(D,S,P)] must be
+** the first operation following the [BEGIN] that takes the schema S
+** out of [autocommit mode].
+** ^In other words, schema S must not currently be in
+** a transaction for [sqlite3_snapshot_open(D,S,P)] to work, but the
+** database connection D must be out of [autocommit mode].
+** ^A [snapshot] will fail to open if it has been overwritten by a
+** [checkpoint].
+** ^(A call to [sqlite3_snapshot_open(D,S,P)] will fail if the
+** database connection D does not know that the database file for
+** schema S is in [WAL mode].  A database connection might not know
+** that the database file is in [WAL mode] if there has been no prior
+** I/O on that database connection, or if the database entered [WAL mode] 
+** after the most recent I/O on the database connection.)^
+** (Hint: Run "[PRAGMA application_id]" against a newly opened
+** database connection in order to make it ready to use snapshots.)
+**
+** The [sqlite3_snapshot_open()] interface is only available when the
+** SQLITE_ENABLE_SNAPSHOT compile-time option is used.
+*/
+SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_snapshot_open(
+  sqlite3 *db,
+  const char *zSchema,
+  sqlite3_snapshot *pSnapshot
+);
+
+/*
+** CAPI3REF: Destroy a snapshot
+** EXPERIMENTAL
+**
+** ^The [sqlite3_snapshot_free(P)] interface destroys [sqlite3_snapshot] P.
+** The application must eventually free every [sqlite3_snapshot] object
+** using this routine to avoid a memory leak.
+**
+** The [sqlite3_snapshot_free()] interface is only available when the
+** SQLITE_ENABLE_SNAPSHOT compile-time option is used.
+*/
+SQLITE_API SQLITE_EXPERIMENTAL void sqlite3_snapshot_free(sqlite3_snapshot*);
+
+/*
+** CAPI3REF: Compare the ages of two snapshot handles.
+** EXPERIMENTAL
+**
+** The sqlite3_snapshot_cmp(P1, P2) interface is used to compare the ages
+** of two valid snapshot handles. 
+**
+** If the two snapshot handles are not associated with the same database 
+** file, the result of the comparison is undefined. 
+**
+** Additionally, the result of the comparison is only valid if both of the
+** snapshot handles were obtained by calling sqlite3_snapshot_get() since the
+** last time the wal file was deleted. The wal file is deleted when the
+** database is changed back to rollback mode or when the number of database
+** clients drops to zero. If either snapshot handle was obtained before the 
+** wal file was last deleted, the value returned by this function 
+** is undefined.
+**
+** Otherwise, this API returns a negative value if P1 refers to an older
+** snapshot than P2, zero if the two handles refer to the same database
+** snapshot, and a positive value if P1 is a newer snapshot than P2.
+*/
+SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_snapshot_cmp(
+  sqlite3_snapshot *p1,
+  sqlite3_snapshot *p2
+);
+
+/*
+** Undo the hack that converts floating point types to integer for
+** builds on processors without floating point support.
+*/
+#ifdef SQLITE_OMIT_FLOATING_POINT
+# undef double
+#endif
+
+#ifdef __cplusplus
+}  /* End of the 'extern "C"' block */
+#endif
+#endif /* SQLITE3_H */
+
+/******** Begin file sqlite3rtree.h *********/
+/*
+** 2010 August 30
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+*/
+
+#ifndef _SQLITE3RTREE_H_
+#define _SQLITE3RTREE_H_
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct sqlite3_rtree_geometry sqlite3_rtree_geometry;
+typedef struct sqlite3_rtree_query_info sqlite3_rtree_query_info;
+
+/* The double-precision datatype used by RTree depends on the
+** SQLITE_RTREE_INT_ONLY compile-time option.
+*/
+#ifdef SQLITE_RTREE_INT_ONLY
+  typedef sqlite3_int64 sqlite3_rtree_dbl;
+#else
+  typedef double sqlite3_rtree_dbl;
+#endif
+
+/*
+** Register a geometry callback named zGeom that can be used as part of an
+** R-Tree geometry query as follows:
+**
+**   SELECT ... FROM <rtree> WHERE <rtree col> MATCH $zGeom(... params ...)
+*/
+SQLITE_API int sqlite3_rtree_geometry_callback(
+  sqlite3 *db,
+  const char *zGeom,
+  int (*xGeom)(sqlite3_rtree_geometry*, int, sqlite3_rtree_dbl*,int*),
+  void *pContext
+);
+
+
+/*
+** A pointer to a structure of the following type is passed as the first
+** argument to callbacks registered using rtree_geometry_callback().
+*/
+struct sqlite3_rtree_geometry {
+  void *pContext;                 /* Copy of pContext passed to s_r_g_c() */
+  int nParam;                     /* Size of array aParam[] */
+  sqlite3_rtree_dbl *aParam;      /* Parameters passed to SQL geom function */
+  void *pUser;                    /* Callback implementation user data */
+  void (*xDelUser)(void *);       /* Called by SQLite to clean up pUser */
+};
+
+/*
+** Register a 2nd-generation geometry callback named zScore that can be 
+** used as part of an R-Tree geometry query as follows:
+**
+**   SELECT ... FROM <rtree> WHERE <rtree col> MATCH $zQueryFunc(... params ...)
+*/
+SQLITE_API int sqlite3_rtree_query_callback(
+  sqlite3 *db,
+  const char *zQueryFunc,
+  int (*xQueryFunc)(sqlite3_rtree_query_info*),
+  void *pContext,
+  void (*xDestructor)(void*)
+);
+
+
+/*
+** A pointer to a structure of the following type is passed as the 
+** argument to scored geometry callback registered using
+** sqlite3_rtree_query_callback().
+**
+** Note that the first 5 fields of this structure are identical to
+** sqlite3_rtree_geometry.  This structure is a subclass of
+** sqlite3_rtree_geometry.
+*/
+struct sqlite3_rtree_query_info {
+  void *pContext;                   /* pContext from when function registered */
+  int nParam;                       /* Number of function parameters */
+  sqlite3_rtree_dbl *aParam;        /* value of function parameters */
+  void *pUser;                      /* callback can use this, if desired */
+  void (*xDelUser)(void*);          /* function to free pUser */
+  sqlite3_rtree_dbl *aCoord;        /* Coordinates of node or entry to check */
+  unsigned int *anQueue;            /* Number of pending entries in the queue */
+  int nCoord;                       /* Number of coordinates */
+  int iLevel;                       /* Level of current node or entry */
+  int mxLevel;                      /* The largest iLevel value in the tree */
+  sqlite3_int64 iRowid;             /* Rowid for current entry */
+  sqlite3_rtree_dbl rParentScore;   /* Score of parent node */
+  int eParentWithin;                /* Visibility of parent node */
+  int eWithin;                      /* OUT: Visiblity */
+  sqlite3_rtree_dbl rScore;         /* OUT: Write the score here */
+  /* The following fields are only available in 3.8.11 and later */
+  sqlite3_value **apSqlParam;       /* Original SQL values of parameters */
+};
+
+/*
+** Allowed values for sqlite3_rtree_query.eWithin and .eParentWithin.
+*/
+#define NOT_WITHIN       0   /* Object completely outside of query region */
+#define PARTLY_WITHIN    1   /* Object partially overlaps query region */
+#define FULLY_WITHIN     2   /* Object fully contained within query region */
+
+
+#ifdef __cplusplus
+}  /* end of the 'extern "C"' block */
+#endif
+
+#endif  /* ifndef _SQLITE3RTREE_H_ */
+
+/******** End of sqlite3rtree.h *********/
+/******** Begin file sqlite3session.h *********/
+
+#if !defined(__SQLITESESSION_H_) && defined(SQLITE_ENABLE_SESSION)
+#define __SQLITESESSION_H_ 1
+
+/*
+** Make sure we can call this stuff from C++.
+*/
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/*
+** CAPI3REF: Session Object Handle
+*/
+typedef struct sqlite3_session sqlite3_session;
+
+/*
+** CAPI3REF: Changeset Iterator Handle
+*/
+typedef struct sqlite3_changeset_iter sqlite3_changeset_iter;
+
+/*
+** CAPI3REF: Create A New Session Object
+**
+** Create a new session object attached to database handle db. If successful,
+** a pointer to the new object is written to *ppSession and SQLITE_OK is
+** returned. If an error occurs, *ppSession is set to NULL and an SQLite
+** error code (e.g. SQLITE_NOMEM) is returned.
+**
+** It is possible to create multiple session objects attached to a single
+** database handle.
+**
+** Session objects created using this function should be deleted using the
+** [sqlite3session_delete()] function before the database handle that they
+** are attached to is itself closed. If the database handle is closed before
+** the session object is deleted, then the results of calling any session
+** module function, including [sqlite3session_delete()] on the session object
+** are undefined.
+**
+** Because the session module uses the [sqlite3_preupdate_hook()] API, it
+** is not possible for an application to register a pre-update hook on a
+** database handle that has one or more session objects attached. Nor is
+** it possible to create a session object attached to a database handle for
+** which a pre-update hook is already defined. The results of attempting 
+** either of these things are undefined.
+**
+** The session object will be used to create changesets for tables in
+** database zDb, where zDb is either "main", or "temp", or the name of an
+** attached database. It is not an error if database zDb is not attached
+** to the database when the session object is created.
+*/
+int sqlite3session_create(
+  sqlite3 *db,                    /* Database handle */
+  const char *zDb,                /* Name of db (e.g. "main") */
+  sqlite3_session **ppSession     /* OUT: New session object */
+);
+
+/*
+** CAPI3REF: Delete A Session Object
+**
+** Delete a session object previously allocated using 
+** [sqlite3session_create()]. Once a session object has been deleted, the
+** results of attempting to use pSession with any other session module
+** function are undefined.
+**
+** Session objects must be deleted before the database handle to which they
+** are attached is closed. Refer to the documentation for 
+** [sqlite3session_create()] for details.
+*/
+void sqlite3session_delete(sqlite3_session *pSession);
+
+
+/*
+** CAPI3REF: Enable Or Disable A Session Object
+**
+** Enable or disable the recording of changes by a session object. When
+** enabled, a session object records changes made to the database. When
+** disabled - it does not. A newly created session object is enabled.
+** Refer to the documentation for [sqlite3session_changeset()] for further
+** details regarding how enabling and disabling a session object affects
+** the eventual changesets.
+**
+** Passing zero to this function disables the session. Passing a value
+** greater than zero enables it. Passing a value less than zero is a 
+** no-op, and may be used to query the current state of the session.
+**
+** The return value indicates the final state of the session object: 0 if 
+** the session is disabled, or 1 if it is enabled.
+*/
+int sqlite3session_enable(sqlite3_session *pSession, int bEnable);
+
+/*
+** CAPI3REF: Set Or Clear the Indirect Change Flag
+**
+** Each change recorded by a session object is marked as either direct or
+** indirect. A change is marked as indirect if either:
+**
+** <ul>
+**   <li> The session object "indirect" flag is set when the change is
+**        made, or
+**   <li> The change is made by an SQL trigger or foreign key action 
+**        instead of directly as a result of a users SQL statement.
+** </ul>
+**
+** If a single row is affected by more than one operation within a session,
+** then the change is considered indirect if all operations meet the criteria
+** for an indirect change above, or direct otherwise.
+**
+** This function is used to set, clear or query the session object indirect
+** flag.  If the second argument passed to this function is zero, then the
+** indirect flag is cleared. If it is greater than zero, the indirect flag
+** is set. Passing a value less than zero does not modify the current value
+** of the indirect flag, and may be used to query the current state of the 
+** indirect flag for the specified session object.
+**
+** The return value indicates the final state of the indirect flag: 0 if 
+** it is clear, or 1 if it is set.
+*/
+int sqlite3session_indirect(sqlite3_session *pSession, int bIndirect);
+
+/*
+** CAPI3REF: Attach A Table To A Session Object
+**
+** If argument zTab is not NULL, then it is the name of a table to attach
+** to the session object passed as the first argument. All subsequent changes 
+** made to the table while the session object is enabled will be recorded. See 
+** documentation for [sqlite3session_changeset()] for further details.
+**
+** Or, if argument zTab is NULL, then changes are recorded for all tables
+** in the database. If additional tables are added to the database (by 
+** executing "CREATE TABLE" statements) after this call is made, changes for 
+** the new tables are also recorded.
+**
+** Changes can only be recorded for tables that have a PRIMARY KEY explicitly
+** defined as part of their CREATE TABLE statement. It does not matter if the 
+** PRIMARY KEY is an "INTEGER PRIMARY KEY" (rowid alias) or not. The PRIMARY
+** KEY may consist of a single column, or may be a composite key.
+** 
+** It is not an error if the named table does not exist in the database. Nor
+** is it an error if the named table does not have a PRIMARY KEY. However,
+** no changes will be recorded in either of these scenarios.
+**
+** Changes are not recorded for individual rows that have NULL values stored
+** in one or more of their PRIMARY KEY columns.
+**
+** SQLITE_OK is returned if the call completes without error. Or, if an error 
+** occurs, an SQLite error code (e.g. SQLITE_NOMEM) is returned.
+*/
+int sqlite3session_attach(
+  sqlite3_session *pSession,      /* Session object */
+  const char *zTab                /* Table name */
+);
+
+/*
+** CAPI3REF: Set a table filter on a Session Object.
+**
+** The second argument (xFilter) is the "filter callback". For changes to rows 
+** in tables that are not attached to the Session object, the filter is called
+** to determine whether changes to the table's rows should be tracked or not. 
+** If xFilter returns 0, changes is not tracked. Note that once a table is 
+** attached, xFilter will not be called again.
+*/
+void sqlite3session_table_filter(
+  sqlite3_session *pSession,      /* Session object */
+  int(*xFilter)(
+    void *pCtx,                   /* Copy of third arg to _filter_table() */
+    const char *zTab              /* Table name */
+  ),
+  void *pCtx                      /* First argument passed to xFilter */
+);
+
+/*
+** CAPI3REF: Generate A Changeset From A Session Object
+**
+** Obtain a changeset containing changes to the tables attached to the 
+** session object passed as the first argument. If successful, 
+** set *ppChangeset to point to a buffer containing the changeset 
+** and *pnChangeset to the size of the changeset in bytes before returning
+** SQLITE_OK. If an error occurs, set both *ppChangeset and *pnChangeset to
+** zero and return an SQLite error code.
+**
+** A changeset consists of zero or more INSERT, UPDATE and/or DELETE changes,
+** each representing a change to a single row of an attached table. An INSERT
+** change contains the values of each field of a new database row. A DELETE
+** contains the original values of each field of a deleted database row. An
+** UPDATE change contains the original values of each field of an updated
+** database row along with the updated values for each updated non-primary-key
+** column. It is not possible for an UPDATE change to represent a change that
+** modifies the values of primary key columns. If such a change is made, it
+** is represented in a changeset as a DELETE followed by an INSERT.
+**
+** Changes are not recorded for rows that have NULL values stored in one or 
+** more of their PRIMARY KEY columns. If such a row is inserted or deleted,
+** no corresponding change is present in the changesets returned by this
+** function. If an existing row with one or more NULL values stored in
+** PRIMARY KEY columns is updated so that all PRIMARY KEY columns are non-NULL,
+** only an INSERT is appears in the changeset. Similarly, if an existing row
+** with non-NULL PRIMARY KEY values is updated so that one or more of its
+** PRIMARY KEY columns are set to NULL, the resulting changeset contains a
+** DELETE change only.
+**
+** The contents of a changeset may be traversed using an iterator created
+** using the [sqlite3changeset_start()] API. A changeset may be applied to
+** a database with a compatible schema using the [sqlite3changeset_apply()]
+** API.
+**
+** Within a changeset generated by this function, all changes related to a
+** single table are grouped together. In other words, when iterating through
+** a changeset or when applying a changeset to a database, all changes related
+** to a single table are processed before moving on to the next table. Tables
+** are sorted in the same order in which they were attached (or auto-attached)
+** to the sqlite3_session object. The order in which the changes related to
+** a single table are stored is undefined.
+**
+** Following a successful call to this function, it is the responsibility of
+** the caller to eventually free the buffer that *ppChangeset points to using
+** [sqlite3_free()].
+**
+** <h3>Changeset Generation</h3>
+**
+** Once a table has been attached to a session object, the session object
+** records the primary key values of all new rows inserted into the table.
+** It also records the original primary key and other column values of any
+** deleted or updated rows. For each unique primary key value, data is only
+** recorded once - the first time a row with said primary key is inserted,
+** updated or deleted in the lifetime of the session.
+**
+** There is one exception to the previous paragraph: when a row is inserted,
+** updated or deleted, if one or more of its primary key columns contain a
+** NULL value, no record of the change is made.
+**
+** The session object therefore accumulates two types of records - those
+** that consist of primary key values only (created when the user inserts
+** a new record) and those that consist of the primary key values and the
+** original values of other table columns (created when the users deletes
+** or updates a record).
+**
+** When this function is called, the requested changeset is created using
+** both the accumulated records and the current contents of the database
+** file. Specifically:
+**
+** <ul>
+**   <li> For each record generated by an insert, the database is queried
+**        for a row with a matching primary key. If one is found, an INSERT
+**        change is added to the changeset. If no such row is found, no change 
+**        is added to the changeset.
+**
+**   <li> For each record generated by an update or delete, the database is 
+**        queried for a row with a matching primary key. If such a row is
+**        found and one or more of the non-primary key fields have been
+**        modified from their original values, an UPDATE change is added to 
+**        the changeset. Or, if no such row is found in the table, a DELETE 
+**        change is added to the changeset. If there is a row with a matching
+**        primary key in the database, but all fields contain their original
+**        values, no change is added to the changeset.
+** </ul>
+**
+** This means, amongst other things, that if a row is inserted and then later
+** deleted while a session object is active, neither the insert nor the delete
+** will be present in the changeset. Or if a row is deleted and then later a 
+** row with the same primary key values inserted while a session object is
+** active, the resulting changeset will contain an UPDATE change instead of
+** a DELETE and an INSERT.
+**
+** When a session object is disabled (see the [sqlite3session_enable()] API),
+** it does not accumulate records when rows are inserted, updated or deleted.
+** This may appear to have some counter-intuitive effects if a single row
+** is written to more than once during a session. For example, if a row
+** is inserted while a session object is enabled, then later deleted while 
+** the same session object is disabled, no INSERT record will appear in the
+** changeset, even though the delete took place while the session was disabled.
+** Or, if one field of a row is updated while a session is disabled, and 
+** another field of the same row is updated while the session is enabled, the
+** resulting changeset will contain an UPDATE change that updates both fields.
+*/
+int sqlite3session_changeset(
+  sqlite3_session *pSession,      /* Session object */
+  int *pnChangeset,               /* OUT: Size of buffer at *ppChangeset */
+  void **ppChangeset              /* OUT: Buffer containing changeset */
+);
+
+/*
+** CAPI3REF: Load The Difference Between Tables Into A Session 
+**
+** If it is not already attached to the session object passed as the first
+** argument, this function attaches table zTbl in the same manner as the
+** [sqlite3session_attach()] function. If zTbl does not exist, or if it
+** does not have a primary key, this function is a no-op (but does not return
+** an error).
+**
+** Argument zFromDb must be the name of a database ("main", "temp" etc.)
+** attached to the same database handle as the session object that contains 
+** a table compatible with the table attached to the session by this function.
+** A table is considered compatible if it:
+**
+** <ul>
+**   <li> Has the same name,
+**   <li> Has the same set of columns declared in the same order, and
+**   <li> Has the same PRIMARY KEY definition.
+** </ul>
+**
+** If the tables are not compatible, SQLITE_SCHEMA is returned. If the tables
+** are compatible but do not have any PRIMARY KEY columns, it is not an error
+** but no changes are added to the session object. As with other session
+** APIs, tables without PRIMARY KEYs are simply ignored.
+**
+** This function adds a set of changes to the session object that could be
+** used to update the table in database zFrom (call this the "from-table") 
+** so that its content is the same as the table attached to the session 
+** object (call this the "to-table"). Specifically:
+**
+** <ul>
+**   <li> For each row (primary key) that exists in the to-table but not in 
+**     the from-table, an INSERT record is added to the session object.
+**
+**   <li> For each row (primary key) that exists in the to-table but not in 
+**     the from-table, a DELETE record is added to the session object.
+**
+**   <li> For each row (primary key) that exists in both tables, but features 
+**     different in each, an UPDATE record is added to the session.
+** </ul>
+**
+** To clarify, if this function is called and then a changeset constructed
+** using [sqlite3session_changeset()], then after applying that changeset to 
+** database zFrom the contents of the two compatible tables would be 
+** identical.
+**
+** It an error if database zFrom does not exist or does not contain the
+** required compatible table.
+**
+** If the operation successful, SQLITE_OK is returned. Otherwise, an SQLite
+** error code. In this case, if argument pzErrMsg is not NULL, *pzErrMsg
+** may be set to point to a buffer containing an English language error 
+** message. It is the responsibility of the caller to free this buffer using
+** sqlite3_free().
+*/
+int sqlite3session_diff(
+  sqlite3_session *pSession,
+  const char *zFromDb,
+  const char *zTbl,
+  char **pzErrMsg
+);
+
+
+/*
+** CAPI3REF: Generate A Patchset From A Session Object
+**
+** The differences between a patchset and a changeset are that:
+**
+** <ul>
+**   <li> DELETE records consist of the primary key fields only. The 
+**        original values of other fields are omitted.
+**   <li> The original values of any modified fields are omitted from 
+**        UPDATE records.
+** </ul>
+**
+** A patchset blob may be used with up to date versions of all 
+** sqlite3changeset_xxx API functions except for sqlite3changeset_invert(), 
+** which returns SQLITE_CORRUPT if it is passed a patchset. Similarly,
+** attempting to use a patchset blob with old versions of the
+** sqlite3changeset_xxx APIs also provokes an SQLITE_CORRUPT error. 
+**
+** Because the non-primary key "old.*" fields are omitted, no 
+** SQLITE_CHANGESET_DATA conflicts can be detected or reported if a patchset
+** is passed to the sqlite3changeset_apply() API. Other conflict types work
+** in the same way as for changesets.
+**
+** Changes within a patchset are ordered in the same way as for changesets
+** generated by the sqlite3session_changeset() function (i.e. all changes for
+** a single table are grouped together, tables appear in the order in which
+** they were attached to the session object).
+*/
+int sqlite3session_patchset(
+  sqlite3_session *pSession,      /* Session object */
+  int *pnPatchset,                /* OUT: Size of buffer at *ppChangeset */
+  void **ppPatchset               /* OUT: Buffer containing changeset */
+);
+
+/*
+** CAPI3REF: Test if a changeset has recorded any changes.
+**
+** Return non-zero if no changes to attached tables have been recorded by 
+** the session object passed as the first argument. Otherwise, if one or 
+** more changes have been recorded, return zero.
+**
+** Even if this function returns zero, it is possible that calling
+** [sqlite3session_changeset()] on the session handle may still return a
+** changeset that contains no changes. This can happen when a row in 
+** an attached table is modified and then later on the original values 
+** are restored. However, if this function returns non-zero, then it is
+** guaranteed that a call to sqlite3session_changeset() will return a 
+** changeset containing zero changes.
+*/
+int sqlite3session_isempty(sqlite3_session *pSession);
+
+/*
+** CAPI3REF: Create An Iterator To Traverse A Changeset 
+**
+** Create an iterator used to iterate through the contents of a changeset.
+** If successful, *pp is set to point to the iterator handle and SQLITE_OK
+** is returned. Otherwise, if an error occurs, *pp is set to zero and an
+** SQLite error code is returned.
+**
+** The following functions can be used to advance and query a changeset 
+** iterator created by this function:
+**
+** <ul>
+**   <li> [sqlite3changeset_next()]
+**   <li> [sqlite3changeset_op()]
+**   <li> [sqlite3changeset_new()]
+**   <li> [sqlite3changeset_old()]
+** </ul>
+**
+** It is the responsibility of the caller to eventually destroy the iterator
+** by passing it to [sqlite3changeset_finalize()]. The buffer containing the
+** changeset (pChangeset) must remain valid until after the iterator is
+** destroyed.
+**
+** Assuming the changeset blob was created by one of the
+** [sqlite3session_changeset()], [sqlite3changeset_concat()] or
+** [sqlite3changeset_invert()] functions, all changes within the changeset 
+** that apply to a single table are grouped together. This means that when 
+** an application iterates through a changeset using an iterator created by 
+** this function, all changes that relate to a single table are visited 
+** consecutively. There is no chance that the iterator will visit a change 
+** the applies to table X, then one for table Y, and then later on visit 
+** another change for table X.
+*/
+int sqlite3changeset_start(
+  sqlite3_changeset_iter **pp,    /* OUT: New changeset iterator handle */
+  int nChangeset,                 /* Size of changeset blob in bytes */
+  void *pChangeset                /* Pointer to blob containing changeset */
+);
+
+
+/*
+** CAPI3REF: Advance A Changeset Iterator
+**
+** This function may only be used with iterators created by function
+** [sqlite3changeset_start()]. If it is called on an iterator passed to
+** a conflict-handler callback by [sqlite3changeset_apply()], SQLITE_MISUSE
+** is returned and the call has no effect.
+**
+** Immediately after an iterator is created by sqlite3changeset_start(), it
+** does not point to any change in the changeset. Assuming the changeset
+** is not empty, the first call to this function advances the iterator to
+** point to the first change in the changeset. Each subsequent call advances
+** the iterator to point to the next change in the changeset (if any). If
+** no error occurs and the iterator points to a valid change after a call
+** to sqlite3changeset_next() has advanced it, SQLITE_ROW is returned. 
+** Otherwise, if all changes in the changeset have already been visited,
+** SQLITE_DONE is returned.
+**
+** If an error occurs, an SQLite error code is returned. Possible error 
+** codes include SQLITE_CORRUPT (if the changeset buffer is corrupt) or 
+** SQLITE_NOMEM.
+*/
+int sqlite3changeset_next(sqlite3_changeset_iter *pIter);
+
+/*
+** CAPI3REF: Obtain The Current Operation From A Changeset Iterator
+**
+** The pIter argument passed to this function may either be an iterator
+** passed to a conflict-handler by [sqlite3changeset_apply()], or an iterator
+** created by [sqlite3changeset_start()]. In the latter case, the most recent
+** call to [sqlite3changeset_next()] must have returned [SQLITE_ROW]. If this
+** is not the case, this function returns [SQLITE_MISUSE].
+**
+** If argument pzTab is not NULL, then *pzTab is set to point to a
+** nul-terminated utf-8 encoded string containing the name of the table
+** affected by the current change. The buffer remains valid until either
+** sqlite3changeset_next() is called on the iterator or until the 
+** conflict-handler function returns. If pnCol is not NULL, then *pnCol is 
+** set to the number of columns in the table affected by the change. If
+** pbIncorrect is not NULL, then *pbIndirect is set to true (1) if the change
+** is an indirect change, or false (0) otherwise. See the documentation for
+** [sqlite3session_indirect()] for a description of direct and indirect
+** changes. Finally, if pOp is not NULL, then *pOp is set to one of 
+** [SQLITE_INSERT], [SQLITE_DELETE] or [SQLITE_UPDATE], depending on the 
+** type of change that the iterator currently points to.
+**
+** If no error occurs, SQLITE_OK is returned. If an error does occur, an
+** SQLite error code is returned. The values of the output variables may not
+** be trusted in this case.
+*/
+int sqlite3changeset_op(
+  sqlite3_changeset_iter *pIter,  /* Iterator object */
+  const char **pzTab,             /* OUT: Pointer to table name */
+  int *pnCol,                     /* OUT: Number of columns in table */
+  int *pOp,                       /* OUT: SQLITE_INSERT, DELETE or UPDATE */
+  int *pbIndirect                 /* OUT: True for an 'indirect' change */
+);
+
+/*
+** CAPI3REF: Obtain The Primary Key Definition Of A Table
+**
+** For each modified table, a changeset includes the following:
+**
+** <ul>
+**   <li> The number of columns in the table, and
+**   <li> Which of those columns make up the tables PRIMARY KEY.
+** </ul>
+**
+** This function is used to find which columns comprise the PRIMARY KEY of
+** the table modified by the change that iterator pIter currently points to.
+** If successful, *pabPK is set to point to an array of nCol entries, where
+** nCol is the number of columns in the table. Elements of *pabPK are set to
+** 0x01 if the corresponding column is part of the tables primary key, or
+** 0x00 if it is not.
+**
+** If argument pnCol is not NULL, then *pnCol is set to the number of columns
+** in the table.
+**
+** If this function is called when the iterator does not point to a valid
+** entry, SQLITE_MISUSE is returned and the output variables zeroed. Otherwise,
+** SQLITE_OK is returned and the output variables populated as described
+** above.
+*/
+int sqlite3changeset_pk(
+  sqlite3_changeset_iter *pIter,  /* Iterator object */
+  unsigned char **pabPK,          /* OUT: Array of boolean - true for PK cols */
+  int *pnCol                      /* OUT: Number of entries in output array */
+);
+
+/*
+** CAPI3REF: Obtain old.* Values From A Changeset Iterator
+**
+** The pIter argument passed to this function may either be an iterator
+** passed to a conflict-handler by [sqlite3changeset_apply()], or an iterator
+** created by [sqlite3changeset_start()]. In the latter case, the most recent
+** call to [sqlite3changeset_next()] must have returned SQLITE_ROW. 
+** Furthermore, it may only be called if the type of change that the iterator
+** currently points to is either [SQLITE_DELETE] or [SQLITE_UPDATE]. Otherwise,
+** this function returns [SQLITE_MISUSE] and sets *ppValue to NULL.
+**
+** Argument iVal must be greater than or equal to 0, and less than the number
+** of columns in the table affected by the current change. Otherwise,
+** [SQLITE_RANGE] is returned and *ppValue is set to NULL.
+**
+** If successful, this function sets *ppValue to point to a protected
+** sqlite3_value object containing the iVal'th value from the vector of 
+** original row values stored as part of the UPDATE or DELETE change and
+** returns SQLITE_OK. The name of the function comes from the fact that this 
+** is similar to the "old.*" columns available to update or delete triggers.
+**
+** If some other error occurs (e.g. an OOM condition), an SQLite error code
+** is returned and *ppValue is set to NULL.
+*/
+int sqlite3changeset_old(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int iVal,                       /* Column number */
+  sqlite3_value **ppValue         /* OUT: Old value (or NULL pointer) */
+);
+
+/*
+** CAPI3REF: Obtain new.* Values From A Changeset Iterator
+**
+** The pIter argument passed to this function may either be an iterator
+** passed to a conflict-handler by [sqlite3changeset_apply()], or an iterator
+** created by [sqlite3changeset_start()]. In the latter case, the most recent
+** call to [sqlite3changeset_next()] must have returned SQLITE_ROW. 
+** Furthermore, it may only be called if the type of change that the iterator
+** currently points to is either [SQLITE_UPDATE] or [SQLITE_INSERT]. Otherwise,
+** this function returns [SQLITE_MISUSE] and sets *ppValue to NULL.
+**
+** Argument iVal must be greater than or equal to 0, and less than the number
+** of columns in the table affected by the current change. Otherwise,
+** [SQLITE_RANGE] is returned and *ppValue is set to NULL.
+**
+** If successful, this function sets *ppValue to point to a protected
+** sqlite3_value object containing the iVal'th value from the vector of 
+** new row values stored as part of the UPDATE or INSERT change and
+** returns SQLITE_OK. If the change is an UPDATE and does not include
+** a new value for the requested column, *ppValue is set to NULL and 
+** SQLITE_OK returned. The name of the function comes from the fact that 
+** this is similar to the "new.*" columns available to update or delete 
+** triggers.
+**
+** If some other error occurs (e.g. an OOM condition), an SQLite error code
+** is returned and *ppValue is set to NULL.
+*/
+int sqlite3changeset_new(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int iVal,                       /* Column number */
+  sqlite3_value **ppValue         /* OUT: New value (or NULL pointer) */
+);
+
+/*
+** CAPI3REF: Obtain Conflicting Row Values From A Changeset Iterator
+**
+** This function should only be used with iterator objects passed to a
+** conflict-handler callback by [sqlite3changeset_apply()] with either
+** [SQLITE_CHANGESET_DATA] or [SQLITE_CHANGESET_CONFLICT]. If this function
+** is called on any other iterator, [SQLITE_MISUSE] is returned and *ppValue
+** is set to NULL.
+**
+** Argument iVal must be greater than or equal to 0, and less than the number
+** of columns in the table affected by the current change. Otherwise,
+** [SQLITE_RANGE] is returned and *ppValue is set to NULL.
+**
+** If successful, this function sets *ppValue to point to a protected
+** sqlite3_value object containing the iVal'th value from the 
+** "conflicting row" associated with the current conflict-handler callback
+** and returns SQLITE_OK.
+**
+** If some other error occurs (e.g. an OOM condition), an SQLite error code
+** is returned and *ppValue is set to NULL.
+*/
+int sqlite3changeset_conflict(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int iVal,                       /* Column number */
+  sqlite3_value **ppValue         /* OUT: Value from conflicting row */
+);
+
+/*
+** CAPI3REF: Determine The Number Of Foreign Key Constraint Violations
+**
+** This function may only be called with an iterator passed to an
+** SQLITE_CHANGESET_FOREIGN_KEY conflict handler callback. In this case
+** it sets the output variable to the total number of known foreign key
+** violations in the destination database and returns SQLITE_OK.
+**
+** In all other cases this function returns SQLITE_MISUSE.
+*/
+int sqlite3changeset_fk_conflicts(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int *pnOut                      /* OUT: Number of FK violations */
+);
+
+
+/*
+** CAPI3REF: Finalize A Changeset Iterator
+**
+** This function is used to finalize an iterator allocated with
+** [sqlite3changeset_start()].
+**
+** This function should only be called on iterators created using the
+** [sqlite3changeset_start()] function. If an application calls this
+** function with an iterator passed to a conflict-handler by
+** [sqlite3changeset_apply()], [SQLITE_MISUSE] is immediately returned and the
+** call has no effect.
+**
+** If an error was encountered within a call to an sqlite3changeset_xxx()
+** function (for example an [SQLITE_CORRUPT] in [sqlite3changeset_next()] or an 
+** [SQLITE_NOMEM] in [sqlite3changeset_new()]) then an error code corresponding
+** to that error is returned by this function. Otherwise, SQLITE_OK is
+** returned. This is to allow the following pattern (pseudo-code):
+**
+**   sqlite3changeset_start();
+**   while( SQLITE_ROW==sqlite3changeset_next() ){
+**     // Do something with change.
+**   }
+**   rc = sqlite3changeset_finalize();
+**   if( rc!=SQLITE_OK ){
+**     // An error has occurred 
+**   }
+*/
+int sqlite3changeset_finalize(sqlite3_changeset_iter *pIter);
+
+/*
+** CAPI3REF: Invert A Changeset
+**
+** This function is used to "invert" a changeset object. Applying an inverted
+** changeset to a database reverses the effects of applying the uninverted
+** changeset. Specifically:
+**
+** <ul>
+**   <li> Each DELETE change is changed to an INSERT, and
+**   <li> Each INSERT change is changed to a DELETE, and
+**   <li> For each UPDATE change, the old.* and new.* values are exchanged.
+** </ul>
+**
+** This function does not change the order in which changes appear within
+** the changeset. It merely reverses the sense of each individual change.
+**
+** If successful, a pointer to a buffer containing the inverted changeset
+** is stored in *ppOut, the size of the same buffer is stored in *pnOut, and
+** SQLITE_OK is returned. If an error occurs, both *pnOut and *ppOut are
+** zeroed and an SQLite error code returned.
+**
+** It is the responsibility of the caller to eventually call sqlite3_free()
+** on the *ppOut pointer to free the buffer allocation following a successful 
+** call to this function.
+**
+** WARNING/TODO: This function currently assumes that the input is a valid
+** changeset. If it is not, the results are undefined.
+*/
+int sqlite3changeset_invert(
+  int nIn, const void *pIn,       /* Input changeset */
+  int *pnOut, void **ppOut        /* OUT: Inverse of input */
+);
+
+/*
+** CAPI3REF: Concatenate Two Changeset Objects
+**
+** This function is used to concatenate two changesets, A and B, into a 
+** single changeset. The result is a changeset equivalent to applying
+** changeset A followed by changeset B. 
+**
+** This function combines the two input changesets using an 
+** sqlite3_changegroup object. Calling it produces similar results as the
+** following code fragment:
+**
+**   sqlite3_changegroup *pGrp;
+**   rc = sqlite3_changegroup_new(&pGrp);
+**   if( rc==SQLITE_OK ) rc = sqlite3changegroup_add(pGrp, nA, pA);
+**   if( rc==SQLITE_OK ) rc = sqlite3changegroup_add(pGrp, nB, pB);
+**   if( rc==SQLITE_OK ){
+**     rc = sqlite3changegroup_output(pGrp, pnOut, ppOut);
+**   }else{
+**     *ppOut = 0;
+**     *pnOut = 0;
+**   }
+**
+** Refer to the sqlite3_changegroup documentation below for details.
+*/
+int sqlite3changeset_concat(
+  int nA,                         /* Number of bytes in buffer pA */
+  void *pA,                       /* Pointer to buffer containing changeset A */
+  int nB,                         /* Number of bytes in buffer pB */
+  void *pB,                       /* Pointer to buffer containing changeset B */
+  int *pnOut,                     /* OUT: Number of bytes in output changeset */
+  void **ppOut                    /* OUT: Buffer containing output changeset */
+);
+
+
+/*
+** CAPI3REF: Changegroup Handle
+*/
+typedef struct sqlite3_changegroup sqlite3_changegroup;
+
+/*
+** CAPI3REF: Create A New Changegroup Object
+**
+** An sqlite3_changegroup object is used to combine two or more changesets
+** (or patchsets) into a single changeset (or patchset). A single changegroup
+** object may combine changesets or patchsets, but not both. The output is
+** always in the same format as the input.
+**
+** If successful, this function returns SQLITE_OK and populates (*pp) with
+** a pointer to a new sqlite3_changegroup object before returning. The caller
+** should eventually free the returned object using a call to 
+** sqlite3changegroup_delete(). If an error occurs, an SQLite error code
+** (i.e. SQLITE_NOMEM) is returned and *pp is set to NULL.
+**
+** The usual usage pattern for an sqlite3_changegroup object is as follows:
+**
+** <ul>
+**   <li> It is created using a call to sqlite3changegroup_new().
+**
+**   <li> Zero or more changesets (or patchsets) are added to the object
+**        by calling sqlite3changegroup_add().
+**
+**   <li> The result of combining all input changesets together is obtained 
+**        by the application via a call to sqlite3changegroup_output().
+**
+**   <li> The object is deleted using a call to sqlite3changegroup_delete().
+** </ul>
+**
+** Any number of calls to add() and output() may be made between the calls to
+** new() and delete(), and in any order.
+**
+** As well as the regular sqlite3changegroup_add() and 
+** sqlite3changegroup_output() functions, also available are the streaming
+** versions sqlite3changegroup_add_strm() and sqlite3changegroup_output_strm().
+*/
+int sqlite3changegroup_new(sqlite3_changegroup **pp);
+
+/*
+** CAPI3REF: Add A Changeset To A Changegroup
+**
+** Add all changes within the changeset (or patchset) in buffer pData (size
+** nData bytes) to the changegroup. 
+**
+** If the buffer contains a patchset, then all prior calls to this function
+** on the same changegroup object must also have specified patchsets. Or, if
+** the buffer contains a changeset, so must have the earlier calls to this
+** function. Otherwise, SQLITE_ERROR is returned and no changes are added
+** to the changegroup.
+**
+** Rows within the changeset and changegroup are identified by the values in
+** their PRIMARY KEY columns. A change in the changeset is considered to
+** apply to the same row as a change already present in the changegroup if
+** the two rows have the same primary key.
+**
+** Changes to rows that do not already appear in the changegroup are
+** simply copied into it. Or, if both the new changeset and the changegroup
+** contain changes that apply to a single row, the final contents of the
+** changegroup depends on the type of each change, as follows:
+**
+** <table border=1 style="margin-left:8ex;margin-right:8ex">
+**   <tr><th style="white-space:pre">Existing Change  </th>
+**       <th style="white-space:pre">New Change       </th>
+**       <th>Output Change
+**   <tr><td>INSERT <td>INSERT <td>
+**       The new change is ignored. This case does not occur if the new
+**       changeset was recorded immediately after the changesets already
+**       added to the changegroup.
+**   <tr><td>INSERT <td>UPDATE <td>
+**       The INSERT change remains in the changegroup. The values in the 
+**       INSERT change are modified as if the row was inserted by the
+**       existing change and then updated according to the new change.
+**   <tr><td>INSERT <td>DELETE <td>
+**       The existing INSERT is removed from the changegroup. The DELETE is
+**       not added.
+**   <tr><td>UPDATE <td>INSERT <td>
+**       The new change is ignored. This case does not occur if the new
+**       changeset was recorded immediately after the changesets already
+**       added to the changegroup.
+**   <tr><td>UPDATE <td>UPDATE <td>
+**       The existing UPDATE remains within the changegroup. It is amended 
+**       so that the accompanying values are as if the row was updated once 
+**       by the existing change and then again by the new change.
+**   <tr><td>UPDATE <td>DELETE <td>
+**       The existing UPDATE is replaced by the new DELETE within the
+**       changegroup.
+**   <tr><td>DELETE <td>INSERT <td>
+**       If one or more of the column values in the row inserted by the
+**       new change differ from those in the row deleted by the existing 
+**       change, the existing DELETE is replaced by an UPDATE within the
+**       changegroup. Otherwise, if the inserted row is exactly the same 
+**       as the deleted row, the existing DELETE is simply discarded.
+**   <tr><td>DELETE <td>UPDATE <td>
+**       The new change is ignored. This case does not occur if the new
+**       changeset was recorded immediately after the changesets already
+**       added to the changegroup.
+**   <tr><td>DELETE <td>DELETE <td>
+**       The new change is ignored. This case does not occur if the new
+**       changeset was recorded immediately after the changesets already
+**       added to the changegroup.
+** </table>
+**
+** If the new changeset contains changes to a table that is already present
+** in the changegroup, then the number of columns and the position of the
+** primary key columns for the table must be consistent. If this is not the
+** case, this function fails with SQLITE_SCHEMA. If the input changeset
+** appears to be corrupt and the corruption is detected, SQLITE_CORRUPT is
+** returned. Or, if an out-of-memory condition occurs during processing, this
+** function returns SQLITE_NOMEM. In all cases, if an error occurs the
+** final contents of the changegroup is undefined.
+**
+** If no error occurs, SQLITE_OK is returned.
+*/
+int sqlite3changegroup_add(sqlite3_changegroup*, int nData, void *pData);
+
+/*
+** CAPI3REF: Obtain A Composite Changeset From A Changegroup
+**
+** Obtain a buffer containing a changeset (or patchset) representing the
+** current contents of the changegroup. If the inputs to the changegroup
+** were themselves changesets, the output is a changeset. Or, if the
+** inputs were patchsets, the output is also a patchset.
+**
+** As with the output of the sqlite3session_changeset() and
+** sqlite3session_patchset() functions, all changes related to a single
+** table are grouped together in the output of this function. Tables appear
+** in the same order as for the very first changeset added to the changegroup.
+** If the second or subsequent changesets added to the changegroup contain
+** changes for tables that do not appear in the first changeset, they are
+** appended onto the end of the output changeset, again in the order in
+** which they are first encountered.
+**
+** If an error occurs, an SQLite error code is returned and the output
+** variables (*pnData) and (*ppData) are set to 0. Otherwise, SQLITE_OK
+** is returned and the output variables are set to the size of and a 
+** pointer to the output buffer, respectively. In this case it is the
+** responsibility of the caller to eventually free the buffer using a
+** call to sqlite3_free().
+*/
+int sqlite3changegroup_output(
+  sqlite3_changegroup*,
+  int *pnData,                    /* OUT: Size of output buffer in bytes */
+  void **ppData                   /* OUT: Pointer to output buffer */
+);
+
+/*
+** CAPI3REF: Delete A Changegroup Object
+*/
+void sqlite3changegroup_delete(sqlite3_changegroup*);
+
+/*
+** CAPI3REF: Apply A Changeset To A Database
+**
+** Apply a changeset to a database. This function attempts to update the
+** "main" database attached to handle db with the changes found in the
+** changeset passed via the second and third arguments.
+**
+** The fourth argument (xFilter) passed to this function is the "filter
+** callback". If it is not NULL, then for each table affected by at least one
+** change in the changeset, the filter callback is invoked with
+** the table name as the second argument, and a copy of the context pointer
+** passed as the sixth argument to this function as the first. If the "filter
+** callback" returns zero, then no attempt is made to apply any changes to 
+** the table. Otherwise, if the return value is non-zero or the xFilter
+** argument to this function is NULL, all changes related to the table are
+** attempted.
+**
+** For each table that is not excluded by the filter callback, this function 
+** tests that the target database contains a compatible table. A table is 
+** considered compatible if all of the following are true:
+**
+** <ul>
+**   <li> The table has the same name as the name recorded in the 
+**        changeset, and
+**   <li> The table has the same number of columns as recorded in the 
+**        changeset, and
+**   <li> The table has primary key columns in the same position as 
+**        recorded in the changeset.
+** </ul>
+**
+** If there is no compatible table, it is not an error, but none of the
+** changes associated with the table are applied. A warning message is issued
+** via the sqlite3_log() mechanism with the error code SQLITE_SCHEMA. At most
+** one such warning is issued for each table in the changeset.
+**
+** For each change for which there is a compatible table, an attempt is made 
+** to modify the table contents according to the UPDATE, INSERT or DELETE 
+** change. If a change cannot be applied cleanly, the conflict handler 
+** function passed as the fifth argument to sqlite3changeset_apply() may be 
+** invoked. A description of exactly when the conflict handler is invoked for 
+** each type of change is below.
+**
+** Unlike the xFilter argument, xConflict may not be passed NULL. The results
+** of passing anything other than a valid function pointer as the xConflict
+** argument are undefined.
+**
+** Each time the conflict handler function is invoked, it must return one
+** of [SQLITE_CHANGESET_OMIT], [SQLITE_CHANGESET_ABORT] or 
+** [SQLITE_CHANGESET_REPLACE]. SQLITE_CHANGESET_REPLACE may only be returned
+** if the second argument passed to the conflict handler is either
+** SQLITE_CHANGESET_DATA or SQLITE_CHANGESET_CONFLICT. If the conflict-handler
+** returns an illegal value, any changes already made are rolled back and
+** the call to sqlite3changeset_apply() returns SQLITE_MISUSE. Different 
+** actions are taken by sqlite3changeset_apply() depending on the value
+** returned by each invocation of the conflict-handler function. Refer to
+** the documentation for the three 
+** [SQLITE_CHANGESET_OMIT|available return values] for details.
+**
+** <dl>
+** <dt>DELETE Changes<dd>
+**   For each DELETE change, this function checks if the target database 
+**   contains a row with the same primary key value (or values) as the 
+**   original row values stored in the changeset. If it does, and the values 
+**   stored in all non-primary key columns also match the values stored in 
+**   the changeset the row is deleted from the target database.
+**
+**   If a row with matching primary key values is found, but one or more of
+**   the non-primary key fields contains a value different from the original
+**   row value stored in the changeset, the conflict-handler function is
+**   invoked with [SQLITE_CHANGESET_DATA] as the second argument.
+**
+**   If no row with matching primary key values is found in the database,
+**   the conflict-handler function is invoked with [SQLITE_CHANGESET_NOTFOUND]
+**   passed as the second argument.
+**
+**   If the DELETE operation is attempted, but SQLite returns SQLITE_CONSTRAINT
+**   (which can only happen if a foreign key constraint is violated), the
+**   conflict-handler function is invoked with [SQLITE_CHANGESET_CONSTRAINT]
+**   passed as the second argument. This includes the case where the DELETE
+**   operation is attempted because an earlier call to the conflict handler
+**   function returned [SQLITE_CHANGESET_REPLACE].
+**
+** <dt>INSERT Changes<dd>
+**   For each INSERT change, an attempt is made to insert the new row into
+**   the database.
+**
+**   If the attempt to insert the row fails because the database already 
+**   contains a row with the same primary key values, the conflict handler
+**   function is invoked with the second argument set to 
+**   [SQLITE_CHANGESET_CONFLICT].
+**
+**   If the attempt to insert the row fails because of some other constraint
+**   violation (e.g. NOT NULL or UNIQUE), the conflict handler function is 
+**   invoked with the second argument set to [SQLITE_CHANGESET_CONSTRAINT].
+**   This includes the case where the INSERT operation is re-attempted because 
+**   an earlier call to the conflict handler function returned 
+**   [SQLITE_CHANGESET_REPLACE].
+**
+** <dt>UPDATE Changes<dd>
+**   For each UPDATE change, this function checks if the target database 
+**   contains a row with the same primary key value (or values) as the 
+**   original row values stored in the changeset. If it does, and the values 
+**   stored in all non-primary key columns also match the values stored in 
+**   the changeset the row is updated within the target database.
+**
+**   If a row with matching primary key values is found, but one or more of
+**   the non-primary key fields contains a value different from an original
+**   row value stored in the changeset, the conflict-handler function is
+**   invoked with [SQLITE_CHANGESET_DATA] as the second argument. Since
+**   UPDATE changes only contain values for non-primary key fields that are
+**   to be modified, only those fields need to match the original values to
+**   avoid the SQLITE_CHANGESET_DATA conflict-handler callback.
+**
+**   If no row with matching primary key values is found in the database,
+**   the conflict-handler function is invoked with [SQLITE_CHANGESET_NOTFOUND]
+**   passed as the second argument.
+**
+**   If the UPDATE operation is attempted, but SQLite returns 
+**   SQLITE_CONSTRAINT, the conflict-handler function is invoked with 
+**   [SQLITE_CHANGESET_CONSTRAINT] passed as the second argument.
+**   This includes the case where the UPDATE operation is attempted after 
+**   an earlier call to the conflict handler function returned
+**   [SQLITE_CHANGESET_REPLACE].  
+** </dl>
+**
+** It is safe to execute SQL statements, including those that write to the
+** table that the callback related to, from within the xConflict callback.
+** This can be used to further customize the applications conflict
+** resolution strategy.
+**
+** All changes made by this function are enclosed in a savepoint transaction.
+** If any other error (aside from a constraint failure when attempting to
+** write to the target database) occurs, then the savepoint transaction is
+** rolled back, restoring the target database to its original state, and an 
+** SQLite error code returned.
+*/
+int sqlite3changeset_apply(
+  sqlite3 *db,                    /* Apply change to "main" db of this handle */
+  int nChangeset,                 /* Size of changeset in bytes */
+  void *pChangeset,               /* Changeset blob */
+  int(*xFilter)(
+    void *pCtx,                   /* Copy of sixth arg to _apply() */
+    const char *zTab              /* Table name */
+  ),
+  int(*xConflict)(
+    void *pCtx,                   /* Copy of sixth arg to _apply() */
+    int eConflict,                /* DATA, MISSING, CONFLICT, CONSTRAINT */
+    sqlite3_changeset_iter *p     /* Handle describing change and conflict */
+  ),
+  void *pCtx                      /* First argument passed to xConflict */
+);
+
+/* 
+** CAPI3REF: Constants Passed To The Conflict Handler
+**
+** Values that may be passed as the second argument to a conflict-handler.
+**
+** <dl>
+** <dt>SQLITE_CHANGESET_DATA<dd>
+**   The conflict handler is invoked with CHANGESET_DATA as the second argument
+**   when processing a DELETE or UPDATE change if a row with the required
+**   PRIMARY KEY fields is present in the database, but one or more other 
+**   (non primary-key) fields modified by the update do not contain the 
+**   expected "before" values.
+** 
+**   The conflicting row, in this case, is the database row with the matching
+**   primary key.
+** 
+** <dt>SQLITE_CHANGESET_NOTFOUND<dd>
+**   The conflict handler is invoked with CHANGESET_NOTFOUND as the second
+**   argument when processing a DELETE or UPDATE change if a row with the
+**   required PRIMARY KEY fields is not present in the database.
+** 
+**   There is no conflicting row in this case. The results of invoking the
+**   sqlite3changeset_conflict() API are undefined.
+** 
+** <dt>SQLITE_CHANGESET_CONFLICT<dd>
+**   CHANGESET_CONFLICT is passed as the second argument to the conflict
+**   handler while processing an INSERT change if the operation would result 
+**   in duplicate primary key values.
+** 
+**   The conflicting row in this case is the database row with the matching
+**   primary key.
+**
+** <dt>SQLITE_CHANGESET_FOREIGN_KEY<dd>
+**   If foreign key handling is enabled, and applying a changeset leaves the
+**   database in a state containing foreign key violations, the conflict 
+**   handler is invoked with CHANGESET_FOREIGN_KEY as the second argument
+**   exactly once before the changeset is committed. If the conflict handler
+**   returns CHANGESET_OMIT, the changes, including those that caused the
+**   foreign key constraint violation, are committed. Or, if it returns
+**   CHANGESET_ABORT, the changeset is rolled back.
+**
+**   No current or conflicting row information is provided. The only function
+**   it is possible to call on the supplied sqlite3_changeset_iter handle
+**   is sqlite3changeset_fk_conflicts().
+** 
+** <dt>SQLITE_CHANGESET_CONSTRAINT<dd>
+**   If any other constraint violation occurs while applying a change (i.e. 
+**   a UNIQUE, CHECK or NOT NULL constraint), the conflict handler is 
+**   invoked with CHANGESET_CONSTRAINT as the second argument.
+** 
+**   There is no conflicting row in this case. The results of invoking the
+**   sqlite3changeset_conflict() API are undefined.
+**
+** </dl>
+*/
+#define SQLITE_CHANGESET_DATA        1
+#define SQLITE_CHANGESET_NOTFOUND    2
+#define SQLITE_CHANGESET_CONFLICT    3
+#define SQLITE_CHANGESET_CONSTRAINT  4
+#define SQLITE_CHANGESET_FOREIGN_KEY 5
+
+/* 
+** CAPI3REF: Constants Returned By The Conflict Handler
+**
+** A conflict handler callback must return one of the following three values.
+**
+** <dl>
+** <dt>SQLITE_CHANGESET_OMIT<dd>
+**   If a conflict handler returns this value no special action is taken. The
+**   change that caused the conflict is not applied. The session module 
+**   continues to the next change in the changeset.
+**
+** <dt>SQLITE_CHANGESET_REPLACE<dd>
+**   This value may only be returned if the second argument to the conflict
+**   handler was SQLITE_CHANGESET_DATA or SQLITE_CHANGESET_CONFLICT. If this
+**   is not the case, any changes applied so far are rolled back and the 
+**   call to sqlite3changeset_apply() returns SQLITE_MISUSE.
+**
+**   If CHANGESET_REPLACE is returned by an SQLITE_CHANGESET_DATA conflict
+**   handler, then the conflicting row is either updated or deleted, depending
+**   on the type of change.
+**
+**   If CHANGESET_REPLACE is returned by an SQLITE_CHANGESET_CONFLICT conflict
+**   handler, then the conflicting row is removed from the database and a
+**   second attempt to apply the change is made. If this second attempt fails,
+**   the original row is restored to the database before continuing.
+**
+** <dt>SQLITE_CHANGESET_ABORT<dd>
+**   If this value is returned, any changes applied so far are rolled back 
+**   and the call to sqlite3changeset_apply() returns SQLITE_ABORT.
+** </dl>
+*/
+#define SQLITE_CHANGESET_OMIT       0
+#define SQLITE_CHANGESET_REPLACE    1
+#define SQLITE_CHANGESET_ABORT      2
+
+/*
+** CAPI3REF: Streaming Versions of API functions.
+**
+** The six streaming API xxx_strm() functions serve similar purposes to the 
+** corresponding non-streaming API functions:
+**
+** <table border=1 style="margin-left:8ex;margin-right:8ex">
+**   <tr><th>Streaming function<th>Non-streaming equivalent</th>
+**   <tr><td>sqlite3changeset_apply_str<td>[sqlite3changeset_apply] 
+**   <tr><td>sqlite3changeset_concat_str<td>[sqlite3changeset_concat] 
+**   <tr><td>sqlite3changeset_invert_str<td>[sqlite3changeset_invert] 
+**   <tr><td>sqlite3changeset_start_str<td>[sqlite3changeset_start] 
+**   <tr><td>sqlite3session_changeset_str<td>[sqlite3session_changeset] 
+**   <tr><td>sqlite3session_patchset_str<td>[sqlite3session_patchset] 
+** </table>
+**
+** Non-streaming functions that accept changesets (or patchsets) as input
+** require that the entire changeset be stored in a single buffer in memory. 
+** Similarly, those that return a changeset or patchset do so by returning 
+** a pointer to a single large buffer allocated using sqlite3_malloc(). 
+** Normally this is convenient. However, if an application running in a 
+** low-memory environment is required to handle very large changesets, the
+** large contiguous memory allocations required can become onerous.
+**
+** In order to avoid this problem, instead of a single large buffer, input
+** is passed to a streaming API functions by way of a callback function that
+** the sessions module invokes to incrementally request input data as it is
+** required. In all cases, a pair of API function parameters such as
+**
+**  <pre>
+**  &nbsp;     int nChangeset,
+**  &nbsp;     void *pChangeset,
+**  </pre>
+**
+** Is replaced by:
+**
+**  <pre>
+**  &nbsp;     int (*xInput)(void *pIn, void *pData, int *pnData),
+**  &nbsp;     void *pIn,
+**  </pre>
+**
+** Each time the xInput callback is invoked by the sessions module, the first
+** argument passed is a copy of the supplied pIn context pointer. The second 
+** argument, pData, points to a buffer (*pnData) bytes in size. Assuming no 
+** error occurs the xInput method should copy up to (*pnData) bytes of data 
+** into the buffer and set (*pnData) to the actual number of bytes copied 
+** before returning SQLITE_OK. If the input is completely exhausted, (*pnData) 
+** should be set to zero to indicate this. Or, if an error occurs, an SQLite 
+** error code should be returned. In all cases, if an xInput callback returns
+** an error, all processing is abandoned and the streaming API function
+** returns a copy of the error code to the caller.
+**
+** In the case of sqlite3changeset_start_strm(), the xInput callback may be
+** invoked by the sessions module at any point during the lifetime of the
+** iterator. If such an xInput callback returns an error, the iterator enters
+** an error state, whereby all subsequent calls to iterator functions 
+** immediately fail with the same error code as returned by xInput.
+**
+** Similarly, streaming API functions that return changesets (or patchsets)
+** return them in chunks by way of a callback function instead of via a
+** pointer to a single large buffer. In this case, a pair of parameters such
+** as:
+**
+**  <pre>
+**  &nbsp;     int *pnChangeset,
+**  &nbsp;     void **ppChangeset,
+**  </pre>
+**
+** Is replaced by:
+**
+**  <pre>
+**  &nbsp;     int (*xOutput)(void *pOut, const void *pData, int nData),
+**  &nbsp;     void *pOut
+**  </pre>
+**
+** The xOutput callback is invoked zero or more times to return data to
+** the application. The first parameter passed to each call is a copy of the
+** pOut pointer supplied by the application. The second parameter, pData,
+** points to a buffer nData bytes in size containing the chunk of output
+** data being returned. If the xOutput callback successfully processes the
+** supplied data, it should return SQLITE_OK to indicate success. Otherwise,
+** it should return some other SQLite error code. In this case processing
+** is immediately abandoned and the streaming API function returns a copy
+** of the xOutput error code to the application.
+**
+** The sessions module never invokes an xOutput callback with the third 
+** parameter set to a value less than or equal to zero. Other than this,
+** no guarantees are made as to the size of the chunks of data returned.
+*/
+int sqlite3changeset_apply_strm(
+  sqlite3 *db,                    /* Apply change to "main" db of this handle */
+  int (*xInput)(void *pIn, void *pData, int *pnData), /* Input function */
+  void *pIn,                                          /* First arg for xInput */
+  int(*xFilter)(
+    void *pCtx,                   /* Copy of sixth arg to _apply() */
+    const char *zTab              /* Table name */
+  ),
+  int(*xConflict)(
+    void *pCtx,                   /* Copy of sixth arg to _apply() */
+    int eConflict,                /* DATA, MISSING, CONFLICT, CONSTRAINT */
+    sqlite3_changeset_iter *p     /* Handle describing change and conflict */
+  ),
+  void *pCtx                      /* First argument passed to xConflict */
+);
+int sqlite3changeset_concat_strm(
+  int (*xInputA)(void *pIn, void *pData, int *pnData),
+  void *pInA,
+  int (*xInputB)(void *pIn, void *pData, int *pnData),
+  void *pInB,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut
+);
+int sqlite3changeset_invert_strm(
+  int (*xInput)(void *pIn, void *pData, int *pnData),
+  void *pIn,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut
+);
+int sqlite3changeset_start_strm(
+  sqlite3_changeset_iter **pp,
+  int (*xInput)(void *pIn, void *pData, int *pnData),
+  void *pIn
+);
+int sqlite3session_changeset_strm(
+  sqlite3_session *pSession,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut
+);
+int sqlite3session_patchset_strm(
+  sqlite3_session *pSession,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut
+);
+int sqlite3changegroup_add_strm(sqlite3_changegroup*, 
+    int (*xInput)(void *pIn, void *pData, int *pnData),
+    void *pIn
+);
+int sqlite3changegroup_output_strm(sqlite3_changegroup*,
+    int (*xOutput)(void *pOut, const void *pData, int nData), 
+    void *pOut
+);
+
+
+/*
+** Make sure we can call this stuff from C++.
+*/
+#ifdef __cplusplus
+}
+#endif
+
+#endif  /* !defined(__SQLITESESSION_H_) && defined(SQLITE_ENABLE_SESSION) */
+
+/******** End of sqlite3session.h *********/
+/******** Begin file fts5.h *********/
+/*
+** 2014 May 31
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** Interfaces to extend FTS5. Using the interfaces defined in this file, 
+** FTS5 may be extended with:
+**
+**     * custom tokenizers, and
+**     * custom auxiliary functions.
+*/
+
+
+#ifndef _FTS5_H
+#define _FTS5_H
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*************************************************************************
+** CUSTOM AUXILIARY FUNCTIONS
+**
+** Virtual table implementations may overload SQL functions by implementing
+** the sqlite3_module.xFindFunction() method.
+*/
+
+typedef struct Fts5ExtensionApi Fts5ExtensionApi;
+typedef struct Fts5Context Fts5Context;
+typedef struct Fts5PhraseIter Fts5PhraseIter;
+
+typedef void (*fts5_extension_function)(
+  const Fts5ExtensionApi *pApi,   /* API offered by current FTS version */
+  Fts5Context *pFts,              /* First arg to pass to pApi functions */
+  sqlite3_context *pCtx,          /* Context for returning result/error */
+  int nVal,                       /* Number of values in apVal[] array */
+  sqlite3_value **apVal           /* Array of trailing arguments */
+);
+
+struct Fts5PhraseIter {
+  const unsigned char *a;
+  const unsigned char *b;
+};
+
+/*
+** EXTENSION API FUNCTIONS
+**
+** xUserData(pFts):
+**   Return a copy of the context pointer the extension function was 
+**   registered with.
+**
+** xColumnTotalSize(pFts, iCol, pnToken):
+**   If parameter iCol is less than zero, set output variable *pnToken
+**   to the total number of tokens in the FTS5 table. Or, if iCol is
+**   non-negative but less than the number of columns in the table, return
+**   the total number of tokens in column iCol, considering all rows in 
+**   the FTS5 table.
+**
+**   If parameter iCol is greater than or equal to the number of columns
+**   in the table, SQLITE_RANGE is returned. Or, if an error occurs (e.g.
+**   an OOM condition or IO error), an appropriate SQLite error code is 
+**   returned.
+**
+** xColumnCount(pFts):
+**   Return the number of columns in the table.
+**
+** xColumnSize(pFts, iCol, pnToken):
+**   If parameter iCol is less than zero, set output variable *pnToken
+**   to the total number of tokens in the current row. Or, if iCol is
+**   non-negative but less than the number of columns in the table, set
+**   *pnToken to the number of tokens in column iCol of the current row.
+**
+**   If parameter iCol is greater than or equal to the number of columns
+**   in the table, SQLITE_RANGE is returned. Or, if an error occurs (e.g.
+**   an OOM condition or IO error), an appropriate SQLite error code is 
+**   returned.
+**
+**   This function may be quite inefficient if used with an FTS5 table
+**   created with the "columnsize=0" option.
+**
+** xColumnText:
+**   This function attempts to retrieve the text of column iCol of the
+**   current document. If successful, (*pz) is set to point to a buffer
+**   containing the text in utf-8 encoding, (*pn) is set to the size in bytes
+**   (not characters) of the buffer and SQLITE_OK is returned. Otherwise,
+**   if an error occurs, an SQLite error code is returned and the final values
+**   of (*pz) and (*pn) are undefined.
+**
+** xPhraseCount:
+**   Returns the number of phrases in the current query expression.
+**
+** xPhraseSize:
+**   Returns the number of tokens in phrase iPhrase of the query. Phrases
+**   are numbered starting from zero.
+**
+** xInstCount:
+**   Set *pnInst to the total number of occurrences of all phrases within
+**   the query within the current row. Return SQLITE_OK if successful, or
+**   an error code (i.e. SQLITE_NOMEM) if an error occurs.
+**
+**   This API can be quite slow if used with an FTS5 table created with the
+**   "detail=none" or "detail=column" option. If the FTS5 table is created 
+**   with either "detail=none" or "detail=column" and "content=" option 
+**   (i.e. if it is a contentless table), then this API always returns 0.
+**
+** xInst:
+**   Query for the details of phrase match iIdx within the current row.
+**   Phrase matches are numbered starting from zero, so the iIdx argument
+**   should be greater than or equal to zero and smaller than the value
+**   output by xInstCount().
+**
+**   Usually, output parameter *piPhrase is set to the phrase number, *piCol
+**   to the column in which it occurs and *piOff the token offset of the
+**   first token of the phrase. The exception is if the table was created
+**   with the offsets=0 option specified. In this case *piOff is always
+**   set to -1.
+**
+**   Returns SQLITE_OK if successful, or an error code (i.e. SQLITE_NOMEM) 
+**   if an error occurs.
+**
+**   This API can be quite slow if used with an FTS5 table created with the
+**   "detail=none" or "detail=column" option. 
+**
+** xRowid:
+**   Returns the rowid of the current row.
+**
+** xTokenize:
+**   Tokenize text using the tokenizer belonging to the FTS5 table.
+**
+** xQueryPhrase(pFts5, iPhrase, pUserData, xCallback):
+**   This API function is used to query the FTS table for phrase iPhrase
+**   of the current query. Specifically, a query equivalent to:
+**
+**       ... FROM ftstable WHERE ftstable MATCH $p ORDER BY rowid
+**
+**   with $p set to a phrase equivalent to the phrase iPhrase of the
+**   current query is executed. Any column filter that applies to
+**   phrase iPhrase of the current query is included in $p. For each 
+**   row visited, the callback function passed as the fourth argument 
+**   is invoked. The context and API objects passed to the callback 
+**   function may be used to access the properties of each matched row.
+**   Invoking Api.xUserData() returns a copy of the pointer passed as 
+**   the third argument to pUserData.
+**
+**   If the callback function returns any value other than SQLITE_OK, the
+**   query is abandoned and the xQueryPhrase function returns immediately.
+**   If the returned value is SQLITE_DONE, xQueryPhrase returns SQLITE_OK.
+**   Otherwise, the error code is propagated upwards.
+**
+**   If the query runs to completion without incident, SQLITE_OK is returned.
+**   Or, if some error occurs before the query completes or is aborted by
+**   the callback, an SQLite error code is returned.
+**
+**
+** xSetAuxdata(pFts5, pAux, xDelete)
+**
+**   Save the pointer passed as the second argument as the extension functions 
+**   "auxiliary data". The pointer may then be retrieved by the current or any
+**   future invocation of the same fts5 extension function made as part of
+**   of the same MATCH query using the xGetAuxdata() API.
+**
+**   Each extension function is allocated a single auxiliary data slot for
+**   each FTS query (MATCH expression). If the extension function is invoked 
+**   more than once for a single FTS query, then all invocations share a 
+**   single auxiliary data context.
+**
+**   If there is already an auxiliary data pointer when this function is
+**   invoked, then it is replaced by the new pointer. If an xDelete callback
+**   was specified along with the original pointer, it is invoked at this
+**   point.
+**
+**   The xDelete callback, if one is specified, is also invoked on the
+**   auxiliary data pointer after the FTS5 query has finished.
+**
+**   If an error (e.g. an OOM condition) occurs within this function, an
+**   the auxiliary data is set to NULL and an error code returned. If the
+**   xDelete parameter was not NULL, it is invoked on the auxiliary data
+**   pointer before returning.
+**
+**
+** xGetAuxdata(pFts5, bClear)
+**
+**   Returns the current auxiliary data pointer for the fts5 extension 
+**   function. See the xSetAuxdata() method for details.
+**
+**   If the bClear argument is non-zero, then the auxiliary data is cleared
+**   (set to NULL) before this function returns. In this case the xDelete,
+**   if any, is not invoked.
+**
+**
+** xRowCount(pFts5, pnRow)
+**
+**   This function is used to retrieve the total number of rows in the table.
+**   In other words, the same value that would be returned by:
+**
+**        SELECT count(*) FROM ftstable;
+**
+** xPhraseFirst()
+**   This function is used, along with type Fts5PhraseIter and the xPhraseNext
+**   method, to iterate through all instances of a single query phrase within
+**   the current row. This is the same information as is accessible via the
+**   xInstCount/xInst APIs. While the xInstCount/xInst APIs are more convenient
+**   to use, this API may be faster under some circumstances. To iterate 
+**   through instances of phrase iPhrase, use the following code:
+**
+**       Fts5PhraseIter iter;
+**       int iCol, iOff;
+**       for(pApi->xPhraseFirst(pFts, iPhrase, &iter, &iCol, &iOff);
+**           iCol>=0;
+**           pApi->xPhraseNext(pFts, &iter, &iCol, &iOff)
+**       ){
+**         // An instance of phrase iPhrase at offset iOff of column iCol
+**       }
+**
+**   The Fts5PhraseIter structure is defined above. Applications should not
+**   modify this structure directly - it should only be used as shown above
+**   with the xPhraseFirst() and xPhraseNext() API methods (and by
+**   xPhraseFirstColumn() and xPhraseNextColumn() as illustrated below).
+**
+**   This API can be quite slow if used with an FTS5 table created with the
+**   "detail=none" or "detail=column" option. If the FTS5 table is created 
+**   with either "detail=none" or "detail=column" and "content=" option 
+**   (i.e. if it is a contentless table), then this API always iterates
+**   through an empty set (all calls to xPhraseFirst() set iCol to -1).
+**
+** xPhraseNext()
+**   See xPhraseFirst above.
+**
+** xPhraseFirstColumn()
+**   This function and xPhraseNextColumn() are similar to the xPhraseFirst()
+**   and xPhraseNext() APIs described above. The difference is that instead
+**   of iterating through all instances of a phrase in the current row, these
+**   APIs are used to iterate through the set of columns in the current row
+**   that contain one or more instances of a specified phrase. For example:
+**
+**       Fts5PhraseIter iter;
+**       int iCol;
+**       for(pApi->xPhraseFirstColumn(pFts, iPhrase, &iter, &iCol);
+**           iCol>=0;
+**           pApi->xPhraseNextColumn(pFts, &iter, &iCol)
+**       ){
+**         // Column iCol contains at least one instance of phrase iPhrase
+**       }
+**
+**   This API can be quite slow if used with an FTS5 table created with the
+**   "detail=none" option. If the FTS5 table is created with either 
+**   "detail=none" "content=" option (i.e. if it is a contentless table), 
+**   then this API always iterates through an empty set (all calls to 
+**   xPhraseFirstColumn() set iCol to -1).
+**
+**   The information accessed using this API and its companion
+**   xPhraseFirstColumn() may also be obtained using xPhraseFirst/xPhraseNext
+**   (or xInst/xInstCount). The chief advantage of this API is that it is
+**   significantly more efficient than those alternatives when used with
+**   "detail=column" tables.  
+**
+** xPhraseNextColumn()
+**   See xPhraseFirstColumn above.
+*/
+struct Fts5ExtensionApi {
+  int iVersion;                   /* Currently always set to 3 */
+
+  void *(*xUserData)(Fts5Context*);
+
+  int (*xColumnCount)(Fts5Context*);
+  int (*xRowCount)(Fts5Context*, sqlite3_int64 *pnRow);
+  int (*xColumnTotalSize)(Fts5Context*, int iCol, sqlite3_int64 *pnToken);
+
+  int (*xTokenize)(Fts5Context*, 
+    const char *pText, int nText, /* Text to tokenize */
+    void *pCtx,                   /* Context passed to xToken() */
+    int (*xToken)(void*, int, const char*, int, int, int)       /* Callback */
+  );
+
+  int (*xPhraseCount)(Fts5Context*);
+  int (*xPhraseSize)(Fts5Context*, int iPhrase);
+
+  int (*xInstCount)(Fts5Context*, int *pnInst);
+  int (*xInst)(Fts5Context*, int iIdx, int *piPhrase, int *piCol, int *piOff);
+
+  sqlite3_int64 (*xRowid)(Fts5Context*);
+  int (*xColumnText)(Fts5Context*, int iCol, const char **pz, int *pn);
+  int (*xColumnSize)(Fts5Context*, int iCol, int *pnToken);
+
+  int (*xQueryPhrase)(Fts5Context*, int iPhrase, void *pUserData,
+    int(*)(const Fts5ExtensionApi*,Fts5Context*,void*)
+  );
+  int (*xSetAuxdata)(Fts5Context*, void *pAux, void(*xDelete)(void*));
+  void *(*xGetAuxdata)(Fts5Context*, int bClear);
+
+  int (*xPhraseFirst)(Fts5Context*, int iPhrase, Fts5PhraseIter*, int*, int*);
+  void (*xPhraseNext)(Fts5Context*, Fts5PhraseIter*, int *piCol, int *piOff);
+
+  int (*xPhraseFirstColumn)(Fts5Context*, int iPhrase, Fts5PhraseIter*, int*);
+  void (*xPhraseNextColumn)(Fts5Context*, Fts5PhraseIter*, int *piCol);
+};
+
+/* 
+** CUSTOM AUXILIARY FUNCTIONS
+*************************************************************************/
+
+/*************************************************************************
+** CUSTOM TOKENIZERS
+**
+** Applications may also register custom tokenizer types. A tokenizer 
+** is registered by providing fts5 with a populated instance of the 
+** following structure. All structure methods must be defined, setting
+** any member of the fts5_tokenizer struct to NULL leads to undefined
+** behaviour. The structure methods are expected to function as follows:
+**
+** xCreate:
+**   This function is used to allocate and initialize a tokenizer instance.
+**   A tokenizer instance is required to actually tokenize text.
+**
+**   The first argument passed to this function is a copy of the (void*)
+**   pointer provided by the application when the fts5_tokenizer object
+**   was registered with FTS5 (the third argument to xCreateTokenizer()). 
+**   The second and third arguments are an array of nul-terminated strings
+**   containing the tokenizer arguments, if any, specified following the
+**   tokenizer name as part of the CREATE VIRTUAL TABLE statement used
+**   to create the FTS5 table.
+**
+**   The final argument is an output variable. If successful, (*ppOut) 
+**   should be set to point to the new tokenizer handle and SQLITE_OK
+**   returned. If an error occurs, some value other than SQLITE_OK should
+**   be returned. In this case, fts5 assumes that the final value of *ppOut 
+**   is undefined.
+**
+** xDelete:
+**   This function is invoked to delete a tokenizer handle previously
+**   allocated using xCreate(). Fts5 guarantees that this function will
+**   be invoked exactly once for each successful call to xCreate().
+**
+** xTokenize:
+**   This function is expected to tokenize the nText byte string indicated 
+**   by argument pText. pText may or may not be nul-terminated. The first
+**   argument passed to this function is a pointer to an Fts5Tokenizer object
+**   returned by an earlier call to xCreate().
+**
+**   The second argument indicates the reason that FTS5 is requesting
+**   tokenization of the supplied text. This is always one of the following
+**   four values:
+**
+**   <ul><li> <b>FTS5_TOKENIZE_DOCUMENT</b> - A document is being inserted into
+**            or removed from the FTS table. The tokenizer is being invoked to
+**            determine the set of tokens to add to (or delete from) the
+**            FTS index.
+**
+**       <li> <b>FTS5_TOKENIZE_QUERY</b> - A MATCH query is being executed 
+**            against the FTS index. The tokenizer is being called to tokenize 
+**            a bareword or quoted string specified as part of the query.
+**
+**       <li> <b>(FTS5_TOKENIZE_QUERY | FTS5_TOKENIZE_PREFIX)</b> - Same as
+**            FTS5_TOKENIZE_QUERY, except that the bareword or quoted string is
+**            followed by a "*" character, indicating that the last token
+**            returned by the tokenizer will be treated as a token prefix.
+**
+**       <li> <b>FTS5_TOKENIZE_AUX</b> - The tokenizer is being invoked to 
+**            satisfy an fts5_api.xTokenize() request made by an auxiliary
+**            function. Or an fts5_api.xColumnSize() request made by the same
+**            on a columnsize=0 database.  
+**   </ul>
+**
+**   For each token in the input string, the supplied callback xToken() must
+**   be invoked. The first argument to it should be a copy of the pointer
+**   passed as the second argument to xTokenize(). The third and fourth
+**   arguments are a pointer to a buffer containing the token text, and the
+**   size of the token in bytes. The 4th and 5th arguments are the byte offsets
+**   of the first byte of and first byte immediately following the text from
+**   which the token is derived within the input.
+**
+**   The second argument passed to the xToken() callback ("tflags") should
+**   normally be set to 0. The exception is if the tokenizer supports 
+**   synonyms. In this case see the discussion below for details.
+**
+**   FTS5 assumes the xToken() callback is invoked for each token in the 
+**   order that they occur within the input text.
+**
+**   If an xToken() callback returns any value other than SQLITE_OK, then
+**   the tokenization should be abandoned and the xTokenize() method should
+**   immediately return a copy of the xToken() return value. Or, if the
+**   input buffer is exhausted, xTokenize() should return SQLITE_OK. Finally,
+**   if an error occurs with the xTokenize() implementation itself, it
+**   may abandon the tokenization and return any error code other than
+**   SQLITE_OK or SQLITE_DONE.
+**
+** SYNONYM SUPPORT
+**
+**   Custom tokenizers may also support synonyms. Consider a case in which a
+**   user wishes to query for a phrase such as "first place". Using the 
+**   built-in tokenizers, the FTS5 query 'first + place' will match instances
+**   of "first place" within the document set, but not alternative forms
+**   such as "1st place". In some applications, it would be better to match
+**   all instances of "first place" or "1st place" regardless of which form
+**   the user specified in the MATCH query text.
+**
+**   There are several ways to approach this in FTS5:
+**
+**   <ol><li> By mapping all synonyms to a single token. In this case, the 
+**            In the above example, this means that the tokenizer returns the
+**            same token for inputs "first" and "1st". Say that token is in
+**            fact "first", so that when the user inserts the document "I won
+**            1st place" entries are added to the index for tokens "i", "won",
+**            "first" and "place". If the user then queries for '1st + place',
+**            the tokenizer substitutes "first" for "1st" and the query works
+**            as expected.
+**
+**       <li> By adding multiple synonyms for a single term to the FTS index.
+**            In this case, when tokenizing query text, the tokenizer may 
+**            provide multiple synonyms for a single term within the document.
+**            FTS5 then queries the index for each synonym individually. For
+**            example, faced with the query:
+**
+**   <codeblock>
+**     ... MATCH 'first place'</codeblock>
+**
+**            the tokenizer offers both "1st" and "first" as synonyms for the
+**            first token in the MATCH query and FTS5 effectively runs a query 
+**            similar to:
+**
+**   <codeblock>
+**     ... MATCH '(first OR 1st) place'</codeblock>
+**
+**            except that, for the purposes of auxiliary functions, the query
+**            still appears to contain just two phrases - "(first OR 1st)" 
+**            being treated as a single phrase.
+**
+**       <li> By adding multiple synonyms for a single term to the FTS index.
+**            Using this method, when tokenizing document text, the tokenizer
+**            provides multiple synonyms for each token. So that when a 
+**            document such as "I won first place" is tokenized, entries are
+**            added to the FTS index for "i", "won", "first", "1st" and
+**            "place".
+**
+**            This way, even if the tokenizer does not provide synonyms
+**            when tokenizing query text (it should not - to do would be
+**            inefficient), it doesn't matter if the user queries for 
+**            'first + place' or '1st + place', as there are entires in the
+**            FTS index corresponding to both forms of the first token.
+**   </ol>
+**
+**   Whether it is parsing document or query text, any call to xToken that
+**   specifies a <i>tflags</i> argument with the FTS5_TOKEN_COLOCATED bit
+**   is considered to supply a synonym for the previous token. For example,
+**   when parsing the document "I won first place", a tokenizer that supports
+**   synonyms would call xToken() 5 times, as follows:
+**
+**   <codeblock>
+**       xToken(pCtx, 0, "i",                      1,  0,  1);
+**       xToken(pCtx, 0, "won",                    3,  2,  5);
+**       xToken(pCtx, 0, "first",                  5,  6, 11);
+**       xToken(pCtx, FTS5_TOKEN_COLOCATED, "1st", 3,  6, 11);
+**       xToken(pCtx, 0, "place",                  5, 12, 17);
+**</codeblock>
+**
+**   It is an error to specify the FTS5_TOKEN_COLOCATED flag the first time
+**   xToken() is called. Multiple synonyms may be specified for a single token
+**   by making multiple calls to xToken(FTS5_TOKEN_COLOCATED) in sequence. 
+**   There is no limit to the number of synonyms that may be provided for a
+**   single token.
+**
+**   In many cases, method (1) above is the best approach. It does not add 
+**   extra data to the FTS index or require FTS5 to query for multiple terms,
+**   so it is efficient in terms of disk space and query speed. However, it
+**   does not support prefix queries very well. If, as suggested above, the
+**   token "first" is subsituted for "1st" by the tokenizer, then the query:
+**
+**   <codeblock>
+**     ... MATCH '1s*'</codeblock>
+**
+**   will not match documents that contain the token "1st" (as the tokenizer
+**   will probably not map "1s" to any prefix of "first").
+**
+**   For full prefix support, method (3) may be preferred. In this case, 
+**   because the index contains entries for both "first" and "1st", prefix
+**   queries such as 'fi*' or '1s*' will match correctly. However, because
+**   extra entries are added to the FTS index, this method uses more space
+**   within the database.
+**
+**   Method (2) offers a midpoint between (1) and (3). Using this method,
+**   a query such as '1s*' will match documents that contain the literal 
+**   token "1st", but not "first" (assuming the tokenizer is not able to
+**   provide synonyms for prefixes). However, a non-prefix query like '1st'
+**   will match against "1st" and "first". This method does not require
+**   extra disk space, as no extra entries are added to the FTS index. 
+**   On the other hand, it may require more CPU cycles to run MATCH queries,
+**   as separate queries of the FTS index are required for each synonym.
+**
+**   When using methods (2) or (3), it is important that the tokenizer only
+**   provide synonyms when tokenizing document text (method (2)) or query
+**   text (method (3)), not both. Doing so will not cause any errors, but is
+**   inefficient.
+*/
+typedef struct Fts5Tokenizer Fts5Tokenizer;
+typedef struct fts5_tokenizer fts5_tokenizer;
+struct fts5_tokenizer {
+  int (*xCreate)(void*, const char **azArg, int nArg, Fts5Tokenizer **ppOut);
+  void (*xDelete)(Fts5Tokenizer*);
+  int (*xTokenize)(Fts5Tokenizer*, 
+      void *pCtx,
+      int flags,            /* Mask of FTS5_TOKENIZE_* flags */
+      const char *pText, int nText, 
+      int (*xToken)(
+        void *pCtx,         /* Copy of 2nd argument to xTokenize() */
+        int tflags,         /* Mask of FTS5_TOKEN_* flags */
+        const char *pToken, /* Pointer to buffer containing token */
+        int nToken,         /* Size of token in bytes */
+        int iStart,         /* Byte offset of token within input text */
+        int iEnd            /* Byte offset of end of token within input text */
+      )
+  );
+};
+
+/* Flags that may be passed as the third argument to xTokenize() */
+#define FTS5_TOKENIZE_QUERY     0x0001
+#define FTS5_TOKENIZE_PREFIX    0x0002
+#define FTS5_TOKENIZE_DOCUMENT  0x0004
+#define FTS5_TOKENIZE_AUX       0x0008
+
+/* Flags that may be passed by the tokenizer implementation back to FTS5
+** as the third argument to the supplied xToken callback. */
+#define FTS5_TOKEN_COLOCATED    0x0001      /* Same position as prev. token */
+
+/*
+** END OF CUSTOM TOKENIZERS
+*************************************************************************/
+
+/*************************************************************************
+** FTS5 EXTENSION REGISTRATION API
+*/
+typedef struct fts5_api fts5_api;
+struct fts5_api {
+  int iVersion;                   /* Currently always set to 2 */
+
+  /* Create a new tokenizer */
+  int (*xCreateTokenizer)(
+    fts5_api *pApi,
+    const char *zName,
+    void *pContext,
+    fts5_tokenizer *pTokenizer,
+    void (*xDestroy)(void*)
+  );
+
+  /* Find an existing tokenizer */
+  int (*xFindTokenizer)(
+    fts5_api *pApi,
+    const char *zName,
+    void **ppContext,
+    fts5_tokenizer *pTokenizer
+  );
+
+  /* Create a new auxiliary function */
+  int (*xCreateFunction)(
+    fts5_api *pApi,
+    const char *zName,
+    void *pContext,
+    fts5_extension_function xFunction,
+    void (*xDestroy)(void*)
+  );
+};
+
+/*
+** END OF REGISTRATION API
+*************************************************************************/
+
+#ifdef __cplusplus
+}  /* end of the 'extern "C"' block */
+#endif
+
+#endif /* _FTS5_H */
+
+/******** End of fts5.h *********/
diff --git a/libs/tdlib/td/sqlite/sqlite/sqlite3ext.h b/libs/tdlib/td/sqlite/sqlite/sqlite3ext.h
new file mode 100644
index 0000000000..ce87e74690
--- /dev/null
+++ b/libs/tdlib/td/sqlite/sqlite/sqlite3ext.h
@@ -0,0 +1,560 @@
+/*
+** 2006 June 7
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This header file defines the SQLite interface for use by
+** shared libraries that want to be imported as extensions into
+** an SQLite instance.  Shared libraries that intend to be loaded
+** as extensions by SQLite should #include this file instead of 
+** sqlite3.h.
+*/
+#ifndef SQLITE3EXT_H
+#define SQLITE3EXT_H
+#include "sqlite3.h"
+
+/*
+** The following structure holds pointers to all of the SQLite API
+** routines.
+**
+** WARNING:  In order to maintain backwards compatibility, add new
+** interfaces to the end of this structure only.  If you insert new
+** interfaces in the middle of this structure, then older different
+** versions of SQLite will not be able to load each other's shared
+** libraries!
+*/
+struct sqlite3_api_routines {
+  void * (*aggregate_context)(sqlite3_context*,int nBytes);
+  int  (*aggregate_count)(sqlite3_context*);
+  int  (*bind_blob)(sqlite3_stmt*,int,const void*,int n,void(*)(void*));
+  int  (*bind_double)(sqlite3_stmt*,int,double);
+  int  (*bind_int)(sqlite3_stmt*,int,int);
+  int  (*bind_int64)(sqlite3_stmt*,int,sqlite_int64);
+  int  (*bind_null)(sqlite3_stmt*,int);
+  int  (*bind_parameter_count)(sqlite3_stmt*);
+  int  (*bind_parameter_index)(sqlite3_stmt*,const char*zName);
+  const char * (*bind_parameter_name)(sqlite3_stmt*,int);
+  int  (*bind_text)(sqlite3_stmt*,int,const char*,int n,void(*)(void*));
+  int  (*bind_text16)(sqlite3_stmt*,int,const void*,int,void(*)(void*));
+  int  (*bind_value)(sqlite3_stmt*,int,const sqlite3_value*);
+  int  (*busy_handler)(sqlite3*,int(*)(void*,int),void*);
+  int  (*busy_timeout)(sqlite3*,int ms);
+  int  (*changes)(sqlite3*);
+  int  (*close)(sqlite3*);
+  int  (*collation_needed)(sqlite3*,void*,void(*)(void*,sqlite3*,
+                           int eTextRep,const char*));
+  int  (*collation_needed16)(sqlite3*,void*,void(*)(void*,sqlite3*,
+                             int eTextRep,const void*));
+  const void * (*column_blob)(sqlite3_stmt*,int iCol);
+  int  (*column_bytes)(sqlite3_stmt*,int iCol);
+  int  (*column_bytes16)(sqlite3_stmt*,int iCol);
+  int  (*column_count)(sqlite3_stmt*pStmt);
+  const char * (*column_database_name)(sqlite3_stmt*,int);
+  const void * (*column_database_name16)(sqlite3_stmt*,int);
+  const char * (*column_decltype)(sqlite3_stmt*,int i);
+  const void * (*column_decltype16)(sqlite3_stmt*,int);
+  double  (*column_double)(sqlite3_stmt*,int iCol);
+  int  (*column_int)(sqlite3_stmt*,int iCol);
+  sqlite_int64  (*column_int64)(sqlite3_stmt*,int iCol);
+  const char * (*column_name)(sqlite3_stmt*,int);
+  const void * (*column_name16)(sqlite3_stmt*,int);
+  const char * (*column_origin_name)(sqlite3_stmt*,int);
+  const void * (*column_origin_name16)(sqlite3_stmt*,int);
+  const char * (*column_table_name)(sqlite3_stmt*,int);
+  const void * (*column_table_name16)(sqlite3_stmt*,int);
+  const unsigned char * (*column_text)(sqlite3_stmt*,int iCol);
+  const void * (*column_text16)(sqlite3_stmt*,int iCol);
+  int  (*column_type)(sqlite3_stmt*,int iCol);
+  sqlite3_value* (*column_value)(sqlite3_stmt*,int iCol);
+  void * (*commit_hook)(sqlite3*,int(*)(void*),void*);
+  int  (*complete)(const char*sql);
+  int  (*complete16)(const void*sql);
+  int  (*create_collation)(sqlite3*,const char*,int,void*,
+                           int(*)(void*,int,const void*,int,const void*));
+  int  (*create_collation16)(sqlite3*,const void*,int,void*,
+                             int(*)(void*,int,const void*,int,const void*));
+  int  (*create_function)(sqlite3*,const char*,int,int,void*,
+                          void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
+                          void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+                          void (*xFinal)(sqlite3_context*));
+  int  (*create_function16)(sqlite3*,const void*,int,int,void*,
+                            void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
+                            void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+                            void (*xFinal)(sqlite3_context*));
+  int (*create_module)(sqlite3*,const char*,const sqlite3_module*,void*);
+  int  (*data_count)(sqlite3_stmt*pStmt);
+  sqlite3 * (*db_handle)(sqlite3_stmt*);
+  int (*declare_vtab)(sqlite3*,const char*);
+  int  (*enable_shared_cache)(int);
+  int  (*errcode)(sqlite3*db);
+  const char * (*errmsg)(sqlite3*);
+  const void * (*errmsg16)(sqlite3*);
+  int  (*exec)(sqlite3*,const char*,sqlite3_callback,void*,char**);
+  int  (*expired)(sqlite3_stmt*);
+  int  (*finalize)(sqlite3_stmt*pStmt);
+  void  (*free)(void*);
+  void  (*free_table)(char**result);
+  int  (*get_autocommit)(sqlite3*);
+  void * (*get_auxdata)(sqlite3_context*,int);
+  int  (*get_table)(sqlite3*,const char*,char***,int*,int*,char**);
+  int  (*global_recover)(void);
+  void  (*interruptx)(sqlite3*);
+  sqlite_int64  (*last_insert_rowid)(sqlite3*);
+  const char * (*libversion)(void);
+  int  (*libversion_number)(void);
+  void *(*malloc)(int);
+  char * (*mprintf)(const char*,...);
+  int  (*open)(const char*,sqlite3**);
+  int  (*open16)(const void*,sqlite3**);
+  int  (*prepare)(sqlite3*,const char*,int,sqlite3_stmt**,const char**);
+  int  (*prepare16)(sqlite3*,const void*,int,sqlite3_stmt**,const void**);
+  void * (*profile)(sqlite3*,void(*)(void*,const char*,sqlite_uint64),void*);
+  void  (*progress_handler)(sqlite3*,int,int(*)(void*),void*);
+  void *(*realloc)(void*,int);
+  int  (*reset)(sqlite3_stmt*pStmt);
+  void  (*result_blob)(sqlite3_context*,const void*,int,void(*)(void*));
+  void  (*result_double)(sqlite3_context*,double);
+  void  (*result_error)(sqlite3_context*,const char*,int);
+  void  (*result_error16)(sqlite3_context*,const void*,int);
+  void  (*result_int)(sqlite3_context*,int);
+  void  (*result_int64)(sqlite3_context*,sqlite_int64);
+  void  (*result_null)(sqlite3_context*);
+  void  (*result_text)(sqlite3_context*,const char*,int,void(*)(void*));
+  void  (*result_text16)(sqlite3_context*,const void*,int,void(*)(void*));
+  void  (*result_text16be)(sqlite3_context*,const void*,int,void(*)(void*));
+  void  (*result_text16le)(sqlite3_context*,const void*,int,void(*)(void*));
+  void  (*result_value)(sqlite3_context*,sqlite3_value*);
+  void * (*rollback_hook)(sqlite3*,void(*)(void*),void*);
+  int  (*set_authorizer)(sqlite3*,int(*)(void*,int,const char*,const char*,
+                         const char*,const char*),void*);
+  void  (*set_auxdata)(sqlite3_context*,int,void*,void (*)(void*));
+  char * (*snprintf)(int,char*,const char*,...);
+  int  (*step)(sqlite3_stmt*);
+  int  (*table_column_metadata)(sqlite3*,const char*,const char*,const char*,
+                                char const**,char const**,int*,int*,int*);
+  void  (*thread_cleanup)(void);
+  int  (*total_changes)(sqlite3*);
+  void * (*trace)(sqlite3*,void(*xTrace)(void*,const char*),void*);
+  int  (*transfer_bindings)(sqlite3_stmt*,sqlite3_stmt*);
+  void * (*update_hook)(sqlite3*,void(*)(void*,int ,char const*,char const*,
+                                         sqlite_int64),void*);
+  void * (*user_data)(sqlite3_context*);
+  const void * (*value_blob)(sqlite3_value*);
+  int  (*value_bytes)(sqlite3_value*);
+  int  (*value_bytes16)(sqlite3_value*);
+  double  (*value_double)(sqlite3_value*);
+  int  (*value_int)(sqlite3_value*);
+  sqlite_int64  (*value_int64)(sqlite3_value*);
+  int  (*value_numeric_type)(sqlite3_value*);
+  const unsigned char * (*value_text)(sqlite3_value*);
+  const void * (*value_text16)(sqlite3_value*);
+  const void * (*value_text16be)(sqlite3_value*);
+  const void * (*value_text16le)(sqlite3_value*);
+  int  (*value_type)(sqlite3_value*);
+  char *(*vmprintf)(const char*,va_list);
+  /* Added ??? */
+  int (*overload_function)(sqlite3*, const char *zFuncName, int nArg);
+  /* Added by 3.3.13 */
+  int (*prepare_v2)(sqlite3*,const char*,int,sqlite3_stmt**,const char**);
+  int (*prepare16_v2)(sqlite3*,const void*,int,sqlite3_stmt**,const void**);
+  int (*clear_bindings)(sqlite3_stmt*);
+  /* Added by 3.4.1 */
+  int (*create_module_v2)(sqlite3*,const char*,const sqlite3_module*,void*,
+                          void (*xDestroy)(void *));
+  /* Added by 3.5.0 */
+  int (*bind_zeroblob)(sqlite3_stmt*,int,int);
+  int (*blob_bytes)(sqlite3_blob*);
+  int (*blob_close)(sqlite3_blob*);
+  int (*blob_open)(sqlite3*,const char*,const char*,const char*,sqlite3_int64,
+                   int,sqlite3_blob**);
+  int (*blob_read)(sqlite3_blob*,void*,int,int);
+  int (*blob_write)(sqlite3_blob*,const void*,int,int);
+  int (*create_collation_v2)(sqlite3*,const char*,int,void*,
+                             int(*)(void*,int,const void*,int,const void*),
+                             void(*)(void*));
+  int (*file_control)(sqlite3*,const char*,int,void*);
+  sqlite3_int64 (*memory_highwater)(int);
+  sqlite3_int64 (*memory_used)(void);
+  sqlite3_mutex *(*mutex_alloc)(int);
+  void (*mutex_enter)(sqlite3_mutex*);
+  void (*mutex_free)(sqlite3_mutex*);
+  void (*mutex_leave)(sqlite3_mutex*);
+  int (*mutex_try)(sqlite3_mutex*);
+  int (*open_v2)(const char*,sqlite3**,int,const char*);
+  int (*release_memory)(int);
+  void (*result_error_nomem)(sqlite3_context*);
+  void (*result_error_toobig)(sqlite3_context*);
+  int (*sleep)(int);
+  void (*soft_heap_limit)(int);
+  sqlite3_vfs *(*vfs_find)(const char*);
+  int (*vfs_register)(sqlite3_vfs*,int);
+  int (*vfs_unregister)(sqlite3_vfs*);
+  int (*xthreadsafe)(void);
+  void (*result_zeroblob)(sqlite3_context*,int);
+  void (*result_error_code)(sqlite3_context*,int);
+  int (*test_control)(int, ...);
+  void (*randomness)(int,void*);
+  sqlite3 *(*context_db_handle)(sqlite3_context*);
+  int (*extended_result_codes)(sqlite3*,int);
+  int (*limit)(sqlite3*,int,int);
+  sqlite3_stmt *(*next_stmt)(sqlite3*,sqlite3_stmt*);
+  const char *(*sql)(sqlite3_stmt*);
+  int (*status)(int,int*,int*,int);
+  int (*backup_finish)(sqlite3_backup*);
+  sqlite3_backup *(*backup_init)(sqlite3*,const char*,sqlite3*,const char*);
+  int (*backup_pagecount)(sqlite3_backup*);
+  int (*backup_remaining)(sqlite3_backup*);
+  int (*backup_step)(sqlite3_backup*,int);
+  const char *(*compileoption_get)(int);
+  int (*compileoption_used)(const char*);
+  int (*create_function_v2)(sqlite3*,const char*,int,int,void*,
+                            void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
+                            void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+                            void (*xFinal)(sqlite3_context*),
+                            void(*xDestroy)(void*));
+  int (*db_config)(sqlite3*,int,...);
+  sqlite3_mutex *(*db_mutex)(sqlite3*);
+  int (*db_status)(sqlite3*,int,int*,int*,int);
+  int (*extended_errcode)(sqlite3*);
+  void (*log)(int,const char*,...);
+  sqlite3_int64 (*soft_heap_limit64)(sqlite3_int64);
+  const char *(*sourceid)(void);
+  int (*stmt_status)(sqlite3_stmt*,int,int);
+  int (*strnicmp)(const char*,const char*,int);
+  int (*unlock_notify)(sqlite3*,void(*)(void**,int),void*);
+  int (*wal_autocheckpoint)(sqlite3*,int);
+  int (*wal_checkpoint)(sqlite3*,const char*);
+  void *(*wal_hook)(sqlite3*,int(*)(void*,sqlite3*,const char*,int),void*);
+  int (*blob_reopen)(sqlite3_blob*,sqlite3_int64);
+  int (*vtab_config)(sqlite3*,int op,...);
+  int (*vtab_on_conflict)(sqlite3*);
+  /* Version 3.7.16 and later */
+  int (*close_v2)(sqlite3*);
+  const char *(*db_filename)(sqlite3*,const char*);
+  int (*db_readonly)(sqlite3*,const char*);
+  int (*db_release_memory)(sqlite3*);
+  const char *(*errstr)(int);
+  int (*stmt_busy)(sqlite3_stmt*);
+  int (*stmt_readonly)(sqlite3_stmt*);
+  int (*stricmp)(const char*,const char*);
+  int (*uri_boolean)(const char*,const char*,int);
+  sqlite3_int64 (*uri_int64)(const char*,const char*,sqlite3_int64);
+  const char *(*uri_parameter)(const char*,const char*);
+  char *(*vsnprintf)(int,char*,const char*,va_list);
+  int (*wal_checkpoint_v2)(sqlite3*,const char*,int,int*,int*);
+  /* Version 3.8.7 and later */
+  int (*auto_extension)(void(*)(void));
+  int (*bind_blob64)(sqlite3_stmt*,int,const void*,sqlite3_uint64,
+                     void(*)(void*));
+  int (*bind_text64)(sqlite3_stmt*,int,const char*,sqlite3_uint64,
+                      void(*)(void*),unsigned char);
+  int (*cancel_auto_extension)(void(*)(void));
+  int (*load_extension)(sqlite3*,const char*,const char*,char**);
+  void *(*malloc64)(sqlite3_uint64);
+  sqlite3_uint64 (*msize)(void*);
+  void *(*realloc64)(void*,sqlite3_uint64);
+  void (*reset_auto_extension)(void);
+  void (*result_blob64)(sqlite3_context*,const void*,sqlite3_uint64,
+                        void(*)(void*));
+  void (*result_text64)(sqlite3_context*,const char*,sqlite3_uint64,
+                         void(*)(void*), unsigned char);
+  int (*strglob)(const char*,const char*);
+  /* Version 3.8.11 and later */
+  sqlite3_value *(*value_dup)(const sqlite3_value*);
+  void (*value_free)(sqlite3_value*);
+  int (*result_zeroblob64)(sqlite3_context*,sqlite3_uint64);
+  int (*bind_zeroblob64)(sqlite3_stmt*, int, sqlite3_uint64);
+  /* Version 3.9.0 and later */
+  unsigned int (*value_subtype)(sqlite3_value*);
+  void (*result_subtype)(sqlite3_context*,unsigned int);
+  /* Version 3.10.0 and later */
+  int (*status64)(int,sqlite3_int64*,sqlite3_int64*,int);
+  int (*strlike)(const char*,const char*,unsigned int);
+  int (*db_cacheflush)(sqlite3*);
+  /* Version 3.12.0 and later */
+  int (*system_errno)(sqlite3*);
+  /* Version 3.14.0 and later */
+  int (*trace_v2)(sqlite3*,unsigned,int(*)(unsigned,void*,void*,void*),void*);
+  char *(*expanded_sql)(sqlite3_stmt*);
+};
+
+/*
+** This is the function signature used for all extension entry points.  It
+** is also defined in the file "loadext.c".
+*/
+typedef int (*sqlite3_loadext_entry)(
+  sqlite3 *db,                       /* Handle to the database. */
+  char **pzErrMsg,                   /* Used to set error string on failure. */
+  const sqlite3_api_routines *pThunk /* Extension API function pointers. */
+);
+
+/*
+** The following macros redefine the API routines so that they are
+** redirected through the global sqlite3_api structure.
+**
+** This header file is also used by the loadext.c source file
+** (part of the main SQLite library - not an extension) so that
+** it can get access to the sqlite3_api_routines structure
+** definition.  But the main library does not want to redefine
+** the API.  So the redefinition macros are only valid if the
+** SQLITE_CORE macros is undefined.
+*/
+#if !defined(SQLITE_CORE) && !defined(SQLITE_OMIT_LOAD_EXTENSION)
+#define sqlite3_aggregate_context      sqlite3_api->aggregate_context
+#ifndef SQLITE_OMIT_DEPRECATED
+#define sqlite3_aggregate_count        sqlite3_api->aggregate_count
+#endif
+#define sqlite3_bind_blob              sqlite3_api->bind_blob
+#define sqlite3_bind_double            sqlite3_api->bind_double
+#define sqlite3_bind_int               sqlite3_api->bind_int
+#define sqlite3_bind_int64             sqlite3_api->bind_int64
+#define sqlite3_bind_null              sqlite3_api->bind_null
+#define sqlite3_bind_parameter_count   sqlite3_api->bind_parameter_count
+#define sqlite3_bind_parameter_index   sqlite3_api->bind_parameter_index
+#define sqlite3_bind_parameter_name    sqlite3_api->bind_parameter_name
+#define sqlite3_bind_text              sqlite3_api->bind_text
+#define sqlite3_bind_text16            sqlite3_api->bind_text16
+#define sqlite3_bind_value             sqlite3_api->bind_value
+#define sqlite3_busy_handler           sqlite3_api->busy_handler
+#define sqlite3_busy_timeout           sqlite3_api->busy_timeout
+#define sqlite3_changes                sqlite3_api->changes
+#define sqlite3_close                  sqlite3_api->close
+#define sqlite3_collation_needed       sqlite3_api->collation_needed
+#define sqlite3_collation_needed16     sqlite3_api->collation_needed16
+#define sqlite3_column_blob            sqlite3_api->column_blob
+#define sqlite3_column_bytes           sqlite3_api->column_bytes
+#define sqlite3_column_bytes16         sqlite3_api->column_bytes16
+#define sqlite3_column_count           sqlite3_api->column_count
+#define sqlite3_column_database_name   sqlite3_api->column_database_name
+#define sqlite3_column_database_name16 sqlite3_api->column_database_name16
+#define sqlite3_column_decltype        sqlite3_api->column_decltype
+#define sqlite3_column_decltype16      sqlite3_api->column_decltype16
+#define sqlite3_column_double          sqlite3_api->column_double
+#define sqlite3_column_int             sqlite3_api->column_int
+#define sqlite3_column_int64           sqlite3_api->column_int64
+#define sqlite3_column_name            sqlite3_api->column_name
+#define sqlite3_column_name16          sqlite3_api->column_name16
+#define sqlite3_column_origin_name     sqlite3_api->column_origin_name
+#define sqlite3_column_origin_name16   sqlite3_api->column_origin_name16
+#define sqlite3_column_table_name      sqlite3_api->column_table_name
+#define sqlite3_column_table_name16    sqlite3_api->column_table_name16
+#define sqlite3_column_text            sqlite3_api->column_text
+#define sqlite3_column_text16          sqlite3_api->column_text16
+#define sqlite3_column_type            sqlite3_api->column_type
+#define sqlite3_column_value           sqlite3_api->column_value
+#define sqlite3_commit_hook            sqlite3_api->commit_hook
+#define sqlite3_complete               sqlite3_api->complete
+#define sqlite3_complete16             sqlite3_api->complete16
+#define sqlite3_create_collation       sqlite3_api->create_collation
+#define sqlite3_create_collation16     sqlite3_api->create_collation16
+#define sqlite3_create_function        sqlite3_api->create_function
+#define sqlite3_create_function16      sqlite3_api->create_function16
+#define sqlite3_create_module          sqlite3_api->create_module
+#define sqlite3_create_module_v2       sqlite3_api->create_module_v2
+#define sqlite3_data_count             sqlite3_api->data_count
+#define sqlite3_db_handle              sqlite3_api->db_handle
+#define sqlite3_declare_vtab           sqlite3_api->declare_vtab
+#define sqlite3_enable_shared_cache    sqlite3_api->enable_shared_cache
+#define sqlite3_errcode                sqlite3_api->errcode
+#define sqlite3_errmsg                 sqlite3_api->errmsg
+#define sqlite3_errmsg16               sqlite3_api->errmsg16
+#define sqlite3_exec                   sqlite3_api->exec
+#ifndef SQLITE_OMIT_DEPRECATED
+#define sqlite3_expired                sqlite3_api->expired
+#endif
+#define sqlite3_finalize               sqlite3_api->finalize
+#define sqlite3_free                   sqlite3_api->free
+#define sqlite3_free_table             sqlite3_api->free_table
+#define sqlite3_get_autocommit         sqlite3_api->get_autocommit
+#define sqlite3_get_auxdata            sqlite3_api->get_auxdata
+#define sqlite3_get_table              sqlite3_api->get_table
+#ifndef SQLITE_OMIT_DEPRECATED
+#define sqlite3_global_recover         sqlite3_api->global_recover
+#endif
+#define sqlite3_interrupt              sqlite3_api->interruptx
+#define sqlite3_last_insert_rowid      sqlite3_api->last_insert_rowid
+#define sqlite3_libversion             sqlite3_api->libversion
+#define sqlite3_libversion_number      sqlite3_api->libversion_number
+#define sqlite3_malloc                 sqlite3_api->malloc
+#define sqlite3_mprintf                sqlite3_api->mprintf
+#define sqlite3_open                   sqlite3_api->open
+#define sqlite3_open16                 sqlite3_api->open16
+#define sqlite3_prepare                sqlite3_api->prepare
+#define sqlite3_prepare16              sqlite3_api->prepare16
+#define sqlite3_prepare_v2             sqlite3_api->prepare_v2
+#define sqlite3_prepare16_v2           sqlite3_api->prepare16_v2
+#define sqlite3_profile                sqlite3_api->profile
+#define sqlite3_progress_handler       sqlite3_api->progress_handler
+#define sqlite3_realloc                sqlite3_api->realloc
+#define sqlite3_reset                  sqlite3_api->reset
+#define sqlite3_result_blob            sqlite3_api->result_blob
+#define sqlite3_result_double          sqlite3_api->result_double
+#define sqlite3_result_error           sqlite3_api->result_error
+#define sqlite3_result_error16         sqlite3_api->result_error16
+#define sqlite3_result_int             sqlite3_api->result_int
+#define sqlite3_result_int64           sqlite3_api->result_int64
+#define sqlite3_result_null            sqlite3_api->result_null
+#define sqlite3_result_text            sqlite3_api->result_text
+#define sqlite3_result_text16          sqlite3_api->result_text16
+#define sqlite3_result_text16be        sqlite3_api->result_text16be
+#define sqlite3_result_text16le        sqlite3_api->result_text16le
+#define sqlite3_result_value           sqlite3_api->result_value
+#define sqlite3_rollback_hook          sqlite3_api->rollback_hook
+#define sqlite3_set_authorizer         sqlite3_api->set_authorizer
+#define sqlite3_set_auxdata            sqlite3_api->set_auxdata
+#define sqlite3_snprintf               sqlite3_api->snprintf
+#define sqlite3_step                   sqlite3_api->step
+#define sqlite3_table_column_metadata  sqlite3_api->table_column_metadata
+#define sqlite3_thread_cleanup         sqlite3_api->thread_cleanup
+#define sqlite3_total_changes          sqlite3_api->total_changes
+#define sqlite3_trace                  sqlite3_api->trace
+#ifndef SQLITE_OMIT_DEPRECATED
+#define sqlite3_transfer_bindings      sqlite3_api->transfer_bindings
+#endif
+#define sqlite3_update_hook            sqlite3_api->update_hook
+#define sqlite3_user_data              sqlite3_api->user_data
+#define sqlite3_value_blob             sqlite3_api->value_blob
+#define sqlite3_value_bytes            sqlite3_api->value_bytes
+#define sqlite3_value_bytes16          sqlite3_api->value_bytes16
+#define sqlite3_value_double           sqlite3_api->value_double
+#define sqlite3_value_int              sqlite3_api->value_int
+#define sqlite3_value_int64            sqlite3_api->value_int64
+#define sqlite3_value_numeric_type     sqlite3_api->value_numeric_type
+#define sqlite3_value_text             sqlite3_api->value_text
+#define sqlite3_value_text16           sqlite3_api->value_text16
+#define sqlite3_value_text16be         sqlite3_api->value_text16be
+#define sqlite3_value_text16le         sqlite3_api->value_text16le
+#define sqlite3_value_type             sqlite3_api->value_type
+#define sqlite3_vmprintf               sqlite3_api->vmprintf
+#define sqlite3_vsnprintf              sqlite3_api->vsnprintf
+#define sqlite3_overload_function      sqlite3_api->overload_function
+#define sqlite3_prepare_v2             sqlite3_api->prepare_v2
+#define sqlite3_prepare16_v2           sqlite3_api->prepare16_v2
+#define sqlite3_clear_bindings         sqlite3_api->clear_bindings
+#define sqlite3_bind_zeroblob          sqlite3_api->bind_zeroblob
+#define sqlite3_blob_bytes             sqlite3_api->blob_bytes
+#define sqlite3_blob_close             sqlite3_api->blob_close
+#define sqlite3_blob_open              sqlite3_api->blob_open
+#define sqlite3_blob_read              sqlite3_api->blob_read
+#define sqlite3_blob_write             sqlite3_api->blob_write
+#define sqlite3_create_collation_v2    sqlite3_api->create_collation_v2
+#define sqlite3_file_control           sqlite3_api->file_control
+#define sqlite3_memory_highwater       sqlite3_api->memory_highwater
+#define sqlite3_memory_used            sqlite3_api->memory_used
+#define sqlite3_mutex_alloc            sqlite3_api->mutex_alloc
+#define sqlite3_mutex_enter            sqlite3_api->mutex_enter
+#define sqlite3_mutex_free             sqlite3_api->mutex_free
+#define sqlite3_mutex_leave            sqlite3_api->mutex_leave
+#define sqlite3_mutex_try              sqlite3_api->mutex_try
+#define sqlite3_open_v2                sqlite3_api->open_v2
+#define sqlite3_release_memory         sqlite3_api->release_memory
+#define sqlite3_result_error_nomem     sqlite3_api->result_error_nomem
+#define sqlite3_result_error_toobig    sqlite3_api->result_error_toobig
+#define sqlite3_sleep                  sqlite3_api->sleep
+#define sqlite3_soft_heap_limit        sqlite3_api->soft_heap_limit
+#define sqlite3_vfs_find               sqlite3_api->vfs_find
+#define sqlite3_vfs_register           sqlite3_api->vfs_register
+#define sqlite3_vfs_unregister         sqlite3_api->vfs_unregister
+#define sqlite3_threadsafe             sqlite3_api->xthreadsafe
+#define sqlite3_result_zeroblob        sqlite3_api->result_zeroblob
+#define sqlite3_result_error_code      sqlite3_api->result_error_code
+#define sqlite3_test_control           sqlite3_api->test_control
+#define sqlite3_randomness             sqlite3_api->randomness
+#define sqlite3_context_db_handle      sqlite3_api->context_db_handle
+#define sqlite3_extended_result_codes  sqlite3_api->extended_result_codes
+#define sqlite3_limit                  sqlite3_api->limit
+#define sqlite3_next_stmt              sqlite3_api->next_stmt
+#define sqlite3_sql                    sqlite3_api->sql
+#define sqlite3_status                 sqlite3_api->status
+#define sqlite3_backup_finish          sqlite3_api->backup_finish
+#define sqlite3_backup_init            sqlite3_api->backup_init
+#define sqlite3_backup_pagecount       sqlite3_api->backup_pagecount
+#define sqlite3_backup_remaining       sqlite3_api->backup_remaining
+#define sqlite3_backup_step            sqlite3_api->backup_step
+#define sqlite3_compileoption_get      sqlite3_api->compileoption_get
+#define sqlite3_compileoption_used     sqlite3_api->compileoption_used
+#define sqlite3_create_function_v2     sqlite3_api->create_function_v2
+#define sqlite3_db_config              sqlite3_api->db_config
+#define sqlite3_db_mutex               sqlite3_api->db_mutex
+#define sqlite3_db_status              sqlite3_api->db_status
+#define sqlite3_extended_errcode       sqlite3_api->extended_errcode
+#define sqlite3_log                    sqlite3_api->log
+#define sqlite3_soft_heap_limit64      sqlite3_api->soft_heap_limit64
+#define sqlite3_sourceid               sqlite3_api->sourceid
+#define sqlite3_stmt_status            sqlite3_api->stmt_status
+#define sqlite3_strnicmp               sqlite3_api->strnicmp
+#define sqlite3_unlock_notify          sqlite3_api->unlock_notify
+#define sqlite3_wal_autocheckpoint     sqlite3_api->wal_autocheckpoint
+#define sqlite3_wal_checkpoint         sqlite3_api->wal_checkpoint
+#define sqlite3_wal_hook               sqlite3_api->wal_hook
+#define sqlite3_blob_reopen            sqlite3_api->blob_reopen
+#define sqlite3_vtab_config            sqlite3_api->vtab_config
+#define sqlite3_vtab_on_conflict       sqlite3_api->vtab_on_conflict
+/* Version 3.7.16 and later */
+#define sqlite3_close_v2               sqlite3_api->close_v2
+#define sqlite3_db_filename            sqlite3_api->db_filename
+#define sqlite3_db_readonly            sqlite3_api->db_readonly
+#define sqlite3_db_release_memory      sqlite3_api->db_release_memory
+#define sqlite3_errstr                 sqlite3_api->errstr
+#define sqlite3_stmt_busy              sqlite3_api->stmt_busy
+#define sqlite3_stmt_readonly          sqlite3_api->stmt_readonly
+#define sqlite3_stricmp                sqlite3_api->stricmp
+#define sqlite3_uri_boolean            sqlite3_api->uri_boolean
+#define sqlite3_uri_int64              sqlite3_api->uri_int64
+#define sqlite3_uri_parameter          sqlite3_api->uri_parameter
+#define sqlite3_uri_vsnprintf          sqlite3_api->vsnprintf
+#define sqlite3_wal_checkpoint_v2      sqlite3_api->wal_checkpoint_v2
+/* Version 3.8.7 and later */
+#define sqlite3_auto_extension         sqlite3_api->auto_extension
+#define sqlite3_bind_blob64            sqlite3_api->bind_blob64
+#define sqlite3_bind_text64            sqlite3_api->bind_text64
+#define sqlite3_cancel_auto_extension  sqlite3_api->cancel_auto_extension
+#define sqlite3_load_extension         sqlite3_api->load_extension
+#define sqlite3_malloc64               sqlite3_api->malloc64
+#define sqlite3_msize                  sqlite3_api->msize
+#define sqlite3_realloc64              sqlite3_api->realloc64
+#define sqlite3_reset_auto_extension   sqlite3_api->reset_auto_extension
+#define sqlite3_result_blob64          sqlite3_api->result_blob64
+#define sqlite3_result_text64          sqlite3_api->result_text64
+#define sqlite3_strglob                sqlite3_api->strglob
+/* Version 3.8.11 and later */
+#define sqlite3_value_dup              sqlite3_api->value_dup
+#define sqlite3_value_free             sqlite3_api->value_free
+#define sqlite3_result_zeroblob64      sqlite3_api->result_zeroblob64
+#define sqlite3_bind_zeroblob64        sqlite3_api->bind_zeroblob64
+/* Version 3.9.0 and later */
+#define sqlite3_value_subtype          sqlite3_api->value_subtype
+#define sqlite3_result_subtype         sqlite3_api->result_subtype
+/* Version 3.10.0 and later */
+#define sqlite3_status64               sqlite3_api->status64
+#define sqlite3_strlike                sqlite3_api->strlike
+#define sqlite3_db_cacheflush          sqlite3_api->db_cacheflush
+/* Version 3.12.0 and later */
+#define sqlite3_system_errno           sqlite3_api->system_errno
+/* Version 3.14.0 and later */
+#define sqlite3_trace_v2               sqlite3_api->trace_v2
+#define sqlite3_expanded_sql           sqlite3_api->expanded_sql
+#endif /* !defined(SQLITE_CORE) && !defined(SQLITE_OMIT_LOAD_EXTENSION) */
+
+#if !defined(SQLITE_CORE) && !defined(SQLITE_OMIT_LOAD_EXTENSION)
+  /* This case when the file really is being compiled as a loadable 
+  ** extension */
+# define SQLITE_EXTENSION_INIT1     const sqlite3_api_routines *sqlite3_api=0;
+# define SQLITE_EXTENSION_INIT2(v)  sqlite3_api=v;
+# define SQLITE_EXTENSION_INIT3     \
+    extern const sqlite3_api_routines *sqlite3_api;
+#else
+  /* This case when the file is being statically linked into the 
+  ** application */
+# define SQLITE_EXTENSION_INIT1     /*no-op*/
+# define SQLITE_EXTENSION_INIT2(v)  (void)v; /* unused parameter */
+# define SQLITE_EXTENSION_INIT3     /*no-op*/
+#endif
+
+#endif /* SQLITE3EXT_H */
diff --git a/libs/tdlib/td/sqlite/sqlite/sqlite3session.h b/libs/tdlib/td/sqlite/sqlite/sqlite3session.h
new file mode 100644
index 0000000000..d9f806e54f
--- /dev/null
+++ b/libs/tdlib/td/sqlite/sqlite/sqlite3session.h
@@ -0,0 +1,1280 @@
+#if !defined(__SQLITESESSION_H_) && defined(SQLITE_ENABLE_SESSION)
+#define __SQLITESESSION_H_ 1
+
+/*
+** Make sure we can call this stuff from C++.
+*/
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "sqlite3.h"
+
+/*
+** CAPI3REF: Session Object Handle
+*/
+typedef struct sqlite3_session sqlite3_session;
+
+/*
+** CAPI3REF: Changeset Iterator Handle
+*/
+typedef struct sqlite3_changeset_iter sqlite3_changeset_iter;
+
+/*
+** CAPI3REF: Create A New Session Object
+**
+** Create a new session object attached to database handle db. If successful,
+** a pointer to the new object is written to *ppSession and SQLITE_OK is
+** returned. If an error occurs, *ppSession is set to NULL and an SQLite
+** error code (e.g. SQLITE_NOMEM) is returned.
+**
+** It is possible to create multiple session objects attached to a single
+** database handle.
+**
+** Session objects created using this function should be deleted using the
+** [sqlite3session_delete()] function before the database handle that they
+** are attached to is itself closed. If the database handle is closed before
+** the session object is deleted, then the results of calling any session
+** module function, including [sqlite3session_delete()] on the session object
+** are undefined.
+**
+** Because the session module uses the [sqlite3_preupdate_hook()] API, it
+** is not possible for an application to register a pre-update hook on a
+** database handle that has one or more session objects attached. Nor is
+** it possible to create a session object attached to a database handle for
+** which a pre-update hook is already defined. The results of attempting 
+** either of these things are undefined.
+**
+** The session object will be used to create changesets for tables in
+** database zDb, where zDb is either "main", or "temp", or the name of an
+** attached database. It is not an error if database zDb is not attached
+** to the database when the session object is created.
+*/
+int sqlite3session_create(
+  sqlite3 *db,                    /* Database handle */
+  const char *zDb,                /* Name of db (e.g. "main") */
+  sqlite3_session **ppSession     /* OUT: New session object */
+);
+
+/*
+** CAPI3REF: Delete A Session Object
+**
+** Delete a session object previously allocated using 
+** [sqlite3session_create()]. Once a session object has been deleted, the
+** results of attempting to use pSession with any other session module
+** function are undefined.
+**
+** Session objects must be deleted before the database handle to which they
+** are attached is closed. Refer to the documentation for 
+** [sqlite3session_create()] for details.
+*/
+void sqlite3session_delete(sqlite3_session *pSession);
+
+
+/*
+** CAPI3REF: Enable Or Disable A Session Object
+**
+** Enable or disable the recording of changes by a session object. When
+** enabled, a session object records changes made to the database. When
+** disabled - it does not. A newly created session object is enabled.
+** Refer to the documentation for [sqlite3session_changeset()] for further
+** details regarding how enabling and disabling a session object affects
+** the eventual changesets.
+**
+** Passing zero to this function disables the session. Passing a value
+** greater than zero enables it. Passing a value less than zero is a 
+** no-op, and may be used to query the current state of the session.
+**
+** The return value indicates the final state of the session object: 0 if 
+** the session is disabled, or 1 if it is enabled.
+*/
+int sqlite3session_enable(sqlite3_session *pSession, int bEnable);
+
+/*
+** CAPI3REF: Set Or Clear the Indirect Change Flag
+**
+** Each change recorded by a session object is marked as either direct or
+** indirect. A change is marked as indirect if either:
+**
+** <ul>
+**   <li> The session object "indirect" flag is set when the change is
+**        made, or
+**   <li> The change is made by an SQL trigger or foreign key action 
+**        instead of directly as a result of a users SQL statement.
+** </ul>
+**
+** If a single row is affected by more than one operation within a session,
+** then the change is considered indirect if all operations meet the criteria
+** for an indirect change above, or direct otherwise.
+**
+** This function is used to set, clear or query the session object indirect
+** flag.  If the second argument passed to this function is zero, then the
+** indirect flag is cleared. If it is greater than zero, the indirect flag
+** is set. Passing a value less than zero does not modify the current value
+** of the indirect flag, and may be used to query the current state of the 
+** indirect flag for the specified session object.
+**
+** The return value indicates the final state of the indirect flag: 0 if 
+** it is clear, or 1 if it is set.
+*/
+int sqlite3session_indirect(sqlite3_session *pSession, int bIndirect);
+
+/*
+** CAPI3REF: Attach A Table To A Session Object
+**
+** If argument zTab is not NULL, then it is the name of a table to attach
+** to the session object passed as the first argument. All subsequent changes 
+** made to the table while the session object is enabled will be recorded. See 
+** documentation for [sqlite3session_changeset()] for further details.
+**
+** Or, if argument zTab is NULL, then changes are recorded for all tables
+** in the database. If additional tables are added to the database (by 
+** executing "CREATE TABLE" statements) after this call is made, changes for 
+** the new tables are also recorded.
+**
+** Changes can only be recorded for tables that have a PRIMARY KEY explicitly
+** defined as part of their CREATE TABLE statement. It does not matter if the 
+** PRIMARY KEY is an "INTEGER PRIMARY KEY" (rowid alias) or not. The PRIMARY
+** KEY may consist of a single column, or may be a composite key.
+** 
+** It is not an error if the named table does not exist in the database. Nor
+** is it an error if the named table does not have a PRIMARY KEY. However,
+** no changes will be recorded in either of these scenarios.
+**
+** Changes are not recorded for individual rows that have NULL values stored
+** in one or more of their PRIMARY KEY columns.
+**
+** SQLITE_OK is returned if the call completes without error. Or, if an error 
+** occurs, an SQLite error code (e.g. SQLITE_NOMEM) is returned.
+*/
+int sqlite3session_attach(
+  sqlite3_session *pSession,      /* Session object */
+  const char *zTab                /* Table name */
+);
+
+/*
+** CAPI3REF: Set a table filter on a Session Object.
+**
+** The second argument (xFilter) is the "filter callback". For changes to rows 
+** in tables that are not attached to the Session object, the filter is called
+** to determine whether changes to the table's rows should be tracked or not. 
+** If xFilter returns 0, changes is not tracked. Note that once a table is 
+** attached, xFilter will not be called again.
+*/
+void sqlite3session_table_filter(
+  sqlite3_session *pSession,      /* Session object */
+  int(*xFilter)(
+    void *pCtx,                   /* Copy of third arg to _filter_table() */
+    const char *zTab              /* Table name */
+  ),
+  void *pCtx                      /* First argument passed to xFilter */
+);
+
+/*
+** CAPI3REF: Generate A Changeset From A Session Object
+**
+** Obtain a changeset containing changes to the tables attached to the 
+** session object passed as the first argument. If successful, 
+** set *ppChangeset to point to a buffer containing the changeset 
+** and *pnChangeset to the size of the changeset in bytes before returning
+** SQLITE_OK. If an error occurs, set both *ppChangeset and *pnChangeset to
+** zero and return an SQLite error code.
+**
+** A changeset consists of zero or more INSERT, UPDATE and/or DELETE changes,
+** each representing a change to a single row of an attached table. An INSERT
+** change contains the values of each field of a new database row. A DELETE
+** contains the original values of each field of a deleted database row. An
+** UPDATE change contains the original values of each field of an updated
+** database row along with the updated values for each updated non-primary-key
+** column. It is not possible for an UPDATE change to represent a change that
+** modifies the values of primary key columns. If such a change is made, it
+** is represented in a changeset as a DELETE followed by an INSERT.
+**
+** Changes are not recorded for rows that have NULL values stored in one or 
+** more of their PRIMARY KEY columns. If such a row is inserted or deleted,
+** no corresponding change is present in the changesets returned by this
+** function. If an existing row with one or more NULL values stored in
+** PRIMARY KEY columns is updated so that all PRIMARY KEY columns are non-NULL,
+** only an INSERT is appears in the changeset. Similarly, if an existing row
+** with non-NULL PRIMARY KEY values is updated so that one or more of its
+** PRIMARY KEY columns are set to NULL, the resulting changeset contains a
+** DELETE change only.
+**
+** The contents of a changeset may be traversed using an iterator created
+** using the [sqlite3changeset_start()] API. A changeset may be applied to
+** a database with a compatible schema using the [sqlite3changeset_apply()]
+** API.
+**
+** Within a changeset generated by this function, all changes related to a
+** single table are grouped together. In other words, when iterating through
+** a changeset or when applying a changeset to a database, all changes related
+** to a single table are processed before moving on to the next table. Tables
+** are sorted in the same order in which they were attached (or auto-attached)
+** to the sqlite3_session object. The order in which the changes related to
+** a single table are stored is undefined.
+**
+** Following a successful call to this function, it is the responsibility of
+** the caller to eventually free the buffer that *ppChangeset points to using
+** [sqlite3_free()].
+**
+** <h3>Changeset Generation</h3>
+**
+** Once a table has been attached to a session object, the session object
+** records the primary key values of all new rows inserted into the table.
+** It also records the original primary key and other column values of any
+** deleted or updated rows. For each unique primary key value, data is only
+** recorded once - the first time a row with said primary key is inserted,
+** updated or deleted in the lifetime of the session.
+**
+** There is one exception to the previous paragraph: when a row is inserted,
+** updated or deleted, if one or more of its primary key columns contain a
+** NULL value, no record of the change is made.
+**
+** The session object therefore accumulates two types of records - those
+** that consist of primary key values only (created when the user inserts
+** a new record) and those that consist of the primary key values and the
+** original values of other table columns (created when the users deletes
+** or updates a record).
+**
+** When this function is called, the requested changeset is created using
+** both the accumulated records and the current contents of the database
+** file. Specifically:
+**
+** <ul>
+**   <li> For each record generated by an insert, the database is queried
+**        for a row with a matching primary key. If one is found, an INSERT
+**        change is added to the changeset. If no such row is found, no change 
+**        is added to the changeset.
+**
+**   <li> For each record generated by an update or delete, the database is 
+**        queried for a row with a matching primary key. If such a row is
+**        found and one or more of the non-primary key fields have been
+**        modified from their original values, an UPDATE change is added to 
+**        the changeset. Or, if no such row is found in the table, a DELETE 
+**        change is added to the changeset. If there is a row with a matching
+**        primary key in the database, but all fields contain their original
+**        values, no change is added to the changeset.
+** </ul>
+**
+** This means, amongst other things, that if a row is inserted and then later
+** deleted while a session object is active, neither the insert nor the delete
+** will be present in the changeset. Or if a row is deleted and then later a 
+** row with the same primary key values inserted while a session object is
+** active, the resulting changeset will contain an UPDATE change instead of
+** a DELETE and an INSERT.
+**
+** When a session object is disabled (see the [sqlite3session_enable()] API),
+** it does not accumulate records when rows are inserted, updated or deleted.
+** This may appear to have some counter-intuitive effects if a single row
+** is written to more than once during a session. For example, if a row
+** is inserted while a session object is enabled, then later deleted while 
+** the same session object is disabled, no INSERT record will appear in the
+** changeset, even though the delete took place while the session was disabled.
+** Or, if one field of a row is updated while a session is disabled, and 
+** another field of the same row is updated while the session is enabled, the
+** resulting changeset will contain an UPDATE change that updates both fields.
+*/
+int sqlite3session_changeset(
+  sqlite3_session *pSession,      /* Session object */
+  int *pnChangeset,               /* OUT: Size of buffer at *ppChangeset */
+  void **ppChangeset              /* OUT: Buffer containing changeset */
+);
+
+/*
+** CAPI3REF: Load The Difference Between Tables Into A Session 
+**
+** If it is not already attached to the session object passed as the first
+** argument, this function attaches table zTbl in the same manner as the
+** [sqlite3session_attach()] function. If zTbl does not exist, or if it
+** does not have a primary key, this function is a no-op (but does not return
+** an error).
+**
+** Argument zFromDb must be the name of a database ("main", "temp" etc.)
+** attached to the same database handle as the session object that contains 
+** a table compatible with the table attached to the session by this function.
+** A table is considered compatible if it:
+**
+** <ul>
+**   <li> Has the same name,
+**   <li> Has the same set of columns declared in the same order, and
+**   <li> Has the same PRIMARY KEY definition.
+** </ul>
+**
+** If the tables are not compatible, SQLITE_SCHEMA is returned. If the tables
+** are compatible but do not have any PRIMARY KEY columns, it is not an error
+** but no changes are added to the session object. As with other session
+** APIs, tables without PRIMARY KEYs are simply ignored.
+**
+** This function adds a set of changes to the session object that could be
+** used to update the table in database zFrom (call this the "from-table") 
+** so that its content is the same as the table attached to the session 
+** object (call this the "to-table"). Specifically:
+**
+** <ul>
+**   <li> For each row (primary key) that exists in the to-table but not in 
+**     the from-table, an INSERT record is added to the session object.
+**
+**   <li> For each row (primary key) that exists in the to-table but not in 
+**     the from-table, a DELETE record is added to the session object.
+**
+**   <li> For each row (primary key) that exists in both tables, but features 
+**     different in each, an UPDATE record is added to the session.
+** </ul>
+**
+** To clarify, if this function is called and then a changeset constructed
+** using [sqlite3session_changeset()], then after applying that changeset to 
+** database zFrom the contents of the two compatible tables would be 
+** identical.
+**
+** It an error if database zFrom does not exist or does not contain the
+** required compatible table.
+**
+** If the operation successful, SQLITE_OK is returned. Otherwise, an SQLite
+** error code. In this case, if argument pzErrMsg is not NULL, *pzErrMsg
+** may be set to point to a buffer containing an English language error 
+** message. It is the responsibility of the caller to free this buffer using
+** sqlite3_free().
+*/
+int sqlite3session_diff(
+  sqlite3_session *pSession,
+  const char *zFromDb,
+  const char *zTbl,
+  char **pzErrMsg
+);
+
+
+/*
+** CAPI3REF: Generate A Patchset From A Session Object
+**
+** The differences between a patchset and a changeset are that:
+**
+** <ul>
+**   <li> DELETE records consist of the primary key fields only. The 
+**        original values of other fields are omitted.
+**   <li> The original values of any modified fields are omitted from 
+**        UPDATE records.
+** </ul>
+**
+** A patchset blob may be used with up to date versions of all 
+** sqlite3changeset_xxx API functions except for sqlite3changeset_invert(), 
+** which returns SQLITE_CORRUPT if it is passed a patchset. Similarly,
+** attempting to use a patchset blob with old versions of the
+** sqlite3changeset_xxx APIs also provokes an SQLITE_CORRUPT error. 
+**
+** Because the non-primary key "old.*" fields are omitted, no 
+** SQLITE_CHANGESET_DATA conflicts can be detected or reported if a patchset
+** is passed to the sqlite3changeset_apply() API. Other conflict types work
+** in the same way as for changesets.
+**
+** Changes within a patchset are ordered in the same way as for changesets
+** generated by the sqlite3session_changeset() function (i.e. all changes for
+** a single table are grouped together, tables appear in the order in which
+** they were attached to the session object).
+*/
+int sqlite3session_patchset(
+  sqlite3_session *pSession,      /* Session object */
+  int *pnPatchset,                /* OUT: Size of buffer at *ppChangeset */
+  void **ppPatchset               /* OUT: Buffer containing changeset */
+);
+
+/*
+** CAPI3REF: Test if a changeset has recorded any changes.
+**
+** Return non-zero if no changes to attached tables have been recorded by 
+** the session object passed as the first argument. Otherwise, if one or 
+** more changes have been recorded, return zero.
+**
+** Even if this function returns zero, it is possible that calling
+** [sqlite3session_changeset()] on the session handle may still return a
+** changeset that contains no changes. This can happen when a row in 
+** an attached table is modified and then later on the original values 
+** are restored. However, if this function returns non-zero, then it is
+** guaranteed that a call to sqlite3session_changeset() will return a 
+** changeset containing zero changes.
+*/
+int sqlite3session_isempty(sqlite3_session *pSession);
+
+/*
+** CAPI3REF: Create An Iterator To Traverse A Changeset 
+**
+** Create an iterator used to iterate through the contents of a changeset.
+** If successful, *pp is set to point to the iterator handle and SQLITE_OK
+** is returned. Otherwise, if an error occurs, *pp is set to zero and an
+** SQLite error code is returned.
+**
+** The following functions can be used to advance and query a changeset 
+** iterator created by this function:
+**
+** <ul>
+**   <li> [sqlite3changeset_next()]
+**   <li> [sqlite3changeset_op()]
+**   <li> [sqlite3changeset_new()]
+**   <li> [sqlite3changeset_old()]
+** </ul>
+**
+** It is the responsibility of the caller to eventually destroy the iterator
+** by passing it to [sqlite3changeset_finalize()]. The buffer containing the
+** changeset (pChangeset) must remain valid until after the iterator is
+** destroyed.
+**
+** Assuming the changeset blob was created by one of the
+** [sqlite3session_changeset()], [sqlite3changeset_concat()] or
+** [sqlite3changeset_invert()] functions, all changes within the changeset 
+** that apply to a single table are grouped together. This means that when 
+** an application iterates through a changeset using an iterator created by 
+** this function, all changes that relate to a single table are visited 
+** consecutively. There is no chance that the iterator will visit a change 
+** the applies to table X, then one for table Y, and then later on visit 
+** another change for table X.
+*/
+int sqlite3changeset_start(
+  sqlite3_changeset_iter **pp,    /* OUT: New changeset iterator handle */
+  int nChangeset,                 /* Size of changeset blob in bytes */
+  void *pChangeset                /* Pointer to blob containing changeset */
+);
+
+
+/*
+** CAPI3REF: Advance A Changeset Iterator
+**
+** This function may only be used with iterators created by function
+** [sqlite3changeset_start()]. If it is called on an iterator passed to
+** a conflict-handler callback by [sqlite3changeset_apply()], SQLITE_MISUSE
+** is returned and the call has no effect.
+**
+** Immediately after an iterator is created by sqlite3changeset_start(), it
+** does not point to any change in the changeset. Assuming the changeset
+** is not empty, the first call to this function advances the iterator to
+** point to the first change in the changeset. Each subsequent call advances
+** the iterator to point to the next change in the changeset (if any). If
+** no error occurs and the iterator points to a valid change after a call
+** to sqlite3changeset_next() has advanced it, SQLITE_ROW is returned. 
+** Otherwise, if all changes in the changeset have already been visited,
+** SQLITE_DONE is returned.
+**
+** If an error occurs, an SQLite error code is returned. Possible error 
+** codes include SQLITE_CORRUPT (if the changeset buffer is corrupt) or 
+** SQLITE_NOMEM.
+*/
+int sqlite3changeset_next(sqlite3_changeset_iter *pIter);
+
+/*
+** CAPI3REF: Obtain The Current Operation From A Changeset Iterator
+**
+** The pIter argument passed to this function may either be an iterator
+** passed to a conflict-handler by [sqlite3changeset_apply()], or an iterator
+** created by [sqlite3changeset_start()]. In the latter case, the most recent
+** call to [sqlite3changeset_next()] must have returned [SQLITE_ROW]. If this
+** is not the case, this function returns [SQLITE_MISUSE].
+**
+** If argument pzTab is not NULL, then *pzTab is set to point to a
+** nul-terminated utf-8 encoded string containing the name of the table
+** affected by the current change. The buffer remains valid until either
+** sqlite3changeset_next() is called on the iterator or until the 
+** conflict-handler function returns. If pnCol is not NULL, then *pnCol is 
+** set to the number of columns in the table affected by the change. If
+** pbIncorrect is not NULL, then *pbIndirect is set to true (1) if the change
+** is an indirect change, or false (0) otherwise. See the documentation for
+** [sqlite3session_indirect()] for a description of direct and indirect
+** changes. Finally, if pOp is not NULL, then *pOp is set to one of 
+** [SQLITE_INSERT], [SQLITE_DELETE] or [SQLITE_UPDATE], depending on the 
+** type of change that the iterator currently points to.
+**
+** If no error occurs, SQLITE_OK is returned. If an error does occur, an
+** SQLite error code is returned. The values of the output variables may not
+** be trusted in this case.
+*/
+int sqlite3changeset_op(
+  sqlite3_changeset_iter *pIter,  /* Iterator object */
+  const char **pzTab,             /* OUT: Pointer to table name */
+  int *pnCol,                     /* OUT: Number of columns in table */
+  int *pOp,                       /* OUT: SQLITE_INSERT, DELETE or UPDATE */
+  int *pbIndirect                 /* OUT: True for an 'indirect' change */
+);
+
+/*
+** CAPI3REF: Obtain The Primary Key Definition Of A Table
+**
+** For each modified table, a changeset includes the following:
+**
+** <ul>
+**   <li> The number of columns in the table, and
+**   <li> Which of those columns make up the tables PRIMARY KEY.
+** </ul>
+**
+** This function is used to find which columns comprise the PRIMARY KEY of
+** the table modified by the change that iterator pIter currently points to.
+** If successful, *pabPK is set to point to an array of nCol entries, where
+** nCol is the number of columns in the table. Elements of *pabPK are set to
+** 0x01 if the corresponding column is part of the tables primary key, or
+** 0x00 if it is not.
+**
+** If argument pnCol is not NULL, then *pnCol is set to the number of columns
+** in the table.
+**
+** If this function is called when the iterator does not point to a valid
+** entry, SQLITE_MISUSE is returned and the output variables zeroed. Otherwise,
+** SQLITE_OK is returned and the output variables populated as described
+** above.
+*/
+int sqlite3changeset_pk(
+  sqlite3_changeset_iter *pIter,  /* Iterator object */
+  unsigned char **pabPK,          /* OUT: Array of boolean - true for PK cols */
+  int *pnCol                      /* OUT: Number of entries in output array */
+);
+
+/*
+** CAPI3REF: Obtain old.* Values From A Changeset Iterator
+**
+** The pIter argument passed to this function may either be an iterator
+** passed to a conflict-handler by [sqlite3changeset_apply()], or an iterator
+** created by [sqlite3changeset_start()]. In the latter case, the most recent
+** call to [sqlite3changeset_next()] must have returned SQLITE_ROW. 
+** Furthermore, it may only be called if the type of change that the iterator
+** currently points to is either [SQLITE_DELETE] or [SQLITE_UPDATE]. Otherwise,
+** this function returns [SQLITE_MISUSE] and sets *ppValue to NULL.
+**
+** Argument iVal must be greater than or equal to 0, and less than the number
+** of columns in the table affected by the current change. Otherwise,
+** [SQLITE_RANGE] is returned and *ppValue is set to NULL.
+**
+** If successful, this function sets *ppValue to point to a protected
+** sqlite3_value object containing the iVal'th value from the vector of 
+** original row values stored as part of the UPDATE or DELETE change and
+** returns SQLITE_OK. The name of the function comes from the fact that this 
+** is similar to the "old.*" columns available to update or delete triggers.
+**
+** If some other error occurs (e.g. an OOM condition), an SQLite error code
+** is returned and *ppValue is set to NULL.
+*/
+int sqlite3changeset_old(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int iVal,                       /* Column number */
+  sqlite3_value **ppValue         /* OUT: Old value (or NULL pointer) */
+);
+
+/*
+** CAPI3REF: Obtain new.* Values From A Changeset Iterator
+**
+** The pIter argument passed to this function may either be an iterator
+** passed to a conflict-handler by [sqlite3changeset_apply()], or an iterator
+** created by [sqlite3changeset_start()]. In the latter case, the most recent
+** call to [sqlite3changeset_next()] must have returned SQLITE_ROW. 
+** Furthermore, it may only be called if the type of change that the iterator
+** currently points to is either [SQLITE_UPDATE] or [SQLITE_INSERT]. Otherwise,
+** this function returns [SQLITE_MISUSE] and sets *ppValue to NULL.
+**
+** Argument iVal must be greater than or equal to 0, and less than the number
+** of columns in the table affected by the current change. Otherwise,
+** [SQLITE_RANGE] is returned and *ppValue is set to NULL.
+**
+** If successful, this function sets *ppValue to point to a protected
+** sqlite3_value object containing the iVal'th value from the vector of 
+** new row values stored as part of the UPDATE or INSERT change and
+** returns SQLITE_OK. If the change is an UPDATE and does not include
+** a new value for the requested column, *ppValue is set to NULL and 
+** SQLITE_OK returned. The name of the function comes from the fact that 
+** this is similar to the "new.*" columns available to update or delete 
+** triggers.
+**
+** If some other error occurs (e.g. an OOM condition), an SQLite error code
+** is returned and *ppValue is set to NULL.
+*/
+int sqlite3changeset_new(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int iVal,                       /* Column number */
+  sqlite3_value **ppValue         /* OUT: New value (or NULL pointer) */
+);
+
+/*
+** CAPI3REF: Obtain Conflicting Row Values From A Changeset Iterator
+**
+** This function should only be used with iterator objects passed to a
+** conflict-handler callback by [sqlite3changeset_apply()] with either
+** [SQLITE_CHANGESET_DATA] or [SQLITE_CHANGESET_CONFLICT]. If this function
+** is called on any other iterator, [SQLITE_MISUSE] is returned and *ppValue
+** is set to NULL.
+**
+** Argument iVal must be greater than or equal to 0, and less than the number
+** of columns in the table affected by the current change. Otherwise,
+** [SQLITE_RANGE] is returned and *ppValue is set to NULL.
+**
+** If successful, this function sets *ppValue to point to a protected
+** sqlite3_value object containing the iVal'th value from the 
+** "conflicting row" associated with the current conflict-handler callback
+** and returns SQLITE_OK.
+**
+** If some other error occurs (e.g. an OOM condition), an SQLite error code
+** is returned and *ppValue is set to NULL.
+*/
+int sqlite3changeset_conflict(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int iVal,                       /* Column number */
+  sqlite3_value **ppValue         /* OUT: Value from conflicting row */
+);
+
+/*
+** CAPI3REF: Determine The Number Of Foreign Key Constraint Violations
+**
+** This function may only be called with an iterator passed to an
+** SQLITE_CHANGESET_FOREIGN_KEY conflict handler callback. In this case
+** it sets the output variable to the total number of known foreign key
+** violations in the destination database and returns SQLITE_OK.
+**
+** In all other cases this function returns SQLITE_MISUSE.
+*/
+int sqlite3changeset_fk_conflicts(
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  int *pnOut                      /* OUT: Number of FK violations */
+);
+
+
+/*
+** CAPI3REF: Finalize A Changeset Iterator
+**
+** This function is used to finalize an iterator allocated with
+** [sqlite3changeset_start()].
+**
+** This function should only be called on iterators created using the
+** [sqlite3changeset_start()] function. If an application calls this
+** function with an iterator passed to a conflict-handler by
+** [sqlite3changeset_apply()], [SQLITE_MISUSE] is immediately returned and the
+** call has no effect.
+**
+** If an error was encountered within a call to an sqlite3changeset_xxx()
+** function (for example an [SQLITE_CORRUPT] in [sqlite3changeset_next()] or an 
+** [SQLITE_NOMEM] in [sqlite3changeset_new()]) then an error code corresponding
+** to that error is returned by this function. Otherwise, SQLITE_OK is
+** returned. This is to allow the following pattern (pseudo-code):
+**
+**   sqlite3changeset_start();
+**   while( SQLITE_ROW==sqlite3changeset_next() ){
+**     // Do something with change.
+**   }
+**   rc = sqlite3changeset_finalize();
+**   if( rc!=SQLITE_OK ){
+**     // An error has occurred 
+**   }
+*/
+int sqlite3changeset_finalize(sqlite3_changeset_iter *pIter);
+
+/*
+** CAPI3REF: Invert A Changeset
+**
+** This function is used to "invert" a changeset object. Applying an inverted
+** changeset to a database reverses the effects of applying the uninverted
+** changeset. Specifically:
+**
+** <ul>
+**   <li> Each DELETE change is changed to an INSERT, and
+**   <li> Each INSERT change is changed to a DELETE, and
+**   <li> For each UPDATE change, the old.* and new.* values are exchanged.
+** </ul>
+**
+** This function does not change the order in which changes appear within
+** the changeset. It merely reverses the sense of each individual change.
+**
+** If successful, a pointer to a buffer containing the inverted changeset
+** is stored in *ppOut, the size of the same buffer is stored in *pnOut, and
+** SQLITE_OK is returned. If an error occurs, both *pnOut and *ppOut are
+** zeroed and an SQLite error code returned.
+**
+** It is the responsibility of the caller to eventually call sqlite3_free()
+** on the *ppOut pointer to free the buffer allocation following a successful 
+** call to this function.
+**
+** WARNING/TODO: This function currently assumes that the input is a valid
+** changeset. If it is not, the results are undefined.
+*/
+int sqlite3changeset_invert(
+  int nIn, const void *pIn,       /* Input changeset */
+  int *pnOut, void **ppOut        /* OUT: Inverse of input */
+);
+
+/*
+** CAPI3REF: Concatenate Two Changeset Objects
+**
+** This function is used to concatenate two changesets, A and B, into a 
+** single changeset. The result is a changeset equivalent to applying
+** changeset A followed by changeset B. 
+**
+** This function combines the two input changesets using an 
+** sqlite3_changegroup object. Calling it produces similar results as the
+** following code fragment:
+**
+**   sqlite3_changegroup *pGrp;
+**   rc = sqlite3_changegroup_new(&pGrp);
+**   if( rc==SQLITE_OK ) rc = sqlite3changegroup_add(pGrp, nA, pA);
+**   if( rc==SQLITE_OK ) rc = sqlite3changegroup_add(pGrp, nB, pB);
+**   if( rc==SQLITE_OK ){
+**     rc = sqlite3changegroup_output(pGrp, pnOut, ppOut);
+**   }else{
+**     *ppOut = 0;
+**     *pnOut = 0;
+**   }
+**
+** Refer to the sqlite3_changegroup documentation below for details.
+*/
+int sqlite3changeset_concat(
+  int nA,                         /* Number of bytes in buffer pA */
+  void *pA,                       /* Pointer to buffer containing changeset A */
+  int nB,                         /* Number of bytes in buffer pB */
+  void *pB,                       /* Pointer to buffer containing changeset B */
+  int *pnOut,                     /* OUT: Number of bytes in output changeset */
+  void **ppOut                    /* OUT: Buffer containing output changeset */
+);
+
+
+/*
+** CAPI3REF: Changegroup Handle
+*/
+typedef struct sqlite3_changegroup sqlite3_changegroup;
+
+/*
+** CAPI3REF: Create A New Changegroup Object
+**
+** An sqlite3_changegroup object is used to combine two or more changesets
+** (or patchsets) into a single changeset (or patchset). A single changegroup
+** object may combine changesets or patchsets, but not both. The output is
+** always in the same format as the input.
+**
+** If successful, this function returns SQLITE_OK and populates (*pp) with
+** a pointer to a new sqlite3_changegroup object before returning. The caller
+** should eventually free the returned object using a call to 
+** sqlite3changegroup_delete(). If an error occurs, an SQLite error code
+** (i.e. SQLITE_NOMEM) is returned and *pp is set to NULL.
+**
+** The usual usage pattern for an sqlite3_changegroup object is as follows:
+**
+** <ul>
+**   <li> It is created using a call to sqlite3changegroup_new().
+**
+**   <li> Zero or more changesets (or patchsets) are added to the object
+**        by calling sqlite3changegroup_add().
+**
+**   <li> The result of combining all input changesets together is obtained 
+**        by the application via a call to sqlite3changegroup_output().
+**
+**   <li> The object is deleted using a call to sqlite3changegroup_delete().
+** </ul>
+**
+** Any number of calls to add() and output() may be made between the calls to
+** new() and delete(), and in any order.
+**
+** As well as the regular sqlite3changegroup_add() and 
+** sqlite3changegroup_output() functions, also available are the streaming
+** versions sqlite3changegroup_add_strm() and sqlite3changegroup_output_strm().
+*/
+int sqlite3changegroup_new(sqlite3_changegroup **pp);
+
+/*
+** CAPI3REF: Add A Changeset To A Changegroup
+**
+** Add all changes within the changeset (or patchset) in buffer pData (size
+** nData bytes) to the changegroup. 
+**
+** If the buffer contains a patchset, then all prior calls to this function
+** on the same changegroup object must also have specified patchsets. Or, if
+** the buffer contains a changeset, so must have the earlier calls to this
+** function. Otherwise, SQLITE_ERROR is returned and no changes are added
+** to the changegroup.
+**
+** Rows within the changeset and changegroup are identified by the values in
+** their PRIMARY KEY columns. A change in the changeset is considered to
+** apply to the same row as a change already present in the changegroup if
+** the two rows have the same primary key.
+**
+** Changes to rows that do not already appear in the changegroup are
+** simply copied into it. Or, if both the new changeset and the changegroup
+** contain changes that apply to a single row, the final contents of the
+** changegroup depends on the type of each change, as follows:
+**
+** <table border=1 style="margin-left:8ex;margin-right:8ex">
+**   <tr><th style="white-space:pre">Existing Change  </th>
+**       <th style="white-space:pre">New Change       </th>
+**       <th>Output Change
+**   <tr><td>INSERT <td>INSERT <td>
+**       The new change is ignored. This case does not occur if the new
+**       changeset was recorded immediately after the changesets already
+**       added to the changegroup.
+**   <tr><td>INSERT <td>UPDATE <td>
+**       The INSERT change remains in the changegroup. The values in the 
+**       INSERT change are modified as if the row was inserted by the
+**       existing change and then updated according to the new change.
+**   <tr><td>INSERT <td>DELETE <td>
+**       The existing INSERT is removed from the changegroup. The DELETE is
+**       not added.
+**   <tr><td>UPDATE <td>INSERT <td>
+**       The new change is ignored. This case does not occur if the new
+**       changeset was recorded immediately after the changesets already
+**       added to the changegroup.
+**   <tr><td>UPDATE <td>UPDATE <td>
+**       The existing UPDATE remains within the changegroup. It is amended 
+**       so that the accompanying values are as if the row was updated once 
+**       by the existing change and then again by the new change.
+**   <tr><td>UPDATE <td>DELETE <td>
+**       The existing UPDATE is replaced by the new DELETE within the
+**       changegroup.
+**   <tr><td>DELETE <td>INSERT <td>
+**       If one or more of the column values in the row inserted by the
+**       new change differ from those in the row deleted by the existing 
+**       change, the existing DELETE is replaced by an UPDATE within the
+**       changegroup. Otherwise, if the inserted row is exactly the same 
+**       as the deleted row, the existing DELETE is simply discarded.
+**   <tr><td>DELETE <td>UPDATE <td>
+**       The new change is ignored. This case does not occur if the new
+**       changeset was recorded immediately after the changesets already
+**       added to the changegroup.
+**   <tr><td>DELETE <td>DELETE <td>
+**       The new change is ignored. This case does not occur if the new
+**       changeset was recorded immediately after the changesets already
+**       added to the changegroup.
+** </table>
+**
+** If the new changeset contains changes to a table that is already present
+** in the changegroup, then the number of columns and the position of the
+** primary key columns for the table must be consistent. If this is not the
+** case, this function fails with SQLITE_SCHEMA. If the input changeset
+** appears to be corrupt and the corruption is detected, SQLITE_CORRUPT is
+** returned. Or, if an out-of-memory condition occurs during processing, this
+** function returns SQLITE_NOMEM. In all cases, if an error occurs the
+** final contents of the changegroup is undefined.
+**
+** If no error occurs, SQLITE_OK is returned.
+*/
+int sqlite3changegroup_add(sqlite3_changegroup*, int nData, void *pData);
+
+/*
+** CAPI3REF: Obtain A Composite Changeset From A Changegroup
+**
+** Obtain a buffer containing a changeset (or patchset) representing the
+** current contents of the changegroup. If the inputs to the changegroup
+** were themselves changesets, the output is a changeset. Or, if the
+** inputs were patchsets, the output is also a patchset.
+**
+** As with the output of the sqlite3session_changeset() and
+** sqlite3session_patchset() functions, all changes related to a single
+** table are grouped together in the output of this function. Tables appear
+** in the same order as for the very first changeset added to the changegroup.
+** If the second or subsequent changesets added to the changegroup contain
+** changes for tables that do not appear in the first changeset, they are
+** appended onto the end of the output changeset, again in the order in
+** which they are first encountered.
+**
+** If an error occurs, an SQLite error code is returned and the output
+** variables (*pnData) and (*ppData) are set to 0. Otherwise, SQLITE_OK
+** is returned and the output variables are set to the size of and a 
+** pointer to the output buffer, respectively. In this case it is the
+** responsibility of the caller to eventually free the buffer using a
+** call to sqlite3_free().
+*/
+int sqlite3changegroup_output(
+  sqlite3_changegroup*,
+  int *pnData,                    /* OUT: Size of output buffer in bytes */
+  void **ppData                   /* OUT: Pointer to output buffer */
+);
+
+/*
+** CAPI3REF: Delete A Changegroup Object
+*/
+void sqlite3changegroup_delete(sqlite3_changegroup*);
+
+/*
+** CAPI3REF: Apply A Changeset To A Database
+**
+** Apply a changeset to a database. This function attempts to update the
+** "main" database attached to handle db with the changes found in the
+** changeset passed via the second and third arguments.
+**
+** The fourth argument (xFilter) passed to this function is the "filter
+** callback". If it is not NULL, then for each table affected by at least one
+** change in the changeset, the filter callback is invoked with
+** the table name as the second argument, and a copy of the context pointer
+** passed as the sixth argument to this function as the first. If the "filter
+** callback" returns zero, then no attempt is made to apply any changes to 
+** the table. Otherwise, if the return value is non-zero or the xFilter
+** argument to this function is NULL, all changes related to the table are
+** attempted.
+**
+** For each table that is not excluded by the filter callback, this function 
+** tests that the target database contains a compatible table. A table is 
+** considered compatible if all of the following are true:
+**
+** <ul>
+**   <li> The table has the same name as the name recorded in the 
+**        changeset, and
+**   <li> The table has the same number of columns as recorded in the 
+**        changeset, and
+**   <li> The table has primary key columns in the same position as 
+**        recorded in the changeset.
+** </ul>
+**
+** If there is no compatible table, it is not an error, but none of the
+** changes associated with the table are applied. A warning message is issued
+** via the sqlite3_log() mechanism with the error code SQLITE_SCHEMA. At most
+** one such warning is issued for each table in the changeset.
+**
+** For each change for which there is a compatible table, an attempt is made 
+** to modify the table contents according to the UPDATE, INSERT or DELETE 
+** change. If a change cannot be applied cleanly, the conflict handler 
+** function passed as the fifth argument to sqlite3changeset_apply() may be 
+** invoked. A description of exactly when the conflict handler is invoked for 
+** each type of change is below.
+**
+** Unlike the xFilter argument, xConflict may not be passed NULL. The results
+** of passing anything other than a valid function pointer as the xConflict
+** argument are undefined.
+**
+** Each time the conflict handler function is invoked, it must return one
+** of [SQLITE_CHANGESET_OMIT], [SQLITE_CHANGESET_ABORT] or 
+** [SQLITE_CHANGESET_REPLACE]. SQLITE_CHANGESET_REPLACE may only be returned
+** if the second argument passed to the conflict handler is either
+** SQLITE_CHANGESET_DATA or SQLITE_CHANGESET_CONFLICT. If the conflict-handler
+** returns an illegal value, any changes already made are rolled back and
+** the call to sqlite3changeset_apply() returns SQLITE_MISUSE. Different 
+** actions are taken by sqlite3changeset_apply() depending on the value
+** returned by each invocation of the conflict-handler function. Refer to
+** the documentation for the three 
+** [SQLITE_CHANGESET_OMIT|available return values] for details.
+**
+** <dl>
+** <dt>DELETE Changes<dd>
+**   For each DELETE change, this function checks if the target database 
+**   contains a row with the same primary key value (or values) as the 
+**   original row values stored in the changeset. If it does, and the values 
+**   stored in all non-primary key columns also match the values stored in 
+**   the changeset the row is deleted from the target database.
+**
+**   If a row with matching primary key values is found, but one or more of
+**   the non-primary key fields contains a value different from the original
+**   row value stored in the changeset, the conflict-handler function is
+**   invoked with [SQLITE_CHANGESET_DATA] as the second argument.
+**
+**   If no row with matching primary key values is found in the database,
+**   the conflict-handler function is invoked with [SQLITE_CHANGESET_NOTFOUND]
+**   passed as the second argument.
+**
+**   If the DELETE operation is attempted, but SQLite returns SQLITE_CONSTRAINT
+**   (which can only happen if a foreign key constraint is violated), the
+**   conflict-handler function is invoked with [SQLITE_CHANGESET_CONSTRAINT]
+**   passed as the second argument. This includes the case where the DELETE
+**   operation is attempted because an earlier call to the conflict handler
+**   function returned [SQLITE_CHANGESET_REPLACE].
+**
+** <dt>INSERT Changes<dd>
+**   For each INSERT change, an attempt is made to insert the new row into
+**   the database.
+**
+**   If the attempt to insert the row fails because the database already 
+**   contains a row with the same primary key values, the conflict handler
+**   function is invoked with the second argument set to 
+**   [SQLITE_CHANGESET_CONFLICT].
+**
+**   If the attempt to insert the row fails because of some other constraint
+**   violation (e.g. NOT NULL or UNIQUE), the conflict handler function is 
+**   invoked with the second argument set to [SQLITE_CHANGESET_CONSTRAINT].
+**   This includes the case where the INSERT operation is re-attempted because 
+**   an earlier call to the conflict handler function returned 
+**   [SQLITE_CHANGESET_REPLACE].
+**
+** <dt>UPDATE Changes<dd>
+**   For each UPDATE change, this function checks if the target database 
+**   contains a row with the same primary key value (or values) as the 
+**   original row values stored in the changeset. If it does, and the values 
+**   stored in all non-primary key columns also match the values stored in 
+**   the changeset the row is updated within the target database.
+**
+**   If a row with matching primary key values is found, but one or more of
+**   the non-primary key fields contains a value different from an original
+**   row value stored in the changeset, the conflict-handler function is
+**   invoked with [SQLITE_CHANGESET_DATA] as the second argument. Since
+**   UPDATE changes only contain values for non-primary key fields that are
+**   to be modified, only those fields need to match the original values to
+**   avoid the SQLITE_CHANGESET_DATA conflict-handler callback.
+**
+**   If no row with matching primary key values is found in the database,
+**   the conflict-handler function is invoked with [SQLITE_CHANGESET_NOTFOUND]
+**   passed as the second argument.
+**
+**   If the UPDATE operation is attempted, but SQLite returns 
+**   SQLITE_CONSTRAINT, the conflict-handler function is invoked with 
+**   [SQLITE_CHANGESET_CONSTRAINT] passed as the second argument.
+**   This includes the case where the UPDATE operation is attempted after 
+**   an earlier call to the conflict handler function returned
+**   [SQLITE_CHANGESET_REPLACE].  
+** </dl>
+**
+** It is safe to execute SQL statements, including those that write to the
+** table that the callback related to, from within the xConflict callback.
+** This can be used to further customize the applications conflict
+** resolution strategy.
+**
+** All changes made by this function are enclosed in a savepoint transaction.
+** If any other error (aside from a constraint failure when attempting to
+** write to the target database) occurs, then the savepoint transaction is
+** rolled back, restoring the target database to its original state, and an 
+** SQLite error code returned.
+*/
+int sqlite3changeset_apply(
+  sqlite3 *db,                    /* Apply change to "main" db of this handle */
+  int nChangeset,                 /* Size of changeset in bytes */
+  void *pChangeset,               /* Changeset blob */
+  int(*xFilter)(
+    void *pCtx,                   /* Copy of sixth arg to _apply() */
+    const char *zTab              /* Table name */
+  ),
+  int(*xConflict)(
+    void *pCtx,                   /* Copy of sixth arg to _apply() */
+    int eConflict,                /* DATA, MISSING, CONFLICT, CONSTRAINT */
+    sqlite3_changeset_iter *p     /* Handle describing change and conflict */
+  ),
+  void *pCtx                      /* First argument passed to xConflict */
+);
+
+/* 
+** CAPI3REF: Constants Passed To The Conflict Handler
+**
+** Values that may be passed as the second argument to a conflict-handler.
+**
+** <dl>
+** <dt>SQLITE_CHANGESET_DATA<dd>
+**   The conflict handler is invoked with CHANGESET_DATA as the second argument
+**   when processing a DELETE or UPDATE change if a row with the required
+**   PRIMARY KEY fields is present in the database, but one or more other 
+**   (non primary-key) fields modified by the update do not contain the 
+**   expected "before" values.
+** 
+**   The conflicting row, in this case, is the database row with the matching
+**   primary key.
+** 
+** <dt>SQLITE_CHANGESET_NOTFOUND<dd>
+**   The conflict handler is invoked with CHANGESET_NOTFOUND as the second
+**   argument when processing a DELETE or UPDATE change if a row with the
+**   required PRIMARY KEY fields is not present in the database.
+** 
+**   There is no conflicting row in this case. The results of invoking the
+**   sqlite3changeset_conflict() API are undefined.
+** 
+** <dt>SQLITE_CHANGESET_CONFLICT<dd>
+**   CHANGESET_CONFLICT is passed as the second argument to the conflict
+**   handler while processing an INSERT change if the operation would result 
+**   in duplicate primary key values.
+** 
+**   The conflicting row in this case is the database row with the matching
+**   primary key.
+**
+** <dt>SQLITE_CHANGESET_FOREIGN_KEY<dd>
+**   If foreign key handling is enabled, and applying a changeset leaves the
+**   database in a state containing foreign key violations, the conflict 
+**   handler is invoked with CHANGESET_FOREIGN_KEY as the second argument
+**   exactly once before the changeset is committed. If the conflict handler
+**   returns CHANGESET_OMIT, the changes, including those that caused the
+**   foreign key constraint violation, are committed. Or, if it returns
+**   CHANGESET_ABORT, the changeset is rolled back.
+**
+**   No current or conflicting row information is provided. The only function
+**   it is possible to call on the supplied sqlite3_changeset_iter handle
+**   is sqlite3changeset_fk_conflicts().
+** 
+** <dt>SQLITE_CHANGESET_CONSTRAINT<dd>
+**   If any other constraint violation occurs while applying a change (i.e. 
+**   a UNIQUE, CHECK or NOT NULL constraint), the conflict handler is 
+**   invoked with CHANGESET_CONSTRAINT as the second argument.
+** 
+**   There is no conflicting row in this case. The results of invoking the
+**   sqlite3changeset_conflict() API are undefined.
+**
+** </dl>
+*/
+#define SQLITE_CHANGESET_DATA        1
+#define SQLITE_CHANGESET_NOTFOUND    2
+#define SQLITE_CHANGESET_CONFLICT    3
+#define SQLITE_CHANGESET_CONSTRAINT  4
+#define SQLITE_CHANGESET_FOREIGN_KEY 5
+
+/* 
+** CAPI3REF: Constants Returned By The Conflict Handler
+**
+** A conflict handler callback must return one of the following three values.
+**
+** <dl>
+** <dt>SQLITE_CHANGESET_OMIT<dd>
+**   If a conflict handler returns this value no special action is taken. The
+**   change that caused the conflict is not applied. The session module 
+**   continues to the next change in the changeset.
+**
+** <dt>SQLITE_CHANGESET_REPLACE<dd>
+**   This value may only be returned if the second argument to the conflict
+**   handler was SQLITE_CHANGESET_DATA or SQLITE_CHANGESET_CONFLICT. If this
+**   is not the case, any changes applied so far are rolled back and the 
+**   call to sqlite3changeset_apply() returns SQLITE_MISUSE.
+**
+**   If CHANGESET_REPLACE is returned by an SQLITE_CHANGESET_DATA conflict
+**   handler, then the conflicting row is either updated or deleted, depending
+**   on the type of change.
+**
+**   If CHANGESET_REPLACE is returned by an SQLITE_CHANGESET_CONFLICT conflict
+**   handler, then the conflicting row is removed from the database and a
+**   second attempt to apply the change is made. If this second attempt fails,
+**   the original row is restored to the database before continuing.
+**
+** <dt>SQLITE_CHANGESET_ABORT<dd>
+**   If this value is returned, any changes applied so far are rolled back 
+**   and the call to sqlite3changeset_apply() returns SQLITE_ABORT.
+** </dl>
+*/
+#define SQLITE_CHANGESET_OMIT       0
+#define SQLITE_CHANGESET_REPLACE    1
+#define SQLITE_CHANGESET_ABORT      2
+
+/*
+** CAPI3REF: Streaming Versions of API functions.
+**
+** The six streaming API xxx_strm() functions serve similar purposes to the 
+** corresponding non-streaming API functions:
+**
+** <table border=1 style="margin-left:8ex;margin-right:8ex">
+**   <tr><th>Streaming function<th>Non-streaming equivalent</th>
+**   <tr><td>sqlite3changeset_apply_str<td>[sqlite3changeset_apply] 
+**   <tr><td>sqlite3changeset_concat_str<td>[sqlite3changeset_concat] 
+**   <tr><td>sqlite3changeset_invert_str<td>[sqlite3changeset_invert] 
+**   <tr><td>sqlite3changeset_start_str<td>[sqlite3changeset_start] 
+**   <tr><td>sqlite3session_changeset_str<td>[sqlite3session_changeset] 
+**   <tr><td>sqlite3session_patchset_str<td>[sqlite3session_patchset] 
+** </table>
+**
+** Non-streaming functions that accept changesets (or patchsets) as input
+** require that the entire changeset be stored in a single buffer in memory. 
+** Similarly, those that return a changeset or patchset do so by returning 
+** a pointer to a single large buffer allocated using sqlite3_malloc(). 
+** Normally this is convenient. However, if an application running in a 
+** low-memory environment is required to handle very large changesets, the
+** large contiguous memory allocations required can become onerous.
+**
+** In order to avoid this problem, instead of a single large buffer, input
+** is passed to a streaming API functions by way of a callback function that
+** the sessions module invokes to incrementally request input data as it is
+** required. In all cases, a pair of API function parameters such as
+**
+**  <pre>
+**  &nbsp;     int nChangeset,
+**  &nbsp;     void *pChangeset,
+**  </pre>
+**
+** Is replaced by:
+**
+**  <pre>
+**  &nbsp;     int (*xInput)(void *pIn, void *pData, int *pnData),
+**  &nbsp;     void *pIn,
+**  </pre>
+**
+** Each time the xInput callback is invoked by the sessions module, the first
+** argument passed is a copy of the supplied pIn context pointer. The second 
+** argument, pData, points to a buffer (*pnData) bytes in size. Assuming no 
+** error occurs the xInput method should copy up to (*pnData) bytes of data 
+** into the buffer and set (*pnData) to the actual number of bytes copied 
+** before returning SQLITE_OK. If the input is completely exhausted, (*pnData) 
+** should be set to zero to indicate this. Or, if an error occurs, an SQLite 
+** error code should be returned. In all cases, if an xInput callback returns
+** an error, all processing is abandoned and the streaming API function
+** returns a copy of the error code to the caller.
+**
+** In the case of sqlite3changeset_start_strm(), the xInput callback may be
+** invoked by the sessions module at any point during the lifetime of the
+** iterator. If such an xInput callback returns an error, the iterator enters
+** an error state, whereby all subsequent calls to iterator functions 
+** immediately fail with the same error code as returned by xInput.
+**
+** Similarly, streaming API functions that return changesets (or patchsets)
+** return them in chunks by way of a callback function instead of via a
+** pointer to a single large buffer. In this case, a pair of parameters such
+** as:
+**
+**  <pre>
+**  &nbsp;     int *pnChangeset,
+**  &nbsp;     void **ppChangeset,
+**  </pre>
+**
+** Is replaced by:
+**
+**  <pre>
+**  &nbsp;     int (*xOutput)(void *pOut, const void *pData, int nData),
+**  &nbsp;     void *pOut
+**  </pre>
+**
+** The xOutput callback is invoked zero or more times to return data to
+** the application. The first parameter passed to each call is a copy of the
+** pOut pointer supplied by the application. The second parameter, pData,
+** points to a buffer nData bytes in size containing the chunk of output
+** data being returned. If the xOutput callback successfully processes the
+** supplied data, it should return SQLITE_OK to indicate success. Otherwise,
+** it should return some other SQLite error code. In this case processing
+** is immediately abandoned and the streaming API function returns a copy
+** of the xOutput error code to the application.
+**
+** The sessions module never invokes an xOutput callback with the third 
+** parameter set to a value less than or equal to zero. Other than this,
+** no guarantees are made as to the size of the chunks of data returned.
+*/
+int sqlite3changeset_apply_strm(
+  sqlite3 *db,                    /* Apply change to "main" db of this handle */
+  int (*xInput)(void *pIn, void *pData, int *pnData), /* Input function */
+  void *pIn,                                          /* First arg for xInput */
+  int(*xFilter)(
+    void *pCtx,                   /* Copy of sixth arg to _apply() */
+    const char *zTab              /* Table name */
+  ),
+  int(*xConflict)(
+    void *pCtx,                   /* Copy of sixth arg to _apply() */
+    int eConflict,                /* DATA, MISSING, CONFLICT, CONSTRAINT */
+    sqlite3_changeset_iter *p     /* Handle describing change and conflict */
+  ),
+  void *pCtx                      /* First argument passed to xConflict */
+);
+int sqlite3changeset_concat_strm(
+  int (*xInputA)(void *pIn, void *pData, int *pnData),
+  void *pInA,
+  int (*xInputB)(void *pIn, void *pData, int *pnData),
+  void *pInB,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut
+);
+int sqlite3changeset_invert_strm(
+  int (*xInput)(void *pIn, void *pData, int *pnData),
+  void *pIn,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut
+);
+int sqlite3changeset_start_strm(
+  sqlite3_changeset_iter **pp,
+  int (*xInput)(void *pIn, void *pData, int *pnData),
+  void *pIn
+);
+int sqlite3session_changeset_strm(
+  sqlite3_session *pSession,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut
+);
+int sqlite3session_patchset_strm(
+  sqlite3_session *pSession,
+  int (*xOutput)(void *pOut, const void *pData, int nData),
+  void *pOut
+);
+int sqlite3changegroup_add_strm(sqlite3_changegroup*, 
+    int (*xInput)(void *pIn, void *pData, int *pnData),
+    void *pIn
+);
+int sqlite3changegroup_output_strm(sqlite3_changegroup*,
+    int (*xOutput)(void *pOut, const void *pData, int nData), 
+    void *pOut
+);
+
+
+/*
+** Make sure we can call this stuff from C++.
+*/
+#ifdef __cplusplus
+}
+#endif
+
+#endif  /* !defined(__SQLITESESSION_H_) && defined(SQLITE_ENABLE_SESSION) */
diff --git a/libs/tdlib/td/src.ps1 b/libs/tdlib/td/src.ps1
new file mode 100644
index 0000000000..c5d1d1d619
--- /dev/null
+++ b/libs/tdlib/td/src.ps1
@@ -0,0 +1 @@
+git ls-tree -r HEAD --name-only benchmark example memprof td tdactor tddb tdnet tdtl tdutils test tg_http_client | Select-String "\.cpp$|\.h$|\.hpp$" | Select-String -NotMatch "third_party"
diff --git a/libs/tdlib/td/src.sh b/libs/tdlib/td/src.sh
new file mode 100644
index 0000000000..5b89d9d40d
--- /dev/null
+++ b/libs/tdlib/td/src.sh
@@ -0,0 +1,2 @@
+#!/bin/bash
+git ls-tree -r HEAD --name-only benchmark example memprof td tdactor tddb tdnet tdtl tdutils test tg_http_client | grep -E "\.cpp$|\.h$|\.hpp$" | grep -v third_party
diff --git a/libs/tdlib/td/td/generate/CMakeLists.txt b/libs/tdlib/td/td/generate/CMakeLists.txt
new file mode 100644
index 0000000000..0b07d61604
--- /dev/null
+++ b/libs/tdlib/td/td/generate/CMakeLists.txt
@@ -0,0 +1,156 @@
+cmake_minimum_required(VERSION 3.0.2 FATAL_ERROR)
+
+file(MAKE_DIRECTORY auto/td/telegram)
+file(MAKE_DIRECTORY auto/td/mtproto)
+
+set(TL_TD_AUTO_INCLUDES ${CMAKE_CURRENT_SOURCE_DIR}/auto PARENT_SCOPE)
+
+set(TL_TD_AUTO
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/mtproto/mtproto_api.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/mtproto/mtproto_api.h
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/mtproto/mtproto_api.hpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/telegram/td_api.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/telegram/td_api.h
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/telegram/td_api.hpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/telegram/telegram_api.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/telegram/telegram_api.h
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/telegram/telegram_api.hpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/telegram/secret_api.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/telegram/secret_api.h
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/telegram/secret_api.hpp
+  PARENT_SCOPE
+)
+
+set(TL_TD_JSON_AUTO
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/telegram/td_api_json.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/telegram/td_api_json.h
+  PARENT_SCOPE
+)
+
+set(TL_TD_API_TLO ${CMAKE_CURRENT_SOURCE_DIR}/scheme/td_api.tlo)
+set(TL_TD_API_TLO ${TL_TD_API_TLO} PARENT_SCOPE)
+
+set(TL_C_AUTO
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/telegram/td_tdc_api.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/telegram/td_tdc_api.h
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/telegram/td_tdc_api_inner.h
+  PARENT_SCOPE
+)
+
+set(TL_DOTNET_AUTO
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/telegram/TdDotNetApi.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/td/telegram/TdDotNetApi.h
+  PARENT_SCOPE
+)
+
+set(TL_GENERATE_COMMON_SOURCE
+  generate_common.cpp
+
+  tl_writer_cpp.cpp
+  tl_writer_h.cpp
+  tl_writer_hpp.cpp
+  tl_writer_jni_cpp.cpp
+  tl_writer_jni_h.cpp
+  tl_writer_td.cpp
+
+  tl_writer_cpp.h
+  tl_writer_h.h
+  tl_writer_hpp.h
+  tl_writer_jni_cpp.h
+  tl_writer_jni_h.h
+  tl_writer_td.h
+)
+
+set(TL_GENERATE_C_SOURCE
+  generate_c.cpp
+
+  tl_writer_c.h
+)
+
+set(TL_GENERATE_JAVA_SOURCE
+  generate_java.cpp
+
+  tl_writer_java.cpp
+
+  tl_writer_java.h
+)
+
+set(TL_GENERATE_JSON_SOURCE
+  generate_json.cpp
+
+  tl_json_converter.cpp
+
+  tl_json_converter.h
+)
+
+if (NOT CMAKE_CROSSCOMPILING)
+  find_program(PHP_EXECUTABLE php)
+
+  if (PHP_EXECUTABLE AND NOT TD_ENABLE_DOTNET)
+    set(GENERATE_COMMON_CMD generate_common && ${PHP_EXECUTABLE} DoxygenTlDocumentationGenerator.php scheme/td_api.tl auto/td/telegram/td_api.h)
+  else()
+    set(GENERATE_COMMON_CMD generate_common)
+  endif()
+
+  add_executable(generate_common ${TL_GENERATE_COMMON_SOURCE})
+  target_link_libraries(generate_common PRIVATE tdtl)
+  add_custom_target(tl_generate_common
+    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+    COMMAND ${GENERATE_COMMON_CMD}
+    COMMENT "Generate common tl source files"
+    DEPENDS generate_common scheme/mtproto_api.tlo scheme/telegram_api.tlo scheme/secret_api.tlo ${TL_TD_API_TLO} DoxygenTlDocumentationGenerator.php
+  )
+  if (TD_ENABLE_JNI)
+    target_compile_definitions(generate_common PRIVATE TD_ENABLE_JNI=1)
+  endif()
+  if (TD_ENABLE_DOTNET)
+    target_compile_definitions(generate_common PRIVATE DISABLE_HPP_DOCUMENTATION=1)
+  endif()
+
+  add_executable(generate_c ${TL_GENERATE_C_SOURCE})
+  target_link_libraries(generate_c PRIVATE tdtl)
+  add_custom_target(tl_generate_c
+    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+    COMMAND generate_c
+    COMMENT "Generate C tl source files"
+    DEPENDS generate_c ${TL_TD_API_TLO}
+  )
+
+  add_executable(td_generate_java_api ${TL_GENERATE_JAVA_SOURCE})
+  target_link_libraries(td_generate_java_api PRIVATE tdtl)
+
+  add_executable(generate_json ${TL_GENERATE_JSON_SOURCE})
+  target_link_libraries(generate_json PRIVATE tdtl tdutils)
+  add_custom_target(tl_generate_json
+    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+    COMMAND generate_json
+    COMMENT "Generate JSON tl source files"
+    DEPENDS generate_json ${TL_TD_API_TLO}
+  )
+
+  if (TD_ENABLE_JNI)
+    install(TARGETS td_generate_java_api RUNTIME DESTINATION bin)
+    install(FILES JavadocTlDocumentationGenerator.php TlDocumentationGenerator.php DESTINATION bin/td/generate)
+    install(FILES scheme/td_api.tlo scheme/td_api.tl DESTINATION bin/td/generate/scheme)
+  endif()
+
+  if (TD_ENABLE_DOTNET)
+    if (PHP_EXECUTABLE)
+      set(GENERATE_DOTNET_API_CMD td_generate_dotnet_api ${TL_TD_API_TLO} && ${PHP_EXECUTABLE} DotnetTlDocumentationGenerator.php scheme/td_api.tl auto/td/telegram/TdDotNetApi.h)
+    else()
+      set(GENERATE_DOTNET_API_CMD td_generate_dotnet_api ${TL_TD_API_TLO})
+    endif()
+
+    add_executable(td_generate_dotnet_api generate_dotnet.cpp tl_writer_dotnet.h)
+    target_link_libraries(td_generate_dotnet_api PRIVATE tdtl)
+    add_custom_target(generate_dotnet_api
+      WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+      COMMAND ${GENERATE_DOTNET_API_CMD} ${TL_TD_API_TLO}
+      COMMENT "Generate .NET API files"
+      DEPENDS td_generate_dotnet_api ${TL_TD_API_TLO} DotnetTlDocumentationGenerator.php
+    )
+  endif()
+
+  add_executable(remove_documentation remove_documentation.cpp)
+  target_link_libraries(remove_documentation PRIVATE tdtl)
+endif()
diff --git a/libs/tdlib/td/td/generate/DotnetTlDocumentationGenerator.php b/libs/tdlib/td/td/generate/DotnetTlDocumentationGenerator.php
new file mode 100644
index 0000000000..7e11cc6653
--- /dev/null
+++ b/libs/tdlib/td/td/generate/DotnetTlDocumentationGenerator.php
@@ -0,0 +1,223 @@
+<?php
+
+require_once 'TlDocumentationGenerator.php';
+
+class DotnetTlDocumentationGenerator extends TlDocumentationGenerator
+{
+    protected function escapeDocumentation($doc)
+    {
+        $doc = htmlspecialchars($doc, ENT_XML1);
+        $doc = str_replace('*/', '*&#47;', $doc);
+        $doc = preg_replace_callback('/_([A-Za-z])/', function ($matches) {return strtoupper($matches[1]);}, $doc);
+        return $doc;
+    }
+
+    protected function getFieldName($name, $class_name)
+    {
+        $name = ucfirst($this->getParameterName($name, $class_name));
+        if ($name === $class_name) {
+          $name .= 'Value';
+        }
+        return $name;
+    }
+
+    protected function getParameterName($name, $class_name)
+    {
+        if (substr($name, 0, 6) === 'param_') {
+            $name = substr($name, 6);
+        }
+        $name = preg_replace_callback('/_([A-Za-z])/', function ($matches) {return strtoupper($matches[1]);}, trim($name));
+        return $name;
+    }
+
+    protected function getClassName($type)
+    {
+        return implode(array_map('ucfirst', explode('.', trim($type, "\r\n ;"))));
+    }
+
+    protected function getTypeName($type)
+    {
+        switch ($type) {
+            case 'Bool':
+                return 'bool';
+            case 'int32':
+                return 'int32';
+            case 'int53':
+            case 'int64':
+                return 'int64';
+            case 'double':
+                return 'float64';
+            case 'string':
+                return 'String^';
+            case 'bytes':
+                return 'Array<byte>^';
+            case 'bool':
+            case 'int':
+            case 'long':
+            case 'Int':
+            case 'Long':
+            case 'Int32':
+            case 'Int53':
+            case 'Int64':
+            case 'Double':
+            case 'String':
+            case 'Bytes':
+                $this->printError("Wrong type $type");
+                return '';
+            default:
+                if (substr($type, 0, 6) === 'vector') {
+                    if ($type[6] !== '<' || $type[strlen($type) - 1] !== '>') {
+                        $this->printError("Wrong vector subtype in $type");
+                        return '';
+                    }
+                    return 'Array<'.$this->getTypeName(substr($type, 7, -1)).'>^';
+                }
+
+                if (preg_match('/[^A-Za-z0-9.]/', $type)) {
+                    $this->printError("Wrong type $type");
+                    return '';
+                }
+                return $this->getClassName($type).'^';
+        }
+    }
+
+    protected function getBaseClassName($is_function)
+    {
+        return $is_function ? 'Function' : 'Object';
+    }
+
+    protected function needRemoveLine($line)
+    {
+        return strpos(trim($line), '///') === 0;
+    }
+
+    protected function needSkipLine($line)
+    {
+        $line = trim($line);
+        return !$line || $line === 'public:' || $line === 'private:' || $line[0] === '}' ||
+            strpos($line, 'Unmanaged') > 0 || strpos($line, 'PrivateField') > 0 || strpos($line, 'get()') > 0 ||
+            strpos($line, 'void set(') === 0 || preg_match('/^[a-z]* class .*;/', $line) ||
+            strpos($line, 'namespace ') === 0 || strpos($line, '#include ') === 0;
+    }
+
+    protected function isHeaderLine($line)
+    {
+        return false;
+    }
+
+    protected function extractClassName($line)
+    {
+        if (strpos($line, 'public ref class ') !== false || strpos($line, 'public interface class ') !== false) {
+            return explode(' ', $line)[3];
+        }
+        return '';
+    }
+
+    protected function fixLine($line)
+    {
+        return $line;
+    }
+
+    protected function addGlobalDocumentation()
+    {
+        $this->addDocumentation('public interface class Object : BaseObject {', <<<EOT
+/// <summary>
+/// This class is a base class for all TDLib interface classes.
+/// </summary>
+EOT
+);
+
+        $this->addDocumentation('  virtual String^ ToString() override;', <<<EOT
+  /// <summary>
+  /// Returns string representation of the object.
+  /// </summary>
+  /// <returns>Returns string representation of the object.</returns>
+EOT
+);
+
+        $this->addDocumentation('public interface class Function : BaseObject {', <<<EOT
+/// <summary>
+/// This class is a base class for all TDLib interface function-classes.
+/// </summary>
+EOT
+);
+    }
+
+    protected function addAbstractClassDocumentation($class_name, $documentation)
+    {
+        $this->addDocumentation("public interface class $class_name : Object {", <<<EOT
+/// <summary>
+/// This class is an abstract base class.
+/// $documentation
+/// </summary>
+EOT
+);
+    }
+
+    protected function addClassDocumentation($class_name, $base_class_name, $description, $return_type)
+    {
+        $return_type_description = $return_type ? "\r\n/// <para>Returns <see cref=\"".substr($return_type, 0, -1).'"/>.</para>' : '';
+
+        $this->addDocumentation("public ref class $class_name sealed : $base_class_name {", <<<EOT
+/// <summary>
+/// $description$return_type_description
+/// </summary>
+EOT
+);
+    }
+
+    protected function addFieldDocumentation($class_name, $field_name, $type_name, $field_info, $may_be_null)
+    {
+        $end = ';';
+        if (substr($type_name, 0, strlen($field_name)) === $field_name) {
+            $type_name = '::Telegram::Td::Api::'.$type_name;
+            $end = ' {';
+        }
+        $full_line = $class_name."  property $type_name $field_name$end";
+        $this->addDocumentation($full_line, <<<EOT
+  /// <summary>
+  /// $field_info
+  /// </summary>
+EOT
+);
+    }
+
+    protected function addDefaultConstructorDocumentation($class_name)
+    {
+        $this->addDocumentation("  $class_name();", <<<EOT
+  /// <summary>
+  /// Default constructor.
+  /// </summary>
+EOT
+);
+    }
+
+    protected function addFullConstructorDocumentation($class_name, $known_fields, $info)
+    {
+        $full_constructor = "  $class_name(";
+        $colon = '';
+        foreach ($known_fields as $name => $type) {
+            $field_type = $this->getTypeName($type);
+            if (substr($field_type, 0, 5) !== 'Array' && substr($field_type, 0, 6) !== 'String' &&
+                ucfirst($field_type) === $field_type) {
+                $field_type = '::Telegram::Td::Api::'.$field_type;
+            }
+            $full_constructor .= $colon.$field_type.' '.$this->getParameterName($name, $class_name);
+            $colon = ', ';
+        }
+        $full_constructor .= ');';
+
+        $full_doc = <<<EOT
+  /// <summary>
+  /// Constructor for initialization of all fields.
+  /// </summary>
+EOT;
+        foreach ($known_fields as $name => $type) {
+            $full_doc .= '\r\n  /// <param name="'.$this->getParameterName($name, $class_name).'">'.$info[$name]."</param>";
+        }
+        $this->addDocumentation($full_constructor, $full_doc);
+    }
+}
+
+$generator = new DotnetTlDocumentationGenerator();
+$generator->generate($argv[1], $argv[2]);
diff --git a/libs/tdlib/td/td/generate/DoxygenTlDocumentationGenerator.php b/libs/tdlib/td/td/generate/DoxygenTlDocumentationGenerator.php
new file mode 100644
index 0000000000..377e3b3718
--- /dev/null
+++ b/libs/tdlib/td/td/generate/DoxygenTlDocumentationGenerator.php
@@ -0,0 +1,379 @@
+<?php
+
+require_once 'TlDocumentationGenerator.php';
+
+class DoxygenTlDocumentationGenerator extends TlDocumentationGenerator
+{
+    private function getParameterTypeName($type)
+    {
+        switch ($type) {
+            case 'Bool':
+                return 'bool ';
+            case 'int32':
+                return 'std::int32_t ';
+            case 'int53':
+            case 'int64':
+                return 'std::int64_t ';
+            case 'double':
+                return 'double ';
+            case 'string':
+            case 'bytes':
+                return 'std::string const &';
+
+            default:
+                if (substr($type, 0, 6) === 'vector') {
+                    if ($type[6] !== '<' || $type[strlen($type) - 1] !== '>') {
+                        return '';
+                    }
+                    return 'std::vector<'.$this->getTypeName(substr($type, 7, -1)).'> &&';
+                }
+
+                if (preg_match('/[^A-Za-z0-9.]/', $type)) {
+                    return '';
+                }
+                return 'object_ptr<'.$this->getClassName($type).'> &&';
+        }
+    }
+
+    protected function escapeDocumentation($doc)
+    {
+        $doc = htmlspecialchars($doc);
+        $doc = str_replace('*/', '*&#47;', $doc);
+        $doc = str_replace('#', '\#', $doc);
+        return $doc;
+    }
+
+    protected function getFieldName($name, $class_name)
+    {
+        if (substr($name, 0, 6) === 'param_') {
+            $name = substr($name, 6);
+        }
+        return $name.'_';
+    }
+
+    protected function getClassName($type)
+    {
+        return implode(explode('.', trim($type, "\r\n ;")));
+    }
+
+    protected function getTypeName($type)
+    {
+        switch ($type) {
+            case 'Bool':
+                return 'bool';
+            case 'int32':
+                return 'std::int32_t';
+            case 'int53':
+            case 'int64':
+                return 'std::int64_t';
+            case 'double':
+                return 'double';
+            case 'string':
+            case 'bytes':
+                return 'std::string';
+            case 'bool':
+            case 'int':
+            case 'long':
+            case 'Int':
+            case 'Long':
+            case 'Int32':
+            case 'Int53':
+            case 'Int64':
+            case 'Double':
+            case 'String':
+            case 'Bytes':
+                $this->printError("Wrong type $type");
+                return '';
+            default:
+                if (substr($type, 0, 6) === 'vector') {
+                    if ($type[6] !== '<' || $type[strlen($type) - 1] !== '>') {
+                        $this->printError("Wrong vector subtype in $type");
+                        return '';
+                    }
+                    return 'std::vector<'.$this->getTypeName(substr($type, 7, -1)).'>';
+                }
+
+                if (preg_match('/[^A-Za-z0-9.]/', $type)) {
+                    $this->printError("Wrong type $type");
+                    return '';
+                }
+                return 'object_ptr<'.$this->getClassName($type).'>';
+        }
+    }
+
+    protected function getBaseClassName($is_function)
+    {
+        return $is_function ? 'Function' : 'Object';
+    }
+
+    protected function needRemoveLine($line)
+    {
+        $line = trim($line);
+        return strpos($line, '/**') === 0 || strpos($line, '*') === 0 || strpos($line, '///') === 0;
+    }
+
+    protected function needSkipLine($line)
+    {
+        $tline = trim($line);
+        return empty($tline) || $tline[0] === '}' || $tline === 'public:' || strpos($line, '#pragma ') === 0 ||
+            strpos($line, '#include <') === 0 || strpos($tline, 'return ') === 0 || strpos($tline, 'namespace') === 0 ||
+            preg_match('/class [A-Za-z0-9_]*;/', $line) || $tline === 'if (value == nullptr) {' ||
+            strpos($line, 'JNIEnv') || strpos($line, 'jfieldID') || $tline === 'virtual ~Object() {' ||
+            $tline === 'virtual void store(TlStorerToString &s, const char *field_name) const = 0;';
+    }
+
+    protected function isHeaderLine($line)
+    {
+        return strpos($line, 'template <') === 0;
+    }
+
+    protected function extractClassName($line)
+    {
+        if (strpos($line, 'class ') === 0) {
+            return explode(' ', trim($line))[1];
+        }
+        return '';
+    }
+
+    protected function fixLine($line)
+    {
+        if (strpos($line, 'ID = ') > 0 || strpos($line, 'ReturnType = ') > 0 || strpos($line, 'using BaseObject = ') === 0) {
+            return substr($line, 0, strpos($line, '='));
+        }
+        if (strpos($line, 'class Function: ') === 0) {
+            return 'class Function';
+        }
+        if (strpos($line, 'class Object {') === 0 || strpos($line, 'class Object: public TlObject {') === 0) {
+            return 'class Object';
+        }
+
+        return $line;
+    }
+
+    protected function addGlobalDocumentation()
+    {
+        $this->addDocumentation('#include "td/tl/TlObject.h"', <<<EOT
+/**
+ * \\file
+ * Contains declarations of all functions and types which represent a public TDLib interface.
+ */
+EOT
+);
+
+        $this->addDocumentation('using BaseObject', <<<EOT
+/**
+ * This class is a base class for all TDLib API classes and functions.
+ */
+EOT
+);
+
+        $this->addDocumentation('using object_ptr = ::td::tl_object_ptr<Type>;', <<<EOT
+/**
+ * A smart wrapper to store a pointer to a TDLib API object. Can be treated as an analogue of std::unique_ptr.
+ */
+EOT
+);
+
+        $this->addDocumentation('object_ptr<Type> make_object(Args &&... args) {', <<<EOT
+/**
+ * A function to create a dynamically allocated TDLib API object. Can be treated as an analogue of std::make_unique.
+ * Usage example:
+ * \\code
+ * auto get_authorization_state_request = td::td_api::make_object<td::td_api::getAuthorizationState>();
+ * auto message_text = td::td_api::make_object<td::td_api::formattedText>("Hello, world!!!",
+ *                     std::vector<td::td_api::object_ptr<td::td_api::textEntities>>());
+ * auto send_message_request = td::td_api::make_object<td::td_api::sendMessage>(chat_id, 0, false, false, nullptr,
+ *      td::td_api::make_object<td::td_api::inputMessageText>(std::move(message_text), false, true));
+ * \\endcode
+ *
+ * \\tparam Type Type of an object to construct.
+ * \\param[in] args Arguments to pass to the object constructor.
+ * \\return Wrapped pointer to the created object.
+ */
+EOT
+);
+
+        $this->addDocumentation('object_ptr<ToType> move_object_as(FromType &&from) {', <<<EOT
+/**
+ * A function to cast a wrapped in td::td_api::object_ptr TDLib API object to its subclass or superclass.
+ * Casting an object to an incorrect type will lead to undefined bejaviour.
+ * Usage example:
+ * \\code
+ * td::td_api::object_ptr<td::td_api::callState> call_state = ...;
+ * switch (call_state->get_id()) {
+ *   case td::td_api::callStatePending::ID: {
+ *     auto state = td::td_api::move_object_as<td::td_api::callStatePending>(call_state);
+ *     // use state
+ *     break;
+ *   }
+ *   case td::td_api::callStateExchangingKeys::ID: {
+ *     // no additional fields, no casting is needed
+ *     break;
+ *   }
+ *   case td::td_api::callStateReady::ID: {
+ *     auto state = td::td_api::move_object_as<td::td_api::callStateReady>(call_state);
+ *     // use state
+ *     break;
+ *   }
+ *   case td::td_api::callStateHangingUp::ID: {
+ *     // no additional fields, no casting is needed
+ *     break;
+ *   }
+ *   case td::td_api::callStateDiscarded::ID: {
+ *     auto state = td::td_api::move_object_as<td::td_api::callStateDiscarded>(call_state);
+ *     // use state
+ *     break;
+ *   }
+ *   case td::td_api::callStateError::ID: {
+ *     auto state = td::td_api::move_object_as<td::td_api::callStateError>(call_state);
+ *     // use state
+ *     break;
+ *   }
+ *   default:
+ *     assert(false);
+ * }
+ * \\endcode
+ *
+ * \\tparam ToType Type of a TDLib API object to move to.
+ * \\tparam FromType Type of a TDLib API object to move from, this is auto-deduced.
+ * \\param[in] from Wrapped in td::td_api::object_ptr pointer to a TDLib API object.
+ */
+EOT
+);
+
+        $this->addDocumentation('std::string to_string(const BaseObject &value);', <<<EOT
+/**
+ * Returns a string representation of the TDLib API object.
+ * \\param[in] value The object.
+ * \\return Object string representation.
+ */
+EOT
+);
+
+        $this->addDocumentation('std::string to_string(const object_ptr<T> &value) {', <<<EOT
+/**
+ * Returns a string representation of the TDLib API object.
+ * \\tparam T Object type, auto-deduced.
+ * \\param[in] value The object.
+ * \\return Object string representation.
+ */
+EOT
+);
+
+        $this->addDocumentation('  void store(TlStorerToString &s, const char *field_name) const final;', <<<EOT
+  /**
+   * Helper function for to_string method. Appends string representation of the object to the storer.
+   * \\param[in] s Storer to which object string representation will be appended.
+   * \\param[in] field_name Object field_name if applicable.
+   */
+EOT
+);
+
+        $this->addDocumentation('class Object', <<<EOT
+/**
+ * This class is a base class for all TDLib API classes.
+ */
+EOT
+);
+
+        $this->addDocumentation('class Function', <<<EOT
+/**
+ * This class is a base class for all TDLib API functions.
+ */
+EOT
+);
+
+        $this->addDocumentation('  static const std::int32_t ID', <<<EOT
+  /// Identifier uniquely determining a type of the object.
+EOT
+);
+
+        $this->addDocumentation('  virtual std::int32_t get_id() const = 0;', <<<EOT
+  /**
+   * Returns identifier uniquely determining a type of the object.
+   */
+EOT
+);
+
+        $this->addDocumentation('  std::int32_t get_id() const final {', <<<EOT
+  /**
+   * Returns identifier uniquely determining a type of the object.
+   * \\return this->ID.
+   */
+EOT
+);
+
+        $this->addDocumentation('  using ReturnType', <<<EOT
+  /// Typedef for the type returned by the function.
+EOT
+);
+    }
+
+    protected function addAbstractClassDocumentation($class_name, $documentation)
+    {
+        $this->addDocumentation("class $class_name: public Object {", <<<EOT
+/**
+ * This class is an abstract base class.
+ * $documentation
+ */
+EOT
+);
+    }
+
+    protected function addClassDocumentation($class_name, $base_class_name, $description, $return_type)
+    {
+        $return_type_description = $return_type ? PHP_EOL.' *'.PHP_EOL." * Returns $return_type." : '';
+
+        $this->addDocumentation("class $class_name final : public $base_class_name {", <<<EOT
+/**
+ * $description$return_type_description
+ */
+EOT
+);
+    }
+
+    protected function addFieldDocumentation($class_name, $field_name, $type_name, $field_info, $may_be_null)
+    {
+        $this->addDocumentation($class_name."  $type_name $field_name;", <<<EOT
+  /// $field_info
+EOT
+);
+    }
+
+    protected function addDefaultConstructorDocumentation($class_name)
+    {
+        $this->addDocumentation("  $class_name();", <<<EOT
+  /**
+   * Default constructor. All fields will be value-initilaized.
+   */
+EOT
+);
+    }
+
+    protected function addFullConstructorDocumentation($class_name, $known_fields, $info)
+    {
+        $explicit = count($known_fields) === 1 ? 'explicit ' : '';
+        $full_constructor = "  $explicit$class_name(";
+        $colon = '';
+        foreach ($known_fields as $name => $type) {
+            $full_constructor .= $colon.$this->getParameterTypeName($type).$this->getFieldName($name, $class_name);
+            $colon = ', ';
+        }
+        $full_constructor .= ');';
+
+        $full_doc = <<<EOT
+  /**
+   * Constructor for initialization of all fields.
+   *
+
+EOT;
+        foreach ($known_fields as $name => $type) {
+            $full_doc .= '   * \\param[in] '.$this->getFieldName($name, $class_name).' '.$info[$name].PHP_EOL;
+        }
+        $full_doc .= '   */';
+        $this->addDocumentation($full_constructor, $full_doc);
+    }
+}
+
+$generator = new DoxygenTlDocumentationGenerator();
+$generator->generate($argv[1], $argv[2]);
diff --git a/libs/tdlib/td/td/generate/JavadocTlDocumentationGenerator.php b/libs/tdlib/td/td/generate/JavadocTlDocumentationGenerator.php
new file mode 100644
index 0000000000..6cf170694f
--- /dev/null
+++ b/libs/tdlib/td/td/generate/JavadocTlDocumentationGenerator.php
@@ -0,0 +1,260 @@
+<?php
+
+require_once 'TlDocumentationGenerator.php';
+
+class JavadocTlDocumentationGenerator extends TlDocumentationGenerator
+{
+    private $nullable_type;
+    private $nullable_annotation;
+    private $java_version;
+
+    protected function escapeDocumentation($doc)
+    {
+        $doc = htmlspecialchars($doc);
+        $doc = str_replace('*/', '*&#47;', $doc);
+        $doc = preg_replace_callback('/_([A-Za-z])/', function ($matches) {return strtoupper($matches[1]);}, $doc);
+        return $doc;
+    }
+
+    protected function getFieldName($name, $class_name)
+    {
+        if (substr($name, 0, 6) === 'param_') {
+            $name = substr($name, 6);
+        }
+        return preg_replace_callback('/_([A-Za-z])/', function ($matches) {return strtoupper($matches[1]);}, trim($name));
+    }
+
+    protected function getClassName($type)
+    {
+        return implode(array_map('ucfirst', explode('.', trim($type, "\r\n ;"))));
+    }
+
+    protected function getTypeName($type)
+    {
+        switch ($type) {
+            case 'Bool':
+                return 'boolean';
+            case 'int32':
+                return 'int';
+            case 'int53':
+            case 'int64':
+                return 'long';
+            case 'double':
+                return $type;
+            case 'string':
+                return 'String';
+            case 'bytes':
+                return 'byte[]';
+            case 'bool':
+            case 'int':
+            case 'long':
+            case 'Int':
+            case 'Long':
+            case 'Int32':
+            case 'Int53':
+            case 'Int64':
+            case 'Double':
+            case 'String':
+            case 'Bytes':
+                $this->printError("Wrong type $type");
+                return '';
+            default:
+                if (substr($type, 0, 6) === 'vector') {
+                    if ($type[6] !== '<' || $type[strlen($type) - 1] !== '>') {
+                        $this->printError("Wrong vector subtype in $type");
+                        return '';
+                    }
+                    return $this->getTypeName(substr($type, 7, -1)).'[]';
+                }
+
+                if (preg_match('/[^A-Za-z0-9.]/', $type)) {
+                    $this->printError("Wrong type $type");
+                    return '';
+                }
+                return $this->getClassName($type);
+        }
+    }
+
+    protected function getBaseClassName($is_function)
+    {
+        return $is_function ? 'Function' : 'Object';
+    }
+
+    protected function needRemoveLine($line)
+    {
+        return strpos(trim($line), '/**') === 0 || strpos(trim($line), '*') === 0 ||
+            ($this->nullable_type && strpos($line, $this->nullable_type) > 0);
+    }
+
+    protected function needSkipLine($line)
+    {
+        $line = trim($line);
+        return strpos($line, 'public') !== 0 && !$this->isHeaderLine($line);
+    }
+
+    protected function isHeaderLine($line)
+    {
+        return trim($line) === '@Override';
+    }
+
+    protected function extractClassName($line)
+    {
+        if (strpos($line, 'public static class ') > 0) {
+            return explode(' ', trim($line))[3];
+        }
+        return '';
+    }
+
+    protected function fixLine($line)
+    {
+        if (strpos($line, 'CONSTRUCTOR = ') > 0) {
+            return substr($line, 0, strpos($line, '='));
+        }
+
+        return $this->nullable_annotation ? str_replace($this->nullable_annotation.' ', '', $line) : $line;
+    }
+
+    protected function addGlobalDocumentation()
+    {
+        if ($this->nullable_type) {
+            $nullable_type_import = "import $this->nullable_type;".PHP_EOL;
+        } else {
+            $nullable_type_import = '';
+        }
+
+        $this->addDocumentation('public class TdApi {', <<<EOT
+$nullable_type_import/**
+ * This class contains as static nested classes all other TDLib interface
+ * type-classes and function-classes.
+ * <p>
+ * It has no inner classes, functions or public members.
+ */
+EOT
+);
+
+        $this->addDocumentation('    public abstract static class Object {', <<<EOT
+    /**
+     * This class is a base class for all TDLib interface classes.
+     */
+EOT
+);
+
+        $this->addDocumentation('        public abstract int getConstructor();', <<<EOT
+        /**
+         * @return identifier uniquely determining type of the object.
+         */
+EOT
+);
+
+        $this->addDocumentation('        public native String toString();', <<<EOT
+        /**
+         * @return string representation of the object.
+         */
+EOT
+);
+
+        $this->addDocumentation('    public abstract static class Function extends Object {', <<<EOT
+    /**
+     * This class is a base class for all TDLib interface function-classes.
+     */
+EOT
+);
+
+        $this->addDocumentation('        public static final int CONSTRUCTOR', <<<EOT
+        /**
+         * Identifier uniquely determining type of the object.
+         */
+EOT
+);
+
+        $this->addDocumentation('        public int getConstructor() {', <<<EOT
+        /**
+         * @return this.CONSTRUCTOR
+         */
+EOT
+);
+    }
+
+    protected function addAbstractClassDocumentation($class_name, $documentation)
+    {
+        $this->addDocumentation("    public abstract static class $class_name extends Object {", <<<EOT
+    /**
+     * This class is an abstract base class.
+     * $documentation
+     */
+EOT
+);
+    }
+
+    protected function addClassDocumentation($class_name, $base_class_name, $description, $return_type)
+    {
+        $return_type_description = $return_type ? PHP_EOL.'     *'.PHP_EOL."     * <p> Returns {@link $return_type $return_type} </p>" : '';
+
+        $this->addDocumentation("    public static class $class_name extends $base_class_name {", <<<EOT
+    /**
+     * $description$return_type_description
+     */
+EOT
+);
+    }
+
+    protected function addFieldDocumentation($class_name, $field_name, $type_name, $field_info, $may_be_null)
+    {
+        $full_line = $class_name."        public $type_name $field_name;";
+        $this->addDocumentation($full_line, <<<EOT
+        /**
+         * $field_info
+         */
+EOT
+);
+        if ($may_be_null && $this->nullable_annotation && ($this->java_version >= 8 || substr($type_name, -1) != ']')) {
+            $this->addLineReplacement($full_line, "        public $this->nullable_annotation $type_name $field_name;".PHP_EOL);
+        }
+    }
+
+    protected function addDefaultConstructorDocumentation($class_name)
+    {
+        $this->addDocumentation("        public $class_name() {", <<<EOT
+        /**
+         * Default constructor.
+         */
+EOT
+);
+    }
+
+    protected function addFullConstructorDocumentation($class_name, $known_fields, $info)
+    {
+        $full_constructor = "        public $class_name(";
+        $colon = '';
+        foreach ($known_fields as $name => $type) {
+            $full_constructor .= $colon.$this->getTypeName($type).' '.$this->getFieldName($name, $class_name);
+            $colon = ', ';
+        }
+        $full_constructor .= ') {';
+
+        $full_doc = <<<EOT
+        /**
+         * Constructor for initialization of all fields.
+         *
+
+EOT;
+        foreach ($known_fields as $name => $type) {
+            $full_doc .= '         * @param '.$this->getFieldName($name, $class_name).' '.$info[$name].PHP_EOL;
+        }
+        $full_doc .= '         */';
+        $this->addDocumentation($full_constructor, $full_doc);
+    }
+
+    public function __construct($nullable_type, $nullable_annotation, $java_version) {
+        $this->nullable_type = trim($nullable_type);
+        $this->nullable_annotation = trim($nullable_annotation);
+        $this->java_version = intval($java_version);
+    }
+}
+
+$nullable_type = isset($argv[3]) ? $argv[3] : '';
+$nullable_annotation = isset($argv[4]) ? $argv[4] : '';
+$java_version = isset($argv[5]) ? intval($argv[5]) : 7;
+
+$generator = new JavadocTlDocumentationGenerator($nullable_type, $nullable_annotation, $java_version);
+$generator->generate($argv[1], $argv[2]);
diff --git a/libs/tdlib/td/td/generate/TlDocumentationGenerator.php b/libs/tdlib/td/td/generate/TlDocumentationGenerator.php
new file mode 100644
index 0000000000..11a281ce38
--- /dev/null
+++ b/libs/tdlib/td/td/generate/TlDocumentationGenerator.php
@@ -0,0 +1,306 @@
+<?php
+
+abstract class TlDocumentationGenerator
+{
+    private $current_line = '';
+    private $documentation = array();
+    private $line_replacement = array();
+
+    final protected function printError($error)
+    {
+        fwrite(STDERR, "$error near line \"".rtrim($this->current_line)."\"\n");
+    }
+
+    final protected function addDocumentation($code, $doc) {
+        if (isset($this->documentation[$code])) {
+            $this->printError("Duplicate documentation for \"$code\"");
+        }
+
+        $this->documentation[$code] = $doc;
+        // $this->printError($code);
+    }
+
+    final protected function addLineReplacement($line, $new_line) {
+        if (isset($this->line_replacement[$line])) {
+            $this->printError("Duplicate line replacement for \"$line\"");
+        }
+
+        $this->line_replacement[$line] = $new_line;
+    }
+
+    final protected function addDot($str) {
+        if (!$str) {
+            return '';
+        }
+
+        $len = strlen($str);
+        if ($str[$len - 1] === '.') {
+            return $str;
+        }
+
+        if ($str[$len - 1] === ')') {
+            // trying to place dot inside the brackets
+            $bracket_count = 1;
+            for ($pos = $len - 2; $pos >= 0; $pos--) {
+                if ($str[$pos] === ')') {
+                    $bracket_count++;
+                }
+                if ($str[$pos] === '(') {
+                    $bracket_count--;
+                    if ($bracket_count === 0) {
+                        break;
+                    }
+                }
+            }
+            if ($bracket_count === 0) {
+                if (ctype_upper($str[$pos + 1])) {
+                    return substr($str, 0, -1).'.)';
+                }
+            } else {
+                $this->printError("Unmatched bracket");
+            }
+        }
+        return $str.'.';
+    }
+
+    abstract protected function escapeDocumentation($doc);
+
+    abstract protected function getFieldName($name, $class_name);
+
+    abstract protected function getClassName($name);
+
+    abstract protected function getTypeName($type);
+
+    abstract protected function getBaseClassName($is_function);
+
+    abstract protected function needRemoveLine($line);
+
+    abstract protected function needSkipLine($line);
+
+    abstract protected function isHeaderLine($line);
+
+    abstract protected function extractClassName($line);
+
+    abstract protected function fixLine($line);
+
+    abstract protected function addGlobalDocumentation();
+
+    abstract protected function addAbstractClassDocumentation($class_name, $value);
+
+    abstract protected function addClassDocumentation($class_name, $base_class_name, $description, $return_type);
+
+    abstract protected function addFieldDocumentation($class_name, $field_name, $type_name, $field_info, $may_be_null);
+
+    abstract protected function addDefaultConstructorDocumentation($class_name);
+
+    abstract protected function addFullConstructorDocumentation($class_name, $known_fields, $info);
+
+    public function generate($tl_scheme_file, $source_file)
+    {
+        $lines = array_filter(array_map('trim', file($tl_scheme_file)));
+        $description = '';
+        $current_class = '';
+        $is_function = false;
+        $need_class_description = false;
+
+        $this->addGlobalDocumentation();
+
+        foreach ($lines as $line) {
+            $this->current_line = $line;
+            if ($line === '---types---') {
+                $is_function = false;
+            } elseif ($line === '---functions---') {
+                $is_function = true;
+                $current_class = '';
+                $need_class_description = false;
+            } elseif ($line[0] === '/') {
+                if ($line[1] !== '/') {
+                    $this->printError('Wrong comment');
+                    continue;
+                }
+                if ($line[2] === '@' || $line[2] === '-') {
+                    $description .= trim(substr($line, 2 + intval($line[2] === '-'))).' ';
+                } else {
+                    $this->printError('Unexpected comment');
+                }
+            } elseif (strpos($line, '? =') || strpos($line, ' = Vector t;') || $line === 'boolFalse = Bool;' ||
+                      $line === 'boolTrue = Bool;' || $line === 'bytes = Bytes;' || $line === 'int32 = Int32;' ||
+                      $line === 'int53 = Int53;'|| $line === 'int64 = Int64;') {
+                // skip built-in types
+                continue;
+            } else {
+                $description = trim($description);
+                if ($description[0] !== '@') {
+                    $this->printError('Wrong description begin');
+                }
+
+                $docs = explode('@', $description);
+                array_shift($docs);
+                $info = array();
+
+                foreach ($docs as $doc) {
+                    list($key, $value) = explode(' ', $doc, 2);
+                    $value = trim($value);
+
+                    if ($need_class_description) {
+                        if ($key === 'description') {
+                            $need_class_description = false;
+
+                            $value = $this->addDot($value);
+
+                            $this->addAbstractClassDocumentation($current_class, $value);
+                            continue;
+                        } else {
+                            $this->printError('Expected abstract class description');
+                        }
+                    }
+
+                    if ($key === 'class') {
+                        $current_class = $this->getClassName($value);
+                        $need_class_description = true;
+
+                        if ($is_function) {
+                            $this->printError('Unexpected class definition');
+                        }
+                    } else {
+                        if (isset($info[$key])) {
+                            $this->printError("Duplicate info about `$key`");
+                        }
+                        $info[$key] = trim($value);
+                    }
+                }
+
+                if (substr_count($line, '=') !== 1) {
+                    $this->printError("Wrong '=' count");
+                    continue;
+                }
+
+                list($fields, $type) = explode('=', $line);
+                $type = $this->getClassName($type);
+                $fields = explode(' ', trim($fields));
+                $class_name = $this->getClassName(array_shift($fields));
+
+                if ($type !== $current_class) {
+                    $current_class = '';
+                    $need_class_description = false;
+                }
+
+                if (!$is_function) {
+                    $type_lower = strtolower($type);
+                    $class_name_lower = strtolower($class_name);
+                    if (empty($current_class) === ($type_lower !== $class_name_lower)) {
+                        $this->printError('Wrong constructor name');
+                    }
+                    if (strpos($class_name_lower, $type_lower) !== 0) {
+                        // $this->printError('Wrong constructor name');
+                    }
+                }
+
+                $known_fields = array();
+                foreach ($fields as $field) {
+                    list ($field_name, $field_type) = explode(':', $field);
+                    if (isset($info['param_'.$field_name])) {
+                        $known_fields['param_'.$field_name] = $field_type;
+                        continue;
+                    }
+                    if (isset($info[$field_name])) {
+                        $known_fields[$field_name] = $field_type;
+                        continue;
+                    }
+                    $this->printError("Have no info about field `$field_name`");
+                }
+
+                foreach ($info as $name => $value) {
+                    if (!$value) {
+                        $this->printError("info[$name] for $class_name is empty");
+                    } elseif ($value[0] < 'A' || $value[0] > 'Z') {
+                        $this->printError("info[$name] for $class_name doesn't begins with capital letter");
+                    }
+                }
+
+                foreach (array_diff_key($info, $known_fields) as $field_name => $field_info) {
+                    if ($field_name !== 'description') {
+                        $this->printError("Have info about unexisted field `$field_name`");
+                    }
+                }
+
+                if (!$info['description']) {
+                    $this->printError("Have no description for class `$class_name`");
+                }
+
+                foreach ($info as &$v) {
+                    $v = $this->escapeDocumentation($this->addDot($v));
+                }
+
+                $base_class_name = $current_class ?: $this->getBaseClassName($is_function);
+                $this->addClassDocumentation($class_name, $base_class_name, $info['description'], $is_function ? $this->getTypeName($type) : '');
+
+                foreach ($known_fields as $name => $type) {
+                    $may_be_null = stripos($info[$name], 'may be null') !== false;
+                    $this->addFieldDocumentation($class_name, $this->getFieldName($name, $class_name), $this->getTypeName($type), $info[$name], $may_be_null);
+                }
+
+                $this->addDefaultConstructorDocumentation($class_name);
+
+                if ($known_fields) {
+                    $this->addFullConstructorDocumentation($class_name, $known_fields, $info);
+                }
+
+                $description = '';
+            }
+        }
+
+        $lines = file($source_file);
+        $result = '';
+        $current_class = '';
+        $current_headers = '';
+        foreach ($lines as $line) {
+            $this->current_line = $line;
+            if ($this->needRemoveLine($line)) {
+                continue;
+            }
+            if ($this->needSkipLine($line)) {
+                $result .= $current_headers.$line;
+                $current_headers = '';
+                continue;
+            }
+            if ($this->isHeaderLine($line)) {
+                $current_headers .= $line;
+                continue;
+            }
+
+            $current_class = $this->extractClassName($line) ?: $current_class;
+
+            $fixed_line = rtrim($this->fixLine($line));
+
+            $doc = '';
+            if (isset($this->documentation[$fixed_line])) {
+                $doc = $this->documentation[$fixed_line];
+                // unset($this->documentation[$fixed_line]);
+            } elseif (isset($this->documentation[$current_class.$fixed_line])) {
+                $doc = $this->documentation[$current_class.$fixed_line];
+                // unset($this->documentation[$current_class.$fixed_line]);
+            } else {
+                $this->printError('Have no docs for "'.$fixed_line.'"');
+            }
+            if ($doc) {
+                $result .= $doc."\n";
+            }
+            if (isset($this->line_replacement[$fixed_line])) {
+                $line = $this->line_replacement[$fixed_line];
+            } elseif (isset($this->line_replacement[$current_class.$fixed_line])) {
+                $line = $this->line_replacement[$current_class.$fixed_line];
+            }
+            $result .= $current_headers.$line;
+            $current_headers = '';
+        }
+
+        if (file_get_contents($source_file) !== $result) {
+            file_put_contents($source_file, $result);
+        }
+
+        if (count($this->documentation)) {
+            // $this->printError('Have unused docs '.print_r(array_keys($this->documentation), true));
+        }
+    }
+}
diff --git a/libs/tdlib/td/td/generate/generate_c.cpp b/libs/tdlib/td/td/generate/generate_c.cpp
new file mode 100644
index 0000000000..841d1b366c
--- /dev/null
+++ b/libs/tdlib/td/td/generate/generate_c.cpp
@@ -0,0 +1,20 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_writer_c.h"
+
+#include "td/tl/tl_config.h"
+#include "td/tl/tl_generate.h"
+
+int main() {
+  td::tl::tl_config config_td = td::tl::read_tl_config_from_file("scheme/td_api.tlo");
+  td::tl::write_tl_to_file(config_td, "auto/td/telegram/td_tdc_api.h",
+                           td::TlWriterCCommon("TdApi", 1, "#include \"td/telegram/td_api.h\"\n"));
+  td::tl::write_tl_to_file(config_td, "auto/td/telegram/td_tdc_api_inner.h",
+                           td::TlWriterCCommon("TdApi", -1, "#include \"td/telegram/td_api.h\"\n"));
+  td::tl::write_tl_to_file(config_td, "auto/td/telegram/td_tdc_api.cpp",
+                           td::TlWriterCCommon("TdApi", 0, "#include \"td/telegram/td_api.h\"\n"));
+}
diff --git a/libs/tdlib/td/td/generate/generate_common.cpp b/libs/tdlib/td/td/generate/generate_common.cpp
new file mode 100644
index 0000000000..8759c40550
--- /dev/null
+++ b/libs/tdlib/td/td/generate/generate_common.cpp
@@ -0,0 +1,47 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_writer_cpp.h"
+#include "tl_writer_h.h"
+#include "tl_writer_hpp.h"
+#include "tl_writer_jni_cpp.h"
+#include "tl_writer_jni_h.h"
+
+#include "td/tl/tl_config.h"
+#include "td/tl/tl_generate.h"
+
+#include <string>
+#include <vector>
+
+template <class WriterCpp = td::TD_TL_writer_cpp, class WriterH = td::TD_TL_writer_h,
+          class WriterHpp = td::TD_TL_writer_hpp>
+static void generate_cpp(const std::string &directory, const std::string &tl_name, const std::string &string_type,
+                         const std::string &bytes_type, const std::vector<std::string> &ext_cpp_includes,
+                         const std::vector<std::string> &ext_h_includes) {
+  std::string path = directory + "/" + tl_name;
+  td::tl::tl_config config = td::tl::read_tl_config_from_file("scheme/" + tl_name + ".tlo");
+  td::tl::write_tl_to_file(config, path + ".cpp", WriterCpp(tl_name, string_type, bytes_type, ext_cpp_includes));
+  td::tl::write_tl_to_file(config, path + ".h", WriterH(tl_name, string_type, bytes_type, ext_h_includes));
+  td::tl::write_tl_to_file(config, path + ".hpp", WriterHpp(tl_name, string_type, bytes_type));
+}
+
+int main() {
+  generate_cpp<>("auto/td/telegram", "telegram_api", "std::string", "BufferSlice",
+                 {"\"td/tl/tl_object_parse.h\"", "\"td/tl/tl_object_store.h\""}, {"\"td/utils/buffer.h\""});
+
+  generate_cpp<>("auto/td/telegram", "secret_api", "std::string", "BufferSlice",
+                 {"\"td/tl/tl_object_parse.h\"", "\"td/tl/tl_object_store.h\""}, {"\"td/utils/buffer.h\""});
+
+  generate_cpp<>("auto/td/mtproto", "mtproto_api", "Slice", "Slice",
+                 {"\"td/tl/tl_object_parse.h\"", "\"td/tl/tl_object_store.h\""}, {"\"td/utils/Slice.h\""});
+
+#ifdef TD_ENABLE_JNI
+  generate_cpp<td::TD_TL_writer_jni_cpp, td::TD_TL_writer_jni_h>(
+      "auto/td/telegram", "td_api", "std::string", "std::string", {"\"td/tl/tl_jni_object.h\""}, {"<string>"});
+#else
+  generate_cpp<>("auto/td/telegram", "td_api", "std::string", "std::string", {}, {"<string>"});
+#endif
+}
diff --git a/libs/tdlib/td/td/generate/generate_dotnet.cpp b/libs/tdlib/td/td/generate/generate_dotnet.cpp
new file mode 100644
index 0000000000..59e36778fd
--- /dev/null
+++ b/libs/tdlib/td/td/generate/generate_dotnet.cpp
@@ -0,0 +1,23 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_writer_dotnet.h"
+
+#include "td/tl/tl_config.h"
+#include "td/tl/tl_generate.h"
+
+int main(int argc, char *argv[]) {
+  if (argc < 2) {
+    return 1;
+  }
+
+  td::tl::tl_config config_td = td::tl::read_tl_config_from_file(argv[1]);
+
+  td::tl::write_tl_to_file(config_td, "auto/td/telegram/TdDotNetApi.cpp",
+                           td::tl::TlWriterDotNet("TdApi", false, "#include \"td/telegram/TdDotNetApi.h\"\n\n"));
+  td::tl::write_tl_to_file(config_td, "auto/td/telegram/TdDotNetApi.h",
+                           td::tl::TlWriterDotNet("TdApi", true, ""));
+}
diff --git a/libs/tdlib/td/td/generate/generate_java.cpp b/libs/tdlib/td/td/generate/generate_java.cpp
new file mode 100644
index 0000000000..0dd968b2fa
--- /dev/null
+++ b/libs/tdlib/td/td/generate/generate_java.cpp
@@ -0,0 +1,29 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_writer_java.h"
+
+#include "td/tl/tl_config.h"
+#include "td/tl/tl_generate.h"
+
+#include <algorithm>
+#include <string>
+
+int main(int argc, char *argv[]) {
+  if (argc < 5) {
+    return 1;
+  }
+
+  std::string api_name = argv[1];
+  std::string source = argv[2];
+  std::string destination = argv[3];
+  std::string package = argv[4];
+  std::string package_name = package;
+  std::replace(package_name.begin(), package_name.end(), '/', '.');
+  destination += "/" + package + "/" + api_name + ".java";
+  td::tl::write_tl_to_file(td::tl::read_tl_config_from_file(source), destination,
+                           td::TD_TL_writer_java(api_name, package_name));
+}
diff --git a/libs/tdlib/td/td/generate/generate_json.cpp b/libs/tdlib/td/td/generate/generate_json.cpp
new file mode 100644
index 0000000000..f03f5eeae8
--- /dev/null
+++ b/libs/tdlib/td/td/generate/generate_json.cpp
@@ -0,0 +1,14 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_json_converter.h"
+
+#include "td/tl/tl_config.h"
+#include "td/tl/tl_generate.h"
+
+int main() {
+  td::gen_json_converter(td::tl::read_tl_config_from_file("scheme/td_api.tlo"), "td/telegram/td_api_json");
+}
diff --git a/libs/tdlib/td/td/generate/remove_documentation.cpp b/libs/tdlib/td/td/generate/remove_documentation.cpp
new file mode 100644
index 0000000000..d690f0ba8b
--- /dev/null
+++ b/libs/tdlib/td/td/generate/remove_documentation.cpp
@@ -0,0 +1,23 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/tl/tl_file_utils.h"
+
+#include <cstdio>
+#include <cstdlib>
+#include <string>
+
+int main(int argc, char *argv[]) {
+  for (int i = 1; i < argc; i++) {
+    std::string file_name = argv[i];
+    std::string old_contents = td::tl::get_file_contents(file_name, "rb");
+    std::string new_contents = td::tl::remove_documentation(old_contents);
+    if (new_contents != old_contents && !td::tl::put_file_contents(file_name, "wb", new_contents)) {
+      std::fprintf(stderr, "Can't write file %s\n", file_name.c_str());
+      std::abort();
+    }
+  }
+}
diff --git a/libs/tdlib/td/td/generate/scheme/mtproto_api.tl b/libs/tdlib/td/td/generate/scheme/mtproto_api.tl
new file mode 100644
index 0000000000..b89e9bde3f
--- /dev/null
+++ b/libs/tdlib/td/td/generate/scheme/mtproto_api.tl
@@ -0,0 +1,91 @@
+int ? = Int;
+long ? = Long;
+double ? = Double;
+string ? = String;
+
+dummyHttpWait = HttpWait;
+
+vector {t:Type} # [ t ] = Vector t;
+
+int128 4*[ int ] = Int128;
+int256 8*[ int ] = Int256;
+
+resPQ#05162463 nonce:int128 server_nonce:int128 pq:string server_public_key_fingerprints:Vector<long> = ResPQ;
+
+p_q_inner_data#83c95aec pq:string p:string q:string nonce:int128 server_nonce:int128 new_nonce:int256 = P_Q_inner_data;
+p_q_inner_data_temp#3c6a84d4 pq:string p:string q:string nonce:int128 server_nonce:int128 new_nonce:int256 expires_in:int = P_Q_inner_data;
+
+server_DH_params_fail#79cb045d nonce:int128 server_nonce:int128 new_nonce_hash:int128 = Server_DH_Params;
+server_DH_params_ok#d0e8075c nonce:int128 server_nonce:int128 encrypted_answer:string = Server_DH_Params;
+
+server_DH_inner_data#b5890dba nonce:int128 server_nonce:int128 g:int dh_prime:string g_a:string server_time:int = Server_DH_inner_data;
+
+client_DH_inner_data#6643b654 nonce:int128 server_nonce:int128 retry_id:long g_b:string = Client_DH_Inner_Data;
+
+dh_gen_ok#3bcbf734 nonce:int128 server_nonce:int128 new_nonce_hash1:int128 = Set_client_DH_params_answer;
+dh_gen_retry#46dc1fb9 nonce:int128 server_nonce:int128 new_nonce_hash2:int128 = Set_client_DH_params_answer;
+dh_gen_fail#a69dae02 nonce:int128 server_nonce:int128 new_nonce_hash3:int128 = Set_client_DH_params_answer;
+
+bind_auth_key_inner#75a3f765 nonce:long temp_auth_key_id:long perm_auth_key_id:long temp_session_id:long expires_at:int
+= BindAuthKeyInner;
+
+//rpc_result#f35c6d01 req_msg_id:long result:string = RpcResult;
+rpc_error#2144ca19 error_code:int error_message:string = RpcError;
+
+rpc_answer_unknown#5e2ad36e = RpcDropAnswer;
+rpc_answer_dropped_running#cd78e586 = RpcDropAnswer;
+rpc_answer_dropped#a43ad8b7 msg_id:long seq_no:int bytes:int = RpcDropAnswer;
+
+future_salt#0949d9dc valid_since:int valid_until:int salt:long = FutureSalt;
+future_salts#ae500895 req_msg_id:long now:int salts:vector<future_salt> = FutureSalts;
+
+pong#347773c5 msg_id:long ping_id:long = Pong;
+
+destroy_session_ok#e22045fc session_id:long = DestroySessionRes;
+destroy_session_none#62d350c9 session_id:long = DestroySessionRes;
+
+new_session_created#9ec20908 first_msg_id:long unique_id:long server_salt:long = NewSession;
+
+//msg_container#73f1f8dc messages:vector<%Message> = MessageContainer;
+//message msg_id:long seqno:int bytes:int body:string = Message;
+//msg_copy#e06046b2 orig_message:Message = MessageCopy;
+
+gzip_packed#3072cfa1 packed_data:string = GzipPacked;
+
+msgs_ack#62d6b459 msg_ids:Vector<long> = MsgsAck;
+
+bad_msg_notification#a7eff811 bad_msg_id:long bad_msg_seqno:int error_code:int = BadMsgNotification;
+bad_server_salt#edab447b bad_msg_id:long bad_msg_seqno:int error_code:int new_server_salt:long = BadMsgNotification;
+
+msg_resend_req#7d861a08 msg_ids:Vector<long> = MsgResendReq;
+msgs_state_req#da69fb52 msg_ids:Vector<long> = MsgsStateReq;
+msgs_state_info#04deb57d req_msg_id:long info:string = MsgsStateInfo;
+msgs_all_info#8cc0d131 msg_ids:Vector<long> info:string = MsgsAllInfo;
+msg_detailed_info#276d3ec6 msg_id:long answer_msg_id:long bytes:int status:int = MsgDetailedInfo;
+msg_new_detailed_info#809db6df answer_msg_id:long bytes:int status:int = MsgDetailedInfo;
+
+rsa_public_key n:string e:string = RSAPublicKey;
+
+---functions---
+
+req_pq_multi#be7e8ef1 nonce:int128 = ResPQ;
+
+req_DH_params#d712e4be nonce:int128 server_nonce:int128 p:string q:string public_key_fingerprint:long encrypted_data:string = Server_DH_Params;
+
+set_client_DH_params#f5045f1f nonce:int128 server_nonce:int128 encrypted_data:string = Set_client_DH_params_answer;
+
+rpc_drop_answer#58e4a740 req_msg_id:long = RpcDropAnswer;
+get_future_salts#b921bd04 num:int = FutureSalts;
+ping#7abe77ec ping_id:long = Pong;
+ping_delay_disconnect#f3427b8c ping_id:long disconnect_delay:int = Pong;
+destroy_session#e7512126 session_id:long = DestroySessionRes;
+
+http_wait#9299359f max_delay:int wait_after:int max_wait:int = HttpWait;
+
+//test.useGzipPacked = GzipPacked;
+//test.useServerDhInnerData = Server_DH_inner_data;
+//test.useNewSessionCreated = NewSession;
+//test.useMsgsAck = MsgsAck;
+//test.useBadMsgNotification = BadMsgNotification;
+
+//test.useOther key:rsa_public_key p_q_data:P_Q_inner_data dh_data:client_DH_inner_data = RpcError;
diff --git a/libs/tdlib/td/td/generate/scheme/mtproto_api.tlo b/libs/tdlib/td/td/generate/scheme/mtproto_api.tlo
new file mode 100644
index 0000000000..6c3583ddb3
--- /dev/null
+++ b/libs/tdlib/td/td/generate/scheme/mtproto_api.tlo
diff --git a/libs/tdlib/td/td/generate/scheme/secret_api.tl b/libs/tdlib/td/td/generate/scheme/secret_api.tl
new file mode 100644
index 0000000000..32db7251f1
--- /dev/null
+++ b/libs/tdlib/td/td/generate/scheme/secret_api.tl
@@ -0,0 +1,115 @@
+int ? = Int;
+long ? = Long;
+double ? = Double;
+string ? = String;
+
+bytes = Bytes;
+
+boolFalse = Bool;
+boolTrue = Bool;
+
+true#3fedd339 = True;
+
+vector {t:Type} # [ t ] = Vector t;
+
+decryptedMessage8#1f814f1f random_id:long random_bytes:bytes message:string media:DecryptedMessageMedia = DecryptedMessage;
+decryptedMessageService8#aa48327d random_id:long random_bytes:bytes action:DecryptedMessageAction = DecryptedMessage;
+decryptedMessageMediaEmpty#89f5c4a = DecryptedMessageMedia;
+decryptedMessageMediaPhoto23#32798a8c thumb:bytes thumb_w:int thumb_h:int w:int h:int size:int key:bytes iv:bytes = DecryptedMessageMedia;
+decryptedMessageMediaVideo8#4cee6ef3 thumb:bytes thumb_w:int thumb_h:int duration:int w:int h:int size:int key:bytes iv:bytes = DecryptedMessageMedia;
+decryptedMessageMediaGeoPoint#35480a59 lat:double long:double = DecryptedMessageMedia;
+decryptedMessageMediaContact#588a0a97 phone_number:string first_name:string last_name:string user_id:int = DecryptedMessageMedia;
+decryptedMessageActionSetMessageTTL#a1733aec ttl_seconds:int = DecryptedMessageAction;
+decryptedMessageMediaDocument23#b095434b thumb:bytes thumb_w:int thumb_h:int file_name:string mime_type:string size:int key:bytes iv:bytes = DecryptedMessageMedia;
+decryptedMessageMediaAudio8#6080758f duration:int size:int key:bytes iv:bytes = DecryptedMessageMedia;
+decryptedMessageActionReadMessages#c4f40be random_ids:Vector<long> = DecryptedMessageAction;
+decryptedMessageActionDeleteMessages#65614304 random_ids:Vector<long> = DecryptedMessageAction;
+decryptedMessageActionScreenshotMessages#8ac1f475 random_ids:Vector<long> = DecryptedMessageAction;
+decryptedMessageActionFlushHistory#6719e45c = DecryptedMessageAction;
+
+// layer 23
+
+decryptedMessage23#204d3878 random_id:long ttl:int message:string media:DecryptedMessageMedia = DecryptedMessage;
+decryptedMessageService#73164160 random_id:long action:DecryptedMessageAction = DecryptedMessage;
+decryptedMessageMediaVideo23#524a415d thumb:bytes thumb_w:int thumb_h:int duration:int mime_type:string w:int h:int size:int key:bytes iv:bytes = DecryptedMessageMedia;
+decryptedMessageMediaAudio#57e0a9cb duration:int mime_type:string size:int key:bytes iv:bytes = DecryptedMessageMedia;
+decryptedMessageLayer#1be31789 random_bytes:bytes layer:int in_seq_no:int out_seq_no:int message:DecryptedMessage = DecryptedMessageLayer;
+
+sendMessageTypingAction#16bf744e = SendMessageAction;
+sendMessageCancelAction#fd5ec8f5 = SendMessageAction;
+sendMessageRecordVideoAction#a187d66f = SendMessageAction;
+sendMessageUploadVideoAction#92042ff7 = SendMessageAction;
+sendMessageRecordAudioAction#d52f73f7 = SendMessageAction;
+sendMessageUploadAudioAction#e6ac8a6f = SendMessageAction;
+sendMessageUploadPhotoAction#990a3c1a = SendMessageAction;
+sendMessageUploadDocumentAction#8faee98e = SendMessageAction;
+sendMessageGeoLocationAction#176f8ba1 = SendMessageAction;
+sendMessageChooseContactAction#628cbc6f = SendMessageAction;
+
+decryptedMessageActionResend#511110b0 start_seq_no:int end_seq_no:int = DecryptedMessageAction;
+decryptedMessageActionNotifyLayer#f3048883 layer:int = DecryptedMessageAction;
+decryptedMessageActionTyping#ccb27641 action:SendMessageAction = DecryptedMessageAction;
+
+decryptedMessageActionRequestKey#f3c9611b exchange_id:long g_a:bytes = DecryptedMessageAction;
+decryptedMessageActionAcceptKey#6fe1735b exchange_id:long g_b:bytes key_fingerprint:long = DecryptedMessageAction;
+decryptedMessageActionAbortKey#dd05ec6b exchange_id:long = DecryptedMessageAction;
+decryptedMessageActionCommitKey#ec2e0b9b exchange_id:long key_fingerprint:long = DecryptedMessageAction;
+decryptedMessageActionNoop#a82fdd63 = DecryptedMessageAction;
+
+documentAttributeImageSize#6c37c15c w:int h:int = DocumentAttribute;
+documentAttributeAnimated#11b58939 = DocumentAttribute;
+documentAttributeSticker23#fb0a5727 = DocumentAttribute;
+documentAttributeVideo#5910cccb duration:int w:int h:int = DocumentAttribute;
+documentAttributeAudio23#51448e5 duration:int = DocumentAttribute;
+documentAttributeFilename#15590068 file_name:string = DocumentAttribute;
+photoSizeEmpty#e17e23c type:string = PhotoSize;
+photoSize#77bfb61b type:string location:FileLocation w:int h:int size:int = PhotoSize;
+photoCachedSize#e9a734fa type:string location:FileLocation w:int h:int bytes:bytes = PhotoSize;
+fileLocationUnavailable#7c596b46 volume_id:long local_id:int secret:long = FileLocation;
+fileLocation#53d69076 dc_id:int volume_id:long local_id:int secret:long = FileLocation;
+decryptedMessageMediaExternalDocument#fa95b0dd id:long access_hash:long date:int mime_type:string size:int thumb:PhotoSize dc_id:int attributes:Vector<DocumentAttribute> = DecryptedMessageMedia;
+
+// layer 45
+
+documentAttributeAudio45#ded218e0 duration:int title:string performer:string = DocumentAttribute;
+
+// layer 46
+
+decryptedMessage46#36b091de flags:# random_id:long ttl:int message:string media:flags.9?DecryptedMessageMedia entities:flags.7?Vector<MessageEntity> via_bot_name:flags.11?string reply_to_random_id:flags.3?long = DecryptedMessage;
+decryptedMessageMediaPhoto#f1fa8d78 thumb:bytes thumb_w:int thumb_h:int w:int h:int size:int key:bytes iv:bytes caption:string = DecryptedMessageMedia;
+decryptedMessageMediaVideo#970c8c0e thumb:bytes thumb_w:int thumb_h:int duration:int mime_type:string w:int h:int size:int key:bytes iv:bytes caption:string = DecryptedMessageMedia;
+decryptedMessageMediaDocument#7afe8ae2 thumb:bytes thumb_w:int thumb_h:int mime_type:string size:int key:bytes iv:bytes attributes:Vector<DocumentAttribute> caption:string = DecryptedMessageMedia;
+documentAttributeSticker#3a556302 alt:string stickerset:InputStickerSet = DocumentAttribute;
+documentAttributeAudio#9852f9c6 flags:# voice:flags.10?true duration:int title:flags.0?string performer:flags.1?string waveform:flags.2?bytes = DocumentAttribute;
+messageEntityUnknown#bb92ba95 offset:int length:int = MessageEntity;
+messageEntityMention#fa04579d offset:int length:int = MessageEntity;
+messageEntityHashtag#6f635b0d offset:int length:int = MessageEntity;
+messageEntityBotCommand#6cef8ac7 offset:int length:int = MessageEntity;
+messageEntityUrl#6ed02538 offset:int length:int = MessageEntity;
+messageEntityEmail#64e475c2 offset:int length:int = MessageEntity;
+messageEntityBold#bd610bc9 offset:int length:int = MessageEntity;
+messageEntityItalic#826f8b60 offset:int length:int = MessageEntity;
+messageEntityCode#28a20571 offset:int length:int = MessageEntity;
+messageEntityPre#73924be0 offset:int length:int language:string = MessageEntity;
+messageEntityTextUrl#76a6d327 offset:int length:int url:string = MessageEntity;
+messageEntityMentionName#352dca58 offset:int length:int user_id:int = MessageEntity;
+messageEntityPhone#9b69e34b offset:int length:int = MessageEntity;
+messageEntityCashtag#4c4e743f offset:int length:int = MessageEntity;
+inputStickerSetShortName#861cc8a0 short_name:string = InputStickerSet;
+inputStickerSetEmpty#ffb62b95 = InputStickerSet;
+decryptedMessageMediaVenue#8a0df56f lat:double long:double title:string address:string provider:string venue_id:string = DecryptedMessageMedia;
+decryptedMessageMediaWebPage#e50511d8 url:string = DecryptedMessageMedia;
+
+// layer 66
+
+sendMessageRecordRoundAction#88f27fbc = SendMessageAction;
+sendMessageUploadRoundAction#bb718624 = SendMessageAction;
+documentAttributeVideo66#ef02ce6 flags:# round_message:flags.0?true duration:int w:int h:int = DocumentAttribute;
+
+// layer 73
+
+decryptedMessage#91cc4674 flags:# random_id:long ttl:int message:string media:flags.9?DecryptedMessageMedia entities:flags.7?Vector<MessageEntity> via_bot_name:flags.11?string reply_to_random_id:flags.3?long grouped_id:flags.17?long = DecryptedMessage;
+
+---functions---
+
+test.dummyFunction = Bool;
diff --git a/libs/tdlib/td/td/generate/scheme/secret_api.tlo b/libs/tdlib/td/td/generate/scheme/secret_api.tlo
new file mode 100644
index 0000000000..d6be21615f
--- /dev/null
+++ b/libs/tdlib/td/td/generate/scheme/secret_api.tlo
diff --git a/libs/tdlib/td/td/generate/scheme/td_api.tl b/libs/tdlib/td/td/generate/scheme/td_api.tl
new file mode 100644
index 0000000000..2e7008e47f
--- /dev/null
+++ b/libs/tdlib/td/td/generate/scheme/td_api.tl
@@ -0,0 +1,2885 @@
+double ? = Double;
+string ? = String;
+
+int32 = Int32;
+int53 = Int53;
+int64 = Int64;
+bytes = Bytes;
+
+boolFalse = Bool;
+boolTrue = Bool;
+
+vector {t:Type} # [ t ] = Vector t;
+
+
+//@description An object of this type can be returned on every function call, in case of an error
+//@code Error code; subject to future changes. If the error code is 406, the error message must not be processed in any way and must not be displayed to the user
+//@message Error message; subject to future changes
+error code:int32 message:string = Error;
+
+
+//@description An object of this type is returned on a successful function call for certain functions
+ok = Ok;
+
+
+//@description Contains parameters for TDLib initialization
+//@use_test_dc If set to true, the Telegram test environment will be used instead of the production environment
+//@database_directory The path to the directory for the persistent database; if empty, the current working directory will be used
+//@files_directory The path to the directory for storing files; if empty, database_directory will be used
+//@use_file_database If set to true, information about downloaded and uploaded files will be saved between application restarts
+//@use_chat_info_database If set to true, the library will maintain a cache of users, basic groups, supergroups, channels and secret chats. Implies use_file_database
+//@use_message_database If set to true, the library will maintain a cache of chats and messages. Implies use_chat_info_database
+//@use_secret_chats If set to true, support for secret chats will be enabled
+//@api_id Application identifier for Telegram API access, which can be obtained at https://my.telegram.org
+//@api_hash Application identifier hash for Telegram API access, which can be obtained at https://my.telegram.org
+//@system_language_code IETF language tag of the user's operating system language; must be non-empty
+//@device_model Model of the device the application is being run on; must be non-empty
+//@system_version Version of the operating system the application is being run on; must be non-empty
+//@application_version Application version; must be non-empty
+//@enable_storage_optimizer If set to true, old files will automatically be deleted
+//@ignore_file_names If set to true, original file names will be ignored. Otherwise, downloaded files will be saved under names as close as possible to the original name
+tdlibParameters use_test_dc:Bool database_directory:string files_directory:string use_file_database:Bool use_chat_info_database:Bool use_message_database:Bool use_secret_chats:Bool api_id:int32 api_hash:string system_language_code:string device_model:string system_version:string application_version:string enable_storage_optimizer:Bool ignore_file_names:Bool = TdlibParameters;
+
+
+//@class AuthenticationCodeType @description Provides information about the method by which an authentication code is delivered to the user
+
+//@description An authentication code is delivered via a private Telegram message, which can be viewed in another client @length Length of the code
+authenticationCodeTypeTelegramMessage length:int32 = AuthenticationCodeType;
+
+//@description An authentication code is delivered via an SMS message to the specified phone number @length Length of the code
+authenticationCodeTypeSms length:int32 = AuthenticationCodeType;
+
+//@description An authentication code is delivered via a phone call to the specified phone number @length Length of the code
+authenticationCodeTypeCall length:int32 = AuthenticationCodeType;
+
+//@description An authentication code is delivered by an immediately cancelled call to the specified phone number. The number from which the call was made is the code @pattern Pattern of the phone number from which the call will be made
+authenticationCodeTypeFlashCall pattern:string = AuthenticationCodeType;
+
+
+//@description Information about the authentication code that was sent @phone_number A phone number that is being authenticated @type Describes the way the code was sent to the user @next_type Describes the way the next code will be sent to the user; may be null @timeout Timeout before the code should be re-sent, in seconds
+authenticationCodeInfo phone_number:string type:AuthenticationCodeType next_type:AuthenticationCodeType timeout:int32 = AuthenticationCodeInfo;
+
+
+//@class AuthorizationState @description Represents the current authorization state of the client
+
+//@description TDLib needs TdlibParameters for initialization
+authorizationStateWaitTdlibParameters = AuthorizationState;
+
+//@description TDLib needs an encryption key to decrypt the local database @is_encrypted True, if the database is currently encrypted
+authorizationStateWaitEncryptionKey is_encrypted:Bool = AuthorizationState;
+
+//@description TDLib needs the user's phone number to authorize
+authorizationStateWaitPhoneNumber = AuthorizationState;
+
+//@description TDLib needs the user's authentication code to finalize authorization @is_registered True, if the user is already registered @code_info Information about the authorization code that was sent
+authorizationStateWaitCode is_registered:Bool code_info:authenticationCodeInfo = AuthorizationState;
+
+//@description The user has been authorized, but needs to enter a password to start using the application @password_hint Hint for the password; can be empty @has_recovery_email_address True if a recovery email address has been set up
+//@recovery_email_address_pattern Pattern of the email address to which the recovery email was sent; empty until a recovery email has been sent
+authorizationStateWaitPassword password_hint:string has_recovery_email_address:Bool recovery_email_address_pattern:string = AuthorizationState;
+
+//@description The user has been successfully authorized. TDLib is now ready to answer queries
+authorizationStateReady = AuthorizationState;
+
+//@description The user is currently logging out
+authorizationStateLoggingOut = AuthorizationState;
+
+//@description TDLib is closing, all subsequent queries will be answered with the error 500. Note that closing TDLib can take a while. All resources will be freed only after authorizationStateClosed has been received
+authorizationStateClosing = AuthorizationState;
+
+//@description TDLib client is in its final state. All databases are closed and all resources are released. No other updates will be received after this. All queries will be responded to
+//-with error code 500. To continue working, one should create a new instance of the TDLib client
+authorizationStateClosed = AuthorizationState;
+
+
+//@description Represents the current state of 2-step verification @has_password True if a 2-step verification password has been set up @password_hint Hint for the password; can be empty @has_recovery_email_address True if a recovery email has been set up @unconfirmed_recovery_email_address_pattern Pattern of the email address to which a confirmation email was sent
+passwordState has_password:Bool password_hint:string has_recovery_email_address:Bool unconfirmed_recovery_email_address_pattern:string = PasswordState;
+
+//@description Contains information available to the user after requesting password recovery @recovery_email_address_pattern Pattern of the email address to which a recovery email was sent
+passwordRecoveryInfo recovery_email_address_pattern:string = PasswordRecoveryInfo;
+
+//@description Contains information about the current recovery email address @recovery_email_address Recovery email address
+recoveryEmailAddress recovery_email_address:string = RecoveryEmailAddress;
+
+
+//@description Returns information about the availability of a temporary password, which can be used for payments @has_password True, if a temporary password is available @valid_for Time left before the temporary password expires, in seconds
+temporaryPasswordState has_password:Bool valid_for:int32 = TemporaryPasswordState;
+
+
+//@description Represents a local file
+//@path Local path to the locally available file part; may be empty
+//@can_be_downloaded True, if it is possible to try to download or generate the file
+//@can_be_deleted True, if the file can be deleted
+//@is_downloading_active True, if the file is currently being downloaded (or a local copy is being generated by some other means)
+//@is_downloading_completed True, if the local copy is fully available
+//@downloaded_prefix_size If is_downloading_completed is false, then only some prefix of the file is ready to be read. downloaded_prefix_size is the size of that prefix
+//@downloaded_size Total downloaded file bytes. Should be used only for calculating download progress. The actual file size may be bigger, and some parts of it may contain garbage
+localFile path:string can_be_downloaded:Bool can_be_deleted:Bool is_downloading_active:Bool is_downloading_completed:Bool downloaded_prefix_size:int32 downloaded_size:int32 = LocalFile;
+
+//@description Represents a remote file
+//@id Remote file identifier, may be empty. Can be used across application restarts or even from other devices for the current user. If the ID starts with "http://" or "https://", it represents the HTTP URL of the file. TDLib is currently unable to download files if only their URL is known.
+//-If downloadFile is called on such a file or if it is sent to a secret chat, TDLib starts a file generation process by sending updateFileGenerationStart to the client with the HTTP URL in the original_path and "#url#" as the conversion string. Clients should generate the file by downloading it to the specified location
+//@is_uploading_active True, if the file is currently being uploaded (or a remote copy is being generated by some other means)
+//@is_uploading_completed True, if a remote copy is fully available
+//@uploaded_size Size of the remote available part of the file; 0 if unknown
+remoteFile id:string is_uploading_active:Bool is_uploading_completed:Bool uploaded_size:int32 = RemoteFile;
+
+//@description Represents a file
+//@id Unique file identifier
+//@size File size; 0 if unknown
+//@expected_size Expected file size in case the exact file size is unknown, but an approximate size is known. Can be used to show download/upload progress
+//@local Information about the local copy of the file
+//@remote Information about the remote copy of the file
+file id:int32 size:int32 expected_size:int32 local:localFile remote:remoteFile = File;
+
+
+//@class InputFile @description Points to a file
+
+//@description A file defined by its unique ID @id Unique file identifier
+inputFileId id:int32 = InputFile;
+
+//@description A file defined by its remote ID @id Remote file identifier
+inputFileRemote id:string = InputFile;
+
+//@description A file defined by a local path @path Local path to the file
+inputFileLocal path:string = InputFile;
+
+//@description A file generated by the client @original_path Local path to a file from which the file is generated, may be empty if there is no such file @conversion String specifying the conversion applied to the original file; should be persistent across application restarts @expected_size Expected size of the generated file; 0 if unknown
+inputFileGenerated original_path:string conversion:string expected_size:int32 = InputFile;
+
+
+//@description Photo description @type Thumbnail type (see https://core.telegram.org/constructor/photoSize) @photo Information about the photo file @width Photo width @height Photo height
+photoSize type:string photo:file width:int32 height:int32 = PhotoSize;
+
+
+//@class MaskPoint @description Part of the face, relative to which a mask should be placed
+
+//@description A mask should be placed relatively to the forehead
+maskPointForehead = MaskPoint;
+
+//@description A mask should be placed relatively to the eyes
+maskPointEyes = MaskPoint;
+
+//@description A mask should be placed relatively to the mouth
+maskPointMouth = MaskPoint;
+
+//@description A mask should be placed relatively to the chin
+maskPointChin = MaskPoint;
+
+//@description Position on a photo where a mask should be placed @point Part of the face, relative to which the mask should be placed
+//@x_shift Shift by X-axis measured in widths of the mask scaled to the face size, from left to right. (For example, -1.0 will place the mask just to the left of the default mask position)
+//@y_shift Shift by Y-axis measured in heights of the mask scaled to the face size, from top to bottom. (For example, 1.0 will place the mask just below the default mask position)
+//@scale Mask scaling coefficient. (For example, 2.0 means a doubled size)
+maskPosition point:MaskPoint x_shift:double y_shift:double scale:double = MaskPosition;
+
+
+//@description Represents a part of the text that needs to be formatted in some unusual way @offset Offset of the entity in UTF-16 code points @length Length of the entity, in UTF-16 code points @type Type of the entity
+textEntity offset:int32 length:int32 type:TextEntityType = TextEntity;
+
+//@description Contains a list of text entities @entities List of text entities
+textEntities entities:vector<textEntity> = TextEntities;
+
+//@description A text with some entities @text The text @entities Entities contained in the text
+formattedText text:string entities:vector<textEntity> = FormattedText;
+
+
+//@description Describes an animation file. The animation must be encoded in GIF or MPEG4 format @duration Duration of the animation, in seconds; as defined by the sender @width Width of the animation @height Height of the animation
+//@file_name Original name of the file; as defined by the sender @mime_type MIME type of the file, usually "image/gif" or "video/mp4" @thumbnail Animation thumbnail; may be null @animation File containing the animation
+animation duration:int32 width:int32 height:int32 file_name:string mime_type:string thumbnail:photoSize animation:file = Animation;
+
+//@description Describes an audio file. Audio is usually in MP3 format @duration Duration of the audio, in seconds; as defined by the sender @title Title of the audio; as defined by the sender @performer Performer of the audio; as defined by the sender
+//@file_name Original name of the file; as defined by the sender @mime_type The MIME type of the file; as defined by the sender @album_cover_thumbnail The thumbnail of the album cover; as defined by the sender. The full size thumbnail should be extracted from the downloaded file; may be null @audio File containing the audio
+audio duration:int32 title:string performer:string file_name:string mime_type:string album_cover_thumbnail:photoSize audio:file = Audio;
+
+//@description Describes a document of any type @file_name Original name of the file; as defined by the sender @mime_type MIME type of the file; as defined by the sender
+//@thumbnail Document thumbnail; as defined by the sender; may be null @document File containing the document
+document file_name:string mime_type:string thumbnail:photoSize document:file = Document;
+
+//@description Describes a photo @id Photo identifier; 0 for deleted photos @has_stickers True, if stickers were added to the photo @sizes Available variants of the photo, in different sizes
+photo id:int64 has_stickers:Bool sizes:vector<photoSize> = Photo;
+
+//@description Describes a sticker @set_id The identifier of the sticker set to which the sticker belongs; 0 if none @width Sticker width; as defined by the sender @height Sticker height; as defined by the sender
+//@emoji Emoji corresponding to the sticker @is_mask True, if the sticker is a mask @mask_position Position where the mask should be placed; may be null @thumbnail Sticker thumbnail in WEBP or JPEG format; may be null @sticker File containing the sticker
+sticker set_id:int64 width:int32 height:int32 emoji:string is_mask:Bool mask_position:maskPosition thumbnail:photoSize sticker:file = Sticker;
+
+//@description Describes a video file @duration Duration of the video, in seconds; as defined by the sender @width Video width; as defined by the sender @height Video height; as defined by the sender
+//@file_name Original name of the file; as defined by the sender @mime_type MIME type of the file; as defined by the sender @has_stickers True, if stickers were added to the photo
+//@supports_streaming True, if the video should be tried to be streamed @thumbnail Video thumbnail; as defined by the sender; may be null @video File containing the video
+video duration:int32 width:int32 height:int32 file_name:string mime_type:string has_stickers:Bool supports_streaming:Bool thumbnail:photoSize video:file = Video;
+
+//@description Describes a video note. The video must be equal in width and height, cropped to a circle, and stored in MPEG4 format @duration Duration of the video, in seconds; as defined by the sender @length Video width and height; as defined by the sender @thumbnail Video thumbnail; as defined by the sender; may be null @video File containing the video
+videoNote duration:int32 length:int32 thumbnail:photoSize video:file = VideoNote;
+
+//@description Describes a voice note. The voice note must be encoded with the Opus codec, and stored inside an OGG container. Voice notes can have only a single audio channel @duration Duration of the voice note, in seconds; as defined by the sender
+//@waveform A waveform representation of the voice note in 5-bit format @mime_type MIME type of the file; as defined by the sender @voice File containing the voice note
+voiceNote duration:int32 waveform:bytes mime_type:string voice:file = VoiceNote;
+
+//@description Describes a user contact @phone_number Phone number of the user @first_name First name of the user; 1-255 characters in length @last_name Last name of the user @user_id Identifier of the user, if known; otherwise 0
+contact phone_number:string first_name:string last_name:string user_id:int32 = Contact;
+
+//@description Describes a location on planet Earth @latitude Latitude of the location in degrees; as defined by the sender @longitude Longitude of the location, in degrees; as defined by the sender
+location latitude:double longitude:double = Location;
+
+//@description Describes a venue @location Venue location; as defined by the sender @title Venue name; as defined by the sender @address Venue address; as defined by the sender @provider Provider of the venue database; as defined by the sender. Currently only "foursquare" needs to be supported
+//@id Identifier of the venue in the provider database; as defined by the sender
+venue location:location title:string address:string provider:string id:string = Venue;
+
+//@description Describes a game @id Game ID @short_name Game short name. To share a game use the URL https://t.me/{bot_username}?game={game_short_name} @title Game title @text Game text, usually containing scoreboards for a game
+//@param_description Game description @photo Game photo @animation Game animation; may be null
+game id:int64 short_name:string title:string text:formattedText description:string photo:photo animation:animation = Game;
+
+
+//@description Describes a user profile photo @id Photo identifier; 0 for an empty photo. Can be used to find a photo in a list of userProfilePhotos
+//@small A small (160x160) user profile photo @big A big (640x640) user profile photo
+profilePhoto id:int64 small:file big:file = ProfilePhoto;
+
+//@description Describes the photo of a chat @small A small (160x160) chat photo @big A big (640x640) chat photo
+chatPhoto small:file big:file = ChatPhoto;
+
+
+//@class LinkState @description Represents the relationship between user A and user B. For incoming_link, user A is the current user; for outgoing_link, user B is the current user
+
+//@description The phone number of user A is not known to user B
+linkStateNone = LinkState;
+
+//@description The phone number of user A is known but that number has not been saved to the contacts list of user B
+linkStateKnowsPhoneNumber = LinkState;
+
+//@description The phone number of user A has been saved to the contacts list of user B
+linkStateIsContact = LinkState;
+
+
+//@class UserType @description Represents the type of the user. The following types are possible: regular users, deleted users and bots
+
+//@description A regular user
+userTypeRegular = UserType;
+
+//@description A deleted user or deleted bot. No information on the user besides the user_id is available. It is not possible to perform any active actions on this type of user
+userTypeDeleted = UserType;
+
+//@description A bot (see https://core.telegram.org/bots) @can_join_groups True, if the bot can be invited to basic group and supergroup chats
+//@can_read_all_group_messages True, if the bot can read all messages in basic group or supergroup chats and not just those addressed to the bot. In private and channel chats a bot can always read all messages
+//@is_inline True, if the bot supports inline queries @inline_query_placeholder Placeholder for inline queries (displayed on the client input field) @need_location True, if the location of the user should be sent with every inline query to this bot
+userTypeBot can_join_groups:Bool can_read_all_group_messages:Bool is_inline:Bool inline_query_placeholder:string need_location:Bool = UserType;
+
+//@description No information on the user besides the user_id is available, yet this user has not been deleted. This object is extremely rare and must be handled like a deleted user. It is not possible to perform any actions on users of this type
+userTypeUnknown = UserType;
+
+
+//@description Represents commands supported by a bot @command Text of the bot command @param_description Description of the bot command
+botCommand command:string description:string = BotCommand;
+
+//@description Provides information about a bot and its supported commands @param_description Long description shown on the user info page @commands A list of commands supported by the bot
+botInfo description:string commands:vector<botCommand> = BotInfo;
+
+
+//@description Represents a user @id User identifier @first_name First name of the user @last_name Last name of the user @username Username of the user
+//@phone_number Phone number of the user @status Current online status of the user @profile_photo Profile photo of the user; may be null
+//@outgoing_link Relationship from the current user to the other user @incoming_link Relationship from the other user to the current user @is_verified True, if the user is verified @restriction_reason If non-empty, it contains the reason why access to this user must be restricted. The format of the string is "{type}: {description}".
+//-{type} contains the type of the restriction and at least one of the suffixes "-all", "-ios", "-android", or "-wp", which describe the platforms on which access should be restricted. (For example, "terms-ios-android". {description} contains a human-readable description of the restriction, which can be shown to the user)
+//@have_access If false, the user is inaccessible, and the only information known about the user is inside this class. It can't be passed to any method except GetUser @type Type of the user @language_code IETF language tag of the user's language; only available to bots
+user id:int32 first_name:string last_name:string username:string phone_number:string status:UserStatus profile_photo:profilePhoto outgoing_link:LinkState incoming_link:LinkState is_verified:Bool restriction_reason:string have_access:Bool type:UserType language_code:string = User;
+
+//@description Contains full information about a user (except the full list of profile photos) @is_blocked True, if the user is blacklisted by the current user @can_be_called True, if the user can be called @has_private_calls True, if the user can't be called due to their privacy settings
+//@bio A short user bio @share_text For bots, the text that is included with the link when users share the bot @group_in_common_count Number of group chats where both the other user and the current user are a member; 0 for the current user @bot_info If the user is a bot, information about the bot; may be null
+userFullInfo is_blocked:Bool can_be_called:Bool has_private_calls:Bool bio:string share_text:string group_in_common_count:int32 bot_info:botInfo = UserFullInfo;
+
+//@description Contains part of the list of user photos @total_count Total number of user profile photos @photos A list of photos
+userProfilePhotos total_count:int32 photos:vector<photo> = UserProfilePhotos;
+
+//@description Represents a list of users @total_count Approximate total count of users found @user_ids A list of user identifiers
+users total_count:int32 user_ids:vector<int32> = Users;
+
+
+//@class ChatMemberStatus @description Provides information about the status of a member in a chat
+
+//@description The user is the creator of a chat and has all the administrator privileges @is_member True, if the user is a member of the chat
+chatMemberStatusCreator is_member:Bool = ChatMemberStatus;
+
+//@description The user is a member of a chat and has some additional privileges. In basic groups, administrators can edit and delete messages sent by others, add new members, and ban unprivileged members. In supergroups and channels, there are more detailed options for administrator privileges
+//@can_be_edited True, if the current user can edit the administrator privileges for the called user
+//@can_change_info True, if the administrator can change the chat title, photo, and other settings
+//@can_post_messages True, if the administrator can create channel posts; applicable to channels only
+//@can_edit_messages True, if the administrator can edit messages of other users and pin messages; applicable to channels only
+//@can_delete_messages True, if the administrator can delete messages of other users
+//@can_invite_users True, if the administrator can invite new users to the chat
+//@can_restrict_members True, if the administrator can restrict, ban, or unban chat members
+//@can_pin_messages True, if the administrator can pin messages; applicable to supergroups only
+//@can_promote_members True, if the administrator can add new administrators with a subset of his own privileges or demote administrators that were directly or indirectly promoted by him
+chatMemberStatusAdministrator can_be_edited:Bool can_change_info:Bool can_post_messages:Bool can_edit_messages:Bool can_delete_messages:Bool can_invite_users:Bool can_restrict_members:Bool can_pin_messages:Bool can_promote_members:Bool = ChatMemberStatus;
+
+//@description The user is a member of a chat, without any additional privileges or restrictions
+chatMemberStatusMember = ChatMemberStatus;
+
+//@description The user is under certain restrictions in the chat. Not supported in basic groups and channels
+//@is_member True, if the user is a member of the chat
+//@restricted_until_date Point in time (Unix timestamp) when restrictions will be lifted from the user; 0 if never. If the user is restricted for more than 366 days or for less than 30 seconds from the current time, the user is considered to be restricted forever
+//@can_send_messages True, if the user can send text messages, contacts, locations, and venues
+//@can_send_media_messages True, if the user can send audio files, documents, photos, videos, video notes, and voice notes. Implies can_send_messages permissions
+//@can_send_other_messages True, if the user can send animations, games, and stickers and use inline bots. Implies can_send_media_messages permissions
+//@can_add_web_page_previews True, if the user may add a web page preview to his messages. Implies can_send_messages permissions
+chatMemberStatusRestricted is_member:Bool restricted_until_date:int32 can_send_messages:Bool can_send_media_messages:Bool can_send_other_messages:Bool can_add_web_page_previews:Bool = ChatMemberStatus;
+
+//@description The user is not a chat member
+chatMemberStatusLeft = ChatMemberStatus;
+
+//@description The user was banned (and hence is not a member of the chat). Implies the user can't return to the chat or view messages
+//@banned_until_date Point in time (Unix timestamp) when the user will be unbanned; 0 if never. If the user is banned for more than 366 days or for less than 30 seconds from the current time, the user is considered to be banned forever
+chatMemberStatusBanned banned_until_date:int32 = ChatMemberStatus;
+
+
+//@description A user with information about joining/leaving a chat @user_id User identifier of the chat member @inviter_user_id Identifier of a user that invited/promoted/banned this member in the chat; 0 if unknown
+//@joined_chat_date Point in time (Unix timestamp) when the user joined a chat @status Status of the member in the chat @bot_info If the user is a bot, information about the bot; may be null. Can be null even for a bot if the bot is not a chat member
+chatMember user_id:int32 inviter_user_id:int32 joined_chat_date:int32 status:ChatMemberStatus bot_info:botInfo = ChatMember;
+
+//@description Contains a list of chat members @total_count Approximate total count of chat members found @members A list of chat members
+chatMembers total_count:int32 members:vector<chatMember> = ChatMembers;
+
+
+//@class SupergroupMembersFilter @description Specifies the kind of chat members to return in getSupergroupMembers
+
+//@description Returns recently active users in reverse chronological order
+supergroupMembersFilterRecent = SupergroupMembersFilter;
+
+//@description Returns the creator and administrators
+supergroupMembersFilterAdministrators = SupergroupMembersFilter;
+
+//@description Used to search for supergroup or channel members via a (string) query @query Query to search for
+supergroupMembersFilterSearch query:string = SupergroupMembersFilter;
+
+//@description Returns restricted supergroup members; can be used only by administrators @query Query to search for
+supergroupMembersFilterRestricted query:string = SupergroupMembersFilter;
+
+//@description Returns users banned from the supergroup or channel; can be used only by administrators @query Query to search for
+supergroupMembersFilterBanned query:string = SupergroupMembersFilter;
+
+//@description Returns bot members of the supergroup or channel
+supergroupMembersFilterBots = SupergroupMembersFilter;
+
+
+//@description Represents a basic group of 0-200 users (must be upgraded to a supergroup to accommodate more than 200 users)
+//@id Group identifier
+//@member_count Number of members in the group
+//@status Status of the current user in the group
+//@everyone_is_administrator True, if all members have been granted administrator rights in the group
+//@is_active True, if the group is active
+//@upgraded_to_supergroup_id Identifier of the supergroup to which this group was upgraded; 0 if none
+basicGroup id:int32 member_count:int32 status:ChatMemberStatus everyone_is_administrator:Bool is_active:Bool upgraded_to_supergroup_id:int32 = BasicGroup;
+
+//@description Contains full information about a basic group @creator_user_id User identifier of the creator of the group; 0 if unknown @members Group members @invite_link Invite link for this group; available only for the group creator and only after it has been generated at least once
+basicGroupFullInfo creator_user_id:int32 members:vector<chatMember> invite_link:string = BasicGroupFullInfo;
+
+
+//@description Represents a supergroup or channel with zero or more members (subscribers in the case of channels). From the point of view of the system, a channel is a special kind of a supergroup: only administrators can post and see the list of members, and posts from all administrators use the name and photo of the channel instead of individual names and profile photos. Unlike supergroups, channels can have an unlimited number of subscribers
+//@id Supergroup or channel identifier
+//@username Username of the supergroup or channel; empty for private supergroups or channels
+//@date Point in time (Unix timestamp) when the current user joined, or the point in time when the supergroup or channel was created, in case the user is not a member
+//@status Status of the current user in the supergroup or channel
+//@member_count Member count; 0 if unknown. Currently it is guaranteed to be known only if the supergroup or channel was found through SearchPublicChats
+//@anyone_can_invite True, if any member of the supergroup can invite other members. This field has no meaning for channels
+//@sign_messages True, if messages sent to the channel should contain information about the sender. This field is only applicable to channels
+//@is_channel True, if the supergroup is a channel
+//@is_verified True, if the supergroup or channel is verified
+//@restriction_reason If non-empty, contains the reason why access to this supergroup or channel must be restricted. Format of the string is "{type}: {description}".
+//-{type} Contains the type of the restriction and at least one of the suffixes "-all", "-ios", "-android", or "-wp", which describe the platforms on which access should be restricted. (For example, "terms-ios-android". {description} contains a human-readable description of the restriction, which can be shown to the user)
+supergroup id:int32 username:string date:int32 status:ChatMemberStatus member_count:int32 anyone_can_invite:Bool sign_messages:Bool is_channel:Bool is_verified:Bool restriction_reason:string = Supergroup;
+
+//@description Contains full information about a supergroup or channel
+//@param_description Supergroup or channel description
+//@member_count Number of members in the supergroup or channel; 0 if unknown
+//@administrator_count Number of privileged users in the supergroup or channel; 0 if unknown
+//@restricted_count Number of restricted users in the supergroup; 0 if unknown
+//@banned_count Number of users banned from chat; 0 if unknown
+//@can_get_members True, if members of the chat can be retrieved
+//@can_set_username True, if the chat can be made public
+//@can_set_sticker_set True, if the supergroup sticker set can be changed
+//@is_all_history_available True, if new chat members will have access to old messages. In public supergroups and both public and private channels, old messages are always available, so this option affects only private supergroups. The value of this field is only available for chat administrators
+//@sticker_set_id Identifier of the supergroup sticker set; 0 if none
+//@invite_link Invite link for this chat
+//@pinned_message_id Identifier of the pinned message in the chat; 0 if none
+//@upgraded_from_basic_group_id Identifier of the basic group from which supergroup was upgraded; 0 if none
+//@upgraded_from_max_message_id Identifier of the last message in the basic group from which supergroup was upgraded; 0 if none
+supergroupFullInfo description:string member_count:int32 administrator_count:int32 restricted_count:int32 banned_count:int32 can_get_members:Bool can_set_username:Bool can_set_sticker_set:Bool is_all_history_available:Bool sticker_set_id:int64 invite_link:string pinned_message_id:int53 upgraded_from_basic_group_id:int32 upgraded_from_max_message_id:int53 = SupergroupFullInfo;
+
+
+//@class SecretChatState @description Describes the current secret chat state
+
+//@description The secret chat is not yet created; waiting for the other user to get online
+secretChatStatePending = SecretChatState;
+
+//@description The secret chat is ready to use
+secretChatStateReady = SecretChatState;
+
+//@description The secret chat is closed
+secretChatStateClosed = SecretChatState;
+
+
+//@description Represents a secret chat
+//@id Secret chat identifier
+//@user_id Identifier of the chat partner
+//@state State of the secret chat
+//@is_outbound True, if the chat was created by the current user; otherwise false
+//@ttl Current message Time To Live setting (self-destruct timer) for the chat, in seconds
+//@key_hash Hash of the currently used key for comparison with the hash of the chat partner's key. This is a string of 36 bytes, which must be used to make a 12x12 square image with a color depth of 4. The first 16 bytes should be used to make a central 8x8 square, while the remaining 20 bytes should be used to construct a 2-pixel-wide border around that square.
+//-Alternatively, the first 32 bytes of the hash can be converted to the hexadecimal format and printed as 32 2-digit hex numbers
+//@layer Secret chat layer; determines features supported by the other client. Video notes are supported if the layer >= 66
+secretChat id:int32 user_id:int32 state:SecretChatState is_outbound:Bool ttl:int32 key_hash:bytes layer:int32 = SecretChat;
+
+
+//@class MessageForwardInfo @description Contains information about the initial sender of a forwarded message
+
+//@description The message was originally written by a known user @sender_user_id Identifier of the user that originally sent this message @date Point in time (Unix timestamp) when the message was originally sent
+//@forwarded_from_chat_id For messages forwarded to the chat with the current user (saved messages), the identifier of the chat from which the message was forwarded; 0 if unknown
+//@forwarded_from_message_id For messages forwarded to the chat with the current user (saved messages) the identifier of the original message from which the new message was forwarded; 0 if unknown
+messageForwardedFromUser sender_user_id:int32 date:int32 forwarded_from_chat_id:int53 forwarded_from_message_id:int53 = MessageForwardInfo;
+
+//@description The message was originally a post in a channel @chat_id Identifier of the chat from which the message was forwarded @author_signature Post author signature
+//@date Point in time (Unix timestamp) when the message was originally sent @message_id Message identifier of the original message from which the new message was forwarded; 0 if unknown
+//@forwarded_from_chat_id For messages forwarded to the chat with the current user (saved messages), the identifier of the chat from which the message was forwarded; 0 if unknown
+//@forwarded_from_message_id For messages forwarded to the chat with the current user (saved messages), the identifier of the original message from which the new message was forwarded; 0 if unknown
+messageForwardedPost chat_id:int53 author_signature:string date:int32 message_id:int53 forwarded_from_chat_id:int53 forwarded_from_message_id:int53 = MessageForwardInfo;
+
+
+//@class MessageSendingState @description Contains information about the sending state of the message
+
+//@description The message is being sent now, but has not yet been delivered to the server
+messageSendingStatePending = MessageSendingState;
+
+//@description The message failed to be sent
+messageSendingStateFailed = MessageSendingState;
+
+
+//@description Describes a message
+//@id Unique message identifier
+//@sender_user_id Identifier of the user who sent the message; 0 if unknown. It is unknown for channel posts
+//@chat_id Chat identifier
+//@sending_state Information about the sending state of the message; may be null
+//@is_outgoing True, if the message is outgoing
+//@can_be_edited True, if the message can be edited
+//@can_be_forwarded True, if the message can be forwarded
+//@can_be_deleted_only_for_self True, if the message can be deleted only for the current user while other users will continue to see it
+//@can_be_deleted_for_all_users True, if the message can be deleted for all users
+//@is_channel_post True, if the message is a channel post. All messages to channels are channel posts, all other messages are not channel posts
+//@contains_unread_mention True, if the message contains an unread mention for the current user
+//@date Point in time (Unix timestamp) when the message was sent
+//@edit_date Point in time (Unix timestamp) when the message was last edited
+//@forward_info Information about the initial message sender; may be null
+//@reply_to_message_id If non-zero, the identifier of the message this message is replying to; can be the identifier of a deleted message
+//@ttl For self-destructing messages, the message's TTL (Time To Live), in seconds; 0 if none. TDLib will send updateDeleteMessages or updateMessageContent once the TTL expires
+//@ttl_expires_in Time left before the message expires, in seconds
+//@via_bot_user_id If non-zero, the user identifier of the bot through which this message was sent
+//@author_signature For channel posts, optional author signature
+//@views Number of times this message was viewed
+//@media_album_id Unique identifier of an album this message belongs to. Only photos and videos can be grouped together in albums
+//@content Content of the message
+//@reply_markup Reply markup for the message; may be null
+message id:int53 sender_user_id:int32 chat_id:int53 sending_state:MessageSendingState is_outgoing:Bool can_be_edited:Bool can_be_forwarded:Bool can_be_deleted_only_for_self:Bool can_be_deleted_for_all_users:Bool is_channel_post:Bool contains_unread_mention:Bool date:int32 edit_date:int32 forward_info:MessageForwardInfo reply_to_message_id:int53 ttl:int32 ttl_expires_in:double via_bot_user_id:int32 author_signature:string views:int32 media_album_id:int64 content:MessageContent reply_markup:ReplyMarkup = Message;
+
+//@description Contains a list of messages @total_count Approximate total count of messages found @messages List of messages; messages may be null
+messages total_count:int32 messages:vector<message> = Messages;
+
+//@description Contains a list of messages found by a search @messages List of messages @next_from_search_id Value to pass as from_search_id to get more results
+foundMessages messages:vector<message> next_from_search_id:int64 = FoundMessages;
+
+
+//@class NotificationSettingsScope @description Describes the types of chats for which notification settings are applied
+
+//@description Notification settings applied to a particular chat @chat_id Chat identifier
+notificationSettingsScopeChat chat_id:int53 = NotificationSettingsScope;
+
+//@description Notification settings applied to all private chats
+notificationSettingsScopePrivateChats = NotificationSettingsScope;
+
+//@description Notification settings applied to all basic groups and channels. (Supergroups have no common settings)
+notificationSettingsScopeBasicGroupChats = NotificationSettingsScope;
+
+//@description Notification settings applied to all chats
+notificationSettingsScopeAllChats = NotificationSettingsScope;
+
+
+//@description Contains information about notification settings for a chat or several chats @mute_for Time left before notifications will be unmuted, in seconds @sound An audio file name for notification sounds; only applies to iOS applications @show_preview True, if message content should be displayed in notifications
+notificationSettings mute_for:int32 sound:string show_preview:Bool = NotificationSettings;
+
+
+//@description Contains information about a message draft @reply_to_message_id Identifier of the message to reply to; 0 if none @input_message_text Content of the message draft; this should always be of type inputMessageText
+draftMessage reply_to_message_id:int53 input_message_text:InputMessageContent = DraftMessage;
+
+
+//@class ChatType @description Describes the type of a chat
+
+//@description An ordinary chat with a user @user_id User identifier
+chatTypePrivate user_id:int32 = ChatType;
+
+//@description A basic group (i.e., a chat with 0-200 other users) @basic_group_id Basic group identifier
+chatTypeBasicGroup basic_group_id:int32 = ChatType;
+
+//@description A supergroup (i.e. a chat with up to GetOption("supergroup_max_size") other users), or channel (with unlimited members) @supergroup_id Supergroup or channel identifier @is_channel True, if the supergroup is a channel
+chatTypeSupergroup supergroup_id:int32 is_channel:Bool = ChatType;
+
+//@description A secret chat with a user @secret_chat_id Secret chat identifier @user_id User identifier of the secret chat peer
+chatTypeSecret secret_chat_id:int32 user_id:int32 = ChatType;
+
+
+//@description A chat. (Can be a private chat, basic group, supergroup, or secret chat)
+//@id Chat unique identifier
+//@type Type of the chat
+//@title Chat title
+//@photo Chat photo; may be null
+//@last_message Last message in the chat; may be null
+//@order Descending parameter by which chats are sorted in the main chat list. If the order number of two chats is the same, they must be sorted in descending order by ID. If 0, the position of the chat in the list is undetermined
+//@is_pinned True, if the chat is pinned
+//@can_be_reported True, if the chat can be reported to Telegram moderators through reportChat
+//@unread_count Number of unread messages in the chat
+//@last_read_inbox_message_id Identifier of the last read incoming message
+//@last_read_outbox_message_id Identifier of the last read outgoing message
+//@unread_mention_count Number of unread messages with a mention/reply in the chat
+//@notification_settings Notification settings for this chat
+//@reply_markup_message_id Identifier of the message from which reply markup needs to be used; 0 if there is no default custom reply markup in the chat
+//@draft_message A draft of a message in the chat; may be null
+//@client_data Contains client-specific data associated with the chat. (For example, the chat position or local chat notification settings can be stored here.) Persistent if a message database is used
+chat id:int53 type:ChatType title:string photo:chatPhoto last_message:message order:int64 is_pinned:Bool can_be_reported:Bool unread_count:int32 last_read_inbox_message_id:int53 last_read_outbox_message_id:int53 unread_mention_count:int32 notification_settings:notificationSettings reply_markup_message_id:int53 draft_message:draftMessage client_data:string = Chat;
+
+//@description Represents a list of chats @chat_ids List of chat identifiers
+chats chat_ids:vector<int53> = Chats;
+
+
+//@description Contains a chat invite link @invite_link Chat invite link
+chatInviteLink invite_link:string = ChatInviteLink;
+
+//@description Contains information about a chat invite link
+//@chat_id Chat identifier of the invite link; 0 if the user is not a member of this chat
+//@type Contains information about the type of the chat
+//@title Title of the chat
+//@photo Chat photo; may be null
+//@member_count Number of members
+//@member_user_ids User identifiers of some chat members that may be known to the current user
+//@is_public True, if the chat is a public supergroup or channel with a username
+chatInviteLinkInfo chat_id:int53 type:ChatType title:string photo:chatPhoto member_count:int32 member_user_ids:vector<int32> is_public:Bool = ChatInviteLinkInfo;
+
+
+//@class KeyboardButtonType @description Describes a keyboard button type
+
+//@description A simple button, with text that should be sent when the button is pressed
+keyboardButtonTypeText = KeyboardButtonType;
+
+//@description A button that sends the user's phone number when pressed; available only in private chats
+keyboardButtonTypeRequestPhoneNumber = KeyboardButtonType;
+
+//@description A button that sends the user's location when pressed; available only in private chats
+keyboardButtonTypeRequestLocation = KeyboardButtonType;
+
+
+//@description Represents a single button in a bot keyboard @text Text of the button @type Type of the button
+keyboardButton text:string type:KeyboardButtonType = KeyboardButton;
+
+
+//@class InlineKeyboardButtonType @description Describes the type of an inline keyboard button
+
+//@description A button that opens a specified URL @url URL to open
+inlineKeyboardButtonTypeUrl url:string = InlineKeyboardButtonType;
+
+//@description A button that sends a special callback query to a bot @data Data to be sent to the bot via a callback query
+inlineKeyboardButtonTypeCallback data:bytes = InlineKeyboardButtonType;
+
+//@description A button with a game that sends a special callback query to a bot. This button must be in the first column and row of the keyboard and can be attached only to a message with content of the type messageGame
+inlineKeyboardButtonTypeCallbackGame = InlineKeyboardButtonType;
+
+//@description A button that forces an inline query to the bot to be inserted in the input field @query Inline query to be sent to the bot @in_current_chat True, if the inline query should be sent from the current chat
+inlineKeyboardButtonTypeSwitchInline query:string in_current_chat:Bool = InlineKeyboardButtonType;
+
+//@description A button to buy something. This button must be in the first column and row of the keyboard and can be attached only to a message with content of the type messageInvoice
+inlineKeyboardButtonTypeBuy = InlineKeyboardButtonType;
+
+
+//@description Represents a single button in an inline keyboard @text Text of the button @type Type of the button
+inlineKeyboardButton text:string type:InlineKeyboardButtonType = InlineKeyboardButton;
+
+
+//@class ReplyMarkup @description Contains a description of a custom keyboard and actions that can be done with it to quickly reply to bots
+
+//@description Instructs clients to remove the keyboard once this message has been received. This kind of keyboard can't be received in an incoming message; instead, UpdateChatReplyMarkup with message_id == 0 will be sent
+//@is_personal True, if the keyboard is removed only for the mentioned users or the target user of a reply
+replyMarkupRemoveKeyboard is_personal:Bool = ReplyMarkup;
+
+//@description Instructs clients to force a reply to this message
+//@is_personal True, if a forced reply must automatically be shown to the current user. For outgoing messages, specify true to show the forced reply only for the mentioned users and for the target user of a reply
+replyMarkupForceReply is_personal:Bool = ReplyMarkup;
+
+//@description Contains a custom keyboard layout to quickly reply to bots
+//@rows A list of rows of bot keyboard buttons
+//@resize_keyboard True, if the client needs to resize the keyboard vertically
+//@one_time True, if the client needs to hide the keyboard after use
+//@is_personal True, if the keyboard must automatically be shown to the current user. For outgoing messages, specify true to show the keyboard only for the mentioned users and for the target user of a reply
+replyMarkupShowKeyboard rows:vector<vector<keyboardButton>> resize_keyboard:Bool one_time:Bool is_personal:Bool = ReplyMarkup;
+
+//@description Contains an inline keyboard layout
+//@rows A list of rows of inline keyboard buttons
+replyMarkupInlineKeyboard rows:vector<vector<inlineKeyboardButton>> = ReplyMarkup;
+
+
+//@class RichText @description Describes a text object inside an instant-view web page
+
+//@description A plain text @text Text
+richTextPlain text:string = RichText;
+
+//@description A bold rich text @text Text
+richTextBold text:RichText = RichText;
+
+//@description An italicized rich text @text Text
+richTextItalic text:RichText = RichText;
+
+//@description An underlined rich text @text Text
+richTextUnderline text:RichText = RichText;
+
+//@description A strike-through rich text @text Text
+richTextStrikethrough text:RichText = RichText;
+
+//@description A fixed-width rich text @text Text
+richTextFixed text:RichText = RichText;
+
+//@description A rich text URL link @text Text @url URL
+richTextUrl text:RichText url:string = RichText;
+
+//@description A rich text email link @text Text @email_address Email address
+richTextEmailAddress text:RichText email_address:string = RichText;
+
+//@description A concatenation of rich texts @texts Texts
+richTexts texts:vector<RichText> = RichText;
+
+
+//@class PageBlock @description Describes a block of an instant view web page
+
+//@description The title of a page @title Title
+pageBlockTitle title:RichText = PageBlock;
+
+//@description The subtitle of a page @subtitle Subtitle
+pageBlockSubtitle subtitle:RichText = PageBlock;
+
+//@description The author and publishing date of a page @author Author @publish_date Point in time (Unix timestamp) when the article was published; 0 if unknown
+pageBlockAuthorDate author:RichText publish_date:int32 = PageBlock;
+
+//@description A header @header Header
+pageBlockHeader header:RichText = PageBlock;
+
+//@description A subheader @subheader Subheader
+pageBlockSubheader subheader:RichText = PageBlock;
+
+//@description A text paragraph @text Paragraph text
+pageBlockParagraph text:RichText = PageBlock;
+
+//@description A preformatted text paragraph @text Paragraph text @language Programming language for which the text should be formatted
+pageBlockPreformatted text:RichText language:string = PageBlock;
+
+//@description The footer of a page @footer Footer
+pageBlockFooter footer:RichText = PageBlock;
+
+//@description An empty block separating a page
+pageBlockDivider = PageBlock;
+
+//@description An invisible anchor on a page, which can be used in a URL to open the page from the specified anchor @name Name of the anchor
+pageBlockAnchor name:string = PageBlock;
+
+//@description A list of texts @items Texts @is_ordered True, if the items should be marked with numbers
+pageBlockList items:vector<RichText> is_ordered:Bool = PageBlock;
+
+//@description A block quote @text Quote text @caption Quote caption
+pageBlockBlockQuote text:RichText caption:RichText = PageBlock;
+
+//@description A pull quote @text Quote text @caption Quote caption
+pageBlockPullQuote text:RichText caption:RichText = PageBlock;
+
+//@description An animation @animation Animation file; may be null @caption Animation caption @need_autoplay True, if the animation should be played automatically
+pageBlockAnimation animation:animation caption:RichText need_autoplay:Bool = PageBlock;
+
+//@description An audio file @audio Audio file; may be null @caption Audio file caption
+pageBlockAudio audio:audio caption:RichText = PageBlock;
+
+//@description A photo @photo Photo file; may be null @caption Photo caption
+pageBlockPhoto photo:photo caption:RichText = PageBlock;
+
+//@description A video @video Video file; may be null @caption Video caption @need_autoplay True, if the video should be played automatically @is_looped True, if the video should be looped
+pageBlockVideo video:video caption:RichText need_autoplay:Bool is_looped:Bool = PageBlock;
+
+//@description A page cover @cover Cover
+pageBlockCover cover:PageBlock = PageBlock;
+
+//@description An embedded web page @url Web page URL, if available @html HTML-markup of the embedded page @poster_photo Poster photo, if available; may be null @width Block width @height Block height @caption Block caption @is_full_width True, if the block should be full width @allow_scrolling True, if scrolling should be allowed
+pageBlockEmbedded url:string html:string poster_photo:photo width:int32 height:int32 caption:RichText is_full_width:Bool allow_scrolling:Bool = PageBlock;
+
+//@description An embedded post @url Web page URL @author Post author @author_photo Post author photo @date Point in time (Unix timestamp) when the post was created; 0 if unknown @page_blocks Post content @caption Post caption
+pageBlockEmbeddedPost url:string author:string author_photo:photo date:int32 page_blocks:vector<PageBlock> caption:RichText = PageBlock;
+
+//@description A collage @page_blocks Collage item contents @caption Block caption
+pageBlockCollage page_blocks:vector<PageBlock> caption:RichText = PageBlock;
+
+//@description A slideshow @page_blocks Slideshow item contents @caption Block caption
+pageBlockSlideshow page_blocks:vector<PageBlock> caption:RichText = PageBlock;
+
+//@description A link to a chat @title Chat title @photo Chat photo; may be null @username Chat username, by which all other information about the chat should be resolved
+pageBlockChatLink title:string photo:chatPhoto username:string = PageBlock;
+
+
+//@description Describes an instant view page for a web page @page_blocks Content of the web page @is_full True, if the instant view contains the full page. A network request might be needed to get the full web page instant view
+webPageInstantView page_blocks:vector<PageBlock> is_full:Bool = WebPageInstantView;
+
+
+//@description Describes a web page preview @url Original URL of the link @display_url URL to display
+//@type Type of the web page. Can be: article, photo, audio, video, document, profile, app, or something else
+//@site_name Short name of the site (e.g., Google Docs, App Store) @title Title of the content @param_description Description of the content
+//@photo Image representing the content; may be null
+//@embed_url URL to show in the embedded preview
+//@embed_type MIME type of the embedded preview, (e.g., text/html or video/mp4)
+//@embed_width Width of the embedded preview
+//@embed_height Height of the embedded preview
+//@duration Duration of the content, in seconds
+//@author Author of the content
+//@animation Preview of the content as an animation, if available; may be null
+//@audio Preview of the content as an audio file, if available; may be null
+//@document Preview of the content as a document, if available (currently only available for small PDF files and ZIP archives); may be null
+//@sticker Preview of the content as a sticker for small WEBP files, if available; may be null
+//@video Preview of the content as a video, if available; may be null
+//@video_note Preview of the content as a video note, if available; may be null
+//@voice_note Preview of the content as a voice note, if available; may be null
+//@has_instant_view True, if the web page has an instant view
+webPage url:string display_url:string type:string site_name:string title:string description:string photo:photo embed_url:string embed_type:string embed_width:int32 embed_height:int32 duration:int32 author:string animation:animation audio:audio document:document sticker:sticker video:video video_note:videoNote voice_note:voiceNote has_instant_view:Bool = WebPage;
+
+
+//@description Portion of the price of a product (e.g., "delivery cost", "tax amount") @label Label for this portion of the product price @amount Currency amount in minimal quantity of the currency
+labeledPricePart label:string amount:int53 = LabeledPricePart;
+
+//@description Product invoice @currency ISO 4217 currency code @price_parts A list of objects used to calculate the total price of the product @is_test True, if the payment is a test payment
+//@need_name True, if the user's name is needed for payment @need_phone_number True, if the user's phone number is needed for payment @need_email_address True, if the user's email address is needed for payment
+//@need_shipping_address True, if the user's shipping address is needed for payment @send_phone_number_to_provider True, if the user's phone number will be sent to the provider
+//@send_email_address_to_provider True, if the user's email address will be sent to the provider @is_flexible True, if the total price depends on the shipping method
+invoice currency:string price_parts:vector<labeledPricePart> is_test:Bool need_name:Bool need_phone_number:Bool need_email_address:Bool need_shipping_address:Bool send_phone_number_to_provider:Bool send_email_address_to_provider:Bool is_flexible:Bool = Invoice;
+
+//@description Describes a shipping address @country_code Two-letter ISO 3166-1 alpha-2 country code @state State, if applicable @city City @street_line1 First line of the address @street_line2 Second line of the address @postal_code Address postal code
+shippingAddress country_code:string state:string city:string street_line1:string street_line2:string postal_code:string = ShippingAddress;
+
+//@description Order information @name Name of the user @phone_number Phone number of the user @email_address Email address of the user @shipping_address Shipping address for this order; may be null
+orderInfo name:string phone_number:string email_address:string shipping_address:shippingAddress = OrderInfo;
+
+//@description One shipping option @id Shipping option identifier @title Option title @price_parts A list of objects used to calculate the total shipping costs
+shippingOption id:string title:string price_parts:vector<labeledPricePart> = ShippingOption;
+
+//@description Contains information about saved card credentials @id Unique identifier of the saved credentials @title Title of the saved credentials
+savedCredentials id:string title:string = SavedCredentials;
+
+//@class InputCredentials @description Contains information about the payment method chosen by the user
+
+//@description Applies if a user chooses some previously saved payment credentials. To use their previously saved credentials, the user must have a valid temporary password @saved_credentials_id Identifier of the saved credentials
+inputCredentialsSaved saved_credentials_id:string = InputCredentials;
+
+//@description Applies if a user enters new credentials on a payment provider website @data Contains JSON-encoded data with a credential identifier from the payment provider @allow_save True, if the credential identifier can be saved on the server side
+inputCredentialsNew data:string allow_save:Bool = InputCredentials;
+
+//@description Applies if a user enters new credentials using Android Pay @data JSON-encoded data with the credential identifier
+inputCredentialsAndroidPay data:string = InputCredentials;
+
+//@description Applies if a user enters new credentials using Apple Pay @data JSON-encoded data with the credential identifier
+inputCredentialsApplePay data:string = InputCredentials;
+
+//@description Stripe payment provider @publishable_key Stripe API publishable key @need_country True, if the user country must be provided @need_postal_code True, if the user ZIP/postal code must be provided @need_cardholder_name True, if the cardholder name must be provided
+paymentsProviderStripe publishable_key:string need_country:Bool need_postal_code:Bool need_cardholder_name:Bool = PaymentsProviderStripe;
+
+//@description Contains information about an invoice payment form @invoice Full information of the invoice @url Payment form URL @payments_provider Contains information about the payment provider, if available, to support it natively without the need for opening the URL; may be null
+//@saved_order_info Saved server-side order information; may be null @saved_credentials Contains information about saved card credentials; may be null @can_save_credentials True, if the user can choose to save credentials @need_password True, if the user will be able to save credentials protected by a password they set up
+paymentForm invoice:invoice url:string payments_provider:paymentsProviderStripe saved_order_info:orderInfo saved_credentials:savedCredentials can_save_credentials:Bool need_password:Bool = PaymentForm;
+
+//@description Contains a temporary identifier of validated order information, which is stored for one hour. Also contains the available shipping options @order_info_id Temporary identifier of the order information @shipping_options Available shipping options
+validatedOrderInfo order_info_id:string shipping_options:vector<shippingOption> = ValidatedOrderInfo;
+
+//@description Contains the result of a payment request @success True, if the payment request was successful; otherwise the verification_url will be not empty @verification_url URL for additional payment credentials verification
+paymentResult success:Bool verification_url:string = PaymentResult;
+
+//@description Contains information about a successful payment @date Point in time (Unix timestamp) when the payment was made @payments_provider_user_id User identifier of the payment provider bot @invoice Contains information about the invoice
+//@order_info Contains order information; may be null @shipping_option Chosen shipping option; may be null @credentials_title Title of the saved credentials
+paymentReceipt date:int32 payments_provider_user_id:int32 invoice:invoice order_info:orderInfo shipping_option:shippingOption credentials_title:string = PaymentReceipt;
+
+
+//@class MessageContent @description Contains the content of a message
+
+//@description A text message @text Text of the message @web_page A preview of the web page that's mentioned in the text; may be null
+messageText text:formattedText web_page:webPage = MessageContent;
+
+//@description An animation message (GIF-style). @animation Message content @caption Animation caption @is_secret True, if the animation thumbnail must be blurred and the animation must be shown only while tapped
+messageAnimation animation:animation caption:formattedText is_secret:Bool = MessageContent;
+
+//@description An audio message @audio Message content @caption Audio caption
+messageAudio audio:audio caption:formattedText = MessageContent;
+
+//@description A document message (general file) @document Message content @caption Document caption
+messageDocument document:document caption:formattedText = MessageContent;
+
+//@description A photo message @photo Message content @caption Photo caption @is_secret True, if the photo must be blurred and must be shown only while tapped
+messagePhoto photo:photo caption:formattedText is_secret:Bool = MessageContent;
+
+//@description An expired photo message (self-destructed after TTL has elapsed)
+messageExpiredPhoto = MessageContent;
+
+//@description A sticker message @sticker Message content
+messageSticker sticker:sticker = MessageContent;
+
+//@description A video message @video Message content @caption Video caption @is_secret True, if the video thumbnail must be blurred and the video must be shown only while tapped
+messageVideo video:video caption:formattedText is_secret:Bool = MessageContent;
+
+//@description An expired video message (self-destructed after TTL has elapsed)
+messageExpiredVideo = MessageContent;
+
+//@description A video note message @video_note Message content @is_viewed True, if at least one of the recipients has viewed the video note @is_secret True, if the video note thumbnail must be blurred and the video note must be shown only while tapped
+messageVideoNote video_note:videoNote is_viewed:Bool is_secret:Bool = MessageContent;
+
+//@description A voice note message @voice_note Message content @caption Voice note caption @is_listened True, if at least one of the recipients has listened to the voice note
+messageVoiceNote voice_note:voiceNote caption:formattedText is_listened:Bool = MessageContent;
+
+//@description A message with a location @location Message content @live_period Time relative to the message sent date until which the location can be updated, in seconds
+//@expires_in Left time for which the location can be updated, in seconds. updateMessageContent is not sent when this field changes
+messageLocation location:location live_period:int32 expires_in:int32 = MessageContent;
+
+//@description A message with information about a venue @venue Message content
+messageVenue venue:venue = MessageContent;
+
+//@description A message with a user contact @contact Message content
+messageContact contact:contact = MessageContent;
+
+//@description A message with a game @game Game
+messageGame game:game = MessageContent;
+
+//@description A message with an invoice from a bot @title Product title @param_description Product description @photo Product photo; may be null @currency Currency for the product price @total_amount Product total price in the minimal quantity of the currency
+//@start_parameter Unique invoice bot start_parameter. To share an invoice use the URL https://t.me/{bot_username}?start={start_parameter} @is_test True, if the invoice is a test invoice
+//@need_shipping_address True, if the shipping address should be specified @receipt_message_id The identifier of the message with the receipt, after the product has been purchased
+messageInvoice title:string description:string photo:photo currency:string total_amount:int53 start_parameter:string is_test:Bool need_shipping_address:Bool receipt_message_id:int53 = MessageContent;
+
+//@description A message with information about an ended call @discard_reason Reason why the call was discarded @duration Call duration, in seconds
+messageCall discard_reason:CallDiscardReason duration:int32 = MessageContent;
+
+//@description A newly created basic group @title Title of the basic group @member_user_ids User identifiers of members in the basic group
+messageBasicGroupChatCreate title:string member_user_ids:vector<int32> = MessageContent;
+
+//@description A newly created supergroup or channel @title Title of the supergroup or channel
+messageSupergroupChatCreate title:string = MessageContent;
+
+//@description An updated chat title @title New chat title
+messageChatChangeTitle title:string = MessageContent;
+
+//@description An updated chat photo @photo New chat photo
+messageChatChangePhoto photo:photo = MessageContent;
+
+//@description A deleted chat photo
+messageChatDeletePhoto = MessageContent;
+
+//@description New chat members were added @member_user_ids User identifiers of the new members
+messageChatAddMembers member_user_ids:vector<int32> = MessageContent;
+
+//@description A new member joined the chat by invite link
+messageChatJoinByLink = MessageContent;
+
+//@description A chat member was deleted @user_id User identifier of the deleted chat member
+messageChatDeleteMember user_id:int32 = MessageContent;
+
+//@description A basic group was upgraded to a supergroup and was deactivated as the result @supergroup_id Identifier of the supergroup to which the basic group was upgraded
+messageChatUpgradeTo supergroup_id:int32 = MessageContent;
+
+//@description A supergroup has been created from a basic group @title Title of the newly created supergroup @basic_group_id The identifier of the original basic group
+messageChatUpgradeFrom title:string basic_group_id:int32 = MessageContent;
+
+//@description A message has been pinned @message_id Identifier of the pinned message, can be an identifier of a deleted message
+messagePinMessage message_id:int53 = MessageContent;
+
+//@description A screenshot of a message in the chat has been taken
+messageScreenshotTaken = MessageContent;
+
+//@description The TTL (Time To Live) setting messages in a secret chat has been changed @ttl New TTL
+messageChatSetTtl ttl:int32 = MessageContent;
+
+//@description A non-standard action has happened in the chat @text Message text to be shown in the chat
+messageCustomServiceAction text:string = MessageContent;
+
+//@description A new high score was achieved in a game @game_message_id Identifier of the message with the game, can be an identifier of a deleted message @game_id Identifier of the game, may be different from the games presented in the message with the game @score New score
+messageGameScore game_message_id:int53 game_id:int64 score:int32 = MessageContent;
+
+//@description A payment has been completed @invoice_message_id Identifier of the message with the corresponding invoice; can be an identifier of a deleted message @currency Currency for the price of the product @total_amount Total price for the product, in the minimal quantity of the currency
+messagePaymentSuccessful invoice_message_id:int53 currency:string total_amount:int53 = MessageContent;
+
+//@description A payment has been completed; for bots only @invoice_message_id Identifier of the message with the corresponding invoice; can be an identifier of a deleted message @currency Currency for price of the product
+//@total_amount Total price for the product, in the minimal quantity of the currency @invoice_payload Invoice payload @shipping_option_id Identifier of the shipping option chosen by the user, may be empty if not applicable @order_info Information about the order; may be null
+//@telegram_payment_charge_id Telegram payment identifier @provider_payment_charge_id Provider payment identifier
+messagePaymentSuccessfulBot invoice_message_id:int53 currency:string total_amount:int53 invoice_payload:bytes shipping_option_id:string order_info:orderInfo telegram_payment_charge_id:string provider_payment_charge_id:string = MessageContent;
+
+//@description A contact has registered with Telegram
+messageContactRegistered = MessageContent;
+
+//@description The current user has connected a website by logging in using Telegram Login Widget on it @domain_name Domain name of the connected website
+messageWebsiteConnected domain_name:string = MessageContent;
+
+//@description Message content that is not supported by the client
+messageUnsupported = MessageContent;
+
+
+//@class TextEntityType @description Represents a part of the text which must be formatted differently
+
+//@description A mention of a user by their username
+textEntityTypeMention = TextEntityType;
+
+//@description A hashtag text, beginning with "#"
+textEntityTypeHashtag = TextEntityType;
+
+//@description A cashtag text, beginning with "$" and consisting of capital english letters (i.e. "$USD")
+textEntityTypeCashtag = TextEntityType;
+
+//@description A bot command, beginning with "/". This shouldn't be highlighted if there are no bots in the chat
+textEntityTypeBotCommand = TextEntityType;
+
+//@description An HTTP URL
+textEntityTypeUrl = TextEntityType;
+
+//@description An email address
+textEntityTypeEmailAddress = TextEntityType;
+
+//@description A bold text
+textEntityTypeBold = TextEntityType;
+
+//@description An italic text
+textEntityTypeItalic = TextEntityType;
+
+//@description Text that must be formatted as if inside a code HTML tag
+textEntityTypeCode = TextEntityType;
+
+//@description Text that must be formatted as if inside a pre HTML tag
+textEntityTypePre = TextEntityType;
+
+//@description Text that must be formatted as if inside pre, and code HTML tags @language Programming language of the code; as defined by the sender
+textEntityTypePreCode language:string = TextEntityType;
+
+//@description A text description shown instead of a raw URL @url URL to be opened when the link is clicked
+textEntityTypeTextUrl url:string = TextEntityType;
+
+//@description A text shows instead of a raw mention of the user (e.g., when the user has no username) @user_id Identifier of the mentioned user
+textEntityTypeMentionName user_id:int32 = TextEntityType;
+
+//@description A phone number
+textEntityTypePhoneNumber = TextEntityType;
+
+
+//@description A thumbnail to be sent along with a file; should be in JPEG or WEBP format for stickers, and less than 200 kB in size @thumbnail Thumbnail file to send. Sending thumbnails by file_id is currently not supported
+//@width Thumbnail width, usually shouldn't exceed 90. Use 0 if unknown @height Thumbnail height, usually shouldn't exceed 90. Use 0 if unknown
+inputThumbnail thumbnail:InputFile width:int32 height:int32 = InputThumbnail;
+
+
+//@class InputMessageContent @description The content of a message to send
+
+//@description A text message @text Formatted text to be sent. Only Bold, Italic, Code, Pre, PreCode and TextUrl entities are allowed to be specified manually
+//@disable_web_page_preview True, if rich web page previews for URLs in the message text should be disabled @clear_draft True, if a chat message draft should be deleted
+inputMessageText text:formattedText disable_web_page_preview:Bool clear_draft:Bool = InputMessageContent;
+
+//@description An animation message (GIF-style). @animation Animation file to be sent @thumbnail Animation thumbnail, if available @duration Duration of the animation, in seconds @width Width of the animation; may be replaced by the server @height Height of the animation; may be replaced by the server @caption Animation caption; 0-200 characters
+inputMessageAnimation animation:InputFile thumbnail:inputThumbnail duration:int32 width:int32 height:int32 caption:formattedText = InputMessageContent;
+
+//@description An audio message @audio Audio file to be sent @album_cover_thumbnail Thumbnail of the cover for the album, if available @duration Duration of the audio, in seconds; may be replaced by the server @title Title of the audio; 0-64 characters; may be replaced by the server
+//@performer Performer of the audio; 0-64 characters, may be replaced by the server @caption Audio caption; 0-200 characters
+inputMessageAudio audio:InputFile album_cover_thumbnail:inputThumbnail duration:int32 title:string performer:string caption:formattedText = InputMessageContent;
+
+//@description A document message (general file) @document Document to be sent @thumbnail Document thumbnail, if available @caption Document caption; 0-200 characters
+inputMessageDocument document:InputFile thumbnail:inputThumbnail caption:formattedText = InputMessageContent;
+
+//@description A photo message @photo Photo to send @thumbnail Photo thumbnail to be sent, this is sent to the other party in secret chats only @added_sticker_file_ids File identifiers of the stickers added to the photo, if applicable @width Photo width @height Photo height @caption Photo caption; 0-200 characters
+//@ttl Photo TTL (Time To Live), in seconds (0-60). A non-zero TTL can be specified only in private chats
+inputMessagePhoto photo:InputFile thumbnail:inputThumbnail added_sticker_file_ids:vector<int32> width:int32 height:int32 caption:formattedText ttl:int32 = InputMessageContent;
+
+//@description A sticker message @sticker Sticker to be sent @thumbnail Sticker thumbnail, if available @width Sticker width @height Sticker height
+inputMessageSticker sticker:InputFile thumbnail:inputThumbnail width:int32 height:int32 = InputMessageContent;
+
+//@description A video message @video Video to be sent @thumbnail Video thumbnail, if available @added_sticker_file_ids File identifiers of the stickers added to the video, if applicable
+//@duration Duration of the video, in seconds @width Video width @height Video height @supports_streaming True, if the video should be tried to be streamed
+//@caption Video caption; 0-200 characters @ttl Video TTL (Time To Live), in seconds (0-60). A non-zero TTL can be specified only in private chats
+inputMessageVideo video:InputFile thumbnail:inputThumbnail added_sticker_file_ids:vector<int32> duration:int32 width:int32 height:int32 supports_streaming:Bool caption:formattedText ttl:int32 = InputMessageContent;
+
+//@description A video note message @video_note Video note to be sent @thumbnail Video thumbnail, if available @duration Duration of the video, in seconds @length Video width and height; must be positive and not greater than 640
+inputMessageVideoNote video_note:InputFile thumbnail:inputThumbnail duration:int32 length:int32 = InputMessageContent;
+
+//@description A voice note message @voice_note Voice note to be sent @duration Duration of the voice note, in seconds @waveform Waveform representation of the voice note, in 5-bit format @caption Voice note caption; 0-200 characters
+inputMessageVoiceNote voice_note:InputFile duration:int32 waveform:bytes caption:formattedText = InputMessageContent;
+
+//@description A message with a location @location Location to be sent @live_period Period for which the location can be updated, in seconds; should bebetween 60 and 86400 for a live location and 0 otherwise
+inputMessageLocation location:location live_period:int32 = InputMessageContent;
+
+//@description A message with information about a venue @venue Venue to send
+inputMessageVenue venue:venue = InputMessageContent;
+
+//@description A message containing a user contact @contact Contact to send
+inputMessageContact contact:contact = InputMessageContent;
+
+//@description A message with a game; not supported for channels or secret chats @bot_user_id User identifier of the bot that owns the game @game_short_name Short name of the game
+inputMessageGame bot_user_id:int32 game_short_name:string = InputMessageContent;
+
+//@description A message with an invoice; can be used only by bots and only in private chats @invoice Invoice @title Product title; 1-32 characters @param_description Product description; 0-255 characters @photo_url Product photo URL; optional @photo_size Product photo size @photo_width Product photo width @photo_height Product photo height
+//@payload The invoice payload @provider_token Payment provider token @provider_data JSON-encoded data about the invoice, which will be shared with the payment provider @start_parameter Unique invoice bot start_parameter for the generation of this invoice
+inputMessageInvoice invoice:invoice title:string description:string photo_url:string photo_size:int32 photo_width:int32 photo_height:int32 payload:bytes provider_token:string provider_data:string start_parameter:string = InputMessageContent;
+
+//@description A forwarded message @from_chat_id Identifier for the chat this forwarded message came from @message_id Identifier of the message to forward @in_game_share True, if a game message should be shared within a launched game; applies only to game messages
+inputMessageForwarded from_chat_id:int53 message_id:int53 in_game_share:Bool = InputMessageContent;
+
+
+//@class SearchMessagesFilter @description Represents a filter for message search results
+
+//@description Returns all found messages, no filter is applied
+searchMessagesFilterEmpty = SearchMessagesFilter;
+
+//@description Returns only animation messages
+searchMessagesFilterAnimation = SearchMessagesFilter;
+
+//@description Returns only audio messages
+searchMessagesFilterAudio = SearchMessagesFilter;
+
+//@description Returns only document messages
+searchMessagesFilterDocument = SearchMessagesFilter;
+
+//@description Returns only photo messages
+searchMessagesFilterPhoto = SearchMessagesFilter;
+
+//@description Returns only video messages
+searchMessagesFilterVideo = SearchMessagesFilter;
+
+//@description Returns only voice note messages
+searchMessagesFilterVoiceNote = SearchMessagesFilter;
+
+//@description Returns only photo and video messages
+searchMessagesFilterPhotoAndVideo = SearchMessagesFilter;
+
+//@description Returns only messages containing URLs
+searchMessagesFilterUrl = SearchMessagesFilter;
+
+//@description Returns only messages containing chat photos
+searchMessagesFilterChatPhoto = SearchMessagesFilter;
+
+//@description Returns only call messages
+searchMessagesFilterCall = SearchMessagesFilter;
+
+//@description Returns only incoming call messages with missed/declined discard reasons
+searchMessagesFilterMissedCall = SearchMessagesFilter;
+
+//@description Returns only video note messages
+searchMessagesFilterVideoNote = SearchMessagesFilter;
+
+//@description Returns only voice and video note messages
+searchMessagesFilterVoiceAndVideoNote = SearchMessagesFilter;
+
+//@description Returns only messages with mentions of the current user, or messages that are replies to their messages
+searchMessagesFilterMention = SearchMessagesFilter;
+
+//@description Returns only messages with unread mentions of the current user or messages that are replies to their messages. When using this filter the results can't be additionally filtered by a query or by the sending user
+searchMessagesFilterUnreadMention = SearchMessagesFilter;
+
+
+//@class ChatAction @description Describes the different types of activity in a chat
+
+//@description The user is typing a message
+chatActionTyping = ChatAction;
+//@description The user is recording a video
+chatActionRecordingVideo = ChatAction;
+//@description The user is uploading a video @progress Upload progress, as a percentage
+chatActionUploadingVideo progress:int32 = ChatAction;
+//@description The user is recording a voice note
+chatActionRecordingVoiceNote = ChatAction;
+//@description The user is uploading a voice note @progress Upload progress, as a percentage
+chatActionUploadingVoiceNote progress:int32 = ChatAction;
+//@description The user is uploading a photo @progress Upload progress, as a percentage
+chatActionUploadingPhoto progress:int32 = ChatAction;
+//@description The user is uploading a document @progress Upload progress, as a percentage
+chatActionUploadingDocument progress:int32 = ChatAction;
+//@description The user is picking a location or venue to send
+chatActionChoosingLocation = ChatAction;
+//@description The user is picking a contact to send
+chatActionChoosingContact = ChatAction;
+//@description The user has started to play a game
+chatActionStartPlayingGame = ChatAction;
+//@description The user is recording a video note
+chatActionRecordingVideoNote = ChatAction;
+//@description The user is uploading a video note @progress Upload progress, as a percentage
+chatActionUploadingVideoNote progress:int32 = ChatAction;
+//@description The user has cancelled the previous action
+chatActionCancel = ChatAction;
+
+
+//@class UserStatus @description Describes the last time the user was online
+
+//@description The user status was never changed
+userStatusEmpty = UserStatus;
+
+//@description The user is online @expires Point in time (Unix timestamp) when the user's online status will expire
+userStatusOnline expires:int32 = UserStatus;
+
+//@description The user is offline @was_online Point in time (Unix timestamp) when the user was last online
+userStatusOffline was_online:int32 = UserStatus;
+
+//@description The user was online recently
+userStatusRecently = UserStatus;
+
+//@description The user is offline, but was online last week
+userStatusLastWeek = UserStatus;
+
+//@description The user is offline, but was online last month
+userStatusLastMonth = UserStatus;
+
+
+//@description Represents a list of stickers @stickers List of stickers
+stickers stickers:vector<sticker> = Stickers;
+
+//@description Represents a list of all emoji corresponding to a sticker in a sticker set. The list is only for informational purposes, because a sticker is always sent with a fixed emoji from the corresponding Sticker object @emojis List of emojis
+stickerEmojis emojis:vector<string> = StickerEmojis;
+
+//@description Represents a sticker set @id Identifier of the sticker set @title Title of the sticker set @name Name of the sticker set @is_installed True, if the sticker set has been installed by the current user
+//@is_archived True, if the sticker set has been archived. A sticker set can't be installed and archived simultaneously @is_official True, if the sticker set is official @is_masks True, if the stickers in the set are masks
+//@is_viewed True for already viewed trending sticker sets @stickers List of stickers in this set @emojis A list of emoji corresponding to the stickers in the same order
+stickerSet id:int64 title:string name:string is_installed:Bool is_archived:Bool is_official:Bool is_masks:Bool is_viewed:Bool stickers:vector<sticker> emojis:vector<stickerEmojis> = StickerSet;
+
+//@description Represents short information about a sticker set @id Identifier of the sticker set @title Title of the sticker set @name Name of the sticker set @is_installed True, if the sticker set has been installed by current user
+//@is_archived True, if the sticker set has been archived. A sticker set can't be installed and archived simultaneously @is_official True, if the sticker set is official @is_masks True, if the stickers in the set are masks
+//@is_viewed True for already viewed trending sticker sets @size Total number of stickers in the set @covers Contains up to the first 5 stickers from the set, depending on the context. If the client needs more stickers the full set should be requested
+stickerSetInfo id:int64 title:string name:string is_installed:Bool is_archived:Bool is_official:Bool is_masks:Bool is_viewed:Bool size:int32 covers:vector<sticker> = StickerSetInfo;
+
+//@description Represents a list of sticker sets @total_count Approximate total number of sticker sets found @sets List of sticker sets
+stickerSets total_count:int32 sets:vector<stickerSetInfo> = StickerSets;
+
+
+//@class CallDiscardReason @description Describes the reason why a call was discarded
+
+//@description The call wasn't discarded, or the reason is unknown
+callDiscardReasonEmpty = CallDiscardReason;
+
+//@description The call was ended before the conversation started. It was cancelled by the caller or missed by the other party
+callDiscardReasonMissed = CallDiscardReason;
+
+//@description The call was ended before the conversation started. It was declined by the other party
+callDiscardReasonDeclined = CallDiscardReason;
+
+//@description The call was ended during the conversation because the users were disconnected
+callDiscardReasonDisconnected = CallDiscardReason;
+
+//@description The call was ended because one of the parties hung up
+callDiscardReasonHungUp = CallDiscardReason;
+
+
+//@description Specifies the supported call protocols @udp_p2p True, if UDP peer-to-peer connections are supported @udp_reflector True, if connection through UDP reflectors is supported @min_layer Minimum supported API layer; use 65 @max_layer Maximum supported API layer; use 65
+callProtocol udp_p2p:Bool udp_reflector:Bool min_layer:int32 max_layer:int32 = CallProtocol;
+
+//@description Describes the address of UDP reflectors @id Reflector identifier @ip IPv4 reflector address @ipv6 IPv6 reflector address @port Reflector port number @peer_tag Connection peer tag
+callConnection id:int64 ip:string ipv6:string port:int32 peer_tag:bytes = CallConnection;
+
+
+//@description Contains the call identifier @id Call identifier
+callId id:int32 = CallId;
+
+
+//@class CallState @description Describes the current call state
+
+//@description The call is pending, waiting to be accepted by a user @is_created True, if the call has already been created by the server @is_received True, if the call has already been received by the other party
+callStatePending is_created:Bool is_received:Bool = CallState;
+
+//@description The call has been answered and encryption keys are being exchanged
+callStateExchangingKeys = CallState;
+
+//@description The call is ready to use @protocol Call protocols supported by the peer @connections Available UDP reflectors @config A JSON-encoded call config @encryption_key Call encryption key @emojis Encryption key emojis fingerprint
+callStateReady protocol:callProtocol connections:vector<callConnection> config:string encryption_key:bytes emojis:vector<string> = CallState;
+
+//@description The call is hanging up after discardCall has been called
+callStateHangingUp = CallState;
+
+//@description The call has ended successfully @reason The reason, why the call has ended @need_rating True, if the call rating should be sent to the server @need_debug_information True, if the call debug information should be sent to the server
+callStateDiscarded reason:CallDiscardReason need_rating:Bool need_debug_information:Bool = CallState;
+
+//@description The call has ended with an error @error Error. An error with the code 4005000 will be returned if an outgoing call is missed because of an expired timeout
+callStateError error:error = CallState;
+
+
+//@description Describes a call @id Call identifier, not persistent @user_id Peer user identifier @is_outgoing True, if the call is outgoing @state Call state
+call id:int32 user_id:int32 is_outgoing:Bool state:CallState = Call;
+
+
+//@description Represents a list of animations @animations List of animations
+animations animations:vector<animation> = Animations;
+
+
+//@description Represents the result of an ImportContacts request @user_ids User identifiers of the imported contacts in the same order as they were specified in the request; 0 if the contact is not yet a registered user
+//@importer_count The number of users that imported the corresponding contact; 0 for already registered users or if unavailable
+importedContacts user_ids:vector<int32> importer_count:vector<int32> = ImportedContacts;
+
+
+//@class InputInlineQueryResult @description Represents a single result of an inline query; for bots only
+
+//@description Represents a link to an animated GIF @id Unique identifier of the query result @title Title of the query result @thumbnail_url URL of the static result thumbnail (JPEG or GIF), if it exists
+//@gif_url The URL of the GIF-file (file size must not exceed 1MB) @gif_duration Duration of the GIF, in seconds @gif_width Width of the GIF @gif_height Height of the GIF
+//@reply_markup The message reply markup. Must be of type replyMarkupInlineKeyboard or null
+//@input_message_content The content of the message to be sent. Must be one of the following types: InputMessageText, InputMessageAnimation, InputMessageLocation, InputMessageVenue or InputMessageContact
+inputInlineQueryResultAnimatedGif id:string title:string thumbnail_url:string gif_url:string gif_duration:int32 gif_width:int32 gif_height:int32 reply_markup:ReplyMarkup input_message_content:InputMessageContent = InputInlineQueryResult;
+
+//@description Represents a link to an animated (i.e. without sound) H.264/MPEG-4 AVC video @id Unique identifier of the query result @title Title of the result @thumbnail_url URL of the static result thumbnail (JPEG or GIF), if it exists
+//@mpeg4_url The URL of the MPEG4-file (file size must not exceed 1MB) @mpeg4_duration Duration of the video, in seconds @mpeg4_width Width of the video @mpeg4_height Height of the video
+//@reply_markup The message reply markup. Must be of type replyMarkupInlineKeyboard or null
+//@input_message_content The content of the message to be sent. Must be one of the following types: InputMessageText, InputMessageAnimation, InputMessageLocation, InputMessageVenue or InputMessageContact
+inputInlineQueryResultAnimatedMpeg4 id:string title:string thumbnail_url:string mpeg4_url:string mpeg4_duration:int32 mpeg4_width:int32 mpeg4_height:int32 reply_markup:ReplyMarkup input_message_content:InputMessageContent = InputInlineQueryResult;
+
+//@description Represents a link to an article or web page @id Unique identifier of the query result @url URL of the result, if it exists @hide_url True, if the URL must be not shown @title Title of the result
+//@param_description A short description of the result @thumbnail_url URL of the result thumbnail, if it exists @thumbnail_width Thumbnail width, if known @thumbnail_height Thumbnail height, if known
+//@reply_markup The message reply markup. Must be of type replyMarkupInlineKeyboard or null
+//@input_message_content The content of the message to be sent. Must be one of the following types: InputMessageText, InputMessageLocation, InputMessageVenue or InputMessageContact
+inputInlineQueryResultArticle id:string url:string hide_url:Bool title:string description:string thumbnail_url:string thumbnail_width:int32 thumbnail_height:int32 reply_markup:ReplyMarkup input_message_content:InputMessageContent = InputInlineQueryResult;
+
+//@description Represents a link to an MP3 audio file @id Unique identifier of the query result @title Title of the audio file @performer Performer of the audio file
+//@audio_url The URL of the audio file @audio_duration Audio file duration, in seconds
+//@reply_markup The message reply markup. Must be of type replyMarkupInlineKeyboard or null
+//@input_message_content The content of the message to be sent. Must be one of the following types: InputMessageText, InputMessageAudio, InputMessageLocation, InputMessageVenue or InputMessageContact
+inputInlineQueryResultAudio id:string title:string performer:string audio_url:string audio_duration:int32 reply_markup:ReplyMarkup input_message_content:InputMessageContent = InputInlineQueryResult;
+
+//@description Represents a user contact @id Unique identifier of the query result @contact User contact @thumbnail_url URL of the result thumbnail, if it exists @thumbnail_width Thumbnail width, if known @thumbnail_height Thumbnail height, if known
+//@reply_markup The message reply markup. Must be of type replyMarkupInlineKeyboard or null
+//@input_message_content The content of the message to be sent. Must be one of the following types: InputMessageText, InputMessageLocation, InputMessageVenue or InputMessageContact
+inputInlineQueryResultContact id:string contact:contact thumbnail_url:string thumbnail_width:int32 thumbnail_height:int32 reply_markup:ReplyMarkup input_message_content:InputMessageContent = InputInlineQueryResult;
+
+//@description Represents a link to a file @id Unique identifier of the query result @title Title of the resulting file @param_description Short description of the result, if known @document_url URL of the file @mime_type MIME type of the file content; only "application/pdf" and "application/zip" are currently allowed
+//@thumbnail_url The URL of the file thumbnail, if it exists @thumbnail_width Width of the thumbnail @thumbnail_height Height of the thumbnail
+//@reply_markup The message reply markup. Must be of type replyMarkupInlineKeyboard or null
+//@input_message_content The content of the message to be sent. Must be one of the following types: InputMessageText, InputMessageDocument, InputMessageLocation, InputMessageVenue or InputMessageContact
+inputInlineQueryResultDocument id:string title:string description:string document_url:string mime_type:string thumbnail_url:string thumbnail_width:int32 thumbnail_height:int32 reply_markup:ReplyMarkup input_message_content:InputMessageContent = InputInlineQueryResult;
+
+//@description Represents a game @id Unique identifier of the query result @game_short_name Short name of the game @reply_markup Message reply markup. Must be of type replyMarkupInlineKeyboard or null
+inputInlineQueryResultGame id:string game_short_name:string reply_markup:ReplyMarkup = InputInlineQueryResult;
+
+//@description Represents a point on the map @id Unique identifier of the query result @location Location result @live_period Amount of time relative to the message sent time until the location can be updated, in seconds @title Title of the result @thumbnail_url URL of the result thumbnail, if it exists @thumbnail_width Thumbnail width, if known @thumbnail_height Thumbnail height, if known
+//@reply_markup The message reply markup. Must be of type replyMarkupInlineKeyboard or null
+//@input_message_content The content of the message to be sent. Must be one of the following types: InputMessageText, InputMessageLocation, InputMessageVenue or InputMessageContact
+inputInlineQueryResultLocation id:string location:location live_period:int32 title:string thumbnail_url:string thumbnail_width:int32 thumbnail_height:int32 reply_markup:ReplyMarkup input_message_content:InputMessageContent = InputInlineQueryResult;
+
+//@description Represents link to a JPEG image @id Unique identifier of the query result @title Title of the result, if known @param_description A short description of the result, if known @thumbnail_url URL of the photo thumbnail, if it exists
+//@photo_url The URL of the JPEG photo (photo size must not exceed 5MB) @photo_width Width of the photo @photo_height Height of the photo
+//@reply_markup The message reply markup. Must be of type replyMarkupInlineKeyboard or null
+//@input_message_content The content of the message to be sent. Must be one of the following types: InputMessageText, InputMessagePhoto, InputMessageLocation, InputMessageVenue or InputMessageContact
+inputInlineQueryResultPhoto id:string title:string description:string thumbnail_url:string photo_url:string photo_width:int32 photo_height:int32 reply_markup:ReplyMarkup input_message_content:InputMessageContent = InputInlineQueryResult;
+
+//@description Represents a link to a WEBP sticker @id Unique identifier of the query result @thumbnail_url URL of the sticker thumbnail, if it exists
+//@sticker_url The URL of the WEBP sticker (sticker file size must not exceed 5MB) @sticker_width Width of the sticker @sticker_height Height of the sticker
+//@reply_markup The message reply markup. Must be of type replyMarkupInlineKeyboard or null
+//@input_message_content The content of the message to be sent. Must be one of the following types: InputMessageText, inputMessageSticker, InputMessageLocation, InputMessageVenue or InputMessageContact
+inputInlineQueryResultSticker id:string thumbnail_url:string sticker_url:string sticker_width:int32 sticker_height:int32 reply_markup:ReplyMarkup input_message_content:InputMessageContent = InputInlineQueryResult;
+
+//@description Represents information about a venue @id Unique identifier of the query result @venue Venue result @thumbnail_url URL of the result thumbnail, if it exists @thumbnail_width Thumbnail width, if known @thumbnail_height Thumbnail height, if known
+//@reply_markup The message reply markup. Must be of type replyMarkupInlineKeyboard or null
+//@input_message_content The content of the message to be sent. Must be one of the following types: InputMessageText, InputMessageLocation, InputMessageVenue or InputMessageContact
+inputInlineQueryResultVenue id:string venue:venue thumbnail_url:string thumbnail_width:int32 thumbnail_height:int32 reply_markup:ReplyMarkup input_message_content:InputMessageContent = InputInlineQueryResult;
+
+//@description Represents a link to a page containing an embedded video player or a video file @id Unique identifier of the query result @title Title of the result @param_description A short description of the result, if known
+//@thumbnail_url The URL of the video thumbnail (JPEG), if it exists @video_url URL of the embedded video player or video file @mime_type MIME type of the content of the video URL, only "text/html" or "video/mp4" are currently supported
+//@video_width Width of the video @video_height Height of the video @video_duration Video duration, in seconds
+//@reply_markup The message reply markup. Must be of type replyMarkupInlineKeyboard or null
+//@input_message_content The content of the message to be sent. Must be one of the following types: InputMessageText, InputMessageVideo, InputMessageLocation, InputMessageVenue or InputMessageContact
+inputInlineQueryResultVideo id:string title:string description:string thumbnail_url:string video_url:string mime_type:string video_width:int32 video_height:int32 video_duration:int32 reply_markup:ReplyMarkup input_message_content:InputMessageContent = InputInlineQueryResult;
+
+//@description Represents a link to an opus-encoded audio file within an OGG container, single channel audio @id Unique identifier of the query result @title Title of the voice note
+//@voice_note_url The URL of the voice note file @voice_note_duration Duration of the voice note, in seconds
+//@reply_markup The message reply markup. Must be of type replyMarkupInlineKeyboard or null
+//@input_message_content The content of the message to be sent. Must be one of the following types: InputMessageText, InputMessageVoiceNote, InputMessageLocation, InputMessageVenue or InputMessageContact
+inputInlineQueryResultVoiceNote id:string title:string voice_note_url:string voice_note_duration:int32 reply_markup:ReplyMarkup input_message_content:InputMessageContent = InputInlineQueryResult;
+
+
+//@class InlineQueryResult @description Represents a single result of an inline query
+
+//@description Represents a link to an article or web page @id Unique identifier of the query result @url URL of the result, if it exists @hide_url True, if the URL must be not shown @title Title of the result
+//@param_description A short description of the result @thumbnail Result thumbnail; may be null
+inlineQueryResultArticle id:string url:string hide_url:Bool title:string description:string thumbnail:photoSize = InlineQueryResult;
+
+//@description Represents a user contact @id Unique identifier of the query result @contact A user contact @thumbnail Result thumbnail; may be null
+inlineQueryResultContact id:string contact:contact thumbnail:photoSize = InlineQueryResult;
+
+//@description Represents a point on the map @id Unique identifier of the query result @location Location result @title Title of the result @thumbnail Result thumbnail; may be null
+inlineQueryResultLocation id:string location:location title:string thumbnail:photoSize = InlineQueryResult;
+
+//@description Represents information about a venue @id Unique identifier of the query result @venue Venue result @thumbnail Result thumbnail; may be null
+inlineQueryResultVenue id:string venue:venue thumbnail:photoSize = InlineQueryResult;
+
+//@description Represents information about a game @id Unique identifier of the query result @game Game result
+inlineQueryResultGame id:string game:game = InlineQueryResult;
+
+//@description Represents an animation file @id Unique identifier of the query result @animation Animation file @title Animation title
+inlineQueryResultAnimation id:string animation:animation title:string = InlineQueryResult;
+
+//@description Represents an audio file @id Unique identifier of the query result @audio Audio file
+inlineQueryResultAudio id:string audio:audio = InlineQueryResult;
+
+//@description Represents a document @id Unique identifier of the query result @document Document @title Document title @param_description Document description
+inlineQueryResultDocument id:string document:document title:string description:string = InlineQueryResult;
+
+//@description Represents a photo @id Unique identifier of the query result @photo Photo @title Title of the result, if known @param_description A short description of the result, if known
+inlineQueryResultPhoto id:string photo:photo title:string description:string = InlineQueryResult;
+
+//@description Represents a sticker @id Unique identifier of the query result @sticker Sticker
+inlineQueryResultSticker id:string sticker:sticker = InlineQueryResult;
+
+//@description Represents a video @id Unique identifier of the query result @video Video @title Title of the video @param_description Description of the video
+inlineQueryResultVideo id:string video:video title:string description:string = InlineQueryResult;
+
+//@description Represents a voice note @id Unique identifier of the query result @voice_note Voice note @title Title of the voice note
+inlineQueryResultVoiceNote id:string voice_note:voiceNote title:string = InlineQueryResult;
+
+
+//@description Represents the results of the inline query. Use sendInlineQueryResultMessage to send the result of the query @inline_query_id Unique identifier of the inline query @next_offset The offset for the next request. If empty, there are no more results @results Results of the query
+//@switch_pm_text If non-empty, this text should be shown on the button, which opens a private chat with the bot and sends the bot a start message with the switch_pm_parameter @switch_pm_parameter Parameter for the bot start message
+inlineQueryResults inline_query_id:int64 next_offset:string results:vector<InlineQueryResult> switch_pm_text:string switch_pm_parameter:string = InlineQueryResults;
+
+
+//@class CallbackQueryPayload @description Represents a payload of a callback query
+
+//@description The payload from a general callback button @data Data that was attached to the callback button
+callbackQueryPayloadData data:bytes = CallbackQueryPayload;
+
+//@description The payload from a game callback button @game_short_name A short name of the game that was attached to the callback button
+callbackQueryPayloadGame game_short_name:string = CallbackQueryPayload;
+
+
+//@description Contains a bot's answer to a callback query @text Text of the answer @show_alert True, if an alert should be shown to the user instead of a toast notification @url URL to be opened
+callbackQueryAnswer text:string show_alert:Bool url:string = CallbackQueryAnswer;
+
+
+//@description Contains the result of a custom request @result A JSON-serialized result
+customRequestResult result:string = CustomRequestResult;
+
+
+//@description Contains one row of the game high score table @position Position in the high score table @user_id User identifier @score User score
+gameHighScore position:int32 user_id:int32 score:int32 = GameHighScore;
+
+//@description Contains a list of game high scores @scores A list of game high scores
+gameHighScores scores:vector<gameHighScore> = GameHighScores;
+
+
+//@class ChatEventAction @description Represents a chat event
+
+//@description A message was edited @old_message The original message before the edit @new_message The message after it was edited
+chatEventMessageEdited old_message:message new_message:message = ChatEventAction;
+
+//@description A message was deleted @message Deleted message
+chatEventMessageDeleted message:message = ChatEventAction;
+
+//@description A message was pinned @message Pinned message
+chatEventMessagePinned message:message = ChatEventAction;
+
+//@description A message was unpinned
+chatEventMessageUnpinned = ChatEventAction;
+
+//@description A new member joined the chat
+chatEventMemberJoined = ChatEventAction;
+
+//@description A member left the chat
+chatEventMemberLeft = ChatEventAction;
+
+//@description A new chat member was invited @user_id New member user identifier @status New member status
+chatEventMemberInvited user_id:int32 status:ChatMemberStatus = ChatEventAction;
+
+//@description A chat member has gained/lost administrator status, or the list of their administrator privileges has changed @user_id Chat member user identifier @old_status Previous status of the chat member @new_status New status of the chat member
+chatEventMemberPromoted user_id:int32 old_status:ChatMemberStatus new_status:ChatMemberStatus = ChatEventAction;
+
+//@description A chat member was restricted/unrestricted or banned/unbanned, or the list of their restrictions has changed @user_id Chat member user identifier @old_status Previous status of the chat member @new_status New status of the chat member
+chatEventMemberRestricted user_id:int32 old_status:ChatMemberStatus new_status:ChatMemberStatus = ChatEventAction;
+
+//@description The chat title was changed @old_title Previous chat title @new_title New chat title
+chatEventTitleChanged old_title:string new_title:string = ChatEventAction;
+
+//@description The chat description was changed @old_description Previous chat description @new_description New chat description
+chatEventDescriptionChanged old_description:string new_description:string = ChatEventAction;
+
+//@description The chat username was changed @old_username Previous chat username @new_username New chat username
+chatEventUsernameChanged old_username:string new_username:string = ChatEventAction;
+
+//@description The chat photo was changed @old_photo Previous chat photo value; may be null @new_photo New chat photo value; may be null
+chatEventPhotoChanged old_photo:chatPhoto new_photo:chatPhoto = ChatEventAction;
+
+//@description The anyone_can_invite setting of a supergroup chat was toggled @anyone_can_invite New value of anyone_can_invite
+chatEventInvitesToggled anyone_can_invite:Bool = ChatEventAction;
+
+//@description The sign_messages setting of a channel was toggled @sign_messages New value of sign_messages
+chatEventSignMessagesToggled sign_messages:Bool = ChatEventAction;
+
+//@description The supergroup sticker set was changed @old_sticker_set_id Previous identifier of the chat sticker set; 0 if none @new_sticker_set_id New identifier of the chat sticker set; 0 if none
+chatEventStickerSetChanged old_sticker_set_id:int64 new_sticker_set_id:int64 = ChatEventAction;
+
+//@description The is_all_history_available setting of a supergroup was toggled @is_all_history_available New value of is_all_history_available
+chatEventIsAllHistoryAvailableToggled is_all_history_available:Bool = ChatEventAction;
+
+//@description Represents a chat event @id Chat event identifier @date Point in time (Unix timestamp) when the event happened @user_id Identifier of the user who performed the action that triggered the event @action Action performed by the user
+chatEvent id:int64 date:int32 user_id:int32 action:ChatEventAction = ChatEvent;
+
+//@description Contains a list of chat events @events List of events
+chatEvents events:vector<chatEvent> = ChatEvents;
+
+//@description Represents a set of filters used to obtain a chat event log
+//@message_edits True, if message edits should be returned
+//@message_deletions True, if message deletions should be returned
+//@message_pins True, if pin/unpin events should be returned
+//@member_joins True, if members joining events should be returned
+//@member_leaves True, if members leaving events should be returned
+//@member_invites True, if invited member events should be returned
+//@member_promotions True, if member promotion/demotion events should be returned
+//@member_restrictions True, if member restricted/unrestricted/banned/unbanned events should be returned
+//@info_changes True, if changes in chat information should be returned
+//@setting_changes True, if changes in chat settings should be returned
+chatEventLogFilters message_edits:Bool message_deletions:Bool message_pins:Bool member_joins:Bool member_leaves:Bool member_invites:Bool member_promotions:Bool member_restrictions:Bool info_changes:Bool setting_changes:Bool = ChatEventLogFilters;
+
+
+//@class DeviceToken @description Represents a data needed to subscribe for push notifications. To use specific push notification service, you must specify the correct application platform and upload valid server authentication data at https://my.telegram.org
+
+//@description A token for Google Cloud Messaging @token Device registration token, may be empty to de-register a device
+deviceTokenGoogleCloudMessaging token:string = DeviceToken;
+
+//@description A token for Apple Push Notification service @device_token Device token, may be empty to de-register a device @is_app_sandbox True, if App Sandbox is enabled
+deviceTokenApplePush device_token:string is_app_sandbox:Bool = DeviceToken;
+
+//@description A token for Apple Push Notification service VoIP notifications @device_token Device token, may be empty to de-register a device @is_app_sandbox True, if App Sandbox is enabled
+deviceTokenApplePushVoIP device_token:string is_app_sandbox:Bool = DeviceToken;
+
+//@description A token for Windows Push Notification Services @access_token The access token that will be used to send notifications, may be empty to de-register a device
+deviceTokenWindowsPush access_token:string = DeviceToken;
+
+//@description A token for Microsoft Push Notification Service @channel_uri Push notification channel URI, may be empty to de-register a device
+deviceTokenMicrosoftPush channel_uri:string = DeviceToken;
+
+//@description A token for Microsoft Push Notification Service VoIP channel @channel_uri Push notification channel URI, may be empty to de-register a device
+deviceTokenMicrosoftPushVoIP channel_uri:string = DeviceToken;
+
+//@description A token for web Push API @endpoint Absolute URL exposed by the push service where the application server can send push messages, may be empty to de-register a device
+//@p256dh_base64url Base64url-encoded P-256 elliptic curve Diffie-Hellman public key @auth_base64url Base64url-encoded authentication secret
+deviceTokenWebPush endpoint:string p256dh_base64url:string auth_base64url:string = DeviceToken;
+
+//@description A token for Simple Push API for Firefox OS @endpoint Absolute URL exposed by the push service where the application server can send push messages, may be empty to de-register a device
+deviceTokenSimplePush endpoint:string = DeviceToken;
+
+//@description A token for Ubuntu Push Client service @token Token, may be empty to de-register a device
+deviceTokenUbuntuPush token:string = DeviceToken;
+
+//@description A token for BlackBerry Push Service @token Token, may be empty to de-register a device
+deviceTokenBlackBerryPush token:string = DeviceToken;
+
+//@description A token for Tizen Push Service @reg_id Push service registration identifier, may be empty to de-register a device
+deviceTokenTizenPush reg_id:string = DeviceToken;
+
+
+//@description Contains information about a wallpaper @id Unique persistent wallpaper identifier @sizes Available variants of the wallpaper in different sizes. These photos can only be downloaded; they can't be sent in a message @color Main color of the wallpaper in RGB24 format; should be treated as background color if no photos are specified
+wallpaper id:int32 sizes:vector<photoSize> color:int32 = Wallpaper;
+
+//@description Contains a list of wallpapers @wallpapers A list of wallpapers
+wallpapers wallpapers:vector<wallpaper> = Wallpapers;
+
+
+//@description Contains a list of hashtags @hashtags A list of hashtags
+hashtags hashtags:vector<string> = Hashtags;
+
+
+//@class CheckChatUsernameResult @description Represents result of checking whether a username can be set for a chat
+
+//@description The username can be set
+checkChatUsernameResultOk = CheckChatUsernameResult;
+
+//@description The username is invalid
+checkChatUsernameResultUsernameInvalid = CheckChatUsernameResult;
+
+//@description The username is occupied
+checkChatUsernameResultUsernameOccupied = CheckChatUsernameResult;
+
+//@description The user has too much public chats, one of them should be made private first
+checkChatUsernameResultPublicChatsTooMuch = CheckChatUsernameResult;
+
+//@description The user can't be a member of a public supergroup
+checkChatUsernameResultPublicGroupsUnavailable = CheckChatUsernameResult;
+
+
+//@class OptionValue @description Represents the value of an option
+
+//@description Boolean option @value The value of the option
+optionValueBoolean value:Bool = OptionValue;
+
+//@description An unknown option or an option which has a default value
+optionValueEmpty = OptionValue;
+
+//@description An integer option @value The value of the option
+optionValueInteger value:int32 = OptionValue;
+
+//@description A string option @value The value of the option
+optionValueString value:string = OptionValue;
+
+
+//@class UserPrivacySettingRule @description Represents a single rule for managing privacy settings
+
+//@description A rule to allow all users to do something
+userPrivacySettingRuleAllowAll = UserPrivacySettingRule;
+
+//@description A rule to allow all of a user's contacts to do something
+userPrivacySettingRuleAllowContacts = UserPrivacySettingRule;
+
+//@description A rule to allow certain specified users to do something @user_ids The user identifiers
+userPrivacySettingRuleAllowUsers user_ids:vector<int32> = UserPrivacySettingRule;
+
+//@description A rule to restrict all users from doing something
+userPrivacySettingRuleRestrictAll = UserPrivacySettingRule;
+
+//@description A rule to restrict all contacts of a user from doing something
+userPrivacySettingRuleRestrictContacts = UserPrivacySettingRule;
+
+//@description A rule to restrict all specified users from doing something @user_ids The user identifiers
+userPrivacySettingRuleRestrictUsers user_ids:vector<int32> = UserPrivacySettingRule;
+
+//@description A list of privacy rules. Rules are matched in the specified order. The first matched rule defines the privacy setting for a given user. If no rule matches, the action is not allowed @rules A list of rules
+userPrivacySettingRules rules:vector<UserPrivacySettingRule> = UserPrivacySettingRules;
+
+//@class UserPrivacySetting @description Describes available user privacy settings
+
+//@description A privacy setting for managing whether the user's online status is visible
+userPrivacySettingShowStatus = UserPrivacySetting;
+
+//@description A privacy setting for managing whether the user can be invited to chats
+userPrivacySettingAllowChatInvites = UserPrivacySetting;
+
+//@description A privacy setting for managing whether the user can be called
+userPrivacySettingAllowCalls = UserPrivacySetting;
+
+
+//@description Contains information about the period of inactivity after which the current user's account will automatically be deleted @days Number of days of inactivity before the account will be flagged for deletion; should range from 30-366 days
+accountTtl days:int32 = AccountTtl;
+
+
+//@description Contains information about one session in a Telegram application used by the current user @id Session identifier @is_current True, if this session is the current session
+//@api_id Telegram API identifier, as provided by the application @application_name Name of the application, as provided by the application
+//@application_version The version of the application, as provided by the application @is_official_application True, if the application is an official application or uses the api_id of an official application
+//@device_model Model of the device the application has been run or is running on, as provided by the application @platform Operating system the application has been run or is running on, as provided by the application
+//@system_version Version of the operating system the application has been run or is running on, as provided by the application @log_in_date Point in time (Unix timestamp) when the user has logged in
+//@last_active_date Point in time (Unix timestamp) when the session was last used @ip IP address from which the session was created, in human-readable format
+//@country A two-letter country code for the country from which the session was created, based on the IP address @region Region code from which the session was created, based on the IP address
+session id:int64 is_current:Bool api_id:int32 application_name:string application_version:string is_official_application:Bool device_model:string platform:string system_version:string log_in_date:int32 last_active_date:int32 ip:string country:string region:string = Session;
+
+//@description Contains a list of sessions @sessions List of sessions
+sessions sessions:vector<session> = Sessions;
+
+
+//@description Contains information about one website the current user is logged in with Telegram
+//@id Website identifier
+//@domain_name The domain name of the website
+//@bot_user_id User identifier of a bot linked with the website
+//@browser The version of a browser used to log in
+//@platform Operating system the browser is running on
+//@log_in_date Point in time (Unix timestamp) when the user was logged in
+//@last_active_date Point in time (Unix timestamp) when obtained authorization was last used
+//@ip IP address from which the user was logged in, in human-readable format
+//@location Human-readable description of a country and a region, from which the user was logged in, based on the IP address
+connectedWebsite id:int64 domain_name:string bot_user_id:int32 browser:string platform:string log_in_date:int32 last_active_date:int32 ip:string location:string = ConnectedWebsite;
+
+//@description Contains a list of websites the current user is logged in with Telegram @websites List of connected websites
+connectedWebsites websites:vector<connectedWebsite> = ConnectedWebsites;
+
+
+//@description Contains information about the availability of the "Report spam" action for a chat @can_report_spam True, if a prompt with the "Report spam" action should be shown to the user
+chatReportSpamState can_report_spam:Bool = ChatReportSpamState;
+
+//@class ChatReportReason @description Describes the reason why a chat is reported
+
+//@description The chat contains spam messages
+chatReportReasonSpam = ChatReportReason;
+
+//@description The chat promotes violence
+chatReportReasonViolence = ChatReportReason;
+
+//@description The chat contains pornographic messages
+chatReportReasonPornography = ChatReportReason;
+
+//@description A custom reason provided by the user @text Report text
+chatReportReasonCustom text:string = ChatReportReason;
+
+
+//@description Contains a public HTTPS link to a message in a public supergroup or channel @link Message link @html HTML-code for embedding the message
+publicMessageLink link:string html:string = PublicMessageLink;
+
+
+//@class FileType @description Represents the type of a file
+
+//@description The data is not a file
+fileTypeNone = FileType;
+
+//@description The file is an animation
+fileTypeAnimation = FileType;
+
+//@description The file is an audio file
+fileTypeAudio = FileType;
+
+//@description The file is a document
+fileTypeDocument = FileType;
+
+//@description The file is a photo
+fileTypePhoto = FileType;
+
+//@description The file is a profile photo
+fileTypeProfilePhoto = FileType;
+
+//@description The file was sent to a secret chat (the file type is not known to the server)
+fileTypeSecret = FileType;
+
+//@description The file is a sticker
+fileTypeSticker = FileType;
+
+//@description The file is a thumbnail of another file
+fileTypeThumbnail = FileType;
+
+//@description The file type is not yet known
+fileTypeUnknown = FileType;
+
+//@description The file is a video
+fileTypeVideo = FileType;
+
+//@description The file is a video note
+fileTypeVideoNote = FileType;
+
+//@description The file is a voice note
+fileTypeVoiceNote = FileType;
+
+//@description The file is a wallpaper
+fileTypeWallpaper = FileType;
+
+//@description The file is a thumbnail of a file from a secret chat
+fileTypeSecretThumbnail = FileType;
+
+
+//@description Contains the storage usage statistics for a specific file type @file_type File type @size Total size of the files @count Total number of files
+storageStatisticsByFileType file_type:FileType size:int53 count:int32 = StorageStatisticsByFileType;
+
+//@description Contains the storage usage statistics for a specific chat @chat_id Chat identifier; 0 if none @size Total size of the files in the chat @count Total number of files in the chat @by_file_type Statistics split by file types
+storageStatisticsByChat chat_id:int53 size:int53 count:int32 by_file_type:vector<storageStatisticsByFileType> = StorageStatisticsByChat;
+
+//@description Contains the exact storage usage statistics split by chats and file type @size Total size of files @count Total number of files @by_chat Statistics split by chats
+storageStatistics size:int53 count:int32 by_chat:vector<storageStatisticsByChat> = StorageStatistics;
+
+//@description Contains approximate storage usage statistics, excluding files of unknown file type @files_size Approximate total size of files @file_count Approximate number of files @database_size Size of the database
+storageStatisticsFast files_size:int53 file_count:int32 database_size:int53 = StorageStatisticsFast;
+
+
+//@class NetworkType @description Represents the type of a network
+
+//@description The network is not available
+networkTypeNone = NetworkType;
+
+//@description A mobile network
+networkTypeMobile = NetworkType;
+
+//@description A mobile roaming network
+networkTypeMobileRoaming = NetworkType;
+
+//@description A Wi-Fi network
+networkTypeWiFi = NetworkType;
+
+//@description A different network type (e.g., Ethernet network)
+networkTypeOther = NetworkType;
+
+
+//@class NetworkStatisticsEntry @description Contains statistics about network usage
+
+//@description Contains information about the total amount of data that was used to send and receive files @file_type Type of the file the data is part of @network_type Type of the network the data was sent through. Call setNetworkType to maintain the actual network type
+//@sent_bytes Total number of bytes sent @received_bytes Total number of bytes received
+networkStatisticsEntryFile file_type:FileType network_type:NetworkType sent_bytes:int53 received_bytes:int53 = NetworkStatisticsEntry;
+
+//@description Contains information about the total amount of data that was used for calls @network_type Type of the network the data was sent through. Call setNetworkType to maintain the actual network type
+//@sent_bytes Total number of bytes sent @received_bytes Total number of bytes received @duration Total call duration, in seconds
+networkStatisticsEntryCall network_type:NetworkType sent_bytes:int53 received_bytes:int53 duration:double = NetworkStatisticsEntry;
+
+//@description A full list of available network statistic entries @since_date Point in time (Unix timestamp) when the app began collecting statistics @entries Network statistics entries
+networkStatistics since_date:int32 entries:vector<NetworkStatisticsEntry> = NetworkStatistics;
+
+
+//@class ConnectionState @description Describes the current state of the connection to Telegram servers
+
+//@description Currently waiting for the network to become available. Use SetNetworkType to change the available network type
+connectionStateWaitingForNetwork = ConnectionState;
+
+//@description Currently establishing a connection with a proxy server
+connectionStateConnectingToProxy = ConnectionState;
+
+//@description Currently establishing a connection to the Telegram servers
+connectionStateConnecting = ConnectionState;
+
+//@description Downloading data received while the client was offline
+connectionStateUpdating = ConnectionState;
+
+//@description There is a working connection to the Telegram servers
+connectionStateReady = ConnectionState;
+
+
+//@class TopChatCategory @description Represents the categories of chats for which a list of frequently used chats can be retrieved
+
+//@description A category containing frequently used private chats with non-bot users
+topChatCategoryUsers = TopChatCategory;
+
+//@description A category containing frequently used private chats with bot users
+topChatCategoryBots = TopChatCategory;
+
+//@description A category containing frequently used basic groups and supergroups
+topChatCategoryGroups = TopChatCategory;
+
+//@description A category containing frequently used channels
+topChatCategoryChannels = TopChatCategory;
+
+//@description A category containing frequently used chats with inline bots sorted by their usage in inline mode
+topChatCategoryInlineBots = TopChatCategory;
+
+//@description A category containing frequently used chats used for calls
+topChatCategoryCalls = TopChatCategory;
+
+
+//@class TMeUrlType @description Describes the type of a URL linking to an internal Telegram entity
+
+//@description A URL linking to a user @user_id Identifier of the user
+tMeUrlTypeUser user_id:int32 = TMeUrlType;
+
+//@description A URL linking to a public supergroup or channel @supergroup_id Identifier of the supergroup or channel
+tMeUrlTypeSupergroup supergroup_id:int53 = TMeUrlType;
+
+//@description A chat invite link @info Chat invite link info
+tMeUrlTypeChatInvite info:chatInviteLinkInfo = TMeUrlType;
+
+//@description A URL linking to a sticker set @sticker_set_id Identifier of the sticker set
+tMeUrlTypeStickerSet sticker_set_id:int64 = TMeUrlType;
+
+//@description Represents a URL linking to an internal Telegram entity @url URL @type Type of the URL
+tMeUrl url:string type:TMeUrlType = TMeUrl;
+
+//@description Contains a list of t.me URLs @urls List of URLs
+tMeUrls urls:vector<tMeUrl> = TMeUrls;
+
+
+//@description Contains a counter @count Count
+count count:int32 = Count;
+
+//@description Contains some text @text Text
+text text:string = Text;
+
+
+//@class TextParseMode @description Describes the way the text should be parsed for TextEntities
+
+//@description The text should be parsed in markdown-style
+textParseModeMarkdown = TextParseMode;
+
+//@description The text should be parsed in HTML-style
+textParseModeHTML = TextParseMode;
+
+
+//@class Proxy @description Contains information about a proxy server
+
+//@description An empty proxy server
+proxyEmpty = Proxy;
+
+//@description A SOCKS5 proxy server @server Proxy server IP address @port Proxy server port @username Username for logging in @password Password for logging in
+proxySocks5 server:string port:int32 username:string password:string = Proxy;
+
+
+//@description Describes a sticker that should be added to a sticker set @png_sticker PNG image with the sticker; must be up to 512 kB in size and fit in a 512x512 square @emojis Emoji corresponding to the sticker @mask_position For masks, position where the mask should be placed; may be null
+inputSticker png_sticker:InputFile emojis:string mask_position:maskPosition = InputSticker;
+
+
+//@class Update @description Contains notifications about data changes
+
+//@description The user authorization state has changed @authorization_state New authorization state
+updateAuthorizationState authorization_state:AuthorizationState = Update;
+
+//@description A new message was received; can also be an outgoing message @message The new message @disable_notification True, if this message must not generate a notification @contains_mention True, if the message contains a mention of the current user
+updateNewMessage message:message disable_notification:Bool contains_mention:Bool = Update;
+
+//@description A request to send a message has reached the Telegram server. This doesn't mean that the message will be sent successfully or even that the send message request will be processed. This update will be sent only if the option "use_quick_ack" is set to true. This update may be sent multiple times for the same message
+//@chat_id The chat identifier of the sent message @message_id A temporary message identifier
+updateMessageSendAcknowledged chat_id:int53 message_id:int53 = Update;
+
+//@description A message has been successfully sent @message Information about the sent message. Usually only the message identifier, date, and content are changed, but almost all other fields can also change @old_message_id The previous temporary message identifier
+updateMessageSendSucceeded message:message old_message_id:int53 = Update;
+
+//@description A message failed to send. Be aware that some messages being sent can be irrecoverably deleted, in which case updateDeleteMessages will be received instead of this update
+//@message Contains information about the message that failed to send @old_message_id The previous temporary message identifier @error_code An error code @error_message Error message
+updateMessageSendFailed message:message old_message_id:int53 error_code:int32 error_message:string = Update;
+
+//@description The message content has changed @chat_id Chat identifier @message_id Message identifier @new_content New message content
+updateMessageContent chat_id:int53 message_id:int53 new_content:MessageContent = Update;
+
+//@description A message was edited. Changes in the message content will come in a separate updateMessageContent @chat_id Chat identifier @message_id Message identifier @edit_date Point in time (Unix timestamp) when the message was edited @reply_markup New message reply markup; may be null
+updateMessageEdited chat_id:int53 message_id:int53 edit_date:int32 reply_markup:ReplyMarkup = Update;
+
+//@description The view count of the message has changed @chat_id Chat identifier @message_id Message identifier @views New value of the view count
+updateMessageViews chat_id:int53 message_id:int53 views:int32 = Update;
+
+//@description The message content was opened. Updates voice note messages to "listened", video note messages to "viewed" and starts the TTL timer for self-destructing messages @chat_id Chat identifier @message_id Message identifier
+updateMessageContentOpened chat_id:int53 message_id:int53 = Update;
+
+//@description A message with an unread mention was read @chat_id Chat identifier @message_id Message identifier @unread_mention_count The new number of unread mention messages left in the chat
+updateMessageMentionRead chat_id:int53 message_id:int53 unread_mention_count:int32 = Update;
+
+//@description A new chat has been loaded/created. This update is guaranteed to come before the chat identifier is returned to the client. The chat field changes will be reported through separate updates @chat The chat
+updateNewChat chat:chat = Update;
+
+//@description The title of a chat was changed @chat_id Chat identifier @title The new chat title
+updateChatTitle chat_id:int53 title:string = Update;
+
+//@description A chat photo was changed @chat_id Chat identifier @photo The new chat photo; may be null
+updateChatPhoto chat_id:int53 photo:chatPhoto = Update;
+
+//@description The last message of a chat was changed. If last_message is null then the last message in the chat became unknown. Some new unknown messages might be added to the chat in this case @chat_id Chat identifier @last_message The new last message in the chat; may be null @order New value of the chat order
+updateChatLastMessage chat_id:int53 last_message:message order:int64 = Update;
+
+//@description The order of the chat in the chats list has changed. Instead of this update updateChatLastMessage, updateChatIsPinned or updateChatDraftMessage might be sent @chat_id Chat identifier @order New value of the order
+updateChatOrder chat_id:int53 order:int64 = Update;
+
+//@description A chat was pinned or unpinned @chat_id Chat identifier @is_pinned New value of is_pinned @order New value of the chat order
+updateChatIsPinned chat_id:int53 is_pinned:Bool order:int64 = Update;
+
+//@description Incoming messages were read or number of unread messages has been changed @chat_id Chat identifier @last_read_inbox_message_id Identifier of the last read incoming message @unread_count The number of unread messages left in the chat
+updateChatReadInbox chat_id:int53 last_read_inbox_message_id:int53 unread_count:int32 = Update;
+
+//@description Outgoing messages were read @chat_id Chat identifier @last_read_outbox_message_id Identifier of last read outgoing message
+updateChatReadOutbox chat_id:int53 last_read_outbox_message_id:int53 = Update;
+
+//@description The chat unread_mention_count has changed @chat_id Chat identifier @unread_mention_count The number of unread mention messages left in the chat
+updateChatUnreadMentionCount chat_id:int53 unread_mention_count:int32 = Update;
+
+//@description Notification settings for some chats were updated @scope Types of chats for which notification settings were updated @notification_settings The new notification settings
+updateNotificationSettings scope:NotificationSettingsScope notification_settings:notificationSettings = Update;
+
+//@description The default chat reply markup was changed. Can occur because new messages with reply markup were received or because an old reply markup was hidden by the user
+//@chat_id Chat identifier @reply_markup_message_id Identifier of the message from which reply markup needs to be used; 0 if there is no default custom reply markup in the chat
+updateChatReplyMarkup chat_id:int53 reply_markup_message_id:int53 = Update;
+
+//@description A draft has changed. Be aware that the update may come in the currently opened chat but with old content of the draft. If the user has changed the content of the draft, this update shouldn't be applied @chat_id Chat identifier @draft_message The new draft message; may be null @order New value of the chat order
+updateChatDraftMessage chat_id:int53 draft_message:draftMessage order:int64 = Update;
+
+//@description Some messages were deleted @chat_id Chat identifier @message_ids Identifiers of the deleted messages
+//@is_permanent True, if the messages are permanently deleted by a user (as opposed to just becoming unaccessible)
+//@from_cache True, if the messages are deleted only from the cache and can possibly be retrieved again in the future
+updateDeleteMessages chat_id:int53 message_ids:vector<int53> is_permanent:Bool from_cache:Bool = Update;
+
+//@description User activity in the chat has changed @chat_id Chat identifier @user_id Identifier of a user performing an action @action The action description
+updateUserChatAction chat_id:int53 user_id:int32 action:ChatAction = Update;
+
+//@description The user went online or offline @user_id User identifier @status New status of the user
+updateUserStatus user_id:int32 status:UserStatus = Update;
+
+//@description Some data of a user has changed. This update is guaranteed to come before the user identifier is returned to the client @user New data about the user
+updateUser user:user = Update;
+
+//@description Some data of a basic group has changed. This update is guaranteed to come before the basic group identifier is returned to the client @basic_group New data about the group
+updateBasicGroup basic_group:basicGroup = Update;
+
+//@description Some data of a supergroup or a channel has changed. This update is guaranteed to come before the supergroup identifier is returned to the client @supergroup New data about the supergroup
+updateSupergroup supergroup:supergroup = Update;
+
+//@description Some data of a secret chat has changed. This update is guaranteed to come before the secret chat identifier is returned to the client @secret_chat New data about the secret chat
+updateSecretChat secret_chat:secretChat = Update;
+
+//@description Some data from userFullInfo has been changed @user_id User identifier @user_full_info New full information about the user
+updateUserFullInfo user_id:int32 user_full_info:userFullInfo = Update;
+
+//@description Some data from basicGroupFullInfo has been changed @basic_group_id Identifier of a basic group @basic_group_full_info New full information about the group
+updateBasicGroupFullInfo basic_group_id:int32 basic_group_full_info:basicGroupFullInfo = Update;
+
+//@description Some data from supergroupFullInfo has been changed @supergroup_id Identifier of the supergroup or channel @supergroup_full_info New full information about the supergroup
+updateSupergroupFullInfo supergroup_id:int32 supergroup_full_info:supergroupFullInfo = Update;
+
+//@description Service notification from the server. Upon receiving this the client must show a popup with the content of the notification @type Notification type @content Notification content
+updateServiceNotification type:string content:MessageContent = Update;
+
+//@description Information about a file was updated @file New data about the file
+updateFile file:file = Update;
+
+//@description The file generation process needs to be started by the client
+//@generation_id Unique identifier for the generation process
+//@original_path The path to a file from which a new file is generated, may be empty
+//@destination_path The path to a file that should be created and where the new file should be generated
+//@conversion String specifying the conversion applied to the original file. If conversion is "#url#" than original_path contains a HTTP/HTTPS URL of a file, which should be downloaded by the client
+updateFileGenerationStart generation_id:int64 original_path:string destination_path:string conversion:string = Update;
+
+//@description File generation is no longer needed @generation_id Unique identifier for the generation process
+updateFileGenerationStop generation_id:int64 = Update;
+
+//@description New call was created or information about a call was updated @call New data about a call
+updateCall call:call = Update;
+
+//@description Some privacy setting rules have been changed @setting The privacy setting @rules New privacy rules
+updateUserPrivacySettingRules setting:UserPrivacySetting rules:userPrivacySettingRules = Update;
+
+//@description Number of unread messages has changed. This update is sent only if a message database is used @unread_count Total number of unread messages @unread_unmuted_count Total number of unread messages in unmuted chats
+updateUnreadMessageCount unread_count:int32 unread_unmuted_count:int32 = Update;
+
+//@description An option changed its value @name The option name @value The new option value
+updateOption name:string value:OptionValue = Update;
+
+//@description The list of installed sticker sets was updated @is_masks True, if the list of installed mask sticker sets was updated @sticker_set_ids The new list of installed ordinary sticker sets
+updateInstalledStickerSets is_masks:Bool sticker_set_ids:vector<int64> = Update;
+
+//@description The list of trending sticker sets was updated or some of them were viewed @sticker_sets The new list of trending sticker sets
+updateTrendingStickerSets sticker_sets:stickerSets = Update;
+
+//@description The list of recently used stickers was updated @is_attached True, if the list of stickers attached to photo or video files was updated, otherwise the list of sent stickers is updated @sticker_ids The new list of file identifiers of recently used stickers
+updateRecentStickers is_attached:Bool sticker_ids:vector<int32> = Update;
+
+//@description The list of favorite stickers was updated @sticker_ids The new list of file identifiers of favorite stickers
+updateFavoriteStickers sticker_ids:vector<int32> = Update;
+
+//@description The list of saved animations was updated @animation_ids The new list of file identifiers of saved animations
+updateSavedAnimations animation_ids:vector<int32> = Update;
+
+//@description The connection state has changed @state The new connection state
+updateConnectionState state:ConnectionState = Update;
+
+//@description A new incoming inline query; for bots only @id Unique query identifier @sender_user_id Identifier of the user who sent the query @user_location User location, provided by the client; may be null @query Text of the query @offset Offset of the first entry to return
+updateNewInlineQuery id:int64 sender_user_id:int32 user_location:location query:string offset:string = Update;
+
+//@description The user has chosen a result of an inline query; for bots only @sender_user_id Identifier of the user who sent the query @user_location User location, provided by the client; may be null @query Text of the query @result_id Identifier of the chosen result @inline_message_id Identifier of the sent inline message, if known
+updateNewChosenInlineResult sender_user_id:int32 user_location:location query:string result_id:string inline_message_id:string = Update;
+
+//@description A new incoming callback query; for bots only @id Unique query identifier @sender_user_id Identifier of the user who sent the query @chat_id Identifier of the chat, in which the query was sent
+//@message_id Identifier of the message, from which the query originated @chat_instance Identifier that uniquely corresponds to the chat to which the message was sent @payload Query payload
+updateNewCallbackQuery id:int64 sender_user_id:int32 chat_id:int53 message_id:int53 chat_instance:int64 payload:CallbackQueryPayload = Update;
+
+//@description A new incoming callback query from a message sent via a bot; for bots only @id Unique query identifier @sender_user_id Identifier of the user who sent the query @inline_message_id Identifier of the inline message, from which the query originated
+//@chat_instance An identifier uniquely corresponding to the chat a message was sent to @payload Query payload
+updateNewInlineCallbackQuery id:int64 sender_user_id:int32 inline_message_id:string chat_instance:int64 payload:CallbackQueryPayload = Update;
+
+//@description A new incoming shipping query; for bots only. Only for invoices with flexible price @id Unique query identifier @sender_user_id Identifier of the user who sent the query @invoice_payload Invoice payload @shipping_address User shipping address
+updateNewShippingQuery id:int64 sender_user_id:int32 invoice_payload:string shipping_address:shippingAddress = Update;
+
+//@description A new incoming pre-checkout query; for bots only. Contains full information about a checkout @id Unique query identifier @sender_user_id Identifier of the user who sent the query @currency Currency for the product price @total_amount Total price for the product, in the minimal quantity of the currency
+//@invoice_payload Invoice payload @shipping_option_id Identifier of a shipping option chosen by the user; may be empty if not applicable @order_info Information about the order; may be null
+updateNewPreCheckoutQuery id:int64 sender_user_id:int32 currency:string total_amount:int53 invoice_payload:bytes shipping_option_id:string order_info:orderInfo = Update;
+
+//@description A new incoming event; for bots only @event A JSON-serialized event
+updateNewCustomEvent event:string = Update;
+
+//@description A new incoming query; for bots only @id The query identifier @data JSON-serialized query data @timeout Query timeout
+updateNewCustomQuery id:int64 data:string timeout:int32 = Update;
+
+
+//@description A simple object containing a number; for testing only @value Number
+testInt value:int32 = TestInt;
+//@description A simple object containing a string; for testing only @value String
+testString value:string = TestString;
+//@description A simple object containing a sequence of bytes; for testing only @value Bytes
+testBytes value:bytes = TestBytes;
+//@description A simple object containing a vector of numbers; for testing only @value Vector of numbers
+testVectorInt value:vector<int32> = TestVectorInt;
+//@description A simple object containing a vector of objects that hold a number; for testing only @value Vector of objects
+testVectorIntObject value:vector<testInt> = TestVectorIntObject;
+//@description A simple object containing a vector of strings; for testing only @value Vector of strings
+testVectorString value:vector<string> = TestVectorString;
+//@description A simple object containing a vector of objects that hold a string; for testing only @value Vector of objects
+testVectorStringObject value:vector<testString> = TestVectorStringObject;
+
+---functions---
+
+//@description Returns the current authorization state; this is an offline request. For informational purposes only. Use updateAuthorizationState instead to maintain the current authorization state
+getAuthorizationState = AuthorizationState;
+
+
+//@description Sets the parameters for TDLib initialization. Works only when the current authorization state is authorizationStateWaitTdlibParameters @parameters Parameters
+setTdlibParameters parameters:tdlibParameters = Ok;
+
+//@description Checks the database encryption key for correctness. Works only when the current authorization state is authorizationStateWaitEncryptionKey @encryption_key Encryption key to check or set up
+checkDatabaseEncryptionKey encryption_key:bytes = Ok;
+
+//@description Sets the phone number of the user and sends an authentication code to the user. Works only when the current authorization state is authorizationStateWaitPhoneNumber
+//@phone_number The phone number of the user, in international format @allow_flash_call Pass true if the authentication code may be sent via flash call to the specified phone number @is_current_phone_number Pass true if the phone number is used on the current device. Ignored if allow_flash_call is false
+setAuthenticationPhoneNumber phone_number:string allow_flash_call:Bool is_current_phone_number:Bool = Ok;
+
+//@description Re-sends an authentication code to the user. Works only when the current authorization state is authorizationStateWaitCode and the next_code_type of the result is not null
+resendAuthenticationCode = Ok;
+
+//@description Checks the authentication code. Works only when the current authorization state is authorizationStateWaitCode @code The verification code received via SMS, Telegram message, phone call, or flash call
+//@first_name If the user is not yet registered, the first name of the user; 1-255 characters @last_name If the user is not yet registered; the last name of the user; optional; 0-255 characters
+checkAuthenticationCode code:string first_name:string last_name:string = Ok;
+
+//@description Checks the authentication password for correctness. Works only when the current authorization state is authorizationStateWaitPassword @password The password to check
+checkAuthenticationPassword password:string = Ok;
+
+//@description Requests to send a password recovery code to an email address that was previously set up. Works only when the current authorization state is authorizationStateWaitPassword
+requestAuthenticationPasswordRecovery = Ok;
+
+//@description Recovers the password with a password recovery code sent to an email address that was previously set up. Works only when the current authorization state is authorizationStateWaitPassword @recovery_code Recovery code to check
+recoverAuthenticationPassword recovery_code:string = Ok;
+
+//@description Checks the authentication token of a bot; to log in as a bot. Works only when the current authorization state is authorizationStateWaitPhoneNumber. Can be used instead of setAuthenticationPhoneNumber and checkAuthenticationCode to log in @token The bot token
+checkAuthenticationBotToken token:string = Ok;
+
+//@description Closes the TDLib instance after a proper logout. Requires an available network connection. All local data will be destroyed. After the logout completes, updateAuthorizationState with authorizationStateClosed will be sent
+logOut = Ok;
+
+//@description Closes the TDLib instance. All databases will be flushed to disk and properly closed. After the close completes, updateAuthorizationState with authorizationStateClosed will be sent
+close = Ok;
+
+//@description Closes the TDLib instance, destroying all local data without a proper logout. The current user session will remain in the list of all active sessions. All local data will be destroyed. After the destruction completes updateAuthorizationState with authorizationStateClosed will be sent
+destroy = Ok;
+
+
+//@description Changes the database encryption key. Usually the encryption key is never changed and is stored in some OS keychain @new_encryption_key New encryption key
+setDatabaseEncryptionKey new_encryption_key:bytes = Ok;
+
+
+//@description Returns the current state of 2-step verification
+getPasswordState = PasswordState;
+
+//@description Changes the password for the user. If a new recovery email address is specified, then the error EMAIL_UNCONFIRMED is returned and the password change will not be applied until the new recovery email address has been confirmed. The application should periodically call getPasswordState to check whether the new email address has been confirmed
+//@old_password Previous password of the user @new_password New password of the user; may be empty to remove the password @new_hint New password hint; may be empty @set_recovery_email_address Pass true if the recovery email address should be changed @new_recovery_email_address New recovery email address; may be empty
+setPassword old_password:string new_password:string new_hint:string set_recovery_email_address:Bool new_recovery_email_address:string = PasswordState;
+
+//@description Returns a recovery email address that was previously set up. This method can be used to verify a password provided by the user @password The password for the current user
+getRecoveryEmailAddress password:string = RecoveryEmailAddress;
+
+//@description Changes the recovery email address of the user. If a new recovery email address is specified, then the error EMAIL_UNCONFIRMED is returned and the email address will not be changed until the new email has been confirmed. The application should periodically call getPasswordState to check whether the email address has been confirmed.
+//-If new_recovery_email_address is the same as the email address that is currently set up, this call succeeds immediately and aborts all other requests waiting for an email confirmation @password Password of the current user @new_recovery_email_address New recovery email address
+setRecoveryEmailAddress password:string new_recovery_email_address:string = PasswordState;
+
+//@description Requests to send a password recovery code to an email address that was previously set up
+requestPasswordRecovery = PasswordRecoveryInfo;
+
+//@description Recovers the password using a recovery code sent to an email address that was previously set up @recovery_code Recovery code to check
+recoverPassword recovery_code:string = PasswordState;
+
+//@description Creates a new temporary password for processing payments @password Persistent user password @valid_for Time during which the temporary password will be valid, in seconds; should be between 60 and 86400
+createTemporaryPassword password:string valid_for:int32 = TemporaryPasswordState;
+
+//@description Returns information about the current temporary password
+getTemporaryPasswordState = TemporaryPasswordState;
+
+
+//@description Handles a DC_UPDATE push service notification. Can be called before authorization @dc Value of the "dc" parameter of the notification @addr Value of the "addr" parameter of the notification
+processDcUpdate dc:string addr:string = Ok;
+
+
+//@description Returns the current user
+getMe = User;
+
+//@description Returns information about a user by their identifier. This is an offline request if the current user is not a bot @user_id User identifier
+getUser user_id:int32 = User;
+
+//@description Returns full information about a user by their identifier @user_id User identifier
+getUserFullInfo user_id:int32 = UserFullInfo;
+
+//@description Returns information about a basic group by its identifier. This is an offline request if the current user is not a bot @basic_group_id Basic group identifier
+getBasicGroup basic_group_id:int32 = BasicGroup;
+
+//@description Returns full information about a basic group by its identifier @basic_group_id Basic group identifier
+getBasicGroupFullInfo basic_group_id:int32 = BasicGroupFullInfo;
+
+//@description Returns information about a supergroup or channel by its identifier. This is an offline request if the current user is not a bot @supergroup_id Supergroup or channel identifier
+getSupergroup supergroup_id:int32 = Supergroup;
+
+//@description Returns full information about a supergroup or channel by its identifier, cached for up to 1 minute @supergroup_id Supergroup or channel identifier
+getSupergroupFullInfo supergroup_id:int32 = SupergroupFullInfo;
+
+//@description Returns information about a secret chat by its identifier. This is an offline request @secret_chat_id Secret chat identifier
+getSecretChat secret_chat_id:int32 = SecretChat;
+
+//@description Returns information about a chat by its identifier, this is an offline request if the current user is not a bot @chat_id Chat identifier
+getChat chat_id:int53 = Chat;
+
+//@description Returns information about a message @chat_id Identifier of the chat the message belongs to @message_id Identifier of the message to get
+getMessage chat_id:int53 message_id:int53 = Message;
+
+//@description Returns information about a message that is replied by given message @chat_id Identifier of the chat the message belongs to @message_id Identifier of the message reply to which get
+getRepliedMessage chat_id:int53 message_id:int53 = Message;
+
+//@description Returns information about a pinned chat message @chat_id Identifier of the chat the message belongs to
+getChatPinnedMessage chat_id:int53 = Message;
+
+//@description Returns information about messages. If a message is not found, returns null on the corresponding position of the result @chat_id Identifier of the chat the messages belong to @message_ids Identifiers of the messages to get
+getMessages chat_id:int53 message_ids:vector<int53> = Messages;
+
+//@description Returns information about a file; this is an offline request @file_id Identifier of the file to get
+getFile file_id:int32 = File;
+
+//@description Returns information about a file by its remote ID; this is an offline request. Can be used to register a URL as a file for further uploading, or sending as a message @remote_file_id Remote identifier of the file to get @file_type File type, if known
+getRemoteFile remote_file_id:string file_type:FileType = File;
+
+//@description Returns an ordered list of chats. Chats are sorted by the pair (order, chat_id) in decreasing order. (For example, to get a list of chats from the beginning, the offset_order should be equal to 2^63 - 1).
+//-For optimal performance the number of returned chats is chosen by the library. @offset_order Chat order to return chats from @offset_chat_id Chat identifier to return chats from
+//@limit The maximum number of chats to be returned. It is possible that fewer chats than the limit are returned even if the end of the list is not reached
+getChats offset_order:int64 offset_chat_id:int53 limit:int32 = Chats;
+
+//@description Searches a public chat by its username. Currently only private chats, supergroups and channels can be public. Returns the chat if found; otherwise an error is returned @username Username to be resolved
+searchPublicChat username:string = Chat;
+
+//@description Searches public chats by looking for specified query in their username and title. Currently only private chats, supergroups and channels can be public. Returns a meaningful number of results. Returns nothing if the length of the searched username prefix is less than 5. Excludes private chats with contacts and chats from the chat list from the results @query Query to search for
+searchPublicChats query:string = Chats;
+
+//@description Searches for the specified query in the title and username of already known chats, this is an offline request. Returns chats in the order seen in the chat list @query Query to search for. If the query is empty, returns up to 20 recently found chats @limit Maximum number of chats to be returned
+searchChats query:string limit:int32 = Chats;
+
+//@description Searches for the specified query in the title and username of already known chats via request to the server. Returns chats in the order seen in the chat list @query Query to search for @limit Maximum number of chats to be returned
+searchChatsOnServer query:string limit:int32 = Chats;
+
+//@description Returns a list of frequently used chats. Supported only if the chat info database is enabled @category Category of chats to be returned @limit Maximum number of chats to be returned; up to 30
+getTopChats category:TopChatCategory limit:int32 = Chats;
+
+//@description Removes a chat from the list of frequently used chats. Supported only if the chat info database is enabled @category Category of frequently used chats @chat_id Chat identifier
+removeTopChat category:TopChatCategory chat_id:int53 = Ok;
+
+//@description Adds a chat to the list of recently found chats. The chat is added to the beginning of the list. If the chat is already in the list, it will be removed from the list first @chat_id Identifier of the chat to add
+addRecentlyFoundChat chat_id:int53 = Ok;
+
+//@description Removes a chat from the list of recently found chats @chat_id Identifier of the chat to be removed
+removeRecentlyFoundChat chat_id:int53 = Ok;
+
+//@description Clears the list of recently found chats
+clearRecentlyFoundChats = Ok;
+
+//@description Checks whether a username can be set for a chat @chat_id Chat identifier; should be identifier of a supergroup chat, or a channel chat, or a private chat with self, or zero if chat is being created @username Username to be checked
+checkChatUsername chat_id:int64 username:string = CheckChatUsernameResult;
+
+//@description Returns a list of public chats created by the user
+getCreatedPublicChats = Chats;
+
+
+//@description Returns a list of common chats with a given user. Chats are sorted by their type and creation date @user_id User identifier @offset_chat_id Chat identifier starting from which to return chats; use 0 for the first request @limit Maximum number of chats to be returned; up to 100
+getGroupsInCommon user_id:int32 offset_chat_id:int53 limit:int32 = Chats;
+
+
+//@description Returns messages in a chat. The messages are returned in a reverse chronological order (i.e., in order of decreasing message_id).
+//-For optimal performance the number of returned messages is chosen by the library. This is an offline request if only_local is true
+//@chat_id Chat identifier
+//@from_message_id Identifier of the message starting from which history must be fetched; use 0 to get results from the beginning (i.e., from oldest to newest)
+//@offset Specify 0 to get results from exactly the from_message_id or a negative offset to get the specified message and some newer messages
+//@limit The maximum number of messages to be returned; must be positive and can't be greater than 100. If the offset is negative, the limit must be greater than -offset. Fewer messages may be returned than specified by the limit, even if the end of the message history has not been reached
+//@only_local If true, returns only messages that are available locally without sending network requests
+getChatHistory chat_id:int53 from_message_id:int53 offset:int32 limit:int32 only_local:Bool = Messages;
+
+//@description Deletes all messages in the chat only for the user. Cannot be used in channels and public supergroups @chat_id Chat identifier @remove_from_chat_list Pass true if the chat should be removed from the chats list
+deleteChatHistory chat_id:int53 remove_from_chat_list:Bool = Ok;
+
+//@description Searches for messages with given words in the chat. Returns the results in reverse chronological order, i.e. in order of decreasing message_id. Cannot be used in secret chats with a non-empty query
+//-(searchSecretMessages should be used instead), or without an enabled message database. For optimal performance the number of returned messages is chosen by the library
+//@chat_id Identifier of the chat in which to search messages
+//@query Query to search for
+//@sender_user_id If not 0, only messages sent by the specified user will be returned. Not supported in secret chats
+//@from_message_id Identifier of the message starting from which history must be fetched; use 0 to get results from the beginning
+//@offset Specify 0 to get results from exactly the from_message_id or a negative offset to get the specified message and some newer messages
+//@limit The maximum number of messages to be returned; must be positive and can't be greater than 100. If the offset is negative, the limit must be greater than -offset. Fewer messages may be returned than specified by the limit, even if the end of the message history has not been reached
+//@filter Filter for message content in the search results
+searchChatMessages chat_id:int53 query:string sender_user_id:int32 from_message_id:int53 offset:int32 limit:int32 filter:SearchMessagesFilter = Messages;
+
+//@description Searches for messages in all chats except secret chats. Returns the results in reverse chronological order (i.e., in order of decreasing (date, chat_id, message_id)).
+//-For optimal performance the number of returned messages is chosen by the library
+//@query Query to search for
+//@offset_date The date of the message starting from which the results should be fetched. Use 0 or any date in the future to get results from the beginning
+//@offset_chat_id The chat identifier of the last found message, or 0 for the first request
+//@offset_message_id The message identifier of the last found message, or 0 for the first request
+//@limit The maximum number of messages to be returned, up to 100. Fewer messages may be returned than specified by the limit, even if the end of the message history has not been reached
+searchMessages query:string offset_date:int32 offset_chat_id:int53 offset_message_id:int53 limit:int32 = Messages;
+
+//@description Searches for messages in secret chats. Returns the results in reverse chronological order. For optimal performance the number of returned messages is chosen by the library
+//@chat_id Identifier of the chat in which to search. Specify 0 to search in all secret chats @query Query to search for. If empty, searchChatMessages should be used instead
+//@from_search_id The identifier from the result of a previous request, use 0 to get results from the beginning
+//@limit Maximum number of messages to be returned; up to 100. Fewer messages may be returned than specified by the limit, even if the end of the message history has not been reached
+//@filter A filter for the content of messages in the search results
+searchSecretMessages chat_id:int53 query:string from_search_id:int64 limit:int32 filter:SearchMessagesFilter = FoundMessages;
+
+//@description Searches for call messages. Returns the results in reverse chronological order (i. e., in order of decreasing message_id). For optimal performance the number of returned messages is chosen by the library
+//@from_message_id Identifier of the message from which to search; use 0 to get results from the beginning
+//@limit The maximum number of messages to be returned; up to 100. Fewer messages may be returned than specified by the limit, even if the end of the message history has not been reached @only_missed If true, returns only messages with missed calls
+searchCallMessages from_message_id:int53 limit:int32 only_missed:Bool = Messages;
+
+//@description Returns information about the recent locations of chat members that were sent to the chat. Returns up to 1 location message per user @chat_id Chat identifier @limit Maximum number of messages to be returned
+searchChatRecentLocationMessages chat_id:int53 limit:int32 = Messages;
+
+//@description Returns all active live locations that should be updated by the client. The list is persistent across application restarts only if the message database is used
+getActiveLiveLocationMessages = Messages;
+
+//@description Returns the last message sent in a chat no later than the specified date @chat_id Chat identifier @date Point in time (Unix timestamp) relative to which to search for messages
+getChatMessageByDate chat_id:int53 date:int32 = Message;
+
+
+//@description Returns a public HTTPS link to a message. Available only for messages in public supergroups and channels
+//@chat_id Identifier of the chat to which the message belongs
+//@message_id Identifier of the message
+//@for_album Pass true if a link for a whole media album should be returned
+getPublicMessageLink chat_id:int53 message_id:int53 for_album:Bool = PublicMessageLink;
+
+
+//@description Sends a message. Returns the sent message @chat_id Target chat @reply_to_message_id Identifier of the message to reply to or 0
+//@disable_notification Pass true to disable notification for the message. Not supported in secret chats @from_background Pass true if the message is sent from the background
+//@reply_markup Markup for replying to the message; for bots only @input_message_content The content of the message to be sent
+sendMessage chat_id:int53 reply_to_message_id:int53 disable_notification:Bool from_background:Bool reply_markup:ReplyMarkup input_message_content:InputMessageContent = Message;
+
+//@description Sends messages grouped together into an album. Currently only photo and video messages can be grouped into an album. Returns sent messages @chat_id Target chat @reply_to_message_id Identifier of a message to reply to or 0
+//@disable_notification Pass true to disable notification for the messages. Not supported in secret chats @from_background Pass true if the messages are sent from the background
+//@input_message_contents Contents of messages to be sent
+sendMessageAlbum chat_id:int53 reply_to_message_id:int53 disable_notification:Bool from_background:Bool input_message_contents:vector<InputMessageContent> = Messages;
+
+//@description Invites a bot to a chat (if it is not yet a member) and sends it the /start command. Bots can't be invited to a private chat other than the chat with the bot. Bots can't be invited to channels (although they can be added as admins) and secret chats. Returns the sent message
+//@bot_user_id Identifier of the bot @chat_id Identifier of the target chat @parameter A hidden parameter sent to the bot for deep linking purposes (https://api.telegram.org/bots#deep-linking)
+sendBotStartMessage bot_user_id:int32 chat_id:int53 parameter:string = Message;
+
+//@description Sends the result of an inline query as a message. Returns the sent message. Always clears a chat draft message @chat_id Target chat @reply_to_message_id Identifier of a message to reply to or 0
+//@disable_notification Pass true to disable notification for the message. Not supported in secret chats @from_background Pass true if the message is sent from background
+//@query_id Identifier of the inline query @result_id Identifier of the inline result
+sendInlineQueryResultMessage chat_id:int53 reply_to_message_id:int53 disable_notification:Bool from_background:Bool query_id:int64 result_id:string = Message;
+
+//@description Forwards previously sent messages. Returns the forwarded messages in the same order as the message identifiers passed in message_ids. If a message can't be forwarded, null will be returned instead of the message
+//@chat_id Identifier of the chat to which to forward messages @from_chat_id Identifier of the chat from which to forward messages @message_ids Identifiers of the messages to forward
+//@disable_notification Pass true to disable notification for the message, doesn't work if messages are forwarded to a secret chat @from_background Pass true if the message is sent from the background
+//@as_album True, if the messages should be grouped into an album after forwarding. For this to work, no more than 10 messages may be forwarded, and all of them must be photo or video messages
+forwardMessages chat_id:int53 from_chat_id:int53 message_ids:vector<int53> disable_notification:Bool from_background:Bool as_album:Bool = Messages;
+
+//@description Changes the current TTL setting (sets a new self-destruct timer) in a secret chat and sends the corresponding message @chat_id Chat identifier @ttl New TTL value, in seconds
+sendChatSetTtlMessage chat_id:int53 ttl:int32 = Message;
+
+//@description Sends a notification about a screenshot taken in a chat. Supported only in private and secret chats @chat_id Chat identifier
+sendChatScreenshotTakenNotification chat_id:int53 = Ok;
+
+//@description Deletes messages @chat_id Chat identifier @message_ids Identifiers of the messages to be deleted @revoke Pass true to try to delete outgoing messages for all chat members (may fail if messages are too old). Always true for supergroups, channels and secret chats
+deleteMessages chat_id:int53 message_ids:vector<int53> revoke:Bool = Ok;
+
+//@description Deletes all messages sent by the specified user to a chat. Supported only in supergroups; requires can_delete_messages administrator privileges @chat_id Chat identifier @user_id User identifier
+deleteChatMessagesFromUser chat_id:int53 user_id:int32 = Ok;
+
+
+//@description Edits the text of a message (or a text of a game message). Non-bot users can edit messages for a limited period of time. Returns the edited message after the edit is completed on the server side
+//@chat_id The chat the message belongs to @message_id Identifier of the message @reply_markup The new message reply markup; for bots only @input_message_content New text content of the message. Should be of type InputMessageText
+editMessageText chat_id:int53 message_id:int53 reply_markup:ReplyMarkup input_message_content:InputMessageContent = Message;
+
+//@description Edits the message content of a live location. Messages can be edited for a limited period of time specified in the live location. Returns the edited message after the edit is completed server-side
+//@chat_id The chat the message belongs to @message_id Identifier of the message @reply_markup Tew message reply markup; for bots only @location New location content of the message; may be null. Pass null to stop sharing the live location
+editMessageLiveLocation chat_id:int53 message_id:int53 reply_markup:ReplyMarkup location:location = Message;
+
+//@description Edits the message content caption. Non-bots can edit messages for a limited period of time. Returns the edited message after the edit is completed server-side
+//@chat_id The chat the message belongs to @message_id Identifier of the message @reply_markup The new message reply markup; for bots only @caption New message content caption; 0-200 characters
+editMessageCaption chat_id:int53 message_id:int53 reply_markup:ReplyMarkup caption:formattedText = Message;
+
+//@description Edits the message reply markup; for bots only. Returns the edited message after the edit is completed server-side
+//@chat_id The chat the message belongs to @message_id Identifier of the message @reply_markup New message reply markup
+editMessageReplyMarkup chat_id:int53 message_id:int53 reply_markup:ReplyMarkup = Message;
+
+//@description Edits the text of an inline text or game message sent via a bot; for bots only @inline_message_id Inline message identifier @reply_markup New message reply markup @input_message_content New text content of the message. Should be of type InputMessageText
+editInlineMessageText inline_message_id:string reply_markup:ReplyMarkup input_message_content:InputMessageContent = Ok;
+
+//@description Edits the content of a live location in an inline message sent via a bot; for bots only @inline_message_id Inline message identifier @reply_markup New message reply markup @location New location content of the message; may be null. Pass null to stop sharing the live location
+editInlineMessageLiveLocation inline_message_id:string reply_markup:ReplyMarkup location:location = Ok;
+
+//@description Edits the caption of an inline message sent via a bot; for bots only @inline_message_id Inline message identifier @reply_markup New message reply markup @caption New message content caption; 0-200 characters
+editInlineMessageCaption inline_message_id:string reply_markup:ReplyMarkup caption:formattedText = Ok;
+
+//@description Edits the reply markup of an inline message sent via a bot; for bots only @inline_message_id Inline message identifier @reply_markup New message reply markup
+editInlineMessageReplyMarkup inline_message_id:string reply_markup:ReplyMarkup = Ok;
+
+
+//@description Returns all entities (mentions, hashtags, cashtags, bot commands, URLs, and email addresses) contained in the text. This is an offline method. Can be called before authorization. Can be called synchronously @text The text in which to look for entites
+getTextEntities text:string = TextEntities;
+
+//@description Parses Bold, Italic, Code, Pre, PreCode and TextUrl entities contained in the text. This is an offline method. Can be called before authorization. Can be called synchronously @text The text which should be parsed @parse_mode Text parse mode
+parseTextEntities text:string parse_mode:TextParseMode = FormattedText;
+
+//@description Returns the MIME type of a file, guessed by its extension. Returns an empty string on failure. This is an offline method. Can be called before authorization. Can be called synchronously @file_name The name of the file or path to the file
+getFileMimeType file_name:string = Text;
+
+//@description Returns the extension of a file, guessed by its MIME type. Returns an empty string on failure. This is an offline method. Can be called before authorization. Can be called synchronously @mime_type The MIME type of the file
+getFileExtension mime_type:string = Text;
+
+
+//@description Sends an inline query to a bot and returns its results. Returns an error with code 502 if the bot fails to answer the query before the query timeout expires @bot_user_id The identifier of the target bot
+//@chat_id Identifier of the chat, where the query was sent @user_location Location of the user, only if needed @query Text of the query @offset Offset of the first entry to return
+getInlineQueryResults bot_user_id:int32 chat_id:int53 user_location:location query:string offset:string = InlineQueryResults;
+
+//@description Sets the result of an inline query; for bots only @inline_query_id Identifier of the inline query @is_personal True, if the result of the query can be cached for the specified user
+//@results The results of the query @cache_time Allowed time to cache the results of the query, in seconds @next_offset Offset for the next inline query; pass an empty string if there are no more results
+//@switch_pm_text If non-empty, this text should be shown on the button that opens a private chat with the bot and sends a start message to the bot with the parameter switch_pm_parameter @switch_pm_parameter The parameter for the bot start message
+answerInlineQuery inline_query_id:int64 is_personal:Bool results:vector<InputInlineQueryResult> cache_time:int32 next_offset:string switch_pm_text:string switch_pm_parameter:string = Ok;
+
+
+//@description Sends a callback query to a bot and returns an answer. Returns an error with code 502 if the bot fails to answer the query before the query timeout expires @chat_id Identifier of the chat with the message @message_id Identifier of the message from which the query originated @payload Query payload
+getCallbackQueryAnswer chat_id:int53 message_id:int53 payload:CallbackQueryPayload = CallbackQueryAnswer;
+
+//@description Sets the result of a callback query; for bots only @callback_query_id Identifier of the callback query @text Text of the answer @show_alert If true, an alert should be shown to the user instead of a toast notification @url URL to be opened @cache_time Time during which the result of the query can be cached, in seconds
+answerCallbackQuery callback_query_id:int64 text:string show_alert:Bool url:string cache_time:int32 = Ok;
+
+
+//@description Sets the result of a shipping query; for bots only @shipping_query_id Identifier of the shipping query @shipping_options Available shipping options @error_message An error message, empty on success
+answerShippingQuery shipping_query_id:int64 shipping_options:vector<shippingOption> error_message:string = Ok;
+
+//@description Sets the result of a pre-checkout query; for bots only @pre_checkout_query_id Identifier of the pre-checkout query @error_message An error message, empty on success
+answerPreCheckoutQuery pre_checkout_query_id:int64 error_message:string = Ok;
+
+
+//@description Updates the game score of the specified user in the game; for bots only @chat_id The chat to which the message with the game @message_id Identifier of the message @edit_message True, if the message should be edited @user_id User identifier @score The new score
+//@force Pass true to update the score even if it decreases. If the score is 0, the user will be deleted from the high score table
+setGameScore chat_id:int53 message_id:int53 edit_message:Bool user_id:int32 score:int32 force:Bool = Message;
+
+//@description Updates the game score of the specified user in a game; for bots only @inline_message_id Inline message identifier @edit_message True, if the message should be edited @user_id User identifier @score The new score
+//@force Pass true to update the score even if it decreases. If the score is 0, the user will be deleted from the high score table
+setInlineGameScore inline_message_id:string edit_message:Bool user_id:int32 score:int32 force:Bool = Ok;
+
+//@description Returns the high scores for a game and some part of the high score table in the range of the specified user; for bots only @chat_id The chat that contains the message with the game @message_id Identifier of the message @user_id User identifier
+getGameHighScores chat_id:int53 message_id:int53 user_id:int32 = GameHighScores;
+
+//@description Returns game high scores and some part of the high score table in the range of the specified user; for bots only @inline_message_id Inline message identifier @user_id User identifier
+getInlineGameHighScores inline_message_id:string user_id:int32 = GameHighScores;
+
+
+//@description Deletes the default reply markup from a chat. Must be called after a one-time keyboard or a ForceReply reply markup has been used. UpdateChatReplyMarkup will be sent if the reply markup will be changed @chat_id Chat identifier
+//@message_id The message identifier of the used keyboard
+deleteChatReplyMarkup chat_id:int53 message_id:int53 = Ok;
+
+
+//@description Sends a notification about user activity in a chat @chat_id Chat identifier @action The action description
+sendChatAction chat_id:int53 action:ChatAction = Ok;
+
+
+//@description This method should be called if the chat is opened by the user. Many useful activities depend on the chat being opened or closed (e.g., in supergroups and channels all updates are received only for opened chats) @chat_id Chat identifier
+openChat chat_id:int53 = Ok;
+
+//@description This method should be called if the chat is closed by the user. Many useful activities depend on the chat being opened or closed @chat_id Chat identifier
+closeChat chat_id:int53 = Ok;
+
+//@description This method should be called if messages are being viewed by the user. Many useful activities depend on whether the messages are currently being viewed or not (e.g., marking messages as read, incrementing a view counter, updating a view counter, removing deleted messages in supergroups and channels) @chat_id Chat identifier @message_ids The identifiers of the messages being viewed
+//@force_read True, if messages in closed chats should be marked as read
+viewMessages chat_id:int53 message_ids:vector<int53> force_read:Bool = Ok;
+
+//@description This method should be called if the message content has been opened (e.g., the user has opened a photo, video, document, location or venue, or has listened to an audio file or voice note message). An updateMessageContentOpened update will be generated if something has changed @chat_id Chat identifier of the message @message_id Identifier of the message with the opened content
+openMessageContent chat_id:int53 message_id:int53 = Ok;
+
+
+//@description Marks all mentions in a chat as read @chat_id Chat identifier
+readAllChatMentions chat_id:int53 = Ok;
+
+
+//@description Returns an existing chat corresponding to a given user @user_id User identifier @force If true, the chat will be created without network request. In this case all information about the chat except its type, title and photo can be incorrect
+createPrivateChat user_id:int32 force:Bool = Chat;
+
+//@description Returns an existing chat corresponding to a known basic group @basic_group_id Basic group identifier @force If true, the chat will be created without network request. In this case all information about the chat except its type, title and photo can be incorrect
+createBasicGroupChat basic_group_id:int32 force:Bool = Chat;
+
+//@description Returns an existing chat corresponding to a known supergroup or channel @supergroup_id Supergroup or channel identifier @force If true, the chat will be created without network request. In this case all information about the chat except its type, title and photo can be incorrect
+createSupergroupChat supergroup_id:int32 force:Bool = Chat;
+
+//@description Returns an existing chat corresponding to a known secret chat @secret_chat_id Secret chat identifier
+createSecretChat secret_chat_id:int32 = Chat;
+
+//@description Creates a new basic group and sends a corresponding messageBasicGroupChatCreate. Returns the newly created chat @user_ids Identifiers of users to be added to the basic group @title Title of the new basic group; 1-255 characters
+createNewBasicGroupChat user_ids:vector<int32> title:string = Chat;
+
+//@description Creates a new supergroup or channel and sends a corresponding messageSupergroupChatCreate. Returns the newly created chat @title Title of the new chat; 1-255 characters @is_channel True, if a channel chat should be created @param_description Chat description; 0-255 characters
+createNewSupergroupChat title:string is_channel:Bool description:string = Chat;
+
+//@description Creates a new secret chat. Returns the newly created chat @user_id Identifier of the target user
+createNewSecretChat user_id:int32 = Chat;
+
+//@description Creates a new supergroup from an existing basic group and sends a corresponding messageChatUpgradeTo and messageChatUpgradeFrom. Deactivates the original basic group @chat_id Identifier of the chat to upgrade
+upgradeBasicGroupChatToSupergroupChat chat_id:int53 = Chat;
+
+
+//@description Changes the chat title. Supported only for basic groups, supergroups and channels. Requires administrator rights in basic groups and the appropriate administrator rights in supergroups and channels. The title will not be changed until the request to the server has been completed
+//@chat_id Chat identifier @title New title of the chat; 1-255 characters
+setChatTitle chat_id:int53 title:string = Ok;
+
+//@description Changes the photo of a chat. Supported only for basic groups, supergroups and channels. Requires administrator rights in basic groups and the appropriate administrator rights in supergroups and channels. The photo will not be changed before request to the server has been completed
+//@chat_id Chat identifier @photo New chat photo. You can use a zero InputFileId to delete the chat photo. Files that are accessible only by HTTP URL are not acceptable
+setChatPhoto chat_id:int53 photo:InputFile = Ok;
+
+//@description Changes the draft message in a chat @chat_id Chat identifier @draft_message New draft message; may be null
+setChatDraftMessage chat_id:int53 draft_message:draftMessage = Ok;
+
+//@description Changes the pinned state of a chat. You can pin up to GetOption("pinned_chat_count_max") non-secret chats and the same number of secret chats @chat_id Chat identifier @is_pinned New value of is_pinned
+toggleChatIsPinned chat_id:int53 is_pinned:Bool = Ok;
+
+//@description Changes client data associated with a chat @chat_id Chat identifier @client_data New value of client_data
+setChatClientData chat_id:int53 client_data:string = Ok;
+
+//@description Adds a new member to a chat. Members can't be added to private or secret chats. Members will not be added until the chat state has been synchronized with the server
+//@chat_id Chat identifier @user_id Identifier of the user @forward_limit The number of earlier messages from the chat to be forwarded to the new member; up to 300. Ignored for supergroups and channels
+addChatMember chat_id:int53 user_id:int32 forward_limit:int32 = Ok;
+
+//@description Adds multiple new members to a chat. Currently this option is only available for supergroups and channels. This option can't be used to join a chat. Members can't be added to a channel if it has more than 200 members. Members will not be added until the chat state has been synchronized with the server
+//@chat_id Chat identifier @user_ids Identifiers of the users to be added to the chat
+addChatMembers chat_id:int53 user_ids:vector<int32> = Ok;
+
+//@description Changes the status of a chat member, needs appropriate privileges. This function is currently not suitable for adding new members to the chat; instead, use addChatMember. The chat member status will not be changed until it has been synchronized with the server
+//@chat_id Chat identifier @user_id User identifier @status The new status of the member in the chat
+setChatMemberStatus chat_id:int53 user_id:int32 status:ChatMemberStatus = Ok;
+
+//@description Returns information about a single member of a chat @chat_id Chat identifier @user_id User identifier
+getChatMember chat_id:int53 user_id:int32 = ChatMember;
+
+//@description Searches for a specified query in the first name, last name and username of the members of a specified chat. Requires administrator rights in channels @chat_id Chat identifier @query Query to search for @limit The maximum number of users to be returned
+searchChatMembers chat_id:int53 query:string limit:int32 = ChatMembers;
+
+//@description Returns a list of users who are administrators of the chat @chat_id Chat identifier
+getChatAdministrators chat_id:int53 = Users;
+
+
+//@description Changes the order of pinned chats @chat_ids The new list of pinned chats
+setPinnedChats chat_ids:vector<int53> = Ok;
+
+
+//@description Asynchronously downloads a file from the cloud. updateFile will be used to notify about the download progress and successful completion of the download. Returns file state just after the download has been started
+//@file_id Identifier of the file to download
+//@priority Priority of the download (1-32). The higher the priority, the earlier the file will be downloaded. If the priorities of two files are equal, then the last one for which downloadFile was called will be downloaded first
+downloadFile file_id:int32 priority:int32 = File;
+
+//@description Stops the downloading of a file. If a file has already been downloaded, does nothing @file_id Identifier of a file to stop downloading @only_if_pending Pass true to stop downloading only if it hasn't been started, i.e. request hasn't been sent to server
+cancelDownloadFile file_id:int32 only_if_pending:Bool = Ok;
+
+//@description Asynchronously uploads a file to the cloud without sending it in a message. updateFile will be used to notify about upload progress and successful completion of the upload. The file will not have a persistent remote identifier until it will be sent in a message @file File to upload @file_type File type
+//@priority Priority of the upload (1-32). The higher the priority, the earlier the file will be uploaded. If the priorities of two files are equal, then the first one for which uploadFile was called will be uploaded first
+uploadFile file:InputFile file_type:FileType priority:int32 = File;
+
+//@description Stops the uploading of a file. Supported only for files uploaded by using uploadFile. For other files the behavior is undefined @file_id Identifier of the file to stop uploading
+cancelUploadFile file_id:int32 = Ok;
+
+//@description The next part of a file was generated
+//@generation_id The identifier of the generation process
+//@expected_size Expected size of the generated file, in bytes; 0 if unknown
+//@local_prefix_size The number of bytes already generated
+setFileGenerationProgress generation_id:int64 expected_size:int32 local_prefix_size:int32 = Ok;
+
+//@description Finishes the file generation
+//@generation_id The identifier of the generation process
+//@error If set, means that file generation has failed and should be terminated
+finishFileGeneration generation_id:int64 error:error = Ok;
+
+//@description Deletes a file from the TDLib file cache @file_id Identifier of the file to delete
+deleteFile file_id:int32 = Ok;
+
+
+//@description Generates a new invite link for a chat; the previously generated link is revoked. Available for basic groups, supergroups, and channels. In basic groups this can be called only by the group's creator; in supergroups and channels this requires appropriate administrator rights @chat_id Chat identifier
+generateChatInviteLink chat_id:int53 = ChatInviteLink;
+
+//@description Checks the validity of an invite link for a chat and returns information about the corresponding chat @invite_link Invite link to be checked; should begin with "https://t.me/joinchat/", "https://telegram.me/joinchat/", or "https://telegram.dog/joinchat/"
+checkChatInviteLink invite_link:string = ChatInviteLinkInfo;
+
+//@description Uses an invite link to add the current user to the chat if possible. The new member will not be added until the chat state has been synchronized with the server
+//@invite_link Invite link to import; should begin with "https://t.me/joinchat/", "https://telegram.me/joinchat/", or "https://telegram.dog/joinchat/"
+joinChatByInviteLink invite_link:string = Chat;
+
+
+//@description Creates a new call @user_id Identifier of the user to be called @protocol Description of the call protocols supported by the client
+createCall user_id:int32 protocol:callProtocol = CallId;
+
+//@description Accepts an incoming call @call_id Call identifier @protocol Description of the call protocols supported by the client
+acceptCall call_id:int32 protocol:callProtocol = Ok;
+
+//@description Discards a call @call_id Call identifier @is_disconnected True, if the user was disconnected @duration The call duration, in seconds @connection_id Identifier of the connection used during the call
+discardCall call_id:int32 is_disconnected:Bool duration:int32 connection_id:int64 = Ok;
+
+//@description Sends a call rating @call_id Call identifier @rating Call rating; 1-5 @comment An optional user comment if the rating is less than 5
+sendCallRating call_id:int32 rating:int32 comment:string = Ok;
+
+//@description Sends debug information for a call @call_id Call identifier @debug_information Debug information in application-specific format
+sendCallDebugInformation call_id:int32 debug_information:string = Ok;
+
+
+
+//@description Adds a user to the blacklist @user_id User identifier
+blockUser user_id:int32 = Ok;
+
+//@description Removes a user from the blacklist @user_id User identifier
+unblockUser user_id:int32 = Ok;
+
+//@description Returns users that were blocked by the current user @offset Number of users to skip in the result; must be non-negative @limit Maximum number of users to return; up to 100
+getBlockedUsers offset:int32 limit:int32 = Users;
+
+
+//@description Adds new contacts or edits existing contacts; contacts' user identifiers are ignored @contacts The list of contacts to import or edit
+importContacts contacts:vector<contact> = ImportedContacts;
+
+//@description Searches for the specified query in the first names, last names and usernames of the known user contacts @query Query to search for; can be empty to return all contacts @limit Maximum number of users to be returned
+searchContacts query:string limit:int32 = Users;
+
+//@description Removes users from the contacts list @user_ids Identifiers of users to be deleted
+removeContacts user_ids:vector<int32> = Ok;
+
+//@description Returns the total number of imported contacts
+getImportedContactCount = Count;
+
+//@description Changes imported contacts using the list of current user contacts saved on the device. Imports newly added contacts and, if at least the file database is enabled, deletes recently deleted contacts.
+//-Query result depends on the result of the previous query, so only one query is possible at the same time @contacts The new list of contacts
+changeImportedContacts contacts:vector<contact> = ImportedContacts;
+
+//@description Clears all imported contacts
+clearImportedContacts = Ok;
+
+
+//@description Returns the profile photos of a user. The result of this query may be outdated: some photos might have been deleted already @user_id User identifier @offset The number of photos to skip; must be non-negative @limit Maximum number of photos to be returned; up to 100
+getUserProfilePhotos user_id:int32 offset:int32 limit:int32 = UserProfilePhotos;
+
+
+//@description Returns stickers from the installed sticker sets that correspond to a given emoji. If the emoji is not empty, favorite and recently used stickers may also be returned @emoji String representation of emoji. If empty, returns all known installed stickers @limit Maximum number of stickers to be returned
+getStickers emoji:string limit:int32 = Stickers;
+
+//@description Searches for stickers from public sticker sets that correspond to a given emoji @emoji String representation of emoji; must be non-empty @limit Maximum number of stickers to be returned
+searchStickers emoji:string limit:int32 = Stickers;
+
+//@description Returns a list of installed sticker sets @is_masks Pass true to return mask sticker sets; pass false to return ordinary sticker sets
+getInstalledStickerSets is_masks:Bool = StickerSets;
+
+//@description Returns a list of archived sticker sets @is_masks Pass true to return mask stickers sets; pass false to return ordinary sticker sets @offset_sticker_set_id Identifier of the sticker set from which to return the result @limit Maximum number of sticker sets to return
+getArchivedStickerSets is_masks:Bool offset_sticker_set_id:int64 limit:int32 = StickerSets;
+
+//@description Returns a list of trending sticker sets
+getTrendingStickerSets = StickerSets;
+
+//@description Returns a list of sticker sets attached to a file. Currently only photos and videos can have attached sticker sets @file_id File identifier
+getAttachedStickerSets file_id:int32 = StickerSets;
+
+//@description Returns information about a sticker set by its identifier @set_id Identifier of the sticker set
+getStickerSet set_id:int64 = StickerSet;
+
+//@description Searches for a sticker set by its name @name Name of the sticker set
+searchStickerSet name:string = StickerSet;
+
+//@description Searches for installed sticker sets by looking for specified query in their title and name @is_masks Pass true to return mask sticker sets; pass false to return ordinary sticker sets @query Query to search for @limit Maximum number of sticker sets to return
+searchInstalledStickerSets is_masks:Bool query:string limit:int32 = StickerSets;
+
+//@description Searches for ordinary sticker sets by looking for specified query in their title and name. Excludes installed sticker sets from the results @query Query to search for
+searchStickerSets query:string = StickerSets;
+
+//@description Installs/uninstalls or activates/archives a sticker set @set_id Identifier of the sticker set @is_installed The new value of is_installed @is_archived The new value of is_archived. A sticker set can't be installed and archived simultaneously
+changeStickerSet set_id:int64 is_installed:Bool is_archived:Bool = Ok;
+
+//@description Informs the server that some trending sticker sets have been viewed by the user @sticker_set_ids Identifiers of viewed trending sticker sets
+viewTrendingStickerSets sticker_set_ids:vector<int64> = Ok;
+
+//@description Changes the order of installed sticker sets @is_masks Pass true to change the order of mask sticker sets; pass false to change the order of ordinary sticker sets @sticker_set_ids Identifiers of installed sticker sets in the new correct order
+reorderInstalledStickerSets is_masks:Bool sticker_set_ids:vector<int64> = Ok;
+
+//@description Returns a list of recently used stickers @is_attached Pass true to return stickers and masks that were recently attached to photos or video files; pass false to return recently sent stickers
+getRecentStickers is_attached:Bool = Stickers;
+
+//@description Manually adds a new sticker to the list of recently used stickers. The new sticker is added to the top of the list. If the sticker was already in the list, it is removed from the list first. Only stickers belonging to a sticker set can be added to this list
+//@is_attached Pass true to add the sticker to the list of stickers recently attached to photo or video files; pass false to add the sticker to the list of recently sent stickers @sticker Sticker file to add
+addRecentSticker is_attached:Bool sticker:InputFile = Stickers;
+
+//@description Removes a sticker from the list of recently used stickers @is_attached Pass true to remove the sticker from the list of stickers recently attached to photo or video files; pass false to remove the sticker from the list of recently sent stickers @sticker Sticker file to delete
+removeRecentSticker is_attached:Bool sticker:InputFile = Ok;
+
+//@description Clears the list of recently used stickers @is_attached Pass true to clear the list of stickers recently attached to photo or video files; pass false to clear the list of recently sent stickers
+clearRecentStickers is_attached:Bool = Ok;
+
+//@description Returns favorite stickers
+getFavoriteStickers = Stickers;
+
+//@description Adds a new sticker to the list of favorite stickers. The new sticker is added to the top of the list. If the sticker was already in the list, it is removed from the list first. Only stickers belonging to a sticker set can be added to this list
+//@sticker Sticker file to add
+addFavoriteSticker sticker:InputFile = Ok;
+
+//@description Removes a sticker from the list of favorite stickers @sticker Sticker file to delete from the list
+removeFavoriteSticker sticker:InputFile = Ok;
+
+//@description Returns emoji corresponding to a sticker @sticker Sticker file identifier
+getStickerEmojis sticker:InputFile = StickerEmojis;
+
+
+//@description Returns saved animations
+getSavedAnimations = Animations;
+
+//@description Manually adds a new animation to the list of saved animations. The new animation is added to the beginning of the list. If the animation was already in the list, it is removed first. Only non-secret video animations with MIME type "video/mp4" can be added to the list
+//@animation The animation file to be added. Only animations known to the server (i.e. successfully sent via a message) can be added to the list
+addSavedAnimation animation:InputFile = Ok;
+
+//@description Removes an animation from the list of saved animations @animation Animation file to be removed
+removeSavedAnimation animation:InputFile = Ok;
+
+
+//@description Returns up to 20 recently used inline bots in the order of their last usage
+getRecentInlineBots = Users;
+
+
+//@description Searches for recently used hashtags by their prefix @prefix Hashtag prefix to search for @limit Maximum number of hashtags to be returned
+searchHashtags prefix:string limit:int32 = Hashtags;
+
+//@description Removes a hashtag from the list of recently used hashtags @hashtag Hashtag to delete
+removeRecentHashtag hashtag:string = Ok;
+
+
+//@description Returns a web page preview by the text of the message. Do not call this function too often. Returns a 404 error if the web page has no preview @text Message text with formatting
+getWebPagePreview text:formattedText = WebPage;
+
+//@description Returns an instant view version of a web page if available. Returns a 404 error if the web page has no instant view page @url The web page URL @force_full If true, the full instant view for the web page will be returned
+getWebPageInstantView url:string force_full:Bool = WebPageInstantView;
+
+
+//@description Returns the notification settings for a given scope @scope Scope for which to return the notification settings information
+getNotificationSettings scope:NotificationSettingsScope = NotificationSettings;
+
+//@description Changes notification settings for a given scope @scope Scope for which to change the notification settings
+//@notification_settings The new notification settings for the given scope
+setNotificationSettings scope:NotificationSettingsScope notification_settings:notificationSettings = Ok;
+
+//@description Resets all notification settings to their default values. By default, the only muted chats are supergroups, the sound is set to "default" and message previews are shown
+resetAllNotificationSettings = Ok;
+
+
+//@description Uploads a new profile photo for the current user. If something changes, updateUser will be sent @photo Profile photo to set. inputFileId and inputFileRemote may still be unsupported
+setProfilePhoto photo:InputFile = Ok;
+
+//@description Deletes a profile photo. If something changes, updateUser will be sent @profile_photo_id Identifier of the profile photo to delete
+deleteProfilePhoto profile_photo_id:int64 = Ok;
+
+//@description Changes the first and last name of the current user. If something changes, updateUser will be sent @first_name The new value of the first name for the user; 1-255 characters @last_name The new value of the optional last name for the user; 0-255 characters
+setName first_name:string last_name:string = Ok;
+
+//@description Changes the bio of the current user @bio The new value of the user bio; 0-70 characters without line feeds
+setBio bio:string = Ok;
+
+//@description Changes the username of the current user. If something changes, updateUser will be sent @username The new value of the username. Use an empty string to remove the username
+setUsername username:string = Ok;
+
+//@description Changes the phone number of the user and sends an authentication code to the user's new phone number. On success, returns information about the sent code
+//@phone_number The new phone number of the user in international format @allow_flash_call Pass true if the code can be sent via flash call to the specified phone number @is_current_phone_number Pass true if the phone number is used on the current device. Ignored if allow_flash_call is false
+changePhoneNumber phone_number:string allow_flash_call:Bool is_current_phone_number:Bool = AuthenticationCodeInfo;
+
+//@description Re-sends the authentication code sent to confirm a new phone number for the user. Works only if the previously received authenticationCodeInfo next_code_type was not null
+resendChangePhoneNumberCode = AuthenticationCodeInfo;
+
+//@description Checks the authentication code sent to confirm a new phone number of the user @code Verification code received by SMS, phone call or flash call
+checkChangePhoneNumberCode code:string = Ok;
+
+
+//@description Returns all active sessions of the current user
+getActiveSessions = Sessions;
+
+//@description Terminates a session of the current user @session_id Session identifier
+terminateSession session_id:int64 = Ok;
+
+//@description Terminates all other sessions of the current user
+terminateAllOtherSessions = Ok;
+
+
+//@description Returns all website where the current user used Telegram to log in
+getConnectedWebsites = ConnectedWebsites;
+
+//@description Disconnects website from the current user's Telegram account @website_id Website identifier
+disconnectWebsite website_id:int64 = Ok;
+
+//@description Disconnects all websites from the current user's Telegram account
+disconnectAllWebsites = Ok;
+
+
+//@description Toggles the "All members are admins" setting in basic groups; requires creator privileges in the group @basic_group_id Identifier of the basic group @everyone_is_administrator New value of everyone_is_administrator
+toggleBasicGroupAdministrators basic_group_id:int32 everyone_is_administrator:Bool = Ok;
+
+
+//@description Changes the username of a supergroup or channel, requires creator privileges in the supergroup or channel @supergroup_id Identifier of the supergroup or channel @username New value of the username. Use an empty string to remove the username
+setSupergroupUsername supergroup_id:int32 username:string = Ok;
+
+//@description Changes the sticker set of a supergroup; requires appropriate rights in the supergroup @supergroup_id Identifier of the supergroup @sticker_set_id New value of the supergroup sticker set identifier. Use 0 to remove the supergroup sticker set
+setSupergroupStickerSet supergroup_id:int32 sticker_set_id:int64 = Ok;
+
+//@description Toggles whether all members of a supergroup can add new members; requires appropriate administrator rights in the supergroup. @supergroup_id Identifier of the supergroup @anyone_can_invite New value of anyone_can_invite
+toggleSupergroupInvites supergroup_id:int32 anyone_can_invite:Bool = Ok;
+
+//@description Toggles sender signatures messages sent in a channel; requires appropriate administrator rights in the channel. @supergroup_id Identifier of the channel @sign_messages New value of sign_messages
+toggleSupergroupSignMessages supergroup_id:int32 sign_messages:Bool = Ok;
+
+//@description Toggles whether the message history of a supergroup is available to new members; requires appropriate administrator rights in the supergroup. @supergroup_id The identifier of the supergroup @is_all_history_available The new value of is_all_history_available
+toggleSupergroupIsAllHistoryAvailable supergroup_id:int32 is_all_history_available:Bool = Ok;
+
+//@description Changes information about a supergroup or channel; requires appropriate administrator rights @supergroup_id Identifier of the supergroup or channel @param_description New supergroup or channel description; 0-255 characters
+setSupergroupDescription supergroup_id:int32 description:string = Ok;
+
+//@description Pins a message in a supergroup or channel; requires appropriate administrator rights in the supergroup or channel @supergroup_id Identifier of the supergroup or channel @message_id Identifier of the new pinned message @disable_notification True, if there should be no notification about the pinned message
+pinSupergroupMessage supergroup_id:int32 message_id:int53 disable_notification:Bool = Ok;
+
+//@description Removes the pinned message from a supergroup or channel; requires appropriate administrator rights in the supergroup or channel @supergroup_id Identifier of the supergroup or channel
+unpinSupergroupMessage supergroup_id:int32 = Ok;
+
+//@description Reports some messages from a user in a supergroup as spam @supergroup_id Supergroup identifier @user_id User identifier @message_ids Identifiers of messages sent in the supergroup by the user. This list must be non-empty
+reportSupergroupSpam supergroup_id:int32 user_id:int32 message_ids:vector<int53> = Ok;
+
+//@description Returns information about members or banned users in a supergroup or channel. Can be used only if SupergroupFullInfo.can_get_members == true; additionally, administrator privileges may be required for some filters @supergroup_id Identifier of the supergroup or channel
+//@filter The type of users to return. By default, supergroupMembersRecent @offset Number of users to skip @limit The maximum number of users be returned; up to 200
+getSupergroupMembers supergroup_id:int32 filter:SupergroupMembersFilter offset:int32 limit:int32 = ChatMembers;
+
+//@description Deletes a supergroup or channel along with all messages in the corresponding chat. This will release the supergroup or channel username and remove all members; requires creator privileges in the supergroup or channel. Chats with more than 1000 members can't be deleted using this method @supergroup_id Identifier of the supergroup or channel
+deleteSupergroup supergroup_id:int32 = Ok;
+
+
+//@description Closes a secret chat, effectively transfering its state to secretChatStateClosed @secret_chat_id Secret chat identifier
+closeSecretChat secret_chat_id:int32 = Ok;
+
+
+//@description Returns a list of service actions taken by chat members and administrators in the last 48 hours. Available only in supergroups and channels. Requires administrator rights. Returns results in reverse chronological order (i. e., in order of decreasing event_id)
+//@chat_id Chat identifier @query Search query by which to filter events @from_event_id Identifier of an event from which to return results. Use 0 to get results from the latest events @limit Maximum number of events to return; up to 100
+//@filters The types of events to return. By default, all types will be returned @user_ids User identifiers by which to filter events. By default, events relating to all users will be returned
+getChatEventLog chat_id:int53 query:string from_event_id:int64 limit:int32 filters:chatEventLogFilters user_ids:vector<int32> = ChatEvents;
+
+
+//@description Returns an invoice payment form. This method should be called when the user presses inlineKeyboardButtonBuy @chat_id Chat identifier of the Invoice message @message_id Message identifier
+getPaymentForm chat_id:int53 message_id:int53 = PaymentForm;
+
+//@description Validates the order information provided by a user and returns the available shipping options for a flexible invoice @chat_id Chat identifier of the Invoice message @message_id Message identifier @order_info The order information, provided by the user @allow_save True, if the order information can be saved
+validateOrderInfo chat_id:int53 message_id:int53 order_info:orderInfo allow_save:Bool = ValidatedOrderInfo;
+
+//@description Sends a filled-out payment form to the bot for final verification @chat_id Chat identifier of the Invoice message @message_id Message identifier @order_info_id Identifier returned by ValidateOrderInfo, or an empty string @shipping_option_id Identifier of a chosen shipping option, if applicable
+//@credentials The credentials chosen by user for payment
+sendPaymentForm chat_id:int53 message_id:int53 order_info_id:string shipping_option_id:string credentials:InputCredentials = PaymentResult;
+
+//@description Returns information about a successful payment @chat_id Chat identifier of the PaymentSuccessful message @message_id Message identifier
+getPaymentReceipt chat_id:int53 message_id:int53 = PaymentReceipt;
+
+//@description Returns saved order info, if any
+getSavedOrderInfo = OrderInfo;
+
+//@description Deletes saved order info
+deleteSavedOrderInfo = Ok;
+
+//@description Deletes saved credentials for all payment provider bots
+deleteSavedCredentials = Ok;
+
+
+//@description Returns a user that can be contacted to get support
+getSupportUser = User;
+
+//@description Returns background wallpapers
+getWallpapers = Wallpapers;
+
+
+//@description Registers the currently used device for receiving push notifications @device_token Device token @other_user_ids List of at most 100 user identifiers of other users currently using the client
+registerDevice device_token:DeviceToken other_user_ids:vector<int32> = Ok;
+
+
+//@description Returns t.me URLs recently visited by a newly registered user @referrer Google Play referrer to identify the user
+getRecentlyVisitedTMeUrls referrer:string = TMeUrls;
+
+
+//@description Changes user privacy settings @setting The privacy setting @rules The new privacy rules
+setUserPrivacySettingRules setting:UserPrivacySetting rules:userPrivacySettingRules = Ok;
+
+//@description Returns the current privacy settings @setting The privacy setting
+getUserPrivacySettingRules setting:UserPrivacySetting = UserPrivacySettingRules;
+
+
+//@description Returns the value of an option by its name. (Check the list of available options on https://core.telegram.org/tdlib/options.) Can be called before authorization
+//@name The name of the option
+getOption name:string = OptionValue;
+
+//@description Sets the value of an option. (Check the list of available options on https://core.telegram.org/tdlib/options.) Only writable options can be set. Can be called before authorization
+//@name The name of the option @value The new value of the option
+setOption name:string value:OptionValue = Ok;
+
+
+//@description Changes the period of inactivity after which the account of the current user will automatically be deleted @ttl New account TTL
+setAccountTtl ttl:accountTtl = Ok;
+
+//@description Returns the period of inactivity after which the account of the current user will automatically be deleted
+getAccountTtl = AccountTtl;
+
+//@description Deletes the account of the current user, deleting all information associated with the user from the server. The phone number of the account can be used to create a new account @reason The reason why the account was deleted; optional
+deleteAccount reason:string = Ok;
+
+
+//@description Returns information on whether the current chat can be reported as spam @chat_id Chat identifier
+getChatReportSpamState chat_id:int53 = ChatReportSpamState;
+
+//@description Used to let the server know whether a chat is spam or not. Can be used only if ChatReportSpamState.can_report_spam is true. After this request, ChatReportSpamState.can_report_spam becomes false forever @chat_id Chat identifier @is_spam_chat If true, the chat will be reported as spam; otherwise it will be marked as not spam
+changeChatReportSpamState chat_id:int53 is_spam_chat:Bool = Ok;
+
+//@description Reports a chat to the Telegram moderators. Supported only for supergroups, channels, or private chats with bots, since other chats can't be checked by moderators @chat_id Chat identifier @reason The reason for reporting the chat @message_ids Identifiers of reported messages, if any
+reportChat chat_id:int53 reason:ChatReportReason message_ids:vector<int53> = Ok;
+
+
+//@description Returns storage usage statistics @chat_limit Maximum number of chats with the largest storage usage for which separate statistics should be returned. All other chats will be grouped in entries with chat_id == 0. If the chat info database is not used, the chat_limit is ignored and is always set to 0
+getStorageStatistics chat_limit:int32 = StorageStatistics;
+
+//@description Quickly returns approximate storage usage statistics
+getStorageStatisticsFast = StorageStatisticsFast;
+
+//@description Optimizes storage usage, i.e. deletes some files and returns new storage usage statistics. Secret thumbnails can't be deleted
+//@size Limit on the total size of files after deletion. Pass -1 to use the default limit
+//@ttl Limit on the time that has passed since the last time a file was accessed (or creation time for some filesystems). Pass -1 to use the default limit
+//@count Limit on the total count of files after deletion. Pass -1 to use the default limit
+//@immunity_delay The amount of time after the creation of a file during which it can't be deleted, in seconds. Pass -1 to use the default value
+//@file_types If not empty, only files with the given type(s) are considered. By default, all types except thumbnails, profile photos, stickers and wallpapers are deleted
+//@chat_ids If not empty, only files from the given chats are considered. Use 0 as chat identifier to delete files not belonging to any chat (e.g., profile photos)
+//@exclude_chat_ids If not empty, files from the given chats are excluded. Use 0 as chat identifier to exclude all files not belonging to any chat (e.g., profile photos)
+//@chat_limit Same as in getStorageStatistics. Affects only returned statistics
+optimizeStorage size:int53 ttl:int32 count:int32 immunity_delay:int32 file_types:vector<FileType> chat_ids:vector<int53> exclude_chat_ids:vector<int53> chat_limit:int32 = StorageStatistics;
+
+
+//@description Sets the current network type. Can be called before authorization. Calling this method forces all network connections to reopen, mitigating the delay in switching between different networks, so it should be called whenever the network is changed, even if the network type remains the same.
+//-Network type is used to check whether the library can use the network at all and also for collecting detailed network data usage statistics @type The new network type. By default, networkTypeOther
+setNetworkType type:NetworkType = Ok;
+
+//@description Returns network data usage statistics. Can be called before authorization @only_current If true, returns only data for the current library launch
+getNetworkStatistics only_current:Bool = NetworkStatistics;
+
+//@description Adds the specified data to data usage statistics. Can be called before authorization @entry The network statistics entry with the data to be added to statistics
+addNetworkStatistics entry:NetworkStatisticsEntry = Ok;
+
+//@description Resets all network data usage statistics to zero. Can be called before authorization
+resetNetworkStatistics = Ok;
+
+
+//@description Informs the server about the number of pending bot updates if they haven't been processed for a long time; for bots only @pending_update_count The number of pending updates @error_message The last error message
+setBotUpdatesStatus pending_update_count:int32 error_message:string = Ok;
+
+
+//@description Uploads a PNG image with a sticker; for bots only; returns the uploaded file @user_id Sticker file owner @png_sticker PNG image with the sticker; must be up to 512 kB in size and fit in 512x512 square
+uploadStickerFile user_id:int32 png_sticker:InputFile = File;
+
+//@description Creates a new sticker set; for bots only. Returns the newly created sticker set @user_id Sticker set owner @title Sticker set title; 1-64 characters @name Sticker set name. Can contain only English letters, digits and underscores. Must end with *"_by_<bot username>"* (*<bot_username>* is case insensitive); 1-64 characters
+//@is_masks True, if stickers are masks @stickers List of stickers to be added to the set
+createNewStickerSet user_id:int32 title:string name:string is_masks:Bool stickers:vector<inputSticker> = StickerSet;
+
+//@description Adds a new sticker to a set; for bots only. Returns the sticker set @user_id Sticker set owner @name Sticker set name @sticker Sticker to add to the set
+addStickerToSet user_id:int32 name:string sticker:inputSticker = StickerSet;
+
+//@description Changes the position of a sticker in the set to which it belongs; for bots only. The sticker set must have been created by the bot @sticker Sticker @position New position of the sticker in the set, zero-based
+setStickerPositionInSet sticker:InputFile position:int32 = Ok;
+
+//@description Removes a sticker from the set to which it belongs; for bots only. The sticker set must have been created by the bot @sticker Sticker
+removeStickerFromSet sticker:InputFile = Ok;
+
+
+//@description Sends a custom request; for bots only @method The method name @parameters JSON-serialized method parameters
+sendCustomRequest method:string parameters:string = CustomRequestResult;
+
+//@description Answers a custom query; for bots only @custom_query_id Identifier of a custom query @data JSON-serialized answer to the query
+answerCustomQuery custom_query_id:int64 data:string = Ok;
+
+
+//@description Succeeds after a specified amount of time has passed. Can be called before authorization @seconds Number of seconds before the function returns
+setAlarm seconds:double = Ok;
+
+
+//@description Uses current user IP to found his country. Returns two-letter ISO 3166-1 alpha-2 country code. Can be called before authorization
+getCountryCode = Text;
+
+//@description Returns the default text for invitation messages to be used as a placeholder when the current user invites friends to Telegram
+getInviteText = Text;
+
+//@description Returns the terms of service. Can be called before authorization
+getTermsOfService = Text;
+
+
+//@description Sets the proxy server for network requests. Can be called before authorization @proxy Proxy server to use. Specify null to remove the proxy server
+setProxy proxy:Proxy = Ok;
+
+//@description Returns the proxy that is currently set up. Can be called before authorization
+getProxy = Proxy;
+
+
+//@description Does nothing; for testing only
+testCallEmpty = Ok;
+//@description Returns the received string; for testing only @x String to return
+testCallString x:string = TestString;
+//@description Returns the received bytes; for testing only @x Bytes to return
+testCallBytes x:bytes = TestBytes;
+//@description Returns the received vector of numbers; for testing only @x Vector of numbers to return
+testCallVectorInt x:vector<int32> = TestVectorInt;
+//@description Returns the received vector of objects containing a number; for testing only @x Vector of objects to return
+testCallVectorIntObject x:vector<testInt> = TestVectorIntObject;
+//@description For testing only request. Returns the received vector of strings; for testing only @x Vector of strings to return
+testCallVectorString x:vector<string> = TestVectorString;
+//@description Returns the received vector of objects containing a string; for testing only @x Vector of objects to return
+testCallVectorStringObject x:vector<testString> = TestVectorStringObject;
+//@description Returns the squared received number; for testing only @x Number to square
+testSquareInt x:int32 = TestInt;
+//@description Sends a simple network request to the Telegram servers; for testing only
+testNetwork = Ok;
+//@description Forces an updates.getDifference call to the Telegram servers; for testing only
+testGetDifference = Ok;
+//@description Does nothing and ensures that the Update object is used; for testing only
+testUseUpdate = Update;
+//@description Does nothing and ensures that the Error object is used; for testing only
+testUseError = Error;
diff --git a/libs/tdlib/td/td/generate/scheme/td_api.tlo b/libs/tdlib/td/td/generate/scheme/td_api.tlo
new file mode 100644
index 0000000000..4b7b647b2f
--- /dev/null
+++ b/libs/tdlib/td/td/generate/scheme/td_api.tlo
diff --git a/libs/tdlib/td/td/generate/scheme/telegram_api.tl b/libs/tdlib/td/td/generate/scheme/telegram_api.tl
new file mode 100644
index 0000000000..11e5f7f727
--- /dev/null
+++ b/libs/tdlib/td/td/generate/scheme/telegram_api.tl
@@ -0,0 +1,1105 @@
+int ? = Int;
+long ? = Long;
+double ? = Double;
+string ? = String;
+
+bytes = Bytes;
+
+true#3fedd339 = True;
+
+boolFalse#bc799737 = Bool;
+boolTrue#997275b5 = Bool;
+
+vector#1cb5c415 {t:Type} # [ t ] = Vector t;
+
+error#c4b9f9bb code:int text:string = Error;
+
+ipPort ipv4:int port:int = IpPort;
+help.configSimple#d997c3c5 date:int expires:int dc_id:int ip_port_list:Vector<ipPort> = help.ConfigSimple;
+
+---functions---
+
+test.useError = Error;
+test.useConfigSimple = help.ConfigSimple;
+
+---types---
+
+inputPeerEmpty#7f3b18ea = InputPeer;
+inputPeerSelf#7da07ec9 = InputPeer;
+inputPeerChat#179be863 chat_id:int = InputPeer;
+inputPeerUser#7b8e7de6 user_id:int access_hash:long = InputPeer;
+inputPeerChannel#20adaef8 channel_id:int access_hash:long = InputPeer;
+
+inputUserEmpty#b98886cf = InputUser;
+inputUserSelf#f7c1b13f = InputUser;
+inputUser#d8292816 user_id:int access_hash:long = InputUser;
+
+inputPhoneContact#f392b7f4 client_id:long phone:string first_name:string last_name:string = InputContact;
+
+inputFile#f52ff27f id:long parts:int name:string md5_checksum:string = InputFile;
+inputFileBig#fa4f0bb5 id:long parts:int name:string = InputFile;
+
+inputMediaEmpty#9664f57f = InputMedia;
+inputMediaUploadedPhoto#1e287d04 flags:# file:InputFile stickers:flags.0?Vector<InputDocument> ttl_seconds:flags.1?int = InputMedia;
+inputMediaPhoto#b3ba0635 flags:# id:InputPhoto ttl_seconds:flags.0?int = InputMedia;
+inputMediaGeoPoint#f9c44144 geo_point:InputGeoPoint = InputMedia;
+inputMediaContact#a6e45987 phone_number:string first_name:string last_name:string = InputMedia;
+inputMediaUploadedDocument#5b38c6c1 flags:# nosound_video:flags.3?true file:InputFile thumb:flags.2?InputFile mime_type:string attributes:Vector<DocumentAttribute> stickers:flags.0?Vector<InputDocument> ttl_seconds:flags.1?int = InputMedia;
+inputMediaDocument#23ab23d2 flags:# id:InputDocument ttl_seconds:flags.0?int = InputMedia;
+inputMediaVenue#c13d1c11 geo_point:InputGeoPoint title:string address:string provider:string venue_id:string venue_type:string = InputMedia;
+inputMediaGifExternal#4843b0fd url:string q:string = InputMedia;
+inputMediaPhotoExternal#e5bbfe1a flags:# url:string ttl_seconds:flags.0?int = InputMedia;
+inputMediaDocumentExternal#fb52dc99 flags:# url:string ttl_seconds:flags.0?int = InputMedia;
+inputMediaGame#d33f43f3 id:InputGame = InputMedia;
+inputMediaInvoice#f4e096c3 flags:# title:string description:string photo:flags.0?InputWebDocument invoice:Invoice payload:bytes provider:string provider_data:DataJSON start_param:string = InputMedia;
+inputMediaGeoLive#7b1a118f geo_point:InputGeoPoint period:int = InputMedia;
+
+inputChatPhotoEmpty#1ca48f57 = InputChatPhoto;
+inputChatUploadedPhoto#927c55b4 file:InputFile = InputChatPhoto;
+inputChatPhoto#8953ad37 id:InputPhoto = InputChatPhoto;
+
+inputGeoPointEmpty#e4c123d6 = InputGeoPoint;
+inputGeoPoint#f3b7acc9 lat:double long:double = InputGeoPoint;
+
+inputPhotoEmpty#1cd7bf0d = InputPhoto;
+inputPhoto#fb95c6c4 id:long access_hash:long = InputPhoto;
+
+inputFileLocation#14637196 volume_id:long local_id:int secret:long = InputFileLocation;
+inputEncryptedFileLocation#f5235d55 id:long access_hash:long = InputFileLocation;
+inputDocumentFileLocation#430f0724 id:long access_hash:long version:int = InputFileLocation;
+
+inputAppEvent#770656a8 time:double type:string peer:long data:string = InputAppEvent;
+
+peerUser#9db1bc6d user_id:int = Peer;
+peerChat#bad0e5bb chat_id:int = Peer;
+peerChannel#bddde532 channel_id:int = Peer;
+
+storage.fileUnknown#aa963b05 = storage.FileType;
+storage.filePartial#40bc6f52 = storage.FileType;
+storage.fileJpeg#7efe0e = storage.FileType;
+storage.fileGif#cae1aadf = storage.FileType;
+storage.filePng#a4f63c0 = storage.FileType;
+storage.filePdf#ae1e508d = storage.FileType;
+storage.fileMp3#528a0677 = storage.FileType;
+storage.fileMov#4b09ebbc = storage.FileType;
+storage.fileMp4#b3cea0e4 = storage.FileType;
+storage.fileWebp#1081464c = storage.FileType;
+
+fileLocationUnavailable#7c596b46 volume_id:long local_id:int secret:long = FileLocation;
+fileLocation#53d69076 dc_id:int volume_id:long local_id:int secret:long = FileLocation;
+
+userEmpty#200250ba id:int = User;
+user#2e13f4c3 flags:# self:flags.10?true contact:flags.11?true mutual_contact:flags.12?true deleted:flags.13?true bot:flags.14?true bot_chat_history:flags.15?true bot_nochats:flags.16?true verified:flags.17?true restricted:flags.18?true min:flags.20?true bot_inline_geo:flags.21?true id:int access_hash:flags.0?long first_name:flags.1?string last_name:flags.2?string username:flags.3?string phone:flags.4?string photo:flags.5?UserProfilePhoto status:flags.6?UserStatus bot_info_version:flags.14?int restriction_reason:flags.18?string bot_inline_placeholder:flags.19?string lang_code:flags.22?string = User;
+
+userProfilePhotoEmpty#4f11bae1 = UserProfilePhoto;
+userProfilePhoto#d559d8c8 photo_id:long photo_small:FileLocation photo_big:FileLocation = UserProfilePhoto;
+
+userStatusEmpty#9d05049 = UserStatus;
+userStatusOnline#edb93949 expires:int = UserStatus;
+userStatusOffline#8c703f was_online:int = UserStatus;
+userStatusRecently#e26f42f1 = UserStatus;
+userStatusLastWeek#7bf09fc = UserStatus;
+userStatusLastMonth#77ebc742 = UserStatus;
+
+chatEmpty#9ba2d800 id:int = Chat;
+chat#d91cdd54 flags:# creator:flags.0?true kicked:flags.1?true left:flags.2?true admins_enabled:flags.3?true admin:flags.4?true deactivated:flags.5?true id:int title:string photo:ChatPhoto participants_count:int date:int version:int migrated_to:flags.6?InputChannel = Chat;
+chatForbidden#7328bdb id:int title:string = Chat;
+channel#450b7115 flags:# creator:flags.0?true left:flags.2?true editor:flags.3?true broadcast:flags.5?true verified:flags.7?true megagroup:flags.8?true restricted:flags.9?true democracy:flags.10?true signatures:flags.11?true min:flags.12?true id:int access_hash:flags.13?long title:string username:flags.6?string photo:ChatPhoto date:int version:int restriction_reason:flags.9?string admin_rights:flags.14?ChannelAdminRights banned_rights:flags.15?ChannelBannedRights participants_count:flags.17?int = Chat;
+channelForbidden#289da732 flags:# broadcast:flags.5?true megagroup:flags.8?true id:int access_hash:long title:string until_date:flags.16?int = Chat;
+
+chatFull#2e02a614 id:int participants:ChatParticipants chat_photo:Photo notify_settings:PeerNotifySettings exported_invite:ExportedChatInvite bot_info:Vector<BotInfo> = ChatFull;
+channelFull#76af5481 flags:# can_view_participants:flags.3?true can_set_username:flags.6?true can_set_stickers:flags.7?true hidden_prehistory:flags.10?true id:int about:string participants_count:flags.0?int admins_count:flags.1?int kicked_count:flags.2?int banned_count:flags.2?int read_inbox_max_id:int read_outbox_max_id:int unread_count:int chat_photo:Photo notify_settings:PeerNotifySettings exported_invite:ExportedChatInvite bot_info:Vector<BotInfo> migrated_from_chat_id:flags.4?int migrated_from_max_id:flags.4?int pinned_msg_id:flags.5?int stickerset:flags.8?StickerSet available_min_id:flags.9?int = ChatFull;
+
+chatParticipant#c8d7493e user_id:int inviter_id:int date:int = ChatParticipant;
+chatParticipantCreator#da13538a user_id:int = ChatParticipant;
+chatParticipantAdmin#e2d6e436 user_id:int inviter_id:int date:int = ChatParticipant;
+
+chatParticipantsForbidden#fc900c2b flags:# chat_id:int self_participant:flags.0?ChatParticipant = ChatParticipants;
+chatParticipants#3f460fed chat_id:int participants:Vector<ChatParticipant> version:int = ChatParticipants;
+
+chatPhotoEmpty#37c1011c = ChatPhoto;
+chatPhoto#6153276a photo_small:FileLocation photo_big:FileLocation = ChatPhoto;
+
+messageEmpty#83e5de54 id:int = Message;
+message#44f9b43d flags:# out:flags.1?true mentioned:flags.4?true media_unread:flags.5?true silent:flags.13?true post:flags.14?true id:int from_id:flags.8?int to_id:Peer fwd_from:flags.2?MessageFwdHeader via_bot_id:flags.11?int reply_to_msg_id:flags.3?int date:int message:string media:flags.9?MessageMedia reply_markup:flags.6?ReplyMarkup entities:flags.7?Vector<MessageEntity> views:flags.10?int edit_date:flags.15?int post_author:flags.16?string grouped_id:flags.17?long = Message;
+messageService#9e19a1f6 flags:# out:flags.1?true mentioned:flags.4?true media_unread:flags.5?true silent:flags.13?true post:flags.14?true id:int from_id:flags.8?int to_id:Peer reply_to_msg_id:flags.3?int date:int action:MessageAction = Message;
+
+messageMediaEmpty#3ded6320 = MessageMedia;
+messageMediaPhoto#695150d7 flags:# photo:flags.0?Photo ttl_seconds:flags.2?int = MessageMedia;
+messageMediaGeo#56e0d474 geo:GeoPoint = MessageMedia;
+messageMediaContact#5e7d2f39 phone_number:string first_name:string last_name:string user_id:int = MessageMedia;
+messageMediaUnsupported#9f84f49e = MessageMedia;
+messageMediaDocument#9cb070d7 flags:# document:flags.0?Document ttl_seconds:flags.2?int = MessageMedia;
+messageMediaWebPage#a32dd600 webpage:WebPage = MessageMedia;
+messageMediaVenue#2ec0533f geo:GeoPoint title:string address:string provider:string venue_id:string venue_type:string = MessageMedia;
+messageMediaGame#fdb19008 game:Game = MessageMedia;
+messageMediaInvoice#84551347 flags:# shipping_address_requested:flags.1?true test:flags.3?true title:string description:string photo:flags.0?WebDocument receipt_msg_id:flags.2?int currency:string total_amount:long start_param:string = MessageMedia;
+messageMediaGeoLive#7c3c2609 geo:GeoPoint period:int = MessageMedia;
+
+messageActionEmpty#b6aef7b0 = MessageAction;
+messageActionChatCreate#a6638b9a title:string users:Vector<int> = MessageAction;
+messageActionChatEditTitle#b5a1ce5a title:string = MessageAction;
+messageActionChatEditPhoto#7fcb13a8 photo:Photo = MessageAction;
+messageActionChatDeletePhoto#95e3fbef = MessageAction;
+messageActionChatAddUser#488a7337 users:Vector<int> = MessageAction;
+messageActionChatDeleteUser#b2ae9b0c user_id:int = MessageAction;
+messageActionChatJoinedByLink#f89cf5e8 inviter_id:int = MessageAction;
+messageActionChannelCreate#95d2ac92 title:string = MessageAction;
+messageActionChatMigrateTo#51bdb021 channel_id:int = MessageAction;
+messageActionChannelMigrateFrom#b055eaee title:string chat_id:int = MessageAction;
+messageActionPinMessage#94bd38ed = MessageAction;
+messageActionHistoryClear#9fbab604 = MessageAction;
+messageActionGameScore#92a72876 game_id:long score:int = MessageAction;
+messageActionPaymentSentMe#8f31b327 flags:# currency:string total_amount:long payload:bytes info:flags.0?PaymentRequestedInfo shipping_option_id:flags.1?string charge:PaymentCharge = MessageAction;
+messageActionPaymentSent#40699cd0 currency:string total_amount:long = MessageAction;
+messageActionPhoneCall#80e11a7f flags:# call_id:long reason:flags.0?PhoneCallDiscardReason duration:flags.1?int = MessageAction;
+messageActionScreenshotTaken#4792929b = MessageAction;
+messageActionCustomAction#fae69f56 message:string = MessageAction;
+messageActionBotAllowed#abe9affe domain:string = MessageAction;
+
+dialog#e4def5db flags:# pinned:flags.2?true peer:Peer top_message:int read_inbox_max_id:int read_outbox_max_id:int unread_count:int unread_mentions_count:int notify_settings:PeerNotifySettings pts:flags.0?int draft:flags.1?DraftMessage = Dialog;
+
+photoEmpty#2331b22d id:long = Photo;
+photo#9288dd29 flags:# has_stickers:flags.0?true id:long access_hash:long date:int sizes:Vector<PhotoSize> = Photo;
+
+photoSizeEmpty#e17e23c type:string = PhotoSize;
+photoSize#77bfb61b type:string location:FileLocation w:int h:int size:int = PhotoSize;
+photoCachedSize#e9a734fa type:string location:FileLocation w:int h:int bytes:bytes = PhotoSize;
+
+geoPointEmpty#1117dd5f = GeoPoint;
+geoPoint#2049d70c long:double lat:double = GeoPoint;
+
+auth.checkedPhone#811ea28e phone_registered:Bool = auth.CheckedPhone;
+
+auth.sentCode#5e002502 flags:# phone_registered:flags.0?true type:auth.SentCodeType phone_code_hash:string next_type:flags.1?auth.CodeType timeout:flags.2?int = auth.SentCode;
+
+auth.authorization#cd050916 flags:# tmp_sessions:flags.0?int user:User = auth.Authorization;
+
+auth.exportedAuthorization#df969c2d id:int bytes:bytes = auth.ExportedAuthorization;
+
+inputNotifyPeer#b8bc5b0c peer:InputPeer = InputNotifyPeer;
+inputNotifyUsers#193b4417 = InputNotifyPeer;
+inputNotifyChats#4a95e84e = InputNotifyPeer;
+inputNotifyAll#a429b886 = InputNotifyPeer;
+
+inputPeerNotifyEventsEmpty#f03064d8 = InputPeerNotifyEvents;
+inputPeerNotifyEventsAll#e86a2c74 = InputPeerNotifyEvents;
+
+inputPeerNotifySettings#38935eb2 flags:# show_previews:flags.0?true silent:flags.1?true mute_until:int sound:string = InputPeerNotifySettings;
+
+peerNotifyEventsEmpty#add53cb3 = PeerNotifyEvents;
+peerNotifyEventsAll#6d1ded88 = PeerNotifyEvents;
+
+peerNotifySettingsEmpty#70a68512 = PeerNotifySettings;
+peerNotifySettings#9acda4c0 flags:# show_previews:flags.0?true silent:flags.1?true mute_until:int sound:string = PeerNotifySettings;
+
+peerSettings#818426cd flags:# report_spam:flags.0?true = PeerSettings;
+
+wallPaper#ccb03657 id:int title:string sizes:Vector<PhotoSize> color:int = WallPaper;
+wallPaperSolid#63117f24 id:int title:string bg_color:int color:int = WallPaper;
+
+inputReportReasonSpam#58dbcab8 = ReportReason;
+inputReportReasonViolence#1e22c78d = ReportReason;
+inputReportReasonPornography#2e59d922 = ReportReason;
+inputReportReasonOther#e1746d0a text:string = ReportReason;
+
+userFull#f220f3f flags:# blocked:flags.0?true phone_calls_available:flags.4?true phone_calls_private:flags.5?true user:User about:flags.1?string link:contacts.Link profile_photo:flags.2?Photo notify_settings:PeerNotifySettings bot_info:flags.3?BotInfo common_chats_count:int = UserFull;
+
+contact#f911c994 user_id:int mutual:Bool = Contact;
+
+importedContact#d0028438 user_id:int client_id:long = ImportedContact;
+
+contactBlocked#561bc879 user_id:int date:int = ContactBlocked;
+
+contactStatus#d3680c61 user_id:int status:UserStatus = ContactStatus;
+
+contacts.link#3ace484c my_link:ContactLink foreign_link:ContactLink user:User = contacts.Link;
+
+contacts.contactsNotModified#b74ba9d2 = contacts.Contacts;
+contacts.contacts#eae87e42 contacts:Vector<Contact> saved_count:int users:Vector<User> = contacts.Contacts;
+
+contacts.importedContacts#77d01c3b imported:Vector<ImportedContact> popular_invites:Vector<PopularContact> retry_contacts:Vector<long> users:Vector<User> = contacts.ImportedContacts;
+
+contacts.blocked#1c138d15 blocked:Vector<ContactBlocked> users:Vector<User> = contacts.Blocked;
+contacts.blockedSlice#900802a1 count:int blocked:Vector<ContactBlocked> users:Vector<User> = contacts.Blocked;
+
+messages.dialogs#15ba6c40 dialogs:Vector<Dialog> messages:Vector<Message> chats:Vector<Chat> users:Vector<User> = messages.Dialogs;
+messages.dialogsSlice#71e094f3 count:int dialogs:Vector<Dialog> messages:Vector<Message> chats:Vector<Chat> users:Vector<User> = messages.Dialogs;
+
+messages.messages#8c718e87 messages:Vector<Message> chats:Vector<Chat> users:Vector<User> = messages.Messages;
+messages.messagesSlice#b446ae3 count:int messages:Vector<Message> chats:Vector<Chat> users:Vector<User> = messages.Messages;
+messages.channelMessages#99262e37 flags:# pts:int count:int messages:Vector<Message> chats:Vector<Chat> users:Vector<User> = messages.Messages;
+messages.messagesNotModified#74535f21 count:int = messages.Messages;
+
+messages.chats#64ff9fd5 chats:Vector<Chat> = messages.Chats;
+messages.chatsSlice#9cd81144 count:int chats:Vector<Chat> = messages.Chats;
+
+messages.chatFull#e5d7d19c full_chat:ChatFull chats:Vector<Chat> users:Vector<User> = messages.ChatFull;
+
+messages.affectedHistory#b45c69d1 pts:int pts_count:int offset:int = messages.AffectedHistory;
+
+inputMessagesFilterEmpty#57e2f66c = MessagesFilter;
+inputMessagesFilterPhotos#9609a51c = MessagesFilter;
+inputMessagesFilterVideo#9fc00e65 = MessagesFilter;
+inputMessagesFilterPhotoVideo#56e9f0e4 = MessagesFilter;
+inputMessagesFilterDocument#9eddf188 = MessagesFilter;
+inputMessagesFilterUrl#7ef0dd87 = MessagesFilter;
+inputMessagesFilterGif#ffc86587 = MessagesFilter;
+inputMessagesFilterVoice#50f5c392 = MessagesFilter;
+inputMessagesFilterMusic#3751b49e = MessagesFilter;
+inputMessagesFilterChatPhotos#3a20ecb8 = MessagesFilter;
+inputMessagesFilterPhoneCalls#80c99768 flags:# missed:flags.0?true = MessagesFilter;
+inputMessagesFilterRoundVoice#7a7c17a4 = MessagesFilter;
+inputMessagesFilterRoundVideo#b549da53 = MessagesFilter;
+inputMessagesFilterMyMentions#c1f8e69a = MessagesFilter;
+inputMessagesFilterGeo#e7026d0d = MessagesFilter;
+inputMessagesFilterContacts#e062db83 = MessagesFilter;
+
+updateNewMessage#1f2b0afd message:Message pts:int pts_count:int = Update;
+updateMessageID#4e90bfd6 id:int random_id:long = Update;
+updateDeleteMessages#a20db0e5 messages:Vector<int> pts:int pts_count:int = Update;
+updateUserTyping#5c486927 user_id:int action:SendMessageAction = Update;
+updateChatUserTyping#9a65ea1f chat_id:int user_id:int action:SendMessageAction = Update;
+updateChatParticipants#7761198 participants:ChatParticipants = Update;
+updateUserStatus#1bfbd823 user_id:int status:UserStatus = Update;
+updateUserName#a7332b73 user_id:int first_name:string last_name:string username:string = Update;
+updateUserPhoto#95313b0c user_id:int date:int photo:UserProfilePhoto previous:Bool = Update;
+updateContactRegistered#2575bbb9 user_id:int date:int = Update;
+updateContactLink#9d2e67c5 user_id:int my_link:ContactLink foreign_link:ContactLink = Update;
+updateNewEncryptedMessage#12bcbd9a message:EncryptedMessage qts:int = Update;
+updateEncryptedChatTyping#1710f156 chat_id:int = Update;
+updateEncryption#b4a2e88d chat:EncryptedChat date:int = Update;
+updateEncryptedMessagesRead#38fe25b7 chat_id:int max_date:int date:int = Update;
+updateChatParticipantAdd#ea4b0e5c chat_id:int user_id:int inviter_id:int date:int version:int = Update;
+updateChatParticipantDelete#6e5f8c22 chat_id:int user_id:int version:int = Update;
+updateDcOptions#8e5e9873 dc_options:Vector<DcOption> = Update;
+updateUserBlocked#80ece81a user_id:int blocked:Bool = Update;
+updateNotifySettings#bec268ef peer:NotifyPeer notify_settings:PeerNotifySettings = Update;
+updateServiceNotification#ebe46819 flags:# popup:flags.0?true inbox_date:flags.1?int type:string message:string media:MessageMedia entities:Vector<MessageEntity> = Update;
+updatePrivacy#ee3b272a key:PrivacyKey rules:Vector<PrivacyRule> = Update;
+updateUserPhone#12b9417b user_id:int phone:string = Update;
+updateReadHistoryInbox#9961fd5c peer:Peer max_id:int pts:int pts_count:int = Update;
+updateReadHistoryOutbox#2f2f21bf peer:Peer max_id:int pts:int pts_count:int = Update;
+updateWebPage#7f891213 webpage:WebPage pts:int pts_count:int = Update;
+updateReadMessagesContents#68c13933 messages:Vector<int> pts:int pts_count:int = Update;
+updateChannelTooLong#eb0467fb flags:# channel_id:int pts:flags.0?int = Update;
+updateChannel#b6d45656 channel_id:int = Update;
+updateNewChannelMessage#62ba04d9 message:Message pts:int pts_count:int = Update;
+updateReadChannelInbox#4214f37f channel_id:int max_id:int = Update;
+updateDeleteChannelMessages#c37521c9 channel_id:int messages:Vector<int> pts:int pts_count:int = Update;
+updateChannelMessageViews#98a12b4b channel_id:int id:int views:int = Update;
+updateChatAdmins#6e947941 chat_id:int enabled:Bool version:int = Update;
+updateChatParticipantAdmin#b6901959 chat_id:int user_id:int is_admin:Bool version:int = Update;
+updateNewStickerSet#688a30aa stickerset:messages.StickerSet = Update;
+updateStickerSetsOrder#bb2d201 flags:# masks:flags.0?true order:Vector<long> = Update;
+updateStickerSets#43ae3dec = Update;
+updateSavedGifs#9375341e = Update;
+updateBotInlineQuery#54826690 flags:# query_id:long user_id:int query:string geo:flags.0?GeoPoint offset:string = Update;
+updateBotInlineSend#e48f964 flags:# user_id:int query:string geo:flags.0?GeoPoint id:string msg_id:flags.1?InputBotInlineMessageID = Update;
+updateEditChannelMessage#1b3f4df7 message:Message pts:int pts_count:int = Update;
+updateChannelPinnedMessage#98592475 channel_id:int id:int = Update;
+updateBotCallbackQuery#e73547e1 flags:# query_id:long user_id:int peer:Peer msg_id:int chat_instance:long data:flags.0?bytes game_short_name:flags.1?string = Update;
+updateEditMessage#e40370a3 message:Message pts:int pts_count:int = Update;
+updateInlineBotCallbackQuery#f9d27a5a flags:# query_id:long user_id:int msg_id:InputBotInlineMessageID chat_instance:long data:flags.0?bytes game_short_name:flags.1?string = Update;
+updateReadChannelOutbox#25d6c9c7 channel_id:int max_id:int = Update;
+updateDraftMessage#ee2bb969 peer:Peer draft:DraftMessage = Update;
+updateReadFeaturedStickers#571d2742 = Update;
+updateRecentStickers#9a422c20 = Update;
+updateConfig#a229dd06 = Update;
+updatePtsChanged#3354678f = Update;
+updateChannelWebPage#40771900 channel_id:int webpage:WebPage pts:int pts_count:int = Update;
+updateDialogPinned#19d27f3c flags:# pinned:flags.0?true peer:DialogPeer = Update;
+updatePinnedDialogs#ea4cb65b flags:# order:flags.0?Vector<DialogPeer> = Update;
+updateBotWebhookJSON#8317c0c3 data:DataJSON = Update;
+updateBotWebhookJSONQuery#9b9240a6 query_id:long data:DataJSON timeout:int = Update;
+updateBotShippingQuery#e0cdc940 query_id:long user_id:int payload:bytes shipping_address:PostAddress = Update;
+updateBotPrecheckoutQuery#5d2f3aa9 flags:# query_id:long user_id:int payload:bytes info:flags.0?PaymentRequestedInfo shipping_option_id:flags.1?string currency:string total_amount:long = Update;
+updatePhoneCall#ab0f6b1e phone_call:PhoneCall = Update;
+updateLangPackTooLong#10c2404b = Update;
+updateLangPack#56022f4d difference:LangPackDifference = Update;
+updateFavedStickers#e511996d = Update;
+updateChannelReadMessagesContents#89893b45 channel_id:int messages:Vector<int> = Update;
+updateContactsReset#7084a7be = Update;
+updateChannelAvailableMessages#70db6837 channel_id:int available_min_id:int = Update;
+
+updates.state#a56c2a3e pts:int qts:int date:int seq:int unread_count:int = updates.State;
+
+updates.differenceEmpty#5d75a138 date:int seq:int = updates.Difference;
+updates.difference#f49ca0 new_messages:Vector<Message> new_encrypted_messages:Vector<EncryptedMessage> other_updates:Vector<Update> chats:Vector<Chat> users:Vector<User> state:updates.State = updates.Difference;
+updates.differenceSlice#a8fb1981 new_messages:Vector<Message> new_encrypted_messages:Vector<EncryptedMessage> other_updates:Vector<Update> chats:Vector<Chat> users:Vector<User> intermediate_state:updates.State = updates.Difference;
+updates.differenceTooLong#4afe8f6d pts:int = updates.Difference;
+
+updatesTooLong#e317af7e = Updates;
+updateShortMessage#914fbf11 flags:# out:flags.1?true mentioned:flags.4?true media_unread:flags.5?true silent:flags.13?true id:int user_id:int message:string pts:int pts_count:int date:int fwd_from:flags.2?MessageFwdHeader via_bot_id:flags.11?int reply_to_msg_id:flags.3?int entities:flags.7?Vector<MessageEntity> = Updates;
+updateShortChatMessage#16812688 flags:# out:flags.1?true mentioned:flags.4?true media_unread:flags.5?true silent:flags.13?true id:int from_id:int chat_id:int message:string pts:int pts_count:int date:int fwd_from:flags.2?MessageFwdHeader via_bot_id:flags.11?int reply_to_msg_id:flags.3?int entities:flags.7?Vector<MessageEntity> = Updates;
+updateShort#78d4dec1 update:Update date:int = Updates;
+updatesCombined#725b04c3 updates:Vector<Update> users:Vector<User> chats:Vector<Chat> date:int seq_start:int seq:int = Updates;
+updates#74ae4240 updates:Vector<Update> users:Vector<User> chats:Vector<Chat> date:int seq:int = Updates;
+updateShortSentMessage#11f1331c flags:# out:flags.1?true id:int pts:int pts_count:int date:int media:flags.9?MessageMedia entities:flags.7?Vector<MessageEntity> = Updates;
+
+photos.photos#8dca6aa5 photos:Vector<Photo> users:Vector<User> = photos.Photos;
+photos.photosSlice#15051f54 count:int photos:Vector<Photo> users:Vector<User> = photos.Photos;
+
+photos.photo#20212ca8 photo:Photo users:Vector<User> = photos.Photo;
+
+upload.file#96a18d5 type:storage.FileType mtime:int bytes:bytes = upload.File;
+upload.fileCdnRedirect#f18cda44 dc_id:int file_token:bytes encryption_key:bytes encryption_iv:bytes file_hashes:Vector<FileHash> = upload.File;
+
+dcOption#5d8c6cc flags:# ipv6:flags.0?true media_only:flags.1?true tcpo_only:flags.2?true cdn:flags.3?true static:flags.4?true id:int ip_address:string port:int = DcOption;
+
+config#86b5778e flags:# phonecalls_enabled:flags.1?true default_p2p_contacts:flags.3?true preload_featured_stickers:flags.4?true ignore_phone_entities:flags.5?true revoke_pm_inbox:flags.6?true date:int expires:int test_mode:Bool this_dc:int dc_options:Vector<DcOption> chat_size_max:int megagroup_size_max:int forwarded_count_max:int online_update_period_ms:int offline_blur_timeout_ms:int offline_idle_timeout_ms:int online_cloud_timeout_ms:int notify_cloud_delay_ms:int notify_default_delay_ms:int push_chat_period_ms:int push_chat_limit:int saved_gifs_limit:int edit_time_limit:int revoke_time_limit:int revoke_pm_time_limit:int rating_e_decay:int stickers_recent_limit:int stickers_faved_limit:int channels_read_media_period:int tmp_sessions:flags.0?int pinned_dialogs_count_max:int call_receive_timeout_ms:int call_ring_timeout_ms:int call_connect_timeout_ms:int call_packet_timeout_ms:int me_url_prefix:string suggested_lang_code:flags.2?string lang_pack_version:flags.2?int = Config;
+
+nearestDc#8e1a1775 country:string this_dc:int nearest_dc:int = NearestDc;
+
+help.appUpdate#8987f311 id:int critical:Bool url:string text:string = help.AppUpdate;
+help.noAppUpdate#c45a6536 = help.AppUpdate;
+
+help.inviteText#18cb9f78 message:string = help.InviteText;
+
+encryptedChatEmpty#ab7ec0a0 id:int = EncryptedChat;
+encryptedChatWaiting#3bf703dc id:int access_hash:long date:int admin_id:int participant_id:int = EncryptedChat;
+encryptedChatRequested#c878527e id:int access_hash:long date:int admin_id:int participant_id:int g_a:bytes = EncryptedChat;
+encryptedChat#fa56ce36 id:int access_hash:long date:int admin_id:int participant_id:int g_a_or_b:bytes key_fingerprint:long = EncryptedChat;
+encryptedChatDiscarded#13d6dd27 id:int = EncryptedChat;
+
+inputEncryptedChat#f141b5e1 chat_id:int access_hash:long = InputEncryptedChat;
+
+encryptedFileEmpty#c21f497e = EncryptedFile;
+encryptedFile#4a70994c id:long access_hash:long size:int dc_id:int key_fingerprint:int = EncryptedFile;
+
+inputEncryptedFileEmpty#1837c364 = InputEncryptedFile;
+inputEncryptedFileUploaded#64bd0306 id:long parts:int md5_checksum:string key_fingerprint:int = InputEncryptedFile;
+inputEncryptedFile#5a17b5e5 id:long access_hash:long = InputEncryptedFile;
+inputEncryptedFileBigUploaded#2dc173c8 id:long parts:int key_fingerprint:int = InputEncryptedFile;
+
+encryptedMessage#ed18c118 random_id:long chat_id:int date:int bytes:bytes file:EncryptedFile = EncryptedMessage;
+encryptedMessageService#23734b06 random_id:long chat_id:int date:int bytes:bytes = EncryptedMessage;
+
+messages.dhConfigNotModified#c0e24635 random:bytes = messages.DhConfig;
+messages.dhConfig#2c221edd g:int p:bytes version:int random:bytes = messages.DhConfig;
+
+messages.sentEncryptedMessage#560f8935 date:int = messages.SentEncryptedMessage;
+messages.sentEncryptedFile#9493ff32 date:int file:EncryptedFile = messages.SentEncryptedMessage;
+
+inputDocumentEmpty#72f0eaae = InputDocument;
+inputDocument#18798952 id:long access_hash:long = InputDocument;
+
+documentEmpty#36f8c871 id:long = Document;
+document#87232bc7 id:long access_hash:long date:int mime_type:string size:int thumb:PhotoSize dc_id:int version:int attributes:Vector<DocumentAttribute> = Document;
+
+help.support#17c6b5f6 phone_number:string user:User = help.Support;
+
+notifyPeer#9fd40bd8 peer:Peer = NotifyPeer;
+notifyUsers#b4c83b4c = NotifyPeer;
+notifyChats#c007cec3 = NotifyPeer;
+notifyAll#74d07c60 = NotifyPeer;
+
+sendMessageTypingAction#16bf744e = SendMessageAction;
+sendMessageCancelAction#fd5ec8f5 = SendMessageAction;
+sendMessageRecordVideoAction#a187d66f = SendMessageAction;
+sendMessageUploadVideoAction#e9763aec progress:int = SendMessageAction;
+sendMessageRecordAudioAction#d52f73f7 = SendMessageAction;
+sendMessageUploadAudioAction#f351d7ab progress:int = SendMessageAction;
+sendMessageUploadPhotoAction#d1d34a26 progress:int = SendMessageAction;
+sendMessageUploadDocumentAction#aa0cd9e4 progress:int = SendMessageAction;
+sendMessageGeoLocationAction#176f8ba1 = SendMessageAction;
+sendMessageChooseContactAction#628cbc6f = SendMessageAction;
+sendMessageGamePlayAction#dd6a8f48 = SendMessageAction;
+sendMessageRecordRoundAction#88f27fbc = SendMessageAction;
+sendMessageUploadRoundAction#243e1c66 progress:int = SendMessageAction;
+
+contacts.found#b3134d9d my_results:Vector<Peer> results:Vector<Peer> chats:Vector<Chat> users:Vector<User> = contacts.Found;
+
+inputPrivacyKeyStatusTimestamp#4f96cb18 = InputPrivacyKey;
+inputPrivacyKeyChatInvite#bdfb0426 = InputPrivacyKey;
+inputPrivacyKeyPhoneCall#fabadc5f = InputPrivacyKey;
+
+privacyKeyStatusTimestamp#bc2eab30 = PrivacyKey;
+privacyKeyChatInvite#500e6dfa = PrivacyKey;
+privacyKeyPhoneCall#3d662b7b = PrivacyKey;
+
+inputPrivacyValueAllowContacts#d09e07b = InputPrivacyRule;
+inputPrivacyValueAllowAll#184b35ce = InputPrivacyRule;
+inputPrivacyValueAllowUsers#131cc67f users:Vector<InputUser> = InputPrivacyRule;
+inputPrivacyValueDisallowContacts#ba52007 = InputPrivacyRule;
+inputPrivacyValueDisallowAll#d66b66c9 = InputPrivacyRule;
+inputPrivacyValueDisallowUsers#90110467 users:Vector<InputUser> = InputPrivacyRule;
+
+privacyValueAllowContacts#fffe1bac = PrivacyRule;
+privacyValueAllowAll#65427b82 = PrivacyRule;
+privacyValueAllowUsers#4d5bbe0c users:Vector<int> = PrivacyRule;
+privacyValueDisallowContacts#f888fa1a = PrivacyRule;
+privacyValueDisallowAll#8b73e763 = PrivacyRule;
+privacyValueDisallowUsers#c7f49b7 users:Vector<int> = PrivacyRule;
+
+account.privacyRules#554abb6f rules:Vector<PrivacyRule> users:Vector<User> = account.PrivacyRules;
+
+accountDaysTTL#b8d0afdf days:int = AccountDaysTTL;
+
+documentAttributeImageSize#6c37c15c w:int h:int = DocumentAttribute;
+documentAttributeAnimated#11b58939 = DocumentAttribute;
+documentAttributeSticker#6319d612 flags:# mask:flags.1?true alt:string stickerset:InputStickerSet mask_coords:flags.0?MaskCoords = DocumentAttribute;
+documentAttributeVideo#ef02ce6 flags:# round_message:flags.0?true supports_streaming:flags.1?true duration:int w:int h:int = DocumentAttribute;
+documentAttributeAudio#9852f9c6 flags:# voice:flags.10?true duration:int title:flags.0?string performer:flags.1?string waveform:flags.2?bytes = DocumentAttribute;
+documentAttributeFilename#15590068 file_name:string = DocumentAttribute;
+documentAttributeHasStickers#9801d2f7 = DocumentAttribute;
+
+messages.stickersNotModified#f1749a22 = messages.Stickers;
+messages.stickers#8a8ecd32 hash:string stickers:Vector<Document> = messages.Stickers;
+
+stickerPack#12b299d4 emoticon:string documents:Vector<long> = StickerPack;
+
+messages.allStickersNotModified#e86602c3 = messages.AllStickers;
+messages.allStickers#edfd405f hash:int sets:Vector<StickerSet> = messages.AllStickers;
+
+messages.affectedMessages#84d19185 pts:int pts_count:int = messages.AffectedMessages;
+
+contactLinkUnknown#5f4f9247 = ContactLink;
+contactLinkNone#feedd3ad = ContactLink;
+contactLinkHasPhone#268f3f59 = ContactLink;
+contactLinkContact#d502c2d0 = ContactLink;
+
+webPageEmpty#eb1477e8 id:long = WebPage;
+webPagePending#c586da1c id:long date:int = WebPage;
+webPage#5f07b4bc flags:# id:long url:string display_url:string hash:int type:flags.0?string site_name:flags.1?string title:flags.2?string description:flags.3?string photo:flags.4?Photo embed_url:flags.5?string embed_type:flags.5?string embed_width:flags.6?int embed_height:flags.6?int duration:flags.7?int author:flags.8?string document:flags.9?Document cached_page:flags.10?Page = WebPage;
+webPageNotModified#85849473 = WebPage;
+
+authorization#7bf2e6f6 hash:long flags:int device_model:string platform:string system_version:string api_id:int app_name:string app_version:string date_created:int date_active:int ip:string country:string region:string = Authorization;
+
+account.authorizations#1250abde authorizations:Vector<Authorization> = account.Authorizations;
+
+account.noPassword#96dabc18 new_salt:bytes email_unconfirmed_pattern:string = account.Password;
+account.password#7c18141c current_salt:bytes new_salt:bytes hint:string has_recovery:Bool email_unconfirmed_pattern:string = account.Password;
+
+account.passwordSettings#b7b72ab3 email:string = account.PasswordSettings;
+
+account.passwordInputSettings#86916deb flags:# new_salt:flags.0?bytes new_password_hash:flags.0?bytes hint:flags.0?string email:flags.1?string = account.PasswordInputSettings;
+
+auth.passwordRecovery#137948a5 email_pattern:string = auth.PasswordRecovery;
+
+receivedNotifyMessage#a384b779 id:int flags:int = ReceivedNotifyMessage;
+
+chatInviteEmpty#69df3769 = ExportedChatInvite;
+chatInviteExported#fc2e05bc link:string = ExportedChatInvite;
+
+chatInviteAlready#5a686d7c chat:Chat = ChatInvite;
+chatInvite#db74f558 flags:# channel:flags.0?true broadcast:flags.1?true public:flags.2?true megagroup:flags.3?true title:string photo:ChatPhoto participants_count:int participants:flags.4?Vector<User> = ChatInvite;
+
+inputStickerSetEmpty#ffb62b95 = InputStickerSet;
+inputStickerSetID#9de7a269 id:long access_hash:long = InputStickerSet;
+inputStickerSetShortName#861cc8a0 short_name:string = InputStickerSet;
+
+stickerSet#5585a139 flags:# archived:flags.1?true official:flags.2?true masks:flags.3?true installed_date:flags.0?int id:long access_hash:long title:string short_name:string count:int hash:int = StickerSet;
+
+messages.stickerSet#b60a24a6 set:StickerSet packs:Vector<StickerPack> documents:Vector<Document> = messages.StickerSet;
+
+botCommand#c27ac8c7 command:string description:string = BotCommand;
+
+botInfo#98e81d3a user_id:int description:string commands:Vector<BotCommand> = BotInfo;
+
+keyboardButton#a2fa4880 text:string = KeyboardButton;
+keyboardButtonUrl#258aff05 text:string url:string = KeyboardButton;
+keyboardButtonCallback#683a5e46 text:string data:bytes = KeyboardButton;
+keyboardButtonRequestPhone#b16a6c29 text:string = KeyboardButton;
+keyboardButtonRequestGeoLocation#fc796b3f text:string = KeyboardButton;
+keyboardButtonSwitchInline#568a748 flags:# same_peer:flags.0?true text:string query:string = KeyboardButton;
+keyboardButtonGame#50f41ccf text:string = KeyboardButton;
+keyboardButtonBuy#afd93fbb text:string = KeyboardButton;
+
+keyboardButtonRow#77608b83 buttons:Vector<KeyboardButton> = KeyboardButtonRow;
+
+replyKeyboardHide#a03e5b85 flags:# selective:flags.2?true = ReplyMarkup;
+replyKeyboardForceReply#f4108aa0 flags:# single_use:flags.1?true selective:flags.2?true = ReplyMarkup;
+replyKeyboardMarkup#3502758c flags:# resize:flags.0?true single_use:flags.1?true selective:flags.2?true rows:Vector<KeyboardButtonRow> = ReplyMarkup;
+replyInlineMarkup#48a30254 rows:Vector<KeyboardButtonRow> = ReplyMarkup;
+
+messageEntityUnknown#bb92ba95 offset:int length:int = MessageEntity;
+messageEntityMention#fa04579d offset:int length:int = MessageEntity;
+messageEntityHashtag#6f635b0d offset:int length:int = MessageEntity;
+messageEntityBotCommand#6cef8ac7 offset:int length:int = MessageEntity;
+messageEntityUrl#6ed02538 offset:int length:int = MessageEntity;
+messageEntityEmail#64e475c2 offset:int length:int = MessageEntity;
+messageEntityBold#bd610bc9 offset:int length:int = MessageEntity;
+messageEntityItalic#826f8b60 offset:int length:int = MessageEntity;
+messageEntityCode#28a20571 offset:int length:int = MessageEntity;
+messageEntityPre#73924be0 offset:int length:int language:string = MessageEntity;
+messageEntityTextUrl#76a6d327 offset:int length:int url:string = MessageEntity;
+messageEntityMentionName#352dca58 offset:int length:int user_id:int = MessageEntity;
+inputMessageEntityMentionName#208e68c9 offset:int length:int user_id:InputUser = MessageEntity;
+messageEntityPhone#9b69e34b offset:int length:int = MessageEntity;
+messageEntityCashtag#4c4e743f offset:int length:int = MessageEntity;
+
+inputChannelEmpty#ee8c1e86 = InputChannel;
+inputChannel#afeb712e channel_id:int access_hash:long = InputChannel;
+
+contacts.resolvedPeer#7f077ad9 peer:Peer chats:Vector<Chat> users:Vector<User> = contacts.ResolvedPeer;
+
+messageRange#ae30253 min_id:int max_id:int = MessageRange;
+
+updates.channelDifferenceEmpty#3e11affb flags:# final:flags.0?true pts:int timeout:flags.1?int = updates.ChannelDifference;
+updates.channelDifferenceTooLong#6a9d7b35 flags:# final:flags.0?true pts:int timeout:flags.1?int top_message:int read_inbox_max_id:int read_outbox_max_id:int unread_count:int unread_mentions_count:int messages:Vector<Message> chats:Vector<Chat> users:Vector<User> = updates.ChannelDifference;
+updates.channelDifference#2064674e flags:# final:flags.0?true pts:int timeout:flags.1?int new_messages:Vector<Message> other_updates:Vector<Update> chats:Vector<Chat> users:Vector<User> = updates.ChannelDifference;
+
+channelMessagesFilterEmpty#94d42ee7 = ChannelMessagesFilter;
+channelMessagesFilter#cd77d957 flags:# exclude_new_messages:flags.1?true ranges:Vector<MessageRange> = ChannelMessagesFilter;
+
+channelParticipant#15ebac1d user_id:int date:int = ChannelParticipant;
+channelParticipantSelf#a3289a6d user_id:int inviter_id:int date:int = ChannelParticipant;
+channelParticipantCreator#e3e2e1f9 user_id:int = ChannelParticipant;
+channelParticipantAdmin#a82fa898 flags:# can_edit:flags.0?true user_id:int inviter_id:int promoted_by:int date:int admin_rights:ChannelAdminRights = ChannelParticipant;
+channelParticipantBanned#222c1886 flags:# left:flags.0?true user_id:int kicked_by:int date:int banned_rights:ChannelBannedRights = ChannelParticipant;
+
+channelParticipantsRecent#de3f3c79 = ChannelParticipantsFilter;
+channelParticipantsAdmins#b4608969 = ChannelParticipantsFilter;
+channelParticipantsKicked#a3b54985 q:string = ChannelParticipantsFilter;
+channelParticipantsBots#b0d1865b = ChannelParticipantsFilter;
+channelParticipantsBanned#1427a5e1 q:string = ChannelParticipantsFilter;
+channelParticipantsSearch#656ac4b q:string = ChannelParticipantsFilter;
+
+channels.channelParticipants#f56ee2a8 count:int participants:Vector<ChannelParticipant> users:Vector<User> = channels.ChannelParticipants;
+channels.channelParticipantsNotModified#f0173fe9 = channels.ChannelParticipants;
+
+channels.channelParticipant#d0d9b163 participant:ChannelParticipant users:Vector<User> = channels.ChannelParticipant;
+
+help.termsOfService#f1ee3e90 text:string = help.TermsOfService;
+
+foundGif#162ecc1f url:string thumb_url:string content_url:string content_type:string w:int h:int = FoundGif;
+foundGifCached#9c750409 url:string photo:Photo document:Document = FoundGif;
+
+messages.foundGifs#450a1c0a next_offset:int results:Vector<FoundGif> = messages.FoundGifs;
+
+messages.savedGifsNotModified#e8025ca2 = messages.SavedGifs;
+messages.savedGifs#2e0709a5 hash:int gifs:Vector<Document> = messages.SavedGifs;
+
+inputBotInlineMessageMediaAuto#3380c786 flags:# message:string entities:flags.1?Vector<MessageEntity> reply_markup:flags.2?ReplyMarkup = InputBotInlineMessage;
+inputBotInlineMessageText#3dcd7a87 flags:# no_webpage:flags.0?true message:string entities:flags.1?Vector<MessageEntity> reply_markup:flags.2?ReplyMarkup = InputBotInlineMessage;
+inputBotInlineMessageMediaGeo#c1b15d65 flags:# geo_point:InputGeoPoint period:int reply_markup:flags.2?ReplyMarkup = InputBotInlineMessage;
+inputBotInlineMessageMediaVenue#aaafadc8 flags:# geo_point:InputGeoPoint title:string address:string provider:string venue_id:string reply_markup:flags.2?ReplyMarkup = InputBotInlineMessage;
+inputBotInlineMessageMediaContact#2daf01a7 flags:# phone_number:string first_name:string last_name:string reply_markup:flags.2?ReplyMarkup = InputBotInlineMessage;
+inputBotInlineMessageGame#4b425864 flags:# reply_markup:flags.2?ReplyMarkup = InputBotInlineMessage;
+
+inputBotInlineResult#88bf9319 flags:# id:string type:string title:flags.1?string description:flags.2?string url:flags.3?string thumb:flags.4?InputWebDocument content:flags.5?InputWebDocument send_message:InputBotInlineMessage = InputBotInlineResult;
+inputBotInlineResultPhoto#a8d864a7 id:string type:string photo:InputPhoto send_message:InputBotInlineMessage = InputBotInlineResult;
+inputBotInlineResultDocument#fff8fdc4 flags:# id:string type:string title:flags.1?string description:flags.2?string document:InputDocument send_message:InputBotInlineMessage = InputBotInlineResult;
+inputBotInlineResultGame#4fa417f2 id:string short_name:string send_message:InputBotInlineMessage = InputBotInlineResult;
+
+botInlineMessageMediaAuto#764cf810 flags:# message:string entities:flags.1?Vector<MessageEntity> reply_markup:flags.2?ReplyMarkup = BotInlineMessage;
+botInlineMessageText#8c7f65e2 flags:# no_webpage:flags.0?true message:string entities:flags.1?Vector<MessageEntity> reply_markup:flags.2?ReplyMarkup = BotInlineMessage;
+botInlineMessageMediaGeo#b722de65 flags:# geo:GeoPoint period:int reply_markup:flags.2?ReplyMarkup = BotInlineMessage;
+botInlineMessageMediaVenue#4366232e flags:# geo:GeoPoint title:string address:string provider:string venue_id:string reply_markup:flags.2?ReplyMarkup = BotInlineMessage;
+botInlineMessageMediaContact#35edb4d4 flags:# phone_number:string first_name:string last_name:string reply_markup:flags.2?ReplyMarkup = BotInlineMessage;
+
+botInlineResult#11965f3a flags:# id:string type:string title:flags.1?string description:flags.2?string url:flags.3?string thumb:flags.4?WebDocument content:flags.5?WebDocument send_message:BotInlineMessage = BotInlineResult;
+botInlineMediaResult#17db940b flags:# id:string type:string photo:flags.0?Photo document:flags.1?Document title:flags.2?string description:flags.3?string send_message:BotInlineMessage = BotInlineResult;
+
+messages.botResults#947ca848 flags:# gallery:flags.0?true query_id:long next_offset:flags.1?string switch_pm:flags.2?InlineBotSwitchPM results:Vector<BotInlineResult> cache_time:int users:Vector<User> = messages.BotResults;
+
+exportedMessageLink#5dab1af4 link:string html:string = ExportedMessageLink;
+
+messageFwdHeader#559ebe6d flags:# from_id:flags.0?int date:int channel_id:flags.1?int channel_post:flags.2?int post_author:flags.3?string saved_from_peer:flags.4?Peer saved_from_msg_id:flags.4?int = MessageFwdHeader;
+
+auth.codeTypeSms#72a3158c = auth.CodeType;
+auth.codeTypeCall#741cd3e3 = auth.CodeType;
+auth.codeTypeFlashCall#226ccefb = auth.CodeType;
+
+auth.sentCodeTypeApp#3dbb5986 length:int = auth.SentCodeType;
+auth.sentCodeTypeSms#c000bba2 length:int = auth.SentCodeType;
+auth.sentCodeTypeCall#5353e5a7 length:int = auth.SentCodeType;
+auth.sentCodeTypeFlashCall#ab03c6d9 pattern:string = auth.SentCodeType;
+
+messages.botCallbackAnswer#36585ea4 flags:# alert:flags.1?true has_url:flags.3?true native_ui:flags.4?true message:flags.0?string url:flags.2?string cache_time:int = messages.BotCallbackAnswer;
+
+messages.messageEditData#26b5dde6 flags:# caption:flags.0?true = messages.MessageEditData;
+
+inputBotInlineMessageID#890c3d89 dc_id:int id:long access_hash:long = InputBotInlineMessageID;
+
+inlineBotSwitchPM#3c20629f text:string start_param:string = InlineBotSwitchPM;
+
+messages.peerDialogs#3371c354 dialogs:Vector<Dialog> messages:Vector<Message> chats:Vector<Chat> users:Vector<User> state:updates.State = messages.PeerDialogs;
+
+topPeer#edcdc05b peer:Peer rating:double = TopPeer;
+
+topPeerCategoryBotsPM#ab661b5b = TopPeerCategory;
+topPeerCategoryBotsInline#148677e2 = TopPeerCategory;
+topPeerCategoryCorrespondents#637b7ed = TopPeerCategory;
+topPeerCategoryGroups#bd17a14a = TopPeerCategory;
+topPeerCategoryChannels#161d9628 = TopPeerCategory;
+topPeerCategoryPhoneCalls#1e76a78c = TopPeerCategory;
+
+topPeerCategoryPeers#fb834291 category:TopPeerCategory count:int peers:Vector<TopPeer> = TopPeerCategoryPeers;
+
+contacts.topPeersNotModified#de266ef5 = contacts.TopPeers;
+contacts.topPeers#70b772a8 categories:Vector<TopPeerCategoryPeers> chats:Vector<Chat> users:Vector<User> = contacts.TopPeers;
+
+draftMessageEmpty#ba4baec5 = DraftMessage;
+draftMessage#fd8e711f flags:# no_webpage:flags.1?true reply_to_msg_id:flags.0?int message:string entities:flags.3?Vector<MessageEntity> date:int = DraftMessage;
+
+messages.featuredStickersNotModified#4ede3cf = messages.FeaturedStickers;
+messages.featuredStickers#f89d88e5 hash:int sets:Vector<StickerSetCovered> unread:Vector<long> = messages.FeaturedStickers;
+
+messages.recentStickersNotModified#b17f890 = messages.RecentStickers;
+messages.recentStickers#22f3afb3 hash:int packs:Vector<StickerPack> stickers:Vector<Document> dates:Vector<int> = messages.RecentStickers;
+
+messages.archivedStickers#4fcba9c8 count:int sets:Vector<StickerSetCovered> = messages.ArchivedStickers;
+
+messages.stickerSetInstallResultSuccess#38641628 = messages.StickerSetInstallResult;
+messages.stickerSetInstallResultArchive#35e410a8 sets:Vector<StickerSetCovered> = messages.StickerSetInstallResult;
+
+stickerSetCovered#6410a5d2 set:StickerSet cover:Document = StickerSetCovered;
+stickerSetMultiCovered#3407e51b set:StickerSet covers:Vector<Document> = StickerSetCovered;
+
+maskCoords#aed6dbb2 n:int x:double y:double zoom:double = MaskCoords;
+
+inputStickeredMediaPhoto#4a992157 id:InputPhoto = InputStickeredMedia;
+inputStickeredMediaDocument#438865b id:InputDocument = InputStickeredMedia;
+
+game#bdf9653b flags:# id:long access_hash:long short_name:string title:string description:string photo:Photo document:flags.0?Document = Game;
+
+inputGameID#32c3e77 id:long access_hash:long = InputGame;
+inputGameShortName#c331e80a bot_id:InputUser short_name:string = InputGame;
+
+highScore#58fffcd0 pos:int user_id:int score:int = HighScore;
+
+messages.highScores#9a3bfd99 scores:Vector<HighScore> users:Vector<User> = messages.HighScores;
+
+textEmpty#dc3d824f = RichText;
+textPlain#744694e0 text:string = RichText;
+textBold#6724abc4 text:RichText = RichText;
+textItalic#d912a59c text:RichText = RichText;
+textUnderline#c12622c4 text:RichText = RichText;
+textStrike#9bf8bb95 text:RichText = RichText;
+textFixed#6c3f19b9 text:RichText = RichText;
+textUrl#3c2884c1 text:RichText url:string webpage_id:long = RichText;
+textEmail#de5a0dd6 text:RichText email:string = RichText;
+textConcat#7e6260d7 texts:Vector<RichText> = RichText;
+
+pageBlockUnsupported#13567e8a = PageBlock;
+pageBlockTitle#70abc3fd text:RichText = PageBlock;
+pageBlockSubtitle#8ffa9a1f text:RichText = PageBlock;
+pageBlockAuthorDate#baafe5e0 author:RichText published_date:int = PageBlock;
+pageBlockHeader#bfd064ec text:RichText = PageBlock;
+pageBlockSubheader#f12bb6e1 text:RichText = PageBlock;
+pageBlockParagraph#467a0766 text:RichText = PageBlock;
+pageBlockPreformatted#c070d93e text:RichText language:string = PageBlock;
+pageBlockFooter#48870999 text:RichText = PageBlock;
+pageBlockDivider#db20b188 = PageBlock;
+pageBlockAnchor#ce0d37b0 name:string = PageBlock;
+pageBlockList#3a58c7f4 ordered:Bool items:Vector<RichText> = PageBlock;
+pageBlockBlockquote#263d7c26 text:RichText caption:RichText = PageBlock;
+pageBlockPullquote#4f4456d3 text:RichText caption:RichText = PageBlock;
+pageBlockPhoto#e9c69982 photo_id:long caption:RichText = PageBlock;
+pageBlockVideo#d9d71866 flags:# autoplay:flags.0?true loop:flags.1?true video_id:long caption:RichText = PageBlock;
+pageBlockCover#39f23300 cover:PageBlock = PageBlock;
+pageBlockEmbed#cde200d1 flags:# full_width:flags.0?true allow_scrolling:flags.3?true url:flags.1?string html:flags.2?string poster_photo_id:flags.4?long w:int h:int caption:RichText = PageBlock;
+pageBlockEmbedPost#292c7be9 url:string webpage_id:long author_photo_id:long author:string date:int blocks:Vector<PageBlock> caption:RichText = PageBlock;
+pageBlockCollage#8b31c4f items:Vector<PageBlock> caption:RichText = PageBlock;
+pageBlockSlideshow#130c8963 items:Vector<PageBlock> caption:RichText = PageBlock;
+pageBlockChannel#ef1751b5 channel:Chat = PageBlock;
+pageBlockAudio#31b81a7f audio_id:long caption:RichText = PageBlock;
+
+pagePart#8e3f9ebe blocks:Vector<PageBlock> photos:Vector<Photo> documents:Vector<Document> = Page;
+pageFull#556ec7aa blocks:Vector<PageBlock> photos:Vector<Photo> documents:Vector<Document> = Page;
+
+phoneCallDiscardReasonMissed#85e42301 = PhoneCallDiscardReason;
+phoneCallDiscardReasonDisconnect#e095c1a0 = PhoneCallDiscardReason;
+phoneCallDiscardReasonHangup#57adc690 = PhoneCallDiscardReason;
+phoneCallDiscardReasonBusy#faf7e8c9 = PhoneCallDiscardReason;
+
+dataJSON#7d748d04 data:string = DataJSON;
+
+labeledPrice#cb296bf8 label:string amount:long = LabeledPrice;
+
+invoice#c30aa358 flags:# test:flags.0?true name_requested:flags.1?true phone_requested:flags.2?true email_requested:flags.3?true shipping_address_requested:flags.4?true flexible:flags.5?true phone_to_provider:flags.6?true email_to_provider:flags.7?true currency:string prices:Vector<LabeledPrice> = Invoice;
+
+paymentCharge#ea02c27e id:string provider_charge_id:string = PaymentCharge;
+
+postAddress#1e8caaeb street_line1:string street_line2:string city:string state:string country_iso2:string post_code:string = PostAddress;
+
+paymentRequestedInfo#909c3f94 flags:# name:flags.0?string phone:flags.1?string email:flags.2?string shipping_address:flags.3?PostAddress = PaymentRequestedInfo;
+
+paymentSavedCredentialsCard#cdc27a1f id:string title:string = PaymentSavedCredentials;
+
+webDocument#c61acbd8 url:string access_hash:long size:int mime_type:string attributes:Vector<DocumentAttribute> dc_id:int = WebDocument;
+webDocumentNoProxy#f9c8bcc6 url:string size:int mime_type:string attributes:Vector<DocumentAttribute> = WebDocument;
+
+inputWebDocument#9bed434d url:string size:int mime_type:string attributes:Vector<DocumentAttribute> = InputWebDocument;
+
+inputWebFileLocation#c239d686 url:string access_hash:long = InputWebFileLocation;
+
+upload.webFile#21e753bc size:int mime_type:string file_type:storage.FileType mtime:int bytes:bytes = upload.WebFile;
+
+payments.paymentForm#3f56aea3 flags:# can_save_credentials:flags.2?true password_missing:flags.3?true bot_id:int invoice:Invoice provider_id:int url:string native_provider:flags.4?string native_params:flags.4?DataJSON saved_info:flags.0?PaymentRequestedInfo saved_credentials:flags.1?PaymentSavedCredentials users:Vector<User> = payments.PaymentForm;
+
+payments.validatedRequestedInfo#d1451883 flags:# id:flags.0?string shipping_options:flags.1?Vector<ShippingOption> = payments.ValidatedRequestedInfo;
+
+payments.paymentResult#4e5f810d updates:Updates = payments.PaymentResult;
+payments.paymentVerficationNeeded#6b56b921 url:string = payments.PaymentResult;
+
+payments.paymentReceipt#500911e1 flags:# date:int bot_id:int invoice:Invoice provider_id:int info:flags.0?PaymentRequestedInfo shipping:flags.1?ShippingOption currency:string total_amount:long credentials_title:string users:Vector<User> = payments.PaymentReceipt;
+
+payments.savedInfo#fb8fe43c flags:# has_saved_credentials:flags.1?true saved_info:flags.0?PaymentRequestedInfo = payments.SavedInfo;
+
+inputPaymentCredentialsSaved#c10eb2cf id:string tmp_password:bytes = InputPaymentCredentials;
+inputPaymentCredentials#3417d728 flags:# save:flags.0?true data:DataJSON = InputPaymentCredentials;
+inputPaymentCredentialsApplePay#aa1c39f payment_data:DataJSON = InputPaymentCredentials;
+inputPaymentCredentialsAndroidPay#ca05d50e payment_token:DataJSON google_transaction_id:string = InputPaymentCredentials;
+
+account.tmpPassword#db64fd34 tmp_password:bytes valid_until:int = account.TmpPassword;
+
+shippingOption#b6213cdf id:string title:string prices:Vector<LabeledPrice> = ShippingOption;
+
+inputStickerSetItem#ffa0a496 flags:# document:InputDocument emoji:string mask_coords:flags.0?MaskCoords = InputStickerSetItem;
+
+inputPhoneCall#1e36fded id:long access_hash:long = InputPhoneCall;
+
+phoneCallEmpty#5366c915 id:long = PhoneCall;
+phoneCallWaiting#1b8f4ad1 flags:# id:long access_hash:long date:int admin_id:int participant_id:int protocol:PhoneCallProtocol receive_date:flags.0?int = PhoneCall;
+phoneCallRequested#83761ce4 id:long access_hash:long date:int admin_id:int participant_id:int g_a_hash:bytes protocol:PhoneCallProtocol = PhoneCall;
+phoneCallAccepted#6d003d3f id:long access_hash:long date:int admin_id:int participant_id:int g_b:bytes protocol:PhoneCallProtocol = PhoneCall;
+phoneCall#ffe6ab67 id:long access_hash:long date:int admin_id:int participant_id:int g_a_or_b:bytes key_fingerprint:long protocol:PhoneCallProtocol connection:PhoneConnection alternative_connections:Vector<PhoneConnection> start_date:int = PhoneCall;
+phoneCallDiscarded#50ca4de1 flags:# need_rating:flags.2?true need_debug:flags.3?true id:long reason:flags.0?PhoneCallDiscardReason duration:flags.1?int = PhoneCall;
+
+phoneConnection#9d4c17c0 id:long ip:string ipv6:string port:int peer_tag:bytes = PhoneConnection;
+
+phoneCallProtocol#a2bb35cb flags:# udp_p2p:flags.0?true udp_reflector:flags.1?true min_layer:int max_layer:int = PhoneCallProtocol;
+
+phone.phoneCall#ec82e140 phone_call:PhoneCall users:Vector<User> = phone.PhoneCall;
+
+upload.cdnFileReuploadNeeded#eea8e46e request_token:bytes = upload.CdnFile;
+upload.cdnFile#a99fca4f bytes:bytes = upload.CdnFile;
+
+cdnPublicKey#c982eaba dc_id:int public_key:string = CdnPublicKey;
+
+cdnConfig#5725e40a public_keys:Vector<CdnPublicKey> = CdnConfig;
+
+langPackString#cad181f6 key:string value:string = LangPackString;
+langPackStringPluralized#6c47ac9f flags:# key:string zero_value:flags.0?string one_value:flags.1?string two_value:flags.2?string few_value:flags.3?string many_value:flags.4?string other_value:string = LangPackString;
+langPackStringDeleted#2979eeb2 key:string = LangPackString;
+
+langPackDifference#f385c1f6 lang_code:string from_version:int version:int strings:Vector<LangPackString> = LangPackDifference;
+
+langPackLanguage#117698f1 name:string native_name:string lang_code:string = LangPackLanguage;
+
+channelAdminRights#5d7ceba5 flags:# change_info:flags.0?true post_messages:flags.1?true edit_messages:flags.2?true delete_messages:flags.3?true ban_users:flags.4?true invite_users:flags.5?true invite_link:flags.6?true pin_messages:flags.7?true add_admins:flags.9?true = ChannelAdminRights;
+
+channelBannedRights#58cf4249 flags:# view_messages:flags.0?true send_messages:flags.1?true send_media:flags.2?true send_stickers:flags.3?true send_gifs:flags.4?true send_games:flags.5?true send_inline:flags.6?true embed_links:flags.7?true until_date:int = ChannelBannedRights;
+
+channelAdminLogEventActionChangeTitle#e6dfb825 prev_value:string new_value:string = ChannelAdminLogEventAction;
+channelAdminLogEventActionChangeAbout#55188a2e prev_value:string new_value:string = ChannelAdminLogEventAction;
+channelAdminLogEventActionChangeUsername#6a4afc38 prev_value:string new_value:string = ChannelAdminLogEventAction;
+channelAdminLogEventActionChangePhoto#b82f55c3 prev_photo:ChatPhoto new_photo:ChatPhoto = ChannelAdminLogEventAction;
+channelAdminLogEventActionToggleInvites#1b7907ae new_value:Bool = ChannelAdminLogEventAction;
+channelAdminLogEventActionToggleSignatures#26ae0971 new_value:Bool = ChannelAdminLogEventAction;
+channelAdminLogEventActionUpdatePinned#e9e82c18 message:Message = ChannelAdminLogEventAction;
+channelAdminLogEventActionEditMessage#709b2405 prev_message:Message new_message:Message = ChannelAdminLogEventAction;
+channelAdminLogEventActionDeleteMessage#42e047bb message:Message = ChannelAdminLogEventAction;
+channelAdminLogEventActionParticipantJoin#183040d3 = ChannelAdminLogEventAction;
+channelAdminLogEventActionParticipantLeave#f89777f2 = ChannelAdminLogEventAction;
+channelAdminLogEventActionParticipantInvite#e31c34d8 participant:ChannelParticipant = ChannelAdminLogEventAction;
+channelAdminLogEventActionParticipantToggleBan#e6d83d7e prev_participant:ChannelParticipant new_participant:ChannelParticipant = ChannelAdminLogEventAction;
+channelAdminLogEventActionParticipantToggleAdmin#d5676710 prev_participant:ChannelParticipant new_participant:ChannelParticipant = ChannelAdminLogEventAction;
+channelAdminLogEventActionChangeStickerSet#b1c3caa7 prev_stickerset:InputStickerSet new_stickerset:InputStickerSet = ChannelAdminLogEventAction;
+channelAdminLogEventActionTogglePreHistoryHidden#5f5c95f1 new_value:Bool = ChannelAdminLogEventAction;
+
+channelAdminLogEvent#3b5a3e40 id:long date:int user_id:int action:ChannelAdminLogEventAction = ChannelAdminLogEvent;
+
+channels.adminLogResults#ed8af74d events:Vector<ChannelAdminLogEvent> chats:Vector<Chat> users:Vector<User> = channels.AdminLogResults;
+
+channelAdminLogEventsFilter#ea107ae4 flags:# join:flags.0?true leave:flags.1?true invite:flags.2?true ban:flags.3?true unban:flags.4?true kick:flags.5?true unkick:flags.6?true promote:flags.7?true demote:flags.8?true info:flags.9?true settings:flags.10?true pinned:flags.11?true edit:flags.12?true delete:flags.13?true = ChannelAdminLogEventsFilter;
+
+popularContact#5ce14175 client_id:long importers:int = PopularContact;
+
+messages.favedStickersNotModified#9e8fa6d3 = messages.FavedStickers;
+messages.favedStickers#f37f2f16 hash:int packs:Vector<StickerPack> stickers:Vector<Document> = messages.FavedStickers;
+
+recentMeUrlUnknown#46e1d13d url:string = RecentMeUrl;
+recentMeUrlUser#8dbc3336 url:string user_id:int = RecentMeUrl;
+recentMeUrlChat#a01b22f9 url:string chat_id:int = RecentMeUrl;
+recentMeUrlChatInvite#eb49081d url:string chat_invite:ChatInvite = RecentMeUrl;
+recentMeUrlStickerSet#bc0a57dc url:string set:StickerSetCovered = RecentMeUrl;
+
+help.recentMeUrls#e0310d7 urls:Vector<RecentMeUrl> chats:Vector<Chat> users:Vector<User> = help.RecentMeUrls;
+
+inputSingleMedia#1cc6e91f flags:# media:InputMedia random_id:long message:string entities:flags.0?Vector<MessageEntity> = InputSingleMedia;
+
+webAuthorization#cac943f2 hash:long bot_id:int domain:string browser:string platform:string date_created:int date_active:int ip:string region:string = WebAuthorization;
+
+account.webAuthorizations#ed56c9fc authorizations:Vector<WebAuthorization> users:Vector<User> = account.WebAuthorizations;
+
+inputMessageID#a676a322 id:int = InputMessage;
+inputMessageReplyTo#bad88395 id:int = InputMessage;
+inputMessagePinned#86872538 = InputMessage;
+
+inputDialogPeer#fcaafeb7 peer:InputPeer = InputDialogPeer;
+
+dialogPeer#e56dbf05 peer:Peer = DialogPeer;
+
+messages.foundStickerSetsNotModified#d54b65d = messages.FoundStickerSets;
+messages.foundStickerSets#5108d648 hash:int sets:Vector<StickerSetCovered> = messages.FoundStickerSets;
+
+fileHash#6242c773 offset:int limit:int hash:bytes = FileHash;
+
+---functions---
+
+invokeAfterMsg#cb9f372d {X:Type} msg_id:long query:!X = X;
+invokeAfterMsgs#3dc4b4f0 {X:Type} msg_ids:Vector<long> query:!X = X;
+initConnection#c7481da6 {X:Type} api_id:int device_model:string system_version:string app_version:string system_lang_code:string lang_pack:string lang_code:string query:!X = X;
+invokeWithLayer#da9b0d0d {X:Type} layer:int query:!X = X;
+invokeWithoutUpdates#bf9459b7 {X:Type} query:!X = X;
+
+auth.checkPhone#6fe51dfb phone_number:string = auth.CheckedPhone;
+auth.sendCode#86aef0ec flags:# allow_flashcall:flags.0?true phone_number:string current_number:flags.0?Bool api_id:int api_hash:string = auth.SentCode;
+auth.signUp#1b067634 phone_number:string phone_code_hash:string phone_code:string first_name:string last_name:string = auth.Authorization;
+auth.signIn#bcd51581 phone_number:string phone_code_hash:string phone_code:string = auth.Authorization;
+auth.logOut#5717da40 = Bool;
+auth.resetAuthorizations#9fab0d1a = Bool;
+auth.sendInvites#771c1d97 phone_numbers:Vector<string> message:string = Bool;
+auth.exportAuthorization#e5bfffcd dc_id:int = auth.ExportedAuthorization;
+auth.importAuthorization#e3ef9613 id:int bytes:bytes = auth.Authorization;
+auth.bindTempAuthKey#cdd42a05 perm_auth_key_id:long nonce:long expires_at:int encrypted_message:bytes = Bool;
+auth.importBotAuthorization#67a3ff2c flags:int api_id:int api_hash:string bot_auth_token:string = auth.Authorization;
+auth.checkPassword#a63011e password_hash:bytes = auth.Authorization;
+auth.requestPasswordRecovery#d897bc66 = auth.PasswordRecovery;
+auth.recoverPassword#4ea56e92 code:string = auth.Authorization;
+auth.resendCode#3ef1a9bf phone_number:string phone_code_hash:string = auth.SentCode;
+auth.cancelCode#1f040578 phone_number:string phone_code_hash:string = Bool;
+auth.dropTempAuthKeys#8e48a188 except_auth_keys:Vector<long> = Bool;
+
+account.registerDevice#5cbea590 token_type:int token:string app_sandbox:Bool secret:bytes other_uids:Vector<int> = Bool;
+account.unregisterDevice#3076c4bf token_type:int token:string other_uids:Vector<int> = Bool;
+account.updateNotifySettings#84be5b93 peer:InputNotifyPeer settings:InputPeerNotifySettings = Bool;
+account.getNotifySettings#12b3ad31 peer:InputNotifyPeer = PeerNotifySettings;
+account.resetNotifySettings#db7e1747 = Bool;
+account.updateProfile#78515775 flags:# first_name:flags.0?string last_name:flags.1?string about:flags.2?string = User;
+account.updateStatus#6628562c offline:Bool = Bool;
+account.getWallPapers#c04cfac2 = Vector<WallPaper>;
+account.reportPeer#ae189d5f peer:InputPeer reason:ReportReason = Bool;
+account.checkUsername#2714d86c username:string = Bool;
+account.updateUsername#3e0bdd7c username:string = User;
+account.getPrivacy#dadbc950 key:InputPrivacyKey = account.PrivacyRules;
+account.setPrivacy#c9f81ce8 key:InputPrivacyKey rules:Vector<InputPrivacyRule> = account.PrivacyRules;
+account.deleteAccount#418d4e0b reason:string = Bool;
+account.getAccountTTL#8fc711d = AccountDaysTTL;
+account.setAccountTTL#2442485e ttl:AccountDaysTTL = Bool;
+account.sendChangePhoneCode#8e57deb flags:# allow_flashcall:flags.0?true phone_number:string current_number:flags.0?Bool = auth.SentCode;
+account.changePhone#70c32edb phone_number:string phone_code_hash:string phone_code:string = User;
+account.updateDeviceLocked#38df3532 period:int = Bool;
+account.getAuthorizations#e320c158 = account.Authorizations;
+account.resetAuthorization#df77f3bc hash:long = Bool;
+account.getPassword#548a30f5 = account.Password;
+account.getPasswordSettings#bc8d11bb current_password_hash:bytes = account.PasswordSettings;
+account.updatePasswordSettings#fa7c4b86 current_password_hash:bytes new_settings:account.PasswordInputSettings = Bool;
+account.sendConfirmPhoneCode#1516d7bd flags:# allow_flashcall:flags.0?true hash:string current_number:flags.0?Bool = auth.SentCode;
+account.confirmPhone#5f2178c3 phone_code_hash:string phone_code:string = Bool;
+account.getTmpPassword#4a82327e password_hash:bytes period:int = account.TmpPassword;
+account.getWebAuthorizations#182e6d6f = account.WebAuthorizations;
+account.resetWebAuthorization#2d01b9ef hash:long = Bool;
+account.resetWebAuthorizations#682d2594 = Bool;
+
+users.getUsers#d91a548 id:Vector<InputUser> = Vector<User>;
+users.getFullUser#ca30a5b1 id:InputUser = UserFull;
+
+contacts.getStatuses#c4a353ee = Vector<ContactStatus>;
+contacts.getContacts#c023849f hash:int = contacts.Contacts;
+contacts.importContacts#2c800be5 contacts:Vector<InputContact> = contacts.ImportedContacts;
+contacts.deleteContact#8e953744 id:InputUser = contacts.Link;
+contacts.deleteContacts#59ab389e id:Vector<InputUser> = Bool;
+contacts.block#332b49fc id:InputUser = Bool;
+contacts.unblock#e54100bd id:InputUser = Bool;
+contacts.getBlocked#f57c350f offset:int limit:int = contacts.Blocked;
+contacts.exportCard#84e53737 = Vector<int>;
+contacts.importCard#4fe196fe export_card:Vector<int> = User;
+contacts.search#11f812d8 q:string limit:int = contacts.Found;
+contacts.resolveUsername#f93ccba3 username:string = contacts.ResolvedPeer;
+contacts.getTopPeers#d4982db5 flags:# correspondents:flags.0?true bots_pm:flags.1?true bots_inline:flags.2?true phone_calls:flags.3?true groups:flags.10?true channels:flags.15?true offset:int limit:int hash:int = contacts.TopPeers;
+contacts.resetTopPeerRating#1ae373ac category:TopPeerCategory peer:InputPeer = Bool;
+contacts.resetSaved#879537f1 = Bool;
+
+messages.getMessages#63c66506 id:Vector<InputMessage> = messages.Messages;
+messages.getDialogs#191ba9c5 flags:# exclude_pinned:flags.0?true offset_date:int offset_id:int offset_peer:InputPeer limit:int = messages.Dialogs;
+messages.getHistory#dcbb8260 peer:InputPeer offset_id:int offset_date:int add_offset:int limit:int max_id:int min_id:int hash:int = messages.Messages;
+messages.search#8614ef68 flags:# peer:InputPeer q:string from_id:flags.0?InputUser filter:MessagesFilter min_date:int max_date:int offset_id:int add_offset:int limit:int max_id:int min_id:int hash:int = messages.Messages;
+messages.readHistory#e306d3a peer:InputPeer max_id:int = messages.AffectedMessages;
+messages.deleteHistory#1c015b09 flags:# just_clear:flags.0?true peer:InputPeer max_id:int = messages.AffectedHistory;
+messages.deleteMessages#e58e95d2 flags:# revoke:flags.0?true id:Vector<int> = messages.AffectedMessages;
+messages.receivedMessages#5a954c0 max_id:int = Vector<ReceivedNotifyMessage>;
+messages.setTyping#a3825e50 peer:InputPeer action:SendMessageAction = Bool;
+messages.sendMessage#fa88427a flags:# no_webpage:flags.1?true silent:flags.5?true background:flags.6?true clear_draft:flags.7?true peer:InputPeer reply_to_msg_id:flags.0?int message:string random_id:long reply_markup:flags.2?ReplyMarkup entities:flags.3?Vector<MessageEntity> = Updates;
+messages.sendMedia#b8d1262b flags:# silent:flags.5?true background:flags.6?true clear_draft:flags.7?true peer:InputPeer reply_to_msg_id:flags.0?int media:InputMedia message:string random_id:long reply_markup:flags.2?ReplyMarkup entities:flags.3?Vector<MessageEntity> = Updates;
+messages.forwardMessages#708e0195 flags:# silent:flags.5?true background:flags.6?true with_my_score:flags.8?true grouped:flags.9?true from_peer:InputPeer id:Vector<int> random_id:Vector<long> to_peer:InputPeer = Updates;
+messages.reportSpam#cf1592db peer:InputPeer = Bool;
+messages.hideReportSpam#a8f1709b peer:InputPeer = Bool;
+messages.getPeerSettings#3672e09c peer:InputPeer = PeerSettings;
+messages.report#bd82b658 peer:InputPeer id:Vector<int> reason:ReportReason = Bool;
+messages.getChats#3c6aa187 id:Vector<int> = messages.Chats;
+messages.getFullChat#3b831c66 chat_id:int = messages.ChatFull;
+messages.editChatTitle#dc452855 chat_id:int title:string = Updates;
+messages.editChatPhoto#ca4c79d8 chat_id:int photo:InputChatPhoto = Updates;
+messages.addChatUser#f9a0aa09 chat_id:int user_id:InputUser fwd_limit:int = Updates;
+messages.deleteChatUser#e0611f16 chat_id:int user_id:InputUser = Updates;
+messages.createChat#9cb126e users:Vector<InputUser> title:string = Updates;
+messages.getDhConfig#26cf8950 version:int random_length:int = messages.DhConfig;
+messages.requestEncryption#f64daf43 user_id:InputUser random_id:int g_a:bytes = EncryptedChat;
+messages.acceptEncryption#3dbc0415 peer:InputEncryptedChat g_b:bytes key_fingerprint:long = EncryptedChat;
+messages.discardEncryption#edd923c5 chat_id:int = Bool;
+messages.setEncryptedTyping#791451ed peer:InputEncryptedChat typing:Bool = Bool;
+messages.readEncryptedHistory#7f4b690a peer:InputEncryptedChat max_date:int = Bool;
+messages.sendEncrypted#a9776773 peer:InputEncryptedChat random_id:long data:bytes = messages.SentEncryptedMessage;
+messages.sendEncryptedFile#9a901b66 peer:InputEncryptedChat random_id:long data:bytes file:InputEncryptedFile = messages.SentEncryptedMessage;
+messages.sendEncryptedService#32d439a4 peer:InputEncryptedChat random_id:long data:bytes = messages.SentEncryptedMessage;
+messages.receivedQueue#55a5bb66 max_qts:int = Vector<long>;
+messages.reportEncryptedSpam#4b0c8c0f peer:InputEncryptedChat = Bool;
+messages.readMessageContents#36a73f77 id:Vector<int> = messages.AffectedMessages;
+messages.getStickers#85cb5182 flags:# exclude_featured:flags.0?true emoticon:string hash:string = messages.Stickers;
+messages.getAllStickers#1c9618b1 hash:int = messages.AllStickers;
+messages.getWebPagePreview#8b68b0cc flags:# message:string entities:flags.3?Vector<MessageEntity> = MessageMedia;
+messages.exportChatInvite#7d885289 chat_id:int = ExportedChatInvite;
+messages.checkChatInvite#3eadb1bb hash:string = ChatInvite;
+messages.importChatInvite#6c50051c hash:string = Updates;
+messages.getStickerSet#2619a90e stickerset:InputStickerSet = messages.StickerSet;
+messages.installStickerSet#c78fe460 stickerset:InputStickerSet archived:Bool = messages.StickerSetInstallResult;
+messages.uninstallStickerSet#f96e55de stickerset:InputStickerSet = Bool;
+messages.startBot#e6df7378 bot:InputUser peer:InputPeer random_id:long start_param:string = Updates;
+messages.getMessagesViews#c4c8a55d peer:InputPeer id:Vector<int> increment:Bool = Vector<int>;
+messages.toggleChatAdmins#ec8bd9e1 chat_id:int enabled:Bool = Updates;
+messages.editChatAdmin#a9e69f2e chat_id:int user_id:InputUser is_admin:Bool = Bool;
+messages.migrateChat#15a3b8e3 chat_id:int = Updates;
+messages.searchGlobal#9e3cacb0 q:string offset_date:int offset_peer:InputPeer offset_id:int limit:int = messages.Messages;
+messages.reorderStickerSets#78337739 flags:# masks:flags.0?true order:Vector<long> = Bool;
+messages.getDocumentByHash#338e2464 sha256:bytes size:int mime_type:string = Document;
+messages.searchGifs#bf9a776b q:string offset:int = messages.FoundGifs;
+messages.getSavedGifs#83bf3d52 hash:int = messages.SavedGifs;
+messages.saveGif#327a30cb id:InputDocument unsave:Bool = Bool;
+messages.getInlineBotResults#514e999d flags:# bot:InputUser peer:InputPeer geo_point:flags.0?InputGeoPoint query:string offset:string = messages.BotResults;
+messages.setInlineBotResults#eb5ea206 flags:# gallery:flags.0?true private:flags.1?true query_id:long results:Vector<InputBotInlineResult> cache_time:int next_offset:flags.2?string switch_pm:flags.3?InlineBotSwitchPM = Bool;
+messages.sendInlineBotResult#b16e06fe flags:# silent:flags.5?true background:flags.6?true clear_draft:flags.7?true peer:InputPeer reply_to_msg_id:flags.0?int random_id:long query_id:long id:string = Updates;
+messages.getMessageEditData#fda68d36 peer:InputPeer id:int = messages.MessageEditData;
+messages.editMessage#5d1b8dd flags:# no_webpage:flags.1?true stop_geo_live:flags.12?true peer:InputPeer id:int message:flags.11?string reply_markup:flags.2?ReplyMarkup entities:flags.3?Vector<MessageEntity> geo_point:flags.13?InputGeoPoint = Updates;
+messages.editInlineBotMessage#b0e08243 flags:# no_webpage:flags.1?true stop_geo_live:flags.12?true id:InputBotInlineMessageID message:flags.11?string reply_markup:flags.2?ReplyMarkup entities:flags.3?Vector<MessageEntity> geo_point:flags.13?InputGeoPoint = Bool;
+messages.getBotCallbackAnswer#810a9fec flags:# game:flags.1?true peer:InputPeer msg_id:int data:flags.0?bytes = messages.BotCallbackAnswer;
+messages.setBotCallbackAnswer#d58f130a flags:# alert:flags.1?true query_id:long message:flags.0?string url:flags.2?string cache_time:int = Bool;
+messages.getPeerDialogs#e470bcfd peers:Vector<InputDialogPeer> = messages.PeerDialogs;
+messages.saveDraft#bc39e14b flags:# no_webpage:flags.1?true reply_to_msg_id:flags.0?int peer:InputPeer message:string entities:flags.3?Vector<MessageEntity> = Bool;
+messages.getAllDrafts#6a3f8d65 = Updates;
+messages.getFeaturedStickers#2dacca4f hash:int = messages.FeaturedStickers;
+messages.readFeaturedStickers#5b118126 id:Vector<long> = Bool;
+messages.getRecentStickers#5ea192c9 flags:# attached:flags.0?true hash:int = messages.RecentStickers;
+messages.saveRecentSticker#392718f8 flags:# attached:flags.0?true id:InputDocument unsave:Bool = Bool;
+messages.clearRecentStickers#8999602d flags:# attached:flags.0?true = Bool;
+messages.getArchivedStickers#57f17692 flags:# masks:flags.0?true offset_id:long limit:int = messages.ArchivedStickers;
+messages.getMaskStickers#65b8c79f hash:int = messages.AllStickers;
+messages.getAttachedStickers#cc5b67cc media:InputStickeredMedia = Vector<StickerSetCovered>;
+messages.setGameScore#8ef8ecc0 flags:# edit_message:flags.0?true force:flags.1?true peer:InputPeer id:int user_id:InputUser score:int = Updates;
+messages.setInlineGameScore#15ad9f64 flags:# edit_message:flags.0?true force:flags.1?true id:InputBotInlineMessageID user_id:InputUser score:int = Bool;
+messages.getGameHighScores#e822649d peer:InputPeer id:int user_id:InputUser = messages.HighScores;
+messages.getInlineGameHighScores#f635e1b id:InputBotInlineMessageID user_id:InputUser = messages.HighScores;
+messages.getCommonChats#d0a48c4 user_id:InputUser max_id:int limit:int = messages.Chats;
+messages.getAllChats#eba80ff0 except_ids:Vector<int> = messages.Chats;
+messages.getWebPage#32ca8f91 url:string hash:int = WebPage;
+messages.toggleDialogPin#a731e257 flags:# pinned:flags.0?true peer:InputDialogPeer = Bool;
+messages.reorderPinnedDialogs#5b51d63f flags:# force:flags.0?true order:Vector<InputDialogPeer> = Bool;
+messages.getPinnedDialogs#e254d64e = messages.PeerDialogs;
+messages.setBotShippingResults#e5f672fa flags:# query_id:long error:flags.0?string shipping_options:flags.1?Vector<ShippingOption> = Bool;
+messages.setBotPrecheckoutResults#9c2dd95 flags:# success:flags.1?true query_id:long error:flags.0?string = Bool;
+messages.uploadMedia#519bc2b1 peer:InputPeer media:InputMedia = MessageMedia;
+messages.sendScreenshotNotification#c97df020 peer:InputPeer reply_to_msg_id:int random_id:long = Updates;
+messages.getFavedStickers#21ce0b0e hash:int = messages.FavedStickers;
+messages.faveSticker#b9ffc55b id:InputDocument unfave:Bool = Bool;
+messages.getUnreadMentions#46578472 peer:InputPeer offset_id:int add_offset:int limit:int max_id:int min_id:int = messages.Messages;
+messages.readMentions#f0189d3 peer:InputPeer = messages.AffectedHistory;
+messages.getRecentLocations#bbc45b09 peer:InputPeer limit:int hash:int = messages.Messages;
+messages.sendMultiMedia#2095512f flags:# silent:flags.5?true background:flags.6?true clear_draft:flags.7?true peer:InputPeer reply_to_msg_id:flags.0?int multi_media:Vector<InputSingleMedia> = Updates;
+messages.uploadEncryptedFile#5057c497 peer:InputEncryptedChat file:InputEncryptedFile = EncryptedFile;
+messages.searchStickerSets#c2b7d08b flags:# exclude_featured:flags.0?true q:string hash:int = messages.FoundStickerSets;
+
+updates.getState#edd4882a = updates.State;
+updates.getDifference#25939651 flags:# pts:int pts_total_limit:flags.0?int date:int qts:int = updates.Difference;
+updates.getChannelDifference#3173d78 flags:# force:flags.0?true channel:InputChannel filter:ChannelMessagesFilter pts:int limit:int = updates.ChannelDifference;
+
+photos.updateProfilePhoto#f0bb5152 id:InputPhoto = UserProfilePhoto;
+photos.uploadProfilePhoto#4f32c098 file:InputFile = photos.Photo;
+photos.deletePhotos#87cf7f2f id:Vector<InputPhoto> = Vector<long>;
+photos.getUserPhotos#91cd32a8 user_id:InputUser offset:int max_id:long limit:int = photos.Photos;
+
+upload.saveFilePart#b304a621 file_id:long file_part:int bytes:bytes = Bool;
+upload.getFile#e3a6cfb5 location:InputFileLocation offset:int limit:int = upload.File;
+upload.saveBigFilePart#de7b673d file_id:long file_part:int file_total_parts:int bytes:bytes = Bool;
+upload.getWebFile#24e6818d location:InputWebFileLocation offset:int limit:int = upload.WebFile;
+upload.getCdnFile#2000bcc3 file_token:bytes offset:int limit:int = upload.CdnFile;
+upload.reuploadCdnFile#9b2754a8 file_token:bytes request_token:bytes = Vector<FileHash>;
+upload.getCdnFileHashes#4da54231 file_token:bytes offset:int = Vector<FileHash>;
+upload.getFileHashes#c7025931 location:InputFileLocation offset:int = Vector<FileHash>;
+
+help.getConfig#c4f9186b = Config;
+help.getNearestDc#1fb33026 = NearestDc;
+help.getAppUpdate#ae2de196 = help.AppUpdate;
+help.saveAppLog#6f02f748 events:Vector<InputAppEvent> = Bool;
+help.getInviteText#4d392343 = help.InviteText;
+help.getSupport#9cdf08cd = help.Support;
+help.getAppChangelog#9010ef6f prev_app_version:string = Updates;
+help.getTermsOfService#350170f3 = help.TermsOfService;
+help.setBotUpdatesStatus#ec22cfcd pending_updates_count:int message:string = Bool;
+help.getCdnConfig#52029342 = CdnConfig;
+help.getRecentMeUrls#3dc0f114 referer:string = help.RecentMeUrls;
+
+channels.readHistory#cc104937 channel:InputChannel max_id:int = Bool;
+channels.deleteMessages#84c1fd4e channel:InputChannel id:Vector<int> = messages.AffectedMessages;
+channels.deleteUserHistory#d10dd71b channel:InputChannel user_id:InputUser = messages.AffectedHistory;
+channels.reportSpam#fe087810 channel:InputChannel user_id:InputUser id:Vector<int> = Bool;
+channels.getMessages#ad8c9a23 channel:InputChannel id:Vector<InputMessage> = messages.Messages;
+channels.getParticipants#123e05e9 channel:InputChannel filter:ChannelParticipantsFilter offset:int limit:int hash:int = channels.ChannelParticipants;
+channels.getParticipant#546dd7a6 channel:InputChannel user_id:InputUser = channels.ChannelParticipant;
+channels.getChannels#a7f6bbb id:Vector<InputChannel> = messages.Chats;
+channels.getFullChannel#8736a09 channel:InputChannel = messages.ChatFull;
+channels.createChannel#f4893d7f flags:# broadcast:flags.0?true megagroup:flags.1?true title:string about:string = Updates;
+channels.editAbout#13e27f1e channel:InputChannel about:string = Bool;
+channels.editAdmin#20b88214 channel:InputChannel user_id:InputUser admin_rights:ChannelAdminRights = Updates;
+channels.editTitle#566decd0 channel:InputChannel title:string = Updates;
+channels.editPhoto#f12e57c9 channel:InputChannel photo:InputChatPhoto = Updates;
+channels.checkUsername#10e6bd2c channel:InputChannel username:string = Bool;
+channels.updateUsername#3514b3de channel:InputChannel username:string = Bool;
+channels.joinChannel#24b524c5 channel:InputChannel = Updates;
+channels.leaveChannel#f836aa95 channel:InputChannel = Updates;
+channels.inviteToChannel#199f3a6c channel:InputChannel users:Vector<InputUser> = Updates;
+channels.exportInvite#c7560885 channel:InputChannel = ExportedChatInvite;
+channels.deleteChannel#c0111fe3 channel:InputChannel = Updates;
+channels.toggleInvites#49609307 channel:InputChannel enabled:Bool = Updates;
+channels.exportMessageLink#ceb77163 channel:InputChannel id:int grouped:Bool = ExportedMessageLink;
+channels.toggleSignatures#1f69b606 channel:InputChannel enabled:Bool = Updates;
+channels.updatePinnedMessage#a72ded52 flags:# silent:flags.0?true channel:InputChannel id:int = Updates;
+channels.getAdminedPublicChannels#8d8d82d7 = messages.Chats;
+channels.editBanned#bfd915cd channel:InputChannel user_id:InputUser banned_rights:ChannelBannedRights = Updates;
+channels.getAdminLog#33ddf480 flags:# channel:InputChannel q:string events_filter:flags.0?ChannelAdminLogEventsFilter admins:flags.1?Vector<InputUser> max_id:long min_id:long limit:int = channels.AdminLogResults;
+channels.setStickers#ea8ca4f9 channel:InputChannel stickerset:InputStickerSet = Bool;
+channels.readMessageContents#eab5dc38 channel:InputChannel id:Vector<int> = Bool;
+channels.deleteHistory#af369d42 channel:InputChannel max_id:int = Bool;
+channels.togglePreHistoryHidden#eabbb94c channel:InputChannel enabled:Bool = Updates;
+
+bots.sendCustomRequest#aa2769ed custom_method:string params:DataJSON = DataJSON;
+bots.answerWebhookJSONQuery#e6213f4d query_id:long data:DataJSON = Bool;
+
+payments.getPaymentForm#99f09745 msg_id:int = payments.PaymentForm;
+payments.getPaymentReceipt#a092a980 msg_id:int = payments.PaymentReceipt;
+payments.validateRequestedInfo#770a8e74 flags:# save:flags.0?true msg_id:int info:PaymentRequestedInfo = payments.ValidatedRequestedInfo;
+payments.sendPaymentForm#2b8879b3 flags:# msg_id:int requested_info_id:flags.0?string shipping_option_id:flags.1?string credentials:InputPaymentCredentials = payments.PaymentResult;
+payments.getSavedInfo#227d824b = payments.SavedInfo;
+payments.clearSavedInfo#d83d70c1 flags:# credentials:flags.0?true info:flags.1?true = Bool;
+
+stickers.createStickerSet#9bd86e6a flags:# masks:flags.0?true user_id:InputUser title:string short_name:string stickers:Vector<InputStickerSetItem> = messages.StickerSet;
+stickers.removeStickerFromSet#f7760f51 sticker:InputDocument = messages.StickerSet;
+stickers.changeStickerPosition#ffb6d4ca sticker:InputDocument position:int = messages.StickerSet;
+stickers.addStickerToSet#8653febe stickerset:InputStickerSet sticker:InputStickerSetItem = messages.StickerSet;
+
+phone.getCallConfig#55451fa9 = DataJSON;
+phone.requestCall#5b95b3d4 user_id:InputUser random_id:int g_a_hash:bytes protocol:PhoneCallProtocol = phone.PhoneCall;
+phone.acceptCall#3bd2b4a0 peer:InputPhoneCall g_b:bytes protocol:PhoneCallProtocol = phone.PhoneCall;
+phone.confirmCall#2efe1722 peer:InputPhoneCall g_a:bytes key_fingerprint:long protocol:PhoneCallProtocol = phone.PhoneCall;
+phone.receivedCall#17d54f61 peer:InputPhoneCall = Bool;
+phone.discardCall#78d413a6 peer:InputPhoneCall duration:int reason:PhoneCallDiscardReason connection_id:long = Updates;
+phone.setCallRating#1c536a34 peer:InputPhoneCall rating:int comment:string = Updates;
+phone.saveCallDebug#277add7e peer:InputPhoneCall debug:DataJSON = Bool;
+
+langpack.getLangPack#9ab5c58e lang_code:string = LangPackDifference;
+langpack.getStrings#2e1ee318 lang_code:string keys:Vector<string> = Vector<LangPackString>;
+langpack.getDifference#b2e4d7d from_version:int = LangPackDifference;
+langpack.getLanguages#800fd57d = Vector<LangPackLanguage>;
diff --git a/libs/tdlib/td/td/generate/scheme/telegram_api.tlo b/libs/tdlib/td/td/generate/scheme/telegram_api.tlo
new file mode 100644
index 0000000000..6557f4c0fd
--- /dev/null
+++ b/libs/tdlib/td/td/generate/scheme/telegram_api.tlo
diff --git a/libs/tdlib/td/td/generate/scheme/update-tlo.sh b/libs/tdlib/td/td/generate/scheme/update-tlo.sh
new file mode 100644
index 0000000000..cfcb71f35c
--- /dev/null
+++ b/libs/tdlib/td/td/generate/scheme/update-tlo.sh
@@ -0,0 +1,6 @@
+#!/bin/sh
+cd $(dirname $0)
+tl-parser -e td_api.tlo td_api.tl
+tl-parser -e telegram_api.tlo telegram_api.tl
+tl-parser -e mtproto_api.tlo mtproto_api.tl
+tl-parser -e secret_api.tlo secret_api.tl
diff --git a/libs/tdlib/td/td/generate/tl_json_converter.cpp b/libs/tdlib/td/td/generate/tl_json_converter.cpp
new file mode 100644
index 0000000000..3fda1152cd
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_json_converter.cpp
@@ -0,0 +1,224 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_json_converter.h"
+
+#include "td/tl/tl_simple.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/filesystem.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/StringBuilder.h"
+
+#include <utility>
+
+namespace td {
+
+template <class T>
+void gen_to_json_constructor(StringBuilder &sb, const T *constructor, bool is_header) {
+  sb << "void to_json(JsonValueScope &jv, "
+     << "const td_api::" << tl::simple::gen_cpp_name(constructor->name) << " &object)";
+  if (is_header) {
+    sb << ";\n";
+    return;
+  }
+  sb << " {\n";
+  sb << "  auto jo = jv.enter_object();\n";
+  sb << "  jo << ctie(\"@type\", \"" << tl::simple::gen_cpp_name(constructor->name) << "\");\n";
+  for (auto &arg : constructor->args) {
+    auto field = tl::simple::gen_cpp_field_name(arg.name);
+    // TODO: or as null
+    bool is_custom = arg.type->type == tl::simple::Type::Custom;
+
+    if (is_custom) {
+      sb << "  if (object." << field << ") {\n  ";
+    }
+    auto object = PSTRING() << "object." << tl::simple::gen_cpp_field_name(arg.name);
+    if (arg.type->type == tl::simple::Type::Bytes) {
+      object = PSTRING() << "base64_encode(" << object << ")";
+    } else if (arg.type->type == tl::simple::Type::Int64) {
+      object = PSTRING() << "JsonInt64{" << object << "}";
+    } else if (arg.type->type == tl::simple::Type::Vector &&
+               arg.type->vector_value_type->type == tl::simple::Type::Int64) {
+      object = PSTRING() << "JsonVectorInt64{" << object << "}";
+    }
+    sb << "  jo << ctie(\"" << arg.name << "\", ToJson(" << object << "));\n";
+    if (is_custom) {
+      sb << "  }\n";
+    }
+  }
+  sb << "}\n";
+}
+
+void gen_to_json(StringBuilder &sb, const tl::simple::Schema &schema, bool is_header) {
+  for (auto *custom_type : schema.custom_types) {
+    if (custom_type->constructors.size() > 1) {
+      auto type_name = tl::simple::gen_cpp_name(custom_type->name);
+      sb << "void to_json(JsonValueScope &jv, const td_api::" << type_name << " &object)";
+      if (is_header) {
+        sb << ";\n";
+      } else {
+        sb << " {\n"
+           << "  td_api::downcast_call(const_cast<td_api::" << type_name
+           << " &>(object), [&jv](const auto &object) { "
+              "to_json(jv, object); });\n"
+           << "}\n";
+      }
+    }
+    for (auto *constructor : custom_type->constructors) {
+      gen_to_json_constructor(sb, constructor, is_header);
+    }
+  }
+  for (auto *function : schema.functions) {
+    gen_to_json_constructor(sb, function, is_header);
+  }
+}
+
+template <class T>
+void gen_from_json_constructor(StringBuilder &sb, const T *constructor, bool is_header) {
+  sb << "Status from_json(td_api::" << tl::simple::gen_cpp_name(constructor->name) << " &to, JsonObject &from)";
+  if (is_header) {
+    sb << ";\n";
+  } else {
+    sb << " {\n";
+    for (auto &arg : constructor->args) {
+      sb << "  {\n";
+      sb << "    TRY_RESULT(value, get_json_object_field(from, \"" << tl::simple::gen_cpp_name(arg.name)
+         << "\", JsonValue::Type::Null, true));\n";
+      sb << "    if (value.type() != JsonValue::Type::Null) {\n";
+      if (arg.type->type == tl::simple::Type::Bytes) {
+        sb << "      TRY_STATUS(from_json_bytes(to." << tl::simple::gen_cpp_field_name(arg.name) << ", value));\n";
+      } else {
+        sb << "      TRY_STATUS(from_json(to." << tl::simple::gen_cpp_field_name(arg.name) << ", value));\n";
+      }
+      sb << "    }\n";
+      sb << "  }\n";
+    }
+    sb << "  return Status::OK();\n";
+    sb << "}\n";
+  }
+}
+
+void gen_from_json(StringBuilder &sb, const tl::simple::Schema &schema, bool is_header) {
+  for (auto *custom_type : schema.custom_types) {
+    for (auto *constructor : custom_type->constructors) {
+      gen_from_json_constructor(sb, constructor, is_header);
+    }
+  }
+  for (auto *function : schema.functions) {
+    gen_from_json_constructor(sb, function, is_header);
+  }
+}
+
+using Vec = std::vector<std::pair<int32, std::string>>;
+void gen_tl_constructor_from_string(StringBuilder &sb, Slice name, const Vec &vec, bool is_header) {
+  sb << "Result<int32> tl_constructor_from_string(td_api::" << name << " *object, const std::string &str)";
+  if (is_header) {
+    sb << ";\n";
+    return;
+  }
+  sb << " {\n";
+  sb << "  static const std::unordered_map<Slice, int32, SliceHash> m = {\n";
+
+  bool is_first = true;
+  for (auto &p : vec) {
+    if (is_first) {
+      is_first = false;
+    } else {
+      sb << ",\n";
+    }
+    sb << "    {\"" << p.second << "\", " << p.first << "}";
+  }
+  sb << "\n  };\n";
+  sb << "  auto it = m.find(str);\n";
+  sb << "  if (it == m.end()) {\n"
+     << "    return Status::Error(\"Unknown class\");\n"
+     << "  }\n"
+     << "  return it->second;\n";
+  sb << "}\n";
+}
+
+void gen_tl_constructor_from_string(StringBuilder &sb, const tl::simple::Schema &schema, bool is_header) {
+  Vec vec_for_nullary;
+  for (auto *custom_type : schema.custom_types) {
+    Vec vec;
+    for (auto *constructor : custom_type->constructors) {
+      vec.push_back(std::make_pair(constructor->id, constructor->name));
+      vec_for_nullary.push_back(vec.back());
+    }
+
+    if (vec.size() > 1) {
+      gen_tl_constructor_from_string(sb, tl::simple::gen_cpp_name(custom_type->name), vec, is_header);
+    }
+  }
+  gen_tl_constructor_from_string(sb, "Object", vec_for_nullary, is_header);
+
+  Vec vec_for_function;
+  for (auto *function : schema.functions) {
+    vec_for_function.push_back(std::make_pair(function->id, function->name));
+  }
+  gen_tl_constructor_from_string(sb, "Function", vec_for_function, is_header);
+}
+
+void gen_json_converter_file(const tl::simple::Schema &schema, const std::string &file_name_base, bool is_header) {
+  auto file_name = is_header ? file_name_base + ".h" : file_name_base + ".cpp";
+  file_name = "auto/" + file_name;
+  auto old_file_content = [&] {
+    auto r_content = read_file(file_name);
+    if (r_content.is_error()) {
+      return BufferSlice();
+    }
+    return r_content.move_as_ok();
+  }();
+
+  std::string buf(2000000, ' ');
+  StringBuilder sb(buf);
+
+  if (is_header) {
+    sb << "#pragma once\n\n";
+
+    sb << "#include \"td/telegram/td_api.h\"\n\n";
+
+    sb << "#include \"td/utils/JsonBuilder.h\"\n";
+    sb << "#include \"td/utils/Status.h\"\n\n";
+  } else {
+    sb << "#include \"" << file_name_base << ".h\"\n\n";
+
+    sb << "#include \"td/telegram/td_api.h\"\n";
+    sb << "#include \"td/telegram/td_api.hpp\"\n\n";
+
+    sb << "#include \"td/tl/tl_json.h\"\n\n";
+
+    sb << "#include \"td/utils/base64.h\"\n";
+    sb << "#include \"td/utils/common.h\"\n";
+    sb << "#include \"td/utils/Slice.h\"\n\n";
+
+    sb << "#include <unordered_map>\n\n";
+  }
+  sb << "namespace td {\n";
+  sb << "namespace td_api{\n";
+  gen_tl_constructor_from_string(sb, schema, is_header);
+  gen_from_json(sb, schema, is_header);
+  gen_to_json(sb, schema, is_header);
+  sb << "}  // namespace td_api\n";
+  sb << "}  // namespace td\n";
+
+  CHECK(!sb.is_error());
+  buf.resize(sb.as_cslice().size());
+  auto new_file_content = std::move(buf);
+  if (new_file_content != old_file_content.as_slice()) {
+    write_file(file_name, new_file_content).ensure();
+  }
+}
+
+void gen_json_converter(const tl::tl_config &config, const std::string &file_name) {
+  tl::simple::Schema schema(config);
+  gen_json_converter_file(schema, file_name, true);
+  gen_json_converter_file(schema, file_name, false);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_json_converter.h b/libs/tdlib/td/td/generate/tl_json_converter.h
new file mode 100644
index 0000000000..719ff451f0
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_json_converter.h
@@ -0,0 +1,17 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/tl/tl_config.h"
+
+#include <string>
+
+namespace td {
+
+void gen_json_converter(const tl::tl_config &config, const std::string &file_name);
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_writer_c.h b/libs/tdlib/td/td/generate/tl_writer_c.h
new file mode 100644
index 0000000000..9402bae72f
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_writer_c.h
@@ -0,0 +1,1357 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/tl/tl_writer.h"
+
+#include <cassert>
+#include <cstdint>
+#include <sstream>
+#include <string>
+#include <vector>
+
+namespace td {
+
+class TlWriterCCommon : public tl::TL_writer {
+ public:
+  int is_header_;
+  std::string prefix_;
+  TlWriterCCommon(const std::string &name, int is_header, const std::string &prefix = "")
+      : TL_writer(name), is_header_(is_header), prefix_(prefix) {
+  }
+
+  int get_max_arity() const override {
+    return 0;
+  }
+
+  bool is_built_in_simple_type(const std::string &name) const override {
+    return name == "Bool" || name == "Int32" || name == "Int53" || name == "Int64" || name == "Double" ||
+           name == "String" || name == "Bytes";
+  }
+  bool is_built_in_complex_type(const std::string &name) const override {
+    return name == "Vector";
+  }
+  bool is_type_bare(const tl::tl_type *t) const override {
+    return t->simple_constructors <= 1 || (is_built_in_simple_type(t->name) && t->name != "Bool") ||
+           is_built_in_complex_type(t->name);
+  }
+
+  std::vector<std::string> get_parsers() const override {
+    return {};
+  }
+  int get_parser_type(const tl::tl_combinator *t, const std::string &name) const override {
+    return 0;
+  }
+  std::vector<std::string> get_storers() const override {
+    return {};
+  }
+  std::vector<std::string> get_additional_functions() const override {
+    return {"TdConvertToInternal", "TdConvertFromInternal", "TdSerialize",    "TdToString",
+            "TdDestroyObject",     "TdStackStorer",         "TdStackFetcher", "enum"};
+  }
+  int get_storer_type(const tl::tl_combinator *t, const std::string &name) const override {
+    return name == "to_string" || name == "to_cpp_string";
+  }
+
+  std::string gen_base_tl_class_name() const override {
+    return "Object";
+  }
+  std::string gen_base_type_class_name(int arity) const override {
+    assert(arity == 0);
+    return "Object";
+  }
+  std::string gen_base_function_class_name() const override {
+    return "Function";
+  }
+
+  static std::string to_camelCase(const std::string &name) {
+    return to_cCamelCase(name, false);
+  }
+  static std::string to_CamelCase(const std::string &name) {
+    return to_cCamelCase(name, true);
+  }
+  static std::string to_cCamelCase(const std::string &name, bool flag) {
+    bool next_to_upper = flag;
+    std::string result;
+    for (std::size_t i = 0; i < name.size(); i++) {
+      if (!is_alnum(name[i])) {
+        next_to_upper = true;
+        continue;
+      }
+      if (next_to_upper) {
+        result += to_upper(name[i]);
+        next_to_upper = false;
+      } else {
+        result += name[i];
+      }
+    }
+    return result;
+  }
+
+  std::string gen_native_field_name(std::string name) const {
+    for (std::size_t i = 0; i < name.size(); i++) {
+      if (!is_alnum(name[i])) {
+        name[i] = '_';
+      }
+    }
+    assert(name.size() > 0);
+    assert(name[name.size() - 1] != '_');
+    return name + "_";
+  }
+
+  std::string gen_native_class_name(std::string name) const {
+    if (name == "Object") {
+      assert(false);
+    }
+    if (name == "#") {
+      return "int";
+    }
+    for (std::size_t i = 0; i < name.size(); i++) {
+      if (!is_alnum(name[i])) {
+        name[i] = '_';
+      }
+    }
+    return name;
+  }
+
+  std::string gen_class_name(std::string name) const override {
+    if (name == "Object" || name == "#") {
+      assert(false);
+    }
+    return to_CamelCase(name);
+  }
+  std::string gen_field_name(std::string name) const override {
+    return gen_native_field_name(name);
+  }
+
+  std::string gen_native_type_name(const tl::tl_tree_type *tree_type, bool storage) const {
+    const tl::tl_type *t = tree_type->type;
+    const std::string &name = t->name;
+
+    if (name == "#") {
+      assert(false);
+    }
+    if (name == "Bool") {
+      return "bool";
+    }
+    if (name == "Int32") {
+      return "std::int32_t";
+    }
+    if (name == "Int53" || name == "Int64") {
+      return "std::int64_t";
+    }
+    if (name == "Double") {
+      return "double";
+    }
+    if (name == "String") {
+      return "std::string";
+    }
+    if (name == "Bytes") {
+      return "std::string";
+    }
+
+    if (name == "Vector") {
+      assert(t->arity == 1);
+      assert(tree_type->children.size() == 1);
+      assert(tree_type->children[0]->get_type() == tl::NODE_TYPE_TYPE);
+      const tl::tl_tree_type *child = static_cast<const tl::tl_tree_type *>(tree_type->children[0]);
+
+      return "std::vector<" + gen_native_type_name(child, storage) + ">";
+    }
+
+    assert(!is_built_in_simple_type(name) && !is_built_in_complex_type(name));
+
+    for (std::size_t i = 0; i < tree_type->children.size(); i++) {
+      assert(tree_type->children[i]->get_type() == tl::NODE_TYPE_NAT_CONST);
+    }
+
+    std::string native_class_name = gen_native_class_name(t->name);
+    if (t->constructors_num == 1) {
+      native_class_name = gen_native_class_name(t->constructors[0]->name);
+    }
+    return storage ? "td::td_api::object_ptr<td::td_api::" + native_class_name + ">"
+                   : "td::td_api::" + native_class_name + "";
+  }
+
+  std::string gen_type_name(const tl::tl_tree_type *tree_type, bool force) const {
+    const tl::tl_type *t = tree_type->type;
+    const std::string &name = t->name;
+
+    if (name == "#") {
+      assert(false);
+    }
+    if (name == "Bool") {
+      return force ? "Int" : "int ";
+    }
+    if (name == "Int32") {
+      return force ? "Int" : "int ";
+    }
+    if (name == "Int53" || name == "Int64") {
+      return force ? "Long" : "long long ";
+    }
+    if (name == "Double") {
+      return force ? "Double" : "double ";
+    }
+    if (name == "String") {
+      return force ? "String" : "char *";
+    }
+    if (name == "Bytes") {
+      return force ? "Bytes" : "struct TdBytes ";
+    }
+
+    if (name == "Vector") {
+      assert(t->arity == 1);
+      assert(tree_type->children.size() == 1);
+      assert(tree_type->children[0]->get_type() == tl::NODE_TYPE_TYPE);
+      const tl::tl_tree_type *child = static_cast<const tl::tl_tree_type *>(tree_type->children[0]);
+
+      return !force ? ("struct TdVector" + gen_type_name(child, true) + " *") : ("Vector" + gen_type_name(child, true));
+    }
+
+    assert(!is_built_in_simple_type(name) && !is_built_in_complex_type(name));
+
+    for (std::size_t i = 0; i < tree_type->children.size(); i++) {
+      assert(tree_type->children[i]->get_type() == tl::NODE_TYPE_NAT_CONST);
+    }
+
+    return !force ? ("struct Td" + gen_main_class_name(t) + " *") : gen_main_class_name(t);
+  }
+  std::string gen_type_name(const tl::tl_tree_type *tree_type) const override {
+    return gen_type_name(tree_type, false);
+  }
+  std::string gen_output_begin() const override {
+    if (is_header_ == 1) {
+      return "#pragma once\n"
+             "#ifdef __cplusplus\n"
+             "extern \"C\" {\n"
+             "#endif\n"
+             "#define TDC_VECTOR(tdc_type_name,tdc_type) \\\n"
+             "   struct TdVector ## tdc_type_name { \\\n"
+             "     int len;\\\n"
+             "     tdc_type *data;\\\n"
+             "   };\\\n"
+             "\n"
+             "TDC_VECTOR(Int,int)\n"
+             "TDC_VECTOR(Long,long long)\n"
+             "TDC_VECTOR(String,char *)\n"
+             "struct TdStackStorerMethods {\n"
+             "  void (*pack_string)(const char *s);\n"
+             "  void (*pack_bytes)(const unsigned char *s, int len);\n"
+             "  void (*pack_long)(long long x);\n"
+             "  void (*pack_double)(double x);\n"
+             "  void (*pack_bool)(int x);\n"
+             "  void (*new_table)(void);\n"
+             "  void (*new_array)(void);\n"
+             "  void (*new_field)(const char *name);\n"
+             "  void (*new_arr_field)(int idx);\n"
+             "};\n"
+             "struct TdStackFetcherMethods {\n"
+             "  char *(*get_string)(void);\n"
+             "  unsigned char *(*get_bytes)(int *len);\n"
+             "  long long (*get_long)(void);\n"
+             "  double (*get_double)(void);\n"
+             "  void (*pop)(void);\n"
+             "  void (*get_field)(const char *name);\n"
+             "  void (*get_arr_field)(int idx);\n"
+             "  int (*get_arr_size)(void);\n"
+             "  int (*is_nil)(void);\n"
+             "};\n"
+             "struct TdBytes {\n"
+             "  unsigned char *data;\n"
+             "  int len;\n"
+             "};\n";
+    }
+    if (is_header_ == -1) {
+      return "#pragma once\n"
+             "#include \"td/telegram/td_tdc_api.h\"\n"
+             "#include \"td/telegram/td_api.h\"\n";
+    }
+    return "#include \"td/telegram/td_tdc_api_inner.h\"\n\n"
+           "#include \"td/utils/format.h\"\n"
+           "#include \"td/utils/logging.h\"\n"
+           "#include \"td/utils/misc.h\"\n"
+           "#include \"td/utils/Slice.h\"\n"
+           "#include \"td/utils/tl_storers.h\"\n"
+           "\n";
+  }
+  std::string gen_output_end() const override {
+    if (is_header_ == 1) {
+      return "#ifdef __cplusplus\n"
+             "}\n"
+             "#endif\n";
+    } else if (is_header_ == -1) {
+      return "";
+    }
+    return "";
+  }
+
+  std::string gen_forward_class_declaration(const std::string &class_name, bool is_proxy) const override {
+    if (is_header_ != 1 || class_name == "") {
+      return "";
+    }
+    return "struct Td" + class_name +
+           ";\n"
+           "TDC_VECTOR(" +
+           class_name + ", struct Td" + class_name +
+           " *);\n"
+           "TDC_VECTOR(Vector" +
+           class_name + ", struct TdVector" + class_name + " *);\n";
+  }
+
+  std::string gen_class_begin(const std::string &class_name, const std::string &base_class_name,
+                              bool is_proxy) const override {
+    if (is_header_ != 1 || class_name == "") {
+      return "";
+    }
+
+    std::string tail = "";
+    if (class_name == "Function" || class_name == "Object") {
+      tail = "};\n";
+    }
+    return "struct Td" + class_name + " {\n" + "  int ID;\n  int refcnt;\n" + tail;
+  }
+  std::string gen_class_end() const override {
+    return "";
+  }
+
+  std::string gen_field_definition(const std::string &class_name, const std::string &type_name,
+                                   const std::string &field_name) const override {
+    if (is_header_ != 1 || class_name == "") {
+      return "";
+    }
+    return "  " + type_name + field_name + ";\n";
+  }
+
+  std::string gen_store_function_begin(const std::string &storer_name, const std::string &class_name, int arity,
+                                       std::vector<tl::var_description> &vars, int storer_type) const override {
+    return "";
+  }
+  std::string gen_store_function_end(const std::vector<tl::var_description> &vars, int storer_type) const override {
+    return "";
+  }
+
+  std::string gen_constructor_begin(int fields_num, const std::string &class_name, bool is_default) const override {
+    if (!is_default || is_header_ == -1 || class_name == "") {
+      return "";
+    }
+    std::stringstream ss;
+    if (is_header_ == 1) {
+      ss << "};\n";
+    }
+    ss << "struct Td" + gen_class_name(class_name) + " *TdCreateObject" + gen_class_name(class_name) + " (" +
+              (fields_num ? "" : "void");
+    return ss.str();
+  }
+  std::string gen_constructor_parameter(int field_num, const std::string &class_name, const tl::arg &a,
+                                        bool is_default) const override {
+    if (!is_default || is_header_ == -1) {
+      return "";
+    }
+    std::stringstream ss;
+    auto field_type = gen_field_type(a);
+    ss << (field_num == 0 ? "" : ", ");
+    ss << field_type << gen_field_name(a.name);
+    return ss.str();
+  }
+  std::string gen_constructor_field_init(int field_num, const std::string &class_name, const tl::arg &a,
+                                         bool is_default) const override {
+    return "";
+  }
+  std::string gen_constructor_end(const tl::tl_combinator *t, int fields_num, bool is_default) const override {
+    if (!is_default || is_header_ == -1) {
+      return "";
+    }
+    if (is_header_ == 1) {
+      return ");\n";
+    }
+    std::stringstream ss;
+    ss << ") {\n";
+    auto type_name = "struct Td" + gen_class_name(t->name);
+    ss << "  auto var = new " << type_name << " ();\n";
+    ss << "  var->ID = CODE_" << gen_class_name(t->name) << ";\n";
+    ss << "  var->refcnt = 1;\n";
+    for (auto &it : t->args) {
+      const tl::tl_tree_type *T = static_cast<const tl::tl_tree_type *>(it.type);
+      auto field_name = gen_field_name(it.name);
+      if (T->type->name == "String") {
+        ss << "  var->" << field_name << " = (" << field_name << ") ? td::str_dup (td::Slice (" << field_name
+           << ")) : nullptr;\n";
+      } else {
+        ss << "  var->" << field_name << " = " << field_name << ";\n";
+      }
+    }
+    ss << "  return var;\n}\n";
+    return ss.str();
+  }
+  std::string gen_additional_function(const std::string &function_name, const tl::tl_combinator *t,
+                                      bool is_function) const override {
+    std::stringstream ss;
+    if (function_name == "enum") {
+      return ss.str();
+    }
+    if (function_name == "TdDestroyObject") {
+      auto class_name = gen_class_name(t->name);
+      if (is_header_ == 1) {
+        ss << "void TdDestroyObject" + class_name + " (struct Td" + class_name + " *var);\n";
+        return ss.str();
+      }
+      if (is_header_ == -1) {
+        ss << "void TdDestroyObject (struct Td" + class_name + " *var);\n";
+        return ss.str();
+      }
+      ss << "void TdDestroyObject" + class_name + " (struct Td" + class_name + " *var) {\n";
+      ss << "  TdDestroyObject (var);\n";
+      ss << "}\n";
+      ss << "void TdDestroyObject (struct Td" + class_name + " *var)";
+
+      file_store_methods_destroy M(this);
+      gen_object_store(ss, t, M);
+      return ss.str();
+    }
+    if (function_name == "TdSerialize" && is_header_ != -1) {
+      auto class_name = gen_class_name(t->name);
+      ss << "char *TdSerialize" + class_name + " (struct Td" + class_name + " *var)";
+      if (is_header_ == 1) {
+        ss << ";\n";
+        return ss.str();
+      }
+      ss << " {\n";
+      ss << "  return td::str_dup (TdToString (var));\n";
+      ss << "}\n";
+      return ss.str();
+    }
+    if (function_name == "TdToString" && is_header_ != 1) {
+      auto class_name = gen_class_name(t->name);
+      ss << "std::string TdToString (struct Td" + class_name + " *var)";
+      if (is_header_ == -1) {
+        ss << ";\n";
+        return ss.str();
+      }
+      ss << " {\n";
+      ss << "  return to_string (TdConvertToInternal (var));\n";
+      ss << "}\n";
+      return ss.str();
+    }
+    if (function_name == "TdConvertToInternal" && is_header_ != 1) {
+      auto class_name = gen_class_name(t->name);
+      auto native_class_name = gen_native_class_name(t->name);
+      ss << "td::td_api::object_ptr<td::td_api::" << native_class_name
+         << "> TdConvertToInternal (struct Td" + class_name + " *var)";
+      if (is_header_ == -1) {
+        ss << ";\n";
+        return ss.str();
+      }
+      file_store_methods_to_td M(this);
+      gen_object_store(ss, t, M);
+      return ss.str();
+    }
+    if (function_name == "TdConvertFromInternal" && is_header_ != 1) {
+      auto class_name = gen_class_name(t->name);
+      auto native_class_name = gen_native_class_name(t->name);
+      ss << "struct Td" << class_name << " *TdConvertFromInternal (const td::td_api::" << native_class_name
+         << " &from)";
+      if (is_header_ == -1) {
+        ss << ";\n";
+        return ss.str();
+      }
+      file_fetch_methods_from_td M(this);
+      gen_object_fetch(ss, t, M);
+      return ss.str();
+    }
+    if (function_name == "TdStackStorer") {
+      auto class_name = gen_class_name(t->name);
+      if (is_header_ == 1) {
+        ss << "void TdStackStorer" + class_name + " (struct Td" + class_name +
+                  " *var, struct TdStackStorerMethods *M);\n";
+        return ss.str();
+      }
+      if (is_header_ == -1) {
+        ss << "void TdStackStorer (struct Td" + class_name + " *var, struct TdStackStorerMethods *M);\n";
+        return ss.str();
+      }
+      ss << "void TdStackStorer" + class_name + " (struct Td" + class_name +
+                " *var, struct TdStackStorerMethods *M) {\n";
+      ss << "  TdStackStorer (var, M);\n";
+      ss << "}\n";
+      ss << "void TdStackStorer (struct Td" + class_name + " *var, struct TdStackStorerMethods *M)";
+
+      file_store_methods_stack M(this);
+      gen_object_store(ss, t, M);
+      return ss.str();
+    }
+    if (function_name == "TdStackFetcher" && is_header_ != -1) {
+      auto class_name = gen_class_name(t->name);
+      ss << "struct Td" << class_name << " *TdStackFetcher" + class_name + " (struct TdStackFetcherMethods *M)";
+      if (is_header_ == 1) {
+        ss << ";\n";
+        return ss.str();
+      }
+
+      file_fetch_methods_stack M(this);
+      gen_object_fetch(ss, t, M);
+      return ss.str();
+    }
+    return ss.str();
+  }
+
+  struct file_store_methods {
+    file_store_methods() = default;
+    file_store_methods(const file_store_methods &) = delete;
+    file_store_methods &operator=(const file_store_methods &) = delete;
+    virtual ~file_store_methods() = default;
+    virtual void store_simple_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                                   std::string type_name) const {
+      assert(false);
+    }
+    virtual void store_common_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                                   std::string type_name) const {
+      assert(false);
+    }
+    virtual void store_array_start(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                                   const tl::tl_tree_type *tree_type) const {
+      assert(false);
+    }
+    virtual void store_array_el(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                                std::string idx) const {
+      assert(false);
+    }
+    virtual void store_array_finish(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                                    const tl::tl_tree_type *tree_type) const {
+      assert(false);
+    }
+    virtual void store_nil(std::stringstream &ss, std::string offset) const {
+      assert(false);
+    }
+    virtual std::string store_field_start(std::stringstream &ss, std::string offset, int depth,
+                                          const tl::tl_tree_type *tree_type) const {
+      assert(false);
+      return "";
+    }
+    virtual void store_field_finish(std::stringstream &ss, std::string offset, std::string res_var) const {
+      assert(false);
+    }
+    virtual void store_arg_finish(std::stringstream &ss, std::string offset, std::string arg_name,
+                                  std::string res_var) const {
+      assert(false);
+    }
+    virtual void store_constructor_start(std::stringstream &ss, std::string offset, const tl::tl_combinator *t) const {
+    }
+    virtual void store_constructor_finish(std::stringstream &ss, std::string offset, const tl::tl_combinator *t,
+                                          std::vector<std::string> res_var) const {
+      assert(false);
+    }
+  };
+
+  struct file_store_methods_to_td : public file_store_methods {
+    explicit file_store_methods_to_td(const class TlWriterCCommon *cl) : cl(cl) {
+    }
+    void store_simple_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                           std::string type_name) const override {
+      if (type_name == "String") {
+        ss << offset << res_var << " = (" << var << ") ? " << var << ": \"\";\n";
+      } else if (type_name == "Bytes") {
+        ss << offset << res_var << " = std::string ((char *)" << var << ".data, " << var << ".len);\n";
+      } else if (type_name == "Bool") {
+        ss << offset << res_var << " = " << var << " != 0;\n";
+      } else {
+        ss << offset << res_var << " = " << var << ";\n";
+      }
+    }
+    void store_common_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                           std::string type_name) const override {
+      ss << offset << res_var << " = TdConvertToInternal (" << var << ");\n";
+    }
+    void store_array_start(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                           const tl::tl_tree_type *tree_type) const override {
+    }
+    void store_array_el(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                        std::string idx) const override {
+      ss << offset << res_var << ".push_back (std::move (" << var << "));\n";
+    }
+    void store_array_finish(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                            const tl::tl_tree_type *tree_type) const override {
+    }
+    void store_nil(std::stringstream &ss, std::string offset) const override {
+      ss << offset << "return nullptr;\n";
+    }
+    std::string store_field_start(std::stringstream &ss, std::string offset, int depth,
+                                  const tl::tl_tree_type *tree_type) const override {
+      std::string res_var = "v" + int_to_string(depth);
+      ss << offset << cl->gen_native_type_name(tree_type, true) << " " << res_var << ";\n";
+      return res_var;
+    }
+    void store_field_finish(std::stringstream &ss, std::string offset, std::string res_var) const override {
+    }
+    void store_arg_finish(std::stringstream &ss, std::string offset, std::string arg_name,
+                          std::string res_var) const override {
+    }
+    void store_constructor_finish(std::stringstream &ss, std::string offset, const tl::tl_combinator *t,
+                                  std::vector<std::string> res_var) const override {
+      auto native_class_name = cl->gen_native_class_name(t->name);
+      ss << offset << "return td::td_api::make_object<td::td_api::" << native_class_name << ">(";
+      bool is_first = true;
+      for (auto &var_name : res_var) {
+        if (is_first) {
+          is_first = false;
+        } else {
+          ss << ", ";
+        }
+
+        ss << "std::move (" << var_name << ")";
+      }
+      ss << ");\n";
+    }
+    const class TlWriterCCommon *cl;
+  };
+
+  struct file_store_methods_destroy : public file_store_methods {
+    explicit file_store_methods_destroy(const class TlWriterCCommon *cl) : cl(cl) {
+    }
+    void store_simple_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                           std::string type_name) const override {
+      if (type_name == "String") {
+        ss << offset << "free (" << var << ");\n";
+      } else if (type_name == "Bytes") {
+        ss << offset << "delete[]" << var << ".data;\n";
+      }
+    }
+    void store_common_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                           std::string type_name) const override {
+      ss << offset << "TdDestroyObject (" << var << ");\n";
+    }
+    void store_array_start(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                           const tl::tl_tree_type *tree_type) const override {
+    }
+    void store_array_el(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                        std::string idx) const override {
+    }
+    void store_array_finish(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                            const tl::tl_tree_type *tree_type) const override {
+      ss << offset << "delete[] " << var << "->data;\n" << offset << "delete " << var << ";\n";
+    }
+    void store_nil(std::stringstream &ss, std::string offset) const override {
+      ss << offset << "return;\n";
+    }
+    std::string store_field_start(std::stringstream &ss, std::string offset, int depth,
+                                  const tl::tl_tree_type *tree_type) const override {
+      return "";
+    }
+    void store_field_finish(std::stringstream &ss, std::string offset, std::string res_var) const override {
+    }
+    void store_arg_finish(std::stringstream &ss, std::string offset, std::string arg_name,
+                          std::string res_var) const override {
+    }
+    void store_constructor_start(std::stringstream &ss, std::string offset, const tl::tl_combinator *t) const override {
+      ss << "#if TD_MSVC\n";
+      ss << offset << "static_assert (sizeof (long) == sizeof (var->refcnt), \"Illegal InterlockedDecrement\");\n";
+      ss << offset << "int ref = InterlockedDecrement (reinterpret_cast<long *>(&var->refcnt));\n";
+      ss << "#else\n";
+      ss << offset << "int ref = __sync_add_and_fetch (&var->refcnt, -1);\n";
+      ss << "#endif\n";
+      ss << offset << "if (ref < 0) {\n";
+      ss << offset << "  LOG(FATAL) << \"Negative reference counter in Td C object struct\";\n";
+      ss << offset << "}\n";
+      ss << offset << "if (ref > 0) {\n";
+      ss << offset << "  return;\n";
+      ss << offset << "}\n";
+    }
+    void store_constructor_finish(std::stringstream &ss, std::string offset, const tl::tl_combinator *t,
+                                  std::vector<std::string> res_var) const override {
+      ss << offset << "delete var;\n";
+    }
+    const class TlWriterCCommon *cl;
+  };
+  struct file_store_methods_stack : public file_store_methods {
+    explicit file_store_methods_stack(const class TlWriterCCommon *cl) : cl(cl) {
+    }
+    void store_simple_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                           std::string type_name) const override {
+      if (type_name == "String") {
+        ss << offset << "M->pack_string (" << var << ");\n";
+      } else if (type_name == "Bytes") {
+        ss << offset << "M->pack_bytes (" << var << ".data, " << var << ".len);\n";
+      } else if (type_name == "Int32" || type_name == "Int53" || type_name == "Int64") {
+        ss << offset << "M->pack_long (" << var << ");\n";
+      } else if (type_name == "Bool") {
+        ss << offset << "M->pack_bool (" << var << ");\n";
+      } else if (type_name == "Double") {
+        ss << offset << "M->pack_double (" << var << ");\n";
+      } else {
+        ss << "????" << type_name << "\n";
+      }
+    }
+    void store_common_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                           std::string type_name) const override {
+      ss << offset << "TdStackStorer (" << var << ", M);\n";
+    }
+    void store_array_start(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                           const tl::tl_tree_type *tree_type) const override {
+      ss << offset << "M->new_array ();\n";
+    }
+    void store_array_el(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                        std::string idx) const override {
+      ss << offset << "M->new_arr_field (" << idx << ");\n";
+    }
+    void store_array_finish(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                            const tl::tl_tree_type *tree_type) const override {
+    }
+    void store_nil(std::stringstream &ss, std::string offset) const override {
+      ss << offset << "M->pack_bool (0);\n" << offset << "return;\n";
+    }
+    std::string store_field_start(std::stringstream &ss, std::string offset, int depth,
+                                  const tl::tl_tree_type *tree_type) const override {
+      return "";
+    }
+    void store_field_finish(std::stringstream &ss, std::string offset, std::string res_var) const override {
+    }
+    void store_arg_finish(std::stringstream &ss, std::string offset, std::string arg_name,
+                          std::string res_var) const override {
+      ss << offset << "M->new_field (\"" << arg_name << "\");\n";
+    }
+    void store_constructor_start(std::stringstream &ss, std::string offset, const tl::tl_combinator *t) const override {
+      ss << offset << "M->new_table ();\n";
+      auto class_name = cl->gen_class_name(t->name);
+      ss << offset << "M->pack_string (\"" << class_name << "\");\n";
+      ss << offset << "M->new_field (\"ID\");\n";
+    }
+    void store_constructor_finish(std::stringstream &ss, std::string offset, const tl::tl_combinator *t,
+                                  std::vector<std::string> res_var) const override {
+    }
+    const class TlWriterCCommon *cl;
+  };
+
+  struct file_fetch_methods {
+    file_fetch_methods() = default;
+    file_fetch_methods(const file_fetch_methods &) = delete;
+    file_fetch_methods &operator=(const file_fetch_methods &) = delete;
+
+    virtual ~file_fetch_methods() = default;
+
+    virtual std::string fetch_field_start(std::stringstream &ss, std::string offset, int depth,
+                                          const tl::tl_tree_type *tree_type) const {
+      assert(false);
+      return "";
+    }
+    virtual void fetch_simple_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                                   std::string type_name) const {
+      assert(false);
+    }
+    virtual void fetch_common_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                                   const tl::tl_tree_type *tree_type) const {
+      assert(false);
+    }
+    virtual void fetch_array_size(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                                  const tl::tl_tree_type *tree_type) const {
+      assert(false);
+    }
+    virtual std::string fetch_array_field_start(std::stringstream &ss, std::string offset, std::string res_var,
+                                                std::string var, std::string idx,
+                                                const tl::tl_tree_type *tree_type) const {
+      assert(false);
+      return "";
+    }
+    virtual std::string fetch_dict_field_start(std::stringstream &ss, std::string offset, std::string res_var,
+                                               std::string var, std::string key,
+                                               const tl::tl_tree_type *tree_type) const {
+      assert(false);
+      return "";
+    }
+    virtual void fetch_field_finish(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                                    const tl::tl_tree_type *tree_type) const {
+      assert(false);
+    }
+  };
+
+  struct file_fetch_methods_from_td : public file_fetch_methods {
+    explicit file_fetch_methods_from_td(const class TlWriterCCommon *cl) : cl(cl) {
+    }
+    std::string fetch_field_start(std::stringstream &ss, std::string offset, int depth,
+                                  const tl::tl_tree_type *tree_type) const override {
+      return "";
+    }
+    void fetch_simple_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                           std::string type_name) const override {
+      if (type_name == "String") {
+        ss << offset << res_var << " = (" << var << ".length ()) ? td::str_dup (" << var << ") : nullptr;\n";
+      } else if (type_name == "Bytes") {
+        ss << offset << res_var << ".len = (int)" << var << ".length ();\n";
+        ss << offset << "if (" << res_var << ".len) {\n";
+        ss << offset << "  " << res_var << ".data = new unsigned char[" << res_var << ".len];\n";
+        ss << offset << "  memcpy (" << res_var << ".data, " << var << ".c_str (), " << res_var << ".len);\n";
+        ss << offset << "} else {\n";
+        ss << offset << "  " << res_var << ".data = nullptr;\n";
+        ss << offset << "}\n";
+      } else {
+        ss << offset << res_var << " = " << var << ";\n";
+      }
+    }
+    void fetch_common_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                           const tl::tl_tree_type *tree_type) const override {
+      auto native_type_name = cl->gen_native_type_name(tree_type, false);
+      ss << offset << "if (!" << var << ") {\n"
+         << offset << "  " << res_var << " = nullptr;\n"
+         << offset << "} else {\n"
+         << offset << "  " << res_var << " = TdConvertFromInternal (static_cast<const " << native_type_name << " &>(*"
+         << var << "));\n"
+         << offset << "}\n";
+    }
+    void fetch_array_size(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                          const tl::tl_tree_type *tree_type) const override {
+      ss << offset << res_var << " = (int)" << var << ".size ();\n";
+    }
+    std::string fetch_array_field_start(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                                        std::string idx, const tl::tl_tree_type *tree_type) const override {
+      return var + "[" + idx + "]";
+    }
+    std::string fetch_dict_field_start(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                                       std::string key, const tl::tl_tree_type *tree_type) const override {
+      return var + "." + key;
+    }
+    void fetch_field_finish(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                            const tl::tl_tree_type *tree_type) const override {
+    }
+    const class TlWriterCCommon *cl;
+  };
+
+  struct file_fetch_methods_stack : public file_fetch_methods {
+    explicit file_fetch_methods_stack(const class TlWriterCCommon *cl) : cl(cl) {
+    }
+    std::string fetch_field_start(std::stringstream &ss, std::string offset, int depth,
+                                  const tl::tl_tree_type *tree_type) const override {
+      return "";
+    }
+    void fetch_simple_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                           std::string type_name) const override {
+      if (type_name == "String") {
+        ss << offset << res_var << " = M->get_string ();\n";
+      } else if (type_name == "Bytes") {
+        ss << offset << res_var << ".data = M->get_bytes (&" << res_var << ".len);\n";
+      } else if (type_name == "Int32" || type_name == "Bool") {
+        ss << offset << res_var << " = (int)M->get_long ();\n";
+      } else if (type_name == "Int53" || type_name == "Int64") {
+        ss << offset << res_var << " = M->get_long ();\n";
+      } else if (type_name == "Double") {
+        ss << offset << res_var << " = M->get_double ();\n";
+      } else {
+        ss << "??????" << type_name << "\n";
+      }
+    }
+    void fetch_common_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                           const tl::tl_tree_type *tree_type) const override {
+      auto class_name = cl->gen_main_class_name(tree_type->type);
+      ss << offset << "if (M->is_nil ()) {\n"
+         << offset << "  " << res_var << " = nullptr;\n"
+         << offset << "} else {\n"
+         << offset << "  " << res_var << " = TdStackFetcher" << class_name << " (M);\n"
+         << offset << "}\n";
+    }
+    void fetch_array_size(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                          const tl::tl_tree_type *tree_type) const override {
+      ss << offset << res_var << " = M->get_arr_size ();\n";
+    }
+    std::string fetch_array_field_start(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                                        std::string idx, const tl::tl_tree_type *tree_type) const override {
+      ss << offset << "  M->get_arr_field (" << idx << ");\n";
+      return "";
+    }
+    std::string fetch_dict_field_start(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                                       std::string key, const tl::tl_tree_type *tree_type) const override {
+      ss << offset << "M->get_field (\"" << key << "\");\n";
+      return "";
+    }
+    void fetch_field_finish(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
+                            const tl::tl_tree_type *tree_type) const override {
+      ss << offset << "M->pop ();\n";
+    }
+    const class TlWriterCCommon *cl;
+  };
+
+  std::string gen_field_store(std::stringstream &ss, std::string offset, std::string var, int depth,
+                              const tl::tl_tree_type *tree_type, const file_store_methods &M) const {
+    std::string res_var = M.store_field_start(ss, offset, depth, tree_type);
+    if (is_built_in_simple_type(tree_type->type->name)) {
+      M.store_simple_type(ss, offset, res_var, var, tree_type->type->name);
+    } else if (!is_built_in_complex_type(tree_type->type->name)) {
+      M.store_common_type(ss, offset, res_var, var, tree_type->type->name);
+    } else {
+      const tl::tl_tree_type *child = static_cast<const tl::tl_tree_type *>(tree_type->children[0]);
+
+      std::string it = "i" + int_to_string(depth);
+
+      M.store_array_start(ss, offset, res_var, var, tree_type);
+      ss << offset << "for (int " << it << " = 0; " << it << " < " << var << "->len; " << it << "++) {\n";
+      auto f_res_var = gen_field_store(ss, offset + "  ", var + "->data[" + it + "]", depth + 1, child, M);
+      M.store_array_el(ss, offset + "  ", res_var, f_res_var, it);
+      ss << offset << "}\n";
+      M.store_array_finish(ss, offset, res_var, var, tree_type);
+    }
+    M.store_field_finish(ss, offset, res_var);
+    return res_var;
+  }
+  void gen_object_store(std::stringstream &ss, const tl::tl_combinator *t, const file_store_methods &M) const {
+    ss << " {\n"
+       << "  if (!var) {\n";
+    M.store_nil(ss, "    ");
+    ss << "  }\n";
+    M.store_constructor_start(ss, "  ", t);
+
+    std::vector<std::string> flds;
+    int d = 0;
+    for (auto &it : t->args) {
+      const tl::tl_tree_type *tree_type = static_cast<const tl::tl_tree_type *>(it.type);
+      flds.push_back(gen_field_store(ss, "  ", "var->" + gen_field_name(it.name), 100 * d, tree_type, M));
+      d++;
+      M.store_arg_finish(ss, "  ", gen_field_name(it.name), flds[d - 1]);
+    }
+    M.store_constructor_finish(ss, "  ", t, flds);
+    ss << "}\n";
+  }
+  void gen_field_fetch(std::stringstream &ss, std::string offset, std::string res_var, std::string var, int depth,
+                       const tl::tl_tree_type *tree_type, const file_fetch_methods &M) const {
+    if (is_built_in_simple_type(tree_type->type->name)) {
+      M.fetch_simple_type(ss, offset, res_var, var, tree_type->type->name);
+    } else if (!is_built_in_complex_type(tree_type->type->name)) {
+      M.fetch_common_type(ss, offset, res_var, var, tree_type);
+    } else {
+      const tl::tl_tree_type *child = static_cast<const tl::tl_tree_type *>(tree_type->children[0]);
+
+      ss << offset << res_var << " = new Td" << gen_type_name(tree_type, true) << " ();\n";
+      M.fetch_array_size(ss, offset, res_var + "->len", var, tree_type);
+      ss << offset << res_var << "->data = new " << gen_type_name(child) << " [" << res_var << "->len];\n";
+
+      std::string it = "i" + int_to_string(depth);
+      ss << offset << "for (int " << it << " = 0; " << it << " < " << res_var << "->len; " << it << "++) {\n";
+      auto new_var = M.fetch_array_field_start(ss, offset, res_var, var, it, child);
+      gen_field_fetch(ss, offset + "  ", res_var + "->data[" + it + "]", new_var, depth + 1, child, M);
+      ss << offset << "}\n";
+    }
+    M.fetch_field_finish(ss, offset, res_var, var, tree_type);
+  }
+  void gen_object_fetch(std::stringstream &ss, const tl::tl_combinator *t, const file_fetch_methods &M) const {
+    auto type_name = gen_class_name(t->name);
+    ss << " {\n"
+       << "  auto res = new Td" << type_name << " ();\n"
+       << "  res->ID = CODE_" << type_name << ";\n"
+       << "  res->refcnt = 1;\n";
+    int d = 0;
+    for (auto &it : t->args) {
+      const tl::tl_tree_type *tree_type = static_cast<const tl::tl_tree_type *>(it.type);
+      auto new_var = M.fetch_dict_field_start(ss, "  ", "res", "from", gen_field_name(it.name), tree_type);
+      gen_field_fetch(ss, "  ", "res->" + gen_field_name(it.name), new_var, 100 * d, tree_type, M);
+      d++;
+    }
+    ss << "  return res;\n"
+       << "}\n";
+  }
+
+  std::string gen_array_type_name(const tl::tl_tree_array *arr, const std::string &field_name) const override {
+    assert(false);
+    return std::string();
+  }
+  std::string gen_var_type_name() const override {
+    assert(false);
+    return std::string();
+  }
+
+  std::string gen_int_const(const tl::tl_tree *tree_c, const std::vector<tl::var_description> &vars) const override {
+    assert(false);
+    return std::string();
+  }
+
+  std::string gen_var_name(const tl::var_description &desc) const override {
+    assert(false);
+    return "";
+  }
+  std::string gen_parameter_name(int index) const override {
+    assert(false);
+    return "";
+  }
+
+  std::string gen_class_alias(const std::string &class_name, const std::string &alias_name) const override {
+    return "";
+  }
+
+  std::string gen_vars(const tl::tl_combinator *t, const tl::tl_tree_type *result_type,
+                       std::vector<tl::var_description> &vars) const override {
+    assert(vars.empty());
+    return "";
+  }
+  std::string gen_function_vars(const tl::tl_combinator *t, std::vector<tl::var_description> &vars) const override {
+    assert(vars.empty());
+    return "";
+  }
+  std::string gen_uni(const tl::tl_tree_type *result_type, std::vector<tl::var_description> &vars,
+                      bool check_negative) const override {
+    assert(result_type->children.empty());
+    return "";
+  }
+  std::string gen_constructor_id_store(std::int32_t id, int storer_type) const override {
+    return "";
+  }
+  std::string gen_field_fetch(int field_num, const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                              int parser_type) const override {
+    return "";
+  }
+  std::string gen_field_store(const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                              int storer_type) const override {
+    return "";
+  }
+  std::string gen_type_fetch(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                             const std::vector<tl::var_description> &vars, int parser_type) const override {
+    assert(vars.empty());
+    return "";
+  }
+
+  std::string gen_type_store(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                             const std::vector<tl::var_description> &vars, int storer_type) const override {
+    return "";
+  }
+  std::string gen_var_type_fetch(const tl::arg &a) const override {
+    assert(false);
+    return "";
+  }
+
+  std::string gen_get_id(const std::string &class_name, std::int32_t id, bool is_proxy) const override {
+    if (is_proxy || is_header_ != 1) {
+      return "";
+    }
+    // return "#define CODE_" + class_name + " " + int_to_string(id) + "\n";
+    return "";
+  }
+
+  std::string gen_function_result_type(const tl::tl_tree *result) const override {
+    return "";
+  }
+
+  std::string gen_fetch_function_begin(const std::string &parser_name, const std::string &class_name, int arity,
+                                       std::vector<tl::var_description> &vars, int parser_type) const override {
+    return "";
+  }
+  std::string gen_fetch_function_end(int field_num, const std::vector<tl::var_description> &vars,
+                                     int parser_type) const override {
+    return "";
+  }
+
+  std::string gen_fetch_function_result_begin(const std::string &parser_name, const std::string &class_name,
+                                              const tl::tl_tree *result) const override {
+    return "";
+  }
+  std::string gen_fetch_function_result_end() const override {
+    return "";
+  }
+  std::string gen_fetch_function_result_any_begin(const std::string &parser_name, const std::string &class_name,
+                                                  bool is_proxy) const override {
+    return "";
+  }
+  std::string gen_fetch_function_result_any_end(bool is_proxy) const override {
+    return "";
+  }
+
+  std::string gen_fetch_switch_begin() const override {
+    return "";
+  }
+  std::string gen_fetch_switch_case(const tl::tl_combinator *t, int arity) const override {
+    return "";
+  }
+  std::string gen_fetch_switch_end() const override {
+    return "";
+  }
+
+  std::string gen_additional_proxy_function_begin(const std::string &function_name, const tl::tl_type *type,
+                                                  const std::string &name, int arity, bool is_function) const override {
+    std::stringstream ss;
+    std::string class_name;
+    std::string native_class_name;
+
+    if (type != nullptr) {
+      class_name = gen_main_class_name(type);
+      native_class_name = gen_native_class_name(type->name);
+    } else {
+      if (is_function) {
+        class_name = "Function";
+        native_class_name = "Function";
+      } else {
+        class_name = "Object";
+        native_class_name = "Object";
+      }
+    }
+    if (is_header_ == 1 && function_name == "TdConvertToInternal" && type != nullptr && !is_function) {
+      ss << "};\n";
+    }
+
+    if (function_name == "enum") {
+      if (is_header_ != 1) {
+        return ss.str();
+      }
+      ss << "enum List_" + class_name << " {\n";
+      return ss.str();
+    }
+
+    if (function_name == "TdDestroyObject") {
+      if (is_header_ == 1) {
+        ss << "void TdDestroyObject" + class_name + " (struct Td" + class_name + " *var);\n";
+        return ss.str();
+      }
+      if (is_header_ == -1) {
+        ss << "void TdDestroyObject (struct Td" + class_name + " *var);\n";
+        return ss.str();
+      }
+      ss << "void TdDestroyObject" + class_name + " (struct Td" + class_name + " *var) {\n";
+      ss << "  TdDestroyObject (var);\n";
+      ss << "}\n";
+      ss << "void TdDestroyObject (struct Td" + class_name + " *var)";
+    }
+    if (function_name == "TdSerialize" && is_header_ != -1) {
+      ss << "char *TdSerialize" + class_name + " (struct Td" + class_name + " *var)";
+      if (is_header_ == 1) {
+        ss << ";\n";
+        return ss.str();
+      }
+      ss << " {\n";
+      ss << "  return td::str_dup (TdToString (var));\n";
+      ss << "}\n";
+      return ss.str();
+    }
+    if (function_name == "TdToString" && is_header_ != 1) {
+      ss << "std::string TdToString (struct Td" + class_name + " *var)";
+      if (is_header_ == -1) {
+        ss << ";\n";
+        return ss.str();
+      }
+      ss << " {\n";
+      ss << "  return to_string (TdConvertToInternal (var));\n";
+      ss << "}\n";
+      return ss.str();
+    }
+    if (function_name == "TdConvertToInternal" && is_header_ != 1) {
+      ss << "td::td_api::object_ptr<td::td_api::" << native_class_name
+         << "> TdConvertToInternal (struct Td" + class_name + " *var)";
+      if (is_header_ == -1) {
+        ss << ";\n";
+        return ss.str();
+      }
+    }
+    if (function_name == "TdConvertFromInternal" && is_header_ != 1) {
+      ss << "struct Td" << class_name << " *TdConvertFromInternal (const td::td_api::" << native_class_name
+         << " &from)";
+      if (is_header_ == -1) {
+        ss << ";\n";
+        return ss.str();
+      }
+    }
+    if (function_name == "TdStackStorer") {
+      if (is_header_ == 1) {
+        ss << "void TdStackStorer" + class_name + " (struct Td" + class_name +
+                  " *var, struct TdStackStorerMethods *M);\n";
+        return ss.str();
+      }
+      if (is_header_ == -1) {
+        ss << "void TdStackStorer (struct Td" + class_name + " *var, struct TdStackStorerMethods *M);\n";
+        return ss.str();
+      }
+      ss << "void TdStackStorer" + class_name + " (struct Td" + class_name +
+                " *var, struct TdStackStorerMethods *M) {\n";
+      ss << "  TdStackStorer (var, M);\n";
+      ss << "}\n";
+      ss << "void TdStackStorer (struct Td" + class_name + " *var, struct TdStackStorerMethods *M)";
+    }
+    if (function_name == "TdStackFetcher" && is_header_ != -1) {
+      ss << "struct Td" << class_name << " *TdStackFetcher" + class_name + " (struct TdStackFetcherMethods *M)";
+      if (is_header_ == 1) {
+        ss << ";\n";
+        return ss.str();
+      }
+    }
+    if (is_header_ != 0) {
+      return ss.str();
+    }
+
+    if (function_name == "TdDestroyObject" || function_name == "TdConvertToInternal" ||
+        function_name == "TdStackStorer") {
+      ss << " {\n";
+      std::string prefix = "";
+      if (function_name == "TdConvertToInternal") {
+        prefix = "  if (!var) { return nullptr; }\n";
+      } else if (function_name == "TdDestroyObject") {
+        prefix = "  if (!var) { return; }\n";
+      }
+      if (function_name == "TdStackStorer") {
+        prefix = "  if (!var) { M->pack_bool (0); return; }\n";
+      }
+      ss << prefix
+         << "  int constructor = var->ID;\n"
+            "  switch (constructor) {\n";
+    } else if (function_name == "TdConvertFromInternal") {
+      ss << " {\n"
+            //"  if (!from) { return nullptr; }\n"
+            "  int constructor = from.get_id ();\n"
+            "  switch (constructor) {\n";
+    } else if (function_name == "TdStackFetcher") {
+      ss << " {\n"
+            "  M->get_field (\"ID\");\n"
+            "  char *constructor_old = M->get_string ();\n"
+            "  M->pop ();\n"
+            "  std::string constructor = constructor_old;\n"
+            "  free (constructor_old);\n"
+            "  ";
+    } else {
+      ss << "??????";
+    }
+
+    return ss.str();
+  }
+
+  std::string gen_additional_proxy_function_case(const std::string &function_name, const tl::tl_type *type,
+                                                 const std::string &class_name, int arity) const override {
+    if (is_header_ != (function_name == "enum" ? 1 : 0)) {
+      return "";
+    }
+
+    assert(type != nullptr);
+    if (function_name == "TdDestroyObject" || function_name == "TdConvertToInternal" ||
+        function_name == "TdStackStorer") {
+      std::string extra_arg = "";
+      if (function_name == "TdStackStorer") {
+        extra_arg = ", M";
+      }
+      return "    case CODE_" + class_name + ": return " + function_name + " ((struct Td" + class_name + " *)var" +
+             extra_arg + ");\n";
+    } else if (function_name == "TdConvertFromInternal") {
+      std::string native_class_name = class_name;
+      native_class_name[0] = to_lower(native_class_name[0]);
+      return "    case CODE_" + class_name + ": return (struct TdNullaryObject *)" + function_name +
+             "(static_cast<const td::td_api::" + native_class_name + " &>(from));\n";
+    } else if (function_name == "TdStackFetcher") {
+      return "if (constructor == \"" + class_name +
+             "\") {\n"
+             "    return (struct TdNullaryObject *)TdStackFetcher" +
+             class_name +
+             " (M);\n"
+             "  }\n  ";
+    } else if (function_name == "enum") {
+      // return "  CODE_" + class_name + " = " + int_to_string (t->id) + ",\n";
+      return "????\n";
+    } else {
+      return "";
+    }
+  }
+
+  std::string gen_additional_proxy_function_case(const std::string &function_name, const tl::tl_type *type,
+                                                 const tl::tl_combinator *t, int arity,
+                                                 bool is_function) const override {
+    if (is_header_ != (function_name == "enum" ? 1 : 0)) {
+      return "";
+    }
+
+    if (function_name == "TdDestroyObject" || function_name == "TdConvertToInternal" ||
+        function_name == "TdStackStorer") {
+      auto class_name = gen_class_name(t->name);
+      std::string extra_arg = "";
+      if (function_name == "TdStackStorer") {
+        extra_arg = ", M";
+      }
+      return "    case CODE_" + gen_class_name(t->name) + ": return " + function_name + " ((struct Td" + class_name +
+             " *)var" + extra_arg + ");\n";
+    } else if (function_name == "TdConvertFromInternal") {
+      const tl::tl_tree_type *tree_type = static_cast<const tl::tl_tree_type *>(t->result);
+
+      auto native_class_name = gen_native_class_name(t->name);
+      auto class_name = gen_main_class_name(tree_type->type);
+      if (type == nullptr) {
+        if (is_function) {
+          class_name = "Function";
+        } else {
+          class_name = "Object";
+        }
+      }
+      return "    case CODE_" + gen_class_name(t->name) + ": return (struct Td" + class_name + " *)" + function_name +
+             "(static_cast<const td::td_api::" + native_class_name + " &>(from));\n";
+    } else if (function_name == "enum") {
+      const tl::tl_tree_type *tree_type = static_cast<const tl::tl_tree_type *>(t->result);
+
+      auto native_class_name = gen_native_class_name(t->name);
+      auto class_name = gen_main_class_name(tree_type->type);
+      if (type == nullptr) {
+        if (is_function) {
+          class_name = "Function";
+        } else {
+          class_name = "Object";
+        }
+      }
+
+      int flat = 0;
+      if (!is_function) {
+        if (tree_type->type->constructors_num == 1) {
+          flat = 1;
+        }
+      }
+
+      if (class_name == "Object" && !flat) {
+        return "  CODE_Copy_" + gen_class_name(t->name) + " = " + int_to_string(t->id) + ",\n";
+      } else {
+        return "  CODE_" + gen_class_name(t->name) + " = " + int_to_string(t->id) + ",\n";
+      }
+    } else if (function_name == "TdStackFetcher") {
+      const tl::tl_tree_type *tree_type = static_cast<const tl::tl_tree_type *>(t->result);
+
+      auto native_class_name = gen_native_class_name(t->name);
+      auto class_name = gen_main_class_name(tree_type->type);
+      if (type == nullptr) {
+        if (is_function) {
+          class_name = "Function";
+        } else {
+          class_name = "Object";
+        }
+      }
+
+      return "if (constructor == \"" + gen_class_name(t->name) +
+             "\") {\n"
+             "    return (struct Td" +
+             class_name + " *)TdStackFetcher" + gen_class_name(t->name) +
+             " (M);\n"
+             "  }\n  ";
+    } else {
+      return "";
+    }
+  }
+  std::string gen_additional_proxy_function_end(const std::string &function_name, const tl::tl_type *type,
+                                                bool is_function) const override {
+    if (is_header_ != (function_name == "enum" ? 1 : 0)) {
+      return "";
+    }
+
+    if (function_name == "TdDestroyObject" || function_name == "TdConvertToInternal" ||
+        function_name == "TdConvertFromInternal" || function_name == "TdStackStorer") {
+      std::string retval = "";
+      if (function_name == "TdConvertToInternal" || function_name == "TdConvertFromInternal") {
+        retval = "nullptr";
+      }
+      return "    default:\n"
+             "      LOG(FATAL) << \"Unknown constructor found \" << td::format::as_hex(constructor);\n"
+             "      return " +
+             retval +
+             ";\n"
+             "  }\n"
+             "}\n";
+    } else if (function_name == "TdStackFetcher") {
+      return "{\n"
+             "    LOG(FATAL) << \"Unknown constructor found \" << constructor;\n"
+             "    return nullptr;\n"
+             "  }\n"
+             "}\n";
+    } else if (function_name == "enum") {
+      return "};\n";
+    } else {
+      return "";
+    }
+  }
+
+  int get_additional_function_type(const std::string &additional_function_name) const override {
+    return 2;
+  }
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_writer_cpp.cpp b/libs/tdlib/td/td/generate/tl_writer_cpp.cpp
new file mode 100644
index 0000000000..56a682c64b
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_writer_cpp.cpp
@@ -0,0 +1,666 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_writer_cpp.h"
+
+#include <cassert>
+
+namespace td {
+
+std::string TD_TL_writer_cpp::gen_output_begin() const {
+  std::string ext_include_str;
+  for (auto &it : ext_include) {
+    ext_include_str += "#include " + it + "\n";
+  }
+  if (!ext_include_str.empty()) {
+    ext_include_str += "\n";
+  }
+
+  return "#include \"" + tl_name + ".h\"\n\n" + ext_include_str +
+         "#include \"td/utils/common.h\"\n"
+         "#include \"td/utils/format.h\"\n"
+         "#include \"td/utils/logging.h\"\n"
+         "#include \"td/utils/tl_parsers.h\"\n"
+         "#include \"td/utils/tl_storers.h\"\n\n"
+         "namespace td {\n"
+         "namespace " +
+         tl_name +
+         " {\n\n"
+         "std::string to_string(const BaseObject &value) {\n"
+         "  TlStorerToString storer;\n"
+         "  value.store(storer, \"\");\n"
+         "  return storer.str();\n"
+         "}\n";
+}
+
+std::string TD_TL_writer_cpp::gen_output_end() const {
+  return "}  // namespace " + tl_name +
+         "\n"
+         "}  // namespace td\n";
+}
+
+std::string TD_TL_writer_cpp::gen_field_definition(const std::string &class_name, const std::string &type_name,
+                                                   const std::string &field_name) const {
+  return "";
+}
+
+std::string TD_TL_writer_cpp::gen_vars(const tl::tl_combinator *t, const tl::tl_tree_type *result_type,
+                                       std::vector<tl::var_description> &vars) const {
+  for (std::size_t i = 0; i < vars.size(); i++) {
+    vars[i].index = static_cast<int>(i);
+    vars[i].is_stored = false;
+    vars[i].is_type = false;
+    vars[i].parameter_num = -1;
+    vars[i].function_arg_num = -1;
+  }
+
+  if (result_type != nullptr) {
+    assert(result_type->children.empty());
+  }
+
+  for (std::size_t i = 0; i < t->args.size(); i++) {
+    const tl::arg &a = t->args[i];
+
+    int arg_type = a.type->get_type();
+    if (arg_type == tl::NODE_TYPE_VAR_TYPE) {
+      const tl::tl_tree_var_type *var_type = static_cast<const tl::tl_tree_var_type *>(a.type);
+      assert(a.flags & tl::FLAG_EXCL);
+      assert(var_type->var_num < static_cast<int>(vars.size()));
+      assert(var_type->var_num >= 0);
+      assert(!vars[var_type->var_num].is_type);
+      vars[var_type->var_num].is_type = true;
+      vars[var_type->var_num].function_arg_num = static_cast<int>(i);
+    }
+  }
+
+  std::string res;
+  for (std::size_t i = 0; i < vars.size(); i++) {
+    if (!vars[i].is_type) {
+      assert(vars[i].parameter_num == -1);
+      assert(vars[i].function_arg_num == -1);
+      assert(vars[i].is_stored == false);
+      res += "  " + gen_class_name("#") + " " + gen_var_name(vars[i]) + ";\n";
+    }
+  }
+  return res;
+}
+
+std::string TD_TL_writer_cpp::gen_function_vars(const tl::tl_combinator *t,
+                                                std::vector<tl::var_description> &vars) const {
+  for (std::size_t i = 0; i < vars.size(); i++) {
+    vars[i].index = static_cast<int>(i);
+    vars[i].is_stored = false;
+    vars[i].is_type = false;
+    vars[i].parameter_num = -1;
+    vars[i].function_arg_num = -1;
+  }
+
+  for (std::size_t i = 0; i < t->args.size(); i++) {
+    const tl::arg &a = t->args[i];
+
+    int arg_type = a.type->get_type();
+    if (arg_type == tl::NODE_TYPE_VAR_TYPE) {
+      const tl::tl_tree_var_type *var_type = static_cast<const tl::tl_tree_var_type *>(a.type);
+      assert(a.flags & tl::FLAG_EXCL);
+      assert(var_type->var_num >= 0);
+      assert(!vars[var_type->var_num].is_type);
+      vars[var_type->var_num].is_type = true;
+      vars[var_type->var_num].function_arg_num = static_cast<int>(i);
+    }
+  }
+
+  return "";
+}
+
+std::string TD_TL_writer_cpp::gen_uni(const tl::tl_tree_type *result_type, std::vector<tl::var_description> &vars,
+                                      bool check_negative) const {
+  assert(result_type->children.empty());
+  return "";
+}
+
+std::string TD_TL_writer_cpp::gen_constructor_id_store_raw(const std::string &id) const {
+  return "s.store_binary(" + id + ");";
+}
+
+std::string TD_TL_writer_cpp::gen_constructor_id_store(std::int32_t id, int storer_type) const {
+  if (storer_type == 1) {
+    return "";
+  }
+  return "  " + gen_constructor_id_store_raw(int_to_string(id)) + "\n";
+}
+
+std::string TD_TL_writer_cpp::gen_fetch_class_name(const tl::tl_tree_type *tree_type) const {
+  const tl::tl_type *t = tree_type->type;
+  const std::string &name = t->name;
+
+  if (name == "#" || name == "Int32") {
+    return "TlFetchInt";
+  }
+  if (name == "Int53" || name == "Int64") {
+    return "TlFetchLong";
+  }
+  if (name == "True" || name == "Bool" || name == "Int" || name == "Long" || name == "Double" || name == "Int128" ||
+      name == "Int256") {
+    return "TlFetch" + name;
+  }
+  if (name == "String") {
+    return "TlFetchString<" + string_type + ">";
+  }
+  if (name == "Bytes") {
+    return "TlFetchBytes<" + bytes_type + ">";
+  }
+
+  if (name == "Vector") {
+    assert(t->arity == 1);
+    assert(tree_type->children.size() == 1);
+    assert(tree_type->children[0]->get_type() == tl::NODE_TYPE_TYPE);
+    const tl::tl_tree_type *child = static_cast<const tl::tl_tree_type *>(tree_type->children[0]);
+
+    return "TlFetchVector<" + gen_full_fetch_class_name(child) + ">";
+  }
+
+  assert(!is_built_in_simple_type(name) && !is_built_in_complex_type(name));
+  for (std::size_t i = 0; i < tree_type->children.size(); i++) {
+    assert(tree_type->children[i]->get_type() == tl::NODE_TYPE_NAT_CONST);
+  }
+
+  assert(tree_type->children.empty());
+  return "TlFetchObject<" + gen_main_class_name(t) + ">";
+}
+
+std::string TD_TL_writer_cpp::gen_full_fetch_class_name(const tl::tl_tree_type *tree_type) const {
+  const tl::tl_type *t = tree_type->type;
+  const std::string &name = t->name;
+
+  assert(!(t->flags & tl::FLAG_DEFAULT_CONSTRUCTOR));  // Not supported yet
+
+  std::int32_t expected_constructor_id = 0;
+  if (tree_type->flags & tl::FLAG_BARE) {
+    assert(is_type_bare(t));
+  } else {
+    if (is_type_bare(t)) {
+      for (std::size_t i = 0; i < t->constructors_num; i++) {
+        if (is_built_in_complex_type(name) || is_combinator_supported(t->constructors[i])) {
+          assert(expected_constructor_id == 0);
+          expected_constructor_id = t->constructors[i]->id;
+          assert(expected_constructor_id != 0);
+        }
+      }
+    }
+  }
+  if (expected_constructor_id == 0) {
+    return gen_fetch_class_name(tree_type);
+  }
+  return "TlFetchBoxed<" + gen_fetch_class_name(tree_type) + ", " + int_to_string(expected_constructor_id) + ">";
+}
+
+std::string TD_TL_writer_cpp::gen_type_fetch(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                                             const std::vector<tl::var_description> &vars, int parser_type) const {
+  return gen_full_fetch_class_name(tree_type) + "::parse(p)";
+}
+
+std::string TD_TL_writer_cpp::gen_field_fetch(int field_num, const tl::arg &a, std::vector<tl::var_description> &vars,
+                                              bool flat, int parser_type) const {
+  assert(parser_type >= 0);
+  std::string field_name = (parser_type == 0 ? (field_num == 0 ? ": " : ", ") : "res->") + gen_field_name(a.name);
+
+  if (a.type->get_type() == tl::NODE_TYPE_VAR_TYPE) {
+    assert(parser_type == 1);
+
+    const tl::tl_tree_var_type *t = static_cast<const tl::tl_tree_var_type *>(a.type);
+    assert(a.flags == tl::FLAG_EXCL);
+
+    assert(a.var_num == -1);
+    assert(a.exist_var_num == -1);
+
+    assert(t->var_num >= 0);
+    assert(vars[t->var_num].is_type);
+    assert(!vars[t->var_num].is_stored);
+    vars[t->var_num].is_stored = true;
+
+    return "  " + field_name + " = " + gen_base_function_class_name() + "::fetch(p);\n";
+  }
+
+  assert(!(a.flags & tl::FLAG_EXCL));
+
+  assert(!(a.flags & tl::FLAG_OPT_VAR));
+
+  std::string res = "  ";
+  if (a.exist_var_num != -1) {
+    assert(0 <= a.exist_var_num && a.exist_var_num < static_cast<int>(vars.size()));
+    assert(vars[a.exist_var_num].is_stored);
+
+    res += "if (" + gen_var_name(vars[a.exist_var_num]) + " & " + int_to_string(1 << a.exist_var_bit) + ") { ";
+  }
+
+  if (flat) {
+    //    TODO
+    //    return gen_field_fetch(const tl::arg &a, std::vector<tl::var_description> &vars, int num, bool flat);
+  }
+
+  bool store_to_var_num = false;
+  if (a.var_num >= 0) {
+    assert(a.type->get_type() == tl::NODE_TYPE_TYPE);
+    assert(static_cast<const tl::tl_tree_type *>(a.type)->type->id == tl::ID_VAR_NUM);
+    assert(0 <= a.var_num && a.var_num < static_cast<int>(vars.size()));
+    if (!vars[a.var_num].is_stored) {
+      res += "if ((" + gen_var_name(vars[a.var_num]) + " = ";
+      store_to_var_num = true;
+    } else {
+      assert(false);
+    }
+    vars[a.var_num].is_stored = true;
+  }
+
+  res += field_name + (parser_type == 0 ? "(" : " = ");
+
+  assert(a.type->get_type() == tl::NODE_TYPE_TYPE);
+  const tl::tl_tree_type *tree_type = static_cast<tl::tl_tree_type *>(a.type);
+  res += gen_type_fetch(field_name, tree_type, vars, parser_type);
+  if (store_to_var_num) {
+    res += ") < 0) { FAIL(\"Variable of type # can't be negative\"); }";
+  } else {
+    res += (parser_type == 0 ? ")" : ";");
+  }
+
+  if (a.exist_var_num >= 0) {
+    res += " }";
+    if (store_to_var_num) {
+      res += " else { " + gen_var_name(vars[a.var_num]) + " = 0; }";
+    }
+  }
+  res += "\n";
+  return res;
+}
+
+std::string TD_TL_writer_cpp::gen_var_type_fetch(const tl::arg &a) const {
+  assert(false);
+  return "";
+}
+
+std::string TD_TL_writer_cpp::get_pretty_field_name(std::string field_name) const {
+  if (!field_name.empty() && field_name.back() == ']') {
+    return "";
+  }
+  auto equals_pos = field_name.find('=');
+  if (equals_pos != std::string::npos && equals_pos + 3 < field_name.size()) {
+    field_name = field_name.substr(equals_pos + 2);
+    if (field_name.back() == ')') {
+      field_name.pop_back();
+    }
+  }
+  while (!field_name.empty() && field_name.back() == '_') {
+    field_name.pop_back();
+  }
+  return field_name;
+}
+
+std::string TD_TL_writer_cpp::get_pretty_class_name(std::string class_name) const {
+  return class_name;
+}
+
+std::string TD_TL_writer_cpp::gen_vector_store(const std::string &field_name, const tl::tl_tree_type *t,
+                                               const std::vector<tl::var_description> &vars, int storer_type) const {
+  std::string num = field_name.back() == ']' ? "2" : "";
+  return "{ const std::vector<" + gen_type_name(t) + "> &v" + num + " = " + field_name +
+         "; const std::uint32_t multiplicity" + num + " = static_cast<std::uint32_t>(v" + num +
+         ".size()); const auto vector_name" + num + " = \"" + get_pretty_class_name("vector") +
+         "[\" + td::to_string(multiplicity" + num + ")+ \"]\"; s.store_class_begin(\"" +
+         get_pretty_field_name(field_name) + "\", vector_name" + num +
+         ".c_str()); "
+         "for (std::uint32_t i" +
+         num + " = 0; i" + num + " < multiplicity" + num + "; i" + num + "++) { " +
+         gen_type_store("v" + num + "[i" + num + "]", t, vars, storer_type) + " } s.store_class_end(); }";
+}
+
+std::string TD_TL_writer_cpp::gen_store_class_name(const tl::tl_tree_type *tree_type) const {
+  const tl::tl_type *t = tree_type->type;
+  const std::string &name = t->name;
+
+  if (name == "#" || name == "Int" || name == "Long" || name == "Int32" || name == "Int53" || name == "Int64" ||
+      name == "Double" || name == "Int128" || name == "Int256") {
+    return "TlStoreBinary";
+  }
+  if (name == "Bool") {
+    return "TlStoreBool";
+  }
+  if (name == "True") {
+    return "TlStoreTrue";
+  }
+  if (name == "String" || name == "Bytes") {
+    return "TlStoreString";
+  }
+
+  if (name == "Vector") {
+    assert(t->arity == 1);
+    assert(tree_type->children.size() == 1);
+    assert(tree_type->children[0]->get_type() == tl::NODE_TYPE_TYPE);
+    const tl::tl_tree_type *child = static_cast<const tl::tl_tree_type *>(tree_type->children[0]);
+
+    return "TlStoreVector<" + gen_full_store_class_name(child) + ">";
+  }
+
+  assert(!is_built_in_simple_type(name) && !is_built_in_complex_type(name));
+  for (std::size_t i = 0; i < tree_type->children.size(); i++) {
+    assert(tree_type->children[i]->get_type() == tl::NODE_TYPE_NAT_CONST);
+  }
+
+  assert(tree_type->children.empty());
+  return "TlStoreObject";
+}
+
+std::string TD_TL_writer_cpp::gen_full_store_class_name(const tl::tl_tree_type *tree_type) const {
+  const tl::tl_type *t = tree_type->type;
+
+  assert(!(t->flags & tl::FLAG_DEFAULT_CONSTRUCTOR));  // Not supported yet
+
+  if ((tree_type->flags & tl::FLAG_BARE) != 0 || t->name == "#" || t->name == "Bool") {
+    return gen_store_class_name(tree_type);
+  }
+
+  if (is_built_in_complex_type(t->name)) {
+    return "TlStoreBoxed<" + gen_store_class_name(tree_type) + ", " + int_to_string(t->constructors[0]->id) + ">";
+  }
+
+  if (!is_type_bare(t)) {
+    return "TlStoreBoxedUnknown<" + gen_store_class_name(tree_type) + ">";
+  }
+
+  for (std::size_t i = 0; i < t->constructors_num; i++) {
+    if (is_combinator_supported(t->constructors[i])) {
+      return "TlStoreBoxed<" + gen_store_class_name(tree_type) + ", " + int_to_string(t->constructors[i]->id) + ">";
+    }
+  }
+
+  assert(false);
+  return "";
+}
+
+std::string TD_TL_writer_cpp::gen_type_store(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                                             const std::vector<tl::var_description> &vars, int storer_type) const {
+  if (storer_type == 0) {
+    return gen_full_store_class_name(tree_type) + "::store(" + field_name + ", s);";
+  }
+
+  const tl::tl_type *t = tree_type->type;
+  const std::string &name = t->name;
+
+  assert(!(t->flags & tl::FLAG_DEFAULT_CONSTRUCTOR));  // Not supported yet
+
+  if (name == "#" || name == "Int" || name == "Long" || name == "Int32" || name == "Int53" || name == "Int64" ||
+      name == "Double" || name == "Bool" || name == "String" || name == "Int128" || name == "Int256") {
+    return "s.store_field(\"" + get_pretty_field_name(field_name) + "\", " + field_name + ");";
+  } else if (name == "True") {
+    // currently nothing to do
+    return "";
+  } else if (name == "Bytes") {
+    return "s.store_bytes_field(\"" + get_pretty_field_name(field_name) + "\", " + field_name + ");";
+  } else if (name == "Vector") {
+    const tl::tl_tree_type *child = static_cast<const tl::tl_tree_type *>(tree_type->children[0]);
+    return gen_vector_store(field_name, child, vars, storer_type);
+  } else {
+    assert(tree_type->children.empty());
+    return "if (" + field_name + " == nullptr) { s.store_field(\"" + get_pretty_field_name(field_name) +
+           "\", \"null\"); } else { " + field_name + "->store(s, \"" + get_pretty_field_name(field_name) + "\"); }";
+  }
+}
+
+std::string TD_TL_writer_cpp::gen_field_store(const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                                              int storer_type) const {
+  std::string field_name = gen_field_name(a.name);
+  std::string res = storer_type == 1 ? "    " : "  ";
+
+  if (a.type->get_type() == tl::NODE_TYPE_VAR_TYPE) {
+    const tl::tl_tree_var_type *t = static_cast<const tl::tl_tree_var_type *>(a.type);
+    assert(a.flags == tl::FLAG_EXCL);
+
+    assert(a.var_num == -1);
+    assert(a.exist_var_num == -1);
+
+    assert(t->var_num >= 0);
+    assert(!vars[t->var_num].is_stored);
+    vars[t->var_num].is_stored = true;
+    assert(vars[t->var_num].is_type);
+
+    return res + field_name + "->store(s);\n";
+  }
+
+  assert(!(a.flags & tl::FLAG_EXCL));
+
+  if (a.flags & tl::FLAG_OPT_VAR) {
+    assert(false);
+    assert(a.exist_var_num == -1);
+    assert(0 <= a.var_num && a.var_num < static_cast<int>(vars.size()));
+
+    assert(a.type->get_type() == tl::NODE_TYPE_TYPE);
+    assert(static_cast<const tl::tl_tree_type *>(a.type)->type->id == tl::ID_VAR_NUM);
+    assert(vars[a.var_num].is_stored);
+    assert(!vars[a.var_num].is_type);
+    return "";
+  }
+
+  if (a.exist_var_num >= 0) {
+    assert(a.exist_var_num < static_cast<int>(vars.size()));
+    assert(vars[a.exist_var_num].is_stored);
+
+    res += "if (" + gen_var_name(vars[a.exist_var_num]) + " & " + int_to_string(1 << a.exist_var_bit) + ") { ";
+  }
+
+  if (flat) {
+    //    TODO
+    //    return gen_field_store(const tl::arg &a, std::vector<tl::var_description> &vars, bool flat, int storer_type);
+  }
+
+  if (a.var_num >= 0) {
+    assert(a.type->get_type() == tl::NODE_TYPE_TYPE);
+    assert(static_cast<const tl::tl_tree_type *>(a.type)->type->id == tl::ID_VAR_NUM);
+    assert(a.var_num < static_cast<int>(vars.size()));
+    if (!vars[a.var_num].is_stored) {
+      field_name = "(" + gen_var_name(vars[a.var_num]) + " = " + field_name + ")";
+      vars[a.var_num].is_stored = true;
+    } else {
+      assert(false);  // need to check value of stored var
+      field_name = gen_var_name(vars[a.var_num]);
+    }
+  }
+
+  assert(a.type->get_type() == tl::NODE_TYPE_TYPE);
+  const tl::tl_tree_type *tree_type = static_cast<tl::tl_tree_type *>(a.type);
+  res += gen_type_store(field_name, tree_type, vars, storer_type);
+  if (a.exist_var_num >= 0) {
+    res += " }";
+  }
+  res += "\n";
+  return res;
+}
+
+std::string TD_TL_writer_cpp::gen_forward_class_declaration(const std::string &class_name, bool is_proxy) const {
+  return "";
+}
+
+std::string TD_TL_writer_cpp::gen_class_begin(const std::string &class_name, const std::string &base_class_name,
+                                              bool is_proxy) const {
+  return "";
+}
+
+std::string TD_TL_writer_cpp::gen_class_end() const {
+  return "";
+}
+
+std::string TD_TL_writer_cpp::gen_class_alias(const std::string &class_name, const std::string &alias_name) const {
+  return "";
+}
+
+std::string TD_TL_writer_cpp::gen_get_id(const std::string &class_name, std::int32_t id, bool is_proxy) const {
+  if (is_proxy) {
+    return "";
+  }
+  return "\nconst std::int32_t " + class_name + "::ID;\n";
+}
+
+std::string TD_TL_writer_cpp::gen_function_result_type(const tl::tl_tree *result) const {
+  return "";
+}
+
+std::string TD_TL_writer_cpp::gen_fetch_function_begin(const std::string &parser_name, const std::string &class_name,
+                                                       int arity, std::vector<tl::var_description> &vars,
+                                                       int parser_type) const {
+  for (std::size_t i = 0; i < vars.size(); i++) {
+    assert(vars[i].is_stored == false);
+  }
+
+  std::string fetched_type = "object_ptr<" + class_name + "> ";
+  assert(arity == 0);
+
+  if (parser_type == 0) {
+    return "\n" + class_name + "::" + class_name + "(" + parser_name +
+           " &p)\n"
+           "#define FAIL(error) p.set_error(error)\n";
+  }
+
+  return "\n" + fetched_type + class_name + "::fetch(" + parser_name +
+         " &p) {\n"
+         "#define FAIL(error) p.set_error(error); return nullptr;\n" +
+         (parser_type == -1 ? "" : "  " + fetched_type + "res = make_tl_object<" + class_name + ">();\n");
+}
+
+std::string TD_TL_writer_cpp::gen_fetch_function_end(int field_num, const std::vector<tl::var_description> &vars,
+                                                     int parser_type) const {
+  for (std::size_t i = 0; i < vars.size(); i++) {
+    assert(vars[i].is_stored);
+  }
+
+  if (parser_type == 0) {
+    return "#undef FAIL\n"
+           "{" +
+           (field_num == 0 ? "\n  (void)p;\n" : std::string()) + "}\n";
+  }
+
+  if (parser_type == -1) {
+    return "#undef FAIL\n"
+           "}\n";
+  }
+
+  return "  if (p.get_error()) { FAIL(\"\"); }\n"
+         "  return res;\n"
+         "#undef FAIL\n"
+         "}\n";
+}
+
+std::string TD_TL_writer_cpp::gen_fetch_function_result_begin(const std::string &parser_name,
+                                                              const std::string &class_name,
+                                                              const tl::tl_tree *result) const {
+  return "\n" + class_name + "::ReturnType " + class_name + "::fetch_result(" + parser_name +
+         " &p) {\n"
+         "#define FAIL(error) p.set_error(error); return ReturnType()\n"
+         "  return ";
+}
+
+std::string TD_TL_writer_cpp::gen_fetch_function_result_end() const {
+  return ";\n"
+         "#undef FAIL\n"
+         "}\n";
+}
+
+std::string TD_TL_writer_cpp::gen_fetch_function_result_any_begin(const std::string &parser_name,
+                                                                  const std::string &class_name, bool is_proxy) const {
+  return "";
+}
+
+std::string TD_TL_writer_cpp::gen_fetch_function_result_any_end(bool is_proxy) const {
+  return "";
+}
+
+std::string TD_TL_writer_cpp::gen_store_function_begin(const std::string &storer_name, const std::string &class_name,
+                                                       int arity, std::vector<tl::var_description> &vars,
+                                                       int storer_type) const {
+  for (std::size_t i = 0; i < vars.size(); i++) {
+    vars[i].is_stored = false;
+  }
+
+  if (storer_type == -1) {
+    return "";
+  }
+
+  assert(arity == 0);
+  return "\n"
+         "void " +
+         class_name + "::store(" + storer_name + " &s" +
+         std::string(storer_type <= 0 ? "" : ", const char *field_name") + ") const {\n" +
+         (storer_type <= 0 ? "  (void)sizeof(s);\n"
+                           : "  if (!LOG_IS_STRIPPED(ERROR)) {\n"
+                             "    s.store_class_begin(field_name, \"" +
+                                 get_pretty_class_name(class_name) + "\");\n");
+}
+
+std::string TD_TL_writer_cpp::gen_store_function_end(const std::vector<tl::var_description> &vars,
+                                                     int storer_type) const {
+  for (std::size_t i = 0; i < vars.size(); i++) {
+    assert(vars[i].is_stored);
+  }
+
+  if (storer_type == -1) {
+    return "";
+  }
+
+  return (storer_type <= 0 ? std::string()
+                           : "    s.store_class_end();\n"
+                             "  }\n") +
+         "}\n";
+}
+
+std::string TD_TL_writer_cpp::gen_fetch_switch_begin() const {
+  return "  int constructor = p.fetch_int();\n"
+         "  switch (constructor) {\n";
+}
+
+std::string TD_TL_writer_cpp::gen_fetch_switch_case(const tl::tl_combinator *t, int arity) const {
+  assert(arity == 0);
+  return "    case " + gen_class_name(t->name) +
+         "::ID:\n"
+         "      return " +
+         gen_class_name(t->name) + "::fetch(p);\n";
+}
+
+std::string TD_TL_writer_cpp::gen_fetch_switch_end() const {
+  return "    default:\n"
+         "      FAIL(PSTRING() << \"Unknown constructor found \" << format::as_hex(constructor));\n"
+         "  }\n";
+}
+
+std::string TD_TL_writer_cpp::gen_constructor_begin(int fields_num, const std::string &class_name,
+                                                    bool is_default) const {
+  return "\n" + class_name + "::" + class_name + "(";
+}
+
+std::string TD_TL_writer_cpp::gen_constructor_field_init(int field_num, const std::string &class_name, const tl::arg &a,
+                                                         bool is_default) const {
+  std::string field_type = gen_field_type(a);
+  if (field_type.empty()) {
+    return "";
+  }
+  std::string move_begin;
+  std::string move_end;
+  if ((field_type == bytes_type || field_type.compare(0, 11, "std::vector") == 0 ||
+       field_type.compare(0, 10, "object_ptr") == 0) &&
+      !is_default) {
+    move_begin = "std::move(";
+    move_end = ")";
+  }
+
+  return (field_num == 0 ? ")\n  : " : "  , ") + gen_field_name(a.name) + "(" + move_begin +
+         (is_default ? "" : gen_field_name(a.name)) + move_end + ")\n";
+}
+
+std::string TD_TL_writer_cpp::gen_constructor_end(const tl::tl_combinator *t, int fields_num, bool is_default) const {
+  if (fields_num == 0) {
+    return ") {\n"
+           "}\n";
+  }
+  return "{}\n";
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_writer_cpp.h b/libs/tdlib/td/td/generate/tl_writer_cpp.h
new file mode 100644
index 0000000000..eb64d18a88
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_writer_cpp.h
@@ -0,0 +1,105 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "tl_writer_td.h"
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+namespace td {
+
+class TD_TL_writer_cpp : public TD_TL_writer {
+  std::string gen_constructor_id_store_raw(const std::string &id) const;
+
+  std::string gen_fetch_class_name(const tl::tl_tree_type *tree_type) const;
+
+  std::string gen_full_fetch_class_name(const tl::tl_tree_type *tree_type) const;
+
+  std::string gen_store_class_name(const tl::tl_tree_type *tree_type) const;
+
+  std::string gen_full_store_class_name(const tl::tl_tree_type *tree_type) const;
+
+  std::vector<std::string> ext_include;
+
+ protected:
+  std::string gen_vector_store(const std::string &field_name, const tl::tl_tree_type *t,
+                               const std::vector<tl::var_description> &vars, int storer_type) const;
+
+  virtual std::string get_pretty_field_name(std::string field_name) const;
+
+  virtual std::string get_pretty_class_name(std::string class_name) const;
+
+ public:
+  TD_TL_writer_cpp(const std::string &tl_name, const std::string &string_type, const std::string &bytes_type,
+                   const std::vector<std::string> &ext_include)
+      : TD_TL_writer(tl_name, string_type, bytes_type), ext_include(ext_include) {
+  }
+
+  std::string gen_output_begin() const override;
+  std::string gen_output_end() const override;
+
+  std::string gen_forward_class_declaration(const std::string &class_name, bool is_proxy) const override;
+
+  std::string gen_class_begin(const std::string &class_name, const std::string &base_class_name,
+                              bool is_proxy) const override;
+  std::string gen_class_end() const override;
+
+  std::string gen_class_alias(const std::string &class_name, const std::string &alias_name) const override;
+
+  std::string gen_field_definition(const std::string &class_name, const std::string &type_name,
+                                   const std::string &field_name) const override;
+
+  std::string gen_vars(const tl::tl_combinator *t, const tl::tl_tree_type *result_type,
+                       std::vector<tl::var_description> &vars) const override;
+  std::string gen_function_vars(const tl::tl_combinator *t, std::vector<tl::var_description> &vars) const override;
+  std::string gen_uni(const tl::tl_tree_type *result_type, std::vector<tl::var_description> &vars,
+                      bool check_negative) const override;
+  std::string gen_constructor_id_store(std::int32_t id, int storer_type) const override;
+
+  std::string gen_field_fetch(int field_num, const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                              int parser_type) const override;
+  std::string gen_field_store(const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                              int storer_type) const override;
+  std::string gen_type_fetch(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                             const std::vector<tl::var_description> &vars, int parser_type) const override;
+  std::string gen_type_store(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                             const std::vector<tl::var_description> &vars, int storer_type) const override;
+  std::string gen_var_type_fetch(const tl::arg &a) const override;
+
+  std::string gen_get_id(const std::string &class_name, std::int32_t id, bool is_proxy) const override;
+
+  std::string gen_function_result_type(const tl::tl_tree *result) const override;
+
+  std::string gen_fetch_function_begin(const std::string &parser_name, const std::string &class_name, int arity,
+                                       std::vector<tl::var_description> &vars, int parser_type) const override;
+  std::string gen_fetch_function_end(int field_num, const std::vector<tl::var_description> &vars,
+                                     int parser_type) const override;
+
+  std::string gen_fetch_function_result_begin(const std::string &parser_name, const std::string &class_name,
+                                              const tl::tl_tree *result) const override;
+  std::string gen_fetch_function_result_end() const override;
+  std::string gen_fetch_function_result_any_begin(const std::string &parser_name, const std::string &class_name,
+                                                  bool is_proxy) const override;
+  std::string gen_fetch_function_result_any_end(bool is_proxy) const override;
+
+  std::string gen_store_function_begin(const std::string &storer_name, const std::string &class_name, int arity,
+                                       std::vector<tl::var_description> &vars, int storer_type) const override;
+  std::string gen_store_function_end(const std::vector<tl::var_description> &vars, int storer_type) const override;
+
+  std::string gen_fetch_switch_begin() const override;
+  std::string gen_fetch_switch_case(const tl::tl_combinator *t, int arity) const override;
+  std::string gen_fetch_switch_end() const override;
+
+  std::string gen_constructor_begin(int fields_num, const std::string &class_name, bool is_default) const override;
+  std::string gen_constructor_field_init(int field_num, const std::string &class_name, const tl::arg &a,
+                                         bool is_default) const override;
+  std::string gen_constructor_end(const tl::tl_combinator *t, int fields_num, bool is_default) const override;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_writer_dotnet.h b/libs/tdlib/td/td/generate/tl_writer_dotnet.h
new file mode 100644
index 0000000000..8228fa2334
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_writer_dotnet.h
@@ -0,0 +1,551 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/tl/tl_writer.h"
+
+#include <cassert>
+#include <cstdint>
+#include <sstream>
+#include <string>
+#include <vector>
+
+namespace td {
+namespace tl {
+
+class TlWriterDotNet : public TL_writer {
+ public:
+  bool is_header_;
+  std::string prefix_;
+  TlWriterDotNet(const std::string &name, bool is_header, const std::string &prefix = "")
+      : TL_writer(name), is_header_(is_header), prefix_(prefix) {
+  }
+  int get_max_arity(void) const override {
+    return 0;
+  }
+
+  bool is_built_in_simple_type(const std::string &name) const override {
+    return name == "Bool" || name == "Int32" || name == "Int53" || name == "Int64" || name == "Double" || name == "String" || name == "Bytes";
+  }
+  bool is_built_in_complex_type(const std::string &name) const override {
+    return name == "Vector";
+  }
+  bool is_type_bare(const tl_type *t) const override {
+    return t->simple_constructors <= 1 || (is_built_in_simple_type(t->name) && t->name != "Bool") ||
+           is_built_in_complex_type(t->name);
+  }
+
+  std::vector<std::string> get_parsers(void) const override {
+    return {"FromUnmanaged"};
+  }
+  int get_parser_type(const tl_combinator *t, const std::string &name) const override {
+    return 0;
+  }
+  Mode get_parser_mode(int type) const override {
+    return All;  // Server;
+  }
+  std::vector<std::string> get_storers(void) const override {
+    return {"ToUnmanaged", "ToString"};
+  }
+  std::vector<std::string> get_additional_functions(void) const override {
+    return {"ToUnmanaged", "FromUnmanaged"};
+  }
+  int get_storer_type(const tl_combinator *t, const std::string &name) const override {
+    return name == "ToString";
+  }
+  Mode get_storer_mode(int type) const override {
+    return type <= 1 ? All : Server;
+  }
+
+  std::string gen_base_tl_class_name(void) const override {
+    return "BaseObject";
+  }
+  std::string gen_base_type_class_name(int arity) const override {
+    assert(arity == 0);
+    return "Object";
+  }
+  std::string gen_base_function_class_name(void) const override {
+    return "Function";
+  }
+
+  static std::string to_camelCase(const std::string &name) {
+    return to_cCamelCase(name, false);
+  }
+  static std::string to_CamelCase(const std::string &name) {
+    return to_cCamelCase(name, true);
+  }
+  static std::string to_cCamelCase(const std::string &name, bool flag) {
+    bool next_to_upper = flag;
+    std::string result;
+    for (int i = 0; i < (int)name.size(); i++) {
+      if (!is_alnum(name[i])) {
+        next_to_upper = true;
+        continue;
+      }
+      if (next_to_upper) {
+        result += (char)to_upper(name[i]);
+        next_to_upper = false;
+      } else {
+        result += name[i];
+      }
+    }
+    return result;
+  }
+
+  std::string gen_native_field_name(std::string name) const {
+    for (int i = 0; i < (int)name.size(); i++) {
+      if (!is_alnum(name[i])) {
+        name[i] = '_';
+      }
+    }
+    assert(name.size() > 0);
+    assert(name[name.size() - 1] != '_');
+    return name + "_";
+  }
+
+  std::string gen_native_class_name(std::string name) const {
+    if (name == "Object") {
+      assert(0);
+    }
+    if (name == "#") {
+      return "int32_t";
+    }
+    for (int i = 0; i < (int)name.size(); i++) {
+      if (!is_alnum(name[i])) {
+        name[i] = '_';
+      }
+    }
+    return name;
+  }
+
+  std::string gen_class_name(std::string name) const override {
+    if (name == "Object" || name == "#") {
+      assert(0);
+    }
+    return to_CamelCase(name);
+  }
+  std::string gen_field_name(std::string name) const override {
+    assert(name.size() > 0);
+    assert(is_alnum(name.back()));
+    return to_CamelCase(name);
+  }
+
+  std::string gen_type_name(const tl_tree_type *tree_type) const override {
+    const tl_type *t = tree_type->type;
+    const std::string &name = t->name;
+
+    if (name == "#") {
+      assert(0);
+    }
+    if (name == "Bool") {
+      return "bool";
+    }
+    if (name == "Int32") {
+      return "int32";
+    }
+    if (name == "Int53" || name == "Int64") {
+      return "int64";
+    }
+    if (name == "Double") {
+      return "float64";
+    }
+    if (name == "String") {
+      return "String^";
+    }
+    if (name == "Bytes") {
+      return "Array<byte>^";
+    }
+
+    if (name == "Vector") {
+      assert(t->arity == 1);
+      assert((int)tree_type->children.size() == 1);
+      assert(tree_type->children[0]->get_type() == NODE_TYPE_TYPE);
+      const tl_tree_type *child = static_cast<const tl_tree_type *>(tree_type->children[0]);
+
+      return "Array<" + gen_type_name(child) + ">^";
+    }
+
+    assert(!is_built_in_simple_type(name) && !is_built_in_complex_type(name));
+
+    for (int i = 0; i < (int)tree_type->children.size(); i++) {
+      assert(tree_type->children[i]->get_type() == NODE_TYPE_NAT_CONST);
+    }
+
+    return gen_main_class_name(t) + "^";
+  }
+  std::string gen_output_begin(void) const override {
+    return prefix_ +
+           "#include \"td/tl/tl_dotnet_object.h\"\n\n"
+           "namespace Telegram {\n"
+           "namespace Td {\n"
+           "namespace Api {\n";
+  }
+  std::string gen_output_end() const override {
+    return "}\n"
+           "}\n"
+           "}\n";
+  }
+
+  std::string gen_forward_class_declaration(const std::string &class_name, bool is_proxy) const override {
+    if (!is_header_) {
+      return "";
+    }
+    std::stringstream ss;
+    ss << (is_proxy ? "interface" : "ref") << " class " << class_name << ";\n";
+    return ss.str();
+  }
+
+  std::string gen_class_begin(const std::string &class_name, const std::string &base_class_name,
+                              bool is_proxy) const override {
+    if (!is_header_) {
+      return "";
+    }
+
+    std::stringstream ss;
+    ss << "\npublic " << (is_proxy ? "interface" : "ref") << " class " << class_name << (is_proxy ? "" : " sealed")
+       << (class_name == gen_base_tl_class_name() ? "" : " : " + base_class_name) << " {\n"
+       << " public:\n";
+    return ss.str();
+  }
+  std::string gen_class_end(void) const override {
+    return "";
+  }
+
+  std::string gen_field_definition(const std::string &class_name, const std::string &type_name,
+                                   const std::string &field_name) const override {
+    if (!is_header_) {
+      return "";
+    }
+    auto fixed_field_name = field_name;
+    if (field_name == class_name) {
+      fixed_field_name += "Value";
+    }
+    if (type_name.substr(0, field_name.size()) == field_name) {
+      auto fixed_type_name = "::Telegram::Td::Api::" + type_name;
+      std::stringstream ss;
+      ss << "private:\n";
+      ss << "  " << fixed_type_name << " " << fixed_field_name << "PrivateField;\n";
+      ss << "public:\n";
+      ss << "  property " << fixed_type_name << " " << fixed_field_name << " {\n";
+      ss << "    " << fixed_type_name << " get() {\n";
+      ss << "      return " << fixed_field_name << "PrivateField;\n";
+      ss << "    }\n";
+      ss << "    void set(" << fixed_type_name << " newValue) {\n";
+      ss << "      " << fixed_field_name << "PrivateField = newValue;\n";
+      ss << "    }\n";
+      ss << "  }\n";
+      return ss.str();
+    }
+    return "  property " + type_name + " " + fixed_field_name + ";\n";
+  }
+
+  std::string gen_store_function_begin(const std::string &storer_name, const std::string &class_name, int arity,
+                                       std::vector<var_description> &vars, int storer_type) const override {
+    if (storer_type < 0) {
+      return "";
+    }
+    std::stringstream ss;
+    ss << "\n";
+    if (storer_type) {
+      ss << (is_header_ ? "  virtual " : "") << "String^ " << (is_header_ ? "" : gen_class_name(class_name) + "::")
+         << "ToString()" << (is_header_ ? " override;" : " {\n  return ::Telegram::Td::Api::ToString(this);\n}") << "\n";
+    } else {
+      ss << (is_header_ ? "  virtual " : "") << "NativeObject^ "
+         << (is_header_ ? "" : gen_class_name(class_name) + "::") << "ToUnmanaged()";
+      if (is_header_) {
+        ss << ";\n";
+      } else {
+        ss << "{\n  return REF_NEW NativeObject(::Telegram::Td::Api::ToUnmanaged(this).release());\n}\n";
+      }
+    }
+    return ss.str();
+  }
+  std::string gen_store_function_end(const std::vector<var_description> &vars, int storer_type) const override {
+    return "";
+  }
+
+  std::string gen_constructor_begin(int fields_num, const std::string &class_name, bool is_default) const override {
+    std::stringstream ss;
+    ss << "\n";
+    ss << (is_header_ ? "  " : gen_class_name(class_name) + "::") << gen_class_name(class_name) << "(";
+    return ss.str();
+  }
+  std::string gen_constructor_parameter(int field_num, const std::string &class_name, const arg &a, bool is_default) const override {
+    if (is_default) {
+      return "";
+    }
+    std::stringstream ss;
+    ss << (field_num == 0 ? "" : ", ");
+    auto field_type = gen_field_type(a);
+    if (field_type.substr(0, 5) != "Array" && field_type.substr(0, 6) != "String" && to_upper(field_type[0]) == field_type[0]) {
+      field_type = "::Telegram::Td::Api::" + field_type;
+    }
+    ss << field_type << " " << to_camelCase(a.name);
+    return ss.str();
+  }
+  std::string gen_constructor_field_init(int field_num, const std::string &class_name, const arg &a, bool is_default) const override {
+    if (is_default || is_header_) {
+      return "";
+    }
+
+    std::stringstream ss;
+    if (field_num == 0) {
+      ss << ") {\n";
+    }
+    auto field_name = gen_field_name(a.name);
+    if (field_name == class_name) {
+      field_name += "Value";
+    }
+    ss << "  " << field_name << " = " << to_camelCase(a.name) << ";\n";
+
+    return ss.str();
+  }
+  std::string gen_constructor_end(const tl_combinator *t, int fields_num, bool is_default) const override {
+    if (is_header_) {
+      return ");\n";
+    }
+    std::stringstream ss;
+    if (fields_num == 0) {
+      ss << ") {\n";
+    }
+    ss << "}\n";
+    return ss.str();
+  }
+  std::string gen_additional_function(const std::string &function_name, const tl_combinator *t,
+                                      bool is_function) const override {
+    std::stringstream ss;
+    if (is_header_ && function_name == "ToUnmanaged") {
+      ss << "};\n";
+    }
+    ss << "\n";
+    if (function_name == "ToUnmanaged") {
+      gen_to_unmanaged(ss, t);
+    } else {
+      gen_from_unmanaged(ss, t);
+    }
+    return ss.str();
+  }
+  void gen_to_unmanaged(std::stringstream &ss, const tl_combinator *t) const {
+    auto native_class_name = gen_native_class_name(t->name);
+    auto class_name = gen_class_name(t->name);
+    ss << "td::td_api::object_ptr<td::td_api::" << native_class_name << "> ToUnmanaged(" << class_name
+       << "^ from)";
+    if (is_header_) {
+      ss << ";\n";
+      return;
+    }
+    ss << "{\n"
+       << "  if (!from) {\n"
+       << "    return nullptr;\n"
+       << "  }\n"
+       << "  return td::td_api::make_object<td::td_api::" << native_class_name << ">(";
+    bool is_first = true;
+    for (auto &it : t->args) {
+      if (is_first) {
+        is_first = false;
+      } else {
+        ss << ", ";
+      }
+      auto field_name = gen_field_name(it.name);
+      if (field_name == class_name) {
+        field_name += "Value";
+      }
+      ss << "ToUnmanaged(from->" << field_name << ")";
+    }
+    ss << ");\n}\n";
+  }
+
+  void gen_from_unmanaged(std::stringstream &ss, const tl_combinator *t) const {
+    auto native_class_name = gen_native_class_name(t->name);
+    auto class_name = gen_class_name(t->name);
+    ss << class_name << "^ FromUnmanaged(td::td_api::" << native_class_name << " &from)";
+    if (is_header_) {
+      ss << ";\n";
+      return;
+    }
+    ss << "{\n"
+       << "  return REF_NEW " << class_name << "(";
+    bool is_first = true;
+    for (auto &it : t->args) {
+      if (is_first) {
+        is_first = false;
+      } else {
+        ss << ", ";
+      }
+      ss << (gen_field_type(it) == "Array<byte>^" ? "Bytes" : "") << "FromUnmanaged(from." << gen_native_field_name(it.name) << ")";
+    }
+    ss << ");\n}\n";
+  }
+
+  std::string gen_array_type_name(const tl_tree_array *arr, const std::string &field_name) const override {
+    assert(0);
+    return std::string();
+  }
+  std::string gen_var_type_name(void) const override {
+    assert(0);
+    return std::string();
+  }
+
+  std::string gen_int_const(const tl_tree *tree_c, const std::vector<var_description> &vars) const override {
+    assert(0);
+    return std::string();
+  }
+
+  std::string gen_var_name(const var_description &desc) const override {
+    assert(0);
+    return "";
+  }
+  std::string gen_parameter_name(int index) const override {
+    assert(0);
+    return "";
+  }
+
+  std::string gen_class_alias(const std::string &class_name, const std::string &alias_name) const override {
+    return "";
+  }
+
+  std::string gen_vars(const tl_combinator *t, const tl_tree_type *result_type,
+                       std::vector<var_description> &vars) const override {
+    assert(vars.empty());
+    return "";
+  }
+  std::string gen_function_vars(const tl_combinator *t, std::vector<var_description> &vars) const override {
+    assert(vars.empty());
+    return "";
+  }
+  std::string gen_uni(const tl_tree_type *result_type, std::vector<var_description> &vars,
+                      bool check_negative) const override {
+    assert(result_type->children.empty());
+    return "";
+  }
+  std::string gen_constructor_id_store(std::int32_t id, int storer_type) const override {
+    return "";
+  }
+  std::string gen_field_fetch(int field_num, const arg &a, std::vector<var_description> &vars, bool flat,
+                              int parser_type) const override {
+    return "";
+    // std::stringstream ss;
+    // ss << gen_field_name(a.name) << " = from_unmanaged(from->" <<
+    // gen_native_field_name(a.name) << ");\n"; return ss.str();
+  }
+  std::string gen_field_store(const arg &a, std::vector<var_description> &vars, bool flat,
+                              int storer_type) const override {
+    return "";
+    // std::stringstream ss;
+    // ss << "to_unmanaged(" << gen_field_name(a.name) << ")";
+    // return ss.str();
+  }
+  std::string gen_type_fetch(const std::string &field_name, const tl_tree_type *tree_type,
+                             const std::vector<var_description> &vars, int parser_type) const override {
+    assert(vars.empty());
+    return "";
+  }
+
+  std::string gen_type_store(const std::string &field_name, const tl_tree_type *tree_type,
+                             const std::vector<var_description> &vars, int storer_type) const override {
+    return "";
+  }
+  std::string gen_var_type_fetch(const arg &a) const override {
+    assert(0);
+    return "";
+  }
+
+  std::string gen_get_id(const std::string &class_name, std::int32_t id, bool is_proxy) const override {
+    return "";
+  }
+
+  std::string gen_function_result_type(const tl_tree *result) const override {
+    return "";
+  }
+
+  std::string gen_fetch_function_begin(const std::string &parser_name, const std::string &class_name, int arity,
+                                       std::vector<var_description> &vars, int parser_type) const override {
+    return "";
+  }
+  std::string gen_fetch_function_end(int field_num, const std::vector<var_description> &vars,
+                                     int parser_type) const override {
+    return "";
+  }
+
+  std::string gen_fetch_function_result_begin(const std::string &parser_name, const std::string &class_name,
+                                              const tl_tree *result) const override {
+    return "";
+  }
+  std::string gen_fetch_function_result_end(void) const override {
+    return "";
+  }
+  std::string gen_fetch_function_result_any_begin(const std::string &parser_name, const std::string &class_name,
+                                                  bool is_proxy) const override {
+    return "";
+  }
+  std::string gen_fetch_function_result_any_end(bool is_proxy) const override {
+    return "";
+  }
+
+  std::string gen_fetch_switch_begin(void) const override {
+    return "";
+  }
+  std::string gen_fetch_switch_case(const tl_combinator *t, int arity) const override {
+    return "";
+  }
+  std::string gen_fetch_switch_end(void) const override {
+    return "";
+  }
+
+  std::string gen_additional_proxy_function_begin(const std::string &function_name, const tl_type *type,
+                                                  const std::string &name, int arity, bool is_function) const override {
+    std::stringstream ss;
+    if (is_header_ && function_name == "ToUnmanaged") {
+      ss << "};\n";
+    }
+    if (type == nullptr) {
+      return ss.str();
+    }
+    auto native_class_name = gen_native_class_name(type->name);
+    auto class_name = gen_class_name(type->name);
+    if (function_name == "ToUnmanaged") {
+      ss << "td::td_api::object_ptr<td::td_api::" << native_class_name << "> ToUnmanaged(" << class_name
+         << "^ from)";
+      if (is_header_) {
+        ss << ";\n";
+        return ss.str();
+      }
+      ss << "{\n"
+         << "  if (!from) {\n"
+         << "    return nullptr;\n"
+         << "  }\n"
+         << "  return td::td_api::move_object_as<td::td_api::" << native_class_name << ">(from->ToUnmanaged()->get_object_ptr());\n}\n";
+    } else {
+      ss << class_name << "^ FromUnmanaged(td::td_api::" << native_class_name << " &from)";
+      if (is_header_) {
+        ss << ";\n";
+        return ss.str();
+      }
+      ss << "{\n";
+      ss << "  CallFromUnmanaged<" << class_name << "^> res;\n";
+      ss << "  downcast_call(from, res);\n";
+      ss << "  return CallFromUnmanagedRes<" << class_name << "^>::res;\n";
+      ss << "}\n";
+    }
+    return ss.str();
+  }
+  std::string gen_additional_proxy_function_case(const std::string &function_name, const tl_type *type,
+                                                 const std::string &class_name, int arity) const override {
+    return "";
+  }
+  std::string gen_additional_proxy_function_case(const std::string &function_name, const tl_type *type,
+                                                 const tl_combinator *t, int arity, bool is_function) const override {
+    return "";
+  }
+  std::string gen_additional_proxy_function_end(const std::string &function_name, const tl_type *type,
+                                                bool is_function) const override {
+    return "";
+  }
+};
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_writer_h.cpp b/libs/tdlib/td/td/generate/tl_writer_h.cpp
new file mode 100644
index 0000000000..49eaf4982a
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_writer_h.cpp
@@ -0,0 +1,350 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_writer_h.h"
+
+#include <cassert>
+#include <utility>
+
+namespace td {
+
+std::string TD_TL_writer_h::forward_declaration(std::string type) {
+  std::string prefix;
+  std::string suffix;
+  do {
+    std::size_t pos = type.find("::");
+    if (pos == std::string::npos) {
+      return prefix + "class " + type + ";\n" + suffix;
+    }
+    std::string namespace_name = type.substr(0, pos);
+    type = type.substr(pos + 2);
+    prefix += "namespace " + namespace_name + " {\n";
+    suffix += "}  // namespace " + namespace_name + "\n";
+  } while (true);
+  assert(false);
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_output_begin() const {
+  std::string ext_include_str;
+  for (auto &it : ext_include) {
+    ext_include_str += "#include " + it + "\n";
+  }
+  if (!ext_include_str.empty()) {
+    ext_include_str += "\n";
+  }
+  std::string ext_forward_declaration;
+  for (auto &storer_name : get_storers()) {
+    ext_forward_declaration += forward_declaration(storer_name);
+  }
+  for (auto &parser_name : get_parsers()) {
+    ext_forward_declaration += forward_declaration(parser_name);
+  }
+  if (!ext_forward_declaration.empty()) {
+    ext_forward_declaration += "\n";
+  }
+  return "#pragma once\n\n"
+         "#include \"td/tl/TlObject.h\"\n\n" +
+         ext_include_str +
+         "#include <cstdint>\n"
+         "#include <memory>\n"
+         "#include <utility>\n"
+         "#include <vector>\n\n"
+         "namespace td {\n" +
+         ext_forward_declaration + "namespace " + tl_name +
+         " {\n\n"
+
+         "using BaseObject = ::td::TlObject;\n\n"
+
+         "template <class Type>\n"
+         "using object_ptr = ::td::tl_object_ptr<Type>;\n\n"
+         "template <class Type, class... Args>\n"
+         "object_ptr<Type> make_object(Args &&... args) {\n"
+         "  return object_ptr<Type>(new Type(std::forward<Args>(args)...));\n"
+         "}\n\n"
+
+         "template <class ToType, class FromType>\n"
+         "object_ptr<ToType> move_object_as(FromType &&from) {\n"
+         "  return object_ptr<ToType>(static_cast<ToType *>(from.release()));\n"
+         "}\n\n"
+
+         "std::string to_string(const BaseObject &value);\n\n"
+
+         "template <class T>\n"
+         "std::string to_string(const object_ptr<T> &value) {\n"
+         "  if (value == nullptr) {\n"
+         "    return \"null\";\n"
+         "  }\n"
+         "\n"
+         "  return to_string(*value);\n"
+         "}\n\n";
+}
+
+std::string TD_TL_writer_h::gen_output_end() const {
+  return "}  // namespace " + tl_name +
+         "\n"
+         "}  // namespace td\n";
+}
+
+std::string TD_TL_writer_h::gen_field_definition(const std::string &class_name, const std::string &type_name,
+                                                 const std::string &field_name) const {
+  return "  " + type_name + (type_name.empty() || type_name[type_name.size() - 1] == ' ' ? "" : " ") + field_name +
+         ";\n";
+}
+
+std::string TD_TL_writer_h::gen_vars(const tl::tl_combinator *t, const tl::tl_tree_type *result_type,
+                                     std::vector<tl::var_description> &vars) const {
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_function_vars(const tl::tl_combinator *t,
+                                              std::vector<tl::var_description> &vars) const {
+  for (std::size_t i = 0; i < vars.size(); i++) {
+    vars[i].index = static_cast<int>(i);
+    vars[i].is_stored = false;
+    vars[i].is_type = false;
+    vars[i].parameter_num = -1;
+    vars[i].function_arg_num = -1;
+  }
+
+  for (std::size_t i = 0; i < t->args.size(); i++) {
+    const tl::arg &a = t->args[i];
+
+    int arg_type = a.type->get_type();
+    if (arg_type == tl::NODE_TYPE_VAR_TYPE) {
+      const tl::tl_tree_var_type *var_type = static_cast<const tl::tl_tree_var_type *>(a.type);
+      assert(a.flags & tl::FLAG_EXCL);
+      assert(var_type->var_num >= 0);
+      assert(!vars[var_type->var_num].is_type);
+      vars[var_type->var_num].is_type = true;
+      vars[var_type->var_num].function_arg_num = static_cast<int>(i);
+    }
+  }
+
+  std::string res;
+  for (std::size_t i = 0; i < vars.size(); i++) {
+    if (!vars[i].is_type) {
+      assert(vars[i].parameter_num == -1);
+      assert(vars[i].function_arg_num == -1);
+      assert(vars[i].is_stored == false);
+      res += "  mutable " + gen_class_name("#") + " " + gen_var_name(vars[i]) + ";\n";
+    }
+  }
+  return res;
+}
+
+std::string TD_TL_writer_h::gen_flags_definitions(const tl::tl_combinator *t) const {
+  std::vector<std::pair<std::string, std::int32_t>> flags;
+
+  for (std::size_t i = 0; i < t->args.size(); i++) {
+    const tl::arg &a = t->args[i];
+
+    if (a.exist_var_num != -1) {
+      auto name = a.name;
+      for (auto &c : name) {
+        c = to_upper(c);
+      }
+      flags.push_back(std::make_pair(name, a.exist_var_bit));
+    }
+  }
+  std::string res;
+  if (!flags.empty()) {
+    res += "  enum Flags : std::int32_t {";
+    bool first = true;
+    for (auto &p : flags) {
+      if (first) {
+        first = false;
+      } else {
+        res += ", ";
+      }
+      res += p.first + "_MASK = " + int_to_string(1 << p.second);
+    }
+    res += "};\n";
+  }
+  return res;
+}
+
+std::string TD_TL_writer_h::gen_uni(const tl::tl_tree_type *result_type, std::vector<tl::var_description> &vars,
+                                    bool check_negative) const {
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_constructor_id_store(std::int32_t id, int storer_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_field_fetch(int field_num, const tl::arg &a, std::vector<tl::var_description> &vars,
+                                            bool flat, int parser_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_field_store(const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                                            int storer_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_type_fetch(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                                           const std::vector<tl::var_description> &vars, int parser_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_type_store(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                                           const std::vector<tl::var_description> &vars, int storer_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_var_type_fetch(const tl::arg &a) const {
+  assert(false);
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_forward_class_declaration(const std::string &class_name, bool is_proxy) const {
+  return "class " + class_name + ";\n\n";
+}
+
+std::string TD_TL_writer_h::gen_class_begin(const std::string &class_name, const std::string &base_class_name,
+                                            bool is_proxy) const {
+  return "class " + class_name + (!is_proxy ? " final " : "") + ": public " + base_class_name +
+         " {\n"
+         " public:\n";
+}
+
+std::string TD_TL_writer_h::gen_class_end() const {
+  return "};\n\n";
+}
+
+std::string TD_TL_writer_h::gen_class_alias(const std::string &class_name, const std::string &alias_name) const {
+  return "";
+  //  return "typedef " + class_name + " " + alias_name + ";\n\n\n";
+}
+
+std::string TD_TL_writer_h::gen_get_id(const std::string &class_name, std::int32_t id, bool is_proxy) const {
+  if (is_proxy) {
+    if (class_name == gen_base_tl_class_name()) {
+      return "\n  virtual std::int32_t get_id() const = 0;\n";
+    }
+
+    return "";
+  }
+
+  return "\n"
+         "  static const std::int32_t ID = " +
+         int_to_string(id) +
+         ";\n"
+         "  std::int32_t get_id() const final {\n"
+         "    return ID;\n"
+         "  }\n";
+}
+
+std::string TD_TL_writer_h::gen_function_result_type(const tl::tl_tree *result) const {
+  assert(result->get_type() == tl::NODE_TYPE_TYPE);
+  const tl::tl_tree_type *result_type = static_cast<const tl::tl_tree_type *>(result);
+  std::string fetched_type = gen_type_name(result_type);
+
+  if (!fetched_type.empty() && fetched_type[fetched_type.size() - 1] == ' ') {
+    fetched_type.pop_back();
+  }
+
+  return "\n"
+         "  using ReturnType = " +
+         fetched_type + ";\n";
+}
+
+std::string TD_TL_writer_h::gen_fetch_function_begin(const std::string &parser_name, const std::string &class_name,
+                                                     int arity, std::vector<tl::var_description> &vars,
+                                                     int parser_type) const {
+  std::string fetched_type = "object_ptr<" + class_name + "> ";
+
+  if (parser_type == 0) {
+    return "\n"
+           "  static " +
+           fetched_type + "fetch(" + parser_name +
+           " &p) {\n"
+           "    return make_tl_object<" +
+           class_name +
+           ">(p);\n"
+           "  }\n\n" +
+           "  explicit " + class_name + "(" + parser_name + " &p);\n";
+  }
+
+  assert(arity == 0);
+  return "\n"
+         "  static " +
+         fetched_type + "fetch(" + parser_name + " &p);\n";
+}
+
+std::string TD_TL_writer_h::gen_fetch_function_end(int field_num, const std::vector<tl::var_description> &vars,
+                                                   int parser_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_fetch_function_result_begin(const std::string &parser_name,
+                                                            const std::string &class_name,
+                                                            const tl::tl_tree *result) const {
+  return "\n"
+         "  static ReturnType fetch_result(" +
+         parser_name + " &p);\n";
+}
+
+std::string TD_TL_writer_h::gen_fetch_function_result_end() const {
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_fetch_function_result_any_begin(const std::string &parser_name,
+                                                                const std::string &class_name, bool is_proxy) const {
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_fetch_function_result_any_end(bool is_proxy) const {
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_store_function_begin(const std::string &storer_name, const std::string &class_name,
+                                                     int arity, std::vector<tl::var_description> &vars,
+                                                     int storer_type) const {
+  assert(arity == 0);
+  if (storer_type == -1) {
+    return "";
+  }
+  return "\n"
+         "  void store(" +
+         storer_name + " &s" + std::string(storer_type == 0 ? "" : ", const char *field_name") + ") const final;\n";
+}
+
+std::string TD_TL_writer_h::gen_store_function_end(const std::vector<tl::var_description> &vars,
+                                                   int storer_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_fetch_switch_begin() const {
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_fetch_switch_case(const tl::tl_combinator *t, int arity) const {
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_fetch_switch_end() const {
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_constructor_begin(int fields_num, const std::string &class_name,
+                                                  bool is_default) const {
+  return "\n"
+         "  " +
+         std::string(fields_num == 1 ? "explicit " : "") + class_name + "(";
+}
+
+std::string TD_TL_writer_h::gen_constructor_field_init(int field_num, const std::string &class_name, const tl::arg &a,
+                                                       bool is_default) const {
+  return "";
+}
+
+std::string TD_TL_writer_h::gen_constructor_end(const tl::tl_combinator *t, int fields_num, bool is_default) const {
+  return ");\n";
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_writer_h.h b/libs/tdlib/td/td/generate/tl_writer_h.h
new file mode 100644
index 0000000000..e763ea47e3
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_writer_h.h
@@ -0,0 +1,91 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "tl_writer_td.h"
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+namespace td {
+
+class TD_TL_writer_h : public TD_TL_writer {
+ protected:
+  const std::vector<std::string> ext_include;
+
+  static std::string forward_declaration(std::string type);
+
+ public:
+  TD_TL_writer_h(const std::string &tl_name, const std::string &string_type, const std::string &bytes_type,
+                 const std::vector<std::string> &ext_include)
+      : TD_TL_writer(tl_name, string_type, bytes_type), ext_include(ext_include) {
+  }
+
+  std::string gen_output_begin() const override;
+  std::string gen_output_end() const override;
+
+  std::string gen_forward_class_declaration(const std::string &class_name, bool is_proxy) const override;
+
+  std::string gen_class_begin(const std::string &class_name, const std::string &base_class_name,
+                              bool is_proxy) const override;
+  std::string gen_class_end() const override;
+
+  std::string gen_class_alias(const std::string &class_name, const std::string &alias_name) const override;
+
+  std::string gen_field_definition(const std::string &class_name, const std::string &type_name,
+                                   const std::string &field_name) const override;
+
+  std::string gen_flags_definitions(const tl::tl_combinator *t) const override;
+  std::string gen_vars(const tl::tl_combinator *t, const tl::tl_tree_type *result_type,
+                       std::vector<tl::var_description> &vars) const override;
+  std::string gen_function_vars(const tl::tl_combinator *t, std::vector<tl::var_description> &vars) const override;
+  std::string gen_uni(const tl::tl_tree_type *result_type, std::vector<tl::var_description> &vars,
+                      bool check_negative) const override;
+  std::string gen_constructor_id_store(std::int32_t id, int storer_type) const override;
+
+  std::string gen_field_fetch(int field_num, const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                              int parser_type) const override;
+  std::string gen_field_store(const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                              int storer_type) const override;
+  std::string gen_type_fetch(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                             const std::vector<tl::var_description> &vars, int parser_type) const override;
+  std::string gen_type_store(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                             const std::vector<tl::var_description> &vars, int storer_type) const override;
+  std::string gen_var_type_fetch(const tl::arg &a) const override;
+
+  std::string gen_get_id(const std::string &class_name, std::int32_t id, bool is_proxy) const override;
+
+  std::string gen_function_result_type(const tl::tl_tree *result) const override;
+
+  std::string gen_fetch_function_begin(const std::string &parser_name, const std::string &class_name, int arity,
+                                       std::vector<tl::var_description> &vars, int parser_type) const override;
+  std::string gen_fetch_function_end(int field_num, const std::vector<tl::var_description> &vars,
+                                     int parser_type) const override;
+
+  std::string gen_fetch_function_result_begin(const std::string &parser_name, const std::string &class_name,
+                                              const tl::tl_tree *result) const override;
+  std::string gen_fetch_function_result_end() const override;
+  std::string gen_fetch_function_result_any_begin(const std::string &parser_name, const std::string &class_name,
+                                                  bool is_proxy) const override;
+  std::string gen_fetch_function_result_any_end(bool is_proxy) const override;
+
+  std::string gen_store_function_begin(const std::string &storer_name, const std::string &class_name, int arity,
+                                       std::vector<tl::var_description> &vars, int storer_type) const override;
+  std::string gen_store_function_end(const std::vector<tl::var_description> &vars, int storer_type) const override;
+
+  std::string gen_fetch_switch_begin() const override;
+  std::string gen_fetch_switch_case(const tl::tl_combinator *t, int arity) const override;
+  std::string gen_fetch_switch_end() const override;
+
+  std::string gen_constructor_begin(int fields_num, const std::string &class_name, bool is_default) const override;
+  std::string gen_constructor_field_init(int field_num, const std::string &class_name, const tl::arg &a,
+                                         bool is_default) const override;
+  std::string gen_constructor_end(const tl::tl_combinator *t, int fields_num, bool is_default) const override;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_writer_hpp.cpp b/libs/tdlib/td/td/generate/tl_writer_hpp.cpp
new file mode 100644
index 0000000000..56e8e31ea0
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_writer_hpp.cpp
@@ -0,0 +1,268 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_writer_hpp.h"
+
+#include <cassert>
+
+namespace td {
+
+bool TD_TL_writer_hpp::is_documentation_generated() const {
+#ifdef DISABLE_HPP_DOCUMENTATION
+  return false;
+#else
+  return true;
+#endif
+}
+
+int TD_TL_writer_hpp::get_additional_function_type(const std::string &additional_function_name) const {
+  assert(additional_function_name == "downcast_call");
+  return 2;
+}
+
+std::vector<std::string> TD_TL_writer_hpp::get_additional_functions() const {
+  std::vector<std::string> additional_functions;
+  additional_functions.push_back("downcast_call");
+  return additional_functions;
+}
+
+std::string TD_TL_writer_hpp::gen_base_type_class_name(int arity) const {
+  assert(arity == 0);
+  return "Object";
+}
+
+std::string TD_TL_writer_hpp::gen_base_tl_class_name() const {
+  return "BaseObject";
+}
+
+std::string TD_TL_writer_hpp::gen_output_begin() const {
+  return "#pragma once\n"
+         "\n"
+#ifndef DISABLE_HPP_DOCUMENTATION
+         "/**\n"
+         " * \\file\n"
+         " * Contains downcast_call methods for calling a function object on downcasted to\n"
+         " * the most derived class TDLib API object.\n"
+         " */\n"
+#endif
+         "#include \"" +
+         tl_name +
+         ".h\"\n"
+         "\n"
+         "namespace td {\n"
+         "namespace " +
+         tl_name + " {\n\n";
+}
+
+std::string TD_TL_writer_hpp::gen_output_end() const {
+  return "}  // namespace " + tl_name +
+         "\n"
+         "}  // namespace td\n";
+}
+
+std::string TD_TL_writer_hpp::gen_field_definition(const std::string &class_name, const std::string &type_name,
+                                                   const std::string &field_name) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_vars(const tl::tl_combinator *t, const tl::tl_tree_type *result_type,
+                                       std::vector<tl::var_description> &vars) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_function_vars(const tl::tl_combinator *t,
+                                                std::vector<tl::var_description> &vars) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_uni(const tl::tl_tree_type *result_type, std::vector<tl::var_description> &vars,
+                                      bool check_negative) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_constructor_id_store(std::int32_t id, int storer_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_field_fetch(int field_num, const tl::arg &a, std::vector<tl::var_description> &vars,
+                                              bool flat, int parser_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_field_store(const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                                              int storer_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_type_fetch(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                                             const std::vector<tl::var_description> &vars, int parser_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_type_store(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                                             const std::vector<tl::var_description> &vars, int storer_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_var_type_fetch(const tl::arg &a) const {
+  assert(false);
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_forward_class_declaration(const std::string &class_name, bool is_proxy) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_class_begin(const std::string &class_name, const std::string &base_class_name,
+                                              bool is_proxy) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_class_end() const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_class_alias(const std::string &class_name, const std::string &alias_name) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_get_id(const std::string &class_name, std::int32_t id, bool is_proxy) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_function_result_type(const tl::tl_tree *result) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_fetch_function_begin(const std::string &parser_name, const std::string &class_name,
+                                                       int arity, std::vector<tl::var_description> &vars,
+                                                       int parser_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_fetch_function_end(int field_num, const std::vector<tl::var_description> &vars,
+                                                     int parser_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_fetch_function_result_begin(const std::string &parser_name,
+                                                              const std::string &class_name,
+                                                              const tl::tl_tree *result) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_fetch_function_result_end() const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_fetch_function_result_any_begin(const std::string &parser_name,
+                                                                  const std::string &class_name, bool is_proxy) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_fetch_function_result_any_end(bool is_proxy) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_store_function_begin(const std::string &storer_name, const std::string &class_name,
+                                                       int arity, std::vector<tl::var_description> &vars,
+                                                       int storer_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_store_function_end(const std::vector<tl::var_description> &vars,
+                                                     int storer_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_fetch_switch_begin() const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_fetch_switch_case(const tl::tl_combinator *t, int arity) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_fetch_switch_end() const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_additional_function(const std::string &function_name, const tl::tl_combinator *t,
+                                                      bool is_function) const {
+  assert(function_name == "downcast_call");
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_additional_proxy_function_begin(const std::string &function_name,
+                                                                  const tl::tl_type *type,
+                                                                  const std::string &class_name, int arity,
+                                                                  bool is_function) const {
+  assert(function_name == "downcast_call");
+  return
+#ifndef DISABLE_HPP_DOCUMENTATION
+      "/**\n"
+      " * Calls the specified function object with the given object downcasted to its most derived type.\n"
+      " * \\param[in] obj Object to pass as an argument to the function object.\n"
+      " * \\param[in] func Function object to which the object will be passed.\n"
+      " * \\returns Whether function object call has happened. Should always return true for correct parameters.\n"
+      " */\n"
+#endif
+      "template <class T>\n"
+      "bool downcast_call(" +
+      class_name +
+      " &obj, const T &func) {\n"
+      "  switch (obj.get_id()) {\n";
+}
+
+std::string TD_TL_writer_hpp::gen_additional_proxy_function_case(const std::string &function_name,
+                                                                 const tl::tl_type *type, const std::string &class_name,
+                                                                 int arity) const {
+  assert(function_name == "downcast_call");
+  assert(false);
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_additional_proxy_function_case(const std::string &function_name,
+                                                                 const tl::tl_type *type, const tl::tl_combinator *t,
+                                                                 int arity, bool is_function) const {
+  assert(function_name == "downcast_call");
+  return "    case " + gen_class_name(t->name) +
+         "::ID:\n"
+         "      func(static_cast<" +
+         gen_class_name(t->name) +
+         " &>(obj));\n"
+         "      return true;\n";
+}
+
+std::string TD_TL_writer_hpp::gen_additional_proxy_function_end(const std::string &function_name,
+                                                                const tl::tl_type *type, bool is_function) const {
+  assert(function_name == "downcast_call");
+  return "    default:\n"
+         "      return false;\n"
+         "  }\n"
+         "}\n\n";
+}
+
+std::string TD_TL_writer_hpp::gen_constructor_begin(int fields_num, const std::string &class_name,
+                                                    bool is_default) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_constructor_parameter(int field_num, const std::string &class_name, const tl::arg &a,
+                                                        bool is_default) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_constructor_field_init(int field_num, const std::string &class_name, const tl::arg &a,
+                                                         bool is_default) const {
+  return "";
+}
+
+std::string TD_TL_writer_hpp::gen_constructor_end(const tl::tl_combinator *t, int fields_num, bool is_default) const {
+  return "";
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_writer_hpp.h b/libs/tdlib/td/td/generate/tl_writer_hpp.h
new file mode 100644
index 0000000000..119fa87a5c
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_writer_hpp.h
@@ -0,0 +1,107 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "tl_writer_td.h"
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+namespace td {
+
+class TD_TL_writer_hpp : public TD_TL_writer {
+ public:
+  TD_TL_writer_hpp(const std::string &tl_name, const std::string &string_type, const std::string &bytes_type)
+      : TD_TL_writer(tl_name, string_type, bytes_type) {
+  }
+
+  bool is_documentation_generated() const override;
+
+  int get_additional_function_type(const std::string &additional_function_name) const override;
+  std::vector<std::string> get_additional_functions() const override;
+
+  std::string gen_base_type_class_name(int arity) const override;
+  std::string gen_base_tl_class_name() const override;
+
+  std::string gen_output_begin() const override;
+  std::string gen_output_end() const override;
+
+  std::string gen_forward_class_declaration(const std::string &class_name, bool is_proxy) const override;
+
+  std::string gen_class_begin(const std::string &class_name, const std::string &base_class_name,
+                              bool is_proxy) const override;
+  std::string gen_class_end() const override;
+
+  std::string gen_class_alias(const std::string &class_name, const std::string &alias_name) const override;
+
+  std::string gen_field_definition(const std::string &class_name, const std::string &type_name,
+                                   const std::string &field_name) const override;
+
+  std::string gen_vars(const tl::tl_combinator *t, const tl::tl_tree_type *result_type,
+                       std::vector<tl::var_description> &vars) const override;
+  std::string gen_function_vars(const tl::tl_combinator *t, std::vector<tl::var_description> &vars) const override;
+  std::string gen_uni(const tl::tl_tree_type *result_type, std::vector<tl::var_description> &vars,
+                      bool check_negative) const override;
+  std::string gen_constructor_id_store(std::int32_t id, int storer_type) const override;
+
+  std::string gen_field_fetch(int field_num, const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                              int parser_type) const override;
+  std::string gen_field_store(const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                              int storer_type) const override;
+  std::string gen_type_fetch(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                             const std::vector<tl::var_description> &vars, int parser_type) const override;
+  std::string gen_type_store(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                             const std::vector<tl::var_description> &vars, int storer_type) const override;
+  std::string gen_var_type_fetch(const tl::arg &a) const override;
+
+  std::string gen_get_id(const std::string &class_name, std::int32_t id, bool is_proxy) const override;
+
+  std::string gen_function_result_type(const tl::tl_tree *result) const override;
+
+  std::string gen_fetch_function_begin(const std::string &parser_name, const std::string &class_name, int arity,
+                                       std::vector<tl::var_description> &vars, int parser_type) const override;
+  std::string gen_fetch_function_end(int field_num, const std::vector<tl::var_description> &vars,
+                                     int parser_type) const override;
+
+  std::string gen_fetch_function_result_begin(const std::string &parser_name, const std::string &class_name,
+                                              const tl::tl_tree *result) const override;
+  std::string gen_fetch_function_result_end() const override;
+  std::string gen_fetch_function_result_any_begin(const std::string &parser_name, const std::string &class_name,
+                                                  bool is_proxy) const override;
+  std::string gen_fetch_function_result_any_end(bool is_proxy) const override;
+
+  std::string gen_store_function_begin(const std::string &storer_name, const std::string &class_name, int arity,
+                                       std::vector<tl::var_description> &vars, int storer_type) const override;
+  std::string gen_store_function_end(const std::vector<tl::var_description> &vars, int storer_type) const override;
+
+  std::string gen_fetch_switch_begin() const override;
+  std::string gen_fetch_switch_case(const tl::tl_combinator *t, int arity) const override;
+  std::string gen_fetch_switch_end() const override;
+
+  std::string gen_constructor_begin(int fields_num, const std::string &class_name, bool is_default) const override;
+  std::string gen_constructor_parameter(int field_num, const std::string &class_name, const tl::arg &a,
+                                        bool is_default) const override;
+  std::string gen_constructor_field_init(int field_num, const std::string &class_name, const tl::arg &a,
+                                         bool is_default) const override;
+  std::string gen_constructor_end(const tl::tl_combinator *t, int fields_num, bool is_default) const override;
+
+  std::string gen_additional_function(const std::string &function_name, const tl::tl_combinator *t,
+                                      bool is_function) const override;
+  std::string gen_additional_proxy_function_begin(const std::string &function_name, const tl::tl_type *type,
+                                                  const std::string &class_name, int arity,
+                                                  bool is_function) const override;
+  std::string gen_additional_proxy_function_case(const std::string &function_name, const tl::tl_type *type,
+                                                 const std::string &class_name, int arity) const override;
+  std::string gen_additional_proxy_function_case(const std::string &function_name, const tl::tl_type *type,
+                                                 const tl::tl_combinator *t, int arity,
+                                                 bool is_function) const override;
+  std::string gen_additional_proxy_function_end(const std::string &function_name, const tl::tl_type *type,
+                                                bool is_function) const override;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_writer_java.cpp b/libs/tdlib/td/td/generate/tl_writer_java.cpp
new file mode 100644
index 0000000000..e243384eae
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_writer_java.cpp
@@ -0,0 +1,454 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_writer_java.h"
+
+#include <cassert>
+
+namespace td {
+
+const int TD_TL_writer_java::MAX_ARITY;
+
+const std::string TD_TL_writer_java::base_type_class_names[MAX_ARITY + 1] = {"Object"};
+const std::string TD_TL_writer_java::base_tl_class_name = "Object";
+const std::string TD_TL_writer_java::base_function_class_name = "Function";
+
+int TD_TL_writer_java::get_max_arity() const {
+  return MAX_ARITY;
+}
+
+bool TD_TL_writer_java::is_built_in_simple_type(const std::string &name) const {
+  return name == "Bool" || name == "Int32" || name == "Int53" || name == "Int64" || name == "Double" ||
+         name == "String" || name == "Bytes";
+}
+
+bool TD_TL_writer_java::is_built_in_complex_type(const std::string &name) const {
+  return name == "Vector";
+}
+
+bool TD_TL_writer_java::is_type_bare(const tl::tl_type *t) const {
+  return t->simple_constructors == 1 || (is_built_in_simple_type(t->name) && t->name != "Bool") ||
+         is_built_in_complex_type(t->name);
+}
+
+bool TD_TL_writer_java::is_combinator_supported(const tl::tl_combinator *constructor) const {
+  if (!TL_writer::is_combinator_supported(constructor)) {
+    return false;
+  }
+
+  for (std::size_t i = 0; i < constructor->args.size(); i++) {
+    if (constructor->args[i].type->get_type() == tl::NODE_TYPE_VAR_TYPE) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+int TD_TL_writer_java::get_parser_type(const tl::tl_combinator *t, const std::string &parser_name) const {
+  return 0;
+}
+
+int TD_TL_writer_java::get_storer_type(const tl::tl_combinator *t, const std::string &storer_name) const {
+  return 0;
+}
+
+std::vector<std::string> TD_TL_writer_java::get_parsers() const {
+  std::vector<std::string> parsers;
+  parsers.push_back("<inlined>");
+  return parsers;
+}
+
+std::vector<std::string> TD_TL_writer_java::get_storers() const {
+  return std::vector<std::string>();
+}
+
+std::string TD_TL_writer_java::gen_base_tl_class_name() const {
+  return base_tl_class_name;
+}
+
+std::string TD_TL_writer_java::gen_base_type_class_name(int arity) const {
+  assert(arity == 0);
+  return base_type_class_names[arity];
+}
+
+std::string TD_TL_writer_java::gen_base_function_class_name() const {
+  return base_function_class_name;
+}
+
+std::string TD_TL_writer_java::gen_class_name(std::string name) const {
+  if (name == "Object" || name == "#") {
+    assert(false);
+  }
+  bool next_to_upper = true;
+  std::string result;
+  for (std::size_t i = 0; i < name.size(); i++) {
+    if (!is_alnum(name[i])) {
+      next_to_upper = true;
+      continue;
+    }
+    if (next_to_upper) {
+      result += to_upper(name[i]);
+      next_to_upper = false;
+    } else {
+      result += name[i];
+    }
+  }
+  return result;
+}
+
+std::string TD_TL_writer_java::gen_field_name(std::string name) const {
+  assert(name.size() > 0);
+  assert(is_alnum(name.back()));
+
+  bool next_to_upper = false;
+  std::string result;
+  for (std::size_t i = 0; i < name.size(); i++) {
+    if (!is_alnum(name[i])) {
+      next_to_upper = true;
+      continue;
+    }
+    if (next_to_upper) {
+      result += to_upper(name[i]);
+      next_to_upper = false;
+    } else {
+      result += name[i];
+    }
+  }
+  return result;
+}
+
+std::string TD_TL_writer_java::gen_var_name(const tl::var_description &desc) const {
+  assert(false);
+  return std::string();
+}
+
+std::string TD_TL_writer_java::gen_parameter_name(int index) const {
+  assert(false);
+  return std::string();
+}
+
+std::string TD_TL_writer_java::gen_type_name(const tl::tl_tree_type *tree_type) const {
+  const tl::tl_type *t = tree_type->type;
+  const std::string &name = t->name;
+
+  if (name == "#") {
+    assert(false);
+  }
+  if (name == "Bool") {
+    return "boolean";
+  }
+  if (name == "Int32") {
+    return "int";
+  }
+  if (name == "Int53" || name == "Int64") {
+    return "long";
+  }
+  if (name == "Double") {
+    return "double";
+  }
+  if (name == "String") {
+    return "String";
+  }
+  if (name == "Bytes") {
+    return "byte[]";
+  }
+
+  if (name == "Vector") {
+    assert(t->arity == 1);
+    assert(tree_type->children.size() == 1);
+    assert(tree_type->children[0]->get_type() == tl::NODE_TYPE_TYPE);
+    const tl::tl_tree_type *child = static_cast<const tl::tl_tree_type *>(tree_type->children[0]);
+
+    return gen_type_name(child) + "[]";
+  }
+
+  assert(!is_built_in_simple_type(name) && !is_built_in_complex_type(name));
+
+  for (std::size_t i = 0; i < tree_type->children.size(); i++) {
+    assert(tree_type->children[i]->get_type() == tl::NODE_TYPE_NAT_CONST);
+  }
+
+  return gen_main_class_name(t);
+}
+
+std::string TD_TL_writer_java::gen_array_type_name(const tl::tl_tree_array *arr, const std::string &field_name) const {
+  assert(false);
+  return std::string();
+}
+
+std::string TD_TL_writer_java::gen_var_type_name() const {
+  return gen_base_function_class_name();
+}
+
+std::string TD_TL_writer_java::gen_int_const(const tl::tl_tree *tree_c,
+                                             const std::vector<tl::var_description> &vars) const {
+  assert(false);
+  return std::string();
+}
+
+std::string TD_TL_writer_java::gen_output_begin() const {
+  return "package " + package_name +
+         ";\n\n"
+         "public class " +
+         tl_name + " {\n";
+}
+
+std::string TD_TL_writer_java::gen_output_end() const {
+  return "}\n";
+}
+
+std::string TD_TL_writer_java::gen_forward_class_declaration(const std::string &class_name, bool is_proxy) const {
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_class_begin(const std::string &class_name, const std::string &base_class_name,
+                                               bool is_proxy) const {
+  std::string full_class_name = "static class " + class_name;
+  if (class_name != gen_base_tl_class_name()) {
+    full_class_name += " extends " + base_class_name;
+  }
+  std::string result = "    public " + std::string(is_proxy ? "abstract " : "") + full_class_name + " {\n";
+  if (class_name == gen_base_tl_class_name() || class_name == gen_base_function_class_name()) {
+    result += "        public native String toString();\n";
+  }
+
+  return result;
+}
+
+std::string TD_TL_writer_java::gen_class_end() const {
+  return "    }\n\n";
+}
+
+std::string TD_TL_writer_java::gen_class_alias(const std::string &class_name, const std::string &alias_name) const {
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_field_definition(const std::string &class_name, const std::string &type_name,
+                                                    const std::string &field_name) const {
+  return "        public " + type_name + " " + field_name + ";\n";
+}
+
+std::string TD_TL_writer_java::gen_vars(const tl::tl_combinator *t, const tl::tl_tree_type *result_type,
+                                        std::vector<tl::var_description> &vars) const {
+  for (std::size_t i = 0; i < vars.size(); i++) {
+    vars[i].index = static_cast<int>(i);
+    vars[i].is_stored = false;
+    vars[i].is_type = false;
+    vars[i].parameter_num = -1;
+    vars[i].function_arg_num = -1;
+  }
+
+  if (result_type != nullptr) {
+    assert(result_type->children.empty());
+  }
+
+  for (std::size_t i = 0; i < t->args.size(); i++) {
+    assert(t->args[i].type->get_type() != tl::NODE_TYPE_VAR_TYPE);
+  }
+
+  for (std::size_t i = 0; i < vars.size(); i++) {
+    assert(vars[i].is_type);
+  }
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_function_vars(const tl::tl_combinator *t,
+                                                 std::vector<tl::var_description> &vars) const {
+  for (std::size_t i = 0; i < vars.size(); i++) {
+    vars[i].index = static_cast<int>(i);
+    vars[i].is_stored = false;
+    vars[i].is_type = false;
+    vars[i].parameter_num = -1;
+    vars[i].function_arg_num = -1;
+  }
+
+  for (std::size_t i = 0; i < t->args.size(); i++) {
+    assert(t->args[i].type->get_type() != tl::NODE_TYPE_VAR_TYPE);
+  }
+
+  for (std::size_t i = 0; i < vars.size(); i++) {
+    assert(vars[i].is_type);
+  }
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_uni(const tl::tl_tree_type *result_type, std::vector<tl::var_description> &vars,
+                                       bool check_negative) const {
+  assert(result_type->children.empty());
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_constructor_id_store(std::int32_t id, int storer_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_field_fetch(int field_num, const tl::arg &a, std::vector<tl::var_description> &vars,
+                                               bool flat, int parser_type) const {
+  assert(parser_type >= 0);
+
+  assert(a.exist_var_num == -1);
+  assert(a.type->get_type() != tl::NODE_TYPE_VAR_TYPE);
+
+  assert(!(a.flags & tl::FLAG_EXCL));
+  assert(!(a.flags & tl::FLAG_OPT_VAR));
+
+  if (flat) {
+    //    TODO
+    //    return gen_field_fetch(const tl::arg &a, std::vector<tl::var_description> &vars, int num, bool flat);
+  }
+
+  assert(a.var_num == -1);
+  assert(a.type->get_type() == tl::NODE_TYPE_TYPE);
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_field_store(const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                                               int storer_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_type_fetch(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                                              const std::vector<tl::var_description> &vars, int parser_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_type_store(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                                              const std::vector<tl::var_description> &vars, int storer_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_var_type_fetch(const tl::arg &a) const {
+  assert(false);
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_get_id(const std::string &class_name, std::int32_t id, bool is_proxy) const {
+  if (is_proxy) {
+    return class_name == gen_base_tl_class_name() ? "\n        public abstract int getConstructor();\n" : "";
+  }
+
+  return "\n"
+         "        public static final int CONSTRUCTOR = " +
+         int_to_string(id) +
+         ";\n\n"
+         "        @Override\n"
+         "        public int getConstructor() {\n"
+         "            return " +
+         int_to_string(id) +
+         ";\n"
+         "        }\n";
+}
+
+std::string TD_TL_writer_java::gen_function_result_type(const tl::tl_tree *result) const {
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_fetch_function_begin(const std::string &parser_name, const std::string &class_name,
+                                                        int arity, std::vector<tl::var_description> &vars,
+                                                        int parser_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_fetch_function_end(int field_num, const std::vector<tl::var_description> &vars,
+                                                      int parser_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_fetch_function_result_begin(const std::string &parser_name,
+                                                               const std::string &class_name,
+                                                               const tl::tl_tree *result) const {
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_fetch_function_result_end() const {
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_fetch_function_result_any_begin(const std::string &parser_name,
+                                                                   const std::string &class_name, bool is_proxy) const {
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_fetch_function_result_any_end(bool is_proxy) const {
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_store_function_begin(const std::string &storer_name, const std::string &class_name,
+                                                        int arity, std::vector<tl::var_description> &vars,
+                                                        int storer_type) const {
+  assert(false);
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_store_function_end(const std::vector<tl::var_description> &vars,
+                                                      int storer_type) const {
+  assert(false);
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_fetch_switch_begin() const {
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_fetch_switch_case(const tl::tl_combinator *t, int arity) const {
+  assert(arity == 0);
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_fetch_switch_end() const {
+  return "";
+}
+
+std::string TD_TL_writer_java::gen_constructor_begin(int fields_num, const std::string &class_name,
+                                                     bool is_default) const {
+  return "\n"
+         "        public " +
+         class_name + "(";
+}
+
+std::string TD_TL_writer_java::gen_constructor_parameter(int field_num, const std::string &class_name, const tl::arg &a,
+                                                         bool is_default) const {
+  if (is_default) {
+    return "";
+  }
+
+  std::string field_type = gen_field_type(a);
+  if (field_type.empty()) {
+    return "";
+  }
+
+  if (field_type[field_type.size() - 1] != ' ') {
+    field_type += ' ';
+  }
+
+  return (field_num == 0 ? "" : ", ") + field_type + gen_field_name(a.name);
+}
+
+std::string TD_TL_writer_java::gen_constructor_field_init(int field_num, const std::string &class_name,
+                                                          const tl::arg &a, bool is_default) const {
+  std::string field_type = gen_field_type(a);
+  if (field_type.empty()) {
+    return "";
+  }
+
+  if (is_default) {
+    return (field_num == 0 ? ") {\n" : "");
+  }
+
+  return std::string(field_num == 0 ? ") {\n" : "") + "            this." + gen_field_name(a.name) + " = " +
+         gen_field_name(a.name) + ";\n";
+}
+
+std::string TD_TL_writer_java::gen_constructor_end(const tl::tl_combinator *t, int fields_num, bool is_default) const {
+  if (fields_num == 0) {
+    return ") {\n"
+           "        }\n";
+  }
+  return "        }\n";
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_writer_java.h b/libs/tdlib/td/td/generate/tl_writer_java.h
new file mode 100644
index 0000000000..cb8a161f02
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_writer_java.h
@@ -0,0 +1,118 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/tl/tl_writer.h"
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+namespace td {
+
+class TD_TL_writer_java : public tl::TL_writer {
+  static const int MAX_ARITY = 0;
+
+  static const std::string base_type_class_names[MAX_ARITY + 1];
+  static const std::string base_tl_class_name;
+  static const std::string base_function_class_name;
+
+  const std::string package_name;
+
+ public:
+  TD_TL_writer_java(const std::string &tl_name, const std::string &package_name)
+      : TL_writer(tl_name), package_name(package_name) {
+  }
+
+  int get_max_arity() const override;
+
+  bool is_built_in_simple_type(const std::string &name) const override;
+  bool is_built_in_complex_type(const std::string &name) const override;
+  bool is_type_bare(const tl::tl_type *t) const override;
+  bool is_combinator_supported(const tl::tl_combinator *constructor) const override;
+
+  int get_parser_type(const tl::tl_combinator *t, const std::string &parser_name) const override;
+  int get_storer_type(const tl::tl_combinator *t, const std::string &storer_name) const override;
+  std::vector<std::string> get_parsers() const override;
+  std::vector<std::string> get_storers() const override;
+
+  std::string gen_base_tl_class_name() const override;
+  std::string gen_base_type_class_name(int arity) const override;
+  std::string gen_base_function_class_name() const override;
+  std::string gen_class_name(std::string name) const override;
+  std::string gen_field_name(std::string name) const override;
+  std::string gen_var_name(const tl::var_description &desc) const override;
+  std::string gen_parameter_name(int index) const override;
+  std::string gen_type_name(const tl::tl_tree_type *tree_type) const override;
+  std::string gen_array_type_name(const tl::tl_tree_array *arr, const std::string &field_name) const override;
+  std::string gen_var_type_name() const override;
+
+  std::string gen_int_const(const tl::tl_tree *tree_c, const std::vector<tl::var_description> &vars) const override;
+
+  std::string gen_output_begin() const override;
+  std::string gen_output_end() const override;
+
+  std::string gen_forward_class_declaration(const std::string &class_name, bool is_proxy) const override;
+
+  std::string gen_class_begin(const std::string &class_name, const std::string &base_class_name,
+                              bool is_proxy) const override;
+  std::string gen_class_end() const override;
+
+  std::string gen_class_alias(const std::string &class_name, const std::string &alias_name) const override;
+
+  std::string gen_field_definition(const std::string &class_name, const std::string &type_name,
+                                   const std::string &field_name) const override;
+
+  std::string gen_vars(const tl::tl_combinator *t, const tl::tl_tree_type *result_type,
+                       std::vector<tl::var_description> &vars) const override;
+  std::string gen_function_vars(const tl::tl_combinator *t, std::vector<tl::var_description> &vars) const override;
+  std::string gen_uni(const tl::tl_tree_type *result_type, std::vector<tl::var_description> &vars,
+                      bool check_negative) const override;
+  std::string gen_constructor_id_store(std::int32_t id, int storer_type) const override;
+  std::string gen_field_fetch(int field_num, const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                              int parser_type) const override;
+  std::string gen_field_store(const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                              int storer_type) const override;
+  std::string gen_type_fetch(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                             const std::vector<tl::var_description> &vars, int parser_type) const override;
+  std::string gen_type_store(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                             const std::vector<tl::var_description> &vars, int storer_type) const override;
+  std::string gen_var_type_fetch(const tl::arg &a) const override;
+
+  std::string gen_get_id(const std::string &class_name, std::int32_t id, bool is_proxy) const override;
+
+  std::string gen_function_result_type(const tl::tl_tree *result) const override;
+
+  std::string gen_fetch_function_begin(const std::string &parser_name, const std::string &class_name, int arity,
+                                       std::vector<tl::var_description> &vars, int parser_type) const override;
+  std::string gen_fetch_function_end(int field_num, const std::vector<tl::var_description> &vars,
+                                     int parser_type) const override;
+
+  std::string gen_fetch_function_result_begin(const std::string &parser_name, const std::string &class_name,
+                                              const tl::tl_tree *result) const override;
+  std::string gen_fetch_function_result_end() const override;
+  std::string gen_fetch_function_result_any_begin(const std::string &parser_name, const std::string &class_name,
+                                                  bool is_proxy) const override;
+  std::string gen_fetch_function_result_any_end(bool is_proxy) const override;
+
+  std::string gen_store_function_begin(const std::string &storer_name, const std::string &class_name, int arity,
+                                       std::vector<tl::var_description> &vars, int storer_type) const override;
+  std::string gen_store_function_end(const std::vector<tl::var_description> &vars, int storer_type) const override;
+
+  std::string gen_fetch_switch_begin() const override;
+  std::string gen_fetch_switch_case(const tl::tl_combinator *t, int arity) const override;
+  std::string gen_fetch_switch_end() const override;
+
+  std::string gen_constructor_begin(int fields_num, const std::string &class_name, bool is_default) const override;
+  std::string gen_constructor_parameter(int field_num, const std::string &class_name, const tl::arg &a,
+                                        bool is_default) const override;
+  std::string gen_constructor_field_init(int field_num, const std::string &class_name, const tl::arg &a,
+                                         bool is_default) const override;
+  std::string gen_constructor_end(const tl::tl_combinator *t, int fields_num, bool is_default) const override;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_writer_jni_cpp.cpp b/libs/tdlib/td/td/generate/tl_writer_jni_cpp.cpp
new file mode 100644
index 0000000000..b8c1c9e324
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_writer_jni_cpp.cpp
@@ -0,0 +1,636 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_writer_jni_cpp.h"
+
+#include <cassert>
+#include <cstdio>
+
+namespace td {
+
+bool TD_TL_writer_jni_cpp::is_built_in_simple_type(const std::string &name) const {
+  return name == "Bool" || name == "Int32" || name == "Int53" || name == "Int64" || name == "Double" ||
+         name == "String" || name == "Bytes";
+}
+
+bool TD_TL_writer_jni_cpp::is_built_in_complex_type(const std::string &name) const {
+  return name == "Vector";
+}
+
+int TD_TL_writer_jni_cpp::get_parser_type(const tl::tl_combinator *t, const std::string &parser_name) const {
+  return 1;
+}
+
+int TD_TL_writer_jni_cpp::get_additional_function_type(const std::string &additional_function_name) const {
+  return 1;
+}
+
+std::vector<std::string> TD_TL_writer_jni_cpp::get_parsers() const {
+  std::vector<std::string> parsers;
+  parsers.push_back("JNIEnv *env, jobject");
+  return parsers;
+}
+
+std::vector<std::string> TD_TL_writer_jni_cpp::get_storers() const {
+  std::vector<std::string> storers;
+  storers.push_back("JNIEnv *env, jobject");
+  storers.push_back("TlStorerToString");
+  return storers;
+}
+
+std::vector<std::string> TD_TL_writer_jni_cpp::get_additional_functions() const {
+  std::vector<std::string> additional_functions;
+  additional_functions.push_back("init_jni_vars");
+  return additional_functions;
+}
+
+std::string TD_TL_writer_jni_cpp::gen_base_type_class_name(int arity) const {
+  assert(arity == 0);
+  return "Object";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_base_tl_class_name() const {
+  return "Object";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_class_begin(const std::string &class_name, const std::string &base_class_name,
+                                                  bool is_proxy) const {
+  return "\n"
+         "jclass " +
+         class_name + "::Class;\n";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_field_definition(const std::string &class_name, const std::string &type_name,
+                                                       const std::string &field_name) const {
+  return "jfieldID " + class_name + "::" + field_name + "fieldID;\n";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_constructor_id_store(std::int32_t id, int storer_type) const {
+  return "";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_vector_fetch(std::string field_name, const tl::tl_tree_type *t,
+                                                   const std::vector<tl::var_description> &vars,
+                                                   int parser_type) const {
+  std::string vector_type = gen_type_name(t);
+
+  if (vector_type == "bool") {
+    assert(false);  // TODO
+  }
+
+  std::string fetch_object = "jni::fetch_object(env, p, " + field_name + "fieldID)";
+  std::string array_type;
+  if (vector_type == "std::int32_t") {
+    array_type = "jintArray";
+  }
+  if (vector_type == "std::int64_t") {
+    array_type = "jlongArray";
+  }
+  if (vector_type == "double") {
+    array_type = "jdoubleArray";
+  }
+
+  if (!array_type.empty()) {
+    return "jni::fetch_vector(env, (" + array_type + ")" + fetch_object + ");";
+  }
+
+  std::string template_type;
+  if (vector_type == string_type) {
+    template_type = "std::string";
+  } else if (vector_type.compare(0, 11, "std::vector") == 0) {
+    const tl::tl_tree_type *child = static_cast<const tl::tl_tree_type *>(t->children[0]);
+    template_type = gen_type_name(child);
+    if (template_type.compare(0, 10, "object_ptr") == 0) {
+      template_type = gen_main_class_name(child->type);
+    }
+    template_type = "std::vector<" + template_type + ">";
+  } else if (vector_type == bytes_type) {
+    std::fprintf(stderr, "Vector of Bytes is not supported\n");
+    assert(false);
+  } else {
+    assert(vector_type.compare(0, 10, "object_ptr") == 0);
+    template_type = gen_main_class_name(t->type);
+  }
+  return "jni::FetchVector<" + template_type + ">::fetch(env, (jobjectArray)" + fetch_object + ");";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_type_fetch(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                                                 const std::vector<tl::var_description> &vars, int parser_type) const {
+  const tl::tl_type *t = tree_type->type;
+  const std::string &name = t->name;
+
+  assert(!(t->flags & tl::FLAG_DEFAULT_CONSTRUCTOR));
+  assert(parser_type == 1);
+
+  if (!(tree_type->flags & tl::FLAG_BARE)) {
+    if (is_type_bare(t)) {
+      if (field_name != "") {
+        std::fprintf(stderr, "Do not use non-bare fields with bare type %s\n", name.c_str());
+        //        assert(false);
+      }
+    }
+  } else {
+    assert(is_type_bare(t));
+  }
+
+  std::string res_begin;
+  if (!field_name.empty()) {
+    res_begin = field_name + " = ";
+  }
+
+  std::string res;
+  assert(name != "#");
+  if (field_name.empty()) {
+    if (name == "Bool") {
+      return "env->CallObjectMethod(p, jni::BooleanGetValueMethodID)";
+    } else if (name == "Int32") {
+      return "env->CallObjectMethod(p, jni::IntegerGetValueMethodID)";
+    } else if (name == "Int53" || name == "Int64") {
+      return "env->CallObjectMethod(p, jni::LongGetValueMethodID)";
+    } else if (name == "Double") {
+      return "env->CallObjectMethod(p, jni::DoubleGetValueMethodID)";
+    } else if (name == "String") {
+      return "jni::from_jstring(env, (jstring)p)";
+    } else if (name == "Bytes") {
+      return "jni::from_bytes(env, (jbyteArray)p)";
+    }
+  }
+
+  if (name == "Bool") {
+    res = "(env->GetBooleanField(p, " + field_name + "fieldID) != 0)";
+  } else if (name == "Int32") {
+    res = "env->GetIntField(p, " + field_name + "fieldID)";
+  } else if (name == "Int53" || name == "Int64") {
+    res = "env->GetLongField(p, " + field_name + "fieldID)";
+  } else if (name == "Double") {
+    res = "env->GetDoubleField(p, " + field_name + "fieldID)";
+  } else if (name == "String") {
+    res = "jni::fetch_string(env, p, " + field_name + "fieldID)";
+  } else if (name == "Bytes") {
+    res = "jni::from_bytes(env, (jbyteArray)jni::fetch_object(env, p, " + field_name + "fieldID))";
+  } else if (name == "Vector") {
+    const tl::tl_tree_type *child = static_cast<const tl::tl_tree_type *>(tree_type->children[0]);
+    res = gen_vector_fetch(field_name, child, vars, parser_type);
+  } else {
+    if (field_name == "") {
+      return gen_main_class_name(tree_type->type) + "::fetch(env, p)";
+    }
+    res = "jni::fetch_tl_object<" + gen_main_class_name(tree_type->type) + ">(env, jni::fetch_object(env, p, " +
+          field_name + "fieldID));";
+  }
+  return res_begin + res;
+}
+
+std::string TD_TL_writer_jni_cpp::gen_field_fetch(int field_num, const tl::arg &a,
+                                                  std::vector<tl::var_description> &vars, bool flat,
+                                                  int parser_type) const {
+  assert(parser_type >= 0);
+  std::string field_name = (parser_type == 0 ? (field_num == 0 ? ": " : ", ") : "res->") + gen_field_name(a.name);
+
+  assert(a.exist_var_num == -1);
+  if (a.type->get_type() == tl::NODE_TYPE_VAR_TYPE) {
+    assert(parser_type == 1);
+
+    const tl::tl_tree_var_type *t = static_cast<const tl::tl_tree_var_type *>(a.type);
+    assert(a.flags == tl::FLAG_EXCL);
+
+    assert(a.var_num == -1);
+
+    assert(t->var_num >= 0);
+    assert(vars[t->var_num].is_type);
+    assert(!vars[t->var_num].is_stored);
+    vars[t->var_num].is_stored = true;
+
+    assert(false && "not supported");
+    return "  " + field_name + " = " + gen_base_function_class_name() + "::fetch(env, p);\n";
+  }
+
+  assert(!(a.flags & tl::FLAG_EXCL));
+  assert(!(a.flags & tl::FLAG_OPT_VAR));
+
+  if (flat) {
+    //    TODO
+    //    return gen_field_fetch(const tl::arg &a, std::vector<tl::var_description> &vars, int num, bool flat);
+  }
+
+  assert(a.var_num == -1);
+
+  assert(a.type->get_type() == tl::NODE_TYPE_TYPE);
+  const tl::tl_tree_type *tree_type = static_cast<tl::tl_tree_type *>(a.type);
+
+  assert(parser_type != 0);
+  return "  " + gen_type_fetch(field_name, tree_type, vars, parser_type) + ";\n";
+}
+
+std::string TD_TL_writer_jni_cpp::get_pretty_field_name(std::string field_name) const {
+  return gen_java_field_name(TD_TL_writer_cpp::get_pretty_field_name(field_name));
+}
+
+std::string TD_TL_writer_jni_cpp::get_pretty_class_name(std::string class_name) const {
+  if (class_name == "vector") {
+    return "Array";
+  }
+  return gen_basic_java_class_name(class_name);
+}
+
+std::string TD_TL_writer_jni_cpp::gen_vector_store(const std::string &field_name, const tl::tl_tree_type *t,
+                                                   const std::vector<tl::var_description> &vars,
+                                                   int storer_type) const {
+  if (storer_type == 1) {
+    return TD_TL_writer_cpp::gen_vector_store(field_name, t, vars, storer_type);
+  }
+
+  std::string vector_type = gen_type_name(t);
+
+  if (vector_type == "bool") {
+    assert(false);  // TODO
+  }
+  if (vector_type == "std::int32_t" || vector_type == "std::int64_t" || vector_type == "double" ||
+      vector_type == string_type || vector_type.compare(0, 11, "std::vector") == 0 ||
+      vector_type.compare(0, 10, "object_ptr") == 0) {
+    return "{ "
+           "auto arr_tmp_ = jni::store_vector(env, " +
+           field_name +
+           "); "
+           "if (arr_tmp_) { "
+           "env->SetObjectField(s, " +
+           field_name +
+           "fieldID, arr_tmp_); "
+           "env->DeleteLocalRef(arr_tmp_); "
+           "} }";
+  }
+  if (vector_type == bytes_type) {
+    std::fprintf(stderr, "Vector of Bytes is not supported\n");
+    assert(false);
+  }
+
+  assert(false);
+  return "";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_type_store(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                                                 const std::vector<tl::var_description> &vars, int storer_type) const {
+  const tl::tl_type *t = tree_type->type;
+  const std::string &name = t->name;
+
+  assert(!field_name.empty());
+
+  assert(!(t->flags & tl::FLAG_DEFAULT_CONSTRUCTOR));
+
+  if (!(tree_type->flags & tl::FLAG_BARE)) {
+    if (storer_type == 0) {
+      if (is_type_bare(t)) {
+        std::fprintf(stderr, "Do not use non-bare fields with bare type %s\n", name.c_str());
+        //        assert(false);
+      }
+    }
+  } else {
+    assert(is_type_bare(t));
+  }
+
+  std::string res;
+  if (name == "Int32" || name == "Int53" || name == "Int64" || name == "Double" || name == "Bool" || name == "String") {
+    if (storer_type == 1) {
+      res = "s.store_field(\"" + get_pretty_field_name(field_name) + "\", " + field_name + ");";
+    } else if (name == "Bool") {
+      res = "env->SetBooleanField(s, " + field_name + "fieldID, " + field_name + ");";
+    } else if (name == "Int32") {
+      res = "env->SetIntField(s, " + field_name + "fieldID, " + field_name + ");";
+    } else if (name == "Int53" || name == "Int64") {
+      res = "env->SetLongField(s, " + field_name + "fieldID, " + field_name + ");";
+    } else if (name == "Double") {
+      res = "env->SetDoubleField(s, " + field_name + "fieldID, " + field_name + ");";
+    } else if (name == "String") {
+      res = "{ jstring nextString = jni::to_jstring(env, " + field_name +
+            "); if (nextString) { env->SetObjectField(s, " + field_name +
+            "fieldID, nextString); env->DeleteLocalRef(nextString); } }";
+    } else {
+      assert(false);
+    }
+  } else if (name == "Bytes") {
+    if (storer_type == 1) {
+      res = "s.store_bytes_field(\"" + get_pretty_field_name(field_name) + "\", " + field_name + ");";
+    } else {
+      res = "{ jbyteArray nextBytes = jni::to_bytes(env, " + field_name +
+            "); if (nextBytes) { env->SetObjectField(s, " + field_name +
+            "fieldID, nextBytes); env->DeleteLocalRef(nextBytes); } }";
+    }
+  } else if (name == "Vector") {
+    const tl::tl_tree_type *child = static_cast<const tl::tl_tree_type *>(tree_type->children[0]);
+    res = gen_vector_store(field_name, child, vars, storer_type);
+  } else {
+    if (storer_type == 1) {
+      res = "if (" + field_name + " == nullptr) { s.store_field(\"" + get_pretty_field_name(field_name) +
+            "\", \"null\"); } else { " + field_name + "->store(s, \"" + get_pretty_field_name(field_name) + "\"); }";
+    } else {
+      res = "if (" + field_name + " != nullptr) { jobject next; " + field_name +
+            "->store(env, next); if (next) { env->SetObjectField(s, " + field_name +
+            "fieldID, next); env->DeleteLocalRef(next); } }";
+    }
+    assert(tree_type->children.empty());
+  }
+  return res;
+}
+
+std::string TD_TL_writer_jni_cpp::gen_field_store(const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                                                  int storer_type) const {
+  std::string field_name = gen_field_name(a.name);
+  std::string shift = storer_type == 1 ? "    " : "  ";
+
+  assert(a.exist_var_num == -1);
+  if (a.type->get_type() == tl::NODE_TYPE_VAR_TYPE) {
+    const tl::tl_tree_var_type *t = static_cast<const tl::tl_tree_var_type *>(a.type);
+    assert(a.flags == tl::FLAG_EXCL);
+
+    assert(a.var_num == -1);
+
+    assert(t->var_num >= 0);
+    assert(!vars[t->var_num].is_stored);
+    vars[t->var_num].is_stored = true;
+    assert(vars[t->var_num].is_type);
+
+    assert(false && "not supported");
+    return shift + field_name + "->store(env, s);\n";
+  }
+
+  assert(!(a.flags & tl::FLAG_EXCL));
+  assert(!(a.flags & tl::FLAG_OPT_VAR));
+
+  if (flat) {
+    //    TODO
+    //    return gen_field_store(const tl::arg &a, std::vector<tl::var_description> &vars, bool flat, int storer_type);
+  }
+
+  assert(a.var_num == -1);
+  assert(a.type->get_type() == tl::NODE_TYPE_TYPE);
+  const tl::tl_tree_type *tree_type = static_cast<tl::tl_tree_type *>(a.type);
+  return shift + gen_type_store(field_name, tree_type, vars, storer_type) + "\n";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_get_id(const std::string &class_name, std::int32_t id, bool is_proxy) const {
+  if (is_proxy) {
+    return "";
+  }
+  return "\nconst std::int32_t " + class_name + "::ID;\n";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_fetch_function_begin(const std::string &parser_name,
+                                                           const std::string &class_name, int arity,
+                                                           std::vector<tl::var_description> &vars,
+                                                           int parser_type) const {
+  for (std::size_t i = 0; i < vars.size(); i++) {
+    assert(vars[i].is_stored == false);
+  }
+
+  std::string fetched_type = "object_ptr<" + class_name + "> ";
+  assert(arity == 0);
+
+  assert(parser_type != 0);
+
+  return "\n" + fetched_type + class_name + "::fetch(" + parser_name + " &p) {\n" +
+         (parser_type == -1 ? ""
+                            : "  if (p == nullptr) return nullptr;\n"
+                              "  " +
+                                  fetched_type + "res = make_object<" + class_name + ">();\n");
+}
+
+std::string TD_TL_writer_jni_cpp::gen_fetch_function_end(int field_num, const std::vector<tl::var_description> &vars,
+                                                         int parser_type) const {
+  for (std::size_t i = 0; i < vars.size(); i++) {
+    assert(vars[i].is_stored);
+  }
+
+  assert(parser_type != 0);
+
+  if (parser_type == -1) {
+    return "}\n";
+  }
+
+  return "  return res;\n"
+         "}\n";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_fetch_function_result_begin(const std::string &parser_name,
+                                                                  const std::string &class_name,
+                                                                  const tl::tl_tree *result) const {
+  return "\n" + class_name + "::ReturnType " + class_name + "::fetch_result(" + parser_name +
+         " &p) {\n"
+         "  if (p == nullptr) return ReturnType();\n" +
+         "  return ";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_fetch_function_result_end() const {
+  return ";\n"
+         "}\n";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_fetch_function_result_any_begin(const std::string &parser_name,
+                                                                      const std::string &class_name,
+                                                                      bool is_proxy) const {
+  return "";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_fetch_function_result_any_end(bool is_proxy) const {
+  return "";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_store_function_begin(const std::string &storer_name,
+                                                           const std::string &class_name, int arity,
+                                                           std::vector<tl::var_description> &vars,
+                                                           int storer_type) const {
+  for (std::size_t i = 0; i < vars.size(); i++) {
+    vars[i].is_stored = false;
+  }
+
+  if (storer_type == -1) {
+    return "";
+  }
+
+  assert(arity == 0);
+  return "\n"
+         "void " +
+         class_name + "::store(" + storer_name + " &s" +
+         std::string(storer_type <= 0 ? "" : ", const char *field_name") + ") const {\n" +
+         (storer_type <= 0 ? "  s = env->AllocObject(Class);\n"
+                             "  if (!s) { return; }\n"
+                           : "  if (!LOG_IS_STRIPPED(ERROR)) {\n"
+                             "    s.store_class_begin(field_name, \"" +
+                                 get_pretty_class_name(class_name) + "\");\n");
+}
+
+std::string TD_TL_writer_jni_cpp::gen_fetch_switch_begin() const {
+  return "  if (p == nullptr) { return nullptr; }\n"
+         "  switch (env->CallIntMethod(p, jni::GetConstructorID)) {\n";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_fetch_switch_case(const tl::tl_combinator *t, int arity) const {
+  assert(arity == 0);
+  return "    case " + gen_class_name(t->name) +
+         "::ID:\n"
+         "      return " +
+         gen_class_name(t->name) + "::fetch(env, p);\n";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_fetch_switch_end() const {
+  return "    default:\n"
+         "      LOG(WARNING) << \"Unknown constructor found\";\n"
+         "      return nullptr;\n"
+         "  }\n";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_java_field_name(std::string name) const {
+  std::string result;
+  bool next_to_upper = false;
+  for (std::size_t i = 0; i < name.size(); i++) {
+    if (!is_alnum(name[i])) {
+      next_to_upper = true;
+      continue;
+    }
+    if (next_to_upper) {
+      result += to_upper(name[i]);
+      next_to_upper = false;
+    } else {
+      result += name[i];
+    }
+  }
+  return result;
+}
+
+std::string TD_TL_writer_jni_cpp::gen_basic_java_class_name(std::string name) const {
+  std::string result;
+  bool next_to_upper = true;
+  for (std::size_t i = 0; i < name.size(); i++) {
+    if (!is_alnum(name[i])) {
+      next_to_upper = true;
+      continue;
+    }
+    if (next_to_upper) {
+      result += to_upper(name[i]);
+      next_to_upper = false;
+    } else {
+      result += name[i];
+    }
+  }
+  return result;
+}
+
+std::string TD_TL_writer_jni_cpp::gen_java_class_name(std::string name) const {
+  return "(PSLICE() << package_name << \"/TdApi$" + gen_basic_java_class_name(name) + "\").c_str()";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_type_signature(const tl::tl_tree_type *tree_type) const {
+  const tl::tl_type *t = tree_type->type;
+  const std::string &name = t->name;
+
+  assert(name != "#");
+  assert(name != gen_base_tl_class_name());
+  if (name == "Bool") {
+    return "Z";
+  } else if (name == "Int32") {
+    return "I";
+  } else if (name == "Int53" || name == "Int64") {
+    return "J";
+  } else if (name == "Double") {
+    return "D";
+  } else if (name == "String") {
+    return "Ljava/lang/String;";
+  } else if (name == "Bytes") {
+    return "[B";
+  } else if (name == "Vector") {
+    const tl::tl_tree_type *child = static_cast<const tl::tl_tree_type *>(tree_type->children[0]);
+    return "[" + gen_type_signature(child);
+  } else {
+    return "L%PACKAGE_NAME%/TdApi$" + gen_basic_java_class_name(gen_main_class_name(t)) + ";";
+  }
+  assert(false);
+  return "";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_additional_function(const std::string &function_name, const tl::tl_combinator *t,
+                                                          bool is_function) const {
+  assert(function_name == "init_jni_vars");
+  std::string class_name = gen_class_name(t->name);
+  std::string class_name_class = "Class";
+  std::string res =
+      "\n"
+      "void " +
+      class_name + "::" + function_name +
+      "(JNIEnv *env, const char *package_name) {\n"
+      "  " +
+      class_name_class + " = jni::get_jclass(env, " + gen_java_class_name(gen_class_name(t->name)) + ");\n";
+
+  if (t->args.size()) {
+    for (std::size_t i = 0; i < t->args.size(); i++) {
+      const tl::arg &a = t->args[i];
+      assert(a.type->get_type() == tl::NODE_TYPE_TYPE);
+      const tl::tl_tree_type *tree_type = static_cast<tl::tl_tree_type *>(a.type);
+
+      std::string field_name = gen_field_name(a.name);
+      assert(field_name.size());
+      std::string java_field_name = gen_java_field_name(std::string(field_name, 0, field_name.size() - 1));
+
+      std::string type_signature = gen_type_signature(tree_type);
+      if (type_signature.find("%PACKAGE_NAME%") == std::string::npos) {
+        type_signature = '"' + type_signature + '"';
+      } else {
+        std::string new_type_signature = "(PSLICE()";
+        std::size_t pos = type_signature.find("%PACKAGE_NAME%");
+        while (pos != std::string::npos) {
+          new_type_signature += " << \"" + type_signature.substr(0, pos) + "\" << package_name";
+          type_signature = type_signature.substr(pos + 14);
+          pos = type_signature.find("%PACKAGE_NAME%");
+        }
+        if (!type_signature.empty()) {
+          new_type_signature += " << \"" + type_signature + "\"";
+        }
+        type_signature = new_type_signature + ").c_str()";
+      }
+      res += "  " + field_name + "fieldID = jni::get_field_id(env, " + class_name_class + ", \"" + java_field_name +
+             "\", " + type_signature + ");\n";
+    }
+  }
+  res += "}\n";
+  return res;
+}
+
+std::string TD_TL_writer_jni_cpp::gen_additional_proxy_function_begin(const std::string &function_name,
+                                                                      const tl::tl_type *type,
+                                                                      const std::string &class_name, int arity,
+                                                                      bool is_function) const {
+  assert(function_name == "init_jni_vars");
+  assert(arity == 0);
+  return "\n"
+         "void " +
+         class_name + "::" + function_name +
+         "(JNIEnv *env, const char *package_name) {\n"
+         "  Class = jni::get_jclass(env, " +
+         gen_java_class_name(class_name) + ");\n";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_additional_proxy_function_case(const std::string &function_name,
+                                                                     const tl::tl_type *type,
+                                                                     const std::string &class_name, int arity) const {
+  assert(function_name == "init_jni_vars");
+  assert(arity == 0);
+  return "  " + class_name + "::" + function_name + "(env, package_name);\n";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_additional_proxy_function_case(const std::string &function_name,
+                                                                     const tl::tl_type *type,
+                                                                     const tl::tl_combinator *t, int arity,
+                                                                     bool is_function) const {
+  assert(function_name == "init_jni_vars");
+  assert(arity == 0);
+  return "  " + gen_class_name(t->name) + "::" + function_name + "(env, package_name);\n";
+}
+
+std::string TD_TL_writer_jni_cpp::gen_additional_proxy_function_end(const std::string &function_name,
+                                                                    const tl::tl_type *type, bool is_function) const {
+  assert(function_name == "init_jni_vars");
+  return "}\n";
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_writer_jni_cpp.h b/libs/tdlib/td/td/generate/tl_writer_jni_cpp.h
new file mode 100644
index 0000000000..414cb4c64c
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_writer_jni_cpp.h
@@ -0,0 +1,109 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "tl_writer_cpp.h"
+
+#include <cstddef>
+#include <cstdint>
+#include <string>
+#include <vector>
+
+namespace td {
+
+class TD_TL_writer_jni_cpp : public TD_TL_writer_cpp {
+  std::string gen_vector_fetch(std::string field_name, const tl::tl_tree_type *t,
+                               const std::vector<tl::var_description> &vars, int parser_type) const;
+
+  std::string gen_vector_store(const std::string &field_name, const tl::tl_tree_type *t,
+                               const std::vector<tl::var_description> &vars, int storer_type) const;
+
+  std::string package_name;
+
+  std::string gen_java_field_name(std::string name) const;
+
+  std::string gen_basic_java_class_name(std::string name) const;
+
+  std::string gen_java_class_name(std::string name) const;
+
+  std::string gen_type_signature(const tl::tl_tree_type *tree_type) const;
+
+  std::string get_pretty_field_name(std::string field_name) const override;
+
+  std::string get_pretty_class_name(std::string class_name) const override;
+
+ public:
+  TD_TL_writer_jni_cpp(const std::string &tl_name, const std::string &string_type, const std::string &bytes_type,
+                       const std::vector<std::string> &ext_include)
+      : TD_TL_writer_cpp(tl_name, string_type, bytes_type, ext_include) {
+  }
+
+  bool is_built_in_simple_type(const std::string &name) const override;
+  bool is_built_in_complex_type(const std::string &name) const override;
+
+  int get_parser_type(const tl::tl_combinator *t, const std::string &parser_name) const override;
+  int get_additional_function_type(const std::string &additional_function_name) const override;
+  std::vector<std::string> get_parsers() const override;
+  std::vector<std::string> get_storers() const override;
+  std::vector<std::string> get_additional_functions() const override;
+
+  std::string gen_base_type_class_name(int arity) const override;
+  std::string gen_base_tl_class_name() const override;
+
+  std::string gen_class_begin(const std::string &class_name, const std::string &base_class_name,
+                              bool is_proxy) const override;
+
+  std::string gen_field_definition(const std::string &class_name, const std::string &type_name,
+                                   const std::string &field_name) const override;
+
+  std::string gen_constructor_id_store(std::int32_t id, int storer_type) const override;
+
+  std::string gen_field_fetch(int field_num, const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                              int parser_type) const override;
+  std::string gen_field_store(const tl::arg &a, std::vector<tl::var_description> &vars, bool flat,
+                              int storer_type) const override;
+  std::string gen_type_fetch(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                             const std::vector<tl::var_description> &vars, int parser_type) const override;
+  std::string gen_type_store(const std::string &field_name, const tl::tl_tree_type *tree_type,
+                             const std::vector<tl::var_description> &vars, int storer_type) const override;
+
+  std::string gen_get_id(const std::string &class_name, std::int32_t id, bool is_proxy) const override;
+
+  std::string gen_fetch_function_begin(const std::string &parser_name, const std::string &class_name, int arity,
+                                       std::vector<tl::var_description> &vars, int parser_type) const override;
+  std::string gen_fetch_function_end(int field_num, const std::vector<tl::var_description> &vars,
+                                     int parser_type) const override;
+
+  std::string gen_fetch_function_result_begin(const std::string &parser_name, const std::string &class_name,
+                                              const tl::tl_tree *result) const override;
+  std::string gen_fetch_function_result_end() const override;
+  std::string gen_fetch_function_result_any_begin(const std::string &parser_name, const std::string &class_name,
+                                                  bool is_proxy) const override;
+  std::string gen_fetch_function_result_any_end(bool is_proxy) const override;
+
+  std::string gen_store_function_begin(const std::string &storer_name, const std::string &class_name, int arity,
+                                       std::vector<tl::var_description> &vars, int storer_type) const override;
+
+  std::string gen_fetch_switch_begin() const override;
+  std::string gen_fetch_switch_case(const tl::tl_combinator *t, int arity) const override;
+  std::string gen_fetch_switch_end() const override;
+
+  std::string gen_additional_function(const std::string &function_name, const tl::tl_combinator *t,
+                                      bool is_function) const override;
+  std::string gen_additional_proxy_function_begin(const std::string &function_name, const tl::tl_type *type,
+                                                  const std::string &class_name, int arity,
+                                                  bool is_function) const override;
+  std::string gen_additional_proxy_function_case(const std::string &function_name, const tl::tl_type *type,
+                                                 const std::string &class_name, int arity) const override;
+  std::string gen_additional_proxy_function_case(const std::string &function_name, const tl::tl_type *type,
+                                                 const tl::tl_combinator *t, int arity,
+                                                 bool is_function) const override;
+  std::string gen_additional_proxy_function_end(const std::string &function_name, const tl::tl_type *type,
+                                                bool is_function) const override;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_writer_jni_h.cpp b/libs/tdlib/td/td/generate/tl_writer_jni_h.cpp
new file mode 100644
index 0000000000..d974d454d9
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_writer_jni_h.cpp
@@ -0,0 +1,194 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_writer_jni_h.h"
+
+#include <cassert>
+
+namespace td {
+
+bool TD_TL_writer_jni_h::is_built_in_simple_type(const std::string &name) const {
+  return name == "Bool" || name == "Int32" || name == "Int53" || name == "Int64" || name == "Double" ||
+         name == "String" || name == "Bytes";
+}
+
+bool TD_TL_writer_jni_h::is_built_in_complex_type(const std::string &name) const {
+  return name == "Vector";
+}
+
+int TD_TL_writer_jni_h::get_additional_function_type(const std::string &additional_function_name) const {
+  if (additional_function_name == "init_jni_vars") {
+    return 1;
+  }
+  return TD_TL_writer_h::get_additional_function_type(additional_function_name);
+}
+
+int TD_TL_writer_jni_h::get_parser_type(const tl::tl_combinator *t, const std::string &parser_name) const {
+  return 1;
+}
+
+std::vector<std::string> TD_TL_writer_jni_h::get_parsers() const {
+  std::vector<std::string> parsers;
+  parsers.push_back("JNIEnv *env, jobject");
+  return parsers;
+}
+
+std::vector<std::string> TD_TL_writer_jni_h::get_storers() const {
+  std::vector<std::string> storers;
+  storers.push_back("JNIEnv *env, jobject");
+  storers.push_back("TlStorerToString");
+  return storers;
+}
+
+std::vector<std::string> TD_TL_writer_jni_h::get_additional_functions() const {
+  std::vector<std::string> additional_functions = TD_TL_writer_h::get_additional_functions();
+  additional_functions.push_back("init_jni_vars");
+  return additional_functions;
+}
+
+std::string TD_TL_writer_jni_h::gen_base_type_class_name(int arity) const {
+  assert(arity == 0);
+  return "Object";
+}
+
+std::string TD_TL_writer_jni_h::gen_base_tl_class_name() const {
+  return "Object";
+}
+
+std::string TD_TL_writer_jni_h::gen_output_begin() const {
+  std::string ext_include_str;
+  for (auto &it : ext_include) {
+    ext_include_str += "#include " + it + "\n";
+  }
+  return "#pragma once\n\n"
+         "#include \"td/tl/TlObject.h\"\n\n"
+         "#include <cstdint>\n"
+         "#include <memory>\n"
+         "#include <utility>\n"
+         "#include <vector>\n\n"
+         "#include <jni.h>\n\n" +
+         ext_include_str +
+         "\n"
+
+         "namespace td {\n" +
+         forward_declaration("TlStorerToString") +
+         "\n"
+         "namespace " +
+         tl_name +
+         " {\n\n"
+
+         "class " +
+         gen_base_tl_class_name() +
+         ";\n"
+         "using BaseObject = " +
+         gen_base_tl_class_name() +
+         ";\n\n"
+
+         "template <class Type>\n"
+         "using object_ptr = ::td::tl_object_ptr<Type>;\n\n"
+         "template <class Type, class... Args>\n"
+         "object_ptr<Type> make_object(Args &&... args) {\n"
+         "  return object_ptr<Type>(new Type(std::forward<Args>(args)...));\n"
+         "}\n\n"
+
+         "template <class ToType, class FromType>\n"
+         "object_ptr<ToType> move_object_as(FromType &&from) {\n"
+         "  return object_ptr<ToType>(static_cast<ToType *>(from.release()));\n"
+         "}\n\n"
+
+         "std::string to_string(const BaseObject &value);\n\n"
+
+         "template <class T>\n"
+         "std::string to_string(const object_ptr<T> &value) {\n"
+         "  if (value == nullptr) {\n"
+         "    return \"null\";\n"
+         "  }\n"
+         "\n"
+         "  return to_string(*value);\n"
+         "}\n\n";
+}
+
+std::string TD_TL_writer_jni_h::gen_class_begin(const std::string &class_name, const std::string &base_class_name,
+                                                bool is_proxy) const {
+  if (class_name == gen_base_tl_class_name()) {
+    return "class " + class_name +
+           " {\n"
+           " public:\n"
+           "  virtual ~" +
+           class_name +
+           "() {\n"
+           "  }\n\n" +
+           "  virtual void store(JNIEnv *env, jobject &s) const {\n"
+           "  }\n\n"
+           "  virtual void store(TlStorerToString &s, const char *field_name) const = 0;\n\n"
+           "  static jclass Class;\n";
+  }
+  return "class " + class_name + (!is_proxy ? " final " : "") + ": public " + base_class_name +
+         " {\n"
+         " public:\n"
+         "  static jclass Class;\n";
+}
+
+std::string TD_TL_writer_jni_h::gen_field_definition(const std::string &class_name, const std::string &type_name,
+                                                     const std::string &field_name) const {
+  return TD_TL_writer_h::gen_field_definition(class_name, type_name, field_name) + "  static jfieldID " + field_name +
+         "fieldID;\n";
+}
+
+std::string TD_TL_writer_jni_h::gen_additional_function(const std::string &function_name, const tl::tl_combinator *t,
+                                                        bool is_function) const {
+  if (function_name == "init_jni_vars") {
+    return "\n"
+           "  static void " +
+           function_name + "(JNIEnv *env, const char *package_name);\n";
+  }
+
+  return TD_TL_writer_h::gen_additional_function(function_name, t, is_function);
+}
+
+std::string TD_TL_writer_jni_h::gen_additional_proxy_function_begin(const std::string &function_name,
+                                                                    const tl::tl_type *type,
+                                                                    const std::string &class_name, int arity,
+                                                                    bool is_function) const {
+  if (function_name == "init_jni_vars") {
+    return "\n"
+           "  static void " +
+           function_name + "(JNIEnv *env, const char *package_name);\n";
+  }
+
+  return TD_TL_writer_h::gen_additional_proxy_function_begin(function_name, type, class_name, arity, is_function);
+}
+
+std::string TD_TL_writer_jni_h::gen_additional_proxy_function_case(const std::string &function_name,
+                                                                   const tl::tl_type *type,
+                                                                   const std::string &class_name, int arity) const {
+  if (function_name == "init_jni_vars") {
+    return "";
+  }
+
+  return TD_TL_writer_h::gen_additional_proxy_function_case(function_name, type, class_name, arity);
+}
+
+std::string TD_TL_writer_jni_h::gen_additional_proxy_function_case(const std::string &function_name,
+                                                                   const tl::tl_type *type, const tl::tl_combinator *t,
+                                                                   int arity, bool is_function) const {
+  if (function_name == "init_jni_vars") {
+    return "";
+  }
+
+  return TD_TL_writer_h::gen_additional_proxy_function_case(function_name, type, t, arity, is_function);
+}
+
+std::string TD_TL_writer_jni_h::gen_additional_proxy_function_end(const std::string &function_name,
+                                                                  const tl::tl_type *type, bool is_function) const {
+  if (function_name == "init_jni_vars") {
+    return "";
+  }
+
+  return TD_TL_writer_h::gen_additional_proxy_function_end(function_name, type, is_function);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_writer_jni_h.h b/libs/tdlib/td/td/generate/tl_writer_jni_h.h
new file mode 100644
index 0000000000..6834937858
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_writer_jni_h.h
@@ -0,0 +1,57 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "tl_writer_h.h"
+
+#include <string>
+#include <vector>
+
+namespace td {
+
+class TD_TL_writer_jni_h : public TD_TL_writer_h {
+ public:
+  TD_TL_writer_jni_h(const std::string &tl_name, const std::string &string_type, const std::string &bytes_type,
+                     const std::vector<std::string> &ext_include)
+      : TD_TL_writer_h(tl_name, string_type, bytes_type, ext_include) {
+  }
+
+  bool is_built_in_simple_type(const std::string &name) const override;
+  bool is_built_in_complex_type(const std::string &name) const override;
+
+  int get_parser_type(const tl::tl_combinator *t, const std::string &parser_name) const override;
+  int get_additional_function_type(const std::string &additional_function_name) const override;
+  std::vector<std::string> get_parsers() const override;
+  std::vector<std::string> get_storers() const override;
+  std::vector<std::string> get_additional_functions() const override;
+
+  std::string gen_base_type_class_name(int arity) const override;
+  std::string gen_base_tl_class_name() const override;
+
+  std::string gen_output_begin() const override;
+
+  std::string gen_class_begin(const std::string &class_name, const std::string &base_class_name,
+                              bool is_proxy) const override;
+
+  std::string gen_field_definition(const std::string &class_name, const std::string &type_name,
+                                   const std::string &field_name) const override;
+
+  std::string gen_additional_function(const std::string &function_name, const tl::tl_combinator *t,
+                                      bool is_function) const override;
+  std::string gen_additional_proxy_function_begin(const std::string &function_name, const tl::tl_type *type,
+                                                  const std::string &class_name, int arity,
+                                                  bool is_function) const override;
+  std::string gen_additional_proxy_function_case(const std::string &function_name, const tl::tl_type *type,
+                                                 const std::string &class_name, int arity) const override;
+  std::string gen_additional_proxy_function_case(const std::string &function_name, const tl::tl_type *type,
+                                                 const tl::tl_combinator *t, int arity,
+                                                 bool is_function) const override;
+  std::string gen_additional_proxy_function_end(const std::string &function_name, const tl::tl_type *type,
+                                                bool is_function) const override;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_writer_td.cpp b/libs/tdlib/td/td/generate/tl_writer_td.cpp
new file mode 100644
index 0000000000..4db4284626
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_writer_td.cpp
@@ -0,0 +1,254 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_writer_td.h"
+
+#include <cassert>
+
+namespace td {
+
+const int TD_TL_writer::MAX_ARITY;
+
+const std::string TD_TL_writer::base_type_class_names[MAX_ARITY + 1] = {"Object"};
+const std::string TD_TL_writer::base_tl_class_name = "TlObject";
+const std::string TD_TL_writer::base_function_class_name = "Function";
+
+int TD_TL_writer::get_max_arity() const {
+  return MAX_ARITY;
+}
+
+bool TD_TL_writer::is_built_in_simple_type(const std::string &name) const {
+  return name == "True" || name == "Bool" || name == "Int" || name == "Long" || name == "Double" || name == "String" ||
+         name == "Int32" || name == "Int53" || name == "Int64" || name == "Int128" || name == "Int256" ||
+         name == "Bytes";
+}
+
+bool TD_TL_writer::is_built_in_complex_type(const std::string &name) const {
+  return name == "Vector";
+}
+
+bool TD_TL_writer::is_type_bare(const tl::tl_type *t) const {
+  return t->simple_constructors <= 1 || (is_built_in_simple_type(t->name) && t->name != "Bool") ||
+         is_built_in_complex_type(t->name);
+}
+
+bool TD_TL_writer::is_combinator_supported(const tl::tl_combinator *constructor) const {
+  if (!TL_writer::is_combinator_supported(constructor)) {
+    return false;
+  }
+
+  for (std::size_t i = 0; i < constructor->args.size(); i++) {
+    if (constructor->args[i].type->get_type() == tl::NODE_TYPE_VAR_TYPE) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+int TD_TL_writer::get_storer_type(const tl::tl_combinator *t, const std::string &storer_name) const {
+  return storer_name == "TlStorerToString";
+}
+
+tl::TL_writer::Mode TD_TL_writer::get_parser_mode(int type) const {
+  if (tl_name == "td_api") {
+#ifndef TD_ENABLE_JNI  // we need to parse all types in order to implement toString
+    return Server;
+#endif
+  }
+  if (tl_name == "telegram_api") {
+    return Client;
+  }
+  return All;
+}
+
+tl::TL_writer::Mode TD_TL_writer::get_storer_mode(int type) const {
+  if (type == 1) {
+    return All;
+  }
+
+  if (tl_name == "td_api") {
+    return Server;
+  }
+  if (tl_name == "telegram_api") {
+    return Client;
+  }
+  return All;
+}
+
+std::vector<std::string> TD_TL_writer::get_parsers() const {
+  std::vector<std::string> parsers;
+  if (tl_name == "telegram_api") {
+    parsers.push_back("TlBufferParser");
+  } else if (tl_name == "mtproto_api" || tl_name == "secret_api") {
+    parsers.push_back("TlParser");
+  }
+  return parsers;
+}
+
+std::vector<std::string> TD_TL_writer::get_storers() const {
+  std::vector<std::string> storers;
+  if (tl_name == "telegram_api" || tl_name == "mtproto_api" || tl_name == "secret_api") {
+    storers.push_back("TlStorerCalcLength");
+    storers.push_back("TlStorerUnsafe");
+  }
+  storers.push_back("TlStorerToString");
+  return storers;
+}
+
+std::string TD_TL_writer::gen_base_tl_class_name() const {
+  return base_tl_class_name;
+}
+
+std::string TD_TL_writer::gen_base_type_class_name(int arity) const {
+  assert(arity == 0);
+  return base_type_class_names[arity];
+}
+
+std::string TD_TL_writer::gen_base_function_class_name() const {
+  return base_function_class_name;
+}
+
+std::string TD_TL_writer::gen_class_name(std::string name) const {
+  if (name == "Object") {
+    assert(false);
+  }
+  if (name == "#") {
+    return "std::int32_t";
+  }
+  for (std::size_t i = 0; i < name.size(); i++) {
+    if (!is_alnum(name[i])) {
+      name[i] = '_';
+    }
+  }
+  return name;
+}
+
+std::string TD_TL_writer::gen_field_name(std::string name) const {
+  for (std::size_t i = 0; i < name.size(); i++) {
+    if (!is_alnum(name[i])) {
+      name[i] = '_';
+    }
+  }
+  assert(name.size() > 0);
+  assert(name[name.size() - 1] != '_');
+  return name + "_";
+}
+
+std::string TD_TL_writer::gen_var_name(const tl::var_description &desc) const {
+  assert(!desc.is_type);
+
+  if (desc.parameter_num != -1) {
+    assert(false);
+  }
+  return "var" + int_to_string(desc.index);
+}
+
+std::string TD_TL_writer::gen_parameter_name(int index) const {
+  assert(false);
+  return std::string();
+}
+
+std::string TD_TL_writer::gen_type_name(const tl::tl_tree_type *tree_type) const {
+  const tl::tl_type *t = tree_type->type;
+  const std::string &name = t->name;
+
+  if (name == "#") {
+    return "std::int32_t";
+  }
+  if (name == "True") {
+    return "bool";
+  }
+  if (name == "Bool") {
+    return "bool";
+  }
+  if (name == "Int" || name == "Int32") {
+    return "std::int32_t";
+  }
+  if (name == "Long" || name == "Int53" || name == "Int64") {
+    return "std::int64_t";
+  }
+  if (name == "Double") {
+    return "double";
+  }
+  if (name == "String") {
+    return string_type;
+  }
+  if (name == "Int128") {
+    return "UInt128";
+  }
+  if (name == "Int256") {
+    return "UInt256";
+  }
+  if (name == "Bytes") {
+    return bytes_type;
+  }
+
+  if (name == "Vector") {
+    assert(t->arity == 1);
+    assert(tree_type->children.size() == 1);
+    assert(tree_type->children[0]->get_type() == tl::NODE_TYPE_TYPE);
+    const tl::tl_tree_type *child = static_cast<const tl::tl_tree_type *>(tree_type->children[0]);
+
+    return "std::vector<" + gen_type_name(child) + ">";
+  }
+
+  assert(!is_built_in_simple_type(name) && !is_built_in_complex_type(name));
+
+  for (std::size_t i = 0; i < tree_type->children.size(); i++) {
+    assert(tree_type->children[i]->get_type() == tl::NODE_TYPE_NAT_CONST);
+  }
+
+  return "object_ptr<" + gen_main_class_name(t) + ">";
+}
+
+std::string TD_TL_writer::gen_array_type_name(const tl::tl_tree_array *arr, const std::string &field_name) const {
+  assert(false);
+  return std::string();
+}
+
+std::string TD_TL_writer::gen_var_type_name() const {
+  return "object_ptr<" + gen_base_function_class_name() + ">";
+}
+
+std::string TD_TL_writer::gen_int_const(const tl::tl_tree *tree_c, const std::vector<tl::var_description> &vars) const {
+  assert(false);
+  return std::string();
+}
+
+std::string TD_TL_writer::gen_constructor_parameter(int field_num, const std::string &class_name, const tl::arg &a,
+                                                    bool is_default) const {
+  if (is_default) {
+    return "";
+  }
+
+  std::string field_type = gen_field_type(a);
+  if (field_type.empty()) {
+    return "";
+  }
+
+  if (field_type[field_type.size() - 1] != ' ') {
+    field_type += ' ';
+  }
+
+  std::string res = (field_num == 0 ? "" : ", ");
+  if (field_type == "bool " || field_type == "std::int32_t " || field_type == "std::int64_t " ||
+      field_type == "double ") {
+    res += field_type;
+  } else if (field_type == "UInt128 " || field_type == "UInt256 " || field_type == string_type + " ") {
+    res += field_type + "const &";
+  } else if (field_type.compare(0, 11, "std::vector") == 0 || field_type == bytes_type + " ") {
+    res += field_type + "&&";
+  } else if (field_type.compare(0, 10, "object_ptr") == 0) {
+    res += field_type + "&&";
+  } else {
+    assert(false && "unreachable");
+  }
+
+  return res + gen_field_name(a.name);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/generate/tl_writer_td.h b/libs/tdlib/td/td/generate/tl_writer_td.h
new file mode 100644
index 0000000000..b9f4d11b0a
--- /dev/null
+++ b/libs/tdlib/td/td/generate/tl_writer_td.h
@@ -0,0 +1,62 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/tl/tl_writer.h"
+
+#include <string>
+#include <vector>
+
+namespace td {
+
+class TD_TL_writer : public tl::TL_writer {
+  static const int MAX_ARITY = 0;
+
+  static const std::string base_type_class_names[MAX_ARITY + 1];
+  static const std::string base_tl_class_name;
+  static const std::string base_function_class_name;
+
+ protected:
+  const std::string string_type;
+  const std::string bytes_type;
+
+ public:
+  TD_TL_writer(const std::string &tl_name, const std::string &string_type, const std::string &bytes_type)
+      : TL_writer(tl_name), string_type(string_type), bytes_type(bytes_type) {
+  }
+
+  int get_max_arity() const override;
+
+  bool is_built_in_simple_type(const std::string &name) const override;
+  bool is_built_in_complex_type(const std::string &name) const override;
+  bool is_type_bare(const tl::tl_type *t) const override;
+  bool is_combinator_supported(const tl::tl_combinator *constructor) const override;
+
+  int get_storer_type(const tl::tl_combinator *t, const std::string &storer_name) const override;
+  Mode get_parser_mode(int type) const override;
+  Mode get_storer_mode(int type) const override;
+  std::vector<std::string> get_parsers() const override;
+  std::vector<std::string> get_storers() const override;
+
+  std::string gen_base_tl_class_name() const override;
+  std::string gen_base_type_class_name(int arity) const override;
+  std::string gen_base_function_class_name() const override;
+  std::string gen_class_name(std::string name) const override;
+  std::string gen_field_name(std::string name) const override;
+  std::string gen_var_name(const tl::var_description &desc) const override;
+  std::string gen_parameter_name(int index) const override;
+  std::string gen_type_name(const tl::tl_tree_type *tree_type) const override;
+  std::string gen_array_type_name(const tl::tl_tree_array *arr, const std::string &field_name) const override;
+  std::string gen_var_type_name() const override;
+
+  std::string gen_int_const(const tl::tl_tree *tree_c, const std::vector<tl::var_description> &vars) const override;
+
+  std::string gen_constructor_parameter(int field_num, const std::string &class_name, const tl::arg &a,
+                                        bool is_default) const override;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/AuthData.cpp b/libs/tdlib/td/td/mtproto/AuthData.cpp
new file mode 100644
index 0000000000..aa769d1d00
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/AuthData.cpp
@@ -0,0 +1,163 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/mtproto/AuthData.h"
+
+#include "td/utils/format.h"
+#include "td/utils/Random.h"
+#include "td/utils/Time.h"
+
+#include <algorithm>
+
+namespace td {
+namespace mtproto {
+
+Status MessageIdDuplicateChecker::check(int64 message_id) {
+  // In addition, the identifiers (msg_id) of the last N messages received from the other side must be stored, and if
+  // a message comes in with msg_id lower than all or equal to any of the stored values, that message is to be
+  // ignored. Otherwise, the new message msg_id is added to the set, and, if the number of stored msg_id values is
+  // greater than N, the oldest (i. e. the lowest) is forgotten.
+  if (saved_message_ids_.size() == MAX_SAVED_MESSAGE_IDS) {
+    auto oldest_message_id = *saved_message_ids_.begin();
+    if (message_id < oldest_message_id) {
+      return Status::Error(1, PSLICE() << "Ignore very old message_id " << tag("oldest message_id", oldest_message_id)
+                                       << tag("got message_id", message_id));
+    }
+  }
+  if (saved_message_ids_.count(message_id) != 0) {
+    return Status::Error(1, PSLICE() << "Ignore duplicated_message id " << tag("message_id", message_id));
+  }
+
+  saved_message_ids_.insert(message_id);
+  if (saved_message_ids_.size() > MAX_SAVED_MESSAGE_IDS) {
+    saved_message_ids_.erase(saved_message_ids_.begin());
+  }
+  return Status::OK();
+}
+
+AuthData::AuthData() {
+  server_salt_.salt = Random::secure_int64();
+  server_salt_.valid_since = -1e10;
+  server_salt_.valid_until = -1e10;
+}
+
+bool AuthData::is_ready(double now) {
+  if (!has_main_auth_key()) {
+    LOG(INFO) << "Need main auth key";
+    return false;
+  }
+  if (use_pfs() && !has_tmp_auth_key(now)) {
+    LOG(INFO) << "Need tmp auth key";
+    return false;
+  }
+  if (!has_salt(now)) {
+    LOG(INFO) << "no salt";
+    return false;
+  }
+  return true;
+}
+
+bool AuthData::update_server_time_difference(double diff) {
+  if (!server_time_difference_was_updated_) {
+    server_time_difference_was_updated_ = true;
+    LOG(DEBUG) << "UPDATE_SERVER_TIME_DIFFERENCE: " << server_time_difference_ << " -> " << diff;
+    server_time_difference_ = diff;
+  } else if (server_time_difference_ + 1e-4 < diff) {
+    LOG(DEBUG) << "UPDATE_SERVER_TIME_DIFFERENCE: " << server_time_difference_ << " -> " << diff;
+    server_time_difference_ = diff;
+  } else {
+    return false;
+  }
+  LOG(DEBUG) << "SERVER_TIME: " << format::as_hex(static_cast<int>(get_server_time(Time::now_cached())));
+  return true;
+}
+
+void AuthData::set_future_salts(const std::vector<ServerSalt> &salts, double now) {
+  if (salts.empty()) {
+    return;
+  }
+  future_salts_ = salts;
+  std::sort(future_salts_.begin(), future_salts_.end(),
+            [](const ServerSalt &a, const ServerSalt &b) { return a.valid_since > b.valid_since; });
+  update_salt(now);
+}
+
+std::vector<ServerSalt> AuthData::get_future_salts() const {
+  auto res = future_salts_;
+  res.push_back(server_salt_);
+  return res;
+}
+
+int64 AuthData::next_message_id(double now) {
+  double server_time = get_server_time(now);
+  int64 t = static_cast<int64>(server_time * (1ll << 32));
+
+  // randomize lower bits for clocks with low precision
+  // TODO(perf) do not do this for systems with good precision?..
+  auto rx = Random::secure_int32();
+  auto to_xor = rx & ((1 << 22) - 1);
+  auto to_mul = ((rx >> 22) & 1023) + 1;
+
+  t ^= to_xor;
+  auto result = t & -4;
+  if (last_message_id_ >= result) {
+    result = last_message_id_ + 8 * to_mul;
+  }
+  last_message_id_ = result;
+  return result;
+}
+
+bool AuthData::is_valid_outbound_msg_id(int64 id, double now) {
+  double server_time = get_server_time(now);
+  auto id_time = static_cast<double>(id / (1ll << 32));
+  return server_time - 300 / 2 < id_time && id_time < server_time + 60 / 2;
+}
+bool AuthData::is_valid_inbound_msg_id(int64 id, double now) {
+  double server_time = get_server_time(now);
+  auto id_time = static_cast<double>(id / (1ll << 32));
+  return server_time - 300 < id_time && id_time < server_time + 30;
+}
+
+Status AuthData::check_packet(int64 session_id, int64 message_id, double now, bool &time_difference_was_updated) {
+  // Client is to check that the session_id field in the decrypted message indeed equals to that of an active session
+  // created by the client.
+  if (get_session_id() != static_cast<uint64>(session_id)) {
+    return Status::Error(PSLICE() << "Got packet from different session " << tag("current session_id", get_session_id())
+                                  << tag("got session_id", session_id));
+  }
+
+  // Client must check that msg_id has even parity for messages from client to server, and odd parity for messages
+  // from server to client.
+  if ((message_id & 1) == 0) {
+    return Status::Error(PSLICE() << "Got invalid message_id " << tag("message_id", message_id));
+  }
+
+  TRY_STATUS(duplicate_checker_.check(message_id));
+
+  time_difference_was_updated = update_server_time_difference(static_cast<uint32>(message_id >> 32) - now);
+
+  // In addition, msg_id values that belong over 30 seconds in the future or over 300 seconds in the past are to be
+  // ignored (recall that msg_id approximately equals unixtime * 2^32). This is especially important for the server.
+  // The client would also find this useful (to protect from a replay attack), but only if it is certain of its time
+  // (for example, if its time has been synchronized with that of the server).
+  if (server_time_difference_was_updated_ && !is_valid_inbound_msg_id(message_id, now)) {
+    return Status::Error(PSLICE() << "Ignore message with too old or too new message_id "
+                                  << tag("message_id", message_id));
+  }
+
+  return Status::OK();
+}
+
+void AuthData::update_salt(double now) {
+  double server_time = get_server_time(now);
+  while (!future_salts_.empty() && (future_salts_.back().valid_since < server_time)) {
+    server_salt_ = future_salts_.back();
+    future_salts_.pop_back();
+  }
+}
+
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/AuthData.h b/libs/tdlib/td/td/mtproto/AuthData.h
new file mode 100644
index 0000000000..7293ffd1c6
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/AuthData.h
@@ -0,0 +1,277 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/mtproto/AuthKey.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <set>
+
+namespace td {
+namespace mtproto {
+
+struct ServerSalt {
+  int64 salt;
+  double valid_since;
+  double valid_until;
+};
+
+template <class StorerT>
+void store(const ServerSalt &salt, StorerT &storer) {
+  storer.template store_binary<int64>(salt.salt);
+  storer.template store_binary<double>(salt.valid_since);
+  storer.template store_binary<double>(salt.valid_until);
+}
+
+template <class ParserT>
+void parse(ServerSalt &salt, ParserT &parser) {
+  salt.salt = parser.fetch_long();
+  salt.valid_since = parser.fetch_double();
+  salt.valid_until = parser.fetch_double();
+}
+
+class MessageIdDuplicateChecker {
+ public:
+  Status check(int64 message_id);
+
+ private:
+  static constexpr size_t MAX_SAVED_MESSAGE_IDS = 1000;
+  std::set<int64> saved_message_ids_;
+};
+
+class AuthData {
+ public:
+  AuthData();
+  AuthData(const AuthData &) = delete;
+  AuthData &operator=(const AuthData &) = delete;
+  AuthData(AuthData &&) = delete;
+  AuthData &operator=(AuthData &&) = delete;
+  ~AuthData() = default;
+
+  bool is_ready(double now);
+
+  uint64 session_id_;
+  void set_main_auth_key(AuthKey auth_key) {
+    main_auth_key_ = std::move(auth_key);
+  }
+  const AuthKey &get_main_auth_key() const {
+    // CHECK(has_main_auth_key());
+    return main_auth_key_;
+  }
+  bool has_main_auth_key() const {
+    return !main_auth_key_.empty();
+  }
+  bool need_main_auth_key() const {
+    return !has_main_auth_key();
+  }
+
+  void set_tmp_auth_key(AuthKey auth_key) {
+    CHECK(!auth_key.empty());
+    tmp_auth_key_ = std::move(auth_key);
+  }
+  const AuthKey &get_tmp_auth_key() const {
+    // CHECK(has_tmp_auth_key());
+    return tmp_auth_key_;
+  }
+  bool was_tmp_auth_key() const {
+    return use_pfs() && !tmp_auth_key_.empty();
+  }
+  bool need_tmp_auth_key(double now) const {
+    if (!use_pfs()) {
+      return false;
+    }
+    if (tmp_auth_key_.empty()) {
+      return true;
+    }
+    if (now > tmp_auth_key_.expire_at() - 60 * 60 * 2 /*2 hours*/) {
+      return true;
+    }
+    if (!has_tmp_auth_key(now)) {
+      return true;
+    }
+    return false;
+  }
+  void drop_main_auth_key() {
+    main_auth_key_ = AuthKey();
+  }
+  void drop_tmp_auth_key() {
+    tmp_auth_key_ = AuthKey();
+  }
+  bool has_tmp_auth_key(double now) const {
+    if (!use_pfs()) {
+      return false;
+    }
+    if (tmp_auth_key_.empty()) {
+      return false;
+    }
+    if (now > tmp_auth_key_.expire_at() - 60 * 60 /*1 hour*/) {
+      return false;
+    }
+    return true;
+  }
+
+  const AuthKey &get_auth_key() const {
+    if (use_pfs()) {
+      return get_tmp_auth_key();
+    }
+    return get_main_auth_key();
+  }
+  bool has_auth_key(double now) const {
+    if (use_pfs()) {
+      return has_tmp_auth_key(now);
+    }
+    return has_main_auth_key();
+  }
+
+  bool get_auth_flag() const {
+    return main_auth_key_.auth_flag();
+  }
+  void set_auth_flag(bool auth_flag) {
+    main_auth_key_.set_auth_flag(auth_flag);
+    if (!auth_flag) {
+      tmp_auth_key_.set_auth_flag(auth_flag);
+    }
+  }
+
+  bool get_bind_flag() const {
+    return !use_pfs() || tmp_auth_key_.auth_flag();
+  }
+  void on_bind() {
+    CHECK(use_pfs());
+    tmp_auth_key_.set_auth_flag(true);
+  }
+
+  Slice header() {
+    if (use_pfs()) {
+      return tmp_auth_key_.need_header() ? Slice(header_) : Slice();
+    } else {
+      return main_auth_key_.need_header() ? Slice(header_) : Slice();
+    }
+  }
+  void set_header(std::string header) {
+    header_ = std::move(header);
+  }
+  void on_api_response() {
+    if (use_pfs()) {
+      if (tmp_auth_key_.auth_flag()) {
+        tmp_auth_key_.set_need_header(false);
+      }
+    } else {
+      if (main_auth_key_.auth_flag()) {
+        main_auth_key_.set_need_header(false);
+      }
+    }
+  }
+
+  uint64 get_session_id() const {
+    return session_id_;
+  }
+
+  double get_server_time(double now) const {
+    return server_time_difference_ + now;
+  }
+
+  double get_server_time_difference() const {
+    return server_time_difference_;
+  }
+
+  // diff == msg_id / 2^32 - now == old_server_now - now <= server_now - now
+  // server_time_difference >= max{diff}
+  bool update_server_time_difference(double diff);
+
+  void set_server_time_difference(double diff) {
+    server_time_difference_was_updated_ = false;
+    server_time_difference_ = diff;
+  }
+
+  uint64 get_server_salt(double now) {
+    update_salt(now);
+    return server_salt_.salt;
+  }
+
+  void set_server_salt(uint64 salt, double now) {
+    server_salt_.salt = salt;
+    double server_time = get_server_time(now);
+    server_salt_.valid_since = server_time;
+    server_salt_.valid_until = server_time + 60 * 10;
+    future_salts_.clear();
+  }
+
+  bool is_server_salt_valid(double now) {
+    return server_salt_.valid_until > get_server_time(now) + 60;
+  }
+
+  bool has_salt(double now) {
+    update_salt(now);
+    return is_server_salt_valid(now);
+  }
+
+  bool need_future_salts(double now) {
+    update_salt(now);
+    return future_salts_.empty() || !is_server_salt_valid(now);
+  }
+
+  void set_future_salts(const std::vector<ServerSalt> &salts, double now);
+
+  std::vector<ServerSalt> get_future_salts() const;
+
+  int64 next_message_id(double now);
+
+  bool is_valid_outbound_msg_id(int64 id, double now);
+
+  bool is_valid_inbound_msg_id(int64 id, double now);
+
+  Status check_packet(int64 session_id, int64 message_id, double now, bool &time_difference_was_updated);
+
+  Status check_update(int64 message_id) {
+    return updates_duplicate_checker_.check(message_id);
+  }
+
+  int32 next_seq_no(bool is_content_related) {
+    int32 res = seq_no_;
+    if (is_content_related) {
+      res |= 1;
+      seq_no_ += 2;
+    }
+    return res;
+  }
+
+  void clear_seq_no() {
+    seq_no_ = 0;
+  }
+
+  void set_use_pfs(bool use_pfs) {
+    use_pfs_ = use_pfs;
+  }
+  bool use_pfs() const {
+    return use_pfs_;
+  }
+
+ private:
+  bool use_pfs_ = true;
+  AuthKey main_auth_key_;
+  AuthKey tmp_auth_key_;
+  bool server_time_difference_was_updated_ = false;
+  double server_time_difference_ = 0;
+  ServerSalt server_salt_;
+  int64 last_message_id_ = 0;
+  int32 seq_no_ = 0;
+  std::string header_;
+
+  std::vector<ServerSalt> future_salts_;
+
+  MessageIdDuplicateChecker duplicate_checker_;
+  MessageIdDuplicateChecker updates_duplicate_checker_;
+
+  void update_salt(double now);
+};
+
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/AuthKey.h b/libs/tdlib/td/td/mtproto/AuthKey.h
new file mode 100644
index 0000000000..d71afc88e3
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/AuthKey.h
@@ -0,0 +1,90 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/Time.h"
+
+namespace td {
+namespace mtproto {
+class AuthKey {
+ public:
+  AuthKey() = default;
+  AuthKey(uint64 auth_key_id, string &&auth_key) : auth_key_id_(auth_key_id), auth_key_(auth_key) {
+  }
+
+  bool empty() const {
+    return auth_key_.empty();
+  }
+  const string &key() const {
+    return auth_key_;
+  }
+  uint64 id() const {
+    return auth_key_id_;
+  }
+  bool auth_flag() const {
+    return auth_flag_;
+  }
+  bool was_auth_flag() const {
+    return was_auth_flag_;
+  }
+  void set_auth_flag(bool new_auth_flag) {
+    if (new_auth_flag == false) {
+      clear();
+    } else {
+      was_auth_flag_ = true;
+    }
+    auth_flag_ = new_auth_flag;
+  }
+
+  bool need_header() const {
+    return need_header_;
+  }
+  void set_need_header(bool need_header) {
+    need_header_ = need_header;
+  }
+  double expire_at() const {
+    return expire_at_;
+  }
+  void set_expire_at(double expire_at) {
+    expire_at_ = expire_at;
+    // expire_at_ = Time::now() + 60 * 60 + 10 * 60;
+  }
+  void clear() {
+    auth_key_.clear();
+  }
+
+  enum { AUTH_FLAG = 1, WAS_AUTH_FLAG = 2 };
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    storer.store_binary(auth_key_id_);
+    storer.store_binary((auth_flag_ ? AUTH_FLAG : 0) | (was_auth_flag_ ? WAS_AUTH_FLAG : 0));
+    storer.store_string(auth_key_);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    auth_key_id_ = parser.fetch_long();
+    auto flags = parser.fetch_int();
+    auth_flag_ = (flags & AUTH_FLAG) != 0;
+    was_auth_flag_ = (flags & WAS_AUTH_FLAG) != 0 || auth_flag_;
+    auth_key_ = parser.template fetch_string<string>();
+    // just in case
+    need_header_ = true;
+  }
+
+ private:
+  uint64 auth_key_id_ = 0;
+  string auth_key_;
+  bool auth_flag_ = false;
+  bool was_auth_flag_ = false;
+  bool need_header_ = true;
+  double expire_at_ = 0;
+};
+
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/CryptoStorer.h b/libs/tdlib/td/td/mtproto/CryptoStorer.h
new file mode 100644
index 0000000000..08c1268493
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/CryptoStorer.h
@@ -0,0 +1,333 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/mtproto/AuthData.h"
+#include "td/mtproto/PacketStorer.h"
+#include "td/mtproto/utils.h"
+
+#include "td/mtproto/mtproto_api.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Time.h"
+
+namespace td {
+namespace mtproto {
+template <class Object, class ObjectStorer>
+class ObjectImpl {
+ public:
+  ObjectImpl(bool not_empty, Object &&object, AuthData *auth_data, bool need_ack = false)
+      : not_empty_(not_empty), object_(std::move(object)), object_storer_(object_) {
+    if (empty()) {
+      return;
+    }
+    message_id_ = auth_data->next_message_id(Time::now_cached());
+    seq_no_ = auth_data->next_seq_no(need_ack);
+  }
+  template <class T>
+  void do_store(T &storer) const {
+    if (empty()) {
+      return;
+    }
+    storer.store_binary(message_id_);
+    storer.store_binary(seq_no_);
+    storer.store_binary(static_cast<int32>(object_storer_.size()));
+    storer.store_storer(object_storer_);
+  }
+  bool not_empty() const {
+    return not_empty_;
+  }
+  bool empty() const {
+    return !not_empty_;
+  }
+  uint64 get_message_id() const {
+    return message_id_;
+  }
+
+ private:
+  bool not_empty_;
+  Object object_;
+  ObjectStorer object_storer_;
+  uint64 message_id_;
+  int32 seq_no_;
+};
+
+using AckImpl = ObjectImpl<mtproto_api::msgs_ack, TLObjectStorer<mtproto_api::msgs_ack>>;
+using PingImpl = ObjectImpl<mtproto_api::ping_delay_disconnect, TLStorer<mtproto_api::ping_delay_disconnect>>;
+using HttpWaitImpl = ObjectImpl<mtproto_api::http_wait, TLStorer<mtproto_api::http_wait>>;
+using GetFutureSaltsImpl = ObjectImpl<mtproto_api::get_future_salts, TLStorer<mtproto_api::get_future_salts>>;
+using ResendImpl = ObjectImpl<mtproto_api::msg_resend_req, TLObjectStorer<mtproto_api::msg_resend_req>>;
+using CancelImpl = ObjectImpl<mtproto_api::rpc_drop_answer, TLStorer<mtproto_api::rpc_drop_answer>>;
+using GetInfoImpl = ObjectImpl<mtproto_api::msgs_state_req, TLObjectStorer<mtproto_api::msgs_state_req>>;
+
+class CancelVectorImpl {
+ public:
+  CancelVectorImpl(bool not_empty, const vector<int64> &to_cancel, AuthData *auth_data, bool need_ack) {
+    storers_.reserve(to_cancel.size());
+    for (auto &request_id : to_cancel) {
+      storers_.emplace_back(true, mtproto_api::rpc_drop_answer(request_id), auth_data, true);
+    }
+  }
+
+  template <class T>
+  void do_store(T &storer) const {
+    for (auto &s : storers_) {
+      storer.store_storer(s);
+    }
+  }
+  bool not_empty() const {
+    return !storers_.empty();
+  }
+  uint64 get_message_id() const {
+    CHECK(storers_.size() == 1);
+    return storers_[0].get_message_id();
+  }
+
+ private:
+  vector<PacketStorer<CancelImpl>> storers_;
+};
+
+class QueryImpl {
+ public:
+  QueryImpl(const Query &query, Slice header) : query_(query), header_(header) {
+  }
+
+  template <class T>
+  void do_store(T &storer) const {
+    storer.store_binary(query_.message_id);
+    storer.store_binary(query_.seq_no);
+    Slice header = this->header_;
+    Slice invoke_header = Slice();
+
+// TODO(refactor):
+// invokeAfterMsg#cb9f372d {X:Type} msg_id:long query:!X = X;
+// This code makes me very sad.
+// InvokeAfterMsg is not even in mtproto_api. It is in telegram_api.
+#pragma pack(push, 4)
+    struct {
+      uint32 constructor_id;
+      uint64 invoke_after_id;
+    } invoke_data;
+#pragma pack(pop)
+    if (query_.invoke_after_id != 0) {
+      invoke_data.constructor_id = 0xcb9f372d;
+      invoke_data.invoke_after_id = query_.invoke_after_id;
+      invoke_header = Slice(reinterpret_cast<const uint8 *>(&invoke_data), sizeof(invoke_data));
+    }
+
+    Slice data = query_.packet.as_slice();
+    mtproto_api::gzip_packed packed(data);
+    auto plain_storer = create_storer(data);
+    auto gzip_storer = create_storer(packed);
+    const Storer &data_storer =
+        query_.gzip_flag ? static_cast<const Storer &>(gzip_storer) : static_cast<const Storer &>(plain_storer);
+    auto invoke_header_storer = create_storer(invoke_header);
+    auto header_storer = create_storer(header);
+    auto suff_storer = create_storer(invoke_header_storer, data_storer);
+    auto all_storer = create_storer(header_storer, suff_storer);
+
+    storer.store_binary(static_cast<uint32>(all_storer.size()));
+    storer.store_storer(all_storer);
+  }
+
+ private:
+  const Query &query_;
+  Slice header_;
+};
+
+class QueryVectorImpl {
+ public:
+  QueryVectorImpl(const vector<Query> &to_send, Slice header) : to_send_(to_send), header_(header) {
+  }
+
+  template <class T>
+  void do_store(T &storer) const {
+    if (to_send_.empty()) {
+      return;
+    }
+    for (auto &query : to_send_) {
+      storer.store_storer(PacketStorer<QueryImpl>(query, header_));
+    }
+  }
+
+ private:
+  const vector<Query> &to_send_;
+  Slice header_;
+};
+
+class ContainerImpl {
+ public:
+  ContainerImpl(int32 cnt, Storer &storer) : cnt_(cnt), storer_(storer) {
+  }
+
+  template <class T>
+  void do_store(T &storer) const {
+    storer.store_binary(mtproto_api::msg_container::ID);
+    storer.store_binary(cnt_);
+    storer.store_storer(storer_);
+  }
+
+ private:
+  int32 cnt_;
+  Storer &storer_;
+};
+
+class CryptoImpl {
+ public:
+  CryptoImpl(const vector<Query> &to_send, Slice header, vector<int64> &&to_ack, int64 ping_id, int ping_timeout,
+             int max_delay, int max_after, int max_wait, int future_salt_n, vector<int64> get_info,
+             vector<int64> resend, vector<int64> cancel, AuthData *auth_data, uint64 *container_id, uint64 *get_info_id,
+             uint64 *resend_id, uint64 *ping_message_id, uint64 *parent_message_id)
+      : query_storer_(to_send, header)
+      , ack_empty_(to_ack.empty())
+      , ack_storer_(!ack_empty_, mtproto_api::msgs_ack(std::move(to_ack)), auth_data)
+      , ping_storer_(ping_id != 0, mtproto_api::ping_delay_disconnect(ping_id, ping_timeout), auth_data)
+      , http_wait_storer_(max_delay >= 0, mtproto_api::http_wait(max_delay, max_after, max_wait), auth_data)
+      , get_future_salts_storer_(future_salt_n > 0, mtproto_api::get_future_salts(future_salt_n), auth_data)
+      , get_info_not_empty_(!get_info.empty())
+      , get_info_storer_(get_info_not_empty_, mtproto_api::msgs_state_req(std::move(get_info)), auth_data, true)
+      , resend_not_empty_(!resend.empty())
+      , resend_storer_(resend_not_empty_, mtproto_api::msg_resend_req(std::move(resend)), auth_data, true)
+      , cancel_not_empty_(!cancel.empty())
+      , cancel_cnt_(static_cast<int32>(cancel.size()))
+      , cancel_storer_(cancel_not_empty_, std::move(cancel), auth_data, true)
+      , tmp_storer_(query_storer_, ack_storer_)
+      , tmp2_storer_(tmp_storer_, http_wait_storer_)
+      , tmp3_storer_(tmp2_storer_, get_future_salts_storer_)
+      , tmp4_storer_(tmp3_storer_, get_info_storer_)
+      , tmp5_storer_(tmp4_storer_, resend_storer_)
+      , tmp6_storer_(tmp5_storer_, cancel_storer_)
+      , concat_storer_(tmp6_storer_, ping_storer_)
+      , cnt_(static_cast<int32>(to_send.size()) + ack_storer_.not_empty() + ping_storer_.not_empty() +
+             http_wait_storer_.not_empty() + get_future_salts_storer_.not_empty() + get_info_storer_.not_empty() +
+             resend_storer_.not_empty() + cancel_cnt_)
+      , container_storer_(cnt_, concat_storer_) {
+    CHECK(cnt_ != 0);
+    if (get_info_storer_.not_empty() && get_info_id) {
+      *get_info_id = get_info_storer_.get_message_id();
+    }
+    if (resend_storer_.not_empty() && resend_id) {
+      *resend_id = resend_storer_.get_message_id();
+    }
+    if (ping_storer_.not_empty() && ping_message_id) {
+      *ping_message_id = ping_storer_.get_message_id();
+    }
+
+    if (cnt_ > 1 ||
+        (!to_send.empty() && !auth_data->is_valid_outbound_msg_id(to_send[0].message_id, Time::now_cached()))) {
+      type_ = Mixed;
+      message_id_ = auth_data->next_message_id(Time::now_cached());
+      seq_no_ = auth_data->next_seq_no(false);
+
+      *container_id = message_id_;
+      *parent_message_id = message_id_;
+    } else if (!to_send.empty()) {
+      CHECK(to_send.size() == 1u);
+      type_ = OnlyQuery;
+      *parent_message_id = to_send[0].message_id;
+    } else if (ack_storer_.not_empty()) {
+      type_ = OnlyAck;
+      *parent_message_id = ack_storer_.get_message_id();
+    } else if (ping_storer_.not_empty()) {
+      type_ = OnlyPing;
+      *parent_message_id = ping_storer_.get_message_id();
+    } else if (http_wait_storer_.not_empty()) {
+      type_ = OnlyHttpWait;
+      *parent_message_id = http_wait_storer_.get_message_id();
+    } else if (get_future_salts_storer_.not_empty()) {
+      type_ = OnlyGetFutureSalts;
+      *parent_message_id = get_future_salts_storer_.get_message_id();
+    } else if (get_info_storer_.not_empty()) {
+      type_ = OnlyGetInfo;
+      *parent_message_id = get_info_storer_.get_message_id();
+    } else if (resend_storer_.not_empty()) {
+      type_ = OnlyResend;
+      *parent_message_id = resend_storer_.get_message_id();
+    } else if (cancel_storer_.not_empty()) {
+      type_ = OnlyCancel;
+      *parent_message_id = cancel_storer_.get_message_id();
+    } else {
+      UNREACHABLE();
+    }
+  }
+
+  template <class T>
+  void do_store(T &storer) const {
+    switch (type_) {
+      case OnlyAck:
+        return storer.store_storer(ack_storer_);
+
+      case OnlyQuery:
+        return storer.store_storer(query_storer_);
+
+      case OnlyPing:
+        return storer.store_storer(ping_storer_);
+
+      case OnlyHttpWait:
+        return storer.store_storer(http_wait_storer_);
+
+      case OnlyGetFutureSalts:
+        return storer.store_storer(get_future_salts_storer_);
+
+      case OnlyResend:
+        return storer.store_storer(resend_storer_);
+
+      case OnlyCancel:
+        return storer.store_storer(cancel_storer_);
+
+      case OnlyGetInfo:
+        return storer.store_storer(get_info_storer_);
+
+      default:
+        storer.store_binary(message_id_);
+        storer.store_binary(seq_no_);
+        storer.store_binary(static_cast<int32>(container_storer_.size()));
+        storer.store_storer(container_storer_);
+    }
+  }
+
+ private:
+  PacketStorer<QueryVectorImpl> query_storer_;
+  bool ack_empty_;
+  PacketStorer<AckImpl> ack_storer_;
+  PacketStorer<PingImpl> ping_storer_;
+  PacketStorer<HttpWaitImpl> http_wait_storer_;
+  PacketStorer<GetFutureSaltsImpl> get_future_salts_storer_;
+  bool get_info_not_empty_;
+  PacketStorer<GetInfoImpl> get_info_storer_;
+  bool resend_not_empty_;
+  PacketStorer<ResendImpl> resend_storer_;
+  bool cancel_not_empty_;
+  int32 cancel_cnt_;
+  PacketStorer<CancelVectorImpl> cancel_storer_;
+  ConcatStorer tmp_storer_;
+  ConcatStorer tmp2_storer_;
+  ConcatStorer tmp3_storer_;
+  ConcatStorer tmp4_storer_;
+  ConcatStorer tmp5_storer_;
+  ConcatStorer tmp6_storer_;
+  ConcatStorer concat_storer_;
+  int32 cnt_;
+  PacketStorer<ContainerImpl> container_storer_;
+  enum Type {
+    OnlyQuery,
+    OnlyAck,
+    OnlyPing,
+    OnlyHttpWait,
+    OnlyGetFutureSalts,
+    OnlyResend,
+    OnlyCancel,
+    OnlyGetInfo,
+    Mixed
+  };
+  Type type_;
+  uint64 message_id_;
+  int32 seq_no_;
+};
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/Handshake.cpp b/libs/tdlib/td/td/mtproto/Handshake.cpp
new file mode 100644
index 0000000000..e5ed75994a
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/Handshake.cpp
@@ -0,0 +1,301 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/mtproto/Handshake.h"
+
+#include "td/mtproto/utils.h"
+
+#include "td/mtproto/mtproto_api.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/crypto.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/Random.h"
+#include "td/utils/Status.h"
+#include "td/utils/Time.h"
+#include "td/utils/tl_parsers.h"
+#include "td/utils/tl_storers.h"
+
+namespace td {
+namespace mtproto {
+
+void AuthKeyHandshake::clear() {
+  last_query_ = BufferSlice();
+  state_ = Start;
+}
+
+bool AuthKeyHandshake::is_ready_for_start() {
+  return state_ == Start;
+}
+bool AuthKeyHandshake::is_ready_for_message(const UInt128 &message_nonce) {
+  return state_ != Finish && state_ != Start && nonce == message_nonce;
+}
+bool AuthKeyHandshake::is_ready_for_finish() {
+  return state_ == Finish;
+}
+void AuthKeyHandshake::on_finish() {
+  clear();
+}
+
+template <class DataT>
+Result<size_t> AuthKeyHandshake::fill_data_with_hash(uint8 *data_with_hash, const DataT &data) {
+  // data_with_hash := SHA1(data) + data + (any random bytes); such that the length equal 255 bytes;
+  uint8 *data_ptr = data_with_hash + 20;
+  size_t data_size = tl_calc_length(data);
+  if (data_size + 20 + 4 > 255) {
+    return Status::Error("Too big data");
+  }
+  as<int32>(data_ptr) = data.get_id();
+  tl_store_unsafe(data, data_ptr + 4);
+  sha1(Slice(data_ptr, data_size + 4), data_with_hash);
+  return data_size + 20 + 4;
+}
+
+Status AuthKeyHandshake::on_res_pq(Slice message, Callback *connection, PublicRsaKeyInterface *public_rsa_key) {
+  TRY_RESULT(res_pq, fetch_result<mtproto_api::req_pq_multi>(message));
+  if (res_pq->nonce_ != nonce) {
+    return Status::Error("Nonce mismatch");
+  }
+
+  server_nonce = res_pq->server_nonce_;
+
+  auto r_rsa = public_rsa_key->get_rsa(res_pq->server_public_key_fingerprints_);
+  if (r_rsa.is_error()) {
+    public_rsa_key->drop_keys();
+    return r_rsa.move_as_error();
+  }
+  int64 rsa_fingerprint = r_rsa.ok().second;
+  RSA rsa = std::move(r_rsa.ok_ref().first);
+
+  string p, q;
+  if (pq_factorize(res_pq->pq_, &p, &q) == -1) {
+    return Status::Error("Failed to factorize");
+  }
+
+  Random::secure_bytes(new_nonce.raw, sizeof(new_nonce));
+
+  alignas(8) uint8 data_with_hash[255];
+  Result<size_t> r_data_size = 0;
+  switch (mode_) {
+    case Mode::Main:
+      r_data_size = fill_data_with_hash(data_with_hash,
+                                        mtproto_api::p_q_inner_data(res_pq->pq_, p, q, nonce, server_nonce, new_nonce));
+      break;
+    case Mode::Temp:
+      r_data_size = fill_data_with_hash(
+          data_with_hash,
+          mtproto_api::p_q_inner_data_temp(res_pq->pq_, p, q, nonce, server_nonce, new_nonce, expire_in_));
+      expire_at_ = Time::now() + expire_in_;
+      break;
+    case Mode::Unknown:
+    default:
+      UNREACHABLE();
+      r_data_size = Status::Error(500, "Unreachable");
+  }
+  if (r_data_size.is_error()) {
+    return r_data_size.move_as_error();
+  }
+  size_t size = r_data_size.ok();
+
+  // encrypted_data := RSA (data_with_hash, server_public_key); a 255-byte long number (big endian)
+  //   is raised to the requisite power over the requisite modulus, and the result is stored as a 256-byte number.
+  string encrypted_data(256, 0);
+  rsa.encrypt(data_with_hash, size, reinterpret_cast<unsigned char *>(&encrypted_data[0]));
+
+  // req_DH_params#d712e4be nonce:int128 server_nonce:int128 p:string q:string public_key_fingerprint:long
+  // encrypted_data:string = Server_DH_Params
+  mtproto_api::req_DH_params req_dh_params(nonce, server_nonce, p, q, rsa_fingerprint, std::move(encrypted_data));
+
+  send(connection, create_storer(req_dh_params));
+  state_ = ServerDHParams;
+  return Status::OK();
+}
+
+Status AuthKeyHandshake::on_server_dh_params(Slice message, Callback *connection, DhCallback *dh_callback) {
+  TRY_RESULT(server_dh_params, fetch_result<mtproto_api::req_DH_params>(message));
+  switch (server_dh_params->get_id()) {
+    case mtproto_api::server_DH_params_ok::ID:
+      break;
+    case mtproto_api::server_DH_params_fail::ID:
+      return Status::Error("Server dh params fail");
+    default:
+      return Status::Error("Unknown result");
+  }
+
+  auto dh_params = move_tl_object_as<mtproto_api::server_DH_params_ok>(server_dh_params);
+
+  // server_DH_params_ok#d0e8075c nonce:int128 server_nonce:int128 encrypted_answer:string = Server_DH_Params;
+  if (dh_params->nonce_ != nonce) {
+    return Status::Error("Nonce mismatch");
+  }
+  if (dh_params->server_nonce_ != server_nonce) {
+    return Status::Error("Server nonce mismatch");
+  }
+  if (dh_params->encrypted_answer_.size() & 15) {
+    return Status::Error("Bad padding for encrypted part");
+  }
+
+  tmp_KDF(server_nonce, new_nonce, &tmp_aes_key, &tmp_aes_iv);
+  auto save_tmp_aes_iv = tmp_aes_iv;
+  // encrypted_answer := AES256_ige_encrypt (answer_with_hash, tmp_aes_key, tmp_aes_iv);
+  MutableSlice answer(const_cast<char *>(dh_params->encrypted_answer_.begin()), dh_params->encrypted_answer_.size());
+  aes_ige_decrypt(tmp_aes_key, &tmp_aes_iv, answer, answer);
+  tmp_aes_iv = save_tmp_aes_iv;
+
+  // answer_with_hash := SHA1(answer) + answer + (0-15 random bytes)
+  TlParser answer_parser(answer);
+  UInt<160> answer_sha1 = answer_parser.fetch_binary<UInt<160>>();
+  int32 id = answer_parser.fetch_int();
+  if (id != mtproto_api::server_DH_inner_data::ID) {
+    return Status::Error("Failed to fetch server_DH_inner_data");
+  }
+  mtproto_api::server_DH_inner_data dh_inner_data(answer_parser);
+  if (answer_parser.get_error() != nullptr) {
+    return Status::Error("Failed to fetch server_DH_inner_data");
+  }
+
+  size_t pad = answer_parser.get_left_len();
+  if (pad >= 16) {
+    return Status::Error("Too much pad");
+  }
+
+  size_t dh_inner_data_size = answer.size() - pad - 20;
+  UInt<160> answer_real_sha1;
+  sha1(Slice(answer.ubegin() + 20, dh_inner_data_size), answer_real_sha1.raw);
+  if (answer_sha1 != answer_real_sha1) {
+    return Status::Error("SHA1 mismatch");
+  }
+
+  // server_DH_inner_data#b5890dba nonce:int128 server_nonce:int128 g:int dh_prime:string g_a:string server_time:int =
+  // Server_DH_inner_data;
+  if (dh_inner_data.nonce_ != nonce) {
+    return Status::Error("Nonce mismatch");
+  }
+  if (dh_inner_data.server_nonce_ != server_nonce) {
+    return Status::Error("Server nonce mismatch");
+  }
+
+  server_time_diff = dh_inner_data.server_time_ - Time::now();
+
+  string g_b;
+  string auth_key_str;
+  TRY_STATUS(
+      dh_handshake(dh_inner_data.g_, dh_inner_data.dh_prime_, dh_inner_data.g_a_, &g_b, &auth_key_str, dh_callback));
+
+  mtproto_api::client_DH_inner_data data(nonce, server_nonce, 0, g_b);
+  size_t data_size = 4 + tl_calc_length(data);
+  size_t encrypted_data_size = 20 + data_size;
+  size_t encrypted_data_size_with_pad = (encrypted_data_size + 15) & -16;
+  string encrypted_data_str(encrypted_data_size_with_pad, 0);
+  MutableSlice encrypted_data = encrypted_data_str;
+  as<int32>(encrypted_data.begin() + 20) = data.get_id();
+  tl_store_unsafe(data, encrypted_data.begin() + 20 + 4);
+  sha1(Slice(encrypted_data.ubegin() + 20, data_size), encrypted_data.ubegin());
+  Random::secure_bytes(encrypted_data.ubegin() + encrypted_data_size,
+                       encrypted_data_size_with_pad - encrypted_data_size);
+  tmp_KDF(server_nonce, new_nonce, &tmp_aes_key, &tmp_aes_iv);
+  aes_ige_encrypt(tmp_aes_key, &tmp_aes_iv, encrypted_data, encrypted_data);
+
+  mtproto_api::set_client_DH_params set_client_dh_params(nonce, server_nonce, std::move(encrypted_data_str));
+  send(connection, create_storer(set_client_dh_params));
+
+  auth_key = AuthKey(dh_auth_key_id(auth_key_str), std::move(auth_key_str));
+  if (mode_ == Mode::Temp) {
+    auth_key.set_expire_at(expire_at_);
+  }
+
+  server_salt = as<int64>(new_nonce.raw) ^ as<int64>(server_nonce.raw);
+
+  state_ = DHGenResponse;
+  return Status::OK();
+}
+
+Status AuthKeyHandshake::on_dh_gen_response(Slice message, Callback *connection) {
+  TRY_RESULT(answer, fetch_result<mtproto_api::set_client_DH_params>(message));
+  switch (answer->get_id()) {
+    case mtproto_api::dh_gen_ok::ID:
+      state_ = Finish;
+      break;
+    case mtproto_api::dh_gen_fail::ID:
+      return Status::Error("DhGenFail");
+    case mtproto_api::dh_gen_retry::ID:
+      return Status::Error("DhGenRetry");
+    default:
+      return Status::Error("Unknown set_client_DH_params response");
+  }
+  return Status::OK();
+}
+void AuthKeyHandshake::send(Callback *connection, const Storer &storer) {
+  auto writer = BufferWriter{storer.size(), 0, 0};
+  storer.store(writer.as_slice().ubegin());
+  last_query_ = writer.as_buffer_slice();
+  return do_send(connection, create_storer(last_query_.as_slice()));
+}
+void AuthKeyHandshake::do_send(Callback *connection, const Storer &storer) {
+  return connection->send_no_crypto(storer);
+}
+
+Status AuthKeyHandshake::start_main(Callback *connection) {
+  mode_ = Mode::Main;
+  return on_start(connection);
+}
+
+Status AuthKeyHandshake::start_tmp(Callback *connection, int32 expire_in) {
+  mode_ = Mode::Temp;
+  expire_in_ = expire_in;
+  return on_start(connection);
+}
+
+void AuthKeyHandshake::resume(Callback *connection) {
+  if (state_ == Start) {
+    return on_start(connection).ignore();
+  }
+  if (state_ == Finish) {
+    LOG(ERROR) << "State is Finish during resume. UNREACHABLE";
+    return clear();
+  }
+  if (last_query_.empty()) {
+    LOG(ERROR) << "Last query empty! UNREACHABLE " << state_;
+    return clear();
+  }
+  LOG(INFO) << "RESUME";
+  do_send(connection, create_storer(last_query_.as_slice()));
+}
+
+Status AuthKeyHandshake::on_start(Callback *connection) {
+  if (state_ != Start) {
+    clear();
+    return Status::Error(PSLICE() << "on_start called after start " << tag("state", state_));
+  }
+  Random::secure_bytes(nonce.raw, sizeof(nonce));
+  send(connection, create_storer(mtproto_api::req_pq_multi(nonce)));
+  state_ = ResPQ;
+
+  return Status::OK();
+}
+
+Status AuthKeyHandshake::on_message(Slice message, Callback *connection, Context *context) {
+  Status status = [&] {
+    switch (state_) {
+      case ResPQ:
+        return on_res_pq(message, connection, context->get_public_rsa_key_interface());
+      case ServerDHParams:
+        return on_server_dh_params(message, connection, context->get_dh_callback());
+      case DHGenResponse:
+        return on_dh_gen_response(message, connection);
+      default:
+        UNREACHABLE();
+    }
+  }();
+  if (status.is_error()) {
+    clear();
+  }
+  return status;
+}
+
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/Handshake.h b/libs/tdlib/td/td/mtproto/Handshake.h
new file mode 100644
index 0000000000..8c7ae7baac
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/Handshake.h
@@ -0,0 +1,102 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/mtproto/AuthKey.h"
+#include "td/mtproto/crypto.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/int_types.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+namespace td {
+class Storer;
+namespace mtproto {
+class AuthKeyHandshakeContext {
+ public:
+  virtual ~AuthKeyHandshakeContext() = default;
+  virtual DhCallback *get_dh_callback() = 0;
+  virtual PublicRsaKeyInterface *get_public_rsa_key_interface() = 0;
+};
+class AuthKeyHandshake {
+ public:
+  class Callback {
+   public:
+    Callback() = default;
+    Callback(const Callback &) = delete;
+    Callback &operator=(const Callback &) = delete;
+    virtual ~Callback() = default;
+    virtual void send_no_crypto(const Storer &storer) = 0;
+  };
+  using Context = AuthKeyHandshakeContext;
+  enum class Mode { Unknown, Main, Temp };
+  AuthKey auth_key;
+  double server_time_diff = 0;
+  uint64 server_salt = 0;
+
+  bool is_ready_for_start();
+  Status start_main(Callback *connection) TD_WARN_UNUSED_RESULT;
+  Status start_tmp(Callback *connection, int32 expire_in) TD_WARN_UNUSED_RESULT;
+
+  bool is_ready_for_message(const UInt128 &message_nonce);
+
+  bool is_ready_for_finish();
+  void on_finish();
+
+  explicit AuthKeyHandshake(int32 expire_in = 0) {
+    if (expire_in == 0) {
+      mode_ = Mode::Main;
+    } else {
+      mode_ = Mode::Temp;
+      expire_in_ = expire_in;
+    }
+  }
+  void init_main() {
+    clear();
+    mode_ = Mode::Main;
+  }
+  void init_temp(int32 expire_in) {
+    clear();
+    mode_ = Mode::Temp;
+    expire_in_ = expire_in;
+  }
+  void resume(Callback *connection);
+  Status on_message(Slice message, Callback *connection, Context *context) TD_WARN_UNUSED_RESULT;
+  bool is_ready() {
+    return is_ready_for_finish();
+  }
+  void clear();
+
+ private:
+  using State = enum { Start, ResPQ, ServerDHParams, DHGenResponse, Finish };
+  State state_ = Start;
+  Mode mode_ = Mode::Unknown;
+  int32 expire_in_;
+  double expire_at_ = 0;
+
+  UInt128 nonce;
+  UInt128 server_nonce;
+  UInt256 new_nonce;
+  UInt256 tmp_aes_key;
+  UInt256 tmp_aes_iv;
+
+  BufferSlice last_query_;
+
+  template <class DataT>
+  Result<size_t> fill_data_with_hash(uint8 *data_with_hash, const DataT &data) TD_WARN_UNUSED_RESULT;
+
+  void send(Callback *connection, const Storer &storer);
+  void do_send(Callback *connection, const Storer &storer);
+
+  Status on_start(Callback *connection) TD_WARN_UNUSED_RESULT;
+  Status on_res_pq(Slice message, Callback *connection, PublicRsaKeyInterface *public_rsa_key) TD_WARN_UNUSED_RESULT;
+  Status on_server_dh_params(Slice message, Callback *connection, DhCallback *dh_callback) TD_WARN_UNUSED_RESULT;
+  Status on_dh_gen_response(Slice message, Callback *connection) TD_WARN_UNUSED_RESULT;
+};
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/HandshakeActor.cpp b/libs/tdlib/td/td/mtproto/HandshakeActor.cpp
new file mode 100644
index 0000000000..6eb888cd76
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/HandshakeActor.cpp
@@ -0,0 +1,93 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/mtproto/HandshakeActor.h"
+#include "td/mtproto/HandshakeConnection.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/Status.h"
+
+namespace td {
+namespace mtproto {
+HandshakeActor::HandshakeActor(std::unique_ptr<AuthKeyHandshake> handshake,
+                               std::unique_ptr<RawConnection> raw_connection,
+                               std::unique_ptr<AuthKeyHandshakeContext> context, double timeout,
+                               Promise<std::unique_ptr<RawConnection>> raw_connection_promise,
+                               Promise<std::unique_ptr<AuthKeyHandshake>> handshake_promise)
+    : handshake_(std::move(handshake))
+    , connection_(
+          std::make_unique<HandshakeConnection>(std::move(raw_connection), handshake_.get(), std::move(context)))
+    , timeout_(timeout)
+    , raw_connection_promise_(std::move(raw_connection_promise))
+    , handshake_promise_(std::move(handshake_promise)) {
+}
+
+void HandshakeActor::close() {
+  finish(Status::Error("Cancelled"));
+  stop();
+}
+
+void HandshakeActor::start_up() {
+  connection_->get_pollable().set_observer(this);
+  subscribe(connection_->get_pollable());
+  set_timeout_in(timeout_);
+  yield();
+}
+
+void HandshakeActor::loop() {
+  auto status = connection_->flush();
+  if (status.is_error()) {
+    finish(std::move(status));
+    return stop();
+  }
+  if (handshake_->is_ready_for_finish()) {
+    finish(Status::OK());
+    return stop();
+  }
+}
+
+void HandshakeActor::return_connection(Status status) {
+  auto raw_connection = connection_->move_as_raw_connection();
+  if (!raw_connection) {
+    CHECK(!raw_connection_promise_);
+    return;
+  }
+  if (status.is_error()) {
+    status = Status::Error(status.code(), PSLICE() << status.message() << " : " << raw_connection->debug_str_);
+  }
+  unsubscribe(raw_connection->get_pollable());
+  raw_connection->get_pollable().set_observer(nullptr);
+  if (raw_connection_promise_) {
+    if (status.is_error()) {
+      if (raw_connection->stats_callback()) {
+        raw_connection->stats_callback()->on_error();
+      }
+      raw_connection->close();
+      raw_connection_promise_.set_error(std::move(status));
+    } else {
+      if (raw_connection->stats_callback()) {
+        raw_connection->stats_callback()->on_pong();
+      }
+      raw_connection_promise_.set_value(std::move(raw_connection));
+    }
+  } else {
+    if (raw_connection->stats_callback()) {
+      raw_connection->stats_callback()->on_error();
+    }
+    raw_connection->close();
+  }
+}
+
+void HandshakeActor::return_handshake() {
+  if (!handshake_promise_) {
+    CHECK(!handshake_);
+    return;
+  }
+  handshake_promise_.set_value(std::move(handshake_));
+}
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/HandshakeActor.h b/libs/tdlib/td/td/mtproto/HandshakeActor.h
new file mode 100644
index 0000000000..296dae62ca
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/HandshakeActor.h
@@ -0,0 +1,58 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/utils/Status.h"
+
+namespace td {
+class DhCallback;
+namespace mtproto {
+class AuthKeyHandshake;
+class AuthKeyHandshakeContext;
+class RawConnection;
+class HandshakeConnection;
+// Has Raw connection. Generates new auth key. And returns it and raw_connection. Or error...
+class HandshakeActor : public Actor {
+ public:
+  HandshakeActor(std::unique_ptr<AuthKeyHandshake> handshake, std::unique_ptr<RawConnection> raw_connection,
+                 std::unique_ptr<AuthKeyHandshakeContext> context, double timeout,
+                 Promise<std::unique_ptr<RawConnection>> raw_connection_promise,
+                 Promise<std::unique_ptr<AuthKeyHandshake>> handshake_promise);
+  void close();
+
+ private:
+  std::unique_ptr<AuthKeyHandshake> handshake_;
+  std::unique_ptr<HandshakeConnection> connection_;
+  double timeout_;
+
+  Promise<std::unique_ptr<RawConnection>> raw_connection_promise_;
+  Promise<std::unique_ptr<AuthKeyHandshake>> handshake_promise_;
+
+  void start_up() override;
+  void tear_down() override {
+    finish(Status::OK());
+  }
+  void timeout_expired() override {
+    finish(Status::Error("Timeout expired"));
+    stop();
+  }
+  void loop() override;
+
+  void finish(Status status) {
+    // NB: order may be important for parent
+    return_connection(std::move(status));
+    return_handshake();
+  }
+
+  void return_connection(Status status);
+  void return_handshake();
+};
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/HandshakeConnection.h b/libs/tdlib/td/td/mtproto/HandshakeConnection.h
new file mode 100644
index 0000000000..5c9341ddc9
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/HandshakeConnection.h
@@ -0,0 +1,81 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/mtproto/AuthKey.h"
+#include "td/mtproto/Handshake.h"
+#include "td/mtproto/NoCryptoStorer.h"
+#include "td/mtproto/RawConnection.h"
+#include "td/mtproto/Transport.h"
+#include "td/mtproto/utils.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/Status.h"
+
+namespace td {
+namespace mtproto {
+class HandshakeConnection
+    : private RawConnection::Callback
+    , private AuthKeyHandshake::Callback {
+ public:
+  HandshakeConnection(std::unique_ptr<RawConnection> raw_connection, AuthKeyHandshake *handshake,
+                      std::unique_ptr<AuthKeyHandshakeContext> context)
+      : raw_connection_(std::move(raw_connection)), handshake_(handshake), context_(std::move(context)) {
+    handshake_->resume(this);
+  }
+
+  Fd &get_pollable() {
+    return raw_connection_->get_pollable();
+  }
+
+  std::unique_ptr<RawConnection> move_as_raw_connection() {
+    return std::move(raw_connection_);
+  }
+
+  void close() {
+    raw_connection_->close();
+  }
+
+  Status flush() {
+    auto status = raw_connection_->flush(AuthKey(), *this);
+    if (status.code() == -404) {
+      LOG(WARNING) << "Clear handshake " << tag("error", status);
+      handshake_->clear();
+    }
+    return status;
+  }
+
+ private:
+  std::unique_ptr<RawConnection> raw_connection_;
+  AuthKeyHandshake *handshake_;
+  std::unique_ptr<AuthKeyHandshakeContext> context_;
+
+  void send_no_crypto(const Storer &storer) override {
+    raw_connection_->send_no_crypto(PacketStorer<NoCryptoImpl>(0, storer));
+  }
+
+  Status on_raw_packet(const PacketInfo &packet_info, BufferSlice packet) override {
+    if (packet_info.no_crypto_flag == false) {
+      return Status::Error("Expected not encrypted packet");
+    }
+
+    // skip header
+    if (packet.size() < 12) {
+      return Status::Error("Result is too small");
+    }
+    packet.confirm_read(12);
+
+    TRY_STATUS(handshake_->on_message(packet.as_slice(), this, context_.get()));
+    return Status::OK();
+  }
+};
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/HttpTransport.cpp b/libs/tdlib/td/td/mtproto/HttpTransport.cpp
new file mode 100644
index 0000000000..2af6624e21
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/HttpTransport.cpp
@@ -0,0 +1,81 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/mtproto/HttpTransport.h"
+
+#include "td/net/HttpHeaderCreator.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+// TODO: do I need \r\n as delimiter?
+
+#include <cstring>
+
+namespace td {
+namespace mtproto {
+namespace http {
+
+Result<size_t> Transport::read_next(BufferSlice *message, uint32 *quick_ack) {
+  CHECK(can_read());
+  auto r_size = reader_.read_next(&http_query_);
+  if (r_size.is_error() || r_size.ok() != 0) {
+    return r_size;
+  }
+  if (http_query_.type_ != HttpQuery::Type::RESPONSE) {
+    return Status::Error("Unexpected http query type");
+  }
+  if (http_query_.container_.size() != 2u) {
+    return Status::Error("Wrong response");
+  }
+  *message = std::move(http_query_.container_[1]);
+  turn_ = Write;
+  return 0;
+}
+
+void Transport::write(BufferWriter &&message, bool quick_ack) {
+  CHECK(can_write());
+  CHECK(!quick_ack);
+  /*
+   * POST /api HTTP/1.1
+   * Content-Length: [message->size()]
+   * Host: url
+   */
+  HttpHeaderCreator hc;
+  hc.init_post("/api");
+  hc.add_header("Host", "");
+  hc.set_keep_alive();
+  hc.set_content_size(message.size());
+  auto r_head = hc.finish();
+  if (r_head.is_error()) {
+    UNREACHABLE();
+  }
+  Slice src = r_head.ok();
+  MutableSlice dst = message.prepare_prepend();
+  CHECK(dst.size() >= src.size()) << dst.size() << " >= " << src.size();
+  std::memcpy(dst.end() - src.size(), src.begin(), src.size());
+  message.confirm_prepend(src.size());
+  output_->append(message.as_buffer_slice());
+  turn_ = Read;
+}
+
+bool Transport::can_read() const {
+  return turn_ == Read;
+}
+
+bool Transport::can_write() const {
+  return turn_ == Write;
+}
+
+size_t Transport::max_prepend_size() const {
+  return MAX_PREPEND_SIZE;
+}
+
+}  // namespace http
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/HttpTransport.h b/libs/tdlib/td/td/mtproto/HttpTransport.h
new file mode 100644
index 0000000000..8e3ed41a7b
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/HttpTransport.h
@@ -0,0 +1,51 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/mtproto/IStreamTransport.h"
+
+#include "td/net/HttpQuery.h"
+#include "td/net/HttpReader.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/Status.h"
+
+namespace td {
+namespace mtproto {
+namespace http {
+class Transport : public IStreamTransport {
+ public:
+  Result<size_t> read_next(BufferSlice *message, uint32 *quick_ack) override TD_WARN_UNUSED_RESULT;
+  bool support_quick_ack() const override {
+    return false;
+  }
+  void write(BufferWriter &&message, bool quick_ack) override;
+  bool can_read() const override;
+  bool can_write() const override;
+  void init(ChainBufferReader *input, ChainBufferWriter *output) override {
+    reader_.init(input);
+    output_ = output;
+  }
+
+  size_t max_prepend_size() const override;
+  TransportType get_type() const override {
+    return TransportType::Http;
+  }
+
+ private:
+  HttpReader reader_;
+  HttpQuery http_query_;
+  ChainBufferWriter *output_;
+  enum { Write, Read } turn_ = Write;
+
+  enum { MAX_PREPEND_SIZE = 96 };
+};
+
+}  // namespace http
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/IStreamTransport.cpp b/libs/tdlib/td/td/mtproto/IStreamTransport.cpp
new file mode 100644
index 0000000000..8440108c71
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/IStreamTransport.cpp
@@ -0,0 +1,28 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/mtproto/IStreamTransport.h"
+
+#include "td/mtproto/HttpTransport.h"
+#include "td/mtproto/TcpTransport.h"
+
+#include "td/utils/logging.h"
+
+namespace td {
+namespace mtproto {
+std::unique_ptr<IStreamTransport> create_transport(TransportType type) {
+  switch (type) {
+    case TransportType::ObfuscatedTcp:
+      return std::make_unique<tcp::ObfuscatedTransport>();
+    case TransportType::Tcp:
+      return std::make_unique<tcp::OldTransport>();
+    case TransportType::Http:
+      return std::make_unique<http::Transport>();
+  }
+  UNREACHABLE();
+}
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/IStreamTransport.h b/libs/tdlib/td/td/mtproto/IStreamTransport.h
new file mode 100644
index 0000000000..6796d457fc
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/IStreamTransport.h
@@ -0,0 +1,34 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/buffer.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/Status.h"
+
+namespace td {
+namespace mtproto {
+enum class TransportType { Tcp, ObfuscatedTcp, Http };
+class IStreamTransport {
+ public:
+  IStreamTransport() = default;
+  IStreamTransport(const IStreamTransport &) = delete;
+  IStreamTransport &operator=(const IStreamTransport &) = delete;
+  virtual ~IStreamTransport() = default;
+  virtual Result<size_t> read_next(BufferSlice *message, uint32 *quick_ack) = 0;
+  virtual bool support_quick_ack() const = 0;
+  virtual void write(BufferWriter &&message, bool quick_ack) = 0;
+  virtual bool can_read() const = 0;
+  virtual bool can_write() const = 0;
+  virtual void init(ChainBufferReader *input, ChainBufferWriter *output) = 0;
+  virtual size_t max_prepend_size() const = 0;
+  virtual TransportType get_type() const = 0;
+};
+
+std::unique_ptr<IStreamTransport> create_transport(TransportType type);
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/NoCryptoStorer.h b/libs/tdlib/td/td/mtproto/NoCryptoStorer.h
new file mode 100644
index 0000000000..2dc92abf24
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/NoCryptoStorer.h
@@ -0,0 +1,28 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/mtproto/PacketStorer.h"
+
+namespace td {
+namespace mtproto {
+class NoCryptoImpl {
+ public:
+  NoCryptoImpl(uint64 message_id, const Storer &data) : message_id(message_id), data(data) {
+  }
+  template <class T>
+  void do_store(T &storer) const {
+    storer.store_binary(message_id);
+    storer.store_binary(static_cast<int32>(data.size()));
+    storer.store_storer(data);
+  }
+
+ private:
+  uint64 message_id;
+  const Storer &data;
+};
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/PacketStorer.h b/libs/tdlib/td/td/mtproto/PacketStorer.h
new file mode 100644
index 0000000000..63c0322ef2
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/PacketStorer.h
@@ -0,0 +1,45 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/Storer.h"
+#include "td/utils/tl_storers.h"
+
+#include <limits>
+
+namespace td {
+namespace mtproto {
+
+template <class Impl>
+class PacketStorer
+    : public Storer
+    , public Impl {
+ public:
+  size_t size() const override {
+    if (size_ != std::numeric_limits<size_t>::max()) {
+      return size_;
+    }
+    TlStorerCalcLength storer;
+    this->do_store(storer);
+    return size_ = storer.get_length();
+  }
+
+  size_t store(uint8 *ptr) const override {
+    char *start = reinterpret_cast<char *>(ptr);
+    TlStorerUnsafe storer(start);
+    this->do_store(storer);
+    return storer.get_buf() - start;
+  }
+
+  using Impl::Impl;
+
+ private:
+  mutable size_t size_ = std::numeric_limits<size_t>::max();
+};
+
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/PingConnection.h b/libs/tdlib/td/td/mtproto/PingConnection.h
new file mode 100644
index 0000000000..b726e48d60
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/PingConnection.h
@@ -0,0 +1,69 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/mtproto/AuthKey.h"
+#include "td/mtproto/NoCryptoStorer.h"
+#include "td/mtproto/RawConnection.h"
+#include "td/mtproto/utils.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/Random.h"
+#include "td/utils/Status.h"
+
+#include "td/mtproto/mtproto_api.h"
+
+namespace td {
+namespace mtproto {
+class PingConnection : private RawConnection::Callback {
+ public:
+  explicit PingConnection(std::unique_ptr<RawConnection> raw_connection) : raw_connection_(std::move(raw_connection)) {
+  }
+
+  Fd &get_pollable() {
+    return raw_connection_->get_pollable();
+  }
+
+  std::unique_ptr<RawConnection> move_as_raw_connection() {
+    return std::move(raw_connection_);
+  }
+
+  void close() {
+    raw_connection_->close();
+  }
+
+  Status flush() {
+    if (!was_ping_) {
+      UInt128 nonce;
+      Random::secure_bytes(nonce.raw, sizeof(nonce));
+      raw_connection_->send_no_crypto(PacketStorer<NoCryptoImpl>(1, create_storer(mtproto_api::req_pq_multi(nonce))));
+      was_ping_ = true;
+    }
+    return raw_connection_->flush(AuthKey(), *this);
+  }
+  bool was_pong() const {
+    return was_pong_;
+  }
+
+  Status on_raw_packet(const PacketInfo &packet_info, BufferSlice packet) override {
+    if (packet.size() < 12) {
+      return Status::Error("Result is too small");
+    }
+    packet.confirm_read(12);
+    // TODO: fetch_result
+    was_pong_ = true;
+    return Status::OK();
+  }
+
+ private:
+  std::unique_ptr<RawConnection> raw_connection_;
+  bool was_ping_ = false;
+  bool was_pong_ = false;
+};
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/RawConnection.cpp b/libs/tdlib/td/td/mtproto/RawConnection.cpp
new file mode 100644
index 0000000000..3595b4bb03
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/RawConnection.cpp
@@ -0,0 +1,126 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/mtproto/RawConnection.h"
+
+#include "td/mtproto/AuthKey.h"
+#include "td/mtproto/Transport.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <utility>
+
+namespace td {
+namespace mtproto {
+
+void RawConnection::send_crypto(const Storer &storer, int64 session_id, int64 salt, const AuthKey &auth_key,
+                                uint64 quick_ack_token) {
+  mtproto::PacketInfo info;
+  info.version = 2;
+  info.no_crypto_flag = false;
+  info.salt = salt;
+  info.session_id = session_id;
+
+  auto packet = BufferWriter{mtproto::Transport::write(storer, auth_key, &info), transport_->max_prepend_size(), 0};
+  mtproto::Transport::write(storer, auth_key, &info, packet.as_slice());
+
+  bool use_quick_ack = false;
+  if (quick_ack_token != 0 && transport_->support_quick_ack()) {
+    auto tmp = quick_ack_to_token_.insert(std::make_pair(info.message_ack, quick_ack_token));
+    if (tmp.second) {
+      use_quick_ack = true;
+    } else {
+      LOG(ERROR) << "quick_ack collision " << tag("quick_ack", info.message_ack);
+    }
+  }
+
+  transport_->write(std::move(packet), use_quick_ack);
+}
+
+uint64 RawConnection::send_no_crypto(const Storer &storer) {
+  mtproto::PacketInfo info;
+
+  info.no_crypto_flag = true;
+  auto packet =
+      BufferWriter{mtproto::Transport::write(storer, mtproto::AuthKey(), &info), transport_->max_prepend_size(), 0};
+  mtproto::Transport::write(storer, mtproto::AuthKey(), &info, packet.as_slice());
+  LOG(INFO) << "Send handshake packet: " << format::as_hex_dump<4>(packet.as_slice());
+  transport_->write(std::move(packet), false);
+  return info.message_id;
+}
+
+Status RawConnection::flush_read(const AuthKey &auth_key, Callback &callback) {
+  auto r = socket_fd_.flush_read();
+  if (r.is_ok() && stats_callback_) {
+    stats_callback_->on_read(r.ok());
+  }
+  while (transport_->can_read()) {
+    BufferSlice packet;
+    uint32 quick_ack = 0;
+    TRY_RESULT(wait_size, transport_->read_next(&packet, &quick_ack));
+    if (wait_size != 0) {
+      break;
+    }
+
+    if (quick_ack != 0) {
+      auto it = quick_ack_to_token_.find(quick_ack);
+      if (it == quick_ack_to_token_.end()) {
+        LOG(WARNING) << Status::Error(PSLICE() << "Unknown " << tag("quick_ack", quick_ack));
+        continue;
+        // TODO: return Status::Error(PSLICE() << "Unknown " << tag("quick_ack", quick_ack));
+      }
+      auto token = it->second;
+      quick_ack_to_token_.erase(it);
+      callback.on_quick_ack(token);
+      continue;
+    }
+
+    MutableSlice data = packet.as_slice();
+    PacketInfo info;
+    info.version = 2;
+
+    int32 error_code = 0;
+    TRY_STATUS(mtproto::Transport::read(data, auth_key, &info, &data, &error_code));
+
+    if (error_code) {
+      if (error_code == -429) {
+        if (stats_callback_) {
+          stats_callback_->on_mtproto_error();
+        }
+        return Status::Error(500, PSLICE() << "Mtproto error: " << error_code);
+      }
+      if (error_code == -404) {
+        return Status::Error(-404, PSLICE() << "Mtproto error: " << error_code);
+      }
+      return Status::Error(PSLICE() << "Mtproto error: " << error_code);
+    }
+
+    // If a packet was successfully decrypted, then it is ok to assume that the connection is alive
+    if (!auth_key.empty()) {
+      if (stats_callback_) {
+        stats_callback_->on_pong();
+      }
+    }
+
+    TRY_STATUS(callback.on_raw_packet(info, packet.from_slice(data)));
+  }
+  TRY_STATUS(std::move(r));
+  return Status::OK();
+}
+
+Status RawConnection::flush_write() {
+  TRY_RESULT(size, socket_fd_.flush_write());
+  if (size > 0 && stats_callback_) {
+    stats_callback_->on_write(size);
+  }
+  return Status::OK();
+}
+
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/RawConnection.h b/libs/tdlib/td/td/mtproto/RawConnection.h
new file mode 100644
index 0000000000..3c989c4122
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/RawConnection.h
@@ -0,0 +1,146 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/mtproto/IStreamTransport.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/BufferedFd.h"
+#include "td/utils/common.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/SocketFd.h"
+#include "td/utils/Status.h"
+
+#include "td/telegram/StateManager.h"
+
+#include <map>
+
+namespace td {
+class Storer;
+namespace mtproto {
+class AuthKey;
+struct PacketInfo;
+}  // namespace mtproto
+}  // namespace td
+
+namespace td {
+namespace mtproto {
+class RawConnection {
+ public:
+  class StatsCallback {
+   public:
+    virtual ~StatsCallback() = default;
+    virtual void on_read(uint64 bytes) = 0;
+    virtual void on_write(uint64 bytes) = 0;
+
+    virtual void on_pong() = 0;   // called when we know that connection is alive
+    virtual void on_error() = 0;  // called on RawConnectin error. Such error should be very rare on good connections.
+    virtual void on_mtproto_error() = 0;
+  };
+  RawConnection() = default;
+  RawConnection(SocketFd socket_fd, TransportType transport_type, std::unique_ptr<StatsCallback> stats_callback)
+      : socket_fd_(std::move(socket_fd))
+      , transport_(create_transport(transport_type))
+      , stats_callback_(std::move(stats_callback)) {
+    transport_->init(&socket_fd_.input_buffer(), &socket_fd_.output_buffer());
+  }
+
+  void set_connection_token(StateManager::ConnectionToken connection_token) {
+    connection_token_ = std::move(connection_token);
+  }
+
+  bool can_send() const {
+    return transport_->can_write();
+  }
+  TransportType get_transport_type() const {
+    return transport_->get_type();
+  }
+  void send_crypto(const Storer &storer, int64 session_id, int64 salt, const AuthKey &auth_key,
+                   uint64 quick_ack_token = 0);
+  uint64 send_no_crypto(const Storer &storer);
+
+  Fd &get_pollable() {
+    return socket_fd_.get_fd();
+  }
+  StatsCallback *stats_callback() {
+    return stats_callback_.get();
+  }
+
+  class Callback {
+   public:
+    Callback() = default;
+    Callback(const Callback &) = delete;
+    Callback &operator=(const Callback &) = delete;
+    virtual ~Callback() = default;
+    virtual Status on_raw_packet(const PacketInfo &info, BufferSlice packet) = 0;
+    virtual Status on_quick_ack(uint64 quick_ack_token) {
+      return Status::Error("quick acks unsupported fully, but still used");
+    }
+    virtual Status before_write() {
+      return Status::OK();
+    }
+  };
+
+  // NB: After first returned error, all subsequent calls will return error too.
+  Status flush(const AuthKey &auth_key, Callback &callback) TD_WARN_UNUSED_RESULT {
+    auto status = do_flush(auth_key, callback);
+    if (status.is_error()) {
+      if (stats_callback_ && status.code() != 2) {
+        stats_callback_->on_error();
+      }
+      has_error_ = true;
+    }
+    return status;
+  }
+
+  bool has_error() const {
+    return has_error_;
+  }
+
+  void close() {
+    transport_.reset();
+    socket_fd_.close();
+  }
+
+  uint32 extra_{0};
+  string debug_str_;
+  double rtt_{0};
+
+ private:
+  BufferedFd<SocketFd> socket_fd_;
+  unique_ptr<IStreamTransport> transport_;
+  std::map<uint32, uint64> quick_ack_to_token_;
+  bool has_error_{false};
+
+  std::unique_ptr<StatsCallback> stats_callback_;
+
+  StateManager::ConnectionToken connection_token_;
+
+  Status flush_read(const AuthKey &auth_key, Callback &callback);
+  Status flush_write();
+
+  Status do_flush(const AuthKey &auth_key, Callback &callback) TD_WARN_UNUSED_RESULT {
+    if (has_error_) {
+      return Status::Error("Connection has already failed");
+    }
+
+    // read/write
+    // EINVAL may be returned in linux kernel < 2.6.28. And on some new kernels too.
+    // just close connection and hope that read or write will not return this error too.
+    TRY_STATUS(socket_fd_.get_pending_error());
+
+    TRY_STATUS(flush_read(auth_key, callback));
+    TRY_STATUS(callback.before_write());
+    TRY_STATUS(flush_write());
+    if (can_close(socket_fd_)) {
+      return Status::Error("Connection closed");
+    }
+    return Status::OK();
+  }
+};
+
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/SessionConnection.cpp b/libs/tdlib/td/td/mtproto/SessionConnection.cpp
new file mode 100644
index 0000000000..4b78d783f5
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/SessionConnection.cpp
@@ -0,0 +1,969 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/mtproto/SessionConnection.h"
+
+#include "td/mtproto/AuthData.h"
+#include "td/mtproto/AuthKey.h"
+#include "td/mtproto/CryptoStorer.h"
+#include "td/mtproto/Handshake.h"
+#include "td/mtproto/NoCryptoStorer.h"
+
+#include "td/mtproto/HttpTransport.h"
+#include "td/mtproto/TcpTransport.h"
+#include "td/mtproto/Transport.h"
+
+#include "td/utils/format.h"
+#include "td/utils/Gzip.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Random.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Time.h"
+#include "td/utils/tl_parsers.h"
+
+#include "td/mtproto/mtproto_api.h"
+#include "td/mtproto/mtproto_api.hpp"
+
+#include <algorithm>
+#include <iterator>
+#include <type_traits>
+
+namespace td {
+namespace mtproto_api {
+
+const int32 msg_container::ID;
+
+class rpc_result {
+ public:
+  static const int32 ID = -212046591;
+};
+
+}  // namespace mtproto_api
+
+namespace mtproto {
+/**
+ * TODO-list.
+ *
+ * 1. Should I check input salt?
+ *
+ * 1. Cancellation of rpc request
+ *  input:
+ *   - rpc_drop_answer#58e4a740 req_msg_id:long = RpcDropAnswer;
+ *  output:
+ *   - rpc_answer_unknown#5e2ad36e = RpcDropAnswer;
+ *    no ack
+ *   - rpc_answer_dropped_running#cd78e586 = RpcDropAnswer;
+ *    same answer will be returned to original query
+ *    ack
+ *   - rpc_answer_dropped#a43ad8b7 msg_id:long seq_no:int bytes:int = RpcDropAnswer;
+ *    ack
+ *  Alternative is destroy session
+ *
+ * 5. Destroy session
+ * (?) when session will be destroyed otherwise
+ *  Must be call in different session
+ *  input:
+ *   - destroy_session#e7512126 session_id:long = DestroySessionRes;
+ *  output:
+ *   - destroy_session_ok#e22045fc session_id:long = DestroySessionRes;
+ *   - destroy_session_none#62d350c9 session_id:long = DestroySessionRes;
+ *
+
+ * DONE:
+ * 3. Ping pong
+ *  input:
+ *   - ping#7abe77ec ping_id:long = Pong;
+ *   - pong#347773c5 msg_id:long ping_id:long = Pong;
+ *
+ * 4. Ping + deferred connection closure
+ *  input:
+ *   - ping_delay_disconnect#f3427b8c ping_id:long disconnect_delay:int = Pong;
+ *
+ * 6. New session creation
+ *  Notification about new session.
+ *  It is reasonable to store unique_id with current session, in order to process duplicated notifications once.
+ *
+ *  Causes all older than first_msg_id to be re-sent.
+ *  Also there is a gap in updates, so getDifference MUST be sent
+ *  output:
+ *   - new_session_created#9ec20908 first_msg_id:long unique_id:long server_salt:long = NewSession
+ *
+ *
+ * 7. Containers
+ *   I should pack output messages as containers
+ *   - msg_container#73f1f8dc messages:vector message = MessageContainer;
+ *     message msg_id:long seqno:int bytes:int body:Object = Message;
+ *
+ * 8. Packed Object
+ *  I should pack big output messages with gzip
+ *   - gzip_packed#3072cfa1 packed_data:string = Object;
+ *
+ * 9. Ack
+ *  I should actually send acks
+ *  (?) Does updates need ack
+ *  - msgs_ack#62d6b459 msg_ids:Vector long = MsgsAck;
+ *
+ * 10. Errors
+ *  output:
+ *   - bad_msg_notification#a7eff811 bad_msg_id:long bad_msg_seqno:int error_code:int = BadMsgNotification;
+ *   - bad_server_salt#edab447b bad_msg_id:long bad_msg_seqno:int error_code:int new_server_salt:long =
+ *         BadMsgNotification;
+ *
+ *  error codes:
+ *   16: msg_id is too low. -- lite resend. It will be automatially packed in a container. I hope.
+ *   17: msg_id is too high. -- fail connection.
+ *   18: msg_id % 4 != 0. -- Error and fail connection.
+ *   19: container msg_id is the same as msg_id of a previously received message. MUST NEVER HAPPENS. Error and fail
+ *   connection.
+ *
+ *   20: message is to old -- full resend. (or fail query, if we are afraid of double send)
+ *
+ *   32: seq_no is too low. (msg_id1 < msg_id2 <==> seq_no1 < seq_no2). Error and fail connection
+ *   33: seq_no is too high. Error and fail connection.
+ *   34: (?) an even msg_seqno expected (irrelevant message), but odd received. (Fail and call a developer...)
+ *   35: (?) odd msg_seqno expected (relevant message), but even received (Fail and call a developer)
+ *
+ *   48: incorrect server salt (in bad_server_salt message)
+ *
+ *   64: (?) invalid container
+ *
+ * 2. Get future salts
+ *  input:
+ *   - get_future_salts#b921bd04 num:int = FutureSalts;
+ *  output:
+ *   - future_salts#ae500895 req_msg_id:long now:int salts:vector future_salt = FutureSalts;
+ *     future_salt#0949d9dc valid_since:int valid_until:int salt:long = FutureSalt;
+ *
+ * 1. ping-pong
+ * 3. Delayed ack.
+ * 4. Delayed packet.
+ * HTTP transport (support of several connections)
+ * get future salts
+ *
+ * 11. Explicit request of messages states
+ *  input:
+ *   - msgs_state_req#da69fb52 msg_ids:Vector long = MsgsStateReq;
+ * 12. States of messages in answer
+ *  output:
+ *   - msgs_state_info#04deb57d req_msg_id:long info:string = MsgsStateInfo;
+ *  info contain one byte for each queired msg_id
+ *  bytes:
+ *    1: unknown message_id
+ *    2: message not received (msg_id in stored range)
+ *    3: message not receiver (msg_id is too high)
+ *    4: message received. No extra ack will be sent
+ *    +8: message is already acknowledged
+ *    +16: message don't requires acknowledgement
+ *    +32: RPC query contained in message being processed or the processing has already been completed
+ *    +64: content-related response to message has already been generated
+ *    +128: other party knows for a fact that message is already received
+ *
+ * 13. Voluntary Communication of Status of Messages
+ *  output:
+ *   - msgs_all_info#8cc0d131 msg_ids:Vector long info:string = MsgsAllInfo
+ *
+ */
+
+class OnPacket {
+  const MsgInfo &info_;
+  SessionConnection *connection_;
+  Status *status_;
+
+ public:
+  OnPacket(const MsgInfo &info, SessionConnection *connection, Status *status)
+      : info_(info), connection_(connection), status_(status) {
+  }
+
+  template <class T>
+  void operator()(const T &func) const {
+    *status_ = connection_->on_packet(info_, func);
+  }
+};
+
+/*** SessionConnection ***/
+BufferSlice SessionConnection::as_buffer_slice(Slice packet) {
+  return current_buffer_slice->from_slice(packet);
+}
+
+Status SessionConnection::parse_message(TlParser &parser, MsgInfo *info, Slice *packet, bool crypto_flag) {
+  // msg_id:long seqno:int bytes:int
+  parser.check_len(sizeof(int64) + (crypto_flag ? sizeof(int32) : 0) + sizeof(int32));
+  if (parser.get_error() != nullptr) {
+    return Status::Error(PSLICE() << "Failed to parse mtproto_api::message: " << parser.get_error());
+  }
+  info->message_id = parser.fetch_long_unsafe();
+  if (crypto_flag) {
+    info->seq_no = parser.fetch_int_unsafe();
+  }
+  uint32 bytes = parser.fetch_int_unsafe();
+
+  if (bytes % sizeof(int32) != 0) {
+    return Status::Error(PSLICE() << "Failed to parse mtproto_api::message: size of message [" << bytes
+                                  << "] is not divisible by 4");
+  }
+
+  *packet = parser.fetch_string_raw<Slice>(bytes);
+  if (parser.get_error() != nullptr) {
+    return Status::Error(PSLICE() << "Failed to parse mtproto_api::message: " << parser.get_error());
+  }
+
+  info->size = bytes;
+
+  return Status::OK();
+}
+
+Status SessionConnection::on_packet_container(const MsgInfo &info, Slice packet) {
+  auto old_container_id = container_id_;
+  container_id_ = info.message_id;
+  SCOPE_EXIT {
+    container_id_ = old_container_id;
+  };
+
+  TlParser parser(packet);
+  parser.fetch_int();
+  int32 size = parser.fetch_int();
+  if (parser.get_error()) {
+    return Status::Error(PSLICE() << "Failed to parse mtproto_api::rpc_container: " << parser.get_error());
+  }
+  for (int i = 0; i < size; i++) {
+    TRY_STATUS(parse_packet(parser));
+  }
+  return Status::OK();
+}
+
+Status SessionConnection::on_packet_rpc_result(const MsgInfo &info, Slice packet) {
+  TlParser parser(packet);
+  parser.fetch_int();
+  uint64 req_msg_id = parser.fetch_long();
+  if (parser.get_error()) {
+    return Status::Error(PSLICE() << "Failed to parse mtproto_api::rpc_result: " << parser.get_error());
+  }
+
+  auto object_begin_pos = packet.size() - parser.get_left_len();
+  int32 id = parser.fetch_int();
+  if (id == mtproto_api::rpc_error::ID) {
+    mtproto_api::rpc_error rpc_error(parser);
+    if (parser.get_error()) {
+      return Status::Error(PSLICE() << "Failed to parse mtproto_api::rpc_error: " << parser.get_error());
+    }
+    return on_packet(info, req_msg_id, rpc_error);
+  } else if (id == mtproto_api::gzip_packed::ID) {
+    mtproto_api::gzip_packed gzip(parser);
+    if (parser.get_error()) {
+      return Status::Error(PSLICE() << "Failed to parse mtproto_api::gzip_packed: " << parser.get_error());
+    }
+    // yep, gzip in rpc_result
+    BufferSlice object = gzdecode(gzip.packed_data_);
+    // send header no more optimization
+    return callback_->on_message_result_ok(req_msg_id, std::move(object), info.size);
+  }
+
+  return callback_->on_message_result_ok(req_msg_id, as_buffer_slice(packet.substr(object_begin_pos)), info.size);
+}
+
+template <class T>
+Status SessionConnection::on_packet(const MsgInfo &info, const T &packet) {
+  LOG(ERROR) << "Unsupported: " << to_string(packet);
+  return Status::OK();
+}
+
+Status SessionConnection::on_packet(const MsgInfo &info, const mtproto_api::rpc_error &rpc_error) {
+  return on_packet(info, 0, rpc_error);
+}
+
+Status SessionConnection::on_packet(const MsgInfo &info, uint64 req_msg_id, const mtproto_api::rpc_error &rpc_error) {
+  VLOG(mtproto) << "ERROR [code:" << rpc_error.error_code_ << "] [msg:" << rpc_error.error_message_.str().c_str()
+                << "]";
+  if (req_msg_id != 0) {
+    callback_->on_message_result_error(req_msg_id, rpc_error.error_code_, as_buffer_slice(rpc_error.error_message_));
+  } else {
+    LOG(WARNING) << "rpc_error as update: [" << rpc_error.error_code_ << "][" << rpc_error.error_message_ << "]";
+  }
+  return Status::OK();
+}
+
+Status SessionConnection::on_packet(const MsgInfo &info, const mtproto_api::new_session_created &new_session_created) {
+  VLOG(mtproto) << "NEW_SESSION_CREATED: [first_msg_id:" << format::as_hex(new_session_created.first_msg_id_)
+                << "] [unique_id:" << format::as_hex(new_session_created.unique_id_)
+                << "] [server_salt:" << format::as_hex(new_session_created.server_salt_) << "]";
+  callback_->on_session_created(new_session_created.unique_id_, new_session_created.first_msg_id_);
+  return Status::OK();
+}
+
+Status SessionConnection::on_packet(const MsgInfo &info,
+                                    const mtproto_api::bad_msg_notification &bad_msg_notification) {
+  MsgInfo bad_info{info.session_id, bad_msg_notification.bad_msg_id_, bad_msg_notification.bad_msg_seqno_, 0};
+  enum Code {
+    MsgIdTooLow = 16,
+    MsgIdTooHigh = 17,
+    MsgIdMod4 = 18,
+    MsgIdCollision = 19,
+
+    MsgIdTooOld = 20,
+
+    SeqNoTooLow = 32,
+    SeqNoTooHigh = 33,
+    SeqNoNotEven = 34,
+    SeqNoNotOdd = 35,
+
+    InvalidContainer = 64
+  };
+  Slice common = " BUG! CALL FOR A DEVELOPER! Session will be closed";
+  switch (bad_msg_notification.error_code_) {
+    case MsgIdTooLow: {
+      LOG(WARNING) << bad_info << ": MessageId is too low. Message will be re-sent";
+      // time will be updated automagically
+      on_message_failed(bad_info.message_id, Status::Error("MessageId is too low"));
+      break;
+    }
+    case MsgIdTooHigh: {
+      LOG(ERROR) << bad_info << ": MessageId is too high. Session will be closed";
+      // All this queries will be re-sent by parent
+      to_send_.clear();
+      callback_->on_session_failed(Status::Error("MessageId is too high"));
+      return Status::Error("MessageId is too high");
+    }
+    case MsgIdMod4: {
+      LOG(ERROR) << bad_info << ": MessageId is not divisible by 4." << common;
+      return Status::Error("MessageId is not divisible by 4");
+    }
+    case MsgIdCollision: {
+      LOG(ERROR) << bad_info << ": Container and older message MessageId collision." << common;
+      return Status::Error("Container and older message MessageId collision");
+    }
+
+    case MsgIdTooOld: {
+      LOG(WARNING) << bad_info << ": MessageId is too old. Message will be re-sent";
+      on_message_failed(bad_info.message_id, Status::Error("MessageId is too old"));
+      break;
+    }
+
+    case SeqNoTooLow: {
+      LOG(ERROR) << bad_info << ": SeqNo is too low." << common;
+      return Status::Error("SeqNo is too low");
+    }
+    case SeqNoTooHigh: {
+      LOG(ERROR) << bad_info << ": SeqNo is too high." << common;
+      return Status::Error("SeqNo is too high");
+    }
+    case SeqNoNotEven: {
+      LOG(ERROR) << bad_info << ": SeqNo is not even for an irrelevant message." << common;
+      return Status::Error("SeqNo is not even for an irrelevant message");
+    }
+    case SeqNoNotOdd: {
+      LOG(ERROR) << bad_info << ": SeqNo is not odd for an irrelevant message." << common;
+      return Status::Error("SeqNo is not odd for an irrelevant message");
+    }
+
+    case InvalidContainer: {
+      LOG(ERROR) << bad_info << ": Invalid Contailer." << common;
+      return Status::Error("Invalid Contailer");
+    }
+
+    default: {
+      LOG(ERROR) << bad_info << ": Unknown error [code:" << bad_msg_notification.error_code_ << "]." << common;
+      return Status::Error("Unknown error code");
+    }
+  }
+  return Status::OK();
+}
+
+Status SessionConnection::on_packet(const MsgInfo &info, const mtproto_api::bad_server_salt &bad_server_salt) {
+  MsgInfo bad_info{info.session_id, bad_server_salt.bad_msg_id_, bad_server_salt.bad_msg_seqno_, 0};
+  VLOG(mtproto) << "BAD_SERVER_SALT: " << bad_info;
+  auth_data_->set_server_salt(bad_server_salt.new_server_salt_, Time::now_cached());
+  callback_->on_server_salt_updated();
+
+  on_message_failed(bad_info.message_id, Status::Error("Bad server salt"));
+  return Status::OK();
+}
+
+Status SessionConnection::on_packet(const MsgInfo &info, const mtproto_api::msgs_ack &msgs_ack) {
+  for (auto id : msgs_ack.msg_ids_) {
+    callback_->on_message_ack(id);
+  }
+  return Status::OK();
+}
+
+Status SessionConnection::on_packet(const MsgInfo &info, const mtproto_api::gzip_packed &gzip_packed) {
+  BufferSlice res = gzdecode(gzip_packed.packed_data_);
+  auto guard = set_buffer_slice(&res);
+  return on_slice_packet(info, res.as_slice());
+}
+
+Status SessionConnection::on_packet(const MsgInfo &info, const mtproto_api::pong &pong) {
+  VLOG(mtproto) << "PONG";
+  last_pong_at_ = Time::now_cached();
+  return callback_->on_pong();
+}
+Status SessionConnection::on_packet(const MsgInfo &info, const mtproto_api::future_salts &salts) {
+  VLOG(mtproto) << "FUTURE_SALTS";
+  std::vector<ServerSalt> new_salts;
+  for (auto &it : salts.salts_) {
+    new_salts.push_back(
+        ServerSalt{it->salt_, static_cast<double>(it->valid_since_), static_cast<double>(it->valid_until_)});
+  }
+  auth_data_->set_future_salts(new_salts, Time::now_cached());
+  callback_->on_server_salt_updated();
+
+  return Status::OK();
+}
+
+Status SessionConnection::on_msgs_state_info(const std::vector<int64> &ids, Slice info) {
+  if (ids.size() != info.size()) {
+    return Status::Error(PSLICE() << tag("ids.size()", ids.size()) << "!=" << tag("info.size()", info.size()));
+  }
+  size_t i = 0;
+  for (auto id : ids) {
+    callback_->on_message_info(id, info[i], 0, 0);
+    i++;
+  }
+  return Status::OK();
+}
+
+Status SessionConnection::on_packet(const MsgInfo &info, const mtproto_api::msgs_state_info &msgs_state_info) {
+  auto it = service_queries_.find(msgs_state_info.req_msg_id_);
+  if (it == service_queries_.end()) {
+    return Status::Error("Unknown msgs_state_info");
+  }
+  SCOPE_EXIT {
+    service_queries_.erase(it);
+  };
+  if (it->second.type != ServiceQuery::GetStateInfo) {
+    return Status::Error("Got msg_state_info in response not to GetStateInfo");
+  }
+  return on_msgs_state_info(it->second.message_ids, msgs_state_info.info_);
+}
+
+Status SessionConnection::on_packet(const MsgInfo &info, const mtproto_api::msgs_all_info &msgs_all_info) {
+  return on_msgs_state_info(msgs_all_info.msg_ids_, msgs_all_info.info_);
+}
+
+Status SessionConnection::on_packet(const MsgInfo &info, const mtproto_api::msg_detailed_info &msg_detailed_info) {
+  callback_->on_message_info(msg_detailed_info.msg_id_, msg_detailed_info.status_, msg_detailed_info.answer_msg_id_,
+                             msg_detailed_info.bytes_);
+  return Status::OK();
+}
+
+Status SessionConnection::on_packet(const MsgInfo &info,
+                                    const mtproto_api::msg_new_detailed_info &msg_new_detailed_info) {
+  callback_->on_message_info(0, 0, msg_new_detailed_info.answer_msg_id_, msg_new_detailed_info.bytes_);
+  return Status::OK();
+}
+
+Status SessionConnection::on_slice_packet(const MsgInfo &info, Slice packet) {
+  if (info.seq_no & 1) {
+    send_ack(info.message_id);
+  }
+  TlParser parser(packet);
+  tl_object_ptr<mtproto_api::Object> object = mtproto_api::Object::fetch(parser);
+  if (parser.get_error()) {
+    // msg_container is not real tl object
+    if (packet.size() >= 4 && as<int32>(packet.begin()) == mtproto_api::msg_container::ID) {
+      return on_packet_container(info, packet);
+    }
+    if (packet.size() >= 4 && as<int32>(packet.begin()) == mtproto_api::rpc_result::ID) {
+      return on_packet_rpc_result(info, packet);
+    }
+
+    // It is an update... I hope.
+    auto status = auth_data_->check_update(info.message_id);
+    if (status.is_error()) {
+      VLOG(mtproto) << "Skip update " << info.message_id << " from " << get_name() << " created in "
+                    << (Time::now() - created_at_) << ": " << status;
+      return Status::OK();
+    } else {
+      VLOG(mtproto) << "Got update from " << get_name() << " created in " << (Time::now() - created_at_)
+                    << " in container " << container_id_ << " from session " << auth_data_->session_id_
+                    << " with message_id " << info.message_id << ", main_message_id = " << main_message_id_
+                    << ", seq_no = " << info.seq_no << " and original size " << info.size;
+      return callback_->on_message_result_ok(0, as_buffer_slice(packet), info.size);
+    }
+  }
+
+  Status status;
+  downcast_call(*object, OnPacket(info, this, &status));
+  return status;
+}
+
+Status SessionConnection::parse_packet(TlParser &parser) {
+  MsgInfo info;
+  Slice packet;
+  TRY_STATUS(parse_message(parser, &info, &packet, true));
+  return on_slice_packet(info, packet);
+}
+
+Status SessionConnection::on_main_packet(const PacketInfo &info, Slice packet) {
+  // Update pong here too. Real pong can be delayed by lots of big packets
+  last_pong_at_ = Time::now_cached();
+
+  if (!connected_flag_) {
+    connected_flag_ = true;
+    callback_->on_connected();
+  }
+
+  VLOG(raw_mtproto) << "Got packet: [session_id:" << format::as_hex(info.session_id) << "] "
+                    << format::as_hex_dump<4>(packet);
+  if (info.no_crypto_flag) {
+    return Status::Error("Unencrypted packet");
+  }
+
+  TlParser parser(packet);
+  TRY_STATUS(parse_packet(parser));
+  parser.fetch_end();
+  if (parser.get_error()) {
+    return Status::Error(PSLICE() << "Failed to parse packet: " << parser.get_error());
+  }
+  return Status::OK();
+}
+
+void SessionConnection::on_message_failed(uint64 id, Status status) {
+  callback_->on_message_failed(id, std::move(status));
+
+  if (id == last_ping_message_id_ || id == last_ping_container_id_) {
+    // restart ping immediately
+    last_ping_at_ = 0;
+    last_ping_message_id_ = 0;
+    last_ping_container_id_ = 0;
+  }
+
+  auto cit = container_to_service_msg_.find(id);
+  if (cit != container_to_service_msg_.end()) {
+    for (auto nid : cit->second) {
+      on_message_failed_inner(nid);
+    }
+  } else {
+    on_message_failed_inner(id);
+  }
+}
+void SessionConnection::on_message_failed_inner(uint64 id) {
+  auto it = service_queries_.find(id);
+  if (it == service_queries_.end()) {
+    return;
+  }
+  switch (it->second.type) {
+    case ServiceQuery::ResendAnswer: {
+      for (auto message_id : it->second.message_ids) {
+        resend_answer(message_id);
+      }
+      break;
+    }
+    case ServiceQuery::GetStateInfo: {
+      for (auto message_id : it->second.message_ids) {
+        get_state_info(message_id);
+      }
+      break;
+    }
+  }
+  service_queries_.erase(id);
+}
+
+bool SessionConnection::must_flush_packet() {
+  flush_packet_at_ = 0;
+
+  // we need key to send just something
+  if (!auth_data_->has_auth_key(Time::now_cached())) {
+    return false;
+  }
+
+  // transport is ready
+  if (!raw_connection_->can_send()) {
+    return false;
+  }
+
+  bool has_salt = auth_data_->has_salt(Time::now_cached());
+  // do not send anything in long poll connection before we have salt
+  if (mode_ == Mode::HttpLongPoll && !has_salt) {
+    return false;
+  }
+
+  // http_wait
+  if (mode_ == Mode::HttpLongPoll) {
+    return true;
+  }
+  // queries and acks (+ resend & get_info)
+  if (has_salt && force_send_at_ != 0) {
+    if (Time::now_cached() > force_send_at_) {
+      return true;
+    } else {
+      relax_timeout_at(&flush_packet_at_, force_send_at_);
+    }
+  }
+
+  // ping
+  if (has_salt) {
+    if (must_ping()) {
+      return true;
+    }
+    relax_timeout_at(&flush_packet_at_, last_ping_at_ + ping_must_delay());
+  }
+  // get_future_salt
+  if (!has_salt) {
+    auto get_future_salts_at = last_get_future_salt_at_ + 60;
+    if (get_future_salts_at < Time::now_cached()) {
+      return true;
+    }
+    relax_timeout_at(&flush_packet_at_, get_future_salts_at);
+  }
+
+  return false;
+}
+
+Status SessionConnection::before_write() {
+  while (must_flush_packet()) {
+    flush_packet();
+  }
+  return Status::OK();
+}
+
+Status SessionConnection::on_raw_packet(const td::mtproto::PacketInfo &info, BufferSlice packet) {
+  auto old_main_message_id = main_message_id_;
+  main_message_id_ = info.message_id;
+  SCOPE_EXIT {
+    main_message_id_ = old_main_message_id;
+  };
+
+  if (info.no_crypto_flag) {
+    return Status::Error("Unexpected unencrypted packet");
+  }
+
+  bool time_difference_was_updated = false;
+  auto status =
+      auth_data_->check_packet(info.session_id, info.message_id, Time::now_cached(), time_difference_was_updated);
+  if (time_difference_was_updated) {
+    callback_->on_server_time_difference_updated();
+  }
+  if (status.is_error()) {
+    if (status.code() == 1) {
+      LOG(WARNING) << "Packet ignored " << status;
+      send_ack(info.message_id);
+      return Status::OK();
+    } else {
+      return status;
+    }
+  }
+
+  auto guard = set_buffer_slice(&packet);
+  TRY_STATUS(on_main_packet(info, packet.as_slice()));
+  return Status::OK();
+}
+
+Status SessionConnection::on_quick_ack(uint64 quick_ack_token) {
+  callback_->on_message_ack(quick_ack_token);
+  return Status::OK();
+}
+SessionConnection::SessionConnection(Mode mode, std::unique_ptr<RawConnection> raw_connection, AuthData *auth_data,
+                                     DhCallback *dh_callback)
+    : raw_connection_(std::move(raw_connection)), auth_data_(auth_data), dh_callback_(dh_callback) {
+  state_ = Init;
+  mode_ = mode;
+  created_at_ = Time::now();
+}
+
+Fd &SessionConnection::get_pollable() {
+  return raw_connection_->get_pollable();
+}
+
+Status SessionConnection::init() {
+  CHECK(state_ == Init);
+  last_pong_at_ = Time::now_cached();
+  state_ = Run;
+  return Status::OK();
+}
+
+void SessionConnection::set_online(bool online_flag) {
+  online_flag_ = online_flag;
+  if (online_flag_) {
+    last_pong_at_ = Time::now_cached() - ping_disconnect_delay() + rtt();  // disconnect if no ping in 1 second
+  } else {
+    last_pong_at_ = Time::now_cached();
+  }
+  last_ping_at_ = 0;
+  last_ping_message_id_ = 0;
+  last_ping_container_id_ = 0;
+}
+
+void SessionConnection::do_close(Status status) {
+  state_ = Closed;
+  callback_->on_before_close();
+  raw_connection_->close();
+  // NB: this could be destroyed after on_closed
+  callback_->on_closed(std::move(status));
+}
+
+void SessionConnection::send_crypto(const Storer &storer, uint64 quick_ack_token) {
+  CHECK(state_ != Closed);
+  raw_connection_->send_crypto(storer, auth_data_->get_session_id(), auth_data_->get_server_salt(Time::now_cached()),
+                               auth_data_->get_auth_key(), quick_ack_token);
+}
+
+Result<uint64> SessionConnection::send_query(BufferSlice buffer, bool gzip_flag, int64 message_id,
+                                             uint64 invoke_after_id, bool use_quick_ack) {
+  CHECK(mode_ != Mode::HttpLongPoll) << "LongPoll connection is only for http_wait";
+  if (message_id == 0) {
+    message_id = auth_data_->next_message_id(Time::now_cached());
+  }
+  auto seq_no = auth_data_->next_seq_no(true);
+  if (to_send_.empty()) {
+    send_before(Time::now_cached() + QUERY_DELAY);
+  }
+  to_send_.push_back(Query{message_id, seq_no, std::move(buffer), gzip_flag, invoke_after_id, use_quick_ack});
+
+  return message_id;
+}
+
+void SessionConnection::get_state_info(int64 message_id) {
+  if (to_get_state_info_.empty()) {
+    send_before(Time::now_cached());
+  }
+  to_get_state_info_.push_back(message_id);
+}
+
+void SessionConnection::resend_answer(int64 message_id) {
+  if (to_resend_answer_.empty()) {
+    send_before(Time::now_cached() + RESEND_ANSWER_DELAY);
+  }
+  to_resend_answer_.push_back(message_id);
+}
+void SessionConnection::cancel_answer(int64 message_id) {
+  if (to_cancel_answer_.empty()) {
+    send_before(Time::now_cached() + RESEND_ANSWER_DELAY);
+  }
+  to_cancel_answer_.push_back(message_id);
+}
+
+std::pair<uint64, BufferSlice> SessionConnection::encrypted_bind(int64 perm_key, int64 nonce, int32 expire_at) {
+  int64 temp_key = auth_data_->get_tmp_auth_key().id();
+
+  mtproto_api::bind_auth_key_inner object(nonce, temp_key, perm_key, auth_data_->session_id_, expire_at);
+  auto object_storer = create_storer(object);
+  auto object_packet = BufferWriter{object_storer.size(), 0, 0};
+  object_storer.store(object_packet.as_slice().ubegin());
+
+  Query query{auth_data_->next_message_id(Time::now_cached()), 0, object_packet.as_buffer_slice(), false, 0, false};
+  PacketStorer<QueryImpl> query_storer(query, Slice());
+
+  mtproto::PacketInfo info;
+  info.version = 1;
+  info.no_crypto_flag = false;
+  info.salt = Random::secure_int64();
+  info.session_id = Random::secure_int64();
+
+  auto packet = BufferWriter{mtproto::Transport::write(query_storer, auth_data_->get_main_auth_key(), &info), 0, 0};
+  mtproto::Transport::write(query_storer, auth_data_->get_main_auth_key(), &info, packet.as_slice());
+  return std::make_pair(query.message_id, packet.as_buffer_slice());
+}
+
+void SessionConnection::send_ack(uint64 message_id) {
+  VLOG(mtproto) << "Send ack: [msg_id:" << format::as_hex(message_id) << "]";
+  if (to_ack_.empty()) {
+    send_before(Time::now_cached() + ACK_DELAY);
+  }
+  auto ack = static_cast<int64>(message_id);
+  // an easiest way to eliminate duplicated acks for gzipped packets
+  if (to_ack_.empty() || to_ack_.back() != ack) {
+    to_ack_.push_back(ack);
+  }
+}
+
+// don't send ping in poll mode.
+bool SessionConnection::may_ping() const {
+  return last_ping_at_ == 0 || (mode_ != Mode::HttpLongPoll && last_ping_at_ + ping_may_delay() < Time::now_cached());
+}
+
+bool SessionConnection::must_ping() const {
+  return last_ping_at_ == 0 || (mode_ != Mode::HttpLongPoll && last_ping_at_ + ping_must_delay() < Time::now_cached());
+}
+
+void SessionConnection::flush_packet() {
+  bool has_salt = auth_data_->has_salt(Time::now_cached());
+  // ping
+  uint64 container_id = 0;
+  int64 ping_id = 0;
+  if (has_salt && may_ping()) {
+    ping_id = ++cur_ping_id_;
+    last_ping_at_ = Time::now_cached();
+  }
+
+  // http_wait
+  int max_delay = -1;
+  int max_after = -1;
+  int max_wait = -1;
+  if (mode_ == Mode::HttpLongPoll) {
+    max_delay = HTTP_MAX_DELAY;
+    max_after = HTTP_MAX_AFTER;
+    max_wait = min(http_max_wait(),
+                   static_cast<int>(1000 * max(0.1, ping_disconnect_delay() + last_pong_at_ - Time::now_cached() - 1)));
+  } else if (mode_ == Mode::Http) {
+    max_delay = HTTP_MAX_DELAY;
+    max_after = HTTP_MAX_AFTER;
+    max_wait = 0;
+  }
+
+  // future salts
+  int future_salt_n = 0;
+  if (mode_ != Mode::HttpLongPoll) {
+    if (auth_data_->need_future_salts(Time::now_cached()) && last_get_future_salt_at_ + 60 < Time::now_cached()) {
+      last_get_future_salt_at_ = Time::now_cached();
+      future_salt_n = 64;
+    }
+  }
+
+  size_t send_till = 0, send_size = 0;
+  // send at most 1020 queries, of total size 2^15
+  // don't send anything if have no salt
+  if (has_salt) {
+    while (send_till < to_send_.size() && send_till < 1020 && send_size < (1 << 15)) {
+      send_size += to_send_[send_till].packet.size();
+      send_till++;
+    }
+  }
+  std::vector<Query> queries;
+  if (send_till == to_send_.size()) {
+    queries = std::move(to_send_);
+  } else if (send_till != 0) {
+    queries.reserve(send_till);
+    std::move(to_send_.begin(), to_send_.begin() + send_till, std::back_inserter(queries));
+    to_send_.erase(to_send_.begin(), to_send_.begin() + send_till);
+  }
+
+  if (queries.empty() && to_ack_.empty() && ping_id == 0 && max_delay < 0 && future_salt_n == 0 &&
+      to_resend_answer_.empty() && to_cancel_answer_.empty() && to_get_state_info_.empty()) {
+    force_send_at_ = 0;
+    return;
+  }
+
+  VLOG(mtproto) << "Sent packet: " << tag("query_count", queries.size()) << tag("ack_cnt", to_ack_.size())
+                << tag("ping", ping_id != 0) << tag("http_wait", max_delay >= 0)
+                << tag("future_salt", future_salt_n > 0) << tag("get_info", to_get_state_info_.size())
+                << tag("resend", to_resend_answer_.size()) << tag("cancel", to_cancel_answer_.size())
+                << tag("auth_id", auth_data_->get_auth_key().id());
+
+  auto cut_tail = [](auto &v, size_t size, Slice name) {
+    if (size >= v.size()) {
+      return std::move(v);
+    }
+    LOG(WARNING) << "Too much ids in container: " << v.size() << " " << name;
+    std::decay_t<decltype(v)> res(std::make_move_iterator(v.end() - size), std::make_move_iterator(v.end()));
+    v.resize(v.size() - size);
+    return res;
+  };
+
+  // no more than 8192 ids per container..
+  auto to_resend_answer = cut_tail(to_resend_answer_, 8192, "resend_answer");
+  uint64 resend_answer_id = 0;
+  CHECK(queries.size() <= 1020);
+  auto to_cancel_answer = cut_tail(to_cancel_answer_, 1020 - queries.size(), "cancel_answer");
+  auto to_get_state_info = cut_tail(to_get_state_info_, 8192, "get_state_info");
+  uint64 get_state_info_id = 0;
+  auto to_ack = cut_tail(to_ack_, 8192, "ack");
+  uint64 ping_message_id = 0;
+
+  bool use_quick_ack =
+      std::any_of(queries.begin(), queries.end(), [](const auto &query) { return query.use_quick_ack; });
+
+  {
+    uint64 parent_message_id = 0;
+    auto storer = PacketStorer<CryptoImpl>(
+        queries, auth_data_->header(), std::move(to_ack), ping_id, ping_disconnect_delay() + 2, max_delay, max_after,
+        max_wait, future_salt_n, to_get_state_info, to_resend_answer, to_cancel_answer, auth_data_, &container_id,
+        &get_state_info_id, &resend_answer_id, &ping_message_id, &parent_message_id);
+
+    auto quick_ack_token = use_quick_ack ? parent_message_id : 0;
+    send_crypto(storer, quick_ack_token);
+  }
+
+  if (resend_answer_id) {
+    service_queries_.insert({resend_answer_id, ServiceQuery{ServiceQuery::ResendAnswer, std::move(to_resend_answer)}});
+  }
+  if (get_state_info_id) {
+    service_queries_.insert(
+        {get_state_info_id, ServiceQuery{ServiceQuery::GetStateInfo, std::move(to_get_state_info)}});
+  }
+  if (ping_id != 0) {
+    last_ping_container_id_ = container_id;
+    last_ping_message_id_ = ping_message_id;
+  }
+
+  if (container_id != 0) {
+    vector<uint64> ids = transform(queries, [](const Query &x) { return static_cast<uint64>(x.message_id); });
+
+    // some acks may be lost here. Nobody will resend them if something goes wrong with query.
+    // It is mostly problem for server. We will just drop this answers in next connection
+    //
+    // get future salt too.
+    // So I will re-ask salt if have no answer in 60 second.
+    callback_->on_container_sent(container_id, std::move(ids));
+
+    if (resend_answer_id) {
+      container_to_service_msg_[container_id].push_back(resend_answer_id);
+    }
+    if (get_state_info_id) {
+      container_to_service_msg_[container_id].push_back(get_state_info_id);
+    }
+  }
+
+  to_ack_.clear();
+  if (to_send_.empty()) {
+    force_send_at_ = 0;
+  }
+}
+
+void SessionConnection::send_before(double tm) {
+  if (force_send_at_ == 0 || force_send_at_ > tm) {
+    force_send_at_ = tm;
+  }
+}
+
+Status SessionConnection::do_flush() {
+  CHECK(state_ != Closed);
+  if (state_ == Init) {
+    TRY_STATUS(init());
+  }
+  if (!auth_data_->has_auth_key(Time::now_cached())) {
+    return Status::Error("No auth key");
+  }
+
+  TRY_STATUS(raw_connection_->flush(auth_data_->get_auth_key(), *this));
+
+  // check last pong
+  if (last_pong_at_ != 0 && last_pong_at_ + ping_disconnect_delay() < Time::now_cached()) {
+    raw_connection_->stats_callback()->on_error();
+    return Status::Error("No pong :(");
+  }
+
+  return Status::OK();
+}
+
+double SessionConnection::flush(SessionConnection::Callback *callback) {
+  callback_ = callback;
+  wakeup_at_ = 0;
+  auto status = do_flush();
+  // check error
+  if (status.is_error()) {
+    do_close(std::move(status));
+    return 0;
+  }
+
+  // wakeup_at
+  // two independent timeouts
+  // 1. close connection after PING_DISCONNECT_DELAY after last_pong.
+  // 2. the one returned by must_flush_packet
+  relax_timeout_at(&wakeup_at_, last_pong_at_ + ping_disconnect_delay() + 0.002);
+  // CHECK(wakeup_at > Time::now_cached());
+
+  relax_timeout_at(&wakeup_at_, flush_packet_at_);
+  return wakeup_at_;
+}
+
+void SessionConnection::force_close(SessionConnection::Callback *callback) {
+  CHECK(state_ != Closed);
+  callback_ = callback;
+  do_close(Status::OK());
+}
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/SessionConnection.h b/libs/tdlib/td/td/mtproto/SessionConnection.h
new file mode 100644
index 0000000000..be3c1de895
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/SessionConnection.h
@@ -0,0 +1,253 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/mtproto/crypto.h"
+#include "td/mtproto/RawConnection.h"
+#include "td/mtproto/utils.h"
+
+#include "td/actor/actor.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/format.h"
+#include "td/utils/Named.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tl_parsers.h"
+
+#include <unordered_map>
+#include <utility>
+
+namespace td {
+namespace mtproto_api {
+
+class msg_container {
+ public:
+  static const int32 ID = 0x73f1f8dc;
+};
+
+class rpc_error;
+class new_session_created;
+class bad_msg_notification;
+class bad_server_salt;
+class msgs_ack;
+class gzip_packed;
+class pong;
+class future_salts;
+class msgs_state_info;
+class msgs_all_info;
+class msg_detailed_info;
+class msg_new_detailed_info;
+}  // namespace mtproto_api
+
+namespace mtproto {
+class AuthData;
+struct PacketInfo;
+
+struct MsgInfo {
+  uint64 session_id;
+  int64 message_id;
+  int32 seq_no;
+  size_t size;
+};
+
+inline StringBuilder &operator<<(StringBuilder &stream, const MsgInfo &id) {
+  return stream << "[session_id:" << format::as_hex(id.session_id) << "] [msg_id:" << format::as_hex(id.message_id)
+                << "] [seq_no:" << format::as_hex(id.seq_no) << "]";
+}
+
+class SessionConnection
+    : public Named
+    , private RawConnection::Callback {
+ public:
+  enum class Mode { Tcp, Http, HttpLongPoll };
+  SessionConnection(Mode mode, std::unique_ptr<RawConnection> raw_connection, AuthData *auth_data,
+                    DhCallback *dh_callback);
+
+  Fd &get_pollable();
+
+  // Interface
+  Result<uint64> TD_WARN_UNUSED_RESULT send_query(BufferSlice buffer, bool gzip_flag, int64 message_id = 0,
+                                                  uint64 invoke_after_id = 0, bool use_quick_ack = false);
+  std::pair<uint64, BufferSlice> encrypted_bind(int64 perm_key, int64 nonce, int32 expire_at);
+
+  void get_state_info(int64 message_id);
+  void resend_answer(int64 message_id);
+  void cancel_answer(int64 message_id);
+
+  void set_online(bool online_flag);
+
+  // Callback
+  class Callback {
+   public:
+    Callback() = default;
+    Callback(const Callback &) = delete;
+    Callback &operator=(const Callback &) = delete;
+    virtual ~Callback() = default;
+
+    virtual void on_connected() = 0;
+    virtual void on_before_close() = 0;
+    virtual void on_closed(Status status) = 0;
+
+    virtual void on_auth_key_updated() = 0;
+    virtual void on_tmp_auth_key_updated() = 0;
+    virtual void on_server_salt_updated() = 0;
+    virtual void on_server_time_difference_updated() = 0;
+
+    virtual void on_session_created(uint64 unique_id, uint64 first_id) = 0;
+    virtual void on_session_failed(Status status) = 0;
+
+    virtual void on_container_sent(uint64 container_id, vector<uint64> msgs_id) = 0;
+    virtual Status on_pong() = 0;
+
+    virtual void on_message_ack(uint64 id) = 0;
+    virtual Status on_message_result_ok(uint64 id, BufferSlice packet, size_t original_size) = 0;
+    virtual void on_message_result_error(uint64 id, int code, BufferSlice descr) = 0;
+    virtual void on_message_failed(uint64 id, Status status) = 0;
+    virtual void on_message_info(uint64 id, int32 state, uint64 answer_id, int32 answer_size) = 0;
+  };
+
+  double flush(SessionConnection::Callback *callback);
+
+  // NB: Do not call force_close after on_closed callback
+  void force_close(SessionConnection::Callback *callback);
+
+ private:
+  static constexpr int ACK_DELAY = 30;                  // 30s
+  static constexpr double QUERY_DELAY = 0.001;          // 0.001s
+  static constexpr double RESEND_ANSWER_DELAY = 0.001;  // 0.001s
+
+  bool online_flag_ = false;
+
+  int rtt() const {
+    return max(2, static_cast<int>(raw_connection_->rtt_ * 1.5));
+  }
+
+  int32 ping_disconnect_delay() const {
+    return online_flag_ ? rtt() * 5 / 2 : 135;
+  }
+
+  int32 ping_may_delay() const {
+    return online_flag_ ? rtt() / 2 : 30;
+  }
+
+  int32 ping_must_delay() const {
+    return online_flag_ ? rtt() : 60;
+  }
+
+  int http_max_wait() const {
+    return 25 * 1000;  // 25s. Longer could be closed by proxy
+  }
+  static constexpr int HTTP_MAX_AFTER = 10;              // 0.001s
+  static constexpr int HTTP_MAX_DELAY = 30;              // 0.003s
+  static constexpr int TEMP_KEY_TIMEOUT = 60 * 60 * 24;  // one day
+
+  vector<Query> to_send_;
+  vector<int64> to_ack_;
+  double force_send_at_ = 0;
+
+  struct ServiceQuery {
+    enum Type { GetStateInfo, ResendAnswer } type;
+    std::vector<int64> message_ids;
+  };
+  std::vector<int64> to_resend_answer_;
+  std::vector<int64> to_cancel_answer_;
+  std::vector<int64> to_get_state_info_;
+  std::unordered_map<uint64, ServiceQuery> service_queries_;
+
+  // nobody cleans up this map. But it should be really small.
+  std::unordered_map<uint64, std::vector<uint64>> container_to_service_msg_;
+
+  double last_ping_at_ = 0;
+  double last_pong_at_ = 0;
+  int64 cur_ping_id_ = 0;
+  uint64 last_ping_message_id_ = 0;
+  uint64 last_ping_container_id_ = 0;
+
+  double wakeup_at_ = 0;
+  double flush_packet_at_ = 0;
+
+  double last_get_future_salt_at_ = 0;
+  enum { Init, Run, Fail, Closed } state_;
+  Mode mode_;
+  bool connected_flag_ = false;
+
+  uint64 container_id_ = 0;
+  int64 main_message_id_ = 0;
+  double created_at_ = 0;
+
+  std::unique_ptr<RawConnection> raw_connection_;
+  AuthData *auth_data_;
+  SessionConnection::Callback *callback_ = nullptr;
+  DhCallback *dh_callback_;
+  BufferSlice *current_buffer_slice;
+
+  friend class OnPacket;
+
+  BufferSlice as_buffer_slice(Slice packet);
+  auto set_buffer_slice(BufferSlice *buffer_slice) TD_WARN_UNUSED_RESULT {
+    auto old_buffer_slice = current_buffer_slice;
+    current_buffer_slice = buffer_slice;
+    return ScopeExit() + [&to = current_buffer_slice, from = old_buffer_slice] { to = from; };
+  }
+
+  Status parse_message(TlParser &parser, MsgInfo *info, Slice *packet, bool crypto_flag = true) TD_WARN_UNUSED_RESULT;
+  Status parse_packet(TlParser &parser) TD_WARN_UNUSED_RESULT;
+  Status on_packet_container(const MsgInfo &info, Slice packet) TD_WARN_UNUSED_RESULT;
+  Status on_packet_rpc_result(const MsgInfo &info, Slice packet) TD_WARN_UNUSED_RESULT;
+  Status on_packet(const MsgInfo &info, uint64 req_msg_id,
+                   const mtproto_api::rpc_error &rpc_error) TD_WARN_UNUSED_RESULT;
+
+  template <class T>
+  Status on_packet(const MsgInfo &info, const T &packet) TD_WARN_UNUSED_RESULT;
+
+  Status on_packet(const MsgInfo &info, const mtproto_api::rpc_error &rpc_error) TD_WARN_UNUSED_RESULT;
+  Status on_packet(const MsgInfo &info,
+                   const mtproto_api::new_session_created &new_session_created) TD_WARN_UNUSED_RESULT;
+  Status on_packet(const MsgInfo &info,
+                   const mtproto_api::bad_msg_notification &bad_msg_notification) TD_WARN_UNUSED_RESULT;
+  Status on_packet(const MsgInfo &info, const mtproto_api::bad_server_salt &bad_server_salt) TD_WARN_UNUSED_RESULT;
+  Status on_packet(const MsgInfo &info, const mtproto_api::msgs_ack &msgs_ack) TD_WARN_UNUSED_RESULT;
+  Status on_packet(const MsgInfo &info, const mtproto_api::gzip_packed &gzip_packed) TD_WARN_UNUSED_RESULT;
+  Status on_packet(const MsgInfo &info, const mtproto_api::pong &pong) TD_WARN_UNUSED_RESULT;
+  Status on_packet(const MsgInfo &info, const mtproto_api::future_salts &salts) TD_WARN_UNUSED_RESULT;
+
+  Status on_msgs_state_info(const std::vector<int64> &ids, Slice info) TD_WARN_UNUSED_RESULT;
+  Status on_packet(const MsgInfo &info, const mtproto_api::msgs_state_info &msgs_state_info) TD_WARN_UNUSED_RESULT;
+  Status on_packet(const MsgInfo &info, const mtproto_api::msgs_all_info &msgs_all_info) TD_WARN_UNUSED_RESULT;
+  Status on_packet(const MsgInfo &info, const mtproto_api::msg_detailed_info &msg_detailed_info) TD_WARN_UNUSED_RESULT;
+  Status on_packet(const MsgInfo &info,
+                   const mtproto_api::msg_new_detailed_info &msg_new_detailed_info) TD_WARN_UNUSED_RESULT;
+
+  Status on_slice_packet(const MsgInfo &info, Slice packet) TD_WARN_UNUSED_RESULT;
+  Status on_main_packet(const PacketInfo &info, Slice packet) TD_WARN_UNUSED_RESULT;
+  void on_message_failed(uint64 id, Status status);
+  void on_message_failed_inner(uint64 id);
+
+  void do_close(Status status);
+
+  void send_ack(uint64 message_id);
+  void send_crypto(const Storer &storer, uint64 quick_ack_token);
+  void send_before(double tm);
+  bool may_ping() const;
+  bool must_ping() const;
+  bool must_flush_packet();
+  void flush_packet();
+
+  Status init() TD_WARN_UNUSED_RESULT;
+  Status process_packet(const PacketInfo &info, Slice packet) TD_WARN_UNUSED_RESULT;
+  Status flush_read() TD_WARN_UNUSED_RESULT;
+  Status do_flush() TD_WARN_UNUSED_RESULT;
+
+  Status before_write() override TD_WARN_UNUSED_RESULT;
+  Status on_raw_packet(const td::mtproto::PacketInfo &info, BufferSlice packet) override;
+  Status on_quick_ack(uint64 quick_ack_token) override;
+};
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/TcpTransport.cpp b/libs/tdlib/td/td/mtproto/TcpTransport.cpp
new file mode 100644
index 0000000000..e7613acab0
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/TcpTransport.cpp
@@ -0,0 +1,173 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/mtproto/TcpTransport.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/Random.h"
+#include "td/utils/Slice.h"
+
+#include <algorithm>
+
+namespace td {
+namespace mtproto {
+namespace tcp {
+size_t IntermediateTransport::read_from_stream(ChainBufferReader *stream, BufferSlice *message, uint32 *quick_ack) {
+  CHECK(message);
+  size_t stream_size = stream->size();
+  size_t header_size = 4;
+  if (stream->size() < header_size) {
+    return header_size;
+  }
+  uint32 data_size;
+  auto it = stream->clone();
+  it.advance(header_size, MutableSlice(reinterpret_cast<uint8 *>(&data_size), sizeof(data_size)));
+  if (data_size & (1u << 31)) {
+    if (quick_ack) {
+      *quick_ack = data_size;
+    }
+    stream->advance(header_size);
+    return 0;
+  }
+
+  size_t total_size = data_size + header_size;
+  if (stream_size < total_size) {
+    // optimization
+    // stream->make_solid(total_size);
+    return total_size;
+  }
+
+  stream->advance(header_size);
+  *message = stream->cut_head(data_size).move_as_buffer_slice();
+  return 0;
+}
+
+void IntermediateTransport::write_prepare_inplace(BufferWriter *message, bool quick_ack) {
+  size_t size = message->size();
+  CHECK(size % 4 == 0);
+  CHECK(size < (1 << 24));
+  if (quick_ack) {
+    size |= static_cast<size_t>(1) << 31;
+  }
+
+  size_t prepend_size = 4;
+  MutableSlice prepend = message->prepare_prepend();
+  CHECK(prepend.size() >= prepend_size);
+  message->confirm_prepend(prepend_size);
+
+  as<uint32>(message->as_slice().begin()) = static_cast<uint32>(size);
+}
+
+void IntermediateTransport::init_output_stream(ChainBufferWriter *stream) {
+  const uint32 magic = 0xeeeeeeee;
+  stream->append(Slice(reinterpret_cast<const char *>(&magic), 4));
+}
+
+size_t AbridgedTransport::read_from_stream(ChainBufferReader *stream, BufferSlice *message, uint32 *quick_ack) {
+  if (stream->empty()) {
+    return 1;
+  }
+  uint8 byte = 0;
+  stream->clone().advance(1, MutableSlice(&byte, 1));
+  size_t header_size;
+  uint32 data_size;
+  if (byte < 0x7f) {
+    header_size = 1;
+    data_size = byte * 4u;
+  } else {
+    if (stream->size() < 4) {
+      return 4;
+    }
+    header_size = 4;
+    stream->clone().advance(4, MutableSlice(reinterpret_cast<char *>(&data_size), sizeof(data_size)));
+    data_size >>= 8;
+    data_size = data_size * 4;
+  }
+
+  size_t total_size = header_size + data_size;
+  if (stream->size() < total_size) {
+    // optimization
+    // stream->make_solid(total_size);
+    return total_size;
+  }
+
+  stream->advance(header_size);
+  *message = stream->cut_head(data_size).move_as_buffer_slice();
+  return 0;
+}
+
+void AbridgedTransport::write_prepare_inplace(BufferWriter *message, bool quick_ack) {
+  CHECK(!quick_ack);
+  size_t size = message->size() / 4;
+  CHECK(size % 4 == 0);
+  CHECK(size < 1 << 24);
+
+  size_t prepend_size = size >= 0x7f ? 4 : 1;
+
+  MutableSlice prepend = message->prepare_prepend();
+  CHECK(prepend.size() >= prepend_size);
+  message->confirm_prepend(prepend_size);
+
+  MutableSlice data = message->as_slice();
+  if (size >= 0x7f) {
+    uint32 size_encoded = 0x7f + (static_cast<uint32>(size) << 8);
+    as<uint32>(data.begin()) = size_encoded;
+  } else {
+    as<uint8>(data.begin()) = static_cast<uint8>(size);
+  }
+}
+
+void AbridgedTransport::init_output_stream(ChainBufferWriter *stream) {
+  const uint8 magic = 0xef;
+  stream->append(Slice(&magic, 1));
+}
+
+void ObfuscatedTransport::init(ChainBufferReader *input, ChainBufferWriter *output) {
+  input_ = input;
+  output_ = output;
+
+  const size_t header_size = 64;
+  string header(header_size, '\0');
+  MutableSlice header_slice = header;
+  int32 try_cnt = 0;
+  while (true) {
+    try_cnt++;
+    CHECK(try_cnt < 10);
+    Random::secure_bytes(header_slice.ubegin(), header.size());
+    if (as<uint8>(header.data()) == 0xef) {
+      continue;
+    }
+    auto first_int = as<uint32>(header.data());
+    if (first_int == 0x44414548 || first_int == 0x54534f50 || first_int == 0x20544547 || first_int == 0x4954504f ||
+        first_int == 0xeeeeeeee) {
+      continue;
+    }
+    auto second_int = as<uint32>(header.data() + sizeof(uint32));
+    if (second_int == 0) {
+      continue;
+    }
+    break;
+  }
+  // TODO: It is actually IntermediateTransport::init_output_stream, so it will work only with
+  // TransportImpl==IntermediateTransport
+  as<uint32>(header_slice.begin() + 56) = 0xeeeeeeee;
+
+  string rheader = header;
+  std::reverse(rheader.begin(), rheader.end());
+  aes_ctr_byte_flow_.init(as<UInt256>(rheader.data() + 8), as<UInt128>(rheader.data() + 8 + 32));
+  aes_ctr_byte_flow_.set_input(input_);
+  aes_ctr_byte_flow_ >> byte_flow_sink_;
+
+  output_key_ = as<UInt256>(header.data() + 8);
+  output_state_.init(output_key_, as<UInt128>(header.data() + 8 + 32));
+  output_->append(header_slice.substr(0, 56));
+  output_state_.encrypt(header_slice, header_slice);
+  output_->append(header_slice.substr(56, 8));
+}
+
+}  // namespace tcp
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/TcpTransport.h b/libs/tdlib/td/td/mtproto/TcpTransport.h
new file mode 100644
index 0000000000..d53048478e
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/TcpTransport.h
@@ -0,0 +1,162 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/mtproto/IStreamTransport.h"
+
+#include "td/utils/AesCtrByteFlow.h"
+#include "td/utils/buffer.h"
+#include "td/utils/ByteFlow.h"
+#include "td/utils/common.h"
+#include "td/utils/crypto.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/Status.h"
+
+namespace td {
+namespace mtproto {
+namespace tcp {
+class ITransport {
+  // Writes packet into message.
+  // Returns 0 if everything is ok, and [expected_size] otherwise.
+  // There is no sense to call this function when [stream->size > expected_size]
+  //
+  // (tpc is stream-base protocol. So the input message is a stream, not a slice)
+  virtual size_t read_from_stream(ChainBufferReader *stream, BufferSlice *message, uint32 *quick_ack) = 0;
+
+  // Writes header inplace.
+  virtual void write_prepare_inplace(BufferWriter *message, bool quick_ack) = 0;
+
+  // Writes first several bytes into output stream.
+  virtual void init_output_stream(ChainBufferWriter *stream) = 0;
+
+  virtual bool support_quick_ack() const = 0;
+
+ public:
+  ITransport() = default;
+  ITransport(const ITransport &) = delete;
+  ITransport &operator=(const ITransport &) = delete;
+  ITransport(ITransport &&) = delete;
+  ITransport &operator=(ITransport &&) = delete;
+  virtual ~ITransport() = default;
+};
+
+class AbridgedTransport : public ITransport {
+ public:
+  size_t read_from_stream(ChainBufferReader *stream, BufferSlice *message, uint32 *quick_ack) override;
+  void write_prepare_inplace(BufferWriter *message, bool quick_ack) override;
+  void init_output_stream(ChainBufferWriter *stream) override;
+  bool support_quick_ack() const override {
+    return false;
+  }
+};
+
+class IntermediateTransport : ITransport {
+ public:
+  size_t read_from_stream(ChainBufferReader *stream, BufferSlice *message, uint32 *quick_ack) override;
+  void write_prepare_inplace(BufferWriter *message, bool quick_ack) override;
+  void init_output_stream(ChainBufferWriter *stream) override;
+  bool support_quick_ack() const override {
+    return true;
+  }
+};
+
+using TransportImpl = IntermediateTransport;
+
+class OldTransport : public IStreamTransport {
+ public:
+  OldTransport() = default;
+  Result<size_t> read_next(BufferSlice *message, uint32 *quick_ack) override TD_WARN_UNUSED_RESULT {
+    return impl_.read_from_stream(input_, message, quick_ack);
+  }
+  bool support_quick_ack() const override {
+    return impl_.support_quick_ack();
+  }
+  void write(BufferWriter &&message, bool quick_ack) override {
+    impl_.write_prepare_inplace(&message, quick_ack);
+    output_->append(message.as_buffer_slice());
+  }
+  void init(ChainBufferReader *input, ChainBufferWriter *output) override {
+    input_ = input;
+    output_ = output;
+    impl_.init_output_stream(output_);
+  }
+  bool can_read() const override {
+    return true;
+  }
+  bool can_write() const override {
+    return true;
+  }
+
+  size_t max_prepend_size() const override {
+    return 4;
+  }
+  TransportType get_type() const override {
+    return TransportType::Tcp;
+  }
+
+ private:
+  TransportImpl impl_;
+  ChainBufferReader *input_;
+  ChainBufferWriter *output_;
+};
+
+class ObfuscatedTransport : public IStreamTransport {
+ public:
+  ObfuscatedTransport() = default;
+  Result<size_t> read_next(BufferSlice *message, uint32 *quick_ack) override TD_WARN_UNUSED_RESULT {
+    aes_ctr_byte_flow_.wakeup();
+    return impl_.read_from_stream(byte_flow_sink_.get_output(), message, quick_ack);
+  }
+
+  bool support_quick_ack() const override {
+    return impl_.support_quick_ack();
+  }
+
+  void write(BufferWriter &&message, bool quick_ack) override {
+    impl_.write_prepare_inplace(&message, quick_ack);
+    auto slice = message.as_buffer_slice();
+    output_state_.encrypt(slice.as_slice(), slice.as_slice());
+    output_->append(std::move(slice));
+  }
+
+  void init(ChainBufferReader *input, ChainBufferWriter *output) override;
+
+  bool can_read() const override {
+    return true;
+  }
+
+  bool can_write() const override {
+    return true;
+  }
+
+  size_t max_prepend_size() const override {
+    return 4;
+  }
+
+  TransportType get_type() const override {
+    return TransportType::ObfuscatedTcp;
+  }
+
+ private:
+  TransportImpl impl_;
+  AesCtrByteFlow aes_ctr_byte_flow_;
+  ByteFlowSink byte_flow_sink_;
+  ChainBufferReader *input_;
+
+  // TODO: use ByteFlow?
+  // One problem is that BufferedFd owns output_buffer_
+  // The other problem is that first 56 bytes must be sent unencrypted.
+  UInt256 output_key_;
+  AesCtrState output_state_;
+  ChainBufferWriter *output_;
+};
+
+using Transport = ObfuscatedTransport;
+
+}  // namespace tcp
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/Transport.cpp b/libs/tdlib/td/td/mtproto/Transport.cpp
new file mode 100644
index 0000000000..0e65c82ee7
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/Transport.cpp
@@ -0,0 +1,323 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/mtproto/Transport.h"
+
+#include "td/mtproto/AuthKey.h"
+#include "td/mtproto/crypto.h"
+
+#include "td/utils/crypto.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/Random.h"
+#include "td/utils/Status.h"
+
+#include <array>
+
+namespace td {
+namespace mtproto {
+
+// mtproto v1.0
+template <class HeaderT>
+std::tuple<uint32, UInt128> Transport::calc_message_ack_and_key(const HeaderT &head, size_t data_size) {
+  Slice part(head.encrypt_begin(), head.data + data_size);
+  UInt<160> message_sha1;
+  sha1(part, message_sha1.raw);
+  return std::make_tuple(as<uint32>(message_sha1.raw) | (1u << 31), as<UInt128>(message_sha1.raw + 4));
+}
+
+template <class HeaderT>
+size_t Transport::calc_crypto_size(size_t data_size) {
+  size_t enc_size = HeaderT::encrypted_header_size();
+  size_t raw_size = sizeof(HeaderT) - enc_size;
+  return raw_size + ((enc_size + data_size + 15) & ~15);
+}
+
+// mtproto v2.0
+std::tuple<uint32, UInt128> Transport::calc_message_key2(const AuthKey &auth_key, int X, Slice to_encrypt) {
+  // msg_key_large = SHA256 (substr (auth_key, 88+x, 32) + plaintext + random_padding);
+  Sha256State state;
+  sha256_init(&state);
+  sha256_update(Slice(auth_key.key()).substr(88 + X, 32), &state);
+  sha256_update(to_encrypt, &state);
+
+  uint8 msg_key_large_raw[32];
+  MutableSlice msg_key_large(msg_key_large_raw, sizeof(msg_key_large_raw));
+  sha256_final(&state, msg_key_large);
+
+  // msg_key = substr (msg_key_large, 8, 16);
+  UInt128 res_raw;
+  MutableSlice res(res_raw.raw, sizeof(res_raw.raw));
+  res.copy_from(msg_key_large.substr(8, 16));
+
+  return std::make_tuple(as<uint32>(msg_key_large_raw) | (1u << 31), res_raw);
+}
+
+template <class HeaderT>
+size_t Transport::calc_crypto_size2(size_t data_size) {
+  size_t enc_size = HeaderT::encrypted_header_size();
+  size_t raw_size = sizeof(HeaderT) - enc_size;
+  size_t encrypted_size = (enc_size + data_size + 12 + 15) & ~15;
+  std::array<size_t, 10> sizes{{64, 128, 192, 256, 384, 512, 768, 1024, 1280}};
+  for (auto size : sizes) {
+    if (encrypted_size <= size) {
+      return raw_size + size;
+    }
+  }
+  encrypted_size = (encrypted_size - 1280 + 447) / 448 * 448 + 1280;
+
+  return raw_size + encrypted_size;
+}
+
+size_t Transport::calc_no_crypto_size(size_t data_size) {
+  return sizeof(NoCryptoHeader) + data_size;
+}
+
+Status Transport::read_no_crypto(MutableSlice message, PacketInfo *info, MutableSlice *data) {
+  if (message.size() < sizeof(NoCryptoHeader)) {
+    return Status::Error(PSLICE() << "Invalid mtproto message: too small [message.size()=" << message.size()
+                                  << "] < [sizeof(NoCryptoHeader) = " << sizeof(NoCryptoHeader) << "]");
+  }
+  auto &header = as<NoCryptoHeader>(message.begin());
+  size_t data_size = message.size() - sizeof(NoCryptoHeader);
+  CHECK(message.size() == calc_no_crypto_size(data_size));
+  *data = MutableSlice(header.data, data_size);
+  return Status::OK();
+}
+
+template <class HeaderT, class PrefixT>
+Status Transport::read_crypto_impl(int X, MutableSlice message, const AuthKey &auth_key, HeaderT **header_ptr,
+                                   PrefixT **prefix_ptr, MutableSlice *data, PacketInfo *info) {
+  if (message.size() < sizeof(HeaderT)) {
+    return Status::Error(PSLICE() << "Invalid mtproto message: too small [message.size()=" << message.size()
+                                  << "] < [sizeof(HeaderT) = " << sizeof(HeaderT) << "]");
+  }
+  auto *header = &as<HeaderT>(message.begin());
+  *header_ptr = header;
+  auto to_decrypt = MutableSlice(header->encrypt_begin(), message.uend());
+  if (to_decrypt.size() % 16 != 0) {
+    return Status::Error(PSLICE() << "Invalid mtproto message: size of encrypted part is not multiple of 16 [size="
+                                  << to_decrypt.size() << "]");
+  }
+
+  if (header->auth_key_id != auth_key.id()) {
+    return Status::Error(PSLICE() << "Invalid mtproto message: auth_key_id mismatch [found="
+                                  << format::as_hex(header->auth_key_id)
+                                  << "] [expected=" << format::as_hex(auth_key.id()) << "]");
+  }
+
+  UInt256 aes_key;
+  UInt256 aes_iv;
+  if (info->version == 1) {
+    KDF(auth_key.key(), header->message_key, X, &aes_key, &aes_iv);
+  } else {
+    KDF2(auth_key.key(), header->message_key, X, &aes_key, &aes_iv);
+  }
+
+  aes_ige_decrypt(aes_key, &aes_iv, to_decrypt, to_decrypt);
+
+  size_t tail_size = message.end() - reinterpret_cast<char *>(header->data);
+  if (tail_size < sizeof(PrefixT)) {
+    return Status::Error("Too small encrypted part");
+  }
+  auto *prefix = &as<PrefixT>(header->data);
+  *prefix_ptr = prefix;
+  size_t data_size = prefix->message_data_length + sizeof(PrefixT);
+  bool is_length_ok = prefix->message_data_length % 4 == 0;
+  UInt128 real_message_key;
+
+  if (info->version == 1) {
+    auto expected_size = calc_crypto_size<HeaderT>(data_size);
+    is_length_ok = (is_length_ok & (expected_size == message.size())) != 0;
+    auto check_size = data_size * is_length_ok + tail_size * (1 - is_length_ok);
+    std::tie(info->message_ack, real_message_key) = calc_message_ack_and_key(*header, check_size);
+  } else {
+    size_t pad_size = tail_size - data_size;
+    is_length_ok = (is_length_ok & (tail_size - sizeof(PrefixT) >= prefix->message_data_length) & (12 <= pad_size) &
+                    (pad_size <= 1024)) != 0;
+    std::tie(info->message_ack, real_message_key) = calc_message_key2(auth_key, X, to_decrypt);
+  }
+
+  bool is_key_ok = true;
+  for (size_t i = 0; i < sizeof(real_message_key.raw); i++) {
+    is_key_ok &= real_message_key.raw[i] == header->message_key.raw[i];
+  }
+
+  if (!is_key_ok) {
+    return Status::Error(PSLICE() << "Invalid mtproto message: message_key mismatch [found="
+                                  << format::as_hex_dump(header->message_key)
+                                  << "] [expected=" << format::as_hex_dump(real_message_key) << "]");
+  }
+  if (!is_length_ok) {
+    return Status::Error(PSLICE() << "Invalid mtproto message: invalid length " << tag("total_size", message.size())
+                                  << tag("message_data_length", prefix->message_data_length));
+  }
+
+  *data = MutableSlice(header->data, data_size);
+  return Status::OK();
+}
+
+Status Transport::read_crypto(MutableSlice message, const AuthKey &auth_key, PacketInfo *info, MutableSlice *data) {
+  CryptoHeader *header = nullptr;
+  CryptoPrefix *prefix = nullptr;
+  TRY_STATUS(read_crypto_impl(8, message, auth_key, &header, &prefix, data, info));
+  CHECK(header != nullptr);
+  CHECK(prefix != nullptr);
+  CHECK(info != nullptr);
+  info->type = PacketInfo::Common;
+  info->salt = header->salt;
+  info->session_id = header->session_id;
+  info->message_id = prefix->message_id;
+  info->seq_no = prefix->seq_no;
+  return Status::OK();
+}
+Status Transport::read_e2e_crypto(MutableSlice message, const AuthKey &auth_key, PacketInfo *info, MutableSlice *data) {
+  EndToEndHeader *header = nullptr;
+  EndToEndPrefix *prefix = nullptr;
+  TRY_STATUS(read_crypto_impl(info->is_creator && info->version != 1 ? 8 : 0, message, auth_key, &header, &prefix, data,
+                              info));
+  CHECK(header != nullptr);
+  CHECK(prefix != nullptr);
+  CHECK(info != nullptr);
+  info->type = PacketInfo::EndToEnd;
+  return Status::OK();
+}
+
+size_t Transport::write_no_crypto(const Storer &storer, PacketInfo *info, MutableSlice dest) {
+  size_t size = calc_no_crypto_size(storer.size());
+  if (size > dest.size()) {
+    return size;
+  }
+  auto &header = as<NoCryptoHeader>(dest.begin());
+  header.auth_key_id = 0;
+  storer.store(header.data);
+  return size;
+}
+
+template <class HeaderT>
+void Transport::write_crypto_impl(int X, const Storer &storer, const AuthKey &auth_key, PacketInfo *info,
+                                  HeaderT *header, size_t data_size) {
+  storer.store(header->data);
+  VLOG(raw_mtproto) << "SEND" << format::as_hex_dump<4>(Slice(header->data, data_size));
+  // LOG(ERROR) << "SEND" << format::as_hex_dump<4>(Slice(header->data, data_size)) << info->version;
+
+  size_t size = 0;
+  if (info->version == 1) {
+    size = calc_crypto_size<HeaderT>(data_size);
+  } else {
+    size = calc_crypto_size2<HeaderT>(data_size);
+  }
+
+  size_t pad_size = size - (sizeof(HeaderT) + data_size);
+  MutableSlice pad(header->data + data_size, pad_size);
+  Random::secure_bytes(pad.ubegin(), pad.size());
+  MutableSlice to_encrypt = MutableSlice(header->encrypt_begin(), pad.uend());
+
+  if (info->version == 1) {
+    std::tie(info->message_ack, info->message_key) = calc_message_ack_and_key(*header, data_size);
+  } else {
+    std::tie(info->message_ack, info->message_key) = calc_message_key2(auth_key, X, to_encrypt);
+  }
+
+  header->message_key = info->message_key;
+
+  UInt256 aes_key;
+  UInt256 aes_iv;
+  if (info->version == 1) {
+    KDF(auth_key.key(), header->message_key, X, &aes_key, &aes_iv);
+  } else {
+    KDF2(auth_key.key(), header->message_key, X, &aes_key, &aes_iv);
+  }
+
+  aes_ige_encrypt(aes_key, &aes_iv, to_encrypt, to_encrypt);
+}
+
+size_t Transport::write_crypto(const Storer &storer, const AuthKey &auth_key, PacketInfo *info, MutableSlice dest) {
+  size_t data_size = storer.size();
+  size_t size;
+  if (info->version == 1) {
+    size = calc_crypto_size<CryptoHeader>(data_size);
+  } else {
+    size = calc_crypto_size2<CryptoHeader>(data_size);
+  }
+  if (size > dest.size()) {
+    return size;
+  }
+
+  auto &header = as<CryptoHeader>(dest.begin());
+  header.auth_key_id = auth_key.id();
+  header.salt = info->salt;
+  header.session_id = info->session_id;
+
+  write_crypto_impl(0, storer, auth_key, info, &header, data_size);
+
+  return size;
+}
+
+size_t Transport::write_e2e_crypto(const Storer &storer, const AuthKey &auth_key, PacketInfo *info, MutableSlice dest) {
+  size_t data_size = storer.size();
+  size_t size;
+  if (info->version == 1) {
+    size = calc_crypto_size<EndToEndHeader>(data_size);
+  } else {
+    size = calc_crypto_size2<EndToEndHeader>(data_size);
+  }
+  if (size > dest.size()) {
+    return size;
+  }
+
+  auto &header = as<EndToEndHeader>(dest.begin());
+  header.auth_key_id = auth_key.id();
+
+  write_crypto_impl(info->is_creator || info->version == 1 ? 0 : 8, storer, auth_key, info, &header, data_size);
+
+  return size;
+}
+
+Result<uint64> Transport::read_auth_key_id(Slice message) {
+  if (message.size() < 8) {
+    return Status::Error(PSLICE() << "Invalid mtproto message: smaller than 8 bytes [size=" << message.size() << "]");
+  }
+  return as<uint64>(message.begin());
+}
+
+Status Transport::read(MutableSlice message, const AuthKey &auth_key, PacketInfo *info, MutableSlice *data,
+                       int32 *error_code) {
+  if (message.size() < 8) {
+    if (message.size() == 4) {
+      *error_code = as<int32>(message.begin());
+      return Status::OK();
+    }
+    return Status::Error(PSLICE() << "Invalid mtproto message: smaller than 8 bytes [size=" << message.size() << "]");
+  }
+  info->auth_key_id = as<int64>(message.begin());
+  info->no_crypto_flag = info->auth_key_id == 0;
+  if (info->type == PacketInfo::EndToEnd) {
+    return read_e2e_crypto(message, auth_key, info, data);
+  }
+  if (info->no_crypto_flag) {
+    return read_no_crypto(message, info, data);
+  } else {
+    if (auth_key.empty()) {
+      return Status::Error("Failed to decrypt mtproto message: auth key is empty");
+    }
+    return read_crypto(message, auth_key, info, data);
+  }
+}
+
+size_t Transport::write(const Storer &storer, const AuthKey &auth_key, PacketInfo *info, MutableSlice dest) {
+  if (info->type == PacketInfo::EndToEnd) {
+    return write_e2e_crypto(storer, auth_key, info, dest);
+  }
+  if (info->no_crypto_flag) {
+    return write_no_crypto(storer, info, dest);
+  } else {
+    CHECK(!auth_key.empty());
+    return write_crypto(storer, auth_key, info, dest);
+  }
+}
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/Transport.h b/libs/tdlib/td/td/mtproto/Transport.h
new file mode 100644
index 0000000000..9184d86ecd
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/Transport.h
@@ -0,0 +1,187 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/mtproto/utils.h"
+
+#include "td/utils/common.h"
+#include "td/utils/int_types.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <tuple>
+
+namespace td {
+namespace mtproto {
+class AuthKey;
+
+#pragma pack(push, 4)
+#if TD_MSVC
+#pragma warning(push)
+#pragma warning(disable : 4200)
+#endif
+
+struct CryptoHeader {
+  uint64 auth_key_id;
+  UInt128 message_key;
+
+  // encrypted part
+  uint64 salt;
+  uint64 session_id;
+
+  // It is weird to generate message_id and seq_no while writing a packet.
+  //
+  // uint64 message_id;
+  // uint32 seq_no;
+  // uint32 message_data_length;
+  uint8 data[0];  // use compiler extension
+
+  static size_t encrypted_header_size() {
+    return sizeof(salt) + sizeof(session_id);
+  }
+
+  uint8 *encrypt_begin() {
+    return reinterpret_cast<uint8 *>(&salt);
+  }
+
+  const uint8 *encrypt_begin() const {
+    return reinterpret_cast<const uint8 *>(&salt);
+  }
+
+  CryptoHeader() = delete;
+  CryptoHeader(const CryptoHeader &) = delete;
+  CryptoHeader(CryptoHeader &&) = delete;
+  CryptoHeader &operator=(const CryptoHeader &) = delete;
+  CryptoHeader &operator=(CryptoHeader &&) = delete;
+  ~CryptoHeader() = delete;
+};
+
+struct CryptoPrefix {
+  uint64 message_id;
+  uint32 seq_no;
+  uint32 message_data_length;
+};
+
+struct EndToEndHeader {
+  uint64 auth_key_id;
+  UInt128 message_key;
+
+  // encrypted part
+  // uint32 message_data_length;
+  uint8 data[0];  // use compiler extension
+
+  static size_t encrypted_header_size() {
+    return 0;
+  }
+
+  uint8 *encrypt_begin() {
+    return reinterpret_cast<uint8 *>(&data);
+  }
+
+  const uint8 *encrypt_begin() const {
+    return reinterpret_cast<const uint8 *>(&data);
+  }
+
+  EndToEndHeader() = delete;
+  EndToEndHeader(const EndToEndHeader &) = delete;
+  EndToEndHeader(EndToEndHeader &&) = delete;
+  EndToEndHeader &operator=(const EndToEndHeader &) = delete;
+  EndToEndHeader &operator=(EndToEndHeader &&) = delete;
+  ~EndToEndHeader() = delete;
+};
+
+struct EndToEndPrefix {
+  uint32 message_data_length;
+};
+
+struct NoCryptoHeader {
+  uint64 auth_key_id;
+
+  // message_id is removed from CryptoHeader. Should be removed from here too.
+  //
+  // int64 message_id;
+  // uint32 message_data_length;
+  uint8 data[0];  // use compiler extension
+
+  NoCryptoHeader() = delete;
+  NoCryptoHeader(const NoCryptoHeader &) = delete;
+  NoCryptoHeader(NoCryptoHeader &&) = delete;
+  NoCryptoHeader &operator=(const NoCryptoHeader &) = delete;
+  NoCryptoHeader &operator=(NoCryptoHeader &&) = delete;
+  ~NoCryptoHeader() = delete;
+};
+
+#if TD_MSVC
+#pragma warning(pop)
+#endif
+#pragma pack(pop)
+
+struct PacketInfo {
+  enum { Common, EndToEnd } type = Common;
+  uint64 auth_key_id;
+  uint32 message_ack;
+  UInt128 message_key;
+
+  uint64 salt;
+  uint64 session_id;
+
+  uint64 message_id;
+  int32 seq_no;
+  int32 version = 1;
+  bool no_crypto_flag;
+  bool is_creator = false;
+};
+
+class Transport {
+ public:
+  static Result<uint64> read_auth_key_id(Slice message);
+
+  // Reads mtproto packet from [message] and saves into [data].
+  // If message is encrypted, [auth_key] is used.
+  // Decryption and unpacking is made inplace, so [data] will be subslice of [message].
+  // Returns size of mtproto packet.
+  // If dest.size() >= size, the packet is also written into [dest].
+  // If auth_key is nonempty, encryption will be used.
+  static Status read(MutableSlice message, const AuthKey &auth_key, PacketInfo *info, MutableSlice *data,
+                     int32 *error_code) TD_WARN_UNUSED_RESULT;
+
+  static size_t write(const Storer &storer, const AuthKey &auth_key, PacketInfo *info,
+                      MutableSlice dest = MutableSlice());
+
+ private:
+  template <class HeaderT>
+  static std::tuple<uint32, UInt128> calc_message_ack_and_key(const HeaderT &head, size_t data_size);
+
+  static std::tuple<uint32, UInt128> calc_message_key2(const AuthKey &auth_key, int X, Slice to_encrypt);
+
+  template <class HeaderT>
+  static size_t calc_crypto_size(size_t data_size);
+
+  template <class HeaderT>
+  static size_t calc_crypto_size2(size_t data_size);
+
+  static size_t calc_no_crypto_size(size_t data_size);
+
+  static Status read_no_crypto(MutableSlice message, PacketInfo *info, MutableSlice *data) TD_WARN_UNUSED_RESULT;
+
+  static Status read_crypto(MutableSlice message, const AuthKey &auth_key, PacketInfo *info,
+                            MutableSlice *data) TD_WARN_UNUSED_RESULT;
+  static Status read_e2e_crypto(MutableSlice message, const AuthKey &auth_key, PacketInfo *info,
+                                MutableSlice *data) TD_WARN_UNUSED_RESULT;
+  template <class HeaderT, class PrefixT>
+  static Status read_crypto_impl(int X, MutableSlice message, const AuthKey &auth_key, HeaderT **header_ptr,
+                                 PrefixT **prefix_ptr, MutableSlice *data, PacketInfo *info) TD_WARN_UNUSED_RESULT;
+
+  static size_t write_no_crypto(const Storer &storer, PacketInfo *info, MutableSlice dest);
+
+  static size_t write_crypto(const Storer &storer, const AuthKey &auth_key, PacketInfo *info, MutableSlice dest);
+  static size_t write_e2e_crypto(const Storer &storer, const AuthKey &auth_key, PacketInfo *info, MutableSlice dest);
+  template <class HeaderT>
+  static void write_crypto_impl(int X, const Storer &storer, const AuthKey &auth_key, PacketInfo *info, HeaderT *header,
+                                size_t data_size);
+};
+}  // namespace mtproto
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/crypto.cpp b/libs/tdlib/td/td/mtproto/crypto.cpp
new file mode 100644
index 0000000000..38f7a9b640
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/crypto.cpp
@@ -0,0 +1,441 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/mtproto/crypto.h"
+
+#include "td/mtproto/mtproto_api.h"
+
+#include "td/utils/crypto.h"
+#include "td/utils/int_types.h"  // for UInt256, UInt128, etc
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Random.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/tl_storers.h"
+
+#include <openssl/bio.h>
+#include <openssl/bn.h>
+#include <openssl/pem.h>
+#include <openssl/rsa.h>
+
+#include <cstring>
+
+namespace td {
+
+/*** RSA ***/
+RSA::RSA(BigNum n, BigNum e) : n_(std::move(n)), e_(std::move(e)) {
+  e_.ensure_const_time();
+}
+
+RSA RSA::clone() const {
+  return RSA(n_.clone(), e_.clone());
+}
+
+Result<RSA> RSA::from_pem(Slice pem) {
+  init_crypto();
+
+  auto *bio =
+      BIO_new_mem_buf(const_cast<void *>(static_cast<const void *>(pem.ubegin())), narrow_cast<int32>(pem.size()));
+  if (bio == nullptr) {
+    return Status::Error("Cannot create BIO");
+  }
+  SCOPE_EXIT {
+    BIO_free(bio);
+  };
+
+  auto *rsa = RSA_new();
+  if (rsa == nullptr) {
+    return Status::Error("Cannot create RSA");
+  }
+  SCOPE_EXIT {
+    RSA_free(rsa);
+  };
+
+  if (!PEM_read_bio_RSAPublicKey(bio, &rsa, nullptr, nullptr)) {
+    return Status::Error("Error while reading rsa pubkey");
+  }
+
+  if (RSA_size(rsa) != 256) {
+    return Status::Error("RSA_size != 256");
+  }
+
+  const BIGNUM *n_num;
+  const BIGNUM *e_num;
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
+  n_num = rsa->n;
+  e_num = rsa->e;
+#else
+  RSA_get0_key(rsa, &n_num, &e_num, nullptr);
+#endif
+
+  auto n = static_cast<void *>(BN_dup(n_num));
+  auto e = static_cast<void *>(BN_dup(e_num));
+  if (n == nullptr || e == nullptr) {
+    return Status::Error("Cannot dup BIGNUM");
+  }
+
+  return RSA(BigNum::from_raw(n), BigNum::from_raw(e));
+}
+
+int64 RSA::get_fingerprint() const {
+  mtproto_api::rsa_public_key public_key;
+  // string objects are necessary, because mtproto_api::rsa_public_key contains Slice inside
+  string n_str = n_.to_binary();
+  string e_str = e_.to_binary();
+  public_key.n_ = n_str;
+  public_key.e_ = e_str;
+  size_t size = tl_calc_length(public_key);
+  std::vector<unsigned char> tmp(size);
+  size = tl_store_unsafe(public_key, tmp.data());
+  CHECK(size == tmp.size());
+  unsigned char key_sha1[20];
+  sha1(Slice(tmp.data(), tmp.size()), key_sha1);
+  return as<int64>(key_sha1 + 12);
+}
+
+size_t RSA::size() const {
+  // Checked in RSA::from_pem step
+  return 256;
+}
+
+size_t RSA::encrypt(unsigned char *from, size_t from_len, unsigned char *to) const {
+  CHECK(from_len > 0 && from_len <= 2550);
+  size_t pad = (25500 - from_len - 32) % 255 + 32;
+  size_t chunks = (from_len + pad) / 255;
+  int bits = n_.get_num_bits();
+  CHECK(bits >= 2041 && bits <= 2048);
+  CHECK(chunks * 255 == from_len + pad);
+  Random::secure_bytes(from + from_len, pad);
+
+  BigNumContext ctx;
+  BigNum y;
+  while (chunks-- > 0) {
+    BigNum x = BigNum::from_binary(Slice(from, 255));
+    BigNum::mod_exp(y, x, e_, n_, ctx);
+    string result = y.to_binary(256);
+    std::memcpy(to, result.c_str(), 256);
+    to += 256;
+  }
+  return chunks * 256;
+}
+
+void RSA::decrypt(Slice from, MutableSlice to) const {
+  CHECK(from.size() == 256);
+  BigNumContext ctx;
+  BigNum x = BigNum::from_binary(from);
+  BigNum y;
+  BigNum::mod_exp(y, x, e_, n_, ctx);
+  string result = y.to_binary(256);
+  std::memcpy(to.data(), result.c_str(), 256);
+}
+
+/*** DH ***/
+Status DhHandshake::dh_check(Slice prime_str, const BigNum &prime, int32 g_int, const BigNum &g_a, const BigNum &g_b,
+                             BigNumContext &ctx, DhCallback *callback) {
+  // 2. g generates a cyclic subgroup of prime order (p - 1) / 2, i.e. is a quadratic residue mod p.
+  //    Since g is always equal to 2, 3, 4, 5, 6 or 7, this is easily done using quadratic reciprocity law,
+  //    yielding a simple condition on
+  //    * p mod 4g - namely, p mod 8 = 7 for g = 2; p mod 3 = 2 for g = 3;
+  //    * no extra condition for g = 4;
+  //    * p mod 5 = 1 or 4 for g = 5;
+  //    * p mod 24 = 19 or 23 for g = 6;
+  //    * p mod 7 = 3, 5 or 6 for g = 7.
+
+  bool mod_ok;
+  uint32 mod_r;
+  switch (g_int) {
+    case 2:
+      mod_ok = prime % 8 == 7u;
+      break;
+    case 3:
+      mod_ok = prime % 3 == 2u;
+      break;
+    case 4:
+      mod_ok = true;
+      break;
+    case 5:
+      mod_ok = (mod_r = prime % 5) == 1u || mod_r == 4u;
+      break;
+    case 6:
+      mod_ok = (mod_r = prime % 24) == 19u || mod_r == 23u;
+      break;
+    case 7:
+      mod_ok = (mod_r = prime % 7) == 3u || mod_r == 5u || mod_r == 6u;
+      break;
+    default:
+      mod_ok = false;
+  }
+  if (!mod_ok) {
+    return Status::Error("Bad prime mod 4g");
+  }
+
+  // IMPORTANT: Apart from the conditions on the Diffie-Hellman prime dh_prime and generator g, both sides are
+  // to check that g, g_a and g_b are greater than 1 and less than dh_prime - 1.
+  // We recommend checking that g_a and g_b are between 2^{2048-64} and dh_prime - 2^{2048-64} as well.
+
+  // check that 2^2047 <= p < 2^2048
+  if (prime.get_num_bits() != 2048) {
+    return Status::Error("p is not 2048-bit number");
+  }
+
+  BigNum left;
+  left.set_value(0);
+  left.set_bit(2048 - 64);
+
+  BigNum right;
+  BigNum::sub(right, prime, left);
+
+  if (BigNum::compare(left, g_a) > 0 || BigNum::compare(g_a, right) > 0 || BigNum::compare(left, g_b) > 0 ||
+      BigNum::compare(g_b, right) > 0) {
+    std::string x(2048, '0');
+    std::string y(2048, '0');
+    for (int i = 0; i < 2048; i++) {
+      if (g_a.is_bit_set(i)) {
+        x[i] = '1';
+      }
+      if (g_b.is_bit_set(i)) {
+        y[i] = '1';
+      }
+    }
+    LOG(ERROR) << x;
+    LOG(ERROR) << y;
+    return Status::Error("g^a or g^b is not between 2^{2048-64} and dh_prime - 2^{2048-64}");
+  }
+
+  // check whether p = dh_prime is a safe 2048-bit prime (meaning that both p and (p - 1) / 2 are prime)
+  int is_good_prime = -1;
+  if (callback) {
+    is_good_prime = callback->is_good_prime(prime_str);
+  }
+  if (is_good_prime != -1) {
+    return is_good_prime ? Status::OK() : Status::Error("p or (p - 1) / 2 is not a prime number");
+  }
+  if (!prime.is_prime(ctx)) {
+    if (callback) {
+      callback->add_bad_prime(prime_str);
+    }
+    return Status::Error("p is not a prime number");
+  }
+
+  BigNum half_prime = prime;
+  half_prime -= 1;
+  half_prime /= 2;
+  if (!half_prime.is_prime(ctx)) {
+    if (callback) {
+      callback->add_bad_prime(prime_str);
+    }
+    return Status::Error("(p - 1) / 2 is not a prime number");
+  }
+  if (callback) {
+    callback->add_good_prime(prime_str);
+  }
+
+  // TODO(perf):
+  // Checks:
+  // After g and p have been checked by the client, it makes sense to cache the result,
+  // so as not to repeat lengthy computations in future.
+
+  // If the verification takes too long time (which is the case for older mobile devices),
+  // one might initially run only 15 Miller-Rabin iterations for verifying primeness of p and (p - 1)/2
+  // with error probability not exceeding one billionth, and do more iterations later in the background.
+
+  // Another optimization is to embed into the client application code a small table with some known "good"
+  // couples (g,p) (or just known safe primes p, since the condition on g is easily verified during execution),
+  // checked during code generation phase, so as to avoid doing such verification during runtime altogether.
+  // Server changes these values rarely, thus one usually has to put the current value of server's dh_prime
+  // into such a table. For example, current value of dh_prime equals (in big-endian byte order) ...
+
+  return Status::OK();
+}
+
+int64 dh_auth_key_id(const string &auth_key) {
+  UInt<160> auth_key_sha1;
+  sha1(auth_key, auth_key_sha1.raw);
+  return as<int64>(auth_key_sha1.raw + 12);
+}
+
+void DhHandshake::set_config(int32 g_int, Slice prime_str) {
+  has_config_ = true;
+  prime_ = BigNum::from_binary(prime_str);
+  prime_str_ = prime_str.str();
+
+  b_ = BigNum();
+  g_b_ = BigNum();
+
+  BigNum::random(b_, 2048, -1, 0);
+
+  // g^b
+  g_int_ = g_int;
+  g_.set_value(g_int_);
+
+  BigNum::mod_exp(g_b_, g_, b_, prime_, ctx_);
+}
+
+void DhHandshake::set_g_a_hash(Slice g_a_hash) {
+  has_g_a_hash_ = true;
+  ok_g_a_hash_ = false;
+  CHECK(!has_g_a_);
+  g_a_hash_ = g_a_hash.str();
+}
+
+void DhHandshake::set_g_a(Slice g_a_str) {
+  has_g_a_ = true;
+  if (has_g_a_hash_) {
+    string g_a_hash(32, ' ');
+    sha256(g_a_str, g_a_hash);
+    ok_g_a_hash_ = g_a_hash == g_a_hash_;
+  }
+  g_a_ = BigNum::from_binary(g_a_str);
+}
+
+string DhHandshake::get_g_a() const {
+  CHECK(has_g_a_);
+  return g_a_.to_binary();
+}
+
+string DhHandshake::get_g_b() const {
+  CHECK(has_config_);
+  return g_b_.to_binary();
+}
+string DhHandshake::get_g_b_hash() const {
+  string g_b_hash(32, ' ');
+  sha256(get_g_b(), g_b_hash);
+  return g_b_hash;
+}
+
+Status DhHandshake::run_checks(DhCallback *callback) {
+  CHECK(has_g_a_ && has_config_);
+
+  if (has_g_a_hash_ && !ok_g_a_hash_) {
+    return Status::Error("g_a_hash mismatch");
+  }
+
+  return dh_check(prime_str_, prime_, g_int_, g_a_, g_b_, ctx_, callback);
+}
+
+std::pair<int64, string> DhHandshake::gen_key() {
+  CHECK(has_g_a_ && has_config_);
+  BigNum g_ab;
+  BigNum::mod_exp(g_ab, g_a_, b_, prime_, ctx_);
+  string key = g_ab.to_binary(2048 / 8);
+  auto key_id = calc_key_id(key);
+  return std::pair<int64, string>(key_id, std::move(key));
+}
+
+int64 DhHandshake::calc_key_id(const string &auth_key) {
+  UInt<160> auth_key_sha1;
+  sha1(auth_key, auth_key_sha1.raw);
+  return as<int64>(auth_key_sha1.raw + 12);
+}
+
+Status dh_handshake(int g_int, Slice prime_str, Slice g_a_str, string *g_b_str, string *g_ab_str,
+                    DhCallback *callback) {
+  DhHandshake handshake;
+  handshake.set_config(g_int, prime_str);
+  handshake.set_g_a(g_a_str);
+  TRY_STATUS(handshake.run_checks(callback));
+  *g_b_str = handshake.get_g_b();
+  *g_ab_str = handshake.gen_key().second;
+  return Status::OK();
+}
+
+/*** KDF ***/
+void KDF(const string &auth_key, const UInt128 &msg_key, int X, UInt256 *aes_key, UInt256 *aes_iv) {
+  CHECK(auth_key.size() == 2048 / 8);
+  const char *auth_key_raw = auth_key.c_str();
+  uint8 buf[48];
+  as<UInt128>(buf) = msg_key;
+  as<UInt256>(buf + 16) = as<UInt256>(auth_key_raw + X);
+  uint8 sha1_a[20];
+  sha1(Slice(buf, 48), sha1_a);
+
+  as<UInt128>(buf) = as<UInt128>(auth_key_raw + X + 32);
+  as<UInt128>(buf + 16) = msg_key;
+  as<UInt128>(buf + 32) = as<UInt128>(auth_key_raw + X + 48);
+  uint8 sha1_b[20];
+  sha1(Slice(buf, 48), sha1_b);
+
+  as<UInt256>(buf) = as<UInt256>(auth_key_raw + 64 + X);
+  as<UInt128>(buf + 32) = msg_key;
+  uint8 sha1_c[20];
+  sha1(Slice(buf, 48), sha1_c);
+
+  as<UInt128>(buf) = msg_key;
+  as<UInt256>(buf + 16) = as<UInt256>(auth_key_raw + 96 + X);
+  uint8 sha1_d[20];
+  sha1(Slice(buf, 48), sha1_d);
+
+  as<uint64>(aes_key->raw) = as<uint64>(sha1_a);
+  as<UInt<96>>(aes_key->raw + 8) = as<UInt<96>>(sha1_b + 8);
+  as<UInt<96>>(aes_key->raw + 20) = as<UInt<96>>(sha1_c + 4);
+
+  as<UInt<96>>(aes_iv->raw) = as<UInt<96>>(sha1_a + 8);
+  as<uint64>(aes_iv->raw + 12) = as<uint64>(sha1_b);
+  as<uint32>(aes_iv->raw + 20) = as<uint32>(sha1_c + 16);
+  as<uint64>(aes_iv->raw + 24) = as<uint64>(sha1_d);
+}
+
+void tmp_KDF(const UInt128 &server_nonce, const UInt256 &new_nonce, UInt256 *tmp_aes_key, UInt256 *tmp_aes_iv) {
+  // tmp_aes_key := SHA1(new_nonce + server_nonce) + substr (SHA1(server_nonce + new_nonce), 0, 12);
+  uint8 buf[512 / 8];
+  as<UInt256>(buf) = new_nonce;
+  as<UInt128>(buf + 32) = server_nonce;
+  sha1(Slice(buf, 48), tmp_aes_key->raw);
+
+  as<UInt128>(buf) = server_nonce;
+  as<UInt256>(buf + 16) = new_nonce;
+  uint8 sha1_server_new[20];
+  sha1(Slice(buf, 48), sha1_server_new);
+  as<UInt<96>>(tmp_aes_key->raw + 20) = as<UInt<96>>(sha1_server_new);
+
+  // tmp_aes_iv := substr (SHA1(server_nonce + new_nonce), 12, 8) + SHA1(new_nonce + new_nonce) + substr (new_nonce,
+  // 0,
+  // 4);
+  as<uint64>(tmp_aes_iv->raw) = as<uint64>(sha1_server_new + 12);
+
+  as<UInt256>(buf) = new_nonce;
+  as<UInt256>(buf + 32) = new_nonce;
+  sha1(Slice(buf, 64), tmp_aes_iv->raw + 8);
+  as<uint32>(tmp_aes_iv->raw + 28) = as<uint32>(new_nonce.raw);
+}
+
+// msg_key_large = SHA256 (substr (auth_key, 88+x, 32) + plaintext + random_padding);
+// msg_key = substr (msg_key_large, 8, 16);
+
+void KDF2(Slice auth_key, const UInt128 &msg_key, int X, UInt256 *aes_key, UInt256 *aes_iv) {
+  uint8 buf_raw[36 + 16];
+  MutableSlice buf(buf_raw, 36 + 16);
+  Slice msg_key_slice(msg_key.raw, sizeof(msg_key.raw));
+
+  // sha256_a = SHA256 (msg_key + substr (auth_key, x, 36));
+  buf.copy_from(msg_key_slice);
+  buf.substr(16, 36).copy_from(auth_key.substr(X, 36));
+  uint8 sha256_a_raw[32];
+  MutableSlice sha256_a(sha256_a_raw, 32);
+  sha256(buf, sha256_a);
+
+  // sha256_b = SHA256 (substr (auth_key, 40+x, 36) + msg_key);
+  buf.copy_from(auth_key.substr(40 + X, 36));
+  buf.substr(36).copy_from(msg_key_slice);
+  uint8 sha256_b_raw[32];
+  MutableSlice sha256_b(sha256_b_raw, 32);
+  sha256(buf, sha256_b);
+
+  // aes_key = substr (sha256_a, 0, 8) + substr (sha256_b, 8, 16) + substr (sha256_a, 24, 8);
+  MutableSlice aes_key_slice(aes_key->raw, sizeof(aes_key->raw));
+  aes_key_slice.copy_from(sha256_a.substr(0, 8));
+  aes_key_slice.substr(8).copy_from(sha256_b.substr(8, 16));
+  aes_key_slice.substr(24).copy_from(sha256_a.substr(24, 8));
+
+  // aes_iv = substr (sha256_b, 0, 8) + substr (sha256_a, 8, 16) + substr (sha256_b, 24, 8);
+  MutableSlice aes_iv_slice(aes_iv->raw, sizeof(aes_iv->raw));
+  aes_iv_slice.copy_from(sha256_b.substr(0, 8));
+  aes_iv_slice.substr(8).copy_from(sha256_a.substr(8, 16));
+  aes_iv_slice.substr(24).copy_from(sha256_b.substr(24, 8));
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/crypto.h b/libs/tdlib/td/td/mtproto/crypto.h
new file mode 100644
index 0000000000..1e411c7c73
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/crypto.h
@@ -0,0 +1,160 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/BigNum.h"
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <utility>
+
+namespace td {
+
+/*** RSA ***/
+class RSA {
+ public:
+  RSA clone() const;
+  int64 get_fingerprint() const;
+  size_t size() const;
+  size_t encrypt(unsigned char *from, size_t from_len, unsigned char *to) const;
+
+  void decrypt(Slice from, MutableSlice to) const;
+
+  static Result<RSA> from_pem(Slice pem);
+
+ private:
+  RSA(BigNum n, BigNum e);
+  BigNum n_;
+  BigNum e_;
+};
+
+/*** PublicRsaKeyInterface ***/
+class PublicRsaKeyInterface {
+ public:
+  virtual ~PublicRsaKeyInterface() = default;
+  virtual Result<std::pair<RSA, int64>> get_rsa(const vector<int64> &fingerprints) = 0;
+  virtual void drop_keys() = 0;
+};
+
+/*** DH ***/
+class DhCallback {
+ public:
+  DhCallback() = default;
+  DhCallback(const DhCallback &) = delete;
+  DhCallback &operator=(const DhCallback &) = delete;
+  DhCallback(DhCallback &&) = delete;
+  DhCallback &operator=(DhCallback &&) = delete;
+  virtual ~DhCallback() = default;
+
+  virtual int is_good_prime(Slice prime_str) const = 0;
+  virtual void add_good_prime(Slice prime_str) const = 0;
+  virtual void add_bad_prime(Slice prime_str) const = 0;
+};
+class DhHandshake {
+ public:
+  void set_config(int32 g_int, Slice prime_str);
+
+  bool has_config() const {
+    return has_config_;
+  }
+  void set_g_a_hash(Slice g_a_hash);
+  void set_g_a(Slice g_a_str);
+  bool has_g_a() const {
+    return has_g_a_;
+  }
+  string get_g_a() const;
+  string get_g_b() const;
+  string get_g_b_hash() const;
+  Status run_checks(DhCallback *callback) TD_WARN_UNUSED_RESULT;
+
+  std::pair<int64, string> gen_key();
+
+  static int64 calc_key_id(const string &auth_key);
+
+  enum Flags { HasConfig = 1, HasGA = 2 };
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    auto flags = 0;
+    if (has_config_) {
+      flags |= HasConfig;
+    }
+    if (has_g_a_) {
+      flags |= HasGA;
+    }
+    storer.store_int(flags);
+
+    if (has_config_) {
+      // prime_, prime_str_, b_, g_, g_int_, g_b_
+      storer.store_string(prime_str_);
+      storer.store_string(b_.to_binary());
+      storer.store_int(g_int_);
+      storer.store_string(g_b_.to_binary());
+    }
+    if (has_g_a_) {
+      storer.store_string(g_a_.to_binary());
+    }
+  }
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    auto flags = parser.fetch_int();
+    if (flags & HasConfig) {
+      has_config_ = true;
+    }
+    if (flags & HasGA) {
+      has_g_a_ = true;
+    }
+    if (has_config_) {
+      // prime_, prime_str_, b_, g_, g_int_, g_b_
+      prime_str_ = parser.template fetch_string<std::string>();
+      prime_ = BigNum::from_binary(prime_str_);
+
+      b_ = BigNum::from_binary(parser.template fetch_string<string>());
+
+      g_int_ = parser.fetch_int();
+      g_.set_value(g_int_);
+
+      g_b_ = BigNum::from_binary(parser.template fetch_string<string>());
+    }
+    if (has_g_a_) {
+      g_a_ = BigNum::from_binary(parser.template fetch_string<string>());
+    }
+  }
+
+ private:
+  static Status dh_check(Slice prime_str, const BigNum &prime, int32 g_int, const BigNum &g_a, const BigNum &g_b,
+                         BigNumContext &ctx, DhCallback *callback) TD_WARN_UNUSED_RESULT;
+
+  string prime_str_;
+  BigNum prime_;
+  BigNum g_;
+  int32 g_int_;
+  BigNum b_;
+  BigNum g_b_;
+  BigNum g_a_;
+
+  string g_a_hash_;
+  bool has_g_a_hash_{false};
+  bool ok_g_a_hash_{false};
+
+  bool has_config_ = false;
+  bool has_g_a_ = false;
+
+  BigNumContext ctx_;
+};
+
+// TODO: remove this legacy functions
+Status dh_handshake(int g_int, Slice prime_str, Slice g_a_str, string *g_b_str, string *g_ab_str,
+                    DhCallback *callback) TD_WARN_UNUSED_RESULT;
+int64 dh_auth_key_id(const string &auth_key);
+
+/*** KDF ***/
+void KDF(const string &auth_key, const UInt128 &msg_key, int X, UInt256 *aes_key, UInt256 *aes_iv);
+void tmp_KDF(const UInt128 &server_nonce, const UInt256 &new_nonce, UInt256 *tmp_aes_key, UInt256 *tmp_aes_iv);
+void KDF2(Slice auth_key, const UInt128 &msg_key, int X, UInt256 *aes_key, UInt256 *aes_iv);
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/utils.cpp b/libs/tdlib/td/td/mtproto/utils.cpp
new file mode 100644
index 0000000000..c63a9f32b1
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/utils.cpp
@@ -0,0 +1,33 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/mtproto/utils.h"
+
+#include "td/mtproto/mtproto_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/utils/logging.h"
+
+namespace td {
+
+TLStorer<mtproto_api::Function> create_storer(const mtproto_api::Function &function) {
+  return TLStorer<mtproto_api::Function>(function);
+}
+
+TLStorer<telegram_api::Function> create_storer(const telegram_api::Function &function) {
+  LOG(DEBUG) << "Create storer for " << to_string(function);
+  return TLStorer<telegram_api::Function>(function);
+}
+
+TLObjectStorer<mtproto_api::Object> create_storer(const mtproto_api::Object &object) {
+  return TLObjectStorer<mtproto_api::Object>(object);
+}
+
+TLObjectStorer<telegram_api::Object> create_storer(const telegram_api::Object &object) {
+  return TLObjectStorer<telegram_api::Object>(object);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/mtproto/utils.h b/libs/tdlib/td/td/mtproto/utils.h
new file mode 100644
index 0000000000..9bbb706dfb
--- /dev/null
+++ b/libs/tdlib/td/td/mtproto/utils.h
@@ -0,0 +1,111 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/buffer.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/Storer.h"
+#include "td/utils/tl_parsers.h"
+#include "td/utils/tl_storers.h"
+
+#include <limits>
+
+namespace td {
+
+namespace mtproto {
+struct Query {
+  int64 message_id;
+  int32 seq_no;
+  BufferSlice packet;
+  bool gzip_flag;
+  uint64 invoke_after_id;
+  bool use_quick_ack;
+};
+}  // namespace mtproto
+
+template <class T>
+Result<typename T::ReturnType> fetch_result(Slice message) {
+  TlParser parser(message);
+  auto result = T::fetch_result(parser);
+
+  parser.fetch_end();
+  const char *error = parser.get_error();
+  if (error != nullptr) {
+    LOG(ERROR) << "Can't parse: " << format::as_hex_dump<4>(message);
+    return Status::Error(500, Slice(error));
+  }
+
+  return std::move(result);
+}
+
+template <class T>
+Result<typename T::ReturnType> fetch_result(const BufferSlice &message) {
+  TlBufferParser parser(&message);
+  auto result = T::fetch_result(parser);
+
+  parser.fetch_end();
+  const char *error = parser.get_error();
+  if (error != nullptr) {
+    LOG(ERROR) << "Can't parse: " << format::as_hex_dump<4>(message.as_slice());
+    return Status::Error(500, Slice(error));
+  }
+
+  return std::move(result);
+}
+
+template <class T>
+using TLStorer = DefaultStorer<T>;
+
+template <class T>
+class TLObjectStorer : public Storer {
+  mutable size_t size_ = std::numeric_limits<size_t>::max();
+  const T &object_;
+
+ public:
+  explicit TLObjectStorer(const T &object) : object_(object) {
+  }
+
+  size_t size() const override {
+    if (size_ == std::numeric_limits<size_t>::max()) {
+      TlStorerCalcLength storer;
+      storer.store_binary(object_.get_id());
+      object_.store(storer);
+      size_ = storer.get_length();
+    }
+    return size_;
+  }
+  size_t store(uint8 *ptr) const override {
+    char *p = reinterpret_cast<char *>(ptr);
+    TlStorerUnsafe storer(p);
+    storer.store_binary(object_.get_id());
+    object_.store(storer);
+    return storer.get_buf() - p;
+  }
+};
+
+namespace mtproto_api {
+class Object;
+class Function;
+}  // namespace mtproto_api
+
+namespace telegram_api {
+class Object;
+class Function;
+}  // namespace telegram_api
+
+TLStorer<mtproto_api::Function> create_storer(const mtproto_api::Function &function);
+
+TLStorer<telegram_api::Function> create_storer(const telegram_api::Function &function);
+
+TLObjectStorer<mtproto_api::Object> create_storer(const mtproto_api::Object &object);
+
+TLObjectStorer<telegram_api::Object> create_storer(const telegram_api::Object &object);
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/AccessRights.h b/libs/tdlib/td/td/telegram/AccessRights.h
new file mode 100644
index 0000000000..fd0833ead7
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/AccessRights.h
@@ -0,0 +1,13 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+namespace td {
+
+enum class AccessRights { Read, Edit, Write };
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/AnimationsManager.cpp b/libs/tdlib/td/td/telegram/AnimationsManager.cpp
new file mode 100644
index 0000000000..6a372b1fc4
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/AnimationsManager.cpp
@@ -0,0 +1,695 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/AnimationsManager.h"
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/AuthManager.h"
+#include "td/telegram/DialogId.h"
+#include "td/telegram/DocumentsManager.h"
+#include "td/telegram/files/FileManager.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/logevent/LogEvent.h"
+#include "td/telegram/misc.h"
+#include "td/telegram/Td.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Random.h"
+#include "td/utils/Time.h"
+#include "td/utils/tl_helpers.h"
+
+#include <algorithm>
+
+namespace td {
+
+class GetSavedGifsQuery : public Td::ResultHandler {
+ public:
+  void send(int32 hash) {
+    LOG(INFO) << "Send get saved animations request with hash = " << hash;
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_getSavedGifs(hash))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getSavedGifs>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    td->animations_manager_->on_get_saved_animations(std::move(ptr));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for get saved animations: " << status;
+    td->animations_manager_->on_get_saved_animations_failed(std::move(status));
+  }
+};
+
+class SaveGifQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit SaveGifQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(tl_object_ptr<telegram_api::InputDocument> &&input_document, bool unsave) {
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_saveGif(std::move(input_document), unsave))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_saveGif>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for save gif: " << result;
+    if (!result) {
+      td->animations_manager_->reload_saved_animations(true);
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for save gif: " << status;
+    td->animations_manager_->reload_saved_animations(true);
+    promise_.set_error(std::move(status));
+  }
+};
+
+AnimationsManager::AnimationsManager(Td *td, ActorShared<> parent) : td_(td), parent_(std::move(parent)) {
+  auto limit_string = G()->td_db()->get_binlog_pmc()->get("saved_animations_limit");
+  if (!limit_string.empty()) {
+    auto new_limit = to_integer<int32>(limit_string);
+    if (new_limit > 0) {
+      LOG(DEBUG) << "Load saved animations limit = " << new_limit;
+      saved_animations_limit_ = new_limit;
+    } else {
+      LOG(ERROR) << "Wrong saved animations limit = \"" << limit_string << "\" stored in database";
+    }
+  }
+}
+
+void AnimationsManager::tear_down() {
+  parent_.reset();
+}
+
+int32 AnimationsManager::get_animation_duration(FileId file_id) {
+  auto &animation = animations_[file_id];
+  CHECK(animation != nullptr);
+  return animation->duration;
+}
+
+tl_object_ptr<td_api::animation> AnimationsManager::get_animation_object(FileId file_id, const char *source) {
+  if (!file_id.is_valid()) {
+    return nullptr;
+  }
+
+  auto &animation = animations_[file_id];
+  CHECK(animation != nullptr) << source << " " << file_id << " "
+                              << static_cast<int32>(td_->file_manager_->get_file_view(file_id).get_type());
+  // TODO can we make that function const?
+  animation->is_changed = false;
+  return make_tl_object<td_api::animation>(animation->duration, animation->dimensions.width,
+                                           animation->dimensions.height, animation->file_name, animation->mime_type,
+                                           get_photo_size_object(td_->file_manager_.get(), &animation->thumbnail),
+                                           td_->file_manager_->get_file_object(file_id));
+}
+
+FileId AnimationsManager::on_get_animation(std::unique_ptr<Animation> new_animation, bool replace) {
+  auto file_id = new_animation->file_id;
+  LOG(INFO) << (replace ? "Replace" : "Add") << " animation " << file_id << " of size " << new_animation->dimensions;
+  auto &a = animations_[file_id];
+  if (a == nullptr) {
+    a = std::move(new_animation);
+  } else if (replace) {
+    CHECK(a->file_id == file_id);
+    if (a->mime_type != new_animation->mime_type) {
+      LOG(DEBUG) << "Animation " << file_id << " info has changed";
+      a->mime_type = new_animation->mime_type;
+      a->is_changed = true;
+    }
+    if (a->file_name != new_animation->file_name) {
+      LOG(DEBUG) << "Animation " << file_id << " file name has changed";
+      a->file_name = std::move(new_animation->file_name);
+      a->is_changed = true;
+    }
+    if (a->dimensions != new_animation->dimensions) {
+      LOG(DEBUG) << "Animation " << file_id << " dimensions has changed";
+      a->dimensions = new_animation->dimensions;
+      a->is_changed = true;
+    }
+    if (a->duration != new_animation->duration) {
+      LOG(DEBUG) << "Animation " << file_id << " duration has changed";
+      a->duration = new_animation->duration;
+      a->is_changed = true;
+    }
+    if (a->thumbnail != new_animation->thumbnail) {
+      if (!a->thumbnail.file_id.is_valid()) {
+        LOG(DEBUG) << "Animation " << file_id << " thumbnail has changed";
+      } else {
+        LOG(INFO) << "Animation " << file_id << " thumbnail has changed from " << a->thumbnail << " to "
+                  << new_animation->thumbnail;
+      }
+      a->thumbnail = new_animation->thumbnail;
+      a->is_changed = true;
+    }
+  }
+
+  return file_id;
+}
+
+const AnimationsManager::Animation *AnimationsManager::get_animation(FileId file_id) const {
+  auto animation = animations_.find(file_id);
+  if (animation == animations_.end()) {
+    return nullptr;
+  }
+
+  CHECK(animation->second->file_id == file_id);
+  return animation->second.get();
+}
+
+FileId AnimationsManager::get_animation_thumbnail_file_id(FileId file_id) const {
+  auto animation = get_animation(file_id);
+  CHECK(animation != nullptr);
+  return animation->thumbnail.file_id;
+}
+
+void AnimationsManager::delete_animation_thumbnail(FileId file_id) {
+  auto &animation = animations_[file_id];
+  CHECK(animation != nullptr);
+  animation->thumbnail = PhotoSize();
+}
+
+FileId AnimationsManager::dup_animation(FileId new_id, FileId old_id) {
+  LOG(INFO) << "Dup animation " << old_id << " to " << new_id;
+  const Animation *old_animation = get_animation(old_id);
+  CHECK(old_animation != nullptr);
+  auto &new_animation = animations_[new_id];
+  CHECK(!new_animation);
+  new_animation = std::make_unique<Animation>(*old_animation);
+  new_animation->file_id = new_id;
+  new_animation->thumbnail.file_id = td_->file_manager_->dup_file_id(new_animation->thumbnail.file_id);
+  return new_id;
+}
+
+bool AnimationsManager::merge_animations(FileId new_id, FileId old_id, bool can_delete_old) {
+  if (!old_id.is_valid()) {
+    LOG(ERROR) << "Old file id is invalid";
+    return true;
+  }
+
+  LOG(INFO) << "Merge animations " << new_id << " and " << old_id;
+  const Animation *old_ = get_animation(old_id);
+  CHECK(old_ != nullptr);
+  if (old_id == new_id) {
+    return old_->is_changed;
+  }
+
+  auto new_it = animations_.find(new_id);
+  if (new_it == animations_.end()) {
+    auto &old = animations_[old_id];
+    old->is_changed = true;
+    if (!can_delete_old) {
+      dup_animation(new_id, old_id);
+    } else {
+      old->file_id = new_id;
+      animations_.emplace(new_id, std::move(old));
+    }
+  } else {
+    Animation *new_ = new_it->second.get();
+    CHECK(new_ != nullptr);
+
+    new_->is_changed = true;
+    if (old_->thumbnail != new_->thumbnail) {
+      //    LOG_STATUS(td_->file_manager_->merge(new_->thumbnail.file_id, old_->thumbnail.file_id));
+    }
+  }
+  LOG_STATUS(td_->file_manager_->merge(new_id, old_id));
+  if (can_delete_old) {
+    animations_.erase(old_id);
+  }
+  return true;
+}
+
+void AnimationsManager::create_animation(FileId file_id, PhotoSize thumbnail, string file_name, string mime_type,
+                                         int32 duration, Dimensions dimensions, bool replace) {
+  auto a = make_unique<Animation>();
+  a->file_id = file_id;
+  a->file_name = std::move(file_name);
+  a->mime_type = std::move(mime_type);
+  a->duration = max(duration, 0);
+  a->dimensions = dimensions;
+  a->thumbnail = std::move(thumbnail);
+  on_get_animation(std::move(a), replace);
+}
+
+tl_object_ptr<telegram_api::InputMedia> AnimationsManager::get_input_media(
+    FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file,
+    tl_object_ptr<telegram_api::InputFile> input_thumbnail) const {
+  auto file_view = td_->file_manager_->get_file_view(file_id);
+  if (file_view.is_encrypted()) {
+    return nullptr;
+  }
+  if (file_view.has_remote_location() && !file_view.remote_location().is_web()) {
+    return make_tl_object<telegram_api::inputMediaDocument>(0, file_view.remote_location().as_input_document(), 0);
+  }
+  if (file_view.has_url()) {
+    return make_tl_object<telegram_api::inputMediaDocumentExternal>(0, file_view.url(), 0);
+  }
+  CHECK(!file_view.has_remote_location());
+
+  if (input_file) {
+    const Animation *animation = get_animation(file_id);
+    CHECK(animation != nullptr);
+
+    vector<tl_object_ptr<telegram_api::DocumentAttribute>> attributes;
+    if (!animation->file_name.empty()) {
+      attributes.push_back(make_tl_object<telegram_api::documentAttributeFilename>(animation->file_name));
+    }
+    string mime_type = animation->mime_type;
+    if (animation->mime_type == "video/mp4") {
+      attributes.push_back(make_tl_object<telegram_api::documentAttributeVideo>(
+          0, false /*ignored*/, false /*ignored*/, animation->duration, animation->dimensions.width,
+          animation->dimensions.height));
+    } else if (animation->dimensions.width != 0 && animation->dimensions.height != 0) {
+      if (!begins_with(mime_type, "image/")) {
+        mime_type = "image/gif";
+      }
+      attributes.push_back(make_tl_object<telegram_api::documentAttributeImageSize>(animation->dimensions.width,
+                                                                                    animation->dimensions.height));
+    }
+    int32 flags = 0;
+    if (input_thumbnail != nullptr) {
+      flags |= telegram_api::inputMediaUploadedDocument::THUMB_MASK;
+    }
+    return make_tl_object<telegram_api::inputMediaUploadedDocument>(
+        flags, false /*ignored*/, std::move(input_file), std::move(input_thumbnail), mime_type, std::move(attributes),
+        vector<tl_object_ptr<telegram_api::InputDocument>>(), 0);
+  }
+
+  return nullptr;
+}
+SecretInputMedia AnimationsManager::get_secret_input_media(FileId animation_file_id,
+                                                           tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                                           const string &caption, BufferSlice thumbnail) const {
+  auto *animation = get_animation(animation_file_id);
+  CHECK(animation != nullptr);
+  auto file_view = td_->file_manager_->get_file_view(animation_file_id);
+  auto &encryption_key = file_view.encryption_key();
+  if (encryption_key.empty()) {
+    return SecretInputMedia{};
+  }
+  if (file_view.has_remote_location()) {
+    input_file = file_view.remote_location().as_input_encrypted_file();
+  }
+  if (!input_file) {
+    return SecretInputMedia{};
+  }
+  if (animation->thumbnail.file_id.is_valid() && thumbnail.empty()) {
+    return SecretInputMedia{};
+  }
+  vector<tl_object_ptr<secret_api::DocumentAttribute>> attributes;
+  if (!animation->file_name.empty()) {
+    attributes.push_back(make_tl_object<secret_api::documentAttributeFilename>(animation->file_name));
+  }
+  if (animation->duration != 0 && animation->mime_type == "video/mp4") {
+    attributes.push_back(make_tl_object<secret_api::documentAttributeVideo>(
+        animation->duration, animation->dimensions.width, animation->dimensions.height));
+  }
+  if (animation->dimensions.width != 0 && animation->dimensions.height != 0) {
+    attributes.push_back(make_tl_object<secret_api::documentAttributeImageSize>(animation->dimensions.width,
+                                                                                animation->dimensions.height));
+  }
+  attributes.push_back(make_tl_object<secret_api::documentAttributeAnimated>());
+
+  return SecretInputMedia{
+      std::move(input_file),
+      make_tl_object<secret_api::decryptedMessageMediaDocument>(
+          std::move(thumbnail), animation->thumbnail.dimensions.width, animation->thumbnail.dimensions.height,
+          animation->mime_type, narrow_cast<int32>(file_view.size()), BufferSlice(encryption_key.key_slice()),
+          BufferSlice(encryption_key.iv_slice()), std::move(attributes), caption)};
+}
+
+void AnimationsManager::on_update_saved_animations_limit(int32 saved_animations_limit) {
+  if (saved_animations_limit != saved_animations_limit_) {
+    if (saved_animations_limit > 0) {
+      LOG(INFO) << "Update saved animations limit to " << saved_animations_limit;
+      G()->td_db()->get_binlog_pmc()->set("saved_animations_limit", to_string(saved_animations_limit));
+      saved_animations_limit_ = saved_animations_limit;
+      if (static_cast<int32>(saved_animation_ids_.size()) > saved_animations_limit_) {
+        saved_animation_ids_.resize(saved_animations_limit_);
+        send_update_saved_animations();
+      }
+    } else {
+      LOG(ERROR) << "Receive wrong saved animations limit = " << saved_animations_limit;
+    }
+  }
+}
+
+class AnimationsManager::AnimationListLogEvent {
+ public:
+  vector<FileId> animation_ids;
+
+  AnimationListLogEvent() = default;
+
+  explicit AnimationListLogEvent(vector<FileId> animation_ids) : animation_ids(std::move(animation_ids)) {
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    AnimationsManager *animations_manager = storer.context()->td().get_actor_unsafe()->animations_manager_.get();
+    td::store(narrow_cast<int32>(animation_ids.size()), storer);
+    for (auto animation_id : animation_ids) {
+      animations_manager->store_animation(animation_id, storer);
+    }
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    AnimationsManager *animations_manager = parser.context()->td().get_actor_unsafe()->animations_manager_.get();
+    int32 size = parser.fetch_int();
+    animation_ids.resize(size);
+    for (auto &animation_id : animation_ids) {
+      animation_id = animations_manager->parse_animation(parser);
+    }
+  }
+};
+
+void AnimationsManager::reload_saved_animations(bool force) {
+  if (!td_->auth_manager_->is_bot() && next_saved_animations_load_time_ >= 0 &&
+      (next_saved_animations_load_time_ < Time::now() || force)) {
+    LOG_IF(INFO, force) << "Reload saved animations";
+    next_saved_animations_load_time_ = -1;
+    td_->create_handler<GetSavedGifsQuery>()->send(get_saved_animations_hash());
+  }
+}
+
+vector<FileId> AnimationsManager::get_saved_animations(Promise<Unit> &&promise) {
+  if (!are_saved_animations_loaded_) {
+    load_saved_animations(std::move(promise));
+    return {};
+  }
+  reload_saved_animations(false);
+
+  promise.set_value(Unit());
+  return saved_animation_ids_;
+}
+
+void AnimationsManager::load_saved_animations(Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    are_saved_animations_loaded_ = true;
+  }
+  if (are_saved_animations_loaded_) {
+    promise.set_value(Unit());
+    return;
+  }
+  load_saved_animations_queries_.push_back(std::move(promise));
+  if (load_saved_animations_queries_.size() == 1u) {
+    if (G()->parameters().use_file_db) {  // otherwise there is no sqlite_pmc, TODO
+      LOG(INFO) << "Trying to load saved animations from database";
+      G()->td_db()->get_sqlite_pmc()->get("ans", PromiseCreator::lambda([](string value) {
+                                            send_closure(G()->animations_manager(),
+                                                         &AnimationsManager::on_load_saved_animations_from_database,
+                                                         std::move(value));
+                                          }));
+    } else {
+      LOG(INFO) << "Trying to load saved animations from server";
+      reload_saved_animations(true);
+    }
+  }
+}
+
+void AnimationsManager::on_load_saved_animations_from_database(const string &value) {
+  if (value.empty()) {
+    LOG(INFO) << "Saved animations aren't found in database";
+    reload_saved_animations(true);
+    return;
+  }
+
+  LOG(INFO) << "Successfully loaded saved animations list of size " << value.size() << " from database";
+
+  AnimationListLogEvent log_event;
+  log_event_parse(log_event, value).ensure();
+
+  on_load_saved_animations_finished(std::move(log_event.animation_ids), true);
+}
+
+void AnimationsManager::on_load_saved_animations_finished(vector<FileId> &&saved_animation_ids, bool from_database) {
+  if (static_cast<int32>(saved_animation_ids.size()) > saved_animations_limit_) {
+    saved_animation_ids.resize(saved_animations_limit_);
+  }
+  saved_animation_ids_ = std::move(saved_animation_ids);
+  are_saved_animations_loaded_ = true;
+  send_update_saved_animations(from_database);
+  auto promises = std::move(load_saved_animations_queries_);
+  load_saved_animations_queries_.clear();
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+void AnimationsManager::on_get_saved_animations(
+    tl_object_ptr<telegram_api::messages_SavedGifs> &&saved_animations_ptr) {
+  CHECK(!td_->auth_manager_->is_bot());
+  next_saved_animations_load_time_ = Time::now_cached() + Random::fast(30 * 60, 50 * 60);
+
+  CHECK(saved_animations_ptr != nullptr);
+  int32 constructor_id = saved_animations_ptr->get_id();
+  if (constructor_id == telegram_api::messages_savedGifsNotModified::ID) {
+    LOG(INFO) << "Saved animations are not modified";
+    return;
+  }
+  CHECK(constructor_id == telegram_api::messages_savedGifs::ID);
+  auto saved_animations = move_tl_object_as<telegram_api::messages_savedGifs>(saved_animations_ptr);
+  LOG(INFO) << "Receive " << saved_animations->gifs_.size() << " saved animations from server";
+
+  vector<FileId> saved_animation_ids;
+  saved_animation_ids.reserve(saved_animations->gifs_.size());
+  for (auto &document_ptr : saved_animations->gifs_) {
+    int32 document_constructor_id = document_ptr->get_id();
+    if (document_constructor_id == telegram_api::documentEmpty::ID) {
+      LOG(ERROR) << "Empty gif document received";
+      continue;
+    }
+    CHECK(document_constructor_id == telegram_api::document::ID);
+    auto document =
+        td_->documents_manager_->on_get_document(move_tl_object_as<telegram_api::document>(document_ptr), DialogId());
+    if (document.first != DocumentsManager::DocumentType::Animation) {
+      LOG(ERROR) << "Receive " << static_cast<int>(document.first) << " instead of animation as saved animation";
+      continue;
+    }
+    saved_animation_ids.push_back(document.second);
+  }
+
+  on_load_saved_animations_finished(std::move(saved_animation_ids));
+
+  LOG_IF(ERROR, get_saved_animations_hash() != saved_animations->hash_)
+      << "Saved animations hash mismatch: " << saved_animations->hash_ << " vs " << get_saved_animations_hash();
+}
+
+void AnimationsManager::on_get_saved_animations_failed(Status error) {
+  CHECK(error.is_error());
+  next_saved_animations_load_time_ = Time::now_cached() + Random::fast(5, 10);
+  auto promises = std::move(load_saved_animations_queries_);
+  load_saved_animations_queries_.clear();
+  for (auto &promise : promises) {
+    promise.set_error(error.clone());
+  }
+}
+
+int32 AnimationsManager::get_saved_animations_hash() const {
+  vector<uint32> numbers;
+  numbers.reserve(saved_animation_ids_.size() * 2);
+  for (auto animation_id : saved_animation_ids_) {
+    auto animation = get_animation(animation_id);
+    CHECK(animation != nullptr);
+    auto file_view = td_->file_manager_->get_file_view(animation_id);
+    CHECK(file_view.has_remote_location());
+    CHECK(!file_view.remote_location().is_encrypted());
+    CHECK(!file_view.remote_location().is_web());
+    auto id = static_cast<uint64>(file_view.remote_location().get_id());
+    numbers.push_back(static_cast<uint32>(id >> 32));
+    numbers.push_back(static_cast<uint32>(id & 0xFFFFFFFF));
+  }
+  return get_vector_hash(numbers);
+}
+
+void AnimationsManager::add_saved_animation(const tl_object_ptr<td_api::InputFile> &input_file,
+                                            Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(7, "Method is not available for bots"));
+  }
+  if (!are_saved_animations_loaded_) {
+    load_saved_animations(std::move(promise));
+    return;
+  }
+
+  auto r_file_id = td_->file_manager_->get_input_file_id(FileType::Animation, input_file, DialogId(), false, false);
+  if (r_file_id.is_error()) {
+    return promise.set_error(Status::Error(7, r_file_id.error().message()));  // TODO do not drop error code
+  }
+
+  add_saved_animation_inner(r_file_id.ok(), std::move(promise));
+}
+
+void AnimationsManager::add_saved_animation_inner(FileId animation_id, Promise<Unit> &&promise) {
+  if (add_saved_animation_impl(animation_id, promise)) {
+    // TODO invokeAfter and log event
+    auto file_view = td_->file_manager_->get_file_view(animation_id);
+    td_->create_handler<SaveGifQuery>(std::move(promise))->send(file_view.remote_location().as_input_document(), false);
+  }
+}
+
+void AnimationsManager::add_saved_animation_by_id(FileId animation_id) {
+  // TODO log event
+  Promise<Unit> promise;
+  add_saved_animation_impl(animation_id, promise);
+}
+
+bool AnimationsManager::add_saved_animation_impl(FileId animation_id, Promise<Unit> &promise) {
+  CHECK(!td_->auth_manager_->is_bot());
+
+  if (!are_saved_animations_loaded_) {
+    load_saved_animations(PromiseCreator::lambda([animation_id, promise = std::move(promise)](Result<> result) mutable {
+      if (result.is_ok()) {
+        send_closure(G()->animations_manager(), &AnimationsManager::add_saved_animation_inner, animation_id,
+                     std::move(promise));
+      } else {
+        promise.set_error(result.move_as_error());
+      }
+    }));
+    return false;
+  }
+
+  if (!saved_animation_ids_.empty() && saved_animation_ids_[0] == animation_id) {
+    if (saved_animation_ids_[0].get_remote() == 0 && animation_id.get_remote() != 0) {
+      saved_animation_ids_[0] = animation_id;
+      save_saved_animations_to_database();
+    }
+
+    promise.set_value(Unit());
+    return false;
+  }
+
+  auto animation = get_animation(animation_id);
+  if (animation == nullptr) {
+    promise.set_error(Status::Error(7, "Animation not found"));
+    return false;
+  }
+  if (animation->mime_type != "video/mp4") {
+    promise.set_error(Status::Error(7, "Only MPEG4 animations can be saved"));
+    return false;
+  }
+
+  auto file_view = td_->file_manager_->get_file_view(animation_id);
+  if (!file_view.has_remote_location()) {
+    promise.set_error(Status::Error(7, "Can save only sent animations"));
+    return false;
+  }
+  if (file_view.remote_location().is_encrypted()) {
+    promise.set_error(Status::Error(7, "Can't save encrypted animations"));
+    return false;
+  }
+  if (file_view.remote_location().is_web()) {
+    promise.set_error(Status::Error(7, "Can't save web animations"));
+    return false;
+  }
+
+  auto it = std::find(saved_animation_ids_.begin(), saved_animation_ids_.end(), animation_id);
+  if (it == saved_animation_ids_.end()) {
+    if (static_cast<int32>(saved_animation_ids_.size()) == saved_animations_limit_) {
+      saved_animation_ids_.back() = animation_id;
+    } else {
+      saved_animation_ids_.push_back(animation_id);
+    }
+    it = saved_animation_ids_.end() - 1;
+  }
+  std::rotate(saved_animation_ids_.begin(), it, it + 1);
+  if (saved_animation_ids_[0].get_remote() == 0 && animation_id.get_remote() != 0) {
+    saved_animation_ids_[0] = animation_id;
+  }
+
+  send_update_saved_animations();
+  return true;
+}
+
+void AnimationsManager::remove_saved_animation(const tl_object_ptr<td_api::InputFile> &input_file,
+                                               Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(7, "Method is not available for bots"));
+  }
+  if (!are_saved_animations_loaded_) {
+    load_saved_animations(std::move(promise));
+    return;
+  }
+
+  auto r_file_id = td_->file_manager_->get_input_file_id(FileType::Animation, input_file, DialogId(), false, false);
+  if (r_file_id.is_error()) {
+    return promise.set_error(Status::Error(7, r_file_id.error().message()));  // TODO do not drop error code
+  }
+
+  FileId file_id = r_file_id.ok();
+  auto it = std::find(saved_animation_ids_.begin(), saved_animation_ids_.end(), file_id);
+  if (it == saved_animation_ids_.end()) {
+    return promise.set_value(Unit());
+  }
+
+  auto animation = get_animation(file_id);
+  if (animation == nullptr) {
+    return promise.set_error(Status::Error(7, "Animation not found"));
+  }
+
+  // TODO invokeAfter
+  auto file_view = td_->file_manager_->get_file_view(file_id);
+  CHECK(file_view.has_remote_location());
+  CHECK(!file_view.remote_location().is_encrypted());
+  CHECK(!file_view.remote_location().is_web());
+  td_->create_handler<SaveGifQuery>(std::move(promise))->send(file_view.remote_location().as_input_document(), true);
+
+  saved_animation_ids_.erase(it);
+
+  send_update_saved_animations();
+}
+
+void AnimationsManager::send_update_saved_animations(bool from_database) {
+  if (are_saved_animations_loaded_) {
+    vector<int32> animations;
+    animations.reserve(saved_animation_ids_.size());
+    for (auto animation_id : saved_animation_ids_) {
+      animations.push_back(animation_id.get());
+    }
+    send_closure(G()->td(), &Td::send_update, make_tl_object<td_api::updateSavedAnimations>(std::move(animations)));
+
+    if (!from_database) {
+      save_saved_animations_to_database();
+    }
+  }
+}
+
+void AnimationsManager::save_saved_animations_to_database() {
+  if (G()->parameters().use_file_db) {
+    LOG(INFO) << "Save saved animations to database";
+    AnimationListLogEvent log_event(saved_animation_ids_);
+    G()->td_db()->get_sqlite_pmc()->set("ans", log_event_store(log_event).as_slice().str(), Auto());
+  }
+}
+
+string AnimationsManager::get_animation_search_text(FileId file_id) const {
+  auto animation = get_animation(file_id);
+  CHECK(animation != nullptr);
+  return animation->file_name;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/AnimationsManager.h b/libs/tdlib/td/td/telegram/AnimationsManager.h
new file mode 100644
index 0000000000..3282d70521
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/AnimationsManager.h
@@ -0,0 +1,133 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/actor.h"
+
+#include "td/telegram/files/FileId.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/SecretInputMedia.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/Status.h"
+
+#include <unordered_map>
+
+namespace td {
+class Td;
+template <class T>
+class Promise;
+}  // namespace td
+
+namespace td {
+
+class AnimationsManager : public Actor {
+ public:
+  AnimationsManager(Td *td, ActorShared<> parent);
+
+  int32 get_animation_duration(FileId file_id);
+
+  tl_object_ptr<td_api::animation> get_animation_object(FileId file_id, const char *source);
+
+  void create_animation(FileId file_id, PhotoSize thumbnail, string file_name, string mime_type, int32 duration,
+                        Dimensions dimensions, bool replace);
+
+  tl_object_ptr<telegram_api::InputMedia> get_input_media(FileId file_id,
+                                                          tl_object_ptr<telegram_api::InputFile> input_file,
+                                                          tl_object_ptr<telegram_api::InputFile> input_thumbnail) const;
+
+  SecretInputMedia get_secret_input_media(FileId animation_file_id,
+                                          tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                          const string &caption, BufferSlice thumbnail) const;
+
+  FileId get_animation_thumbnail_file_id(FileId file_id) const;
+
+  void delete_animation_thumbnail(FileId file_id);
+
+  FileId dup_animation(FileId new_id, FileId old_id);
+
+  bool merge_animations(FileId new_id, FileId old_id, bool can_delete_old);
+
+  void on_update_saved_animations_limit(int32 saved_animations_limit);
+
+  void reload_saved_animations(bool force);
+
+  void on_get_saved_animations(tl_object_ptr<telegram_api::messages_SavedGifs> &&saved_animations_ptr);
+
+  void on_get_saved_animations_failed(Status error);
+
+  vector<FileId> get_saved_animations(Promise<Unit> &&promise);
+
+  void add_saved_animation(const tl_object_ptr<td_api::InputFile> &input_file, Promise<Unit> &&promise);
+
+  void add_saved_animation_by_id(FileId animation_id);
+
+  void remove_saved_animation(const tl_object_ptr<td_api::InputFile> &input_file, Promise<Unit> &&promise);
+
+  template <class T>
+  void store_animation(FileId file_id, T &storer) const;
+
+  template <class T>
+  FileId parse_animation(T &parser);
+
+  string get_animation_search_text(FileId file_id) const;
+
+ private:
+  class Animation {
+   public:
+    string file_name;
+    string mime_type;
+    int32 duration = 0;
+    Dimensions dimensions;
+    PhotoSize thumbnail;
+
+    FileId file_id;
+
+    bool is_changed = true;
+  };
+
+  const Animation *get_animation(FileId file_id) const;
+
+  FileId on_get_animation(std::unique_ptr<Animation> new_animation, bool replace);
+
+  int32 get_saved_animations_hash() const;
+
+  void add_saved_animation_inner(FileId animation_id, Promise<Unit> &&promise);
+
+  bool add_saved_animation_impl(FileId animation_id, Promise<Unit> &promise);
+
+  void load_saved_animations(Promise<Unit> &&promise);
+
+  void on_load_saved_animations_from_database(const string &value);
+
+  void on_load_saved_animations_finished(vector<FileId> &&saved_animation_ids, bool from_database = false);
+
+  void send_update_saved_animations(bool from_database = false);
+
+  void save_saved_animations_to_database();
+
+  void tear_down() override;
+
+  class AnimationListLogEvent;
+
+  Td *td_;
+  ActorShared<> parent_;
+
+  std::unordered_map<FileId, unique_ptr<Animation>, FileIdHash> animations_;
+
+  int32 saved_animations_limit_ = 200;
+  vector<FileId> saved_animation_ids_;
+  double next_saved_animations_load_time_ = 0;
+  bool are_saved_animations_loaded_ = false;
+  vector<Promise<Unit>> load_saved_animations_queries_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/AnimationsManager.hpp b/libs/tdlib/td/td/telegram/AnimationsManager.hpp
new file mode 100644
index 0000000000..1e45039333
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/AnimationsManager.hpp
@@ -0,0 +1,46 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/telegram/AnimationsManager.h"
+
+#include "td/telegram/files/FileId.hpp"
+#include "td/telegram/Photo.hpp"
+#include "td/telegram/Version.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+
+template <class T>
+void AnimationsManager::store_animation(FileId file_id, T &storer) const {
+  auto it = animations_.find(file_id);
+  CHECK(it != animations_.end());
+  const Animation *animation = it->second.get();
+  store(animation->duration, storer);
+  store(animation->dimensions, storer);
+  store(animation->file_name, storer);
+  store(animation->mime_type, storer);
+  store(animation->thumbnail, storer);
+  store(file_id, storer);
+}
+
+template <class T>
+FileId AnimationsManager::parse_animation(T &parser) {
+  auto animation = make_unique<Animation>();
+  if (parser.version() >= static_cast<int32>(Version::AddDurationToAnimation)) {
+    parse(animation->duration, parser);
+  }
+  parse(animation->dimensions, parser);
+  parse(animation->file_name, parser);
+  parse(animation->mime_type, parser);
+  parse(animation->thumbnail, parser);
+  parse(animation->file_id, parser);
+  return on_get_animation(std::move(animation), false);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/AudiosManager.cpp b/libs/tdlib/td/td/telegram/AudiosManager.cpp
new file mode 100644
index 0000000000..248ea17e7b
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/AudiosManager.cpp
@@ -0,0 +1,260 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/AudiosManager.h"
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/DocumentsManager.h"
+#include "td/telegram/files/FileManager.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/Td.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+AudiosManager::AudiosManager(Td *td) : td_(td) {
+}
+
+int32 AudiosManager::get_audio_duration(FileId file_id) {
+  auto &audio = audios_[file_id];
+  CHECK(audio != nullptr);
+  return audio->duration;
+}
+
+tl_object_ptr<td_api::audio> AudiosManager::get_audio_object(FileId file_id) {
+  if (!file_id.is_valid()) {
+    return nullptr;
+  }
+
+  auto &audio = audios_[file_id];
+  CHECK(audio != nullptr);
+  audio->is_changed = false;
+  return make_tl_object<td_api::audio>(
+      audio->duration, audio->title, audio->performer, audio->file_name, audio->mime_type,
+      get_photo_size_object(td_->file_manager_.get(), &audio->thumbnail), td_->file_manager_->get_file_object(file_id));
+}
+
+FileId AudiosManager::on_get_audio(std::unique_ptr<Audio> new_audio, bool replace) {
+  auto file_id = new_audio->file_id;
+  LOG(INFO) << "Receive audio " << file_id;
+  auto &a = audios_[file_id];
+  if (a == nullptr) {
+    a = std::move(new_audio);
+  } else if (replace) {
+    CHECK(a->file_id == new_audio->file_id);
+    if (a->mime_type != new_audio->mime_type) {
+      LOG(DEBUG) << "Audio " << file_id << " info has changed";
+      a->mime_type = new_audio->mime_type;
+      a->is_changed = true;
+    }
+    if (a->duration != new_audio->duration || a->title != new_audio->title || a->performer != new_audio->performer) {
+      LOG(DEBUG) << "Audio " << file_id << " info has changed";
+      a->duration = new_audio->duration;
+      a->title = new_audio->title;
+      a->performer = new_audio->performer;
+      a->is_changed = true;
+    }
+    if (a->file_name != new_audio->file_name) {
+      LOG(DEBUG) << "Audio " << file_id << " file name has changed";
+      a->file_name = std::move(new_audio->file_name);
+      a->is_changed = true;
+    }
+    if (a->thumbnail != new_audio->thumbnail) {
+      if (!a->thumbnail.file_id.is_valid()) {
+        LOG(DEBUG) << "Audio " << file_id << " thumbnail has changed";
+      } else {
+        LOG(INFO) << "Audio " << file_id << " thumbnail has changed from " << a->thumbnail << " to "
+                  << new_audio->thumbnail;
+      }
+      a->thumbnail = new_audio->thumbnail;
+      a->is_changed = true;
+    }
+  }
+
+  return file_id;
+}
+
+const AudiosManager::Audio *AudiosManager::get_audio(FileId file_id) const {
+  auto audio = audios_.find(file_id);
+  if (audio == audios_.end()) {
+    return nullptr;
+  }
+
+  CHECK(audio->second->file_id == file_id);
+  return audio->second.get();
+}
+
+FileId AudiosManager::dup_audio(FileId new_id, FileId old_id) {
+  const Audio *old_audio = get_audio(old_id);
+  CHECK(old_audio != nullptr);
+  auto &new_audio = audios_[new_id];
+  CHECK(!new_audio);
+  new_audio = std::make_unique<Audio>(*old_audio);
+  new_audio->file_id = new_id;
+  new_audio->thumbnail.file_id = td_->file_manager_->dup_file_id(new_audio->thumbnail.file_id);
+  return new_id;
+}
+
+bool AudiosManager::merge_audios(FileId new_id, FileId old_id, bool can_delete_old) {
+  if (!old_id.is_valid()) {
+    LOG(ERROR) << "Old file id is invalid";
+    return true;
+  }
+
+  LOG(INFO) << "Merge audios " << new_id << " and " << old_id;
+  const Audio *old_ = get_audio(old_id);
+  CHECK(old_ != nullptr);
+  if (old_id == new_id) {
+    return old_->is_changed;
+  }
+
+  auto new_it = audios_.find(new_id);
+  if (new_it == audios_.end()) {
+    auto &old = audios_[old_id];
+    old->is_changed = true;
+    if (!can_delete_old) {
+      dup_audio(new_id, old_id);
+    } else {
+      old->file_id = new_id;
+      audios_.emplace(new_id, std::move(old));
+    }
+  } else {
+    Audio *new_ = new_it->second.get();
+    CHECK(new_ != nullptr);
+
+    if (!old_->mime_type.empty() && old_->mime_type != new_->mime_type) {
+      LOG(INFO) << "Audio has changed: mime_type = (" << old_->mime_type << ", " << new_->mime_type << ")";
+    }
+
+    new_->is_changed = true;
+    if (old_->thumbnail != new_->thumbnail) {
+      //    LOG_STATUS(td_->file_manager_->merge(new_->thumbnail.file_id, old_->thumbnail.file_id));
+    }
+  }
+  LOG_STATUS(td_->file_manager_->merge(new_id, old_id));
+  if (can_delete_old) {
+    audios_.erase(old_id);
+  }
+  return true;
+}
+
+string AudiosManager::get_audio_search_text(FileId file_id) const {
+  auto audio = get_audio(file_id);
+  CHECK(audio != nullptr);
+  return PSTRING() << audio->file_name << " " << audio->title << " " << audio->performer;
+}
+
+FileId AudiosManager::get_audio_thumbnail_file_id(FileId file_id) const {
+  auto audio = get_audio(file_id);
+  CHECK(audio != nullptr);
+  return audio->thumbnail.file_id;
+}
+
+void AudiosManager::delete_audio_thumbnail(FileId file_id) {
+  auto &audio = audios_[file_id];
+  CHECK(audio != nullptr);
+  audio->thumbnail = PhotoSize();
+}
+
+void AudiosManager::create_audio(FileId file_id, PhotoSize thumbnail, string file_name, string mime_type,
+                                 int32 duration, string title, string performer, bool replace) {
+  auto a = std::make_unique<Audio>();
+  a->file_id = file_id;
+  a->file_name = std::move(file_name);
+  a->mime_type = std::move(mime_type);
+  a->duration = max(duration, 0);
+  a->title = std::move(title);
+  a->performer = std::move(performer);
+  a->thumbnail = std::move(thumbnail);
+  on_get_audio(std::move(a), replace);
+}
+
+SecretInputMedia AudiosManager::get_secret_input_media(FileId audio_file_id,
+                                                       tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                                       const string &caption, BufferSlice thumbnail) const {
+  auto *audio = get_audio(audio_file_id);
+  CHECK(audio != nullptr);
+  auto file_view = td_->file_manager_->get_file_view(audio_file_id);
+  auto &encryption_key = file_view.encryption_key();
+  if (encryption_key.empty()) {
+    return SecretInputMedia{};
+  }
+  if (file_view.has_remote_location()) {
+    input_file = file_view.remote_location().as_input_encrypted_file();
+  }
+  if (!input_file) {
+    return SecretInputMedia{};
+  }
+  if (audio->thumbnail.file_id.is_valid() && thumbnail.empty()) {
+    return SecretInputMedia{};
+  }
+  vector<tl_object_ptr<secret_api::DocumentAttribute>> attributes;
+  if (!audio->file_name.empty()) {
+    attributes.push_back(make_tl_object<secret_api::documentAttributeFilename>(audio->file_name));
+  }
+  attributes.push_back(make_tl_object<secret_api::documentAttributeAudio>(
+      secret_api::documentAttributeAudio::Flags::TITLE_MASK | secret_api::documentAttributeAudio::Flags::PERFORMER_MASK,
+      false /*ignored*/, audio->duration, audio->title, audio->performer, BufferSlice()));
+
+  return SecretInputMedia{
+      std::move(input_file),
+      make_tl_object<secret_api::decryptedMessageMediaDocument>(
+          std::move(thumbnail), audio->thumbnail.dimensions.width, audio->thumbnail.dimensions.height, audio->mime_type,
+          narrow_cast<int32>(file_view.size()), BufferSlice(encryption_key.key_slice()),
+          BufferSlice(encryption_key.iv_slice()), std::move(attributes), caption)};
+}
+
+tl_object_ptr<telegram_api::InputMedia> AudiosManager::get_input_media(
+    FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file,
+    tl_object_ptr<telegram_api::InputFile> input_thumbnail) const {
+  auto file_view = td_->file_manager_->get_file_view(file_id);
+  if (file_view.is_encrypted()) {
+    return nullptr;
+  }
+  if (file_view.has_remote_location() && !file_view.remote_location().is_web()) {
+    return make_tl_object<telegram_api::inputMediaDocument>(0, file_view.remote_location().as_input_document(), 0);
+  }
+  if (file_view.has_url()) {
+    return make_tl_object<telegram_api::inputMediaDocumentExternal>(0, file_view.url(), 0);
+  }
+  CHECK(!file_view.has_remote_location());
+
+  if (input_file != nullptr) {
+    const Audio *audio = get_audio(file_id);
+    CHECK(audio != nullptr);
+
+    vector<tl_object_ptr<telegram_api::DocumentAttribute>> attributes;
+    attributes.push_back(make_tl_object<telegram_api::documentAttributeAudio>(
+        telegram_api::documentAttributeAudio::TITLE_MASK | telegram_api::documentAttributeAudio::PERFORMER_MASK,
+        false /*ignored*/, audio->duration, audio->title, audio->performer, BufferSlice()));
+    if (!audio->file_name.empty()) {
+      attributes.push_back(make_tl_object<telegram_api::documentAttributeFilename>(audio->file_name));
+    }
+    string mime_type = audio->mime_type;
+    if (!begins_with(mime_type, "audio/")) {
+      mime_type = "audio/mpeg";
+    }
+    int32 flags = 0;
+    if (input_thumbnail != nullptr) {
+      flags |= telegram_api::inputMediaUploadedDocument::THUMB_MASK;
+    }
+    return make_tl_object<telegram_api::inputMediaUploadedDocument>(
+        flags, false /*ignored*/, std::move(input_file), std::move(input_thumbnail), mime_type, std::move(attributes),
+        vector<tl_object_ptr<telegram_api::InputDocument>>(), 0);
+  }
+
+  return nullptr;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/AudiosManager.h b/libs/tdlib/td/td/telegram/AudiosManager.h
new file mode 100644
index 0000000000..68624cf451
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/AudiosManager.h
@@ -0,0 +1,85 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/files/FileId.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/SecretInputMedia.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+
+#include <unordered_map>
+
+namespace td {
+class Td;
+}  // namespace td
+
+namespace td {
+
+class AudiosManager {
+ public:
+  explicit AudiosManager(Td *td);
+
+  int32 get_audio_duration(FileId file_id);
+
+  tl_object_ptr<td_api::audio> get_audio_object(FileId file_id);
+
+  void create_audio(FileId file_id, PhotoSize thumbnail, string file_name, string mime_type, int32 duration,
+                    string title, string performer, bool replace);
+
+  tl_object_ptr<telegram_api::InputMedia> get_input_media(FileId file_id,
+                                                          tl_object_ptr<telegram_api::InputFile> input_file,
+                                                          tl_object_ptr<telegram_api::InputFile> input_thumbnail) const;
+
+  SecretInputMedia get_secret_input_media(FileId audio_file_id,
+                                          tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                          const string &caption, BufferSlice thumbnail) const;
+
+  FileId get_audio_thumbnail_file_id(FileId file_id) const;
+
+  void delete_audio_thumbnail(FileId file_id);
+
+  FileId dup_audio(FileId new_id, FileId old_id);
+
+  bool merge_audios(FileId new_id, FileId old_id, bool can_delete_old);
+
+  template <class T>
+  void store_audio(FileId file_id, T &storer) const;
+
+  template <class T>
+  FileId parse_audio(T &parser);
+
+  string get_audio_search_text(FileId file_id) const;
+
+ private:
+  class Audio {
+   public:
+    string file_name;
+    string mime_type;
+    int32 duration = 0;
+    string title;
+    string performer;
+    PhotoSize thumbnail;
+
+    FileId file_id;
+
+    bool is_changed = true;
+  };
+
+  const Audio *get_audio(FileId file_id) const;
+
+  FileId on_get_audio(std::unique_ptr<Audio> new_audio, bool replace);
+
+  Td *td_;
+  std::unordered_map<FileId, unique_ptr<Audio>, FileIdHash> audios_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/AudiosManager.hpp b/libs/tdlib/td/td/telegram/AudiosManager.hpp
new file mode 100644
index 0000000000..d9813352ab
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/AudiosManager.hpp
@@ -0,0 +1,45 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/telegram/AudiosManager.h"
+
+#include "td/telegram/files/FileId.hpp"
+#include "td/telegram/Photo.hpp"
+
+#include "td/utils/logging.h"
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+
+template <class T>
+void AudiosManager::store_audio(FileId file_id, T &storer) const {
+  auto it = audios_.find(file_id);
+  CHECK(it != audios_.end());
+  const Audio *audio = it->second.get();
+  store(audio->file_name, storer);
+  store(audio->mime_type, storer);
+  store(audio->duration, storer);
+  store(audio->title, storer);
+  store(audio->performer, storer);
+  store(audio->thumbnail, storer);
+  store(file_id, storer);
+}
+
+template <class T>
+FileId AudiosManager::parse_audio(T &parser) {
+  auto audio = make_unique<Audio>();
+  parse(audio->file_name, parser);
+  parse(audio->mime_type, parser);
+  parse(audio->duration, parser);
+  parse(audio->title, parser);
+  parse(audio->performer, parser);
+  parse(audio->thumbnail, parser);
+  parse(audio->file_id, parser);
+  return on_get_audio(std::move(audio), true);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/AuthManager.cpp b/libs/tdlib/td/td/telegram/AuthManager.cpp
new file mode 100644
index 0000000000..64915de36b
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/AuthManager.cpp
@@ -0,0 +1,897 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/AuthManager.h"
+#include "td/telegram/AuthManager.hpp"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/ConfigManager.h"
+#include "td/telegram/ConfigShared.h"
+#include "td/telegram/ContactsManager.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/misc.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+#include "td/telegram/Td.h"
+#include "td/telegram/UpdatesManager.h"
+
+#include "td/telegram/logevent/LogEvent.h"
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/crypto.h"
+#include "td/utils/logging.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Time.h"
+
+namespace td {
+
+// SendCodeHelper
+void SendCodeHelper::on_sent_code(telegram_api::object_ptr<telegram_api::auth_sentCode> sent_code) {
+  phone_registered_ = (sent_code->flags_ & SENT_CODE_FLAG_IS_USER_REGISTERED) != 0;
+  phone_code_hash_ = sent_code->phone_code_hash_;
+  sent_code_info_ = get_authentication_code_info(std::move(sent_code->type_));
+  next_code_info_ = get_authentication_code_info(std::move(sent_code->next_type_));
+  next_code_timestamp_ = Timestamp::in((sent_code->flags_ & SENT_CODE_FLAG_HAS_TIMEOUT) != 0 ? sent_code->timeout_ : 0);
+}
+
+td_api::object_ptr<td_api::authorizationStateWaitCode> SendCodeHelper::get_authorization_state_wait_code() const {
+  return make_tl_object<td_api::authorizationStateWaitCode>(phone_registered_, get_authentication_code_info_object());
+}
+
+td_api::object_ptr<td_api::authenticationCodeInfo> SendCodeHelper::get_authentication_code_info_object() const {
+  return make_tl_object<td_api::authenticationCodeInfo>(
+      phone_number_, get_authentication_code_type_object(sent_code_info_),
+      get_authentication_code_type_object(next_code_info_),
+      max(static_cast<int32>(next_code_timestamp_.in() + 1 - 1e-9), 0));
+}
+
+Result<telegram_api::auth_resendCode> SendCodeHelper::resend_code() {
+  if (next_code_info_.type == AuthenticationCodeInfo::Type::None) {
+    return Status::Error(8, "Authentication code can't be resend");
+  }
+  sent_code_info_ = next_code_info_;
+  next_code_info_ = {};
+  next_code_timestamp_ = {};
+  return telegram_api::auth_resendCode(phone_number_, phone_code_hash_);
+}
+
+Result<telegram_api::auth_sendCode> SendCodeHelper::send_code(Slice phone_number, bool allow_flash_call,
+                                                              bool is_current_phone_number, int32 api_id,
+                                                              const string &api_hash) {
+  if (!phone_number_.empty()) {
+    return Status::Error(8, "Can't change phone");
+  }
+  phone_number_ = phone_number.str();
+  int32 flags = 0;
+  if (allow_flash_call) {
+    flags |= AUTH_SEND_CODE_FLAG_ALLOW_FLASH_CALL;
+  }
+  return telegram_api::auth_sendCode(flags, false /*ignored*/, phone_number_, is_current_phone_number, api_id,
+                                     api_hash);
+}
+
+Result<telegram_api::account_sendChangePhoneCode> SendCodeHelper::send_change_phone_code(Slice phone_number,
+                                                                                         bool allow_flash_call,
+                                                                                         bool is_current_phone_number) {
+  phone_number_ = phone_number.str();
+  int32 flags = 0;
+  if (allow_flash_call) {
+    flags |= AUTH_SEND_CODE_FLAG_ALLOW_FLASH_CALL;
+  }
+  return telegram_api::account_sendChangePhoneCode(flags, false /*ignored*/, phone_number_, is_current_phone_number);
+}
+
+SendCodeHelper::AuthenticationCodeInfo SendCodeHelper::get_authentication_code_info(
+    tl_object_ptr<telegram_api::auth_CodeType> &&code_type_ptr) {
+  if (code_type_ptr == nullptr) {
+    return AuthenticationCodeInfo();
+  }
+
+  switch (code_type_ptr->get_id()) {
+    case telegram_api::auth_codeTypeSms::ID:
+      return {AuthenticationCodeInfo::Type::Sms, 0, ""};
+    case telegram_api::auth_codeTypeCall::ID:
+      return {AuthenticationCodeInfo::Type::Call, 0, ""};
+    case telegram_api::auth_codeTypeFlashCall::ID:
+      return {AuthenticationCodeInfo::Type::FlashCall, 0, ""};
+    default:
+      UNREACHABLE();
+      return AuthenticationCodeInfo();
+  }
+}
+
+SendCodeHelper::AuthenticationCodeInfo SendCodeHelper::get_authentication_code_info(
+    tl_object_ptr<telegram_api::auth_SentCodeType> &&sent_code_type_ptr) {
+  CHECK(sent_code_type_ptr != nullptr);
+  switch (sent_code_type_ptr->get_id()) {
+    case telegram_api::auth_sentCodeTypeApp::ID: {
+      auto code_type = move_tl_object_as<telegram_api::auth_sentCodeTypeApp>(sent_code_type_ptr);
+      return AuthenticationCodeInfo{AuthenticationCodeInfo::Type::Message, code_type->length_, ""};
+    }
+    case telegram_api::auth_sentCodeTypeSms::ID: {
+      auto code_type = move_tl_object_as<telegram_api::auth_sentCodeTypeSms>(sent_code_type_ptr);
+      return AuthenticationCodeInfo{AuthenticationCodeInfo::Type::Sms, code_type->length_, ""};
+    }
+    case telegram_api::auth_sentCodeTypeCall::ID: {
+      auto code_type = move_tl_object_as<telegram_api::auth_sentCodeTypeCall>(sent_code_type_ptr);
+      return AuthenticationCodeInfo{AuthenticationCodeInfo::Type::Call, code_type->length_, ""};
+    }
+    case telegram_api::auth_sentCodeTypeFlashCall::ID: {
+      auto code_type = move_tl_object_as<telegram_api::auth_sentCodeTypeFlashCall>(sent_code_type_ptr);
+      return AuthenticationCodeInfo{AuthenticationCodeInfo::Type::FlashCall, 0, code_type->pattern_};
+    }
+    default:
+      UNREACHABLE();
+      return AuthenticationCodeInfo();
+  }
+}
+
+tl_object_ptr<td_api::AuthenticationCodeType> SendCodeHelper::get_authentication_code_type_object(
+    const AuthenticationCodeInfo &authentication_code_info) {
+  switch (authentication_code_info.type) {
+    case AuthenticationCodeInfo::Type::None:
+      return nullptr;
+    case AuthenticationCodeInfo::Type::Message:
+      return make_tl_object<td_api::authenticationCodeTypeTelegramMessage>(authentication_code_info.length);
+    case AuthenticationCodeInfo::Type::Sms:
+      return make_tl_object<td_api::authenticationCodeTypeSms>(authentication_code_info.length);
+    case AuthenticationCodeInfo::Type::Call:
+      return make_tl_object<td_api::authenticationCodeTypeCall>(authentication_code_info.length);
+    case AuthenticationCodeInfo::Type::FlashCall:
+      return make_tl_object<td_api::authenticationCodeTypeFlashCall>(authentication_code_info.pattern);
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+// ChangePhoneNumberManager
+void ChangePhoneNumberManager::get_state(uint64 query_id) {
+  tl_object_ptr<td_api::Object> obj;
+  switch (state_) {
+    case State::Ok:
+      obj = make_tl_object<td_api::ok>();
+      break;
+    case State::WaitCode:
+      obj = send_code_helper_.get_authentication_code_info_object();
+      break;
+  }
+  CHECK(obj);
+  send_closure(G()->td(), &Td::send_result, query_id, std::move(obj));
+}
+
+ChangePhoneNumberManager::ChangePhoneNumberManager(ActorShared<> parent) : parent_(std::move(parent)) {
+}
+void ChangePhoneNumberManager::change_phone_number(uint64 query_id, string phone_number, bool allow_flash_call,
+                                                   bool is_current_phone_number) {
+  if (phone_number.empty()) {
+    return on_query_error(query_id, Status::Error(8, "Phone number can't be empty"));
+  }
+  auto r_send_code = send_code_helper_.send_change_phone_code(phone_number, allow_flash_call, is_current_phone_number);
+  if (r_send_code.is_error()) {
+    return on_query_error(query_id, r_send_code.move_as_error());
+  }
+
+  on_new_query(query_id);
+
+  start_net_query(NetQueryType::SendCode, G()->net_query_creator().create(create_storer(r_send_code.move_as_ok())));
+}
+
+void ChangePhoneNumberManager::resend_authentication_code(uint64 query_id) {
+  if (state_ != State::WaitCode) {
+    return on_query_error(query_id, Status::Error(8, "resendAuthenticationCode unexpected"));
+  }
+
+  auto r_resend_code = send_code_helper_.resend_code();
+  if (r_resend_code.is_error()) {
+    return on_query_error(query_id, r_resend_code.move_as_error());
+  }
+
+  on_new_query(query_id);
+
+  start_net_query(NetQueryType::SendCode,
+                  G()->net_query_creator().create(create_storer(r_resend_code.move_as_ok()), DcId::main(),
+                                                  NetQuery::Type::Common, NetQuery::AuthFlag::Off));
+}
+
+void ChangePhoneNumberManager::check_code(uint64 query_id, string code) {
+  if (state_ != State::WaitCode) {
+    return on_query_error(query_id, Status::Error(8, "checkAuthenticationCode unexpected"));
+  }
+
+  on_new_query(query_id);
+  start_net_query(NetQueryType::ChangePhone,
+                  G()->net_query_creator().create(create_storer(telegram_api::account_changePhone(
+                      send_code_helper_.phone_number().str(), send_code_helper_.phone_code_hash().str(), code))));
+}
+
+void ChangePhoneNumberManager::on_new_query(uint64 query_id) {
+  if (query_id_ != 0) {
+    on_query_error(Status::Error(9, "Another authorization query has started"));
+  }
+  net_query_id_ = 0;
+  net_query_type_ = NetQueryType::None;
+  query_id_ = query_id;
+  // TODO: cancel older net_query
+}
+
+void ChangePhoneNumberManager::on_query_error(Status status) {
+  CHECK(query_id_ != 0);
+  auto id = query_id_;
+  query_id_ = 0;
+  net_query_id_ = 0;
+  net_query_type_ = NetQueryType::None;
+  on_query_error(id, std::move(status));
+}
+
+void ChangePhoneNumberManager::on_query_error(uint64 id, Status status) {
+  send_closure(G()->td(), &Td::send_error, id, std::move(status));
+}
+
+void ChangePhoneNumberManager::on_query_ok() {
+  CHECK(query_id_ != 0);
+  auto id = query_id_;
+  net_query_id_ = 0;
+  net_query_type_ = NetQueryType::None;
+  query_id_ = 0;
+  get_state(id);
+}
+
+void ChangePhoneNumberManager::start_net_query(NetQueryType net_query_type, NetQueryPtr net_query) {
+  // TODO: cancel old net_query?
+  net_query_type_ = net_query_type;
+  net_query_id_ = net_query->id();
+  G()->net_query_dispatcher().dispatch_with_callback(std::move(net_query), actor_shared(this));
+}
+
+void ChangePhoneNumberManager::on_change_phone_result(NetQueryPtr &result) {
+  auto r_change_phone = fetch_result<telegram_api::account_changePhone>(result->ok());
+  if (r_change_phone.is_error()) {
+    return on_query_error(r_change_phone.move_as_error());
+  }
+  state_ = State::Ok;
+  on_query_ok();
+}
+
+void ChangePhoneNumberManager::on_send_code_result(NetQueryPtr &result) {
+  auto r_sent_code = fetch_result<telegram_api::account_sendChangePhoneCode>(result->ok());
+  if (r_sent_code.is_error()) {
+    return on_query_error(r_sent_code.move_as_error());
+  }
+  auto sent_code = r_sent_code.move_as_ok();
+
+  LOG(INFO) << "Receive " << to_string(sent_code);
+
+  send_code_helper_.on_sent_code(std::move(sent_code));
+
+  state_ = State::WaitCode;
+  on_query_ok();
+}
+
+void ChangePhoneNumberManager::on_result(NetQueryPtr result) {
+  SCOPE_EXIT {
+    result->clear();
+  };
+  NetQueryType type = NetQueryType::None;
+  if (result->id() == net_query_id_) {
+    net_query_id_ = 0;
+    type = net_query_type_;
+    net_query_type_ = NetQueryType::None;
+    if (result->is_error()) {
+      if (query_id_ != 0) {
+        on_query_error(std::move(result->error()));
+      }
+      return;
+    }
+  }
+  switch (type) {
+    case NetQueryType::None:
+      result->ignore();
+      break;
+    case NetQueryType::SendCode:
+      on_send_code_result(result);
+      break;
+    case NetQueryType::ChangePhone:
+      on_change_phone_result(result);
+      break;
+  }
+}
+
+void ChangePhoneNumberManager::tear_down() {
+  parent_.reset();
+}
+
+// AuthManager
+AuthManager::AuthManager(int32 api_id, const string &api_hash, ActorShared<> parent)
+    : parent_(std::move(parent)), api_id_(api_id), api_hash_(api_hash) {
+  string auth_str = G()->td_db()->get_binlog_pmc()->get("auth");
+  if (auth_str == "ok") {
+    string is_bot_str = G()->td_db()->get_binlog_pmc()->get("auth_is_bot");
+    if (is_bot_str == "true") {
+      is_bot_ = true;
+    }
+    auto my_id = ContactsManager::load_my_id();
+    if (my_id.is_valid()) {
+      // just in case
+      G()->shared_config().set_option_integer("my_id", my_id.get());
+      update_state(State::Ok);
+    } else {
+      LOG(ERROR) << "Restore unknown my_id";
+      ContactsManager::send_get_me_query(
+          G()->td().get_actor_unsafe(),
+          PromiseCreator::lambda([this](Result<Unit> result) { update_state(State::Ok); }));
+    }
+  } else if (auth_str == "logout") {
+    update_state(State::LoggingOut);
+  } else {
+    if (!load_state()) {
+      update_state(State::WaitPhoneNumber);
+    }
+  }
+}
+
+void AuthManager::start_up() {
+  if (state_ == State::LoggingOut) {
+    start_net_query(NetQueryType::LogOut, G()->net_query_creator().create(create_storer(telegram_api::auth_logOut())));
+  }
+}
+void AuthManager::tear_down() {
+  parent_.reset();
+}
+
+bool AuthManager::is_bot() const {
+  return is_authorized() && is_bot_;
+}
+
+void AuthManager::set_is_bot(bool is_bot) {
+  if (!is_bot_ && is_bot && api_id_ == 23818) {
+    LOG(ERROR) << "Fix is_bot to " << is_bot;
+    G()->td_db()->get_binlog_pmc()->set("auth_is_bot", "true");
+    is_bot_ = true;
+  }
+}
+
+bool AuthManager::is_authorized() const {
+  return state_ == State::Ok;
+}
+
+tl_object_ptr<td_api::AuthorizationState> AuthManager::get_authorization_state_object(State authorization_state) const {
+  switch (authorization_state) {
+    case State::Ok:
+      return make_tl_object<td_api::authorizationStateReady>();
+    case State::WaitCode:
+      return send_code_helper_.get_authorization_state_wait_code();
+    case State::WaitPhoneNumber:
+      return make_tl_object<td_api::authorizationStateWaitPhoneNumber>();
+    case State::WaitPassword:
+      return make_tl_object<td_api::authorizationStateWaitPassword>(
+          wait_password_state_.hint_, wait_password_state_.has_recovery_, wait_password_state_.email_address_pattern_);
+    case State::LoggingOut:
+      return make_tl_object<td_api::authorizationStateLoggingOut>();
+    case State::Closing:
+      return make_tl_object<td_api::authorizationStateClosing>();
+    case State::None:
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+void AuthManager::get_state(uint64 query_id) {
+  if (state_ == State::None) {
+    pending_get_authorization_state_requests_.push_back(query_id);
+  } else {
+    send_closure(G()->td(), &Td::send_result, query_id, get_authorization_state_object(state_));
+  }
+}
+
+void AuthManager::check_bot_token(uint64 query_id, string bot_token) {
+  if (state_ != State::WaitPhoneNumber && state_ != State::Ok) {
+    // TODO do not allow State::Ok
+    return on_query_error(query_id, Status::Error(8, "checkAuthenticationBotToken unexpected"));
+  }
+  if (!send_code_helper_.phone_number().empty()) {
+    return on_query_error(
+        query_id, Status::Error(8, "Cannot set bot token after authentication beginning. You need to log out first"));
+  }
+  if (was_check_bot_token_ && bot_token_ != bot_token) {
+    return on_query_error(query_id, Status::Error(8, "Cannot change bot token. You need to log out first"));
+  }
+  if (state_ == State::Ok) {
+    if (!is_bot_) {
+      // fix old bots
+      const int32 AUTH_IS_BOT_FIXED_DATE = 1500940800;
+      if (G()->shared_config().get_option_integer("authorization_date") < AUTH_IS_BOT_FIXED_DATE) {
+        G()->td_db()->get_binlog_pmc()->set("auth_is_bot", "true");
+        is_bot_ = true;
+      }
+    }
+    return send_ok(query_id);
+  }
+
+  on_new_query(query_id);
+  bot_token_ = bot_token;
+  was_check_bot_token_ = true;
+  start_net_query(NetQueryType::BotAuthentication,
+                  G()->net_query_creator().create(
+                      create_storer(telegram_api::auth_importBotAuthorization(0, api_id_, api_hash_, bot_token_)),
+                      DcId::main(), NetQuery::Type::Common, NetQuery::AuthFlag::Off));
+}
+
+void AuthManager::set_phone_number(uint64 query_id, string phone_number, bool allow_flash_call,
+                                   bool is_current_phone_number) {
+  if (state_ != State::WaitPhoneNumber) {
+    if ((state_ == State::WaitCode || state_ == State::WaitPassword) && net_query_id_ == 0) {
+      // ok
+    } else {
+      return on_query_error(query_id, Status::Error(8, "setAuthenticationPhoneNumber unexpected"));
+    }
+  }
+  if (was_check_bot_token_) {
+    return on_query_error(
+        query_id, Status::Error(8, "Cannot set phone number after bot token was entered. You need to log out first"));
+  }
+  if (phone_number.empty()) {
+    return on_query_error(query_id, Status::Error(8, "Phone number can't be empty"));
+  }
+
+  auto r_send_code =
+      send_code_helper_.send_code(phone_number, allow_flash_call, is_current_phone_number, api_id_, api_hash_);
+  if (r_send_code.is_error()) {
+    send_code_helper_ = SendCodeHelper();
+    r_send_code =
+        send_code_helper_.send_code(phone_number, allow_flash_call, is_current_phone_number, api_id_, api_hash_);
+    if (r_send_code.is_error()) {
+      return on_query_error(query_id, r_send_code.move_as_error());
+    }
+  }
+
+  on_new_query(query_id);
+
+  start_net_query(NetQueryType::SendCode,
+                  G()->net_query_creator().create(create_storer(r_send_code.move_as_ok()), DcId::main(),
+                                                  NetQuery::Type::Common, NetQuery::AuthFlag::Off));
+}
+
+void AuthManager::resend_authentication_code(uint64 query_id) {
+  if (state_ != State::WaitCode || was_check_bot_token_) {
+    return on_query_error(query_id, Status::Error(8, "resendAuthenticationCode unexpected"));
+  }
+
+  auto r_resend_code = send_code_helper_.resend_code();
+  if (r_resend_code.is_error()) {
+    return on_query_error(query_id, r_resend_code.move_as_error());
+  }
+
+  on_new_query(query_id);
+
+  start_net_query(NetQueryType::SendCode,
+                  G()->net_query_creator().create(create_storer(r_resend_code.move_as_ok()), DcId::main(),
+                                                  NetQuery::Type::Common, NetQuery::AuthFlag::Off));
+}
+
+void AuthManager::check_code(uint64 query_id, string code, string first_name, string last_name) {
+  if (state_ != State::WaitCode) {
+    return on_query_error(query_id, Status::Error(8, "checkAuthenticationCode unexpected"));
+  }
+  first_name = clean_name(first_name, MAX_NAME_LENGTH);
+  if (!send_code_helper_.phone_registered() && first_name.empty()) {
+    return on_query_error(query_id, Status::Error(8, "First name can't be empty"));
+  }
+
+  on_new_query(query_id);
+  if (send_code_helper_.phone_registered()) {
+    start_net_query(NetQueryType::SignIn,
+                    G()->net_query_creator().create(
+                        create_storer(telegram_api::auth_signIn(send_code_helper_.phone_number().str(),
+                                                                send_code_helper_.phone_code_hash().str(), code)),
+                        DcId::main(), NetQuery::Type::Common, NetQuery::AuthFlag::Off));
+  } else {
+    last_name = clean_name(last_name, MAX_NAME_LENGTH);
+    start_net_query(
+        NetQueryType::SignUp,
+        G()->net_query_creator().create(create_storer(telegram_api::auth_signUp(
+                                            send_code_helper_.phone_number().str(),
+                                            send_code_helper_.phone_code_hash().str(), code, first_name, last_name)),
+                                        DcId::main(), NetQuery::Type::Common, NetQuery::AuthFlag::Off));
+  }
+}
+
+void AuthManager::check_password(uint64 query_id, string password) {
+  if (state_ != State::WaitPassword) {
+    return on_query_error(query_id, Status::Error(8, "checkAuthenticationPassword unexpected"));
+  }
+  BufferSlice buf(32);
+  password = wait_password_state_.current_salt_ + password + wait_password_state_.current_salt_;
+  sha256(password, buf.as_slice());
+
+  on_new_query(query_id);
+  start_net_query(NetQueryType::CheckPassword,
+                  G()->net_query_creator().create(create_storer(telegram_api::auth_checkPassword(std::move(buf))),
+                                                  DcId::main(), NetQuery::Type::Common, NetQuery::AuthFlag::Off));
+}
+
+void AuthManager::request_password_recovery(uint64 query_id) {
+  if (state_ != State::WaitPassword) {
+    return on_query_error(query_id, Status::Error(8, "requestAuthenticationPasswordRecovery unexpected"));
+  }
+
+  on_new_query(query_id);
+  start_net_query(NetQueryType::RequestPasswordRecovery,
+                  G()->net_query_creator().create(create_storer(telegram_api::auth_requestPasswordRecovery()),
+                                                  DcId::main(), NetQuery::Type::Common, NetQuery::AuthFlag::Off));
+}
+
+void AuthManager::recover_password(uint64 query_id, string code) {
+  if (state_ != State::WaitPassword) {
+    return on_query_error(query_id, Status::Error(8, "recoverAuthenticationPassword unexpected"));
+  }
+
+  on_new_query(query_id);
+  start_net_query(NetQueryType::RecoverPassword,
+                  G()->net_query_creator().create(create_storer(telegram_api::auth_recoverPassword(code)), DcId::main(),
+                                                  NetQuery::Type::Common, NetQuery::AuthFlag::Off));
+}
+
+void AuthManager::logout(uint64 query_id) {
+  if (state_ == State::Closing) {
+    return on_query_error(query_id, Status::Error(8, "Already logged out"));
+  }
+  if (state_ == State::LoggingOut) {
+    return on_query_error(query_id, Status::Error(8, "Already logging out"));
+  }
+  on_new_query(query_id);
+  if (state_ != State::Ok) {
+    update_state(State::LoggingOut);
+    // TODO: could skip full logout if still no authorization
+    // TODO: send auth.cancelCode if state_ == State::WaitCode
+    send_closure_later(G()->td(), &Td::destroy);
+    on_query_ok();
+  } else {
+    LOG(INFO) << "Logging out";
+    G()->td_db()->get_binlog_pmc()->set("auth", "logout");
+    update_state(State::LoggingOut);
+    start_net_query(NetQueryType::LogOut, G()->net_query_creator().create(create_storer(telegram_api::auth_logOut())));
+  }
+}
+
+void AuthManager::delete_account(uint64 query_id, const string &reason) {
+  if (state_ != State::Ok) {
+    return on_query_error(query_id, Status::Error(8, "Need to log in first"));
+  }
+  on_new_query(query_id);
+  LOG(INFO) << "Deleting account";
+  update_state(State::LoggingOut);
+  start_net_query(NetQueryType::DeleteAccount,
+                  G()->net_query_creator().create(create_storer(telegram_api::account_deleteAccount(reason))));
+}
+
+void AuthManager::on_closing() {
+  update_state(State::Closing);
+}
+
+void AuthManager::on_new_query(uint64 query_id) {
+  if (query_id_ != 0) {
+    on_query_error(Status::Error(9, "Another authorization query has started"));
+  }
+  net_query_id_ = 0;
+  net_query_type_ = NetQueryType::None;
+  query_id_ = query_id;
+  // TODO: cancel older net_query
+}
+
+void AuthManager::on_query_error(Status status) {
+  CHECK(query_id_ != 0);
+  auto id = query_id_;
+  query_id_ = 0;
+  net_query_id_ = 0;
+  net_query_type_ = NetQueryType::None;
+  on_query_error(id, std::move(status));
+}
+
+void AuthManager::on_query_error(uint64 id, Status status) {
+  send_closure(G()->td(), &Td::send_error, id, std::move(status));
+}
+
+void AuthManager::on_query_ok() {
+  CHECK(query_id_ != 0);
+  auto id = query_id_;
+  net_query_id_ = 0;
+  net_query_type_ = NetQueryType::None;
+  query_id_ = 0;
+  send_ok(id);
+}
+
+void AuthManager::send_ok(uint64 query_id) {
+  send_closure(G()->td(), &Td::send_result, query_id, td_api::make_object<td_api::ok>());
+}
+
+void AuthManager::start_net_query(NetQueryType net_query_type, NetQueryPtr net_query) {
+  // TODO: cancel old net_query?
+  net_query_type_ = net_query_type;
+  net_query_id_ = net_query->id();
+  G()->net_query_dispatcher().dispatch_with_callback(std::move(net_query), actor_shared(this));
+}
+
+void AuthManager::on_send_code_result(NetQueryPtr &result) {
+  auto r_sent_code = fetch_result<telegram_api::auth_sendCode>(result->ok());
+  if (r_sent_code.is_error()) {
+    return on_query_error(r_sent_code.move_as_error());
+  }
+  auto sent_code = r_sent_code.move_as_ok();
+
+  LOG(INFO) << "Receive " << to_string(sent_code);
+
+  send_code_helper_.on_sent_code(std::move(sent_code));
+
+  update_state(State::WaitCode, true);
+  on_query_ok();
+}
+
+void AuthManager::on_get_password_result(NetQueryPtr &result) {
+  auto r_password = fetch_result<telegram_api::account_getPassword>(result->ok());
+  if (r_password.is_error()) {
+    return on_query_error(r_password.move_as_error());
+  }
+  auto password = r_password.move_as_ok();
+  wait_password_state_ = WaitPasswordState();
+  if (password->get_id() == telegram_api::account_noPassword::ID) {
+    auto no_password = move_tl_object_as<telegram_api::account_noPassword>(password);
+    wait_password_state_.new_salt_ = no_password->new_salt_.as_slice().str();
+  } else {
+    CHECK(password->get_id() == telegram_api::account_password::ID);
+    auto password_info = move_tl_object_as<telegram_api::account_password>(password);
+    wait_password_state_.current_salt_ = password_info->current_salt_.as_slice().str();
+    wait_password_state_.new_salt_ = password_info->new_salt_.as_slice().str();
+    wait_password_state_.hint_ = password_info->hint_;
+    wait_password_state_.has_recovery_ = password_info->has_recovery_;
+  }
+  update_state(State::WaitPassword);
+  on_query_ok();
+}
+
+void AuthManager::on_request_password_recovery_result(NetQueryPtr &result) {
+  auto r_email_address_pattern = fetch_result<telegram_api::auth_requestPasswordRecovery>(result->ok());
+  if (r_email_address_pattern.is_error()) {
+    return on_query_error(r_email_address_pattern.move_as_error());
+  }
+  auto email_address_pattern = r_email_address_pattern.move_as_ok();
+  CHECK(email_address_pattern->get_id() == telegram_api::auth_passwordRecovery::ID);
+  wait_password_state_.email_address_pattern_ = email_address_pattern->email_pattern_;
+  update_state(State::WaitPassword, true);
+  on_query_ok();
+}
+
+void AuthManager::on_authentication_result(NetQueryPtr &result, bool expected_flag) {
+  auto r_sign_in = fetch_result<telegram_api::auth_signIn>(result->ok());
+  if (r_sign_in.is_error()) {
+    if (expected_flag && query_id_ != 0) {
+      return on_query_error(r_sign_in.move_as_error());
+    }
+    return;
+  }
+  auto sign_in = r_sign_in.move_as_ok();
+  CHECK(sign_in->get_id() == telegram_api::auth_authorization::ID);
+  on_authorization(std::move(sign_in));
+}
+
+void AuthManager::on_log_out_result(NetQueryPtr &result) {
+  Status status;
+  if (result->is_ok()) {
+    auto r_log_out = fetch_result<telegram_api::auth_logOut>(result->ok());
+    if (r_log_out.is_ok()) {
+      if (!r_log_out.ok()) {
+        status = Status::Error(500, "auth.logOut returned false!");
+      }
+    } else {
+      status = r_log_out.move_as_error();
+    }
+  } else {
+    status = std::move(result->error());
+  }
+  LOG_IF(ERROR, status.is_error()) << "auth.logOut failed: " << status;
+  // state_ will stay logout, so no queries will work.
+  send_closure_later(G()->td(), &Td::destroy);
+  if (query_id_ != 0) {
+    on_query_ok();
+  }
+}
+
+void AuthManager::on_delete_account_result(NetQueryPtr &result) {
+  Status status;
+  if (result->is_ok()) {
+    auto r_delete_account = fetch_result<telegram_api::account_deleteAccount>(result->ok());
+    if (r_delete_account.is_ok()) {
+      if (!r_delete_account.ok()) {
+        status = Status::Error(500, "Receive false as result of the request");
+      }
+    } else {
+      status = r_delete_account.move_as_error();
+    }
+  } else {
+    status = std::move(result->error());
+  }
+  if (status.is_error() && status.error().message() != "USER_DEACTIVATED") {
+    update_state(State::Ok);
+    LOG(WARNING) << "account.deleteAccount failed: " << status;
+    // TODO handle some errors
+    if (query_id_ != 0) {
+      on_query_error(std::move(status));
+    }
+  } else {
+    send_closure_later(G()->td(), &Td::destroy);
+    if (query_id_ != 0) {
+      on_query_ok();
+    }
+  }
+}
+
+void AuthManager::on_authorization(tl_object_ptr<telegram_api::auth_authorization> auth) {
+  G()->shared_config().set_option_integer("authorization_date", G()->unix_time());
+  if (was_check_bot_token_) {
+    is_bot_ = true;
+    G()->td_db()->get_binlog_pmc()->set("auth_is_bot", "true");
+  }
+  G()->td_db()->get_binlog_pmc()->set("auth", "ok");
+  state_ = State::Ok;
+  td->contacts_manager_->on_get_user(std::move(auth->user_), true);
+  update_state(State::Ok, true);
+  if (!td->contacts_manager_->get_my_id("on_authorization").is_valid()) {
+    LOG(ERROR) << "Server doesn't send proper authorization";
+    if (query_id_ != 0) {
+      on_query_error(Status::Error(500, "Server doesn't send proper authorization"));
+    }
+    logout(0);
+    return;
+  }
+  if ((auth->flags_ & telegram_api::auth_authorization::TMP_SESSIONS_MASK) != 0) {
+    G()->shared_config().set_option_integer("session_count", auth->tmp_sessions_);
+  }
+  td->updates_manager_->get_difference("on_authorization");
+  td->on_online_updated(true, true);
+  send_closure(G()->config_manager(), &ConfigManager::request_config);
+  if (query_id_ != 0) {
+    on_query_ok();
+  }
+}
+
+void AuthManager::on_result(NetQueryPtr result) {
+  SCOPE_EXIT {
+    result->clear();
+  };
+  NetQueryType type = NetQueryType::None;
+  if (result->id() == net_query_id_) {
+    net_query_id_ = 0;
+    type = net_query_type_;
+    net_query_type_ = NetQueryType::None;
+    if (result->is_error()) {
+      if (type == NetQueryType::SignIn && result->error().code() == 401 &&
+          result->error().message() == CSlice("SESSION_PASSWORD_NEEDED")) {
+        start_net_query(NetQueryType::GetPassword,
+                        G()->net_query_creator().create(create_storer(telegram_api::account_getPassword()),
+                                                        DcId::main(), NetQuery::Type::Common, NetQuery::AuthFlag::Off));
+        return;
+      }
+      if (type != NetQueryType::LogOut) {
+        if (query_id_ != 0) {
+          if (state_ == State::WaitPhoneNumber) {
+            send_code_helper_ = SendCodeHelper();
+          }
+          on_query_error(std::move(result->error()));
+        }
+        return;
+      }
+    }
+  } else if (result->is_ok() && result->ok_tl_constructor() == telegram_api::auth_authorization::ID) {
+    type = NetQueryType::Authentication;
+  }
+  switch (type) {
+    case NetQueryType::None:
+      result->ignore();
+      break;
+    case NetQueryType::SignIn:
+    case NetQueryType::SignUp:
+    case NetQueryType::BotAuthentication:
+    case NetQueryType::CheckPassword:
+    case NetQueryType::RecoverPassword:
+      on_authentication_result(result, true);
+      break;
+    case NetQueryType::Authentication:
+      on_authentication_result(result, false);
+      break;
+    case NetQueryType::SendCode:
+      on_send_code_result(result);
+      break;
+    case NetQueryType::GetPassword:
+      on_get_password_result(result);
+      break;
+    case NetQueryType::RequestPasswordRecovery:
+      on_request_password_recovery_result(result);
+      break;
+    case NetQueryType::LogOut:
+      on_log_out_result(result);
+      break;
+    case NetQueryType::DeleteAccount:
+      on_delete_account_result(result);
+      break;
+  }
+}
+
+void AuthManager::update_state(State new_state, bool force, bool should_save_state) {
+  if (state_ == new_state && !force) {
+    return;
+  }
+  state_ = new_state;
+  if (should_save_state) {
+    save_state();
+  }
+  send_closure(G()->td(), &Td::send_update,
+               make_tl_object<td_api::updateAuthorizationState>(get_authorization_state_object(state_)));
+
+  if (!pending_get_authorization_state_requests_.empty()) {
+    auto query_ids = std::move(pending_get_authorization_state_requests_);
+    for (auto query_id : query_ids) {
+      send_closure(G()->td(), &Td::send_result, query_id, get_authorization_state_object(state_));
+    }
+  }
+}
+
+bool AuthManager::load_state() {
+  auto data = G()->td_db()->get_binlog_pmc()->get("auth_state");
+  DbState db_state;
+  auto status = log_event_parse(db_state, data);
+  if (status.is_error()) {
+    LOG(INFO) << "Ignore auth_state: " << status;
+    return false;
+  }
+  if (db_state.api_id_ != api_id_ || db_state.api_hash_ != api_hash_) {
+    LOG(INFO) << "Ignore auth_state: api_id or api_hash changed";
+    return false;
+  }
+  if (!db_state.state_timestamp_.is_in_past()) {
+    LOG(INFO) << "Ignore auth_state: timestamp in future";
+    return false;
+  }
+  if (Timestamp::at(db_state.state_timestamp_.at() + 5 * 60).is_in_past()) {
+    LOG(INFO) << "Ignore auth_state: expired " << db_state.state_timestamp_.in();
+    return false;
+  }
+
+  LOG(INFO) << "Load auth_state from db: " << tag("state", static_cast<int32>(db_state.state_));
+  if (db_state.state_ == State::WaitCode) {
+    send_code_helper_ = std::move(db_state.send_code_helper_);
+  } else if (db_state.state_ == State::WaitPassword) {
+    wait_password_state_ = std::move(db_state.wait_password_state_);
+  } else {
+    UNREACHABLE();
+  }
+  update_state(db_state.state_, false, false);
+  return true;
+}
+
+void AuthManager::save_state() {
+  if (state_ != State::WaitCode && state_ != State::WaitPassword) {
+    if (state_ != State::Closing) {
+      G()->td_db()->get_binlog_pmc()->erase("auth_state");
+    }
+    return;
+  }
+
+  DbState db_state;
+  if (state_ == State::WaitCode) {
+    db_state = DbState::wait_code(api_id_, api_hash_, send_code_helper_);
+  } else if (state_ == State::WaitPassword) {
+    db_state = DbState::wait_password(api_id_, api_hash_, wait_password_state_);
+  } else {
+    UNREACHABLE();
+  }
+  G()->td_db()->get_binlog_pmc()->set("auth_state", log_event_store(db_state).as_slice().str());
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/AuthManager.h b/libs/tdlib/td/td/telegram/AuthManager.h
new file mode 100644
index 0000000000..d5e9cbf3d9
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/AuthManager.h
@@ -0,0 +1,268 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/net/NetActor.h"
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+namespace td {
+class SendCodeHelper {
+ public:
+  void on_sent_code(telegram_api::object_ptr<telegram_api::auth_sentCode> sent_code);
+  td_api::object_ptr<td_api::authorizationStateWaitCode> get_authorization_state_wait_code() const;
+  td_api::object_ptr<td_api::authenticationCodeInfo> get_authentication_code_info_object() const;
+  Result<telegram_api::auth_resendCode> resend_code();
+  Result<telegram_api::auth_sendCode> send_code(Slice phone_number, bool allow_flash_call, bool is_current_phone_number,
+                                                int32 api_id, const string &api_hash);
+  Result<telegram_api::account_sendChangePhoneCode> send_change_phone_code(Slice phone_number, bool allow_flash_call,
+                                                                           bool is_current_phone_number);
+
+  Slice phone_number() const {
+    return phone_number_;
+  }
+  Slice phone_code_hash() const {
+    return phone_code_hash_;
+  }
+  bool phone_registered() const {
+    return phone_registered_;
+  }
+
+  template <class T>
+  void store(T &storer) const;
+  template <class T>
+  void parse(T &parser);
+
+ private:
+  static constexpr int32 AUTH_SEND_CODE_FLAG_ALLOW_FLASH_CALL = 1 << 0;
+
+  static constexpr int32 SENT_CODE_FLAG_IS_USER_REGISTERED = 1 << 0;
+  static constexpr int32 SENT_CODE_FLAG_HAS_NEXT_TYPE = 1 << 1;
+  static constexpr int32 SENT_CODE_FLAG_HAS_TIMEOUT = 1 << 2;
+
+  struct AuthenticationCodeInfo {
+    enum class Type : int32 { None, Message, Sms, Call, FlashCall };
+    Type type = Type::None;
+    int32 length = 0;
+    string pattern;
+
+    AuthenticationCodeInfo() = default;
+    AuthenticationCodeInfo(Type type, int length, string pattern)
+        : type(type), length(length), pattern(std::move(pattern)) {
+    }
+
+    template <class T>
+    void store(T &storer) const;
+    template <class T>
+    void parse(T &parser);
+  };
+
+  string phone_number_;
+  bool phone_registered_;
+  string phone_code_hash_;
+
+  SendCodeHelper::AuthenticationCodeInfo sent_code_info_;
+  SendCodeHelper::AuthenticationCodeInfo next_code_info_;
+  Timestamp next_code_timestamp_;
+
+  static AuthenticationCodeInfo get_authentication_code_info(
+      tl_object_ptr<telegram_api::auth_CodeType> &&code_type_ptr);
+  static AuthenticationCodeInfo get_authentication_code_info(
+      tl_object_ptr<telegram_api::auth_SentCodeType> &&sent_code_type_ptr);
+
+  static tl_object_ptr<td_api::AuthenticationCodeType> get_authentication_code_type_object(
+      const AuthenticationCodeInfo &authentication_code_info);
+};
+
+class ChangePhoneNumberManager : public NetActor {
+ public:
+  explicit ChangePhoneNumberManager(ActorShared<> parent);
+  void get_state(uint64 query_id);
+
+  void change_phone_number(uint64 query_id, string phone_number, bool allow_flash_call, bool is_current_phone_number);
+  void resend_authentication_code(uint64 query_id);
+  void check_code(uint64 query_id, string code);
+
+ private:
+  enum class State { Ok, WaitCode } state_ = State::Ok;
+  enum class NetQueryType { None, SendCode, ChangePhone };
+
+  ActorShared<> parent_;
+  uint64 query_id_ = 0;
+  uint64 net_query_id_ = 0;
+  NetQueryType net_query_type_;
+
+  SendCodeHelper send_code_helper_;
+
+  void on_new_query(uint64 query_id);
+  void on_query_error(Status status);
+  void on_query_error(uint64 id, Status status);
+  void on_query_ok();
+  void start_net_query(NetQueryType net_query_type, NetQueryPtr net_query);
+
+  void on_change_phone_result(NetQueryPtr &result);
+  void on_send_code_result(NetQueryPtr &result);
+  void on_result(NetQueryPtr result) override;
+  void tear_down() override;
+};
+
+class AuthManager : public NetActor {
+ public:
+  AuthManager(int32 api_id, const string &api_hash, ActorShared<> parent);
+
+  bool is_bot() const;
+  void set_is_bot(bool is_bot);
+
+  bool is_authorized() const;
+  void get_state(uint64 query_id);
+
+  void set_phone_number(uint64 query_id, string phone_number, bool allow_flash_call, bool is_current_phone_number);
+  void resend_authentication_code(uint64 query_id);
+  void check_code(uint64 query_id, string code, string first_name, string last_name);
+  void check_bot_token(uint64 query_id, string bot_token);
+  void check_password(uint64 query_id, string password);
+  void request_password_recovery(uint64 query_id);
+  void recover_password(uint64 query_id, string code);
+  void logout(uint64 query_id);
+  void delete_account(uint64 query_id, const string &reason);
+
+  void on_closing();
+
+ private:
+  static constexpr size_t MAX_NAME_LENGTH = 255;  // server side limit
+
+  enum class State : int32 {
+    None,
+    WaitPhoneNumber,
+    WaitCode,
+    WaitPassword,
+    Ok,
+    LoggingOut,
+    Closing
+  } state_ = State::None;
+  enum class NetQueryType {
+    None,
+    SignIn,
+    SignUp,
+    SendCode,
+    GetPassword,
+    CheckPassword,
+    RequestPasswordRecovery,
+    RecoverPassword,
+    BotAuthentication,
+    Authentication,
+    LogOut,
+    DeleteAccount
+  };
+
+  struct WaitPasswordState {
+    string current_salt_;
+    string new_salt_;
+    string hint_;
+    bool has_recovery_;
+    string email_address_pattern_;
+
+    template <class T>
+    void store(T &storer) const;
+    template <class T>
+    void parse(T &parser);
+  };
+
+  struct DbState {
+    State state_;
+    int32 api_id_;
+    string api_hash_;
+    Timestamp state_timestamp_;
+
+    // WaitCode
+    SendCodeHelper send_code_helper_;
+
+    //WaitPassword
+    WaitPasswordState wait_password_state_;
+
+    static DbState wait_code(int32 api_id, string api_hash, SendCodeHelper send_code_helper) {
+      DbState state;
+      state.state_ = State::WaitCode;
+      state.api_id_ = api_id;
+      state.api_hash_ = api_hash;
+      state.send_code_helper_ = std::move(send_code_helper);
+      state.state_timestamp_ = Timestamp::now();
+      return state;
+    }
+
+    static DbState wait_password(int32 api_id, string api_hash, WaitPasswordState wait_password_state) {
+      DbState state;
+      state.state_ = State::WaitPassword;
+      state.api_id_ = api_id;
+      state.api_hash_ = api_hash;
+      state.wait_password_state_ = std::move(wait_password_state);
+      state.state_timestamp_ = Timestamp::now();
+      return state;
+    }
+
+    template <class T>
+    void store(T &storer) const;
+    template <class T>
+    void parse(T &parser);
+  };
+
+  bool load_state();
+  void save_state();
+
+  ActorShared<> parent_;
+
+  // STATE
+  // from contructor
+  int32 api_id_;
+  string api_hash_;
+
+  // State::WaitCode
+  SendCodeHelper send_code_helper_;
+
+  // for bots
+  string bot_token_;
+  uint64 query_id_ = 0;
+
+  WaitPasswordState wait_password_state_;
+
+  bool was_check_bot_token_ = false;
+  bool is_bot_ = false;
+  uint64 net_query_id_ = 0;
+  NetQueryType net_query_type_;
+
+  vector<uint64> pending_get_authorization_state_requests_;
+
+  void on_new_query(uint64 query_id);
+  void on_query_error(Status status);
+  void on_query_error(uint64 id, Status status);
+  void on_query_ok();
+  void start_net_query(NetQueryType net_query_type, NetQueryPtr net_query);
+
+  void on_send_code_result(NetQueryPtr &result);
+  void on_get_password_result(NetQueryPtr &result);
+  void on_request_password_recovery_result(NetQueryPtr &result);
+  void on_authentication_result(NetQueryPtr &result, bool expected_flag);
+  void on_log_out_result(NetQueryPtr &result);
+  void on_delete_account_result(NetQueryPtr &result);
+  void on_authorization(tl_object_ptr<telegram_api::auth_authorization> auth);
+
+  void on_result(NetQueryPtr result) override;
+
+  void update_state(State new_state, bool force = false, bool should_save_state = true);
+  tl_object_ptr<td_api::AuthorizationState> get_authorization_state_object(State authorization_state) const;
+  void send_ok(uint64 query_id);
+
+  void start_up() override;
+  void tear_down() override;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/AuthManager.hpp b/libs/tdlib/td/td/telegram/AuthManager.hpp
new file mode 100644
index 0000000000..89027abd61
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/AuthManager.hpp
@@ -0,0 +1,100 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/AuthManager.h"
+
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+template <class T>
+void SendCodeHelper::AuthenticationCodeInfo::store(T &storer) const {
+  using td::store;
+  store(type, storer);
+  store(length, storer);
+  store(pattern, storer);
+}
+template <class T>
+void SendCodeHelper::AuthenticationCodeInfo::parse(T &parser) {
+  using td::parse;
+  parse(type, parser);
+  parse(length, parser);
+  parse(pattern, parser);
+}
+
+template <class T>
+void SendCodeHelper::store(T &storer) const {
+  using td::store;
+  store(phone_number_, storer);
+  store(phone_registered_, storer);
+  store(phone_code_hash_, storer);
+  store(sent_code_info_, storer);
+  store(next_code_info_, storer);
+  store(next_code_timestamp_, storer);
+}
+
+template <class T>
+void SendCodeHelper::parse(T &parser) {
+  using td::parse;
+  parse(phone_number_, parser);
+  parse(phone_registered_, parser);
+  parse(phone_code_hash_, parser);
+  parse(sent_code_info_, parser);
+  parse(next_code_info_, parser);
+  parse(next_code_timestamp_, parser);
+}
+template <class T>
+void AuthManager::WaitPasswordState::store(T &storer) const {
+  using td::store;
+  store(current_salt_, storer);
+  store(new_salt_, storer);
+  store(hint_, storer);
+  store(has_recovery_, storer);
+  store(email_address_pattern_, storer);
+}
+
+template <class T>
+void AuthManager::WaitPasswordState::parse(T &parser) {
+  using td::parse;
+  parse(current_salt_, parser);
+  parse(new_salt_, parser);
+  parse(hint_, parser);
+  parse(has_recovery_, parser);
+  parse(email_address_pattern_, parser);
+}
+
+template <class T>
+void AuthManager::DbState::store(T &storer) const {
+  using td::store;
+  store(state_, storer);
+  store(api_id_, storer);
+  store(api_hash_, storer);
+  store(state_timestamp_, storer);
+
+  if (state_ == State::WaitCode) {
+    store(send_code_helper_, storer);
+  } else if (state_ == State::WaitPassword) {
+    store(wait_password_state_, storer);
+  } else {
+    UNREACHABLE();
+  }
+}
+template <class T>
+void AuthManager::DbState::parse(T &parser) {
+  using td::parse;
+  parse(state_, parser);
+  parse(api_id_, parser);
+  parse(api_hash_, parser);
+  parse(state_timestamp_, parser);
+
+  if (state_ == State::WaitCode) {
+    parse(send_code_helper_, parser);
+  } else if (state_ == State::WaitPassword) {
+    parse(wait_password_state_, parser);
+  } else {
+    parser.set_error(PSTRING() << "Unexpected " << tag("state", static_cast<int32>(state_)));
+  }
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/CallActor.cpp b/libs/tdlib/td/td/telegram/CallActor.cpp
new file mode 100644
index 0000000000..2dd70218e0
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/CallActor.cpp
@@ -0,0 +1,656 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/CallActor.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+#include "td/telegram/telegram_api.hpp"
+
+#include "td/mtproto/crypto.h"
+
+#include "td/telegram/ConfigShared.h"
+#include "td/telegram/ContactsManager.h"
+#include "td/telegram/DhCache.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/misc.h"
+#include "td/telegram/net/NetQueryCreator.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+#include "td/telegram/Td.h"
+#include "td/telegram/UpdatesManager.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/crypto.h"
+#include "td/utils/logging.h"
+#include "td/utils/Random.h"
+
+#include <tuple>
+
+namespace td {
+// CallProtocol
+CallProtocol CallProtocol::from_telegram_api(const telegram_api::phoneCallProtocol &protocol) {
+  CallProtocol res;
+  res.udp_p2p = protocol.udp_p2p_;
+  res.udp_reflector = protocol.udp_reflector_;
+  res.min_layer = protocol.min_layer_;
+  res.max_layer = protocol.max_layer_;
+  return res;
+}
+
+tl_object_ptr<telegram_api::phoneCallProtocol> CallProtocol::as_telegram_api() const {
+  int32 flags = 0;
+  if (udp_p2p) {
+    flags |= telegram_api::phoneCallProtocol::Flags::UDP_P2P_MASK;
+  }
+  if (udp_reflector) {
+    flags |= telegram_api::phoneCallProtocol::Flags::UDP_REFLECTOR_MASK;
+  }
+  return make_tl_object<telegram_api::phoneCallProtocol>(flags, udp_p2p, udp_reflector, min_layer, max_layer);
+}
+
+CallProtocol CallProtocol::from_td_api(const td_api::callProtocol &protocol) {
+  CallProtocol res;
+  res.udp_p2p = protocol.udp_p2p_;
+  res.udp_reflector = protocol.udp_reflector_;
+  res.min_layer = protocol.min_layer_;
+  res.max_layer = protocol.max_layer_;
+  return res;
+}
+tl_object_ptr<td_api::callProtocol> CallProtocol::as_td_api() const {
+  return make_tl_object<td_api::callProtocol>(udp_p2p, udp_reflector, min_layer, max_layer);
+}
+
+CallConnection CallConnection::from_telegram_api(const telegram_api::phoneConnection &connection) {
+  CallConnection res;
+  res.id = connection.id_;
+  res.ip = connection.ip_;
+  res.ipv6 = connection.ipv6_;
+  res.port = connection.port_;
+  res.peer_tag = connection.peer_tag_.as_slice().str();
+  return res;
+}
+tl_object_ptr<telegram_api::phoneConnection> CallConnection::as_telegram_api() const {
+  return make_tl_object<telegram_api::phoneConnection>(id, ip, ipv6, port, BufferSlice(peer_tag));
+}
+tl_object_ptr<td_api::callConnection> CallConnection::as_td_api() const {
+  return make_tl_object<td_api::callConnection>(id, ip, ipv6, port, peer_tag);
+}
+
+// CallState
+tl_object_ptr<td_api::CallState> CallState::as_td_api() const {
+  switch (type) {
+    case Type::Pending:
+      return make_tl_object<td_api::callStatePending>(is_created, is_received);
+    case Type::ExchangingKey:
+      return make_tl_object<td_api::callStateExchangingKeys>();
+    case Type::Ready: {
+      std::vector<tl_object_ptr<td_api::callConnection>> v;
+      for (auto &c : connections) {
+        v.push_back(c.as_td_api());
+      }
+      return make_tl_object<td_api::callStateReady>(protocol.as_td_api(), std::move(v), config, key,
+                                                    vector<string>(emojis_fingerprint));
+    }
+    case Type::HangingUp:
+      return make_tl_object<td_api::callStateHangingUp>();
+    case Type::Discarded:
+      return make_tl_object<td_api::callStateDiscarded>(get_call_discard_reason_object(discard_reason), need_rating,
+                                                        need_debug_information);
+    case Type::Error:
+      CHECK(error.is_error());
+      return make_tl_object<td_api::callStateError>(make_tl_object<td_api::error>(error.code(), error.message().str()));
+    case Type::Empty:
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+// CallActor
+CallActor::CallActor(CallId call_id, ActorShared<> parent, Promise<int64> promise)
+    : parent_(std::move(parent)), call_id_promise_(std::move(promise)), local_call_id_(call_id) {
+}
+
+void CallActor::create_call(UserId user_id, tl_object_ptr<telegram_api::InputUser> &&input_user,
+                            CallProtocol &&protocol, Promise<CallId> &&promise) {
+  CHECK(state_ == State::Empty);
+  state_ = State::SendRequestQuery;
+  is_outgoing_ = true;
+  user_id_ = user_id;
+  input_user_ = std::move(input_user);
+  call_state_.protocol = std::move(protocol);
+  call_state_.type = CallState::Type::Pending;
+  call_state_.is_received = false;
+  call_state_need_flush_ = true;
+  loop();
+  promise.set_value(CallId(local_call_id_));
+}
+
+void CallActor::discard_call(bool is_disconnected, int32 duration, int64 connection_id, Promise<> promise) {
+  promise.set_value(Unit());
+  if (state_ == State::Discarded || state_ == State::WaitDiscardResult || state_ == State::SendDiscardQuery) {
+    return;
+  }
+
+  switch (call_state_.type) {
+    case CallState::Type::Empty:
+    case CallState::Type::Pending:
+      if (is_outgoing_) {
+        call_state_.discard_reason = CallDiscardReason::Missed;
+      } else {
+        call_state_.discard_reason = CallDiscardReason::Declined;
+      }
+      break;
+    case CallState::Type::ExchangingKey:
+      call_state_.discard_reason = is_disconnected ? CallDiscardReason::Disconnected : CallDiscardReason::HungUp;
+      break;
+    case CallState::Type::Ready:
+      call_state_.discard_reason = is_disconnected ? CallDiscardReason::Disconnected : CallDiscardReason::HungUp;
+      duration_ = duration;
+      connection_id_ = connection_id;
+      break;
+    case CallState::Type::HangingUp:
+    case CallState::Type::Discarded:
+    case CallState::Type::Error:
+    default:
+      UNREACHABLE();
+      return;
+  }
+
+  call_state_.type = CallState::Type::HangingUp;
+  call_state_need_flush_ = true;
+
+  state_ = State::SendDiscardQuery;
+  loop();
+}
+
+void CallActor::accept_call(CallProtocol &&protocol, Promise<> promise) {
+  if (state_ != State::SendAcceptQuery) {
+    return promise.set_error(Status::Error(400, "Unexpected acceptCall"));
+  }
+  is_accepted_ = true;
+  call_state_.protocol = std::move(protocol);
+  promise.set_value(Unit());
+  loop();
+}
+
+void CallActor::rate_call(int32 rating, string comment, Promise<> promise) {
+  if (!call_state_.need_rating) {
+    return promise.set_error(Status::Error(400, "Unexpected sendCallRating"));
+  }
+  promise.set_value(Unit());
+  auto tl_query = telegram_api::phone_setCallRating(get_input_phone_call(), rating, std::move(comment));
+  auto query = G()->net_query_creator().create(create_storer(tl_query));
+  send_with_promise(std::move(query), PromiseCreator::lambda([actor_id = actor_id(this)](NetQueryPtr net_query) {
+                      send_closure(actor_id, &CallActor::on_set_rating_query_result, std::move(net_query));
+                    }));
+  loop();
+}
+
+void CallActor::on_set_rating_query_result(NetQueryPtr net_query) {
+  auto res = fetch_result<telegram_api::phone_setCallRating>(std::move(net_query));
+  if (res.is_error()) {
+    return on_error(res.move_as_error());
+  }
+  call_state_.need_rating = false;
+  send_closure(G()->updates_manager(), &UpdatesManager::on_get_updates, res.move_as_ok());
+}
+
+void CallActor::send_call_debug_information(string data, Promise<> promise) {
+  if (!call_state_.need_debug_information) {
+    return promise.set_error(Status::Error(400, "Unexpected sendCallDebugInformation"));
+  }
+  promise.set_value(Unit());
+  auto tl_query = telegram_api::phone_saveCallDebug(get_input_phone_call(),
+                                                    make_tl_object<telegram_api::dataJSON>(std::move(data)));
+  auto query = G()->net_query_creator().create(create_storer(tl_query));
+  send_with_promise(std::move(query), PromiseCreator::lambda([actor_id = actor_id(this)](NetQueryPtr net_query) {
+                      send_closure(actor_id, &CallActor::on_set_debug_query_result, std::move(net_query));
+                    }));
+  loop();
+}
+
+void CallActor::on_set_debug_query_result(NetQueryPtr net_query) {
+  auto res = fetch_result<telegram_api::phone_saveCallDebug>(std::move(net_query));
+  if (res.is_error()) {
+    return on_error(res.move_as_error());
+  }
+  call_state_.need_debug_information = false;
+}
+
+//Updates
+//phoneCallEmpty#5366c915 id:long = PhoneCall;
+//phoneCallWaiting#1b8f4ad1 flags:# id:long access_hash:long date:int admin_id:int participant_id:int protocol:PhoneCallProtocol receive_date:flags.0?int = PhoneCall;
+
+// Requests
+//phone.discardCall#78d413a6 peer:InputPhoneCall duration:int reason:PhoneCallDiscardReason connection_id:long = Updates;
+void CallActor::update_call(tl_object_ptr<telegram_api::PhoneCall> call) {
+  Status status;
+  downcast_call(*call, [&](auto &call) { status = this->do_update_call(call); });
+  if (status.is_error()) {
+    on_error(std::move(status));
+  }
+  loop();
+}
+
+void CallActor::update_call_inner(tl_object_ptr<telegram_api::phone_phoneCall> call) {
+  send_closure(G()->contacts_manager(), &ContactsManager::on_get_users, std::move(call->users_));
+  update_call(std::move(call->phone_call_));
+}
+
+Status CallActor::do_update_call(telegram_api::phoneCallEmpty &call) {
+  return Status::Error(400, "Call is finished");
+}
+
+//phoneCallWaiting#1b8f4ad1 flags:# id:long access_hash:long date:int admin_id:int participant_id:int protocol:PhoneCallProtocol receive_date:flags.0?int = PhoneCall;
+Status CallActor::do_update_call(telegram_api::phoneCallWaiting &call) {
+  if (state_ != State::WaitRequestResult && state_ != State::WaitAcceptResult) {
+    return Status::Error(500, PSLICE() << "Drop unexpected " << to_string(call));
+  }
+
+  if (state_ == State::WaitAcceptResult) {
+    call_state_.type = CallState::Type::ExchangingKey;
+    call_state_need_flush_ = true;
+    cancel_timeout();
+  } else {
+    if ((call.flags_ & telegram_api::phoneCallWaiting::RECEIVE_DATE_MASK) != 0) {
+      call_state_.is_received = true;
+      call_state_need_flush_ = true;
+      int32 call_ring_timeout_ms = G()->shared_config().get_option_integer("call_ring_timeout_ms", 90000);
+      set_timeout_in(call_ring_timeout_ms * 0.001);
+    }
+  }
+
+  call_id_ = call.id_;
+  call_access_hash_ = call.access_hash_;
+  call_admin_id_ = call.admin_id_;
+  call_participant_id_ = call.participant_id_;
+  if (call_id_promise_) {
+    call_id_promise_.set_value(std::move(call.id_));
+  }
+
+  if (!call_state_.is_created) {
+    call_state_.is_created = true;
+    call_state_need_flush_ = true;
+  }
+
+  return Status::OK();
+}
+
+//phoneCallRequested#83761ce4 id:long access_hash:long date:int admin_id:int participant_id:int g_a_hash:bytes protocol:PhoneCallProtocol = PhoneCall;
+Status CallActor::do_update_call(telegram_api::phoneCallRequested &call) {
+  if (state_ != State::Empty) {
+    return Status::Error(500, PSLICE() << "Drop unexpected " << to_string(call));
+  }
+  call_id_ = call.id_;
+  call_access_hash_ = call.access_hash_;
+  call_admin_id_ = call.admin_id_;
+  call_participant_id_ = call.participant_id_;
+  if (call_id_promise_) {
+    call_id_promise_.set_value(std::move(call.id_));
+  }
+
+  dh_handshake_.set_g_a_hash(call.g_a_hash_.as_slice());
+  state_ = State::SendAcceptQuery;
+
+  call_state_.type = CallState::Type::Pending;
+  call_state_.is_created = true;
+  call_state_.is_received = true;
+  call_state_need_flush_ = true;
+
+  send_received_query();
+  return Status::OK();
+}
+
+tl_object_ptr<telegram_api::inputPhoneCall> CallActor::get_input_phone_call() {
+  CHECK(call_id_ != 0);
+  return make_tl_object<telegram_api::inputPhoneCall>(call_id_, call_access_hash_);
+}
+
+//phoneCallAccepted#6d003d3f id:long access_hash:long date:int admin_id:int participant_id:int g_b:bytes protocol:PhoneCallProtocol = PhoneCall;
+Status CallActor::do_update_call(telegram_api::phoneCallAccepted &call) {
+  if (state_ != State::WaitRequestResult) {
+    return Status::Error(500, PSLICE() << "Drop unexpected " << to_string(call));
+  }
+
+  dh_handshake_.set_g_a(call.g_b_.as_slice());
+  TRY_STATUS(dh_handshake_.run_checks(DhCache::instance()));
+  std::tie(call_state_.key_fingerprint, call_state_.key) = dh_handshake_.gen_key();
+  state_ = State::SendConfirmQuery;
+  call_state_.type = CallState::Type::ExchangingKey;
+  call_state_need_flush_ = true;
+  cancel_timeout();
+  return Status::OK();
+}
+
+//phoneCall#ffe6ab67 id:long access_hash:long date:int admin_id:int participant_id:int g_a_or_b:bytes key_fingerprint:long protocol:PhoneCallProtocol connection:PhoneConnection alternative_connections:Vector<PhoneConnection> start_date:int = PhoneCall;
+Status CallActor::do_update_call(telegram_api::phoneCall &call) {
+  if (state_ != State::WaitAcceptResult && state_ != State::WaitConfirmResult) {
+    return Status::Error(500, PSLICE() << "Drop unexpected " << to_string(call));
+  }
+
+  if (state_ == State::WaitAcceptResult) {
+    dh_handshake_.set_g_a(call.g_a_or_b_.as_slice());
+    TRY_STATUS(dh_handshake_.run_checks(DhCache::instance()));
+    std::tie(call_state_.key_fingerprint, call_state_.key) = dh_handshake_.gen_key();
+  }
+  if (call_state_.key_fingerprint != call.key_fingerprint_) {
+    return Status::Error(400, "Key fingerprints mismatch");
+  }
+
+  call_state_.emojis_fingerprint =
+      get_emojis_fingerprint(call_state_.key, is_outgoing_ ? dh_handshake_.get_g_b() : dh_handshake_.get_g_a());
+
+  call_state_.connections.push_back(CallConnection::from_telegram_api(*call.connection_));
+  for (auto &connection : call.alternative_connections_) {
+    call_state_.connections.push_back(CallConnection::from_telegram_api(*connection));
+  }
+  call_state_.protocol = CallProtocol::from_telegram_api(*call.protocol_);
+  call_state_.type = CallState::Type::Ready;
+  call_state_need_flush_ = true;
+
+  return Status::OK();
+}
+
+//phoneCallDiscarded#50ca4de1 flags:# need_rating:flags.2?true need_debug:flags.3?true id:long reason:flags.0?PhoneCallDiscardReason duration:flags.1?int = PhoneCall;
+Status CallActor::do_update_call(telegram_api::phoneCallDiscarded &call) {
+  state_ = State::Discarded;
+
+  auto reason = get_call_discard_reason(call.reason_);
+  if (call_state_.discard_reason == CallDiscardReason::Empty || reason != CallDiscardReason::Empty) {
+    call_state_.discard_reason = reason;
+  }
+  if (call_state_.type != CallState::Type::Error) {
+    call_state_.need_rating = call.need_rating_;
+    call_state_.need_debug_information = call.need_debug_;
+    call_state_.type = CallState::Type::Discarded;
+    call_state_need_flush_ = true;
+  }
+  return Status::OK();
+}
+
+bool CallActor::load_dh_config() {
+  if (dh_config_ready_) {
+    return true;
+  }
+  if (!dh_config_query_sent_) {
+    dh_config_query_sent_ = true;
+    do_load_dh_config(PromiseCreator::lambda([actor_id = actor_id(this)](Result<std::shared_ptr<DhConfig>> dh_config) {
+      send_closure(actor_id, &CallActor::on_dh_config, std::move(dh_config), false);
+    }));
+  }
+  return false;
+}
+
+void CallActor::on_error(Status status) {
+  CHECK(status.is_error());
+
+  if (state_ == State::WaitDiscardResult || state_ == State::Discarded) {
+    state_ = State::Discarded;
+  } else {
+    state_ = State::SendDiscardQuery;
+    call_state_.discard_reason =
+        call_state_.type == CallState::Type::Pending ? CallDiscardReason::Missed : CallDiscardReason::Disconnected;
+  }
+
+  call_state_.type = CallState::Type::Error;
+  call_state_.error = std::move(status);
+  call_state_need_flush_ = true;
+}
+
+void CallActor::on_dh_config(Result<std::shared_ptr<DhConfig>> r_dh_config, bool dummy) {
+  if (r_dh_config.is_error()) {
+    return on_error(r_dh_config.move_as_error());
+  }
+  dh_config_ready_ = true;
+  dh_config_ = r_dh_config.move_as_ok();
+  yield();
+}
+
+void CallActor::do_load_dh_config(Promise<std::shared_ptr<DhConfig>> promise) {
+  //TODO: move to external actor
+  auto dh_config = G()->get_dh_config();
+  int32 version = 0;
+  if (dh_config) {
+    version = dh_config->version;
+  }
+  int random_length = 0;
+  telegram_api::messages_getDhConfig tl_query(version, random_length);
+  auto query = G()->net_query_creator().create(create_storer(tl_query));
+  send_with_promise(std::move(query),
+                    PromiseCreator::lambda([actor_id = actor_id(this), old_dh_config = std::move(dh_config),
+                                            promise = std::move(promise)](Result<NetQueryPtr> result_query) mutable {
+                      promise.set_result([&]() -> Result<std::shared_ptr<DhConfig>> {
+                        TRY_RESULT(query, std::move(result_query));
+                        TRY_RESULT(new_dh_config, fetch_result<telegram_api::messages_getDhConfig>(std::move(query)));
+                        if (new_dh_config->get_id() == telegram_api::messages_dhConfig::ID) {
+                          auto dh = move_tl_object_as<telegram_api::messages_dhConfig>(new_dh_config);
+                          auto dh_config = std::make_shared<DhConfig>();
+                          dh_config->version = dh->version_;
+                          dh_config->prime = dh->p_.as_slice().str();
+                          dh_config->g = dh->g_;
+                          G()->set_dh_config(dh_config);
+                          return std::move(dh_config);
+                        }
+                        if (old_dh_config) {
+                          return std::move(old_dh_config);
+                        }
+                        return Status::Error(500, "Can't load DhConfig");
+                      }());
+                    }));
+}
+
+void CallActor::send_received_query() {
+  auto tl_query = telegram_api::phone_receivedCall(get_input_phone_call());
+  auto query = G()->net_query_creator().create(create_storer(tl_query));
+  send_with_promise(std::move(query), PromiseCreator::lambda([actor_id = actor_id(this)](NetQueryPtr net_query) {
+                      send_closure(actor_id, &CallActor::on_received_query_result, std::move(net_query));
+                    }));
+}
+
+void CallActor::on_received_query_result(NetQueryPtr net_query) {
+  auto res = fetch_result<telegram_api::phone_receivedCall>(std::move(net_query));
+  if (res.is_error()) {
+    return on_error(res.move_as_error());
+  }
+}
+
+//phone.requestCall#5b95b3d4 user_id:InputUser random_id:int g_a_hash:bytes protocol:PhoneCallProtocol = phone.PhoneCall;
+void CallActor::try_send_request_query() {
+  if (!load_dh_config()) {
+    return;
+  }
+  dh_handshake_.set_config(dh_config_->g, dh_config_->prime);
+  CHECK(input_user_ != nullptr);
+  auto tl_query = telegram_api::phone_requestCall(std::move(input_user_), Random::secure_int32(),
+                                                  BufferSlice(dh_handshake_.get_g_b_hash()),
+                                                  call_state_.protocol.as_telegram_api());
+  auto query = G()->net_query_creator().create(create_storer(tl_query));
+  state_ = State::WaitRequestResult;
+  send_with_promise(std::move(query), PromiseCreator::lambda([actor_id = actor_id(this)](NetQueryPtr net_query) {
+                      send_closure(actor_id, &CallActor::on_request_query_result, std::move(net_query));
+                    }));
+  int32 call_receive_timeout_ms = G()->shared_config().get_option_integer("call_receive_timeout_ms", 20000);
+  set_timeout_in(call_receive_timeout_ms * 0.001);
+}
+
+void CallActor::on_request_query_result(NetQueryPtr net_query) {
+  auto res = fetch_result<telegram_api::phone_requestCall>(std::move(net_query));
+  if (res.is_error()) {
+    return on_error(res.move_as_error());
+  }
+  update_call_inner(res.move_as_ok());
+}
+
+//phone.acceptCall#3bd2b4a0 peer:InputPhoneCall g_b:bytes protocol:PhoneCallProtocol = phone.PhoneCall;
+void CallActor::try_send_accept_query() {
+  if (!load_dh_config()) {
+    return;
+  }
+  if (!is_accepted_) {
+    return;
+  }
+  dh_handshake_.set_config(dh_config_->g, dh_config_->prime);
+  auto tl_query = telegram_api::phone_acceptCall(get_input_phone_call(), BufferSlice(dh_handshake_.get_g_b()),
+                                                 call_state_.protocol.as_telegram_api());
+  auto query = G()->net_query_creator().create(create_storer(tl_query));
+  state_ = State::WaitAcceptResult;
+  send_with_promise(std::move(query), PromiseCreator::lambda([actor_id = actor_id(this)](NetQueryPtr net_query) {
+                      send_closure(actor_id, &CallActor::on_accept_query_result, std::move(net_query));
+                    }));
+}
+
+void CallActor::on_accept_query_result(NetQueryPtr net_query) {
+  auto res = fetch_result<telegram_api::phone_acceptCall>(std::move(net_query));
+  if (res.is_error()) {
+    return on_error(res.move_as_error());
+  }
+  update_call_inner(res.move_as_ok());
+}
+
+//phone.confirmCall#2efe1722 peer:InputPhoneCall g_a:bytes key_fingerprint:long protocol:PhoneCallProtocol = phone.PhoneCall;
+void CallActor::try_send_confirm_query() {
+  if (!load_dh_config()) {
+    return;
+  }
+  auto tl_query = telegram_api::phone_confirmCall(get_input_phone_call(), BufferSlice(dh_handshake_.get_g_b()),
+                                                  call_state_.key_fingerprint, call_state_.protocol.as_telegram_api());
+  auto query = G()->net_query_creator().create(create_storer(tl_query));
+  state_ = State::WaitConfirmResult;
+  send_with_promise(std::move(query), PromiseCreator::lambda([actor_id = actor_id(this)](NetQueryPtr net_query) {
+                      send_closure(actor_id, &CallActor::on_confirm_query_result, std::move(net_query));
+                    }));
+}
+
+void CallActor::on_confirm_query_result(NetQueryPtr net_query) {
+  auto res = fetch_result<telegram_api::phone_confirmCall>(std::move(net_query));
+  if (res.is_error()) {
+    return on_error(res.move_as_error());
+  }
+  update_call_inner(res.move_as_ok());
+}
+
+void CallActor::try_send_discard_query() {
+  if (call_id_ == 0) {
+    state_ = State::Discarded;
+    yield();
+    return;
+  }
+  auto tl_query =
+      telegram_api::phone_discardCall(get_input_phone_call(), duration_,
+                                      get_input_phone_call_discard_reason(call_state_.discard_reason), connection_id_);
+  auto query = G()->net_query_creator().create(create_storer(tl_query));
+  state_ = State::WaitDiscardResult;
+  send_with_promise(std::move(query), PromiseCreator::lambda([actor_id = actor_id(this)](NetQueryPtr net_query) {
+                      send_closure(actor_id, &CallActor::on_discard_query_result, std::move(net_query));
+                    }));
+}
+
+void CallActor::on_discard_query_result(NetQueryPtr net_query) {
+  auto res = fetch_result<telegram_api::phone_discardCall>(std::move(net_query));
+  if (res.is_error()) {
+    return on_error(res.move_as_error());
+  }
+  send_closure(G()->updates_manager(), &UpdatesManager::on_get_updates, res.move_as_ok());
+}
+
+void CallActor::flush_call_state() {
+  if (call_state_need_flush_) {
+    if (call_state_.type == CallState::Type::Ready && !call_state_has_config_) {
+      return;
+    }
+    call_state_need_flush_ = false;
+
+    // can't call const function
+    // send_closure(G()->contacts_manager(), &ContactsManager::get_user_id_object, user_id_, "flush_call_state");
+    send_closure(G()->td(), &Td::send_update,
+                 make_tl_object<td_api::updateCall>(
+                     make_tl_object<td_api::call>(local_call_id_.get(), is_outgoing_ ? user_id_.get() : call_admin_id_,
+                                                  is_outgoing_, call_state_.as_td_api())));
+  }
+}
+
+void CallActor::start_up() {
+  auto tl_query = telegram_api::phone_getCallConfig();
+  auto query = G()->net_query_creator().create(create_storer(tl_query));
+  send_with_promise(std::move(query), PromiseCreator::lambda([actor_id = actor_id(this)](NetQueryPtr net_query) {
+                      send_closure(actor_id, &CallActor::on_get_call_config_result, std::move(net_query));
+                    }));
+}
+
+void CallActor::on_get_call_config_result(NetQueryPtr net_query) {
+  auto res = fetch_result<telegram_api::phone_getCallConfig>(std::move(net_query));
+  if (res.is_error()) {
+    return on_error(res.move_as_error());
+  }
+  call_state_.config = res.ok()->data_;
+  call_state_has_config_ = true;
+}
+
+void CallActor::loop() {
+  flush_call_state();
+  switch (state_) {
+    case State::SendRequestQuery:
+      try_send_request_query();
+      break;
+    case State::SendAcceptQuery:
+      try_send_accept_query();
+      break;
+    case State::SendConfirmQuery:
+      try_send_confirm_query();
+      break;
+    case State::SendDiscardQuery:
+      try_send_discard_query();
+      break;
+    case State::Discarded: {
+      if (call_state_.type == CallState::Type::Discarded &&
+          (call_state_.need_rating || call_state_.need_debug_information)) {
+        break;
+      }
+      LOG(INFO) << "Close call " << local_call_id_;
+      stop();
+      break;
+    }
+    default:
+      break;
+  }
+}
+
+void CallActor::timeout_expired() {
+  on_error(Status::Error(4005000, "Call timeout expired"));
+  yield();
+}
+
+void CallActor::on_result(NetQueryPtr query) {
+  auto token = get_link_token();
+  container_.extract(token).set_value(std::move(query));
+  yield();  // Call loop AFTER all events from the promise are executed
+}
+
+void CallActor::send_with_promise(NetQueryPtr query, Promise<NetQueryPtr> promise) {
+  auto id = container_.create(std::move(promise));
+  G()->net_query_dispatcher().dispatch_with_callback(std::move(query), actor_shared(this, id));
+}
+
+vector<string> CallActor::get_emojis_fingerprint(const string &key, const string &g_a) {
+  string str = key + g_a;
+  unsigned char sha256_buf[32];
+  sha256(str, {sha256_buf, 32});
+
+  vector<string> result;
+  result.reserve(4);
+  for (int i = 0; i < 4; i++) {
+    uint64 num =
+        (static_cast<uint64>(sha256_buf[8 * i + 0]) << 56) | (static_cast<uint64>(sha256_buf[8 * i + 1]) << 48) |
+        (static_cast<uint64>(sha256_buf[8 * i + 2]) << 40) | (static_cast<uint64>(sha256_buf[8 * i + 3]) << 32) |
+        (static_cast<uint64>(sha256_buf[8 * i + 4]) << 24) | (static_cast<uint64>(sha256_buf[8 * i + 5]) << 16) |
+        (static_cast<uint64>(sha256_buf[8 * i + 6]) << 8) | (static_cast<uint64>(sha256_buf[8 * i + 7]));
+    result.push_back(get_emoji_fingerprint(num));
+  }
+  return result;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/CallActor.h b/libs/tdlib/td/td/telegram/CallActor.h
new file mode 100644
index 0000000000..02960bb3f1
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/CallActor.h
@@ -0,0 +1,175 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/mtproto/crypto.h"
+
+#include "td/telegram/CallDiscardReason.h"
+#include "td/telegram/CallId.h"
+#include "td/telegram/DhConfig.h"
+#include "td/telegram/net/NetQuery.h"
+#include "td/telegram/UserId.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/utils/Container.h"
+#include "td/utils/Status.h"
+
+#include <memory>
+
+namespace td {
+struct CallProtocol {
+  bool udp_p2p{true};
+  bool udp_reflector{true};
+  int32 min_layer{65};
+  int32 max_layer{65};
+
+  static CallProtocol from_telegram_api(const telegram_api::phoneCallProtocol &protocol);
+  tl_object_ptr<telegram_api::phoneCallProtocol> as_telegram_api() const;
+  static CallProtocol from_td_api(const td_api::callProtocol &protocol);
+  tl_object_ptr<td_api::callProtocol> as_td_api() const;
+};
+
+struct CallConnection {
+  int64 id;
+  string ip;
+  string ipv6;
+  int32 port;
+  string peer_tag;
+
+  static CallConnection from_telegram_api(const telegram_api::phoneConnection &connection);
+  tl_object_ptr<telegram_api::phoneConnection> as_telegram_api() const;
+  tl_object_ptr<td_api::callConnection> as_td_api() const;
+};
+
+struct CallState {
+  enum class Type { Empty, Pending, ExchangingKey, Ready, HangingUp, Discarded, Error } type{Type::Empty};
+
+  CallProtocol protocol;
+  std::vector<CallConnection> connections;
+  CallDiscardReason discard_reason{CallDiscardReason::Empty};
+  bool is_created{false};
+  bool is_received{false};
+  bool need_debug_information{false};
+  bool need_rating{false};
+
+  int64 key_fingerprint{0};
+  string key;
+  string config;
+  vector<string> emojis_fingerprint;
+
+  Status error;
+
+  tl_object_ptr<td_api::CallState> as_td_api() const;
+};
+
+class CallActor : public NetQueryCallback {
+ public:
+  CallActor(CallId call_id, ActorShared<> parent, Promise<int64> promise);
+
+  void create_call(UserId user_id, tl_object_ptr<telegram_api::InputUser> &&input_user, CallProtocol &&protocol,
+                   Promise<CallId> &&promise);
+  void discard_call(bool is_disconnected, int32 duration, int64 connection_id, Promise<> promise);
+  void accept_call(CallProtocol &&protocol, Promise<> promise);
+  void rate_call(int32 rating, string comment, Promise<> promise);
+  void send_call_debug_information(string data, Promise<> promise);
+
+  void update_call(tl_object_ptr<telegram_api::PhoneCall> call);
+
+ private:
+  void update_call_inner(tl_object_ptr<telegram_api::phone_phoneCall> call);
+  ActorShared<> parent_;
+  Promise<int64> call_id_promise_;
+
+  DhHandshake dh_handshake_;
+  std::shared_ptr<DhConfig> dh_config_;
+  bool dh_config_query_sent_{false};
+  bool dh_config_ready_{false};
+
+  int32 duration_{0};
+  int64 connection_id_{0};
+
+  enum class State {
+    Empty,
+    SendRequestQuery,
+    WaitRequestResult,
+    SendAcceptQuery,
+    WaitAcceptResult,
+    SendConfirmQuery,
+    WaitConfirmResult,
+    SendDiscardQuery,
+    WaitDiscardResult,
+    Discarded
+  } state_{State::Empty};
+  bool is_accepted_{false};
+
+  bool is_outgoing_{false};
+  UserId user_id_;
+  tl_object_ptr<telegram_api::InputUser> input_user_;
+
+  CallId local_call_id_;
+  int64 call_id_{0};
+  int64 call_access_hash_{0};
+  int32 call_admin_id_{0};
+  int32 call_participant_id_{0};
+
+  CallState call_state_;
+  bool call_state_need_flush_{false};
+  bool call_state_has_config_{false};
+
+  tl_object_ptr<telegram_api::inputPhoneCall> get_input_phone_call();
+  bool load_dh_config();
+  void on_dh_config(Result<std::shared_ptr<DhConfig>> r_dh_config, bool dummy);
+  void do_load_dh_config(Promise<std::shared_ptr<DhConfig>> promise);
+
+  Status do_update_call(telegram_api::phoneCallEmpty &call);
+  Status do_update_call(telegram_api::phoneCallWaiting &call);
+  Status do_update_call(telegram_api::phoneCallRequested &call);
+  Status do_update_call(telegram_api::phoneCallAccepted &call);
+  Status do_update_call(telegram_api::phoneCall &call);
+  Status do_update_call(telegram_api::phoneCallDiscarded &call);
+
+  void send_received_query();
+  void on_received_query_result(NetQueryPtr net_query);
+
+  void try_send_request_query();
+  void on_request_query_result(NetQueryPtr net_query);
+
+  void try_send_accept_query();
+  void on_accept_query_result(NetQueryPtr net_query);
+
+  void try_send_confirm_query();
+  void on_confirm_query_result(NetQueryPtr net_query);
+
+  void try_send_discard_query();
+  void on_discard_query_result(NetQueryPtr net_query);
+
+  void on_set_rating_query_result(NetQueryPtr net_query);
+  void on_set_debug_query_result(NetQueryPtr net_query);
+
+  void on_get_call_config_result(NetQueryPtr net_query);
+
+  void flush_call_state();
+
+  static vector<string> get_emojis_fingerprint(const string &key, const string &g_a);
+
+  void start_up() override;
+  void loop() override;
+
+  Container<Promise<NetQueryPtr>> container_;
+  void on_result(NetQueryPtr query) override;
+  void send_with_promise(NetQueryPtr query, Promise<NetQueryPtr> promise);
+
+  void timeout_expired() override;
+
+  void on_error(Status status);
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/CallDiscardReason.cpp b/libs/tdlib/td/td/telegram/CallDiscardReason.cpp
new file mode 100644
index 0000000000..2b6fbbc5d7
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/CallDiscardReason.cpp
@@ -0,0 +1,71 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/CallDiscardReason.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/utils/logging.h"
+
+namespace td {
+
+CallDiscardReason get_call_discard_reason(const tl_object_ptr<telegram_api::PhoneCallDiscardReason> &reason) {
+  if (reason == nullptr) {
+    return CallDiscardReason::Empty;
+  }
+  switch (reason->get_id()) {
+    case telegram_api::phoneCallDiscardReasonMissed::ID:
+      return CallDiscardReason::Missed;
+    case telegram_api::phoneCallDiscardReasonDisconnect::ID:
+      return CallDiscardReason::Disconnected;
+    case telegram_api::phoneCallDiscardReasonHangup::ID:
+      return CallDiscardReason::HungUp;
+    case telegram_api::phoneCallDiscardReasonBusy::ID:
+      return CallDiscardReason::Declined;
+    default:
+      UNREACHABLE();
+      return CallDiscardReason::Empty;
+  }
+}
+
+tl_object_ptr<telegram_api::PhoneCallDiscardReason> get_input_phone_call_discard_reason(CallDiscardReason reason) {
+  switch (reason) {
+    case CallDiscardReason::Empty:
+      return nullptr;
+    case CallDiscardReason::Missed:
+      return make_tl_object<telegram_api::phoneCallDiscardReasonMissed>();
+    case CallDiscardReason::Disconnected:
+      return make_tl_object<telegram_api::phoneCallDiscardReasonDisconnect>();
+    case CallDiscardReason::HungUp:
+      return make_tl_object<telegram_api::phoneCallDiscardReasonHangup>();
+    case CallDiscardReason::Declined:
+      return make_tl_object<telegram_api::phoneCallDiscardReasonBusy>();
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+tl_object_ptr<td_api::CallDiscardReason> get_call_discard_reason_object(CallDiscardReason reason) {
+  switch (reason) {
+    case CallDiscardReason::Empty:
+      return make_tl_object<td_api::callDiscardReasonEmpty>();
+    case CallDiscardReason::Missed:
+      return make_tl_object<td_api::callDiscardReasonMissed>();
+    case CallDiscardReason::Disconnected:
+      return make_tl_object<td_api::callDiscardReasonDisconnected>();
+    case CallDiscardReason::HungUp:
+      return make_tl_object<td_api::callDiscardReasonHungUp>();
+    case CallDiscardReason::Declined:
+      return make_tl_object<td_api::callDiscardReasonDeclined>();
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/CallDiscardReason.h b/libs/tdlib/td/td/telegram/CallDiscardReason.h
new file mode 100644
index 0000000000..d4c00e5214
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/CallDiscardReason.h
@@ -0,0 +1,31 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/tl/TlObject.h"
+
+#include "td/utils/int_types.h"
+
+namespace td {
+
+namespace td_api {
+class CallDiscardReason;
+}  // namespace td_api
+
+namespace telegram_api {
+class PhoneCallDiscardReason;
+}  // namespace telegram_api
+
+enum class CallDiscardReason : int32 { Empty, Missed, Disconnected, HungUp, Declined };
+
+CallDiscardReason get_call_discard_reason(const tl_object_ptr<telegram_api::PhoneCallDiscardReason> &reason);
+
+tl_object_ptr<telegram_api::PhoneCallDiscardReason> get_input_phone_call_discard_reason(CallDiscardReason reason);
+
+tl_object_ptr<td_api::CallDiscardReason> get_call_discard_reason_object(CallDiscardReason reason);
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/CallId.h b/libs/tdlib/td/td/telegram/CallId.h
new file mode 100644
index 0000000000..227e2240d9
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/CallId.h
@@ -0,0 +1,57 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+
+#include "td/utils/common.h"
+#include "td/utils/StringBuilder.h"
+
+#include <functional>
+#include <type_traits>
+
+namespace td {
+class CallId {
+ public:
+  CallId() = default;
+
+  explicit CallId(int32 call_id) : id(call_id) {
+  }
+
+  template <class T, typename = std::enable_if_t<std::is_convertible<T, int32>::value>>
+  CallId(T call_id) = delete;
+
+  bool is_valid() const {
+    return id != 0;
+  }
+
+  int32 get() const {
+    return id;
+  }
+
+  auto as_td_api() const {
+    return make_tl_object<td_api::callId>(id);
+  }
+
+  bool operator==(const CallId &other) const {
+    return id == other.id;
+  }
+
+ private:
+  int32 id{0};
+};
+
+struct CallIdHash {
+  std::size_t operator()(CallId call_id) const {
+    return std::hash<int32>()(call_id.get());
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &sb, const CallId call_id) {
+  return sb << "CallId(" << call_id.get() << ")";
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/CallManager.cpp b/libs/tdlib/td/td/telegram/CallManager.cpp
new file mode 100644
index 0000000000..4b17b26de4
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/CallManager.cpp
@@ -0,0 +1,155 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/CallManager.h"
+
+#include "td/telegram/Global.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+
+#include "td/telegram/telegram_api.hpp"
+
+#include <limits>
+
+namespace td {
+
+CallManager::CallManager(ActorShared<> parent) : parent_(std::move(parent)) {
+}
+
+void CallManager::update_call(Update call) {
+  int64 call_id = 0;
+  downcast_call(*call->phone_call_, [&](auto &update) { call_id = update.id_; });
+
+  auto &info = call_info_[call_id];
+
+  if (!info.call_id.is_valid() && call->phone_call_->get_id() == telegram_api::phoneCallRequested::ID) {
+    info.call_id = create_call_actor();
+  }
+
+  if (!info.call_id.is_valid()) {
+    info.updates.push_back(std::move(call));
+    return;
+  }
+
+  auto actor = get_call_actor(info.call_id);
+  if (actor.empty()) {
+    LOG(WARNING) << "Drop update: " << to_string(call);
+  }
+  send_closure(actor, &CallActor::update_call, std::move(call->phone_call_));
+}
+
+void CallManager::create_call(UserId user_id, tl_object_ptr<telegram_api::InputUser> &&input_user,
+                              CallProtocol &&protocol, Promise<CallId> promise) {
+  LOG(INFO) << "Create call with " << user_id;
+  auto call_id = create_call_actor();
+  auto actor = get_call_actor(call_id);
+  CHECK(!actor.empty());
+  send_closure(actor, &CallActor::create_call, user_id, std::move(input_user), std::move(protocol), std::move(promise));
+}
+
+void CallManager::discard_call(CallId call_id, bool is_disconnected, int32 duration, int64 connection_id,
+                               Promise<> promise) {
+  auto actor = get_call_actor(call_id);
+  if (actor.empty()) {
+    return promise.set_error(Status::Error(400, "Call not found"));
+  }
+  send_closure(actor, &CallActor::discard_call, is_disconnected, duration, connection_id, std::move(promise));
+}
+
+void CallManager::accept_call(CallId call_id, CallProtocol &&protocol, Promise<> promise) {
+  auto actor = get_call_actor(call_id);
+  if (actor.empty()) {
+    return promise.set_error(Status::Error(400, "Call not found"));
+  }
+  send_closure(actor, &CallActor::accept_call, std::move(protocol), std::move(promise));
+}
+
+void CallManager::rate_call(CallId call_id, int32 rating, string comment, Promise<> promise) {
+  auto actor = get_call_actor(call_id);
+  if (actor.empty()) {
+    return promise.set_error(Status::Error(400, "Call not found"));
+  }
+  send_closure(actor, &CallActor::rate_call, rating, std::move(comment), std::move(promise));
+}
+
+void CallManager::send_call_debug_information(CallId call_id, string data, Promise<> promise) {
+  auto actor = get_call_actor(call_id);
+  if (actor.empty()) {
+    return promise.set_error(Status::Error(400, "Call not found"));
+  }
+  send_closure(actor, &CallActor::send_call_debug_information, std::move(data), std::move(promise));
+}
+
+CallId CallManager::create_call_actor() {
+  if (next_call_id_ == std::numeric_limits<int32>::max()) {
+    next_call_id_ = 1;
+  }
+  auto id = CallId(next_call_id_++);
+  CHECK(id.is_valid());
+  auto it_flag = id_to_actor_.emplace(id, ActorOwn<CallActor>());
+  CHECK(it_flag.second);
+  LOG(INFO) << "Create CallActor: " << id;
+  auto main_promise = PromiseCreator::lambda([actor_id = actor_id(this), id](Result<int64> call_id) mutable {
+    send_closure(actor_id, &CallManager::set_call_id, id, std::move(call_id));
+  });
+  it_flag.first->second = create_actor<CallActor>(PSLICE() << "Call " << id.get(), id, actor_shared(this, id.get()),
+                                                  std::move(main_promise));
+  return id;
+}
+
+void CallManager::set_call_id(CallId call_id, Result<int64> r_server_call_id) {
+  if (r_server_call_id.is_error()) {
+    return;
+  }
+  auto server_call_id = r_server_call_id.move_as_ok();
+  auto &call_info = call_info_[server_call_id];
+  CHECK(!call_info.call_id.is_valid() || call_info.call_id == call_id);
+  call_info.call_id = call_id;
+  auto actor = get_call_actor(call_id);
+  if (actor.empty()) {
+    return;
+  }
+  for (auto &update : call_info.updates) {
+    send_closure(actor, &CallActor::update_call, std::move(update->phone_call_));
+  }
+  call_info.updates.clear();
+}
+
+ActorId<CallActor> CallManager::get_call_actor(CallId call_id) {
+  auto it = id_to_actor_.find(call_id);
+  if (it == id_to_actor_.end()) {
+    return ActorId<CallActor>();
+  }
+  return it->second.get();
+}
+
+void CallManager::hangup() {
+  close_flag_ = true;
+  for (auto &it : id_to_actor_) {
+    LOG(INFO) << "Ask close CallActor " << it.first;
+    it.second.reset();
+  }
+  if (id_to_actor_.empty()) {
+    stop();
+  }
+}
+void CallManager::hangup_shared() {
+  auto token = narrow_cast<int32>(get_link_token());
+  auto it = id_to_actor_.find(CallId(token));
+  if (it != id_to_actor_.end()) {
+    LOG(INFO) << "Close CallActor " << tag("id", it->first);
+    it->second.release();
+    id_to_actor_.erase(it);
+  } else {
+    LOG(FATAL) << "Unknown CallActor hangup " << tag("id", static_cast<int32>(token));
+  }
+  if (close_flag_ && id_to_actor_.empty()) {
+    stop();
+  }
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/CallManager.h b/libs/tdlib/td/td/telegram/CallManager.h
new file mode 100644
index 0000000000..dcfede8824
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/CallManager.h
@@ -0,0 +1,56 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/CallActor.h"
+#include "td/telegram/CallId.h"
+
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/utils/Status.h"
+
+#include <map>
+#include <unordered_map>
+
+namespace td {
+
+class CallManager : public Actor {
+ public:
+  using Update = telegram_api::object_ptr<telegram_api::updatePhoneCall>;
+  explicit CallManager(ActorShared<> parent);
+  void update_call(Update call);
+
+  void create_call(UserId user_id, tl_object_ptr<telegram_api::InputUser> &&input_user, CallProtocol &&protocol,
+                   Promise<CallId> promise);
+  void discard_call(CallId call_id, bool is_disconnected, int32 duration, int64 connection_id, Promise<> promise);
+  void accept_call(CallId call_id, CallProtocol &&protocol, Promise<> promise);
+  void rate_call(CallId call_id, int32 rating, string comment, Promise<> promise);
+  void send_call_debug_information(CallId call_id, string data, Promise<> promise);
+
+ private:
+  bool close_flag_ = false;
+  ActorShared<> parent_;
+
+  struct CallInfo {
+    CallId call_id{0};
+    std::vector<Update> updates;
+  };
+  std::map<int64, CallInfo> call_info_;
+  int32 next_call_id_{1};
+  std::unordered_map<CallId, ActorOwn<CallActor>, CallIdHash> id_to_actor_;
+
+  ActorId<CallActor> get_call_actor(CallId call_id);
+  CallId create_call_actor();
+  void set_call_id(CallId call_id, Result<int64> r_server_call_id);
+
+  void hangup() override;
+  void hangup_shared() override;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/CallbackQueriesManager.cpp b/libs/tdlib/td/td/telegram/CallbackQueriesManager.cpp
new file mode 100644
index 0000000000..46bd5e1c44
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/CallbackQueriesManager.cpp
@@ -0,0 +1,280 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/CallbackQueriesManager.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/AccessRights.h"
+#include "td/telegram/AuthManager.h"
+#include "td/telegram/ContactsManager.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/InlineQueriesManager.h"
+#include "td/telegram/MessagesManager.h"
+#include "td/telegram/Td.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/Random.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+class GetBotCallbackAnswerQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  int64 result_id_;
+  DialogId dialog_id_;
+
+ public:
+  explicit GetBotCallbackAnswerQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id, MessageId message_id, const tl_object_ptr<td_api::CallbackQueryPayload> &payload,
+            int64 result_id) {
+    result_id_ = result_id;
+    dialog_id_ = dialog_id;
+
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Read);
+    CHECK(input_peer != nullptr);
+
+    int32 flags = 0;
+    BufferSlice data;
+    CHECK(payload != nullptr);
+    switch (payload->get_id()) {
+      case td_api::callbackQueryPayloadData::ID:
+        flags = telegram_api::messages_getBotCallbackAnswer::DATA_MASK;
+        data = BufferSlice(static_cast<const td_api::callbackQueryPayloadData *>(payload.get())->data_);
+        break;
+      case td_api::callbackQueryPayloadGame::ID:
+        flags = telegram_api::messages_getBotCallbackAnswer::GAME_MASK;
+        break;
+      default:
+        UNREACHABLE();
+    }
+
+    auto net_query = G()->net_query_creator().create(create_storer(telegram_api::messages_getBotCallbackAnswer(
+        flags, false /*ignored*/, std::move(input_peer), message_id.get_server_message_id().get(), std::move(data))));
+    net_query->need_resend_on_503 = false;
+    send_query(std::move(net_query));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getBotCallbackAnswer>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->callback_queries_manager_->on_get_callback_query_answer(result_id_, result_ptr.move_as_ok());
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "GetBotCallbackAnswerQuery");
+    td->callback_queries_manager_->on_get_callback_query_answer(result_id_, nullptr);
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SetBotCallbackAnswerQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit SetBotCallbackAnswerQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int32 flags, int64 callback_query_id, const string &text, const string &url, int32 cache_time) {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_setBotCallbackAnswer(
+        flags, false /*ignored*/, callback_query_id, text, url, cache_time))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_setBotCallbackAnswer>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    if (!result) {
+      LOG(INFO) << "Sending answer to a callback query has failed";
+    }
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+CallbackQueriesManager::CallbackQueriesManager(Td *td) : td_(td) {
+}
+
+void CallbackQueriesManager::answer_callback_query(int64 callback_query_id, const string &text, bool show_alert,
+                                                   const string &url, int32 cache_time, Promise<Unit> &&promise) const {
+  int32 flags = 0;
+  if (!text.empty()) {
+    flags |= BOT_CALLBACK_ANSWER_FLAG_HAS_MESSAGE;
+  }
+  if (show_alert) {
+    flags |= BOT_CALLBACK_ANSWER_FLAG_NEED_SHOW_ALERT;
+  }
+  if (!url.empty()) {
+    flags |= BOT_CALLBACK_ANSWER_FLAG_HAS_URL;
+  }
+  td_->create_handler<SetBotCallbackAnswerQuery>(std::move(promise))
+      ->send(flags, callback_query_id, text, url, cache_time);
+}
+
+tl_object_ptr<td_api::CallbackQueryPayload> CallbackQueriesManager::get_query_payload(int32 flags, BufferSlice &&data,
+                                                                                      string &&game_short_name) {
+  bool has_data = (flags & telegram_api::updateBotCallbackQuery::DATA_MASK) != 0;
+  bool has_game = (flags & telegram_api::updateBotCallbackQuery::GAME_SHORT_NAME_MASK) != 0;
+  if (has_data == has_game) {
+    LOG(ERROR) << "Receive wrong flags " << flags << " in a callback query";
+    return nullptr;
+  }
+
+  if (has_data) {
+    return make_tl_object<td_api::callbackQueryPayloadData>(data.as_slice().str());
+  }
+  if (has_game) {
+    return make_tl_object<td_api::callbackQueryPayloadGame>(game_short_name);
+  }
+  UNREACHABLE();
+  return nullptr;
+}
+
+void CallbackQueriesManager::on_new_query(int32 flags, int64 callback_query_id, UserId sender_user_id,
+                                          DialogId dialog_id, MessageId message_id, BufferSlice &&data,
+                                          int64 chat_instance, string &&game_short_name) {
+  if (!dialog_id.is_valid()) {
+    LOG(ERROR) << "Receive new callback query in invalid " << dialog_id;
+    return;
+  }
+  if (!sender_user_id.is_valid()) {
+    LOG(ERROR) << "Receive new callback query from invalid " << sender_user_id << " in " << dialog_id;
+    return;
+  }
+  LOG_IF(ERROR, !td_->contacts_manager_->have_user(sender_user_id)) << "Have no info about " << sender_user_id;
+  if (!td_->auth_manager_->is_bot()) {
+    LOG(ERROR) << "Receive new callback query";
+    return;
+  }
+  if (!message_id.is_valid()) {
+    LOG(ERROR) << "Receive new callback query from " << message_id << " in " << dialog_id << " sent by "
+               << sender_user_id;
+    return;
+  }
+
+  auto payload = get_query_payload(flags, std::move(data), std::move(game_short_name));
+  if (payload == nullptr) {
+    return;
+  }
+
+  td_->messages_manager_->force_create_dialog(dialog_id, "on_new_callback_query");
+  send_closure(
+      G()->td(), &Td::send_update,
+      make_tl_object<td_api::updateNewCallbackQuery>(
+          callback_query_id, td_->contacts_manager_->get_user_id_object(sender_user_id, "updateNewCallbackQuery"),
+          dialog_id.get(), message_id.get(), chat_instance, std::move(payload)));
+}
+
+void CallbackQueriesManager::on_new_inline_query(
+    int32 flags, int64 callback_query_id, UserId sender_user_id,
+    tl_object_ptr<telegram_api::inputBotInlineMessageID> &&inline_message_id, BufferSlice &&data, int64 chat_instance,
+    string &&game_short_name) {
+  if (!sender_user_id.is_valid()) {
+    LOG(ERROR) << "Receive new callback query from invalid " << sender_user_id;
+    return;
+  }
+  LOG_IF(ERROR, !td_->contacts_manager_->have_user(sender_user_id)) << "Have no info about " << sender_user_id;
+  if (!td_->auth_manager_->is_bot()) {
+    LOG(ERROR) << "Receive new callback query";
+    return;
+  }
+  CHECK(inline_message_id != nullptr);
+
+  auto payload = get_query_payload(flags, std::move(data), std::move(game_short_name));
+  if (payload == nullptr) {
+    return;
+  }
+  send_closure(
+      G()->td(), &Td::send_update,
+      make_tl_object<td_api::updateNewInlineCallbackQuery>(
+          callback_query_id, td_->contacts_manager_->get_user_id_object(sender_user_id, "updateNewInlineCallbackQuery"),
+          InlineQueriesManager::get_inline_message_id(std::move(inline_message_id)), chat_instance,
+          std::move(payload)));
+}
+
+int64 CallbackQueriesManager::send_callback_query(FullMessageId full_message_id,
+                                                  const tl_object_ptr<td_api::CallbackQueryPayload> &payload,
+                                                  Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    promise.set_error(Status::Error(5, "Bot can't send callback queries to other bot"));
+    return 0;
+  }
+
+  if (payload == nullptr) {
+    promise.set_error(Status::Error(5, "Payload should not be empty"));
+    return 0;
+  }
+
+  auto dialog_id = full_message_id.get_dialog_id();
+  if (!td_->messages_manager_->have_input_peer(dialog_id, AccessRights::Read)) {
+    promise.set_error(Status::Error(5, "Can't access the chat"));
+    return 0;
+  }
+
+  if (!td_->messages_manager_->have_message(full_message_id)) {
+    promise.set_error(Status::Error(5, "Message not found"));
+    return 0;
+  }
+  if (!full_message_id.get_message_id().is_server()) {
+    promise.set_error(Status::Error(5, "Bad message identifier"));
+    return 0;
+  }
+
+  int64 result_id;
+  do {
+    result_id = Random::secure_int64();
+  } while (callback_query_answers_.find(result_id) != callback_query_answers_.end());
+  callback_query_answers_[result_id];  // reserve place for result
+
+  td_->create_handler<GetBotCallbackAnswerQuery>(std::move(promise))
+      ->send(dialog_id, full_message_id.get_message_id(), payload, result_id);
+
+  return result_id;
+}
+
+void CallbackQueriesManager::on_get_callback_query_answer(
+    int64 result_id, tl_object_ptr<telegram_api::messages_botCallbackAnswer> &&answer) {
+  LOG(INFO) << "Receive answer for callback query " << result_id;
+  auto it = callback_query_answers_.find(result_id);
+  CHECK(it != callback_query_answers_.end());
+  CHECK(it->second.text.empty());
+  if (answer == nullptr) {
+    callback_query_answers_.erase(it);
+    return;
+  }
+
+  LOG(INFO) << to_string(answer);
+  it->second = CallbackQueryAnswer{(answer->flags_ & BOT_CALLBACK_ANSWER_FLAG_NEED_SHOW_ALERT) != 0, answer->message_,
+                                   answer->url_};
+}
+
+tl_object_ptr<td_api::callbackQueryAnswer> CallbackQueriesManager::get_callback_query_answer_object(int64 result_id) {
+  auto it = callback_query_answers_.find(result_id);
+  CHECK(it != callback_query_answers_.end());
+  bool show_alert = it->second.show_alert;
+  auto text = std::move(it->second.text);
+  auto url = std::move(it->second.url);
+  callback_query_answers_.erase(it);
+  return make_tl_object<td_api::callbackQueryAnswer>(text, show_alert, url);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/CallbackQueriesManager.h b/libs/tdlib/td/td/telegram/CallbackQueriesManager.h
new file mode 100644
index 0000000000..f2a0645088
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/CallbackQueriesManager.h
@@ -0,0 +1,68 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/DialogId.h"
+#include "td/telegram/MessageId.h"
+#include "td/telegram/UserId.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+
+#include <unordered_map>
+
+namespace td {
+
+class Td;
+
+template <class T>
+class Promise;
+
+class CallbackQueriesManager {
+ public:
+  explicit CallbackQueriesManager(Td *td);
+
+  void answer_callback_query(int64 callback_query_id, const string &text, bool show_alert, const string &url,
+                             int32 cache_time, Promise<Unit> &&promise) const;
+
+  void on_new_query(int32 flags, int64 callback_query_id, UserId sender_user_id, DialogId dialog_id,
+                    MessageId message_id, BufferSlice &&data, int64 chat_instance, string &&game_short_name);
+
+  void on_new_inline_query(int32 flags, int64 callback_query_id, UserId sender_user_id,
+                           tl_object_ptr<telegram_api::inputBotInlineMessageID> &&inline_message_id, BufferSlice &&data,
+                           int64 chat_instance, string &&game_short_name);
+
+  int64 send_callback_query(FullMessageId full_message_id, const tl_object_ptr<td_api::CallbackQueryPayload> &payload,
+                            Promise<Unit> &&promise);
+
+  void on_get_callback_query_answer(int64 result_id, tl_object_ptr<telegram_api::messages_botCallbackAnswer> &&answer);
+
+  tl_object_ptr<td_api::callbackQueryAnswer> get_callback_query_answer_object(int64 result_id);
+
+ private:
+  static constexpr int32 BOT_CALLBACK_ANSWER_FLAG_HAS_MESSAGE = 1 << 0;
+  static constexpr int32 BOT_CALLBACK_ANSWER_FLAG_NEED_SHOW_ALERT = 1 << 1;
+  static constexpr int32 BOT_CALLBACK_ANSWER_FLAG_HAS_URL = 1 << 2;
+
+  struct CallbackQueryAnswer {
+    bool show_alert;
+    string text;
+    string url;
+  };
+
+  tl_object_ptr<td_api::CallbackQueryPayload> get_query_payload(int32 flags, BufferSlice &&data,
+                                                                string &&game_short_name);
+
+  std::unordered_map<int64, CallbackQueryAnswer> callback_query_answers_;
+
+  Td *td_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/ChannelId.h b/libs/tdlib/td/td/telegram/ChannelId.h
new file mode 100644
index 0000000000..0924de59bc
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/ChannelId.h
@@ -0,0 +1,65 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/StringBuilder.h"
+
+#include <functional>
+#include <type_traits>
+
+namespace td {
+
+class ChannelId {
+  int32 id = 0;
+
+ public:
+  ChannelId() = default;
+
+  explicit ChannelId(int32 channel_id) : id(channel_id) {
+  }
+  template <class T, typename = std::enable_if_t<std::is_convertible<T, int32>::value>>
+  ChannelId(T channel_id) = delete;
+
+  bool is_valid() const {
+    return id > 0;  // TODO better is_valid
+  }
+
+  int32 get() const {
+    return id;
+  }
+
+  bool operator==(const ChannelId &other) const {
+    return id == other.id;
+  }
+
+  bool operator!=(const ChannelId &other) const {
+    return id != other.id;
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    storer.store_int(id);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    id = parser.fetch_int();
+  }
+};
+
+struct ChannelIdHash {
+  std::size_t operator()(ChannelId channel_id) const {
+    return std::hash<int32>()(channel_id.get());
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &string_builder, ChannelId channel_id) {
+  return string_builder << "supergroup " << channel_id.get();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/ChatId.h b/libs/tdlib/td/td/telegram/ChatId.h
new file mode 100644
index 0000000000..89b1483024
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/ChatId.h
@@ -0,0 +1,65 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/StringBuilder.h"
+
+#include <functional>
+#include <type_traits>
+
+namespace td {
+
+class ChatId {
+  int32 id = 0;
+
+ public:
+  ChatId() = default;
+
+  explicit ChatId(int32 chat_id) : id(chat_id) {
+  }
+  template <class T, typename = std::enable_if_t<std::is_convertible<T, int32>::value>>
+  ChatId(T chat_id) = delete;
+
+  bool is_valid() const {
+    return id > 0;
+  }
+
+  int32 get() const {
+    return id;
+  }
+
+  bool operator==(const ChatId &other) const {
+    return id == other.id;
+  }
+
+  bool operator!=(const ChatId &other) const {
+    return id != other.id;
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    storer.store_int(id);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    id = parser.fetch_int();
+  }
+};
+
+struct ChatIdHash {
+  std::size_t operator()(ChatId chat_id) const {
+    return std::hash<int32>()(chat_id.get());
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &string_builder, ChatId chat_id) {
+  return string_builder << "basic group " << chat_id.get();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Client.cpp b/libs/tdlib/td/td/telegram/Client.cpp
new file mode 100644
index 0000000000..d646932872
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Client.cpp
@@ -0,0 +1,291 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/Client.h"
+
+#include "td/telegram/Td.h"
+
+#include "td/utils/crypto.h"
+#include "td/utils/logging.h"
+#include "td/utils/MpscPollableQueue.h"
+#include "td/utils/Observer.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/Poll.h"
+#include "td/utils/port/thread.h"
+
+#include <deque>
+
+namespace td {
+
+#if TD_THREAD_UNSUPPORTED || TD_EVENTFD_UNSUPPORTED
+
+class Client::Impl final {
+ public:
+  Impl() {
+    init();
+  }
+
+  void send(Request request) {
+    if (request.id == 0 || request.function == nullptr) {
+      LOG(ERROR) << "Drop wrong request " << request.id;
+      return;
+    }
+
+    requests_.push_back(std::move(request));
+  }
+
+  Response receive(double timeout) {
+    if (!requests_.empty()) {
+      auto guard = scheduler_->get_current_guard();
+      for (auto &request : requests_) {
+        send_closure_later(td_, &Td::request, request.id, std::move(request.function));
+      }
+      requests_.clear();
+    }
+
+    if (responses_.empty()) {
+      scheduler_->run_main(0);
+    }
+    if (!responses_.empty()) {
+      auto result = std::move(responses_.front());
+      responses_.pop_front();
+      return result;
+    }
+    return {0, nullptr};
+  }
+
+  ~Impl() {
+    {
+      auto guard = scheduler_->get_current_guard();
+      td_.reset();
+    }
+    while (!closed_) {
+      scheduler_->run_main(0);
+    }
+    scheduler_.reset();
+  }
+
+ private:
+  std::deque<Response> responses_;
+  std::vector<Request> requests_;
+  int output_queue_ready_cnt_{0};
+  std::unique_ptr<ConcurrentScheduler> scheduler_;
+  ActorOwn<Td> td_;
+  bool closed_ = false;
+
+  void init() {
+    scheduler_ = std::make_unique<ConcurrentScheduler>();
+    scheduler_->init(0);
+    class Callback : public TdCallback {
+     public:
+      Callback(Impl *client) : client_(client) {
+      }
+      void on_result(std::uint64_t id, td_api::object_ptr<td_api::Object> result) override {
+        client_->responses_.push_back({id, std::move(result)});
+      }
+      void on_error(std::uint64_t id, td_api::object_ptr<td_api::error> error) override {
+        client_->responses_.push_back({id, std::move(error)});
+      }
+      void on_closed() override {
+        client_->closed_ = true;
+        Scheduler::instance()->yield();
+      }
+
+     private:
+      Impl *client_;
+    };
+    td_ = scheduler_->create_actor_unsafe<Td>(0, "Td", make_unique<Callback>(this));
+    scheduler_->start();
+  }
+};
+
+#else
+
+/*** TdProxy ***/
+using InputQueue = MpscPollableQueue<Client::Request>;
+using OutputQueue = MpscPollableQueue<Client::Response>;
+class TdProxy : public Actor {
+ public:
+  TdProxy(std::shared_ptr<InputQueue> input_queue, std::shared_ptr<OutputQueue> output_queue)
+      : input_queue_(std::move(input_queue)), output_queue_(std::move(output_queue)) {
+  }
+
+ private:
+  std::shared_ptr<InputQueue> input_queue_;
+  std::shared_ptr<OutputQueue> output_queue_;
+  bool is_td_closed_ = false;
+  bool was_hangup_ = false;
+  ActorOwn<Td> td_;
+
+  void start_up() override {
+    auto &fd = input_queue_->reader_get_event_fd();
+    fd.get_fd().set_observer(this);
+    ::td::subscribe(fd.get_fd(), Fd::Read);
+
+    class Callback : public TdCallback {
+     public:
+      Callback(ActorId<TdProxy> parent, std::shared_ptr<OutputQueue> output_queue)
+          : parent_(parent), output_queue_(std::move(output_queue)) {
+      }
+      void on_result(std::uint64_t id, td_api::object_ptr<td_api::Object> result) override {
+        output_queue_->writer_put({id, std::move(result)});
+      }
+      void on_error(std::uint64_t id, td_api::object_ptr<td_api::error> error) override {
+        output_queue_->writer_put({id, std::move(error)});
+      }
+      void on_closed() override {
+        send_closure(parent_, &TdProxy::on_closed);
+      }
+
+     private:
+      ActorId<TdProxy> parent_;
+      std::shared_ptr<OutputQueue> output_queue_;
+    };
+    td_ = create_actor<Td>("Td", make_unique<Callback>(actor_id(this), std::move(output_queue_)));
+    yield();
+  }
+
+  void on_closed() {
+    is_td_closed_ = true;
+    try_stop();
+  }
+
+  void try_stop() {
+    if (!is_td_closed_ || !was_hangup_) {
+      return;
+    }
+    Scheduler::instance()->finish();
+    stop();
+  }
+
+  void loop() override {
+    while (true) {
+      int size = input_queue_->reader_wait_nonblock();
+      if (size == 0) {
+        return;
+      }
+      for (int i = 0; i < size; i++) {
+        auto request = input_queue_->reader_get_unsafe();
+        if (request.id == 0 && request.function == nullptr) {
+          was_hangup_ = true;
+          td_.reset();
+          return try_stop();
+        }
+        send_closure_later(td_, &Td::request, request.id, std::move(request.function));
+      }
+    }
+  }
+
+  void hangup() override {
+    UNREACHABLE();
+  }
+
+  void tear_down() override {
+    auto &fd = input_queue_->reader_get_event_fd();
+    ::td::unsubscribe(fd.get_fd());
+    fd.get_fd().set_observer(nullptr);
+  }
+};
+
+/*** Client::Impl ***/
+class Client::Impl final : ObserverBase {
+ public:
+  Impl() {
+    init();
+  }
+
+  void send(Request request) {
+    if (request.id == 0 || request.function == nullptr) {
+      LOG(ERROR) << "Drop wrong request " << request.id;
+      return;
+    }
+
+    input_queue_->writer_put(std::move(request));
+  }
+
+  Response receive(double timeout) {
+    if (output_queue_ready_cnt_ == 0) {
+      output_queue_ready_cnt_ = output_queue_->reader_wait_nonblock();
+    }
+    if (output_queue_ready_cnt_ > 0) {
+      output_queue_ready_cnt_--;
+      return output_queue_->reader_get_unsafe();
+    }
+    if (timeout != 0) {
+      poll_.run(static_cast<int>(timeout * 1000));
+      return receive(0);
+    }
+    return {0, nullptr};
+  }
+
+  ~Impl() {
+    input_queue_->writer_put({0, nullptr});
+    scheduler_thread_.join();
+  }
+
+ private:
+  Poll poll_;
+  std::shared_ptr<InputQueue> input_queue_;
+  std::shared_ptr<OutputQueue> output_queue_;
+  std::shared_ptr<ConcurrentScheduler> scheduler_;
+  int output_queue_ready_cnt_{0};
+  thread scheduler_thread_;
+  bool notify_flag_{false};
+
+  void init() {
+    input_queue_ = std::make_shared<InputQueue>();
+    input_queue_->init();
+    output_queue_ = std::make_shared<OutputQueue>();
+    output_queue_->init();
+    scheduler_ = std::make_shared<ConcurrentScheduler>();
+    scheduler_->init(3);
+    scheduler_->create_actor_unsafe<TdProxy>(0, "TdProxy", input_queue_, output_queue_).release();
+    scheduler_->start();
+
+    scheduler_thread_ = thread([scheduler = scheduler_] {
+      while (scheduler->run_main(10)) {
+      }
+      scheduler->finish();
+    });
+
+    poll_.init();
+    auto &event_fd = output_queue_->reader_get_event_fd();
+    event_fd.get_fd().set_observer(this);
+    poll_.subscribe(event_fd.get_fd(), Fd::Read);
+  }
+
+  void notify() override {
+    notify_flag_ = true;
+  }
+};
+#endif
+
+/*** Client ***/
+Client::Client() : impl_(make_unique<Impl>()) {
+  // At least it should be enough for everybody who uses TDLib
+  init_openssl_threads();
+}
+
+void Client::send(Request &&request) {
+  impl_->send(std::move(request));
+}
+
+Client::Response Client::receive(double timeout) {
+  return impl_->receive(timeout);
+}
+
+Client::Response Client::execute(Request &&request) {
+  Response response;
+  response.id = request.id;
+  response.object = Td::static_request(std::move(request.function));
+  return response;
+}
+
+Client::~Client() = default;
+Client::Client(Client &&other) = default;
+Client &Client::operator=(Client &&other) = default;
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Client.h b/libs/tdlib/td/td/telegram/Client.h
new file mode 100644
index 0000000000..ccd891b009
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Client.h
@@ -0,0 +1,134 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+///\file
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/td_api.hpp"
+
+#include <cstdint>
+#include <memory>
+
+namespace td {
+
+/**
+ * Native C++ interface for interaction with TDLib.
+ *
+ * The TDLib instance is created for the lifetime of the Client object.
+ * Requests to TDLib can be sent using the Client::send method from any thread.
+ * New updates and responses to requests can be received using the Client::receive method from any thread,
+ * this function shouldn't be called simultaneously from two different threads. Also note that all updates and
+ * responses to requests should be applied in the same order as they were received, to ensure consistency.
+ * Given this information, it's advisable to call this function from a dedicated thread.
+ * Some service TDLib requests can be executed synchronously from any thread by using the Client::execute method.
+ *
+ * General pattern of usage:
+ * \code
+ * std::shared_ptr<td::Client> client = std::make_shared<td::Client>();
+ * // somehow share the client with other threads, which will be able to send requests via client->send
+ *
+ * const double WAIT_TIMEOUT = 10.0;  // seconds
+ * bool is_closed = false;            // should be set to true, when updateAuthorizationState with
+ *                                    // authorizationStateClosed is received
+ * while (!is_closed) {
+ *   auto response = client->receive(WAIT_TIMEOUT);
+ *   if (response.object == nullptr) {
+ *     continue;
+ *   }
+ *
+ *   if (response.id == 0) {
+ *     // process response.object as an incoming update of type td_api::Update
+ *   } else {
+ *     // process response.object as an answer to a sent request with id response.id
+ *   }
+ * }
+ * \endcode
+ */
+class Client final {
+ public:
+  /**
+   * Creates a new TDLib client.
+   */
+  Client();
+
+  /**
+   * A request to the TDLib.
+   */
+  struct Request {
+    /**
+     * Request identifier.
+     * Responses to TDLib requests will have the same id as the corresponding request.
+     * Updates from TDLib will have id == 0, incoming requests are thus disallowed to have id == 0.
+     */
+    std::uint64_t id;
+
+    /**
+     * TDLib API function representing a request to TDLib.
+     */
+    td_api::object_ptr<td_api::Function> function;
+  };
+
+  /**
+   * Sends request to TDLib. May be called from any thread.
+   * \param[in] request Request to TDLib.
+   */
+  void send(Request &&request);
+
+  /**
+   * A response to a request, or an incoming update from TDLib.
+   */
+  struct Response {
+    /**
+     * TDLib request identifier, which corresponds to the response or 0 for incoming updates from TDLib.
+     */
+    std::uint64_t id;
+
+    /**
+     * TDLib API object representing a response to a TDLib request or an incoming update.
+     */
+    td_api::object_ptr<td_api::Object> object;
+  };
+
+  /**
+   * Receives incoming updates and request responses from TDLib. May be called from any thread, but shouldn't be
+   * called simultaneously from two different threads.
+   * \param[in] timeout Maximum number of seconds allowed for this function to wait for new data.
+   * \return An incoming update or request response. The object returned in the response may be a nullptr
+   *         if the timeout expires.
+   */
+  Response receive(double timeout);
+
+  /**
+   * Synchronously executes TDLib requests. Only a few requests can be executed synchronously.
+   * May be called from any thread.
+   * \param[in] request Request to the TDLib.
+   * \return The request response.
+   */
+  static Response execute(Request &&request);
+
+  /**
+   * Destroys the client and TDLib instance.
+   */
+  ~Client();
+
+  /**
+   * Move constructor.
+   */
+  Client(Client &&other);
+
+  /**
+   * Move assignment operator.
+   */
+  Client &operator=(Client &&other);
+
+ private:
+  class Impl;
+  std::unique_ptr<Impl> impl_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/ClientActor.cpp b/libs/tdlib/td/td/telegram/ClientActor.cpp
new file mode 100644
index 0000000000..22652924a4
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/ClientActor.cpp
@@ -0,0 +1,37 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/ClientActor.h"
+
+#include "td/telegram/td_api.h"
+
+#include "td/telegram/net/NetQueryCounter.h"
+#include "td/telegram/Td.h"
+
+namespace td {
+ClientActor::ClientActor(unique_ptr<TdCallback> callback) {
+  td_ = create_actor<Td>("Td", std::move(callback));
+}
+
+void ClientActor::request(uint64 id, td_api::object_ptr<td_api::Function> request) {
+  send_closure(td_, &Td::request, id, std::move(request));
+}
+
+ClientActor::~ClientActor() = default;
+
+ClientActor::ClientActor(ClientActor &&other) = default;
+
+ClientActor &ClientActor::operator=(ClientActor &&other) = default;
+
+td_api::object_ptr<td_api::Object> ClientActor::execute(td_api::object_ptr<td_api::Function> request) {
+  return Td::static_request(std::move(request));
+}
+
+uint64 get_pending_network_query_count() {
+  return NetQueryCounter::get_count();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/ClientActor.h b/libs/tdlib/td/td/telegram/ClientActor.h
new file mode 100644
index 0000000000..37d6629b6d
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/ClientActor.h
@@ -0,0 +1,85 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+///\file
+
+#include "td/actor/actor.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/td_api.hpp"
+
+#include "td/telegram/TdCallback.h"
+
+#include "td/utils/common.h"
+
+namespace td {
+
+class Td;
+
+/**
+ * This is a low-level Actor interface for interaction with TDLib. The interface is a lot more flexible than
+ * the Client interface, however, for most usages the Client interface should be sufficient.
+ */
+class ClientActor : public Actor {
+ public:
+  /**
+   * Creates a ClientActor using the specified callback.
+   * \param[in] callback Callback for outgoing notifications from TDLib.
+   */
+  explicit ClientActor(unique_ptr<TdCallback> callback);
+
+  /**
+   * Sends one request to TDLib. The answer will be received via callback.
+   * \param[in] id Request identifier, must be positive.
+   * \param[in] request The request.
+   */
+  void request(uint64 id, td_api::object_ptr<td_api::Function> request);
+
+  /**
+   * Synchronously executes a TDLib request. Only a few requests can be executed synchronously.
+   * May be called from any thread.
+   * \param[in] request Request to the TDLib.
+   * \return The request response.
+   */
+  static td_api::object_ptr<td_api::Object> execute(td_api::object_ptr<td_api::Function> request);
+
+  /**
+   * Destroys the ClientActor and the TDLib instance.
+   */
+  ~ClientActor();
+
+  /**
+   * Move constructor.
+   */
+  ClientActor(ClientActor &&other);
+
+  /**
+   * Move assignment operator.
+   */
+  ClientActor &operator=(ClientActor &&other);
+
+  ClientActor(const ClientActor &other) = delete;
+  ClientActor &operator=(const ClientActor &other) = delete;
+
+ private:
+  ActorOwn<Td> td_;
+};
+
+/**
+ * Dumps information about all pending network queries to the internal TDLib log.
+ * This is useful for library debugging.
+ */
+void dump_pending_network_queries();
+
+/**
+ * Returns the current number of pending network queries. Useful for library debugging.
+ * \return Number of currently pending network queries.
+ */
+uint64 get_pending_network_query_count();
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/ClientDotNet.cpp b/libs/tdlib/td/td/telegram/ClientDotNet.cpp
new file mode 100644
index 0000000000..62ab095b0b
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/ClientDotNet.cpp
@@ -0,0 +1,137 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/Client.h"
+
+#include "td/telegram/TdDotNetApi.h"
+
+#include "td/utils/port/CxCli.h"
+
+#include <cstdint>
+
+namespace Telegram {
+namespace Td {
+
+using namespace CxCli;
+
+/// <summary>
+/// Interface for handler for results of queries to TDLib and incoming updates from TDLib.
+/// </summary>
+public interface class ClientResultHandler {
+  /// <summary>
+  /// Callback called on result of query to TDLib or incoming update from TDLib.
+  /// </summary>
+  /// <param name="object">Result of query or update of type Telegram.Td.Api.Update about new events.</param>
+  void OnResult(Api::BaseObject^ object);
+};
+
+/// <summary>
+/// Main class for interaction with the TDLib.
+/// </summary>
+public ref class Client sealed {
+public:
+  /// <summary>
+  /// Sends a request to the TDLib.
+  /// </summary>
+  /// <param name="function">Object representing a query to the TDLib.</param>
+  /// <param name="handler">Result handler with OnResult method which will be called with result
+  /// of the query or with Telegram.Td.Api.Error as parameter. If it is null, nothing will be called.</param>
+  /// <exception cref="NullReferenceException">Thrown when query is null.</exception>
+  void Send(Api::Function^ function, ClientResultHandler^ handler) {
+    if (function == nullptr) {
+      throw REF_NEW NullReferenceException("Function can't be null");
+    }
+
+    std::uint64_t queryId = Increment(currentId);
+    if (handler != nullptr) {
+      handlers[queryId] = handler;
+    }
+    td::Client::Request request;
+    request.id = queryId;
+    request.function = td::td_api::move_object_as<td::td_api::Function>(ToUnmanaged(function)->get_object_ptr());
+    client->send(std::move(request));
+  }
+
+  /// <summary>
+  /// Synchronously executes a TDLib request. Only a few marked accordingly requests can be executed synchronously.
+  /// </summary>
+  /// <param name="function">Object representing a query to the TDLib.</param>
+  /// <returns>Returns request result.</returns>
+  /// <exception cref="NullReferenceException">Thrown when query is null.</exception>
+  Api::BaseObject^ Execute(Api::Function^ function) {
+    if (function == nullptr) {
+      throw REF_NEW NullReferenceException("Function can't be null");
+    }
+
+    td::Client::Request request;
+    request.id = 0;
+    request.function = td::td_api::move_object_as<td::td_api::Function>(ToUnmanaged(function)->get_object_ptr());
+    return Api::FromUnmanaged(*client->execute(std::move(request)).object);
+  }
+
+  /// <summary>
+  /// Replaces handler for incoming updates from the TDLib.
+  /// </summary>
+  /// <param name="updatesHandler">Handler with OnResult method which will be called for every incoming update from the TDLib.</param>
+  void SetUpdatesHandler(ClientResultHandler^ updatesHandler) {
+    handlers[0] = updatesHandler;
+  }
+
+  /// <summary>
+  /// Launches a cycle which will fetch all results of queries to TDLib and incoming updates from TDLib.
+  /// Must be called once on a separate dedicated thread, on which all updates and query results will be handled.
+  /// Returns only when TDLib instance is closed.
+  /// </summary>
+  void Run() {
+    while (true) {
+      auto response = client->receive(10.0);
+      if (response.object != nullptr) {
+        ProcessResult(response.id, Api::FromUnmanaged(*response.object));
+
+        if (response.object->get_id() == td::td_api::updateAuthorizationState::ID &&
+            static_cast<td::td_api::updateAuthorizationState &>(*response.object).authorization_state_->get_id() ==
+            td::td_api::authorizationStateClosed::ID) {
+          break;
+        }
+      }
+    }
+  }
+
+  /// <summary>
+  /// Creates new Client.
+  /// </summary>
+  /// <param name="updatesHandler">Handler for incoming updates.</param>
+  /// <returns>Returns created Client.</returns>
+  static Client^ Create(ClientResultHandler^ updatesHandler) {
+    return REF_NEW Client(updatesHandler);
+  }
+
+private:
+  Client(ClientResultHandler^ updatesHandler) {
+    client = new td::Client();
+    handlers[0] = updatesHandler;
+  }
+
+  ~Client() {
+    delete client;
+  }
+
+  std::int64_t currentId = 0;
+  ConcurrentDictionary<std::uint64_t, ClientResultHandler^> handlers;
+  td::Client *client = nullptr;
+
+  void ProcessResult(std::uint64_t id, Api::BaseObject^ object) {
+    ClientResultHandler^ handler;
+    // update handler stays forever
+    if (id == 0 ? handlers.TryGetValue(id, handler) : handlers.TryRemove(id, handler)) {
+      // TODO try/catch
+      handler->OnResult(object);
+    }
+  }
+};
+
+}  // namespace Td
+}  // namespace Telegram
diff --git a/libs/tdlib/td/td/telegram/ClientJson.cpp b/libs/tdlib/td/td/telegram/ClientJson.cpp
new file mode 100644
index 0000000000..f5adc09eca
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/ClientJson.cpp
@@ -0,0 +1,97 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/ClientJson.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/td_api_json.h"
+
+#include "td/tl/tl_json.h"
+
+#include "td/utils/format.h"
+#include "td/utils/JsonBuilder.h"
+#include "td/utils/logging.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+Result<Client::Request> ClientJson::to_request(Slice request) {
+  auto request_str = request.str();
+  TRY_RESULT(json_value, json_decode(request_str));
+  if (json_value.type() != JsonValue::Type::Object) {
+    return Status::Error("Expected an object");
+  }
+  TRY_RESULT(extra_field, get_json_object_field(json_value.get_object(), "@extra", JsonValue::Type::Null, true));
+  std::uint64_t extra_id = extra_id_.fetch_add(1, std::memory_order_relaxed);
+  auto extra_str = json_encode<string>(extra_field);
+  if (!extra_str.empty()) {
+    std::lock_guard<std::mutex> guard(mutex_);
+    extra_[extra_id] = std::move(extra_str);
+  }
+
+  td_api::object_ptr<td_api::Function> func;
+  TRY_STATUS(from_json(func, json_value));
+  return Client::Request{extra_id, std::move(func)};
+}
+
+std::string ClientJson::from_response(Client::Response response) {
+  auto str = json_encode<string>(ToJson(static_cast<td_api::Object &>(*response.object)));
+  CHECK(!str.empty() && str.back() == '}');
+  std::string extra;
+  if (response.id != 0) {
+    std::lock_guard<std::mutex> guard(mutex_);
+    auto it = extra_.find(response.id);
+    if (it != extra_.end()) {
+      extra = std::move(it->second);
+      extra_.erase(it);
+    }
+  }
+  if (!extra.empty()) {
+    str.pop_back();
+    str.reserve(str.size() + 10 + extra.size());
+    str += ",\"@extra\":";
+    str += extra;
+    str += "}";
+  }
+  return str;
+}
+
+TD_THREAD_LOCAL std::string *ClientJson::current_output_;
+CSlice ClientJson::store_string(std::string str) {
+  init_thread_local<std::string>(ClientJson::current_output_);
+  *current_output_ = std::move(str);
+  return *current_output_;
+}
+
+void ClientJson::send(Slice request) {
+  auto status = [&] {
+    TRY_RESULT(client_request, to_request(request));
+    client_.send(std::move(client_request));
+    return Status::OK();
+  }();
+
+  LOG_IF(ERROR, status.is_error()) << "Failed to parse " << tag("request", format::escaped(request)) << " " << status;
+}
+
+CSlice ClientJson::receive(double timeout) {
+  auto response = client_.receive(timeout);
+  if (!response.object) {
+    return {};
+  }
+  return store_string(from_response(std::move(response)));
+}
+
+CSlice ClientJson::execute(Slice request) {
+  auto r_request = to_request(request);
+  if (r_request.is_error()) {
+    LOG(ERROR) << "Failed to parse " << tag("request", format::escaped(request)) << " " << r_request.error();
+    return {};
+  }
+
+  return store_string(from_response(Client::execute(r_request.move_as_ok())));
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/ClientJson.h b/libs/tdlib/td/td/telegram/ClientJson.h
new file mode 100644
index 0000000000..880f144d94
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/ClientJson.h
@@ -0,0 +1,44 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/Client.h"
+
+#include "td/utils/port/thread_local.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <atomic>
+#include <cstdint>
+#include <mutex>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+namespace td {
+
+class ClientJson final {
+ public:
+  void send(Slice request);
+
+  CSlice receive(double timeout);
+
+  CSlice execute(Slice request);
+
+ private:
+  Client client_;
+  std::mutex mutex_;  // for extra_
+  std::unordered_map<std::int64_t, std::string> extra_;
+  std::atomic<std::uint64_t> extra_id_{1};
+  static TD_THREAD_LOCAL std::string *current_output_;
+
+  CSlice store_string(std::string str);
+
+  Result<Client::Request> to_request(Slice request);
+  std::string from_response(Client::Response response);
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/ConfigManager.cpp b/libs/tdlib/td/td/telegram/ConfigManager.cpp
new file mode 100644
index 0000000000..c8a16d638e
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/ConfigManager.cpp
@@ -0,0 +1,751 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/ConfigManager.h"
+
+#include "td/telegram/ConfigShared.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/logevent/LogEvent.h"
+#include "td/telegram/net/ConnectionCreator.h"
+#include "td/telegram/net/DcOptions.h"
+#include "td/telegram/net/NetQuery.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+#include "td/telegram/net/Session.h"
+
+#if !TD_EMSCRIPTEN  //FIXME
+#include "td/net/HttpQuery.h"
+#include "td/net/SslFd.h"
+#include "td/net/Wget.h"
+#endif
+
+#include "td/actor/actor.h"
+
+#include "td/telegram/telegram_api.h"
+
+#include "td/utils/base64.h"
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/crypto.h"
+#include "td/utils/format.h"
+#include "td/utils/JsonBuilder.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/Clocks.h"
+#include "td/utils/Random.h"
+#include "td/utils/Time.h"
+#include "td/utils/tl_parsers.h"
+
+#include <algorithm>
+#include <memory>
+#include <utility>
+
+namespace td {
+
+static int VERBOSITY_NAME(config_recoverer) = VERBOSITY_NAME(INFO);
+
+Result<SimpleConfig> decode_config(Slice input) {
+  static auto rsa = td::RSA::from_pem(
+                        "-----BEGIN RSA PUBLIC KEY-----\n"
+                        "MIIBCgKCAQEAyr+18Rex2ohtVy8sroGP\n"
+                        "BwXD3DOoKCSpjDqYoXgCqB7ioln4eDCFfOBUlfXUEvM/fnKCpF46VkAftlb4VuPD\n"
+                        "eQSS/ZxZYEGqHaywlroVnXHIjgqoxiAd192xRGreuXIaUKmkwlM9JID9WS2jUsTp\n"
+                        "zQ91L8MEPLJ/4zrBwZua8W5fECwCCh2c9G5IzzBm+otMS/YKwmR1olzRCyEkyAEj\n"
+                        "XWqBI9Ftv5eG8m0VkBzOG655WIYdyV0HfDK/NWcvGqa0w/nriMD6mDjKOryamw0O\n"
+                        "P9QuYgMN0C9xMW9y8SmP4h92OAWodTYgY1hZCxdv6cs5UnW9+PWvS+WIbkh+GaWY\n"
+                        "xwIDAQAB\n"
+                        "-----END RSA PUBLIC KEY-----\n")
+                        .move_as_ok();
+
+  if (input.size() < 344 || input.size() > 1024) {
+    return Status::Error(PSLICE() << "Invalid " << tag("length", input.size()));
+  }
+
+  auto data_base64 = base64_filter(input);
+  if (data_base64.size() != 344) {
+    return Status::Error(PSLICE() << "Invalid " << tag("length", data_base64.size()) << " after base64_filter");
+  }
+  TRY_RESULT(data_rsa, base64_decode(data_base64));
+  if (data_rsa.size() != 256) {
+    return Status::Error(PSLICE() << "Invalid " << tag("length", data_rsa.size()) << " after base64_decode");
+  }
+
+  MutableSlice data_rsa_slice(data_rsa);
+  rsa.decrypt(data_rsa_slice, data_rsa_slice);
+
+  MutableSlice data_cbc = data_rsa_slice.substr(32);
+  UInt256 key;
+  UInt128 iv;
+  MutableSlice(key.raw, sizeof(key.raw)).copy_from(data_rsa_slice.substr(0, 32));
+  MutableSlice(iv.raw, sizeof(iv.raw)).copy_from(data_rsa_slice.substr(16, 16));
+  aes_cbc_decrypt(key, &iv, data_cbc, data_cbc);
+
+  CHECK(data_cbc.size() == 224);
+  string hash(32, ' ');
+  sha256(data_cbc.substr(0, 208), MutableSlice(hash));
+  if (data_cbc.substr(208) != Slice(hash).substr(0, 16)) {
+    return Status::Error("sha256 mismatch");
+  }
+
+  TlParser len_parser{data_cbc};
+  int len = len_parser.fetch_int();
+  if (len < 0 || len > 204) {
+    return Status::Error(PSLICE() << "Invalid " << tag("data length", len) << " after aes_cbc_decrypt");
+  }
+  int constructor_id = len_parser.fetch_int();
+  if (constructor_id != telegram_api::help_configSimple::ID) {
+    return Status::Error(PSLICE() << "Wrong " << tag("constructor", format::as_hex(constructor_id)));
+  }
+  BufferSlice raw_config(data_cbc.substr(8, len));
+  TlBufferParser parser{&raw_config};
+  auto config = telegram_api::help_configSimple::fetch(parser);
+  TRY_STATUS(parser.get_status());
+  return std::move(config);
+}
+
+static ActorOwn<> get_simple_config_impl(Promise<SimpleConfig> promise, int32 scheduler_id, string url, string host) {
+  VLOG(config_recoverer) << "Request simple config from " << url;
+#if TD_EMSCRIPTEN  // FIXME
+  return ActorOwn<>();
+#else
+  return ActorOwn<>(create_actor_on_scheduler<Wget>(
+      "Wget", scheduler_id,
+      PromiseCreator::lambda([promise = std::move(promise)](Result<HttpQueryPtr> r_query) mutable {
+        promise.set_result([&]() -> Result<SimpleConfig> {
+          TRY_RESULT(http_query, std::move(r_query));
+          return decode_config(http_query->content_);
+        }());
+      }),
+      std::move(url), std::vector<std::pair<string, string>>({{"Host", std::move(host)}}), 10 /*timeout*/, 3 /*ttl*/,
+      SslFd::VerifyPeer::Off));
+#endif
+}
+
+ActorOwn<> get_simple_config_azure(Promise<SimpleConfig> promise, bool is_test, int32 scheduler_id) {
+  string url = PSTRING() << "https://software-download.microsoft.com/" << (is_test ? "test" : "prod") << "/config.txt";
+  return get_simple_config_impl(std::move(promise), scheduler_id, std::move(url), "tcdnb.azureedge.net");
+}
+
+ActorOwn<> get_simple_config_google_app(Promise<SimpleConfig> promise, bool is_test, int32 scheduler_id) {
+  string url = PSTRING() << "https://www.google.com/" << (is_test ? "test/" : "");
+  return get_simple_config_impl(std::move(promise), scheduler_id, std::move(url), "dns-telegram.appspot.com");
+}
+
+ActorOwn<> get_simple_config_google_dns(Promise<SimpleConfig> promise, bool is_test, int32 scheduler_id) {
+  VLOG(config_recoverer) << "Request simple config from Google DNS";
+#if TD_EMSCRIPTEN  // FIXME
+  return ActorOwn<>();
+#else
+  return ActorOwn<>(create_actor_on_scheduler<Wget>(
+      "Wget", scheduler_id,
+      PromiseCreator::lambda([promise = std::move(promise)](Result<HttpQueryPtr> r_query) mutable {
+        promise.set_result([&]() -> Result<SimpleConfig> {
+          TRY_RESULT(http_query, std::move(r_query));
+          TRY_RESULT(json, json_decode(http_query->content_));
+          if (json.type() != JsonValue::Type::Object) {
+            return Status::Error("json error");
+          }
+          auto &answer_object = json.get_object();
+          TRY_RESULT(answer, get_json_object_field(answer_object, "Answer", JsonValue::Type::Array));
+          auto &answer_array = answer.get_array();
+          vector<string> parts;
+          for (auto &v : answer_array) {
+            if (v.type() != JsonValue::Type::Object) {
+              return Status::Error("json error");
+            }
+            auto &data_object = v.get_object();
+            TRY_RESULT(part, get_json_object_string_field(data_object, "data"));
+            parts.push_back(std::move(part));
+          }
+          if (parts.size() != 2) {
+            return Status::Error("Expected data in two parts");
+          }
+          string data;
+          if (parts[0].size() < parts[1].size()) {
+            data = parts[1] + parts[0];
+          } else {
+            data = parts[0] + parts[1];
+          }
+          return decode_config(data);
+        }());
+      }),
+      PSTRING() << "https://google.com/resolve?name=" << (is_test ? "t" : "") << "ap.stel.com&type=16",
+      std::vector<std::pair<string, string>>({{"Host", "dns.google.com"}}), 10 /*timeout*/, 3 /*ttl*/,
+      SslFd::VerifyPeer::Off));
+#endif
+}
+
+ActorOwn<> get_full_config(IPAddress ip_address, Promise<FullConfig> promise) {
+  class SessionCallback : public Session::Callback {
+   public:
+    SessionCallback(ActorShared<> parent, IPAddress address)
+        : parent_(std::move(parent)), address_(std::move(address)) {
+    }
+    void on_failed() final {
+    }
+    void on_closed() final {
+    }
+    void request_raw_connection(Promise<std::unique_ptr<mtproto::RawConnection>> promise) final {
+      request_raw_connection_cnt_++;
+      VLOG(config_recoverer) << "Request full config from " << address_ << ", try = " << request_raw_connection_cnt_;
+      if (request_raw_connection_cnt_ <= 1) {
+        send_closure(G()->connection_creator(), &ConnectionCreator::request_raw_connection_by_ip, address_,
+                     std::move(promise));
+      } else {
+        // Delay all queries except first forever
+        delay_forever_.push_back(std::move(promise));
+      }
+    }
+    void on_tmp_auth_key_updated(mtproto::AuthKey auth_key) final {
+      // nop
+    }
+
+   private:
+    ActorShared<> parent_;
+    IPAddress address_;
+    size_t request_raw_connection_cnt_{0};
+    std::vector<Promise<std::unique_ptr<mtproto::RawConnection>>> delay_forever_;
+  };
+
+  class SimpleAuthData : public AuthDataShared {
+   public:
+    DcId dc_id() const override {
+      return DcId::empty();
+    }
+    const std::shared_ptr<PublicRsaKeyShared> &public_rsa_key() override {
+      return public_rsa_key_;
+    }
+    mtproto::AuthKey get_auth_key() override {
+      return auth_key_;
+    }
+    std::pair<AuthState, bool> get_auth_state() override {
+      auto auth_key = get_auth_key();
+      AuthState state = AuthDataShared::get_auth_state(auth_key);
+      return std::make_pair(state, auth_key.was_auth_flag());
+    }
+    void set_auth_key(const mtproto::AuthKey &auth_key) override {
+      auth_key_ = auth_key;
+    }
+    void update_server_time_difference(double diff) override {
+      if (!has_server_time_difference_ || server_time_difference_ < diff) {
+        has_server_time_difference_ = true;
+        server_time_difference_ = diff;
+      }
+    }
+    double get_server_time_difference() override {
+      return server_time_difference_;
+    }
+    void add_auth_key_listener(unique_ptr<Listener> listener) override {
+      if (listener->notify()) {
+        auth_key_listeners_.push_back(std::move(listener));
+      }
+    }
+
+    void set_future_salts(const std::vector<mtproto::ServerSalt> &future_salts) override {
+      future_salts_ = future_salts;
+    }
+    std::vector<mtproto::ServerSalt> get_future_salts() override {
+      return future_salts_;
+    }
+
+   private:
+    std::shared_ptr<PublicRsaKeyShared> public_rsa_key_ = std::make_shared<PublicRsaKeyShared>(DcId::empty());
+    mtproto::AuthKey auth_key_;
+    bool has_server_time_difference_ = false;
+    double server_time_difference_ = 0;
+
+    std::vector<mtproto::ServerSalt> future_salts_;
+
+    std::vector<std::unique_ptr<Listener>> auth_key_listeners_;
+    void notify() {
+      auto it = std::remove_if(auth_key_listeners_.begin(), auth_key_listeners_.end(),
+                               [&](auto &listener) { return !listener->notify(); });
+      auth_key_listeners_.erase(it, auth_key_listeners_.end());
+    }
+  };
+
+  class GetConfigActor : public NetQueryCallback {
+   public:
+    GetConfigActor(IPAddress ip_address, Promise<FullConfig> promise)
+        : ip_address_(std::move(ip_address)), promise_(std::move(promise)) {
+    }
+
+   private:
+    void start_up() override {
+      auto session_callback = std::make_unique<SessionCallback>(actor_shared(this, 1), std::move(ip_address_));
+
+      auto auth_data = std::make_shared<SimpleAuthData>();
+      session_ = create_actor<Session>("ConfigSession", std::move(session_callback), std::move(auth_data),
+                                       false /*is_main*/, false /*use_pfs*/, true /*is_cdn*/, mtproto::AuthKey());
+      auto query = G()->net_query_creator().create(create_storer(telegram_api::help_getConfig()), DcId::empty(),
+                                                   NetQuery::Type::Common, NetQuery::AuthFlag::Off,
+                                                   NetQuery::GzipFlag::On, 60 * 60 * 24);
+      query->set_callback(actor_shared(this));
+      query->dispatch_ttl = 0;
+      send_closure(session_, &Session::send, std::move(query));
+      set_timeout_in(10);
+    }
+    void on_result(NetQueryPtr query) override {
+      promise_.set_result(fetch_result<telegram_api::help_getConfig>(std::move(query)));
+      stop();
+    }
+    void hangup_shared() override {
+      if (get_link_token() == 1) {
+        promise_.set_error(Status::Error("Failed"));
+        stop();
+      }
+    }
+    void hangup() override {
+      session_.reset();
+    }
+    void timeout_expired() override {
+      promise_.set_error(Status::Error("Timeout expired"));
+      stop();
+    }
+
+    IPAddress ip_address_;
+    ActorOwn<Session> session_;
+    Promise<FullConfig> promise_;
+  };
+
+  return ActorOwn<>(create_actor<GetConfigActor>("GetConfigActor", std::move(ip_address), std::move(promise)));
+}
+
+class ConfigRecoverer : public Actor {
+ public:
+  explicit ConfigRecoverer(ActorShared<> parent) : parent_(std::move(parent)) {
+  }
+
+  void on_dc_options_update(DcOptions dc_options) {
+    dc_options_update_ = dc_options;
+    update_dc_options();
+    loop();
+  }
+
+ private:
+  void on_network(bool has_network, uint32 network_generation) {
+    has_network_ = has_network;
+    if (network_generation_ != network_generation) {
+      if (has_network_) {
+        has_network_since_ = Time::now_cached();
+      }
+    }
+    loop();
+  }
+  void on_online(bool is_online) {
+    is_online_ = is_online;
+    loop();
+  }
+  void on_connecting(bool is_connecting) {
+    VLOG(config_recoverer) << "ON CONNECTING " << is_connecting;
+    if (is_connecting && !is_connecting_) {
+      connecting_since_ = Time::now_cached();
+    }
+    is_connecting_ = is_connecting;
+    loop();
+  }
+
+  void on_simple_config(Result<SimpleConfig> r_simple_config, bool dummy) {
+    simple_config_query_.reset();
+    auto r_dc_options = [&]() -> Result<DcOptions> {
+      if (r_simple_config.is_error()) {
+        return r_simple_config.move_as_error();
+      }
+      return DcOptions(*r_simple_config.ok());
+    }();
+    dc_options_i_ = 0;
+    if (r_dc_options.is_ok()) {
+      simple_config_ = r_dc_options.move_as_ok();
+      VLOG(config_recoverer) << "Got SimpleConfig " << simple_config_;
+      simple_config_expire_at_ = Time::now_cached() + Random::fast(20 * 60, 30 * 60);
+      simple_config_at_ = Time::now_cached();
+      for (size_t i = 1; i < simple_config_.dc_options.size(); i++) {
+        std::swap(simple_config_.dc_options[i], simple_config_.dc_options[Random::fast(0, static_cast<int>(i))]);
+      }
+    } else {
+      VLOG(config_recoverer) << "Get SimpleConfig error " << r_dc_options.error();
+      simple_config_ = DcOptions();
+      simple_config_expire_at_ = Time::now_cached() + Random::fast(15, 30);
+    }
+    update_dc_options();
+    loop();
+  }
+
+  void on_full_config(Result<FullConfig> r_full_config, bool dummy) {
+    full_config_query_.reset();
+    if (r_full_config.is_ok()) {
+      full_config_ = r_full_config.move_as_ok();
+      VLOG(config_recoverer) << "Got FullConfig " << to_string(full_config_);
+      full_config_expire_at_ = Time::now() + Random::fast(20 * 60, 30 * 60);
+      send_closure(G()->connection_creator(), &ConnectionCreator::on_dc_options, DcOptions(full_config_->dc_options_));
+    } else {
+      VLOG(config_recoverer) << "Get FullConfig error " << r_full_config.error();
+      full_config_ = FullConfig();
+      full_config_expire_at_ = Time::now() + Random::fast(15, 30);
+    }
+    loop();
+  }
+
+  bool is_connecting_{false};
+  double connecting_since_{0};
+
+  bool is_online_{false};
+
+  bool has_network_{false};
+  double has_network_since_{0};
+  uint32 network_generation_{0};
+
+  DcOptions simple_config_;
+  double simple_config_expire_at_{-1};
+  double simple_config_at_{0};
+  ActorOwn<> simple_config_query_;
+
+  DcOptions dc_options_update_;
+
+  DcOptions dc_options_;  // dc_options_update_ + simple_config_
+  double dc_options_at_{0};
+  size_t dc_options_i_;
+
+  FullConfig full_config_;
+  double full_config_expire_at_{0};
+  ActorOwn<> full_config_query_;
+
+  uint32 ref_cnt_{1};
+  bool close_flag_{false};
+  uint8 simple_config_turn_{0};
+
+  ActorShared<> parent_;
+
+  void hangup_shared() override {
+    ref_cnt_--;
+    try_stop();
+  }
+  void hangup() override {
+    ref_cnt_--;
+    close_flag_ = true;
+    full_config_query_.reset();
+    simple_config_query_.reset();
+    try_stop();
+  }
+
+  void try_stop() {
+    if (ref_cnt_ == 0) {
+      stop();
+    }
+  }
+
+  double max_connecting_delay() const {
+    return 20;
+  }
+  void loop() override {
+    if (close_flag_) {
+      return;
+    }
+
+    if (is_connecting_) {
+      VLOG(config_recoverer) << "Failed to connect for " << Time::now_cached() - connecting_since_;
+    } else {
+      VLOG(config_recoverer) << "Successfully connected";
+    }
+
+    Timestamp wakeup_timestamp;
+    auto check_timeout = [&](Timestamp timestamp) {
+      if (timestamp.at() < Time::now_cached()) {
+        return true;
+      }
+      wakeup_timestamp.relax(timestamp);
+      return false;
+    };
+
+    bool has_connecting_problem =
+        is_connecting_ && check_timeout(Timestamp::at(connecting_since_ + max_connecting_delay()));
+    bool is_valid_simple_config = !check_timeout(Timestamp::at(simple_config_expire_at_));
+    if (!is_valid_simple_config && !simple_config_.dc_options.empty()) {
+      simple_config_ = DcOptions();
+      update_dc_options();
+    }
+    bool need_simple_config = has_connecting_problem && !is_valid_simple_config && simple_config_query_.empty();
+    bool has_dc_options = !dc_options_.dc_options.empty();
+    bool is_valid_full_config = !check_timeout(Timestamp::at(full_config_expire_at_));
+    bool need_full_config = has_connecting_problem && has_dc_options && !is_valid_full_config &&
+                            full_config_query_.empty() && check_timeout(Timestamp::at(dc_options_at_ + 10));
+    if (need_simple_config) {
+      ref_cnt_++;
+      VLOG(config_recoverer) << "ASK SIMPLE CONFIG";
+      auto promise = PromiseCreator::lambda([actor_id = actor_shared(this)](Result<SimpleConfig> r_simple_config) {
+        send_closure(actor_id, &ConfigRecoverer::on_simple_config, std::move(r_simple_config), false);
+      });
+      auto get_dimple_config = [&]() {
+        switch (simple_config_turn_ % 3) {
+          case 0:
+            return get_simple_config_azure;
+          case 1:
+            return get_simple_config_google_app;
+          case 2:
+          default:
+            return get_simple_config_google_dns;
+        }
+      }();
+      simple_config_query_ = get_dimple_config(std::move(promise), G()->is_test_dc(), G()->get_gc_scheduler_id());
+      simple_config_turn_++;
+    }
+
+    if (need_full_config) {
+      ref_cnt_++;
+      VLOG(config_recoverer) << "ASK FULL CONFIG";
+      full_config_query_ =
+          get_full_config(dc_options_.dc_options[dc_options_i_].get_ip_address(),
+                          PromiseCreator::lambda([actor_id = actor_shared(this)](Result<FullConfig> r_full_config) {
+                            send_closure(actor_id, &ConfigRecoverer::on_full_config, std::move(r_full_config), false);
+                          }));
+      dc_options_i_ = (dc_options_i_ + 1) % dc_options_.dc_options.size();
+    }
+
+    if (wakeup_timestamp) {
+      VLOG(config_recoverer) << "Wakeup in " << format::as_time(wakeup_timestamp.in());
+      set_timeout_at(wakeup_timestamp.at());
+    } else {
+      VLOG(config_recoverer) << "Wakeup NEVER";
+    }
+  }
+
+  void start_up() override {
+    class StateCallback : public StateManager::Callback {
+     public:
+      explicit StateCallback(ActorId<ConfigRecoverer> parent) : parent_(std::move(parent)) {
+      }
+      bool on_state(StateManager::State state) override {
+        send_closure(parent_, &ConfigRecoverer::on_connecting, state == StateManager::State::Connecting);
+        return parent_.is_alive();
+      }
+      bool on_network(NetType network_type, uint32 network_generation) override {
+        send_closure(parent_, &ConfigRecoverer::on_network, network_type != NetType::None, network_generation);
+        return parent_.is_alive();
+      }
+      bool on_online(bool online_flag) override {
+        send_closure(parent_, &ConfigRecoverer::on_online, online_flag);
+        return parent_.is_alive();
+      }
+
+     private:
+      ActorId<ConfigRecoverer> parent_;
+    };
+    send_closure(G()->state_manager(), &StateManager::add_callback, make_unique<StateCallback>(actor_id(this)));
+  }
+
+  void update_dc_options() {
+    auto v = simple_config_.dc_options;
+    v.insert(v.begin(), dc_options_update_.dc_options.begin(), dc_options_update_.dc_options.end());
+    if (v != dc_options_.dc_options) {
+      dc_options_.dc_options = std::move(v);
+      dc_options_i_ = 0;
+      dc_options_at_ = Time::now();
+    }
+  }
+};
+
+ConfigManager::ConfigManager(ActorShared<> parent) : parent_(std::move(parent)) {
+}
+
+void ConfigManager::start_up() {
+  // TODO there are some problems when many ConfigRecoverers starts at the same time
+  // if (G()->parameters().use_file_db) {
+  ref_cnt_++;
+  config_recoverer_ = create_actor<ConfigRecoverer>("Recoverer", actor_shared());
+  send_closure(config_recoverer_, &ConfigRecoverer::on_dc_options_update, load_dc_options_update());
+  // }
+  auto expire = load_config_expire();
+  if (expire.is_in_past()) {
+    request_config();
+  } else {
+    expire_ = expire;
+    set_timeout_in(expire_.in());
+  }
+}
+
+void ConfigManager::hangup_shared() {
+  ref_cnt_--;
+  try_stop();
+}
+void ConfigManager::hangup() {
+  ref_cnt_--;
+  config_recoverer_.reset();
+  try_stop();
+}
+void ConfigManager::loop() {
+  if (expire_ && expire_.is_in_past()) {
+    request_config();
+    expire_ = {};
+  }
+}
+void ConfigManager::try_stop() {
+  if (ref_cnt_ == 0) {
+    stop();
+  }
+}
+void ConfigManager::request_config() {
+  if (config_sent_cnt_ != 0) {
+    return;
+  }
+  request_config_from_dc_impl(DcId::main());
+}
+
+void ConfigManager::on_dc_options_update(DcOptions dc_options) {
+  save_dc_options_update(dc_options);
+  send_closure(config_recoverer_, &ConfigRecoverer::on_dc_options_update, std::move(dc_options));
+  if (dc_options.dc_options.empty()) {
+    return;
+  }
+  expire_ = Timestamp::now();
+  save_config_expire(expire_);
+  set_timeout_in(expire_.in());
+}
+
+void ConfigManager::request_config_from_dc_impl(DcId dc_id) {
+  config_sent_cnt_++;
+  G()->net_query_dispatcher().dispatch_with_callback(
+      G()->net_query_creator().create(create_storer(telegram_api::help_getConfig()), dc_id, NetQuery::Type::Common,
+                                      NetQuery::AuthFlag::Off, NetQuery::GzipFlag::On, 60 * 60 * 24),
+      actor_shared(this));
+}
+
+void ConfigManager::on_result(NetQueryPtr res) {
+  CHECK(config_sent_cnt_ > 0);
+  config_sent_cnt_--;
+  auto r_config = fetch_result<telegram_api::help_getConfig>(std::move(res));
+  if (r_config.is_error()) {
+    LOG(ERROR) << "TODO: getConfig failed: " << r_config.error();
+    expire_ = Timestamp::in(60.0);  // try again in a minute
+    set_timeout_in(expire_.in());
+  } else {
+    on_dc_options_update(DcOptions());
+    process_config(r_config.move_as_ok());
+  }
+}
+
+void ConfigManager::save_dc_options_update(DcOptions dc_options) {
+  if (dc_options.dc_options.empty()) {
+    G()->td_db()->get_binlog_pmc()->erase("dc_options_update");
+    return;
+  }
+  G()->td_db()->get_binlog_pmc()->set("dc_options_update", log_event_store(dc_options).as_slice().str());
+}
+
+DcOptions ConfigManager::load_dc_options_update() {
+  auto log_event_dc_options = G()->td_db()->get_binlog_pmc()->get("dc_options_update");
+  DcOptions dc_options;
+  if (!log_event_dc_options.empty()) {
+    log_event_parse(dc_options, log_event_dc_options).ensure();
+  }
+  return dc_options;
+}
+
+Timestamp ConfigManager::load_config_expire() {
+  auto expire_in = to_integer<int32>(G()->td_db()->get_binlog_pmc()->get("config_expire")) - Clocks::system();
+
+  if (expire_in < 0 || expire_in > 60 * 60 /* 1 hour */) {
+    return Timestamp::now();
+  } else {
+    return Timestamp::in(expire_in);
+  }
+}
+
+void ConfigManager::save_config_expire(Timestamp timestamp) {
+  G()->td_db()->get_binlog_pmc()->set("config_expire", to_string(static_cast<int>(Clocks::system() + expire_.in())));
+}
+
+void ConfigManager::process_config(tl_object_ptr<telegram_api::config> config) {
+  bool is_from_main_dc = G()->net_query_dispatcher().main_dc_id().get_value() == config->this_dc_;
+
+  LOG(INFO) << to_string(config);
+  auto reload_in = max(60 /* at least 60 seconds*/, config->expires_ - config->date_);
+  save_config_expire(Timestamp::in(reload_in));
+  reload_in -= Random::fast(0, reload_in / 5);
+  if (!is_from_main_dc) {
+    reload_in = 0;
+  }
+  expire_ = Timestamp::in(reload_in);
+  set_timeout_at(expire_.at());
+  LOG_IF(ERROR, config->test_mode_ != G()->is_test_dc()) << "Wrong parameter is_test";
+
+  ConfigShared &shared_config = G()->shared_config();
+
+  // Do not save dc_options in config, because it will be interpreted and saved by ConnectionCreator.
+  send_closure(G()->connection_creator(), &ConnectionCreator::on_dc_options, DcOptions(config->dc_options_));
+
+  shared_config.set_option_integer("recent_stickers_limit", config->stickers_recent_limit_);
+  shared_config.set_option_integer("favorite_stickers_limit", config->stickers_faved_limit_);
+  shared_config.set_option_integer("saved_animations_limit", config->saved_gifs_limit_);
+  shared_config.set_option_integer("channels_read_media_period", config->channels_read_media_period_);
+
+  shared_config.set_option_boolean("test_mode", config->test_mode_);
+  shared_config.set_option_integer("forwarded_message_count_max", config->forwarded_count_max_);
+  shared_config.set_option_integer("basic_group_size_max", config->chat_size_max_);
+  shared_config.set_option_integer("supergroup_size_max", config->megagroup_size_max_);
+  shared_config.set_option_integer("pinned_chat_count_max", config->pinned_dialogs_count_max_);
+  if (is_from_main_dc || !shared_config.have_option("t_me_url")) {
+    shared_config.set_option_string("t_me_url", config->me_url_prefix_);
+  }
+  if (is_from_main_dc) {
+    if ((config->flags_ & telegram_api::config::TMP_SESSIONS_MASK) != 0) {
+      G()->shared_config().set_option_integer("session_count", config->tmp_sessions_);
+    } else {
+      G()->shared_config().set_option_empty("session_count");
+    }
+  }
+
+  if (is_from_main_dc) {
+    shared_config.set_option_integer("edit_time_limit", config->edit_time_limit_);
+    shared_config.set_option_boolean("revoke_pm_inbox",
+                                     (config->flags_ & telegram_api::config::REVOKE_PM_INBOX_MASK) != 0);
+    shared_config.set_option_integer("revoke_time_limit", config->revoke_time_limit_);
+    shared_config.set_option_integer("revoke_pm_time_limit", config->revoke_pm_time_limit_);
+
+    shared_config.set_option_integer("rating_e_decay", config->rating_e_decay_);
+
+    shared_config.set_option_boolean("calls_enabled", config->phonecalls_enabled_);
+  }
+  shared_config.set_option_integer("call_ring_timeout_ms", config->call_ring_timeout_ms_);
+  shared_config.set_option_integer("call_connect_timeout_ms", config->call_connect_timeout_ms_);
+  shared_config.set_option_integer("call_packet_timeout_ms", config->call_packet_timeout_ms_);
+  shared_config.set_option_integer("call_receive_timeout_ms", config->call_receive_timeout_ms_);
+
+  // delete outdated options
+  shared_config.set_option_empty("chat_big_size");
+  shared_config.set_option_empty("group_size_max");
+  shared_config.set_option_empty("saved_gifs_limit");
+  shared_config.set_option_empty("sessions_count");
+  shared_config.set_option_empty("forwarded_messages_count_max");
+  shared_config.set_option_empty("broadcast_size_max");
+  shared_config.set_option_empty("group_chat_size_max");
+  shared_config.set_option_empty("chat_size_max");
+  shared_config.set_option_empty("megagroup_size_max");
+  shared_config.set_option_empty("online_update_period_ms");
+  shared_config.set_option_empty("offline_blur_timeout_ms");
+  shared_config.set_option_empty("offline_idle_timeout_ms");
+  shared_config.set_option_empty("online_cloud_timeout_ms");
+  shared_config.set_option_empty("notify_cloud_delay_ms");
+  shared_config.set_option_empty("notify_default_delay_ms");
+  shared_config.set_option_empty("large_chat_size");
+
+  if (is_from_main_dc) {
+    for (auto &feature : shared_config.get_options("disabled_")) {
+      shared_config.set_option_empty(feature.first);
+    }
+  }
+
+  // TODO implement online status updates
+  //  shared_config.set_option_integer("online_update_period_ms", config->online_update_period_ms_);
+  //  shared_config.set_option_integer("offline_blur_timeout_ms", config->offline_blur_timeout_ms_);
+  //  shared_config.set_option_integer("offline_idle_timeout_ms", config->offline_idle_timeout_ms_);
+  //  shared_config.set_option_integer("online_cloud_timeout_ms", config->online_cloud_timeout_ms_);
+  //  shared_config.set_option_integer("notify_cloud_delay_ms", config->notify_cloud_delay_ms_);
+  //  shared_config.set_option_integer("notify_default_delay_ms", config->notify_default_delay_ms_);
+
+  //  shared_config.set_option_integer("push_chat_period_ms", config->push_chat_period_ms_);
+  //  shared_config.set_option_integer("push_chat_limit", config->push_chat_limit_);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/ConfigManager.h b/libs/tdlib/td/td/telegram/ConfigManager.h
new file mode 100644
index 0000000000..3f2c7f05cf
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/ConfigManager.h
@@ -0,0 +1,69 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/net/DcOptions.h"
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/actor.h"
+
+#include "td/utils/port/IPAddress.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/Time.h"
+
+namespace td {
+
+using SimpleConfig = tl_object_ptr<telegram_api::help_configSimple>;
+
+Result<SimpleConfig> decode_config(Slice input);
+
+ActorOwn<> get_simple_config_azure(Promise<SimpleConfig> promise, bool is_test = false, int32 scheduler_id = -1);
+
+ActorOwn<> get_simple_config_google_app(Promise<SimpleConfig> promise, bool is_test = false, int32 scheduler_id = -1);
+
+ActorOwn<> get_simple_config_google_dns(Promise<SimpleConfig> promise, bool is_test = false, int32 scheduler_id = -1);
+
+using FullConfig = tl_object_ptr<telegram_api::config>;
+
+ActorOwn<> get_full_config(IPAddress ip_address, Promise<FullConfig> promise);
+
+class ConfigRecoverer;
+class ConfigManager : public NetQueryCallback {
+ public:
+  explicit ConfigManager(ActorShared<> parent);
+
+  void request_config();
+
+  void on_dc_options_update(DcOptions dc_options);
+
+ private:
+  ActorShared<> parent_;
+  int32 config_sent_cnt_{0};
+  ActorOwn<ConfigRecoverer> config_recoverer_;
+  int ref_cnt_{1};
+  Timestamp expire_;
+
+  void start_up() override;
+  void hangup_shared() override;
+  void hangup() override;
+  void loop() override;
+  void try_stop();
+
+  void on_result(NetQueryPtr res) override;
+
+  void request_config_from_dc_impl(DcId dc_id);
+  void process_config(tl_object_ptr<telegram_api::config> config);
+
+  Timestamp load_config_expire();
+  void save_config_expire(Timestamp timestamp);
+  void save_dc_options_update(DcOptions dc_options);
+  DcOptions load_dc_options_update();
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/ConfigShared.cpp b/libs/tdlib/td/td/telegram/ConfigShared.cpp
new file mode 100644
index 0000000000..637d9fcdbc
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/ConfigShared.cpp
@@ -0,0 +1,126 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/ConfigShared.h"
+
+#include "td/telegram/td_api.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+
+namespace td {
+ConfigShared::ConfigShared(BinlogPmcPtr config_pmc, unique_ptr<Callback> callback)
+    : config_pmc_(config_pmc), callback_(std::move(callback)) {
+  for (auto key_value : config_pmc_->get_all()) {
+    on_option_updated(key_value.first);
+  }
+}
+void ConfigShared::set_option_boolean(Slice name, bool value) {
+  if (set_option(name, value ? Slice("Btrue") : Slice("Bfalse"))) {
+    on_option_updated(name);
+  }
+}
+
+void ConfigShared::set_option_empty(Slice name) {
+  if (set_option(name, Slice())) {
+    on_option_updated(name);
+  }
+}
+
+void ConfigShared::set_option_integer(Slice name, int32 value) {
+  if (set_option(name, PSLICE() << "I" << value)) {
+    on_option_updated(name);
+  }
+}
+
+void ConfigShared::set_option_string(Slice name, Slice value) {
+  if (set_option(name, PSLICE() << "S" << value)) {
+    on_option_updated(name);
+  }
+}
+
+bool ConfigShared::have_option(Slice name) const {
+  return config_pmc_->isset(name.str());
+}
+
+string ConfigShared::get_option(Slice name) const {
+  return config_pmc_->get(name.str());
+}
+
+std::unordered_map<string, string> ConfigShared::get_options(Slice prefix) const {
+  return config_pmc_->prefix_get(prefix);
+}
+
+std::unordered_map<string, string> ConfigShared::get_options() const {
+  return config_pmc_->get_all();
+}
+
+bool ConfigShared::get_option_boolean(Slice name) const {
+  auto value = get_option(name);
+  if (value.empty()) {
+    return false;
+  }
+  if (value == "Btrue") {
+    return true;
+  }
+  if (value == "Bfalse") {
+    return false;
+  }
+  LOG(ERROR) << "Found \"" << value << "\" instead of boolean option";
+  return false;
+}
+
+int32 ConfigShared::get_option_integer(Slice name, int32 default_value) const {
+  auto str_value = get_option(name);
+  if (str_value.empty()) {
+    return default_value;
+  }
+  if (str_value[0] != 'I') {
+    LOG(ERROR) << "Found \"" << str_value << "\" instead of integer option";
+    return default_value;
+  }
+  return to_integer<int32>(str_value.substr(1));
+}
+
+tl_object_ptr<td_api::OptionValue> ConfigShared::get_option_value(Slice value) const {
+  return get_option_value_object(get_option(value));
+}
+
+bool ConfigShared::set_option(Slice name, Slice value) {
+  if (value.empty()) {
+    return config_pmc_->erase(name.str()) != 0;
+  } else {
+    return config_pmc_->set(name.str(), value.str()) != 0;
+  }
+}
+
+tl_object_ptr<td_api::OptionValue> ConfigShared::get_option_value_object(Slice value) {
+  if (value.empty()) {
+    return make_tl_object<td_api::optionValueEmpty>();
+  }
+
+  switch (value[0]) {
+    case 'B':
+      if (value == "Btrue") {
+        return make_tl_object<td_api::optionValueBoolean>(true);
+      }
+      if (value == "Bfalse") {
+        return make_tl_object<td_api::optionValueBoolean>(false);
+      }
+      break;
+    case 'I':
+      return make_tl_object<td_api::optionValueInteger>(to_integer<int32>(value.substr(1)));
+    case 'S':
+      return make_tl_object<td_api::optionValueString>(value.substr(1).str());
+  }
+
+  return make_tl_object<td_api::optionValueString>(value.str());
+}
+
+void ConfigShared::on_option_updated(Slice name) {
+  callback_->on_option_updated(name.str());
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/ConfigShared.h b/libs/tdlib/td/td/telegram/ConfigShared.h
new file mode 100644
index 0000000000..03f3ca2807
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/ConfigShared.h
@@ -0,0 +1,56 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/db/Pmc.h"
+
+#include "td/telegram/td_api.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+
+#include <unordered_map>
+
+namespace td {
+class ConfigShared {
+ public:
+  class Callback {
+   public:
+    Callback() = default;
+    Callback(const Callback &) = delete;
+    Callback &operator=(const Callback &) = delete;
+    virtual ~Callback() = default;
+    virtual void on_option_updated(const string &name) = 0;
+  };
+
+  ConfigShared(BinlogPmcPtr config_pmc, unique_ptr<Callback> callback);
+
+  void set_option_boolean(Slice name, bool value);
+  void set_option_empty(Slice name);
+  void set_option_integer(Slice name, int32 value);
+  void set_option_string(Slice name, Slice value);
+
+  bool have_option(Slice name) const;
+  string get_option(Slice name) const;
+  std::unordered_map<string, string> get_options(Slice prefix) const;
+  std::unordered_map<string, string> get_options() const;
+
+  bool get_option_boolean(Slice name) const;
+  int32 get_option_integer(Slice name, int32 default_value = 0) const;
+
+  tl_object_ptr<td_api::OptionValue> get_option_value(Slice value) const;
+
+ private:
+  BinlogPmcPtr config_pmc_;
+  unique_ptr<Callback> callback_;
+
+  bool set_option(Slice name, Slice value);
+  static tl_object_ptr<td_api::OptionValue> get_option_value_object(Slice value);
+
+  void on_option_updated(Slice name);
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Contact.cpp b/libs/tdlib/td/td/telegram/Contact.cpp
new file mode 100644
index 0000000000..dd50281554
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Contact.cpp
@@ -0,0 +1,79 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/Contact.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/utils/common.h"
+
+#include <tuple>
+
+namespace td {
+
+Contact::Contact(string phone_number, string first_name, string last_name, int32 user_id)
+    : phone_number_(std::move(phone_number))
+    , first_name_(std::move(first_name))
+    , last_name_(std::move(last_name))
+    , user_id_(user_id) {
+  if (!user_id_.is_valid()) {
+    user_id_ = UserId();
+  }
+}
+
+void Contact::set_user_id(UserId user_id) {
+  user_id_ = user_id;
+}
+
+UserId Contact::get_user_id() const {
+  return user_id_;
+}
+
+string Contact::get_phone_number() const {
+  return phone_number_;
+}
+
+tl_object_ptr<td_api::contact> Contact::get_contact_object() const {
+  return make_tl_object<td_api::contact>(phone_number_, first_name_, last_name_, user_id_.get());
+}
+
+tl_object_ptr<telegram_api::inputMediaContact> Contact::get_input_media_contact() const {
+  return make_tl_object<telegram_api::inputMediaContact>(phone_number_, first_name_, last_name_);
+}
+
+SecretInputMedia Contact::get_secret_input_media_contact() const {
+  return SecretInputMedia{nullptr, make_tl_object<secret_api::decryptedMessageMediaContact>(
+                                       phone_number_, first_name_, last_name_, user_id_.get())};
+}
+
+tl_object_ptr<telegram_api::inputPhoneContact> Contact::get_input_phone_contact(int64 client_id) const {
+  return make_tl_object<telegram_api::inputPhoneContact>(client_id, phone_number_, first_name_, last_name_);
+}
+
+tl_object_ptr<telegram_api::inputBotInlineMessageMediaContact> Contact::get_input_bot_inline_message_media_contact(
+    int32 flags, tl_object_ptr<telegram_api::ReplyMarkup> &&reply_markup) const {
+  return make_tl_object<telegram_api::inputBotInlineMessageMediaContact>(flags, phone_number_, first_name_, last_name_,
+                                                                         std::move(reply_markup));
+}
+
+bool operator==(const Contact &lhs, const Contact &rhs) {
+  return std::tie(lhs.phone_number_, lhs.first_name_, lhs.last_name_, lhs.user_id_) ==
+         std::tie(rhs.phone_number_, rhs.first_name_, rhs.last_name_, rhs.user_id_);
+}
+
+bool operator!=(const Contact &lhs, const Contact &rhs) {
+  return !(lhs == rhs);
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const Contact &contact) {
+  return string_builder << "Contact[phone_number = " << contact.phone_number_
+                        << ", first_name = " << contact.first_name_ << ", last_name = " << contact.last_name_ << ", "
+                        << contact.user_id_ << "]";
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Contact.h b/libs/tdlib/td/td/telegram/Contact.h
new file mode 100644
index 0000000000..98254cebd6
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Contact.h
@@ -0,0 +1,101 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/SecretInputMedia.h"
+#include "td/telegram/UserId.h"
+
+#include "td/utils/common.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tl_helpers.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include <functional>
+#include <tuple>
+
+namespace td {
+
+class Contact {
+  string phone_number_;
+  string first_name_;
+  string last_name_;
+  UserId user_id_;
+
+  friend bool operator==(const Contact &lhs, const Contact &rhs);
+  friend bool operator!=(const Contact &lhs, const Contact &rhs);
+
+  friend StringBuilder &operator<<(StringBuilder &string_builder, const Contact &contact);
+
+  friend struct ContactEqual;
+  friend struct ContactHash;
+
+ public:
+  Contact() = default;
+
+  Contact(string phone_number, string first_name, string last_name, int32 user_id);
+
+  void set_user_id(UserId user_id);
+
+  UserId get_user_id() const;
+
+  string get_phone_number() const;
+
+  tl_object_ptr<td_api::contact> get_contact_object() const;
+
+  tl_object_ptr<telegram_api::inputMediaContact> get_input_media_contact() const;
+
+  SecretInputMedia get_secret_input_media_contact() const;
+
+  tl_object_ptr<telegram_api::inputPhoneContact> get_input_phone_contact(int64 client_id) const;
+
+  // TODO very strange function
+  tl_object_ptr<telegram_api::inputBotInlineMessageMediaContact> get_input_bot_inline_message_media_contact(
+      int32 flags, tl_object_ptr<telegram_api::ReplyMarkup> &&reply_markup) const;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    using td::store;
+    store(phone_number_, storer);
+    store(first_name_, storer);
+    store(last_name_, storer);
+    store(user_id_, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    using td::parse;
+    parse(phone_number_, parser);
+    parse(first_name_, parser);
+    parse(last_name_, parser);
+    parse(user_id_, parser);
+  }
+};
+
+bool operator==(const Contact &lhs, const Contact &rhs);
+bool operator!=(const Contact &lhs, const Contact &rhs);
+
+StringBuilder &operator<<(StringBuilder &string_builder, const Contact &contact);
+
+struct ContactEqual {
+  std::size_t operator()(const Contact &lhs, const Contact &rhs) const {
+    return std::tie(lhs.phone_number_, lhs.first_name_, lhs.last_name_) ==
+           std::tie(rhs.phone_number_, rhs.first_name_, rhs.last_name_);
+  }
+};
+
+struct ContactHash {
+  std::size_t operator()(const Contact &contact) const {
+    return (std::hash<std::string>()(contact.phone_number_) * 2023654985u +
+            std::hash<std::string>()(contact.first_name_)) *
+               2023654985u +
+           std::hash<std::string>()(contact.last_name_);
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/ContactsManager.cpp b/libs/tdlib/td/td/telegram/ContactsManager.cpp
new file mode 100644
index 0000000000..44faa4096d
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/ContactsManager.cpp
@@ -0,0 +1,9658 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/ContactsManager.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+#include "td/telegram/telegram_api.hpp"
+
+#include "td/actor/PromiseFuture.h"
+#include "td/actor/SleepActor.h"
+
+#include "td/db/binlog/BinlogHelper.h"
+
+#include "td/telegram/AuthManager.h"
+#include "td/telegram/ConfigShared.h"
+#include "td/telegram/files/FileManager.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/InlineQueriesManager.h"
+#include "td/telegram/logevent/LogEvent.h"
+#include "td/telegram/MessagesManager.h"
+#include "td/telegram/misc.h"
+#include "td/telegram/net/NetQuery.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/Photo.hpp"
+#include "td/telegram/SecretChatActor.h"
+#include "td/telegram/StickersManager.h"
+#include "td/telegram/Td.h"
+#include "td/telegram/TopDialogManager.h"
+#include "td/telegram/UpdatesManager.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Random.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/Time.h"
+#include "td/utils/tl_helpers.h"
+
+#include <algorithm>
+#include <limits>
+#include <tuple>
+#include <utility>
+
+namespace td {
+
+class SetAccountTtlQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit SetAccountTtlQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int32 account_ttl) {
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::account_setAccountTTL(make_tl_object<telegram_api::accountDaysTTL>(account_ttl)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::account_setAccountTTL>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.move_as_ok();
+    if (!result) {
+      return on_error(id, Status::Error(500, "Internal Server Error"));
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetAccountTtlQuery : public Td::ResultHandler {
+  Promise<int32> promise_;
+
+ public:
+  explicit GetAccountTtlQuery(Promise<int32> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::account_getAccountTTL())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::account_getAccountTTL>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for GetAccountTtlQuery: " << to_string(ptr);
+
+    promise_.set_value(std::move(ptr->days_));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetAuthorizationsQuery : public Td::ResultHandler {
+  Promise<tl_object_ptr<td_api::sessions>> promise_;
+  static constexpr int32 AUTHORIZATION_FLAG_IS_CURRENT = 1 << 0;
+  static constexpr int32 AUTHORIZATION_FLAG_IS_OFFICIAL_APPLICATION = 1 << 1;
+
+ public:
+  explicit GetAuthorizationsQuery(Promise<tl_object_ptr<td_api::sessions>> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::account_getAuthorizations())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::account_getAuthorizations>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for GetAuthorizationsQuery: " << to_string(ptr);
+
+    auto results = make_tl_object<td_api::sessions>();
+    results->sessions_.reserve(ptr->authorizations_.size());
+    for (auto &authorization : ptr->authorizations_) {
+      CHECK(authorization != nullptr);
+      bool is_current = (authorization->flags_ & AUTHORIZATION_FLAG_IS_CURRENT) != 0;
+      bool is_official_application = (authorization->flags_ & AUTHORIZATION_FLAG_IS_OFFICIAL_APPLICATION) != 0;
+
+      results->sessions_.push_back(make_tl_object<td_api::session>(
+          authorization->hash_, is_current, authorization->api_id_, authorization->app_name_,
+          authorization->app_version_, is_official_application, authorization->device_model_, authorization->platform_,
+          authorization->system_version_, authorization->date_created_, authorization->date_active_, authorization->ip_,
+          authorization->country_, authorization->region_));
+    }
+
+    promise_.set_value(std::move(results));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ResetAuthorizationQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit ResetAuthorizationQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int64 authorization_id) {
+    send_query(
+        G()->net_query_creator().create(create_storer(telegram_api::account_resetAuthorization(authorization_id))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::account_resetAuthorization>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.move_as_ok();
+    LOG_IF(WARNING, !result) << "Failed to terminate session";
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ResetAuthorizationsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit ResetAuthorizationsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::auth_resetAuthorizations())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::auth_resetAuthorizations>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.move_as_ok();
+    LOG_IF(WARNING, !result) << "Failed to terminate all sessions";
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetWebAuthorizationsQuery : public Td::ResultHandler {
+  Promise<tl_object_ptr<td_api::connectedWebsites>> promise_;
+
+ public:
+  explicit GetWebAuthorizationsQuery(Promise<tl_object_ptr<td_api::connectedWebsites>> &&promise)
+      : promise_(std::move(promise)) {
+  }
+
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::account_getWebAuthorizations())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::account_getWebAuthorizations>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for GetWebAuthorizationsQuery: " << to_string(ptr);
+
+    td->contacts_manager_->on_get_users(std::move(ptr->users_));
+
+    auto results = make_tl_object<td_api::connectedWebsites>();
+    results->websites_.reserve(ptr->authorizations_.size());
+    for (auto &authorization : ptr->authorizations_) {
+      CHECK(authorization != nullptr);
+      UserId bot_user_id(authorization->bot_id_);
+      if (!bot_user_id.is_valid()) {
+        LOG(ERROR) << "Receive invalid bot " << bot_user_id;
+        bot_user_id = UserId();
+      }
+
+      results->websites_.push_back(make_tl_object<td_api::connectedWebsite>(
+          authorization->hash_, authorization->domain_,
+          td->contacts_manager_->get_user_id_object(bot_user_id, "GetWebAuthorizationsQuery"), authorization->browser_,
+          authorization->platform_, authorization->date_created_, authorization->date_active_, authorization->ip_,
+          authorization->region_));
+    }
+
+    promise_.set_value(std::move(results));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ResetWebAuthorizationQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit ResetWebAuthorizationQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int64 hash) {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::account_resetWebAuthorization(hash))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::account_resetWebAuthorization>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.move_as_ok();
+    LOG_IF(WARNING, !result) << "Failed to disconnect website";
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ResetWebAuthorizationsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit ResetWebAuthorizationsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::account_resetWebAuthorizations())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::account_resetWebAuthorizations>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.move_as_ok();
+    LOG_IF(WARNING, !result) << "Failed to disconnect all websites";
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class BlockUserQuery : public Td::ResultHandler {
+ public:
+  void send(tl_object_ptr<telegram_api::InputUser> &&user) {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::contacts_block(std::move(user)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::contacts_block>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    LOG_IF(WARNING, !result) << "Block user has failed";
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(WARNING) << "Receive error for blockUser: " << status;
+    status.ignore();
+  }
+};
+
+class UnblockUserQuery : public Td::ResultHandler {
+ public:
+  void send(tl_object_ptr<telegram_api::InputUser> &&user) {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::contacts_unblock(std::move(user)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::contacts_unblock>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    LOG_IF(WARNING, !result) << "Unblock user has failed";
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(WARNING) << "Receive error for unblockUser: " << status;
+    status.ignore();
+  }
+};
+
+class GetBlockedUsersQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  int32 offset_;
+  int32 limit_;
+  int64 random_id_;
+
+ public:
+  explicit GetBlockedUsersQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int32 offset, int32 limit, int64 random_id) {
+    offset_ = offset;
+    limit_ = limit;
+    random_id_ = random_id;
+
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::contacts_getBlocked(offset, limit))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::contacts_getBlocked>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for GetBlockedUsersQuery: " << to_string(ptr);
+
+    int32 constructor_id = ptr->get_id();
+    switch (constructor_id) {
+      case telegram_api::contacts_blocked::ID: {
+        auto blocked_users = move_tl_object_as<telegram_api::contacts_blocked>(ptr);
+
+        td->contacts_manager_->on_get_users(std::move(blocked_users->users_));
+        td->contacts_manager_->on_get_blocked_users_result(offset_, limit_, random_id_,
+                                                           narrow_cast<int32>(blocked_users->blocked_.size()),
+                                                           std::move(blocked_users->blocked_));
+        break;
+      }
+      case telegram_api::contacts_blockedSlice::ID: {
+        auto blocked_users = move_tl_object_as<telegram_api::contacts_blockedSlice>(ptr);
+
+        td->contacts_manager_->on_get_users(std::move(blocked_users->users_));
+        td->contacts_manager_->on_get_blocked_users_result(offset_, limit_, random_id_, blocked_users->count_,
+                                                           std::move(blocked_users->blocked_));
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_failed_get_blocked_users(random_id_);
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetContactsQuery : public Td::ResultHandler {
+ public:
+  void send(int32 hash) {
+    LOG(INFO) << "Reload contacts with hash " << hash;
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::contacts_getContacts(hash))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::contacts_getContacts>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for getContacts: " << to_string(ptr);
+    td->contacts_manager_->on_get_contacts(std::move(ptr));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_contacts_failed(std::move(status));
+    td->updates_manager_->get_difference("GetContactsQuery");
+  }
+};
+
+class GetContactsStatusesQuery : public Td::ResultHandler {
+ public:
+  void send() {
+    LOG(INFO) << "Reload contacts statuses";
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::contacts_getStatuses())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::contacts_getStatuses>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->contacts_manager_->on_get_contacts_statuses(result_ptr.move_as_ok());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for getContactsStatuses: " << status;
+  }
+};
+
+class ImportContactsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  vector<Contact> input_contacts_;
+  vector<UserId> imported_user_ids_;
+  vector<int32> unimported_contact_invites_;
+  int64 random_id_;
+
+ public:
+  explicit ImportContactsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(vector<Contact> input_contacts, int64 random_id) {
+    random_id_ = random_id;
+
+    size_t size = input_contacts.size();
+    if (size == 0) {
+      td->contacts_manager_->on_imported_contacts(random_id, std::move(imported_user_ids_),
+                                                  std::move(unimported_contact_invites_));
+      promise_.set_value(Unit());
+      return;
+    }
+
+    imported_user_ids_.resize(size);
+    unimported_contact_invites_.resize(size);
+    input_contacts_ = std::move(input_contacts);
+
+    vector<tl_object_ptr<telegram_api::inputPhoneContact>> contacts;
+    contacts.reserve(size);
+    for (size_t i = 0; i < size; i++) {
+      contacts.push_back(input_contacts_[i].get_input_phone_contact(static_cast<int64>(i)));
+    }
+
+    send_query(
+        G()->net_query_creator().create(create_storer(telegram_api::contacts_importContacts(std::move(contacts)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::contacts_importContacts>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for importContacts: " << to_string(ptr);
+
+    td->contacts_manager_->on_get_users(std::move(ptr->users_));
+    for (auto &imported_contact : ptr->imported_) {
+      int64 client_id = imported_contact->client_id_;
+      if (client_id < 0 || client_id >= static_cast<int64>(imported_user_ids_.size())) {
+        LOG(ERROR) << "Wrong client_id " << client_id << " returned";
+        continue;
+      }
+
+      imported_user_ids_[static_cast<size_t>(client_id)] = UserId(imported_contact->user_id_);
+    }
+    for (auto &popular_contact : ptr->popular_invites_) {
+      int64 client_id = popular_contact->client_id_;
+      if (client_id < 0 || client_id >= static_cast<int64>(unimported_contact_invites_.size())) {
+        LOG(ERROR) << "Wrong client_id " << client_id << " returned";
+        continue;
+      }
+      if (popular_contact->importers_ < 0) {
+        LOG(ERROR) << "Wrong number of importers " << popular_contact->importers_ << " returned";
+        continue;
+      }
+
+      unimported_contact_invites_[static_cast<size_t>(client_id)] = popular_contact->importers_;
+    }
+
+    if (!ptr->retry_contacts_.empty()) {
+      int64 total_size = static_cast<int64>(input_contacts_.size());
+      vector<tl_object_ptr<telegram_api::inputPhoneContact>> contacts;
+      contacts.reserve(ptr->retry_contacts_.size());
+      for (auto &client_id : ptr->retry_contacts_) {
+        if (client_id < 0 || client_id >= total_size) {
+          LOG(ERROR) << "Wrong client_id " << client_id << " returned";
+          continue;
+        }
+        size_t i = static_cast<size_t>(client_id);
+        contacts.push_back(input_contacts_[i].get_input_phone_contact(client_id));
+      }
+
+      send_query(
+          G()->net_query_creator().create(create_storer(telegram_api::contacts_importContacts(std::move(contacts)))));
+      return;
+    }
+
+    td->contacts_manager_->on_imported_contacts(random_id_, std::move(imported_user_ids_),
+                                                std::move(unimported_contact_invites_));
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+    td->contacts_manager_->reload_contacts(true);
+  }
+};
+
+class DeleteContactsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  vector<UserId> user_ids_;
+
+ public:
+  explicit DeleteContactsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(vector<UserId> &&user_ids, vector<tl_object_ptr<telegram_api::InputUser>> &&input_users) {
+    user_ids_ = std::move(user_ids);
+    send_query(
+        G()->net_query_creator().create(create_storer(telegram_api::contacts_deleteContacts(std::move(input_users)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::contacts_deleteContacts>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    if (!result) {
+      return on_error(id, Status::Error(500, "Some contacts can't be deleted"));
+    }
+
+    td->contacts_manager_->on_deleted_contacts(user_ids_);
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+    td->contacts_manager_->reload_contacts(true);
+  }
+};
+
+class ResetContactsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit ResetContactsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::contacts_resetSaved())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::contacts_resetSaved>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    if (!result) {
+      LOG(ERROR) << "Failed to delete imported contacts";
+      td->contacts_manager_->reload_contacts(true);
+    } else {
+      td->contacts_manager_->on_update_contacts_reset();
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+    td->contacts_manager_->reload_contacts(true);
+  }
+};
+
+class UploadProfilePhotoQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  FileId file_id_;
+
+ public:
+  explicit UploadProfilePhotoQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(FileId file_id, tl_object_ptr<telegram_api::InputFile> &&input_file) {
+    CHECK(input_file != nullptr);
+    CHECK(file_id.is_valid());
+
+    file_id_ = file_id;
+
+    send_query(
+        G()->net_query_creator().create(create_storer(telegram_api::photos_uploadProfilePhoto(std::move(input_file)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::photos_uploadProfilePhoto>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for uploadProfilePhoto: " << to_string(ptr);
+    td->contacts_manager_->on_get_users(std::move(ptr->users_));
+
+    td->file_manager_->delete_partial_remote_location(file_id_);
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+    td->file_manager_->delete_partial_remote_location(file_id_);
+    td->updates_manager_->get_difference("UploadProfilePhotoQuery");
+  }
+};
+
+class UpdateProfilePhotoQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit UpdateProfilePhotoQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(tl_object_ptr<telegram_api::InputPhoto> &&input_photo) {
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::photos_updateProfilePhoto(std::move(input_photo)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::photos_updateProfilePhoto>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    LOG(DEBUG) << "Receive result for updateProfilePhoto " << to_string(result_ptr.ok());
+    td->contacts_manager_->on_update_user_photo(td->contacts_manager_->get_my_id("UpdateProfilePhotoQuery"),
+                                                result_ptr.move_as_ok());
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class DeleteProfilePhotoQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  int64 profile_photo_id_;
+
+ public:
+  explicit DeleteProfilePhotoQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int64 profile_photo_id) {
+    profile_photo_id_ = profile_photo_id;
+    vector<tl_object_ptr<telegram_api::InputPhoto>> input_photo_ids;
+    input_photo_ids.push_back(make_tl_object<telegram_api::inputPhoto>(profile_photo_id, 0));
+    send_query(
+        G()->net_query_creator().create(create_storer(telegram_api::photos_deletePhotos(std::move(input_photo_ids)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::photos_deletePhotos>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto result = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for deleteProfilePhoto " << format::as_array(result);
+    if (result.size() != 1u) {
+      LOG(WARNING) << "Photo can't be deleted";
+      return on_error(id, Status::Error(7, "Photo can't be deleted"));
+    }
+
+    td->contacts_manager_->on_delete_profile_photo(profile_photo_id_, std::move(promise_));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class UpdateProfileQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  int32 flags_;
+  string first_name_;
+  string last_name_;
+  string about_;
+
+ public:
+  explicit UpdateProfileQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int32 flags, const string &first_name, const string &last_name, const string &about) {
+    flags_ = flags;
+    first_name_ = first_name;
+    last_name_ = last_name;
+    about_ = about;
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::account_updateProfile(flags, first_name, last_name, about))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::account_updateProfile>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    LOG(DEBUG) << "Receive result for updateProfile " << to_string(result_ptr.ok());
+    td->contacts_manager_->on_get_user(result_ptr.move_as_ok());
+    td->contacts_manager_->on_update_profile_success(flags_, first_name_, last_name_, about_);
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class CheckUsernameQuery : public Td::ResultHandler {
+  Promise<bool> promise_;
+
+ public:
+  explicit CheckUsernameQuery(Promise<bool> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(const string &username) {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::account_checkUsername(username))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::account_checkUsername>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    promise_.set_value(result_ptr.move_as_ok());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class UpdateUsernameQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit UpdateUsernameQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(const string &username) {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::account_updateUsername(username))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::account_updateUsername>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    LOG(DEBUG) << "Receive result for updateUsername " << to_string(result_ptr.ok());
+    td->contacts_manager_->on_get_user(result_ptr.move_as_ok());
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.message() == "USERNAME_NOT_MODIFIED" && !td->auth_manager_->is_bot()) {
+      promise_.set_value(Unit());
+      return;
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ToggleChatAdminsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit ToggleChatAdminsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChatId chat_id, bool everyone_is_administrator) {
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_toggleChatAdmins(chat_id.get(), !everyone_is_administrator))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_toggleChatAdmins>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for toggleChatAdmins: " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.message() == "CHAT_NOT_MODIFIED" && !td->auth_manager_->is_bot()) {
+      promise_.set_value(Unit());
+      return;
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class CheckChannelUsernameQuery : public Td::ResultHandler {
+  Promise<bool> promise_;
+  ChannelId channel_id_;
+  string username_;
+
+ public:
+  explicit CheckChannelUsernameQuery(Promise<bool> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, const string &username) {
+    channel_id_ = channel_id;
+    tl_object_ptr<telegram_api::InputChannel> input_channel;
+    if (channel_id.is_valid()) {
+      input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    } else {
+      input_channel = make_tl_object<telegram_api::inputChannelEmpty>();
+    }
+    CHECK(input_channel != nullptr);
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::channels_checkUsername(std::move(input_channel), username))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_checkUsername>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    promise_.set_value(result_ptr.move_as_ok());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (channel_id_.is_valid()) {
+      td->contacts_manager_->on_get_channel_error(channel_id_, status, "CheckChannelUsernameQuery");
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class UpdateChannelUsernameQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+  string username_;
+
+ public:
+  explicit UpdateChannelUsernameQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, const string &username) {
+    channel_id_ = channel_id;
+    username_ = username;
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::channels_updateUsername(std::move(input_channel), username))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_updateUsername>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    LOG(DEBUG) << "Receive result for updateChannelUsername " << result;
+    if (!result) {
+      return on_error(id, Status::Error(500, "Supergroup username is not updated"));
+    }
+
+    td->contacts_manager_->on_update_channel_username(channel_id_, std::move(username_));
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.message() == "USERNAME_NOT_MODIFIED" || status.message() == "CHAT_NOT_MODIFIED") {
+      td->contacts_manager_->on_update_channel_username(channel_id_, std::move(username_));
+      if (!td->auth_manager_->is_bot()) {
+        promise_.set_value(Unit());
+        return;
+      }
+    } else {
+      td->contacts_manager_->on_get_channel_error(channel_id_, status, "UpdateChannelUsernameQuery");
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SetChannelStickerSetQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+  int64 sticker_set_id_;
+
+ public:
+  explicit SetChannelStickerSetQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, int64 sticker_set_id,
+            telegram_api::object_ptr<telegram_api::InputStickerSet> &&input_sticker_set) {
+    channel_id_ = channel_id;
+    sticker_set_id_ = sticker_set_id;
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::channels_setStickers(std::move(input_channel), std::move(input_sticker_set)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_setStickers>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    LOG(DEBUG) << "Receive result for setChannelStickerSet " << result;
+    if (!result) {
+      return on_error(id, Status::Error(500, "Supergroup sticker set not updated"));
+    }
+
+    td->contacts_manager_->on_update_channel_sticker_set(channel_id_, sticker_set_id_);
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.message() == "CHAT_NOT_MODIFIED") {
+      td->contacts_manager_->on_update_channel_sticker_set(channel_id_, sticker_set_id_);
+      if (!td->auth_manager_->is_bot()) {
+        promise_.set_value(Unit());
+        return;
+      }
+    } else {
+      td->contacts_manager_->on_get_channel_error(channel_id_, status, "SetChannelStickerSetQuery");
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ToggleChannelInvitesQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+
+ public:
+  explicit ToggleChannelInvitesQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, bool anyone_can_invite) {
+    channel_id_ = channel_id;
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::channels_toggleInvites(std::move(input_channel), anyone_can_invite))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_toggleInvites>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for toggleChannelInvites: " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.message() == "CHAT_NOT_MODIFIED") {
+      if (!td->auth_manager_->is_bot()) {
+        promise_.set_value(Unit());
+        return;
+      }
+    } else {
+      td->contacts_manager_->on_get_channel_error(channel_id_, status, "ToggleChannelInvitesQuery");
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ToggleChannelSignaturesQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+
+ public:
+  explicit ToggleChannelSignaturesQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, bool sign_messages) {
+    channel_id_ = channel_id;
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::channels_toggleSignatures(std::move(input_channel), sign_messages))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_toggleSignatures>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for toggleChannelSignatures: " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.message() == "CHAT_NOT_MODIFIED") {
+      if (!td->auth_manager_->is_bot()) {
+        promise_.set_value(Unit());
+        return;
+      }
+    } else {
+      td->contacts_manager_->on_get_channel_error(channel_id_, status, "ToggleChannelSignaturesQuery");
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ToggleChannelIsAllHistoryAvailableQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+  bool is_all_history_available_;
+
+ public:
+  explicit ToggleChannelIsAllHistoryAvailableQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, bool is_all_history_available) {
+    channel_id_ = channel_id;
+    is_all_history_available_ = is_all_history_available;
+
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+    send_query(G()->net_query_creator().create(create_storer(
+        telegram_api::channels_togglePreHistoryHidden(std::move(input_channel), !is_all_history_available))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_togglePreHistoryHidden>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for togglePreHistoryHidden: " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+    td->contacts_manager_->on_update_channel_is_all_history_available(channel_id_, is_all_history_available_);
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.message() == "CHAT_NOT_MODIFIED") {
+      if (!td->auth_manager_->is_bot()) {
+        promise_.set_value(Unit());
+        return;
+      }
+    } else {
+      td->contacts_manager_->on_get_channel_error(channel_id_, status, "ToggleChannelIsAllHistoryAvailableQuery");
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class EditChannelAboutQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+  string about_;
+
+ public:
+  explicit EditChannelAboutQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, const string &about) {
+    channel_id_ = channel_id;
+    about_ = about;
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::channels_editAbout(std::move(input_channel), about))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_editAbout>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    LOG(DEBUG) << "Receive result for editChannelAbout " << result;
+    if (!result) {
+      return on_error(id, Status::Error(500, "Supergroup description is not updated"));
+    }
+
+    td->contacts_manager_->on_update_channel_description(channel_id_, std::move(about_));
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.message() == "CHAT_ABOUT_NOT_MODIFIED" || status.message() == "CHAT_NOT_MODIFIED") {
+      td->contacts_manager_->on_update_channel_description(channel_id_, std::move(about_));
+      if (!td->auth_manager_->is_bot()) {
+        promise_.set_value(Unit());
+        return;
+      }
+    } else {
+      td->contacts_manager_->on_get_channel_error(channel_id_, status, "EditChannelAboutQuery");
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class UpdateChannelPinnedMessageQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+  MessageId message_id_;
+
+ public:
+  explicit UpdateChannelPinnedMessageQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, MessageId message_id, bool disable_notification) {
+    channel_id_ = channel_id;
+    message_id_ = message_id;
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+
+    int32 flags = 0;
+    if (disable_notification) {
+      flags |= telegram_api::channels_updatePinnedMessage::SILENT_MASK;
+    }
+
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::channels_updatePinnedMessage(
+        flags, false /*ignored*/, std::move(input_channel), message_id.get_server_message_id().get()))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_updatePinnedMessage>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for updateChannelPinnedMessage: " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.message() == "CHAT_NOT_MODIFIED") {
+      td->contacts_manager_->on_update_channel_pinned_message(channel_id_, message_id_);
+      if (!td->auth_manager_->is_bot()) {
+        promise_.set_value(Unit());
+        return;
+      }
+    } else {
+      td->contacts_manager_->on_get_channel_error(channel_id_, status, "UpdateChannelPinnedMessageQuery");
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ReportChannelSpamQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+
+ public:
+  explicit ReportChannelSpamQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, UserId user_id, const vector<MessageId> &message_ids) {
+    LOG(INFO) << "Send reportChannelSpamQuery in " << channel_id << " with messages " << format::as_array(message_ids)
+              << " and " << user_id;
+    channel_id_ = channel_id;
+
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+
+    auto input_user = td->contacts_manager_->get_input_user(user_id);
+    CHECK(input_user != nullptr);
+
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::channels_reportSpam(
+        std::move(input_channel), std::move(input_user), MessagesManager::get_server_message_ids(message_ids)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_reportSpam>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.move_as_ok();
+    LOG_IF(INFO, !result) << "Report spam has failed";
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "ReportChannelSpamQuery");
+    status.ignore();
+  }
+};
+
+class DeleteChannelQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+
+ public:
+  explicit DeleteChannelQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id) {
+    channel_id_ = channel_id;
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+    send_query(
+        G()->net_query_creator().create(create_storer(telegram_api::channels_deleteChannel(std::move(input_channel)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_deleteChannel>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for deleteChannel: " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "DeleteChannelQuery");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class AddChatUserQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit AddChatUserQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChatId chat_id, tl_object_ptr<telegram_api::InputUser> &&input_user, int32 forward_limit) {
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_addChatUser(chat_id.get(), std::move(input_user), forward_limit))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_addChatUser>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for addChatUser: " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+    td->updates_manager_->get_difference("AddChatUserQuery");
+  }
+};
+
+class EditChatAdminQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChatId chat_id_;
+
+ public:
+  explicit EditChatAdminQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChatId chat_id, tl_object_ptr<telegram_api::InputUser> &&input_user, bool is_administrator) {
+    chat_id_ = chat_id;
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_editChatAdmin(chat_id.get(), std::move(input_user), is_administrator))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_editChatAdmin>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.move_as_ok();
+    if (!result) {
+      LOG(ERROR) << "Receive false as result of messages.editChatAdmin";
+      return on_error(id, Status::Error(400, "Can't edit chat administrators"));
+    }
+
+    // result will come in the updates
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+    td->updates_manager_->get_difference("EditChatAdminQuery");
+  }
+};
+
+class ExportChatInviteLinkQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChatId chat_id_;
+
+ public:
+  explicit ExportChatInviteLinkQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChatId chat_id) {
+    chat_id_ = chat_id;
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_exportChatInvite(chat_id.get()))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_exportChatInvite>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for exportChatInvite: " << to_string(ptr);
+
+    td->contacts_manager_->on_get_chat_invite_link(chat_id_, std::move(ptr));
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+    td->updates_manager_->get_difference("ExportChatInviteLinkQuery");
+  }
+};
+
+class ExportChannelInviteLinkQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+
+ public:
+  explicit ExportChannelInviteLinkQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id) {
+    channel_id_ = channel_id;
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+    send_query(
+        G()->net_query_creator().create(create_storer(telegram_api::channels_exportInvite(std::move(input_channel)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_exportInvite>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for exportChannelInvite: " << to_string(ptr);
+
+    td->contacts_manager_->on_get_channel_invite_link(channel_id_, std::move(ptr));
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "ExportChannelInviteLinkQuery");
+    promise_.set_error(std::move(status));
+    td->updates_manager_->get_difference("ExportChannelInviteLinkQuery");
+  }
+};
+
+class CheckDialogInviteLinkQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  string invite_link_;
+
+ public:
+  explicit CheckDialogInviteLinkQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(const string &invite_link) {
+    invite_link_ = invite_link;
+    send_query(G()->net_query_creator().create(create_storer(
+        telegram_api::messages_checkChatInvite(ContactsManager::get_dialog_invite_link_hash(invite_link_).str()))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_checkChatInvite>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for checkChatInvite: " << to_string(ptr);
+
+    td->contacts_manager_->on_get_dialog_invite_link_info(invite_link_, std::move(ptr));
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ImportDialogInviteLinkQuery : public Td::ResultHandler {
+  Promise<DialogId> promise_;
+
+  string invite_link_;
+
+ public:
+  explicit ImportDialogInviteLinkQuery(Promise<DialogId> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(const string &invite_link) {
+    invite_link_ = invite_link;
+    send_query(G()->net_query_creator().create(create_storer(
+        telegram_api::messages_importChatInvite(ContactsManager::get_dialog_invite_link_hash(invite_link).str()))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_importChatInvite>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for importChatInvite: " << to_string(ptr);
+
+    auto dialog_ids = td->updates_manager_->get_chats(ptr.get());
+    if (dialog_ids.size() != 1u) {
+      LOG(ERROR) << "Receive wrong result for ImportDialogInviteLinkQuery: " << to_string(ptr);
+      return on_error(id, Status::Error(500, "Internal Server Error"));
+    }
+
+    td->updates_manager_->on_get_updates(std::move(ptr));
+    td->contacts_manager_->invalidate_invite_link(invite_link_);
+    promise_.set_value(std::move(dialog_ids[0]));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->invalidate_invite_link(invite_link_);
+    promise_.set_error(std::move(status));
+  }
+};
+
+class DeleteChatUserQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit DeleteChatUserQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChatId chat_id, tl_object_ptr<telegram_api::InputUser> &&input_user) {
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_deleteChatUser(chat_id.get(), std::move(input_user)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_deleteChatUser>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for deleteChatUser: " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+    td->updates_manager_->get_difference("DeleteChatUserQuery");
+  }
+};
+
+class JoinChannelQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+
+ public:
+  explicit JoinChannelQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id) {
+    channel_id_ = channel_id;
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+    send_query(
+        G()->net_query_creator().create(create_storer(telegram_api::channels_joinChannel(std::move(input_channel)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_joinChannel>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for joinChannel: " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "JoinChannelQuery");
+    promise_.set_error(std::move(status));
+    td->updates_manager_->get_difference("JoinChannelQuery");
+  }
+};
+
+class InviteToChannelQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+
+ public:
+  explicit InviteToChannelQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, vector<tl_object_ptr<telegram_api::InputUser>> &&input_users) {
+    channel_id_ = channel_id;
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::channels_inviteToChannel(std::move(input_channel), std::move(input_users)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_inviteToChannel>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for inviteToChannel: " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+    td->contacts_manager_->invalidate_channel_full(channel_id_);
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "InviteToChannelQuery");
+    promise_.set_error(std::move(status));
+    td->updates_manager_->get_difference("InviteToChannelQuery");
+  }
+};
+
+class EditChannelAdminQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+
+ public:
+  explicit EditChannelAdminQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, tl_object_ptr<telegram_api::InputUser> &&input_user, DialogParticipantStatus status) {
+    channel_id_ = channel_id;
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::channels_editAdmin(
+        std::move(input_channel), std::move(input_user), status.get_channel_admin_rights()))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_editAdmin>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for editChannelAdmin: " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+    td->contacts_manager_->invalidate_channel_full(channel_id_);
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "EditChannelAdminQuery");
+    promise_.set_error(std::move(status));
+    td->updates_manager_->get_difference("EditChannelAdminQuery");
+  }
+};
+
+class EditChannelBannedQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+
+ public:
+  explicit EditChannelBannedQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, tl_object_ptr<telegram_api::InputUser> &&input_user, DialogParticipantStatus status) {
+    channel_id_ = channel_id;
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::channels_editBanned(
+        std::move(input_channel), std::move(input_user), status.get_channel_banned_rights()))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_editBanned>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for editChannelBanned: " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+    td->contacts_manager_->invalidate_channel_full(channel_id_);
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "EditChannelBannedQuery");
+    promise_.set_error(std::move(status));
+    td->updates_manager_->get_difference("EditChannelBannedQuery");
+  }
+};
+
+class LeaveChannelQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+
+ public:
+  explicit LeaveChannelQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id) {
+    channel_id_ = channel_id;
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+    send_query(
+        G()->net_query_creator().create(create_storer(telegram_api::channels_leaveChannel(std::move(input_channel)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_leaveChannel>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for leaveChannel: " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "LeaveChannelQuery");
+    promise_.set_error(std::move(status));
+    td->updates_manager_->get_difference("LeaveChannelQuery");
+  }
+};
+
+class MigrateChatQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit MigrateChatQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChatId chat_id) {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_migrateChat(chat_id.get()))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_migrateChat>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for migrateChat: " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+    td->updates_manager_->get_difference("MigrateChatQuery");
+  }
+};
+
+class GetCreatedPublicChannelsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit GetCreatedPublicChannelsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::channels_getAdminedPublicChannels())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_getAdminedPublicChannels>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto chats_ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for GetCreatedPublicChannelsQuery " << to_string(chats_ptr);
+    int32 constructor_id = chats_ptr->get_id();
+    switch (constructor_id) {
+      case telegram_api::messages_chats::ID: {
+        auto chats = move_tl_object_as<telegram_api::messages_chats>(chats_ptr);
+        td->contacts_manager_->on_get_created_public_channels(std::move(chats->chats_));
+        break;
+      }
+      case telegram_api::messages_chatsSlice::ID: {
+        auto chats = move_tl_object_as<telegram_api::messages_chatsSlice>(chats_ptr);
+        LOG(ERROR) << "Receive chatsSlice in result of GetCreatedPublicChannelsQuery";
+        td->contacts_manager_->on_get_created_public_channels(std::move(chats->chats_));
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetUsersQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit GetUsersQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(vector<tl_object_ptr<telegram_api::InputUser>> &&input_users) {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::users_getUsers(std::move(input_users)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::users_getUsers>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->contacts_manager_->on_get_users(result_ptr.move_as_ok());
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetFullUserQuery : public Td::ResultHandler {
+  UserId user_id_;
+
+ public:
+  void send(UserId user_id, tl_object_ptr<telegram_api::InputUser> &&input_user) {
+    user_id_ = user_id;
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::users_getFullUser(std::move(input_user)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::users_getFullUser>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    LOG(DEBUG) << "Receive result for getFullUser " << to_string(result_ptr.ok());
+    td->contacts_manager_->on_get_user_full(result_ptr.move_as_ok());
+    td->contacts_manager_->on_get_user_full_success(user_id_);
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_user_full_fail(user_id_, std::move(status));
+  }
+};
+
+class GetUserPhotosQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  UserId user_id_;
+  int32 offset_;
+  int32 limit_;
+
+ public:
+  explicit GetUserPhotosQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(UserId user_id, tl_object_ptr<telegram_api::InputUser> &&input_user, int32 offset, int32 limit) {
+    user_id_ = user_id;
+    offset_ = offset;
+    limit_ = limit;
+    LOG(INFO) << "Get " << user_id << " profile photos with offset " << offset << " and limit " << limit;
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::photos_getUserPhotos(std::move(input_user), offset, 0, limit))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::photos_getUserPhotos>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+
+    LOG(INFO) << "Receive result for GetUserPhotosQuery " << to_string(ptr);
+    int32 constructor_id = ptr->get_id();
+    if (constructor_id == telegram_api::photos_photos::ID) {
+      auto photos = move_tl_object_as<telegram_api::photos_photos>(ptr);
+
+      td->contacts_manager_->on_get_users(std::move(photos->users_));
+      int32 photos_size = narrow_cast<int32>(photos->photos_.size());
+      td->contacts_manager_->on_get_user_photos(user_id_, offset_, limit_, photos_size, std::move(photos->photos_));
+    } else {
+      CHECK(constructor_id == telegram_api::photos_photosSlice::ID);
+      auto photos = move_tl_object_as<telegram_api::photos_photosSlice>(ptr);
+
+      td->contacts_manager_->on_get_users(std::move(photos->users_));
+      td->contacts_manager_->on_get_user_photos(user_id_, offset_, limit_, photos->count_, std::move(photos->photos_));
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetChatsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit GetChatsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(vector<int32> &&chat_ids) {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_getChats(std::move(chat_ids)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getChats>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto chats_ptr = result_ptr.move_as_ok();
+    int32 constructor_id = chats_ptr->get_id();
+    switch (constructor_id) {
+      case telegram_api::messages_chats::ID: {
+        auto chats = move_tl_object_as<telegram_api::messages_chats>(chats_ptr);
+        td->contacts_manager_->on_get_chats(std::move(chats->chats_));
+        break;
+      }
+      case telegram_api::messages_chatsSlice::ID: {
+        auto chats = move_tl_object_as<telegram_api::messages_chatsSlice>(chats_ptr);
+        LOG(ERROR) << "Receive chatsSlice in result of GetChatsQuery";
+        td->contacts_manager_->on_get_chats(std::move(chats->chats_));
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetFullChatQuery : public Td::ResultHandler {
+  ChatId chat_id_;
+
+ public:
+  void send(ChatId chat_id) {
+    chat_id_ = chat_id;
+    LOG(INFO) << "Send getFullChat query to get " << chat_id;
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_getFullChat(chat_id.get()))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getFullChat>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    //    LOG(INFO) << "Receive result for getFullChat query: " << to_string(ptr);
+    td->contacts_manager_->on_get_users(std::move(ptr->users_));
+    td->contacts_manager_->on_get_chats(std::move(ptr->chats_));
+    td->contacts_manager_->on_get_chat_full(std::move(ptr->full_chat_));
+
+    td->contacts_manager_->on_get_chat_full_success(chat_id_);
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_chat_full_fail(chat_id_, std::move(status));
+  }
+};
+
+class GetChannelsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+
+ public:
+  explicit GetChannelsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(tl_object_ptr<telegram_api::InputChannel> &&input_channel) {
+    CHECK(input_channel != nullptr);
+    if (input_channel->get_id() == telegram_api::inputChannel::ID) {
+      channel_id_ = ChannelId(static_cast<const telegram_api::inputChannel *>(input_channel.get())->channel_id_);
+    }
+
+    vector<tl_object_ptr<telegram_api::InputChannel>> input_channels;
+    input_channels.push_back(std::move(input_channel));
+    send_query(
+        G()->net_query_creator().create(create_storer(telegram_api::channels_getChannels(std::move(input_channels)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_getChannels>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    //    LOG(INFO) << "Receive result for getChannels query: " << to_string(result_ptr.ok());
+    auto chats_ptr = result_ptr.move_as_ok();
+    int32 constructor_id = chats_ptr->get_id();
+    switch (constructor_id) {
+      case telegram_api::messages_chats::ID: {
+        auto chats = move_tl_object_as<telegram_api::messages_chats>(chats_ptr);
+        td->contacts_manager_->on_get_chats(std::move(chats->chats_));
+        break;
+      }
+      case telegram_api::messages_chatsSlice::ID: {
+        auto chats = move_tl_object_as<telegram_api::messages_chatsSlice>(chats_ptr);
+        LOG(ERROR) << "Receive chatsSlice in result of GetChannelsQuery";
+        td->contacts_manager_->on_get_chats(std::move(chats->chats_));
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "GetChannelsQuery");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetFullChannelQuery : public Td::ResultHandler {
+  ChannelId channel_id_;
+
+ public:
+  void send(ChannelId channel_id, tl_object_ptr<telegram_api::InputChannel> &&input_channel) {
+    channel_id_ = channel_id;
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::channels_getFullChannel(std::move(input_channel)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_getFullChannel>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    //    LOG(INFO) << "Receive result for getFullChannel query: " << to_string(ptr);
+    td->contacts_manager_->on_get_users(std::move(ptr->users_));
+    td->contacts_manager_->on_get_chats(std::move(ptr->chats_));
+    td->contacts_manager_->on_get_chat_full(std::move(ptr->full_chat_));
+
+    td->contacts_manager_->on_get_channel_full_success(channel_id_);
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "GetFullChannelQuery");
+    td->contacts_manager_->on_get_channel_full_fail(channel_id_, std::move(status));
+  }
+};
+
+class GetChannelParticipantQuery : public Td::ResultHandler {
+  Promise<DialogParticipant> promise_;
+  ChannelId channel_id_;
+  UserId user_id_;
+
+ public:
+  explicit GetChannelParticipantQuery(Promise<DialogParticipant> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, UserId user_id, tl_object_ptr<telegram_api::InputUser> &&input_user) {
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    if (input_channel == nullptr) {
+      return promise_.set_error(Status::Error(3, "Supergroup not found"));
+    }
+
+    CHECK(input_user != nullptr);
+
+    channel_id_ = channel_id;
+    user_id_ = user_id;
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::channels_getParticipant(std::move(input_channel), std::move(input_user)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_getParticipant>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto participant = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for GetChannelParticipantQuery: " << to_string(participant);
+
+    td->contacts_manager_->on_get_users(std::move(participant->users_));
+    promise_.set_value(
+        td->contacts_manager_->get_dialog_participant(channel_id_, std::move(participant->participant_)));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.message() == "USER_NOT_PARTICIPANT") {
+      promise_.set_value({user_id_, UserId(), 0, DialogParticipantStatus::Left()});
+      return;
+    }
+
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "GetChannelParticipantQuery");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetChannelParticipantsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+  ChannelParticipantsFilter filter_{nullptr};
+  int32 offset_;
+  int32 limit_;
+  int64 random_id_;
+
+ public:
+  explicit GetChannelParticipantsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, ChannelParticipantsFilter filter, int32 offset, int32 limit, int64 random_id) {
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    if (input_channel == nullptr) {
+      return promise_.set_error(Status::Error(3, "Supergroup not found"));
+    }
+
+    channel_id_ = channel_id;
+    filter_ = std::move(filter);
+    offset_ = offset;
+    limit_ = limit;
+    random_id_ = random_id;
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::channels_getParticipants(
+        std::move(input_channel), filter_.get_input_channel_participants_filter(), offset, limit, 0))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_getParticipants>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto participants_ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for GetChannelParticipantsQuery with filter "
+              << to_string(filter_.get_input_channel_participants_filter()) << ": " << to_string(participants_ptr);
+    switch (participants_ptr->get_id()) {
+      case telegram_api::channels_channelParticipants::ID: {
+        auto participants = telegram_api::move_object_as<telegram_api::channels_channelParticipants>(participants_ptr);
+        td->contacts_manager_->on_get_users(std::move(participants->users_));
+        td->contacts_manager_->on_get_channel_participants_success(channel_id_, std::move(filter_), offset_, limit_,
+                                                                   random_id_, participants->count_,
+                                                                   std::move(participants->participants_));
+        break;
+      }
+      case telegram_api::channels_channelParticipantsNotModified::ID:
+        LOG(ERROR) << "Receive channelParticipantsNotModified";
+        break;
+      default:
+        UNREACHABLE();
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "GetChannelParticipantsQuery");
+    td->contacts_manager_->on_get_channel_participants_fail(channel_id_, std::move(filter_), offset_, limit_,
+                                                            random_id_);
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetChannelAdministratorsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+
+ public:
+  explicit GetChannelAdministratorsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, int32 hash) {
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    if (input_channel == nullptr) {
+      return promise_.set_error(Status::Error(3, "Supergroup not found"));
+    }
+
+    channel_id_ = channel_id;
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::channels_getParticipants(
+        std::move(input_channel), telegram_api::make_object<telegram_api::channelParticipantsAdmins>(), 0,
+        std::numeric_limits<int32>::max(), hash))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_getParticipants>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto participants_ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for GetChannelAdministratorsQuery: " << to_string(participants_ptr);
+    switch (participants_ptr->get_id()) {
+      case telegram_api::channels_channelParticipants::ID: {
+        auto participants = telegram_api::move_object_as<telegram_api::channels_channelParticipants>(participants_ptr);
+        td->contacts_manager_->on_get_users(std::move(participants->users_));
+        vector<UserId> administrator_user_ids;
+        administrator_user_ids.reserve(participants->participants_.size());
+        for (auto &participant : participants->participants_) {
+          UserId user_id;
+          downcast_call(*participant, [&user_id](auto &participant) { user_id = UserId(participant.user_id_); });
+          if (user_id.is_valid()) {
+            administrator_user_ids.push_back(user_id);
+          }
+        }
+
+        td->contacts_manager_->on_update_dialog_administrators(DialogId(channel_id_), std::move(administrator_user_ids),
+                                                               true);
+        break;
+      }
+      case telegram_api::channels_channelParticipantsNotModified::ID:
+        break;
+      default:
+        UNREACHABLE();
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "GetChannelAdministratorsQuery");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetSupportUserQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit GetSupportUserQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::help_getSupport())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::help_getSupport>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for GetSupportUserQuery: " << to_string(ptr);
+
+    td->contacts_manager_->on_get_user(std::move(ptr->user_), false, true);
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+StringBuilder &operator<<(StringBuilder &string_builder, ContactsManager::LinkState link_state) {
+  switch (link_state) {
+    case ContactsManager::LinkState::Unknown:
+      string_builder << "unknown";
+      break;
+    case ContactsManager::LinkState::None:
+      string_builder << "none";
+      break;
+    case ContactsManager::LinkState::KnowsPhoneNumber:
+      string_builder << "knows phone number";
+      break;
+    case ContactsManager::LinkState::Contact:
+      string_builder << "contact";
+      break;
+  }
+  return string_builder;
+}
+
+bool ContactsManager::UserFull::is_bot_info_expired(int32 bot_info_version) const {
+  return bot_info_version != -1 && (bot_info == nullptr || bot_info->version != bot_info_version);
+}
+
+bool ContactsManager::UserFull::is_expired() const {
+  return expires_at < Time::now();
+}
+
+bool ContactsManager::ChannelFull::is_expired() const {
+  return expires_at < Time::now();
+}
+
+class ContactsManager::OnChatUpdate {
+  ContactsManager *manager_;
+
+ public:
+  explicit OnChatUpdate(ContactsManager *manager) : manager_(manager) {
+  }
+
+  template <class T>
+  void operator()(T &func) const {
+    manager_->on_chat_update(func);
+  }
+};
+
+class ContactsManager::UploadProfilePhotoCallback : public FileManager::UploadCallback {
+ public:
+  void on_upload_ok(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) override {
+    send_closure_later(G()->contacts_manager(), &ContactsManager::on_upload_profile_photo, file_id,
+                       std::move(input_file));
+  }
+  void on_upload_encrypted_ok(FileId file_id, tl_object_ptr<telegram_api::InputEncryptedFile> input_file) override {
+    UNREACHABLE();
+  }
+  void on_upload_error(FileId file_id, Status error) override {
+    send_closure_later(G()->contacts_manager(), &ContactsManager::on_upload_profile_photo_error, file_id,
+                       std::move(error));
+  }
+};
+
+const CSlice ContactsManager::INVITE_LINK_URLS[3] = {"t.me/joinchat/", "telegram.me/joinchat/",
+                                                     "telegram.dog/joinchat/"};
+
+ContactsManager::ContactsManager(Td *td, ActorShared<> parent) : td_(td), parent_(std::move(parent)) {
+  upload_profile_photo_callback_ = std::make_shared<UploadProfilePhotoCallback>();
+
+  my_id_ = load_my_id();
+
+  if (G()->parameters().use_chat_info_db) {
+    auto next_contacts_sync_date_string = G()->td_db()->get_binlog_pmc()->get("next_contacts_sync_date");
+    if (!next_contacts_sync_date_string.empty()) {
+      next_contacts_sync_date_ = min(to_integer<int32>(next_contacts_sync_date_string), G()->unix_time() + 100000);
+    }
+
+    auto saved_contact_count_string = G()->td_db()->get_binlog_pmc()->get("saved_contact_count");
+    if (!saved_contact_count_string.empty()) {
+      saved_contact_count_ = to_integer<int32>(saved_contact_count_string);
+    }
+  } else {
+    G()->td_db()->get_binlog_pmc()->erase("next_contacts_sync_date");
+    G()->td_db()->get_binlog_pmc()->erase("saved_contact_count");
+  }
+
+  user_online_timeout_.set_callback(on_user_online_timeout_callback);
+  user_online_timeout_.set_callback_data(static_cast<void *>(this));
+
+  channel_unban_timeout_.set_callback(on_channel_unban_timeout_callback);
+  channel_unban_timeout_.set_callback_data(static_cast<void *>(this));
+}
+
+void ContactsManager::tear_down() {
+  parent_.reset();
+}
+
+UserId ContactsManager::load_my_id() {
+  auto id_string = G()->td_db()->get_binlog_pmc()->get("my_id");
+  if (!id_string.empty()) {
+    UserId my_id(to_integer<int32>(id_string));
+    if (my_id.is_valid()) {
+      return my_id;
+    }
+
+    my_id = UserId(to_integer<int32>(Slice(id_string).substr(5)));
+    if (my_id.is_valid()) {
+      G()->td_db()->get_binlog_pmc()->set("my_id", to_string(my_id.get()));
+      return my_id;
+    }
+
+    LOG(ERROR) << "Wrong my id = \"" << id_string << "\" stored in database";
+  }
+  return UserId();
+}
+
+void ContactsManager::on_user_online_timeout_callback(void *contacts_manager_ptr, int64 user_id_long) {
+  auto contacts_manager = static_cast<ContactsManager *>(contacts_manager_ptr);
+  UserId user_id(narrow_cast<int32>(user_id_long));
+  auto u = contacts_manager->get_user(user_id);
+  CHECK(u != nullptr);
+
+  LOG(INFO) << "Update " << user_id << " online status to offline";
+  send_closure_later(
+      G()->td(), &Td::send_update,
+      make_tl_object<td_api::updateUserStatus>(user_id.get(), contacts_manager->get_user_status_object(user_id, u)));
+}
+
+void ContactsManager::on_channel_unban_timeout_callback(void *contacts_manager_ptr, int64 channel_id_long) {
+  auto td = static_cast<ContactsManager *>(contacts_manager_ptr)->td_;
+  send_closure_later(td->actor_id(td), &Td::on_channel_unban_timeout, channel_id_long);
+}
+
+void ContactsManager::on_channel_unban_timeout(ChannelId channel_id) {
+  auto c = get_channel(channel_id);
+  CHECK(c != nullptr);
+
+  auto old_status = c->status;
+  c->status.update_restrictions();
+  LOG_IF(ERROR, c->status == old_status && (c->status.is_restricted() || c->status.is_banned()))
+      << "Status of " << channel_id << " wasn't updated: " << c->status;
+
+  LOG(INFO) << "Update " << channel_id << " status";
+  c->is_status_changed = true;
+  invalidate_channel_full(channel_id);
+  update_channel(c, channel_id);  // always call, because in case of failure we need to reactivate timeout
+}
+
+template <class StorerT>
+void ContactsManager::store_link_state(const LinkState &link_state, StorerT &storer) {
+  store(static_cast<uint32>(link_state), storer);
+}
+
+template <class ParserT>
+void ContactsManager::parse_link_state(LinkState &link_state, ParserT &parser) {
+  uint32 link_state_uint32;
+  parse(link_state_uint32, parser);
+  link_state = static_cast<LinkState>(static_cast<uint8>(link_state_uint32));
+}
+
+template <class StorerT>
+void ContactsManager::User::store(StorerT &storer) const {
+  using td::store;
+  bool has_last_name = !last_name.empty();
+  bool has_username = !username.empty();
+  bool has_photo = photo.small_file_id.is_valid();
+  bool is_restricted = !restriction_reason.empty();
+  bool has_language_code = !language_code.empty();
+  bool have_access_hash = access_hash != -1;
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(is_received);
+  STORE_FLAG(is_verified);
+  STORE_FLAG(is_deleted);
+  STORE_FLAG(is_bot);
+  STORE_FLAG(can_join_groups);
+  STORE_FLAG(can_read_all_group_messages);
+  STORE_FLAG(is_inline_bot);
+  STORE_FLAG(need_location_bot);
+  STORE_FLAG(has_last_name);
+  STORE_FLAG(has_username);
+  STORE_FLAG(has_photo);
+  STORE_FLAG(is_restricted);
+  STORE_FLAG(has_language_code);
+  STORE_FLAG(have_access_hash);
+  END_STORE_FLAGS();
+  store(first_name, storer);
+  if (has_last_name) {
+    store(last_name, storer);
+  }
+  if (has_username) {
+    store(username, storer);
+  }
+  store(phone_number, storer);
+  if (have_access_hash) {
+    store(access_hash, storer);
+  }
+  if (has_photo) {
+    store(photo, storer);
+  }
+  store_link_state(inbound, storer);
+  store_link_state(outbound, storer);
+  store(was_online, storer);
+  if (is_restricted) {
+    store(restriction_reason, storer);
+  }
+  if (is_inline_bot) {
+    store(inline_query_placeholder, storer);
+  }
+  if (is_bot) {
+    store(bot_info_version, storer);
+  }
+  if (has_language_code) {
+    store(language_code, storer);
+  }
+}
+
+template <class ParserT>
+void ContactsManager::User::parse(ParserT &parser) {
+  using td::parse;
+  bool has_last_name;
+  bool has_username;
+  bool has_photo;
+  bool is_restricted;
+  bool has_language_code;
+  bool have_access_hash;
+  BEGIN_PARSE_FLAGS();
+  PARSE_FLAG(is_received);
+  PARSE_FLAG(is_verified);
+  PARSE_FLAG(is_deleted);
+  PARSE_FLAG(is_bot);
+  PARSE_FLAG(can_join_groups);
+  PARSE_FLAG(can_read_all_group_messages);
+  PARSE_FLAG(is_inline_bot);
+  PARSE_FLAG(need_location_bot);
+  PARSE_FLAG(has_last_name);
+  PARSE_FLAG(has_username);
+  PARSE_FLAG(has_photo);
+  PARSE_FLAG(is_restricted);
+  PARSE_FLAG(has_language_code);
+  PARSE_FLAG(have_access_hash);
+  END_PARSE_FLAGS();
+  parse(first_name, parser);
+  if (has_last_name) {
+    parse(last_name, parser);
+  }
+  if (has_username) {
+    parse(username, parser);
+  }
+  parse(phone_number, parser);
+  if (parser.version() < static_cast<int32>(Version::FixMinUsers)) {
+    have_access_hash = is_received;
+  }
+  if (have_access_hash) {
+    parse(access_hash, parser);
+  }
+  if (has_photo) {
+    parse(photo, parser);
+  }
+  parse_link_state(inbound, parser);
+  parse_link_state(outbound, parser);
+  parse(was_online, parser);
+  if (is_restricted) {
+    parse(restriction_reason, parser);
+  }
+  if (is_inline_bot) {
+    parse(inline_query_placeholder, parser);
+  }
+  if (is_bot) {
+    parse(bot_info_version, parser);
+  }
+  if (has_language_code) {
+    parse(language_code, parser);
+  }
+  if (first_name.empty()) {
+    first_name = phone_number;
+  }
+}
+
+template <class StorerT>
+void ContactsManager::Chat::store(StorerT &storer) const {
+  using td::store;
+  bool has_photo = photo.small_file_id.is_valid();
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(left);
+  STORE_FLAG(kicked);
+  STORE_FLAG(is_creator);
+  STORE_FLAG(is_administrator);
+  STORE_FLAG(everyone_is_administrator);
+  STORE_FLAG(can_edit);
+  STORE_FLAG(is_active);
+  STORE_FLAG(has_photo);
+  END_STORE_FLAGS();
+
+  store(title, storer);
+  if (has_photo) {
+    store(photo, storer);
+  }
+  store(participant_count, storer);
+  store(date, storer);
+  store(migrated_to_channel_id, storer);
+  store(version, storer);
+}
+
+template <class ParserT>
+void ContactsManager::Chat::parse(ParserT &parser) {
+  using td::parse;
+  bool has_photo;
+  BEGIN_PARSE_FLAGS();
+  PARSE_FLAG(left);
+  PARSE_FLAG(kicked);
+  PARSE_FLAG(is_creator);
+  PARSE_FLAG(is_administrator);
+  PARSE_FLAG(everyone_is_administrator);
+  PARSE_FLAG(can_edit);
+  PARSE_FLAG(is_active);
+  PARSE_FLAG(has_photo);
+  END_PARSE_FLAGS();
+
+  parse(title, parser);
+  if (has_photo) {
+    parse(photo, parser);
+  }
+  parse(participant_count, parser);
+  parse(date, parser);
+  parse(migrated_to_channel_id, parser);
+  parse(version, parser);
+}
+
+template <class StorerT>
+void ContactsManager::Channel::store(StorerT &storer) const {
+  using td::store;
+  bool has_photo = photo.small_file_id.is_valid();
+  bool has_username = !username.empty();
+  bool is_restricted = !restriction_reason.empty();
+  bool use_new_rights = true;
+  bool have_participant_count = participant_count != 0;
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(false);
+  STORE_FLAG(false);
+  STORE_FLAG(anyone_can_invite);
+  STORE_FLAG(sign_messages);
+  STORE_FLAG(false);
+  STORE_FLAG(false);
+  STORE_FLAG(false);
+  STORE_FLAG(is_megagroup);
+  STORE_FLAG(is_verified);
+  STORE_FLAG(has_photo);
+  STORE_FLAG(has_username);
+  STORE_FLAG(is_restricted);
+  STORE_FLAG(use_new_rights);
+  STORE_FLAG(have_participant_count);
+  END_STORE_FLAGS();
+
+  store(status, storer);
+  store(access_hash, storer);
+  store(title, storer);
+  if (has_photo) {
+    store(photo, storer);
+  }
+  if (has_username) {
+    store(username, storer);
+  }
+  store(date, storer);
+  if (is_restricted) {
+    store(restriction_reason, storer);
+  }
+  if (have_participant_count) {
+    store(participant_count, storer);
+  }
+}
+
+template <class ParserT>
+void ContactsManager::Channel::parse(ParserT &parser) {
+  using td::parse;
+  bool has_photo;
+  bool has_username;
+  bool is_restricted;
+  bool left;
+  bool kicked;
+  bool is_creator;
+  bool can_edit;
+  bool can_moderate;
+  bool use_new_rights;
+  bool have_participant_count;
+  BEGIN_PARSE_FLAGS();
+  PARSE_FLAG(left);
+  PARSE_FLAG(kicked);
+  PARSE_FLAG(anyone_can_invite);
+  PARSE_FLAG(sign_messages);
+  PARSE_FLAG(is_creator);
+  PARSE_FLAG(can_edit);
+  PARSE_FLAG(can_moderate);
+  PARSE_FLAG(is_megagroup);
+  PARSE_FLAG(is_verified);
+  PARSE_FLAG(has_photo);
+  PARSE_FLAG(has_username);
+  PARSE_FLAG(is_restricted);
+  PARSE_FLAG(use_new_rights);
+  PARSE_FLAG(have_participant_count);
+  END_PARSE_FLAGS();
+
+  if (use_new_rights) {
+    parse(status, parser);
+  } else {
+    if (kicked) {
+      status = DialogParticipantStatus::Banned(0);
+    } else if (left) {
+      status = DialogParticipantStatus::Left();
+    } else if (is_creator) {
+      status = DialogParticipantStatus::Creator(true);
+    } else if (can_edit || can_moderate) {
+      status = DialogParticipantStatus::ChannelAdministrator(false, is_megagroup);
+    } else {
+      status = DialogParticipantStatus::Member();
+    }
+  }
+  parse(access_hash, parser);
+  parse(title, parser);
+  if (has_photo) {
+    parse(photo, parser);
+  }
+  if (has_username) {
+    parse(username, parser);
+  }
+  parse(date, parser);
+  if (is_restricted) {
+    parse(restriction_reason, parser);
+  }
+  if (have_participant_count) {
+    parse(participant_count, parser);
+  }
+}
+
+template <class StorerT>
+void ContactsManager::SecretChat::store(StorerT &storer) const {
+  using td::store;
+  bool has_layer = layer > SecretChatActor::DEFAULT_LAYER;
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(is_outbound);
+  STORE_FLAG(has_layer);
+  END_STORE_FLAGS();
+
+  store(access_hash, storer);
+  store(user_id, storer);
+  store(state, storer);
+  store(ttl, storer);
+  store(date, storer);
+  store(key_hash, storer);
+  if (has_layer) {
+    store(layer, storer);
+  }
+}
+
+template <class ParserT>
+void ContactsManager::SecretChat::parse(ParserT &parser) {
+  using td::parse;
+  bool has_layer;
+  BEGIN_PARSE_FLAGS();
+  PARSE_FLAG(is_outbound);
+  PARSE_FLAG(has_layer);
+  END_PARSE_FLAGS();
+
+  if (parser.version() >= static_cast<int32>(Version::AddAccessHashToSecretChat)) {
+    parse(access_hash, parser);
+  }
+  parse(user_id, parser);
+  parse(state, parser);
+  parse(ttl, parser);
+  parse(date, parser);
+  if (parser.version() >= static_cast<int32>(Version::AddKeyHashToSecretChat)) {
+    parse(key_hash, parser);
+  }
+  if (has_layer) {
+    parse(layer, parser);
+  } else {
+    layer = SecretChatActor::DEFAULT_LAYER;
+  }
+}
+
+tl_object_ptr<telegram_api::InputUser> ContactsManager::get_input_user(UserId user_id) const {
+  if (user_id == get_my_id("get_input_user")) {
+    return make_tl_object<telegram_api::inputUserSelf>();
+  }
+
+  const User *u = get_user(user_id);
+  if (u == nullptr || u->access_hash == -1) {
+    if (td_->auth_manager_->is_bot() && user_id.is_valid()) {
+      return make_tl_object<telegram_api::inputUser>(user_id.get(), 0);
+    }
+    return nullptr;
+  }
+
+  return make_tl_object<telegram_api::inputUser>(user_id.get(), u->access_hash);
+}
+
+bool ContactsManager::have_input_user(UserId user_id) const {
+  if (user_id == get_my_id("have_input_user")) {
+    return true;
+  }
+
+  const User *u = get_user(user_id);
+  if (u == nullptr || u->access_hash == -1) {
+    if (td_->auth_manager_->is_bot() && user_id.is_valid()) {
+      return true;
+    }
+    return false;
+  }
+
+  return true;
+}
+
+tl_object_ptr<telegram_api::InputChannel> ContactsManager::get_input_channel(ChannelId channel_id) const {
+  const Channel *c = get_channel(channel_id);
+  if (c == nullptr) {
+    if (td_->auth_manager_->is_bot() && channel_id.is_valid()) {
+      return make_tl_object<telegram_api::inputChannel>(channel_id.get(), 0);
+    }
+    return nullptr;
+  }
+
+  return make_tl_object<telegram_api::inputChannel>(channel_id.get(), c->access_hash);
+}
+
+bool ContactsManager::have_input_peer_user(UserId user_id, AccessRights access_rights) const {
+  if (user_id == get_my_id("have_input_peer_user")) {
+    return true;
+  }
+  return have_input_peer_user(get_user(user_id), access_rights);
+}
+
+bool ContactsManager::have_input_peer_user(const User *user, AccessRights access_rights) {
+  if (user == nullptr) {
+    return false;
+  }
+  if (user->access_hash == -1) {
+    return false;
+  }
+  if (access_rights == AccessRights::Read) {
+    return true;
+  }
+  if (user->is_deleted) {
+    return false;
+  }
+  return true;
+}
+
+tl_object_ptr<telegram_api::InputPeer> ContactsManager::get_input_peer_user(UserId user_id,
+                                                                            AccessRights access_rights) const {
+  if (user_id == get_my_id("get_input_peer_user")) {
+    return make_tl_object<telegram_api::inputPeerSelf>();
+  }
+  const User *u = get_user(user_id);
+  if (!have_input_peer_user(u, access_rights)) {
+    return nullptr;
+  }
+
+  return make_tl_object<telegram_api::inputPeerUser>(user_id.get(), u->access_hash);
+}
+
+bool ContactsManager::have_input_peer_chat(ChatId chat_id, AccessRights access_rights) const {
+  return have_input_peer_chat(get_chat(chat_id), access_rights);
+}
+
+bool ContactsManager::have_input_peer_chat(const Chat *chat, AccessRights access_rights) {
+  if (chat == nullptr) {
+    return false;
+  }
+  if (access_rights == AccessRights::Read) {
+    return true;
+  }
+  if (chat->left) {
+    return false;
+  }
+  if (access_rights == AccessRights::Write && !chat->is_active) {
+    return false;
+  }
+  return true;
+}
+
+tl_object_ptr<telegram_api::InputPeer> ContactsManager::get_input_peer_chat(ChatId chat_id,
+                                                                            AccessRights access_rights) const {
+  auto c = get_chat(chat_id);
+  if (!have_input_peer_chat(c, access_rights)) {
+    return nullptr;
+  }
+
+  return make_tl_object<telegram_api::inputPeerChat>(chat_id.get());
+}
+
+bool ContactsManager::have_input_peer_channel(ChannelId channel_id, AccessRights access_rights) const {
+  const Channel *c = get_channel(channel_id);
+  return have_input_peer_channel(c, access_rights);
+}
+
+tl_object_ptr<telegram_api::InputPeer> ContactsManager::get_input_peer_channel(ChannelId channel_id,
+                                                                               AccessRights access_rights) const {
+  const Channel *c = get_channel(channel_id);
+  if (!have_input_peer_channel(c, access_rights)) {
+    return nullptr;
+  }
+
+  return make_tl_object<telegram_api::inputPeerChannel>(channel_id.get(), c->access_hash);
+}
+
+bool ContactsManager::have_input_peer_channel(const Channel *c, AccessRights access_rights) {
+  if (c == nullptr) {
+    return false;
+  }
+  if (c->status.is_creator()) {
+    return true;
+  }
+  if (c->status.is_banned()) {
+    return false;
+  }
+  if (!c->username.empty() && access_rights == AccessRights::Read) {
+    return true;
+  }
+  if (!c->status.is_member()) {
+    return false;
+  }
+  return true;
+}
+
+bool ContactsManager::have_input_encrypted_peer(SecretChatId secret_chat_id, AccessRights access_rights) const {
+  return have_input_encrypted_peer(get_secret_chat(secret_chat_id), access_rights);
+}
+
+bool ContactsManager::have_input_encrypted_peer(const SecretChat *secret_chat, AccessRights access_rights) {
+  if (secret_chat == nullptr) {
+    return false;
+  }
+  if (access_rights == AccessRights::Read) {
+    return true;
+  }
+  return secret_chat->state == SecretChatState::Active;
+}
+
+tl_object_ptr<telegram_api::inputEncryptedChat> ContactsManager::get_input_encrypted_chat(
+    SecretChatId secret_chat_id, AccessRights access_rights) const {
+  auto sc = get_secret_chat(secret_chat_id);
+  if (!have_input_encrypted_peer(sc, access_rights)) {
+    return nullptr;
+  }
+
+  return make_tl_object<telegram_api::inputEncryptedChat>(secret_chat_id.get(), sc->access_hash);
+}
+
+const DialogPhoto *ContactsManager::get_user_dialog_photo(UserId user_id) const {
+  auto u = get_user(user_id);
+  if (u == nullptr) {
+    return nullptr;
+  }
+  return &u->photo;
+}
+
+const DialogPhoto *ContactsManager::get_chat_dialog_photo(ChatId chat_id) const {
+  auto c = get_chat(chat_id);
+  if (c == nullptr) {
+    return nullptr;
+  }
+  return &c->photo;
+}
+
+const DialogPhoto *ContactsManager::get_channel_dialog_photo(ChannelId channel_id) const {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return nullptr;
+  }
+  return &c->photo;
+}
+
+const DialogPhoto *ContactsManager::get_secret_chat_dialog_photo(SecretChatId secret_chat_id) const {
+  auto c = get_secret_chat(secret_chat_id);
+  if (c == nullptr) {
+    return nullptr;
+  }
+  return get_user_dialog_photo(c->user_id);
+}
+
+string ContactsManager::get_user_title(UserId user_id) const {
+  auto u = get_user(user_id);
+  if (u == nullptr) {
+    return string();
+  }
+  return u->last_name.empty() ? u->first_name : u->first_name + " " + u->last_name;
+}
+
+string ContactsManager::get_chat_title(ChatId chat_id) const {
+  auto c = get_chat(chat_id);
+  if (c == nullptr) {
+    return string();
+  }
+  return c->title;
+}
+
+string ContactsManager::get_channel_title(ChannelId channel_id) const {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return string();
+  }
+  return c->title;
+}
+
+string ContactsManager::get_secret_chat_title(SecretChatId secret_chat_id) const {
+  auto c = get_secret_chat(secret_chat_id);
+  if (c == nullptr) {
+    return string();
+  }
+  return get_user_title(c->user_id);
+}
+
+int32 ContactsManager::get_secret_chat_date(SecretChatId secret_chat_id) const {
+  auto c = get_secret_chat(secret_chat_id);
+  if (c == nullptr) {
+    return 0;
+  }
+  return c->date;
+}
+
+int32 ContactsManager::get_secret_chat_ttl(SecretChatId secret_chat_id) const {
+  auto c = get_secret_chat(secret_chat_id);
+  if (c == nullptr) {
+    return 0;
+  }
+  return c->ttl;
+}
+
+bool ContactsManager::default_can_report_spam_in_secret_chat(SecretChatId secret_chat_id) const {
+  auto c = get_secret_chat(secret_chat_id);
+  if (c == nullptr) {
+    return true;
+  }
+  if (c->is_outbound) {
+    return false;
+  }
+  auto u = get_user(c->user_id);
+  if (u == nullptr) {
+    return true;
+  }
+  if (u->outbound == LinkState::Contact) {
+    return false;
+  }
+  return true;
+}
+
+string ContactsManager::get_user_username(UserId user_id) const {
+  if (!user_id.is_valid()) {
+    return string();
+  }
+
+  auto u = get_user(user_id);
+  if (u == nullptr) {
+    return string();
+  }
+  return u->username;
+}
+
+string ContactsManager::get_secret_chat_username(SecretChatId secret_chat_id) const {
+  auto c = get_secret_chat(secret_chat_id);
+  if (c == nullptr) {
+    return string();
+  }
+  return get_user_username(c->user_id);
+}
+
+string ContactsManager::get_channel_username(ChannelId channel_id) const {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return string();
+  }
+  return c->username;
+}
+UserId ContactsManager::get_secret_chat_user_id(SecretChatId secret_chat_id) const {
+  auto c = get_secret_chat(secret_chat_id);
+  if (c == nullptr) {
+    return UserId();
+  }
+  return c->user_id;
+}
+
+SecretChatState ContactsManager::get_secret_chat_state(SecretChatId secret_chat_id) const {
+  auto c = get_secret_chat(secret_chat_id);
+  if (c == nullptr) {
+    return SecretChatState::Unknown;
+  }
+  return c->state;
+}
+
+int32 ContactsManager::get_secret_chat_layer(SecretChatId secret_chat_id) const {
+  auto c = get_secret_chat(secret_chat_id);
+  if (c == nullptr) {
+    return 0;
+  }
+  return c->layer;
+}
+
+UserId ContactsManager::get_my_id(const char *source) const {
+  LOG_IF(ERROR, !my_id_.is_valid()) << "Wrong or unknown my id returned to " << source;
+  return my_id_;
+}
+
+void ContactsManager::set_my_id(UserId my_id) {
+  UserId my_old_id = my_id_;
+  if (my_old_id.is_valid() && my_old_id != my_id) {
+    LOG(ERROR) << "Already know that me is " << my_old_id << " but received userSelf with " << my_id;
+  }
+  if (!my_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid my id " << my_id;
+    return;
+  }
+  if (my_old_id != my_id) {
+    my_id_ = my_id;
+    G()->td_db()->get_binlog_pmc()->set("my_id", to_string(my_id.get()));
+    G()->shared_config().set_option_integer("my_id", my_id_.get());
+  }
+}
+
+void ContactsManager::set_my_online_status(bool is_online, bool send_update, bool is_local) {
+  auto my_id = get_my_id("set_my_online_status");
+  User *u = get_user_force(my_id);
+  if (u != nullptr) {
+    int32 new_online;
+    int32 now = G()->unix_time();
+    if (is_online) {
+      new_online = now + 300;
+    } else {
+      new_online = now - 1;
+    }
+
+    if (is_local) {
+      LOG(INFO) << "Update my local online from " << my_was_online_local_ << " to " << new_online;
+      if (!is_online) {
+        new_online = min(new_online, u->was_online);
+      }
+      if (new_online != my_was_online_local_) {
+        my_was_online_local_ = new_online;
+        u->is_status_changed = true;
+      }
+    } else {
+      if (my_was_online_local_ != 0 || new_online != u->was_online) {
+        LOG(INFO) << "Update my online from " << u->was_online << " to " << new_online;
+        my_was_online_local_ = 0;
+        u->was_online = new_online;
+        u->is_status_changed = true;
+      }
+    }
+
+    if (send_update) {
+      update_user(u, my_id);
+    }
+  }
+}
+
+void ContactsManager::check_dialog_username(DialogId dialog_id, const string &username,
+                                            Promise<CheckDialogUsernameResult> &&promise) {
+  if (dialog_id != DialogId() && !dialog_id.is_valid()) {
+    return promise.set_error(Status::Error(3, "Chat not found"));
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User: {
+      if (dialog_id.get_user_id() != get_my_id("check_dialog_username")) {
+        return promise.set_error(Status::Error(3, "Can't check username for private chat with other user"));
+      }
+      break;
+    }
+    case DialogType::Channel: {
+      auto c = get_channel(dialog_id.get_channel_id());
+      if (c == nullptr) {
+        return promise.set_error(Status::Error(6, "Chat not found"));
+      }
+      if (!get_channel_status(c).is_creator()) {
+        return promise.set_error(Status::Error(6, "Not enough rights to change username"));
+      }
+
+      if (username == c->username) {
+        return promise.set_value(CheckDialogUsernameResult::Ok);
+      }
+      break;
+    }
+    case DialogType::None:
+      break;
+    case DialogType::Chat:
+    case DialogType::SecretChat:
+      if (username.empty()) {
+        return promise.set_value(CheckDialogUsernameResult::Ok);
+      }
+      return promise.set_error(Status::Error(3, "Chat can't have username"));
+    default:
+      UNREACHABLE();
+      return;
+  }
+
+  if (username.empty()) {
+    return promise.set_value(CheckDialogUsernameResult::Ok);
+  }
+  if (!is_valid_username(username)) {
+    return promise.set_value(CheckDialogUsernameResult::Invalid);
+  }
+
+  auto request_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<bool> result) mutable {
+    if (result.is_error()) {
+      auto error = result.move_as_error();
+      if (error.message() == "CHANNEL_PUBLIC_GROUP_NA") {
+        return promise.set_value(CheckDialogUsernameResult::PublicGroupsUnavailable);
+      }
+      if (error.message() == "CHANNELS_ADMIN_PUBLIC_TOO_MUCH") {
+        return promise.set_value(CheckDialogUsernameResult::PublicDialogsTooMuch);
+      }
+      if (error.message() == "USERNAME_INVALID") {
+        return promise.set_value(CheckDialogUsernameResult::Invalid);
+      }
+      promise.set_error(std::move(error));
+    }
+
+    promise.set_value(result.ok() ? CheckDialogUsernameResult::Ok : CheckDialogUsernameResult::Occupied);
+  });
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      return td_->create_handler<CheckUsernameQuery>(std::move(request_promise))->send(username);
+    case DialogType::Channel:
+      return td_->create_handler<CheckChannelUsernameQuery>(std::move(request_promise))
+          ->send(dialog_id.get_channel_id(), username);
+    case DialogType::None:
+      return td_->create_handler<CheckChannelUsernameQuery>(std::move(request_promise))->send(ChannelId(), username);
+    case DialogType::Chat:
+    case DialogType::SecretChat:
+    default:
+      UNREACHABLE();
+  }
+}
+
+td_api::object_ptr<td_api::CheckChatUsernameResult> ContactsManager::get_check_chat_username_result_object(
+    CheckDialogUsernameResult result) {
+  switch (result) {
+    case CheckDialogUsernameResult::Ok:
+      return td_api::make_object<td_api::checkChatUsernameResultOk>();
+    case CheckDialogUsernameResult::Invalid:
+      return td_api::make_object<td_api::checkChatUsernameResultUsernameInvalid>();
+    case CheckDialogUsernameResult::Occupied:
+      return td_api::make_object<td_api::checkChatUsernameResultUsernameOccupied>();
+    case CheckDialogUsernameResult::PublicDialogsTooMuch:
+      return td_api::make_object<td_api::checkChatUsernameResultPublicChatsTooMuch>();
+    case CheckDialogUsernameResult::PublicGroupsUnavailable:
+      return td_api::make_object<td_api::checkChatUsernameResultPublicGroupsUnavailable>();
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+void ContactsManager::set_account_ttl(int32 account_ttl, Promise<Unit> &&promise) const {
+  td_->create_handler<SetAccountTtlQuery>(std::move(promise))->send(account_ttl);
+}
+
+void ContactsManager::get_account_ttl(Promise<int32> &&promise) const {
+  td_->create_handler<GetAccountTtlQuery>(std::move(promise))->send();
+}
+
+void ContactsManager::get_active_sessions(Promise<tl_object_ptr<td_api::sessions>> &&promise) const {
+  td_->create_handler<GetAuthorizationsQuery>(std::move(promise))->send();
+}
+
+void ContactsManager::terminate_session(int64 session_id, Promise<Unit> &&promise) const {
+  td_->create_handler<ResetAuthorizationQuery>(std::move(promise))->send(session_id);
+}
+
+void ContactsManager::terminate_all_other_sessions(Promise<Unit> &&promise) const {
+  td_->create_handler<ResetAuthorizationsQuery>(std::move(promise))->send();
+}
+
+void ContactsManager::get_connected_websites(Promise<tl_object_ptr<td_api::connectedWebsites>> &&promise) const {
+  td_->create_handler<GetWebAuthorizationsQuery>(std::move(promise))->send();
+}
+
+void ContactsManager::disconnect_website(int64 website_id, Promise<Unit> &&promise) const {
+  td_->create_handler<ResetWebAuthorizationQuery>(std::move(promise))->send(website_id);
+}
+
+void ContactsManager::disconnect_all_websites(Promise<Unit> &&promise) const {
+  td_->create_handler<ResetWebAuthorizationsQuery>(std::move(promise))->send();
+}
+
+Status ContactsManager::block_user(UserId user_id) {
+  if (user_id == get_my_id("block_user")) {
+    return Status::Error(5, "Can't block self");
+  }
+
+  auto user = get_input_user(user_id);
+  if (user == nullptr) {
+    return Status::Error(5, "User not found");
+  }
+
+  td_->create_handler<BlockUserQuery>()->send(std::move(user));
+
+  on_update_user_blocked(user_id, true);
+  return Status::OK();
+}
+
+Status ContactsManager::unblock_user(UserId user_id) {
+  if (user_id == get_my_id("unblock_user")) {
+    return Status::Error(5, "Can't unblock self");
+  }
+
+  auto user = get_input_user(user_id);
+  if (user == nullptr) {
+    return Status::Error(5, "User not found");
+  }
+
+  td_->create_handler<UnblockUserQuery>()->send(std::move(user));
+
+  on_update_user_blocked(user_id, false);
+  return Status::OK();
+}
+
+bool ContactsManager::is_valid_username(const string &username) {
+  if (username.size() < 5 || username.size() > 32) {
+    return false;
+  }
+  if (!is_alpha(username[0])) {
+    return false;
+  }
+  for (auto c : username) {
+    if (!is_alpha(c) && !is_digit(c) && c != '_') {
+      return false;
+    }
+  }
+  if (username.back() == '_') {
+    return false;
+  }
+  for (size_t i = 1; i < username.size(); i++) {
+    if (username[i - 1] == '_' && username[i] == '_') {
+      return false;
+    }
+  }
+  if (username.find("admin") == 0 || username.find("telegram") == 0 || username.find("support") == 0 ||
+      username.find("security") == 0 || username.find("settings") == 0 || username.find("contacts") == 0 ||
+      username.find("service") == 0 || username.find("telegraph") == 0) {
+    return false;
+  }
+  return true;
+}
+
+int64 ContactsManager::get_blocked_users(int32 offset, int32 limit, Promise<Unit> &&promise) {
+  LOG(INFO) << "Get blocked users with offset = " << offset << " and limit = " << limit;
+
+  if (offset < 0) {
+    promise.set_error(Status::Error(3, "Parameter offset must be non-negative"));
+    return 0;
+  }
+
+  if (limit <= 0) {
+    promise.set_error(Status::Error(3, "Parameter limit must be positive"));
+    return 0;
+  }
+
+  int64 random_id;
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 || found_blocked_users_.find(random_id) != found_blocked_users_.end());
+  found_blocked_users_[random_id];  // reserve place for result
+
+  td_->create_handler<GetBlockedUsersQuery>(std::move(promise))->send(offset, limit, random_id);
+  return random_id;
+}
+
+void ContactsManager::on_get_blocked_users_result(int32 offset, int32 limit, int64 random_id, int32 total_count,
+                                                  vector<tl_object_ptr<telegram_api::contactBlocked>> &&blocked_users) {
+  LOG(INFO) << "Receive " << blocked_users.size() << " blocked users out of " << total_count;
+  auto it = found_blocked_users_.find(random_id);
+  CHECK(it != found_blocked_users_.end());
+
+  auto &result = it->second.second;
+  CHECK(result.empty());
+  for (auto &blocked_user : blocked_users) {
+    CHECK(blocked_user != nullptr);
+    UserId user_id(blocked_user->user_id_);
+    if (have_user(user_id)) {
+      result.push_back(user_id);
+    } else {
+      LOG(ERROR) << "Have no info about " << user_id;
+    }
+  }
+  it->second.first = total_count;
+}
+
+void ContactsManager::on_failed_get_blocked_users(int64 random_id) {
+  auto it = found_blocked_users_.find(random_id);
+  CHECK(it != found_blocked_users_.end());
+  found_blocked_users_.erase(it);
+}
+
+tl_object_ptr<td_api::users> ContactsManager::get_blocked_users_object(int64 random_id) {
+  auto it = found_blocked_users_.find(random_id);
+  CHECK(it != found_blocked_users_.end());
+  auto result = get_users_object(it->second.first, it->second.second);
+  found_blocked_users_.erase(it);
+  return result;
+}
+
+void ContactsManager::load_contacts(Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    are_contacts_loaded_ = true;
+    saved_contact_count_ = 0;
+  }
+  if (are_contacts_loaded_ && saved_contact_count_ != -1) {
+    LOG(INFO) << "Contacts are already loaded";
+    promise.set_value(Unit());
+    return;
+  }
+  load_contacts_queries_.push_back(std::move(promise));
+  if (load_contacts_queries_.size() == 1u) {
+    if (G()->parameters().use_chat_info_db && next_contacts_sync_date_ > 0 && saved_contact_count_ != -1) {
+      LOG(INFO) << "Load contacts from database";
+      G()->td_db()->get_sqlite_pmc()->get(
+          "user_contacts", PromiseCreator::lambda([](string value) {
+            send_closure(G()->contacts_manager(), &ContactsManager::on_load_contacts_from_database, std::move(value));
+          }));
+    } else {
+      LOG(INFO) << "Load contacts from server";
+      reload_contacts(true);
+    }
+  } else {
+    LOG(INFO) << "Load contacts request has already been sent";
+  }
+}
+
+int32 ContactsManager::get_contacts_hash() {
+  if (!are_contacts_loaded_) {
+    return 0;
+  }
+
+  vector<int64> user_ids = contacts_hints_.search_empty(100000).second;
+  CHECK(std::is_sorted(user_ids.begin(), user_ids.end()));
+  auto my_id = get_my_id("get_contacts_hash");
+  const User *u = get_user_force(my_id);
+  if (u != nullptr && u->outbound == LinkState::Contact) {
+    user_ids.insert(std::upper_bound(user_ids.begin(), user_ids.end(), my_id.get()), my_id.get());
+  }
+
+  vector<uint32> numbers;
+  numbers.reserve(user_ids.size() + 1);
+  numbers.push_back(saved_contact_count_);
+  for (auto user_id : user_ids) {
+    numbers.push_back(narrow_cast<uint32>(user_id));
+  }
+  return get_vector_hash(numbers);
+}
+
+void ContactsManager::reload_contacts(bool force) {
+  if (!td_->auth_manager_->is_bot() && next_contacts_sync_date_ != std::numeric_limits<int32>::max() &&
+      (next_contacts_sync_date_ < G()->unix_time() || force)) {
+    next_contacts_sync_date_ = std::numeric_limits<int32>::max();
+    td_->create_handler<GetContactsQuery>()->send(get_contacts_hash());
+  }
+}
+
+std::pair<vector<UserId>, vector<int32>> ContactsManager::import_contacts(
+    const vector<tl_object_ptr<td_api::contact>> &contacts, int64 &random_id, Promise<Unit> &&promise) {
+  if (!are_contacts_loaded_) {
+    load_contacts(std::move(promise));
+    return {};
+  }
+
+  LOG(INFO) << "Asked to import " << contacts.size() << " contacts with random_id = " << random_id;
+  if (random_id != 0) {
+    // request has already been sent before
+    auto it = imported_contacts_.find(random_id);
+    CHECK(it != imported_contacts_.end());
+    auto result = std::move(it->second);
+    imported_contacts_.erase(it);
+
+    promise.set_value(Unit());
+    return result;
+  }
+  for (auto &contact : contacts) {
+    if (contact == nullptr) {
+      promise.set_error(Status::Error(400, "Imported contacts should not be empty"));
+      return {};
+    }
+  }
+
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 || imported_contacts_.find(random_id) != imported_contacts_.end());
+  imported_contacts_[random_id];  // reserve place for result
+
+  td_->create_handler<ImportContactsQuery>(std::move(promise))
+      ->send(transform(contacts,
+                       [](const tl_object_ptr<td_api::contact> &contact) {
+                         return Contact(contact->phone_number_, contact->first_name_, contact->last_name_, 0);
+                       }),
+             random_id);
+  return {};
+}
+
+void ContactsManager::remove_contacts(vector<UserId> user_ids, Promise<Unit> &&promise) {
+  LOG(INFO) << "Delete contacts: " << format::as_array(user_ids);
+  if (!are_contacts_loaded_) {
+    load_contacts(std::move(promise));
+    return;
+  }
+
+  vector<UserId> to_delete_user_ids;
+  vector<tl_object_ptr<telegram_api::InputUser>> input_users;
+  for (auto &user_id : user_ids) {
+    const User *u = get_user(user_id);
+    if (u != nullptr && u->outbound == LinkState::Contact) {
+      auto input_user = get_input_user(user_id);
+      if (input_user != nullptr) {
+        to_delete_user_ids.push_back(user_id);
+        input_users.push_back(std::move(input_user));
+      }
+    }
+  }
+
+  if (input_users.empty()) {
+    return promise.set_value(Unit());
+  }
+
+  // TODO DeleteContactQuery
+  td_->create_handler<DeleteContactsQuery>(std::move(promise))
+      ->send(std::move(to_delete_user_ids), std::move(input_users));
+}
+
+int32 ContactsManager::get_imported_contact_count(Promise<Unit> &&promise) {
+  LOG(INFO) << "Get imported contact count";
+
+  if (!are_contacts_loaded_ || saved_contact_count_ == -1) {
+    load_contacts(std::move(promise));
+    return 0;
+  }
+  reload_contacts(false);
+
+  promise.set_value(Unit());
+  return saved_contact_count_ + static_cast<int32>(contacts_hints_.size());
+}
+
+void ContactsManager::load_imported_contacts(Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    are_imported_contacts_loaded_ = true;
+  }
+  if (are_imported_contacts_loaded_) {
+    LOG(INFO) << "Imported contacts are already loaded";
+    promise.set_value(Unit());
+    return;
+  }
+  load_imported_contacts_queries_.push_back(std::move(promise));
+  if (load_imported_contacts_queries_.size() == 1u) {
+    if (G()->parameters().use_chat_info_db) {
+      LOG(INFO) << "Load imported contacts from database";
+      G()->td_db()->get_sqlite_pmc()->get(
+          "user_imported_contacts", PromiseCreator::lambda([](string value) {
+            send_closure_later(G()->contacts_manager(), &ContactsManager::on_load_imported_contacts_from_database,
+                               std::move(value));
+          }));
+    } else {
+      LOG(INFO) << "Have no previously imported contacts";
+      send_closure_later(G()->contacts_manager(), &ContactsManager::on_load_imported_contacts_from_database, string());
+    }
+  } else {
+    LOG(INFO) << "Load imported contacts request has already been sent";
+  }
+}
+
+void ContactsManager::on_load_imported_contacts_from_database(string value) {
+  CHECK(!are_imported_contacts_loaded_);
+  if (value.empty()) {
+    CHECK(all_imported_contacts_.empty());
+  } else {
+    log_event_parse(all_imported_contacts_, value).ensure();
+    LOG(INFO) << "Successfully loaded " << all_imported_contacts_.size() << " imported contacts from database";
+  }
+
+  load_imported_contact_users_multipromise_.add_promise(PromiseCreator::lambda([](Result<> result) {
+    if (result.is_ok()) {
+      send_closure_later(G()->contacts_manager(), &ContactsManager::on_load_imported_contacts_finished);
+    }
+  }));
+
+  auto lock_promise = load_imported_contact_users_multipromise_.get_promise();
+
+  for (const auto &contact : all_imported_contacts_) {
+    auto user_id = contact.get_user_id();
+    if (user_id.is_valid()) {
+      get_user(user_id, 3, load_imported_contact_users_multipromise_.get_promise());
+    }
+  }
+
+  lock_promise.set_value(Unit());
+}
+
+void ContactsManager::on_load_imported_contacts_finished() {
+  LOG(INFO) << "Finished to load " << all_imported_contacts_.size() << " imported contacts";
+
+  for (const auto &contact : all_imported_contacts_) {
+    get_user_id_object(contact.get_user_id(), "on_load_imported_contacts_finished");  // to ensure updateUser
+  }
+
+  are_imported_contacts_loaded_ = true;
+  auto promises = std::move(load_imported_contacts_queries_);
+  load_imported_contacts_queries_.clear();
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+std::pair<vector<UserId>, vector<int32>> ContactsManager::change_imported_contacts(
+    vector<tl_object_ptr<td_api::contact>> &&contacts, int64 &random_id, Promise<Unit> &&promise) {
+  if (!are_contacts_loaded_) {
+    load_contacts(std::move(promise));
+    return {};
+  }
+  if (!are_imported_contacts_loaded_) {
+    load_imported_contacts(std::move(promise));
+    return {};
+  }
+
+  LOG(INFO) << "Asked to change imported contacts to a list of " << contacts.size()
+            << " contacts with random_id = " << random_id;
+  if (random_id != 0) {
+    // request has already been sent before
+    CHECK(are_imported_contacts_changing_);
+    are_imported_contacts_changing_ = false;
+
+    auto unimported_contact_invites = std::move(unimported_contact_invites_);
+    unimported_contact_invites_.clear();
+
+    auto imported_contact_user_ids = std::move(imported_contact_user_ids_);
+    imported_contact_user_ids_.clear();
+
+    promise.set_value(Unit());
+    return {std::move(imported_contact_user_ids), std::move(unimported_contact_invites)};
+  }
+
+  if (are_imported_contacts_changing_) {
+    promise.set_error(Status::Error(400, "ChangeImportedContacts can be called only once at the same time"));
+    return {};
+  }
+
+  for (auto &contact : contacts) {
+    if (contact == nullptr) {
+      promise.set_error(Status::Error(400, "Contacts should not be empty"));
+      return {};
+    }
+  }
+
+  auto new_contacts = transform(std::move(contacts), [](tl_object_ptr<td_api::contact> &&contact) {
+    return Contact(std::move(contact->phone_number_), std::move(contact->first_name_), std::move(contact->last_name_),
+                   0);
+  });
+
+  vector<size_t> new_contacts_unique_id(new_contacts.size());
+  vector<Contact> unique_new_contacts;
+  unique_new_contacts.reserve(new_contacts.size());
+  std::unordered_map<Contact, size_t, ContactHash, ContactEqual> different_new_contacts;
+  std::unordered_set<string> different_new_phone_numbers;
+  size_t unique_size = 0;
+  for (size_t i = 0; i < new_contacts.size(); i++) {
+    auto it_success = different_new_contacts.emplace(std::move(new_contacts[i]), unique_size);
+    new_contacts_unique_id[i] = it_success.first->second;
+    if (it_success.second) {
+      unique_new_contacts.push_back(it_success.first->first);
+      different_new_phone_numbers.insert(unique_new_contacts.back().get_phone_number());
+      unique_size++;
+    }
+  }
+
+  vector<UserId> to_delete;
+  for (auto &old_contact : all_imported_contacts_) {
+    auto user_id = old_contact.get_user_id();
+    auto it = different_new_contacts.find(old_contact);
+    if (it == different_new_contacts.end()) {
+      if (user_id.is_valid() && different_new_phone_numbers.count(old_contact.get_phone_number()) == 0) {
+        to_delete.push_back(user_id);
+      }
+    } else {
+      unique_new_contacts[it->second].set_user_id(user_id);
+      different_new_contacts.erase(it);
+    }
+  }
+  std::pair<vector<size_t>, vector<Contact>> to_add;
+  for (auto &new_contact : different_new_contacts) {
+    to_add.first.push_back(new_contact.second);
+    to_add.second.push_back(std::move(new_contact.first));
+  }
+
+  if (to_add.first.empty() && to_delete.empty()) {
+    for (size_t i = 0; i < new_contacts.size(); i++) {
+      auto unique_id = new_contacts_unique_id[i];
+      new_contacts[i].set_user_id(unique_new_contacts[unique_id].get_user_id());
+    }
+
+    promise.set_value(Unit());
+    return {transform(new_contacts, [&](const Contact &contact) { return contact.get_user_id(); }),
+            vector<int32>(new_contacts.size())};
+  }
+
+  are_imported_contacts_changing_ = true;
+  random_id = 1;
+
+  remove_contacts(
+      std::move(to_delete),
+      PromiseCreator::lambda([new_contacts = std::move(unique_new_contacts),
+                              new_contacts_unique_id = std::move(new_contacts_unique_id), to_add = std::move(to_add),
+                              promise = std::move(promise)](Result<> result) mutable {
+        if (result.is_ok()) {
+          send_closure_later(G()->contacts_manager(), &ContactsManager::on_clear_imported_contacts,
+                             std::move(new_contacts), std::move(new_contacts_unique_id), std::move(to_add),
+                             std::move(promise));
+        } else {
+          promise.set_error(result.move_as_error());
+        }
+      }));
+  return {};
+}
+
+void ContactsManager::on_clear_imported_contacts(vector<Contact> &&contacts, vector<size_t> contacts_unique_id,
+                                                 std::pair<vector<size_t>, vector<Contact>> &&to_add,
+                                                 Promise<Unit> &&promise) {
+  LOG(INFO) << "Add " << to_add.first.size() << " contacts";
+  next_all_imported_contacts_ = std::move(contacts);
+  imported_contacts_unique_id_ = std::move(contacts_unique_id);
+  imported_contacts_pos_ = std::move(to_add.first);
+
+  td_->create_handler<ImportContactsQuery>(std::move(promise))->send(std::move(to_add.second), 0);
+}
+
+void ContactsManager::clear_imported_contacts(Promise<Unit> &&promise) {
+  LOG(INFO) << "Delete imported contacts";
+
+  if (!are_contacts_loaded_ || saved_contact_count_ == -1) {
+    load_contacts(std::move(promise));
+    return;
+  }
+
+  if (contacts_hints_.size() == 0 && saved_contact_count_ == 0) {
+    promise.set_value(Unit());
+    return;
+  }
+
+  td_->create_handler<ResetContactsQuery>(std::move(promise))->send();
+}
+
+void ContactsManager::on_update_contacts_reset() {
+  UserId my_id = get_my_id("on_update_contacts_reset");
+  for (auto &p : users_) {
+    UserId user_id = p.first;
+    User &u = p.second;
+    bool is_contact = u.outbound == LinkState::Contact;
+    if (is_contact) {
+      LOG(INFO) << "Drop contact with " << user_id;
+      if (user_id != my_id) {
+        CHECK(contacts_hints_.has_key(user_id.get()));
+      }
+      on_update_user_links(&u, user_id, LinkState::KnowsPhoneNumber, u.inbound);
+      update_user(&u, user_id);
+      CHECK(u.outbound != LinkState::Contact);
+      if (user_id != my_id) {
+        CHECK(!contacts_hints_.has_key(user_id.get()));
+      }
+    }
+  }
+
+  saved_contact_count_ = 0;
+  reload_contacts(true);
+}
+
+std::pair<int32, vector<UserId>> ContactsManager::search_contacts(const string &query, int32 limit,
+                                                                  Promise<Unit> &&promise) {
+  LOG(INFO) << "Search contacts with query = \"" << query << "\" and limit = " << limit;
+
+  if (limit < 0) {
+    promise.set_error(Status::Error(400, "Limit must be non-negative"));
+    return {};
+  }
+
+  if (!are_contacts_loaded_) {
+    load_contacts(std::move(promise));
+    return {};
+  }
+  reload_contacts(false);
+
+  std::pair<size_t, vector<int64>> result;
+  if (query.empty()) {
+    result = contacts_hints_.search_empty(limit);
+  } else {
+    result = contacts_hints_.search(query, limit);
+  }
+
+  vector<UserId> user_ids;
+  user_ids.reserve(result.second.size());
+  for (auto key : result.second) {
+    user_ids.emplace_back(narrow_cast<int32>(key));
+  }
+
+  promise.set_value(Unit());
+  return {narrow_cast<int32>(result.first), std::move(user_ids)};
+}
+
+void ContactsManager::set_profile_photo(const tl_object_ptr<td_api::InputFile> &input_photo, Promise<Unit> &&promise) {
+  auto r_file_id = td_->file_manager_->get_input_file_id(FileType::Photo, input_photo,
+                                                         DialogId(get_my_id("set_profile_photo")), false, false);
+  if (r_file_id.is_error()) {
+    // TODO promise.set_error(std::move(status));
+    return promise.set_error(Status::Error(7, r_file_id.error().message()));
+  }
+  FileId file_id = r_file_id.ok();
+  CHECK(file_id.is_valid());
+
+  FileView file_view = td_->file_manager_->get_file_view(file_id);
+  CHECK(!file_view.is_encrypted());
+  if (file_view.has_remote_location() && !file_view.remote_location().is_web()) {
+    td_->create_handler<UpdateProfilePhotoQuery>(std::move(promise))
+        ->send(file_view.remote_location().as_input_photo());
+    return;
+  }
+
+  auto upload_file_id = td_->file_manager_->dup_file_id(file_id);
+  CHECK(upload_file_id.is_valid());
+  CHECK(uploaded_profile_photos_.find(upload_file_id) == uploaded_profile_photos_.end());
+  uploaded_profile_photos_.emplace(upload_file_id, std::move(promise));
+  LOG(INFO) << "Ask to upload profile photo " << upload_file_id;
+  td_->file_manager_->upload(upload_file_id, upload_profile_photo_callback_, 1, 0);
+}
+
+void ContactsManager::delete_profile_photo(int64 profile_photo_id, Promise<Unit> &&promise) {
+  const User *u = get_user(get_my_id("delete_profile_photo"));
+  if (u != nullptr && u->photo.id == profile_photo_id) {
+    td_->create_handler<UpdateProfilePhotoQuery>(std::move(promise))
+        ->send(make_tl_object<telegram_api::inputPhotoEmpty>());
+    return;
+  }
+
+  td_->create_handler<DeleteProfilePhotoQuery>(std::move(promise))->send(profile_photo_id);
+}
+
+void ContactsManager::set_name(const string &first_name, const string &last_name, Promise<Unit> &&promise) {
+  auto new_first_name = clean_name(first_name, MAX_NAME_LENGTH);
+  auto new_last_name = clean_name(last_name, MAX_NAME_LENGTH);
+  if (new_first_name.empty()) {
+    return promise.set_error(Status::Error(7, "First name must be non-empty"));
+  }
+
+  const User *u = get_user(get_my_id("set_name"));
+  int32 flags = 0;
+  // TODO we can already send request for changing first_name and last_name and wanting to set initial values
+  // TODO need to be rewritten using invoke after and cancelling previous request
+  if (u == nullptr || u->first_name != new_first_name) {
+    flags |= ACCOUNT_UPDATE_FIRST_NAME;
+  }
+  if (u == nullptr || u->last_name != new_last_name) {
+    flags |= ACCOUNT_UPDATE_LAST_NAME;
+  }
+  if (flags == 0) {
+    return promise.set_value(Unit());
+  }
+
+  td_->create_handler<UpdateProfileQuery>(std::move(promise))->send(flags, new_first_name, new_last_name, "");
+}
+
+void ContactsManager::set_bio(const string &bio, Promise<Unit> &&promise) {
+  auto new_bio = strip_empty_characters(bio, MAX_BIO_LENGTH);
+  for (auto &c : new_bio) {
+    if (c == '\n') {
+      c = ' ';
+    }
+  }
+
+  const UserFull *user_full = get_user_full(get_my_id("set_bio"));
+  int32 flags = 0;
+  // TODO we can already send request for changing bio and wanting to set initial values
+  // TODO need to be rewritten using invoke after and cancelling previous request
+  if (user_full == nullptr || user_full->about != new_bio) {
+    flags |= ACCOUNT_UPDATE_ABOUT;
+  }
+  if (flags == 0) {
+    return promise.set_value(Unit());
+  }
+
+  td_->create_handler<UpdateProfileQuery>(std::move(promise))->send(flags, "", "", new_bio);
+}
+
+void ContactsManager::on_update_profile_success(int32 flags, const string &first_name, const string &last_name,
+                                                const string &about) {
+  CHECK(flags != 0);
+
+  auto my_user_id = get_my_id("on_update_profile_success");
+  const User *u = get_user(my_user_id);
+  if (u == nullptr) {
+    LOG(ERROR) << "Doesn't receive info about me during update profile";
+    return;
+  }
+  LOG_IF(ERROR, (flags & ACCOUNT_UPDATE_FIRST_NAME) != 0 && u->first_name != first_name)
+      << "Wrong first name \"" << u->first_name << "\", expected \"" << first_name << '"';
+  LOG_IF(ERROR, (flags & ACCOUNT_UPDATE_LAST_NAME) != 0 && u->last_name != last_name)
+      << "Wrong last name \"" << u->last_name << "\", expected \"" << last_name << '"';
+
+  if ((flags & ACCOUNT_UPDATE_ABOUT) != 0) {
+    UserFull *user_full = get_user_full(my_user_id);
+    if (user_full != nullptr && user_full->is_inited) {
+      user_full->about = about;
+      user_full->is_changed = true;
+      update_user_full(user_full, my_user_id);
+    }
+  }
+}
+
+void ContactsManager::set_username(const string &username, Promise<Unit> &&promise) {
+  if (!username.empty() && !is_valid_username(username)) {
+    return promise.set_error(Status::Error(400, "Username is invalid"));
+  }
+  td_->create_handler<UpdateUsernameQuery>(std::move(promise))->send(username);
+}
+
+void ContactsManager::toggle_chat_administrators(ChatId chat_id, bool everyone_is_administrator,
+                                                 Promise<Unit> &&promise) {
+  auto c = get_chat(chat_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(6, "Group not found"));
+  }
+  if (!get_chat_status(c).is_creator()) {
+    return promise.set_error(Status::Error(6, "Not enough rights to toggle basic group administrators"));
+  }
+
+  td_->create_handler<ToggleChatAdminsQuery>(std::move(promise))->send(chat_id, everyone_is_administrator);
+}
+
+void ContactsManager::set_channel_username(ChannelId channel_id, const string &username, Promise<Unit> &&promise) {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(6, "Supergroup not found"));
+  }
+  if (!get_channel_status(c).is_creator()) {
+    return promise.set_error(Status::Error(6, "Not enough rights to change supergroup username"));
+  }
+
+  if (!username.empty() && !is_valid_username(username)) {
+    return promise.set_error(Status::Error(400, "Username is invalid"));
+  }
+
+  if (!username.empty() && c->username.empty()) {
+    auto channel_full = get_channel_full(channel_id);
+    if (channel_full != nullptr && !channel_full->can_set_username) {
+      return promise.set_error(Status::Error(3, "Can't set supergroup username"));
+    }
+  }
+
+  td_->create_handler<UpdateChannelUsernameQuery>(std::move(promise))->send(channel_id, username);
+}
+
+void ContactsManager::set_channel_sticker_set(ChannelId channel_id, int64 sticker_set_id, Promise<Unit> &&promise) {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(6, "Supergroup not found"));
+  }
+  if (!c->is_megagroup) {
+    return promise.set_error(Status::Error(6, "Chat sticker set can be set only for supergroups"));
+  }
+  if (!get_channel_status(c).can_change_info_and_settings()) {
+    return promise.set_error(Status::Error(6, "Not enough rights to change supergroup sticker set"));
+  }
+
+  telegram_api::object_ptr<telegram_api::InputStickerSet> input_sticker_set;
+  if (sticker_set_id == 0) {
+    input_sticker_set = telegram_api::make_object<telegram_api::inputStickerSetEmpty>();
+  } else {
+    input_sticker_set = td_->stickers_manager_->get_input_sticker_set(sticker_set_id);
+    if (input_sticker_set == nullptr) {
+      return promise.set_error(Status::Error(3, "Sticker set not found"));
+    }
+  }
+
+  auto channel_full = get_channel_full(channel_id);
+  if (channel_full != nullptr && !channel_full->can_set_sticker_set) {
+    return promise.set_error(Status::Error(3, "Can't set supergroup sticker set"));
+  }
+
+  td_->create_handler<SetChannelStickerSetQuery>(std::move(promise))
+      ->send(channel_id, sticker_set_id, std::move(input_sticker_set));
+}
+
+void ContactsManager::toggle_channel_invites(ChannelId channel_id, bool anyone_can_invite, Promise<Unit> &&promise) {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(6, "Supergroup not found"));
+  }
+  if (!get_channel_status(c).can_change_info_and_settings()) {
+    return promise.set_error(Status::Error(6, "Not enough rights to toggle supergroup invites"));
+  }
+  if (get_channel_type(c) != ChannelType::Megagroup) {
+    return promise.set_error(Status::Error(6, "Invites by any member can be enabled in the supergroups only"));
+  }
+
+  td_->create_handler<ToggleChannelInvitesQuery>(std::move(promise))->send(channel_id, anyone_can_invite);
+}
+
+void ContactsManager::toggle_channel_sign_messages(ChannelId channel_id, bool sign_messages, Promise<Unit> &&promise) {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(6, "Supergroup not found"));
+  }
+  if (get_channel_type(c) == ChannelType::Megagroup) {
+    return promise.set_error(Status::Error(6, "Message signatures can't be toggled in supergroups"));
+  }
+  if (!get_channel_status(c).can_change_info_and_settings()) {
+    return promise.set_error(Status::Error(6, "Not enough rights to toggle channel sign messages"));
+  }
+
+  td_->create_handler<ToggleChannelSignaturesQuery>(std::move(promise))->send(channel_id, sign_messages);
+}
+
+void ContactsManager::toggle_channel_is_all_history_available(ChannelId channel_id, bool is_all_history_available,
+                                                              Promise<Unit> &&promise) {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(6, "Supergroup not found"));
+  }
+  if (!get_channel_status(c).can_change_info_and_settings()) {
+    return promise.set_error(Status::Error(6, "Not enough rights to toggle all supergroup history availability"));
+  }
+  if (get_channel_type(c) != ChannelType::Megagroup) {
+    return promise.set_error(Status::Error(6, "Message history can be hidden in the supergroups only"));
+  }
+
+  td_->create_handler<ToggleChannelIsAllHistoryAvailableQuery>(std::move(promise))
+      ->send(channel_id, is_all_history_available);
+}
+
+void ContactsManager::set_channel_description(ChannelId channel_id, const string &description,
+                                              Promise<Unit> &&promise) {
+  auto new_description = strip_empty_characters(description, MAX_NAME_LENGTH);
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(6, "Supergroup not found"));
+  }
+  if (!get_channel_status(c).can_change_info_and_settings()) {
+    return promise.set_error(Status::Error(6, "Not enough rights to set supergroup description"));
+  }
+
+  td_->create_handler<EditChannelAboutQuery>(std::move(promise))->send(channel_id, new_description);
+}
+
+void ContactsManager::pin_channel_message(ChannelId channel_id, MessageId message_id, bool disable_notification,
+                                          Promise<Unit> &&promise) {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(6, "Supergroup not found"));
+  }
+  auto channel_status = get_channel_status(c);
+  bool can_pin = c->is_megagroup ? channel_status.can_pin_messages() : channel_status.can_edit_messages();
+  if (!can_pin) {
+    return promise.set_error(Status::Error(6, "Not enough rights to pin a message"));
+  }
+
+  if (!td_->messages_manager_->have_message({DialogId(channel_id), message_id})) {
+    return promise.set_error(Status::Error(6, "Message not found"));
+  }
+
+  if (!message_id.is_server()) {
+    return promise.set_error(Status::Error(6, "Message can't be pinned"));
+  }
+
+  td_->create_handler<UpdateChannelPinnedMessageQuery>(std::move(promise))
+      ->send(channel_id, message_id, disable_notification);
+}
+
+void ContactsManager::unpin_channel_message(ChannelId channel_id, Promise<Unit> &&promise) {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(6, "Supergroup not found"));
+  }
+  auto channel_status = get_channel_status(c);
+  bool can_unpin = c->is_megagroup ? channel_status.can_pin_messages() : channel_status.can_edit_messages();
+  if (!can_unpin) {
+    return promise.set_error(Status::Error(6, "Not enough rights to unpin a message"));
+  }
+
+  td_->create_handler<UpdateChannelPinnedMessageQuery>(std::move(promise))->send(channel_id, MessageId(), false);
+}
+
+void ContactsManager::report_channel_spam(ChannelId channel_id, UserId user_id, const vector<MessageId> &message_ids,
+                                          Promise<Unit> &&promise) {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(6, "Supergroup not found"));
+  }
+  if (!c->is_megagroup) {
+    return promise.set_error(Status::Error(6, "Spam can be reported only in supergroups"));
+  }
+
+  if (!have_input_user(user_id)) {
+    return promise.set_error(Status::Error(6, "Have no access to the user"));
+  }
+  if (user_id == get_my_id("report_channel_spam")) {
+    return promise.set_error(Status::Error(6, "Can't report self"));
+  }
+
+  if (message_ids.empty()) {
+    return promise.set_error(Status::Error(6, "Message list is empty"));
+  }
+
+  vector<MessageId> server_message_ids;
+  for (auto &message_id : message_ids) {
+    if (!message_id.is_valid()) {
+      return promise.set_error(Status::Error(6, "Message not found"));
+    }
+
+    if (message_id.is_server()) {
+      server_message_ids.push_back(message_id);
+    }
+  }
+  if (server_message_ids.empty()) {
+    return promise.set_value(Unit());
+  }
+
+  td_->create_handler<ReportChannelSpamQuery>(std::move(promise))->send(channel_id, user_id, server_message_ids);
+}
+
+void ContactsManager::delete_channel(ChannelId channel_id, Promise<Unit> &&promise) {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(6, "Supergroup not found"));
+  }
+  if (!get_channel_status(c).is_creator()) {
+    return promise.set_error(Status::Error(6, "Not enough rights to delete the supergroup"));
+  }
+
+  td_->create_handler<DeleteChannelQuery>(std::move(promise))->send(channel_id);
+}
+
+void ContactsManager::add_chat_participant(ChatId chat_id, UserId user_id, int32 forward_limit,
+                                           Promise<Unit> &&promise) {
+  const Chat *c = get_chat(chat_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(3, "Chat info not found"));
+  }
+  if (!c->is_active) {
+    return promise.set_error(Status::Error(3, "Chat is deactivated"));
+  }
+  if (forward_limit < 0) {
+    return promise.set_error(Status::Error(3, "Can't forward negative number of messages"));
+  }
+  if (user_id != get_my_id("add_chat_participant")) {
+    if (!get_chat_status(c).can_invite_users()) {
+      return promise.set_error(Status::Error(3, "Not enough rights to invite members to the group chat"));
+    }
+  } else if (c->kicked) {
+    return promise.set_error(Status::Error(3, "User was kicked from the chat"));
+  }
+  // TODO upper bound on forward_limit
+
+  auto input_user = get_input_user(user_id);
+  if (input_user == nullptr) {
+    return promise.set_error(Status::Error(3, "User not found"));
+  }
+
+  // TODO invoke after
+  td_->create_handler<AddChatUserQuery>(std::move(promise))->send(chat_id, std::move(input_user), forward_limit);
+}
+
+void ContactsManager::add_channel_participant(ChannelId channel_id, UserId user_id, Promise<Unit> &&promise,
+                                              DialogParticipantStatus old_status) {
+  if (td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(400, "Bots can't add new chat members"));
+  }
+
+  const Channel *c = get_channel(channel_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(3, "Chat info not found"));
+  }
+  auto input_user = get_input_user(user_id);
+  if (input_user == nullptr) {
+    return promise.set_error(Status::Error(3, "User not found"));
+  }
+
+  if (user_id == get_my_id("add_channel_participant")) {
+    // join the channel
+    if (get_channel_status(c).is_banned()) {
+      return promise.set_error(Status::Error(3, "Can't return to kicked from chat"));
+    }
+
+    td_->create_handler<JoinChannelQuery>(std::move(promise))->send(channel_id);
+    return;
+  }
+
+  if (!(c->anyone_can_invite && get_channel_status(c).is_member()) && !get_channel_status(c).can_invite_users()) {
+    return promise.set_error(Status::Error(3, "Not enough rights to invite members to the supergroup chat"));
+  }
+
+  speculative_add_channel_users(channel_id, DialogParticipantStatus::Member(), old_status);
+  vector<tl_object_ptr<telegram_api::InputUser>> input_users;
+  input_users.push_back(std::move(input_user));
+  td_->create_handler<InviteToChannelQuery>(std::move(promise))->send(channel_id, std::move(input_users));
+}
+
+void ContactsManager::add_channel_participants(ChannelId channel_id, const vector<UserId> &user_ids,
+                                               Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(400, "Bots can't add new chat members"));
+  }
+
+  const Channel *c = get_channel(channel_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(3, "Chat info not found"));
+  }
+
+  if (!(c->anyone_can_invite && get_channel_status(c).is_member()) && !get_channel_status(c).can_invite_users()) {
+    return promise.set_error(Status::Error(3, "Not enough rights to invite members to the supergroup chat"));
+  }
+
+  vector<tl_object_ptr<telegram_api::InputUser>> input_users;
+  for (auto user_id : user_ids) {
+    auto input_user = get_input_user(user_id);
+    if (input_user == nullptr) {
+      return promise.set_error(Status::Error(3, "User not found"));
+    }
+
+    if (user_id == get_my_id("add_channel_participants")) {
+      // can't invite self
+      continue;
+    }
+    input_users.push_back(std::move(input_user));
+  }
+
+  if (input_users.empty()) {
+    return promise.set_value(Unit());
+  }
+
+  td_->create_handler<InviteToChannelQuery>(std::move(promise))->send(channel_id, std::move(input_users));
+}
+
+void ContactsManager::change_channel_participant_status(ChannelId channel_id, UserId user_id,
+                                                        DialogParticipantStatus status, Promise<Unit> &&promise) {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(6, "Chat info not found"));
+  }
+
+  auto input_user = get_input_user(user_id);
+  if (input_user == nullptr) {
+    return promise.set_error(Status::Error(6, "User not found"));
+  }
+
+  if (user_id == get_my_id("change_channel_participant_status")) {
+    // fast path is needed, because get_channel_status may return Creator, while GetChannelParticipantQuery returning Left
+    return change_channel_participant_status_impl(channel_id, user_id, std::move(status), get_channel_status(c),
+                                                  std::move(promise));
+  }
+
+  auto on_result_promise =
+      PromiseCreator::lambda([actor_id = actor_id(this), channel_id, user_id, status,
+                              promise = std::move(promise)](Result<DialogParticipant> r_dialog_participant) mutable {
+        // ResultHandlers are cleared before managers, so it is safe to capture this
+        if (r_dialog_participant.is_error()) {
+          return promise.set_error(r_dialog_participant.move_as_error());
+        }
+
+        send_closure(actor_id, &ContactsManager::change_channel_participant_status_impl, channel_id, user_id,
+                     std::move(status), r_dialog_participant.ok().status, std::move(promise));
+      });
+
+  td_->create_handler<GetChannelParticipantQuery>(std::move(on_result_promise))
+      ->send(channel_id, user_id, std::move(input_user));
+}
+
+void ContactsManager::change_channel_participant_status_impl(ChannelId channel_id, UserId user_id,
+                                                             DialogParticipantStatus status,
+                                                             DialogParticipantStatus old_status,
+                                                             Promise<Unit> &&promise) {
+  if (old_status == status) {
+    return promise.set_value(Unit());
+  }
+
+  LOG(INFO) << "Change status of " << user_id << " in " << channel_id << " from " << old_status << " to " << status;
+  bool need_add = false;
+  bool need_promote = false;
+  bool need_restrict = false;
+  if (status.is_creator() || old_status.is_creator()) {
+    if (!old_status.is_creator()) {
+      return promise.set_error(Status::Error(3, "Can't add creator to the chat"));
+    }
+    if (status.is_member()) {
+      // creator member -> not creator member
+      // creator not member -> creator member
+      // creator not member -> not creator member
+      if (old_status.is_member()) {
+        return promise.set_error(Status::Error(3, "Can't demote chat creator"));
+      }
+      need_add = true;
+    } else {
+      // creator member -> creator not member
+      // creator member -> not creator not member
+      // creator not member -> not creator not member
+      if (!old_status.is_member()) {
+        return promise.set_error(Status::Error(3, "Can't restrict chat creator"));
+      }
+      need_restrict = true;
+    }
+  } else if (status.is_administrator()) {
+    need_promote = true;
+  } else if (!status.is_member() || status.is_restricted()) {
+    need_restrict = true;
+  } else {
+    // regular member
+    if (old_status.is_administrator()) {
+      need_promote = true;
+    } else if (old_status.is_restricted() || old_status.is_banned()) {
+      need_restrict = true;
+    } else {
+      CHECK(!old_status.is_member());
+      need_add = true;
+    }
+  }
+
+  if (need_promote) {
+    return promote_channel_participant(channel_id, user_id, std::move(status), std::move(old_status),
+                                       std::move(promise));
+  } else if (need_restrict) {
+    return restrict_channel_participant(channel_id, user_id, std::move(status), std::move(old_status),
+                                        std::move(promise));
+  } else {
+    CHECK(need_add);
+    return add_channel_participant(channel_id, user_id, std::move(promise), std::move(old_status));
+  }
+}
+
+void ContactsManager::promote_channel_participant(ChannelId channel_id, UserId user_id, DialogParticipantStatus status,
+                                                  DialogParticipantStatus old_status, Promise<Unit> &&promise) {
+  LOG(INFO) << "Promote " << user_id << " in " << channel_id << " from " << old_status << " to " << status;
+  const Channel *c = get_channel(channel_id);
+  CHECK(c != nullptr);
+
+  if (user_id == get_my_id("change_channel_participant_status")) {
+    if (status.is_administrator()) {
+      return promise.set_error(Status::Error(3, "Can't promote self"));
+    }
+    CHECK(status.is_member());
+    // allow to demote self. TODO is it allowed server-side?
+  } else {
+    if (!get_channel_status(c).can_promote_members()) {
+      return promise.set_error(Status::Error(3, "Not enough rights"));
+    }
+  }
+
+  auto input_user = get_input_user(user_id);
+  if (input_user == nullptr) {
+    return promise.set_error(Status::Error(3, "User not found"));
+  }
+
+  speculative_add_channel_users(channel_id, status, old_status);
+  td_->create_handler<EditChannelAdminQuery>(std::move(promise))->send(channel_id, std::move(input_user), status);
+}
+
+void ContactsManager::change_chat_participant_status(ChatId chat_id, UserId user_id, DialogParticipantStatus status,
+                                                     Promise<Unit> &&promise) {
+  if (!status.is_member()) {
+    return delete_chat_participant(chat_id, user_id, std::move(promise));
+  }
+
+  auto c = get_chat(chat_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(6, "Chat info not found"));
+  }
+
+  if (!get_chat_status(c).can_promote_members()) {
+    return promise.set_error(Status::Error(3, "Need creator rights in the group chat"));
+  }
+
+  if (c->everyone_is_administrator) {
+    return promise.set_error(Status::Error(3, "Administrators editing is disabled in the group chat"));
+  }
+
+  if (user_id == get_my_id("change_chat_participant_status")) {
+    return promise.set_error(Status::Error(3, "Can't change chat member status of self"));
+  }
+
+  auto input_user = get_input_user(user_id);
+  if (input_user == nullptr) {
+    return promise.set_error(Status::Error(3, "User not found"));
+  }
+
+  if (status.is_creator()) {
+    return promise.set_error(Status::Error(3, "Can't add creator to the group chat"));
+  }
+  if (status.is_restricted()) {
+    return promise.set_error(Status::Error(3, "Can't restrict users in a basic group chat"));
+  }
+
+  td_->create_handler<EditChatAdminQuery>(std::move(promise))
+      ->send(chat_id, std::move(input_user), status.is_administrator());
+}
+
+void ContactsManager::export_chat_invite_link(ChatId chat_id, Promise<Unit> &&promise) {
+  const Chat *c = get_chat(chat_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(3, "Chat info not found"));
+  }
+  if (!c->is_active) {
+    return promise.set_error(Status::Error(3, "Chat is deactivated"));
+  }
+
+  if (!get_chat_status(c).can_export_dialog_invite_link()) {
+    return promise.set_error(Status::Error(3, "Not enough rights to export chat invite link"));
+  }
+
+  td_->create_handler<ExportChatInviteLinkQuery>(std::move(promise))->send(chat_id);
+}
+
+void ContactsManager::export_channel_invite_link(ChannelId channel_id, Promise<Unit> &&promise) {
+  const Channel *c = get_channel(channel_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(3, "Chat info not found"));
+  }
+
+  if (!get_channel_status(c).can_export_dialog_invite_link()) {
+    return promise.set_error(Status::Error(3, "Not enough rights to export chat invite link"));
+  }
+
+  td_->create_handler<ExportChannelInviteLinkQuery>(std::move(promise))->send(channel_id);
+}
+
+void ContactsManager::check_dialog_invite_link(const string &invite_link, Promise<Unit> &&promise) const {
+  auto it = invite_link_infos_.find(invite_link);
+  if (it != invite_link_infos_.end()) {
+    return promise.set_value(Unit());
+  }
+
+  if (!is_valid_invite_link(invite_link)) {
+    return promise.set_error(Status::Error(3, "Wrong invite link"));
+  }
+
+  td_->create_handler<CheckDialogInviteLinkQuery>(std::move(promise))->send(invite_link);
+}
+
+void ContactsManager::import_dialog_invite_link(const string &invite_link, Promise<DialogId> &&promise) {
+  if (!is_valid_invite_link(invite_link)) {
+    return promise.set_error(Status::Error(3, "Wrong invite link"));
+  }
+
+  td_->create_handler<ImportDialogInviteLinkQuery>(std::move(promise))->send(invite_link);
+}
+
+string ContactsManager::get_chat_invite_link(ChatId chat_id) const {
+  auto chat_full = get_chat_full(chat_id);
+  if (chat_full == nullptr) {
+    auto it = chat_invite_links_.find(chat_id);
+    return it == chat_invite_links_.end() ? string() : it->second;
+  }
+  return chat_full->invite_link;
+}
+
+string ContactsManager::get_channel_invite_link(
+    ChannelId channel_id) {  // should be non-const to update ChannelFull cache
+  auto channel_full = get_channel_full(channel_id);
+  if (channel_full == nullptr) {
+    auto it = channel_invite_links_.find(channel_id);
+    return it == channel_invite_links_.end() ? string() : it->second;
+  }
+  return channel_full->invite_link;
+}
+
+MessageId ContactsManager::get_channel_pinned_message_id(
+    ChannelId channel_id) {  // should be non-const to update ChannelFull cache
+  auto channel_full = get_channel_full(channel_id);
+  if (channel_full == nullptr) {
+    return MessageId();
+  }
+  return channel_full->pinned_message_id;
+}
+
+void ContactsManager::delete_chat_participant(ChatId chat_id, UserId user_id, Promise<Unit> &&promise) {
+  const Chat *c = get_chat(chat_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(3, "Chat info not found"));
+  }
+  if (!c->is_active) {
+    return promise.set_error(Status::Error(3, "Chat is deactivated"));
+  }
+  auto my_id = get_my_id("delete_chat_participant");
+  if (c->left) {
+    if (user_id == my_id) {
+      return promise.set_value(Unit());
+    } else {
+      return promise.set_error(Status::Error(3, "Not in the chat"));
+    }
+  }
+  if (user_id != my_id) {
+    auto my_status = get_chat_status(c);
+    if (!my_status.is_creator()) {  // creator can delete anyone
+      auto participant = get_chat_participant(chat_id, user_id);
+      if (participant != nullptr) {  // if have no information about participant, just send request to the server
+        if (c->everyone_is_administrator) {
+          // if all are administrators, only invited by me participants can be deleted
+          if (participant->inviter_user_id != my_id) {
+            return promise.set_error(Status::Error(3, "Need to be inviter of a user to kick it from a basic group"));
+          }
+        } else {
+          // otherwise, only creator can kick administrators
+          if (participant->status.is_administrator()) {
+            return promise.set_error(
+                Status::Error(3, "Only the creator of a basic group can kick group administrators"));
+          }
+          // regular users can be kicked by administrators and their inviters
+          if (!my_status.is_administrator() && participant->inviter_user_id != my_id) {
+            return promise.set_error(Status::Error(3, "Need to be inviter of a user to kick it from a basic group"));
+          }
+        }
+      }
+    }
+  }
+  auto input_user = get_input_user(user_id);
+  if (input_user == nullptr) {
+    return promise.set_error(Status::Error(3, "User not found"));
+  }
+
+  // TODO invoke after
+  td_->create_handler<DeleteChatUserQuery>(std::move(promise))->send(chat_id, std::move(input_user));
+}
+
+void ContactsManager::restrict_channel_participant(ChannelId channel_id, UserId user_id, DialogParticipantStatus status,
+                                                   DialogParticipantStatus old_status, Promise<Unit> &&promise) {
+  LOG(INFO) << "Restrict " << user_id << " in " << channel_id << " from " << old_status << " to " << status;
+  const Channel *c = get_channel(channel_id);
+  if (c == nullptr) {
+    return promise.set_error(Status::Error(3, "Chat info not found"));
+  }
+  if (!c->status.is_member()) {
+    if (user_id == get_my_id("restrict_channel_participant")) {
+      if (status.is_member()) {
+        return promise.set_error(Status::Error(3, "Can't unrestrict self"));
+      }
+      return promise.set_value(Unit());
+    } else {
+      return promise.set_error(Status::Error(3, "Not in the chat"));
+    }
+  }
+  auto input_user = get_input_user(user_id);
+  if (input_user == nullptr) {
+    return promise.set_error(Status::Error(3, "User not found"));
+  }
+
+  if (user_id == get_my_id("restrict_channel_participant")) {
+    if (status.is_restricted() || status.is_banned()) {
+      return promise.set_error(Status::Error(3, "Can't restrict self"));
+    }
+    if (status.is_member()) {
+      return promise.set_error(Status::Error(3, "Can't unrestrict self"));
+    }
+
+    // leave the channel
+    td_->create_handler<LeaveChannelQuery>(std::move(promise))->send(channel_id);
+    return;
+  }
+
+  if (status.is_creator()) {
+    return promise.set_error(Status::Error(3, "Not enough rights to restrict chat creator"));
+  }
+
+  if (!get_channel_status(c).can_restrict_members()) {
+    return promise.set_error(Status::Error(3, "Not enough rights to restrict/unrestrict chat member"));
+  }
+
+  if (old_status.is_member() && !status.is_member() && !status.is_banned()) {
+    // we can't make participant Left without kicking it first
+    auto on_result_promise = PromiseCreator::lambda([channel_id, user_id, status,
+                                                     promise = std::move(promise)](Result<> result) mutable {
+      if (result.is_error()) {
+        return promise.set_error(result.move_as_error());
+      }
+
+      create_actor<SleepActor>(
+          "RestrictChannelParticipantSleepActor", 1.0,
+          PromiseCreator::lambda([channel_id, user_id, status, promise = std::move(promise)](Result<> result) mutable {
+            if (result.is_error()) {
+              return promise.set_error(result.move_as_error());
+            }
+
+            send_closure(G()->contacts_manager(), &ContactsManager::restrict_channel_participant, channel_id, user_id,
+                         status, DialogParticipantStatus::Banned(0), std::move(promise));
+          }))
+          .release();
+    });
+
+    promise = std::move(on_result_promise);
+    status = DialogParticipantStatus::Banned(0);
+  }
+
+  speculative_add_channel_users(channel_id, status, old_status);
+  td_->create_handler<EditChannelBannedQuery>(std::move(promise))->send(channel_id, std::move(input_user), status);
+}
+
+ChannelId ContactsManager::migrate_chat_to_megagroup(ChatId chat_id, Promise<Unit> &promise) {
+  auto c = get_chat(chat_id);
+  if (c == nullptr) {
+    promise.set_error(Status::Error(3, "Chat info not found"));
+    return ChannelId();
+  }
+
+  if (!c->is_creator) {
+    promise.set_error(Status::Error(3, "Need creator rights in the chat"));
+    return ChannelId();
+  }
+
+  if (c->migrated_to_channel_id.is_valid()) {
+    return c->migrated_to_channel_id;
+  }
+
+  td_->create_handler<MigrateChatQuery>(std::move(promise))->send(chat_id);
+  return ChannelId();
+}
+
+vector<DialogId> ContactsManager::get_created_public_dialogs(Promise<Unit> &&promise) {
+  if (created_public_channels_inited_) {
+    promise.set_value(Unit());
+    return transform(created_public_channels_, [&](ChannelId channel_id) {
+      DialogId dialog_id(channel_id);
+      td_->messages_manager_->force_create_dialog(dialog_id, "get_created_public_dialogs");
+      return dialog_id;
+    });
+  }
+
+  td_->create_handler<GetCreatedPublicChannelsQuery>(std::move(promise))->send();
+  return {};
+}
+
+void ContactsManager::on_get_created_public_channels(vector<tl_object_ptr<telegram_api::Chat>> &&chats) {
+  created_public_channels_inited_ = true;
+  created_public_channels_.clear();
+
+  for (auto &chat : chats) {
+    switch (chat->get_id()) {
+      case telegram_api::chatEmpty::ID:
+        LOG(ERROR) << "Receive chatEmpty as created public channel";
+        break;
+      case telegram_api::chat::ID:
+        LOG(ERROR) << "Receive chat as created public channel";
+        break;
+      case telegram_api::chatForbidden::ID:
+        LOG(ERROR) << "Receive chatForbidden as created public channel";
+        break;
+      case telegram_api::channel::ID: {
+        auto c = static_cast<const telegram_api::channel *>(chat.get());
+        ChannelId channel_id(c->id_);
+        if (!channel_id.is_valid()) {
+          LOG(ERROR) << "Receive invalid " << channel_id;
+          continue;
+        }
+        created_public_channels_.push_back(channel_id);
+        break;
+      }
+      case telegram_api::channelForbidden::ID: {
+        auto c = static_cast<const telegram_api::channelForbidden *>(chat.get());
+        ChannelId channel_id(c->id_);
+        if (!channel_id.is_valid()) {
+          LOG(ERROR) << "Receive invalid " << channel_id;
+          continue;
+        }
+        created_public_channels_.push_back(channel_id);
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+    on_get_chat(std::move(chat));
+  }
+}
+
+void ContactsManager::on_imported_contacts(int64 random_id, vector<UserId> imported_contact_user_ids,
+                                           vector<int32> unimported_contact_invites) {
+  LOG(INFO) << "Contacts import with random_id " << random_id
+            << " has finished: " << format::as_array(imported_contact_user_ids);
+  if (random_id == 0) {
+    // import from change_imported_contacts
+    all_imported_contacts_ = std::move(next_all_imported_contacts_);
+    next_all_imported_contacts_.clear();
+
+    auto result_size = imported_contacts_unique_id_.size();
+    auto unique_size = all_imported_contacts_.size();
+    auto add_size = imported_contacts_pos_.size();
+
+    imported_contact_user_ids_.resize(result_size);
+    unimported_contact_invites_.resize(result_size);
+
+    CHECK(imported_contact_user_ids.size() == add_size);
+    CHECK(unimported_contact_invites.size() == add_size);
+    CHECK(imported_contacts_unique_id_.size() == result_size);
+
+    std::unordered_map<size_t, int32> unique_id_to_unimported_contact_invites;
+    for (size_t i = 0; i < add_size; i++) {
+      auto unique_id = imported_contacts_pos_[i];
+      get_user_id_object(imported_contact_user_ids[i], "on_imported_contacts");  // to ensure updateUser
+      all_imported_contacts_[unique_id].set_user_id(imported_contact_user_ids[i]);
+      unique_id_to_unimported_contact_invites[unique_id] = unimported_contact_invites[i];
+    }
+
+    if (G()->parameters().use_chat_info_db) {
+      G()->td_db()->get_binlog()->force_sync(PromiseCreator::lambda(
+          [log_event = log_event_store(all_imported_contacts_).as_slice().str()](Result<> result) mutable {
+            if (result.is_ok()) {
+              LOG(INFO) << "Save imported contacts to database";
+              G()->td_db()->get_sqlite_pmc()->set("user_imported_contacts", std::move(log_event), Auto());
+            }
+          }));
+    }
+
+    for (size_t i = 0; i < result_size; i++) {
+      auto unique_id = imported_contacts_unique_id_[i];
+      CHECK(unique_id < unique_size);
+      imported_contact_user_ids_[i] = all_imported_contacts_[unique_id].get_user_id();
+      auto it = unique_id_to_unimported_contact_invites.find(unique_id);
+      if (it == unique_id_to_unimported_contact_invites.end()) {
+        unimported_contact_invites_[i] = 0;
+      } else {
+        unimported_contact_invites_[i] = it->second;
+      }
+    }
+    return;
+  }
+
+  auto it = imported_contacts_.find(random_id);
+  CHECK(it != imported_contacts_.end());
+  CHECK(it->second.first.empty());
+  CHECK(it->second.second.empty());
+  imported_contacts_[random_id] = {std::move(imported_contact_user_ids), std::move(unimported_contact_invites)};
+}
+
+void ContactsManager::on_deleted_contacts(const vector<UserId> &deleted_contact_user_ids) {
+  LOG(INFO) << "Contacts deletion has finished";
+
+  for (auto user_id : deleted_contact_user_ids) {
+    LOG(INFO) << "Drop contact with " << user_id;
+    auto u = get_user(user_id);
+    CHECK(u != nullptr);
+    on_update_user_links(u, user_id, LinkState::KnowsPhoneNumber, u->inbound);
+    update_user(u, user_id);
+    CHECK(u->outbound != LinkState::Contact);
+    CHECK(!contacts_hints_.has_key(user_id.get()));
+  }
+}
+
+void ContactsManager::save_next_contacts_sync_date() {
+  if (!G()->parameters().use_chat_info_db) {
+    return;
+  }
+  G()->td_db()->get_binlog_pmc()->set("next_contacts_sync_date", to_string(next_contacts_sync_date_));
+}
+
+void ContactsManager::on_get_contacts(tl_object_ptr<telegram_api::contacts_Contacts> &&new_contacts) {
+  next_contacts_sync_date_ = G()->unix_time() + Random::fast(70000, 100000);
+
+  CHECK(new_contacts != nullptr);
+  if (new_contacts->get_id() == telegram_api::contacts_contactsNotModified::ID) {
+    if (saved_contact_count_ == -1) {
+      saved_contact_count_ = 0;
+    }
+    on_get_contacts_finished(contacts_hints_.size());
+    td_->create_handler<GetContactsStatusesQuery>()->send();
+    return;
+  }
+
+  auto contacts = move_tl_object_as<telegram_api::contacts_contacts>(new_contacts);
+  std::unordered_set<UserId, UserIdHash> contact_user_ids;
+  for (auto &user : contacts->users_) {
+    auto user_id = get_user_id(user);
+    if (!user_id.is_valid()) {
+      LOG(ERROR) << "Receive invalid " << user_id;
+      continue;
+    }
+    contact_user_ids.insert(user_id);
+  }
+  on_get_users(std::move(contacts->users_));
+
+  UserId my_id = get_my_id("on_get_contacts");
+  for (auto &p : users_) {
+    UserId user_id = p.first;
+    User &u = p.second;
+    bool is_contact = u.outbound == LinkState::Contact;
+    bool should_be_contact = contact_user_ids.count(user_id) == 1;
+    if (is_contact != should_be_contact) {
+      if (is_contact) {
+        LOG(INFO) << "Drop contact with " << user_id;
+        if (user_id != my_id) {
+          CHECK(contacts_hints_.has_key(user_id.get()));
+        }
+        on_update_user_links(&u, user_id, LinkState::KnowsPhoneNumber, u.inbound);
+        update_user(&u, user_id);
+        CHECK(u.outbound != LinkState::Contact);
+        if (user_id != my_id) {
+          CHECK(!contacts_hints_.has_key(user_id.get()));
+        }
+      } else {
+        LOG(ERROR) << "Receive non-contact " << user_id << " in the list of contacts";
+      }
+    }
+  }
+
+  saved_contact_count_ = contacts->saved_count_;
+  on_get_contacts_finished(std::numeric_limits<size_t>::max());
+}
+
+void ContactsManager::save_contacts_to_database() {
+  if (!G()->parameters().use_chat_info_db || !are_contacts_loaded_) {
+    return;
+  }
+
+  LOG(INFO) << "Schedule save contacts to database";
+  vector<UserId> user_ids =
+      transform(contacts_hints_.search_empty(100000).second, [](int64 key) { return UserId(narrow_cast<int32>(key)); });
+
+  G()->td_db()->get_binlog_pmc()->set("saved_contact_count", to_string(saved_contact_count_));
+  G()->td_db()->get_binlog()->force_sync(PromiseCreator::lambda([user_ids = std::move(user_ids)](Result<> result) {
+    if (result.is_ok()) {
+      LOG(INFO) << "Save contacts to database";
+      G()->td_db()->get_sqlite_pmc()->set(
+          "user_contacts", log_event_store(user_ids).as_slice().str(), PromiseCreator::lambda([](Result<> result) {
+            if (result.is_ok()) {
+              send_closure(G()->contacts_manager(), &ContactsManager::save_next_contacts_sync_date);
+            }
+          }));
+    }
+  }));
+}
+
+void ContactsManager::on_get_contacts_failed(Status error) {
+  CHECK(error.is_error());
+  next_contacts_sync_date_ = G()->unix_time() + Random::fast(5, 10);
+  auto promises = std::move(load_contacts_queries_);
+  load_contacts_queries_.clear();
+  for (auto &promise : promises) {
+    promise.set_error(error.clone());
+  }
+}
+
+void ContactsManager::on_load_contacts_from_database(string value) {
+  if (value.empty()) {
+    reload_contacts(true);
+    return;
+  }
+
+  vector<UserId> user_ids;
+  log_event_parse(user_ids, value).ensure();
+
+  LOG(INFO) << "Successfully loaded " << user_ids.size() << " contacts from database";
+
+  load_contact_users_multipromise_.add_promise(
+      PromiseCreator::lambda([expected_contact_count = user_ids.size()](Result<> result) {
+        if (result.is_ok()) {
+          send_closure(G()->contacts_manager(), &ContactsManager::on_get_contacts_finished, expected_contact_count);
+        }
+      }));
+
+  auto lock_promise = load_contact_users_multipromise_.get_promise();
+
+  for (auto user_id : user_ids) {
+    get_user(user_id, 3, load_contact_users_multipromise_.get_promise());
+  }
+
+  lock_promise.set_value(Unit());
+}
+
+void ContactsManager::on_get_contacts_finished(size_t expected_contact_count) {
+  LOG(INFO) << "Finished to get " << contacts_hints_.size() << " contacts out of " << expected_contact_count;
+  are_contacts_loaded_ = true;
+  auto promises = std::move(load_contacts_queries_);
+  load_contacts_queries_.clear();
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+  if (expected_contact_count != contacts_hints_.size()) {
+    save_contacts_to_database();
+  }
+}
+
+void ContactsManager::on_get_contacts_statuses(vector<tl_object_ptr<telegram_api::contactStatus>> &&statuses) {
+  for (auto &status : statuses) {
+    on_update_user_online(UserId(status->user_id_), std::move(status->status_));
+  }
+  save_next_contacts_sync_date();
+}
+
+void ContactsManager::on_update_online_status_privacy() {
+  td_->create_handler<GetContactsStatusesQuery>()->send();
+}
+
+void ContactsManager::on_get_contacts_link(tl_object_ptr<telegram_api::contacts_link> &&link) {
+  UserId user_id = get_user_id(link->user_);
+  on_get_user(std::move(link->user_));
+  on_update_user_links(user_id, std::move(link->my_link_), std::move(link->foreign_link_));
+}
+
+UserId ContactsManager::get_user_id(const tl_object_ptr<telegram_api::User> &user) {
+  CHECK(user != nullptr);
+  switch (user->get_id()) {
+    case telegram_api::userEmpty::ID:
+      return UserId(static_cast<const telegram_api::userEmpty *>(user.get())->id_);
+    case telegram_api::user::ID:
+      return UserId(static_cast<const telegram_api::user *>(user.get())->id_);
+    default:
+      UNREACHABLE();
+      return UserId();
+  }
+}
+
+ChatId ContactsManager::get_chat_id(const tl_object_ptr<telegram_api::Chat> &chat) {
+  CHECK(chat != nullptr);
+  switch (chat->get_id()) {
+    case telegram_api::chatEmpty::ID:
+      return ChatId(static_cast<const telegram_api::chatEmpty *>(chat.get())->id_);
+    case telegram_api::chat::ID:
+      return ChatId(static_cast<const telegram_api::chat *>(chat.get())->id_);
+    case telegram_api::chatForbidden::ID:
+      return ChatId(static_cast<const telegram_api::chatForbidden *>(chat.get())->id_);
+    default:
+      return ChatId();
+  }
+}
+
+ChannelId ContactsManager::get_channel_id(const tl_object_ptr<telegram_api::Chat> &chat) {
+  CHECK(chat != nullptr);
+  switch (chat->get_id()) {
+    case telegram_api::channel::ID:
+      return ChannelId(static_cast<const telegram_api::channel *>(chat.get())->id_);
+    case telegram_api::channelForbidden::ID:
+      return ChannelId(static_cast<const telegram_api::channelForbidden *>(chat.get())->id_);
+    default:
+      return ChannelId();
+  }
+}
+
+void ContactsManager::on_get_user(tl_object_ptr<telegram_api::User> &&user_ptr, bool is_me, bool is_support) {
+  LOG(DEBUG) << "Receive " << to_string(user_ptr);
+  int32 constructor_id = user_ptr->get_id();
+  if (constructor_id == telegram_api::userEmpty::ID) {
+    auto user = move_tl_object_as<telegram_api::userEmpty>(user_ptr);
+    UserId user_id(user->id_);
+    if (!user_id.is_valid()) {
+      LOG(ERROR) << "Receive invalid " << user_id;
+      return;
+    }
+    LOG(INFO) << "Receive empty " << user_id;
+
+    User *u = get_user_force(user_id);
+    if (u == nullptr) {
+      LOG(ERROR) << "Have no information about " << user_id << ", but received userEmpty";
+    }
+    return;
+  }
+
+  CHECK(constructor_id == telegram_api::user::ID);
+  auto user = move_tl_object_as<telegram_api::user>(user_ptr);
+  UserId user_id(user->id_);
+  if (!user_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << user_id;
+    return;
+  }
+  int32 flags = user->flags_;
+  LOG(INFO) << "Receive " << user_id << " with flags " << flags;
+  if (is_me && (flags & USER_FLAG_IS_ME) == 0) {
+    LOG(ERROR) << user_id << " doesn't have flag IS_ME, but must have it";
+    flags |= USER_FLAG_IS_ME;
+  }
+
+  bool is_bot = (flags & USER_FLAG_IS_BOT) != 0;
+  if (flags & USER_FLAG_IS_ME) {
+    set_my_id(user_id);
+    td_->auth_manager_->set_is_bot(is_bot);
+  } else {
+    /*
+    if (!(flags & USER_FLAG_HAS_ACCESS_HASH) && !(flags & USER_FLAG_IS_DELETED) &&
+        !(flags & USER_FLAG_IS_INACCESSIBLE)) {
+      LOG(ERROR) << user_id << " has no access_hash";
+      return;
+    }
+    */
+  }
+
+  if (is_support) {
+    support_user_id_ = user_id;
+  }
+
+  bool have_access_hash = (flags & USER_FLAG_HAS_ACCESS_HASH) != 0;
+  bool is_received = (flags & USER_FLAG_IS_INACCESSIBLE) == 0;
+
+  User *u = add_user(user_id);
+  if ((have_access_hash || u->access_hash == -1) && u->access_hash != user->access_hash_) {
+    LOG(DEBUG) << "Access hash has changed for " << user_id << " from " << u->access_hash << " to "
+               << user->access_hash_;
+    u->access_hash = user->access_hash_;
+    u->is_changed = true;
+  }
+  if (is_received) {
+    on_update_user_phone_number(u, user_id, std::move(user->phone_));
+  }
+  on_update_user_photo(u, user_id, std::move(user->photo_));
+  if (is_received) {
+    on_update_user_online(u, user_id, std::move(user->status_));
+  }
+
+  LinkState out, in;
+  if (flags & USER_FLAG_IS_MUTUAL_CONTACT) {
+    out = LinkState::Contact;
+    in = LinkState::Contact;
+  } else if (flags & USER_FLAG_IS_CONTACT) {
+    out = LinkState::Contact;
+    in = LinkState::Unknown;
+  } else if (flags & USER_FLAG_HAS_PHONE_NUMBER) {
+    out = LinkState::KnowsPhoneNumber;
+    in = LinkState::Unknown;
+  } else {
+    out = LinkState::None;
+    in = LinkState::Unknown;
+  }
+  on_update_user_links(u, user_id, out, in);
+
+  if (is_received || !u->is_received) {
+    on_update_user_name(u, user_id, std::move(user->first_name_), std::move(user->last_name_),
+                        std::move(user->username_));
+  }
+
+  bool is_verified = (flags & USER_FLAG_IS_VERIFIED) != 0;
+  bool is_deleted = (flags & USER_FLAG_IS_DELETED) != 0;
+  bool can_join_groups = (flags & USER_FLAG_IS_PRIVATE_BOT) == 0;
+  bool can_read_all_group_messages = (flags & USER_FLAG_IS_BOT_WITH_PRIVACY_DISABLED) != 0;
+  string restriction_reason = std::move(user->restriction_reason_);
+  bool is_inline_bot = (flags & USER_FLAG_IS_INLINE_BOT) != 0;
+  string inline_query_placeholder = user->bot_inline_placeholder_;
+  bool need_location_bot = (flags & USER_FLAG_NEED_LOCATION_BOT) != 0;
+  bool has_bot_info_version = (flags & USER_FLAG_HAS_BOT_INFO_VERSION) != 0;
+
+  LOG_IF(ERROR, !can_join_groups && !is_bot) << "Receive not bot which can't join groups";
+  LOG_IF(ERROR, can_read_all_group_messages && !is_bot) << "Receive not bot which can read all group messages";
+  LOG_IF(ERROR, is_inline_bot && !is_bot) << "Receive not bot which is inline bot";
+  LOG_IF(ERROR, need_location_bot && !is_inline_bot) << "Receive not inline bot which needs user location";
+
+  if (is_received && !u->is_received) {
+    u->is_received = true;
+
+    LOG(DEBUG) << "Receive " << user_id;
+    u->need_send_update = true;
+  }
+
+  if (is_deleted) {
+    // just in case
+    is_verified = false;
+    is_bot = false;
+    can_join_groups = false;
+    can_read_all_group_messages = false;
+    is_inline_bot = false;
+    inline_query_placeholder = string();
+    need_location_bot = false;
+    has_bot_info_version = false;
+  }
+
+  LOG_IF(ERROR, has_bot_info_version && !is_bot) << "Receive not bot which has bot info version";
+
+  int32 bot_info_version = has_bot_info_version ? user->bot_info_version_ : -1;
+  if (is_verified != u->is_verified || is_bot != u->is_bot || can_join_groups != u->can_join_groups ||
+      can_read_all_group_messages != u->can_read_all_group_messages || restriction_reason != u->restriction_reason ||
+      is_inline_bot != u->is_inline_bot || inline_query_placeholder != u->inline_query_placeholder ||
+      need_location_bot != u->need_location_bot) {
+    LOG_IF(ERROR, is_bot != u->is_bot && !is_deleted && !u->is_deleted) << "User.is_bot has changed";
+    u->is_verified = is_verified;
+    u->is_bot = is_bot;
+    u->can_join_groups = can_join_groups;
+    u->can_read_all_group_messages = can_read_all_group_messages;
+    u->restriction_reason = std::move(restriction_reason);
+    u->is_inline_bot = is_inline_bot;
+    u->inline_query_placeholder = std::move(inline_query_placeholder);
+    u->need_location_bot = need_location_bot;
+
+    LOG(DEBUG) << "Info has changed for " << user_id;
+    u->need_send_update = true;
+  }
+
+  if (u->bot_info_version != bot_info_version) {
+    u->bot_info_version = bot_info_version;
+    LOG(DEBUG) << "Bot info version has changed for " << user_id;
+    u->is_changed = true;
+  }
+
+  if (is_deleted != u->is_deleted) {
+    u->is_deleted = is_deleted;
+
+    if (u->is_deleted) {
+      invalidate_user_full(user_id);
+    }
+
+    LOG(DEBUG) << "is_deleted has changed for " << user_id;
+    u->need_send_update = true;
+  }
+
+  bool has_language_code = (flags & USER_FLAG_HAS_LANGUAGE_CODE) != 0;
+  LOG_IF(ERROR, has_language_code && !td_->auth_manager_->is_bot()) << "Receive language code";
+  if (u->language_code != user->lang_code_ && !user->lang_code_.empty()) {
+    u->language_code = user->lang_code_;
+
+    LOG(DEBUG) << "Language code has changed for " << user_id;
+    u->need_send_update = true;
+  }
+
+  update_user(u, user_id);
+}
+
+class ContactsManager::UserLogEvent {
+ public:
+  UserId user_id;
+  User u;
+
+  UserLogEvent() = default;
+
+  UserLogEvent(UserId user_id, const User &u) : user_id(user_id), u(u) {
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(user_id, storer);
+    td::store(u, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(user_id, parser);
+    td::parse(u, parser);
+  }
+};
+
+void ContactsManager::save_user(User *u, UserId user_id, bool from_binlog) {
+  if (!G()->parameters().use_chat_info_db) {
+    return;
+  }
+  CHECK(u != nullptr);
+  if (!u->is_saved || !u->is_status_saved) {  // TODO more effective handling of !u->is_status_saved
+    if (!from_binlog) {
+      auto logevent = UserLogEvent(user_id, *u);
+      auto storer = LogEventStorerImpl<UserLogEvent>(logevent);
+      if (u->logevent_id == 0) {
+        u->logevent_id = BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::Users, storer);
+      } else {
+        BinlogHelper::rewrite(G()->td_db()->get_binlog(), u->logevent_id, LogEvent::HandlerType::Users, storer);
+      }
+    }
+
+    save_user_to_database(u, user_id);
+  }
+}
+
+void ContactsManager::on_binlog_user_event(BinlogEvent &&event) {
+  if (!G()->parameters().use_chat_info_db) {
+    BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+    return;
+  }
+
+  UserLogEvent log_event;
+  log_event_parse(log_event, event.data_).ensure();
+
+  auto user_id = log_event.user_id;
+  LOG(INFO) << "Add " << user_id << " from binlog";
+  User *u = add_user(user_id);
+  CHECK(u->first_name.empty());
+  *u = std::move(log_event.u);  // users come from binlog before all other events, so just add them
+
+  u->logevent_id = event.id_;
+
+  update_user(u, user_id, true, false);
+}
+
+string ContactsManager::get_user_database_key(UserId user_id) {
+  return "us" + to_string(user_id.get());
+}
+
+string ContactsManager::get_user_database_value(const User *u) {
+  return log_event_store(*u).as_slice().str();
+}
+
+void ContactsManager::save_user_to_database(User *u, UserId user_id) {
+  CHECK(u != nullptr);
+  if (u->is_being_saved) {
+    return;
+  }
+  if (loaded_from_database_users_.count(user_id)) {
+    save_user_to_database_impl(u, user_id, get_user_database_value(u));
+    return;
+  }
+  if (load_user_from_database_queries_.count(user_id) != 0) {
+    return;
+  }
+
+  load_user_from_database_impl(user_id, Auto());
+}
+
+void ContactsManager::save_user_to_database_impl(User *u, UserId user_id, string value) {
+  CHECK(u != nullptr);
+  CHECK(load_user_from_database_queries_.count(user_id) == 0);
+  CHECK(!u->is_being_saved);
+  u->is_being_saved = true;
+  u->is_saved = true;
+  u->is_status_saved = true;
+  LOG(INFO) << "Trying to save to database " << user_id;
+  G()->td_db()->get_sqlite_pmc()->set(
+      get_user_database_key(user_id), std::move(value), PromiseCreator::lambda([user_id](Result<> result) {
+        send_closure(G()->contacts_manager(), &ContactsManager::on_save_user_to_database, user_id, result.is_ok());
+      }));
+}
+
+void ContactsManager::on_save_user_to_database(UserId user_id, bool success) {
+  User *u = get_user(user_id);
+  CHECK(u != nullptr);
+  CHECK(u->is_being_saved);
+  CHECK(load_user_from_database_queries_.count(user_id) == 0);
+  u->is_being_saved = false;
+
+  if (!success) {
+    LOG(ERROR) << "Failed to save " << user_id << " to database";
+    u->is_saved = false;
+    u->is_status_saved = false;
+  } else {
+    LOG(INFO) << "Successfully saved " << user_id << " to database";
+  }
+  if (u->is_saved && u->is_status_saved) {
+    if (u->logevent_id != 0) {
+      BinlogHelper::erase(G()->td_db()->get_binlog(), u->logevent_id);
+      u->logevent_id = 0;
+    }
+  } else {
+    save_user(u, user_id, u->logevent_id != 0);
+  }
+}
+
+void ContactsManager::load_user_from_database(User *u, UserId user_id, Promise<Unit> promise) {
+  if (loaded_from_database_users_.count(user_id)) {
+    promise.set_value(Unit());
+    return;
+  }
+
+  CHECK(u == nullptr || !u->is_being_saved);
+  load_user_from_database_impl(user_id, std::move(promise));
+}
+
+void ContactsManager::load_user_from_database_impl(UserId user_id, Promise<Unit> promise) {
+  LOG(INFO) << "Load " << user_id << " from database";
+  auto &load_user_queries = load_user_from_database_queries_[user_id];
+  load_user_queries.push_back(std::move(promise));
+  if (load_user_queries.size() == 1u) {
+    G()->td_db()->get_sqlite_pmc()->get(get_user_database_key(user_id), PromiseCreator::lambda([user_id](string value) {
+                                          send_closure(G()->contacts_manager(),
+                                                       &ContactsManager::on_load_user_from_database, user_id,
+                                                       std::move(value));
+                                        }));
+  }
+}
+
+void ContactsManager::on_load_user_from_database(UserId user_id, string value) {
+  if (!loaded_from_database_users_.insert(user_id).second) {
+    return;
+  }
+
+  auto it = load_user_from_database_queries_.find(user_id);
+  vector<Promise<Unit>> promises;
+  if (it != load_user_from_database_queries_.end()) {
+    promises = std::move(it->second);
+    CHECK(!promises.empty());
+    load_user_from_database_queries_.erase(it);
+  }
+
+  LOG(INFO) << "Successfully loaded " << user_id << " of size " << value.size() << " from database";
+  //  G()->td_db()->get_sqlite_pmc()->erase(get_user_database_key(user_id), Auto());
+  //  return;
+
+  User *u = get_user(user_id);
+  if (u == nullptr) {
+    if (!value.empty()) {
+      u = add_user(user_id);
+
+      log_event_parse(*u, value).ensure();
+
+      u->is_saved = true;
+      u->is_status_saved = true;
+      update_user(u, user_id, true, true);
+    }
+  } else {
+    CHECK(!u->is_saved);  // user can't be saved before load completes
+    CHECK(!u->is_being_saved);
+    auto new_value = get_user_database_value(u);
+    if (value != new_value) {
+      save_user_to_database_impl(u, user_id, std::move(new_value));
+    } else if (u->logevent_id != 0) {
+      BinlogHelper::erase(G()->td_db()->get_binlog(), u->logevent_id);
+      u->logevent_id = 0;
+    }
+  }
+
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+bool ContactsManager::have_user_force(UserId user_id) {
+  return get_user_force(user_id) != nullptr;
+}
+
+ContactsManager::User *ContactsManager::get_user_force(UserId user_id) {
+  if (!user_id.is_valid()) {
+    return nullptr;
+  }
+
+  User *u = get_user(user_id);
+  if (u != nullptr) {
+    return u;
+  }
+  if (!G()->parameters().use_chat_info_db) {
+    return nullptr;
+  }
+  if (loaded_from_database_users_.count(user_id)) {
+    return nullptr;
+  }
+
+  LOG(INFO) << "Try load " << user_id << " from database";
+  on_load_user_from_database(user_id, G()->td_db()->get_sqlite_sync_pmc()->get(get_user_database_key(user_id)));
+  return get_user(user_id);
+}
+
+class ContactsManager::ChatLogEvent {
+ public:
+  ChatId chat_id;
+  Chat c;
+
+  ChatLogEvent() = default;
+
+  ChatLogEvent(ChatId chat_id, const Chat &c) : chat_id(chat_id), c(c) {
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(chat_id, storer);
+    td::store(c, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(chat_id, parser);
+    td::parse(c, parser);
+  }
+};
+
+void ContactsManager::save_chat(Chat *c, ChatId chat_id, bool from_binlog) {
+  if (!G()->parameters().use_chat_info_db) {
+    return;
+  }
+  CHECK(c != nullptr);
+  if (!c->is_saved) {
+    if (!from_binlog) {
+      auto logevent = ChatLogEvent(chat_id, *c);
+      auto storer = LogEventStorerImpl<ChatLogEvent>(logevent);
+      if (c->logevent_id == 0) {
+        c->logevent_id = BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::Chats, storer);
+      } else {
+        BinlogHelper::rewrite(G()->td_db()->get_binlog(), c->logevent_id, LogEvent::HandlerType::Chats, storer);
+      }
+    }
+
+    save_chat_to_database(c, chat_id);
+    return;
+  }
+}
+
+void ContactsManager::on_binlog_chat_event(BinlogEvent &&event) {
+  if (!G()->parameters().use_chat_info_db) {
+    BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+    return;
+  }
+
+  ChatLogEvent log_event;
+  log_event_parse(log_event, event.data_).ensure();
+
+  auto chat_id = log_event.chat_id;
+  LOG(INFO) << "Add " << chat_id << " from binlog";
+  Chat *c = add_chat(chat_id);
+  CHECK(!c->left && c->kicked);
+  *c = std::move(log_event.c);  // chats come from binlog before all other events, so just add them
+
+  c->logevent_id = event.id_;
+
+  update_chat(c, chat_id, true, false);
+}
+
+string ContactsManager::get_chat_database_key(ChatId chat_id) {
+  return "gr" + to_string(chat_id.get());
+}
+
+string ContactsManager::get_chat_database_value(const Chat *c) {
+  return log_event_store(*c).as_slice().str();
+}
+
+void ContactsManager::save_chat_to_database(Chat *c, ChatId chat_id) {
+  CHECK(c != nullptr);
+  if (c->is_being_saved) {
+    return;
+  }
+  if (loaded_from_database_chats_.count(chat_id)) {
+    save_chat_to_database_impl(c, chat_id, get_chat_database_value(c));
+    return;
+  }
+  if (load_chat_from_database_queries_.count(chat_id) != 0) {
+    return;
+  }
+
+  load_chat_from_database_impl(chat_id, Auto());
+}
+
+void ContactsManager::save_chat_to_database_impl(Chat *c, ChatId chat_id, string value) {
+  CHECK(c != nullptr);
+  CHECK(load_chat_from_database_queries_.count(chat_id) == 0);
+  c->is_being_saved = true;
+  c->is_saved = true;
+  LOG(INFO) << "Trying to save to database " << chat_id;
+  G()->td_db()->get_sqlite_pmc()->set(
+      get_chat_database_key(chat_id), std::move(value), PromiseCreator::lambda([chat_id](Result<> result) {
+        send_closure(G()->contacts_manager(), &ContactsManager::on_save_chat_to_database, chat_id, result.is_ok());
+      }));
+}
+
+void ContactsManager::on_save_chat_to_database(ChatId chat_id, bool success) {
+  Chat *c = get_chat(chat_id);
+  CHECK(c != nullptr);
+  CHECK(c->is_being_saved);
+  CHECK(load_chat_from_database_queries_.count(chat_id) == 0);
+  c->is_being_saved = false;
+
+  if (!success) {
+    LOG(ERROR) << "Failed to save " << chat_id << " to database";
+    c->is_saved = false;
+  } else {
+    LOG(INFO) << "Successfully saved " << chat_id << " to database";
+  }
+  if (c->is_saved) {
+    if (c->logevent_id != 0) {
+      BinlogHelper::erase(G()->td_db()->get_binlog(), c->logevent_id);
+      c->logevent_id = 0;
+    }
+  } else {
+    save_chat(c, chat_id, c->logevent_id != 0);
+  }
+}
+
+void ContactsManager::load_chat_from_database(Chat *c, ChatId chat_id, Promise<Unit> promise) {
+  if (loaded_from_database_chats_.count(chat_id)) {
+    promise.set_value(Unit());
+    return;
+  }
+
+  CHECK(c == nullptr || !c->is_being_saved);
+  load_chat_from_database_impl(chat_id, std::move(promise));
+}
+
+void ContactsManager::load_chat_from_database_impl(ChatId chat_id, Promise<Unit> promise) {
+  LOG(INFO) << "Load " << chat_id << " from database";
+  auto &load_chat_queries = load_chat_from_database_queries_[chat_id];
+  load_chat_queries.push_back(std::move(promise));
+  if (load_chat_queries.size() == 1u) {
+    G()->td_db()->get_sqlite_pmc()->get(get_chat_database_key(chat_id), PromiseCreator::lambda([chat_id](string value) {
+                                          send_closure(G()->contacts_manager(),
+                                                       &ContactsManager::on_load_chat_from_database, chat_id,
+                                                       std::move(value));
+                                        }));
+  }
+}
+
+void ContactsManager::on_load_chat_from_database(ChatId chat_id, string value) {
+  if (!loaded_from_database_chats_.insert(chat_id).second) {
+    return;
+  }
+
+  auto it = load_chat_from_database_queries_.find(chat_id);
+  vector<Promise<Unit>> promises;
+  if (it != load_chat_from_database_queries_.end()) {
+    promises = std::move(it->second);
+    CHECK(!promises.empty());
+    load_chat_from_database_queries_.erase(it);
+  }
+
+  LOG(INFO) << "Successfully loaded " << chat_id << " of size " << value.size() << " from database";
+  //  G()->td_db()->get_sqlite_pmc()->erase(get_chat_database_key(chat_id), Auto());
+  //  return;
+
+  Chat *c = get_chat(chat_id);
+  if (c == nullptr) {
+    if (!value.empty()) {
+      c = add_chat(chat_id);
+
+      log_event_parse(*c, value).ensure();
+
+      c->is_saved = true;
+      update_chat(c, chat_id, true, true);
+    }
+  } else {
+    CHECK(!c->is_saved);  // chat can't be saved before load completes
+    CHECK(!c->is_being_saved);
+    auto new_value = get_chat_database_value(c);
+    if (value != new_value) {
+      save_chat_to_database_impl(c, chat_id, std::move(new_value));
+    } else if (c->logevent_id != 0) {
+      BinlogHelper::erase(G()->td_db()->get_binlog(), c->logevent_id);
+      c->logevent_id = 0;
+    }
+  }
+
+  if (c != nullptr && c->migrated_to_channel_id.is_valid() && !have_channel_force(c->migrated_to_channel_id)) {
+    LOG(ERROR) << "Can't find " << c->migrated_to_channel_id << " from " << chat_id;
+  }
+
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+bool ContactsManager::have_chat_force(ChatId chat_id) {
+  return get_chat_force(chat_id) != nullptr;
+}
+
+ContactsManager::Chat *ContactsManager::get_chat_force(ChatId chat_id) {
+  if (!chat_id.is_valid()) {
+    return nullptr;
+  }
+
+  Chat *c = get_chat(chat_id);
+  if (c != nullptr) {
+    if (c->migrated_to_channel_id.is_valid() && !have_channel_force(c->migrated_to_channel_id)) {
+      LOG(ERROR) << "Can't find " << c->migrated_to_channel_id << " from " << chat_id;
+    }
+
+    return c;
+  }
+  if (!G()->parameters().use_chat_info_db) {
+    return nullptr;
+  }
+  if (loaded_from_database_chats_.count(chat_id)) {
+    return nullptr;
+  }
+
+  LOG(INFO) << "Try load " << chat_id << " from database";
+  on_load_chat_from_database(chat_id, G()->td_db()->get_sqlite_sync_pmc()->get(get_chat_database_key(chat_id)));
+  return get_chat(chat_id);
+}
+
+class ContactsManager::ChannelLogEvent {
+ public:
+  ChannelId channel_id;
+  Channel c;
+
+  ChannelLogEvent() = default;
+
+  ChannelLogEvent(ChannelId channel_id, const Channel &c) : channel_id(channel_id), c(c) {
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(channel_id, storer);
+    td::store(c, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(channel_id, parser);
+    td::parse(c, parser);
+  }
+};
+
+void ContactsManager::save_channel(Channel *c, ChannelId channel_id, bool from_binlog) {
+  if (!G()->parameters().use_chat_info_db) {
+    return;
+  }
+  CHECK(c != nullptr);
+  if (!c->is_saved) {
+    if (!from_binlog) {
+      auto logevent = ChannelLogEvent(channel_id, *c);
+      auto storer = LogEventStorerImpl<ChannelLogEvent>(logevent);
+      if (c->logevent_id == 0) {
+        c->logevent_id = BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::Channels, storer);
+      } else {
+        BinlogHelper::rewrite(G()->td_db()->get_binlog(), c->logevent_id, LogEvent::HandlerType::Channels, storer);
+      }
+    }
+
+    save_channel_to_database(c, channel_id);
+    return;
+  }
+}
+
+void ContactsManager::on_binlog_channel_event(BinlogEvent &&event) {
+  if (!G()->parameters().use_chat_info_db) {
+    BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+    return;
+  }
+
+  ChannelLogEvent log_event;
+  log_event_parse(log_event, event.data_).ensure();
+
+  auto channel_id = log_event.channel_id;
+  LOG(INFO) << "Add " << channel_id << " from binlog";
+  Channel *c = add_channel(channel_id);
+  CHECK(c->status.is_banned());
+  *c = std::move(log_event.c);  // channels come from binlog before all other events, so just add them
+
+  c->logevent_id = event.id_;
+
+  update_channel(c, channel_id, true, false);
+}
+
+string ContactsManager::get_channel_database_key(ChannelId channel_id) {
+  return "ch" + to_string(channel_id.get());
+}
+
+string ContactsManager::get_channel_database_value(const Channel *c) {
+  return log_event_store(*c).as_slice().str();
+}
+
+void ContactsManager::save_channel_to_database(Channel *c, ChannelId channel_id) {
+  CHECK(c != nullptr);
+  if (c->is_being_saved) {
+    return;
+  }
+  if (loaded_from_database_channels_.count(channel_id)) {
+    save_channel_to_database_impl(c, channel_id, get_channel_database_value(c));
+    return;
+  }
+  if (load_channel_from_database_queries_.count(channel_id) != 0) {
+    return;
+  }
+
+  load_channel_from_database_impl(channel_id, Auto());
+}
+
+void ContactsManager::save_channel_to_database_impl(Channel *c, ChannelId channel_id, string value) {
+  CHECK(c != nullptr);
+  CHECK(load_channel_from_database_queries_.count(channel_id) == 0);
+  c->is_being_saved = true;
+  c->is_saved = true;
+  LOG(INFO) << "Trying to save to database " << channel_id;
+  G()->td_db()->get_sqlite_pmc()->set(
+      get_channel_database_key(channel_id), std::move(value), PromiseCreator::lambda([channel_id](Result<> result) {
+        send_closure(G()->contacts_manager(), &ContactsManager::on_save_channel_to_database, channel_id,
+                     result.is_ok());
+      }));
+}
+
+void ContactsManager::on_save_channel_to_database(ChannelId channel_id, bool success) {
+  Channel *c = get_channel(channel_id);
+  CHECK(c != nullptr);
+  CHECK(c->is_being_saved);
+  CHECK(load_channel_from_database_queries_.count(channel_id) == 0);
+  c->is_being_saved = false;
+
+  if (!success) {
+    LOG(ERROR) << "Failed to save " << channel_id << " to database";
+    c->is_saved = false;
+  } else {
+    LOG(INFO) << "Successfully saved " << channel_id << " to database";
+  }
+  if (c->is_saved) {
+    if (c->logevent_id != 0) {
+      BinlogHelper::erase(G()->td_db()->get_binlog(), c->logevent_id);
+      c->logevent_id = 0;
+    }
+  } else {
+    save_channel(c, channel_id, c->logevent_id != 0);
+  }
+}
+
+void ContactsManager::load_channel_from_database(Channel *c, ChannelId channel_id, Promise<Unit> promise) {
+  if (loaded_from_database_channels_.count(channel_id)) {
+    promise.set_value(Unit());
+    return;
+  }
+
+  CHECK(c == nullptr || !c->is_being_saved);
+  load_channel_from_database_impl(channel_id, std::move(promise));
+}
+
+void ContactsManager::load_channel_from_database_impl(ChannelId channel_id, Promise<Unit> promise) {
+  LOG(INFO) << "Load " << channel_id << " from database";
+  auto &load_channel_queries = load_channel_from_database_queries_[channel_id];
+  load_channel_queries.push_back(std::move(promise));
+  if (load_channel_queries.size() == 1u) {
+    G()->td_db()->get_sqlite_pmc()->get(
+        get_channel_database_key(channel_id), PromiseCreator::lambda([channel_id](string value) {
+          send_closure(G()->contacts_manager(), &ContactsManager::on_load_channel_from_database, channel_id,
+                       std::move(value));
+        }));
+  }
+}
+
+void ContactsManager::on_load_channel_from_database(ChannelId channel_id, string value) {
+  if (!loaded_from_database_channels_.insert(channel_id).second) {
+    return;
+  }
+
+  auto it = load_channel_from_database_queries_.find(channel_id);
+  vector<Promise<Unit>> promises;
+  if (it != load_channel_from_database_queries_.end()) {
+    promises = std::move(it->second);
+    CHECK(!promises.empty());
+    load_channel_from_database_queries_.erase(it);
+  }
+
+  LOG(INFO) << "Successfully loaded " << channel_id << " of size " << value.size() << " from database";
+  //  G()->td_db()->get_sqlite_pmc()->erase(get_channel_database_key(channel_id), Auto());
+  //  return;
+
+  Channel *c = get_channel(channel_id);
+  if (c == nullptr) {
+    if (!value.empty()) {
+      c = add_channel(channel_id);
+
+      log_event_parse(*c, value).ensure();
+
+      c->is_saved = true;
+      update_channel(c, channel_id, true, true);
+    }
+  } else {
+    CHECK(!c->is_saved);  // channel can't be saved before load completes
+    CHECK(!c->is_being_saved);
+    auto new_value = get_channel_database_value(c);
+    if (value != new_value) {
+      save_channel_to_database_impl(c, channel_id, std::move(new_value));
+    } else if (c->logevent_id != 0) {
+      BinlogHelper::erase(G()->td_db()->get_binlog(), c->logevent_id);
+      c->logevent_id = 0;
+    }
+  }
+
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+bool ContactsManager::have_channel_force(ChannelId channel_id) {
+  return get_channel_force(channel_id) != nullptr;
+}
+
+ContactsManager::Channel *ContactsManager::get_channel_force(ChannelId channel_id) {
+  if (!channel_id.is_valid()) {
+    return nullptr;
+  }
+
+  Channel *c = get_channel(channel_id);
+  if (c != nullptr) {
+    return c;
+  }
+  if (!G()->parameters().use_chat_info_db) {
+    return nullptr;
+  }
+  if (loaded_from_database_channels_.count(channel_id)) {
+    return nullptr;
+  }
+
+  LOG(INFO) << "Try load " << channel_id << " from database";
+  on_load_channel_from_database(channel_id,
+                                G()->td_db()->get_sqlite_sync_pmc()->get(get_channel_database_key(channel_id)));
+  return get_channel(channel_id);
+}
+
+class ContactsManager::SecretChatLogEvent {
+ public:
+  SecretChatId secret_chat_id;
+  SecretChat c;
+
+  SecretChatLogEvent() = default;
+
+  SecretChatLogEvent(SecretChatId secret_chat_id, const SecretChat &c) : secret_chat_id(secret_chat_id), c(c) {
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(secret_chat_id, storer);
+    td::store(c, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(secret_chat_id, parser);
+    td::parse(c, parser);
+  }
+};
+
+void ContactsManager::save_secret_chat(SecretChat *c, SecretChatId secret_chat_id, bool from_binlog) {
+  if (!G()->parameters().use_chat_info_db) {
+    return;
+  }
+  CHECK(c != nullptr);
+  if (!c->is_saved) {
+    if (!from_binlog) {
+      auto logevent = SecretChatLogEvent(secret_chat_id, *c);
+      auto storer = LogEventStorerImpl<SecretChatLogEvent>(logevent);
+      if (c->logevent_id == 0) {
+        c->logevent_id = BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::SecretChatInfos, storer);
+      } else {
+        BinlogHelper::rewrite(G()->td_db()->get_binlog(), c->logevent_id, LogEvent::HandlerType::SecretChatInfos,
+                              storer);
+      }
+    }
+
+    save_secret_chat_to_database(c, secret_chat_id);
+    return;
+  }
+}
+
+void ContactsManager::on_binlog_secret_chat_event(BinlogEvent &&event) {
+  if (!G()->parameters().use_chat_info_db) {
+    BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+    return;
+  }
+
+  SecretChatLogEvent log_event;
+  log_event_parse(log_event, event.data_).ensure();
+
+  auto secret_chat_id = log_event.secret_chat_id;
+  LOG(INFO) << "Add " << secret_chat_id << " from binlog";
+  SecretChat *c = add_secret_chat(secret_chat_id);
+  CHECK(c->date == 0);
+  *c = std::move(log_event.c);  // secret chats come from binlog before all other events, so just add them
+
+  c->logevent_id = event.id_;
+
+  update_secret_chat(c, secret_chat_id, true, false);
+}
+
+string ContactsManager::get_secret_chat_database_key(SecretChatId secret_chat_id) {
+  return "sc" + to_string(secret_chat_id.get());
+}
+
+string ContactsManager::get_secret_chat_database_value(const SecretChat *c) {
+  return log_event_store(*c).as_slice().str();
+}
+
+void ContactsManager::save_secret_chat_to_database(SecretChat *c, SecretChatId secret_chat_id) {
+  CHECK(c != nullptr);
+  if (c->is_being_saved) {
+    return;
+  }
+  if (loaded_from_database_secret_chats_.count(secret_chat_id)) {
+    save_secret_chat_to_database_impl(c, secret_chat_id, get_secret_chat_database_value(c));
+    return;
+  }
+  if (load_secret_chat_from_database_queries_.count(secret_chat_id) != 0) {
+    return;
+  }
+
+  load_secret_chat_from_database_impl(secret_chat_id, Auto());
+}
+
+void ContactsManager::save_secret_chat_to_database_impl(SecretChat *c, SecretChatId secret_chat_id, string value) {
+  CHECK(c != nullptr);
+  CHECK(load_secret_chat_from_database_queries_.count(secret_chat_id) == 0);
+  c->is_being_saved = true;
+  c->is_saved = true;
+  LOG(INFO) << "Trying to save to database " << secret_chat_id;
+  G()->td_db()->get_sqlite_pmc()->set(get_secret_chat_database_key(secret_chat_id), std::move(value),
+                                      PromiseCreator::lambda([secret_chat_id](Result<> result) {
+                                        send_closure(G()->contacts_manager(),
+                                                     &ContactsManager::on_save_secret_chat_to_database, secret_chat_id,
+                                                     result.is_ok());
+                                      }));
+}
+
+void ContactsManager::on_save_secret_chat_to_database(SecretChatId secret_chat_id, bool success) {
+  SecretChat *c = get_secret_chat(secret_chat_id);
+  CHECK(c != nullptr);
+  CHECK(c->is_being_saved);
+  CHECK(load_secret_chat_from_database_queries_.count(secret_chat_id) == 0);
+  c->is_being_saved = false;
+
+  if (!success) {
+    LOG(ERROR) << "Failed to save " << secret_chat_id << " to database";
+    c->is_saved = false;
+  } else {
+    LOG(INFO) << "Successfully saved " << secret_chat_id << " to database";
+  }
+  if (c->is_saved) {
+    if (c->logevent_id != 0) {
+      BinlogHelper::erase(G()->td_db()->get_binlog(), c->logevent_id);
+      c->logevent_id = 0;
+    }
+  } else {
+    save_secret_chat(c, secret_chat_id, c->logevent_id != 0);
+  }
+}
+
+void ContactsManager::load_secret_chat_from_database(SecretChat *c, SecretChatId secret_chat_id,
+                                                     Promise<Unit> promise) {
+  if (loaded_from_database_secret_chats_.count(secret_chat_id)) {
+    promise.set_value(Unit());
+    return;
+  }
+
+  CHECK(c == nullptr || !c->is_being_saved);
+  load_secret_chat_from_database_impl(secret_chat_id, std::move(promise));
+}
+
+void ContactsManager::load_secret_chat_from_database_impl(SecretChatId secret_chat_id, Promise<Unit> promise) {
+  LOG(INFO) << "Load " << secret_chat_id << " from database";
+  auto &load_secret_chat_queries = load_secret_chat_from_database_queries_[secret_chat_id];
+  load_secret_chat_queries.push_back(std::move(promise));
+  if (load_secret_chat_queries.size() == 1u) {
+    G()->td_db()->get_sqlite_pmc()->get(
+        get_secret_chat_database_key(secret_chat_id), PromiseCreator::lambda([secret_chat_id](string value) {
+          send_closure(G()->contacts_manager(), &ContactsManager::on_load_secret_chat_from_database, secret_chat_id,
+                       std::move(value));
+        }));
+  }
+}
+
+void ContactsManager::on_load_secret_chat_from_database(SecretChatId secret_chat_id, string value) {
+  if (!loaded_from_database_secret_chats_.insert(secret_chat_id).second) {
+    return;
+  }
+
+  auto it = load_secret_chat_from_database_queries_.find(secret_chat_id);
+  vector<Promise<Unit>> promises;
+  if (it != load_secret_chat_from_database_queries_.end()) {
+    promises = std::move(it->second);
+    CHECK(!promises.empty());
+    load_secret_chat_from_database_queries_.erase(it);
+  }
+
+  LOG(INFO) << "Successfully loaded " << secret_chat_id << " of size " << value.size() << " from database";
+  //  G()->td_db()->get_sqlite_pmc()->erase(get_secret_chat_database_key(secret_chat_id), Auto());
+  //  return;
+
+  SecretChat *c = get_secret_chat(secret_chat_id);
+  if (c == nullptr) {
+    if (!value.empty()) {
+      c = add_secret_chat(secret_chat_id);
+
+      log_event_parse(*c, value).ensure();
+
+      c->is_saved = true;
+      update_secret_chat(c, secret_chat_id, true, true);
+    }
+  } else {
+    CHECK(!c->is_saved);  // secret chat can't be saved before load completes
+    CHECK(!c->is_being_saved);
+    auto new_value = get_secret_chat_database_value(c);
+    if (value != new_value) {
+      save_secret_chat_to_database_impl(c, secret_chat_id, std::move(new_value));
+    } else if (c->logevent_id != 0) {
+      BinlogHelper::erase(G()->td_db()->get_binlog(), c->logevent_id);
+      c->logevent_id = 0;
+    }
+  }
+
+  // TODO load users asynchronously
+  if (c != nullptr && !have_user_force(c->user_id)) {
+    LOG(ERROR) << "Can't find " << c->user_id << " from " << secret_chat_id;
+  }
+
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+bool ContactsManager::have_secret_chat_force(SecretChatId secret_chat_id) {
+  return get_secret_chat_force(secret_chat_id) != nullptr;
+}
+
+ContactsManager::SecretChat *ContactsManager::get_secret_chat_force(SecretChatId secret_chat_id) {
+  if (!secret_chat_id.is_valid()) {
+    return nullptr;
+  }
+
+  SecretChat *c = get_secret_chat(secret_chat_id);
+  if (c != nullptr) {
+    if (!have_user_force(c->user_id)) {
+      LOG(ERROR) << "Can't find " << c->user_id << " from " << secret_chat_id;
+    }
+    return c;
+  }
+  if (!G()->parameters().use_chat_info_db) {
+    return nullptr;
+  }
+  if (loaded_from_database_secret_chats_.count(secret_chat_id)) {
+    return nullptr;
+  }
+
+  LOG(INFO) << "Try load " << secret_chat_id << " from database";
+  on_load_secret_chat_from_database(
+      secret_chat_id, G()->td_db()->get_sqlite_sync_pmc()->get(get_secret_chat_database_key(secret_chat_id)));
+  return get_secret_chat(secret_chat_id);
+}
+
+void ContactsManager::update_user(User *u, UserId user_id, bool from_binlog, bool from_database) {
+  CHECK(u != nullptr);
+  if (u->is_name_changed || u->is_username_changed || u->is_outbound_link_changed) {
+    update_contacts_hints(u, user_id, from_database);
+  }
+  if (u->is_name_changed) {
+    td_->messages_manager_->on_dialog_title_updated(DialogId(user_id));
+    auto it = secret_chats_with_user_.find(user_id);
+    if (it != secret_chats_with_user_.end()) {
+      for (auto secret_chat_id : it->second) {
+        td_->messages_manager_->on_dialog_title_updated(DialogId(secret_chat_id));
+      }
+    }
+  }
+  if (u->is_photo_changed) {
+    td_->messages_manager_->on_dialog_photo_updated(DialogId(user_id));
+    auto it = secret_chats_with_user_.find(user_id);
+    if (it != secret_chats_with_user_.end()) {
+      for (auto secret_chat_id : it->second) {
+        td_->messages_manager_->on_dialog_photo_updated(DialogId(secret_chat_id));
+      }
+    }
+
+    UserFull *user_full = get_user_full(user_id);
+    if (user_full != nullptr) {
+      user_full->photos.clear();
+      if (u->photo.id == 0) {
+        user_full->photo_count = 0;
+      } else {
+        user_full->photo_count = -1;
+      }
+      user_full->photos_offset = user_full->photo_count;
+    }
+  }
+  if (u->is_status_changed && user_id != get_my_id("update_user")) {
+    if (u->was_online >= G()->unix_time_cached()) {
+      auto left_time = u->was_online - G()->server_time_cached() + 2.0;
+      LOG(DEBUG) << "Set online timeout for " << user_id << " in " << left_time;
+      user_online_timeout_.set_timeout_in(user_id.get(), left_time);
+    } else {
+      LOG(DEBUG) << "Cancel online timeout for " << user_id;
+      user_online_timeout_.cancel_timeout(user_id.get());
+    }
+  }
+
+  u->is_name_changed = false;
+  u->is_username_changed = false;
+  u->is_photo_changed = false;
+  u->is_outbound_link_changed = false;
+
+  if (u->is_deleted) {
+    td_->inline_queries_manager_->remove_recent_inline_bot(user_id, Promise<>());
+    /*
+    DialogId dialog_id(user_id);
+    for (auto category : {TopDialogCategory::Correspondent, TopDialogCategory::BotPM, TopDialogCategory::BotInline}) {
+      send_closure(G()->top_dialog_manager(), &TopDialogManager::delete_dialog, category, dialog_id,
+                   get_input_peer_user(user_id, AccessRights::Read));
+    }
+    */
+  }
+
+  LOG(DEBUG) << "Update " << user_id << ": is_changed = " << u->is_changed
+             << ", need_send_update = " << u->need_send_update << ", is_status_chaned = " << u->is_status_changed;
+  if (u->is_changed || u->need_send_update) {
+    if (!from_database) {
+      u->is_saved = false;
+    }
+    if (u->need_send_update) {
+      send_closure(G()->td(), &Td::send_update, make_tl_object<td_api::updateUser>(get_user_object(user_id, u)));
+      u->need_send_update = false;
+      u->is_status_changed = false;
+    }
+    u->is_changed = false;
+  }
+  if (u->is_status_changed) {
+    if (!from_database) {
+      u->is_status_saved = false;
+    }
+    send_closure(G()->td(), &Td::send_update,
+                 make_tl_object<td_api::updateUserStatus>(user_id.get(), get_user_status_object(user_id, u)));
+    u->is_status_changed = false;
+  }
+
+  if (!from_database) {
+    save_user(u, user_id, from_binlog);
+  }
+}
+
+void ContactsManager::update_chat(Chat *c, ChatId chat_id, bool from_binlog, bool from_database) {
+  CHECK(c != nullptr);
+  if (c->is_photo_changed) {
+    td_->messages_manager_->on_dialog_photo_updated(DialogId(chat_id));
+  }
+  if (c->is_title_changed) {
+    td_->messages_manager_->on_dialog_title_updated(DialogId(chat_id));
+  }
+  c->is_photo_changed = false;
+  c->is_title_changed = false;
+
+  LOG(DEBUG) << "Update " << chat_id << ": is_changed = " << c->is_changed
+             << ", need_send_update = " << c->need_send_update;
+  if (c->is_changed || c->need_send_update) {
+    if (!from_database) {
+      c->is_saved = false;
+    }
+    c->is_changed = false;
+    if (c->need_send_update) {
+      send_closure(G()->td(), &Td::send_update,
+                   make_tl_object<td_api::updateBasicGroup>(get_basic_group_object(chat_id, c)));
+      c->need_send_update = false;
+    }
+  }
+
+  if (!from_database) {
+    save_chat(c, chat_id, from_binlog);
+  }
+}
+
+void ContactsManager::update_channel(Channel *c, ChannelId channel_id, bool from_binlog, bool from_database) {
+  CHECK(c != nullptr);
+  if (c->is_photo_changed) {
+    td_->messages_manager_->on_dialog_photo_updated(DialogId(channel_id));
+  }
+  if (c->is_title_changed) {
+    td_->messages_manager_->on_dialog_title_updated(DialogId(channel_id));
+  }
+  if (c->is_status_changed) {
+    c->status.update_restrictions();
+    auto until_date = c->status.get_until_date();
+    int32 left_time = 0;
+    if (until_date > 0) {
+      left_time = until_date - G()->unix_time_cached() + 1;
+      CHECK(left_time > 0);
+    }
+    if (left_time > 0 && left_time < 366 * 86400) {
+      channel_unban_timeout_.set_timeout_in(channel_id.get(), left_time);
+    } else {
+      channel_unban_timeout_.cancel_timeout(channel_id.get());
+    }
+  }
+  if (c->is_username_changed) {
+    if (c->status.is_creator() && created_public_channels_inited_) {
+      if (c->username.empty()) {
+        created_public_channels_.erase(
+            std::remove(created_public_channels_.begin(), created_public_channels_.end(), channel_id),
+            created_public_channels_.end());
+      } else {
+        if (std::find(created_public_channels_.begin(), created_public_channels_.end(), channel_id) ==
+            created_public_channels_.end()) {
+          created_public_channels_.push_back(channel_id);
+        }
+      }
+    }
+  }
+  c->is_photo_changed = false;
+  c->is_title_changed = false;
+  c->is_status_changed = false;
+  c->is_username_changed = false;
+
+  LOG(DEBUG) << "Update " << channel_id << ": is_changed = " << c->is_changed
+             << ", need_send_update = " << c->need_send_update;
+  if (c->is_changed || c->need_send_update) {
+    if (!from_database) {
+      c->is_saved = false;
+    }
+    c->is_changed = false;
+    if (c->need_send_update) {
+      send_closure(G()->td(), &Td::send_update,
+                   make_tl_object<td_api::updateSupergroup>(get_supergroup_object(channel_id, c)));
+      c->need_send_update = false;
+    }
+  }
+
+  if (!from_database) {
+    save_channel(c, channel_id, from_binlog);
+  }
+
+  bool have_read_access = have_input_peer_channel(c, AccessRights::Read);
+  if (c->had_read_access && !have_read_access) {
+    send_closure_later(G()->messages_manager(), &MessagesManager::delete_dialog, DialogId(channel_id));
+  } else if (c->was_member != c->status.is_member()) {
+    DialogId dialog_id(channel_id);
+    send_closure_later(G()->messages_manager(), &MessagesManager::force_create_dialog, dialog_id, "update channel",
+                       true);
+  }
+  c->had_read_access = have_read_access;
+  c->was_member = c->status.is_member();
+}
+
+void ContactsManager::update_secret_chat(SecretChat *c, SecretChatId secret_chat_id, bool from_binlog,
+                                         bool from_database) {
+  CHECK(c != nullptr);
+  LOG(DEBUG) << "Update " << secret_chat_id << ": is_changed = " << c->is_changed
+             << ", need_send_update = " << c->need_send_update;
+  if (c->is_changed || c->need_send_update) {
+    if (!from_database) {
+      c->is_saved = false;
+    }
+    c->is_changed = false;
+    if (c->need_send_update) {
+      send_closure(G()->td(), &Td::send_update,
+                   make_tl_object<td_api::updateSecretChat>(get_secret_chat_object(secret_chat_id, c)));
+      c->need_send_update = false;
+    }
+
+    DialogId dialog_id(secret_chat_id);
+    send_closure_later(G()->messages_manager(), &MessagesManager::force_create_dialog, dialog_id, "update secret chat",
+                       true);
+  }
+
+  if (!from_database) {
+    save_secret_chat(c, secret_chat_id, from_binlog);
+  }
+}
+
+void ContactsManager::update_user_full(UserFull *user_full, UserId user_id) {
+  CHECK(user_full != nullptr);
+  if (user_full->is_changed) {
+    user_full->is_changed = false;
+    if (user_full->is_inited) {
+      send_closure(G()->td(), &Td::send_update,
+                   make_tl_object<td_api::updateUserFullInfo>(get_user_id_object(user_id, "updateUserFullInfo"),
+                                                              get_user_full_info_object(user_id, user_full)));
+    }
+  }
+}
+
+void ContactsManager::update_chat_full(ChatFull *chat_full, ChatId chat_id) {
+  CHECK(chat_full != nullptr);
+  if (chat_full->is_changed) {
+    vector<UserId> administrator_user_ids;
+    for (auto &participant : chat_full->participants) {
+      if (participant.status.is_administrator()) {
+        administrator_user_ids.push_back(participant.user_id);
+      }
+    }
+    on_update_dialog_administrators(DialogId(chat_id), std::move(administrator_user_ids), chat_full->version != -1);
+
+    chat_full->is_changed = false;
+    send_closure(
+        G()->td(), &Td::send_update,
+        make_tl_object<td_api::updateBasicGroupFullInfo>(get_basic_group_id_object(chat_id, "update_chat_full"),
+                                                         get_basic_group_full_info_object(chat_full)));
+  }
+}
+
+void ContactsManager::update_channel_full(ChannelFull *channel_full, ChannelId channel_id) {
+  CHECK(channel_full != nullptr);
+  if (channel_full->is_changed) {
+    if (channel_full->participant_count < channel_full->administrator_count) {
+      channel_full->administrator_count = channel_full->participant_count;
+    }
+    channel_full->is_changed = false;
+    send_closure(
+        G()->td(), &Td::send_update,
+        make_tl_object<td_api::updateSupergroupFullInfo>(get_supergroup_id_object(channel_id, "update_channel_full"),
+                                                         get_channel_full_info_object(channel_full)));
+  }
+}
+
+void ContactsManager::on_get_users(vector<tl_object_ptr<telegram_api::User>> &&users) {
+  for (auto &user : users) {
+    on_get_user(std::move(user));
+  }
+}
+
+void ContactsManager::on_get_user_full(tl_object_ptr<telegram_api::userFull> &&user_full) {
+  UserId user_id = get_user_id(user_full->user_);
+  if (!user_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << user_id;
+    return;
+  }
+
+  on_get_user(std::move(user_full->user_));
+  const User *u = get_user(user_id);
+  if (u == nullptr) {
+    return;
+  }
+
+  on_update_user_links(user_id, std::move(user_full->link_->my_link_), std::move(user_full->link_->foreign_link_));
+  td_->messages_manager_->on_update_notify_settings(DialogId(user_id).get(), std::move(user_full->notify_settings_));
+
+  UserFull *user = &users_full_[user_id];
+  user->expires_at = Time::now() + USER_FULL_EXPIRE_TIME;
+  user->is_inited = true;
+
+  on_update_user_full_is_blocked(user, user_id, (user_full->flags_ & USER_FULL_FLAG_IS_BLOCKED) != 0);
+
+  bool can_be_called = user_full->phone_calls_available_ && !user_full->phone_calls_private_;
+  bool has_private_calls = user_full->phone_calls_private_;
+  if (user->can_be_called != can_be_called || user->has_private_calls != has_private_calls ||
+      user->about != user_full->about_ || user->common_chat_count != user_full->common_chats_count_) {
+    user->can_be_called = can_be_called;
+    user->has_private_calls = has_private_calls;
+    user->about = std::move(user_full->about_);
+    user->common_chat_count = user_full->common_chats_count_;
+
+    user->is_changed = true;
+  }
+
+  int32 photo_id =
+      user_full->profile_photo_ == nullptr ? telegram_api::photoEmpty::ID : user_full->profile_photo_->get_id();
+  if (photo_id == telegram_api::photoEmpty::ID) {
+    user->photo_count = 0;
+    user->photos_offset = 0;
+    user->photos.clear();
+  } else {
+    CHECK(photo_id == telegram_api::photo::ID);
+
+    //    Photo profile_photo =
+    //        get_photo(td_->file_manager_.get(), move_tl_object_as<telegram_api::photo>(user_full->profile_photo_));
+  }
+
+  if ((user_full->flags_ & USER_FULL_FLAG_HAS_BOT_INFO) != 0 && !u->is_deleted) {
+    on_update_user_full_bot_info(user, user_id, u->bot_info_version, std::move(user_full->bot_info_));
+  }
+  update_user_full(user, user_id);
+}
+
+void ContactsManager::on_get_user_photos(UserId user_id, int32 offset, int32 limit, int32 total_count,
+                                         vector<tl_object_ptr<telegram_api::Photo>> photos) {
+  int32 photo_count = narrow_cast<int32>(photos.size());
+  if (total_count < 0 || total_count < photo_count) {
+    LOG(ERROR) << "Wrong photos total_count " << total_count << ". Receive " << photo_count << " photos";
+    total_count = photo_count;
+  }
+  LOG_IF(ERROR, limit < photo_count) << "Requested not more than " << limit << " photos, but " << photo_count
+                                     << " returned";
+
+  UserFull *user = &users_full_[user_id];
+  user->photo_count = total_count;
+  CHECK(user->getting_photos_now);
+  user->getting_photos_now = false;
+
+  if (user->photos_offset == -1) {
+    user->photos_offset = 0;
+    CHECK(user->photos.empty());
+  }
+
+  if (offset != narrow_cast<int32>(user->photos.size()) + user->photos_offset) {
+    LOG(INFO) << "Inappropriate offset to append " << user_id << " profile photos to cache: offset = " << offset
+              << ", current_offset = " << user->photos_offset << ", photo_count = " << user->photos.size();
+    user->photos.clear();
+    user->photos_offset = offset;
+  }
+
+  for (auto &photo : photos) {
+    int32 photo_id = photo->get_id();
+    if (photo_id == telegram_api::photoEmpty::ID) {
+      LOG(ERROR) << "Have got empty profile photo in getUserPhotos request for " << user_id << " with offset " << offset
+                 << " and limit " << limit << ". Receive " << photo_count << " photos out of " << total_count
+                 << " photos";
+      continue;
+    }
+    CHECK(photo_id == telegram_api::photo::ID);
+
+    user->photos.push_back(
+        get_photo(td_->file_manager_.get(), move_tl_object_as<telegram_api::photo>(photo), DialogId()));
+  }
+}
+
+bool ContactsManager::on_update_bot_info(tl_object_ptr<telegram_api::botInfo> &&bot_info) {
+  CHECK(bot_info != nullptr);
+  UserId user_id(bot_info->user_id_);
+  if (!user_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << user_id;
+    return false;
+  }
+
+  const User *u = get_user_force(user_id);
+  if (u == nullptr) {
+    LOG(ERROR) << "Have no " << user_id;
+    return false;
+  }
+
+  if (u->is_deleted) {
+    return false;
+  }
+
+  UserFull *user_full = &users_full_[user_id];
+  bool result = on_update_user_full_bot_info(user_full, user_id, u->bot_info_version, std::move(bot_info));
+  update_user_full(user_full, user_id);
+  return result;
+}
+
+bool ContactsManager::on_update_user_full_bot_info(UserFull *user_full, UserId user_id, int32 bot_info_version,
+                                                   tl_object_ptr<telegram_api::botInfo> &&bot_info) {
+  CHECK(user_full != nullptr);
+  CHECK(bot_info != nullptr);
+
+  if (user_full->bot_info != nullptr && user_full->bot_info->version > bot_info_version) {
+    LOG(WARNING) << "Ignore outdated version of BotInfo for " << user_id << " with version " << bot_info_version
+                 << ", current version is " << user_full->bot_info->version;
+    return false;
+  }
+  if (user_full->bot_info != nullptr && user_full->bot_info->version == bot_info_version) {
+    LOG(DEBUG) << "Ignore already known version of BotInfo for " << user_id << " with version " << bot_info_version;
+    return false;
+  }
+
+  vector<std::pair<string, string>> commands;
+  commands.reserve(bot_info->commands_.size());
+  for (auto &command : bot_info->commands_) {
+    commands.emplace_back(std::move(command->command_), std::move(command->description_));
+  }
+  user_full->bot_info = make_unique<BotInfo>(bot_info_version, std::move(bot_info->description_), std::move(commands));
+  user_full->is_changed = true;
+  return true;
+}
+
+void ContactsManager::on_get_chat(tl_object_ptr<telegram_api::Chat> &&chat) {
+  LOG(DEBUG) << "Receive " << to_string(chat);
+  downcast_call(*chat, OnChatUpdate(this));
+}
+
+void ContactsManager::on_get_chats(vector<tl_object_ptr<telegram_api::Chat>> &&chats) {
+  for (auto &chat : chats) {
+    auto constuctor_id = chat->get_id();
+    if (constuctor_id == telegram_api::channel::ID || constuctor_id == telegram_api::channelForbidden::ID) {
+      // apply info about megagroups before corresponding chats
+      on_get_chat(std::move(chat));
+      chat = nullptr;
+    }
+  }
+  for (auto &chat : chats) {
+    if (chat != nullptr) {
+      on_get_chat(std::move(chat));
+      chat = nullptr;
+    }
+  }
+}
+
+void ContactsManager::on_get_chat_full(tl_object_ptr<telegram_api::ChatFull> &&chat_full_ptr) {
+  if (chat_full_ptr->get_id() == telegram_api::chatFull::ID) {
+    auto chat_full = move_tl_object_as<telegram_api::chatFull>(chat_full_ptr);
+    ChatId chat_id(chat_full->id_);
+    if (!chat_id.is_valid()) {
+      LOG(ERROR) << "Receive invalid " << chat_id;
+      return;
+    }
+
+    ChatFull *chat = &chats_full_[chat_id];
+    on_update_chat_full_invite_link(chat, std::move(chat_full->exported_invite_));
+
+    // Ignoring chat_full->photo
+
+    for (auto &bot_info : chat_full->bot_info_) {
+      if (on_update_bot_info(std::move(bot_info))) {
+        chat->is_changed = true;
+      }
+    }
+
+    on_get_chat_participants(std::move(chat_full->participants_));
+    td_->messages_manager_->on_update_notify_settings(DialogId(chat_id).get(), std::move(chat_full->notify_settings_));
+
+    update_chat_full(chat, chat_id);
+  } else {
+    CHECK(chat_full_ptr->get_id() == telegram_api::channelFull::ID);
+    auto channel_full = move_tl_object_as<telegram_api::channelFull>(chat_full_ptr);
+    ChannelId channel_id(channel_full->id_);
+    if (!channel_id.is_valid()) {
+      LOG(ERROR) << "Receive invalid " << channel_id;
+      return;
+    }
+
+    td_->messages_manager_->on_update_notify_settings(DialogId(channel_id).get(),
+                                                      std::move(channel_full->notify_settings_));
+
+    // Ignoring channel_full->photo
+
+    if (!have_channel(channel_id)) {
+      LOG(ERROR) << channel_id << " not found";
+      return;
+    }
+
+    auto participant_count =
+        (channel_full->flags_ & CHANNEL_FULL_FLAG_HAS_PARTICIPANT_COUNT) != 0 ? channel_full->participants_count_ : 0;
+    auto administrator_count =
+        (channel_full->flags_ & CHANNEL_FULL_FLAG_HAS_ADMINISTRATOR_COUNT) != 0 ? channel_full->admins_count_ : 0;
+    auto restricted_count =
+        (channel_full->flags_ & CHANNEL_FULL_FLAG_HAS_BANNED_COUNT) != 0 ? channel_full->banned_count_ : 0;
+    auto banned_count =
+        (channel_full->flags_ & CHANNEL_FULL_FLAG_HAS_BANNED_COUNT) != 0 ? channel_full->kicked_count_ : 0;
+    auto can_get_participants = (channel_full->flags_ & CHANNEL_FULL_FLAG_CAN_GET_PARTICIPANTS) != 0;
+    auto can_set_username = (channel_full->flags_ & CHANNEL_FULL_FLAG_CAN_SET_USERNAME) != 0;
+    auto can_set_sticker_set = (channel_full->flags_ & CHANNEL_FULL_FLAG_CAN_SET_STICKERS) != 0;
+    auto is_all_history_available = (channel_full->flags_ & CHANNEL_FULL_FLAG_IS_ALL_HISTORY_HIDDEN) == 0;
+    int64 sticker_set_id = channel_full->stickerset_ == nullptr
+                               ? 0
+                               : td_->stickers_manager_->on_get_sticker_set(std::move(channel_full->stickerset_), true);
+
+    ChannelFull *channel = &channels_full_[channel_id];
+    channel->expires_at = Time::now() + CHANNEL_FULL_EXPIRE_TIME;
+    if (channel->description != channel_full->about_ || channel->participant_count != participant_count ||
+        channel->administrator_count != administrator_count || channel->restricted_count != restricted_count ||
+        channel->banned_count != banned_count || channel->can_get_participants != can_get_participants ||
+        channel->can_set_username != can_set_username || channel->can_set_sticker_set != can_set_sticker_set ||
+        channel->sticker_set_id != sticker_set_id || channel->is_all_history_available != is_all_history_available) {
+      channel->description = std::move(channel_full->about_);
+      channel->participant_count = participant_count;
+      channel->administrator_count = administrator_count;
+      channel->restricted_count = restricted_count;
+      channel->banned_count = banned_count;
+      channel->can_get_participants = can_get_participants;
+      channel->can_set_username = can_set_username;
+      channel->can_set_sticker_set = can_set_sticker_set;
+      channel->sticker_set_id = sticker_set_id;
+      channel->is_all_history_available = is_all_history_available;
+
+      channel->is_changed = true;
+
+      if (participant_count != 0) {
+        auto c = get_channel(channel_id);
+        if (c != nullptr && c->participant_count != participant_count) {
+          c->participant_count = participant_count;
+          c->need_send_update = true;
+          update_channel(c, channel_id);
+        }
+      }
+    }
+
+    td_->messages_manager_->on_read_channel_outbox(channel_id,
+                                                   MessageId(ServerMessageId(channel_full->read_outbox_max_id_)));
+    if ((channel_full->flags_ & CHANNEL_FULL_FLAG_HAS_AVAILABLE_MIN_MESSAGE_ID) != 0) {
+      td_->messages_manager_->on_update_channel_max_unavailable_message_id(
+          channel_id, MessageId(ServerMessageId(channel_full->available_min_id_)));
+    }
+    td_->messages_manager_->on_read_channel_inbox(
+        channel_id, MessageId(ServerMessageId(channel_full->read_inbox_max_id_)), channel_full->unread_count_);
+
+    on_update_channel_full_invite_link(channel, std::move(channel_full->exported_invite_));
+
+    if ((channel_full->flags_ & CHANNEL_FULL_FLAG_HAS_PINNED_MESSAGE) != 0) {
+      on_update_channel_full_pinned_message(channel, MessageId(ServerMessageId(channel_full->pinned_msg_id_)));
+    }
+
+    for (auto &bot_info : channel_full->bot_info_) {
+      on_update_bot_info(std::move(bot_info));
+    }
+
+    ChatId migrated_from_chat_id;
+    MessageId migrated_from_max_message_id;
+
+    if (channel_full->flags_ & CHANNEL_FULL_FLAG_MIGRATED_FROM) {
+      migrated_from_chat_id = ChatId(channel_full->migrated_from_chat_id_);
+      migrated_from_max_message_id = MessageId(ServerMessageId(channel_full->migrated_from_max_id_));
+    }
+
+    if (channel->migrated_from_chat_id != migrated_from_chat_id ||
+        channel->migrated_from_max_message_id != migrated_from_max_message_id) {
+      channel->migrated_from_chat_id = migrated_from_chat_id;
+      channel->migrated_from_max_message_id = migrated_from_max_message_id;
+      channel->is_changed = true;
+    }
+
+    update_channel_full(channel, channel_id);
+  }
+}
+
+bool ContactsManager::is_update_about_username_change_received(UserId user_id) const {
+  const User *u = get_user(user_id);
+  if (u != nullptr) {
+    return u->inbound == LinkState::Contact;
+  } else {
+    return false;
+  }
+}
+
+void ContactsManager::on_update_user_name(UserId user_id, string &&first_name, string &&last_name, string &&username) {
+  if (!user_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << user_id;
+    return;
+  }
+
+  User *u = get_user_force(user_id);
+  if (u != nullptr) {
+    on_update_user_name(u, user_id, std::move(first_name), std::move(last_name), std::move(username));
+    update_user(u, user_id);
+  } else {
+    LOG(INFO) << "Ignore update user name about unknown " << user_id;
+  }
+}
+
+void ContactsManager::on_update_user_name(User *u, UserId user_id, string &&first_name, string &&last_name,
+                                          string &&username) {
+  if (first_name.empty()) {
+    first_name = u->phone_number;
+  }
+  if (u->first_name != first_name || u->last_name != last_name) {
+    u->first_name = std::move(first_name);
+    u->last_name = std::move(last_name);
+    u->is_name_changed = true;
+    LOG(DEBUG) << "Name has changed for " << user_id;
+    u->need_send_update = true;
+  }
+  td_->messages_manager_->on_dialog_username_updated(DialogId(user_id), u->username, username);
+  if (u->username != username) {
+    u->username = std::move(username);
+    u->is_username_changed = true;
+    LOG(DEBUG) << "Username has changed for " << user_id;
+    u->need_send_update = true;
+  }
+}
+
+void ContactsManager::on_update_user_phone_number(UserId user_id, string &&phone_number) {
+  if (!user_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << user_id;
+    return;
+  }
+
+  User *u = get_user_force(user_id);
+  if (u != nullptr) {
+    on_update_user_phone_number(u, user_id, std::move(phone_number));
+    update_user(u, user_id);
+  } else {
+    LOG(INFO) << "Ignore update user phone number about unknown " << user_id;
+  }
+}
+
+void ContactsManager::on_update_user_phone_number(User *u, UserId user_id, string &&phone_number) {
+  if (u->phone_number != phone_number) {
+    u->phone_number = std::move(phone_number);
+    LOG(DEBUG) << "Phone number has changed for " << user_id;
+    u->need_send_update = true;
+  }
+}
+
+void ContactsManager::on_update_user_photo(UserId user_id, tl_object_ptr<telegram_api::UserProfilePhoto> &&photo_ptr) {
+  if (!user_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << user_id;
+    return;
+  }
+
+  User *u = get_user_force(user_id);
+  if (u != nullptr) {
+    on_update_user_photo(u, user_id, std::move(photo_ptr));
+    update_user(u, user_id);
+  } else {
+    LOG(INFO) << "Ignore update user photo about unknown " << user_id;
+  }
+}
+
+void ContactsManager::on_update_user_photo(User *u, UserId user_id,
+                                           tl_object_ptr<telegram_api::UserProfilePhoto> &&photo_ptr) {
+  ProfilePhoto new_photo = get_profile_photo(td_->file_manager_.get(), std::move(photo_ptr));
+
+  if (new_photo != u->photo) {
+    u->photo = new_photo;
+    u->is_photo_changed = true;
+    LOG(DEBUG) << "Photo has changed for " << user_id;
+    u->need_send_update = true;
+  }
+}
+
+void ContactsManager::on_update_user_online(UserId user_id, tl_object_ptr<telegram_api::UserStatus> &&status) {
+  if (!user_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << user_id;
+    return;
+  }
+
+  User *u = get_user_force(user_id);
+  if (u != nullptr) {
+    on_update_user_online(u, user_id, std::move(status));
+    update_user(u, user_id);
+  } else {
+    LOG(INFO) << "Ignore update user online about unknown " << user_id;
+  }
+}
+
+void ContactsManager::on_update_user_online(User *u, UserId user_id, tl_object_ptr<telegram_api::UserStatus> &&status) {
+  int32 id = status == nullptr ? telegram_api::userStatusEmpty::ID : status->get_id();
+  int32 new_online;
+  bool is_offline = false;
+  if (id == telegram_api::userStatusOnline::ID) {
+    int32 now = G()->unix_time();
+
+    auto st = move_tl_object_as<telegram_api::userStatusOnline>(status);
+    new_online = st->expires_;
+    LOG_IF(ERROR, new_online < now - 86400)
+        << "Receive userStatusOnline expired more than one day in past " << new_online;
+  } else if (id == telegram_api::userStatusOffline::ID) {
+    int32 now = G()->unix_time();
+
+    auto st = move_tl_object_as<telegram_api::userStatusOffline>(status);
+    new_online = st->was_online_;
+    if (new_online >= now) {
+      LOG_IF(ERROR, new_online > now + 10)
+          << "Receive userStatusOffline but was online points to future time " << new_online << ", now is " << now;
+      new_online = now - 1;
+    }
+    is_offline = true;
+  } else if (id == telegram_api::userStatusRecently::ID) {
+    new_online = -1;
+  } else if (id == telegram_api::userStatusLastWeek::ID) {
+    new_online = -2;
+    is_offline = true;
+  } else if (id == telegram_api::userStatusLastMonth::ID) {
+    new_online = -3;
+    is_offline = true;
+  } else {
+    CHECK(id == telegram_api::userStatusEmpty::ID);
+    new_online = 0;
+  }
+
+  if (new_online != u->was_online) {
+    LOG(DEBUG) << "Update " << user_id << " online from " << u->was_online << " to " << new_online;
+    u->was_online = new_online;
+    u->is_status_changed = true;
+
+    if (user_id == get_my_id("on_update_user_online")) {
+      my_was_online_local_ = 0;
+      if (is_offline) {
+        td_->on_online_updated(false, false);
+      }
+    }
+  }
+}
+
+void ContactsManager::on_update_user_blocked(UserId user_id, bool is_blocked) {
+  LOG(INFO) << "Receive update user blocked with " << user_id << " and is_blocked = " << is_blocked;
+  if (!user_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << user_id;
+    return;
+  }
+
+  UserFull *user_full = get_user_full(user_id);
+  if (user_full == nullptr) {
+    return;
+  }
+  on_update_user_full_is_blocked(user_full, user_id, is_blocked);
+  update_user_full(user_full, user_id);
+}
+
+void ContactsManager::on_update_user_full_is_blocked(UserFull *user_full, UserId user_id, bool is_blocked) {
+  CHECK(user_full != nullptr);
+  if (user_full->is_inited && user_full->is_blocked != is_blocked) {
+    user_full->is_blocked = is_blocked;
+    user_full->is_changed = true;
+  }
+}
+
+void ContactsManager::on_delete_profile_photo(int64 profile_photo_id, Promise<Unit> promise) {
+  UserId my_id = get_my_id("on_delete_profile_photo");
+
+  UserFull *user_full = get_user_full(my_id);
+  if (user_full != nullptr) {
+    // drop photo cache
+    user_full->photos.clear();
+    user_full->photo_count = -1;
+    user_full->photos_offset = -1;
+  }
+
+  auto input_user = get_input_user(my_id);
+  CHECK(input_user != nullptr);
+  vector<tl_object_ptr<telegram_api::InputUser>> users;
+  users.push_back(std::move(input_user));
+  td_->create_handler<GetUsersQuery>(std::move(promise))->send(std::move(users));
+}
+
+ContactsManager::LinkState ContactsManager::get_link_state(tl_object_ptr<telegram_api::ContactLink> &&link) {
+  int32 id = link->get_id();
+  switch (id) {
+    case telegram_api::contactLinkUnknown::ID:
+      return LinkState::Unknown;
+    case telegram_api::contactLinkNone::ID:
+      return LinkState::None;
+    case telegram_api::contactLinkHasPhone::ID:
+      return LinkState::KnowsPhoneNumber;
+    case telegram_api::contactLinkContact::ID:
+      return LinkState::Contact;
+    default:
+      UNREACHABLE();
+  }
+  return LinkState::Unknown;
+}
+
+void ContactsManager::on_update_user_links(UserId user_id, tl_object_ptr<telegram_api::ContactLink> &&outbound,
+                                           tl_object_ptr<telegram_api::ContactLink> &&inbound) {
+  if (!user_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << user_id;
+    return;
+  }
+
+  User *u = get_user_force(user_id);
+  if (u != nullptr) {
+    on_update_user_links(u, user_id, get_link_state(std::move(outbound)), get_link_state(std::move(inbound)));
+    update_user(u, user_id);
+  } else {
+    LOG(INFO) << "Ignore update user links about unknown " << user_id;
+  }
+}
+
+void ContactsManager::on_update_user_links(User *u, UserId user_id, LinkState outbound, LinkState inbound) {
+  LOG(DEBUG) << "Update " << user_id << " links from (" << u->outbound << ", " << u->inbound << ") to (" << outbound
+             << ", " << inbound << ")";
+  UserId my_id = get_my_id("on_update_user_links");
+  if (user_id == my_id) {
+    if (outbound == LinkState::None && !td_->auth_manager_->is_bot()) {
+      outbound = LinkState::KnowsPhoneNumber;
+    }
+    inbound = outbound;
+  }
+
+  bool need_send_update = false;
+  if (outbound != u->outbound && outbound != LinkState::Unknown) {
+    need_send_update |= outbound != LinkState::None || u->outbound != LinkState::Unknown;
+    LOG(DEBUG) << "Set outbound link to " << outbound << ", need_send_update = " << need_send_update;
+    u->outbound = outbound;
+    u->is_outbound_link_changed = true;
+    u->is_changed = true;
+  }
+  if (inbound != u->inbound && inbound != LinkState::Unknown) {
+    need_send_update |= inbound != LinkState::None || u->inbound != LinkState::Unknown;
+    LOG(DEBUG) << "Set inbound link to " << inbound << ", need_send_update = " << need_send_update;
+    u->inbound = inbound;
+    u->is_changed = true;
+  }
+  if (u->inbound == LinkState::Contact && u->outbound != LinkState::Contact) {
+    u->inbound = LinkState::KnowsPhoneNumber;
+    u->is_changed = true;
+    need_send_update = true;
+  }
+
+  if (need_send_update) {
+    LOG(DEBUG) << "Links have changed for " << user_id;
+    u->need_send_update = true;
+  }
+}
+
+void ContactsManager::invalidate_user_full(UserId user_id) {
+  auto user_full = get_user_full(user_id);
+  if (user_full == nullptr) {
+    return;
+  }
+
+  user_full->expires_at = 0.0;
+
+  user_full->photos.clear();
+  user_full->photo_count = -1;
+  user_full->photos_offset = -1;
+  user_full->is_inited = true;
+  user_full->is_blocked = false;
+  user_full->can_be_called = false;
+  user_full->has_private_calls = false;
+  user_full->about = string();
+  user_full->common_chat_count = 0;
+  user_full->bot_info = nullptr;
+  user_full->is_changed = true;
+
+  update_user_full(user_full, user_id);
+}
+
+void ContactsManager::on_get_chat_participants(tl_object_ptr<telegram_api::ChatParticipants> &&participants_ptr) {
+  switch (participants_ptr->get_id()) {
+    case telegram_api::chatParticipantsForbidden::ID: {
+      auto participants = move_tl_object_as<telegram_api::chatParticipantsForbidden>(participants_ptr);
+      ChatId chat_id(participants->chat_id_);
+      if (!chat_id.is_valid()) {
+        LOG(ERROR) << "Receive invalid " << chat_id;
+        return;
+      }
+
+      if (!have_chat_force(chat_id)) {
+        LOG(ERROR) << chat_id << " not found";
+        return;
+      }
+
+      invalidate_chat_full(chat_id);
+      break;
+    }
+    case telegram_api::chatParticipants::ID: {
+      auto participants = move_tl_object_as<telegram_api::chatParticipants>(participants_ptr);
+      ChatId chat_id(participants->chat_id_);
+      if (!chat_id.is_valid()) {
+        LOG(ERROR) << "Receive invalid " << chat_id;
+        return;
+      }
+
+      const Chat *c = get_chat_force(chat_id);
+      if (c == nullptr) {
+        LOG(ERROR) << chat_id << " not found";
+        return;
+      }
+
+      ChatFull *chat_full = get_chat_full(chat_id);
+      if (chat_full == nullptr) {
+        LOG(INFO) << "Ignore update of members for unknown " << chat_id;
+        return;
+      }
+
+      UserId new_creator_user_id;
+      vector<DialogParticipant> new_participants;
+      new_participants.reserve(participants->participants_.size());
+
+      for (auto &participant_ptr : participants->participants_) {
+        DialogParticipant dialog_participant;
+        switch (participant_ptr->get_id()) {
+          case telegram_api::chatParticipant::ID: {
+            auto participant = move_tl_object_as<telegram_api::chatParticipant>(participant_ptr);
+            dialog_participant = {UserId(participant->user_id_), UserId(participant->inviter_id_), participant->date_,
+                                  DialogParticipantStatus::Member()};
+            break;
+          }
+          case telegram_api::chatParticipantCreator::ID: {
+            auto participant = move_tl_object_as<telegram_api::chatParticipantCreator>(participant_ptr);
+            new_creator_user_id = UserId(participant->user_id_);
+            dialog_participant = {new_creator_user_id, new_creator_user_id, c->date,
+                                  DialogParticipantStatus::Creator(true)};
+            break;
+          }
+          case telegram_api::chatParticipantAdmin::ID: {
+            auto participant = move_tl_object_as<telegram_api::chatParticipantAdmin>(participant_ptr);
+            dialog_participant = {UserId(participant->user_id_), UserId(participant->inviter_id_), participant->date_,
+                                  DialogParticipantStatus::GroupAdministrator(c->is_creator)};
+            break;
+          }
+          default:
+            UNREACHABLE();
+        }
+
+        LOG_IF(ERROR, !have_user(dialog_participant.user_id))
+            << "Have no information about " << dialog_participant.user_id;
+        LOG_IF(ERROR, !have_user(dialog_participant.inviter_user_id))
+            << "Have no information about " << dialog_participant.inviter_user_id;
+        if (dialog_participant.joined_date < c->date) {
+          LOG_IF(ERROR, dialog_participant.joined_date < c->date - 30 && c->date >= 1486000000)
+              << "Wrong join date = " << dialog_participant.joined_date << " for " << dialog_participant.user_id << ", "
+              << chat_id << " was created at " << c->date;
+          dialog_participant.joined_date = c->date;
+        }
+        new_participants.push_back(std::move(dialog_participant));
+      }
+
+      if (new_creator_user_id.is_valid()) {
+        LOG_IF(ERROR, !have_user(new_creator_user_id))
+            << "Have no information about group creator " << new_creator_user_id;
+        if (chat_full->creator_user_id.is_valid() && chat_full->creator_user_id != new_creator_user_id) {
+          LOG(ERROR) << "Group creator has changed from " << chat_full->creator_user_id << " to "
+                     << new_creator_user_id;
+        }
+      }
+      if (chat_full->creator_user_id != new_creator_user_id) {
+        chat_full->creator_user_id = new_creator_user_id;
+        chat_full->is_changed = true;
+      }
+
+      on_update_chat_full_participants(chat_full, chat_id, std::move(new_participants), participants->version_);
+      update_chat_full(chat_full, chat_id);
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+}
+
+const DialogParticipant *ContactsManager::get_chat_participant(ChatId chat_id, UserId user_id) const {
+  auto chat_full = get_chat_full(chat_id);
+  if (chat_full == nullptr) {
+    return nullptr;
+  }
+  return get_chat_participant(chat_full, user_id);
+}
+
+const DialogParticipant *ContactsManager::get_chat_participant(const ChatFull *chat_full, UserId user_id) const {
+  for (auto &dialog_participant : chat_full->participants) {
+    if (dialog_participant.user_id == user_id) {
+      return &dialog_participant;
+    }
+  }
+  return nullptr;
+}
+
+DialogParticipant ContactsManager::get_dialog_participant(
+    ChannelId channel_id, tl_object_ptr<telegram_api::ChannelParticipant> &&participant_ptr) const {
+  switch (participant_ptr->get_id()) {
+    case telegram_api::channelParticipant::ID: {
+      auto participant = move_tl_object_as<telegram_api::channelParticipant>(participant_ptr);
+      return {UserId(participant->user_id_), UserId(), participant->date_, DialogParticipantStatus::Member()};
+    }
+    case telegram_api::channelParticipantSelf::ID: {
+      auto participant = move_tl_object_as<telegram_api::channelParticipantSelf>(participant_ptr);
+      return {UserId(participant->user_id_), UserId(participant->inviter_id_), participant->date_,
+              get_channel_status(channel_id)};
+    }
+    case telegram_api::channelParticipantCreator::ID: {
+      auto participant = move_tl_object_as<telegram_api::channelParticipantCreator>(participant_ptr);
+      return {UserId(participant->user_id_), UserId(), 0, DialogParticipantStatus::Creator(true)};
+    }
+    case telegram_api::channelParticipantAdmin::ID: {
+      auto participant = move_tl_object_as<telegram_api::channelParticipantAdmin>(participant_ptr);
+      bool can_be_edited = (participant->flags_ & telegram_api::channelParticipantAdmin::CAN_EDIT_MASK) != 0;
+      return {UserId(participant->user_id_), UserId(participant->promoted_by_), participant->date_,
+              get_dialog_participant_status(can_be_edited, std::move(participant->admin_rights_))};
+    }
+    case telegram_api::channelParticipantBanned::ID: {
+      auto participant = move_tl_object_as<telegram_api::channelParticipantBanned>(participant_ptr);
+      auto is_member = (participant->flags_ & telegram_api::channelParticipantBanned::LEFT_MASK) == 0;
+      return {UserId(participant->user_id_), UserId(participant->kicked_by_), participant->date_,
+              get_dialog_participant_status(is_member, std::move(participant->banned_rights_))};
+    }
+    default:
+      UNREACHABLE();
+      return DialogParticipant();
+  }
+}
+
+tl_object_ptr<td_api::chatMember> ContactsManager::get_chat_member_object(
+    const DialogParticipant &dialog_participant) const {
+  UserId participant_user_id = dialog_participant.user_id;
+  return make_tl_object<td_api::chatMember>(
+      get_user_id_object(participant_user_id, "chatMember.user_id"),
+      get_user_id_object(dialog_participant.inviter_user_id, "chatMember.inviter_user_id"),
+      dialog_participant.joined_date, dialog_participant.status.get_chat_member_status_object(),
+      get_bot_info_object(participant_user_id));
+}
+
+bool ContactsManager::on_get_channel_error(ChannelId channel_id, const Status &status, const string &source) {
+  LOG(INFO) << "Receive " << status << " in " << channel_id << " from " << source;
+  if (status.message() == CSlice("SESSION_REVOKED") || status.message() == CSlice("USER_DEACTIVATED")) {
+    // authorization is lost
+    return true;
+  }
+  if (status.code() == 420 || status.code() == 429) {
+    // flood wait
+    return true;
+  }
+  if (status.message() == CSlice("BOT_METHOD_INVALID")) {
+    LOG(ERROR) << "Receive BOT_METHOD_INVALID from " << source;
+    return true;
+  }
+  if (status.message() == "CHANNEL_PRIVATE" || status.message() == "CHANNEL_PUBLIC_GROUP_NA") {
+    if (!channel_id.is_valid()) {
+      LOG(ERROR) << "Receive " << status.message() << " in invalid " << channel_id << " from " << source;
+      return false;
+    }
+
+    auto c = get_channel(channel_id);
+    if (c == nullptr) {
+      if (td_->auth_manager_->is_bot() && source == "GetChannelsQuery") {
+        // get channel from server by its identifier
+        return true;
+      }
+      LOG(ERROR) << "Receive " << status.message() << " in not found " << channel_id << " from " << source;
+      return false;
+    }
+
+    auto debug_channel_object = oneline(to_string(get_supergroup_object(channel_id, c)));
+    if (c->status.is_member()) {
+      LOG(INFO) << "Emulate leaving " << channel_id;
+      // TODO we also may try to write to public channel
+      int32 flags = 0;
+      if (c->is_megagroup) {
+        flags |= CHANNEL_FLAG_IS_MEGAGROUP;
+      } else {
+        flags |= CHANNEL_FLAG_IS_BROADCAST;
+      }
+      telegram_api::channelForbidden update(flags, false /*ignored*/, false /*ignored*/, channel_id.get(),
+                                            c->access_hash, c->title, 0);
+      on_chat_update(update);
+    } else if (!c->username.empty()) {
+      LOG(INFO) << "Drop username of " << channel_id;
+      on_update_channel_username(c, channel_id, "");
+      update_channel(c, channel_id);
+    }
+    LOG_IF(ERROR, have_input_peer_channel(c, AccessRights::Read))
+        << "Have read access to channel after receiving CHANNEL_PRIVATE. Channel state: "
+        << oneline(to_string(get_supergroup_object(channel_id, c)))
+        << ". Previous channel state: " << debug_channel_object;
+
+    return true;
+  }
+  return false;
+}
+
+void ContactsManager::on_get_channel_participants_success(
+    ChannelId channel_id, ChannelParticipantsFilter filter, int32 offset, int32 limit, int64 random_id,
+    int32 total_count, vector<tl_object_ptr<telegram_api::ChannelParticipant>> &&participants) {
+  LOG(INFO) << "Receive " << participants.size() << " members in " << channel_id;
+  auto it = received_channel_participants_.find(random_id);
+  CHECK(it != received_channel_participants_.end());
+
+  it->second.first = total_count;
+
+  auto &result = it->second.second;
+  CHECK(result.empty());
+  for (auto &participant_ptr : participants) {
+    result.push_back(get_dialog_participant(channel_id, std::move(participant_ptr)));
+  }
+
+  if (filter.is_administrators() && offset == 0 && static_cast<int32>(participants.size()) < limit) {
+    on_update_dialog_administrators(
+        DialogId(channel_id),
+        transform(result, [](const DialogParticipant &participant) { return participant.user_id; }), true);
+  }
+}
+
+void ContactsManager::on_get_channel_participants_fail(ChannelId channel_id, ChannelParticipantsFilter filter,
+                                                       int32 offset, int32 limit, int64 random_id) {
+  // clean up
+  received_channel_participants_.erase(random_id);
+}
+
+bool ContactsManager::speculative_add_count(int32 &count, int32 new_count) {
+  new_count += count;
+  if (new_count < 0) {
+    new_count = 0;
+  }
+  if (new_count == count) {
+    return false;
+  }
+
+  count = new_count;
+  return true;
+}
+
+void ContactsManager::speculative_add_channel_participants(ChannelId channel_id, int32 new_participant_count,
+                                                           bool by_me) {
+  if (by_me) {
+    // Currently ignore all changes made by the current user, because they may be already counted
+    invalidate_channel_full(channel_id);  // just in case
+    return;
+  }
+
+  auto c = get_channel(channel_id);
+  if (c != nullptr && c->participant_count != 0 && speculative_add_count(c->participant_count, new_participant_count)) {
+    c->need_send_update = true;
+    update_channel(c, channel_id);
+  }
+
+  auto channel_full = get_channel_full(channel_id);
+  if (channel_full == nullptr) {
+    return;
+  }
+
+  channel_full->is_changed |= speculative_add_count(channel_full->participant_count, new_participant_count);
+
+  update_channel_full(channel_full, channel_id);
+}
+
+void ContactsManager::speculative_add_channel_users(ChannelId channel_id, DialogParticipantStatus status,
+                                                    DialogParticipantStatus old_status) {
+  auto c = get_channel(channel_id);
+  if (c != nullptr && c->participant_count != 0 &&
+      speculative_add_count(c->participant_count, status.is_member() - old_status.is_member())) {
+    c->need_send_update = true;
+    update_channel(c, channel_id);
+  }
+
+  auto channel_full = get_channel_full(channel_id);
+  if (channel_full == nullptr) {
+    return;
+  }
+
+  channel_full->is_changed |=
+      speculative_add_count(channel_full->participant_count, status.is_member() - old_status.is_member());
+  channel_full->is_changed |= speculative_add_count(channel_full->administrator_count,
+                                                    status.is_administrator() - old_status.is_administrator());
+  channel_full->is_changed |=
+      speculative_add_count(channel_full->restricted_count, status.is_restricted() - old_status.is_restricted());
+  channel_full->is_changed |=
+      speculative_add_count(channel_full->banned_count, status.is_banned() - old_status.is_banned());
+
+  update_channel_full(channel_full, channel_id);
+}
+
+void ContactsManager::invalidate_channel_full(ChannelId channel_id) {
+  LOG(INFO) << "Invalidate channel full for " << channel_id;
+  // drop channel full cache
+  // TODO at least need to invalidate channel invite link
+  auto channel_full = get_channel_full(channel_id);
+  if (channel_full != nullptr) {
+    channel_full->expires_at = 0.0;
+  }
+
+  // channel_full->is_changed = true;
+  // update_channel_full(channel_full, channel_id);
+}
+
+void ContactsManager::on_get_chat_invite_link(ChatId chat_id,
+                                              tl_object_ptr<telegram_api::ExportedChatInvite> &&invite_link_ptr) {
+  CHECK(chat_id.is_valid());
+  if (!have_chat(chat_id)) {
+    LOG(ERROR) << chat_id << " not found";
+    return;
+  }
+
+  auto chat_full = get_chat_full(chat_id);
+  if (chat_full == nullptr) {
+    update_invite_link(chat_invite_links_[chat_id], std::move(invite_link_ptr));
+    return;
+  }
+  on_update_chat_full_invite_link(chat_full, std::move(invite_link_ptr));
+  update_chat_full(chat_full, chat_id);
+}
+
+void ContactsManager::on_update_chat_full_invite_link(
+    ChatFull *chat_full, tl_object_ptr<telegram_api::ExportedChatInvite> &&invite_link_ptr) {
+  CHECK(chat_full != nullptr);
+  if (update_invite_link(chat_full->invite_link, std::move(invite_link_ptr))) {
+    chat_full->is_changed = true;
+  }
+}
+
+void ContactsManager::on_get_channel_invite_link(ChannelId channel_id,
+                                                 tl_object_ptr<telegram_api::ExportedChatInvite> &&invite_link_ptr) {
+  CHECK(channel_id.is_valid());
+  if (!have_channel(channel_id)) {
+    LOG(ERROR) << channel_id << " not found";
+    return;
+  }
+
+  auto channel_full = get_channel_full(channel_id);
+  if (channel_full == nullptr) {
+    update_invite_link(channel_invite_links_[channel_id], std::move(invite_link_ptr));
+    return;
+  }
+  on_update_channel_full_invite_link(channel_full, std::move(invite_link_ptr));
+  update_channel_full(channel_full, channel_id);
+}
+
+void ContactsManager::on_update_channel_full_invite_link(
+    ChannelFull *channel_full, tl_object_ptr<telegram_api::ExportedChatInvite> &&invite_link_ptr) {
+  CHECK(channel_full != nullptr);
+  if (update_invite_link(channel_full->invite_link, std::move(invite_link_ptr))) {
+    channel_full->is_changed = true;
+  }
+}
+
+void ContactsManager::on_get_dialog_invite_link_info(const string &invite_link,
+                                                     tl_object_ptr<telegram_api::ChatInvite> &&chat_invite_ptr) {
+  auto &invite_link_info = invite_link_infos_[invite_link];
+  if (invite_link_info == nullptr) {
+    invite_link_info = make_unique<InviteLinkInfo>();
+  }
+
+  CHECK(chat_invite_ptr != nullptr);
+  switch (chat_invite_ptr->get_id()) {
+    case telegram_api::chatInviteAlready::ID: {
+      auto chat_invite_already = move_tl_object_as<telegram_api::chatInviteAlready>(chat_invite_ptr);
+      auto chat_id = get_chat_id(chat_invite_already->chat_);
+      if (chat_id != ChatId() && !chat_id.is_valid()) {
+        LOG(ERROR) << "Receive invalid " << chat_id;
+        chat_id = ChatId();
+      }
+      auto channel_id = get_channel_id(chat_invite_already->chat_);
+      if (channel_id != ChannelId() && !channel_id.is_valid()) {
+        LOG(ERROR) << "Receive invalid " << channel_id;
+        channel_id = ChannelId();
+      }
+      on_get_chat(std::move(chat_invite_already->chat_));
+
+      CHECK(chat_id == ChatId() || channel_id == ChannelId());
+      invite_link_info->chat_id = chat_id;
+      invite_link_info->channel_id = channel_id;
+
+      if (chat_id.is_valid()) {
+        on_get_chat_invite_link(chat_id, make_tl_object<telegram_api::chatInviteExported>(invite_link));
+      }
+      if (channel_id.is_valid()) {
+        on_get_channel_invite_link(channel_id, make_tl_object<telegram_api::chatInviteExported>(invite_link));
+      }
+      break;
+    }
+    case telegram_api::chatInvite::ID: {
+      auto chat_invite = move_tl_object_as<telegram_api::chatInvite>(chat_invite_ptr);
+      invite_link_info->chat_id = ChatId();
+      invite_link_info->channel_id = ChannelId();
+      invite_link_info->title = chat_invite->title_;
+      invite_link_info->photo = get_dialog_photo(td_->file_manager_.get(), std::move(chat_invite->photo_));
+      invite_link_info->participant_count = chat_invite->participants_count_;
+      invite_link_info->participant_user_ids.clear();
+      for (auto &user : chat_invite->participants_) {
+        auto user_id = get_user_id(user);
+        if (!user_id.is_valid()) {
+          LOG(ERROR) << "Receive invalid " << user_id;
+        } else {
+          on_get_user(std::move(user));
+        }
+        invite_link_info->participant_user_ids.push_back(user_id);
+      }
+      invite_link_info->is_chat = (chat_invite->flags_ & CHAT_INVITE_FLAG_IS_CHANNEL) == 0;
+      invite_link_info->is_channel = (chat_invite->flags_ & CHAT_INVITE_FLAG_IS_CHANNEL) != 0;
+
+      bool is_broadcast = (chat_invite->flags_ & CHAT_INVITE_FLAG_IS_BROADCAST) != 0;
+      bool is_public = (chat_invite->flags_ & CHAT_INVITE_FLAG_IS_PUBLIC) != 0;
+      bool is_megagroup = (chat_invite->flags_ & CHAT_INVITE_FLAG_IS_MEGAGROUP) != 0;
+
+      if (!invite_link_info->is_channel) {
+        if (is_broadcast || is_public || is_megagroup) {
+          LOG(ERROR) << "Receive wrong chat invite: " << to_string(chat_invite);
+          is_public = is_megagroup = false;
+        }
+      } else {
+        LOG_IF(ERROR, is_broadcast == is_megagroup) << "Receive wrong chat invite: " << to_string(chat_invite);
+      }
+
+      invite_link_info->is_public = is_public;
+      invite_link_info->is_megagroup = is_megagroup;
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+}
+
+bool ContactsManager::is_valid_invite_link(const string &invite_link) {
+  return !get_dialog_invite_link_hash(invite_link).empty();
+}
+
+Slice ContactsManager::get_dialog_invite_link_hash(const string &invite_link) {
+  auto lower_cased_invite_link_str = to_lower(invite_link);
+  Slice lower_cased_invite_link = lower_cased_invite_link_str;
+  size_t offset = 0;
+  if (begins_with(lower_cased_invite_link, "https://")) {
+    offset = 8;
+  } else if (begins_with(lower_cased_invite_link, "http://")) {
+    offset = 7;
+  }
+  lower_cased_invite_link.remove_prefix(offset);
+
+  for (auto &url : INVITE_LINK_URLS) {
+    if (begins_with(lower_cased_invite_link, url)) {
+      return Slice(invite_link).substr(url.size() + offset);
+    }
+  }
+  return Slice();
+}
+
+bool ContactsManager::update_invite_link(string &invite_link,
+                                         tl_object_ptr<telegram_api::ExportedChatInvite> &&invite_link_ptr) {
+  string new_invite_link;
+  if (invite_link_ptr != nullptr) {
+    switch (invite_link_ptr->get_id()) {
+      case telegram_api::chatInviteEmpty::ID:
+        // link is empty
+        break;
+      case telegram_api::chatInviteExported::ID: {
+        auto chat_invite_exported = move_tl_object_as<telegram_api::chatInviteExported>(invite_link_ptr);
+        new_invite_link = std::move(chat_invite_exported->link_);
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+  }
+
+  if (new_invite_link != invite_link) {
+    if (!invite_link.empty()) {
+      invite_link_infos_.erase(invite_link);
+    }
+    LOG_IF(ERROR, !new_invite_link.empty() && !is_valid_invite_link(new_invite_link))
+        << "Unsupported invite link " << new_invite_link;
+
+    invite_link = std::move(new_invite_link);
+    return true;
+  }
+  return false;
+}
+
+void ContactsManager::invalidate_invite_link(const string &invite_link) {
+  invite_link_infos_.erase(invite_link);
+}
+
+void ContactsManager::repair_chat_participants(ChatId chat_id) {
+  send_get_chat_full_query(chat_id, Auto());
+}
+
+void ContactsManager::on_update_chat_add_user(ChatId chat_id, UserId inviter_user_id, UserId user_id, int32 date,
+                                              int32 version) {
+  if (!chat_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << chat_id;
+    return;
+  }
+  if (!have_user(user_id)) {
+    LOG(ERROR) << "Can't find " << user_id;
+    return;
+  }
+  if (!have_user(inviter_user_id)) {
+    LOG(ERROR) << "Can't find " << inviter_user_id;
+    return;
+  }
+  LOG(INFO) << "Receive updateChatParticipantAdd to " << chat_id << " with " << user_id << " invited by "
+            << inviter_user_id << " at " << date << " with version " << version;
+
+  ChatFull *chat_full = get_chat_full(chat_id);
+  if (chat_full == nullptr) {
+    LOG(INFO) << "Ignoring update about members of " << chat_id;
+    return;
+  }
+  auto c = get_chat(chat_id);
+  if (c == nullptr) {
+    LOG(ERROR) << "Receive updateChatParticipantAdd for unknown " << chat_id << ". Couldn't apply it";
+    repair_chat_participants(chat_id);
+    return;
+  }
+  if (c->left) {
+    // possible if updates come out of order
+    LOG(WARNING) << "Receive updateChatParticipantAdd for left " << chat_id << ". Couldn't apply it";
+
+    repair_chat_participants(chat_id);  // just in case
+    return;
+  }
+  if (on_update_chat_full_participants_short(chat_full, chat_id, version)) {
+    for (auto &participant : chat_full->participants) {
+      if (participant.user_id == user_id) {
+        if (participant.inviter_user_id != inviter_user_id) {
+          LOG(ERROR) << user_id << " was readded to " << chat_id << " by " << inviter_user_id
+                     << ", previously invited by " << participant.inviter_user_id;
+          participant.inviter_user_id = inviter_user_id;
+          participant.joined_date = date;
+          repair_chat_participants(chat_id);
+        } else {
+          // Possible if update comes twice
+          LOG(INFO) << user_id << " was readded to " << chat_id;
+        }
+        return;
+      }
+    }
+    chat_full->participants.push_back(DialogParticipant{user_id, inviter_user_id, date,
+                                                        user_id == chat_full->creator_user_id
+                                                            ? DialogParticipantStatus::Creator(true)
+                                                            : DialogParticipantStatus::Member()});
+    chat_full->is_changed = true;
+    update_chat_full(chat_full, chat_id);
+
+    // Chat is already updated
+    if (chat_full->version == c->version &&
+        narrow_cast<int32>(chat_full->participants.size()) != c->participant_count) {
+      LOG(ERROR) << "Number of members of " << chat_id << " with version " << c->version << " is "
+                 << c->participant_count << " but there are " << chat_full->participants.size()
+                 << " members in the ChatFull";
+      repair_chat_participants(chat_id);
+    }
+  }
+}
+
+void ContactsManager::on_update_chat_edit_administrator(ChatId chat_id, UserId user_id, bool is_administrator,
+                                                        int32 version) {
+  if (!chat_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << chat_id;
+    return;
+  }
+  if (!have_user(user_id)) {
+    LOG(ERROR) << "Can't find " << user_id;
+    return;
+  }
+  LOG(INFO) << "Receive updateChatParticipantAdmin in " << chat_id << " with " << user_id << ", administrator rights "
+            << (is_administrator ? "enabled" : "disabled") << " with version " << version;
+
+  auto c = get_chat_force(chat_id);
+  if (c == nullptr) {
+    LOG(INFO) << "Ignoring update about members of unknown " << chat_id;
+    return;
+  }
+
+  if (c->left) {
+    // possible if updates come out of order
+    LOG(WARNING) << "Receive updateChatParticipantAdmin for left " << chat_id << ". Couldn't apply it";
+
+    repair_chat_participants(chat_id);  // just in case
+    return;
+  }
+  if (version <= -1) {
+    LOG(ERROR) << "Receive wrong version " << version << " for " << chat_id;
+    return;
+  }
+  CHECK(c->version >= 0);
+
+  if (version > c->version) {
+    if (version != c->version + 1) {
+      LOG(ERROR) << "Administrators of " << chat_id << " with version " << c->version
+                 << " has changed but new version is " << version;
+      repair_chat_participants(chat_id);
+      return;
+    }
+
+    c->version = version;
+    c->is_changed = true;
+    if (user_id == get_my_id("on_update_chat_edit_administrator")) {
+      on_update_chat_rights(c, chat_id, c->is_creator, is_administrator, c->everyone_is_administrator);
+    }
+    update_chat(c, chat_id);
+  }
+
+  ChatFull *chat_full = get_chat_full(chat_id);
+  if (chat_full != nullptr) {
+    if (chat_full->version + 1 == version) {
+      for (auto &participant : chat_full->participants) {
+        if (participant.user_id == user_id) {
+          participant.status = is_administrator ? DialogParticipantStatus::GroupAdministrator(c->is_creator)
+                                                : DialogParticipantStatus::Member();
+          chat_full->is_changed = true;
+          update_chat_full(chat_full, chat_id);
+          return;
+        }
+      }
+    }
+
+    // can't find chat member or version have increased too much
+    repair_chat_participants(chat_id);
+  }
+}
+
+void ContactsManager::on_update_chat_delete_user(ChatId chat_id, UserId user_id, int32 version) {
+  if (!chat_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << chat_id;
+    return;
+  }
+  if (!have_user(user_id)) {
+    LOG(ERROR) << "Can't find " << user_id;
+    return;
+  }
+  LOG(INFO) << "Receive updateChatParticipantDelete from " << chat_id << " with " << user_id << " and version "
+            << version;
+
+  ChatFull *chat_full = get_chat_full(chat_id);
+  if (chat_full == nullptr) {
+    LOG(INFO) << "Ignoring update about members of " << chat_id;
+    return;
+  }
+  const Chat *c = get_chat_force(chat_id);
+  if (c == nullptr) {
+    LOG(ERROR) << "Receive updateChatParticipantDelete for unknown " << chat_id;
+    repair_chat_participants(chat_id);
+    return;
+  }
+  if (user_id == get_my_id("on_update_chat_delete_user")) {
+    LOG_IF(WARNING, !c->left) << "User was removed from " << chat_id
+                              << " but it is not left the group. Possible if updates comes out of order";
+    return;
+  }
+  if (c->left) {
+    // possible if updates come out of order
+    LOG(INFO) << "Receive updateChatParticipantDelete for left " << chat_id;
+
+    repair_chat_participants(chat_id);
+    return;
+  }
+  if (on_update_chat_full_participants_short(chat_full, chat_id, version)) {
+    for (size_t i = 0; i < chat_full->participants.size(); i++) {
+      if (chat_full->participants[i].user_id == user_id) {
+        chat_full->participants[i] = chat_full->participants.back();
+        chat_full->participants.resize(chat_full->participants.size() - 1);
+        chat_full->is_changed = true;
+        update_chat_full(chat_full, chat_id);
+
+        if (static_cast<int>(chat_full->participants.size()) != c->participant_count) {
+          repair_chat_participants(chat_id);
+        }
+        return;
+      }
+    }
+    LOG(ERROR) << "Can't find group member " << user_id << " in " << chat_id << " to delete him";
+    repair_chat_participants(chat_id);
+  }
+}
+
+void ContactsManager::on_update_chat_everyone_is_administrator(ChatId chat_id, bool everyone_is_administrator,
+                                                               int32 version) {
+  if (!chat_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << chat_id;
+    return;
+  }
+  LOG(INFO) << "Receive updateChatAdmins in " << chat_id << " with version " << version
+            << " and everyone_is_administrator = " << everyone_is_administrator << ". Current version is " << version;
+
+  auto c = get_chat_force(chat_id);
+  if (c == nullptr) {
+    LOG(INFO) << "Ignoring update about unknown " << chat_id;
+    return;
+  }
+
+  if (c->left) {
+    // possible if updates come out of order
+    LOG(WARNING) << "Receive updateChatAdmins for left " << chat_id << ". Couldn't apply it";
+
+    repair_chat_participants(chat_id);  // just in case
+    return;
+  }
+  if (version <= -1) {
+    LOG(ERROR) << "Receive wrong version " << version << " for " << chat_id;
+    return;
+  }
+  CHECK(c->version >= 0);
+
+  if (version > c->version) {
+    if (version != c->version + 1) {
+      LOG(WARNING) << "Anyone can edit of " << chat_id << " with version " << c->version
+                   << " has changed but new version is " << version;
+      repair_chat_participants(chat_id);
+      return;
+    }
+
+    LOG_IF(ERROR, everyone_is_administrator == c->everyone_is_administrator)
+        << "Receive updateChatAdmins in " << chat_id << " with version " << version
+        << " and everyone_is_administrator = " << everyone_is_administrator
+        << ", but everyone_is_administrator is not changed. Current version is " << c->version;
+    c->version = version;
+    c->is_changed = true;
+    on_update_chat_rights(c, chat_id, c->is_creator, c->is_administrator, everyone_is_administrator);
+    update_chat(c, chat_id);
+  }
+}
+
+void ContactsManager::on_update_chat_left(Chat *c, ChatId chat_id, bool left, bool kicked) {
+  if (c->left != left || c->kicked != kicked) {
+    c->left = left;
+    c->kicked = kicked;
+
+    if (c->left) {
+      c->participant_count = 0;
+      c->version = -1;
+
+      invalidate_chat_full(chat_id);
+    }
+
+    c->need_send_update = true;
+  }
+}
+
+void ContactsManager::on_update_chat_rights(Chat *c, ChatId chat_id, bool is_creator, bool is_administrator,
+                                            bool everyone_is_administrator) {
+  if (c->is_creator != is_creator || c->is_administrator != is_administrator ||
+      c->everyone_is_administrator != everyone_is_administrator) {
+    c->is_creator = is_creator;
+    c->is_administrator = is_administrator;
+    c->everyone_is_administrator = everyone_is_administrator;
+    c->can_edit = is_creator || is_administrator || everyone_is_administrator;
+    c->need_send_update = true;
+  }
+}
+
+void ContactsManager::on_update_chat_participant_count(Chat *c, ChatId chat_id, int32 participant_count, int32 version,
+                                                       const string &debug_str) {
+  if (version <= -1) {
+    LOG(ERROR) << "Receive wrong version " << version << " from " << debug_str;
+    return;
+  }
+
+  if (version < c->version) {
+    // some outdated data
+    LOG(INFO) << "Receive member count of " << chat_id << " with version " << version << " from " << debug_str
+              << ", but current version is " << c->version;
+    return;
+  }
+
+  if (c->participant_count != participant_count) {
+    if (version == c->version) {
+      // version is not changed when deleted user is removed from the chat
+      LOG_IF(ERROR, c->participant_count != participant_count + 1)
+          << "Member count of " << chat_id << " has changed from " << c->participant_count << " to "
+          << participant_count << ", but version " << c->version << " remains unchanged in " << debug_str;
+      repair_chat_participants(chat_id);
+    }
+
+    c->participant_count = participant_count;
+    c->version = version;
+    c->need_send_update = true;
+    return;
+  }
+
+  if (version > c->version) {
+    c->version = version;
+    c->is_changed = true;
+  }
+}
+
+void ContactsManager::on_update_chat_photo(Chat *c, ChatId chat_id,
+                                           tl_object_ptr<telegram_api::ChatPhoto> &&chat_photo_ptr) {
+  DialogPhoto new_chat_photo = get_dialog_photo(td_->file_manager_.get(), std::move(chat_photo_ptr));
+
+  if (new_chat_photo != c->photo) {
+    c->photo = new_chat_photo;
+    c->is_photo_changed = true;
+    c->is_changed = true;
+  }
+}
+
+void ContactsManager::on_update_chat_title(Chat *c, ChatId chat_id, string &&title) {
+  if (c->title != title) {
+    c->title = std::move(title);
+    c->is_title_changed = true;
+    c->is_changed = true;
+  }
+}
+
+void ContactsManager::on_update_chat_active(Chat *c, ChatId chat_id, bool is_active) {
+  if (c->is_active != is_active) {
+    c->is_active = is_active;
+    c->need_send_update = true;
+  }
+}
+
+void ContactsManager::on_update_chat_migrated_to_channel_id(Chat *c, ChatId chat_id, ChannelId migrated_to_channel_id) {
+  if (c->migrated_to_channel_id != migrated_to_channel_id && migrated_to_channel_id.is_valid()) {
+    LOG_IF(ERROR, c->migrated_to_channel_id.is_valid())
+        << "Group upgraded to supergroup has changed from " << c->migrated_to_channel_id << " to "
+        << migrated_to_channel_id;
+    c->migrated_to_channel_id = migrated_to_channel_id;
+    c->need_send_update = true;
+  }
+}
+
+bool ContactsManager::on_update_chat_full_participants_short(ChatFull *chat_full, ChatId chat_id, int32 version) {
+  if (version <= -1) {
+    LOG(ERROR) << "Receive wrong version " << version << " for " << chat_id;
+    return false;
+  }
+  if (chat_full->version == -1) {
+    // chat members are unknown, nothing to update
+    return false;
+  }
+
+  if (chat_full->version + 1 == version) {
+    chat_full->version = version;
+    return true;
+  }
+
+  LOG(ERROR) << "Member count of " << chat_id << " with version " << chat_full->version
+             << " has changed but new version is " << version;
+  repair_chat_participants(chat_id);
+  return false;
+}
+
+void ContactsManager::on_update_chat_full_participants(ChatFull *chat_full, ChatId chat_id,
+                                                       vector<DialogParticipant> participants, int32 version) {
+  if (version <= -1) {
+    LOG(ERROR) << "Receive members with wrong version " << version;
+    return;
+  }
+
+  if (version < chat_full->version) {
+    // some outdated data
+    LOG(WARNING) << "Receive members of " << chat_id << " with version " << version << " but current version is "
+                 << chat_full->version;
+    return;
+  }
+
+  if (chat_full->participants.size() != participants.size() && version == chat_full->version) {
+    LOG(INFO) << "Members of " << chat_id << " has changed";
+    // this is possible in very rare situations
+    repair_chat_participants(chat_id);
+  }
+
+  chat_full->participants = std::move(participants);
+  chat_full->version = version;
+  chat_full->is_changed = true;
+}
+
+void ContactsManager::invalidate_chat_full(ChatId chat_id) {
+  ChatFull *chat_full = get_chat_full(chat_id);
+  if (chat_full == nullptr) {
+    return;
+  }
+
+  LOG(INFO) << "Invalidate groupFull of " << chat_id;
+  //chat_full->creator_user_id = UserId();
+  chat_full->participants.clear();
+  chat_full->version = -1;
+  update_invite_link(chat_full->invite_link, nullptr);
+  chat_full->is_changed = true;
+  update_chat_full(chat_full, chat_id);
+}
+
+void ContactsManager::on_update_channel_photo(Channel *c, ChannelId channel_id,
+                                              tl_object_ptr<telegram_api::ChatPhoto> &&chat_photo_ptr) {
+  DialogPhoto new_chat_photo = get_dialog_photo(td_->file_manager_.get(), std::move(chat_photo_ptr));
+
+  if (new_chat_photo != c->photo) {
+    c->photo = new_chat_photo;
+    c->is_photo_changed = true;
+    c->is_changed = true;
+  }
+}
+
+void ContactsManager::on_update_channel_title(Channel *c, ChannelId channel_id, string &&title) {
+  if (c->title != title) {
+    c->title = std::move(title);
+    c->is_title_changed = true;
+    c->is_changed = true;
+  }
+}
+
+void ContactsManager::on_update_channel_status(Channel *c, ChannelId channel_id, DialogParticipantStatus &&status) {
+  if (c->status != status) {
+    LOG(INFO) << "Update " << channel_id << " status from " << c->status << " to " << status;
+    c->status = status;
+    c->is_status_changed = true;
+    c->need_send_update = true;
+    invalidate_channel_full(channel_id);
+  }
+}
+
+void ContactsManager::on_update_channel_username(ChannelId channel_id, string &&username) {
+  if (!channel_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << channel_id;
+    return;
+  }
+
+  Channel *c = get_channel_force(channel_id);
+  if (c != nullptr) {
+    on_update_channel_username(c, channel_id, std::move(username));
+    update_channel(c, channel_id);
+  } else {
+    LOG(ERROR) << "Ignore update channel username about unknown " << channel_id;
+  }
+}
+
+void ContactsManager::on_update_channel_username(Channel *c, ChannelId channel_id, string &&username) {
+  td_->messages_manager_->on_dialog_username_updated(DialogId(channel_id), c->username, username);
+  if (c->username != username) {
+    if (c->username.empty() || username.empty()) {
+      // moving channel from private to public can change availability of chat members
+      invalidate_channel_full(channel_id);
+    }
+
+    c->username = std::move(username);
+    c->is_username_changed = true;
+    c->need_send_update = true;
+  }
+}
+
+void ContactsManager::on_update_channel_full_pinned_message(ChannelFull *channel_full, MessageId message_id) {
+  if (!message_id.is_valid() && message_id != MessageId()) {
+    LOG(ERROR) << "Receive " << message_id << " as pinned message";
+    return;
+  }
+  CHECK(channel_full != nullptr);
+
+  if (channel_full->pinned_message_id != message_id) {
+    channel_full->pinned_message_id = message_id;
+    channel_full->is_changed = true;
+  }
+}
+
+void ContactsManager::on_update_channel_description(ChannelId channel_id, string &&description) {
+  if (!channel_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << channel_id;
+    return;
+  }
+
+  auto channel_full = get_channel_full(channel_id);
+  if (channel_full == nullptr) {
+    return;
+  }
+  if (channel_full->description != description) {
+    channel_full->description = std::move(description);
+    channel_full->is_changed = true;
+    update_channel_full(channel_full, channel_id);
+  }
+}
+
+void ContactsManager::on_update_channel_sticker_set(ChannelId channel_id, int64 sticker_set_id) {
+  if (!channel_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << channel_id;
+    return;
+  }
+
+  auto channel_full = get_channel_full(channel_id);
+  if (channel_full == nullptr) {
+    return;
+  }
+  if (channel_full->sticker_set_id != sticker_set_id) {
+    channel_full->sticker_set_id = sticker_set_id;
+    channel_full->is_changed = true;
+    update_channel_full(channel_full, channel_id);
+  }
+}
+
+void ContactsManager::on_update_channel_pinned_message(ChannelId channel_id, MessageId message_id) {
+  if (!channel_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << channel_id;
+    return;
+  }
+
+  auto channel_full = get_channel_full(channel_id);
+  if (channel_full == nullptr) {
+    return;
+  }
+  on_update_channel_full_pinned_message(channel_full, message_id);
+  update_channel_full(channel_full, channel_id);
+}
+
+void ContactsManager::on_update_channel_is_all_history_available(ChannelId channel_id, bool is_all_history_available) {
+  if (!channel_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << channel_id;
+    return;
+  }
+
+  auto channel_full = get_channel_full(channel_id);
+  if (channel_full == nullptr) {
+    return;
+  }
+  if (channel_full->is_all_history_available != is_all_history_available) {
+    channel_full->is_all_history_available = is_all_history_available;
+    channel_full->is_changed = true;
+    update_channel_full(channel_full, channel_id);
+  }
+}
+
+void ContactsManager::update_contacts_hints(const User *u, UserId user_id, bool from_database) {
+  bool is_contact = u->outbound == LinkState::Contact && user_id != get_my_id("update_contacts_hints");
+  if (td_->auth_manager_->is_bot()) {
+    LOG_IF(ERROR, is_contact) << "Bot has " << user_id << " in the contacts list";
+    return;
+  }
+
+  int64 key = user_id.get();
+  string old_value = contacts_hints_.key_to_string(key);
+  string new_value = is_contact ? u->first_name + " " + u->last_name + " " + u->username : "";
+
+  if (new_value != old_value) {
+    if (is_contact) {
+      contacts_hints_.add(key, new_value);
+    } else {
+      contacts_hints_.remove(key);
+    }
+  }
+
+  if (G()->parameters().use_chat_info_db) {
+    // update contacts database
+    if (!are_contacts_loaded_) {
+      if (!from_database && load_contacts_queries_.empty()) {
+        search_contacts("", std::numeric_limits<int32>::max(), Auto());
+      }
+    } else {
+      if (old_value.empty() == is_contact) {
+        save_contacts_to_database();
+      }
+    }
+  }
+}
+
+bool ContactsManager::have_user(UserId user_id) const {
+  auto u = get_user(user_id);
+  return u != nullptr && u->is_received;
+}
+
+bool ContactsManager::have_min_user(UserId user_id) const {
+  return users_.count(user_id) > 0;
+}
+
+bool ContactsManager::is_user_deleted(UserId user_id) const {
+  auto u = get_user(user_id);
+  return u == nullptr || u->is_deleted;
+}
+
+bool ContactsManager::is_user_bot(UserId user_id) const {
+  auto u = get_user(user_id);
+  return u != nullptr && !u->is_deleted && u->is_bot;
+}
+
+Result<BotData> ContactsManager::get_bot_data(UserId user_id) const {
+  auto p = users_.find(user_id);
+  if (p == users_.end()) {
+    return Status::Error(5, "Bot not found");
+  }
+
+  auto bot = &p->second;
+  if (!bot->is_bot) {
+    return Status::Error(5, "User is not a bot");
+  }
+  if (bot->is_deleted) {
+    return Status::Error(5, "Bot is deleted");
+  }
+  if (!bot->is_received) {
+    return Status::Error(5, "Bot is inaccessible");
+  }
+
+  BotData bot_data;
+  bot_data.username = bot->username;
+  bot_data.can_join_groups = bot->can_join_groups;
+  bot_data.can_read_all_group_messages = bot->can_read_all_group_messages;
+  bot_data.is_inline = bot->is_inline_bot;
+  bot_data.need_location = bot->need_location_bot;
+  return bot_data;
+}
+
+const ContactsManager::User *ContactsManager::get_user(UserId user_id) const {
+  auto p = users_.find(user_id);
+  if (p == users_.end()) {
+    return nullptr;
+  } else {
+    return &p->second;
+  }
+}
+
+ContactsManager::User *ContactsManager::get_user(UserId user_id) {
+  auto p = users_.find(user_id);
+  if (p == users_.end()) {
+    return nullptr;
+  } else {
+    return &p->second;
+  }
+}
+
+void ContactsManager::send_get_me_query(Td *td, Promise<Unit> &&promise) {
+  vector<tl_object_ptr<telegram_api::InputUser>> users;
+  users.push_back(make_tl_object<telegram_api::inputUserSelf>());
+  td->create_handler<GetUsersQuery>(std::move(promise))->send(std::move(users));
+}
+
+UserId ContactsManager::get_me(Promise<Unit> &&promise) {
+  auto my_id = get_my_id("get_me");
+  if (!have_user_force(my_id)) {
+    send_get_me_query(td_, std::move(promise));
+    return UserId();
+  }
+
+  promise.set_value(Unit());
+  return my_id;
+}
+
+bool ContactsManager::get_user(UserId user_id, int left_tries, Promise<Unit> &&promise) {
+  if (!user_id.is_valid()) {
+    promise.set_error(Status::Error(6, "Invalid user id"));
+    return false;
+  }
+
+  // TODO support loading user from database and merging it with min-user in memory
+  if (!have_min_user(user_id)) {
+    // TODO UserLoader
+    if (left_tries > 2 && G()->parameters().use_chat_info_db) {
+      send_closure_later(actor_id(this), &ContactsManager::load_user_from_database, nullptr, user_id,
+                         std::move(promise));
+      return false;
+    }
+    auto input_user = get_input_user(user_id);
+    if (left_tries == 1 || input_user == nullptr) {
+      promise.set_error(Status::Error(6, "User not found"));
+      return false;
+    }
+
+    vector<tl_object_ptr<telegram_api::InputUser>> users;
+    users.push_back(std::move(input_user));
+    td_->create_handler<GetUsersQuery>(std::move(promise))->send(std::move(users));
+    return false;
+  }
+
+  promise.set_value(Unit());
+  return true;
+}
+
+ContactsManager::User *ContactsManager::add_user(UserId user_id) {
+  CHECK(user_id.is_valid());
+  return &users_[user_id];
+}
+
+const ContactsManager::UserFull *ContactsManager::get_user_full(UserId user_id) const {
+  auto p = users_full_.find(user_id);
+  if (p == users_full_.end()) {
+    return nullptr;
+  } else {
+    return &p->second;
+  }
+}
+
+ContactsManager::UserFull *ContactsManager::get_user_full(UserId user_id) {
+  auto p = users_full_.find(user_id);
+  if (p == users_full_.end()) {
+    return nullptr;
+  } else {
+    return &p->second;
+  }
+}
+
+bool ContactsManager::get_user_full(UserId user_id, Promise<Unit> &&promise) {
+  auto user = get_user(user_id);
+  if (user == nullptr) {
+    promise.set_error(Status::Error(6, "User not found"));
+    return false;
+  }
+
+  auto user_full = get_user_full(user_id);
+  if (user_full == nullptr || !user_full->is_inited) {
+    auto input_user = get_input_user(user_id);
+    if (input_user == nullptr) {
+      promise.set_error(Status::Error(6, "Can't get info about unaccessible user"));
+      return false;
+    }
+
+    send_get_user_full_query(user_id, std::move(input_user), std::move(promise));
+    return false;
+  }
+  if (user_full->is_expired() || user_full->is_bot_info_expired(user->bot_info_version)) {
+    auto input_user = get_input_user(user_id);
+    CHECK(input_user != nullptr);
+    if (td_->auth_manager_->is_bot()) {
+      send_get_user_full_query(user_id, std::move(input_user), std::move(promise));
+      return false;
+    } else {
+      send_get_user_full_query(user_id, std::move(input_user), Auto());
+    }
+  }
+
+  promise.set_value(Unit());
+  return true;
+}
+
+void ContactsManager::send_get_user_full_query(UserId user_id, tl_object_ptr<telegram_api::InputUser> &&input_user,
+                                               Promise<Unit> &&promise) {
+  auto &promises = get_user_full_queries_[user_id];
+  promises.push_back(std::move(promise));
+  if (promises.size() != 1) {
+    // query has already been sent, just wait for the result
+    return;
+  }
+
+  td_->create_handler<GetFullUserQuery>()->send(user_id, std::move(input_user));
+}
+
+void ContactsManager::on_get_user_full_success(UserId user_id) {
+  auto it = get_user_full_queries_.find(user_id);
+  CHECK(it != get_user_full_queries_.end());
+  CHECK(!it->second.empty());
+  auto promises = std::move(it->second);
+  get_user_full_queries_.erase(it);
+
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+void ContactsManager::on_get_user_full_fail(UserId user_id, Status &&error) {
+  auto it = get_user_full_queries_.find(user_id);
+  CHECK(it != get_user_full_queries_.end());
+  CHECK(!it->second.empty());
+  auto promises = std::move(it->second);
+  get_user_full_queries_.erase(it);
+
+  for (auto &promise : promises) {
+    promise.set_error(error.clone());
+  }
+}
+
+std::pair<int32, vector<const Photo *>> ContactsManager::get_user_profile_photos(UserId user_id, int32 offset,
+                                                                                 int32 limit, Promise<Unit> &&promise) {
+  std::pair<int32, vector<const Photo *>> result;
+  result.first = -1;
+
+  if (offset < 0) {
+    promise.set_error(Status::Error(3, "Parameter offset must be non-negative"));
+    return result;
+  }
+  if (limit <= 0) {
+    promise.set_error(Status::Error(3, "Parameter limit must be positive"));
+    return result;
+  }
+  if (limit > MAX_GET_PROFILE_PHOTOS) {
+    limit = MAX_GET_PROFILE_PHOTOS;
+  }
+
+  auto input_user = get_input_user(user_id);
+  if (input_user == nullptr) {
+    promise.set_error(Status::Error(6, "User not found"));
+    return result;
+  }
+
+  auto user_full = &users_full_[user_id];
+  if (user_full->getting_photos_now) {
+    promise.set_error(Status::Error(400, "Request for new profile photos has already been sent"));
+    return result;
+  }
+
+  if (user_full->photo_count != -1) {  // know photo count
+    CHECK(user_full->photos_offset != -1);
+    result.first = user_full->photo_count;
+
+    if (offset >= user_full->photo_count) {
+      // offset if too big
+      promise.set_value(Unit());
+      return result;
+    }
+
+    if (limit > user_full->photo_count - offset) {
+      limit = user_full->photo_count - offset;
+    }
+
+    int32 cache_begin = user_full->photos_offset;
+    int32 cache_end = cache_begin + narrow_cast<int32>(user_full->photos.size());
+    if (cache_begin <= offset && offset + limit <= cache_end) {
+      // answer query from cache
+      for (int i = 0; i < limit; i++) {
+        result.second.push_back(&user_full->photos[i + offset - cache_begin]);
+      }
+      promise.set_value(Unit());
+      return result;
+    }
+
+    if (cache_begin <= offset && offset < cache_end) {
+      // adjust offset to the end of cache
+      limit = offset + limit - cache_end;
+      offset = cache_end;
+    }
+  }
+
+  user_full->getting_photos_now = true;
+
+  if (limit < MAX_GET_PROFILE_PHOTOS / 5) {
+    limit = MAX_GET_PROFILE_PHOTOS / 5;  // make limit reasonable
+  }
+
+  td_->create_handler<GetUserPhotosQuery>(std::move(promise))->send(user_id, std::move(input_user), offset, limit);
+  return result;
+}
+
+bool ContactsManager::have_chat(ChatId chat_id) const {
+  return chats_.count(chat_id) > 0;
+}
+
+const ContactsManager::Chat *ContactsManager::get_chat(ChatId chat_id) const {
+  auto p = chats_.find(chat_id);
+  if (p == chats_.end()) {
+    return nullptr;
+  } else {
+    return &p->second;
+  }
+}
+
+ContactsManager::Chat *ContactsManager::get_chat(ChatId chat_id) {
+  auto p = chats_.find(chat_id);
+  if (p == chats_.end()) {
+    return nullptr;
+  } else {
+    return &p->second;
+  }
+}
+
+ContactsManager::Chat *ContactsManager::add_chat(ChatId chat_id) {
+  CHECK(chat_id.is_valid());
+  return &chats_[chat_id];
+}
+
+bool ContactsManager::get_chat(ChatId chat_id, int left_tries, Promise<Unit> &&promise) {
+  if (!chat_id.is_valid()) {
+    promise.set_error(Status::Error(6, "Invalid basic group id"));
+    return false;
+  }
+
+  if (!have_chat(chat_id)) {
+    if (left_tries > 2 && G()->parameters().use_chat_info_db) {
+      send_closure_later(actor_id(this), &ContactsManager::load_chat_from_database, nullptr, chat_id,
+                         std::move(promise));
+      return false;
+    }
+
+    if (left_tries > 1) {
+      td_->create_handler<GetChatsQuery>(std::move(promise))->send(vector<int32>{chat_id.get()});
+      return false;
+    }
+
+    promise.set_error(Status::Error(6, "Group not found"));
+    return false;
+  }
+
+  promise.set_value(Unit());
+  return true;
+}
+
+const ContactsManager::ChatFull *ContactsManager::get_chat_full(ChatId chat_id) const {
+  auto p = chats_full_.find(chat_id);
+  if (p == chats_full_.end()) {
+    return nullptr;
+  } else {
+    return &p->second;
+  }
+}
+
+ContactsManager::ChatFull *ContactsManager::get_chat_full(ChatId chat_id) {
+  auto p = chats_full_.find(chat_id);
+  if (p == chats_full_.end()) {
+    return nullptr;
+  } else {
+    return &p->second;
+  }
+}
+
+bool ContactsManager::is_chat_full_outdated(ChatFull *chat_full, Chat *c, ChatId chat_id) {
+  CHECK(c != nullptr);
+  CHECK(chat_full != nullptr);
+  if (chat_full->version != c->version) {
+    LOG(INFO) << "Have outdated ChatFull " << chat_id << " with current version "
+              << (chat_full ? chat_full->version : -123456789) << " and chat version " << c->version;
+    return true;
+  }
+
+  for (auto &participant : chat_full->participants) {
+    auto user = get_user(participant.user_id);
+    if (user != nullptr && user->bot_info_version != -1) {
+      auto user_full = get_user_full(participant.user_id);
+      if (user_full == nullptr || user_full->is_bot_info_expired(user->bot_info_version)) {
+        LOG(INFO) << "Have outdated botInfo for " << participant.user_id << " with version "
+                  << (user_full && user_full->bot_info ? user_full->bot_info->version : -123456789)
+                  << ", but current version is " << user->bot_info_version;
+        return true;
+      }
+    }
+  }
+
+  return false;
+}
+
+bool ContactsManager::get_chat_full(ChatId chat_id, Promise<Unit> &&promise) {
+  auto chat = get_chat(chat_id);
+  if (chat == nullptr) {
+    promise.set_error(Status::Error(6, "Group not found"));
+    return false;
+  }
+
+  auto chat_full = get_chat_full(chat_id);
+  if (chat_full == nullptr) {
+    LOG(INFO) << "Full " << chat_id << " not found";
+    send_get_chat_full_query(chat_id, std::move(promise));
+    return false;
+  }
+
+  if (is_chat_full_outdated(chat_full, chat, chat_id)) {
+    LOG(INFO) << "Have outdated full " << chat_id;
+    if (td_->auth_manager_->is_bot()) {
+      send_get_chat_full_query(chat_id, std::move(promise));
+      return false;
+    } else {
+      send_get_chat_full_query(chat_id, Auto());
+    }
+  }
+
+  promise.set_value(Unit());
+  return true;
+}
+
+void ContactsManager::send_get_chat_full_query(ChatId chat_id, Promise<Unit> &&promise) {
+  auto &promises = get_chat_full_queries_[chat_id];
+  promises.push_back(std::move(promise));
+  if (promises.size() != 1) {
+    // query has already been sent, just wait for the result
+    return;
+  }
+
+  td_->create_handler<GetFullChatQuery>()->send(chat_id);
+}
+
+void ContactsManager::on_get_chat_full_success(ChatId chat_id) {
+  auto it = get_chat_full_queries_.find(chat_id);
+  CHECK(it != get_chat_full_queries_.end());
+  CHECK(!it->second.empty());
+  auto promises = std::move(it->second);
+  get_chat_full_queries_.erase(it);
+
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+void ContactsManager::on_get_chat_full_fail(ChatId chat_id, Status &&error) {
+  auto it = get_chat_full_queries_.find(chat_id);
+  CHECK(it != get_chat_full_queries_.end());
+  CHECK(!it->second.empty());
+  auto promises = std::move(it->second);
+  get_chat_full_queries_.erase(it);
+
+  for (auto &promise : promises) {
+    promise.set_error(error.clone());
+  }
+}
+
+bool ContactsManager::get_chat_is_active(ChatId chat_id) const {
+  auto c = get_chat(chat_id);
+  if (c == nullptr) {
+    return false;
+  }
+  return c->is_active;
+}
+
+DialogParticipantStatus ContactsManager::get_chat_status(ChatId chat_id) const {
+  auto c = get_chat(chat_id);
+  if (c == nullptr) {
+    return DialogParticipantStatus::Banned(0);
+  }
+  return get_chat_status(c);
+}
+
+DialogParticipantStatus ContactsManager::get_chat_status(const Chat *c) {
+  if (c->kicked || !c->is_active) {
+    return DialogParticipantStatus::Banned(0);
+  }
+  if (c->left) {
+    return DialogParticipantStatus::Left();
+  }
+  if (c->is_creator) {
+    return DialogParticipantStatus::Creator(true);
+  }
+  if (c->can_edit) {
+    return DialogParticipantStatus::GroupAdministrator(false);
+  }
+  return DialogParticipantStatus::Member();
+}
+
+bool ContactsManager::is_appointed_chat_administrator(ChatId chat_id) const {
+  auto c = get_chat(chat_id);
+  if (c == nullptr) {
+    return false;
+  }
+  if (c->everyone_is_administrator) {
+    return c->is_creator;
+  } else {
+    return c->can_edit;
+  }
+}
+
+ChannelType ContactsManager::get_channel_type(ChannelId channel_id) const {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return ChannelType::Unknown;
+  }
+  return get_channel_type(c);
+}
+
+ChannelType ContactsManager::get_channel_type(const Channel *c) {
+  if (c->is_megagroup) {
+    return ChannelType::Megagroup;
+  }
+  return ChannelType::Broadcast;
+}
+
+int32 ContactsManager::get_channel_date(ChannelId channel_id) const {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return 0;
+  }
+  return c->date;
+}
+
+DialogParticipantStatus ContactsManager::get_channel_status(ChannelId channel_id) const {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return DialogParticipantStatus::Banned(0);
+  }
+  return get_channel_status(c);
+}
+
+DialogParticipantStatus ContactsManager::get_channel_status(const Channel *c) {
+  c->status.update_restrictions();
+  return c->status;
+}
+
+bool ContactsManager::get_channel_sign_messages(ChannelId channel_id) const {
+  auto c = get_channel(channel_id);
+  if (c == nullptr) {
+    return false;
+  }
+  return get_channel_sign_messages(c);
+}
+
+bool ContactsManager::get_channel_sign_messages(const Channel *c) {
+  return c->sign_messages;
+}
+
+bool ContactsManager::have_channel(ChannelId channel_id) const {
+  return channels_.count(channel_id) > 0;
+}
+
+bool ContactsManager::have_min_channel(ChannelId channel_id) const {
+  return min_channels_.count(channel_id) > 0;
+}
+
+const ContactsManager::Channel *ContactsManager::get_channel(ChannelId channel_id) const {
+  auto p = channels_.find(channel_id);
+  if (p == channels_.end()) {
+    return nullptr;
+  } else {
+    return &p->second;
+  }
+}
+
+ContactsManager::Channel *ContactsManager::get_channel(ChannelId channel_id) {
+  auto p = channels_.find(channel_id);
+  if (p == channels_.end()) {
+    return nullptr;
+  } else {
+    return &p->second;
+  }
+}
+
+ContactsManager::Channel *ContactsManager::add_channel(ChannelId channel_id) {
+  CHECK(channel_id.is_valid());
+  return &channels_[channel_id];
+}
+
+bool ContactsManager::get_channel(ChannelId channel_id, int left_tries, Promise<Unit> &&promise) {
+  if (!channel_id.is_valid()) {
+    promise.set_error(Status::Error(6, "Invalid supergroup id"));
+    return false;
+  }
+
+  if (!have_channel(channel_id)) {
+    if (left_tries > 2 && G()->parameters().use_chat_info_db) {
+      send_closure_later(actor_id(this), &ContactsManager::load_channel_from_database, nullptr, channel_id,
+                         std::move(promise));
+      return false;
+    }
+
+    if (left_tries > 1 && td_->auth_manager_->is_bot()) {
+      td_->create_handler<GetChannelsQuery>(std::move(promise))->send(get_input_channel(channel_id));
+      return false;
+    }
+
+    promise.set_error(Status::Error(6, "Supergroup not found"));
+    return false;
+  }
+
+  promise.set_value(Unit());
+  return true;
+}
+
+const ContactsManager::ChannelFull *ContactsManager::get_channel_full(ChannelId channel_id) const {
+  auto p = channels_full_.find(channel_id);
+  if (p == channels_full_.end()) {
+    return nullptr;
+  } else {
+    return &p->second;
+  }
+}
+
+ContactsManager::ChannelFull *ContactsManager::get_channel_full(ChannelId channel_id) {
+  auto p = channels_full_.find(channel_id);
+  if (p == channels_full_.end()) {
+    return nullptr;
+  }
+
+  auto channel_full = &p->second;
+  if (channel_full->is_expired()) {
+    auto input_channel = get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+    send_get_channel_full_query(channel_id, std::move(input_channel), Auto());
+  }
+
+  return channel_full;
+}
+
+bool ContactsManager::get_channel_full(ChannelId channel_id, Promise<Unit> &&promise) {
+  auto channel_full = get_channel_full(channel_id);
+  if (channel_full == nullptr) {
+    auto input_channel = get_input_channel(channel_id);
+    if (input_channel == nullptr) {
+      promise.set_error(Status::Error(6, "Supergroup not found"));
+      return false;
+    }
+
+    send_get_channel_full_query(channel_id, std::move(input_channel), std::move(promise));
+    return false;
+  }
+  if (channel_full->is_expired()) {
+    if (td_->auth_manager_->is_bot()) {
+      auto input_channel = get_input_channel(channel_id);
+      CHECK(input_channel != nullptr);
+      send_get_channel_full_query(channel_id, std::move(input_channel), std::move(promise));
+      return false;
+    } else {
+      // request has already been sent in get_channel_full
+      // send_get_channel_full_query(channel_id, std::move(input_channel), Auto());
+    }
+  }
+
+  promise.set_value(Unit());
+  return true;
+}
+
+void ContactsManager::send_get_channel_full_query(ChannelId channel_id,
+                                                  tl_object_ptr<telegram_api::InputChannel> &&input_channel,
+                                                  Promise<Unit> &&promise) {
+  auto &promises = get_channel_full_queries_[channel_id];
+  promises.push_back(std::move(promise));
+  if (promises.size() != 1) {
+    // query has already been sent, just wait for the result
+    return;
+  }
+
+  td_->create_handler<GetFullChannelQuery>()->send(channel_id, std::move(input_channel));
+}
+
+void ContactsManager::on_get_channel_full_success(ChannelId channel_id) {
+  auto it = get_channel_full_queries_.find(channel_id);
+  CHECK(it != get_channel_full_queries_.end());
+  CHECK(!it->second.empty());
+  auto promises = std::move(it->second);
+  get_channel_full_queries_.erase(it);
+
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+void ContactsManager::on_get_channel_full_fail(ChannelId channel_id, Status &&error) {
+  auto it = get_channel_full_queries_.find(channel_id);
+  CHECK(it != get_channel_full_queries_.end());
+  CHECK(!it->second.empty());
+  auto promises = std::move(it->second);
+  get_channel_full_queries_.erase(it);
+
+  for (auto &promise : promises) {
+    promise.set_error(error.clone());
+  }
+}
+
+bool ContactsManager::have_secret_chat(SecretChatId secret_chat_id) const {
+  return secret_chats_.count(secret_chat_id) > 0;
+}
+
+ContactsManager::SecretChat *ContactsManager::add_secret_chat(SecretChatId secret_chat_id) {
+  CHECK(secret_chat_id.is_valid());
+  return &secret_chats_[secret_chat_id];
+}
+
+const ContactsManager::SecretChat *ContactsManager::get_secret_chat(SecretChatId secret_chat_id) const {
+  auto it = secret_chats_.find(secret_chat_id);
+  if (it == secret_chats_.end()) {
+    return nullptr;
+  }
+  return &it->second;
+}
+
+ContactsManager::SecretChat *ContactsManager::get_secret_chat(SecretChatId secret_chat_id) {
+  auto it = secret_chats_.find(secret_chat_id);
+  if (it == secret_chats_.end()) {
+    return nullptr;
+  }
+  return &it->second;
+}
+
+bool ContactsManager::get_secret_chat(SecretChatId secret_chat_id, bool force, Promise<Unit> &&promise) {
+  if (!secret_chat_id.is_valid()) {
+    promise.set_error(Status::Error(6, "Invalid secret chat id"));
+    return false;
+  }
+
+  if (!have_secret_chat(secret_chat_id)) {
+    if (!force && G()->parameters().use_chat_info_db) {
+      send_closure_later(actor_id(this), &ContactsManager::load_secret_chat_from_database, nullptr, secret_chat_id,
+                         std::move(promise));
+      return false;
+    }
+
+    promise.set_error(Status::Error(6, "Secret chat not found"));
+    return false;
+  }
+
+  promise.set_value(Unit());
+  return true;
+}
+
+void ContactsManager::on_update_secret_chat(SecretChatId secret_chat_id, int64 access_hash, UserId user_id,
+                                            SecretChatState state, bool is_outbound, int32 ttl, int32 date,
+                                            string key_hash, int32 layer) {
+  LOG(INFO) << "Update " << secret_chat_id << " with " << user_id << " and access_hash " << access_hash;
+  auto *secret_chat = add_secret_chat(secret_chat_id);
+  if (access_hash != secret_chat->access_hash) {
+    secret_chat->access_hash = access_hash;
+    secret_chat->is_changed = true;
+  }
+  if (user_id.is_valid() && user_id != secret_chat->user_id) {
+    if (secret_chat->user_id.is_valid()) {
+      LOG(ERROR) << "Secret chat user has changed from " << secret_chat->user_id << " to " << user_id;
+      auto &old_secret_chat_ids = secret_chats_with_user_[secret_chat->user_id];
+      old_secret_chat_ids.erase(std::remove(old_secret_chat_ids.begin(), old_secret_chat_ids.end(), secret_chat_id),
+                                old_secret_chat_ids.end());
+    }
+    secret_chat->user_id = user_id;
+    secret_chats_with_user_[secret_chat->user_id].push_back(secret_chat_id);
+    secret_chat->need_send_update = true;
+  }
+  if (state != SecretChatState::Unknown && state != secret_chat->state) {
+    secret_chat->state = state;
+    secret_chat->need_send_update = true;
+  }
+  if (is_outbound != secret_chat->is_outbound) {
+    secret_chat->is_outbound = is_outbound;
+    secret_chat->need_send_update = true;
+  }
+
+  if (ttl != -1 && ttl != secret_chat->ttl) {
+    secret_chat->ttl = ttl;
+    secret_chat->need_send_update = true;
+  }
+  if (date != 0 && date != secret_chat->date) {
+    secret_chat->date = date;
+    secret_chat->is_changed = true;
+  }
+  if (!key_hash.empty() && key_hash != secret_chat->key_hash) {
+    secret_chat->key_hash = std::move(key_hash);
+    secret_chat->need_send_update = true;
+  }
+  if (layer != 0 && layer != secret_chat->layer) {
+    secret_chat->layer = layer;
+    secret_chat->need_send_update = true;
+  }
+
+  update_secret_chat(secret_chat, secret_chat_id);
+}
+
+std::pair<int32, vector<UserId>> ContactsManager::search_among_users(const vector<UserId> &user_ids,
+                                                                     const string &query, int32 limit) {
+  Hints hints;  // TODO cache Hints
+
+  UserId my_user_id = get_my_id("search_among_users");
+  for (auto user_id : user_ids) {
+    auto u = get_user(user_id);
+    if (u == nullptr) {
+      continue;
+    }
+    hints.add(user_id.get(), u->first_name + " " + u->last_name + " " + u->username);
+    auto was_online = u->was_online;
+    if (user_id == my_user_id && my_was_online_local_ != 0) {
+      was_online = my_was_online_local_;
+    }
+    hints.set_rating(user_id.get(), -was_online);
+  }
+
+  auto result = hints.search(query, limit, true);
+  return {narrow_cast<int32>(result.first),
+          transform(result.second, [](int64 key) { return UserId(narrow_cast<int32>(key)); })};
+}
+
+DialogParticipant ContactsManager::get_chat_participant(ChatId chat_id, UserId user_id, bool force,
+                                                        Promise<Unit> &&promise) {
+  LOG(INFO) << "Trying to get " << user_id << " as member of " << chat_id;
+  if (force) {
+    promise.set_value(Unit());
+  } else if (!get_chat_full(chat_id, std::move(promise))) {
+    return DialogParticipant();
+  }
+  // promise is already set
+
+  auto result = get_chat_participant(chat_id, user_id);
+  if (result == nullptr) {
+    return {user_id, UserId(), 0, DialogParticipantStatus::Left()};
+  }
+
+  return *result;
+}
+
+std::pair<int32, vector<DialogParticipant>> ContactsManager::search_chat_participants(ChatId chat_id,
+                                                                                      const string &query, int32 limit,
+                                                                                      bool force,
+                                                                                      Promise<Unit> &&promise) {
+  if (limit < 0) {
+    promise.set_error(Status::Error(3, "Parameter limit must be non-negative"));
+    return {};
+  }
+
+  if (force) {
+    promise.set_value(Unit());
+  } else if (!get_chat_full(chat_id, std::move(promise))) {
+    return {};
+  }
+  // promise is already set
+
+  auto chat_full = get_chat_full(chat_id);
+  if (chat_full == nullptr) {
+    return {};
+  }
+
+  auto user_ids = transform(chat_full->participants, [](const auto &participant) { return participant.user_id; });
+  int32 total_count;
+  std::tie(total_count, user_ids) = search_among_users(user_ids, query, limit);
+  return {total_count, transform(user_ids, [&](UserId user_id) { return *get_chat_participant(chat_full, user_id); })};
+}
+
+DialogParticipant ContactsManager::get_channel_participant(ChannelId channel_id, UserId user_id, int64 &random_id,
+                                                           bool force, Promise<Unit> &&promise) {
+  LOG(INFO) << "Trying to get " << user_id << " as member of " << channel_id;
+  if (random_id != 0) {
+    // request has already been sent before
+    auto it = received_channel_participant_.find(random_id);
+    CHECK(it != received_channel_participant_.end());
+    auto result = std::move(it->second);
+    received_channel_participant_.erase(it);
+    promise.set_value(Unit());
+    return result;
+  }
+
+  auto input_user = get_input_user(user_id);
+  if (input_user == nullptr) {
+    promise.set_error(Status::Error(6, "User not found"));
+    return DialogParticipant();
+  }
+
+  if (!td_->auth_manager_->is_bot() && is_user_bot(user_id)) {
+    // get BotInfo through UserFull
+    auto user = get_user(user_id);
+    auto user_full = get_user_full(user_id);
+    if (user_full == nullptr || user_full->is_bot_info_expired(user->bot_info_version)) {
+      if (force) {
+        LOG(ERROR) << "Can't find cached UserFull";
+      } else {
+        send_get_user_full_query(user_id, std::move(input_user), std::move(promise));
+        return DialogParticipant();
+      }
+    }
+  }
+
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 || received_channel_participant_.find(random_id) != received_channel_participant_.end());
+  received_channel_participant_[random_id];  // reserve place for result
+
+  LOG(DEBUG) << "Get info about " << user_id << " membership in the " << channel_id;
+
+  auto on_result_promise = PromiseCreator::lambda(
+      [this, random_id, promise = std::move(promise)](Result<DialogParticipant> r_dialog_participant) mutable {
+        // ResultHandlers are cleared before managers, so it is safe to capture this
+        auto it = received_channel_participant_.find(random_id);
+        CHECK(it != received_channel_participant_.end());
+
+        if (r_dialog_participant.is_error()) {
+          received_channel_participant_.erase(it);
+          promise.set_error(r_dialog_participant.move_as_error());
+        } else {
+          it->second = r_dialog_participant.move_as_ok();
+          promise.set_value(Unit());
+        }
+      });
+
+  td_->create_handler<GetChannelParticipantQuery>(std::move(on_result_promise))
+      ->send(channel_id, user_id, std::move(input_user));
+  return DialogParticipant();
+}
+
+std::pair<int32, vector<DialogParticipant>> ContactsManager::get_channel_participants(
+    ChannelId channel_id, const tl_object_ptr<td_api::SupergroupMembersFilter> &filter, int32 offset, int32 limit,
+    int64 &random_id, bool force, Promise<Unit> &&promise) {
+  if (random_id != 0) {
+    // request has already been sent before
+    auto it = received_channel_participants_.find(random_id);
+    CHECK(it != received_channel_participants_.end());
+    auto result = std::move(it->second);
+    received_channel_participants_.erase(it);
+    promise.set_value(Unit());
+    return result;
+  }
+
+  std::pair<int32, vector<DialogParticipant>> result;
+  if (limit <= 0) {
+    promise.set_error(Status::Error(3, "Parameter limit must be positive"));
+    return result;
+  }
+
+  if (offset < 0) {
+    promise.set_error(Status::Error(3, "Parameter offset must be non-negative"));
+    return result;
+  }
+
+  auto channel_full = get_channel_full(channel_id);
+  if (channel_full == nullptr || (!force && channel_full->is_expired())) {
+    if (force) {
+      LOG(ERROR) << "Can't find cached ChannelFull";
+    } else {
+      auto input_channel = get_input_channel(channel_id);
+      if (input_channel == nullptr) {
+        promise.set_error(Status::Error(6, "Supergroup not found"));
+      } else {
+        send_get_channel_full_query(channel_id, std::move(input_channel), std::move(promise));
+      }
+      return result;
+    }
+  }
+
+  if (channel_full != nullptr && !channel_full->is_expired() && !channel_full->can_get_participants) {
+    promise.set_error(Status::Error(3, "Supergroup members are unavailable"));
+    return result;
+  }
+
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 || received_channel_participants_.find(random_id) != received_channel_participants_.end());
+  received_channel_participants_[random_id];  // reserve place for result
+
+  LOG(DEBUG) << "Get members of the " << channel_id << " with offset = " << offset << " and limit = " << limit;
+
+  td_->create_handler<GetChannelParticipantsQuery>(std::move(promise))
+      ->send(channel_id, ChannelParticipantsFilter(filter), offset, limit, random_id);
+  return result;
+}
+
+vector<UserId> ContactsManager::get_dialog_administrators(DialogId dialog_id, int left_tries, Promise<Unit> &&promise) {
+  auto it = dialog_administrators_.find(dialog_id);
+  if (it != dialog_administrators_.end()) {
+    promise.set_value(Unit());
+    if (left_tries >= 2) {
+      auto hash =
+          get_vector_hash(transform(it->second, [](UserId user_id) { return static_cast<uint32>(user_id.get()); }));
+      reload_dialog_administrators(dialog_id, hash, Auto());  // update administrators cache
+    }
+    return it->second;
+  }
+
+  if (left_tries >= 3) {
+    load_dialog_administrators(dialog_id, std::move(promise));
+    return {};
+  }
+
+  if (left_tries >= 2) {
+    reload_dialog_administrators(dialog_id, 0, std::move(promise));
+    return {};
+  }
+
+  LOG(ERROR) << "Have no known administrators in " << dialog_id;
+  promise.set_value(Unit());
+  return {};
+}
+
+string ContactsManager::get_dialog_administrators_database_key(DialogId dialog_id) {
+  return PSTRING() << "admin" << (-dialog_id.get());
+}
+
+void ContactsManager::load_dialog_administrators(DialogId dialog_id, Promise<Unit> &&promise) {
+  if (G()->parameters().use_chat_info_db) {
+    LOG(INFO) << "Load administrators of " << dialog_id << " from database";
+    G()->td_db()->get_sqlite_pmc()->get(
+        get_dialog_administrators_database_key(dialog_id),
+        PromiseCreator::lambda([dialog_id, promise = std::move(promise)](string value) mutable {
+          send_closure(G()->contacts_manager(), &ContactsManager::on_load_dialog_administrators_from_database,
+                       dialog_id, std::move(value), std::move(promise));
+        }));
+  } else {
+    promise.set_value(Unit());
+  }
+}
+
+void ContactsManager::on_load_dialog_administrators_from_database(DialogId dialog_id, string value,
+                                                                  Promise<Unit> &&promise) {
+  if (value.empty()) {
+    promise.set_value(Unit());
+    return;
+  }
+
+  vector<UserId> user_ids;
+  log_event_parse(user_ids, value).ensure();
+
+  LOG(INFO) << "Successfully loaded " << user_ids.size() << " administrators in " << dialog_id << " from database";
+
+  MultiPromiseActorSafe load_users_multipromise;
+  load_users_multipromise.add_promise(
+      PromiseCreator::lambda([dialog_id, user_ids, promise = std::move(promise)](Result<> result) mutable {
+        send_closure(G()->contacts_manager(), &ContactsManager::on_load_administrator_users_finished, dialog_id,
+                     std::move(user_ids), std::move(result), std::move(promise));
+      }));
+
+  auto lock_promise = load_users_multipromise.get_promise();
+
+  for (auto user_id : user_ids) {
+    get_user(user_id, 3, load_users_multipromise.get_promise());
+  }
+
+  lock_promise.set_value(Unit());
+}
+
+void ContactsManager::on_load_administrator_users_finished(DialogId dialog_id, vector<UserId> user_ids, Result<> result,
+                                                           Promise<Unit> promise) {
+  if (result.is_ok()) {
+    dialog_administrators_.emplace(dialog_id, std::move(user_ids));
+  }
+  promise.set_value(Unit());
+}
+
+void ContactsManager::on_update_dialog_administrators(DialogId dialog_id, vector<UserId> administrator_user_ids,
+                                                      bool have_access) {
+  LOG(INFO) << "Update administrators in " << dialog_id << " to " << format::as_array(administrator_user_ids);
+  if (have_access) {
+    std::sort(administrator_user_ids.begin(), administrator_user_ids.end(),
+              [](UserId lhs, UserId rhs) { return lhs.get() < rhs.get(); });
+
+    auto it = dialog_administrators_.find(dialog_id);
+    if (it != dialog_administrators_.end()) {
+      if (it->second == administrator_user_ids) {
+        return;
+      }
+      it->second = std::move(administrator_user_ids);
+    } else {
+      it = dialog_administrators_.emplace(dialog_id, std::move(administrator_user_ids)).first;
+    }
+
+    if (G()->parameters().use_chat_info_db) {
+      LOG(INFO) << "Save administrators of " << dialog_id << " to database";
+      G()->td_db()->get_sqlite_pmc()->set(get_dialog_administrators_database_key(dialog_id),
+                                          log_event_store(it->second).as_slice().str(), Auto());
+    }
+  } else {
+    if (G()->parameters().use_chat_info_db) {
+      G()->td_db()->get_sqlite_pmc()->erase(get_dialog_administrators_database_key(dialog_id), Auto());
+    }
+  }
+}
+
+void ContactsManager::reload_dialog_administrators(DialogId dialog_id, int32 hash, Promise<Unit> &&promise) {
+  switch (dialog_id.get_type()) {
+    case DialogType::Chat:
+      get_chat_full(dialog_id.get_chat_id(), std::move(promise));
+      break;
+    case DialogType::Channel:
+      td_->create_handler<GetChannelAdministratorsQuery>(std::move(promise))->send(dialog_id.get_channel_id(), hash);
+      break;
+    default:
+      UNREACHABLE();
+  }
+}
+
+void ContactsManager::on_chat_update(telegram_api::chatEmpty &chat) {
+  ChatId chat_id(chat.id_);
+  if (!chat_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << chat_id;
+    return;
+  }
+
+  if (!have_chat(chat_id)) {
+    LOG(ERROR) << "Have no information about " << chat_id << " but received chatEmpty";
+  }
+}
+
+void ContactsManager::on_chat_update(telegram_api::chat &chat) {
+  auto debug_str = oneline(to_string(chat));
+  ChatId chat_id(chat.id_);
+  if (!chat_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << chat_id << " in " << debug_str;
+    return;
+  }
+
+  bool has_left = 0 != (chat.flags_ & CHAT_FLAG_USER_HAS_LEFT);
+  bool was_kicked = 0 != (chat.flags_ & CHAT_FLAG_USER_WAS_KICKED);
+  if (was_kicked) {
+    LOG_IF(ERROR, has_left) << "Kicked and left in " << debug_str;  // only one of the flags can be set
+    has_left = true;
+  }
+
+  bool is_creator = 0 != (chat.flags_ & CHAT_FLAG_USER_IS_CREATOR);
+  bool is_administrator = 0 != (chat.flags_ & CHAT_FLAG_IS_ADMINISTRATOR);
+  bool everyone_is_administrator = 0 == (chat.flags_ & CHAT_FLAG_ADMINISTRATORS_ENABLED);
+
+  bool is_active = 0 == (chat.flags_ & CHAT_FLAG_IS_DEACTIVATED);
+
+  ChannelId migrated_to_channel_id;
+  if (chat.flags_ & CHAT_FLAG_WAS_MIGRATED) {
+    switch (chat.migrated_to_->get_id()) {
+      case telegram_api::inputChannelEmpty::ID: {
+        LOG(ERROR) << "Receive empty upgraded to supergroup for " << chat_id << " in " << debug_str;
+        break;
+      }
+      case telegram_api::inputChannel::ID: {
+        auto input_channel = move_tl_object_as<telegram_api::inputChannel>(chat.migrated_to_);
+        migrated_to_channel_id = ChannelId(input_channel->channel_id_);
+        if (!have_channel(migrated_to_channel_id)) {
+          if (!migrated_to_channel_id.is_valid()) {
+            LOG(ERROR) << "Receive invalid " << migrated_to_channel_id << " in " << debug_str;
+          } else {
+            // temporarily create the channel
+            Channel *c = add_channel(migrated_to_channel_id);
+            c->access_hash = input_channel->access_hash_;
+            c->title = chat.title_;
+            c->status = DialogParticipantStatus::Left();
+            c->is_megagroup = true;
+
+            // we definitely need to call update_channel, because client should know about every added channel
+            update_channel(c, migrated_to_channel_id);
+
+            // get info about the channel
+            td_->create_handler<GetChannelsQuery>(Promise<>())->send(std::move(input_channel));
+          }
+        }
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+  }
+
+  Chat *c = add_chat(chat_id);
+  on_update_chat_title(c, chat_id, std::move(chat.title_));
+  if (!has_left) {
+    on_update_chat_participant_count(c, chat_id, chat.participants_count_, chat.version_, debug_str);
+  }
+  if (c->date != chat.date_) {
+    LOG_IF(ERROR, c->date != 0) << "Chat creation date has changed from " << c->date << " to " << chat.date_ << " in "
+                                << debug_str;
+    c->date = chat.date_;
+    c->is_changed = true;
+  }
+  on_update_chat_left(c, chat_id, has_left, was_kicked);
+  on_update_chat_rights(c, chat_id, is_creator, is_administrator, everyone_is_administrator);
+  on_update_chat_photo(c, chat_id, std::move(chat.photo_));
+  on_update_chat_active(c, chat_id, is_active);
+  on_update_chat_migrated_to_channel_id(c, chat_id, migrated_to_channel_id);
+  LOG_IF(ERROR, !is_active && !migrated_to_channel_id.is_valid()) << chat_id << " is deactivated in " << debug_str;
+  update_chat(c, chat_id);
+}
+
+void ContactsManager::on_chat_update(telegram_api::chatForbidden &chat) {
+  ChatId chat_id(chat.id_);
+  if (!chat_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << chat_id;
+    return;
+  }
+
+  Chat *c = add_chat(chat_id);
+  bool is_uninited = c->left == false && c->kicked == true;
+
+  on_update_chat_title(c, chat_id, std::move(chat.title_));
+  // chat participant count will be updated in on_update_chat_left
+  // leave rights as is
+  on_update_chat_photo(c, chat_id, nullptr);
+  if (c->date != 0) {
+    c->date = 0;  // removed in 38-th layer
+    c->is_changed = true;
+  }
+  on_update_chat_left(c, chat_id, true, true);
+  if (is_uninited) {
+    on_update_chat_active(c, chat_id, true);
+    on_update_chat_migrated_to_channel_id(c, chat_id, ChannelId());
+  } else {
+    // leave active and migrated to as is
+  }
+  update_chat(c, chat_id);
+}
+
+void ContactsManager::on_chat_update(telegram_api::channel &channel) {
+  ChannelId channel_id(channel.id_);
+  if (!channel_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << channel_id << ": " << to_string(channel);
+    return;
+  }
+
+  if (channel.flags_ == 0 && channel.access_hash_ == 0 && channel.title_.empty()) {
+    Channel *c = get_channel_force(channel_id);
+    LOG(ERROR) << "Receive empty " << to_string(channel) << ", have "
+               << to_string(get_supergroup_object(channel_id, c));
+    if (c == nullptr) {
+      min_channels_.insert(channel_id);
+    }
+    return;
+  }
+
+  bool is_min = (channel.flags_ & CHANNEL_FLAG_IS_MIN) != 0;
+  bool has_access_hash = (channel.flags_ & CHANNEL_FLAG_HAS_ACCESS_HASH) != 0;
+  auto access_hash = has_access_hash ? channel.access_hash_ : 0;
+
+  bool anyone_can_invite = (channel.flags_ & CHANNEL_FLAG_ANYONE_CAN_INVITE) != 0;
+  bool sign_messages = (channel.flags_ & CHANNEL_FLAG_SIGN_MESSAGES) != 0;
+  bool is_megagroup = (channel.flags_ & CHANNEL_FLAG_IS_MEGAGROUP) != 0;
+  bool is_verified = (channel.flags_ & CHANNEL_FLAG_IS_VERIFIED) != 0;
+  string restriction_reason = std::move(channel.restriction_reason_);
+  int32 participant_count =
+      (channel.flags_ & CHANNEL_FLAG_HAS_PARTICIPANT_COUNT) != 0 ? channel.participants_count_ : 0;
+
+  {
+    bool is_broadcast = (channel.flags_ & CHANNEL_FLAG_IS_BROADCAST) != 0;
+    LOG_IF(ERROR, is_broadcast == is_megagroup)
+        << "Receive wrong channel flag is_broadcast == is_megagroup == " << is_megagroup << ": "
+        << oneline(to_string(channel));
+  }
+
+  if (!is_megagroup && anyone_can_invite) {
+    LOG(ERROR) << "Anyone can invite new members to the " << channel_id;
+    anyone_can_invite = false;
+  }
+
+  if (is_megagroup) {
+    LOG_IF(ERROR, sign_messages) << "Need to sign messages in the supergroup " << channel_id;
+    sign_messages = true;
+  }
+
+  DialogParticipantStatus status = [&]() {
+    bool has_left = (channel.flags_ & CHANNEL_FLAG_USER_HAS_LEFT) != 0;
+    bool is_creator = (channel.flags_ & CHANNEL_FLAG_USER_IS_CREATOR) != 0;
+
+    if (is_creator) {
+      return DialogParticipantStatus::Creator(!has_left);
+    } else if (channel.admin_rights_ != nullptr) {
+      return get_dialog_participant_status(false, std::move(channel.admin_rights_));
+    } else if (channel.banned_rights_ != nullptr) {
+      return get_dialog_participant_status(!has_left, std::move(channel.banned_rights_));
+    } else if (has_left) {
+      return DialogParticipantStatus::Left();
+    } else {
+      return DialogParticipantStatus::Member();
+    }
+  }();
+
+  if (is_min) {
+    // TODO there can be better support for min channels
+    Channel *c = get_channel_force(channel_id);
+    if (c != nullptr) {
+      LOG(DEBUG) << "Receive known min " << channel_id;
+      on_update_channel_title(c, channel_id, std::move(channel.title_));
+      on_update_channel_username(c, channel_id, std::move(channel.username_));
+      on_update_channel_photo(c, channel_id, std::move(channel.photo_));
+
+      if (c->anyone_can_invite != anyone_can_invite || c->is_megagroup != is_megagroup ||
+          c->is_verified != is_verified) {
+        c->anyone_can_invite = anyone_can_invite;
+        c->is_megagroup = is_megagroup;
+        c->is_verified = is_verified;
+
+        c->need_send_update = true;
+        invalidate_channel_full(channel_id);
+      }
+
+      update_channel(c, channel_id);
+    } else {
+      min_channels_.insert(channel_id);
+    }
+    return;
+  }
+  if (!has_access_hash) {
+    LOG(ERROR) << "Receive non-min " << channel_id << " without access_hash";
+    return;
+  }
+
+  Channel *c = add_channel(channel_id);
+  if (c->status.is_banned()) {  // possibly uninited channel
+    min_channels_.erase(channel_id);
+  }
+  if (c->access_hash != access_hash) {
+    c->access_hash = access_hash;
+    c->is_changed = true;
+  }
+  on_update_channel_title(c, channel_id, std::move(channel.title_));
+  if (c->date != channel.date_) {
+    c->date = channel.date_;
+    c->need_send_update = true;
+  }
+  on_update_channel_photo(c, channel_id, std::move(channel.photo_));
+  on_update_channel_status(c, channel_id, std::move(status));
+  on_update_channel_username(c, channel_id, std::move(channel.username_));  // uses status, must be called after
+
+  if (participant_count != 0 && participant_count != c->participant_count) {
+    c->participant_count = participant_count;
+    c->need_send_update = true;
+  }
+
+  if (c->anyone_can_invite != anyone_can_invite || c->sign_messages != sign_messages ||
+      c->is_megagroup != is_megagroup || c->is_verified != is_verified || c->restriction_reason != restriction_reason) {
+    c->anyone_can_invite = anyone_can_invite;
+    c->sign_messages = sign_messages;
+    c->is_megagroup = is_megagroup;
+    c->is_verified = is_verified;
+    c->restriction_reason = std::move(restriction_reason);
+
+    c->need_send_update = true;
+    invalidate_channel_full(channel_id);
+  }
+
+  update_channel(c, channel_id);
+}
+
+void ContactsManager::on_chat_update(telegram_api::channelForbidden &channel) {
+  ChannelId channel_id(channel.id_);
+  if (!channel_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << channel_id << ": " << to_string(channel);
+    return;
+  }
+
+  if (channel.flags_ == 0 && channel.access_hash_ == 0 && channel.title_.empty()) {
+    Channel *c = get_channel_force(channel_id);
+    LOG(ERROR) << "Receive empty " << to_string(channel) << ", have "
+               << to_string(get_supergroup_object(channel_id, c));
+    if (c == nullptr) {
+      min_channels_.insert(channel_id);
+    }
+    return;
+  }
+
+  Channel *c = add_channel(channel_id);
+  if (c->status.is_banned()) {  // possibly uninited channel
+    min_channels_.erase(channel_id);
+  }
+  if (c->access_hash != channel.access_hash_) {
+    c->access_hash = channel.access_hash_;
+    c->is_changed = true;
+  }
+  on_update_channel_title(c, channel_id, std::move(channel.title_));
+  on_update_channel_photo(c, channel_id, nullptr);
+  if (c->date != 0) {
+    c->date = 0;
+    c->need_send_update = true;
+  }
+  int32 unban_date = (channel.flags_ & CHANNEL_FLAG_HAS_UNBAN_DATE) != 0 ? channel.until_date_ : 0;
+  on_update_channel_status(c, channel_id, DialogParticipantStatus::Banned(unban_date));
+  on_update_channel_username(c, channel_id, "");  // don't know if channel username is empty, but update it anyway
+
+  bool anyone_can_invite = false;
+  bool sign_messages = false;
+  bool is_megagroup = (channel.flags_ & CHANNEL_FLAG_IS_MEGAGROUP) != 0;
+  bool is_verified = false;
+  string restriction_reason;
+
+  {
+    bool is_broadcast = (channel.flags_ & CHANNEL_FLAG_IS_BROADCAST) != 0;
+    LOG_IF(ERROR, is_broadcast == is_megagroup)
+        << "Receive wrong channel flag is_broadcast == is_megagroup == " << is_megagroup << ": "
+        << oneline(to_string(channel));
+  }
+
+  if (is_megagroup) {
+    sign_messages = true;
+  }
+
+  if (c->participant_count != 0) {
+    c->participant_count = 0;
+    c->need_send_update = true;
+  }
+
+  if (c->anyone_can_invite != anyone_can_invite || c->sign_messages != sign_messages ||
+      c->is_megagroup != is_megagroup || c->is_verified != is_verified || c->restriction_reason != restriction_reason) {
+    c->anyone_can_invite = anyone_can_invite;
+    c->sign_messages = sign_messages;
+    c->is_megagroup = is_megagroup;
+    c->is_verified = is_verified;
+    c->restriction_reason = std::move(restriction_reason);
+
+    c->need_send_update = true;
+    invalidate_channel_full(channel_id);
+  }
+
+  update_channel(c, channel_id);
+}
+
+void ContactsManager::on_upload_profile_photo(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) {
+  LOG(INFO) << "File " << file_id << " has been uploaded";
+
+  auto it = uploaded_profile_photos_.find(file_id);
+  CHECK(it != uploaded_profile_photos_.end());
+
+  auto promise = std::move(it->second);
+
+  uploaded_profile_photos_.erase(it);
+
+  FileView file_view = td_->file_manager_->get_file_view(file_id);
+  if (file_view.has_remote_location()) {
+    if (file_view.remote_location().is_web()) {
+      // TODO reupload
+      promise.set_error(Status::Error(400, "Can't use web photo as profile photo"));
+      return;
+    }
+
+    td_->create_handler<UpdateProfilePhotoQuery>(std::move(promise))
+        ->send(file_view.remote_location().as_input_photo());
+    return;
+  }
+  CHECK(input_file != nullptr);
+
+  td_->create_handler<UploadProfilePhotoQuery>(std::move(promise))->send(file_id, std::move(input_file));
+}
+
+void ContactsManager::on_upload_profile_photo_error(FileId file_id, Status status) {
+  LOG(INFO) << "File " << file_id << " has upload error " << status;
+  CHECK(status.is_error());
+
+  auto it = uploaded_profile_photos_.find(file_id);
+  CHECK(it != uploaded_profile_photos_.end());
+
+  auto promise = std::move(it->second);
+
+  uploaded_profile_photos_.erase(it);
+
+  promise.set_error(std::move(status));  // TODO check that status has valid error code
+}
+
+tl_object_ptr<td_api::UserStatus> ContactsManager::get_user_status_object(UserId user_id, const User *u) const {
+  if (u->is_bot) {
+    return make_tl_object<td_api::userStatusOnline>(std::numeric_limits<int32>::max());
+  }
+
+  int32 was_online = u->was_online;
+  if (user_id == get_my_id("get_user_status_object") && my_was_online_local_ != 0) {
+    was_online = my_was_online_local_;
+  }
+  switch (was_online) {
+    case -3:
+      return make_tl_object<td_api::userStatusLastMonth>();
+    case -2:
+      return make_tl_object<td_api::userStatusLastWeek>();
+    case -1:
+      return make_tl_object<td_api::userStatusRecently>();
+    case 0:
+      return make_tl_object<td_api::userStatusEmpty>();
+    default: {
+      int32 time = G()->unix_time();
+      if (was_online > time) {
+        return make_tl_object<td_api::userStatusOnline>(was_online);
+      } else {
+        return make_tl_object<td_api::userStatusOffline>(was_online);
+      }
+    }
+  }
+}
+
+int32 ContactsManager::get_user_id_object(UserId user_id, const char *source) const {
+  if (user_id.is_valid() && get_user(user_id) == nullptr && unknown_users_.count(user_id) == 0) {
+    LOG(ERROR) << "Have no info about " << user_id << " from " << source;
+    unknown_users_.insert(user_id);
+    send_closure(G()->td(), &Td::send_update,
+                 td_api::make_object<td_api::updateUser>(td_api::make_object<td_api::user>(
+                     user_id.get(), "", "", "", "", td_api::make_object<td_api::userStatusEmpty>(),
+                     get_profile_photo_object(td_->file_manager_.get(), nullptr),
+                     get_link_state_object(LinkState::Unknown), get_link_state_object(LinkState::Unknown), false, "",
+                     false, td_api::make_object<td_api::userTypeUnknown>(), "")));
+  }
+  return user_id.get();
+}
+
+tl_object_ptr<td_api::user> ContactsManager::get_user_object(UserId user_id) const {
+  return get_user_object(user_id, get_user(user_id));
+}
+
+tl_object_ptr<td_api::user> ContactsManager::get_user_object(UserId user_id, const User *u) const {
+  if (u == nullptr) {
+    return nullptr;
+  }
+  tl_object_ptr<td_api::UserType> type;
+  if (u->is_deleted) {
+    type = make_tl_object<td_api::userTypeDeleted>();
+  } else if (u->is_bot) {
+    type = make_tl_object<td_api::userTypeBot>(u->can_join_groups, u->can_read_all_group_messages, u->is_inline_bot,
+                                               u->inline_query_placeholder, u->need_location_bot);
+  } else {
+    type = make_tl_object<td_api::userTypeRegular>();
+  }
+
+  return make_tl_object<td_api::user>(
+      user_id.get(), u->first_name, u->last_name, u->username, u->phone_number, get_user_status_object(user_id, u),
+      get_profile_photo_object(td_->file_manager_.get(), &u->photo), get_link_state_object(u->outbound),
+      get_link_state_object(u->inbound), u->is_verified, u->restriction_reason, u->is_received, std::move(type),
+      u->language_code);
+}
+
+vector<int32> ContactsManager::get_user_ids_object(const vector<UserId> &user_ids) const {
+  return transform(user_ids, [this](UserId user_id) { return get_user_id_object(user_id, "get_user_ids_object"); });
+}
+
+tl_object_ptr<td_api::users> ContactsManager::get_users_object(int32 total_count,
+                                                               const vector<UserId> &user_ids) const {
+  if (total_count == -1) {
+    total_count = narrow_cast<int32>(user_ids.size());
+  }
+  return td_api::make_object<td_api::users>(total_count, get_user_ids_object(user_ids));
+}
+
+tl_object_ptr<td_api::userFullInfo> ContactsManager::get_user_full_info_object(UserId user_id) const {
+  return get_user_full_info_object(user_id, get_user_full(user_id));
+}
+
+tl_object_ptr<td_api::userFullInfo> ContactsManager::get_user_full_info_object(UserId user_id,
+                                                                               const UserFull *user_full) const {
+  CHECK(user_full != nullptr);
+  bool is_bot = is_user_bot(user_id);
+  return make_tl_object<td_api::userFullInfo>(user_full->is_blocked, user_full->can_be_called,
+                                              user_full->has_private_calls, is_bot ? string() : user_full->about,
+                                              is_bot ? user_full->about : string(), user_full->common_chat_count,
+                                              get_bot_info_object(user_full->bot_info.get()));
+}
+
+int32 ContactsManager::get_basic_group_id_object(ChatId chat_id, const char *source) const {
+  if (chat_id.is_valid() && get_chat(chat_id) == nullptr && unknown_chats_.count(chat_id) == 0) {
+    LOG(ERROR) << "Have no info about " << chat_id << " from " << source;
+    unknown_chats_.insert(chat_id);
+    send_closure(
+        G()->td(), &Td::send_update,
+        td_api::make_object<td_api::updateBasicGroup>(td_api::make_object<td_api::basicGroup>(
+            chat_id.get(), 0, DialogParticipantStatus::Banned(0).get_chat_member_status_object(), true, true, 0)));
+  }
+  return chat_id.get();
+}
+
+tl_object_ptr<td_api::basicGroup> ContactsManager::get_basic_group_object(ChatId chat_id) {
+  return get_basic_group_object(chat_id, get_chat(chat_id));
+}
+
+tl_object_ptr<td_api::basicGroup> ContactsManager::get_basic_group_object(ChatId chat_id, const Chat *chat) {
+  if (chat == nullptr) {
+    return nullptr;
+  }
+  if (chat->migrated_to_channel_id.is_valid()) {
+    get_channel_force(chat->migrated_to_channel_id);
+  }
+  return make_tl_object<td_api::basicGroup>(
+      chat_id.get(), chat->participant_count, get_chat_status(chat).get_chat_member_status_object(),
+      chat->everyone_is_administrator, chat->is_active,
+      get_supergroup_id_object(chat->migrated_to_channel_id, "get_basic_group_object"));
+}
+
+tl_object_ptr<td_api::basicGroupFullInfo> ContactsManager::get_basic_group_full_info_object(ChatId chat_id) const {
+  return get_basic_group_full_info_object(get_chat_full(chat_id));
+}
+
+tl_object_ptr<td_api::basicGroupFullInfo> ContactsManager::get_basic_group_full_info_object(
+    const ChatFull *chat_full) const {
+  CHECK(chat_full != nullptr);
+  return make_tl_object<td_api::basicGroupFullInfo>(
+      get_user_id_object(chat_full->creator_user_id, "basicGroupFullInfo"),
+      transform(chat_full->participants,
+                [this](const DialogParticipant &chat_participant) { return get_chat_member_object(chat_participant); }),
+      chat_full->invite_link);
+}
+
+int32 ContactsManager::get_supergroup_id_object(ChannelId channel_id, const char *source) const {
+  if (channel_id.is_valid() && get_channel(channel_id) == nullptr && unknown_channels_.count(channel_id) == 0) {
+    LOG(ERROR) << "Have no info about " << channel_id << " received from " << source;
+    unknown_channels_.insert(channel_id);
+    send_closure(G()->td(), &Td::send_update,
+                 td_api::make_object<td_api::updateSupergroup>(td_api::make_object<td_api::supergroup>(
+                     channel_id.get(), string(), 0, DialogParticipantStatus::Banned(0).get_chat_member_status_object(),
+                     0, false, false, true, false, "")));
+  }
+  return channel_id.get();
+}
+
+tl_object_ptr<td_api::supergroup> ContactsManager::get_supergroup_object(ChannelId channel_id) const {
+  return get_supergroup_object(channel_id, get_channel(channel_id));
+}
+
+tl_object_ptr<td_api::supergroup> ContactsManager::get_supergroup_object(ChannelId channel_id,
+                                                                         const Channel *channel) const {
+  if (channel == nullptr) {
+    return nullptr;
+  }
+  return make_tl_object<td_api::supergroup>(
+      channel_id.get(), channel->username, channel->date, get_channel_status(channel).get_chat_member_status_object(),
+      channel->participant_count, channel->anyone_can_invite, channel->sign_messages, !channel->is_megagroup,
+      channel->is_verified, channel->restriction_reason);
+}
+
+tl_object_ptr<td_api::supergroupFullInfo> ContactsManager::get_channel_full_info_object(ChannelId channel_id) const {
+  return get_channel_full_info_object(get_channel_full(channel_id));
+}
+
+tl_object_ptr<td_api::supergroupFullInfo> ContactsManager::get_channel_full_info_object(
+    const ChannelFull *channel_full) const {
+  CHECK(channel_full != nullptr);
+  return make_tl_object<td_api::supergroupFullInfo>(
+      channel_full->description, channel_full->participant_count, channel_full->administrator_count,
+      channel_full->restricted_count, channel_full->banned_count, channel_full->can_get_participants,
+      channel_full->can_set_username, channel_full->can_set_sticker_set, channel_full->is_all_history_available,
+      channel_full->sticker_set_id, channel_full->invite_link, channel_full->pinned_message_id.get(),
+      get_basic_group_id_object(channel_full->migrated_from_chat_id, "get_channel_full_info_object"),
+      channel_full->migrated_from_max_message_id.get());
+}
+
+tl_object_ptr<td_api::SecretChatState> ContactsManager::get_secret_chat_state_object(SecretChatState state) {
+  switch (state) {
+    case SecretChatState::Waiting:
+      return make_tl_object<td_api::secretChatStatePending>();
+    case SecretChatState::Active:
+      return make_tl_object<td_api::secretChatStateReady>();
+    case SecretChatState::Closed:
+    case SecretChatState::Unknown:
+      return make_tl_object<td_api::secretChatStateClosed>();
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+int32 ContactsManager::get_secret_chat_id_object(SecretChatId secret_chat_id, const char *source) const {
+  if (secret_chat_id.is_valid() && get_secret_chat(secret_chat_id) == nullptr &&
+      unknown_secret_chats_.count(secret_chat_id) == 0) {
+    LOG(ERROR) << "Have no info about " << secret_chat_id << " from " << source;
+    unknown_secret_chats_.insert(secret_chat_id);
+    send_closure(
+        G()->td(), &Td::send_update,
+        td_api::make_object<td_api::updateSecretChat>(td_api::make_object<td_api::secretChat>(
+            secret_chat_id.get(), 0, get_secret_chat_state_object(SecretChatState::Unknown), false, 0, string(), 0)));
+  }
+  return secret_chat_id.get();
+}
+
+tl_object_ptr<td_api::secretChat> ContactsManager::get_secret_chat_object(SecretChatId secret_chat_id) {
+  return get_secret_chat_object(secret_chat_id, get_secret_chat(secret_chat_id));
+}
+
+tl_object_ptr<td_api::secretChat> ContactsManager::get_secret_chat_object(SecretChatId secret_chat_id,
+                                                                          const SecretChat *secret_chat) {
+  if (secret_chat == nullptr) {
+    return nullptr;
+  }
+  get_user_force(secret_chat->user_id);
+  return td_api::make_object<td_api::secretChat>(
+      secret_chat_id.get(), get_user_id_object(secret_chat->user_id, "secretChat"),
+      get_secret_chat_state_object(secret_chat->state), secret_chat->is_outbound, secret_chat->ttl,
+      secret_chat->key_hash, secret_chat->layer);
+}
+
+tl_object_ptr<td_api::LinkState> ContactsManager::get_link_state_object(LinkState link) {
+  switch (link) {
+    case LinkState::Unknown:
+    case LinkState::None:
+      return make_tl_object<td_api::linkStateNone>();
+    case LinkState::KnowsPhoneNumber:
+      return make_tl_object<td_api::linkStateKnowsPhoneNumber>();
+    case LinkState::Contact:
+      return make_tl_object<td_api::linkStateIsContact>();
+    default:
+      UNREACHABLE();
+  }
+  return make_tl_object<td_api::linkStateNone>();
+}
+
+tl_object_ptr<td_api::botInfo> ContactsManager::get_bot_info_object(const BotInfo *bot_info) {
+  if (bot_info == nullptr) {
+    return nullptr;
+  }
+
+  vector<tl_object_ptr<td_api::botCommand>> commands;
+  for (auto &command : bot_info->commands) {
+    commands.push_back(make_tl_object<td_api::botCommand>(command.first, command.second));
+  }
+
+  return make_tl_object<td_api::botInfo>(bot_info->description, std::move(commands));
+}
+
+tl_object_ptr<td_api::botInfo> ContactsManager::get_bot_info_object(UserId user_id) const {
+  auto user_full = get_user_full(user_id);
+  if (user_full == nullptr || user_full->bot_info == nullptr) {
+    return nullptr;
+  }
+  return get_bot_info_object(user_full->bot_info.get());
+}
+
+tl_object_ptr<td_api::chatInviteLinkInfo> ContactsManager::get_chat_invite_link_info_object(
+    const string &invite_link) const {
+  auto it = invite_link_infos_.find(invite_link);
+  if (it == invite_link_infos_.end()) {
+    return nullptr;
+  }
+
+  auto invite_link_info = it->second.get();
+  CHECK(invite_link_info != nullptr);
+
+  DialogId dialog_id;
+  string title;
+  const DialogPhoto *photo = nullptr;
+  int32 participant_count = 0;
+  vector<int32> member_user_ids;
+  bool is_public = false;
+  td_api::object_ptr<td_api::ChatType> chat_type;
+
+  if (invite_link_info->chat_id != ChatId()) {
+    CHECK(invite_link_info->channel_id == ChannelId());
+    auto chat_id = invite_link_info->chat_id;
+    const Chat *c = get_chat(chat_id);
+
+    dialog_id = DialogId(invite_link_info->chat_id);
+
+    if (c != nullptr) {
+      title = c->title;
+      photo = &c->photo;
+      participant_count = c->participant_count;
+    } else {
+      LOG(ERROR) << "Have no information about " << chat_id;
+    }
+    chat_type = td_api::make_object<td_api::chatTypeBasicGroup>(
+        get_basic_group_id_object(chat_id, "get_chat_invite_link_info_object"));
+  } else if (invite_link_info->channel_id != ChannelId()) {
+    CHECK(invite_link_info->chat_id == ChatId());
+    auto channel_id = invite_link_info->channel_id;
+    const Channel *c = get_channel(channel_id);
+
+    dialog_id = DialogId(invite_link_info->channel_id);
+
+    bool is_megagroup = false;
+    if (c != nullptr) {
+      title = c->title;
+      photo = &c->photo;
+      is_public = !c->username.empty();
+      is_megagroup = c->is_megagroup;
+      participant_count = c->participant_count;
+    } else {
+      LOG(ERROR) << "Have no information about " << channel_id;
+    }
+    chat_type = td_api::make_object<td_api::chatTypeSupergroup>(
+        get_supergroup_id_object(channel_id, "get_chat_invite_link_info_object"), !is_megagroup);
+  } else {
+    title = invite_link_info->title;
+    photo = &invite_link_info->photo;
+    participant_count = invite_link_info->participant_count;
+    member_user_ids = get_user_ids_object(invite_link_info->participant_user_ids);
+    is_public = invite_link_info->is_public;
+
+    if (invite_link_info->is_chat) {
+      chat_type = td_api::make_object<td_api::chatTypeBasicGroup>(0);
+    } else {
+      chat_type = td_api::make_object<td_api::chatTypeSupergroup>(0, !invite_link_info->is_megagroup);
+    }
+  }
+
+  if (dialog_id != DialogId()) {
+    td_->messages_manager_->force_create_dialog(dialog_id, "get_chat_invite_link_info_object");
+  }
+
+  return make_tl_object<td_api::chatInviteLinkInfo>(dialog_id.get(), std::move(chat_type), title,
+                                                    get_chat_photo_object(td_->file_manager_.get(), photo),
+                                                    participant_count, std::move(member_user_ids), is_public);
+}
+
+UserId ContactsManager::get_support_user(Promise<Unit> &&promise) {
+  if (support_user_id_.is_valid()) {
+    promise.set_value(Unit());
+    return support_user_id_;
+  }
+
+  td_->create_handler<GetSupportUserQuery>(std::move(promise))->send();
+  return UserId();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/ContactsManager.h b/libs/tdlib/td/td/telegram/ContactsManager.h
new file mode 100644
index 0000000000..fc1bfc34ff
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/ContactsManager.h
@@ -0,0 +1,1091 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/MultiPromise.h"
+#include "td/actor/PromiseFuture.h"
+#include "td/actor/Timeout.h"
+
+#include "td/db/binlog/BinlogEvent.h"
+
+#include "td/telegram/AccessRights.h"
+#include "td/telegram/ChannelId.h"
+#include "td/telegram/ChatId.h"
+#include "td/telegram/Contact.h"
+#include "td/telegram/DialogId.h"
+#include "td/telegram/DialogParticipant.h"
+#include "td/telegram/files/FileId.h"
+#include "td/telegram/MessageId.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/SecretChatId.h"
+#include "td/telegram/UserId.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Hints.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+
+#include <memory>
+#include <unordered_map>
+#include <unordered_set>
+#include <utility>
+
+namespace td {
+
+class Td;
+
+struct BotData {
+  string username;
+  bool can_join_groups;
+  bool can_read_all_group_messages;
+  bool is_inline;
+  bool need_location;
+};
+
+enum class ChannelType { Broadcast, Megagroup, Unknown };
+
+enum class CheckDialogUsernameResult { Ok, Invalid, Occupied, PublicDialogsTooMuch, PublicGroupsUnavailable };
+
+class ContactsManager : public Actor {
+ public:
+  ContactsManager(Td *td, ActorShared<> parent);
+
+  static UserId load_my_id();
+
+  static UserId get_user_id(const tl_object_ptr<telegram_api::User> &user);
+  static ChatId get_chat_id(const tl_object_ptr<telegram_api::Chat> &chat);
+  static ChannelId get_channel_id(const tl_object_ptr<telegram_api::Chat> &chat);
+
+  tl_object_ptr<telegram_api::InputUser> get_input_user(UserId user_id) const;
+  bool have_input_user(UserId user_id) const;
+
+  // TODO get_input_chat ???
+
+  tl_object_ptr<telegram_api::InputChannel> get_input_channel(ChannelId channel_id) const;
+
+  tl_object_ptr<telegram_api::InputPeer> get_input_peer_user(UserId user_id, AccessRights access_rights) const;
+  bool have_input_peer_user(UserId user_id, AccessRights access_rights) const;
+
+  tl_object_ptr<telegram_api::InputPeer> get_input_peer_chat(ChatId chat_id, AccessRights access_rights) const;
+  bool have_input_peer_chat(ChatId chat_id, AccessRights access_rights) const;
+
+  tl_object_ptr<telegram_api::InputPeer> get_input_peer_channel(ChannelId channel_id, AccessRights access_rights) const;
+  bool have_input_peer_channel(ChannelId channel_id, AccessRights access_rights) const;
+
+  tl_object_ptr<telegram_api::inputEncryptedChat> get_input_encrypted_chat(SecretChatId secret_chat_id,
+                                                                           AccessRights access_rights) const;
+  bool have_input_encrypted_peer(SecretChatId secret_chat_id, AccessRights access_rights) const;
+
+  const DialogPhoto *get_user_dialog_photo(UserId user_id) const;
+  const DialogPhoto *get_chat_dialog_photo(ChatId chat_id) const;
+  const DialogPhoto *get_channel_dialog_photo(ChannelId channel_id) const;
+  const DialogPhoto *get_secret_chat_dialog_photo(SecretChatId secret_chat_id) const;
+
+  string get_user_title(UserId user_id) const;
+  string get_chat_title(ChatId chat_id) const;
+  string get_channel_title(ChannelId channel_id) const;
+  string get_secret_chat_title(SecretChatId secret_chat_id) const;
+
+  bool is_update_about_username_change_received(UserId user_id) const;
+
+  string get_user_username(UserId user_id) const;
+  string get_channel_username(ChannelId channel_id) const;
+  string get_secret_chat_username(SecretChatId secret_chat_id) const;
+
+  int32 get_secret_chat_date(SecretChatId secret_chat_id) const;
+  int32 get_secret_chat_ttl(SecretChatId secret_chat_id) const;
+  UserId get_secret_chat_user_id(SecretChatId secret_chat_id) const;
+  SecretChatState get_secret_chat_state(SecretChatId secret_chat_id) const;
+  int32 get_secret_chat_layer(SecretChatId secret_chat_id) const;
+
+  bool default_can_report_spam_in_secret_chat(SecretChatId secret_chat_id) const;
+
+  void on_imported_contacts(int64 random_id, vector<UserId> imported_contact_user_ids,
+                            vector<int32> unimported_contact_invites);
+
+  void on_deleted_contacts(const vector<UserId> &deleted_contact_user_ids);
+
+  void on_get_contacts(tl_object_ptr<telegram_api::contacts_Contacts> &&new_contacts);
+
+  void on_get_contacts_failed(Status error);
+
+  void on_get_contacts_statuses(vector<tl_object_ptr<telegram_api::contactStatus>> &&statuses);
+
+  void reload_contacts(bool force);
+
+  void on_get_contacts_link(tl_object_ptr<telegram_api::contacts_link> &&link);
+
+  void on_get_user(tl_object_ptr<telegram_api::User> &&user, bool is_me = false, bool is_support = false);
+  void on_get_users(vector<tl_object_ptr<telegram_api::User>> &&users);
+
+  void on_binlog_user_event(BinlogEvent &&event);
+  void on_binlog_chat_event(BinlogEvent &&event);
+  void on_binlog_channel_event(BinlogEvent &&event);
+  void on_binlog_secret_chat_event(BinlogEvent &&event);
+
+  void on_get_user_full(tl_object_ptr<telegram_api::userFull> &&user_full);
+
+  void on_get_user_photos(UserId user_id, int32 offset, int32 limit, int32 total_count,
+                          vector<tl_object_ptr<telegram_api::Photo>> photos);
+
+  void on_get_chat(tl_object_ptr<telegram_api::Chat> &&chat);
+  void on_get_chats(vector<tl_object_ptr<telegram_api::Chat>> &&chats);
+
+  void on_get_chat_full(tl_object_ptr<telegram_api::ChatFull> &&chat_full);
+
+  void on_update_profile_success(int32 flags, const string &first_name, const string &last_name, const string &about);
+
+  void on_update_user_name(UserId user_id, string &&first_name, string &&last_name, string &&username);
+  void on_update_user_phone_number(UserId user_id, string &&phone_number);
+  void on_update_user_photo(UserId user_id, tl_object_ptr<telegram_api::UserProfilePhoto> &&photo_ptr);
+  void on_update_user_online(UserId user_id, tl_object_ptr<telegram_api::UserStatus> &&status);
+  void on_update_user_links(UserId user_id, tl_object_ptr<telegram_api::ContactLink> &&outbound,
+                            tl_object_ptr<telegram_api::ContactLink> &&inbound);
+  void on_update_user_blocked(UserId user_id, bool is_blocked);
+
+  void on_delete_profile_photo(int64 profile_photo_id, Promise<Unit> promise);
+
+  void on_get_chat_participants(tl_object_ptr<telegram_api::ChatParticipants> &&participants);
+  void on_update_chat_add_user(ChatId chat_id, UserId inviter_user_id, UserId user_id, int32 date, int32 version);
+  void on_update_chat_edit_administrator(ChatId chat_id, UserId user_id, bool is_administrator, int32 version);
+  void on_update_chat_delete_user(ChatId chat_id, UserId user_id, int32 version);
+  void on_update_chat_everyone_is_administrator(ChatId chat_id, bool everyone_is_administrator, int32 version);
+
+  void on_update_channel_username(ChannelId channel_id, string &&username);
+  void on_update_channel_description(ChannelId channel_id, string &&description);
+  void on_update_channel_sticker_set(ChannelId channel_id, int64 sticker_set_id);
+  void on_update_channel_pinned_message(ChannelId channel_id, MessageId message_id);
+  void on_update_channel_is_all_history_available(ChannelId channel_id, bool is_all_history_available);
+
+  void on_update_dialog_administrators(DialogId dialog_id, vector<UserId> administrator_user_ids, bool have_access);
+
+  static bool speculative_add_count(int32 &count, int32 new_count);
+
+  void speculative_add_channel_participants(ChannelId channel_id, int32 new_participant_count, bool by_me);
+
+  void invalidate_channel_full(ChannelId channel_id);
+
+  bool on_get_channel_error(ChannelId channel_id, const Status &status, const string &source);
+
+  void on_get_channel_participants_success(ChannelId channel_id, ChannelParticipantsFilter filter, int32 offset,
+                                           int32 limit, int64 random_id, int32 total_count,
+                                           vector<tl_object_ptr<telegram_api::ChannelParticipant>> &&participants);
+
+  void on_get_channel_participants_fail(ChannelId channel_id, ChannelParticipantsFilter filter, int32 offset,
+                                        int32 limit, int64 random_id);
+
+  static Slice get_dialog_invite_link_hash(const string &invite_link);
+
+  void on_get_chat_invite_link(ChatId chat_id, tl_object_ptr<telegram_api::ExportedChatInvite> &&invite_link_ptr);
+
+  void on_get_channel_invite_link(ChannelId channel_id,
+                                  tl_object_ptr<telegram_api::ExportedChatInvite> &&invite_link_ptr);
+
+  void on_get_dialog_invite_link_info(const string &invite_link,
+                                      tl_object_ptr<telegram_api::ChatInvite> &&chat_invite_ptr);
+
+  void invalidate_invite_link(const string &invite_link);
+
+  void on_get_created_public_channels(vector<tl_object_ptr<telegram_api::Chat>> &&chats);
+
+  void on_get_user_full_success(UserId user_id);
+
+  void on_get_user_full_fail(UserId user_id, Status &&error);
+
+  void on_get_chat_full_success(ChatId chat_id);
+
+  void on_get_chat_full_fail(ChatId chat_id, Status &&error);
+
+  void on_get_channel_full_success(ChannelId channel_id);
+
+  void on_get_channel_full_fail(ChannelId channel_id, Status &&error);
+
+  UserId get_my_id(const char *source) const;
+  void set_my_online_status(bool is_online, bool send_update, bool is_local);
+
+  void on_update_online_status_privacy();
+
+  void on_channel_unban_timeout(ChannelId channel_id);
+
+  void check_dialog_username(DialogId dialog_id, const string &username, Promise<CheckDialogUsernameResult> &&promise);
+
+  static td_api::object_ptr<td_api::CheckChatUsernameResult> get_check_chat_username_result_object(
+      CheckDialogUsernameResult result);
+
+  void set_account_ttl(int32 account_ttl, Promise<Unit> &&promise) const;
+  void get_account_ttl(Promise<int32> &&promise) const;
+
+  void get_active_sessions(Promise<tl_object_ptr<td_api::sessions>> &&promise) const;
+  void terminate_session(int64 session_id, Promise<Unit> &&promise) const;
+  void terminate_all_other_sessions(Promise<Unit> &&promise) const;
+
+  void get_connected_websites(Promise<tl_object_ptr<td_api::connectedWebsites>> &&promise) const;
+  void disconnect_website(int64 authorizations_id, Promise<Unit> &&promise) const;
+  void disconnect_all_websites(Promise<Unit> &&promise) const;
+
+  Status block_user(UserId user_id);
+
+  Status unblock_user(UserId user_id);
+
+  int64 get_blocked_users(int32 offset, int32 limit, Promise<Unit> &&promise);
+
+  void on_get_blocked_users_result(int32 offset, int32 limit, int64 random_id, int32 total_count,
+                                   vector<tl_object_ptr<telegram_api::contactBlocked>> &&blocked_users);
+
+  void on_failed_get_blocked_users(int64 random_id);
+
+  tl_object_ptr<td_api::users> get_blocked_users_object(int64 random_id);
+
+  std::pair<vector<UserId>, vector<int32>> import_contacts(const vector<tl_object_ptr<td_api::contact>> &contacts,
+                                                           int64 &random_id, Promise<Unit> &&promise);
+
+  std::pair<int32, vector<UserId>> search_contacts(const string &query, int32 limit, Promise<Unit> &&promise);
+
+  void remove_contacts(vector<UserId> user_ids, Promise<Unit> &&promise);
+
+  int32 get_imported_contact_count(Promise<Unit> &&promise);
+
+  std::pair<vector<UserId>, vector<int32>> change_imported_contacts(vector<tl_object_ptr<td_api::contact>> &&contacts,
+                                                                    int64 &random_id, Promise<Unit> &&promise);
+
+  void clear_imported_contacts(Promise<Unit> &&promise);
+
+  void on_update_contacts_reset();
+
+  void set_profile_photo(const tl_object_ptr<td_api::InputFile> &input_photo, Promise<Unit> &&promise);
+
+  void delete_profile_photo(int64 profile_photo_id, Promise<Unit> &&promise);
+
+  void set_name(const string &first_name, const string &last_name, Promise<Unit> &&promise);
+
+  void set_bio(const string &bio, Promise<Unit> &&promise);
+
+  void set_username(const string &username, Promise<Unit> &&promise);
+
+  void toggle_chat_administrators(ChatId chat_id, bool everyone_is_administrator, Promise<Unit> &&promise);
+
+  void set_channel_username(ChannelId channel_id, const string &username, Promise<Unit> &&promise);
+
+  void set_channel_sticker_set(ChannelId channel_id, int64 sticker_set_id, Promise<Unit> &&promise);
+
+  void toggle_channel_invites(ChannelId channel_id, bool anyone_can_invite, Promise<Unit> &&promise);
+
+  void toggle_channel_sign_messages(ChannelId channel_id, bool sign_messages, Promise<Unit> &&promise);
+
+  void toggle_channel_is_all_history_available(ChannelId channel_id, bool is_all_history_available,
+                                               Promise<Unit> &&promise);
+
+  void set_channel_description(ChannelId channel_id, const string &description, Promise<Unit> &&promise);
+
+  void pin_channel_message(ChannelId channel_id, MessageId message_id, bool disable_notification,
+                           Promise<Unit> &&promise);
+
+  void unpin_channel_message(ChannelId channel_id, Promise<Unit> &&promise);
+
+  void report_channel_spam(ChannelId channel_id, UserId user_id, const vector<MessageId> &message_ids,
+                           Promise<Unit> &&promise);
+
+  void delete_channel(ChannelId channel_id, Promise<Unit> &&promise);
+
+  void add_chat_participant(ChatId chat_id, UserId user_id, int32 forward_limit, Promise<Unit> &&promise);
+
+  void add_channel_participant(ChannelId channel_id, UserId user_id, Promise<Unit> &&promise,
+                               DialogParticipantStatus old_status = DialogParticipantStatus::Left());
+
+  void add_channel_participants(ChannelId channel_id, const vector<UserId> &user_ids, Promise<Unit> &&promise);
+
+  void change_chat_participant_status(ChatId chat_id, UserId user_id, DialogParticipantStatus status,
+                                      Promise<Unit> &&promise);
+
+  void change_channel_participant_status(ChannelId channel_id, UserId user_id, DialogParticipantStatus status,
+                                         Promise<Unit> &&promise);
+
+  void export_chat_invite_link(ChatId chat_id, Promise<Unit> &&promise);
+
+  void export_channel_invite_link(ChannelId channel_id, Promise<Unit> &&promise);
+
+  void check_dialog_invite_link(const string &invite_link, Promise<Unit> &&promise) const;
+
+  void import_dialog_invite_link(const string &invite_link, Promise<DialogId> &&promise);
+
+  string get_chat_invite_link(ChatId chat_id) const;
+
+  string get_channel_invite_link(ChannelId channel_id);
+
+  MessageId get_channel_pinned_message_id(ChannelId channel_id);
+
+  ChannelId migrate_chat_to_megagroup(ChatId chat_id, Promise<Unit> &promise);
+
+  vector<DialogId> get_created_public_dialogs(Promise<Unit> &&promise);
+
+  bool is_user_deleted(UserId user_id) const;
+
+  bool is_user_bot(UserId user_id) const;
+  Result<BotData> get_bot_data(UserId user_id) const TD_WARN_UNUSED_RESULT;
+
+  bool have_user(UserId user_id) const;
+  bool have_min_user(UserId user_id) const;
+  bool have_user_force(UserId user_id);
+
+  static void send_get_me_query(Td *td, Promise<Unit> &&promise);
+  UserId get_me(Promise<Unit> &&promise);
+  bool get_user(UserId user_id, int left_tries, Promise<Unit> &&promise);
+  bool get_user_full(UserId user_id, Promise<Unit> &&promise);
+
+  std::pair<int32, vector<const Photo *>> get_user_profile_photos(UserId user_id, int32 offset, int32 limit,
+                                                                  Promise<Unit> &&promise);
+
+  bool have_chat(ChatId chat_id) const;
+  bool have_chat_force(ChatId chat_id);
+  bool get_chat(ChatId chat_id, int left_tries, Promise<Unit> &&promise);
+  bool get_chat_full(ChatId chat_id, Promise<Unit> &&promise);
+
+  bool get_chat_is_active(ChatId chat_id) const;
+  DialogParticipantStatus get_chat_status(ChatId chat_id) const;
+  bool is_appointed_chat_administrator(ChatId chat_id) const;
+
+  bool have_channel(ChannelId channel_id) const;
+  bool have_min_channel(ChannelId channel_id) const;
+  bool have_channel_force(ChannelId channel_id);
+  bool get_channel(ChannelId channel_id, int left_tries, Promise<Unit> &&promise);
+  bool get_channel_full(ChannelId channel_id, Promise<Unit> &&promise);
+
+  bool have_secret_chat(SecretChatId secret_chat_id) const;
+  bool have_secret_chat_force(SecretChatId secret_chat_id);
+  bool get_secret_chat(SecretChatId secret_chat_id, bool force, Promise<Unit> &&promise);
+  bool get_secret_chat_full(SecretChatId secret_chat_id, Promise<Unit> &&promise);
+
+  ChannelType get_channel_type(ChannelId channel_id) const;
+  int32 get_channel_date(ChannelId channel_id) const;
+  DialogParticipantStatus get_channel_status(ChannelId channel_id) const;
+  bool get_channel_sign_messages(ChannelId channel_id) const;
+
+  std::pair<int32, vector<UserId>> search_among_users(const vector<UserId> &user_ids, const string &query, int32 limit);
+
+  DialogParticipant get_chat_participant(ChatId chat_id, UserId user_id, bool force, Promise<Unit> &&promise);
+
+  std::pair<int32, vector<DialogParticipant>> search_chat_participants(ChatId chat_id, const string &query, int32 limit,
+                                                                       bool force, Promise<Unit> &&promise);
+
+  DialogParticipant get_channel_participant(ChannelId channel_id, UserId user_id, int64 &random_id, bool force,
+                                            Promise<Unit> &&promise);
+
+  std::pair<int32, vector<DialogParticipant>> get_channel_participants(
+      ChannelId channel_id, const tl_object_ptr<td_api::SupergroupMembersFilter> &filter, int32 offset, int32 limit,
+      int64 &random_id, bool force, Promise<Unit> &&promise);
+
+  DialogParticipant get_dialog_participant(ChannelId channel_id,
+                                           tl_object_ptr<telegram_api::ChannelParticipant> &&participant_ptr) const;
+
+  vector<UserId> get_dialog_administrators(DialogId chat_id, int left_tries, Promise<Unit> &&promise);
+
+  int32 get_user_id_object(UserId user_id, const char *source) const;
+
+  tl_object_ptr<td_api::user> get_user_object(UserId user_id) const;
+
+  vector<int32> get_user_ids_object(const vector<UserId> &user_ids) const;
+
+  tl_object_ptr<td_api::users> get_users_object(int32 total_count, const vector<UserId> &user_ids) const;
+
+  tl_object_ptr<td_api::userFullInfo> get_user_full_info_object(UserId user_id) const;
+
+  int32 get_basic_group_id_object(ChatId chat_id, const char *source) const;
+
+  tl_object_ptr<td_api::basicGroup> get_basic_group_object(ChatId chat_id);
+
+  tl_object_ptr<td_api::basicGroupFullInfo> get_basic_group_full_info_object(ChatId chat_id) const;
+
+  int32 get_supergroup_id_object(ChannelId channel_id, const char *source) const;
+
+  tl_object_ptr<td_api::supergroup> get_supergroup_object(ChannelId channel_id) const;
+
+  tl_object_ptr<td_api::supergroupFullInfo> get_channel_full_info_object(ChannelId channel_id) const;
+
+  int32 get_secret_chat_id_object(SecretChatId secret_chat_id, const char *source) const;
+
+  tl_object_ptr<td_api::secretChat> get_secret_chat_object(SecretChatId secret_chat_id);
+
+  void on_update_secret_chat(SecretChatId secret_chat_id, int64 access_hash, UserId user_id, SecretChatState state,
+                             bool is_outbound, int32 ttl, int32 date, string key_hash, int32 layer);
+
+  void on_upload_profile_photo(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file);
+  void on_upload_profile_photo_error(FileId file_id, Status status);
+
+  tl_object_ptr<td_api::chatMember> get_chat_member_object(const DialogParticipant &dialog_participant) const;
+
+  tl_object_ptr<td_api::botInfo> get_bot_info_object(UserId user_id) const;
+
+  tl_object_ptr<td_api::chatInviteLinkInfo> get_chat_invite_link_info_object(const string &invite_link) const;
+
+  UserId get_support_user(Promise<Unit> &&promise);
+
+ private:
+  enum class LinkState : uint8 { Unknown, None, KnowsPhoneNumber, Contact };
+
+  friend StringBuilder &operator<<(StringBuilder &string_builder, LinkState link_state);
+
+  struct User {
+    string first_name;
+    string last_name;
+    string username;
+    string phone_number;
+    int64 access_hash = -1;
+
+    ProfilePhoto photo;
+
+    string restriction_reason;
+    string inline_query_placeholder;
+    int32 bot_info_version = -1;
+
+    int32 was_online = 0;
+
+    string language_code;
+
+    LinkState outbound = LinkState::Unknown;
+    LinkState inbound = LinkState::Unknown;
+
+    bool is_received = false;
+    bool is_verified = false;
+    bool is_deleted = true;
+    bool is_bot = true;
+    bool can_join_groups = true;
+    bool can_read_all_group_messages = true;
+    bool is_inline_bot = false;
+    bool need_location_bot = false;
+
+    bool is_name_changed = true;
+    bool is_username_changed = true;
+    bool is_photo_changed = true;
+    bool is_outbound_link_changed = true;
+    bool is_changed = true;        // have new changes not sent to the database except changes visible to the client
+    bool need_send_update = true;  // have new changes not sent to the client
+    bool is_status_changed = true;
+
+    bool is_saved = false;         // is current user version being saved/is saved to the database
+    bool is_being_saved = false;   // is current user being saved to the database
+    bool is_status_saved = false;  // is current user status being saved/is saved to the database
+
+    uint64 logevent_id = 0;
+
+    template <class StorerT>
+    void store(StorerT &storer) const;
+
+    template <class ParserT>
+    void parse(ParserT &parser);
+  };
+
+  struct BotInfo {
+    int32 version = -1;
+    string description;
+    vector<std::pair<string, string>> commands;
+
+    BotInfo(int32 version, string description, vector<std::pair<string, string>> &&commands)
+        : version(version), description(std::move(description)), commands(std::move(commands)) {
+    }
+  };
+
+  // do not forget to update invalidate_user_full and on_get_user_full
+  struct UserFull {
+    vector<Photo> photos;
+    int32 photo_count = -1;
+    int32 photos_offset = -1;
+
+    std::unique_ptr<BotInfo> bot_info;
+
+    string about;
+
+    int32 common_chat_count = 0;
+
+    bool getting_photos_now = false;
+
+    bool is_inited = false;  // photos and bot_info may be inited regardless this flag
+    bool is_blocked = false;
+    bool can_be_called = false;
+    bool has_private_calls = false;
+
+    bool is_changed = true;
+
+    double expires_at = 0.0;
+
+    bool is_bot_info_expired(int32 bot_info_version) const;
+    bool is_expired() const;
+  };
+
+  struct Chat {
+    string title;
+    DialogPhoto photo;
+    int32 participant_count = 0;
+    int32 date = 0;
+    int32 version = -1;
+    ChannelId migrated_to_channel_id;
+
+    bool left = false;
+    bool kicked = true;
+
+    bool is_creator = false;
+    bool is_administrator = false;
+    bool everyone_is_administrator = true;
+    bool can_edit = true;
+
+    bool is_active = false;
+
+    bool is_title_changed = true;
+    bool is_photo_changed = true;
+    bool is_changed = true;        // have new changes not sent to the database except changes visible to the client
+    bool need_send_update = true;  // have new changes not sent to the client
+
+    bool is_saved = false;        // is current chat version being saved/is saved to the database
+    bool is_being_saved = false;  // is current chat being saved to the database
+    uint64 logevent_id = 0;
+
+    template <class StorerT>
+    void store(StorerT &storer) const;
+
+    template <class ParserT>
+    void parse(ParserT &parser);
+  };
+
+  struct ChatFull {
+    int32 version = -1;
+    UserId creator_user_id;
+    vector<DialogParticipant> participants;
+
+    string invite_link;
+
+    bool is_changed = true;
+  };
+
+  struct Channel {
+    int64 access_hash = 0;
+    string title;
+    DialogPhoto photo;
+    string username;
+    string restriction_reason;
+    DialogParticipantStatus status = DialogParticipantStatus::Banned(0);
+    int32 date = 0;
+    int32 participant_count = 0;
+
+    bool anyone_can_invite = false;
+    bool sign_messages = false;
+
+    bool is_megagroup = false;
+    bool is_verified = false;
+
+    bool is_title_changed = true;
+    bool is_username_changed = true;
+    bool is_photo_changed = true;
+    bool is_status_changed = true;
+    bool had_read_access = true;
+    bool was_member = false;
+    bool is_changed = true;        // have new changes not sent to the database except changes visible to the client
+    bool need_send_update = true;  // have new changes not sent to the client
+
+    bool is_saved = false;        // is current channel version being saved/is saved to the database
+    bool is_being_saved = false;  // is current channel being saved to the database
+    uint64 logevent_id = 0;
+
+    template <class StorerT>
+    void store(StorerT &storer) const;
+
+    template <class ParserT>
+    void parse(ParserT &parser);
+  };
+
+  struct ChannelFull {
+    string description;
+    int32 participant_count = 0;
+    int32 administrator_count = 0;
+    int32 restricted_count = 0;
+    int32 banned_count = 0;
+    string invite_link;
+    MessageId pinned_message_id;
+
+    int64 sticker_set_id = 0;  // do not forget to store along with access hash
+
+    MessageId migrated_from_max_message_id;
+    ChatId migrated_from_chat_id;
+
+    bool can_get_participants = false;
+    bool can_set_username = false;
+    bool can_set_sticker_set = false;
+    bool is_all_history_available = true;
+
+    bool is_changed = true;
+
+    double expires_at = 0.0;
+    bool is_expired() const;
+  };
+
+  struct SecretChat {
+    int64 access_hash = 0;
+    UserId user_id;
+    SecretChatState state;
+    string key_hash;
+    int32 ttl = 0;
+    int32 date = 0;
+    int32 layer = 0;
+
+    bool is_outbound = false;
+
+    bool is_changed = true;        // have new changes not sent to the database except changes visible to the client
+    bool need_send_update = true;  // have new changes not sent to the client
+
+    bool is_saved = false;        // is current secret chat version being saved/is saved to the database
+    bool is_being_saved = false;  // is current secret chat being saved to the database
+    uint64 logevent_id = 0;
+
+    template <class StorerT>
+    void store(StorerT &storer) const;
+
+    template <class ParserT>
+    void parse(ParserT &parser);
+  };
+
+  struct InviteLinkInfo {
+    ChatId chat_id;  // TODO DialogId
+    ChannelId channel_id;
+    string title;
+    DialogPhoto photo;
+    int32 participant_count = 0;
+    vector<UserId> participant_user_ids;
+
+    bool is_chat = false;
+    bool is_channel = false;
+    bool is_public = false;
+    bool is_megagroup = false;
+  };
+
+  class UserLogEvent;
+  class ChatLogEvent;
+  class ChannelLogEvent;
+  class SecretChatLogEvent;
+
+  static constexpr int32 MAX_GET_PROFILE_PHOTOS = 100;  // server side limit
+  static constexpr size_t MAX_NAME_LENGTH = 255;        // server side limit for first/last name and title
+  static constexpr size_t MAX_BIO_LENGTH = 70;          // server side limit
+
+  static constexpr int32 USER_FLAG_HAS_ACCESS_HASH = 1 << 0;
+  static constexpr int32 USER_FLAG_HAS_FIRST_NAME = 1 << 1;
+  static constexpr int32 USER_FLAG_HAS_LAST_NAME = 1 << 2;
+  static constexpr int32 USER_FLAG_HAS_USERNAME = 1 << 3;
+  static constexpr int32 USER_FLAG_HAS_PHONE_NUMBER = 1 << 4;
+  static constexpr int32 USER_FLAG_HAS_PHOTO = 1 << 5;
+  static constexpr int32 USER_FLAG_HAS_STATUS = 1 << 6;
+  static constexpr int32 USER_FLAG_HAS_BOT_INFO_VERSION = 1 << 14;
+  static constexpr int32 USER_FLAG_IS_ME = 1 << 10;
+  static constexpr int32 USER_FLAG_IS_CONTACT = 1 << 11;
+  static constexpr int32 USER_FLAG_IS_MUTUAL_CONTACT = 1 << 12;
+  static constexpr int32 USER_FLAG_IS_DELETED = 1 << 13;
+  static constexpr int32 USER_FLAG_IS_BOT = 1 << 14;
+  static constexpr int32 USER_FLAG_IS_BOT_WITH_PRIVACY_DISABLED = 1 << 15;
+  static constexpr int32 USER_FLAG_IS_PRIVATE_BOT = 1 << 16;
+  static constexpr int32 USER_FLAG_IS_VERIFIED = 1 << 17;
+  static constexpr int32 USER_FLAG_IS_RESTRICTED = 1 << 18;
+  static constexpr int32 USER_FLAG_IS_INLINE_BOT = 1 << 19;
+  static constexpr int32 USER_FLAG_IS_INACCESSIBLE = 1 << 20;
+  static constexpr int32 USER_FLAG_NEED_LOCATION_BOT = 1 << 21;
+  static constexpr int32 USER_FLAG_HAS_LANGUAGE_CODE = 1 << 22;
+
+  static constexpr int32 USER_FULL_FLAG_IS_BLOCKED = 1 << 0;
+  static constexpr int32 USER_FULL_FLAG_HAS_ABOUT = 1 << 1;
+  static constexpr int32 USER_FULL_FLAG_HAS_PHOTO = 1 << 2;
+  static constexpr int32 USER_FULL_FLAG_HAS_BOT_INFO = 1 << 3;
+
+  static constexpr int32 CHAT_FLAG_USER_IS_CREATOR = 1 << 0;
+  static constexpr int32 CHAT_FLAG_USER_WAS_KICKED = 1 << 1;
+  static constexpr int32 CHAT_FLAG_USER_HAS_LEFT = 1 << 2;
+  static constexpr int32 CHAT_FLAG_ADMINISTRATORS_ENABLED = 1 << 3;
+  static constexpr int32 CHAT_FLAG_IS_ADMINISTRATOR = 1 << 4;
+  static constexpr int32 CHAT_FLAG_IS_DEACTIVATED = 1 << 5;
+  static constexpr int32 CHAT_FLAG_WAS_MIGRATED = 1 << 6;
+
+  static constexpr int32 CHANNEL_FLAG_USER_IS_CREATOR = 1 << 0;
+  static constexpr int32 CHANNEL_FLAG_USER_HAS_LEFT = 1 << 2;
+  static constexpr int32 CHANNEL_FLAG_IS_BROADCAST = 1 << 5;
+  static constexpr int32 CHANNEL_FLAG_IS_PUBLIC = 1 << 6;
+  static constexpr int32 CHANNEL_FLAG_IS_VERIFIED = 1 << 7;
+  static constexpr int32 CHANNEL_FLAG_IS_MEGAGROUP = 1 << 8;
+  static constexpr int32 CHANNEL_FLAG_IS_RESTRICTED = 1 << 9;
+  static constexpr int32 CHANNEL_FLAG_ANYONE_CAN_INVITE = 1 << 10;
+  static constexpr int32 CHANNEL_FLAG_SIGN_MESSAGES = 1 << 11;
+  static constexpr int32 CHANNEL_FLAG_IS_MIN = 1 << 12;
+  static constexpr int32 CHANNEL_FLAG_HAS_ACCESS_HASH = 1 << 13;
+  static constexpr int32 CHANNEL_FLAG_HAS_ADMIN_RIGHTS = 1 << 14;
+  static constexpr int32 CHANNEL_FLAG_HAS_BANNED_RIGHTS = 1 << 15;
+  static constexpr int32 CHANNEL_FLAG_HAS_UNBAN_DATE = 1 << 16;
+  static constexpr int32 CHANNEL_FLAG_HAS_PARTICIPANT_COUNT = 1 << 17;
+
+  static constexpr int32 CHANNEL_FULL_FLAG_HAS_PARTICIPANT_COUNT = 1 << 0;
+  static constexpr int32 CHANNEL_FULL_FLAG_HAS_ADMINISTRATOR_COUNT = 1 << 1;
+  static constexpr int32 CHANNEL_FULL_FLAG_HAS_BANNED_COUNT = 1 << 2;
+  static constexpr int32 CHANNEL_FULL_FLAG_CAN_GET_PARTICIPANTS = 1 << 3;
+  static constexpr int32 CHANNEL_FULL_FLAG_MIGRATED_FROM = 1 << 4;
+  static constexpr int32 CHANNEL_FULL_FLAG_HAS_PINNED_MESSAGE = 1 << 5;
+  static constexpr int32 CHANNEL_FULL_FLAG_CAN_SET_USERNAME = 1 << 6;
+  static constexpr int32 CHANNEL_FULL_FLAG_CAN_SET_STICKERS = 1 << 7;
+  static constexpr int32 CHANNEL_FULL_FLAG_HAS_STICKER_SET = 1 << 8;
+  static constexpr int32 CHANNEL_FULL_FLAG_HAS_AVAILABLE_MIN_MESSAGE_ID = 1 << 9;
+  static constexpr int32 CHANNEL_FULL_FLAG_IS_ALL_HISTORY_HIDDEN = 1 << 10;
+
+  static constexpr int32 CHAT_INVITE_FLAG_IS_CHANNEL = 1 << 0;
+  static constexpr int32 CHAT_INVITE_FLAG_IS_BROADCAST = 1 << 1;
+  static constexpr int32 CHAT_INVITE_FLAG_IS_PUBLIC = 1 << 2;
+  static constexpr int32 CHAT_INVITE_FLAG_IS_MEGAGROUP = 1 << 3;
+  static constexpr int32 CHAT_INVITE_FLAG_HAS_USERS = 1 << 4;
+
+  static constexpr int32 USER_FULL_EXPIRE_TIME = 60;
+  static constexpr int32 CHANNEL_FULL_EXPIRE_TIME = 60;
+
+  static constexpr int32 ACCOUNT_UPDATE_FIRST_NAME = 1 << 0;
+  static constexpr int32 ACCOUNT_UPDATE_LAST_NAME = 1 << 1;
+  static constexpr int32 ACCOUNT_UPDATE_ABOUT = 1 << 2;
+
+  static const CSlice INVITE_LINK_URLS[3];
+
+  static bool have_input_peer_user(const User *user, AccessRights access_rights);
+  static bool have_input_peer_chat(const Chat *chat, AccessRights access_rights);
+  static bool have_input_peer_channel(const Channel *c, AccessRights access_rights);
+  static bool have_input_encrypted_peer(const SecretChat *secret_chat, AccessRights access_rights);
+
+  const User *get_user(UserId user_id) const;
+  User *get_user(UserId user_id);
+  User *get_user_force(UserId user_id);
+
+  User *add_user(UserId user_id);
+
+  const UserFull *get_user_full(UserId user_id) const;
+  UserFull *get_user_full(UserId user_id);
+
+  void send_get_user_full_query(UserId user_id, tl_object_ptr<telegram_api::InputUser> &&input_user,
+                                Promise<Unit> &&promise);
+
+  const Chat *get_chat(ChatId chat_id) const;
+  Chat *get_chat(ChatId chat_id);
+  Chat *get_chat_force(ChatId chat_id);
+
+  Chat *add_chat(ChatId chat_id);
+
+  const ChatFull *get_chat_full(ChatId chat_id) const;
+  ChatFull *get_chat_full(ChatId chat_id);
+
+  void send_get_chat_full_query(ChatId chat_id, Promise<Unit> &&promise);
+
+  const Channel *get_channel(ChannelId channel_id) const;
+  Channel *get_channel(ChannelId channel_id);
+  Channel *get_channel_force(ChannelId channel_id);
+
+  Channel *add_channel(ChannelId channel_id);
+
+  const ChannelFull *get_channel_full(ChannelId channel_id) const;
+  ChannelFull *get_channel_full(ChannelId channel_id);
+
+  void send_get_channel_full_query(ChannelId channel_id, tl_object_ptr<telegram_api::InputChannel> &&input_channel,
+                                   Promise<Unit> &&promise);
+
+  const SecretChat *get_secret_chat(SecretChatId secret_chat_id) const;
+  SecretChat *get_secret_chat(SecretChatId secret_chat_id);
+  SecretChat *get_secret_chat_force(SecretChatId secret_chat_id);
+
+  SecretChat *add_secret_chat(SecretChatId secret_chat_id);
+
+  static DialogParticipantStatus get_chat_status(const Chat *c);
+
+  static ChannelType get_channel_type(const Channel *c);
+  static DialogParticipantStatus get_channel_status(const Channel *c);
+  static bool get_channel_sign_messages(const Channel *c);
+
+  void set_my_id(UserId my_id);
+
+  static LinkState get_link_state(tl_object_ptr<telegram_api::ContactLink> &&link);
+
+  void repair_chat_participants(ChatId chat_id);
+
+  static bool is_valid_username(const string &username);
+
+  bool on_update_bot_info(tl_object_ptr<telegram_api::botInfo> &&bot_info);
+
+  void on_update_user_name(User *u, UserId user_id, string &&first_name, string &&last_name, string &&username);
+  void on_update_user_phone_number(User *u, UserId user_id, string &&phone_number);
+  void on_update_user_photo(User *u, UserId user_id, tl_object_ptr<telegram_api::UserProfilePhoto> &&photo_ptr);
+  void on_update_user_online(User *u, UserId user_id, tl_object_ptr<telegram_api::UserStatus> &&status);
+  void on_update_user_links(User *u, UserId user_id, LinkState outbound, LinkState inbound);
+
+  void on_update_user_full_is_blocked(UserFull *user_full, UserId user_id, bool is_blocked);
+  bool on_update_user_full_bot_info(UserFull *user_full, UserId user_id, int32 bot_info_version,
+                                    tl_object_ptr<telegram_api::botInfo> &&bot_info);
+  void invalidate_user_full(UserId user_id);
+
+  void on_update_chat_left(Chat *c, ChatId chat_id, bool left, bool kicked);
+  void on_update_chat_participant_count(Chat *c, ChatId chat_id, int32 participant_count, int32 version,
+                                        const string &debug_str);
+  void on_update_chat_photo(Chat *c, ChatId chat_id, tl_object_ptr<telegram_api::ChatPhoto> &&chat_photo_ptr);
+  void on_update_chat_rights(Chat *c, ChatId chat_id, bool is_creator, bool is_administrator,
+                             bool everyone_is_administrator);
+  void on_update_chat_title(Chat *c, ChatId chat_id, string &&title);
+  void on_update_chat_active(Chat *c, ChatId chat_id, bool is_active);
+  void on_update_chat_migrated_to_channel_id(Chat *c, ChatId chat_id, ChannelId migrated_to_channel_id);
+
+  bool on_update_chat_full_participants_short(ChatFull *chat_full, ChatId chat_id, int32 version);
+  void on_update_chat_full_participants(ChatFull *chat_full, ChatId chat_id, vector<DialogParticipant> participants,
+                                        int32 version);
+  void on_update_chat_full_invite_link(ChatFull *chat_full,
+                                       tl_object_ptr<telegram_api::ExportedChatInvite> &&invite_link_ptr);
+
+  void on_update_channel_photo(Channel *c, ChannelId channel_id,
+                               tl_object_ptr<telegram_api::ChatPhoto> &&chat_photo_ptr);
+  void on_update_channel_title(Channel *c, ChannelId channel_id, string &&title);
+  void on_update_channel_username(Channel *c, ChannelId channel_id, string &&username);
+  void on_update_channel_status(Channel *c, ChannelId channel_id, DialogParticipantStatus &&status);
+
+  void on_update_channel_full_invite_link(ChannelFull *channel_full,
+                                          tl_object_ptr<telegram_api::ExportedChatInvite> &&invite_link_ptr);
+  void on_update_channel_full_pinned_message(ChannelFull *channel_full, MessageId message_id);
+
+  void speculative_add_channel_users(ChannelId channel_id, DialogParticipantStatus status,
+                                     DialogParticipantStatus old_status);
+
+  void invalidate_chat_full(ChatId chat_id);
+
+  void on_chat_update(telegram_api::chatEmpty &chat);
+  void on_chat_update(telegram_api::chat &chat);
+  void on_chat_update(telegram_api::chatForbidden &chat);
+  void on_chat_update(telegram_api::channel &channel);
+  void on_chat_update(telegram_api::channelForbidden &channel);
+
+  void save_user(User *u, UserId user_id, bool from_binlog);
+  static string get_user_database_key(UserId user_id);
+  static string get_user_database_value(const User *u);
+  void save_user_to_database(User *u, UserId user_id);
+  void save_user_to_database_impl(User *u, UserId user_id, string value);
+  void on_save_user_to_database(UserId user_id, bool success);
+  void load_user_from_database(User *u, UserId user_id, Promise<Unit> promise);
+  void load_user_from_database_impl(UserId user_id, Promise<Unit> promise);
+  void on_load_user_from_database(UserId user_id, string value);
+
+  void save_chat(Chat *c, ChatId chat_id, bool from_binlog);
+  static string get_chat_database_key(ChatId chat_id);
+  static string get_chat_database_value(const Chat *c);
+  void save_chat_to_database(Chat *c, ChatId chat_id);
+  void save_chat_to_database_impl(Chat *c, ChatId chat_id, string value);
+  void on_save_chat_to_database(ChatId chat_id, bool success);
+  void load_chat_from_database(Chat *c, ChatId chat_id, Promise<Unit> promise);
+  void load_chat_from_database_impl(ChatId chat_id, Promise<Unit> promise);
+  void on_load_chat_from_database(ChatId chat_id, string value);
+
+  void save_channel(Channel *c, ChannelId channel_id, bool from_binlog);
+  static string get_channel_database_key(ChannelId channel_id);
+  static string get_channel_database_value(const Channel *c);
+  void save_channel_to_database(Channel *c, ChannelId channel_id);
+  void save_channel_to_database_impl(Channel *c, ChannelId channel_id, string value);
+  void on_save_channel_to_database(ChannelId channel_id, bool success);
+  void load_channel_from_database(Channel *c, ChannelId channel_id, Promise<Unit> promise);
+  void load_channel_from_database_impl(ChannelId channel_id, Promise<Unit> promise);
+  void on_load_channel_from_database(ChannelId channel_id, string value);
+
+  void save_secret_chat(SecretChat *c, SecretChatId secret_chat_id, bool from_binlog);
+  static string get_secret_chat_database_key(SecretChatId secret_chat_id);
+  static string get_secret_chat_database_value(const SecretChat *c);
+  void save_secret_chat_to_database(SecretChat *c, SecretChatId secret_chat_id);
+  void save_secret_chat_to_database_impl(SecretChat *c, SecretChatId secret_chat_id, string value);
+  void on_save_secret_chat_to_database(SecretChatId secret_chat_id, bool success);
+  void load_secret_chat_from_database(SecretChat *c, SecretChatId secret_chat_id, Promise<Unit> promise);
+  void load_secret_chat_from_database_impl(SecretChatId secret_chat_id, Promise<Unit> promise);
+  void on_load_secret_chat_from_database(SecretChatId secret_chat_id, string value);
+
+  void update_user(User *u, UserId user_id, bool from_binlog = false, bool from_database = false);
+  void update_chat(Chat *c, ChatId chat_id, bool from_binlog = false, bool from_database = false);
+  void update_channel(Channel *c, ChannelId channel_id, bool from_binlog = false, bool from_database = false);
+  void update_secret_chat(SecretChat *c, SecretChatId secret_chat_id, bool from_binlog = false,
+                          bool from_database = false);
+
+  void update_user_full(UserFull *user_full, UserId user_id);
+  void update_chat_full(ChatFull *chat_full, ChatId chat_id);
+  void update_channel_full(ChannelFull *channel_full, ChannelId channel_id);
+
+  bool is_chat_full_outdated(ChatFull *chat_full, Chat *c, ChatId chat_id);
+
+  int32 get_contacts_hash();
+
+  void update_contacts_hints(const User *u, UserId user_id, bool from_database);
+
+  void save_next_contacts_sync_date();
+
+  void save_contacts_to_database();
+
+  void load_contacts(Promise<Unit> &&promise);
+
+  void on_load_contacts_from_database(string value);
+
+  void on_get_contacts_finished(size_t expected_contact_count);
+
+  void load_imported_contacts(Promise<Unit> &&promise);
+
+  void on_load_imported_contacts_from_database(string value);
+
+  void on_load_imported_contacts_finished();
+
+  void on_clear_imported_contacts(vector<Contact> &&contacts, vector<size_t> contacts_unique_id,
+                                  std::pair<vector<size_t>, vector<Contact>> &&to_add, Promise<Unit> &&promise);
+
+  static bool is_valid_invite_link(const string &invite_link);
+
+  bool update_invite_link(string &invite_link, tl_object_ptr<telegram_api::ExportedChatInvite> &&invite_link_ptr);
+
+  const DialogParticipant *get_chat_participant(ChatId chat_id, UserId user_id) const;
+
+  const DialogParticipant *get_chat_participant(const ChatFull *chat_full, UserId user_id) const;
+
+  static string get_dialog_administrators_database_key(DialogId dialog_id);
+
+  void load_dialog_administrators(DialogId dialog_id, Promise<Unit> &&promise);
+
+  void on_load_dialog_administrators_from_database(DialogId dialog_id, string value, Promise<Unit> &&promise);
+
+  void on_load_administrator_users_finished(DialogId dialog_id, vector<UserId> user_ids, Result<> result,
+                                            Promise<Unit> promise);
+
+  void reload_dialog_administrators(DialogId dialog_id, int32 hash, Promise<Unit> &&promise);
+
+  tl_object_ptr<td_api::UserStatus> get_user_status_object(UserId user_id, const User *u) const;
+
+  static tl_object_ptr<td_api::LinkState> get_link_state_object(LinkState link);
+
+  static tl_object_ptr<td_api::botInfo> get_bot_info_object(const BotInfo *bot_info);
+
+  tl_object_ptr<td_api::user> get_user_object(UserId user_id, const User *u) const;
+
+  tl_object_ptr<td_api::userFullInfo> get_user_full_info_object(UserId user_id, const UserFull *user_full) const;
+
+  tl_object_ptr<td_api::basicGroup> get_basic_group_object(ChatId chat_id, const Chat *chat);
+
+  tl_object_ptr<td_api::basicGroupFullInfo> get_basic_group_full_info_object(const ChatFull *chat_full) const;
+
+  tl_object_ptr<td_api::supergroup> get_supergroup_object(ChannelId channel_id, const Channel *channel) const;
+
+  tl_object_ptr<td_api::supergroupFullInfo> get_channel_full_info_object(const ChannelFull *channel_full) const;
+
+  static tl_object_ptr<td_api::SecretChatState> get_secret_chat_state_object(SecretChatState state);
+
+  tl_object_ptr<td_api::secretChat> get_secret_chat_object(SecretChatId secret_chat_id, const SecretChat *secret_chat);
+
+  void delete_chat_participant(ChatId chat_id, UserId user_id, Promise<Unit> &&promise);
+
+  void change_channel_participant_status_impl(ChannelId channel_id, UserId user_id, DialogParticipantStatus status,
+                                              DialogParticipantStatus old_status, Promise<Unit> &&promise);
+
+  void promote_channel_participant(ChannelId channel_id, UserId user_id, DialogParticipantStatus status,
+                                   DialogParticipantStatus old_status, Promise<Unit> &&promise);
+
+  void restrict_channel_participant(ChannelId channel_id, UserId user_id, DialogParticipantStatus status,
+                                    DialogParticipantStatus old_status, Promise<Unit> &&promise);
+
+  static void on_user_online_timeout_callback(void *contacts_manager_ptr, int64 user_id_long);
+
+  static void on_channel_unban_timeout_callback(void *contacts_manager_ptr, int64 channel_id_long);
+
+  template <class StorerT>
+  static void store_link_state(const LinkState &link_state, StorerT &storer);
+
+  template <class ParserT>
+  static void parse_link_state(LinkState &link_state, ParserT &parser);
+
+  void tear_down() override;
+
+  Td *td_;
+  ActorShared<> parent_;
+  UserId my_id_;
+  UserId support_user_id_;
+  int32 my_was_online_local_ = 0;
+
+  std::unordered_map<UserId, User, UserIdHash> users_;
+  std::unordered_map<UserId, UserFull, UserIdHash> users_full_;
+  mutable std::unordered_set<UserId, UserIdHash> unknown_users_;
+
+  std::unordered_map<ChatId, Chat, ChatIdHash> chats_;
+  std::unordered_map<ChatId, ChatFull, ChatIdHash> chats_full_;
+  mutable std::unordered_set<ChatId, ChatIdHash> unknown_chats_;
+
+  std::unordered_set<ChannelId, ChannelIdHash> min_channels_;
+  std::unordered_map<ChannelId, Channel, ChannelIdHash> channels_;
+  std::unordered_map<ChannelId, ChannelFull, ChannelIdHash> channels_full_;
+  mutable std::unordered_set<ChannelId, ChannelIdHash> unknown_channels_;
+
+  std::unordered_map<SecretChatId, SecretChat, SecretChatIdHash> secret_chats_;
+  mutable std::unordered_set<SecretChatId, SecretChatIdHash> unknown_secret_chats_;
+
+  std::unordered_map<UserId, vector<SecretChatId>, UserIdHash> secret_chats_with_user_;
+
+  std::unordered_map<ChatId, string, ChatIdHash> chat_invite_links_;           // in-memory cache for invite links
+  std::unordered_map<ChannelId, string, ChannelIdHash> channel_invite_links_;  // in-memory cache for invite links
+  std::unordered_map<string, unique_ptr<InviteLinkInfo>> invite_link_infos_;
+
+  bool created_public_channels_inited_ = false;
+  vector<ChannelId> created_public_channels_;
+
+  std::unordered_map<UserId, vector<Promise<Unit>>, UserIdHash> load_user_from_database_queries_;
+  std::unordered_set<UserId, UserIdHash> loaded_from_database_users_;
+
+  std::unordered_map<ChatId, vector<Promise<Unit>>, ChatIdHash> load_chat_from_database_queries_;
+  std::unordered_set<ChatId, ChatIdHash> loaded_from_database_chats_;
+
+  std::unordered_map<ChannelId, vector<Promise<Unit>>, ChannelIdHash> load_channel_from_database_queries_;
+  std::unordered_set<ChannelId, ChannelIdHash> loaded_from_database_channels_;
+
+  std::unordered_map<SecretChatId, vector<Promise<Unit>>, SecretChatIdHash> load_secret_chat_from_database_queries_;
+  std::unordered_set<SecretChatId, SecretChatIdHash> loaded_from_database_secret_chats_;
+
+  std::unordered_map<UserId, vector<Promise<Unit>>, UserIdHash> get_user_full_queries_;
+  std::unordered_map<ChatId, vector<Promise<Unit>>, ChatIdHash> get_chat_full_queries_;
+  std::unordered_map<ChannelId, vector<Promise<Unit>>, ChannelIdHash> get_channel_full_queries_;
+
+  std::unordered_map<DialogId, vector<UserId>, DialogIdHash> dialog_administrators_;
+
+  class UploadProfilePhotoCallback;
+  std::shared_ptr<UploadProfilePhotoCallback> upload_profile_photo_callback_;
+
+  std::unordered_map<FileId, Promise<Unit>, FileIdHash> uploaded_profile_photos_;  // file_id -> promise
+
+  std::unordered_map<int64, std::pair<vector<UserId>, vector<int32>>> imported_contacts_;
+
+  std::unordered_map<int64, DialogParticipant> received_channel_participant_;
+  std::unordered_map<int64, std::pair<int32, vector<DialogParticipant>>> received_channel_participants_;
+
+  std::unordered_map<int64, std::pair<int32, vector<UserId>>>
+      found_blocked_users_;  // random_id -> [total_count, [user_id]...]
+
+  bool are_contacts_loaded_ = false;
+  int32 next_contacts_sync_date_ = 0;
+  Hints contacts_hints_;  // search contacts by first name, last name and username
+  vector<Promise<Unit>> load_contacts_queries_;
+  MultiPromiseActor load_contact_users_multipromise_;
+  int32 saved_contact_count_ = -1;
+
+  bool are_imported_contacts_loaded_ = false;
+  vector<Promise<Unit>> load_imported_contacts_queries_;
+  MultiPromiseActor load_imported_contact_users_multipromise_;
+  vector<Contact> all_imported_contacts_;
+  bool are_imported_contacts_changing_ = false;
+
+  vector<Contact> next_all_imported_contacts_;
+  vector<size_t> imported_contacts_unique_id_;
+  vector<size_t> imported_contacts_pos_;
+
+  vector<UserId> imported_contact_user_ids_;  // result of change_imported_contacts
+  vector<int32> unimported_contact_invites_;  // result of change_imported_contacts
+
+  MultiTimeout user_online_timeout_;
+  MultiTimeout channel_unban_timeout_;
+
+  class OnChatUpdate;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/DelayDispatcher.cpp b/libs/tdlib/td/td/telegram/DelayDispatcher.cpp
new file mode 100644
index 0000000000..130d3c6615
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/DelayDispatcher.cpp
@@ -0,0 +1,46 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/DelayDispatcher.h"
+
+#include "td/telegram/Global.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+
+namespace td {
+
+void DelayDispatcher::send_with_callback(NetQueryPtr query, ActorShared<NetQueryCallback> callback) {
+  send_with_callback_and_delay(std::move(query), std::move(callback), default_delay_);
+}
+void DelayDispatcher::send_with_callback_and_delay(NetQueryPtr query, ActorShared<NetQueryCallback> callback,
+                                                   double delay) {
+  queue_.push({std::move(query), std::move(callback), delay});
+  loop();
+}  // namespace td
+
+void DelayDispatcher::loop() {
+  if (!wakeup_at_.is_in_past()) {
+    set_timeout_at(wakeup_at_.at());
+    return;
+  }
+
+  if (queue_.empty()) {
+    return;
+  }
+
+  auto query = std::move(queue_.front());
+  queue_.pop();
+  G()->net_query_dispatcher().dispatch_with_callback(std::move(query.net_query), std::move(query.callback));
+
+  wakeup_at_ = Timestamp::in(query.delay);
+
+  if (queue_.empty()) {
+    return;
+  }
+
+  set_timeout_at(wakeup_at_.at());
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/DelayDispatcher.h b/libs/tdlib/td/td/telegram/DelayDispatcher.h
new file mode 100644
index 0000000000..42e836b283
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/DelayDispatcher.h
@@ -0,0 +1,40 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/actor/actor.h"
+
+#include "td/utils/Time.h"
+
+#include <queue>
+
+namespace td {
+
+class DelayDispatcher : public Actor {
+ public:
+  explicit DelayDispatcher(double default_delay) : default_delay_(default_delay) {
+  }
+
+  void send_with_callback(NetQueryPtr query, ActorShared<NetQueryCallback> callback);
+  void send_with_callback_and_delay(NetQueryPtr query, ActorShared<NetQueryCallback> callback, double delay);
+
+ private:
+  struct Query {
+    NetQueryPtr net_query;
+    ActorShared<NetQueryCallback> callback;
+    double delay;
+  };
+  std::queue<Query> queue_;
+  Timestamp wakeup_at_;
+  double default_delay_;
+
+  void loop() override;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/DeviceTokenManager.cpp b/libs/tdlib/td/td/telegram/DeviceTokenManager.cpp
new file mode 100644
index 0000000000..8182d6dac8
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/DeviceTokenManager.cpp
@@ -0,0 +1,383 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/DeviceTokenManager.h"
+
+#include "td/telegram/Global.h"
+#include "td/telegram/misc.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+#include "td/telegram/UserId.h"
+
+#include "td/telegram/td_api.hpp"
+#include "td/telegram/telegram_api.h"
+
+#include "td/utils/base64.h"
+#include "td/utils/buffer.h"
+#include "td/utils/format.h"
+#include "td/utils/JsonBuilder.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/tl_helpers.h"
+
+#include <type_traits>
+
+namespace td {
+
+template <class StorerT>
+void DeviceTokenManager::TokenInfo::store(StorerT &storer) const {
+  using td::store;
+  bool has_other_user_ids = !other_user_ids.empty();
+  bool is_sync = state == State::Sync;
+  bool is_unregister = state == State::Unregister;
+  bool is_register = state == State::Register;
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(has_other_user_ids);
+  STORE_FLAG(is_sync);
+  STORE_FLAG(is_unregister);
+  STORE_FLAG(is_register);
+  STORE_FLAG(is_app_sandbox);
+  END_STORE_FLAGS();
+  store(token, storer);
+  if (has_other_user_ids) {
+    store(other_user_ids, storer);
+  }
+}
+
+template <class ParserT>
+void DeviceTokenManager::TokenInfo::parse(ParserT &parser) {
+  using td::parse;
+  bool has_other_user_ids;
+  bool is_sync;
+  bool is_unregister;
+  bool is_register;
+  BEGIN_PARSE_FLAGS();
+  PARSE_FLAG(has_other_user_ids);
+  PARSE_FLAG(is_sync);
+  PARSE_FLAG(is_unregister);
+  PARSE_FLAG(is_register);
+  PARSE_FLAG(is_app_sandbox);
+  END_PARSE_FLAGS();
+  CHECK(is_sync + is_unregister + is_register == 1);
+  if (is_sync) {
+    state = State::Sync;
+  } else if (is_unregister) {
+    state = State::Unregister;
+  } else {
+    state = State::Register;
+  }
+  parse(token, parser);
+  if (has_other_user_ids) {
+    parse(other_user_ids, parser);
+  }
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const DeviceTokenManager::TokenInfo &token_info) {
+  switch (token_info.state) {
+    case DeviceTokenManager::TokenInfo::State::Sync:
+      string_builder << "Synchronized";
+      break;
+    case DeviceTokenManager::TokenInfo::State::Unregister:
+      string_builder << "Unregister";
+      break;
+    case DeviceTokenManager::TokenInfo::State::Register:
+      string_builder << "Register";
+      break;
+    default:
+      UNREACHABLE();
+  }
+  string_builder << " token \"" << format::escaped(token_info.token) << "\"";
+  if (!token_info.other_user_ids.empty()) {
+    string_builder << ", with other users " << token_info.other_user_ids;
+  }
+  if (token_info.is_app_sandbox) {
+    string_builder << ", sandboxed";
+  }
+  return string_builder;
+}
+
+void DeviceTokenManager::register_device(tl_object_ptr<td_api::DeviceToken> device_token_ptr,
+                                         vector<int32> other_user_ids, Promise<tl_object_ptr<td_api::ok>> promise) {
+  CHECK(device_token_ptr != nullptr);
+  TokenType token_type;
+  string token;
+  bool is_app_sandbox = false;
+  switch (device_token_ptr->get_id()) {
+    case td_api::deviceTokenApplePush::ID: {
+      auto device_token = static_cast<td_api::deviceTokenApplePush *>(device_token_ptr.get());
+      token = std::move(device_token->device_token_);
+      token_type = TokenType::APNS;
+      is_app_sandbox = device_token->is_app_sandbox_;
+      break;
+    }
+    case td_api::deviceTokenGoogleCloudMessaging::ID: {
+      auto device_token = static_cast<td_api::deviceTokenGoogleCloudMessaging *>(device_token_ptr.get());
+      token = std::move(device_token->token_);
+      token_type = TokenType::GCM;
+      break;
+    }
+    case td_api::deviceTokenMicrosoftPush::ID: {
+      auto device_token = static_cast<td_api::deviceTokenMicrosoftPush *>(device_token_ptr.get());
+      token = std::move(device_token->channel_uri_);
+      token_type = TokenType::MPNS;
+      break;
+    }
+    case td_api::deviceTokenSimplePush::ID: {
+      auto device_token = static_cast<td_api::deviceTokenSimplePush *>(device_token_ptr.get());
+      token = std::move(device_token->endpoint_);
+      token_type = TokenType::SIMPLE_PUSH;
+      break;
+    }
+    case td_api::deviceTokenUbuntuPush::ID: {
+      auto device_token = static_cast<td_api::deviceTokenUbuntuPush *>(device_token_ptr.get());
+      token = std::move(device_token->token_);
+      token_type = TokenType::UBUNTU_PHONE;
+      break;
+    }
+    case td_api::deviceTokenBlackBerryPush::ID: {
+      auto device_token = static_cast<td_api::deviceTokenBlackBerryPush *>(device_token_ptr.get());
+      token = std::move(device_token->token_);
+      token_type = TokenType::BLACKBERRY;
+      break;
+    }
+    case td_api::deviceTokenWindowsPush::ID: {
+      auto device_token = static_cast<td_api::deviceTokenWindowsPush *>(device_token_ptr.get());
+      token = std::move(device_token->access_token_);
+      token_type = TokenType::WNS;
+      break;
+    }
+    case td_api::deviceTokenApplePushVoIP::ID: {
+      auto device_token = static_cast<td_api::deviceTokenApplePushVoIP *>(device_token_ptr.get());
+      token = std::move(device_token->device_token_);
+      token_type = TokenType::APNS_VOIP;
+      is_app_sandbox = device_token->is_app_sandbox_;
+      break;
+    }
+    case td_api::deviceTokenWebPush::ID: {
+      auto device_token = static_cast<td_api::deviceTokenWebPush *>(device_token_ptr.get());
+      if (device_token->endpoint_.find(',') != string::npos) {
+        return promise.set_error(Status::Error(400, "Illegal endpoint value"));
+      }
+      if (!is_base64url(device_token->p256dh_base64url_)) {
+        return promise.set_error(Status::Error(400, "Public key must be base64url-encoded"));
+      }
+      if (!is_base64url(device_token->auth_base64url_)) {
+        return promise.set_error(Status::Error(400, "Authentication secret must be base64url-encoded"));
+      }
+      if (!clean_input_string(device_token->endpoint_)) {
+        return promise.set_error(Status::Error(400, "Endpoint must be encoded in UTF-8"));
+      }
+
+      if (!device_token->endpoint_.empty()) {
+        class JsonKeys : public Jsonable {
+         public:
+          JsonKeys(Slice p256dh, Slice auth) : p256dh_(p256dh), auth_(auth) {
+          }
+          void store(JsonValueScope *scope) const {
+            auto object = scope->enter_object();
+            object << ctie("p256dh", p256dh_);
+            object << ctie("auth", auth_);
+          }
+
+         private:
+          Slice p256dh_;
+          Slice auth_;
+        };
+        class JsonWebPushToken : public Jsonable {
+         public:
+          JsonWebPushToken(Slice endpoint, Slice p256dh, Slice auth)
+              : endpoint_(endpoint), p256dh_(p256dh), auth_(auth) {
+          }
+          void store(JsonValueScope *scope) const {
+            auto object = scope->enter_object();
+            object << ctie("endpoint", endpoint_);
+            object << ctie("keys", JsonKeys(p256dh_, auth_));
+          }
+
+         private:
+          Slice endpoint_;
+          Slice p256dh_;
+          Slice auth_;
+        };
+
+        token = json_encode<string>(
+            JsonWebPushToken(device_token->endpoint_, device_token->p256dh_base64url_, device_token->auth_base64url_));
+      }
+      token_type = TokenType::WEB_PUSH;
+      break;
+    }
+    case td_api::deviceTokenMicrosoftPushVoIP::ID: {
+      auto device_token = static_cast<td_api::deviceTokenMicrosoftPushVoIP *>(device_token_ptr.get());
+      token = std::move(device_token->channel_uri_);
+      token_type = TokenType::MPNS_VOIP;
+      break;
+    }
+    case td_api::deviceTokenTizenPush::ID: {
+      auto device_token = static_cast<td_api::deviceTokenTizenPush *>(device_token_ptr.get());
+      token = std::move(device_token->reg_id_);
+      token_type = TokenType::TIZEN;
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+
+  if (!clean_input_string(token)) {
+    return promise.set_error(Status::Error(400, "Device token must be encoded in UTF-8"));
+  }
+  for (auto &other_user_id : other_user_ids) {
+    UserId user_id(other_user_id);
+    if (!user_id.is_valid()) {
+      return promise.set_error(Status::Error(400, "Invalid user_id among other user_ids"));
+    }
+  }
+  if (other_user_ids.size() > MAX_OTHER_USER_IDS) {
+    return promise.set_error(Status::Error(400, "Too much other user_ids"));
+  }
+
+  auto &info = tokens_[token_type];
+  info.net_query_id = 0;
+  if (token.empty()) {
+    if (info.token.empty()) {
+      // already unregistered
+      return promise.set_value(make_tl_object<td_api::ok>());
+    }
+
+    info.state = TokenInfo::State::Unregister;
+  } else {
+    info.state = TokenInfo::State::Register;
+    info.token = std::move(token);
+  }
+  info.other_user_ids = std::move(other_user_ids);
+  info.is_app_sandbox = is_app_sandbox;
+  info.promise.set_value(make_tl_object<td_api::ok>());
+  info.promise = std::move(promise);
+  save_info(token_type);
+}
+
+string DeviceTokenManager::get_database_key(int32 token_type) {
+  return PSTRING() << "device_token" << token_type;
+}
+
+void DeviceTokenManager::start_up() {
+  for (int32 token_type = 1; token_type < TokenType::SIZE; token_type++) {
+    auto serialized = G()->td_db()->get_binlog_pmc()->get(get_database_key(token_type));
+    if (serialized.empty()) {
+      continue;
+    }
+
+    auto &token = tokens_[token_type];
+    char c = serialized[0];
+    if (c == '*') {
+      unserialize(token, serialized.substr(1)).ensure();
+    } else {
+      // legacy
+      if (c == '+') {
+        token.state = TokenInfo::State::Register;
+      } else if (c == '-') {
+        token.state = TokenInfo::State::Unregister;
+      } else if (c == '=') {
+        token.state = TokenInfo::State::Sync;
+      } else {
+        LOG(ERROR) << "Invalid serialized TokenInfo: " << format::escaped(serialized);
+        continue;
+      }
+      token.token = serialized.substr(1);
+    }
+    LOG(INFO) << "GET device token " << token_type << "--->" << tokens_[token_type];
+  }
+  loop();
+}
+
+void DeviceTokenManager::save_info(int32 token_type) {
+  LOG(INFO) << "SET device token " << token_type << "--->" << tokens_[token_type];
+  if (tokens_[token_type].token.empty()) {
+    G()->td_db()->get_binlog_pmc()->erase(get_database_key(token_type));
+  } else {
+    G()->td_db()->get_binlog_pmc()->set(get_database_key(token_type), "*" + serialize(tokens_[token_type]));
+  }
+  sync_cnt_++;
+  G()->td_db()->get_binlog_pmc()->force_sync(
+      PromiseCreator::event(self_closure(this, &DeviceTokenManager::dec_sync_cnt)));
+}
+
+void DeviceTokenManager::dec_sync_cnt() {
+  sync_cnt_--;
+  loop();
+}
+
+void DeviceTokenManager::loop() {
+  if (sync_cnt_ != 0) {
+    return;
+  }
+  for (int32 token_type = 1; token_type < TokenType::SIZE; token_type++) {
+    auto &info = tokens_[token_type];
+    if (info.state == TokenInfo::State::Sync) {
+      continue;
+    }
+    if (info.net_query_id != 0) {
+      continue;
+    }
+    // have to send query
+    NetQueryPtr net_query;
+    auto other_user_ids = info.other_user_ids;
+    if (info.state == TokenInfo::State::Unregister) {
+      net_query = G()->net_query_creator().create(
+          create_storer(telegram_api::account_unregisterDevice(token_type, info.token, std::move(other_user_ids))));
+    } else {
+      net_query = G()->net_query_creator().create(create_storer(telegram_api::account_registerDevice(
+          token_type, info.token, info.is_app_sandbox, BufferSlice(), std::move(other_user_ids))));
+    }
+    info.net_query_id = net_query->id();
+    G()->net_query_dispatcher().dispatch_with_callback(std::move(net_query), actor_shared(this, token_type));
+  }
+}
+
+void DeviceTokenManager::on_result(NetQueryPtr net_query) {
+  auto token_type = static_cast<TokenType>(get_link_token());
+  CHECK(token_type >= 1 && token_type < TokenType::SIZE);
+  auto &info = tokens_[token_type];
+  if (info.net_query_id != net_query->id()) {
+    net_query->clear();
+    return;
+  }
+  info.net_query_id = 0;
+  static_assert(std::is_same<telegram_api::account_registerDevice::ReturnType,
+                             telegram_api::account_unregisterDevice::ReturnType>::value,
+                "");
+  auto r_flag = fetch_result<telegram_api::account_registerDevice>(std::move(net_query));
+
+  info.net_query_id = 0;
+  if (r_flag.is_ok() && r_flag.ok()) {
+    if (info.promise) {
+      info.promise.set_value(make_tl_object<td_api::ok>());
+    }
+    if (info.state == TokenInfo::State::Unregister) {
+      info.token = "";
+    }
+    info.state = TokenInfo::State::Sync;
+  } else {
+    if (info.promise) {
+      if (r_flag.is_error()) {
+        info.promise.set_error(r_flag.error().clone());
+      } else {
+        info.promise.set_error(Status::Error(5, "Got false as result"));
+      }
+    }
+    if (info.state == TokenInfo::State::Register) {
+      info.state = TokenInfo::State::Unregister;
+    } else {
+      info.state = TokenInfo::State::Sync;
+      info.token = "";
+    }
+    if (r_flag.is_error()) {
+      LOG(ERROR) << r_flag.error();
+    }
+  }
+  save_info(token_type);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/DeviceTokenManager.h b/libs/tdlib/td/td/telegram/DeviceTokenManager.h
new file mode 100644
index 0000000000..8858f85d7c
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/DeviceTokenManager.h
@@ -0,0 +1,81 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/telegram/td_api.h"
+
+#include "td/utils/common.h"
+#include "td/utils/StringBuilder.h"
+
+#include <array>
+
+namespace td {
+
+class DeviceTokenManager : public NetQueryCallback {
+ public:
+  explicit DeviceTokenManager(ActorShared<> parent) : parent_(std::move(parent)) {
+  }
+  void register_device(tl_object_ptr<td_api::DeviceToken> device_token_ptr, vector<int32> other_user_ids,
+                       Promise<tl_object_ptr<td_api::ok>> promise);
+
+ private:
+  static constexpr size_t MAX_OTHER_USER_IDS = 100;
+
+  ActorShared<> parent_;
+  enum TokenType : int32 {
+    APNS = 1,
+    GCM = 2,
+    MPNS = 3,
+    SIMPLE_PUSH = 4,
+    UBUNTU_PHONE = 5,
+    BLACKBERRY = 6,
+    UNUSED = 7,
+    WNS = 8,
+    APNS_VOIP = 9,
+    WEB_PUSH = 10,
+    MPNS_VOIP = 11,
+    TIZEN = 12,
+    SIZE
+  };
+  struct TokenInfo {
+    enum class State { Sync, Unregister, Register };
+    State state = State::Sync;
+    string token;
+    uint64 net_query_id = 0;
+    vector<int32> other_user_ids;
+    bool is_app_sandbox = false;
+    Promise<tl_object_ptr<td_api::ok>> promise;
+
+    template <class StorerT>
+    void store(StorerT &storer) const;
+
+    template <class ParserT>
+    void parse(ParserT &parser);
+  };
+
+  friend StringBuilder &operator<<(StringBuilder &string_builder, const TokenInfo &token_info);
+
+  std::array<TokenInfo, TokenType::SIZE> tokens_;
+  int32 sync_cnt_{0};
+
+  void start_up() override;
+
+  static string get_database_key(int32 token_type);
+  void save_info(int32 token_type);
+
+  void dec_sync_cnt();
+
+  void loop() override;
+  void on_result(NetQueryPtr net_query) override;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/DhCache.cpp b/libs/tdlib/td/td/telegram/DhCache.cpp
new file mode 100644
index 0000000000..23c299583d
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/DhCache.cpp
@@ -0,0 +1,44 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/DhCache.h"
+
+#include "td/db/Pmc.h"
+
+#include "td/telegram/Global.h"
+#include "td/telegram/TdDb.h"
+
+#include "td/utils/logging.h"
+
+namespace td {
+
+static string good_prime_key(Slice prime_str) {
+  string key("good_prime:");
+  key.append(prime_str.data(), prime_str.size());
+  return key;
+}
+
+int DhCache::is_good_prime(Slice prime_str) const {
+  string value = G()->td_db()->get_binlog_pmc()->get(good_prime_key(prime_str));
+  if (value == "good") {
+    return 1;
+  }
+  if (value == "bad") {
+    return 0;
+  }
+  CHECK(value == "");
+  return -1;
+}
+
+void DhCache::add_good_prime(Slice prime_str) const {
+  G()->td_db()->get_binlog_pmc()->set(good_prime_key(prime_str), "good");
+}
+
+void DhCache::add_bad_prime(Slice prime_str) const {
+  G()->td_db()->get_binlog_pmc()->set(good_prime_key(prime_str), "bad");
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/DhCache.h b/libs/tdlib/td/td/telegram/DhCache.h
new file mode 100644
index 0000000000..a2844a50b3
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/DhCache.h
@@ -0,0 +1,26 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/mtproto/crypto.h"
+
+#include "td/utils/Slice.h"
+
+namespace td {
+
+class DhCache : public DhCallback {
+ public:
+  int is_good_prime(Slice prime_str) const override;
+  void add_good_prime(Slice prime_str) const override;
+  void add_bad_prime(Slice prime_str) const override;
+
+  static DhCallback *instance() {
+    static DhCache res;
+    return &res;
+  }
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/DhConfig.h b/libs/tdlib/td/td/telegram/DhConfig.h
new file mode 100644
index 0000000000..a8a07e2e5a
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/DhConfig.h
@@ -0,0 +1,32 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/utils/common.h"
+
+namespace td {
+class DhConfig {
+ public:
+  int32 version = 0;
+  string prime;
+  int32 g = 0;
+  bool empty() const {
+    return prime.empty();
+  }
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    storer.store_int(version);
+    storer.store_string(prime);
+    storer.store_int(g);
+  }
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    version = parser.fetch_int();
+    prime = parser.template fetch_string<std::string>();
+    g = parser.fetch_int();
+  }
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/DialogDb.cpp b/libs/tdlib/td/td/telegram/DialogDb.cpp
new file mode 100644
index 0000000000..ea799bd529
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/DialogDb.cpp
@@ -0,0 +1,268 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/DialogDb.h"
+
+#include "td/telegram/Version.h"
+
+#include "td/db/SqliteDb.h"
+#include "td/db/SqliteKeyValue.h"
+#include "td/db/SqliteStatement.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Time.h"
+
+namespace td {
+// NB: must happen inside a transaction
+Status init_dialog_db(SqliteDb &db, int32 version, bool &was_created) {
+  LOG(INFO) << "Init dialog db " << tag("version", version);
+  was_created = false;
+
+  // Check if database exists
+  TRY_RESULT(has_table, db.has_table("dialogs"));
+  if (!has_table) {
+    version = 0;
+  }
+
+  if (version < static_cast<int32>(DbVersion::DialogDbCreated) || version > current_db_version()) {
+    TRY_STATUS(drop_dialog_db(db, version));
+    version = 0;
+  }
+
+  if (version == 0) {
+    LOG(INFO) << "Create new dialog db";
+    was_created = true;
+    TRY_STATUS(
+        db.exec("CREATE TABLE IF NOT EXISTS dialogs (dialog_id INT8 PRIMARY KEY, dialog_order INT8, data BLOB)"));
+    TRY_STATUS(db.exec("CREATE INDEX IF NOT EXISTS dialog_by_dialog_order ON dialogs (dialog_order, dialog_id)"));
+  }
+
+  return Status::OK();
+}
+
+// NB: must happen inside a transaction
+Status drop_dialog_db(SqliteDb &db, int version) {
+  if (version < static_cast<int32>(DbVersion::DialogDbCreated)) {
+    LOG(WARNING) << "Drop old pmc dialog_db";
+    SqliteKeyValue kv;
+    kv.init_with_connection(db.clone(), "common").ensure();
+    kv.erase_by_prefix("di");
+  }
+
+  LOG(WARNING) << "Drop dialog_db " << tag("version", version) << tag("current_db_version", current_db_version());
+  return db.exec("DROP TABLE IF EXISTS dialogs");
+}
+
+class DialogDbImpl : public DialogDbSyncInterface {
+ public:
+  explicit DialogDbImpl(SqliteDb db) : db_(std::move(db)) {
+    init().ensure();
+  }
+
+  Status init() {
+    TRY_RESULT(add_dialog_stmt, db_.get_statement("INSERT OR REPLACE INTO dialogs VALUES(?1, ?2, ?3)"));
+    TRY_RESULT(get_dialog_stmt, db_.get_statement("SELECT data FROM dialogs WHERE dialog_id = ?1"));
+    TRY_RESULT(get_dialogs_stmt, db_.get_statement("SELECT data, dialog_id, dialog_order FROM dialogs WHERE "
+                                                   "dialog_order < ?1 OR (dialog_order = ?1 AND dialog_id < ?2) ORDER "
+                                                   "BY dialog_order DESC, dialog_id DESC LIMIT ?3"));
+    /*
+        TRY_RESULT(get_dialogs2_stmt, db_.get_statement("SELECT data FROM dialogs WHERE dialog_order <= ?1 AND
+       (dialog_order != ?1 OR "
+                                                        "dialog_id < ?2) ORDER BY dialog_order, dialog_id DESC LIMIT
+       ?3"));
+    */
+    add_dialog_stmt_ = std::move(add_dialog_stmt);
+    get_dialog_stmt_ = std::move(get_dialog_stmt);
+    get_dialogs_stmt_ = std::move(get_dialogs_stmt);
+
+    // LOG(ERROR) << get_dialog_stmt_.explain().ok();
+    // LOG(ERROR) << get_dialogs_stmt_.explain().ok();
+    // LOG(ERROR) << get_dialogs2_stmt.explain().ok();
+    // LOG(FATAL) << "EPLAINED";
+
+    return Status::OK();
+  }
+
+  Status add_dialog(DialogId dialog_id, int64 order, BufferSlice data) override {
+    SCOPE_EXIT {
+      add_dialog_stmt_.reset();
+    };
+    add_dialog_stmt_.bind_int64(1, dialog_id.get()).ensure();
+    add_dialog_stmt_.bind_int64(2, order).ensure();
+    add_dialog_stmt_.bind_blob(3, data.as_slice()).ensure();
+    TRY_STATUS(add_dialog_stmt_.step());
+    return Status::OK();
+  }
+
+  Result<BufferSlice> get_dialog(DialogId dialog_id) override {
+    SCOPE_EXIT {
+      get_dialog_stmt_.reset();
+    };
+
+    get_dialog_stmt_.bind_int64(1, dialog_id.get()).ensure();
+    TRY_STATUS(get_dialog_stmt_.step());
+    if (!get_dialog_stmt_.has_row()) {
+      return Status::Error("Not found");
+    }
+    return BufferSlice(get_dialog_stmt_.view_blob(0));
+  }
+
+  Result<std::vector<BufferSlice>> get_dialogs(int64 order, DialogId dialog_id, int32 limit) override {
+    SCOPE_EXIT {
+      get_dialogs_stmt_.reset();
+    };
+
+    get_dialogs_stmt_.bind_int64(1, order).ensure();
+    get_dialogs_stmt_.bind_int64(2, dialog_id.get()).ensure();
+    get_dialogs_stmt_.bind_int32(3, limit).ensure();
+
+    std::vector<BufferSlice> dialogs;
+    TRY_STATUS(get_dialogs_stmt_.step());
+    while (get_dialogs_stmt_.has_row()) {
+      BufferSlice data(get_dialogs_stmt_.view_blob(0));
+      auto loaded_dialog_id = get_dialogs_stmt_.view_int64(1);
+      auto loaded_dialog_order = get_dialogs_stmt_.view_int64(2);
+      LOG(INFO) << "Load chat " << loaded_dialog_id << " with order " << loaded_dialog_order;
+      dialogs.emplace_back(std::move(data));
+      TRY_STATUS(get_dialogs_stmt_.step());
+    }
+
+    return std::move(dialogs);
+  }
+  Status begin_transaction() override {
+    return db_.begin_transaction();
+  }
+  Status commit_transaction() override {
+    return db_.commit_transaction();
+  }
+
+ private:
+  SqliteDb db_;
+
+  SqliteStatement add_dialog_stmt_;
+  SqliteStatement get_dialog_stmt_;
+  SqliteStatement get_dialogs_stmt_;
+};
+
+std::shared_ptr<DialogDbSyncSafeInterface> create_dialog_db_sync(
+    std::shared_ptr<SqliteConnectionSafe> sqlite_connection) {
+  class DialogDbSyncSafe : public DialogDbSyncSafeInterface {
+   public:
+    explicit DialogDbSyncSafe(std::shared_ptr<SqliteConnectionSafe> sqlite_connection)
+        : lsls_db_([safe_connection = std::move(sqlite_connection)] {
+          return std::make_unique<DialogDbImpl>(safe_connection->get().clone());
+        }) {
+    }
+    DialogDbSyncInterface &get() override {
+      return *lsls_db_.get();
+    }
+
+   private:
+    LazySchedulerLocalStorage<std::unique_ptr<DialogDbSyncInterface>> lsls_db_;
+  };
+  return std::make_shared<DialogDbSyncSafe>(std::move(sqlite_connection));
+}
+
+class DialogDbAsync : public DialogDbAsyncInterface {
+ public:
+  DialogDbAsync(std::shared_ptr<DialogDbSyncSafeInterface> sync_db, int32 scheduler_id) {
+    impl_ = create_actor_on_scheduler<Impl>("DialogDbActor", scheduler_id, std::move(sync_db));
+  }
+
+  void add_dialog(DialogId dialog_id, int64 order, BufferSlice data, Promise<> promise) override {
+    send_closure_later(impl_, &Impl::add_dialog, dialog_id, order, std::move(data), std::move(promise));
+  }
+  void get_dialog(DialogId dialog_id, Promise<BufferSlice> promise) override {
+    send_closure_later(impl_, &Impl::get_dialog, dialog_id, std::move(promise));
+  }
+  void get_dialogs(int64 order, DialogId dialog_id, int32 limit, Promise<std::vector<BufferSlice>> promise) override {
+    send_closure_later(impl_, &Impl::get_dialogs, order, dialog_id, limit, std::move(promise));
+  }
+  void close(Promise<> promise) override {
+    send_closure_later(impl_, &Impl::close, std::move(promise));
+  }
+
+ private:
+  class Impl : public Actor {
+   public:
+    explicit Impl(std::shared_ptr<DialogDbSyncSafeInterface> sync_db_safe) : sync_db_safe_(std::move(sync_db_safe)) {
+    }
+    void add_dialog(DialogId dialog_id, int64 order, BufferSlice data, Promise<> promise) {
+      add_write_query([=, promise = std::move(promise), data = std::move(data)](Unit) mutable {
+        promise.set_result(sync_db_->add_dialog(dialog_id, order, std::move(data)));
+      });
+    }
+    void get_dialog(DialogId dialog_id, Promise<BufferSlice> promise) {
+      add_read_query();
+      promise.set_result(sync_db_->get_dialog(dialog_id));
+    }
+    void get_dialogs(int64 order, DialogId dialog_id, int32 limit, Promise<std::vector<BufferSlice>> promise) {
+      add_read_query();
+      promise.set_result(sync_db_->get_dialogs(order, dialog_id, limit));
+    }
+    void close(Promise<> promise) {
+      do_flush();
+      sync_db_safe_.reset();
+      sync_db_ = nullptr;
+      promise.set_result(Unit());
+      stop();
+    }
+
+   private:
+    std::shared_ptr<DialogDbSyncSafeInterface> sync_db_safe_;
+    DialogDbSyncInterface *sync_db_ = nullptr;
+
+    static constexpr size_t MAX_PENDING_QUERIES_COUNT{50};
+    static constexpr double MAX_PENDING_QUERIES_DELAY{1};
+    std::vector<Promise<>> pending_writes_;
+    double wakeup_at_ = 0;
+    template <class F>
+    void add_write_query(F &&f) {
+      pending_writes_.push_back(PromiseCreator::lambda(std::forward<F>(f), PromiseCreator::Ignore()));
+      if (pending_writes_.size() > MAX_PENDING_QUERIES_COUNT) {
+        do_flush();
+        wakeup_at_ = 0;
+      } else if (wakeup_at_ == 0) {
+        wakeup_at_ = Time::now_cached() + MAX_PENDING_QUERIES_DELAY;
+      }
+      if (wakeup_at_ != 0) {
+        set_timeout_at(wakeup_at_);
+      }
+    }
+    void add_read_query() {
+      do_flush();
+    }
+    void do_flush() {
+      if (pending_writes_.empty()) {
+        return;
+      }
+      sync_db_->begin_transaction().ensure();
+      for (auto &query : pending_writes_) {
+        query.set_value(Unit());
+      }
+      sync_db_->commit_transaction().ensure();
+      pending_writes_.clear();
+      cancel_timeout();
+    }
+    void timeout_expired() override {
+      do_flush();
+    }
+
+    void start_up() override {
+      sync_db_ = &sync_db_safe_->get();
+    }
+  };
+  ActorOwn<Impl> impl_;
+};
+
+std::shared_ptr<DialogDbAsyncInterface> create_dialog_db_async(std::shared_ptr<DialogDbSyncSafeInterface> sync_db,
+                                                               int32 scheduler_id) {
+  return std::make_shared<DialogDbAsync>(std::move(sync_db), scheduler_id);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/DialogDb.h b/libs/tdlib/td/td/telegram/DialogDb.h
new file mode 100644
index 0000000000..f5d51b43a1
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/DialogDb.h
@@ -0,0 +1,68 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/DialogId.h"
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/db/SqliteConnectionSafe.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/Status.h"
+
+#include <memory>
+#include <utility>
+
+namespace td {
+class DialogDbSyncInterface {
+ public:
+  DialogDbSyncInterface() = default;
+  DialogDbSyncInterface(const DialogDbSyncInterface &) = delete;
+  DialogDbSyncInterface &operator=(const DialogDbSyncInterface &) = delete;
+  virtual ~DialogDbSyncInterface() = default;
+
+  virtual Status add_dialog(DialogId dialog_id, int64 order, BufferSlice data) = 0;
+  virtual Result<BufferSlice> get_dialog(DialogId dialog_id) = 0;
+  virtual Result<std::vector<BufferSlice>> get_dialogs(int64 order, DialogId dialog_id, int32 limit) = 0;
+  virtual Status begin_transaction() = 0;
+  virtual Status commit_transaction() = 0;
+};
+
+class DialogDbSyncSafeInterface {
+ public:
+  DialogDbSyncSafeInterface() = default;
+  DialogDbSyncSafeInterface(const DialogDbSyncSafeInterface &) = delete;
+  DialogDbSyncSafeInterface &operator=(const DialogDbSyncSafeInterface &) = delete;
+  virtual ~DialogDbSyncSafeInterface() = default;
+
+  virtual DialogDbSyncInterface &get() = 0;
+};
+
+class DialogDbAsyncInterface {
+ public:
+  DialogDbAsyncInterface() = default;
+  DialogDbAsyncInterface(const DialogDbAsyncInterface &) = delete;
+  DialogDbAsyncInterface &operator=(const DialogDbAsyncInterface &) = delete;
+  virtual ~DialogDbAsyncInterface() = default;
+
+  virtual void add_dialog(DialogId dialog_id, int64 order, BufferSlice data, Promise<> promise) = 0;
+  virtual void get_dialog(DialogId dialog_id, Promise<BufferSlice> promise) = 0;
+  virtual void get_dialogs(int64 order, DialogId dialog_id, int32 limit, Promise<std::vector<BufferSlice>> promise) = 0;
+  virtual void close(Promise<> promise) = 0;
+};
+
+Status init_dialog_db(SqliteDb &db, int version, bool &was_created) TD_WARN_UNUSED_RESULT;
+Status drop_dialog_db(SqliteDb &db, int version) TD_WARN_UNUSED_RESULT;
+
+std::shared_ptr<DialogDbSyncSafeInterface> create_dialog_db_sync(
+    std::shared_ptr<SqliteConnectionSafe> sqlite_connection);
+
+std::shared_ptr<DialogDbAsyncInterface> create_dialog_db_async(std::shared_ptr<DialogDbSyncSafeInterface> sync_db,
+                                                               int32 scheduler_id);
+};  // namespace td
diff --git a/libs/tdlib/td/td/telegram/DialogId.cpp b/libs/tdlib/td/td/telegram/DialogId.cpp
new file mode 100644
index 0000000000..7ea818599c
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/DialogId.cpp
@@ -0,0 +1,153 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/DialogId.h"
+
+#include "td/telegram/telegram_api.h"
+
+#include "td/utils/logging.h"
+
+namespace td {
+
+bool DialogId::is_valid() const {
+  switch (get_type()) {
+    case DialogType::User: {
+      return get_user_id().is_valid();
+    }
+    case DialogType::Chat: {
+      return get_chat_id().is_valid();
+    }
+    case DialogType::Channel: {
+      return get_channel_id().is_valid();
+    }
+    case DialogType::SecretChat: {
+      return get_secret_chat_id().is_valid();
+    }
+    case DialogType::None:
+      return false;
+    default:
+      UNREACHABLE();
+      return false;
+  }
+}
+
+DialogType DialogId::get_type() const {
+  if (id < 0) {
+    if (MIN_CHAT_ID <= id) {
+      return DialogType::Chat;
+    }
+    if (MIN_CHANNEL_ID <= id && id < MAX_CHANNEL_ID) {
+      return DialogType::Channel;
+    }
+    if (MIN_SECRET_ID <= id && id < MAX_SECRET_ID) {
+      return DialogType::SecretChat;
+    }
+  } else if (0 < id && id <= MAX_USER_ID) {
+    return DialogType::User;
+  }
+  return DialogType::None;
+}
+
+UserId DialogId::get_user_id() const {
+  CHECK(get_type() == DialogType::User);
+  return UserId(static_cast<int32>(id));
+}
+
+ChatId DialogId::get_chat_id() const {
+  CHECK(get_type() == DialogType::Chat);
+  return ChatId(static_cast<int32>(-id));
+}
+
+SecretChatId DialogId::get_secret_chat_id() const {
+  CHECK(get_type() == DialogType::SecretChat);
+  return SecretChatId(static_cast<int32>(id - ZERO_SECRET_ID));
+}
+
+ChannelId DialogId::get_channel_id() const {
+  CHECK(get_type() == DialogType::Channel);
+  return ChannelId(static_cast<int32>(MAX_CHANNEL_ID - id));
+}
+
+DialogId::DialogId(UserId user_id) {
+  if (user_id.is_valid()) {
+    id = static_cast<int64>(user_id.get());
+  } else {
+    id = 0;
+  }
+}
+
+DialogId::DialogId(ChatId chat_id) {
+  if (chat_id.is_valid()) {
+    id = -static_cast<int64>(chat_id.get());
+  } else {
+    id = 0;
+  }
+}
+
+DialogId::DialogId(ChannelId channel_id) {
+  if (channel_id.is_valid()) {
+    id = MAX_CHANNEL_ID - static_cast<int64>(channel_id.get());
+  } else {
+    id = 0;
+  }
+}
+
+DialogId::DialogId(SecretChatId chat_id) {
+  if (chat_id.is_valid()) {
+    id = ZERO_SECRET_ID + static_cast<int64>(chat_id.get());
+  } else {
+    id = 0;
+  }
+}
+
+DialogId::DialogId(const tl_object_ptr<telegram_api::dialogPeer> &dialog_peer) {
+  id = get_peer_id(dialog_peer->peer_);
+}
+
+DialogId::DialogId(const tl_object_ptr<telegram_api::Peer> &peer) : id(get_peer_id(peer)) {
+}
+
+int64 DialogId::get_peer_id(const tl_object_ptr<telegram_api::Peer> &peer) {
+  CHECK(peer != nullptr);
+
+  switch (peer->get_id()) {
+    case telegram_api::peerUser::ID: {
+      auto peer_user = static_cast<const telegram_api::peerUser *>(peer.get());
+      UserId user_id(peer_user->user_id_);
+      if (!user_id.is_valid()) {
+        LOG(ERROR) << "Receive invalid " << user_id;
+        return 0;
+      }
+
+      return static_cast<int64>(user_id.get());
+    }
+    case telegram_api::peerChat::ID: {
+      auto peer_chat = static_cast<const telegram_api::peerChat *>(peer.get());
+      ChatId chat_id(peer_chat->chat_id_);
+      if (!chat_id.is_valid()) {
+        LOG(ERROR) << "Receive invalid " << chat_id;
+        return 0;
+      }
+
+      return -static_cast<int64>(chat_id.get());
+    }
+    case telegram_api::peerChannel::ID: {
+      auto peer_channel = static_cast<const telegram_api::peerChannel *>(peer.get());
+      ChannelId channel_id(peer_channel->channel_id_);
+      if (!channel_id.is_valid()) {
+        LOG(ERROR) << "Receive invalid " << channel_id;
+        return 0;
+      }
+
+      return MAX_CHANNEL_ID - static_cast<int64>(channel_id.get());
+    }
+    default:
+      UNREACHABLE();
+      return 0;
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/DialogId.h b/libs/tdlib/td/td/telegram/DialogId.h
new file mode 100644
index 0000000000..ac11ced8a8
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/DialogId.h
@@ -0,0 +1,97 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/ChannelId.h"
+#include "td/telegram/ChatId.h"
+#include "td/telegram/SecretChatId.h"
+#include "td/telegram/UserId.h"
+
+#include "td/utils/common.h"
+#include "td/utils/StringBuilder.h"
+
+#include <functional>
+#include <type_traits>
+
+namespace td {
+
+enum class DialogType { None, User, Chat, Channel, SecretChat };
+
+class DialogId {
+  static constexpr int64 MIN_SECRET_ID = -2002147483648ll;
+  static constexpr int64 ZERO_SECRET_ID = -2000000000000ll;
+  static constexpr int64 MAX_SECRET_ID = -1997852516353ll;
+  static constexpr int64 MIN_CHANNEL_ID = -1002147483647ll;
+  static constexpr int64 MAX_CHANNEL_ID = -1000000000000ll;
+  static constexpr int64 MIN_CHAT_ID = -2147483647ll;
+  static constexpr int64 MAX_USER_ID = 2147483647ll;
+
+  int64 id = 0;
+
+  static int64 get_peer_id(const tl_object_ptr<telegram_api::Peer> &peer);
+
+ public:
+  using UnderlyingType = decltype(id);
+  DialogId() = default;
+
+  explicit DialogId(int64 dialog_id) : id(dialog_id) {
+  }
+  template <class T, typename = std::enable_if_t<std::is_convertible<T, int64>::value>>
+  DialogId(T dialog_id) = delete;
+
+  explicit DialogId(const tl_object_ptr<telegram_api::dialogPeer> &dialog_peer);
+  explicit DialogId(const tl_object_ptr<telegram_api::Peer> &peer);
+  explicit DialogId(UserId user_id);
+  explicit DialogId(ChatId chat_id);
+  explicit DialogId(ChannelId channel_id);
+  explicit DialogId(SecretChatId chat_id);
+
+  int64 get() const {
+    return id;
+  }
+
+  bool operator==(const DialogId &other) const {
+    return id == other.id;
+  }
+
+  bool operator!=(const DialogId &other) const {
+    return id != other.id;
+  }
+
+  bool is_valid() const;
+
+  DialogType get_type() const;
+
+  UserId get_user_id() const;
+  ChatId get_chat_id() const;
+  SecretChatId get_secret_chat_id() const;
+  ChannelId get_channel_id() const;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    storer.store_long(id);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    id = parser.fetch_long();
+  }
+};
+
+struct DialogIdHash {
+  std::size_t operator()(DialogId dialog_id) const {
+    return std::hash<int64>()(dialog_id.get());
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &string_builder, DialogId dialog_id) {
+  return string_builder << "chat " << dialog_id.get();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/DialogParticipant.cpp b/libs/tdlib/td/td/telegram/DialogParticipant.cpp
new file mode 100644
index 0000000000..556d4bde23
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/DialogParticipant.cpp
@@ -0,0 +1,428 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/DialogParticipant.h"
+
+#include "td/telegram/Global.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+
+#include <limits>
+
+namespace td {
+
+int32 DialogParticipantStatus::fix_until_date(int32 date) {
+  if (date == std::numeric_limits<int32>::max() || date < 0) {
+    return 0;
+  }
+  return date;
+}
+
+DialogParticipantStatus DialogParticipantStatus::Creator(bool is_member) {
+  return DialogParticipantStatus(Type::Creator,
+                                 ALL_ADMINISTRATOR_RIGHTS | ALL_RESTRICTED_RIGHTS | (is_member ? IS_MEMBER : 0), 0);
+}
+
+DialogParticipantStatus DialogParticipantStatus::Administrator(bool can_be_edited, bool can_change_info,
+                                                               bool can_post_messages, bool can_edit_messages,
+                                                               bool can_delete_messages, bool can_invite_users,
+                                                               bool can_export_dialog_invite_link,
+                                                               bool can_restrict_members, bool can_pin_messages,
+                                                               bool can_promote_members) {
+  uint32 flags = (static_cast<uint32>(can_be_edited) * CAN_BE_EDITED) |
+                 (static_cast<uint32>(can_change_info) * CAN_CHANGE_INFO_AND_SETTINGS) |
+                 (static_cast<uint32>(can_post_messages) * CAN_POST_MESSAGES) |
+                 (static_cast<uint32>(can_edit_messages) * CAN_EDIT_MESSAGES) |
+                 (static_cast<uint32>(can_delete_messages) * CAN_DELETE_MESSAGES) |
+                 (static_cast<uint32>(can_invite_users) * CAN_INVITE_USERS) |
+                 (static_cast<uint32>(can_export_dialog_invite_link) * CAN_EXPORT_DIALOG_INVITE_LINK) |
+                 (static_cast<uint32>(can_restrict_members) * CAN_RESTRICT_MEMBERS) |
+                 (static_cast<uint32>(can_pin_messages) * CAN_PIN_MESSAGES) |
+                 (static_cast<uint32>(can_promote_members) * CAN_PROMOTE_MEMBERS);
+  if (flags == 0 || flags == CAN_BE_EDITED) {
+    return Member();
+  }
+  return DialogParticipantStatus(Type::Administrator, IS_MEMBER | ALL_RESTRICTED_RIGHTS | flags, 0);
+}
+
+DialogParticipantStatus DialogParticipantStatus::Member() {
+  return DialogParticipantStatus(Type::Member, IS_MEMBER | ALL_RESTRICTED_RIGHTS, 0);
+}
+
+DialogParticipantStatus DialogParticipantStatus::Restricted(bool is_member, int32 restricted_until_date,
+                                                            bool can_send_messages, bool can_send_media,
+                                                            bool can_send_stickers, bool can_send_animations,
+                                                            bool can_send_games, bool can_use_inline_bots,
+                                                            bool can_add_web_page_previews) {
+  uint32 flags = (static_cast<uint32>(can_send_messages) * CAN_SEND_MESSAGES) |
+                 (static_cast<uint32>(can_send_media) * CAN_SEND_MEDIA) |
+                 (static_cast<uint32>(can_send_stickers) * CAN_SEND_STICKERS) |
+                 (static_cast<uint32>(can_send_animations) * CAN_SEND_ANIMATIONS) |
+                 (static_cast<uint32>(can_send_games) * CAN_SEND_GAMES) |
+                 (static_cast<uint32>(can_use_inline_bots) * CAN_USE_INLINE_BOTS) |
+                 (static_cast<uint32>(can_add_web_page_previews) * CAN_ADD_WEB_PAGE_PREVIEWS) |
+                 (static_cast<uint32>(is_member) * IS_MEMBER);
+  if (flags == (IS_MEMBER | ALL_RESTRICTED_RIGHTS)) {
+    return Member();
+  }
+  return DialogParticipantStatus(Type::Restricted, flags, fix_until_date(restricted_until_date));
+}
+
+DialogParticipantStatus DialogParticipantStatus::Left() {
+  return DialogParticipantStatus(Type::Left, ALL_RESTRICTED_RIGHTS, 0);
+}
+
+DialogParticipantStatus DialogParticipantStatus::Banned(int32 banned_until_date) {
+  return DialogParticipantStatus(Type::Banned, 0, fix_until_date(banned_until_date));
+}
+
+DialogParticipantStatus DialogParticipantStatus::GroupAdministrator(bool is_creator) {
+  return DialogParticipantStatus::Administrator(is_creator, true, false, false, true, true, false, true, false, false);
+}
+
+DialogParticipantStatus DialogParticipantStatus::ChannelAdministrator(bool is_creator, bool is_megagroup) {
+  if (is_megagroup) {
+    return DialogParticipantStatus::Administrator(is_creator, true, false, false, true, true, false, true, true, false);
+  } else {
+    return DialogParticipantStatus::Administrator(is_creator, false, true, true, true, false, false, true, false,
+                                                  false);
+  }
+}
+
+tl_object_ptr<td_api::ChatMemberStatus> DialogParticipantStatus::get_chat_member_status_object() const {
+  switch (type_) {
+    case Type::Creator:
+      return make_tl_object<td_api::chatMemberStatusCreator>(is_member());
+    case Type::Administrator:
+      return make_tl_object<td_api::chatMemberStatusAdministrator>(
+          can_be_edited(), can_change_info_and_settings(), can_post_messages(), can_edit_messages(),
+          can_delete_messages(), can_invite_users() || can_export_dialog_invite_link(), can_restrict_members(),
+          can_pin_messages(), can_promote_members());
+    case Type::Member:
+      return make_tl_object<td_api::chatMemberStatusMember>();
+    case Type::Restricted:
+      return make_tl_object<td_api::chatMemberStatusRestricted>(
+          is_member(), until_date_, can_send_messages(), can_send_media(),
+          can_send_stickers() && can_send_animations() && can_send_games() && can_use_inline_bots(),
+          can_add_web_page_previews());
+    case Type::Left:
+      return make_tl_object<td_api::chatMemberStatusLeft>();
+    case Type::Banned:
+      return make_tl_object<td_api::chatMemberStatusBanned>(until_date_);
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+tl_object_ptr<telegram_api::channelAdminRights> DialogParticipantStatus::get_channel_admin_rights() const {
+  int32 flags = 0;
+  if (can_change_info_and_settings()) {
+    flags |= telegram_api::channelAdminRights::CHANGE_INFO_MASK;
+  }
+  if (can_post_messages()) {
+    flags |= telegram_api::channelAdminRights::POST_MESSAGES_MASK;
+  }
+  if (can_edit_messages()) {
+    flags |= telegram_api::channelAdminRights::EDIT_MESSAGES_MASK;
+  }
+  if (can_delete_messages()) {
+    flags |= telegram_api::channelAdminRights::DELETE_MESSAGES_MASK;
+  }
+  if (can_invite_users()) {
+    flags |= telegram_api::channelAdminRights::INVITE_USERS_MASK;
+  }
+  if (can_export_dialog_invite_link()) {
+    flags |= telegram_api::channelAdminRights::INVITE_LINK_MASK;
+  }
+  if (can_restrict_members()) {
+    flags |= telegram_api::channelAdminRights::BAN_USERS_MASK;
+  }
+  if (can_pin_messages()) {
+    flags |= telegram_api::channelAdminRights::PIN_MESSAGES_MASK;
+  }
+  if (can_promote_members()) {
+    flags |= telegram_api::channelAdminRights::ADD_ADMINS_MASK;
+  }
+
+  LOG(INFO) << "Create channel admin rights " << flags;
+  return make_tl_object<telegram_api::channelAdminRights>(
+      flags, false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/,
+      false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/);
+}
+
+tl_object_ptr<telegram_api::channelBannedRights> DialogParticipantStatus::get_channel_banned_rights() const {
+  int32 flags = 0;
+  if (type_ == Type::Banned) {
+    flags |= telegram_api::channelBannedRights::VIEW_MESSAGES_MASK;
+  }
+  if (!can_send_messages()) {
+    flags |= telegram_api::channelBannedRights::SEND_MESSAGES_MASK;
+  }
+  if (!can_send_media()) {
+    flags |= telegram_api::channelBannedRights::SEND_MEDIA_MASK;
+  }
+  if (!can_send_stickers()) {
+    flags |= telegram_api::channelBannedRights::SEND_STICKERS_MASK;
+  }
+  if (!can_send_animations()) {
+    flags |= telegram_api::channelBannedRights::SEND_GIFS_MASK;
+  }
+  if (!can_send_games()) {
+    flags |= telegram_api::channelBannedRights::SEND_GAMES_MASK;
+  }
+  if (!can_use_inline_bots()) {
+    flags |= telegram_api::channelBannedRights::SEND_INLINE_MASK;
+  }
+  if (!can_add_web_page_previews()) {
+    flags |= telegram_api::channelBannedRights::EMBED_LINKS_MASK;
+  }
+
+  LOG(INFO) << "Create channel banned rights " << flags << " until " << until_date_;
+  return make_tl_object<telegram_api::channelBannedRights>(
+      flags, false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/,
+      false /*ignored*/, false /*ignored*/, false /*ignored*/, until_date_);
+}
+
+void DialogParticipantStatus::update_restrictions() const {
+  if (until_date_ != 0 && G()->unix_time() > until_date_) {
+    until_date_ = 0;
+    if (type_ == Type::Restricted) {
+      if (is_member()) {
+        type_ = Type::Member;
+      } else {
+        type_ = Type::Left;
+      }
+      flags_ |= ALL_RESTRICTED_RIGHTS;
+    } else if (type_ == Type::Banned) {
+      type_ = Type::Left;
+    } else {
+      UNREACHABLE();
+    }
+  }
+}
+
+bool operator==(const DialogParticipantStatus &lhs, const DialogParticipantStatus &rhs) {
+  return lhs.type_ == rhs.type_ && lhs.flags_ == rhs.flags_ && lhs.until_date_ == rhs.until_date_;
+}
+
+bool operator!=(const DialogParticipantStatus &lhs, const DialogParticipantStatus &rhs) {
+  return !(lhs == rhs);
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const DialogParticipantStatus &status) {
+  switch (status.type_) {
+    case DialogParticipantStatus::Type::Creator:
+      string_builder << "Creator";
+      if (!status.is_member()) {
+        string_builder << "-non-member";
+      }
+      return string_builder;
+    case DialogParticipantStatus::Type::Administrator:
+      string_builder << "Administrator: ";
+      if (status.can_change_info_and_settings()) {
+        string_builder << "(change)";
+      }
+      if (status.can_post_messages()) {
+        string_builder << "(post)";
+      }
+      if (status.can_edit_messages()) {
+        string_builder << "(edit)";
+      }
+      if (status.can_delete_messages()) {
+        string_builder << "(delete)";
+      }
+      if (status.can_invite_users()) {
+        string_builder << "(invite)";
+      }
+      if (status.can_restrict_members()) {
+        string_builder << "(restrict)";
+      }
+      if (status.can_pin_messages()) {
+        string_builder << "(pin)";
+      }
+      if (status.can_promote_members()) {
+        string_builder << "(promote)";
+      }
+      return string_builder;
+    case DialogParticipantStatus::Type::Member:
+      return string_builder << "Member";
+    case DialogParticipantStatus::Type::Restricted:
+      string_builder << "Restricted ";
+      if (status.until_date_ == 0) {
+        string_builder << "forever ";
+      } else {
+        string_builder << "until " << status.until_date_ << " ";
+      }
+      if (!status.is_member()) {
+        string_builder << "non-";
+      }
+      string_builder << "member: ";
+      if (!status.can_send_messages()) {
+        string_builder << "(text)";
+      }
+      if (!status.can_send_media()) {
+        string_builder << "(media)";
+      }
+      if (!status.can_send_stickers()) {
+        string_builder << "(stickers)";
+      }
+      if (!status.can_send_animations()) {
+        string_builder << "(animations)";
+      }
+      if (!status.can_send_games()) {
+        string_builder << "(games)";
+      }
+      if (!status.can_use_inline_bots()) {
+        string_builder << "(inline bots)";
+      }
+      if (!status.can_add_web_page_previews()) {
+        string_builder << "(links)";
+      }
+      return string_builder;
+    case DialogParticipantStatus::Type::Left:
+      return string_builder << "Left";
+    case DialogParticipantStatus::Type::Banned:
+      string_builder << "Banned ";
+      if (status.until_date_ == 0) {
+        string_builder << "forever";
+      } else {
+        string_builder << "until " << status.until_date_;
+      }
+      return string_builder;
+    default:
+      UNREACHABLE();
+      return string_builder << "Impossible";
+  }
+}
+
+DialogParticipantStatus get_dialog_participant_status(const tl_object_ptr<td_api::ChatMemberStatus> &status) {
+  auto constructor_id = status == nullptr ? td_api::chatMemberStatusMember::ID : status->get_id();
+  switch (constructor_id) {
+    case td_api::chatMemberStatusCreator::ID: {
+      auto st = static_cast<const td_api::chatMemberStatusCreator *>(status.get());
+      return DialogParticipantStatus::Creator(st->is_member_);
+    }
+    case td_api::chatMemberStatusAdministrator::ID: {
+      auto st = static_cast<const td_api::chatMemberStatusAdministrator *>(status.get());
+      return DialogParticipantStatus::Administrator(
+          st->can_be_edited_, st->can_change_info_, st->can_post_messages_, st->can_edit_messages_,
+          st->can_delete_messages_, st->can_invite_users_, st->can_invite_users_, st->can_restrict_members_,
+          st->can_pin_messages_, st->can_promote_members_);
+    }
+    case td_api::chatMemberStatusMember::ID:
+      return DialogParticipantStatus::Member();
+    case td_api::chatMemberStatusRestricted::ID: {
+      auto st = static_cast<const td_api::chatMemberStatusRestricted *>(status.get());
+      bool can_send_media =
+          st->can_send_media_messages_ || st->can_send_other_messages_ || st->can_add_web_page_previews_;
+      return DialogParticipantStatus::Restricted(
+          st->is_member_, st->restricted_until_date_, st->can_send_messages_ || can_send_media, can_send_media,
+          st->can_send_other_messages_, st->can_send_other_messages_, st->can_send_other_messages_,
+          st->can_send_other_messages_, st->can_add_web_page_previews_);
+    }
+    case td_api::chatMemberStatusLeft::ID:
+      return DialogParticipantStatus::Left();
+    case td_api::chatMemberStatusBanned::ID: {
+      auto st = static_cast<const td_api::chatMemberStatusBanned *>(status.get());
+      return DialogParticipantStatus::Banned(st->banned_until_date_);
+    }
+    default:
+      UNREACHABLE();
+      return DialogParticipantStatus::Member();
+  }
+}
+
+DialogParticipantStatus get_dialog_participant_status(
+    bool can_be_edited, const tl_object_ptr<telegram_api::channelAdminRights> &admin_rights) {
+  bool can_change_info = (admin_rights->flags_ & telegram_api::channelAdminRights::CHANGE_INFO_MASK) != 0;
+  bool can_post_messages = (admin_rights->flags_ & telegram_api::channelAdminRights::POST_MESSAGES_MASK) != 0;
+  bool can_edit_messages = (admin_rights->flags_ & telegram_api::channelAdminRights::EDIT_MESSAGES_MASK) != 0;
+  bool can_delete_messages = (admin_rights->flags_ & telegram_api::channelAdminRights::DELETE_MESSAGES_MASK) != 0;
+  bool can_invite_users = (admin_rights->flags_ & telegram_api::channelAdminRights::INVITE_USERS_MASK) != 0;
+  bool can_export_invite_link = (admin_rights->flags_ & telegram_api::channelAdminRights::INVITE_LINK_MASK) != 0;
+  bool can_restrict_members = (admin_rights->flags_ & telegram_api::channelAdminRights::BAN_USERS_MASK) != 0;
+  bool can_pin_messages = (admin_rights->flags_ & telegram_api::channelAdminRights::PIN_MESSAGES_MASK) != 0;
+  bool can_promote_members = (admin_rights->flags_ & telegram_api::channelAdminRights::ADD_ADMINS_MASK) != 0;
+  return DialogParticipantStatus::Administrator(can_be_edited, can_change_info, can_post_messages, can_edit_messages,
+                                                can_delete_messages, can_invite_users, can_export_invite_link,
+                                                can_restrict_members, can_pin_messages, can_promote_members);
+}
+
+DialogParticipantStatus get_dialog_participant_status(
+    bool is_member, const tl_object_ptr<telegram_api::channelBannedRights> &banned_rights) {
+  bool can_view_messages = (banned_rights->flags_ & telegram_api::channelBannedRights::VIEW_MESSAGES_MASK) == 0;
+  if (!can_view_messages) {
+    return DialogParticipantStatus::Banned(banned_rights->until_date_);
+  }
+  bool can_send_messages = (banned_rights->flags_ & telegram_api::channelBannedRights::SEND_MESSAGES_MASK) == 0;
+  bool can_send_media_messages = (banned_rights->flags_ & telegram_api::channelBannedRights::SEND_MEDIA_MASK) == 0;
+  bool can_send_stickers = (banned_rights->flags_ & telegram_api::channelBannedRights::SEND_STICKERS_MASK) == 0;
+  bool can_send_animations = (banned_rights->flags_ & telegram_api::channelBannedRights::SEND_GIFS_MASK) == 0;
+  bool can_send_games = (banned_rights->flags_ & telegram_api::channelBannedRights::SEND_GAMES_MASK) == 0;
+  bool can_use_inline_bots = (banned_rights->flags_ & telegram_api::channelBannedRights::SEND_INLINE_MASK) == 0;
+  bool can_add_web_page_previews = (banned_rights->flags_ & telegram_api::channelBannedRights::EMBED_LINKS_MASK) == 0;
+  return DialogParticipantStatus::Restricted(is_member, banned_rights->until_date_, can_send_messages,
+                                             can_send_media_messages, can_send_stickers, can_send_animations,
+                                             can_send_games, can_use_inline_bots, can_add_web_page_previews);
+}
+
+tl_object_ptr<telegram_api::ChannelParticipantsFilter>
+ChannelParticipantsFilter::get_input_channel_participants_filter() const {
+  switch (type) {
+    case Recent:
+      return make_tl_object<telegram_api::channelParticipantsRecent>();
+    case Administrators:
+      return make_tl_object<telegram_api::channelParticipantsAdmins>();
+    case Search:
+      return make_tl_object<telegram_api::channelParticipantsSearch>(query);
+    case Restricted:
+      return make_tl_object<telegram_api::channelParticipantsBanned>(query);
+    case Banned:
+      return make_tl_object<telegram_api::channelParticipantsKicked>(query);
+    case Bots:
+      return make_tl_object<telegram_api::channelParticipantsBots>();
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+ChannelParticipantsFilter::ChannelParticipantsFilter(const tl_object_ptr<td_api::SupergroupMembersFilter> &filter) {
+  if (filter == nullptr) {
+    type = Recent;
+    return;
+  }
+  switch (filter->get_id()) {
+    case td_api::supergroupMembersFilterRecent::ID:
+      type = Recent;
+      return;
+    case td_api::supergroupMembersFilterAdministrators::ID:
+      type = Administrators;
+      return;
+    case td_api::supergroupMembersFilterSearch::ID:
+      type = Search;
+      query = static_cast<const td_api::supergroupMembersFilterSearch *>(filter.get())->query_;
+      return;
+    case td_api::supergroupMembersFilterRestricted::ID:
+      type = Restricted;
+      query = static_cast<const td_api::supergroupMembersFilterRestricted *>(filter.get())->query_;
+      return;
+    case td_api::supergroupMembersFilterBanned::ID:
+      type = Banned;
+      query = static_cast<const td_api::supergroupMembersFilterBanned *>(filter.get())->query_;
+      return;
+    case td_api::supergroupMembersFilterBots::ID:
+      type = Bots;
+      return;
+    default:
+      UNREACHABLE();
+      type = Recent;
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/DialogParticipant.h b/libs/tdlib/td/td/telegram/DialogParticipant.h
new file mode 100644
index 0000000000..ab4c36a320
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/DialogParticipant.h
@@ -0,0 +1,263 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/UserId.h"
+
+#include "td/utils/common.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+
+class DialogParticipantStatus {
+  static constexpr uint32 CAN_CHANGE_INFO_AND_SETTINGS = 1 << 0;
+  static constexpr uint32 CAN_POST_MESSAGES = 1 << 1;
+  static constexpr uint32 CAN_EDIT_MESSAGES = 1 << 2;
+  static constexpr uint32 CAN_DELETE_MESSAGES = 1 << 3;
+  static constexpr uint32 CAN_INVITE_USERS = 1 << 4;
+  static constexpr uint32 CAN_EXPORT_DIALOG_INVITE_LINK = 1 << 5;
+  static constexpr uint32 CAN_RESTRICT_MEMBERS = 1 << 6;
+  static constexpr uint32 CAN_PIN_MESSAGES = 1 << 7;
+  static constexpr uint32 CAN_PROMOTE_MEMBERS = 1 << 8;
+
+  static constexpr uint32 CAN_BE_EDITED = 1 << 15;
+
+  static constexpr uint32 CAN_SEND_MESSAGES = 1 << 16;
+  static constexpr uint32 CAN_SEND_MEDIA = 1 << 17;
+  static constexpr uint32 CAN_SEND_STICKERS = 1 << 18;
+  static constexpr uint32 CAN_SEND_ANIMATIONS = 1 << 19;
+  static constexpr uint32 CAN_SEND_GAMES = 1 << 20;
+  static constexpr uint32 CAN_USE_INLINE_BOTS = 1 << 21;
+  static constexpr uint32 CAN_ADD_WEB_PAGE_PREVIEWS = 1 << 22;
+
+  static constexpr uint32 IS_MEMBER = 1 << 27;
+
+  // bits 28-31 reserved for Type and until_date flag
+  static constexpr int TYPE_SHIFT = 28;
+  static constexpr uint32 HAS_UNTIL_DATE = 1u << 31;
+
+  static constexpr uint32 ALL_ADMINISTRATOR_RIGHTS =
+      CAN_CHANGE_INFO_AND_SETTINGS | CAN_POST_MESSAGES | CAN_EDIT_MESSAGES | CAN_DELETE_MESSAGES | CAN_INVITE_USERS |
+      CAN_EXPORT_DIALOG_INVITE_LINK | CAN_RESTRICT_MEMBERS | CAN_PIN_MESSAGES | CAN_PROMOTE_MEMBERS;
+
+  static constexpr uint32 ALL_RESTRICTED_RIGHTS = CAN_SEND_MESSAGES | CAN_SEND_MEDIA | CAN_SEND_STICKERS |
+                                                  CAN_SEND_ANIMATIONS | CAN_SEND_GAMES | CAN_USE_INLINE_BOTS |
+                                                  CAN_ADD_WEB_PAGE_PREVIEWS;
+
+  enum class Type { Creator, Administrator, Member, Restricted, Left, Banned };
+  // all fields are logically const, but should be updated in update_restrictions()
+  mutable Type type_;
+  mutable uint32 flags_;
+  mutable int32 until_date_;  // restricted and banned only
+
+  static int32 fix_until_date(int32 date);
+
+  DialogParticipantStatus(Type type, uint32 flags, int32 until_date)
+      : type_(type), flags_(flags), until_date_(until_date) {
+  }
+
+ public:
+  static DialogParticipantStatus Creator(bool is_member);
+
+  static DialogParticipantStatus Administrator(bool can_be_edited, bool can_change_info, bool can_post_messages,
+                                               bool can_edit_messages, bool can_delete_messages, bool can_invite_users,
+                                               bool can_export_dialog_invite_link, bool can_restrict_members,
+                                               bool can_pin_messages, bool can_promote_members);
+
+  static DialogParticipantStatus Member();
+
+  static DialogParticipantStatus Restricted(bool is_member, int32 restricted_until_date, bool can_send_messages,
+                                            bool can_send_media, bool can_send_stickers, bool can_send_animations,
+                                            bool can_send_games, bool can_use_inline_bots,
+                                            bool can_add_web_page_previews);
+
+  static DialogParticipantStatus Left();
+
+  static DialogParticipantStatus Banned(int32 banned_until_date);
+
+  // legacy rights
+  static DialogParticipantStatus GroupAdministrator(bool is_creator);
+
+  // legacy rights
+  static DialogParticipantStatus ChannelAdministrator(bool is_creator, bool is_megagroup);
+
+  tl_object_ptr<td_api::ChatMemberStatus> get_chat_member_status_object() const;
+
+  tl_object_ptr<telegram_api::channelAdminRights> get_channel_admin_rights() const;
+
+  tl_object_ptr<telegram_api::channelBannedRights> get_channel_banned_rights() const;
+
+  // unrestricts user if restriction time expired. Should be called before all privileges checks
+  void update_restrictions() const;
+
+  bool can_change_info_and_settings() const {
+    return (flags_ & CAN_CHANGE_INFO_AND_SETTINGS) != 0;
+  }
+
+  bool can_post_messages() const {
+    return (flags_ & CAN_POST_MESSAGES) != 0;
+  }
+
+  bool can_edit_messages() const {
+    return (flags_ & CAN_EDIT_MESSAGES) != 0;
+  }
+
+  bool can_delete_messages() const {
+    return (flags_ & CAN_DELETE_MESSAGES) != 0;
+  }
+
+  bool can_invite_users() const {
+    return (flags_ & CAN_INVITE_USERS) != 0;
+  }
+
+  bool can_export_dialog_invite_link() const {
+    return (flags_ & CAN_EXPORT_DIALOG_INVITE_LINK) != 0;
+  }
+
+  bool can_restrict_members() const {
+    return (flags_ & CAN_RESTRICT_MEMBERS) != 0;
+  }
+
+  bool can_pin_messages() const {
+    return (flags_ & CAN_PIN_MESSAGES) != 0;
+  }
+
+  bool can_promote_members() const {
+    return (flags_ & CAN_PROMOTE_MEMBERS) != 0;
+  }
+
+  bool can_be_edited() const {
+    return (flags_ & CAN_BE_EDITED) != 0;
+  }
+
+  bool can_send_messages() const {
+    return (flags_ & CAN_SEND_MESSAGES) != 0;
+  }
+
+  bool can_send_media() const {
+    return (flags_ & CAN_SEND_MEDIA) != 0;
+  }
+
+  bool can_send_stickers() const {
+    return (flags_ & CAN_SEND_STICKERS) != 0;
+  }
+
+  bool can_send_animations() const {
+    return (flags_ & CAN_SEND_ANIMATIONS) != 0;
+  }
+
+  bool can_send_games() const {
+    return (flags_ & CAN_SEND_GAMES) != 0;
+  }
+
+  bool can_use_inline_bots() const {
+    return (flags_ & CAN_USE_INLINE_BOTS) != 0;
+  }
+
+  bool can_add_web_page_previews() const {
+    return (flags_ & CAN_ADD_WEB_PAGE_PREVIEWS) != 0;
+  }
+
+  bool is_member() const {
+    return (flags_ & IS_MEMBER) != 0;
+  }
+
+  bool is_creator() const {
+    return type_ == Type::Creator;
+  }
+
+  bool is_administrator() const {
+    return type_ == Type::Administrator || type_ == Type::Creator;
+  }
+
+  bool is_restricted() const {
+    return type_ == Type::Restricted;
+  }
+
+  bool is_banned() const {
+    return type_ == Type::Banned;
+  }
+
+  int32 get_until_date() const {
+    return until_date_;
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    uint32 stored_flags = flags_ | (static_cast<uint32>(type_) << TYPE_SHIFT);
+    if (until_date_ > 0) {
+      stored_flags |= HAS_UNTIL_DATE;
+    }
+    td::store(stored_flags, storer);
+    if (until_date_ > 0) {
+      td::store(until_date_, storer);
+    }
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    uint32 stored_flags;
+    td::parse(stored_flags, parser);
+    if ((stored_flags & HAS_UNTIL_DATE) != 0) {
+      td::parse(until_date_, parser);
+      stored_flags &= ~HAS_UNTIL_DATE;
+    }
+    type_ = static_cast<Type>(stored_flags >> TYPE_SHIFT);
+    flags_ = stored_flags & ((1 << TYPE_SHIFT) - 1);
+  }
+
+  friend bool operator==(const DialogParticipantStatus &lhs, const DialogParticipantStatus &rhs);
+
+  friend StringBuilder &operator<<(StringBuilder &string_builder, const DialogParticipantStatus &status);
+};
+
+bool operator==(const DialogParticipantStatus &lhs, const DialogParticipantStatus &rhs);
+
+bool operator!=(const DialogParticipantStatus &lhs, const DialogParticipantStatus &rhs);
+
+StringBuilder &operator<<(StringBuilder &string_builder, const DialogParticipantStatus &status);
+
+struct DialogParticipant {
+  UserId user_id;
+  UserId inviter_user_id;
+  int32 joined_date = 0;
+  DialogParticipantStatus status = DialogParticipantStatus::Left();
+
+  DialogParticipant() = default;
+
+  DialogParticipant(UserId user_id, UserId inviter_user_id, int32 joined_date, DialogParticipantStatus status)
+      : user_id(user_id), inviter_user_id(inviter_user_id), joined_date(joined_date), status(status) {
+  }
+};
+
+class ChannelParticipantsFilter {
+  enum { Recent, Administrators, Search, Restricted, Banned, Bots } type;
+  string query;
+
+ public:
+  explicit ChannelParticipantsFilter(const tl_object_ptr<td_api::SupergroupMembersFilter> &filter);
+
+  tl_object_ptr<telegram_api::ChannelParticipantsFilter> get_input_channel_participants_filter() const;
+
+  bool is_administrators() const {
+    return type == Administrators;
+  }
+};
+
+DialogParticipantStatus get_dialog_participant_status(const tl_object_ptr<td_api::ChatMemberStatus> &status);
+
+DialogParticipantStatus get_dialog_participant_status(
+    bool can_be_edited, const tl_object_ptr<telegram_api::channelAdminRights> &admin_rights);
+
+DialogParticipantStatus get_dialog_participant_status(
+    bool is_member, const tl_object_ptr<telegram_api::channelBannedRights> &banned_rights);
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/DocumentsManager.cpp b/libs/tdlib/td/td/telegram/DocumentsManager.cpp
new file mode 100644
index 0000000000..f39ade91c2
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/DocumentsManager.cpp
@@ -0,0 +1,578 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/DocumentsManager.h"
+
+#include "td/telegram/AnimationsManager.h"
+#include "td/telegram/AudiosManager.h"
+#include "td/telegram/files/FileManager.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/StickersManager.h"
+#include "td/telegram/Td.h"
+#include "td/telegram/VideoNotesManager.h"
+#include "td/telegram/VideosManager.h"
+#include "td/telegram/VoiceNotesManager.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/HttpUrl.h"
+#include "td/utils/logging.h"
+#include "td/utils/MimeType.h"
+#include "td/utils/misc.h"
+#include "td/utils/PathView.h"
+#include "td/utils/Random.h"
+#include "td/utils/Slice.h"
+#include "td/utils/StackAllocator.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/utf8.h"
+
+#include <limits>
+
+namespace td {
+
+DocumentsManager::DocumentsManager(Td *td) : td_(td) {
+}
+
+tl_object_ptr<td_api::document> DocumentsManager::get_document_object(FileId file_id) {
+  if (!file_id.is_valid()) {
+    return nullptr;
+  }
+
+  LOG(INFO) << "Return document " << file_id << " object";
+  auto &document = documents_[file_id];
+  CHECK(document != nullptr) << tag("file_id", file_id);
+  document->is_changed = false;
+  return make_tl_object<td_api::document>(document->file_name, document->mime_type,
+                                          get_photo_size_object(td_->file_manager_.get(), &document->thumbnail),
+                                          td_->file_manager_->get_file_object(file_id));
+}
+
+std::pair<DocumentsManager::DocumentType, FileId> DocumentsManager::on_get_document(
+    RemoteDocument remote_document, DialogId owner_dialog_id, MultiPromiseActor *load_data_multipromise_ptr,
+    DocumentType default_document_type) {
+  tl_object_ptr<telegram_api::documentAttributeAnimated> animated;
+  tl_object_ptr<telegram_api::documentAttributeVideo> video;
+  tl_object_ptr<telegram_api::documentAttributeAudio> audio;
+  tl_object_ptr<telegram_api::documentAttributeSticker> sticker;
+  Dimensions dimensions;
+  string file_name;
+  bool has_stickers = false;
+  int32 type_attributes = 0;
+  for (auto &attribute : remote_document.attributes) {
+    switch (attribute->get_id()) {
+      case telegram_api::documentAttributeImageSize::ID: {
+        auto image_size = move_tl_object_as<telegram_api::documentAttributeImageSize>(attribute);
+        dimensions = get_dimensions(image_size->w_, image_size->h_);
+        break;
+      }
+      case telegram_api::documentAttributeAnimated::ID:
+        animated = move_tl_object_as<telegram_api::documentAttributeAnimated>(attribute);
+        type_attributes++;
+        break;
+      case telegram_api::documentAttributeSticker::ID:
+        sticker = move_tl_object_as<telegram_api::documentAttributeSticker>(attribute);
+        type_attributes++;
+        break;
+      case telegram_api::documentAttributeVideo::ID:
+        video = move_tl_object_as<telegram_api::documentAttributeVideo>(attribute);
+        type_attributes++;
+        break;
+      case telegram_api::documentAttributeAudio::ID:
+        audio = move_tl_object_as<telegram_api::documentAttributeAudio>(attribute);
+        type_attributes++;
+        break;
+      case telegram_api::documentAttributeFilename::ID:
+        file_name = std::move(static_cast<telegram_api::documentAttributeFilename *>(attribute.get())->file_name_);
+        break;
+      case telegram_api::documentAttributeHasStickers::ID:
+        has_stickers = true;
+        break;
+      default:
+        UNREACHABLE();
+    }
+  }
+  int32 video_duration = 0;
+  if (video != nullptr) {
+    video_duration = video->duration_;
+    if (dimensions.width == 0) {
+      dimensions = get_dimensions(video->w_, video->h_);
+    }
+
+    if (animated != nullptr) {
+      // video animation
+      type_attributes--;
+      video = nullptr;
+    }
+  }
+  if (animated != nullptr && audio != nullptr) {
+    // animation send as audio
+    type_attributes--;
+    audio = nullptr;
+  }
+  if (animated != nullptr && sticker != nullptr) {
+    // animation send as sticker
+    type_attributes--;
+    sticker = nullptr;
+  }
+
+  auto document_type = default_document_type;
+  FileType file_type = FileType::Document;
+  Slice default_extension;
+  bool supports_streaming = false;
+  if (type_attributes == 1 || default_document_type != DocumentType::General) {  // not a general document
+    if (animated != nullptr || default_document_type == DocumentType::Animation) {
+      document_type = DocumentType::Animation;
+      file_type = FileType::Animation;
+      default_extension = "mp4";
+    } else if (audio != nullptr || default_document_type == DocumentType::Audio ||
+               default_document_type == DocumentType::VoiceNote) {
+      bool is_voice_note = default_document_type == DocumentType::VoiceNote;
+      if (audio != nullptr) {
+        is_voice_note = (audio->flags_ & telegram_api::documentAttributeAudio::Flags::VOICE_MASK) != 0;
+      }
+      if (is_voice_note) {
+        document_type = DocumentType::VoiceNote;
+        file_type = FileType::VoiceNote;
+        default_extension = "oga";
+        file_name.clear();
+      } else {
+        document_type = DocumentType::Audio;
+        file_type = FileType::Audio;
+        default_extension = "mp3";
+      }
+    } else if (sticker != nullptr || default_document_type == DocumentType::Sticker) {
+      document_type = DocumentType::Sticker;
+      file_type = FileType::Sticker;
+      default_extension = "webp";
+      owner_dialog_id = DialogId();
+      file_name.clear();
+    } else if (video != nullptr || default_document_type == DocumentType::Video ||
+               default_document_type == DocumentType::VideoNote) {
+      bool is_video_note = default_document_type == DocumentType::VideoNote;
+      if (video != nullptr) {
+        is_video_note = (video->flags_ & telegram_api::documentAttributeVideo::ROUND_MESSAGE_MASK) != 0;
+        if (!is_video_note) {
+          supports_streaming = (video->flags_ & telegram_api::documentAttributeVideo::SUPPORTS_STREAMING_MASK) != 0;
+        }
+      }
+      if (is_video_note) {
+        document_type = DocumentType::VideoNote;
+        file_type = FileType::VideoNote;
+        file_name.clear();
+      } else {
+        document_type = DocumentType::Video;
+        file_type = FileType::Video;
+      }
+      default_extension = "mp4";
+    }
+  } else if (type_attributes >= 2) {
+    LOG(WARNING) << "Receive document with more than 1 type attribute: animated = " << to_string(animated)
+                 << ", sticker = " << to_string(sticker) << ", video = " << to_string(video)
+                 << ", audio = " << to_string(audio) << ", file_name = " << file_name << ", dimensions = " << dimensions
+                 << ", has_stickers = " << has_stickers;
+  }
+
+  int64 id;
+  int64 access_hash;
+  int32 dc_id;
+  int32 size;
+  string mime_type;
+  PhotoSize thumbnail;
+  FileEncryptionKey encryption_key;
+  bool is_web = false;
+  bool is_web_no_proxy = false;
+  string url;
+  if (remote_document.document != nullptr) {
+    auto document = std::move(remote_document.document);
+
+    id = document->id_;
+    access_hash = document->access_hash_;
+    dc_id = document->dc_id_;
+    size = document->size_;
+    mime_type = std::move(document->mime_type_);
+
+    if (document_type != DocumentType::VoiceNote) {
+      thumbnail = get_photo_size(td_->file_manager_.get(), FileType::Thumbnail, 0, 0, owner_dialog_id,
+                                 std::move(document->thumb_));
+    }
+  } else if (remote_document.secret_file != nullptr) {
+    CHECK(remote_document.secret_document != nullptr);
+    auto file = std::move(remote_document.secret_file);
+    auto document = std::move(remote_document.secret_document);
+
+    id = file->id_;
+    access_hash = file->access_hash_;
+    dc_id = file->dc_id_;
+    size = document->size_;
+    mime_type = std::move(document->mime_type_);
+    file_type = FileType::Encrypted;
+    encryption_key = FileEncryptionKey{document->key_.as_slice(), document->iv_.as_slice()};
+    if (encryption_key.empty()) {
+      return {DocumentType::Unknown, FileId()};
+    }
+
+    if (document_type != DocumentType::VoiceNote) {
+      thumbnail = get_thumbnail_photo_size(td_->file_manager_.get(), std::move(document->thumb_), owner_dialog_id,
+                                           document->thumb_w_, document->thumb_h_);
+    }
+  } else {
+    is_web = true;
+    id = Random::fast(0, std::numeric_limits<int32>::max());
+    dc_id = 0;
+    access_hash = 0;
+    thumbnail = std::move(remote_document.thumbnail);
+
+    auto web_document_ptr = std::move(remote_document.web_document);
+    switch (web_document_ptr->get_id()) {
+      case telegram_api::webDocument::ID: {
+        auto web_document = move_tl_object_as<telegram_api::webDocument>(web_document_ptr);
+        auto r_http_url = parse_url(web_document->url_);
+        if (r_http_url.is_error()) {
+          LOG(ERROR) << "Can't parse URL " << web_document->url_;
+          return {DocumentType::Unknown, FileId()};
+        }
+        auto http_url = r_http_url.move_as_ok();
+
+        dc_id = web_document->dc_id_;
+        access_hash = web_document->access_hash_;
+        url = http_url.get_url();
+        file_name = get_url_query_file_name(http_url.query_);
+        mime_type = std::move(web_document->mime_type_);
+        size = web_document->size_;
+        break;
+      }
+      case telegram_api::webDocumentNoProxy::ID: {
+        is_web_no_proxy = true;
+        auto web_document = move_tl_object_as<telegram_api::webDocumentNoProxy>(web_document_ptr);
+
+        if (web_document->url_.find('.') == string::npos) {
+          LOG(ERROR) << "Receive invalid URL " << web_document->url_;
+          return {DocumentType::Unknown, FileId()};
+        }
+
+        url = std::move(web_document->url_);
+        file_name = get_url_file_name(url);
+        mime_type = std::move(web_document->mime_type_);
+        size = web_document->size_;
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+  }
+
+  LOG(DEBUG) << "Receive document with id = " << id << " of type " << static_cast<int32>(document_type);
+  if (!is_web_no_proxy && !DcId::is_valid(dc_id)) {
+    LOG(ERROR) << "Wrong dc_id = " << dc_id;
+    return {DocumentType::Unknown, FileId()};
+  }
+
+  auto suggested_file_name = file_name;
+  if (suggested_file_name.empty()) {
+    suggested_file_name = to_string(static_cast<uint64>(id));
+    auto extension = MimeType::to_extension(mime_type, default_extension);
+    if (!extension.empty()) {
+      suggested_file_name += '.';
+      suggested_file_name += extension;
+    }
+  }
+
+  FileId file_id;
+  if (!is_web) {
+    file_id = td_->file_manager_->register_remote(
+        FullRemoteFileLocation(file_type, id, access_hash, DcId::internal(dc_id)), FileLocationSource::FromServer,
+        owner_dialog_id, size, 0, suggested_file_name);
+    if (!encryption_key.empty()) {
+      td_->file_manager_->set_encryption_key(file_id, std::move(encryption_key));
+    }
+  } else if (!is_web_no_proxy) {
+    file_id =
+        td_->file_manager_->register_remote(FullRemoteFileLocation(file_type, url, access_hash, DcId::internal(dc_id)),
+                                            FileLocationSource::FromServer, owner_dialog_id, 0, size, file_name);
+  } else {
+    auto r_file_id = td_->file_manager_->from_persistent_id(url, file_type);
+    if (r_file_id.is_error()) {
+      LOG(ERROR) << "Can't register URL: " << r_file_id.error();
+      return {DocumentType::Unknown, FileId()};
+    }
+    file_id = r_file_id.move_as_ok();
+  }
+
+  if (dimensions.width != 0 && thumbnail.dimensions.width != 0) {
+    if ((thumbnail.dimensions.width < thumbnail.dimensions.height && dimensions.width > dimensions.height) ||
+        (thumbnail.dimensions.width > thumbnail.dimensions.height && dimensions.width < dimensions.height)) {
+      // fix for wrong dimensions specified by the Android application
+      std::swap(dimensions.width, dimensions.height);
+    }
+  }
+
+  switch (document_type) {
+    case DocumentType::Animation:
+      // TODO use has_stickers
+      td_->animations_manager_->create_animation(file_id, std::move(thumbnail), std::move(file_name),
+                                                 std::move(mime_type), video_duration, dimensions, !is_web);
+      break;
+    case DocumentType::Audio:
+      CHECK(audio != nullptr);
+      td_->audios_manager_->create_audio(file_id, std::move(thumbnail), std::move(file_name), std::move(mime_type),
+                                         audio->duration_, std::move(audio->title_), std::move(audio->performer_),
+                                         !is_web);
+      break;
+    case DocumentType::General:
+      td_->documents_manager_->create_document(file_id, std::move(thumbnail), std::move(file_name),
+                                               std::move(mime_type), !is_web);
+      break;
+    case DocumentType::Sticker:
+      CHECK(sticker != nullptr);
+      td_->stickers_manager_->create_sticker(file_id, std::move(thumbnail), dimensions, true, std::move(sticker),
+                                             load_data_multipromise_ptr);
+      break;
+    case DocumentType::Video:
+      td_->videos_manager_->create_video(file_id, std::move(thumbnail), has_stickers, vector<FileId>(),
+                                         std::move(file_name), std::move(mime_type), video_duration, dimensions,
+                                         supports_streaming, !is_web);
+      break;
+    case DocumentType::VideoNote:
+      td_->video_notes_manager_->create_video_note(file_id, std::move(thumbnail), video_duration, dimensions, !is_web);
+      break;
+    case DocumentType::VoiceNote:
+      CHECK(audio != nullptr);
+      td_->voice_notes_manager_->create_voice_note(file_id, std::move(mime_type), audio->duration_,
+                                                   audio->waveform_.as_slice().str(), !is_web);
+      break;
+    case DocumentType::Unknown:
+    default:
+      UNREACHABLE();
+  }
+  return {document_type, file_id};
+}
+
+FileId DocumentsManager::on_get_document(std::unique_ptr<Document> new_document, bool replace) {
+  auto file_id = new_document->file_id;
+  LOG(INFO) << "Receive document " << file_id;
+  auto &d = documents_[new_document->file_id];
+  if (d == nullptr) {
+    d = std::move(new_document);
+  } else if (replace) {
+    CHECK(d->file_id == new_document->file_id);
+    if (d->mime_type != new_document->mime_type) {
+      LOG(DEBUG) << "Document " << file_id << " mime_type has changed";
+      d->mime_type = new_document->mime_type;
+      d->is_changed = true;
+    }
+    if (d->file_name != new_document->file_name) {
+      LOG(DEBUG) << "Document " << file_id << " file_name has changed";
+      d->file_name = new_document->file_name;
+      d->is_changed = true;
+    }
+    if (d->thumbnail != new_document->thumbnail) {
+      if (!d->thumbnail.file_id.is_valid()) {
+        LOG(DEBUG) << "Document " << file_id << " thumbnail has changed";
+      } else {
+        LOG(INFO) << "Document " << file_id << " thumbnail has changed from " << d->thumbnail << " to "
+                  << new_document->thumbnail;
+      }
+      d->thumbnail = new_document->thumbnail;
+      d->is_changed = true;
+    }
+  }
+
+  return file_id;
+}
+
+void DocumentsManager::create_document(FileId file_id, PhotoSize thumbnail, string file_name, string mime_type,
+                                       bool replace) {
+  auto d = make_unique<Document>();
+  d->file_id = file_id;
+  d->file_name = std::move(file_name);
+  d->mime_type = std::move(mime_type);
+  d->thumbnail = std::move(thumbnail);
+  on_get_document(std::move(d), replace);
+}
+
+const DocumentsManager::Document *DocumentsManager::get_document(FileId file_id) const {
+  auto document = documents_.find(file_id);
+  if (document == documents_.end()) {
+    return nullptr;
+  }
+
+  CHECK(document->second->file_id == file_id);
+  return document->second.get();
+}
+
+bool DocumentsManager::has_input_media(FileId file_id, FileId thumbnail_file_id, bool is_secret) const {
+  auto file_view = td_->file_manager_->get_file_view(file_id);
+  if (is_secret) {
+    if (file_view.encryption_key().empty() || !file_view.has_remote_location()) {
+      return false;
+    }
+
+    return !thumbnail_file_id.is_valid();
+  } else {
+    if (file_view.is_encrypted()) {
+      return false;
+    }
+    return file_view.has_remote_location() || file_view.has_url();
+  }
+}
+
+SecretInputMedia DocumentsManager::get_secret_input_media(FileId document_file_id,
+                                                          tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                                          const string &caption, BufferSlice thumbnail) const {
+  const Document *document = get_document(document_file_id);
+  CHECK(document != nullptr);
+  auto file_view = td_->file_manager_->get_file_view(document_file_id);
+  auto &encryption_key = file_view.encryption_key();
+  if (encryption_key.empty()) {
+    return SecretInputMedia{};
+  }
+  if (file_view.has_remote_location()) {
+    input_file = file_view.remote_location().as_input_encrypted_file();
+  }
+  if (!input_file) {
+    return SecretInputMedia{};
+  }
+  if (document->thumbnail.file_id.is_valid() && thumbnail.empty()) {
+    return SecretInputMedia{};
+  }
+  vector<tl_object_ptr<secret_api::DocumentAttribute>> attributes;
+  if (document->file_name.size()) {
+    attributes.push_back(make_tl_object<secret_api::documentAttributeFilename>(document->file_name));
+  }
+  return SecretInputMedia{
+      std::move(input_file),
+      make_tl_object<secret_api::decryptedMessageMediaDocument>(
+          std::move(thumbnail), document->thumbnail.dimensions.width, document->thumbnail.dimensions.height,
+          document->mime_type, narrow_cast<int32>(file_view.size()), BufferSlice(encryption_key.key_slice()),
+          BufferSlice(encryption_key.iv_slice()), std::move(attributes), caption)};
+}
+
+tl_object_ptr<telegram_api::InputMedia> DocumentsManager::get_input_media(
+    FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file,
+    tl_object_ptr<telegram_api::InputFile> input_thumbnail) const {
+  auto file_view = td_->file_manager_->get_file_view(file_id);
+  if (file_view.is_encrypted()) {
+    return nullptr;
+  }
+  if (file_view.has_remote_location() && !file_view.remote_location().is_web()) {
+    return make_tl_object<telegram_api::inputMediaDocument>(0, file_view.remote_location().as_input_document(), 0);
+  }
+  if (file_view.has_url()) {
+    return make_tl_object<telegram_api::inputMediaDocumentExternal>(0, file_view.url(), 0);
+  }
+  CHECK(!file_view.has_remote_location());
+
+  const Document *document = get_document(file_id);
+  CHECK(document != nullptr);
+
+  if (input_file != nullptr) {
+    vector<tl_object_ptr<telegram_api::DocumentAttribute>> attributes;
+    if (document->file_name.size()) {
+      attributes.push_back(make_tl_object<telegram_api::documentAttributeFilename>(document->file_name));
+    }
+    int32 flags = 0;
+    if (input_thumbnail != nullptr) {
+      flags |= telegram_api::inputMediaUploadedDocument::THUMB_MASK;
+    }
+    return make_tl_object<telegram_api::inputMediaUploadedDocument>(
+        flags, false /*ignored*/, std::move(input_file), std::move(input_thumbnail), document->mime_type,
+        std::move(attributes), vector<tl_object_ptr<telegram_api::InputDocument>>(), 0);
+  }
+
+  return nullptr;
+}
+
+FileId DocumentsManager::get_document_thumbnail_file_id(FileId file_id) const {
+  auto document = get_document(file_id);
+  CHECK(document != nullptr);
+  return document->thumbnail.file_id;
+}
+
+void DocumentsManager::delete_document_thumbnail(FileId file_id) {
+  auto &document = documents_[file_id];
+  CHECK(document != nullptr);
+  document->thumbnail = PhotoSize();
+}
+
+FileId DocumentsManager::dup_document(FileId new_id, FileId old_id) {
+  const Document *old_document = get_document(old_id);
+  CHECK(old_document != nullptr);
+  auto &new_document = documents_[new_id];
+  CHECK(!new_document);
+  new_document = std::make_unique<Document>(*old_document);
+  new_document->file_id = new_id;
+  new_document->thumbnail.file_id = td_->file_manager_->dup_file_id(new_document->thumbnail.file_id);
+  return new_id;
+}
+
+bool DocumentsManager::merge_documents(FileId new_id, FileId old_id, bool can_delete_old) {
+  if (!old_id.is_valid()) {
+    LOG(ERROR) << "Old file id is invalid";
+    return true;
+  }
+
+  LOG(INFO) << "Merge documents " << new_id << " and " << old_id;
+  const Document *old_ = get_document(old_id);
+  CHECK(old_ != nullptr);
+  if (old_id == new_id) {
+    return old_->is_changed;
+  }
+
+  auto new_it = documents_.find(new_id);
+  if (new_it == documents_.end()) {
+    auto &old = documents_[old_id];
+    old->is_changed = true;
+    if (!can_delete_old) {
+      dup_document(new_id, old_id);
+    } else {
+      old->file_id = new_id;
+      documents_.emplace(new_id, std::move(old));
+    }
+  } else {
+    Document *new_ = new_it->second.get();
+    CHECK(new_ != nullptr);
+
+    if (old_->thumbnail != new_->thumbnail) {
+      //    LOG_STATUS(td_->file_manager_->merge(new_->thumbnail.file_id, old_->thumbnail.file_id));
+    }
+
+    new_->is_changed = true;
+  }
+  LOG_STATUS(td_->file_manager_->merge(new_id, old_id));
+  if (can_delete_old) {
+    documents_.erase(old_id);
+  }
+  return true;
+}
+
+string DocumentsManager::get_document_search_text(FileId file_id) const {
+  auto document = get_document(file_id);
+  CHECK(document);
+  if (document->file_name.size() > 32) {
+    return document->file_name;
+  }
+  auto buf = StackAllocator::alloc(256);
+  StringBuilder sb(buf.as_slice());
+  auto stem = PathView(document->file_name).file_stem();
+  sb << document->file_name;
+  for (size_t i = 1; i + 1 < stem.size(); i++) {
+    if (is_utf8_character_first_code_unit(stem[i])) {
+      sb << " " << stem.substr(0, i);
+    }
+  }
+  if (sb.is_error()) {
+    return document->file_name;
+  }
+  return sb.as_cslice().str();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/DocumentsManager.h b/libs/tdlib/td/td/telegram/DocumentsManager.h
new file mode 100644
index 0000000000..edbc02d657
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/DocumentsManager.h
@@ -0,0 +1,133 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/DialogId.h"
+#include "td/telegram/files/FileId.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/SecretInputMedia.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+
+#include <unordered_map>
+#include <utility>
+
+namespace td {
+class MultiPromiseActor;
+class Td;
+}  // namespace td
+
+namespace td {
+
+class DocumentsManager {
+ public:
+  explicit DocumentsManager(Td *td);
+
+  enum class DocumentType { Unknown, Animation, Audio, General, Sticker, Video, VideoNote, VoiceNote };
+
+  class RemoteDocument {
+   public:
+    tl_object_ptr<telegram_api::document> document;
+    // or
+    tl_object_ptr<telegram_api::encryptedFile> secret_file;
+    tl_object_ptr<secret_api::decryptedMessageMediaDocument> secret_document;
+    // or
+    tl_object_ptr<telegram_api::WebDocument> web_document;
+    PhotoSize thumbnail;
+
+    vector<tl_object_ptr<telegram_api::DocumentAttribute>> attributes;
+
+    RemoteDocument(tl_object_ptr<telegram_api::document> &&server_document)
+        : document(std::move(server_document))
+        , secret_file(nullptr)
+        , secret_document(nullptr)
+        , web_document(nullptr)
+        , thumbnail()
+        , attributes(std::move(document->attributes_)) {
+    }
+
+    RemoteDocument(tl_object_ptr<telegram_api::WebDocument> &&web_document, PhotoSize thumbnail,
+                   vector<tl_object_ptr<telegram_api::DocumentAttribute>> &&attributes)
+        : document(nullptr)
+        , secret_file(nullptr)
+        , secret_document(nullptr)
+        , web_document(std::move(web_document))
+        , thumbnail(std::move(thumbnail))
+        , attributes(std::move(attributes)) {
+    }
+
+    RemoteDocument(tl_object_ptr<telegram_api::encryptedFile> &&secret_file,
+                   tl_object_ptr<secret_api::decryptedMessageMediaDocument> &&secret_document,
+                   vector<tl_object_ptr<telegram_api::DocumentAttribute>> &&attributes)
+        : document(nullptr)
+        , secret_file(std::move(secret_file))
+        , secret_document(std::move(secret_document))
+        , web_document(nullptr)
+        , thumbnail()
+        , attributes(std::move(attributes)) {
+    }
+  };
+
+  tl_object_ptr<td_api::document> get_document_object(FileId file_id);
+
+  std::pair<DocumentType, FileId> on_get_document(RemoteDocument remote_document, DialogId owner_dialog_id,
+                                                  MultiPromiseActor *load_data_multipromise_ptr = nullptr,
+                                                  DocumentType default_document_type = DocumentType::General);
+
+  void create_document(FileId file_id, PhotoSize thumbnail, string file_name, string mime_type, bool replace);
+
+  bool has_input_media(FileId file_id, FileId thumbnail_file_id, bool is_secret) const;
+
+  SecretInputMedia get_secret_input_media(FileId document_file_id,
+                                          tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                          const string &caption, BufferSlice thumbnail) const;
+
+  tl_object_ptr<telegram_api::InputMedia> get_input_media(FileId file_id,
+                                                          tl_object_ptr<telegram_api::InputFile> input_file,
+                                                          tl_object_ptr<telegram_api::InputFile> input_thumbnail) const;
+
+  FileId get_document_thumbnail_file_id(FileId file_id) const;
+
+  void delete_document_thumbnail(FileId file_id);
+
+  FileId dup_document(FileId new_id, FileId old_id);
+
+  bool merge_documents(FileId new_id, FileId old_id, bool can_delete_old);
+
+  template <class T>
+  void store_document(FileId file_id, T &storer) const;
+
+  template <class T>
+  FileId parse_document(T &parser);
+
+  string get_document_search_text(FileId file_id) const;
+
+ private:
+  class Document {
+   public:
+    string file_name;
+    string mime_type;
+    PhotoSize thumbnail;
+    FileId file_id;
+
+    bool is_changed = true;
+  };
+
+  const Document *get_document(FileId file_id) const;
+
+  FileId on_get_document(std::unique_ptr<Document> new_document, bool replace);
+
+  Td *td_;
+  std::unordered_map<FileId, unique_ptr<Document>, FileIdHash> documents_;  // file_id -> Document
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/DocumentsManager.hpp b/libs/tdlib/td/td/telegram/DocumentsManager.hpp
new file mode 100644
index 0000000000..71b45cf274
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/DocumentsManager.hpp
@@ -0,0 +1,41 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/telegram/DocumentsManager.h"
+
+#include "td/telegram/files/FileId.hpp"
+#include "td/telegram/Photo.hpp"
+
+#include "td/utils/logging.h"
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+
+template <class T>
+void DocumentsManager::store_document(FileId file_id, T &storer) const {
+  LOG(DEBUG) << "Store document " << file_id;
+  auto it = documents_.find(file_id);
+  CHECK(it != documents_.end());
+  const Document *document = it->second.get();
+  store(document->file_name, storer);
+  store(document->mime_type, storer);
+  store(document->thumbnail, storer);
+  store(file_id, storer);
+}
+
+template <class T>
+FileId DocumentsManager::parse_document(T &parser) {
+  auto document = make_unique<Document>();
+  parse(document->file_name, parser);
+  parse(document->mime_type, parser);
+  parse(document->thumbnail, parser);
+  parse(document->file_id, parser);
+  LOG(DEBUG) << "Parsed document " << document->file_id;
+  return on_get_document(std::move(document), true);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Game.cpp b/libs/tdlib/td/td/telegram/Game.cpp
new file mode 100644
index 0000000000..000b4575d2
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Game.cpp
@@ -0,0 +1,121 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/Game.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/AnimationsManager.h"
+#include "td/telegram/ContactsManager.h"
+#include "td/telegram/DocumentsManager.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/Td.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+
+namespace td {
+
+Game::Game(Td *td, tl_object_ptr<telegram_api::game> &&game, DialogId owner_dialog_id)
+    : Game(td, std::move(game->title_), std::move(game->description_), std::move(game->photo_),
+           std::move(game->document_), owner_dialog_id) {
+  id_ = game->id_;
+  access_hash_ = game->access_hash_;
+  short_name_ = game->short_name_;
+}
+
+Game::Game(Td *td, string title, string description, tl_object_ptr<telegram_api::Photo> &&photo,
+           tl_object_ptr<telegram_api::Document> &&document, DialogId owner_dialog_id)
+    : title_(std::move(title)), description_(std::move(description)) {
+  CHECK(td != nullptr);
+  CHECK(photo != nullptr);
+  if (photo->get_id() == telegram_api::photo::ID) {
+    photo_ = get_photo(td->file_manager_.get(), move_tl_object_as<telegram_api::photo>(photo), owner_dialog_id);
+  }
+  if (document != nullptr) {
+    int32 document_id = document->get_id();
+    if (document_id == telegram_api::document::ID) {
+      auto parsed_document =
+          td->documents_manager_->on_get_document(move_tl_object_as<telegram_api::document>(document), owner_dialog_id);
+      switch (parsed_document.first) {
+        case DocumentsManager::DocumentType::Animation:
+          animation_file_id_ = parsed_document.second;
+          break;
+        case DocumentsManager::DocumentType::Audio:
+        case DocumentsManager::DocumentType::General:
+        case DocumentsManager::DocumentType::Sticker:
+        case DocumentsManager::DocumentType::Video:
+        case DocumentsManager::DocumentType::VideoNote:
+        case DocumentsManager::DocumentType::VoiceNote:
+        case DocumentsManager::DocumentType::Unknown:
+          LOG(ERROR) << "Receive non-animation document in the game";
+          break;
+        default:
+          UNREACHABLE();
+      }
+    }
+  }
+}
+
+Game::Game(UserId bot_user_id, string short_name) : bot_user_id_(bot_user_id), short_name_(std::move(short_name)) {
+  if (!bot_user_id_.is_valid()) {
+    bot_user_id_ = UserId();
+  }
+}
+
+bool Game::empty() const {
+  return short_name_.empty();
+}
+
+void Game::set_bot_user_id(UserId bot_user_id) {
+  if (bot_user_id.is_valid()) {
+    bot_user_id_ = bot_user_id;
+  } else {
+    bot_user_id_ = UserId();
+  }
+}
+
+UserId Game::get_bot_user_id() const {
+  return bot_user_id_;
+}
+
+void Game::set_message_text(FormattedText &&text) {
+  text_ = std::move(text);
+}
+
+tl_object_ptr<td_api::game> Game::get_game_object(const Td *td) const {
+  return make_tl_object<td_api::game>(
+      id_, short_name_, title_, get_formatted_text_object(text_), description_,
+      get_photo_object(td->file_manager_.get(), &photo_),
+      td->animations_manager_->get_animation_object(animation_file_id_, "get_game_object"));
+}
+
+tl_object_ptr<telegram_api::inputMediaGame> Game::get_input_media_game(const Td *td) const {
+  auto input_user = td->contacts_manager_->get_input_user(bot_user_id_);
+  CHECK(input_user != nullptr);
+  return make_tl_object<telegram_api::inputMediaGame>(
+      make_tl_object<telegram_api::inputGameShortName>(std::move(input_user), short_name_));
+}
+
+bool operator==(const Game &lhs, const Game &rhs) {
+  return lhs.id_ == rhs.id_ && lhs.access_hash_ == rhs.access_hash_ && lhs.bot_user_id_ == rhs.bot_user_id_ &&
+         lhs.short_name_ == rhs.short_name_ && lhs.title_ == rhs.title_ && lhs.description_ == rhs.description_ &&
+         lhs.photo_ == rhs.photo_ && lhs.animation_file_id_ == rhs.animation_file_id_ && lhs.text_ == rhs.text_;
+}
+
+bool operator!=(const Game &lhs, const Game &rhs) {
+  return !(lhs == rhs);
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const Game &game) {
+  return string_builder << "Game[id = " << game.id_ << ", access_hash = " << game.access_hash_
+                        << ", bot = " << game.bot_user_id_ << ", short_name = " << game.short_name_
+                        << ", title = " << game.title_ << ", description = " << game.description_
+                        << ", photo = " << game.photo_ << ", animation_file_id = " << game.animation_file_id_ << "]";
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Game.h b/libs/tdlib/td/td/telegram/Game.h
new file mode 100644
index 0000000000..4afe3031cc
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Game.h
@@ -0,0 +1,76 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/DialogId.h"
+#include "td/telegram/files/FileId.h"
+#include "td/telegram/MessageEntity.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/UserId.h"
+
+#include "td/utils/common.h"
+#include "td/utils/StringBuilder.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+namespace td {
+
+class Td;
+
+class Game {
+  int64 id_ = 0;
+  int64 access_hash_ = 0;
+  UserId bot_user_id_;
+  string short_name_;
+  string title_;
+  string description_;
+  Photo photo_;
+  FileId animation_file_id_;
+
+  FormattedText text_;
+
+  friend bool operator==(const Game &lhs, const Game &rhs);
+  friend bool operator!=(const Game &lhs, const Game &rhs);
+
+  friend StringBuilder &operator<<(StringBuilder &string_builder, const Game &game);
+
+ public:
+  Game() = default;
+
+  Game(Td *td, tl_object_ptr<telegram_api::game> &&game, DialogId owner_dialog_id);
+
+  Game(Td *td, string title, string description, tl_object_ptr<telegram_api::Photo> &&photo,
+       tl_object_ptr<telegram_api::Document> &&document, DialogId owner_dialog_id);
+
+  Game(UserId bot_user_id, string short_name);
+
+  bool empty() const;
+
+  void set_bot_user_id(UserId bot_user_id);
+
+  UserId get_bot_user_id() const;
+
+  void set_message_text(FormattedText &&text);
+
+  tl_object_ptr<td_api::game> get_game_object(const Td *td) const;
+
+  tl_object_ptr<telegram_api::inputMediaGame> get_input_media_game(const Td *td) const;
+
+  template <class StorerT>
+  void store(StorerT &storer) const;
+
+  template <class ParserT>
+  void parse(ParserT &parser);
+};
+
+bool operator==(const Game &lhs, const Game &rhs);
+bool operator!=(const Game &lhs, const Game &rhs);
+
+StringBuilder &operator<<(StringBuilder &string_builder, const Game &game);
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Game.hpp b/libs/tdlib/td/td/telegram/Game.hpp
new file mode 100644
index 0000000000..ba5b773d69
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Game.hpp
@@ -0,0 +1,60 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/telegram/Game.h"
+
+#include "td/telegram/AnimationsManager.hpp"
+#include "td/telegram/Photo.hpp"
+#include "td/telegram/Version.h"
+
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+
+template <class StorerT>
+void Game::store(StorerT &storer) const {
+  using td::store;
+  bool has_animation = animation_file_id_.is_valid();
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(has_animation);
+  END_STORE_FLAGS();
+  store(id_, storer);
+  store(access_hash_, storer);
+  store(bot_user_id_, storer);
+  store(short_name_, storer);
+  store(title_, storer);
+  store(description_, storer);
+  store(photo_, storer);
+  if (has_animation) {
+    storer.context()->td().get_actor_unsafe()->animations_manager_->store_animation(animation_file_id_, storer);
+  }
+  store(text_, storer);
+}
+
+template <class ParserT>
+void Game::parse(ParserT &parser) {
+  using td::parse;
+  bool has_animation = true;
+  if (parser.version() >= static_cast<int32>(Version::FixStoreGameWithoutAnimation)) {
+    BEGIN_PARSE_FLAGS();
+    PARSE_FLAG(has_animation);
+    END_PARSE_FLAGS();
+  }
+  parse(id_, parser);
+  parse(access_hash_, parser);
+  parse(bot_user_id_, parser);
+  parse(short_name_, parser);
+  parse(title_, parser);
+  parse(description_, parser);
+  parse(photo_, parser);
+  if (has_animation) {
+    animation_file_id_ = parser.context()->td().get_actor_unsafe()->animations_manager_->parse_animation(parser);
+  }
+  parse(text_, parser);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Global.cpp b/libs/tdlib/td/td/telegram/Global.cpp
new file mode 100644
index 0000000000..22a3e25323
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Global.cpp
@@ -0,0 +1,107 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/Global.h"
+
+#include "td/telegram/ConfigShared.h"
+#include "td/telegram/net/ConnectionCreator.h"
+#include "td/telegram/net/MtprotoHeader.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+#include "td/telegram/net/TempAuthKeyWatchdog.h"
+#include "td/telegram/TdDb.h"
+#include "td/telegram/Version.h"
+
+#include "td/actor/MultiPromise.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/utils/format.h"
+#include "td/utils/port/Clocks.h"
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+
+Global::Global() = default;
+
+Global::~Global() = default;
+
+void Global::close_all(Promise<> on_finished) {
+  td_db_->close_all(std::move(on_finished));
+  state_manager_.clear();
+  parameters_ = TdParameters();
+}
+void Global::close_and_destroy_all(Promise<> on_finished) {
+  td_db_->close_and_destroy_all(std::move(on_finished));
+  state_manager_.clear();
+  parameters_ = TdParameters();
+}
+
+ActorId<ConnectionCreator> Global::connection_creator() const {
+  return connection_creator_.get();
+}
+void Global::set_connection_creator(ActorOwn<ConnectionCreator> connection_creator) {
+  connection_creator_ = std::move(connection_creator);
+}
+
+ActorId<TempAuthKeyWatchdog> Global::temp_auth_key_watchdog() const {
+  return temp_auth_key_watchdog_.get();
+}
+void Global::set_temp_auth_key_watchdog(ActorOwn<TempAuthKeyWatchdog> actor) {
+  temp_auth_key_watchdog_ = std::move(actor);
+}
+
+const MtprotoHeader &Global::mtproto_header() const {
+  return *mtproto_header_;
+}
+void Global::set_mtproto_header(std::unique_ptr<MtprotoHeader> mtproto_header) {
+  mtproto_header_ = std::move(mtproto_header);
+}
+
+Status Global::init(const TdParameters &parameters, ActorId<Td> td, std::unique_ptr<TdDb> td_db) {
+  parameters_ = parameters;
+
+  gc_scheduler_id_ = min(Scheduler::instance()->sched_id() + 2, Scheduler::instance()->sched_count() - 1);
+  slow_net_scheduler_id_ = min(Scheduler::instance()->sched_id() + 3, Scheduler::instance()->sched_count() - 1);
+
+  td_ = td;
+  td_db_ = std::move(td_db);
+
+  string save_diff_str = this->td_db()->get_binlog_pmc()->get("server_time_difference");
+  if (save_diff_str.empty()) {
+    server_time_difference_ = Clocks::system() - Time::now();
+    server_time_difference_was_updated_ = false;
+  } else {
+    double save_diff;
+    unserialize(save_diff, save_diff_str).ensure();
+    double diff = save_diff + Clocks::system() - Time::now();
+    LOG(DEBUG) << "LOAD: " << tag("server_time_difference", diff);
+    server_time_difference_ = diff;
+    server_time_difference_was_updated_ = false;
+  }
+
+  return Status::OK();
+}
+
+void Global::update_server_time_difference(double diff) {
+  if (!server_time_difference_was_updated_ || server_time_difference_ < diff) {
+    server_time_difference_ = diff;
+    server_time_difference_was_updated_ = true;
+
+    // diff = server_time - Time::now
+    // save_diff = server_time - Clocks::system
+    double save_diff = diff + Time::now() - Clocks::system();
+    auto str = serialize(save_diff);
+    td_db()->get_binlog_pmc()->set("server_time_difference", str);
+  }
+}
+
+void Global::set_net_query_dispatcher(std::unique_ptr<NetQueryDispatcher> net_query_dispatcher) {
+  net_query_dispatcher_ = std::move(net_query_dispatcher);
+}
+void Global::set_shared_config(std::unique_ptr<ConfigShared> shared_config) {
+  shared_config_ = std::move(shared_config);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Global.h b/libs/tdlib/td/td/telegram/Global.h
new file mode 100644
index 0000000000..63c07d5c3c
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Global.h
@@ -0,0 +1,333 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/DhConfig.h"
+#include "td/telegram/net/NetQueryCreator.h"
+#include "td/telegram/TdDb.h"
+#include "td/telegram/TdParameters.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/Condition.h"
+#include "td/actor/PromiseFuture.h"
+#include "td/actor/SchedulerLocalStorage.h"
+
+#include "td/db/binlog/ConcurrentBinlog.h"
+#include "td/db/BinlogKeyValue.h"
+#include "td/db/Pmc.h"
+
+#include "td/net/NetStats.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/Time.h"
+
+#include <atomic>
+#include <memory>
+#include <mutex>
+
+namespace td {
+class AnimationsManager;
+class CallManager;
+class ConfigShared;
+class ConfigManager;
+class ConnectionCreator;
+class ContactsManager;
+class FileManager;
+class MtprotoHeader;
+class MessagesManager;
+class NetQueryDispatcher;
+class SecretChatsManager;
+class StateManager;
+class StickersManager;
+class StorageManager;
+class Td;
+class TempAuthKeyWatchdog;
+class TopDialogManager;
+class UpdatesManager;
+class WebPagesManager;
+};  // namespace td
+
+namespace td {
+class Global : public ActorContext {
+ public:
+  Global();
+  ~Global() override;
+  Global(const Global &) = delete;
+  Global &operator=(const Global &) = delete;
+  Global(Global &&other) = delete;
+  Global &operator=(Global &&other) = delete;
+
+  TdDb *td_db() {
+    CHECK(td_db_);
+    return td_db_.get();
+  }
+  void close_all(Promise<> on_finished);
+  void close_and_destroy_all(Promise<> on_finished);
+
+  Status init(const TdParameters &parameters, ActorId<Td> td, std::unique_ptr<TdDb> td_db) TD_WARN_UNUSED_RESULT;
+
+  Slice get_dir() const {
+    return parameters_.database_directory;
+  }
+  Slice get_files_dir() const {
+    return parameters_.files_directory;
+  }
+  bool is_test_dc() const {
+    return parameters_.use_test_dc;
+  }
+
+  NetQueryCreator &net_query_creator() {
+    return net_query_creator_.get();
+  }
+
+  void set_net_query_dispatcher(std::unique_ptr<NetQueryDispatcher> net_query_dispatcher);
+
+  NetQueryDispatcher &net_query_dispatcher() {
+    return *net_query_dispatcher_;
+  }
+
+  void set_shared_config(std::unique_ptr<ConfigShared> shared_config);
+
+  ConfigShared &shared_config() {
+    return *shared_config_;
+  }
+
+  double from_server_time(double date) const {
+    return date - get_server_time_difference();
+  }
+  double to_server_time(double now) const {
+    return now + get_server_time_difference();
+  }
+  double server_time() const {
+    return to_server_time(Time::now());
+  }
+  double server_time_cached() const {
+    return to_server_time(Time::now_cached());
+  }
+  int32 unix_time() const {
+    return static_cast<int32>(server_time());
+  }
+  int32 unix_time_cached() const {
+    return static_cast<int32>(server_time_cached());
+  }
+
+  void update_server_time_difference(double diff);
+
+  double get_server_time_difference() const {
+    return server_time_difference_.load(std::memory_order_relaxed);
+  }
+
+  ActorId<StateManager> state_manager() const {
+    return state_manager_;
+  }
+  void set_state_manager(ActorId<StateManager> state_manager) {
+    state_manager_ = state_manager;
+  }
+
+  ActorId<Td> td() const {
+    return td_;
+  }
+  ActorId<AnimationsManager> animations_manager() const {
+    return animations_manager_;
+  }
+  void set_animations_manager(ActorId<AnimationsManager> animations_manager) {
+    animations_manager_ = animations_manager;
+  }
+  ActorId<ContactsManager> contacts_manager() const {
+    return contacts_manager_;
+  }
+  void set_contacts_manager(ActorId<ContactsManager> contacts_manager) {
+    contacts_manager_ = contacts_manager;
+  }
+  ActorId<FileManager> file_manager() const {
+    return file_manager_;
+  }
+  void set_file_manager(ActorId<FileManager> file_manager) {
+    file_manager_ = std::move(file_manager);
+  }
+  ActorId<MessagesManager> messages_manager() const {
+    return messages_manager_;
+  }
+  void set_messages_manager(ActorId<MessagesManager> messages_manager) {
+    messages_manager_ = messages_manager;
+  }
+  ActorId<SecretChatsManager> secret_chats_manager() const {
+    return secret_chats_manager_;
+  }
+  void set_secret_chats_manager(ActorId<SecretChatsManager> secret_chats_manager) {
+    secret_chats_manager_ = secret_chats_manager;
+  }
+  ActorId<CallManager> call_manager() const {
+    return call_manager_;
+  }
+  void set_call_manager(ActorId<CallManager> call_manager) {
+    call_manager_ = call_manager;
+  }
+  ActorId<StickersManager> stickers_manager() const {
+    return stickers_manager_;
+  }
+  void set_stickers_manager(ActorId<StickersManager> stickers_manager) {
+    stickers_manager_ = stickers_manager;
+  }
+  ActorId<StorageManager> storage_manager() const {
+    return storage_manager_;
+  }
+  void set_storage_manager(ActorId<StorageManager> storage_manager) {
+    storage_manager_ = storage_manager;
+  }
+  ActorId<TopDialogManager> top_dialog_manager() const {
+    return top_dialog_manager_;
+  }
+  void set_top_dialog_manager(ActorId<TopDialogManager> top_dialog_manager) {
+    top_dialog_manager_ = top_dialog_manager;
+  }
+  ActorId<UpdatesManager> updates_manager() const {
+    return updates_manager_;
+  }
+  void set_updates_manager(ActorId<UpdatesManager> updates_manager) {
+    updates_manager_ = updates_manager;
+  }
+  ActorId<WebPagesManager> web_pages_manager() const {
+    return web_pages_manager_;
+  }
+  void set_web_pages_manager(ActorId<WebPagesManager> web_pages_manager) {
+    web_pages_manager_ = web_pages_manager;
+  }
+
+  ActorId<ConfigManager> config_manager() const {
+    return config_manager_;
+  }
+  void set_config_manager(ActorId<ConfigManager> config_manager) {
+    config_manager_ = config_manager;
+  }
+
+  ActorId<ConnectionCreator> connection_creator() const;
+  void set_connection_creator(ActorOwn<ConnectionCreator> connection_creator);
+
+  ActorId<TempAuthKeyWatchdog> temp_auth_key_watchdog() const;
+  void set_temp_auth_key_watchdog(ActorOwn<TempAuthKeyWatchdog> actor);
+
+  const MtprotoHeader &mtproto_header() const;
+  void set_mtproto_header(std::unique_ptr<MtprotoHeader> mtproto_header);
+
+  const TdParameters &parameters() const {
+    return parameters_;
+  }
+
+  int32 get_my_id() const {
+    return my_id_;
+  }
+  void set_my_id(int32 my_id) {
+    my_id_ = my_id;
+  }
+
+  int32 get_gc_scheduler_id() const {
+    return gc_scheduler_id_;
+  }
+
+  int32 get_slow_net_scheduler_id() const {
+    return slow_net_scheduler_id_;
+  }
+
+#if !TD_HAVE_ATOMIC_SHARED_PTR
+  std::mutex dh_config_mutex_;
+#endif
+
+  std::shared_ptr<DhConfig> get_dh_config() {
+#if !TD_HAVE_ATOMIC_SHARED_PTR
+    std::lock_guard<std::mutex> guard(dh_config_mutex_);
+    auto res = dh_config_;
+    return res;
+#else
+    return atomic_load(&dh_config_);
+#endif
+  }
+  void set_dh_config(std::shared_ptr<DhConfig> new_dh_config) {
+#if !TD_HAVE_ATOMIC_SHARED_PTR
+    std::lock_guard<std::mutex> guard(dh_config_mutex_);
+    dh_config_ = new_dh_config;
+#else
+    atomic_store(&dh_config_, std::move(new_dh_config));
+#endif
+  }
+
+  void wait_binlog_replay_finish(Promise<> promise) {
+    binlog_replay_finish_.wait(std::move(promise));
+  }
+
+  void on_binlog_replay_finish() {
+    binlog_replay_finish_.set_true();
+  }
+
+  void set_close_flag() {
+    close_flag_ = true;
+  }
+  bool close_flag() const {
+    return close_flag_.load();
+  }
+
+  const std::vector<std::shared_ptr<NetStatsCallback>> &get_net_stats_file_callbacks() {
+    return net_stats_file_callbacks_;
+  }
+  void set_net_stats_file_callbacks(std::vector<std::shared_ptr<NetStatsCallback>> callbacks) {
+    net_stats_file_callbacks_ = std::move(callbacks);
+  }
+
+ private:
+  std::shared_ptr<DhConfig> dh_config_;
+
+  std::unique_ptr<TdDb> td_db_;
+  Condition binlog_replay_finish_;
+
+  ActorId<Td> td_;
+  ActorId<AnimationsManager> animations_manager_;
+  ActorId<ContactsManager> contacts_manager_;
+  ActorId<FileManager> file_manager_;
+  ActorId<MessagesManager> messages_manager_;
+  ActorId<SecretChatsManager> secret_chats_manager_;
+  ActorId<CallManager> call_manager_;
+  ActorId<StickersManager> stickers_manager_;
+  ActorId<StorageManager> storage_manager_;
+  ActorId<TopDialogManager> top_dialog_manager_;
+  ActorId<UpdatesManager> updates_manager_;
+  ActorId<WebPagesManager> web_pages_manager_;
+  ActorId<ConfigManager> config_manager_;
+  ActorOwn<ConnectionCreator> connection_creator_;
+  ActorOwn<TempAuthKeyWatchdog> temp_auth_key_watchdog_;
+
+  std::unique_ptr<MtprotoHeader> mtproto_header_;
+
+  TdParameters parameters_;
+  int32 gc_scheduler_id_;
+  int32 slow_net_scheduler_id_;
+
+  std::atomic<double> server_time_difference_;
+  std::atomic<bool> server_time_difference_was_updated_;
+  std::atomic<bool> close_flag_{false};
+
+  std::vector<std::shared_ptr<NetStatsCallback>> net_stats_file_callbacks_;
+
+  ActorId<StateManager> state_manager_;
+
+  SchedulerLocalStorage<NetQueryCreator> net_query_creator_;
+  std::unique_ptr<NetQueryDispatcher> net_query_dispatcher_;
+
+  std::unique_ptr<ConfigShared> shared_config_;
+
+  int32 my_id_ = 0;  // hack
+
+  void do_close(Promise<> on_finish, bool destroy_flag);
+};
+
+inline Global *G() {
+  CHECK(Scheduler::context());
+  return static_cast<Global *>(Scheduler::context());
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/HashtagHints.cpp b/libs/tdlib/td/td/telegram/HashtagHints.cpp
new file mode 100644
index 0000000000..416835eb01
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/HashtagHints.cpp
@@ -0,0 +1,105 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/HashtagHints.h"
+
+#include "td/db/Pmc.h"
+#include "td/telegram/Global.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/tl_helpers.h"
+
+#include <functional>
+
+namespace td {
+
+HashtagHints::HashtagHints(string mode, ActorShared<> parent) : mode_(std::move(mode)), parent_(std::move(parent)) {
+}
+
+void HashtagHints::start_up() {
+  if (G()->parameters().use_file_db) {  // TODO hashtag hints should not depend on use_file_db
+    G()->td_db()->get_sqlite_pmc()->get(get_key(),
+                                        PromiseCreator::lambda([actor_id = actor_id(this)](Result<string> res) {
+                                          send_closure(actor_id, &HashtagHints::from_db, std::move(res), false);
+                                        }));
+  }
+}
+
+void HashtagHints::hashtag_used(const string &hashtag) {
+  if (!sync_with_db_) {
+    return;
+  }
+  hashtag_used_impl(hashtag);
+  G()->td_db()->get_sqlite_pmc()->set(get_key(), serialize(keys_to_strings(hints_.search_empty(101).second)),
+                                      Promise<>());
+}
+
+void HashtagHints::remove_hashtag(string hashtag, Promise<> promise) {
+  if (!sync_with_db_) {
+    promise.set_value(Unit());
+    return;
+  }
+  if (hashtag[0] == '#') {
+    hashtag = hashtag.substr(1);
+  }
+  auto key = std::hash<std::string>()(hashtag);
+  if (hints_.has_key(key)) {
+    hints_.remove(key);
+    G()->td_db()->get_sqlite_pmc()->set(get_key(), serialize(keys_to_strings(hints_.search_empty(101).second)),
+                                        Promise<>());
+    promise.set_value(Unit());  // set promise explicitly, because sqlite_pmc waits for too long before setting promise
+  } else {
+    promise.set_value(Unit());
+  }
+}
+
+void HashtagHints::query(const string &prefix, int32 limit, Promise<std::vector<string>> promise) {
+  if (!sync_with_db_) {
+    promise.set_value(std::vector<string>());
+    return;
+  }
+
+  auto result = prefix.empty() ? hints_.search_empty(limit) : hints_.search(prefix, limit);
+  promise.set_value(keys_to_strings(result.second));
+}
+
+string HashtagHints::get_key() const {
+  return "hashtag_hints#" + mode_;
+}
+
+void HashtagHints::hashtag_used_impl(const string &hashtag) {
+  // TODO: may be it should be optimized a little
+  auto key = std::hash<std::string>()(hashtag);
+  hints_.add(key, hashtag);
+  hints_.set_rating(key, -++counter_);
+}
+
+void HashtagHints::from_db(Result<string> data, bool dummy) {
+  sync_with_db_ = true;
+  if (data.is_error() || data.ok().empty()) {
+    return;
+  }
+  std::vector<string> hashtags;
+  auto status = unserialize(hashtags, data.ok());
+  if (status.is_error()) {
+    LOG(ERROR) << status;
+    return;
+  }
+
+  for (auto it = hashtags.rbegin(); it != hashtags.rend(); ++it) {
+    hashtag_used_impl(*it);
+  }
+}
+
+std::vector<string> HashtagHints::keys_to_strings(const std::vector<int64> &keys) {
+  std::vector<string> result;
+  result.reserve(keys.size());
+  for (auto &it : keys) {
+    result.push_back(hints_.key_to_string(it));
+  }
+  return result;
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/HashtagHints.h b/libs/tdlib/td/td/telegram/HashtagHints.h
new file mode 100644
index 0000000000..b99cc50cd6
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/HashtagHints.h
@@ -0,0 +1,43 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Hints.h"
+#include "td/utils/Status.h"
+
+namespace td {
+class HashtagHints : public Actor {
+ public:
+  HashtagHints(string mode, ActorShared<> parent);
+
+  void hashtag_used(const string &hashtag);
+
+  void remove_hashtag(string hashtag, Promise<> promise);
+
+  void query(const string &prefix, int32 limit, Promise<std::vector<string>> promise);
+
+ private:
+  string mode_;
+  Hints hints_;
+  bool sync_with_db_ = false;
+  int64 counter_ = 0;
+
+  ActorShared<> parent_;
+
+  string get_key() const;
+
+  void start_up() override;
+
+  void hashtag_used_impl(const string &hashtag);
+  void from_db(Result<string> data, bool dummy);
+  std::vector<string> keys_to_strings(const std::vector<int64> &keys);
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/InlineQueriesManager.cpp b/libs/tdlib/td/td/telegram/InlineQueriesManager.cpp
new file mode 100644
index 0000000000..c84aa8ce60
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/InlineQueriesManager.cpp
@@ -0,0 +1,1849 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/InlineQueriesManager.h"
+#include "td/telegram/td_api.h"
+#include "td/telegram/td_api.hpp"
+#include "td/telegram/telegram_api.h"
+#include "td/telegram/telegram_api.hpp"
+
+#include "td/telegram/AccessRights.h"
+#include "td/telegram/AnimationsManager.h"
+#include "td/telegram/AudiosManager.h"
+#include "td/telegram/AuthManager.h"
+#include "td/telegram/Contact.h"
+#include "td/telegram/ContactsManager.h"
+#include "td/telegram/DocumentsManager.h"
+#include "td/telegram/files/FileManager.h"
+#include "td/telegram/Game.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/MessageEntity.h"
+#include "td/telegram/MessagesManager.h"
+#include "td/telegram/misc.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/ReplyMarkup.h"
+#include "td/telegram/StickersManager.h"
+#include "td/telegram/Td.h"
+#include "td/telegram/VideoNotesManager.h"
+#include "td/telegram/VideosManager.h"
+#include "td/telegram/VoiceNotesManager.h"
+#include "td/telegram/WebPageId.h"
+#include "td/telegram/WebPagesManager.h"
+
+#include "td/telegram/net/DcId.h"
+
+#include "td/utils/base64.h"
+#include "td/utils/buffer.h"
+#include "td/utils/HttpUrl.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Time.h"
+#include "td/utils/tl_helpers.h"
+#include "td/utils/tl_parsers.h"
+
+#include <algorithm>
+#include <functional>
+
+namespace td {
+
+class GetInlineBotResultsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  UserId bot_user_id_;
+  uint64 query_hash_;
+
+  static constexpr int32 GET_INLINE_BOT_RESULTS_FLAG_HAS_LOCATION = 1 << 0;
+
+ public:
+  explicit GetInlineBotResultsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  NetQueryRef send(UserId bot_user_id, tl_object_ptr<telegram_api::InputUser> bot_input_user, DialogId dialog_id,
+                   Location user_location, const string &query, const string &offset, uint64 query_hash) {
+    bot_user_id_ = bot_user_id;
+    query_hash_ = query_hash;
+    int32 flags = 0;
+    if (!user_location.empty()) {
+      flags |= GET_INLINE_BOT_RESULTS_FLAG_HAS_LOCATION;
+    }
+
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Read);
+    if (input_peer == nullptr) {
+      input_peer = make_tl_object<telegram_api::inputPeerEmpty>();
+    }
+
+    auto net_query = G()->net_query_creator().create(create_storer(telegram_api::messages_getInlineBotResults(
+        flags, std::move(bot_input_user), std::move(input_peer),
+        user_location.empty() ? nullptr : user_location.get_input_geo_point(), query, offset)));
+    auto result = net_query.get_weak();
+    net_query->need_resend_on_503 = false;
+    send_query(std::move(net_query));
+    return result;
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getInlineBotResults>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->inline_queries_manager_->on_get_inline_query_results(bot_user_id_, query_hash_, result_ptr.move_as_ok());
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.code() == NetQuery::Cancelled) {
+      status = Status::Error(406, "Request cancelled");
+    }
+    LOG(INFO) << "Inline query returned error " << status;
+
+    td->inline_queries_manager_->on_get_inline_query_results(bot_user_id_, query_hash_, nullptr);
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SetInlineBotResultsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit SetInlineBotResultsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int64 inline_query_id, bool is_gallery, bool is_personal,
+            vector<tl_object_ptr<telegram_api::InputBotInlineResult>> &&results, int32 cache_time,
+            const string &next_offset, const string &switch_pm_text, const string &switch_pm_parameter) {
+    int32 flags = 0;
+    if (is_gallery) {
+      flags |= telegram_api::messages_setInlineBotResults::GALLERY_MASK;
+    }
+    if (is_personal) {
+      flags |= telegram_api::messages_setInlineBotResults::PRIVATE_MASK;
+    }
+    if (!next_offset.empty()) {
+      flags |= telegram_api::messages_setInlineBotResults::NEXT_OFFSET_MASK;
+    }
+    tl_object_ptr<telegram_api::inlineBotSwitchPM> inline_bot_switch_pm;
+    if (!switch_pm_text.empty()) {
+      flags |= telegram_api::messages_setInlineBotResults::SWITCH_PM_MASK;
+      inline_bot_switch_pm = make_tl_object<telegram_api::inlineBotSwitchPM>(switch_pm_text, switch_pm_parameter);
+    }
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_setInlineBotResults(
+        flags, false /*ignored*/, false /*ignored*/, inline_query_id, std::move(results), cache_time, next_offset,
+        std::move(inline_bot_switch_pm)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_setInlineBotResults>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    if (!result) {
+      LOG(INFO) << "Sending answer to an inline query has failed";
+    }
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+InlineQueriesManager::InlineQueriesManager(Td *td, ActorShared<> parent) : td_(td), parent_(std::move(parent)) {
+  drop_inline_query_result_timeout_.set_callback(on_drop_inline_query_result_timeout_callback);
+  drop_inline_query_result_timeout_.set_callback_data(static_cast<void *>(this));
+}
+
+void InlineQueriesManager::tear_down() {
+  parent_.reset();
+}
+
+void InlineQueriesManager::on_drop_inline_query_result_timeout_callback(void *inline_queries_manager_ptr,
+                                                                        int64 query_hash) {
+  auto inline_queries_manager = static_cast<InlineQueriesManager *>(inline_queries_manager_ptr);
+  auto it = inline_queries_manager->inline_query_results_.find(query_hash);
+  CHECK(it != inline_queries_manager->inline_query_results_.end());
+  CHECK(it->second.results != nullptr);
+  CHECK(it->second.pending_request_count >= 0);
+  if (it->second.pending_request_count == 0) {
+    inline_queries_manager->inline_query_results_.erase(it);
+  }
+}
+
+void InlineQueriesManager::after_get_difference() {
+  if (recently_used_bots_loaded_ < 2) {
+    Promise<Unit> promise;
+    load_recently_used_bots(promise);
+  }
+}
+
+tl_object_ptr<telegram_api::inputBotInlineMessageID> InlineQueriesManager::get_input_bot_inline_message_id(
+    const string &inline_message_id) {
+  auto r_binary = base64url_decode(inline_message_id);
+  if (r_binary.is_error()) {
+    return nullptr;
+  }
+  BufferSlice buffer_slice(r_binary.ok());
+  TlBufferParser parser(&buffer_slice);
+  auto result = telegram_api::inputBotInlineMessageID::fetch(parser);
+  parser.fetch_end();
+  if (parser.get_error()) {
+    return nullptr;
+  }
+  if (!DcId::is_valid(result->dc_id_)) {
+    return nullptr;
+  }
+  LOG(INFO) << "Have inline message id: " << to_string(result);
+  return result;
+}
+
+string InlineQueriesManager::get_inline_message_id(
+    tl_object_ptr<telegram_api::inputBotInlineMessageID> &&input_bot_inline_message_id) {
+  if (input_bot_inline_message_id == nullptr) {
+    return "";
+  }
+  LOG(INFO) << "Got inline message id: " << to_string(input_bot_inline_message_id);
+
+  return base64url_encode(serialize(*input_bot_inline_message_id));
+}
+
+Result<FormattedText> InlineQueriesManager::process_input_caption(
+    td_api::object_ptr<td_api::formattedText> &&caption) const {
+  return td_->messages_manager_->process_input_caption(DialogId(), std::move(caption), true);
+}
+
+tl_object_ptr<telegram_api::inputBotInlineMessageMediaAuto>
+InlineQueriesManager::get_input_bot_inline_message_media_auto(
+    const FormattedText &caption, tl_object_ptr<telegram_api::ReplyMarkup> &&input_reply_markup) const {
+  int32 flags = 0;
+  if (input_reply_markup != nullptr) {
+    flags |= telegram_api::inputBotInlineMessageText::REPLY_MARKUP_MASK;
+  }
+  auto entities = get_input_message_entities(td_->contacts_manager_.get(), caption.entities);
+  if (!entities.empty()) {
+    flags |= telegram_api::inputBotInlineMessageText::ENTITIES_MASK;
+  }
+
+  return make_tl_object<telegram_api::inputBotInlineMessageMediaAuto>(flags, caption.text, std::move(entities),
+                                                                      std::move(input_reply_markup));
+}
+
+Result<tl_object_ptr<telegram_api::InputBotInlineMessage>> InlineQueriesManager::get_inline_message(
+    tl_object_ptr<td_api::InputMessageContent> &&input_message_content,
+    tl_object_ptr<td_api::ReplyMarkup> &&reply_markup_ptr, int32 allowed_media_content_id) const {
+  if (input_message_content == nullptr) {
+    return Status::Error(400, "Inline message can't be empty");
+  }
+  TRY_RESULT(reply_markup, get_reply_markup(std::move(reply_markup_ptr), true, true, false, true));
+  auto input_reply_markup = get_input_reply_markup(reply_markup);
+  int32 flags = 0;
+  if (input_reply_markup != nullptr) {
+    flags |= telegram_api::inputBotInlineMessageText::REPLY_MARKUP_MASK;
+  }
+
+  auto constructor_id = input_message_content->get_id();
+  if (constructor_id == td_api::inputMessageText::ID) {
+    TRY_RESULT(input_message_text,
+               td_->messages_manager_->process_input_message_text(DialogId(), std::move(input_message_content), true));
+
+    if (input_message_text.disable_web_page_preview) {
+      flags |= telegram_api::inputBotInlineMessageText::NO_WEBPAGE_MASK;
+    }
+    if (!input_message_text.text.entities.empty()) {
+      flags |= telegram_api::inputBotInlineMessageText::ENTITIES_MASK;
+    }
+    return make_tl_object<telegram_api::inputBotInlineMessageText>(
+        flags, false /*ignored*/, std::move(input_message_text.text.text),
+        get_input_message_entities(td_->contacts_manager_.get(), input_message_text.text.entities),
+        std::move(input_reply_markup));
+  }
+  if (constructor_id == td_api::inputMessageContact::ID) {
+    TRY_RESULT(contact, MessagesManager::process_input_message_contact(std::move(input_message_content)));
+    return contact.get_input_bot_inline_message_media_contact(flags, std::move(input_reply_markup));
+  }
+  if (constructor_id == td_api::inputMessageLocation::ID) {
+    TRY_RESULT(location, MessagesManager::process_input_message_location(std::move(input_message_content)));
+    return make_tl_object<telegram_api::inputBotInlineMessageMediaGeo>(flags, location.first.get_input_geo_point(),
+                                                                       location.second, std::move(input_reply_markup));
+  }
+  if (constructor_id == td_api::inputMessageVenue::ID) {
+    TRY_RESULT(venue, MessagesManager::process_input_message_venue(std::move(input_message_content)));
+    return venue.get_input_bot_inline_message_media_venue(flags, std::move(input_reply_markup));
+  }
+  if (constructor_id == allowed_media_content_id) {
+    if (constructor_id == td_api::inputMessageAnimation::ID) {
+      auto input_message_animation = static_cast<td_api::inputMessageAnimation *>(input_message_content.get());
+      TRY_RESULT(caption, process_input_caption(std::move(input_message_animation->caption_)));
+      return get_input_bot_inline_message_media_auto(caption, std::move(input_reply_markup));
+    }
+    if (constructor_id == td_api::inputMessageAudio::ID) {
+      auto input_message_audio = static_cast<td_api::inputMessageAudio *>(input_message_content.get());
+      TRY_RESULT(caption, process_input_caption(std::move(input_message_audio->caption_)));
+      return get_input_bot_inline_message_media_auto(caption, std::move(input_reply_markup));
+    }
+    if (constructor_id == td_api::inputMessageDocument::ID) {
+      auto input_message_document = static_cast<td_api::inputMessageDocument *>(input_message_content.get());
+      TRY_RESULT(caption, process_input_caption(std::move(input_message_document->caption_)));
+      return get_input_bot_inline_message_media_auto(caption, std::move(input_reply_markup));
+    }
+    if (constructor_id == td_api::inputMessagePhoto::ID) {
+      auto input_message_photo = static_cast<td_api::inputMessagePhoto *>(input_message_content.get());
+      TRY_RESULT(caption, process_input_caption(std::move(input_message_photo->caption_)));
+      return get_input_bot_inline_message_media_auto(caption, std::move(input_reply_markup));
+    }
+    if (constructor_id == td_api::inputMessageSticker::ID) {
+      // auto input_message_sticker = static_cast<const td_api::inputMessageSticker *>(input_message_content.get());
+      return make_tl_object<telegram_api::inputBotInlineMessageMediaAuto>(flags, "", Auto(),
+                                                                          std::move(input_reply_markup));
+    }
+    if (constructor_id == td_api::inputMessageVideo::ID) {
+      auto input_message_video = static_cast<td_api::inputMessageVideo *>(input_message_content.get());
+      TRY_RESULT(caption, process_input_caption(std::move(input_message_video->caption_)));
+      return get_input_bot_inline_message_media_auto(caption, std::move(input_reply_markup));
+    }
+    if (constructor_id == td_api::inputMessageVoiceNote::ID) {
+      auto input_message_voice_note = static_cast<td_api::inputMessageVoiceNote *>(input_message_content.get());
+      TRY_RESULT(caption, process_input_caption(std::move(input_message_voice_note->caption_)));
+      return get_input_bot_inline_message_media_auto(caption, std::move(input_reply_markup));
+    }
+  }
+  return Status::Error(400, "Unallowed inline message content type");
+}
+
+bool InlineQueriesManager::register_inline_message_content(
+    int64 query_id, const string &result_id, FileId file_id,
+    tl_object_ptr<telegram_api::BotInlineMessage> &&inline_message, int32 allowed_media_content_id, Photo *photo,
+    Game *game) {
+  CHECK(inline_message != nullptr);
+  CHECK((allowed_media_content_id == td_api::inputMessagePhoto::ID) == (photo != nullptr));
+  CHECK((allowed_media_content_id == td_api::inputMessageGame::ID) == (game != nullptr));
+  CHECK((allowed_media_content_id != td_api::inputMessagePhoto::ID &&
+         allowed_media_content_id != td_api::inputMessageGame::ID && allowed_media_content_id != -1) ==
+        file_id.is_valid());
+
+  unique_ptr<MessageContent> message_content;
+  tl_object_ptr<telegram_api::ReplyMarkup> reply_markup;
+  bool disable_web_page_preview = false;
+  switch (inline_message->get_id()) {
+    case telegram_api::botInlineMessageText::ID: {
+      auto inline_message_text = move_tl_object_as<telegram_api::botInlineMessageText>(inline_message);
+      auto entities = get_message_entities(td_->contacts_manager_.get(), std::move(inline_message_text->entities_),
+                                           "botInlineMessageText");
+      auto status = fix_formatted_text(inline_message_text->message_, entities, false, true, true, false);
+      if (status.is_error()) {
+        LOG(ERROR) << "Receive error " << status << " while parsing botInlineMessageText "
+                   << inline_message_text->message_;
+        break;
+      }
+
+      disable_web_page_preview =
+          (inline_message_text->flags_ & telegram_api::botInlineMessageText::NO_WEBPAGE_MASK) != 0;
+      WebPageId web_page_id;
+      if (!disable_web_page_preview) {
+        web_page_id =
+            td_->web_pages_manager_->get_web_page_by_url(get_first_url(inline_message_text->message_, entities));
+      }
+      message_content = make_unique<MessageText>(
+          FormattedText{std::move(inline_message_text->message_), std::move(entities)}, web_page_id);
+      reply_markup = std::move(inline_message_text->reply_markup_);
+      break;
+    }
+    case telegram_api::botInlineMessageMediaGeo::ID: {
+      auto inline_message_geo = move_tl_object_as<telegram_api::botInlineMessageMediaGeo>(inline_message);
+      if (inline_message_geo->period_ > 0) {
+        message_content =
+            make_unique<MessageLiveLocation>(Location(inline_message_geo->geo_), inline_message_geo->period_);
+      } else {
+        message_content = make_unique<MessageLocation>(Location(inline_message_geo->geo_));
+      }
+      reply_markup = std::move(inline_message_geo->reply_markup_);
+      break;
+    }
+    case telegram_api::botInlineMessageMediaVenue::ID: {
+      auto inline_message_venue = move_tl_object_as<telegram_api::botInlineMessageMediaVenue>(inline_message);
+      message_content = make_unique<MessageVenue>(
+          Venue(inline_message_venue->geo_, std::move(inline_message_venue->title_),
+                std::move(inline_message_venue->address_), std::move(inline_message_venue->provider_),
+                std::move(inline_message_venue->venue_id_)));
+      reply_markup = std::move(inline_message_venue->reply_markup_);
+      break;
+    }
+    case telegram_api::botInlineMessageMediaContact::ID: {
+      auto inline_message_contact = move_tl_object_as<telegram_api::botInlineMessageMediaContact>(inline_message);
+      message_content = make_unique<MessageContact>(Contact(inline_message_contact->phone_number_,
+                                                            inline_message_contact->first_name_,
+                                                            inline_message_contact->last_name_, 0));
+      reply_markup = std::move(inline_message_contact->reply_markup_);
+      break;
+    }
+    case telegram_api::botInlineMessageMediaAuto::ID: {
+      auto input_message_media_auto = move_tl_object_as<telegram_api::botInlineMessageMediaAuto>(inline_message);
+      auto caption = td_->messages_manager_->get_message_text(input_message_media_auto->message_,
+                                                              std::move(input_message_media_auto->entities_), 0);
+      reply_markup = std::move(input_message_media_auto->reply_markup_);
+
+      if (allowed_media_content_id == td_api::inputMessageAnimation::ID) {
+        message_content = make_unique<MessageAnimation>(file_id, std::move(caption));
+      } else if (allowed_media_content_id == td_api::inputMessageAudio::ID) {
+        message_content = make_unique<MessageAudio>(file_id, std::move(caption));
+      } else if (allowed_media_content_id == td_api::inputMessageDocument::ID) {
+        message_content = make_unique<MessageDocument>(file_id, std::move(caption));
+      } else if (allowed_media_content_id == td_api::inputMessageGame::ID) {
+        CHECK(game != nullptr);
+        // TODO game->set_short_name(std::move(caption));
+        message_content = make_unique<MessageGame>(std::move(*game));
+      } else if (allowed_media_content_id == td_api::inputMessagePhoto::ID) {
+        message_content = make_unique<MessagePhoto>(std::move(*photo), std::move(caption));
+      } else if (allowed_media_content_id == td_api::inputMessageSticker::ID) {
+        message_content = make_unique<MessageSticker>(file_id);
+      } else if (allowed_media_content_id == td_api::inputMessageVideo::ID) {
+        message_content = make_unique<MessageVideo>(file_id, std::move(caption));
+      } else if (allowed_media_content_id == td_api::inputMessageVoiceNote::ID) {
+        message_content = make_unique<MessageVoiceNote>(file_id, std::move(caption), true);
+      } else {
+        input_message_media_auto->reply_markup_ = std::move(reply_markup);
+        input_message_media_auto->message_ = std::move(caption.text);
+        inline_message = std::move(input_message_media_auto);
+      }
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+  if (message_content != nullptr) {
+    inline_message_contents_[query_id][result_id] = {
+        std::move(message_content),
+        get_reply_markup(std::move(reply_markup), td_->auth_manager_->is_bot(), true, false), disable_web_page_preview};
+    return true;
+  }
+
+  LOG(WARNING) << "Unallowed bot inline message " << to_string(inline_message);
+  return false;
+}
+
+std::tuple<const MessageContent *, const ReplyMarkup *, bool> InlineQueriesManager::get_inline_message_content(
+    int64 query_id, const string &result_id) {
+  auto it = inline_message_contents_.find(query_id);
+  if (it == inline_message_contents_.end()) {
+    return std::make_tuple(nullptr, nullptr, false);
+  }
+
+  auto result_it = it->second.find(result_id);
+  if (result_it == it->second.end()) {
+    return std::make_tuple(nullptr, nullptr, false);
+  }
+
+  if (update_bot_usage(get_inline_bot_user_id(query_id))) {
+    save_recently_used_bots();
+  }
+  return std::make_tuple(result_it->second.message_content.get(), result_it->second.message_reply_markup.get(),
+                         result_it->second.disable_web_page_preview);
+}
+
+UserId InlineQueriesManager::get_inline_bot_user_id(int64 query_id) const {
+  auto it = query_id_to_bot_user_id_.find(query_id);
+  if (it == query_id_to_bot_user_id_.end()) {
+    return UserId();
+  }
+  return it->second;
+}
+
+void InlineQueriesManager::answer_inline_query(int64 inline_query_id, bool is_personal,
+                                               vector<tl_object_ptr<td_api::InputInlineQueryResult>> &&input_results,
+                                               int32 cache_time, const string &next_offset,
+                                               const string &switch_pm_text, const string &switch_pm_parameter,
+                                               Promise<Unit> &&promise) const {
+  if (!td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(400, "Method can be used by bots only"));
+  }
+
+  vector<tl_object_ptr<telegram_api::InputBotInlineResult>> results;
+
+  bool is_gallery = false;
+  bool force_vertical = false;
+  for (auto &input_result : input_results) {
+    if (input_result == nullptr) {
+      return promise.set_error(Status::Error(400, "Inline query result must not be empty"));
+    }
+
+    string id;
+    string url;
+    string type;
+    string title;
+    string description;
+    string thumbnail_url;
+    string content_url;
+    string content_type;
+    int32 thumbnail_width = 0;
+    int32 thumbnail_height = 0;
+    int32 width = 0;
+    int32 height = 0;
+    int32 duration = 0;
+
+    FileType file_type = FileType::Temp;
+    Result<tl_object_ptr<telegram_api::InputBotInlineMessage>> r_inline_message;
+    switch (input_result->get_id()) {
+      case td_api::inputInlineQueryResultAnimatedGif::ID: {
+        auto animated_gif = move_tl_object_as<td_api::inputInlineQueryResultAnimatedGif>(input_result);
+        type = "gif";
+        id = std::move(animated_gif->id_);
+        title = std::move(animated_gif->title_);
+        thumbnail_url = std::move(animated_gif->thumbnail_url_);
+        content_url = std::move(animated_gif->gif_url_);
+        content_type = "image/gif";
+        // duration = animated_gif->gif_duration_;
+        width = animated_gif->gif_width_;
+        height = animated_gif->gif_height_;
+        is_gallery = true;
+
+        file_type = FileType::Animation;
+        r_inline_message =
+            get_inline_message(std::move(animated_gif->input_message_content_), std::move(animated_gif->reply_markup_),
+                               td_api::inputMessageAnimation::ID);
+        break;
+      }
+      case td_api::inputInlineQueryResultAnimatedMpeg4::ID: {
+        auto animated_mpeg4 = move_tl_object_as<td_api::inputInlineQueryResultAnimatedMpeg4>(input_result);
+        type = "gif";
+        id = std::move(animated_mpeg4->id_);
+        title = std::move(animated_mpeg4->title_);
+        thumbnail_url = std::move(animated_mpeg4->thumbnail_url_);
+        content_url = std::move(animated_mpeg4->mpeg4_url_);
+        content_type = "video/mp4";
+        duration = animated_mpeg4->mpeg4_duration_;
+        width = animated_mpeg4->mpeg4_width_;
+        height = animated_mpeg4->mpeg4_height_;
+        is_gallery = true;
+
+        file_type = FileType::Animation;
+        r_inline_message =
+            get_inline_message(std::move(animated_mpeg4->input_message_content_),
+                               std::move(animated_mpeg4->reply_markup_), td_api::inputMessageAnimation::ID);
+        break;
+      }
+      case td_api::inputInlineQueryResultArticle::ID: {
+        auto article = move_tl_object_as<td_api::inputInlineQueryResultArticle>(input_result);
+        type = "article";
+        id = std::move(article->id_);
+        if (!article->url_.empty()) {
+          content_url = std::move(article->url_);
+          content_type = "text/html";
+          if (!article->hide_url_) {
+            url = content_url;
+          }
+        }
+        title = std::move(article->title_);
+        description = std::move(article->description_);
+        thumbnail_url = std::move(article->thumbnail_url_);
+        if (!thumbnail_url.empty()) {
+          thumbnail_width = article->thumbnail_width_;
+          thumbnail_height = article->thumbnail_height_;
+        }
+        force_vertical = true;
+
+        r_inline_message =
+            get_inline_message(std::move(article->input_message_content_), std::move(article->reply_markup_), -1);
+        break;
+      }
+      case td_api::inputInlineQueryResultAudio::ID: {
+        auto audio = move_tl_object_as<td_api::inputInlineQueryResultAudio>(input_result);
+        type = "audio";
+        id = std::move(audio->id_);
+        title = std::move(audio->title_);
+        description = std::move(audio->performer_);
+        content_url = std::move(audio->audio_url_);
+        content_type = "audio/mpeg";
+        duration = audio->audio_duration_;
+        force_vertical = true;
+
+        file_type = FileType::Audio;
+        r_inline_message = get_inline_message(std::move(audio->input_message_content_), std::move(audio->reply_markup_),
+                                              td_api::inputMessageAudio::ID);
+        break;
+      }
+      case td_api::inputInlineQueryResultContact::ID: {
+        auto contact = move_tl_object_as<td_api::inputInlineQueryResultContact>(input_result);
+        type = "contact";
+        id = std::move(contact->id_);
+        string phone_number = trim(contact->contact_->phone_number_);
+        string first_name = trim(contact->contact_->first_name_);
+        string last_name = trim(contact->contact_->last_name_);
+        if (phone_number.empty()) {
+          return promise.set_error(Status::Error(400, "Field \"phone_number\" must contain a valid phone number"));
+        }
+        if (first_name.empty()) {
+          return promise.set_error(Status::Error(400, "Field \"first_name\" should be non-empty"));
+        }
+        title = last_name.empty() ? first_name : first_name + " " + last_name;
+        description = std::move(phone_number);
+        thumbnail_url = std::move(contact->thumbnail_url_);
+        if (!thumbnail_url.empty()) {
+          thumbnail_width = contact->thumbnail_width_;
+          thumbnail_height = contact->thumbnail_height_;
+        }
+        force_vertical = true;
+
+        r_inline_message =
+            get_inline_message(std::move(contact->input_message_content_), std::move(contact->reply_markup_), -1);
+        break;
+      }
+      case td_api::inputInlineQueryResultDocument::ID: {
+        auto document = move_tl_object_as<td_api::inputInlineQueryResultDocument>(input_result);
+        type = "file";
+        id = std::move(document->id_);
+        title = std::move(document->title_);
+        description = std::move(document->description_);
+        thumbnail_url = std::move(document->thumbnail_url_);
+        content_url = std::move(document->document_url_);
+        content_type = std::move(document->mime_type_);
+        thumbnail_width = document->thumbnail_width_;
+        thumbnail_height = document->thumbnail_height_;
+
+        if (content_url.find('.') != string::npos) {
+          if (begins_with(content_type, "application/pdf")) {
+            content_type = "application/pdf";
+          } else if (begins_with(content_type, "application/zip")) {
+            content_type = "application/zip";
+          } else {
+            return promise.set_error(Status::Error(400, "Unallowed document MIME type"));
+          }
+        }
+
+        file_type = FileType::Document;
+        r_inline_message = get_inline_message(std::move(document->input_message_content_),
+                                              std::move(document->reply_markup_), td_api::inputMessageDocument::ID);
+        break;
+      }
+      case td_api::inputInlineQueryResultGame::ID: {
+        auto game = move_tl_object_as<td_api::inputInlineQueryResultGame>(input_result);
+        auto r_reply_markup = get_reply_markup(std::move(game->reply_markup_), true, true, false, true);
+        if (r_reply_markup.is_error()) {
+          return promise.set_error(r_reply_markup.move_as_error());
+        }
+
+        auto input_reply_markup = get_input_reply_markup(r_reply_markup.ok());
+        int32 flags = 0;
+        if (input_reply_markup != nullptr) {
+          flags |= telegram_api::inputBotInlineMessageGame::REPLY_MARKUP_MASK;
+        }
+        auto result = make_tl_object<telegram_api::inputBotInlineResultGame>(
+            game->id_, game->game_short_name_,
+            make_tl_object<telegram_api::inputBotInlineMessageGame>(flags, std::move(input_reply_markup)));
+        results.push_back(std::move(result));
+        continue;
+      }
+      case td_api::inputInlineQueryResultLocation::ID: {
+        auto location = move_tl_object_as<td_api::inputInlineQueryResultLocation>(input_result);
+        type = "geo";
+        id = std::move(location->id_);
+        title = std::move(location->title_);
+        description = to_string(location->location_->latitude_) + " " + to_string(location->location_->longitude_);
+        thumbnail_url = std::move(location->thumbnail_url_);
+        // duration = location->live_period_;
+        if (!thumbnail_url.empty()) {
+          thumbnail_width = location->thumbnail_width_;
+          thumbnail_height = location->thumbnail_height_;
+        }
+
+        r_inline_message =
+            get_inline_message(std::move(location->input_message_content_), std::move(location->reply_markup_), -1);
+        break;
+      }
+      case td_api::inputInlineQueryResultPhoto::ID: {
+        auto photo = move_tl_object_as<td_api::inputInlineQueryResultPhoto>(input_result);
+        type = "photo";
+        id = std::move(photo->id_);
+        title = std::move(photo->title_);
+        description = std::move(photo->description_);
+        thumbnail_url = std::move(photo->thumbnail_url_);
+        content_url = std::move(photo->photo_url_);
+        content_type = "image/jpeg";
+        width = photo->photo_width_;
+        height = photo->photo_height_;
+        is_gallery = true;
+
+        file_type = FileType::Photo;
+        r_inline_message = get_inline_message(std::move(photo->input_message_content_), std::move(photo->reply_markup_),
+                                              td_api::inputMessagePhoto::ID);
+        break;
+      }
+      case td_api::inputInlineQueryResultSticker::ID: {
+        auto sticker = move_tl_object_as<td_api::inputInlineQueryResultSticker>(input_result);
+        type = "sticker";
+        id = std::move(sticker->id_);
+        thumbnail_url = std::move(sticker->thumbnail_url_);
+        content_url = std::move(sticker->sticker_url_);
+        content_type = "image/webp";
+        width = sticker->sticker_width_;
+        height = sticker->sticker_height_;
+        is_gallery = true;
+
+        if (content_url.find('.') != string::npos) {
+          return promise.set_error(Status::Error(400, "Wrong sticker_file_id specified"));
+        }
+
+        file_type = FileType::Sticker;
+        r_inline_message = get_inline_message(std::move(sticker->input_message_content_),
+                                              std::move(sticker->reply_markup_), td_api::inputMessageSticker::ID);
+        break;
+      }
+      case td_api::inputInlineQueryResultVenue::ID: {
+        auto venue = move_tl_object_as<td_api::inputInlineQueryResultVenue>(input_result);
+        type = "venue";
+        id = std::move(venue->id_);
+        title = std::move(venue->venue_->title_);
+        description = std::move(venue->venue_->address_);
+        thumbnail_url = std::move(venue->thumbnail_url_);
+        if (!thumbnail_url.empty()) {
+          thumbnail_width = venue->thumbnail_width_;
+          thumbnail_height = venue->thumbnail_height_;
+        }
+
+        r_inline_message =
+            get_inline_message(std::move(venue->input_message_content_), std::move(venue->reply_markup_), -1);
+        break;
+      }
+      case td_api::inputInlineQueryResultVideo::ID: {
+        auto video = move_tl_object_as<td_api::inputInlineQueryResultVideo>(input_result);
+        type = "video";
+        id = std::move(video->id_);
+        title = std::move(video->title_);
+        description = std::move(video->description_);
+        thumbnail_url = std::move(video->thumbnail_url_);
+        content_url = std::move(video->video_url_);
+        content_type = std::move(video->mime_type_);
+        width = video->video_width_;
+        height = video->video_height_;
+        duration = video->video_duration_;
+
+        if (content_url.find('.') != string::npos) {
+          if (begins_with(content_type, "video/mp4")) {
+            content_type = "video/mp4";
+          } else if (begins_with(content_type, "text/html")) {
+            content_type = "text/html";
+          } else {
+            return promise.set_error(Status::Error(400, "Unallowed video MIME type"));
+          }
+        }
+
+        file_type = FileType::Video;
+        r_inline_message = get_inline_message(std::move(video->input_message_content_), std::move(video->reply_markup_),
+                                              td_api::inputMessageVideo::ID);
+        break;
+      }
+      case td_api::inputInlineQueryResultVoiceNote::ID: {
+        auto voice_note = move_tl_object_as<td_api::inputInlineQueryResultVoiceNote>(input_result);
+        type = "voice";
+        id = std::move(voice_note->id_);
+        title = std::move(voice_note->title_);
+        content_url = std::move(voice_note->voice_note_url_);
+        content_type = "audio/ogg";
+        duration = voice_note->voice_note_duration_;
+        force_vertical = true;
+
+        file_type = FileType::VoiceNote;
+        r_inline_message = get_inline_message(std::move(voice_note->input_message_content_),
+                                              std::move(voice_note->reply_markup_), td_api::inputMessageVoiceNote::ID);
+        break;
+      }
+      default:
+        UNREACHABLE();
+        break;
+    }
+    if (r_inline_message.is_error()) {
+      return promise.set_error(r_inline_message.move_as_error());
+    }
+    auto inline_message = r_inline_message.move_as_ok();
+    if (inline_message->get_id() == telegram_api::inputBotInlineMessageMediaAuto::ID && file_type == FileType::Temp) {
+      return promise.set_error(Status::Error(400, "Sent message content should be explicitly specified"));
+    }
+
+    int32 flags = 0;
+    if (!title.empty()) {
+      flags |= telegram_api::inputBotInlineResult::TITLE_MASK;
+      if (!clean_input_string(title)) {
+        return promise.set_error(Status::Error(400, "Strings must be encoded in UTF-8"));
+      }
+    }
+    if (!description.empty()) {
+      flags |= telegram_api::inputBotInlineResult::DESCRIPTION_MASK;
+      if (!clean_input_string(description)) {
+        return promise.set_error(Status::Error(400, "Strings must be encoded in UTF-8"));
+      }
+    }
+
+    if (file_type != FileType::Temp && content_url.find('.') == string::npos) {
+      auto r_file_id = td_->file_manager_->get_input_file_id(
+          file_type, make_tl_object<td_api::inputFileRemote>(content_url), DialogId(), false, false);
+      if (r_file_id.is_error()) {
+        return promise.set_error(Status::Error(400, r_file_id.error().message()));
+      }
+      auto file_id = r_file_id.ok();
+      FileView file_view = td_->file_manager_->get_file_view(file_id);
+      CHECK(file_view.has_remote_location());
+      if (file_view.is_encrypted()) {
+        return promise.set_error(Status::Error(400, "Can't send encrypted file"));
+      }
+      if (file_view.remote_location().is_web()) {
+        return promise.set_error(Status::Error(400, "Can't send web file"));
+      }
+
+      if (file_type == FileType::Photo) {
+        auto result = make_tl_object<telegram_api::inputBotInlineResultPhoto>(
+            id, type, file_view.remote_location().as_input_photo(), std::move(inline_message));
+        results.push_back(std::move(result));
+        continue;
+      }
+
+      auto result = make_tl_object<telegram_api::inputBotInlineResultDocument>(
+          flags, id, type, title, description, file_view.remote_location().as_input_document(),
+          std::move(inline_message));
+      results.push_back(std::move(result));
+      continue;
+    }
+
+    if (!url.empty()) {
+      flags |= telegram_api::inputBotInlineResult::URL_MASK;
+      if (!clean_input_string(url)) {
+        return promise.set_error(Status::Error(400, "Strings must be encoded in UTF-8"));
+      }
+    }
+    tl_object_ptr<telegram_api::inputWebDocument> thumbnail;
+    if (!thumbnail_url.empty()) {
+      flags |= telegram_api::inputBotInlineResult::THUMB_MASK;
+      if (!clean_input_string(thumbnail_url)) {
+        return promise.set_error(Status::Error(400, "Strings must be encoded in UTF-8"));
+      }
+      vector<tl_object_ptr<telegram_api::DocumentAttribute>> attributes;
+      if (thumbnail_width > 0 && thumbnail_height > 0) {
+        attributes.push_back(
+            make_tl_object<telegram_api::documentAttributeImageSize>(thumbnail_width, thumbnail_height));
+      }
+      thumbnail = make_tl_object<telegram_api::inputWebDocument>(thumbnail_url, 0, "image/jpeg", std::move(attributes));
+    }
+    tl_object_ptr<telegram_api::inputWebDocument> content;
+    if (!content_url.empty() || !content_type.empty()) {
+      flags |= telegram_api::inputBotInlineResult::CONTENT_MASK;
+      if (!clean_input_string(content_url)) {
+        return promise.set_error(Status::Error(400, "Strings must be encoded in UTF-8"));
+      }
+      if (!clean_input_string(content_type)) {
+        return promise.set_error(Status::Error(400, "Strings must be encoded in UTF-8"));
+      }
+
+      vector<tl_object_ptr<telegram_api::DocumentAttribute>> attributes;
+      if (width > 0 && height > 0) {
+        if (duration > 0 && !begins_with(content_type, "image/")) {
+          attributes.push_back(make_tl_object<telegram_api::documentAttributeVideo>(
+              0, false /*ignored*/, false /*ignored*/, duration, width, height));
+        } else {
+          attributes.push_back(make_tl_object<telegram_api::documentAttributeImageSize>(width, height));
+        }
+      } else if (duration > 0) {
+        if (type == "audio") {
+          attributes.push_back(make_tl_object<telegram_api::documentAttributeAudio>(
+              telegram_api::documentAttributeAudio::TITLE_MASK | telegram_api::documentAttributeAudio::PERFORMER_MASK,
+              false /*ignored*/, duration, title, description, BufferSlice()));
+        } else if (type == "voice") {
+          attributes.push_back(make_tl_object<telegram_api::documentAttributeAudio>(
+              telegram_api::documentAttributeAudio::VOICE_MASK, false /*ignored*/, duration, "", "", BufferSlice()));
+        }
+      }
+      attributes.push_back(make_tl_object<telegram_api::documentAttributeFilename>(get_url_file_name(content_url)));
+
+      content = make_tl_object<telegram_api::inputWebDocument>(content_url, 0, content_type, std::move(attributes));
+    }
+
+    auto result = make_tl_object<telegram_api::inputBotInlineResult>(
+        flags, id, type, title, description, url, std::move(thumbnail), std::move(content), std::move(inline_message));
+    results.push_back(std::move(result));
+  }
+
+  td_->create_handler<SetInlineBotResultsQuery>(std::move(promise))
+      ->send(inline_query_id, is_gallery && !force_vertical, is_personal, std::move(results), cache_time, next_offset,
+             switch_pm_text, switch_pm_parameter);
+}
+
+uint64 InlineQueriesManager::send_inline_query(UserId bot_user_id, DialogId dialog_id, Location user_location,
+                                               const string &query, const string &offset, Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    promise.set_error(Status::Error(5, "Bot can't send inline queries to other bot"));
+    return 0;
+  }
+
+  auto r_bot_data = td_->contacts_manager_->get_bot_data(bot_user_id);
+  if (r_bot_data.is_error()) {
+    promise.set_error(r_bot_data.move_as_error());
+    return 0;
+  }
+  if (!r_bot_data.ok().is_inline) {
+    promise.set_error(Status::Error(5, "Bot doesn't support inline queries"));
+    return 0;
+  }
+
+  uint64 query_hash = std::hash<std::string>()(trim(query));
+  query_hash = query_hash * 2023654985u + bot_user_id.get();
+  query_hash = query_hash * 2023654985u + std::hash<std::string>()(offset);
+  if (r_bot_data.ok().need_location) {
+    query_hash = query_hash * 2023654985u + static_cast<uint64>(user_location.get_latitude() * 1e4);
+    query_hash = query_hash * 2023654985u + static_cast<uint64>(user_location.get_longitude() * 1e4);
+  }
+  query_hash &= 0x7FFFFFFFFFFFFFFF;
+
+  auto it = inline_query_results_.find(query_hash);
+  if (it != inline_query_results_.end()) {
+    it->second.pending_request_count++;
+    if (Time::now() < it->second.cache_expire_time) {
+      promise.set_value(Unit());
+      return query_hash;
+    }
+  } else {
+    inline_query_results_[query_hash] = {nullptr, -1.0, 1};
+  }
+
+  if (pending_inline_query_ != nullptr) {
+    LOG(INFO) << "Drop inline query " << pending_inline_query_->query_hash;
+    on_get_inline_query_results(pending_inline_query_->bot_user_id, pending_inline_query_->query_hash, nullptr);
+    pending_inline_query_->promise.set_error(Status::Error(406, "Request cancelled"));
+  }
+
+  pending_inline_query_ = make_unique<PendingInlineQuery>(
+      PendingInlineQuery{query_hash, bot_user_id, dialog_id, user_location, query, offset, std::move(promise)});
+
+  loop();
+
+  return query_hash;
+}
+
+void InlineQueriesManager::loop() {
+  LOG(INFO) << "Inline query loop";
+  if (pending_inline_query_ == nullptr) {
+    return;
+  }
+
+  auto now = Time::now();
+  if (now >= next_inline_query_time_) {
+    LOG(INFO) << "Send inline query " << pending_inline_query_->query_hash;
+    auto bot_input_user = td_->contacts_manager_->get_input_user(pending_inline_query_->bot_user_id);
+    if (bot_input_user != nullptr) {
+      if (!sent_query_.empty()) {
+        LOG(INFO) << "Cancel inline query request";
+        cancel_query(sent_query_);
+      }
+      sent_query_ =
+          td_->create_handler<GetInlineBotResultsQuery>(std::move(pending_inline_query_->promise))
+              ->send(pending_inline_query_->bot_user_id, std::move(bot_input_user), pending_inline_query_->dialog_id,
+                     pending_inline_query_->user_location, pending_inline_query_->query, pending_inline_query_->offset,
+                     pending_inline_query_->query_hash);
+
+      next_inline_query_time_ = now + INLINE_QUERY_DELAY_MS * 1e-3;
+    }
+    pending_inline_query_ = nullptr;
+  } else {
+    if (!has_timeout()) {
+      LOG(INFO) << "Schedule send inline query " << pending_inline_query_->query_hash << " at "
+                << G()->to_server_time(next_inline_query_time_);
+      set_timeout_at(next_inline_query_time_);
+    }
+  }
+}
+
+template <class T>
+static tl_object_ptr<T> copy(const T &obj) {
+  // see https://bugs.llvm.org/show_bug.cgi?id=17537
+  static_assert(sizeof(T) == 0, "Only specializations of <copy> can be used");
+}
+
+template <class T>
+static tl_object_ptr<T> copy(const tl_object_ptr<T> &obj) {
+  return obj == nullptr ? nullptr : copy(*obj);
+}
+
+template <>
+td_api::object_ptr<td_api::localFile> copy(const td_api::localFile &obj) {
+  return td_api::make_object<td_api::localFile>(obj.path_, obj.can_be_downloaded_, obj.can_be_deleted_,
+                                                obj.is_downloading_active_, obj.is_downloading_completed_,
+                                                obj.downloaded_prefix_size_, obj.downloaded_size_);
+}
+template <>
+td_api::object_ptr<td_api::remoteFile> copy(const td_api::remoteFile &obj) {
+  return td_api::make_object<td_api::remoteFile>(obj.id_, obj.is_uploading_active_, obj.is_uploading_completed_,
+                                                 obj.uploaded_size_);
+}
+
+template <>
+td_api::object_ptr<td_api::file> copy(const td_api::file &obj) {
+  FileId file_id(obj.id_, 0);  // wrong, but there should be no difference for get_file_object
+  if (file_id.is_valid()) {
+    return G()->td().get_actor_unsafe()->file_manager_.get()->get_file_object(file_id);
+  } else {
+    return td_api::make_object<td_api::file>(obj.id_, obj.size_, obj.expected_size_, copy(obj.local_),
+                                             copy(obj.remote_));
+  }
+}
+
+template <>
+tl_object_ptr<td_api::photoSize> copy(const td_api::photoSize &obj) {
+  return make_tl_object<td_api::photoSize>(obj.type_, copy(obj.photo_), obj.width_, obj.height_);
+}
+
+static tl_object_ptr<td_api::photoSize> copy_photo_size(const tl_object_ptr<td_api::photoSize> &obj) {
+  return copy(obj);
+}
+
+template <>
+tl_object_ptr<td_api::MaskPoint> copy(const td_api::MaskPoint &obj) {
+  switch (obj.get_id()) {
+    case td_api::maskPointForehead::ID:
+      return make_tl_object<td_api::maskPointForehead>();
+    case td_api::maskPointEyes::ID:
+      return make_tl_object<td_api::maskPointEyes>();
+    case td_api::maskPointMouth::ID:
+      return make_tl_object<td_api::maskPointMouth>();
+    case td_api::maskPointChin::ID:
+      return make_tl_object<td_api::maskPointChin>();
+    default:
+      UNREACHABLE();
+  }
+  return nullptr;
+}
+
+template <>
+tl_object_ptr<td_api::maskPosition> copy(const td_api::maskPosition &obj) {
+  return make_tl_object<td_api::maskPosition>(copy(obj.point_), obj.x_shift_, obj.y_shift_, obj.scale_);
+}
+
+template <>
+tl_object_ptr<td_api::animation> copy(const td_api::animation &obj) {
+  return make_tl_object<td_api::animation>(obj.duration_, obj.width_, obj.height_, obj.file_name_, obj.mime_type_,
+                                           copy(obj.thumbnail_), copy(obj.animation_));
+}
+
+template <>
+tl_object_ptr<td_api::audio> copy(const td_api::audio &obj) {
+  return make_tl_object<td_api::audio>(obj.duration_, obj.title_, obj.performer_, obj.file_name_, obj.mime_type_,
+                                       copy(obj.album_cover_thumbnail_), copy(obj.audio_));
+}
+
+template <>
+tl_object_ptr<td_api::document> copy(const td_api::document &obj) {
+  return make_tl_object<td_api::document>(obj.file_name_, obj.mime_type_, copy(obj.thumbnail_), copy(obj.document_));
+}
+
+template <>
+tl_object_ptr<td_api::photo> copy(const td_api::photo &obj) {
+  return make_tl_object<td_api::photo>(obj.id_, obj.has_stickers_, transform(obj.sizes_, copy_photo_size));
+}
+
+template <>
+tl_object_ptr<td_api::sticker> copy(const td_api::sticker &obj) {
+  return make_tl_object<td_api::sticker>(obj.set_id_, obj.width_, obj.height_, obj.emoji_, obj.is_mask_,
+                                         copy(obj.mask_position_), copy(obj.thumbnail_), copy(obj.sticker_));
+}
+
+template <>
+tl_object_ptr<td_api::video> copy(const td_api::video &obj) {
+  return make_tl_object<td_api::video>(obj.duration_, obj.width_, obj.height_, obj.file_name_, obj.mime_type_,
+                                       obj.has_stickers_, obj.supports_streaming_, copy(obj.thumbnail_),
+                                       copy(obj.video_));
+}
+
+template <>
+tl_object_ptr<td_api::voiceNote> copy(const td_api::voiceNote &obj) {
+  return make_tl_object<td_api::voiceNote>(obj.duration_, obj.waveform_, obj.mime_type_, copy(obj.voice_));
+}
+
+template <>
+tl_object_ptr<td_api::contact> copy(const td_api::contact &obj) {
+  return make_tl_object<td_api::contact>(obj.phone_number_, obj.first_name_, obj.last_name_, obj.user_id_);
+}
+
+template <>
+tl_object_ptr<td_api::location> copy(const td_api::location &obj) {
+  return make_tl_object<td_api::location>(obj.latitude_, obj.longitude_);
+}
+
+template <>
+tl_object_ptr<td_api::venue> copy(const td_api::venue &obj) {
+  return make_tl_object<td_api::venue>(copy(obj.location_), obj.title_, obj.address_, obj.provider_, obj.id_);
+}
+
+template <>
+tl_object_ptr<td_api::formattedText> copy(const td_api::formattedText &obj) {
+  // there is no entities in the game text
+  return make_tl_object<td_api::formattedText>(obj.text_, vector<tl_object_ptr<td_api::textEntity>>());
+}
+
+template <>
+tl_object_ptr<td_api::game> copy(const td_api::game &obj) {
+  return make_tl_object<td_api::game>(obj.id_, obj.short_name_, obj.title_, copy(obj.text_), obj.description_,
+                                      copy(obj.photo_), copy(obj.animation_));
+}
+
+template <>
+tl_object_ptr<td_api::inlineQueryResultArticle> copy(const td_api::inlineQueryResultArticle &obj) {
+  return make_tl_object<td_api::inlineQueryResultArticle>(obj.id_, obj.url_, obj.hide_url_, obj.title_,
+                                                          obj.description_, copy(obj.thumbnail_));
+}
+
+template <>
+tl_object_ptr<td_api::inlineQueryResultContact> copy(const td_api::inlineQueryResultContact &obj) {
+  return make_tl_object<td_api::inlineQueryResultContact>(obj.id_, copy(obj.contact_), copy(obj.thumbnail_));
+}
+
+template <>
+tl_object_ptr<td_api::inlineQueryResultLocation> copy(const td_api::inlineQueryResultLocation &obj) {
+  return make_tl_object<td_api::inlineQueryResultLocation>(obj.id_, copy(obj.location_), obj.title_,
+                                                           copy(obj.thumbnail_));
+}
+
+template <>
+tl_object_ptr<td_api::inlineQueryResultVenue> copy(const td_api::inlineQueryResultVenue &obj) {
+  return make_tl_object<td_api::inlineQueryResultVenue>(obj.id_, copy(obj.venue_), copy(obj.thumbnail_));
+}
+
+template <>
+tl_object_ptr<td_api::inlineQueryResultGame> copy(const td_api::inlineQueryResultGame &obj) {
+  return make_tl_object<td_api::inlineQueryResultGame>(obj.id_, copy(obj.game_));
+}
+
+template <>
+tl_object_ptr<td_api::inlineQueryResultAnimation> copy(const td_api::inlineQueryResultAnimation &obj) {
+  return make_tl_object<td_api::inlineQueryResultAnimation>(obj.id_, copy(obj.animation_), obj.title_);
+}
+
+template <>
+tl_object_ptr<td_api::inlineQueryResultAudio> copy(const td_api::inlineQueryResultAudio &obj) {
+  return make_tl_object<td_api::inlineQueryResultAudio>(obj.id_, copy(obj.audio_));
+}
+
+template <>
+tl_object_ptr<td_api::inlineQueryResultDocument> copy(const td_api::inlineQueryResultDocument &obj) {
+  return make_tl_object<td_api::inlineQueryResultDocument>(obj.id_, copy(obj.document_), obj.title_, obj.description_);
+}
+
+template <>
+tl_object_ptr<td_api::inlineQueryResultPhoto> copy(const td_api::inlineQueryResultPhoto &obj) {
+  return make_tl_object<td_api::inlineQueryResultPhoto>(obj.id_, copy(obj.photo_), obj.title_, obj.description_);
+}
+
+template <>
+tl_object_ptr<td_api::inlineQueryResultSticker> copy(const td_api::inlineQueryResultSticker &obj) {
+  return make_tl_object<td_api::inlineQueryResultSticker>(obj.id_, copy(obj.sticker_));
+}
+
+template <>
+tl_object_ptr<td_api::inlineQueryResultVideo> copy(const td_api::inlineQueryResultVideo &obj) {
+  return make_tl_object<td_api::inlineQueryResultVideo>(obj.id_, copy(obj.video_), obj.title_, obj.description_);
+}
+
+template <>
+tl_object_ptr<td_api::inlineQueryResultVoiceNote> copy(const td_api::inlineQueryResultVoiceNote &obj) {
+  return make_tl_object<td_api::inlineQueryResultVoiceNote>(obj.id_, copy(obj.voice_note_), obj.title_);
+}
+
+static tl_object_ptr<td_api::InlineQueryResult> copy_result(const tl_object_ptr<td_api::InlineQueryResult> &obj_ptr) {
+  tl_object_ptr<td_api::InlineQueryResult> result;
+  downcast_call(*obj_ptr, [&result](const auto &obj) { result = copy(obj); });
+  return result;
+}
+
+template <>
+tl_object_ptr<td_api::inlineQueryResults> copy(const td_api::inlineQueryResults &obj) {
+  return make_tl_object<td_api::inlineQueryResults>(obj.inline_query_id_, obj.next_offset_,
+                                                    transform(obj.results_, copy_result), obj.switch_pm_text_,
+                                                    obj.switch_pm_parameter_);
+}
+
+tl_object_ptr<td_api::inlineQueryResults> InlineQueriesManager::decrease_pending_request_count(uint64 query_hash) {
+  auto it = inline_query_results_.find(query_hash);
+  CHECK(it != inline_query_results_.end());
+  CHECK(it->second.pending_request_count > 0);
+  it->second.pending_request_count--;
+  LOG(INFO) << "Inline query " << query_hash << " is awaited by " << it->second.pending_request_count
+            << " pending requests";
+  if (it->second.pending_request_count == 0) {
+    auto left_time = it->second.cache_expire_time - Time::now();
+    if (left_time < 0) {
+      LOG(INFO) << "Drop cache for inline query " << query_hash;
+      auto result = std::move(it->second.results);
+      inline_query_results_.erase(it);
+      return result;
+    } else {
+      drop_inline_query_result_timeout_.set_timeout_at(static_cast<int64>(query_hash), it->second.cache_expire_time);
+    }
+  }
+  return copy(it->second.results);
+}
+
+tl_object_ptr<td_api::photoSize> InlineQueriesManager::register_thumbnail(
+    tl_object_ptr<telegram_api::WebDocument> &&web_document_ptr) const {
+  PhotoSize thumbnail = get_web_document_photo_size(td_->file_manager_.get(), FileType::Thumbnail, DialogId(),
+                                                    std::move(web_document_ptr));
+  if (!thumbnail.file_id.is_valid()) {
+    return nullptr;
+  }
+
+  return get_photo_size_object(td_->file_manager_.get(), &thumbnail);
+}
+
+string InlineQueriesManager::get_web_document_url(const tl_object_ptr<telegram_api::WebDocument> &web_document_ptr) {
+  if (web_document_ptr == nullptr) {
+    return {};
+  }
+
+  string url;
+  switch (web_document_ptr->get_id()) {
+    case telegram_api::webDocument::ID: {
+      auto web_document = static_cast<const telegram_api::webDocument *>(web_document_ptr.get());
+      url = web_document->url_;
+      break;
+    }
+    case telegram_api::webDocumentNoProxy::ID: {
+      auto web_document = static_cast<const telegram_api::webDocumentNoProxy *>(web_document_ptr.get());
+      url = web_document->url_;
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+
+  auto r_http_url = parse_url(url);
+  if (r_http_url.is_error()) {
+    LOG(ERROR) << "Can't parse URL " << url;
+    return {};
+  }
+  return r_http_url.ok().get_url();
+}
+
+string InlineQueriesManager::get_web_document_content_type(
+    const tl_object_ptr<telegram_api::WebDocument> &web_document_ptr) {
+  if (web_document_ptr == nullptr) {
+    return {};
+  }
+
+  switch (web_document_ptr->get_id()) {
+    case telegram_api::webDocument::ID:
+      return static_cast<const telegram_api::webDocument *>(web_document_ptr.get())->mime_type_;
+    case telegram_api::webDocumentNoProxy::ID:
+      return static_cast<const telegram_api::webDocumentNoProxy *>(web_document_ptr.get())->mime_type_;
+    default:
+      UNREACHABLE();
+  }
+
+  return {};
+}
+
+void InlineQueriesManager::on_get_inline_query_results(UserId bot_user_id, uint64 query_hash,
+                                                       tl_object_ptr<telegram_api::messages_botResults> &&results) {
+  LOG(INFO) << "Receive results for inline query " << query_hash;
+  if (results == nullptr) {
+    decrease_pending_request_count(query_hash);
+    return;
+  }
+  LOG(INFO) << to_string(results);
+
+  td_->contacts_manager_->on_get_users(std::move(results->users_));
+
+  vector<tl_object_ptr<td_api::InlineQueryResult>> output_results;
+  for (auto &result_ptr : results->results_) {
+    tl_object_ptr<td_api::InlineQueryResult> output_result;
+    switch (result_ptr->get_id()) {
+      case telegram_api::botInlineMediaResult::ID: {
+        auto result = move_tl_object_as<telegram_api::botInlineMediaResult>(result_ptr);
+        auto flags = result->flags_;
+        bool has_document = (flags & BOT_INLINE_MEDIA_RESULT_FLAG_HAS_DOCUMENT) != 0;
+        bool has_photo = (flags & BOT_INLINE_MEDIA_RESULT_FLAG_HAS_PHOTO) != 0;
+        bool is_photo = result->type_ == "photo";
+        if (result->type_ == "game") {
+          auto game = make_tl_object<td_api::inlineQueryResultGame>();
+          Game inline_game(td_, std::move(result->title_), std::move(result->description_), std::move(result->photo_),
+                           std::move(result->document_), DialogId());
+
+          game->id_ = std::move(result->id_);
+          game->game_ = inline_game.get_game_object(td_);
+
+          if (!register_inline_message_content(results->query_id_, game->id_, FileId(),
+                                               std::move(result->send_message_), td_api::inputMessageGame::ID, nullptr,
+                                               &inline_game)) {
+            continue;
+          }
+          output_result = std::move(game);
+        } else if (has_document && !(has_photo && is_photo)) {
+          auto document_ptr = std::move(result->document_);
+          int32 document_id = document_ptr->get_id();
+          if (document_id == telegram_api::documentEmpty::ID) {
+            LOG(ERROR) << "Receive empty cached document in the result of inline query";
+            break;
+          }
+          CHECK(document_id == telegram_api::document::ID);
+
+          auto parsed_document = td_->documents_manager_->on_get_document(
+              move_tl_object_as<telegram_api::document>(document_ptr), DialogId());
+          switch (parsed_document.first) {
+            case DocumentsManager::DocumentType::Animation: {
+              LOG_IF(WARNING, result->type_ != "gif") << "Wrong result type " << result->type_;
+
+              auto animation = make_tl_object<td_api::inlineQueryResultAnimation>();
+              animation->id_ = std::move(result->id_);
+              animation->animation_ =
+                  td_->animations_manager_->get_animation_object(parsed_document.second, "inlineQueryResultAnimation");
+              animation->title_ = std::move(result->title_);
+
+              if (!register_inline_message_content(results->query_id_, animation->id_, parsed_document.second,
+                                                   std::move(result->send_message_),
+                                                   td_api::inputMessageAnimation::ID)) {
+                continue;
+              }
+              output_result = std::move(animation);
+              break;
+            }
+            case DocumentsManager::DocumentType::Audio: {
+              LOG_IF(WARNING, result->type_ != "audio") << "Wrong result type " << result->type_;
+
+              auto audio = make_tl_object<td_api::inlineQueryResultAudio>();
+              audio->id_ = std::move(result->id_);
+              audio->audio_ = td_->audios_manager_->get_audio_object(parsed_document.second);
+
+              if (!register_inline_message_content(results->query_id_, audio->id_, parsed_document.second,
+                                                   std::move(result->send_message_), td_api::inputMessageAudio::ID)) {
+                continue;
+              }
+              output_result = std::move(audio);
+              break;
+            }
+            case DocumentsManager::DocumentType::General: {
+              LOG_IF(WARNING, result->type_ != "file") << "Wrong result type " << result->type_;
+
+              auto document = make_tl_object<td_api::inlineQueryResultDocument>();
+              document->id_ = std::move(result->id_);
+              document->document_ = td_->documents_manager_->get_document_object(parsed_document.second);
+              document->title_ = std::move(result->title_);
+              document->description_ = std::move(result->description_);
+
+              if (!register_inline_message_content(results->query_id_, document->id_, parsed_document.second,
+                                                   std::move(result->send_message_),
+                                                   td_api::inputMessageDocument::ID)) {
+                continue;
+              }
+              output_result = std::move(document);
+              break;
+            }
+            case DocumentsManager::DocumentType::Sticker: {
+              LOG_IF(WARNING, result->type_ != "sticker") << "Wrong result type " << result->type_;
+
+              auto sticker = make_tl_object<td_api::inlineQueryResultSticker>();
+              sticker->id_ = std::move(result->id_);
+              sticker->sticker_ = td_->stickers_manager_->get_sticker_object(parsed_document.second);
+
+              if (!register_inline_message_content(results->query_id_, sticker->id_, parsed_document.second,
+                                                   std::move(result->send_message_), td_api::inputMessageSticker::ID)) {
+                continue;
+              }
+              output_result = std::move(sticker);
+              break;
+            }
+            case DocumentsManager::DocumentType::Video: {
+              LOG_IF(WARNING, result->type_ != "video") << "Wrong result type " << result->type_;
+
+              auto video = make_tl_object<td_api::inlineQueryResultVideo>();
+              video->id_ = std::move(result->id_);
+              video->video_ = td_->videos_manager_->get_video_object(parsed_document.second);
+              video->title_ = std::move(result->title_);
+              video->description_ = std::move(result->description_);
+
+              if (!register_inline_message_content(results->query_id_, video->id_, parsed_document.second,
+                                                   std::move(result->send_message_), td_api::inputMessageVideo::ID)) {
+                continue;
+              }
+              output_result = std::move(video);
+              break;
+            }
+            case DocumentsManager::DocumentType::VideoNote:
+              // FIXME
+              break;
+            case DocumentsManager::DocumentType::VoiceNote: {
+              LOG_IF(WARNING, result->type_ != "voice") << "Wrong result type " << result->type_;
+
+              auto voice_note = make_tl_object<td_api::inlineQueryResultVoiceNote>();
+              voice_note->id_ = std::move(result->id_);
+              voice_note->voice_note_ = td_->voice_notes_manager_->get_voice_note_object(parsed_document.second);
+              voice_note->title_ = std::move(result->title_);
+
+              if (!register_inline_message_content(results->query_id_, voice_note->id_, parsed_document.second,
+                                                   std::move(result->send_message_),
+                                                   td_api::inputMessageVoiceNote::ID)) {
+                continue;
+              }
+              output_result = std::move(voice_note);
+              break;
+            }
+            case DocumentsManager::DocumentType::Unknown:
+              // invalid document
+              break;
+            default:
+              UNREACHABLE();
+              break;
+          }
+        } else if (has_photo) {
+          LOG_IF(ERROR, !is_photo) << "Wrong result type " << result->type_;
+          auto photo = make_tl_object<td_api::inlineQueryResultPhoto>();
+          photo->id_ = std::move(result->id_);
+          auto photo_ptr = std::move(result->photo_);
+          int32 photo_id = photo_ptr->get_id();
+          if (photo_id == telegram_api::photoEmpty::ID) {
+            LOG(ERROR) << "Receive empty cached photo in the result of inline query";
+            break;
+          }
+          CHECK(photo_id == telegram_api::photo::ID);
+
+          Photo p = get_photo(td_->file_manager_.get(), move_tl_object_as<telegram_api::photo>(photo_ptr), DialogId());
+          photo->photo_ = get_photo_object(td_->file_manager_.get(), &p);
+          photo->title_ = std::move(result->title_);
+          photo->description_ = std::move(result->description_);
+
+          if (!register_inline_message_content(results->query_id_, photo->id_, FileId(),
+                                               std::move(result->send_message_), td_api::inputMessagePhoto::ID, &p)) {
+            continue;
+          }
+          output_result = std::move(photo);
+        } else {
+          LOG(ERROR) << "Receive inline query media result without photo and document: " << to_string(result);
+        }
+        break;
+      }
+      case telegram_api::botInlineResult::ID: {
+        auto result = move_tl_object_as<telegram_api::botInlineResult>(result_ptr);
+        auto content_type = get_web_document_content_type(result->content_);
+        if (result->type_ == "article") {
+          auto article = make_tl_object<td_api::inlineQueryResultArticle>();
+          article->id_ = std::move(result->id_);
+          article->url_ = get_web_document_url(std::move(result->content_));
+          if (result->url_.empty()) {
+            article->hide_url_ = true;
+          } else {
+            LOG_IF(ERROR, result->url_ != article->url_)
+                << "Url has changed from " << article->url_ << " to " << result->url_;
+            article->hide_url_ = false;
+          }
+          article->title_ = std::move(result->title_);
+          article->description_ = std::move(result->description_);
+          article->thumbnail_ = register_thumbnail(std::move(result->thumb_));
+
+          if (!register_inline_message_content(results->query_id_, article->id_, FileId(),
+                                               std::move(result->send_message_), -1)) {
+            continue;
+          }
+          output_result = std::move(article);
+        } else if (result->type_ == "contact") {
+          auto contact = make_tl_object<td_api::inlineQueryResultContact>();
+          contact->id_ = std::move(result->id_);
+          if (result->send_message_->get_id() == telegram_api::botInlineMessageMediaContact::ID) {
+            auto inline_message_contact =
+                static_cast<const telegram_api::botInlineMessageMediaContact *>(result->send_message_.get());
+            Contact c(inline_message_contact->phone_number_, inline_message_contact->first_name_,
+                      inline_message_contact->last_name_, 0);
+            contact->contact_ = c.get_contact_object();
+          } else {
+            Contact c(std::move(result->description_), std::move(result->title_), string(), 0);
+            contact->contact_ = c.get_contact_object();
+          }
+          contact->thumbnail_ = register_thumbnail(std::move(result->thumb_));
+
+          if (!register_inline_message_content(results->query_id_, contact->id_, FileId(),
+                                               std::move(result->send_message_), -1)) {
+            continue;
+          }
+          output_result = std::move(contact);
+        } else if (result->type_ == "geo") {
+          auto location = make_tl_object<td_api::inlineQueryResultLocation>();
+          location->id_ = std::move(result->id_);
+          location->title_ = std::move(result->title_);
+          if (result->send_message_->get_id() == telegram_api::botInlineMessageMediaGeo::ID) {
+            auto inline_message_geo =
+                static_cast<const telegram_api::botInlineMessageMediaGeo *>(result->send_message_.get());
+            Location l(inline_message_geo->geo_);
+            location->location_ = l.get_location_object();
+          } else {
+            auto coordinates = split(Slice(result->description_));
+            Location l(to_double(coordinates.first), to_double(coordinates.second));
+            location->location_ = l.get_location_object();
+          }
+          location->thumbnail_ = register_thumbnail(std::move(result->thumb_));
+
+          if (!register_inline_message_content(results->query_id_, location->id_, FileId(),
+                                               std::move(result->send_message_), -1)) {
+            continue;
+          }
+          output_result = std::move(location);
+        } else if (result->type_ == "venue") {
+          auto venue = make_tl_object<td_api::inlineQueryResultVenue>();
+          venue->id_ = std::move(result->id_);
+          if (result->send_message_->get_id() == telegram_api::botInlineMessageMediaVenue::ID) {
+            auto inline_message_venue =
+                static_cast<const telegram_api::botInlineMessageMediaVenue *>(result->send_message_.get());
+            Venue v(inline_message_venue->geo_, inline_message_venue->title_, inline_message_venue->address_,
+                    inline_message_venue->provider_, inline_message_venue->venue_id_);
+            venue->venue_ = v.get_venue_object();
+          } else if (result->send_message_->get_id() == telegram_api::botInlineMessageMediaGeo::ID) {
+            auto inline_message_geo =
+                static_cast<const telegram_api::botInlineMessageMediaGeo *>(result->send_message_.get());
+            Venue v(inline_message_geo->geo_, std::move(result->title_), std::move(result->description_), string(),
+                    string());
+            venue->venue_ = v.get_venue_object();
+          } else {
+            Venue v(nullptr, std::move(result->title_), std::move(result->description_), string(), string());
+            venue->venue_ = v.get_venue_object();
+          }
+          venue->thumbnail_ = register_thumbnail(std::move(result->thumb_));
+
+          if (!register_inline_message_content(results->query_id_, venue->id_, FileId(),
+                                               std::move(result->send_message_), -1)) {
+            continue;
+          }
+          output_result = std::move(venue);
+        } else if (result->type_ == "photo" && content_type == "image/jpeg") {
+          auto photo = make_tl_object<td_api::inlineQueryResultPhoto>();
+          photo->id_ = std::move(result->id_);
+
+          PhotoSize photo_size = get_web_document_photo_size(td_->file_manager_.get(), FileType::Temp, DialogId(),
+                                                             std::move(result->content_));
+          if (!photo_size.file_id.is_valid()) {
+            LOG(ERROR) << "Receive invalid web document photo";
+            continue;
+          }
+
+          Photo new_photo;
+          PhotoSize thumbnail = get_web_document_photo_size(td_->file_manager_.get(), FileType::Thumbnail, DialogId(),
+                                                            std::move(result->thumb_));
+          if (thumbnail.file_id.is_valid()) {
+            new_photo.photos.push_back(std::move(thumbnail));
+          }
+          new_photo.photos.push_back(std::move(photo_size));
+
+          photo->photo_ = get_photo_object(td_->file_manager_.get(), &new_photo);
+          photo->title_ = std::move(result->title_);
+          photo->description_ = std::move(result->description_);
+
+          if (!register_inline_message_content(results->query_id_, photo->id_, FileId(),
+                                               std::move(result->send_message_), td_api::inputMessagePhoto::ID,
+                                               &new_photo)) {
+            continue;
+          }
+          output_result = std::move(photo);
+        } else {
+          if (result->content_ == nullptr) {
+            LOG(ERROR) << "Unsupported inline query result without content " << to_string(result);
+            continue;
+          }
+
+          vector<tl_object_ptr<telegram_api::DocumentAttribute>> attributes;
+          downcast_call(*result->content_,
+                        [&attributes](auto &web_document) { attributes = std::move(web_document.attributes_); });
+
+          bool is_animation = result->type_ == "gif" && (content_type == "image/gif" || content_type == "video/mp4");
+          if (is_animation) {
+            attributes.push_back(make_tl_object<telegram_api::documentAttributeAnimated>());
+          }
+          auto default_document_type = [type = result->type_, is_animation] {
+            if (type == "audio") {
+              return DocumentsManager::DocumentType::Audio;
+            }
+            if (is_animation) {
+              return DocumentsManager::DocumentType::Animation;
+            }
+            if (type == "sticker") {
+              return DocumentsManager::DocumentType::Sticker;
+            }
+            if (type == "video") {
+              return DocumentsManager::DocumentType::Video;
+            }
+            if (type == "voice") {
+              return DocumentsManager::DocumentType::VoiceNote;
+            }
+            return DocumentsManager::DocumentType::General;
+          }();
+
+          auto parsed_document = td_->documents_manager_->on_get_document(
+              {std::move(result->content_),
+               get_web_document_photo_size(td_->file_manager_.get(), FileType::Thumbnail, DialogId(),
+                                           std::move(result->thumb_)),
+               std::move(attributes)},
+              DialogId(), nullptr, default_document_type);
+          auto file_id = parsed_document.second;
+          if (!file_id.is_valid()) {
+            continue;
+          }
+          if (result->type_ == "audio" && parsed_document.first == DocumentsManager::DocumentType::Audio) {
+            auto audio = make_tl_object<td_api::inlineQueryResultAudio>();
+            audio->id_ = std::move(result->id_);
+            audio->audio_ = td_->audios_manager_->get_audio_object(file_id);
+            if (!register_inline_message_content(results->query_id_, audio->id_, file_id,
+                                                 std::move(result->send_message_), td_api::inputMessageAudio::ID)) {
+              continue;
+            }
+            output_result = std::move(audio);
+          } else if (result->type_ == "file" && parsed_document.first == DocumentsManager::DocumentType::General) {
+            auto document = make_tl_object<td_api::inlineQueryResultDocument>();
+            document->id_ = std::move(result->id_);
+            document->document_ = td_->documents_manager_->get_document_object(file_id);
+            document->title_ = std::move(result->title_);
+            document->description_ = std::move(result->description_);
+            if (!register_inline_message_content(results->query_id_, document->id_, file_id,
+                                                 std::move(result->send_message_), td_api::inputMessageDocument::ID)) {
+              continue;
+            }
+            output_result = std::move(document);
+          } else if (is_animation && parsed_document.first == DocumentsManager::DocumentType::Animation) {
+            auto animation = make_tl_object<td_api::inlineQueryResultAnimation>();
+            animation->id_ = std::move(result->id_);
+            animation->animation_ =
+                td_->animations_manager_->get_animation_object(file_id, "inlineQueryResultAnimationCached");
+            animation->title_ = std::move(result->title_);
+            if (!register_inline_message_content(results->query_id_, animation->id_, file_id,
+                                                 std::move(result->send_message_), td_api::inputMessageAnimation::ID)) {
+              continue;
+            }
+            output_result = std::move(animation);
+          } else if (result->type_ == "sticker" && parsed_document.first == DocumentsManager::DocumentType::Sticker) {
+            auto sticker = make_tl_object<td_api::inlineQueryResultSticker>();
+            sticker->id_ = std::move(result->id_);
+            sticker->sticker_ = td_->stickers_manager_->get_sticker_object(file_id);
+            if (!register_inline_message_content(results->query_id_, sticker->id_, file_id,
+                                                 std::move(result->send_message_), td_api::inputMessageSticker::ID)) {
+              continue;
+            }
+            output_result = std::move(sticker);
+          } else if (result->type_ == "video" && parsed_document.first == DocumentsManager::DocumentType::Video) {
+            auto video = make_tl_object<td_api::inlineQueryResultVideo>();
+            video->id_ = std::move(result->id_);
+            video->video_ = td_->videos_manager_->get_video_object(file_id);
+            video->title_ = std::move(result->title_);
+            video->description_ = std::move(result->description_);
+            if (!register_inline_message_content(results->query_id_, video->id_, file_id,
+                                                 std::move(result->send_message_), td_api::inputMessageVideo::ID)) {
+              continue;
+            }
+            output_result = std::move(video);
+          } else if (result->type_ == "voice" && parsed_document.first == DocumentsManager::DocumentType::VoiceNote) {
+            auto voice_note = make_tl_object<td_api::inlineQueryResultVoiceNote>();
+            voice_note->id_ = std::move(result->id_);
+            voice_note->voice_note_ = td_->voice_notes_manager_->get_voice_note_object(file_id);
+            voice_note->title_ = std::move(result->title_);
+            if (!register_inline_message_content(results->query_id_, voice_note->id_, file_id,
+                                                 std::move(result->send_message_), td_api::inputMessageVoiceNote::ID)) {
+              continue;
+            }
+            output_result = std::move(voice_note);
+          } else {
+            LOG(WARNING) << "Unsupported inline query result " << to_string(result);
+          }
+        }
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+    if (output_result != nullptr) {
+      output_results.push_back(std::move(output_result));
+    }
+  }
+
+  auto it = inline_query_results_.find(query_hash);
+  CHECK(it != inline_query_results_.end());
+
+  query_id_to_bot_user_id_[results->query_id_] = bot_user_id;
+
+  string switch_pm_text;
+  string switch_pm_parameter;
+  if (results->switch_pm_ != nullptr) {
+    switch_pm_text = std::move(results->switch_pm_->text_);
+    switch_pm_parameter = std::move(results->switch_pm_->start_param_);
+  }
+
+  it->second.results = make_tl_object<td_api::inlineQueryResults>(
+      results->query_id_, results->next_offset_, std::move(output_results), switch_pm_text, switch_pm_parameter);
+  it->second.cache_expire_time = Time::now() + results->cache_time_;
+}
+
+vector<UserId> InlineQueriesManager::get_recent_inline_bots(Promise<Unit> &&promise) {
+  if (!load_recently_used_bots(promise)) {
+    return vector<UserId>();
+  }
+
+  promise.set_value(Unit());
+  return recently_used_bot_user_ids_;
+}
+
+void InlineQueriesManager::save_recently_used_bots() {
+  if (recently_used_bots_loaded_ < 2) {
+    return;
+  }
+
+  string value;
+  string value_ids;
+  for (auto &bot_user_id : recently_used_bot_user_ids_) {
+    if (!value.empty()) {
+      value += ',';
+      value_ids += ',';
+    }
+    value += td_->contacts_manager_->get_user_username(bot_user_id);
+    value_ids += to_string(bot_user_id.get());
+  }
+  G()->td_db()->get_binlog_pmc()->set("recently_used_inline_bot_usernames", value);
+  G()->td_db()->get_binlog_pmc()->set("recently_used_inline_bots", value_ids);
+}
+
+bool InlineQueriesManager::load_recently_used_bots(Promise<Unit> &promise) {
+  if (recently_used_bots_loaded_ >= 2) {
+    return true;
+  }
+
+  string saved_bot_ids = G()->td_db()->get_binlog_pmc()->get("recently_used_inline_bots");
+  auto bot_ids = full_split(saved_bot_ids, ',');
+  string saved_bots = G()->td_db()->get_binlog_pmc()->get("recently_used_inline_bot_usernames");
+  auto bot_usernames = full_split(saved_bots, ',');
+  if (bot_ids.empty() && bot_usernames.empty()) {
+    recently_used_bots_loaded_ = 2;
+    if (!recently_used_bot_user_ids_.empty()) {
+      save_recently_used_bots();
+    }
+    return true;
+  }
+
+  if (recently_used_bots_loaded_ == 1 && resolve_recent_inline_bots_multipromise_.promise_count() == 0) {
+    // queries was sent and have already been finished
+    auto newly_used_bots = std::move(recently_used_bot_user_ids_);
+    recently_used_bot_user_ids_.clear();
+
+    if (bot_ids.empty()) {
+      // legacy, can be removed in the future
+      for (auto it = bot_usernames.rbegin(); it != bot_usernames.rend(); ++it) {
+        auto dialog_id = td_->messages_manager_->resolve_dialog_username(*it);
+        if (dialog_id.get_type() == DialogType::User) {
+          update_bot_usage(dialog_id.get_user_id());
+        }
+      }
+    } else {
+      for (auto it = bot_ids.rbegin(); it != bot_ids.rend(); ++it) {
+        UserId user_id(to_integer<int32>(*it));
+        if (td_->contacts_manager_->have_user(user_id)) {
+          update_bot_usage(user_id);
+        } else {
+          LOG(ERROR) << "Can't find " << user_id;
+        }
+      }
+    }
+    for (auto it = newly_used_bots.rbegin(); it != newly_used_bots.rend(); ++it) {
+      update_bot_usage(*it);
+    }
+    recently_used_bots_loaded_ = 2;
+    if (!newly_used_bots.empty() || (bot_ids.empty() && !bot_usernames.empty())) {
+      save_recently_used_bots();
+    }
+    return true;
+  }
+
+  resolve_recent_inline_bots_multipromise_.add_promise(std::move(promise));
+  if (recently_used_bots_loaded_ == 0) {
+    resolve_recent_inline_bots_multipromise_.set_ignore_errors(true);
+    if (bot_ids.empty() || !G()->parameters().use_chat_info_db) {
+      for (auto &bot_username : bot_usernames) {
+        td_->messages_manager_->search_public_dialog(bot_username, false,
+                                                     resolve_recent_inline_bots_multipromise_.get_promise());
+      }
+    } else {
+      for (auto &bot_id : bot_ids) {
+        UserId user_id(to_integer<int32>(bot_id));
+        td_->contacts_manager_->get_user(user_id, 3, resolve_recent_inline_bots_multipromise_.get_promise());
+      }
+    }
+    recently_used_bots_loaded_ = 1;
+  }
+  return false;
+}
+
+tl_object_ptr<td_api::inlineQueryResults> InlineQueriesManager::get_inline_query_results_object(uint64 query_hash) {
+  // TODO filter out games if request is sent in a broadcast channel or in a secret chat
+  return decrease_pending_request_count(query_hash);
+}
+
+void InlineQueriesManager::on_new_query(int64 query_id, UserId sender_user_id, Location user_location,
+                                        const string &query, const string &offset) {
+  if (!sender_user_id.is_valid()) {
+    LOG(ERROR) << "Receive new inline query from invalid " << sender_user_id;
+    return;
+  }
+  LOG_IF(ERROR, !td_->contacts_manager_->have_user(sender_user_id)) << "Have no info about " << sender_user_id;
+  if (!td_->auth_manager_->is_bot()) {
+    LOG(ERROR) << "Receive new inline query";
+    return;
+  }
+  send_closure(G()->td(), &Td::send_update,
+               make_tl_object<td_api::updateNewInlineQuery>(
+                   query_id, td_->contacts_manager_->get_user_id_object(sender_user_id, "updateNewInlineQuery"),
+                   user_location.get_location_object(), query, offset));
+}
+
+void InlineQueriesManager::on_chosen_result(
+    UserId user_id, Location user_location, const string &query, const string &result_id,
+    tl_object_ptr<telegram_api::inputBotInlineMessageID> &&input_bot_inline_message_id) {
+  if (!user_id.is_valid()) {
+    LOG(ERROR) << "Receive chosen inline query result from invalid " << user_id;
+    return;
+  }
+  LOG_IF(ERROR, !td_->contacts_manager_->have_user(user_id)) << "Have no info about " << user_id;
+  if (!td_->auth_manager_->is_bot()) {
+    LOG(ERROR) << "Receive chosen inline query result";
+    return;
+  }
+  send_closure(G()->td(), &Td::send_update,
+               make_tl_object<td_api::updateNewChosenInlineResult>(
+                   td_->contacts_manager_->get_user_id_object(user_id, "updateNewChosenInlineResult"),
+                   user_location.get_location_object(), query, result_id,
+                   get_inline_message_id(std::move(input_bot_inline_message_id))));
+}
+
+bool InlineQueriesManager::update_bot_usage(UserId bot_user_id) {
+  if (!bot_user_id.is_valid()) {
+    return false;
+  }
+  if (!recently_used_bot_user_ids_.empty() && recently_used_bot_user_ids_[0] == bot_user_id) {
+    return false;
+  }
+  auto r_bot_data = td_->contacts_manager_->get_bot_data(bot_user_id);
+  if (r_bot_data.is_error()) {
+    return false;
+  }
+  if (r_bot_data.ok().username.empty() || !r_bot_data.ok().is_inline) {
+    return false;
+  }
+
+  auto it = std::find(recently_used_bot_user_ids_.begin(), recently_used_bot_user_ids_.end(), bot_user_id);
+  if (it == recently_used_bot_user_ids_.end()) {
+    if (static_cast<int32>(recently_used_bot_user_ids_.size()) == MAX_RECENT_INLINE_BOTS) {
+      CHECK(!recently_used_bot_user_ids_.empty());
+      recently_used_bot_user_ids_.back() = bot_user_id;
+    } else {
+      recently_used_bot_user_ids_.push_back(bot_user_id);
+    }
+    it = recently_used_bot_user_ids_.end() - 1;
+  }
+  std::rotate(recently_used_bot_user_ids_.begin(), it, it + 1);
+  return true;
+}
+
+void InlineQueriesManager::remove_recent_inline_bot(UserId bot_user_id, Promise<Unit> &&promise) {
+  auto it = std::find(recently_used_bot_user_ids_.begin(), recently_used_bot_user_ids_.end(), bot_user_id);
+  if (it != recently_used_bot_user_ids_.end()) {
+    recently_used_bot_user_ids_.erase(it);
+    save_recently_used_bots();
+  }
+  return promise.set_value(Unit());
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/InlineQueriesManager.h b/libs/tdlib/td/td/telegram/InlineQueriesManager.h
new file mode 100644
index 0000000000..97548c41ed
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/InlineQueriesManager.h
@@ -0,0 +1,165 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/MultiPromise.h"
+#include "td/actor/Timeout.h"
+
+#include "td/telegram/DialogId.h"
+#include "td/telegram/files/FileId.h"
+#include "td/telegram/Location.h"
+#include "td/telegram/MessageEntity.h"
+#include "td/telegram/net/NetQuery.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/ReplyMarkup.h"
+#include "td/telegram/UserId.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Status.h"
+
+#include <tuple>
+#include <unordered_map>
+#include <utility>
+
+namespace td {
+
+class Td;
+
+class MessageContent;
+
+class Game;
+
+class InlineQueriesManager : public Actor {
+ public:
+  InlineQueriesManager(Td *td, ActorShared<> parent);
+
+  void after_get_difference();
+
+  void answer_inline_query(int64 inline_query_id, bool is_personal,
+                           vector<tl_object_ptr<td_api::InputInlineQueryResult>> &&input_results, int32 cache_time,
+                           const string &next_offset, const string &switch_pm_text, const string &switch_pm_parameter,
+                           Promise<Unit> &&promise) const;
+
+  uint64 send_inline_query(UserId bot_user_id, DialogId dialog_id, Location user_location, const string &query,
+                           const string &offset, Promise<Unit> &&promise);
+
+  vector<UserId> get_recent_inline_bots(Promise<Unit> &&promise);
+
+  void remove_recent_inline_bot(UserId bot_user_id, Promise<Unit> &&promise);
+
+  std::tuple<const MessageContent *, const ReplyMarkup *, bool> get_inline_message_content(int64 query_id,
+                                                                                           const string &result_id);
+
+  UserId get_inline_bot_user_id(int64 query_id) const;
+
+  void on_get_inline_query_results(UserId bot_user_id, uint64 query_hash,
+                                   tl_object_ptr<telegram_api::messages_botResults> &&results);
+
+  tl_object_ptr<td_api::inlineQueryResults> get_inline_query_results_object(uint64 query_hash);
+
+  void on_new_query(int64 query_id, UserId sender_user_id, Location user_location, const string &query,
+                    const string &offset);
+
+  void on_chosen_result(UserId user_id, Location user_location, const string &query, const string &result_id,
+                        tl_object_ptr<telegram_api::inputBotInlineMessageID> &&input_bot_inline_message_id);
+
+  static tl_object_ptr<telegram_api::inputBotInlineMessageID> get_input_bot_inline_message_id(
+      const string &inline_message_id);
+
+  static string get_inline_message_id(
+      tl_object_ptr<telegram_api::inputBotInlineMessageID> &&input_bot_inline_message_id);
+
+ private:
+  static constexpr int32 MAX_RECENT_INLINE_BOTS = 20;  // some reasonable value
+  static constexpr int32 INLINE_QUERY_DELAY_MS = 400;  // server side limit
+
+  static constexpr int32 BOT_INLINE_MEDIA_RESULT_FLAG_HAS_PHOTO = 1 << 0;
+  static constexpr int32 BOT_INLINE_MEDIA_RESULT_FLAG_HAS_DOCUMENT = 1 << 1;
+  static constexpr int32 BOT_INLINE_MEDIA_RESULT_FLAG_HAS_TITLE = 1 << 2;
+  static constexpr int32 BOT_INLINE_MEDIA_RESULT_FLAG_HAS_DESCRIPTION = 1 << 3;
+
+  Result<FormattedText> process_input_caption(td_api::object_ptr<td_api::formattedText> &&caption) const;
+
+  tl_object_ptr<telegram_api::inputBotInlineMessageMediaAuto> get_input_bot_inline_message_media_auto(
+      const FormattedText &caption, tl_object_ptr<telegram_api::ReplyMarkup> &&input_reply_markup) const;
+
+  Result<tl_object_ptr<telegram_api::InputBotInlineMessage>> get_inline_message(
+      tl_object_ptr<td_api::InputMessageContent> &&input_message_content,
+      tl_object_ptr<td_api::ReplyMarkup> &&reply_markup_ptr,
+      int32 allowed_media_content_id) const TD_WARN_UNUSED_RESULT;  // TODO make static
+
+  bool register_inline_message_content(int64 query_id, const string &result_id, FileId file_id,
+                                       tl_object_ptr<telegram_api::BotInlineMessage> &&inline_message,
+                                       int32 allowed_media_content_id, Photo *photo = nullptr, Game *game = nullptr);
+
+  tl_object_ptr<td_api::photoSize> register_thumbnail(
+      tl_object_ptr<telegram_api::WebDocument> &&web_document_ptr) const;
+
+  static string get_web_document_url(const tl_object_ptr<telegram_api::WebDocument> &web_document_ptr);
+  static string get_web_document_content_type(const tl_object_ptr<telegram_api::WebDocument> &web_document_ptr);
+
+  bool update_bot_usage(UserId bot_user_id);
+
+  void save_recently_used_bots();
+  bool load_recently_used_bots(Promise<Unit> &promise);
+
+  tl_object_ptr<td_api::inlineQueryResults> decrease_pending_request_count(uint64 query_hash);
+
+  static void on_drop_inline_query_result_timeout_callback(void *inline_queries_manager_ptr, int64 query_hash);
+
+  void loop() override;
+
+  void tear_down() override;
+
+  int32 recently_used_bots_loaded_ = 0;  // 0 - not loaded, 1 - load request was sent, 2 - loaded
+  MultiPromiseActor resolve_recent_inline_bots_multipromise_;
+
+  vector<UserId> recently_used_bot_user_ids_;
+
+  struct PendingInlineQuery {
+    uint64 query_hash;
+    UserId bot_user_id;
+    DialogId dialog_id;
+    Location user_location;
+    string query;
+    string offset;
+    Promise<Unit> promise;
+  };
+
+  double next_inline_query_time_ = -1.0;
+  unique_ptr<PendingInlineQuery> pending_inline_query_;
+  NetQueryRef sent_query_;
+
+  struct InlineQueryResult {
+    tl_object_ptr<td_api::inlineQueryResults> results;
+    double cache_expire_time;
+    int32 pending_request_count;
+  };
+
+  MultiTimeout drop_inline_query_result_timeout_;
+  std::unordered_map<uint64, InlineQueryResult> inline_query_results_;  // query_hash -> result
+
+  struct InlineMessageContent {
+    unique_ptr<MessageContent> message_content;
+    unique_ptr<ReplyMarkup> message_reply_markup;
+    bool disable_web_page_preview;
+  };
+
+  std::unordered_map<int64, std::unordered_map<string, InlineMessageContent>>
+      inline_message_contents_;  // query_id -> [result_id -> inline_message_content]
+
+  std::unordered_map<int64, UserId> query_id_to_bot_user_id_;
+
+  Td *td_;
+  ActorShared<> parent_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Location.cpp b/libs/tdlib/td/td/telegram/Location.cpp
new file mode 100644
index 0000000000..1d5fe0db92
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Location.cpp
@@ -0,0 +1,175 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/Location.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+
+#include <cmath>
+
+namespace td {
+
+void Location::init(double latitude, double longitude) {
+  if (std::isfinite(latitude) && std::isfinite(longitude) && std::abs(latitude) <= 90 && std::abs(longitude) <= 180) {
+    is_empty_ = false;
+    latitude_ = latitude;
+    longitude_ = longitude;
+  }
+}
+
+Location::Location(double latitude, double longitude) {
+  init(latitude, longitude);
+}
+
+Location::Location(const tl_object_ptr<secret_api::decryptedMessageMediaGeoPoint> &geo_point)
+    : Location(geo_point->lat_, geo_point->long_) {
+}
+
+Location::Location(const tl_object_ptr<telegram_api::GeoPoint> &geo_point_ptr) {
+  if (geo_point_ptr == nullptr) {
+    return;
+  }
+  switch (geo_point_ptr->get_id()) {
+    case telegram_api::geoPointEmpty::ID:
+      break;
+    case telegram_api::geoPoint::ID: {
+      auto geo_point = static_cast<const telegram_api::geoPoint *>(geo_point_ptr.get());
+      init(geo_point->lat_, geo_point->long_);
+      break;
+    }
+    default:
+      UNREACHABLE();
+      break;
+  }
+}
+
+Location::Location(const tl_object_ptr<td_api::location> &location) {
+  if (location == nullptr) {
+    return;
+  }
+
+  init(location->latitude_, location->longitude_);
+}
+
+bool Location::empty() const {
+  return is_empty_;
+}
+
+tl_object_ptr<td_api::location> Location::get_location_object() const {
+  if (empty()) {
+    return nullptr;
+  }
+  return make_tl_object<td_api::location>(latitude_, longitude_);
+}
+
+tl_object_ptr<telegram_api::InputGeoPoint> Location::get_input_geo_point() const {
+  if (empty()) {
+    LOG(ERROR) << "Location is empty";
+    return make_tl_object<telegram_api::inputGeoPointEmpty>();
+  }
+
+  return make_tl_object<telegram_api::inputGeoPoint>(latitude_, longitude_);
+}
+
+tl_object_ptr<telegram_api::inputMediaGeoPoint> Location::get_input_media_geo_point() const {
+  return make_tl_object<telegram_api::inputMediaGeoPoint>(get_input_geo_point());
+}
+
+SecretInputMedia Location::get_secret_input_media_geo_point() const {
+  return SecretInputMedia{nullptr, make_tl_object<secret_api::decryptedMessageMediaGeoPoint>(latitude_, longitude_)};
+}
+
+bool operator==(const Location &lhs, const Location &rhs) {
+  if (lhs.is_empty_) {
+    return rhs.is_empty_;
+  }
+  return !rhs.is_empty_ && std::abs(lhs.latitude_ - rhs.latitude_) < 1e-6 &&
+         std::abs(lhs.longitude_ - rhs.longitude_) < 1e-6;
+}
+
+bool operator!=(const Location &lhs, const Location &rhs) {
+  return !(lhs == rhs);
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const Location &location) {
+  if (location.empty()) {
+    return string_builder << "Location[empty]";
+  }
+  return string_builder << "Location[latitude = " << location.latitude_ << ", longitude = " << location.longitude_
+                        << "]";
+}
+
+Venue::Venue(const tl_object_ptr<telegram_api::GeoPoint> &geo_point_ptr, string title, string address, string provider,
+             string id)
+    : location_(geo_point_ptr)
+    , title_(std::move(title))
+    , address_(std::move(address))
+    , provider_(std::move(provider))
+    , id_(std::move(id)) {
+}
+
+Venue::Venue(Location location, string title, string address, string provider, string id)
+    : location_(location)
+    , title_(std::move(title))
+    , address_(std::move(address))
+    , provider_(std::move(provider))
+    , id_(std::move(id)) {
+}
+
+Venue::Venue(const tl_object_ptr<td_api::venue> &venue)
+    : location_(venue->location_)
+    , title_(venue->title_)
+    , address_(venue->address_)
+    , provider_(venue->provider_)
+    , id_(venue->id_) {
+}
+
+bool Venue::empty() const {
+  return location_.empty();
+}
+
+tl_object_ptr<td_api::venue> Venue::get_venue_object() const {
+  return make_tl_object<td_api::venue>(location_.get_location_object(), title_, address_, provider_, id_);
+}
+
+tl_object_ptr<telegram_api::inputMediaVenue> Venue::get_input_media_venue() const {
+  return make_tl_object<telegram_api::inputMediaVenue>(location_.get_input_geo_point(), title_, address_, provider_,
+                                                       id_, "");
+}
+
+SecretInputMedia Venue::get_secret_input_media_venue() const {
+  return SecretInputMedia{nullptr,
+                          make_tl_object<secret_api::decryptedMessageMediaVenue>(
+                              location_.get_latitude(), location_.get_longitude(), title_, address_, provider_, id_)};
+}
+
+tl_object_ptr<telegram_api::inputBotInlineMessageMediaVenue> Venue::get_input_bot_inline_message_media_venue(
+    int32 flags, tl_object_ptr<telegram_api::ReplyMarkup> &&reply_markup) const {
+  return make_tl_object<telegram_api::inputBotInlineMessageMediaVenue>(
+      flags, location_.get_input_geo_point(), title_, address_, provider_, id_, std::move(reply_markup));
+}
+
+bool operator==(const Venue &lhs, const Venue &rhs) {
+  return lhs.location_ == rhs.location_ && lhs.title_ == rhs.title_ && lhs.address_ == rhs.address_ &&
+         lhs.provider_ == rhs.provider_ && lhs.id_ == rhs.id_;
+}
+
+bool operator!=(const Venue &lhs, const Venue &rhs) {
+  return !(lhs == rhs);
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const Venue &venue) {
+  return string_builder << "Venue[location = " << venue.location_ << ", title = " << venue.title_
+                        << ", address = " << venue.address_ << ", provider = " << venue.provider_
+                        << ", id = " << venue.id_ << "]";
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Location.h b/libs/tdlib/td/td/telegram/Location.h
new file mode 100644
index 0000000000..3ab7175206
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Location.h
@@ -0,0 +1,146 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tl_helpers.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/SecretInputMedia.h"
+
+namespace td {
+
+class Location {
+  bool is_empty_ = true;
+  double latitude_ = 0.0;
+  double longitude_ = 0.0;
+
+  friend bool operator==(const Location &lhs, const Location &rhs);
+  friend bool operator!=(const Location &lhs, const Location &rhs);
+
+  friend StringBuilder &operator<<(StringBuilder &string_builder, const Location &location);
+
+  void init(double latitude, double longitude);
+
+ public:
+  Location() = default;
+
+  Location(double latitude, double longitude);
+
+  explicit Location(const tl_object_ptr<secret_api::decryptedMessageMediaGeoPoint> &geo_point);
+
+  explicit Location(const tl_object_ptr<telegram_api::GeoPoint> &geo_point_ptr);
+
+  explicit Location(const tl_object_ptr<td_api::location> &location);
+
+  bool empty() const;
+
+  tl_object_ptr<td_api::location> get_location_object() const;
+
+  tl_object_ptr<telegram_api::InputGeoPoint> get_input_geo_point() const;
+
+  tl_object_ptr<telegram_api::inputMediaGeoPoint> get_input_media_geo_point() const;
+
+  double get_latitude() const {
+    return latitude_;
+  }
+  double get_longitude() const {
+    return longitude_;
+  }
+  SecretInputMedia get_secret_input_media_geo_point() const;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    using td::store;
+    BEGIN_STORE_FLAGS();
+    STORE_FLAG(is_empty_);
+    END_STORE_FLAGS();
+    store(latitude_, storer);
+    store(longitude_, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    using td::parse;
+    BEGIN_PARSE_FLAGS();
+    PARSE_FLAG(is_empty_);
+    END_PARSE_FLAGS();
+    parse(latitude_, parser);
+    parse(longitude_, parser);
+  }
+};
+
+bool operator==(const Location &lhs, const Location &rhs);
+bool operator!=(const Location &lhs, const Location &rhs);
+
+StringBuilder &operator<<(StringBuilder &string_builder, const Location &location);
+
+class Venue {
+  Location location_;
+  string title_;
+  string address_;
+  string provider_;
+  string id_;
+
+  friend bool operator==(const Venue &lhs, const Venue &rhs);
+  friend bool operator!=(const Venue &lhs, const Venue &rhs);
+
+  friend StringBuilder &operator<<(StringBuilder &string_builder, const Venue &venue);
+
+ public:
+  Venue() = default;
+
+  Venue(const tl_object_ptr<telegram_api::GeoPoint> &geo_point_ptr, string title, string address, string provider,
+        string id);
+
+  Venue(Location location, string title, string address, string provider, string id);
+
+  explicit Venue(const tl_object_ptr<td_api::venue> &venue);
+
+  bool empty() const;
+
+  tl_object_ptr<td_api::venue> get_venue_object() const;
+
+  tl_object_ptr<telegram_api::inputMediaVenue> get_input_media_venue() const;
+
+  SecretInputMedia get_secret_input_media_venue() const;
+
+  // TODO very strange function
+  tl_object_ptr<telegram_api::inputBotInlineMessageMediaVenue> get_input_bot_inline_message_media_venue(
+      int32 flags, tl_object_ptr<telegram_api::ReplyMarkup> &&reply_markup) const;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    using td::store;
+    store(location_, storer);
+    store(title_, storer);
+    store(address_, storer);
+    store(provider_, storer);
+    store(id_, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    using td::parse;
+    parse(location_, parser);
+    parse(title_, parser);
+    parse(address_, parser);
+    parse(provider_, parser);
+    parse(id_, parser);
+  }
+};
+
+bool operator==(const Venue &lhs, const Venue &rhs);
+bool operator!=(const Venue &lhs, const Venue &rhs);
+
+StringBuilder &operator<<(StringBuilder &string_builder, const Venue &venue);
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Log.cpp b/libs/tdlib/td/td/telegram/Log.cpp
new file mode 100644
index 0000000000..5aff20a87c
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Log.cpp
@@ -0,0 +1,59 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/Log.h"
+
+#include "td/utils/common.h"
+#include "td/utils/FileLog.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+
+namespace td {
+
+static FileLog file_log;
+static TsLog ts_log(&file_log);
+static int64 max_log_file_size = 10 << 20;
+static Log::FatalErrorCallbackPtr fatal_error_callback;
+
+static void fatal_error_callback_wrapper(CSlice message) {
+  CHECK(fatal_error_callback != nullptr);
+  fatal_error_callback(message.c_str());
+}
+
+bool Log::set_file_path(string file_path) {
+  if (file_path.empty()) {
+    log_interface = default_log_interface;
+    return true;
+  }
+
+  if (file_log.init(file_path, max_log_file_size)) {
+    log_interface = &ts_log;
+    return true;
+  }
+
+  return false;
+}
+
+void Log::set_max_file_size(int64 max_file_size) {
+  max_log_file_size = max(max_file_size, static_cast<int64>(0));
+  file_log.set_rotate_threshold(max_log_file_size);
+}
+
+void Log::set_verbosity_level(int new_verbosity_level) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(FATAL) + new_verbosity_level);
+}
+
+void Log::set_fatal_error_callback(FatalErrorCallbackPtr callback) {
+  if (callback == nullptr) {
+    fatal_error_callback = nullptr;
+    set_log_fatal_error_callback(nullptr);
+  } else {
+    fatal_error_callback = callback;
+    set_log_fatal_error_callback(fatal_error_callback_wrapper);
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Log.h b/libs/tdlib/td/td/telegram/Log.h
new file mode 100644
index 0000000000..7d5e0f4345
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Log.h
@@ -0,0 +1,80 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+/**
+ * \file
+ * C++ interface for managing the internal logging of TDLib.
+ * By default TDLib writes logs to stderr or an OS specific log and uses a verbosity level of 5.
+ */
+
+#include <cstdint>
+#include <string>
+
+namespace td {
+
+/**
+ * Interface for managing the internal logging of TDLib.
+ * By default TDLib writes logs to stderr or an OS specific log and uses a verbosity level of 5.
+ */
+class Log {
+ public:
+  /**
+   * Sets the path to the file to where the internal TDLib log will be written.
+   * By default TDLib writes logs to stderr or an OS specific log.
+   * Use this method to write the log to a file instead.
+   *
+   * \param[in]  file_path Path to a file where the internal TDLib log will be written. Use an empty path to
+   *                       switch back to the default logging behaviour.
+   * \return True on success, or false otherwise, i.e. if the file can't be opened for writing.
+   */
+  static bool set_file_path(std::string file_path);
+
+  /**
+   * Sets maximum size of the file to where the internal TDLib log is written before the file will be auto-rotated.
+   * Unused if log is not written to a file. Defaults to 10 MB.
+   *
+   * \param[in]  max_file_size Maximum size of the file to where the internal TDLib log is written before the file
+   *                           will be auto-rotated. Should be positive.
+   */
+  static void set_max_file_size(std::int64_t max_file_size);
+
+  /**
+   * Sets the verbosity level of the internal logging of TDLib.
+   * By default the TDLib uses a verbosity level of 5 for logging.
+   *
+   * \param[in]  new_verbosity_level New value of the verbosity level for logging.
+   *                                 Value 0 corresponds to fatal errors,
+   *                                 value 1 corresponds to errors,
+   *                                 value 2 corresponds to warnings and debug warnings,
+   *                                 value 3 corresponds to informational,
+   *                                 value 4 corresponds to debug,
+   *                                 value 5 corresponds to verbose debug,
+   *                                 value greater than 5 and up to 1024 can be used to enable even more logging.
+   */
+  static void set_verbosity_level(int new_verbosity_level);
+
+  /**
+   * A type of callback function that will be called when a fatal error happens.
+   *
+   * \param error_message Null-terminated string with a description of a happened fatal error.
+   */
+  using FatalErrorCallbackPtr = void (*)(const char *error_message);
+
+  /**
+   * Sets the callback that will be called when a fatal error happens.
+   * None of the TDLib methods can be called from the callback.
+   * The TDLib will crash as soon as callback returns.
+   * By default the callback is not set.
+   *
+   * \param[in]  callback Callback that will be called when a fatal error happens.
+   *                      Pass nullptr to remove the callback.
+   */
+  static void set_fatal_error_callback(FatalErrorCallbackPtr callback);
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/LogDotNet.cpp b/libs/tdlib/td/td/telegram/LogDotNet.cpp
new file mode 100644
index 0000000000..97e33c440a
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/LogDotNet.cpp
@@ -0,0 +1,56 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/Log.h"
+
+#include "td/utils/port/CxCli.h"
+
+#include <cstdint>
+
+namespace Telegram {
+namespace Td {
+
+using namespace CxCli;
+
+/// <summary>
+/// Class for managing internal TDLib logging.
+/// </summary>
+public ref class Log sealed {
+public:
+  /// <summary>
+  /// Changes TDLib log verbosity.
+  /// </summary>
+  /// <param name="verbosityLevel">New value of log verbosity level. Must be non-negative.
+  /// Value 0 means FATAL, value 1 means ERROR, value 2 means WARNING, value 3 means INFO, value 4 means DEBUG,
+  /// value greater than 4 can be used to enable even more logging.
+  /// Default value of the log verbosity level is 5.</param>
+  static void SetVerbosityLevel(int verbosityLevel) {
+    ::td::Log::set_verbosity_level(verbosityLevel);
+  }
+
+  /// <summary>
+  /// Sets file path for writing TDLib internal log. By default TDLib writes logs to the System.err.
+  /// Use this method to write the log to a file instead.
+  /// </summary>
+  /// <param name="filePath">Path to a file for writing TDLib internal log. Use an empty path to switch back to logging
+  /// to the System.err.</param>
+  /// <returns>Returns whether opening the log file succeeded.</returns>
+  static bool SetFilePath(String^ filePath) {
+    return ::td::Log::set_file_path(string_to_unmanaged(filePath));
+  }
+
+  /// <summary>
+  /// Changes maximum size of TDLib log file.
+  /// </summary>
+  /// <param name="maxFileSize">Maximum size of the file to where the internal TDLib log is written
+  /// before the file will be auto-rotated. Must be positive. Defaults to 10 MB.</param>
+  static void SetMaxFileSize(std::int64_t maxFileSize) {
+    ::td::Log::set_max_file_size(maxFileSize);
+  }
+};
+
+}  // namespace Td
+}  // namespace Telegram
diff --git a/libs/tdlib/td/td/telegram/MessageEntity.cpp b/libs/tdlib/td/td/telegram/MessageEntity.cpp
new file mode 100644
index 0000000000..7af90fb0b0
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/MessageEntity.cpp
@@ -0,0 +1,2183 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/MessageEntity.h"
+
+#include "td/telegram/ContactsManager.h"
+#include "td/telegram/misc.h"
+
+#include "td/utils/HttpUrl.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/unicode.h"
+#include "td/utils/utf8.h"
+
+#include <algorithm>
+#include <cstring>
+#include <tuple>
+#include <unordered_set>
+
+namespace td {
+
+StringBuilder &operator<<(StringBuilder &string_builder, const MessageEntity &message_entity) {
+  bool has_argument = false;
+  string_builder << '[';
+  switch (message_entity.type) {
+    case MessageEntity::Type::Mention:
+      string_builder << "Mention";
+      break;
+    case MessageEntity::Type::Hashtag:
+      string_builder << "Hashtag";
+      break;
+    case MessageEntity::Type::BotCommand:
+      string_builder << "BotCommand";
+      break;
+    case MessageEntity::Type::Url:
+      string_builder << "Url";
+      break;
+    case MessageEntity::Type::EmailAddress:
+      string_builder << "EmailAddress";
+      break;
+    case MessageEntity::Type::Bold:
+      string_builder << "Bold";
+      break;
+    case MessageEntity::Type::Italic:
+      string_builder << "Italic";
+      break;
+    case MessageEntity::Type::Code:
+      string_builder << "Code";
+      break;
+    case MessageEntity::Type::Pre:
+      string_builder << "Pre";
+      break;
+    case MessageEntity::Type::PreCode:
+      string_builder << "PreCode";
+      has_argument = true;
+      break;
+    case MessageEntity::Type::TextUrl:
+      string_builder << "TextUrl";
+      has_argument = true;
+      break;
+    case MessageEntity::Type::MentionName:
+      string_builder << "MentionName";
+      break;
+    case MessageEntity::Type::Cashtag:
+      string_builder << "Cashtag";
+      break;
+    case MessageEntity::Type::PhoneNumber:
+      string_builder << "PhoneNumber";
+      break;
+    default:
+      UNREACHABLE();
+      string_builder << "Impossible";
+      break;
+  }
+
+  string_builder << ", offset = " << message_entity.offset << ", length = " << message_entity.length;
+  if (has_argument) {
+    string_builder << ", argument = \"" << message_entity.argument << "\"";
+  }
+  if (message_entity.user_id.is_valid()) {
+    string_builder << ", " << message_entity.user_id;
+  }
+  string_builder << ']';
+  return string_builder;
+}
+
+tl_object_ptr<td_api::TextEntityType> MessageEntity::get_text_entity_type_object() const {
+  switch (type) {
+    case MessageEntity::Type::Mention:
+      return make_tl_object<td_api::textEntityTypeMention>();
+    case MessageEntity::Type::Hashtag:
+      return make_tl_object<td_api::textEntityTypeHashtag>();
+    case MessageEntity::Type::BotCommand:
+      return make_tl_object<td_api::textEntityTypeBotCommand>();
+    case MessageEntity::Type::Url:
+      return make_tl_object<td_api::textEntityTypeUrl>();
+    case MessageEntity::Type::EmailAddress:
+      return make_tl_object<td_api::textEntityTypeEmailAddress>();
+    case MessageEntity::Type::Bold:
+      return make_tl_object<td_api::textEntityTypeBold>();
+    case MessageEntity::Type::Italic:
+      return make_tl_object<td_api::textEntityTypeItalic>();
+    case MessageEntity::Type::Code:
+      return make_tl_object<td_api::textEntityTypeCode>();
+    case MessageEntity::Type::Pre:
+      return make_tl_object<td_api::textEntityTypePre>();
+    case MessageEntity::Type::PreCode:
+      return make_tl_object<td_api::textEntityTypePreCode>(argument);
+    case MessageEntity::Type::TextUrl:
+      return make_tl_object<td_api::textEntityTypeTextUrl>(argument);
+    case MessageEntity::Type::MentionName:
+      return make_tl_object<td_api::textEntityTypeMentionName>(user_id.get());
+    case MessageEntity::Type::Cashtag:
+      return make_tl_object<td_api::textEntityTypeCashtag>();
+    case MessageEntity::Type::PhoneNumber:
+      return make_tl_object<td_api::textEntityTypePhoneNumber>();
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+tl_object_ptr<td_api::textEntity> MessageEntity::get_text_entity_object() const {
+  return make_tl_object<td_api::textEntity>(offset, length, get_text_entity_type_object());
+}
+
+vector<tl_object_ptr<td_api::textEntity>> get_text_entities_object(const vector<MessageEntity> &entities) {
+  vector<tl_object_ptr<td_api::textEntity>> result;
+  result.reserve(entities.size());
+
+  for (auto &entity : entities) {
+    result.push_back(entity.get_text_entity_object());
+  }
+
+  return result;
+}
+
+static bool is_word_character(uint32 a) {
+  switch (get_unicode_simple_category(a)) {
+    case UnicodeSimpleCategory::Letter:
+    case UnicodeSimpleCategory::DecimalNumber:
+    case UnicodeSimpleCategory::Number:
+      return true;
+    default:
+      return a == '_';
+  }
+}
+
+td_api::object_ptr<td_api::formattedText> get_formatted_text_object(const FormattedText &text) {
+  return td_api::make_object<td_api::formattedText>(text.text, get_text_entities_object(text.entities));
+}
+
+/*
+static bool is_word_boundary(uint32 a, uint32 b) {
+  return is_word_character(a) ^ is_word_character(b);
+}
+*/
+
+static bool is_alpha_digit(uint32 a) {
+  return ('0' <= a && a <= '9') || ('a' <= a && a <= 'z') || ('A' <= a && a <= 'Z');
+}
+
+static bool is_alpha_digit_or_underscore(uint32 a) {
+  return is_alpha_digit(a) || a == '_';
+}
+
+static bool is_alpha_digit_or_underscore_or_minus(uint32 a) {
+  return is_alpha_digit_or_underscore(a) || a == '-';
+}
+
+// This functions just implements corresponding regexps
+// All other fixes will be in other functions
+static vector<Slice> match_mentions(Slice str) {
+  vector<Slice> result;
+  const unsigned char *begin = str.ubegin();
+  const unsigned char *end = str.uend();
+  const unsigned char *ptr = begin;
+
+  // '/(?<=\B)@([a-zA-Z0-9_]{2,32})(?=\b)/u'
+
+  while (true) {
+    ptr = reinterpret_cast<const unsigned char *>(std::memchr(ptr, '@', narrow_cast<int32>(end - ptr)));
+    if (ptr == nullptr) {
+      break;
+    }
+
+    if (ptr != begin) {
+      uint32 prev;
+      next_utf8_unsafe(prev_utf8_unsafe(ptr), &prev);
+
+      if (is_word_character(prev)) {
+        ptr++;
+        continue;
+      }
+    }
+    auto mention_begin = ++ptr;
+    while (ptr != end && is_alpha_digit_or_underscore(*ptr)) {
+      ptr++;
+    }
+    auto mention_end = ptr;
+    auto mention_size = mention_end - mention_begin;
+    if (mention_size < 2 || mention_size > 32) {
+      continue;
+    }
+    uint32 next = 0;
+    if (ptr != end) {
+      next_utf8_unsafe(ptr, &next);
+    }
+    if (is_word_character(next)) {
+      continue;
+    }
+    result.emplace_back(mention_begin - 1, mention_end);
+  }
+  return result;
+}
+
+static vector<Slice> match_bot_commands(Slice str) {
+  vector<Slice> result;
+  const unsigned char *begin = str.ubegin();
+  const unsigned char *end = str.uend();
+  const unsigned char *ptr = begin;
+
+  // '/(?<!\b|[\/<>])\/([a-zA-Z0-9_]{1,64})(?:@([a-zA-Z0-9_]{3,32}))?(?!\B|[\/<>])/u'
+
+  while (true) {
+    ptr = reinterpret_cast<const unsigned char *>(std::memchr(ptr, '/', narrow_cast<int32>(end - ptr)));
+    if (ptr == nullptr) {
+      break;
+    }
+
+    if (ptr != begin) {
+      uint32 prev;
+      next_utf8_unsafe(prev_utf8_unsafe(ptr), &prev);
+
+      if (is_word_character(prev) || prev == '/' || prev == '<' || prev == '>') {
+        ptr++;
+        continue;
+      }
+    }
+
+    auto command_begin = ++ptr;
+    while (ptr != end && is_alpha_digit_or_underscore(*ptr)) {
+      ptr++;
+    }
+    auto command_end = ptr;
+    auto command_size = command_end - command_begin;
+    if (command_size < 1 || command_size > 64) {
+      continue;
+    }
+
+    if (ptr != end && *ptr == '@') {
+      auto mention_begin = ++ptr;
+      while (ptr != end && is_alpha_digit_or_underscore(*ptr)) {
+        ptr++;
+      }
+      auto mention_end = ptr;
+      auto mention_size = mention_end - mention_begin;
+      if (mention_size < 3 || mention_size > 32) {
+        continue;
+      }
+      command_end = ptr;
+    }
+
+    uint32 next = 0;
+    if (ptr != end) {
+      next_utf8_unsafe(ptr, &next);
+    }
+    if (is_word_character(next) || next == '/' || next == '<' || next == '>') {
+      continue;
+    }
+    result.emplace_back(command_begin - 1, command_end);
+  }
+  return result;
+}
+
+static bool is_hashtag_letter(uint32 c, UnicodeSimpleCategory &category) {
+  category = get_unicode_simple_category(c);
+  if (c == '_' || c == 0x200c) {
+    return true;
+  }
+  switch (category) {
+    case UnicodeSimpleCategory::DecimalNumber:
+    case UnicodeSimpleCategory::Letter:
+      return true;
+    default:
+      return false;
+  }
+}
+
+static vector<Slice> match_hashtags(Slice str) {
+  vector<Slice> result;
+  const unsigned char *begin = str.ubegin();
+  const unsigned char *end = str.uend();
+  const unsigned char *ptr = begin;
+
+  // '/(?<=^|[^\d_\pL\x{200c}])#([\d_\pL\x{200c}]{1,256})(?![\d_\pL\x{200c}]*#)/u'
+  // and at least one letter
+
+  UnicodeSimpleCategory category;
+
+  while (true) {
+    ptr = reinterpret_cast<const unsigned char *>(std::memchr(ptr, '#', narrow_cast<int32>(end - ptr)));
+    if (ptr == nullptr) {
+      break;
+    }
+
+    if (ptr != begin) {
+      uint32 prev;
+      next_utf8_unsafe(prev_utf8_unsafe(ptr), &prev);
+
+      if (is_hashtag_letter(prev, category)) {
+        ptr++;
+        continue;
+      }
+    }
+    auto hashtag_begin = ++ptr;
+    size_t hashtag_size = 0;
+    const unsigned char *hashtag_end = nullptr;
+    bool was_letter = false;
+    while (ptr != end) {
+      uint32 code;
+      auto next_ptr = next_utf8_unsafe(ptr, &code);
+      if (!is_hashtag_letter(code, category)) {
+        break;
+      }
+      ptr = next_ptr;
+
+      if (hashtag_size == 255) {
+        hashtag_end = ptr;
+      }
+      if (hashtag_size != 256) {
+        was_letter |= category == UnicodeSimpleCategory::Letter;
+        hashtag_size++;
+      }
+    }
+    if (!hashtag_end) {
+      hashtag_end = ptr;
+    }
+    if (hashtag_size < 1) {
+      continue;
+    }
+    if (ptr != end && ptr[0] == '#') {
+      continue;
+    }
+    if (!was_letter) {
+      continue;
+    }
+    result.emplace_back(hashtag_begin - 1, hashtag_end);
+  }
+  return result;
+}
+
+static vector<Slice> match_cashtags(Slice str) {
+  vector<Slice> result;
+  const unsigned char *begin = str.ubegin();
+  const unsigned char *end = str.uend();
+  const unsigned char *ptr = begin;
+
+  // '/(?<=^|[^$\d_\pL\x{200c}])\$([A-Z]{3,8})(?![$\d_\pL\x{200c}])/u'
+
+  UnicodeSimpleCategory category;
+  while (true) {
+    ptr = reinterpret_cast<const unsigned char *>(std::memchr(ptr, '$', narrow_cast<int32>(end - ptr)));
+    if (ptr == nullptr) {
+      break;
+    }
+
+    if (ptr != begin) {
+      uint32 prev;
+      next_utf8_unsafe(prev_utf8_unsafe(ptr), &prev);
+
+      if (is_hashtag_letter(prev, category) || prev == '$') {
+        ptr++;
+        continue;
+      }
+    }
+
+    auto cashtag_begin = ++ptr;
+    while (ptr != end && 'Z' >= *ptr && *ptr >= 'A') {
+      ptr++;
+    }
+    auto cashtag_end = ptr;
+    auto cashtag_size = cashtag_end - cashtag_begin;
+    if (cashtag_size < 3 || cashtag_size > 8) {
+      continue;
+    }
+
+    if (cashtag_end != end) {
+      uint32 code;
+      next_utf8_unsafe(ptr, &code);
+      if (is_hashtag_letter(code, category) || code == '$') {
+        continue;
+      }
+    }
+
+    result.emplace_back(cashtag_begin - 1, cashtag_end);
+  }
+  return result;
+}
+
+static vector<Slice> match_urls(Slice str) {
+  vector<Slice> result;
+  const unsigned char *begin = str.ubegin();
+  const unsigned char *end = str.uend();
+
+  const auto &is_protocol_symbol = [](uint32 c) {
+    if (c < 0x80) {
+      // do not allow dots in the protocol
+      return is_alpha_digit(c) || c == '+' || c == '-';
+    }
+    // add unicode letters and digits to later discard protocol as invalid
+    return get_unicode_simple_category(c) != UnicodeSimpleCategory::Separator;
+  };
+
+  const auto &is_user_data_symbol = [](uint32 c) {
+    switch (c) {
+      case '\n':
+      case '/':
+      case '[':
+      case ']':
+      case '{':
+      case '}':
+      case '(':
+      case ')':
+      case '\'':
+      case '`':
+      case '<':
+      case '>':
+      case '"':
+      case 0xab:  // «
+      case 0xbb:  // »
+        return false;
+      default:
+        if (0x2000 <= c && c <= 0x206f) {     // General Punctuation
+          return c == 0x200c || c == 0x200d;  // Zero Width Non-Joiner/Joiner
+        }
+        return get_unicode_simple_category(c) != UnicodeSimpleCategory::Separator;
+    }
+  };
+
+  const auto &is_domain_symbol = [](uint32 c) {
+    if (c < 0xc0) {
+      return c == '.' || is_alpha_digit_or_underscore_or_minus(c) || c == '~';
+    }
+    if (0x2000 <= c && c <= 0x206f) {     // General Punctuation
+      return c == 0x200c || c == 0x200d;  // Zero Width Non-Joiner/Joiner
+    }
+    return get_unicode_simple_category(c) != UnicodeSimpleCategory::Separator;
+  };
+
+  const auto &is_path_symbol = [](uint32 c) {
+    switch (c) {
+      case '\n':
+      case '<':
+      case '>':
+      case '"':
+      case 0xab:  // «
+      case 0xbb:  // »
+        return false;
+      default:
+        if (0x2000 <= c && c <= 0x206f) {     // General Punctuation
+          return c == 0x200c || c == 0x200d;  // Zero Width Non-Joiner/Joiner
+        }
+        return get_unicode_simple_category(c) != UnicodeSimpleCategory::Separator;
+    }
+  };
+
+  Slice bad_path_end_chars(".:;,('?!`");
+
+  while (true) {
+    auto dot_pos = str.find('.');
+    if (dot_pos > str.size()) {
+      break;
+    }
+
+    const unsigned char *last_at_ptr = nullptr;
+    const unsigned char *domain_end_ptr = begin + dot_pos;
+    while (domain_end_ptr != end) {
+      uint32 code = 0;
+      auto next_ptr = next_utf8_unsafe(domain_end_ptr, &code);
+      if (code == '@') {
+        last_at_ptr = domain_end_ptr;
+      }
+      if (!is_user_data_symbol(code)) {
+        break;
+      }
+      domain_end_ptr = next_ptr;
+    }
+    domain_end_ptr = last_at_ptr == nullptr ? begin + dot_pos : last_at_ptr + 1;
+    while (domain_end_ptr != end) {
+      uint32 code = 0;
+      auto next_ptr = next_utf8_unsafe(domain_end_ptr, &code);
+      if (!is_domain_symbol(code)) {
+        break;
+      }
+      domain_end_ptr = next_ptr;
+    }
+
+    const unsigned char *domain_begin_ptr = begin + dot_pos;
+    while (domain_begin_ptr != begin) {
+      domain_begin_ptr = prev_utf8_unsafe(domain_begin_ptr);
+      uint32 code = 0;
+      auto next_ptr = next_utf8_unsafe(domain_begin_ptr, &code);
+      if (last_at_ptr == nullptr ? !is_domain_symbol(code) : !is_user_data_symbol(code)) {
+        domain_begin_ptr = next_ptr;
+        break;
+      }
+    }
+    // LOG(ERROR) << "Domain: " << Slice(domain_begin_ptr, domain_end_ptr);
+
+    const unsigned char *url_end_ptr = domain_end_ptr;
+    if (url_end_ptr != end && url_end_ptr[0] == ':') {
+      auto port_end_ptr = url_end_ptr + 1;
+
+      while (port_end_ptr != end && is_digit(port_end_ptr[0])) {
+        port_end_ptr++;
+      }
+
+      auto port_begin_ptr = url_end_ptr + 1;
+      while (port_begin_ptr != port_end_ptr && *port_begin_ptr == '0') {
+        port_begin_ptr++;
+      }
+      if (port_begin_ptr != port_end_ptr && narrow_cast<int>(port_end_ptr - port_begin_ptr) <= 5 &&
+          to_integer<uint32>(Slice(port_begin_ptr, port_end_ptr)) <= 65535) {
+        url_end_ptr = port_end_ptr;
+      }
+    }
+    // LOG(ERROR) << "Domain_port: " << Slice(domain_begin_ptr, url_end_ptr);
+
+    if (url_end_ptr != end && (url_end_ptr[0] == '/' || url_end_ptr[0] == '?' || url_end_ptr[0] == '#')) {
+      auto path_end_ptr = url_end_ptr + 1;
+      while (path_end_ptr != end) {
+        uint32 code = 0;
+        auto next_ptr = next_utf8_unsafe(path_end_ptr, &code);
+        if (!is_path_symbol(code)) {
+          break;
+        }
+        path_end_ptr = next_ptr;
+      }
+      while (bad_path_end_chars.find(path_end_ptr[-1]) < bad_path_end_chars.size()) {
+        path_end_ptr--;
+      }
+      if (url_end_ptr[0] == '/' || url_end_ptr[0] == '#' || path_end_ptr > url_end_ptr + 1) {
+        url_end_ptr = path_end_ptr;
+      }
+    }
+    while (url_end_ptr > begin + dot_pos + 1 && url_end_ptr[-1] == '.') {
+      url_end_ptr--;
+    }
+    // LOG(ERROR) << "Domain_port_path: " << Slice(domain_begin_ptr, url_end_ptr);
+
+    bool is_bad = false;
+    const unsigned char *url_begin_ptr = domain_begin_ptr;
+    if (url_begin_ptr != begin && url_begin_ptr[-1] == '@') {
+      auto user_data_begin_ptr = url_begin_ptr - 1;
+      while (user_data_begin_ptr != begin) {
+        user_data_begin_ptr = prev_utf8_unsafe(user_data_begin_ptr);
+        uint32 code = 0;
+        auto next_ptr = next_utf8_unsafe(user_data_begin_ptr, &code);
+        if (!is_user_data_symbol(code)) {
+          user_data_begin_ptr = next_ptr;
+          break;
+        }
+      }
+      if (user_data_begin_ptr == url_begin_ptr - 1) {
+        is_bad = true;
+      }
+      url_begin_ptr = user_data_begin_ptr;
+    }
+    // LOG(ERROR) << "User_data_port_path: " << Slice(url_begin_ptr, url_end_ptr);
+
+    if (url_begin_ptr != begin) {
+      Slice prefix(begin, url_begin_ptr);
+      if (prefix.size() >= 6 && ends_with(prefix, "://")) {
+        auto protocol_begin_ptr = url_begin_ptr - 3;
+        while (protocol_begin_ptr != begin) {
+          protocol_begin_ptr = prev_utf8_unsafe(protocol_begin_ptr);
+          uint32 code = 0;
+          auto next_ptr = next_utf8_unsafe(protocol_begin_ptr, &code);
+          if (!is_protocol_symbol(code)) {
+            protocol_begin_ptr = next_ptr;
+            break;
+          }
+        }
+        auto protocol = to_lower(Slice(protocol_begin_ptr, url_begin_ptr - 3));
+        if (ends_with(protocol, "http") && protocol != "shttp") {
+          url_begin_ptr = url_begin_ptr - 7;
+        } else if (ends_with(protocol, "https")) {
+          url_begin_ptr = url_begin_ptr - 8;
+        } else if (ends_with(protocol, "sftp")) {
+          url_begin_ptr = url_begin_ptr - 7;
+        } else if (ends_with(protocol, "ftp") && protocol != "tftp") {
+          url_begin_ptr = url_begin_ptr - 6;
+        } else {
+          is_bad = true;
+        }
+      } else {
+        auto prefix_end = prefix.uend();
+        auto prefix_back = prev_utf8_unsafe(prefix_end);
+        uint32 code = 0;
+        next_utf8_unsafe(prefix_back, &code);
+        if (is_word_character(code) || code == '/' || code == '#' || code == '@') {
+          is_bad = true;
+        }
+      }
+    }
+    // LOG(ERROR) << "full: " << Slice(url_begin_ptr, url_end_ptr) << " " << is_bad;
+
+    if (!is_bad) {
+      if (url_end_ptr > begin + dot_pos + 1) {
+        result.emplace_back(url_begin_ptr, url_end_ptr);
+      }
+      while (url_end_ptr != end && url_end_ptr[0] == '.') {
+        url_end_ptr++;
+      }
+    } else {
+      while (url_end_ptr[-1] != '.') {
+        url_end_ptr--;
+      }
+    }
+
+    if (url_end_ptr <= begin + dot_pos) {
+      url_end_ptr = begin + dot_pos + 1;
+    }
+    str = str.substr(url_end_ptr - begin);
+    begin = url_end_ptr;
+  }
+
+  return result;
+}
+
+bool is_email_address(Slice str) {
+  // /^([a-z0-9_-]{0,26}[.+]){0,10}[a-z0-9_-]{1,35}@(([a-z0-9][a-z0-9_-]{0,28})?[a-z0-9][.]){1,6}[a-z]{2,6}$/i
+  Slice userdata;
+  Slice domain;
+  std::tie(userdata, domain) = split(str, '@');
+  vector<Slice> userdata_parts;
+  size_t prev = 0;
+  for (size_t i = 0; i < userdata.size(); i++) {
+    if (userdata[i] == '.' || userdata[i] == '+') {
+      userdata_parts.push_back(userdata.substr(prev, i - prev));
+      prev = i + 1;
+    }
+  }
+  userdata_parts.push_back(userdata.substr(prev));
+  if (userdata_parts.size() >= 12) {
+    return false;
+  }
+  for (auto &part : userdata_parts) {
+    for (auto c : part) {
+      if (!is_alpha_digit_or_underscore_or_minus(c)) {
+        return false;
+      }
+    }
+  }
+  if (userdata_parts.back().empty() || userdata_parts.back().size() >= 36) {
+    return false;
+  }
+  userdata_parts.pop_back();
+  for (auto &part : userdata_parts) {
+    if (part.size() >= 27) {
+      return false;
+    }
+  }
+
+  vector<Slice> domain_parts = full_split(domain, '.');
+  if (domain_parts.size() <= 1 || domain_parts.size() > 7) {
+    return false;
+  }
+  if (domain_parts.back().size() <= 1 || domain_parts.back().size() >= 7) {
+    return false;
+  }
+  for (auto c : domain_parts.back()) {
+    if (!is_alpha(c)) {
+      return false;
+    }
+  }
+  domain_parts.pop_back();
+  for (auto &part : domain_parts) {
+    if (part.empty() || part.size() >= 31) {
+      return false;
+    }
+    for (auto c : part) {
+      if (!is_alpha_digit_or_underscore_or_minus(c)) {
+        return false;
+      }
+    }
+    if (!is_alpha_digit(part[0])) {
+      return false;
+    }
+    if (!is_alpha_digit(part.back())) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+static bool is_common_tld(Slice str) {
+  static const std::unordered_set<Slice, SliceHash> tlds(
+      {"aaa", "aarp", "abarth", "abb", "abbott", "abbvie", "abc", "able", "abogado", "abudhabi", "ac", "academy",
+       "accenture", "accountant", "accountants", "aco", "active", "actor", "ad", "adac", "ads", "adult", "ae", "aeg",
+       "aero", "aetna", "af", "afamilycompany", "afl", "africa", "ag", "agakhan", "agency", "ai", "aig", "aigo",
+       "airbus", "airforce", "airtel", "akdn", "al", "alfaromeo", "alibaba", "alipay", "allfinanz", "allstate", "ally",
+       "alsace", "alstom", "am", "americanexpress", "americanfamily", "amex", "amfam", "amica", "amsterdam",
+       "analytics", "android", "anquan", "anz", "ao", "aol", "apartments", "app", "apple", "aq", "aquarelle", "ar",
+       "arab", "aramco", "archi", "army", "arpa", "art", "arte", "as", "asda", "asia", "associates", "at", "athleta",
+       "attorney", "au", "auction", "audi", "audible", "audio", "auspost", "author", "auto", "autos", "avianca", "aw",
+       "aws", "ax", "axa", "az", "azure", "ba", "baby", "baidu", "banamex", "bananarepublic", "band", "bank", "bar",
+       "barcelona", "barclaycard", "barclays", "barefoot", "bargains", "baseball", "basketball", "bauhaus", "bayern",
+       "bb", "bbc", "bbt", "bbva", "bcg", "bcn", "bd", "be", "beats", "beauty", "beer", "bentley", "berlin", "best",
+       "bestbuy", "bet", "bf", "bg", "bh", "bharti", "bi", "bible", "bid", "bike", "bing", "bingo", "bio", "biz", "bj",
+       "black", "blackfriday", "blanco", "blockbuster", "blog", "bloomberg", "blue", "bm", "bms", "bmw", "bn", "bnl",
+       "bnpparibas", "bo", "boats", "boehringer", "bofa", "bom", "bond", "boo", "book", "booking", "boots", "bosch",
+       "bostik", "boston", "bot", "boutique", "box", "br", "bradesco", "bridgestone", "broadway", "broker", "brother",
+       "brussels", "bs", "bt", "budapest", "bugatti", "build", "builders", "business", "buy", "buzz", "bv", "bw", "by",
+       "bz", "bzh", "ca", "cab", "cafe", "cal", "call", "calvinklein", "cam", "camera", "camp", "cancerresearch",
+       "canon", "capetown", "capital", "capitalone", "car", "caravan", "cards", "care", "career", "careers", "cars",
+       "cartier", "casa", "case", "caseih", "cash", "casino", "cat", "catering", "catholic", "cba", "cbn", "cbre",
+       "cbs", "cc", "cd", "ceb", "center", "ceo", "cern", "cf", "cfa", "cfd", "cg", "ch", "chanel", "channel", "chase",
+       "chat", "cheap", "chintai", "christmas", "chrome", "chrysler", "church", "ci", "cipriani", "circle", "cisco",
+       "citadel", "citi", "citic", "city", "cityeats", "ck", "cl", "claims", "cleaning", "click", "clinic", "clinique",
+       "clothing", "cloud", "club", "clubmed", "cm", "cn", "co", "coach", "codes", "coffee", "college", "cologne",
+       "com", "comcast", "commbank", "community", "company", "compare", "computer", "comsec", "condos", "construction",
+       "consulting", "contact", "contractors", "cooking", "cookingchannel", "cool", "coop", "corsica", "country",
+       "coupon", "coupons", "courses", "cr", "credit", "creditcard", "creditunion", "cricket", "crown", "crs", "cruise",
+       "cruises", "csc", "cu", "cuisinella", "cv", "cw", "cx", "cy", "cymru", "cyou", "cz", "dabur", "dad", "dance",
+       "data", "date", "dating", "datsun", "day", "dclk", "dds", "de", "deal", "dealer", "deals", "degree", "delivery",
+       "dell", "deloitte", "delta", "democrat", "dental", "dentist", "desi", "design", "dev", "dhl", "diamonds", "diet",
+       "digital", "direct", "directory", "discount", "discover", "dish", "diy", "dj", "dk", "dm", "dnp", "do", "docs",
+       "doctor", "dodge", "dog", "doha", "domains", "dot", "download", "drive", "dtv", "dubai", "duck", "dunlop",
+       "duns", "dupont", "durban", "dvag", "dvr", "dz", "earth", "eat", "ec", "eco", "edeka", "edu", "education", "ee",
+       "eg", "email", "emerck", "energy", "engineer", "engineering", "enterprises", "epost", "epson", "equipment", "er",
+       "ericsson", "erni", "es", "esq", "estate", "esurance", "et", "etisalat", "eu", "eurovision", "eus", "events",
+       "everbank", "exchange", "expert", "exposed", "express", "extraspace", "fage", "fail", "fairwinds", "faith",
+       "family", "fan", "fans", "farm", "farmers", "fashion", "fast", "fedex", "feedback", "ferrari", "ferrero", "fi",
+       "fiat", "fidelity", "fido", "film", "final", "finance", "financial", "fire", "firestone", "firmdale", "fish",
+       "fishing", "fit", "fitness", "fj", "fk", "flickr", "flights", "flir", "florist", "flowers", "fly", "fm", "fo",
+       "foo", "food", "foodnetwork", "football", "ford", "forex", "forsale", "forum", "foundation", "fox", "fr", "free",
+       "fresenius", "frl", "frogans", "frontdoor", "frontier", "ftr", "fujitsu", "fujixerox", "fun", "fund",
+       "furniture", "futbol", "fyi", "ga", "gal", "gallery", "gallo", "gallup", "game", "games", "gap", "garden", "gb",
+       "gbiz", "gd", "gdn", "ge", "gea", "gent", "genting", "george", "gf", "gg", "ggee", "gh", "gi", "gift", "gifts",
+       "gives", "giving", "gl", "glade", "glass", "gle", "global", "globo", "gm", "gmail", "gmbh", "gmo", "gmx", "gn",
+       "godaddy", "gold", "goldpoint", "golf", "goo", "goodhands", "goodyear", "goog", "google", "gop", "got", "gov",
+       "gp", "gq", "gr", "grainger", "graphics", "gratis", "green", "gripe", "grocery", "group", "gs", "gt", "gu",
+       "guardian", "gucci", "guge", "guide", "guitars", "guru", "gw", "gy", "hair", "hamburg", "hangout", "haus", "hbo",
+       "hdfc", "hdfcbank", "health", "healthcare", "help", "helsinki", "here", "hermes", "hgtv", "hiphop", "hisamitsu",
+       "hitachi", "hiv", "hk", "hkt", "hm", "hn", "hockey", "holdings", "holiday", "homedepot", "homegoods", "homes",
+       "homesense", "honda", "honeywell", "horse", "hospital", "host", "hosting", "hot", "hoteles", "hotels", "hotmail",
+       "house", "how", "hr", "hsbc", "ht", "hu", "hughes", "hyatt", "hyundai", "ibm", "icbc", "ice", "icu", "id", "ie",
+       "ieee", "ifm", "ikano", "il", "im", "imamat", "imdb", "immo", "immobilien", "in", "industries", "infiniti",
+       "info", "ing", "ink", "institute", "insurance", "insure", "int", "intel", "international", "intuit",
+       "investments", "io", "ipiranga", "iq", "ir", "irish", "is", "iselect", "ismaili", "ist", "istanbul", "it",
+       "itau", "itv", "iveco", "iwc", "jaguar", "java", "jcb", "jcp", "je", "jeep", "jetzt", "jewelry", "jio", "jlc",
+       "jll", "jm", "jmp", "jnj", "jo", "jobs", "joburg", "jot", "joy", "jp", "jpmorgan", "jprs", "juegos", "juniper",
+       "kaufen", "kddi", "ke", "kerryhotels", "kerrylogistics", "kerryproperties", "kfh", "kg", "kh", "ki", "kia",
+       "kim", "kinder", "kindle", "kitchen", "kiwi", "km", "kn", "koeln", "komatsu", "kosher", "kp", "kpmg", "kpn",
+       "kr", "krd", "kred", "kuokgroup", "kw", "ky", "kyoto", "kz", "la", "lacaixa", "ladbrokes", "lamborghini",
+       "lamer", "lancaster", "lancia", "lancome", "land", "landrover", "lanxess", "lasalle", "lat", "latino", "latrobe",
+       "law", "lawyer", "lb", "lc", "lds", "lease", "leclerc", "lefrak", "legal", "lego", "lexus", "lgbt", "li",
+       "liaison", "lidl", "life", "lifeinsurance", "lifestyle", "lighting", "like", "lilly", "limited", "limo",
+       "lincoln", "linde", "link", "lipsy", "live", "living", "lixil", "lk", "loan", "loans", "locker", "locus", "loft",
+       "lol", "london", "lotte", "lotto", "love", "lpl", "lplfinancial", "lr", "ls", "lt", "ltd", "ltda", "lu",
+       "lundbeck", "lupin", "luxe", "luxury", "lv", "ly", "ma", "macys", "madrid", "maif", "maison", "makeup", "man",
+       "management", "mango", "map", "market", "marketing", "markets", "marriott", "marshalls", "maserati", "mattel",
+       "mba", "mc", "mckinsey", "md", "me", "med", "media", "meet", "melbourne", "meme", "memorial", "men", "menu",
+       "meo", "merckmsd", "metlife", "mg", "mh", "miami", "microsoft", "mil", "mini", "mint", "mit", "mitsubishi", "mk",
+       "ml", "mlb", "mls", "mm", "mma", "mn", "mo", "mobi", "mobile", "mobily", "moda", "moe", "moi", "mom", "monash",
+       "money", "monster", "mopar", "mormon", "mortgage", "moscow", "moto", "motorcycles", "mov", "movie", "movistar",
+       "mp", "mq", "mr", "ms", "msd", "mt", "mtn", "mtr", "mu", "museum", "mutual", "mv", "mw", "mx", "my", "mz", "na",
+       "nab", "nadex", "nagoya", "name", "nationwide", "natura", "navy", "nba", "nc", "ne", "nec", "net", "netbank",
+       "netflix", "network", "neustar", "new", "newholland", "news", "next", "nextdirect", "nexus", "nf", "nfl", "ng",
+       "ngo", "nhk", "ni", "nico", "nike", "nikon", "ninja", "nissan", "nissay", "nl", "no", "nokia",
+       "northwesternmutual", "norton", "now", "nowruz", "nowtv", "np", "nr", "nra", "nrw", "ntt", "nu", "nyc", "nz",
+       "obi", "observer", "off", "office", "okinawa", "olayan", "olayangroup", "oldnavy", "ollo", "om", "omega", "one",
+       "ong", "onion", "onl", "online", "onyourside", "ooo", "open", "oracle", "orange", "org", "organic", "origins",
+       "osaka", "otsuka", "ott", "ovh", "pa", "page", "panasonic", "panerai", "paris", "pars", "partners", "parts",
+       "party", "passagens", "pay", "pccw", "pe", "pet", "pf", "pfizer", "pg", "ph", "pharmacy", "phd", "philips",
+       "phone", "photo", "photography", "photos", "physio", "piaget", "pics", "pictet", "pictures", "pid", "pin",
+       "ping", "pink", "pioneer", "pizza", "pk", "pl", "place", "play", "playstation", "plumbing", "plus", "pm", "pn",
+       "pnc", "pohl", "poker", "politie", "porn", "post", "pr", "pramerica", "praxi", "press", "prime", "pro", "prod",
+       "productions", "prof", "progressive", "promo", "properties", "property", "protection", "pru", "prudential", "ps",
+       "pt", "pub", "pw", "pwc", "py", "qa", "qpon", "quebec", "quest", "qvc", "racing", "radio", "raid", "re", "read",
+       "realestate", "realtor", "realty", "recipes", "red", "redstone", "redumbrella", "rehab", "reise", "reisen",
+       "reit", "reliance", "ren", "rent", "rentals", "repair", "report", "republican", "rest", "restaurant", "review",
+       "reviews", "rexroth", "rich", "richardli", "ricoh", "rightathome", "ril", "rio", "rip", "rmit", "ro", "rocher",
+       "rocks", "rodeo", "rogers", "room", "rs", "rsvp", "ru", "rugby", "ruhr", "run", "rw", "rwe", "ryukyu", "sa",
+       "saarland", "safe", "safety", "sakura", "sale", "salon", "samsclub", "samsung", "sandvik", "sandvikcoromant",
+       "sanofi", "sap", "sapo", "sarl", "sas", "save", "saxo", "sb", "sbi", "sbs", "sc", "sca", "scb", "schaeffler",
+       "schmidt", "scholarships", "school", "schule", "schwarz", "science", "scjohnson", "scor", "scot", "sd", "se",
+       "search", "seat", "secure", "security", "seek", "select", "sener", "services", "ses", "seven", "sew", "sex",
+       "sexy", "sfr", "sg", "sh", "shangrila", "sharp", "shaw", "shell", "shia", "shiksha", "shoes", "shop", "shopping",
+       "shouji", "show", "showtime", "shriram", "si", "silk", "sina", "singles", "site", "sj", "sk", "ski", "skin",
+       "sky", "skype", "sl", "sling", "sm", "smart", "smile", "sn", "sncf", "so", "soccer", "social", "softbank",
+       "software", "sohu", "solar", "solutions", "song", "sony", "soy", "space", "spiegel", "sport", "spot",
+       "spreadbetting", "sr", "srl", "srt", "st", "stada", "staples", "star", "starhub", "statebank", "statefarm",
+       "statoil", "stc", "stcgroup", "stockholm", "storage", "store", "stream", "studio", "study", "style", "su",
+       "sucks", "supplies", "supply", "support", "surf", "surgery", "suzuki", "sv", "swatch", "swiftcover", "swiss",
+       "sx", "sy", "sydney", "symantec", "systems", "sz", "tab", "taipei", "talk", "taobao", "target", "tatamotors",
+       "tatar", "tattoo", "tax", "taxi", "tc", "tci", "td", "tdk", "team", "tech", "technology", "tel", "telecity",
+       "telefonica", "temasek", "tennis", "teva", "tf", "tg", "th", "thd", "theater", "theatre", "tiaa", "tickets",
+       "tienda", "tiffany", "tips", "tires", "tirol", "tj", "tjmaxx", "tjx", "tk", "tkmaxx", "tl", "tm", "tmall", "tn",
+       "to", "today", "tokyo", "tools", "top", "toray", "toshiba", "total", "tours", "town", "toyota", "toys", "tr",
+       "trade", "trading", "training", "travel", "travelchannel", "travelers", "travelersinsurance", "trust", "trv",
+       "tt", "tube", "tui", "tunes", "tushu", "tv", "tvs", "tw", "tz", "ua", "ubank", "ubs", "uconnect", "ug", "uk",
+       "unicom", "university", "uno", "uol", "ups", "us", "uy", "uz", "va", "vacations", "vana", "vanguard", "vc", "ve",
+       "vegas", "ventures", "verisign", "versicherung", "vet", "vg", "vi", "viajes", "video", "vig", "viking", "villas",
+       "vin", "vip", "virgin", "visa", "vision", "vista", "vistaprint", "viva", "vivo", "vlaanderen", "vn", "vodka",
+       "volkswagen", "volvo", "vote", "voting", "voto", "voyage", "vu", "vuelos", "wales", "walmart", "walter", "wang",
+       "wanggou", "warman", "watch", "watches", "weather", "weatherchannel", "webcam", "weber", "website", "wed",
+       "wedding", "weibo", "weir", "wf", "whoswho", "wien", "wiki", "williamhill", "win", "windows", "wine", "winners",
+       "wme", "wolterskluwer", "woodside", "work", "works", "world", "wow", "ws", "wtc", "wtf", "xbox", "xerox",
+       "xfinity", "xihuan", "xin", "कॉम", "セール", "佛山", "ಭಾರತ", "慈善", "集团", "在线", "한국", "ଭାରତ", "大众汽车",
+       "点看", "คอม", "ভাৰত", "ভারত", "八卦", "موقع", "বাংলা", "公益", "公司", "香格里拉", "网站", "移动", "我爱你",
+       "москва", "қаз", "католик", "онлайн", "сайт", "联通", "срб", "бг", "бел", "קום", "时尚", "微博", "淡马锡",
+       "ファッション", "орг", "नेट", "ストア", "삼성", "சிங்கப்பூர்", "商标", "商店", "商城", "дети", "мкд", "ею",
+       "ポイント", "新闻", "工行", "家電", "كوم", "中文网", "中信", "中国", "中國", "娱乐", "谷歌", "భారత్", "ලංකා",
+       "電訊盈科", "购物", "クラウド", "ભારત", "通販", "भारतम्", "भारत", "भारोत", "网店", "संगठन", "餐厅", "网络", "ком",
+       "укр", "香港", "诺基亚", "食品", "飞利浦", "台湾", "台灣", "手表", "手机", "мон", "الجزائر", "عمان", "ارامكو",
+       "ایران", "العليان", "اتصالات", "امارات", "بازار", "پاکستان", "الاردن", "موبايلي", "بارت", "بھارت", "المغرب",
+       "ابوظبي", "السعودية", "ڀارت", "كاثوليك", "سودان", "همراه", "عراق", "مليسيا", "澳門", "닷컴", "政府", "شبكة",
+       "بيتك", "عرب", "გე", "机构", "组织机构", "健康", "ไทย", "سورية", "招聘", "рус", "рф", "珠宝", "تونس", "大拿",
+       "みんな", "グーグル", "ελ", "世界", "書籍", "ഭാരതം", "ਭਾਰਤ", "网址", "닷넷", "コム", "天主教", "游戏",
+       "vermögensberater", "vermögensberatung", "企业", "信息", "嘉里大酒店", "嘉里", "مصر", "قطر", "广东", "இலங்கை",
+       "இந்தியா", "հայ", "新加坡", "فلسطين", "政务", "xperia", "xxx", "xyz", "yachts", "yahoo", "yamaxun", "yandex",
+       "ye", "yodobashi", "yoga", "yokohama", "you", "youtube", "yt", "yun", "za", "zappos", "zara", "zero", "zip",
+       "zippo", "zm", "zone", "zuerich",
+       // comment for clang-format to prevent him from placing all strings on separate lines
+       "zw"});
+  string str_lower = utf8_to_lower(str);
+  if (str_lower != str && utf8_substr(Slice(str_lower), 1) == utf8_substr(str, 1)) {
+    return false;
+  }
+  return tlds.count(str_lower) > 0;
+}
+
+Slice fix_url(Slice str) {
+  auto full_url = str;
+
+  bool has_protocol = false;
+  auto str_begin = to_lower(str.substr(0, 8));
+  if (begins_with(str_begin, "http://") || begins_with(str_begin, "https://") || begins_with(str_begin, "sftp://") ||
+      begins_with(str_begin, "ftp://")) {
+    auto pos = str.find(':');
+    str = str.substr(pos + 3);
+    has_protocol = true;
+  }
+  auto domain_end = std::min({str.size(), str.find('/'), str.find('?'), str.find('#')});  // TODO server: str.find('#')
+  auto domain = str.substr(0, domain_end);
+  auto path = str.substr(domain_end);
+
+  auto at_pos = domain.find('@');
+  if (at_pos < domain.size()) {
+    domain.remove_prefix(at_pos + 1);
+  }
+  domain.truncate(domain.rfind(':'));
+
+  string domain_lower = domain.str();
+  to_lower_inplace(domain_lower);
+  if (domain_lower == "teiegram.org") {
+    return Slice();
+  }
+
+  int32 balance[3] = {0, 0, 0};
+  size_t path_pos;
+  for (path_pos = 0; path_pos < path.size(); path_pos++) {
+    switch (path[path_pos]) {
+      case '(':
+        balance[0]++;
+        break;
+      case '[':
+        balance[1]++;
+        break;
+      case '{':
+        balance[2]++;
+        break;
+      case ')':
+        balance[0]--;
+        break;
+      case ']':
+        balance[1]--;
+        break;
+      case '}':
+        balance[2]--;
+        break;
+    }
+    if (balance[0] < 0 || balance[1] < 0 || balance[2] < 0) {
+      break;
+    }
+  }
+  Slice bad_path_end_chars(".:;,('?!`");
+  while (path_pos > 0 && bad_path_end_chars.find(path[path_pos - 1]) < bad_path_end_chars.size()) {
+    path_pos--;
+  }
+  full_url.remove_suffix(path.size() - path_pos);
+
+  vector<Slice> domain_parts = full_split(domain, '.');
+  if (domain_parts.size() <= 1) {
+    return Slice();
+  }
+
+  bool is_ipv4 = domain_parts.size() == 4;
+  bool has_non_digit = false;
+  for (auto &part : domain_parts) {
+    if (part.empty() || part.size() >= 64) {
+      return Slice();
+    }
+    if (part.back() == '-') {
+      return Slice();
+    }
+
+    if (!has_non_digit) {
+      if (part.size() > 3) {
+        is_ipv4 = false;
+      }
+      for (auto c : part) {
+        if (!is_digit(c)) {
+          is_ipv4 = false;
+          has_non_digit = true;
+        }
+      }
+      if (part.size() == 3 &&
+          (part[0] >= '3' || (part[0] == '2' && (part[1] >= '6' || (part[1] == '5' && part[2] >= '6'))))) {
+        is_ipv4 = false;
+      }
+      if (part[0] == '0' && part.size() >= 2) {
+        is_ipv4 = false;
+      }
+    }
+  }
+
+  if (is_ipv4) {
+    return full_url;
+  }
+
+  if (!has_non_digit) {
+    return Slice();
+  }
+
+  auto tld = domain_parts.back();
+  if (utf8_length(tld) <= 1) {
+    return Slice();
+  }
+
+  if (begins_with(tld, "xn--")) {
+    if (tld.size() <= 5) {
+      return Slice();
+    }
+    for (auto c : tld.substr(4)) {
+      if (!is_alpha_digit(c)) {
+        return Slice();
+      }
+    }
+  } else {
+    if (tld.find('_') < tld.size()) {
+      return Slice();
+    }
+    if (tld.find('-') < tld.size()) {
+      return Slice();
+    }
+
+    if (!has_protocol && !is_common_tld(tld)) {
+      return Slice();
+    }
+  }
+
+  domain_parts.pop_back();
+  if (domain_parts.back().find('_') < domain_parts.back().size()) {
+    return Slice();
+  }
+
+  return full_url;
+}
+
+const std::unordered_set<Slice, SliceHash> &get_valid_short_usernames() {
+  static const std::unordered_set<Slice, SliceHash> valid_usernames{
+      "ya", "gif", "wiki", "vid", "bing", "pic", "bold", "imdb", "coub", "like", "vote", "giff", "cap"};
+  return valid_usernames;
+}
+
+vector<Slice> find_mentions(Slice str) {
+  auto mentions = match_mentions(str);
+  mentions.erase(std::remove_if(mentions.begin(), mentions.end(),
+                                [](Slice mention) {
+                                  mention.remove_prefix(1);
+                                  if (mention.size() >= 5) {
+                                    return false;
+                                  }
+                                  return get_valid_short_usernames().count(mention) == 0;
+                                }),
+                 mentions.end());
+  return mentions;
+}
+
+vector<Slice> find_bot_commands(Slice str) {
+  return match_bot_commands(str);
+}
+
+vector<Slice> find_hashtags(Slice str) {
+  return match_hashtags(str);
+}
+
+vector<Slice> find_cashtags(Slice str) {
+  return match_cashtags(str);
+}
+
+vector<std::pair<Slice, bool>> find_urls(Slice str) {
+  vector<std::pair<Slice, bool>> result;
+  for (auto url : match_urls(str)) {
+    if (is_email_address(url)) {
+      result.emplace_back(url, true);
+    } else {
+      url = fix_url(url);
+      if (!url.empty()) {
+        result.emplace_back(url, false);
+      }
+    }
+  }
+  return result;
+}
+
+// sorts entities, removes intersecting and empty entities
+static void fix_entities(vector<MessageEntity> &entities) {
+  if (entities.empty()) {
+    return;
+  }
+
+  std::sort(entities.begin(), entities.end());
+
+  int32 last_entity_end = 0;
+  size_t left_entities = 0;
+  for (size_t i = 0; i < entities.size(); i++) {
+    if (entities[i].length > 0 && entities[i].offset >= last_entity_end) {
+      last_entity_end = entities[i].offset + entities[i].length;
+      if (i != left_entities) {
+        entities[left_entities] = std::move(entities[i]);
+      }
+      left_entities++;
+    }
+  }
+  entities.erase(entities.begin() + left_entities, entities.end());
+}
+
+vector<MessageEntity> find_entities(Slice text, bool skip_bot_commands, bool only_urls) {
+  vector<MessageEntity> entities;
+
+  if (!only_urls) {
+    auto mentions = find_mentions(text);
+    for (auto &mention : mentions) {
+      entities.emplace_back(MessageEntity::Type::Mention, narrow_cast<int32>(mention.begin() - text.begin()),
+                            narrow_cast<int32>(mention.size()));
+    }
+
+    if (!skip_bot_commands) {
+      auto bot_commands = find_bot_commands(text);
+      for (auto &bot_command : bot_commands) {
+        entities.emplace_back(MessageEntity::Type::BotCommand, narrow_cast<int32>(bot_command.begin() - text.begin()),
+                              narrow_cast<int32>(bot_command.size()));
+      }
+    }
+
+    auto hashtags = find_hashtags(text);
+    for (auto &hashtag : hashtags) {
+      entities.emplace_back(MessageEntity::Type::Hashtag, narrow_cast<int32>(hashtag.begin() - text.begin()),
+                            narrow_cast<int32>(hashtag.size()));
+    }
+
+    auto cashtags = find_cashtags(text);
+    for (auto &cashtag : cashtags) {
+      entities.emplace_back(MessageEntity::Type::Cashtag, narrow_cast<int32>(cashtag.begin() - text.begin()),
+                            narrow_cast<int32>(cashtag.size()));
+    }
+
+    // TODO find_phone_numbers
+  }
+
+  auto urls = find_urls(text);
+  for (auto &url : urls) {
+    // TODO better find messageEntityUrl
+    auto type = url.second ? MessageEntity::Type::EmailAddress : MessageEntity::Type::Url;
+    if (only_urls && type != MessageEntity::Type::Url) {
+      continue;
+    }
+    auto offset = narrow_cast<int32>(url.first.begin() - text.begin());
+    auto length = narrow_cast<int32>(url.first.size());
+    entities.emplace_back(type, offset, length);
+  }
+
+  if (entities.empty()) {
+    return entities;
+  }
+
+  fix_entities(entities);
+
+  // fix offsets to utf16 offsets
+  const unsigned char *begin = text.ubegin();
+  const unsigned char *ptr = begin;
+  const unsigned char *end = text.uend();
+
+  int32 utf16_pos = 0;
+  for (auto &entity : entities) {
+    int cnt = 2;
+    auto entity_begin = entity.offset;
+    auto entity_end = entity.offset + entity.length;
+
+    int32 pos = static_cast<int32>(ptr - begin);
+    if (entity_begin == pos) {
+      cnt--;
+      entity.offset = utf16_pos;
+    }
+
+    while (ptr != end && cnt > 0) {
+      unsigned char c = ptr[0];
+      utf16_pos += 1 + (c >= 0xf0);
+      ptr = next_utf8_unsafe(ptr, nullptr);
+
+      pos = static_cast<int32>(ptr - begin);
+      if (entity_begin == pos) {
+        cnt--;
+        entity.offset = utf16_pos;
+      } else if (entity_end == pos) {
+        cnt--;
+        entity.length = utf16_pos - entity.offset;
+      }
+    }
+    CHECK(cnt == 0);
+  }
+
+  return entities;
+}
+
+static vector<MessageEntity> merge_entities(vector<MessageEntity> old_entities, vector<MessageEntity> new_entities) {
+  if (new_entities.empty()) {
+    return old_entities;
+  }
+  if (old_entities.empty()) {
+    return new_entities;
+  }
+
+  vector<MessageEntity> result;
+  result.reserve(old_entities.size() + new_entities.size());
+
+  auto new_it = new_entities.begin();
+  auto new_end = new_entities.end();
+  for (auto &old_entity : old_entities) {
+    while (new_it != new_end && new_it->offset + new_it->length <= old_entity.offset) {
+      result.push_back(std::move(*new_it));
+      new_it++;
+    }
+    auto old_entity_end = old_entity.offset + old_entity.length;
+    result.push_back(std::move(old_entity));
+    while (new_it != new_end && new_it->offset < old_entity_end) {
+      new_it++;
+    }
+  }
+  while (new_it != new_end) {
+    result.push_back(std::move(*new_it));
+    new_it++;
+  }
+
+  return result;
+}
+
+string get_first_url(Slice text, const vector<MessageEntity> &entities) {
+  for (auto &entity : entities) {
+    switch (entity.type) {
+      case MessageEntity::Type::Mention:
+        break;
+      case MessageEntity::Type::Hashtag:
+        break;
+      case MessageEntity::Type::BotCommand:
+        break;
+      case MessageEntity::Type::Url:
+        return utf8_utf16_substr(text, entity.offset, entity.length).str();
+      case MessageEntity::Type::EmailAddress:
+        break;
+      case MessageEntity::Type::Bold:
+        break;
+      case MessageEntity::Type::Italic:
+        break;
+      case MessageEntity::Type::Code:
+        break;
+      case MessageEntity::Type::Pre:
+        break;
+      case MessageEntity::Type::PreCode:
+        break;
+      case MessageEntity::Type::TextUrl:
+        return entity.argument;
+      case MessageEntity::Type::MentionName:
+        break;
+      case MessageEntity::Type::Cashtag:
+        break;
+      case MessageEntity::Type::PhoneNumber:
+        break;
+      default:
+        UNREACHABLE();
+    }
+  }
+
+  return string();
+}
+
+static UserId get_link_user_id(Slice url) {
+  auto lower_cased_url = to_lower(url);
+  url = lower_cased_url;
+
+  Slice link_scheme("tg:");
+  if (!begins_with(url, link_scheme)) {
+    return UserId();
+  }
+  url.remove_prefix(link_scheme.size());
+  if (begins_with(url, "//")) {
+    url.remove_prefix(2);
+  }
+
+  Slice host("user");
+  if (!begins_with(url, host)) {
+    return UserId();
+  }
+  url.remove_prefix(host.size());
+  if (begins_with(url, "/")) {
+    url.remove_prefix(1);
+  }
+  if (!begins_with(url, "?")) {
+    return UserId();
+  }
+  url.remove_prefix(1);
+  url.truncate(url.find('#'));
+
+  for (auto parameter : full_split(url, '&')) {
+    Slice key;
+    Slice value;
+    std::tie(key, value) = split(parameter, '=');
+    if (key == Slice("id")) {
+      return UserId(to_integer<int32>(value));
+    }
+  }
+  return UserId();
+}
+
+Result<vector<MessageEntity>> parse_markdown(string &text) {
+  string result;
+  vector<MessageEntity> entities;
+  size_t size = text.size();
+  int32 utf16_offset = 0;
+  for (size_t i = 0; i < size; i++) {
+    auto c = static_cast<unsigned char>(text[i]);
+    if (c == '\\' && (text[i + 1] == '_' || text[i + 1] == '*' || text[i + 1] == '`' || text[i + 1] == '[')) {
+      i++;
+      result.push_back(text[i]);
+      utf16_offset++;
+      continue;
+    }
+    if (c != '_' && c != '*' && c != '`' && c != '[') {
+      if (is_utf8_character_first_code_unit(c)) {
+        utf16_offset += 1 + (c >= 0xf0);  // >= 4 bytes in symbol => surrogaite pair
+      }
+      result.push_back(text[i]);
+      continue;
+    }
+
+    // we are at begin of the entity
+    size_t begin_pos = i;
+    char end_character = text[i];
+    bool is_pre = false;
+    if (c == '[') {
+      end_character = ']';
+    }
+
+    i++;
+
+    string language;
+    if (c == '`' && text[i] == '`' && text[i + 1] == '`') {
+      i += 2;
+      is_pre = true;
+      size_t language_end = i;
+      while (language_end < size && !is_space(text[language_end]) && text[language_end] != '`') {
+        language_end++;
+      }
+      if (i != language_end && language_end < size && text[language_end] != '`') {
+        language.assign(text, i, language_end - i);
+        i = language_end;
+      }
+      // skip one new line in the beginning of the text
+      if (text[i] == '\n' || text[i] == '\r') {
+        if ((text[i + 1] == '\n' || text[i + 1] == '\r') && text[i] != text[i + 1]) {
+          i += 2;
+        } else {
+          i++;
+        }
+      }
+    }
+
+    int32 utf16_entity_length = 0;
+    while (i < size && (text[i] != end_character || (is_pre && !(text[i + 1] == '`' && text[i + 2] == '`')))) {
+      auto cur_ch = static_cast<unsigned char>(text[i]);
+      if (is_utf8_character_first_code_unit(cur_ch)) {
+        utf16_entity_length += 1 + (cur_ch >= 0xf0);  // >= 4 bytes in symbol => surrogaite pair
+      }
+      result.push_back(text[i++]);
+    }
+    if (i == size) {
+      return Status::Error(400, PSLICE() << "Can't find end of the entity starting at byte offset " << begin_pos);
+    }
+
+    if (utf16_entity_length > 0) {
+      switch (c) {
+        case '_':
+          entities.emplace_back(MessageEntity::Type::Italic, utf16_offset, utf16_entity_length);
+          break;
+        case '*':
+          entities.emplace_back(MessageEntity::Type::Bold, utf16_offset, utf16_entity_length);
+          break;
+        case '[': {
+          string url;
+          if (text[i + 1] != '(') {
+            // use text as a url
+            url.assign(text, begin_pos + 1, i - begin_pos - 1);
+          } else {
+            i += 2;
+            while (i < size && text[i] != ')') {
+              url.push_back(text[i++]);
+            }
+          }
+          auto user_id = get_link_user_id(url);
+          if (user_id.is_valid()) {
+            entities.emplace_back(utf16_offset, utf16_entity_length, user_id);
+          } else {
+            auto r_http_url = parse_url(url);
+            if (r_http_url.is_ok() && url.find('.') != string::npos) {
+              entities.emplace_back(MessageEntity::Type::TextUrl, utf16_offset, utf16_entity_length,
+                                    r_http_url.ok().get_url());
+            }
+          }
+          break;
+        }
+        case '`':
+          if (is_pre) {
+            if (language.empty()) {
+              entities.emplace_back(MessageEntity::Type::Pre, utf16_offset, utf16_entity_length);
+            } else {
+              entities.emplace_back(MessageEntity::Type::PreCode, utf16_offset, utf16_entity_length, language);
+            }
+          } else {
+            entities.emplace_back(MessageEntity::Type::Code, utf16_offset, utf16_entity_length);
+          }
+          break;
+        default:
+          UNREACHABLE();
+      }
+      utf16_offset += utf16_entity_length;
+    }
+    if (is_pre) {
+      i += 2;
+    }
+  }
+  text = result;
+  return entities;
+}
+
+static uint32 decode_html_entity(const string &text, size_t &pos) {
+  auto c = static_cast<unsigned char>(text[pos]);
+  if (c != '&') {
+    return 0;
+  }
+
+  size_t end_pos = pos + 1;
+  uint32 res = 0;
+  if (text[pos + 1] == '#') {
+    // numeric character reference
+    end_pos++;
+    if (text[pos + 2] == 'x') {
+      // hexadecimal numeric character reference
+      end_pos++;
+      while (is_hex_digit(text[end_pos])) {
+        res = res * 16 + hex_to_int(text[end_pos++]);
+      }
+    } else {
+      // decimal numeric character reference
+      while (is_digit(text[end_pos])) {
+        res = res * 10 + text[end_pos++] - '0';
+      }
+    }
+    if (res == 0 || res >= 0x10ffff || end_pos - pos >= 10) {
+      return 0;
+    }
+  } else {
+    while (is_alpha(text[end_pos])) {
+      end_pos++;
+    }
+    string entity(text, pos + 1, end_pos - pos - 1);
+    if (entity == "lt") {
+      res = static_cast<uint32>('<');
+    } else if (entity == "gt") {
+      res = static_cast<uint32>('>');
+    } else if (entity == "amp") {
+      res = static_cast<uint32>('&');
+    } else if (entity == "quot") {
+      res = static_cast<uint32>('"');
+    } else {
+      // unsupported literal entity
+      return 0;
+    }
+  }
+
+  if (text[end_pos] == ';') {
+    pos = end_pos + 1;
+  } else {
+    pos = end_pos;
+  }
+  return res;
+}
+
+Result<vector<MessageEntity>> parse_html(string &text) {
+  string result;
+  vector<MessageEntity> entities;
+  size_t size = text.size();
+  int32 utf16_offset = 0;
+  for (size_t i = 0; i < size; i++) {
+    auto c = static_cast<unsigned char>(text[i]);
+    if (c == '&') {
+      auto ch = decode_html_entity(text, i);
+      if (ch != 0) {
+        i--;  // i will be incremented in for
+        utf16_offset += 1 + (ch > 0xffff);
+        append_utf8_character(result, ch);
+        continue;
+      }
+    }
+    if (c != '<') {
+      if (is_utf8_character_first_code_unit(c)) {
+        utf16_offset += 1 + (c >= 0xf0);  // >= 4 bytes in symbol => surrogaite pair
+      }
+      result.push_back(text[i]);
+      continue;
+    }
+
+    // we are at begin of the entity
+    size_t begin_pos = i++;
+    if (text[i] == '/') {
+      return Status::Error(400, PSLICE() << "Unexpected end tag at byte offset " << begin_pos);
+    }
+    while (!is_space(text[i]) && text[i] != '>') {
+      i++;
+    }
+    if (text[i] == 0) {
+      return Status::Error(400, PSLICE() << "Unclosed start tag at byte offset " << begin_pos);
+    }
+
+    string tag_name(text, begin_pos + 1, i - begin_pos - 1);
+    to_lower_inplace(tag_name);
+    if (tag_name != "em" && tag_name != "strong" && tag_name != "a" && tag_name != "b" && tag_name != "i" &&
+        tag_name != "pre" && tag_name != "code") {
+      return Status::Error(400,
+                           PSLICE() << "Unsupported start tag \"" << tag_name << "\" at byte offset " << begin_pos);
+    }
+
+    string url;
+    // string language; TODO PreCode support
+    while (text[i] != '>') {
+      while (text[i] != 0 && is_space(text[i])) {
+        i++;
+      }
+      if (text[i] == '>') {
+        break;
+      }
+      auto attribute_begin_pos = i;
+      while (!is_space(text[i]) && text[i] != '=') {
+        i++;
+      }
+      string attribute_name(text, attribute_begin_pos, i - attribute_begin_pos);
+      if (attribute_name.empty()) {
+        return Status::Error(400, PSLICE() << "Expected equal sign in declaration of attribute of the tag \""
+                                           << tag_name << "\" at byte offset " << begin_pos);
+      }
+      while (text[i] != 0 && is_space(text[i])) {
+        i++;
+      }
+      if (text[i] != '=') {
+        return Status::Error(400, PSLICE() << "Expected equal sign in declaration of attribute of the tag \""
+                                           << tag_name << "\" at byte offset " << begin_pos);
+      }
+      i++;
+      while (text[i] != 0 && is_space(text[i])) {
+        i++;
+      }
+      if (text[i] == 0) {
+        return Status::Error(400, PSLICE() << "Unclosed start tag at byte offset " << begin_pos);
+      }
+
+      string attribute_value;
+      if (text[i] != '\'' && text[i] != '"') {
+        // A name token (a sequence of letters, digits, periods, or hyphens). Name tokens are not case sensitive.
+        auto token_begin_pos = i;
+        while (is_alnum(text[i]) || text[i] == '.' || text[i] == '-') {
+          i++;
+        }
+        attribute_value.assign(text, token_begin_pos, i - token_begin_pos);
+        to_lower_inplace(attribute_value);
+
+        if (!is_space(text[i]) && text[i] != '>') {
+          return Status::Error(400, PSLICE() << "Unexpected end of name token at byte offset " << token_begin_pos);
+        }
+      } else {
+        // A string literal
+        char end_character = text[i++];
+        while (text[i] != end_character && text[i] != 0) {
+          if (text[i] == '&') {
+            auto ch = decode_html_entity(text, i);
+            if (ch != 0) {
+              append_utf8_character(attribute_value, ch);
+              continue;
+            }
+          }
+          attribute_value.push_back(text[i++]);
+        }
+        if (text[i] == end_character) {
+          i++;
+        }
+      }
+      if (text[i] == 0) {
+        return Status::Error(400, PSLICE() << "Unclosed start tag at byte offset " << begin_pos);
+      }
+
+      if (tag_name == "a" && attribute_name == "href") {
+        url = attribute_value;
+      }
+    }
+    i++;
+
+    int32 utf16_entity_length = 0;
+    size_t entity_begin_pos = result.size();
+    while (text[i] != 0 && text[i] != '<') {
+      auto cur_ch = static_cast<unsigned char>(text[i]);
+      if (cur_ch == '&') {
+        auto ch = decode_html_entity(text, i);
+        if (ch != 0) {
+          utf16_entity_length += 1 + (ch > 0xffff);
+          append_utf8_character(result, ch);
+          continue;
+        }
+      }
+      if (is_utf8_character_first_code_unit(cur_ch)) {
+        utf16_entity_length += 1 + (cur_ch >= 0xf0);  // >= 4 bytes in symbol => surrogaite pair
+      }
+      result.push_back(text[i++]);
+    }
+    if (text[i] == 0) {
+      return Status::Error(400,
+                           PSLICE() << "Can't found end tag corresponding to start tag at byte offset " << begin_pos);
+    }
+
+    auto end_tag_begin_pos = i++;
+    if (text[i] != '/') {
+      return Status::Error(400, PSLICE() << "Expected end tag at byte offset " << end_tag_begin_pos);
+    }
+    while (!is_space(text[i]) && text[i] != '>') {
+      i++;
+    }
+    string end_tag_name(text, end_tag_begin_pos + 2, i - end_tag_begin_pos - 2);
+    while (is_space(text[i]) && text[i] != 0) {
+      i++;
+    }
+    if (text[i] != '>') {
+      return Status::Error(400, PSLICE() << "Unclosed end tag at byte offset " << end_tag_begin_pos);
+    }
+    if (!end_tag_name.empty() && end_tag_name != tag_name) {
+      return Status::Error(400, PSLICE() << "Unmatched end tag at byte offset " << end_tag_begin_pos
+                                         << ", expected \"</" << tag_name << ">\", found\"</" << end_tag_name << ">\"");
+    }
+
+    if (utf16_entity_length > 0) {
+      if (tag_name == "i" || tag_name == "em") {
+        entities.emplace_back(MessageEntity::Type::Italic, utf16_offset, utf16_entity_length);
+      } else if (tag_name == "b" || tag_name == "strong") {
+        entities.emplace_back(MessageEntity::Type::Bold, utf16_offset, utf16_entity_length);
+      } else if (tag_name == "a") {
+        if (url.empty()) {
+          url = result.substr(entity_begin_pos);
+        }
+        auto user_id = get_link_user_id(url);
+        if (user_id.is_valid()) {
+          entities.emplace_back(utf16_offset, utf16_entity_length, user_id);
+        } else {
+          auto r_http_url = parse_url(url);
+          if (r_http_url.is_ok() && url.find('.') != string::npos) {
+            entities.emplace_back(MessageEntity::Type::TextUrl, utf16_offset, utf16_entity_length,
+                                  r_http_url.ok().get_url());
+          }
+        }
+      } else if (tag_name == "pre") {
+        entities.emplace_back(MessageEntity::Type::Pre, utf16_offset, utf16_entity_length);
+      } else if (tag_name == "code") {
+        entities.emplace_back(MessageEntity::Type::Code, utf16_offset, utf16_entity_length);
+      }
+      utf16_offset += utf16_entity_length;
+    }
+  }
+  text = result;
+  return entities;
+}
+
+vector<tl_object_ptr<telegram_api::MessageEntity>> get_input_message_entities(const ContactsManager *contacts_manager,
+                                                                              const vector<MessageEntity> &entities) {
+  vector<tl_object_ptr<telegram_api::MessageEntity>> result;
+  for (auto &entity : entities) {
+    switch (entity.type) {
+      case MessageEntity::Type::Mention:
+      case MessageEntity::Type::Hashtag:
+      case MessageEntity::Type::BotCommand:
+      case MessageEntity::Type::Url:
+      case MessageEntity::Type::EmailAddress:
+      case MessageEntity::Type::Cashtag:
+      case MessageEntity::Type::PhoneNumber:
+        continue;
+      case MessageEntity::Type::Bold:
+        result.push_back(make_tl_object<telegram_api::messageEntityBold>(entity.offset, entity.length));
+        break;
+      case MessageEntity::Type::Italic:
+        result.push_back(make_tl_object<telegram_api::messageEntityItalic>(entity.offset, entity.length));
+        break;
+      case MessageEntity::Type::Code:
+        result.push_back(make_tl_object<telegram_api::messageEntityCode>(entity.offset, entity.length));
+        break;
+      case MessageEntity::Type::Pre:
+        result.push_back(make_tl_object<telegram_api::messageEntityPre>(entity.offset, entity.length, string()));
+        break;
+      case MessageEntity::Type::PreCode:
+        result.push_back(make_tl_object<telegram_api::messageEntityPre>(entity.offset, entity.length, entity.argument));
+        break;
+      case MessageEntity::Type::TextUrl:
+        result.push_back(
+            make_tl_object<telegram_api::messageEntityTextUrl>(entity.offset, entity.length, entity.argument));
+        break;
+      case MessageEntity::Type::MentionName: {
+        auto input_user = contacts_manager->get_input_user(entity.user_id);
+        CHECK(input_user != nullptr);
+        result.push_back(make_tl_object<telegram_api::inputMessageEntityMentionName>(entity.offset, entity.length,
+                                                                                     std::move(input_user)));
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+  }
+
+  return result;
+}
+
+vector<tl_object_ptr<secret_api::MessageEntity>> get_input_secret_message_entities(
+    const vector<MessageEntity> &entities) {
+  vector<tl_object_ptr<secret_api::MessageEntity>> result;
+  for (auto &entity : entities) {
+    switch (entity.type) {
+      case MessageEntity::Type::Mention:
+        result.push_back(make_tl_object<secret_api::messageEntityMention>(entity.offset, entity.length));
+        break;
+      case MessageEntity::Type::Hashtag:
+        result.push_back(make_tl_object<secret_api::messageEntityHashtag>(entity.offset, entity.length));
+        break;
+      case MessageEntity::Type::Cashtag:
+        break;
+      case MessageEntity::Type::BotCommand:
+        break;
+      case MessageEntity::Type::Url:
+        result.push_back(make_tl_object<secret_api::messageEntityUrl>(entity.offset, entity.length));
+        break;
+      case MessageEntity::Type::EmailAddress:
+        result.push_back(make_tl_object<secret_api::messageEntityEmail>(entity.offset, entity.length));
+        break;
+      case MessageEntity::Type::Bold:
+        result.push_back(make_tl_object<secret_api::messageEntityBold>(entity.offset, entity.length));
+        break;
+      case MessageEntity::Type::Italic:
+        result.push_back(make_tl_object<secret_api::messageEntityItalic>(entity.offset, entity.length));
+        break;
+      case MessageEntity::Type::Code:
+        result.push_back(make_tl_object<secret_api::messageEntityCode>(entity.offset, entity.length));
+        break;
+      case MessageEntity::Type::Pre:
+        result.push_back(make_tl_object<secret_api::messageEntityPre>(entity.offset, entity.length, string()));
+        break;
+      case MessageEntity::Type::PreCode:
+        result.push_back(make_tl_object<secret_api::messageEntityPre>(entity.offset, entity.length, entity.argument));
+        break;
+      case MessageEntity::Type::TextUrl:
+        result.push_back(
+            make_tl_object<secret_api::messageEntityTextUrl>(entity.offset, entity.length, entity.argument));
+        break;
+      case MessageEntity::Type::MentionName:
+        break;
+      case MessageEntity::Type::PhoneNumber:
+        break;
+      default:
+        UNREACHABLE();
+    }
+  }
+
+  return result;
+}
+
+Result<vector<MessageEntity>> get_message_entities(const ContactsManager *contacts_manager,
+                                                   const vector<tl_object_ptr<td_api::textEntity>> &input_entities) {
+  vector<MessageEntity> entities;
+  for (auto &entity : input_entities) {
+    if (entity == nullptr || entity->type_ == nullptr) {
+      continue;
+    }
+
+    switch (entity->type_->get_id()) {
+      case td_api::textEntityTypeMention::ID:
+      case td_api::textEntityTypeHashtag::ID:
+      case td_api::textEntityTypeBotCommand::ID:
+      case td_api::textEntityTypeUrl::ID:
+      case td_api::textEntityTypeEmailAddress::ID:
+      case td_api::textEntityTypeCashtag::ID:
+      case td_api::textEntityTypePhoneNumber::ID:
+        break;
+      case td_api::textEntityTypeBold::ID:
+        entities.emplace_back(MessageEntity::Type::Bold, entity->offset_, entity->length_);
+        break;
+      case td_api::textEntityTypeItalic::ID:
+        entities.emplace_back(MessageEntity::Type::Italic, entity->offset_, entity->length_);
+        break;
+      case td_api::textEntityTypeCode::ID:
+        entities.emplace_back(MessageEntity::Type::Code, entity->offset_, entity->length_);
+        break;
+      case td_api::textEntityTypePre::ID:
+        entities.emplace_back(MessageEntity::Type::Pre, entity->offset_, entity->length_);
+        break;
+      case td_api::textEntityTypePreCode::ID: {
+        auto entity_pre_code = static_cast<td_api::textEntityTypePreCode *>(entity->type_.get());
+        if (!clean_input_string(entity_pre_code->language_)) {
+          return Status::Error(400, "MessageEntityPreCode.language must be encoded in UTF-8");
+        }
+        entities.emplace_back(MessageEntity::Type::PreCode, entity->offset_, entity->length_,
+                              entity_pre_code->language_);
+        break;
+      }
+      case td_api::textEntityTypeTextUrl::ID: {
+        auto entity_text_url = static_cast<td_api::textEntityTypeTextUrl *>(entity->type_.get());
+        if (!clean_input_string(entity_text_url->url_)) {
+          return Status::Error(400, "MessageEntityTextUrl.url must be encoded in UTF-8");
+        }
+        auto r_http_url = parse_url(entity_text_url->url_);
+        if (r_http_url.is_error()) {
+          return Status::Error(400, PSTRING() << "Wrong message entity: " << r_http_url.error().message());
+        }
+        entities.emplace_back(MessageEntity::Type::TextUrl, entity->offset_, entity->length_,
+                              r_http_url.ok().get_url());
+        break;
+      }
+      case td_api::textEntityTypeMentionName::ID: {
+        auto entity_mention_name = static_cast<td_api::textEntityTypeMentionName *>(entity->type_.get());
+        UserId user_id(entity_mention_name->user_id_);
+        if (!contacts_manager->have_input_user(user_id)) {
+          return Status::Error(7, "Have no access to the user");
+        }
+        entities.emplace_back(entity->offset_, entity->length_, user_id);
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+  }
+  return entities;
+}
+
+vector<MessageEntity> get_message_entities(const ContactsManager *contacts_manager,
+                                           vector<tl_object_ptr<telegram_api::MessageEntity>> &&server_entities,
+                                           const char *source) {
+  vector<MessageEntity> entities;
+  entities.reserve(server_entities.size());
+  for (auto &entity : server_entities) {
+    switch (entity->get_id()) {
+      case telegram_api::messageEntityUnknown::ID:
+        break;
+      case telegram_api::messageEntityMention::ID: {
+        auto entity_mention = static_cast<const telegram_api::messageEntityMention *>(entity.get());
+        entities.emplace_back(MessageEntity::Type::Mention, entity_mention->offset_, entity_mention->length_);
+        break;
+      }
+      case telegram_api::messageEntityHashtag::ID: {
+        auto entity_hashtag = static_cast<const telegram_api::messageEntityHashtag *>(entity.get());
+        entities.emplace_back(MessageEntity::Type::Hashtag, entity_hashtag->offset_, entity_hashtag->length_);
+        break;
+      }
+      case telegram_api::messageEntityCashtag::ID: {
+        auto entity_cashtag = static_cast<const telegram_api::messageEntityCashtag *>(entity.get());
+        entities.emplace_back(MessageEntity::Type::Cashtag, entity_cashtag->offset_, entity_cashtag->length_);
+        break;
+      }
+      case telegram_api::messageEntityPhone::ID: {
+        auto entity_phone = static_cast<const telegram_api::messageEntityPhone *>(entity.get());
+        entities.emplace_back(MessageEntity::Type::PhoneNumber, entity_phone->offset_, entity_phone->length_);
+        break;
+      }
+      case telegram_api::messageEntityBotCommand::ID: {
+        auto entity_bot_command = static_cast<const telegram_api::messageEntityBotCommand *>(entity.get());
+        entities.emplace_back(MessageEntity::Type::BotCommand, entity_bot_command->offset_,
+                              entity_bot_command->length_);
+        break;
+      }
+      case telegram_api::messageEntityUrl::ID: {
+        auto entity_url = static_cast<const telegram_api::messageEntityUrl *>(entity.get());
+        entities.emplace_back(MessageEntity::Type::Url, entity_url->offset_, entity_url->length_);
+        break;
+      }
+      case telegram_api::messageEntityEmail::ID: {
+        auto entity_email = static_cast<const telegram_api::messageEntityEmail *>(entity.get());
+        entities.emplace_back(MessageEntity::Type::EmailAddress, entity_email->offset_, entity_email->length_);
+        break;
+      }
+      case telegram_api::messageEntityBold::ID: {
+        auto entity_bold = static_cast<const telegram_api::messageEntityBold *>(entity.get());
+        entities.emplace_back(MessageEntity::Type::Bold, entity_bold->offset_, entity_bold->length_);
+        break;
+      }
+      case telegram_api::messageEntityItalic::ID: {
+        auto entity_italic = static_cast<const telegram_api::messageEntityItalic *>(entity.get());
+        entities.emplace_back(MessageEntity::Type::Italic, entity_italic->offset_, entity_italic->length_);
+        break;
+      }
+      case telegram_api::messageEntityCode::ID: {
+        auto entity_code = static_cast<const telegram_api::messageEntityCode *>(entity.get());
+        entities.emplace_back(MessageEntity::Type::Code, entity_code->offset_, entity_code->length_);
+        break;
+      }
+      case telegram_api::messageEntityPre::ID: {
+        auto entity_pre = static_cast<telegram_api::messageEntityPre *>(entity.get());
+        if (entity_pre->language_.empty()) {
+          entities.emplace_back(MessageEntity::Type::Pre, entity_pre->offset_, entity_pre->length_);
+        } else {
+          entities.emplace_back(MessageEntity::Type::PreCode, entity_pre->offset_, entity_pre->length_,
+                                std::move(entity_pre->language_));
+        }
+        break;
+      }
+      case telegram_api::messageEntityTextUrl::ID: {
+        // TODO const telegram_api::messageEntityTextUrl *
+        auto entity_text_url = static_cast<telegram_api::messageEntityTextUrl *>(entity.get());
+        auto r_http_url = parse_url(entity_text_url->url_);
+        if (r_http_url.is_error()) {
+          LOG(ERROR) << "Wrong URL entity: \"" << entity_text_url->url_ << "\": " << r_http_url.error().message()
+                     << " from " << source;
+          continue;
+        }
+        entities.emplace_back(MessageEntity::Type::TextUrl, entity_text_url->offset_, entity_text_url->length_,
+                              r_http_url.ok().get_url());
+        break;
+      }
+      case telegram_api::messageEntityMentionName::ID: {
+        auto entity_mention_name = static_cast<const telegram_api::messageEntityMentionName *>(entity.get());
+        UserId user_id(entity_mention_name->user_id_);
+        if (!user_id.is_valid()) {
+          LOG(ERROR) << "Receive invalid " << user_id << " in MentionName from " << source;
+          continue;
+        }
+        if (!contacts_manager->have_user(user_id)) {
+          LOG(ERROR) << "Receive unknown " << user_id << " in MentionName from " << source;
+          continue;
+        }
+        if (!contacts_manager->have_input_user(user_id)) {
+          LOG(ERROR) << "Receive unaccessible " << user_id << " in MentionName from " << source;
+          continue;
+        }
+        entities.emplace_back(entity_mention_name->offset_, entity_mention_name->length_, user_id);
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+  }
+  return entities;
+}
+
+vector<MessageEntity> get_message_entities(vector<tl_object_ptr<secret_api::MessageEntity>> &&secret_entities) {
+  vector<MessageEntity> entities;
+  entities.reserve(secret_entities.size());
+  for (auto &entity : secret_entities) {
+    switch (entity->get_id()) {
+      case secret_api::messageEntityUnknown::ID:
+        break;
+      case secret_api::messageEntityMention::ID:
+        // skip, will find it ourselves
+        break;
+      case secret_api::messageEntityHashtag::ID:
+        // skip, will find it ourselves
+        break;
+      case secret_api::messageEntityCashtag::ID:
+        // skip, will find it ourselves
+        break;
+      case secret_api::messageEntityPhone::ID:
+        // skip, will find it ourselves
+        break;
+      case secret_api::messageEntityBotCommand::ID:
+        // skip all bot commands in secret chats
+        break;
+      case secret_api::messageEntityUrl::ID: {
+        auto entity_url = static_cast<const secret_api::messageEntityUrl *>(entity.get());
+        // TODO skip URL when find_urls will be better
+        entities.emplace_back(MessageEntity::Type::Url, entity_url->offset_, entity_url->length_);
+        break;
+      }
+      case secret_api::messageEntityEmail::ID: {
+        auto entity_email = static_cast<const secret_api::messageEntityEmail *>(entity.get());
+        // TODO skip emails when find_urls will be better
+        entities.emplace_back(MessageEntity::Type::EmailAddress, entity_email->offset_, entity_email->length_);
+        break;
+      }
+      case secret_api::messageEntityBold::ID: {
+        auto entity_bold = static_cast<const secret_api::messageEntityBold *>(entity.get());
+        entities.emplace_back(MessageEntity::Type::Bold, entity_bold->offset_, entity_bold->length_);
+        break;
+      }
+      case secret_api::messageEntityItalic::ID: {
+        auto entity_italic = static_cast<const secret_api::messageEntityItalic *>(entity.get());
+        entities.emplace_back(MessageEntity::Type::Italic, entity_italic->offset_, entity_italic->length_);
+        break;
+      }
+      case secret_api::messageEntityCode::ID: {
+        auto entity_code = static_cast<const secret_api::messageEntityCode *>(entity.get());
+        entities.emplace_back(MessageEntity::Type::Code, entity_code->offset_, entity_code->length_);
+        break;
+      }
+      case secret_api::messageEntityPre::ID: {
+        auto entity_pre = static_cast<secret_api::messageEntityPre *>(entity.get());
+        if (!clean_input_string(entity_pre->language_)) {
+          LOG(WARNING) << "Wrong language in entity: \"" << entity_pre->language_ << '"';
+          entity_pre->language_.clear();
+        }
+        if (entity_pre->language_.empty()) {
+          entities.emplace_back(MessageEntity::Type::Pre, entity_pre->offset_, entity_pre->length_);
+        } else {
+          entities.emplace_back(MessageEntity::Type::PreCode, entity_pre->offset_, entity_pre->length_,
+                                std::move(entity_pre->language_));
+        }
+        break;
+      }
+      case secret_api::messageEntityTextUrl::ID: {
+        auto entity_text_url = static_cast<secret_api::messageEntityTextUrl *>(entity.get());
+        if (!clean_input_string(entity_text_url->url_)) {
+          LOG(WARNING) << "Wrong URL entity: \"" << entity_text_url->url_ << '"';
+          continue;
+        }
+        auto r_http_url = parse_url(entity_text_url->url_);
+        if (r_http_url.is_error()) {
+          LOG(WARNING) << "Wrong URL entity: \"" << entity_text_url->url_ << "\": " << r_http_url.error().message();
+          continue;
+        }
+        entities.emplace_back(MessageEntity::Type::TextUrl, entity_text_url->offset_, entity_text_url->length_,
+                              r_http_url.ok().get_url());
+        break;
+      }
+      case secret_api::messageEntityMentionName::ID:
+        // skip all name mentions in secret chats
+        break;
+      default:
+        UNREACHABLE();
+    }
+  }
+  return entities;
+}
+
+Status fix_formatted_text(string &text, vector<MessageEntity> &entities, bool allow_empty, bool skip_new_entities,
+                          bool skip_bot_commands, bool for_draft) {
+  if (!check_utf8(text)) {
+    return Status::Error(400, "Strings must be encoded in UTF-8");
+  }
+
+  fix_entities(entities);
+
+  bool in_entity = false;
+  bool has_non_space_in_entity = false;
+  size_t current_entity = 0;
+  int32 skipped_before_current_entity = 0;
+  size_t left_entities = 0;  // will remove all entities containing spaces only
+
+  int32 utf16_offset = 0;
+  int32 utf16_skipped = 0;
+
+  size_t text_size = text.size();
+  size_t last_non_space_pos = text_size + 1;
+  int32 last_non_space_utf16_offset = 0;
+
+  string result;
+  result.reserve(text_size);
+  for (size_t pos = 0; pos <= text_size; pos++) {
+    auto c = static_cast<unsigned char>(text[pos]);
+    bool is_utf8_character_begin = is_utf8_character_first_code_unit(c);
+    if (is_utf8_character_begin) {
+      if (in_entity) {
+        CHECK(current_entity < entities.size());
+        if (utf16_offset >= entities[current_entity].offset + entities[current_entity].length) {
+          if (utf16_offset != entities[current_entity].offset + entities[current_entity].length) {
+            CHECK(utf16_offset == entities[current_entity].offset + entities[current_entity].length + 1);
+            return Status::Error(16, PSLICE() << "Entity beginning at UTF-16 offset " << entities[current_entity].offset
+                                              << " ends in a middle of a UTF-16 symbol at byte offset " << pos);
+          }
+          entities[current_entity].offset -= skipped_before_current_entity;
+          entities[current_entity].length -= utf16_skipped - skipped_before_current_entity;
+          in_entity = false;
+
+          if (has_non_space_in_entity) {
+            // TODO check entities for validness, for example, that mentions, hashtags, cashtags and URLs are valid
+            if (current_entity != left_entities) {
+              entities[left_entities] = std::move(entities[current_entity]);
+            }
+            left_entities++;
+          }
+          current_entity++;
+        }
+      }
+      if (!in_entity && current_entity < entities.size() && utf16_offset >= entities[current_entity].offset) {
+        if (utf16_offset != entities[current_entity].offset) {
+          CHECK(utf16_offset == entities[current_entity].offset + 1);
+          return Status::Error(16, PSLICE() << "Entity begins in a middle of a UTF-16 symbol at byte offset " << pos);
+        }
+        in_entity = true;
+        has_non_space_in_entity = false;
+        skipped_before_current_entity = utf16_skipped;
+      }
+    }
+    if (pos == text_size) {
+      break;
+    }
+
+    switch (c) {
+      // remove control characters
+      case 0:
+      case 1:
+      case 2:
+      case 3:
+      case 4:
+      case 5:
+      case 6:
+      case 7:
+      case 8:
+      case 9:
+      // allow '\n'
+      case 11:
+      case 12:
+      // ignore '\r'
+      case 14:
+      case 15:
+      case 16:
+      case 17:
+      case 18:
+      case 19:
+      case 20:
+      case 21:
+      case 22:
+      case 23:
+      case 24:
+      case 25:
+      case 26:
+      case 27:
+      case 28:
+      case 29:
+      case 30:
+      case 31:
+      case 32:
+        result.push_back(' ');
+        utf16_offset++;
+        break;
+      case '\r':
+        // skip
+        utf16_offset++;
+        utf16_skipped++;
+        break;
+      default:
+        if (is_utf8_character_begin) {
+          utf16_offset += 1 + (c >= 0xf0);  // >= 4 bytes in symbol => surrogaite pair
+        }
+        if (c == 0xe2 && pos + 2 < text_size) {
+          unsigned char next = static_cast<unsigned char>(text[pos + 1]);
+          if (next == 0x80) {
+            next = static_cast<unsigned char>(text[pos + 2]);
+            if (0xa8 <= next && next <= 0xae) {
+              pos += 2;
+              utf16_skipped++;
+              break;
+            }
+          }
+        }
+        if (c == 0xcc && pos + 1 < text_size) {
+          unsigned char next = static_cast<unsigned char>(text[pos + 1]);
+          // remove vertical lines
+          if (next == 0xb3 || next == 0xbf || next == 0x8a) {
+            pos++;
+            utf16_skipped++;
+            break;
+          }
+        }
+
+        result.push_back(text[pos]);
+
+        if (c != '\n') {
+          has_non_space_in_entity = true;
+          last_non_space_pos = result.size();
+          last_non_space_utf16_offset = utf16_offset - utf16_skipped;
+        }
+        break;
+    }
+  }
+  entities.erase(entities.begin() + left_entities, entities.end());
+
+  if (last_non_space_pos == text_size + 1) {
+    if (allow_empty) {
+      text.clear();
+      entities.clear();
+      return Status::OK();
+    }
+    return Status::Error(3, "Message must be non-empty");
+  }
+
+  if (for_draft) {
+    text = std::move(result);
+  } else {
+    // rtrim
+    result.resize(last_non_space_pos);
+    for (auto &entity : entities) {
+      if (entity.offset + entity.length > last_non_space_utf16_offset) {
+        entity.length = last_non_space_utf16_offset - entity.offset;
+        CHECK(entity.length > 0);
+      }
+    }
+
+    // ltrim
+    size_t first_non_spaces_pos = 0;
+    size_t first_entity_begin_pos = entities.empty() ? result.size() : entities[0].offset;
+    while (first_non_spaces_pos < first_entity_begin_pos &&
+           (result[first_non_spaces_pos] == ' ' || result[first_non_spaces_pos] == '\n')) {
+      first_non_spaces_pos++;
+    }
+    if (first_non_spaces_pos > 0) {
+      int32 offset = narrow_cast<int32>(first_non_spaces_pos);
+      text = result.substr(first_non_spaces_pos);
+      for (auto &entity : entities) {
+        entity.offset -= offset;
+        CHECK(entity.offset >= 0);
+      }
+    } else {
+      text = std::move(result);
+    }
+  }
+
+  if (!allow_empty && is_empty_string(text)) {
+    return Status::Error(3, "Message must be non-empty");
+  }
+
+  constexpr size_t LENGTH_LIMIT = 35000;  // server side limit
+  if (text.size() > LENGTH_LIMIT) {
+    size_t new_size = LENGTH_LIMIT;
+    while (!is_utf8_character_first_code_unit(text[new_size])) {
+      new_size--;
+    }
+    text.resize(new_size);
+    while (!entities.empty() && entities.back().offset + entities.back().length > 8192) {
+      entities.pop_back();
+    }
+  }
+
+  if (!skip_new_entities) {
+    entities = merge_entities(std::move(entities), find_entities(text, skip_bot_commands));
+  }
+
+  for (auto it = entities.begin(); it != entities.end(); ++it) {
+    CHECK(it->length > 0);
+    if (it + 1 != entities.end()) {
+      CHECK(it->offset + it->length <= (it + 1)->offset);
+    }
+  }
+
+  // TODO MAX_MESSAGE_LENGTH and MAX_CAPTION_LENGTH
+
+  return Status::OK();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/MessageEntity.h b/libs/tdlib/td/td/telegram/MessageEntity.h
new file mode 100644
index 0000000000..871af94f7f
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/MessageEntity.h
@@ -0,0 +1,176 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/UserId.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tl_helpers.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include <tuple>
+#include <unordered_set>
+#include <utility>
+
+namespace td {
+
+class ContactsManager;
+
+class MessageEntity {
+  tl_object_ptr<td_api::TextEntityType> get_text_entity_type_object() const;
+
+ public:
+  enum class Type : int32 {
+    Mention,
+    Hashtag,
+    BotCommand,
+    Url,
+    EmailAddress,
+    Bold,
+    Italic,
+    Code,
+    Pre,
+    PreCode,
+    TextUrl,
+    MentionName,
+    Cashtag,
+    PhoneNumber
+  };
+  Type type;
+  int32 offset;
+  int32 length;
+  string argument;
+  UserId user_id;
+
+  MessageEntity() = default;
+
+  MessageEntity(Type type, int32 offset, int32 length, string argument = "")
+      : type(type), offset(offset), length(length), argument(std::move(argument)), user_id() {
+  }
+  MessageEntity(int32 offset, int32 length, UserId user_id)
+      : type(Type::MentionName), offset(offset), length(length), argument(), user_id(user_id) {
+  }
+
+  tl_object_ptr<td_api::textEntity> get_text_entity_object() const;
+
+  bool operator==(const MessageEntity &other) const {
+    return offset == other.offset && length == other.length && type == other.type && argument == other.argument &&
+           user_id == other.user_id;
+  }
+
+  bool operator<(const MessageEntity &other) const {
+    return std::tie(offset, length, type) < std::tie(other.offset, other.length, other.type);
+  }
+
+  bool operator!=(const MessageEntity &rhs) const {
+    return !(*this == rhs);
+  }
+
+  // TODO move to hpp
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    using td::store;
+    store(type, storer);
+    store(offset, storer);
+    store(length, storer);
+    if (type == Type::PreCode || type == Type::TextUrl) {
+      store(argument, storer);
+    }
+    if (type == Type::MentionName) {
+      store(user_id, storer);
+    }
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    using td::parse;
+    parse(type, parser);
+    parse(offset, parser);
+    parse(length, parser);
+    if (type == Type::PreCode || type == Type::TextUrl) {
+      parse(argument, parser);
+    }
+    if (type == Type::MentionName) {
+      parse(user_id, parser);
+    }
+  }
+};
+
+StringBuilder &operator<<(StringBuilder &string_builder, const MessageEntity &message_entity);
+
+struct FormattedText {
+  string text;
+  vector<MessageEntity> entities;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(text, storer);
+    td::store(entities, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(text, parser);
+    td::parse(entities, parser);
+  }
+};
+
+inline bool operator==(const FormattedText &lhs, const FormattedText &rhs) {
+  return lhs.text == rhs.text && lhs.entities == rhs.entities;
+}
+
+inline bool operator!=(const FormattedText &lhs, const FormattedText &rhs) {
+  return !(lhs == rhs);
+}
+
+const std::unordered_set<Slice, SliceHash> &get_valid_short_usernames();
+
+Result<vector<MessageEntity>> get_message_entities(const ContactsManager *contacts_manager,
+                                                   const vector<tl_object_ptr<td_api::textEntity>> &input_entities);
+
+vector<tl_object_ptr<td_api::textEntity>> get_text_entities_object(const vector<MessageEntity> &entities);
+
+td_api::object_ptr<td_api::formattedText> get_formatted_text_object(const FormattedText &text);
+
+vector<MessageEntity> find_entities(Slice text, bool skip_bot_commands, bool only_urls = false);
+
+vector<Slice> find_mentions(Slice str);
+vector<Slice> find_bot_commands(Slice str);
+vector<Slice> find_hashtags(Slice str);
+vector<Slice> find_cashtags(Slice str);
+bool is_email_address(Slice str);
+vector<std::pair<Slice, bool>> find_urls(Slice str);  // slice + is_email_address
+
+string get_first_url(Slice text, const vector<MessageEntity> &entities);
+
+Result<vector<MessageEntity>> parse_markdown(string &text);
+
+Result<vector<MessageEntity>> parse_html(string &text);
+
+vector<tl_object_ptr<telegram_api::MessageEntity>> get_input_message_entities(const ContactsManager *contacts_manager,
+                                                                              const vector<MessageEntity> &entities);
+
+vector<tl_object_ptr<secret_api::MessageEntity>> get_input_secret_message_entities(
+    const vector<MessageEntity> &entities);
+
+vector<MessageEntity> get_message_entities(const ContactsManager *contacts_manager,
+                                           vector<tl_object_ptr<telegram_api::MessageEntity>> &&server_entities,
+                                           const char *source);
+
+vector<MessageEntity> get_message_entities(vector<tl_object_ptr<secret_api::MessageEntity>> &&secret_entities);
+
+// like clean_input_string but also validates entities
+Status fix_formatted_text(string &text, vector<MessageEntity> &entities, bool allow_empty, bool skip_new_entities,
+                          bool skip_bot_commands, bool for_draft) TD_WARN_UNUSED_RESULT;
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/MessageId.h b/libs/tdlib/td/td/telegram/MessageId.h
new file mode 100644
index 0000000000..4af1075579
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/MessageId.h
@@ -0,0 +1,225 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/DialogId.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tl_helpers.h"
+
+#include <functional>
+#include <limits>
+#include <type_traits>
+
+namespace td {
+
+class ServerMessageId {
+  int32 id = 0;
+
+ public:
+  ServerMessageId() = default;
+
+  explicit ServerMessageId(int32 message_id) : id(message_id) {
+  }
+  template <class T, typename = std::enable_if_t<std::is_convertible<T, int32>::value>>
+  ServerMessageId(T message_id) = delete;
+
+  bool is_valid() const {
+    return id > 0;
+  }
+
+  int32 get() const {
+    return id;
+  }
+
+  bool operator==(const ServerMessageId &other) const {
+    return id == other.id;
+  }
+
+  bool operator!=(const ServerMessageId &other) const {
+    return id != other.id;
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    storer.store_int(id);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    id = parser.fetch_int();
+  }
+};
+
+class MessageId {
+  int64 id = 0;
+
+ public:
+  static constexpr int32 SERVER_ID_SHIFT = 20;
+  static constexpr int32 TYPE_MASK = (1 << 3) - 1;
+  static constexpr int32 FULL_TYPE_MASK = (1 << SERVER_ID_SHIFT) - 1;
+  static constexpr int32 TYPE_YET_UNSENT = 1;
+  static constexpr int32 TYPE_LOCAL = 2;
+
+  MessageId() = default;
+
+  explicit MessageId(ServerMessageId server_message_id)
+      : id(static_cast<int64>(server_message_id.get()) << SERVER_ID_SHIFT) {
+  }
+
+  explicit constexpr MessageId(int64 message_id) : id(message_id) {
+  }
+  template <class T, typename = std::enable_if_t<std::is_convertible<T, int64>::value>>
+  MessageId(T message_id) = delete;
+
+  static constexpr MessageId min() {
+    return MessageId(static_cast<int64>(MessageId::TYPE_LOCAL));
+  }
+  static constexpr MessageId max() {
+    return MessageId(static_cast<int64>(std::numeric_limits<int32>::max()) << SERVER_ID_SHIFT);
+  }
+
+  bool is_valid() const {
+    if (id <= 0 || id > max().get()) {
+      return false;
+    }
+    if ((id & FULL_TYPE_MASK) == 0) {
+      return true;
+    }
+    int32 type = (id & TYPE_MASK);
+    return type == TYPE_YET_UNSENT || type == TYPE_LOCAL;
+  }
+
+  int64 get() const {
+    return id;
+  }
+
+  bool is_yet_unsent() const {
+    CHECK(is_valid());
+    return (id & TYPE_MASK) == TYPE_YET_UNSENT;
+  }
+
+  bool is_local() const {
+    CHECK(is_valid());
+    return (id & TYPE_MASK) == TYPE_LOCAL;
+  }
+
+  bool is_server() const {
+    CHECK(is_valid());
+    return (id & FULL_TYPE_MASK) == 0;
+  }
+
+  ServerMessageId get_server_message_id() const {
+    CHECK(id == 0 || is_server());
+    return ServerMessageId(narrow_cast<int32>(id >> SERVER_ID_SHIFT));
+  }
+
+  // returns smallest server message id not less than this message id
+  MessageId get_next_server_message_id() const {
+    return MessageId((id + FULL_TYPE_MASK) & ~FULL_TYPE_MASK);
+  }
+
+  bool operator==(const MessageId &other) const {
+    return id == other.id;
+  }
+
+  bool operator!=(const MessageId &other) const {
+    return id != other.id;
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    storer.store_long(id);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    id = parser.fetch_long();
+  }
+};
+
+struct MessageIdHash {
+  std::size_t operator()(MessageId message_id) const {
+    return std::hash<int64>()(message_id.get());
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &string_builder, MessageId message_id) {
+  if (!message_id.is_valid()) {
+    return string_builder << "invalid message " << message_id.get();
+  }
+  if (message_id.is_server()) {
+    return string_builder << "server message " << (message_id.get() >> MessageId::SERVER_ID_SHIFT);
+  }
+  if (message_id.is_local()) {
+    return string_builder << "local message " << (message_id.get() >> MessageId::SERVER_ID_SHIFT) << '.'
+                          << (message_id.get() & MessageId::FULL_TYPE_MASK);
+  }
+  if (message_id.is_yet_unsent()) {
+    return string_builder << "yet unsent message " << (message_id.get() >> MessageId::SERVER_ID_SHIFT) << '.'
+                          << (message_id.get() & MessageId::FULL_TYPE_MASK);
+  }
+  return string_builder << "bugged message " << message_id.get();
+}
+
+struct FullMessageId {
+ private:
+  DialogId dialog_id;
+  MessageId message_id;
+
+ public:
+  FullMessageId() : dialog_id(), message_id() {
+  }
+
+  FullMessageId(DialogId dialog_id, MessageId message_id) : dialog_id(dialog_id), message_id(message_id) {
+  }
+
+  bool operator==(const FullMessageId &other) const {
+    return dialog_id == other.dialog_id && message_id == other.message_id;
+  }
+
+  bool operator!=(const FullMessageId &other) const {
+    return !(*this == other);
+  }
+
+  DialogId get_dialog_id() const {
+    return dialog_id;
+  }
+  MessageId get_message_id() const {
+    return message_id;
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    using ::td::store;
+    store(dialog_id, storer);
+    store(message_id, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    using ::td::parse;
+    parse(dialog_id, parser);
+    parse(message_id, parser);
+  }
+};
+
+struct FullMessageIdHash {
+  std::size_t operator()(FullMessageId full_message_id) const {
+    return DialogIdHash()(full_message_id.get_dialog_id()) * 2023654985u +
+           MessageIdHash()(full_message_id.get_message_id());
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &string_builder, FullMessageId full_message_id) {
+  return string_builder << full_message_id.get_message_id() << " in " << full_message_id.get_dialog_id();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/MessagesDb.cpp b/libs/tdlib/td/td/telegram/MessagesDb.cpp
new file mode 100644
index 0000000000..8ada08bfab
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/MessagesDb.cpp
@@ -0,0 +1,1006 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/MessagesDb.h"
+
+#include "td/telegram/logevent/LogEvent.h"
+#include "td/telegram/Version.h"
+
+#include "td/db/SqliteDb.h"
+#include "td/db/SqliteStatement.h"
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Slice.h"
+#include "td/utils/StackAllocator.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/Time.h"
+#include "td/utils/tl_helpers.h"
+#include "td/utils/unicode.h"
+#include "td/utils/utf8.h"
+
+#include <algorithm>
+#include <array>
+#include <iterator>
+#include <limits>
+#include <tuple>
+
+namespace td {
+
+static constexpr int32 MESSAGES_DB_INDEX_COUNT = 30;
+static constexpr int32 MESSAGES_DB_INDEX_COUNT_OLD = 9;
+
+// NB: must happen inside a transaction
+Status init_messages_db(SqliteDb &db, int32 version) {
+  LOG(INFO) << "Init message db " << tag("version", version);
+
+  // Check if database exists
+  TRY_RESULT(has_table, db.has_table("messages"));
+  if (!has_table) {
+    version = 0;
+  } else if (version < static_cast<int32>(DbVersion::DialogDbCreated) || version > current_db_version()) {
+    TRY_STATUS(drop_messages_db(db, version));
+    version = 0;
+  }
+
+  auto add_media_indices = [&db](int begin, int end) {
+    for (int i = begin; i < end; i++) {
+      TRY_STATUS(db.exec(PSLICE() << "CREATE INDEX IF NOT EXISTS message_index_" << i
+                                  << " ON messages (dialog_id, message_id) WHERE (index_mask & " << (1 << i)
+                                  << ") != 0"));
+    }
+    return Status::OK();
+  };
+
+  auto add_fts = [&db] {
+    TRY_STATUS(
+        db.exec("CREATE INDEX IF NOT EXISTS message_by_search_id ON messages "
+                "(search_id) WHERE search_id IS NOT NULL"));
+
+    TRY_STATUS(
+        db.exec("CREATE VIRTUAL TABLE IF NOT EXISTS messages_fts USING fts5(text, content='messages', "
+                "content_rowid='search_id', tokenize = \"unicode61 remove_diacritics 0 tokenchars '\a'\")"));
+    TRY_STATUS(db.exec(
+        "CREATE TRIGGER IF NOT EXISTS trigger_fts_delete BEFORE DELETE ON messages WHEN OLD.search_id IS NOT NULL"
+        " BEGIN INSERT INTO messages_fts(messages_fts, rowid, text) VALUES(\'delete\', OLD.search_id, OLD.text); END"));
+    TRY_STATUS(db.exec(
+        "CREATE TRIGGER IF NOT EXISTS trigger_fts_insert AFTER INSERT ON messages WHEN NEW.search_id IS NOT NULL"
+        " BEGIN INSERT INTO messages_fts(rowid, text) VALUES(NEW.search_id, NEW.text); END"));
+    //TRY_STATUS(db.exec(
+    //"CREATE TRIGGER IF NOT EXISTS trigger_fts_update AFTER UPDATE ON messages WHEN NEW.search_id IS NOT NULL OR "
+    //"OLD.search_id IS NOT NULL"
+    //" BEGIN "
+    //"INSERT INTO messages_fts(messages_fts, rowid, text) VALUES(\'delete\', OLD.search_id, OLD.text); "
+    //"INSERT INTO messages_fts(rowid, text) VALUES(NEW.search_id, NEW.text); "
+    //" END"));
+
+    return Status::OK();
+  };
+  auto add_call_index = [&db]() {
+    for (int i = static_cast<int>(SearchMessagesFilter::Call) - 1;
+         i < static_cast<int>(SearchMessagesFilter::MissedCall); i++) {
+      TRY_STATUS(db.exec(PSLICE() << "CREATE INDEX IF NOT EXISTS full_message_index_" << i
+                                  << " ON messages (unique_message_id) WHERE (index_mask & " << (1 << i) << ") != 0"));
+    }
+    return Status::OK();
+  };
+
+  if (version == 0) {
+    LOG(INFO) << "Create new messages db";
+    TRY_STATUS(
+        db.exec("CREATE TABLE IF NOT EXISTS messages (dialog_id INT8, message_id INT8, "
+                "unique_message_id INT4, sender_user_id INT4, random_id INT8, data BLOB, "
+                "ttl_expires_at INT4, index_mask INT4, search_id INT8, text STRING, PRIMARY KEY "
+                "(dialog_id, message_id))"));
+
+    TRY_STATUS(
+        db.exec("CREATE INDEX IF NOT EXISTS message_by_random_id ON messages (dialog_id, random_id) "
+                "WHERE random_id IS NOT NULL"));
+    TRY_STATUS(
+        db.exec("CREATE INDEX IF NOT EXISTS message_by_unique_message_id ON messages "
+                "(unique_message_id) WHERE unique_message_id IS NOT NULL"));
+
+    TRY_STATUS(
+        db.exec("CREATE INDEX IF NOT EXISTS message_by_ttl ON messages "
+                "(ttl_expires_at) WHERE ttl_expires_at IS NOT NULL"));
+
+    TRY_STATUS(add_media_indices(0, MESSAGES_DB_INDEX_COUNT));
+
+    TRY_STATUS(add_fts());
+
+    TRY_STATUS(add_call_index());
+
+    version = current_db_version();
+  }
+  if (version < static_cast<int32>(DbVersion::MessagesDbMediaIndex)) {
+    TRY_STATUS(db.exec("ALTER TABLE messages ADD COLUMN index_mask INT4"));
+    TRY_STATUS(add_media_indices(0, MESSAGES_DB_INDEX_COUNT_OLD));
+  }
+  if (version < static_cast<int32>(DbVersion::MessagesDb30MediaIndex)) {
+    TRY_STATUS(add_media_indices(MESSAGES_DB_INDEX_COUNT_OLD, MESSAGES_DB_INDEX_COUNT));
+  }
+  if (version < static_cast<int32>(DbVersion::MessagesDbFts)) {
+    TRY_STATUS(db.exec("ALTER TABLE messages ADD COLUMN search_id INT8"));
+    TRY_STATUS(db.exec("ALTER TABLE messages ADD COLUMN text STRING"));
+    TRY_STATUS(add_fts());
+  }
+  if (version < static_cast<int32>(DbVersion::MessagesCallIndex)) {
+    TRY_STATUS(add_call_index());
+  }
+  return Status::OK();
+}
+
+// NB: must happen inside a transaction
+Status drop_messages_db(SqliteDb &db, int32 version) {
+  LOG(WARNING) << "Drop messages db " << tag("version", version) << tag("current_db_version", current_db_version());
+  return db.exec("DROP TABLE IF EXISTS messages");
+}
+
+class MessagesDbImpl : public MessagesDbSyncInterface {
+ public:
+  explicit MessagesDbImpl(SqliteDb db) : db_(std::move(db)) {
+    init().ensure();
+  }
+
+  Status init() {
+    TRY_RESULT(add_message_stmt,
+               db_.get_statement("INSERT OR REPLACE INTO messages VALUES(?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, ?9, ?10)"));
+    TRY_RESULT(delete_message_stmt, db_.get_statement("DELETE FROM messages WHERE dialog_id = ?1 AND message_id = ?2"));
+    TRY_RESULT(delete_all_dialog_messages_stmt,
+               db_.get_statement("DELETE FROM messages WHERE dialog_id = ?1 AND message_id <= ?2"));
+    TRY_RESULT(delete_dialog_messages_from_user_stmt,
+               db_.get_statement("DELETE FROM messages WHERE dialog_id = ?1 AND sender_user_id == ?2"));
+
+    TRY_RESULT(get_message_stmt,
+               db_.get_statement("SELECT data FROM messages WHERE dialog_id = ?1 AND message_id = ?2"));
+    TRY_RESULT(get_message_by_random_id_stmt,
+               db_.get_statement("SELECT data FROM messages WHERE dialog_id = ?1 AND random_id = ?2"));
+    TRY_RESULT(get_message_by_unique_message_id_stmt,
+               db_.get_statement("SELECT dialog_id, data FROM messages WHERE unique_message_id = ?1"));
+
+    TRY_RESULT(get_expiring_messages_stmt,
+               db_.get_statement("SELECT dialog_id, data FROM messages WHERE ?1 < ttl_expires_at AND ttl_expires_at <= "
+                                 "?2"));
+    TRY_RESULT(get_expiring_messages_helper_stmt,
+               db_.get_statement("SELECT MAX(ttl_expires_at), COUNT(*) FROM (SELECT ttl_expires_at FROM messages WHERE "
+                                 "?1 < ttl_expires_at LIMIT ?2) AS T"));
+
+    TRY_RESULT(get_messages_asc_stmt,
+               db_.get_statement("SELECT data, message_id FROM messages WHERE dialog_id = ?1 AND "
+                                 "message_id > ?2 ORDER BY message_id ASC LIMIT ?3"));
+    TRY_RESULT(get_messages_desc_stmt, db_.get_statement("SELECT data, message_id FROM messages WHERE dialog_id = ?1 "
+                                                         "AND message_id < ?2 ORDER BY message_id DESC LIMIT ?3"));
+    TRY_RESULT(
+        get_messages_fts_stmt,
+        db_.get_statement("SELECT dialog_id, data, search_id FROM messages WHERE search_id IN (SELECT rowid FROM "
+                          "messages_fts WHERE messages_fts MATCH ?1 AND rowid < ?2 ORDER BY rowid DESC LIMIT "
+                          "?3) ORDER BY search_id DESC"));
+
+    for (int32 i = 0; i < MESSAGES_DB_INDEX_COUNT; i++) {
+      TRY_RESULT(get_messages_from_index_desc_stmt,
+                 db_.get_statement(PSLICE() << "SELECT data, message_id FROM messages WHERE dialog_id = ?1 "
+                                               "AND message_id < ?2 AND (index_mask & "
+                                            << (1 << i) << ") != 0 ORDER BY message_id DESC LIMIT ?3"));
+      get_messages_from_index_stmts_[i].desc_stmt_ = std::move(get_messages_from_index_desc_stmt);
+
+      TRY_RESULT(get_messages_from_index_asc_stmt,
+                 db_.get_statement(PSLICE() << "SELECT data, message_id FROM messages WHERE dialog_id = ?1 "
+                                               "AND message_id > ?2 AND (index_mask & "
+                                            << (1 << i) << ") != 0 ORDER BY message_id ASC LIMIT ?3"));
+      get_messages_from_index_stmts_[i].asc_stmt_ = std::move(get_messages_from_index_asc_stmt);
+
+      // LOG(ERROR) << get_messages_from_index_stmts_[i].explain().ok();
+    }
+
+    for (int i = static_cast<int>(SearchMessagesFilter::Call) - 1, pos = 0;
+         i < static_cast<int>(SearchMessagesFilter::MissedCall); i++, pos++) {
+      TRY_RESULT(get_messages_from_index_stmt,
+                 db_.get_statement(PSLICE() << "SELECT dialog_id, data FROM messages "
+                                               "WHERE unique_message_id < ?1 AND (index_mask & "
+                                            << (1 << i) << ") != 0 ORDER BY unique_message_id DESC LIMIT ?2"));
+      get_calls_stmts_[pos] = std::move(get_messages_from_index_stmt);
+      // LOG(ERROR) << get_messages_from_index_stmts_[i].explain().ok();
+    }
+
+    add_message_stmt_ = std::move(add_message_stmt);
+    delete_message_stmt_ = std::move(delete_message_stmt);
+    delete_all_dialog_messages_stmt_ = std::move(delete_all_dialog_messages_stmt);
+    delete_dialog_messages_from_user_stmt_ = std::move(delete_dialog_messages_from_user_stmt);
+
+    get_message_stmt_ = std::move(get_message_stmt);
+    get_message_by_random_id_stmt_ = std::move(get_message_by_random_id_stmt);
+    get_message_by_unique_message_id_stmt_ = std::move(get_message_by_unique_message_id_stmt);
+
+    get_expiring_messages_stmt_ = std::move(get_expiring_messages_stmt);
+    get_expiring_messages_helper_stmt_ = std::move(get_expiring_messages_helper_stmt);
+
+    get_messages_stmt_.asc_stmt_ = std::move(get_messages_asc_stmt);
+    get_messages_stmt_.desc_stmt_ = std::move(get_messages_desc_stmt);
+
+    get_messages_fts_stmt_ = std::move(get_messages_fts_stmt);
+
+    // LOG(ERROR) << get_message_stmt_.explain().ok();
+    // LOG(ERROR) << get_message_by_random_id_stmt_.explain().ok();
+    // LOG(ERROR) << get_message_by_unique_message_id_stmt_.explain().ok();
+
+    // LOG(ERROR) << get_expiring_messages_stmt_.explain().ok();
+    // LOG(ERROR) << get_expiring_messages_helper_stmt_.explain().ok();
+
+    // LOG(ERROR) << get_messages_asc_stmt_.explain().ok();
+    // LOG(ERROR) << get_messages_desc_stmt_.explain().ok();
+    // LOG(FATAL) << "EXPLAINED";
+
+    return Status::OK();
+  }
+
+  Status add_message(FullMessageId full_message_id, ServerMessageId unique_message_id, UserId sender_user_id,
+                     int64 random_id, int32 ttl_expires_at, int32 index_mask, int64 search_id, string text,
+                     BufferSlice data) override {
+    LOG(INFO) << "Add " << full_message_id << " to database";
+    auto dialog_id = full_message_id.get_dialog_id();
+    auto message_id = full_message_id.get_message_id();
+    CHECK(dialog_id.is_valid());
+    CHECK(message_id.is_valid());
+    SCOPE_EXIT {
+      add_message_stmt_.reset();
+    };
+    add_message_stmt_.bind_int64(1, dialog_id.get()).ensure();
+    add_message_stmt_.bind_int64(2, message_id.get()).ensure();
+
+    if (unique_message_id.is_valid()) {
+      add_message_stmt_.bind_int32(3, unique_message_id.get()).ensure();
+    } else {
+      add_message_stmt_.bind_null(3).ensure();
+    }
+
+    if (sender_user_id.is_valid()) {
+      add_message_stmt_.bind_int32(4, sender_user_id.get()).ensure();
+    } else {
+      add_message_stmt_.bind_null(4).ensure();
+    }
+
+    if (random_id != 0) {
+      add_message_stmt_.bind_int64(5, random_id).ensure();
+    } else {
+      add_message_stmt_.bind_null(5).ensure();
+    }
+
+    add_message_stmt_.bind_blob(6, data.as_slice()).ensure();
+
+    if (ttl_expires_at != 0) {
+      add_message_stmt_.bind_int32(7, ttl_expires_at).ensure();
+    } else {
+      add_message_stmt_.bind_null(7).ensure();
+    }
+
+    if (index_mask != 0) {
+      add_message_stmt_.bind_int32(8, index_mask).ensure();
+    } else {
+      add_message_stmt_.bind_null(8).ensure();
+    }
+    if (search_id != 0) {
+      // add dialog_id to text
+      text += PSTRING() << " \a" << dialog_id.get();
+      if (index_mask) {
+        for (int i = 0; i < MESSAGES_DB_INDEX_COUNT; i++) {
+          if ((index_mask & (1 << i))) {
+            text += PSTRING() << " \a\a" << i;
+          }
+        }
+      }
+      add_message_stmt_.bind_int64(9, search_id).ensure();
+    } else {
+      text = "";
+      add_message_stmt_.bind_null(9).ensure();
+    }
+    if (!text.empty()) {
+      add_message_stmt_.bind_string(10, text).ensure();
+    } else {
+      add_message_stmt_.bind_null(10).ensure();
+    }
+
+    add_message_stmt_.step().ensure();
+
+    return Status::OK();
+  }
+
+  Status delete_message(FullMessageId full_message_id) override {
+    auto dialog_id = full_message_id.get_dialog_id();
+    auto message_id = full_message_id.get_message_id();
+    CHECK(dialog_id.is_valid());
+    CHECK(message_id.is_valid());
+    SCOPE_EXIT {
+      delete_message_stmt_.reset();
+    };
+    delete_message_stmt_.bind_int64(1, dialog_id.get()).ensure();
+    delete_message_stmt_.bind_int64(2, message_id.get()).ensure();
+    delete_message_stmt_.step().ensure();
+    return Status::OK();
+  }
+
+  Status delete_all_dialog_messages(DialogId dialog_id, MessageId from_message_id) override {
+    CHECK(dialog_id.is_valid());
+    CHECK(from_message_id.is_valid());
+    SCOPE_EXIT {
+      delete_all_dialog_messages_stmt_.reset();
+    };
+    delete_all_dialog_messages_stmt_.bind_int64(1, dialog_id.get()).ensure();
+    delete_all_dialog_messages_stmt_.bind_int64(2, from_message_id.get()).ensure();
+    auto status = delete_all_dialog_messages_stmt_.step();
+    if (status.is_error()) {
+      LOG(ERROR) << status;
+    }
+    return status;
+  }
+
+  Status delete_dialog_messages_from_user(DialogId dialog_id, UserId sender_user_id) override {
+    CHECK(dialog_id.is_valid());
+    CHECK(sender_user_id.is_valid());
+    SCOPE_EXIT {
+      delete_dialog_messages_from_user_stmt_.reset();
+    };
+    delete_dialog_messages_from_user_stmt_.bind_int64(1, dialog_id.get()).ensure();
+    delete_dialog_messages_from_user_stmt_.bind_int32(2, sender_user_id.get()).ensure();
+    delete_dialog_messages_from_user_stmt_.step().ensure();
+    return Status::OK();
+  }
+
+  Result<BufferSlice> get_message(FullMessageId full_message_id) override {
+    auto dialog_id = full_message_id.get_dialog_id();
+    auto message_id = full_message_id.get_message_id();
+    CHECK(dialog_id.is_valid());
+    CHECK(message_id.is_valid());
+
+    SCOPE_EXIT {
+      get_message_stmt_.reset();
+    };
+    get_message_stmt_.bind_int64(1, dialog_id.get()).ensure();
+    get_message_stmt_.bind_int64(2, message_id.get()).ensure();
+    get_message_stmt_.step().ensure();
+    if (!get_message_stmt_.has_row()) {
+      return Status::Error("Not found");
+    }
+    return BufferSlice(get_message_stmt_.view_blob(0));
+  }
+
+  Result<std::pair<DialogId, BufferSlice>> get_message_by_unique_message_id(
+      ServerMessageId unique_message_id) override {
+    if (!unique_message_id.is_valid()) {
+      return Status::Error("unique_message_id is invalid");
+    }
+    SCOPE_EXIT {
+      get_message_by_unique_message_id_stmt_.reset();
+    };
+    get_message_by_unique_message_id_stmt_.bind_int32(1, unique_message_id.get()).ensure();
+    get_message_by_unique_message_id_stmt_.step().ensure();
+    if (!get_message_by_unique_message_id_stmt_.has_row()) {
+      return Status::Error("Not found");
+    }
+    DialogId dialog_id(get_message_by_unique_message_id_stmt_.view_int64(0));
+    return std::make_pair(dialog_id, BufferSlice(get_message_by_unique_message_id_stmt_.view_blob(1)));
+  }
+
+  Result<BufferSlice> get_message_by_random_id(DialogId dialog_id, int64 random_id) override {
+    SCOPE_EXIT {
+      get_message_by_random_id_stmt_.reset();
+    };
+    get_message_by_random_id_stmt_.bind_int64(1, dialog_id.get()).ensure();
+    get_message_by_random_id_stmt_.bind_int64(2, random_id).ensure();
+    get_message_by_random_id_stmt_.step().ensure();
+    if (!get_message_by_random_id_stmt_.has_row()) {
+      return Status::Error("Not found");
+    }
+    return BufferSlice(get_message_by_random_id_stmt_.view_blob(0));
+  }
+
+  Result<BufferSlice> get_dialog_message_by_date(DialogId dialog_id, MessageId first_message_id,
+                                                 MessageId last_message_id, int32 date) override {
+    int64 left_message_id = first_message_id.get();
+    int64 right_message_id = last_message_id.get();
+    CHECK(left_message_id <= right_message_id) << first_message_id << " " << last_message_id;
+    TRY_RESULT(first_messages,
+               get_messages_inner(get_messages_stmt_.asc_stmt_, dialog_id.get(), left_message_id - 1, 1));
+    if (!first_messages.empty()) {
+      MessageId real_first_message_id;
+      int32 real_first_message_date;
+      std::tie(real_first_message_id, real_first_message_date) = get_message_info(first_messages[0]);
+      if (real_first_message_date <= date) {
+        // we definitely have at least one suitable message, let's do a binary search
+        left_message_id = real_first_message_id.get();
+
+        MessageId prev_found_message_id;
+        while (left_message_id <= right_message_id) {
+          auto middle_message_id = left_message_id + ((right_message_id - left_message_id) >> 1);
+          TRY_RESULT(messages, get_messages_inner(get_messages_stmt_.asc_stmt_, dialog_id.get(), middle_message_id, 1));
+
+          MessageId message_id;
+          int32 message_date = std::numeric_limits<int32>::max();
+          if (!messages.empty()) {
+            std::tie(message_id, message_date) = get_message_info(messages[0]);
+          }
+          if (message_date <= date) {
+            left_message_id = message_id.get();
+          } else {
+            right_message_id = middle_message_id - 1;
+          }
+
+          if (prev_found_message_id == message_id) {
+            // we may be very close to the result, let's check
+            TRY_RESULT(left_messages,
+                       get_messages_inner(get_messages_stmt_.asc_stmt_, dialog_id.get(), left_message_id - 1, 2));
+            CHECK(!left_messages.empty());
+            if (left_messages.size() == 1) {
+              // only one message has left, result is found
+              break;
+            }
+
+            MessageId next_message_id;
+            int32 next_message_date;
+            std::tie(next_message_id, next_message_date) = get_message_info(left_messages[1]);
+            if (next_message_date <= date) {
+              // next message has lesser date, adjusting left message
+              left_message_id = next_message_id.get();
+            } else {
+              // next message has bigger date, result is found
+              break;
+            }
+          }
+
+          prev_found_message_id = message_id;
+        }
+
+        // left_message_id is always an id of suitable message, let's return it
+        return get_message({dialog_id, MessageId(left_message_id)});
+      }
+    }
+
+    return Status::Error("Not found");
+  }
+
+  Result<std::pair<std::vector<std::pair<DialogId, BufferSlice>>, int32>> get_expiring_messages(int32 expire_from,
+                                                                                                int32 expire_till,
+                                                                                                int32 limit) override {
+    SCOPE_EXIT {
+      get_expiring_messages_stmt_.reset();
+      get_expiring_messages_helper_stmt_.reset();
+    };
+
+    std::vector<std::pair<DialogId, BufferSlice>> messages;
+    // load messages
+    if (expire_from <= expire_till) {
+      get_expiring_messages_stmt_.bind_int32(1, expire_from).ensure();
+      get_expiring_messages_stmt_.bind_int32(2, expire_till).ensure();
+      get_expiring_messages_stmt_.step().ensure();
+
+      while (get_expiring_messages_stmt_.has_row()) {
+        DialogId dialog_id(get_expiring_messages_stmt_.view_int64(0));
+        BufferSlice data(get_expiring_messages_stmt_.view_blob(1));
+        messages.push_back(std::make_pair(dialog_id, std::move(data)));
+        get_expiring_messages_stmt_.step().ensure();
+      }
+    }
+
+    // calc next expire_till
+    get_expiring_messages_helper_stmt_.bind_int32(1, expire_till).ensure();
+    get_expiring_messages_helper_stmt_.bind_int32(2, limit).ensure();
+    get_expiring_messages_helper_stmt_.step().ensure();
+    CHECK(get_expiring_messages_helper_stmt_.has_row());
+    int32 count = get_expiring_messages_helper_stmt_.view_int32(1);
+    int32 next_expire_till = -1;
+    if (count != 0) {
+      next_expire_till = get_expiring_messages_helper_stmt_.view_int32(0);
+    }
+    return std::make_pair(std::move(messages), next_expire_till);
+  }
+
+  Result<MessagesDbMessagesResult> get_messages(MessagesDbMessagesQuery query) override {
+    if (query.index_mask != 0) {
+      return get_messages_from_index(query.dialog_id, query.from_message_id, query.index_mask, query.offset,
+                                     query.limit);
+    }
+    return get_messages_impl(get_messages_stmt_, query.dialog_id, query.from_message_id, query.offset, query.limit);
+  }
+
+  static string prepare_query(Slice query) {
+    auto is_word_character = [](uint32 a) {
+      switch (get_unicode_simple_category(a)) {
+        case UnicodeSimpleCategory::Letter:
+        case UnicodeSimpleCategory::DecimalNumber:
+        case UnicodeSimpleCategory::Number:
+          return true;
+        default:
+          return a == '_';
+      }
+    };
+
+    const size_t MAX_QUERY_SIZE = 1024;
+    query.truncate(MAX_QUERY_SIZE);
+    auto buf = StackAllocator::alloc(query.size() * 4 + 100);
+    StringBuilder sb(buf.as_slice());
+    bool in_word{false};
+
+    for (auto ptr = query.ubegin(), end = query.uend(); ptr < end;) {
+      uint32 code;
+      auto code_ptr = ptr;
+      ptr = next_utf8_unsafe(ptr, &code);
+      if (is_word_character(code)) {
+        if (!in_word) {
+          in_word = true;
+          sb << "\"";
+        }
+        sb << Slice(code_ptr, ptr);
+      } else {
+        if (in_word) {
+          in_word = false;
+          sb << "\" ";
+        }
+      }
+    }
+    if (in_word) {
+      sb << "\" ";
+    }
+
+    if (sb.is_error()) {
+      LOG(ERROR) << "StringBuilder buffer overflow";
+      return "";
+    }
+
+    return sb.as_cslice().str();
+  }
+
+  Result<MessagesDbFtsResult> get_messages_fts(MessagesDbFtsQuery query) override {
+    SCOPE_EXIT {
+      get_messages_fts_stmt_.reset();
+    };
+
+    LOG(INFO) << tag("query", query.query) << query.dialog_id << tag("index_mask", query.index_mask)
+              << tag("from_search_id", query.from_search_id) << tag("limit", query.limit);
+    string words = prepare_query(query.query);
+    LOG(INFO) << tag("from", query.query) << tag("to", words);
+
+    // dialog_id kludge
+    if (query.dialog_id.is_valid()) {
+      words += PSTRING() << " \"\a" << query.dialog_id.get() << "\"";
+    }
+
+    // index_mask kludge
+    if (query.index_mask != 0) {
+      int index_i = -1;
+      for (int i = 0; i < MESSAGES_DB_INDEX_COUNT; i++) {
+        if (query.index_mask == (1 << i)) {
+          index_i = i;
+          break;
+        }
+      }
+      if (index_i == -1) {
+        return Status::Error("Union of index types is not supported");
+      }
+      words += PSTRING() << " \"\a\a" << index_i << "\"";
+    }
+
+    auto &stmt = get_messages_fts_stmt_;
+    stmt.bind_string(1, words).ensure();
+    if (query.from_search_id == 0) {
+      query.from_search_id = std::numeric_limits<int64>::max();
+    }
+    stmt.bind_int64(2, query.from_search_id).ensure();
+    stmt.bind_int32(3, query.limit).ensure();
+    MessagesDbFtsResult result;
+    auto status = stmt.step();
+    if (status.is_error()) {
+      LOG(ERROR) << status;
+      return std::move(result);
+    }
+    while (stmt.has_row()) {
+      auto dialog_id = stmt.view_int64(0);
+      auto data_slice = stmt.view_blob(1);
+      auto search_id = stmt.view_int64(2);
+      result.next_search_id = search_id;
+      result.messages.push_back(MessagesDbMessage{DialogId(dialog_id), BufferSlice(data_slice)});
+      stmt.step().ensure();
+    }
+    return std::move(result);
+  }
+
+  Result<MessagesDbMessagesResult> get_messages_from_index(DialogId dialog_id, MessageId from_message_id,
+                                                           int32 index_mask, int32 offset, int32 limit) {
+    CHECK(index_mask != 0);
+    CHECK(index_mask < (1 << MESSAGES_DB_INDEX_COUNT)) << tag("index_mask", index_mask);
+    int index_i = -1;
+    for (int i = 0; i < MESSAGES_DB_INDEX_COUNT; i++) {
+      if (index_mask == (1 << i)) {
+        index_i = i;
+        break;
+      }
+    }
+    if (index_i == -1) {
+      return Status::Error("Union is not supported");
+    }
+
+    auto &stmt = get_messages_from_index_stmts_[index_i];
+    return get_messages_impl(stmt, dialog_id, from_message_id, offset, limit);
+  }
+
+  Result<MessagesDbCallsResult> get_calls(MessagesDbCallsQuery query) override {
+    CHECK(query.index_mask != 0);
+    CHECK(query.index_mask < (1 << MESSAGES_DB_INDEX_COUNT)) << tag("index_mask", query.index_mask);
+    int index_i = -1;
+    for (int i = 0; i < MESSAGES_DB_INDEX_COUNT; i++) {
+      if (query.index_mask == (1 << i)) {
+        index_i = i;
+        break;
+      }
+    }
+    if (index_i == -1) {
+      return Status::Error("Union is not supported");
+    }
+    int32 pos;
+    if (index_i + 1 == static_cast<int>(SearchMessagesFilter::Call)) {
+      pos = 0;
+    } else if (index_i + 1 == static_cast<int>(SearchMessagesFilter::MissedCall)) {
+      pos = 1;
+    } else {
+      return Status::Error(PSLICE() << "Index_mask is not Call or MissedCall " << query.index_mask);
+    }
+
+    auto &stmt = get_calls_stmts_[pos];
+    SCOPE_EXIT {
+      stmt.reset();
+    };
+
+    stmt.bind_int32(1, query.from_unique_message_id).ensure();
+    stmt.bind_int32(2, query.limit).ensure();
+
+    MessagesDbCallsResult result;
+    stmt.step().ensure();
+    while (stmt.has_row()) {
+      auto dialog_id = stmt.view_int64(0);
+      auto data_slice = stmt.view_blob(1);
+      result.messages.push_back(MessagesDbMessage{DialogId(dialog_id), BufferSlice(data_slice)});
+      stmt.step().ensure();
+    }
+    return std::move(result);
+  }
+
+  Status begin_transaction() override {
+    return db_.begin_transaction();
+  }
+  Status commit_transaction() override {
+    return db_.commit_transaction();
+  }
+
+ private:
+  SqliteDb db_;
+
+  SqliteStatement add_message_stmt_;
+
+  SqliteStatement delete_message_stmt_;
+  SqliteStatement delete_all_dialog_messages_stmt_;
+  SqliteStatement delete_dialog_messages_from_user_stmt_;
+
+  SqliteStatement get_message_stmt_;
+  SqliteStatement get_message_by_random_id_stmt_;
+  SqliteStatement get_message_by_unique_message_id_stmt_;
+  SqliteStatement get_expiring_messages_stmt_;
+  SqliteStatement get_expiring_messages_helper_stmt_;
+
+  struct GetMessagesStmt {
+    SqliteStatement asc_stmt_;
+    SqliteStatement desc_stmt_;
+  };
+  GetMessagesStmt get_messages_stmt_;
+
+  std::array<GetMessagesStmt, MESSAGES_DB_INDEX_COUNT> get_messages_from_index_stmts_;
+  std::array<SqliteStatement, 2> get_calls_stmts_;
+
+  SqliteStatement get_messages_fts_stmt_;
+
+  Result<MessagesDbMessagesResult> get_messages_impl(GetMessagesStmt &stmt, DialogId dialog_id,
+                                                     MessageId from_message_id, int32 offset, int32 limit) {
+    CHECK(dialog_id.is_valid()) << dialog_id;
+    CHECK(from_message_id.is_valid());
+
+    auto message_id = from_message_id.get();
+
+    if (message_id >= MessageId::max().get()) {
+      message_id--;
+    }
+
+    auto left_message_id = message_id;
+    auto left_cnt = limit + offset;
+
+    auto right_message_id = message_id - 1;
+    auto right_cnt = -offset;
+
+    std::vector<BufferSlice> left;
+    std::vector<BufferSlice> right;
+
+    if (left_cnt != 0) {
+      if (right_cnt == 1 && false) {
+        left_message_id++;
+        left_cnt++;
+      }
+
+      TRY_RESULT(left_tmp, get_messages_inner(stmt.desc_stmt_, dialog_id.get(), left_message_id, left_cnt));
+      left = std::move(left_tmp);
+
+      if (right_cnt == 1 && !left.empty() && false /*get_message_id(left[0].as_slice()) == message_id*/) {
+        right_cnt = 0;
+      }
+    }
+    if (right_cnt != 0) {
+      TRY_RESULT(right_tmp, get_messages_inner(stmt.asc_stmt_, dialog_id.get(), right_message_id, right_cnt));
+      right = std::move(right_tmp);
+      std::reverse(right.begin(), right.end());
+    }
+    if (left.empty()) {
+      return MessagesDbMessagesResult{std::move(right)};
+    }
+    if (right.empty()) {
+      return MessagesDbMessagesResult{std::move(left)};
+    }
+
+    right.reserve(right.size() + left.size());
+    std::move(left.begin(), left.end(), std::back_inserter(right));
+
+    return MessagesDbMessagesResult{std::move(right)};
+  }
+
+  Result<std::vector<BufferSlice>> get_messages_inner(SqliteStatement &stmt, int64 dialog_id, int64 from_message_id,
+                                                      int32 limit) {
+    SCOPE_EXIT {
+      stmt.reset();
+    };
+    stmt.bind_int64(1, dialog_id).ensure();
+    stmt.bind_int64(2, from_message_id).ensure();
+    stmt.bind_int32(3, limit).ensure();
+
+    std::vector<BufferSlice> result;
+    stmt.step().ensure();
+    while (stmt.has_row()) {
+      auto data_slice = stmt.view_blob(0);
+      result.emplace_back(data_slice);
+      auto message_id = stmt.view_int64(1);
+      LOG(INFO) << "Load " << MessageId(message_id) << " in " << DialogId(dialog_id) << " from database";
+      stmt.step().ensure();
+    }
+    return std::move(result);
+  }
+
+  static std::tuple<MessageId, int32> get_message_info(const BufferSlice &message) {
+    LogEventParser message_date_parser(message.as_slice());
+    int32 flags;
+    td::parse(flags, message_date_parser);
+    bool has_sender = (flags >> 10) & 1;
+    MessageId message_id;
+    td::parse(message_id, message_date_parser);
+    UserId sender_user_id;
+    if (has_sender) {
+      td::parse(sender_user_id, message_date_parser);
+    }
+    int32 date;
+    td::parse(date, message_date_parser);
+    LOG(INFO) << "Load " << message_id << " sent at " << date << " by " << sender_user_id;
+    return std::make_tuple(message_id, date);
+  }
+};
+
+std::shared_ptr<MessagesDbSyncSafeInterface> create_messages_db_sync(
+    std::shared_ptr<SqliteConnectionSafe> sqlite_connection) {
+  class MessagesDbSyncSafe : public MessagesDbSyncSafeInterface {
+   public:
+    explicit MessagesDbSyncSafe(std::shared_ptr<SqliteConnectionSafe> sqlite_connection)
+        : lsls_db_([safe_connection = std::move(sqlite_connection)] {
+          return std::make_unique<MessagesDbImpl>(safe_connection->get().clone());
+        }) {
+    }
+    MessagesDbSyncInterface &get() override {
+      return *lsls_db_.get();
+    }
+
+   private:
+    LazySchedulerLocalStorage<std::unique_ptr<MessagesDbSyncInterface>> lsls_db_;
+  };
+  return std::make_shared<MessagesDbSyncSafe>(std::move(sqlite_connection));
+}
+
+class MessagesDbAsync : public MessagesDbAsyncInterface {
+ public:
+  MessagesDbAsync(std::shared_ptr<MessagesDbSyncSafeInterface> sync_db, int32 scheduler_id) {
+    impl_ = create_actor_on_scheduler<Impl>("MessagesDbActor", scheduler_id, std::move(sync_db));
+  }
+
+  void add_message(FullMessageId full_message_id, ServerMessageId unique_message_id, UserId sender_user_id,
+                   int64 random_id, int32 ttl_expires_at, int32 index_mask, int64 search_id, string text,
+                   BufferSlice data, Promise<> promise) override {
+    send_closure_later(impl_, &Impl::add_message, full_message_id, unique_message_id, sender_user_id, random_id,
+                       ttl_expires_at, index_mask, search_id, std::move(text), std::move(data), std::move(promise));
+  }
+
+  void delete_message(FullMessageId full_message_id, Promise<> promise) override {
+    send_closure_later(impl_, &Impl::delete_message, full_message_id, std::move(promise));
+  }
+  void delete_all_dialog_messages(DialogId dialog_id, MessageId from_message_id, Promise<> promise) override {
+    send_closure_later(impl_, &Impl::delete_all_dialog_messages, dialog_id, from_message_id, std::move(promise));
+  }
+  void delete_dialog_messages_from_user(DialogId dialog_id, UserId sender_user_id, Promise<> promise) override {
+    send_closure_later(impl_, &Impl::delete_dialog_messages_from_user, dialog_id, sender_user_id, std::move(promise));
+  }
+
+  void get_message(FullMessageId full_message_id, Promise<BufferSlice> promise) override {
+    send_closure_later(impl_, &Impl::get_message, full_message_id, std::move(promise));
+  }
+  void get_message_by_unique_message_id(ServerMessageId unique_message_id,
+                                        Promise<std::pair<DialogId, BufferSlice>> promise) override {
+    send_closure_later(impl_, &Impl::get_message_by_unique_message_id, unique_message_id, std::move(promise));
+  }
+  void get_message_by_random_id(DialogId dialog_id, int64 random_id, Promise<BufferSlice> promise) override {
+    send_closure_later(impl_, &Impl::get_message_by_random_id, dialog_id, random_id, std::move(promise));
+  }
+  void get_dialog_message_by_date(DialogId dialog_id, MessageId first_message_id, MessageId last_message_id, int32 date,
+                                  Promise<BufferSlice> promise) override {
+    send_closure_later(impl_, &Impl::get_dialog_message_by_date, dialog_id, first_message_id, last_message_id, date,
+                       std::move(promise));
+  }
+
+  void get_messages(MessagesDbMessagesQuery query, Promise<MessagesDbMessagesResult> promise) override {
+    send_closure_later(impl_, &Impl::get_messages, std::move(query), std::move(promise));
+  }
+  void get_calls(MessagesDbCallsQuery query, Promise<MessagesDbCallsResult> promise) override {
+    send_closure_later(impl_, &Impl::get_calls, std::move(query), std::move(promise));
+  }
+  void get_messages_fts(MessagesDbFtsQuery query, Promise<MessagesDbFtsResult> promise) override {
+    send_closure_later(impl_, &Impl::get_messages_fts, std::move(query), std::move(promise));
+  }
+  void get_expiring_messages(
+      int32 expire_from, int32 expire_till, int32 limit,
+      Promise<std::pair<std::vector<std::pair<DialogId, BufferSlice>>, int32>> promise) override {
+    send_closure_later(impl_, &Impl::get_expiring_messages, expire_from, expire_till, limit, std::move(promise));
+  }
+
+  void close(Promise<> promise) override {
+    send_closure_later(impl_, &Impl::close, std::move(promise));
+  }
+
+  void force_flush() override {
+    send_closure_later(impl_, &Impl::force_flush);
+  }
+
+ private:
+  class Impl : public Actor {
+   public:
+    explicit Impl(std::shared_ptr<MessagesDbSyncSafeInterface> sync_db_safe) : sync_db_safe_(std::move(sync_db_safe)) {
+    }
+    void add_message(FullMessageId full_message_id, ServerMessageId unique_message_id, UserId sender_user_id,
+                     int64 random_id, int32 ttl_expires_at, int32 index_mask, int64 search_id, string text,
+                     BufferSlice data, Promise<> promise) {
+      add_write_query([=, promise = std::move(promise), data = std::move(data), text = std::move(text)](Unit) mutable {
+        promise.set_result(sync_db_->add_message(full_message_id, unique_message_id, sender_user_id, random_id,
+                                                 ttl_expires_at, index_mask, search_id, std::move(text),
+                                                 std::move(data)));
+      });
+    }
+
+    void delete_message(FullMessageId full_message_id, Promise<> promise) {
+      add_write_query([=, promise = std::move(promise)](Unit) mutable {
+        promise.set_result(sync_db_->delete_message(full_message_id));
+      });
+    }
+    void delete_all_dialog_messages(DialogId dialog_id, MessageId from_message_id, Promise<> promise) {
+      add_read_query();
+      promise.set_result(sync_db_->delete_all_dialog_messages(dialog_id, from_message_id));
+    }
+    void delete_dialog_messages_from_user(DialogId dialog_id, UserId sender_user_id, Promise<> promise) {
+      add_read_query();
+      promise.set_result(sync_db_->delete_dialog_messages_from_user(dialog_id, sender_user_id));
+    }
+
+    void get_message(FullMessageId full_message_id, Promise<BufferSlice> promise) {
+      add_read_query();
+      promise.set_result(sync_db_->get_message(full_message_id));
+    }
+    void get_message_by_unique_message_id(ServerMessageId unique_message_id,
+                                          Promise<std::pair<DialogId, BufferSlice>> promise) {
+      add_read_query();
+      promise.set_result(sync_db_->get_message_by_unique_message_id(unique_message_id));
+    }
+    void get_message_by_random_id(DialogId dialog_id, int64 random_id, Promise<BufferSlice> promise) {
+      add_read_query();
+      promise.set_result(sync_db_->get_message_by_random_id(dialog_id, random_id));
+    }
+    void get_dialog_message_by_date(DialogId dialog_id, MessageId first_message_id, MessageId last_message_id,
+                                    int32 date, Promise<BufferSlice> promise) {
+      add_read_query();
+      promise.set_result(sync_db_->get_dialog_message_by_date(dialog_id, first_message_id, last_message_id, date));
+    }
+
+    void get_messages(MessagesDbMessagesQuery query, Promise<MessagesDbMessagesResult> promise) {
+      add_read_query();
+      promise.set_result(sync_db_->get_messages(std::move(query)));
+    }
+    void get_calls(MessagesDbCallsQuery query, Promise<MessagesDbCallsResult> promise) {
+      add_read_query();
+      promise.set_result(sync_db_->get_calls(std::move(query)));
+    }
+    void get_messages_fts(MessagesDbFtsQuery query, Promise<MessagesDbFtsResult> promise) {
+      add_read_query();
+      promise.set_result(sync_db_->get_messages_fts(std::move(query)));
+    }
+    void get_expiring_messages(int32 expire_from, int32 expire_till, int32 limit,
+                               Promise<std::pair<std::vector<std::pair<DialogId, BufferSlice>>, int32>> promise) {
+      add_read_query();
+      promise.set_result(sync_db_->get_expiring_messages(expire_from, expire_till, limit));
+    }
+
+    void close(Promise<> promise) {
+      do_flush();
+      sync_db_safe_.reset();
+      sync_db_ = nullptr;
+      promise.set_value(Unit());
+      stop();
+    }
+
+    void force_flush() {
+      LOG(INFO) << "MessagesDb flushed";
+      do_flush();
+    }
+
+   private:
+    std::shared_ptr<MessagesDbSyncSafeInterface> sync_db_safe_;
+    MessagesDbSyncInterface *sync_db_ = nullptr;
+
+    static constexpr size_t MAX_PENDING_QUERIES_COUNT{50};
+    static constexpr double MAX_PENDING_QUERIES_DELAY{1};
+    std::vector<Promise<>> pending_writes_;
+    double wakeup_at_ = 0;
+    template <class F>
+    void add_write_query(F &&f) {
+      pending_writes_.push_back(PromiseCreator::lambda(std::forward<F>(f), PromiseCreator::Ignore()));
+      if (pending_writes_.size() > MAX_PENDING_QUERIES_COUNT) {
+        do_flush();
+        wakeup_at_ = 0;
+      } else if (wakeup_at_ == 0) {
+        wakeup_at_ = Time::now_cached() + MAX_PENDING_QUERIES_DELAY;
+      }
+      if (wakeup_at_ != 0) {
+        set_timeout_at(wakeup_at_);
+      }
+    }
+    void add_read_query() {
+      do_flush();
+    }
+    void do_flush() {
+      if (pending_writes_.empty()) {
+        return;
+      }
+      sync_db_->begin_transaction().ensure();
+      for (auto &query : pending_writes_) {
+        query.set_value(Unit());
+      }
+      sync_db_->commit_transaction().ensure();
+      pending_writes_.clear();
+      cancel_timeout();
+    }
+    void timeout_expired() override {
+      do_flush();
+    }
+
+    void start_up() override {
+      sync_db_ = &sync_db_safe_->get();
+    }
+  };
+  ActorOwn<Impl> impl_;
+};
+
+std::shared_ptr<MessagesDbAsyncInterface> create_messages_db_async(std::shared_ptr<MessagesDbSyncSafeInterface> sync_db,
+                                                                   int32 scheduler_id) {
+  return std::make_shared<MessagesDbAsync>(std::move(sync_db), scheduler_id);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/MessagesDb.h b/libs/tdlib/td/td/telegram/MessagesDb.h
new file mode 100644
index 0000000000..86843dd59b
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/MessagesDb.h
@@ -0,0 +1,169 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/DialogId.h"
+#include "td/telegram/MessageId.h"
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/db/SqliteConnectionSafe.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/Status.h"
+
+#include <memory>
+#include <utility>
+
+namespace td {
+// append only before Size
+enum class SearchMessagesFilter {
+  Empty,
+  Animation,
+  Audio,
+  Document,
+  Photo,
+  Video,
+  VoiceNote,
+  PhotoAndVideo,
+  Url,
+  ChatPhoto,
+  Call,
+  MissedCall,
+  VideoNote,
+  VoiceAndVideoNote,
+  Mention,
+  UnreadMention,
+  Size
+};
+
+struct MessagesDbMessagesQuery {
+  DialogId dialog_id;
+  int32 index_mask{0};
+  MessageId from_message_id;
+  int32 offset{0};
+  int32 limit{100};
+};
+
+struct MessagesDbMessagesResult {
+  std::vector<BufferSlice> messages;
+};
+
+struct MessagesDbMessage {
+  DialogId dialog_id;
+  BufferSlice data;
+};
+
+struct MessagesDbFtsQuery {
+  string query;
+  DialogId dialog_id;
+  int32 index_mask{0};
+  int64 from_search_id{0};
+  int32 limit{100};
+};
+struct MessagesDbFtsResult {
+  std::vector<MessagesDbMessage> messages;
+  int64 next_search_id{1};
+};
+
+struct MessagesDbCallsQuery {
+  int32 index_mask{0};
+  int32 from_unique_message_id{0};
+  int32 limit{100};
+};
+struct MessagesDbCallsResult {
+  std::vector<MessagesDbMessage> messages;
+};
+
+class MessagesDbSyncInterface {
+ public:
+  MessagesDbSyncInterface() = default;
+  MessagesDbSyncInterface(const MessagesDbSyncInterface &) = delete;
+  MessagesDbSyncInterface &operator=(const MessagesDbSyncInterface &) = delete;
+  virtual ~MessagesDbSyncInterface() = default;
+
+  virtual Status add_message(FullMessageId full_message_id, ServerMessageId unique_message_id, UserId sender_user_id,
+                             int64 random_id, int32 ttl_expires_at, int32 index_mask, int64 search_id, string text,
+                             BufferSlice data) = 0;
+
+  virtual Status delete_message(FullMessageId full_message_id) = 0;
+  virtual Status delete_all_dialog_messages(DialogId dialog_id, MessageId from_message_id) = 0;
+  virtual Status delete_dialog_messages_from_user(DialogId dialog_id, UserId sender_user_id) = 0;
+
+  virtual Result<BufferSlice> get_message(FullMessageId full_message_id) = 0;
+  virtual Result<std::pair<DialogId, BufferSlice>> get_message_by_unique_message_id(
+      ServerMessageId unique_message_id) = 0;
+  virtual Result<BufferSlice> get_message_by_random_id(DialogId dialog_id, int64 random_id) = 0;
+  virtual Result<BufferSlice> get_dialog_message_by_date(DialogId dialog_id, MessageId first_message_id,
+                                                         MessageId last_message_id, int32 date) = 0;
+
+  virtual Result<MessagesDbMessagesResult> get_messages(MessagesDbMessagesQuery query) = 0;
+
+  virtual Result<std::pair<std::vector<std::pair<DialogId, BufferSlice>>, int32>> get_expiring_messages(
+      int32 expire_from, int32 expire_till, int32 limit) = 0;
+  virtual Result<MessagesDbCallsResult> get_calls(MessagesDbCallsQuery query) = 0;
+  virtual Result<MessagesDbFtsResult> get_messages_fts(MessagesDbFtsQuery query) = 0;
+
+  virtual Status begin_transaction() = 0;
+  virtual Status commit_transaction() = 0;
+};
+
+class MessagesDbSyncSafeInterface {
+ public:
+  MessagesDbSyncSafeInterface() = default;
+  MessagesDbSyncSafeInterface(const MessagesDbSyncSafeInterface &) = delete;
+  MessagesDbSyncSafeInterface &operator=(const MessagesDbSyncSafeInterface &) = delete;
+  virtual ~MessagesDbSyncSafeInterface() = default;
+
+  virtual MessagesDbSyncInterface &get() = 0;
+};
+
+class MessagesDbAsyncInterface {
+ public:
+  MessagesDbAsyncInterface() = default;
+  MessagesDbAsyncInterface(const MessagesDbAsyncInterface &) = delete;
+  MessagesDbAsyncInterface &operator=(const MessagesDbAsyncInterface &) = delete;
+  virtual ~MessagesDbAsyncInterface() = default;
+
+  virtual void add_message(FullMessageId full_message_id, ServerMessageId unique_message_id, UserId sender_user_id,
+                           int64 random_id, int32 ttl_expires_at, int32 index_mask, int64 search_id, string text,
+                           BufferSlice data, Promise<> promise) = 0;
+
+  virtual void delete_message(FullMessageId full_message_id, Promise<> promise) = 0;
+  virtual void delete_all_dialog_messages(DialogId dialog_id, MessageId from_message_id, Promise<> promise) = 0;
+  virtual void delete_dialog_messages_from_user(DialogId dialog_id, UserId sender_user_id, Promise<> promise) = 0;
+
+  virtual void get_message(FullMessageId full_message_id, Promise<BufferSlice> promise) = 0;
+  virtual void get_message_by_unique_message_id(ServerMessageId unique_message_id,
+                                                Promise<std::pair<DialogId, BufferSlice>> promise) = 0;
+  virtual void get_message_by_random_id(DialogId dialog_id, int64 random_id, Promise<BufferSlice> promise) = 0;
+  virtual void get_dialog_message_by_date(DialogId dialog_id, MessageId first_message_id, MessageId last_message_id,
+                                          int32 date, Promise<BufferSlice> promise) = 0;
+
+  virtual void get_messages(MessagesDbMessagesQuery query, Promise<MessagesDbMessagesResult>) = 0;
+
+  virtual void get_calls(MessagesDbCallsQuery, Promise<MessagesDbCallsResult>) = 0;
+  virtual void get_messages_fts(MessagesDbFtsQuery query, Promise<MessagesDbFtsResult> promise) = 0;
+
+  virtual void get_expiring_messages(
+      int32 expire_from, int32 expire_till, int32 limit,
+      Promise<std::pair<std::vector<std::pair<DialogId, BufferSlice>>, int32>> promise) = 0;
+
+  virtual void close(Promise<> promise) = 0;
+  virtual void force_flush() = 0;
+};
+
+Status init_messages_db(SqliteDb &db, int version) TD_WARN_UNUSED_RESULT;
+Status drop_messages_db(SqliteDb &db, int version) TD_WARN_UNUSED_RESULT;
+
+std::shared_ptr<MessagesDbSyncSafeInterface> create_messages_db_sync(
+    std::shared_ptr<SqliteConnectionSafe> sqlite_connection);
+
+std::shared_ptr<MessagesDbAsyncInterface> create_messages_db_async(std::shared_ptr<MessagesDbSyncSafeInterface> sync_db,
+                                                                   int32 scheduler_id);
+};  // namespace td
diff --git a/libs/tdlib/td/td/telegram/MessagesManager.cpp b/libs/tdlib/td/td/telegram/MessagesManager.cpp
new file mode 100644
index 0000000000..a2b603db6c
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/MessagesManager.cpp
@@ -0,0 +1,24862 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/MessagesManager.h"
+
+#include "td/telegram/secret_api.hpp"
+#include "td/telegram/td_api.hpp"
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/PromiseFuture.h"
+#include "td/actor/SleepActor.h"
+
+#include "td/db/binlog/BinlogHelper.h"
+
+#include "td/telegram/AnimationsManager.h"
+#include "td/telegram/AnimationsManager.hpp"
+#include "td/telegram/AudiosManager.h"
+#include "td/telegram/AudiosManager.hpp"
+#include "td/telegram/AuthManager.h"
+#include "td/telegram/ConfigShared.h"
+#include "td/telegram/ContactsManager.h"
+#include "td/telegram/DialogDb.h"
+#include "td/telegram/DocumentsManager.h"
+#include "td/telegram/DocumentsManager.hpp"
+#include "td/telegram/files/FileManager.h"
+#include "td/telegram/Game.h"
+#include "td/telegram/Game.hpp"
+#include "td/telegram/Global.h"
+#include "td/telegram/HashtagHints.h"
+#include "td/telegram/InlineQueriesManager.h"
+#include "td/telegram/logevent/LogEvent.h"
+#include "td/telegram/MessagesDb.h"
+#include "td/telegram/misc.h"
+#include "td/telegram/net/NetActor.h"
+#include "td/telegram/net/NetQuery.h"
+#include "td/telegram/Payments.h"
+#include "td/telegram/Payments.hpp"
+#include "td/telegram/ReplyMarkup.hpp"
+#include "td/telegram/SecretChatActor.h"
+#include "td/telegram/SecretChatsManager.h"
+#include "td/telegram/SequenceDispatcher.h"
+#include "td/telegram/StickersManager.h"
+#include "td/telegram/StickersManager.hpp"
+#include "td/telegram/Td.h"
+#include "td/telegram/TopDialogManager.h"
+#include "td/telegram/UpdatesManager.h"
+#include "td/telegram/VideoNotesManager.h"
+#include "td/telegram/VideoNotesManager.hpp"
+#include "td/telegram/VideosManager.h"
+#include "td/telegram/VideosManager.hpp"
+#include "td/telegram/VoiceNotesManager.h"
+#include "td/telegram/VoiceNotesManager.hpp"
+#include "td/telegram/WebPageId.h"
+#include "td/telegram/WebPagesManager.h"
+
+#include "td/utils/format.h"
+#include "td/utils/HttpUrl.h"
+#include "td/utils/MimeType.h"
+#include "td/utils/misc.h"
+#include "td/utils/PathView.h"
+#include "td/utils/Random.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Time.h"
+#include "td/utils/tl_helpers.h"
+#include "td/utils/tl_storers.h"
+#include "td/utils/utf8.h"
+
+#include <algorithm>
+#include <cstring>
+#include <iterator>
+#include <limits>
+#include <set>
+#include <tuple>
+#include <type_traits>
+#include <unordered_map>
+#include <unordered_set>
+#include <utility>
+
+namespace td {
+
+class NetActorOnce : public NetActor {
+  void hangup() override {
+    on_error(0, Status::Error(500, "Request aborted"));
+    stop();
+  }
+
+  void on_result_finish() override {
+    stop();
+  }
+};
+
+void dummyUpdate::store(TlStorerToString &s, const char *field_name) const {
+  s.store_class_begin(field_name, "dummyUpdate");
+  s.store_class_end();
+}
+
+class updateSentMessage : public telegram_api::Update {
+ public:
+  int64 random_id_;
+
+  MessageId message_id_;
+  int32 date_;
+
+  updateSentMessage(int64 random_id, MessageId message_id, int32 date)
+      : random_id_(random_id), message_id_(message_id), date_(date) {
+  }
+
+  static constexpr int32 ID = 1234567890;
+  int32 get_id() const override {
+    return ID;
+  }
+
+  void store(TlStorerUnsafe &s) const override {
+    UNREACHABLE();
+  }
+
+  void store(TlStorerCalcLength &s) const override {
+    UNREACHABLE();
+  }
+
+  void store(TlStorerToString &s, const char *field_name) const override {
+    s.store_class_begin(field_name, "updateSentMessage");
+    s.store_field("random_id_", random_id_);
+    s.store_field("message_id_", message_id_.get());
+    s.store_field("date_", date_);
+    s.store_class_end();
+  }
+};
+
+class GetDialogQuery : public Td::ResultHandler {
+  DialogId dialog_id_;
+
+ public:
+  void send(DialogId dialog_id) {
+    dialog_id_ = dialog_id;
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_getPeerDialogs(
+        td->messages_manager_->get_input_dialog_peers({dialog_id}, AccessRights::Read)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getPeerDialogs>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto result = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive chat: " << to_string(result);
+
+    td->contacts_manager_->on_get_chats(std::move(result->chats_));
+    td->contacts_manager_->on_get_users(std::move(result->users_));
+    td->messages_manager_->on_get_dialogs(
+        std::move(result->dialogs_), -1, std::move(result->messages_),
+        PromiseCreator::lambda([td = td, dialog_id = dialog_id_](Result<> result) {
+          if (result.is_ok()) {
+            td->messages_manager_->on_get_dialog_success(dialog_id);
+          } else {
+            if (G()->close_flag()) {
+              return;
+            }
+            td->messages_manager_->on_get_dialog_error(dialog_id, result.error(), "OnGetDialogs");
+            td->messages_manager_->on_get_dialog_fail(dialog_id, result.move_as_error());
+          }
+        }));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "GetDialogQuery");
+    td->messages_manager_->on_get_dialog_fail(dialog_id_, std::move(status));
+  }
+};
+
+class GetPinnedDialogsQuery : public NetActorOnce {
+  Promise<Unit> promise_;
+
+ public:
+  explicit GetPinnedDialogsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  NetQueryRef send(uint64 sequence_id) {
+    auto query = G()->net_query_creator().create(create_storer(telegram_api::messages_getPinnedDialogs()));
+    auto result = query.get_weak();
+    send_closure(td->messages_manager_->sequence_dispatcher_, &MultiSequenceDispatcher::send_with_callback,
+                 std::move(query), actor_shared(this), sequence_id);
+    return result;
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getPinnedDialogs>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto result = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive pinned chats: " << to_string(result);
+
+    td->contacts_manager_->on_get_chats(std::move(result->chats_));
+    td->contacts_manager_->on_get_users(std::move(result->users_));
+    std::reverse(result->dialogs_.begin(), result->dialogs_.end());
+    td->messages_manager_->on_get_dialogs(std::move(result->dialogs_), -2, std::move(result->messages_),
+                                          std::move(promise_));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+/*
+class GetDialogsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit GetDialogsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(vector<DialogId> &&dialog_ids) {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_getPeerDialogs(
+        td->messages_manager_->get_input_dialog_peers(dialog_ids, AccessRights::Read)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getPeerDialogs>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto result = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive chats: " << to_string(result);
+
+    td->contacts_manager_->on_get_chats(std::move(result->chats_));
+    td->contacts_manager_->on_get_users(std::move(result->users_));
+    td->messages_manager_->on_get_dialogs(std::move(result->dialogs_), -1, std::move(result->messages_),
+                                          std::move(promise_));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+*/
+class GetMessagesQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit GetMessagesQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(vector<tl_object_ptr<telegram_api::InputMessage>> &&message_ids) {
+    send_query(
+        G()->net_query_creator().create(create_storer(telegram_api::messages_getMessages(std::move(message_ids)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getMessages>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    // LOG(INFO) << "Receive result for GetMessagesQuery " << to_string(ptr);
+    int32 constructor_id = ptr->get_id();
+    switch (constructor_id) {
+      case telegram_api::messages_messages::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_messages>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_messages(std::move(messages->messages_), false, "get messages");
+        break;
+      }
+      case telegram_api::messages_messagesSlice::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_messagesSlice>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_messages(std::move(messages->messages_), false, "get messages slice");
+        break;
+      }
+      case telegram_api::messages_channelMessages::ID: {
+        LOG(ERROR) << "Receive channel messages in GetMessagesQuery";
+        auto messages = move_tl_object_as<telegram_api::messages_channelMessages>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_messages(std::move(messages->messages_), false, "get channel messages");
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.message() == "MESSAGE_IDS_EMPTY") {
+      promise_.set_value(Unit());
+      return;
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetChannelMessagesQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+
+ public:
+  explicit GetChannelMessagesQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, tl_object_ptr<telegram_api::InputChannel> &&input_channel,
+            vector<tl_object_ptr<telegram_api::InputMessage>> &&message_ids) {
+    channel_id_ = channel_id;
+    CHECK(input_channel != nullptr);
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::channels_getMessages(std::move(input_channel), std::move(message_ids)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_getMessages>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(DEBUG) << "Receive result for GetChannelMessagesQuery " << to_string(ptr);
+    int32 constructor_id = ptr->get_id();
+    switch (constructor_id) {
+      case telegram_api::messages_messages::ID: {
+        LOG(ERROR) << "Receive ordinary messages in GetChannelMessagesQuery";
+        auto messages = move_tl_object_as<telegram_api::messages_messages>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_messages(std::move(messages->messages_), true, "get messages");
+        break;
+      }
+      case telegram_api::messages_messagesSlice::ID: {
+        LOG(ERROR) << "Receive ordinary messages in GetChannelMessagesQuery";
+        auto messages = move_tl_object_as<telegram_api::messages_messagesSlice>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_messages(std::move(messages->messages_), true, "get messages slice");
+        break;
+      }
+      case telegram_api::messages_channelMessages::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_channelMessages>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_messages(std::move(messages->messages_), true, "get channel messages");
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.message() == "MESSAGE_IDS_EMPTY") {
+      promise_.set_value(Unit());
+      return;
+    }
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "GetChannelMessagesQuery");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetChannelPinnedMessageQuery : public Td::ResultHandler {
+  Promise<MessageId> promise_;
+  ChannelId channel_id_;
+
+ public:
+  explicit GetChannelPinnedMessageQuery(Promise<MessageId> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id) {
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    if (input_channel == nullptr) {
+      return promise_.set_error(Status::Error(6, "Can't access the chat"));
+    }
+
+    channel_id_ = channel_id;
+    vector<tl_object_ptr<telegram_api::InputMessage>> input_messages;
+    input_messages.push_back(make_tl_object<telegram_api::inputMessagePinned>());
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::channels_getMessages(std::move(input_channel), std::move(input_messages)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_getMessages>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(DEBUG) << "Receive result for GetChannelPinnedMessageQuery " << to_string(ptr);
+    int32 constructor_id = ptr->get_id();
+    switch (constructor_id) {
+      case telegram_api::messages_messages::ID:
+      case telegram_api::messages_messagesSlice::ID:
+        LOG(ERROR) << "Receive ordinary messages in GetChannelPinnedMessageQuery " << to_string(ptr);
+        return promise_.set_error(Status::Error(500, "Receive wrong request result"));
+      case telegram_api::messages_channelMessages::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_channelMessages>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        if (messages->messages_.empty()) {
+          return promise_.set_value(MessageId());
+        }
+        if (messages->messages_.size() >= 2) {
+          LOG(ERROR) << to_string(ptr);
+          return promise_.set_error(Status::Error(500, "More than 1 pinned message received"));
+        }
+        auto full_message_id = td->messages_manager_->on_get_message(std::move(messages->messages_[0]), false, true,
+                                                                     false, false, "get channel pinned messages");
+        if (full_message_id.get_dialog_id().is_valid() && full_message_id.get_dialog_id() != DialogId(channel_id_)) {
+          LOG(ERROR) << full_message_id << " " << to_string(ptr);
+          return promise_.set_error(Status::Error(500, "Receive pinned message in a wrong chat"));
+        }
+        return promise_.set_value(full_message_id.get_message_id());
+      }
+      default:
+        UNREACHABLE();
+    }
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.message() == "MESSAGE_IDS_EMPTY") {
+      promise_.set_value(MessageId());
+      return;
+    }
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "GetChannelPinnedMessageQuery");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ExportChannelMessageLinkQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+  MessageId message_id_;
+  bool for_group_;
+
+ public:
+  explicit ExportChannelMessageLinkQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, MessageId message_id, bool for_group) {
+    channel_id_ = channel_id;
+    message_id_ = message_id;
+    for_group_ = for_group;
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::channels_exportMessageLink(
+        std::move(input_channel), message_id.get_server_message_id().get(), for_group))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_exportMessageLink>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(DEBUG) << "Receive result for ExportChannelMessageLinkQuery " << to_string(ptr);
+    td->messages_manager_->on_get_public_message_link({DialogId(channel_id_), message_id_}, for_group_,
+                                                      std::move(ptr->link_), std::move(ptr->html_));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "ExportChannelMessageLinkQuery");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetDialogListQuery : public NetActorOnce {
+  Promise<Unit> promise_;
+
+ public:
+  explicit GetDialogListQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int32 offset_date, ServerMessageId offset_message_id, DialogId offset_dialog_id, int32 limit,
+            uint64 sequence_id) {
+    auto input_peer = td->messages_manager_->get_input_peer(offset_dialog_id, AccessRights::Read);
+    if (input_peer == nullptr) {
+      input_peer = make_tl_object<telegram_api::inputPeerEmpty>();
+    }
+
+    int32 flags = telegram_api::messages_getDialogs::EXCLUDE_PINNED_MASK;
+    auto query = G()->net_query_creator().create(create_storer(telegram_api::messages_getDialogs(
+        flags, false /*ignored*/, offset_date, offset_message_id.get(), std::move(input_peer), limit)));
+    send_closure(td->messages_manager_->sequence_dispatcher_, &MultiSequenceDispatcher::send_with_callback,
+                 std::move(query), actor_shared(this), sequence_id);
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getDialogs>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for GetDialogListQuery " << to_string(ptr);
+    int32 constructor_id = ptr->get_id();
+    auto promise = PromiseCreator::lambda(
+        [promise = std::move(promise_)](Result<> result) mutable { promise.set_result(std::move(result)); });
+    if (constructor_id == telegram_api::messages_dialogs::ID) {
+      auto dialogs = move_tl_object_as<telegram_api::messages_dialogs>(ptr);
+      td->contacts_manager_->on_get_chats(std::move(dialogs->chats_));
+      td->contacts_manager_->on_get_users(std::move(dialogs->users_));
+      td->messages_manager_->on_get_dialogs(std::move(dialogs->dialogs_), narrow_cast<int32>(dialogs->dialogs_.size()),
+                                            std::move(dialogs->messages_), std::move(promise));
+    } else {
+      CHECK(constructor_id == telegram_api::messages_dialogsSlice::ID);
+      auto dialogs = move_tl_object_as<telegram_api::messages_dialogsSlice>(ptr);
+      td->contacts_manager_->on_get_chats(std::move(dialogs->chats_));
+      td->contacts_manager_->on_get_users(std::move(dialogs->users_));
+      td->messages_manager_->on_get_dialogs(std::move(dialogs->dialogs_), max(dialogs->count_, 0),
+                                            std::move(dialogs->messages_), std::move(promise));
+    }
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SearchPublicDialogsQuery : public Td::ResultHandler {
+  string query_;
+
+ public:
+  void send(const string &query) {
+    query_ = query;
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::contacts_search(query, 3 /* ignored server-side */))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::contacts_search>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto dialogs = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for SearchPublicDialogsQuery " << to_string(dialogs);
+    td->contacts_manager_->on_get_chats(std::move(dialogs->chats_));
+    td->contacts_manager_->on_get_users(std::move(dialogs->users_));
+    td->messages_manager_->on_get_public_dialogs_search_result(query_, std::move(dialogs->my_results_),
+                                                               std::move(dialogs->results_));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for SearchPublicDialogsQuery: " << status;
+    td->messages_manager_->on_failed_public_dialogs_search(query_, std::move(status));
+  }
+};
+
+class GetCommonDialogsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  UserId user_id_;
+
+ public:
+  explicit GetCommonDialogsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(UserId user_id, int32 offset_chat_id, int32 limit) {
+    user_id_ = user_id;
+    LOG(INFO) << "Get common dialogs with " << user_id << " from " << offset_chat_id << " with limit " << limit;
+
+    auto input_user = td->contacts_manager_->get_input_user(user_id);
+    CHECK(input_user != nullptr);
+
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_getCommonChats(std::move(input_user), offset_chat_id, limit))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getCommonChats>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto chats_ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for GetCommonDialogsQuery " << to_string(chats_ptr);
+    int32 constructor_id = chats_ptr->get_id();
+    switch (constructor_id) {
+      case telegram_api::messages_chats::ID: {
+        auto chats = move_tl_object_as<telegram_api::messages_chats>(chats_ptr);
+        td->messages_manager_->on_get_common_dialogs(user_id_, std::move(chats->chats_),
+                                                     narrow_cast<int32>(chats->chats_.size()));
+        break;
+      }
+      case telegram_api::messages_chatsSlice::ID: {
+        auto chats = move_tl_object_as<telegram_api::messages_chatsSlice>(chats_ptr);
+        td->messages_manager_->on_get_common_dialogs(user_id_, std::move(chats->chats_), chats->count_);
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class CreateChatQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  int64 random_id_;
+
+ public:
+  explicit CreateChatQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(vector<tl_object_ptr<telegram_api::InputUser>> &&input_users, const string &title, int64 random_id) {
+    random_id_ = random_id;
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_createChat(std::move(input_users), title))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_createChat>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for createChat " << to_string(ptr);
+    td->messages_manager_->on_create_new_dialog_success(random_id_, std::move(ptr), DialogType::Chat,
+                                                        std::move(promise_));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->messages_manager_->on_create_new_dialog_fail(random_id_, std::move(status), std::move(promise_));
+  }
+};
+
+class CreateChannelQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  int64 random_id_;
+
+ public:
+  explicit CreateChannelQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(const string &title, bool is_megagroup, const string &about, int64 random_id) {
+    int32 flags = 0;
+    if (is_megagroup) {
+      flags |= telegram_api::channels_createChannel::MEGAGROUP_MASK;
+    } else {
+      flags |= telegram_api::channels_createChannel::BROADCAST_MASK;
+    }
+
+    random_id_ = random_id;
+    send_query(G()->net_query_creator().create(create_storer(
+        telegram_api::channels_createChannel(flags, false /*ignored*/, false /*ignored*/, title, about))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_createChannel>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for createChannel " << to_string(ptr);
+    td->messages_manager_->on_create_new_dialog_success(random_id_, std::move(ptr), DialogType::Channel,
+                                                        std::move(promise_));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->messages_manager_->on_create_new_dialog_fail(random_id_, std::move(status), std::move(promise_));
+  }
+};
+
+class EditDialogPhotoQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  FileId file_id_;
+  DialogId dialog_id_;
+
+ public:
+  explicit EditDialogPhotoQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(FileId file_id, DialogId dialog_id, tl_object_ptr<telegram_api::InputChatPhoto> &&input_chat_photo) {
+    CHECK(input_chat_photo != nullptr);
+    file_id_ = file_id;
+    dialog_id_ = dialog_id;
+
+    switch (dialog_id.get_type()) {
+      case DialogType::Chat:
+        send_query(G()->net_query_creator().create(create_storer(
+            telegram_api::messages_editChatPhoto(dialog_id.get_chat_id().get(), std::move(input_chat_photo)))));
+        break;
+      case DialogType::Channel: {
+        auto channel_id = dialog_id.get_channel_id();
+        auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+        CHECK(input_channel != nullptr);
+        send_query(G()->net_query_creator().create(
+            create_storer(telegram_api::channels_editPhoto(std::move(input_channel), std::move(input_chat_photo)))));
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    static_assert(std::is_same<telegram_api::messages_editChatPhoto::ReturnType,
+                               telegram_api::channels_editPhoto::ReturnType>::value,
+                  "");
+    auto result_ptr = fetch_result<telegram_api::messages_editChatPhoto>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for editDialogPhoto: " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+
+    if (file_id_.is_valid()) {
+      td->file_manager_->delete_partial_remote_location(file_id_);
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (file_id_.is_valid()) {
+      td->file_manager_->delete_partial_remote_location(file_id_);
+    }
+    td->updates_manager_->get_difference("EditDialogPhotoQuery");
+
+    if (status.message() == "CHAT_NOT_MODIFIED") {
+      if (!td->auth_manager_->is_bot()) {
+        promise_.set_value(Unit());
+        return;
+      }
+    } else {
+      td->messages_manager_->on_get_dialog_error(dialog_id_, status, "EditDialogPhotoQuery");
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class EditDialogTitleQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+
+ public:
+  explicit EditDialogTitleQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id, const string &title) {
+    dialog_id_ = dialog_id;
+    switch (dialog_id.get_type()) {
+      case DialogType::Chat:
+        send_query(G()->net_query_creator().create(
+            create_storer(telegram_api::messages_editChatTitle(dialog_id.get_chat_id().get(), title))));
+        break;
+      case DialogType::Channel: {
+        auto channel_id = dialog_id.get_channel_id();
+        auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+        CHECK(input_channel != nullptr);
+        send_query(G()->net_query_creator().create(
+            create_storer(telegram_api::channels_editTitle(std::move(input_channel), title))));
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    static_assert(std::is_same<telegram_api::messages_editChatTitle::ReturnType,
+                               telegram_api::channels_editTitle::ReturnType>::value,
+                  "");
+    auto result_ptr = fetch_result<telegram_api::messages_editChatTitle>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for editDialogTitle " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->updates_manager_->get_difference("EditDialogTitleQuery");
+
+    if (status.message() == "CHAT_NOT_MODIFIED") {
+      if (!td->auth_manager_->is_bot()) {
+        promise_.set_value(Unit());
+        return;
+      }
+    } else {
+      td->messages_manager_->on_get_dialog_error(dialog_id_, status, "EditDialogTitleQuery");
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SaveDraftMessageQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+
+ public:
+  explicit SaveDraftMessageQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id, const unique_ptr<DraftMessage> &draft_message) {
+    LOG(INFO) << "Save draft in " << dialog_id;
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Write);
+    if (input_peer == nullptr) {
+      LOG(INFO) << "Can't update draft message because have no write access to " << dialog_id;
+      return;
+    }
+
+    int32 flags = 0;
+    ServerMessageId reply_to_message_id;
+    if (draft_message != nullptr) {
+      if (draft_message->reply_to_message_id.is_valid() && draft_message->reply_to_message_id.is_server()) {
+        reply_to_message_id = draft_message->reply_to_message_id.get_server_message_id();
+        flags |= MessagesManager::SEND_MESSAGE_FLAG_IS_REPLY;
+      }
+      if (draft_message->input_message_text.disable_web_page_preview) {
+        flags |= MessagesManager::SEND_MESSAGE_FLAG_DISABLE_WEB_PAGE_PREVIEW;
+      }
+      if (draft_message->input_message_text.text.entities.size()) {
+        flags |= MessagesManager::SEND_MESSAGE_FLAG_HAS_ENTITIES;
+      }
+    }
+
+    dialog_id_ = dialog_id;
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_saveDraft(
+        flags, false /*ignored*/, reply_to_message_id.get(), std::move(input_peer),
+        draft_message == nullptr ? "" : draft_message->input_message_text.text.text,
+        draft_message == nullptr ? vector<tl_object_ptr<telegram_api::MessageEntity>>()
+                                 : get_input_message_entities(td->contacts_manager_.get(),
+                                                              draft_message->input_message_text.text.entities)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_saveDraft>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    if (!result) {
+      on_error(id, Status::Error(400, "Save draft failed"));
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (!td->messages_manager_->on_get_dialog_error(dialog_id_, status, "SaveDraftMessageQuery")) {
+      LOG(ERROR) << "Receive error for SaveDraftMessageQuery: " << status;
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ToggleDialogPinQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+  bool is_pinned_;
+
+ public:
+  explicit ToggleDialogPinQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id, bool is_pinned) {
+    dialog_id_ = dialog_id;
+    is_pinned_ = is_pinned;
+    auto input_peer = td->messages_manager_->get_input_dialog_peer(dialog_id, AccessRights::Read);
+    if (input_peer == nullptr) {
+      return;
+    }
+
+    int32 flags = 0;
+    if (is_pinned) {
+      flags |= telegram_api::messages_toggleDialogPin::PINNED_MASK;
+    }
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_toggleDialogPin(flags, false /*ignored*/, std::move(input_peer)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_toggleDialogPin>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    if (!result) {
+      on_error(id, Status::Error(400, "Toggle dialog pin failed"));
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (!td->messages_manager_->on_get_dialog_error(dialog_id_, status, "ToggleDialogPinQuery")) {
+      LOG(ERROR) << "Receive error for ToggleDialogPinQuery: " << status;
+    }
+    td->messages_manager_->on_update_dialog_pinned(dialog_id_, !is_pinned_);
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ReorderPinnedDialogsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit ReorderPinnedDialogsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(const vector<DialogId> &dialog_ids) {
+    int32 flags = telegram_api::messages_reorderPinnedDialogs::FORCE_MASK;
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_reorderPinnedDialogs(
+        flags, true /*ignored*/, td->messages_manager_->get_input_dialog_peers(dialog_ids, AccessRights::Read)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_reorderPinnedDialogs>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.move_as_ok();
+    if (!result) {
+      return on_error(id, Status::Error(400, "Result is false"));
+    }
+    LOG(INFO) << "Pinned chats reordered";
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for ReorderPinnedDialogsQuery: " << status;
+    td->messages_manager_->on_update_pinned_dialogs();
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetMessagesViewsQuery : public Td::ResultHandler {
+  DialogId dialog_id_;
+  vector<MessageId> message_ids_;
+
+ public:
+  void send(DialogId dialog_id, vector<MessageId> &&message_ids, bool increment_view_counter) {
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Read);
+    if (input_peer == nullptr) {
+      LOG(ERROR) << "Can't update message views because doesn't have info about the " << dialog_id;
+      return;
+    }
+
+    LOG(INFO) << "View " << message_ids.size() << " messages in " << dialog_id
+              << ", increment = " << increment_view_counter;
+    dialog_id_ = dialog_id;
+    message_ids_ = std::move(message_ids);
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_getMessagesViews(
+        std::move(input_peer), MessagesManager::get_server_message_ids(message_ids_), increment_view_counter))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getMessagesViews>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    vector<int32> views = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for GetMessagesViewsQuery " << format::as_array(views);
+    if (message_ids_.size() != views.size()) {
+      return on_error(id, Status::Error(500, "Wrong number of message views returned"));
+    }
+
+    for (size_t i = 0; i < message_ids_.size(); i++) {
+      td->messages_manager_->on_update_message_views({dialog_id_, message_ids_[i]}, views[i]);
+    }
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (!td->messages_manager_->on_get_dialog_error(dialog_id_, status, "GetMessagesViewsQuery")) {
+      LOG(ERROR) << "Receive error for GetMessagesViewsQuery: " << status;
+    }
+    status.ignore();
+  }
+};
+
+class ReadMessagesContentsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit ReadMessagesContentsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(vector<MessageId> &&message_ids) {
+    LOG(INFO) << "Receive ReadMessagesContentsQuery for messages " << format::as_array(message_ids);
+
+    send_query(G()->net_query_creator().create(create_storer(
+        telegram_api::messages_readMessageContents(MessagesManager::get_server_message_ids(message_ids)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_readMessageContents>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto affected_messages = result_ptr.move_as_ok();
+    CHECK(affected_messages->get_id() == telegram_api::messages_affectedMessages::ID);
+
+    if (affected_messages->pts_count_ > 0) {
+      td->messages_manager_->add_pending_update(make_tl_object<dummyUpdate>(), affected_messages->pts_,
+                                                affected_messages->pts_count_, false, "read messages content query");
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for read message contents: " << status;
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ReadChannelMessagesContentsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+
+ public:
+  explicit ReadChannelMessagesContentsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, vector<MessageId> &&message_ids) {
+    channel_id_ = channel_id;
+
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    if (input_channel == nullptr) {
+      LOG(ERROR) << "Have no input channel for " << channel_id;
+      return;
+    }
+
+    LOG(INFO) << "Receive ReadChannelMessagesContentsQuery for messages " << format::as_array(message_ids) << " in "
+              << channel_id;
+
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::channels_readMessageContents(
+        std::move(input_channel), MessagesManager::get_server_message_ids(message_ids)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_readMessageContents>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    LOG_IF(ERROR, !result) << "Read channel messages contents failed";
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (!td->contacts_manager_->on_get_channel_error(channel_id_, status, "ReadChannelMessagesContentsQuery")) {
+      LOG(ERROR) << "Receive error for read messages contents in " << channel_id_ << ": " << status;
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetDialogMessageByDateQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+  int32 date_;
+  int64 random_id_;
+
+ public:
+  explicit GetDialogMessageByDateQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id, int32 date, int64 random_id) {
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Read);
+    if (input_peer == nullptr) {
+      return promise_.set_error(Status::Error(500, "Have no info about the chat"));
+    }
+
+    dialog_id_ = dialog_id;
+    date_ = date;
+    random_id_ = random_id;
+
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_getHistory(std::move(input_peer), 0, date, -3, 5, 0, 0, 0))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getHistory>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    int32 constructor_id = ptr->get_id();
+    switch (constructor_id) {
+      case telegram_api::messages_messages::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_messages>(ptr);
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_dialog_message_by_date_success(dialog_id_, date_, random_id_,
+                                                                     std::move(messages->messages_));
+        break;
+      }
+      case telegram_api::messages_messagesSlice::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_messagesSlice>(ptr);
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_dialog_message_by_date_success(dialog_id_, date_, random_id_,
+                                                                     std::move(messages->messages_));
+        break;
+      }
+      case telegram_api::messages_channelMessages::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_channelMessages>(ptr);
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_dialog_message_by_date_success(dialog_id_, date_, random_id_,
+                                                                     std::move(messages->messages_));
+        break;
+      }
+      case telegram_api::messages_messagesNotModified::ID:
+        return on_error(id, Status::Error(500, "Server returned messagesNotModified"));
+      default:
+        UNREACHABLE();
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (!td->messages_manager_->on_get_dialog_error(dialog_id_, status, "GetDialogMessageByDateQuery")) {
+      LOG(ERROR) << "Receive error for GetDialogMessageByDateQuery in " << dialog_id_ << ": " << status;
+    }
+    promise_.set_error(std::move(status));
+    td->messages_manager_->on_get_dialog_message_by_date_fail(random_id_);
+  }
+};
+
+class GetHistoryQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+  MessageId from_message_id_;
+  int32 offset_;
+  int32 limit_;
+  bool from_the_end_;
+
+ public:
+  explicit GetHistoryQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id, MessageId from_message_id, int32 offset, int32 limit) {
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Read);
+    if (input_peer == nullptr) {
+      LOG(ERROR) << "Can't get chat history in " << dialog_id << " because doesn't have info about the chat";
+      return promise_.set_error(Status::Error(500, "Have no info about the chat"));
+    }
+    CHECK(offset < 0);
+
+    dialog_id_ = dialog_id;
+    from_message_id_ = from_message_id;
+    offset_ = offset;
+    limit_ = limit;
+    from_the_end_ = false;
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_getHistory(
+        std::move(input_peer), from_message_id.get_server_message_id().get(), 0, offset, limit, 0, 0, 0))));
+  }
+
+  void send_get_from_the_end(DialogId dialog_id, int32 limit) {
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Read);
+    if (input_peer == nullptr) {
+      LOG(ERROR) << "Can't get chat history because doesn't have info about the chat";
+      return promise_.set_error(Status::Error(500, "Have no info about the chat"));
+    }
+
+    dialog_id_ = dialog_id;
+    offset_ = 0;
+    limit_ = limit;
+    from_the_end_ = true;
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_getHistory(std::move(input_peer), 0, 0, 0, limit, 0, 0, 0))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getHistory>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    // LOG(INFO) << "Receive result for GetHistoryQuery " << to_string(ptr);
+    int32 constructor_id = ptr->get_id();
+    switch (constructor_id) {
+      case telegram_api::messages_messages::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_messages>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_history(dialog_id_, from_message_id_, offset_, limit_, from_the_end_,
+                                              std::move(messages->messages_));
+        break;
+      }
+      case telegram_api::messages_messagesSlice::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_messagesSlice>(ptr);
+        // TODO use messages->count_
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_history(dialog_id_, from_message_id_, offset_, limit_, from_the_end_,
+                                              std::move(messages->messages_));
+        break;
+      }
+      case telegram_api::messages_channelMessages::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_channelMessages>(ptr);
+        // TODO use messages->count_, messages->pts_
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_history(dialog_id_, from_message_id_, offset_, limit_, from_the_end_,
+                                              std::move(messages->messages_));
+        break;
+      }
+      case telegram_api::messages_messagesNotModified::ID:
+        LOG(ERROR) << "Receive messagesNotModified";
+        break;
+      default:
+        UNREACHABLE();
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (!td->messages_manager_->on_get_dialog_error(dialog_id_, status, "GetHistoryQuery")) {
+      LOG(ERROR) << "Receive error for getHistoryQuery in " << dialog_id_ << ": " << status;
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ReadHistoryQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+
+ public:
+  explicit ReadHistoryQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id, MessageId max_message_id) {
+    dialog_id_ = dialog_id;
+    send_query(G()->net_query_creator().create(create_storer(
+        telegram_api::messages_readHistory(td->messages_manager_->get_input_peer(dialog_id, AccessRights::Read),
+                                           max_message_id.get_server_message_id().get()))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_readHistory>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto affected_messages = result_ptr.move_as_ok();
+    CHECK(affected_messages->get_id() == telegram_api::messages_affectedMessages::ID);
+    LOG(INFO) << "Receive result for readHistory: " << to_string(affected_messages);
+
+    if (affected_messages->pts_count_ > 0) {
+      td->messages_manager_->add_pending_update(make_tl_object<dummyUpdate>(), affected_messages->pts_,
+                                                affected_messages->pts_count_, false, "read history query");
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (!td->messages_manager_->on_get_dialog_error(dialog_id_, status, "ReadHistoryQuery")) {
+      LOG(ERROR) << "Receive error for readHistory: " << status;
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ReadChannelHistoryQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+  bool allow_error_;
+
+ public:
+  explicit ReadChannelHistoryQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, MessageId max_message_id, bool allow_error) {
+    channel_id_ = channel_id;
+    allow_error_ = allow_error;
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+
+    send_query(G()->net_query_creator().create(create_storer(
+        telegram_api::channels_readHistory(std::move(input_channel), max_message_id.get_server_message_id().get()))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_readHistory>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    LOG_IF(ERROR, !result && !allow_error_) << "Read history failed";
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (!td->contacts_manager_->on_get_channel_error(channel_id_, status, "ReadChannelHistoryQuery")) {
+      LOG(ERROR) << "Receive error for readChannelHistory: " << status;
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SearchMessagesQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+  string query_;
+  UserId sender_user_id_;
+  MessageId from_message_id_;
+  int32 offset_;
+  int32 limit_;
+  SearchMessagesFilter filter_;
+  int64 random_id_;
+
+ public:
+  explicit SearchMessagesQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id, const string &query, UserId sender_user_id,
+            telegram_api::object_ptr<telegram_api::InputUser> &&sender_input_user, MessageId from_message_id,
+            int32 offset, int32 limit, SearchMessagesFilter filter, int64 random_id) {
+    auto input_peer = dialog_id.is_valid() ? td->messages_manager_->get_input_peer(dialog_id, AccessRights::Read)
+                                           : make_tl_object<telegram_api::inputPeerEmpty>();
+    if (input_peer == nullptr) {
+      LOG(ERROR) << "Can't search messages because doesn't have info about the chat";
+      return promise_.set_error(Status::Error(500, "Have no info about the chat"));
+    }
+
+    dialog_id_ = dialog_id;
+    query_ = query;
+    sender_user_id_ = sender_user_id;
+    from_message_id_ = from_message_id;
+    offset_ = offset;
+    limit_ = limit;
+    filter_ = filter;
+    random_id_ = random_id;
+
+    if (filter == SearchMessagesFilter::UnreadMention) {
+      send_query(G()->net_query_creator().create(create_storer(
+          telegram_api::messages_getUnreadMentions(std::move(input_peer), from_message_id.get_server_message_id().get(),
+                                                   offset, limit, std::numeric_limits<int32>::max(), 0))));
+    } else {
+      int32 flags = 0;
+      if (sender_input_user != nullptr) {
+        flags |= telegram_api::messages_search::FROM_ID_MASK;
+      }
+
+      send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_search(
+          flags, std::move(input_peer), query, std::move(sender_input_user),
+          MessagesManager::get_input_messages_filter(filter), 0, std::numeric_limits<int32>::max(),
+          from_message_id.get_server_message_id().get(), offset, limit, std::numeric_limits<int32>::max(), 0, 0))));
+    }
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    static_assert(std::is_same<telegram_api::messages_getUnreadMentions::ReturnType,
+                               telegram_api::messages_search::ReturnType>::value,
+                  "");
+    auto result_ptr = fetch_result<telegram_api::messages_search>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for SearchMessagesQuery: " << to_string(ptr);
+    int32 constructor_id = ptr->get_id();
+    switch (constructor_id) {
+      case telegram_api::messages_messages::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_messages>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_dialog_messages_search_result(
+            dialog_id_, query_, sender_user_id_, from_message_id_, offset_, limit_, filter_, random_id_,
+            narrow_cast<int32>(messages->messages_.size()), std::move(messages->messages_));
+        break;
+      }
+      case telegram_api::messages_messagesSlice::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_messagesSlice>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_dialog_messages_search_result(
+            dialog_id_, query_, sender_user_id_, from_message_id_, offset_, limit_, filter_, random_id_,
+            messages->count_, std::move(messages->messages_));
+        break;
+      }
+      case telegram_api::messages_channelMessages::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_channelMessages>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_dialog_messages_search_result(
+            dialog_id_, query_, sender_user_id_, from_message_id_, offset_, limit_, filter_, random_id_,
+            messages->count_, std::move(messages->messages_));
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "SearchMessagesQuery");
+    td->messages_manager_->on_failed_dialog_messages_search(dialog_id_, random_id_);
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SearchMessagesGlobalQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  string query_;
+  int32 offset_date_;
+  DialogId offset_dialog_id_;
+  MessageId offset_message_id_;
+  int32 limit_;
+  int64 random_id_;
+
+ public:
+  explicit SearchMessagesGlobalQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(const string &query, int32 offset_date, DialogId offset_dialog_id, MessageId offset_message_id, int32 limit,
+            int64 random_id) {
+    query_ = query;
+    offset_date_ = offset_date;
+    offset_dialog_id_ = offset_dialog_id;
+    offset_message_id_ = offset_message_id;
+    limit_ = limit;
+    random_id_ = random_id;
+
+    auto input_peer = td->messages_manager_->get_input_peer(offset_dialog_id, AccessRights::Read);
+    if (input_peer == nullptr) {
+      input_peer = make_tl_object<telegram_api::inputPeerEmpty>();
+    }
+
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_searchGlobal(
+        query, offset_date_, std::move(input_peer), offset_message_id.get_server_message_id().get(), limit))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_searchGlobal>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for SearchMessagesGlobalQuery: " << to_string(ptr);
+    int32 constructor_id = ptr->get_id();
+    switch (constructor_id) {
+      case telegram_api::messages_messages::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_messages>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_messages_search_result(
+            query_, offset_date_, offset_dialog_id_, offset_message_id_, limit_, random_id_,
+            narrow_cast<int32>(messages->messages_.size()), std::move(messages->messages_));
+        break;
+      }
+      case telegram_api::messages_messagesSlice::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_messagesSlice>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_messages_search_result(query_, offset_date_, offset_dialog_id_,
+                                                             offset_message_id_, limit_, random_id_, messages->count_,
+                                                             std::move(messages->messages_));
+        break;
+      }
+      case telegram_api::messages_channelMessages::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_channelMessages>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_messages_search_result(query_, offset_date_, offset_dialog_id_,
+                                                             offset_message_id_, limit_, random_id_, messages->count_,
+                                                             std::move(messages->messages_));
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->messages_manager_->on_failed_messages_search(random_id_);
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetRecentLocationsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+  int32 limit_;
+  int64 random_id_;
+
+ public:
+  explicit GetRecentLocationsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id, int32 limit, int64 random_id) {
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Read);
+    if (input_peer == nullptr) {
+      LOG(ERROR) << "Can't get recent locations because doesn't have info about the chat";
+      return promise_.set_error(Status::Error(500, "Have no info about the chat"));
+    }
+
+    dialog_id_ = dialog_id;
+    limit_ = limit;
+    random_id_ = random_id;
+
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_getRecentLocations(std::move(input_peer), limit, 0))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getRecentLocations>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for GetRecentLocationsQuery: " << to_string(ptr);
+    int32 constructor_id = ptr->get_id();
+    switch (constructor_id) {
+      case telegram_api::messages_messages::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_messages>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_recent_locations(dialog_id_, limit_, random_id_,
+                                                       narrow_cast<int32>(messages->messages_.size()),
+                                                       std::move(messages->messages_));
+        break;
+      }
+      case telegram_api::messages_messagesSlice::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_messagesSlice>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_recent_locations(dialog_id_, limit_, random_id_, messages->count_,
+                                                       std::move(messages->messages_));
+        break;
+      }
+      case telegram_api::messages_channelMessages::ID: {
+        auto messages = move_tl_object_as<telegram_api::messages_channelMessages>(ptr);
+
+        td->contacts_manager_->on_get_chats(std::move(messages->chats_));
+        td->contacts_manager_->on_get_users(std::move(messages->users_));
+        td->messages_manager_->on_get_recent_locations(dialog_id_, limit_, random_id_, messages->count_,
+                                                       std::move(messages->messages_));
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "GetRecentLocationsQuery");
+    td->messages_manager_->on_get_recent_locations_failed(random_id_);
+    promise_.set_error(std::move(status));
+  }
+};
+
+class DeleteHistoryQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+  MessageId max_message_id_;
+  bool remove_from_dialog_list_;
+
+  void send_request() {
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id_, AccessRights::Read);
+    if (input_peer == nullptr) {
+      return promise_.set_error(Status::Error(3, "Chat is not accessible"));
+    }
+
+    int32 flags = 0;
+    if (!remove_from_dialog_list_) {
+      flags |= telegram_api::messages_deleteHistory::JUST_CLEAR_MASK;
+    }
+    LOG(INFO) << "Delete " << dialog_id_ << " history up to " << max_message_id_ << " with flags " << flags;
+
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_deleteHistory(
+        flags, false /*ignored*/, std::move(input_peer), max_message_id_.get_server_message_id().get()))));
+  }
+
+ public:
+  explicit DeleteHistoryQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id, MessageId max_message_id, bool remove_from_dialog_list) {
+    dialog_id_ = dialog_id;
+    max_message_id_ = max_message_id;
+    remove_from_dialog_list_ = remove_from_dialog_list;
+
+    send_request();
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_deleteHistory>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto affected_history = result_ptr.move_as_ok();
+    CHECK(affected_history->get_id() == telegram_api::messages_affectedHistory::ID);
+
+    if (affected_history->pts_count_ > 0) {
+      td->messages_manager_->add_pending_update(make_tl_object<dummyUpdate>(), affected_history->pts_,
+                                                affected_history->pts_count_, false, "delete history query");
+    }
+
+    if (affected_history->offset_ > 0) {
+      send_request();
+      return;
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "DeleteHistoryQuery");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class DeleteChannelHistoryQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+  MessageId max_message_id_;
+  bool allow_error_;
+
+ public:
+  explicit DeleteChannelHistoryQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, MessageId max_message_id, bool allow_error) {
+    channel_id_ = channel_id;
+    max_message_id_ = max_message_id;
+    allow_error_ = allow_error;
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+
+    send_query(G()->net_query_creator().create(create_storer(
+        telegram_api::channels_deleteHistory(std::move(input_channel), max_message_id.get_server_message_id().get()))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_deleteHistory>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    LOG_IF(ERROR, !allow_error_ && !result)
+        << "Delete history in " << channel_id_ << " up to " << max_message_id_ << " failed";
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (!td->contacts_manager_->on_get_channel_error(channel_id_, status, "DeleteChannelHistoryQuery")) {
+      LOG(ERROR) << "Receive error for deleteChannelHistory: " << status;
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class DeleteUserHistoryQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+  UserId user_id_;
+
+  void send_request() {
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id_);
+    if (input_channel == nullptr) {
+      return promise_.set_error(Status::Error(3, "Chat is not accessible"));
+    }
+    auto input_user = td->contacts_manager_->get_input_user(user_id_);
+    if (input_user == nullptr) {
+      return promise_.set_error(Status::Error(3, "Usat is not accessible"));
+    }
+
+    LOG(INFO) << "Delete all messages from " << user_id_ << " in " << channel_id_;
+
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::channels_deleteUserHistory(std::move(input_channel), std::move(input_user)))));
+  }
+
+ public:
+  explicit DeleteUserHistoryQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, UserId user_id) {
+    channel_id_ = channel_id;
+    user_id_ = user_id;
+
+    send_request();
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_deleteUserHistory>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto affected_history = result_ptr.move_as_ok();
+    CHECK(affected_history->get_id() == telegram_api::messages_affectedHistory::ID);
+
+    if (affected_history->pts_count_ > 0) {
+      td->messages_manager_->add_pending_channel_update(DialogId(channel_id_), make_tl_object<dummyUpdate>(),
+                                                        affected_history->pts_, affected_history->pts_count_,
+                                                        "delete user history query");
+    }
+
+    if (affected_history->offset_ > 0) {
+      send_request();
+      return;
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "DeleteUserHistoryQuery");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ReadAllMentionsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+
+  void send_request() {
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id_, AccessRights::Read);
+    if (input_peer == nullptr) {
+      return promise_.set_error(Status::Error(3, "Chat is not accessible"));
+    }
+
+    LOG(INFO) << "Read all mentions in " << dialog_id_;
+
+    send_query(
+        G()->net_query_creator().create(create_storer(telegram_api::messages_readMentions(std::move(input_peer)))));
+  }
+
+ public:
+  explicit ReadAllMentionsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id) {
+    dialog_id_ = dialog_id;
+
+    send_request();
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_readMentions>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto affected_history = result_ptr.move_as_ok();
+    CHECK(affected_history->get_id() == telegram_api::messages_affectedHistory::ID);
+
+    if (affected_history->pts_count_ > 0) {
+      if (dialog_id_.get_type() == DialogType::Channel) {
+        LOG(ERROR) << "Receive pts_count " << affected_history->pts_count_ << " in result of ReadAllMentionsQuery in "
+                   << dialog_id_;
+        td->updates_manager_->get_difference("Wrong messages_readMentions result");
+      } else {
+        td->messages_manager_->add_pending_update(make_tl_object<dummyUpdate>(), affected_history->pts_,
+                                                  affected_history->pts_count_, false, "read all mentions query");
+      }
+    }
+
+    if (affected_history->offset_ > 0) {
+      send_request();
+      return;
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "ReadAllMentionsQuery");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SendSecretMessageActor : public NetActor {
+  int64 random_id_;
+
+ public:
+  void send(DialogId dialog_id, int64 reply_to_random_id, int32 ttl, const string &message, SecretInputMedia media,
+            vector<tl_object_ptr<secret_api::MessageEntity>> &&entities, UserId via_bot_user_id, int64 media_album_id,
+            int64 random_id) {
+    if (false && !media.empty()) {
+      td->messages_manager_->on_send_secret_message_error(random_id, Status::Error(400, "FILE_PART_1_MISSING"), Auto());
+      return;
+    }
+
+    CHECK(dialog_id.get_type() == DialogType::SecretChat);
+    random_id_ = random_id;
+
+    int32 flags = 0;
+    if (reply_to_random_id != 0) {
+      flags |= secret_api::decryptedMessage::REPLY_TO_RANDOM_ID_MASK;
+    }
+    if (via_bot_user_id.is_valid()) {
+      flags |= secret_api::decryptedMessage::VIA_BOT_NAME_MASK;
+    }
+    if (!media.empty()) {
+      flags |= secret_api::decryptedMessage::MEDIA_MASK;
+    }
+    if (!entities.empty()) {
+      flags |= secret_api::decryptedMessage::ENTITIES_MASK;
+    }
+    if (media_album_id != 0) {
+      CHECK(media_album_id < 0);
+      flags |= secret_api::decryptedMessage::GROUPED_ID_MASK;
+    }
+
+    send_closure(G()->secret_chats_manager(), &SecretChatsManager::send_message, dialog_id.get_secret_chat_id(),
+                 make_tl_object<secret_api::decryptedMessage>(
+                     flags, random_id, ttl, message, std::move(media.decrypted_media_), std::move(entities),
+                     td->contacts_manager_->get_user_username(via_bot_user_id), reply_to_random_id, -media_album_id),
+                 std::move(media.input_file_),
+                 PromiseCreator::event(self_closure(this, &SendSecretMessageActor::done)));
+  }
+
+  void done() {
+    stop();
+  }
+};
+
+class SendMessageActor : public NetActorOnce {
+  int64 random_id_;
+  DialogId dialog_id_;
+
+ public:
+  void send(int32 flags, DialogId dialog_id, MessageId reply_to_message_id,
+            tl_object_ptr<telegram_api::ReplyMarkup> &&reply_markup,
+            vector<tl_object_ptr<telegram_api::MessageEntity>> &&entities, const string &message, int64 random_id,
+            NetQueryRef *send_query_ref, uint64 sequence_dispatcher_id) {
+    random_id_ = random_id;
+    dialog_id_ = dialog_id;
+
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Write);
+    if (input_peer == nullptr) {
+      on_error(0, Status::Error(400, "Have no write access to the chat"));
+      return;
+    }
+
+    if (!entities.empty()) {
+      flags |= MessagesManager::SEND_MESSAGE_FLAG_HAS_ENTITIES;
+    }
+
+    auto query = G()->net_query_creator().create(create_storer(telegram_api::messages_sendMessage(
+        flags, false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/, std::move(input_peer),
+        reply_to_message_id.get_server_message_id().get(), message, random_id, std::move(reply_markup),
+        std::move(entities))));
+    if (G()->shared_config().get_option_boolean("use_quick_ack")) {
+      query->quick_ack_promise_ = PromiseCreator::lambda(
+          [random_id](Unit) {
+            send_closure(G()->messages_manager(), &MessagesManager::on_send_message_get_quick_ack, random_id);
+          },
+          PromiseCreator::Ignore());
+    }
+    *send_query_ref = query.get_weak();
+    query->debug("send to MessagesManager::MultiSequenceDispatcher");
+    send_closure(td->messages_manager_->sequence_dispatcher_, &MultiSequenceDispatcher::send_with_callback,
+                 std::move(query), actor_shared(this), sequence_dispatcher_id);
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_sendMessage>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for sendMessage for " << random_id_ << ": " << to_string(ptr);
+
+    auto constructor_id = ptr->get_id();
+    if (constructor_id != telegram_api::updateShortSentMessage::ID) {
+      td->messages_manager_->check_send_message_result(random_id_, dialog_id_, ptr.get(), "SendMessage");
+      return td->updates_manager_->on_get_updates(std::move(ptr));
+    }
+    auto sent_message = move_tl_object_as<telegram_api::updateShortSentMessage>(ptr);
+    td->messages_manager_->on_update_sent_text_message(random_id_, std::move(sent_message->media_),
+                                                       std::move(sent_message->entities_));
+
+    auto message_id = MessageId(ServerMessageId(sent_message->id_));
+    if (dialog_id_.get_type() == DialogType::Channel) {
+      td->messages_manager_->add_pending_channel_update(
+          dialog_id_, make_tl_object<updateSentMessage>(random_id_, message_id, sent_message->date_),
+          sent_message->pts_, sent_message->pts_count_, "send message actor");
+      return;
+    }
+
+    td->messages_manager_->add_pending_update(
+        make_tl_object<updateSentMessage>(random_id_, message_id, sent_message->date_), sent_message->pts_,
+        sent_message->pts_count_, false, "send message actor");
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for sendMessage: " << status;
+    if (G()->close_flag() && G()->parameters().use_message_db) {
+      // do not send error, message will be re-sent
+      return;
+    }
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "SendMessageActor");
+    td->messages_manager_->on_send_message_fail(random_id_, std::move(status));
+  }
+};
+
+class StartBotQuery : public Td::ResultHandler {
+  int64 random_id_;
+  DialogId dialog_id_;
+
+ public:
+  NetQueryRef send(tl_object_ptr<telegram_api::InputUser> bot_input_user, DialogId dialog_id,
+                   tl_object_ptr<telegram_api::InputPeer> input_peer, const string &parameter, int64 random_id) {
+    CHECK(bot_input_user != nullptr);
+    CHECK(input_peer != nullptr);
+    random_id_ = random_id;
+    dialog_id_ = dialog_id;
+
+    auto query = G()->net_query_creator().create(create_storer(
+        telegram_api::messages_startBot(std::move(bot_input_user), std::move(input_peer), random_id, parameter)));
+    if (G()->shared_config().get_option_boolean("use_quick_ack")) {
+      query->quick_ack_promise_ = PromiseCreator::lambda(
+          [random_id](Unit) {
+            send_closure(G()->messages_manager(), &MessagesManager::on_send_message_get_quick_ack, random_id);
+          },
+          PromiseCreator::Ignore());
+    }
+    auto send_query_ref = query.get_weak();
+    send_query(std::move(query));
+    return send_query_ref;
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_startBot>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for startBot for " << random_id_ << ": " << to_string(ptr);
+    // Result may contain messageActionChatAddUser
+    // td->messages_manager_->check_send_message_result(random_id_, dialog_id_, ptr.get(), "StartBot");
+    td->updates_manager_->on_get_updates(std::move(ptr));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for startBot: " << status;
+    if (G()->close_flag() && G()->parameters().use_message_db) {
+      // do not send error, message should be re-sent
+      return;
+    }
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "StartBotQuery");
+    td->messages_manager_->on_send_message_fail(random_id_, std::move(status));
+  }
+};
+
+class SendInlineBotResultQuery : public Td::ResultHandler {
+  int64 random_id_;
+  DialogId dialog_id_;
+
+ public:
+  NetQueryRef send(int32 flags, DialogId dialog_id, MessageId reply_to_message_id, int64 random_id, int64 query_id,
+                   const string &result_id) {
+    random_id_ = random_id;
+    dialog_id_ = dialog_id;
+
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Write);
+    CHECK(input_peer != nullptr);
+
+    auto query = G()->net_query_creator().create(create_storer(telegram_api::messages_sendInlineBotResult(
+        flags, false /*ignored*/, false /*ignored*/, false /*ignored*/, std::move(input_peer),
+        reply_to_message_id.get_server_message_id().get(), random_id, query_id, result_id)));
+    auto send_query_ref = query.get_weak();
+    send_query(std::move(query));
+    return send_query_ref;
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_sendInlineBotResult>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for sendInlineBotResult for " << random_id_ << ": " << to_string(ptr);
+    td->messages_manager_->check_send_message_result(random_id_, dialog_id_, ptr.get(), "SendInlineBotResult");
+    td->updates_manager_->on_get_updates(std::move(ptr));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for sendInlineBotResult: " << status;
+    if (G()->close_flag() && G()->parameters().use_message_db) {
+      // do not send error, message will be re-sent
+      return;
+    }
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "SendInlineBotResultQuery");
+    td->messages_manager_->on_send_message_fail(random_id_, std::move(status));
+  }
+};
+
+class SendMultiMediaActor : public NetActorOnce {
+  vector<int64> random_ids_;
+  DialogId dialog_id_;
+
+ public:
+  void send(int32 flags, DialogId dialog_id, MessageId reply_to_message_id,
+            vector<tl_object_ptr<telegram_api::inputSingleMedia>> &&input_single_media, uint64 sequence_dispatcher_id) {
+    for (auto &single_media : input_single_media) {
+      random_ids_.push_back(single_media->random_id_);
+    }
+    dialog_id_ = dialog_id;
+
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Write);
+    if (input_peer == nullptr) {
+      on_error(0, Status::Error(400, "Have no write access to the chat"));
+      return;
+    }
+
+    auto query = G()->net_query_creator().create(create_storer(telegram_api::messages_sendMultiMedia(
+        flags, false /*ignored*/, false /*ignored*/, false /*ignored*/, std::move(input_peer),
+        reply_to_message_id.get_server_message_id().get(), std::move(input_single_media))));
+    if (G()->shared_config().get_option_boolean("use_quick_ack")) {
+      query->quick_ack_promise_ = PromiseCreator::lambda(
+          [random_ids = random_ids_](Unit) {
+            for (auto random_id : random_ids) {
+              send_closure(G()->messages_manager(), &MessagesManager::on_send_message_get_quick_ack, random_id);
+            }
+          },
+          PromiseCreator::Ignore());
+    }
+    query->debug("send to MessagesManager::MultiSequenceDispatcher");
+    send_closure(td->messages_manager_->sequence_dispatcher_, &MultiSequenceDispatcher::send_with_callback,
+                 std::move(query), actor_shared(this), sequence_dispatcher_id);
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_sendMultiMedia>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for sendMultiMedia for " << format::as_array(random_ids_) << ": " << to_string(ptr);
+
+    auto sent_random_ids = td->updates_manager_->get_sent_messages_random_ids(ptr.get());
+    bool is_result_wrong = false;
+    auto sent_random_ids_size = sent_random_ids.size();
+    for (auto &random_id : random_ids_) {
+      auto it = sent_random_ids.find(random_id);
+      if (it == sent_random_ids.end()) {
+        if (random_ids_.size() == 1) {
+          is_result_wrong = true;
+        }
+        td->messages_manager_->on_send_message_fail(random_id, Status::Error(400, "Message was not sent"));
+      } else {
+        sent_random_ids.erase(it);
+      }
+    }
+    if (!sent_random_ids.empty()) {
+      is_result_wrong = true;
+    }
+    if (!is_result_wrong) {
+      auto sent_messages = td->updates_manager_->get_new_messages(ptr.get());
+      if (sent_random_ids_size != sent_messages.size()) {
+        is_result_wrong = true;
+      }
+      for (auto &sent_message : sent_messages) {
+        if (td->messages_manager_->get_message_dialog_id(*sent_message) != dialog_id_) {
+          is_result_wrong = true;
+        }
+      }
+    }
+    if (is_result_wrong) {
+      LOG(ERROR) << "Receive wrong result for sendMultiMedia with random_ids " << format::as_array(random_ids_)
+                 << " to " << dialog_id_ << ": " << oneline(to_string(ptr));
+      td->updates_manager_->schedule_get_difference("Wrong sendMultiMedia result");
+    }
+
+    td->updates_manager_->on_get_updates(std::move(ptr));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for sendMultiMedia: " << status;
+    if (G()->close_flag() && G()->parameters().use_message_db) {
+      // do not send error, message will be re-sent
+      return;
+    }
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "SendMultiMediaActor");
+    for (auto &random_id : random_ids_) {
+      td->messages_manager_->on_send_message_fail(random_id, status.clone());
+    }
+  }
+};
+
+class SendMediaActor : public NetActorOnce {
+  int64 random_id_;
+  FileId file_id_;
+  FileId thumbnail_file_id_;
+  DialogId dialog_id_;
+
+ public:
+  void send(FileId file_id, FileId thumbnail_file_id, int32 flags, DialogId dialog_id, MessageId reply_to_message_id,
+            tl_object_ptr<telegram_api::ReplyMarkup> &&reply_markup,
+            vector<tl_object_ptr<telegram_api::MessageEntity>> &&entities, const string &message,
+            tl_object_ptr<telegram_api::InputMedia> &&input_media, int64 random_id, NetQueryRef *send_query_ref,
+            uint64 sequence_dispatcher_id) {
+    random_id_ = random_id;
+    file_id_ = file_id;
+    thumbnail_file_id_ = thumbnail_file_id;
+    dialog_id_ = dialog_id;
+
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Write);
+    if (input_peer == nullptr) {
+      on_error(0, Status::Error(400, "Have no write access to the chat"));
+      return;
+    }
+    if (!entities.empty()) {
+      flags |= telegram_api::messages_sendMedia::ENTITIES_MASK;
+    }
+
+    telegram_api::messages_sendMedia request(flags, false /*ignored*/, false /*ignored*/, false /*ignored*/,
+                                             std::move(input_peer), reply_to_message_id.get_server_message_id().get(),
+                                             std::move(input_media), message, random_id, std::move(reply_markup),
+                                             std::move(entities));
+    LOG(INFO) << "Send media: " << to_string(request);
+    auto query = G()->net_query_creator().create(create_storer(request));
+    if (G()->shared_config().get_option_boolean("use_quick_ack")) {
+      query->quick_ack_promise_ = PromiseCreator::lambda(
+          [random_id](Unit) {
+            send_closure(G()->messages_manager(), &MessagesManager::on_send_message_get_quick_ack, random_id);
+          },
+          PromiseCreator::Ignore());
+    }
+    *send_query_ref = query.get_weak();
+    query->debug("send to MessagesManager::MultiSequenceDispatcher");
+    send_closure(td->messages_manager_->sequence_dispatcher_, &MultiSequenceDispatcher::send_with_callback,
+                 std::move(query), actor_shared(this), sequence_dispatcher_id);
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_sendMedia>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    if (thumbnail_file_id_.is_valid()) {
+      // always delete partial remote location for the thumbnail, because it can't be reused anyway
+      // TODO delete it only in the case it can't be merged with file thumbnail
+      td->file_manager_->delete_partial_remote_location(thumbnail_file_id_);
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for sendMedia for " << random_id_ << ": " << to_string(ptr);
+    td->messages_manager_->check_send_message_result(random_id_, dialog_id_, ptr.get(), "SendMedia");
+    td->updates_manager_->on_get_updates(std::move(ptr));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for sendMedia: " << status;
+    if (G()->close_flag() && G()->parameters().use_message_db) {
+      // do not send error, message will be re-sent
+      return;
+    }
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "SendMediaActor");
+    if (file_id_.is_valid()) {
+      if (begins_with(status.message(), "FILE_PART_") && ends_with(status.message(), "_MISSING")) {
+        td->messages_manager_->on_send_message_file_part_missing(random_id_,
+                                                                 to_integer<int32>(status.message().substr(10)));
+        return;
+      } else {
+        if (status.code() != 429 && status.code() < 500 && !G()->close_flag()) {
+          td->file_manager_->delete_partial_remote_location(file_id_);
+        }
+      }
+    }
+    if (thumbnail_file_id_.is_valid()) {
+      // always delete partial remote location for the thumbnail, because it can't be reused anyway
+      td->file_manager_->delete_partial_remote_location(thumbnail_file_id_);
+    }
+    td->messages_manager_->on_send_message_fail(random_id_, std::move(status));
+  }
+};
+
+class UploadMediaQuery : public Td::ResultHandler {
+  DialogId dialog_id_;
+  MessageId message_id_;
+  FileId file_id_;
+  FileId thumbnail_file_id_;
+
+ public:
+  void send(DialogId dialog_id, MessageId message_id, FileId file_id, FileId thumbnail_file_id,
+            tl_object_ptr<telegram_api::InputMedia> &&input_media) {
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Write);
+    if (input_peer == nullptr) {
+      on_error(0, Status::Error(400, "Have no write access to the chat"));
+      return;
+    }
+    CHECK(input_media != nullptr);
+
+    dialog_id_ = dialog_id;
+    message_id_ = message_id;
+    file_id_ = file_id;
+    thumbnail_file_id_ = thumbnail_file_id;
+
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_uploadMedia(std::move(input_peer), std::move(input_media)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_uploadMedia>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for uploadMedia: " << to_string(ptr);
+    td->messages_manager_->on_upload_message_media_success(dialog_id_, message_id_, std::move(ptr));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(WARNING) << "Receive error for uploadMedia: " << status;
+    if (G()->close_flag() && G()->parameters().use_message_db) {
+      // do not send error, message will be re-sent
+      return;
+    }
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "UploadMediaQuery");
+    if (file_id_.is_valid()) {
+      if (begins_with(status.message(), "FILE_PART_") && ends_with(status.message(), "_MISSING")) {
+        td->messages_manager_->on_upload_message_media_file_part_missing(
+            dialog_id_, message_id_, to_integer<int32>(status.message().substr(10)));
+        return;
+      } else {
+        if (status.code() != 429 && status.code() < 500 && !G()->close_flag()) {
+          td->file_manager_->delete_partial_remote_location(file_id_);
+        }
+      }
+    }
+    td->messages_manager_->on_upload_message_media_fail(dialog_id_, message_id_, std::move(status));
+  }
+};
+
+class EditMessageActor : public NetActorOnce {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+
+ public:
+  explicit EditMessageActor(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int32 flags, DialogId dialog_id, MessageId message_id, const string &message,
+            vector<tl_object_ptr<telegram_api::MessageEntity>> &&entities,
+            tl_object_ptr<telegram_api::InputGeoPoint> &&input_geo_point,
+            tl_object_ptr<telegram_api::ReplyMarkup> &&reply_markup, uint64 sequence_dispatcher_id) {
+    dialog_id_ = dialog_id;
+
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Edit);
+    if (input_peer == nullptr) {
+      on_error(0, Status::Error(400, "Can't access the chat"));
+      return;
+    }
+
+    if (reply_markup != nullptr) {
+      flags |= MessagesManager::SEND_MESSAGE_FLAG_HAS_REPLY_MARKUP;
+    }
+    if (!entities.empty()) {
+      flags |= MessagesManager::SEND_MESSAGE_FLAG_HAS_ENTITIES;
+    }
+    if (!message.empty()) {
+      flags |= MessagesManager::SEND_MESSAGE_FLAG_HAS_MESSAGE;
+    }
+    if (input_geo_point != nullptr) {
+      flags |= telegram_api::messages_editMessage::GEO_POINT_MASK;
+    }
+    LOG(DEBUG) << "Edit message with flags " << flags;
+
+    auto query = G()->net_query_creator().create(create_storer(telegram_api::messages_editMessage(
+        flags, false /*ignored*/, false /*ignored*/, std::move(input_peer), message_id.get_server_message_id().get(),
+        message, std::move(reply_markup), std::move(entities), std::move(input_geo_point))));
+
+    query->debug("send to MessagesManager::MultiSequenceDispatcher");
+    send_closure(td->messages_manager_->sequence_dispatcher_, &MultiSequenceDispatcher::send_with_callback,
+                 std::move(query), actor_shared(this), sequence_dispatcher_id);
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_editMessage>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for editMessage: " << to_string(ptr);
+    if (ptr->get_id() == telegram_api::updateShortSentMessage::ID) {
+      LOG(ERROR) << "Receive updateShortSentMessage in edit message";
+      return on_error(id, Status::Error(500, "Unsupported result was returned from the server"));
+    }
+
+    td->updates_manager_->on_get_updates(std::move(ptr));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for editMessage: " << status;
+    if (!td->auth_manager_->is_bot() && status.message() == "MESSAGE_NOT_MODIFIED") {
+      return promise_.set_value(Unit());
+    }
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "EditMessageActor");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class EditInlineMessageQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit EditInlineMessageQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int32 flags, tl_object_ptr<telegram_api::inputBotInlineMessageID> input_bot_inline_message_id,
+            const string &message, vector<tl_object_ptr<telegram_api::MessageEntity>> &&entities,
+            tl_object_ptr<telegram_api::InputGeoPoint> &&input_geo_point,
+            tl_object_ptr<telegram_api::ReplyMarkup> &&reply_markup) {
+    CHECK(input_bot_inline_message_id != nullptr);
+
+    if (reply_markup != nullptr) {
+      flags |= MessagesManager::SEND_MESSAGE_FLAG_HAS_REPLY_MARKUP;
+    }
+    if (!entities.empty()) {
+      flags |= MessagesManager::SEND_MESSAGE_FLAG_HAS_ENTITIES;
+    }
+    if (!message.empty()) {
+      flags |= MessagesManager::SEND_MESSAGE_FLAG_HAS_MESSAGE;
+    }
+    if (input_geo_point != nullptr) {
+      flags |= telegram_api::messages_editInlineBotMessage::GEO_POINT_MASK;
+    }
+    LOG(DEBUG) << "Edit inline message with flags " << flags;
+
+    auto dc_id = DcId::internal(input_bot_inline_message_id->dc_id_);
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_editInlineBotMessage(
+            flags, false /*ignored*/, false /*ignored*/, std::move(input_bot_inline_message_id), message,
+            std::move(reply_markup), std::move(entities), std::move(input_geo_point))),
+        dc_id));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_editInlineBotMessage>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    LOG_IF(ERROR, !result_ptr.ok()) << "Receive false in result of editInlineMessage";
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for editInlineMessage: " << status;
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SetGameScoreActor : public NetActorOnce {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+
+ public:
+  explicit SetGameScoreActor(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id, MessageId message_id, bool edit_message,
+            tl_object_ptr<telegram_api::InputUser> input_user, int32 score, bool force, uint64 sequence_dispatcher_id) {
+    int32 flags = 0;
+    if (edit_message) {
+      flags |= telegram_api::messages_setGameScore::EDIT_MESSAGE_MASK;
+    }
+    if (force) {
+      flags |= telegram_api::messages_setGameScore::FORCE_MASK;
+    }
+
+    dialog_id_ = dialog_id;
+
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Edit);
+    if (input_peer == nullptr) {
+      on_error(0, Status::Error(400, "Can't access the chat"));
+      return;
+    }
+
+    CHECK(input_user != nullptr);
+    auto query = G()->net_query_creator().create(create_storer(
+        telegram_api::messages_setGameScore(flags, false /*ignored*/, false /*ignored*/, std::move(input_peer),
+                                            message_id.get_server_message_id().get(), std::move(input_user), score)));
+
+    LOG(INFO) << "Set game score to " << score;
+
+    query->debug("send to MessagesManager::MultiSequenceDispatcher");
+    send_closure(td->messages_manager_->sequence_dispatcher_, &MultiSequenceDispatcher::send_with_callback,
+                 std::move(query), actor_shared(this), sequence_dispatcher_id);
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_setGameScore>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for setGameScore: " << to_string(ptr);
+    td->updates_manager_->on_get_updates(std::move(ptr));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for setGameScore: " << status;
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "SetGameScoreActor");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SetInlineGameScoreQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit SetInlineGameScoreQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(tl_object_ptr<telegram_api::inputBotInlineMessageID> input_bot_inline_message_id, bool edit_message,
+            tl_object_ptr<telegram_api::InputUser> input_user, int32 score, bool force) {
+    CHECK(input_bot_inline_message_id != nullptr);
+    CHECK(input_user != nullptr);
+
+    int32 flags = 0;
+    if (edit_message) {
+      flags |= telegram_api::messages_setInlineGameScore::EDIT_MESSAGE_MASK;
+    }
+    if (force) {
+      flags |= telegram_api::messages_setInlineGameScore::FORCE_MASK;
+    }
+
+    LOG(INFO) << "Set inline game score to " << score;
+    auto dc_id = DcId::internal(input_bot_inline_message_id->dc_id_);
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_setInlineGameScore(flags, false /*ignored*/, false /*ignored*/,
+                                                                std::move(input_bot_inline_message_id),
+                                                                std::move(input_user), score)),
+        dc_id));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_setInlineGameScore>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    LOG_IF(ERROR, !result_ptr.ok()) << "Receive false in result of setInlineGameScore";
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for setInlineGameScore: " << status;
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetGameHighScoresQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+  int64 random_id_;
+
+ public:
+  explicit GetGameHighScoresQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id, MessageId message_id, tl_object_ptr<telegram_api::InputUser> input_user,
+            int64 random_id) {
+    dialog_id_ = dialog_id;
+    random_id_ = random_id;
+
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Read);
+    CHECK(input_peer != nullptr);
+
+    CHECK(input_user != nullptr);
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_getGameHighScores(
+        std::move(input_peer), message_id.get_server_message_id().get(), std::move(input_user)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getGameHighScores>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->messages_manager_->on_get_game_high_scores(random_id_, result_ptr.move_as_ok());
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for getGameHighScores: " << status;
+    td->messages_manager_->on_get_game_high_scores(random_id_, nullptr);
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "GetGameHighScoresQuery");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetInlineGameHighScoresQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  int64 random_id_;
+
+ public:
+  explicit GetInlineGameHighScoresQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(tl_object_ptr<telegram_api::inputBotInlineMessageID> input_bot_inline_message_id,
+            tl_object_ptr<telegram_api::InputUser> input_user, int64 random_id) {
+    CHECK(input_bot_inline_message_id != nullptr);
+    CHECK(input_user != nullptr);
+
+    random_id_ = random_id;
+
+    auto dc_id = DcId::internal(input_bot_inline_message_id->dc_id_);
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_getInlineGameHighScores(
+                                                   std::move(input_bot_inline_message_id), std::move(input_user))),
+                                               dc_id));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getInlineGameHighScores>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->messages_manager_->on_get_game_high_scores(random_id_, result_ptr.move_as_ok());
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for getInlineGameHighScores: " << status;
+    td->messages_manager_->on_get_game_high_scores(random_id_, nullptr);
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ForwardMessagesActor : public NetActorOnce {
+  Promise<Unit> promise_;
+  vector<int64> random_ids_;
+  DialogId to_dialog_id_;
+
+ public:
+  explicit ForwardMessagesActor(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int32 flags, DialogId to_dialog_id, DialogId from_dialog_id, const vector<MessageId> &message_ids,
+            vector<int64> &&random_ids, uint64 sequence_dispatcher_id) {
+    LOG(INFO) << "Forward " << format::as_array(message_ids) << " from " << from_dialog_id << " to " << to_dialog_id;
+
+    random_ids_ = random_ids;
+    to_dialog_id_ = to_dialog_id;
+
+    auto to_input_peer = td->messages_manager_->get_input_peer(to_dialog_id, AccessRights::Write);
+    if (to_input_peer == nullptr) {
+      on_error(0, Status::Error(400, "Have no write access to the chat"));
+      return;
+    }
+
+    auto from_input_peer = td->messages_manager_->get_input_peer(from_dialog_id, AccessRights::Read);
+    if (from_input_peer == nullptr) {
+      on_error(0, Status::Error(400, "Can't access the chat to forward messages from"));
+      return;
+    }
+
+    auto query = G()->net_query_creator().create(create_storer(telegram_api::messages_forwardMessages(
+        flags, false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/, std::move(from_input_peer),
+        MessagesManager::get_server_message_ids(message_ids), std::move(random_ids), std::move(to_input_peer))));
+    if (G()->shared_config().get_option_boolean("use_quick_ack")) {
+      query->quick_ack_promise_ = PromiseCreator::lambda(
+          [random_ids = random_ids_](Unit) {
+            for (auto random_id : random_ids) {
+              send_closure(G()->messages_manager(), &MessagesManager::on_send_message_get_quick_ack, random_id);
+            }
+          },
+          PromiseCreator::Ignore());
+    }
+    send_closure(td->messages_manager_->sequence_dispatcher_, &MultiSequenceDispatcher::send_with_callback,
+                 std::move(query), actor_shared(this), sequence_dispatcher_id);
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_forwardMessages>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for forwardMessages for " << format::as_array(random_ids_) << ": " << to_string(ptr);
+    auto sent_random_ids = td->updates_manager_->get_sent_messages_random_ids(ptr.get());
+    bool is_result_wrong = false;
+    auto sent_random_ids_size = sent_random_ids.size();
+    for (auto &random_id : random_ids_) {
+      auto it = sent_random_ids.find(random_id);
+      if (it == sent_random_ids.end()) {
+        if (random_ids_.size() == 1) {
+          is_result_wrong = true;
+        }
+        td->messages_manager_->on_send_message_fail(random_id, Status::Error(400, "Message was not forwarded"));
+      } else {
+        sent_random_ids.erase(it);
+      }
+    }
+    if (!sent_random_ids.empty()) {
+      is_result_wrong = true;
+    }
+    if (!is_result_wrong) {
+      auto sent_messages = td->updates_manager_->get_new_messages(ptr.get());
+      if (sent_random_ids_size != sent_messages.size()) {
+        is_result_wrong = true;
+      }
+      for (auto &sent_message : sent_messages) {
+        if (td->messages_manager_->get_message_dialog_id(*sent_message) != to_dialog_id_) {
+          is_result_wrong = true;
+        }
+      }
+    }
+    if (is_result_wrong) {
+      LOG(ERROR) << "Receive wrong result for forwarding messages with random_ids " << format::as_array(random_ids_)
+                 << " to " << to_dialog_id_ << ": " << oneline(to_string(ptr));
+      td->updates_manager_->schedule_get_difference("Wrong forwardMessages result");
+    }
+
+    td->updates_manager_->on_get_updates(std::move(ptr));
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for forward messages: " << status;
+    if (G()->close_flag() && G()->parameters().use_message_db) {
+      // do not send error, messages should be re-sent
+      return;
+    }
+    // no on_get_dialog_error call, because two dialogs are involved
+    for (auto &random_id : random_ids_) {
+      td->messages_manager_->on_send_message_fail(random_id, status.clone());
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SendScreenshotNotificationQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  int64 random_id_;
+  DialogId dialog_id_;
+
+ public:
+  explicit SendScreenshotNotificationQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id, int64 random_id) {
+    random_id_ = random_id;
+    dialog_id_ = dialog_id;
+
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Write);
+    CHECK(input_peer != nullptr);
+
+    auto query = G()->net_query_creator().create(
+        create_storer(telegram_api::messages_sendScreenshotNotification(std::move(input_peer), 0, random_id)));
+    send_query(std::move(query));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_sendScreenshotNotification>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for SendScreenshotNotificationQuery for " << random_id_ << ": " << to_string(ptr);
+    td->messages_manager_->check_send_message_result(random_id_, dialog_id_, ptr.get(),
+                                                     "SendScreenshotNotificationQuery");
+    td->updates_manager_->on_get_updates(std::move(ptr));
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for SendScreenshotNotificationQuery: " << status;
+    if (G()->close_flag() && G()->parameters().use_message_db) {
+      // do not send error, messages should be re-sent
+      return;
+    }
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "SendScreenshotNotificationQuery");
+    td->messages_manager_->on_send_message_fail(random_id_, status.clone());
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SetTypingQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+
+ public:
+  explicit SetTypingQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  NetQueryRef send(DialogId dialog_id, tl_object_ptr<telegram_api::SendMessageAction> &&action) {
+    dialog_id_ = dialog_id;
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Write);
+    CHECK(input_peer != nullptr);
+
+    auto net_query = G()->net_query_creator().create(
+        create_storer(telegram_api::messages_setTyping(std::move(input_peer), std::move(action))));
+    auto result = net_query.get_weak();
+    send_query(std::move(net_query));
+    return result;
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_setTyping>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    // ignore result
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.code() == NetQuery::Cancelled) {
+      return promise_.set_value(Unit());
+    }
+
+    LOG(INFO) << "Receive error for set typing: " << status;
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "SetTypingQuery");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class DeleteMessagesQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  int32 query_count_;
+
+ public:
+  explicit DeleteMessagesQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(vector<MessageId> &&message_ids, bool revoke) {
+    LOG(INFO) << "Send deleteMessagesQuery to delete " << format::as_array(message_ids);
+    int32 flags = 0;
+    if (revoke) {
+      flags |= telegram_api::messages_deleteMessages::REVOKE_MASK;
+    }
+
+    query_count_ = 0;
+    auto server_message_ids = MessagesManager::get_server_message_ids(message_ids);
+    const size_t MAX_SLICE_SIZE = 100;
+    for (size_t i = 0; i < server_message_ids.size(); i += MAX_SLICE_SIZE) {
+      auto end_i = i + MAX_SLICE_SIZE;
+      auto end = end_i < server_message_ids.size() ? server_message_ids.begin() + end_i : server_message_ids.end();
+      vector<int32> slice(server_message_ids.begin() + i, end);
+
+      query_count_++;
+      send_query(G()->net_query_creator().create(
+          create_storer(telegram_api::messages_deleteMessages(flags, false /*ignored*/, std::move(slice)))));
+    }
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_deleteMessages>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto affected_messages = result_ptr.move_as_ok();
+    CHECK(affected_messages->get_id() == telegram_api::messages_affectedMessages::ID);
+
+    if (affected_messages->pts_count_ > 0) {
+      td->messages_manager_->add_pending_update(make_tl_object<dummyUpdate>(), affected_messages->pts_,
+                                                affected_messages->pts_count_, false, "delete messages query");
+    }
+    if (--query_count_ == 0) {
+      promise_.set_value(Unit());
+    }
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for delete messages: " << status;
+    promise_.set_error(std::move(status));
+  }
+};
+
+class DeleteChannelMessagesQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  int32 query_count_;
+  ChannelId channel_id_;
+
+ public:
+  explicit DeleteChannelMessagesQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, vector<MessageId> &&message_ids) {
+    channel_id_ = channel_id;
+    LOG(INFO) << "Send deleteChannelMessagesQuery to delete " << format::as_array(message_ids) << " in the "
+              << channel_id;
+
+    query_count_ = 0;
+    auto server_message_ids = MessagesManager::get_server_message_ids(message_ids);
+    const size_t MAX_SLICE_SIZE = 100;
+    for (size_t i = 0; i < server_message_ids.size(); i += MAX_SLICE_SIZE) {
+      auto end_i = i + MAX_SLICE_SIZE;
+      auto end = end_i < server_message_ids.size() ? server_message_ids.begin() + end_i : server_message_ids.end();
+      vector<int32> slice(server_message_ids.begin() + i, end);
+
+      query_count_++;
+      auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+      CHECK(input_channel != nullptr);
+      send_query(G()->net_query_creator().create(
+          create_storer(telegram_api::channels_deleteMessages(std::move(input_channel), std::move(slice)))));
+    }
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_deleteMessages>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto affected_messages = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for deleteChannelMessages: " << to_string(affected_messages);
+    CHECK(affected_messages->get_id() == telegram_api::messages_affectedMessages::ID);
+
+    if (affected_messages->pts_count_ > 0) {
+      td->messages_manager_->add_pending_channel_update(DialogId(channel_id_), make_tl_object<dummyUpdate>(),
+                                                        affected_messages->pts_, affected_messages->pts_count_,
+                                                        "DeleteChannelMessagesQuery");
+    }
+    if (--query_count_ == 0) {
+      promise_.set_value(Unit());
+    }
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (!td->contacts_manager_->on_get_channel_error(channel_id_, status, "DeleteChannelMessagesQuery")) {
+      LOG(ERROR) << "Receive error for delete channel messages: " << status;
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetNotifySettingsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  NotificationSettingsScope scope_;
+
+ public:
+  explicit GetNotifySettingsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(NotificationSettingsScope scope) {
+    scope_ = scope;
+    auto input_notify_peer = td->messages_manager_->get_input_notify_peer(scope);
+    CHECK(input_notify_peer != nullptr);
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::account_getNotifySettings(std::move(input_notify_peer)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::account_getNotifySettings>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    td->messages_manager_->on_update_notify_settings(scope_, std::move(ptr));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class UpdateNotifySettingsQuery : public Td::ResultHandler {
+  NotificationSettingsScope scope_;
+
+ public:
+  void send(NotificationSettingsScope scope, const NotificationSettings &new_settings) {
+    auto input_notify_peer = td->messages_manager_->get_input_notify_peer(scope);
+    if (input_notify_peer == nullptr) {
+      return;
+    }
+    int32 flags = 0;
+    if (new_settings.show_preview) {
+      flags |= telegram_api::inputPeerNotifySettings::SHOW_PREVIEWS_MASK;
+    }
+    if (new_settings.silent_send_message) {
+      flags |= telegram_api::inputPeerNotifySettings::SILENT_MASK;
+    }
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::account_updateNotifySettings(
+        std::move(input_notify_peer),
+        make_tl_object<telegram_api::inputPeerNotifySettings>(flags, false /*ignored*/, false /*ignored*/,
+                                                              new_settings.mute_until, new_settings.sound)))));
+    scope_ = scope;
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::account_updateNotifySettings>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    if (!result) {
+      return on_error(id, Status::Error(400, "Receive false as result"));
+    }
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for set notification settings: " << status;
+    status.ignore();
+
+    if (!td->auth_manager_->is_bot() && td->messages_manager_->get_input_notify_peer(scope_) != nullptr) {
+      // trying to repair notification settings for this scope
+      td->create_handler<GetNotifySettingsQuery>(Promise<>())->send(scope_);
+    }
+  }
+};
+
+class ResetNotifySettingsQuery : public Td::ResultHandler {
+ public:
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::account_resetNotifySettings())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::account_resetNotifySettings>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    if (!result) {
+      return on_error(id, Status::Error(400, "Receive false as result"));
+    }
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(WARNING) << "Receive error for reset notification settings: " << status;
+    status.ignore();
+  }
+};
+
+class GetPeerSettingsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+
+ public:
+  explicit GetPeerSettingsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id) {
+    dialog_id_ = dialog_id;
+
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Read);
+    CHECK(input_peer != nullptr);
+
+    send_query(
+        G()->net_query_creator().create(create_storer(telegram_api::messages_getPeerSettings(std::move(input_peer)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getPeerSettings>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->messages_manager_->on_get_peer_settings(dialog_id_, result_ptr.move_as_ok());
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for get peer settings: " << status;
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "GetPeerSettingsQuery");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class UpdatePeerSettingsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+
+ public:
+  explicit UpdatePeerSettingsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id, bool is_spam_dialog) {
+    dialog_id_ = dialog_id;
+
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Read);
+    CHECK(input_peer != nullptr);
+
+    if (is_spam_dialog) {
+      send_query(
+          G()->net_query_creator().create(create_storer(telegram_api::messages_reportSpam(std::move(input_peer)))));
+    } else {
+      send_query(
+          G()->net_query_creator().create(create_storer(telegram_api::messages_hideReportSpam(std::move(input_peer)))));
+    }
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    static_assert(std::is_same<telegram_api::messages_reportSpam::ReturnType,
+                               telegram_api::messages_hideReportSpam::ReturnType>::value,
+                  "");
+    auto result_ptr = fetch_result<telegram_api::messages_reportSpam>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->messages_manager_->on_get_peer_settings(dialog_id_,
+                                                make_tl_object<telegram_api::peerSettings>(0, false /*ignored*/));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for update peer settings: " << status;
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "UpdatePeerSettingsQuery");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ReportEncryptedSpamQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+
+ public:
+  explicit ReportEncryptedSpamQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id) {
+    dialog_id_ = dialog_id;
+
+    auto input_peer = td->messages_manager_->get_input_encrypted_chat(dialog_id, AccessRights::Read);
+    CHECK(input_peer != nullptr);
+    LOG(INFO) << "Report spam in " << to_string(input_peer);
+
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_reportEncryptedSpam(std::move(input_peer)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_reportEncryptedSpam>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->messages_manager_->on_get_peer_settings(dialog_id_,
+                                                make_tl_object<telegram_api::peerSettings>(0, false /*ignored*/));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for report encrypted spam: " << status;
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "ReportEncryptedSpamQuery");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ReportPeerQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  DialogId dialog_id_;
+
+ public:
+  explicit ReportPeerQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(DialogId dialog_id, tl_object_ptr<telegram_api::ReportReason> &&report_reason,
+            const vector<MessageId> &message_ids) {
+    dialog_id_ = dialog_id;
+
+    auto input_peer = td->messages_manager_->get_input_peer(dialog_id, AccessRights::Read);
+    CHECK(input_peer != nullptr);
+
+    if (message_ids.empty()) {
+      send_query(G()->net_query_creator().create(
+          create_storer(telegram_api::account_reportPeer(std::move(input_peer), std::move(report_reason)))));
+    } else {
+      send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_report(
+          std::move(input_peer), MessagesManager::get_server_message_ids(message_ids), std::move(report_reason)))));
+    }
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    static_assert(
+        std::is_same<telegram_api::account_reportPeer::ReturnType, telegram_api::messages_report::ReturnType>::value,
+        "");
+    auto result_ptr = fetch_result<telegram_api::account_reportPeer>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    if (!result) {
+      return on_error(id, Status::Error(400, "Receive false as result"));
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for report peer: " << status;
+    td->messages_manager_->on_get_dialog_error(dialog_id_, status, "ReportPeerQuery");
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetChannelDifferenceQuery : public Td::ResultHandler {
+  DialogId dialog_id_;
+  int32 pts_;
+  int32 limit_;
+
+ public:
+  void send(DialogId dialog_id, tl_object_ptr<telegram_api::InputChannel> &&input_channel, int32 pts, int32 limit,
+            bool force) {
+    CHECK(pts >= 0);
+    dialog_id_ = dialog_id;
+    pts_ = pts;
+    limit_ = limit;
+    CHECK(input_channel != nullptr);
+
+    int32 flags = 0;
+    if (force) {
+      flags |= telegram_api::updates_getChannelDifference::FORCE_MASK;
+    }
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::updates_getChannelDifference(
+        flags, false /*ignored*/, std::move(input_channel), make_tl_object<telegram_api::channelMessagesFilterEmpty>(),
+        pts, limit))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::updates_getChannelDifference>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->messages_manager_->on_get_channel_difference(dialog_id_, pts_, limit_, result_ptr.move_as_ok());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (!td->messages_manager_->on_get_dialog_error(dialog_id_, status, "GetChannelDifferenceQuery")) {
+      LOG(ERROR) << "updates.getChannelDifference error for " << dialog_id_ << ": " << status;
+    }
+    td->messages_manager_->on_get_channel_difference(dialog_id_, pts_, limit_, nullptr);
+    status.ignore();
+  }
+};
+
+class ResolveUsernameQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  string username_;
+
+ public:
+  explicit ResolveUsernameQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(const string &username) {
+    username_ = username;
+
+    LOG(INFO) << "Send ResolveUsernameQuery with username = " << username;
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::contacts_resolveUsername(username))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::contacts_resolveUsername>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(DEBUG) << "Receive result for resolveUsername " << to_string(ptr);
+    td->contacts_manager_->on_get_users(std::move(ptr->users_));
+    td->contacts_manager_->on_get_chats(std::move(ptr->chats_));
+
+    td->messages_manager_->on_resolved_username(username_, DialogId(ptr->peer_));
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.message() == Slice("USERNAME_NOT_OCCUPIED")) {
+      td->messages_manager_->drop_username(username_);
+    }
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetChannelAdminLogQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  ChannelId channel_id_;
+  int64 random_id_;
+
+ public:
+  explicit GetChannelAdminLogQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ChannelId channel_id, const string &query, int64 from_event_id, int32 limit,
+            tl_object_ptr<telegram_api::channelAdminLogEventsFilter> filter,
+            vector<tl_object_ptr<telegram_api::InputUser>> input_users, int64 random_id) {
+    channel_id_ = channel_id;
+    random_id_ = random_id;
+
+    auto input_channel = td->contacts_manager_->get_input_channel(channel_id);
+    CHECK(input_channel != nullptr);
+
+    int32 flags = 0;
+    if (filter != nullptr) {
+      flags |= telegram_api::channels_getAdminLog::EVENTS_FILTER_MASK;
+    }
+    if (!input_users.empty()) {
+      flags |= telegram_api::channels_getAdminLog::ADMINS_MASK;
+    }
+
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::channels_getAdminLog(
+        flags, std::move(input_channel), query, std::move(filter), std::move(input_users), from_event_id, 0, limit))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::channels_getAdminLog>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->messages_manager_->on_get_event_log(random_id_, result_ptr.move_as_ok());
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->contacts_manager_->on_get_channel_error(channel_id_, status, "GetChannelAdminLogQuery");
+    td->messages_manager_->on_get_event_log(random_id_, nullptr);
+    promise_.set_error(std::move(status));
+  }
+};
+
+bool operator==(const InputMessageText &lhs, const InputMessageText &rhs) {
+  return lhs.text == rhs.text && lhs.disable_web_page_preview == rhs.disable_web_page_preview &&
+         lhs.clear_draft == rhs.clear_draft;
+}
+
+bool operator!=(const InputMessageText &lhs, const InputMessageText &rhs) {
+  return !(lhs == rhs);
+}
+
+class MessagesManager::UploadMediaCallback : public FileManager::UploadCallback {
+ public:
+  void on_progress(FileId file_id) override {
+  }
+  void on_upload_ok(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) override {
+    send_closure_later(G()->messages_manager(), &MessagesManager::on_upload_media, file_id, std::move(input_file),
+                       nullptr);
+  }
+  void on_upload_encrypted_ok(FileId file_id, tl_object_ptr<telegram_api::InputEncryptedFile> input_file) override {
+    send_closure_later(G()->messages_manager(), &MessagesManager::on_upload_media, file_id, nullptr,
+                       std::move(input_file));
+  }
+  void on_upload_error(FileId file_id, Status error) override {
+    send_closure_later(G()->messages_manager(), &MessagesManager::on_upload_media_error, file_id, std::move(error));
+  }
+};
+
+class MessagesManager::UploadThumbnailCallback : public FileManager::UploadCallback {
+ public:
+  void on_upload_ok(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) override {
+    send_closure_later(G()->messages_manager(), &MessagesManager::on_upload_thumbnail, file_id, std::move(input_file));
+  }
+  void on_upload_encrypted_ok(FileId file_id, tl_object_ptr<telegram_api::InputEncryptedFile> input_file) override {
+    UNREACHABLE();
+  }
+  void on_upload_error(FileId file_id, Status error) override {
+    send_closure_later(G()->messages_manager(), &MessagesManager::on_upload_thumbnail, file_id, nullptr);
+  }
+};
+
+class MessagesManager::UploadDialogPhotoCallback : public FileManager::UploadCallback {
+ public:
+  void on_upload_ok(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) override {
+    send_closure_later(G()->messages_manager(), &MessagesManager::on_upload_dialog_photo, file_id,
+                       std::move(input_file));
+  }
+  void on_upload_encrypted_ok(FileId file_id, tl_object_ptr<telegram_api::InputEncryptedFile> input_file) override {
+    UNREACHABLE();
+  }
+  void on_upload_error(FileId file_id, Status error) override {
+    send_closure_later(G()->messages_manager(), &MessagesManager::on_upload_dialog_photo_error, file_id,
+                       std::move(error));
+  }
+};
+
+template <class StorerT>
+static void store(const MessageContent *content, StorerT &storer) {
+  CHECK(content != nullptr);
+
+  Td *td = storer.context()->td().get_actor_unsafe();
+  CHECK(td != nullptr);
+
+  auto content_id = content->get_id();
+  store(content_id, storer);
+
+  switch (content_id) {
+    case MessageAnimation::ID: {
+      auto m = static_cast<const MessageAnimation *>(content);
+      td->animations_manager_->store_animation(m->file_id, storer);
+      store(m->caption, storer);
+      break;
+    }
+    case MessageAudio::ID: {
+      auto m = static_cast<const MessageAudio *>(content);
+      td->audios_manager_->store_audio(m->file_id, storer);
+      store(m->caption, storer);
+      store(true, storer);
+      break;
+    }
+    case MessageContact::ID: {
+      auto m = static_cast<const MessageContact *>(content);
+      store(m->contact, storer);
+      break;
+    }
+    case MessageDocument::ID: {
+      auto m = static_cast<const MessageDocument *>(content);
+      td->documents_manager_->store_document(m->file_id, storer);
+      store(m->caption, storer);
+      break;
+    }
+    case MessageGame::ID: {
+      auto m = static_cast<const MessageGame *>(content);
+      store(m->game, storer);
+      break;
+    }
+    case MessageInvoice::ID: {
+      auto m = static_cast<const MessageInvoice *>(content);
+      store(m->title, storer);
+      store(m->description, storer);
+      store(m->photo, storer);
+      store(m->start_parameter, storer);
+      store(m->invoice, storer);
+      store(m->payload, storer);
+      store(m->provider_token, storer);
+      store(m->provider_data, storer);
+      store(m->total_amount, storer);
+      store(m->receipt_message_id, storer);
+      break;
+    }
+    case MessageLiveLocation::ID: {
+      auto m = static_cast<const MessageLiveLocation *>(content);
+      store(m->location, storer);
+      store(m->period, storer);
+      break;
+    }
+    case MessageLocation::ID: {
+      auto m = static_cast<const MessageLocation *>(content);
+      store(m->location, storer);
+      break;
+    }
+    case MessagePhoto::ID: {
+      auto m = static_cast<const MessagePhoto *>(content);
+      store(m->photo, storer);
+      store(m->caption, storer);
+      break;
+    }
+    case MessageSticker::ID: {
+      auto m = static_cast<const MessageSticker *>(content);
+      td->stickers_manager_->store_sticker(m->file_id, false, storer);
+      break;
+    }
+    case MessageText::ID: {
+      auto m = static_cast<const MessageText *>(content);
+      store(m->text, storer);
+      store(m->web_page_id, storer);
+      break;
+    }
+    case MessageUnsupported::ID:
+      break;
+    case MessageVenue::ID: {
+      auto m = static_cast<const MessageVenue *>(content);
+      store(m->venue, storer);
+      break;
+    }
+    case MessageVideo::ID: {
+      auto m = static_cast<const MessageVideo *>(content);
+      td->videos_manager_->store_video(m->file_id, storer);
+      store(m->caption, storer);
+      break;
+    }
+    case MessageVideoNote::ID: {
+      auto m = static_cast<const MessageVideoNote *>(content);
+      td->video_notes_manager_->store_video_note(m->file_id, storer);
+      store(m->is_viewed, storer);
+      break;
+    }
+    case MessageVoiceNote::ID: {
+      auto m = static_cast<const MessageVoiceNote *>(content);
+      td->voice_notes_manager_->store_voice_note(m->file_id, storer);
+      store(m->caption, storer);
+      store(m->is_listened, storer);
+      break;
+    }
+    case MessageChatCreate::ID: {
+      auto m = static_cast<const MessageChatCreate *>(content);
+      store(m->title, storer);
+      store(m->participant_user_ids, storer);
+      break;
+    }
+    case MessageChatChangeTitle::ID: {
+      auto m = static_cast<const MessageChatChangeTitle *>(content);
+      store(m->title, storer);
+      break;
+    }
+    case MessageChatChangePhoto::ID: {
+      auto m = static_cast<const MessageChatChangePhoto *>(content);
+      store(m->photo, storer);
+      break;
+    }
+    case MessageChatDeletePhoto::ID:
+    case MessageChatDeleteHistory::ID:
+      break;
+    case MessageChatAddUsers::ID: {
+      auto m = static_cast<const MessageChatAddUsers *>(content);
+      store(m->user_ids, storer);
+      break;
+    }
+    case MessageChatJoinedByLink::ID:
+      break;
+    case MessageChatDeleteUser::ID: {
+      auto m = static_cast<const MessageChatDeleteUser *>(content);
+      store(m->user_id, storer);
+      break;
+    }
+    case MessageChatMigrateTo::ID: {
+      auto m = static_cast<const MessageChatMigrateTo *>(content);
+      store(m->migrated_to_channel_id, storer);
+      break;
+    }
+    case MessageChannelCreate::ID: {
+      auto m = static_cast<const MessageChannelCreate *>(content);
+      store(m->title, storer);
+      break;
+    }
+    case MessageChannelMigrateFrom::ID: {
+      auto m = static_cast<const MessageChannelMigrateFrom *>(content);
+      store(m->title, storer);
+      store(m->migrated_from_chat_id, storer);
+      break;
+    }
+    case MessagePinMessage::ID: {
+      auto m = static_cast<const MessagePinMessage *>(content);
+      store(m->message_id, storer);
+      break;
+    }
+    case MessageGameScore::ID: {
+      auto m = static_cast<const MessageGameScore *>(content);
+      store(m->game_message_id, storer);
+      store(m->game_id, storer);
+      store(m->score, storer);
+      break;
+    }
+    case MessageScreenshotTaken::ID:
+      break;
+    case MessageChatSetTtl::ID: {
+      auto m = static_cast<const MessageChatSetTtl *>(content);
+      store(m->ttl, storer);
+      break;
+    }
+    case MessageCall::ID: {
+      auto m = static_cast<const MessageCall *>(content);
+      store(m->call_id, storer);
+      store(m->duration, storer);
+      store(m->discard_reason, storer);
+      break;
+    }
+    case MessagePaymentSuccessful::ID: {
+      auto m = static_cast<const MessagePaymentSuccessful *>(content);
+      bool has_payload = !m->invoice_payload.empty();
+      bool has_shipping_option_id = !m->shipping_option_id.empty();
+      bool has_order_info = m->order_info != nullptr;
+      bool has_telegram_payment_charge_id = !m->telegram_payment_charge_id.empty();
+      bool has_provider_payment_charge_id = !m->provider_payment_charge_id.empty();
+      bool has_invoice_message_id = m->invoice_message_id.is_valid();
+      BEGIN_STORE_FLAGS();
+      STORE_FLAG(has_payload);
+      STORE_FLAG(has_shipping_option_id);
+      STORE_FLAG(has_order_info);
+      STORE_FLAG(has_telegram_payment_charge_id);
+      STORE_FLAG(has_provider_payment_charge_id);
+      STORE_FLAG(has_invoice_message_id);
+      END_STORE_FLAGS();
+      store(m->currency, storer);
+      store(m->total_amount, storer);
+      if (has_payload) {
+        store(m->total_amount, storer);
+      }
+      if (has_shipping_option_id) {
+        store(m->invoice_payload, storer);
+      }
+      if (has_order_info) {
+        store(*m->order_info, storer);
+      }
+      if (has_telegram_payment_charge_id) {
+        store(m->telegram_payment_charge_id, storer);
+      }
+      if (has_provider_payment_charge_id) {
+        store(m->provider_payment_charge_id, storer);
+      }
+      if (has_invoice_message_id) {
+        store(m->invoice_message_id, storer);
+      }
+      break;
+    }
+    case MessageContactRegistered::ID:
+      break;
+    case MessageExpiredPhoto::ID:
+      break;
+    case MessageExpiredVideo::ID:
+      break;
+    case MessageCustomServiceAction::ID: {
+      auto m = static_cast<const MessageCustomServiceAction *>(content);
+      store(m->message, storer);
+      break;
+    }
+    case MessageWebsiteConnected::ID: {
+      auto m = static_cast<const MessageWebsiteConnected *>(content);
+      store(m->domain_name, storer);
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+}
+
+template <class ParserT>
+static void parse_caption(FormattedText &caption, ParserT &parser) {
+  parse(caption.text, parser);
+  if (parser.version() >= static_cast<int32>(Version::AddCaptionEntities)) {
+    parse(caption.entities, parser);
+  } else {
+    caption.entities = find_entities(caption.text, false);
+  }
+}
+
+template <class ParserT>
+static void parse(unique_ptr<MessageContent> &content, ParserT &parser) {
+  Td *td = parser.context()->td().get_actor_unsafe();
+  CHECK(td != nullptr);
+
+  int32 content_id;
+  parse(content_id, parser);
+
+  bool is_bad = false;
+  switch (content_id) {
+    case MessageAnimation::ID: {
+      auto m = make_unique<MessageAnimation>();
+      m->file_id = td->animations_manager_->parse_animation(parser);
+      parse_caption(m->caption, parser);
+      is_bad = !m->file_id.is_valid();
+      content = std::move(m);
+      break;
+    }
+    case MessageAudio::ID: {
+      auto m = make_unique<MessageAudio>();
+      m->file_id = td->audios_manager_->parse_audio(parser);
+      parse_caption(m->caption, parser);
+      bool legacy_is_listened;
+      parse(legacy_is_listened, parser);
+      is_bad = !m->file_id.is_valid();
+      content = std::move(m);
+      break;
+    }
+    case MessageContact::ID: {
+      auto m = make_unique<MessageContact>();
+      parse(m->contact, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageDocument::ID: {
+      auto m = make_unique<MessageDocument>();
+      m->file_id = td->documents_manager_->parse_document(parser);
+      parse_caption(m->caption, parser);
+      is_bad = !m->file_id.is_valid();
+      content = std::move(m);
+      break;
+    }
+    case MessageGame::ID: {
+      auto m = make_unique<MessageGame>();
+      parse(m->game, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageInvoice::ID: {
+      auto m = make_unique<MessageInvoice>();
+      parse(m->title, parser);
+      parse(m->description, parser);
+      parse(m->photo, parser);
+      parse(m->start_parameter, parser);
+      parse(m->invoice, parser);
+      parse(m->payload, parser);
+      parse(m->provider_token, parser);
+      if (parser.version() >= static_cast<int32>(Version::AddMessageInvoiceProviderData)) {
+        parse(m->provider_data, parser);
+      } else {
+        m->provider_data.clear();
+      }
+      parse(m->total_amount, parser);
+      parse(m->receipt_message_id, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageLiveLocation::ID: {
+      auto m = make_unique<MessageLiveLocation>();
+      parse(m->location, parser);
+      parse(m->period, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageLocation::ID: {
+      auto m = make_unique<MessageLocation>();
+      parse(m->location, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessagePhoto::ID: {
+      auto m = make_unique<MessagePhoto>();
+      parse(m->photo, parser);
+      for (auto &photo_size : m->photo.photos) {
+        if (!photo_size.file_id.is_valid()) {
+          is_bad = true;
+        }
+      }
+      parse_caption(m->caption, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageSticker::ID: {
+      auto m = make_unique<MessageSticker>();
+      m->file_id = td->stickers_manager_->parse_sticker(false, parser);
+      is_bad = !m->file_id.is_valid();
+      content = std::move(m);
+      break;
+    }
+    case MessageText::ID: {
+      auto m = make_unique<MessageText>();
+      parse(m->text, parser);
+      parse(m->web_page_id, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageUnsupported::ID:
+      content = make_unique<MessageUnsupported>();
+      break;
+    case MessageVenue::ID: {
+      auto m = make_unique<MessageVenue>();
+      parse(m->venue, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageVideo::ID: {
+      auto m = make_unique<MessageVideo>();
+      m->file_id = td->videos_manager_->parse_video(parser);
+      parse_caption(m->caption, parser);
+      is_bad = !m->file_id.is_valid();
+      content = std::move(m);
+      break;
+    }
+    case MessageVideoNote::ID: {
+      auto m = make_unique<MessageVideoNote>();
+      m->file_id = td->video_notes_manager_->parse_video_note(parser);
+      parse(m->is_viewed, parser);
+      is_bad = !m->file_id.is_valid();
+      content = std::move(m);
+      break;
+    }
+    case MessageVoiceNote::ID: {
+      auto m = make_unique<MessageVoiceNote>();
+      m->file_id = td->voice_notes_manager_->parse_voice_note(parser);
+      parse_caption(m->caption, parser);
+      parse(m->is_listened, parser);
+      is_bad = !m->file_id.is_valid();
+      content = std::move(m);
+      break;
+    }
+    case MessageChatCreate::ID: {
+      auto m = make_unique<MessageChatCreate>();
+      parse(m->title, parser);
+      parse(m->participant_user_ids, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageChatChangeTitle::ID: {
+      auto m = make_unique<MessageChatChangeTitle>();
+      parse(m->title, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageChatChangePhoto::ID: {
+      auto m = make_unique<MessageChatChangePhoto>();
+      parse(m->photo, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageChatDeletePhoto::ID:
+      content = make_unique<MessageChatDeletePhoto>();
+      break;
+    case MessageChatDeleteHistory::ID:
+      content = make_unique<MessageChatDeleteHistory>();
+      break;
+    case MessageChatAddUsers::ID: {
+      auto m = make_unique<MessageChatAddUsers>();
+      parse(m->user_ids, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageChatJoinedByLink::ID:
+      content = make_unique<MessageChatJoinedByLink>();
+      break;
+    case MessageChatDeleteUser::ID: {
+      auto m = make_unique<MessageChatDeleteUser>();
+      parse(m->user_id, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageChatMigrateTo::ID: {
+      auto m = make_unique<MessageChatMigrateTo>();
+      parse(m->migrated_to_channel_id, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageChannelCreate::ID: {
+      auto m = make_unique<MessageChannelCreate>();
+      parse(m->title, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageChannelMigrateFrom::ID: {
+      auto m = make_unique<MessageChannelMigrateFrom>();
+      parse(m->title, parser);
+      parse(m->migrated_from_chat_id, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessagePinMessage::ID: {
+      auto m = make_unique<MessagePinMessage>();
+      parse(m->message_id, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageGameScore::ID: {
+      auto m = make_unique<MessageGameScore>();
+      parse(m->game_message_id, parser);
+      parse(m->game_id, parser);
+      parse(m->score, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageScreenshotTaken::ID:
+      content = make_unique<MessageScreenshotTaken>();
+      break;
+    case MessageChatSetTtl::ID: {
+      auto m = make_unique<MessageChatSetTtl>();
+      parse(m->ttl, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageCall::ID: {
+      auto m = make_unique<MessageCall>();
+      parse(m->call_id, parser);
+      parse(m->duration, parser);
+      parse(m->discard_reason, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessagePaymentSuccessful::ID: {
+      auto m = make_unique<MessagePaymentSuccessful>();
+      bool has_payload;
+      bool has_shipping_option_id;
+      bool has_order_info;
+      bool has_telegram_payment_charge_id;
+      bool has_provider_payment_charge_id;
+      bool has_invoice_message_id;
+      BEGIN_PARSE_FLAGS();
+      PARSE_FLAG(has_payload);
+      PARSE_FLAG(has_shipping_option_id);
+      PARSE_FLAG(has_order_info);
+      PARSE_FLAG(has_telegram_payment_charge_id);
+      PARSE_FLAG(has_provider_payment_charge_id);
+      PARSE_FLAG(has_invoice_message_id);
+      END_PARSE_FLAGS();
+      parse(m->currency, parser);
+      parse(m->total_amount, parser);
+      if (has_payload) {
+        parse(m->total_amount, parser);
+      }
+      if (has_shipping_option_id) {
+        parse(m->invoice_payload, parser);
+      }
+      if (has_order_info) {
+        m->order_info = make_unique<OrderInfo>();
+        parse(*m->order_info, parser);
+      }
+      if (has_telegram_payment_charge_id) {
+        parse(m->telegram_payment_charge_id, parser);
+      }
+      if (has_provider_payment_charge_id) {
+        parse(m->provider_payment_charge_id, parser);
+      }
+      if (has_invoice_message_id) {
+        parse(m->invoice_message_id, parser);
+      }
+      content = std::move(m);
+      break;
+    }
+    case MessageContactRegistered::ID:
+      content = make_unique<MessageContactRegistered>();
+      break;
+    case MessageExpiredPhoto::ID:
+      content = make_unique<MessageExpiredPhoto>();
+      break;
+    case MessageExpiredVideo::ID:
+      content = make_unique<MessageExpiredVideo>();
+      break;
+    case MessageCustomServiceAction::ID: {
+      auto m = make_unique<MessageCustomServiceAction>();
+      parse(m->message, parser);
+      content = std::move(m);
+      break;
+    }
+    case MessageWebsiteConnected::ID: {
+      auto m = make_unique<MessageWebsiteConnected>();
+      parse(m->domain_name, parser);
+      content = std::move(m);
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+  if (is_bad) {
+    LOG(ERROR) << "Load a message with an invalid content of type " << content_id;
+    content = make_unique<MessageUnsupported>();
+  }
+}
+
+template <class StorerT>
+void MessagesManager::Message::store(StorerT &storer) const {
+  using td::store;
+  bool has_sender = sender_user_id.is_valid();
+  bool has_edit_date = edit_date > 0;
+  bool has_random_id = random_id != 0;
+  bool is_forwarded = forward_info != nullptr;
+  bool is_reply = reply_to_message_id.is_valid();
+  bool is_reply_to_random_id = reply_to_random_id != 0;
+  bool is_via_bot = via_bot_user_id.is_valid();
+  bool has_views = views > 0;
+  bool has_reply_markup = reply_markup != nullptr;
+  bool has_ttl = ttl != 0;
+  bool has_author_signature = !author_signature.empty();
+  bool has_forward_author_signature = is_forwarded && !forward_info->author_signature.empty();
+  bool has_media_album_id = media_album_id != 0;
+  bool has_forward_from =
+      is_forwarded && (forward_info->from_dialog_id.is_valid() || forward_info->from_message_id.is_valid());
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(is_channel_post);
+  STORE_FLAG(is_outgoing);
+  STORE_FLAG(is_failed_to_send);
+  STORE_FLAG(disable_notification);
+  STORE_FLAG(contains_mention);
+  STORE_FLAG(from_background);
+  STORE_FLAG(disable_web_page_preview);
+  STORE_FLAG(clear_draft);
+  STORE_FLAG(have_previous);
+  STORE_FLAG(have_next);
+  STORE_FLAG(has_sender);
+  STORE_FLAG(has_edit_date);
+  STORE_FLAG(has_random_id);
+  STORE_FLAG(is_forwarded);
+  STORE_FLAG(is_reply);
+  STORE_FLAG(is_reply_to_random_id);
+  STORE_FLAG(is_via_bot);
+  STORE_FLAG(has_views);
+  STORE_FLAG(has_reply_markup);
+  STORE_FLAG(has_ttl);
+  STORE_FLAG(has_author_signature);
+  STORE_FLAG(has_forward_author_signature);
+  STORE_FLAG(had_reply_markup);
+  STORE_FLAG(contains_unread_mention);
+  STORE_FLAG(has_media_album_id);
+  STORE_FLAG(has_forward_from);
+  STORE_FLAG(in_game_share);
+  STORE_FLAG(is_content_secret);
+  END_STORE_FLAGS();
+
+  store(message_id, storer);
+  if (has_sender) {
+    store(sender_user_id, storer);
+  }
+  store(date, storer);
+  if (has_edit_date) {
+    store(edit_date, storer);
+  }
+  if (has_random_id) {
+    store(random_id, storer);
+  }
+  if (is_forwarded) {
+    store(forward_info->sender_user_id, storer);
+    store(forward_info->date, storer);
+    store(forward_info->dialog_id, storer);
+    store(forward_info->message_id, storer);
+    if (has_forward_author_signature) {
+      store(forward_info->author_signature, storer);
+    }
+    if (has_forward_from) {
+      store(forward_info->from_dialog_id, storer);
+      store(forward_info->from_message_id, storer);
+    }
+  }
+  if (is_reply) {
+    store(reply_to_message_id, storer);
+  }
+  if (is_reply_to_random_id) {
+    store(reply_to_random_id, storer);
+  }
+  if (is_via_bot) {
+    store(via_bot_user_id, storer);
+  }
+  if (has_views) {
+    store(views, storer);
+  }
+  if (has_ttl) {
+    store(ttl, storer);
+    double server_time = storer.context()->server_time();
+    if (ttl_expires_at == 0) {
+      store(-1.0, storer);
+    } else {
+      double ttl_left = max(ttl_expires_at - Time::now_cached(), 0.0);
+      store(ttl_left, storer);
+      store(server_time, storer);
+    }
+  }
+  if (has_author_signature) {
+    store(author_signature, storer);
+  }
+  if (has_media_album_id) {
+    store(media_album_id, storer);
+  }
+  store(static_cast<const MessageContent *>(content.get()), storer);  // TODO unique_ptr with const propagation
+  if (has_reply_markup) {
+    store(*reply_markup, storer);
+  }
+}
+
+// do not forget to resolve message dependencies
+template <class ParserT>
+void MessagesManager::Message::parse(ParserT &parser) {
+  using td::parse;
+  bool has_sender;
+  bool has_edit_date;
+  bool has_random_id;
+  bool is_forwarded;
+  bool is_reply;
+  bool is_reply_to_random_id;
+  bool is_via_bot;
+  bool has_views;
+  bool has_reply_markup;
+  bool has_ttl;
+  bool has_author_signature;
+  bool has_forward_author_signature;
+  bool has_media_album_id;
+  bool has_forward_from;
+  BEGIN_PARSE_FLAGS();
+  PARSE_FLAG(is_channel_post);
+  PARSE_FLAG(is_outgoing);
+  PARSE_FLAG(is_failed_to_send);
+  PARSE_FLAG(disable_notification);
+  PARSE_FLAG(contains_mention);
+  PARSE_FLAG(from_background);
+  PARSE_FLAG(disable_web_page_preview);
+  PARSE_FLAG(clear_draft);
+  PARSE_FLAG(have_previous);
+  PARSE_FLAG(have_next);
+  PARSE_FLAG(has_sender);
+  PARSE_FLAG(has_edit_date);
+  PARSE_FLAG(has_random_id);
+  PARSE_FLAG(is_forwarded);
+  PARSE_FLAG(is_reply);
+  PARSE_FLAG(is_reply_to_random_id);
+  PARSE_FLAG(is_via_bot);
+  PARSE_FLAG(has_views);
+  PARSE_FLAG(has_reply_markup);
+  PARSE_FLAG(has_ttl);
+  PARSE_FLAG(has_author_signature);
+  PARSE_FLAG(has_forward_author_signature);
+  PARSE_FLAG(had_reply_markup);
+  PARSE_FLAG(contains_unread_mention);
+  PARSE_FLAG(has_media_album_id);
+  PARSE_FLAG(has_forward_from);
+  PARSE_FLAG(in_game_share);
+  PARSE_FLAG(is_content_secret);
+  END_PARSE_FLAGS();
+
+  parse(message_id, parser);
+  random_y = get_random_y(message_id);
+  if (has_sender) {
+    parse(sender_user_id, parser);
+  }
+  parse(date, parser);
+  if (has_edit_date) {
+    parse(edit_date, parser);
+  }
+  if (has_random_id) {
+    parse(random_id, parser);
+  }
+  if (is_forwarded) {
+    forward_info = make_unique<MessageForwardInfo>();
+    parse(forward_info->sender_user_id, parser);
+    parse(forward_info->date, parser);
+    parse(forward_info->dialog_id, parser);
+    parse(forward_info->message_id, parser);
+    if (has_forward_author_signature) {
+      parse(forward_info->author_signature, parser);
+    }
+    if (has_forward_from) {
+      parse(forward_info->from_dialog_id, parser);
+      parse(forward_info->from_message_id, parser);
+    }
+  }
+  if (is_reply) {
+    parse(reply_to_message_id, parser);
+  }
+  if (is_reply_to_random_id) {
+    parse(reply_to_random_id, parser);
+  }
+  if (is_via_bot) {
+    parse(via_bot_user_id, parser);
+  }
+  if (has_views) {
+    parse(views, parser);
+  }
+  if (has_ttl) {
+    parse(ttl, parser);
+    double ttl_left;
+    parse(ttl_left, parser);
+    if (ttl_left < -0.1) {
+      ttl_expires_at = 0;
+    } else {
+      double old_server_time;
+      parse(old_server_time, parser);
+      double passed_server_time = max(parser.context()->server_time() - old_server_time, 0.0);
+      ttl_left = max(ttl_left - passed_server_time, 0.0);
+      ttl_expires_at = Time::now_cached() + ttl_left;
+    }
+  }
+  if (has_author_signature) {
+    parse(author_signature, parser);
+  }
+  if (has_media_album_id) {
+    parse(media_album_id, parser);
+  }
+  parse(content, parser);
+  if (has_reply_markup) {
+    reply_markup = make_unique<ReplyMarkup>();
+    parse(*reply_markup, parser);
+  }
+  is_content_secret |= is_secret_message_content(ttl, content->get_id());  // repair is_content_secret for old messages
+}
+
+template <class StorerT>
+void store(const NotificationSettings &notification_settings, StorerT &storer) {
+  bool is_muted = notification_settings.mute_until != 0 && notification_settings.mute_until > G()->unix_time();
+  bool has_sound = notification_settings.sound != "default";
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(is_muted);
+  STORE_FLAG(has_sound);
+  STORE_FLAG(notification_settings.show_preview);
+  STORE_FLAG(notification_settings.silent_send_message);
+  STORE_FLAG(notification_settings.is_synchronized);
+  END_STORE_FLAGS();
+  if (is_muted) {
+    store(notification_settings.mute_until, storer);
+  }
+  if (has_sound) {
+    store(notification_settings.sound, storer);
+  }
+}
+
+template <class ParserT>
+void parse(NotificationSettings &notification_settings, ParserT &parser) {
+  bool is_muted;
+  bool has_sound;
+  BEGIN_PARSE_FLAGS();
+  PARSE_FLAG(is_muted);
+  PARSE_FLAG(has_sound);
+  PARSE_FLAG(notification_settings.show_preview);
+  PARSE_FLAG(notification_settings.silent_send_message);
+  PARSE_FLAG(notification_settings.is_synchronized);
+  END_PARSE_FLAGS();
+  if (is_muted) {
+    parse(notification_settings.mute_until, parser);
+  }
+  if (has_sound) {
+    parse(notification_settings.sound, parser);
+  }
+}
+
+template <class StorerT>
+void store(const InputMessageText &input_message_text, StorerT &storer) {
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(input_message_text.disable_web_page_preview);
+  STORE_FLAG(input_message_text.clear_draft);
+  END_STORE_FLAGS();
+  store(input_message_text.text, storer);
+}
+
+template <class ParserT>
+void parse(InputMessageText &input_message_text, ParserT &parser) {
+  BEGIN_PARSE_FLAGS();
+  PARSE_FLAG(input_message_text.disable_web_page_preview);
+  PARSE_FLAG(input_message_text.clear_draft);
+  END_PARSE_FLAGS();
+  parse(input_message_text.text, parser);
+}
+
+template <class StorerT>
+void store(const DraftMessage &draft_message, StorerT &storer) {
+  store(draft_message.date, storer);
+  store(draft_message.reply_to_message_id, storer);
+  store(draft_message.input_message_text, storer);
+}
+
+template <class ParserT>
+void parse(DraftMessage &draft_message, ParserT &parser) {
+  parse(draft_message.date, parser);
+  parse(draft_message.reply_to_message_id, parser);
+  parse(draft_message.input_message_text, parser);
+}
+
+template <class StorerT>
+void MessagesManager::Dialog::store(StorerT &storer) const {
+  using td::store;
+  const Message *last_database_message = nullptr;
+  if (last_database_message_id.is_valid()) {
+    last_database_message = get_message(this, last_database_message_id);
+  }
+
+  bool has_draft_message = draft_message != nullptr;
+  bool has_last_database_message = last_database_message != nullptr;
+  bool has_first_database_message_id = first_database_message_id.is_valid();
+  bool is_pinned = pinned_order != DEFAULT_ORDER;
+  bool has_first_database_message_id_by_index = true;
+  bool has_message_count_by_index = true;
+  bool has_client_data = !client_data.empty();
+  bool has_last_read_all_mentions_message_id = last_read_all_mentions_message_id.is_valid();
+  bool has_max_unavailable_message_id = max_unavailable_message_id.is_valid();
+  bool has_local_unread_count = local_unread_count != 0;
+  bool has_deleted_last_message = delete_last_message_date > 0;
+  bool has_last_clear_history_message_id = last_clear_history_message_id.is_valid();
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(has_draft_message);
+  STORE_FLAG(has_last_database_message);
+  STORE_FLAG(know_can_report_spam);
+  STORE_FLAG(can_report_spam);
+  STORE_FLAG(has_first_database_message_id);
+  STORE_FLAG(is_pinned);
+  STORE_FLAG(has_first_database_message_id_by_index);
+  STORE_FLAG(has_message_count_by_index);
+  STORE_FLAG(has_client_data);
+  STORE_FLAG(need_restore_reply_markup);
+  STORE_FLAG(have_full_history);
+  STORE_FLAG(has_last_read_all_mentions_message_id);
+  STORE_FLAG(has_max_unavailable_message_id);
+  STORE_FLAG(is_last_read_inbox_message_id_inited);
+  STORE_FLAG(is_last_read_outbox_message_id_inited);
+  STORE_FLAG(has_local_unread_count);
+  STORE_FLAG(has_deleted_last_message);
+  STORE_FLAG(has_last_clear_history_message_id);
+  STORE_FLAG(is_last_message_deleted_locally);
+  STORE_FLAG(has_contact_registered_message);
+  END_STORE_FLAGS();
+
+  store(dialog_id, storer);  // must be stored at offset 4
+  store(last_new_message_id, storer);
+  store(server_unread_count, storer);
+  if (has_local_unread_count) {
+    store(local_unread_count, storer);
+  }
+  store(last_read_inbox_message_id, storer);
+  store(last_read_outbox_message_id, storer);
+  store(reply_markup_message_id, storer);
+  store(notification_settings, storer);
+  if (has_draft_message) {
+    store(*draft_message, storer);
+  }
+  store(last_clear_history_date, storer);
+  store(order, storer);
+  if (has_last_database_message) {
+    store(*last_database_message, storer);
+  }
+  if (has_first_database_message_id) {
+    store(first_database_message_id, storer);
+  }
+  if (is_pinned) {
+    store(pinned_order, storer);
+  }
+  if (has_deleted_last_message) {
+    store(delete_last_message_date, storer);
+    store(deleted_last_message_id, storer);
+  }
+  if (has_last_clear_history_message_id) {
+    store(last_clear_history_message_id, storer);
+  }
+
+  if (has_first_database_message_id_by_index) {
+    store(static_cast<int32>(first_database_message_id_by_index.size()), storer);
+    for (auto first_message_id : first_database_message_id_by_index) {
+      store(first_message_id, storer);
+    }
+  }
+  if (has_message_count_by_index) {
+    store(static_cast<int32>(message_count_by_index.size()), storer);
+    for (auto message_count : message_count_by_index) {
+      store(message_count, storer);
+    }
+  }
+  if (has_client_data) {
+    store(client_data, storer);
+  }
+  if (has_last_read_all_mentions_message_id) {
+    store(last_read_all_mentions_message_id, storer);
+  }
+  if (has_max_unavailable_message_id) {
+    store(max_unavailable_message_id, storer);
+  }
+}
+
+// do not forget to resolve dialog dependencies including dependencies of last_message
+template <class ParserT>
+void MessagesManager::Dialog::parse(ParserT &parser) {
+  using td::parse;
+  bool has_draft_message;
+  bool has_last_database_message;
+  bool has_first_database_message_id;
+  bool is_pinned;
+  bool has_first_database_message_id_by_index;
+  bool has_message_count_by_index;
+  bool has_client_data;
+  bool has_last_read_all_mentions_message_id;
+  bool has_max_unavailable_message_id;
+  bool has_local_unread_count;
+  bool has_deleted_last_message;
+  bool has_last_clear_history_message_id;
+  BEGIN_PARSE_FLAGS();
+  PARSE_FLAG(has_draft_message);
+  PARSE_FLAG(has_last_database_message);
+  PARSE_FLAG(know_can_report_spam);
+  PARSE_FLAG(can_report_spam);
+  PARSE_FLAG(has_first_database_message_id);
+  PARSE_FLAG(is_pinned);
+  PARSE_FLAG(has_first_database_message_id_by_index);
+  PARSE_FLAG(has_message_count_by_index);
+  PARSE_FLAG(has_client_data);
+  PARSE_FLAG(need_restore_reply_markup);
+  PARSE_FLAG(have_full_history);
+  PARSE_FLAG(has_last_read_all_mentions_message_id);
+  PARSE_FLAG(has_max_unavailable_message_id);
+  PARSE_FLAG(is_last_read_inbox_message_id_inited);
+  PARSE_FLAG(is_last_read_outbox_message_id_inited);
+  PARSE_FLAG(has_local_unread_count);
+  PARSE_FLAG(has_deleted_last_message);
+  PARSE_FLAG(has_last_clear_history_message_id);
+  PARSE_FLAG(is_last_message_deleted_locally);
+  PARSE_FLAG(has_contact_registered_message);
+  END_PARSE_FLAGS();
+
+  parse(dialog_id, parser);  // must be stored at offset 4
+  parse(last_new_message_id, parser);
+  parse(server_unread_count, parser);
+  if (has_local_unread_count) {
+    parse(local_unread_count, parser);
+  }
+  parse(last_read_inbox_message_id, parser);
+  if (last_read_inbox_message_id.is_valid()) {
+    is_last_read_inbox_message_id_inited = true;
+  }
+  parse(last_read_outbox_message_id, parser);
+  if (last_read_outbox_message_id.is_valid()) {
+    is_last_read_outbox_message_id_inited = true;
+  }
+  parse(reply_markup_message_id, parser);
+  parse(notification_settings, parser);
+  if (has_draft_message) {
+    draft_message = make_unique<DraftMessage>();
+    parse(*draft_message, parser);
+  }
+  parse(last_clear_history_date, parser);
+  parse(order, parser);
+  if (has_last_database_message) {
+    messages = make_unique<Message>();
+    parse(*messages, parser);
+  }
+  if (has_first_database_message_id) {
+    parse(first_database_message_id, parser);
+  }
+  if (is_pinned) {
+    parse(pinned_order, parser);
+  }
+  if (has_deleted_last_message) {
+    parse(delete_last_message_date, parser);
+    parse(deleted_last_message_id, parser);
+  }
+  if (has_last_clear_history_message_id) {
+    parse(last_clear_history_message_id, parser);
+  }
+
+  if (has_first_database_message_id_by_index) {
+    int32 size;
+    parse(size, parser);
+    CHECK(static_cast<size_t>(size) <= first_database_message_id_by_index.size())
+        << size << " " << first_database_message_id_by_index.size();
+    for (int32 i = 0; i < size; i++) {
+      parse(first_database_message_id_by_index[i], parser);
+    }
+  }
+  if (has_message_count_by_index) {
+    int32 size;
+    parse(size, parser);
+    CHECK(static_cast<size_t>(size) <= message_count_by_index.size());
+    for (int32 i = 0; i < size; i++) {
+      parse(message_count_by_index[i], parser);
+    }
+  }
+  unread_mention_count = message_count_by_index[search_messages_filter_index(SearchMessagesFilter::UnreadMention)];
+  LOG(INFO) << "Set unread mention message count in " << dialog_id << " to " << unread_mention_count;
+  if (unread_mention_count < 0) {
+    unread_mention_count = 0;
+  }
+  if (has_client_data) {
+    parse(client_data, parser);
+  }
+  if (has_last_read_all_mentions_message_id) {
+    parse(last_read_all_mentions_message_id, parser);
+  }
+  if (has_max_unavailable_message_id) {
+    parse(max_unavailable_message_id, parser);
+  }
+}
+
+template <class StorerT>
+void store(const CallsDbState &state, StorerT &storer) {
+  store(static_cast<int32>(state.first_calls_database_message_id_by_index.size()), storer);
+  for (auto first_message_id : state.first_calls_database_message_id_by_index) {
+    store(first_message_id, storer);
+  }
+  store(static_cast<int32>(state.message_count_by_index.size()), storer);
+  for (auto message_count : state.message_count_by_index) {
+    store(message_count, storer);
+  }
+}
+
+template <class ParserT>
+void parse(CallsDbState &state, ParserT &parser) {
+  int32 size;
+  parse(size, parser);
+  CHECK(static_cast<size_t>(size) <= state.first_calls_database_message_id_by_index.size())
+      << size << " " << state.first_calls_database_message_id_by_index.size();
+  for (int32 i = 0; i < size; i++) {
+    parse(state.first_calls_database_message_id_by_index[i], parser);
+  }
+  parse(size, parser);
+  CHECK(static_cast<size_t>(size) <= state.message_count_by_index.size());
+  for (int32 i = 0; i < size; i++) {
+    parse(state.message_count_by_index[i], parser);
+  }
+}
+
+void MessagesManager::load_calls_db_state() {
+  if (!G()->parameters().use_message_db) {
+    return;
+  }
+  std::fill(calls_db_state_.message_count_by_index.begin(), calls_db_state_.message_count_by_index.end(), -1);
+  auto value = G()->td_db()->get_sqlite_sync_pmc()->get("calls_db_state");
+  if (value.empty()) {
+    return;
+  }
+  log_event_parse(calls_db_state_, value).ensure();
+  LOG(INFO) << "Save calls database state " << calls_db_state_.first_calls_database_message_id_by_index[0] << " ("
+            << calls_db_state_.message_count_by_index[0] << ") "
+            << calls_db_state_.first_calls_database_message_id_by_index[1] << " ("
+            << calls_db_state_.message_count_by_index[1] << ")";
+}
+
+void MessagesManager::save_calls_db_state() {
+  if (!G()->parameters().use_message_db) {
+    return;
+  }
+
+  LOG(INFO) << "Save calls database state " << calls_db_state_.first_calls_database_message_id_by_index[0] << " ("
+            << calls_db_state_.message_count_by_index[0] << ") "
+            << calls_db_state_.first_calls_database_message_id_by_index[1] << " ("
+            << calls_db_state_.message_count_by_index[1] << ")";
+  G()->td_db()->get_sqlite_pmc()->set("calls_db_state", log_event_store(calls_db_state_).as_slice().str(), Auto());
+}
+
+MessagesManager::Dialog::~Dialog() {
+  if (!G()->close_flag()) {
+    LOG(ERROR) << "Destroy " << dialog_id;
+  }
+}
+
+MessagesManager::MessagesManager(Td *td, ActorShared<> parent) : td_(td), parent_(std::move(parent)) {
+  //  td_->create_handler<GetDialogListQuery>()->send(2147000000, ServerMessageId(), DialogId(), 5);
+
+  upload_media_callback_ = std::make_shared<UploadMediaCallback>();
+  upload_thumbnail_callback_ = std::make_shared<UploadThumbnailCallback>();
+  upload_dialog_photo_callback_ = std::make_shared<UploadDialogPhotoCallback>();
+
+  channel_get_difference_timeout_.set_callback(on_channel_get_difference_timeout_callback);
+  channel_get_difference_timeout_.set_callback_data(static_cast<void *>(this));
+
+  channel_get_difference_retry_timeout_.set_callback(on_channel_get_difference_timeout_callback);
+  channel_get_difference_retry_timeout_.set_callback_data(static_cast<void *>(this));
+
+  pending_message_views_timeout_.set_callback(on_pending_message_views_timeout_callback);
+  pending_message_views_timeout_.set_callback_data(static_cast<void *>(this));
+
+  pending_draft_message_timeout_.set_callback(on_pending_draft_message_timeout_callback);
+  pending_draft_message_timeout_.set_callback_data(static_cast<void *>(this));
+
+  pending_updated_dialog_timeout_.set_callback(on_pending_updated_dialog_timeout_callback);
+  pending_updated_dialog_timeout_.set_callback_data(static_cast<void *>(this));
+
+  pending_unload_dialog_timeout_.set_callback(on_pending_unload_dialog_timeout_callback);
+  pending_unload_dialog_timeout_.set_callback_data(static_cast<void *>(this));
+
+  dialog_unmute_timeout_.set_callback(on_dialog_unmute_timeout_callback);
+  dialog_unmute_timeout_.set_callback_data(static_cast<void *>(this));
+
+  pending_send_dialog_action_timeout_.set_callback(on_pending_send_dialog_action_timeout_callback);
+  pending_send_dialog_action_timeout_.set_callback_data(static_cast<void *>(this));
+
+  active_dialog_action_timeout_.set_callback(on_active_dialog_action_timeout_callback);
+  active_dialog_action_timeout_.set_callback_data(static_cast<void *>(this));
+
+  sequence_dispatcher_ = create_actor<MultiSequenceDispatcher>("multi sequence dispatcher");
+
+  if (G()->parameters().use_message_db) {
+    auto last_database_server_dialog_date_string = G()->td_db()->get_binlog_pmc()->get("last_server_dialog_date");
+    if (!last_database_server_dialog_date_string.empty()) {
+      string order_str;
+      string dialog_id_str;
+      std::tie(order_str, dialog_id_str) = split(last_database_server_dialog_date_string);
+
+      auto r_order = to_integer_safe<int64>(order_str);
+      auto r_dialog_id = to_integer_safe<int64>(dialog_id_str);
+      if (r_order.is_error() || r_dialog_id.is_error()) {
+        LOG(ERROR) << "Can't parse " << last_database_server_dialog_date_string;
+      } else {
+        last_database_server_dialog_date_ = DialogDate(r_order.ok(), DialogId(r_dialog_id.ok()));
+      }
+    }
+    LOG(INFO) << "Load last_database_server_dialog_date_ = " << last_database_server_dialog_date_;
+
+    auto unread_message_count_string = G()->td_db()->get_binlog_pmc()->get("unread_message_count");
+    if (!unread_message_count_string.empty()) {
+      string total_count;
+      string muted_count;
+      std::tie(total_count, muted_count) = split(unread_message_count_string);
+
+      auto r_total_count = to_integer_safe<int32>(total_count);
+      auto r_muted_count = to_integer_safe<int32>(muted_count);
+      if (r_total_count.is_error() || r_muted_count.is_error()) {
+        LOG(ERROR) << "Can't parse " << unread_message_count_string;
+      } else {
+        unread_message_total_count_ = r_total_count.ok();
+        unread_message_muted_count_ = r_muted_count.ok();
+        is_unread_count_inited_ = true;
+        send_update_unread_message_count(DialogId(), true, "load unread_message_count");
+      }
+    }
+    LOG(INFO) << "Load last_database_server_dialog_date_ = " << last_database_server_dialog_date_;
+  } else {
+    G()->td_db()->get_binlog_pmc()->erase("last_server_dialog_date");
+    G()->td_db()->get_binlog_pmc()->erase("unread_message_count");
+  }
+}
+
+MessagesManager::~MessagesManager() = default;
+
+void MessagesManager::on_channel_get_difference_timeout_callback(void *messages_manager_ptr, int64 dialog_id_int) {
+  if (G()->close_flag()) {
+    return;
+  }
+
+  auto messages_manager = static_cast<MessagesManager *>(messages_manager_ptr);
+  DialogId dialog_id(dialog_id_int);
+  CHECK(dialog_id.get_type() == DialogType::Channel);
+  auto d = messages_manager->get_dialog(dialog_id);
+  CHECK(d != nullptr);
+  messages_manager->get_channel_difference(dialog_id, d->pts, true, "on_channel_get_difference_timeout_callback");
+}
+
+void MessagesManager::on_pending_message_views_timeout_callback(void *messages_manager_ptr, int64 dialog_id_int) {
+  if (G()->close_flag()) {
+    return;
+  }
+
+  auto messages_manager = static_cast<MessagesManager *>(messages_manager_ptr);
+  DialogId dialog_id(dialog_id_int);
+  auto d = messages_manager->get_dialog(dialog_id);
+  CHECK(d != nullptr);
+  CHECK(!d->pending_viewed_message_ids.empty());
+
+  const size_t MAX_MESSAGE_VIEWS = 100;  // server side limit
+  vector<MessageId> message_ids;
+  message_ids.reserve(min(d->pending_viewed_message_ids.size(), MAX_MESSAGE_VIEWS));
+  for (auto message_id : d->pending_viewed_message_ids) {
+    message_ids.push_back(message_id);
+    if (message_ids.size() >= MAX_MESSAGE_VIEWS) {
+      messages_manager->td_->create_handler<GetMessagesViewsQuery>()->send(dialog_id, std::move(message_ids),
+                                                                           d->increment_view_counter);
+      message_ids.clear();
+    }
+  }
+  if (!message_ids.empty()) {
+    messages_manager->td_->create_handler<GetMessagesViewsQuery>()->send(dialog_id, std::move(message_ids),
+                                                                         d->increment_view_counter);
+  }
+  d->pending_viewed_message_ids.clear();
+  d->increment_view_counter = false;
+}
+
+void MessagesManager::on_pending_draft_message_timeout_callback(void *messages_manager_ptr, int64 dialog_id_int) {
+  if (G()->close_flag()) {
+    return;
+  }
+
+  auto messages_manager = static_cast<MessagesManager *>(messages_manager_ptr);
+  DialogId dialog_id(dialog_id_int);
+  messages_manager->save_dialog_draft_message_on_server(dialog_id);
+}
+
+void MessagesManager::on_pending_updated_dialog_timeout_callback(void *messages_manager_ptr, int64 dialog_id_int) {
+  auto messages_manager = static_cast<MessagesManager *>(messages_manager_ptr);
+  // TODO it is unsafe to save dialog to database before binlog is flushed
+  messages_manager->save_dialog_to_database(DialogId(dialog_id_int));
+}
+
+void MessagesManager::on_pending_unload_dialog_timeout_callback(void *messages_manager_ptr, int64 dialog_id_int) {
+  if (G()->close_flag()) {
+    return;
+  }
+
+  auto messages_manager = static_cast<MessagesManager *>(messages_manager_ptr);
+  messages_manager->unload_dialog(DialogId(dialog_id_int));
+}
+
+void MessagesManager::on_dialog_unmute_timeout_callback(void *messages_manager_ptr, int64 dialog_id_int) {
+  if (G()->close_flag()) {
+    return;
+  }
+
+  auto messages_manager = static_cast<MessagesManager *>(messages_manager_ptr);
+  send_closure_later(messages_manager->actor_id(messages_manager), &MessagesManager::on_dialog_unmute,
+                     DialogId(dialog_id_int));
+}
+
+void MessagesManager::on_pending_send_dialog_action_timeout_callback(void *messages_manager_ptr, int64 dialog_id_int) {
+  if (G()->close_flag()) {
+    return;
+  }
+
+  auto messages_manager = static_cast<MessagesManager *>(messages_manager_ptr);
+  send_closure_later(messages_manager->actor_id(messages_manager), &MessagesManager::on_send_dialog_action_timeout,
+                     DialogId(dialog_id_int));
+}
+
+void MessagesManager::on_active_dialog_action_timeout_callback(void *messages_manager_ptr, int64 dialog_id_int) {
+  if (G()->close_flag()) {
+    return;
+  }
+
+  auto messages_manager = static_cast<MessagesManager *>(messages_manager_ptr);
+  send_closure_later(messages_manager->actor_id(messages_manager), &MessagesManager::on_active_dialog_action_timeout,
+                     DialogId(dialog_id_int));
+}
+
+BufferSlice MessagesManager::get_dialog_database_value(const Dialog *d) {
+  // can't use log_event_store, because it tries to parse stored Dialog
+  LogEventStorerCalcLength storer_calc_length;
+  store(*d, storer_calc_length);
+
+  BufferSlice value_buffer{storer_calc_length.get_length()};
+  auto value = value_buffer.as_slice();
+
+  LogEventStorerUnsafe storer_unsafe(value.begin());
+  store(*d, storer_unsafe);
+  return value_buffer;
+}
+
+void MessagesManager::save_dialog_to_database(DialogId dialog_id) {
+  CHECK(G()->parameters().use_message_db);
+  auto d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+  LOG(INFO) << "Save " << dialog_id << " to database";
+  G()->td_db()->get_dialog_db_async()->add_dialog(
+      dialog_id, d->order, get_dialog_database_value(d), PromiseCreator::lambda([dialog_id](Result<> result) {
+        send_closure(G()->messages_manager(), &MessagesManager::on_save_dialog_to_database, dialog_id, result.is_ok());
+      }));
+}
+
+void MessagesManager::on_save_dialog_to_database(DialogId dialog_id, bool success) {
+  LOG(INFO) << "Successfully saved " << dialog_id << " to database";
+  // TODO erase some events from binlog
+}
+
+void MessagesManager::update_message_count_by_index(Dialog *d, int diff, const Message *m) {
+  auto index_mask = get_message_index_mask(d->dialog_id, m);
+  index_mask &= ~search_messages_filter_index_mask(
+      SearchMessagesFilter::UnreadMention);  // unread mention count has been already manually updated
+  if (index_mask == 0) {
+    return;
+  }
+
+  int i = 0;
+  for (auto &message_count : d->message_count_by_index) {
+    if (((index_mask >> i) & 1) != 0 && message_count != -1) {
+      message_count += diff;
+      if (message_count < 0) {
+        if (d->dialog_id.get_type() == DialogType::SecretChat) {
+          message_count = 0;
+        } else {
+          message_count = -1;
+        }
+      }
+      on_dialog_updated(d->dialog_id, "update_message_count_by_index");
+    }
+    i++;
+  }
+
+  i = static_cast<int>(SearchMessagesFilter::Call) - 1;
+  for (auto &message_count : calls_db_state_.message_count_by_index) {
+    if (((index_mask >> i) & 1) != 0 && message_count != -1) {
+      message_count += diff;
+      if (message_count < 0) {
+        if (d->dialog_id.get_type() == DialogType::SecretChat) {
+          message_count = 0;
+        } else {
+          message_count = -1;
+        }
+      }
+      save_calls_db_state();
+    }
+    i++;
+  }
+}
+
+int32 MessagesManager::get_message_index_mask(DialogId dialog_id, const Message *m) const {
+  CHECK(m != nullptr);
+  if (m->message_id.is_yet_unsent() || m->is_failed_to_send) {
+    return 0;
+  }
+  bool is_secret = dialog_id.get_type() == DialogType::SecretChat;
+  if (!m->message_id.is_server() && !is_secret) {
+    return 0;
+  }
+  // retain second condition just in case
+  if (m->is_content_secret || (m->ttl > 0 && !is_secret)) {
+    return 0;
+  }
+  int32 mentions_mask = get_message_content_index_mask(m->content.get(), is_secret, m->is_outgoing);
+  if (m->contains_mention) {
+    mentions_mask |= search_messages_filter_index_mask(SearchMessagesFilter::Mention);
+    if (m->contains_unread_mention) {
+      mentions_mask |= search_messages_filter_index_mask(SearchMessagesFilter::UnreadMention);
+    }
+  }
+  return mentions_mask;
+}
+
+int32 MessagesManager::get_message_content_index_mask(const MessageContent *content, bool is_secret,
+                                                      bool is_outgoing) const {
+  switch (content->get_id()) {
+    case MessageAnimation::ID:
+      return search_messages_filter_index_mask(SearchMessagesFilter::Animation);
+    case MessageAudio::ID: {
+      auto message_audio = static_cast<const MessageAudio *>(content);
+      auto duration = td_->audios_manager_->get_audio_duration(message_audio->file_id);
+      return is_secret || duration > 0 ? search_messages_filter_index_mask(SearchMessagesFilter::Audio)
+                                       : search_messages_filter_index_mask(SearchMessagesFilter::Document);
+    }
+    case MessageDocument::ID:
+      return search_messages_filter_index_mask(SearchMessagesFilter::Document);
+    case MessagePhoto::ID:
+      return search_messages_filter_index_mask(SearchMessagesFilter::Photo) |
+             search_messages_filter_index_mask(SearchMessagesFilter::PhotoAndVideo);
+    case MessageText::ID:
+      for (auto &entity : static_cast<const MessageText *>(content)->text.entities) {
+        if (entity.type == MessageEntity::Type::Url || entity.type == MessageEntity::Type::EmailAddress) {
+          return search_messages_filter_index_mask(SearchMessagesFilter::Url);
+        }
+      }
+      return 0;
+    case MessageVideo::ID: {
+      auto message_video = static_cast<const MessageVideo *>(content);
+      auto duration = td_->videos_manager_->get_video_duration(message_video->file_id);
+      return is_secret || duration > 0 ? search_messages_filter_index_mask(SearchMessagesFilter::Video) |
+                                             search_messages_filter_index_mask(SearchMessagesFilter::PhotoAndVideo)
+                                       : search_messages_filter_index_mask(SearchMessagesFilter::Document);
+    }
+    case MessageVideoNote::ID: {
+      auto message_video_note = static_cast<const MessageVideoNote *>(content);
+      auto duration = td_->video_notes_manager_->get_video_note_duration(message_video_note->file_id);
+      return is_secret || duration > 0 ? search_messages_filter_index_mask(SearchMessagesFilter::VideoNote) |
+                                             search_messages_filter_index_mask(SearchMessagesFilter::VoiceAndVideoNote)
+                                       : search_messages_filter_index_mask(SearchMessagesFilter::Document);
+    }
+    case MessageVoiceNote::ID:
+      return search_messages_filter_index_mask(SearchMessagesFilter::VoiceNote) |
+             search_messages_filter_index_mask(SearchMessagesFilter::VoiceAndVideoNote);
+    case MessageChatChangePhoto::ID:
+      return search_messages_filter_index_mask(SearchMessagesFilter::ChatPhoto);
+    case MessageCall::ID: {
+      int32 index_mask = search_messages_filter_index_mask(SearchMessagesFilter::Call);
+      auto message_call = static_cast<const MessageCall *>(content);
+      if (!is_outgoing && (message_call->discard_reason == CallDiscardReason::Declined ||
+                           message_call->discard_reason == CallDiscardReason::Missed)) {
+        index_mask |= search_messages_filter_index_mask(SearchMessagesFilter::MissedCall);
+      }
+      return index_mask;
+    }
+    case MessageContact::ID:
+    case MessageGame::ID:
+    case MessageInvoice::ID:
+    case MessageLiveLocation::ID:
+    case MessageLocation::ID:
+    case MessageSticker::ID:
+    case MessageUnsupported::ID:
+    case MessageVenue::ID:
+    case MessageChatCreate::ID:
+    case MessageChatChangeTitle::ID:
+    case MessageChatDeletePhoto::ID:
+    case MessageChatDeleteHistory::ID:
+    case MessageChatAddUsers::ID:
+    case MessageChatJoinedByLink::ID:
+    case MessageChatDeleteUser::ID:
+    case MessageChatMigrateTo::ID:
+    case MessageChannelCreate::ID:
+    case MessageChannelMigrateFrom::ID:
+    case MessagePinMessage::ID:
+    case MessageGameScore::ID:
+    case MessageScreenshotTaken::ID:
+    case MessageChatSetTtl::ID:
+    case MessagePaymentSuccessful::ID:
+    case MessageContactRegistered::ID:
+    case MessageExpiredPhoto::ID:
+    case MessageExpiredVideo::ID:
+    case MessageCustomServiceAction::ID:
+    case MessageWebsiteConnected::ID:
+      return 0;
+    default:
+      UNREACHABLE();
+      return 0;
+  }
+  return 0;
+}
+
+vector<MessageId> MessagesManager::get_message_ids(const vector<int64> &input_message_ids) {
+  vector<MessageId> message_ids;
+  message_ids.reserve(input_message_ids.size());
+  for (auto &input_message_id : input_message_ids) {
+    message_ids.push_back(MessageId(input_message_id));
+  }
+  return message_ids;
+}
+
+vector<int32> MessagesManager::get_server_message_ids(const vector<MessageId> &message_ids) {
+  return transform(message_ids, [](MessageId message_id) { return message_id.get_server_message_id().get(); });
+}
+
+tl_object_ptr<telegram_api::InputMessage> MessagesManager::get_input_message(MessageId message_id) {
+  return make_tl_object<telegram_api::inputMessageID>(message_id.get_server_message_id().get());
+}
+
+tl_object_ptr<telegram_api::InputPeer> MessagesManager::get_input_peer(DialogId dialog_id,
+                                                                       AccessRights access_rights) const {
+  switch (dialog_id.get_type()) {
+    case DialogType::User: {
+      UserId user_id = dialog_id.get_user_id();
+      return td_->contacts_manager_->get_input_peer_user(user_id, access_rights);
+    }
+    case DialogType::Chat: {
+      ChatId chat_id = dialog_id.get_chat_id();
+      return td_->contacts_manager_->get_input_peer_chat(chat_id, access_rights);
+    }
+    case DialogType::Channel: {
+      ChannelId channel_id = dialog_id.get_channel_id();
+      return td_->contacts_manager_->get_input_peer_channel(channel_id, access_rights);
+    }
+    case DialogType::SecretChat:
+      return nullptr;
+    case DialogType::None:
+      return make_tl_object<telegram_api::inputPeerEmpty>();
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+vector<tl_object_ptr<telegram_api::InputPeer>> MessagesManager::get_input_peers(const vector<DialogId> &dialog_ids,
+                                                                                AccessRights access_rights) const {
+  vector<tl_object_ptr<telegram_api::InputPeer>> input_peers;
+  input_peers.reserve(dialog_ids.size());
+  for (auto &dialog_id : dialog_ids) {
+    auto input_peer = get_input_peer(dialog_id, access_rights);
+    if (input_peer == nullptr) {
+      LOG(ERROR) << "Have no access to " << dialog_id;
+      continue;
+    }
+    input_peers.push_back(std::move(input_peer));
+  }
+  return input_peers;
+}
+
+tl_object_ptr<telegram_api::inputDialogPeer> MessagesManager::get_input_dialog_peer(DialogId dialog_id,
+                                                                                    AccessRights access_rights) const {
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+    case DialogType::Channel:
+    case DialogType::None:
+      return make_tl_object<telegram_api::inputDialogPeer>(get_input_peer(dialog_id, access_rights));
+    case DialogType::SecretChat:
+      return nullptr;
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+vector<tl_object_ptr<telegram_api::inputDialogPeer>> MessagesManager::get_input_dialog_peers(
+    const vector<DialogId> &dialog_ids, AccessRights access_rights) const {
+  vector<tl_object_ptr<telegram_api::inputDialogPeer>> input_dialog_peers;
+  input_dialog_peers.reserve(dialog_ids.size());
+  for (auto &dialog_id : dialog_ids) {
+    auto input_dialog_peer = get_input_dialog_peer(dialog_id, access_rights);
+    if (input_dialog_peer == nullptr) {
+      LOG(ERROR) << "Have no access to " << dialog_id;
+      continue;
+    }
+    input_dialog_peers.push_back(std::move(input_dialog_peer));
+  }
+  return input_dialog_peers;
+}
+
+bool MessagesManager::have_input_peer(DialogId dialog_id, AccessRights access_rights) const {
+  switch (dialog_id.get_type()) {
+    case DialogType::User: {
+      UserId user_id = dialog_id.get_user_id();
+      return td_->contacts_manager_->have_input_peer_user(user_id, access_rights);
+    }
+    case DialogType::Chat: {
+      ChatId chat_id = dialog_id.get_chat_id();
+      return td_->contacts_manager_->have_input_peer_chat(chat_id, access_rights);
+    }
+    case DialogType::Channel: {
+      ChannelId channel_id = dialog_id.get_channel_id();
+      return td_->contacts_manager_->have_input_peer_channel(channel_id, access_rights);
+    }
+    case DialogType::SecretChat: {
+      SecretChatId secret_chat_id = dialog_id.get_secret_chat_id();
+      return td_->contacts_manager_->have_input_encrypted_peer(secret_chat_id, access_rights);
+    }
+    case DialogType::None:
+      return false;
+    default:
+      UNREACHABLE();
+      return false;
+  }
+}
+
+bool MessagesManager::have_dialog_info(DialogId dialog_id) const {
+  switch (dialog_id.get_type()) {
+    case DialogType::User: {
+      UserId user_id = dialog_id.get_user_id();
+      return td_->contacts_manager_->have_user(user_id);
+    }
+    case DialogType::Chat: {
+      ChatId chat_id = dialog_id.get_chat_id();
+      return td_->contacts_manager_->have_chat(chat_id);
+    }
+    case DialogType::Channel: {
+      ChannelId channel_id = dialog_id.get_channel_id();
+      return td_->contacts_manager_->have_channel(channel_id);
+    }
+    case DialogType::SecretChat: {
+      SecretChatId secret_chat_id = dialog_id.get_secret_chat_id();
+      return td_->contacts_manager_->have_secret_chat(secret_chat_id);
+    }
+    case DialogType::None:
+    default:
+      return false;
+  }
+}
+
+bool MessagesManager::have_dialog_info_force(DialogId dialog_id) const {
+  switch (dialog_id.get_type()) {
+    case DialogType::User: {
+      UserId user_id = dialog_id.get_user_id();
+      return td_->contacts_manager_->have_user_force(user_id);
+    }
+    case DialogType::Chat: {
+      ChatId chat_id = dialog_id.get_chat_id();
+      return td_->contacts_manager_->have_chat_force(chat_id);
+    }
+    case DialogType::Channel: {
+      ChannelId channel_id = dialog_id.get_channel_id();
+      return td_->contacts_manager_->have_channel_force(channel_id);
+    }
+    case DialogType::SecretChat: {
+      SecretChatId secret_chat_id = dialog_id.get_secret_chat_id();
+      return td_->contacts_manager_->have_secret_chat_force(secret_chat_id);
+    }
+    case DialogType::None:
+    default:
+      return false;
+  }
+}
+
+tl_object_ptr<telegram_api::inputEncryptedChat> MessagesManager::get_input_encrypted_chat(
+    DialogId dialog_id, AccessRights access_rights) const {
+  switch (dialog_id.get_type()) {
+    case DialogType::SecretChat: {
+      SecretChatId secret_chat_id = dialog_id.get_secret_chat_id();
+      return td_->contacts_manager_->get_input_encrypted_chat(secret_chat_id, access_rights);
+    }
+    case DialogType::User:
+    case DialogType::Chat:
+    case DialogType::Channel:
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+bool MessagesManager::is_allowed_useless_update(const tl_object_ptr<telegram_api::Update> &update) const {
+  auto constructor_id = update->get_id();
+  if (constructor_id == dummyUpdate::ID) {
+    // allow dummyUpdate just in case
+    return true;
+  }
+  if (constructor_id == telegram_api::updateNewMessage::ID) {
+    auto message = static_cast<const telegram_api::updateNewMessage *>(update.get())->message_.get();
+    if (message->get_id() == telegram_api::message::ID) {
+      auto m = static_cast<const telegram_api::message *>(message);
+      bool is_outgoing = (m->flags_ & MESSAGE_FLAG_IS_OUT) != 0 ||
+                         UserId(m->from_id_) == td_->contacts_manager_->get_my_id("is_allowed_useless_update");
+      if (is_outgoing && m->media_ != nullptr && m->media_->get_id() != telegram_api::messageMediaEmpty::ID) {
+        // allow outgoing media, because they are returned if random_id coincided
+        return true;
+      }
+    }
+    if (message->get_id() == telegram_api::messageService::ID) {
+      auto m = static_cast<const telegram_api::messageService *>(message);
+      bool is_outgoing = (m->flags_ & MESSAGE_FLAG_IS_OUT) != 0 ||
+                         UserId(m->from_id_) == td_->contacts_manager_->get_my_id("is_allowed_useless_update");
+      if (is_outgoing && m->action_->get_id() == telegram_api::messageActionScreenshotTaken::ID) {
+        // allow outgoing messageActionScreenshotTaken, because they are returned if random_id coincided
+        return true;
+      }
+    }
+  }
+
+  return false;
+}
+
+bool MessagesManager::check_update_dialog_id(const tl_object_ptr<telegram_api::Update> &update, DialogId dialog_id) {
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+      return true;
+    case DialogType::Channel:
+    case DialogType::SecretChat:
+    case DialogType::None:
+      LOG(ERROR) << "Receive update in wrong " << dialog_id << ": " << oneline(to_string(update));
+      return false;
+    default:
+      UNREACHABLE();
+      return false;
+  }
+}
+
+void MessagesManager::skip_old_pending_update(tl_object_ptr<telegram_api::Update> &&update, int32 new_pts,
+                                              int32 old_pts, int32 pts_count, const char *source) {
+  if (update->get_id() == telegram_api::updateNewMessage::ID) {
+    auto update_new_message = static_cast<telegram_api::updateNewMessage *>(update.get());
+    auto full_message_id = get_full_message_id(update_new_message->message_);
+    if (update_message_ids_.find(full_message_id) != update_message_ids_.end()) {
+      if (new_pts == old_pts) {  // otherwise message can be already deleted
+        // apply sent message anyway
+        on_get_message(std::move(update_new_message->message_), true, false, true, true,
+                       "updateNewMessage with an awaited message");
+        return;
+      } else {
+        LOG(ERROR) << "Receive awaited sent " << full_message_id << " from " << source << " with pts " << new_pts
+                   << " and pts_count " << pts_count << ", but current pts is " << old_pts;
+        dump_debug_message_op(get_dialog(full_message_id.get_dialog_id()), 3);
+      }
+    }
+  }
+  if (update->get_id() == updateSentMessage::ID) {
+    auto update_sent_message = static_cast<updateSentMessage *>(update.get());
+    if (being_sent_messages_.count(update_sent_message->random_id_) > 0) {
+      if (new_pts == old_pts) {  // otherwise message can be already deleted
+        // apply sent message anyway
+        on_send_message_success(update_sent_message->random_id_, update_sent_message->message_id_,
+                                update_sent_message->date_, FileId(), "process old updateSentMessage");
+        return;
+      } else {
+        LOG(ERROR) << "Receive awaited sent " << update_sent_message->message_id_ << " from " << source << " with pts "
+                   << new_pts << " and pts_count " << pts_count << ", but current pts is " << old_pts;
+        dump_debug_message_op(get_dialog(being_sent_messages_[update_sent_message->random_id_].get_dialog_id()), 3);
+      }
+    }
+    return;
+  }
+
+  // very old or unuseful update
+  LOG_IF(WARNING, new_pts == old_pts && pts_count == 0 && !is_allowed_useless_update(update))
+      << "Receive useless update " << oneline(to_string(update)) << " from " << source;
+}
+
+void MessagesManager::add_pending_update(tl_object_ptr<telegram_api::Update> &&update, int32 new_pts, int32 pts_count,
+                                         bool force_apply, const char *source) {
+  // do not try to run getDifference from this function
+  CHECK(update != nullptr);
+  CHECK(source != nullptr);
+  LOG(INFO) << "Receive from " << source << " pending " << to_string(update) << "new_pts = " << new_pts
+            << ", pts_count = " << pts_count << ", force_apply = " << force_apply;
+  if (pts_count < 0 || new_pts <= pts_count) {
+    LOG(ERROR) << "Receive update with wrong pts = " << new_pts << " or pts_count = " << pts_count << " from " << source
+               << ": " << oneline(to_string(update));
+    return;
+  }
+
+  // TODO need to save all updates that can change result of running queries not associated with pts (for example
+  // getHistory) and apply them to result of this queries
+
+  switch (update->get_id()) {
+    case dummyUpdate::ID:
+    case updateSentMessage::ID:
+    case telegram_api::updateReadMessagesContents::ID:
+    case telegram_api::updateDeleteMessages::ID:
+      // nothing to check
+      break;
+    case telegram_api::updateNewMessage::ID: {
+      auto update_new_message = static_cast<const telegram_api::updateNewMessage *>(update.get());
+      DialogId dialog_id = get_message_dialog_id(update_new_message->message_);
+      if (!check_update_dialog_id(update, dialog_id)) {
+        return;
+      }
+      break;
+    }
+    case telegram_api::updateReadHistoryInbox::ID: {
+      auto update_read_history_inbox = static_cast<const telegram_api::updateReadHistoryInbox *>(update.get());
+      auto dialog_id = DialogId(update_read_history_inbox->peer_);
+      if (!check_update_dialog_id(update, dialog_id)) {
+        return;
+      }
+      break;
+    }
+    case telegram_api::updateReadHistoryOutbox::ID: {
+      auto update_read_history_outbox = static_cast<const telegram_api::updateReadHistoryOutbox *>(update.get());
+      auto dialog_id = DialogId(update_read_history_outbox->peer_);
+      if (!check_update_dialog_id(update, dialog_id)) {
+        return;
+      }
+      break;
+    }
+    case telegram_api::updateEditMessage::ID: {
+      auto update_edit_message = static_cast<const telegram_api::updateEditMessage *>(update.get());
+      DialogId dialog_id = get_message_dialog_id(update_edit_message->message_);
+      if (!check_update_dialog_id(update, dialog_id)) {
+        return;
+      }
+      break;
+    }
+    default:
+      LOG(ERROR) << "Receive unexpected update " << oneline(to_string(update)) << "from " << source;
+      return;
+  }
+
+  if (force_apply) {
+    CHECK(pending_updates_.empty());
+    CHECK(accumulated_pts_ == -1);
+    if (pts_count != 0) {
+      LOG(ERROR) << "Receive forced update with pts_count = " << pts_count << " from " << source;
+    }
+
+    process_update(std::move(update));
+    return;
+  }
+  if (DROP_UPDATES) {
+    return set_get_difference_timeout(1.0);
+  }
+
+  int32 old_pts = td_->updates_manager_->get_pts();
+  if (new_pts < old_pts - 19999) {
+    // restore pts after delete_first_messages
+    LOG(ERROR) << "Restore pts after delete_first_messages from " << old_pts << " to " << new_pts
+               << " is temporarily disabled, pts_count = " << pts_count << ", update is from " << source << ": "
+               << oneline(to_string(update));
+    if (old_pts < 10000000 && update->get_id() == telegram_api::updateNewMessage::ID) {
+      auto update_new_message = static_cast<telegram_api::updateNewMessage *>(update.get());
+      auto dialog_id = get_message_dialog_id(update_new_message->message_);
+      dump_debug_message_op(get_dialog(dialog_id), 6);
+    }
+    set_get_difference_timeout(0.001);
+
+    /*
+    LOG(WARNING) << "Restore pts after delete_first_messages";
+    td_->updates_manager_->set_pts(new_pts - 1, "restore pts after delete_first_messages");
+    old_pts = td_->updates_manager_->get_pts();
+    CHECK(old_pts == new_pts - 1);
+    */
+  }
+
+  if (new_pts <= old_pts) {
+    skip_old_pending_update(std::move(update), new_pts, old_pts, pts_count, source);
+    return;
+  }
+
+  if (td_->updates_manager_->running_get_difference()) {
+    LOG(INFO) << "Save pending update got while running getDifference from " << source;
+    CHECK(update->get_id() == dummyUpdate::ID || update->get_id() == updateSentMessage::ID);
+    if (pts_count > 0) {
+      postponed_pts_updates_.emplace(new_pts, PendingPtsUpdate(std::move(update), new_pts, pts_count));
+    }
+    return;
+  }
+
+  if (old_pts + pts_count > new_pts) {
+    LOG(WARNING) << "old_pts (= " << old_pts << ") + pts_count (= " << pts_count << ") > new_pts (= " << new_pts
+                 << "). Logged in " << G()->shared_config().get_option_integer("authorization_date") << ". Update from "
+                 << source << " = " << oneline(to_string(update));
+    set_get_difference_timeout(0.001);
+    return;
+  }
+
+  accumulated_pts_count_ += pts_count;
+  if (new_pts > accumulated_pts_) {
+    accumulated_pts_ = new_pts;
+  }
+
+  if (old_pts + accumulated_pts_count_ > accumulated_pts_) {
+    LOG(WARNING) << "old_pts (= " << old_pts << ") + accumulated_pts_count (= " << accumulated_pts_count_
+                 << ") > accumulated_pts (= " << accumulated_pts_ << "). new_pts = " << new_pts
+                 << ", pts_count = " << pts_count << ". Logged in "
+                 << G()->shared_config().get_option_integer("authorization_date") << ". Update from " << source << " = "
+                 << oneline(to_string(update));
+    set_get_difference_timeout(0.001);
+    return;
+  }
+
+  LOG_IF(INFO, pts_count == 0 && update->get_id() != dummyUpdate::ID) << "Skip useless update " << to_string(update);
+
+  if (pending_updates_.empty() && old_pts + accumulated_pts_count_ == accumulated_pts_ &&
+      !pts_gap_timeout_.has_timeout()) {
+    if (pts_count > 0) {
+      process_update(std::move(update));
+
+      td_->updates_manager_->set_pts(accumulated_pts_, "process pending updates fast path")
+          .set_value(Unit());  // TODO can't set until get messages really stored on persistent storage
+      accumulated_pts_count_ = 0;
+      accumulated_pts_ = -1;
+    }
+    return;
+  }
+
+  if (pts_count > 0) {
+    pending_updates_.emplace(new_pts, PendingPtsUpdate(std::move(update), new_pts, pts_count));
+  }
+
+  if (old_pts + accumulated_pts_count_ < accumulated_pts_) {
+    set_get_difference_timeout(UpdatesManager::MAX_UNFILLED_GAP_TIME);
+    return;
+  }
+
+  CHECK(old_pts + accumulated_pts_count_ == accumulated_pts_);
+  if (!pending_updates_.empty()) {
+    process_pending_updates();
+  }
+}
+
+MessagesManager::Dialog *MessagesManager::get_service_notifications_dialog() {
+  UserId service_notifications_user_id(777000);
+  if (!td_->contacts_manager_->have_user_force(service_notifications_user_id) ||
+      !td_->contacts_manager_->have_user(service_notifications_user_id)) {
+    auto user = telegram_api::make_object<telegram_api::user>(
+        131127, false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/,
+        false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/,
+        false /*ignored*/, 777000, 1, "Telegram", "Updates", string(), "42777",
+        telegram_api::make_object<telegram_api::userProfilePhoto>(
+            3337190045231018,
+            telegram_api::make_object<telegram_api::fileLocation>(1, 702229962, 26779, 5859320227133863146),
+            telegram_api::make_object<telegram_api::fileLocation>(1, 702229962, 26781, -3695031185685824216)),
+        nullptr, 0, string(), string(), string());
+    td_->contacts_manager_->on_get_user(std::move(user));
+  }
+  DialogId service_notifications_dialog_id(service_notifications_user_id);
+  force_create_dialog(service_notifications_dialog_id, "get_service_notifications_dialog");
+  return get_dialog(service_notifications_dialog_id);
+}
+
+void MessagesManager::on_update_service_notification(tl_object_ptr<telegram_api::updateServiceNotification> &&update) {
+  int32 ttl = 0;
+  auto content = get_message_content(
+      get_message_text(std::move(update->message_), std::move(update->entities_), update->inbox_date_),
+      std::move(update->media_),
+      td_->auth_manager_->is_bot() ? DialogId() : get_service_notifications_dialog()->dialog_id, false, UserId(), &ttl);
+  bool is_content_secret = is_secret_message_content(ttl, content->get_id());
+  if ((update->flags_ & telegram_api::updateServiceNotification::POPUP_MASK) != 0) {
+    send_closure(G()->td(), &Td::send_update,
+                 make_tl_object<td_api::updateServiceNotification>(
+                     update->type_, get_message_content_object(content.get(), update->inbox_date_, is_content_secret)));
+  }
+  if ((update->flags_ & telegram_api::updateServiceNotification::INBOX_DATE_MASK) != 0 &&
+      !td_->auth_manager_->is_bot()) {
+    Dialog *d = get_service_notifications_dialog();
+    CHECK(d != nullptr);
+    auto dialog_id = d->dialog_id;
+    CHECK(dialog_id.get_type() == DialogType::User);
+    auto new_message = make_unique<Message>();
+    new_message->message_id = get_next_local_message_id(d);
+    new_message->random_y = get_random_y(new_message->message_id);
+    new_message->sender_user_id = dialog_id.get_user_id();
+    new_message->date = update->inbox_date_;
+    new_message->ttl = ttl;
+    new_message->is_content_secret = is_content_secret;
+    new_message->content = std::move(content);
+    new_message->have_previous = true;
+    new_message->have_next = true;
+
+    bool need_update = true;
+    bool need_update_dialog_pos = false;
+
+    Message *m = add_message_to_dialog(d, std::move(new_message), true, &need_update, &need_update_dialog_pos,
+                                       "on_update_service_notification");
+    if (m != nullptr && need_update) {
+      send_update_new_message(d, m);
+    }
+
+    if (need_update_dialog_pos) {
+      send_update_chat_last_message(d, "on_update_service_notification");
+    }
+  }
+}
+
+void MessagesManager::on_update_contact_registered(tl_object_ptr<telegram_api::updateContactRegistered> &&update) {
+  if (update->date_ <= 0) {
+    LOG(ERROR) << "Receive wrong date " << update->date_ << " in updateContactRegistered";
+    return;
+  }
+  UserId user_id(update->user_id_);
+  if (!user_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << user_id << " in updateContactRegistered";
+    return;
+  }
+
+  if (!td_->auth_manager_->is_bot() &&
+      !G()->shared_config().get_option_boolean("disable_contact_registered_notifications")) {
+    DialogId dialog_id(user_id);
+    force_create_dialog(dialog_id, "on_update_contact_registered");
+    Dialog *d = get_dialog(dialog_id);
+    CHECK(d != nullptr);
+
+    if (d->has_contact_registered_message) {
+      LOG(INFO) << "Ignore duplicate updateContactRegistered about " << user_id;
+      return;
+    }
+    if (d->last_message_id.is_valid()) {
+      auto m = get_message(d, d->last_message_id);
+      CHECK(m != nullptr);
+      if (m->content->get_id() == MessageContactRegistered::ID) {
+        LOG(INFO) << "Ignore duplicate updateContactRegistered about " << user_id;
+        return;
+      }
+    }
+
+    auto new_message = make_unique<Message>();
+    new_message->message_id = get_next_local_message_id(d);
+    new_message->random_y = get_random_y(new_message->message_id);
+    new_message->sender_user_id = user_id;
+    new_message->date = update->date_;
+    new_message->content = make_unique<MessageContactRegistered>();
+    new_message->have_previous = true;
+    new_message->have_next = true;
+
+    bool need_update = true;
+    bool need_update_dialog_pos = false;
+
+    Message *m = add_message_to_dialog(d, std::move(new_message), true, &need_update, &need_update_dialog_pos,
+                                       "on_update_contact_registered");
+    if (m != nullptr && need_update) {
+      send_update_new_message(d, m);
+    }
+
+    if (need_update_dialog_pos) {
+      send_update_chat_last_message(d, "on_update_contact_registered");
+    }
+  }
+}
+
+void MessagesManager::on_update_new_channel_message(tl_object_ptr<telegram_api::updateNewChannelMessage> &&update) {
+  int new_pts = update->pts_;
+  int pts_count = update->pts_count_;
+  DialogId dialog_id = get_message_dialog_id(update->message_);
+  switch (dialog_id.get_type()) {
+    case DialogType::None:
+      return;
+    case DialogType::User:
+    case DialogType::Chat:
+    case DialogType::SecretChat:
+      LOG(ERROR) << "Receive updateNewChannelMessage in wrong " << dialog_id;
+      return;
+    case DialogType::Channel: {
+      auto channel_id = dialog_id.get_channel_id();
+      if (!td_->contacts_manager_->have_channel(channel_id)) {
+        // if min channel was received
+        if (td_->contacts_manager_->have_min_channel(channel_id)) {
+          td_->updates_manager_->schedule_get_difference("on_update_new_channel_message");
+          return;
+        }
+      }
+      // Ok
+      break;
+    }
+    default:
+      UNREACHABLE();
+      return;
+  }
+
+  if (pts_count < 0 || new_pts <= pts_count) {
+    LOG(ERROR) << "Receive new channel message with wrong pts = " << new_pts << " or pts_count = " << pts_count << ": "
+               << oneline(to_string(update));
+    return;
+  }
+
+  add_pending_channel_update(dialog_id, std::move(update), new_pts, pts_count, "on_update_new_channel_message");
+}
+
+void MessagesManager::on_update_edit_channel_message(tl_object_ptr<telegram_api::updateEditChannelMessage> &&update) {
+  int new_pts = update->pts_;
+  int pts_count = update->pts_count_;
+  DialogId dialog_id = get_message_dialog_id(update->message_);
+  switch (dialog_id.get_type()) {
+    case DialogType::None:
+      return;
+    case DialogType::User:
+    case DialogType::Chat:
+    case DialogType::SecretChat:
+      LOG(ERROR) << "Receive updateNewChannelMessage in wrong " << dialog_id;
+      return;
+    case DialogType::Channel: {
+      auto channel_id = dialog_id.get_channel_id();
+      if (!td_->contacts_manager_->have_channel(channel_id)) {
+        // if min channel was received
+        if (td_->contacts_manager_->have_min_channel(channel_id)) {
+          td_->updates_manager_->schedule_get_difference("on_update_edit_channel_message");
+          return;
+        }
+      }
+      // Ok
+      break;
+    }
+    default:
+      UNREACHABLE();
+      return;
+  }
+
+  if (pts_count < 0 || new_pts <= pts_count) {
+    LOG(ERROR) << "Receive edited channel message with wrong pts = " << new_pts << " or pts_count = " << pts_count
+               << ": " << oneline(to_string(update));
+    return;
+  }
+
+  add_pending_channel_update(dialog_id, std::move(update), new_pts, pts_count, "on_update_edit_channel_message");
+}
+
+void MessagesManager::on_update_read_channel_inbox(tl_object_ptr<telegram_api::updateReadChannelInbox> &&update) {
+  ChannelId channel_id(update->channel_id_);
+  if (!channel_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << channel_id << " in updateReadChannelInbox";
+    return;
+  }
+
+  DialogId dialog_id = DialogId(channel_id);
+  read_history_inbox(dialog_id, MessageId(ServerMessageId(update->max_id_)), -1, "updateReadChannelInbox");
+}
+
+void MessagesManager::on_update_read_channel_outbox(tl_object_ptr<telegram_api::updateReadChannelOutbox> &&update) {
+  ChannelId channel_id(update->channel_id_);
+  if (!channel_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << channel_id << " in updateReadChannelOutbox";
+    return;
+  }
+
+  DialogId dialog_id = DialogId(channel_id);
+  read_history_outbox(dialog_id, MessageId(ServerMessageId(update->max_id_)));
+}
+
+void MessagesManager::on_update_read_channel_messages_contents(
+    tl_object_ptr<telegram_api::updateChannelReadMessagesContents> &&update) {
+  ChannelId channel_id(update->channel_id_);
+  if (!channel_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << channel_id << " in updateChannelReadMessagesContents";
+    return;
+  }
+
+  DialogId dialog_id = DialogId(channel_id);
+
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    LOG(INFO) << "Receive read channel messages contents update in unknown " << dialog_id;
+    return;
+  }
+
+  for (auto &server_message_id : update->messages_) {
+    read_channel_message_content_from_updates(d, MessageId(ServerMessageId(server_message_id)));
+  }
+}
+
+void MessagesManager::on_update_channel_too_long(tl_object_ptr<telegram_api::updateChannelTooLong> &&update,
+                                                 bool force_apply) {
+  ChannelId channel_id(update->channel_id_);
+  if (!channel_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << channel_id << " in updateChannelTooLong";
+    return;
+  }
+
+  DialogId dialog_id = DialogId(channel_id);
+  auto d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    auto pts = load_channel_pts(dialog_id);
+    if (pts > 0) {
+      d = add_dialog(dialog_id);
+      CHECK(d != nullptr);
+      CHECK(d->pts == pts);
+      update_dialog_pos(d, false, "on_update_channel_too_long");
+    }
+  }
+
+  int32 update_pts = (update->flags_ & UPDATE_CHANNEL_TO_LONG_FLAG_HAS_PTS) ? update->pts_ : 0;
+
+  if (force_apply) {
+    if (d == nullptr) {
+      get_channel_difference(dialog_id, -1, true, "on_update_channel_too_long 1");
+    } else {
+      get_channel_difference(dialog_id, d->pts, true, "on_update_channel_too_long 2");
+    }
+  } else {
+    if (d == nullptr) {
+      td_->updates_manager_->schedule_get_difference("on_update_channel_too_long");
+    } else if (update_pts > d->pts) {
+      get_channel_difference(dialog_id, d->pts, true, "on_update_channel_too_long 3");
+    }
+  }
+}
+
+void MessagesManager::on_update_message_views(FullMessageId full_message_id, int32 views) {
+  auto dialog_id = full_message_id.get_dialog_id();
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    LOG(INFO) << "Ignore updateMessageViews in unknown " << dialog_id;
+    return;
+  }
+  auto message_id = full_message_id.get_message_id();
+  Message *m = get_message_force(d, message_id);
+  if (m == nullptr) {
+    LOG(INFO) << "Ignore updateMessageViews about unknown " << full_message_id;
+    return;
+  }
+
+  if (update_message_views(full_message_id.get_dialog_id(), m, views)) {
+    on_message_changed(d, m, "on_update_message_views");
+  }
+}
+
+bool MessagesManager::update_message_views(DialogId dialog_id, Message *m, int32 views) {
+  CHECK(m != nullptr);
+  if (views > m->views) {
+    m->views = views;
+    send_closure(G()->td(), &Td::send_update,
+                 make_tl_object<td_api::updateMessageViews>(dialog_id.get(), m->message_id.get(), m->views));
+    return true;
+  }
+  return false;
+}
+
+bool MessagesManager::update_message_contains_unread_mention(Dialog *d, Message *m, bool contains_unread_mention,
+                                                             const char *source) {
+  CHECK(m != nullptr) << source;
+  if (!contains_unread_mention && m->contains_unread_mention) {
+    m->contains_unread_mention = false;
+    if (d->unread_mention_count == 0) {
+      LOG_IF(ERROR, d->message_count_by_index[search_messages_filter_index(SearchMessagesFilter::UnreadMention)] != -1)
+          << "Unread mention count of " << d->dialog_id << " became negative from " << source;
+    } else {
+      d->unread_mention_count--;
+      d->message_count_by_index[search_messages_filter_index(SearchMessagesFilter::UnreadMention)] =
+          d->unread_mention_count;
+      on_dialog_updated(d->dialog_id, "update_message_contains_unread_mention");
+    }
+    LOG(INFO) << "Update unread mention message count in " << d->dialog_id << " to " << d->unread_mention_count
+              << " by reading " << m->message_id << " from " << source;
+
+    send_closure(G()->td(), &Td::send_update,
+                 make_tl_object<td_api::updateMessageMentionRead>(d->dialog_id.get(), m->message_id.get(),
+                                                                  d->unread_mention_count));
+    return true;
+  }
+  return false;
+}
+
+void MessagesManager::on_read_channel_inbox(ChannelId channel_id, MessageId max_message_id, int32 server_unread_count) {
+  DialogId dialog_id(channel_id);
+  if (max_message_id.is_valid() || server_unread_count > 0) {
+    /*
+    // dropping unread count can make things worse, so don't drop it
+    if (server_unread_count > 0 && G()->parameters().use_message_db) {
+      const Dialog *d = get_dialog_force(dialog_id);
+      if (d == nullptr) {
+        return;
+      }
+
+      if (d->is_last_read_inbox_message_id_inited) {
+        server_unread_count = -1;
+      }
+    }
+    */
+    read_history_inbox(dialog_id, max_message_id, server_unread_count, "on_read_channel_inbox");
+  }
+}
+
+void MessagesManager::on_read_channel_outbox(ChannelId channel_id, MessageId max_message_id) {
+  DialogId dialog_id(channel_id);
+  if (max_message_id.is_valid()) {
+    read_history_outbox(dialog_id, max_message_id);
+  }
+}
+
+void MessagesManager::on_update_channel_max_unavailable_message_id(ChannelId channel_id,
+                                                                   MessageId max_unavailable_message_id) {
+  if (!channel_id.is_valid()) {
+    LOG(ERROR) << "Receive max_unavailable_message_id in invalid " << channel_id;
+    return;
+  }
+
+  DialogId dialog_id(channel_id);
+  if (!max_unavailable_message_id.is_valid() && max_unavailable_message_id != MessageId()) {
+    LOG(ERROR) << "Receive wrong max_unavailable_message_id: " << max_unavailable_message_id;
+    max_unavailable_message_id = MessageId();
+  }
+  set_dialog_max_unavailable_message_id(dialog_id, max_unavailable_message_id, true,
+                                        "on_update_channel_max_unavailable_message_id");
+}
+
+bool MessagesManager::need_cancel_user_dialog_action(int32 action_id, int32 message_content_id) {
+  if (message_content_id == -1) {
+    return true;
+  }
+
+  if (action_id == td_api::chatActionTyping::ID) {
+    return message_content_id == MessageText::ID || message_content_id == MessageGame::ID ||
+           can_have_message_content_caption(message_content_id);
+  }
+
+  switch (message_content_id) {
+    case MessageAnimation::ID:
+    case MessageAudio::ID:
+    case MessageDocument::ID:
+      return action_id == td_api::chatActionUploadingDocument::ID;
+    case MessageExpiredPhoto::ID:
+    case MessagePhoto::ID:
+      return action_id == td_api::chatActionUploadingPhoto::ID;
+    case MessageExpiredVideo::ID:
+    case MessageVideo::ID:
+      return action_id == td_api::chatActionRecordingVideo::ID || action_id == td_api::chatActionUploadingVideo::ID;
+    case MessageVideoNote::ID:
+      return action_id == td_api::chatActionRecordingVideoNote::ID ||
+             action_id == td_api::chatActionUploadingVideoNote::ID;
+    case MessageVoiceNote::ID:
+      return action_id == td_api::chatActionRecordingVoiceNote::ID ||
+             action_id == td_api::chatActionUploadingVoiceNote::ID;
+    case MessageContact::ID:
+      return action_id == td_api::chatActionChoosingContact::ID;
+    case MessageLiveLocation::ID:
+    case MessageLocation::ID:
+    case MessageVenue::ID:
+      return action_id == td_api::chatActionChoosingLocation::ID;
+    case MessageText::ID:
+    case MessageGame::ID:
+    case MessageUnsupported::ID:
+    case MessageChatCreate::ID:
+    case MessageChatChangeTitle::ID:
+    case MessageChatChangePhoto::ID:
+    case MessageChatDeletePhoto::ID:
+    case MessageChatDeleteHistory::ID:
+    case MessageChatAddUsers::ID:
+    case MessageChatJoinedByLink::ID:
+    case MessageChatDeleteUser::ID:
+    case MessageChatMigrateTo::ID:
+    case MessageChannelCreate::ID:
+    case MessageChannelMigrateFrom::ID:
+    case MessagePinMessage::ID:
+    case MessageGameScore::ID:
+    case MessageScreenshotTaken::ID:
+    case MessageChatSetTtl::ID:
+    case MessageCall::ID:
+    case MessagePaymentSuccessful::ID:
+    case MessageContactRegistered::ID:
+    case MessageCustomServiceAction::ID:
+    case MessageWebsiteConnected::ID:
+      return false;
+    default:
+      UNREACHABLE();
+      return false;
+  }
+}
+
+void MessagesManager::on_user_dialog_action(DialogId dialog_id, UserId user_id,
+                                            tl_object_ptr<td_api::ChatAction> &&action, int32 message_content_id) {
+  if (td_->auth_manager_->is_bot() || !user_id.is_valid() || is_broadcast_channel(dialog_id)) {
+    return;
+  }
+
+  bool is_canceled = action == nullptr || action->get_id() == td_api::chatActionCancel::ID;
+  if (is_canceled) {
+    auto actions_it = active_dialog_actions_.find(dialog_id);
+    if (actions_it == active_dialog_actions_.end()) {
+      return;
+    }
+
+    auto &active_actions = actions_it->second;
+    auto it = std::find_if(active_actions.begin(), active_actions.end(),
+                           [user_id](const ActiveDialogAction &action) { return action.user_id == user_id; });
+    if (it == active_actions.end()) {
+      return;
+    }
+
+    if (!need_cancel_user_dialog_action(it->action_id, message_content_id)) {
+      return;
+    }
+
+    LOG(DEBUG) << "Cancel action of " << user_id << " in " << dialog_id;
+    active_actions.erase(it);
+    if (active_actions.empty()) {
+      active_dialog_actions_.erase(dialog_id);
+      LOG(DEBUG) << "Cancel action timeout in " << dialog_id;
+      active_dialog_action_timeout_.cancel_timeout(dialog_id.get());
+    }
+    if (action == nullptr) {
+      action = make_tl_object<td_api::chatActionCancel>();
+    }
+  } else {
+    auto &active_actions = active_dialog_actions_[dialog_id];
+    auto it = std::find_if(active_actions.begin(), active_actions.end(),
+                           [user_id](const ActiveDialogAction &action) { return action.user_id == user_id; });
+    int32 prev_action_id = 0;
+    int32 prev_progress = 0;
+    if (it != active_actions.end()) {
+      LOG(DEBUG) << "Re-add action of " << user_id << " in " << dialog_id;
+      prev_action_id = it->action_id;
+      prev_progress = it->progress;
+      active_actions.erase(it);
+    } else {
+      LOG(DEBUG) << "Add action of " << user_id << " in " << dialog_id;
+    }
+
+    auto action_id = action->get_id();
+    auto progress = [&] {
+      switch (action_id) {
+        case td_api::chatActionUploadingVideo::ID:
+          return static_cast<td_api::chatActionUploadingVideo &>(*action).progress_;
+        case td_api::chatActionUploadingVoiceNote::ID:
+          return static_cast<td_api::chatActionUploadingVoiceNote &>(*action).progress_;
+        case td_api::chatActionUploadingPhoto::ID:
+          return static_cast<td_api::chatActionUploadingPhoto &>(*action).progress_;
+        case td_api::chatActionUploadingDocument::ID:
+          return static_cast<td_api::chatActionUploadingDocument &>(*action).progress_;
+        case td_api::chatActionUploadingVideoNote::ID:
+          return static_cast<td_api::chatActionUploadingVideoNote &>(*action).progress_;
+        default:
+          return 0;
+      }
+    }();
+    active_actions.emplace_back(user_id, action_id, Time::now());
+    if (action_id == prev_action_id && progress <= prev_progress) {
+      return;
+    }
+    if (active_actions.size() == 1u) {
+      LOG(DEBUG) << "Set action timeout in " << dialog_id;
+      active_dialog_action_timeout_.set_timeout_in(dialog_id.get(), DIALOG_ACTION_TIMEOUT);
+    }
+  }
+
+  LOG(DEBUG) << "Send action of " << user_id << " in " << dialog_id << ": " << to_string(action);
+  send_closure(G()->td(), &Td::send_update,
+               make_tl_object<td_api::updateUserChatAction>(
+                   dialog_id.get(), td_->contacts_manager_->get_user_id_object(user_id, "on_user_dialog_action"),
+                   std::move(action)));
+}
+
+void MessagesManager::cancel_user_dialog_action(DialogId dialog_id, const Message *m) {
+  CHECK(m != nullptr);
+  if (m->forward_info != nullptr || m->via_bot_user_id.is_valid() || m->is_channel_post) {
+    return;
+  }
+
+  on_user_dialog_action(dialog_id, m->sender_user_id, nullptr, m->content->get_id());
+}
+
+void MessagesManager::add_pending_channel_update(DialogId dialog_id, tl_object_ptr<telegram_api::Update> &&update,
+                                                 int32 new_pts, int32 pts_count, const char *source,
+                                                 bool is_postponed_udpate) {
+  LOG(INFO) << "Receive from " << source << " pending " << to_string(update);
+  CHECK(update != nullptr);
+  CHECK(dialog_id.get_type() == DialogType::Channel);
+  if (pts_count < 0 || new_pts <= pts_count) {
+    LOG(ERROR) << "Receive channel update from " << source << " with wrong pts = " << new_pts
+               << " or pts_count = " << pts_count << ": " << oneline(to_string(update));
+    return;
+  }
+
+  // TODO need to save all updates that can change result of running queries not associated with pts (for example
+  // getHistory) and apply them to result of this queries
+
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    auto pts = load_channel_pts(dialog_id);
+    if (pts > 0) {
+      auto channel_id = dialog_id.get_channel_id();
+      if (!td_->contacts_manager_->have_channel(channel_id)) {
+        // do not create dialog if there is no info about the channel
+        return;
+      }
+
+      d = add_dialog(dialog_id);
+      CHECK(d != nullptr);
+      CHECK(d->pts == pts);
+      update_dialog_pos(d, false, "add_pending_channel_update");
+    }
+  }
+  if (d == nullptr) {
+    // if there is no dialog, it can be created by the update
+    LOG(INFO) << "Receive pending update from " << source << " about unknown " << dialog_id;
+    if (running_get_channel_difference(dialog_id)) {
+      return;
+    }
+  } else {
+    int32 old_pts = d->pts;
+    if (new_pts <= old_pts) {  // very old or unuseful update
+      if (new_pts < old_pts - 19999 && !is_postponed_udpate) {
+        // restore channel pts after delete_first_messages
+        LOG(ERROR) << "Restore pts in " << d->dialog_id << " from " << source << " after delete_first_messages from "
+                   << old_pts << " to " << new_pts << " is temporarily disabled, pts_count = " << pts_count
+                   << ", update is from " << source << ": " << oneline(to_string(update));
+        if (old_pts < 10000000) {
+          dump_debug_message_op(d, 6);
+        }
+        get_channel_difference(dialog_id, old_pts, true, "add_pending_channel_update old");
+      }
+
+      if (update->get_id() == telegram_api::updateNewChannelMessage::ID) {
+        auto update_new_channel_message = static_cast<telegram_api::updateNewChannelMessage *>(update.get());
+        auto message_id = get_message_id(update_new_channel_message->message_);
+        FullMessageId full_message_id(dialog_id, message_id);
+        if (update_message_ids_.find(full_message_id) != update_message_ids_.end()) {
+          // apply sent channel message
+          on_get_message(std::move(update_new_channel_message->message_), true, true, true, true,
+                         "updateNewChannelMessage with an awaited message");
+          return;
+        }
+      }
+      if (update->get_id() == updateSentMessage::ID) {
+        auto update_sent_message = static_cast<updateSentMessage *>(update.get());
+        if (being_sent_messages_.count(update_sent_message->random_id_) > 0) {
+          // apply sent channel message
+          on_send_message_success(update_sent_message->random_id_, update_sent_message->message_id_,
+                                  update_sent_message->date_, FileId(), "process old updateSentChannelMessage");
+          return;
+        }
+      }
+
+      LOG_IF(WARNING, new_pts == old_pts && pts_count == 0)
+          << "Receive from " << source << " useless channel update " << oneline(to_string(update));
+      return;
+    }
+
+    if (running_get_channel_difference(dialog_id)) {
+      if (pts_count > 0) {
+        d->postponed_channel_updates.emplace(new_pts, PendingPtsUpdate(std::move(update), new_pts, pts_count));
+      }
+      return;
+    }
+
+    if (old_pts + pts_count != new_pts) {
+      LOG(WARNING) << "Found a gap in the " << dialog_id << " with pts = " << old_pts << ". new_pts = " << new_pts
+                   << ", pts_count = " << pts_count << " in update from " << source;
+
+      if (pts_count > 0) {
+        d->postponed_channel_updates.emplace(new_pts, PendingPtsUpdate(std::move(update), new_pts, pts_count));
+      }
+
+      get_channel_difference(dialog_id, old_pts, true, "add_pending_channel_update pts mismatch");
+      return;
+    }
+  }
+
+  if (d == nullptr || pts_count > 0) {
+    process_channel_update(std::move(update));
+    CHECK(!running_get_channel_difference(dialog_id)) << '"' << active_get_channel_differencies_[dialog_id] << '"';
+  } else {
+    LOG_IF(INFO, update->get_id() != dummyUpdate::ID)
+        << "Skip useless channel update from " << source << ": " << to_string(update);
+  }
+
+  if (d == nullptr) {
+    d = get_dialog(dialog_id);
+    if (d == nullptr) {
+      // dialog was not created by the update
+      return;
+    }
+  }
+
+  CHECK(new_pts > d->pts);
+  set_channel_pts(d, new_pts, source);
+}
+
+void MessagesManager::set_get_difference_timeout(double timeout) {
+  if (!pts_gap_timeout_.has_timeout()) {
+    LOG(INFO) << "Gap in pts has found, current pts is " << td_->updates_manager_->get_pts();
+    pts_gap_timeout_.set_callback(std::move(UpdatesManager::fill_pts_gap));
+    pts_gap_timeout_.set_callback_data(static_cast<void *>(td_));
+    pts_gap_timeout_.set_timeout_in(timeout);
+  }
+}
+
+void MessagesManager::process_update(tl_object_ptr<telegram_api::Update> &&update) {
+  switch (update->get_id()) {
+    case dummyUpdate::ID:
+      LOG(INFO) << "Process dummyUpdate";
+      break;
+    case telegram_api::updateNewMessage::ID:
+      LOG(INFO) << "Process updateNewMessage";
+      on_get_message(std::move(move_tl_object_as<telegram_api::updateNewMessage>(update)->message_), true, false, true,
+                     true, "updateNewMessage");
+      break;
+    case updateSentMessage::ID: {
+      auto send_message_success_update = move_tl_object_as<updateSentMessage>(update);
+      LOG(INFO) << "Process updateSentMessage " << send_message_success_update->random_id_;
+      on_send_message_success(send_message_success_update->random_id_, send_message_success_update->message_id_,
+                              send_message_success_update->date_, FileId(), "process updateSentMessage");
+      break;
+    }
+    case telegram_api::updateReadMessagesContents::ID: {
+      auto read_contents_update = move_tl_object_as<telegram_api::updateReadMessagesContents>(update);
+      LOG(INFO) << "Process updateReadMessageContents";
+      for (auto &message_id : read_contents_update->messages_) {
+        read_message_content_from_updates(MessageId(ServerMessageId(message_id)));
+      }
+      break;
+    }
+    case telegram_api::updateEditMessage::ID: {
+      auto full_message_id =
+          on_get_message(std::move(move_tl_object_as<telegram_api::updateEditMessage>(update)->message_), false, false,
+                         false, false, "updateEditMessage");
+      LOG(INFO) << "Process updateEditMessage";
+      if (full_message_id != FullMessageId() && td_->auth_manager_->is_bot()) {
+        send_update_message_edited(full_message_id);
+      }
+      break;
+    }
+    case telegram_api::updateDeleteMessages::ID: {
+      auto delete_update = move_tl_object_as<telegram_api::updateDeleteMessages>(update);
+      LOG(INFO) << "Process updateDeleteMessages";
+      vector<MessageId> message_ids;
+      for (auto &message : delete_update->messages_) {
+        message_ids.push_back(MessageId(ServerMessageId(message)));
+      }
+      delete_messages_from_updates(message_ids);
+      break;
+    }
+    case telegram_api::updateReadHistoryInbox::ID: {
+      auto read_update = move_tl_object_as<telegram_api::updateReadHistoryInbox>(update);
+      LOG(INFO) << "Process updateReadHistoryInbox";
+      read_history_inbox(DialogId(read_update->peer_), MessageId(ServerMessageId(read_update->max_id_)), -1,
+                         "updateReadHistoryInbox");
+      break;
+    }
+    case telegram_api::updateReadHistoryOutbox::ID: {
+      auto read_update = move_tl_object_as<telegram_api::updateReadHistoryOutbox>(update);
+      LOG(INFO) << "Process updateReadHistoryOutbox";
+      read_history_outbox(DialogId(read_update->peer_), MessageId(ServerMessageId(read_update->max_id_)));
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+  CHECK(!td_->updates_manager_->running_get_difference());
+}
+
+void MessagesManager::process_channel_update(tl_object_ptr<telegram_api::Update> &&update) {
+  switch (update->get_id()) {
+    case dummyUpdate::ID:
+      LOG(INFO) << "Process dummyUpdate";
+      break;
+    case updateSentMessage::ID: {
+      auto send_message_success_update = move_tl_object_as<updateSentMessage>(update);
+      LOG(INFO) << "Process updateSentMessage " << send_message_success_update->random_id_;
+      on_send_message_success(send_message_success_update->random_id_, send_message_success_update->message_id_,
+                              send_message_success_update->date_, FileId(), "process updateSentChannelMessage");
+      break;
+    }
+    case telegram_api::updateNewChannelMessage::ID:
+      LOG(INFO) << "Process updateNewChannelMessage";
+      on_get_message(std::move(move_tl_object_as<telegram_api::updateNewChannelMessage>(update)->message_), true, true,
+                     true, true, "updateNewChannelMessage");
+      break;
+    case telegram_api::updateDeleteChannelMessages::ID: {
+      auto delete_channel_messages_update = move_tl_object_as<telegram_api::updateDeleteChannelMessages>(update);
+      LOG(INFO) << "Process updateDeleteChannelMessages";
+      ChannelId channel_id(delete_channel_messages_update->channel_id_);
+      if (!channel_id.is_valid()) {
+        LOG(ERROR) << "Receive invalid " << channel_id;
+        break;
+      }
+
+      vector<MessageId> message_ids;
+      for (auto &message : delete_channel_messages_update->messages_) {
+        message_ids.push_back(MessageId(ServerMessageId(message)));
+      }
+
+      auto dialog_id = DialogId(channel_id);
+      delete_dialog_messages_from_updates(dialog_id, message_ids);
+      break;
+    }
+    case telegram_api::updateEditChannelMessage::ID: {
+      auto full_message_id =
+          on_get_message(std::move(move_tl_object_as<telegram_api::updateEditChannelMessage>(update)->message_), false,
+                         true, false, false, "updateEditChannelMessage");
+      LOG(INFO) << "Process updateEditChannelMessage";
+      if (full_message_id != FullMessageId() && td_->auth_manager_->is_bot()) {
+        send_update_message_edited(full_message_id);
+      }
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+}
+
+void MessagesManager::process_pending_updates() {
+  for (auto &update : pending_updates_) {
+    process_update(std::move(update.second.update));
+  }
+
+  td_->updates_manager_->set_pts(accumulated_pts_, "process pending updates")
+      .set_value(Unit());  // TODO can't set until get messages really stored on persistent storage
+  drop_pending_updates();
+}
+
+void MessagesManager::drop_pending_updates() {
+  accumulated_pts_count_ = 0;
+  accumulated_pts_ = -1;
+  pts_gap_timeout_.cancel_timeout();
+  pending_updates_.clear();
+}
+
+NotificationSettingsScope MessagesManager::get_notification_settings_scope(
+    tl_object_ptr<telegram_api::NotifyPeer> &&notify_peer_ptr) const {
+  switch (notify_peer_ptr->get_id()) {
+    case telegram_api::notifyPeer::ID: {
+      auto notify_peer = move_tl_object_as<telegram_api::notifyPeer>(notify_peer_ptr);
+      return DialogId(notify_peer->peer_).get();
+    }
+    case telegram_api::notifyUsers::ID:
+      return NOTIFICATION_SETTINGS_FOR_PRIVATE_CHATS;
+    case telegram_api::notifyChats::ID:
+      return NOTIFICATION_SETTINGS_FOR_GROUP_CHATS;
+    case telegram_api::notifyAll::ID:
+      return NOTIFICATION_SETTINGS_FOR_ALL_CHATS;
+    default:
+      UNREACHABLE();
+      return 0;
+  }
+}
+
+NotificationSettingsScope MessagesManager::get_notification_settings_scope(
+    const tl_object_ptr<td_api::NotificationSettingsScope> &scope) const {
+  if (scope == nullptr) {
+    return NOTIFICATION_SETTINGS_FOR_ALL_CHATS;
+  }
+  int32 scope_id = scope->get_id();
+  switch (scope_id) {
+    case td_api::notificationSettingsScopeChat::ID:
+      return static_cast<const td_api::notificationSettingsScopeChat *>(scope.get())->chat_id_;
+    case td_api::notificationSettingsScopePrivateChats::ID:
+      return NOTIFICATION_SETTINGS_FOR_PRIVATE_CHATS;
+    case td_api::notificationSettingsScopeBasicGroupChats::ID:
+      return NOTIFICATION_SETTINGS_FOR_GROUP_CHATS;
+    case td_api::notificationSettingsScopeAllChats::ID:
+      return NOTIFICATION_SETTINGS_FOR_ALL_CHATS;
+    default:
+      UNREACHABLE();
+      return 0;
+  }
+}
+
+string MessagesManager::get_notification_settings_scope_database_key(NotificationSettingsScope scope) {
+  switch (scope) {
+    case NOTIFICATION_SETTINGS_FOR_PRIVATE_CHATS:
+      return "nsfpc";
+    case NOTIFICATION_SETTINGS_FOR_GROUP_CHATS:
+      return "nsfgc";
+    case NOTIFICATION_SETTINGS_FOR_ALL_CHATS:
+      return "nsfac";
+    default:
+      UNREACHABLE();
+      return "";
+  }
+}
+
+bool MessagesManager::update_notification_settings(NotificationSettingsScope scope,
+                                                   NotificationSettings *current_settings,
+                                                   const NotificationSettings &new_settings) {
+  bool need_update = current_settings->mute_until != new_settings.mute_until ||
+                     current_settings->sound != new_settings.sound ||
+                     current_settings->show_preview != new_settings.show_preview ||
+                     current_settings->is_synchronized != new_settings.is_synchronized;
+  bool is_changed = need_update || current_settings->silent_send_message != new_settings.silent_send_message;
+
+  if (is_changed) {
+    if (scope != NOTIFICATION_SETTINGS_FOR_PRIVATE_CHATS && scope != NOTIFICATION_SETTINGS_FOR_GROUP_CHATS &&
+        scope != NOTIFICATION_SETTINGS_FOR_ALL_CHATS) {
+      DialogId dialog_id(scope);
+      CHECK(dialog_id.is_valid());
+      Dialog *d = get_dialog(dialog_id);
+      CHECK(d != nullptr) << "Wrong " << dialog_id << " in update_notification_settings";
+      update_dialog_unmute_timeout(d, current_settings->mute_until, new_settings.mute_until);
+      on_dialog_updated(dialog_id, "update_notification_settings");
+    } else {
+      string key = get_notification_settings_scope_database_key(scope);
+      G()->td_db()->get_binlog_pmc()->set(key, log_event_store(new_settings).as_slice().str());
+    }
+    LOG(INFO) << "Update notification settings in " << scope << " from " << *current_settings << " to " << new_settings;
+    *current_settings = new_settings;
+
+    if (need_update) {
+      send_closure(
+          G()->td(), &Td::send_update,
+          make_tl_object<td_api::updateNotificationSettings>(get_notification_settings_scope_object(scope),
+                                                             get_notification_settings_object(current_settings)));
+    }
+  }
+  return is_changed;
+}
+
+void MessagesManager::update_dialog_unmute_timeout(Dialog *d, int32 old_mute_until, int32 new_mute_until) {
+  if (old_mute_until == new_mute_until) {
+    return;
+  }
+  CHECK(d != nullptr);
+
+  auto now = G()->unix_time_cached();
+  if (new_mute_until >= now && new_mute_until < now + 366 * 86400) {
+    dialog_unmute_timeout_.set_timeout_in(d->dialog_id.get(), new_mute_until - now + 1);
+  } else {
+    dialog_unmute_timeout_.cancel_timeout(d->dialog_id.get());
+  }
+
+  if (old_mute_until != -1 && is_unread_count_inited_ && d->order != DEFAULT_ORDER) {
+    auto unread_count = d->server_unread_count + d->local_unread_count;
+    if (unread_count != 0) {
+      if (old_mute_until != 0 && new_mute_until == 0) {
+        unread_message_muted_count_ -= unread_count;
+        send_update_unread_message_count(d->dialog_id, true, "on_dialog_unmute");
+      }
+      if (old_mute_until == 0 && new_mute_until != 0) {
+        unread_message_muted_count_ += unread_count;
+        send_update_unread_message_count(d->dialog_id, true, "on_dialog_mute");
+      }
+    }
+  }
+}
+
+void MessagesManager::on_dialog_unmute(DialogId dialog_id) {
+  auto d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+
+  if (d->notification_settings.mute_until == 0) {
+    return;
+  }
+
+  auto now = G()->unix_time();
+  if (d->notification_settings.mute_until > now) {
+    LOG(ERROR) << "Failed to unmute " << dialog_id << " in " << now << ", will be unmuted in "
+               << d->notification_settings.mute_until;
+    update_dialog_unmute_timeout(d, -1, d->notification_settings.mute_until);
+    return;
+  }
+
+  LOG(INFO) << "Unmute " << dialog_id;
+  update_dialog_unmute_timeout(d, d->notification_settings.mute_until, 0);
+  d->notification_settings.mute_until = 0;
+  send_closure(G()->td(), &Td::send_update,
+               make_tl_object<td_api::updateNotificationSettings>(
+                   get_notification_settings_scope_object(NotificationSettingsScope(dialog_id.get())),
+                   get_notification_settings_object(&d->notification_settings)));
+  on_dialog_updated(dialog_id, "on_dialog_unmute");
+}
+
+void MessagesManager::on_update_notify_settings(
+    NotificationSettingsScope scope, tl_object_ptr<telegram_api::PeerNotifySettings> &&peer_notify_settings) {
+  const NotificationSettings notification_settings = get_notification_settings(std::move(peer_notify_settings));
+  if (!notification_settings.is_synchronized) {
+    return;
+  }
+
+  NotificationSettings *current_settings = get_notification_settings(scope, true);
+  if (current_settings == nullptr) {
+    return;
+  }
+  update_notification_settings(scope, current_settings, notification_settings);
+}
+
+bool MessagesManager::get_dialog_report_spam_state(DialogId dialog_id, Promise<Unit> &&promise) {
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    promise.set_error(Status::Error(3, "Chat not found"));
+    return false;
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    promise.set_error(Status::Error(3, "Can't access the chat"));
+    return false;
+  }
+
+  if (d->know_can_report_spam) {
+    promise.set_value(Unit());
+    return d->can_report_spam;
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+    case DialogType::Channel:
+      td_->create_handler<GetPeerSettingsQuery>(std::move(promise))->send(dialog_id);
+      return false;
+    case DialogType::SecretChat:
+      promise.set_value(Unit());
+      return false;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      return false;
+  }
+}
+
+void MessagesManager::change_dialog_report_spam_state(DialogId dialog_id, bool is_spam_dialog,
+                                                      Promise<Unit> &&promise) {
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return promise.set_error(Status::Error(3, "Chat not found"));
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    return promise.set_error(Status::Error(3, "Can't access the chat"));
+  }
+
+  if (!d->know_can_report_spam || !d->can_report_spam) {
+    return promise.set_error(Status::Error(3, "Can't update chat report spam state"));
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+    case DialogType::Channel:
+      return td_->create_handler<UpdatePeerSettingsQuery>(std::move(promise))->send(dialog_id, is_spam_dialog);
+    case DialogType::SecretChat:
+      if (is_spam_dialog) {
+        return td_->create_handler<ReportEncryptedSpamQuery>(std::move(promise))->send(dialog_id);
+      } else {
+        d->can_report_spam = false;
+        on_dialog_updated(dialog_id, "change_dialog_report_spam_state");
+        promise.set_value(Unit());
+        return;
+      }
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      return;
+  }
+}
+
+bool MessagesManager::can_report_dialog(DialogId dialog_id) const {
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      return td_->contacts_manager_->is_user_bot(dialog_id.get_user_id());
+    case DialogType::Chat:
+      return false;
+    case DialogType::Channel:
+      return !td_->contacts_manager_->get_channel_status(dialog_id.get_channel_id()).is_creator();
+    case DialogType::SecretChat:
+      return false;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      return false;
+  }
+}
+
+void MessagesManager::report_dialog(DialogId dialog_id, const tl_object_ptr<td_api::ChatReportReason> &reason,
+                                    const vector<MessageId> &message_ids, Promise<Unit> &&promise) {
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return promise.set_error(Status::Error(3, "Chat not found"));
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    return promise.set_error(Status::Error(3, "Can't access the chat"));
+  }
+
+  if (reason == nullptr) {
+    return promise.set_error(Status::Error(3, "Reason shouldn't be empty"));
+  }
+
+  if (!can_report_dialog(dialog_id)) {
+    return promise.set_error(Status::Error(3, "Chat can't be reported"));
+  }
+
+  vector<MessageId> server_message_ids;
+  for (auto message_id : message_ids) {
+    if (message_id.is_valid() && message_id.is_server()) {
+      server_message_ids.push_back(message_id);
+    }
+  }
+
+  tl_object_ptr<telegram_api::ReportReason> report_reason;
+  switch (reason->get_id()) {
+    case td_api::chatReportReasonSpam::ID:
+      report_reason = make_tl_object<telegram_api::inputReportReasonSpam>();
+      break;
+    case td_api::chatReportReasonViolence::ID:
+      report_reason = make_tl_object<telegram_api::inputReportReasonViolence>();
+      break;
+    case td_api::chatReportReasonPornography::ID:
+      report_reason = make_tl_object<telegram_api::inputReportReasonPornography>();
+      break;
+    case td_api::chatReportReasonCustom::ID: {
+      auto other_reason = static_cast<const td_api::chatReportReasonCustom *>(reason.get());
+      auto text = other_reason->text_;
+      if (!clean_input_string(text)) {
+        return promise.set_error(Status::Error(400, "Text must be encoded in UTF-8"));
+      }
+
+      report_reason = make_tl_object<telegram_api::inputReportReasonOther>(text);
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+  CHECK(report_reason != nullptr);
+
+  td_->create_handler<ReportPeerQuery>(std::move(promise))
+      ->send(dialog_id, std::move(report_reason), server_message_ids);
+}
+
+void MessagesManager::on_get_peer_settings(DialogId dialog_id,
+                                           tl_object_ptr<telegram_api::peerSettings> &&peer_settings) {
+  CHECK(peer_settings != nullptr);
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return;
+  }
+
+  d->know_can_report_spam = true;
+  d->can_report_spam = (peer_settings->flags_ & telegram_api::peerSettings::REPORT_SPAM_MASK) != 0;
+  on_dialog_updated(dialog_id, "can_report_spam");
+}
+
+void MessagesManager::load_secret_thumbnail(FileId thumbnail_file_id) {
+  class Callback : public FileManager::DownloadCallback {
+   public:
+    explicit Callback(Promise<> download_promise) : download_promise_(std::move(download_promise)) {
+    }
+
+    void on_download_ok(FileId file_id) override {
+      download_promise_.set_value(Unit());
+    }
+    void on_download_error(FileId file_id, Status error) override {
+      download_promise_.set_error(std::move(error));
+    }
+
+   private:
+    Promise<> download_promise_;
+  };
+
+  auto thumbnail_promise = PromiseCreator::lambda([actor_id = actor_id(this),
+                                                   thumbnail_file_id](Result<BufferSlice> r_thumbnail) mutable {
+    BufferSlice thumbnail_slice;
+    if (r_thumbnail.is_ok()) {
+      thumbnail_slice = r_thumbnail.move_as_ok();
+    }
+    send_closure(actor_id, &MessagesManager::on_load_secret_thumbnail, thumbnail_file_id, std::move(thumbnail_slice));
+  });
+
+  auto download_promise = PromiseCreator::lambda(
+      [thumbnail_file_id, thumbnail_promise = std::move(thumbnail_promise)](Result<Unit> r_download) mutable {
+        if (r_download.is_error()) {
+          thumbnail_promise.set_error(r_download.move_as_error());
+          return;
+        }
+        send_closure(G()->file_manager(), &FileManager::get_content, thumbnail_file_id, std::move(thumbnail_promise));
+      });
+
+  send_closure(G()->file_manager(), &FileManager::download, thumbnail_file_id,
+               std::make_unique<Callback>(std::move(download_promise)), 1);
+}
+
+void MessagesManager::on_upload_media(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file,
+                                      tl_object_ptr<telegram_api::InputEncryptedFile> input_encrypted_file) {
+  LOG(INFO) << "File " << file_id << " has been uploaded";
+
+  auto it = being_uploaded_files_.find(file_id);
+  if (it == being_uploaded_files_.end()) {
+    // callback may be called just before the file upload was cancelled
+    return;
+  }
+
+  auto full_message_id = it->second.first;
+  auto thumbnail_file_id = it->second.second;
+
+  being_uploaded_files_.erase(it);
+
+  Message *m = get_message(full_message_id);
+  if (m == nullptr) {
+    // message has already been deleted by the user or sent to inaccessible channel, do not need to send it
+    // file upload should be already cancelled in cancel_send_message_query, it shouldn't happen
+    LOG(ERROR) << "Message with a media has already been deleted";
+    return;
+  }
+
+  auto dialog_id = full_message_id.get_dialog_id();
+  auto can_send_status = can_send_message(dialog_id);
+  if (can_send_status.is_error()) {
+    // user has left the chat during upload of the file or lost his privileges
+    LOG(INFO) << "Can't send a message to " << dialog_id << ": " << can_send_status.error();
+
+    int64 random_id = begin_send_message(dialog_id, m);
+    on_send_message_fail(random_id, can_send_status.move_as_error());
+    return;
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+    case DialogType::Channel:
+      if (input_file && thumbnail_file_id.is_valid()) {
+        // TODO: download thumbnail if needed (like in secret chats)
+        being_uploaded_thumbnails_[thumbnail_file_id] = {full_message_id, file_id, std::move(input_file)};
+        LOG(INFO) << "Ask to upload thumbnail " << thumbnail_file_id;
+        td_->file_manager_->upload(thumbnail_file_id, upload_thumbnail_callback_, 1, m->message_id.get());
+      } else {
+        do_send_media(dialog_id, m, file_id, thumbnail_file_id, std::move(input_file), nullptr);
+      }
+      break;
+    case DialogType::SecretChat:
+      if (thumbnail_file_id.is_valid()) {
+        being_loaded_secret_thumbnails_[thumbnail_file_id] = {full_message_id, file_id,
+                                                              std::move(input_encrypted_file)};
+        LOG(INFO) << "Ask to load thumbnail " << thumbnail_file_id;
+
+        load_secret_thumbnail(thumbnail_file_id);
+      } else {
+        do_send_secret_media(dialog_id, m, file_id, thumbnail_file_id, std::move(input_encrypted_file), BufferSlice());
+      }
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      break;
+  }
+}
+
+void MessagesManager::do_send_media(DialogId dialog_id, Message *m, FileId file_id, FileId thumbnail_file_id,
+                                    tl_object_ptr<telegram_api::InputFile> input_file,
+                                    tl_object_ptr<telegram_api::InputFile> input_thumbnail) {
+  if (input_file == nullptr) {
+    CHECK(input_thumbnail == nullptr);
+    file_id = FileId();
+    thumbnail_file_id = FileId();
+  }
+  CHECK(m != nullptr);
+  on_message_media_uploaded(
+      dialog_id, m, get_input_media(m->content.get(), std::move(input_file), std::move(input_thumbnail), m->ttl),
+      file_id, thumbnail_file_id);
+}
+
+void MessagesManager::do_send_secret_media(DialogId dialog_id, Message *m, FileId file_id, FileId thumbnail_file_id,
+                                           tl_object_ptr<telegram_api::InputEncryptedFile> input_encrypted_file,
+                                           BufferSlice thumbnail) {
+  if (input_encrypted_file == nullptr) {
+    file_id = FileId();
+    thumbnail_file_id = FileId();
+  }
+
+  CHECK(dialog_id.get_type() == DialogType::SecretChat);
+  CHECK(m != nullptr);
+  auto layer = td_->contacts_manager_->get_secret_chat_layer(dialog_id.get_secret_chat_id());
+  on_secret_message_media_uploaded(
+      dialog_id, m,
+      get_secret_input_media(m->content.get(), std::move(input_encrypted_file), std::move(thumbnail), layer), file_id,
+      thumbnail_file_id);
+}
+
+void MessagesManager::on_upload_media_error(FileId file_id, Status status) {
+  if (G()->close_flag()) {
+    // do not fail upload if closing
+    return;
+  }
+
+  LOG(WARNING) << "File " << file_id << " has upload error " << status;
+  CHECK(status.is_error());
+
+  auto it = being_uploaded_files_.find(file_id);
+  if (it == being_uploaded_files_.end()) {
+    // callback may be called just before the file upload was cancelled
+    return;
+  }
+
+  auto full_message_id = it->second.first;
+
+  being_uploaded_files_.erase(it);
+
+  fail_send_message(full_message_id, status.code() > 0 ? status.code() : 500,
+                    status.message().str());  // TODO CHECK that status has always a code
+}
+
+void MessagesManager::on_load_secret_thumbnail(FileId thumbnail_file_id, BufferSlice thumbnail) {
+  if (G()->close_flag()) {
+    // do not send secret media if closing, thumbnail may be wrong
+    return;
+  }
+
+  LOG(INFO) << "SecretThumbnail " << thumbnail_file_id << " has been loaded with size " << thumbnail.size();
+
+  auto it = being_loaded_secret_thumbnails_.find(thumbnail_file_id);
+  if (it == being_loaded_secret_thumbnails_.end()) {
+    // just in case, as in on_upload_thumbnail
+    return;
+  }
+
+  auto full_message_id = it->second.full_message_id;
+  auto file_id = it->second.file_id;
+  auto input_file = std::move(it->second.input_file);
+
+  being_loaded_secret_thumbnails_.erase(it);
+
+  Message *m = get_message(full_message_id);
+  if (m == nullptr) {
+    // message has already been deleted by the user, do not need to send it
+    // cancel file upload of the main file to allow next upload with the same file to succeed
+    td_->file_manager_->upload(file_id, nullptr, 0, 0);
+    LOG(INFO) << "Message with a media has already been deleted";
+    return;
+  }
+
+  if (thumbnail.empty()) {
+    delete_message_content_thumbnail(m->content.get());
+  }
+
+  auto dialog_id = full_message_id.get_dialog_id();
+  auto can_send_status = can_send_message(dialog_id);
+  if (can_send_status.is_error()) {
+    // secret chat was closed during load of the file
+    LOG(INFO) << "Can't send a message to " << dialog_id << ": " << can_send_status.error();
+
+    int64 random_id = begin_send_message(dialog_id, m);
+    on_send_message_fail(random_id, can_send_status.move_as_error());
+    return;
+  }
+
+  do_send_secret_media(dialog_id, m, file_id, thumbnail_file_id, std::move(input_file), std::move(thumbnail));
+}
+
+void MessagesManager::on_upload_thumbnail(FileId thumbnail_file_id,
+                                          tl_object_ptr<telegram_api::InputFile> thumbnail_input_file) {
+  if (G()->close_flag()) {
+    // do not fail upload if closing
+    return;
+  }
+
+  LOG(INFO) << "Thumbnail " << thumbnail_file_id << " has been uploaded as " << to_string(thumbnail_input_file);
+
+  auto it = being_uploaded_thumbnails_.find(thumbnail_file_id);
+  if (it == being_uploaded_thumbnails_.end()) {
+    // callback may be called just before the thumbnail upload was cancelled
+    return;
+  }
+
+  auto full_message_id = it->second.full_message_id;
+  auto file_id = it->second.file_id;
+  auto input_file = std::move(it->second.input_file);
+
+  being_uploaded_thumbnails_.erase(it);
+
+  Message *m = get_message(full_message_id);
+  if (m == nullptr) {
+    // message has already been deleted by the user or sent to inaccessible channel, do not need to send it
+    // thumbnail file upload should be already cancelled in cancel_send_message_query
+    LOG(ERROR) << "Message with a media has already been deleted";
+    return;
+  }
+
+  if (thumbnail_input_file == nullptr) {
+    delete_message_content_thumbnail(m->content.get());
+  }
+
+  auto dialog_id = full_message_id.get_dialog_id();
+  auto can_send_status = can_send_message(dialog_id);
+  if (can_send_status.is_error()) {
+    // user has left the chat during upload of the thumbnail or lost his privileges
+    LOG(INFO) << "Can't send a message to " << dialog_id << ": " << can_send_status.error();
+
+    int64 random_id = begin_send_message(dialog_id, m);
+    on_send_message_fail(random_id, can_send_status.move_as_error());
+    return;
+  }
+
+  do_send_media(dialog_id, m, file_id, thumbnail_file_id, std::move(input_file), std::move(thumbnail_input_file));
+}
+
+void MessagesManager::on_upload_dialog_photo(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) {
+  LOG(INFO) << "File " << file_id << " has been uploaded";
+
+  auto it = uploaded_dialog_photos_.find(file_id);
+  if (it == uploaded_dialog_photos_.end()) {
+    // just in case, as in on_upload_media
+    return;
+  }
+
+  Promise<Unit> promise = std::move(it->second.promise);
+  DialogId dialog_id = it->second.dialog_id;
+
+  uploaded_dialog_photos_.erase(it);
+
+  tl_object_ptr<telegram_api::InputChatPhoto> input_chat_photo;
+  FileView file_view = td_->file_manager_->get_file_view(file_id);
+  CHECK(!file_view.is_encrypted());
+  if (file_view.has_remote_location()) {
+    if (file_view.remote_location().is_web()) {
+      // TODO reupload
+      promise.set_error(Status::Error(400, "Can't use web photo as profile photo"));
+      return;
+    }
+    input_chat_photo = make_tl_object<telegram_api::inputChatPhoto>(file_view.remote_location().as_input_photo());
+    file_id = FileId();
+  } else {
+    CHECK(input_file != nullptr);
+    input_chat_photo = make_tl_object<telegram_api::inputChatUploadedPhoto>(std::move(input_file));
+  }
+
+  // TODO invoke after
+  td_->create_handler<EditDialogPhotoQuery>(std::move(promise))->send(file_id, dialog_id, std::move(input_chat_photo));
+}
+
+void MessagesManager::on_upload_dialog_photo_error(FileId file_id, Status status) {
+  if (G()->close_flag()) {
+    // do not fail upload if closing
+    return;
+  }
+
+  LOG(INFO) << "File " << file_id << " has upload error " << status;
+  CHECK(status.is_error());
+
+  auto it = uploaded_dialog_photos_.find(file_id);
+  if (it == uploaded_dialog_photos_.end()) {
+    // just in case, as in on_upload_media_error
+    return;
+  }
+
+  Promise<Unit> promise = std::move(it->second.promise);
+
+  uploaded_dialog_photos_.erase(it);
+
+  promise.set_error(std::move(status));
+}
+
+void MessagesManager::before_get_difference() {
+  running_get_difference_ = true;
+
+  postponed_pts_updates_.insert(std::make_move_iterator(pending_updates_.begin()),
+                                std::make_move_iterator(pending_updates_.end()));
+
+  drop_pending_updates();
+}
+
+void MessagesManager::after_get_difference() {
+  CHECK(!td_->updates_manager_->running_get_difference());
+
+  if (postponed_pts_updates_.size()) {
+    LOG(INFO) << "Begin to apply postponed pts updates";
+    auto old_pts = td_->updates_manager_->get_pts();
+    for (auto &update : postponed_pts_updates_) {
+      auto new_pts = update.second.pts;
+      if (new_pts <= old_pts) {
+        skip_old_pending_update(std::move(update.second.update), new_pts, old_pts, update.second.pts_count,
+                                "after get difference");
+      } else {
+        add_pending_update(std::move(update.second.update), update.second.pts, update.second.pts_count, false,
+                           "after get difference");
+      }
+      CHECK(!td_->updates_manager_->running_get_difference());
+    }
+    postponed_pts_updates_.clear();
+    LOG(INFO) << "Finish to apply postponed pts updates";
+  }
+
+  running_get_difference_ = false;
+
+  if (!pending_on_get_dialogs_.empty()) {
+    LOG(INFO) << "Apply postponed results of getDialogs";
+    for (auto &res : pending_on_get_dialogs_) {
+      on_get_dialogs(std::move(res.dialogs), res.total_count, std::move(res.messages), std::move(res.promise));
+    }
+    pending_on_get_dialogs_.clear();
+  }
+
+  if (!postponed_chat_read_inbox_updates_.empty()) {
+    LOG(INFO) << "Send postponed chat read inbox updates";
+    auto dialog_ids = std::move(postponed_chat_read_inbox_updates_);
+    for (auto dialog_id : dialog_ids) {
+      send_update_chat_read_inbox(get_dialog(dialog_id), false, "after_get_difference");
+    }
+  }
+  if (have_postponed_unread_message_count_update_) {
+    LOG(INFO) << "Send postponed unread message count update";
+    send_update_unread_message_count(DialogId(), false, "after_get_difference");
+  }
+
+  for (auto &it : update_message_ids_) {
+    // this is impossible for ordinary chats because updates coming during getDifference have already been applied
+    auto dialog_id = it.first.get_dialog_id();
+    switch (dialog_id.get_type()) {
+      case DialogType::Channel:
+        // get channel difference may prevent updates from being applied
+        if (running_get_channel_difference(dialog_id)) {
+          break;
+        }
+      // fallthrough
+      case DialogType::User:
+      case DialogType::Chat:
+        LOG(ERROR) << "Receive updateMessageId from " << it.second << " to " << it.first
+                   << " but not receive corresponding message. " << td_->updates_manager_->get_state();
+        if (dialog_id.get_type() != DialogType::Channel) {
+          dump_debug_message_op(get_dialog(dialog_id));
+        }
+        break;
+      case DialogType::SecretChat:
+        break;
+      case DialogType::None:
+      default:
+        UNREACHABLE();
+        break;
+    }
+  }
+
+  if (td_->is_online()) {
+    // TODO move to AnimationsManager
+    td_->animations_manager_->get_saved_animations(Auto());
+
+    // TODO move to StickersManager
+    td_->stickers_manager_->get_installed_sticker_sets(false, Auto());
+    td_->stickers_manager_->get_installed_sticker_sets(true, Auto());
+    td_->stickers_manager_->get_featured_sticker_sets(Auto());
+    td_->stickers_manager_->get_recent_stickers(false, Auto());
+    td_->stickers_manager_->get_recent_stickers(true, Auto());
+    td_->stickers_manager_->get_favorite_stickers(Auto());
+  }
+
+  load_notification_settings();
+
+  // TODO move to ContactsManager or delete after users will become persistent
+  td_->contacts_manager_->get_user(td_->contacts_manager_->get_my_id("after_get_difference"), false, Promise<Unit>());
+
+  // TODO resend some messages
+}
+
+void MessagesManager::on_get_messages(vector<tl_object_ptr<telegram_api::Message>> &&messages, bool is_channel_message,
+                                      const char *source) {
+  LOG(DEBUG) << "Receive " << messages.size() << " messages";
+  for (auto &message : messages) {
+    on_get_message(std::move(message), false, is_channel_message, false, false, source);
+  }
+}
+
+void MessagesManager::on_get_history(DialogId dialog_id, MessageId from_message_id, int32 offset, int32 limit,
+                                     bool from_the_end, vector<tl_object_ptr<telegram_api::Message>> &&messages) {
+  LOG(INFO) << "Receive " << messages.size() << " history messages " << (from_the_end ? "from the end " : "") << "in "
+            << dialog_id << " from " << from_message_id << " with offset " << offset << " and limit " << limit;
+  CHECK(-limit < offset && offset <= 0);
+  CHECK(offset < 0 || from_the_end);
+
+  if (narrow_cast<int32>(messages.size()) < limit + offset && !messages.empty()) {
+    MessageId first_received_message_id = get_message_id(messages.back());
+    if (first_received_message_id.get() >= from_message_id.get()) {
+      // it is likely that there is no more history messages on the server
+      Dialog *d = get_dialog(dialog_id);
+      if (d != nullptr && d->first_database_message_id.is_valid() &&
+          d->first_database_message_id.get() <= first_received_message_id.get()) {
+        d->have_full_history = true;
+        on_dialog_updated(dialog_id, "set have_full_history");
+      }
+    }
+  }
+
+  if (from_the_end && narrow_cast<int32>(messages.size()) < limit) {
+    // it is likely that there is no more history messages on the server
+    Dialog *d = get_dialog(dialog_id);
+    if (d != nullptr) {
+      d->have_full_history = true;
+      on_dialog_updated(dialog_id, "set have_full_history");
+    }
+  }
+
+  if (messages.empty()) {
+    if (from_the_end) {
+      Dialog *d = get_dialog(dialog_id);
+      if (d != nullptr && d->have_full_history) {
+        set_dialog_is_empty(d, "on_get_history empty");
+      }
+    }
+
+    // be aware that in some cases an empty answer may be returned, because of the race of getHistory and deleteMessages
+    // and not because there is no more messages
+    return;
+  }
+
+  // TODO check that messages are received in decreasing message_id order
+
+  // be aware that dialog may not yet exist
+  // be aware that returned messages are guaranteed to be consecutive messages, but if !from_the_end they
+  // may be older (if some messages was deleted) or newer (if some messages were added) than an expected answer
+  // be aware that any subset of the returned messages may be already deleted and returned as MessageEmpty
+  bool is_channel_message = dialog_id.get_type() == DialogType::Channel;
+  MessageId first_added_message_id;
+  MessageId last_received_message_id = get_message_id(messages[0]);
+  MessageId last_added_message_id;
+  bool have_next = false;
+  Dialog *d = get_dialog(dialog_id);
+
+  MessageId prev_last_new_message_id;
+  MessageId prev_first_database_message_id;
+  MessageId prev_last_database_message_id;
+  MessageId prev_last_message_id;
+  if (d != nullptr) {
+    prev_last_new_message_id = d->last_new_message_id;
+    prev_first_database_message_id = d->first_database_message_id;
+    prev_last_database_message_id = d->last_database_message_id;
+    prev_last_message_id = d->last_message_id;
+  }
+
+  for (auto &message : messages) {
+    if (!have_next && from_the_end && get_message_id(message).get() < d->last_message_id.get()) {
+      // last message in the dialog should be attached to the next message if there is some
+      have_next = true;
+    }
+
+    auto message_dialog_id = get_message_dialog_id(message);
+    if (message_dialog_id != dialog_id) {
+      LOG(ERROR) << "Receive " << get_message_id(message) << " in wrong " << message_dialog_id << " instead of "
+                 << dialog_id << ": " << oneline(to_string(message));
+      continue;
+    }
+
+    auto full_message_id =
+        on_get_message(std::move(message), false, is_channel_message, false, have_next, "get history");
+    auto message_id = full_message_id.get_message_id();
+    if (message_id.is_valid()) {
+      if (!last_added_message_id.is_valid()) {
+        last_added_message_id = message_id;
+      }
+
+      if (!have_next) {
+        if (d == nullptr) {
+          d = get_dialog(dialog_id);
+          CHECK(d != nullptr);
+        }
+        have_next = true;
+      } else if (first_added_message_id.is_valid()) {
+        Message *next_message = get_message(d, first_added_message_id);
+        CHECK(next_message != nullptr);
+        if (!next_message->have_previous) {
+          LOG(INFO) << "Fix have_previous for " << first_added_message_id;
+          next_message->have_previous = true;
+          attach_message_to_previous(d, first_added_message_id);
+        }
+      }
+      first_added_message_id = message_id;
+      if (!message_id.is_yet_unsent()) {
+        // message should be already saved to database in on_get_message
+        // add_message_to_database(d, get_message(d, message_id), "on_get_history");
+      }
+    }
+  }
+
+  if (d == nullptr) {
+    return;
+  }
+
+  //  LOG_IF(ERROR, d->first_message_id.is_valid() && d->first_message_id.get() > first_received_message_id.get())
+  //      << "Receive message " << first_received_message_id << ", but first chat message is " << d->first_message_id;
+
+  bool need_update_database_message_ids =
+      last_added_message_id.is_valid() &&
+      (from_the_end || (last_added_message_id.get() >= d->first_database_message_id.get() &&
+                        d->last_database_message_id.get() >= first_added_message_id.get()));
+  if (from_the_end) {
+    if (!d->last_new_message_id.is_valid()) {
+      set_dialog_last_new_message_id(
+          d, last_added_message_id.is_valid() ? last_added_message_id : last_received_message_id, "on_get_history");
+    }
+    if (last_added_message_id.is_valid()) {
+      if (last_added_message_id.get() > d->last_message_id.get()) {
+        CHECK(d->last_new_message_id.is_valid());
+        set_dialog_last_message_id(d, last_added_message_id, "on_get_history");
+        send_update_chat_last_message(d, "on_get_history");
+      }
+    }
+  }
+
+  if (need_update_database_message_ids) {
+    bool is_dialog_updated = false;
+    if (!d->last_database_message_id.is_valid()) {
+      CHECK(d->last_message_id.is_valid());
+      MessagesConstIterator it(d, d->last_message_id);
+      while (*it != nullptr) {
+        auto message_id = (*it)->message_id;
+        if (message_id.is_server() || message_id.is_local()) {
+          if (!d->last_database_message_id.is_valid()) {
+            set_dialog_last_database_message_id(d, message_id, "on_get_history");
+          }
+          set_dialog_first_database_message_id(d, message_id, "on_get_history");
+          try_restore_dialog_reply_markup(d, *it);
+        }
+        --it;
+      }
+      is_dialog_updated = true;
+    } else {
+      CHECK(d->last_new_message_id.is_valid())
+          << dialog_id << " " << from_the_end << " " << d->first_database_message_id << " "
+          << d->last_database_message_id << " " << first_added_message_id << " " << last_added_message_id << " "
+          << d->last_message_id << prev_last_new_message_id << prev_first_database_message_id
+          << prev_last_database_message_id << prev_last_message_id;
+      CHECK(d->first_database_message_id.is_valid());
+      {
+        MessagesConstIterator it(d, d->first_database_message_id);
+        if (*it != nullptr && ((*it)->message_id == d->first_database_message_id || (*it)->have_next)) {
+          while (*it != nullptr) {
+            auto message_id = (*it)->message_id;
+            if ((message_id.is_server() || message_id.is_local()) &&
+                message_id.get() < d->first_database_message_id.get()) {
+              set_dialog_first_database_message_id(d, message_id, "on_get_history 2");
+              try_restore_dialog_reply_markup(d, *it);
+              is_dialog_updated = true;
+            }
+            --it;
+          }
+        }
+      }
+      {
+        MessagesConstIterator it(d, d->last_database_message_id);
+        if (*it != nullptr && ((*it)->message_id == d->last_database_message_id || (*it)->have_next)) {
+          while (*it != nullptr) {
+            auto message_id = (*it)->message_id;
+            if ((message_id.is_server() || message_id.is_local()) &&
+                message_id.get() > d->last_database_message_id.get()) {
+              set_dialog_last_database_message_id(d, message_id, "on_get_history 2");
+              is_dialog_updated = true;
+            }
+            ++it;
+          }
+        }
+      }
+    }
+    CHECK(d->first_database_message_id.is_valid());
+    CHECK(d->last_database_message_id.is_valid());
+
+    for (auto &first_message_id : d->first_database_message_id_by_index) {
+      if (first_added_message_id.get() < first_message_id.get() &&
+          first_message_id.get() <= last_added_message_id.get()) {
+        first_message_id = first_added_message_id;
+      }
+    }
+
+    if (is_dialog_updated) {
+      on_dialog_updated(dialog_id, "on_get_history");
+    }
+  }
+}
+
+vector<DialogId> MessagesManager::get_peers_dialog_ids(vector<tl_object_ptr<telegram_api::Peer>> &&peers) {
+  vector<DialogId> result;
+  result.reserve(peers.size());
+  for (auto &peer : peers) {
+    DialogId dialog_id(peer);
+    if (dialog_id.is_valid()) {
+      force_create_dialog(dialog_id, "get_peers_dialog_ids");
+      result.push_back(dialog_id);
+    }
+  }
+  return result;
+}
+
+void MessagesManager::on_get_public_dialogs_search_result(const string &query,
+                                                          vector<tl_object_ptr<telegram_api::Peer>> &&my_peers,
+                                                          vector<tl_object_ptr<telegram_api::Peer>> &&peers) {
+  auto it = search_public_dialogs_queries_.find(query);
+  CHECK(it != search_public_dialogs_queries_.end());
+  CHECK(it->second.size() > 0);
+  auto promises = std::move(it->second);
+  search_public_dialogs_queries_.erase(it);
+
+  found_public_dialogs_[query] = get_peers_dialog_ids(std::move(peers));
+  found_on_server_dialogs_[query] = get_peers_dialog_ids(std::move(my_peers));
+
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+void MessagesManager::on_failed_public_dialogs_search(const string &query, Status &&error) {
+  auto it = search_public_dialogs_queries_.find(query);
+  CHECK(it != search_public_dialogs_queries_.end());
+  CHECK(it->second.size() > 0);
+  auto promises = std::move(it->second);
+  search_public_dialogs_queries_.erase(it);
+
+  found_public_dialogs_[query];     // negative cache
+  found_on_server_dialogs_[query];  // negative cache
+
+  for (auto &promise : promises) {
+    promise.set_error(error.clone());
+  }
+}
+
+void MessagesManager::on_get_dialog_messages_search_result(DialogId dialog_id, const string &query,
+                                                           UserId sender_user_id, MessageId from_message_id,
+                                                           int32 offset, int32 limit, SearchMessagesFilter filter,
+                                                           int64 random_id, int32 total_count,
+                                                           vector<tl_object_ptr<telegram_api::Message>> &&messages) {
+  LOG(INFO) << "Receive " << messages.size() << " found messages in " << dialog_id;
+  if (!dialog_id.is_valid()) {
+    CHECK(query.empty());
+    CHECK(!sender_user_id.is_valid());
+    auto it = found_call_messages_.find(random_id);
+    CHECK(it != found_call_messages_.end());
+
+    MessageId first_added_message_id;
+    if (messages.empty()) {
+      // messages may be empty because there is no more messages or they can't be found due to global limit
+      // anyway pretend that there is no more messages
+      first_added_message_id = MessageId::min();
+    }
+
+    auto &result = it->second.second;
+    CHECK(result.empty());
+    for (auto &message : messages) {
+      auto new_message = on_get_message(std::move(message), false, false, false, false, "search call messages");
+      if (new_message != FullMessageId()) {
+        result.push_back(new_message);
+      }
+
+      auto message_id = new_message.get_message_id();
+      if (message_id.get() < first_added_message_id.get() || !first_added_message_id.is_valid()) {
+        first_added_message_id = message_id;
+      }
+    }
+    if (G()->parameters().use_message_db) {
+      bool update_state = false;
+
+      auto &old_message_count = calls_db_state_.message_count_by_index[search_calls_filter_index(filter)];
+      if (old_message_count != total_count) {
+        LOG(INFO) << "Update calls database message count to " << total_count;
+        old_message_count = total_count;
+        update_state = true;
+      }
+
+      auto &old_first_db_message_id =
+          calls_db_state_.first_calls_database_message_id_by_index[search_calls_filter_index(filter)];
+      bool from_the_end = !from_message_id.is_valid() || from_message_id.get() >= MessageId::max().get();
+      LOG(INFO) << "from_the_end = " << from_the_end << ", old_first_db_message_id = " << old_first_db_message_id.get()
+                << ", first_added_message_id = " << first_added_message_id.get()
+                << ", from_message_id = " << from_message_id.get();
+      if ((from_the_end ||
+           (old_first_db_message_id.is_valid() && old_first_db_message_id.get() <= from_message_id.get())) &&
+          (!old_first_db_message_id.is_valid() || first_added_message_id.get() < old_first_db_message_id.get())) {
+        LOG(INFO) << "Update calls database first message id to " << first_added_message_id;
+        old_first_db_message_id = first_added_message_id;
+        update_state = true;
+      }
+      if (update_state) {
+        save_calls_db_state();
+      }
+    }
+    it->second.first = total_count;
+    return;
+  }
+
+  auto it = found_dialog_messages_.find(random_id);
+  CHECK(it != found_dialog_messages_.end());
+
+  auto &result = it->second.second;
+  CHECK(result.empty());
+  MessageId first_added_message_id;
+  if (messages.empty()) {
+    // messages may be empty because there is no more messages or they can't be found due to global limit
+    // anyway pretend that there is no more messages
+    first_added_message_id = MessageId::min();
+  }
+  for (auto &message : messages) {
+    auto new_message = on_get_message(std::move(message), false, dialog_id.get_type() == DialogType::Channel, false,
+                                      false, "search chat messages");
+    if (new_message != FullMessageId()) {
+      if (new_message.get_dialog_id() != dialog_id) {
+        LOG(ERROR) << "Receive " << new_message << " instead of a message in " << dialog_id;
+        continue;
+      }
+
+      // TODO check that messages are returned in decreasing message_id order
+      auto message_id = new_message.get_message_id();
+      if (message_id.get() < first_added_message_id.get() || !first_added_message_id.is_valid()) {
+        first_added_message_id = message_id;
+      }
+      result.push_back(message_id);
+    } else {
+      total_count--;
+    }
+  }
+  if (total_count < static_cast<int32>(result.size())) {
+    LOG(ERROR) << "Receive " << result.size() << " valid messages out of " << total_count << " in " << messages.size()
+               << " messages";
+    total_count = static_cast<int32>(result.size());
+  }
+  if (query.empty() && !sender_user_id.is_valid() && filter != SearchMessagesFilter::Empty &&
+      G()->parameters().use_message_db) {
+    Dialog *d = get_dialog(dialog_id);
+    CHECK(d != nullptr);
+    bool update_dialog = false;
+
+    auto &old_message_count = d->message_count_by_index[search_messages_filter_index(filter)];
+    if (old_message_count != total_count) {
+      old_message_count = total_count;
+      if (filter == SearchMessagesFilter::UnreadMention) {
+        d->unread_mention_count = old_message_count;
+        send_update_chat_unread_mention_count(d);
+      }
+      update_dialog = true;
+    }
+
+    auto &old_first_db_message_id = d->first_database_message_id_by_index[search_messages_filter_index(filter)];
+    bool from_the_end = !from_message_id.is_valid() ||
+                        (d->last_message_id != MessageId() && from_message_id.get() > d->last_message_id.get()) ||
+                        from_message_id.get() >= MessageId::max().get();
+    if ((from_the_end ||
+         (old_first_db_message_id.is_valid() && old_first_db_message_id.get() <= from_message_id.get())) &&
+        (!old_first_db_message_id.is_valid() || first_added_message_id.get() < old_first_db_message_id.get())) {
+      old_first_db_message_id = first_added_message_id;
+      update_dialog = true;
+    }
+    if (update_dialog) {
+      on_dialog_updated(dialog_id, "search results");
+    }
+  }
+  it->second.first = total_count;
+}
+
+void MessagesManager::on_failed_dialog_messages_search(DialogId dialog_id, int64 random_id) {
+  if (!dialog_id.is_valid()) {
+    auto it = found_call_messages_.find(random_id);
+    CHECK(it != found_call_messages_.end());
+    found_call_messages_.erase(it);
+    return;
+  }
+
+  auto it = found_dialog_messages_.find(random_id);
+  CHECK(it != found_dialog_messages_.end());
+  found_dialog_messages_.erase(it);
+}
+
+void MessagesManager::on_get_messages_search_result(const string &query, int32 offset_date, DialogId offset_dialog_id,
+                                                    MessageId offset_message_id, int32 limit, int64 random_id,
+                                                    int32 total_count,
+                                                    vector<tl_object_ptr<telegram_api::Message>> &&messages) {
+  LOG(INFO) << "Receive " << messages.size() << " found messages";
+  auto it = found_messages_.find(random_id);
+  CHECK(it != found_messages_.end());
+
+  auto &result = it->second.second;
+  CHECK(result.empty());
+  for (auto &message : messages) {
+    auto dialog_id = get_message_dialog_id(message);
+    auto new_message = on_get_message(std::move(message), false, dialog_id.get_type() == DialogType::Channel, false,
+                                      false, "search messages");
+    if (new_message != FullMessageId()) {
+      CHECK(dialog_id == new_message.get_dialog_id());
+      result.push_back(new_message);
+    } else {
+      total_count--;
+    }
+  }
+  if (total_count < static_cast<int32>(result.size())) {
+    LOG(ERROR) << "Receive " << result.size() << " valid messages out of " << total_count << " in " << messages.size()
+               << " messages";
+    total_count = static_cast<int32>(result.size());
+  }
+  it->second.first = total_count;
+}
+
+void MessagesManager::on_failed_messages_search(int64 random_id) {
+  auto it = found_messages_.find(random_id);
+  CHECK(it != found_messages_.end());
+  found_messages_.erase(it);
+}
+
+void MessagesManager::on_get_recent_locations(DialogId dialog_id, int32 limit, int64 random_id, int32 total_count,
+                                              vector<tl_object_ptr<telegram_api::Message>> &&messages) {
+  LOG(INFO) << "Receive " << messages.size() << " recent locations in " << dialog_id;
+  auto it = found_dialog_recent_location_messages_.find(random_id);
+  CHECK(it != found_dialog_recent_location_messages_.end());
+
+  auto &result = it->second.second;
+  CHECK(result.empty());
+  for (auto &message : messages) {
+    auto new_message = on_get_message(std::move(message), false, dialog_id.get_type() == DialogType::Channel, false,
+                                      false, "get recent locations");
+    if (new_message != FullMessageId()) {
+      if (new_message.get_dialog_id() != dialog_id) {
+        LOG(ERROR) << "Receive " << new_message << " instead of a message in " << dialog_id;
+        continue;
+      }
+      auto m = get_message(new_message);
+      if (m->content->get_id() != MessageLiveLocation::ID) {
+        LOG(ERROR) << "Receive a message of wrong type " << m->content->get_id() << " in on_get_recent_locations in "
+                   << dialog_id;
+        continue;
+      }
+
+      result.push_back(new_message.get_message_id());
+    } else {
+      total_count--;
+    }
+  }
+  if (total_count < static_cast<int32>(result.size())) {
+    LOG(ERROR) << "Receive " << result.size() << " valid messages out of " << total_count << " in " << messages.size()
+               << " messages";
+    total_count = static_cast<int32>(result.size());
+  }
+  it->second.first = total_count;
+}
+
+void MessagesManager::on_get_recent_locations_failed(int64 random_id) {
+  auto it = found_dialog_recent_location_messages_.find(random_id);
+  CHECK(it != found_dialog_recent_location_messages_.end());
+  found_dialog_recent_location_messages_.erase(it);
+}
+
+void MessagesManager::delete_messages_from_updates(const vector<MessageId> &message_ids) {
+  std::unordered_map<DialogId, vector<int64>, DialogIdHash> deleted_message_ids;
+  std::unordered_map<DialogId, bool, DialogIdHash> need_update_dialog_pos;
+  for (auto message_id : message_ids) {
+    if (!message_id.is_valid() || !message_id.is_server()) {
+      LOG(ERROR) << "Incoming update tries to delete " << message_id;
+      continue;
+    }
+
+    Dialog *d = get_dialog_by_message_id(message_id);
+    if (d != nullptr) {
+      auto m = delete_message(d, message_id, true, &need_update_dialog_pos[d->dialog_id], "updates");
+      CHECK(m != nullptr);
+      CHECK(m->message_id == message_id);
+      deleted_message_ids[d->dialog_id].push_back(message_id.get());
+    }
+    if (last_clear_history_message_id_to_dialog_id_.count(message_id)) {
+      d = get_dialog(last_clear_history_message_id_to_dialog_id_[message_id]);
+      CHECK(d != nullptr);
+      auto m = delete_message(d, message_id, true, &need_update_dialog_pos[d->dialog_id], "updates");
+      CHECK(m == nullptr);
+    }
+  }
+  for (auto &it : need_update_dialog_pos) {
+    if (it.second) {
+      auto dialog_id = it.first;
+      Dialog *d = get_dialog(dialog_id);
+      CHECK(d != nullptr);
+      send_update_chat_last_message(d, "delete_messages_from_updates");
+    }
+  }
+  for (auto &it : deleted_message_ids) {
+    auto dialog_id = it.first;
+    send_update_delete_messages(dialog_id, std::move(it.second), true, false);
+  }
+}
+
+void MessagesManager::delete_dialog_messages_from_updates(DialogId dialog_id, const vector<MessageId> &message_ids) {
+  CHECK(dialog_id.get_type() == DialogType::Channel || dialog_id.get_type() == DialogType::SecretChat);
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    LOG(INFO) << "Ignore deleteChannelMessages for unknown " << dialog_id;
+    CHECK(dialog_id.get_type() == DialogType::Channel);
+    return;
+  }
+
+  vector<int64> deleted_message_ids;
+  bool need_update_dialog_pos = false;
+  for (auto message_id : message_ids) {
+    if (!message_id.is_valid() || (!message_id.is_server() && dialog_id.get_type() != DialogType::SecretChat)) {
+      LOG(ERROR) << "Incoming update tries to delete " << message_id;
+      continue;
+    }
+
+    if (delete_message(d, message_id, true, &need_update_dialog_pos, "updates") != nullptr) {
+      deleted_message_ids.push_back(message_id.get());
+    }
+  }
+  if (need_update_dialog_pos) {
+    send_update_chat_last_message(d, "delete_dialog_messages_from_updates");
+  }
+  send_update_delete_messages(dialog_id, std::move(deleted_message_ids), true, false);
+}
+
+bool MessagesManager::is_secret_message_content(int32 ttl, int32 content_type) {
+  if (ttl <= 0 || ttl > 60) {
+    return false;
+  }
+  switch (content_type) {
+    case MessageAnimation::ID:
+    case MessageAudio::ID:
+    case MessagePhoto::ID:
+    case MessageVideo::ID:
+    case MessageVideoNote::ID:
+    case MessageVoiceNote::ID:
+      return true;
+    case MessageContact::ID:
+    case MessageDocument::ID:
+    case MessageGame::ID:
+    case MessageInvoice::ID:
+    case MessageLiveLocation::ID:
+    case MessageLocation::ID:
+    case MessageSticker::ID:
+    case MessageText::ID:
+    case MessageUnsupported::ID:
+    case MessageVenue::ID:
+    case MessageExpiredPhoto::ID:
+    case MessageExpiredVideo::ID:
+    case MessageChatCreate::ID:
+    case MessageChatChangeTitle::ID:
+    case MessageChatChangePhoto::ID:
+    case MessageChatDeletePhoto::ID:
+    case MessageChatDeleteHistory::ID:
+    case MessageChatAddUsers::ID:
+    case MessageChatJoinedByLink::ID:
+    case MessageChatDeleteUser::ID:
+    case MessageChatMigrateTo::ID:
+    case MessageChannelCreate::ID:
+    case MessageChannelMigrateFrom::ID:
+    case MessagePinMessage::ID:
+    case MessageGameScore::ID:
+    case MessageScreenshotTaken::ID:
+    case MessageChatSetTtl::ID:
+    case MessageCall::ID:
+    case MessagePaymentSuccessful::ID:
+    case MessageContactRegistered::ID:
+    case MessageCustomServiceAction::ID:
+    case MessageWebsiteConnected::ID:
+      return false;
+    default:
+      UNREACHABLE();
+      return false;
+  }
+}
+
+bool MessagesManager::is_service_message_content(int32 content_type) {
+  switch (content_type) {
+    case MessageAnimation::ID:
+    case MessageAudio::ID:
+    case MessageContact::ID:
+    case MessageDocument::ID:
+    case MessageGame::ID:
+    case MessageInvoice::ID:
+    case MessageLiveLocation::ID:
+    case MessageLocation::ID:
+    case MessagePhoto::ID:
+    case MessageSticker::ID:
+    case MessageText::ID:
+    case MessageUnsupported::ID:
+    case MessageVenue::ID:
+    case MessageVideo::ID:
+    case MessageVideoNote::ID:
+    case MessageVoiceNote::ID:
+    case MessageExpiredPhoto::ID:
+    case MessageExpiredVideo::ID:
+      return false;
+    case MessageChatCreate::ID:
+    case MessageChatChangeTitle::ID:
+    case MessageChatChangePhoto::ID:
+    case MessageChatDeletePhoto::ID:
+    case MessageChatDeleteHistory::ID:
+    case MessageChatAddUsers::ID:
+    case MessageChatJoinedByLink::ID:
+    case MessageChatDeleteUser::ID:
+    case MessageChatMigrateTo::ID:
+    case MessageChannelCreate::ID:
+    case MessageChannelMigrateFrom::ID:
+    case MessagePinMessage::ID:
+    case MessageGameScore::ID:
+    case MessageScreenshotTaken::ID:
+    case MessageChatSetTtl::ID:
+    case MessageCall::ID:
+    case MessagePaymentSuccessful::ID:
+    case MessageContactRegistered::ID:
+    case MessageCustomServiceAction::ID:
+    case MessageWebsiteConnected::ID:
+      return true;
+    default:
+      UNREACHABLE();
+      return false;
+  }
+}
+
+bool MessagesManager::can_have_message_content_caption(int32 content_type) {
+  switch (content_type) {
+    case MessageAnimation::ID:
+    case MessageAudio::ID:
+    case MessageDocument::ID:
+    case MessagePhoto::ID:
+    case MessageVideo::ID:
+    case MessageVoiceNote::ID:
+      return true;
+    case MessageContact::ID:
+    case MessageGame::ID:
+    case MessageInvoice::ID:
+    case MessageLiveLocation::ID:
+    case MessageLocation::ID:
+    case MessageSticker::ID:
+    case MessageText::ID:
+    case MessageUnsupported::ID:
+    case MessageVenue::ID:
+    case MessageVideoNote::ID:
+    case MessageChatCreate::ID:
+    case MessageChatChangeTitle::ID:
+    case MessageChatChangePhoto::ID:
+    case MessageChatDeletePhoto::ID:
+    case MessageChatDeleteHistory::ID:
+    case MessageChatAddUsers::ID:
+    case MessageChatJoinedByLink::ID:
+    case MessageChatDeleteUser::ID:
+    case MessageChatMigrateTo::ID:
+    case MessageChannelCreate::ID:
+    case MessageChannelMigrateFrom::ID:
+    case MessagePinMessage::ID:
+    case MessageGameScore::ID:
+    case MessageScreenshotTaken::ID:
+    case MessageChatSetTtl::ID:
+    case MessageCall::ID:
+    case MessagePaymentSuccessful::ID:
+    case MessageContactRegistered::ID:
+    case MessageExpiredPhoto::ID:
+    case MessageExpiredVideo::ID:
+    case MessageCustomServiceAction::ID:
+    case MessageWebsiteConnected::ID:
+      return false;
+    default:
+      UNREACHABLE();
+      return false;
+  }
+}
+
+string MessagesManager::get_search_text(const Message *m) {
+  if (m->is_content_secret) {
+    return "";
+  }
+  switch (m->content->get_id()) {
+    case MessageText::ID: {
+      auto *text = static_cast<const MessageText *>(m->content.get());
+      if (!text->web_page_id.is_valid()) {
+        return text->text.text;
+      }
+      return PSTRING() << text->text.text << " "
+                       << td_->web_pages_manager_->get_web_page_search_text(text->web_page_id);
+    }
+    case MessageAnimation::ID: {
+      auto animation = static_cast<const MessageAnimation *>(m->content.get());
+      return PSTRING() << td_->animations_manager_->get_animation_search_text(animation->file_id) << " "
+                       << animation->caption.text;
+    }
+    case MessageAudio::ID: {
+      auto audio = static_cast<const MessageAudio *>(m->content.get());
+      return PSTRING() << td_->audios_manager_->get_audio_search_text(audio->file_id) << " " << audio->caption.text;
+    }
+    case MessageDocument::ID: {
+      auto document = static_cast<const MessageDocument *>(m->content.get());
+      return PSTRING() << td_->documents_manager_->get_document_search_text(document->file_id) << " "
+                       << document->caption.text;
+    }
+    case MessagePhoto::ID: {
+      auto photo = static_cast<const MessagePhoto *>(m->content.get());
+      return PSTRING() << photo->caption.text;
+    }
+    case MessageVideo::ID: {
+      auto video = static_cast<const MessageVideo *>(m->content.get());
+      return PSTRING() << td_->videos_manager_->get_video_search_text(video->file_id) << " " << video->caption.text;
+    }
+    case MessageContact::ID:
+    case MessageGame::ID:
+    case MessageInvoice::ID:
+    case MessageLiveLocation::ID:
+    case MessageLocation::ID:
+    case MessageSticker::ID:
+    case MessageUnsupported::ID:
+    case MessageVenue::ID:
+    case MessageVideoNote::ID:
+    case MessageVoiceNote::ID:
+    case MessageChatCreate::ID:
+    case MessageChatChangeTitle::ID:
+    case MessageChatChangePhoto::ID:
+    case MessageChatDeletePhoto::ID:
+    case MessageChatDeleteHistory::ID:
+    case MessageChatAddUsers::ID:
+    case MessageChatJoinedByLink::ID:
+    case MessageChatDeleteUser::ID:
+    case MessageChatMigrateTo::ID:
+    case MessageChannelCreate::ID:
+    case MessageChannelMigrateFrom::ID:
+    case MessagePinMessage::ID:
+    case MessageGameScore::ID:
+    case MessageScreenshotTaken::ID:
+    case MessageChatSetTtl::ID:
+    case MessageCall::ID:
+    case MessagePaymentSuccessful::ID:
+    case MessageExpiredPhoto::ID:
+    case MessageExpiredVideo::ID:
+    case MessageCustomServiceAction::ID:
+    case MessageWebsiteConnected::ID:
+      return "";
+    default:
+      UNREACHABLE();
+      return "";
+  }
+}
+
+bool MessagesManager::is_allowed_media_group_content(int32 content_type) {
+  switch (content_type) {
+    case MessagePhoto::ID:
+    case MessageVideo::ID:
+    case MessageExpiredPhoto::ID:
+    case MessageExpiredVideo::ID:
+      return true;
+    case MessageAnimation::ID:
+    case MessageAudio::ID:
+    case MessageContact::ID:
+    case MessageDocument::ID:
+    case MessageGame::ID:
+    case MessageInvoice::ID:
+    case MessageLiveLocation::ID:
+    case MessageLocation::ID:
+    case MessageSticker::ID:
+    case MessageText::ID:
+    case MessageUnsupported::ID:
+    case MessageVenue::ID:
+    case MessageVideoNote::ID:
+    case MessageVoiceNote::ID:
+    case MessageChatCreate::ID:
+    case MessageChatChangeTitle::ID:
+    case MessageChatChangePhoto::ID:
+    case MessageChatDeletePhoto::ID:
+    case MessageChatDeleteHistory::ID:
+    case MessageChatAddUsers::ID:
+    case MessageChatJoinedByLink::ID:
+    case MessageChatDeleteUser::ID:
+    case MessageChatMigrateTo::ID:
+    case MessageChannelCreate::ID:
+    case MessageChannelMigrateFrom::ID:
+    case MessagePinMessage::ID:
+    case MessageGameScore::ID:
+    case MessageScreenshotTaken::ID:
+    case MessageChatSetTtl::ID:
+    case MessageCall::ID:
+    case MessagePaymentSuccessful::ID:
+    case MessageContactRegistered::ID:
+    case MessageCustomServiceAction::ID:
+    case MessageWebsiteConnected::ID:
+      return false;
+    default:
+      UNREACHABLE();
+      return false;
+  }
+}
+
+bool MessagesManager::can_forward_message(DialogId from_dialog_id, const Message *m) {
+  if (m == nullptr) {
+    return false;
+  }
+  if (m->ttl > 0) {
+    return false;
+  }
+  switch (from_dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+    case DialogType::Channel:
+      // ok
+      break;
+    case DialogType::SecretChat:
+      return false;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      return false;
+  }
+
+  auto content_id = m->content->get_id();
+  return !is_service_message_content(content_id) && content_id != MessageUnsupported::ID &&
+         content_id != MessageExpiredPhoto::ID && content_id != MessageExpiredVideo::ID;
+}
+
+bool MessagesManager::can_delete_channel_message(DialogParticipantStatus status, const Message *m, bool is_bot) {
+  if (m == nullptr) {
+    return true;
+  }
+  if (m->message_id.is_local() || m->message_id.is_yet_unsent()) {
+    return true;
+  }
+
+  if (is_bot && G()->unix_time_cached() >= m->date + 2 * 86400) {
+    // bots can't delete messages older than 2 days
+    return false;
+  }
+
+  CHECK(m->message_id.is_server());
+  if (m->message_id.get_server_message_id().get() == 1) {
+    return false;
+  }
+  auto content_id = m->content->get_id();
+  if (content_id == MessageChannelMigrateFrom::ID || content_id == MessageChannelCreate::ID) {
+    return false;
+  }
+
+  if (status.can_delete_messages()) {
+    return true;
+  }
+
+  if (!m->is_outgoing) {
+    return false;
+  }
+
+  if (m->is_channel_post || is_service_message_content(content_id)) {
+    return status.can_post_messages();
+  }
+
+  return true;
+}
+
+bool MessagesManager::can_revoke_message(DialogId dialog_id, const Message *m) const {
+  if (m == nullptr) {
+    return false;
+  }
+  if (m->message_id.is_local()) {
+    return false;
+  }
+  if (dialog_id == DialogId(td_->contacts_manager_->get_my_id("can_revoke_message"))) {
+    return false;
+  }
+  if (m->message_id.is_yet_unsent()) {
+    return true;
+  }
+  CHECK(m->message_id.is_server());
+
+  bool is_appointed_administrator = false;
+  bool can_revoke_incoming = false;
+  const int32 DEFAULT_REVOKE_TIME_LIMIT = 2 * 86400;
+  int32 revoke_time_limit = G()->shared_config().get_option_integer("revoke_time_limit", DEFAULT_REVOKE_TIME_LIMIT);
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      can_revoke_incoming = G()->shared_config().get_option_boolean("revoke_pm_inbox");
+      revoke_time_limit = G()->shared_config().get_option_integer("revoke_pm_time_limit", DEFAULT_REVOKE_TIME_LIMIT);
+      break;
+    case DialogType::Chat:
+      is_appointed_administrator = td_->contacts_manager_->is_appointed_chat_administrator(dialog_id.get_chat_id());
+      break;
+    case DialogType::Channel:
+      return true;  // any server message that can be deleted will be deleted for all participants
+    case DialogType::SecretChat:
+      return !is_service_message_content(
+          m->content->get_id());  // all non-service messages will be deleted for everyone
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      return false;
+  }
+
+  return (((m->is_outgoing || can_revoke_incoming) && !is_service_message_content(m->content->get_id())) ||
+          is_appointed_administrator) &&
+         G()->unix_time_cached() - m->date <= revoke_time_limit;
+}
+
+void MessagesManager::delete_messages(DialogId dialog_id, const vector<MessageId> &input_message_ids, bool revoke,
+                                      Promise<Unit> &&promise) {
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return promise.set_error(Status::Error(6, "Chat is not found"));
+  }
+
+  if (input_message_ids.empty()) {
+    return promise.set_value(Unit());
+  }
+
+  auto dialog_type = dialog_id.get_type();
+  bool is_secret = dialog_type == DialogType::SecretChat;
+
+  vector<MessageId> message_ids;
+  message_ids.reserve(input_message_ids.size());
+  vector<MessageId> deleted_server_message_ids;
+  for (auto message_id : input_message_ids) {
+    if (!message_id.is_valid()) {
+      return promise.set_error(Status::Error(6, "Invalid message identifier"));
+    }
+    message_id = get_persistent_message_id(d, message_id);
+    message_ids.push_back(message_id);
+    if (get_message_force(d, message_id) != nullptr && (message_id.is_server() || is_secret)) {
+      deleted_server_message_ids.push_back(message_id);
+    }
+  }
+
+  bool is_bot = td_->auth_manager_->is_bot();
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+      if (is_bot) {
+        for (auto message_id : message_ids) {
+          if (message_id.is_server() && !can_revoke_message(dialog_id, get_message(d, message_id))) {
+            return promise.set_error(Status::Error(6, "Message can't be deleted"));
+          }
+        }
+      }
+      break;
+    case DialogType::Channel: {
+      auto dialog_status = td_->contacts_manager_->get_channel_status(dialog_id.get_channel_id());
+      for (auto message_id : message_ids) {
+        if (!can_delete_channel_message(dialog_status, get_message(d, message_id), is_bot)) {
+          return promise.set_error(Status::Error(6, "Message can't be deleted"));
+        }
+      }
+      break;
+    }
+    case DialogType::SecretChat:
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+
+  delete_messages_from_server(dialog_id, std::move(deleted_server_message_ids), revoke, 0, std::move(promise));
+
+  bool need_update_dialog_pos = false;
+  vector<int64> deleted_message_ids;
+  for (auto message_id : message_ids) {
+    auto m = delete_message(d, message_id, true, &need_update_dialog_pos, DELETE_MESSAGE_USER_REQUEST_SOURCE);
+    if (m == nullptr) {
+      LOG(INFO) << "Can't delete " << message_id << " because it is not found";
+    } else {
+      deleted_message_ids.push_back(m->message_id.get());
+    }
+  }
+
+  if (need_update_dialog_pos) {
+    send_update_chat_last_message(d, "delete_messages");
+  }
+  send_update_delete_messages(dialog_id, std::move(deleted_message_ids), true, false);
+}
+
+class MessagesManager::DeleteMessagesFromServerLogEvent {
+ public:
+  DialogId dialog_id_;
+  vector<MessageId> message_ids_;
+  bool revoke_;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    BEGIN_STORE_FLAGS();
+    STORE_FLAG(revoke_);
+    END_STORE_FLAGS();
+
+    td::store(dialog_id_, storer);
+    td::store(message_ids_, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    BEGIN_PARSE_FLAGS();
+    PARSE_FLAG(revoke_);
+    END_PARSE_FLAGS();
+
+    td::parse(dialog_id_, parser);
+    td::parse(message_ids_, parser);
+  }
+};
+
+void MessagesManager::delete_messages_from_server(DialogId dialog_id, vector<MessageId> message_ids, bool revoke,
+                                                  uint64 logevent_id, Promise<Unit> &&promise) {
+  if (message_ids.empty()) {
+    promise.set_value(Unit());
+    return;
+  }
+  LOG(INFO) << (revoke ? "Revoke " : "Delete ") << format::as_array(message_ids) << " in " << dialog_id
+            << " from server";
+
+  if (logevent_id == 0 && G()->parameters().use_message_db) {
+    DeleteMessagesFromServerLogEvent logevent;
+    logevent.dialog_id_ = dialog_id;
+    logevent.message_ids_ = message_ids;
+    logevent.revoke_ = revoke;
+
+    auto storer = LogEventStorerImpl<DeleteMessagesFromServerLogEvent>(logevent);
+    logevent_id =
+        BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::DeleteMessagesFromServer, storer);
+  }
+
+  if (logevent_id != 0) {
+    auto new_promise = PromiseCreator::lambda([logevent_id, promise = std::move(promise)](Result<Unit> result) mutable {
+      if (!G()->close_flag()) {
+        BinlogHelper::erase(G()->td_db()->get_binlog(), logevent_id);
+      }
+
+      promise.set_result(std::move(result));
+    });
+    promise = std::move(new_promise);
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+      td_->create_handler<DeleteMessagesQuery>(std::move(promise))->send(std::move(message_ids), revoke);
+      break;
+    case DialogType::Channel:
+      td_->create_handler<DeleteChannelMessagesQuery>(std::move(promise))
+          ->send(dialog_id.get_channel_id(), std::move(message_ids));
+      break;
+    case DialogType::SecretChat: {
+      vector<int64> random_ids;
+      auto d = get_dialog_force(dialog_id);
+      CHECK(d != nullptr);
+      for (auto &message_id : message_ids) {
+        auto *message = get_message(d, message_id);
+        if (message != nullptr) {
+          random_ids.push_back(message->random_id);
+        }
+      }
+      if (!random_ids.empty()) {
+        send_closure(G()->secret_chats_manager(), &SecretChatsManager::delete_messages, dialog_id.get_secret_chat_id(),
+                     std::move(random_ids), std::move(promise));
+      } else {
+        promise.set_value(Unit());
+      }
+      break;
+    }
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+}
+
+void MessagesManager::delete_dialog_history(DialogId dialog_id, bool remove_from_dialog_list, Promise<Unit> &&promise) {
+  LOG(INFO) << "Receive deleteChatHistory request to delete all messages in " << dialog_id
+            << ", remove_from_chat_list is " << remove_from_dialog_list;
+
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return promise.set_error(Status::Error(3, "Chat not found"));
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    return promise.set_error(Status::Error(3, "Chat info not found"));
+  }
+
+  auto dialog_type = dialog_id.get_type();
+  bool is_secret = false;
+  switch (dialog_type) {
+    case DialogType::User:
+    case DialogType::Chat:
+      // ok
+      break;
+    case DialogType::Channel:
+      if (is_broadcast_channel(dialog_id)) {
+        return promise.set_error(Status::Error(3, "Can't delete chat history in a channel"));
+      }
+      if (!get_dialog_username(dialog_id).empty()) {
+        return promise.set_error(Status::Error(3, "Can't delete chat history in a public supergroup"));
+      }
+      break;
+    case DialogType::SecretChat:
+      is_secret = true;
+      // ok
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      break;
+  }
+
+  auto last_new_message_id = d->last_new_message_id;
+  if (!is_secret && last_new_message_id == MessageId()) {
+    // TODO get dialog from the server and delete history from last message id
+  }
+
+  bool allow_error = d->messages == nullptr;
+
+  delete_all_dialog_messages(d, remove_from_dialog_list, true);
+
+  if (last_new_message_id.is_valid() && last_new_message_id == d->max_unavailable_message_id) {
+    // history has already been cleared, nothing to do
+    promise.set_value(Unit());
+    return;
+  }
+
+  set_dialog_max_unavailable_message_id(dialog_id, last_new_message_id, false, "delete_dialog_history");
+
+  delete_dialog_history_from_server(dialog_id, last_new_message_id, remove_from_dialog_list, allow_error, 0,
+                                    std::move(promise));
+}
+
+class MessagesManager::DeleteDialogHistoryFromServerLogEvent {
+ public:
+  DialogId dialog_id_;
+  MessageId max_message_id_;
+  bool remove_from_dialog_list_;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    BEGIN_STORE_FLAGS();
+    STORE_FLAG(remove_from_dialog_list_);
+    END_STORE_FLAGS();
+
+    td::store(dialog_id_, storer);
+    td::store(max_message_id_, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    BEGIN_PARSE_FLAGS();
+    PARSE_FLAG(remove_from_dialog_list_);
+    END_PARSE_FLAGS();
+
+    td::parse(dialog_id_, parser);
+    td::parse(max_message_id_, parser);
+  }
+};
+
+void MessagesManager::delete_dialog_history_from_server(DialogId dialog_id, MessageId max_message_id,
+                                                        bool remove_from_dialog_list, bool allow_error,
+                                                        uint64 logevent_id, Promise<Unit> &&promise) {
+  LOG(INFO) << "Delete history in " << dialog_id << " up to " << max_message_id << " from server";
+
+  if (logevent_id == 0 && G()->parameters().use_message_db) {
+    DeleteDialogHistoryFromServerLogEvent logevent;
+    logevent.dialog_id_ = dialog_id;
+    logevent.max_message_id_ = max_message_id;
+    logevent.remove_from_dialog_list_ = remove_from_dialog_list;
+
+    auto storer = LogEventStorerImpl<DeleteDialogHistoryFromServerLogEvent>(logevent);
+    logevent_id =
+        BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::DeleteDialogHistoryFromServer, storer);
+  }
+
+  if (logevent_id != 0) {
+    auto new_promise = PromiseCreator::lambda([logevent_id, promise = std::move(promise)](Result<Unit> result) mutable {
+      if (!G()->close_flag()) {
+        BinlogHelper::erase(G()->td_db()->get_binlog(), logevent_id);
+      }
+
+      promise.set_result(std::move(result));
+    });
+    promise = std::move(new_promise);
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+      td_->create_handler<DeleteHistoryQuery>(std::move(promise))
+          ->send(dialog_id, max_message_id, remove_from_dialog_list);
+      break;
+    case DialogType::Channel:
+      td_->create_handler<DeleteChannelHistoryQuery>(std::move(promise))
+          ->send(dialog_id.get_channel_id(), max_message_id, allow_error);
+      break;
+    case DialogType::SecretChat:
+      // TODO: use promise
+      send_closure(G()->secret_chats_manager(), &SecretChatsManager::delete_all_messages,
+                   dialog_id.get_secret_chat_id(), Promise<>());
+      promise.set_value(Unit());
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      break;
+  }
+}
+
+void MessagesManager::find_messages_from_user(const unique_ptr<Message> &m, UserId user_id,
+                                              vector<MessageId> &message_ids) {
+  if (m == nullptr) {
+    return;
+  }
+
+  find_messages_from_user(m->left, user_id, message_ids);
+
+  if (m->sender_user_id == user_id) {
+    message_ids.push_back(m->message_id);
+  }
+
+  find_messages_from_user(m->right, user_id, message_ids);
+}
+
+void MessagesManager::find_unread_mentions(const unique_ptr<Message> &m, vector<MessageId> &message_ids) {
+  if (m == nullptr) {
+    return;
+  }
+
+  find_unread_mentions(m->left, message_ids);
+
+  if (m->contains_unread_mention) {
+    message_ids.push_back(m->message_id);
+  }
+
+  find_unread_mentions(m->right, message_ids);
+}
+
+void MessagesManager::find_old_messages(const unique_ptr<Message> &m, MessageId max_message_id,
+                                        vector<MessageId> &message_ids) {
+  if (m == nullptr) {
+    return;
+  }
+
+  find_old_messages(m->left, max_message_id, message_ids);
+
+  if (m->message_id.get() <= max_message_id.get()) {
+    message_ids.push_back(m->message_id);
+
+    find_old_messages(m->right, max_message_id, message_ids);
+  }
+}
+
+void MessagesManager::find_unloadable_messages(const Dialog *d, int32 unload_before_date, const unique_ptr<Message> &m,
+                                               vector<MessageId> &message_ids, int32 &left_to_unload) const {
+  if (m == nullptr) {
+    return;
+  }
+
+  find_unloadable_messages(d, unload_before_date, m->left, message_ids, left_to_unload);
+
+  if (can_unload_message(d, m.get())) {
+    if (m->last_access_date <= unload_before_date) {
+      message_ids.push_back(m->message_id);
+    } else {
+      left_to_unload++;
+    }
+  }
+
+  find_unloadable_messages(d, unload_before_date, m->right, message_ids, left_to_unload);
+}
+
+void MessagesManager::delete_dialog_messages_from_user(DialogId dialog_id, UserId user_id, Promise<Unit> &&promise) {
+  bool is_bot = td_->auth_manager_->is_bot();
+  if (is_bot) {
+    return promise.set_error(Status::Error(3, "Method is not available for bots"));
+  }
+
+  LOG(INFO) << "Receive deleteChatMessagesFromUser request to delete all messages in " << dialog_id << " from the user "
+            << user_id;
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return promise.set_error(Status::Error(3, "Chat not found"));
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Write)) {
+    return promise.set_error(Status::Error(3, "Not enough rights"));
+  }
+
+  if (!td_->contacts_manager_->have_input_user(user_id)) {
+    return promise.set_error(Status::Error(3, "User not found"));
+  }
+
+  ChannelId channel_id;
+  DialogParticipantStatus channel_status = DialogParticipantStatus::Left();
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+    case DialogType::SecretChat:
+      return promise.set_error(Status::Error(3, "All messages from a user can be deleted only in supergroup chats"));
+    case DialogType::Channel: {
+      channel_id = dialog_id.get_channel_id();
+      auto channel_type = td_->contacts_manager_->get_channel_type(channel_id);
+      if (channel_type != ChannelType::Megagroup) {
+        return promise.set_error(Status::Error(3, "The method is available only for supergroup chats"));
+      }
+      channel_status = td_->contacts_manager_->get_channel_status(channel_id);
+      if (!channel_status.can_delete_messages()) {
+        return promise.set_error(Status::Error(5, "Need delete messages administator right in the supergroup chat"));
+      }
+      channel_id = dialog_id.get_channel_id();
+      break;
+    }
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      break;
+  }
+  CHECK(channel_id.is_valid());
+
+  if (G()->parameters().use_message_db) {
+    LOG(INFO) << "Delete all messages from " << user_id << " in " << dialog_id << " from database";
+    G()->td_db()->get_messages_db_async()->delete_dialog_messages_from_user(dialog_id, user_id,
+                                                                            Auto());  // TODO Promise
+  }
+
+  vector<MessageId> message_ids;
+  find_messages_from_user(d->messages, user_id, message_ids);
+
+  vector<int64> deleted_message_ids;
+  bool need_update_dialog_pos = false;
+  for (auto message_id : message_ids) {
+    auto m = get_message(d, message_id);
+    CHECK(m != nullptr);
+    CHECK(m->sender_user_id == user_id);
+    CHECK(m->message_id == message_id);
+    if (can_delete_channel_message(channel_status, m, is_bot)) {
+      deleted_message_ids.push_back(message_id.get());
+      auto p = delete_message(d, message_id, true, &need_update_dialog_pos, "delete messages from user");
+      CHECK(p.get() == m);
+    }
+  }
+
+  if (need_update_dialog_pos) {
+    send_update_chat_last_message(d, "delete_messages_from_user");
+  }
+
+  send_update_delete_messages(dialog_id, std::move(deleted_message_ids), true, false);
+
+  delete_all_channel_messages_from_user_on_server(channel_id, user_id, 0, std::move(promise));
+}
+
+class MessagesManager::DeleteAllChannelMessagesFromUserOnServerLogEvent {
+ public:
+  ChannelId channel_id_;
+  UserId user_id_;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(channel_id_, storer);
+    td::store(user_id_, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(channel_id_, parser);
+    td::parse(user_id_, parser);
+  }
+};
+
+void MessagesManager::delete_all_channel_messages_from_user_on_server(ChannelId channel_id, UserId user_id,
+                                                                      uint64 logevent_id, Promise<Unit> &&promise) {
+  if (logevent_id == 0 && G()->parameters().use_chat_info_db) {
+    DeleteAllChannelMessagesFromUserOnServerLogEvent logevent;
+    logevent.channel_id_ = channel_id;
+    logevent.user_id_ = user_id;
+
+    auto storer = LogEventStorerImpl<DeleteAllChannelMessagesFromUserOnServerLogEvent>(logevent);
+    logevent_id = BinlogHelper::add(G()->td_db()->get_binlog(),
+                                    LogEvent::HandlerType::DeleteAllChannelMessagesFromUserOnServer, storer);
+  }
+
+  if (logevent_id != 0) {
+    auto new_promise = PromiseCreator::lambda([logevent_id, promise = std::move(promise)](Result<Unit> result) mutable {
+      if (!G()->close_flag()) {
+        BinlogHelper::erase(G()->td_db()->get_binlog(), logevent_id);
+      }
+
+      promise.set_result(std::move(result));
+    });
+    promise = std::move(new_promise);
+  }
+
+  td_->create_handler<DeleteUserHistoryQuery>(std::move(promise))->send(channel_id, user_id);
+}
+
+void MessagesManager::unload_dialog(DialogId dialog_id) {
+  Dialog *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+
+  vector<MessageId> to_unload_message_ids;
+  int32 left_to_unload = 0;
+  find_unloadable_messages(d, G()->unix_time_cached() - DIALOG_UNLOAD_DELAY + 2, d->messages, to_unload_message_ids,
+                           left_to_unload);
+
+  vector<int64> unloaded_message_ids;
+  for (auto message_id : to_unload_message_ids) {
+    unload_message(d, message_id);
+    unloaded_message_ids.push_back(message_id.get());
+  }
+
+  if (!unloaded_message_ids.empty()) {
+    if (!G()->parameters().use_message_db) {
+      d->have_full_history = false;
+    }
+
+    send_closure_later(
+        G()->td(), &Td::send_update,
+        make_tl_object<td_api::updateDeleteMessages>(dialog_id.get(), std::move(unloaded_message_ids), false, true));
+  }
+
+  if (left_to_unload > 0) {
+    LOG(INFO) << "Need to unload " << left_to_unload << " messages more in " << dialog_id;
+    pending_unload_dialog_timeout_.add_timeout_in(d->dialog_id.get(), DIALOG_UNLOAD_DELAY);
+  }
+}
+
+void MessagesManager::delete_all_dialog_messages(Dialog *d, bool remove_from_dialog_list, bool is_permanent) {
+  CHECK(d != nullptr);
+  if (is_debug_message_op_enabled()) {
+    d->debug_message_op.emplace_back(Dialog::MessageOp::DeleteAll, MessageId(), -1, remove_from_dialog_list, false,
+                                     false, "");
+  }
+
+  if (d->server_unread_count + d->local_unread_count > 0) {
+    MessageId max_message_id =
+        d->last_database_message_id.is_valid() ? d->last_database_message_id : d->last_new_message_id;
+    if (max_message_id.is_valid()) {
+      read_history_inbox(d->dialog_id, max_message_id, -1, "delete_all_dialog_messages");
+    }
+    if (d->server_unread_count != 0 || d->local_unread_count != 0) {
+      set_dialog_last_read_inbox_message_id(d, MessageId::min(), 0, 0, true, "delete_all_dialog_messages");
+    }
+  }
+
+  if (d->unread_mention_count > 0) {
+    d->unread_mention_count = 0;
+    d->message_count_by_index[search_messages_filter_index(SearchMessagesFilter::UnreadMention)] = 0;
+    send_update_chat_unread_mention_count(d);
+  }
+
+  bool has_last_message_id = d->last_message_id != MessageId();
+  int32 last_message_date = 0;
+  MessageId last_clear_history_message_id;
+  if (!remove_from_dialog_list) {
+    if (has_last_message_id) {
+      auto m = get_message(d, d->last_message_id);
+      CHECK(m != nullptr);
+      last_message_date = m->date;
+      last_clear_history_message_id = d->last_message_id;
+    } else {
+      last_message_date = d->last_clear_history_date;
+      last_clear_history_message_id = d->last_clear_history_message_id;
+    }
+  }
+
+  vector<int64> deleted_message_ids;
+  do_delete_all_dialog_messages(d, d->messages, deleted_message_ids);
+  delete_all_dialog_messages_from_database(d->dialog_id, MessageId::max(), "delete_all_dialog_messages");
+  if (is_permanent) {
+    for (auto id : deleted_message_ids) {
+      d->deleted_message_ids.insert(MessageId{id});
+    }
+  }
+
+  if (d->reply_markup_message_id != MessageId()) {
+    set_dialog_reply_markup(d, MessageId());
+  }
+
+  set_dialog_first_database_message_id(d, MessageId(), "delete_all_dialog_messages");
+  set_dialog_last_database_message_id(d, MessageId(), "delete_all_dialog_messages");
+  set_dialog_last_clear_history_date(d, last_message_date, last_clear_history_message_id, "delete_all_dialog_messages");
+  d->last_read_all_mentions_message_id = MessageId();  // it is not needed anymore
+  std::fill(d->message_count_by_index.begin(), d->message_count_by_index.end(), 0);
+
+  if (has_last_message_id) {
+    set_dialog_last_message_id(d, MessageId(), "delete_all_dialog_messages");
+    send_update_chat_last_message(d, "delete_all_dialog_messages");
+  }
+  if (remove_from_dialog_list && d->pinned_order != DEFAULT_ORDER) {
+    set_dialog_is_pinned(d, false);
+  }
+  update_dialog_pos(d, remove_from_dialog_list, "delete_all_dialog_messages");
+
+  on_dialog_updated(d->dialog_id, "delete_all_dialog_messages");
+
+  send_update_delete_messages(d->dialog_id, std::move(deleted_message_ids), is_permanent, false);
+}
+
+void MessagesManager::delete_dialog(DialogId dialog_id) {
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return;
+  }
+
+  delete_all_dialog_messages(d, true, false);
+  if (dialog_id.get_type() != DialogType::SecretChat) {
+    d->have_full_history = false;
+    d->need_restore_reply_markup = true;
+  }
+
+  close_dialog(d);
+}
+
+void MessagesManager::read_all_dialog_mentions(DialogId dialog_id, Promise<Unit> &&promise) {
+  bool is_bot = td_->auth_manager_->is_bot();
+  if (is_bot) {
+    return promise.set_error(Status::Error(3, "Method is not available for bots"));
+  }
+
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return promise.set_error(Status::Error(3, "Chat not found"));
+  }
+
+  LOG(INFO) << "Receive readAllChatMentions request in " << dialog_id << " with " << d->unread_mention_count
+            << " unread mentions";
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    return promise.set_error(Status::Error(3, "Chat is not accessible"));
+  }
+
+  if (d->last_new_message_id.get() > d->last_read_all_mentions_message_id.get()) {
+    d->last_read_all_mentions_message_id = d->last_new_message_id;
+    on_dialog_updated(dialog_id, "read_all_mentions");
+  }
+
+  vector<MessageId> message_ids;
+  find_unread_mentions(d->messages, message_ids);
+
+  LOG(INFO) << "Found " << message_ids.size() << " messages with unread mentions in memory";
+  bool is_update_sent = false;
+  for (auto message_id : message_ids) {
+    auto m = get_message(d, message_id);
+    CHECK(m != nullptr);
+    CHECK(m->contains_unread_mention);
+    CHECK(m->message_id == message_id);
+    m->contains_unread_mention = false;
+
+    send_closure(G()->td(), &Td::send_update,
+                 make_tl_object<td_api::updateMessageMentionRead>(dialog_id.get(), m->message_id.get(), 0));
+    is_update_sent = true;
+    on_message_changed(d, m, "read_all_mentions");
+  }
+
+  if (d->unread_mention_count != 0) {
+    d->unread_mention_count = 0;
+    d->message_count_by_index[search_messages_filter_index(SearchMessagesFilter::UnreadMention)] = 0;
+    if (!is_update_sent) {
+      send_update_chat_unread_mention_count(d);
+    } else {
+      LOG(INFO) << "Update unread mention message count in " << dialog_id << " to " << d->unread_mention_count;
+      on_dialog_updated(dialog_id, "read_all_mentions");
+    }
+  }
+
+  read_all_dialog_mentions_on_server(dialog_id, 0, std::move(promise));
+}
+
+class MessagesManager::ReadAllDialogMentionsOnServerLogEvent {
+ public:
+  DialogId dialog_id_;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(dialog_id_, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(dialog_id_, parser);
+  }
+};
+
+void MessagesManager::read_all_dialog_mentions_on_server(DialogId dialog_id, uint64 logevent_id,
+                                                         Promise<Unit> &&promise) {
+  if (logevent_id == 0 && G()->parameters().use_message_db) {
+    ReadAllDialogMentionsOnServerLogEvent logevent;
+    logevent.dialog_id_ = dialog_id;
+
+    auto storer = LogEventStorerImpl<ReadAllDialogMentionsOnServerLogEvent>(logevent);
+    logevent_id =
+        BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::ReadAllDialogMentionsOnServer, storer);
+  }
+
+  if (logevent_id != 0) {
+    auto new_promise = PromiseCreator::lambda([logevent_id, promise = std::move(promise)](Result<Unit> result) mutable {
+      if (!G()->close_flag()) {
+        BinlogHelper::erase(G()->td_db()->get_binlog(), logevent_id);
+      }
+
+      promise.set_result(std::move(result));
+    });
+    promise = std::move(new_promise);
+  }
+
+  td_->create_handler<ReadAllMentionsQuery>(std::move(promise))->send(dialog_id);
+}
+
+void MessagesManager::read_message_content_from_updates(MessageId message_id) {
+  if (!message_id.is_valid() || !message_id.is_server()) {
+    LOG(ERROR) << "Incoming update tries to read content of " << message_id;
+    return;
+  }
+
+  Dialog *d = get_dialog_by_message_id(message_id);
+  if (d != nullptr) {
+    Message *m = get_message(d, message_id);
+    CHECK(m != nullptr);
+    read_message_content(d, m, false, "read_message_content_from_updates");
+  }
+}
+
+void MessagesManager::read_channel_message_content_from_updates(Dialog *d, MessageId message_id) {
+  if (!message_id.is_valid() || !message_id.is_server()) {
+    LOG(ERROR) << "Incoming update tries to read content of " << message_id << " in " << d->dialog_id;
+    return;
+  }
+
+  Message *m = get_message_force(d, message_id);
+  if (m != nullptr) {
+    read_message_content(d, m, false, "read_channel_message_content_from_updates");
+  }
+}
+
+bool MessagesManager::update_opened_message_content(Message *m) {
+  switch (m->content->get_id()) {
+    case MessageVideoNote::ID: {
+      auto content = static_cast<MessageVideoNote *>(m->content.get());
+      if (content->is_viewed) {
+        return false;
+      }
+      content->is_viewed = true;
+      return true;
+    }
+    case MessageVoiceNote::ID: {
+      auto content = static_cast<MessageVoiceNote *>(m->content.get());
+      if (content->is_listened) {
+        return false;
+      }
+      content->is_listened = true;
+      return true;
+    }
+    default:
+      return false;
+  }
+}
+
+bool MessagesManager::read_message_content(Dialog *d, Message *m, bool is_local_read, const char *source) {
+  CHECK(m != nullptr) << source;
+  bool is_mention_read = update_message_contains_unread_mention(d, m, false, "read_message_content");
+  bool is_content_read = update_opened_message_content(m) | ttl_on_open(d, m, Time::now(), is_local_read);
+
+  if (is_mention_read || is_content_read) {
+    on_message_changed(d, m, "read_message_content");
+    if (is_content_read) {
+      send_closure(G()->td(), &Td::send_update,
+                   make_tl_object<td_api::updateMessageContentOpened>(d->dialog_id.get(), m->message_id.get()));
+    }
+    return true;
+  }
+  return false;
+}
+
+void MessagesManager::read_history_inbox(DialogId dialog_id, MessageId max_message_id, int32 unread_count,
+                                         const char *source) {
+  if (td_->auth_manager_->is_bot()) {
+    return;
+  }
+
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d != nullptr) {
+    if (unread_count < 0) {
+      if (!max_message_id.is_valid()) {
+        LOG(ERROR) << "Receive read inbox update in " << dialog_id << " up to " << max_message_id << " from " << source;
+        return;
+      }
+    } else {
+      if (!max_message_id.is_valid() && max_message_id != MessageId()) {
+        LOG(ERROR) << "Receive read inbox history in " << dialog_id << " up to " << max_message_id << " from "
+                   << source;
+        return;
+      }
+    }
+    if (d->is_last_read_inbox_message_id_inited && max_message_id.get() <= d->last_read_inbox_message_id.get()) {
+      LOG(INFO) << "Receive read inbox update in " << dialog_id << " up to " << max_message_id << " from " << source
+                << ", but all messages have already been read up to " << d->last_read_inbox_message_id;
+      return;
+    }
+
+    if (max_message_id != MessageId() && max_message_id.is_yet_unsent()) {
+      LOG(ERROR) << "Try to update last read inbox message in " << dialog_id << " with " << max_message_id << " from "
+                 << source;
+      return;
+    }
+
+    if (unread_count > 0 && max_message_id.get() >= d->last_new_message_id.get() &&
+        max_message_id.get() >= d->last_message_id.get() && max_message_id.get() >= d->last_database_message_id.get()) {
+      LOG(INFO) << "Have unknown " << unread_count << " unread messages in " << dialog_id;
+      unread_count = 0;
+    }
+
+    LOG_IF(INFO, d->last_new_message_id.is_valid() && max_message_id.get() > d->last_new_message_id.get() &&
+                     max_message_id.is_server() && dialog_id.get_type() != DialogType::Channel &&
+                     !running_get_difference_)
+        << "Receive read inbox update up to unknown " << max_message_id << " in " << dialog_id << " from " << source
+        << ". Last new is " << d->last_new_message_id << ", unread_count = " << unread_count
+        << ". Possible only for deleted incoming message. " << td_->updates_manager_->get_state();
+
+    if (dialog_id.get_type() == DialogType::SecretChat) {
+      // TODO: protect with logevent
+      suffix_load_till_message_id(
+          d, d->last_read_inbox_message_id,
+          PromiseCreator::lambda([actor_id = actor_id(this), dialog_id, from_message_id = max_message_id,
+                                  till_message_id = d->last_read_inbox_message_id,
+                                  timestamp = Time::now()](Result<Unit>) {
+            send_closure(actor_id, &MessagesManager::ttl_read_history_inbox, dialog_id, from_message_id,
+                         till_message_id, timestamp);
+          }));
+    }
+
+    int32 local_unread_count = 0;
+    int32 server_unread_count = 0;
+    if (dialog_id != DialogId(td_->contacts_manager_->get_my_id("read_history_inbox"))) {
+      MessagesConstIterator it(d, MessageId::max());
+      while (*it != nullptr && (*it)->message_id.get() > max_message_id.get()) {
+        if (!(*it)->is_outgoing) {
+          if ((*it)->message_id.is_server()) {
+            server_unread_count++;
+          } else {
+            CHECK((*it)->message_id.is_local());
+            local_unread_count++;
+          }
+        }
+        --it;
+      }
+    }
+    if (unread_count >= 0) {
+      if (unread_count < server_unread_count) {
+        LOG(ERROR) << "Receive unread_count = " << unread_count << ", but have at least " << server_unread_count
+                   << " unread messages in " << dialog_id;
+      } else {
+        server_unread_count = unread_count;
+      }
+    }
+
+    set_dialog_last_read_inbox_message_id(d, max_message_id, server_unread_count, local_unread_count, true, source);
+  } else {
+    LOG(INFO) << "Receive read inbox about unknown " << dialog_id << " from " << source;
+  }
+}
+
+void MessagesManager::read_history_outbox(DialogId dialog_id, MessageId max_message_id, int32 read_date) {
+  if (td_->auth_manager_->is_bot()) {
+    return;
+  }
+
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d != nullptr) {
+    if (!max_message_id.is_valid()) {
+      LOG(ERROR) << "Receive read outbox update in " << dialog_id << " with " << max_message_id;
+      return;
+    }
+    if (max_message_id.get() <= d->last_read_outbox_message_id.get()) {
+      LOG(INFO) << "Receive read outbox update up to " << max_message_id
+                << ", but all messages have already been read up to " << d->last_read_outbox_message_id;
+      return;
+    }
+
+    if (max_message_id.is_yet_unsent()) {
+      LOG(ERROR) << "Try to update last read outbox message with " << max_message_id;
+      return;
+    }
+
+    // it is impossible for just sent outgoing messages because updates are ordered by pts
+    LOG_IF(INFO, d->last_new_message_id.is_valid() && max_message_id.get() > d->last_new_message_id.get() &&
+                     dialog_id.get_type() != DialogType::Channel)
+        << "Receive read outbox update about unknown " << max_message_id << " in " << dialog_id << " with last new "
+        << d->last_new_message_id << ". Possible only for deleted outgoing message. "
+        << td_->updates_manager_->get_state();
+
+    if (dialog_id.get_type() == DialogType::SecretChat) {
+      double server_time = Time::now();
+      double read_time = server_time;
+      if (read_date <= 0) {
+        LOG(ERROR) << "Receive wrong read date " << read_date << " in " << dialog_id;
+      } else if (read_date < server_time) {
+        read_time = read_date;
+      }
+      // TODO: protect with logevent
+      suffix_load_till_message_id(
+          d, d->last_read_outbox_message_id,
+          PromiseCreator::lambda([actor_id = actor_id(this), dialog_id, from_message_id = max_message_id,
+                                  till_message_id = d->last_read_outbox_message_id, read_time](Result<Unit>) {
+            send_closure(actor_id, &MessagesManager::ttl_read_history_outbox, dialog_id, from_message_id,
+                         till_message_id, read_time);
+          }));
+    }
+
+    set_dialog_last_read_outbox_message_id(d, max_message_id);
+  } else {
+    LOG(INFO) << "Receive read outbox update about unknown " << dialog_id;
+  }
+}
+
+void MessagesManager::recalc_unread_message_count() {
+  if (td_->auth_manager_->is_bot() || !need_unread_count_recalc_) {
+    return;
+  }
+  need_unread_count_recalc_ = false;
+  is_unread_count_inited_ = true;
+
+  int32 total_count = 0;
+  int32 muted_count = 0;
+  for (auto &dialog_date : ordered_server_dialogs_) {
+    auto dialog_id = dialog_date.get_dialog_id();
+    Dialog *d = get_dialog(dialog_id);
+    CHECK(d != nullptr);
+    int unread_count = d->server_unread_count + d->local_unread_count;
+    if (d->order != DEFAULT_ORDER && unread_count > 0) {
+      total_count += unread_count;
+      if (d->notification_settings.mute_until != 0) {
+        muted_count += unread_count;
+      } else {
+        LOG(DEBUG) << "Have " << unread_count << " messages in unmuted " << dialog_id;
+      }
+    }
+  }
+
+  if (unread_message_total_count_ != total_count || unread_message_muted_count_ != muted_count) {
+    unread_message_total_count_ = total_count;
+    unread_message_muted_count_ = muted_count;
+    send_update_unread_message_count(DialogId(), true, "recalc_unread_message_count");
+  }
+}
+
+void MessagesManager::set_dialog_last_read_inbox_message_id(Dialog *d, MessageId message_id, int32 server_unread_count,
+                                                            int32 local_unread_count, bool force_update,
+                                                            const char *source) {
+  if (td_->auth_manager_->is_bot()) {
+    return;
+  }
+
+  CHECK(d != nullptr);
+  LOG(INFO) << "Update last read inbox message in " << d->dialog_id << " from " << d->last_read_inbox_message_id
+            << " to " << message_id << " and update unread message count from " << d->server_unread_count << " + "
+            << d->local_unread_count << " to " << server_unread_count << " + " << local_unread_count << " from "
+            << source;
+  if (message_id != MessageId::min()) {
+    d->last_read_inbox_message_id = message_id;
+    d->is_last_read_inbox_message_id_inited = true;
+  }
+  int32 old_unread_count = d->server_unread_count + d->local_unread_count;
+  d->server_unread_count = server_unread_count;
+  d->local_unread_count = local_unread_count;
+  int32 new_unread_count = d->server_unread_count + d->local_unread_count;
+  int32 delta = new_unread_count - old_unread_count;
+  if (delta != 0 && d->order != DEFAULT_ORDER && is_unread_count_inited_) {
+    unread_message_total_count_ += delta;
+    if (d->notification_settings.mute_until != 0) {
+      unread_message_muted_count_ += delta;
+    }
+    send_update_unread_message_count(d->dialog_id, force_update, source);
+  }
+
+  send_update_chat_read_inbox(d, force_update, source);
+}
+
+void MessagesManager::set_dialog_last_read_outbox_message_id(Dialog *d, MessageId message_id) {
+  if (td_->auth_manager_->is_bot()) {
+    return;
+  }
+
+  CHECK(d != nullptr);
+  LOG(INFO) << "Update last read outbox message in " << d->dialog_id << " from " << d->last_read_outbox_message_id
+            << " to " << message_id;
+  d->last_read_outbox_message_id = message_id;
+  d->is_last_read_outbox_message_id_inited = true;
+  send_update_chat_read_outbox(d);
+}
+
+void MessagesManager::set_dialog_max_unavailable_message_id(DialogId dialog_id, MessageId max_unavailable_message_id,
+                                                            bool from_update, const char *source) {
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d != nullptr) {
+    if (d->last_new_message_id.is_valid() && max_unavailable_message_id.get() > d->last_new_message_id.get()) {
+      LOG(ERROR) << "Tried to set " << dialog_id << " max unavailable message id to " << max_unavailable_message_id
+                 << " from " << source << ", but last new message id is " << d->last_new_message_id;
+      max_unavailable_message_id = d->last_new_message_id;
+    }
+
+    if (d->max_unavailable_message_id == max_unavailable_message_id) {
+      return;
+    }
+
+    if (max_unavailable_message_id.is_valid() && max_unavailable_message_id.is_yet_unsent()) {
+      LOG(ERROR) << "Try to update " << dialog_id << " last read outbox message with " << max_unavailable_message_id
+                 << " from " << source;
+      return;
+    }
+    LOG(INFO) << "Set max unavailable message id to " << max_unavailable_message_id << " in " << dialog_id << " from "
+              << source;
+
+    on_dialog_updated(dialog_id, "set_dialog_max_unavailable_message_id");
+
+    if (d->max_unavailable_message_id.get() > max_unavailable_message_id.get()) {
+      d->max_unavailable_message_id = max_unavailable_message_id;
+      return;
+    }
+
+    d->max_unavailable_message_id = max_unavailable_message_id;
+
+    vector<MessageId> message_ids;
+    find_old_messages(d->messages, max_unavailable_message_id, message_ids);
+
+    vector<int64> deleted_message_ids;
+    bool need_update_dialog_pos = false;
+    for (auto message_id : message_ids) {
+      if (message_id.is_yet_unsent()) {
+        continue;
+      }
+
+      auto m = get_message(d, message_id);
+      CHECK(m != nullptr);
+      CHECK(m->message_id.get() <= max_unavailable_message_id.get());
+      CHECK(m->message_id == message_id);
+      deleted_message_ids.push_back(message_id.get());
+      auto p =
+          delete_message(d, message_id, !from_update, &need_update_dialog_pos, "set_dialog_max_unavailable_message_id");
+      CHECK(p.get() == m);
+    }
+
+    if (need_update_dialog_pos) {
+      send_update_chat_last_message(d, "set_dialog_max_unavailable_message_id");
+    }
+
+    send_update_delete_messages(dialog_id, std::move(deleted_message_ids), !from_update, false);
+
+    if (d->server_unread_count + d->local_unread_count > 0) {
+      read_history_inbox(dialog_id, max_unavailable_message_id, -1, "set_dialog_max_unavailable_message_id");
+    }
+  } else {
+    LOG(INFO) << "Receive max unavailable message identifier in unknown " << dialog_id << " from " << source;
+  }
+}
+
+tl_object_ptr<td_api::MessageContent> MessagesManager::get_message_content_object(const MessageContent *content,
+                                                                                  int32 message_date,
+                                                                                  bool is_content_secret) const {
+  CHECK(content != nullptr);
+  switch (content->get_id()) {
+    case MessageAnimation::ID: {
+      const MessageAnimation *m = static_cast<const MessageAnimation *>(content);
+      return make_tl_object<td_api::messageAnimation>(
+          td_->animations_manager_->get_animation_object(m->file_id, "get_message_content_object"),
+          get_formatted_text_object(m->caption), is_content_secret);
+    }
+    case MessageAudio::ID: {
+      const MessageAudio *m = static_cast<const MessageAudio *>(content);
+      return make_tl_object<td_api::messageAudio>(td_->audios_manager_->get_audio_object(m->file_id),
+                                                  get_formatted_text_object(m->caption));
+    }
+    case MessageContact::ID: {
+      const MessageContact *m = static_cast<const MessageContact *>(content);
+      return make_tl_object<td_api::messageContact>(m->contact.get_contact_object());
+    }
+    case MessageDocument::ID: {
+      const MessageDocument *m = static_cast<const MessageDocument *>(content);
+      return make_tl_object<td_api::messageDocument>(td_->documents_manager_->get_document_object(m->file_id),
+                                                     get_formatted_text_object(m->caption));
+    }
+    case MessageGame::ID: {
+      const MessageGame *m = static_cast<const MessageGame *>(content);
+      return make_tl_object<td_api::messageGame>(m->game.get_game_object(td_));
+    }
+    case MessageInvoice::ID: {
+      const MessageInvoice *m = static_cast<const MessageInvoice *>(content);
+      return make_tl_object<td_api::messageInvoice>(
+          m->title, m->description, get_photo_object(td_->file_manager_.get(), &m->photo), m->invoice.currency,
+          m->total_amount, m->start_parameter, m->invoice.is_test, m->invoice.need_shipping_address,
+          m->receipt_message_id.get());
+    }
+    case MessageLiveLocation::ID: {
+      const MessageLiveLocation *m = static_cast<const MessageLiveLocation *>(content);
+      auto passed = max(G()->unix_time_cached() - message_date, 0);
+      return make_tl_object<td_api::messageLocation>(m->location.get_location_object(), m->period,
+                                                     max(0, m->period - passed));
+    }
+    case MessageLocation::ID: {
+      const MessageLocation *m = static_cast<const MessageLocation *>(content);
+      return make_tl_object<td_api::messageLocation>(m->location.get_location_object(), 0, 0);
+    }
+    case MessagePhoto::ID: {
+      const MessagePhoto *m = static_cast<const MessagePhoto *>(content);
+      return make_tl_object<td_api::messagePhoto>(get_photo_object(td_->file_manager_.get(), &m->photo),
+                                                  get_formatted_text_object(m->caption), is_content_secret);
+    }
+    case MessageSticker::ID: {
+      const MessageSticker *m = static_cast<const MessageSticker *>(content);
+      return make_tl_object<td_api::messageSticker>(td_->stickers_manager_->get_sticker_object(m->file_id));
+    }
+    case MessageText::ID: {
+      const MessageText *m = static_cast<const MessageText *>(content);
+      return make_tl_object<td_api::messageText>(get_formatted_text_object(m->text),
+                                                 td_->web_pages_manager_->get_web_page_object(m->web_page_id));
+    }
+    case MessageUnsupported::ID: {
+      return make_tl_object<td_api::messageUnsupported>();
+    }
+    case MessageVenue::ID: {
+      const MessageVenue *m = static_cast<const MessageVenue *>(content);
+      return make_tl_object<td_api::messageVenue>(m->venue.get_venue_object());
+    }
+    case MessageVideo::ID: {
+      const MessageVideo *m = static_cast<const MessageVideo *>(content);
+      return make_tl_object<td_api::messageVideo>(td_->videos_manager_->get_video_object(m->file_id),
+                                                  get_formatted_text_object(m->caption), is_content_secret);
+    }
+    case MessageVideoNote::ID: {
+      const MessageVideoNote *m = static_cast<const MessageVideoNote *>(content);
+      return make_tl_object<td_api::messageVideoNote>(td_->video_notes_manager_->get_video_note_object(m->file_id),
+                                                      m->is_viewed, is_content_secret);
+    }
+    case MessageVoiceNote::ID: {
+      const MessageVoiceNote *m = static_cast<const MessageVoiceNote *>(content);
+      return make_tl_object<td_api::messageVoiceNote>(td_->voice_notes_manager_->get_voice_note_object(m->file_id),
+                                                      get_formatted_text_object(m->caption), m->is_listened);
+    }
+    case MessageChatCreate::ID: {
+      const MessageChatCreate *m = static_cast<const MessageChatCreate *>(content);
+      return make_tl_object<td_api::messageBasicGroupChatCreate>(
+          m->title, td_->contacts_manager_->get_user_ids_object(m->participant_user_ids));
+    }
+    case MessageChatChangeTitle::ID: {
+      const MessageChatChangeTitle *m = static_cast<const MessageChatChangeTitle *>(content);
+      return make_tl_object<td_api::messageChatChangeTitle>(m->title);
+    }
+    case MessageChatChangePhoto::ID: {
+      const MessageChatChangePhoto *m = static_cast<const MessageChatChangePhoto *>(content);
+      return make_tl_object<td_api::messageChatChangePhoto>(get_photo_object(td_->file_manager_.get(), &m->photo));
+    }
+    case MessageChatDeletePhoto::ID:
+      return make_tl_object<td_api::messageChatDeletePhoto>();
+    case MessageChatDeleteHistory::ID:
+      return make_tl_object<td_api::messageUnsupported>();
+    case MessageChatAddUsers::ID: {
+      const MessageChatAddUsers *m = static_cast<const MessageChatAddUsers *>(content);
+      return make_tl_object<td_api::messageChatAddMembers>(td_->contacts_manager_->get_user_ids_object(m->user_ids));
+    }
+    case MessageChatJoinedByLink::ID:
+      return make_tl_object<td_api::messageChatJoinByLink>();
+    case MessageChatDeleteUser::ID: {
+      const MessageChatDeleteUser *m = static_cast<const MessageChatDeleteUser *>(content);
+      return make_tl_object<td_api::messageChatDeleteMember>(
+          td_->contacts_manager_->get_user_id_object(m->user_id, "messageChatDeleteMember"));
+    }
+    case MessageChatMigrateTo::ID: {
+      const MessageChatMigrateTo *m = static_cast<const MessageChatMigrateTo *>(content);
+      return make_tl_object<td_api::messageChatUpgradeTo>(
+          td_->contacts_manager_->get_supergroup_id_object(m->migrated_to_channel_id, "messageChatUpgradeTo"));
+    }
+    case MessageChannelCreate::ID: {
+      const MessageChannelCreate *m = static_cast<const MessageChannelCreate *>(content);
+      return make_tl_object<td_api::messageSupergroupChatCreate>(m->title);
+    }
+    case MessageChannelMigrateFrom::ID: {
+      const MessageChannelMigrateFrom *m = static_cast<const MessageChannelMigrateFrom *>(content);
+      return make_tl_object<td_api::messageChatUpgradeFrom>(
+          m->title,
+          td_->contacts_manager_->get_basic_group_id_object(m->migrated_from_chat_id, "messageChatUpgradeFrom"));
+    }
+    case MessagePinMessage::ID: {
+      const MessagePinMessage *m = static_cast<const MessagePinMessage *>(content);
+      return make_tl_object<td_api::messagePinMessage>(m->message_id.get());
+    }
+    case MessageGameScore::ID: {
+      const MessageGameScore *m = static_cast<const MessageGameScore *>(content);
+      return make_tl_object<td_api::messageGameScore>(m->game_message_id.get(), m->game_id, m->score);
+    }
+    case MessageScreenshotTaken::ID:
+      return make_tl_object<td_api::messageScreenshotTaken>();
+    case MessageChatSetTtl::ID: {
+      const MessageChatSetTtl *m = static_cast<const MessageChatSetTtl *>(content);
+      return make_tl_object<td_api::messageChatSetTtl>(m->ttl);
+    }
+    case MessageCall::ID: {
+      const MessageCall *m = static_cast<const MessageCall *>(content);
+      return make_tl_object<td_api::messageCall>(get_call_discard_reason_object(m->discard_reason), m->duration);
+    }
+    case MessagePaymentSuccessful::ID: {
+      const MessagePaymentSuccessful *m = static_cast<const MessagePaymentSuccessful *>(content);
+      if (td_->auth_manager_->is_bot()) {
+        return make_tl_object<td_api::messagePaymentSuccessfulBot>(
+            m->invoice_message_id.get(), m->currency, m->total_amount, m->invoice_payload, m->shipping_option_id,
+            get_order_info_object(m->order_info), m->telegram_payment_charge_id, m->provider_payment_charge_id);
+      } else {
+        return make_tl_object<td_api::messagePaymentSuccessful>(m->invoice_message_id.get(), m->currency,
+                                                                m->total_amount);
+      }
+    }
+    case MessageContactRegistered::ID:
+      return make_tl_object<td_api::messageContactRegistered>();
+    case MessageExpiredPhoto::ID:
+      return make_tl_object<td_api::messageExpiredPhoto>();
+    case MessageExpiredVideo::ID:
+      return make_tl_object<td_api::messageExpiredVideo>();
+    case MessageCustomServiceAction::ID: {
+      const MessageCustomServiceAction *m = static_cast<const MessageCustomServiceAction *>(content);
+      return make_tl_object<td_api::messageCustomServiceAction>(m->message);
+    }
+    case MessageWebsiteConnected::ID: {
+      const MessageWebsiteConnected *m = static_cast<const MessageWebsiteConnected *>(content);
+      return make_tl_object<td_api::messageWebsiteConnected>(m->domain_name);
+    }
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+  UNREACHABLE();
+  return nullptr;
+}
+
+MessageId MessagesManager::get_message_id(const tl_object_ptr<telegram_api::Message> &message_ptr) {
+  int32 constructor_id = message_ptr->get_id();
+  switch (constructor_id) {
+    case telegram_api::messageEmpty::ID: {
+      auto message = static_cast<const telegram_api::messageEmpty *>(message_ptr.get());
+      return MessageId(ServerMessageId(message->id_));
+    }
+    case telegram_api::message::ID: {
+      auto message = static_cast<const telegram_api::message *>(message_ptr.get());
+      return MessageId(ServerMessageId(message->id_));
+    }
+    case telegram_api::messageService::ID: {
+      auto message = static_cast<const telegram_api::messageService *>(message_ptr.get());
+      return MessageId(ServerMessageId(message->id_));
+    }
+    default:
+      UNREACHABLE();
+      return MessageId();
+  }
+}
+
+DialogId MessagesManager::get_message_dialog_id(const tl_object_ptr<telegram_api::Message> &message_ptr) const {
+  return get_full_message_id(message_ptr).get_dialog_id();
+}
+
+FullMessageId MessagesManager::get_full_message_id(const tl_object_ptr<telegram_api::Message> &message_ptr) const {
+  int32 constructor_id = message_ptr->get_id();
+  DialogId dialog_id;
+  MessageId message_id;
+  UserId sender_user_id;
+  switch (constructor_id) {
+    case telegram_api::messageEmpty::ID: {
+      auto message = static_cast<const telegram_api::messageEmpty *>(message_ptr.get());
+      LOG(INFO) << "Receive MessageEmpty";
+      message_id = MessageId(ServerMessageId(message->id_));
+      break;
+    }
+    case telegram_api::message::ID: {
+      auto message = static_cast<const telegram_api::message *>(message_ptr.get());
+      dialog_id = DialogId(message->to_id_);
+      message_id = MessageId(ServerMessageId(message->id_));
+      if (message->flags_ & MESSAGE_FLAG_HAS_FROM_ID) {
+        sender_user_id = UserId(message->from_id_);
+      }
+      break;
+    }
+    case telegram_api::messageService::ID: {
+      auto message = static_cast<const telegram_api::messageService *>(message_ptr.get());
+      dialog_id = DialogId(message->to_id_);
+      message_id = MessageId(ServerMessageId(message->id_));
+      if (message->flags_ & MESSAGE_FLAG_HAS_FROM_ID) {
+        sender_user_id = UserId(message->from_id_);
+      }
+      break;
+    }
+    default:
+      UNREACHABLE();
+      break;
+  }
+
+  UserId my_id = td_->contacts_manager_->get_my_id("get_full_message_id");
+  DialogId my_dialog_id = DialogId(my_id);
+  if (dialog_id == my_dialog_id) {
+    LOG_IF(ERROR, !sender_user_id.is_valid()) << "Receive invalid " << sender_user_id;
+    dialog_id = DialogId(sender_user_id);
+  }
+  return {dialog_id, message_id};
+}
+
+int32 MessagesManager::get_message_date(const tl_object_ptr<telegram_api::Message> &message_ptr) {
+  int32 constructor_id = message_ptr->get_id();
+  switch (constructor_id) {
+    case telegram_api::messageEmpty::ID:
+      return 0;
+    case telegram_api::message::ID: {
+      auto message = static_cast<const telegram_api::message *>(message_ptr.get());
+      return message->date_;
+    }
+    case telegram_api::messageService::ID: {
+      auto message = static_cast<const telegram_api::messageService *>(message_ptr.get());
+      return message->date_;
+    }
+    default:
+      UNREACHABLE();
+      return 0;
+  }
+}
+
+void MessagesManager::ttl_read_history_inbox(DialogId dialog_id, MessageId from_message_id, MessageId till_message_id,
+                                             double timestamp) {
+  auto *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+  auto now = Time::now();
+  for (auto it = MessagesIterator(d, from_message_id); *it && (*it)->message_id.get() >= till_message_id.get(); --it) {
+    auto *message = *it;
+    if (!message->is_outgoing && !message->message_id.is_yet_unsent()) {
+      ttl_on_view(d, message, timestamp, now);
+    }
+  }
+}
+void MessagesManager::ttl_read_history_outbox(DialogId dialog_id, MessageId from_message_id, MessageId till_message_id,
+                                              double timestamp) {
+  auto *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+  auto now = Time::now();
+  for (auto it = MessagesIterator(d, from_message_id); *it && (*it)->message_id.get() >= till_message_id.get(); --it) {
+    auto *message = *it;
+    if (message->is_outgoing && !message->message_id.is_yet_unsent()) {
+      ttl_on_view(d, message, timestamp, now);
+    }
+  }
+}
+
+void MessagesManager::ttl_on_view(const Dialog *d, Message *message, double view_date, double now) {
+  if (message->ttl > 0 && message->ttl_expires_at == 0 && !message->is_content_secret) {
+    message->ttl_expires_at = message->ttl + view_date;
+    ttl_register_message(d->dialog_id, message, now);
+    on_message_changed(d, message, "ttl_on_view");
+  }
+}
+
+bool MessagesManager::ttl_on_open(Dialog *d, Message *message, double now, bool is_local_read) {
+  if (message->ttl > 0 && message->ttl_expires_at == 0) {
+    if (!is_local_read && d->dialog_id.get_type() != DialogType::SecretChat) {
+      on_message_ttl_expired(d, message);
+    } else {
+      message->ttl_expires_at = message->ttl + now;
+      ttl_register_message(d->dialog_id, message, now);
+    }
+    return true;
+  }
+  return false;
+}
+
+void MessagesManager::ttl_register_message(DialogId dialog_id, const Message *message, double now) {
+  if (message->ttl_expires_at == 0) {
+    return;
+  }
+  auto it_flag = ttl_nodes_.insert(TtlNode(dialog_id, message->message_id));
+  CHECK(it_flag.second);
+  auto it = it_flag.first;
+
+  ttl_heap_.insert(message->ttl_expires_at, it->as_heap_node());
+  ttl_update_timeout(now);
+}
+
+void MessagesManager::ttl_unregister_message(DialogId dialog_id, const Message *message, double now) {
+  if (message->ttl_expires_at == 0) {
+    return;
+  }
+
+  TtlNode ttl_node(dialog_id, message->message_id);
+  auto it = ttl_nodes_.find(ttl_node);
+  CHECK(it != ttl_nodes_.end());
+  auto *heap_node = it->as_heap_node();
+  if (heap_node->in_heap()) {
+    ttl_heap_.erase(heap_node);
+  }
+  ttl_nodes_.erase(it);
+  ttl_update_timeout(now);
+}
+
+void MessagesManager::ttl_loop(double now) {
+  std::unordered_map<DialogId, std::vector<MessageId>, DialogIdHash> to_delete;
+  while (!ttl_heap_.empty() && ttl_heap_.top_key() < now) {
+    auto full_message_id = TtlNode::from_heap_node(ttl_heap_.pop())->full_message_id;
+    auto dialog_id = full_message_id.get_dialog_id();
+    if (dialog_id.get_type() == DialogType::SecretChat) {
+      to_delete[dialog_id].push_back(full_message_id.get_message_id());
+    } else {
+      auto d = get_dialog(dialog_id);
+      CHECK(d != nullptr);
+      auto m = get_message(d, full_message_id.get_message_id());
+      CHECK(m != nullptr);
+      on_message_ttl_expired(d, m);
+      on_message_changed(d, m, "ttl_loop");
+    }
+  }
+  for (auto &it : to_delete) {
+    delete_dialog_messages_from_updates(it.first, it.second);
+  }
+  ttl_update_timeout(now);
+}
+
+void MessagesManager::ttl_update_timeout(double now) {
+  if (ttl_heap_.empty()) {
+    if (!ttl_slot_.empty()) {
+      ttl_slot_.cancel_timeout();
+    }
+    return;
+  }
+  ttl_slot_.set_event(EventCreator::yield(actor_id()));
+  ttl_slot_.set_timeout_in(ttl_heap_.top_key() - now);
+}
+
+void MessagesManager::on_message_ttl_expired(Dialog *d, Message *message) {
+  CHECK(d != nullptr);
+  CHECK(message != nullptr);
+  CHECK(message->ttl > 0);
+  CHECK(d->dialog_id.get_type() != DialogType::SecretChat);
+  ttl_unregister_message(d->dialog_id, message, Time::now());
+  on_message_ttl_expired_impl(d, message);
+  send_update_message_content(d->dialog_id, message->message_id, message->content.get(), message->date,
+                              message->is_content_secret, "on_message_ttl_expired");
+}
+
+void MessagesManager::on_message_ttl_expired_impl(Dialog *d, Message *message) {
+  CHECK(d != nullptr);
+  CHECK(message != nullptr);
+  CHECK(message->ttl > 0);
+  CHECK(d->dialog_id.get_type() != DialogType::SecretChat);
+  delete_message_files(message);
+  switch (message->content->get_id()) {
+    case MessagePhoto::ID:
+      message->content = make_unique<MessageExpiredPhoto>();
+      break;
+    case MessageVideo::ID:
+      message->content = make_unique<MessageExpiredVideo>();
+      break;
+    default:
+      UNREACHABLE();
+  }
+  message->ttl = 0;
+  message->ttl_expires_at = 0;
+  if (message->reply_markup != nullptr) {
+    if (message->reply_markup->type != ReplyMarkup::Type::InlineKeyboard) {
+      if (!td_->auth_manager_->is_bot()) {
+        if (d->reply_markup_message_id == message->message_id) {
+          set_dialog_reply_markup(d, MessageId());
+        }
+      }
+      message->had_reply_markup = true;
+    }
+    message->reply_markup = nullptr;
+  }
+  update_message_contains_unread_mention(d, message, false, "on_message_ttl_expired_impl");
+  message->contains_mention = false;
+  message->reply_to_message_id = MessageId();
+  message->is_content_secret = false;
+}
+
+void MessagesManager::loop() {
+  auto token = get_link_token();
+  if (token == YieldType::TtlDb) {
+    ttl_db_loop(G()->server_time());
+  } else {
+    ttl_loop(Time::now());
+  }
+}
+
+void MessagesManager::tear_down() {
+  parent_.reset();
+}
+
+void MessagesManager::start_up() {
+  always_wait_for_mailbox();
+
+  if (G()->parameters().use_message_db) {
+    ttl_db_loop_start(G()->server_time());
+  }
+  load_calls_db_state();
+
+  vector<NotificationSettingsScope> scopes{NOTIFICATION_SETTINGS_FOR_PRIVATE_CHATS,
+                                           NOTIFICATION_SETTINGS_FOR_GROUP_CHATS, NOTIFICATION_SETTINGS_FOR_ALL_CHATS};
+  for (auto scope : scopes) {
+    auto notification_settings_string =
+        G()->td_db()->get_binlog_pmc()->get(get_notification_settings_scope_database_key(scope));
+    if (!notification_settings_string.empty()) {
+      NotificationSettings notification_settings;
+      log_event_parse(notification_settings, notification_settings_string).ensure();
+      if (!notification_settings.is_synchronized) {
+        continue;
+      }
+
+      NotificationSettings *current_settings = get_notification_settings(scope, true);
+      CHECK(current_settings != nullptr);
+      update_notification_settings(scope, current_settings, notification_settings);
+    }
+  }
+
+  /*
+  FI LE *f = std::f open("error.txt", "r");
+  if (f != nullptr) {
+    DialogId dialog_id(ChannelId(123456));
+    force_create_dialog(dialog_id, "test");
+    Dialog *d = get_dialog(dialog_id);
+    CHECK(d != nullptr);
+
+    delete_all_dialog_messages(d, true, false);
+
+    d->last_new_message_id = MessageId();
+    d->last_read_inbox_message_id = MessageId();
+    d->last_read_outbox_message_id = MessageId();
+    d->is_last_read_inbox_message_id_inited = false;
+    d->is_last_read_outbox_message_id_inited = false;
+
+    struct MessageBasicInfo {
+      MessageId message_id;
+      bool have_previous;
+      bool have_next;
+    };
+    vector<MessageBasicInfo> messages_info;
+    std::function<void(Message *m)> get_messages_info = [&](Message *m) {
+      if (m == nullptr) {
+        return;
+      }
+      get_messages_info(m->left.get());
+      messages_info.push_back(MessageBasicInfo{m->message_id, m->have_previous, m->have_next});
+      get_messages_info(m->right.get());
+    };
+
+    char buf[1280];
+    while (std::f gets(buf, sizeof(buf), f) != nullptr) {
+      Slice log_string(buf, std::strlen(buf));
+      Slice op = log_string.substr(0, log_string.find(' '));
+      if (op != "MessageOpAdd" && op != "MessageOpDelete") {
+        LOG(ERROR) << "Unsupported op " << op;
+        continue;
+      }
+      log_string.remove_prefix(log_string.find(' ') + 1);
+
+      if (!begins_with(log_string, "at ")) {
+        LOG(ERROR) << "Date expected, found " << log_string;
+        continue;
+      }
+      log_string.remove_prefix(3);
+      auto date_slice = log_string.substr(0, log_string.find(' '));
+      log_string.remove_prefix(date_slice.size());
+
+      bool is_server = false;
+      if (begins_with(log_string, " server message ")) {
+        log_string.remove_prefix(16);
+        is_server = true;
+      } else if (begins_with(log_string, " yet unsent message ")) {
+        log_string.remove_prefix(20);
+      } else if (begins_with(log_string, " local message ")) {
+        log_string.remove_prefix(15);
+      } else {
+        LOG(ERROR) << "Message id expected, found " << log_string;
+        continue;
+      }
+
+      auto server_message_id = to_integer<int32>(log_string);
+      auto add = 0;
+      if (!is_server) {
+        log_string.remove_prefix(log_string.find('.') + 1);
+        add = to_integer<int32>(log_string);
+      }
+      log_string.remove_prefix(log_string.find(' ') + 1);
+
+      auto message_id = MessageId((static_cast<int64>(server_message_id) << MessageId::SERVER_ID_SHIFT) + add);
+
+      int32 content_type = to_integer<int32>(log_string);
+      log_string.remove_prefix(log_string.find(' ') + 1);
+
+      auto read_bool = [](Slice &str) {
+        if (begins_with(str, "true ")) {
+          str.remove_prefix(5);
+          return true;
+        }
+        if (begins_with(str, "false ")) {
+          str.remove_prefix(6);
+          return false;
+        }
+        LOG(ERROR) << "Bool expected, found " << str;
+        return false;
+      };
+
+      bool from_update = read_bool(log_string);
+      bool have_previous = read_bool(log_string);
+      bool have_next = read_bool(log_string);
+
+      CHECK(content_type != MessageChatDeleteHistory::ID);  // not supported
+      if (op == "MessageOpAdd") {
+        auto m = make_unique<Message>();
+        m->random_y = get_random_y(message_id);
+        m->message_id = message_id;
+        m->date = G()->unix_time();
+        m->content = make_unique<MessageText>(FormattedText{"text", vector<MessageEntity>()}, WebPageId());
+
+        m->have_previous = have_previous;
+        m->have_next = have_next;
+
+        bool need_update = false;
+        bool need_update_dialog_pos = false;
+        if (add_message_to_dialog(dialog_id, std::move(m), from_update, &need_update, &need_update_dialog_pos,
+                                  "Unknown source") == nullptr) {
+          LOG(ERROR) << "Can't add message " << message_id;
+        }
+      } else {
+        bool need_update_dialog_pos = false;
+        auto m = delete_message(d, message_id, true, &need_update_dialog_pos, "Unknown source");
+        CHECK(m != nullptr);
+      }
+
+      messages_info.clear();
+      get_messages_info(d->messages.get());
+
+      for (size_t i = 0; i + 1 < messages_info.size(); i++) {
+        if (messages_info[i].have_next != messages_info[i + 1].have_previous) {
+          LOG(ERROR) << messages_info[i].message_id << " has have_next = " << messages_info[i].have_next << ", but "
+                     << messages_info[i + 1].message_id
+                     << " has have_previous = " << messages_info[i + 1].have_previous;
+        }
+      }
+      if (!messages_info.empty()) {
+        if (messages_info.back().have_next != false) {
+          LOG(ERROR) << messages_info.back().message_id << " has have_next = true, but there is no next message";
+        }
+        if (messages_info[0].have_previous != false) {
+          LOG(ERROR) << messages_info[0].message_id << " has have_previous = true, but there is no previous message";
+        }
+      }
+    }
+
+    messages_info.clear();
+    get_messages_info(d->messages.get());
+    for (auto &info : messages_info) {
+      bool need_update_dialog_pos = false;
+      auto m = delete_message(d, info.message_id, true, &need_update_dialog_pos, "Unknown source");
+      CHECK(m != nullptr);
+    }
+
+    std::f close(f);
+  }
+  */
+}
+
+void MessagesManager::ttl_db_loop_start(double server_now) {
+  ttl_db_expire_from_ = 0;
+  ttl_db_expire_till_ = static_cast<int32>(server_now) + 15 /* 15 seconds */;
+  ttl_db_has_query_ = false;
+
+  ttl_db_loop(server_now);
+}
+
+void MessagesManager::ttl_db_loop(double server_now) {
+  LOG(INFO) << "ttl_db: loop " << tag("expire_from", ttl_db_expire_from_) << tag("expire_till", ttl_db_expire_till_)
+            << tag("has_query", ttl_db_has_query_);
+  if (ttl_db_has_query_) {
+    return;
+  }
+
+  auto now = static_cast<int32>(server_now);
+
+  if (ttl_db_expire_till_ < 0) {
+    LOG(INFO) << "ttl_db: finished";
+    return;
+  }
+
+  if (now < ttl_db_expire_from_) {
+    ttl_db_slot_.set_event(EventCreator::yield(actor_shared(this, YieldType::TtlDb)));
+    auto wakeup_in = ttl_db_expire_from_ - server_now;
+    ttl_db_slot_.set_timeout_in(wakeup_in);
+    LOG(INFO) << "ttl_db: " << tag("wakeup in", wakeup_in);
+    return;
+  }
+
+  ttl_db_has_query_ = true;
+  int32 limit = 50;
+  LOG(INFO) << "ttl_db: send query " << tag("expire_from", ttl_db_expire_from_)
+            << tag("expire_till", ttl_db_expire_till_) << tag("limit", limit);
+  G()->td_db()->get_messages_db_async()->get_expiring_messages(
+      ttl_db_expire_from_, ttl_db_expire_till_, limit,
+      PromiseCreator::lambda(
+          [actor_id = actor_id(this)](Result<std::pair<std::vector<std::pair<DialogId, BufferSlice>>, int32>> result) {
+            send_closure(actor_id, &MessagesManager::ttl_db_on_result, std::move(result), false);
+          }));
+}
+
+void MessagesManager::ttl_db_on_result(Result<std::pair<std::vector<std::pair<DialogId, BufferSlice>>, int32>> r_result,
+                                       bool dummy) {
+  auto result = r_result.move_as_ok();
+  ttl_db_has_query_ = false;
+  ttl_db_expire_from_ = ttl_db_expire_till_;
+  ttl_db_expire_till_ = result.second;
+
+  LOG(INFO) << "ttl_db: query result " << tag("new expire_till", ttl_db_expire_till_)
+            << tag("got messages", result.first.size());
+  for (auto &dialog_message : result.first) {
+    on_get_message_from_database(dialog_message.first, get_dialog_force(dialog_message.first), dialog_message.second);
+  }
+  ttl_db_loop(G()->server_time());
+}
+
+void MessagesManager::on_send_secret_message_error(int64 random_id, Status error, Promise<> promise) {
+  promise.set_value(Unit());  // TODO: set after error is saved
+  LOG(INFO) << "Receive error for SecretChatsManager::send_message: " << error;
+
+  auto it = being_sent_messages_.find(random_id);
+  if (it != being_sent_messages_.end()) {
+    auto full_message_id = it->second;
+    auto *message = get_message(full_message_id);
+    if (message != nullptr) {
+      auto file_id = get_message_content_file_id(message->content.get());
+      if (file_id.is_valid()) {
+        if (G()->close_flag() && G()->parameters().use_message_db) {
+          // do not send error, message will be re-sent
+          return;
+        }
+        if (begins_with(error.message(), "FILE_PART_") && ends_with(error.message(), "_MISSING")) {
+          on_send_message_file_part_missing(random_id, to_integer<int32>(error.message().substr(10)));
+          return;
+        }
+
+        if (error.code() != 429 && error.code() < 500 && !G()->close_flag()) {
+          td_->file_manager_->delete_partial_remote_location(file_id);
+        }
+      }
+    }
+  }
+
+  on_send_message_fail(random_id, std::move(error));
+}
+
+void MessagesManager::on_send_secret_message_success(int64 random_id, MessageId message_id, int32 date,
+                                                     tl_object_ptr<telegram_api::EncryptedFile> file_ptr,
+                                                     Promise<> promise) {
+  promise.set_value(Unit());  // TODO: set after message is saved
+
+  FileId new_file_id;
+  if (file_ptr != nullptr && file_ptr->get_id() == telegram_api::encryptedFile::ID) {
+    auto file = move_tl_object_as<telegram_api::encryptedFile>(file_ptr);
+    if (!DcId::is_valid(file->dc_id_)) {
+      LOG(ERROR) << "Wrong dc_id = " << file->dc_id_ << " in file " << to_string(file);
+    } else {
+      DialogId owner_dialog_id;
+      auto it = being_sent_messages_.find(random_id);
+      if (it != being_sent_messages_.end()) {
+        owner_dialog_id = it->second.get_dialog_id();
+      }
+
+      new_file_id = td_->file_manager_->register_remote(
+          FullRemoteFileLocation(FileType::Encrypted, file->id_, file->access_hash_, DcId::internal(file->dc_id_)),
+          FileLocationSource::FromServer, owner_dialog_id, 0, 0, "");
+    }
+  }
+
+  on_send_message_success(random_id, message_id, date, new_file_id, "process send_secret_message_success");
+}
+
+void MessagesManager::delete_secret_messages(SecretChatId secret_chat_id, std::vector<int64> random_ids,
+                                             Promise<> promise) {
+  promise.set_value(Unit());  // TODO: set after event is saved
+  DialogId dialog_id(secret_chat_id);
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    LOG(ERROR) << "Ignore delete secret messages in unknown " << dialog_id;
+    return;
+  }
+
+  vector<MessageId> to_delete_message_ids;
+  for (auto &random_id : random_ids) {
+    auto message_id = get_message_id_by_random_id(d, random_id);
+    if (!message_id.is_valid()) {
+      continue;
+    }
+    const Message *m = get_message(d, message_id);
+    CHECK(m != nullptr);
+    if (!is_service_message_content(m->content->get_id())) {
+      to_delete_message_ids.push_back(message_id);
+    }
+  }
+  delete_dialog_messages_from_updates(dialog_id, to_delete_message_ids);
+}
+
+void MessagesManager::delete_secret_chat_history(SecretChatId secret_chat_id, MessageId last_message_id,
+                                                 Promise<> promise) {
+  promise.set_value(Unit());  // TODO: set after event is saved
+  auto dialog_id = DialogId(secret_chat_id);
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    LOG(ERROR) << "Ignore delete secret chat history in unknown " << dialog_id;
+    return;
+  }
+
+  // TODO: probably last_message_id is not needed
+  delete_all_dialog_messages(d, false, true);
+}
+
+void MessagesManager::read_secret_chat_outbox(SecretChatId secret_chat_id, int32 up_to_date, int32 read_date) {
+  if (!secret_chat_id.is_valid()) {
+    LOG(ERROR) << "Receive read secret chat outbox in the invalid " << secret_chat_id;
+    return;
+  }
+  auto dialog_id = DialogId(secret_chat_id);
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return;
+  }
+  // TODO: protect with logevent
+  suffix_load_till_date(
+      d, up_to_date,
+      PromiseCreator::lambda([actor_id = actor_id(this), dialog_id, up_to_date, read_date](Result<Unit> result) {
+        send_closure(actor_id, &MessagesManager::read_secret_chat_outbox_inner, dialog_id, up_to_date, read_date);
+      }));
+}
+
+void MessagesManager::read_secret_chat_outbox_inner(DialogId dialog_id, int32 up_to_date, int32 read_date) {
+  Dialog *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+
+  auto end = MessagesConstIterator(d, MessageId::max());
+  while (*end && (*end)->date > up_to_date) {
+    --end;
+  }
+  if (!*end) {
+    LOG(INFO) << "Ignore read_secret_chat_outbox in " << dialog_id << " at " << up_to_date
+              << ": no messages with such date are known";
+    return;
+  }
+  auto max_message_id = (*end)->message_id;
+  read_history_outbox(dialog_id, max_message_id, read_date);
+}
+
+void MessagesManager::open_secret_message(SecretChatId secret_chat_id, int64 random_id, Promise<> promise) {
+  promise.set_value(Unit());  // TODO: set after event is saved
+  DialogId dialog_id(secret_chat_id);
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    LOG(ERROR) << "Ignore opening secret chat message in unknown " << dialog_id;
+    return;
+  }
+
+  auto message_id = get_message_id_by_random_id(d, random_id);
+  if (!message_id.is_valid()) {
+    return;
+  }
+  Message *m = get_message(d, message_id);
+  CHECK(m != nullptr);
+  if (message_id.is_yet_unsent() || !m->is_outgoing) {
+    LOG(ERROR) << "Peer has opened wrong " << message_id << " in " << dialog_id;
+    return;
+  }
+
+  read_message_content(d, m, false, "open_secret_message");
+}
+
+void MessagesManager::on_get_secret_message(SecretChatId secret_chat_id, UserId user_id, MessageId message_id,
+                                            int32 date, tl_object_ptr<telegram_api::encryptedFile> file,
+                                            tl_object_ptr<secret_api::decryptedMessage> message, Promise<> promise) {
+  LOG(DEBUG) << "On get " << to_string(message);
+  CHECK(message != nullptr);
+  CHECK(secret_chat_id.is_valid());
+  CHECK(user_id.is_valid());
+  CHECK(message_id.is_valid());
+  CHECK(date > 0);
+
+  auto pending_secret_message = make_unique<PendingSecretMessage>();
+  pending_secret_message->success_promise = std::move(promise);
+  MessageInfo &message_info = pending_secret_message->message_info;
+  message_info.dialog_id = DialogId(secret_chat_id);
+  message_info.message_id = message_id;
+  message_info.sender_user_id = user_id;
+  message_info.date = date;
+  message_info.random_id = message->random_id_;
+  message_info.ttl = message->ttl_;
+
+  Dialog *d = get_dialog_force(message_info.dialog_id);
+  if (d == nullptr) {
+    LOG(ERROR) << "Ignore secret message in unknown " << message_info.dialog_id;
+    pending_secret_message->success_promise.set_error(Status::Error(500, "Chat not found"));
+    return;
+  }
+
+  pending_secret_message->load_data_multipromise.add_promise(Auto());
+  auto lock_promise = pending_secret_message->load_data_multipromise.get_promise();
+
+  int32 flags = MESSAGE_FLAG_HAS_UNREAD_CONTENT | MESSAGE_FLAG_HAS_FROM_ID;
+  if ((message->flags_ & secret_api::decryptedMessage::REPLY_TO_RANDOM_ID_MASK) != 0) {
+    message_info.reply_to_message_id =
+        get_message_id_by_random_id(get_dialog(message_info.dialog_id), message->reply_to_random_id_);
+    if (message_info.reply_to_message_id.is_valid()) {
+      flags |= MESSAGE_FLAG_IS_REPLY;
+    }
+  }
+  if ((message->flags_ & secret_api::decryptedMessage::ENTITIES_MASK) != 0) {
+    flags |= MESSAGE_FLAG_HAS_ENTITIES;
+  }
+  if ((message->flags_ & secret_api::decryptedMessage::MEDIA_MASK) != 0) {
+    flags |= MESSAGE_FLAG_HAS_MEDIA;
+  }
+
+  if (!clean_input_string(message->via_bot_name_)) {
+    LOG(WARNING) << "Receive invalid bot username " << message->via_bot_name_;
+    message->via_bot_name_.clear();
+  }
+  if ((message->flags_ & secret_api::decryptedMessage::VIA_BOT_NAME_MASK) != 0 && !message->via_bot_name_.empty()) {
+    pending_secret_message->load_data_multipromise.add_promise(
+        PromiseCreator::lambda([this, via_bot_name = message->via_bot_name_, &flags = message_info.flags,
+                                &via_bot_user_id = message_info.via_bot_user_id](Unit) mutable {
+          auto dialog_id = resolve_dialog_username(via_bot_name);
+          if (dialog_id.is_valid() && dialog_id.get_type() == DialogType::User) {
+            flags |= MESSAGE_FLAG_IS_SENT_VIA_BOT;
+            via_bot_user_id = dialog_id.get_user_id();
+          }
+        }));
+    search_public_dialog(message->via_bot_name_, false, pending_secret_message->load_data_multipromise.get_promise());
+  }
+  if ((message->flags_ & secret_api::decryptedMessage::GROUPED_ID_MASK) != 0 && message->grouped_id_ != 0) {
+    message_info.media_album_id = message->grouped_id_;
+    flags |= MESSAGE_FLAG_HAS_MEDIA_ALBUM_ID;
+  }
+
+  message_info.flags = flags;
+  message_info.content = get_secret_message_content(
+      std::move(message->message_), std::move(file), std::move(message->media_), std::move(message->entities_),
+      message_info.dialog_id, pending_secret_message->load_data_multipromise);
+
+  add_secret_message(std::move(pending_secret_message), std::move(lock_promise));
+}
+
+void MessagesManager::on_secret_chat_screenshot_taken(SecretChatId secret_chat_id, UserId user_id, MessageId message_id,
+                                                      int32 date, int64 random_id, Promise<> promise) {
+  LOG(DEBUG) << "On screenshot taken in " << secret_chat_id;
+  CHECK(secret_chat_id.is_valid());
+  CHECK(user_id.is_valid());
+  CHECK(message_id.is_valid());
+  CHECK(date > 0);
+
+  auto pending_secret_message = make_unique<PendingSecretMessage>();
+  pending_secret_message->success_promise = std::move(promise);
+  MessageInfo &message_info = pending_secret_message->message_info;
+  message_info.dialog_id = DialogId(secret_chat_id);
+  message_info.message_id = message_id;
+  message_info.sender_user_id = user_id;
+  message_info.date = date;
+  message_info.random_id = random_id;
+  message_info.flags = MESSAGE_FLAG_HAS_FROM_ID;
+  message_info.content = make_unique<MessageScreenshotTaken>();
+
+  Dialog *d = get_dialog_force(message_info.dialog_id);
+  if (d == nullptr) {
+    LOG(ERROR) << "Ignore secret message in unknown " << message_info.dialog_id;
+    pending_secret_message->success_promise.set_error(Status::Error(500, "Chat not found"));
+    return;
+  }
+
+  add_secret_message(std::move(pending_secret_message));
+}
+
+void MessagesManager::on_secret_chat_ttl_changed(SecretChatId secret_chat_id, UserId user_id, MessageId message_id,
+                                                 int32 date, int32 ttl, int64 random_id, Promise<> promise) {
+  LOG(DEBUG) << "On ttl set in " << secret_chat_id << " to " << ttl;
+  CHECK(secret_chat_id.is_valid());
+  CHECK(user_id.is_valid());
+  CHECK(message_id.is_valid());
+  CHECK(date > 0);
+  if (ttl < 0) {
+    LOG(WARNING) << "Receive wrong ttl = " << ttl;
+    promise.set_value(Unit());
+    return;
+  }
+
+  auto pending_secret_message = make_unique<PendingSecretMessage>();
+  pending_secret_message->success_promise = std::move(promise);
+  MessageInfo &message_info = pending_secret_message->message_info;
+  message_info.dialog_id = DialogId(secret_chat_id);
+  message_info.message_id = message_id;
+  message_info.sender_user_id = user_id;
+  message_info.date = date;
+  message_info.random_id = random_id;
+  message_info.flags = MESSAGE_FLAG_HAS_FROM_ID;
+  message_info.content = make_unique<MessageChatSetTtl>(ttl);
+
+  Dialog *d = get_dialog_force(message_info.dialog_id);
+  if (d == nullptr) {
+    LOG(ERROR) << "Ignore secret message in unknown " << message_info.dialog_id;
+    pending_secret_message->success_promise.set_error(Status::Error(500, "Chat not found"));
+    return;
+  }
+
+  add_secret_message(std::move(pending_secret_message));
+}
+
+void MessagesManager::add_secret_message(unique_ptr<PendingSecretMessage> pending_secret_message,
+                                         Promise<Unit> lock_promise) {
+  auto &multipromise = pending_secret_message->load_data_multipromise;
+  multipromise.set_ignore_errors(true);
+  int64 token = pending_secret_messages_.add(std::move(pending_secret_message));
+
+  multipromise.add_promise(PromiseCreator::lambda([token, actor_id = actor_id(this),
+                                                   this](Result<Unit> result) mutable {
+    if (result.is_ok()) {  // if we aren't closing
+      this->pending_secret_messages_.finish(token, [actor_id](unique_ptr<PendingSecretMessage> pending_secret_message) {
+        send_closure_later(actor_id, &MessagesManager::finish_add_secret_message, std::move(pending_secret_message));
+      });
+    }
+  }));
+
+  if (!lock_promise) {
+    lock_promise = multipromise.get_promise();
+  }
+  lock_promise.set_value(Unit());
+}
+
+void MessagesManager::finish_add_secret_message(unique_ptr<PendingSecretMessage> pending_secret_message) {
+  auto d = get_dialog(pending_secret_message->message_info.dialog_id);
+  CHECK(d != nullptr);
+  auto random_id = pending_secret_message->message_info.random_id;
+  auto message_id = get_message_id_by_random_id(d, random_id);
+  if (message_id.is_valid()) {
+    if (message_id != pending_secret_message->message_info.message_id) {
+      LOG(WARNING) << "Ignore duplicate " << pending_secret_message->message_info.message_id
+                   << " received earlier with " << message_id << " and random_id " << random_id;
+    }
+  } else {
+    on_get_message(std::move(pending_secret_message->message_info), true, false, true, true,
+                   "finish add secret message");
+  }
+  pending_secret_message->success_promise.set_value(Unit());  // TODO: set after message is saved
+}
+
+void MessagesManager::fix_message_info_dialog_id(MessageInfo &message_info) const {
+  if (message_info.dialog_id != DialogId(td_->contacts_manager_->get_my_id("fix_message_info_dialog_id"))) {
+    return;
+  }
+
+  UserId sender_user_id = message_info.sender_user_id;
+  if (!sender_user_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid sender user id in private chat";
+    return;
+  }
+
+  message_info.dialog_id = DialogId(sender_user_id);
+  LOG_IF(ERROR, (message_info.flags & MESSAGE_FLAG_IS_OUT) != 0)
+      << "Receive message out flag for incoming " << message_info.message_id << " in " << message_info.dialog_id;
+}
+
+MessagesManager::MessageInfo MessagesManager::parse_telegram_api_message(
+    tl_object_ptr<telegram_api::Message> message_ptr, const char *source) const {
+  LOG(DEBUG) << "Receive from " << source << " " << to_string(message_ptr);
+  CHECK(message_ptr != nullptr) << source;
+  int32 constructor_id = message_ptr->get_id();
+
+  MessageInfo message_info;
+  switch (constructor_id) {
+    case telegram_api::messageEmpty::ID:
+      break;
+    case telegram_api::message::ID: {
+      auto message = move_tl_object_as<telegram_api::message>(message_ptr);
+
+      message_info.dialog_id = DialogId(message->to_id_);
+      message_info.message_id = MessageId(ServerMessageId(message->id_));
+      if (message->flags_ & MESSAGE_FLAG_HAS_FROM_ID) {
+        message_info.sender_user_id = UserId(message->from_id_);
+      }
+      message_info.date = message->date_;
+      message_info.forward_header = std::move(message->fwd_from_);
+      message_info.reply_to_message_id = MessageId(ServerMessageId(
+          message->flags_ & MESSAGE_FLAG_IS_REPLY ? message->reply_to_msg_id_ : 0));  // TODO zero init in fetch
+      if (message->flags_ & MESSAGE_FLAG_IS_SENT_VIA_BOT) {
+        message_info.via_bot_user_id = UserId(message->via_bot_id_);
+        if (!message_info.via_bot_user_id.is_valid()) {
+          LOG(ERROR) << "Receive invalid " << message_info.via_bot_user_id << " from " << source;
+          message_info.via_bot_user_id = UserId();
+        }
+      }
+      if (message->flags_ & MESSAGE_FLAG_HAS_VIEWS) {
+        message_info.views = message->views_;
+      }
+      if (message->flags_ & MESSAGE_FLAG_HAS_EDIT_DATE) {
+        message_info.edit_date = message->edit_date_;
+      }
+      if (message->flags_ & MESSAGE_FLAG_HAS_MEDIA_ALBUM_ID) {
+        message_info.media_album_id = message->grouped_id_;
+      }
+      message_info.flags = message->flags_;
+      fix_message_info_dialog_id(message_info);
+      bool is_content_read = (message->flags_ & MESSAGE_FLAG_HAS_UNREAD_CONTENT) == 0;
+      if (is_message_auto_read(message_info.dialog_id, (message->flags_ & MESSAGE_FLAG_IS_OUT) != 0, true)) {
+        is_content_read = true;
+      }
+      message_info.content = get_message_content(
+          get_message_text(std::move(message->message_), std::move(message->entities_),
+                           message_info.forward_header ? message_info.forward_header->date_ : message_info.date),
+          std::move(message->media_), message_info.dialog_id, is_content_read, message_info.via_bot_user_id,
+          &message_info.ttl);
+      message_info.reply_markup =
+          message->flags_ & MESSAGE_FLAG_HAS_REPLY_MARKUP ? std::move(message->reply_markup_) : nullptr;
+      message_info.author_signature = std::move(message->post_author_);
+      break;
+    }
+    case telegram_api::messageService::ID: {
+      auto message = move_tl_object_as<telegram_api::messageService>(message_ptr);
+
+      message_info.dialog_id = DialogId(message->to_id_);
+      message_info.message_id = MessageId(ServerMessageId(message->id_));
+      if (message->flags_ & MESSAGE_FLAG_HAS_FROM_ID) {
+        message_info.sender_user_id = UserId(message->from_id_);
+      }
+      message_info.date = message->date_;
+      message_info.flags = message->flags_;
+      fix_message_info_dialog_id(message_info);
+      MessageId reply_to_message_id = MessageId(ServerMessageId(
+          message->flags_ & MESSAGE_FLAG_IS_REPLY ? message->reply_to_msg_id_ : 0));  // TODO zero init in fetch
+      message_info.content =
+          get_message_action_content(std::move(message->action_), message_info.dialog_id, reply_to_message_id);
+      break;
+    }
+    default:
+      UNREACHABLE();
+      break;
+  }
+  return message_info;
+}
+
+std::pair<DialogId, unique_ptr<MessagesManager::Message>> MessagesManager::create_message(MessageInfo &&message_info,
+                                                                                          bool is_channel_message) {
+  DialogId dialog_id = message_info.dialog_id;
+  MessageId message_id = message_info.message_id;
+  if (!message_id.is_valid() || !dialog_id.is_valid()) {
+    if (message_id != MessageId() || dialog_id != DialogId()) {
+      LOG(ERROR) << "Receive " << message_id << " in " << dialog_id;
+    }
+    return {DialogId(), nullptr};
+  }
+  if (message_id.is_yet_unsent()) {
+    LOG(ERROR) << "Receive " << message_id;
+    return {DialogId(), nullptr};
+  }
+
+  CHECK(message_info.content != nullptr);
+
+  UserId sender_user_id = message_info.sender_user_id;
+  if (!sender_user_id.is_valid()) {
+    if (!is_broadcast_channel(dialog_id)) {
+      LOG(ERROR) << "Invalid " << sender_user_id << " specified to be a sender of the " << message_id << " in "
+                 << dialog_id;
+      return {DialogId(), nullptr};
+    }
+
+    if (sender_user_id != UserId()) {
+      LOG(ERROR) << "Receive invalid " << sender_user_id;
+      sender_user_id = UserId();
+    }
+  }
+
+  auto dialog_type = dialog_id.get_type();
+  LOG_IF(ERROR, is_channel_message && dialog_type != DialogType::Channel)
+      << "is_channel_message is true for message received in the " << dialog_id;
+
+  int32 flags = message_info.flags;
+  if (flags & ~(MESSAGE_FLAG_IS_OUT | MESSAGE_FLAG_IS_FORWARDED | MESSAGE_FLAG_IS_REPLY | MESSAGE_FLAG_HAS_MENTION |
+                MESSAGE_FLAG_HAS_UNREAD_CONTENT | MESSAGE_FLAG_HAS_REPLY_MARKUP | MESSAGE_FLAG_HAS_ENTITIES |
+                MESSAGE_FLAG_HAS_FROM_ID | MESSAGE_FLAG_HAS_MEDIA | MESSAGE_FLAG_HAS_VIEWS |
+                MESSAGE_FLAG_IS_SENT_VIA_BOT | MESSAGE_FLAG_IS_SILENT | MESSAGE_FLAG_IS_POST |
+                MESSAGE_FLAG_HAS_EDIT_DATE | MESSAGE_FLAG_HAS_AUTHOR_SIGNATURE | MESSAGE_FLAG_HAS_MEDIA_ALBUM_ID)) {
+    LOG(ERROR) << "Unsupported message flags = " << flags << " received";
+  }
+
+  bool is_outgoing = (flags & MESSAGE_FLAG_IS_OUT) != 0;
+  bool is_silent = (flags & MESSAGE_FLAG_IS_SILENT) != 0;
+  bool is_channel_post = (flags & MESSAGE_FLAG_IS_POST) != 0;
+
+  UserId my_id = td_->contacts_manager_->get_my_id("create_message");
+  DialogId my_dialog_id = DialogId(my_id);
+  if (dialog_id == my_dialog_id) {
+    // dialog_id should be already fixed
+    CHECK(sender_user_id == my_id);
+  }
+
+  if (sender_user_id.is_valid() && (sender_user_id == my_id && dialog_id != my_dialog_id) != is_outgoing) {
+    //    if (content->get_id() != MessageChatAddUser::ID) {  // TODO: we have wrong flags for invites via links
+    LOG(ERROR) << "Receive wrong message out flag: me is " << my_id << ", message is from " << sender_user_id
+               << ", flags = " << flags << " for " << message_id << " in " << dialog_id;
+    //    }
+  }
+
+  MessageId reply_to_message_id = message_info.reply_to_message_id;
+  if (reply_to_message_id != MessageId() &&
+      (!reply_to_message_id.is_valid() || reply_to_message_id.get() >= message_id.get())) {
+    LOG(ERROR) << "Receive reply to wrong " << reply_to_message_id << " in " << message_id;
+    reply_to_message_id = MessageId();
+  }
+
+  UserId via_bot_user_id = message_info.via_bot_user_id;
+  if (!via_bot_user_id.is_valid()) {
+    via_bot_user_id = UserId();
+  }
+
+  int32 date = message_info.date;
+  if (date <= 0) {
+    LOG(ERROR) << "Wrong date = " << date << " received in " << message_id << " in " << dialog_id;
+    date = 1;
+  }
+
+  int32 edit_date = message_info.edit_date;
+  if (edit_date < 0) {
+    LOG(ERROR) << "Wrong edit_date = " << edit_date << " received in " << message_id << " in " << dialog_id;
+    edit_date = 0;
+  }
+
+  int32 ttl = message_info.ttl;
+  bool is_content_secret =
+      is_secret_message_content(ttl, message_info.content->get_id());  // should be calculated before TTL is adjusted
+  if (ttl < 0) {
+    LOG(ERROR) << "Wrong ttl = " << ttl << " received in " << message_id << " in " << dialog_id;
+    ttl = 0;
+  } else if (ttl > 0) {
+    ttl = max(ttl, get_message_content_duration(message_info.content.get()) + 1);
+  }
+
+  int32 views = message_info.views;
+  if (views < 0) {
+    LOG(ERROR) << "Wrong views = " << views << " received in " << message_id << " in " << dialog_id;
+    views = 0;
+  }
+
+  LOG(INFO) << "Receive " << message_id << " in " << dialog_id << " from " << sender_user_id;
+
+  auto message = make_unique<Message>();
+  message->random_y = get_random_y(message_id);
+  message->message_id = message_id;
+  message->sender_user_id = sender_user_id;
+  message->date = date;
+  message->ttl = ttl;
+  message->edit_date = edit_date;
+  message->random_id = message_info.random_id;
+  message->forward_info = get_message_forward_info(std::move(message_info.forward_header));
+  message->reply_to_message_id = reply_to_message_id;
+  message->via_bot_user_id = via_bot_user_id;
+  message->author_signature = std::move(message_info.author_signature);
+  message->is_outgoing = is_outgoing;
+  message->is_channel_post = is_channel_post;
+  message->contains_mention =
+      !is_outgoing && dialog_type != DialogType::User && (flags & MESSAGE_FLAG_HAS_MENTION) != 0;
+  message->contains_unread_mention =
+      message_id.is_server() && message->contains_mention && (flags & MESSAGE_FLAG_HAS_UNREAD_CONTENT) != 0 &&
+      (dialog_type == DialogType::Chat || (dialog_type == DialogType::Channel && !is_broadcast_channel(dialog_id)));
+  message->disable_notification = is_silent;
+  message->is_content_secret = is_content_secret;
+  message->views = views;
+  message->content = std::move(message_info.content);
+  message->reply_markup = get_reply_markup(std::move(message_info.reply_markup), td_->auth_manager_->is_bot(), false,
+                                           message->contains_mention || dialog_id.get_type() == DialogType::User);
+
+  auto content_id = message->content->get_id();
+  if (content_id == MessageExpiredPhoto::ID || content_id == MessageExpiredVideo::ID) {
+    CHECK(message->ttl == 0);  // ttl is ignored/set to 0 if the message has already been expired
+    if (message->reply_markup != nullptr) {
+      if (message->reply_markup->type != ReplyMarkup::Type::InlineKeyboard) {
+        message->had_reply_markup = true;
+      }
+      message->reply_markup = nullptr;
+    }
+    message->reply_to_message_id = MessageId();
+  }
+
+  if (message_info.media_album_id != 0) {
+    if (!is_allowed_media_group_content(content_id)) {
+      LOG(ERROR) << "Receive media group id " << message_info.media_album_id << " in " << message_id << " from "
+                 << dialog_id << " with content "
+                 << oneline(to_string(
+                        get_message_content_object(message->content.get(), message->date, is_content_secret)));
+    } else {
+      message->media_album_id = message_info.media_album_id;
+    }
+  }
+
+  return {dialog_id, std::move(message)};
+}
+
+FullMessageId MessagesManager::on_get_message(tl_object_ptr<telegram_api::Message> message_ptr, bool from_update,
+                                              bool is_channel_message, bool have_previous, bool have_next,
+                                              const char *source) {
+  return on_get_message(parse_telegram_api_message(std::move(message_ptr), source), from_update, is_channel_message,
+                        have_previous, have_next, source);
+}
+
+FullMessageId MessagesManager::on_get_message(MessageInfo &&message_info, bool from_update, bool is_channel_message,
+                                              bool have_previous, bool have_next, const char *source) {
+  DialogId dialog_id;
+  unique_ptr<Message> new_message;
+  std::tie(dialog_id, new_message) = create_message(std::move(message_info), is_channel_message);
+  if (new_message == nullptr) {
+    return FullMessageId();
+  }
+  MessageId message_id = new_message->message_id;
+
+  DialogId my_dialog_id = DialogId(td_->contacts_manager_->get_my_id("on_get_message"));
+
+  new_message->have_previous = have_previous;
+  new_message->have_next = have_next;
+
+  bool need_update = from_update;
+  bool need_update_dialog_pos = false;
+
+  FullMessageId full_message_id(dialog_id, message_id);
+  auto it = update_message_ids_.find(full_message_id);
+  if (it != update_message_ids_.end()) {
+    Dialog *d = get_dialog(dialog_id);
+    CHECK(d != nullptr);
+
+    if (!from_update) {
+      LOG_IF(ERROR, message_id.get() <= d->last_new_message_id.get())
+          << "New " << message_id << " has id less than last_new_message_id = " << d->last_new_message_id;
+      LOG(ERROR) << "Ignore " << it->second << " received not through update from " << source << ": "
+                 << oneline(to_string(get_message_object(dialog_id, new_message.get())));  // TODO move to INFO
+      dump_debug_message_op(d, 3);                                                         // TODO remove
+      if (dialog_id.get_type() == DialogType::Channel && have_input_peer(dialog_id, AccessRights::Read)) {
+        channel_get_difference_retry_timeout_.add_timeout_in(dialog_id.get(), 0.001);
+      }
+      return FullMessageId();
+    }
+
+    MessageId old_message_id = it->second;
+
+    update_message_ids_.erase(it);
+
+    if (!new_message->is_outgoing && dialog_id != my_dialog_id) {
+      // sent message is not from me
+      LOG(ERROR) << "Sent in " << dialog_id << " " << message_id << " is sent by " << new_message->sender_user_id;
+      return FullMessageId();
+    }
+
+    unique_ptr<Message> old_message =
+        delete_message(d, old_message_id, false, &need_update_dialog_pos, "add sent message");
+    if (old_message == nullptr) {
+      // message has already been deleted by the user or sent to inaccessible channel
+      // don't need to send update to the user, because the message has already been deleted
+      LOG(INFO) << "Delete already deleted sent " << new_message->message_id << " from server";
+      delete_messages_from_server(dialog_id, {new_message->message_id}, true, 0, Auto());
+      return FullMessageId();
+    }
+
+    need_update = false;
+
+    new_message->message_id = old_message_id;
+    new_message->random_y = get_random_y(new_message->message_id);
+    new_message->have_previous = false;
+    new_message->have_next = false;
+    update_message(d, old_message, std::move(new_message), true, &need_update_dialog_pos);
+    new_message = std::move(old_message);
+
+    new_message->message_id = message_id;
+    new_message->random_y = get_random_y(new_message->message_id);
+    send_update_message_send_succeeded(d, old_message_id, new_message.get());
+
+    try_add_active_live_location(dialog_id, new_message.get());
+
+    new_message->have_previous = true;
+    new_message->have_next = true;
+  }
+
+  Message *m = add_message_to_dialog(dialog_id, std::move(new_message), from_update, &need_update,
+                                     &need_update_dialog_pos, source);
+  Dialog *d = get_dialog(dialog_id);
+  if (m == nullptr) {
+    if (need_update_dialog_pos && d != nullptr) {
+      send_update_chat_last_message(d, "on_get_message");
+    }
+
+    return FullMessageId();
+  }
+
+  CHECK(d != nullptr);
+
+  auto pcc_it = pending_created_dialogs_.find(dialog_id);
+  if (from_update && pcc_it != pending_created_dialogs_.end()) {
+    pcc_it->second.set_value(Unit());
+
+    pending_created_dialogs_.erase(pcc_it);
+  }
+
+  if (need_update) {
+    send_update_new_message(d, m);
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    auto p = delete_message(d, message_id, false, &need_update_dialog_pos, "get a message in inaccessible chat");
+    CHECK(p.get() == m);
+    // CHECK(d->messages == nullptr);
+    send_update_delete_messages(dialog_id, {message_id.get()}, false, false);
+    // don't need to update dialog pos
+    return FullMessageId();
+  }
+
+  if (need_update_dialog_pos) {
+    send_update_chat_last_message(d, "on_get_message");
+  }
+
+  if (need_update && m->reply_markup != nullptr && m->reply_markup->type != ReplyMarkup::Type::InlineKeyboard &&
+      m->reply_markup->is_personal && !td_->auth_manager_->is_bot()) {
+    set_dialog_reply_markup(d, message_id);
+  }
+
+  return FullMessageId(dialog_id, message_id);
+}
+
+void MessagesManager::set_dialog_last_message_id(Dialog *d, MessageId last_message_id, const char *source) {
+  LOG(INFO) << "Set " << d->dialog_id << " last message to " << last_message_id << " from " << source;
+  d->last_message_id = last_message_id;
+
+  if (last_message_id.is_valid() && d->delete_last_message_date != 0) {
+    d->delete_last_message_date = 0;
+    d->deleted_last_message_id = MessageId();
+    d->is_last_message_deleted_locally = false;
+    on_dialog_updated(d->dialog_id, "update_delete_last_message_date");
+  }
+}
+
+void MessagesManager::set_dialog_first_database_message_id(Dialog *d, MessageId first_database_message_id,
+                                                           const char *source) {
+  LOG(INFO) << "Set " << d->dialog_id << " first database message to " << first_database_message_id << " from "
+            << source;
+  d->first_database_message_id = first_database_message_id;
+}
+
+void MessagesManager::set_dialog_last_database_message_id(Dialog *d, MessageId last_database_message_id,
+                                                          const char *source) {
+  LOG(INFO) << "Set " << d->dialog_id << " last database message to " << last_database_message_id << " from " << source;
+  d->last_database_message_id = last_database_message_id;
+}
+
+void MessagesManager::set_dialog_last_new_message_id(Dialog *d, MessageId last_new_message_id, const char *source) {
+  CHECK(last_new_message_id.get() > d->last_new_message_id.get());
+  CHECK(d->dialog_id.get_type() == DialogType::SecretChat || last_new_message_id.is_server());
+  if (!d->last_new_message_id.is_valid()) {
+    delete_all_dialog_messages_from_database(d->dialog_id, MessageId::max(), "set_dialog_last_new_message_id");
+    set_dialog_first_database_message_id(d, MessageId(), "set_dialog_last_new_message_id");
+    set_dialog_last_database_message_id(d, MessageId(), "set_dialog_last_new_message_id");
+    if (d->dialog_id.get_type() != DialogType::SecretChat) {
+      d->have_full_history = false;
+    }
+    for (auto &first_message_id : d->first_database_message_id_by_index) {
+      first_message_id = last_new_message_id;
+    }
+
+    MessagesConstIterator it(d, MessageId::max());
+    vector<MessageId> to_delete_message_ids;
+    while (*it != nullptr) {
+      auto message_id = (*it)->message_id;
+      if (message_id.get() <= last_new_message_id.get()) {
+        break;
+      }
+      if (!message_id.is_yet_unsent()) {
+        to_delete_message_ids.push_back(message_id);
+      }
+      --it;
+    }
+    if (!to_delete_message_ids.empty()) {
+      LOG(ERROR) << "Delete " << format::as_array(to_delete_message_ids) << " because of received last new "
+                 << last_new_message_id << " in " << d->dialog_id;
+
+      vector<int64> deleted_message_ids;
+      bool need_update_dialog_pos = false;
+      for (auto message_id : to_delete_message_ids) {
+        if (delete_message(d, message_id, false, &need_update_dialog_pos, "set_dialog_last_new_message_id") !=
+            nullptr) {
+          deleted_message_ids.push_back(message_id.get());
+        }
+      }
+      if (need_update_dialog_pos) {
+        send_update_chat_last_message(d, "set_dialog_last_new_message_id");
+      }
+      send_update_delete_messages(d->dialog_id, std::move(deleted_message_ids), false, false);
+    }
+
+    auto last_new_message = get_message(d, last_new_message_id);
+    if (last_new_message != nullptr) {
+      add_message_to_database(d, last_new_message, "set_dialog_last_new_message_id");
+      set_dialog_first_database_message_id(d, last_new_message_id, "set_dialog_last_new_message_id");
+      set_dialog_last_database_message_id(d, last_new_message_id, "set_dialog_last_new_message_id");
+      try_restore_dialog_reply_markup(d, last_new_message);
+    }
+  }
+
+  LOG(INFO) << "Set " << d->dialog_id << " last new message to " << last_new_message_id << " from " << source;
+  d->last_new_message_id = last_new_message_id;
+  on_dialog_updated(d->dialog_id, source);
+}
+
+void MessagesManager::set_dialog_last_clear_history_date(Dialog *d, int32 date, MessageId last_clear_history_message_id,
+                                                         const char *source) {
+  LOG(INFO) << "Set " << d->dialog_id << " last clear history date to " << date << " of "
+            << last_clear_history_message_id << " from " << source;
+  if (d->last_clear_history_message_id.is_valid()) {
+    switch (d->dialog_id.get_type()) {
+      case DialogType::User:
+      case DialogType::Chat:
+        last_clear_history_message_id_to_dialog_id_.erase(d->last_clear_history_message_id);
+        break;
+      case DialogType::Channel:
+      case DialogType::SecretChat:
+        // nothing to do
+        break;
+      case DialogType::None:
+      default:
+        UNREACHABLE();
+    }
+  }
+
+  d->last_clear_history_date = date;
+  d->last_clear_history_message_id = last_clear_history_message_id;
+
+  if (d->last_clear_history_message_id.is_valid()) {
+    switch (d->dialog_id.get_type()) {
+      case DialogType::User:
+      case DialogType::Chat:
+        last_clear_history_message_id_to_dialog_id_[d->last_clear_history_message_id] = d->dialog_id;
+        break;
+      case DialogType::Channel:
+      case DialogType::SecretChat:
+        // nothing to do
+        break;
+      case DialogType::None:
+      default:
+        UNREACHABLE();
+    }
+  }
+}
+
+void MessagesManager::set_dialog_is_empty(Dialog *d, const char *source) {
+  LOG(INFO) << "Set " << d->dialog_id << " is_empty to true from " << source;
+  d->is_empty = true;
+
+  if (d->delete_last_message_date != 0) {
+    if (d->is_last_message_deleted_locally && d->last_clear_history_date == 0) {
+      set_dialog_last_clear_history_date(d, d->delete_last_message_date, d->deleted_last_message_id,
+                                         "set_dialog_is_empty");
+    }
+    d->delete_last_message_date = 0;
+    d->deleted_last_message_id = MessageId();
+    d->is_last_message_deleted_locally = false;
+
+    on_dialog_updated(d->dialog_id, "set_dialog_is_empty");
+  }
+
+  update_dialog_pos(d, false, source);
+}
+
+void MessagesManager::set_dialog_is_pinned(DialogId dialog_id, bool is_pinned) {
+  Dialog *d = get_dialog(dialog_id);
+  set_dialog_is_pinned(d, is_pinned);
+  update_dialog_pos(d, false, "set_dialog_is_pinned");
+}
+
+void MessagesManager::set_dialog_is_pinned(Dialog *d, bool is_pinned) {
+  CHECK(d != nullptr);
+  bool was_pinned = d->pinned_order != DEFAULT_ORDER;
+  d->pinned_order = is_pinned ? get_next_pinned_dialog_order() : DEFAULT_ORDER;
+  on_dialog_updated(d->dialog_id, "set_dialog_is_pinned");
+
+  if (is_pinned != was_pinned) {
+    LOG(INFO) << "Set " << d->dialog_id << " is pinned to " << is_pinned;
+    CHECK(d == get_dialog(d->dialog_id)) << "Wrong " << d->dialog_id << " in set_dialog_is_pinned";
+    update_dialog_pos(d, false, "set_dialog_is_pinned", false);
+    DialogDate dialog_date(d->order, d->dialog_id);
+    send_closure(G()->td(), &Td::send_update,
+                 make_tl_object<td_api::updateChatIsPinned>(d->dialog_id.get(), is_pinned,
+                                                            dialog_date <= last_dialog_date_ ? d->order : 0));
+  }
+}
+
+void MessagesManager::set_dialog_reply_markup(Dialog *d, MessageId message_id) {
+  if (d->reply_markup_message_id != message_id) {
+    on_dialog_updated(d->dialog_id, "set_dialog_reply_markup");
+  }
+
+  d->need_restore_reply_markup = false;
+
+  if (d->reply_markup_message_id.is_valid() || message_id.is_valid()) {
+    CHECK(d == get_dialog(d->dialog_id)) << "Wrong " << d->dialog_id << " in set_dialog_reply_markup";
+    d->reply_markup_message_id = message_id;
+    send_closure(G()->td(), &Td::send_update,
+                 make_tl_object<td_api::updateChatReplyMarkup>(d->dialog_id.get(), message_id.get()));
+  }
+}
+
+void MessagesManager::try_restore_dialog_reply_markup(Dialog *d, const Message *m) {
+  if (!d->need_restore_reply_markup || td_->auth_manager_->is_bot()) {
+    return;
+  }
+
+  if (m->had_reply_markup) {
+    LOG(INFO) << "Restore deleted reply markup in " << d->dialog_id;
+    set_dialog_reply_markup(d, MessageId());
+  } else if (m->reply_markup != nullptr && m->reply_markup->type != ReplyMarkup::Type::InlineKeyboard &&
+             m->reply_markup->is_personal) {
+    LOG(INFO) << "Restore reply markup in " << d->dialog_id << " to " << m->message_id;
+    set_dialog_reply_markup(d, m->message_id);
+  }
+}
+
+// TODO this function needs to be merged with on_send_message_success
+void MessagesManager::on_update_sent_text_message(int64 random_id,
+                                                  tl_object_ptr<telegram_api::MessageMedia> message_media,
+                                                  vector<tl_object_ptr<telegram_api::MessageEntity>> &&entities) {
+  CHECK(message_media != nullptr);
+  int32 message_media_id = message_media->get_id();
+  LOG_IF(ERROR, message_media_id != telegram_api::messageMediaWebPage::ID &&
+                    message_media_id != telegram_api::messageMediaEmpty::ID)
+      << "Receive non web-page media for text message: " << oneline(to_string(message_media));
+
+  auto it = being_sent_messages_.find(random_id);
+  if (it == being_sent_messages_.end()) {
+    // result of sending message has already been received through getDifference
+    return;
+  }
+
+  auto dialog_id = it->second.get_dialog_id();
+  auto m = get_message_force(it->second);
+  if (m == nullptr) {
+    // message has already been deleted
+    return;
+  }
+
+  if (m->content->get_id() != MessageText::ID) {
+    LOG(ERROR) << "Text message content has been already changed to " << m->content->get_id();
+    return;
+  }
+  auto message_text = static_cast<const MessageText *>(m->content.get());
+
+  auto new_content = get_message_content(
+      get_message_text(message_text->text.text, std::move(entities), m->forward_info ? m->forward_info->date : m->date),
+      std::move(message_media), dialog_id, true /*likely ignored*/, UserId() /*likely ignored*/, nullptr /*ignored*/);
+  if (new_content->get_id() != MessageText::ID) {
+    LOG(ERROR) << "Text message content has changed to " << new_content->get_id();
+    return;
+  }
+  auto new_message_text = static_cast<const MessageText *>(new_content.get());
+
+  bool need_update = false;
+  bool is_content_changed = false;
+
+  if (message_text->text.entities != new_message_text->text.entities) {
+    is_content_changed = true;
+    need_update = true;
+  }
+  if (message_text->web_page_id != new_message_text->web_page_id) {
+    LOG(INFO) << "Old: " << message_text->web_page_id << ", new: " << new_message_text->web_page_id;
+    is_content_changed = true;
+    need_update |= td_->web_pages_manager_->have_web_page(message_text->web_page_id) ||
+                   td_->web_pages_manager_->have_web_page(new_message_text->web_page_id);
+  }
+
+  if (is_content_changed) {
+    m->content = std::move(new_content);
+    m->is_content_secret = is_secret_message_content(m->ttl, m->content->get_id());
+  }
+  if (need_update) {
+    send_update_message_content(dialog_id, m->message_id, m->content.get(), m->date, m->is_content_secret,
+                                "on_update_sent_text_message");
+  }
+}
+
+void MessagesManager::on_update_message_web_page(FullMessageId full_message_id, bool have_web_page) {
+  waiting_for_web_page_messages_.erase(full_message_id);
+  auto dialog_id = full_message_id.get_dialog_id();
+  Dialog *d = get_dialog(dialog_id);
+  if (d == nullptr) {
+    LOG(INFO) << "Can't find " << dialog_id;
+    // dialog can be not yet added
+    return;
+  }
+  auto message_id = full_message_id.get_message_id();
+  Message *message = get_message(d, message_id);
+  if (message == nullptr) {
+    // message can be already deleted
+    return;
+  }
+  CHECK(message->date > 0);
+  auto content_type = message->content->get_id();
+  CHECK(content_type == MessageText::ID);
+  auto content = static_cast<MessageText *>(message->content.get());
+  if (!content->web_page_id.is_valid()) {
+    // webpage has already been received as empty
+    LOG_IF(ERROR, have_web_page) << "Receive earlier not received web page";
+    return;
+  }
+
+  if (!have_web_page) {
+    content->web_page_id = WebPageId();
+    // don't need to send an update
+
+    on_message_changed(d, message, "on_update_message_web_page");
+    return;
+  }
+
+  send_update_message_content(dialog_id, message_id, content, message->date, message->is_content_secret,
+                              "on_update_message_web_page");
+}
+
+void MessagesManager::on_get_dialogs(vector<tl_object_ptr<telegram_api::dialog>> &&dialogs, int32 total_count,
+                                     vector<tl_object_ptr<telegram_api::Message>> &&messages, Promise<Unit> &&promise) {
+  if (td_->updates_manager_->running_get_difference()) {
+    LOG(INFO) << "Postpone result of getDialogs";
+    pending_on_get_dialogs_.push_back(
+        PendingOnGetDialogs{std::move(dialogs), total_count, std::move(messages), std::move(promise)});
+    return;
+  }
+  bool from_dialog_list = total_count >= 0;
+  bool from_get_dialog = total_count == -1;
+  bool from_pinned_dialog_list = total_count == -2;
+
+  if (from_get_dialog && dialogs.size() == 1) {
+    DialogId dialog_id(dialogs[0]->peer_);
+    if (running_get_channel_difference(dialog_id)) {
+      LOG(INFO) << "Postpone result of channels getDialogs for " << dialog_id;
+      pending_channel_on_get_dialogs_.emplace(
+          dialog_id, PendingOnGetDialogs{std::move(dialogs), total_count, std::move(messages), std::move(promise)});
+      return;
+    }
+  }
+
+  LOG(INFO) << "Receive " << dialogs.size() << " dialogs out of " << total_count << " in result of GetDialogsQuery";
+  std::unordered_map<FullMessageId, DialogDate, FullMessageIdHash> full_message_id_to_dialog_date;
+  std::unordered_map<FullMessageId, tl_object_ptr<telegram_api::Message>, FullMessageIdHash> full_message_id_to_message;
+  for (auto &message : messages) {
+    auto full_message_id = get_full_message_id(message);
+    if (from_dialog_list) {
+      auto message_date = get_message_date(message);
+      int64 order = get_dialog_order(full_message_id.get_message_id(), message_date);
+      full_message_id_to_dialog_date.emplace(full_message_id, DialogDate(order, full_message_id.get_dialog_id()));
+    }
+    full_message_id_to_message[full_message_id] = std::move(message);
+  }
+
+  DialogDate max_dialog_date = MIN_DIALOG_DATE;
+  for (auto &dialog : dialogs) {
+    //    LOG(INFO) << to_string(dialog);
+    DialogId dialog_id(dialog->peer_);
+    bool has_pts = (dialog->flags_ & DIALOG_FLAG_HAS_PTS) != 0;
+
+    if (!dialog_id.is_valid()) {
+      LOG(ERROR) << "Receive wrong " << dialog_id;
+      return promise.set_error(Status::Error(500, "Wrong query result returned: receive wrong chat identifier"));
+    }
+    switch (dialog_id.get_type()) {
+      case DialogType::User:
+      case DialogType::Chat:
+        if (has_pts) {
+          LOG(ERROR) << "Receive user or group " << dialog_id << " with pts";
+          return promise.set_error(
+              Status::Error(500, "Wrong query result returned: receive user or basic group chat with pts"));
+        }
+        break;
+      case DialogType::Channel:
+        if (!has_pts) {
+          LOG(ERROR) << "Receive channel " << dialog_id << "without pts";
+          return promise.set_error(
+              Status::Error(500, "Wrong query result returned: receive supergroup chat without pts"));
+        }
+        break;
+      case DialogType::SecretChat:
+      case DialogType::None:
+      default:
+        UNREACHABLE();
+        return promise.set_error(Status::Error(500, "UNREACHABLE"));
+    }
+
+    if (from_dialog_list) {
+      MessageId last_message_id(ServerMessageId(dialog->top_message_));
+      if (last_message_id.is_valid()) {
+        FullMessageId full_message_id(dialog_id, last_message_id);
+        auto it = full_message_id_to_dialog_date.find(full_message_id);
+        if (it == full_message_id_to_dialog_date.end()) {
+          // can happen for bots, TODO disable getChats for bots
+          LOG(ERROR) << "Last " << last_message_id << " in " << dialog_id << " not found";
+          return promise.set_error(Status::Error(500, "Wrong query result returned: last message not found"));
+        }
+        DialogDate dialog_date = it->second;
+        CHECK(dialog_date.get_dialog_id() == dialog_id);
+
+        if (max_dialog_date < dialog_date) {
+          max_dialog_date = dialog_date;
+        }
+      } else {
+        LOG(ERROR) << "Receive " << last_message_id << " as last chat message";
+        continue;
+      }
+    }
+  }
+
+  if (from_dialog_list) {
+    if (dialogs.empty()) {
+      // if there is no more dialogs on the server
+      max_dialog_date = MAX_DIALOG_DATE;
+    }
+    if (last_server_dialog_date_ < max_dialog_date) {
+      last_server_dialog_date_ = max_dialog_date;
+      update_last_dialog_date();
+    } else {
+      LOG(ERROR) << "Last server dialog date didn't increased";
+    }
+  }
+  if (from_pinned_dialog_list) {
+    max_dialog_date = DialogDate(get_dialog_order(MessageId(), MIN_PINNED_DIALOG_DATE - 1), DialogId());
+    if (last_server_dialog_date_ < max_dialog_date) {
+      last_server_dialog_date_ = max_dialog_date;
+      update_last_dialog_date();
+    }
+  }
+
+  vector<DialogId> added_dialog_ids;
+  for (auto &dialog : dialogs) {
+    MessageId last_message_id(ServerMessageId(dialog->top_message_));
+    if (!last_message_id.is_valid() && from_dialog_list) {
+      // skip dialogs without messages
+      continue;
+    }
+
+    DialogId dialog_id(dialog->peer_);
+    added_dialog_ids.push_back(dialog_id);
+    Dialog *d = get_dialog_force(dialog_id);
+    bool need_update_dialog_pos = false;
+    if (d == nullptr) {
+      d = add_dialog(dialog_id);
+      need_update_dialog_pos = true;
+    } else {
+      LOG(INFO) << "Receive already created " << dialog_id;
+      CHECK(d->dialog_id == dialog_id);
+    }
+    bool is_new = d->last_new_message_id == MessageId();
+
+    on_update_notify_settings(dialog_id.get(), std::move(dialog->notify_settings_));
+
+    if (dialog->unread_count_ < 0) {
+      LOG(ERROR) << "Receive " << dialog->unread_count_ << " as number of unread messages in " << dialog_id;
+      dialog->unread_count_ = 0;
+    }
+    MessageId read_inbox_max_message_id = MessageId(ServerMessageId(dialog->read_inbox_max_id_));
+    if (!read_inbox_max_message_id.is_valid() && read_inbox_max_message_id != MessageId()) {
+      LOG(ERROR) << "Receive " << read_inbox_max_message_id << " as last read inbox message in " << dialog_id;
+      read_inbox_max_message_id = MessageId();
+    }
+    MessageId read_outbox_max_message_id = MessageId(ServerMessageId(dialog->read_outbox_max_id_));
+    if (!read_outbox_max_message_id.is_valid() && read_outbox_max_message_id != MessageId()) {
+      LOG(ERROR) << "Receive " << read_outbox_max_message_id << " as last read outbox message in " << dialog_id;
+      read_outbox_max_message_id = MessageId();
+    }
+    if (dialog->unread_mentions_count_ < 0) {
+      LOG(ERROR) << "Receive " << dialog->unread_mentions_count_ << " as number of unread mention messages in "
+                 << dialog_id;
+      dialog->unread_mentions_count_ = 0;
+    }
+
+    need_update_dialog_pos |= update_dialog_draft_message(
+        d, get_draft_message(td_->contacts_manager_.get(), std::move(dialog->draft_)), true, false);
+    if (is_new) {
+      bool has_pts = (dialog->flags_ & DIALOG_FLAG_HAS_PTS) != 0;
+      if (last_message_id.is_valid()) {
+        FullMessageId full_message_id(dialog_id, last_message_id);
+        auto added_full_message_id = on_get_message(std::move(full_message_id_to_message[full_message_id]), false,
+                                                    has_pts, false, false, "get chats");
+        CHECK(d->last_new_message_id == MessageId());
+        set_dialog_last_new_message_id(d, full_message_id.get_message_id(), "on_get_dialogs");
+        if (d->last_new_message_id.get() > d->last_message_id.get() &&
+            added_full_message_id.get_message_id().is_valid()) {
+          CHECK(added_full_message_id.get_message_id() == d->last_new_message_id);
+          set_dialog_last_message_id(d, d->last_new_message_id, "on_get_dialogs");
+          send_update_chat_last_message(d, "on_get_dialogs");
+        }
+      }
+
+      if (has_pts && !running_get_channel_difference(dialog_id)) {
+        int32 channel_pts = dialog->pts_;
+        LOG_IF(ERROR, channel_pts < d->pts) << "In new " << dialog_id << " pts = " << d->pts
+                                            << ", but pts = " << channel_pts << " received in GetChats";
+        set_channel_pts(d, channel_pts, "get channel");
+      }
+    }
+    bool is_pinned = (dialog->flags_ & DIALOG_FLAG_IS_PINNED) != 0;
+    bool was_pinned = d->pinned_order != DEFAULT_ORDER;
+    if (is_pinned != was_pinned) {
+      set_dialog_is_pinned(d, is_pinned);
+      need_update_dialog_pos = false;
+    }
+
+    if (need_update_dialog_pos) {
+      update_dialog_pos(d, false, "on_get_dialogs");
+    }
+
+    if (!G()->parameters().use_message_db || is_new ||
+        (!d->is_last_read_inbox_message_id_inited && read_inbox_max_message_id.is_valid())) {
+      if (d->server_unread_count != dialog->unread_count_ ||
+          d->last_read_inbox_message_id.get() < read_inbox_max_message_id.get()) {
+        set_dialog_last_read_inbox_message_id(d, read_inbox_max_message_id, dialog->unread_count_,
+                                              d->local_unread_count, true, "on_get_dialogs");
+      }
+    }
+
+    if (!G()->parameters().use_message_db || is_new ||
+        (!d->is_last_read_outbox_message_id_inited && read_outbox_max_message_id.is_valid())) {
+      if (d->last_read_outbox_message_id.get() < read_outbox_max_message_id.get()) {
+        set_dialog_last_read_outbox_message_id(d, read_outbox_max_message_id);
+      }
+    }
+
+    if (!G()->parameters().use_message_db || is_new) {
+      if (d->unread_mention_count != dialog->unread_mentions_count_) {
+        d->unread_mention_count = dialog->unread_mentions_count_;
+        d->message_count_by_index[search_messages_filter_index(SearchMessagesFilter::UnreadMention)] =
+            d->unread_mention_count;
+        send_update_chat_unread_mention_count(d);
+      }
+    }
+  }
+  if (from_pinned_dialog_list) {
+    auto pinned_dialog_ids = remove_secret_chat_dialog_ids(get_pinned_dialogs());
+    std::reverse(pinned_dialog_ids.begin(), pinned_dialog_ids.end());
+    if (pinned_dialog_ids != added_dialog_ids) {
+      LOG(INFO) << "Repair pinned dialogs order from " << format::as_array(pinned_dialog_ids) << " to "
+                << format::as_array(added_dialog_ids);
+
+      std::unordered_set<DialogId, DialogIdHash> old_pinned_dialog_ids(pinned_dialog_ids.begin(),
+                                                                       pinned_dialog_ids.end());
+
+      auto old_it = pinned_dialog_ids.begin();
+      for (auto dialog_id : added_dialog_ids) {
+        old_pinned_dialog_ids.erase(dialog_id);
+        while (old_it < pinned_dialog_ids.end()) {
+          if (*old_it == dialog_id) {
+            break;
+          }
+          old_it++;
+        }
+        if (old_it < pinned_dialog_ids.end()) {
+          // leave dialog where it is
+          continue;
+        }
+        set_dialog_is_pinned(dialog_id, true);
+      }
+      for (auto dialog_id : old_pinned_dialog_ids) {
+        set_dialog_is_pinned(dialog_id, false);
+      }
+    }
+  }
+  promise.set_value(Unit());
+}
+
+constexpr bool MessagesManager::is_debug_message_op_enabled() {
+  return !LOG_IS_STRIPPED(ERROR) && false;
+}
+
+void MessagesManager::dump_debug_message_op(const Dialog *d, int priority) {
+  if (!is_debug_message_op_enabled()) {
+    return;
+  }
+  if (d == nullptr) {
+    LOG(ERROR) << "Chat not found";
+    return;
+  }
+  static int last_dumped_priority = -1;
+  if (priority <= last_dumped_priority) {
+    LOG(ERROR) << "Skip dump " << d->dialog_id;
+    return;
+  }
+  last_dumped_priority = priority;
+
+  for (auto &op : d->debug_message_op) {
+    switch (op.type) {
+      case Dialog::MessageOp::Add: {
+        LOG(ERROR) << "MessageOpAdd at " << op.date << " " << op.message_id << " " << op.content_type << " "
+                   << op.from_update << " " << op.have_previous << " " << op.have_next << " " << op.source;
+        break;
+      }
+      case Dialog::MessageOp::SetPts: {
+        LOG(ERROR) << "MessageOpSetPts at " << op.date << " " << op.content_type << " " << op.source;
+        break;
+      }
+      case Dialog::MessageOp::Delete: {
+        LOG(ERROR) << "MessageOpDelete at " << op.date << " " << op.message_id << " " << op.content_type << " "
+                   << op.from_update << " " << op.have_previous << " " << op.have_next << " " << op.source;
+        break;
+      }
+      case Dialog::MessageOp::DeleteAll: {
+        LOG(ERROR) << "MessageOpDeleteAll at " << op.date << " " << op.from_update;
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+  }
+}
+
+bool MessagesManager::is_message_unload_enabled() const {
+  return G()->parameters().use_message_db || td_->auth_manager_->is_bot();
+}
+
+bool MessagesManager::can_unload_message(const Dialog *d, const Message *m) const {
+  // don't want to unload messages from opened dialogs
+  // don't want to unload messages to which there are replies in yet unsent messages
+  // don't want to unload messages with pending web pages
+  // can't unload from memory last dialog, last database messages, yet unsent messages and active live locations
+  FullMessageId full_message_id{d->dialog_id, m->message_id};
+  return !d->is_opened && m->message_id != d->last_message_id && m->message_id != d->last_database_message_id &&
+         !m->message_id.is_yet_unsent() && active_live_location_full_message_ids_.count(full_message_id) == 0 &&
+         replied_by_yet_unsent_messages_.count(full_message_id) == 0 &&
+         waiting_for_web_page_messages_.count(full_message_id) == 0;
+}
+
+void MessagesManager::unload_message(Dialog *d, MessageId message_id) {
+  bool need_update_dialog_pos = false;
+  auto m = do_delete_message(d, message_id, false, true, &need_update_dialog_pos, "unload_message");
+  CHECK(!need_update_dialog_pos);
+}
+
+unique_ptr<MessagesManager::Message> MessagesManager::delete_message(Dialog *d, MessageId message_id,
+                                                                     bool is_permanently_deleted,
+                                                                     bool *need_update_dialog_pos, const char *source) {
+  return do_delete_message(d, message_id, is_permanently_deleted, false, need_update_dialog_pos, source);
+}
+
+// DO NOT FORGET TO ADD ALL CHANGES OF THIS FUNCTION AS WELL TO do_delete_all_dialog_messages
+unique_ptr<MessagesManager::Message> MessagesManager::do_delete_message(Dialog *d, MessageId message_id,
+                                                                        bool is_permanently_deleted,
+                                                                        bool only_from_memory,
+                                                                        bool *need_update_dialog_pos,
+                                                                        const char *source) {
+  if (!message_id.is_valid()) {
+    LOG(ERROR) << "Trying to delete " << message_id << " in " << d->dialog_id << " from " << source;
+    return nullptr;
+  }
+
+  FullMessageId full_message_id(d->dialog_id, message_id);
+  unique_ptr<Message> *v = find_message(&d->messages, message_id);
+  if (*v == nullptr) {
+    LOG(INFO) << message_id << " is not found in " << d->dialog_id << " to be deleted from " << source;
+    if (only_from_memory) {
+      return nullptr;
+    }
+
+    if (get_message_force(d, message_id) == nullptr) {
+      // currently there may be a race between add_message_to_database and get_message_force,
+      // so delete a message from database just in case
+      delete_message_from_database(d, message_id, nullptr, is_permanently_deleted);
+
+      if (is_permanently_deleted && d->last_clear_history_message_id == message_id) {
+        set_dialog_last_clear_history_date(d, 0, MessageId(), "do_delete_message");
+        on_dialog_updated(d->dialog_id, "forget last_clear_history_date from do_delete_message");
+        *need_update_dialog_pos = true;
+      }
+
+      /*
+      can't do this because the message may be never received in the dialog, unread count will became negative
+      // if last_read_inbox_message_id is not known, we can't be sure whether unread_count should be decreased or not
+      if (message_id.is_valid() && !message_id.is_yet_unsent() && d->is_last_read_inbox_message_id_inited &&
+          message_id.get() > d->last_read_inbox_message_id.get() && !td_->auth_manager_->is_bot()) {
+        int32 server_unread_count = d->server_unread_count;
+        int32 local_unread_count = d->local_unread_count;
+        int32 &unread_count = message_id.is_server() ? server_unread_count : local_unread_count;
+        if (unread_count == 0) {
+          LOG(ERROR) << "Unread count became negative in " << d->dialog_id << " after deletion of " << message_id
+                     << ". Last read is " << d->last_read_inbox_message_id;
+          dump_debug_message_op(d, 3);
+        } else {
+          unread_count--;
+          set_dialog_last_read_inbox_message_id(d, MessageId::min(), server_unread_count, local_unread_count, false,
+                                                source);
+        }
+      }
+      */
+      return nullptr;
+    }
+    v = find_message(&d->messages, message_id);
+    CHECK(*v != nullptr);
+  }
+
+  const Message *m = v->get();
+  if (only_from_memory && !can_unload_message(d, m)) {
+    return nullptr;
+  }
+
+  if (is_debug_message_op_enabled()) {
+    d->debug_message_op.emplace_back(Dialog::MessageOp::Delete, m->message_id, m->content->get_id(), false,
+                                     m->have_previous, m->have_next, source);
+  }
+
+  LOG(INFO) << "Deleting " << full_message_id << " with have_previous = " << m->have_previous
+            << " and have_next = " << m->have_next << " from " << source;
+
+  bool need_get_history = false;
+  if (!only_from_memory) {
+    delete_message_from_database(d, message_id, m, is_permanently_deleted);
+
+    delete_active_live_location(d->dialog_id, m);
+
+    if (message_id == d->last_message_id) {
+      MessagesConstIterator it(d, message_id);
+      CHECK(*it == m);
+      if ((*it)->have_previous) {
+        --it;
+        if (*it != nullptr) {
+          set_dialog_last_message_id(d, (*it)->message_id, "do_delete_message");
+        } else {
+          LOG(ERROR) << "have_previous is true, but there is no previous for " << full_message_id << " from " << source;
+          dump_debug_message_op(d);
+          set_dialog_last_message_id(d, MessageId(), "do_delete_message");
+        }
+      } else {
+        need_get_history = true;
+        set_dialog_last_message_id(d, MessageId(), "do_delete_message");
+        d->delete_last_message_date = m->date;
+        d->deleted_last_message_id = message_id;
+        d->is_last_message_deleted_locally = Slice(source) == Slice(DELETE_MESSAGE_USER_REQUEST_SOURCE);
+        on_dialog_updated(d->dialog_id, "do delete last message");
+      }
+      *need_update_dialog_pos = true;
+    }
+
+    if (message_id == d->last_database_message_id) {
+      MessagesConstIterator it(d, message_id);
+      CHECK(*it == m);
+      while ((*it)->have_previous) {
+        --it;
+        if (*it == nullptr || !(*it)->message_id.is_yet_unsent()) {
+          break;
+        }
+      }
+
+      if (*it != nullptr) {
+        if (!(*it)->message_id.is_yet_unsent() && (*it)->message_id != d->last_database_message_id) {
+          set_dialog_last_database_message_id(d, (*it)->message_id, "do_delete_message");
+        } else {
+          need_get_history = true;
+        }
+      } else {
+        LOG(ERROR) << "have_previous is true, but there is no previous";
+        dump_debug_message_op(d);
+      }
+      on_dialog_updated(d->dialog_id, "do delete last database message");
+    }
+    if (d->last_database_message_id.is_valid()) {
+      CHECK(d->first_database_message_id.is_valid());
+    } else {
+      set_dialog_first_database_message_id(d, MessageId(), "do_delete_message");
+    }
+  }
+
+  if (m->have_previous && (only_from_memory || !m->have_next)) {
+    MessagesIterator it(d, message_id);
+    CHECK(*it == m);
+    --it;
+    Message *prev_m = *it;
+    if (prev_m != nullptr) {
+      prev_m->have_next = false;
+    } else {
+      LOG(ERROR) << "have_previous is true, but there is no previous for " << full_message_id << " from " << source;
+      dump_debug_message_op(d);
+    }
+  }
+  if ((*v)->have_next && (only_from_memory || !(*v)->have_previous)) {
+    MessagesIterator it(d, message_id);
+    CHECK(*it == m);
+    ++it;
+    Message *next_m = *it;
+    if (next_m != nullptr) {
+      next_m->have_previous = false;
+    } else {
+      LOG(ERROR) << "have_next is true, but there is no next for " << full_message_id << " from " << source;
+      dump_debug_message_op(d);
+    }
+  }
+
+  unique_ptr<Message> result = std::move(*v);
+  unique_ptr<Message> left = std::move(result->left);
+  unique_ptr<Message> right = std::move(result->right);
+
+  while (left != nullptr || right != nullptr) {
+    if (left == nullptr || (right != nullptr && right->random_y > left->random_y)) {
+      *v = std::move(right);
+      v = &((*v)->left);
+      right = std::move(*v);
+    } else {
+      *v = std::move(left);
+      v = &((*v)->right);
+      left = std::move(*v);
+    }
+  }
+  CHECK(*v == nullptr);
+
+  if (!only_from_memory) {
+    if (message_id.is_yet_unsent()) {
+      cancel_send_message_query(d->dialog_id, result);
+    }
+
+    if (need_get_history && !td_->auth_manager_->is_bot() && have_input_peer(d->dialog_id, AccessRights::Read)) {
+      get_history_from_the_end(d->dialog_id, true, false, Auto());
+    }
+
+    if (d->reply_markup_message_id == message_id) {
+      set_dialog_reply_markup(d, MessageId());
+    }
+    // if last_read_inbox_message_id is not known, we can't be sure whether unread_count should be decreased or not
+    if (!result->is_outgoing && message_id.get() > d->last_read_inbox_message_id.get() &&
+        d->dialog_id != DialogId(td_->contacts_manager_->get_my_id("do_delete_message")) &&
+        d->is_last_read_inbox_message_id_inited && !td_->auth_manager_->is_bot()) {
+      int32 server_unread_count = d->server_unread_count;
+      int32 local_unread_count = d->local_unread_count;
+      int32 &unread_count = message_id.is_server() ? server_unread_count : local_unread_count;
+      if (unread_count == 0) {
+        LOG(ERROR) << "Unread count became negative in " << d->dialog_id << " after deletion of " << message_id
+                   << ". Last read is " << d->last_read_inbox_message_id;
+        dump_debug_message_op(d, 3);
+      } else {
+        unread_count--;
+        set_dialog_last_read_inbox_message_id(d, MessageId::min(), server_unread_count, local_unread_count, false,
+                                              source);
+      }
+    }
+    if (result->contains_unread_mention) {
+      if (d->unread_mention_count == 0) {
+        LOG_IF(ERROR,
+               d->message_count_by_index[search_messages_filter_index(SearchMessagesFilter::UnreadMention)] != -1)
+            << "Unread mention count became negative in " << d->dialog_id << " after deletion of " << message_id;
+      } else {
+        d->unread_mention_count--;
+        d->message_count_by_index[search_messages_filter_index(SearchMessagesFilter::UnreadMention)] =
+            d->unread_mention_count;
+        send_update_chat_unread_mention_count(d);
+      }
+    }
+
+    update_message_count_by_index(d, -1, result.get());
+  }
+
+  switch (d->dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+      message_id_to_dialog_id_.erase(message_id);
+      break;
+    case DialogType::Channel:
+      // nothing to do
+      break;
+    case DialogType::SecretChat:
+      LOG(INFO) << "Delete correspondence random_id " << result->random_id << " to " << message_id << " in "
+                << d->dialog_id;
+      d->random_id_to_message_id.erase(result->random_id);
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+  ttl_unregister_message(d->dialog_id, result.get(), Time::now());
+
+  return result;
+}
+
+void MessagesManager::do_delete_all_dialog_messages(Dialog *d, unique_ptr<Message> &m,
+                                                    vector<int64> &deleted_message_ids) {
+  if (m == nullptr) {
+    return;
+  }
+  MessageId message_id = m->message_id;
+
+  if (is_debug_message_op_enabled()) {
+    d->debug_message_op.emplace_back(Dialog::MessageOp::Delete, m->message_id, m->content->get_id(), false,
+                                     m->have_previous, m->have_next, "delete all messages");
+  }
+
+  LOG(INFO) << "Delete " << message_id;
+  deleted_message_ids.push_back(message_id.get());
+
+  do_delete_all_dialog_messages(d, m->right, deleted_message_ids);
+  do_delete_all_dialog_messages(d, m->left, deleted_message_ids);
+
+  delete_active_live_location(d->dialog_id, m.get());
+
+  if (message_id.is_yet_unsent()) {
+    cancel_send_message_query(d->dialog_id, m);
+  }
+
+  switch (d->dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+      message_id_to_dialog_id_.erase(message_id);
+      break;
+    case DialogType::Channel:
+      // nothing to do
+      break;
+    case DialogType::SecretChat:
+      LOG(INFO) << "Delete correspondence random_id " << m->random_id << " to " << message_id << " in " << d->dialog_id;
+      d->random_id_to_message_id.erase(m->random_id);
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+  ttl_unregister_message(d->dialog_id, m.get(), Time::now());
+
+  m = nullptr;
+}
+
+bool MessagesManager::have_dialog(DialogId dialog_id) const {
+  return dialogs_.count(dialog_id) > 0;
+}
+
+void MessagesManager::load_dialogs(vector<DialogId> dialog_ids, Promise<Unit> &&promise) {
+  LOG(INFO) << "Load dialogs " << format::as_array(dialog_ids);
+
+  Dependencies dependencies;
+  for (auto dialog_id : dialog_ids) {
+    if (dialog_id.is_valid() && !have_dialog(dialog_id)) {
+      add_dialog_dependencies(dependencies, dialog_id);
+    }
+  }
+  resolve_dependencies_force(dependencies);
+
+  for (auto dialog_id : dialog_ids) {
+    if (dialog_id.is_valid()) {
+      force_create_dialog(dialog_id, "load_dialogs");
+    }
+  }
+
+  promise.set_value(Unit());
+}
+
+bool MessagesManager::load_dialog(DialogId dialog_id, int left_tries, Promise<Unit> &&promise) {
+  if (!dialog_id.is_valid()) {
+    promise.set_error(Status::Error(6, "Invalid chat identifier"));
+    return false;
+  }
+
+  if (!have_dialog_force(dialog_id)) {  // TODO remove _force
+    if (G()->parameters().use_message_db) {
+      //      TODO load dialog from database, DialogLoader
+      //      send_closure_later(actor_id(this), &MessagesManager::load_dialog_from_database, dialog_id,
+      //      std::move(promise));
+      //      return false;
+    }
+    if (td_->auth_manager_->is_bot()) {
+      switch (dialog_id.get_type()) {
+        case DialogType::User: {
+          auto user_id = dialog_id.get_user_id();
+          auto have_user = td_->contacts_manager_->get_user(user_id, left_tries, std::move(promise));
+          if (!have_user) {
+            return false;
+          }
+          break;
+        }
+        case DialogType::Chat: {
+          auto have_chat = td_->contacts_manager_->get_chat(dialog_id.get_chat_id(), left_tries, std::move(promise));
+          if (!have_chat) {
+            return false;
+          }
+          break;
+        }
+        case DialogType::Channel: {
+          auto have_channel =
+              td_->contacts_manager_->get_channel(dialog_id.get_channel_id(), left_tries, std::move(promise));
+          if (!have_channel) {
+            return false;
+          }
+          break;
+        }
+        case DialogType::SecretChat:
+          promise.set_error(Status::Error(6, "Chat not found"));
+          return false;
+        case DialogType::None:
+        default:
+          UNREACHABLE();
+      }
+      if (!have_input_peer(dialog_id, AccessRights::Read)) {
+        return false;
+      }
+
+      add_dialog(dialog_id);
+      return true;
+    }
+
+    promise.set_error(Status::Error(6, "Chat not found"));
+    return false;
+  }
+
+  promise.set_value(Unit());
+  return true;
+}
+
+vector<DialogId> MessagesManager::get_dialogs(DialogDate offset, int32 limit, bool force, Promise<Unit> &&promise) {
+  LOG(INFO) << "Get chats with offset " << offset << " and limit " << limit << ". Know about order of "
+            << ordered_dialogs_.size() << " chat(s). last_dialog_date_ = " << last_dialog_date_
+            << ", last_server_dialog_date_ = " << last_server_dialog_date_
+            << ", last_loaded_database_dialog_date_ = " << last_loaded_database_dialog_date_;
+
+  vector<DialogId> result;
+  if (limit <= 0) {
+    promise.set_error(Status::Error(3, "Parameter limit in getChats must be positive"));
+    return result;
+  }
+
+  if (limit > MAX_GET_DIALOGS) {
+    limit = MAX_GET_DIALOGS;
+  }
+
+  auto it = ordered_dialogs_.upper_bound(offset);
+  auto end = ordered_dialogs_.end();
+  while (it != end && limit-- > 0) {
+    result.push_back(it->get_dialog_id());
+    ++it;
+  }
+
+  if (limit <= 0 || last_dialog_date_ == MAX_DIALOG_DATE || force) {
+    promise.set_value(Unit());
+    return result;
+  }
+
+  load_dialog_list(std::move(promise));
+  return result;
+}
+
+void MessagesManager::load_dialog_list(Promise<Unit> &&promise) {
+  auto &multipromise = load_dialog_list_multipromise_;
+  multipromise.add_promise(std::move(promise));
+  if (multipromise.promise_count() != 1) {
+    // queries have already been sent, just wait for the result
+    return;
+  }
+
+  bool is_query_sent = false;
+  if (G()->parameters().use_message_db && last_loaded_database_dialog_date_ < last_database_server_dialog_date_) {
+    load_dialog_list_from_database(MAX_GET_DIALOGS, multipromise.get_promise());
+    is_query_sent = true;
+  } else {
+    LOG(INFO) << "Get dialogs from " << last_server_dialog_date_;
+    auto sequence_id = get_sequence_dispatcher_id(DialogId(), -1);
+    send_closure(td_->create_net_actor<GetPinnedDialogsQuery>(multipromise.get_promise()), &GetPinnedDialogsQuery::send,
+                 sequence_id);
+    if (last_dialog_date_ == last_server_dialog_date_) {
+      send_closure(td_->create_net_actor<GetDialogListQuery>(multipromise.get_promise()), &GetDialogListQuery::send,
+                   last_server_dialog_date_.get_date(),
+                   last_server_dialog_date_.get_message_id().get_next_server_message_id().get_server_message_id(),
+                   last_server_dialog_date_.get_dialog_id(), int32{MAX_GET_DIALOGS}, sequence_id);
+      is_query_sent = true;
+    }
+  }
+  CHECK(is_query_sent);
+}
+
+void MessagesManager::load_dialog_list_from_database(int32 limit, Promise<Unit> &&promise) {
+  LOG(INFO) << "Load dialogs from " << last_loaded_database_dialog_date_
+            << ", last database server dialog date = " << last_database_server_dialog_date_;
+
+  G()->td_db()->get_dialog_db_async()->get_dialogs(
+      last_loaded_database_dialog_date_.get_order(), last_loaded_database_dialog_date_.get_dialog_id(), limit,
+      PromiseCreator::lambda([actor_id = actor_id(this),
+                              promise = std::move(promise)](vector<BufferSlice> result) mutable {
+        send_closure(actor_id, &MessagesManager::on_get_dialogs_from_database, std::move(result), std::move(promise));
+      }));
+}
+
+void MessagesManager::on_get_dialogs_from_database(vector<BufferSlice> &&dialogs, Promise<Unit> &&promise) {
+  LOG(INFO) << "Receive " << dialogs.size() << " dialogs in result of GetDialogsFromDatabase";
+  DialogDate max_dialog_date = MIN_DIALOG_DATE;
+  for (auto &dialog : dialogs) {
+    Dialog *d = on_load_dialog_from_database(std::move(dialog));
+    CHECK(d != nullptr);
+
+    DialogDate dialog_date(d->order, d->dialog_id);
+    if (max_dialog_date < dialog_date) {
+      max_dialog_date = dialog_date;
+    }
+    LOG(INFO) << "Chat " << dialog_date << " is loaded from database";
+  }
+
+  if (dialogs.empty()) {
+    // if there is no more dialogs in the database
+    last_loaded_database_dialog_date_ = MAX_DIALOG_DATE;
+    LOG(INFO) << "Set last loaded database dialog date to " << last_loaded_database_dialog_date_;
+    last_server_dialog_date_ = max(last_server_dialog_date_, last_database_server_dialog_date_);
+    LOG(INFO) << "Set last server dialog date to " << last_server_dialog_date_;
+    update_last_dialog_date();
+  }
+  if (last_loaded_database_dialog_date_ < max_dialog_date) {
+    last_loaded_database_dialog_date_ = min(max_dialog_date, last_database_server_dialog_date_);
+    LOG(INFO) << "Set last loaded database dialog date to " << last_loaded_database_dialog_date_;
+    last_server_dialog_date_ = max(last_server_dialog_date_, last_loaded_database_dialog_date_);
+    LOG(INFO) << "Set last server dialog date to " << last_server_dialog_date_;
+    update_last_dialog_date();
+  } else if (!dialogs.empty()) {
+    LOG(ERROR) << "Last loaded database dialog date didn't increased";
+  }
+
+  if (!preload_dialog_list_timeout_.has_timeout()) {
+    LOG(INFO) << "Schedule chat list preload";
+    preload_dialog_list_timeout_.set_callback(std::move(MessagesManager::preload_dialog_list));
+    preload_dialog_list_timeout_.set_callback_data(static_cast<void *>(this));
+  }
+  preload_dialog_list_timeout_.set_timeout_in(0.2);
+
+  promise.set_value(Unit());
+}
+
+void MessagesManager::preload_dialog_list(void *messages_manager_void) {
+  if (G()->close_flag()) {
+    return;
+  }
+
+  CHECK(messages_manager_void != nullptr);
+  auto messages_manager = static_cast<MessagesManager *>(messages_manager_void);
+
+  CHECK(G()->parameters().use_message_db);
+  if (messages_manager->load_dialog_list_multipromise_.promise_count() != 0) {
+    // do nothing if there is pending load dialog list request
+    return;
+  }
+
+  if (messages_manager->ordered_dialogs_.size() > MAX_PRELOADED_DIALOGS) {
+    // do nothing if there are more than MAX_PRELOADED_DIALOGS dialogs already loaded
+    messages_manager->recalc_unread_message_count();
+    return;
+  }
+
+  if (messages_manager->last_loaded_database_dialog_date_ < messages_manager->last_database_server_dialog_date_) {
+    // if there are some dialogs in database, preload some of them
+    messages_manager->load_dialog_list_from_database(20, Auto());
+  } else if (messages_manager->last_dialog_date_ != MAX_DIALOG_DATE) {
+    messages_manager->load_dialog_list(PromiseCreator::lambda([messages_manager](Result<Unit> result) {
+      if (result.is_ok()) {
+        messages_manager->recalc_unread_message_count();
+      }
+    }));
+  } else {
+    messages_manager->recalc_unread_message_count();
+  }
+}
+
+vector<DialogId> MessagesManager::get_pinned_dialogs() const {
+  vector<DialogId> result;
+
+  auto it = ordered_dialogs_.begin();
+  auto end = ordered_dialogs_.end();
+  while (it != end && it->get_date() >= MIN_PINNED_DIALOG_DATE) {
+    result.push_back(it->get_dialog_id());
+    ++it;
+  }
+
+  return result;
+}
+
+vector<DialogId> MessagesManager::search_public_dialogs(const string &query, Promise<Unit> &&promise) {
+  LOG(INFO) << "Search public chats with query = \"" << query << '"';
+
+  if (utf8_length(query) < MIN_SEARCH_PUBLIC_DIALOG_PREFIX_LEN) {
+    string username = clean_username(query);
+    if (username[0] == '@') {
+      username = username.substr(1);
+    }
+
+    for (auto &short_username : get_valid_short_usernames()) {
+      if (2 * username.size() > short_username.size() && begins_with(short_username, username)) {
+        username = short_username.str();
+        auto it = resolved_usernames_.find(username);
+        if (it == resolved_usernames_.end()) {
+          td_->create_handler<ResolveUsernameQuery>(std::move(promise))->send(username);
+          return {};
+        }
+
+        if (it->second.expires_at < Time::now()) {
+          td_->create_handler<ResolveUsernameQuery>(Promise<>())->send(username);
+        }
+
+        auto dialog_id = it->second.dialog_id;
+        force_create_dialog(dialog_id, "public dialogs search");
+        promise.set_value(Unit());
+        return {dialog_id};
+      }
+    }
+    promise.set_value(Unit());
+    return {};
+  }
+
+  auto it = found_public_dialogs_.find(query);
+  if (it != found_public_dialogs_.end()) {
+    promise.set_value(Unit());
+    return it->second;
+  }
+
+  send_search_public_dialogs_query(query, std::move(promise));
+  return vector<DialogId>();
+}
+
+void MessagesManager::send_search_public_dialogs_query(const string &query, Promise<Unit> &&promise) {
+  auto &promises = search_public_dialogs_queries_[query];
+  promises.push_back(std::move(promise));
+  if (promises.size() != 1) {
+    // query has already been sent, just wait for the result
+    return;
+  }
+
+  td_->create_handler<SearchPublicDialogsQuery>()->send(query);
+}
+
+std::pair<size_t, vector<DialogId>> MessagesManager::search_dialogs(const string &query, int32 limit,
+                                                                    Promise<Unit> &&promise) {
+  LOG(INFO) << "Search chats with query \"" << query << "\" and limit " << limit;
+
+  if (limit < 0) {
+    promise.set_error(Status::Error(400, "Limit must be non-negative"));
+    return {};
+  }
+  if (query.empty()) {
+    if (!load_recently_found_dialogs(promise)) {
+      return {};
+    }
+
+    promise.set_value(Unit());
+    size_t result_size = min(static_cast<size_t>(limit), recently_found_dialog_ids_.size());
+    return {recently_found_dialog_ids_.size(),
+            vector<DialogId>(recently_found_dialog_ids_.begin(), recently_found_dialog_ids_.begin() + result_size)};
+  }
+
+  auto result = dialogs_hints_.search(query, limit);
+  vector<DialogId> dialog_ids;
+  dialog_ids.reserve(result.second.size());
+  for (auto key : result.second) {
+    dialog_ids.push_back(DialogId(-key));
+  }
+
+  promise.set_value(Unit());
+  return {result.first, std::move(dialog_ids)};
+}
+
+vector<DialogId> MessagesManager::sort_dialogs_by_order(const vector<DialogId> &dialog_ids, int32 limit) const {
+  auto dialog_dates = transform(dialog_ids, [this](auto dialog_id) {
+    const Dialog *d = this->get_dialog(dialog_id);
+    CHECK(d != nullptr);
+    return DialogDate(d->order, dialog_id);
+  });
+  if (static_cast<size_t>(limit) >= dialog_dates.size()) {
+    std::sort(dialog_dates.begin(), dialog_dates.end());
+  } else {
+    std::partial_sort(dialog_dates.begin(), dialog_dates.begin() + limit, dialog_dates.end());
+    dialog_dates.resize(limit, MAX_DIALOG_DATE);
+  }
+  return transform(dialog_dates, [](auto dialog_date) { return dialog_date.get_dialog_id(); });
+}
+
+vector<DialogId> MessagesManager::search_dialogs_on_server(const string &query, int32 limit, Promise<Unit> &&promise) {
+  LOG(INFO) << "Search chats on server with query \"" << query << "\" and limit " << limit;
+
+  if (limit < 0) {
+    promise.set_error(Status::Error(400, "Limit must be non-negative"));
+    return {};
+  }
+  if (limit > MAX_GET_DIALOGS) {
+    limit = MAX_GET_DIALOGS;
+  }
+
+  if (query.empty()) {
+    promise.set_value(Unit());
+    return {};
+  }
+
+  auto it = found_on_server_dialogs_.find(query);
+  if (it != found_on_server_dialogs_.end()) {
+    promise.set_value(Unit());
+    return sort_dialogs_by_order(it->second, limit);
+  }
+
+  send_search_public_dialogs_query(query, std::move(promise));
+  return vector<DialogId>();
+}
+
+vector<DialogId> MessagesManager::get_common_dialogs(UserId user_id, DialogId offset_dialog_id, int32 limit, bool force,
+                                                     Promise<Unit> &&promise) {
+  if (!td_->contacts_manager_->have_input_user(user_id)) {
+    promise.set_error(Status::Error(6, "Have no access to the user"));
+    return vector<DialogId>();
+  }
+
+  if (user_id == td_->contacts_manager_->get_my_id("get_common_dialogs")) {
+    promise.set_error(Status::Error(6, "Can't get common chats with self"));
+    return vector<DialogId>();
+  }
+  if (limit <= 0) {
+    promise.set_error(Status::Error(3, "Parameter limit must be positive"));
+    return vector<DialogId>();
+  }
+  if (limit > MAX_GET_DIALOGS) {
+    limit = MAX_GET_DIALOGS;
+  }
+
+  int32 offset_chat_id = 0;
+  switch (offset_dialog_id.get_type()) {
+    case DialogType::Chat:
+      offset_chat_id = offset_dialog_id.get_chat_id().get();
+      break;
+    case DialogType::Channel:
+      offset_chat_id = offset_dialog_id.get_channel_id().get();
+      break;
+    case DialogType::None:
+      if (offset_dialog_id == DialogId()) {
+        break;
+      }
+    // fallthrough
+    case DialogType::User:
+    case DialogType::SecretChat:
+      promise.set_error(Status::Error(6, "Wrong offset_chat_id"));
+      return vector<DialogId>();
+    default:
+      UNREACHABLE();
+      break;
+  }
+
+  auto it = found_common_dialogs_.find(user_id);
+  if (it != found_common_dialogs_.end() && !it->second.empty()) {
+    vector<DialogId> &common_dialog_ids = it->second;
+    auto offset_it = common_dialog_ids.begin();
+    if (offset_dialog_id != DialogId()) {
+      offset_it = std::find(common_dialog_ids.begin(), common_dialog_ids.end(), offset_dialog_id);
+      if (offset_it == common_dialog_ids.end()) {
+        promise.set_error(Status::Error(6, "Wrong offset_chat_id"));
+        return vector<DialogId>();
+      }
+      ++offset_it;
+    }
+    vector<DialogId> result;
+    while (result.size() < static_cast<size_t>(limit)) {
+      if (offset_it == common_dialog_ids.end()) {
+        break;
+      }
+      auto dialog_id = *offset_it++;
+      if (dialog_id == DialogId()) {  // end of the list
+        promise.set_value(Unit());
+        return result;
+      }
+      result.push_back(dialog_id);
+    }
+    if (result.size() == static_cast<size_t>(limit) || force) {
+      promise.set_value(Unit());
+      return result;
+    }
+  }
+
+  td_->create_handler<GetCommonDialogsQuery>(std::move(promise))->send(user_id, offset_chat_id, limit);
+  return vector<DialogId>();
+}
+
+void MessagesManager::on_get_common_dialogs(UserId user_id, vector<tl_object_ptr<telegram_api::Chat>> &&chats,
+                                            int32 total_count) {
+  auto &result = found_common_dialogs_[user_id];
+  if (result.size() > 0 && result.back() == DialogId()) {
+    return;
+  }
+  for (auto &chat : chats) {
+    DialogId dialog_id;
+    switch (chat->get_id()) {
+      case telegram_api::chatEmpty::ID: {
+        auto c = static_cast<const telegram_api::chatEmpty *>(chat.get());
+        ChatId chat_id(c->id_);
+        if (!chat_id.is_valid()) {
+          LOG(ERROR) << "Receive invalid " << chat_id;
+          continue;
+        }
+        dialog_id = DialogId(chat_id);
+        break;
+      }
+      case telegram_api::chat::ID: {
+        auto c = static_cast<const telegram_api::chat *>(chat.get());
+        ChatId chat_id(c->id_);
+        if (!chat_id.is_valid()) {
+          LOG(ERROR) << "Receive invalid " << chat_id;
+          continue;
+        }
+        dialog_id = DialogId(chat_id);
+        break;
+      }
+      case telegram_api::chatForbidden::ID: {
+        auto c = static_cast<const telegram_api::chatForbidden *>(chat.get());
+        ChatId chat_id(c->id_);
+        if (!chat_id.is_valid()) {
+          LOG(ERROR) << "Receive invalid " << chat_id;
+          continue;
+        }
+        dialog_id = DialogId(chat_id);
+        break;
+      }
+      case telegram_api::channel::ID: {
+        auto c = static_cast<const telegram_api::channel *>(chat.get());
+        ChannelId channel_id(c->id_);
+        if (!channel_id.is_valid()) {
+          LOG(ERROR) << "Receive invalid " << channel_id;
+          continue;
+        }
+        dialog_id = DialogId(channel_id);
+        break;
+      }
+      case telegram_api::channelForbidden::ID: {
+        auto c = static_cast<const telegram_api::channelForbidden *>(chat.get());
+        ChannelId channel_id(c->id_);
+        if (!channel_id.is_valid()) {
+          LOG(ERROR) << "Receive invalid " << channel_id;
+          continue;
+        }
+        dialog_id = DialogId(channel_id);
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+    CHECK(dialog_id.is_valid());
+    td_->contacts_manager_->on_get_chat(std::move(chat));
+
+    if (std::find(result.begin(), result.end(), dialog_id) == result.end()) {
+      force_create_dialog(dialog_id, "get common dialogs");
+      result.push_back(dialog_id);
+    }
+  }
+  if (result.size() >= static_cast<size_t>(total_count)) {
+    result.push_back(DialogId());
+  }
+}
+
+bool MessagesManager::have_message(FullMessageId full_message_id) {
+  return get_message_force(full_message_id) != nullptr;
+}
+
+MessagesManager::Message *MessagesManager::get_message(FullMessageId full_message_id) {
+  Dialog *d = get_dialog(full_message_id.get_dialog_id());
+  if (d == nullptr) {
+    return nullptr;
+  }
+
+  return get_message(d, full_message_id.get_message_id());
+}
+
+const MessagesManager::Message *MessagesManager::get_message(FullMessageId full_message_id) const {
+  const Dialog *d = get_dialog(full_message_id.get_dialog_id());
+  if (d == nullptr) {
+    return nullptr;
+  }
+
+  return get_message(d, full_message_id.get_message_id());
+}
+
+MessagesManager::Message *MessagesManager::get_message_force(FullMessageId full_message_id) {
+  Dialog *d = get_dialog_force(full_message_id.get_dialog_id());
+  if (d == nullptr) {
+    return nullptr;
+  }
+
+  return get_message_force(d, full_message_id.get_message_id());
+}
+
+MessageId MessagesManager::get_replied_message_id(const Message *m) {
+  switch (m->content->get_id()) {
+    case MessagePinMessage::ID:
+      CHECK(!m->reply_to_message_id.is_valid());
+      return static_cast<const MessagePinMessage *>(m->content.get())->message_id;
+    case MessageGameScore::ID:
+      CHECK(!m->reply_to_message_id.is_valid());
+      return static_cast<const MessageGameScore *>(m->content.get())->game_message_id;
+    case MessagePaymentSuccessful::ID:
+      CHECK(!m->reply_to_message_id.is_valid());
+      return static_cast<const MessagePaymentSuccessful *>(m->content.get())->invoice_message_id;
+    default:
+      return m->reply_to_message_id;
+  }
+}
+
+void MessagesManager::get_message_force_from_server(Dialog *d, MessageId message_id, Promise<Unit> &&promise,
+                                                    tl_object_ptr<telegram_api::InputMessage> input_message) {
+  auto m = get_message_force(d, message_id);
+  if (m == nullptr && message_id.is_valid() && message_id.is_server()) {
+    auto dialog_type = d->dialog_id.get_type();
+    if (d->last_new_message_id != MessageId() && message_id.get() > d->last_new_message_id.get()) {
+      // message will not be added to the dialog anyway
+      if (dialog_type == DialogType::Channel) {
+        // so we try to force channel difference first
+        CHECK(input_message == nullptr);  // replied message can't be older than already added original message
+        postponed_get_message_requests_[d->dialog_id].emplace_back(message_id, std::move(promise));
+        get_channel_difference(d->dialog_id, d->pts, true, "get_message");
+      } else {
+        promise.set_value(Unit());
+      }
+      return;
+    }
+
+    if (d->deleted_message_ids.count(message_id) == 0 && dialog_type != DialogType::SecretChat) {
+      return get_messages_from_server({FullMessageId(d->dialog_id, message_id)}, std::move(promise),
+                                      std::move(input_message));
+    }
+  }
+
+  promise.set_value(Unit());
+}
+
+void MessagesManager::get_message(FullMessageId full_message_id, Promise<Unit> &&promise) {
+  Dialog *d = get_dialog_force(full_message_id.get_dialog_id());
+  if (d == nullptr) {
+    return promise.set_error(Status::Error(6, "Chat not found"));
+  }
+
+  get_message_force_from_server(d, full_message_id.get_message_id(), std::move(promise));
+}
+
+MessageId MessagesManager::get_replied_message(DialogId dialog_id, MessageId message_id, bool force,
+                                               Promise<Unit> &&promise) {
+  LOG(INFO) << "Get replied message to " << message_id << " in " << dialog_id;
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    promise.set_error(Status::Error(6, "Chat not found"));
+    return MessageId();
+  }
+
+  auto m = get_message_force(d, message_id);
+  if (m == nullptr) {
+    if (force) {
+      promise.set_value(Unit());
+    } else {
+      get_message_force_from_server(d, message_id, std::move(promise));
+    }
+    return MessageId();
+  }
+
+  tl_object_ptr<telegram_api::InputMessage> input_message;
+  if (message_id.is_server()) {
+    input_message = make_tl_object<telegram_api::inputMessageReplyTo>(message_id.get_server_message_id().get());
+  }
+  auto replied_message_id = get_replied_message_id(m);
+  get_message_force_from_server(d, replied_message_id, std::move(promise), std::move(input_message));
+
+  return replied_message_id;
+}
+
+void MessagesManager::get_dialog_pinned_message(DialogId dialog_id, Promise<MessageId> &&promise) {
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return promise.set_error(Status::Error(6, "Chat not found"));
+  }
+
+  if (dialog_id.get_type() != DialogType::Channel) {
+    return promise.set_value(MessageId());
+  }
+
+  auto channel_id = dialog_id.get_channel_id();
+  auto message_id = td_->contacts_manager_->get_channel_pinned_message_id(channel_id);
+  if (get_message_force(d, message_id) == nullptr) {
+    return td_->create_handler<GetChannelPinnedMessageQuery>(std::move(promise))->send(channel_id);
+  }
+
+  promise.set_value(std::move(message_id));
+}
+
+bool MessagesManager::get_messages(DialogId dialog_id, const vector<MessageId> &message_ids, Promise<Unit> &&promise) {
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    promise.set_error(Status::Error(6, "Chat not found"));
+    return false;
+  }
+
+  bool is_secret = dialog_id.get_type() == DialogType::SecretChat;
+  vector<FullMessageId> missed_message_ids;
+  for (auto message_id : message_ids) {
+    if (!message_id.is_valid()) {
+      promise.set_error(Status::Error(6, "Invalid message identifier"));
+      return false;
+    }
+
+    auto message = get_message_force(d, message_id);
+    if (message == nullptr && message_id.is_server() && !is_secret) {
+      missed_message_ids.emplace_back(dialog_id, message_id);
+      continue;
+    }
+  }
+
+  if (!missed_message_ids.empty()) {
+    get_messages_from_server(std::move(missed_message_ids), std::move(promise));
+    return false;
+  }
+
+  promise.set_value(Unit());
+  return true;
+}
+
+void MessagesManager::get_messages_from_server(vector<FullMessageId> &&message_ids, Promise<Unit> &&promise,
+                                               tl_object_ptr<telegram_api::InputMessage> input_message) {
+  if (message_ids.empty()) {
+    LOG(ERROR) << "Empty message_ids";
+    return;
+  }
+
+  if (input_message != nullptr) {
+    CHECK(message_ids.size() == 1);
+  }
+
+  vector<tl_object_ptr<telegram_api::InputMessage>> ordinary_message_ids;
+  std::unordered_map<ChannelId, vector<tl_object_ptr<telegram_api::InputMessage>>, ChannelIdHash> channel_message_ids;
+  for (auto &full_message_id : message_ids) {
+    auto dialog_id = full_message_id.get_dialog_id();
+    auto message_id = full_message_id.get_message_id();
+    if (!message_id.is_valid() || !message_id.is_server()) {
+      continue;
+    }
+
+    switch (dialog_id.get_type()) {
+      case DialogType::User:
+      case DialogType::Chat:
+        ordinary_message_ids.push_back(input_message == nullptr ? get_input_message(message_id)
+                                                                : std::move(input_message));
+        break;
+      case DialogType::Channel:
+        channel_message_ids[dialog_id.get_channel_id()].push_back(
+            input_message == nullptr ? get_input_message(message_id) : std::move(input_message));
+        break;
+      case DialogType::SecretChat:
+        LOG(ERROR) << "Can't get secret chat message from server";
+        break;
+      case DialogType::None:
+      default:
+        UNREACHABLE();
+        break;
+    }
+  }
+
+  // TODO MultiPromise
+  size_t query_count = !ordinary_message_ids.empty() + channel_message_ids.size();
+  LOG_IF(ERROR, query_count > 1 && promise) << "Promise will be called after first query returns";
+
+  if (!ordinary_message_ids.empty()) {
+    td_->create_handler<GetMessagesQuery>(std::move(promise))->send(std::move(ordinary_message_ids));
+  }
+
+  for (auto &it : channel_message_ids) {
+    auto input_channel = td_->contacts_manager_->get_input_channel(it.first);
+    if (input_channel == nullptr) {
+      LOG(ERROR) << "Can't find info about " << it.first << " to get a message from it";
+      promise.set_error(Status::Error(6, "Can't access the chat"));
+      continue;
+    }
+    td_->create_handler<GetChannelMessagesQuery>(std::move(promise))
+        ->send(it.first, std::move(input_channel), std::move(it.second));
+  }
+}
+
+bool MessagesManager::is_message_edited_recently(FullMessageId full_message_id, int32 seconds) {
+  if (seconds < 0) {
+    return false;
+  }
+
+  auto m = get_message_force(full_message_id);
+  if (m == nullptr) {
+    return true;
+  }
+
+  return m->edit_date >= G()->unix_time() - seconds;
+}
+
+std::pair<string, string> MessagesManager::get_public_message_link(FullMessageId full_message_id, bool for_group,
+                                                                   Promise<Unit> &&promise) {
+  auto dialog_id = full_message_id.get_dialog_id();
+  auto d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    promise.set_error(Status::Error(6, "Chat not found"));
+    return {};
+  }
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    promise.set_error(Status::Error(6, "Can't access the chat"));
+    return {};
+  }
+  if (dialog_id.get_type() != DialogType::Channel ||
+      td_->contacts_manager_->get_channel_username(dialog_id.get_channel_id()).empty()) {
+    promise.set_error(Status::Error(
+        6, "Public message links are available only for messages in public supergroups and channel chats"));
+    return {};
+  }
+
+  auto message_id = full_message_id.get_message_id();
+  auto message = get_message_force(d, message_id);
+  if (message == nullptr) {
+    promise.set_error(Status::Error(6, "Message not found"));
+    return {};
+  }
+  if (!message_id.is_server()) {
+    promise.set_error(Status::Error(6, "Message is local"));
+    return {};
+  }
+
+  auto it = public_message_links_[for_group].find(full_message_id);
+  if (it == public_message_links_[for_group].end()) {
+    td_->create_handler<ExportChannelMessageLinkQuery>(std::move(promise))
+        ->send(dialog_id.get_channel_id(), message_id, for_group);
+    return {};
+  }
+
+  promise.set_value(Unit());
+  return it->second;
+}
+
+void MessagesManager::on_get_public_message_link(FullMessageId full_message_id, bool for_group, string url,
+                                                 string html) {
+  LOG_IF(ERROR, url.empty() && html.empty()) << "Receive empty public link for " << full_message_id;
+  public_message_links_[for_group][full_message_id] = {std::move(url), std::move(html)};
+}
+
+Status MessagesManager::delete_dialog_reply_markup(DialogId dialog_id, MessageId message_id) {
+  if (td_->auth_manager_->is_bot()) {
+    return Status::Error(6, "Bots can't delete chat reply markup");
+  }
+  if (!message_id.is_valid()) {
+    return Status::Error(6, "Invalid message id specified");
+  }
+
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return Status::Error(6, "Chat not found");
+  }
+  if (d->reply_markup_message_id != message_id) {
+    return Status::OK();
+  }
+
+  const Message *message = get_message_force(d, message_id);
+  CHECK(message != nullptr);
+  CHECK(message->reply_markup != nullptr);
+
+  if (message->reply_markup->type == ReplyMarkup::Type::ForceReply) {
+    set_dialog_reply_markup(d, MessageId());
+  } else if (message->reply_markup->type == ReplyMarkup::Type::ShowKeyboard) {
+    if (!message->reply_markup->is_one_time_keyboard) {
+      return Status::Error(6, "Do not need to delete non one-time keyboard");
+    }
+    if (message->reply_markup->is_personal) {
+      message->reply_markup->is_personal = false;
+      set_dialog_reply_markup(d, message_id);
+
+      on_message_changed(d, message, "delete_dialog_reply_markup");
+    }
+  } else {
+    // non-bots can't have messages with RemoveKeyboard
+    UNREACHABLE();
+  }
+  return Status::OK();
+}
+
+class MessagesManager::SaveDialogDraftMessageOnServerLogEvent {
+ public:
+  DialogId dialog_id_;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(dialog_id_, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(dialog_id_, parser);
+  }
+};
+
+Status MessagesManager::set_dialog_draft_message(DialogId dialog_id,
+                                                 tl_object_ptr<td_api::draftMessage> &&draft_message) {
+  if (td_->auth_manager_->is_bot()) {
+    return Status::Error(6, "Bots can't change chat draft message");
+  }
+
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return Status::Error(6, "Chat not found");
+  }
+  TRY_STATUS(can_send_message(dialog_id));
+
+  unique_ptr<DraftMessage> new_draft_message;
+  if (draft_message != nullptr) {
+    new_draft_message = make_unique<DraftMessage>();
+    new_draft_message->date = G()->unix_time();
+    new_draft_message->reply_to_message_id = get_reply_to_message_id(d, MessageId(draft_message->reply_to_message_id_));
+
+    auto input_message_content = std::move(draft_message->input_message_text_);
+    if (input_message_content != nullptr) {
+      int32 draft_message_content_type = input_message_content->get_id();
+      if (draft_message_content_type != td_api::inputMessageText::ID) {
+        return Status::Error(5, "Input message content type must be InputMessageText");
+      }
+      TRY_RESULT(message_content, process_input_message_text(dialog_id, std::move(input_message_content), false, true));
+      new_draft_message->input_message_text = std::move(message_content);
+    }
+
+    if (!new_draft_message->reply_to_message_id.is_valid() && new_draft_message->input_message_text.text.text.empty()) {
+      new_draft_message = nullptr;
+    }
+  }
+
+  if (update_dialog_draft_message(d, std::move(new_draft_message), false, true)) {
+    if (dialog_id.get_type() != DialogType::SecretChat) {
+      if (G()->parameters().use_message_db) {
+        LOG(INFO) << "Save draft of " << dialog_id << " to binlog";
+        SaveDialogDraftMessageOnServerLogEvent logevent;
+        logevent.dialog_id_ = dialog_id;
+        auto storer = LogEventStorerImpl<SaveDialogDraftMessageOnServerLogEvent>(logevent);
+        if (d->save_draft_message_logevent_id == 0) {
+          d->save_draft_message_logevent_id = BinlogHelper::add(
+              G()->td_db()->get_binlog(), LogEvent::HandlerType::SaveDialogDraftMessageOnServer, storer);
+          LOG(INFO) << "Add draft logevent " << d->save_draft_message_logevent_id;
+        } else {
+          auto new_logevent_id = BinlogHelper::rewrite(G()->td_db()->get_binlog(), d->save_draft_message_logevent_id,
+                                                       LogEvent::HandlerType::SaveDialogDraftMessageOnServer, storer);
+          LOG(INFO) << "Rewrite draft logevent " << d->save_draft_message_logevent_id << " with " << new_logevent_id;
+        }
+        d->save_draft_message_logevent_id_generation++;
+      }
+
+      pending_draft_message_timeout_.set_timeout_in(dialog_id.get(), d->is_opened ? MIN_SAVE_DRAFT_DELAY : 0);
+    }
+  }
+  return Status::OK();
+}
+
+void MessagesManager::save_dialog_draft_message_on_server(DialogId dialog_id) {
+  auto d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+
+  Promise<> promise;
+  if (d->save_draft_message_logevent_id != 0) {
+    promise = PromiseCreator::lambda(
+        [actor_id = actor_id(this), dialog_id,
+         generation = d->save_draft_message_logevent_id_generation](Result<Unit> result) mutable {
+          if (!G()->close_flag()) {
+            send_closure(actor_id, &MessagesManager::on_saved_dialog_draft_message, dialog_id, generation);
+          }
+        });
+  }
+
+  // TODO do not send two queries simultaneously or use SequenceDispatcher
+  td_->create_handler<SaveDraftMessageQuery>(std::move(promise))->send(dialog_id, d->draft_message);
+}
+
+void MessagesManager::on_saved_dialog_draft_message(DialogId dialog_id, uint64 generation) {
+  auto d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+  LOG(INFO) << "Saved draft in " << dialog_id << " with logevent " << d->save_draft_message_logevent_id;
+  if (d->save_draft_message_logevent_id_generation == generation) {
+    CHECK(d->save_draft_message_logevent_id != 0);
+    LOG(INFO) << "Delete draft logevent " << d->save_draft_message_logevent_id;
+    BinlogHelper::erase(G()->td_db()->get_binlog(), d->save_draft_message_logevent_id);
+    d->save_draft_message_logevent_id = 0;
+  }
+}
+
+int32 MessagesManager::get_pinned_dialogs_limit() {
+  int32 limit = G()->shared_config().get_option_integer("pinned_chat_count_max");
+  if (limit <= 0) {
+    const int32 DEFAULT_PINNED_DIALOGS_LIMIT = 5;
+    return DEFAULT_PINNED_DIALOGS_LIMIT;
+  }
+  return limit;
+}
+
+vector<DialogId> MessagesManager::remove_secret_chat_dialog_ids(vector<DialogId> dialog_ids) {
+  dialog_ids.erase(std::remove_if(dialog_ids.begin(), dialog_ids.end(),
+                                  [](DialogId dialog_id) { return dialog_id.get_type() == DialogType::SecretChat; }),
+                   dialog_ids.end());
+  return dialog_ids;
+}
+
+Status MessagesManager::toggle_dialog_is_pinned(DialogId dialog_id, bool is_pinned) {
+  if (td_->auth_manager_->is_bot()) {
+    return Status::Error(6, "Bots can't change chat pin state");
+  }
+
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return Status::Error(6, "Chat not found");
+  }
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    return Status::Error(6, "Can't access the chat");
+  }
+
+  bool was_pinned = d->pinned_order != DEFAULT_ORDER;
+  if (is_pinned == was_pinned) {
+    return Status::OK();
+  }
+
+  if (is_pinned) {
+    auto pinned_dialog_ids = get_pinned_dialogs();
+    auto pinned_dialog_count = pinned_dialog_ids.size();
+    auto secret_pinned_dialog_count =
+        std::count_if(pinned_dialog_ids.begin(), pinned_dialog_ids.end(),
+                      [](DialogId dialog_id) { return dialog_id.get_type() == DialogType::SecretChat; });
+    size_t dialog_count = dialog_id.get_type() == DialogType::SecretChat
+                              ? secret_pinned_dialog_count
+                              : pinned_dialog_count - secret_pinned_dialog_count;
+
+    if (dialog_count >= static_cast<size_t>(get_pinned_dialogs_limit())) {
+      return Status::Error(400, "Maximum number of pinned chats exceeded");
+    }
+  }
+
+  set_dialog_is_pinned(d, is_pinned);
+  update_dialog_pos(d, false, "toggle_dialog_is_pinned");
+
+  toggle_dialog_is_pinned_on_server(dialog_id, is_pinned, 0);
+  return Status::OK();
+}
+
+class MessagesManager::ToggleDialogIsPinnedOnServerLogEvent {
+ public:
+  DialogId dialog_id_;
+  bool is_pinned_;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    BEGIN_STORE_FLAGS();
+    STORE_FLAG(is_pinned_);
+    END_STORE_FLAGS();
+
+    td::store(dialog_id_, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    BEGIN_PARSE_FLAGS();
+    PARSE_FLAG(is_pinned_);
+    END_PARSE_FLAGS();
+
+    td::parse(dialog_id_, parser);
+  }
+};
+
+void MessagesManager::toggle_dialog_is_pinned_on_server(DialogId dialog_id, bool is_pinned, uint64 logevent_id) {
+  if (logevent_id == 0 && G()->parameters().use_message_db) {
+    ToggleDialogIsPinnedOnServerLogEvent logevent;
+    logevent.dialog_id_ = dialog_id;
+    logevent.is_pinned_ = is_pinned;
+
+    auto storer = LogEventStorerImpl<ToggleDialogIsPinnedOnServerLogEvent>(logevent);
+    logevent_id =
+        BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::ToggleDialogIsPinnedOnServer, storer);
+  }
+
+  Promise<> promise;
+  if (logevent_id != 0) {
+    promise = PromiseCreator::lambda([logevent_id](Result<Unit> result) mutable {
+      if (!G()->close_flag()) {
+        BinlogHelper::erase(G()->td_db()->get_binlog(), logevent_id);
+      }
+    });
+  }
+
+  td_->create_handler<ToggleDialogPinQuery>(std::move(promise))->send(dialog_id, is_pinned);
+}
+
+Status MessagesManager::set_pinned_dialogs(vector<DialogId> dialog_ids) {
+  if (td_->auth_manager_->is_bot()) {
+    return Status::Error(6, "Bots can't reorder pinned chats");
+  }
+
+  int32 dialog_count = 0;
+  int32 secret_dialog_count = 0;
+  auto dialog_count_limit = get_pinned_dialogs_limit();
+  for (auto dialog_id : dialog_ids) {
+    Dialog *d = get_dialog_force(dialog_id);
+    if (d == nullptr) {
+      return Status::Error(6, "Chat not found");
+    }
+    if (!have_input_peer(dialog_id, AccessRights::Read)) {
+      return Status::Error(6, "Can't access the chat");
+    }
+    if (dialog_id.get_type() == DialogType::SecretChat) {
+      secret_dialog_count++;
+    } else {
+      dialog_count++;
+    }
+
+    if (dialog_count > dialog_count_limit || secret_dialog_count > dialog_count_limit) {
+      return Status::Error(400, "Maximum number of pinned chats exceeded");
+    }
+  }
+  std::unordered_set<DialogId, DialogIdHash> new_pinned_dialog_ids(dialog_ids.begin(), dialog_ids.end());
+  if (new_pinned_dialog_ids.size() != dialog_ids.size()) {
+    return Status::Error(400, "Duplicate chats in the list of pinned chats");
+  }
+
+  auto pinned_dialog_ids = get_pinned_dialogs();
+  if (pinned_dialog_ids == dialog_ids) {
+    return Status::OK();
+  }
+  LOG(INFO) << "Reorder pinned chats order from " << format::as_array(pinned_dialog_ids) << " to "
+            << format::as_array(dialog_ids);
+
+  auto server_old_dialog_ids = remove_secret_chat_dialog_ids(pinned_dialog_ids);
+  auto server_new_dialog_ids = remove_secret_chat_dialog_ids(dialog_ids);
+
+  std::reverse(pinned_dialog_ids.begin(), pinned_dialog_ids.end());
+  std::reverse(dialog_ids.begin(), dialog_ids.end());
+
+  std::unordered_set<DialogId, DialogIdHash> old_pinned_dialog_ids(pinned_dialog_ids.begin(), pinned_dialog_ids.end());
+  auto old_it = pinned_dialog_ids.begin();
+  for (auto dialog_id : dialog_ids) {
+    old_pinned_dialog_ids.erase(dialog_id);
+    while (old_it < pinned_dialog_ids.end()) {
+      if (*old_it == dialog_id) {
+        break;
+      }
+      old_it++;
+    }
+    if (old_it < pinned_dialog_ids.end()) {
+      // leave dialog where it is
+      continue;
+    }
+    set_dialog_is_pinned(dialog_id, true);
+  }
+  for (auto dialog_id : old_pinned_dialog_ids) {
+    set_dialog_is_pinned(dialog_id, false);
+  }
+
+  if (server_old_dialog_ids != server_new_dialog_ids) {
+    reorder_pinned_dialogs_on_server(server_new_dialog_ids, 0);
+  }
+  return Status::OK();
+}
+
+class MessagesManager::ReorderPinnedDialogsOnServerLogEvent {
+ public:
+  vector<DialogId> dialog_ids_;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(dialog_ids_, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(dialog_ids_, parser);
+  }
+};
+
+void MessagesManager::reorder_pinned_dialogs_on_server(const vector<DialogId> &dialog_ids, uint64 logevent_id) {
+  if (logevent_id == 0 && G()->parameters().use_message_db) {
+    ReorderPinnedDialogsOnServerLogEvent logevent;
+    logevent.dialog_ids_ = dialog_ids;
+
+    auto storer = LogEventStorerImpl<ReorderPinnedDialogsOnServerLogEvent>(logevent);
+    logevent_id =
+        BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::ReorderPinnedDialogsOnServer, storer);
+  }
+
+  Promise<> promise;
+  if (logevent_id != 0) {
+    promise = PromiseCreator::lambda([logevent_id](Result<Unit> result) mutable {
+      if (!G()->close_flag()) {
+        BinlogHelper::erase(G()->td_db()->get_binlog(), logevent_id);
+      }
+    });
+  }
+
+  td_->create_handler<ReorderPinnedDialogsQuery>(std::move(promise))->send(dialog_ids);
+}
+
+Status MessagesManager::set_dialog_client_data(DialogId dialog_id, string &&client_data) {
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return Status::Error(6, "Chat not found");
+  }
+
+  d->client_data = std::move(client_data);
+  on_dialog_updated(d->dialog_id, "set_dialog_client_data");
+  return Status::OK();
+}
+
+void MessagesManager::create_dialog(DialogId dialog_id, bool force, Promise<Unit> &&promise) {
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    if (!have_dialog_info_force(dialog_id)) {
+      return promise.set_error(Status::Error(6, "Chat info not found"));
+    }
+    if (!have_input_peer(dialog_id, AccessRights::Read)) {
+      return promise.set_error(Status::Error(6, "Can't access the chat"));
+    }
+  }
+
+  if (force || td_->auth_manager_->is_bot() || dialog_id.get_type() == DialogType::SecretChat) {
+    force_create_dialog(dialog_id, "create dialog");
+  } else {
+    const Dialog *d = get_dialog_force(dialog_id);
+    if (d == nullptr || !d->notification_settings.is_synchronized) {
+      return send_get_dialog_query(dialog_id, std::move(promise));
+    }
+  }
+
+  promise.set_value(Unit());
+}
+
+DialogId MessagesManager::create_new_group_chat(const vector<UserId> &user_ids, const string &title, int64 &random_id,
+                                                Promise<Unit> &&promise) {
+  LOG(INFO) << "Trying to create group chat \"" << title << "\" with members " << format::as_array(user_ids);
+
+  if (random_id != 0) {
+    // request has already been sent before
+    auto it = created_dialogs_.find(random_id);
+    CHECK(it != created_dialogs_.end());
+    auto dialog_id = it->second;
+    CHECK(dialog_id.get_type() == DialogType::Chat);
+    CHECK(have_dialog(dialog_id));
+
+    created_dialogs_.erase(it);
+
+    // set default notification settings to newly created chat
+    on_update_notify_settings(dialog_id.get(),
+                              make_tl_object<telegram_api::peerNotifySettings>(1, true, false, 0, "default"));
+
+    promise.set_value(Unit());
+    return dialog_id;
+  }
+
+  if (user_ids.empty()) {
+    promise.set_error(Status::Error(3, "Too few users to create basic group chat"));
+    return DialogId();
+  }
+
+  auto new_title = clean_name(title, MAX_NAME_LENGTH);
+  if (new_title.empty()) {
+    promise.set_error(Status::Error(3, "Title can't be empty"));
+    return DialogId();
+  }
+
+  vector<tl_object_ptr<telegram_api::InputUser>> input_users;
+  for (auto user_id : user_ids) {
+    auto input_user = td_->contacts_manager_->get_input_user(user_id);
+    if (input_user == nullptr) {
+      promise.set_error(Status::Error(3, "User not found"));
+      return DialogId();
+    }
+    input_users.push_back(std::move(input_user));
+  }
+
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 || created_dialogs_.find(random_id) != created_dialogs_.end());
+  created_dialogs_[random_id];  // reserve place for result
+
+  td_->create_handler<CreateChatQuery>(std::move(promise))->send(std::move(input_users), new_title, random_id);
+  return DialogId();
+}
+
+DialogId MessagesManager::create_new_channel_chat(const string &title, bool is_megagroup, const string &description,
+                                                  int64 &random_id, Promise<Unit> &&promise) {
+  LOG(INFO) << "Trying to create " << (is_megagroup ? "supergroup" : "broadcast") << " with title \"" << title
+            << "\" and description \"" << description << "\"";
+
+  if (random_id != 0) {
+    // request has already been sent before
+    auto it = created_dialogs_.find(random_id);
+    CHECK(it != created_dialogs_.end());
+    auto dialog_id = it->second;
+    CHECK(dialog_id.get_type() == DialogType::Channel);
+    CHECK(have_dialog(dialog_id));
+
+    created_dialogs_.erase(it);
+
+    // set default notification settings to newly created chat
+    on_update_notify_settings(dialog_id.get(),
+                              make_tl_object<telegram_api::peerNotifySettings>(1, true, false, 0, "default"));
+
+    promise.set_value(Unit());
+    return dialog_id;
+  }
+
+  auto new_title = clean_name(title, MAX_NAME_LENGTH);
+  if (new_title.empty()) {
+    promise.set_error(Status::Error(3, "Title can't be empty"));
+    return DialogId();
+  }
+
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 || created_dialogs_.find(random_id) != created_dialogs_.end());
+  created_dialogs_[random_id];  // reserve place for result
+
+  td_->create_handler<CreateChannelQuery>(std::move(promise))
+      ->send(new_title, is_megagroup, strip_empty_characters(description, MAX_NAME_LENGTH), random_id);
+  return DialogId();
+}
+
+void MessagesManager::create_new_secret_chat(UserId user_id, Promise<SecretChatId> &&promise) {
+  auto user_base = td_->contacts_manager_->get_input_user(user_id);
+  if (user_base == nullptr || user_base->get_id() != telegram_api::inputUser::ID) {
+    return promise.set_error(Status::Error(6, "User not found"));
+  }
+  auto user = move_tl_object_as<telegram_api::inputUser>(user_base);
+
+  send_closure(G()->secret_chats_manager(), &SecretChatsManager::create_chat, user->user_id_, user->access_hash_,
+               std::move(promise));
+}
+
+DialogId MessagesManager::migrate_dialog_to_megagroup(DialogId dialog_id, Promise<Unit> &&promise) {
+  LOG(INFO) << "Trying to convert " << dialog_id << " to supergroup";
+
+  if (dialog_id.get_type() != DialogType::Chat) {
+    promise.set_error(Status::Error(3, "Only basic group chats can be converted to supergroup"));
+    return DialogId();
+  }
+
+  auto channel_id = td_->contacts_manager_->migrate_chat_to_megagroup(dialog_id.get_chat_id(), promise);
+  if (!channel_id.is_valid()) {
+    return DialogId();
+  }
+
+  if (!td_->contacts_manager_->have_channel(channel_id)) {
+    LOG(ERROR) << "Can't find info about supergroup to which the group has migrated";
+    promise.set_error(Status::Error(6, "Supergroup is not found"));
+    return DialogId();
+  }
+
+  auto new_dialog_id = DialogId(channel_id);
+  Dialog *d = get_dialog_force(new_dialog_id);
+  if (d == nullptr) {
+    d = add_dialog(new_dialog_id);
+    if (d->pts == 0) {
+      d->pts = 1;
+      if (is_debug_message_op_enabled()) {
+        d->debug_message_op.emplace_back(Dialog::MessageOp::SetPts, MessageId(), d->pts, false, false, false,
+                                         "migrate");
+      }
+    }
+    update_dialog_pos(d, false, "migrate_dialog_to_megagroup");
+  }
+
+  promise.set_value(Unit());
+  return new_dialog_id;
+}
+
+Status MessagesManager::open_dialog(DialogId dialog_id) {
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return Status::Error(3, "Chat not found");
+  }
+
+  open_dialog(d);
+  return Status::OK();
+}
+
+Status MessagesManager::close_dialog(DialogId dialog_id) {
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return Status::Error(3, "Chat not found");
+  }
+
+  close_dialog(d);
+  return Status::OK();
+}
+
+Status MessagesManager::view_messages(DialogId dialog_id, const vector<MessageId> &message_ids, bool force_read) {
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return Status::Error(3, "Chat not found");
+  }
+  for (auto message_id : message_ids) {
+    if (!message_id.is_valid()) {
+      return Status::Error(3, "Invalid message identifier");
+    }
+  }
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    return Status::Error(5, "Can't access the chat");
+  }
+
+  bool need_read = force_read || d->is_opened;
+  bool is_secret = dialog_id.get_type() == DialogType::SecretChat;
+  MessageId max_incoming_message_id;
+  MessageId max_message_id;
+  vector<MessageId> read_content_message_ids;
+  for (auto message_id : message_ids) {
+    auto message = get_message_force(d, message_id);
+    if (message != nullptr) {
+      if (message_id.is_server() && message->views > 0) {
+        d->pending_viewed_message_ids.insert(message_id);
+      }
+
+      if (!message_id.is_yet_unsent() && message_id.get() > max_incoming_message_id.get()) {
+        if (!message->is_outgoing && (message_id.is_server() || is_secret)) {
+          max_incoming_message_id = message_id;
+        }
+        if (message_id.get() > max_message_id.get()) {
+          max_message_id = message_id;
+        }
+      }
+
+      if (need_read) {
+        auto message_content_type = message->content->get_id();
+        if (message_content_type != MessageVoiceNote::ID && message_content_type != MessageVideoNote::ID &&
+            update_message_contains_unread_mention(d, message, false, "view_messages")) {
+          CHECK(message_id.is_server());
+          read_content_message_ids.push_back(message_id);
+          on_message_changed(d, message, "view_messages");
+        }
+      }
+    }
+  }
+  if (!d->pending_viewed_message_ids.empty()) {
+    pending_message_views_timeout_.add_timeout_in(dialog_id.get(), MAX_MESSAGE_VIEW_DELAY);
+    d->increment_view_counter |= d->is_opened;
+  }
+  if (!read_content_message_ids.empty()) {
+    read_message_contents_on_server(dialog_id, std::move(read_content_message_ids), 0);
+  }
+
+  if (need_read && max_message_id.get() > d->last_read_inbox_message_id.get()) {
+    MessageId last_read_message_id = d->last_message_id;
+    if (!last_read_message_id.is_valid() || last_read_message_id.is_yet_unsent()) {
+      if (max_message_id.get() <= d->last_new_message_id.get()) {
+        last_read_message_id = d->last_new_message_id;
+      } else {
+        last_read_message_id = max_message_id;
+      }
+    }
+    read_history_inbox(d->dialog_id, last_read_message_id, -1, "view_messages");
+
+    if (d->last_new_message_id.is_valid()) {
+      if (!d->is_last_read_inbox_message_id_inited) {
+        // don't know last read inbox message, read history on the server just in case
+        read_history_on_server(d->dialog_id, d->last_new_message_id, true, 0);
+      } else {
+        if (max_incoming_message_id.get() <= d->last_read_inbox_message_id.get()) {
+          MessagesConstIterator p(d, d->last_message_id);
+          while (*p != nullptr && ((*p)->is_outgoing || !((*p)->message_id.is_server() || is_secret)) &&
+                 (*p)->message_id.get() > d->last_read_inbox_message_id.get()) {
+            --p;
+          }
+          if (*p != nullptr && !(*p)->is_outgoing && ((*p)->message_id.is_server() || is_secret)) {
+            max_incoming_message_id = (*p)->message_id;
+          }
+        }
+
+        if (max_incoming_message_id.get() > d->last_read_inbox_message_id.get()) {
+          LOG_IF(ERROR, d->server_unread_count + d->local_unread_count == 0) << "Nave no unread messages";
+          read_history_on_server(d->dialog_id, d->last_new_message_id, false,
+                                 0);  // TODO can read messages only up to max_incoming_message_id
+        } else {
+          // can't find last incoming message, read history on the server just in case
+          read_history_on_server(d->dialog_id, d->last_new_message_id, true, 0);
+        }
+      }
+    }
+  }
+
+  return Status::OK();
+}
+
+Status MessagesManager::open_message_content(FullMessageId full_message_id) {
+  auto dialog_id = full_message_id.get_dialog_id();
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return Status::Error(3, "Chat not found");
+  }
+
+  auto message_id = full_message_id.get_message_id();
+  auto message = get_message_force(d, message_id);
+  if (message == nullptr) {
+    return Status::Error(4, "Message not found");
+  }
+
+  if (message_id.is_yet_unsent() || message->is_outgoing) {
+    return Status::OK();
+  }
+
+  if (read_message_content(d, message, true, "open_message_content") &&
+      (message_id.is_server() || dialog_id.get_type() == DialogType::SecretChat)) {
+    read_message_contents_on_server(dialog_id, {message_id}, 0);
+  }
+
+  return Status::OK();
+}
+
+class MessagesManager::ReadMessageContentsOnServerLogEvent {
+ public:
+  DialogId dialog_id_;
+  vector<MessageId> message_ids_;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(dialog_id_, storer);
+    td::store(message_ids_, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(dialog_id_, parser);
+    td::parse(message_ids_, parser);
+  }
+};
+
+void MessagesManager::read_message_contents_on_server(DialogId dialog_id, vector<MessageId> message_ids,
+                                                      uint64 logevent_id) {
+  CHECK(!message_ids.empty());
+
+  LOG(INFO) << "Read contents of " << format::as_array(message_ids) << " in " << dialog_id << " on server";
+
+  if (logevent_id == 0 && G()->parameters().use_message_db) {
+    ReadMessageContentsOnServerLogEvent logevent;
+    logevent.dialog_id_ = dialog_id;
+    logevent.message_ids_ = message_ids;
+
+    auto storer = LogEventStorerImpl<ReadMessageContentsOnServerLogEvent>(logevent);
+    logevent_id =
+        BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::ReadMessageContentsOnServer, storer);
+  }
+
+  Promise<> promise;
+  if (logevent_id != 0) {
+    promise = PromiseCreator::lambda([logevent_id](Result<Unit> result) mutable {
+      if (!G()->close_flag()) {
+        BinlogHelper::erase(G()->td_db()->get_binlog(), logevent_id);
+      }
+    });
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+      td_->create_handler<ReadMessagesContentsQuery>(std::move(promise))->send(std::move(message_ids));
+      break;
+    case DialogType::Channel:
+      td_->create_handler<ReadChannelMessagesContentsQuery>(std::move(promise))
+          ->send(dialog_id.get_channel_id(), std::move(message_ids));
+      break;
+    case DialogType::SecretChat:
+      CHECK(message_ids.size() == 1);
+      for (auto message_id : message_ids) {
+        auto m = get_message_force({dialog_id, message_id});
+        if (m != nullptr) {
+          send_closure(G()->secret_chats_manager(), &SecretChatsManager::send_open_message,
+                       dialog_id.get_secret_chat_id(), m->random_id, std::move(promise));
+        }
+      }
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+}
+
+void MessagesManager::open_dialog(Dialog *d) {
+  if (d->is_opened || !have_input_peer(d->dialog_id, AccessRights::Read)) {
+    return;
+  }
+  d->is_opened = true;
+
+  auto min_message_id = MessageId(ServerMessageId(1)).get();
+  if (d->last_message_id == MessageId() && d->last_read_outbox_message_id.get() < min_message_id &&
+      d->messages != nullptr && d->messages->message_id.get() < min_message_id) {
+    Message *m = d->messages.get();
+    while (m->right != nullptr) {
+      m = m->right.get();
+    }
+    if (m->message_id.get() < min_message_id) {
+      read_history_inbox(d->dialog_id, m->message_id, -1, "open_dialog");
+    }
+  }
+
+  LOG(INFO) << "Cancel unload timeout for " << d->dialog_id;
+  pending_unload_dialog_timeout_.cancel_timeout(d->dialog_id.get());
+
+  switch (d->dialog_id.get_type()) {
+    case DialogType::User:
+      break;
+    case DialogType::Chat: {
+      auto chat_id = d->dialog_id.get_chat_id();
+      td_->contacts_manager_->get_chat_full(chat_id, Promise<Unit>());
+      break;
+    }
+    case DialogType::Channel:
+      get_channel_difference(d->dialog_id, d->pts, true, "open_dialog");
+      break;
+    case DialogType::SecretChat:
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+}
+
+void MessagesManager::close_dialog(Dialog *d) {
+  if (!d->is_opened) {
+    return;
+  }
+  d->is_opened = false;
+
+  if (have_input_peer(d->dialog_id, AccessRights::Write)) {
+    if (pending_draft_message_timeout_.has_timeout(d->dialog_id.get())) {
+      pending_draft_message_timeout_.set_timeout_in(d->dialog_id.get(), 0.0);
+    }
+  } else {
+    pending_draft_message_timeout_.cancel_timeout(d->dialog_id.get());
+  }
+
+  if (have_input_peer(d->dialog_id, AccessRights::Read)) {
+    if (pending_message_views_timeout_.has_timeout(d->dialog_id.get())) {
+      pending_message_views_timeout_.set_timeout_in(d->dialog_id.get(), 0.0);
+    }
+  } else {
+    pending_message_views_timeout_.cancel_timeout(d->dialog_id.get());
+    d->pending_viewed_message_ids.clear();
+    d->increment_view_counter = false;
+  }
+
+  if (is_message_unload_enabled()) {
+    LOG(INFO) << "Schedule unload of " << d->dialog_id;
+    pending_unload_dialog_timeout_.set_timeout_in(d->dialog_id.get(), DIALOG_UNLOAD_DELAY);
+  }
+
+  switch (d->dialog_id.get_type()) {
+    case DialogType::User:
+      break;
+    case DialogType::Chat:
+      break;
+    case DialogType::Channel:
+      channel_get_difference_timeout_.cancel_timeout(d->dialog_id.get());
+      break;
+    case DialogType::SecretChat:
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+}
+
+tl_object_ptr<td_api::inputMessageText> MessagesManager::get_input_message_text_object(
+    const InputMessageText &input_message_text) const {
+  return make_tl_object<td_api::inputMessageText>(get_formatted_text_object(input_message_text.text),
+                                                  input_message_text.disable_web_page_preview,
+                                                  input_message_text.clear_draft);
+}
+
+tl_object_ptr<td_api::draftMessage> MessagesManager::get_draft_message_object(
+    const unique_ptr<DraftMessage> &draft_message) const {
+  if (draft_message == nullptr) {
+    return nullptr;
+  }
+  return make_tl_object<td_api::draftMessage>(draft_message->reply_to_message_id.get(),
+                                              get_input_message_text_object(draft_message->input_message_text));
+}
+
+tl_object_ptr<td_api::ChatType> MessagesManager::get_chat_type_object(DialogId dialog_id) const {
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      return make_tl_object<td_api::chatTypePrivate>(
+          td_->contacts_manager_->get_user_id_object(dialog_id.get_user_id(), "chatTypePrivate"));
+    case DialogType::Chat:
+      return make_tl_object<td_api::chatTypeBasicGroup>(
+          td_->contacts_manager_->get_basic_group_id_object(dialog_id.get_chat_id(), "chatTypeBasicGroup"));
+    case DialogType::Channel: {
+      auto channel_id = dialog_id.get_channel_id();
+      auto channel_type = td_->contacts_manager_->get_channel_type(channel_id);
+      return make_tl_object<td_api::chatTypeSupergroup>(
+          td_->contacts_manager_->get_supergroup_id_object(channel_id, "chatTypeSupergroup"),
+          channel_type != ChannelType::Megagroup);
+    }
+    case DialogType::SecretChat: {
+      auto secret_chat_id = dialog_id.get_secret_chat_id();
+      auto user_id = td_->contacts_manager_->get_secret_chat_user_id(secret_chat_id);
+      return make_tl_object<td_api::chatTypeSecret>(
+          td_->contacts_manager_->get_secret_chat_id_object(secret_chat_id, "chatTypeSecret"),
+          td_->contacts_manager_->get_user_id_object(user_id, "chatTypeSecret"));
+    }
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+tl_object_ptr<td_api::chat> MessagesManager::get_chat_object(const Dialog *d) {
+  if (!td_->auth_manager_->is_bot()) {
+    if (d->last_new_message_id.is_valid()) {
+      // if (preloaded_dialogs_++ < 0) {
+      //   preload_older_messages(d, d->last_new_message_id);
+      // }
+    }
+    if (!d->notification_settings.is_synchronized && d->dialog_id.get_type() != DialogType::SecretChat &&
+        have_input_peer(d->dialog_id, AccessRights::Read)) {
+      // asynchronously get dialog from the server
+      send_get_dialog_query(d->dialog_id, Auto());
+    }
+  }
+
+  return make_tl_object<td_api::chat>(
+      d->dialog_id.get(), get_chat_type_object(d->dialog_id), get_dialog_title(d->dialog_id),
+      get_chat_photo_object(td_->file_manager_.get(), get_dialog_photo(d->dialog_id)),
+      get_message_object(d->dialog_id, get_message(d, d->last_message_id)),
+      DialogDate(d->order, d->dialog_id) <= last_dialog_date_ ? d->order : 0, d->pinned_order != DEFAULT_ORDER,
+      can_report_dialog(d->dialog_id), d->server_unread_count + d->local_unread_count,
+      d->last_read_inbox_message_id.get(), d->last_read_outbox_message_id.get(), d->unread_mention_count,
+      get_notification_settings_object(&d->notification_settings), d->reply_markup_message_id.get(),
+      get_draft_message_object(d->draft_message), d->client_data);
+}
+
+tl_object_ptr<td_api::chat> MessagesManager::get_chat_object(DialogId dialog_id) {
+  auto d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+  return get_chat_object(d);
+}
+
+tl_object_ptr<td_api::chats> MessagesManager::get_chats_object(const vector<DialogId> &dialogs) {
+  return td_api::make_object<td_api::chats>(transform(dialogs, [](DialogId dialog_id) { return dialog_id.get(); }));
+}
+
+tl_object_ptr<td_api::NotificationSettingsScope> MessagesManager::get_notification_settings_scope_object(
+    NotificationSettingsScope scope) {
+  switch (scope) {
+    case NOTIFICATION_SETTINGS_FOR_PRIVATE_CHATS:
+      return make_tl_object<td_api::notificationSettingsScopePrivateChats>();
+    case NOTIFICATION_SETTINGS_FOR_GROUP_CHATS:
+      return make_tl_object<td_api::notificationSettingsScopeBasicGroupChats>();
+    case NOTIFICATION_SETTINGS_FOR_ALL_CHATS:
+      return make_tl_object<td_api::notificationSettingsScopeAllChats>();
+    default:
+      return make_tl_object<td_api::notificationSettingsScopeChat>(scope);
+  }
+}
+
+tl_object_ptr<td_api::notificationSettings> MessagesManager::get_notification_settings_object(
+    const NotificationSettings *notification_settings) {
+  return make_tl_object<td_api::notificationSettings>(max(0, notification_settings->mute_until - G()->unix_time()),
+                                                      notification_settings->sound,
+                                                      notification_settings->show_preview);
+}
+
+const NotificationSettings *MessagesManager::get_dialog_notification_settings(const Dialog *d,
+                                                                              DialogId dialog_id) const {
+  if (d != nullptr &&
+      d->notification_settings.is_synchronized) {  // TODO this is wrong check for initialized notification settings
+    return &d->notification_settings;
+  }
+
+  const NotificationSettings *notification_settings = nullptr;
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::SecretChat:
+      notification_settings = &users_notification_settings_;
+      break;
+    case DialogType::Chat:
+      notification_settings = &chats_notification_settings_;
+      break;
+    case DialogType::Channel: {
+      ChannelId channel_id = dialog_id.get_channel_id();
+      auto channel_type = td_->contacts_manager_->get_channel_type(channel_id);
+      if (channel_type == ChannelType::Megagroup) {
+        return nullptr;
+      }
+      notification_settings = &chats_notification_settings_;
+      break;
+    }
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+  if (notification_settings->is_synchronized) {
+    return notification_settings;
+  }
+  return &dialogs_notification_settings_;
+}
+
+const NotificationSettings *MessagesManager::get_notification_settings(NotificationSettingsScope scope,
+                                                                       Promise<Unit> &&promise) {
+  const NotificationSettings *notification_settings = get_notification_settings(scope, true);
+  if (notification_settings == nullptr) {
+    promise.set_error(Status::Error(3, "Chat not found"));
+    return nullptr;
+  }
+
+  if (!notification_settings->is_synchronized && get_notification_settings(scope, false) != nullptr &&
+      !td_->auth_manager_->is_bot()) {
+    td_->create_handler<GetNotifySettingsQuery>(std::move(promise))->send(scope);
+    return nullptr;
+  }
+
+  promise.set_value(Unit());
+  return notification_settings;
+}
+
+NotificationSettings *MessagesManager::get_notification_settings(NotificationSettingsScope scope, bool force) {
+  switch (scope) {
+    case NOTIFICATION_SETTINGS_FOR_PRIVATE_CHATS:
+      return &users_notification_settings_;
+    case NOTIFICATION_SETTINGS_FOR_GROUP_CHATS:
+      return &chats_notification_settings_;
+    case NOTIFICATION_SETTINGS_FOR_ALL_CHATS:
+      return &dialogs_notification_settings_;
+    default: {
+      DialogId dialog_id(scope);
+      auto dialog = get_dialog_force(dialog_id);
+      if (dialog == nullptr) {
+        return nullptr;
+      }
+      if (!force && !have_input_peer(dialog_id, AccessRights::Read)) {
+        return nullptr;
+      }
+      return &dialog->notification_settings;
+    }
+  }
+}
+
+tl_object_ptr<telegram_api::InputNotifyPeer> MessagesManager::get_input_notify_peer(
+    NotificationSettingsScope scope) const {
+  switch (scope) {
+    case NOTIFICATION_SETTINGS_FOR_PRIVATE_CHATS:
+      return make_tl_object<telegram_api::inputNotifyUsers>();
+    case NOTIFICATION_SETTINGS_FOR_GROUP_CHATS:
+      return make_tl_object<telegram_api::inputNotifyChats>();
+    case NOTIFICATION_SETTINGS_FOR_ALL_CHATS:
+      return make_tl_object<telegram_api::inputNotifyAll>();
+    default: {
+      DialogId dialog_id(scope);
+      if (get_dialog(dialog_id) == nullptr) {
+        return nullptr;
+      }
+      auto input_peer = get_input_peer(dialog_id, AccessRights::Read);
+      if (input_peer == nullptr) {
+        return nullptr;
+      }
+      return make_tl_object<telegram_api::inputNotifyPeer>(std::move(input_peer));
+    }
+  }
+}
+
+Status MessagesManager::set_notification_settings(NotificationSettingsScope scope,
+                                                  tl_object_ptr<td_api::notificationSettings> &&notification_settings) {
+  if (notification_settings == nullptr) {
+    return Status::Error(400, "New notification settings must not be empty");
+  }
+  if (!clean_input_string(notification_settings->sound_)) {
+    return Status::Error(400, "Notification settings sound must be encoded in UTF-8");
+  }
+
+  auto current_settings = get_notification_settings(scope, false);
+  if (current_settings == nullptr) {
+    return Status::Error(6, "Wrong chat identifier specified");
+  }
+
+  int32 current_time = G()->unix_time();
+  if (notification_settings->mute_for_ > std::numeric_limits<int32>::max() - current_time) {
+    notification_settings->mute_for_ = std::numeric_limits<int32>::max() - current_time;
+  }
+
+  int32 mute_until;
+  if (notification_settings->mute_for_ <= 0) {
+    mute_until = 0;
+  } else {
+    mute_until = notification_settings->mute_for_ + current_time;
+  }
+
+  NotificationSettings new_settings(mute_until, std::move(notification_settings->sound_),
+                                    notification_settings->show_preview_, current_settings->silent_send_message);
+
+  if (update_notification_settings(scope, current_settings, new_settings)) {
+    td_->create_handler<UpdateNotifySettingsQuery>()->send(scope, new_settings);
+  }
+  return Status::OK();
+}
+
+void MessagesManager::reset_all_notification_settings() {
+  NotificationSettings new_settings(0, "default", true, false);
+  NotificationSettings new_megagroup_settings(std::numeric_limits<int32>::max(), "default", true, false);
+
+  update_notification_settings(NOTIFICATION_SETTINGS_FOR_PRIVATE_CHATS, &users_notification_settings_, new_settings);
+  update_notification_settings(NOTIFICATION_SETTINGS_FOR_GROUP_CHATS, &chats_notification_settings_, new_settings);
+  update_notification_settings(NOTIFICATION_SETTINGS_FOR_ALL_CHATS, &dialogs_notification_settings_, new_settings);
+
+  for (auto &dialog : dialogs_) {
+    Dialog *d = dialog.second.get();
+    auto dialog_id = d->dialog_id;
+    bool is_megagroup = dialog_id.get_type() == DialogType::Channel &&
+                        td_->contacts_manager_->get_channel_type(dialog_id.get_channel_id()) == ChannelType::Megagroup;
+
+    if (is_megagroup) {
+      update_notification_settings(NotificationSettingsScope(dialog_id.get()), &d->notification_settings,
+                                   new_megagroup_settings);
+    } else {
+      update_notification_settings(NotificationSettingsScope(dialog_id.get()), &d->notification_settings, new_settings);
+    }
+  }
+  td_->create_handler<ResetNotifySettingsQuery>()->send();
+}
+
+unique_ptr<DraftMessage> MessagesManager::get_draft_message(
+    ContactsManager *contacts_manager, tl_object_ptr<telegram_api::DraftMessage> &&draft_message_ptr) {
+  if (draft_message_ptr == nullptr) {
+    return nullptr;
+  }
+  auto constructor_id = draft_message_ptr->get_id();
+  switch (constructor_id) {
+    case telegram_api::draftMessageEmpty::ID:
+      return nullptr;
+    case telegram_api::draftMessage::ID: {
+      auto draft = move_tl_object_as<telegram_api::draftMessage>(draft_message_ptr);
+      auto flags = draft->flags_;
+      auto result = make_unique<DraftMessage>();
+      result->date = draft->date_;
+      if ((flags & SEND_MESSAGE_FLAG_IS_REPLY) != 0) {
+        result->reply_to_message_id = MessageId(ServerMessageId(draft->reply_to_msg_id_));
+        if (!result->reply_to_message_id.is_valid()) {
+          LOG(ERROR) << "Receive " << result->reply_to_message_id << " as reply_to_message_id in the draft";
+          result->reply_to_message_id = MessageId();
+        }
+      }
+
+      auto entities = get_message_entities(contacts_manager, std::move(draft->entities_), "draftMessage");
+      auto status = fix_formatted_text(draft->message_, entities, true, true, true, true);
+      if (status.is_error()) {
+        LOG(ERROR) << "Receive error " << status << " while parsing draft " << draft->message_;
+        if (!clean_input_string(draft->message_)) {
+          draft->message_.clear();
+        }
+        entities.clear();
+      }
+      result->input_message_text.text = FormattedText{std::move(draft->message_), std::move(entities)};
+      result->input_message_text.disable_web_page_preview = (flags & SEND_MESSAGE_FLAG_DISABLE_WEB_PAGE_PREVIEW) != 0;
+      result->input_message_text.clear_draft = false;
+
+      return result;
+    }
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+tl_object_ptr<td_api::messages> MessagesManager::get_dialog_history(DialogId dialog_id, MessageId from_message_id,
+                                                                    int32 offset, int32 limit, int left_tries,
+                                                                    bool only_local, Promise<Unit> &&promise) {
+  if (limit <= 0) {
+    promise.set_error(Status::Error(3, "Parameter limit must be positive"));
+    return nullptr;
+  }
+  if (limit > MAX_GET_HISTORY) {
+    limit = MAX_GET_HISTORY;
+  }
+  if (limit <= -offset) {
+    promise.set_error(Status::Error(5, "Parameter limit must be greater than -offset"));
+    return nullptr;
+  }
+  if (offset > 0) {
+    promise.set_error(Status::Error(5, "Parameter offset must be non-positive"));
+    return nullptr;
+  }
+
+  if (from_message_id == MessageId() || from_message_id.get() > MessageId::max().get()) {
+    from_message_id = MessageId::max();
+  }
+  if (!from_message_id.is_valid()) {
+    promise.set_error(Status::Error(3, "Invalid value of parameter from_message_id specified"));
+    return nullptr;
+  }
+
+  const Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    promise.set_error(Status::Error(6, "Chat not found"));
+    return nullptr;
+  }
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    promise.set_error(Status::Error(5, "Can't access the chat"));
+    return nullptr;
+  }
+
+  LOG(INFO) << "Get " << (only_local ? "local " : "") << "history in " << dialog_id << " from " << from_message_id
+            << " with offset " << offset << " and limit " << limit << ", " << left_tries
+            << " tries left. Last read inbox message is " << d->last_read_inbox_message_id
+            << ", last read outbox message is " << d->last_read_outbox_message_id
+            << ", have_full_history = " << d->have_full_history;
+
+  MessagesConstIterator p(d, from_message_id);
+  LOG(DEBUG) << "Iterator points to " << (*p ? (*p)->message_id : MessageId());
+  bool from_the_end = (d->last_message_id != MessageId() && from_message_id.get() > d->last_message_id.get()) ||
+                      from_message_id.get() >= MessageId::max().get();
+
+  if (from_the_end) {
+    limit += offset;
+    offset = 0;
+    if (d->last_message_id == MessageId()) {
+      p = MessagesConstIterator();
+    }
+  } else {
+    bool have_a_gap = false;
+    if (*p == nullptr) {
+      // there is no gap if from_message_id is less than first message in the dialog
+      if (left_tries == 0 && d->messages != nullptr && offset < 0) {
+        Message *cur = d->messages.get();
+        while (cur->left != nullptr) {
+          cur = cur->left.get();
+        }
+        CHECK(cur->message_id.get() > from_message_id.get());
+        from_message_id = cur->message_id;
+        p = MessagesConstIterator(d, from_message_id);
+      } else {
+        have_a_gap = true;
+      }
+    } else if ((*p)->message_id != from_message_id) {
+      CHECK((*p)->message_id.get() < from_message_id.get());
+      if (!(*p)->have_next &&
+          (d->last_message_id == MessageId() || (*p)->message_id.get() < d->last_message_id.get())) {
+        have_a_gap = true;
+      }
+    }
+
+    if (have_a_gap) {
+      LOG(INFO) << "Have a gap near message to get chat history from";
+      p = MessagesConstIterator();
+    }
+    if (*p != nullptr && (*p)->message_id == from_message_id) {
+      if (offset < 0) {
+        offset++;
+      } else {
+        --p;
+      }
+    }
+
+    while (*p != nullptr && offset < 0) {
+      ++p;
+      if (*p) {
+        ++offset;
+        from_message_id = (*p)->message_id;
+      }
+    }
+
+    if (offset < 0 && ((d->last_message_id != MessageId() && from_message_id.get() >= d->last_message_id.get()) ||
+                       (!have_a_gap && left_tries == 0))) {
+      CHECK(!have_a_gap);
+      limit += offset;
+      offset = 0;
+      p = MessagesConstIterator(d, from_message_id);
+    }
+
+    if (!have_a_gap && offset < 0) {
+      offset--;
+    }
+  }
+
+  LOG(INFO) << "Iterator after applying offset points to " << (*p ? (*p)->message_id : MessageId())
+            << ", offset = " << offset << ", limit = " << limit << ", from_the_end = " << from_the_end;
+  vector<tl_object_ptr<td_api::message>> messages;
+  if (*p != nullptr && offset == 0) {
+    while (*p != nullptr && limit-- > 0) {
+      messages.push_back(get_message_object(dialog_id, *p));
+      from_message_id = (*p)->message_id;
+      --p;
+    }
+  }
+
+  if (messages.size()) {
+    // maybe need some messages
+    CHECK(offset == 0);
+    preload_newer_messages(d, MessageId(messages[0]->id_));
+    preload_older_messages(d, MessageId(messages.back()->id_));
+  } else if (limit > 0 && (/*d->first_remote_message_id != -1 && */ left_tries != 0)) {
+    // there can be more messages on the server, need to load them
+    if (from_the_end) {
+      from_message_id = MessageId();
+    }
+    send_closure_later(actor_id(this), &MessagesManager::load_messages, d->dialog_id, from_message_id, offset, limit,
+                       left_tries, only_local, std::move(promise));
+    return nullptr;
+  }
+
+  LOG(INFO) << "Return " << messages.size() << " messages in result to getChatHistory";
+  promise.set_value(Unit());                            // can send some messages
+  return get_messages_object(-1, std::move(messages));  // TODO return real total_count of messages in the dialog
+}
+
+class MessagesManager::ReadHistoryOnServerLogEvent {
+ public:
+  DialogId dialog_id_;
+  MessageId max_message_id_;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(dialog_id_, storer);
+    td::store(max_message_id_, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(dialog_id_, parser);
+    td::parse(max_message_id_, parser);
+  }
+};
+
+void MessagesManager::read_history_on_server(DialogId dialog_id, MessageId max_message_id, bool allow_error,
+                                             uint64 logevent_id) {
+  if (td_->auth_manager_->is_bot()) {
+    return;
+  }
+  LOG(INFO) << "Read history in " << dialog_id << " on server up to " << max_message_id;
+
+  if (logevent_id == 0 && G()->parameters().use_message_db) {
+    ReadHistoryOnServerLogEvent logevent;
+    logevent.dialog_id_ = dialog_id;
+    logevent.max_message_id_ = max_message_id;
+
+    auto storer = LogEventStorerImpl<ReadHistoryOnServerLogEvent>(logevent);
+    logevent_id = BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::ReadHistoryOnServer, storer);
+  }
+
+  Promise<> promise;
+  if (logevent_id != 0) {
+    promise = PromiseCreator::lambda([logevent_id](Result<Unit> result) mutable {
+      if (!G()->close_flag()) {
+        BinlogHelper::erase(G()->td_db()->get_binlog(), logevent_id);
+      }
+    });
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+      td_->create_handler<ReadHistoryQuery>(std::move(promise))->send(dialog_id, max_message_id);
+      break;
+    case DialogType::Channel: {
+      auto channel_id = dialog_id.get_channel_id();
+      td_->create_handler<ReadChannelHistoryQuery>(std::move(promise))->send(channel_id, max_message_id, allow_error);
+      break;
+    }
+    case DialogType::SecretChat: {
+      auto secret_chat_id = dialog_id.get_secret_chat_id();
+      auto *message = get_message_force(FullMessageId(dialog_id, max_message_id));
+      if (message != nullptr) {
+        send_closure(G()->secret_chats_manager(), &SecretChatsManager::send_read_history, secret_chat_id, message->date,
+                     std::move(promise));
+      }
+      break;
+    }
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+}
+
+std::pair<int32, vector<MessageId>> MessagesManager::search_dialog_messages(
+    DialogId dialog_id, const string &query, UserId sender_user_id, MessageId from_message_id, int32 offset,
+    int32 limit, const tl_object_ptr<td_api::SearchMessagesFilter> &filter, int64 &random_id, bool use_db,
+    Promise<Unit> &&promise) {
+  if (random_id != 0) {
+    // request has already been sent before
+    auto it = found_dialog_messages_.find(random_id);
+    if (it != found_dialog_messages_.end()) {
+      auto result = std::move(it->second);
+      found_dialog_messages_.erase(it);
+      promise.set_value(Unit());
+      return result;
+    }
+    random_id = 0;
+  }
+  LOG(INFO) << "Search messages with query \"" << query << "\" in " << dialog_id << " sent by " << sender_user_id
+            << " filtered by " << to_string(filter) << " from " << from_message_id << " with offset " << offset
+            << " and limit " << limit;
+
+  std::pair<int32, vector<MessageId>> result;
+  if (limit <= 0) {
+    promise.set_error(Status::Error(3, "Parameter limit must be positive"));
+    return result;
+  }
+  if (limit > MAX_SEARCH_MESSAGES) {
+    limit = MAX_SEARCH_MESSAGES;
+  }
+  if (limit <= -offset) {
+    promise.set_error(Status::Error(5, "Parameter limit must be greater than -offset"));
+    return result;
+  }
+  if (offset > 0) {
+    promise.set_error(Status::Error(5, "Parameter offset must be non-positive"));
+    return result;
+  }
+
+  if (from_message_id.get() > MessageId::max().get()) {
+    from_message_id = MessageId::max();
+  }
+
+  if (!from_message_id.is_valid() && from_message_id != MessageId()) {
+    promise.set_error(Status::Error(3, "Parameter from_message_id must be identifier of the chat message or 0"));
+    return result;
+  }
+  from_message_id = from_message_id.get_next_server_message_id();
+
+  const Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    promise.set_error(Status::Error(6, "Chat not found"));
+    return result;
+  }
+
+  auto input_user = td_->contacts_manager_->get_input_user(sender_user_id);
+  if (sender_user_id.is_valid() && input_user == nullptr) {
+    promise.set_error(Status::Error(6, "Wrong sender user identifier specified"));
+    return result;
+  }
+
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 || found_dialog_messages_.find(random_id) != found_dialog_messages_.end());
+  found_dialog_messages_[random_id];  // reserve place for result
+
+  auto filter_type = get_search_messages_filter(filter);
+  if (filter_type == SearchMessagesFilter::UnreadMention) {
+    if (!query.empty()) {
+      promise.set_error(Status::Error(6, "Non-empty query is unsupported with the specified filter"));
+      return result;
+    }
+    if (input_user != nullptr) {
+      promise.set_error(Status::Error(6, "Non-empty sender user is unsupported with the specified filter"));
+      return result;
+    }
+  }
+
+  // Trying to use database
+  if (query.empty() && G()->parameters().use_message_db && filter_type != SearchMessagesFilter::Empty &&
+      input_user == nullptr) {  // TODO support filter by users in the database
+    MessageId first_db_message_id = get_first_database_message_id_by_index(d, filter_type);
+    int32 message_count = d->message_count_by_index[search_messages_filter_index(filter_type)];
+    auto fixed_from_message_id = from_message_id;
+    if (fixed_from_message_id == MessageId()) {
+      fixed_from_message_id = MessageId::max();
+    }
+    LOG(INFO) << "Search messages in " << dialog_id << " from " << fixed_from_message_id << ", have up to "
+              << first_db_message_id << ", message_count = " << message_count;
+    if (use_db &&
+        (first_db_message_id.get() < fixed_from_message_id.get() ||
+         (first_db_message_id.get() == fixed_from_message_id.get() && offset < 0)) &&
+        message_count != -1) {
+      LOG(INFO) << "Search messages in database in " << dialog_id << " from " << fixed_from_message_id
+                << " and with limit " << limit;
+      auto new_promise = PromiseCreator::lambda(
+          [random_id, dialog_id, fixed_from_message_id, first_db_message_id, filter_type, offset, limit,
+           promise = std::move(promise)](Result<MessagesDbMessagesResult> result) mutable {
+            send_closure(G()->messages_manager(), &MessagesManager::on_search_dialog_messages_db_result, random_id,
+                         dialog_id, fixed_from_message_id, first_db_message_id, filter_type, offset, limit,
+                         std::move(result), std::move(promise));
+          });
+      MessagesDbMessagesQuery db_query;
+      db_query.dialog_id = dialog_id;
+      db_query.index_mask = search_messages_filter_index_mask(filter_type);
+      db_query.from_message_id = fixed_from_message_id;
+      db_query.offset = offset;
+      db_query.limit = limit;
+      G()->td_db()->get_messages_db_async()->get_messages(db_query, std::move(new_promise));
+      return result;
+    }
+  }
+
+  LOG(DEBUG) << "Search messages on server in " << dialog_id << " with query \"" << query << "\" from user "
+             << sender_user_id << " from " << from_message_id << " and with limit " << limit;
+
+  switch (dialog_id.get_type()) {
+    case DialogType::None:
+    case DialogType::User:
+    case DialogType::Chat:
+    case DialogType::Channel:
+      td_->create_handler<SearchMessagesQuery>(std::move(promise))
+          ->send(dialog_id, query, sender_user_id, std::move(input_user), from_message_id, offset, limit, filter_type,
+                 random_id);
+      break;
+    case DialogType::SecretChat:
+      if (filter_type == SearchMessagesFilter::UnreadMention) {
+        promise.set_value(Unit());
+      } else {
+        promise.set_error(Status::Error(500, "Search messages in secret chats is not supported"));
+      }
+      break;
+    default:
+      UNREACHABLE();
+      promise.set_error(Status::Error(500, "Search messages is not supported"));
+  }
+  return result;
+}
+
+std::pair<int32, vector<FullMessageId>> MessagesManager::search_call_messages(MessageId from_message_id, int32 limit,
+                                                                              bool only_missed, int64 &random_id,
+                                                                              bool use_db, Promise<Unit> &&promise) {
+  if (random_id != 0) {
+    // request has already been sent before
+    auto it = found_call_messages_.find(random_id);
+    if (it != found_call_messages_.end()) {
+      auto result = std::move(it->second);
+      found_call_messages_.erase(it);
+      promise.set_value(Unit());
+      return result;
+    }
+    random_id = 0;
+  }
+  LOG(INFO) << "Search call messages from " << from_message_id << " with limit " << limit;
+
+  std::pair<int32, vector<FullMessageId>> result;
+  if (limit <= 0) {
+    promise.set_error(Status::Error(3, "Parameter limit must be positive"));
+    return result;
+  }
+  if (limit > MAX_SEARCH_MESSAGES) {
+    limit = MAX_SEARCH_MESSAGES;
+  }
+
+  if (from_message_id.get() > MessageId::max().get()) {
+    from_message_id = MessageId::max();
+  }
+
+  if (!from_message_id.is_valid() && from_message_id != MessageId()) {
+    promise.set_error(Status::Error(3, "Parameter from_message_id must be identifier of the chat message or 0"));
+    return result;
+  }
+  from_message_id = from_message_id.get_next_server_message_id();
+
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 || found_call_messages_.find(random_id) != found_call_messages_.end());
+  found_call_messages_[random_id];  // reserve place for result
+
+  auto filter_type = only_missed ? SearchMessagesFilter::MissedCall : SearchMessagesFilter::Call;
+
+  // Try to use database
+  MessageId first_db_message_id =
+      calls_db_state_.first_calls_database_message_id_by_index[search_calls_filter_index(filter_type)];
+  int32 message_count = calls_db_state_.message_count_by_index[search_calls_filter_index(filter_type)];
+  auto fixed_from_message_id = from_message_id;
+  if (fixed_from_message_id == MessageId()) {
+    fixed_from_message_id = MessageId::max();
+  }
+  CHECK(fixed_from_message_id.is_valid() && fixed_from_message_id.is_server());
+  LOG(INFO) << "Search call messages from " << fixed_from_message_id << ", have up to " << first_db_message_id
+            << ", message_count = " << message_count;
+  if (use_db && first_db_message_id.get() < fixed_from_message_id.get() && message_count != -1) {
+    LOG(INFO) << "Search messages in database from " << fixed_from_message_id << " and with limit " << limit;
+
+    MessagesDbCallsQuery db_query;
+    db_query.index_mask = search_messages_filter_index_mask(filter_type);
+    db_query.from_unique_message_id = fixed_from_message_id.get_server_message_id().get();
+    db_query.limit = limit;
+    G()->td_db()->get_messages_db_async()->get_calls(
+        db_query, PromiseCreator::lambda([random_id, first_db_message_id, filter_type, promise = std::move(promise)](
+                                             Result<MessagesDbCallsResult> calls_result) mutable {
+          send_closure(G()->messages_manager(), &MessagesManager::on_messages_db_calls_result, std::move(calls_result),
+                       random_id, first_db_message_id, filter_type, std::move(promise));
+        }));
+    return result;
+  }
+
+  LOG(DEBUG) << "Search call messages on server from " << from_message_id << " and with limit " << limit;
+  td_->create_handler<SearchMessagesQuery>(std::move(promise))
+      ->send(DialogId(), "", UserId(), nullptr, from_message_id, 0, limit, filter_type, random_id);
+  return result;
+}
+
+std::pair<int32, vector<MessageId>> MessagesManager::search_dialog_recent_location_messages(DialogId dialog_id,
+                                                                                            int32 limit,
+                                                                                            int64 &random_id,
+                                                                                            Promise<Unit> &&promise) {
+  if (random_id != 0) {
+    // request has already been sent before
+    auto it = found_dialog_recent_location_messages_.find(random_id);
+    CHECK(it != found_dialog_recent_location_messages_.end());
+    auto result = std::move(it->second);
+    found_dialog_recent_location_messages_.erase(it);
+    promise.set_value(Unit());
+    return result;
+  }
+  LOG(INFO) << "Search recent location messages in " << dialog_id << " with limit " << limit;
+
+  std::pair<int32, vector<MessageId>> result;
+  if (limit <= 0) {
+    promise.set_error(Status::Error(3, "Parameter limit must be positive"));
+    return result;
+  }
+  if (limit > MAX_SEARCH_MESSAGES) {
+    limit = MAX_SEARCH_MESSAGES;
+  }
+
+  const Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    promise.set_error(Status::Error(6, "Chat not found"));
+    return result;
+  }
+
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 ||
+           found_dialog_recent_location_messages_.find(random_id) != found_dialog_recent_location_messages_.end());
+  found_dialog_recent_location_messages_[random_id];  // reserve place for result
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+    case DialogType::Channel:
+      td_->create_handler<GetRecentLocationsQuery>(std::move(promise))->send(dialog_id, limit, random_id);
+      break;
+    case DialogType::SecretChat:
+      promise.set_value(Unit());
+      break;
+    default:
+      UNREACHABLE();
+      promise.set_error(Status::Error(500, "Search messages is not supported"));
+  }
+  return result;
+}
+
+vector<FullMessageId> MessagesManager::get_active_live_location_messages(Promise<Unit> &&promise) {
+  if (!G()->parameters().use_message_db) {
+    are_active_live_location_messages_loaded_ = true;
+  }
+
+  if (!are_active_live_location_messages_loaded_) {
+    load_active_live_location_messages_queries_.push_back(std::move(promise));
+    if (load_active_live_location_messages_queries_.size() == 1u) {
+      LOG(INFO) << "Trying to load active live location messages from database";
+      G()->td_db()->get_sqlite_pmc()->get(
+          "di_active_live_location_messages", PromiseCreator::lambda([](string value) {
+            send_closure(G()->messages_manager(),
+                         &MessagesManager::on_load_active_live_location_full_message_ids_from_database,
+                         std::move(value));
+          }));
+    }
+    return {};
+  }
+
+  promise.set_value(Unit());
+  vector<FullMessageId> result;
+  for (auto &full_message_id : active_live_location_full_message_ids_) {
+    auto m = get_message(full_message_id);
+    CHECK(m != nullptr);
+    CHECK(m->content->get_id() == MessageLiveLocation::ID);
+
+    auto live_period = static_cast<const MessageLiveLocation *>(m->content.get())->period;
+    if (live_period <= G()->unix_time() - m->date) {  // bool is_expired flag?
+      // live location is expired
+      continue;
+    }
+    result.push_back(full_message_id);
+  }
+
+  return result;
+}
+
+void MessagesManager::on_load_active_live_location_full_message_ids_from_database(string value) {
+  if (value.empty()) {
+    LOG(INFO) << "Active live location messages aren't found in the database";
+    on_load_active_live_location_messages_finished();
+    return;
+  }
+
+  LOG(INFO) << "Successfully loaded active live location messages list of size " << value.size() << " from database";
+
+  auto new_full_message_ids = std::move(active_live_location_full_message_ids_);
+  vector<FullMessageId> old_full_message_ids;
+  log_event_parse(old_full_message_ids, value).ensure();
+
+  // TODO asynchronously load messages from database
+  active_live_location_full_message_ids_.clear();
+  for (auto full_message_id : old_full_message_ids) {
+    Message *m = get_message_force(full_message_id);
+    if (m != nullptr) {
+      try_add_active_live_location(full_message_id.get_dialog_id(), m);
+    }
+  }
+
+  for (auto full_message_id : new_full_message_ids) {
+    add_active_live_location(full_message_id);
+  }
+
+  on_load_active_live_location_messages_finished();
+
+  if (!new_full_message_ids.empty()) {
+    save_active_live_locations();
+  }
+}
+
+void MessagesManager::on_load_active_live_location_messages_finished() {
+  are_active_live_location_messages_loaded_ = true;
+  auto promises = std::move(load_active_live_location_messages_queries_);
+  load_active_live_location_messages_queries_.clear();
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+void MessagesManager::try_add_active_live_location(DialogId dialog_id, const Message *m) {
+  CHECK(m != nullptr);
+
+  if (m->content->get_id() != MessageLiveLocation::ID) {
+    return;
+  }
+
+  auto live_period = static_cast<const MessageLiveLocation *>(m->content.get())->period;
+  if (live_period <= G()->unix_time() - m->date + 1) {  // bool is_expired flag?
+    // live location is expired
+    return;
+  }
+  add_active_live_location({dialog_id, m->message_id});
+}
+
+void MessagesManager::add_active_live_location(FullMessageId full_message_id) {
+  if (!active_live_location_full_message_ids_.insert(full_message_id).second) {
+    return;
+  }
+
+  // TODO add timer for live location expiration
+
+  if (are_active_live_location_messages_loaded_) {
+    save_active_live_locations();
+  }
+}
+
+bool MessagesManager::delete_active_live_location(DialogId dialog_id, const Message *m) {
+  CHECK(m != nullptr);
+  return active_live_location_full_message_ids_.erase(FullMessageId{dialog_id, m->message_id}) != 0;
+}
+
+void MessagesManager::save_active_live_locations() {
+  CHECK(are_active_live_location_messages_loaded_);
+  LOG(INFO) << "Save active live locations of size " << active_live_location_full_message_ids_.size() << " to database";
+  if (G()->parameters().use_message_db) {
+    G()->td_db()->get_sqlite_pmc()->set("di_active_live_location_messages",
+                                        log_event_store(active_live_location_full_message_ids_).as_slice().str(),
+                                        Auto());
+  }
+}
+
+MessageId MessagesManager::get_first_database_message_id_by_index(const Dialog *d, SearchMessagesFilter filter) {
+  CHECK(d != nullptr);
+  auto message_id = filter == SearchMessagesFilter::Empty
+                        ? d->first_database_message_id
+                        : d->first_database_message_id_by_index[search_messages_filter_index(filter)];
+  if (!message_id.is_valid()) {
+    if (d->dialog_id.get_type() == DialogType::SecretChat) {
+      LOG(ERROR) << "Invalid first_database_message_id_by_index in " << d->dialog_id;
+      return MessageId::min();
+    }
+    return MessageId::max();
+  }
+  return message_id;
+}
+
+void MessagesManager::on_search_dialog_messages_db_result(int64 random_id, DialogId dialog_id,
+                                                          MessageId from_message_id, MessageId first_db_message_id,
+                                                          SearchMessagesFilter filter_type, int32 offset, int32 limit,
+                                                          Result<MessagesDbMessagesResult> result, Promise<> promise) {
+  if (result.is_error()) {
+    LOG(ERROR) << result.error();
+    if (first_db_message_id != MessageId::min() && dialog_id.get_type() != DialogType::SecretChat) {
+      found_dialog_messages_.erase(random_id);
+    }
+    return promise.set_value(Unit());
+  }
+
+  auto messages = result.move_as_ok().messages;
+
+  Dialog *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+
+  auto it = found_dialog_messages_.find(random_id);
+  CHECK(it != found_dialog_messages_.end());
+  auto &res = it->second.second;
+
+  res.reserve(messages.size());
+  for (auto &message : messages) {
+    auto m = on_get_message_from_database(dialog_id, d, message);
+    if (m != nullptr && first_db_message_id.get() <= m->message_id.get()) {
+      res.push_back(m->message_id);
+    }
+  }
+
+  auto &message_count = d->message_count_by_index[search_messages_filter_index(filter_type)];
+  int32 result_size = narrow_cast<int32>(res.size());
+  if ((message_count < result_size) ||
+      (from_message_id == MessageId::max() && first_db_message_id == MessageId::min() && message_count > result_size &&
+       result_size < limit + offset)) {
+    LOG(INFO) << "Fix found message count in " << dialog_id << " from " << message_count << " to " << result_size;
+    message_count = result_size;
+    if (filter_type == SearchMessagesFilter::UnreadMention) {
+      d->unread_mention_count = message_count;
+      send_update_chat_unread_mention_count(d);
+    }
+    on_dialog_updated(dialog_id, "on_search_dialog_messages_db_result");
+  }
+  it->second.first = message_count;
+  if (res.empty() && first_db_message_id != MessageId::min() && dialog_id.get_type() != DialogType::SecretChat) {
+    LOG(INFO) << "No messages in database found";
+    found_dialog_messages_.erase(it);
+  } else {
+    LOG(INFO) << "Found " << res.size() << " messages out of " << message_count << " in database";
+  }
+  promise.set_value(Unit());
+}
+
+std::pair<int64, vector<FullMessageId>> MessagesManager::offline_search_messages(
+    DialogId dialog_id, const string &query, int64 from_search_id, int32 limit,
+    const tl_object_ptr<td_api::SearchMessagesFilter> &filter, int64 &random_id, Promise<> &&promise) {
+  if (random_id != 0) {
+    // request has already been sent before
+    auto it = found_fts_messages_.find(random_id);
+    CHECK(it != found_fts_messages_.end());
+    auto result = std::move(it->second);
+    found_fts_messages_.erase(it);
+    promise.set_value(Unit());
+    return result;
+  }
+
+  if (query.empty()) {
+    promise.set_value(Unit());
+    return Auto();
+  }
+  if (dialog_id != DialogId() && !have_dialog_force(dialog_id)) {
+    promise.set_error(Status::Error(400, "Chat not found"));
+    return Auto();
+  }
+  if (limit <= 0) {
+    promise.set_error(Status::Error(400, "Limit must be positive"));
+    return Auto();
+  }
+  if (limit > MAX_SEARCH_MESSAGES) {
+    limit = MAX_SEARCH_MESSAGES;
+  }
+
+  MessagesDbFtsQuery fts_query;
+  fts_query.query = query;
+  fts_query.dialog_id = dialog_id;
+  fts_query.index_mask = search_messages_filter_index_mask(get_search_messages_filter(filter));
+  fts_query.from_search_id = from_search_id;
+  fts_query.limit = limit;
+
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 || found_fts_messages_.find(random_id) != found_fts_messages_.end());
+  found_fts_messages_[random_id];  // reserve place for result
+
+  G()->td_db()->get_messages_db_async()->get_messages_fts(
+      std::move(fts_query),
+      PromiseCreator::lambda([random_id, promise = std::move(promise)](Result<MessagesDbFtsResult> fts_result) mutable {
+        send_closure(G()->messages_manager(), &MessagesManager::on_messages_db_fts_result, std::move(fts_result),
+                     random_id, std::move(promise));
+      }));
+
+  return Auto();
+}
+
+void MessagesManager::on_messages_db_fts_result(Result<MessagesDbFtsResult> result, int64 random_id,
+                                                Promise<> &&promise) {
+  if (result.is_error()) {
+    found_fts_messages_.erase(random_id);
+    return promise.set_error(result.move_as_error());
+  }
+  auto fts_result = result.move_as_ok();
+
+  auto it = found_fts_messages_.find(random_id);
+  CHECK(it != found_fts_messages_.end());
+  auto &res = it->second.second;
+
+  res.reserve(fts_result.messages.size());
+  for (auto &message : fts_result.messages) {
+    auto m = on_get_message_from_database(message.dialog_id, get_dialog_force(message.dialog_id), message.data);
+    if (m != nullptr) {
+      res.push_back(FullMessageId(message.dialog_id, m->message_id));
+    }
+  }
+
+  it->second.first = fts_result.next_search_id;
+
+  promise.set_value(Unit());
+}
+
+void MessagesManager::on_messages_db_calls_result(Result<MessagesDbCallsResult> result, int64 random_id,
+                                                  MessageId first_db_message_id, SearchMessagesFilter filter,
+                                                  Promise<> &&promise) {
+  if (result.is_error()) {
+    found_call_messages_.erase(random_id);
+    return promise.set_error(result.move_as_error());
+  }
+  auto calls_result = result.move_as_ok();
+
+  auto it = found_call_messages_.find(random_id);
+  CHECK(it != found_call_messages_.end());
+  auto &res = it->second.second;
+
+  res.reserve(calls_result.messages.size());
+  for (auto &message : calls_result.messages) {
+    auto m = on_get_message_from_database(message.dialog_id, get_dialog_force(message.dialog_id), message.data);
+
+    if (m != nullptr && first_db_message_id.get() <= m->message_id.get()) {
+      res.push_back(FullMessageId(message.dialog_id, m->message_id));
+    }
+  }
+  it->second.first = calls_db_state_.message_count_by_index[search_calls_filter_index(filter)];
+
+  if (res.empty() && first_db_message_id != MessageId::min()) {
+    LOG(INFO) << "No messages in database found";
+    found_call_messages_.erase(it);
+  }
+
+  promise.set_value(Unit());
+}
+
+std::pair<int32, vector<FullMessageId>> MessagesManager::search_messages(const string &query, int32 offset_date,
+                                                                         DialogId offset_dialog_id,
+                                                                         MessageId offset_message_id, int32 limit,
+                                                                         int64 &random_id, Promise<Unit> &&promise) {
+  if (random_id != 0) {
+    // request has already been sent before
+    auto it = found_messages_.find(random_id);
+    CHECK(it != found_messages_.end());
+    auto result = std::move(it->second);
+    found_messages_.erase(it);
+    promise.set_value(Unit());
+    return result;
+  }
+
+  std::pair<int32, vector<FullMessageId>> result;
+  if (limit <= 0) {
+    promise.set_error(Status::Error(3, "Parameter limit must be positive"));
+    return result;
+  }
+  if (limit > MAX_SEARCH_MESSAGES) {
+    limit = MAX_SEARCH_MESSAGES;
+  }
+
+  if (offset_date <= 0) {
+    offset_date = std::numeric_limits<int32>::max();
+  }
+  if (!offset_message_id.is_valid()) {
+    offset_message_id = MessageId();
+  }
+  if (offset_message_id != MessageId() && !offset_message_id.is_server()) {
+    promise.set_error(
+        Status::Error(3, "Parameter offset_message_id must be identifier of the last found message or 0"));
+    return result;
+  }
+
+  if (query.empty()) {
+    promise.set_value(Unit());
+    return result;
+  }
+
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 || found_messages_.find(random_id) != found_messages_.end());
+  found_messages_[random_id];  // reserve place for result
+
+  LOG(DEBUG) << "Search messages globally with query = \"" << query << "\" from date " << offset_date << ", "
+             << offset_dialog_id << ", " << offset_message_id << " and with limit " << limit;
+
+  td_->create_handler<SearchMessagesGlobalQuery>(std::move(promise))
+      ->send(query, offset_date, offset_dialog_id, offset_message_id, limit, random_id);
+  return result;
+}
+
+int64 MessagesManager::get_dialog_message_by_date(DialogId dialog_id, int32 date, Promise<Unit> &&promise) {
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    promise.set_error(Status::Error(5, "Chat not found"));
+    return 0;
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    promise.set_error(Status::Error(5, "Can't access the chat"));
+    return 0;
+  }
+
+  if (date <= 0) {
+    date = 1;
+  }
+
+  int64 random_id = 0;
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 ||
+           get_dialog_message_by_date_results_.find(random_id) != get_dialog_message_by_date_results_.end());
+  get_dialog_message_by_date_results_[random_id];  // reserve place for result
+
+  auto message_id = find_message_by_date(d->messages, date);
+  if (message_id.is_valid() && (message_id == d->last_message_id || get_message(d, message_id)->have_next)) {
+    get_dialog_message_by_date_results_[random_id] = {dialog_id, message_id};
+    promise.set_value(Unit());
+    return random_id;
+  }
+
+  if (G()->parameters().use_message_db && d->last_database_message_id != MessageId()) {
+    CHECK(d->first_database_message_id != MessageId());
+    G()->td_db()->get_messages_db_async()->get_dialog_message_by_date(
+        dialog_id, d->first_database_message_id, d->last_database_message_id, date,
+        PromiseCreator::lambda([actor_id = actor_id(this), dialog_id, date, random_id,
+                                promise = std::move(promise)](Result<BufferSlice> result) mutable {
+          send_closure(actor_id, &MessagesManager::on_get_dialog_message_by_date_from_database, dialog_id, date,
+                       random_id, std::move(result), std::move(promise));
+        }));
+  } else {
+    get_dialog_message_by_date_from_server(d, date, random_id, false, std::move(promise));
+  }
+  return random_id;
+}
+
+MessageId MessagesManager::find_message_by_date(const unique_ptr<Message> &m, int32 date) {
+  if (m == nullptr) {
+    return MessageId();
+  }
+
+  if (m->date > date) {
+    return find_message_by_date(m->left, date);
+  }
+
+  auto message_id = find_message_by_date(m->right, date);
+  if (message_id.is_valid()) {
+    return message_id;
+  }
+
+  return m->message_id;
+}
+
+void MessagesManager::on_get_dialog_message_by_date_from_database(DialogId dialog_id, int32 date, int64 random_id,
+                                                                  Result<BufferSlice> result, Promise<Unit> promise) {
+  Dialog *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+  if (result.is_ok()) {
+    Message *m = on_get_message_from_database(dialog_id, d, result.ok());
+    if (m != nullptr) {
+      auto message_id = find_message_by_date(d->messages, date);
+      if (!message_id.is_valid()) {
+        LOG(ERROR) << "Failed to find " << m->message_id << " in " << dialog_id << " by date " << date;
+        message_id = m->message_id;
+      }
+      get_dialog_message_by_date_results_[random_id] = {dialog_id, message_id};
+      promise.set_value(Unit());
+      return;
+    }
+    // TODO if m == nullptr, we need to just adjust it to the next non-nullptr message, not get from server
+  }
+
+  return get_dialog_message_by_date_from_server(d, date, random_id, true, std::move(promise));
+}
+
+void MessagesManager::get_dialog_message_by_date_from_server(const Dialog *d, int32 date, int64 random_id,
+                                                             bool after_database_search, Promise<Unit> &&promise) {
+  CHECK(d != nullptr);
+  if (d->have_full_history) {
+    // request can be always done locally/in memory. There is no need to send request to the server
+    if (after_database_search) {
+      return promise.set_value(Unit());
+    }
+
+    auto message_id = find_message_by_date(d->messages, date);
+    if (message_id.is_valid()) {
+      get_dialog_message_by_date_results_[random_id] = {d->dialog_id, message_id};
+    }
+    promise.set_value(Unit());
+    return;
+  }
+  if (d->dialog_id.get_type() == DialogType::SecretChat) {
+    // there is no way to send request to the server
+    return promise.set_value(Unit());
+  }
+
+  td_->create_handler<GetDialogMessageByDateQuery>(std::move(promise))->send(d->dialog_id, date, random_id);
+}
+
+void MessagesManager::on_get_dialog_message_by_date_success(DialogId dialog_id, int32 date, int64 random_id,
+                                                            vector<tl_object_ptr<telegram_api::Message>> &&messages) {
+  auto it = get_dialog_message_by_date_results_.find(random_id);
+  CHECK(it != get_dialog_message_by_date_results_.end());
+  auto &result = it->second;
+  CHECK(result == FullMessageId());
+
+  for (auto &message : messages) {
+    auto message_date = get_message_date(message);
+    auto message_dialog_id = get_message_dialog_id(message);
+    if (message_dialog_id != dialog_id) {
+      LOG(ERROR) << "Receive message in wrong " << message_dialog_id << " instead of " << dialog_id;
+      continue;
+    }
+    if (message_date != 0 && message_date <= date) {
+      result = on_get_message(std::move(message), false, dialog_id.get_type() == DialogType::Channel, false, false,
+                              "on_get_dialog_message_by_date_success");
+      if (result != FullMessageId()) {
+        const Dialog *d = get_dialog(dialog_id);
+        CHECK(d != nullptr);
+        auto message_id = find_message_by_date(d->messages, date);
+        if (!message_id.is_valid()) {
+          LOG(ERROR) << "Failed to find " << result.get_message_id() << " in " << dialog_id << " by date " << date;
+          message_id = result.get_message_id();
+        }
+        get_dialog_message_by_date_results_[random_id] = {dialog_id, message_id};
+        // TODO result must be adjusted by local messages
+        return;
+      }
+    }
+  }
+}
+
+void MessagesManager::on_get_dialog_message_by_date_fail(int64 random_id) {
+  auto erased = get_dialog_message_by_date_results_.erase(random_id);
+  CHECK(erased > 0);
+}
+
+tl_object_ptr<td_api::message> MessagesManager::get_dialog_message_by_date_object(int64 random_id) {
+  auto it = get_dialog_message_by_date_results_.find(random_id);
+  CHECK(it != get_dialog_message_by_date_results_.end());
+  auto full_message_id = std::move(it->second);
+  get_dialog_message_by_date_results_.erase(it);
+  return get_message_object(full_message_id);
+}
+
+void MessagesManager::preload_newer_messages(const Dialog *d, MessageId max_message_id) {
+  if (td_->auth_manager_->is_bot()) {
+    return;
+  }
+
+  MessagesConstIterator p(d, max_message_id);
+  int32 limit = MAX_GET_HISTORY * 3 / 10;
+  while (*p != nullptr && limit-- > 0) {
+    ++p;
+    if (*p) {
+      max_message_id = (*p)->message_id;
+    }
+  }
+  if (limit > 0 && (d->last_message_id == MessageId() || max_message_id.get() < d->last_message_id.get())) {
+    // need to preload some new messages
+    LOG(INFO) << "Preloading newer after " << max_message_id;
+    load_messages(d->dialog_id, max_message_id, -MAX_GET_HISTORY + 1, MAX_GET_HISTORY, 3, false, Promise<Unit>());
+  }
+}
+
+void MessagesManager::preload_older_messages(const Dialog *d, MessageId min_message_id) {
+  if (td_->auth_manager_->is_bot()) {
+    return;
+  }
+
+  /*
+    if (d->first_remote_message_id == -1) {
+      // nothing left to preload from server
+      return;
+    }
+  */
+  MessagesConstIterator p(d, min_message_id);
+  int32 limit = MAX_GET_HISTORY * 3 / 10 + 1;
+  while (*p != nullptr && limit-- > 0) {
+    min_message_id = (*p)->message_id;
+    --p;
+  }
+  if (limit > 0) {
+    // need to preload some old messages
+    LOG(INFO) << "Preloading older before " << min_message_id;
+    load_messages(d->dialog_id, min_message_id, 0, MAX_GET_HISTORY / 2, 3, false, Promise<Unit>());
+  }
+}
+
+void MessagesManager::on_get_history_from_database(DialogId dialog_id, MessageId from_message_id, int32 offset,
+                                                   int32 limit, bool from_the_end, bool only_local,
+                                                   vector<BufferSlice> &&messages, Promise<Unit> &&promise) {
+  CHECK(-limit < offset && offset <= 0);
+  CHECK(offset < 0 || from_the_end);
+
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    LOG(WARNING) << "Ignore result of get_history_from_database in " << dialog_id;
+    promise.set_value(Unit());
+    return;
+  }
+
+  auto d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+
+  LOG(INFO) << "Receive " << messages.size() << " history messages from database "
+            << (from_the_end ? "from the end " : "") << "in " << dialog_id << " from " << from_message_id
+            << " with offset " << offset << " and limit " << limit << ". First database message is "
+            << d->first_database_message_id << ", have_full_history = " << d->have_full_history;
+
+  if (messages.empty() && from_the_end && d->have_full_history) {
+    set_dialog_is_empty(d, "on_get_history_from_database empty");
+  }
+
+  bool have_next = false;
+  bool need_update = false;
+  bool need_update_dialog_pos = false;
+  bool added_new_message = false;
+  MessageId last_added_message_id;
+  Message *next_message = nullptr;
+  Dependencies dependencies;
+  bool is_first = true;
+  for (auto &message_slice : messages) {
+    if (!d->first_database_message_id.is_valid() && !d->have_full_history) {
+      break;
+    }
+    auto message = make_unique<Message>();
+    log_event_parse(*message, message_slice.as_slice()).ensure();
+    if (message->message_id.get() < d->first_database_message_id.get()) {
+      if (d->have_full_history) {
+        LOG(ERROR) << "Have full history in the " << dialog_id << " and receive " << message->message_id
+                   << " from database, but first database message is " << d->first_database_message_id;
+      } else {
+        break;
+      }
+    }
+    if (!have_next &&
+        (from_the_end || (is_first && offset < -1 && message->message_id.get() <= from_message_id.get())) &&
+        message->message_id.get() < d->last_message_id.get()) {
+      // last message in the dialog must be attached to the next local message
+      have_next = true;
+    }
+
+    message->have_previous = false;
+    message->have_next = have_next;
+    message->from_database = true;
+
+    auto old_message = get_message(d, message->message_id);
+    if (old_message == nullptr && message->content->get_id() == MessageText::ID) {
+      auto web_page_id = static_cast<const MessageText *>(message->content.get())->web_page_id;
+      if (web_page_id.is_valid()) {
+        td_->web_pages_manager_->have_web_page_force(web_page_id);
+      }
+    }
+    Message *m = old_message ? old_message
+                             : add_message_to_dialog(d, std::move(message), false, &need_update,
+                                                     &need_update_dialog_pos, "on_get_history_from_database");
+    if (m != nullptr) {
+      if (!have_next) {
+        last_added_message_id = m->message_id;
+      }
+      if (old_message == nullptr) {
+        add_message_dependencies(dependencies, dialog_id, m);
+        added_new_message = true;
+      } else if (m->message_id != from_message_id) {
+        added_new_message = true;
+      }
+      if (next_message != nullptr && !next_message->have_previous) {
+        LOG(INFO) << "Fix have_previous for " << next_message->message_id;
+        next_message->have_previous = true;
+        attach_message_to_previous(d, next_message->message_id);
+      }
+
+      have_next = true;
+      next_message = m;
+    }
+    is_first = false;
+  }
+  resolve_dependencies_force(dependencies);
+
+  if (!added_new_message && !only_local && dialog_id.get_type() != DialogType::SecretChat) {
+    if (from_the_end) {
+      from_message_id = MessageId();
+    }
+    load_messages(dialog_id, from_message_id, offset, limit, 1, false, std::move(promise));
+    return;
+  }
+
+  if (from_the_end && last_added_message_id.is_valid()) {
+    // CHECK(d->first_database_message_id.is_valid());
+    // CHECK(last_added_message_id.get() >= d->first_database_message_id.get());
+    if (last_added_message_id.get() > d->last_message_id.get() && d->last_new_message_id.is_valid()) {
+      set_dialog_last_message_id(d, last_added_message_id, "on_get_history_from_database");
+      need_update_dialog_pos = true;
+    }
+    if (last_added_message_id.get() != d->last_database_message_id.get()) {
+      set_dialog_last_database_message_id(d, last_added_message_id, "on_get_history_from_database");
+      if (last_added_message_id.get() < d->first_database_message_id.get() ||
+          !d->first_database_message_id.is_valid()) {
+        CHECK(next_message != nullptr);
+        CHECK(d->have_full_history);
+        LOG(ERROR) << "Fix first database message id in " << dialog_id << " from " << d->first_database_message_id
+                   << " to " << next_message->message_id;
+        set_dialog_first_database_message_id(d, next_message->message_id, "on_get_history_from_database");
+      }
+      on_dialog_updated(dialog_id, "on_get_history_from_database");
+    }
+  }
+
+  if (need_update_dialog_pos) {
+    send_update_chat_last_message(d, "on_get_history_from_database");
+  }
+
+  promise.set_value(Unit());
+}
+
+void MessagesManager::get_history_from_the_end(DialogId dialog_id, bool from_database, bool only_local,
+                                               Promise<Unit> &&promise) {
+  CHECK(dialog_id.is_valid());
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    // can't get history in dialogs without read access
+    return promise.set_value(Unit());
+  }
+  const int32 limit = MAX_GET_HISTORY;
+  if (from_database && G()->parameters().use_message_db) {
+    LOG(INFO) << "Get history from the end of " << dialog_id << " from database";
+    MessagesDbMessagesQuery db_query;
+    db_query.dialog_id = dialog_id;
+    db_query.from_message_id = MessageId::max();
+    db_query.limit = limit;
+    G()->td_db()->get_messages_db_async()->get_messages(
+        db_query, PromiseCreator::lambda([dialog_id, only_local, limit, actor_id = actor_id(this),
+                                          promise = std::move(promise)](MessagesDbMessagesResult result) mutable {
+          send_closure(actor_id, &MessagesManager::on_get_history_from_database, dialog_id, MessageId::max(), 0, limit,
+                       true, only_local, std::move(result.messages), std::move(promise));
+        }));
+  } else {
+    if (only_local || dialog_id.get_type() == DialogType::SecretChat) {
+      promise.set_value(Unit());
+      return;
+    }
+
+    LOG(INFO) << "Get history from the end of " << dialog_id << " from server";
+    td_->create_handler<GetHistoryQuery>(std::move(promise))->send_get_from_the_end(dialog_id, limit);
+  }
+}
+
+void MessagesManager::get_history(DialogId dialog_id, MessageId from_message_id, int32 offset, int32 limit,
+                                  bool from_database, bool only_local, Promise<Unit> &&promise) {
+  CHECK(dialog_id.is_valid());
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    // can't get history in dialogs without read access
+    return promise.set_value(Unit());
+  }
+  if (from_database && G()->parameters().use_message_db) {
+    LOG(INFO) << "Get history in " << dialog_id << " from " << from_message_id << " with offset " << offset
+              << " and limit " << limit << " from database";
+    MessagesDbMessagesQuery db_query;
+    db_query.dialog_id = dialog_id;
+    db_query.from_message_id = from_message_id;
+    db_query.offset = offset;
+    db_query.limit = limit;
+    G()->td_db()->get_messages_db_async()->get_messages(
+        db_query,
+        PromiseCreator::lambda([dialog_id, from_message_id, offset, limit, only_local, actor_id = actor_id(this),
+                                promise = std::move(promise)](MessagesDbMessagesResult result) mutable {
+          send_closure(actor_id, &MessagesManager::on_get_history_from_database, dialog_id, from_message_id, offset,
+                       limit, false, only_local, std::move(result.messages), std::move(promise));
+        }));
+  } else {
+    if (only_local || dialog_id.get_type() == DialogType::SecretChat) {
+      return promise.set_value(Unit());
+    }
+
+    LOG(INFO) << "Get history in " << dialog_id << " from " << from_message_id << " with offset " << offset
+              << " and limit " << limit << " from server";
+    td_->create_handler<GetHistoryQuery>(std::move(promise))
+        ->send(dialog_id, from_message_id.get_next_server_message_id(), offset, limit);
+  }
+}
+
+void MessagesManager::load_messages(DialogId dialog_id, MessageId from_message_id, int32 offset, int32 limit,
+                                    int left_tries, bool only_local, Promise<Unit> &&promise) {
+  LOG(INFO) << "Load " << (only_local ? "local " : "") << "messages in " << dialog_id << " from " << from_message_id
+            << " with offset = " << offset << " and limit = " << limit << ". " << left_tries << " tries left";
+  CHECK(offset <= 0);
+  CHECK(left_tries > 0);
+  only_local |= dialog_id.get_type() == DialogType::SecretChat;
+  if (!only_local) {
+    Dialog *d = get_dialog(dialog_id);
+    if (d != nullptr && d->have_full_history) {
+      LOG(INFO) << "Have full history in " << dialog_id << ", so don't need to get chat history from server";
+      only_local = true;
+    }
+  }
+  bool from_database = (left_tries > 2 || only_local) && G()->parameters().use_message_db;
+  // TODO do not send requests to database if (from_message_id < d->first_database_message_id ||
+  // !d->first_database_message_id.is_valid()) && !d->have_full_history
+
+  if (from_message_id == MessageId()) {
+    get_history_from_the_end(dialog_id, from_database, only_local, std::move(promise));
+    return;
+  }
+  if (offset >= -1) {
+    // get history before some server or local message
+    limit = min(max(limit + offset + 1, MAX_GET_HISTORY / 2), MAX_GET_HISTORY);
+    offset = -1;
+  } else {
+    // get history around some server or local message
+    int32 messages_to_load = max(MAX_GET_HISTORY, limit);
+    int32 max_add = messages_to_load - limit;
+    offset -= max_add;
+    limit = MAX_GET_HISTORY;
+  }
+  get_history(dialog_id, from_message_id, offset, limit, from_database, only_local, std::move(promise));
+}
+
+tl_object_ptr<td_api::message> MessagesManager::get_message_object(FullMessageId full_message_id) {
+  auto dialog_id = full_message_id.get_dialog_id();
+  Dialog *d = get_dialog(dialog_id);
+  return get_message_object(dialog_id, get_message_force(d, full_message_id.get_message_id()));
+}
+
+tl_object_ptr<td_api::message> MessagesManager::get_message_object(DialogId dialog_id, const Message *message) const {
+  if (message == nullptr) {
+    return nullptr;
+  }
+
+  // TODO get_message_sending_state_object
+  tl_object_ptr<td_api::MessageSendingState> sending_state;
+  if (message->is_failed_to_send) {
+    sending_state = make_tl_object<td_api::messageSendingStateFailed>();
+  } else if (message->message_id.is_yet_unsent()) {
+    sending_state = make_tl_object<td_api::messageSendingStatePending>();
+  }
+
+  bool can_delete = true;
+  auto dialog_type = dialog_id.get_type();
+  if (dialog_type == DialogType::Channel) {
+    auto dialog_status = td_->contacts_manager_->get_channel_status(dialog_id.get_channel_id());
+    can_delete = can_delete_channel_message(dialog_status, message, td_->auth_manager_->is_bot());
+  }
+
+  DialogId my_dialog_id(td_->contacts_manager_->get_my_id("get_message_object"));
+  bool can_delete_for_self = false;
+  bool can_delete_for_all_users = can_delete && can_revoke_message(dialog_id, message);
+  if (can_delete) {
+    switch (dialog_type) {
+      case DialogType::User:
+      case DialogType::Chat:
+        // TODO allow to delete yet unsent message just for self
+        can_delete_for_self = !message->message_id.is_yet_unsent() || dialog_id == my_dialog_id;
+        break;
+      case DialogType::Channel:
+      case DialogType::SecretChat:
+        can_delete_for_self = !can_delete_for_all_users;
+        break;
+      case DialogType::None:
+      default:
+        UNREACHABLE();
+    }
+  }
+
+  bool is_outgoing = message->is_outgoing || sending_state != nullptr;
+  if (dialog_id == my_dialog_id) {
+    // in Saved Messages all messages without forward_info->from_dialog_id should be outgoing
+    if (message->forward_info == nullptr || !message->forward_info->from_dialog_id.is_valid()) {
+      is_outgoing = true;
+    }
+  }
+  return make_tl_object<td_api::message>(
+      message->message_id.get(), td_->contacts_manager_->get_user_id_object(message->sender_user_id, "sender_user_id"),
+      dialog_id.get(), std::move(sending_state), is_outgoing, can_edit_message(dialog_id, message, false, true),
+      can_forward_message(dialog_id, message), can_delete_for_self, can_delete_for_all_users, message->is_channel_post,
+      message->contains_unread_mention, message->date, message->edit_date,
+      get_message_forward_info_object(message->forward_info), message->reply_to_message_id.get(), message->ttl,
+      message->ttl_expires_at != 0 ? max(message->ttl_expires_at - Time::now(), 1e-3) : message->ttl,
+      td_->contacts_manager_->get_user_id_object(message->via_bot_user_id, "via_bot_user_id"),
+      message->author_signature, message->views, message->media_album_id,
+      get_message_content_object(message->content.get(), message->date, message->is_content_secret),
+      get_reply_markup_object(message->reply_markup));
+}
+
+tl_object_ptr<td_api::messages> MessagesManager::get_messages_object(int32 total_count, DialogId dialog_id,
+                                                                     const vector<MessageId> &message_ids) {
+  Dialog *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+  return get_messages_object(total_count, transform(message_ids, [this, dialog_id, d](MessageId message_id) {
+                               return get_message_object(dialog_id, get_message_force(d, message_id));
+                             }));
+}
+
+tl_object_ptr<td_api::messages> MessagesManager::get_messages_object(int32 total_count,
+                                                                     const vector<FullMessageId> &full_message_ids) {
+  return get_messages_object(total_count, transform(full_message_ids, [this](FullMessageId full_message_id) {
+                               return get_message_object(full_message_id);
+                             }));
+}
+
+tl_object_ptr<td_api::messages> MessagesManager::get_messages_object(
+    int32 total_count, vector<tl_object_ptr<td_api::message>> &&messages) {
+  if (total_count == -1) {
+    total_count = narrow_cast<int32>(messages.size());
+  }
+  return td_api::make_object<td_api::messages>(total_count, std::move(messages));
+}
+
+bool MessagesManager::need_skip_bot_commands(DialogId dialog_id, bool is_bot) const {
+  if (is_bot) {
+    return false;
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      return !td_->contacts_manager_->is_user_bot(dialog_id.get_user_id());
+    case DialogType::SecretChat: {
+      auto user_id = td_->contacts_manager_->get_secret_chat_user_id(dialog_id.get_secret_chat_id());
+      return !td_->contacts_manager_->is_user_bot(user_id);
+    }
+    case DialogType::Chat:
+    case DialogType::Channel:
+    case DialogType::None:
+      return false;
+    default:
+      UNREACHABLE();
+      return false;
+  }
+}
+
+Result<FormattedText> MessagesManager::process_input_caption(DialogId dialog_id,
+                                                             tl_object_ptr<td_api::formattedText> &&text,
+                                                             bool is_bot) const {
+  if (text == nullptr) {
+    return FormattedText();
+  }
+  TRY_RESULT(entities, get_message_entities(td_->contacts_manager_.get(), std::move(text->entities_)));
+  TRY_STATUS(fix_formatted_text(text->text_, entities, true, false, need_skip_bot_commands(dialog_id, is_bot), false));
+  return FormattedText{std::move(text->text_), std::move(entities)};
+}
+
+Result<InputMessageText> MessagesManager::process_input_message_text(
+    DialogId dialog_id, tl_object_ptr<td_api::InputMessageContent> &&input_message_content, bool is_bot,
+    bool for_draft) const {
+  CHECK(input_message_content != nullptr);
+  CHECK(input_message_content->get_id() == td_api::inputMessageText::ID);
+  auto input_message_text = static_cast<td_api::inputMessageText *>(input_message_content.get());
+  if (input_message_text->text_ == nullptr) {
+    if (for_draft) {
+      return InputMessageText{FormattedText(), input_message_text->disable_web_page_preview_,
+                              input_message_text->clear_draft_};
+    }
+
+    return Status::Error(400, "Message text can't be empty");
+  }
+
+  TRY_RESULT(entities,
+             get_message_entities(td_->contacts_manager_.get(), std::move(input_message_text->text_->entities_)));
+  TRY_STATUS(fix_formatted_text(input_message_text->text_->text_, entities, for_draft, false,
+                                need_skip_bot_commands(dialog_id, is_bot), for_draft));
+  return InputMessageText{FormattedText{std::move(input_message_text->text_->text_), std::move(entities)},
+                          input_message_text->disable_web_page_preview_, input_message_text->clear_draft_};
+}
+
+Result<std::pair<Location, int32>> MessagesManager::process_input_message_location(
+    tl_object_ptr<td_api::InputMessageContent> &&input_message_content) {
+  CHECK(input_message_content != nullptr);
+  CHECK(input_message_content->get_id() == td_api::inputMessageLocation::ID);
+  auto input_location = static_cast<const td_api::inputMessageLocation *>(input_message_content.get());
+
+  Location location(input_location->location_);
+  if (location.empty()) {
+    return Status::Error(400, "Wrong location specified");
+  }
+
+  auto period = input_location->live_period_;
+  if (period != 0 && (period < MIN_LIVE_LOCATION_PERIOD || period > MAX_LIVE_LOCATION_PERIOD)) {
+    return Status::Error(400, "Wrong live location period specified");
+  }
+
+  return std::make_pair(std::move(location), period);
+}
+
+Result<Venue> MessagesManager::process_input_message_venue(
+    tl_object_ptr<td_api::InputMessageContent> &&input_message_content) {
+  CHECK(input_message_content != nullptr);
+  CHECK(input_message_content->get_id() == td_api::inputMessageVenue::ID);
+  auto venue = std::move(static_cast<td_api::inputMessageVenue *>(input_message_content.get())->venue_);
+
+  if (venue == nullptr) {
+    return Status::Error(400, "Venue can't be empty");
+  }
+
+  if (!clean_input_string(venue->title_)) {
+    return Status::Error(400, "Venue title must be encoded in UTF-8");
+  }
+  if (!clean_input_string(venue->address_)) {
+    return Status::Error(400, "Venue address must be encoded in UTF-8");
+  }
+  if (!clean_input_string(venue->provider_)) {
+    return Status::Error(400, "Venue provider must be encoded in UTF-8");
+  }
+  if (!clean_input_string(venue->id_)) {
+    return Status::Error(400, "Venue identifier must be encoded in UTF-8");
+  }
+
+  Venue result(venue);
+  if (result.empty()) {
+    return Status::Error(400, "Wrong venue location specified");
+  }
+
+  return result;
+}
+
+Result<Contact> MessagesManager::process_input_message_contact(
+    tl_object_ptr<td_api::InputMessageContent> &&input_message_content) {
+  CHECK(input_message_content != nullptr);
+  CHECK(input_message_content->get_id() == td_api::inputMessageContact::ID);
+  auto contact = std::move(static_cast<td_api::inputMessageContact *>(input_message_content.get())->contact_);
+
+  if (!clean_input_string(contact->phone_number_)) {
+    return Status::Error(400, "Phone number must be encoded in UTF-8");
+  }
+  if (!clean_input_string(contact->first_name_)) {
+    return Status::Error(400, "First name must be encoded in UTF-8");
+  }
+  if (!clean_input_string(contact->last_name_)) {
+    return Status::Error(400, "Last name must be encoded in UTF-8");
+  }
+
+  return Contact(contact->phone_number_, contact->first_name_, contact->last_name_, contact->user_id_);
+}
+
+Result<Game> MessagesManager::process_input_message_game(
+    tl_object_ptr<td_api::InputMessageContent> &&input_message_content) const {
+  CHECK(input_message_content != nullptr);
+  CHECK(input_message_content->get_id() == td_api::inputMessageGame::ID);
+  auto input_message_game = move_tl_object_as<td_api::inputMessageGame>(input_message_content);
+
+  UserId bot_user_id(input_message_game->bot_user_id_);
+  if (!td_->contacts_manager_->have_input_user(bot_user_id)) {
+    return Status::Error(400, "Game owner bot is not accessible");
+  }
+
+  if (!clean_input_string(input_message_game->game_short_name_)) {
+    return Status::Error(400, "Game short name must be encoded in UTF-8");
+  }
+
+  // TODO validate game_short_name
+  if (input_message_game->game_short_name_.empty()) {
+    return Status::Error(400, "Game short name must be non-empty");
+  }
+
+  return Game(bot_user_id, std::move(input_message_game->game_short_name_));
+}
+
+SecretInputMedia MessagesManager::get_secret_input_media(const MessageContent *content,
+                                                         tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                                         BufferSlice thumbnail, int32 layer) {
+  switch (content->get_id()) {
+    case MessageAnimation::ID: {
+      auto m = static_cast<const MessageAnimation *>(content);
+      return td_->animations_manager_->get_secret_input_media(m->file_id, std::move(input_file), m->caption.text,
+                                                              std::move(thumbnail));
+    }
+    case MessageAudio::ID: {
+      auto m = static_cast<const MessageAudio *>(content);
+      return td_->audios_manager_->get_secret_input_media(m->file_id, std::move(input_file), m->caption.text,
+                                                          std::move(thumbnail));
+    }
+    case MessageContact::ID: {
+      auto m = static_cast<const MessageContact *>(content);
+      return m->contact.get_secret_input_media_contact();
+    }
+    case MessageDocument::ID: {
+      auto m = static_cast<const MessageDocument *>(content);
+      return td_->documents_manager_->get_secret_input_media(m->file_id, std::move(input_file), m->caption.text,
+                                                             std::move(thumbnail));
+    }
+    case MessageLocation::ID: {
+      auto m = static_cast<const MessageLocation *>(content);
+      return m->location.get_secret_input_media_geo_point();
+    }
+    case MessagePhoto::ID: {
+      auto m = static_cast<const MessagePhoto *>(content);
+      return photo_get_secret_input_media(td_->file_manager_.get(), m->photo, std::move(input_file), m->caption.text,
+                                          std::move(thumbnail));
+    }
+    case MessageSticker::ID: {
+      auto m = static_cast<const MessageSticker *>(content);
+      return td_->stickers_manager_->get_secret_input_media(m->file_id, std::move(input_file), std::move(thumbnail));
+    }
+    case MessageText::ID: {
+      CHECK(input_file == nullptr);
+      CHECK(thumbnail.empty());
+      auto m = static_cast<const MessageText *>(content);
+      return td_->web_pages_manager_->get_secret_input_media(m->web_page_id);
+    }
+    case MessageVenue::ID: {
+      auto m = static_cast<const MessageVenue *>(content);
+      return m->venue.get_secret_input_media_venue();
+    }
+    case MessageVideo::ID: {
+      auto m = static_cast<const MessageVideo *>(content);
+      return td_->videos_manager_->get_secret_input_media(m->file_id, std::move(input_file), m->caption.text,
+                                                          std::move(thumbnail));
+    }
+    case MessageVideoNote::ID: {
+      auto m = static_cast<const MessageVideoNote *>(content);
+      return td_->video_notes_manager_->get_secret_input_media(m->file_id, std::move(input_file), std::move(thumbnail),
+                                                               layer);
+    }
+    case MessageVoiceNote::ID: {
+      auto m = static_cast<const MessageVoiceNote *>(content);
+      return td_->voice_notes_manager_->get_secret_input_media(m->file_id, std::move(input_file), m->caption.text);
+    }
+    case MessageLiveLocation::ID:
+    case MessageGame::ID:
+    case MessageInvoice::ID:
+    case MessageUnsupported::ID:
+    case MessageChatCreate::ID:
+    case MessageChatChangeTitle::ID:
+    case MessageChatChangePhoto::ID:
+    case MessageChatDeletePhoto::ID:
+    case MessageChatDeleteHistory::ID:
+    case MessageChatAddUsers::ID:
+    case MessageChatJoinedByLink::ID:
+    case MessageChatDeleteUser::ID:
+    case MessageChatMigrateTo::ID:
+    case MessageChannelCreate::ID:
+    case MessageChannelMigrateFrom::ID:
+    case MessagePinMessage::ID:
+    case MessageGameScore::ID:
+    case MessageScreenshotTaken::ID:
+    case MessageChatSetTtl::ID:
+    case MessagePaymentSuccessful::ID:
+    case MessageContactRegistered::ID:
+    case MessageExpiredPhoto::ID:
+    case MessageExpiredVideo::ID:
+    case MessageCustomServiceAction::ID:
+    case MessageWebsiteConnected::ID:
+      break;
+    default:
+      UNREACHABLE();
+  }
+  return SecretInputMedia{};
+}
+
+tl_object_ptr<telegram_api::invoice> MessagesManager::get_input_invoice(const Invoice &invoice) const {
+  int32 flags = 0;
+  if (invoice.is_test) {
+    flags |= telegram_api::invoice::TEST_MASK;
+  }
+  if (invoice.need_name) {
+    flags |= telegram_api::invoice::NAME_REQUESTED_MASK;
+  }
+  if (invoice.need_phone_number) {
+    flags |= telegram_api::invoice::PHONE_REQUESTED_MASK;
+  }
+  if (invoice.need_email_address) {
+    flags |= telegram_api::invoice::EMAIL_REQUESTED_MASK;
+  }
+  if (invoice.need_shipping_address) {
+    flags |= telegram_api::invoice::SHIPPING_ADDRESS_REQUESTED_MASK;
+  }
+  if (invoice.send_phone_number_to_provider) {
+    flags |= telegram_api::invoice::PHONE_TO_PROVIDER_MASK;
+  }
+  if (invoice.send_email_address_to_provider) {
+    flags |= telegram_api::invoice::EMAIL_TO_PROVIDER_MASK;
+  }
+  if (invoice.is_flexible) {
+    flags |= telegram_api::invoice::FLEXIBLE_MASK;
+  }
+
+  vector<tl_object_ptr<telegram_api::labeledPrice>> prices;
+  prices.reserve(invoice.price_parts.size());
+  for (auto &price : invoice.price_parts) {
+    prices.push_back(make_tl_object<telegram_api::labeledPrice>(price.label, price.amount));
+  }
+
+  return make_tl_object<telegram_api::invoice>(
+      flags, false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/,
+      false /*ignored*/, false /*ignored*/, false /*ignored*/, invoice.currency, std::move(prices));
+}
+
+tl_object_ptr<telegram_api::inputWebDocument> MessagesManager::get_input_web_document(const Photo &photo) const {
+  if (photo.id == -2) {
+    return nullptr;
+  }
+
+  CHECK(photo.photos.size() == 1);
+  const PhotoSize &size = photo.photos[0];
+  CHECK(size.file_id.is_valid());
+
+  vector<tl_object_ptr<telegram_api::DocumentAttribute>> attributes;
+  if (size.dimensions.width != 0 && size.dimensions.height != 0) {
+    attributes.push_back(
+        make_tl_object<telegram_api::documentAttributeImageSize>(size.dimensions.width, size.dimensions.height));
+  }
+
+  auto file_view = td_->file_manager_->get_file_view(size.file_id);
+  CHECK(file_view.has_url());
+
+  auto file_name = get_url_file_name(file_view.url());
+  return make_tl_object<telegram_api::inputWebDocument>(
+      file_view.url(), size.size, MimeType::from_extension(PathView(file_name).extension(), "image/jpeg"),
+      std::move(attributes));
+}
+
+tl_object_ptr<telegram_api::inputMediaInvoice> MessagesManager::get_input_media_invoice(
+    const MessageInvoice *message_invoice) const {
+  CHECK(message_invoice != nullptr);
+  int32 flags = 0;
+  auto input_web_document = get_input_web_document(message_invoice->photo);
+  if (input_web_document != nullptr) {
+    flags |= telegram_api::inputMediaInvoice::PHOTO_MASK;
+  }
+
+  return make_tl_object<telegram_api::inputMediaInvoice>(
+      flags, message_invoice->title, message_invoice->description, std::move(input_web_document),
+      get_input_invoice(message_invoice->invoice), BufferSlice(message_invoice->payload),
+      message_invoice->provider_token,
+      telegram_api::make_object<telegram_api::dataJSON>(
+          message_invoice->provider_data.empty() ? "null" : message_invoice->provider_data),
+      message_invoice->start_parameter);
+}
+
+tl_object_ptr<telegram_api::InputMedia> MessagesManager::get_input_media(
+    const MessageContent *content, tl_object_ptr<telegram_api::InputFile> input_file,
+    tl_object_ptr<telegram_api::InputFile> input_thumbnail, int32 ttl) {
+  switch (content->get_id()) {
+    case MessageAnimation::ID: {
+      auto m = static_cast<const MessageAnimation *>(content);
+      return td_->animations_manager_->get_input_media(m->file_id, std::move(input_file), std::move(input_thumbnail));
+    }
+    case MessageAudio::ID: {
+      auto m = static_cast<const MessageAudio *>(content);
+      return td_->audios_manager_->get_input_media(m->file_id, std::move(input_file), std::move(input_thumbnail));
+    }
+    case MessageContact::ID: {
+      auto m = static_cast<const MessageContact *>(content);
+      return m->contact.get_input_media_contact();
+    }
+    case MessageDocument::ID: {
+      auto m = static_cast<const MessageDocument *>(content);
+      return td_->documents_manager_->get_input_media(m->file_id, std::move(input_file), std::move(input_thumbnail));
+    }
+    case MessageGame::ID: {
+      auto m = static_cast<const MessageGame *>(content);
+      return m->game.get_input_media_game(td_);
+    }
+    case MessageInvoice::ID: {
+      auto m = static_cast<const MessageInvoice *>(content);
+      return get_input_media_invoice(m);
+    }
+    case MessageLiveLocation::ID: {
+      auto m = static_cast<const MessageLiveLocation *>(content);
+      return make_tl_object<telegram_api::inputMediaGeoLive>(m->location.get_input_geo_point(), m->period);
+    }
+    case MessageLocation::ID: {
+      auto m = static_cast<const MessageLocation *>(content);
+      return m->location.get_input_media_geo_point();
+    }
+    case MessagePhoto::ID: {
+      auto m = static_cast<const MessagePhoto *>(content);
+      return photo_get_input_media(td_->file_manager_.get(), m->photo, std::move(input_file), ttl);
+    }
+    case MessageSticker::ID: {
+      auto m = static_cast<const MessageSticker *>(content);
+      return td_->stickers_manager_->get_input_media(m->file_id, std::move(input_file), std::move(input_thumbnail));
+    }
+    case MessageVenue::ID: {
+      auto m = static_cast<const MessageVenue *>(content);
+      return m->venue.get_input_media_venue();
+    }
+    case MessageVideo::ID: {
+      auto m = static_cast<const MessageVideo *>(content);
+      return td_->videos_manager_->get_input_media(m->file_id, std::move(input_file), std::move(input_thumbnail), ttl);
+    }
+    case MessageVideoNote::ID: {
+      auto m = static_cast<const MessageVideoNote *>(content);
+      return td_->video_notes_manager_->get_input_media(m->file_id, std::move(input_file), std::move(input_thumbnail));
+    }
+    case MessageVoiceNote::ID: {
+      auto m = static_cast<const MessageVoiceNote *>(content);
+      return td_->voice_notes_manager_->get_input_media(m->file_id, std::move(input_file));
+    }
+    case MessageText::ID:
+    case MessageUnsupported::ID:
+    case MessageChatCreate::ID:
+    case MessageChatChangeTitle::ID:
+    case MessageChatChangePhoto::ID:
+    case MessageChatDeletePhoto::ID:
+    case MessageChatDeleteHistory::ID:
+    case MessageChatAddUsers::ID:
+    case MessageChatJoinedByLink::ID:
+    case MessageChatDeleteUser::ID:
+    case MessageChatMigrateTo::ID:
+    case MessageChannelCreate::ID:
+    case MessageChannelMigrateFrom::ID:
+    case MessagePinMessage::ID:
+    case MessageGameScore::ID:
+    case MessageScreenshotTaken::ID:
+    case MessageChatSetTtl::ID:
+    case MessageCall::ID:
+    case MessagePaymentSuccessful::ID:
+    case MessageContactRegistered::ID:
+    case MessageExpiredPhoto::ID:
+    case MessageExpiredVideo::ID:
+    case MessageCustomServiceAction::ID:
+    case MessageWebsiteConnected::ID:
+      break;
+    default:
+      UNREACHABLE();
+  }
+  return nullptr;
+}
+
+void MessagesManager::delete_message_content_thumbnail(MessageContent *content) {
+  switch (content->get_id()) {
+    case MessageAnimation::ID: {
+      auto m = static_cast<MessageAnimation *>(content);
+      return td_->animations_manager_->delete_animation_thumbnail(m->file_id);
+    }
+    case MessageAudio::ID: {
+      auto m = static_cast<MessageAudio *>(content);
+      return td_->audios_manager_->delete_audio_thumbnail(m->file_id);
+    }
+    case MessageDocument::ID: {
+      auto m = static_cast<MessageDocument *>(content);
+      return td_->documents_manager_->delete_document_thumbnail(m->file_id);
+    }
+    case MessagePhoto::ID: {
+      auto m = static_cast<MessagePhoto *>(content);
+      return photo_delete_thumbnail(m->photo);
+    }
+    case MessageSticker::ID: {
+      auto m = static_cast<MessageSticker *>(content);
+      return td_->stickers_manager_->delete_sticker_thumbnail(m->file_id);
+    }
+    case MessageVideo::ID: {
+      auto m = static_cast<MessageVideo *>(content);
+      return td_->videos_manager_->delete_video_thumbnail(m->file_id);
+    }
+    case MessageVideoNote::ID: {
+      auto m = static_cast<MessageVideoNote *>(content);
+      return td_->video_notes_manager_->delete_video_note_thumbnail(m->file_id);
+    }
+    case MessageContact::ID:
+    case MessageGame::ID:
+    case MessageInvoice::ID:
+    case MessageLiveLocation::ID:
+    case MessageLocation::ID:
+    case MessageVenue::ID:
+    case MessageVoiceNote::ID:
+    case MessageText::ID:
+    case MessageUnsupported::ID:
+    case MessageChatCreate::ID:
+    case MessageChatChangeTitle::ID:
+    case MessageChatChangePhoto::ID:
+    case MessageChatDeletePhoto::ID:
+    case MessageChatDeleteHistory::ID:
+    case MessageChatAddUsers::ID:
+    case MessageChatJoinedByLink::ID:
+    case MessageChatDeleteUser::ID:
+    case MessageChatMigrateTo::ID:
+    case MessageChannelCreate::ID:
+    case MessageChannelMigrateFrom::ID:
+    case MessagePinMessage::ID:
+    case MessageGameScore::ID:
+    case MessageScreenshotTaken::ID:
+    case MessageChatSetTtl::ID:
+    case MessageCall::ID:
+    case MessagePaymentSuccessful::ID:
+    case MessageContactRegistered::ID:
+    case MessageExpiredPhoto::ID:
+    case MessageExpiredVideo::ID:
+    case MessageCustomServiceAction::ID:
+    case MessageWebsiteConnected::ID:
+      break;
+    default:
+      UNREACHABLE();
+  }
+}
+
+MessagesManager::Message *MessagesManager::get_message_to_send(Dialog *d, MessageId reply_to_message_id,
+                                                               bool disable_notification, bool from_background,
+                                                               unique_ptr<MessageContent> &&content,
+                                                               bool *need_update_dialog_pos,
+                                                               unique_ptr<MessageForwardInfo> forward_info) {
+  CHECK(d != nullptr);
+  MessageId message_id = get_next_yet_unsent_message_id(d);
+  DialogId dialog_id = d->dialog_id;
+  LOG(INFO) << "Create " << message_id << " in " << dialog_id;
+
+  auto dialog_type = dialog_id.get_type();
+  auto my_id = td_->contacts_manager_->get_my_id("get_message_to_send");
+
+  auto m = make_unique<Message>();
+  m->random_y = get_random_y(message_id);
+  m->message_id = message_id;
+  bool is_channel_post = is_broadcast_channel(dialog_id);
+  if (is_channel_post) {
+    // sender of the post can be hidden
+    if (td_->contacts_manager_->get_channel_sign_messages(dialog_id.get_channel_id())) {
+      m->author_signature = td_->contacts_manager_->get_user_title(my_id);
+    }
+  } else {
+    m->sender_user_id = my_id;
+  }
+  m->date = G()->unix_time();
+  m->reply_to_message_id = reply_to_message_id;
+  m->is_channel_post = is_channel_post;
+  m->is_outgoing = dialog_id != DialogId(my_id);
+  m->from_background = from_background;
+  m->views = is_channel_post ? 1 : 0;
+  m->content = std::move(content);
+  m->forward_info = std::move(forward_info);
+
+  if (td_->auth_manager_->is_bot()) {
+    m->disable_notification = disable_notification;
+  } else {
+    auto notification_settings = get_notification_settings(NotificationSettingsScope(dialog_id.get()), true);
+    CHECK(notification_settings != nullptr);
+    m->disable_notification = notification_settings->silent_send_message;
+  }
+
+  if (dialog_type == DialogType::SecretChat) {
+    m->ttl = td_->contacts_manager_->get_secret_chat_ttl(dialog_id.get_secret_chat_id());
+    if (is_service_message_content(m->content->get_id())) {
+      m->ttl = 0;
+    }
+    m->is_content_secret = is_secret_message_content(m->ttl, m->content->get_id());
+    if (reply_to_message_id.is_valid()) {
+      auto *reply_to_message = get_message_force(d, reply_to_message_id);
+      if (reply_to_message != nullptr) {
+        m->reply_to_random_id = reply_to_message->random_id;
+      } else {
+        m->reply_to_message_id = MessageId();
+      }
+    }
+  }
+
+  m->have_previous = true;
+  m->have_next = true;
+
+  do {
+    m->random_id = Random::secure_int64();
+  } while (m->random_id == 0 || message_random_ids_.find(m->random_id) != message_random_ids_.end());
+  message_random_ids_.insert(m->random_id);
+
+  bool need_update = false;
+  CHECK(have_input_peer(dialog_id, AccessRights::Read));
+  auto result = add_message_to_dialog(d, std::move(m), false, &need_update, need_update_dialog_pos, "send message");
+  CHECK(result != nullptr);
+  return result;
+}
+
+int64 MessagesManager::begin_send_message(DialogId dialog_id, const Message *m) {
+  LOG(INFO) << "Begin to send " << FullMessageId(dialog_id, m->message_id) << " with random_id = " << m->random_id;
+  CHECK(m->random_id != 0 && being_sent_messages_.find(m->random_id) == being_sent_messages_.end());
+  being_sent_messages_[m->random_id] = FullMessageId(dialog_id, m->message_id);
+  debug_being_sent_messages_[m->random_id] = dialog_id;
+  return m->random_id;
+}
+
+Status MessagesManager::can_send_message(DialogId dialog_id) const {
+  if (!have_input_peer(dialog_id, AccessRights::Write)) {
+    return Status::Error(400, "Have no write access to the chat");
+  }
+
+  if (dialog_id.get_type() == DialogType::Channel) {
+    auto channel_id = dialog_id.get_channel_id();
+    auto channel_type = td_->contacts_manager_->get_channel_type(channel_id);
+    auto channel_status = td_->contacts_manager_->get_channel_status(channel_id);
+
+    switch (channel_type) {
+      case ChannelType::Unknown:
+      case ChannelType::Megagroup:
+        if (!channel_status.can_send_messages()) {
+          return Status::Error(400, "Have no rights to send a message");
+        }
+        break;
+      case ChannelType::Broadcast: {
+        if (!channel_status.can_post_messages()) {
+          return Status::Error(400, "Need administrator rights in the channel chat");
+        }
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+  }
+  return Status::OK();
+}
+
+Status MessagesManager::can_send_message_content(DialogId dialog_id, const MessageContent *content,
+                                                 bool is_forward) const {
+  auto dialog_type = dialog_id.get_type();
+  int32 secret_chat_layer = std::numeric_limits<int32>::max();
+  if (dialog_type == DialogType::SecretChat) {
+    auto secret_chat_id = dialog_id.get_secret_chat_id();
+    secret_chat_layer = td_->contacts_manager_->get_secret_chat_layer(secret_chat_id);
+  }
+
+  bool can_send_messages = true;
+  bool can_send_media = true;
+  bool can_send_stickers = true;
+  bool can_send_animations = true;
+  bool can_send_games = true;
+
+  switch (dialog_type) {
+    case DialogType::User:
+    case DialogType::Chat:
+      // ok
+      break;
+    case DialogType::Channel: {
+      auto channel_status = td_->contacts_manager_->get_channel_status(dialog_id.get_channel_id());
+      can_send_messages = channel_status.can_send_messages();
+      can_send_media = channel_status.can_send_media();
+      can_send_stickers = channel_status.can_send_stickers();
+      can_send_animations = channel_status.can_send_animations();
+      can_send_games = channel_status.can_send_games();
+      break;
+    }
+    case DialogType::SecretChat:
+      can_send_games = false;
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+
+  switch (content->get_id()) {
+    case MessageAnimation::ID:
+      if (!can_send_animations) {
+        return Status::Error(400, "Not enough rights to send animations to the chat");
+      }
+      break;
+    case MessageAudio::ID:
+      if (!can_send_media) {
+        return Status::Error(400, "Not enough rights to send audios to the chat");
+      }
+      break;
+    case MessageContact::ID:
+      if (!can_send_messages) {
+        return Status::Error(400, "Not enough rights to send contacts to the chat");
+      }
+      break;
+    case MessageDocument::ID:
+      if (!can_send_media) {
+        return Status::Error(400, "Not enough rights to send documents to the chat");
+      }
+      break;
+    case MessageGame::ID:
+      switch (dialog_id.get_type()) {
+        case DialogType::User:
+        case DialogType::Chat:
+          // ok
+          break;
+        case DialogType::Channel: {
+          auto channel_type = td_->contacts_manager_->get_channel_type(dialog_id.get_channel_id());
+          if (channel_type == ChannelType::Broadcast) {
+            return Status::Error(400, "Games can't be sent to channel chats");
+          }
+          break;
+        }
+        case DialogType::SecretChat:
+          return Status::Error(400, "Games can't be sent to secret chats");
+        case DialogType::None:
+        default:
+          UNREACHABLE();
+      }
+
+      if (!can_send_games) {
+        return Status::Error(400, "Not enough rights to send games to the chat");
+      }
+      break;
+    case MessageInvoice::ID:
+      if (!is_forward) {
+        switch (dialog_type) {
+          case DialogType::User:
+            // ok
+            break;
+          case DialogType::Chat:
+          case DialogType::Channel:
+          case DialogType::SecretChat:
+            return Status::Error(400, "Invoices can be sent only to private chats");
+          case DialogType::None:
+          default:
+            UNREACHABLE();
+        }
+      }
+      break;
+    case MessageLiveLocation::ID:
+      if (!can_send_messages) {
+        return Status::Error(400, "Not enough rights to send live locations to the chat");
+      }
+      break;
+    case MessageLocation::ID:
+      if (!can_send_messages) {
+        return Status::Error(400, "Not enough rights to send locations to the chat");
+      }
+      break;
+    case MessagePhoto::ID:
+      if (!can_send_media) {
+        return Status::Error(400, "Not enough rights to send photos to the chat");
+      }
+      break;
+    case MessageSticker::ID:
+      if (!can_send_stickers) {
+        return Status::Error(400, "Not enough rights to send stickers to the chat");
+      }
+      break;
+    case MessageText::ID:
+      if (!can_send_messages) {
+        return Status::Error(400, "Not enough rights to send text messages to the chat");
+      }
+      break;
+    case MessageVenue::ID:
+      if (!can_send_messages) {
+        return Status::Error(400, "Not enough rights to send venues to the chat");
+      }
+      break;
+    case MessageVideo::ID:
+      if (!can_send_media) {
+        return Status::Error(400, "Not enough rights to send videos to the chat");
+      }
+      break;
+    case MessageVideoNote::ID:
+      if (!can_send_media) {
+        return Status::Error(400, "Not enough rights to send video notes to the chat");
+      }
+      if (secret_chat_layer < SecretChatActor::VOICE_NOTES_LAYER) {
+        return Status::Error(400, PSLICE()
+                                      << "Video notes can't be sent to secret chat with layer " << secret_chat_layer);
+      }
+      break;
+    case MessageVoiceNote::ID:
+      if (!can_send_media) {
+        return Status::Error(400, "Not enough rights to send voice notes to the chat");
+      }
+      break;
+    case MessageChatCreate::ID:
+    case MessageChatChangeTitle::ID:
+    case MessageChatChangePhoto::ID:
+    case MessageChatDeletePhoto::ID:
+    case MessageChatDeleteHistory::ID:
+    case MessageChatAddUsers::ID:
+    case MessageChatJoinedByLink::ID:
+    case MessageChatDeleteUser::ID:
+    case MessageChatMigrateTo::ID:
+    case MessageChannelCreate::ID:
+    case MessageChannelMigrateFrom::ID:
+    case MessagePinMessage::ID:
+    case MessageGameScore::ID:
+    case MessageScreenshotTaken::ID:
+    case MessageChatSetTtl::ID:
+    case MessageUnsupported::ID:
+    case MessageCall::ID:
+    case MessagePaymentSuccessful::ID:
+    case MessageContactRegistered::ID:
+    case MessageExpiredPhoto::ID:
+    case MessageExpiredVideo::ID:
+    case MessageCustomServiceAction::ID:
+    case MessageWebsiteConnected::ID:
+      UNREACHABLE();
+  }
+  return Status::OK();
+}
+
+MessageId MessagesManager::get_persistent_message_id(const Dialog *d, MessageId message_id) const {
+  if (!message_id.is_valid()) {
+    return MessageId();
+  }
+  if (message_id.is_yet_unsent()) {
+    // it is possible that user tries to do something with an already sent message by its temporary id
+    // we need to use real message in this case and transparently replace message_id
+    auto it = d->yet_unsent_message_id_to_persistent_message_id.find(message_id);
+    if (it != d->yet_unsent_message_id_to_persistent_message_id.end()) {
+      return it->second;
+    }
+  }
+
+  return message_id;
+}
+
+MessageId MessagesManager::get_reply_to_message_id(Dialog *d, MessageId message_id) {
+  CHECK(d != nullptr);
+  message_id = get_persistent_message_id(d, message_id);
+  const Message *reply_to_message = get_message_force(d, message_id);
+  if (reply_to_message == nullptr || message_id.is_yet_unsent() ||
+      (message_id.is_local() && d->dialog_id.get_type() != DialogType::SecretChat)) {
+    // TODO local replies to local messages can be allowed
+    // TODO replies to yet unsent messages can be allowed with special handling of them on application restart
+    return MessageId();
+  }
+  return message_id;
+}
+
+FormattedText MessagesManager::get_message_content_caption(const MessageContent *content) {
+  switch (content->get_id()) {
+    case MessageAnimation::ID:
+      return static_cast<const MessageAnimation *>(content)->caption;
+    case MessageAudio::ID:
+      return static_cast<const MessageAudio *>(content)->caption;
+    case MessageDocument::ID:
+      return static_cast<const MessageDocument *>(content)->caption;
+    case MessagePhoto::ID:
+      return static_cast<const MessagePhoto *>(content)->caption;
+    case MessageVideo::ID:
+      return static_cast<const MessageVideo *>(content)->caption;
+    case MessageVoiceNote::ID:
+      return static_cast<const MessageVoiceNote *>(content)->caption;
+    default:
+      return FormattedText();
+  }
+}
+
+int32 MessagesManager::get_message_content_duration(const MessageContent *content) const {
+  CHECK(content != nullptr);
+  switch (content->get_id()) {
+    case MessageAnimation::ID: {
+      auto animation_file_id = static_cast<const MessageAnimation *>(content)->file_id;
+      return td_->animations_manager_->get_animation_duration(animation_file_id);
+    }
+    case MessageAudio::ID: {
+      auto audio_file_id = static_cast<const MessageAudio *>(content)->file_id;
+      return td_->audios_manager_->get_audio_duration(audio_file_id);
+    }
+    case MessageVideo::ID: {
+      auto video_file_id = static_cast<const MessageVideo *>(content)->file_id;
+      return td_->videos_manager_->get_video_duration(video_file_id);
+    }
+    case MessageVideoNote::ID: {
+      auto video_note_file_id = static_cast<const MessageVideoNote *>(content)->file_id;
+      return td_->video_notes_manager_->get_video_note_duration(video_note_file_id);
+    }
+    case MessageVoiceNote::ID: {
+      auto voice_file_id = static_cast<const MessageVoiceNote *>(content)->file_id;
+      return td_->voice_notes_manager_->get_voice_note_duration(voice_file_id);
+    }
+  }
+  return 0;
+}
+
+FileId MessagesManager::get_message_content_file_id(const MessageContent *content) {
+  switch (content->get_id()) {
+    case MessageAnimation::ID:
+      return static_cast<const MessageAnimation *>(content)->file_id;
+    case MessageAudio::ID:
+      return static_cast<const MessageAudio *>(content)->file_id;
+    case MessageDocument::ID:
+      return static_cast<const MessageDocument *>(content)->file_id;
+    case MessagePhoto::ID:
+      for (auto &size : static_cast<const MessagePhoto *>(content)->photo.photos) {
+        if (size.type == 'i') {
+          return size.file_id;
+        }
+      }
+      break;
+    case MessageSticker::ID:
+      return static_cast<const MessageSticker *>(content)->file_id;
+    case MessageVideo::ID:
+      return static_cast<const MessageVideo *>(content)->file_id;
+    case MessageVideoNote::ID:
+      return static_cast<const MessageVideoNote *>(content)->file_id;
+    case MessageVoiceNote::ID:
+      return static_cast<const MessageVoiceNote *>(content)->file_id;
+    default:
+      break;
+  }
+  return FileId();
+}
+
+void MessagesManager::update_message_content_file_id_remote(MessageContent *content, FileId file_id) {
+  if (file_id.get_remote() == 0) {
+    return;
+  }
+  FileId *old_file_id = [&]() {
+    switch (content->get_id()) {
+      case MessageAnimation::ID:
+        return &static_cast<MessageAnimation *>(content)->file_id;
+      case MessageAudio::ID:
+        return &static_cast<MessageAudio *>(content)->file_id;
+      case MessageDocument::ID:
+        return &static_cast<MessageDocument *>(content)->file_id;
+      case MessageSticker::ID:
+        return &static_cast<MessageSticker *>(content)->file_id;
+      case MessageVideo::ID:
+        return &static_cast<MessageVideo *>(content)->file_id;
+      case MessageVideoNote::ID:
+        return &static_cast<MessageVideoNote *>(content)->file_id;
+      case MessageVoiceNote::ID:
+        return &static_cast<MessageVoiceNote *>(content)->file_id;
+      default:
+        return static_cast<FileId *>(nullptr);
+    }
+  }();
+  if (old_file_id != nullptr && *old_file_id == file_id && old_file_id->get_remote() == 0) {
+    *old_file_id = file_id;
+  }
+}
+
+FileId MessagesManager::get_message_content_thumbnail_file_id(const MessageContent *content) const {
+  switch (content->get_id()) {
+    case MessageAnimation::ID:
+      return td_->animations_manager_->get_animation_thumbnail_file_id(
+          static_cast<const MessageAnimation *>(content)->file_id);
+    case MessageAudio::ID:
+      return td_->audios_manager_->get_audio_thumbnail_file_id(static_cast<const MessageAudio *>(content)->file_id);
+    case MessageDocument::ID:
+      return td_->documents_manager_->get_document_thumbnail_file_id(
+          static_cast<const MessageDocument *>(content)->file_id);
+    case MessagePhoto::ID:
+      for (auto &size : static_cast<const MessagePhoto *>(content)->photo.photos) {
+        if (size.type == 't') {
+          return size.file_id;
+        }
+      }
+      break;
+    case MessageSticker::ID:
+      return td_->stickers_manager_->get_sticker_thumbnail_file_id(
+          static_cast<const MessageSticker *>(content)->file_id);
+    case MessageVideo::ID:
+      return td_->videos_manager_->get_video_thumbnail_file_id(static_cast<const MessageVideo *>(content)->file_id);
+    case MessageVideoNote::ID:
+      return td_->video_notes_manager_->get_video_note_thumbnail_file_id(
+          static_cast<const MessageVideoNote *>(content)->file_id);
+    case MessageVoiceNote::ID:
+      return FileId();
+    default:
+      break;
+  }
+  return FileId();
+}
+
+vector<FileId> MessagesManager::get_message_file_ids(const Message *message) const {
+  auto content = message->content.get();
+  switch (content->get_id()) {
+    case MessagePhoto::ID:
+      return transform(static_cast<const MessagePhoto *>(content)->photo.photos,
+                       [](auto &size) { return size.file_id; });
+    case MessageAnimation::ID:
+    case MessageAudio::ID:
+    case MessageDocument::ID:
+    case MessageSticker::ID:
+    case MessageVideo::ID:
+    case MessageVideoNote::ID:
+    case MessageVoiceNote::ID: {
+      vector<FileId> result;
+      result.reserve(2);
+      FileId file_id = get_message_content_file_id(content);
+      if (file_id.is_valid()) {
+        result.push_back(file_id);
+      }
+      FileId thumbnail_file_id = get_message_content_thumbnail_file_id(content);
+      if (file_id.is_valid()) {
+        result.push_back(thumbnail_file_id);
+      }
+      return result;
+    }
+    default:
+      return {};
+  }
+}
+
+void MessagesManager::cancel_send_message_query(DialogId dialog_id, unique_ptr<Message> &m) {
+  CHECK(m != nullptr);
+  CHECK(m->content != nullptr);
+  CHECK(m->message_id.is_yet_unsent());
+  LOG(INFO) << "Cancel send message query for " << m->message_id;
+
+  auto file_id = get_message_content_file_id(m->content.get());
+  if (file_id.is_valid()) {
+    auto it = being_uploaded_files_.find(file_id);
+    if (it != being_uploaded_files_.end()) {
+      LOG(INFO) << "Cancel upload file " << file_id << " for " << m->message_id;
+      td_->file_manager_->upload(file_id, nullptr, 0, 0);
+      being_uploaded_files_.erase(it);
+    }
+  }
+
+  auto thumbnail_file_id = get_message_content_thumbnail_file_id(m->content.get());
+  if (thumbnail_file_id.is_valid()) {
+    auto it = being_uploaded_thumbnails_.find(thumbnail_file_id);
+    if (it != being_uploaded_thumbnails_.end()) {
+      LOG(INFO) << "Cancel upload thumbnail file " << thumbnail_file_id << " for " << m->message_id;
+      td_->file_manager_->upload(thumbnail_file_id, nullptr, 0, 0);
+      being_uploaded_thumbnails_.erase(it);
+    }
+  }
+
+  if (!m->send_query_ref.empty()) {
+    LOG(INFO) << "Cancel send query for " << m->message_id;
+    cancel_query(m->send_query_ref);
+    m->send_query_ref = NetQueryRef();
+  }
+
+  if (m->send_message_logevent_id != 0) {
+    LOG(INFO) << "Delete send message log event for " << m->message_id;
+    BinlogHelper::erase(G()->td_db()->get_binlog(), m->send_message_logevent_id);
+    m->send_message_logevent_id = 0;
+  }
+
+  if (m->reply_to_message_id.is_valid() && !m->reply_to_message_id.is_yet_unsent()) {
+    auto it = replied_by_yet_unsent_messages_.find({dialog_id, m->reply_to_message_id});
+    CHECK(it != replied_by_yet_unsent_messages_.end());
+    it->second--;
+    CHECK(it->second >= 0);
+    if (it->second == 0) {
+      replied_by_yet_unsent_messages_.erase(it);
+    }
+  }
+
+  if (m->media_album_id != 0) {
+    send_closure_later(actor_id(this), &MessagesManager::on_upload_message_media_finished, m->media_album_id, dialog_id,
+                       m->message_id, Status::OK());
+  }
+
+  if (G()->parameters().use_file_db) {  // ResourceManager::Mode::Baseline
+    auto queue_id = get_sequence_dispatcher_id(dialog_id, m->content->get_id());
+    if (queue_id & 1) {
+      auto queue_it = yet_unsent_media_queues_.find(queue_id);
+      if (queue_it != yet_unsent_media_queues_.end()) {
+        auto &queue = queue_it->second;
+        LOG(INFO) << "Delete " << m->message_id << " from queue " << queue_id;
+        queue.erase(m->message_id.get());
+        if (queue.empty()) {
+          yet_unsent_media_queues_.erase(queue_it);
+        } else {
+          on_yet_unsent_media_queue_updated(dialog_id);
+        }
+      }
+    }
+  }
+}
+
+bool MessagesManager::is_message_auto_read(DialogId dialog_id, bool is_outgoing, bool only_content) const {
+  switch (dialog_id.get_type()) {
+    case DialogType::User: {
+      auto user_id = dialog_id.get_user_id();
+      if (user_id == td_->contacts_manager_->get_my_id("is_message_auto_read")) {
+        return true;
+      }
+      if (is_outgoing && td_->contacts_manager_->is_user_bot(user_id)) {
+        return true;
+      }
+      return false;
+    }
+    case DialogType::Chat:
+      // TODO auto_read message content and messages sent to group with bots only
+      return false;
+    case DialogType::Channel: {
+      if (only_content) {
+        return false;
+      }
+      auto channel_type = td_->contacts_manager_->get_channel_type(dialog_id.get_channel_id());
+      return channel_type != ChannelType::Megagroup;
+    }
+    case DialogType::SecretChat:
+      return false;
+    case DialogType::None:
+      return false;
+    default:
+      UNREACHABLE();
+      return false;
+  }
+}
+
+void MessagesManager::add_message_dependencies(Dependencies &dependencies, DialogId dialog_id, const Message *m) {
+  dependencies.user_ids.insert(m->sender_user_id);
+  dependencies.user_ids.insert(m->via_bot_user_id);
+  if (m->forward_info != nullptr) {
+    dependencies.user_ids.insert(m->forward_info->sender_user_id);
+    if (m->forward_info->dialog_id.is_valid() && dependencies.dialog_ids.insert(m->forward_info->dialog_id).second) {
+      add_dialog_dependencies(dependencies, m->forward_info->dialog_id);
+    }
+    if (m->forward_info->from_dialog_id.is_valid() &&
+        dependencies.dialog_ids.insert(m->forward_info->from_dialog_id).second) {
+      add_dialog_dependencies(dependencies, m->forward_info->from_dialog_id);
+    }
+  }
+  switch (m->content->get_id()) {
+    case MessageText::ID: {
+      auto content = static_cast<const MessageText *>(m->content.get());
+      for (auto &entity : content->text.entities) {
+        if (entity.user_id.is_valid()) {
+          dependencies.user_ids.insert(entity.user_id);
+        }
+      }
+      dependencies.web_page_ids.insert(content->web_page_id);
+      break;
+    }
+    case MessageAnimation::ID:
+      break;
+    case MessageAudio::ID:
+      break;
+    case MessageContact::ID: {
+      auto content = static_cast<const MessageContact *>(m->content.get());
+      dependencies.user_ids.insert(content->contact.get_user_id());
+      break;
+    }
+    case MessageDocument::ID:
+      break;
+    case MessageGame::ID: {
+      auto content = static_cast<const MessageGame *>(m->content.get());
+      dependencies.user_ids.insert(content->game.get_bot_user_id());
+      break;
+    }
+    case MessageInvoice::ID:
+      break;
+    case MessageLiveLocation::ID:
+      break;
+    case MessageLocation::ID:
+      break;
+    case MessagePhoto::ID:
+      break;
+    case MessageSticker::ID:
+      break;
+    case MessageVenue::ID:
+      break;
+    case MessageVideo::ID:
+      break;
+    case MessageVideoNote::ID:
+      break;
+    case MessageVoiceNote::ID:
+      break;
+    case MessageChatCreate::ID: {
+      auto content = static_cast<const MessageChatCreate *>(m->content.get());
+      dependencies.user_ids.insert(content->participant_user_ids.begin(), content->participant_user_ids.end());
+      break;
+    }
+    case MessageChatChangeTitle::ID:
+      break;
+    case MessageChatChangePhoto::ID:
+      break;
+    case MessageChatDeletePhoto::ID:
+      break;
+    case MessageChatDeleteHistory::ID:
+      break;
+    case MessageChatAddUsers::ID: {
+      auto content = static_cast<const MessageChatAddUsers *>(m->content.get());
+      dependencies.user_ids.insert(content->user_ids.begin(), content->user_ids.end());
+      break;
+    }
+    case MessageChatJoinedByLink::ID:
+      break;
+    case MessageChatDeleteUser::ID: {
+      auto content = static_cast<const MessageChatDeleteUser *>(m->content.get());
+      dependencies.user_ids.insert(content->user_id);
+      break;
+    }
+    case MessageChatMigrateTo::ID: {
+      auto content = static_cast<const MessageChatMigrateTo *>(m->content.get());
+      dependencies.channel_ids.insert(content->migrated_to_channel_id);
+      break;
+    }
+    case MessageChannelCreate::ID:
+      break;
+    case MessageChannelMigrateFrom::ID: {
+      auto content = static_cast<const MessageChannelMigrateFrom *>(m->content.get());
+      dependencies.chat_ids.insert(content->migrated_from_chat_id);
+      break;
+    }
+    case MessagePinMessage::ID:
+      break;
+    case MessageGameScore::ID:
+      break;
+    case MessageScreenshotTaken::ID:
+      break;
+    case MessageChatSetTtl::ID:
+      break;
+    case MessageUnsupported::ID:
+      break;
+    case MessageCall::ID:
+      break;
+    case MessagePaymentSuccessful::ID:
+      break;
+    case MessageContactRegistered::ID:
+      break;
+    case MessageExpiredPhoto::ID:
+      break;
+    case MessageExpiredVideo::ID:
+      break;
+    case MessageCustomServiceAction::ID:
+      break;
+    case MessageWebsiteConnected::ID:
+      break;
+    default:
+      UNREACHABLE();
+      break;
+  }
+}
+
+void MessagesManager::add_dialog_dependencies(Dependencies &dependencies, DialogId dialog_id) {
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      dependencies.user_ids.insert(dialog_id.get_user_id());
+      break;
+    case DialogType::Chat:
+      dependencies.chat_ids.insert(dialog_id.get_chat_id());
+      break;
+    case DialogType::Channel:
+      dependencies.channel_ids.insert(dialog_id.get_channel_id());
+      break;
+    case DialogType::SecretChat:
+      dependencies.secret_chat_ids.insert(dialog_id.get_secret_chat_id());
+      break;
+    case DialogType::None:
+      break;
+    default:
+      UNREACHABLE();
+  }
+}
+
+void MessagesManager::resolve_dependencies_force(const Dependencies &dependencies) {
+  for (auto user_id : dependencies.user_ids) {
+    if (user_id.is_valid() && !td_->contacts_manager_->have_user_force(user_id)) {
+      LOG(ERROR) << "Can't find " << user_id;
+    }
+  }
+  for (auto chat_id : dependencies.chat_ids) {
+    if (chat_id.is_valid() && !td_->contacts_manager_->have_chat_force(chat_id)) {
+      LOG(ERROR) << "Can't find " << chat_id;
+    }
+  }
+  for (auto channel_id : dependencies.channel_ids) {
+    if (channel_id.is_valid() && !td_->contacts_manager_->have_channel_force(channel_id)) {
+      LOG(ERROR) << "Can't find " << channel_id;
+    }
+  }
+  for (auto secret_chat_id : dependencies.secret_chat_ids) {
+    if (secret_chat_id.is_valid() && !td_->contacts_manager_->have_secret_chat_force(secret_chat_id)) {
+      LOG(ERROR) << "Can't find " << secret_chat_id;
+    }
+  }
+  for (auto dialog_id : dependencies.dialog_ids) {
+    if (dialog_id.is_valid() && !have_dialog_force(dialog_id)) {
+      LOG(ERROR) << "Can't find " << dialog_id;
+      force_create_dialog(dialog_id, "resolve_dependencies_force");
+    }
+  }
+  for (auto web_page_id : dependencies.web_page_ids) {
+    if (web_page_id.is_valid()) {
+      td_->web_pages_manager_->have_web_page_force(web_page_id);
+    }
+  }
+}
+
+class MessagesManager::SendMessageLogEvent {
+ public:
+  DialogId dialog_id;
+  const Message *m_in;
+  unique_ptr<Message> m_out;
+
+  SendMessageLogEvent() : dialog_id(), m_in(nullptr) {
+  }
+
+  SendMessageLogEvent(DialogId dialog_id, const Message *m) : dialog_id(dialog_id), m_in(m) {
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(dialog_id, storer);
+    td::store(*m_in, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(dialog_id, parser);
+    CHECK(m_out == nullptr);
+    m_out = make_unique<Message>();
+    td::parse(*m_out, parser);
+  }
+};
+
+Result<MessageId> MessagesManager::send_message(DialogId dialog_id, MessageId reply_to_message_id,
+                                                bool disable_notification, bool from_background,
+                                                tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                                                tl_object_ptr<td_api::InputMessageContent> &&input_message_content) {
+  if (input_message_content == nullptr) {
+    return Status::Error(5, "Can't send message without content");
+  }
+
+  LOG(INFO) << "Begin to send message to " << dialog_id << " in reply to " << reply_to_message_id;
+  if (input_message_content->get_id() == td_api::inputMessageForwarded::ID) {
+    auto input_message = static_cast<const td_api::inputMessageForwarded *>(input_message_content.get());
+    return forward_message(dialog_id, DialogId(input_message->from_chat_id_), MessageId(input_message->message_id_),
+                           disable_notification, from_background, input_message->in_game_share_);
+  }
+
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return Status::Error(5, "Chat not found");
+  }
+
+  TRY_STATUS(can_send_message(dialog_id));
+  TRY_RESULT(message_reply_markup, get_dialog_reply_markup(dialog_id, std::move(reply_markup)));
+  TRY_RESULT(message_content, process_input_message_content(dialog_id, std::move(input_message_content)));
+
+  // there must be no errors after get_message_to_send call
+
+  bool need_update_dialog_pos = false;
+  Message *m = get_message_to_send(
+      d, get_reply_to_message_id(d, reply_to_message_id), disable_notification, from_background,
+      dup_message_content(dialog_id, message_content.content.get(), false), &need_update_dialog_pos);
+  m->reply_markup = std::move(message_reply_markup);
+  m->via_bot_user_id = message_content.via_bot_user_id;
+  m->disable_web_page_preview = message_content.disable_web_page_preview;
+  m->clear_draft = message_content.clear_draft;
+  if (message_content.ttl > 0) {
+    m->ttl = message_content.ttl;
+    m->is_content_secret = is_secret_message_content(m->ttl, m->content->get_id());
+  }
+
+  send_update_new_message(d, m, true);
+  if (need_update_dialog_pos) {
+    send_update_chat_last_message(d, "send_message");
+  }
+
+  if (message_content.clear_draft) {
+    update_dialog_draft_message(d, nullptr, false, true);
+  }
+
+  auto message_id = m->message_id;
+  save_send_message_logevent(dialog_id, m);
+  do_send_message(dialog_id, m);
+  return message_id;
+}
+
+Result<MessagesManager::InputMessageContent> MessagesManager::process_input_message_content(
+    DialogId dialog_id, tl_object_ptr<td_api::InputMessageContent> &&input_message_content) const {
+  if (input_message_content == nullptr) {
+    return Status::Error(5, "Can't send message without content");
+  }
+
+  bool is_secret = dialog_id.get_type() == DialogType::SecretChat;
+  int32 message_type = input_message_content->get_id();
+
+  bool have_file = true;
+  // TODO: send from secret chat to common
+  Result<FileId> r_file_id;
+  tl_object_ptr<td_api::inputThumbnail> input_thumbnail;
+  vector<FileId> sticker_file_ids;
+  switch (message_type) {
+    case td_api::inputMessageAnimation::ID: {
+      auto input_message = static_cast<td_api::inputMessageAnimation *>(input_message_content.get());
+      r_file_id = td_->file_manager_->get_input_file_id(FileType::Animation, input_message->animation_, dialog_id,
+                                                        false, is_secret, true);
+      input_thumbnail = std::move(input_message->thumbnail_);
+      break;
+    }
+    case td_api::inputMessageAudio::ID: {
+      auto input_message = static_cast<td_api::inputMessageAudio *>(input_message_content.get());
+      r_file_id =
+          td_->file_manager_->get_input_file_id(FileType::Audio, input_message->audio_, dialog_id, false, is_secret);
+      input_thumbnail = std::move(input_message->album_cover_thumbnail_);
+      break;
+    }
+    case td_api::inputMessageDocument::ID: {
+      auto input_message = static_cast<td_api::inputMessageDocument *>(input_message_content.get());
+      r_file_id = td_->file_manager_->get_input_file_id(FileType::Document, input_message->document_, dialog_id, false,
+                                                        is_secret, true);
+      input_thumbnail = std::move(input_message->thumbnail_);
+      break;
+    }
+    case td_api::inputMessagePhoto::ID: {
+      auto input_message = static_cast<td_api::inputMessagePhoto *>(input_message_content.get());
+      r_file_id =
+          td_->file_manager_->get_input_file_id(FileType::Photo, input_message->photo_, dialog_id, false, is_secret);
+      input_thumbnail = std::move(input_message->thumbnail_);
+      if (!input_message->added_sticker_file_ids_.empty()) {
+        sticker_file_ids =
+            td_->stickers_manager_->get_attached_sticker_file_ids(input_message->added_sticker_file_ids_);
+      }
+      break;
+    }
+    case td_api::inputMessageSticker::ID: {
+      auto input_message = static_cast<td_api::inputMessageSticker *>(input_message_content.get());
+      r_file_id = td_->file_manager_->get_input_file_id(FileType::Sticker, input_message->sticker_, dialog_id, false,
+                                                        is_secret);
+      input_thumbnail = std::move(input_message->thumbnail_);
+      break;
+    }
+    case td_api::inputMessageVideo::ID: {
+      auto input_message = static_cast<td_api::inputMessageVideo *>(input_message_content.get());
+      r_file_id =
+          td_->file_manager_->get_input_file_id(FileType::Video, input_message->video_, dialog_id, false, is_secret);
+      input_thumbnail = std::move(input_message->thumbnail_);
+      if (!input_message->added_sticker_file_ids_.empty()) {
+        sticker_file_ids =
+            td_->stickers_manager_->get_attached_sticker_file_ids(input_message->added_sticker_file_ids_);
+      }
+      break;
+    }
+    case td_api::inputMessageVideoNote::ID: {
+      auto input_message = static_cast<td_api::inputMessageVideoNote *>(input_message_content.get());
+      r_file_id = td_->file_manager_->get_input_file_id(FileType::VideoNote, input_message->video_note_, dialog_id,
+                                                        false, is_secret);
+      input_thumbnail = std::move(input_message->thumbnail_);
+      break;
+    }
+    case td_api::inputMessageVoiceNote::ID: {
+      auto input_message = static_cast<td_api::inputMessageVoiceNote *>(input_message_content.get());
+      r_file_id = td_->file_manager_->get_input_file_id(FileType::VoiceNote, input_message->voice_note_, dialog_id,
+                                                        false, is_secret);
+      break;
+    }
+    default:
+      have_file = false;
+      break;
+  }
+  // TODO is path of files must be stored in bytes instead of UTF-8 string?
+
+  FileId file_id;
+  FileView file_view;
+  string file_name;
+  string mime_type;
+  if (have_file) {
+    if (r_file_id.is_error()) {
+      return Status::Error(7, r_file_id.error().message());
+    }
+    file_id = r_file_id.ok();
+    CHECK(file_id.is_valid());
+    file_view = td_->file_manager_->get_file_view(file_id);
+    auto suggested_name = file_view.suggested_name();
+    const PathView path_view(suggested_name);
+    file_name = path_view.file_name().str();
+    mime_type = MimeType::from_extension(path_view.extension());
+  }
+
+  FileId thumbnail_file_id;
+  PhotoSize thumbnail;
+  if (input_thumbnail != nullptr) {
+    auto r_thumbnail_file_id =
+        td_->file_manager_->get_input_thumbnail_file_id(input_thumbnail->thumbnail_, dialog_id, is_secret);
+    if (r_thumbnail_file_id.is_error()) {
+      LOG(WARNING) << "Ignore thumbnail file: " << r_thumbnail_file_id.error().message();
+    } else {
+      thumbnail_file_id = r_thumbnail_file_id.ok();
+      CHECK(thumbnail_file_id.is_valid());
+
+      thumbnail.type = 't';
+      thumbnail.dimensions = get_dimensions(input_thumbnail->width_, input_thumbnail->height_);
+      thumbnail.file_id = thumbnail_file_id;
+
+      FileView thumbnail_file_view = td_->file_manager_->get_file_view(thumbnail_file_id);
+      if (thumbnail_file_view.has_remote_location()) {
+        // TODO td->file_manager_->delete_remote_location(thumbnail_file_id);
+      }
+    }
+  }
+
+  LOG(INFO) << "Send file " << file_id << " and thumbnail " << thumbnail_file_id;
+
+  bool disable_web_page_preview = false;
+  bool clear_draft = false;
+  unique_ptr<MessageContent> content;
+  UserId via_bot_user_id;
+  int32 ttl = 0;
+  bool is_bot = td_->auth_manager_->is_bot();
+  switch (message_type) {
+    case td_api::inputMessageText::ID: {
+      TRY_RESULT(input_message_text, process_input_message_text(dialog_id, std::move(input_message_content), is_bot));
+      disable_web_page_preview = input_message_text.disable_web_page_preview;
+      clear_draft = input_message_text.clear_draft;
+
+      WebPageId web_page_id;
+      if (!disable_web_page_preview &&
+          (dialog_id.get_type() != DialogType::Channel ||
+           td_->contacts_manager_->get_channel_status(dialog_id.get_channel_id()).can_add_web_page_previews())) {
+        web_page_id = td_->web_pages_manager_->get_web_page_by_url(
+            get_first_url(input_message_text.text.text, input_message_text.text.entities));
+      }
+      content = make_unique<MessageText>(std::move(input_message_text.text), web_page_id);
+      break;
+    }
+    case td_api::inputMessageAnimation::ID: {
+      auto input_animation = static_cast<td_api::inputMessageAnimation *>(input_message_content.get());
+
+      TRY_RESULT(caption, process_input_caption(dialog_id, std::move(input_animation->caption_), is_bot));
+
+      td_->animations_manager_->create_animation(
+          file_id, thumbnail, std::move(file_name), std::move(mime_type), input_animation->duration_,
+          get_dimensions(input_animation->width_, input_animation->height_), false);
+
+      content = make_unique<MessageAnimation>(file_id, std::move(caption));
+      break;
+    }
+    case td_api::inputMessageAudio::ID: {
+      auto input_audio = static_cast<td_api::inputMessageAudio *>(input_message_content.get());
+
+      if (!clean_input_string(input_audio->title_)) {
+        return Status::Error(400, "Audio title must be encoded in UTF-8");
+      }
+      if (!clean_input_string(input_audio->performer_)) {
+        return Status::Error(400, "Audio performer must be encoded in UTF-8");
+      }
+      TRY_RESULT(caption, process_input_caption(dialog_id, std::move(input_audio->caption_), is_bot));
+
+      td_->audios_manager_->create_audio(file_id, thumbnail, std::move(file_name), std::move(mime_type),
+                                         input_audio->duration_, std::move(input_audio->title_),
+                                         std::move(input_audio->performer_), false);
+
+      content = make_unique<MessageAudio>(file_id, std::move(caption));
+      break;
+    }
+    case td_api::inputMessageDocument::ID: {
+      auto input_document = static_cast<td_api::inputMessageDocument *>(input_message_content.get());
+
+      TRY_RESULT(caption, process_input_caption(dialog_id, std::move(input_document->caption_), is_bot));
+
+      td_->documents_manager_->create_document(file_id, thumbnail, std::move(file_name), std::move(mime_type), false);
+
+      content = make_unique<MessageDocument>(file_id, std::move(caption));
+      break;
+    }
+    case td_api::inputMessagePhoto::ID: {
+      auto input_photo = static_cast<td_api::inputMessagePhoto *>(input_message_content.get());
+
+      TRY_RESULT(caption, process_input_caption(dialog_id, std::move(input_photo->caption_), is_bot));
+      if (input_photo->width_ < 0 || input_photo->width_ > 10000) {
+        return Status::Error(400, "Wrong photo width");
+      }
+      if (input_photo->height_ < 0 || input_photo->height_ > 10000) {
+        return Status::Error(400, "Wrong photo height");
+      }
+      ttl = input_photo->ttl_;
+
+      auto message_photo = make_unique<MessagePhoto>();
+
+      if (file_view.has_remote_location() && !file_view.remote_location().is_web()) {
+        message_photo->photo.id = file_view.remote_location().get_id();
+      }
+      message_photo->photo.date = G()->unix_time();
+
+      PhotoSize s;
+      s.type = 'i';
+      s.dimensions = get_dimensions(input_photo->width_, input_photo->height_);
+      s.size = static_cast<int32>(file_view.size());
+      s.file_id = file_id;
+
+      if (thumbnail_file_id.is_valid()) {
+        message_photo->photo.photos.push_back(thumbnail);
+      }
+
+      message_photo->photo.photos.push_back(s);
+
+      message_photo->photo.has_stickers = !sticker_file_ids.empty();
+      message_photo->photo.sticker_file_ids = std::move(sticker_file_ids);
+
+      message_photo->caption = std::move(caption);
+
+      content = std::move(message_photo);
+      break;
+    }
+    case td_api::inputMessageSticker::ID: {
+      auto input_sticker = static_cast<td_api::inputMessageSticker *>(input_message_content.get());
+      td_->stickers_manager_->create_sticker(
+          file_id, thumbnail, get_dimensions(input_sticker->width_, input_sticker->height_), true, nullptr, nullptr);
+
+      content = make_unique<MessageSticker>(file_id);
+      break;
+    }
+    case td_api::inputMessageVideo::ID: {
+      auto input_video = static_cast<td_api::inputMessageVideo *>(input_message_content.get());
+
+      TRY_RESULT(caption, process_input_caption(dialog_id, std::move(input_video->caption_), is_bot));
+      ttl = input_video->ttl_;
+
+      bool has_stickers = !sticker_file_ids.empty();
+      td_->videos_manager_->create_video(file_id, thumbnail, has_stickers, std::move(sticker_file_ids),
+                                         std::move(file_name), std::move(mime_type), input_video->duration_,
+                                         get_dimensions(input_video->width_, input_video->height_),
+                                         input_video->supports_streaming_, false);
+
+      content = make_unique<MessageVideo>(file_id, std::move(caption));
+      break;
+    }
+    case td_api::inputMessageVideoNote::ID: {
+      auto input_video_note = static_cast<td_api::inputMessageVideoNote *>(input_message_content.get());
+
+      auto length = input_video_note->length_;
+      if (length < 0 || length >= 640) {
+        return Status::Error(400, "Wrong video note length");
+      }
+
+      td_->video_notes_manager_->create_video_note(file_id, thumbnail, input_video_note->duration_,
+                                                   get_dimensions(length, length), false);
+
+      content = make_unique<MessageVideoNote>(file_id, false);
+      break;
+    }
+    case td_api::inputMessageVoiceNote::ID: {
+      auto input_voice_note = static_cast<td_api::inputMessageVoiceNote *>(input_message_content.get());
+
+      TRY_RESULT(caption, process_input_caption(dialog_id, std::move(input_voice_note->caption_), is_bot));
+
+      td_->voice_notes_manager_->create_voice_note(file_id, std::move(mime_type), input_voice_note->duration_,
+                                                   std::move(input_voice_note->waveform_), false);
+
+      content = make_unique<MessageVoiceNote>(file_id, std::move(caption), false);
+      break;
+    }
+    case td_api::inputMessageLocation::ID: {
+      TRY_RESULT(location, process_input_message_location(std::move(input_message_content)));
+      if (location.second == 0) {
+        content = make_unique<MessageLocation>(std::move(location.first));
+      } else {
+        content = make_unique<MessageLiveLocation>(std::move(location.first), location.second);
+      }
+      break;
+    }
+    case td_api::inputMessageVenue::ID: {
+      TRY_RESULT(venue, process_input_message_venue(std::move(input_message_content)));
+      content = make_unique<MessageVenue>(std::move(venue));
+      break;
+    }
+    case td_api::inputMessageContact::ID: {
+      TRY_RESULT(contact, process_input_message_contact(std::move(input_message_content)));
+      content = make_unique<MessageContact>(std::move(contact));
+      break;
+    }
+    case td_api::inputMessageGame::ID: {
+      TRY_RESULT(game, process_input_message_game(std::move(input_message_content)));
+      via_bot_user_id = game.get_bot_user_id();
+      if (via_bot_user_id == td_->contacts_manager_->get_my_id("send_message")) {
+        via_bot_user_id = UserId();
+      }
+
+      content = make_unique<MessageGame>(std::move(game));
+      break;
+    }
+    case td_api::inputMessageInvoice::ID: {
+      if (!is_bot) {
+        return Status::Error(400, "Invoices can be sent only by bots");
+      }
+
+      auto input_message_invoice = move_tl_object_as<td_api::inputMessageInvoice>(input_message_content);
+      if (!clean_input_string(input_message_invoice->title_)) {
+        return Status::Error(400, "Invoice title must be encoded in UTF-8");
+      }
+      if (!clean_input_string(input_message_invoice->description_)) {
+        return Status::Error(400, "Invoice description must be encoded in UTF-8");
+      }
+      if (!clean_input_string(input_message_invoice->photo_url_)) {
+        return Status::Error(400, "Invoice photo URL must be encoded in UTF-8");
+      }
+      if (!clean_input_string(input_message_invoice->start_parameter_)) {
+        return Status::Error(400, "Invoice bot start parameter must be encoded in UTF-8");
+      }
+      if (!clean_input_string(input_message_invoice->provider_token_)) {
+        return Status::Error(400, "Invoice provider token must be encoded in UTF-8");
+      }
+      if (!clean_input_string(input_message_invoice->provider_data_)) {
+        return Status::Error(400, "Invoice provider data must be encoded in UTF-8");
+      }
+      if (!clean_input_string(input_message_invoice->invoice_->currency_)) {
+        return Status::Error(400, "Invoice currency must be encoded in UTF-8");
+      }
+
+      auto message_invoice = make_unique<MessageInvoice>();
+      message_invoice->title = std::move(input_message_invoice->title_);
+      message_invoice->description = std::move(input_message_invoice->description_);
+
+      auto r_http_url = parse_url(input_message_invoice->photo_url_);
+      if (r_http_url.is_error()) {
+        message_invoice->photo.id = -2;
+      } else {
+        auto url = r_http_url.ok().get_url();
+        auto r_invoice_file_id = td_->file_manager_->from_persistent_id(url, FileType::Temp);
+        if (r_invoice_file_id.is_error()) {
+          LOG(ERROR) << "Can't register url " << url;
+          message_invoice->photo.id = -2;
+        } else {
+          auto invoice_file_id = r_invoice_file_id.move_as_ok();
+
+          PhotoSize s;
+          s.type = 'u';
+          s.dimensions = get_dimensions(input_message_invoice->photo_width_, input_message_invoice->photo_height_);
+          s.size = input_message_invoice->photo_size_;  // TODO use invoice_file_id size
+          s.file_id = invoice_file_id;
+
+          message_invoice->photo.photos.push_back(s);
+        }
+      }
+      message_invoice->start_parameter = std::move(input_message_invoice->start_parameter_);
+
+      message_invoice->invoice.currency = std::move(input_message_invoice->invoice_->currency_);
+      message_invoice->invoice.price_parts.reserve(input_message_invoice->invoice_->price_parts_.size());
+      int64 total_amount = 0;
+      const int64 MAX_AMOUNT = 9999'9999'9999;
+      for (auto &price : input_message_invoice->invoice_->price_parts_) {
+        if (!clean_input_string(price->label_)) {
+          return Status::Error(400, "Invoice price label must be encoded in UTF-8");
+        }
+        message_invoice->invoice.price_parts.emplace_back(std::move(price->label_), price->amount_);
+        if (price->amount_ < -MAX_AMOUNT || price->amount_ > MAX_AMOUNT) {
+          return Status::Error(400, "Too big amount of currency specified");
+        }
+        total_amount += price->amount_;
+      }
+      if (total_amount <= 0) {
+        return Status::Error(400, "Total price must be positive");
+      }
+      if (total_amount > MAX_AMOUNT) {
+        return Status::Error(400, "Total price is too big");
+      }
+      message_invoice->total_amount = total_amount;
+
+      message_invoice->invoice.is_test = input_message_invoice->invoice_->is_test_;
+      message_invoice->invoice.need_name = input_message_invoice->invoice_->need_name_;
+      message_invoice->invoice.need_phone_number = input_message_invoice->invoice_->need_phone_number_;
+      message_invoice->invoice.need_email_address = input_message_invoice->invoice_->need_email_address_;
+      message_invoice->invoice.need_shipping_address = input_message_invoice->invoice_->need_shipping_address_;
+      message_invoice->invoice.send_phone_number_to_provider =
+          input_message_invoice->invoice_->send_phone_number_to_provider_;
+      message_invoice->invoice.send_email_address_to_provider =
+          input_message_invoice->invoice_->send_email_address_to_provider_;
+      message_invoice->invoice.is_flexible = input_message_invoice->invoice_->is_flexible_;
+      if (message_invoice->invoice.send_phone_number_to_provider) {
+        message_invoice->invoice.need_phone_number = true;
+      }
+      if (message_invoice->invoice.send_email_address_to_provider) {
+        message_invoice->invoice.need_email_address = true;
+      }
+      if (message_invoice->invoice.is_flexible) {
+        message_invoice->invoice.need_shipping_address = true;
+      }
+
+      message_invoice->payload = std::move(input_message_invoice->payload_);
+      message_invoice->provider_token = std::move(input_message_invoice->provider_token_);
+      message_invoice->provider_data = std::move(input_message_invoice->provider_data_);
+
+      content = std::move(message_invoice);
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+  if (ttl < 0 || ttl > MAX_PRIVATE_MESSAGE_TTL) {
+    return Status::Error(10, "Wrong message TTL specified");
+  }
+  if (ttl > 0 && dialog_id.get_type() != DialogType::User) {
+    return Status::Error(10, "Message TTL can be specified only in private chats");
+  }
+
+  TRY_STATUS(can_send_message_content(dialog_id, content.get(), false));
+
+  return InputMessageContent{std::move(content), disable_web_page_preview, clear_draft, ttl, via_bot_user_id};
+}
+
+Result<vector<MessageId>> MessagesManager::send_message_group(
+    DialogId dialog_id, MessageId reply_to_message_id, bool disable_notification, bool from_background,
+    vector<tl_object_ptr<td_api::InputMessageContent>> &&input_message_contents) {
+  if (input_message_contents.size() > MAX_GROUPED_MESSAGES) {
+    return Status::Error(4, "Too much messages to send as an album");
+  }
+  if (input_message_contents.empty()) {
+    return Status::Error(4, "There is no messages to send");
+  }
+
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return Status::Error(5, "Chat not found");
+  }
+
+  TRY_STATUS(can_send_message(dialog_id));
+
+  vector<std::pair<unique_ptr<MessageContent>, int32>> message_contents;
+  for (auto &input_message_content : input_message_contents) {
+    TRY_RESULT(message_content, process_input_message_content(dialog_id, std::move(input_message_content)));
+    if (!is_allowed_media_group_content(message_content.content->get_id())) {
+      return Status::Error(5, "Wrong message content type");
+    }
+
+    message_contents.emplace_back(std::move(message_content.content), message_content.ttl);
+  }
+
+  reply_to_message_id = get_reply_to_message_id(d, reply_to_message_id);
+
+  int64 media_album_id = 0;
+  if (message_contents.size() > 1) {
+    do {
+      media_album_id = Random::secure_int64();
+    } while (media_album_id >= 0 || pending_message_group_sends_.count(media_album_id) != 0);
+  }
+
+  // there must be no errors after get_message_to_send calls
+
+  vector<MessageId> result;
+  bool need_update_dialog_pos = false;
+  for (auto &message_content : message_contents) {
+    Message *m = get_message_to_send(d, reply_to_message_id, disable_notification, from_background,
+                                     dup_message_content(dialog_id, message_content.first.get(), false),
+                                     &need_update_dialog_pos);
+    result.push_back(m->message_id);
+    auto ttl = message_content.second;
+    if (ttl > 0) {
+      m->ttl = ttl;
+      m->is_content_secret = is_secret_message_content(m->ttl, m->content->get_id());
+    }
+    m->media_album_id = media_album_id;
+
+    save_send_message_logevent(dialog_id, m);
+    do_send_message(dialog_id, m);
+
+    send_update_new_message(d, m, true);
+  }
+
+  if (need_update_dialog_pos) {
+    send_update_chat_last_message(d, "send_message_group");
+  }
+
+  return result;
+}
+
+void MessagesManager::save_send_message_logevent(DialogId dialog_id, Message *m) {
+  if (!G()->parameters().use_message_db) {
+    return;
+  }
+
+  CHECK(m != nullptr);
+  LOG(INFO) << "Save " << FullMessageId(dialog_id, m->message_id) << " to binlog";
+  auto logevent = SendMessageLogEvent(dialog_id, m);
+  auto storer = LogEventStorerImpl<SendMessageLogEvent>(logevent);
+  CHECK(m->send_message_logevent_id == 0);
+  m->send_message_logevent_id =
+      BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::SendMessage, storer);
+}
+
+void MessagesManager::do_send_message(DialogId dialog_id, Message *m, vector<int> bad_parts) {
+  LOG(INFO) << "Do send " << FullMessageId(dialog_id, m->message_id);
+  bool is_secret = dialog_id.get_type() == DialogType::SecretChat;
+
+  if (m->media_album_id != 0 && bad_parts.empty() && !is_secret) {
+    auto &request = pending_message_group_sends_[m->media_album_id];
+    request.dialog_id = dialog_id;
+    request.message_ids.push_back(m->message_id);
+    request.is_finished.push_back(false);
+
+    request.results.push_back(Status::OK());
+  }
+
+  auto content = m->content.get();
+  auto content_type = content->get_id();
+  if (content_type == MessageText::ID) {
+    auto message_text = static_cast<const MessageText *>(content);
+
+    int64 random_id = begin_send_message(dialog_id, m);
+    if (is_secret) {
+      auto layer = td_->contacts_manager_->get_secret_chat_layer(dialog_id.get_secret_chat_id());
+      send_closure(td_->create_net_actor<SendSecretMessageActor>(), &SendSecretMessageActor::send, dialog_id,
+                   m->reply_to_random_id, m->ttl, message_text->text.text,
+                   get_secret_input_media(content, nullptr, BufferSlice(), layer),
+                   get_input_secret_message_entities(message_text->text.entities), m->via_bot_user_id,
+                   m->media_album_id, random_id);
+    } else {
+      send_closure(td_->create_net_actor<SendMessageActor>(), &SendMessageActor::send, get_message_flags(m), dialog_id,
+                   m->reply_to_message_id, get_input_reply_markup(m->reply_markup),
+                   get_input_message_entities(td_->contacts_manager_.get(), message_text->text.entities),
+                   message_text->text.text, random_id, &m->send_query_ref,
+                   get_sequence_dispatcher_id(dialog_id, content_type));
+    }
+    return;
+  }
+
+  FileId file_id = get_message_content_file_id(content);
+  FileView file_view = td_->file_manager_->get_file_view(file_id);
+  FileId thumbnail_file_id = get_message_content_thumbnail_file_id(content);
+  if (is_secret) {
+    auto layer = td_->contacts_manager_->get_secret_chat_layer(dialog_id.get_secret_chat_id());
+    auto secret_input_media = get_secret_input_media(content, nullptr, BufferSlice(), layer);
+    if (secret_input_media.empty()) {
+      CHECK(file_view.is_encrypted());
+      CHECK(file_id.is_valid());
+      being_uploaded_files_[file_id] = {FullMessageId(dialog_id, m->message_id), thumbnail_file_id};
+      LOG(INFO) << "Ask to upload encrypted file " << file_id;
+      // need to call resume_upload synchronously to make upload process consistent with being_uploaded_files_
+      td_->file_manager_->resume_upload(file_id, std::move(bad_parts), upload_media_callback_, 1, m->message_id.get());
+    } else {
+      on_secret_message_media_uploaded(dialog_id, m, std::move(secret_input_media), FileId(), FileId());
+    }
+  } else {
+    auto input_media = get_input_media(content, nullptr, nullptr, m->ttl);
+    if (input_media == nullptr) {
+      if (content_type == MessagePhoto::ID) {
+        thumbnail_file_id = FileId();
+      }
+
+      CHECK(file_id.is_valid());
+      being_uploaded_files_[file_id] = {FullMessageId(dialog_id, m->message_id), thumbnail_file_id};
+      LOG(INFO) << "Ask to upload file " << file_id;
+      // need to call resume_upload synchronously to make upload process consistent with being_uploaded_files_
+      td_->file_manager_->resume_upload(file_id, std::move(bad_parts), upload_media_callback_, 1, m->message_id.get());
+    } else {
+      on_message_media_uploaded(dialog_id, m, std::move(input_media), FileId(), FileId());
+    }
+  }
+}
+
+void MessagesManager::on_message_media_uploaded(DialogId dialog_id, Message *m,
+                                                tl_object_ptr<telegram_api::InputMedia> &&input_media, FileId file_id,
+                                                FileId thumbnail_file_id) {
+  CHECK(m != nullptr);
+  CHECK(input_media != nullptr);
+  if (m->media_album_id == 0) {
+    on_media_message_ready_to_send(
+        dialog_id, m->message_id,
+        PromiseCreator::lambda([this, dialog_id, input_media = std::move(input_media), file_id,
+                                thumbnail_file_id](Result<Message *> result) mutable {
+          if (result.is_error() || G()->close_flag()) {
+            return;
+          }
+
+          auto m = result.move_as_ok();
+          CHECK(m != nullptr);
+          CHECK(input_media != nullptr);
+
+          auto caption = get_message_content_caption(m->content.get());
+
+          LOG(INFO) << "Send media from " << m->message_id << " in " << dialog_id << " in reply to "
+                    << m->reply_to_message_id;
+          int64 random_id = begin_send_message(dialog_id, m);
+          send_closure(td_->create_net_actor<SendMediaActor>(), &SendMediaActor::send, file_id, thumbnail_file_id,
+                       get_message_flags(m), dialog_id, m->reply_to_message_id, get_input_reply_markup(m->reply_markup),
+                       get_input_message_entities(td_->contacts_manager_.get(), caption.entities), caption.text,
+                       std::move(input_media), random_id, &m->send_query_ref,
+                       get_sequence_dispatcher_id(dialog_id, m->content->get_id()));
+        }));
+  } else {
+    switch (input_media->get_id()) {
+      case telegram_api::inputMediaUploadedDocument::ID:
+        static_cast<telegram_api::inputMediaUploadedDocument *>(input_media.get())->flags_ |=
+            telegram_api::inputMediaUploadedDocument::NOSOUND_VIDEO_MASK;
+      // fallthrough
+      case telegram_api::inputMediaUploadedPhoto::ID:
+      case telegram_api::inputMediaDocumentExternal::ID:
+      case telegram_api::inputMediaPhotoExternal::ID:
+        LOG(INFO) << "Upload media from " << m->message_id << " in " << dialog_id;
+        td_->create_handler<UploadMediaQuery>()->send(dialog_id, m->message_id, file_id, thumbnail_file_id,
+                                                      std::move(input_media));
+        break;
+      case telegram_api::inputMediaDocument::ID:
+      case telegram_api::inputMediaPhoto::ID:
+        send_closure_later(actor_id(this), &MessagesManager::on_upload_message_media_finished, m->media_album_id,
+                           dialog_id, m->message_id, Status::OK());
+        break;
+      default:
+        LOG(ERROR) << "Have wrong input media " << to_string(input_media);
+        send_closure_later(actor_id(this), &MessagesManager::on_upload_message_media_finished, m->media_album_id,
+                           dialog_id, m->message_id, Status::Error(400, "Wrong input media"));
+    }
+  }
+}
+
+void MessagesManager::on_secret_message_media_uploaded(DialogId dialog_id, Message *m,
+                                                       SecretInputMedia &&secret_input_media, FileId file_id,
+                                                       FileId thumbnail_file_id) {
+  CHECK(m != nullptr);
+  CHECK(!secret_input_media.empty());
+  /*
+  if (m->media_album_id != 0) {
+    switch (secret_input_media->input_file_->get_id()) {
+      case telegram_api::inputEncryptedFileUploaded::ID:
+      case telegram_api::inputEncryptedFileBigUploaded::ID:
+        LOG(INFO) << "Upload media from " << m->message_id << " in " << dialog_id;
+        return td_->create_handler<UploadEncryptedMediaQuery>()->send(dialog_id, m->message_id, std::move(secret_input_media));
+      case telegram_api::inputEncryptedFile::ID:
+        return send_closure_later(actor_id(this), &MessagesManager::on_upload_message_media_finished, m->media_album_id,
+                           dialog_id, m->message_id, Status::OK());
+      default:
+        LOG(ERROR) << "Have wrong secret input media " << to_string(secret_input_media->input_file_);
+        return send_closure_later(actor_id(this), &MessagesManager::on_upload_message_media_finished, m->media_album_id,
+                           dialog_id, m->message_id, Status::Error(400, "Wrong input media"));
+  }
+*/
+  // TODO use file_id, thumbnail_file_id, invalidate partial remote location for file_id in case of failed upload
+  // even message has already been deleted
+  on_media_message_ready_to_send(
+      dialog_id, m->message_id,
+      PromiseCreator::lambda(
+          [this, dialog_id, secret_input_media = std::move(secret_input_media)](Result<Message *> result) mutable {
+            if (result.is_error() || G()->close_flag()) {
+              return;
+            }
+
+            auto m = result.move_as_ok();
+            CHECK(m != nullptr);
+            CHECK(!secret_input_media.empty());
+            LOG(INFO) << "Send secret media from " << m->message_id << " in " << dialog_id << " in reply to "
+                      << m->reply_to_message_id;
+            int64 random_id = begin_send_message(dialog_id, m);
+            send_closure(td_->create_net_actor<SendSecretMessageActor>(), &SendSecretMessageActor::send, dialog_id,
+                         m->reply_to_random_id, m->ttl, "", std::move(secret_input_media),
+                         vector<tl_object_ptr<secret_api::MessageEntity>>(), m->via_bot_user_id, m->media_album_id,
+                         random_id);
+          }));
+}
+
+void MessagesManager::on_upload_message_media_success(DialogId dialog_id, MessageId message_id,
+                                                      tl_object_ptr<telegram_api::MessageMedia> &&media) {
+  Dialog *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+
+  Message *m = get_message(d, message_id);
+  if (m == nullptr) {
+    // message has already been deleted by the user or sent to inaccessible channel
+    // don't need to send error to the user, because the message has already been deleted
+    // and there is nothing to be deleted from the server
+    LOG(INFO) << "Fail to send already deleted by the user or sent to inaccessible chat "
+              << FullMessageId{dialog_id, message_id};
+    return;
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    return;  // the message should be deleted soon
+  }
+
+  auto content = get_message_content(get_message_content_caption(m->content.get()), std::move(media), dialog_id, false,
+                                     UserId(), nullptr);
+
+  update_message_content(dialog_id, m, m->content, std::move(content), true);
+
+  auto input_media = get_input_media(m->content.get(), nullptr, nullptr, m->ttl);
+  Status result;
+  if (input_media == nullptr) {
+    result = Status::Error(400, "Failed to upload file");
+  }
+
+  send_closure_later(actor_id(this), &MessagesManager::on_upload_message_media_finished, m->media_album_id, dialog_id,
+                     message_id, std::move(result));
+}
+
+void MessagesManager::on_upload_message_media_file_part_missing(DialogId dialog_id, MessageId message_id,
+                                                                int bad_part) {
+  Dialog *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+
+  Message *m = get_message(d, message_id);
+  if (m == nullptr) {
+    // message has already been deleted by the user or sent to inaccessible channel
+    // don't need to send error to the user, because the message has already been deleted
+    // and there is nothing to be deleted from the server
+    LOG(INFO) << "Fail to send already deleted by the user or sent to inaccessible chat "
+              << FullMessageId{dialog_id, message_id};
+    return;
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    // LOG(ERROR) << "Found " << m->message_id << " in inaccessible " << dialog_id;
+    // dump_debug_message_op(get_dialog(dialog_id), 5);
+    return;  // the message should be deleted soon
+  }
+
+  CHECK(dialog_id.get_type() != DialogType::SecretChat);
+
+  do_send_message(dialog_id, m, {bad_part});
+}
+
+void MessagesManager::on_upload_message_media_fail(DialogId dialog_id, MessageId message_id, Status error) {
+  Dialog *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+
+  Message *m = get_message(d, message_id);
+  if (m == nullptr) {
+    // message has already been deleted by the user or sent to inaccessible channel
+    // don't need to send error to the user, because the message has already been deleted
+    // and there is nothing to be deleted from the server
+    LOG(INFO) << "Fail to send already deleted by the user or sent to inaccessible chat "
+              << FullMessageId{dialog_id, message_id};
+    return;
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    // LOG(ERROR) << "Found " << m->message_id << " in inaccessible " << dialog_id;
+    // dump_debug_message_op(get_dialog(dialog_id), 5);
+    return;  // the message should be deleted soon
+  }
+
+  CHECK(dialog_id.get_type() != DialogType::SecretChat);
+
+  send_closure_later(actor_id(this), &MessagesManager::on_upload_message_media_finished, m->media_album_id, dialog_id,
+                     message_id, std::move(error));
+}
+
+void MessagesManager::on_upload_message_media_finished(int64 media_album_id, DialogId dialog_id, MessageId message_id,
+                                                       Status result) {
+  CHECK(media_album_id < 0);
+  auto it = pending_message_group_sends_.find(media_album_id);
+  if (it == pending_message_group_sends_.end()) {
+    // the group may be already sent or failed to be sent
+    return;
+  }
+  auto &request = it->second;
+  CHECK(request.dialog_id == dialog_id);
+  auto message_it = std::find(request.message_ids.begin(), request.message_ids.end(), message_id);
+  CHECK(message_it != request.message_ids.end());
+  auto pos = static_cast<size_t>(message_it - request.message_ids.begin());
+
+  if (request.is_finished[pos]) {
+    return;
+  }
+  LOG(INFO) << "Finish to upload media of " << message_id << " in " << dialog_id << " from group " << media_album_id;
+
+  request.results[pos] = std::move(result);
+  request.is_finished[pos] = true;
+  request.finished_count++;
+
+  if (request.finished_count == request.message_ids.size() || request.results[pos].is_error()) {
+    // send later, because some messages may be being deleted now
+    for (auto request_message_id : request.message_ids) {
+      LOG(INFO) << "Send on_media_message_ready_to_send for " << request_message_id << " in " << dialog_id;
+      send_closure_later(actor_id(this), &MessagesManager::on_media_message_ready_to_send, dialog_id,
+                         request_message_id,
+                         PromiseCreator::lambda([actor_id = actor_id(this)](Result<Message *> result) mutable {
+                           if (result.is_error() || G()->close_flag()) {
+                             return;
+                           }
+
+                           auto m = result.move_as_ok();
+                           CHECK(m != nullptr);
+                           send_closure_later(actor_id, &MessagesManager::do_send_message_group, m->media_album_id);
+                         }));
+    }
+  }
+}
+
+void MessagesManager::do_send_message_group(int64 media_album_id) {
+  CHECK(media_album_id < 0);
+  auto it = pending_message_group_sends_.find(media_album_id);
+  if (it == pending_message_group_sends_.end()) {
+    // the group may be already sent or failed to be sent
+    return;
+  }
+  auto &request = it->second;
+
+  auto dialog_id = request.dialog_id;
+  Dialog *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+
+  auto default_status = can_send_message(dialog_id);
+  bool success = default_status.is_ok();
+  vector<int64> random_ids;
+  vector<tl_object_ptr<telegram_api::inputSingleMedia>> input_single_media;
+  MessageId reply_to_message_id;
+  int32 flags = 0;
+  for (size_t i = 0; i < request.message_ids.size(); i++) {
+    auto *m = get_message(d, request.message_ids[i]);
+    if (m == nullptr) {
+      // skip deleted messages
+      random_ids.push_back(0);
+      continue;
+    }
+
+    reply_to_message_id = m->reply_to_message_id;
+    flags = get_message_flags(m);
+
+    random_ids.push_back(begin_send_message(dialog_id, m));
+    auto caption = get_message_content_caption(m->content.get());
+    auto input_media = get_input_media(m->content.get(), nullptr, nullptr, m->ttl);
+    auto entities = get_input_message_entities(td_->contacts_manager_.get(), caption.entities);
+    int32 input_single_media_flags = 0;
+    if (!entities.empty()) {
+      input_single_media_flags |= telegram_api::inputSingleMedia::ENTITIES_MASK;
+    }
+
+    input_single_media.push_back(make_tl_object<telegram_api::inputSingleMedia>(
+        input_single_media_flags, std::move(input_media), random_ids.back(), caption.text, std::move(entities)));
+    if (request.results[i].is_error()) {
+      success = false;
+    }
+  }
+
+  if (!success) {
+    if (default_status.is_ok()) {
+      default_status = Status::Error(400, "Group send failed");
+    }
+    for (size_t i = 0; i < random_ids.size(); i++) {
+      if (random_ids[i] != 0) {
+        on_send_message_fail(random_ids[i],
+                             request.results[i].is_error() ? std::move(request.results[i]) : default_status.clone());
+      }
+    }
+    pending_message_group_sends_.erase(it);
+    return;
+  }
+  CHECK(request.finished_count == request.message_ids.size());
+  pending_message_group_sends_.erase(it);
+
+  LOG(INFO) << "Begin to send media group " << media_album_id << " to " << dialog_id;
+
+  if (input_single_media.empty()) {
+    LOG(INFO) << "Media group " << media_album_id << " from " << dialog_id << " is empty";
+  }
+  send_closure(td_->create_net_actor<SendMultiMediaActor>(), &SendMultiMediaActor::send, flags, dialog_id,
+               reply_to_message_id, std::move(input_single_media),
+               get_sequence_dispatcher_id(dialog_id, MessagePhoto::ID));
+}
+
+void MessagesManager::on_media_message_ready_to_send(DialogId dialog_id, MessageId message_id,
+                                                     Promise<Message *> &&promise) {
+  LOG(INFO) << "Ready to send " << message_id << " to " << dialog_id;
+  CHECK(promise);
+  if (!G()->parameters().use_file_db) {  // ResourceManager::Mode::Greedy
+    auto m = get_message({dialog_id, message_id});
+    if (m != nullptr) {
+      promise.set_value(std::move(m));
+    }
+    return;
+  }
+
+  auto queue_id = get_sequence_dispatcher_id(dialog_id, MessagePhoto::ID);
+  CHECK(queue_id & 1);
+  auto &queue = yet_unsent_media_queues_[queue_id];
+  auto it = queue.find(message_id.get());
+  if (it == queue.end()) {
+    if (queue.empty()) {
+      yet_unsent_media_queues_.erase(queue_id);
+    }
+
+    LOG(INFO) << "Can't find " << message_id << " in the queue of " << dialog_id;
+    auto m = get_message({dialog_id, message_id});
+    if (m != nullptr) {
+      promise.set_value(std::move(m));
+    }
+    return;
+  }
+  if (it->second) {
+    promise.set_error(Status::Error(500, "Duplicate promise"));
+    return;
+  }
+  it->second = std::move(promise);
+
+  on_yet_unsent_media_queue_updated(dialog_id);
+}
+
+void MessagesManager::on_yet_unsent_media_queue_updated(DialogId dialog_id) {
+  auto queue_id = get_sequence_dispatcher_id(dialog_id, MessagePhoto::ID);
+  CHECK(queue_id & 1);
+  auto &queue = yet_unsent_media_queues_[queue_id];
+  LOG(INFO) << "Queue for " << dialog_id << " is updated to size of " << queue.size();
+  while (!queue.empty()) {
+    auto first_it = queue.begin();
+    if (!first_it->second) {
+      break;
+    }
+
+    auto m = get_message({dialog_id, MessageId(first_it->first)});
+    if (m != nullptr) {
+      LOG(INFO) << "Can send " << FullMessageId{dialog_id, m->message_id};
+      first_it->second.set_value(std::move(m));
+    }
+    queue.erase(first_it);
+  }
+  LOG(INFO) << "Queue for " << dialog_id << " now has size " << queue.size();
+  if (queue.empty()) {
+    yet_unsent_media_queues_.erase(queue_id);
+  }
+}
+
+Result<MessageId> MessagesManager::send_bot_start_message(UserId bot_user_id, DialogId dialog_id,
+                                                          const string &parameter) {
+  LOG(INFO) << "Begin to send bot start message to " << dialog_id;
+  if (td_->auth_manager_->is_bot()) {
+    return Status::Error(5, "Bot can't send start message to another bot");
+  }
+
+  TRY_RESULT(bot_data, td_->contacts_manager_->get_bot_data(bot_user_id));
+
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return Status::Error(5, "Chat not found");
+  }
+
+  bool is_chat_with_bot = false;
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      if (dialog_id.get_user_id() != bot_user_id) {
+        return Status::Error(5, "Can't send start message to a private chat other than chat with the bot");
+      }
+      is_chat_with_bot = true;
+      break;
+    case DialogType::Chat: {
+      if (!bot_data.can_join_groups) {
+        return Status::Error(5, "Bot can't join groups");
+      }
+
+      auto chat_id = dialog_id.get_chat_id();
+      if (!td_->contacts_manager_->have_input_peer_chat(chat_id, AccessRights::Write)) {
+        return Status::Error(3, "Can't access the chat");
+      }
+      auto status = td_->contacts_manager_->get_chat_status(chat_id);
+      if (!status.can_invite_users()) {
+        return Status::Error(3, "Need administrator rights to invite a bot to the group chat");
+      }
+      break;
+    }
+    case DialogType::Channel: {
+      auto channel_id = dialog_id.get_channel_id();
+      if (!td_->contacts_manager_->have_input_peer_channel(channel_id, AccessRights::Write)) {
+        return Status::Error(3, "Can't access the chat");
+      }
+      switch (td_->contacts_manager_->get_channel_type(channel_id)) {
+        case ChannelType::Megagroup:
+          if (!bot_data.can_join_groups) {
+            return Status::Error(5, "The bot can't join groups");
+          }
+          break;
+        case ChannelType::Broadcast:
+          return Status::Error(3, "Bots can't be invited to channel chats. Add them as administrators instead");
+        case ChannelType::Unknown:
+        default:
+          UNREACHABLE();
+      }
+      auto status = td_->contacts_manager_->get_channel_status(channel_id);
+      if (!status.can_invite_users()) {
+        return Status::Error(3, "Need administrator rights to invite a bot to the supergroup chat");
+      }
+      break;
+    }
+    case DialogType::SecretChat:
+      return Status::Error(5, "Can't send bot start message to a secret chat");
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+  string text = "/start";
+  if (!is_chat_with_bot) {
+    text += '@';
+    text += bot_data.username;
+  }
+
+  bool need_update_dialog_pos = false;
+  Message *m = get_message_to_send(
+      d, MessageId(), false, false,
+      make_unique<MessageText>(
+          FormattedText{text, vector<MessageEntity>{MessageEntity(MessageEntity::Type::BotCommand, 0,
+                                                                  narrow_cast<int32>(text.size()))}},
+          WebPageId()),
+      &need_update_dialog_pos);
+
+  send_update_new_message(d, m, true);
+  if (need_update_dialog_pos) {
+    send_update_chat_last_message(d, "send_bot_start_message");
+  }
+
+  save_send_bot_start_message_logevent(bot_user_id, dialog_id, parameter, m);
+  do_send_bot_start_message(bot_user_id, dialog_id, parameter, m);
+  return m->message_id;
+}
+
+class MessagesManager::SendBotStartMessageLogEvent {
+ public:
+  UserId bot_user_id;
+  DialogId dialog_id;
+  string parameter;
+  const Message *m_in = nullptr;
+  unique_ptr<Message> m_out;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(bot_user_id, storer);
+    td::store(dialog_id, storer);
+    td::store(parameter, storer);
+    td::store(*m_in, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(bot_user_id, parser);
+    td::parse(dialog_id, parser);
+    td::parse(parameter, parser);
+    CHECK(m_out == nullptr);
+    m_out = make_unique<Message>();
+    td::parse(*m_out, parser);
+  }
+};
+
+void MessagesManager::save_send_bot_start_message_logevent(UserId bot_user_id, DialogId dialog_id,
+                                                           const string &parameter, Message *m) {
+  if (!G()->parameters().use_message_db) {
+    return;
+  }
+
+  CHECK(m != nullptr);
+  LOG(INFO) << "Save " << FullMessageId(dialog_id, m->message_id) << " to binlog";
+  SendBotStartMessageLogEvent logevent;
+  logevent.bot_user_id = bot_user_id;
+  logevent.dialog_id = dialog_id;
+  logevent.parameter = parameter;
+  logevent.m_in = m;
+  auto storer = LogEventStorerImpl<SendBotStartMessageLogEvent>(logevent);
+  CHECK(m->send_message_logevent_id == 0);
+  m->send_message_logevent_id =
+      BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::SendBotStartMessage, storer);
+}
+
+void MessagesManager::do_send_bot_start_message(UserId bot_user_id, DialogId dialog_id, const string &parameter,
+                                                Message *m) {
+  LOG(INFO) << "Do send bot start " << FullMessageId(dialog_id, m->message_id) << " to bot " << bot_user_id;
+
+  int64 random_id = begin_send_message(dialog_id, m);
+  telegram_api::object_ptr<telegram_api::InputPeer> input_peer = dialog_id.get_type() == DialogType::User
+                                                                     ? make_tl_object<telegram_api::inputPeerEmpty>()
+                                                                     : get_input_peer(dialog_id, AccessRights::Write);
+  if (input_peer == nullptr) {
+    return on_send_message_fail(random_id, Status::Error(400, "Have no info about the chat"));
+  }
+  auto bot_input_user = td_->contacts_manager_->get_input_user(bot_user_id);
+  if (bot_input_user == nullptr) {
+    return on_send_message_fail(random_id, Status::Error(400, "Have no info about the bot"));
+  }
+
+  m->send_query_ref = td_->create_handler<StartBotQuery>()->send(std::move(bot_input_user), dialog_id,
+                                                                 std::move(input_peer), parameter, random_id);
+}
+
+Result<MessageId> MessagesManager::send_inline_query_result_message(DialogId dialog_id, MessageId reply_to_message_id,
+                                                                    bool disable_notification, bool from_background,
+                                                                    int64 query_id, const string &result_id) {
+  LOG(INFO) << "Begin to send inline query result message to " << dialog_id << " in reply to " << reply_to_message_id;
+
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return Status::Error(5, "Chat not found");
+  }
+
+  TRY_STATUS(can_send_message(dialog_id));
+  bool to_secret = false;
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+      // ok
+      break;
+    case DialogType::Channel: {
+      auto channel_status = td_->contacts_manager_->get_channel_status(dialog_id.get_channel_id());
+      if (!channel_status.can_use_inline_bots()) {
+        return Status::Error(400, "Can't use inline bots in the chat");
+      }
+      break;
+    }
+    case DialogType::SecretChat:
+      to_secret = true;
+      // ok
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+
+  const MessageContent *message_content;
+  const ReplyMarkup *reply_markup;
+  bool disable_web_page_preview;
+  std::tie(message_content, reply_markup, disable_web_page_preview) =
+      td_->inline_queries_manager_->get_inline_message_content(query_id, result_id);
+  if (message_content == nullptr) {
+    return Status::Error(5, "Inline query result not found");
+  }
+
+  TRY_STATUS(can_send_message_content(dialog_id, message_content, false));
+
+  bool need_update_dialog_pos = false;
+  Message *m =
+      get_message_to_send(d, get_reply_to_message_id(d, reply_to_message_id), disable_notification, from_background,
+                          dup_message_content(dialog_id, message_content, false), &need_update_dialog_pos);
+  m->via_bot_user_id = td_->inline_queries_manager_->get_inline_bot_user_id(query_id);
+  if (reply_markup != nullptr && !to_secret) {
+    m->reply_markup = make_unique<ReplyMarkup>(*reply_markup);
+  }
+  m->disable_web_page_preview = disable_web_page_preview;
+  m->clear_draft = true;
+
+  update_dialog_draft_message(d, nullptr, false, !need_update_dialog_pos);
+
+  send_update_new_message(d, m, true);
+  if (need_update_dialog_pos) {
+    send_update_chat_last_message(d, "send_inline_query_result_message");
+  }
+
+  if (to_secret) {
+    save_send_message_logevent(dialog_id, m);
+    auto message_id = m->message_id;
+    do_send_message(dialog_id, m);
+    return message_id;
+  }
+
+  save_send_inline_query_result_message_logevent(dialog_id, m, query_id, result_id);
+  do_send_inline_query_result_message(dialog_id, m, query_id, result_id);
+  return m->message_id;
+}
+
+class MessagesManager::SendInlineQueryResultMessageLogEvent {
+ public:
+  DialogId dialog_id;
+  int64 query_id;
+  string result_id;
+  const Message *m_in = nullptr;
+  unique_ptr<Message> m_out;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(dialog_id, storer);
+    td::store(query_id, storer);
+    td::store(result_id, storer);
+    td::store(*m_in, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(dialog_id, parser);
+    td::parse(query_id, parser);
+    td::parse(result_id, parser);
+    CHECK(m_out == nullptr);
+    m_out = make_unique<Message>();
+    td::parse(*m_out, parser);
+  }
+};
+
+void MessagesManager::save_send_inline_query_result_message_logevent(DialogId dialog_id, Message *m, int64 query_id,
+                                                                     const string &result_id) {
+  if (!G()->parameters().use_message_db) {
+    return;
+  }
+
+  CHECK(m != nullptr);
+  LOG(INFO) << "Save " << FullMessageId(dialog_id, m->message_id) << " to binlog";
+  SendInlineQueryResultMessageLogEvent logevent;
+  logevent.dialog_id = dialog_id;
+  logevent.query_id = query_id;
+  logevent.result_id = result_id;
+  logevent.m_in = m;
+  auto storer = LogEventStorerImpl<SendInlineQueryResultMessageLogEvent>(logevent);
+  CHECK(m->send_message_logevent_id == 0);
+  m->send_message_logevent_id =
+      BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::SendInlineQueryResultMessage, storer);
+}
+
+void MessagesManager::do_send_inline_query_result_message(DialogId dialog_id, Message *m, int64 query_id,
+                                                          const string &result_id) {
+  LOG(INFO) << "Do send inline query result " << FullMessageId(dialog_id, m->message_id);
+
+  int64 random_id = begin_send_message(dialog_id, m);
+  m->send_query_ref = td_->create_handler<SendInlineBotResultQuery>()->send(
+      get_message_flags(m), dialog_id, m->reply_to_message_id, random_id, query_id, result_id);
+}
+
+bool MessagesManager::can_edit_message(DialogId dialog_id, const Message *m, bool is_editing,
+                                       bool only_reply_markup) const {
+  if (m == nullptr) {
+    return false;
+  }
+  if (m->message_id.is_yet_unsent()) {
+    return false;
+  }
+  if (m->message_id.is_local()) {
+    return false;
+  }
+  if (m->forward_info != nullptr) {
+    return false;
+  }
+
+  bool is_bot = td_->auth_manager_->is_bot();
+  if (m->had_reply_markup) {
+    return false;
+  }
+  if (!is_bot && m->reply_markup != nullptr) {
+    return false;
+  }
+  if (m->reply_markup != nullptr && m->reply_markup->type != ReplyMarkup::Type::InlineKeyboard) {
+    return false;
+  }
+
+  auto my_id = td_->contacts_manager_->get_my_id("can_edit_message");
+  if (m->via_bot_user_id.is_valid() && m->via_bot_user_id != my_id) {
+    return false;
+  }
+
+  DialogId my_dialog_id(my_id);
+  bool has_edit_time_limit = !(is_bot && m->is_outgoing) && dialog_id != my_dialog_id;
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      if (!m->is_outgoing && dialog_id != my_dialog_id) {
+        return false;
+      }
+      break;
+    case DialogType::Chat:
+      if (!m->is_outgoing) {
+        return false;
+      }
+      break;
+    case DialogType::Channel: {
+      if (m->via_bot_user_id.is_valid()) {
+        // outgoing via_bot messages can always be edited
+        break;
+      }
+
+      auto channel_id = dialog_id.get_channel_id();
+      auto channel_status = td_->contacts_manager_->get_channel_status(channel_id);
+      if (m->is_channel_post) {
+        if (!channel_status.can_edit_messages() && !(channel_status.can_post_messages() && m->is_outgoing)) {
+          return false;
+        }
+      } else {
+        if (!m->is_outgoing) {
+          return false;
+        }
+        if (channel_status.can_pin_messages()) {
+          has_edit_time_limit = false;
+        }
+      }
+      break;
+    }
+    case DialogType::SecretChat:
+      return false;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      return false;
+  }
+
+  const int32 DEFAULT_EDIT_TIME_LIMIT = 2 * 86400;
+  int32 edit_time_limit = G()->shared_config().get_option_integer("edit_time_limit", DEFAULT_EDIT_TIME_LIMIT);
+  if (has_edit_time_limit && G()->unix_time_cached() - m->date >= edit_time_limit + (is_editing ? 300 : 0)) {
+    return false;
+  }
+
+  switch (m->content->get_id()) {
+    case MessageAnimation::ID:
+    case MessageAudio::ID:
+    case MessageDocument::ID:
+    case MessageGame::ID:
+    case MessagePhoto::ID:
+    case MessageText::ID:
+    case MessageVideo::ID:
+    case MessageVoiceNote::ID:
+      return true;
+    case MessageLiveLocation::ID: {
+      if (td_->auth_manager_->is_bot() && only_reply_markup) {
+        // there is no caption to edit, but bot can edit inline reply_markup
+        return true;
+      }
+      return G()->unix_time_cached() - m->date < static_cast<const MessageLiveLocation *>(m->content.get())->period;
+    }
+    case MessageContact::ID:
+    case MessageLocation::ID:
+    case MessageSticker::ID:
+    case MessageVenue::ID:
+    case MessageVideoNote::ID:
+      // there is no caption to edit, but bot can edit inline reply_markup
+      return td_->auth_manager_->is_bot() && only_reply_markup;
+    case MessageInvoice::ID:
+    case MessageUnsupported::ID:
+    case MessageChatCreate::ID:
+    case MessageChatChangeTitle::ID:
+    case MessageChatChangePhoto::ID:
+    case MessageChatDeletePhoto::ID:
+    case MessageChatDeleteHistory::ID:
+    case MessageChatAddUsers::ID:
+    case MessageChatJoinedByLink::ID:
+    case MessageChatDeleteUser::ID:
+    case MessageChatMigrateTo::ID:
+    case MessageChannelCreate::ID:
+    case MessageChannelMigrateFrom::ID:
+    case MessagePinMessage::ID:
+    case MessageGameScore::ID:
+    case MessageScreenshotTaken::ID:
+    case MessageChatSetTtl::ID:
+    case MessageCall::ID:
+    case MessagePaymentSuccessful::ID:
+    case MessageContactRegistered::ID:
+    case MessageExpiredPhoto::ID:
+    case MessageExpiredVideo::ID:
+    case MessageCustomServiceAction::ID:
+    case MessageWebsiteConnected::ID:
+      return false;
+    default:
+      UNREACHABLE();
+  }
+
+  return false;
+}
+
+bool MessagesManager::is_broadcast_channel(DialogId dialog_id) const {
+  if (dialog_id.get_type() != DialogType::Channel) {
+    return false;
+  }
+
+  return td_->contacts_manager_->get_channel_type(dialog_id.get_channel_id()) == ChannelType::Broadcast;
+}
+
+void MessagesManager::edit_message_text(FullMessageId full_message_id,
+                                        tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                                        tl_object_ptr<td_api::InputMessageContent> &&input_message_content,
+                                        Promise<Unit> &&promise) {
+  if (input_message_content == nullptr) {
+    return promise.set_error(Status::Error(5, "Can't edit message without new content"));
+  }
+  int32 new_message_content_type = input_message_content->get_id();
+  if (new_message_content_type != td_api::inputMessageText::ID) {
+    return promise.set_error(Status::Error(5, "Input message content type must be InputMessageText"));
+  }
+
+  LOG(INFO) << "Begin to edit text of " << full_message_id;
+  auto dialog_id = full_message_id.get_dialog_id();
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return promise.set_error(Status::Error(5, "Chat not found"));
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Edit)) {
+    return promise.set_error(Status::Error(5, "Can't access the chat"));
+  }
+
+  auto message_id = full_message_id.get_message_id();
+  const Message *message = get_message_force(d, message_id);
+  if (message == nullptr) {
+    return promise.set_error(Status::Error(5, "Message not found"));
+  }
+
+  if (!can_edit_message(dialog_id, message, true)) {
+    return promise.set_error(Status::Error(5, "Message can't be edited"));
+  }
+
+  int32 old_message_content_type = message->content->get_id();
+  if (old_message_content_type != MessageText::ID && old_message_content_type != MessageGame::ID) {
+    return promise.set_error(Status::Error(5, "There is no text in the message to edit"));
+  }
+
+  auto r_input_message_text =
+      process_input_message_text(dialog_id, std::move(input_message_content), td_->auth_manager_->is_bot());
+  if (r_input_message_text.is_error()) {
+    return promise.set_error(r_input_message_text.move_as_error());
+  }
+  InputMessageText input_message_text = r_input_message_text.move_as_ok();
+
+  auto r_new_reply_markup = get_reply_markup(std::move(reply_markup), td_->auth_manager_->is_bot(), true, false,
+                                             !is_broadcast_channel(dialog_id));
+  if (r_new_reply_markup.is_error()) {
+    return promise.set_error(r_new_reply_markup.move_as_error());
+  }
+  auto input_reply_markup = get_input_reply_markup(r_new_reply_markup.ok());
+  int32 flags = 0;
+  if (input_message_text.disable_web_page_preview) {
+    flags |= SEND_MESSAGE_FLAG_DISABLE_WEB_PAGE_PREVIEW;
+  }
+
+  send_closure(td_->create_net_actor<EditMessageActor>(std::move(promise)), &EditMessageActor::send, flags, dialog_id,
+               message_id, input_message_text.text.text,
+               get_input_message_entities(td_->contacts_manager_.get(), input_message_text.text.entities), nullptr,
+               std::move(input_reply_markup), get_sequence_dispatcher_id(dialog_id, -1));
+}
+
+void MessagesManager::edit_message_live_location(FullMessageId full_message_id,
+                                                 tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                                                 tl_object_ptr<td_api::location> &&input_location,
+                                                 Promise<Unit> &&promise) {
+  LOG(INFO) << "Begin to edit live location of " << full_message_id;
+  auto dialog_id = full_message_id.get_dialog_id();
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return promise.set_error(Status::Error(5, "Chat not found"));
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Edit)) {
+    return promise.set_error(Status::Error(5, "Can't access the chat"));
+  }
+
+  auto message_id = full_message_id.get_message_id();
+  const Message *message = get_message_force(d, message_id);
+  if (message == nullptr) {
+    return promise.set_error(Status::Error(5, "Message not found"));
+  }
+
+  if (!can_edit_message(dialog_id, message, true)) {
+    return promise.set_error(Status::Error(5, "Message can't be edited"));
+  }
+
+  int32 old_message_content_type = message->content->get_id();
+  if (old_message_content_type != MessageLiveLocation::ID) {
+    return promise.set_error(Status::Error(5, "There is no live location in the message to edit"));
+  }
+
+  Location location(input_location);
+  if (location.empty() && input_location != nullptr) {
+    return promise.set_error(Status::Error(400, "Wrong location specified"));
+  }
+
+  auto r_new_reply_markup = get_reply_markup(std::move(reply_markup), td_->auth_manager_->is_bot(), true, false,
+                                             !is_broadcast_channel(dialog_id));
+  if (r_new_reply_markup.is_error()) {
+    return promise.set_error(r_new_reply_markup.move_as_error());
+  }
+  auto input_reply_markup = get_input_reply_markup(r_new_reply_markup.ok());
+
+  int32 flags = 0;
+  if (location.empty()) {
+    flags |= telegram_api::messages_editMessage::STOP_GEO_LIVE_MASK;
+  }
+  send_closure(td_->create_net_actor<EditMessageActor>(std::move(promise)), &EditMessageActor::send, flags, dialog_id,
+               message_id, string(), vector<tl_object_ptr<telegram_api::MessageEntity>>(),
+               location.empty() ? nullptr : location.get_input_geo_point(), std::move(input_reply_markup),
+               get_sequence_dispatcher_id(dialog_id, -1));
+}
+
+void MessagesManager::edit_message_caption(FullMessageId full_message_id,
+                                           tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                                           tl_object_ptr<td_api::formattedText> &&input_caption,
+                                           Promise<Unit> &&promise) {
+  LOG(INFO) << "Begin to edit caption of " << full_message_id;
+
+  auto dialog_id = full_message_id.get_dialog_id();
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return promise.set_error(Status::Error(5, "Chat not found"));
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Edit)) {
+    return promise.set_error(Status::Error(5, "Can't access the chat"));
+  }
+
+  auto message_id = full_message_id.get_message_id();
+  const Message *message = get_message_force(d, message_id);
+  if (message == nullptr) {
+    return promise.set_error(Status::Error(5, "Message not found"));
+  }
+
+  if (!can_edit_message(dialog_id, message, true)) {
+    return promise.set_error(Status::Error(5, "Message can't be edited"));
+  }
+
+  if (!can_have_message_content_caption(message->content->get_id())) {
+    return promise.set_error(Status::Error(400, "There is no caption in the message to edit"));
+  }
+
+  auto r_caption = process_input_caption(dialog_id, std::move(input_caption), td_->auth_manager_->is_bot());
+  if (r_caption.is_error()) {
+    return promise.set_error(r_caption.move_as_error());
+  }
+  auto caption = r_caption.move_as_ok();
+
+  auto r_new_reply_markup = get_reply_markup(std::move(reply_markup), td_->auth_manager_->is_bot(), true, false,
+                                             !is_broadcast_channel(dialog_id));
+  if (r_new_reply_markup.is_error()) {
+    return promise.set_error(r_new_reply_markup.move_as_error());
+  }
+  auto input_reply_markup = get_input_reply_markup(r_new_reply_markup.ok());
+
+  send_closure(td_->create_net_actor<EditMessageActor>(std::move(promise)), &EditMessageActor::send, 1 << 11, dialog_id,
+               message_id, caption.text, get_input_message_entities(td_->contacts_manager_.get(), caption.entities),
+               nullptr, std::move(input_reply_markup), get_sequence_dispatcher_id(dialog_id, -1));
+}
+
+void MessagesManager::edit_message_reply_markup(FullMessageId full_message_id,
+                                                tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                                                Promise<Unit> &&promise) {
+  if (!td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(3, "Method is available only for bots"));
+  }
+
+  LOG(INFO) << "Begin to edit reply markup of " << full_message_id;
+  auto dialog_id = full_message_id.get_dialog_id();
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return promise.set_error(Status::Error(5, "Chat not found"));
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Edit)) {
+    return promise.set_error(Status::Error(5, "Can't access the chat"));
+  }
+
+  auto message_id = full_message_id.get_message_id();
+  const Message *message = get_message_force(d, message_id);
+  if (message == nullptr) {
+    return promise.set_error(Status::Error(5, "Message not found"));
+  }
+
+  if (!can_edit_message(dialog_id, message, true, true)) {
+    return promise.set_error(Status::Error(5, "Message can't be edited"));
+  }
+
+  auto r_new_reply_markup = get_reply_markup(std::move(reply_markup), td_->auth_manager_->is_bot(), true, false,
+                                             !is_broadcast_channel(dialog_id));
+  if (r_new_reply_markup.is_error()) {
+    return promise.set_error(r_new_reply_markup.move_as_error());
+  }
+  auto input_reply_markup = get_input_reply_markup(r_new_reply_markup.ok());
+  send_closure(td_->create_net_actor<EditMessageActor>(std::move(promise)), &EditMessageActor::send, 0, dialog_id,
+               message_id, string(), vector<tl_object_ptr<telegram_api::MessageEntity>>(), nullptr,
+               std::move(input_reply_markup), get_sequence_dispatcher_id(dialog_id, -1));
+}
+
+void MessagesManager::edit_inline_message_text(const string &inline_message_id,
+                                               tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                                               tl_object_ptr<td_api::InputMessageContent> &&input_message_content,
+                                               Promise<Unit> &&promise) {
+  if (!td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(3, "Method is available only for bots"));
+  }
+
+  if (input_message_content == nullptr) {
+    return promise.set_error(Status::Error(5, "Can't edit message without new content"));
+  }
+  int32 new_message_content_type = input_message_content->get_id();
+  if (new_message_content_type != td_api::inputMessageText::ID) {
+    return promise.set_error(Status::Error(5, "Input message content type must be InputMessageText"));
+  }
+
+  auto r_input_message_text =
+      process_input_message_text(DialogId(), std::move(input_message_content), td_->auth_manager_->is_bot());
+  if (r_input_message_text.is_error()) {
+    return promise.set_error(r_input_message_text.move_as_error());
+  }
+  InputMessageText input_message_text = r_input_message_text.move_as_ok();
+
+  auto r_new_reply_markup = get_reply_markup(std::move(reply_markup), td_->auth_manager_->is_bot(), true, false, true);
+  if (r_new_reply_markup.is_error()) {
+    return promise.set_error(r_new_reply_markup.move_as_error());
+  }
+
+  auto input_bot_inline_message_id = td_->inline_queries_manager_->get_input_bot_inline_message_id(inline_message_id);
+  if (input_bot_inline_message_id == nullptr) {
+    return promise.set_error(Status::Error(400, "Wrong inline message identifier specified"));
+  }
+
+  int32 flags = 0;
+  if (input_message_text.disable_web_page_preview) {
+    flags |= SEND_MESSAGE_FLAG_DISABLE_WEB_PAGE_PREVIEW;
+  }
+  td_->create_handler<EditInlineMessageQuery>(std::move(promise))
+      ->send(flags, std::move(input_bot_inline_message_id), input_message_text.text.text,
+             get_input_message_entities(td_->contacts_manager_.get(), input_message_text.text.entities), nullptr,
+             get_input_reply_markup(r_new_reply_markup.ok()));
+}
+
+void MessagesManager::edit_inline_message_live_location(const string &inline_message_id,
+                                                        tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                                                        tl_object_ptr<td_api::location> &&input_location,
+                                                        Promise<Unit> &&promise) {
+  if (!td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(3, "Method is available only for bots"));
+  }
+
+  auto r_new_reply_markup = get_reply_markup(std::move(reply_markup), td_->auth_manager_->is_bot(), true, false, true);
+  if (r_new_reply_markup.is_error()) {
+    return promise.set_error(r_new_reply_markup.move_as_error());
+  }
+
+  auto input_bot_inline_message_id = td_->inline_queries_manager_->get_input_bot_inline_message_id(inline_message_id);
+  if (input_bot_inline_message_id == nullptr) {
+    return promise.set_error(Status::Error(400, "Wrong inline message identifier specified"));
+  }
+
+  Location location(input_location);
+  if (location.empty() && input_location != nullptr) {
+    return promise.set_error(Status::Error(400, "Wrong location specified"));
+  }
+
+  int32 flags = 0;
+  if (location.empty()) {
+    flags |= telegram_api::messages_editMessage::STOP_GEO_LIVE_MASK;
+  }
+  td_->create_handler<EditInlineMessageQuery>(std::move(promise))
+      ->send(flags, std::move(input_bot_inline_message_id), "", vector<tl_object_ptr<telegram_api::MessageEntity>>(),
+             location.empty() ? nullptr : location.get_input_geo_point(),
+             get_input_reply_markup(r_new_reply_markup.ok()));
+}
+
+void MessagesManager::edit_inline_message_caption(const string &inline_message_id,
+                                                  tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                                                  tl_object_ptr<td_api::formattedText> &&input_caption,
+                                                  Promise<Unit> &&promise) {
+  if (!td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(3, "Method is available only for bots"));
+  }
+
+  auto r_caption = process_input_caption(DialogId(), std::move(input_caption), td_->auth_manager_->is_bot());
+  if (r_caption.is_error()) {
+    return promise.set_error(r_caption.move_as_error());
+  }
+  auto caption = r_caption.move_as_ok();
+
+  auto r_new_reply_markup = get_reply_markup(std::move(reply_markup), td_->auth_manager_->is_bot(), true, false, true);
+  if (r_new_reply_markup.is_error()) {
+    return promise.set_error(r_new_reply_markup.move_as_error());
+  }
+
+  auto input_bot_inline_message_id = td_->inline_queries_manager_->get_input_bot_inline_message_id(inline_message_id);
+  if (input_bot_inline_message_id == nullptr) {
+    return promise.set_error(Status::Error(400, "Wrong inline message identifier specified"));
+  }
+
+  td_->create_handler<EditInlineMessageQuery>(std::move(promise))
+      ->send(1 << 11, std::move(input_bot_inline_message_id), caption.text,
+             get_input_message_entities(td_->contacts_manager_.get(), caption.entities), nullptr,
+             get_input_reply_markup(r_new_reply_markup.ok()));
+}
+
+void MessagesManager::edit_inline_message_reply_markup(const string &inline_message_id,
+                                                       tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                                                       Promise<Unit> &&promise) {
+  if (!td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(3, "Method is available only for bots"));
+  }
+
+  auto r_new_reply_markup = get_reply_markup(std::move(reply_markup), td_->auth_manager_->is_bot(), true, false, true);
+  if (r_new_reply_markup.is_error()) {
+    return promise.set_error(r_new_reply_markup.move_as_error());
+  }
+
+  auto input_bot_inline_message_id = td_->inline_queries_manager_->get_input_bot_inline_message_id(inline_message_id);
+  if (input_bot_inline_message_id == nullptr) {
+    return promise.set_error(Status::Error(400, "Wrong inline message identifier specified"));
+  }
+
+  td_->create_handler<EditInlineMessageQuery>(std::move(promise))
+      ->send(0, std::move(input_bot_inline_message_id), string(), vector<tl_object_ptr<telegram_api::MessageEntity>>(),
+             nullptr, get_input_reply_markup(r_new_reply_markup.ok()));
+}
+
+int32 MessagesManager::get_message_flags(const Message *m) {
+  int32 flags = 0;
+  if (m->reply_to_message_id.is_valid()) {
+    flags |= SEND_MESSAGE_FLAG_IS_REPLY;
+  }
+  if (m->disable_web_page_preview) {
+    flags |= SEND_MESSAGE_FLAG_DISABLE_WEB_PAGE_PREVIEW;
+  }
+  if (m->reply_markup != nullptr) {
+    flags |= SEND_MESSAGE_FLAG_HAS_REPLY_MARKUP;
+  }
+  if (m->disable_notification) {
+    flags |= SEND_MESSAGE_FLAG_DISABLE_NOTIFICATION;
+  }
+  if (m->from_background) {
+    flags |= SEND_MESSAGE_FLAG_FROM_BACKGROUND;
+  }
+  if (m->clear_draft) {
+    flags |= SEND_MESSAGE_FLAG_CLEAR_DRAFT;
+  }
+  return flags;
+}
+
+bool MessagesManager::can_set_game_score(DialogId dialog_id, const Message *m) const {
+  if (m == nullptr) {
+    return false;
+  }
+  if (m->message_id.is_yet_unsent()) {
+    return false;
+  }
+  if (m->message_id.is_local()) {
+    return false;
+  }
+  if (m->via_bot_user_id.is_valid() && !m->is_outgoing) {
+    return false;
+  }
+
+  if (!td_->auth_manager_->is_bot()) {
+    return false;
+  }
+  if (m->reply_markup == nullptr || m->reply_markup->type != ReplyMarkup::Type::InlineKeyboard ||
+      m->reply_markup->inline_keyboard.empty()) {
+    return false;
+  }
+
+  DialogId my_dialog_id(td_->contacts_manager_->get_my_id("can_set_game_score"));
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      if (!m->is_outgoing && dialog_id != my_dialog_id) {
+        return false;
+      }
+      break;
+    case DialogType::Chat:
+      if (!m->is_outgoing) {
+        return false;
+      }
+      break;
+    case DialogType::Channel: {
+      if (m->via_bot_user_id.is_valid()) {
+        // outgoing via_bot messages can always be edited
+        break;
+      }
+      auto channel_id = dialog_id.get_channel_id();
+      auto channel_status = td_->contacts_manager_->get_channel_status(channel_id);
+      if (m->is_channel_post) {
+        if (!channel_status.can_edit_messages() && (!channel_status.can_post_messages() || !m->is_outgoing)) {
+          return false;
+        }
+      } else {
+        if (!m->is_outgoing) {
+          return false;
+        }
+      }
+      break;
+    }
+    case DialogType::SecretChat:
+      return false;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      return false;
+  }
+
+  return m->content->get_id() == MessageGame::ID;
+}
+
+void MessagesManager::set_game_score(FullMessageId full_message_id, bool edit_message, UserId user_id, int32 score,
+                                     bool force, Promise<Unit> &&promise) {
+  if (!td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(3, "Method is available only for bots"));
+  }
+
+  LOG(INFO) << "Begin to set game score of " << user_id << " in " << full_message_id;
+  auto dialog_id = full_message_id.get_dialog_id();
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return promise.set_error(Status::Error(5, "Chat not found"));
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Edit)) {
+    return promise.set_error(Status::Error(5, "Can't access the chat"));
+  }
+
+  auto message_id = full_message_id.get_message_id();
+  const Message *message = get_message_force(d, message_id);
+  if (message == nullptr) {
+    return promise.set_error(Status::Error(5, "Message not found"));
+  }
+
+  auto input_user = td_->contacts_manager_->get_input_user(user_id);
+  if (input_user == nullptr) {
+    return promise.set_error(Status::Error(400, "Wrong user identifier specified"));
+  }
+
+  if (!can_set_game_score(dialog_id, message)) {
+    return promise.set_error(Status::Error(5, "Game score can't be set"));
+  }
+
+  send_closure(td_->create_net_actor<SetGameScoreActor>(std::move(promise)), &SetGameScoreActor::send, dialog_id,
+               message_id, edit_message, std::move(input_user), score, force,
+               get_sequence_dispatcher_id(dialog_id, -1));
+}
+
+void MessagesManager::set_inline_game_score(const string &inline_message_id, bool edit_message, UserId user_id,
+                                            int32 score, bool force, Promise<Unit> &&promise) {
+  if (!td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(3, "Method is available only for bots"));
+  }
+
+  auto input_bot_inline_message_id = td_->inline_queries_manager_->get_input_bot_inline_message_id(inline_message_id);
+  if (input_bot_inline_message_id == nullptr) {
+    return promise.set_error(Status::Error(400, "Wrong inline message identifier specified"));
+  }
+
+  auto input_user = td_->contacts_manager_->get_input_user(user_id);
+  if (input_user == nullptr) {
+    return promise.set_error(Status::Error(400, "Wrong user identifier specified"));
+  }
+
+  td_->create_handler<SetInlineGameScoreQuery>(std::move(promise))
+      ->send(std::move(input_bot_inline_message_id), edit_message, std::move(input_user), score, force);
+}
+
+int64 MessagesManager::get_game_high_scores(FullMessageId full_message_id, UserId user_id, Promise<Unit> &&promise) {
+  if (!td_->auth_manager_->is_bot()) {
+    promise.set_error(Status::Error(3, "Method is available only for bots"));
+    return 0;
+  }
+
+  LOG(INFO) << "Begin to get game high scores of " << user_id << " in " << full_message_id;
+  auto dialog_id = full_message_id.get_dialog_id();
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    promise.set_error(Status::Error(5, "Chat not found"));
+    return 0;
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    promise.set_error(Status::Error(5, "Can't access the chat"));
+    return 0;
+  }
+
+  auto message_id = full_message_id.get_message_id();
+  const Message *message = get_message_force(d, message_id);
+  if (message == nullptr) {
+    promise.set_error(Status::Error(5, "Message not found"));
+    return 0;
+  }
+  if (!message_id.is_server()) {
+    promise.set_error(Status::Error(5, "Wrong message identifier specified"));
+    return 0;
+  }
+
+  auto input_user = td_->contacts_manager_->get_input_user(user_id);
+  if (input_user == nullptr) {
+    promise.set_error(Status::Error(400, "Wrong user identifier specified"));
+    return 0;
+  }
+
+  int64 random_id = 0;
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 || game_high_scores_.find(random_id) != game_high_scores_.end());
+  game_high_scores_[random_id];  // reserve place for result
+
+  td_->create_handler<GetGameHighScoresQuery>(std::move(promise))
+      ->send(dialog_id, message_id, std::move(input_user), random_id);
+  return random_id;
+}
+
+int64 MessagesManager::get_inline_game_high_scores(const string &inline_message_id, UserId user_id,
+                                                   Promise<Unit> &&promise) {
+  if (!td_->auth_manager_->is_bot()) {
+    promise.set_error(Status::Error(3, "Method is available only for bots"));
+    return 0;
+  }
+
+  auto input_bot_inline_message_id = td_->inline_queries_manager_->get_input_bot_inline_message_id(inline_message_id);
+  if (input_bot_inline_message_id == nullptr) {
+    promise.set_error(Status::Error(400, "Wrong inline message identifier specified"));
+    return 0;
+  }
+
+  auto input_user = td_->contacts_manager_->get_input_user(user_id);
+  if (input_user == nullptr) {
+    promise.set_error(Status::Error(400, "Wrong user identifier specified"));
+    return 0;
+  }
+
+  int64 random_id = 0;
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 || game_high_scores_.find(random_id) != game_high_scores_.end());
+  game_high_scores_[random_id];  // reserve place for result
+
+  td_->create_handler<GetInlineGameHighScoresQuery>(std::move(promise))
+      ->send(std::move(input_bot_inline_message_id), std::move(input_user), random_id);
+  return random_id;
+}
+
+void MessagesManager::on_get_game_high_scores(int64 random_id,
+                                              tl_object_ptr<telegram_api::messages_highScores> &&high_scores) {
+  auto it = game_high_scores_.find(random_id);
+  CHECK(it != game_high_scores_.end());
+  auto &result = it->second;
+  CHECK(result == nullptr);
+
+  if (high_scores == nullptr) {
+    game_high_scores_.erase(it);
+    return;
+  }
+
+  td_->contacts_manager_->on_get_users(std::move(high_scores->users_));
+
+  result = make_tl_object<td_api::gameHighScores>();
+
+  for (auto &high_score : high_scores->scores_) {
+    int32 position = high_score->pos_;
+    if (position <= 0) {
+      LOG(ERROR) << "Receive wrong position = " << position;
+      continue;
+    }
+    UserId user_id(high_score->user_id_);
+    LOG_IF(ERROR, !td_->contacts_manager_->have_user(user_id)) << "Have no info about " << user_id;
+    int32 score = high_score->score_;
+    if (score < 0) {
+      LOG(ERROR) << "Receive wrong score = " << score;
+      continue;
+    }
+    result->scores_.push_back(make_tl_object<td_api::gameHighScore>(
+        position, td_->contacts_manager_->get_user_id_object(user_id, "gameHighScore"), score));
+  }
+}
+
+tl_object_ptr<td_api::gameHighScores> MessagesManager::get_game_high_scores_object(int64 random_id) {
+  auto it = game_high_scores_.find(random_id);
+  CHECK(it != game_high_scores_.end());
+  auto result = std::move(it->second);
+  game_high_scores_.erase(it);
+  return result;
+}
+
+unique_ptr<MessagesManager::MessageForwardInfo> MessagesManager::get_message_forward_info(
+    tl_object_ptr<telegram_api::messageFwdHeader> &&forward_header) {
+  if (forward_header == nullptr) {
+    return nullptr;
+  }
+
+  if (forward_header->date_ <= 0) {
+    LOG(ERROR) << "Wrong date in message forward header: " << oneline(to_string(forward_header));
+    return nullptr;
+  }
+
+  auto flags = forward_header->flags_;
+  UserId sender_user_id;
+  ChannelId channel_id;
+  MessageId message_id;
+  string author_signature;
+  DialogId from_dialog_id;
+  MessageId from_message_id;
+  if ((flags & MESSAGE_FORWARD_HEADER_FLAG_HAS_AUTHOR_ID) != 0) {
+    sender_user_id = UserId(forward_header->from_id_);
+    if (!sender_user_id.is_valid()) {
+      LOG(ERROR) << "Receive invalid sender id in message forward header: " << oneline(to_string(forward_header));
+      sender_user_id = UserId();
+    }
+  }
+  if ((flags & MESSAGE_FORWARD_HEADER_FLAG_HAS_CHANNEL_ID) != 0) {
+    channel_id = ChannelId(forward_header->channel_id_);
+    if (!channel_id.is_valid()) {
+      LOG(ERROR) << "Receive invalid channel id in message forward header: " << oneline(to_string(forward_header));
+    }
+  }
+  if ((flags & MESSAGE_FORWARD_HEADER_FLAG_HAS_MESSAGE_ID) != 0) {
+    message_id = MessageId(ServerMessageId(forward_header->channel_post_));
+    if (!message_id.is_valid()) {
+      LOG(ERROR) << "Receive " << message_id << " in message forward header: " << oneline(to_string(forward_header));
+      message_id = MessageId();
+    }
+  }
+  if ((flags & MESSAGE_FORWARD_HEADER_FLAG_HAS_AUTHOR_SIGNATURE) != 0) {
+    author_signature = std::move(forward_header->post_author_);
+  }
+  if ((flags & MESSAGE_FORWARD_HEADER_FLAG_HAS_SAVED_FROM) != 0) {
+    from_dialog_id = DialogId(forward_header->saved_from_peer_);
+    from_message_id = MessageId(ServerMessageId(forward_header->saved_from_msg_id_));
+    if (!from_dialog_id.is_valid() || !from_message_id.is_valid()) {
+      LOG(ERROR) << "Receive " << from_message_id << " in " << from_dialog_id
+                 << " in message forward header: " << oneline(to_string(forward_header));
+      from_dialog_id = DialogId();
+      from_message_id = MessageId();
+    }
+  }
+
+  DialogId dialog_id;
+  if (!channel_id.is_valid()) {
+    if (sender_user_id.is_valid()) {
+      if (message_id.is_valid()) {
+        LOG(ERROR) << "Receive non-empty message id in message forward header: " << oneline(to_string(forward_header));
+        message_id = MessageId();
+      }
+    } else {
+      LOG(ERROR) << "Receive wrong message forward header: " << oneline(to_string(forward_header));
+      return nullptr;
+    }
+  } else {
+    LOG_IF(ERROR, td_->contacts_manager_->have_min_channel(channel_id)) << "Receive forward from min channel";
+    dialog_id = DialogId(channel_id);
+    force_create_dialog(dialog_id, "message forward info");
+    if (sender_user_id.is_valid()) {
+      LOG(ERROR) << "Receive valid sender user id in message forward header: " << oneline(to_string(forward_header));
+      sender_user_id = UserId();
+    }
+  }
+  if (from_dialog_id.is_valid()) {
+    force_create_dialog(from_dialog_id, "message forward from info");
+  }
+
+  return make_unique<MessageForwardInfo>(sender_user_id, forward_header->date_, dialog_id, message_id, author_signature,
+                                         from_dialog_id, from_message_id);
+}
+
+tl_object_ptr<td_api::MessageForwardInfo> MessagesManager::get_message_forward_info_object(
+    const unique_ptr<MessageForwardInfo> &forward_info) const {
+  if (forward_info == nullptr) {
+    return nullptr;
+  }
+
+  if (forward_info->dialog_id.is_valid()) {
+    return make_tl_object<td_api::messageForwardedPost>(
+        forward_info->dialog_id.get(), forward_info->author_signature, forward_info->date,
+        forward_info->message_id.get(), forward_info->from_dialog_id.get(), forward_info->from_message_id.get());
+  }
+  return make_tl_object<td_api::messageForwardedFromUser>(
+      td_->contacts_manager_->get_user_id_object(forward_info->sender_user_id, "messageForwardedFromUser"),
+      forward_info->date, forward_info->from_dialog_id.get(), forward_info->from_message_id.get());
+}
+
+Result<unique_ptr<ReplyMarkup>> MessagesManager::get_dialog_reply_markup(
+    DialogId dialog_id, tl_object_ptr<td_api::ReplyMarkup> &&reply_markup_ptr) const {
+  if (reply_markup_ptr == nullptr) {
+    return nullptr;
+  }
+
+  auto dialog_type = dialog_id.get_type();
+  bool is_broadcast = is_broadcast_channel(dialog_id);
+
+  bool only_inline_keyboard = is_broadcast;
+  bool request_buttons_allowed = dialog_type == DialogType::User;
+  bool switch_inline_current_chat_buttons_allowed = !is_broadcast;
+
+  TRY_RESULT(reply_markup,
+             get_reply_markup(std::move(reply_markup_ptr), td_->auth_manager_->is_bot(), only_inline_keyboard,
+                              request_buttons_allowed, switch_inline_current_chat_buttons_allowed));
+  if (reply_markup == nullptr) {
+    return nullptr;
+  }
+
+  switch (dialog_type) {
+    case DialogType::User:
+      if (reply_markup->type != ReplyMarkup::Type::InlineKeyboard) {
+        reply_markup->is_personal = false;
+      }
+      break;
+    case DialogType::Channel:
+    case DialogType::Chat:
+    case DialogType::SecretChat:
+    case DialogType::None:
+      // nothing special
+      break;
+    default:
+      UNREACHABLE();
+  }
+
+  return std::move(reply_markup);
+}
+
+class MessagesManager::ForwardMessagesLogEvent {
+ public:
+  DialogId to_dialog_id;
+  DialogId from_dialog_id;
+  vector<MessageId> message_ids;
+  vector<Message *> messages_in;
+  vector<unique_ptr<Message>> messages_out;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(to_dialog_id, storer);
+    td::store(from_dialog_id, storer);
+    td::store(message_ids, storer);
+
+    td::store(narrow_cast<int32>(messages_in.size()), storer);
+    for (auto m : messages_in) {
+      td::store(*m, storer);
+    }
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(to_dialog_id, parser);
+    td::parse(from_dialog_id, parser);
+    td::parse(message_ids, parser);
+
+    CHECK(messages_out.empty());
+    int32 size = parser.fetch_int();
+    messages_out.resize(size);
+    for (auto &m_out : messages_out) {
+      m_out = make_unique<Message>();
+      td::parse(*m_out, parser);
+    }
+  }
+};
+
+void MessagesManager::do_forward_messages(DialogId to_dialog_id, DialogId from_dialog_id,
+                                          const vector<Message *> &messages, const vector<MessageId> &message_ids,
+                                          int64 logevent_id) {
+  CHECK(messages.size() == message_ids.size());
+  if (messages.empty()) {
+    return;
+  }
+
+  if (logevent_id == 0 && G()->parameters().use_message_db) {
+    auto logevent = ForwardMessagesLogEvent{to_dialog_id, from_dialog_id, message_ids, messages, Auto()};
+    auto storer = LogEventStorerImpl<ForwardMessagesLogEvent>(logevent);
+    logevent_id = BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::ForwardMessages, storer);
+  }
+
+  Promise<> promise;
+  if (logevent_id != 0) {
+    promise = PromiseCreator::lambda([logevent_id](Result<Unit> result) mutable {
+      if (!G()->close_flag()) {
+        BinlogHelper::erase(G()->td_db()->get_binlog(), logevent_id);
+      }
+    });
+  }
+
+  int32 flags = 0;
+  if (messages[0]->disable_notification) {
+    flags |= SEND_MESSAGE_FLAG_DISABLE_NOTIFICATION;
+  }
+  if (messages[0]->from_background) {
+    flags |= SEND_MESSAGE_FLAG_FROM_BACKGROUND;
+  }
+  if (messages[0]->media_album_id != 0) {
+    flags |= SEND_MESSAGE_FLAG_GROUP_MEDIA;
+  }
+  if (messages[0]->in_game_share) {
+    flags |= SEND_MESSAGE_FLAG_WITH_MY_SCORE;
+  }
+
+  vector<int64> random_ids =
+      transform(messages, [this, to_dialog_id](const Message *m) { return begin_send_message(to_dialog_id, m); });
+  send_closure(td_->create_net_actor<ForwardMessagesActor>(std::move(promise)), &ForwardMessagesActor::send, flags,
+               to_dialog_id, from_dialog_id, message_ids, std::move(random_ids),
+               get_sequence_dispatcher_id(to_dialog_id, -1));
+}
+
+Result<MessageId> MessagesManager::forward_message(DialogId to_dialog_id, DialogId from_dialog_id, MessageId message_id,
+                                                   bool disable_notification, bool from_background,
+                                                   bool in_game_share) {
+  TRY_RESULT(result, forward_messages(to_dialog_id, from_dialog_id, {message_id}, disable_notification, from_background,
+                                      in_game_share, false));
+  CHECK(result.size() == 1);
+  auto sent_message_id = result[0];
+  if (sent_message_id == MessageId()) {
+    return Status::Error(11, "Message can't be forwarded");
+  }
+  return sent_message_id;
+}
+
+Result<vector<MessageId>> MessagesManager::forward_messages(DialogId to_dialog_id, DialogId from_dialog_id,
+                                                            vector<MessageId> message_ids, bool disable_notification,
+                                                            bool from_background, bool in_game_share, bool as_album) {
+  if (message_ids.size() > 100) {  // TODO replace with const from config or implement mass-forward
+    return Status::Error(4, "Too much messages to forward");
+  }
+  if (message_ids.empty()) {
+    return Status::Error(4, "There is no messages to forward");
+  }
+
+  Dialog *from_dialog = get_dialog_force(from_dialog_id);
+  if (from_dialog == nullptr) {
+    return Status::Error(5, "Chat to forward messages from not found");
+  }
+  if (!have_input_peer(from_dialog_id, AccessRights::Read)) {
+    return Status::Error(5, "Can't access the chat to forward messages from");
+  }
+  if (from_dialog_id.get_type() == DialogType::SecretChat) {
+    return Status::Error(7, "Can't forward messages from secret chats");
+  }
+
+  Dialog *to_dialog = get_dialog_force(to_dialog_id);
+  if (to_dialog == nullptr) {
+    return Status::Error(5, "Chat to forward messages to not found");
+  }
+
+  TRY_STATUS(can_send_message(to_dialog_id));
+
+  for (auto message_id : message_ids) {
+    if (!message_id.is_valid()) {
+      return Status::Error(5, "Invalid message identifier");
+    }
+  }
+
+  int64 media_album_id = 0;
+  if (as_album && message_ids.size() > 1 && message_ids.size() <= MAX_GROUPED_MESSAGES) {
+    do {
+      media_album_id = Random::secure_int64();
+    } while (media_album_id >= 0 || pending_message_group_sends_.count(media_album_id) != 0);
+  }
+
+  bool to_secret = to_dialog_id.get_type() == DialogType::SecretChat;
+
+  vector<MessageId> result(message_ids.size());
+  vector<Message *> forwarded_messages;
+  vector<MessageId> forwarded_message_ids;
+  vector<unique_ptr<MessageContent>> unforwarded_message_contents(message_ids.size());
+  vector<bool> unforwarded_message_disable_web_page_previews(message_ids.size());
+  auto my_id = td_->contacts_manager_->get_my_id("forward_message");
+  bool need_update_dialog_pos = false;
+  for (size_t i = 0; i < message_ids.size(); i++) {
+    MessageId message_id = get_persistent_message_id(from_dialog, message_ids[i]);
+
+    const Message *forwarded_message = get_message_force(from_dialog, message_id);
+    if (forwarded_message == nullptr) {
+      LOG(INFO) << "Can't find " << message_id << " to forward";
+      continue;
+    }
+
+    if (!can_forward_message(from_dialog_id, forwarded_message)) {
+      LOG(INFO) << "Can't forward " << message_id;
+      continue;
+    }
+
+    unique_ptr<MessageContent> content = dup_message_content(to_dialog_id, forwarded_message->content.get(), true);
+    if (content == nullptr) {
+      LOG(INFO) << "Can't forward " << message_id;
+      continue;
+    }
+
+    auto can_send_status = can_send_message_content(to_dialog_id, content.get(), true);
+    if (can_send_status.is_error()) {
+      LOG(INFO) << "Can't forward " << message_id << ": " << can_send_status.message();
+      continue;
+    }
+
+    if (!message_id.is_server() || to_secret) {
+      unforwarded_message_contents[i] = std::move(content);
+      unforwarded_message_disable_web_page_previews[i] = forwarded_message->disable_web_page_preview;
+      continue;
+    }
+
+    auto content_id = content->get_id();
+    if (media_album_id != 0 && !is_allowed_media_group_content(content_id)) {
+      media_album_id = 0;
+      for (auto m : forwarded_messages) {
+        m->media_album_id = 0;
+      }
+    }
+
+    bool is_game = content_id == MessageGame::ID;
+    unique_ptr<MessageForwardInfo> forward_info;
+    if (!is_game && content_id != MessageAudio::ID) {
+      DialogId saved_from_dialog_id;
+      MessageId saved_from_message_id;
+      if (to_dialog_id == DialogId(my_id)) {
+        saved_from_dialog_id = from_dialog_id;
+        saved_from_message_id = message_id;
+      }
+
+      if (forwarded_message->forward_info != nullptr) {
+        forward_info = make_unique<MessageForwardInfo>(*forwarded_message->forward_info);
+        forward_info->from_dialog_id = saved_from_dialog_id;
+        forward_info->from_message_id = saved_from_message_id;
+      } else {
+        if (from_dialog_id != DialogId(my_id)) {
+          if (!forwarded_message->is_channel_post) {
+            forward_info =
+                make_unique<MessageForwardInfo>(forwarded_message->sender_user_id, forwarded_message->date, DialogId(),
+                                                MessageId(), "", saved_from_dialog_id, saved_from_message_id);
+          } else {
+            CHECK(from_dialog_id.get_type() == DialogType::Channel);
+            MessageId forwarded_message_id = forwarded_message->message_id;
+            auto author_signature = forwarded_message->sender_user_id.is_valid()
+                                        ? td_->contacts_manager_->get_user_title(forwarded_message->sender_user_id)
+                                        : forwarded_message->author_signature;
+            forward_info = make_unique<MessageForwardInfo>(UserId(), forwarded_message->date, from_dialog_id,
+                                                           forwarded_message_id, std::move(author_signature),
+                                                           saved_from_dialog_id, saved_from_message_id);
+          }
+        }
+      }
+    }
+
+    Message *m = get_message_to_send(to_dialog, MessageId(), disable_notification, from_background, std::move(content),
+                                     &need_update_dialog_pos, std::move(forward_info));
+    m->debug_forward_from = from_dialog_id;
+    m->via_bot_user_id = forwarded_message->via_bot_user_id;
+    m->media_album_id = media_album_id;
+    m->in_game_share = in_game_share;
+    if (forwarded_message->views > 0) {
+      m->views = forwarded_message->views;
+    }
+
+    if (is_game) {
+      if (m->via_bot_user_id == my_id) {
+        m->via_bot_user_id = UserId();
+      } else if (m->via_bot_user_id == UserId()) {
+        m->via_bot_user_id = forwarded_message->sender_user_id;
+      }
+    }
+
+    result[i] = m->message_id;
+    forwarded_messages.push_back(m);
+    forwarded_message_ids.push_back(message_id);
+
+    send_update_new_message(to_dialog, m, true);
+  }
+
+  if (!forwarded_messages.empty()) {
+    do_forward_messages(to_dialog_id, from_dialog_id, forwarded_messages, forwarded_message_ids, 0);
+  }
+
+  for (size_t i = 0; i < unforwarded_message_contents.size(); i++) {
+    if (unforwarded_message_contents[i] != nullptr) {
+      Message *m = get_message_to_send(to_dialog, MessageId(), disable_notification, from_background,
+                                       std::move(unforwarded_message_contents[i]), &need_update_dialog_pos);
+      m->disable_web_page_preview = unforwarded_message_disable_web_page_previews[i];
+      if (to_secret) {
+        m->media_album_id = media_album_id;
+      }
+
+      save_send_message_logevent(to_dialog_id, m);
+      do_send_message(to_dialog_id, m);
+      result[i] = m->message_id;
+
+      send_update_new_message(to_dialog, m, true);
+    }
+  }
+
+  if (need_update_dialog_pos) {
+    send_update_chat_last_message(to_dialog, "forward_messages");
+  }
+
+  return result;
+}
+
+Result<MessageId> MessagesManager::send_dialog_set_ttl_message(DialogId dialog_id, int32 ttl) {
+  if (dialog_id.get_type() != DialogType::SecretChat) {
+    return Status::Error(5, "Can't set chat ttl in non-secret chat");
+  }
+
+  if (ttl < 0) {
+    return Status::Error(5, "Message ttl can't be negative");
+  }
+
+  LOG(INFO) << "Begin to set ttl in " << dialog_id << " to " << ttl;
+
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return Status::Error(5, "Chat not found");
+  }
+
+  TRY_STATUS(can_send_message(dialog_id));
+  bool need_update_dialog_pos = false;
+  Message *m =
+      get_message_to_send(d, MessageId(), false, false, make_unique<MessageChatSetTtl>(ttl), &need_update_dialog_pos);
+
+  send_update_new_message(d, m, true);
+  if (need_update_dialog_pos) {
+    send_update_chat_last_message(d, "send_dialog_set_ttl_message");
+  }
+
+  int64 random_id = begin_send_message(dialog_id, m);
+
+  send_closure(td_->secret_chats_manager_, &SecretChatsManager::send_set_ttl_message, dialog_id.get_secret_chat_id(),
+               ttl, random_id, Promise<>());  // TODO Promise
+
+  return m->message_id;
+}
+
+Status MessagesManager::send_screenshot_taken_notification_message(DialogId dialog_id) {
+  auto dialog_type = dialog_id.get_type();
+  if (dialog_type != DialogType::User && dialog_type != DialogType::SecretChat) {
+    return Status::Error(5, "Notification about taken screenshot can be sent only in private and secret chats");
+  }
+
+  LOG(INFO) << "Begin to send notification about taken screenshot in " << dialog_id;
+
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    return Status::Error(5, "Chat not found");
+  }
+
+  TRY_STATUS(can_send_message(dialog_id));
+
+  if (dialog_type == DialogType::User) {
+    bool need_update_dialog_pos = false;
+    const Message *m = get_message_to_send(d, MessageId(), false, false, make_unique<MessageScreenshotTaken>(),
+                                           &need_update_dialog_pos);
+
+    do_send_screenshot_taken_notification_message(dialog_id, m, 0);
+
+    send_update_new_message(d, m, true);
+    if (need_update_dialog_pos) {
+      send_update_chat_last_message(d, "send_screenshot_taken_notification_message");
+    }
+  } else {
+    send_closure(td_->secret_chats_manager_, &SecretChatsManager::notify_screenshot_taken,
+                 dialog_id.get_secret_chat_id(),
+                 Promise<>());  // TODO Promise
+  }
+
+  return Status::OK();
+}
+
+class MessagesManager::SendScreenshotTakenNotificationMessageLogEvent {
+ public:
+  DialogId dialog_id;
+  const Message *m_in = nullptr;
+  unique_ptr<Message> m_out;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(dialog_id, storer);
+    td::store(*m_in, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(dialog_id, parser);
+    CHECK(m_out == nullptr);
+    m_out = make_unique<Message>();
+    td::parse(*m_out, parser);
+  }
+};
+
+uint64 MessagesManager::save_send_screenshot_taken_notification_message_logevent(DialogId dialog_id, const Message *m) {
+  if (!G()->parameters().use_message_db) {
+    return 0;
+  }
+
+  CHECK(m != nullptr);
+  LOG(INFO) << "Save " << FullMessageId(dialog_id, m->message_id) << " to binlog";
+  SendScreenshotTakenNotificationMessageLogEvent logevent;
+  logevent.dialog_id = dialog_id;
+  logevent.m_in = m;
+  auto storer = LogEventStorerImpl<SendScreenshotTakenNotificationMessageLogEvent>(logevent);
+  return BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::SendScreenshotTakenNotificationMessage,
+                           storer);
+}
+
+void MessagesManager::do_send_screenshot_taken_notification_message(DialogId dialog_id, const Message *m,
+                                                                    uint64 logevent_id) {
+  LOG(INFO) << "Do send screenshot taken notification " << FullMessageId(dialog_id, m->message_id);
+  CHECK(dialog_id.get_type() == DialogType::User);
+
+  if (logevent_id == 0) {
+    logevent_id = save_send_screenshot_taken_notification_message_logevent(dialog_id, m);
+  }
+
+  Promise<> promise;
+  if (logevent_id != 0) {
+    promise = PromiseCreator::lambda([logevent_id](Result<Unit> result) mutable {
+      LOG(INFO) << "Erase logevent_id " << logevent_id;
+      if (!G()->close_flag()) {
+        BinlogHelper::erase(G()->td_db()->get_binlog(), logevent_id);
+      }
+    });
+  }
+
+  int64 random_id = begin_send_message(dialog_id, m);
+  td_->create_handler<SendScreenshotNotificationQuery>(std::move(promise))->send(dialog_id, random_id);
+}
+
+bool MessagesManager::on_update_message_id(int64 random_id, MessageId new_message_id, const string &source) {
+  if (!new_message_id.is_valid()) {
+    LOG(ERROR) << "Receive " << new_message_id << " in update message id with random_id " << random_id << " from "
+               << source;
+    auto it = debug_being_sent_messages_.find(random_id);
+    if (it == debug_being_sent_messages_.end()) {
+      LOG(ERROR) << "Message with random_id " << random_id << " was not sent";
+      return false;
+    }
+    auto dialog_id = it->second;
+    if (!dialog_id.is_valid()) {
+      LOG(ERROR) << "Sent message is in invalid " << dialog_id;
+      return false;
+    }
+    if (!have_dialog(dialog_id)) {
+      LOG(ERROR) << "Sent message is in not found " << dialog_id;
+      return false;
+    }
+    LOG(ERROR) << "Receive " << new_message_id << " in update message id with random_id " << random_id << " in "
+               << dialog_id;
+    return false;
+  }
+
+  auto it = being_sent_messages_.find(random_id);
+  if (it == being_sent_messages_.end()) {
+    // update about new message sent from other device or service message
+    LOG(INFO) << "Receive not send outgoing " << new_message_id << " with random_id = " << random_id;
+    return true;
+  }
+
+  auto dialog_id = it->second.get_dialog_id();
+  auto old_message_id = it->second.get_message_id();
+
+  being_sent_messages_.erase(it);
+
+  update_message_ids_[FullMessageId(dialog_id, new_message_id)] = old_message_id;
+  return true;
+}
+
+bool MessagesManager::on_get_dialog_error(DialogId dialog_id, const Status &status, const string &source) {
+  if (status.message() == CSlice("SESSION_REVOKED") || status.message() == CSlice("USER_DEACTIVATED")) {
+    // authorization is lost
+    return true;
+  }
+  if (status.code() == 420 || status.code() == 429) {
+    // flood wait
+    return true;
+  }
+  if (status.message() == CSlice("BOT_METHOD_INVALID")) {
+    LOG(ERROR) << "Receive BOT_METHOD_INVALID from " << source;
+    return true;
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+    case DialogType::SecretChat:
+      // to be implemented if necessary
+      break;
+    case DialogType::Channel:
+      return td_->contacts_manager_->on_get_channel_error(dialog_id.get_channel_id(), status, source);
+    case DialogType::None:
+      // to be implemented if necessary
+      break;
+    default:
+      UNREACHABLE();
+  }
+  return false;
+}
+
+void MessagesManager::on_dialog_updated(DialogId dialog_id, const char *source) {
+  if (G()->parameters().use_message_db) {
+    LOG(INFO) << "Update " << dialog_id << " from " << source;
+    pending_updated_dialog_timeout_.add_timeout_in(dialog_id.get(), MAX_SAVE_DIALOG_DELAY);
+  }
+}
+
+void MessagesManager::send_update_new_message(Dialog *d, const Message *m, bool force) {
+  CHECK(d != nullptr);
+  CHECK(m != nullptr);
+
+  DialogId my_dialog_id(td_->contacts_manager_->get_my_id("send_update_new_message"));
+  bool disable_notification =
+      m->disable_notification || m->is_outgoing || d->dialog_id == my_dialog_id || td_->auth_manager_->is_bot();
+  if (m->message_id.get() <= d->last_read_inbox_message_id.get()) {
+    LOG(INFO) << "Disable notification for read " << m->message_id << " in " << d->dialog_id;
+    disable_notification = true;
+  }
+  if (!disable_notification && d->dialog_id.get_type() == DialogType::Channel) {
+    if (!td_->contacts_manager_->get_channel_status(d->dialog_id.get_channel_id()).is_member()) {
+      disable_notification = true;
+    }
+  }
+  bool have_settings = true;
+  DialogId settings_dialog_id;
+  if (!disable_notification) {
+    Dialog *settings_dialog;
+    if (!m->contains_mention || !m->sender_user_id.is_valid()) {
+      // use notification settings from the dialog
+      settings_dialog_id = d->dialog_id;
+      settings_dialog = d;
+    } else {
+      // have a mention, so use notification settings from the dialog with the sender
+      settings_dialog_id = DialogId(m->sender_user_id);
+      settings_dialog = get_dialog_force(settings_dialog_id);
+    }
+
+    auto notification_settings = get_dialog_notification_settings(settings_dialog, settings_dialog_id);
+    if (notification_settings == nullptr ||  // unknown megagroup without mention
+        notification_settings->mute_until > G()->unix_time()) {
+      disable_notification = true;
+    }
+    if (settings_dialog == nullptr || !settings_dialog->notification_settings.is_synchronized) {
+      have_settings = false;
+    }
+  }
+
+  if (!force && (!have_settings || !d->pending_update_new_messages.empty())) {
+    LOG(INFO) << "Delay update new message for " << m->message_id << " in " << d->dialog_id;
+    if (d->pending_update_new_messages.empty()) {
+      create_actor<SleepActor>(
+          "FlushPendingUpdateNewMessagesSleepActor", 5.0,
+          PromiseCreator::lambda([actor_id = actor_id(this), dialog_id = d->dialog_id](Result<Unit> result) {
+            send_closure(actor_id, &MessagesManager::flush_pending_update_new_messages, dialog_id);
+          }))
+          .release();
+    }
+    d->pending_update_new_messages.push_back(m->message_id);
+    auto promise = PromiseCreator::lambda([actor_id = actor_id(this), dialog_id = d->dialog_id](Result<Unit> result) {
+      send_closure(actor_id, &MessagesManager::flush_pending_update_new_messages, dialog_id);
+    });
+    send_get_dialog_query(settings_dialog_id, std::move(promise));  // TODO use GetNotifySettingsQuery when possible
+    return;
+  }
+
+  LOG_IF(WARNING, !have_settings) << "Have no notification settings for " << settings_dialog_id;
+  send_closure(G()->td(), &Td::send_update,
+               make_tl_object<td_api::updateNewMessage>(get_message_object(d->dialog_id, m), disable_notification,
+                                                        m->contains_mention));
+}
+
+void MessagesManager::flush_pending_update_new_messages(DialogId dialog_id) {
+  auto d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+  if (d->pending_update_new_messages.empty()) {
+    return;
+  }
+  auto message_ids = std::move(d->pending_update_new_messages);
+  reset_to_empty(d->pending_update_new_messages);
+  for (auto message_id : message_ids) {
+    auto m = get_message(d, message_id);
+    if (m != nullptr) {
+      send_update_new_message(d, m, true);
+    }
+  }
+}
+
+void MessagesManager::send_update_message_send_succeeded(Dialog *d, MessageId old_message_id, const Message *m) const {
+  CHECK(m != nullptr);
+  d->yet_unsent_message_id_to_persistent_message_id.emplace(old_message_id, m->message_id);
+  send_closure(
+      G()->td(), &Td::send_update,
+      make_tl_object<td_api::updateMessageSendSucceeded>(get_message_object(d->dialog_id, m), old_message_id.get()));
+}
+
+void MessagesManager::send_update_message_content(DialogId dialog_id, MessageId message_id,
+                                                  const MessageContent *content, int32 message_date,
+                                                  bool is_content_secret, const char *source) const {
+  LOG(INFO) << "Send updateMessageContent for " << message_id << " in " << dialog_id << " from " << source;
+  CHECK(have_dialog(dialog_id)) << "Send updateMessageContent in unknown " << dialog_id << " from " << source
+                                << " with load count " << loaded_dialogs_.count(dialog_id);
+  send_closure(
+      G()->td(), &Td::send_update,
+      make_tl_object<td_api::updateMessageContent>(
+          dialog_id.get(), message_id.get(), get_message_content_object(content, message_date, is_content_secret)));
+}
+
+void MessagesManager::send_update_message_edited(FullMessageId full_message_id) {
+  return send_update_message_edited(full_message_id.get_dialog_id(), get_message(full_message_id));
+}
+
+void MessagesManager::send_update_message_edited(DialogId dialog_id, const Message *m) {
+  CHECK(m != nullptr);
+  cancel_user_dialog_action(dialog_id, m);
+  send_closure(G()->td(), &Td::send_update,
+               make_tl_object<td_api::updateMessageEdited>(dialog_id.get(), m->message_id.get(), m->edit_date,
+                                                           get_reply_markup_object(m->reply_markup)));
+}
+
+void MessagesManager::send_update_delete_messages(DialogId dialog_id, vector<int64> &&message_ids, bool is_permanent,
+                                                  bool from_cache) const {
+  if (!message_ids.empty()) {
+    CHECK(have_dialog(dialog_id)) << "Wrong " << dialog_id << " in send_update_delete_messages";
+    send_closure(G()->td(), &Td::send_update,
+                 make_tl_object<td_api::updateDeleteMessages>(dialog_id.get(), std::move(message_ids), is_permanent,
+                                                              from_cache));
+  }
+}
+
+void MessagesManager::send_update_chat(Dialog *d) {
+  CHECK(d != nullptr);
+  CHECK(d->messages == nullptr);
+  send_closure(G()->td(), &Td::send_update, make_tl_object<td_api::updateNewChat>(get_chat_object(d)));
+}
+
+void MessagesManager::send_update_chat_draft_message(const Dialog *d) {
+  CHECK(d != nullptr);
+  CHECK(d == get_dialog(d->dialog_id)) << "Wrong " << d->dialog_id << " in send_update_chat_draft_message";
+  on_dialog_updated(d->dialog_id, "send_update_chat_draft_message");
+  send_closure(G()->td(), &Td::send_update,
+               make_tl_object<td_api::updateChatDraftMessage>(
+                   d->dialog_id.get(), get_draft_message_object(d->draft_message),
+                   DialogDate(d->order, d->dialog_id) <= last_dialog_date_ ? d->order : 0));
+}
+
+void MessagesManager::send_update_chat_last_message(Dialog *d, const char *source) {
+  update_dialog_pos(d, false, source, false);
+  send_update_chat_last_message_impl(d, source);
+}
+
+void MessagesManager::send_update_chat_last_message_impl(const Dialog *d, const char *source) const {
+  CHECK(d != nullptr);
+  CHECK(d == get_dialog(d->dialog_id)) << "Wrong " << d->dialog_id << " in send_update_chat_last_message from "
+                                       << source;
+  LOG(INFO) << "Send updateChatLastMessage in " << d->dialog_id << " to " << d->last_message_id << " from " << source;
+  auto update = make_tl_object<td_api::updateChatLastMessage>(
+      d->dialog_id.get(), get_message_object(d->dialog_id, get_message(d, d->last_message_id)),
+      DialogDate(d->order, d->dialog_id) <= last_dialog_date_ ? d->order : 0);
+  send_closure(G()->td(), &Td::send_update, std::move(update));
+}
+
+void MessagesManager::send_update_unread_message_count(DialogId dialog_id, bool force, const char *source) {
+  if (!td_->auth_manager_->is_bot() && G()->parameters().use_message_db) {
+    CHECK(is_unread_count_inited_);
+    if (unread_message_total_count_ < 0 || unread_message_muted_count_ < 0 ||
+        unread_message_muted_count_ > unread_message_total_count_) {
+      LOG(ERROR) << "Unread messafe count became invalid: " << unread_message_total_count_ << '/'
+                 << unread_message_total_count_ - unread_message_muted_count_ << " from " << source << " and "
+                 << dialog_id;
+      if (unread_message_total_count_ < 0) {
+        unread_message_total_count_ = 0;
+      }
+      if (unread_message_muted_count_ < 0) {
+        unread_message_muted_count_ = 0;
+      }
+      if (unread_message_muted_count_ > unread_message_total_count_) {
+        unread_message_muted_count_ = unread_message_total_count_;
+      }
+    }
+    G()->td_db()->get_binlog_pmc()->set("unread_message_count",
+                                        PSTRING() << unread_message_total_count_ << ' ' << unread_message_muted_count_);
+    int32 unread_unmuted_count = unread_message_total_count_ - unread_message_muted_count_;
+    if (!force && running_get_difference_) {
+      LOG(INFO) << "Postpone updateUnreadMessageCount to " << unread_message_total_count_ << '/' << unread_unmuted_count
+                << " from " << source << " and " << dialog_id;
+      have_postponed_unread_message_count_update_ = true;
+    } else {
+      have_postponed_unread_message_count_update_ = false;
+      LOG(INFO) << "Send updateUnreadMessageCount to " << unread_message_total_count_ << '/' << unread_unmuted_count
+                << " from " << source << " and " << dialog_id;
+      send_closure(G()->td(), &Td::send_update,
+                   make_tl_object<td_api::updateUnreadMessageCount>(unread_message_total_count_, unread_unmuted_count));
+    }
+  }
+}
+
+void MessagesManager::send_update_chat_read_inbox(const Dialog *d, bool force, const char *source) {
+  CHECK(d != nullptr);
+  if (!td_->auth_manager_->is_bot()) {
+    CHECK(d == get_dialog(d->dialog_id)) << "Wrong " << d->dialog_id << " in send_update_chat_read_inbox from "
+                                         << source;
+    on_dialog_updated(d->dialog_id, source);
+    if (!force && (running_get_difference_ || running_get_channel_difference(d->dialog_id))) {
+      LOG(INFO) << "Postpone updateChatReadInbox in " << d->dialog_id << "(" << get_dialog_title(d->dialog_id)
+                << ") to " << d->server_unread_count << " + " << d->local_unread_count << " from " << source;
+      postponed_chat_read_inbox_updates_.insert(d->dialog_id);
+    } else {
+      postponed_chat_read_inbox_updates_.erase(d->dialog_id);
+      LOG(INFO) << "Send updateChatReadInbox in " << d->dialog_id << "(" << get_dialog_title(d->dialog_id) << ") to "
+                << d->server_unread_count << " + " << d->local_unread_count << " from " << source;
+      send_closure(G()->td(), &Td::send_update,
+                   make_tl_object<td_api::updateChatReadInbox>(d->dialog_id.get(), d->last_read_inbox_message_id.get(),
+                                                               d->server_unread_count + d->local_unread_count));
+    }
+  }
+}
+
+void MessagesManager::send_update_chat_read_outbox(const Dialog *d) {
+  CHECK(d != nullptr);
+  if (!td_->auth_manager_->is_bot()) {
+    CHECK(d == get_dialog(d->dialog_id)) << "Wrong " << d->dialog_id << " in send_update_chat_read_outbox";
+    on_dialog_updated(d->dialog_id, "send_update_chat_read_outbox");
+    send_closure(
+        G()->td(), &Td::send_update,
+        make_tl_object<td_api::updateChatReadOutbox>(d->dialog_id.get(), d->last_read_outbox_message_id.get()));
+  }
+}
+
+void MessagesManager::send_update_chat_unread_mention_count(const Dialog *d) {
+  CHECK(d != nullptr);
+  if (!td_->auth_manager_->is_bot()) {
+    CHECK(d == get_dialog(d->dialog_id)) << "Wrong " << d->dialog_id << " in send_update_chat_unread_mention_count";
+    LOG(INFO) << "Update unread mention message count in " << d->dialog_id << " to " << d->unread_mention_count;
+    on_dialog_updated(d->dialog_id, "send_update_chat_unread_mention_count");
+    send_closure(G()->td(), &Td::send_update,
+                 make_tl_object<td_api::updateChatUnreadMentionCount>(d->dialog_id.get(), d->unread_mention_count));
+  }
+}
+
+void MessagesManager::on_send_message_get_quick_ack(int64 random_id) {
+  auto it = being_sent_messages_.find(random_id);
+  if (it == being_sent_messages_.end()) {
+    LOG(ERROR) << "Receive quick ack about unknown message with random_id = " << random_id;
+    return;
+  }
+
+  auto dialog_id = it->second.get_dialog_id();
+  auto message_id = it->second.get_message_id();
+
+  send_closure(G()->td(), &Td::send_update,
+               make_tl_object<td_api::updateMessageSendAcknowledged>(dialog_id.get(), message_id.get()));
+}
+
+void MessagesManager::check_send_message_result(int64 random_id, DialogId dialog_id,
+                                                const telegram_api::Updates *updates_ptr, const char *source) {
+  CHECK(updates_ptr != nullptr);
+  CHECK(source != nullptr);
+  auto sent_messages = td_->updates_manager_->get_new_messages(updates_ptr);
+  auto sent_messages_random_ids = td_->updates_manager_->get_sent_messages_random_ids(updates_ptr);
+  if (sent_messages.size() != 1u || sent_messages_random_ids.size() != 1u ||
+      *sent_messages_random_ids.begin() != random_id || get_message_dialog_id(*sent_messages[0]) != dialog_id) {
+    LOG(ERROR) << "Receive wrong result for sending message with random_id " << random_id << " from " << source
+               << " to " << dialog_id << ": " << oneline(to_string(*updates_ptr));
+    if (dialog_id.get_type() == DialogType::Channel) {
+      Dialog *d = get_dialog(dialog_id);
+      CHECK(d != nullptr);
+      get_channel_difference(dialog_id, d->pts, true, "check_send_message_result");
+    } else {
+      td_->updates_manager_->schedule_get_difference("check_send_message_result");
+    }
+  }
+}
+
+FullMessageId MessagesManager::on_send_message_success(int64 random_id, MessageId new_message_id, int32 date,
+                                                       FileId new_file_id, const char *source) {
+  CHECK(source != nullptr);
+  // do not try to run getDifference from this function
+  if (DROP_UPDATES) {
+    return {};
+  }
+  if (!new_message_id.is_valid()) {
+    LOG(ERROR) << "Receive " << new_message_id << " as sent message from " << source;
+    on_send_message_fail(random_id,
+                         Status::Error(500, "Internal server error: receive invalid message id as sent message id"));
+    return {};
+  }
+  if (new_message_id.is_yet_unsent()) {
+    LOG(ERROR) << "Receive " << new_message_id << " as sent message from " << source;
+    on_send_message_fail(random_id,
+                         Status::Error(500, "Internal server error: receive yet unsent message as sent message"));
+    return {};
+  }
+
+  auto it = being_sent_messages_.find(random_id);
+  if (it == being_sent_messages_.end()) {
+    LOG(ERROR) << "Result from sendMessage for " << new_message_id << " with random_id " << random_id << " sent at "
+               << date << " comes from " << source << " after updateNewMessageId, but was not discarded by pts. "
+               << td_->updates_manager_->get_state();
+    if (debug_being_sent_messages_.count(random_id) == 0) {
+      LOG(ERROR) << "Message with random_id " << random_id << " was mot sent";
+      return {};
+    }
+    auto dialog_id = debug_being_sent_messages_[random_id];
+    if (!dialog_id.is_valid()) {
+      LOG(ERROR) << "Sent message is in invalid " << dialog_id;
+      return {};
+    }
+    auto d = get_dialog(dialog_id);
+    if (d == nullptr) {
+      LOG(ERROR) << "Sent message is in not found " << dialog_id;
+      return {};
+    }
+    dump_debug_message_op(d, 7);
+    auto m = get_message_force(d, new_message_id);
+    if (m == nullptr) {
+      LOG(ERROR) << new_message_id << " in " << dialog_id << " not found";
+      return {};
+    }
+    LOG(ERROR) << "Result from sent " << (m->is_outgoing ? "outgoing" : "incoming")
+               << (m->forward_info == nullptr ? " not" : "") << " forwarded " << new_message_id
+               << " with content of the type " << m->content->get_id() << " in " << dialog_id
+               << " comes after updateNewMessageId, current last new is " << d->last_new_message_id << ", last is "
+               << d->last_message_id << ". " << td_->updates_manager_->get_state();
+    return {};
+  }
+
+  auto dialog_id = it->second.get_dialog_id();
+  auto old_message_id = it->second.get_message_id();
+
+  being_sent_messages_.erase(it);
+
+  Dialog *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+
+  bool need_update_dialog_pos = false;
+  unique_ptr<Message> sent_message = delete_message(d, old_message_id, false, &need_update_dialog_pos, source);
+  if (sent_message == nullptr) {
+    // message has already been deleted by the user or sent to inaccessible channel
+    // don't need to send update to the user, because the message has already been deleted
+    LOG(INFO) << "Delete already deleted sent " << new_message_id << " from server";
+    delete_messages_from_server(dialog_id, {new_message_id}, true, 0, Auto());
+    return {};
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    // LOG(ERROR) << "Found " << old_message_id << " in inaccessible " << dialog_id;
+    // dump_debug_message_op(d, 5);
+  }
+
+  // imitation of update_message(d, sent_message, std::move(new_message), true, &need_update_dialog_pos);
+  if (date <= 0) {
+    LOG(ERROR) << "Receive " << new_message_id << " in " << dialog_id << " with wrong date " << date;
+  } else {
+    CHECK(sent_message->date > 0);
+    sent_message->date = date;
+    CHECK(d->last_message_id != old_message_id);
+  }
+
+  // reply_to message may be already deleted
+  // but can't use get_message for check, because the message can be already unloaded from the memory
+  // if (get_message_force(d, sent_message->reply_to_message_id) == nullptr) {
+  //   sent_message->reply_to_message_id = MessageId();
+  // }
+
+  bool is_content_changed = false;
+  if (new_file_id.is_valid()) {
+    int32 content_type = sent_message->content->get_id();
+    switch (content_type) {
+      case MessageAnimation::ID: {
+        auto content = static_cast<MessageAnimation *>(sent_message->content.get());
+        if (new_file_id != content->file_id) {
+          td_->animations_manager_->merge_animations(new_file_id, content->file_id, false);
+          content->file_id = new_file_id;
+          is_content_changed = true;
+        }
+        break;
+      }
+      case MessageAudio::ID: {
+        auto content = static_cast<MessageAudio *>(sent_message->content.get());
+        if (new_file_id != content->file_id) {
+          td_->audios_manager_->merge_audios(new_file_id, content->file_id, false);
+          content->file_id = new_file_id;
+          is_content_changed = true;
+        }
+        break;
+      }
+      case MessageDocument::ID: {
+        auto content = static_cast<MessageDocument *>(sent_message->content.get());
+        if (new_file_id != content->file_id) {
+          td_->documents_manager_->merge_documents(new_file_id, content->file_id, false);
+          content->file_id = new_file_id;
+          is_content_changed = true;
+        }
+        break;
+      }
+      case MessagePhoto::ID: {
+        auto content = static_cast<MessagePhoto *>(sent_message->content.get());
+        Photo *photo = &content->photo;
+        if (!photo->photos.empty() && photo->photos.back().type == 'i') {
+          FileId &old_file_id = photo->photos.back().file_id;
+          if (old_file_id != new_file_id) {
+            LOG_STATUS(td_->file_manager_->merge(new_file_id, old_file_id));
+            old_file_id = new_file_id;
+            is_content_changed = true;
+          }
+        }
+        break;
+      }
+      case MessageSticker::ID: {
+        auto content = static_cast<MessageSticker *>(sent_message->content.get());
+        if (new_file_id != content->file_id) {
+          td_->stickers_manager_->merge_stickers(new_file_id, content->file_id, false);
+          content->file_id = new_file_id;
+          is_content_changed = true;
+        }
+        break;
+      }
+      case MessageVideo::ID: {
+        auto content = static_cast<MessageVideo *>(sent_message->content.get());
+        if (new_file_id != content->file_id) {
+          td_->videos_manager_->merge_videos(new_file_id, content->file_id, false);
+          content->file_id = new_file_id;
+          is_content_changed = true;
+        }
+        break;
+      }
+      case MessageVideoNote::ID: {
+        auto content = static_cast<MessageVideoNote *>(sent_message->content.get());
+        if (new_file_id != content->file_id) {
+          td_->video_notes_manager_->merge_video_notes(new_file_id, content->file_id, false);
+          content->file_id = new_file_id;
+          is_content_changed = true;
+        }
+        break;
+      }
+      case MessageVoiceNote::ID: {
+        auto content = static_cast<MessageVoiceNote *>(sent_message->content.get());
+        if (new_file_id != content->file_id) {
+          td_->voice_notes_manager_->merge_voice_notes(new_file_id, content->file_id, false);
+          content->file_id = new_file_id;
+          is_content_changed = true;
+        }
+        break;
+      }
+      case MessageContact::ID:
+      case MessageGame::ID:
+      case MessageInvoice::ID:
+      case MessageLiveLocation::ID:
+      case MessageLocation::ID:
+      case MessageText::ID:
+      case MessageVenue::ID:
+      case MessageChatCreate::ID:
+      case MessageChatChangeTitle::ID:
+      case MessageChatChangePhoto::ID:
+      case MessageChatDeletePhoto::ID:
+      case MessageChatDeleteHistory::ID:
+      case MessageChatAddUsers::ID:
+      case MessageChatJoinedByLink::ID:
+      case MessageChatDeleteUser::ID:
+      case MessageChatMigrateTo::ID:
+      case MessageChannelCreate::ID:
+      case MessageChannelMigrateFrom::ID:
+      case MessagePinMessage::ID:
+      case MessageGameScore::ID:
+      case MessageScreenshotTaken::ID:
+      case MessageChatSetTtl::ID:
+      case MessageUnsupported::ID:
+      case MessageCall::ID:
+      case MessagePaymentSuccessful::ID:
+      case MessageContactRegistered::ID:
+      case MessageExpiredPhoto::ID:
+      case MessageExpiredVideo::ID:
+      case MessageCustomServiceAction::ID:
+      case MessageWebsiteConnected::ID:
+        LOG(ERROR) << "Receive new file " << new_file_id << " in a sent message of the type " << content_type;
+        break;
+      default:
+        UNREACHABLE();
+        break;
+    }
+  }
+  if (is_content_changed) {
+    send_update_message_content(dialog_id, old_message_id, sent_message->content.get(), sent_message->date,
+                                sent_message->is_content_secret, source);
+  }
+
+  sent_message->message_id = new_message_id;
+  sent_message->random_y = get_random_y(sent_message->message_id);
+
+  sent_message->have_previous = true;
+  sent_message->have_next = true;
+
+  bool need_update = true;
+  Message *m = add_message_to_dialog(d, std::move(sent_message), true, &need_update, &need_update_dialog_pos, source);
+  CHECK(m != nullptr);
+
+  send_update_message_send_succeeded(d, old_message_id, m);
+  if (need_update_dialog_pos) {
+    send_update_chat_last_message(d, "on_send_message_success");
+  }
+  try_add_active_live_location(dialog_id, m);
+  return {dialog_id, new_message_id};
+}
+
+void MessagesManager::on_send_message_file_part_missing(int64 random_id, int bad_part) {
+  auto it = being_sent_messages_.find(random_id);
+  if (it == being_sent_messages_.end()) {
+    // we can't receive fail more than once
+    // but message can be successfully sent before
+    LOG(WARNING) << "Receive FILE_PART_" << bad_part
+                 << "_MISSING about successfully sent message with random_id = " << random_id;
+    return;
+  }
+
+  auto full_message_id = it->second;
+
+  being_sent_messages_.erase(it);
+
+  Message *m = get_message(full_message_id);
+  if (m == nullptr) {
+    // message has already been deleted by the user or sent to inaccessible channel
+    // don't need to send error to the user, because the message has already been deleted
+    // and there is nothing to be deleted from the server
+    LOG(INFO) << "Fail to send already deleted by the user or sent to inaccessible chat " << full_message_id;
+    return;
+  }
+
+  auto dialog_id = full_message_id.get_dialog_id();
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    // LOG(ERROR) << "Found " << m->message_id << " in inaccessible " << dialog_id;
+    // dump_debug_message_op(get_dialog(dialog_id), 5);
+  }
+
+  Dialog *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+  if (dialog_id.get_type() == DialogType::SecretChat) {
+    // need to change message random_id before resending
+    do {
+      m->random_id = Random::secure_int64();
+    } while (m->random_id == 0 || message_random_ids_.find(m->random_id) != message_random_ids_.end());
+    message_random_ids_.insert(m->random_id);
+
+    LOG(INFO) << "Replace random_id from " << random_id << " to " << m->random_id << " in " << m->message_id << " in "
+              << dialog_id;
+    d->random_id_to_message_id.erase(random_id);
+    d->random_id_to_message_id[m->random_id] = m->message_id;
+
+    auto logevent = SendMessageLogEvent(dialog_id, m);
+    auto storer = LogEventStorerImpl<SendMessageLogEvent>(logevent);
+    CHECK(m->send_message_logevent_id != 0);
+    BinlogHelper::rewrite(G()->td_db()->get_binlog(), m->send_message_logevent_id, LogEvent::HandlerType::SendMessage,
+                          storer);
+  }
+
+  do_send_message(dialog_id, m, {bad_part});
+}
+
+void MessagesManager::on_send_message_fail(int64 random_id, Status error) {
+  CHECK(error.is_error());
+
+  auto it = being_sent_messages_.find(random_id);
+  if (it == being_sent_messages_.end()) {
+    // we can't receive fail more than once
+    // but message can be successfully sent before
+    if (error.code() != NetQuery::Cancelled) {
+      auto debug_it = debug_being_sent_messages_.find(random_id);
+      if (debug_it == debug_being_sent_messages_.end()) {
+        LOG(ERROR) << "Message with random_id " << random_id << " was not sent";
+        return;
+      }
+      auto dialog_id = debug_it->second;
+      if (!dialog_id.is_valid()) {
+        LOG(ERROR) << "Sent message is in invalid " << dialog_id;
+        return;
+      }
+      if (!have_dialog(dialog_id)) {
+        LOG(ERROR) << "Sent message is in not found " << dialog_id;
+        return;
+      }
+      LOG(ERROR) << "Receive error " << error << " about successfully sent message with random_id = " << random_id
+                 << " in " << dialog_id;
+      dump_debug_message_op(get_dialog(dialog_id), 7);
+    }
+    return;
+  }
+
+  auto full_message_id = it->second;
+
+  being_sent_messages_.erase(it);
+
+  Message *m = get_message(full_message_id);
+  if (m == nullptr) {
+    // message has already been deleted by the user or sent to inaccessible channel
+    // don't need to send error to the user, because the message has already been deleted
+    // and there is nothing to be deleted from the server
+    LOG(INFO) << "Fail to send already deleted by the user or sent to inaccessible chat " << full_message_id;
+    return;
+  }
+  LOG_IF(ERROR, error.code() == NetQuery::Cancelled)
+      << "Receive error " << error << " about sent message with random_id = " << random_id;
+
+  auto dialog_id = full_message_id.get_dialog_id();
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    // LOG(ERROR) << "Found " << m->message_id << " in inaccessible " << dialog_id;
+    // dump_debug_message_op(get_dialog(dialog_id), 5);
+  }
+
+  int error_code = error.code();
+  string error_message = error.message().str();
+  switch (error_code) {
+    case 420:
+      error_code = 429;
+      LOG(ERROR) << "Receive error 420: " << error_message;
+      break;
+    case 429:
+      // nothing special, error description has already been changed
+      LOG_IF(ERROR, !begins_with(error_message, "Too Many Requests: retry after "))
+          << "Wrong error message: " << error_message;
+      break;
+    case 400:
+      if (error.message() == "MESSAGE_TOO_LONG") {
+        error_message = "Message is too long";
+        // TODO move check to send_message
+      } else if (error.message() == "INPUT_USER_DEACTIVATED") {
+        error_code = 403;
+        error_message = "User is deactivated";
+      } else if (error.message() == "USER_IS_BLOCKED") {
+        error_code = 403;
+        if (td_->auth_manager_->is_bot()) {
+          switch (dialog_id.get_type()) {
+            case DialogType::User:
+              error_message = "Bot was blocked by the user";
+              break;
+            case DialogType::Chat:
+            case DialogType::Channel:
+              error_message = "Bot was kicked from the chat";
+              break;
+            case DialogType::SecretChat:
+              break;
+            case DialogType::None:
+            default:
+              UNREACHABLE();
+          }
+        } else {
+          switch (dialog_id.get_type()) {
+            case DialogType::User:
+              error_message = "User was blocked by the other user";
+              break;
+            case DialogType::Chat:
+            case DialogType::Channel:
+              error_message = "User is not in the chat";
+              break;
+            case DialogType::SecretChat:
+              break;
+            case DialogType::None:
+            default:
+              UNREACHABLE();
+          }
+        }
+        // TODO add check to send_message
+      } else if (error.message() == "USER_IS_BOT") {
+        error_code = 403;
+        error_message = "Bot can't send messages to bots";
+        // TODO move check to send_message
+      } else if (error.message() == "PEER_ID_INVALID") {
+        error_code = 403;
+        error_message = "Bot can't initiate conversation with a user";
+      } else if (error.message() == "WC_CONVERT_URL_INVALID" || error.message() == "EXTERNAL_URL_INVALID") {
+        error_message = "Wrong HTTP URL specified";
+      } else if (error.message() == "WEBPAGE_CURL_FAILED") {
+        error_message = "Failed to get HTTP URL content";
+      } else if (error.message() == "WEBPAGE_MEDIA_EMPTY") {
+        error_message = "Wrong type of the web page content";
+      } else if (error.message() == "MEDIA_EMPTY") {
+        auto content_type = m->content->get_id();
+        if (content_type == MessageGame::ID) {
+          error_message = "Wrong game short name specified";
+        } else if (content_type == MessageInvoice::ID) {
+          error_message = "Wrong invoice information specified";
+        } else {
+          error_message = "Wrong file identifier/HTTP URL specified";
+        }
+      } else if (error.message() == "PHOTO_EXT_INVALID") {
+        error_message = "Photo has unsupported extension. Use one of .jpg, .jpeg, .gif, .png, .tif or .bmp";
+      }
+      break;
+    case 403:
+      if (error.message() == "MESSAGE_DELETE_FORBIDDEN") {
+        error_code = 400;
+        error_message = "Message can't be deleted";
+      } else if (error.message() != "CHANNEL_PUBLIC_GROUP_NA" && error.message() != "USER_IS_BLOCKED" &&
+                 error.message() != "USER_BOT_INVALID" && error.message() != "USER_DELETED") {
+        error_code = 400;
+      }
+      break;
+    // TODO other codes
+    default:
+      break;
+  }
+  if (error.message() == "REPLY_MARKUP_INVALID") {
+    if (m->reply_markup == nullptr) {
+      LOG(ERROR) << "Receive " << error.message() << " for " << oneline(to_string(get_message_object(dialog_id, m)));
+    } else {
+      LOG(ERROR) << "Receive " << error.message() << " for " << full_message_id << " with keyboard "
+                 << *m->reply_markup;
+    }
+  }
+  LOG_IF(WARNING, error_code != 403) << "Fail to send " << full_message_id << " with the error " << error;
+  if (error_code <= 0) {
+    error_code = 500;
+  }
+  fail_send_message(full_message_id, error_code, error_message);
+}
+
+MessageId MessagesManager::get_next_message_id(Dialog *d, int32 type) {
+  CHECK(d != nullptr);
+  int64 last = std::max({d->last_message_id.get(), d->last_new_message_id.get(), d->last_database_message_id.get(),
+                         d->last_assigned_message_id.get(), d->last_clear_history_message_id.get(),
+                         d->deleted_last_message_id.get(), d->max_unavailable_message_id.get()});
+  if (last < d->last_read_inbox_message_id.get() &&
+      d->last_read_inbox_message_id.get() < d->last_new_message_id.get() + MessageId::FULL_TYPE_MASK) {
+    last = d->last_read_inbox_message_id.get();
+  }
+  if (last < d->last_read_outbox_message_id.get() &&
+      d->last_read_outbox_message_id.get() < d->last_new_message_id.get() + MessageId::FULL_TYPE_MASK) {
+    last = d->last_read_outbox_message_id.get();
+  }
+
+  int64 base = (last + MessageId::TYPE_MASK + 1) & ~MessageId::TYPE_MASK;
+  d->last_assigned_message_id = MessageId(base + type);
+  return d->last_assigned_message_id;
+}
+
+MessageId MessagesManager::get_next_yet_unsent_message_id(Dialog *d) {
+  return get_next_message_id(d, MessageId::TYPE_YET_UNSENT);
+}
+
+MessageId MessagesManager::get_next_local_message_id(Dialog *d) {
+  return get_next_message_id(d, MessageId::TYPE_LOCAL);
+}
+
+void MessagesManager::fail_send_message(FullMessageId full_message_id, int error_code, const string &error_message) {
+  auto dialog_id = full_message_id.get_dialog_id();
+  Dialog *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+  MessageId old_message_id = full_message_id.get_message_id();
+  CHECK(old_message_id.is_yet_unsent());
+
+  bool need_update_dialog_pos = false;
+  unique_ptr<Message> message = delete_message(d, old_message_id, false, &need_update_dialog_pos, "fail send message");
+  if (message == nullptr) {
+    // message has already been deleted by the user or sent to inaccessible channel
+    // don't need to send update to the user, because the message has already been deleted
+    // and there is nothing to be deleted from the server
+    return;
+  }
+
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    // LOG(ERROR) << "Found " << old_message_id << " in inaccessible " << dialog_id;
+    // dump_debug_message_op(d, 5);
+  }
+
+  auto new_message_id = MessageId(old_message_id.get() - MessageId::TYPE_YET_UNSENT + MessageId::TYPE_LOCAL);
+  if (get_message_force(d, new_message_id) != nullptr || d->deleted_message_ids.count(new_message_id)) {
+    new_message_id = get_next_local_message_id(d);
+  }
+
+  message->message_id = new_message_id;
+  CHECK(message->message_id.is_valid());
+  message->random_y = get_random_y(message->message_id);
+  message->is_failed_to_send = true;
+
+  message->have_previous = true;
+  message->have_next = true;
+
+  bool need_update = false;
+  Message *m = add_message_to_dialog(dialog_id, std::move(message), false, &need_update, &need_update_dialog_pos,
+                                     "fail_send_message");
+  CHECK(m != nullptr) << "Failed to add failed to send " << new_message_id << " to " << dialog_id << " due to "
+                      << debug_add_message_to_dialog_fail_reason;
+
+  LOG(INFO) << "Send updateMessageSendFailed for " << full_message_id;
+  d->yet_unsent_message_id_to_persistent_message_id.emplace(old_message_id, m->message_id);
+  send_closure(G()->td(), &Td::send_update,
+               make_tl_object<td_api::updateMessageSendFailed>(get_message_object(dialog_id, m), old_message_id.get(),
+                                                               error_code, error_message));
+  if (need_update_dialog_pos) {
+    send_update_chat_last_message(d, "fail_send_message");
+  }
+}
+
+void MessagesManager::on_update_dialog_draft_message(DialogId dialog_id,
+                                                     tl_object_ptr<telegram_api::DraftMessage> &&draft_message) {
+  if (!dialog_id.is_valid()) {
+    LOG(ERROR) << "Receive update chat draft in invalid " << dialog_id;
+    return;
+  }
+  auto d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    LOG(INFO) << "Ignore update chat draft in unknown " << dialog_id;
+    return;
+  }
+  update_dialog_draft_message(d, get_draft_message(td_->contacts_manager_.get(), std::move(draft_message)), true, true);
+}
+
+bool MessagesManager::update_dialog_draft_message(Dialog *d, unique_ptr<DraftMessage> &&draft_message, bool from_update,
+                                                  bool need_update_dialog_pos) {
+  CHECK(d != nullptr);
+  if (from_update && d->is_opened && d->draft_message != nullptr) {
+    // send the update anyway, despite it shouldn't be applied client-side
+    // return false;
+  }
+  if (draft_message == nullptr) {
+    if (d->draft_message != nullptr) {
+      d->draft_message = nullptr;
+      if (need_update_dialog_pos) {
+        update_dialog_pos(d, false, "update_dialog_draft_message", false);
+      }
+      send_update_chat_draft_message(d);
+      return true;
+    }
+  } else {
+    if (d->draft_message != nullptr && d->draft_message->reply_to_message_id == draft_message->reply_to_message_id &&
+        d->draft_message->input_message_text == draft_message->input_message_text) {
+      if (d->draft_message->date < draft_message->date) {
+        if (need_update_dialog_pos) {
+          update_dialog_pos(d, false, "update_dialog_draft_message 2");
+        }
+        d->draft_message->date = draft_message->date;
+        return true;
+      }
+    } else {
+      if (!from_update || d->draft_message == nullptr || d->draft_message->date <= draft_message->date) {
+        d->draft_message = std::move(draft_message);
+        if (need_update_dialog_pos) {
+          update_dialog_pos(d, false, "update_dialog_draft_message 3", false);
+        }
+        send_update_chat_draft_message(d);
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+void MessagesManager::on_update_dialog_pinned(DialogId dialog_id, bool is_pinned) {
+  if (!dialog_id.is_valid()) {
+    LOG(ERROR) << "Receive pinn of invalid " << dialog_id;
+    return;
+  }
+  auto d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    LOG(WARNING) << "Can't apply updateDialogPinned with " << dialog_id;
+    // TODO logevent + promise
+    send_closure(td_->create_net_actor<GetPinnedDialogsQuery>(Promise<>()), &GetPinnedDialogsQuery::send,
+                 get_sequence_dispatcher_id(DialogId(), -1));
+    return;
+  }
+  if (!is_pinned && d->pinned_order == DEFAULT_ORDER) {
+    return;
+  }
+  set_dialog_is_pinned(d, is_pinned);
+  update_dialog_pos(d, false, "on_update_dialog_pinned");
+}
+
+void MessagesManager::on_update_pinned_dialogs() {
+  // TODO logevent + promise
+  send_closure(td_->create_net_actor<GetPinnedDialogsQuery>(Promise<>()), &GetPinnedDialogsQuery::send,
+               get_sequence_dispatcher_id(DialogId(), -1));
+}
+
+void MessagesManager::on_create_new_dialog_success(int64 random_id, tl_object_ptr<telegram_api::Updates> &&updates,
+                                                   DialogType expected_type, Promise<Unit> &&promise) {
+  auto sent_messages = td_->updates_manager_->get_new_messages(updates.get());
+  auto sent_messages_random_ids = td_->updates_manager_->get_sent_messages_random_ids(updates.get());
+  if (sent_messages.size() != 1u || sent_messages_random_ids.size() != 1u) {
+    LOG(ERROR) << "Receive wrong result for create group or channel chat " << oneline(to_string(updates));
+    return on_create_new_dialog_fail(random_id, Status::Error(500, "Unsupported server response"), std::move(promise));
+  }
+
+  auto message = *sent_messages.begin();
+  // int64 message_random_id = *sent_messages_random_ids.begin();
+  // TODO check that message_random_id equals random_id after messages_createChat will be updated
+
+  auto dialog_id = get_message_dialog_id(*message);
+  if (dialog_id.get_type() != expected_type) {
+    return on_create_new_dialog_fail(random_id, Status::Error(500, "Chat of wrong type has been created"),
+                                     std::move(promise));
+  }
+
+  auto it = created_dialogs_.find(random_id);
+  CHECK(it != created_dialogs_.end());
+  CHECK(it->second == DialogId());
+
+  it->second = dialog_id;
+
+  const Dialog *d = get_dialog(dialog_id);
+  if (d != nullptr && d->last_new_message_id.is_valid()) {
+    // dialog have been already created and at least one non-temporary message was added,
+    // i.e. we are not interested in the creation of dialog by searchMessages
+    // then messages have already been added, so just set promise
+    return promise.set_value(Unit());
+  }
+
+  if (pending_created_dialogs_.find(dialog_id) == pending_created_dialogs_.end()) {
+    pending_created_dialogs_.emplace(dialog_id, std::move(promise));
+  } else {
+    LOG(ERROR) << dialog_id << " returned twice as result of chat creation";
+    return on_create_new_dialog_fail(random_id, Status::Error(500, "Chat was created earlier"), std::move(promise));
+  }
+
+  td_->updates_manager_->on_get_updates(std::move(updates));
+}
+
+void MessagesManager::on_create_new_dialog_fail(int64 random_id, Status error, Promise<Unit> &&promise) {
+  LOG(INFO) << "Clean up creation of group or channel chat";
+  auto it = created_dialogs_.find(random_id);
+  CHECK(it != created_dialogs_.end());
+  CHECK(it->second == DialogId());
+  created_dialogs_.erase(it);
+
+  CHECK(error.is_error());
+  promise.set_error(std::move(error));
+
+  // repairing state by running get difference
+  td_->updates_manager_->get_difference("on_create_new_dialog_fail");
+}
+
+void MessagesManager::on_dialog_photo_updated(DialogId dialog_id) {
+  if (have_dialog(dialog_id)) {
+    send_closure(G()->td(), &Td::send_update,
+                 make_tl_object<td_api::updateChatPhoto>(
+                     dialog_id.get(), get_chat_photo_object(td_->file_manager_.get(), get_dialog_photo(dialog_id))));
+  }
+}
+
+void MessagesManager::on_dialog_title_updated(DialogId dialog_id) {
+  auto d = get_dialog(dialog_id);
+  if (d != nullptr) {
+    update_dialogs_hints(d);
+    send_closure(G()->td(), &Td::send_update,
+                 make_tl_object<td_api::updateChatTitle>(dialog_id.get(), get_dialog_title(dialog_id)));
+  }
+}
+
+DialogId MessagesManager::resolve_dialog_username(const string &username) {
+  auto it = resolved_usernames_.find(clean_username(username));
+  if (it != resolved_usernames_.end()) {
+    return it->second.dialog_id;
+  }
+
+  auto it2 = unaccessible_resolved_usernames_.find(clean_username(username));
+  if (it2 != unaccessible_resolved_usernames_.end()) {
+    return it2->second;
+  }
+
+  return DialogId();
+}
+
+DialogId MessagesManager::search_public_dialog(const string &username_to_search, bool force, Promise<Unit> &&promise) {
+  string username = clean_username(username_to_search);
+  if (username[0] == '@') {
+    username = username.substr(1);
+  }
+  if (username.empty()) {
+    promise.set_error(Status::Error(200, "Username is invalid"));
+    return DialogId();
+  }
+
+  DialogId dialog_id;
+  auto it = resolved_usernames_.find(username);
+  if (it != resolved_usernames_.end()) {
+    if (it->second.expires_at < Time::now()) {
+      td_->create_handler<ResolveUsernameQuery>(Promise<>())->send(username);
+    }
+    dialog_id = it->second.dialog_id;
+  } else {
+    auto it2 = unaccessible_resolved_usernames_.find(username);
+    if (it2 != unaccessible_resolved_usernames_.end()) {
+      dialog_id = it2->second;
+    }
+  }
+
+  if (dialog_id.is_valid()) {
+    if (have_input_peer(dialog_id, AccessRights::Read)) {
+      if (td_->auth_manager_->is_bot()) {
+        force_create_dialog(dialog_id, "search public dialog");
+      } else {
+        const Dialog *d = get_dialog_force(dialog_id);
+        if (d == nullptr || !d->notification_settings.is_synchronized) {
+          send_get_dialog_query(dialog_id, std::move(promise));
+          return DialogId();
+        }
+      }
+
+      promise.set_value(Unit());
+      return dialog_id;
+    } else {
+      // bot username maybe known despite there is no access_hash
+      if (force || dialog_id.get_type() != DialogType::User) {
+        force_create_dialog(dialog_id, "search public dialog");
+        promise.set_value(Unit());
+        return dialog_id;
+      }
+    }
+  }
+
+  td_->create_handler<ResolveUsernameQuery>(std::move(promise))->send(username);
+  return DialogId();
+}
+
+void MessagesManager::send_get_dialog_query(DialogId dialog_id, Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    return;
+  }
+  auto &promises = get_dialog_queries_[dialog_id];
+  promises.push_back(std::move(promise));
+  if (promises.size() != 1) {
+    // query has already been sent, just wait for the result
+    return;
+  }
+
+  td_->create_handler<GetDialogQuery>()->send(dialog_id);
+}
+
+void MessagesManager::on_get_dialog_success(DialogId dialog_id) {
+  auto it = get_dialog_queries_.find(dialog_id);
+  CHECK(it != get_dialog_queries_.end());
+  CHECK(it->second.size() > 0);
+  auto promises = std::move(it->second);
+  get_dialog_queries_.erase(it);
+
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+void MessagesManager::on_get_dialog_fail(DialogId dialog_id, Status &&error) {
+  auto it = get_dialog_queries_.find(dialog_id);
+  CHECK(it != get_dialog_queries_.end());
+  CHECK(it->second.size() > 0);
+  auto promises = std::move(it->second);
+  get_dialog_queries_.erase(it);
+
+  for (auto &promise : promises) {
+    promise.set_error(error.clone());
+  }
+}
+
+bool MessagesManager::is_update_about_username_change_received(DialogId dialog_id) const {
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      return td_->contacts_manager_->is_update_about_username_change_received(dialog_id.get_user_id());
+    case DialogType::Chat:
+      return true;
+    case DialogType::Channel: {
+      auto status = td_->contacts_manager_->get_channel_status(dialog_id.get_channel_id());
+      return status.is_member();
+    }
+    case DialogType::SecretChat:
+      return true;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      return false;
+  }
+}
+
+void MessagesManager::on_dialog_username_updated(DialogId dialog_id, const string &old_username,
+                                                 const string &new_username) {
+  auto d = get_dialog(dialog_id);
+  if (d != nullptr) {
+    update_dialogs_hints(d);
+  }
+  if (!old_username.empty() && old_username != new_username) {
+    resolved_usernames_.erase(clean_username(old_username));
+    unaccessible_resolved_usernames_.erase(clean_username(old_username));
+  }
+  if (!new_username.empty()) {
+    auto cache_time = is_update_about_username_change_received(dialog_id) ? USERNAME_CACHE_EXPIRE_TIME
+                                                                          : USERNAME_CACHE_EXPIRE_TIME_SHORT;
+    resolved_usernames_[clean_username(new_username)] = ResolvedUsername{dialog_id, Time::now() + cache_time};
+  }
+}
+
+void MessagesManager::on_resolved_username(const string &username, DialogId dialog_id) {
+  if (!dialog_id.is_valid()) {
+    LOG(ERROR) << "Resolve username \"" << username << "\" to invalid " << dialog_id;
+    return;
+  }
+
+  auto it = resolved_usernames_.find(clean_username(username));
+  if (it != resolved_usernames_.end()) {
+    LOG_IF(ERROR, it->second.dialog_id != dialog_id)
+        << "Resolve username \"" << username << "\" to " << dialog_id << ", but have it in " << it->second.dialog_id;
+    return;
+  }
+
+  unaccessible_resolved_usernames_[clean_username(username)] = dialog_id;
+}
+
+void MessagesManager::drop_username(const string &username) {
+  unaccessible_resolved_usernames_.erase(clean_username(username));
+
+  auto it = resolved_usernames_.find(clean_username(username));
+  if (it == resolved_usernames_.end()) {
+    return;
+  }
+
+  auto dialog_id = it->second.dialog_id;
+  if (have_input_peer(dialog_id, AccessRights::Read)) {
+    CHECK(dialog_id.get_type() != DialogType::SecretChat);
+    send_get_dialog_query(dialog_id, Auto());
+  }
+
+  resolved_usernames_.erase(it);
+}
+
+const DialogPhoto *MessagesManager::get_dialog_photo(DialogId dialog_id) const {
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      return td_->contacts_manager_->get_user_dialog_photo(dialog_id.get_user_id());
+    case DialogType::Chat:
+      return td_->contacts_manager_->get_chat_dialog_photo(dialog_id.get_chat_id());
+    case DialogType::Channel:
+      return td_->contacts_manager_->get_channel_dialog_photo(dialog_id.get_channel_id());
+    case DialogType::SecretChat:
+      return td_->contacts_manager_->get_secret_chat_dialog_photo(dialog_id.get_secret_chat_id());
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+string MessagesManager::get_dialog_title(DialogId dialog_id) const {
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      return td_->contacts_manager_->get_user_title(dialog_id.get_user_id());
+    case DialogType::Chat:
+      return td_->contacts_manager_->get_chat_title(dialog_id.get_chat_id());
+    case DialogType::Channel:
+      return td_->contacts_manager_->get_channel_title(dialog_id.get_channel_id());
+    case DialogType::SecretChat:
+      return td_->contacts_manager_->get_secret_chat_title(dialog_id.get_secret_chat_id());
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      return string();
+  }
+}
+
+string MessagesManager::get_dialog_username(DialogId dialog_id) const {
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      return td_->contacts_manager_->get_user_username(dialog_id.get_user_id());
+    case DialogType::Chat:
+      return string();
+    case DialogType::Channel:
+      return td_->contacts_manager_->get_channel_username(dialog_id.get_channel_id());
+    case DialogType::SecretChat:
+      return td_->contacts_manager_->get_secret_chat_username(dialog_id.get_secret_chat_id());
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      return string();
+  }
+}
+
+void MessagesManager::send_dialog_action(DialogId dialog_id, const tl_object_ptr<td_api::ChatAction> &action,
+                                         Promise<Unit> &&promise) {
+  if (action == nullptr) {
+    return promise.set_error(Status::Error(5, "Action must not be empty"));
+  }
+
+  if (!have_dialog_force(dialog_id)) {
+    return promise.set_error(Status::Error(5, "Chat not found"));
+  }
+
+  auto can_send_status = can_send_message(dialog_id);
+  if (can_send_status.is_error()) {
+    return promise.set_error(can_send_status.move_as_error());
+  }
+
+  if (dialog_id.get_type() == DialogType::SecretChat) {
+    tl_object_ptr<secret_api::SendMessageAction> send_action;
+    switch (action->get_id()) {
+      case td_api::chatActionCancel::ID:
+        send_action = make_tl_object<secret_api::sendMessageCancelAction>();
+        break;
+      case td_api::chatActionTyping::ID:
+        send_action = make_tl_object<secret_api::sendMessageTypingAction>();
+        break;
+      case td_api::chatActionRecordingVideo::ID:
+        send_action = make_tl_object<secret_api::sendMessageRecordVideoAction>();
+        break;
+      case td_api::chatActionUploadingVideo::ID:
+        send_action = make_tl_object<secret_api::sendMessageUploadVideoAction>();
+        break;
+      case td_api::chatActionRecordingVoiceNote::ID:
+        send_action = make_tl_object<secret_api::sendMessageRecordAudioAction>();
+        break;
+      case td_api::chatActionUploadingVoiceNote::ID:
+        send_action = make_tl_object<secret_api::sendMessageUploadAudioAction>();
+        break;
+      case td_api::chatActionUploadingPhoto::ID:
+        send_action = make_tl_object<secret_api::sendMessageUploadPhotoAction>();
+        break;
+      case td_api::chatActionUploadingDocument::ID:
+        send_action = make_tl_object<secret_api::sendMessageUploadDocumentAction>();
+        break;
+      case td_api::chatActionChoosingLocation::ID:
+        send_action = make_tl_object<secret_api::sendMessageGeoLocationAction>();
+        break;
+      case td_api::chatActionChoosingContact::ID:
+        send_action = make_tl_object<secret_api::sendMessageChooseContactAction>();
+        break;
+      case td_api::chatActionRecordingVideoNote::ID:
+        send_action = make_tl_object<secret_api::sendMessageRecordRoundAction>();
+        break;
+      case td_api::chatActionUploadingVideoNote::ID:
+        send_action = make_tl_object<secret_api::sendMessageUploadRoundAction>();
+        break;
+      case td_api::chatActionStartPlayingGame::ID:
+        return promise.set_error(Status::Error(5, "Games are unsupported in secret chats"));
+      default:
+        UNREACHABLE();
+    }
+    send_closure(G()->secret_chats_manager(), &SecretChatsManager::send_message_action, dialog_id.get_secret_chat_id(),
+                 std::move(send_action));
+    promise.set_value(Unit());
+    return;
+  }
+
+  tl_object_ptr<telegram_api::SendMessageAction> send_action;
+  switch (action->get_id()) {
+    case td_api::chatActionCancel::ID:
+      send_action = make_tl_object<telegram_api::sendMessageCancelAction>();
+      break;
+    case td_api::chatActionTyping::ID:
+      send_action = make_tl_object<telegram_api::sendMessageTypingAction>();
+      break;
+    case td_api::chatActionRecordingVideo::ID:
+      send_action = make_tl_object<telegram_api::sendMessageRecordVideoAction>();
+      break;
+    case td_api::chatActionUploadingVideo::ID: {
+      auto progress = static_cast<td_api::chatActionUploadingVideo &>(*action).progress_;
+      send_action = make_tl_object<telegram_api::sendMessageUploadVideoAction>(progress);
+      break;
+    }
+    case td_api::chatActionRecordingVoiceNote::ID:
+      send_action = make_tl_object<telegram_api::sendMessageRecordAudioAction>();
+      break;
+    case td_api::chatActionUploadingVoiceNote::ID: {
+      auto progress = static_cast<td_api::chatActionUploadingVoiceNote &>(*action).progress_;
+      send_action = make_tl_object<telegram_api::sendMessageUploadAudioAction>(progress);
+      break;
+    }
+    case td_api::chatActionUploadingPhoto::ID: {
+      auto progress = static_cast<td_api::chatActionUploadingPhoto &>(*action).progress_;
+      send_action = make_tl_object<telegram_api::sendMessageUploadPhotoAction>(progress);
+      break;
+    }
+    case td_api::chatActionUploadingDocument::ID: {
+      auto progress = static_cast<td_api::chatActionUploadingDocument &>(*action).progress_;
+      send_action = make_tl_object<telegram_api::sendMessageUploadDocumentAction>(progress);
+      break;
+    }
+    case td_api::chatActionChoosingLocation::ID:
+      send_action = make_tl_object<telegram_api::sendMessageGeoLocationAction>();
+      break;
+    case td_api::chatActionChoosingContact::ID:
+      send_action = make_tl_object<telegram_api::sendMessageChooseContactAction>();
+      break;
+    case td_api::chatActionStartPlayingGame::ID:
+      send_action = make_tl_object<telegram_api::sendMessageGamePlayAction>();
+      break;
+    case td_api::chatActionRecordingVideoNote::ID:
+      send_action = make_tl_object<telegram_api::sendMessageRecordRoundAction>();
+      break;
+    case td_api::chatActionUploadingVideoNote::ID: {
+      auto progress = static_cast<td_api::chatActionUploadingVideoNote &>(*action).progress_;
+      send_action = make_tl_object<telegram_api::sendMessageUploadRoundAction>(progress);
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+
+  auto &query_ref = set_typing_query_[dialog_id];
+  if (!query_ref.empty() && !td_->auth_manager_->is_bot()) {
+    LOG(INFO) << "Cancel previous set typing query";
+    cancel_query(query_ref);
+  }
+  query_ref = td_->create_handler<SetTypingQuery>(std::move(promise))->send(dialog_id, std::move(send_action));
+}
+
+void MessagesManager::on_send_dialog_action_timeout(DialogId dialog_id) {
+  LOG(INFO) << "Receive send_dialog_action timeout in " << dialog_id;
+  Dialog *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+
+  if (can_send_message(dialog_id).is_error()) {
+    return;
+  }
+
+  auto queue_id = get_sequence_dispatcher_id(dialog_id, MessagePhoto::ID);
+  CHECK(queue_id & 1);
+
+  auto queue_it = yet_unsent_media_queues_.find(queue_id);
+  if (queue_it == yet_unsent_media_queues_.end()) {
+    return;
+  }
+
+  pending_send_dialog_action_timeout_.add_timeout_in(dialog_id.get(), 4.0);
+
+  CHECK(!queue_it->second.empty());
+  MessageId message_id(queue_it->second.begin()->first);
+  const Message *m = get_message(d, message_id);
+  if (m == nullptr) {
+    return;
+  }
+  if (m->forward_info != nullptr) {
+    return;
+  }
+
+  auto file_id = get_message_content_file_id(m->content.get());
+  if (!file_id.is_valid()) {
+    LOG(ERROR) << "Have no file in "
+               << to_string(get_message_content_object(m->content.get(), m->date, m->is_content_secret));
+    return;
+  }
+  auto file_view = td_->file_manager_->get_file_view(file_id);
+  if (!file_view.is_uploading()) {
+    return;
+  }
+  int64 total_size = file_view.expected_size();
+  int64 uploaded_size = file_view.remote_size();
+  int32 progress = 0;
+  if (total_size > 0 && uploaded_size > 0) {
+    if (uploaded_size > total_size) {
+      uploaded_size = total_size;  // just in case
+    }
+    progress = static_cast<int32>(100 * uploaded_size / total_size);
+  }
+
+  td_api::object_ptr<td_api::ChatAction> action;
+  switch (m->content->get_id()) {
+    case MessageAnimation::ID:
+    case MessageAudio::ID:
+    case MessageDocument::ID:
+      action = td_api::make_object<td_api::chatActionUploadingDocument>(progress);
+      break;
+    case MessagePhoto::ID:
+      action = td_api::make_object<td_api::chatActionUploadingPhoto>(progress);
+      break;
+    case MessageVideo::ID:
+      action = td_api::make_object<td_api::chatActionUploadingVideo>(progress);
+      break;
+    case MessageVideoNote::ID:
+      action = td_api::make_object<td_api::chatActionUploadingVideoNote>(progress);
+      break;
+    case MessageVoiceNote::ID:
+      action = td_api::make_object<td_api::chatActionUploadingVoiceNote>(progress);
+      break;
+    default:
+      return;
+  }
+  CHECK(action != nullptr);
+  LOG(INFO) << "Send action in " << dialog_id << ": " << to_string(action);
+  send_dialog_action(dialog_id, std::move(action), Auto());
+}
+
+void MessagesManager::on_active_dialog_action_timeout(DialogId dialog_id) {
+  LOG(DEBUG) << "Receive active dialog action timeout in " << dialog_id;
+  Dialog *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+
+  auto actions_it = active_dialog_actions_.find(dialog_id);
+  if (actions_it == active_dialog_actions_.end()) {
+    return;
+  }
+  CHECK(!actions_it->second.empty());
+
+  auto now = Time::now();
+  while (actions_it->second[0].start_time + DIALOG_ACTION_TIMEOUT < now + 0.1) {
+    on_user_dialog_action(dialog_id, actions_it->second[0].user_id, nullptr);
+
+    actions_it = active_dialog_actions_.find(dialog_id);
+    if (actions_it == active_dialog_actions_.end()) {
+      return;
+    }
+    CHECK(!actions_it->second.empty());
+  }
+
+  LOG(DEBUG) << "Schedule next action timeout in " << dialog_id;
+  active_dialog_action_timeout_.add_timeout_in(dialog_id.get(),
+                                               actions_it->second[0].start_time + DIALOG_ACTION_TIMEOUT - now);
+}
+
+tl_object_ptr<telegram_api::InputChatPhoto> MessagesManager::get_input_chat_photo(FileId file_id) const {
+  if (!file_id.is_valid()) {
+    return make_tl_object<telegram_api::inputChatPhotoEmpty>();
+  }
+
+  FileView file_view = td_->file_manager_->get_file_view(file_id);
+  CHECK(!file_view.is_encrypted());
+  if (file_view.has_remote_location()) {
+    if (file_view.remote_location().is_web()) {
+      return nullptr;
+    }
+    return make_tl_object<telegram_api::inputChatPhoto>(file_view.remote_location().as_input_photo());
+  }
+
+  return nullptr;
+}
+
+tl_object_ptr<telegram_api::MessagesFilter> MessagesManager::get_input_messages_filter(SearchMessagesFilter filter) {
+  switch (filter) {
+    case SearchMessagesFilter::Empty:
+      return make_tl_object<telegram_api::inputMessagesFilterEmpty>();
+    case SearchMessagesFilter::Animation:
+      return make_tl_object<telegram_api::inputMessagesFilterGif>();
+    case SearchMessagesFilter::Audio:
+      return make_tl_object<telegram_api::inputMessagesFilterMusic>();
+    case SearchMessagesFilter::Document:
+      return make_tl_object<telegram_api::inputMessagesFilterDocument>();
+    case SearchMessagesFilter::Photo:
+      return make_tl_object<telegram_api::inputMessagesFilterPhotos>();
+    case SearchMessagesFilter::Video:
+      return make_tl_object<telegram_api::inputMessagesFilterVideo>();
+    case SearchMessagesFilter::VoiceNote:
+      return make_tl_object<telegram_api::inputMessagesFilterVoice>();
+    case SearchMessagesFilter::PhotoAndVideo:
+      return make_tl_object<telegram_api::inputMessagesFilterPhotoVideo>();
+    case SearchMessagesFilter::Url:
+      return make_tl_object<telegram_api::inputMessagesFilterUrl>();
+    case SearchMessagesFilter::ChatPhoto:
+      return make_tl_object<telegram_api::inputMessagesFilterChatPhotos>();
+    case SearchMessagesFilter::Call:
+      return make_tl_object<telegram_api::inputMessagesFilterPhoneCalls>(0, false /*ignored*/);
+    case SearchMessagesFilter::MissedCall:
+      return make_tl_object<telegram_api::inputMessagesFilterPhoneCalls>(
+          telegram_api::inputMessagesFilterPhoneCalls::MISSED_MASK, false /*ignored*/);
+    case SearchMessagesFilter::VideoNote:
+      return make_tl_object<telegram_api::inputMessagesFilterRoundVideo>();
+    case SearchMessagesFilter::VoiceAndVideoNote:
+      return make_tl_object<telegram_api::inputMessagesFilterRoundVoice>();
+    case SearchMessagesFilter::Mention:
+      return make_tl_object<telegram_api::inputMessagesFilterMyMentions>();
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+SearchMessagesFilter MessagesManager::get_search_messages_filter(
+    const tl_object_ptr<td_api::SearchMessagesFilter> &filter) {
+  if (filter == nullptr) {
+    return SearchMessagesFilter::Empty;
+  }
+  switch (filter->get_id()) {
+    case td_api::searchMessagesFilterEmpty::ID:
+      return SearchMessagesFilter::Empty;
+    case td_api::searchMessagesFilterAnimation::ID:
+      return SearchMessagesFilter::Animation;
+    case td_api::searchMessagesFilterAudio::ID:
+      return SearchMessagesFilter::Audio;
+    case td_api::searchMessagesFilterDocument::ID:
+      return SearchMessagesFilter::Document;
+    case td_api::searchMessagesFilterPhoto::ID:
+      return SearchMessagesFilter::Photo;
+    case td_api::searchMessagesFilterVideo::ID:
+      return SearchMessagesFilter::Video;
+    case td_api::searchMessagesFilterVoiceNote::ID:
+      return SearchMessagesFilter::VoiceNote;
+    case td_api::searchMessagesFilterPhotoAndVideo::ID:
+      return SearchMessagesFilter::PhotoAndVideo;
+    case td_api::searchMessagesFilterUrl::ID:
+      return SearchMessagesFilter::Url;
+    case td_api::searchMessagesFilterChatPhoto::ID:
+      return SearchMessagesFilter::ChatPhoto;
+    case td_api::searchMessagesFilterCall::ID:
+      return SearchMessagesFilter::Call;
+    case td_api::searchMessagesFilterMissedCall::ID:
+      return SearchMessagesFilter::MissedCall;
+    case td_api::searchMessagesFilterVideoNote::ID:
+      return SearchMessagesFilter::VideoNote;
+    case td_api::searchMessagesFilterVoiceAndVideoNote::ID:
+      return SearchMessagesFilter::VoiceAndVideoNote;
+    case td_api::searchMessagesFilterMention::ID:
+      return SearchMessagesFilter::Mention;
+    case td_api::searchMessagesFilterUnreadMention::ID:
+      return SearchMessagesFilter::UnreadMention;
+    default:
+      UNREACHABLE();
+      return SearchMessagesFilter::Empty;
+  }
+}
+
+void MessagesManager::set_dialog_photo(DialogId dialog_id, const tl_object_ptr<td_api::InputFile> &photo,
+                                       Promise<Unit> &&promise) {
+  LOG(INFO) << "Receive SetChatPhoto request to change photo of " << dialog_id;
+
+  if (!have_dialog_force(dialog_id)) {
+    return promise.set_error(Status::Error(3, "Chat not found"));
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      return promise.set_error(Status::Error(3, "Can't change private chat photo"));
+    case DialogType::Chat: {
+      auto chat_id = dialog_id.get_chat_id();
+      auto status = td_->contacts_manager_->get_chat_status(chat_id);
+      if (!status.can_change_info_and_settings() ||
+          (td_->auth_manager_->is_bot() && !td_->contacts_manager_->is_appointed_chat_administrator(chat_id))) {
+        return promise.set_error(Status::Error(3, "Not enough rights to change chat photo"));
+      }
+      break;
+    }
+    case DialogType::Channel: {
+      auto status = td_->contacts_manager_->get_channel_status(dialog_id.get_channel_id());
+      if (!status.can_change_info_and_settings()) {
+        return promise.set_error(Status::Error(3, "Not enough rights to change chat photo"));
+      }
+      break;
+    }
+    case DialogType::SecretChat:
+      return promise.set_error(Status::Error(3, "Can't change secret chat photo"));
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+
+  auto r_file_id = td_->file_manager_->get_input_file_id(FileType::Photo, photo, dialog_id, true, false);
+  if (r_file_id.is_error()) {
+    return promise.set_error(Status::Error(7, r_file_id.error().message()));
+  }
+  FileId file_id = r_file_id.ok();
+
+  auto input_chat_photo = get_input_chat_photo(file_id);
+  if (input_chat_photo != nullptr) {
+    // file has already been uploaded, just send change photo request
+    // TODO invoke after
+    td_->create_handler<EditDialogPhotoQuery>(std::move(promise))
+        ->send(FileId(), dialog_id, std::move(input_chat_photo));
+    return;
+  }
+
+  // need to upload file first
+  auto upload_file_id = td_->file_manager_->dup_file_id(file_id);
+  CHECK(upload_file_id.is_valid());
+  CHECK(uploaded_dialog_photos_.find(upload_file_id) == uploaded_dialog_photos_.end());
+  uploaded_dialog_photos_[upload_file_id] = {std::move(promise), dialog_id};
+  LOG(INFO) << "Ask to upload chat photo " << upload_file_id;
+  td_->file_manager_->upload(upload_file_id, upload_dialog_photo_callback_, 1, 0);
+}
+
+void MessagesManager::set_dialog_title(DialogId dialog_id, const string &title, Promise<Unit> &&promise) {
+  LOG(INFO) << "Receive SetChatTitle request to change title of " << dialog_id << " to \"" << title << '"';
+
+  if (!have_dialog_force(dialog_id)) {
+    return promise.set_error(Status::Error(3, "Chat not found"));
+  }
+
+  auto new_title = clean_name(title, MAX_NAME_LENGTH);
+  if (new_title.empty()) {
+    return promise.set_error(Status::Error(3, "Title can't be empty"));
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      return promise.set_error(Status::Error(3, "Can't change private chat title"));
+    case DialogType::Chat: {
+      auto chat_id = dialog_id.get_chat_id();
+      auto status = td_->contacts_manager_->get_chat_status(chat_id);
+      if (!status.can_change_info_and_settings() ||
+          (td_->auth_manager_->is_bot() && !td_->contacts_manager_->is_appointed_chat_administrator(chat_id))) {
+        return promise.set_error(Status::Error(3, "Not enough rights to change chat title"));
+      }
+      break;
+    }
+    case DialogType::Channel: {
+      auto status = td_->contacts_manager_->get_channel_status(dialog_id.get_channel_id());
+      if (!status.can_change_info_and_settings()) {
+        return promise.set_error(Status::Error(3, "Not enough rights to change chat title"));
+      }
+      break;
+    }
+    case DialogType::SecretChat:
+      return promise.set_error(Status::Error(3, "Can't change secret chat title"));
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+
+  // TODO this can be wrong if there was previous change title requests
+  if (get_dialog_title(dialog_id) == new_title) {
+    return promise.set_value(Unit());
+  }
+
+  // TODO invoke after
+  td_->create_handler<EditDialogTitleQuery>(std::move(promise))->send(dialog_id, new_title);
+}
+
+void MessagesManager::add_dialog_participant(DialogId dialog_id, UserId user_id, int32 forward_limit,
+                                             Promise<Unit> &&promise) {
+  LOG(INFO) << "Receive AddChatParticipant request to add " << user_id << " to " << dialog_id;
+  if (!have_dialog_force(dialog_id)) {
+    return promise.set_error(Status::Error(3, "Chat not found"));
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      return promise.set_error(Status::Error(3, "Can't add members to a private chat"));
+    case DialogType::Chat:
+      return td_->contacts_manager_->add_chat_participant(dialog_id.get_chat_id(), user_id, forward_limit,
+                                                          std::move(promise));
+    case DialogType::Channel:
+      return td_->contacts_manager_->add_channel_participant(dialog_id.get_channel_id(), user_id, std::move(promise));
+    case DialogType::SecretChat:
+      return promise.set_error(Status::Error(3, "Can't add members to a secret chat"));
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+}
+
+void MessagesManager::add_dialog_participants(DialogId dialog_id, const vector<UserId> &user_ids,
+                                              Promise<Unit> &&promise) {
+  LOG(INFO) << "Receive AddChatParticipants request to add " << format::as_array(user_ids) << " to " << dialog_id;
+  if (td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(3, "Method is not available for bots"));
+  }
+
+  if (!have_dialog_force(dialog_id)) {
+    return promise.set_error(Status::Error(3, "Chat not found"));
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      return promise.set_error(Status::Error(3, "Can't add members to a private chat"));
+    case DialogType::Chat:
+      return promise.set_error(Status::Error(3, "Can't add many members at once to a basic group chat"));
+    case DialogType::Channel:
+      return td_->contacts_manager_->add_channel_participants(dialog_id.get_channel_id(), user_ids, std::move(promise));
+    case DialogType::SecretChat:
+      return promise.set_error(Status::Error(3, "Can't add members to a secret chat"));
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+}
+
+void MessagesManager::set_dialog_participant_status(DialogId dialog_id, UserId user_id,
+                                                    const tl_object_ptr<td_api::ChatMemberStatus> &chat_member_status,
+                                                    Promise<Unit> &&promise) {
+  auto status = get_dialog_participant_status(chat_member_status);
+  LOG(INFO) << "Receive SetChatMemberStatus request with " << user_id << " and " << dialog_id << " to " << status;
+  if (!have_dialog_force(dialog_id)) {
+    return promise.set_error(Status::Error(3, "Chat not found"));
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      return promise.set_error(Status::Error(3, "Chat member status can't be changed in private chats"));
+    case DialogType::Chat:
+      return td_->contacts_manager_->change_chat_participant_status(dialog_id.get_chat_id(), user_id, status,
+                                                                    std::move(promise));
+    case DialogType::Channel:
+      return td_->contacts_manager_->change_channel_participant_status(dialog_id.get_channel_id(), user_id, status,
+                                                                       std::move(promise));
+    case DialogType::SecretChat:
+      return promise.set_error(Status::Error(3, "Chat member status can't be changed in secret chats"));
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+}
+
+DialogParticipant MessagesManager::get_dialog_participant(DialogId dialog_id, UserId user_id, int64 &random_id,
+                                                          bool force, Promise<Unit> &&promise) {
+  LOG(INFO) << "Receive GetChatMember request to get " << user_id << " in " << dialog_id;
+  if (!have_dialog_force(dialog_id)) {
+    promise.set_error(Status::Error(3, "Chat not found"));
+    return DialogParticipant();
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User: {
+      auto peer_user_id = dialog_id.get_user_id();
+      if (user_id == td_->contacts_manager_->get_my_id("get_dialog_participant")) {
+        promise.set_value(Unit());
+        return {user_id, peer_user_id, 0, DialogParticipantStatus::Member()};
+      }
+      if (user_id == peer_user_id) {
+        promise.set_value(Unit());
+        return {peer_user_id, user_id, 0, DialogParticipantStatus::Member()};
+      }
+
+      promise.set_error(Status::Error(3, "User is not a member of the private chat"));
+      break;
+    }
+    case DialogType::Chat:
+      return td_->contacts_manager_->get_chat_participant(dialog_id.get_chat_id(), user_id, force, std::move(promise));
+    case DialogType::Channel:
+      return td_->contacts_manager_->get_channel_participant(dialog_id.get_channel_id(), user_id, random_id, force,
+                                                             std::move(promise));
+    case DialogType::SecretChat: {
+      auto peer_user_id = td_->contacts_manager_->get_secret_chat_user_id(dialog_id.get_secret_chat_id());
+      if (user_id == td_->contacts_manager_->get_my_id("get_dialog_participant")) {
+        promise.set_value(Unit());
+        return {user_id, peer_user_id, 0, DialogParticipantStatus::Member()};
+      }
+      if (user_id == peer_user_id) {
+        promise.set_value(Unit());
+        return {peer_user_id, user_id, 0, DialogParticipantStatus::Member()};
+      }
+
+      promise.set_error(Status::Error(3, "User is not a member of the secret chat"));
+      break;
+    }
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      promise.set_error(Status::Error(500, "Wrong chat type"));
+  }
+  return DialogParticipant();
+}
+
+std::pair<int32, vector<DialogParticipant>> MessagesManager::search_private_chat_participants(UserId my_user_id,
+                                                                                              UserId peer_user_id,
+                                                                                              const string &query,
+                                                                                              int32 limit) const {
+  auto result = td_->contacts_manager_->search_among_users({my_user_id, peer_user_id}, query, limit);
+  return {result.first, transform(result.second, [&](UserId user_id) {
+            return DialogParticipant(user_id, user_id == my_user_id ? peer_user_id : my_user_id, 0,
+                                     DialogParticipantStatus::Member());
+          })};
+}
+
+std::pair<int32, vector<DialogParticipant>> MessagesManager::search_dialog_participants(
+    DialogId dialog_id, const string &query, int32 limit, int64 &random_id, bool force, Promise<Unit> &&promise) {
+  LOG(INFO) << "Receive SearchChatMembers request to search for " << query << " in " << dialog_id;
+  if (!have_dialog_force(dialog_id)) {
+    promise.set_error(Status::Error(3, "Chat not found"));
+    return {};
+  }
+  if (limit < 0) {
+    promise.set_error(Status::Error(3, "Parameter limit must be non-negative"));
+    return {};
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      promise.set_value(Unit());
+      return search_private_chat_participants(td_->contacts_manager_->get_my_id("search_dialog_participants"),
+                                              dialog_id.get_user_id(), query, limit);
+    case DialogType::Chat:
+      return td_->contacts_manager_->search_chat_participants(dialog_id.get_chat_id(), query, limit, force,
+                                                              std::move(promise));
+    case DialogType::Channel:
+      return td_->contacts_manager_->get_channel_participants(
+          dialog_id.get_channel_id(), td_api::make_object<td_api::supergroupMembersFilterSearch>(query), 0, limit,
+          random_id, force, std::move(promise));
+    case DialogType::SecretChat: {
+      promise.set_value(Unit());
+      auto peer_user_id = td_->contacts_manager_->get_secret_chat_user_id(dialog_id.get_secret_chat_id());
+      return search_private_chat_participants(td_->contacts_manager_->get_my_id("search_dialog_participants"),
+                                              peer_user_id, query, limit);
+    }
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      promise.set_error(Status::Error(500, "Wrong chat type"));
+  }
+  return {};
+}
+
+vector<UserId> MessagesManager::get_dialog_administrators(DialogId dialog_id, int left_tries, Promise<Unit> &&promise) {
+  LOG(INFO) << "Receive GetChatAdministrators request in " << dialog_id;
+  if (!have_dialog_force(dialog_id)) {
+    promise.set_error(Status::Error(3, "Chat not found"));
+    return {};
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::SecretChat:
+      promise.set_value(Unit());
+      break;
+    case DialogType::Chat:
+    case DialogType::Channel:
+      return td_->contacts_manager_->get_dialog_administrators(dialog_id, left_tries, std::move(promise));
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      promise.set_error(Status::Error(500, "Wrong chat type"));
+  }
+  return {};
+}
+
+void MessagesManager::export_dialog_invite_link(DialogId dialog_id, Promise<Unit> &&promise) {
+  LOG(INFO) << "Receive ExportDialogInviteLink request for " << dialog_id;
+  if (!have_dialog_force(dialog_id)) {
+    return promise.set_error(Status::Error(3, "Chat not found"));
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      return promise.set_error(Status::Error(3, "Can't invite members to a private chat"));
+    case DialogType::Chat:
+      return td_->contacts_manager_->export_chat_invite_link(dialog_id.get_chat_id(), std::move(promise));
+    case DialogType::Channel:
+      return td_->contacts_manager_->export_channel_invite_link(dialog_id.get_channel_id(), std::move(promise));
+    case DialogType::SecretChat:
+      return promise.set_error(Status::Error(3, "Can't invite members to a secret chat"));
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+}
+
+string MessagesManager::get_dialog_invite_link(DialogId dialog_id) {
+  switch (dialog_id.get_type()) {
+    case DialogType::Chat:
+      return td_->contacts_manager_->get_chat_invite_link(dialog_id.get_chat_id());
+    case DialogType::Channel:
+      return td_->contacts_manager_->get_channel_invite_link(dialog_id.get_channel_id());
+    case DialogType::User:
+    case DialogType::SecretChat:
+    case DialogType::None:
+      return string();
+    default:
+      UNREACHABLE();
+      return string();
+  }
+}
+
+tl_object_ptr<telegram_api::channelAdminLogEventsFilter> MessagesManager::get_channel_admin_log_events_filter(
+    const tl_object_ptr<td_api::chatEventLogFilters> &filters) {
+  if (filters == nullptr) {
+    return nullptr;
+  }
+
+  int32 flags = 0;
+  if (filters->message_edits_) {
+    flags |= telegram_api::channelAdminLogEventsFilter::EDIT_MASK;
+  }
+  if (filters->message_deletions_) {
+    flags |= telegram_api::channelAdminLogEventsFilter::DELETE_MASK;
+  }
+  if (filters->message_pins_) {
+    flags |= telegram_api::channelAdminLogEventsFilter::PINNED_MASK;
+  }
+  if (filters->member_joins_) {
+    flags |= telegram_api::channelAdminLogEventsFilter::JOIN_MASK;
+  }
+  if (filters->member_leaves_) {
+    flags |= telegram_api::channelAdminLogEventsFilter::LEAVE_MASK;
+  }
+  if (filters->member_invites_) {
+    flags |= telegram_api::channelAdminLogEventsFilter::INVITE_MASK;
+  }
+  if (filters->member_promotions_) {
+    flags |= telegram_api::channelAdminLogEventsFilter::PROMOTE_MASK;
+    flags |= telegram_api::channelAdminLogEventsFilter::DEMOTE_MASK;
+  }
+  if (filters->member_restrictions_) {
+    flags |= telegram_api::channelAdminLogEventsFilter::BAN_MASK;
+    flags |= telegram_api::channelAdminLogEventsFilter::UNBAN_MASK;
+    flags |= telegram_api::channelAdminLogEventsFilter::KICK_MASK;
+    flags |= telegram_api::channelAdminLogEventsFilter::UNKICK_MASK;
+  }
+  if (filters->info_changes_) {
+    flags |= telegram_api::channelAdminLogEventsFilter::INFO_MASK;
+  }
+  if (filters->setting_changes_) {
+    flags |= telegram_api::channelAdminLogEventsFilter::SETTINGS_MASK;
+  }
+
+  return make_tl_object<telegram_api::channelAdminLogEventsFilter>(
+      flags, false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/,
+      false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/,
+      false /*ignored*/, false /*ignored*/, false /*ignored*/);
+}
+
+int64 MessagesManager::get_dialog_event_log(DialogId dialog_id, const string &query, int64 from_event_id, int32 limit,
+                                            const tl_object_ptr<td_api::chatEventLogFilters> &filters,
+                                            const vector<UserId> &user_ids, Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    promise.set_error(Status::Error(3, "Method is not available for bots"));
+    return 0;
+  }
+
+  if (!have_dialog_force(dialog_id)) {
+    promise.set_error(Status::Error(3, "Chat not found"));
+    return 0;
+  }
+
+  if (dialog_id.get_type() != DialogType::Channel) {
+    promise.set_error(Status::Error(3, "Chat is not a supergroup chat"));
+    return 0;
+  }
+
+  auto channel_id = dialog_id.get_channel_id();
+  if (!td_->contacts_manager_->have_channel(channel_id)) {
+    promise.set_error(Status::Error(3, "Chat info not found"));
+    return 0;
+  }
+
+  if (!td_->contacts_manager_->get_channel_status(channel_id).is_administrator()) {
+    promise.set_error(Status::Error(3, "Not enough rights to get event log"));
+    return 0;
+  }
+
+  vector<tl_object_ptr<telegram_api::InputUser>> input_users;
+  for (auto user_id : user_ids) {
+    auto input_user = td_->contacts_manager_->get_input_user(user_id);
+    if (input_user == nullptr) {
+      promise.set_error(Status::Error(3, "User not found"));
+      return 0;
+    }
+    input_users.push_back(std::move(input_user));
+  }
+
+  int64 random_id = 0;
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 || chat_events_.find(random_id) != chat_events_.end());
+  chat_events_[random_id];  // reserve place for result
+
+  td_->create_handler<GetChannelAdminLogQuery>(std::move(promise))
+      ->send(channel_id, query, from_event_id, limit, get_channel_admin_log_events_filter(filters),
+             std::move(input_users), random_id);
+
+  return random_id;
+}
+
+tl_object_ptr<td_api::ChatEventAction> MessagesManager::get_chat_event_action_object(
+    tl_object_ptr<telegram_api::ChannelAdminLogEventAction> &&action_ptr) {
+  CHECK(action_ptr != nullptr);
+  switch (action_ptr->get_id()) {
+    case telegram_api::channelAdminLogEventActionParticipantJoin::ID:
+      return make_tl_object<td_api::chatEventMemberJoined>();
+    case telegram_api::channelAdminLogEventActionParticipantLeave::ID:
+      return make_tl_object<td_api::chatEventMemberLeft>();
+    case telegram_api::channelAdminLogEventActionParticipantInvite::ID: {
+      auto action = move_tl_object_as<telegram_api::channelAdminLogEventActionParticipantInvite>(action_ptr);
+      auto member = td_->contacts_manager_->get_dialog_participant(ChannelId(), std::move(action->participant_));
+      return make_tl_object<td_api::chatEventMemberInvited>(
+          td_->contacts_manager_->get_user_id_object(member.user_id, "chatEventMemberInvited"),
+          member.status.get_chat_member_status_object());
+    }
+    case telegram_api::channelAdminLogEventActionParticipantToggleBan::ID: {
+      auto action = move_tl_object_as<telegram_api::channelAdminLogEventActionParticipantToggleBan>(action_ptr);
+      auto old_member =
+          td_->contacts_manager_->get_dialog_participant(ChannelId(), std::move(action->prev_participant_));
+      auto new_member =
+          td_->contacts_manager_->get_dialog_participant(ChannelId(), std::move(action->new_participant_));
+      if (old_member.user_id != new_member.user_id) {
+        LOG(ERROR) << old_member.user_id << " VS " << new_member.user_id;
+        return nullptr;
+      }
+      return make_tl_object<td_api::chatEventMemberRestricted>(
+          td_->contacts_manager_->get_user_id_object(old_member.user_id, "chatEventMemberRestricted"),
+          old_member.status.get_chat_member_status_object(), new_member.status.get_chat_member_status_object());
+    }
+    case telegram_api::channelAdminLogEventActionParticipantToggleAdmin::ID: {
+      auto action = move_tl_object_as<telegram_api::channelAdminLogEventActionParticipantToggleAdmin>(action_ptr);
+      auto old_member =
+          td_->contacts_manager_->get_dialog_participant(ChannelId(), std::move(action->prev_participant_));
+      auto new_member =
+          td_->contacts_manager_->get_dialog_participant(ChannelId(), std::move(action->new_participant_));
+      if (old_member.user_id != new_member.user_id) {
+        LOG(ERROR) << old_member.user_id << " VS " << new_member.user_id;
+        return nullptr;
+      }
+      return make_tl_object<td_api::chatEventMemberPromoted>(
+          td_->contacts_manager_->get_user_id_object(old_member.user_id, "chatEventMemberPromoted"),
+          old_member.status.get_chat_member_status_object(), new_member.status.get_chat_member_status_object());
+    }
+    case telegram_api::channelAdminLogEventActionChangeTitle::ID: {
+      auto action = move_tl_object_as<telegram_api::channelAdminLogEventActionChangeTitle>(action_ptr);
+      return make_tl_object<td_api::chatEventTitleChanged>(std::move(action->prev_value_),
+                                                           std::move(action->new_value_));
+    }
+    case telegram_api::channelAdminLogEventActionChangeAbout::ID: {
+      auto action = move_tl_object_as<telegram_api::channelAdminLogEventActionChangeAbout>(action_ptr);
+      return make_tl_object<td_api::chatEventDescriptionChanged>(std::move(action->prev_value_),
+                                                                 std::move(action->new_value_));
+    }
+    case telegram_api::channelAdminLogEventActionChangeUsername::ID: {
+      auto action = move_tl_object_as<telegram_api::channelAdminLogEventActionChangeUsername>(action_ptr);
+      return make_tl_object<td_api::chatEventUsernameChanged>(std::move(action->prev_value_),
+                                                              std::move(action->new_value_));
+    }
+    case telegram_api::channelAdminLogEventActionChangePhoto::ID: {
+      auto action = move_tl_object_as<telegram_api::channelAdminLogEventActionChangePhoto>(action_ptr);
+      auto file_manager = td_->file_manager_.get();
+      auto old_photo = td::get_dialog_photo(file_manager, std::move(action->prev_photo_));
+      auto new_photo = td::get_dialog_photo(file_manager, std::move(action->new_photo_));
+      return make_tl_object<td_api::chatEventPhotoChanged>(get_chat_photo_object(file_manager, &old_photo),
+                                                           get_chat_photo_object(file_manager, &new_photo));
+    }
+    case telegram_api::channelAdminLogEventActionToggleInvites::ID: {
+      auto action = move_tl_object_as<telegram_api::channelAdminLogEventActionToggleInvites>(action_ptr);
+      return make_tl_object<td_api::chatEventInvitesToggled>(action->new_value_);
+    }
+    case telegram_api::channelAdminLogEventActionToggleSignatures::ID: {
+      auto action = move_tl_object_as<telegram_api::channelAdminLogEventActionToggleSignatures>(action_ptr);
+      return make_tl_object<td_api::chatEventSignMessagesToggled>(action->new_value_);
+    }
+    case telegram_api::channelAdminLogEventActionUpdatePinned::ID: {
+      auto action = move_tl_object_as<telegram_api::channelAdminLogEventActionUpdatePinned>(action_ptr);
+      auto message = create_message(
+          parse_telegram_api_message(std::move(action->message_), "channelAdminLogEventActionUpdatePinned"), true);
+      if (message.second == nullptr) {
+        return make_tl_object<td_api::chatEventMessageUnpinned>();
+      }
+      return make_tl_object<td_api::chatEventMessagePinned>(get_message_object(message.first, message.second.get()));
+    }
+    case telegram_api::channelAdminLogEventActionEditMessage::ID: {
+      auto action = move_tl_object_as<telegram_api::channelAdminLogEventActionEditMessage>(action_ptr);
+      auto old_message = create_message(
+          parse_telegram_api_message(std::move(action->prev_message_), "prev channelAdminLogEventActionEditMessage"),
+          true);
+      auto new_message = create_message(
+          parse_telegram_api_message(std::move(action->new_message_), "new channelAdminLogEventActionEditMessage"),
+          true);
+      if (old_message.second == nullptr || new_message.second == nullptr || old_message.first != new_message.first) {
+        LOG(ERROR) << "Failed to get edited message";
+        return nullptr;
+      }
+      return make_tl_object<td_api::chatEventMessageEdited>(
+          get_message_object(old_message.first, old_message.second.get()),
+          get_message_object(new_message.first, new_message.second.get()));
+    }
+    case telegram_api::channelAdminLogEventActionDeleteMessage::ID: {
+      auto action = move_tl_object_as<telegram_api::channelAdminLogEventActionDeleteMessage>(action_ptr);
+      auto message = create_message(
+          parse_telegram_api_message(std::move(action->message_), "channelAdminLogEventActionDeleteMessage"), true);
+      if (message.second == nullptr) {
+        LOG(ERROR) << "Failed to get deleted message";
+        return nullptr;
+      }
+      return make_tl_object<td_api::chatEventMessageDeleted>(get_message_object(message.first, message.second.get()));
+    }
+    case telegram_api::channelAdminLogEventActionChangeStickerSet::ID: {
+      auto action = move_tl_object_as<telegram_api::channelAdminLogEventActionChangeStickerSet>(action_ptr);
+      auto old_sticker_set_id = td_->stickers_manager_->add_sticker_set(std::move(action->prev_stickerset_));
+      auto new_sticker_set_id = td_->stickers_manager_->add_sticker_set(std::move(action->new_stickerset_));
+      return make_tl_object<td_api::chatEventStickerSetChanged>(old_sticker_set_id, new_sticker_set_id);
+    }
+    case telegram_api::channelAdminLogEventActionTogglePreHistoryHidden::ID: {
+      auto action = move_tl_object_as<telegram_api::channelAdminLogEventActionTogglePreHistoryHidden>(action_ptr);
+      return make_tl_object<td_api::chatEventIsAllHistoryAvailableToggled>(!action->new_value_);
+    }
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+void MessagesManager::on_get_event_log(int64 random_id,
+                                       tl_object_ptr<telegram_api::channels_adminLogResults> &&events) {
+  auto it = chat_events_.find(random_id);
+  CHECK(it != chat_events_.end());
+  auto &result = it->second;
+  CHECK(result == nullptr);
+
+  if (events == nullptr) {
+    chat_events_.erase(it);
+    return;
+  }
+
+  LOG(INFO) << "Receive " << to_string(events);
+
+  td_->contacts_manager_->on_get_users(std::move(events->users_));
+  td_->contacts_manager_->on_get_chats(std::move(events->chats_));
+
+  result = make_tl_object<td_api::chatEvents>();
+  result->events_.reserve(events->events_.size());
+  for (auto &event : events->events_) {
+    if (event->date_ <= 0) {
+      LOG(ERROR) << "Receive wrong event date = " << event->date_;
+      event->date_ = 0;
+    }
+
+    UserId user_id(event->user_id_);
+    if (!user_id.is_valid()) {
+      LOG(ERROR) << "Receive invalid " << user_id;
+      continue;
+    }
+    LOG_IF(ERROR, !td_->contacts_manager_->have_user(user_id)) << "Have no info about " << user_id;
+
+    auto action = get_chat_event_action_object(std::move(event->action_));
+    if (action == nullptr) {
+      continue;
+    }
+    result->events_.push_back(make_tl_object<td_api::chatEvent>(
+        event->id_, event->date_, td_->contacts_manager_->get_user_id_object(user_id, "chatEvent"), std::move(action)));
+  }
+}
+
+tl_object_ptr<td_api::chatEvents> MessagesManager::get_chat_events_object(int64 random_id) {
+  auto it = chat_events_.find(random_id);
+  CHECK(it != chat_events_.end());
+  auto result = std::move(it->second);
+  chat_events_.erase(it);
+  return result;
+}
+
+unique_ptr<MessagesManager::Message> *MessagesManager::find_message(unique_ptr<Message> *v, MessageId message_id) {
+  return const_cast<unique_ptr<Message> *>(find_message(static_cast<const unique_ptr<Message> *>(v), message_id));
+}
+
+const unique_ptr<MessagesManager::Message> *MessagesManager::find_message(const unique_ptr<Message> *v,
+                                                                          MessageId message_id) {
+  LOG(DEBUG) << "Searching for " << message_id << " in " << static_cast<const void *>(v->get());
+  while (*v != nullptr) {
+    //    LOG(DEBUG) << "Pass " << (*v)->message_id;
+    if ((*v)->message_id.get() < message_id.get()) {
+      //      LOG(DEBUG) << "Go right";
+      v = &(*v)->right;
+    } else if ((*v)->message_id.get() > message_id.get()) {
+      //      LOG(DEBUG) << "Go left";
+      v = &(*v)->left;
+    } else {
+      LOG(DEBUG) << "Message found";
+      break;
+    }
+  }
+  return v;
+}
+
+MessagesManager::Message *MessagesManager::get_message(Dialog *d, MessageId message_id) {
+  return const_cast<Message *>(get_message(static_cast<const Dialog *>(d), message_id));
+}
+
+const MessagesManager::Message *MessagesManager::get_message(const Dialog *d, MessageId message_id) {
+  if (!message_id.is_valid()) {
+    return nullptr;
+  }
+
+  CHECK(d != nullptr);
+  LOG(DEBUG) << "Search for " << message_id << " in " << d->dialog_id;
+  auto result = find_message(&d->messages, message_id)->get();
+  if (result != nullptr) {
+    result->last_access_date = G()->unix_time_cached();
+  }
+  return result;
+}
+
+MessagesManager::Message *MessagesManager::get_message_force(Dialog *d, MessageId message_id) {
+  if (!message_id.is_valid()) {
+    return nullptr;
+  }
+
+  auto result = get_message(d, message_id);
+  if (result != nullptr) {
+    return result;
+  }
+
+  if (!G()->parameters().use_message_db || message_id.is_yet_unsent()) {
+    return nullptr;
+  }
+
+  if (d->deleted_message_ids.count(message_id)) {
+    return nullptr;
+  }
+
+  LOG(INFO) << "Try to load " << FullMessageId{d->dialog_id, message_id} << " from database";
+  auto r_value = G()->td_db()->get_messages_db_sync()->get_message({d->dialog_id, message_id});
+  if (r_value.is_error()) {
+    return nullptr;
+  }
+  return on_get_message_from_database(d->dialog_id, d, r_value.ok());
+}
+
+MessagesManager::Message *MessagesManager::on_get_message_from_database(DialogId dialog_id, Dialog *d,
+                                                                        const BufferSlice &value) {
+  if (value.empty()) {
+    return nullptr;
+  }
+
+  auto m = make_unique<Message>();
+  log_event_parse(*m, value.as_slice()).ensure();
+
+  if (d == nullptr) {
+    LOG(ERROR) << "Can't find " << dialog_id << ", but have a message from it";
+    if (!dialog_id.is_valid()) {
+      LOG(ERROR) << "Got message in invalid " << dialog_id;
+      return nullptr;
+    }
+
+    get_messages_from_server({FullMessageId{dialog_id, m->message_id}}, Auto());
+
+    force_create_dialog(dialog_id, "on_get_message_from_database");
+    d = get_dialog_force(dialog_id);
+    CHECK(d != nullptr);
+  }
+
+  if (!have_input_peer(d->dialog_id, AccessRights::Read)) {
+    return nullptr;
+  }
+
+  auto old_message = get_message(d, m->message_id);
+  if (old_message != nullptr) {
+    // data in the database is always outdated, so return a message from the memory
+    return old_message;
+  }
+
+  Dependencies dependencies;
+  add_message_dependencies(dependencies, d->dialog_id, m.get());
+  resolve_dependencies_force(dependencies);
+
+  m->have_next = false;
+  m->have_previous = false;
+  m->from_database = true;
+  bool need_update = false;
+  bool need_update_dialog_pos = false;
+  auto result = add_message_to_dialog(d, std::move(m), false, &need_update, &need_update_dialog_pos,
+                                      "on_get_message_from_database");
+  if (need_update_dialog_pos) {
+    LOG(ERROR) << "Need update dialog pos after load " << (result == nullptr ? MessageId() : result->message_id)
+               << " in " << d->dialog_id << " from database";
+    send_update_chat_last_message(d, "on_get_message_from_database");
+  }
+  return result;
+}
+
+NotificationSettings MessagesManager::get_notification_settings(
+    tl_object_ptr<telegram_api::PeerNotifySettings> &&notification_settings) {
+  int32 constructor_id = notification_settings->get_id();
+  if (constructor_id == telegram_api::peerNotifySettingsEmpty::ID) {
+    LOG(ERROR) << "Empty notify settings received";
+    return {};
+  }
+  CHECK(constructor_id == telegram_api::peerNotifySettings::ID);
+  auto settings = static_cast<const telegram_api::peerNotifySettings *>(notification_settings.get());
+  auto mute_until = (settings->mute_until_ <= G()->unix_time() ? 0 : settings->mute_until_);
+  return {mute_until, settings->sound_, (settings->flags_ & telegram_api::peerNotifySettings::SHOW_PREVIEWS_MASK) != 0,
+          (settings->flags_ & telegram_api::peerNotifySettings::SILENT_MASK) != 0};
+}
+
+unique_ptr<MessageContent> MessagesManager::get_secret_message_document(
+    tl_object_ptr<telegram_api::encryptedFile> file,
+    tl_object_ptr<secret_api::decryptedMessageMediaDocument> &&document,
+    vector<tl_object_ptr<telegram_api::DocumentAttribute>> &&attributes, DialogId owner_dialog_id,
+    FormattedText &&caption, bool is_opened) const {
+  return get_message_document(td_->documents_manager_->on_get_document(
+                                  {std::move(file), std::move(document), std::move(attributes)}, owner_dialog_id),
+                              std::move(caption), is_opened);
+}
+
+unique_ptr<MessageContent> MessagesManager::get_message_document(tl_object_ptr<telegram_api::document> &&document,
+                                                                 DialogId owner_dialog_id, FormattedText &&caption,
+                                                                 bool is_opened,
+                                                                 MultiPromiseActor *load_data_multipromise_ptr) const {
+  return get_message_document(
+      td_->documents_manager_->on_get_document(std::move(document), owner_dialog_id, load_data_multipromise_ptr),
+      std::move(caption), is_opened);
+}
+
+unique_ptr<MessageContent> MessagesManager::get_message_document(
+    std::pair<DocumentsManager::DocumentType, FileId> &&parsed_document, FormattedText &&caption,
+    bool is_opened) const {
+  auto document_type = parsed_document.first;
+  auto file_id = parsed_document.second;
+  if (document_type != DocumentsManager::DocumentType::Unknown) {
+    CHECK(file_id.is_valid());
+  }
+  switch (document_type) {
+    case DocumentsManager::DocumentType::Animation:
+      return make_unique<MessageAnimation>(file_id, std::move(caption));
+    case DocumentsManager::DocumentType::Audio:
+      return make_unique<MessageAudio>(file_id, std::move(caption));
+    case DocumentsManager::DocumentType::General:
+      return make_unique<MessageDocument>(file_id, std::move(caption));
+    case DocumentsManager::DocumentType::Sticker:
+      return make_unique<MessageSticker>(file_id);
+    case DocumentsManager::DocumentType::Unknown:
+      return make_unique<MessageUnsupported>();
+    case DocumentsManager::DocumentType::Video:
+      return make_unique<MessageVideo>(file_id, std::move(caption));
+    case DocumentsManager::DocumentType::VideoNote:
+      return make_unique<MessageVideoNote>(file_id, is_opened);
+    case DocumentsManager::DocumentType::VoiceNote:
+      return make_unique<MessageVoiceNote>(file_id, std::move(caption), is_opened);
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+unique_ptr<MessagePhoto> MessagesManager::get_message_photo(tl_object_ptr<telegram_api::photo> &&photo,
+                                                            DialogId owner_dialog_id, FormattedText &&caption) const {
+  auto m = make_unique<MessagePhoto>();
+
+  m->photo = get_photo(td_->file_manager_.get(), std::move(photo), owner_dialog_id);
+  m->caption = std::move(caption);
+
+  return m;
+}
+
+FormattedText MessagesManager::get_secret_media_caption(string &&message_text, string &&message_caption) {
+  FormattedText caption;
+  if (message_text.empty()) {
+    caption.text = std::move(message_caption);
+  } else if (message_caption.empty()) {
+    caption.text = std::move(message_text);
+  } else {
+    caption.text = message_text + "\n\n" + message_caption;
+  }
+
+  caption.entities = find_entities(caption.text, false);
+  return caption;
+}
+
+FormattedText MessagesManager::get_message_text(string message_text,
+                                                vector<tl_object_ptr<telegram_api::MessageEntity>> &&server_entities,
+                                                int32 send_date) const {
+  auto entities = get_message_entities(td_->contacts_manager_.get(), std::move(server_entities), "get_message_text");
+  auto status = fix_formatted_text(message_text, entities, true, true, true, false);
+  if (status.is_error()) {
+    if (send_date == 0 || send_date > 1497000000) {  // approximate fix date
+      LOG(ERROR) << "Receive error " << status << " while parsing message content \"" << message_text << "\" sent at "
+                 << send_date << " with entities " << format::as_array(entities);
+    }
+    if (!clean_input_string(message_text)) {
+      message_text.clear();
+    }
+    entities.clear();
+  }
+  return FormattedText{std::move(message_text), std::move(entities)};
+}
+
+template <class ToT, class FromT>
+static tl_object_ptr<ToT> secret_to_telegram(FromT &from);
+
+// fileLocationUnavailable#7c596b46 volume_id:long local_id:int secret:long = FileLocation;
+static auto secret_to_telegram(secret_api::fileLocationUnavailable &file_location) {
+  return make_tl_object<telegram_api::fileLocationUnavailable>(file_location.volume_id_, file_location.local_id_,
+                                                               file_location.secret_);
+}
+
+// fileLocation#53d69076 dc_id:int volume_id:long local_id:int secret:long = FileLocation;
+static auto secret_to_telegram(secret_api::fileLocation &file_location) {
+  return make_tl_object<telegram_api::fileLocation>(file_location.dc_id_, file_location.volume_id_,
+                                                    file_location.local_id_, file_location.secret_);
+}
+
+// photoSizeEmpty#e17e23c type:string = PhotoSize;
+static auto secret_to_telegram(secret_api::photoSizeEmpty &empty) {
+  if (!clean_input_string(empty.type_)) {
+    empty.type_.clear();
+  }
+  return make_tl_object<telegram_api::photoSizeEmpty>(empty.type_);
+}
+
+// photoSize#77bfb61b type:string location:FileLocation w:int h:int size:int = PhotoSize;
+static auto secret_to_telegram(secret_api::photoSize &photo_size) {
+  if (!clean_input_string(photo_size.type_)) {
+    photo_size.type_.clear();
+  }
+  return make_tl_object<telegram_api::photoSize>(photo_size.type_,
+                                                 secret_to_telegram<telegram_api::FileLocation>(*photo_size.location_),
+                                                 photo_size.w_, photo_size.h_, photo_size.size_);
+}
+
+// photoCachedSize#e9a734fa type:string location:FileLocation w:int h:int bytes:bytes = PhotoSize;
+static auto secret_to_telegram(secret_api::photoCachedSize &photo_size) {
+  if (!clean_input_string(photo_size.type_)) {
+    photo_size.type_.clear();
+  }
+  return make_tl_object<telegram_api::photoCachedSize>(
+      photo_size.type_, secret_to_telegram<telegram_api::FileLocation>(*photo_size.location_), photo_size.w_,
+      photo_size.h_, photo_size.bytes_.clone());
+}
+
+// documentAttributeImageSize #6c37c15c w:int h:int = DocumentAttribute;
+static auto secret_to_telegram(secret_api::documentAttributeImageSize &image_size) {
+  return make_tl_object<telegram_api::documentAttributeImageSize>(image_size.w_, image_size.h_);
+}
+
+// documentAttributeAnimated #11b58939 = DocumentAttribute;
+static auto secret_to_telegram(secret_api::documentAttributeAnimated &animated) {
+  return make_tl_object<telegram_api::documentAttributeAnimated>();
+}
+
+// documentAttributeSticker23 #fb0a5727 = DocumentAttribute;
+static auto secret_to_telegram(secret_api::documentAttributeSticker23 &sticker) {
+  return make_tl_object<telegram_api::documentAttributeSticker>(
+      0, false /*ignored*/, "", make_tl_object<telegram_api::inputStickerSetEmpty>(), nullptr);
+}
+static auto secret_to_telegram(secret_api::inputStickerSetEmpty &sticker_set) {
+  return make_tl_object<telegram_api::inputStickerSetEmpty>();
+}
+static auto secret_to_telegram(secret_api::inputStickerSetShortName &sticker_set) {
+  if (!clean_input_string(sticker_set.short_name_)) {
+    sticker_set.short_name_.clear();
+  }
+  return make_tl_object<telegram_api::inputStickerSetShortName>(sticker_set.short_name_);
+}
+
+// documentAttributeSticker #3a556302 alt:string stickerset:InputStickerSet = DocumentAttribute;
+static auto secret_to_telegram(secret_api::documentAttributeSticker &sticker) {
+  if (!clean_input_string(sticker.alt_)) {
+    sticker.alt_.clear();
+  }
+  return make_tl_object<telegram_api::documentAttributeSticker>(
+      0, false /*ignored*/, sticker.alt_, secret_to_telegram<telegram_api::InputStickerSet>(*sticker.stickerset_),
+      nullptr);
+}
+
+// documentAttributeVideo #5910cccb duration:int w:int h:int = DocumentAttribute;
+static auto secret_to_telegram(secret_api::documentAttributeVideo &video) {
+  return make_tl_object<telegram_api::documentAttributeVideo>(0, false /*ignored*/, false /*ignored*/, video.duration_,
+                                                              video.w_, video.h_);
+}
+
+// documentAttributeFilename #15590068 file_name:string = DocumentAttribute;
+static auto secret_to_telegram(secret_api::documentAttributeFilename &filename) {
+  if (!clean_input_string(filename.file_name_)) {
+    filename.file_name_.clear();
+  }
+  return make_tl_object<telegram_api::documentAttributeFilename>(filename.file_name_);
+}
+
+// documentAttributeVideo66#ef02ce6 flags:# round_message:flags.0?true duration:int w:int h:int = DocumentAttribute;
+static auto secret_to_telegram(secret_api::documentAttributeVideo66 &video) {
+  return make_tl_object<telegram_api::documentAttributeVideo>(
+      (video.flags_ & secret_api::documentAttributeVideo66::ROUND_MESSAGE_MASK) != 0
+          ? telegram_api::documentAttributeVideo::ROUND_MESSAGE_MASK
+          : 0,
+      video.round_message_, false, video.duration_, video.w_, video.h_);
+}
+
+static auto telegram_documentAttributeAudio(bool is_voice_note, int duration, string title, string performer,
+                                            BufferSlice waveform) {
+  if (!clean_input_string(title)) {
+    title.clear();
+  }
+  if (!clean_input_string(performer)) {
+    performer.clear();
+  }
+
+  int32 flags = 0;
+  if (is_voice_note) {
+    flags |= telegram_api::documentAttributeAudio::VOICE_MASK;
+  }
+  if (!title.empty()) {
+    flags |= telegram_api::documentAttributeAudio::TITLE_MASK;
+  }
+  if (!performer.empty()) {
+    flags |= telegram_api::documentAttributeAudio::PERFORMER_MASK;
+  }
+  if (waveform.size()) {
+    flags |= telegram_api::documentAttributeAudio::WAVEFORM_MASK;
+  }
+  return make_tl_object<telegram_api::documentAttributeAudio>(flags, is_voice_note, duration, std::move(title),
+                                                              std::move(performer), std::move(waveform));
+}
+
+// documentAttributeAudio23 #51448e5 duration:int = DocumentAttribute;
+static auto secret_to_telegram(secret_api::documentAttributeAudio23 &audio) {
+  return telegram_documentAttributeAudio(false, audio.duration_, "", "", Auto());
+}
+// documentAttributeAudio45 #ded218e0 duration:int title:string performer:string = DocumentAttribute;
+static auto secret_to_telegram(secret_api::documentAttributeAudio45 &audio) {
+  return telegram_documentAttributeAudio(false, audio.duration_, audio.title_, audio.performer_, Auto());
+}
+
+// documentAttributeAudio#9852f9c6 flags:# voice:flags.10?true duration:int title:flags.0?string
+//    performer:flags.1?string waveform:flags.2?bytes = DocumentAttribute;
+static auto secret_to_telegram(secret_api::documentAttributeAudio &audio) {
+  return telegram_documentAttributeAudio((audio.flags_ & secret_api::documentAttributeAudio::VOICE_MASK) != 0,
+                                         audio.duration_, audio.title_, audio.performer_, audio.waveform_.clone());
+}
+
+static auto secret_to_telegram(std::vector<tl_object_ptr<secret_api::DocumentAttribute>> &attributes) {
+  std::vector<tl_object_ptr<telegram_api::DocumentAttribute>> res;
+  for (auto &attribute : attributes) {
+    auto telegram_attribute = secret_to_telegram<telegram_api::DocumentAttribute>(*attribute);
+    if (telegram_attribute) {
+      res.push_back(std::move(telegram_attribute));
+    }
+  }
+  return res;
+}
+
+// decryptedMessageMediaExternalDocument#fa95b0dd id:long access_hash:long date:int mime_type:string size:int
+// thumb:PhotoSize dc_id:int attributes:Vector<DocumentAttribute> = DecryptedMessageMedia;
+static auto secret_to_telegram_document(secret_api::decryptedMessageMediaExternalDocument &from) {
+  if (!clean_input_string(from.mime_type_)) {
+    from.mime_type_.clear();
+  }
+  return make_tl_object<telegram_api::document>(from.id_, from.access_hash_, from.date_, from.mime_type_, from.size_,
+                                                secret_to_telegram<telegram_api::PhotoSize>(*from.thumb_), from.dc_id_,
+                                                0, secret_to_telegram(from.attributes_));
+}
+
+template <class ToT, class FromT>
+static tl_object_ptr<ToT> secret_to_telegram(FromT &from) {
+  tl_object_ptr<ToT> res;
+  downcast_call(from, [&](auto &p) { res = secret_to_telegram(p); });
+  return res;
+}
+
+Photo MessagesManager::get_web_document_photo(tl_object_ptr<telegram_api::WebDocument> web_document,
+                                              DialogId owner_dialog_id) const {
+  PhotoSize s =
+      get_web_document_photo_size(td_->file_manager_.get(), FileType::Photo, owner_dialog_id, std::move(web_document));
+  Photo photo;
+  if (!s.file_id.is_valid()) {
+    photo.id = -2;
+  } else {
+    photo.id = 0;
+    photo.photos.push_back(s);
+  }
+  return photo;
+}
+
+unique_ptr<MessageContent> MessagesManager::get_secret_message_content(
+    string message_text, tl_object_ptr<telegram_api::encryptedFile> file,
+    tl_object_ptr<secret_api::DecryptedMessageMedia> &&media,
+    vector<tl_object_ptr<secret_api::MessageEntity>> &&secret_entities, DialogId owner_dialog_id,
+    MultiPromiseActor &load_data_multipromise) const {
+  auto entities = get_message_entities(std::move(secret_entities));
+  auto status = fix_formatted_text(message_text, entities, true, false, true, false);
+  if (status.is_error()) {
+    LOG(WARNING) << "Receive error " << status << " while parsing secret message \"" << message_text
+                 << "\" with entities " << format::as_array(entities);
+    if (!clean_input_string(message_text)) {
+      message_text.clear();
+    }
+    entities.clear();
+  }
+
+  if (media == nullptr) {
+    return make_unique<MessageText>(FormattedText{std::move(message_text), std::move(entities)}, WebPageId());
+  }
+
+  int32 constructor_id = media->get_id();
+  if (message_text.size()) {
+    if (constructor_id != secret_api::decryptedMessageMediaEmpty::ID) {
+      LOG(INFO) << "Receive non-empty message text and media";
+    } else {
+      return make_unique<MessageText>(FormattedText{std::move(message_text), std::move(entities)}, WebPageId());
+    }
+  }
+
+  // support of old layer and old constructions
+  switch (constructor_id) {
+    case secret_api::decryptedMessageMediaVideo::ID: {
+      auto video = move_tl_object_as<secret_api::decryptedMessageMediaVideo>(media);
+      std::vector<tl_object_ptr<secret_api::DocumentAttribute>> attributes;
+      attributes.emplace_back(
+          make_tl_object<secret_api::documentAttributeVideo>(video->duration_, video->w_, video->h_));
+      media = make_tl_object<secret_api::decryptedMessageMediaDocument>(
+          std::move(video->thumb_), video->thumb_w_, video->thumb_h_, video->mime_type_, video->size_,
+          std::move(video->key_), std::move(video->iv_), std::move(attributes), std::move(video->caption_));
+
+      constructor_id = secret_api::decryptedMessageMediaDocument::ID;
+      break;
+    }
+  }
+
+  bool is_media_empty = false;
+  switch (constructor_id) {
+    case secret_api::decryptedMessageMediaEmpty::ID:
+      LOG(ERROR) << "Receive empty message text and media";
+      is_media_empty = true;
+      break;
+    case secret_api::decryptedMessageMediaGeoPoint::ID: {
+      auto message_geo_point = move_tl_object_as<secret_api::decryptedMessageMediaGeoPoint>(media);
+
+      auto m = make_unique<MessageLocation>(Location(std::move(message_geo_point)));
+      if (m->location.empty()) {
+        is_media_empty = true;
+        break;
+      }
+
+      return std::move(m);
+    }
+    case secret_api::decryptedMessageMediaVenue::ID: {
+      auto message_venue = move_tl_object_as<secret_api::decryptedMessageMediaVenue>(media);
+
+      if (!clean_input_string(message_venue->title_)) {
+        message_venue->title_.clear();
+      }
+      if (!clean_input_string(message_venue->address_)) {
+        message_venue->address_.clear();
+      }
+      if (!clean_input_string(message_venue->provider_)) {
+        message_venue->provider_.clear();
+      }
+      if (!clean_input_string(message_venue->venue_id_)) {
+        message_venue->venue_id_.clear();
+      }
+
+      auto m =
+          make_unique<MessageVenue>(Venue(Location(message_venue->lat_, message_venue->long_),
+                                          std::move(message_venue->title_), std::move(message_venue->address_),
+                                          std::move(message_venue->provider_), std::move(message_venue->venue_id_)));
+      if (m->venue.empty()) {
+        is_media_empty = true;
+        break;
+      }
+
+      return std::move(m);
+    }
+    case secret_api::decryptedMessageMediaContact::ID: {
+      auto message_contact = move_tl_object_as<secret_api::decryptedMessageMediaContact>(media);
+      if (!clean_input_string(message_contact->phone_number_)) {
+        message_contact->phone_number_.clear();
+      }
+      if (!clean_input_string(message_contact->first_name_)) {
+        message_contact->first_name_.clear();
+      }
+      if (!clean_input_string(message_contact->last_name_)) {
+        message_contact->last_name_.clear();
+      }
+      return make_unique<MessageContact>(Contact(message_contact->phone_number_, message_contact->first_name_,
+                                                 message_contact->last_name_, message_contact->user_id_));
+    }
+    case secret_api::decryptedMessageMediaWebPage::ID: {
+      auto media_web_page = move_tl_object_as<secret_api::decryptedMessageMediaWebPage>(media);
+      if (!clean_input_string(media_web_page->url_)) {
+        media_web_page->url_.clear();
+      }
+      auto r_http_url = parse_url(media_web_page->url_);
+      if (r_http_url.is_error()) {
+        is_media_empty = true;
+        break;
+      }
+      auto url = r_http_url.ok().get_url();
+
+      auto web_page_id = td_->web_pages_manager_->get_web_page_by_url(url, load_data_multipromise.get_promise());
+      auto result = make_unique<MessageText>(FormattedText{std::move(message_text), std::move(entities)}, web_page_id);
+      if (!result->web_page_id.is_valid()) {
+        load_data_multipromise.add_promise(
+            PromiseCreator::lambda([td = td_, url, &web_page_id = result->web_page_id](Result<Unit> result) {
+              if (result.is_ok()) {
+                web_page_id = td->web_pages_manager_->get_web_page_by_url(url);
+              }
+            }));
+      }
+      return std::move(result);
+    }
+    case secret_api::decryptedMessageMediaExternalDocument::ID: {
+      auto external_document = move_tl_object_as<secret_api::decryptedMessageMediaExternalDocument>(media);
+      auto document = secret_to_telegram_document(*external_document);
+      return get_message_document(std::move(document), owner_dialog_id,
+                                  FormattedText{std::move(message_text), std::move(entities)}, false,
+                                  &load_data_multipromise);
+    }
+  }
+  if (file == nullptr && !is_media_empty) {
+    LOG(ERROR) << "Received secret message with media, but without a file";
+    is_media_empty = true;
+  }
+  if (is_media_empty) {
+    return make_unique<MessageText>(FormattedText{std::move(message_text), std::move(entities)}, WebPageId());
+  }
+  switch (constructor_id) {
+    case secret_api::decryptedMessageMediaPhoto::ID: {
+      auto message_photo = move_tl_object_as<secret_api::decryptedMessageMediaPhoto>(media);
+      if (!clean_input_string(message_photo->caption_)) {
+        message_photo->caption_.clear();
+      }
+      return make_unique<MessagePhoto>(
+          get_photo(td_->file_manager_.get(), std::move(file), std::move(message_photo), owner_dialog_id),
+          get_secret_media_caption(std::move(message_text), std::move(message_photo->caption_)));
+    }
+    case secret_api::decryptedMessageMediaDocument::ID: {
+      auto message_document = move_tl_object_as<secret_api::decryptedMessageMediaDocument>(media);
+      if (!clean_input_string(message_document->caption_)) {
+        message_document->caption_.clear();
+      }
+      if (!clean_input_string(message_document->mime_type_)) {
+        message_document->mime_type_.clear();
+      }
+      auto attributes = secret_to_telegram(message_document->attributes_);
+      message_document->attributes_.clear();
+      return get_secret_message_document(
+          std::move(file), std::move(message_document), std::move(attributes), owner_dialog_id,
+          get_secret_media_caption(std::move(message_text), std::move(message_document->caption_)), false);
+    }
+    default:
+      LOG(ERROR) << "Unsupported: " << to_string(media);
+      return make_unique<MessageUnsupported>();
+  }
+}
+
+unique_ptr<MessageContent> MessagesManager::get_message_content(FormattedText message,
+                                                                tl_object_ptr<telegram_api::MessageMedia> &&media,
+                                                                DialogId owner_dialog_id, bool is_content_read,
+                                                                UserId via_bot_user_id, int32 *ttl) const {
+  if (media == nullptr) {
+    return make_unique<MessageText>(std::move(message), WebPageId());
+  }
+
+  int32 constructor_id = media->get_id();
+  if (message.text.size()) {
+    if (constructor_id != telegram_api::messageMediaEmpty::ID) {
+      LOG(INFO) << "Receive non-empty message text and media for message from " << owner_dialog_id;
+    } else {
+      return make_unique<MessageText>(std::move(message), WebPageId());
+    }
+  }
+  switch (constructor_id) {
+    case telegram_api::messageMediaEmpty::ID:
+      LOG(ERROR) << "Receive empty message text and media for message from " << owner_dialog_id;
+      return make_unique<MessageText>(std::move(message), WebPageId());
+    case telegram_api::messageMediaPhoto::ID: {
+      auto message_photo = move_tl_object_as<telegram_api::messageMediaPhoto>(media);
+      if ((message_photo->flags_ & telegram_api::messageMediaPhoto::PHOTO_MASK) == 0) {
+        if ((message_photo->flags_ & telegram_api::messageMediaPhoto::TTL_SECONDS_MASK) == 0) {
+          LOG(ERROR) << "Receive messageMediaPhoto without photo and TTL: " << oneline(to_string(message_photo));
+          break;
+        }
+
+        return make_unique<MessageExpiredPhoto>();
+      }
+
+      auto photo_ptr = std::move(message_photo->photo_);
+      int32 photo_id = photo_ptr->get_id();
+      if (photo_id == telegram_api::photoEmpty::ID) {
+        return make_unique<MessageExpiredPhoto>();
+      }
+      CHECK(photo_id == telegram_api::photo::ID);
+
+      if (ttl != nullptr && (message_photo->flags_ & telegram_api::messageMediaPhoto::TTL_SECONDS_MASK) != 0) {
+        *ttl = message_photo->ttl_seconds_;
+      }
+      return get_message_photo(move_tl_object_as<telegram_api::photo>(photo_ptr), owner_dialog_id, std::move(message));
+    }
+    case telegram_api::messageMediaGeo::ID: {
+      auto message_geo_point = move_tl_object_as<telegram_api::messageMediaGeo>(media);
+
+      auto m = make_unique<MessageLocation>(Location(std::move(message_geo_point->geo_)));
+      if (m->location.empty()) {
+        break;
+      }
+
+      return std::move(m);
+    }
+    case telegram_api::messageMediaGeoLive::ID: {
+      auto message_geo_point_live = move_tl_object_as<telegram_api::messageMediaGeoLive>(media);
+      int32 period = message_geo_point_live->period_;
+      auto location = Location(std::move(message_geo_point_live->geo_));
+      if (location.empty()) {
+        break;
+      }
+
+      if (period <= 0) {
+        LOG(ERROR) << "Receive wrong live location period = " << period;
+        return make_unique<MessageLocation>(std::move(location));
+      }
+      return make_unique<MessageLiveLocation>(std::move(location), period);
+    }
+    case telegram_api::messageMediaVenue::ID: {
+      auto message_venue = move_tl_object_as<telegram_api::messageMediaVenue>(media);
+
+      auto m = make_unique<MessageVenue>(Venue(message_venue->geo_, std::move(message_venue->title_),
+                                               std::move(message_venue->address_), std::move(message_venue->provider_),
+                                               std::move(message_venue->venue_id_)));
+      if (m->venue.empty()) {
+        break;
+      }
+
+      return std::move(m);
+    }
+    case telegram_api::messageMediaContact::ID: {
+      auto message_contact = move_tl_object_as<telegram_api::messageMediaContact>(media);
+      if (message_contact->user_id_ != 0) {
+        td_->contacts_manager_->get_user_id_object(UserId(message_contact->user_id_),
+                                                   "messageMediaContact");  // to ensure updateUser
+      }
+      return make_unique<MessageContact>(Contact(message_contact->phone_number_, message_contact->first_name_,
+                                                 message_contact->last_name_, message_contact->user_id_));
+    }
+    case telegram_api::messageMediaDocument::ID: {
+      auto message_document = move_tl_object_as<telegram_api::messageMediaDocument>(media);
+      if ((message_document->flags_ & telegram_api::messageMediaDocument::DOCUMENT_MASK) == 0) {
+        if ((message_document->flags_ & telegram_api::messageMediaDocument::TTL_SECONDS_MASK) == 0) {
+          LOG(ERROR) << "Receive messageMediaDocument without document and TTL: "
+                     << oneline(to_string(message_document));
+          break;
+        }
+
+        return make_unique<MessageExpiredVideo>();
+      }
+
+      auto document_ptr = std::move(message_document->document_);
+      int32 document_id = document_ptr->get_id();
+      if (document_id == telegram_api::documentEmpty::ID) {
+        break;
+      }
+      CHECK(document_id == telegram_api::document::ID);
+
+      if (ttl != nullptr && (message_document->flags_ & telegram_api::messageMediaDocument::TTL_SECONDS_MASK) != 0) {
+        *ttl = message_document->ttl_seconds_;
+      }
+      return get_message_document(move_tl_object_as<telegram_api::document>(document_ptr), owner_dialog_id,
+                                  std::move(message), is_content_read, nullptr);
+    }
+    case telegram_api::messageMediaGame::ID: {
+      auto message_game = move_tl_object_as<telegram_api::messageMediaGame>(media);
+
+      auto m = make_unique<MessageGame>(Game(td_, std::move(message_game->game_), owner_dialog_id));
+      if (m->game.empty()) {
+        break;
+      }
+
+      m->game.set_bot_user_id(via_bot_user_id);
+      m->game.set_message_text(std::move(message));
+
+      return std::move(m);
+    }
+    case telegram_api::messageMediaInvoice::ID: {
+      auto message_invoice = move_tl_object_as<telegram_api::messageMediaInvoice>(media);
+
+      MessageId receipt_message_id;
+      if ((message_invoice->flags_ & telegram_api::messageMediaInvoice::RECEIPT_MSG_ID_MASK) != 0) {
+        receipt_message_id = MessageId(ServerMessageId(message_invoice->receipt_msg_id_));
+        if (!receipt_message_id.is_valid()) {
+          LOG(ERROR) << "Receive as receipt message " << receipt_message_id << " in " << owner_dialog_id;
+          receipt_message_id = MessageId();
+        }
+      }
+      bool need_shipping_address =
+          (message_invoice->flags_ & telegram_api::messageMediaInvoice::SHIPPING_ADDRESS_REQUESTED_MASK) != 0;
+      bool is_test = (message_invoice->flags_ & telegram_api::messageMediaInvoice::TEST_MASK) != 0;
+      return make_unique<MessageInvoice>(std::move(message_invoice->title_), std::move(message_invoice->description_),
+                                         get_web_document_photo(std::move(message_invoice->photo_), owner_dialog_id),
+                                         std::move(message_invoice->start_param_), message_invoice->total_amount_,
+                                         std::move(message_invoice->currency_), is_test, need_shipping_address,
+                                         receipt_message_id);
+    }
+    case telegram_api::messageMediaWebPage::ID: {
+      auto media_web_page = move_tl_object_as<telegram_api::messageMediaWebPage>(media);
+      auto web_page_id = td_->web_pages_manager_->on_get_web_page(std::move(media_web_page->webpage_), owner_dialog_id);
+      return make_unique<MessageText>(std::move(message), web_page_id);
+    }
+
+    case telegram_api::messageMediaUnsupported::ID: {
+      return make_unique<MessageUnsupported>();
+    }
+    default:
+      UNREACHABLE();
+  }
+
+  // explicit empty media message
+  return make_unique<MessageText>(std::move(message), WebPageId());
+}
+
+unique_ptr<MessageContent> MessagesManager::dup_message_content(DialogId dialog_id, const MessageContent *content,
+                                                                bool for_forward) {
+  CHECK(content != nullptr);
+
+  bool to_secret = dialog_id.get_type() == DialogType::SecretChat;
+  auto fix_file_id = [dialog_id, to_secret, file_manager = td_->file_manager_.get()](FileId file_id) {
+    auto file_view = file_manager->get_file_view(file_id);
+    if (to_secret && !file_view.is_encrypted()) {
+      auto download_file_id = file_manager->dup_file_id(file_id);
+      file_id = file_manager
+                    ->register_generate(FileType::Encrypted, FileLocationSource::FromServer, "",
+                                        PSTRING() << "#file_id#" << download_file_id.get(), dialog_id, file_view.size())
+                    .ok();
+    }
+    return file_manager->dup_file_id(file_id);
+  };
+
+  FileId thumbnail_file_id;
+  if (to_secret) {
+    thumbnail_file_id = get_message_content_thumbnail_file_id(content);
+  }
+  switch (content->get_id()) {
+    case MessageAnimation::ID: {
+      auto result = make_unique<MessageAnimation>(*static_cast<const MessageAnimation *>(content));
+      if (td_->documents_manager_->has_input_media(result->file_id, thumbnail_file_id, to_secret)) {
+        return std::move(result);
+      }
+      result->file_id = td_->animations_manager_->dup_animation(fix_file_id(result->file_id), result->file_id);
+      CHECK(result->file_id.is_valid());
+      return std::move(result);
+    }
+    case MessageAudio::ID: {
+      auto result = make_unique<MessageAudio>(*static_cast<const MessageAudio *>(content));
+      if (td_->documents_manager_->has_input_media(result->file_id, thumbnail_file_id, to_secret)) {
+        return std::move(result);
+      }
+      result->file_id = td_->audios_manager_->dup_audio(fix_file_id(result->file_id), result->file_id);
+      CHECK(result->file_id.is_valid());
+      return std::move(result);
+    }
+    case MessageContact::ID:
+      return make_unique<MessageContact>(*static_cast<const MessageContact *>(content));
+    case MessageDocument::ID: {
+      auto result = make_unique<MessageDocument>(*static_cast<const MessageDocument *>(content));
+      if (td_->documents_manager_->has_input_media(result->file_id, thumbnail_file_id, to_secret)) {
+        return std::move(result);
+      }
+      result->file_id = td_->documents_manager_->dup_document(fix_file_id(result->file_id), result->file_id);
+      CHECK(result->file_id.is_valid());
+      return std::move(result);
+    }
+    case MessageGame::ID:
+      return make_unique<MessageGame>(*static_cast<const MessageGame *>(content));
+    case MessageInvoice::ID:
+      return make_unique<MessageInvoice>(*static_cast<const MessageInvoice *>(content));
+    case MessageLiveLocation::ID:
+      if (to_secret || for_forward) {
+        return make_unique<MessageLocation>(Location(static_cast<const MessageLiveLocation *>(content)->location));
+      } else {
+        return make_unique<MessageLiveLocation>(*static_cast<const MessageLiveLocation *>(content));
+      }
+    case MessageLocation::ID:
+      return make_unique<MessageLocation>(*static_cast<const MessageLocation *>(content));
+    case MessagePhoto::ID: {
+      auto result = make_unique<MessagePhoto>(*static_cast<const MessagePhoto *>(content));
+
+      if (result->photo.photos.size() > 2 && !to_secret) {
+        // already sent photo
+        return std::move(result);
+      }
+
+      // Find 'i' or largest
+      CHECK(!result->photo.photos.empty());
+      PhotoSize photo;
+      for (const auto &size : result->photo.photos) {
+        if (size.type == 'i') {
+          photo = size;
+        }
+      }
+      if (photo.type == 0) {
+        for (const auto &size : result->photo.photos) {
+          if (photo.type == 0 || photo.size < size.size) {
+            photo = size;
+          }
+        }
+      }
+
+      // Find 't' or smallest
+      PhotoSize thumbnail;
+      for (const auto &size : result->photo.photos) {
+        if (size.type == 't') {
+          thumbnail = size;
+        }
+      }
+      if (thumbnail.type == 0) {
+        for (const auto &size : result->photo.photos) {
+          if (size.type != photo.type && (thumbnail.type == 0 || thumbnail.size > size.size)) {
+            thumbnail = size;
+          }
+        }
+      }
+
+      result->photo.photos.clear();
+      if (thumbnail.type != 0) {
+        thumbnail.type = 't';
+        result->photo.photos.push_back(std::move(thumbnail));
+      }
+      photo.type = 'i';
+      result->photo.photos.push_back(std::move(photo));
+
+      if (photo_has_input_media(td_->file_manager_.get(), result->photo, to_secret)) {
+        return std::move(result);
+      }
+
+      result->photo.photos.back().file_id = fix_file_id(result->photo.photos.back().file_id);
+      if (thumbnail.type != 0) {
+        result->photo.photos[0].file_id = td_->file_manager_->dup_file_id(result->photo.photos[0].file_id);
+      }
+      return std::move(result);
+    }
+    case MessageSticker::ID: {
+      auto result = make_unique<MessageSticker>(*static_cast<const MessageSticker *>(content));
+      if (td_->stickers_manager_->has_input_media(result->file_id, to_secret)) {
+        return std::move(result);
+      }
+      result->file_id = td_->stickers_manager_->dup_sticker(fix_file_id(result->file_id), result->file_id);
+      CHECK(result->file_id.is_valid());
+      return std::move(result);
+    }
+    case MessageText::ID:
+      return make_unique<MessageText>(*static_cast<const MessageText *>(content));
+    case MessageVenue::ID:
+      return make_unique<MessageVenue>(*static_cast<const MessageVenue *>(content));
+    case MessageVideo::ID: {
+      auto result = make_unique<MessageVideo>(*static_cast<const MessageVideo *>(content));
+      if (td_->documents_manager_->has_input_media(result->file_id, thumbnail_file_id, to_secret)) {
+        return std::move(result);
+      }
+      result->file_id = td_->videos_manager_->dup_video(fix_file_id(result->file_id), result->file_id);
+      CHECK(result->file_id.is_valid());
+      return std::move(result);
+    }
+    case MessageVideoNote::ID: {
+      auto result = make_unique<MessageVideoNote>(*static_cast<const MessageVideoNote *>(content));
+      result->is_viewed = false;
+      if (td_->documents_manager_->has_input_media(result->file_id, thumbnail_file_id, to_secret)) {
+        return std::move(result);
+      }
+      result->file_id = td_->video_notes_manager_->dup_video_note(fix_file_id(result->file_id), result->file_id);
+      CHECK(result->file_id.is_valid());
+      return std::move(result);
+    }
+    case MessageVoiceNote::ID: {
+      auto result = make_unique<MessageVoiceNote>(*static_cast<const MessageVoiceNote *>(content));
+      result->is_listened = false;
+      if (td_->documents_manager_->has_input_media(result->file_id, thumbnail_file_id, to_secret)) {
+        return std::move(result);
+      }
+      result->file_id = td_->voice_notes_manager_->dup_voice_note(fix_file_id(result->file_id), result->file_id);
+      CHECK(result->file_id.is_valid());
+      return std::move(result);
+    }
+    case MessageUnsupported::ID:
+    case MessageChatCreate::ID:
+    case MessageChatChangeTitle::ID:
+    case MessageChatChangePhoto::ID:
+    case MessageChatDeletePhoto::ID:
+    case MessageChatDeleteHistory::ID:
+    case MessageChatAddUsers::ID:
+    case MessageChatJoinedByLink::ID:
+    case MessageChatDeleteUser::ID:
+    case MessageChatMigrateTo::ID:
+    case MessageChannelCreate::ID:
+    case MessageChannelMigrateFrom::ID:
+    case MessagePinMessage::ID:
+    case MessageGameScore::ID:
+    case MessageScreenshotTaken::ID:
+    case MessageChatSetTtl::ID:
+    case MessageCall::ID:
+    case MessagePaymentSuccessful::ID:
+    case MessageContactRegistered::ID:
+    case MessageExpiredPhoto::ID:
+    case MessageExpiredVideo::ID:
+    case MessageCustomServiceAction::ID:
+    case MessageWebsiteConnected::ID:
+      return nullptr;
+    default:
+      UNREACHABLE();
+  }
+  UNREACHABLE();
+  return nullptr;
+}
+
+unique_ptr<MessageContent> MessagesManager::get_message_action_content(
+    tl_object_ptr<telegram_api::MessageAction> &&action, DialogId owner_dialog_id,
+    MessageId reply_to_message_id) const {
+  CHECK(action != nullptr);
+
+  switch (action->get_id()) {
+    case telegram_api::messageActionEmpty::ID:
+      LOG(ERROR) << "Receive empty message action";
+      break;
+    case telegram_api::messageActionChatCreate::ID: {
+      auto chat_create = move_tl_object_as<telegram_api::messageActionChatCreate>(action);
+
+      vector<UserId> participant_user_ids;
+      participant_user_ids.reserve(chat_create->users_.size());
+      for (auto &user : chat_create->users_) {
+        UserId user_id(user);
+        if (user_id.is_valid()) {
+          participant_user_ids.push_back(user_id);
+        } else {
+          LOG(ERROR) << "Receive invalid " << user_id;
+        }
+      }
+
+      return make_unique<MessageChatCreate>(std::move(chat_create->title_), std::move(participant_user_ids));
+    }
+    case telegram_api::messageActionChatEditTitle::ID: {
+      auto chat_edit_title = move_tl_object_as<telegram_api::messageActionChatEditTitle>(action);
+      return make_unique<MessageChatChangeTitle>(std::move(chat_edit_title->title_));
+    }
+    case telegram_api::messageActionChatEditPhoto::ID: {
+      auto chat_edit_photo = move_tl_object_as<telegram_api::messageActionChatEditPhoto>(action);
+
+      auto photo_ptr = std::move(chat_edit_photo->photo_);
+      int32 photo_id = photo_ptr->get_id();
+      if (photo_id == telegram_api::photoEmpty::ID) {
+        break;
+      }
+      CHECK(photo_id == telegram_api::photo::ID);
+
+      return make_unique<MessageChatChangePhoto>(
+          get_photo(td_->file_manager_.get(), move_tl_object_as<telegram_api::photo>(photo_ptr), owner_dialog_id));
+    }
+    case telegram_api::messageActionChatDeletePhoto::ID: {
+      return make_unique<MessageChatDeletePhoto>();
+    }
+    case telegram_api::messageActionHistoryClear::ID: {
+      return make_unique<MessageChatDeleteHistory>();
+    }
+    case telegram_api::messageActionChatAddUser::ID: {
+      auto chat_add_user = move_tl_object_as<telegram_api::messageActionChatAddUser>(action);
+
+      vector<UserId> user_ids;
+      user_ids.reserve(chat_add_user->users_.size());
+      for (auto &user : chat_add_user->users_) {
+        UserId user_id(user);
+        if (user_id.is_valid()) {
+          user_ids.push_back(user_id);
+        } else {
+          LOG(ERROR) << "Receive invalid " << user_id;
+        }
+      }
+
+      return make_unique<MessageChatAddUsers>(std::move(user_ids));
+    }
+    case telegram_api::messageActionChatJoinedByLink::ID:
+      return make_unique<MessageChatJoinedByLink>();
+    case telegram_api::messageActionChatDeleteUser::ID: {
+      auto chat_delete_user = move_tl_object_as<telegram_api::messageActionChatDeleteUser>(action);
+
+      UserId user_id(chat_delete_user->user_id_);
+      if (!user_id.is_valid()) {
+        LOG(ERROR) << "Receive invalid " << user_id;
+        break;
+      }
+
+      return make_unique<MessageChatDeleteUser>(user_id);
+    }
+    case telegram_api::messageActionChatMigrateTo::ID: {
+      auto chat_migrate_to = move_tl_object_as<telegram_api::messageActionChatMigrateTo>(action);
+
+      ChannelId migrated_to_channel_id(chat_migrate_to->channel_id_);
+      if (!migrated_to_channel_id.is_valid()) {
+        LOG(ERROR) << "Receive invalid " << migrated_to_channel_id;
+        break;
+      }
+
+      return make_unique<MessageChatMigrateTo>(migrated_to_channel_id);
+    }
+    case telegram_api::messageActionChannelCreate::ID: {
+      auto channel_create = move_tl_object_as<telegram_api::messageActionChannelCreate>(action);
+      return make_unique<MessageChannelCreate>(std::move(channel_create->title_));
+    }
+    case telegram_api::messageActionChannelMigrateFrom::ID: {
+      auto channel_migrate_from = move_tl_object_as<telegram_api::messageActionChannelMigrateFrom>(action);
+
+      ChatId chat_id(channel_migrate_from->chat_id_);
+      LOG_IF(ERROR, !chat_id.is_valid()) << "Receive invalid " << chat_id;
+
+      return make_unique<MessageChannelMigrateFrom>(std::move(channel_migrate_from->title_), chat_id);
+    }
+    case telegram_api::messageActionPinMessage::ID: {
+      if (!reply_to_message_id.is_valid()) {
+        LOG(ERROR) << "Receive pinned message with " << reply_to_message_id;
+        reply_to_message_id = MessageId();
+      }
+      return make_unique<MessagePinMessage>(reply_to_message_id);
+    }
+    case telegram_api::messageActionGameScore::ID: {
+      if (!reply_to_message_id.is_valid()) {
+        LOG_IF(ERROR, !td_->auth_manager_->is_bot()) << "Receive game score with " << reply_to_message_id;
+        reply_to_message_id = MessageId();
+      }
+      auto game_score = move_tl_object_as<telegram_api::messageActionGameScore>(action);
+      return make_unique<MessageGameScore>(reply_to_message_id, game_score->game_id_, game_score->score_);
+    }
+    case telegram_api::messageActionPhoneCall::ID: {
+      auto phone_call = move_tl_object_as<telegram_api::messageActionPhoneCall>(action);
+      auto duration =
+          (phone_call->flags_ & telegram_api::messageActionPhoneCall::DURATION_MASK) != 0 ? phone_call->duration_ : 0;
+      return make_unique<MessageCall>(phone_call->call_id_, duration, get_call_discard_reason(phone_call->reason_));
+    }
+    case telegram_api::messageActionPaymentSent::ID: {
+      LOG_IF(ERROR, td_->auth_manager_->is_bot()) << "Receive MessageActionPaymentSent";
+      if (!reply_to_message_id.is_valid()) {
+        LOG(ERROR) << "Receive succesful payment message with " << reply_to_message_id;
+        reply_to_message_id = MessageId();
+      }
+      auto payment_sent = move_tl_object_as<telegram_api::messageActionPaymentSent>(action);
+      return make_unique<MessagePaymentSuccessful>(reply_to_message_id, std::move(payment_sent->currency_),
+                                                   payment_sent->total_amount_);
+    }
+    case telegram_api::messageActionPaymentSentMe::ID: {
+      LOG_IF(ERROR, !td_->auth_manager_->is_bot()) << "Receive MessageActionPaymentSentMe";
+      if (!reply_to_message_id.is_valid()) {
+        LOG(ERROR) << "Receive succesful payment message with " << reply_to_message_id;
+        reply_to_message_id = MessageId();
+      }
+      auto payment_sent = move_tl_object_as<telegram_api::messageActionPaymentSentMe>(action);
+      auto result = make_unique<MessagePaymentSuccessful>(reply_to_message_id, std::move(payment_sent->currency_),
+                                                          payment_sent->total_amount_);
+      result->invoice_payload = payment_sent->payload_.as_slice().str();
+      result->shipping_option_id = std::move(payment_sent->shipping_option_id_);
+      result->order_info = get_order_info(std::move(payment_sent->info_));
+      result->telegram_payment_charge_id = std::move(payment_sent->charge_->id_);
+      result->provider_payment_charge_id = std::move(payment_sent->charge_->provider_charge_id_);
+      return std::move(result);
+    }
+    case telegram_api::messageActionScreenshotTaken::ID: {
+      return make_unique<MessageScreenshotTaken>();
+    }
+    case telegram_api::messageActionCustomAction::ID: {
+      auto custom_action = move_tl_object_as<telegram_api::messageActionCustomAction>(action);
+      return make_unique<MessageCustomServiceAction>(std::move(custom_action->message_));
+    }
+    case telegram_api::messageActionBotAllowed::ID: {
+      auto bot_allowed = move_tl_object_as<telegram_api::messageActionBotAllowed>(action);
+      return make_unique<MessageWebsiteConnected>(std::move(bot_allowed->domain_));
+    }
+    default:
+      UNREACHABLE();
+  }
+  // explicit empty or wrong action
+  return make_unique<MessageText>(FormattedText(), WebPageId());
+}
+
+int32 MessagesManager::get_random_y(MessageId message_id) {
+  return static_cast<int32>(static_cast<uint32>(message_id.get() * 2101234567u));
+}
+
+MessagesManager::Message *MessagesManager::add_message_to_dialog(DialogId dialog_id, unique_ptr<Message> message,
+                                                                 bool from_update, bool *need_update,
+                                                                 bool *need_update_dialog_pos, const char *source) {
+  CHECK(message != nullptr);
+  CHECK(dialog_id.get_type() != DialogType::None);
+  CHECK(need_update_dialog_pos != nullptr);
+
+  MessageId message_id = message->message_id;
+  if (!message_id.is_valid()) {
+    LOG(ERROR) << "Receive " << message_id << " in " << dialog_id << " from " << source;
+    debug_add_message_to_dialog_fail_reason = "invalid message id";
+    return nullptr;
+  }
+
+  // TODO remove creation of dialog from this function, use cgc or cpc or something else
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    d = add_dialog(dialog_id);
+    *need_update_dialog_pos = true;
+  } else {
+    CHECK(d->dialog_id == dialog_id);
+  }
+  return add_message_to_dialog(d, std::move(message), from_update, need_update, need_update_dialog_pos, source);
+}
+
+MessagesManager::Message *MessagesManager::add_message_to_dialog(Dialog *d, unique_ptr<Message> message,
+                                                                 bool from_update, bool *need_update,
+                                                                 bool *need_update_dialog_pos, const char *source) {
+  CHECK(message != nullptr);
+  CHECK(d != nullptr);
+  CHECK(need_update != nullptr);
+  CHECK(need_update_dialog_pos != nullptr);
+  CHECK(source != nullptr);
+
+  DialogId dialog_id = d->dialog_id;
+  MessageId message_id = message->message_id;
+
+  if (d->deleted_message_ids.count(message_id)) {
+    LOG(INFO) << "Skip adding deleted " << message_id << " to " << dialog_id << " from " << source;
+    debug_add_message_to_dialog_fail_reason = "adding deleted message";
+    return nullptr;
+  }
+  if (message_id.get() <= d->last_clear_history_message_id.get()) {
+    LOG(INFO) << "Skip adding cleared " << message_id << " to " << dialog_id << " from " << source;
+    debug_add_message_to_dialog_fail_reason = "cleared full history";
+    return nullptr;
+  }
+  if (d->deleted_message_ids.count(message->reply_to_message_id)) {
+    // LOG(INFO) << "Remove reply to deleted " << message->reply_to_message_id << " in " << message_id << " from " << dialog_id << " from " << source;
+    // we don't want to lose information that the message was a reply for now
+    // message->reply_to_message_id = MessageId();
+  }
+
+  LOG(INFO) << "Adding " << message_id << " of type " << message->content->get_id() << " to " << dialog_id << " from "
+            << source << ". Last new is " << d->last_new_message_id << ", last is " << d->last_message_id
+            << ", from_update = " << from_update << ", have_previous = " << message->have_previous
+            << ", have_next = " << message->have_next;
+
+  if (!message_id.is_valid()) {
+    LOG(ERROR) << "Receive " << message_id << " in " << dialog_id << " from " << source;
+    CHECK(!message->from_database);
+    debug_add_message_to_dialog_fail_reason = "invalid message id";
+    return nullptr;
+  }
+
+  auto message_content_id = message->content->get_id();
+  if (is_debug_message_op_enabled()) {
+    d->debug_message_op.emplace_back(Dialog::MessageOp::Add, message_id, message_content_id, from_update,
+                                     message->have_previous, message->have_next, source);
+  }
+
+  message->last_access_date = G()->unix_time_cached();
+
+  if (*need_update) {
+    CHECK(from_update);
+  }
+  if (from_update) {
+    CHECK(message->have_next);
+    CHECK(message->have_previous);
+    CHECK(!message_id.is_yet_unsent());
+    if (message_id.get() <= d->last_new_message_id.get() && d->dialog_id.get_type() != DialogType::Channel) {
+      if (!G()->parameters().use_message_db) {
+        LOG(ERROR) << "New " << message_id << " in " << dialog_id << " from " << source
+                   << " has id less than last_new_message_id = " << d->last_new_message_id;
+        dump_debug_message_op(d);
+      }
+    }
+  }
+
+  if (!from_update && message_id.is_server() && d->last_new_message_id != MessageId() &&
+      message_id.get() > d->last_new_message_id.get()) {
+    if (!message->from_database) {
+      LOG(ERROR) << "Ignore " << message_id << " in " << dialog_id << " received not through update from " << source
+                 << ". Last new is " << d->last_new_message_id << ", "
+                 << to_string(get_message_object(dialog_id, message.get()));
+      dump_debug_message_op(d, 3);
+      if (dialog_id.get_type() == DialogType::Channel && have_input_peer(dialog_id, AccessRights::Read)) {
+        channel_get_difference_retry_timeout_.add_timeout_in(dialog_id.get(), 0.001);
+      }
+    } else {
+      LOG(INFO) << "Ignore " << message_id << " in " << dialog_id << " received not through update from " << source;
+    }
+    debug_add_message_to_dialog_fail_reason = "too new message not from update";
+    return nullptr;
+  }
+  if ((message_id.is_server() || (message_id.is_local() && dialog_id.get_type() == DialogType::SecretChat)) &&
+      message_id.get() <= d->max_unavailable_message_id.get()) {
+    LOG(INFO) << "Can't add an unavailable " << message_id << " to " << dialog_id << " from " << source;
+    if (message->from_database) {
+      delete_message_from_database(d, message_id, message.get(), true);
+    }
+    debug_add_message_to_dialog_fail_reason = "ignore unavailable message";
+    return nullptr;
+  }
+
+  if (message_content_id == MessageText::ID) {
+    auto web_page_id = static_cast<const MessageText *>(message->content.get())->web_page_id;
+    if (web_page_id.is_valid() && !td_->web_pages_manager_->have_web_page(web_page_id)) {
+      waiting_for_web_page_messages_.emplace(dialog_id, message_id);
+      send_closure(G()->web_pages_manager(), &WebPagesManager::wait_for_pending_web_page, dialog_id, message_id,
+                   web_page_id);
+    }
+  }
+
+  if (*need_update && message_id.get() <= d->last_new_message_id.get()) {
+    *need_update = false;
+  }
+
+  bool auto_attach = message->have_previous && message->have_next &&
+                     (from_update || message_id.is_local() || message_id.is_yet_unsent());
+  if (message_content_id == MessageChatDeleteHistory::ID) {
+    auto m = delete_message(d, message_id, true, need_update_dialog_pos, "message chat delete history");
+    if (m != nullptr) {
+      send_update_delete_messages(dialog_id, {m->message_id.get()}, true, false);
+    }
+    int32 last_message_date = 0;
+    if (d->last_message_id != MessageId()) {
+      auto last_message = get_message(d, d->last_message_id);
+      CHECK(last_message != nullptr);
+      last_message_date = last_message->date - 1;
+    } else {
+      last_message_date = d->last_clear_history_date;
+    }
+    if (message->date > last_message_date) {
+      set_dialog_last_clear_history_date(d, message->date, message_id, "update_last_clear_history_date");
+      on_dialog_updated(dialog_id, "update_last_clear_history_date");
+      *need_update_dialog_pos = true;
+    }
+    LOG(INFO) << "Process MessageChatDeleteHistory in " << message_id << " in " << dialog_id << " with date "
+              << message->date << " from " << source;
+    CHECK(!message->from_database);
+    debug_add_message_to_dialog_fail_reason = "skip adding MessageChatDeleteHistory";
+    return nullptr;
+  }
+
+  if (!message->from_database) {
+    // load message from database before updating it
+    get_message_force(d, message_id);
+  }
+
+  if (message->reply_markup != nullptr &&
+      (message->reply_markup->type == ReplyMarkup::Type::RemoveKeyboard ||
+       (message->reply_markup->type == ReplyMarkup::Type::ForceReply && !message->reply_markup->is_personal)) &&
+      !td_->auth_manager_->is_bot()) {
+    if (*need_update && message->reply_markup->is_personal) {  // if this keyboard is for us
+      if (d->reply_markup_message_id != MessageId()) {
+        const Message *old_message = get_message_force(d, d->reply_markup_message_id);
+        if (old_message == nullptr || old_message->sender_user_id == message->sender_user_id) {
+          set_dialog_reply_markup(d, MessageId());
+        }
+      }
+    }
+    message->had_reply_markup = message->reply_markup->is_personal;
+    message->reply_markup = nullptr;
+  }
+
+  if (from_update) {
+    cancel_user_dialog_action(dialog_id, message.get());
+  }
+
+  unique_ptr<Message> *v = &d->messages;
+  while (*v != nullptr && (*v)->random_y >= message->random_y) {
+    if ((*v)->message_id.get() < message_id.get()) {
+      v = &(*v)->right;
+    } else if ((*v)->message_id == message_id) {
+      LOG(INFO) << "Adding already existing " << message_id << " in " << dialog_id << " from " << source;
+      if (*need_update) {
+        *need_update = false;
+        if (!G()->parameters().use_message_db) {
+          LOG(ERROR) << "Receive again " << (message->is_outgoing ? "outgoing" : "incoming")
+                     << (message->forward_info == nullptr ? " not" : "") << " forwarded " << message_id
+                     << " with content of type " << message_content_id << " in " << dialog_id << " from " << source
+                     << ", current last new is " << d->last_new_message_id << ", last is " << d->last_message_id << ". "
+                     << td_->updates_manager_->get_state();
+          dump_debug_message_op(d, 1);
+        }
+      }
+      if (auto_attach) {
+        CHECK(message->have_previous);
+        CHECK(message->have_next);
+        message->have_previous = false;
+        message->have_next = false;
+      }
+      if (!message->from_database) {
+        bool was_deleted = delete_active_live_location(dialog_id, v->get());
+        update_message(d, *v, std::move(message), true, need_update_dialog_pos);
+        if (was_deleted) {
+          try_add_active_live_location(dialog_id, v->get());
+        }
+      }
+      return v->get();
+    } else {
+      v = &(*v)->left;
+    }
+  }
+
+  if (d->have_full_history && !message->from_database && !from_update && !message_id.is_local() &&
+      !message_id.is_yet_unsent()) {
+    LOG(ERROR) << "Have full history in " << dialog_id << ", but receive unknown " << message_id << " from " << source
+               << ". Last new is " << d->last_new_message_id << ", last is " << d->last_message_id
+               << ", first database is " << d->first_database_message_id << ", last database is "
+               << d->last_database_message_id << ", last read inbox is " << d->last_read_inbox_message_id
+               << ", last read outbox is " << d->last_read_inbox_message_id << ", last read all mentions is "
+               << d->last_read_all_mentions_message_id << ", max unavailable is " << d->max_unavailable_message_id
+               << ", last assigned is " << d->last_assigned_message_id;
+    d->have_full_history = false;
+    on_dialog_updated(dialog_id, "drop have_full_history");
+  }
+
+  if (!d->is_opened && d->messages != nullptr && is_message_unload_enabled()) {
+    LOG(INFO) << "Schedule unload of " << dialog_id;
+    pending_unload_dialog_timeout_.add_timeout_in(dialog_id.get(), DIALOG_UNLOAD_DELAY);
+  }
+
+  if (message->ttl > 0 && message->ttl_expires_at != 0) {
+    auto now = Time::now();
+    if (message->ttl_expires_at <= now) {
+      if (d->dialog_id.get_type() == DialogType::SecretChat) {
+        LOG(INFO) << "Can't add " << message_id << " with expired TTL to " << dialog_id << " from " << source;
+        delete_message_from_database(d, message_id, message.get(), true);
+        debug_add_message_to_dialog_fail_reason = "delete expired by TTL message";
+        return nullptr;
+      } else {
+        on_message_ttl_expired_impl(d, message.get());
+        message_content_id = message->content->get_id();
+        if (message->from_database) {
+          add_message_to_database(d, message.get(), "add expired message to dialog");
+        }
+      }
+    } else {
+      ttl_register_message(dialog_id, message.get(), now);
+    }
+  }
+
+  LOG(INFO) << "Adding not found " << message_id << " to " << dialog_id << " from " << source;
+  if (d->is_empty) {
+    d->is_empty = false;
+    *need_update_dialog_pos = true;
+  }
+
+  if (dialog_id.get_type() == DialogType::Channel && !message->contains_unread_mention &&
+      message->date <
+          G()->unix_time_cached() - G()->shared_config().get_option_integer("channels_read_media_period",
+                                                                            (G()->is_test_dc() ? 300 : 7 * 86400))) {
+    update_opened_message_content(message.get());
+  }
+
+  if (message->contains_unread_mention && message_id.get() <= d->last_read_all_mentions_message_id.get()) {
+    message->contains_unread_mention = false;
+  }
+
+  if (message_id.is_yet_unsent() && message->reply_to_message_id.is_valid() &&
+      !message->reply_to_message_id.is_yet_unsent()) {
+    replied_by_yet_unsent_messages_[FullMessageId{dialog_id, message->reply_to_message_id}]++;
+  }
+
+  if (G()->parameters().use_file_db && message_id.is_yet_unsent() && !message->via_bot_user_id.is_valid()) {
+    auto queue_id = get_sequence_dispatcher_id(dialog_id, message_content_id);
+    if (queue_id & 1) {
+      LOG(INFO) << "Add " << message_id << " from " << source << " to queue " << queue_id;
+      yet_unsent_media_queues_[queue_id][message_id.get()];  // reserve place for promise
+      if (!td_->auth_manager_->is_bot() && !is_broadcast_channel(dialog_id)) {
+        pending_send_dialog_action_timeout_.add_timeout_in(dialog_id.get(), 1.0);
+      }
+    }
+  }
+
+  if (from_update && message_id.get() > d->last_new_message_id.get()) {
+    CHECK(!message_id.is_yet_unsent());
+    if (d->dialog_id.get_type() == DialogType::SecretChat || message_id.is_server()) {
+      // can delete messages, therefore must be called before message attaching/adding
+      set_dialog_last_new_message_id(d, message_id, "add_message_to_dialog");
+    }
+  }
+  if (!(d->have_full_history && auto_attach) && d->last_message_id.is_valid() &&
+      d->last_message_id.get() < MessageId(ServerMessageId(1)).get() &&
+      message_id.get() >= MessageId(ServerMessageId(1)).get()) {
+    set_dialog_last_message_id(d, MessageId(), "add_message_to_dialog");
+
+    set_dialog_first_database_message_id(d, MessageId(), "add_message_to_dialog");
+    set_dialog_last_database_message_id(d, MessageId(), "add_message_to_dialog");
+    d->have_full_history = false;
+    for (auto &first_message_id : d->first_database_message_id_by_index) {
+      first_message_id = MessageId();
+    }
+    std::fill(d->message_count_by_index.begin(), d->message_count_by_index.end(), -1);
+    d->local_unread_count = 0;  // read all local messages. They will not be reachable anymore
+
+    on_dialog_updated(dialog_id, "add gap to dialog");
+
+    send_update_chat_last_message(d, "add gap to dialog");
+    *need_update_dialog_pos = false;
+  }
+
+  bool is_attached = false;
+  if (auto_attach) {
+    LOG(INFO) << "Trying to auto attach " << message_id;
+    auto it = MessagesIterator(d, message_id);
+    Message *previous_message = *it;
+    if (previous_message != nullptr) {
+      auto previous_message_id = previous_message->message_id;
+      CHECK(previous_message_id.get() < message_id.get());
+      if (previous_message->have_next ||
+          (d->last_message_id.is_valid() && previous_message_id.get() >= d->last_message_id.get())) {
+        if (message_id.is_server() && previous_message_id.is_server() && previous_message->have_next) {
+          ++it;
+          auto next_message = *it;
+          if (next_message != nullptr) {
+            if (next_message->message_id.is_server()) {
+              LOG(ERROR) << "Attach " << message_id << " from " << source << " before " << next_message->message_id
+                         << " and after " << previous_message_id << " in " << dialog_id;
+              dump_debug_message_op(d);
+            }
+          } else {
+            LOG(ERROR) << "Have_next is true, but there is no next message after " << previous_message_id << " from "
+                       << source << " in " << dialog_id;
+            dump_debug_message_op(d);
+          }
+        }
+
+        LOG(INFO) << "Attach " << message_id << " to the previous " << previous_message_id;
+        message->have_previous = true;
+        message->have_next = previous_message->have_next;
+        previous_message->have_next = true;
+        is_attached = true;
+      }
+    }
+    if (!is_attached && !message_id.is_yet_unsent()) {
+      // message may be attached to the next message if there is no previous message
+      Message *cur = d->messages.get();
+      Message *next_message = nullptr;
+      while (cur != nullptr) {
+        if (cur->message_id.get() < message_id.get()) {
+          cur = cur->right.get();
+        } else {
+          next_message = cur;
+          cur = cur->left.get();
+        }
+      }
+      if (next_message != nullptr) {
+        CHECK(!next_message->have_previous);
+        LOG(INFO) << "Attach " << message_id << " to the next " << next_message->message_id;
+        LOG_IF(ERROR, from_update) << "Attach " << message_id << " from " << source << " to the next "
+                                   << next_message->message_id << " in " << dialog_id;
+        message->have_next = true;
+        message->have_previous = next_message->have_previous;
+        next_message->have_previous = true;
+        is_attached = true;
+      }
+    }
+    if (!is_attached) {
+      LOG(INFO) << "Can't attach " << message_id;
+      message->have_previous = false;
+      message->have_next = false;
+    }
+  }
+
+  UserId my_user_id(td_->contacts_manager_->get_my_id("add_message_to_dialog"));
+  DialogId my_dialog_id(my_user_id);
+  if (*need_update && message_id.get() > d->last_read_inbox_message_id.get() && !td_->auth_manager_->is_bot()) {
+    if (!message->is_outgoing && dialog_id != my_dialog_id) {
+      int32 server_unread_count = d->server_unread_count;
+      int32 local_unread_count = d->local_unread_count;
+      if (message_id.is_server()) {
+        server_unread_count++;
+      } else {
+        local_unread_count++;
+      }
+      set_dialog_last_read_inbox_message_id(d, MessageId::min(), server_unread_count, local_unread_count, false,
+                                            source);
+    } else {
+      // if outgoing message has id one greater than last_read_inbox_message_id than definitely there is no
+      // unread incoming message before it
+      if (message_id.is_server() && d->last_read_inbox_message_id.is_valid() &&
+          d->last_read_inbox_message_id.is_server() &&
+          message_id.get_server_message_id().get() == d->last_read_inbox_message_id.get_server_message_id().get() + 1) {
+        read_history_inbox(d->dialog_id, message_id, 0, "add_message_to_dialog");
+      }
+    }
+  }
+  if (*need_update && message->contains_unread_mention) {
+    d->unread_mention_count++;
+    d->message_count_by_index[search_messages_filter_index(SearchMessagesFilter::UnreadMention)] =
+        d->unread_mention_count;
+    send_update_chat_unread_mention_count(d);
+  }
+  if (*need_update) {
+    update_message_count_by_index(d, +1, message.get());
+  }
+  if (auto_attach && message_id.get() > d->last_message_id.get() && message_id.get() >= d->last_new_message_id.get()) {
+    set_dialog_last_message_id(d, message_id, "add_message_to_dialog");
+    *need_update_dialog_pos = true;
+  }
+  if (auto_attach && !message_id.is_yet_unsent() && message_id.get() >= d->last_new_message_id.get() &&
+      (d->last_new_message_id.is_valid() || (message_id.is_local() && message_id.get() >= d->last_message_id.get()))) {
+    CHECK(message_id.get() <= d->last_message_id.get());
+    if (message_id.get() > d->last_database_message_id.get()) {
+      set_dialog_last_database_message_id(d, message_id, "add_message_to_dialog");
+      if (!d->first_database_message_id.is_valid()) {
+        set_dialog_first_database_message_id(d, message_id, "add_message_to_dialog");
+        try_restore_dialog_reply_markup(d, message.get());
+      }
+      on_dialog_updated(dialog_id, "update_last_database_message_id");
+    }
+  }
+  if (!message->from_database && !message_id.is_yet_unsent()) {
+    add_message_to_database(d, message.get(), "add_message_to_dialog");
+  }
+
+  if (!is_attached && !message->have_next && !message->have_previous) {
+    MessagesIterator it(d, message_id);
+    if (*it != nullptr && (*it)->have_next) {
+      // need to drop a connection between messages
+      auto previous_message = *it;
+      ++it;
+      auto next_message = *it;
+      if (next_message != nullptr) {
+        if (next_message->message_id.is_server() &&
+            !(td_->auth_manager_->is_bot() && Slice(source) == Slice("get channel messages"))) {
+          LOG(ERROR) << "Can't attach " << message_id << " from " << source << " before " << next_message->message_id
+                     << " and after " << previous_message->message_id << " in " << dialog_id;
+          dump_debug_message_op(d);
+        }
+
+        next_message->have_previous = false;
+        previous_message->have_next = false;
+      } else {
+        LOG(ERROR) << "Have_next is true, but there is no next message after " << previous_message->message_id
+                   << " from " << source << " in " << dialog_id;
+        dump_debug_message_op(d);
+      }
+    }
+  }
+
+  if (!td_->auth_manager_->is_bot() && from_update && d->reply_markup_message_id != MessageId() &&
+      message_content_id == MessageChatDeleteUser::ID) {
+    auto deleted_user_id = static_cast<const MessageChatDeleteUser *>(message->content.get())->user_id;
+    if (td_->contacts_manager_->is_user_bot(deleted_user_id)) {
+      const Message *old_message = get_message_force(d, d->reply_markup_message_id);
+      if (old_message == nullptr || old_message->sender_user_id == deleted_user_id) {
+        set_dialog_reply_markup(d, MessageId());
+      }
+    }
+  }
+
+  if (message_content_id == MessageContactRegistered::ID && !d->has_contact_registered_message) {
+    d->has_contact_registered_message = true;
+    on_dialog_updated(dialog_id, "update_has_contact_registered_message");
+  }
+
+  if (from_update && dialog_id.get_type() == DialogType::Channel) {
+    int32 new_participant_count = 0;
+    switch (message_content_id) {
+      case MessageChatAddUsers::ID:
+        new_participant_count =
+            narrow_cast<int32>(static_cast<const MessageChatAddUsers *>(message->content.get())->user_ids.size());
+        break;
+      case MessageChatJoinedByLink::ID:
+        new_participant_count = 1;
+        break;
+      case MessageChatDeleteUser::ID:
+        new_participant_count = -1;
+        break;
+      case MessagePinMessage::ID:
+        td_->contacts_manager_->on_update_channel_pinned_message(
+            dialog_id.get_channel_id(), static_cast<const MessagePinMessage *>(message->content.get())->message_id);
+        break;
+    }
+    if (new_participant_count != 0) {
+      td_->contacts_manager_->speculative_add_channel_participants(dialog_id.get_channel_id(), new_participant_count,
+                                                                   message->sender_user_id == my_user_id);
+    }
+  }
+  if (!td_->auth_manager_->is_bot() && (from_update || message_id.is_yet_unsent()) &&
+      message->forward_info == nullptr && (message->is_outgoing || dialog_id == my_dialog_id)) {
+    switch (message_content_id) {
+      case MessageAnimation::ID:
+        if (dialog_id.get_type() != DialogType::SecretChat) {
+          td_->animations_manager_->add_saved_animation_by_id(get_message_content_file_id(message->content.get()));
+        }
+        break;
+      case MessageSticker::ID:
+        if (dialog_id.get_type() != DialogType::SecretChat) {
+          td_->stickers_manager_->add_recent_sticker_by_id(false, get_message_content_file_id(message->content.get()));
+        }
+        break;
+      case MessageText::ID:
+        update_used_hashtags(dialog_id, message.get());
+        break;
+    }
+  }
+  if (!td_->auth_manager_->is_bot() && from_update && (message->is_outgoing || dialog_id == my_dialog_id) &&
+      dialog_id.get_type() != DialogType::SecretChat) {
+    if (message->via_bot_user_id.is_valid() && message->forward_info == nullptr) {
+      // forwarded game messages can't be distinguished from sent via bot game messages, so increase rating anyway
+      send_closure(G()->top_dialog_manager(), &TopDialogManager::on_dialog_used, TopDialogCategory::BotInline,
+                   DialogId(message->via_bot_user_id), message->date);
+    }
+
+    TopDialogCategory category = TopDialogCategory::Size;
+    switch (dialog_id.get_type()) {
+      case DialogType::User: {
+        if (td_->contacts_manager_->is_user_bot(dialog_id.get_user_id())) {
+          category = TopDialogCategory::BotPM;
+        } else {
+          category = TopDialogCategory::Correspondent;
+        }
+        break;
+      }
+      case DialogType::Chat:
+        category = TopDialogCategory::Group;
+        break;
+      case DialogType::Channel:
+        switch (td_->contacts_manager_->get_channel_type(dialog_id.get_channel_id())) {
+          case ChannelType::Broadcast:
+            category = TopDialogCategory::Channel;
+            break;
+          case ChannelType::Megagroup:
+            category = TopDialogCategory::Group;
+            break;
+          case ChannelType::Unknown:
+            break;
+          default:
+            UNREACHABLE();
+            break;
+        }
+        break;
+      case DialogType::SecretChat:
+      case DialogType::None:
+      default:
+        UNREACHABLE();
+    }
+    if (category != TopDialogCategory::Size) {
+      send_closure(G()->top_dialog_manager(), &TopDialogManager::on_dialog_used, category, dialog_id, message->date);
+    }
+  }
+
+  // TODO function
+  v = &d->messages;
+  while (*v != nullptr && (*v)->random_y >= message->random_y) {
+    if ((*v)->message_id.get() < message_id.get()) {
+      v = &(*v)->right;
+    } else if ((*v)->message_id == message_id) {
+      UNREACHABLE();
+    } else {
+      v = &(*v)->left;
+    }
+  }
+
+  unique_ptr<Message> *left = &message->left;
+  unique_ptr<Message> *right = &message->right;
+
+  unique_ptr<Message> cur = std::move(*v);
+  while (cur != nullptr) {
+    if (cur->message_id.get() < message_id.get()) {
+      *left = std::move(cur);
+      left = &((*left)->right);
+      cur = std::move(*left);
+    } else {
+      *right = std::move(cur);
+      right = &((*right)->left);
+      cur = std::move(*right);
+    }
+  }
+  CHECK(*left == nullptr);
+  CHECK(*right == nullptr);
+  *v = std::move(message);
+
+  CHECK(d->messages != nullptr);
+
+  if (!is_attached) {
+    if ((*v)->have_next) {
+      CHECK(!(*v)->have_previous);
+      attach_message_to_next(d, message_id);
+    } else if ((*v)->have_previous) {
+      attach_message_to_previous(d, message_id);
+    }
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+      message_id_to_dialog_id_[message_id] = dialog_id;
+      break;
+    case DialogType::Channel:
+      // nothing to do
+      break;
+    case DialogType::SecretChat:
+      LOG(INFO) << "Add correspondence random_id " << (*v)->random_id << " to " << message_id << " in " << dialog_id;
+      d->random_id_to_message_id[(*v)->random_id] = message_id;
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+
+  return v->get();
+}
+
+void MessagesManager::on_message_changed(const Dialog *d, const Message *m, const char *source) {
+  CHECK(d != nullptr);
+  CHECK(m != nullptr);
+  if (m->message_id == d->last_message_id) {
+    send_update_chat_last_message_impl(d, source);
+  }
+
+  if (m->message_id == d->last_database_message_id) {
+    on_dialog_updated(d->dialog_id, source);
+  }
+
+  if (!m->message_id.is_yet_unsent()) {
+    add_message_to_database(d, m, source);
+  }
+}
+
+void MessagesManager::add_message_to_database(const Dialog *d, const Message *m, const char *source) {
+  if (!G()->parameters().use_message_db) {
+    return;
+  }
+
+  CHECK(d != nullptr);
+  CHECK(m != nullptr);
+  MessageId message_id = m->message_id;
+  CHECK(message_id.is_server() || message_id.is_local()) << source;
+
+  LOG(INFO) << "Add " << FullMessageId(d->dialog_id, message_id) << " to database from " << source;
+
+  ServerMessageId unique_message_id;
+  int64 random_id = 0;
+  int64 search_id = 0;
+  string text;
+  switch (d->dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+      if (message_id.is_server()) {
+        unique_message_id = message_id.get_server_message_id();
+      }
+      //FOR DEBUG
+      //text = get_search_text(m);
+      //if (!text.empty()) {
+      //search_id = (static_cast<int64>(m->date) << 32) | static_cast<uint32>(Random::secure_int32());
+      //}
+      break;
+    case DialogType::Channel:
+      break;
+    case DialogType::SecretChat:
+      random_id = m->random_id;
+      text = get_search_text(m);
+      if (!text.empty()) {
+        search_id = (static_cast<int64>(m->date) << 32) | static_cast<uint32>(m->random_id);
+      }
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+
+  int32 ttl_expires_at = 0;
+  if (m->ttl_expires_at != 0) {
+    ttl_expires_at = static_cast<int32>(m->ttl_expires_at - Time::now() + G()->server_time());
+  }
+  G()->td_db()->get_messages_db_async()->add_message({d->dialog_id, message_id}, unique_message_id, m->sender_user_id,
+                                                     random_id, ttl_expires_at, get_message_index_mask(d->dialog_id, m),
+                                                     search_id, text, log_event_store(*m), Auto());  // TODO Promise
+}
+
+void MessagesManager::delete_all_dialog_messages_from_database(DialogId dialog_id, MessageId message_id,
+                                                               const char *source) {
+  if (!G()->parameters().use_message_db) {
+    return;
+  }
+
+  CHECK(dialog_id.is_valid());
+  if (!message_id.is_valid()) {
+    return;
+  }
+
+  LOG(INFO) << "Delete all messages in " << dialog_id << " from database up to " << message_id << " from " << source;
+  /*
+  if (dialog_id.get_type() == DialogType::User && message_id.is_server()) {
+    bool need_save = false;
+    int i = 0;
+    for (auto &first_message_id : calls_db_state_.first_calls_database_message_id_by_index) {
+      if (first_message_id.get() <= message_id.get()) {
+        first_message_id = message_id.get_next_server_message_id();
+        calls_db_state_.message_count_by_index[i] = -1;
+        need_save = true;
+      }
+      i++;
+    }
+    if (need_save) {
+      save_calls_db_state();
+    }
+  }
+*/
+  G()->td_db()->get_messages_db_async()->delete_all_dialog_messages(dialog_id, message_id, Auto());  // TODO Promise
+}
+
+class MessagesManager::DeleteMessageLogEvent {
+ public:
+  LogEvent::Id id_{0};
+  FullMessageId full_message_id_;
+  std::vector<FileId> file_ids_;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    bool has_file_ids = !file_ids_.empty();
+    BEGIN_STORE_FLAGS();
+    STORE_FLAG(has_file_ids);
+    END_STORE_FLAGS();
+
+    td::store(full_message_id_, storer);
+    if (has_file_ids) {
+      td::store(file_ids_, storer);
+    }
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    bool has_file_ids;
+    BEGIN_PARSE_FLAGS();
+    PARSE_FLAG(has_file_ids);
+    END_PARSE_FLAGS();
+
+    td::parse(full_message_id_, parser);
+    if (has_file_ids) {
+      td::parse(file_ids_, parser);
+    }
+  }
+};
+
+void MessagesManager::delete_message_files(const Message *m) const {
+  for (auto file_id : get_message_file_ids(m)) {
+    send_closure(G()->file_manager(), &FileManager::delete_file, file_id, Promise<>(),
+                 "delete_message_files");  // TODO add log event
+  }
+}
+
+void MessagesManager::delete_message_from_database(Dialog *d, MessageId message_id, const Message *m,
+                                                   bool is_permanently_deleted) const {
+  if (is_permanently_deleted) {
+    d->deleted_message_ids.insert(message_id);
+  }
+
+  if (message_id.is_yet_unsent()) {
+    return;
+  }
+
+  auto is_secret = d->dialog_id.get_type() == DialogType::SecretChat;
+  if (m != nullptr && m->ttl > 0) {
+    delete_message_files(m);
+  }
+
+  if (!G()->parameters().use_message_db) {
+    // TODO message files should be deleted anyway
+    // TODO message should be deleted anyway after restart
+    return;
+  }
+
+  DeleteMessageLogEvent logevent;
+
+  logevent.full_message_id_ = {d->dialog_id, message_id};
+
+  if (is_secret && m != nullptr) {
+    logevent.file_ids_ = get_message_file_ids(m);
+  }
+
+  do_delete_message_logevent(logevent);
+}
+
+void MessagesManager::do_delete_message_logevent(const DeleteMessageLogEvent &logevent) const {
+  Promise<Unit> db_promise;
+  if (!logevent.file_ids_.empty()) {
+    auto logevent_id = logevent.id_;
+    if (!logevent_id) {
+      auto storer = LogEventStorerImpl<DeleteMessageLogEvent>(logevent);
+      logevent_id = BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::DeleteMessage, storer);
+    }
+
+    MultiPromiseActorSafe mpas;
+    mpas.add_promise(PromiseCreator::lambda([logevent_id](Result<Unit> result) {
+      if (result.is_error()) {
+        return;
+      }
+      BinlogHelper::erase(G()->td_db()->get_binlog(), logevent_id);
+    }));
+
+    auto lock = mpas.get_promise();
+    for (auto file_id : logevent.file_ids_) {
+      send_closure(G()->file_manager(), &FileManager::delete_file, file_id, mpas.get_promise(),
+                   "do_delete_message_logevent");
+    }
+    db_promise = mpas.get_promise();
+    lock.set_value(Unit());
+  }
+
+  // message may not exist in the dialog
+  LOG(INFO) << "Delete " << logevent.full_message_id_ << " from database";
+  G()->td_db()->get_messages_db_async()->delete_message(logevent.full_message_id_, std::move(db_promise));
+}
+
+void MessagesManager::attach_message_to_previous(Dialog *d, MessageId message_id) {
+  CHECK(d != nullptr);
+  MessagesIterator it(d, message_id);
+  Message *message = *it;
+  CHECK(message != nullptr);
+  CHECK(message->message_id == message_id);
+  CHECK(message->have_previous);
+  --it;
+  CHECK(*it != nullptr);
+  LOG(INFO) << "Attach " << message_id << " to the previous " << (*it)->message_id;
+  if ((*it)->have_next) {
+    message->have_next = true;
+  } else {
+    (*it)->have_next = true;
+  }
+}
+
+void MessagesManager::attach_message_to_next(Dialog *d, MessageId message_id) {
+  CHECK(d != nullptr);
+  MessagesIterator it(d, message_id);
+  Message *message = *it;
+  CHECK(message != nullptr);
+  CHECK(message->message_id == message_id);
+  CHECK(message->have_next);
+  ++it;
+  CHECK(*it != nullptr);
+  LOG(INFO) << "Attach " << message_id << " to the next " << (*it)->message_id;
+  if ((*it)->have_previous) {
+    message->have_previous = true;
+  } else {
+    (*it)->have_previous = true;
+  }
+}
+
+void MessagesManager::update_message(Dialog *d, unique_ptr<Message> &old_message, unique_ptr<Message> new_message,
+                                     bool need_send_update_message_content, bool *need_update_dialog_pos) {
+  CHECK(d != nullptr);
+  CHECK(old_message != nullptr);
+  CHECK(new_message != nullptr);
+  CHECK(old_message->message_id == new_message->message_id);
+  CHECK(old_message->random_y == new_message->random_y);
+  CHECK(need_update_dialog_pos != nullptr);
+
+  DialogId dialog_id = d->dialog_id;
+  MessageId message_id = old_message->message_id;
+  bool is_changed = false;
+  if (old_message->date != new_message->date) {
+    if (new_message->date > 0) {
+      LOG_IF(ERROR,
+             !new_message->is_outgoing && dialog_id != DialogId(td_->contacts_manager_->get_my_id("update_message")))
+          << "Date has changed for incoming " << message_id << " in " << dialog_id << " from " << old_message->date
+          << " to " << new_message->date;
+      CHECK(old_message->date > 0);
+      old_message->date = new_message->date;
+      if (d->last_message_id == message_id) {
+        *need_update_dialog_pos = true;
+      }
+      is_changed = true;
+    } else {
+      LOG(ERROR) << "Receive " << message_id << " in " << dialog_id << " with wrong date " << new_message->date;
+    }
+  }
+  bool is_edited = false;
+  if (old_message->edit_date != new_message->edit_date) {
+    if (new_message->edit_date > 0) {
+      if (new_message->edit_date > old_message->edit_date) {
+        old_message->edit_date = new_message->edit_date;
+        is_edited = true;
+        is_changed = true;
+      }
+    } else {
+      LOG(ERROR) << "Receive " << message_id << " in " << dialog_id << " with wrong edit date "
+                 << new_message->edit_date << ", old edit date = " << old_message->edit_date;
+    }
+  }
+
+  if (old_message->author_signature != new_message->author_signature) {
+    LOG_IF(INFO, !old_message->sender_user_id.is_valid() || new_message->sender_user_id.is_valid())
+        << "Author signature has changed for " << message_id << " in " << dialog_id << " sent by "
+        << old_message->sender_user_id << "/" << new_message->sender_user_id << " from "
+        << old_message->author_signature << " to " << new_message->author_signature;
+    old_message->author_signature = std::move(new_message->author_signature);
+    is_changed = true;
+  }
+  if (old_message->sender_user_id != new_message->sender_user_id) {
+    // there can be race for sent signed posts
+    LOG_IF(ERROR, old_message->sender_user_id != UserId() && new_message->sender_user_id != UserId())
+        << message_id << " in " << dialog_id << " has changed sender from " << old_message->sender_user_id << " to "
+        << new_message->sender_user_id;
+
+    LOG_IF(WARNING, new_message->sender_user_id.is_valid() || old_message->author_signature.empty())
+        << "Update message sender from " << old_message->sender_user_id << " to " << new_message->sender_user_id
+        << " in " << dialog_id;
+    old_message->sender_user_id = new_message->sender_user_id;
+    is_changed = true;
+  }
+  if (old_message->forward_info == nullptr) {
+    if (new_message->forward_info != nullptr) {
+      LOG(ERROR) << message_id << " in " << dialog_id << " has received forward info " << *new_message->forward_info;
+    }
+  } else {
+    if (new_message->forward_info != nullptr) {
+      if (*old_message->forward_info != *new_message->forward_info &&
+          (!old_message->forward_info->sender_user_id.is_valid() ||
+           new_message->forward_info->sender_user_id.is_valid())) {
+        old_message->forward_info->author_signature = new_message->forward_info->author_signature;
+        LOG_IF(ERROR, *old_message->forward_info != *new_message->forward_info)
+            << message_id << " in " << dialog_id << " has changed forward info from " << *old_message->forward_info
+            << " to " << *new_message->forward_info << ", really forwarded from " << old_message->debug_forward_from;
+      }
+      old_message->forward_info = std::move(new_message->forward_info);
+      is_changed = true;
+    } else {
+      LOG(ERROR) << message_id << " in " << dialog_id << " sent by " << old_message->sender_user_id
+                 << " has lost forward info " << *old_message->forward_info << ", really forwarded from "
+                 << old_message->debug_forward_from;
+      old_message->forward_info = nullptr;
+      is_changed = true;
+    }
+  }
+
+  if (old_message->reply_to_message_id != new_message->reply_to_message_id) {
+    if (new_message->reply_to_message_id == MessageId() &&
+        get_message_force(d, old_message->reply_to_message_id) == nullptr) {
+      old_message->reply_to_message_id = MessageId();
+      is_changed = true;
+    } else {
+      LOG(ERROR) << message_id << " in " << dialog_id << " has changed message it is reply to from "
+                 << old_message->reply_to_message_id << " to " << new_message->reply_to_message_id;
+      dump_debug_message_op(d);
+    }
+  }
+  LOG_IF(ERROR, old_message->via_bot_user_id != new_message->via_bot_user_id)
+      << message_id << " in " << dialog_id << " has changed bot via it is sent from " << old_message->via_bot_user_id
+      << " to " << new_message->via_bot_user_id;
+  LOG_IF(ERROR, old_message->is_outgoing != new_message->is_outgoing)
+      << message_id << " in " << dialog_id << " has changed is_outgoing from " << old_message->is_outgoing << " to "
+      << new_message->is_outgoing;
+  LOG_IF(ERROR, old_message->is_channel_post != new_message->is_channel_post)
+      << message_id << " in " << dialog_id << " has changed is_channel_post from " << old_message->is_channel_post
+      << " to " << new_message->is_channel_post;
+  LOG_IF(ERROR, old_message->contains_mention != new_message->contains_mention && old_message->edit_date == 0)
+      << message_id << " in " << dialog_id << " has changed contains_mention from " << old_message->contains_mention
+      << " to " << new_message->contains_mention;
+  LOG_IF(ERROR, old_message->disable_notification != new_message->disable_notification && old_message->edit_date == 0)
+      << "Disable_notification has changed from " << old_message->disable_notification << " to "
+      << new_message->disable_notification
+      << ". Old message: " << to_string(get_message_object(dialog_id, old_message.get()))
+      << ". New message: " << to_string(get_message_object(dialog_id, new_message.get()));
+
+  if (update_message_contains_unread_mention(d, old_message.get(), new_message->contains_unread_mention,
+                                             "update_message")) {
+    is_changed = true;
+  }
+  if (update_message_views(dialog_id, old_message.get(), new_message->views)) {
+    is_changed = true;
+  }
+  if ((old_message->media_album_id == 0 || td_->auth_manager_->is_bot()) && new_message->media_album_id != 0) {
+    old_message->media_album_id = new_message->media_album_id;
+    is_changed = true;
+  }
+
+  if (old_message->edit_date > 0) {
+    // inline keyboard can be edited
+    bool reply_markup_changed =
+        ((old_message->reply_markup == nullptr) != (new_message->reply_markup == nullptr)) ||
+        (old_message->reply_markup != nullptr && *old_message->reply_markup != *new_message->reply_markup);
+    if (reply_markup_changed) {
+      if (d->reply_markup_message_id == message_id && !td_->auth_manager_->is_bot() &&
+          new_message->reply_markup == nullptr) {
+        set_dialog_reply_markup(d, MessageId());
+      }
+      old_message->reply_markup = std::move(new_message->reply_markup);
+      is_edited = true;
+      is_changed = true;
+    }
+    old_message->had_reply_markup = false;
+  } else {
+    if (old_message->reply_markup == nullptr) {
+      if (new_message->reply_markup != nullptr) {
+        auto content_type = old_message->content->get_id();
+        // MessageGame and MessageInvoice reply markup can be generated server side
+        LOG_IF(ERROR, content_type != MessageGame::ID && content_type != MessageInvoice::ID)
+            << message_id << " in " << dialog_id << " has received reply markup " << *new_message->reply_markup;
+
+        old_message->had_reply_markup = false;
+        old_message->reply_markup = std::move(new_message->reply_markup);
+        is_changed = true;
+      }
+    } else {
+      if (new_message->reply_markup != nullptr) {
+        LOG_IF(WARNING, *old_message->reply_markup != *new_message->reply_markup)
+            << message_id << " in " << dialog_id << " has changed reply_markup from " << *old_message->reply_markup
+            << " to " << *new_message->reply_markup;
+      } else {
+        LOG(ERROR) << message_id << " in " << dialog_id << " sent by " << old_message->sender_user_id
+                   << " has lost reply markup " << *old_message->reply_markup;
+      }
+    }
+  }
+
+  if (old_message->last_access_date < new_message->last_access_date) {
+    old_message->last_access_date = new_message->last_access_date;
+  }
+
+  CHECK(!new_message->have_previous || !new_message->have_next);
+  if (new_message->have_previous && !old_message->have_previous) {
+    old_message->have_previous = true;
+    attach_message_to_previous(d, message_id);
+  } else if (new_message->have_next && !old_message->have_next) {
+    old_message->have_next = true;
+    attach_message_to_next(d, message_id);
+  }
+
+  if (update_message_content(dialog_id, old_message.get(), old_message->content, std::move(new_message->content),
+                             need_send_update_message_content)) {
+    is_changed = true;
+  }
+  // TODO update can be send only if the message has already been returned to the user
+  if (is_edited && !td_->auth_manager_->is_bot()) {
+    send_update_message_edited(dialog_id, old_message.get());
+  }
+
+  (void)is_changed;
+  // need to save message always, because it might be added to some message index
+  // if (is_changed) {
+  on_message_changed(d, old_message.get(), "update_message");
+  // }
+}
+
+bool MessagesManager::need_message_text_changed_warning(const Message *old_message, const MessageText *old_content,
+                                                        const MessageText *new_content) {
+  if (old_message->edit_date > 0) {
+    // message was edited
+    return false;
+  }
+  if (old_message->message_id.is_yet_unsent() && old_message->forward_info != nullptr) {
+    // original message may be edited
+    return false;
+  }
+  if (new_content->text.text == "Unsupported characters" ||
+      new_content->text.text == "This channel is blocked because it was used to spread pornographic content.") {
+    // message contained unsupported characters, text is replaced
+    return false;
+  }
+  if (old_message->message_id.is_yet_unsent() && !old_content->text.entities.empty() &&
+      old_content->text.entities[0].offset == 0 &&
+      (new_content->text.entities.empty() || new_content->text.entities[0].offset != 0) &&
+      old_content->text.text != new_content->text.text && ends_with(old_content->text.text, new_content->text.text)) {
+    // server has deleted first entity and ltrim the message
+    return false;
+  }
+  for (auto &entity : new_content->text.entities) {
+    if (entity.type == MessageEntity::Type::PhoneNumber) {
+      // TODO remove after find_phone_numbers is implemented
+      return false;
+    }
+  }
+  return true;
+}
+
+bool MessagesManager::update_message_content(DialogId dialog_id, Message *old_message,
+                                             unique_ptr<MessageContent> &old_content,
+                                             unique_ptr<MessageContent> new_content,
+                                             bool need_send_update_message_content) {
+  bool is_content_changed = false;
+  bool need_update = false;
+  int32 old_content_type = old_content->get_id();
+  int32 new_content_type = new_content->get_id();
+  bool can_delete_old_document = old_message->message_id.is_yet_unsent() && false;
+
+  if (old_content_type != new_content_type) {
+    need_update = true;
+    LOG(INFO) << "Message content has changed its type from " << old_content_type << " to " << new_content_type;
+
+    old_message->is_content_secret = is_secret_message_content(old_message->ttl, new_content->get_id());
+
+    auto old_file_id = get_message_content_file_id(old_content.get());
+    if (old_file_id.is_valid()) {
+      // cancel file upload of the main file to allow next upload with the same file to succeed
+      td_->file_manager_->upload(old_file_id, nullptr, 0, 0);
+
+      auto new_file_id = get_message_content_file_id(new_content.get());
+      if (new_file_id.is_valid()) {
+        FileView old_file_view = td_->file_manager_->get_file_view(old_file_id);
+        FileView new_file_view = td_->file_manager_->get_file_view(new_file_id);
+        // if file type has changed, but file size remains the same, we are trying to update local location of the new
+        // file with the old local location
+        if (old_file_view.has_local_location() && !new_file_view.has_local_location() && old_file_view.size() != 0 &&
+            old_file_view.size() == new_file_view.size()) {
+          auto old_file_type = old_file_view.get_type();
+          auto new_file_type = new_file_view.get_type();
+          auto is_document_file_type = [](FileType file_type) {
+            switch (file_type) {
+              case FileType::Video:
+              case FileType::VoiceNote:
+              case FileType::Document:
+              case FileType::Sticker:
+              case FileType::Audio:
+              case FileType::Animation:
+              case FileType::VideoNote:
+                return true;
+              default:
+                return false;
+            }
+          };
+
+          if (is_document_file_type(old_file_type) && is_document_file_type(new_file_type)) {
+            auto &old_location = old_file_view.local_location();
+            auto r_file_id = td_->file_manager_->register_local(
+                FullLocalFileLocation(new_file_type, old_location.path_, old_location.mtime_nsec_), dialog_id,
+                old_file_view.size());
+            if (r_file_id.is_ok()) {
+              LOG_STATUS(td_->file_manager_->merge(new_file_id, r_file_id.ok()));
+            }
+          }
+        }
+      }
+    }
+  } else {
+    switch (new_content_type) {
+      case MessageText::ID: {
+        auto old_ = static_cast<const MessageText *>(old_content.get());
+        auto new_ = static_cast<const MessageText *>(new_content.get());
+        if (old_->text.text != new_->text.text) {
+          if (need_message_text_changed_warning(old_message, old_, new_)) {
+            LOG(ERROR) << "Message text has changed for " << to_string(get_message_object(dialog_id, old_message))
+                       << ". New content is "
+                       << to_string(get_message_content_object(new_content.get(), old_message->date,
+                                                               old_message->is_content_secret));
+          }
+          need_update = true;
+        }
+        if (old_->text.entities != new_->text.entities) {
+          const int32 MAX_CUSTOM_ENTITIES_COUNT = 100;  // server-size limit
+          if (need_message_text_changed_warning(old_message, old_, new_) &&
+              old_->text.entities.size() <= MAX_CUSTOM_ENTITIES_COUNT) {
+            LOG(WARNING) << "Entities has changed for " << to_string(get_message_object(dialog_id, old_message))
+                         << ". New content is "
+                         << to_string(get_message_content_object(new_content.get(), old_message->date,
+                                                                 old_message->is_content_secret));
+          }
+          need_update = true;
+        }
+        if (old_->web_page_id != new_->web_page_id) {
+          LOG(INFO) << "Old: " << old_->web_page_id << ", new: " << new_->web_page_id;
+          is_content_changed = true;
+          need_update |= td_->web_pages_manager_->have_web_page(old_->web_page_id) ||
+                         td_->web_pages_manager_->have_web_page(new_->web_page_id);
+        }
+        break;
+      }
+      case MessageAnimation::ID: {
+        auto old_ = static_cast<const MessageAnimation *>(old_content.get());
+        auto new_ = static_cast<const MessageAnimation *>(new_content.get());
+        if (td_->animations_manager_->merge_animations(new_->file_id, old_->file_id, can_delete_old_document)) {
+          need_update = true;
+        }
+        if (old_->caption != new_->caption) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageAudio::ID: {
+        auto old_ = static_cast<const MessageAudio *>(old_content.get());
+        auto new_ = static_cast<const MessageAudio *>(new_content.get());
+        if (td_->audios_manager_->merge_audios(new_->file_id, old_->file_id, can_delete_old_document)) {
+          need_update = true;
+        }
+        if (old_->caption != new_->caption) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageContact::ID: {
+        auto old_ = static_cast<const MessageContact *>(old_content.get());
+        auto new_ = static_cast<const MessageContact *>(new_content.get());
+        if (old_->contact != new_->contact) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageDocument::ID: {
+        auto old_ = static_cast<const MessageDocument *>(old_content.get());
+        auto new_ = static_cast<const MessageDocument *>(new_content.get());
+        if (td_->documents_manager_->merge_documents(new_->file_id, old_->file_id, can_delete_old_document)) {
+          need_update = true;
+        }
+        if (old_->caption != new_->caption) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageGame::ID: {
+        auto old_ = static_cast<const MessageGame *>(old_content.get());
+        auto new_ = static_cast<const MessageGame *>(new_content.get());
+        if (old_->game != new_->game) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageInvoice::ID: {
+        auto old_ = static_cast<const MessageInvoice *>(old_content.get());
+        auto new_ = static_cast<const MessageInvoice *>(new_content.get());
+        if (old_->title != new_->title || old_->description != new_->description || old_->photo != new_->photo ||
+            old_->start_parameter != new_->start_parameter || old_->invoice != new_->invoice ||
+            old_->total_amount != new_->total_amount || old_->receipt_message_id != new_->receipt_message_id) {
+          need_update = true;
+        }
+        if (old_->payload != new_->payload || old_->provider_token != new_->provider_token ||
+            old_->provider_data != new_->provider_data) {
+          is_content_changed = true;
+        }
+        break;
+      }
+      case MessageLiveLocation::ID: {
+        auto old_ = static_cast<const MessageLiveLocation *>(old_content.get());
+        auto new_ = static_cast<const MessageLiveLocation *>(new_content.get());
+        if (old_->location != new_->location) {
+          need_update = true;
+        }
+        if (old_->period != new_->period) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageLocation::ID: {
+        auto old_ = static_cast<const MessageLocation *>(old_content.get());
+        auto new_ = static_cast<const MessageLocation *>(new_content.get());
+        if (old_->location != new_->location) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessagePhoto::ID: {
+        auto old_ = static_cast<const MessagePhoto *>(old_content.get());
+        auto new_ = static_cast<MessagePhoto *>(new_content.get());
+        const Photo *old_photo = &old_->photo;
+        Photo *new_photo = &new_->photo;
+        if (old_photo->date != new_photo->date) {
+          is_content_changed = true;
+        }
+        if (old_photo->id != new_photo->id || old_->caption != new_->caption) {
+          need_update = true;
+        }
+        if (old_photo->photos != new_photo->photos) {
+          if ((old_photo->photos.size() == 1 || (old_photo->photos.size() == 2 && old_photo->photos[0].type == 't')) &&
+              old_photo->photos.back().type == 'i' && new_photo->photos.size() > 0) {
+            // first time get info about sent photo
+            if (old_photo->photos.size() == 2) {
+              new_photo->photos.push_back(old_photo->photos[0]);
+            }
+            new_photo->photos.push_back(old_photo->photos.back());
+            FileId old_file_id = old_photo->photos.back().file_id;
+            FileView old_file_view = td_->file_manager_->get_file_view(old_file_id);
+            FileId new_file_id = new_photo->photos[0].file_id;
+            FileView new_file_view = td_->file_manager_->get_file_view(new_file_id);
+            if (!old_file_view.has_remote_location()) {
+              CHECK(new_file_view.has_remote_location());
+              CHECK(!new_file_view.remote_location().is_web());
+              FileId file_id = td_->file_manager_->register_remote(
+                  FullRemoteFileLocation(FileType::Photo, new_file_view.remote_location().get_id(),
+                                         new_file_view.remote_location().get_access_hash(), 0, 0, 0, DcId::invalid()),
+                  FileLocationSource::FromServer, dialog_id, old_photo->photos.back().size, 0, "");
+              LOG_STATUS(td_->file_manager_->merge(file_id, old_file_id));
+            }
+          }
+          if ((old_photo->photos.size() == 1 + new_photo->photos.size() ||
+               (old_photo->photos.size() == 2 + new_photo->photos.size() &&
+                old_photo->photos[new_photo->photos.size()].type == 't')) &&
+              old_photo->photos.back().type == 'i') {
+            // get sent photo again
+            if (old_photo->photos.size() == 2 + new_photo->photos.size()) {
+              new_photo->photos.push_back(old_photo->photos[new_photo->photos.size()]);
+            }
+            new_photo->photos.push_back(old_photo->photos.back());
+          }
+          if (old_photo->photos != new_photo->photos) {
+            need_update = true;
+          }
+        }
+        break;
+      }
+      case MessageSticker::ID: {
+        auto old_ = static_cast<const MessageSticker *>(old_content.get());
+        auto new_ = static_cast<const MessageSticker *>(new_content.get());
+        if (td_->stickers_manager_->merge_stickers(new_->file_id, old_->file_id, can_delete_old_document)) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageVenue::ID: {
+        auto old_ = static_cast<const MessageVenue *>(old_content.get());
+        auto new_ = static_cast<const MessageVenue *>(new_content.get());
+        if (old_->venue != new_->venue) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageVideo::ID: {
+        auto old_ = static_cast<const MessageVideo *>(old_content.get());
+        auto new_ = static_cast<const MessageVideo *>(new_content.get());
+        if (td_->videos_manager_->merge_videos(new_->file_id, old_->file_id, can_delete_old_document)) {
+          need_update = true;
+        }
+        if (old_->caption != new_->caption) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageVideoNote::ID: {
+        auto old_ = static_cast<const MessageVideoNote *>(old_content.get());
+        auto new_ = static_cast<const MessageVideoNote *>(new_content.get());
+        if (td_->video_notes_manager_->merge_video_notes(new_->file_id, old_->file_id, can_delete_old_document)) {
+          need_update = true;
+        }
+        if (old_->is_viewed != new_->is_viewed) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageVoiceNote::ID: {
+        auto old_ = static_cast<const MessageVoiceNote *>(old_content.get());
+        auto new_ = static_cast<const MessageVoiceNote *>(new_content.get());
+        if (td_->voice_notes_manager_->merge_voice_notes(new_->file_id, old_->file_id, can_delete_old_document)) {
+          need_update = true;
+        }
+        if (old_->caption != new_->caption) {
+          need_update = true;
+        }
+        if (old_->is_listened != new_->is_listened) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageChatCreate::ID: {
+        auto old_ = static_cast<const MessageChatCreate *>(old_content.get());
+        auto new_ = static_cast<const MessageChatCreate *>(new_content.get());
+        if (old_->title != new_->title || old_->participant_user_ids != new_->participant_user_ids) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageChatChangeTitle::ID: {
+        auto old_ = static_cast<const MessageChatChangeTitle *>(old_content.get());
+        auto new_ = static_cast<const MessageChatChangeTitle *>(new_content.get());
+        if (old_->title != new_->title) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageChatChangePhoto::ID: {
+        auto old_ = static_cast<const MessageChatChangePhoto *>(old_content.get());
+        auto new_ = static_cast<const MessageChatChangePhoto *>(new_content.get());
+        if (old_->photo != new_->photo) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageChatDeletePhoto::ID:
+        break;
+      case MessageChatDeleteHistory::ID:
+        break;
+      case MessageChatAddUsers::ID: {
+        auto old_ = static_cast<const MessageChatAddUsers *>(old_content.get());
+        auto new_ = static_cast<const MessageChatAddUsers *>(new_content.get());
+        if (old_->user_ids != new_->user_ids) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageChatJoinedByLink::ID:
+        break;
+      case MessageChatDeleteUser::ID: {
+        auto old_ = static_cast<const MessageChatDeleteUser *>(old_content.get());
+        auto new_ = static_cast<const MessageChatDeleteUser *>(new_content.get());
+        if (old_->user_id != new_->user_id) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageChatMigrateTo::ID: {
+        auto old_ = static_cast<const MessageChatMigrateTo *>(old_content.get());
+        auto new_ = static_cast<const MessageChatMigrateTo *>(new_content.get());
+        if (old_->migrated_to_channel_id != new_->migrated_to_channel_id) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageChannelCreate::ID: {
+        auto old_ = static_cast<const MessageChannelCreate *>(old_content.get());
+        auto new_ = static_cast<const MessageChannelCreate *>(new_content.get());
+        if (old_->title != new_->title) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageChannelMigrateFrom::ID: {
+        auto old_ = static_cast<const MessageChannelMigrateFrom *>(old_content.get());
+        auto new_ = static_cast<const MessageChannelMigrateFrom *>(new_content.get());
+        if (old_->title != new_->title || old_->migrated_from_chat_id != new_->migrated_from_chat_id) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessagePinMessage::ID: {
+        auto old_ = static_cast<const MessagePinMessage *>(old_content.get());
+        auto new_ = static_cast<const MessagePinMessage *>(new_content.get());
+        if (old_->message_id != new_->message_id) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageGameScore::ID: {
+        auto old_ = static_cast<const MessageGameScore *>(old_content.get());
+        auto new_ = static_cast<const MessageGameScore *>(new_content.get());
+        if (old_->game_message_id != new_->game_message_id || old_->game_id != new_->game_id ||
+            old_->score != new_->score) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageScreenshotTaken::ID:
+        break;
+      case MessageChatSetTtl::ID: {
+        auto old_ = static_cast<const MessageChatSetTtl *>(old_content.get());
+        auto new_ = static_cast<const MessageChatSetTtl *>(new_content.get());
+        if (old_->ttl != new_->ttl) {
+          LOG(ERROR) << "Ttl has changed from " << old_->ttl << " to " << new_->ttl;
+          need_update = true;
+        }
+        break;
+      }
+      case MessageCall::ID: {
+        auto old_ = static_cast<const MessageCall *>(old_content.get());
+        auto new_ = static_cast<const MessageCall *>(new_content.get());
+        if (old_->call_id != new_->call_id) {
+          is_content_changed = true;
+        }
+        if (old_->duration != new_->duration || old_->discard_reason != new_->discard_reason) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessagePaymentSuccessful::ID: {
+        auto old_ = static_cast<const MessagePaymentSuccessful *>(old_content.get());
+        auto new_ = static_cast<const MessagePaymentSuccessful *>(new_content.get());
+        if (old_->invoice_message_id != new_->invoice_message_id || old_->currency != new_->currency ||
+            old_->total_amount != new_->total_amount || old_->invoice_payload != new_->invoice_payload ||
+            old_->shipping_option_id != new_->shipping_option_id ||
+            old_->telegram_payment_charge_id != new_->telegram_payment_charge_id ||
+            old_->provider_payment_charge_id != new_->provider_payment_charge_id ||
+            ((old_->order_info != nullptr || new_->order_info != nullptr) &&
+             (old_->order_info == nullptr || new_->order_info == nullptr || *old_->order_info != *new_->order_info))) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageContactRegistered::ID:
+        break;
+      case MessageExpiredPhoto::ID:
+        break;
+      case MessageExpiredVideo::ID:
+        break;
+      case MessageCustomServiceAction::ID: {
+        auto old_ = static_cast<const MessageCustomServiceAction *>(old_content.get());
+        auto new_ = static_cast<const MessageCustomServiceAction *>(new_content.get());
+        if (old_->message != new_->message) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageWebsiteConnected::ID: {
+        auto old_ = static_cast<const MessageWebsiteConnected *>(old_content.get());
+        auto new_ = static_cast<const MessageWebsiteConnected *>(new_content.get());
+        if (old_->domain_name != new_->domain_name) {
+          need_update = true;
+        }
+        break;
+      }
+      case MessageUnsupported::ID:
+        break;
+      default:
+        UNREACHABLE();
+        break;
+    }
+  }
+
+  if (is_content_changed || need_update) {
+    auto old_file_id = get_message_content_file_id(old_content.get());
+    old_content = std::move(new_content);
+    update_message_content_file_id_remote(old_content.get(), old_file_id);
+  } else {
+    update_message_content_file_id_remote(old_content.get(), get_message_content_file_id(new_content.get()));
+  }
+  if (is_content_changed && !need_update) {
+    LOG(INFO) << "Content of " << old_message->message_id << " in " << dialog_id << " has changed";
+  }
+
+  if (need_update && need_send_update_message_content) {
+    send_update_message_content(dialog_id, old_message->message_id, old_content.get(), old_message->date,
+                                old_message->is_content_secret, "update_message_content");
+  }
+  return is_content_changed || need_update;
+}
+
+MessagesManager::Dialog *MessagesManager::get_dialog_by_message_id(MessageId message_id) {
+  CHECK(message_id.is_valid() && message_id.is_server());
+  auto it = message_id_to_dialog_id_.find(message_id);
+  if (it == message_id_to_dialog_id_.end()) {
+    if (G()->parameters().use_message_db) {
+      auto r_value =
+          G()->td_db()->get_messages_db_sync()->get_message_by_unique_message_id(message_id.get_server_message_id());
+      if (r_value.is_ok()) {
+        DialogId dialog_id(r_value.ok().first);
+        Message *m = on_get_message_from_database(dialog_id, get_dialog_force(dialog_id), r_value.ok().second);
+        if (m != nullptr) {
+          CHECK(m->message_id == message_id);
+          CHECK(message_id_to_dialog_id_[message_id] == dialog_id);
+          Dialog *d = get_dialog(dialog_id);
+          CHECK(d != nullptr);
+          return d;
+        }
+      }
+    }
+
+    return nullptr;
+  }
+
+  return get_dialog(it->second);
+}
+
+MessageId MessagesManager::get_message_id_by_random_id(Dialog *d, int64 random_id) {
+  CHECK(d != nullptr);
+  CHECK(d->dialog_id.get_type() == DialogType::SecretChat);
+  if (random_id == 0) {
+    return MessageId();
+  }
+  auto it = d->random_id_to_message_id.find(random_id);
+  if (it == d->random_id_to_message_id.end()) {
+    if (G()->parameters().use_message_db) {
+      auto r_value = G()->td_db()->get_messages_db_sync()->get_message_by_random_id(d->dialog_id, random_id);
+      if (r_value.is_ok()) {
+        Message *m = on_get_message_from_database(d->dialog_id, d, r_value.ok());
+        if (m != nullptr) {
+          CHECK(m->random_id == random_id);
+          CHECK(d->random_id_to_message_id[random_id] == m->message_id);
+          return m->message_id;
+        }
+      }
+    }
+
+    return MessageId();
+  }
+
+  return it->second;
+}
+
+void MessagesManager::force_create_dialog(DialogId dialog_id, const char *source, bool force_update_dialog_pos) {
+  CHECK(dialog_id.is_valid());
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    LOG(INFO) << "Force create " << dialog_id << " from " << source;
+    if (loaded_dialogs_.count(dialog_id) > 0) {
+      return;
+    }
+
+    d = add_dialog(dialog_id);
+    update_dialog_pos(d, false, "force_create_dialog");
+
+    if (have_input_peer(dialog_id, AccessRights::Read)) {
+      if (dialog_id.get_type() != DialogType::SecretChat && !d->notification_settings.is_synchronized) {
+        // asynchronously preload information about the dialog
+        send_get_dialog_query(dialog_id, Auto());
+      }
+    } else {
+      if (!have_dialog_info(dialog_id)) {
+        LOG(ERROR) << "Have no info about " << dialog_id << " received from " << source << ", but forced to create it";
+      } else {
+        LOG_IF(ERROR, Slice(source) != Slice("message forward info") &&
+                          Slice(source) != Slice("on_new_callback_query") &&
+                          Slice(source) != Slice("search public dialog") &&
+                          Slice(source) != Slice("create new secret chat") && !force_update_dialog_pos)
+            << "Have no access to " << dialog_id << " received from " << source << ", but forced to create it";
+      }
+    }
+  } else if (force_update_dialog_pos) {
+    update_dialog_pos(d, false, "force update dialog pos");
+  }
+}
+
+MessagesManager::Dialog *MessagesManager::add_dialog(DialogId dialog_id) {
+  LOG(DEBUG) << "Creating " << dialog_id;
+  CHECK(!have_dialog(dialog_id));
+
+  if (G()->parameters().use_message_db) {
+    // TODO preload dialog asynchronously, remove loading from this function
+    LOG(INFO) << "Synchronously load " << dialog_id << " from database";
+    auto r_value = G()->td_db()->get_dialog_db_sync()->get_dialog(dialog_id);
+    if (r_value.is_ok()) {
+      return add_new_dialog(parse_dialog(dialog_id, r_value.ok()), true);
+    }
+  }
+
+  auto d = make_unique<Dialog>();
+  std::fill(d->message_count_by_index.begin(), d->message_count_by_index.end(), -1);
+  d->dialog_id = dialog_id;
+
+  return add_new_dialog(std::move(d), false);
+}
+
+MessagesManager::Dialog *MessagesManager::add_new_dialog(unique_ptr<Dialog> &&d, bool is_loaded_from_database) {
+  auto dialog_id = d->dialog_id;
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+      break;
+    case DialogType::Channel: {
+      auto channel_type = td_->contacts_manager_->get_channel_type(dialog_id.get_channel_id());
+      if (channel_type == ChannelType::Broadcast) {
+        d->last_read_outbox_message_id = MessageId::max();
+        d->is_last_read_outbox_message_id_inited = true;
+      }
+      if (!d->notification_settings.is_synchronized && channel_type == ChannelType::Megagroup) {
+        d->notification_settings.mute_until = std::numeric_limits<int32>::max();
+      }
+
+      auto pts = load_channel_pts(dialog_id);
+      if (pts > 0) {
+        d->pts = pts;
+        if (is_debug_message_op_enabled()) {
+          d->debug_message_op.emplace_back(Dialog::MessageOp::SetPts, MessageId(), pts, false, false, false,
+                                           "add_new_dialog");
+        }
+      }
+      break;
+    }
+    case DialogType::SecretChat:
+      if (!d->last_new_message_id.is_valid()) {
+        LOG(INFO) << "Set " << d->dialog_id << " last new message id in add_new_dialog";
+        // TODO use date << MessageId::SERVER_ID_SHIFT;
+        d->last_new_message_id = MessageId::min();
+      }
+      for (auto &first_message_id : d->first_database_message_id_by_index) {
+        first_message_id = MessageId::min();
+      }
+      for (auto &message_count : d->message_count_by_index) {
+        if (message_count == -1) {
+          message_count = 0;
+        }
+      }
+
+      d->have_full_history = true;
+      d->need_restore_reply_markup = false;
+      d->notification_settings.is_synchronized = true;
+      d->know_can_report_spam = true;
+      if (!is_loaded_from_database) {
+        d->can_report_spam =
+            td_->contacts_manager_->default_can_report_spam_in_secret_chat(dialog_id.get_secret_chat_id());
+      }
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+  if (!is_loaded_from_database) {
+    on_dialog_updated(dialog_id, "add_new_dialog");
+  }
+
+  unique_ptr<Message> last_database_message = std::move(d->messages);
+  int64 order = d->order;
+  d->order = DEFAULT_ORDER;
+  int32 last_clear_history_date = d->last_clear_history_date;
+  MessageId last_clear_history_message_id = d->last_clear_history_message_id;
+  d->last_clear_history_date = 0;
+  d->last_clear_history_message_id = MessageId();
+
+  if (!is_loaded_from_database) {
+    CHECK(order == DEFAULT_ORDER);
+    CHECK(last_database_message == nullptr);
+  }
+
+  auto dialog_it = dialogs_.emplace(dialog_id, std::move(d)).first;
+
+  loaded_dialogs_.erase(dialog_id);
+
+  Dialog *dialog = dialog_it->second.get();
+  send_update_chat(dialog);
+
+  fix_new_dialog(dialog, std::move(last_database_message), order, last_clear_history_date,
+                 last_clear_history_message_id);
+
+  return dialog;
+}
+
+void MessagesManager::fix_new_dialog(Dialog *d, unique_ptr<Message> &&last_database_message, int64 order,
+                                     int32 last_clear_history_date, MessageId last_clear_history_message_id) {
+  CHECK(d != nullptr);
+  auto dialog_id = d->dialog_id;
+
+  if (d->notification_settings.mute_until <= G()->unix_time()) {
+    d->notification_settings.mute_until = 0;
+  } else {
+    update_dialog_unmute_timeout(d, -1, d->notification_settings.mute_until);
+  }
+
+  auto pending_it = pending_add_dialog_last_database_message_dependent_dialogs_.find(dialog_id);
+  if (pending_it != pending_add_dialog_last_database_message_dependent_dialogs_.end()) {
+    auto pending_dialogs = std::move(pending_it->second);
+    pending_add_dialog_last_database_message_dependent_dialogs_.erase(pending_it);
+
+    for (auto &pending_dialog_id : pending_dialogs) {
+      auto &counter_message = pending_add_dialog_last_database_message_[pending_dialog_id];
+      CHECK(counter_message.first > 0);
+      counter_message.first--;
+      if (counter_message.first == 0) {
+        add_dialog_last_database_message(get_dialog(pending_dialog_id), std::move(counter_message.second));
+        pending_add_dialog_last_database_message_.erase(pending_dialog_id);
+      }
+    }
+  }
+
+  set_dialog_last_clear_history_date(d, last_clear_history_date, last_clear_history_message_id, "add_new_dialog");
+
+  set_dialog_order(d, order, false);
+
+  if (dialog_id.get_type() != DialogType::SecretChat && d->last_new_message_id.is_valid() &&
+      !d->last_new_message_id.is_server()) {
+    // fix wrong last_new_message_id
+    d->last_new_message_id = MessageId(d->last_new_message_id.get() & ~MessageId::FULL_TYPE_MASK);
+  }
+
+  // add last database message to dialog
+  if (last_database_message != nullptr) {
+    auto message_id = last_database_message->message_id;
+    if (!d->first_database_message_id.is_valid()) {
+      LOG(ERROR) << "Bugfixing wrong first_database_message_id to " << message_id << " in " << dialog_id;
+      set_dialog_first_database_message_id(d, message_id, "add_new_dialog");
+    }
+    set_dialog_last_database_message_id(d, message_id, "add_new_dialog");
+    if ((message_id.is_server() || dialog_id.get_type() == DialogType::SecretChat) &&
+        !d->last_new_message_id.is_valid()) {
+      // is it even possible?
+      LOG(ERROR) << "Bugfixing wrong last_new_message_id to " << message_id << " in " << dialog_id;
+      set_dialog_last_new_message_id(d, message_id, "add_new_dialog");
+    }
+
+    int32 dependent_dialog_count = 0;
+    if (last_database_message->forward_info != nullptr) {
+      auto other_dialog_id = last_database_message->forward_info->dialog_id;
+      if (other_dialog_id.is_valid() && !have_dialog(other_dialog_id)) {
+        LOG(INFO) << "Postpone adding of last message in " << dialog_id << " because of cyclic dependency with "
+                  << other_dialog_id;
+        pending_add_dialog_last_database_message_dependent_dialogs_[other_dialog_id].push_back(dialog_id);
+        dependent_dialog_count++;
+      }
+      other_dialog_id = last_database_message->forward_info->from_dialog_id;
+      if (other_dialog_id.is_valid() && !have_dialog(other_dialog_id)) {
+        LOG(INFO) << "Postpone adding of last message in " << dialog_id << " because of cyclic dependency with "
+                  << other_dialog_id;
+        pending_add_dialog_last_database_message_dependent_dialogs_[other_dialog_id].push_back(dialog_id);
+        dependent_dialog_count++;
+      }
+    }
+
+    if (dependent_dialog_count == 0) {
+      add_dialog_last_database_message(d, std::move(last_database_message));
+    } else {
+      // can't add message immediately, because needs to notify first about adding of dependent dialogs
+      pending_add_dialog_last_database_message_[dialog_id] = {dependent_dialog_count, std::move(last_database_message)};
+    }
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::User:
+      break;
+    case DialogType::Chat:
+      if (d->last_read_inbox_message_id.get() < d->last_read_outbox_message_id.get()) {
+        LOG(INFO) << "Have last read outbox message " << d->last_read_outbox_message_id << " in " << dialog_id
+                  << ", but last read inbox message is " << d->last_read_inbox_message_id;
+        // can't fix last_read_inbox_message_id by last_read_outbox_message_id because last_read_outbox_message_id is
+        // just a message id not less than last read outgoing message and less than first unread outgoing message, so
+        // it may not point to the outgoing message
+        // read_history_inbox(dialog_id, d->last_read_outbox_message_id, d->server_unread_count, "add_new_dialog");
+      }
+      break;
+    case DialogType::Channel:
+      break;
+    case DialogType::SecretChat:
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+  }
+
+  update_dialogs_hints(d);
+
+  bool need_get_history = false;
+  if (d->delete_last_message_date != 0) {
+    if (d->last_message_id.is_valid()) {
+      LOG(ERROR) << "Last " << d->deleted_last_message_id << " in " << dialog_id << " was deleted at "
+                 << d->delete_last_message_date << ", but have last " << d->last_message_id;
+      d->delete_last_message_date = 0;
+      d->deleted_last_message_id = MessageId();
+      d->is_last_message_deleted_locally = false;
+      on_dialog_updated(dialog_id, "update_delete_last_message_date");
+    } else {
+      need_get_history = true;
+    }
+  }
+  if (!d->last_database_message_id.is_valid()) {
+    need_get_history = true;
+  }
+
+  if (need_get_history && !td_->auth_manager_->is_bot() && have_input_peer(dialog_id, AccessRights::Read) &&
+      d->order != DEFAULT_ORDER) {
+    get_history_from_the_end(dialog_id, true, false, Auto());
+  }
+}
+
+void MessagesManager::add_dialog_last_database_message(Dialog *d, unique_ptr<Message> &&last_database_message) {
+  CHECK(d != nullptr);
+  CHECK(last_database_message != nullptr);
+  CHECK(last_database_message->left == nullptr);
+  CHECK(last_database_message->right == nullptr);
+
+  auto message_id = last_database_message->message_id;
+  CHECK(d->last_database_message_id == message_id) << message_id << " " << d->last_database_message_id;
+
+  if (!have_input_peer(d->dialog_id, AccessRights::Read)) {
+    // do not add last message to inaccessible dialog
+    return;
+  }
+
+  bool need_update = false;
+  bool need_update_dialog_pos = false;
+  last_database_message->have_previous = false;
+  last_database_message->have_next = false;
+  last_database_message->from_database = true;
+  Message *m = add_message_to_dialog(d, std::move(last_database_message), false, &need_update, &need_update_dialog_pos,
+                                     "add_dialog_last_database_message");
+  if (m != nullptr) {
+    set_dialog_last_message_id(d, message_id, "add_new_dialog");
+    send_update_chat_last_message(d, "add_new_dialog");
+  }
+
+  if (need_update_dialog_pos) {
+    LOG(ERROR) << "Update pos in " << d->dialog_id;
+    update_dialog_pos(d, false, "add_new_dialog");
+  }
+}
+
+void MessagesManager::update_dialogs_hints(const Dialog *d) {
+  if (!td_->auth_manager_->is_bot() && d->order != DEFAULT_ORDER) {
+    dialogs_hints_.add(-d->dialog_id.get(), get_dialog_title(d->dialog_id) + ' ' + get_dialog_username(d->dialog_id));
+  }
+}
+
+void MessagesManager::update_dialogs_hints_rating(const Dialog *d) {
+  if (td_->auth_manager_->is_bot()) {
+    return;
+  }
+  if (d->order == DEFAULT_ORDER) {
+    dialogs_hints_.remove(-d->dialog_id.get());
+  } else {
+    dialogs_hints_.set_rating(-d->dialog_id.get(), -d->order);
+  }
+}
+
+int64 MessagesManager::get_dialog_order(MessageId message_id, int32 message_date) {
+  return (static_cast<int64>(message_date) << 32) + narrow_cast<int32>(message_id.get() >> MessageId::SERVER_ID_SHIFT);
+}
+
+int64 MessagesManager::get_next_pinned_dialog_order() {
+  if (current_pinned_dialog_order_ == DEFAULT_ORDER) {
+    string res_str = G()->td_db()->get_binlog_pmc()->get("dialog_pinned_current_order");
+    if (res_str.empty()) {
+      current_pinned_dialog_order_ = static_cast<int64>(MIN_PINNED_DIALOG_DATE) << 32;
+    } else {
+      current_pinned_dialog_order_ = to_integer<int64>(res_str);
+    }
+  }
+  CHECK(current_pinned_dialog_order_ != DEFAULT_ORDER);
+
+  current_pinned_dialog_order_++;
+  G()->td_db()->get_binlog_pmc()->set("dialog_pinned_current_order", to_string(current_pinned_dialog_order_));
+  LOG(INFO) << "Assign pinned_order = " << current_pinned_dialog_order_;
+  return current_pinned_dialog_order_;
+}
+
+void MessagesManager::update_dialog_pos(Dialog *d, bool remove_from_dialog_list, const char *source,
+                                        bool need_send_update_chat_order) {
+  CHECK(d != nullptr);
+  LOG(INFO) << "Trying to update " << d->dialog_id << " order from " << source;
+  auto dialog_type = d->dialog_id.get_type();
+
+  switch (dialog_type) {
+    case DialogType::User:
+      break;
+    case DialogType::Chat: {
+      auto chat_id = d->dialog_id.get_chat_id();
+      if (!td_->contacts_manager_->get_chat_is_active(chat_id)) {
+        remove_from_dialog_list = true;
+      }
+      break;
+    }
+    case DialogType::Channel: {
+      auto channel_id = d->dialog_id.get_channel_id();
+      auto status = td_->contacts_manager_->get_channel_status(channel_id);
+      if (!status.is_member()) {
+        remove_from_dialog_list = true;
+      }
+      break;
+    }
+    case DialogType::SecretChat:
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      return;
+  }
+
+  int64 new_order = DEFAULT_ORDER;
+  if (!remove_from_dialog_list) {
+    if (d->pinned_order != DEFAULT_ORDER) {
+      LOG(INFO) << "Pin at " << d->pinned_order << " found";
+      new_order = d->pinned_order;
+    }
+    if (d->last_message_id != MessageId()) {
+      auto m = get_message(d, d->last_message_id);
+      CHECK(m != nullptr);
+      LOG(INFO) << "Last message at " << m->date << " found";
+      int64 last_message_order = get_dialog_order(m->message_id, m->date);
+      if (last_message_order > new_order) {
+        new_order = last_message_order;
+      }
+    } else if (d->delete_last_message_date > 0) {
+      LOG(INFO) << "Deleted last " << d->deleted_last_message_id << " at " << d->delete_last_message_date << " found";
+      int64 delete_order = get_dialog_order(d->deleted_last_message_id, d->delete_last_message_date);
+      if (delete_order > new_order) {
+        new_order = delete_order;
+      }
+    } else if (d->last_clear_history_date > 0) {
+      LOG(INFO) << "Clear history at " << d->last_clear_history_date << " found";
+      int64 clear_order = get_dialog_order(d->last_clear_history_message_id, d->last_clear_history_date);
+      if (clear_order > new_order) {
+        new_order = clear_order;
+      }
+    }
+    if (d->draft_message != nullptr) {
+      LOG(INFO) << "Draft message at " << d->draft_message->date << " found";
+      int64 draft_order = get_dialog_order(MessageId(), d->draft_message->date);
+      if (draft_order > new_order) {
+        new_order = draft_order;
+      }
+    }
+    if (dialog_type == DialogType::Channel) {
+      auto date = td_->contacts_manager_->get_channel_date(d->dialog_id.get_channel_id());
+      LOG(INFO) << "Join of channel at " << date << " found";
+      int64 join_order = get_dialog_order(MessageId(), date);
+      if (join_order > new_order) {
+        new_order = join_order;
+      }
+    }
+    if (dialog_type == DialogType::SecretChat) {
+      auto secret_chat_id = d->dialog_id.get_secret_chat_id();
+      auto date = td_->contacts_manager_->get_secret_chat_date(secret_chat_id);
+      auto state = td_->contacts_manager_->get_secret_chat_state(secret_chat_id);
+      // do not return removed from the chat list closed secret chats
+      if (date != 0 && (d->order != DEFAULT_ORDER || state != SecretChatState::Closed)) {
+        LOG(INFO) << "Creation of secret chat at " << date << " found";
+        int64 creation_order = get_dialog_order(MessageId(), date);
+        if (creation_order > new_order) {
+          new_order = creation_order;
+        }
+      }
+    }
+    if (new_order == DEFAULT_ORDER && !d->is_empty) {
+      // if there is no known messages in the dialog, just leave it where it is
+      LOG(INFO) << "There is no known messages in the dialog";
+      return;
+    }
+  }
+
+  if (set_dialog_order(d, new_order, need_send_update_chat_order)) {
+    on_dialog_updated(d->dialog_id, "update_dialog_pos");
+  }
+}
+
+bool MessagesManager::set_dialog_order(Dialog *d, int64 new_order, bool need_send_update_chat_order) {
+  CHECK(d != nullptr);
+  DialogDate old_date(d->order, d->dialog_id);
+  DialogDate new_date(new_order, d->dialog_id);
+
+  std::set<DialogDate> *ordered_dialogs_set = nullptr;
+  switch (d->dialog_id.get_type()) {
+    case DialogType::User:
+    case DialogType::Chat:
+    case DialogType::Channel:
+    case DialogType::SecretChat:
+      ordered_dialogs_set = &ordered_server_dialogs_;
+      break;
+    case DialogType::None:
+    default:
+      UNREACHABLE();
+      return false;
+  }
+
+  if (old_date == new_date) {
+    if (new_order == DEFAULT_ORDER && ordered_dialogs_set->count(old_date) == 0) {
+      ordered_dialogs_set->insert(new_date);
+    }
+    LOG(INFO) << "Dialog order is not changed: " << new_order;
+    return false;
+  }
+  LOG(INFO) << "Update order of " << d->dialog_id << " from " << d->order << " to " << new_order;
+
+  bool need_update = false;
+  if (old_date <= last_dialog_date_) {
+    if (ordered_dialogs_.erase(old_date) == 0) {
+      UNREACHABLE();
+    }
+    need_update = true;
+  }
+  bool is_new = ordered_dialogs_set->erase(old_date) == 0;
+  LOG_IF(ERROR, is_new && d->order != DEFAULT_ORDER) << d->dialog_id << " not found in the chat list";
+
+  int64 updated_to = 0;
+  if (new_date <= last_dialog_date_) {
+    ordered_dialogs_.insert(new_date);
+    need_update = true;
+    updated_to = new_order;
+  }
+  ordered_dialogs_set->insert(new_date);
+
+  bool add_to_hints = (d->order == DEFAULT_ORDER);
+
+  if (!is_new && (d->order == DEFAULT_ORDER || new_order == DEFAULT_ORDER)) {
+    auto unread_count = d->server_unread_count + d->local_unread_count;
+    if (unread_count != 0 && is_unread_count_inited_) {
+      const char *source = "on_dialog_join";
+      if (d->order != DEFAULT_ORDER) {
+        unread_count = -unread_count;
+        source = "on_dialog_leave";
+      } else {
+        CHECK(new_order != DEFAULT_ORDER);
+      }
+
+      unread_message_total_count_ += unread_count;
+      if (d->notification_settings.mute_until != 0) {
+        unread_message_muted_count_ += unread_count;
+      }
+      send_update_unread_message_count(d->dialog_id, true, source);
+    }
+  }
+
+  d->order = new_order;
+
+  if (add_to_hints) {
+    update_dialogs_hints(d);
+  }
+  update_dialogs_hints_rating(d);
+
+  if (need_update && need_send_update_chat_order) {
+    send_closure(G()->td(), &Td::send_update, make_tl_object<td_api::updateChatOrder>(d->dialog_id.get(), updated_to));
+  }
+  return true;
+}
+
+void MessagesManager::update_last_dialog_date() {
+  auto old_last_dialog_date = last_dialog_date_;
+  last_dialog_date_ = last_server_dialog_date_;  // std::min
+  CHECK(old_last_dialog_date <= last_dialog_date_);
+
+  LOG(INFO) << "Update last dialog date from " << old_last_dialog_date << " to " << last_dialog_date_;
+  LOG(INFO) << "Know about " << ordered_server_dialogs_.size() << " chats";
+
+  if (old_last_dialog_date != last_dialog_date_) {
+    for (auto it = ordered_server_dialogs_.upper_bound(old_last_dialog_date);
+         it != ordered_server_dialogs_.end() && *it <= last_dialog_date_; ++it) {
+      auto dialog_id = it->get_dialog_id();
+      auto d = get_dialog(dialog_id);
+      CHECK(d != nullptr);
+      ordered_dialogs_.insert(DialogDate(d->order, d->dialog_id));
+      send_closure(G()->td(), &Td::send_update, make_tl_object<td_api::updateChatOrder>(d->dialog_id.get(), d->order));
+    }
+
+    if (last_dialog_date_ == MAX_DIALOG_DATE) {
+      recalc_unread_message_count();
+    }
+  }
+
+  if (G()->parameters().use_message_db && last_database_server_dialog_date_ < last_server_dialog_date_) {
+    auto last_server_dialog_date_string = to_string(last_server_dialog_date_.get_order()) + " " +
+                                          to_string(last_server_dialog_date_.get_dialog_id().get());
+    G()->td_db()->get_binlog_pmc()->set("last_server_dialog_date", last_server_dialog_date_string);
+    LOG(INFO) << "Save last server dialog date " << last_server_dialog_date_string;
+    last_database_server_dialog_date_ = last_server_dialog_date_;
+    last_loaded_database_dialog_date_ = last_server_dialog_date_;
+  }
+}
+
+uint64 MessagesManager::get_sequence_dispatcher_id(DialogId dialog_id, int32 message_content_type) {
+  switch (message_content_type) {
+    case MessageAnimation::ID:
+    case MessageAudio::ID:
+    case MessageDocument::ID:
+    case MessagePhoto::ID:
+    case MessageSticker::ID:
+    case MessageVideo::ID:
+    case MessageVideoNote::ID:
+    case MessageVoiceNote::ID:
+      return static_cast<uint64>(dialog_id.get() * 2 + 1);
+    default:
+      return static_cast<uint64>(dialog_id.get() * 2 + 2);
+  }
+}
+
+MessagesManager::Dialog *MessagesManager::get_dialog(DialogId dialog_id) {
+  auto it = dialogs_.find(dialog_id);
+  return it == dialogs_.end() ? nullptr : it->second.get();
+}
+
+const MessagesManager::Dialog *MessagesManager::get_dialog(DialogId dialog_id) const {
+  auto it = dialogs_.find(dialog_id);
+  return it == dialogs_.end() ? nullptr : it->second.get();
+}
+
+bool MessagesManager::have_dialog_force(DialogId dialog_id) {
+  return loaded_dialogs_.count(dialog_id) > 0 || get_dialog_force(dialog_id) != nullptr;
+}
+
+MessagesManager::Dialog *MessagesManager::get_dialog_force(DialogId dialog_id) {
+  // TODO remove most usages of that function, preload dialog asynchronously if possible
+  auto it = dialogs_.find(dialog_id);
+  if (it != dialogs_.end()) {
+    return it->second.get();
+  }
+
+  if (!dialog_id.is_valid() || !G()->parameters().use_message_db || loaded_dialogs_.count(dialog_id) > 0) {
+    return nullptr;
+  }
+
+  LOG(INFO) << "Try to load " << dialog_id << " from database";
+  auto d = on_load_dialog_from_database(G()->td_db()->get_dialog_db_sync()->get_dialog(dialog_id));
+  CHECK(d == nullptr || d->dialog_id == dialog_id);
+  return d;
+}
+
+unique_ptr<MessagesManager::Dialog> MessagesManager::parse_dialog(DialogId dialog_id, const BufferSlice &value) {
+  LOG(INFO) << "Loaded " << dialog_id << " from database";
+  auto d = make_unique<Dialog>();
+  std::fill(d->message_count_by_index.begin(), d->message_count_by_index.end(), -1);
+
+  loaded_dialogs_.insert(dialog_id);
+
+  log_event_parse(*d, value.as_slice()).ensure();
+  CHECK(dialog_id == d->dialog_id);
+
+  Dependencies dependencies;
+  add_dialog_dependencies(dependencies, dialog_id);
+  if (d->messages != nullptr) {
+    add_message_dependencies(dependencies, dialog_id, d->messages.get());
+  }
+  resolve_dependencies_force(dependencies);
+
+  return d;
+}
+
+MessagesManager::Dialog *MessagesManager::on_load_dialog_from_database(const Result<BufferSlice> &r_value) {
+  CHECK(G()->parameters().use_message_db);
+
+  if (!r_value.is_ok()) {
+    return nullptr;
+  }
+
+  // hack
+  LogEventParser dialog_id_parser(r_value.ok().as_slice());
+  int32 flags;
+  DialogId dialog_id;
+  parse(flags, dialog_id_parser);
+  parse(dialog_id, dialog_id_parser);
+
+  auto old_d = get_dialog(dialog_id);
+  if (old_d != nullptr) {
+    return old_d;
+  }
+
+  return add_new_dialog(parse_dialog(dialog_id, r_value.ok()), true);
+}
+
+void MessagesManager::load_notification_settings() {
+  if (td_->auth_manager_->is_bot()) {
+    return;
+  }
+  if (!users_notification_settings_.is_synchronized) {
+    td_->create_handler<GetNotifySettingsQuery>(Promise<>())->send(NOTIFICATION_SETTINGS_FOR_PRIVATE_CHATS);
+  }
+  if (!chats_notification_settings_.is_synchronized) {
+    td_->create_handler<GetNotifySettingsQuery>(Promise<>())->send(NOTIFICATION_SETTINGS_FOR_GROUP_CHATS);
+  }
+  if (!dialogs_notification_settings_.is_synchronized) {
+    td_->create_handler<GetNotifySettingsQuery>(Promise<>())->send(NOTIFICATION_SETTINGS_FOR_ALL_CHATS);
+  }
+}
+
+string MessagesManager::get_channel_pts_key(DialogId dialog_id) {
+  CHECK(dialog_id.get_type() == DialogType::Channel);
+  auto channel_id = dialog_id.get_channel_id();
+  return "ch.p" + to_string(channel_id.get());
+}
+
+int32 MessagesManager::load_channel_pts(DialogId dialog_id) const {
+  auto pts = to_integer<int32>(G()->td_db()->get_binlog_pmc()->get(get_channel_pts_key(dialog_id)));
+  LOG(INFO) << "Load " << dialog_id << " pts = " << pts;
+  return pts;
+}
+
+void MessagesManager::set_channel_pts(Dialog *d, int32 new_pts, const char *source) const {
+  CHECK(d != nullptr);
+  CHECK(d->dialog_id.get_type() == DialogType::Channel);
+
+  LOG_IF(ERROR, running_get_channel_difference(d->dialog_id))
+      << "Set pts of " << d->dialog_id << " to " << new_pts << " while running getChannelDifference";
+
+  if (is_debug_message_op_enabled()) {
+    d->debug_message_op.emplace_back(Dialog::MessageOp::SetPts, MessageId(), new_pts, false, false, false, source);
+  }
+
+  // TODO delete_first_messages support in channels
+  if (new_pts == std::numeric_limits<int32>::max()) {
+    LOG(ERROR) << "Update " << d->dialog_id << " pts to -1";
+    G()->td_db()->get_binlog_pmc()->erase(get_channel_pts_key(d->dialog_id));
+    d->pts = std::numeric_limits<int32>::max();
+    return;
+  }
+  if (new_pts > d->pts || (0 < new_pts && new_pts < d->pts - 99999)) {  // pts can only go up or drop cardinally
+    if (new_pts < d->pts - 99999) {
+      LOG(WARNING) << "Pts of " << d->dialog_id << " decreases from " << d->pts << " to " << new_pts;
+    } else {
+      LOG(INFO) << "Update " << d->dialog_id << " pts to " << new_pts;
+    }
+
+    d->pts = new_pts;
+    G()->td_db()->get_binlog_pmc()->set(get_channel_pts_key(d->dialog_id), to_string(new_pts));
+  } else if (new_pts < d->pts) {
+    LOG(ERROR) << "Receive wrong pts " << new_pts << " in " << d->dialog_id << " . Current pts is " << d->pts;
+  }
+}
+
+bool MessagesManager::running_get_channel_difference(DialogId dialog_id) const {
+  return active_get_channel_differencies_.count(dialog_id) > 0;
+}
+
+class MessagesManager::GetChannelDifferenceLogEvent {
+ public:
+  ChannelId channel_id;
+  int64 access_hash;
+
+  GetChannelDifferenceLogEvent() : channel_id(), access_hash() {
+  }
+
+  GetChannelDifferenceLogEvent(ChannelId channel_id, int64 access_hash)
+      : channel_id(channel_id), access_hash(access_hash) {
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(channel_id, storer);
+    td::store(access_hash, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(channel_id, parser);
+    td::parse(access_hash, parser);
+  }
+};
+
+void MessagesManager::get_channel_difference(DialogId dialog_id, int32 pts, bool force, const char *source) {
+  if (channel_get_difference_retry_timeout_.has_timeout(dialog_id.get())) {
+    LOG(INFO) << "Skip running channels.getDifference for " << dialog_id << " from " << source
+              << " because it is scheduled for later time";
+    return;
+  }
+
+  auto input_channel = td_->contacts_manager_->get_input_channel(dialog_id.get_channel_id());
+  if (input_channel == nullptr) {
+    LOG(ERROR) << "Skip running channels.getDifference for " << dialog_id << " from " << source
+               << " because have no info about the chat";
+    after_get_channel_difference(dialog_id, false);
+    return;
+  }
+
+  if (force && get_channel_difference_to_logevent_id_.count(dialog_id) == 0) {
+    auto channel_id = dialog_id.get_channel_id();
+    CHECK(input_channel->get_id() == telegram_api::inputChannel::ID);
+    auto access_hash = static_cast<const telegram_api::inputChannel &>(*input_channel).access_hash_;
+    auto logevent = GetChannelDifferenceLogEvent(channel_id, access_hash);
+    auto storer = LogEventStorerImpl<GetChannelDifferenceLogEvent>(logevent);
+    auto logevent_id =
+        BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::GetChannelDifference, storer);
+
+    get_channel_difference_to_logevent_id_.emplace(dialog_id, logevent_id);
+  }
+
+  return do_get_channel_difference(dialog_id, pts, force, std::move(input_channel), source);
+}
+
+void MessagesManager::do_get_channel_difference(DialogId dialog_id, int32 pts, bool force,
+                                                tl_object_ptr<telegram_api::InputChannel> &&input_channel,
+                                                const char *source) {
+  auto inserted = active_get_channel_differencies_.emplace(dialog_id, source);
+  if (!inserted.second) {
+    LOG(INFO) << "Skip running channels.getDifference for " << dialog_id << " from " << source
+              << " because it has already been run";
+    return;
+  }
+
+  int32 limit = td_->auth_manager_->is_bot() ? MAX_BOT_CHANNEL_DIFFERENCE : MAX_CHANNEL_DIFFERENCE;
+  if (pts <= 0) {
+    pts = 1;
+    limit = MIN_CHANNEL_DIFFERENCE;
+  }
+
+  LOG(INFO) << "-----BEGIN GET CHANNEL DIFFERENCE----- for " << dialog_id << " with pts " << pts << " and limit "
+            << limit << " from " << source;
+
+  td_->create_handler<GetChannelDifferenceQuery>()->send(dialog_id, std::move(input_channel), pts, limit, force);
+}
+
+void MessagesManager::process_get_channel_difference_updates(
+    DialogId dialog_id, vector<tl_object_ptr<telegram_api::Message>> &&new_messages,
+    vector<tl_object_ptr<telegram_api::Update>> &&other_updates) {
+  LOG(INFO) << "In get channel difference for " << dialog_id << " receive " << new_messages.size() << " messages and "
+            << other_updates.size() << " other updates";
+  for (auto &update : other_updates) {
+    if (update->get_id() == telegram_api::updateMessageID::ID) {
+      auto sent_message_update = move_tl_object_as<telegram_api::updateMessageID>(update);
+      on_update_message_id(sent_message_update->random_id_, MessageId(ServerMessageId(sent_message_update->id_)),
+                           "get_channel_difference");
+      update = nullptr;
+    }
+  }
+
+  for (auto &message : new_messages) {
+    on_get_message(std::move(message), true, true, true, true, "get channel difference");
+  }
+
+  for (auto &update : other_updates) {
+    if (update != nullptr) {
+      switch (update->get_id()) {
+        case telegram_api::updateDeleteChannelMessages::ID:
+          process_channel_update(std::move(update));
+          break;
+        case telegram_api::updateEditChannelMessage::ID:
+          process_channel_update(std::move(update));
+          break;
+        default:
+          LOG(ERROR) << "Unsupported update received in getChannelDifference: " << oneline(to_string(update));
+          break;
+      }
+    }
+  }
+  CHECK(!running_get_channel_difference(dialog_id)) << '"' << active_get_channel_differencies_[dialog_id] << '"';
+}
+
+void MessagesManager::on_get_channel_dialog(DialogId dialog_id, MessageId last_message_id,
+                                            MessageId read_inbox_max_message_id, int32 server_unread_count,
+                                            int32 unread_mention_count, MessageId read_outbox_max_message_id,
+                                            vector<tl_object_ptr<telegram_api::Message>> &&messages) {
+  std::unordered_map<FullMessageId, tl_object_ptr<telegram_api::Message>, FullMessageIdHash> full_message_id_to_message;
+  for (auto &message : messages) {
+    auto message_id = get_message_id(message);
+    auto message_dialog_id = get_message_dialog_id(message);
+    if (!message_dialog_id.is_valid()) {
+      message_dialog_id = dialog_id;
+    }
+    auto full_message_id = FullMessageId(message_dialog_id, message_id);
+    full_message_id_to_message[full_message_id] = std::move(message);
+  }
+
+  FullMessageId last_full_message_id(dialog_id, last_message_id);
+  if (last_message_id.is_valid()) {
+    if (full_message_id_to_message.count(last_full_message_id) == 0) {
+      LOG(ERROR) << "Last " << last_message_id << " in " << dialog_id << " not found. Have:";
+      for (auto &message : full_message_id_to_message) {
+        LOG(ERROR) << to_string(message.second);
+      }
+      return;
+    }
+  } else {
+    LOG(ERROR) << "Receive as last " << last_message_id;
+    return;
+  }
+
+  Dialog *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+
+  // TODO gaps support
+  // There are many ways of handling a gap in a channel:
+  // 1) Delete all known messages in the chat, begin from scratch. It is easy to implement, but suddenly disappearing
+  //    messages looks awful for the user.
+  // 2) Save all messages loaded in the memory until application restart, but delete all messages from database.
+  //    Messages left in the memory must be lazily updated using calls to getHistory. It looks much smoothly for the
+  //    user, he will need to redownload messages only after client restart. Unsynchronized messages left in the
+  //    memory shouldn't be saved to database, results of getHistory and getMessage must be used to update state of
+  //    deleted and edited messages left in the memory.
+  // 3) Save all messages loaded in the memory and stored in the database without saving that some messages form
+  //    continuous ranges. Messages in the database will be excluded from results of getChatHistory and
+  //    searchChatMessages after application restart and will be available only through getMessage.
+  //    Every message should still be checked using getHistory. It has more disadvantages over 2) than advantages.
+  // 4) Save all messages with saving all data about continuous message ranges. Messages from the database may be used
+  //    as results of getChatHistory and (if implemented continuous ranges support for searching shared media)
+  //    searchChatMessages. The messages should still be lazily checked using getHistory, but they are still available
+  //    offline. It is the best way for gaps support, but it is pretty hard to implement correctly.
+  // It should be also noted that some messages like live location messages shouldn't be deleted.
+  // delete_all_dialog_messages_from_database(dialog_id, d->last_database_message_id, "on_get_channel_dialog");
+
+  set_dialog_first_database_message_id(d, MessageId(), "on_get_channel_dialog");
+  set_dialog_last_database_message_id(d, MessageId(), "on_get_channel_dialog");
+  d->have_full_history = false;
+  for (auto &first_message_id : d->first_database_message_id_by_index) {
+    first_message_id = MessageId();
+  }
+  std::fill(d->message_count_by_index.begin(), d->message_count_by_index.end(), -1);
+
+  on_dialog_updated(dialog_id, "on_get_channel_dialog 10");
+
+  // TODO support last_message_id.get() < d->last_new_message_id.get()
+  if (last_message_id.get() > d->last_new_message_id.get()) {  // if last message is really a new message
+    d->last_new_message_id = MessageId();
+    set_dialog_last_message_id(d, MessageId(), "on_get_channel_dialog 20");
+    send_update_chat_last_message(d, "on_get_channel_dialog 30");
+    auto added_full_message_id = on_get_message(std::move(full_message_id_to_message[last_full_message_id]), true, true,
+                                                true, true, "channel difference too long");
+    if (added_full_message_id.get_message_id().is_valid()) {
+      if (added_full_message_id.get_message_id() == d->last_new_message_id) {
+        CHECK(last_full_message_id == added_full_message_id);
+        CHECK(d->last_message_id == d->last_new_message_id);
+      } else {
+        LOG(ERROR) << added_full_message_id << " doesn't became last new message";
+        dump_debug_message_op(d, 2);
+      }
+    } else {
+      set_dialog_last_new_message_id(d, last_full_message_id.get_message_id(),
+                                     "on_get_channel_dialog 40");  // skip updates about some messages
+    }
+  }
+
+  if (d->server_unread_count != server_unread_count || d->last_read_inbox_message_id != read_inbox_max_message_id) {
+    set_dialog_last_read_inbox_message_id(d, read_inbox_max_message_id, server_unread_count, d->local_unread_count,
+                                          false, "on_get_channel_dialog 50");
+  }
+  if (d->unread_mention_count != unread_mention_count) {
+    d->unread_mention_count = unread_mention_count;
+    d->message_count_by_index[search_messages_filter_index(SearchMessagesFilter::UnreadMention)] =
+        d->unread_mention_count;
+    send_update_chat_unread_mention_count(d);
+  }
+
+  if (d->last_read_outbox_message_id != read_outbox_max_message_id) {
+    set_dialog_last_read_outbox_message_id(d, read_outbox_max_message_id);
+  }
+}
+
+void MessagesManager::on_get_channel_difference(
+    DialogId dialog_id, int32 request_pts, int32 request_limit,
+    tl_object_ptr<telegram_api::updates_ChannelDifference> &&difference_ptr) {
+  LOG(INFO) << "----- END  GET CHANNEL DIFFERENCE----- for " << dialog_id;
+  CHECK(active_get_channel_differencies_.count(dialog_id) == 1);
+  active_get_channel_differencies_.erase(dialog_id);
+  auto d = get_dialog_force(dialog_id);
+
+  if (difference_ptr == nullptr) {
+    bool have_access = have_input_peer(dialog_id, AccessRights::Read);
+    if (have_access) {
+      CHECK(d != nullptr);
+      channel_get_difference_retry_timeout_.add_timeout_in(dialog_id.get(), d->retry_get_difference_timeout);
+      d->retry_get_difference_timeout *= 2;
+      if (d->retry_get_difference_timeout > 60) {
+        d->retry_get_difference_timeout = Random::fast(60, 80);
+      }
+    } else {
+      after_get_channel_difference(dialog_id, false);
+    }
+    return;
+  }
+
+  bool need_update_dialog_pos = false;
+  if (d == nullptr) {
+    d = add_dialog(dialog_id);
+    need_update_dialog_pos = true;
+  }
+
+  int32 cur_pts = d->pts <= 0 ? 1 : d->pts;
+  LOG_IF(ERROR, cur_pts != request_pts) << "Channel pts has changed from " << request_pts << " to " << d->pts << " in "
+                                        << dialog_id << " during getChannelDifference";
+
+  LOG(INFO) << "Receive result of getChannelDifference for " << dialog_id << " with pts = " << request_pts
+            << " and limit = " << request_limit << ": " << to_string(difference_ptr);
+
+  d->retry_get_difference_timeout = 1;
+
+  bool is_final = true;
+  int32 timeout = 0;
+  switch (difference_ptr->get_id()) {
+    case telegram_api::updates_channelDifferenceEmpty::ID: {
+      auto difference = move_tl_object_as<telegram_api::updates_channelDifferenceEmpty>(difference_ptr);
+      int32 flags = difference->flags_;
+      is_final = (flags & CHANNEL_DIFFERENCE_FLAG_IS_FINAL) != 0;
+      LOG_IF(ERROR, !is_final) << "Receive channelDifferenceEmpty as result of getChannelDifference with pts = "
+                               << request_pts << " and limit = " << request_limit << " in " << dialog_id
+                               << ", but it is not final";
+      if (flags & CHANNEL_DIFFERENCE_FLAG_HAS_TIMEOUT) {
+        timeout = difference->timeout_;
+      }
+
+      // bots can receive channelDifferenceEmpty with pts bigger than known pts
+      LOG_IF(ERROR, request_pts != difference->pts_ && !td_->auth_manager_->is_bot())
+          << "Receive channelDifferenceEmpty as result of getChannelDifference with pts = " << request_pts
+          << " and limit = " << request_limit << " in " << dialog_id << ", but pts has changed from " << request_pts
+          << " to " << difference->pts_;
+      set_channel_pts(d, difference->pts_, "channel difference empty");
+      break;
+    }
+    case telegram_api::updates_channelDifference::ID: {
+      auto difference = move_tl_object_as<telegram_api::updates_channelDifference>(difference_ptr);
+
+      int32 flags = difference->flags_;
+      is_final = (flags & CHANNEL_DIFFERENCE_FLAG_IS_FINAL) != 0;
+      if (flags & CHANNEL_DIFFERENCE_FLAG_HAS_TIMEOUT) {
+        timeout = difference->timeout_;
+      }
+
+      auto new_pts = difference->pts_;
+      if (request_pts >= new_pts) {
+        LOG(ERROR) << "Receive channelDifference as result of getChannelDifference with pts = " << request_pts
+                   << " and limit = " << request_limit << " in " << dialog_id << ", but pts has changed from " << d->pts
+                   << " to " << new_pts << ". Difference: " << oneline(to_string(difference));
+        new_pts = request_pts + 1;
+      }
+
+      td_->contacts_manager_->on_get_users(std::move(difference->users_));
+      td_->contacts_manager_->on_get_chats(std::move(difference->chats_));
+
+      process_get_channel_difference_updates(dialog_id, std::move(difference->new_messages_),
+                                             std::move(difference->other_updates_));
+
+      set_channel_pts(d, new_pts, "channel difference");
+      break;
+    }
+    case telegram_api::updates_channelDifferenceTooLong::ID: {
+      auto difference = move_tl_object_as<telegram_api::updates_channelDifferenceTooLong>(difference_ptr);
+
+      int32 flags = difference->flags_;
+      is_final = (flags & CHANNEL_DIFFERENCE_FLAG_IS_FINAL) != 0;
+      if (flags & CHANNEL_DIFFERENCE_FLAG_HAS_TIMEOUT) {
+        timeout = difference->timeout_;
+      }
+
+      auto new_pts = difference->pts_;
+      if (request_pts + request_limit > new_pts) {
+        LOG(ERROR) << "Receive channelDifferenceTooLong as result of getChannelDifference with pts = " << request_pts
+                   << " and limit = " << request_limit << " in " << dialog_id << ", but pts has changed from " << d->pts
+                   << " to " << new_pts << ". Difference: " << oneline(to_string(difference));
+        if (request_pts >= new_pts) {
+          new_pts = request_pts + 1;
+        }
+      }
+
+      td_->contacts_manager_->on_get_users(std::move(difference->users_));
+      td_->contacts_manager_->on_get_chats(std::move(difference->chats_));
+
+      on_get_channel_dialog(dialog_id, MessageId(ServerMessageId(difference->top_message_)),
+                            MessageId(ServerMessageId(difference->read_inbox_max_id_)), difference->unread_count_,
+                            difference->unread_mentions_count_,
+                            MessageId(ServerMessageId(difference->read_outbox_max_id_)),
+                            std::move(difference->messages_));
+      need_update_dialog_pos = true;
+
+      set_channel_pts(d, new_pts, "channel difference too long");
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+
+  if (need_update_dialog_pos) {
+    update_dialog_pos(d, false, "on_get_channel_difference");
+  }
+
+  if (!is_final) {
+    LOG_IF(ERROR, timeout > 0) << "Have timeout in not final ChannelDifference in " << dialog_id;
+    get_channel_difference(dialog_id, d->pts, true, "on_get_channel_difference");
+    return;
+  }
+
+  LOG_IF(ERROR, timeout == 0) << "Have no timeout in final ChannelDifference in " << dialog_id;
+  if (timeout > 0 && d->is_opened) {
+    channel_get_difference_timeout_.add_timeout_in(dialog_id.get(), timeout);
+  }
+  after_get_channel_difference(dialog_id, true);
+}
+
+void MessagesManager::after_get_channel_difference(DialogId dialog_id, bool success) {
+  CHECK(!running_get_channel_difference(dialog_id)) << '"' << active_get_channel_differencies_[dialog_id] << '"';
+
+  auto logevent_it = get_channel_difference_to_logevent_id_.find(dialog_id);
+  if (logevent_it != get_channel_difference_to_logevent_id_.end()) {
+    BinlogHelper::erase(G()->td_db()->get_binlog(), logevent_it->second);
+    get_channel_difference_to_logevent_id_.erase(logevent_it);
+  }
+
+  auto d = get_dialog(dialog_id);
+  bool have_access = have_input_peer(dialog_id, AccessRights::Read);
+  if (!have_access) {
+    if (d != nullptr) {
+      d->postponed_channel_updates.clear();
+    }
+  } else if (d->postponed_channel_updates.size()) {
+    LOG(INFO) << "Begin to apply postponed channel updates";
+    while (!d->postponed_channel_updates.empty()) {
+      auto it = d->postponed_channel_updates.begin();
+      auto update = std::move(it->second.update);
+      auto update_pts = it->second.pts;
+      auto update_pts_count = it->second.pts_count;
+      d->postponed_channel_updates.erase(it);
+      auto old_size = d->postponed_channel_updates.size();
+      auto update_id = update->get_id();
+      add_pending_channel_update(dialog_id, std::move(update), update_pts, update_pts_count,
+                                 "apply postponed channel updates", true);
+      if (d->postponed_channel_updates.size() != old_size || running_get_channel_difference(dialog_id)) {
+        if (success && update_pts < d->pts + 10000 && update_pts_count == 1) {
+          // if getChannelDifference was successful and update pts is near channel pts,
+          // we hope that the update eventually can be applied
+          LOG(INFO) << "Can't apply postponed channel updates";
+        } else {
+          // otherwise we protecting from getChannelDifference repeating calls by dropping pending updates
+          LOG(ERROR) << "Failed to apply postponed updates of type " << update_id << " in " << dialog_id << " with pts "
+                     << d->pts << ", update pts is " << update_pts << ", update pts count is " << update_pts_count;
+          d->postponed_channel_updates.clear();
+        }
+        break;
+      }
+    }
+    LOG(INFO) << "Finish to apply postponed channel updates";
+  }
+
+  if (postponed_chat_read_inbox_updates_.erase(dialog_id) > 0) {
+    send_update_chat_read_inbox(d, true, "after_get_channel_difference");
+  }
+
+  auto it_get_message_requests = postponed_get_message_requests_.find(dialog_id);
+  if (it_get_message_requests != postponed_get_message_requests_.end()) {
+    CHECK(d != nullptr);
+    for (auto &request : it_get_message_requests->second) {
+      auto message_id = request.first;
+      LOG(INFO) << "Run postponed getMessage request for " << message_id << " in " << dialog_id;
+      if (d->last_new_message_id != MessageId() && message_id.get() > d->last_new_message_id.get()) {
+        // message will not be added to the dialog anyway, get channel difference didn't help
+        request.second.set_value(Unit());
+      } else {
+        get_messages_from_server({FullMessageId{dialog_id, message_id}}, std::move(request.second));
+      }
+    }
+    postponed_get_message_requests_.erase(it_get_message_requests);
+  }
+
+  auto it = pending_channel_on_get_dialogs_.find(dialog_id);
+  if (it != pending_channel_on_get_dialogs_.end()) {
+    LOG(INFO) << "Apply postponed results of channel getDialogs for " << dialog_id;
+    PendingOnGetDialogs res = std::move(it->second);
+    pending_channel_on_get_dialogs_.erase(it);
+
+    on_get_dialogs(std::move(res.dialogs), res.total_count, std::move(res.messages), std::move(res.promise));
+  }
+
+  // TODO resend some messages
+}
+
+void MessagesManager::update_used_hashtags(DialogId dialog_id, const Message *m) {
+  CHECK(m != nullptr);
+  if (m->via_bot_user_id.is_valid() || m->content->get_id() != MessageText::ID) {
+    return;
+  }
+  auto message_text = static_cast<const MessageText *>(m->content.get());
+  const unsigned char *ptr = Slice(message_text->text.text).ubegin();
+  const unsigned char *end = Slice(message_text->text.text).uend();
+  int32 utf16_pos = 0;
+  for (auto &entity : message_text->text.entities) {
+    if (entity.type != MessageEntity::Type::Hashtag) {
+      continue;
+    }
+    while (utf16_pos < entity.offset && ptr < end) {
+      utf16_pos += 1 + (ptr[0] >= 0xf0);
+      ptr = next_utf8_unsafe(ptr, nullptr);
+    }
+    CHECK(utf16_pos == entity.offset);
+    auto from = ptr;
+
+    while (utf16_pos < entity.offset + entity.length && ptr < end) {
+      utf16_pos += 1 + (ptr[0] >= 0xf0);
+      ptr = next_utf8_unsafe(ptr, nullptr);
+    }
+    CHECK(utf16_pos == entity.offset + entity.length);
+    auto to = ptr;
+
+    send_closure(td_->hashtag_hints_, &HashtagHints::hashtag_used, Slice(from + 1, to).str());
+  }
+}
+
+MessagesManager::Message *MessagesManager::continue_send_message(DialogId dialog_id, unique_ptr<Message> &&m,
+                                                                 uint64 logevent_id) {
+  Dialog *d = get_dialog_force(dialog_id);
+  if (d == nullptr) {
+    LOG(ERROR) << "Can't find " << dialog_id << " to resend a message";
+    BinlogHelper::erase(G()->td_db()->get_binlog(), logevent_id);
+    return nullptr;
+  }
+
+  m->message_id = get_next_yet_unsent_message_id(d);
+  m->random_y = get_random_y(m->message_id);
+  m->date = G()->unix_time();
+  m->have_previous = true;
+  m->have_next = true;
+
+  LOG(INFO) << "Continue to send " << m->message_id << " to " << dialog_id << " from binlog";
+
+  if (!have_input_peer(dialog_id, AccessRights::Read)) {
+    BinlogHelper::erase(G()->td_db()->get_binlog(), logevent_id);
+    return nullptr;
+  }
+
+  message_random_ids_.insert(m->random_id);
+
+  bool need_update = false;
+  bool need_update_dialog_pos = false;
+  auto result_message =
+      add_message_to_dialog(d, std::move(m), false, &need_update, &need_update_dialog_pos, "resend message");
+  CHECK(result_message != nullptr);
+  // CHECK(need_update_dialog_pos == true);
+
+  auto can_send_status = can_send_message(dialog_id);
+  if (can_send_status.is_error()) {
+    LOG(INFO) << "Can't resend a message to " << dialog_id << ": " << can_send_status.error();
+
+    int64 random_id = begin_send_message(dialog_id, result_message);
+    on_send_message_fail(random_id, can_send_status.move_as_error());
+    return nullptr;
+  }
+
+  send_update_new_message(d, result_message);
+  if (need_update_dialog_pos) {
+    send_update_chat_last_message(d, "on_resend_message");
+  }
+  return result_message;
+}
+
+void MessagesManager::on_binlog_events(vector<BinlogEvent> &&events) {
+  for (auto &event : events) {
+    switch (event.type_) {
+      case LogEvent::HandlerType::SendMessage: {
+        if (!G()->parameters().use_message_db) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        SendMessageLogEvent log_event;
+        log_event_parse(log_event, event.data_).ensure();
+
+        auto dialog_id = log_event.dialog_id;
+        auto m = std::move(log_event.m_out);
+        m->send_message_logevent_id = event.id_;
+
+        if (m->content->get_id() == MessageUnsupported::ID) {
+          LOG(ERROR) << "Message content is invalid: " << format::as_hex_dump<4>(Slice(event.data_));
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          continue;
+        }
+
+        Dependencies dependencies;
+        add_dialog_dependencies(dependencies, dialog_id);
+        add_message_dependencies(dependencies, dialog_id, m.get());
+        resolve_dependencies_force(dependencies);
+
+        m->content = dup_message_content(dialog_id, m->content.get(), false);
+
+        auto result_message = continue_send_message(dialog_id, std::move(m), event.id_);
+        if (result_message != nullptr) {
+          do_send_message(dialog_id, result_message);
+        }
+        break;
+      }
+      case LogEvent::HandlerType::SendBotStartMessage: {
+        if (!G()->parameters().use_message_db) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        SendBotStartMessageLogEvent log_event;
+        log_event_parse(log_event, event.data_).ensure();
+
+        auto dialog_id = log_event.dialog_id;
+        auto m = std::move(log_event.m_out);
+        m->send_message_logevent_id = event.id_;
+
+        CHECK(m->content->get_id() == MessageText::ID);
+
+        Dependencies dependencies;
+        add_dialog_dependencies(dependencies, dialog_id);
+        add_message_dependencies(dependencies, dialog_id, m.get());
+        resolve_dependencies_force(dependencies);
+
+        auto bot_user_id = log_event.bot_user_id;
+        if (!td_->contacts_manager_->have_user_force(bot_user_id)) {
+          LOG(ERROR) << "Can't find bot " << bot_user_id;
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          continue;
+        }
+
+        auto result_message = continue_send_message(dialog_id, std::move(m), event.id_);
+        if (result_message != nullptr) {
+          do_send_bot_start_message(bot_user_id, dialog_id, log_event.parameter, result_message);
+        }
+        break;
+      }
+      case LogEvent::HandlerType::SendInlineQueryResultMessage: {
+        if (!G()->parameters().use_message_db) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        SendInlineQueryResultMessageLogEvent log_event;
+        log_event_parse(log_event, event.data_).ensure();
+
+        auto dialog_id = log_event.dialog_id;
+        auto m = std::move(log_event.m_out);
+        m->send_message_logevent_id = event.id_;
+
+        if (m->content->get_id() == MessageUnsupported::ID) {
+          LOG(ERROR) << "Message content is invalid: " << format::as_hex_dump<4>(Slice(event.data_));
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          continue;
+        }
+
+        Dependencies dependencies;
+        add_dialog_dependencies(dependencies, dialog_id);
+        add_message_dependencies(dependencies, dialog_id, m.get());
+        resolve_dependencies_force(dependencies);
+
+        m->content = dup_message_content(dialog_id, m->content.get(), false);
+
+        auto result_message = continue_send_message(dialog_id, std::move(m), event.id_);
+        if (result_message != nullptr) {
+          do_send_inline_query_result_message(dialog_id, result_message, log_event.query_id, log_event.result_id);
+        }
+        break;
+      }
+      case LogEvent::HandlerType::SendScreenshotTakenNotificationMessage: {
+        if (!G()->parameters().use_message_db) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        SendScreenshotTakenNotificationMessageLogEvent log_event;
+        log_event_parse(log_event, event.data_).ensure();
+
+        auto dialog_id = log_event.dialog_id;
+        auto m = std::move(log_event.m_out);
+        m->send_message_logevent_id = 0;
+
+        CHECK(m->content->get_id() == MessageScreenshotTaken::ID);
+
+        Dependencies dependencies;
+        add_dialog_dependencies(dependencies, dialog_id);
+        add_message_dependencies(dependencies, dialog_id, m.get());
+        resolve_dependencies_force(dependencies);
+
+        auto result_message = continue_send_message(dialog_id, std::move(m), event.id_);
+        if (result_message != nullptr) {
+          do_send_screenshot_taken_notification_message(dialog_id, result_message, event.id_);
+        }
+        break;
+      }
+      case LogEvent::HandlerType::ForwardMessages: {
+        if (!G()->parameters().use_message_db) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        ForwardMessagesLogEvent log_event;
+        log_event_parse(log_event, event.data_).ensure();
+
+        auto to_dialog_id = log_event.to_dialog_id;
+        auto from_dialog_id = log_event.from_dialog_id;
+        auto messages = std::move(log_event.messages_out);
+
+        Dependencies dependencies;
+        add_dialog_dependencies(dependencies, to_dialog_id);
+        add_dialog_dependencies(dependencies, from_dialog_id);
+        for (auto &m : messages) {
+          add_message_dependencies(dependencies, to_dialog_id, m.get());
+        }
+        resolve_dependencies_force(dependencies);
+
+        Dialog *to_dialog = get_dialog_force(to_dialog_id);
+        if (to_dialog == nullptr) {
+          LOG(ERROR) << "Can't find " << to_dialog_id << " to forward messages to";
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          continue;
+        }
+        Dialog *from_dialog = get_dialog_force(from_dialog_id);
+        if (from_dialog == nullptr) {
+          LOG(ERROR) << "Can't find " << from_dialog_id << " to forward messages from";
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          continue;
+        }
+        for (auto &m : messages) {
+          m->message_id = get_next_yet_unsent_message_id(to_dialog);
+          m->random_y = get_random_y(m->message_id);
+          m->date = G()->unix_time();
+          m->content = dup_message_content(to_dialog_id, m->content.get(), true);
+          m->have_previous = true;
+          m->have_next = true;
+        }
+
+        LOG(INFO) << "Continue to forward " << messages.size() << " messages to " << to_dialog_id << " from binlog";
+
+        if (!have_input_peer(from_dialog_id, AccessRights::Read) || can_send_message(to_dialog_id).is_error()) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        bool need_update = false;
+        bool need_update_dialog_pos = false;
+        vector<Message *> forwarded_messages;
+        for (auto &m : messages) {
+          message_random_ids_.insert(m->random_id);
+          forwarded_messages.push_back(add_message_to_dialog(to_dialog, std::move(m), false, &need_update,
+                                                             &need_update_dialog_pos, "forward message again"));
+          send_update_new_message(to_dialog, forwarded_messages.back());
+        }
+        if (need_update_dialog_pos) {
+          send_update_chat_last_message(to_dialog, "on_reforward_message");
+        }
+
+        do_forward_messages(to_dialog_id, from_dialog_id, forwarded_messages, log_event.message_ids, event.id_);
+        break;
+      }
+      case LogEvent::HandlerType::DeleteMessage: {
+        if (!G()->parameters().use_message_db) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        DeleteMessageLogEvent log_event;
+        log_event_parse(log_event, event.data_).ensure();
+        log_event.id_ = event.id_;
+        do_delete_message_logevent(log_event);
+        break;
+      }
+      case LogEvent::HandlerType::DeleteMessagesFromServer: {
+        if (!G()->parameters().use_message_db) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        DeleteMessagesFromServerLogEvent log_event;
+        log_event_parse(log_event, event.data_).ensure();
+
+        auto dialog_id = log_event.dialog_id_;
+        Dialog *d = get_dialog_force(dialog_id);
+        if (d == nullptr || !have_input_peer(dialog_id, AccessRights::Read)) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        delete_messages_from_server(dialog_id, std::move(log_event.message_ids_), log_event.revoke_, event.id_, Auto());
+        break;
+      }
+      case LogEvent::HandlerType::DeleteDialogHistoryFromServer: {
+        if (!G()->parameters().use_message_db) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        DeleteDialogHistoryFromServerLogEvent log_event;
+        log_event_parse(log_event, event.data_).ensure();
+
+        auto dialog_id = log_event.dialog_id_;
+        Dialog *d = get_dialog_force(dialog_id);
+        if (d == nullptr || !have_input_peer(dialog_id, AccessRights::Read)) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        delete_dialog_history_from_server(dialog_id, log_event.max_message_id_, log_event.remove_from_dialog_list_,
+                                          true, event.id_, Auto());
+        break;
+      }
+      case LogEvent::HandlerType::DeleteAllChannelMessagesFromUserOnServer: {
+        if (!G()->parameters().use_chat_info_db) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        DeleteAllChannelMessagesFromUserOnServerLogEvent log_event;
+        log_event_parse(log_event, event.data_).ensure();
+
+        auto channel_id = log_event.channel_id_;
+        if (!td_->contacts_manager_->have_channel_force(channel_id)) {
+          LOG(ERROR) << "Can't find " << channel_id;
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        auto user_id = log_event.user_id_;
+        if (!td_->contacts_manager_->have_user_force(user_id)) {
+          LOG(ERROR) << "Can't find user " << user_id;
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        delete_all_channel_messages_from_user_on_server(channel_id, user_id, event.id_, Auto());
+        break;
+      }
+      case LogEvent::HandlerType::ReadHistoryOnServer: {
+        if (!G()->parameters().use_message_db) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        ReadHistoryOnServerLogEvent log_event;
+        log_event_parse(log_event, event.data_).ensure();
+
+        auto dialog_id = log_event.dialog_id_;
+        Dialog *d = get_dialog_force(dialog_id);
+        if (d == nullptr || !have_input_peer(dialog_id, AccessRights::Read)) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        read_history_on_server(dialog_id, log_event.max_message_id_, true, event.id_);
+        break;
+      }
+      case LogEvent::HandlerType::ReadMessageContentsOnServer: {
+        if (!G()->parameters().use_message_db) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        ReadMessageContentsOnServerLogEvent log_event;
+        log_event_parse(log_event, event.data_).ensure();
+
+        auto dialog_id = log_event.dialog_id_;
+        Dialog *d = get_dialog_force(dialog_id);
+        if (d == nullptr || !have_input_peer(dialog_id, AccessRights::Read)) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        read_message_contents_on_server(dialog_id, std::move(log_event.message_ids_), event.id_);
+        break;
+      }
+      case LogEvent::HandlerType::ReadAllDialogMentionsOnServer: {
+        if (!G()->parameters().use_message_db) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        ReadAllDialogMentionsOnServerLogEvent log_event;
+        log_event_parse(log_event, event.data_).ensure();
+
+        auto dialog_id = log_event.dialog_id_;
+        Dialog *d = get_dialog_force(dialog_id);
+        if (d == nullptr || !have_input_peer(dialog_id, AccessRights::Read)) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        read_all_dialog_mentions_on_server(dialog_id, event.id_, Promise<Unit>());
+        break;
+      }
+      case LogEvent::HandlerType::ToggleDialogIsPinnedOnServer: {
+        if (!G()->parameters().use_message_db) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        ToggleDialogIsPinnedOnServerLogEvent log_event;
+        log_event_parse(log_event, event.data_).ensure();
+
+        auto dialog_id = log_event.dialog_id_;
+        Dialog *d = get_dialog_force(dialog_id);
+        if (d == nullptr || !have_input_peer(dialog_id, AccessRights::Read)) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        toggle_dialog_is_pinned_on_server(dialog_id, log_event.is_pinned_, event.id_);
+        break;
+      }
+      case LogEvent::HandlerType::ReorderPinnedDialogsOnServer: {
+        if (!G()->parameters().use_message_db) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        ReorderPinnedDialogsOnServerLogEvent log_event;
+        log_event_parse(log_event, event.data_).ensure();
+
+        vector<DialogId> dialog_ids;
+        for (auto &dialog_id : log_event.dialog_ids_) {
+          Dialog *d = get_dialog_force(dialog_id);
+          if (d != nullptr && have_input_peer(dialog_id, AccessRights::Read)) {
+            dialog_ids.push_back(dialog_id);
+          }
+        }
+        if (dialog_ids.empty()) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        reorder_pinned_dialogs_on_server(dialog_ids, event.id_);
+        break;
+      }
+      case LogEvent::HandlerType::SaveDialogDraftMessageOnServer: {
+        if (!G()->parameters().use_message_db) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+
+        SaveDialogDraftMessageOnServerLogEvent log_event;
+        log_event_parse(log_event, event.data_).ensure();
+
+        auto dialog_id = log_event.dialog_id_;
+        Dialog *d = get_dialog_force(dialog_id);
+        if (d == nullptr || !have_input_peer(dialog_id, AccessRights::Write)) {
+          BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+          break;
+        }
+        d->save_draft_message_logevent_id = event.id_;
+
+        save_dialog_draft_message_on_server(dialog_id);
+        break;
+      }
+      case LogEvent::HandlerType::GetChannelDifference: {
+        GetChannelDifferenceLogEvent log_event;
+        log_event_parse(log_event, event.data_).ensure();
+
+        DialogId dialog_id(log_event.channel_id);
+        LOG(INFO) << "Continue to run getChannelDifference in " << dialog_id;
+        get_channel_difference_to_logevent_id_.emplace(dialog_id, event.id_);
+        do_get_channel_difference(
+            dialog_id, load_channel_pts(dialog_id), true,
+            telegram_api::make_object<telegram_api::inputChannel>(log_event.channel_id.get(), log_event.access_hash),
+            "LogEvent::HandlerType::GetChannelDifference");
+        break;
+      }
+      default:
+        LOG(FATAL) << "Unsupported logevent type " << event.type_;
+    }
+  }
+}
+
+void MessagesManager::save_recently_found_dialogs() {
+  if (recently_found_dialogs_loaded_ < 2) {
+    return;
+  }
+
+  string value;
+  for (auto &dialog_id : recently_found_dialog_ids_) {
+    if (!value.empty()) {
+      value += ',';
+    }
+    if (!G()->parameters().use_message_db) {
+      // if there is no dialog database, prefer to save dialogs by username
+      auto username = get_dialog_username(dialog_id);
+      if (dialog_id.get_type() != DialogType::SecretChat && !username.empty()) {
+        value += '@';
+        value += username;
+        continue;
+      }
+    }
+    value += to_string(dialog_id.get());
+  }
+  G()->td_db()->get_binlog_pmc()->set("recently_found_dialog_usernames_and_ids", value);
+}
+
+bool MessagesManager::load_recently_found_dialogs(Promise<Unit> &promise) {
+  if (recently_found_dialogs_loaded_ >= 2) {
+    return true;
+  }
+
+  string found_dialogs_str = G()->td_db()->get_binlog_pmc()->get("recently_found_dialog_usernames_and_ids");
+  auto found_dialogs = full_split(found_dialogs_str, ',');
+  if (found_dialogs.empty()) {
+    recently_found_dialogs_loaded_ = 2;
+    if (!recently_found_dialog_ids_.empty()) {
+      save_recently_found_dialogs();
+    }
+    return true;
+  }
+
+  if (recently_found_dialogs_loaded_ == 1 && resolve_recent_found_dialogs_multipromise_.promise_count() == 0) {
+    // queries was sent and have already been finished
+    auto newly_found_dialogs = std::move(recently_found_dialog_ids_);
+    recently_found_dialog_ids_.clear();
+
+    for (auto it = found_dialogs.rbegin(); it != found_dialogs.rend(); ++it) {
+      if ((*it)[0] == '@') {
+        auto dialog_id = resolve_dialog_username(it->substr(1));
+        if (dialog_id.is_valid() && have_input_peer(dialog_id, AccessRights::Read)) {
+          force_create_dialog(dialog_id, "recently found resolved dialog");
+          add_recently_found_dialog_internal(dialog_id);
+        }
+      } else {
+        auto dialog_id = DialogId(to_integer<int64>(*it));
+        CHECK(dialog_id.is_valid());
+        if (have_input_peer(dialog_id, AccessRights::Read)) {
+          force_create_dialog(dialog_id, "recently found dialog");
+          add_recently_found_dialog_internal(dialog_id);
+        }
+      }
+    }
+    for (auto it = newly_found_dialogs.rbegin(); it != newly_found_dialogs.rend(); ++it) {
+      add_recently_found_dialog_internal(*it);
+    }
+    recently_found_dialogs_loaded_ = 2;
+    if (!newly_found_dialogs.empty()) {
+      save_recently_found_dialogs();
+    }
+    return true;
+  }
+
+  resolve_recent_found_dialogs_multipromise_.add_promise(std::move(promise));
+  if (recently_found_dialogs_loaded_ == 0) {
+    recently_found_dialogs_loaded_ = 1;
+
+    resolve_recent_found_dialogs_multipromise_.set_ignore_errors(true);
+
+    for (auto &found_dialog : found_dialogs) {
+      if (found_dialog[0] == '@') {
+        search_public_dialog(found_dialog, false, resolve_recent_found_dialogs_multipromise_.get_promise());
+      }
+    }
+    if (G()->parameters().use_message_db) {
+      for (auto &found_dialog : found_dialogs) {
+        if (found_dialog[0] != '@') {
+          auto dialog_id = DialogId(to_integer<int64>(found_dialog));
+          CHECK(dialog_id.is_valid());
+          // TODO use asynchronous load
+          // get_dialog(dialog_id, resolve_recent_found_dialogs_multipromise_.get_promise());
+          get_dialog_force(dialog_id);
+        }
+      }
+      resolve_recent_found_dialogs_multipromise_.get_promise().set_value(Unit());
+    } else {
+      get_dialogs(MIN_DIALOG_DATE, MAX_GET_DIALOGS, false, resolve_recent_found_dialogs_multipromise_.get_promise());
+      td_->contacts_manager_->search_contacts("", 1, resolve_recent_found_dialogs_multipromise_.get_promise());
+    }
+  }
+  return false;
+}
+
+Status MessagesManager::add_recently_found_dialog(DialogId dialog_id) {
+  if (!have_dialog_force(dialog_id)) {
+    return Status::Error(5, "Chat not found");
+  }
+  if (add_recently_found_dialog_internal(dialog_id)) {
+    save_recently_found_dialogs();
+  }
+
+  return Status::OK();
+}
+
+Status MessagesManager::remove_recently_found_dialog(DialogId dialog_id) {
+  if (!have_dialog_force(dialog_id)) {
+    return Status::Error(5, "Chat not found");
+  }
+  if (remove_recently_found_dialog_internal(dialog_id)) {
+    save_recently_found_dialogs();
+  }
+
+  return Status::OK();
+}
+
+void MessagesManager::clear_recently_found_dialogs() {
+  recently_found_dialogs_loaded_ = 2;
+  if (recently_found_dialog_ids_.empty()) {
+    return;
+  }
+
+  recently_found_dialog_ids_.clear();
+  save_recently_found_dialogs();
+}
+
+bool MessagesManager::add_recently_found_dialog_internal(DialogId dialog_id) {
+  CHECK(have_dialog(dialog_id));
+
+  if (!recently_found_dialog_ids_.empty() && recently_found_dialog_ids_[0] == dialog_id) {
+    return false;
+  }
+
+  // TODO create function
+  auto it = std::find(recently_found_dialog_ids_.begin(), recently_found_dialog_ids_.end(), dialog_id);
+  if (it == recently_found_dialog_ids_.end()) {
+    if (narrow_cast<int32>(recently_found_dialog_ids_.size()) == MAX_RECENT_FOUND_DIALOGS) {
+      CHECK(!recently_found_dialog_ids_.empty());
+      recently_found_dialog_ids_.back() = dialog_id;
+    } else {
+      recently_found_dialog_ids_.push_back(dialog_id);
+    }
+    it = recently_found_dialog_ids_.end() - 1;
+  }
+  std::rotate(recently_found_dialog_ids_.begin(), it, it + 1);
+  return true;
+}
+
+bool MessagesManager::remove_recently_found_dialog_internal(DialogId dialog_id) {
+  CHECK(have_dialog(dialog_id));
+
+  auto it = std::find(recently_found_dialog_ids_.begin(), recently_found_dialog_ids_.end(), dialog_id);
+  if (it == recently_found_dialog_ids_.end()) {
+    return false;
+  }
+  recently_found_dialog_ids_.erase(it);
+  return true;
+}
+
+void MessagesManager::suffix_load_loop(Dialog *d) {
+  if (d->suffix_load_has_query_) {
+    return;
+  }
+
+  if (d->suffix_load_queries_.empty()) {
+    return;
+  }
+  CHECK(!d->suffix_load_done_);
+
+  // Send db query
+  LOG(INFO) << "suffix_load send query " << d->dialog_id;
+  auto promise = PromiseCreator::lambda([actor_id = actor_id(this), dialog_id = d->dialog_id](Result<Unit> result) {
+    send_closure(actor_id, &MessagesManager::suffix_load_query_ready, dialog_id);
+  });
+  d->suffix_load_query_message_id_ = d->suffix_load_first_message_id_;
+  if (d->suffix_load_first_message_id_.is_valid()) {
+    get_history(d->dialog_id, d->suffix_load_first_message_id_, -1, 100, true, true, std::move(promise));
+  } else {
+    get_history_from_the_end(d->dialog_id, true, true, std::move(promise));
+  }
+  d->suffix_load_has_query_ = true;
+}
+
+void MessagesManager::suffix_load_update_first_message_id(Dialog *d) {
+  // Update first_message_id
+  if (!d->suffix_load_first_message_id_.is_valid()) {
+    d->suffix_load_first_message_id_ = d->last_message_id;
+  }
+  if (!d->suffix_load_first_message_id_.is_valid() && !d->suffix_load_was_query_) {
+    return;
+  }
+  auto it = d->suffix_load_first_message_id_.is_valid() ? MessagesConstIterator(d, d->suffix_load_first_message_id_)
+                                                        : MessagesConstIterator(d, MessageId::max());
+  while (*it && (*it)->have_previous) {
+    --it;
+  }
+  if (*it) {
+    d->suffix_load_first_message_id_ = (*it)->message_id;
+  } else {
+    d->suffix_load_first_message_id_ = MessageId();
+  }
+}
+
+void MessagesManager::suffix_load_query_ready(DialogId dialog_id) {
+  LOG(INFO) << "suffix_load_query_ready " << dialog_id;
+  auto *d = get_dialog(dialog_id);
+  CHECK(d != nullptr);
+  d->suffix_load_was_query_ = true;
+  suffix_load_update_first_message_id(d);
+  if (d->suffix_load_first_message_id_ == d->suffix_load_query_message_id_) {
+    LOG(INFO) << "suffix_load done " << dialog_id;
+    d->suffix_load_done_ = true;
+  }
+  d->suffix_load_has_query_ = false;
+
+  // Remove ready queries
+  auto *m = get_message_force(d, d->suffix_load_first_message_id_);
+  auto ready_it = std::partition(d->suffix_load_queries_.begin(), d->suffix_load_queries_.end(),
+                                 [&](auto &value) { return !(d->suffix_load_done_ || value.second(m)); });
+  for (auto it = ready_it; it != d->suffix_load_queries_.end(); it++) {
+    it->first.set_value(Unit());
+  }
+  d->suffix_load_queries_.erase(ready_it, d->suffix_load_queries_.end());
+
+  suffix_load_loop(d);
+}
+
+void MessagesManager::suffix_load_add_query(Dialog *d,
+                                            std::pair<Promise<>, std::function<bool(const Message *)>> query) {
+  suffix_load_update_first_message_id(d);
+  auto *m = get_message_force(d, d->suffix_load_first_message_id_);
+  if (d->suffix_load_done_ || query.second(m)) {
+    query.first.set_value(Unit());
+  } else {
+    d->suffix_load_queries_.emplace_back(std::move(query));
+    suffix_load_loop(d);
+  }
+}
+
+void MessagesManager::suffix_load_till_date(Dialog *d, int32 date, Promise<> promise) {
+  LOG(INFO) << "suffix_load_till_date " << d->dialog_id << tag("date", date);
+  auto condition = [date](const Message *m) { return m && m->date < date; };
+  suffix_load_add_query(d, std::make_pair(std::move(promise), std::move(condition)));
+}
+
+void MessagesManager::suffix_load_till_message_id(Dialog *d, MessageId message_id, Promise<> promise) {
+  LOG(INFO) << "suffix_load_till_message_id " << d->dialog_id << " " << message_id;
+  auto condition = [message_id](const Message *m) { return m && m->message_id.get() < message_id.get(); };
+  suffix_load_add_query(d, std::make_pair(std::move(promise), std::move(condition)));
+}
+
+Result<ServerMessageId> MessagesManager::get_invoice_message_id(FullMessageId full_message_id) {
+  auto message = get_message_force(full_message_id);
+  if (message == nullptr) {
+    return Status::Error(5, "Message not found");
+  }
+  if (message->content->get_id() != MessageInvoice::ID) {
+    return Status::Error(5, "Message has no invoice");
+  }
+  auto message_id = full_message_id.get_message_id();
+  if (!message_id.is_server()) {
+    return Status::Error(5, "Wrong message identifier");
+  }
+  // TODO need to check that message is not forwarded
+
+  return message_id.get_server_message_id();
+}
+
+void MessagesManager::get_payment_form(FullMessageId full_message_id,
+                                       Promise<tl_object_ptr<td_api::paymentForm>> &&promise) {
+  auto r_message_id = get_invoice_message_id(full_message_id);
+  if (r_message_id.is_error()) {
+    return promise.set_error(r_message_id.move_as_error());
+  }
+
+  td::get_payment_form(r_message_id.ok(), std::move(promise));
+}
+
+void MessagesManager::validate_order_info(FullMessageId full_message_id, tl_object_ptr<td_api::orderInfo> order_info,
+                                          bool allow_save,
+                                          Promise<tl_object_ptr<td_api::validatedOrderInfo>> &&promise) {
+  auto r_message_id = get_invoice_message_id(full_message_id);
+  if (r_message_id.is_error()) {
+    return promise.set_error(r_message_id.move_as_error());
+  }
+
+  td::validate_order_info(r_message_id.ok(), std::move(order_info), allow_save, std::move(promise));
+}
+
+void MessagesManager::send_payment_form(FullMessageId full_message_id, const string &order_info_id,
+                                        const string &shipping_option_id,
+                                        const tl_object_ptr<td_api::InputCredentials> &credentials,
+                                        Promise<tl_object_ptr<td_api::paymentResult>> &&promise) {
+  auto r_message_id = get_invoice_message_id(full_message_id);
+  if (r_message_id.is_error()) {
+    return promise.set_error(r_message_id.move_as_error());
+  }
+
+  td::send_payment_form(r_message_id.ok(), order_info_id, shipping_option_id, credentials, std::move(promise));
+}
+
+void MessagesManager::get_payment_receipt(FullMessageId full_message_id,
+                                          Promise<tl_object_ptr<td_api::paymentReceipt>> &&promise) {
+  auto message = get_message_force(full_message_id);
+  if (message == nullptr) {
+    return promise.set_error(Status::Error(5, "Message not found"));
+  }
+  if (message->content->get_id() != MessagePaymentSuccessful::ID) {
+    return promise.set_error(Status::Error(5, "Message has wrong type"));
+  }
+  auto message_id = full_message_id.get_message_id();
+  if (!message_id.is_server()) {
+    return promise.set_error(Status::Error(5, "Wrong message identifier"));
+  }
+
+  td::get_payment_receipt(message_id.get_server_message_id(), std::move(promise));
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/MessagesManager.h b/libs/tdlib/td/td/telegram/MessagesManager.h
new file mode 100644
index 0000000000..7b4d84254f
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/MessagesManager.h
@@ -0,0 +1,2740 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/MultiPromise.h"
+#include "td/actor/PromiseFuture.h"
+#include "td/actor/SignalSlot.h"
+#include "td/actor/Timeout.h"
+
+#include "td/db/binlog/BinlogEvent.h"
+
+#include "td/telegram/AccessRights.h"
+#include "td/telegram/CallDiscardReason.h"
+#include "td/telegram/ChannelId.h"
+#include "td/telegram/ChatId.h"
+#include "td/telegram/Contact.h"
+#include "td/telegram/DialogId.h"
+#include "td/telegram/DialogParticipant.h"
+#include "td/telegram/DocumentsManager.h"
+#include "td/telegram/files/FileId.h"
+#include "td/telegram/Game.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/Location.h"
+#include "td/telegram/MessageEntity.h"
+#include "td/telegram/MessageId.h"
+#include "td/telegram/MessagesDb.h"
+#include "td/telegram/net/NetQuery.h"
+#include "td/telegram/Payments.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/ReplyMarkup.h"
+#include "td/telegram/SecretChatId.h"
+#include "td/telegram/SecretInputMedia.h"
+#include "td/telegram/UserId.h"
+#include "td/telegram/WebPageId.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/ChangesProcessor.h"
+#include "td/utils/common.h"
+#include "td/utils/Heap.h"
+#include "td/utils/Hints.h"
+#include "td/utils/logging.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tl_storers.h"
+
+#include <array>
+#include <functional>
+#include <limits>
+#include <map>
+#include <memory>
+#include <set>
+#include <unordered_map>
+#include <unordered_set>
+#include <utility>
+
+namespace td {
+
+class Td;
+
+class MultiSequenceDispatcher;
+
+// Do not forget to update MessagesManager::update_message_content when one of the inheritors of this class changes
+class MessageContent {
+ public:
+  virtual int32 get_id() const = 0;
+  virtual ~MessageContent() = default;
+};
+
+class MessageText : public MessageContent {
+ public:
+  FormattedText text;
+  WebPageId web_page_id;
+
+  MessageText() = default;
+  MessageText(FormattedText text, WebPageId web_page_id) : text(std::move(text)), web_page_id(web_page_id) {
+  }
+
+  static const int32 ID = 0;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageAnimation : public MessageContent {
+ public:
+  FileId file_id;
+
+  FormattedText caption;
+
+  MessageAnimation() = default;
+  MessageAnimation(FileId file_id, FormattedText &&caption) : file_id(file_id), caption(std::move(caption)) {
+  }
+
+  static const int32 ID = 1;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageAudio : public MessageContent {
+ public:
+  FileId file_id;
+
+  FormattedText caption;
+
+  MessageAudio() = default;
+  MessageAudio(FileId file_id, FormattedText &&caption) : file_id(file_id), caption(std::move(caption)) {
+  }
+
+  static const int32 ID = 2;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageDocument : public MessageContent {
+ public:
+  FileId file_id;
+
+  FormattedText caption;
+
+  MessageDocument() = default;
+  MessageDocument(FileId file_id, FormattedText &&caption) : file_id(file_id), caption(std::move(caption)) {
+  }
+
+  static const int32 ID = 3;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessagePhoto : public MessageContent {
+ public:
+  Photo photo;
+
+  FormattedText caption;
+
+  MessagePhoto() = default;
+  MessagePhoto(Photo &&photo, FormattedText &&caption) : photo(std::move(photo)), caption(std::move(caption)) {
+  }
+
+  static const int32 ID = 4;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageSticker : public MessageContent {
+ public:
+  FileId file_id;
+
+  MessageSticker() = default;
+  explicit MessageSticker(FileId file_id) : file_id(file_id) {
+  }
+
+  static const int32 ID = 5;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageVideo : public MessageContent {
+ public:
+  FileId file_id;
+
+  FormattedText caption;
+
+  MessageVideo() = default;
+  MessageVideo(FileId file_id, FormattedText &&caption) : file_id(file_id), caption(std::move(caption)) {
+  }
+
+  static const int32 ID = 6;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageVoiceNote : public MessageContent {
+ public:
+  FileId file_id;
+
+  FormattedText caption;
+  bool is_listened;
+
+  MessageVoiceNote() = default;
+  MessageVoiceNote(FileId file_id, FormattedText &&caption, bool is_listened)
+      : file_id(file_id), caption(std::move(caption)), is_listened(is_listened) {
+  }
+
+  static const int32 ID = 7;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageContact : public MessageContent {
+ public:
+  Contact contact;
+
+  MessageContact() = default;
+  explicit MessageContact(Contact &&contact) : contact(std::move(contact)) {
+  }
+
+  static const int32 ID = 8;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageLocation : public MessageContent {
+ public:
+  Location location;
+
+  MessageLocation() = default;
+  explicit MessageLocation(Location &&location) : location(std::move(location)) {
+  }
+
+  static const int32 ID = 9;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageVenue : public MessageContent {
+ public:
+  Venue venue;
+
+  MessageVenue() = default;
+  explicit MessageVenue(Venue &&venue) : venue(std::move(venue)) {
+  }
+
+  static const int32 ID = 10;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageChatCreate : public MessageContent {
+ public:
+  string title;
+  vector<UserId> participant_user_ids;
+
+  MessageChatCreate() = default;
+  MessageChatCreate(string &&title, vector<UserId> &&participant_user_ids)
+      : title(std::move(title)), participant_user_ids(std::move(participant_user_ids)) {
+  }
+
+  static const int32 ID = 11;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageChatChangeTitle : public MessageContent {
+ public:
+  string title;
+
+  MessageChatChangeTitle() = default;
+  explicit MessageChatChangeTitle(string &&title) : title(std::move(title)) {
+  }
+
+  static const int32 ID = 12;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageChatChangePhoto : public MessageContent {
+ public:
+  Photo photo;
+
+  MessageChatChangePhoto() = default;
+  explicit MessageChatChangePhoto(Photo &&photo) : photo(std::move(photo)) {
+  }
+
+  static const int32 ID = 13;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageChatDeletePhoto : public MessageContent {
+ public:
+  static const int32 ID = 14;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageChatDeleteHistory : public MessageContent {
+ public:
+  static const int32 ID = 15;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageChatAddUsers : public MessageContent {
+ public:
+  vector<UserId> user_ids;
+
+  MessageChatAddUsers() = default;
+  explicit MessageChatAddUsers(vector<UserId> &&user_ids) : user_ids(std::move(user_ids)) {
+  }
+
+  static const int32 ID = 16;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageChatJoinedByLink : public MessageContent {
+ public:
+  static const int32 ID = 17;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageChatDeleteUser : public MessageContent {
+ public:
+  UserId user_id;
+
+  MessageChatDeleteUser() = default;
+  explicit MessageChatDeleteUser(UserId user_id) : user_id(user_id) {
+  }
+
+  static const int32 ID = 18;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageChatMigrateTo : public MessageContent {
+ public:
+  ChannelId migrated_to_channel_id;
+
+  MessageChatMigrateTo() = default;
+  explicit MessageChatMigrateTo(ChannelId migrated_to_channel_id) : migrated_to_channel_id(migrated_to_channel_id) {
+  }
+
+  static const int32 ID = 19;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageChannelCreate : public MessageContent {
+ public:
+  string title;
+
+  MessageChannelCreate() = default;
+  explicit MessageChannelCreate(string &&title) : title(std::move(title)) {
+  }
+
+  static const int32 ID = 20;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageChannelMigrateFrom : public MessageContent {
+ public:
+  string title;
+  ChatId migrated_from_chat_id;
+
+  MessageChannelMigrateFrom() = default;
+  MessageChannelMigrateFrom(string &&title, ChatId migrated_from_chat_id)
+      : title(std::move(title)), migrated_from_chat_id(migrated_from_chat_id) {
+  }
+
+  static const int32 ID = 21;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessagePinMessage : public MessageContent {
+ public:
+  MessageId message_id;
+
+  MessagePinMessage() = default;
+  explicit MessagePinMessage(MessageId message_id) : message_id(message_id) {
+  }
+
+  static const int32 ID = 22;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageGame : public MessageContent {
+ public:
+  Game game;
+
+  MessageGame() = default;
+  explicit MessageGame(Game &&game) : game(std::move(game)) {
+  }
+
+  static const int32 ID = 23;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageGameScore : public MessageContent {
+ public:
+  MessageId game_message_id;
+  int64 game_id;
+  int32 score;
+
+  MessageGameScore() = default;
+  MessageGameScore(MessageId game_message_id, int64 game_id, int32 score)
+      : game_message_id(game_message_id), game_id(game_id), score(score) {
+  }
+
+  static const int32 ID = 24;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageScreenshotTaken : public MessageContent {
+ public:
+  static const int32 ID = 25;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageChatSetTtl : public MessageContent {
+ public:
+  int32 ttl;
+
+  MessageChatSetTtl() = default;
+  explicit MessageChatSetTtl(int32 ttl) : ttl(ttl) {
+  }
+
+  static const int32 ID = 26;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageUnsupported
+    : public MessageContent {  // TODO save a layer in which the message was received to
+                               // automatically reget it if the layer changes
+ public:
+  static const int32 ID = 27;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageCall : public MessageContent {
+ public:
+  int64 call_id;
+  int32 duration;
+  CallDiscardReason discard_reason;
+
+  MessageCall() = default;
+  MessageCall(int64 call_id, int32 duration, CallDiscardReason discard_reason)
+      : call_id(call_id), duration(duration), discard_reason(discard_reason) {
+  }
+
+  static const int32 ID = 28;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageInvoice : public MessageContent {
+ public:
+  string title;
+  string description;
+  Photo photo;
+  string start_parameter;
+
+  // InputMessageInvoice
+  Invoice invoice;
+  string payload;
+  string provider_token;
+  string provider_data;
+
+  // MessageInvoice
+  int64 total_amount = 0;
+  MessageId receipt_message_id;
+
+  MessageInvoice() = default;
+  MessageInvoice(string &&title, string &&description, Photo &&photo, string &&start_parameter, int64 total_amount,
+                 string &&currency, bool is_test, bool need_shipping_address, MessageId receipt_message_id)
+      : title(std::move(title))
+      , description(std::move(description))
+      , photo(std::move(photo))
+      , start_parameter(std::move(start_parameter))
+      , invoice(std::move(currency), is_test, need_shipping_address)
+      , payload()
+      , provider_token()
+      , provider_data()
+      , total_amount(total_amount)
+      , receipt_message_id(receipt_message_id) {
+  }
+
+  static const int32 ID = 29;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessagePaymentSuccessful : public MessageContent {
+ public:
+  MessageId invoice_message_id;
+  string currency;
+  int64 total_amount = 0;
+
+  // bots only part
+  string invoice_payload;
+  string shipping_option_id;
+  unique_ptr<OrderInfo> order_info;
+  string telegram_payment_charge_id;
+  string provider_payment_charge_id;
+
+  MessagePaymentSuccessful() = default;
+  MessagePaymentSuccessful(MessageId invoice_message_id, string &&currency, int64 total_amount)
+      : invoice_message_id(invoice_message_id), currency(std::move(currency)), total_amount(total_amount) {
+  }
+
+  static const int32 ID = 30;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageVideoNote : public MessageContent {
+ public:
+  FileId file_id;
+
+  bool is_viewed = false;
+
+  MessageVideoNote() = default;
+  MessageVideoNote(FileId file_id, bool is_viewed) : file_id(file_id), is_viewed(is_viewed) {
+  }
+
+  static const int32 ID = 31;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageContactRegistered : public MessageContent {
+ public:
+  static const int32 ID = 32;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageExpiredPhoto : public MessageContent {
+ public:
+  MessageExpiredPhoto() = default;
+
+  static const int32 ID = 33;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageExpiredVideo : public MessageContent {
+ public:
+  MessageExpiredVideo() = default;
+
+  static const int32 ID = 34;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageLiveLocation : public MessageContent {
+ public:
+  Location location;
+  int32 period;
+
+  MessageLiveLocation() = default;
+  MessageLiveLocation(Location &&location, int32 period) : location(std::move(location)), period(period) {
+  }
+
+  static const int32 ID = 35;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageCustomServiceAction : public MessageContent {
+ public:
+  string message;
+
+  MessageCustomServiceAction() = default;
+  explicit MessageCustomServiceAction(string &&message) : message(std::move(message)) {
+  }
+
+  static const int32 ID = 36;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class MessageWebsiteConnected : public MessageContent {
+ public:
+  string domain_name;
+
+  MessageWebsiteConnected() = default;
+  explicit MessageWebsiteConnected(string &&domain_name) : domain_name(std::move(domain_name)) {
+  }
+
+  static const int32 ID = 37;
+  int32 get_id() const override {
+    return ID;
+  }
+};
+
+class InputMessageText {
+ public:
+  FormattedText text;
+  bool disable_web_page_preview = false;
+  bool clear_draft = false;
+  InputMessageText() = default;
+  InputMessageText(FormattedText text, bool disable_web_page_preview, bool clear_draft)
+      : text(std::move(text)), disable_web_page_preview(disable_web_page_preview), clear_draft(clear_draft) {
+  }
+};
+
+bool operator==(const InputMessageText &lhs, const InputMessageText &rhs);
+bool operator!=(const InputMessageText &lhs, const InputMessageText &rhs);
+
+class DraftMessage {
+ public:
+  int32 date;
+  MessageId reply_to_message_id;
+  InputMessageText input_message_text;
+};
+
+using NotificationSettingsScope = int64;
+constexpr NotificationSettingsScope NOTIFICATION_SETTINGS_FOR_PRIVATE_CHATS =
+    std::numeric_limits<NotificationSettingsScope>::min();
+constexpr NotificationSettingsScope NOTIFICATION_SETTINGS_FOR_GROUP_CHATS =
+    std::numeric_limits<NotificationSettingsScope>::min() + 1;
+constexpr NotificationSettingsScope NOTIFICATION_SETTINGS_FOR_ALL_CHATS =
+    std::numeric_limits<NotificationSettingsScope>::min() + 2;
+
+class NotificationSettings {
+ public:
+  int32 mute_until = 0;
+  string sound = "default";
+  bool show_preview = true;
+  bool silent_send_message = false;
+  bool is_synchronized = false;
+
+  NotificationSettings() = default;
+
+  NotificationSettings(int32 mute_until, string sound, bool show_preview, bool silent_send_message)
+      : mute_until(mute_until)
+      , sound(std::move(sound))
+      , show_preview(show_preview)
+      , silent_send_message(silent_send_message)
+      , is_synchronized(true) {
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &string_builder, NotificationSettings notification_settings) {
+  return string_builder << "[" << notification_settings.mute_until << ", " << notification_settings.sound << ", "
+                        << notification_settings.show_preview << ", " << notification_settings.silent_send_message
+                        << ", " << notification_settings.is_synchronized << "]";
+}
+
+inline constexpr size_t search_messages_filter_size() {
+  return static_cast<int32>(SearchMessagesFilter::Size) - 1;
+}
+
+inline int32 search_messages_filter_index(SearchMessagesFilter filter) {
+  CHECK(filter != SearchMessagesFilter::Empty);
+  return static_cast<int32>(filter) - 1;
+}
+
+inline int32 search_messages_filter_index_mask(SearchMessagesFilter filter) {
+  if (filter == SearchMessagesFilter::Empty) {
+    return 0;
+  }
+  return 1 << search_messages_filter_index(filter);
+}
+
+inline int32 search_calls_filter_index(SearchMessagesFilter filter) {
+  CHECK(filter == SearchMessagesFilter::Call || filter == SearchMessagesFilter::MissedCall);
+  return static_cast<int32>(filter) - static_cast<int32>(SearchMessagesFilter::Call);
+}
+
+class DialogDate {
+  int64 order;
+  DialogId dialog_id;
+
+ public:
+  DialogDate(int64 order, DialogId dialog_id) : order(order), dialog_id(dialog_id) {
+  }
+
+  bool operator<(const DialogDate &other) const {
+    return order > other.order || (order == other.order && dialog_id.get() > other.dialog_id.get());
+  }
+
+  bool operator<=(const DialogDate &other) const {
+    return order >= other.order && (order != other.order || dialog_id.get() >= other.dialog_id.get());
+  }
+
+  bool operator==(const DialogDate &other) const {
+    return order == other.order && dialog_id == other.dialog_id;
+  }
+
+  bool operator!=(const DialogDate &other) const {
+    return order != other.order || dialog_id != other.dialog_id;
+  }
+
+  int64 get_order() const {
+    return order;
+  }
+  DialogId get_dialog_id() const {
+    return dialog_id;
+  }
+  int32 get_date() const {
+    return static_cast<int32>((order >> 32) & 0x7FFFFFFF);
+  }
+  MessageId get_message_id() const {
+    return MessageId(ServerMessageId(static_cast<int32>(order & 0x7FFFFFFF)));
+  }
+
+  friend struct DialogDateHash;
+
+  friend StringBuilder &operator<<(StringBuilder &string_builder, DialogDate dialog_date);
+};
+
+const DialogDate MIN_DIALOG_DATE(std::numeric_limits<int64>::max(), DialogId());
+const DialogDate MAX_DIALOG_DATE(0, DialogId());
+const int64 DEFAULT_ORDER = -1;
+
+struct DialogDateHash {
+  std::size_t operator()(const DialogDate &dialog_date) const {
+    return std::hash<int64>()(dialog_date.order) * 2023654985u + DialogIdHash()(dialog_date.dialog_id);
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &string_builder, DialogDate dialog_date) {
+  return string_builder << "[" << dialog_date.order << ", " << dialog_date.dialog_id.get() << "]";
+}
+
+class dummyUpdate : public telegram_api::Update {
+ public:
+  static constexpr int32 ID = 1234567891;
+  int32 get_id() const override {
+    return ID;
+  }
+
+  void store(TlStorerUnsafe &s) const override {
+    UNREACHABLE();
+  }
+
+  void store(TlStorerCalcLength &s) const override {
+    UNREACHABLE();
+  }
+
+  void store(TlStorerToString &s, const char *field_name) const override;
+};
+
+class Dependencies {
+ public:
+  std::unordered_set<UserId, UserIdHash> user_ids;
+  std::unordered_set<ChatId, ChatIdHash> chat_ids;
+  std::unordered_set<ChannelId, ChannelIdHash> channel_ids;
+  std::unordered_set<SecretChatId, SecretChatIdHash> secret_chat_ids;
+  std::unordered_set<DialogId, DialogIdHash> dialog_ids;
+  std::unordered_set<WebPageId, WebPageIdHash> web_page_ids;
+};
+
+struct CallsDbState {
+  std::array<MessageId, 2> first_calls_database_message_id_by_index;
+  std::array<int32, 2> message_count_by_index;
+};
+
+class MessagesManager : public Actor {
+ public:
+  //  static constexpr int32 MESSAGE_FLAG_IS_UNREAD = 1 << 0;
+  static constexpr int32 MESSAGE_FLAG_IS_OUT = 1 << 1;
+  static constexpr int32 MESSAGE_FLAG_IS_FORWARDED = 1 << 2;
+  static constexpr int32 MESSAGE_FLAG_IS_REPLY = 1 << 3;
+  static constexpr int32 MESSAGE_FLAG_HAS_MENTION = 1 << 4;
+  static constexpr int32 MESSAGE_FLAG_HAS_UNREAD_CONTENT = 1 << 5;
+  static constexpr int32 MESSAGE_FLAG_HAS_REPLY_MARKUP = 1 << 6;
+  static constexpr int32 MESSAGE_FLAG_HAS_ENTITIES = 1 << 7;
+  static constexpr int32 MESSAGE_FLAG_HAS_FROM_ID = 1 << 8;
+  static constexpr int32 MESSAGE_FLAG_HAS_MEDIA = 1 << 9;
+  static constexpr int32 MESSAGE_FLAG_HAS_VIEWS = 1 << 10;
+  static constexpr int32 MESSAGE_FLAG_IS_SENT_VIA_BOT = 1 << 11;
+  static constexpr int32 MESSAGE_FLAG_IS_SILENT = 1 << 13;
+  static constexpr int32 MESSAGE_FLAG_IS_POST = 1 << 14;
+  static constexpr int32 MESSAGE_FLAG_HAS_EDIT_DATE = 1 << 15;
+  static constexpr int32 MESSAGE_FLAG_HAS_AUTHOR_SIGNATURE = 1 << 16;
+  static constexpr int32 MESSAGE_FLAG_HAS_MEDIA_ALBUM_ID = 1 << 17;
+
+  static constexpr int32 MESSAGE_FORWARD_HEADER_FLAG_HAS_AUTHOR_ID = 1 << 0;
+  static constexpr int32 MESSAGE_FORWARD_HEADER_FLAG_HAS_CHANNEL_ID = 1 << 1;
+  static constexpr int32 MESSAGE_FORWARD_HEADER_FLAG_HAS_MESSAGE_ID = 1 << 2;
+  static constexpr int32 MESSAGE_FORWARD_HEADER_FLAG_HAS_AUTHOR_SIGNATURE = 1 << 3;
+  static constexpr int32 MESSAGE_FORWARD_HEADER_FLAG_HAS_SAVED_FROM = 1 << 4;
+
+  static constexpr int32 SEND_MESSAGE_FLAG_IS_REPLY = 1 << 0;
+  static constexpr int32 SEND_MESSAGE_FLAG_DISABLE_WEB_PAGE_PREVIEW = 1 << 1;
+  static constexpr int32 SEND_MESSAGE_FLAG_HAS_REPLY_MARKUP = 1 << 2;
+  static constexpr int32 SEND_MESSAGE_FLAG_HAS_ENTITIES = 1 << 3;
+  //  static constexpr int32 SEND_MESSAGE_FLAG_IS_POST = 1 << 4;
+  static constexpr int32 SEND_MESSAGE_FLAG_DISABLE_NOTIFICATION = 1 << 5;
+  static constexpr int32 SEND_MESSAGE_FLAG_FROM_BACKGROUND = 1 << 6;
+  static constexpr int32 SEND_MESSAGE_FLAG_CLEAR_DRAFT = 1 << 7;
+  static constexpr int32 SEND_MESSAGE_FLAG_WITH_MY_SCORE = 1 << 8;
+  static constexpr int32 SEND_MESSAGE_FLAG_GROUP_MEDIA = 1 << 9;
+  static constexpr int32 SEND_MESSAGE_FLAG_HAS_MESSAGE = 1 << 11;
+
+  MessagesManager(Td *td, ActorShared<> parent);
+  MessagesManager(const MessagesManager &) = delete;
+  MessagesManager &operator=(const MessagesManager &) = delete;
+  MessagesManager(MessagesManager &&) = delete;
+  MessagesManager &operator=(MessagesManager &&) = delete;
+  ~MessagesManager() override;
+
+  static vector<MessageId> get_message_ids(const vector<int64> &input_message_ids);
+
+  static vector<int32> get_server_message_ids(const vector<MessageId> &message_ids);
+
+  static tl_object_ptr<telegram_api::InputMessage> get_input_message(MessageId message_id);
+
+  static MessageId get_message_id(const tl_object_ptr<telegram_api::Message> &message_ptr);
+
+  DialogId get_message_dialog_id(const tl_object_ptr<telegram_api::Message> &message_ptr) const;
+
+  FullMessageId get_full_message_id(const tl_object_ptr<telegram_api::Message> &message_ptr) const;
+
+  static int32 get_message_date(const tl_object_ptr<telegram_api::Message> &message_ptr);
+
+  tl_object_ptr<telegram_api::InputPeer> get_input_peer(DialogId dialog_id, AccessRights access_rights) const;
+
+  vector<tl_object_ptr<telegram_api::InputPeer>> get_input_peers(const vector<DialogId> &dialog_ids,
+                                                                 AccessRights access_rights) const;
+
+  tl_object_ptr<telegram_api::inputDialogPeer> get_input_dialog_peer(DialogId dialog_id,
+                                                                     AccessRights access_rights) const;
+
+  vector<tl_object_ptr<telegram_api::inputDialogPeer>> get_input_dialog_peers(const vector<DialogId> &dialog_ids,
+                                                                              AccessRights access_rights) const;
+
+  tl_object_ptr<telegram_api::inputEncryptedChat> get_input_encrypted_chat(DialogId dialog_id,
+                                                                           AccessRights access_rights) const;
+
+  bool have_input_peer(DialogId dialog_id, AccessRights access_rights) const;
+
+  void on_get_messages(vector<tl_object_ptr<telegram_api::Message>> &&messages, bool is_channel_message,
+                       const char *source);
+
+  void on_get_history(DialogId dialog_id, MessageId from_message_id, int32 offset, int32 limit, bool from_the_end,
+                      vector<tl_object_ptr<telegram_api::Message>> &&messages);
+
+  void on_get_public_dialogs_search_result(const string &query, vector<tl_object_ptr<telegram_api::Peer>> &&my_peers,
+                                           vector<tl_object_ptr<telegram_api::Peer>> &&peers);
+  void on_failed_public_dialogs_search(const string &query, Status &&error);
+
+  void on_get_dialog_messages_search_result(DialogId dialog_id, const string &query, UserId sender_user_id,
+                                            MessageId from_message_id, int32 offset, int32 limit,
+                                            SearchMessagesFilter filter, int64 random_id, int32 total_count,
+                                            vector<tl_object_ptr<telegram_api::Message>> &&messages);
+  void on_failed_dialog_messages_search(DialogId dialog_id, int64 random_id);
+
+  void on_get_messages_search_result(const string &query, int32 offset_date, DialogId offset_dialog_id,
+                                     MessageId offset_message_id, int32 limit, int64 random_id, int32 total_count,
+                                     vector<tl_object_ptr<telegram_api::Message>> &&messages);
+  void on_failed_messages_search(int64 random_id);
+
+  void on_get_recent_locations(DialogId dialog_id, int32 limit, int64 random_id, int32 total_count,
+                               vector<tl_object_ptr<telegram_api::Message>> &&messages);
+  void on_get_recent_locations_failed(int64 random_id);
+
+  // if message is from_update, flags have_previous and have_next are ignored and should be both true
+  FullMessageId on_get_message(tl_object_ptr<telegram_api::Message> message_ptr, bool from_update,
+                               bool is_channel_message, bool have_previous, bool have_next, const char *source);
+
+  void open_secret_message(SecretChatId secret_chat_id, int64 random_id, Promise<>);
+
+  void on_send_secret_message_success(int64 random_id, MessageId message_id, int32 date,
+                                      tl_object_ptr<telegram_api::EncryptedFile> file_ptr, Promise<> promise);
+  void on_send_secret_message_error(int64 random_id, Status error, Promise<> promise);
+
+  void delete_secret_messages(SecretChatId secret_chat_id, std::vector<int64> random_ids, Promise<> promise);
+
+  void delete_secret_chat_history(SecretChatId secret_chat_id, MessageId last_message_id, Promise<> promise);
+
+  void read_secret_chat_outbox(SecretChatId secret_chat_id, int32 up_to_date, int32 read_date);
+
+  void on_get_secret_message(SecretChatId secret_chat_id, UserId user_id, MessageId message_id, int32 date,
+                             tl_object_ptr<telegram_api::encryptedFile> file,
+                             tl_object_ptr<secret_api::decryptedMessage> message, Promise<> promise);
+
+  void on_secret_chat_screenshot_taken(SecretChatId secret_chat_id, UserId user_id, MessageId message_id, int32 date,
+                                       int64 random_id, Promise<> promise);
+
+  void on_secret_chat_ttl_changed(SecretChatId secret_chat_id, UserId user_id, MessageId message_id, int32 date,
+                                  int32 ttl, int64 random_id, Promise<> promise);
+
+  void on_update_sent_text_message(int64 random_id, tl_object_ptr<telegram_api::MessageMedia> message_media,
+                                   vector<tl_object_ptr<telegram_api::MessageEntity>> &&entities);
+
+  void on_update_message_web_page(FullMessageId full_message_id, bool have_web_page);
+
+  void on_get_dialogs(vector<tl_object_ptr<telegram_api::dialog>> &&dialogs, int32 total_count,
+                      vector<tl_object_ptr<telegram_api::Message>> &&messages, Promise<Unit> &&promise);
+
+  void on_get_common_dialogs(UserId user_id, vector<tl_object_ptr<telegram_api::Chat>> &&chats, int32 total_count);
+
+  bool on_update_message_id(int64 random_id, MessageId new_message_id, const string &source);
+
+  void on_update_dialog_draft_message(DialogId dialog_id, tl_object_ptr<telegram_api::DraftMessage> &&draft_message);
+
+  void on_update_dialog_pinned(DialogId dialog_id, bool is_pinned);
+
+  void on_update_pinned_dialogs();
+
+  void on_update_service_notification(tl_object_ptr<telegram_api::updateServiceNotification> &&update);
+
+  void on_update_contact_registered(tl_object_ptr<telegram_api::updateContactRegistered> &&update);
+
+  void on_update_new_channel_message(tl_object_ptr<telegram_api::updateNewChannelMessage> &&update);
+
+  void on_update_edit_channel_message(tl_object_ptr<telegram_api::updateEditChannelMessage> &&update);
+
+  void on_update_read_channel_inbox(tl_object_ptr<telegram_api::updateReadChannelInbox> &&update);
+
+  void on_update_read_channel_outbox(tl_object_ptr<telegram_api::updateReadChannelOutbox> &&update);
+
+  void on_update_read_channel_messages_contents(
+      tl_object_ptr<telegram_api::updateChannelReadMessagesContents> &&update);
+
+  void on_update_channel_too_long(tl_object_ptr<telegram_api::updateChannelTooLong> &&update, bool force_apply);
+
+  void on_update_message_views(FullMessageId full_message_id, int32 views);
+
+  void on_read_channel_inbox(ChannelId channel_id, MessageId max_message_id, int32 server_unread_count);
+
+  void on_read_channel_outbox(ChannelId channel_id, MessageId max_message_id);
+
+  void on_update_channel_max_unavailable_message_id(ChannelId channel_id, MessageId max_unavailable_message_id);
+
+  void on_user_dialog_action(DialogId dialog_id, UserId user_id, tl_object_ptr<td_api::ChatAction> &&action,
+                             int32 message_content_id = -1);
+
+  void delete_messages(DialogId dialog_id, const vector<MessageId> &message_ids, bool revoke, Promise<Unit> &&promise);
+
+  void delete_dialog_history(DialogId dialog_id, bool remove_from_dialog_list, Promise<Unit> &&promise);
+
+  void delete_dialog_messages_from_user(DialogId dialog_id, UserId user_id, Promise<Unit> &&promise);
+
+  void delete_dialog(DialogId dialog_id);
+
+  void read_all_dialog_mentions(DialogId dialog_id, Promise<Unit> &&promise);
+
+  Status add_recently_found_dialog(DialogId dialog_id) TD_WARN_UNUSED_RESULT;
+
+  Status remove_recently_found_dialog(DialogId dialog_id) TD_WARN_UNUSED_RESULT;
+
+  void clear_recently_found_dialogs();
+
+  DialogId resolve_dialog_username(const string &username);
+
+  DialogId search_public_dialog(const string &username_to_search, bool force, Promise<Unit> &&promise);
+
+  Result<FormattedText> process_input_caption(DialogId dialog_id, tl_object_ptr<td_api::formattedText> &&text,
+                                              bool is_bot) const;
+
+  Result<InputMessageText> process_input_message_text(
+      DialogId dialog_id, tl_object_ptr<td_api::InputMessageContent> &&input_message_content, bool is_bot,
+      bool for_draft = false) const TD_WARN_UNUSED_RESULT;
+
+  static Result<std::pair<Location, int32>> process_input_message_location(
+      tl_object_ptr<td_api::InputMessageContent> &&input_message_content) TD_WARN_UNUSED_RESULT;
+
+  static Result<Venue> process_input_message_venue(tl_object_ptr<td_api::InputMessageContent> &&input_message_content)
+      TD_WARN_UNUSED_RESULT;
+
+  static Result<Contact> process_input_message_contact(
+      tl_object_ptr<td_api::InputMessageContent> &&input_message_content) TD_WARN_UNUSED_RESULT;
+
+  Result<Game> process_input_message_game(tl_object_ptr<td_api::InputMessageContent> &&input_message_content) const
+      TD_WARN_UNUSED_RESULT;
+
+  bool need_skip_bot_commands(DialogId dialog_id, bool is_bot) const;
+
+  FormattedText get_message_text(string message_text,
+                                 vector<tl_object_ptr<telegram_api::MessageEntity>> &&server_entities,
+                                 int32 send_date) const;
+
+  Result<MessageId> send_message(DialogId dialog_id, MessageId reply_to_message_id, bool disable_notification,
+                                 bool from_background, tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                                 tl_object_ptr<td_api::InputMessageContent> &&input_message_content)
+      TD_WARN_UNUSED_RESULT;
+
+  Result<vector<MessageId>> send_message_group(
+      DialogId dialog_id, MessageId reply_to_message_id, bool disable_notification, bool from_background,
+      vector<tl_object_ptr<td_api::InputMessageContent>> &&input_message_contents) TD_WARN_UNUSED_RESULT;
+
+  Result<MessageId> send_bot_start_message(UserId bot_user_id, DialogId dialog_id,
+                                           const string &parameter) TD_WARN_UNUSED_RESULT;
+
+  Result<MessageId> send_inline_query_result_message(DialogId dialog_id, MessageId reply_to_message_id,
+                                                     bool disable_notification, bool from_background, int64 query_id,
+                                                     const string &result_id) TD_WARN_UNUSED_RESULT;
+
+  Result<vector<MessageId>> forward_messages(DialogId to_dialog_id, DialogId from_dialog_id,
+                                             vector<MessageId> message_ids, bool disable_notification,
+                                             bool from_background, bool in_game_share,
+                                             bool as_album) TD_WARN_UNUSED_RESULT;
+
+  Result<MessageId> send_dialog_set_ttl_message(DialogId dialog_id, int32 ttl);
+
+  Status send_screenshot_taken_notification_message(DialogId dialog_id);
+
+  void edit_message_text(FullMessageId full_message_id, tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                         tl_object_ptr<td_api::InputMessageContent> &&input_message_content, Promise<Unit> &&promise);
+
+  void edit_message_live_location(FullMessageId full_message_id, tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                                  tl_object_ptr<td_api::location> &&input_location, Promise<Unit> &&promise);
+
+  void edit_message_caption(FullMessageId full_message_id, tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                            tl_object_ptr<td_api::formattedText> &&input_caption, Promise<Unit> &&promise);
+
+  void edit_message_reply_markup(FullMessageId full_message_id, tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                                 Promise<Unit> &&promise);
+
+  void edit_inline_message_text(const string &inline_message_id, tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                                tl_object_ptr<td_api::InputMessageContent> &&input_message_content,
+                                Promise<Unit> &&promise);
+
+  void edit_inline_message_live_location(const string &inline_message_id,
+                                         tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                                         tl_object_ptr<td_api::location> &&input_location, Promise<Unit> &&promise);
+
+  void edit_inline_message_caption(const string &inline_message_id, tl_object_ptr<td_api::ReplyMarkup> &&reply_markup,
+                                   tl_object_ptr<td_api::formattedText> &&input_caption, Promise<Unit> &&promise);
+
+  void edit_inline_message_reply_markup(const string &inline_message_id,
+                                        tl_object_ptr<td_api::ReplyMarkup> &&reply_markup, Promise<Unit> &&promise);
+
+  void set_game_score(FullMessageId full_message_id, bool edit_message, UserId user_id, int32 score, bool force,
+                      Promise<Unit> &&promise);
+
+  void set_inline_game_score(const string &inline_message_id, bool edit_message, UserId user_id, int32 score,
+                             bool force, Promise<Unit> &&promise);
+
+  int64 get_game_high_scores(FullMessageId full_message_id, UserId user_id, Promise<Unit> &&promise);
+
+  int64 get_inline_game_high_scores(const string &inline_message_id, UserId user_id, Promise<Unit> &&promise);
+
+  void on_get_game_high_scores(int64 random_id, tl_object_ptr<telegram_api::messages_highScores> &&high_scores);
+
+  tl_object_ptr<td_api::gameHighScores> get_game_high_scores_object(int64 random_id);
+
+  void send_dialog_action(DialogId dialog_id, const tl_object_ptr<td_api::ChatAction> &action, Promise<Unit> &&promise);
+
+  void set_dialog_photo(DialogId dialog_id, const tl_object_ptr<td_api::InputFile> &photo, Promise<Unit> &&promise);
+
+  void set_dialog_title(DialogId dialog_id, const string &title, Promise<Unit> &&promise);
+
+  void add_dialog_participant(DialogId dialog_id, UserId user_id, int32 forward_limit, Promise<Unit> &&promise);
+
+  void add_dialog_participants(DialogId dialog_id, const vector<UserId> &user_ids, Promise<Unit> &&promise);
+
+  void set_dialog_participant_status(DialogId dialog_id, UserId user_id,
+                                     const tl_object_ptr<td_api::ChatMemberStatus> &chat_member_status,
+                                     Promise<Unit> &&promise);
+
+  DialogParticipant get_dialog_participant(DialogId dialog_id, UserId user_id, int64 &random_id, bool force,
+                                           Promise<Unit> &&promise);
+
+  std::pair<int32, vector<DialogParticipant>> search_dialog_participants(DialogId dialog_id, const string &query,
+                                                                         int32 limit, int64 &random_id, bool force,
+                                                                         Promise<Unit> &&promise);
+
+  vector<UserId> get_dialog_administrators(DialogId dialog_id, int left_tries, Promise<Unit> &&promise);
+
+  void export_dialog_invite_link(DialogId dialog_id, Promise<Unit> &&promise);
+
+  string get_dialog_invite_link(DialogId dialog_id);
+
+  int64 get_dialog_event_log(DialogId dialog_id, const string &query, int64 from_event_id, int32 limit,
+                             const tl_object_ptr<td_api::chatEventLogFilters> &filters, const vector<UserId> &user_ids,
+                             Promise<Unit> &&promise);
+
+  void on_get_event_log(int64 random_id, tl_object_ptr<telegram_api::channels_adminLogResults> &&events);
+
+  tl_object_ptr<td_api::chatEvents> get_chat_events_object(int64 random_id);
+
+  bool have_dialog(DialogId dialog_id) const;
+  bool have_dialog_force(DialogId dialog_id);
+
+  bool load_dialog(DialogId dialog_id, int left_tries, Promise<Unit> &&promise);
+
+  void load_dialogs(vector<DialogId> dialog_ids, Promise<Unit> &&promise);
+
+  vector<DialogId> get_dialogs(DialogDate offset, int32 limit, bool force, Promise<Unit> &&promise);
+
+  vector<DialogId> search_public_dialogs(const string &query, Promise<Unit> &&promise);
+
+  std::pair<size_t, vector<DialogId>> search_dialogs(const string &query, int32 limit, Promise<Unit> &&promise);
+
+  vector<DialogId> search_dialogs_on_server(const string &query, int32 limit, Promise<Unit> &&promise);
+
+  vector<DialogId> get_common_dialogs(UserId user_id, DialogId offset_dialog_id, int32 limit, bool force,
+                                      Promise<Unit> &&promise);
+
+  bool have_message(FullMessageId full_message_id);
+
+  void get_message(FullMessageId full_message_id, Promise<Unit> &&promise);
+
+  MessageId get_replied_message(DialogId dialog_id, MessageId message_id, bool force, Promise<Unit> &&promise);
+
+  void get_dialog_pinned_message(DialogId dialog_id, Promise<MessageId> &&promise);
+
+  bool get_messages(DialogId dialog_id, const vector<MessageId> &message_ids, Promise<Unit> &&promise);
+
+  void get_messages_from_server(vector<FullMessageId> &&message_ids, Promise<Unit> &&promise,
+                                tl_object_ptr<telegram_api::InputMessage> input_message = nullptr);
+
+  bool is_message_edited_recently(FullMessageId full_message_id, int32 seconds);
+
+  std::pair<string, string> get_public_message_link(FullMessageId full_message_id, bool for_group,
+                                                    Promise<Unit> &&promise);
+
+  void on_get_public_message_link(FullMessageId full_message_id, bool for_group, string url, string html);
+
+  Status delete_dialog_reply_markup(DialogId dialog_id, MessageId message_id) TD_WARN_UNUSED_RESULT;
+
+  Status set_dialog_draft_message(DialogId dialog_id,
+                                  tl_object_ptr<td_api::draftMessage> &&draft_message) TD_WARN_UNUSED_RESULT;
+
+  Status toggle_dialog_is_pinned(DialogId dialog_id, bool is_pinned) TD_WARN_UNUSED_RESULT;
+
+  Status set_pinned_dialogs(vector<DialogId> dialog_ids) TD_WARN_UNUSED_RESULT;
+
+  Status set_dialog_client_data(DialogId dialog_id, string &&client_data) TD_WARN_UNUSED_RESULT;
+
+  void create_dialog(DialogId dialog_id, bool force, Promise<Unit> &&promise);
+
+  DialogId create_new_group_chat(const vector<UserId> &user_ids, const string &title, int64 &random_id,
+                                 Promise<Unit> &&promise);
+
+  DialogId create_new_channel_chat(const string &title, bool is_megagroup, const string &description, int64 &random_id,
+                                   Promise<Unit> &&promise);
+
+  void create_new_secret_chat(UserId user_id, Promise<SecretChatId> &&promise);
+
+  DialogId migrate_dialog_to_megagroup(DialogId dialog_id, Promise<Unit> &&promise);
+
+  Status open_dialog(DialogId dialog_id) TD_WARN_UNUSED_RESULT;
+
+  Status close_dialog(DialogId dialog_id) TD_WARN_UNUSED_RESULT;
+
+  Status view_messages(DialogId dialog_id, const vector<MessageId> &message_ids, bool force_read) TD_WARN_UNUSED_RESULT;
+
+  Status open_message_content(FullMessageId full_message_id) TD_WARN_UNUSED_RESULT;
+
+  static tl_object_ptr<td_api::NotificationSettingsScope> get_notification_settings_scope_object(
+      NotificationSettingsScope scope);
+
+  static tl_object_ptr<td_api::notificationSettings> get_notification_settings_object(
+      const NotificationSettings *notification_settings);
+
+  const NotificationSettings *get_notification_settings(NotificationSettingsScope scope, Promise<Unit> &&promise);
+
+  Status set_notification_settings(NotificationSettingsScope scope,
+                                   tl_object_ptr<td_api::notificationSettings> &&notification_settings)
+      TD_WARN_UNUSED_RESULT;
+
+  void reset_all_notification_settings();
+
+  tl_object_ptr<td_api::chat> get_chat_object(DialogId dialog_id);
+
+  static tl_object_ptr<td_api::chats> get_chats_object(const vector<DialogId> &dialogs);
+
+  tl_object_ptr<td_api::messages> get_dialog_history(DialogId dialog_id, MessageId from_message_id, int32 offset,
+                                                     int32 limit, int left_tries, bool only_local,
+                                                     Promise<Unit> &&promise);
+
+  std::pair<int32, vector<MessageId>> search_dialog_messages(DialogId dialog_id, const string &query,
+                                                             UserId sender_user_id, MessageId from_message_id,
+                                                             int32 offset, int32 limit,
+                                                             const tl_object_ptr<td_api::SearchMessagesFilter> &filter,
+                                                             int64 &random_id, bool use_db, Promise<Unit> &&promise);
+
+  std::pair<int64, vector<FullMessageId>> offline_search_messages(
+      DialogId dialog_id, const string &query, int64 from_search_id, int32 limit,
+      const tl_object_ptr<td_api::SearchMessagesFilter> &filter, int64 &random_id, Promise<> &&promise);
+
+  std::pair<int32, vector<FullMessageId>> search_messages(const string &query, int32 offset_date,
+                                                          DialogId offset_dialog_id, MessageId offset_message_id,
+                                                          int32 limit, int64 &random_id, Promise<Unit> &&promise);
+
+  std::pair<int32, vector<FullMessageId>> search_call_messages(MessageId from_message_id, int32 limit, bool only_missed,
+                                                               int64 &random_id, bool use_db, Promise<Unit> &&promise);
+
+  std::pair<int32, vector<MessageId>> search_dialog_recent_location_messages(DialogId dialog_id, int32 limit,
+                                                                             int64 &random_id, Promise<Unit> &&promise);
+
+  vector<FullMessageId> get_active_live_location_messages(Promise<Unit> &&promise);
+
+  int64 get_dialog_message_by_date(DialogId dialog_id, int32 date, Promise<Unit> &&promise);
+
+  void on_get_dialog_message_by_date_success(DialogId dialog_id, int32 date, int64 random_id,
+                                             vector<tl_object_ptr<telegram_api::Message>> &&messages);
+
+  void on_get_dialog_message_by_date_fail(int64 random_id);
+
+  tl_object_ptr<td_api::message> get_dialog_message_by_date_object(int64 random_id);
+
+  tl_object_ptr<td_api::message> get_message_object(FullMessageId full_message_id);
+
+  tl_object_ptr<td_api::messages> get_messages_object(int32 total_count, DialogId dialog_id,
+                                                      const vector<MessageId> &message_ids);
+
+  tl_object_ptr<td_api::messages> get_messages_object(int32 total_count, const vector<FullMessageId> &full_message_ids);
+
+  void add_pending_update(tl_object_ptr<telegram_api::Update> &&update, int32 new_pts, int32 pts_count,
+                          bool force_apply, const char *source);
+
+  void add_pending_channel_update(DialogId dialog_id, tl_object_ptr<telegram_api::Update> &&update, int32 new_pts,
+                                  int32 pts_count, const char *source, bool is_postponed_update = false);
+
+  bool is_update_about_username_change_received(DialogId dialog_id) const;
+
+  void on_dialog_photo_updated(DialogId dialog_id);
+  void on_dialog_title_updated(DialogId dialog_id);
+  void on_dialog_username_updated(DialogId dialog_id, const string &old_username, const string &new_username);
+
+  void on_resolved_username(const string &username, DialogId dialog_id);
+  void drop_username(const string &username);
+
+  static tl_object_ptr<telegram_api::MessagesFilter> get_input_messages_filter(SearchMessagesFilter filter);
+
+  static SearchMessagesFilter get_search_messages_filter(const tl_object_ptr<td_api::SearchMessagesFilter> &filter);
+
+  tl_object_ptr<telegram_api::InputNotifyPeer> get_input_notify_peer(NotificationSettingsScope scope) const;
+
+  NotificationSettingsScope get_notification_settings_scope(
+      tl_object_ptr<telegram_api::NotifyPeer> &&notify_peer_ptr) const;
+
+  NotificationSettingsScope get_notification_settings_scope(
+      const tl_object_ptr<td_api::NotificationSettingsScope> &scope) const;
+
+  void on_update_notify_settings(NotificationSettingsScope scope,
+                                 tl_object_ptr<telegram_api::PeerNotifySettings> &&peer_notify_settings);
+
+  bool get_dialog_report_spam_state(DialogId dialog_id, Promise<Unit> &&promise);
+
+  void change_dialog_report_spam_state(DialogId dialog_id, bool is_spam_dialog, Promise<Unit> &&promise);
+
+  void report_dialog(DialogId dialog_id, const tl_object_ptr<td_api::ChatReportReason> &reason,
+                     const vector<MessageId> &message_ids, Promise<Unit> &&promise);
+
+  void on_get_peer_settings(DialogId dialog_id, tl_object_ptr<telegram_api::peerSettings> &&peer_settings);
+
+  void before_get_difference();
+
+  void after_get_difference();
+
+  bool on_get_dialog_error(DialogId dialog_id, const Status &status, const string &source);
+
+  void on_send_message_get_quick_ack(int64 random_id);
+
+  void check_send_message_result(int64 random_id, DialogId dialog_id, const telegram_api::Updates *updates_ptr,
+                                 const char *source);
+
+  FullMessageId on_send_message_success(int64 random_id, MessageId new_message_id, int32 date, FileId new_file_id,
+                                        const char *source);
+
+  void on_send_message_file_part_missing(int64 random_id, int bad_part);
+
+  void on_send_message_fail(int64 random_id, Status error);
+
+  void on_upload_message_media_success(DialogId dialog_id, MessageId message_id,
+                                       tl_object_ptr<telegram_api::MessageMedia> &&media);
+
+  void on_upload_message_media_file_part_missing(DialogId dialog_id, MessageId message_id, int bad_part);
+
+  void on_upload_message_media_fail(DialogId dialog_id, MessageId message_id, Status error);
+
+  void on_create_new_dialog_success(int64 random_id, tl_object_ptr<telegram_api::Updates> &&updates,
+                                    DialogType expected_type, Promise<Unit> &&promise);
+
+  void on_create_new_dialog_fail(int64 random_id, Status error, Promise<Unit> &&promise);
+
+  void on_get_channel_difference(DialogId dialog_id, int32 request_pts, int32 request_limit,
+                                 tl_object_ptr<telegram_api::updates_ChannelDifference> &&difference_ptr);
+
+  void force_create_dialog(DialogId dialog_id, const char *source, bool force_update_dialog_pos = false);
+
+  void on_get_dialog_success(DialogId dialog_id);
+
+  void on_get_dialog_fail(DialogId dialog_id, Status &&error);
+
+  void on_binlog_events(vector<BinlogEvent> &&events);
+
+  void get_payment_form(FullMessageId full_message_id, Promise<tl_object_ptr<td_api::paymentForm>> &&promise);
+
+  void validate_order_info(FullMessageId full_message_id, tl_object_ptr<td_api::orderInfo> order_info, bool allow_save,
+                           Promise<tl_object_ptr<td_api::validatedOrderInfo>> &&promise);
+
+  void send_payment_form(FullMessageId full_message_id, const string &order_info_id, const string &shipping_option_id,
+                         const tl_object_ptr<td_api::InputCredentials> &credentials,
+                         Promise<tl_object_ptr<td_api::paymentResult>> &&promise);
+
+  void get_payment_receipt(FullMessageId full_message_id, Promise<tl_object_ptr<td_api::paymentReceipt>> &&promise);
+
+  ActorOwn<MultiSequenceDispatcher> sequence_dispatcher_;
+
+ private:
+  class PendingPtsUpdate {
+   public:
+    tl_object_ptr<telegram_api::Update> update;
+    int32 pts;
+    int32 pts_count;
+
+    PendingPtsUpdate(tl_object_ptr<telegram_api::Update> &&update, int32 pts, int32 pts_count)
+        : update(std::move(update)), pts(pts), pts_count(pts_count) {
+    }
+  };
+
+  struct MessageInfo {
+    DialogId dialog_id;
+    MessageId message_id;
+    UserId sender_user_id;
+    int32 date;
+    int32 ttl = 0;
+    int64 random_id = 0;
+    tl_object_ptr<telegram_api::messageFwdHeader> forward_header;
+    MessageId reply_to_message_id;
+    UserId via_bot_user_id;
+    int32 views = 0;
+    int32 flags = 0;
+    int32 edit_date = 0;
+    string author_signature;
+    int64 media_album_id = 0;
+
+    unique_ptr<MessageContent> content;
+    tl_object_ptr<telegram_api::ReplyMarkup> reply_markup;
+  };
+
+  struct MessageForwardInfo {
+    UserId sender_user_id;
+    int32 date = 0;
+    DialogId dialog_id;
+    MessageId message_id;
+    string author_signature;
+    DialogId from_dialog_id;
+    MessageId from_message_id;
+
+    MessageForwardInfo() = default;
+
+    MessageForwardInfo(UserId sender_user_id, int32 date, DialogId dialog_id, MessageId message_id,
+                       string author_signature, DialogId from_dialog_id, MessageId from_message_id)
+        : sender_user_id(sender_user_id)
+        , date(date)
+        , dialog_id(dialog_id)
+        , message_id(message_id)
+        , author_signature(std::move(author_signature))
+        , from_dialog_id(from_dialog_id)
+        , from_message_id(from_message_id) {
+    }
+
+    bool operator==(const MessageForwardInfo &rhs) const {
+      return sender_user_id == rhs.sender_user_id && date == rhs.date && dialog_id == rhs.dialog_id &&
+             message_id == rhs.message_id && author_signature == rhs.author_signature &&
+             from_dialog_id == rhs.from_dialog_id && from_message_id == rhs.from_message_id;
+    }
+
+    bool operator!=(const MessageForwardInfo &rhs) const {
+      return !(*this == rhs);
+    }
+
+    friend StringBuilder &operator<<(StringBuilder &string_builder, const MessageForwardInfo &forward_info) {
+      return string_builder << "MessageForwardInfo[sender " << forward_info.sender_user_id << "("
+                            << forward_info.author_signature << "), source " << forward_info.dialog_id << ", source "
+                            << forward_info.message_id << ", from " << forward_info.from_dialog_id << ", from "
+                            << forward_info.from_message_id << " at " << forward_info.date << "]";
+    }
+  };
+
+  // Do not forget to update MessagesManager::update_message when this class is changed
+  struct Message {
+    int32 random_y;
+
+    MessageId message_id;
+    UserId sender_user_id;
+    int32 date = 0;
+    int32 edit_date = 0;
+
+    int64 random_id = 0;
+
+    unique_ptr<MessageForwardInfo> forward_info;
+
+    MessageId reply_to_message_id;
+    int64 reply_to_random_id = 0;  // for send_message
+
+    UserId via_bot_user_id;
+
+    string author_signature;
+
+    bool is_channel_post = false;
+    bool is_outgoing = false;
+    bool is_failed_to_send = false;  // TODO replace with error_code
+    bool disable_notification = false;
+    bool contains_mention = false;
+    bool contains_unread_mention = false;
+    bool had_reply_markup = false;   // had non-inline reply markup?
+    bool is_content_secret = false;  // should be shown only while tapped
+
+    bool from_background = false;           // for send_message
+    bool disable_web_page_preview = false;  // for send_message
+    bool clear_draft = false;               // for send_message
+    bool in_game_share = false;             // for send_message
+
+    bool have_previous = false;
+    bool have_next = false;
+    bool from_database = false;
+
+    int32 views = 0;
+
+    int32 ttl = 0;
+    double ttl_expires_at = 0;
+
+    int64 media_album_id = 0;
+
+    unique_ptr<MessageContent> content;
+
+    unique_ptr<ReplyMarkup> reply_markup;
+
+    unique_ptr<Message> left;
+    unique_ptr<Message> right;
+
+    int32 last_access_date = 0;
+
+    uint64 send_message_logevent_id = 0;
+
+    NetQueryRef send_query_ref;
+
+    DialogId debug_forward_from;
+
+    template <class StorerT>
+    void store(StorerT &storer) const;
+
+    template <class ParserT>
+    void parse(ParserT &parser);
+  };
+
+  struct Dialog {
+    DialogId dialog_id;
+    MessageId last_new_message_id;  // identifier of the last known server message received from update, there should be
+                                    // no server messages after it
+    MessageId last_message_id;      // identifier of the message after which currently there is no any message, i.e. a
+                                    // message without a gap after it, memory only
+    MessageId first_database_message_id;  // identifier of the first message in the database, needed
+                                          // until there is no gaps in the database
+    MessageId last_database_message_id;   // identifier of the last local or server message, if last_database_message_id
+                                          // is known and last_message_id is known then last_database_message_id <=
+                                          // last_message_id
+
+    std::array<MessageId, search_messages_filter_size()> first_database_message_id_by_index;
+    // use struct Count?
+    std::array<int32, search_messages_filter_size()> message_count_by_index;
+
+    int32 server_unread_count = 0;
+    int32 local_unread_count = 0;
+    int32 unread_mention_count = 0;
+    MessageId last_read_inbox_message_id;
+    MessageId last_read_outbox_message_id;
+    MessageId reply_markup_message_id;
+    NotificationSettings notification_settings;
+    unique_ptr<DraftMessage> draft_message;
+    uint64 save_draft_message_logevent_id = 0;
+    uint64 save_draft_message_logevent_id_generation = 0;
+
+    MessageId
+        last_read_all_mentions_message_id;  // all mentions with a message id not greater than it are implicitly read
+    MessageId
+        max_unavailable_message_id;  // maximal unavailable message id for dialogs with cleared/unavailable history
+
+    int32 last_clear_history_date = 0;
+    MessageId last_clear_history_message_id;
+    int64 order = DEFAULT_ORDER;
+    int64 pinned_order = DEFAULT_ORDER;
+    int32 delete_last_message_date = 0;
+    MessageId deleted_last_message_id;
+
+    bool has_contact_registered_message = false;
+
+    bool is_last_message_deleted_locally = false;
+
+    bool know_can_report_spam = false;
+    bool can_report_spam = false;
+
+    bool is_opened = false;
+
+    bool need_restore_reply_markup = true;
+
+    bool have_full_history = false;
+    bool is_empty = false;
+
+    bool is_last_read_inbox_message_id_inited = false;
+    bool is_last_read_outbox_message_id_inited = false;
+
+    bool increment_view_counter = false;
+
+    int32 pts = 0;                                                     // for channels only
+    std::multimap<int32, PendingPtsUpdate> postponed_channel_updates;  // for channels only
+    int32 retry_get_difference_timeout = 1;                            // for channels only
+    std::unordered_map<int64, MessageId> random_id_to_message_id;      // for secret chats only
+
+    MessageId last_assigned_message_id;  // identifier of the last local or yet unsent message, assigned after
+                                         // application start, used to guarantee that all assigned message identifiers
+                                         // are different
+
+    std::unordered_map<MessageId, MessageId, MessageIdHash> yet_unsent_message_id_to_persistent_message_id;
+
+    std::unordered_set<MessageId, MessageIdHash> deleted_message_ids;
+
+    std::vector<MessageId> pending_update_new_messages;
+
+    string client_data;
+
+    // Load from newest to oldest message
+    MessageId suffix_load_first_message_id_;
+    MessageId suffix_load_query_message_id_;
+    std::vector<std::pair<Promise<>, std::function<bool(const Message *)>>> suffix_load_queries_;
+    bool suffix_load_done_ = false;
+    bool suffix_load_has_query_ = false;
+    bool suffix_load_was_query_ = false;
+
+    std::unordered_set<MessageId, MessageIdHash> pending_viewed_message_ids;
+
+    unique_ptr<Message> messages = nullptr;
+
+    struct MessageOp {
+      enum : int8 { Add, SetPts, Delete, DeleteAll } type;
+      bool from_update;
+      bool have_previous;
+      bool have_next;
+      int32 content_type;
+      MessageId message_id;
+      const char *source;
+      double date;
+
+      MessageOp(decltype(type) type, MessageId message_id, int32 content_type, bool from_update, bool have_previous,
+                bool have_next, const char *source)
+          : type(type)
+          , from_update(from_update)
+          , have_previous(have_previous)
+          , have_next(have_next)
+          , content_type(content_type)
+          , message_id(message_id)
+          , source(source)
+          , date(G()->server_time()) {
+      }
+    };
+
+    vector<MessageOp> debug_message_op;
+
+    Dialog() = default;
+    Dialog(const Dialog &) = delete;
+    Dialog &operator=(const Dialog &) = delete;
+    Dialog(Dialog &&other) = delete;
+    Dialog &operator=(Dialog &&other) = delete;
+    ~Dialog();
+
+    template <class StorerT>
+    void store(StorerT &storer) const;
+
+    template <class ParserT>
+    void parse(ParserT &parser);
+  };
+
+  class MessagesIteratorBase {
+    vector<const Message *> stack_;
+
+   protected:
+    MessagesIteratorBase() = default;
+
+    // points iterator to message with greatest id which is less or equal than message_id
+    MessagesIteratorBase(const Message *root, MessageId message_id) {
+      size_t last_right_pos = 0;
+      while (root != nullptr) {
+        //        LOG(DEBUG) << "root->message_id = " << root->message_id;
+        stack_.push_back(root);
+        if (root->message_id.get() <= message_id.get()) {
+          //          LOG(DEBUG) << "Go right";
+          last_right_pos = stack_.size();
+          root = root->right.get();
+        } else {
+          //          LOG(DEBUG) << "Go left";
+          root = root->left.get();
+        }
+      }
+      stack_.resize(last_right_pos);
+    }
+
+    const Message *operator*() const {
+      return stack_.empty() ? nullptr : stack_.back();
+    }
+
+    ~MessagesIteratorBase() = default;
+
+   public:
+    MessagesIteratorBase(const MessagesIteratorBase &) = delete;
+    MessagesIteratorBase &operator=(const MessagesIteratorBase &) = delete;
+    MessagesIteratorBase(MessagesIteratorBase &&other) = default;
+    MessagesIteratorBase &operator=(MessagesIteratorBase &&other) = default;
+
+    void operator++() {
+      if (stack_.empty()) {
+        return;
+      }
+
+      const Message *cur = stack_.back();
+      if (!cur->have_next) {
+        stack_.clear();
+        return;
+      }
+      if (cur->right == nullptr) {
+        while (true) {
+          stack_.pop_back();
+          if (stack_.empty()) {
+            return;
+          }
+          const Message *new_cur = stack_.back();
+          if (new_cur->left.get() == cur) {
+            return;
+          }
+          cur = new_cur;
+        }
+      }
+
+      cur = cur->right.get();
+      while (cur != nullptr) {
+        stack_.push_back(cur);
+        cur = cur->left.get();
+      }
+    }
+
+    void operator--() {
+      if (stack_.empty()) {
+        return;
+      }
+
+      const Message *cur = stack_.back();
+      if (!cur->have_previous) {
+        stack_.clear();
+        return;
+      }
+      if (cur->left == nullptr) {
+        while (true) {
+          stack_.pop_back();
+          if (stack_.empty()) {
+            return;
+          }
+          const Message *new_cur = stack_.back();
+          if (new_cur->right.get() == cur) {
+            return;
+          }
+          cur = new_cur;
+        }
+      }
+
+      cur = cur->left.get();
+      while (cur != nullptr) {
+        stack_.push_back(cur);
+        cur = cur->right.get();
+      }
+    }
+  };
+
+  class MessagesIterator : public MessagesIteratorBase {
+   public:
+    MessagesIterator() = default;
+
+    MessagesIterator(Dialog *d, MessageId message_id) : MessagesIteratorBase(d->messages.get(), message_id) {
+    }
+
+    Message *operator*() const {
+      return const_cast<Message *>(MessagesIteratorBase::operator*());
+    }
+  };
+
+  class MessagesConstIterator : public MessagesIteratorBase {
+   public:
+    MessagesConstIterator() = default;
+
+    MessagesConstIterator(const Dialog *d, MessageId message_id) : MessagesIteratorBase(d->messages.get(), message_id) {
+    }
+
+    const Message *operator*() const {
+      return MessagesIteratorBase::operator*();
+    }
+  };
+
+  struct PendingSecretMessage {
+    MessageInfo message_info;
+    MultiPromiseActor load_data_multipromise;
+    Promise<> success_promise;
+  };
+
+  struct InputMessageContent {
+    unique_ptr<MessageContent> content;
+    bool disable_web_page_preview = false;
+    bool clear_draft = false;
+    int32 ttl = 0;
+    UserId via_bot_user_id;
+
+    InputMessageContent(unique_ptr<MessageContent> &&content, bool disable_web_page_preview, bool clear_draft,
+                        int32 ttl, UserId via_bot_user_id)
+        : content(std::move(content))
+        , disable_web_page_preview(disable_web_page_preview)
+        , clear_draft(clear_draft)
+        , ttl(ttl)
+        , via_bot_user_id(via_bot_user_id) {
+    }
+  };
+
+  class DeleteAllChannelMessagesFromUserOnServerLogEvent;
+  class DeleteDialogHistoryFromServerLogEvent;
+  class DeleteMessageLogEvent;
+  class DeleteMessagesFromServerLogEvent;
+  class ForwardMessagesLogEvent;
+  class GetChannelDifferenceLogEvent;
+  class ReadAllDialogMentionsOnServerLogEvent;
+  class ReadHistoryOnServerLogEvent;
+  class ReadMessageContentsOnServerLogEvent;
+  class ReorderPinnedDialogsOnServerLogEvent;
+  class SaveDialogDraftMessageOnServerLogEvent;
+  class SendBotStartMessageLogEvent;
+  class SendInlineQueryResultMessageLogEvent;
+  class SendMessageLogEvent;
+  class SendScreenshotTakenNotificationMessageLogEvent;
+  class ToggleDialogIsPinnedOnServerLogEvent;
+
+  static constexpr size_t MAX_GROUPED_MESSAGES = 10;               // server side limit
+  static constexpr int32 MAX_GET_DIALOGS = 100;                    // server side limit
+  static constexpr int32 MAX_GET_HISTORY = 100;                    // server side limit
+  static constexpr int32 MAX_SEARCH_MESSAGES = 100;                // server side limit
+  static constexpr int32 MIN_SEARCH_PUBLIC_DIALOG_PREFIX_LEN = 5;  // server side limit
+  static constexpr int32 MIN_CHANNEL_DIFFERENCE = 10;
+  static constexpr int32 MAX_CHANNEL_DIFFERENCE = 100;
+  static constexpr int32 MAX_BOT_CHANNEL_DIFFERENCE = 100000;  // server side limit
+  static constexpr int32 MAX_RECENT_FOUND_DIALOGS = 20;        // some reasonable value
+  static constexpr size_t MAX_CAPTION_LENGTH = 200;            // server side limit
+  static constexpr size_t MAX_NAME_LENGTH = 255;               // server side limit for title and description
+  static constexpr int32 MIN_PINNED_DIALOG_DATE = 2147000000;  // some big date
+  static constexpr int32 MAX_PRIVATE_MESSAGE_TTL = 60;         // server side limit
+
+  static constexpr int32 UPDATE_CHANNEL_TO_LONG_FLAG_HAS_PTS = 1 << 0;
+
+  static constexpr int32 CHANNEL_DIFFERENCE_FLAG_IS_FINAL = 1 << 0;
+  static constexpr int32 CHANNEL_DIFFERENCE_FLAG_HAS_TIMEOUT = 1 << 1;
+
+  static constexpr int32 DIALOG_FLAG_HAS_PTS = 1 << 0;
+  static constexpr int32 DIALOG_FLAG_HAS_DRAFT = 1 << 1;
+  static constexpr int32 DIALOG_FLAG_IS_PINNED = 1 << 2;
+
+  static constexpr int32 MAX_MESSAGE_VIEW_DELAY = 1;  // seconds
+  static constexpr int32 MIN_SAVE_DRAFT_DELAY = 1;    // seconds
+  static constexpr int32 MAX_SAVE_DIALOG_DELAY = 0;   // seconds
+  static constexpr int32 DIALOG_UNLOAD_DELAY = 60;    // seconds
+
+  static constexpr int32 USERNAME_CACHE_EXPIRE_TIME = 3 * 86400;
+  static constexpr int32 USERNAME_CACHE_EXPIRE_TIME_SHORT = 900;
+
+  static constexpr int32 MIN_LIVE_LOCATION_PERIOD = 60;     // seconds, server side limit
+  static constexpr int32 MAX_LIVE_LOCATION_PERIOD = 86400;  // seconds, server side limit
+
+  static constexpr int32 MAX_PRELOADED_DIALOGS = 1000;
+
+  static constexpr double DIALOG_ACTION_TIMEOUT = 5.5;
+
+  static constexpr const char *DELETE_MESSAGE_USER_REQUEST_SOURCE = "user request";
+
+  static constexpr bool DROP_UPDATES = false;
+
+  void open_dialog(Dialog *d);
+
+  void close_dialog(Dialog *d);
+
+  void add_secret_message(unique_ptr<PendingSecretMessage> pending_secret_message, Promise<Unit> lock_promise = Auto());
+
+  void finish_add_secret_message(unique_ptr<PendingSecretMessage> pending_secret_message);
+
+  void fix_message_info_dialog_id(MessageInfo &message_info) const;
+
+  MessageInfo parse_telegram_api_message(tl_object_ptr<telegram_api::Message> message_ptr, const char *source) const;
+
+  std::pair<DialogId, unique_ptr<Message>> create_message(MessageInfo &&message_info, bool is_channel_message);
+
+  FullMessageId on_get_message(MessageInfo &&message_info, bool from_update, bool is_channel_message,
+                               bool have_previous, bool have_next, const char *source);
+
+  Result<InputMessageContent> process_input_message_content(
+      DialogId dialog_id, tl_object_ptr<td_api::InputMessageContent> &&input_message_content) const;
+
+  Message *get_message_to_send(Dialog *d, MessageId reply_to_message_id, bool disable_notification,
+                               bool from_background, unique_ptr<MessageContent> &&content, bool *need_update_dialog_pos,
+                               unique_ptr<MessageForwardInfo> forward_info = nullptr);
+
+  int64 begin_send_message(DialogId dialog_id, const Message *m);
+
+  Status can_send_message(DialogId dialog_id) const TD_WARN_UNUSED_RESULT;
+
+  Status can_send_message_content(DialogId dialog_id, const MessageContent *content,
+                                  bool is_forward) const TD_WARN_UNUSED_RESULT;
+
+  bool can_edit_message(DialogId dialog_id, const Message *m, bool is_editing, bool only_reply_markup = false) const;
+
+  bool can_report_dialog(DialogId dialog_id) const;
+
+  MessageId get_persistent_message_id(const Dialog *d, MessageId message_id) const;
+
+  static MessageId get_replied_message_id(const Message *m);
+
+  MessageId get_reply_to_message_id(Dialog *d, MessageId message_id);
+
+  bool can_set_game_score(DialogId dialog_id, const Message *m) const;
+
+  bool check_update_dialog_id(const tl_object_ptr<telegram_api::Update> &update, DialogId dialog_id);
+
+  void process_update(tl_object_ptr<telegram_api::Update> &&update);
+
+  void process_channel_update(tl_object_ptr<telegram_api::Update> &&update);
+
+  void delete_messages_from_updates(const vector<MessageId> &message_ids);
+
+  void delete_dialog_messages_from_updates(DialogId dialog_id, const vector<MessageId> &message_ids);
+
+  void do_forward_messages(DialogId to_dialog_id, DialogId from_dialog_id, const vector<Message *> &messages,
+                           const vector<MessageId> &message_ids, int64 logevent_id);
+
+  Result<MessageId> forward_message(DialogId to_dialog_id, DialogId from_dialog_id, MessageId message_id,
+                                    bool disable_notification, bool from_background,
+                                    bool in_game_share) TD_WARN_UNUSED_RESULT;
+
+  SecretInputMedia get_secret_input_media(const MessageContent *content,
+                                          tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                          BufferSlice thumbnail, int32 layer);
+
+  tl_object_ptr<telegram_api::invoice> get_input_invoice(const Invoice &invoice) const;
+
+  tl_object_ptr<telegram_api::inputWebDocument> get_input_web_document(const Photo &photo) const;
+
+  tl_object_ptr<telegram_api::inputMediaInvoice> get_input_media_invoice(const MessageInvoice *message_invoice) const;
+
+  tl_object_ptr<telegram_api::InputMedia> get_input_media(const MessageContent *content,
+                                                          tl_object_ptr<telegram_api::InputFile> input_file,
+                                                          tl_object_ptr<telegram_api::InputFile> input_thumbnail,
+                                                          int32 ttl);
+
+  void delete_message_content_thumbnail(MessageContent *content);
+
+  void do_send_media(DialogId dialog_id, Message *m, FileId file_id, FileId thumbnail_file_id,
+                     tl_object_ptr<telegram_api::InputFile> input_file,
+                     tl_object_ptr<telegram_api::InputFile> input_thumbnail);
+
+  void do_send_secret_media(DialogId dialog_id, Message *m, FileId file_id, FileId thumbnail_file_id,
+                            tl_object_ptr<telegram_api::InputEncryptedFile> input_encrypted_file,
+                            BufferSlice thumbnail);
+
+  void do_send_message(DialogId dialog_id, Message *m, vector<int> bad_parts = {});
+
+  void on_message_media_uploaded(DialogId dialog_id, Message *m, tl_object_ptr<telegram_api::InputMedia> &&input_media,
+                                 FileId file_id, FileId thumbnail_file_id);
+
+  void on_secret_message_media_uploaded(DialogId dialog_id, Message *m, SecretInputMedia &&secret_input_media,
+                                        FileId file_id, FileId thumbnail_file_id);
+
+  void on_upload_message_media_finished(int64 media_album_id, DialogId dialog_id, MessageId message_id, Status result);
+
+  void do_send_message_group(int64 media_album_id);
+
+  void on_media_message_ready_to_send(DialogId dialog_id, MessageId message_id, Promise<Message *> &&promise);
+
+  void on_yet_unsent_media_queue_updated(DialogId dialog_id);
+
+  void save_send_bot_start_message_logevent(UserId bot_user_id, DialogId dialog_id, const string &parameter,
+                                            Message *m);
+
+  void do_send_bot_start_message(UserId bot_user_id, DialogId dialog_id, const string &parameter, Message *m);
+
+  void save_send_inline_query_result_message_logevent(DialogId dialog_id, Message *m, int64 query_id,
+                                                      const string &result_id);
+
+  void do_send_inline_query_result_message(DialogId dialog_id, Message *m, int64 query_id, const string &result_id);
+
+  uint64 save_send_screenshot_taken_notification_message_logevent(DialogId dialog_id, const Message *m);
+
+  void do_send_screenshot_taken_notification_message(DialogId dialog_id, const Message *m, uint64 logevent_id);
+
+  Message *continue_send_message(DialogId dialog_id, unique_ptr<Message> &&m, uint64 logevent_id);
+
+  tl_object_ptr<telegram_api::InputChatPhoto> get_input_chat_photo(FileId file_id) const;
+
+  bool is_message_unload_enabled() const;
+
+  static bool is_allowed_media_group_content(int32 content_type);
+
+  static bool can_forward_message(DialogId from_dialog_id, const Message *m);
+
+  static bool is_secret_message_content(int32 ttl, int32 content_type);
+
+  static bool is_service_message_content(int32 content_type);
+
+  static bool can_have_message_content_caption(int32 content_type);
+
+  static bool can_delete_channel_message(DialogParticipantStatus status, const Message *m, bool is_bot);
+
+  bool can_revoke_message(DialogId dialog_id, const Message *m) const;
+
+  bool can_unload_message(const Dialog *d, const Message *m) const;
+
+  void unload_message(Dialog *d, MessageId message_id);
+
+  unique_ptr<Message> delete_message(Dialog *d, MessageId message_id, bool is_permanently_deleted,
+                                     bool *need_update_dialog_pos, const char *source);
+
+  unique_ptr<Message> do_delete_message(Dialog *d, MessageId message_id, bool is_permanently_deleted,
+                                        bool only_from_memory, bool *need_update_dialog_pos, const char *source);
+
+  void unload_dialog(DialogId dialog_id);
+
+  void delete_all_dialog_messages(Dialog *d, bool remove_from_dialog_list, bool is_permanent);
+
+  void do_delete_all_dialog_messages(Dialog *d, unique_ptr<Message> &m, vector<int64> &deleted_message_ids);
+
+  void delete_messages_from_server(DialogId dialog_id, vector<MessageId> message_ids, bool revoke, uint64 logevent_id,
+                                   Promise<Unit> &&promise);
+
+  void delete_dialog_history_from_server(DialogId dialog_id, MessageId max_message_id, bool remove_from_dialog_list,
+                                         bool allow_error, uint64 logevent_id, Promise<Unit> &&promise);
+
+  void delete_all_channel_messages_from_user_on_server(ChannelId channel_id, UserId user_id, uint64 logevent_id,
+                                                       Promise<Unit> &&promise);
+
+  void read_all_dialog_mentions_on_server(DialogId dialog_id, uint64 logevent_id, Promise<Unit> &&promise);
+
+  static MessageId find_message_by_date(const unique_ptr<Message> &m, int32 date);
+
+  static void find_messages_from_user(const unique_ptr<Message> &m, UserId user_id, vector<MessageId> &message_ids);
+
+  static void find_unread_mentions(const unique_ptr<Message> &m, vector<MessageId> &message_ids);
+
+  static void find_old_messages(const unique_ptr<Message> &m, MessageId max_message_id, vector<MessageId> &message_ids);
+
+  void find_unloadable_messages(const Dialog *d, int32 unload_before_date, const unique_ptr<Message> &m,
+                                vector<MessageId> &message_ids, int32 &left_to_unload) const;
+
+  bool update_message_views(DialogId dialog_id, Message *m, int32 views);
+
+  bool update_message_contains_unread_mention(Dialog *d, Message *m, bool contains_unread_mention, const char *source);
+
+  static bool update_opened_message_content(Message *m);
+
+  void read_message_content_from_updates(MessageId message_id);
+
+  void read_channel_message_content_from_updates(Dialog *d, MessageId message_id);
+
+  bool read_message_content(Dialog *d, Message *m, bool is_local_read, const char *source);
+
+  void read_message_contents_on_server(DialogId dialog_id, vector<MessageId> message_ids, uint64 logevent_id);
+
+  void read_history_inbox(DialogId dialog_id, MessageId max_message_id, int32 unread_count, const char *source);
+
+  void read_history_outbox(DialogId dialog_id, MessageId max_message_id, int32 read_date = -1);
+
+  void read_history_on_server(DialogId dialog_id, MessageId max_message_id, bool allow_error, uint64 logevent_id);
+
+  void read_secret_chat_outbox_inner(DialogId dialog_id, int32 up_to_date, int32 read_date);
+
+  void set_dialog_max_unavailable_message_id(DialogId dialog_id, MessageId max_unavailable_message_id, bool from_update,
+                                             const char *source);
+
+  void preload_newer_messages(const Dialog *d, MessageId max_message_id);
+
+  void preload_older_messages(const Dialog *d, MessageId min_message_id);
+
+  void on_get_history_from_database(DialogId dialog_id, MessageId from_message_id, int32 offset, int32 limit,
+                                    bool from_the_end, bool only_local, vector<BufferSlice> &&messages,
+                                    Promise<Unit> &&promise);
+
+  void get_history_from_the_end(DialogId dialog_id, bool from_database, bool only_local, Promise<Unit> &&promise);
+
+  void get_history(DialogId dialog_id, MessageId from_message_id, int32 offset, int32 limit, bool from_database,
+                   bool only_local, Promise<Unit> &&promise);
+
+  void load_messages(DialogId dialog_id, MessageId from_message_id, int32 offset, int32 limit, int left_tries,
+                     bool only_local, Promise<Unit> &&promise);
+
+  static int32 get_random_y(MessageId message_id);
+
+  bool is_allowed_useless_update(const tl_object_ptr<telegram_api::Update> &update) const;
+
+  bool is_message_auto_read(DialogId dialog_id, bool is_outgoing, bool only_content) const;
+
+  void fail_send_message(FullMessageId full_message_id, int error_code, const string &error_message);
+
+  void on_dialog_updated(DialogId dialog_id, const char *source);
+
+  BufferSlice get_dialog_database_value(const Dialog *d);
+
+  void save_dialog_to_database(DialogId dialog_id);
+
+  void on_save_dialog_to_database(DialogId dialog_id, bool success);
+
+  void load_dialog_list(Promise<Unit> &&promise);
+
+  void load_dialog_list_from_database(int32 limit, Promise<Unit> &&promise);
+
+  static void preload_dialog_list(void *messages_manager_void);
+
+  void update_message_count_by_index(Dialog *d, int diff, const Message *m);
+
+  int32 get_message_index_mask(DialogId dialog_id, const Message *m) const;
+
+  int32 get_message_content_index_mask(const MessageContent *content, bool is_secret, bool is_outgoing) const;
+
+  Message *add_message_to_dialog(DialogId dialog_id, unique_ptr<Message> message, bool from_update, bool *need_update,
+                                 bool *need_update_dialog_pos, const char *source);
+
+  Message *add_message_to_dialog(Dialog *d, unique_ptr<Message> message, bool from_update, bool *need_update,
+                                 bool *need_update_dialog_pos, const char *source);
+
+  void on_message_changed(const Dialog *d, const Message *m, const char *source);
+
+  void add_message_to_database(const Dialog *d, const Message *m, const char *source);
+
+  void delete_all_dialog_messages_from_database(DialogId dialog_id, MessageId message_id, const char *source);
+
+  void delete_message_from_database(Dialog *d, MessageId message_id, const Message *m,
+                                    bool is_permanently_deleted) const;
+
+  void delete_message_files(const Message *m) const;
+
+  void do_delete_message_logevent(const DeleteMessageLogEvent &logevent) const;
+
+  void attach_message_to_previous(Dialog *d, MessageId message_id);
+
+  void attach_message_to_next(Dialog *d, MessageId message_id);
+
+  void update_message(Dialog *d, unique_ptr<Message> &old_message, unique_ptr<Message> new_message,
+                      bool need_send_update_message_content, bool *need_update_dialog_pos);
+
+  bool need_message_text_changed_warning(const Message *old_message, const MessageText *old_content,
+                                         const MessageText *new_content);
+
+  bool update_message_content(DialogId dialog_id, Message *old_message, unique_ptr<MessageContent> &old_content,
+                              unique_ptr<MessageContent> new_content, bool need_send_update_message_content);
+
+  void send_update_new_message(Dialog *d, const Message *m, bool force = false);
+
+  void flush_pending_update_new_messages(DialogId dialog_id);
+
+  void send_update_message_send_succeeded(Dialog *d, MessageId old_message_id, const Message *m) const;
+
+  void send_update_message_content(DialogId dialog_id, MessageId message_id, const MessageContent *content,
+                                   int32 message_date, bool is_content_secret, const char *source) const;
+
+  void send_update_message_edited(FullMessageId full_message_id);
+
+  void send_update_message_edited(DialogId dialog_id, const Message *m);
+
+  void send_update_delete_messages(DialogId dialog_id, vector<int64> &&message_ids, bool is_permanent,
+                                   bool from_cache) const;
+
+  void send_update_chat(Dialog *d);
+
+  void send_update_chat_draft_message(const Dialog *d);
+
+  void send_update_chat_last_message(Dialog *d, const char *source);
+
+  void send_update_chat_last_message_impl(const Dialog *d, const char *source) const;
+
+  void send_update_unread_message_count(DialogId dialog_id, bool force, const char *source);
+
+  void send_update_chat_read_inbox(const Dialog *d, bool force, const char *source);
+
+  void send_update_chat_read_outbox(const Dialog *d);
+
+  void send_update_chat_unread_mention_count(const Dialog *d);
+
+  tl_object_ptr<td_api::message> get_message_object(DialogId dialog_id, const Message *message) const;
+
+  static tl_object_ptr<td_api::messages> get_messages_object(int32 total_count,
+                                                             vector<tl_object_ptr<td_api::message>> &&messages);
+
+  vector<DialogId> sort_dialogs_by_order(const vector<DialogId> &dialog_ids, int32 limit) const;
+
+  vector<DialogId> get_peers_dialog_ids(vector<tl_object_ptr<telegram_api::Peer>> &&peers);
+
+  void recalc_unread_message_count();
+
+  void set_dialog_last_read_inbox_message_id(Dialog *d, MessageId message_id, int32 server_unread_count,
+                                             int32 local_unread_count, bool force_update, const char *source);
+
+  void set_dialog_last_read_outbox_message_id(Dialog *d, MessageId message_id);
+
+  void set_dialog_last_message_id(Dialog *d, MessageId last_message_id, const char *source);
+
+  void set_dialog_first_database_message_id(Dialog *d, MessageId first_database_message_id, const char *source);
+
+  void set_dialog_last_database_message_id(Dialog *d, MessageId last_database_message_id, const char *source);
+
+  void set_dialog_last_new_message_id(Dialog *d, MessageId last_new_message_id, const char *source);
+
+  void set_dialog_last_clear_history_date(Dialog *d, int32 date, MessageId last_clear_history_message_id,
+                                          const char *source);
+
+  void set_dialog_is_empty(Dialog *d, const char *source);
+
+  static int32 get_pinned_dialogs_limit();
+
+  static vector<DialogId> remove_secret_chat_dialog_ids(vector<DialogId> dialog_ids);
+
+  void set_dialog_is_pinned(DialogId dialog_id, bool is_pinned);
+
+  void set_dialog_is_pinned(Dialog *d, bool is_pinned);
+
+  void toggle_dialog_is_pinned_on_server(DialogId dialog_id, bool is_pinned, uint64 logevent_id);
+
+  void reorder_pinned_dialogs_on_server(const vector<DialogId> &dialog_ids, uint64 logevent_id);
+
+  void set_dialog_reply_markup(Dialog *d, MessageId message_id);
+
+  void try_restore_dialog_reply_markup(Dialog *d, const Message *m);
+
+  static string get_notification_settings_scope_database_key(NotificationSettingsScope scope);
+
+  bool update_notification_settings(NotificationSettingsScope scope, NotificationSettings *current_settings,
+                                    const NotificationSettings &new_settings);
+
+  void update_dialog_unmute_timeout(Dialog *d, int32 old_mute_until, int32 new_mute_until);
+
+  void on_dialog_unmute(DialogId dialog_id);
+
+  void on_send_dialog_action_timeout(DialogId dialog_id);
+
+  void on_active_dialog_action_timeout(DialogId dialog_id);
+
+  static bool need_cancel_user_dialog_action(int32 action_id, int32 message_content_id);
+
+  void cancel_user_dialog_action(DialogId dialog_id, const Message *m);
+
+  Dialog *get_dialog_by_message_id(MessageId message_id);
+
+  MessageId get_message_id_by_random_id(Dialog *d, int64 random_id);
+
+  Dialog *add_dialog(DialogId dialog_id);
+
+  Dialog *add_new_dialog(unique_ptr<Dialog> &&d, bool is_loaded_from_database);
+
+  void fix_new_dialog(Dialog *d, unique_ptr<Message> &&last_database_message, int64 order,
+                      int32 last_clear_history_date, MessageId last_clear_history_message_id);
+
+  void add_dialog_last_database_message(Dialog *d, unique_ptr<Message> &&last_database_message);
+
+  tl_object_ptr<td_api::inputMessageText> get_input_message_text_object(
+      const InputMessageText &input_message_text) const;
+
+  tl_object_ptr<td_api::draftMessage> get_draft_message_object(const unique_ptr<DraftMessage> &draft_message) const;
+
+  tl_object_ptr<td_api::ChatType> get_chat_type_object(DialogId dialog_id) const;
+
+  tl_object_ptr<td_api::chat> get_chat_object(const Dialog *d);
+
+  bool have_dialog_info(DialogId dialog_id) const;
+  bool have_dialog_info_force(DialogId dialog_id) const;
+
+  Dialog *get_dialog(DialogId dialog_id);
+  const Dialog *get_dialog(DialogId dialog_id) const;
+
+  Dialog *get_dialog_force(DialogId dialog_id);
+
+  Dialog *on_load_dialog_from_database(const Result<BufferSlice> &r_value);
+
+  void on_get_dialogs_from_database(vector<BufferSlice> &&dialogs, Promise<Unit> &&promise);
+
+  void send_get_dialog_query(DialogId dialog_id, Promise<Unit> &&promise);
+
+  void send_search_public_dialogs_query(const string &query, Promise<Unit> &&promise);
+
+  vector<DialogId> get_pinned_dialogs() const;
+
+  void update_dialogs_hints(const Dialog *d);
+  void update_dialogs_hints_rating(const Dialog *d);
+
+  std::pair<int32, vector<DialogParticipant>> search_private_chat_participants(UserId my_user_id, UserId peer_user_id,
+                                                                               const string &query, int32 limit) const;
+
+  static unique_ptr<Message> *find_message(unique_ptr<Message> *v, MessageId message_id);
+  static const unique_ptr<Message> *find_message(const unique_ptr<Message> *v, MessageId message_id);
+
+  static Message *get_message(Dialog *d, MessageId message_id);
+  static const Message *get_message(const Dialog *d, MessageId message_id);
+
+  Message *get_message(FullMessageId full_message_id);
+  const Message *get_message(FullMessageId full_message_id) const;
+
+  Message *get_message_force(Dialog *d, MessageId message_id);
+
+  Message *get_message_force(FullMessageId full_message_id);
+
+  void get_message_force_from_server(Dialog *d, MessageId message_id, Promise<Unit> &&promise,
+                                     tl_object_ptr<telegram_api::InputMessage> input_message = nullptr);
+
+  Message *on_get_message_from_database(DialogId dialog_id, Dialog *d, const BufferSlice &value);
+
+  void get_dialog_message_by_date_from_server(const Dialog *d, int32 date, int64 random_id, bool after_database_search,
+                                              Promise<Unit> &&promise);
+
+  void on_get_dialog_message_by_date_from_database(DialogId dialog_id, int32 date, int64 random_id,
+                                                   Result<BufferSlice> result, Promise<Unit> promise);
+
+  static NotificationSettings get_notification_settings(
+      tl_object_ptr<telegram_api::PeerNotifySettings> &&notification_settings);
+
+  const NotificationSettings *get_dialog_notification_settings(const Dialog *d, DialogId dialog_id) const;
+
+  NotificationSettings *get_notification_settings(NotificationSettingsScope scope, bool force);
+
+  static unique_ptr<DraftMessage> get_draft_message(ContactsManager *contacts_manager,
+                                                    tl_object_ptr<telegram_api::DraftMessage> &&draft_message_ptr);
+
+  static FormattedText get_secret_media_caption(string &&message_text, string &&message_caption);
+
+  Photo get_web_document_photo(tl_object_ptr<telegram_api::WebDocument> web_document, DialogId owner_dialog_id) const;
+
+  unique_ptr<MessageContent> get_secret_message_document(
+      tl_object_ptr<telegram_api::encryptedFile> file,
+      tl_object_ptr<secret_api::decryptedMessageMediaDocument> &&document,
+      vector<tl_object_ptr<telegram_api::DocumentAttribute>> &&attributes, DialogId owner_dialog_id,
+      FormattedText &&caption, bool is_opened) const;
+
+  unique_ptr<MessageContent> get_message_document(tl_object_ptr<telegram_api::document> &&document,
+                                                  DialogId owner_dialog_id, FormattedText &&caption, bool is_opened,
+                                                  MultiPromiseActor *load_data_multipromise_ptr) const;
+
+  unique_ptr<MessageContent> get_message_document(std::pair<DocumentsManager::DocumentType, FileId> &&parsed_document,
+                                                  FormattedText &&caption, bool is_opened) const;
+
+  unique_ptr<MessagePhoto> get_message_photo(tl_object_ptr<telegram_api::photo> &&photo, DialogId owner_dialog_id,
+                                             FormattedText &&caption) const;
+
+  unique_ptr<MessageContent> get_secret_message_content(
+      string message_text, tl_object_ptr<telegram_api::encryptedFile> file,
+      tl_object_ptr<secret_api::DecryptedMessageMedia> &&media,
+      vector<tl_object_ptr<secret_api::MessageEntity>> &&secret_entities, DialogId owner_dialog_id,
+      MultiPromiseActor &load_data_multipromise) const;
+
+  unique_ptr<MessageContent> get_message_content(FormattedText message_text,
+                                                 tl_object_ptr<telegram_api::MessageMedia> &&media,
+                                                 DialogId owner_dialog_id, bool is_content_read, UserId via_bot_user_id,
+                                                 int32 *ttl) const;
+
+  unique_ptr<MessageContent> dup_message_content(DialogId dialog_id, const MessageContent *content, bool for_forward);
+
+  unique_ptr<MessageContent> get_message_action_content(tl_object_ptr<telegram_api::MessageAction> &&action,
+                                                        DialogId owner_dialog_id, MessageId reply_to_message_id) const;
+
+  tl_object_ptr<td_api::MessageContent> get_message_content_object(const MessageContent *content, int32 message_date,
+                                                                   bool is_content_secret) const;
+
+  static FormattedText get_message_content_caption(const MessageContent *content);
+
+  int32 get_message_content_duration(const MessageContent *content) const;
+
+  static FileId get_message_content_file_id(const MessageContent *content);
+
+  static void update_message_content_file_id_remote(MessageContent *content, FileId file_id);
+
+  FileId get_message_content_thumbnail_file_id(const MessageContent *content) const;
+
+  vector<FileId> get_message_file_ids(const Message *message) const;
+
+  void cancel_send_message_query(DialogId dialog_id, unique_ptr<Message> &m);
+
+  static int32 get_message_flags(const Message *m);
+
+  unique_ptr<MessageForwardInfo> get_message_forward_info(
+      tl_object_ptr<telegram_api::messageFwdHeader> &&forward_header);
+
+  tl_object_ptr<td_api::MessageForwardInfo> get_message_forward_info_object(
+      const unique_ptr<MessageForwardInfo> &forward_info) const;
+
+  void ttl_read_history_inbox(DialogId dialog_id, MessageId from_message_id, MessageId till_message_id,
+                              double timestamp);
+  void ttl_read_history_outbox(DialogId dialog_id, MessageId from_message_id, MessageId till_message_id,
+                               double timestamp);
+  void ttl_on_view(const Dialog *d, Message *message, double view_date, double now);
+  bool ttl_on_open(Dialog *d, Message *message, double now, bool is_local_read);
+  void ttl_register_message(DialogId dialog_id, const Message *message, double now);
+  void ttl_unregister_message(DialogId dialog_id, const Message *message, double now);
+  void ttl_loop(double now);
+  void ttl_update_timeout(double now);
+
+  void on_message_ttl_expired(Dialog *d, Message *message);
+  void on_message_ttl_expired_impl(Dialog *d, Message *message);
+
+  void start_up() override;
+  void loop() override;
+  void tear_down() override;
+
+  void ttl_db_loop_start(double server_now);
+  void ttl_db_loop(double server_now);
+  void ttl_db_on_result(Result<std::pair<std::vector<std::pair<DialogId, BufferSlice>>, int32>> r_result, bool dummy);
+
+  static MessageId get_first_database_message_id_by_index(const Dialog *d, SearchMessagesFilter filter);
+
+  void on_search_dialog_messages_db_result(int64 random_id, DialogId dialog_id, MessageId from_message_id,
+                                           MessageId first_db_message_id, SearchMessagesFilter filter_type,
+                                           int32 offset, int32 limit, Result<MessagesDbMessagesResult> result,
+                                           Promise<> promise);
+
+  void on_messages_db_fts_result(Result<MessagesDbFtsResult> result, int64 random_id, Promise<> &&promise);
+
+  void on_messages_db_calls_result(Result<MessagesDbCallsResult> result, int64 random_id, MessageId first_db_message_id,
+                                   SearchMessagesFilter filter, Promise<> &&promise);
+
+  void on_load_active_live_location_full_message_ids_from_database(string value);
+
+  void on_load_active_live_location_messages_finished();
+
+  void try_add_active_live_location(DialogId dialog_id, const Message *m);
+
+  void add_active_live_location(FullMessageId full_message_id);
+
+  bool delete_active_live_location(DialogId dialog_id, const Message *m);
+
+  void save_active_live_locations();
+
+  Result<unique_ptr<ReplyMarkup>> get_dialog_reply_markup(
+      DialogId dialog_id, tl_object_ptr<td_api::ReplyMarkup> &&reply_markup_ptr) const TD_WARN_UNUSED_RESULT;
+
+  const DialogPhoto *get_dialog_photo(DialogId dialog_id) const;
+
+  string get_dialog_title(DialogId dialog_id) const;
+
+  string get_dialog_username(DialogId dialog_id) const;
+
+  static int64 get_dialog_order(MessageId message_id, int32 message_date);
+
+  bool update_dialog_draft_message(Dialog *d, unique_ptr<DraftMessage> &&draft_message, bool from_update,
+                                   bool need_update_dialog_pos);
+
+  void save_dialog_draft_message_on_server(DialogId dialog_id);
+
+  void on_saved_dialog_draft_message(DialogId dialog_id, uint64 generation);
+
+  int64 get_next_pinned_dialog_order();
+
+  void update_dialog_pos(Dialog *d, bool remove_from_dialog_list, const char *source,
+                         bool need_send_update_chat_order = true);
+
+  bool set_dialog_order(Dialog *d, int64 new_order, bool need_send_update_chat_order);
+
+  void update_last_dialog_date();
+
+  void load_notification_settings();
+
+  void set_get_difference_timeout(double timeout);
+
+  void skip_old_pending_update(tl_object_ptr<telegram_api::Update> &&update, int32 new_pts, int32 old_pts,
+                               int32 pts_count, const char *source);
+
+  void process_pending_updates();
+
+  void drop_pending_updates();
+
+  static string get_channel_pts_key(DialogId dialog_id);
+
+  int32 load_channel_pts(DialogId dialog_id) const;
+
+  void set_channel_pts(Dialog *d, int32 new_pts, const char *source) const;
+
+  bool running_get_channel_difference(DialogId dialog_id) const;
+
+  void get_channel_difference(DialogId dialog_id, int32 pts, bool force, const char *source);
+
+  void do_get_channel_difference(DialogId dialog_id, int32 pts, bool force,
+                                 tl_object_ptr<telegram_api::InputChannel> &&input_channel, const char *source);
+
+  void process_get_channel_difference_updates(DialogId dialog_id,
+                                              vector<tl_object_ptr<telegram_api::Message>> &&new_messages,
+                                              vector<tl_object_ptr<telegram_api::Update>> &&other_updates);
+
+  void on_get_channel_dialog(DialogId dialog_id, MessageId last_message_id, MessageId read_inbox_max_message_id,
+                             int32 server_unread_count, int32 unread_mention_count,
+                             MessageId read_outbox_max_message_id,
+                             vector<tl_object_ptr<telegram_api::Message>> &&messages);
+
+  void after_get_channel_difference(DialogId dialog_id, bool success);
+
+  static void on_channel_get_difference_timeout_callback(void *messages_manager_ptr, int64 dialog_id_int);
+
+  static void on_pending_message_views_timeout_callback(void *messages_manager_ptr, int64 dialog_id_int);
+
+  static void on_pending_draft_message_timeout_callback(void *messages_manager_ptr, int64 dialog_id_int);
+
+  static void on_pending_updated_dialog_timeout_callback(void *messages_manager_ptr, int64 dialog_id_int);
+
+  static void on_pending_unload_dialog_timeout_callback(void *messages_manager_ptr, int64 dialog_id_int);
+
+  static void on_dialog_unmute_timeout_callback(void *messages_manager_ptr, int64 dialog_id_int);
+
+  static void on_pending_send_dialog_action_timeout_callback(void *messages_manager_ptr, int64 dialog_id_int);
+
+  static void on_active_dialog_action_timeout_callback(void *messages_manager_ptr, int64 dialog_id_int);
+
+  void load_secret_thumbnail(FileId thumbnail_file_id);
+
+  static tl_object_ptr<telegram_api::channelAdminLogEventsFilter> get_channel_admin_log_events_filter(
+      const tl_object_ptr<td_api::chatEventLogFilters> &filters);
+
+  tl_object_ptr<td_api::ChatEventAction> get_chat_event_action_object(
+      tl_object_ptr<telegram_api::ChannelAdminLogEventAction> &&action_ptr);
+
+  void on_upload_media(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file,
+                       tl_object_ptr<telegram_api::InputEncryptedFile> input_encrypted_file);
+  void on_upload_media_error(FileId file_id, Status status);
+
+  void on_load_secret_thumbnail(FileId thumbnail_file_id, BufferSlice thumbnail);
+  void on_upload_thumbnail(FileId thumbnail_file_id, tl_object_ptr<telegram_api::InputFile> thumbnail_input_file);
+
+  void on_upload_dialog_photo(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file);
+  void on_upload_dialog_photo_error(FileId file_id, Status status);
+
+  static uint64 get_sequence_dispatcher_id(DialogId dialog_id, int32 message_content_type);
+
+  Dialog *get_service_notifications_dialog();
+
+  static MessageId get_next_message_id(Dialog *d, int32 type);
+
+  static MessageId get_next_local_message_id(Dialog *d);
+
+  static MessageId get_next_yet_unsent_message_id(Dialog *d);
+
+  bool add_recently_found_dialog_internal(DialogId dialog_id);
+
+  bool remove_recently_found_dialog_internal(DialogId dialog_id);
+
+  void save_recently_found_dialogs();
+  bool load_recently_found_dialogs(Promise<Unit> &promise);
+
+  void update_used_hashtags(DialogId dialog_id, const Message *m);
+
+  string get_search_text(const Message *m);
+
+  unique_ptr<Dialog> parse_dialog(DialogId dialog_id, const BufferSlice &value);
+
+  void load_calls_db_state();
+  void save_calls_db_state();
+
+  static constexpr bool is_debug_message_op_enabled();
+
+  static void dump_debug_message_op(const Dialog *d, int priority = 0);
+
+  void add_message_dependencies(Dependencies &dependencies, DialogId dialog_id, const Message *m);
+
+  void add_dialog_dependencies(Dependencies &dependencies, DialogId dialog_id);
+
+  void resolve_dependencies_force(const Dependencies &dependencies);
+
+  void save_send_message_logevent(DialogId dialog_id, Message *m);
+
+  void suffix_load_loop(Dialog *d);
+  void suffix_load_update_first_message_id(Dialog *d);
+  void suffix_load_query_ready(DialogId dialog_id);
+  void suffix_load_add_query(Dialog *d, std::pair<Promise<>, std::function<bool(const Message *)>> query);
+  void suffix_load_till_date(Dialog *d, int32 date, Promise<> promise);
+  void suffix_load_till_message_id(Dialog *d, MessageId message_id, Promise<> promise);
+
+  Result<ServerMessageId> get_invoice_message_id(FullMessageId full_message_id);
+
+  bool is_broadcast_channel(DialogId dialog_id) const;
+
+  int32 recently_found_dialogs_loaded_ = 0;  // 0 - not loaded, 1 - load request was sent, 2 - loaded
+  MultiPromiseActor resolve_recent_found_dialogs_multipromise_;
+
+  vector<DialogId> recently_found_dialog_ids_;
+
+  class UploadMediaCallback;
+  class UploadThumbnailCallback;
+  class UploadDialogPhotoCallback;
+
+  std::shared_ptr<UploadMediaCallback> upload_media_callback_;
+  std::shared_ptr<UploadThumbnailCallback> upload_thumbnail_callback_;
+  std::shared_ptr<UploadDialogPhotoCallback> upload_dialog_photo_callback_;
+
+  int32 accumulated_pts_count_ = 0;
+  int32 accumulated_pts_ = -1;
+  Timeout pts_gap_timeout_;
+
+  std::unordered_map<FileId, std::pair<FullMessageId, FileId>, FileIdHash>
+      being_uploaded_files_;  // file_id -> message, thumbnail_file_id
+  struct UploadedThumbnailInfo {
+    FullMessageId full_message_id;
+    FileId file_id;                                     // original file file_id
+    tl_object_ptr<telegram_api::InputFile> input_file;  // original file InputFile
+  };
+  std::unordered_map<FileId, UploadedThumbnailInfo, FileIdHash> being_uploaded_thumbnails_;  // thumbnail_file_id -> ...
+  struct UploadedSecretThumbnailInfo {
+    FullMessageId full_message_id;
+    FileId file_id;                                              // original file file_id
+    tl_object_ptr<telegram_api::InputEncryptedFile> input_file;  // original file InputEncryptedFile
+  };
+  std::unordered_map<FileId, UploadedSecretThumbnailInfo, FileIdHash>
+      being_loaded_secret_thumbnails_;  // thumbnail_file_id -> ...
+
+  // TTL
+  class TtlNode : private HeapNode {
+   public:
+    TtlNode(DialogId dialog_id, MessageId message_id) : full_message_id(dialog_id, message_id) {
+    }
+
+    FullMessageId full_message_id;
+
+    HeapNode *as_heap_node() const {
+      return const_cast<HeapNode *>(static_cast<const HeapNode *>(this));
+    }
+    static TtlNode *from_heap_node(HeapNode *node) {
+      return static_cast<TtlNode *>(node);
+    }
+
+    bool operator==(const TtlNode &other) const {
+      return full_message_id == other.full_message_id;
+    }
+  };
+  struct TtlNodeHash {
+    std::size_t operator()(const TtlNode &ttl_node) const {
+      return FullMessageIdHash()(ttl_node.full_message_id);
+    }
+  };
+  std::unordered_set<TtlNode, TtlNodeHash> ttl_nodes_;
+  KHeap<double> ttl_heap_;
+  Slot ttl_slot_;
+
+  enum YieldType { None, Ttl, TtlDb };  // None must be first
+  int32 ttl_db_expire_from_;
+  int32 ttl_db_expire_till_;
+  bool ttl_db_has_query_;
+  Slot ttl_db_slot_;
+
+  std::unordered_set<int64> message_random_ids_;
+  std::unordered_map<int64, FullMessageId> being_sent_messages_;  // message_random_id -> message
+
+  std::unordered_map<FullMessageId, MessageId, FullMessageIdHash>
+      update_message_ids_;                                         // full_message_id -> temporary_id
+  std::unordered_map<int64, DialogId> debug_being_sent_messages_;  // message_random_id -> dialog_id
+
+  const char *debug_add_message_to_dialog_fail_reason = "";
+
+  struct UploadedDialogPhotoInfo {
+    Promise<Unit> promise;
+    DialogId dialog_id;
+  };
+  std::unordered_map<FileId, UploadedDialogPhotoInfo, FileIdHash> uploaded_dialog_photos_;  // file_id -> ...
+
+  struct PendingMessageGroupSend {
+    DialogId dialog_id;
+    size_t finished_count = 0;
+    vector<MessageId> message_ids;
+    vector<bool> is_finished;
+    vector<Status> results;
+  };
+  std::unordered_map<int64, PendingMessageGroupSend> pending_message_group_sends_;  // media_album_id -> ...
+
+  std::unordered_map<MessageId, DialogId, MessageIdHash> message_id_to_dialog_id_;
+  std::unordered_map<MessageId, DialogId, MessageIdHash> last_clear_history_message_id_to_dialog_id_;
+
+  std::unordered_map<int64, DialogId> created_dialogs_;                                // random_id -> dialog_id
+  std::unordered_map<DialogId, Promise<Unit>, DialogIdHash> pending_created_dialogs_;  // dialog_id -> promise
+
+  bool running_get_difference_ = false;  // true after before_get_difference and false after after_get_difference
+
+  std::unordered_map<DialogId, unique_ptr<Dialog>, DialogIdHash> dialogs_;
+  std::multimap<int32, PendingPtsUpdate> pending_updates_;
+  std::multimap<int32, PendingPtsUpdate> postponed_pts_updates_;
+
+  std::unordered_set<DialogId, DialogIdHash>
+      loaded_dialogs_;  // dialogs loaded from database, but not added to dialogs_
+
+  std::unordered_set<DialogId, DialogIdHash> postponed_chat_read_inbox_updates_;
+  std::unordered_map<DialogId, vector<std::pair<MessageId, Promise<Unit>>>, DialogIdHash>
+      postponed_get_message_requests_;
+
+  std::unordered_map<string, vector<Promise<Unit>>> search_public_dialogs_queries_;
+  std::unordered_map<string, vector<DialogId>> found_public_dialogs_;     // TODO time bound cache
+  std::unordered_map<string, vector<DialogId>> found_on_server_dialogs_;  // TODO time bound cache
+
+  std::unordered_map<UserId, vector<DialogId>, UserIdHash> found_common_dialogs_;  // TODO time bound cache
+
+  std::unordered_map<int64, FullMessageId> get_dialog_message_by_date_results_;
+
+  std::unordered_map<int64, std::pair<int32, vector<MessageId>>>
+      found_dialog_messages_;  // random_id -> [total_count, [message_id]...]
+  std::unordered_map<int64, std::pair<int32, vector<FullMessageId>>>
+      found_messages_;  // random_id -> [total_count, [full_message_id]...]
+  std::unordered_map<int64, std::pair<int32, vector<FullMessageId>>>
+      found_call_messages_;  // random_id -> [total_count, [full_message_id]...]
+  std::unordered_map<int64, std::pair<int32, vector<MessageId>>>
+      found_dialog_recent_location_messages_;  // random_id -> [total_count, [message_id]...]
+
+  std::unordered_map<int64, std::pair<int64, vector<FullMessageId>>>
+      found_fts_messages_;  // random_id -> [from_search_id, [full_message_id]...]
+
+  std::unordered_map<FullMessageId, std::pair<string, string>, FullMessageIdHash> public_message_links_[2];
+
+  std::unordered_map<int64, tl_object_ptr<td_api::chatEvents>> chat_events_;  // random_id -> chat events
+
+  std::unordered_map<int64, tl_object_ptr<td_api::gameHighScores>> game_high_scores_;  // random_id -> high scores
+
+  std::unordered_map<DialogId, vector<Promise<Unit>>, DialogIdHash> get_dialog_queries_;
+
+  std::unordered_map<FullMessageId, int32, FullMessageIdHash> replied_by_yet_unsent_messages_;
+
+  std::unordered_set<FullMessageId, FullMessageIdHash> waiting_for_web_page_messages_;
+
+  struct ActiveDialogAction {
+    UserId user_id;
+    int32 action_id;
+    int32 progress;
+    double start_time;
+
+    ActiveDialogAction(UserId user_id, int32 action_id, double start_time)
+        : user_id(user_id), action_id(action_id), start_time(start_time) {
+    }
+  };
+
+  std::unordered_map<DialogId, std::vector<ActiveDialogAction>, DialogIdHash> active_dialog_actions_;
+
+  NotificationSettings users_notification_settings_;
+  NotificationSettings chats_notification_settings_;
+  NotificationSettings dialogs_notification_settings_;
+
+  bool have_postponed_unread_message_count_update_ = false;
+  bool is_unread_count_inited_ = false;
+  bool need_unread_count_recalc_ = true;
+  int32 unread_message_total_count_ = 0;
+  int32 unread_message_muted_count_ = 0;
+
+  // uint32 preloaded_dialogs_ = 0;  // TODO remove variable
+
+  int64 current_pinned_dialog_order_ = DEFAULT_ORDER;
+
+  std::set<DialogDate> ordered_dialogs_;
+  std::set<DialogDate> ordered_server_dialogs_;
+
+  // date of last dialog in the dialog list
+  // last_dialog_date_ == min(last_server_dialog_date_, last_secret_chat_dialog_date_)
+  DialogDate last_dialog_date_ = MIN_DIALOG_DATE;  // in memory
+
+  // date of last known user/group/channel dialog in the right order
+  DialogDate last_server_dialog_date_ = MIN_DIALOG_DATE;
+  DialogDate last_loaded_database_dialog_date_ = MIN_DIALOG_DATE;
+  DialogDate last_database_server_dialog_date_ = MIN_DIALOG_DATE;
+
+  MultiPromiseActor load_dialog_list_multipromise_;  // should be defined before pending_on_get_dialogs_
+  Timeout preload_dialog_list_timeout_;
+
+  std::unordered_map<DialogId, string, DialogIdHash> active_get_channel_differencies_;
+  std::unordered_map<DialogId, uint64, DialogIdHash> get_channel_difference_to_logevent_id_;
+
+  MultiTimeout channel_get_difference_timeout_;
+  MultiTimeout channel_get_difference_retry_timeout_;
+  MultiTimeout pending_message_views_timeout_;
+  MultiTimeout pending_draft_message_timeout_;
+  MultiTimeout pending_updated_dialog_timeout_;
+  MultiTimeout pending_unload_dialog_timeout_;
+  MultiTimeout dialog_unmute_timeout_;
+  MultiTimeout pending_send_dialog_action_timeout_;
+  MultiTimeout active_dialog_action_timeout_;
+
+  Hints dialogs_hints_;  // search dialogs by title and username
+
+  std::unordered_set<FullMessageId, FullMessageIdHash> active_live_location_full_message_ids_;
+  bool are_active_live_location_messages_loaded_ = false;
+  vector<Promise<Unit>> load_active_live_location_messages_queries_;
+
+  struct ResolvedUsername {
+    DialogId dialog_id;
+    double expires_at;
+  };
+
+  std::unordered_map<string, ResolvedUsername> resolved_usernames_;
+  std::unordered_map<string, DialogId> unaccessible_resolved_usernames_;
+
+  struct PendingOnGetDialogs {
+    vector<tl_object_ptr<telegram_api::dialog>> dialogs;
+    int32 total_count;
+    vector<tl_object_ptr<telegram_api::Message>> messages;
+    Promise<Unit> promise;
+  };
+
+  vector<PendingOnGetDialogs> pending_on_get_dialogs_;
+  std::unordered_map<DialogId, PendingOnGetDialogs, DialogIdHash> pending_channel_on_get_dialogs_;
+
+  ChangesProcessor<unique_ptr<PendingSecretMessage>> pending_secret_messages_;
+
+  std::unordered_map<DialogId, vector<DialogId>, DialogIdHash>
+      pending_add_dialog_last_database_message_dependent_dialogs_;
+  std::unordered_map<DialogId, std::pair<int32, unique_ptr<Message>>, DialogIdHash>
+      pending_add_dialog_last_database_message_;  // dialog -> dependency counter + message
+
+  CallsDbState calls_db_state_;
+
+  std::unordered_map<uint64, std::map<int64, Promise<Message *>>> yet_unsent_media_queues_;
+
+  std::unordered_map<DialogId, NetQueryRef, DialogIdHash> set_typing_query_;
+
+  Td *td_;
+  ActorShared<> parent_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/PasswordManager.cpp b/libs/tdlib/td/td/telegram/PasswordManager.cpp
new file mode 100644
index 0000000000..7fbff2ba0e
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/PasswordManager.cpp
@@ -0,0 +1,330 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/PasswordManager.h"
+
+#include "td/telegram/Global.h"
+#include "td/telegram/logevent/LogEvent.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/crypto.h"
+#include "td/utils/logging.h"
+#include "td/utils/Random.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"  // TODO: this file is already included. Why?
+
+namespace td {
+
+tl_object_ptr<td_api::temporaryPasswordState> TempPasswordState::as_td_api() const {
+  if (!has_temp_password || valid_until <= G()->unix_time()) {
+    return make_tl_object<td_api::temporaryPasswordState>(false, 0);
+  }
+  return make_tl_object<td_api::temporaryPasswordState>(true, valid_until - G()->unix_time_cached());
+}
+
+static BufferSlice calc_password_hash(const string &password, const string &salt) {
+  if (password.empty()) {
+    return BufferSlice();
+  }
+  BufferSlice buf(32);
+  string salted_password = salt + password + salt;
+  sha256(salted_password, buf.as_slice());
+  return buf;
+}
+
+void PasswordManager::set_password(string current_password, string new_password, string new_hint,
+                                   bool set_recovery_email_address, string recovery_email_address,
+                                   Promise<State> promise) {
+  UpdateSettings update_settings;
+
+  update_settings.current_password = std::move(current_password);
+  update_settings.update_password = true;
+  update_settings.new_password = std::move(new_password);
+  update_settings.new_hint = std::move(new_hint);
+
+  if (set_recovery_email_address) {
+    update_settings.update_recovery_email_address = true;
+    update_settings.recovery_email_address = std::move(recovery_email_address);
+  }
+
+  update_password_settings(std::move(update_settings), std::move(promise));
+}
+void PasswordManager::set_recovery_email_address(string password, string new_recovery_email_address,
+                                                 Promise<State> promise) {
+  UpdateSettings update_settings;
+  update_settings.current_password = std::move(password);
+  update_settings.update_recovery_email_address = true;
+  update_settings.recovery_email_address = std::move(new_recovery_email_address);
+
+  update_password_settings(std::move(update_settings), std::move(promise));
+}
+
+void PasswordManager::get_temp_password_state(Promise<TempState> promise) /*const*/ {
+  promise.set_value(temp_password_state_.as_td_api());
+}
+
+TempPasswordState PasswordManager::get_temp_password_state_sync() {
+  auto temp_password_str = G()->td_db()->get_binlog_pmc()->get("temp_password");
+  TempPasswordState res;
+  auto status = log_event_parse(res, temp_password_str);
+  if (status.is_error() || res.valid_until <= G()->unix_time()) {
+    res = TempPasswordState();
+  }
+  return res;
+}
+
+void PasswordManager::create_temp_password(string password, int32 timeout, Promise<TempState> promise) {
+  if (create_temp_password_promise_) {
+    return promise.set_error(Status::Error(400, "Another create_temp_password query is active"));
+  }
+  create_temp_password_promise_ = std::move(promise);
+
+  auto new_promise = PromiseCreator::lambda([actor_id = actor_id(this)](Result<TempPasswordState> result) {
+    send_closure(actor_id, &PasswordManager::on_finish_create_temp_password, std::move(result), false);
+  });
+
+  do_get_state(PromiseCreator::lambda([password = std::move(password), timeout, promise = std::move(new_promise),
+                                       actor_id = actor_id(this)](Result<PasswordState> r_state) mutable {
+    if (r_state.is_error()) {
+      return promise.set_error(r_state.move_as_error());
+    }
+    send_closure(actor_id, &PasswordManager::do_create_temp_password, std::move(password), timeout,
+                 r_state.move_as_ok(), std::move(promise));
+  }));
+}
+
+void PasswordManager::drop_temp_password() {
+  G()->td_db()->get_binlog_pmc()->erase("temp_password");
+  temp_password_state_ = TempPasswordState();
+}
+
+void PasswordManager::do_create_temp_password(string password, int32 timeout, PasswordState &&password_state,
+                                              Promise<TempPasswordState> promise) {
+  send_with_promise(G()->net_query_creator().create(create_storer(telegram_api::account_getTmpPassword(
+                        calc_password_hash(password, password_state.current_salt), timeout))),
+                    PromiseCreator::lambda([promise = std::move(promise)](Result<NetQueryPtr> r_query) mutable {
+                      if (r_query.is_error()) {
+                        return promise.set_error(r_query.move_as_error());
+                      }
+                      auto r_result = fetch_result<telegram_api::account_getTmpPassword>(r_query.move_as_ok());
+                      if (r_result.is_error()) {
+                        return promise.set_error(r_result.move_as_error());
+                      }
+                      auto result = r_result.move_as_ok();
+                      TempPasswordState res;
+                      res.has_temp_password = true;
+                      res.temp_password = result->tmp_password_.as_slice().str();
+                      res.valid_until = result->valid_until_;
+                      promise.set_value(std::move(res));
+                    }));
+}
+
+void PasswordManager::on_finish_create_temp_password(Result<TempPasswordState> result, bool /*dummy*/) {
+  CHECK(create_temp_password_promise_);
+  if (result.is_error()) {
+    drop_temp_password();
+    return create_temp_password_promise_.set_error(result.move_as_error());
+  }
+  temp_password_state_ = result.move_as_ok();
+  G()->td_db()->get_binlog_pmc()->set("temp_password", log_event_store(temp_password_state_).as_slice().str());
+  create_temp_password_promise_.set_value(temp_password_state_.as_td_api());
+}
+
+void PasswordManager::get_recovery_email_address(string password,
+                                                 Promise<tl_object_ptr<td_api::recoveryEmailAddress>> promise) {
+  do_get_state(PromiseCreator::lambda([password = std::move(password), promise = std::move(promise),
+                                       actor_id = actor_id(this)](Result<PasswordState> r_state) mutable {
+    if (r_state.is_error()) {
+      return promise.set_error(r_state.move_as_error());
+    }
+    send_closure(actor_id, &PasswordManager::do_get_recovery_email_address, std::move(password), r_state.move_as_ok(),
+                 std::move(promise));
+  }));
+}
+
+void PasswordManager::request_password_recovery(Promise<tl_object_ptr<td_api::passwordRecoveryInfo>> promise) {
+  send_with_promise(G()->net_query_creator().create(create_storer(telegram_api::auth_requestPasswordRecovery())),
+                    PromiseCreator::lambda([promise = std::move(promise)](Result<NetQueryPtr> r_query) mutable {
+                      if (r_query.is_error()) {
+                        return promise.set_error(r_query.move_as_error());
+                      }
+                      auto r_result = fetch_result<telegram_api::auth_requestPasswordRecovery>(r_query.move_as_ok());
+                      if (r_result.is_error()) {
+                        return promise.set_error(r_result.move_as_error());
+                      }
+                      auto result = r_result.move_as_ok();
+                      return promise.set_value(make_tl_object<td_api::passwordRecoveryInfo>(result->email_pattern_));
+                    }));
+}
+
+void PasswordManager::recover_password(string code, Promise<State> promise) {
+  send_with_promise(G()->net_query_creator().create(create_storer(telegram_api::auth_recoverPassword(std::move(code)))),
+                    PromiseCreator::lambda(
+                        [actor_id = actor_id(this), promise = std::move(promise)](Result<NetQueryPtr> r_query) mutable {
+                          if (r_query.is_error()) {
+                            return promise.set_error(r_query.move_as_error());
+                          }
+                          auto r_result = fetch_result<telegram_api::auth_recoverPassword>(r_query.move_as_ok());
+                          if (r_result.is_error()) {
+                            return promise.set_error(r_result.move_as_error());
+                          }
+                          send_closure(actor_id, &PasswordManager::get_state, std::move(promise));
+                        }));
+}
+
+void PasswordManager::do_get_recovery_email_address(string password, PasswordState state,
+                                                    Promise<tl_object_ptr<td_api::recoveryEmailAddress>> promise) {
+  send_with_promise(G()->net_query_creator().create(create_storer(
+                        telegram_api::account_getPasswordSettings(calc_password_hash(password, state.current_salt)))),
+                    PromiseCreator::lambda([promise = std::move(promise)](Result<NetQueryPtr> r_query) mutable {
+                      if (r_query.is_error()) {
+                        return promise.set_error(r_query.move_as_error());
+                      }
+                      auto r_result = fetch_result<telegram_api::account_getPasswordSettings>(r_query.move_as_ok());
+                      if (r_result.is_error()) {
+                        return promise.set_error(r_result.move_as_error());
+                      }
+                      auto result = r_result.move_as_ok();
+                      return promise.set_value(make_tl_object<td_api::recoveryEmailAddress>(result->email_));
+                    }));
+}
+
+void PasswordManager::update_password_settings(UpdateSettings update_settings, Promise<State> promise) {
+  auto result_promise = PromiseCreator::lambda(
+      [actor_id = actor_id(this), promise = std::move(promise)](Result<bool> r_update_settings) mutable {
+        if (r_update_settings.is_error()) {
+          promise.set_error(r_update_settings.move_as_error());
+          return;
+        }
+        if (!r_update_settings.ok()) {
+          promise.set_error(Status::Error(5, "account_updatePasswordSettings returned false"));
+          return;
+        }
+        send_closure(actor_id, &PasswordManager::get_state, std::move(promise));
+      });
+
+  do_get_state(
+      PromiseCreator::lambda([=, actor_id = actor_id(this), result_promise = std::move(result_promise),
+                              update_settings = std::move(update_settings)](Result<PasswordState> r_state) mutable {
+        if (r_state.is_error()) {
+          result_promise.set_error(r_state.move_as_error());
+          return;
+        }
+        send_closure(actor_id, &PasswordManager::do_update_password_settings, std::move(update_settings),
+                     r_state.move_as_ok(), std::move(result_promise));
+      }));
+}
+
+void PasswordManager::do_update_password_settings(UpdateSettings update_settings, PasswordState state,
+                                                  Promise<bool> promise) {
+  auto new_settings = make_tl_object<telegram_api::account_passwordInputSettings>();
+  if (update_settings.update_password) {
+    new_settings->flags_ |= telegram_api::account_passwordInputSettings::NEW_PASSWORD_HASH_MASK;
+    new_settings->flags_ |= telegram_api::account_passwordInputSettings::NEW_SALT_MASK;
+    new_settings->flags_ |= telegram_api::account_passwordInputSettings::HINT_MASK;
+    if (!update_settings.new_password.empty()) {
+      BufferSlice new_salt(state.new_salt.size() * 2);
+      new_salt.as_slice().copy_from(state.new_salt);
+      Random::secure_bytes(new_salt.as_slice().remove_prefix(state.new_salt.size()));
+
+      new_settings->new_salt_ = std::move(new_salt);
+      new_settings->new_password_hash_ =
+          calc_password_hash(update_settings.new_password, new_settings->new_salt_.as_slice().str());
+      new_settings->hint_ = std::move(update_settings.new_hint);
+    }
+  }
+  if (update_settings.update_recovery_email_address) {
+    new_settings->flags_ |= telegram_api::account_passwordInputSettings::EMAIL_MASK;
+    new_settings->email_ = std::move(update_settings.recovery_email_address);
+  }
+  BufferSlice current_hash;
+  if (state.has_password) {
+    current_hash = calc_password_hash(update_settings.current_password, state.current_salt);
+  }
+  auto query = G()->net_query_creator().create(
+      create_storer(telegram_api::account_updatePasswordSettings(std::move(current_hash), std::move(new_settings))));
+
+  send_with_promise(std::move(query), PromiseCreator::lambda([actor_id = actor_id(this), promise = std::move(promise)](
+                                                                 Result<NetQueryPtr> r_query) mutable {
+                      if (r_query.is_error()) {
+                        return promise.set_error(r_query.move_as_error());
+                      }
+                      auto r_result = fetch_result<telegram_api::account_updatePasswordSettings>(r_query.move_as_ok());
+                      if (r_result.is_error()) {
+                        if (r_result.error().code() == 400 && r_result.error().message() == "EMAIL_UNCONFIRMED") {
+                          return promise.set_value(true);
+                        }
+                        return promise.set_error(r_result.move_as_error());
+                      }
+                      return promise.set_value(r_result.move_as_ok());
+                    }));
+}
+
+void PasswordManager::get_state(Promise<State> promise) {
+  do_get_state(PromiseCreator::lambda([promise = std::move(promise)](Result<PasswordState> r_state) mutable {
+    if (r_state.is_error()) {
+      promise.set_error(r_state.move_as_error());
+      return;
+    }
+    promise.set_value(r_state.move_as_ok().as_td_api());
+  }));
+}
+
+void PasswordManager::do_get_state(Promise<PasswordState> promise) {
+  auto query = G()->net_query_creator().create(create_storer(telegram_api::account_getPassword()));
+  send_with_promise(std::move(query), PromiseCreator::lambda([actor_id = actor_id(this), promise = std::move(promise)](
+                                                                 Result<NetQueryPtr> r_query) mutable {
+                      if (r_query.is_error()) {
+                        promise.set_error(r_query.move_as_error());
+                        return;
+                      }
+                      auto r_result = fetch_result<telegram_api::account_getPassword>(r_query.move_as_ok());
+                      if (r_result.is_error()) {
+                        promise.set_error(r_result.move_as_error());
+                        return;
+                      }
+                      auto result = r_result.move_as_ok();
+
+                      PasswordState state;
+                      if (result->get_id() == telegram_api::account_noPassword::ID) {
+                        auto no_password = move_tl_object_as<telegram_api::account_noPassword>(result);
+                        state.has_password = false;
+                        state.password_hint = "";
+                        state.current_salt = "";
+                        state.new_salt = no_password->new_salt_.as_slice().str();
+                        state.has_recovery_email_address = false;
+                        state.unconfirmed_recovery_email_address_pattern = no_password->email_unconfirmed_pattern_;
+                      } else if (result->get_id() == telegram_api::account_password::ID) {
+                        auto password = move_tl_object_as<telegram_api::account_password>(result);
+                        state.has_password = true;
+                        state.password_hint = password->hint_;
+                        state.current_salt = password->current_salt_.as_slice().str();
+                        state.new_salt = password->new_salt_.as_slice().str();
+                        state.has_recovery_email_address = password->has_recovery_;
+                        state.unconfirmed_recovery_email_address_pattern = password->email_unconfirmed_pattern_;
+                      } else {
+                        UNREACHABLE();
+                      }
+                      promise.set_value(std::move(state));
+                    }));
+}
+
+void PasswordManager::on_result(NetQueryPtr query) {
+  auto token = get_link_token();
+  container_.extract(token).set_value(std::move(query));
+}
+void PasswordManager::send_with_promise(NetQueryPtr query, Promise<NetQueryPtr> promise) {
+  auto id = container_.create(std::move(promise));
+  G()->net_query_dispatcher().dispatch_with_callback(std::move(query), actor_shared(this, id));
+}
+
+void PasswordManager::start_up() {
+  temp_password_state_ = get_temp_password_state_sync();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/PasswordManager.h b/libs/tdlib/td/td/telegram/PasswordManager.h
new file mode 100644
index 0000000000..fb67d46f6e
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/PasswordManager.h
@@ -0,0 +1,116 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/utils/Container.h"
+#include "td/utils/logging.h"
+#include "td/utils/Status.h"
+#include "td/utils/tl_helpers.h"
+
+#include "td/telegram/td_api.h"
+
+namespace td {
+
+struct TempPasswordState {
+  bool has_temp_password = false;
+  string temp_password;
+  int32 valid_until = 0;  // unix_time
+
+  tl_object_ptr<td_api::temporaryPasswordState> as_td_api() const;
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    CHECK(has_temp_password);
+    store(temp_password, storer);
+    store(valid_until, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    has_temp_password = true;
+    parse(temp_password, parser);
+    parse(valid_until, parser);
+  }
+};
+
+class PasswordManager : public NetQueryCallback {
+ public:
+  using State = tl_object_ptr<td_api::passwordState>;
+  using TempState = tl_object_ptr<td_api::temporaryPasswordState>;
+
+  explicit PasswordManager(ActorShared<> parent) : parent_(std::move(parent)) {
+  }
+  void get_state(Promise<State> promise);
+  void set_password(string current_password, string new_password, string new_hint, bool set_recovery_email_address,
+                    string recovery_email_address, Promise<State> promise);
+  void set_recovery_email_address(string password, string new_recovery_email_address, Promise<State> promise);
+  void get_recovery_email_address(string password, Promise<tl_object_ptr<td_api::recoveryEmailAddress>> promise);
+
+  void request_password_recovery(Promise<tl_object_ptr<td_api::passwordRecoveryInfo>> promise);
+  void recover_password(string code, Promise<State> promise);
+
+  void get_temp_password_state(Promise<TempState> promise) /*const*/;
+  void create_temp_password(string password, int32 timeout, Promise<TempState> promise);
+  void drop_temp_password();
+
+  static TempPasswordState get_temp_password_state_sync();
+
+ private:
+  ActorShared<> parent_;
+
+  struct PasswordState {
+    bool has_password = false;
+    string password_hint;
+    bool has_recovery_email_address = false;
+    string unconfirmed_recovery_email_address_pattern = "";
+
+    string current_salt;
+    string new_salt;
+
+    State as_td_api() const {
+      return td_api::make_object<td_api::passwordState>(has_password, password_hint, has_recovery_email_address,
+                                                        unconfirmed_recovery_email_address_pattern);
+    }
+  };
+
+  struct UpdateSettings {
+    string current_password;
+
+    bool update_password = false;
+    string new_password;
+    string new_hint;
+
+    bool update_recovery_email_address = false;
+    string recovery_email_address;
+  };
+
+  TempPasswordState temp_password_state_;
+  Promise<TempState> create_temp_password_promise_;
+
+  void update_password_settings(UpdateSettings update_settings, Promise<State> promise);
+  void do_update_password_settings(UpdateSettings update_settings, PasswordState state, Promise<bool> promise);
+  void do_get_state(Promise<PasswordState> promise);
+  void do_get_recovery_email_address(string password, PasswordState state,
+                                     Promise<tl_object_ptr<td_api::recoveryEmailAddress>> promise);
+
+  void do_create_temp_password(string password, int32 timeout, PasswordState &&password_state,
+                               Promise<TempPasswordState> promise);
+  void on_finish_create_temp_password(Result<TempPasswordState> result, bool dummy);
+
+  void on_result(NetQueryPtr query) override;
+
+  void start_up() override;
+
+  Container<Promise<NetQueryPtr>> container_;
+  void send_with_promise(NetQueryPtr query, Promise<NetQueryPtr> promise);
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Payments.cpp b/libs/tdlib/td/td/telegram/Payments.cpp
new file mode 100644
index 0000000000..2dc2d61913
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Payments.cpp
@@ -0,0 +1,774 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/Payments.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/ContactsManager.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/MessageId.h"
+#include "td/telegram/misc.h"
+#include "td/telegram/PasswordManager.h"
+#include "td/telegram/Td.h"
+#include "td/telegram/UpdatesManager.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/JsonBuilder.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+class SetBotShippingAnswerQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit SetBotShippingAnswerQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int64 shipping_query_id, const string &error_message,
+            vector<tl_object_ptr<telegram_api::shippingOption>> &&shipping_options) {
+    int32 flags = 0;
+    if (!error_message.empty()) {
+      flags |= telegram_api::messages_setBotShippingResults::ERROR_MASK;
+    }
+    if (!shipping_options.empty()) {
+      flags |= telegram_api::messages_setBotShippingResults::SHIPPING_OPTIONS_MASK;
+    }
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_setBotShippingResults(
+        flags, shipping_query_id, error_message, std::move(shipping_options)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_setBotShippingResults>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    if (!result) {
+      LOG(INFO) << "Sending answer to a shipping query has failed";
+    }
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SetBotPreCheckoutAnswerQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit SetBotPreCheckoutAnswerQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int64 pre_checkout_query_id, const string &error_message) {
+    int32 flags = 0;
+    if (!error_message.empty()) {
+      flags |= telegram_api::messages_setBotPrecheckoutResults::ERROR_MASK;
+    } else {
+      flags |= telegram_api::messages_setBotPrecheckoutResults::SUCCESS_MASK;
+    }
+
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_setBotPrecheckoutResults(
+        flags, false /*ignored*/, pre_checkout_query_id, error_message))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_setBotPrecheckoutResults>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    if (!result) {
+      LOG(INFO) << "Sending answer to a pre-checkout query has failed";
+    }
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+static tl_object_ptr<td_api::invoice> convert_invoice(tl_object_ptr<telegram_api::invoice> invoice) {
+  CHECK(invoice != nullptr);
+
+  vector<tl_object_ptr<td_api::labeledPricePart>> labeled_prices;
+  labeled_prices.reserve(invoice->prices_.size());
+  for (auto &labeled_price : invoice->prices_) {
+    labeled_prices.push_back(
+        make_tl_object<td_api::labeledPricePart>(std::move(labeled_price->label_), labeled_price->amount_));
+  }
+
+  bool is_test = (invoice->flags_ & telegram_api::invoice::TEST_MASK) != 0;
+  bool need_name = (invoice->flags_ & telegram_api::invoice::NAME_REQUESTED_MASK) != 0;
+  bool need_phone_number = (invoice->flags_ & telegram_api::invoice::PHONE_REQUESTED_MASK) != 0;
+  bool need_email_address = (invoice->flags_ & telegram_api::invoice::EMAIL_REQUESTED_MASK) != 0;
+  bool need_shipping_address = (invoice->flags_ & telegram_api::invoice::SHIPPING_ADDRESS_REQUESTED_MASK) != 0;
+  bool send_phone_number_to_provider = (invoice->flags_ & telegram_api::invoice::PHONE_TO_PROVIDER_MASK) != 0;
+  bool send_email_address_to_provider = (invoice->flags_ & telegram_api::invoice::EMAIL_TO_PROVIDER_MASK) != 0;
+  bool is_flexible = (invoice->flags_ & telegram_api::invoice::FLEXIBLE_MASK) != 0;
+  if (send_phone_number_to_provider) {
+    need_phone_number = true;
+  }
+  if (send_email_address_to_provider) {
+    need_email_address = true;
+  }
+  if (is_flexible) {
+    need_shipping_address = true;
+  }
+
+  return make_tl_object<td_api::invoice>(std::move(invoice->currency_), std::move(labeled_prices), is_test, need_name,
+                                         need_phone_number, need_email_address, need_shipping_address,
+                                         send_phone_number_to_provider, send_email_address_to_provider, is_flexible);
+}
+
+static tl_object_ptr<td_api::paymentsProviderStripe> convert_payment_provider(
+    const string &native_provider_name, tl_object_ptr<telegram_api::dataJSON> native_parameters) {
+  if (native_parameters == nullptr) {
+    return nullptr;
+  }
+
+  if (native_provider_name == "stripe") {
+    string data = native_parameters->data_;
+    auto r_value = json_decode(data);
+    if (r_value.is_error()) {
+      LOG(ERROR) << "Can't parse json object \"" << native_parameters->data_ << "\": " << r_value.error();
+      return nullptr;
+    }
+
+    auto value = r_value.move_as_ok();
+    if (value.type() != JsonValue::Type::Object) {
+      LOG(ERROR) << "Wrong JSON data \"" << native_parameters->data_ << '"';
+      return nullptr;
+    }
+
+    auto r_need_country = get_json_object_bool_field(value.get_object(), "need_country", false);
+    auto r_need_postal_code = get_json_object_bool_field(value.get_object(), "need_zip", false);
+    auto r_need_cardholder_name = get_json_object_bool_field(value.get_object(), "need_cardholder_name", false);
+    auto r_publishable_key = get_json_object_string_field(value.get_object(), "publishable_key", false);
+
+    if (value.get_object().size() != 4 || r_need_country.is_error() || r_need_postal_code.is_error() ||
+        r_need_cardholder_name.is_error() || r_publishable_key.is_error()) {
+      LOG(WARNING) << "Unsupported JSON data \"" << native_parameters->data_ << '"';
+      return nullptr;
+    }
+
+    return make_tl_object<td_api::paymentsProviderStripe>(r_publishable_key.move_as_ok(), r_need_country.move_as_ok(),
+                                                          r_need_postal_code.move_as_ok(),
+                                                          r_need_cardholder_name.move_as_ok());
+  }
+
+  return nullptr;
+}
+
+static tl_object_ptr<td_api::shippingAddress> convert_shipping_address(
+    tl_object_ptr<telegram_api::postAddress> address) {
+  if (address == nullptr) {
+    return nullptr;
+  }
+  return make_tl_object<td_api::shippingAddress>(std::move(address->country_iso2_), std::move(address->state_),
+                                                 std::move(address->city_), std::move(address->street_line1_),
+                                                 std::move(address->street_line2_), std::move(address->post_code_));
+}
+
+static tl_object_ptr<telegram_api::postAddress> convert_shipping_address(
+    tl_object_ptr<td_api::shippingAddress> address) {
+  if (address == nullptr) {
+    return nullptr;
+  }
+  return make_tl_object<telegram_api::postAddress>(std::move(address->country_code_), std::move(address->state_),
+                                                   std::move(address->city_), std::move(address->street_line1_),
+                                                   std::move(address->street_line2_), std::move(address->postal_code_));
+}
+
+static tl_object_ptr<td_api::orderInfo> convert_order_info(
+    tl_object_ptr<telegram_api::paymentRequestedInfo> order_info) {
+  if (order_info == nullptr) {
+    return nullptr;
+  }
+  return make_tl_object<td_api::orderInfo>(std::move(order_info->name_), std::move(order_info->phone_),
+                                           std::move(order_info->email_),
+                                           convert_shipping_address(std::move(order_info->shipping_address_)));
+}
+
+static tl_object_ptr<td_api::labeledPricePart> convert_labeled_price(
+    tl_object_ptr<telegram_api::labeledPrice> labeled_price) {
+  CHECK(labeled_price != nullptr);
+  return make_tl_object<td_api::labeledPricePart>(std::move(labeled_price->label_), labeled_price->amount_);
+}
+
+static tl_object_ptr<td_api::shippingOption> convert_shipping_option(
+    tl_object_ptr<telegram_api::shippingOption> shipping_option) {
+  if (shipping_option == nullptr) {
+    return nullptr;
+  }
+
+  return make_tl_object<td_api::shippingOption>(std::move(shipping_option->id_), std::move(shipping_option->title_),
+                                                transform(std::move(shipping_option->prices_), convert_labeled_price));
+}
+
+static tl_object_ptr<telegram_api::paymentRequestedInfo> convert_order_info(
+    tl_object_ptr<td_api::orderInfo> order_info) {
+  if (order_info == nullptr) {
+    return nullptr;
+  }
+  int32 flags = 0;
+  if (!order_info->name_.empty()) {
+    flags |= telegram_api::paymentRequestedInfo::NAME_MASK;
+  }
+  if (!order_info->phone_number_.empty()) {
+    flags |= telegram_api::paymentRequestedInfo::PHONE_MASK;
+  }
+  if (!order_info->email_address_.empty()) {
+    flags |= telegram_api::paymentRequestedInfo::EMAIL_MASK;
+  }
+  if (order_info->shipping_address_ != nullptr) {
+    flags |= telegram_api::paymentRequestedInfo::SHIPPING_ADDRESS_MASK;
+  }
+  return make_tl_object<telegram_api::paymentRequestedInfo>(
+      flags, std::move(order_info->name_), std::move(order_info->phone_number_), std::move(order_info->email_address_),
+      convert_shipping_address(std::move(order_info->shipping_address_)));
+}
+
+static tl_object_ptr<td_api::savedCredentials> convert_saved_credentials(
+    tl_object_ptr<telegram_api::paymentSavedCredentialsCard> saved_credentials) {
+  if (saved_credentials == nullptr) {
+    return nullptr;
+  }
+  return make_tl_object<td_api::savedCredentials>(std::move(saved_credentials->id_),
+                                                  std::move(saved_credentials->title_));
+}
+
+class GetPaymentFormQuery : public Td::ResultHandler {
+  Promise<tl_object_ptr<td_api::paymentForm>> promise_;
+
+ public:
+  explicit GetPaymentFormQuery(Promise<tl_object_ptr<td_api::paymentForm>> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(ServerMessageId server_message_id) {
+    send_query(
+        G()->net_query_creator().create(create_storer(telegram_api::payments_getPaymentForm(server_message_id.get()))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::payments_getPaymentForm>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto payment_form = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive payment form: " << to_string(payment_form);
+
+    td->contacts_manager_->on_get_users(std::move(payment_form->users_));
+
+    bool can_save_credentials =
+        (payment_form->flags_ & telegram_api::payments_paymentForm::CAN_SAVE_CREDENTIALS_MASK) != 0;
+    bool need_password = (payment_form->flags_ & telegram_api::payments_paymentForm::PASSWORD_MISSING_MASK) != 0;
+    promise_.set_value(make_tl_object<td_api::paymentForm>(
+        convert_invoice(std::move(payment_form->invoice_)), std::move(payment_form->url_),
+        convert_payment_provider(payment_form->native_provider_, std::move(payment_form->native_params_)),
+        convert_order_info(std::move(payment_form->saved_info_)),
+        convert_saved_credentials(std::move(payment_form->saved_credentials_)), can_save_credentials, need_password));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ValidateRequestedInfoQuery : public Td::ResultHandler {
+  Promise<tl_object_ptr<td_api::validatedOrderInfo>> promise_;
+
+ public:
+  explicit ValidateRequestedInfoQuery(Promise<tl_object_ptr<td_api::validatedOrderInfo>> &&promise)
+      : promise_(std::move(promise)) {
+  }
+
+  void send(ServerMessageId server_message_id, tl_object_ptr<telegram_api::paymentRequestedInfo> requested_info,
+            bool allow_save) {
+    int32 flags = 0;
+    if (allow_save) {
+      flags |= telegram_api::payments_validateRequestedInfo::SAVE_MASK;
+    }
+    if (requested_info == nullptr) {
+      requested_info = make_tl_object<telegram_api::paymentRequestedInfo>();
+      requested_info->flags_ = 0;
+    }
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::payments_validateRequestedInfo(
+        flags, false /*ignored*/, server_message_id.get(), std::move(requested_info)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::payments_validateRequestedInfo>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto validated_order_info = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive validated order info: " << to_string(validated_order_info);
+
+    promise_.set_value(make_tl_object<td_api::validatedOrderInfo>(
+        std::move(validated_order_info->id_),
+        transform(std::move(validated_order_info->shipping_options_), convert_shipping_option)));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SendPaymentFormQuery : public Td::ResultHandler {
+  Promise<tl_object_ptr<td_api::paymentResult>> promise_;
+
+ public:
+  explicit SendPaymentFormQuery(Promise<tl_object_ptr<td_api::paymentResult>> &&promise)
+      : promise_(std::move(promise)) {
+  }
+
+  void send(ServerMessageId server_message_id, const string &order_info_id, const string &shipping_option_id,
+            tl_object_ptr<telegram_api::InputPaymentCredentials> input_credentials) {
+    CHECK(input_credentials != nullptr);
+    int32 flags = 0;
+    if (!order_info_id.empty()) {
+      flags |= telegram_api::payments_sendPaymentForm::REQUESTED_INFO_ID_MASK;
+    }
+    if (!shipping_option_id.empty()) {
+      flags |= telegram_api::payments_sendPaymentForm::SHIPPING_OPTION_ID_MASK;
+    }
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::payments_sendPaymentForm(
+        flags, server_message_id.get(), order_info_id, shipping_option_id, std::move(input_credentials)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::payments_sendPaymentForm>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto payment_result = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive payment result: " << to_string(payment_result);
+
+    switch (payment_result->get_id()) {
+      case telegram_api::payments_paymentResult::ID: {
+        auto result = move_tl_object_as<telegram_api::payments_paymentResult>(payment_result);
+        G()->td().get_actor_unsafe()->updates_manager_->on_get_updates(std::move(result->updates_));
+        promise_.set_value(make_tl_object<td_api::paymentResult>(true, string()));
+        return;
+      }
+      case telegram_api::payments_paymentVerficationNeeded::ID: {
+        auto result = move_tl_object_as<telegram_api::payments_paymentVerficationNeeded>(payment_result);
+        promise_.set_value(make_tl_object<td_api::paymentResult>(false, std::move(result->url_)));
+        return;
+      }
+      default:
+        UNREACHABLE();
+    }
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetPaymentReceiptQuery : public Td::ResultHandler {
+  Promise<tl_object_ptr<td_api::paymentReceipt>> promise_;
+
+ public:
+  explicit GetPaymentReceiptQuery(Promise<tl_object_ptr<td_api::paymentReceipt>> &&promise)
+      : promise_(std::move(promise)) {
+  }
+
+  void send(ServerMessageId server_message_id) {
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::payments_getPaymentReceipt(server_message_id.get()))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::payments_getPaymentReceipt>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto payment_receipt = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive payment receipt: " << to_string(payment_receipt);
+
+    td->contacts_manager_->on_get_users(std::move(payment_receipt->users_));
+
+    UserId payments_provider_user_id(payment_receipt->provider_id_);
+    if (!payments_provider_user_id.is_valid()) {
+      LOG(ERROR) << "Receive invalid payments provider " << payments_provider_user_id;
+      payments_provider_user_id = UserId();
+    }
+
+    promise_.set_value(make_tl_object<td_api::paymentReceipt>(
+        payment_receipt->date_,
+        G()->td().get_actor_unsafe()->contacts_manager_->get_user_id_object(payments_provider_user_id,
+                                                                            "paymentReceipt"),
+        convert_invoice(std::move(payment_receipt->invoice_)), convert_order_info(std::move(payment_receipt->info_)),
+        convert_shipping_option(std::move(payment_receipt->shipping_)),
+        std::move(payment_receipt->credentials_title_)));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetSavedInfoQuery : public Td::ResultHandler {
+  Promise<tl_object_ptr<td_api::orderInfo>> promise_;
+
+ public:
+  explicit GetSavedInfoQuery(Promise<tl_object_ptr<td_api::orderInfo>> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::payments_getSavedInfo())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::payments_getSavedInfo>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto saved_info = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive saved info: " << to_string(saved_info);
+    promise_.set_value(convert_order_info(std::move(saved_info->saved_info_)));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ClearSavedInfoQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit ClearSavedInfoQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(bool clear_credentials, bool clear_order_info) {
+    CHECK(clear_credentials || clear_order_info);
+    int32 flags = 0;
+    if (clear_credentials) {
+      flags |= telegram_api::payments_clearSavedInfo::CREDENTIALS_MASK;
+    }
+    if (clear_order_info) {
+      flags |= telegram_api::payments_clearSavedInfo::INFO_MASK;
+    }
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::payments_clearSavedInfo(flags, false /*ignored*/, false /*ignored*/))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::payments_clearSavedInfo>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+bool operator==(const LabeledPricePart &lhs, const LabeledPricePart &rhs) {
+  return lhs.label == rhs.label && lhs.amount == rhs.amount;
+}
+
+bool operator!=(const LabeledPricePart &lhs, const LabeledPricePart &rhs) {
+  return !(lhs == rhs);
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const LabeledPricePart &labeled_price_part) {
+  return string_builder << "[" << labeled_price_part.label << ": " << labeled_price_part.amount << "]";
+}
+
+bool operator==(const Invoice &lhs, const Invoice &rhs) {
+  return lhs.is_test == rhs.is_test && lhs.need_name == rhs.need_name &&
+         lhs.need_phone_number == rhs.need_phone_number && lhs.need_email_address == rhs.need_email_address &&
+         lhs.need_shipping_address == rhs.need_shipping_address &&
+         lhs.send_phone_number_to_provider == rhs.send_phone_number_to_provider &&
+         lhs.send_email_address_to_provider == rhs.send_email_address_to_provider &&
+         lhs.is_flexible == rhs.is_flexible && lhs.currency == rhs.currency && lhs.price_parts == rhs.price_parts;
+}
+
+bool operator!=(const Invoice &lhs, const Invoice &rhs) {
+  return !(lhs == rhs);
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const Invoice &invoice) {
+  return string_builder << "[" << (invoice.is_flexible ? "Flexible" : "") << (invoice.is_test ? "Test" : "")
+                        << "Invoice" << (invoice.need_name ? ", needs name" : "")
+                        << (invoice.need_phone_number ? ", needs phone number" : "")
+                        << (invoice.need_email_address ? ", needs email address" : "")
+                        << (invoice.need_shipping_address ? ", needs shipping address" : "")
+                        << (invoice.send_phone_number_to_provider ? ", sends phone number to provider" : "")
+                        << (invoice.send_email_address_to_provider ? ", sends email address to provider" : "") << " in "
+                        << invoice.currency << " with price parts " << format::as_array(invoice.price_parts) << "]";
+}
+
+bool operator==(const ShippingAddress &lhs, const ShippingAddress &rhs) {
+  return lhs.country_code == rhs.country_code && lhs.state == rhs.state && lhs.city == rhs.city &&
+         lhs.street_line1 == rhs.street_line1 && lhs.street_line2 == rhs.street_line2 &&
+         lhs.postal_code == rhs.postal_code;
+}
+
+bool operator!=(const ShippingAddress &lhs, const ShippingAddress &rhs) {
+  return !(lhs == rhs);
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const ShippingAddress &shipping_address) {
+  return string_builder << "[Address " << tag("country_code", shipping_address.country_code)
+                        << tag("state", shipping_address.state) << tag("city", shipping_address.city)
+                        << tag("street_line1", shipping_address.street_line1)
+                        << tag("street_line2", shipping_address.street_line2)
+                        << tag("postal_code", shipping_address.postal_code) << "]";
+}
+
+unique_ptr<ShippingAddress> get_shipping_address(tl_object_ptr<telegram_api::postAddress> address) {
+  if (address == nullptr) {
+    return nullptr;
+  }
+  return make_unique<ShippingAddress>(std::move(address->country_iso2_), std::move(address->state_),
+                                      std::move(address->city_), std::move(address->street_line1_),
+                                      std::move(address->street_line2_), std::move(address->post_code_));
+}
+
+tl_object_ptr<td_api::shippingAddress> get_shipping_address_object(
+    const unique_ptr<ShippingAddress> &shipping_address) {
+  if (shipping_address == nullptr) {
+    return nullptr;
+  }
+  return make_tl_object<td_api::shippingAddress>(shipping_address->country_code, shipping_address->state,
+                                                 shipping_address->city, shipping_address->street_line1,
+                                                 shipping_address->street_line2, shipping_address->postal_code);
+}
+
+bool operator==(const OrderInfo &lhs, const OrderInfo &rhs) {
+  return lhs.name == rhs.name && lhs.phone_number == rhs.phone_number && lhs.email_address == rhs.email_address &&
+         ((lhs.shipping_address == nullptr && rhs.shipping_address == nullptr) ||
+          (lhs.shipping_address != nullptr && rhs.shipping_address != nullptr &&
+           *lhs.shipping_address == *rhs.shipping_address));
+}
+
+bool operator!=(const OrderInfo &lhs, const OrderInfo &rhs) {
+  return !(lhs == rhs);
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const OrderInfo &order_info) {
+  string_builder << "[OrderInfo " << tag("name", order_info.name) << tag("phone_number", order_info.phone_number)
+                 << tag("email_address", order_info.email_address);
+  if (order_info.shipping_address != nullptr) {
+    string_builder << *order_info.shipping_address;
+  }
+  return string_builder << "]";
+}
+
+unique_ptr<OrderInfo> get_order_info(tl_object_ptr<telegram_api::paymentRequestedInfo> order_info) {
+  if (order_info == nullptr || order_info->flags_ == 0) {
+    return nullptr;
+  }
+  return make_unique<OrderInfo>(std::move(order_info->name_), std::move(order_info->phone_),
+                                std::move(order_info->email_),
+                                get_shipping_address(std::move(order_info->shipping_address_)));
+}
+
+tl_object_ptr<td_api::orderInfo> get_order_info_object(const unique_ptr<OrderInfo> &order_info) {
+  if (order_info == nullptr) {
+    return nullptr;
+  }
+  return make_tl_object<td_api::orderInfo>(order_info->name, order_info->phone_number, order_info->email_address,
+                                           get_shipping_address_object(order_info->shipping_address));
+}
+
+bool operator==(const ShippingOption &lhs, const ShippingOption &rhs) {
+  return lhs.id == rhs.id && lhs.title == rhs.title && lhs.price_parts == rhs.price_parts;
+}
+
+bool operator!=(const ShippingOption &lhs, const ShippingOption &rhs) {
+  return !(lhs == rhs);
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const ShippingOption &shipping_option) {
+  return string_builder << "[ShippingOption " << shipping_option.id << " " << shipping_option.title
+                        << " with price parts " << format::as_array(shipping_option.price_parts) << "]";
+}
+
+void answer_shipping_query(int64 shipping_query_id, vector<tl_object_ptr<td_api::shippingOption>> &&shipping_options,
+                           const string &error_message, Promise<Unit> &&promise) {
+  vector<tl_object_ptr<telegram_api::shippingOption>> options;
+  for (auto &option : shipping_options) {
+    if (option == nullptr) {
+      return promise.set_error(Status::Error(400, "Shipping option must not be empty"));
+    }
+    if (!clean_input_string(option->id_)) {
+      return promise.set_error(Status::Error(400, "Shipping option id must be encoded in UTF-8"));
+    }
+    if (!clean_input_string(option->title_)) {
+      return promise.set_error(Status::Error(400, "Shipping option title must be encoded in UTF-8"));
+    }
+
+    vector<tl_object_ptr<telegram_api::labeledPrice>> prices;
+    for (auto &price_part : option->price_parts_) {
+      if (price_part == nullptr) {
+        return promise.set_error(Status::Error(400, "Shipping option price part must not be empty"));
+      }
+      if (!clean_input_string(price_part->label_)) {
+        return promise.set_error(Status::Error(400, "Shipping option price part label must be encoded in UTF-8"));
+      }
+
+      prices.push_back(make_tl_object<telegram_api::labeledPrice>(std::move(price_part->label_), price_part->amount_));
+    }
+
+    options.push_back(make_tl_object<telegram_api::shippingOption>(std::move(option->id_), std::move(option->title_),
+                                                                   std::move(prices)));
+  }
+
+  G()->td()
+      .get_actor_unsafe()
+      ->create_handler<SetBotShippingAnswerQuery>(std::move(promise))
+      ->send(shipping_query_id, error_message, std::move(options));
+}
+
+void answer_pre_checkout_query(int64 pre_checkout_query_id, const string &error_message, Promise<Unit> &&promise) {
+  G()->td()
+      .get_actor_unsafe()
+      ->create_handler<SetBotPreCheckoutAnswerQuery>(std::move(promise))
+      ->send(pre_checkout_query_id, error_message);
+}
+
+void get_payment_form(ServerMessageId server_message_id, Promise<tl_object_ptr<td_api::paymentForm>> &&promise) {
+  G()->td().get_actor_unsafe()->create_handler<GetPaymentFormQuery>(std::move(promise))->send(server_message_id);
+}
+
+void validate_order_info(ServerMessageId server_message_id, tl_object_ptr<td_api::orderInfo> order_info,
+                         bool allow_save, Promise<tl_object_ptr<td_api::validatedOrderInfo>> &&promise) {
+  if (order_info != nullptr) {
+    if (!clean_input_string(order_info->name_)) {
+      return promise.set_error(Status::Error(400, "Name must be encoded in UTF-8"));
+    }
+    if (!clean_input_string(order_info->phone_number_)) {
+      return promise.set_error(Status::Error(400, "Phone number must be encoded in UTF-8"));
+    }
+    if (!clean_input_string(order_info->email_address_)) {
+      return promise.set_error(Status::Error(400, "Email address must be encoded in UTF-8"));
+    }
+    if (order_info->shipping_address_ != nullptr) {
+      if (!clean_input_string(order_info->shipping_address_->country_code_)) {
+        return promise.set_error(Status::Error(400, "Country code must be encoded in UTF-8"));
+      }
+      if (!clean_input_string(order_info->shipping_address_->state_)) {
+        return promise.set_error(Status::Error(400, "State must be encoded in UTF-8"));
+      }
+      if (!clean_input_string(order_info->shipping_address_->city_)) {
+        return promise.set_error(Status::Error(400, "City must be encoded in UTF-8"));
+      }
+      if (!clean_input_string(order_info->shipping_address_->street_line1_)) {
+        return promise.set_error(Status::Error(400, "Street address must be encoded in UTF-8"));
+      }
+      if (!clean_input_string(order_info->shipping_address_->street_line2_)) {
+        return promise.set_error(Status::Error(400, "Street address must be encoded in UTF-8"));
+      }
+      if (!clean_input_string(order_info->shipping_address_->postal_code_)) {
+        return promise.set_error(Status::Error(400, "Postal code must be encoded in UTF-8"));
+      }
+    }
+  }
+
+  G()->td()
+      .get_actor_unsafe()
+      ->create_handler<ValidateRequestedInfoQuery>(std::move(promise))
+      ->send(server_message_id, convert_order_info(std::move(order_info)), allow_save);
+}
+
+void send_payment_form(ServerMessageId server_message_id, const string &order_info_id, const string &shipping_option_id,
+                       const tl_object_ptr<td_api::InputCredentials> &credentials,
+                       Promise<tl_object_ptr<td_api::paymentResult>> &&promise) {
+  CHECK(credentials != nullptr);
+
+  tl_object_ptr<telegram_api::InputPaymentCredentials> input_credentials;
+  switch (credentials->get_id()) {
+    case td_api::inputCredentialsSaved::ID: {
+      auto credentials_saved = static_cast<const td_api::inputCredentialsSaved *>(credentials.get());
+      auto credentials_id = credentials_saved->saved_credentials_id_;
+      if (!clean_input_string(credentials_id)) {
+        return promise.set_error(Status::Error(400, "Credentials id must be encoded in UTF-8"));
+      }
+      auto temp_password_state =
+          G()->td().get_actor_unsafe()->password_manager_->get_actor_unsafe()->get_temp_password_state_sync();
+      if (!temp_password_state.has_temp_password) {
+        return promise.set_error(Status::Error(400, "Temporary password required to use saved credentials"));
+      }
+
+      input_credentials = make_tl_object<telegram_api::inputPaymentCredentialsSaved>(
+          std::move(credentials_id), BufferSlice(temp_password_state.temp_password));
+      break;
+    }
+    case td_api::inputCredentialsNew::ID: {
+      auto credentials_new = static_cast<const td_api::inputCredentialsNew *>(credentials.get());
+      int32 flags = 0;
+      if (credentials_new->allow_save_) {
+        flags |= telegram_api::inputPaymentCredentials::SAVE_MASK;
+      }
+
+      input_credentials = make_tl_object<telegram_api::inputPaymentCredentials>(
+          flags, false /*ignored*/, make_tl_object<telegram_api::dataJSON>(credentials_new->data_));
+      break;
+    }
+    case td_api::inputCredentialsAndroidPay::ID: {
+      auto credentials_android_pay = static_cast<const td_api::inputCredentialsAndroidPay *>(credentials.get());
+      input_credentials = make_tl_object<telegram_api::inputPaymentCredentialsAndroidPay>(
+          make_tl_object<telegram_api::dataJSON>(credentials_android_pay->data_), string());
+      break;
+    }
+    case td_api::inputCredentialsApplePay::ID: {
+      auto credentials_apple_pay = static_cast<const td_api::inputCredentialsApplePay *>(credentials.get());
+      input_credentials = make_tl_object<telegram_api::inputPaymentCredentialsApplePay>(
+          make_tl_object<telegram_api::dataJSON>(credentials_apple_pay->data_));
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+
+  G()->td()
+      .get_actor_unsafe()
+      ->create_handler<SendPaymentFormQuery>(std::move(promise))
+      ->send(server_message_id, order_info_id, shipping_option_id, std::move(input_credentials));
+}
+
+void get_payment_receipt(ServerMessageId server_message_id, Promise<tl_object_ptr<td_api::paymentReceipt>> &&promise) {
+  G()->td().get_actor_unsafe()->create_handler<GetPaymentReceiptQuery>(std::move(promise))->send(server_message_id);
+}
+
+void get_saved_order_info(Promise<tl_object_ptr<td_api::orderInfo>> &&promise) {
+  G()->td().get_actor_unsafe()->create_handler<GetSavedInfoQuery>(std::move(promise))->send();
+}
+
+void delete_saved_order_info(Promise<Unit> &&promise) {
+  G()->td().get_actor_unsafe()->create_handler<ClearSavedInfoQuery>(std::move(promise))->send(false, true);
+}
+
+void delete_saved_credentials(Promise<Unit> &&promise) {
+  G()->td().get_actor_unsafe()->create_handler<ClearSavedInfoQuery>(std::move(promise))->send(true, false);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Payments.h b/libs/tdlib/td/td/telegram/Payments.h
new file mode 100644
index 0000000000..8b61bb145f
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Payments.h
@@ -0,0 +1,146 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/MessageId.h"
+#include "td/telegram/Photo.h"
+
+#include "td/utils/common.h"
+#include "td/utils/StringBuilder.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+namespace td {
+
+struct LabeledPricePart {
+  string label;
+  int64 amount = 0;
+
+  LabeledPricePart() = default;
+  LabeledPricePart(string &&label, int64 amount) : label(std::move(label)), amount(amount) {
+  }
+};
+
+struct Invoice {
+  string currency;
+  vector<LabeledPricePart> price_parts;
+  bool is_test = false;
+  bool need_name = false;
+  bool need_phone_number = false;
+  bool need_email_address = false;
+  bool need_shipping_address = false;
+  bool send_phone_number_to_provider = false;
+  bool send_email_address_to_provider = false;
+  bool is_flexible = false;
+
+  Invoice() = default;
+  Invoice(string &&currency, bool is_test, bool need_shipping_address)
+      : currency(std::move(currency)), is_test(is_test), need_shipping_address(need_shipping_address) {
+  }
+};
+
+struct ShippingAddress {
+  string country_code;
+  string state;
+  string city;
+  string street_line1;
+  string street_line2;
+  string postal_code;
+
+  ShippingAddress() = default;
+  ShippingAddress(string &&country_code, string &&state, string &&city, string &&street_line1, string &&street_line2,
+                  string &&postal_code)
+      : country_code(std::move(country_code))
+      , state(std::move(state))
+      , city(std::move(city))
+      , street_line1(std::move(street_line1))
+      , street_line2(std::move(street_line2))
+      , postal_code(std::move(postal_code)) {
+  }
+};
+
+struct OrderInfo {
+  string name;
+  string phone_number;
+  string email_address;
+  unique_ptr<ShippingAddress> shipping_address;
+
+  OrderInfo() = default;
+  OrderInfo(string &&name, string &&phone_number, string &&email_address,
+            unique_ptr<ShippingAddress> &&shipping_address)
+      : name(std::move(name))
+      , phone_number(std::move(phone_number))
+      , email_address(std::move(email_address))
+      , shipping_address(std::move(shipping_address)) {
+  }
+};
+
+struct ShippingOption {
+  string id;
+  string title;
+  vector<LabeledPricePart> price_parts;
+};
+
+bool operator==(const LabeledPricePart &lhs, const LabeledPricePart &rhs);
+bool operator!=(const LabeledPricePart &lhs, const LabeledPricePart &rhs);
+
+StringBuilder &operator<<(StringBuilder &string_builder, const LabeledPricePart &labeled_price_part);
+
+bool operator==(const Invoice &lhs, const Invoice &rhs);
+bool operator!=(const Invoice &lhs, const Invoice &rhs);
+
+StringBuilder &operator<<(StringBuilder &string_builder, const Invoice &invoice);
+
+bool operator==(const ShippingAddress &lhs, const ShippingAddress &rhs);
+bool operator!=(const ShippingAddress &lhs, const ShippingAddress &rhs);
+
+StringBuilder &operator<<(StringBuilder &string_builder, const ShippingAddress &shipping_address);
+
+unique_ptr<ShippingAddress> get_shipping_address(tl_object_ptr<telegram_api::postAddress> address);
+
+tl_object_ptr<td_api::shippingAddress> get_shipping_address_object(const unique_ptr<ShippingAddress> &shipping_address);
+
+bool operator==(const OrderInfo &lhs, const OrderInfo &rhs);
+bool operator!=(const OrderInfo &lhs, const OrderInfo &rhs);
+
+StringBuilder &operator<<(StringBuilder &string_builder, const OrderInfo &order_info);
+
+unique_ptr<OrderInfo> get_order_info(tl_object_ptr<telegram_api::paymentRequestedInfo> order_info);
+
+tl_object_ptr<td_api::orderInfo> get_order_info_object(const unique_ptr<OrderInfo> &order_info);
+
+bool operator==(const ShippingOption &lhs, const ShippingOption &rhs);
+bool operator!=(const ShippingOption &lhs, const ShippingOption &rhs);
+
+StringBuilder &operator<<(StringBuilder &string_builder, const ShippingOption &shipping_option);
+
+void answer_shipping_query(int64 shipping_query_id, vector<tl_object_ptr<td_api::shippingOption>> &&shipping_options,
+                           const string &error_message, Promise<Unit> &&promise);
+
+void answer_pre_checkout_query(int64 pre_checkout_query_id, const string &error_message, Promise<Unit> &&promise);
+
+void get_payment_form(ServerMessageId server_message_id, Promise<tl_object_ptr<td_api::paymentForm>> &&promise);
+
+void validate_order_info(ServerMessageId server_message_id, tl_object_ptr<td_api::orderInfo> order_info,
+                         bool allow_save, Promise<tl_object_ptr<td_api::validatedOrderInfo>> &&promise);
+
+void send_payment_form(ServerMessageId server_message_id, const string &order_info_id, const string &shipping_option_id,
+                       const tl_object_ptr<td_api::InputCredentials> &credentials,
+                       Promise<tl_object_ptr<td_api::paymentResult>> &&promise);
+
+void get_payment_receipt(ServerMessageId server_message_id, Promise<tl_object_ptr<td_api::paymentReceipt>> &&promise);
+
+void get_saved_order_info(Promise<tl_object_ptr<td_api::orderInfo>> &&promise);
+
+void delete_saved_order_info(Promise<Unit> &&promise);
+
+void delete_saved_credentials(Promise<Unit> &&promise);
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Payments.hpp b/libs/tdlib/td/td/telegram/Payments.hpp
new file mode 100644
index 0000000000..e37773ca57
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Payments.hpp
@@ -0,0 +1,134 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/Payments.h"
+
+#include "td/telegram/Photo.hpp"
+
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+
+template <class StorerT>
+void store(const LabeledPricePart &labeled_price_part, StorerT &storer) {
+  store(labeled_price_part.label, storer);
+  store(labeled_price_part.amount, storer);
+}
+
+template <class ParserT>
+void parse(LabeledPricePart &labeled_price_part, ParserT &parser) {
+  parse(labeled_price_part.label, parser);
+  parse(labeled_price_part.amount, parser);
+}
+
+template <class StorerT>
+void store(const Invoice &invoice, StorerT &storer) {
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(invoice.is_test);
+  STORE_FLAG(invoice.need_name);
+  STORE_FLAG(invoice.need_phone_number);
+  STORE_FLAG(invoice.need_email_address);
+  STORE_FLAG(invoice.need_shipping_address);
+  STORE_FLAG(invoice.is_flexible);
+  STORE_FLAG(invoice.send_phone_number_to_provider);
+  STORE_FLAG(invoice.send_email_address_to_provider);
+  END_STORE_FLAGS();
+  store(invoice.currency, storer);
+  store(invoice.price_parts, storer);
+}
+
+template <class ParserT>
+void parse(Invoice &invoice, ParserT &parser) {
+  BEGIN_PARSE_FLAGS();
+  PARSE_FLAG(invoice.is_test);
+  PARSE_FLAG(invoice.need_name);
+  PARSE_FLAG(invoice.need_phone_number);
+  PARSE_FLAG(invoice.need_email_address);
+  PARSE_FLAG(invoice.need_shipping_address);
+  PARSE_FLAG(invoice.is_flexible);
+  PARSE_FLAG(invoice.send_phone_number_to_provider);
+  PARSE_FLAG(invoice.send_email_address_to_provider);
+  END_PARSE_FLAGS();
+  parse(invoice.currency, parser);
+  parse(invoice.price_parts, parser);
+}
+
+template <class StorerT>
+void store(const ShippingAddress &shipping_address, StorerT &storer) {
+  store(shipping_address.country_code, storer);
+  store(shipping_address.state, storer);
+  store(shipping_address.city, storer);
+  store(shipping_address.street_line1, storer);
+  store(shipping_address.street_line2, storer);
+  store(shipping_address.postal_code, storer);
+}
+
+template <class ParserT>
+void parse(ShippingAddress &shipping_address, ParserT &parser) {
+  parse(shipping_address.country_code, parser);
+  parse(shipping_address.state, parser);
+  parse(shipping_address.city, parser);
+  parse(shipping_address.street_line1, parser);
+  parse(shipping_address.street_line2, parser);
+  parse(shipping_address.postal_code, parser);
+}
+
+template <class StorerT>
+void store(const OrderInfo &order_info, StorerT &storer) {
+  bool has_name = !order_info.name.empty();
+  bool has_phone_number = !order_info.phone_number.empty();
+  bool has_email_address = !order_info.email_address.empty();
+  bool has_shipping_address = order_info.shipping_address != nullptr;
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(has_name);
+  STORE_FLAG(has_phone_number);
+  STORE_FLAG(has_email_address);
+  STORE_FLAG(has_shipping_address);
+  END_STORE_FLAGS();
+  if (has_name) {
+    store(order_info.name, storer);
+  }
+  if (has_phone_number) {
+    store(order_info.phone_number, storer);
+  }
+  if (has_email_address) {
+    store(order_info.email_address, storer);
+  }
+  if (has_shipping_address) {
+    store(*order_info.shipping_address, storer);
+  }
+}
+
+template <class ParserT>
+void parse(OrderInfo &order_info, ParserT &parser) {
+  bool has_name;
+  bool has_phone_number;
+  bool has_email_address;
+  bool has_shipping_address;
+  BEGIN_PARSE_FLAGS();
+  PARSE_FLAG(has_name);
+  PARSE_FLAG(has_phone_number);
+  PARSE_FLAG(has_email_address);
+  PARSE_FLAG(has_shipping_address);
+  END_PARSE_FLAGS();
+  if (has_name) {
+    parse(order_info.name, parser);
+  }
+  if (has_phone_number) {
+    parse(order_info.phone_number, parser);
+  }
+  if (has_email_address) {
+    parse(order_info.email_address, parser);
+  }
+  if (has_shipping_address) {
+    order_info.shipping_address = make_unique<ShippingAddress>();
+    parse(*order_info.shipping_address, parser);
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Photo.cpp b/libs/tdlib/td/td/telegram/Photo.cpp
new file mode 100644
index 0000000000..f08007a87a
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Photo.cpp
@@ -0,0 +1,604 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/Photo.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/files/FileManager.h"
+#include "td/telegram/Global.h"
+
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/HttpUrl.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Random.h"
+
+#include <algorithm>
+#include <limits>
+
+namespace td {
+
+static uint16 get_dimension(int32 size) {
+  if (size < 0 || size > 65535) {
+    LOG(ERROR) << "Wrong image dimension = " << size;
+    return 0;
+  }
+  return narrow_cast<uint16>(size);
+}
+
+Dimensions get_dimensions(int32 width, int32 height) {
+  Dimensions result;
+  result.width = get_dimension(width);
+  result.height = get_dimension(height);
+  if (result.width == 0 || result.height == 0) {
+    result.width = 0;
+    result.height = 0;
+  }
+  return result;
+}
+
+bool operator==(const Dimensions &lhs, const Dimensions &rhs) {
+  return lhs.width == rhs.width && lhs.height == rhs.height;
+}
+
+bool operator!=(const Dimensions &lhs, const Dimensions &rhs) {
+  return !(lhs == rhs);
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const Dimensions &dimensions) {
+  return string_builder << "(" << dimensions.width << ", " << dimensions.height << ")";
+}
+
+static FileId register_photo(FileManager *file_manager, FileType file_type, int64 id, int64 access_hash,
+                             tl_object_ptr<telegram_api::FileLocation> &&location_ptr, DialogId owner_dialog_id,
+                             int32 file_size) {
+  int32 location_id = location_ptr->get_id();
+  DcId dc_id;
+  int32 local_id;
+  int64 volume_id;
+  int64 secret;
+  switch (location_id) {
+    case telegram_api::fileLocationUnavailable::ID: {
+      auto location = move_tl_object_as<telegram_api::fileLocationUnavailable>(location_ptr);
+      dc_id = DcId::invalid();
+      local_id = location->local_id_;
+      volume_id = location->volume_id_;
+      secret = location->secret_;
+      break;
+    }
+    case telegram_api::fileLocation::ID: {
+      auto location = move_tl_object_as<telegram_api::fileLocation>(location_ptr);
+      if (!DcId::is_valid(location->dc_id_)) {
+        dc_id = DcId::invalid();
+      } else {
+        dc_id = DcId::internal(location->dc_id_);
+      }
+      local_id = location->local_id_;
+      volume_id = location->volume_id_;
+      secret = location->secret_;
+      break;
+    }
+    default:
+      UNREACHABLE();
+      break;
+  }
+
+  LOG(DEBUG) << "Receive photo of type " << static_cast<int8>(file_type) << " in [" << dc_id << "," << volume_id << ","
+             << local_id << "]. Id: (" << id << ", " << access_hash << ")";
+  auto suggested_name = PSTRING() << static_cast<uint64>(volume_id) << "_" << static_cast<uint64>(local_id) << ".jpg";
+  return file_manager->register_remote(
+      FullRemoteFileLocation(file_type, id, access_hash, local_id, volume_id, secret, dc_id),
+      FileLocationSource::FromServer, owner_dialog_id, file_size, 0, std::move(suggested_name));
+}
+
+ProfilePhoto get_profile_photo(FileManager *file_manager,
+                               tl_object_ptr<telegram_api::UserProfilePhoto> &&profile_photo_ptr) {
+  ProfilePhoto result;
+  int32 profile_photo_id =
+      profile_photo_ptr == nullptr ? telegram_api::userProfilePhotoEmpty::ID : profile_photo_ptr->get_id();
+  switch (profile_photo_id) {
+    case telegram_api::userProfilePhotoEmpty::ID:
+      break;
+    case telegram_api::userProfilePhoto::ID: {
+      auto profile_photo = move_tl_object_as<telegram_api::userProfilePhoto>(profile_photo_ptr);
+
+      result.id = profile_photo->photo_id_;
+      result.small_file_id = register_photo(file_manager, FileType::ProfilePhoto, result.id, 0,
+                                            std::move(profile_photo->photo_small_), DialogId(), 0);
+      result.big_file_id = register_photo(file_manager, FileType::ProfilePhoto, result.id, 0,
+                                          std::move(profile_photo->photo_big_), DialogId(), 0);
+      break;
+    }
+    default:
+      UNREACHABLE();
+      break;
+  }
+
+  return result;
+}
+
+tl_object_ptr<td_api::profilePhoto> get_profile_photo_object(FileManager *file_manager,
+                                                             const ProfilePhoto *profile_photo) {
+  if (profile_photo == nullptr || !profile_photo->small_file_id.is_valid()) {
+    return nullptr;
+  }
+  return make_tl_object<td_api::profilePhoto>(profile_photo->id,
+                                              file_manager->get_file_object(profile_photo->small_file_id),
+                                              file_manager->get_file_object(profile_photo->big_file_id));
+}
+
+bool operator==(const ProfilePhoto &lhs, const ProfilePhoto &rhs) {
+  bool location_differs = lhs.small_file_id != rhs.small_file_id || lhs.big_file_id != rhs.big_file_id;
+  bool id_differs;
+  if (lhs.id == -1 && rhs.id == -1) {
+    // group chat photo
+    id_differs = location_differs;
+  } else {
+    id_differs = lhs.id != rhs.id;
+  }
+
+  if (location_differs) {
+    LOG_IF(ERROR, !id_differs) << "location_differs = true, but id_differs = false. First profilePhoto: " << lhs
+                               << ", second profilePhoto: " << rhs;
+    return false;
+  }
+  return true;
+}
+
+bool operator!=(const ProfilePhoto &lhs, const ProfilePhoto &rhs) {
+  return !(lhs == rhs);
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const ProfilePhoto &profile_photo) {
+  return string_builder << "<id = " << profile_photo.id << ", small_file_id = " << profile_photo.small_file_id
+                        << ", big_file_id = " << profile_photo.big_file_id << ">";
+}
+
+DialogPhoto get_dialog_photo(FileManager *file_manager, tl_object_ptr<telegram_api::ChatPhoto> &&chat_photo_ptr) {
+  int32 chat_photo_id = chat_photo_ptr == nullptr ? telegram_api::chatPhotoEmpty::ID : chat_photo_ptr->get_id();
+
+  DialogPhoto result;
+  switch (chat_photo_id) {
+    case telegram_api::chatPhotoEmpty::ID:
+      break;
+    case telegram_api::chatPhoto::ID: {
+      auto chat_photo = move_tl_object_as<telegram_api::chatPhoto>(chat_photo_ptr);
+
+      result.small_file_id = register_photo(file_manager, FileType::ProfilePhoto, 0, 0,
+                                            std::move(chat_photo->photo_small_), DialogId(), 0);
+      result.big_file_id =
+          register_photo(file_manager, FileType::ProfilePhoto, 0, 0, std::move(chat_photo->photo_big_), DialogId(), 0);
+
+      break;
+    }
+    default:
+      UNREACHABLE();
+      break;
+  }
+
+  return result;
+}
+
+tl_object_ptr<td_api::chatPhoto> get_chat_photo_object(FileManager *file_manager, const DialogPhoto *dialog_photo) {
+  if (dialog_photo == nullptr || !dialog_photo->small_file_id.is_valid()) {
+    return nullptr;
+  }
+  return make_tl_object<td_api::chatPhoto>(file_manager->get_file_object(dialog_photo->small_file_id),
+                                           file_manager->get_file_object(dialog_photo->big_file_id));
+}
+
+bool operator==(const DialogPhoto &lhs, const DialogPhoto &rhs) {
+  return lhs.small_file_id == rhs.small_file_id && lhs.big_file_id == rhs.big_file_id;
+}
+
+bool operator!=(const DialogPhoto &lhs, const DialogPhoto &rhs) {
+  return !(lhs == rhs);
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const DialogPhoto &dialog_photo) {
+  return string_builder << "<small_file_id = " << dialog_photo.small_file_id
+                        << ", big_file_id = " << dialog_photo.big_file_id << ">";
+}
+
+PhotoSize get_thumbnail_photo_size(FileManager *file_manager, BufferSlice bytes, DialogId owner_dialog_id, int32 width,
+                                   int32 height) {
+  if (bytes.empty()) {
+    return PhotoSize();
+  }
+  PhotoSize res;
+  res.type = 't';
+  res.dimensions = get_dimensions(width, height);
+  res.size = narrow_cast<int32>(bytes.size());
+
+  // generate some random remote location to save
+  auto dc_id = DcId::invalid();
+  auto local_id = Random::secure_int32();
+  auto volume_id = Random::secure_int64();
+  auto secret = 0;
+  res.file_id = file_manager->register_remote(
+      FullRemoteFileLocation(FileType::EncryptedThumbnail, 0, 0, local_id, volume_id, secret, dc_id),
+      FileLocationSource::FromServer, owner_dialog_id, res.size, 0,
+      PSTRING() << static_cast<uint64>(volume_id) << "_" << static_cast<uint64>(local_id) << ".jpg");
+  file_manager->set_content(res.file_id, std::move(bytes));
+
+  return res;
+}
+
+PhotoSize get_photo_size(FileManager *file_manager, FileType file_type, int64 id, int64 access_hash,
+                         DialogId owner_dialog_id, tl_object_ptr<telegram_api::PhotoSize> &&size_ptr) {
+  tl_object_ptr<telegram_api::FileLocation> location_ptr;
+  string type;
+
+  PhotoSize res;
+  BufferSlice content;
+
+  int32 size_id = size_ptr->get_id();
+  switch (size_id) {
+    case telegram_api::photoSizeEmpty::ID:
+      return res;
+    case telegram_api::photoSize::ID: {
+      auto size = move_tl_object_as<telegram_api::photoSize>(size_ptr);
+
+      type = std::move(size->type_);
+      location_ptr = std::move(size->location_);
+      res.dimensions = get_dimensions(size->w_, size->h_);
+      res.size = size->size_;
+
+      break;
+    }
+    case telegram_api::photoCachedSize::ID: {
+      auto size = move_tl_object_as<telegram_api::photoCachedSize>(size_ptr);
+
+      type = std::move(size->type_);
+      location_ptr = std::move(size->location_);
+      CHECK(size->bytes_.size() <= static_cast<size_t>(std::numeric_limits<int32>::max()));
+      res.dimensions = get_dimensions(size->w_, size->h_);
+      res.size = static_cast<int32>(size->bytes_.size());
+
+      content = std::move(size->bytes_);
+
+      break;
+    }
+
+    default:
+      UNREACHABLE();
+      break;
+  }
+
+  res.file_id =
+      register_photo(file_manager, file_type, id, access_hash, std::move(location_ptr), owner_dialog_id, res.size);
+
+  if (!content.empty()) {
+    file_manager->set_content(res.file_id, std::move(content));
+  }
+
+  if (type.size() != 1) {
+    res.type = 0;
+    LOG(ERROR) << "Wrong photoSize " << res;
+  } else {
+    res.type = static_cast<int32>(type[0]);
+  }
+
+  return res;
+}
+
+PhotoSize get_web_document_photo_size(FileManager *file_manager, FileType file_type, DialogId owner_dialog_id,
+                                      tl_object_ptr<telegram_api::WebDocument> web_document_ptr) {
+  if (web_document_ptr == nullptr) {
+    return {};
+  }
+
+  FileId file_id;
+  vector<tl_object_ptr<telegram_api::DocumentAttribute>> attributes;
+  int32 size = 0;
+  switch (web_document_ptr->get_id()) {
+    case telegram_api::webDocument::ID: {
+      auto web_document = move_tl_object_as<telegram_api::webDocument>(web_document_ptr);
+      if (!DcId::is_valid(web_document->dc_id_)) {
+        LOG(ERROR) << "Wrong dc_id = " << web_document->dc_id_;
+        return {};
+      }
+
+      auto r_http_url = parse_url(web_document->url_);
+      if (r_http_url.is_error()) {
+        LOG(ERROR) << "Can't parse URL " << web_document->url_;
+        return {};
+      }
+      auto http_url = r_http_url.move_as_ok();
+      auto url = http_url.get_url();
+      file_id = file_manager->register_remote(
+          FullRemoteFileLocation(file_type, url, web_document->access_hash_, DcId::internal(web_document->dc_id_)),
+          FileLocationSource::FromServer, owner_dialog_id, 0, web_document->size_,
+          get_url_query_file_name(http_url.query_));
+
+      size = web_document->size_;
+      attributes = std::move(web_document->attributes_);
+      break;
+    }
+    case telegram_api::webDocumentNoProxy::ID: {
+      auto web_document = move_tl_object_as<telegram_api::webDocumentNoProxy>(web_document_ptr);
+      if (web_document->url_.find('.') == string::npos) {
+        LOG(ERROR) << "Receive invalid URL " << web_document->url_;
+        return {};
+      }
+
+      auto r_file_id = file_manager->from_persistent_id(web_document->url_, file_type);
+      if (r_file_id.is_error()) {
+        LOG(ERROR) << "Can't register URL: " << r_file_id.error();
+        return {};
+      }
+      file_id = r_file_id.move_as_ok();
+
+      size = web_document->size_;
+      attributes = std::move(web_document->attributes_);
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+  CHECK(file_id.is_valid());
+
+  Dimensions dimensions;
+  for (auto &attribute : attributes) {
+    switch (attribute->get_id()) {
+      case telegram_api::documentAttributeImageSize::ID: {
+        auto image_size = move_tl_object_as<telegram_api::documentAttributeImageSize>(attribute);
+        dimensions = get_dimensions(image_size->w_, image_size->h_);
+        break;
+      }
+      case telegram_api::documentAttributeAnimated::ID:
+      case telegram_api::documentAttributeHasStickers::ID:
+      case telegram_api::documentAttributeSticker::ID:
+      case telegram_api::documentAttributeVideo::ID:
+      case telegram_api::documentAttributeAudio::ID:
+        LOG(ERROR) << "Unexpected web document attribute " << to_string(attribute);
+        break;
+      case telegram_api::documentAttributeFilename::ID:
+        break;
+      default:
+        UNREACHABLE();
+    }
+  }
+
+  PhotoSize s;
+  s.type = file_type == FileType::Thumbnail ? 't' : 'u';
+  s.dimensions = dimensions;
+  s.size = size;
+  s.file_id = file_id;
+  return s;
+}
+
+tl_object_ptr<td_api::photoSize> get_photo_size_object(FileManager *file_manager, const PhotoSize *photo_size) {
+  if (photo_size == nullptr || !photo_size->file_id.is_valid()) {
+    return nullptr;
+  }
+
+  return make_tl_object<td_api::photoSize>(
+      photo_size->type ? std::string(1, static_cast<char>(photo_size->type))
+                       : std::string(),  // TODO replace string type with integer type
+      file_manager->get_file_object(photo_size->file_id), photo_size->dimensions.width, photo_size->dimensions.height);
+}
+
+void sort_photo_sizes(vector<td_api::object_ptr<td_api::photoSize>> &sizes) {
+  std::sort(sizes.begin(), sizes.end(), [](const auto &lhs, const auto &rhs) {
+    if (lhs->photo_->expected_size_ != rhs->photo_->expected_size_) {
+      return lhs->photo_->expected_size_ < rhs->photo_->expected_size_;
+    }
+    return lhs->width_ * lhs->height_ < rhs->width_ * rhs->height_;
+  });
+}
+
+bool operator==(const PhotoSize &lhs, const PhotoSize &rhs) {
+  return lhs.type == rhs.type && lhs.dimensions == rhs.dimensions && lhs.size == rhs.size && lhs.file_id == rhs.file_id;
+}
+
+bool operator!=(const PhotoSize &lhs, const PhotoSize &rhs) {
+  return !(lhs == rhs);
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const PhotoSize &photo_size) {
+  return string_builder << "{type = " << photo_size.type << ", dimensions = " << photo_size.dimensions
+                        << ", size = " << photo_size.size << ", file_id = " << photo_size.file_id << "}";
+}
+
+Photo get_photo(FileManager *file_manager, tl_object_ptr<telegram_api::encryptedFile> &&file,
+                tl_object_ptr<secret_api::decryptedMessageMediaPhoto> &&photo, DialogId owner_dialog_id) {
+  CHECK(DcId::is_valid(file->dc_id_));
+  FileId file_id = file_manager->register_remote(
+      FullRemoteFileLocation(FileType::Encrypted, file->id_, file->access_hash_, DcId::internal(file->dc_id_)),
+      FileLocationSource::FromServer, owner_dialog_id, photo->size_, 0,
+      PSTRING() << static_cast<uint64>(file->id_) << ".jpg");
+  file_manager->set_encryption_key(file_id, FileEncryptionKey{photo->key_.as_slice(), photo->iv_.as_slice()});
+
+  Photo res;
+  res.date = 0;
+
+  if (!photo->thumb_.empty()) {
+    res.photos.push_back(get_thumbnail_photo_size(file_manager, std::move(photo->thumb_), owner_dialog_id,
+                                                  photo->thumb_w_, photo->thumb_h_));
+  }
+
+  PhotoSize s;
+  s.type = 'i';
+  s.dimensions = get_dimensions(photo->w_, photo->h_);
+  s.size = photo->size_;
+  s.file_id = file_id;
+  res.photos.push_back(s);
+
+  return res;
+}
+
+Photo get_photo(FileManager *file_manager, tl_object_ptr<telegram_api::photo> &&photo, DialogId owner_dialog_id) {
+  Photo res;
+
+  res.id = photo->id_;
+  res.date = photo->date_;
+  res.has_stickers = (photo->flags_ & telegram_api::photo::HAS_STICKERS_MASK) != 0;
+
+  for (auto &size_ptr : photo->sizes_) {
+    res.photos.push_back(get_photo_size(file_manager, FileType::Photo, photo->id_, photo->access_hash_, owner_dialog_id,
+                                        std::move(size_ptr)));
+  }
+
+  return res;
+}
+
+tl_object_ptr<td_api::photo> get_photo_object(FileManager *file_manager, const Photo *photo) {
+  if (photo == nullptr || photo->id == -2) {
+    return nullptr;
+  }
+
+  vector<td_api::object_ptr<td_api::photoSize>> photos;
+  for (auto &photo_size : photo->photos) {
+    photos.push_back(get_photo_size_object(file_manager, &photo_size));
+  }
+  sort_photo_sizes(photos);
+  return make_tl_object<td_api::photo>(photo->id, photo->has_stickers, std::move(photos));
+}
+
+void photo_delete_thumbnail(Photo &photo) {
+  for (size_t i = 0; i < photo.photos.size(); i++) {
+    if (photo.photos[i].type == 't') {
+      photo.photos.erase(photo.photos.begin() + i);
+    }
+  }
+}
+
+bool photo_has_input_media(FileManager *file_manager, const Photo &photo, bool is_secret) {
+  if (photo.photos.empty() || photo.photos.back().type != 'i') {
+    LOG(ERROR) << "Wrong photo: " << photo;
+    return false;
+  }
+  auto file_id = photo.photos.back().file_id;
+  auto file_view = file_manager->get_file_view(file_id);
+  if (is_secret) {
+    if (file_view.encryption_key().empty() || !file_view.has_remote_location()) {
+      return false;
+    }
+
+    for (const auto &size : photo.photos) {
+      if (size.type == 't' && size.file_id.is_valid()) {
+        return false;
+      }
+    }
+
+    return true;
+  } else {
+    if (file_view.is_encrypted()) {
+      return false;
+    }
+    return file_view.has_remote_location() || file_view.has_url();
+  }
+}
+
+tl_object_ptr<telegram_api::InputMedia> photo_get_input_media(FileManager *file_manager, const Photo &photo,
+                                                              tl_object_ptr<telegram_api::InputFile> input_file,
+                                                              int32 ttl) {
+  if (!photo.photos.empty()) {
+    auto file_id = photo.photos.back().file_id;
+    auto file_view = file_manager->get_file_view(file_id);
+    if (file_view.is_encrypted()) {
+      return nullptr;
+    }
+    if (file_view.has_remote_location() && !file_view.remote_location().is_web()) {
+      int32 flags = 0;
+      if (ttl != 0) {
+        flags |= telegram_api::inputMediaPhoto::TTL_SECONDS_MASK;
+      }
+      return make_tl_object<telegram_api::inputMediaPhoto>(flags, file_view.remote_location().as_input_photo(), ttl);
+    }
+    if (file_view.has_url()) {
+      int32 flags = 0;
+      if (ttl != 0) {
+        flags |= telegram_api::inputMediaPhotoExternal::TTL_SECONDS_MASK;
+      }
+      LOG(INFO) << "Create inputMediaPhotoExternal with a URL " << file_view.url() << " and ttl " << ttl;
+      return make_tl_object<telegram_api::inputMediaPhotoExternal>(flags, file_view.url(), ttl);
+    }
+    CHECK(!file_view.has_remote_location());
+  }
+  if (input_file != nullptr) {
+    int32 flags = 0;
+    vector<tl_object_ptr<telegram_api::InputDocument>> added_stickers;
+    if (photo.has_stickers) {
+      flags |= telegram_api::inputMediaUploadedPhoto::STICKERS_MASK;
+      added_stickers = file_manager->get_input_documents(photo.sticker_file_ids);
+    }
+    if (ttl != 0) {
+      flags |= telegram_api::inputMediaUploadedPhoto::TTL_SECONDS_MASK;
+    }
+
+    return make_tl_object<telegram_api::inputMediaUploadedPhoto>(flags, std::move(input_file),
+                                                                 std::move(added_stickers), ttl);
+  }
+  return nullptr;
+}
+
+SecretInputMedia photo_get_secret_input_media(FileManager *file_manager, const Photo &photo,
+                                              tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                              const string &caption, BufferSlice thumbnail) {
+  FileId file_id;
+  int32 width = 0;
+  int32 height = 0;
+
+  FileId thumbnail_file_id;
+  int32 thumbnail_width = 0;
+  int32 thumbnail_height = 0;
+  for (const auto &size : photo.photos) {
+    if (size.type == 'i') {
+      file_id = size.file_id;
+      width = size.dimensions.width;
+      height = size.dimensions.height;
+    }
+    if (size.type == 't') {
+      thumbnail_file_id = size.file_id;
+      thumbnail_width = size.dimensions.width;
+      thumbnail_height = size.dimensions.height;
+    }
+  }
+  if (file_id.empty()) {
+    LOG(ERROR) << "NO SIZE";
+    return {};
+  }
+  auto file_view = file_manager->get_file_view(file_id);
+  auto &encryption_key = file_view.encryption_key();
+  if (encryption_key.empty()) {
+    return {};
+  }
+  if (file_view.has_remote_location()) {
+    LOG(INFO) << "HAS REMOTE LOCATION";
+    input_file = file_view.remote_location().as_input_encrypted_file();
+  }
+  if (input_file == nullptr) {
+    return {};
+  }
+  if (thumbnail_file_id.is_valid() && thumbnail.empty()) {
+    return {};
+  }
+
+  return SecretInputMedia{
+      std::move(input_file),
+      make_tl_object<secret_api::decryptedMessageMediaPhoto>(
+          std::move(thumbnail), thumbnail_width, thumbnail_height, width, height, narrow_cast<int32>(file_view.size()),
+          BufferSlice(encryption_key.key_slice()), BufferSlice(encryption_key.iv_slice()), caption)};
+}
+
+bool operator==(const Photo &lhs, const Photo &rhs) {
+  return lhs.id == rhs.id && lhs.photos == rhs.photos;
+}
+
+bool operator!=(const Photo &lhs, const Photo &rhs) {
+  return !(lhs == rhs);
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const Photo &photo) {
+  return string_builder << "[id = " << photo.id << ", photos = " << format::as_array(photo.photos) << "]";
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Photo.h b/libs/tdlib/td/td/telegram/Photo.h
new file mode 100644
index 0000000000..f91911fd68
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Photo.h
@@ -0,0 +1,117 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/DialogId.h"
+#include "td/telegram/files/FileId.h"
+#include "td/telegram/files/FileLocation.h"
+#include "td/telegram/SecretInputMedia.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/StringBuilder.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+namespace td {
+
+class FileManager;
+
+struct Dimensions {
+  uint16 width = 0;
+  uint16 height = 0;
+};
+
+struct DialogPhoto {
+  FileId small_file_id;
+  FileId big_file_id;
+};
+
+struct ProfilePhoto : public DialogPhoto {
+  int64 id = 0;
+};
+
+struct PhotoSize {
+  int32 type = 0;  // TODO remove
+  Dimensions dimensions;
+  int32 size = 0;
+  FileId file_id;
+};
+
+struct Photo {
+  int64 id = 0;
+  int32 date = 0;
+  vector<PhotoSize> photos;
+
+  bool has_stickers = false;
+  vector<FileId> sticker_file_ids;
+};
+
+Dimensions get_dimensions(int32 width, int32 height);
+
+bool operator==(const Dimensions &lhs, const Dimensions &rhs);
+bool operator!=(const Dimensions &lhs, const Dimensions &rhs);
+
+StringBuilder &operator<<(StringBuilder &string_builder, const Dimensions &dimensions);
+
+ProfilePhoto get_profile_photo(FileManager *file_manager,
+                               tl_object_ptr<telegram_api::UserProfilePhoto> &&profile_photo_ptr);
+tl_object_ptr<td_api::profilePhoto> get_profile_photo_object(FileManager *file_manager,
+                                                             const ProfilePhoto *profile_photo);
+
+bool operator==(const ProfilePhoto &lhs, const ProfilePhoto &rhs);
+bool operator!=(const ProfilePhoto &lhs, const ProfilePhoto &rhs);
+
+StringBuilder &operator<<(StringBuilder &string_builder, const ProfilePhoto &profile_photo);
+
+DialogPhoto get_dialog_photo(FileManager *file_manager, tl_object_ptr<telegram_api::ChatPhoto> &&chat_photo_ptr);
+tl_object_ptr<td_api::chatPhoto> get_chat_photo_object(FileManager *file_manager, const DialogPhoto *dialog_photo);
+
+bool operator==(const DialogPhoto &lhs, const DialogPhoto &rhs);
+bool operator!=(const DialogPhoto &lhs, const DialogPhoto &rhs);
+
+StringBuilder &operator<<(StringBuilder &string_builder, const DialogPhoto &dialog_photo);
+
+PhotoSize get_thumbnail_photo_size(FileManager *file_manager, BufferSlice bytes, DialogId owner_dialog_id, int32 width,
+                                   int32 height);
+PhotoSize get_photo_size(FileManager *file_manager, FileType file_type, int64 id, int64 access_hash,
+                         DialogId owner_dialog_id, tl_object_ptr<telegram_api::PhotoSize> &&size_ptr);
+PhotoSize get_web_document_photo_size(FileManager *file_manager, FileType file_type, DialogId owner_dialog_id,
+                                      tl_object_ptr<telegram_api::WebDocument> web_document_ptr);
+tl_object_ptr<td_api::photoSize> get_photo_size_object(FileManager *file_manager, const PhotoSize *photo_size);
+void sort_photo_sizes(vector<td_api::object_ptr<td_api::photoSize>> &sizes);
+
+bool operator==(const PhotoSize &lhs, const PhotoSize &rhs);
+bool operator!=(const PhotoSize &lhs, const PhotoSize &rhs);
+
+StringBuilder &operator<<(StringBuilder &string_builder, const PhotoSize &photo_size);
+
+Photo get_photo(FileManager *file_manager, tl_object_ptr<telegram_api::photo> &&photo, DialogId owner_dialog_id);
+Photo get_photo(FileManager *file_manager, tl_object_ptr<telegram_api::encryptedFile> &&file,
+                tl_object_ptr<secret_api::decryptedMessageMediaPhoto> &&photo, DialogId owner_dialog_id);
+tl_object_ptr<td_api::photo> get_photo_object(FileManager *file_manager, const Photo *photo);
+
+void photo_delete_thumbnail(Photo &photo);
+
+bool photo_has_input_media(FileManager *file_manager, const Photo &photo, bool is_secret);
+
+SecretInputMedia photo_get_secret_input_media(FileManager *file_manager, const Photo &photo,
+                                              tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                              const string &caption, BufferSlice thumbnail);
+
+tl_object_ptr<telegram_api::InputMedia> photo_get_input_media(FileManager *file_manager, const Photo &photo,
+                                                              tl_object_ptr<telegram_api::InputFile> input_file,
+                                                              int32 ttl);
+
+bool operator==(const Photo &lhs, const Photo &rhs);
+bool operator!=(const Photo &lhs, const Photo &rhs);
+
+StringBuilder &operator<<(StringBuilder &string_builder, const Photo &photo);
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Photo.hpp b/libs/tdlib/td/td/telegram/Photo.hpp
new file mode 100644
index 0000000000..0b16d9c3c5
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Photo.hpp
@@ -0,0 +1,99 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/Photo.h"
+
+#include "td/telegram/files/FileId.hpp"
+
+#include "td/utils/logging.h"
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+
+template <class StorerT>
+void store(Dimensions dimensions, StorerT &storer) {
+  store(static_cast<uint32>((static_cast<uint32>(dimensions.width) << 16) | dimensions.height), storer);
+}
+
+template <class ParserT>
+void parse(Dimensions &dimensions, ParserT &parser) {
+  uint32 width_height;
+  parse(width_height, parser);
+  dimensions.width = static_cast<uint16>(width_height >> 16);
+  dimensions.height = static_cast<uint16>(width_height & 0xFFFF);
+}
+
+template <class StorerT>
+void store(const DialogPhoto &dialog_photo, StorerT &storer) {
+  store(dialog_photo.small_file_id, storer);
+  store(dialog_photo.big_file_id, storer);
+}
+
+template <class ParserT>
+void parse(DialogPhoto &dialog_photo, ParserT &parser) {
+  parse(dialog_photo.small_file_id, parser);
+  parse(dialog_photo.big_file_id, parser);
+}
+
+template <class StorerT>
+void store(const ProfilePhoto &profile_photo, StorerT &storer) {
+  store(static_cast<const DialogPhoto &>(profile_photo), storer);
+  store(profile_photo.id, storer);
+}
+
+template <class ParserT>
+void parse(ProfilePhoto &profile_photo, ParserT &parser) {
+  parse(static_cast<DialogPhoto &>(profile_photo), parser);
+  parse(profile_photo.id, parser);
+}
+
+template <class StorerT>
+void store(const PhotoSize &photo_size, StorerT &storer) {
+  LOG(DEBUG) << "Store photo size " << photo_size;
+  store(photo_size.type, storer);
+  store(photo_size.dimensions, storer);
+  store(photo_size.size, storer);
+  store(photo_size.file_id, storer);
+}
+
+template <class ParserT>
+void parse(PhotoSize &photo_size, ParserT &parser) {
+  parse(photo_size.type, parser);
+  parse(photo_size.dimensions, parser);
+  parse(photo_size.size, parser);
+  parse(photo_size.file_id, parser);
+  LOG(DEBUG) << "Parsed photo size " << photo_size;
+}
+
+template <class StorerT>
+void store(const Photo &photo, StorerT &storer) {
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(photo.has_stickers);
+  END_STORE_FLAGS();
+  store(photo.id, storer);
+  store(photo.date, storer);
+  store(photo.photos, storer);
+  if (photo.has_stickers) {
+    store(photo.sticker_file_ids, storer);
+  }
+}
+
+template <class ParserT>
+void parse(Photo &photo, ParserT &parser) {
+  BEGIN_PARSE_FLAGS();
+  PARSE_FLAG(photo.has_stickers);
+  END_PARSE_FLAGS();
+  parse(photo.id, parser);
+  parse(photo.date, parser);
+  parse(photo.photos, parser);
+  if (photo.has_stickers) {
+    parse(photo.sticker_file_ids, parser);
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/PrivacyManager.cpp b/libs/tdlib/td/td/telegram/PrivacyManager.cpp
new file mode 100644
index 0000000000..389d07cabf
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/PrivacyManager.cpp
@@ -0,0 +1,378 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/PrivacyManager.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/ContactsManager.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/net/NetQueryCreator.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+#include "td/telegram/Td.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+
+namespace td {
+
+Result<PrivacyManager::UserPrivacySetting> PrivacyManager::UserPrivacySetting::from_td_api(
+    tl_object_ptr<td_api::UserPrivacySetting> key) {
+  if (!key) {
+    return Status::Error(5, "UserPrivacySetting should not be empty");
+  }
+  return UserPrivacySetting(*key);
+}
+PrivacyManager::UserPrivacySetting::UserPrivacySetting(const telegram_api::PrivacyKey &key) {
+  switch (key.get_id()) {
+    case telegram_api::privacyKeyStatusTimestamp::ID:
+      type_ = Type::UserState;
+      break;
+    case telegram_api::privacyKeyChatInvite::ID:
+      type_ = Type::ChatInvite;
+      break;
+    case telegram_api::privacyKeyPhoneCall::ID:
+      type_ = Type::Call;
+      break;
+    default:
+      UNREACHABLE();
+      type_ = Type::UserState;
+  }
+}
+tl_object_ptr<td_api::UserPrivacySetting> PrivacyManager::UserPrivacySetting::as_td_api() const {
+  switch (type_) {
+    case Type::UserState:
+      return make_tl_object<td_api::userPrivacySettingShowStatus>();
+    case Type::ChatInvite:
+      return make_tl_object<td_api::userPrivacySettingAllowChatInvites>();
+    case Type::Call:
+      return make_tl_object<td_api::userPrivacySettingAllowCalls>();
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+tl_object_ptr<telegram_api::InputPrivacyKey> PrivacyManager::UserPrivacySetting::as_telegram_api() const {
+  switch (type_) {
+    case Type::UserState:
+      return make_tl_object<telegram_api::inputPrivacyKeyStatusTimestamp>();
+    case Type::ChatInvite:
+      return make_tl_object<telegram_api::inputPrivacyKeyChatInvite>();
+    case Type::Call:
+      return make_tl_object<telegram_api::inputPrivacyKeyPhoneCall>();
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+PrivacyManager::UserPrivacySetting::UserPrivacySetting(const td_api::UserPrivacySetting &key) {
+  switch (key.get_id()) {
+    case td_api::userPrivacySettingShowStatus::ID:
+      type_ = Type::UserState;
+      break;
+    case td_api::userPrivacySettingAllowChatInvites::ID:
+      type_ = Type::ChatInvite;
+      break;
+    case td_api::userPrivacySettingAllowCalls::ID:
+      type_ = Type::Call;
+      break;
+    default:
+      UNREACHABLE();
+      type_ = Type::UserState;
+  }
+}
+
+PrivacyManager::UserPrivacySettingRule::UserPrivacySettingRule(const td_api::UserPrivacySettingRule &rule) {
+  switch (rule.get_id()) {
+    case td_api::userPrivacySettingRuleAllowContacts::ID:
+      type_ = Type::AllowContacts;
+      break;
+    case td_api::userPrivacySettingRuleAllowAll::ID:
+      type_ = Type::AllowAll;
+      break;
+    case td_api::userPrivacySettingRuleAllowUsers::ID:
+      type_ = Type::AllowUsers;
+      user_ids_ = static_cast<const td_api::userPrivacySettingRuleAllowUsers &>(rule).user_ids_;
+      break;
+    case td_api::userPrivacySettingRuleRestrictContacts::ID:
+      type_ = Type::RestrictContacts;
+      break;
+    case td_api::userPrivacySettingRuleRestrictAll::ID:
+      type_ = Type::RestrictAll;
+      break;
+    case td_api::userPrivacySettingRuleRestrictUsers::ID:
+      type_ = Type::RestrictUsers;
+      user_ids_ = static_cast<const td_api::userPrivacySettingRuleRestrictUsers &>(rule).user_ids_;
+      break;
+    default:
+      UNREACHABLE();
+  }
+}
+
+PrivacyManager::UserPrivacySettingRule::UserPrivacySettingRule(const telegram_api::PrivacyRule &rule) {
+  switch (rule.get_id()) {
+    case telegram_api::privacyValueAllowContacts::ID:
+      type_ = Type::AllowContacts;
+      break;
+    case telegram_api::privacyValueAllowAll::ID:
+      type_ = Type::AllowAll;
+      break;
+    case telegram_api::privacyValueAllowUsers::ID:
+      type_ = Type::AllowUsers;
+      user_ids_ = static_cast<const telegram_api::privacyValueAllowUsers &>(rule).users_;
+      break;
+    case telegram_api::privacyValueDisallowContacts::ID:
+      type_ = Type::RestrictContacts;
+      break;
+    case telegram_api::privacyValueDisallowAll::ID:
+      type_ = Type::RestrictAll;
+      break;
+    case telegram_api::privacyValueDisallowUsers::ID:
+      type_ = Type::RestrictUsers;
+      user_ids_ = static_cast<const telegram_api::privacyValueDisallowUsers &>(rule).users_;
+      break;
+    default:
+      UNREACHABLE();
+  }
+}
+
+tl_object_ptr<td_api::UserPrivacySettingRule> PrivacyManager::UserPrivacySettingRule::as_td_api() const {
+  switch (type_) {
+    case Type::AllowContacts:
+      return make_tl_object<td_api::userPrivacySettingRuleAllowContacts>();
+    case Type::AllowAll:
+      return make_tl_object<td_api::userPrivacySettingRuleAllowAll>();
+    case Type::AllowUsers:
+      return make_tl_object<td_api::userPrivacySettingRuleAllowUsers>(user_ids_as_td_api());
+    case Type::RestrictContacts:
+      return make_tl_object<td_api::userPrivacySettingRuleRestrictContacts>();
+    case Type::RestrictAll:
+      return make_tl_object<td_api::userPrivacySettingRuleRestrictAll>();
+    case Type::RestrictUsers:
+      return make_tl_object<td_api::userPrivacySettingRuleRestrictUsers>(user_ids_as_td_api());
+    default:
+      UNREACHABLE();
+  }
+}
+
+tl_object_ptr<telegram_api::InputPrivacyRule> PrivacyManager::UserPrivacySettingRule::as_telegram_api() const {
+  switch (type_) {
+    case Type::AllowContacts:
+      return make_tl_object<telegram_api::inputPrivacyValueAllowContacts>();
+    case Type::AllowAll:
+      return make_tl_object<telegram_api::inputPrivacyValueAllowAll>();
+    case Type::AllowUsers:
+      return make_tl_object<telegram_api::inputPrivacyValueAllowUsers>(user_ids_as_telegram_api());
+    case Type::RestrictContacts:
+      return make_tl_object<telegram_api::inputPrivacyValueDisallowContacts>();
+    case Type::RestrictAll:
+      return make_tl_object<telegram_api::inputPrivacyValueDisallowAll>();
+    case Type::RestrictUsers:
+      return make_tl_object<telegram_api::inputPrivacyValueDisallowUsers>(user_ids_as_telegram_api());
+    default:
+      UNREACHABLE();
+  }
+}
+
+Result<PrivacyManager::UserPrivacySettingRule> PrivacyManager::UserPrivacySettingRule::from_telegram_api(
+    tl_object_ptr<telegram_api::PrivacyRule> rule) {
+  CHECK(rule != nullptr);
+  UserPrivacySettingRule res(*rule);
+  for (auto user_id : res.user_ids_) {
+    if (!G()->td().get_actor_unsafe()->contacts_manager_->have_user(UserId(user_id))) {
+      return Status::Error(500, "Got unaccessible user from the server");
+    }
+  }
+  return res;
+}
+
+vector<tl_object_ptr<telegram_api::InputUser>> PrivacyManager::UserPrivacySettingRule::user_ids_as_telegram_api()
+    const {
+  vector<tl_object_ptr<telegram_api::InputUser>> res;
+  for (auto user_id : user_ids_) {
+    auto input_user = G()->td().get_actor_unsafe()->contacts_manager_->get_input_user(UserId(user_id));
+    if (input_user != nullptr) {
+      res.push_back(std::move(input_user));
+    } else {
+      LOG(ERROR) << "Have no access to " << user_id;
+    }
+  }
+  return res;
+}
+
+vector<int32> PrivacyManager::UserPrivacySettingRule::user_ids_as_td_api() const {
+  return user_ids_;
+}
+
+Result<PrivacyManager::UserPrivacySettingRules> PrivacyManager::UserPrivacySettingRules::from_telegram_api(
+    tl_object_ptr<telegram_api::account_privacyRules> rules) {
+  G()->td().get_actor_unsafe()->contacts_manager_->on_get_users(std::move(rules->users_));
+  return from_telegram_api(std::move(rules->rules_));
+}
+
+Result<PrivacyManager::UserPrivacySettingRules> PrivacyManager::UserPrivacySettingRules::from_telegram_api(
+    vector<tl_object_ptr<telegram_api::PrivacyRule>> rules) {
+  UserPrivacySettingRules res;
+  for (auto &rule : rules) {
+    TRY_RESULT(new_rule, UserPrivacySettingRule::from_telegram_api(std::move(rule)));
+    res.rules_.push_back(new_rule);
+  }
+  return res;
+}
+
+Result<PrivacyManager::UserPrivacySettingRules> PrivacyManager::UserPrivacySettingRules::from_td_api(
+    tl_object_ptr<td_api::userPrivacySettingRules> rules) {
+  if (!rules) {
+    return Status::Error(5, "UserPrivacySettingRules should not be empty");
+  }
+  UserPrivacySettingRules res;
+  for (auto &rule : rules->rules_) {
+    if (!rule) {
+      return Status::Error(5, "UserPrivacySettingRule should not be empty");
+    }
+    res.rules_.emplace_back(*rule);
+  }
+  return res;
+}
+
+tl_object_ptr<td_api::userPrivacySettingRules> PrivacyManager::UserPrivacySettingRules::as_td_api() const {
+  return make_tl_object<td_api::userPrivacySettingRules>(
+      transform(rules_, [](const auto &rule) { return rule.as_td_api(); }));
+}
+
+vector<tl_object_ptr<telegram_api::InputPrivacyRule>> PrivacyManager::UserPrivacySettingRules::as_telegram_api() const {
+  return transform(rules_, [](const auto &rule) { return rule.as_telegram_api(); });
+}
+
+void PrivacyManager::get_privacy(tl_object_ptr<td_api::UserPrivacySetting> key,
+                                 Promise<tl_object_ptr<td_api::userPrivacySettingRules>> promise) {
+  auto r_user_privacy_setting = UserPrivacySetting::from_td_api(std::move(key));
+  if (r_user_privacy_setting.is_error()) {
+    return promise.set_error(r_user_privacy_setting.move_as_error());
+  }
+  auto user_privacy_setting = r_user_privacy_setting.move_as_ok();
+  auto &info = get_info(user_privacy_setting);
+  if (info.is_synchronized) {
+    return promise.set_value(info.rules.as_td_api());
+  }
+  info.get_promises.push_back(std::move(promise));
+  if (info.get_promises.size() > 1u) {
+    // query has already been sent, just wait for the result
+    return;
+  }
+  auto net_query = G()->net_query_creator().create(
+      create_storer(telegram_api::account_getPrivacy(user_privacy_setting.as_telegram_api())));
+
+  send_with_promise(std::move(net_query),
+                    PromiseCreator::lambda([this, user_privacy_setting](Result<NetQueryPtr> x_net_query) mutable {
+                      on_get_result(user_privacy_setting, [&]() -> Result<UserPrivacySettingRules> {
+                        TRY_RESULT(net_query, std::move(x_net_query));
+                        TRY_RESULT(rules, fetch_result<telegram_api::account_getPrivacy>(std::move(net_query)));
+                        return UserPrivacySettingRules::from_telegram_api(std::move(rules));
+                      }());
+                    }));
+}
+
+void PrivacyManager::set_privacy(tl_object_ptr<td_api::UserPrivacySetting> key,
+                                 tl_object_ptr<td_api::userPrivacySettingRules> rules,
+                                 Promise<tl_object_ptr<td_api::ok>> promise) {
+  auto r_user_privacy_setting = UserPrivacySetting::from_td_api(std::move(key));
+  if (r_user_privacy_setting.is_error()) {
+    return promise.set_error(r_user_privacy_setting.move_as_error());
+  }
+  auto user_privacy_setting = r_user_privacy_setting.move_as_ok();
+
+  auto r_privacy_rules = UserPrivacySettingRules::from_td_api(std::move(rules));
+  if (r_privacy_rules.is_error()) {
+    return promise.set_error(r_privacy_rules.move_as_error());
+  }
+  auto privacy_rules = r_privacy_rules.move_as_ok();
+
+  auto &info = get_info(user_privacy_setting);
+  if (info.has_set_query) {
+    // TODO cancel previous query
+    return promise.set_error(Status::Error(5, "Another set_privacy query is active"));
+  }
+  auto net_query = G()->net_query_creator().create(create_storer(
+      telegram_api::account_setPrivacy(user_privacy_setting.as_telegram_api(), privacy_rules.as_telegram_api())));
+
+  info.has_set_query = true;
+  send_with_promise(std::move(net_query),
+                    PromiseCreator::lambda([this, user_privacy_setting,
+                                            promise = std::move(promise)](Result<NetQueryPtr> x_net_query) mutable {
+                      promise.set_result([&]() -> Result<tl_object_ptr<td_api::ok>> {
+                        TRY_RESULT(net_query, std::move(x_net_query));
+                        TRY_RESULT(rules, fetch_result<telegram_api::account_setPrivacy>(std::move(net_query)));
+                        TRY_RESULT(privacy_rules, UserPrivacySettingRules::from_telegram_api(std::move(rules)));
+                        get_info(user_privacy_setting).has_set_query = false;
+                        do_update_privacy(user_privacy_setting, std::move(privacy_rules), true);
+                        return make_tl_object<td_api::ok>();
+                      }());
+                    }));
+}
+
+void PrivacyManager::update_privacy(tl_object_ptr<telegram_api::updatePrivacy> update) {
+  CHECK(update != nullptr);
+  CHECK(update->key_ != nullptr);
+  UserPrivacySetting user_privacy_setting(*update->key_);
+  auto r_privacy_rules = UserPrivacySettingRules::from_telegram_api(std::move(update->rules_));
+  if (r_privacy_rules.is_error()) {
+    LOG(INFO) << "Skip updatePrivacy: " << r_privacy_rules.error().message();
+    auto &info = get_info(user_privacy_setting);
+    info.is_synchronized = false;
+  } else {
+    do_update_privacy(user_privacy_setting, r_privacy_rules.move_as_ok(), true);
+  }
+}
+
+void PrivacyManager::on_get_result(UserPrivacySetting user_privacy_setting,
+                                   Result<UserPrivacySettingRules> privacy_rules) {
+  auto &info = get_info(user_privacy_setting);
+  auto promises = std::move(info.get_promises);
+  reset_to_empty(info.get_promises);
+  for (auto &promise : promises) {
+    if (privacy_rules.is_error()) {
+      promise.set_error(privacy_rules.error().clone());
+    } else {
+      promise.set_value(privacy_rules.ok().as_td_api());
+    }
+  }
+  if (privacy_rules.is_ok()) {
+    do_update_privacy(user_privacy_setting, privacy_rules.move_as_ok(), false);
+  }
+}
+
+void PrivacyManager::do_update_privacy(UserPrivacySetting user_privacy_setting, UserPrivacySettingRules &&privacy_rules,
+                                       bool from_update) {
+  auto &info = get_info(user_privacy_setting);
+  bool was_synchronized = info.is_synchronized;
+  info.is_synchronized = true;
+
+  if (!(info.rules == privacy_rules)) {
+    info.rules = std::move(privacy_rules);
+    send_closure(G()->td(), &Td::send_update,
+                 make_tl_object<td_api::updateUserPrivacySettingRules>(user_privacy_setting.as_td_api(),
+                                                                       info.rules.as_td_api()));
+
+    if ((from_update || was_synchronized) && user_privacy_setting.type() == UserPrivacySetting::Type::UserState) {
+      send_closure(G()->contacts_manager(), &ContactsManager::on_update_online_status_privacy);
+    }
+  }
+}
+
+void PrivacyManager::on_result(NetQueryPtr query) {
+  auto token = get_link_token();
+  container_.extract(token).set_value(std::move(query));
+}
+
+void PrivacyManager::send_with_promise(NetQueryPtr query, Promise<NetQueryPtr> promise) {
+  auto id = container_.create(std::move(promise));
+  G()->net_query_dispatcher().dispatch_with_callback(std::move(query), actor_shared(this, id));
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/PrivacyManager.h b/libs/tdlib/td/td/telegram/PrivacyManager.h
new file mode 100644
index 0000000000..820e435afb
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/PrivacyManager.h
@@ -0,0 +1,127 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Container.h"
+#include "td/utils/Status.h"
+
+#include <array>
+
+namespace td {
+
+class PrivacyManager : public NetQueryCallback {
+ public:
+  explicit PrivacyManager(ActorShared<> parent) : parent_(std::move(parent)) {
+  }
+
+  void get_privacy(tl_object_ptr<td_api::UserPrivacySetting> key,
+                   Promise<tl_object_ptr<td_api::userPrivacySettingRules>> promise);
+
+  void set_privacy(tl_object_ptr<td_api::UserPrivacySetting> key, tl_object_ptr<td_api::userPrivacySettingRules> rules,
+                   Promise<tl_object_ptr<td_api::ok>> promise);
+
+  void update_privacy(tl_object_ptr<telegram_api::updatePrivacy> update);
+
+ private:
+  class UserPrivacySetting {
+   public:
+    enum class Type : int32 { UserState, ChatInvite, Call, Size };
+
+    static Result<UserPrivacySetting> from_td_api(tl_object_ptr<td_api::UserPrivacySetting> key);
+    explicit UserPrivacySetting(const telegram_api::PrivacyKey &key);
+    tl_object_ptr<td_api::UserPrivacySetting> as_td_api() const;
+    tl_object_ptr<telegram_api::InputPrivacyKey> as_telegram_api() const;
+
+    Type type() const {
+      return type_;
+    }
+
+   private:
+    Type type_;
+
+    explicit UserPrivacySetting(const td_api::UserPrivacySetting &key);
+  };
+
+  class UserPrivacySettingRule {
+   public:
+    UserPrivacySettingRule() = default;
+    static Result<UserPrivacySettingRule> from_telegram_api(tl_object_ptr<telegram_api::PrivacyRule> rule);
+    explicit UserPrivacySettingRule(const td_api::UserPrivacySettingRule &rule);
+    tl_object_ptr<td_api::UserPrivacySettingRule> as_td_api() const;
+    tl_object_ptr<telegram_api::InputPrivacyRule> as_telegram_api() const;
+
+    bool operator==(const UserPrivacySettingRule &other) const {
+      return type_ == other.type_ && user_ids_ == other.user_ids_;
+    }
+
+   private:
+    enum class Type {
+      AllowContacts,
+      AllowAll,
+      AllowUsers,
+      RestrictContacts,
+      RestrictAll,
+      RestrictUsers
+    } type_ = Type::RestrictAll;
+
+    vector<int32> user_ids_;
+
+    vector<int32> user_ids_as_td_api() const;
+
+    vector<tl_object_ptr<telegram_api::InputUser>> user_ids_as_telegram_api() const;
+
+    explicit UserPrivacySettingRule(const telegram_api::PrivacyRule &rule);
+  };
+
+  class UserPrivacySettingRules {
+   public:
+    UserPrivacySettingRules() = default;
+    static Result<UserPrivacySettingRules> from_telegram_api(tl_object_ptr<telegram_api::account_privacyRules> rules);
+    static Result<UserPrivacySettingRules> from_telegram_api(vector<tl_object_ptr<telegram_api::PrivacyRule>> rules);
+    static Result<UserPrivacySettingRules> from_td_api(tl_object_ptr<td_api::userPrivacySettingRules> rules);
+    tl_object_ptr<td_api::userPrivacySettingRules> as_td_api() const;
+    vector<tl_object_ptr<telegram_api::InputPrivacyRule>> as_telegram_api() const;
+
+    bool operator==(const UserPrivacySettingRules &other) const {
+      return rules_ == other.rules_;
+    }
+
+   private:
+    vector<UserPrivacySettingRule> rules_;
+  };
+
+  ActorShared<> parent_;
+
+  struct PrivacyInfo {
+    UserPrivacySettingRules rules;
+    vector<Promise<tl_object_ptr<td_api::userPrivacySettingRules>>> get_promises;
+    bool has_set_query = false;
+    bool is_synchronized = false;
+  };
+  std::array<PrivacyInfo, static_cast<size_t>(UserPrivacySetting::Type::Size)> info_;
+
+  PrivacyInfo &get_info(UserPrivacySetting key) {
+    return info_[static_cast<size_t>(key.type())];
+  }
+
+  void on_get_result(UserPrivacySetting user_privacy_setting, Result<UserPrivacySettingRules> privacy_rules);
+  void do_update_privacy(UserPrivacySetting user_privacy_setting, UserPrivacySettingRules &&privacy_rules,
+                         bool from_update);
+
+  void on_result(NetQueryPtr query) override;
+  Container<Promise<NetQueryPtr>> container_;
+  void send_with_promise(NetQueryPtr query, Promise<NetQueryPtr> promise);
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/PtsManager.h b/libs/tdlib/td/td/telegram/PtsManager.h
new file mode 100644
index 0000000000..c7c50409cc
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/PtsManager.h
@@ -0,0 +1,57 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/ChangesProcessor.h"
+#include "td/utils/logging.h"
+
+namespace td {
+// It is not about handling gaps.
+// It is about finding mem processed pts.
+// All checks must be done before.
+
+class PtsManager {
+ public:
+  using PtsId = ChangesProcessor<int32>::Id;
+  void init(int32 pts) {
+    db_pts_ = pts;
+    mem_pts_ = pts;
+    state_helper_.clear();
+  }
+
+  // 0 if not a checkpoint
+  PtsId add_pts(int32 pts) {
+    CHECK(pts >= 0);
+    if (pts != 0) {
+      mem_pts_ = pts;
+    }
+    return state_helper_.add(pts);
+  }
+
+  // return db_pts
+  int32 finish(PtsId pts_id) {
+    state_helper_.finish(pts_id, [&](int32 pts) {
+      if (pts != 0) {
+        db_pts_ = pts;
+      }
+    });
+    return db_pts_;
+  }
+
+  int32 db_pts() const {
+    return db_pts_;
+  }
+  int32 mem_pts() const {
+    return mem_pts_;
+  }
+
+ private:
+  int32 db_pts_ = -1;
+  int32 mem_pts_ = -1;
+  ChangesProcessor<int32> state_helper_;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/ReplyMarkup.cpp b/libs/tdlib/td/td/telegram/ReplyMarkup.cpp
new file mode 100644
index 0000000000..110331f2bc
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/ReplyMarkup.cpp
@@ -0,0 +1,713 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/ReplyMarkup.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/misc.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/format.h"
+#include "td/utils/HttpUrl.h"
+#include "td/utils/logging.h"
+
+namespace td {
+
+static constexpr int32 REPLY_MARKUP_FLAG_NEED_RESIZE_KEYBOARD = 1 << 0;
+static constexpr int32 REPLY_MARKUP_FLAG_IS_ONE_TIME_KEYBOARD = 1 << 1;
+static constexpr int32 REPLY_MARKUP_FLAG_IS_PERSONAL = 1 << 2;
+
+static bool operator==(const KeyboardButton &lhs, const KeyboardButton &rhs) {
+  return lhs.type == rhs.type && lhs.text == rhs.text;
+}
+
+static StringBuilder &operator<<(StringBuilder &string_builder, const KeyboardButton &keyboard_button) {
+  string_builder << "Button[";
+  switch (keyboard_button.type) {
+    case KeyboardButton::Type::Text:
+      string_builder << "Text";
+      break;
+    case KeyboardButton::Type::RequestPhoneNumber:
+      string_builder << "RequestPhoneNumber";
+      break;
+    case KeyboardButton::Type::RequestLocation:
+      string_builder << "RequestLocation";
+      break;
+    default:
+      UNREACHABLE();
+  }
+  return string_builder << ", " << keyboard_button.text << "]";
+}
+
+static bool operator==(const InlineKeyboardButton &lhs, const InlineKeyboardButton &rhs) {
+  return lhs.type == rhs.type && lhs.text == rhs.text && lhs.data == rhs.data;
+}
+
+static StringBuilder &operator<<(StringBuilder &string_builder, const InlineKeyboardButton &keyboard_button) {
+  string_builder << "Button[";
+  switch (keyboard_button.type) {
+    case InlineKeyboardButton::Type::Url:
+      string_builder << "Url";
+      break;
+    case InlineKeyboardButton::Type::Callback:
+      string_builder << "Callback";
+      break;
+    case InlineKeyboardButton::Type::CallbackGame:
+      string_builder << "CallbackGame";
+      break;
+    case InlineKeyboardButton::Type::SwitchInline:
+      string_builder << "SwitchInline";
+      break;
+    case InlineKeyboardButton::Type::SwitchInlineCurrentDialog:
+      string_builder << "SwitchInlineCurrentChat";
+      break;
+    case InlineKeyboardButton::Type::Buy:
+      string_builder << "Buy";
+      break;
+    default:
+      UNREACHABLE();
+  }
+  return string_builder << ", text = " << keyboard_button.text << ", " << keyboard_button.data << "]";
+}
+
+bool operator==(const ReplyMarkup &lhs, const ReplyMarkup &rhs) {
+  if (lhs.type != rhs.type) {
+    return false;
+  }
+  if (lhs.type == ReplyMarkup::Type::InlineKeyboard) {
+    return lhs.inline_keyboard == rhs.inline_keyboard;
+  }
+
+  if (lhs.is_personal != rhs.is_personal) {
+    return false;
+  }
+  if (lhs.type != ReplyMarkup::Type::ShowKeyboard) {
+    return true;
+  }
+  return lhs.need_resize_keyboard == rhs.need_resize_keyboard && lhs.is_one_time_keyboard == rhs.is_one_time_keyboard &&
+         lhs.keyboard == rhs.keyboard;
+}
+
+bool operator!=(const ReplyMarkup &lhs, const ReplyMarkup &rhs) {
+  return !(lhs == rhs);
+}
+
+StringBuilder &ReplyMarkup::print(StringBuilder &string_builder) const {
+  string_builder << "ReplyMarkup[";
+  switch (type) {
+    case ReplyMarkup::Type::InlineKeyboard:
+      string_builder << "InlineKeyboard";
+      break;
+    case ReplyMarkup::Type::ShowKeyboard:
+      string_builder << "ShowKeyboard";
+      break;
+    case ReplyMarkup::Type::RemoveKeyboard:
+      string_builder << "RemoveKeyboard";
+      break;
+    case ReplyMarkup::Type::ForceReply:
+      string_builder << "ForceReply";
+      break;
+    default:
+      UNREACHABLE();
+  }
+  if (is_personal) {
+    string_builder << ", personal";
+  }
+
+  if (type == ReplyMarkup::Type::ShowKeyboard) {
+    if (need_resize_keyboard) {
+      string_builder << ", need resize";
+    }
+    if (is_one_time_keyboard) {
+      string_builder << ", one time";
+    }
+  }
+  if (type == ReplyMarkup::Type::InlineKeyboard) {
+    for (auto &row : inline_keyboard) {
+      string_builder << ", " << format::as_array(row);
+    }
+  }
+  if (type == ReplyMarkup::Type::ShowKeyboard) {
+    for (auto &row : keyboard) {
+      string_builder << ", " << format::as_array(row);
+    }
+  }
+
+  string_builder << "]";
+  return string_builder;
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const ReplyMarkup &reply_markup) {
+  return reply_markup.print(string_builder);
+}
+
+static KeyboardButton get_keyboard_button(tl_object_ptr<telegram_api::KeyboardButton> &&keyboard_button_ptr) {
+  CHECK(keyboard_button_ptr != nullptr);
+
+  KeyboardButton button;
+  switch (keyboard_button_ptr->get_id()) {
+    case telegram_api::keyboardButton::ID: {
+      auto keyboard_button = move_tl_object_as<telegram_api::keyboardButton>(keyboard_button_ptr);
+      button.type = KeyboardButton::Type::Text;
+      button.text = std::move(keyboard_button->text_);
+      break;
+    }
+    case telegram_api::keyboardButtonRequestPhone::ID: {
+      auto keyboard_button = move_tl_object_as<telegram_api::keyboardButtonRequestPhone>(keyboard_button_ptr);
+      button.type = KeyboardButton::Type::RequestPhoneNumber;
+      button.text = std::move(keyboard_button->text_);
+      break;
+    }
+    case telegram_api::keyboardButtonRequestGeoLocation::ID: {
+      auto keyboard_button = move_tl_object_as<telegram_api::keyboardButtonRequestGeoLocation>(keyboard_button_ptr);
+      button.type = KeyboardButton::Type::RequestLocation;
+      button.text = std::move(keyboard_button->text_);
+      break;
+    }
+    default:
+      LOG(ERROR) << "Unsupported keyboard button: " << to_string(keyboard_button_ptr);
+  }
+  return button;
+}
+
+static InlineKeyboardButton get_inline_keyboard_button(
+    tl_object_ptr<telegram_api::KeyboardButton> &&keyboard_button_ptr) {
+  CHECK(keyboard_button_ptr != nullptr);
+
+  InlineKeyboardButton button;
+  switch (keyboard_button_ptr->get_id()) {
+    case telegram_api::keyboardButtonUrl::ID: {
+      auto keyboard_button = move_tl_object_as<telegram_api::keyboardButtonUrl>(keyboard_button_ptr);
+      button.type = InlineKeyboardButton::Type::Url;
+      button.text = std::move(keyboard_button->text_);
+      button.data = std::move(keyboard_button->url_);
+      break;
+    }
+    case telegram_api::keyboardButtonCallback::ID: {
+      auto keyboard_button = move_tl_object_as<telegram_api::keyboardButtonCallback>(keyboard_button_ptr);
+      button.type = InlineKeyboardButton::Type::Callback;
+      button.text = std::move(keyboard_button->text_);
+      button.data = keyboard_button->data_.as_slice().str();
+      break;
+    }
+    case telegram_api::keyboardButtonGame::ID: {
+      auto keyboard_button = move_tl_object_as<telegram_api::keyboardButtonGame>(keyboard_button_ptr);
+      button.type = InlineKeyboardButton::Type::CallbackGame;
+      button.text = std::move(keyboard_button->text_);
+      break;
+    }
+    case telegram_api::keyboardButtonSwitchInline::ID: {
+      auto keyboard_button = move_tl_object_as<telegram_api::keyboardButtonSwitchInline>(keyboard_button_ptr);
+      button.type = (keyboard_button->flags_ & telegram_api::keyboardButtonSwitchInline::SAME_PEER_MASK) != 0
+                        ? InlineKeyboardButton::Type::SwitchInlineCurrentDialog
+                        : InlineKeyboardButton::Type::SwitchInline;
+      button.text = std::move(keyboard_button->text_);
+      button.data = std::move(keyboard_button->query_);
+      break;
+    }
+    case telegram_api::keyboardButtonBuy::ID: {
+      auto keyboard_button = move_tl_object_as<telegram_api::keyboardButtonBuy>(keyboard_button_ptr);
+      button.type = InlineKeyboardButton::Type::Buy;
+      button.text = std::move(keyboard_button->text_);
+      break;
+    }
+    default:
+      LOG(ERROR) << "Unsupported inline keyboard button: " << to_string(keyboard_button_ptr);
+  }
+  return button;
+}
+
+unique_ptr<ReplyMarkup> get_reply_markup(tl_object_ptr<telegram_api::ReplyMarkup> &&reply_markup_ptr, bool is_bot,
+                                         bool only_inline_keyboard, bool message_contains_mention) {
+  if (reply_markup_ptr == nullptr) {
+    return nullptr;
+  }
+
+  auto reply_markup = make_unique<ReplyMarkup>();
+  auto constructor_id = reply_markup_ptr->get_id();
+  if (only_inline_keyboard && constructor_id != telegram_api::replyInlineMarkup::ID) {
+    LOG(ERROR) << "Inline keyboard expected";
+    return nullptr;
+  }
+  switch (constructor_id) {
+    case telegram_api::replyInlineMarkup::ID: {
+      auto inline_markup = move_tl_object_as<telegram_api::replyInlineMarkup>(reply_markup_ptr);
+      reply_markup->type = ReplyMarkup::Type::InlineKeyboard;
+      reply_markup->inline_keyboard.reserve(inline_markup->rows_.size());
+      for (auto &row : inline_markup->rows_) {
+        vector<InlineKeyboardButton> buttons;
+        buttons.reserve(row->buttons_.size());
+        for (auto &button : row->buttons_) {
+          buttons.push_back(get_inline_keyboard_button(std::move(button)));
+          if (buttons.back().text.empty()) {
+            buttons.pop_back();
+          }
+        }
+        if (!buttons.empty()) {
+          reply_markup->inline_keyboard.push_back(std::move(buttons));
+        }
+      }
+      if (reply_markup->inline_keyboard.empty()) {
+        return nullptr;
+      }
+      break;
+    }
+    case telegram_api::replyKeyboardMarkup::ID: {
+      auto keyboard_markup = move_tl_object_as<telegram_api::replyKeyboardMarkup>(reply_markup_ptr);
+      reply_markup->type = ReplyMarkup::Type::ShowKeyboard;
+      reply_markup->need_resize_keyboard = (keyboard_markup->flags_ & REPLY_MARKUP_FLAG_NEED_RESIZE_KEYBOARD) != 0;
+      reply_markup->is_one_time_keyboard = (keyboard_markup->flags_ & REPLY_MARKUP_FLAG_IS_ONE_TIME_KEYBOARD) != 0;
+      reply_markup->is_personal = (keyboard_markup->flags_ & REPLY_MARKUP_FLAG_IS_PERSONAL) != 0;
+      reply_markup->keyboard.reserve(keyboard_markup->rows_.size());
+      for (auto &row : keyboard_markup->rows_) {
+        vector<KeyboardButton> buttons;
+        buttons.reserve(row->buttons_.size());
+        for (auto &button : row->buttons_) {
+          buttons.push_back(get_keyboard_button(std::move(button)));
+          if (buttons.back().text.empty()) {
+            buttons.pop_back();
+          }
+        }
+        if (!buttons.empty()) {
+          reply_markup->keyboard.push_back(std::move(buttons));
+        }
+      }
+      if (reply_markup->keyboard.empty()) {
+        return nullptr;
+      }
+      break;
+    }
+    case telegram_api::replyKeyboardHide::ID: {
+      auto hide_keyboard_markup = move_tl_object_as<telegram_api::replyKeyboardHide>(reply_markup_ptr);
+      reply_markup->type = ReplyMarkup::Type::RemoveKeyboard;
+      reply_markup->is_personal = (hide_keyboard_markup->flags_ & REPLY_MARKUP_FLAG_IS_PERSONAL) != 0;
+      break;
+    }
+    case telegram_api::replyKeyboardForceReply::ID: {
+      auto force_reply_markup = move_tl_object_as<telegram_api::replyKeyboardForceReply>(reply_markup_ptr);
+      reply_markup->type = ReplyMarkup::Type::ForceReply;
+      reply_markup->is_personal = (force_reply_markup->flags_ & REPLY_MARKUP_FLAG_IS_PERSONAL) != 0;
+      break;
+    }
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+
+  if (!is_bot && reply_markup->type != ReplyMarkup::Type::InlineKeyboard) {
+    // incoming keyboard
+    if (reply_markup->is_personal) {
+      reply_markup->is_personal = message_contains_mention;
+    } else {
+      reply_markup->is_personal = true;
+    }
+  }
+
+  return reply_markup;
+}
+
+static Result<KeyboardButton> get_keyboard_button(tl_object_ptr<td_api::keyboardButton> &&button,
+                                                  bool request_buttons_allowed) {
+  CHECK(button != nullptr);
+
+  if (!clean_input_string(button->text_)) {
+    return Status::Error(400, "Keyboard button text must be encoded in UTF-8");
+  }
+
+  KeyboardButton current_button;
+  current_button.text = std::move(button->text_);
+
+  int32 button_type_id = button->type_ == nullptr ? td_api::keyboardButtonTypeText::ID : button->type_->get_id();
+  switch (button_type_id) {
+    case td_api::keyboardButtonTypeText::ID:
+      current_button.type = KeyboardButton::Type::Text;
+      break;
+    case td_api::keyboardButtonTypeRequestPhoneNumber::ID:
+      if (!request_buttons_allowed) {
+        return Status::Error(400, "Phone number can be requested in a private chats only");
+      }
+      current_button.type = KeyboardButton::Type::RequestPhoneNumber;
+      break;
+    case td_api::keyboardButtonTypeRequestLocation::ID:
+      if (!request_buttons_allowed) {
+        return Status::Error(400, "Location can be requested in a private chats only");
+      }
+      current_button.type = KeyboardButton::Type::RequestLocation;
+      break;
+    default:
+      UNREACHABLE();
+  }
+  return current_button;
+}
+
+static Result<InlineKeyboardButton> get_inline_keyboard_button(tl_object_ptr<td_api::inlineKeyboardButton> &&button,
+                                                               bool switch_inline_current_chat_buttons_allowed) {
+  CHECK(button != nullptr);
+  if (!clean_input_string(button->text_)) {
+    return Status::Error(400, "Keyboard button text must be encoded in UTF-8");
+  }
+
+  InlineKeyboardButton current_button;
+  current_button.text = std::move(button->text_);
+
+  if (button->type_ == nullptr) {
+    return Status::Error(400, "Inline keyboard button type can't be empty");
+  }
+
+  int32 button_type_id = button->type_->get_id();
+  switch (button_type_id) {
+    case td_api::inlineKeyboardButtonTypeUrl::ID: {
+      current_button.type = InlineKeyboardButton::Type::Url;
+      TRY_RESULT(http_url, parse_url(static_cast<td_api::inlineKeyboardButtonTypeUrl *>(button->type_.get())->url_));
+      current_button.data = http_url.get_url();
+      if (!clean_input_string(current_button.data)) {
+        return Status::Error(400, "Inline keyboard button url must be encoded in UTF-8");
+      }
+      break;
+    }
+    case td_api::inlineKeyboardButtonTypeCallback::ID:
+      current_button.type = InlineKeyboardButton::Type::Callback;
+      current_button.data =
+          std::move(static_cast<td_api::inlineKeyboardButtonTypeCallback *>(button->type_.get())->data_);
+      break;
+    case td_api::inlineKeyboardButtonTypeCallbackGame::ID:
+      current_button.type = InlineKeyboardButton::Type::CallbackGame;
+      break;
+    case td_api::inlineKeyboardButtonTypeSwitchInline::ID: {
+      auto switch_inline_button = move_tl_object_as<td_api::inlineKeyboardButtonTypeSwitchInline>(button->type_);
+      if (!switch_inline_current_chat_buttons_allowed && switch_inline_button->in_current_chat_) {
+        return Status::Error(400, "Can't use switch_inline_query_current_chat in a channel chat");
+      }
+
+      current_button.type = switch_inline_button->in_current_chat_
+                                ? InlineKeyboardButton::Type::SwitchInlineCurrentDialog
+                                : InlineKeyboardButton::Type::SwitchInline;
+      current_button.data = std::move(switch_inline_button->query_);
+      if (!clean_input_string(current_button.data)) {
+        return Status::Error(400, "Inline keyboard button switch inline query must be encoded in UTF-8");
+      }
+      break;
+    }
+    case td_api::inlineKeyboardButtonTypeBuy::ID:
+      current_button.type = InlineKeyboardButton::Type::Buy;
+      break;
+    default:
+      UNREACHABLE();
+  }
+
+  return current_button;
+}
+
+Result<unique_ptr<ReplyMarkup>> get_reply_markup(tl_object_ptr<td_api::ReplyMarkup> &&reply_markup_ptr, bool is_bot,
+                                                 bool only_inline_keyboard, bool request_buttons_allowed,
+                                                 bool switch_inline_current_chat_buttons_allowed) {
+  CHECK(!only_inline_keyboard || !request_buttons_allowed);
+  if (reply_markup_ptr == nullptr || !is_bot) {
+    return nullptr;
+  }
+
+  auto reply_markup = make_unique<ReplyMarkup>();
+  auto constructor_id = reply_markup_ptr->get_id();
+  if (only_inline_keyboard && constructor_id != td_api::replyMarkupInlineKeyboard::ID) {
+    return Status::Error(400, "Inline keyboard expected");
+  }
+
+  switch (constructor_id) {
+    case td_api::replyMarkupShowKeyboard::ID: {
+      auto show_keyboard_markup = move_tl_object_as<td_api::replyMarkupShowKeyboard>(reply_markup_ptr);
+      reply_markup->type = ReplyMarkup::Type::ShowKeyboard;
+      reply_markup->need_resize_keyboard = show_keyboard_markup->resize_keyboard_;
+      reply_markup->is_one_time_keyboard = show_keyboard_markup->one_time_;
+      reply_markup->is_personal = show_keyboard_markup->is_personal_;
+
+      reply_markup->keyboard.reserve(show_keyboard_markup->rows_.size());
+      int32 total_button_count = 0;
+      for (auto &row : show_keyboard_markup->rows_) {
+        vector<KeyboardButton> row_buttons;
+        row_buttons.reserve(row.size());
+
+        int32 row_button_count = 0;
+        for (auto &button : row) {
+          if (button->text_.empty()) {
+            continue;
+          }
+
+          TRY_RESULT(current_button, get_keyboard_button(std::move(button), request_buttons_allowed));
+
+          row_buttons.push_back(std::move(current_button));
+          row_button_count++;
+          total_button_count++;
+          if (row_button_count >= 12 || total_button_count >= 300) {
+            break;
+          }
+        }
+        if (!row_buttons.empty()) {
+          reply_markup->keyboard.push_back(row_buttons);
+        }
+        if (total_button_count >= 300) {
+          break;
+        }
+      }
+      if (reply_markup->keyboard.empty()) {
+        return nullptr;
+      }
+      break;
+    }
+    case td_api::replyMarkupInlineKeyboard::ID: {
+      auto inline_keyboard_markup = move_tl_object_as<td_api::replyMarkupInlineKeyboard>(reply_markup_ptr);
+      reply_markup->type = ReplyMarkup::Type::InlineKeyboard;
+
+      reply_markup->inline_keyboard.reserve(inline_keyboard_markup->rows_.size());
+      int32 total_button_count = 0;
+      for (auto &row : inline_keyboard_markup->rows_) {
+        vector<InlineKeyboardButton> row_buttons;
+        row_buttons.reserve(row.size());
+
+        int32 row_button_count = 0;
+        for (auto &button : row) {
+          if (button->text_.empty()) {
+            continue;
+          }
+
+          TRY_RESULT(current_button,
+                     get_inline_keyboard_button(std::move(button), switch_inline_current_chat_buttons_allowed));
+
+          row_buttons.push_back(std::move(current_button));
+          row_button_count++;
+          total_button_count++;
+          if (row_button_count >= 12 || total_button_count >= 300) {
+            break;
+          }
+        }
+        if (!row_buttons.empty()) {
+          reply_markup->inline_keyboard.push_back(row_buttons);
+        }
+        if (total_button_count >= 300) {
+          break;
+        }
+      }
+      if (reply_markup->inline_keyboard.empty()) {
+        return nullptr;
+      }
+      break;
+    }
+    case td_api::replyMarkupRemoveKeyboard::ID: {
+      auto remove_keyboard_markup = move_tl_object_as<td_api::replyMarkupRemoveKeyboard>(reply_markup_ptr);
+      reply_markup->type = ReplyMarkup::Type::RemoveKeyboard;
+      reply_markup->is_personal = remove_keyboard_markup->is_personal_;
+      break;
+    }
+    case td_api::replyMarkupForceReply::ID: {
+      auto force_reply_markup = move_tl_object_as<td_api::replyMarkupForceReply>(reply_markup_ptr);
+      reply_markup->type = ReplyMarkup::Type::ForceReply;
+      reply_markup->is_personal = force_reply_markup->is_personal_;
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+
+  return std::move(reply_markup);
+}
+
+static tl_object_ptr<telegram_api::KeyboardButton> get_keyboard_button(const KeyboardButton &keyboard_button) {
+  switch (keyboard_button.type) {
+    case KeyboardButton::Type::Text:
+      return make_tl_object<telegram_api::keyboardButton>(keyboard_button.text);
+    case KeyboardButton::Type::RequestPhoneNumber:
+      return make_tl_object<telegram_api::keyboardButtonRequestPhone>(keyboard_button.text);
+    case KeyboardButton::Type::RequestLocation:
+      return make_tl_object<telegram_api::keyboardButtonRequestGeoLocation>(keyboard_button.text);
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+static tl_object_ptr<telegram_api::KeyboardButton> get_inline_keyboard_button(
+    const InlineKeyboardButton &keyboard_button) {
+  switch (keyboard_button.type) {
+    case InlineKeyboardButton::Type::Url:
+      return make_tl_object<telegram_api::keyboardButtonUrl>(keyboard_button.text, keyboard_button.data);
+    case InlineKeyboardButton::Type::Callback:
+      return make_tl_object<telegram_api::keyboardButtonCallback>(keyboard_button.text,
+                                                                  BufferSlice(keyboard_button.data));
+    case InlineKeyboardButton::Type::CallbackGame:
+      return make_tl_object<telegram_api::keyboardButtonGame>(keyboard_button.text);
+    case InlineKeyboardButton::Type::SwitchInline:
+    case InlineKeyboardButton::Type::SwitchInlineCurrentDialog: {
+      int32 flags = 0;
+      if (keyboard_button.type == InlineKeyboardButton::Type::SwitchInlineCurrentDialog) {
+        flags |= telegram_api::keyboardButtonSwitchInline::SAME_PEER_MASK;
+      }
+      return make_tl_object<telegram_api::keyboardButtonSwitchInline>(flags, false /*ignored*/, keyboard_button.text,
+                                                                      keyboard_button.data);
+    }
+    case InlineKeyboardButton::Type::Buy:
+      return make_tl_object<telegram_api::keyboardButtonBuy>(keyboard_button.text);
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+tl_object_ptr<telegram_api::ReplyMarkup> ReplyMarkup::get_input_reply_markup() const {
+  LOG(DEBUG) << "Send " << *this;
+  switch (type) {
+    case ReplyMarkup::Type::InlineKeyboard: {
+      vector<tl_object_ptr<telegram_api::keyboardButtonRow>> rows;
+      rows.reserve(inline_keyboard.size());
+      for (auto &row : inline_keyboard) {
+        vector<tl_object_ptr<telegram_api::KeyboardButton>> buttons;
+        buttons.reserve(row.size());
+        for (auto &button : row) {
+          buttons.push_back(get_inline_keyboard_button(button));
+        }
+        rows.push_back(make_tl_object<telegram_api::keyboardButtonRow>(std::move(buttons)));
+      }
+      LOG(DEBUG) << "Return inlineKeyboardMarkup to send it";
+      return make_tl_object<telegram_api::replyInlineMarkup>(std::move(rows));
+    }
+    case ReplyMarkup::Type::ShowKeyboard: {
+      vector<tl_object_ptr<telegram_api::keyboardButtonRow>> rows;
+      rows.reserve(keyboard.size());
+      for (auto &row : keyboard) {
+        vector<tl_object_ptr<telegram_api::KeyboardButton>> buttons;
+        buttons.reserve(row.size());
+        for (auto &button : row) {
+          buttons.push_back(get_keyboard_button(button));
+        }
+        rows.push_back(make_tl_object<telegram_api::keyboardButtonRow>(std::move(buttons)));
+      }
+      LOG(DEBUG) << "Return replyKeyboardMarkup to send it";
+      return make_tl_object<telegram_api::replyKeyboardMarkup>(
+          need_resize_keyboard * REPLY_MARKUP_FLAG_NEED_RESIZE_KEYBOARD +
+              is_one_time_keyboard * REPLY_MARKUP_FLAG_IS_ONE_TIME_KEYBOARD +
+              is_personal * REPLY_MARKUP_FLAG_IS_PERSONAL,
+          false /*ignored*/, false /*ignored*/, false /*ignored*/, std::move(rows));
+    }
+    case ReplyMarkup::Type::ForceReply:
+      LOG(DEBUG) << "Return replyKeyboardForceReply to send it";
+      return make_tl_object<telegram_api::replyKeyboardForceReply>(is_personal * REPLY_MARKUP_FLAG_IS_PERSONAL,
+                                                                   false /*ignored*/, false /*ignored*/);
+    case ReplyMarkup::Type::RemoveKeyboard:
+      LOG(DEBUG) << "Return replyKeyboardHide to send it";
+      return make_tl_object<telegram_api::replyKeyboardHide>(is_personal * REPLY_MARKUP_FLAG_IS_PERSONAL,
+                                                             false /*ignored*/);
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+static tl_object_ptr<td_api::keyboardButton> get_keyboard_button_object(const KeyboardButton &keyboard_button) {
+  tl_object_ptr<td_api::KeyboardButtonType> type;
+  switch (keyboard_button.type) {
+    case KeyboardButton::Type::Text:
+      type = make_tl_object<td_api::keyboardButtonTypeText>();
+      break;
+    case KeyboardButton::Type::RequestPhoneNumber:
+      type = make_tl_object<td_api::keyboardButtonTypeRequestPhoneNumber>();
+      break;
+    case KeyboardButton::Type::RequestLocation:
+      type = make_tl_object<td_api::keyboardButtonTypeRequestLocation>();
+      break;
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+  return make_tl_object<td_api::keyboardButton>(keyboard_button.text, std::move(type));
+}
+
+static tl_object_ptr<td_api::inlineKeyboardButton> get_inline_keyboard_button_object(
+    const InlineKeyboardButton &keyboard_button) {
+  tl_object_ptr<td_api::InlineKeyboardButtonType> type;
+  switch (keyboard_button.type) {
+    case InlineKeyboardButton::Type::Url:
+      type = make_tl_object<td_api::inlineKeyboardButtonTypeUrl>(keyboard_button.data);
+      break;
+    case InlineKeyboardButton::Type::Callback:
+      type = make_tl_object<td_api::inlineKeyboardButtonTypeCallback>(keyboard_button.data);
+      break;
+    case InlineKeyboardButton::Type::CallbackGame:
+      type = make_tl_object<td_api::inlineKeyboardButtonTypeCallbackGame>();
+      break;
+    case InlineKeyboardButton::Type::SwitchInline:
+      type = make_tl_object<td_api::inlineKeyboardButtonTypeSwitchInline>(keyboard_button.data, false);
+      break;
+    case InlineKeyboardButton::Type::SwitchInlineCurrentDialog:
+      type = make_tl_object<td_api::inlineKeyboardButtonTypeSwitchInline>(keyboard_button.data, true);
+      break;
+    case InlineKeyboardButton::Type::Buy:
+      type = make_tl_object<td_api::inlineKeyboardButtonTypeBuy>();
+      break;
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+  return make_tl_object<td_api::inlineKeyboardButton>(keyboard_button.text, std::move(type));
+}
+
+tl_object_ptr<td_api::ReplyMarkup> ReplyMarkup::get_reply_markup_object() const {
+  switch (type) {
+    case ReplyMarkup::Type::InlineKeyboard: {
+      vector<vector<tl_object_ptr<td_api::inlineKeyboardButton>>> rows;
+      rows.reserve(inline_keyboard.size());
+      for (auto &row : inline_keyboard) {
+        vector<tl_object_ptr<td_api::inlineKeyboardButton>> buttons;
+        buttons.reserve(row.size());
+        for (auto &button : row) {
+          buttons.push_back(get_inline_keyboard_button_object(button));
+        }
+        rows.push_back(std::move(buttons));
+      }
+
+      return make_tl_object<td_api::replyMarkupInlineKeyboard>(std::move(rows));
+    }
+    case ReplyMarkup::Type::ShowKeyboard: {
+      vector<vector<tl_object_ptr<td_api::keyboardButton>>> rows;
+      rows.reserve(keyboard.size());
+      for (auto &row : keyboard) {
+        vector<tl_object_ptr<td_api::keyboardButton>> buttons;
+        buttons.reserve(row.size());
+        for (auto &button : row) {
+          buttons.push_back(get_keyboard_button_object(button));
+        }
+        rows.push_back(std::move(buttons));
+      }
+
+      return make_tl_object<td_api::replyMarkupShowKeyboard>(std::move(rows), need_resize_keyboard,
+                                                             is_one_time_keyboard, is_personal);
+    }
+    case ReplyMarkup::Type::RemoveKeyboard:
+      return make_tl_object<td_api::replyMarkupRemoveKeyboard>(is_personal);
+    case ReplyMarkup::Type::ForceReply:
+      return make_tl_object<td_api::replyMarkupForceReply>(is_personal);
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+tl_object_ptr<telegram_api::ReplyMarkup> get_input_reply_markup(const unique_ptr<ReplyMarkup> &reply_markup) {
+  if (reply_markup == nullptr) {
+    return nullptr;
+  }
+
+  return reply_markup->get_input_reply_markup();
+}
+
+tl_object_ptr<td_api::ReplyMarkup> get_reply_markup_object(const unique_ptr<ReplyMarkup> &reply_markup) {
+  if (reply_markup == nullptr) {
+    return nullptr;
+  }
+
+  return reply_markup->get_reply_markup_object();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/ReplyMarkup.h b/libs/tdlib/td/td/telegram/ReplyMarkup.h
new file mode 100644
index 0000000000..c1ac9849ce
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/ReplyMarkup.h
@@ -0,0 +1,69 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+
+namespace td {
+
+struct KeyboardButton {
+  // append only
+  enum class Type : int32 { Text, RequestPhoneNumber, RequestLocation };
+  Type type;
+  string text;
+};
+
+struct InlineKeyboardButton {
+  // append only
+  enum class Type : int32 { Url, Callback, CallbackGame, SwitchInline, SwitchInlineCurrentDialog, Buy };
+  Type type;
+  string text;
+  string data;
+};
+
+struct ReplyMarkup {
+  // append only
+  enum class Type : int32 { InlineKeyboard, ShowKeyboard, RemoveKeyboard, ForceReply };
+  Type type;
+
+  bool is_personal = false;  // for ShowKeyboard, RemoveKeyboard, ForceReply
+
+  bool need_resize_keyboard = false;        // for ShowKeyboard
+  bool is_one_time_keyboard = false;        // for ShowKeyboard
+  vector<vector<KeyboardButton>> keyboard;  // for ShowKeyboard
+
+  vector<vector<InlineKeyboardButton>> inline_keyboard;  // for InlineKeyboard
+
+  StringBuilder &print(StringBuilder &string_builder) const;
+
+  tl_object_ptr<telegram_api::ReplyMarkup> get_input_reply_markup() const;
+
+  tl_object_ptr<td_api::ReplyMarkup> get_reply_markup_object() const;
+};
+
+bool operator==(const ReplyMarkup &lhs, const ReplyMarkup &rhs);
+bool operator!=(const ReplyMarkup &lhs, const ReplyMarkup &rhs);
+
+StringBuilder &operator<<(StringBuilder &string_builder, const ReplyMarkup &reply_markup);
+
+unique_ptr<ReplyMarkup> get_reply_markup(tl_object_ptr<telegram_api::ReplyMarkup> &&reply_markup_ptr, bool is_bot,
+                                         bool only_inline_keyboard, bool message_contains_mention);
+
+Result<unique_ptr<ReplyMarkup>> get_reply_markup(tl_object_ptr<td_api::ReplyMarkup> &&reply_markup_ptr, bool is_bot,
+                                                 bool only_inline_keyboard, bool request_buttons_allowed,
+                                                 bool switch_inline_current_chat_buttons_allowed) TD_WARN_UNUSED_RESULT;
+
+tl_object_ptr<telegram_api::ReplyMarkup> get_input_reply_markup(const unique_ptr<ReplyMarkup> &reply_markup);
+
+tl_object_ptr<td_api::ReplyMarkup> get_reply_markup_object(const unique_ptr<ReplyMarkup> &reply_markup);
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/ReplyMarkup.hpp b/libs/tdlib/td/td/telegram/ReplyMarkup.hpp
new file mode 100644
index 0000000000..4b8bf15ba5
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/ReplyMarkup.hpp
@@ -0,0 +1,81 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/ReplyMarkup.h"
+
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+
+template <class StorerT>
+void store(KeyboardButton button, StorerT &storer) {
+  store(button.type, storer);
+  store(button.text, storer);
+}
+
+template <class ParserT>
+void parse(KeyboardButton &button, ParserT &parser) {
+  parse(button.type, parser);
+  parse(button.text, parser);
+}
+
+template <class StorerT>
+void store(InlineKeyboardButton button, StorerT &storer) {
+  store(button.type, storer);
+  store(button.text, storer);
+  store(button.data, storer);
+}
+
+template <class ParserT>
+void parse(InlineKeyboardButton &button, ParserT &parser) {
+  parse(button.type, parser);
+  parse(button.text, parser);
+  parse(button.data, parser);
+}
+
+template <class StorerT>
+void store(const ReplyMarkup &reply_markup, StorerT &storer) {
+  bool has_keyboard = !reply_markup.keyboard.empty();
+  bool has_inline_keyboard = !reply_markup.inline_keyboard.empty();
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(reply_markup.is_personal);
+  STORE_FLAG(reply_markup.need_resize_keyboard);
+  STORE_FLAG(reply_markup.is_one_time_keyboard);
+  STORE_FLAG(has_keyboard);
+  STORE_FLAG(has_inline_keyboard);
+  END_STORE_FLAGS();
+  store(reply_markup.type, storer);
+  if (has_keyboard) {
+    store(reply_markup.keyboard, storer);
+  }
+  if (has_inline_keyboard) {
+    store(reply_markup.inline_keyboard, storer);
+  }
+}
+
+template <class ParserT>
+void parse(ReplyMarkup &reply_markup, ParserT &parser) {
+  bool has_keyboard = !reply_markup.keyboard.empty();
+  bool has_inline_keyboard = !reply_markup.inline_keyboard.empty();
+  BEGIN_PARSE_FLAGS();
+  PARSE_FLAG(reply_markup.is_personal);
+  PARSE_FLAG(reply_markup.need_resize_keyboard);
+  PARSE_FLAG(reply_markup.is_one_time_keyboard);
+  PARSE_FLAG(has_keyboard);
+  PARSE_FLAG(has_inline_keyboard);
+  END_PARSE_FLAGS();
+  parse(reply_markup.type, parser);
+  if (has_keyboard) {
+    parse(reply_markup.keyboard, parser);
+  }
+  if (has_inline_keyboard) {
+    parse(reply_markup.inline_keyboard, parser);
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/SecretChatActor.cpp b/libs/tdlib/td/td/telegram/SecretChatActor.cpp
new file mode 100644
index 0000000000..11688cb1d3
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/SecretChatActor.cpp
@@ -0,0 +1,2218 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/SecretChatActor.h"
+
+#include "td/mtproto/PacketStorer.h"
+
+#include "td/telegram/net/NetQueryCreator.h"
+#include "td/telegram/SecretChatId.h"
+#include "td/telegram/UniqueId.h"
+
+#include "td/telegram/secret_api.hpp"
+#include "td/telegram/telegram_api.hpp"
+
+#include "td/db/binlog/BinlogHelper.h"
+
+#include "td/actor/MultiPromise.h"
+
+#include "td/utils/crypto.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/overloaded.h"
+#include "td/utils/Random.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Time.h"
+#include "td/utils/tl_parsers.h"
+
+#include <array>
+#include <tuple>
+#include <type_traits>
+
+#define G GLOBAL_SHOULD_NOT_BE_USED_HERE
+
+namespace td {
+inline TLObjectStorer<secret_api::Object> create_storer(const secret_api::Object &object) {
+  return TLObjectStorer<secret_api::Object>(object);
+}
+class SecretImpl {
+ public:
+  explicit SecretImpl(const Storer &data) : data(data) {
+  }
+  template <class T>
+  void do_store(T &storer) const {
+    storer.store_binary(static_cast<int32>(data.size()));
+    storer.store_storer(data);
+  }
+
+ private:
+  const Storer &data;
+};
+SecretChatActor::SecretChatActor(int32 id, std::unique_ptr<Context> context, bool can_be_empty)
+    : context_(std::move(context)), can_be_empty_(can_be_empty) {
+  auth_state_.id = id;
+}
+
+void SecretChatActor::update_chat(telegram_api::object_ptr<telegram_api::EncryptedChat> chat) {
+  if (close_flag_) {
+    return;
+  }
+  check_status(on_update_chat(std::move(chat)));
+  loop();
+}
+
+void SecretChatActor::create_chat(int32 user_id, int64 user_access_hash, int32 random_id,
+                                  Promise<SecretChatId> promise) {
+  if (close_flag_) {
+    promise.set_error(Status::Error(400, "Chat is closed"));
+    return;
+  }
+  if (auth_state_.state != State::Empty) {
+    promise.set_error(Status::Error(500, "Bad random_id"));
+    check_status(Status::Error("Unexpected request_chat"));
+    loop();
+    return;
+  }
+
+  auto event = std::make_unique<logevent::CreateSecretChat>();
+  event->user_id = user_id;
+  event->user_access_hash = user_access_hash;
+  event->random_id = random_id;
+  event->set_logevent_id(
+      BinlogHelper::add(context_->binlog(), LogEvent::HandlerType::SecretChats, create_storer(*event)));
+  do_create_chat_impl(std::move(event));
+  promise.set_value(SecretChatId(random_id));
+  loop();
+}
+void SecretChatActor::on_result_resendable(NetQueryPtr net_query, Promise<NetQueryPtr> promise) {
+  LOG(INFO) << "on_result_resendable: " << net_query;
+  auto key = UniqueId::extract_key(net_query->id());
+  if (close_flag_) {
+    if (key == static_cast<uint8>(QueryType::DiscardEncryption)) {
+      on_discard_encryption_result(std::move(net_query));
+    }
+    return;
+  }
+  check_status([&] {
+    switch (key) {
+      case static_cast<uint8>(QueryType::DhConfig):
+        return on_dh_config(std::move(net_query));
+      case static_cast<uint8>(QueryType::EncryptedChat):
+        return on_update_chat(std::move(net_query));
+      case static_cast<uint8>(QueryType::Message):
+        return on_outbound_send_message_result(std::move(net_query), std::move(promise)), Status::OK();
+      case static_cast<uint8>(QueryType::Ignore):
+        return Status::OK();
+    }
+    UNREACHABLE();
+  }());
+
+  loop();
+}
+void SecretChatActor::replay_close_chat(std::unique_ptr<logevent::CloseSecretChat> event) {
+  if (close_flag_) {
+    return;
+  }
+  do_close_chat_impl(std::move(event));
+}
+void SecretChatActor::replay_create_chat(std::unique_ptr<logevent::CreateSecretChat> event) {
+  if (close_flag_) {
+    return;
+  }
+  do_create_chat_impl(std::move(event));
+}
+void SecretChatActor::add_inbound_message(std::unique_ptr<logevent::InboundSecretMessage> message) {
+  SCOPE_EXIT {
+    if (message) {
+      message->qts_ack.set_value(Unit());
+    }
+  };
+  if (close_flag_) {
+    return;
+  }
+  if (auth_state_.state != State::Ready) {
+    LOG(ERROR) << "Ignore unexpected update: " << tag("message", *message);
+    return;
+  }
+  check_status(do_inbound_message_encrypted(std::move(message)));
+  loop();
+}
+
+void SecretChatActor::replay_inbound_message(std::unique_ptr<logevent::InboundSecretMessage> message) {
+  if (close_flag_) {
+    return;
+  }
+  if (auth_state_.state != State::Ready) {
+    LOG(ERROR) << "Ignore unexpected replay inbound message: " << tag("message", *message);
+    return;
+  }
+
+  CHECK(!binlog_replay_finish_flag_);
+  CHECK(message->decrypted_message_layer);  // from binlog
+  if (message->is_pending) {                // wait for gaps?
+    // check_status(do_inbound_message_decrypted_unchecked(std::move(message)));
+    do_inbound_message_decrypted_pending(std::move(message));
+  } else {  // just replay
+    CHECK(message->message_id > last_binlog_message_id_)
+        << tag("last_binlog_message_id", last_binlog_message_id_) << tag("message_id", message->message_id);
+    last_binlog_message_id_ = message->message_id;
+    check_status(do_inbound_message_decrypted(std::move(message)));
+  }
+  loop();
+}
+
+void SecretChatActor::replay_outbound_message(std::unique_ptr<logevent::OutboundSecretMessage> message) {
+  if (close_flag_) {
+    return;
+  }
+  if (auth_state_.state != State::Ready) {
+    LOG(ERROR) << "Ignore unexpected replay outbound message: " << tag("message", *message);
+    return;
+  }
+  CHECK(!binlog_replay_finish_flag_);
+  CHECK(message->message_id > last_binlog_message_id_)
+      << tag("last_binlog_message_id", last_binlog_message_id_) << tag("message_id", message->message_id);
+  last_binlog_message_id_ = message->message_id;
+  do_outbound_message_impl(std::move(message), Promise<>());
+  loop();
+}
+
+// NB: my_seq_no is just after message is sent, i.e. my_out_seq_no is already incremented
+Result<BufferSlice> SecretChatActor::create_encrypted_message(int32 layer, int32 my_in_seq_no, int32 my_out_seq_no,
+                                                              tl_object_ptr<secret_api::DecryptedMessage> &message) {
+  if (message->get_id() == secret_api::decryptedMessage::ID && layer < MTPROTO_2_LAYER) {
+    auto old = secret_api::move_object_as<secret_api::decryptedMessage>(message);
+    old->flags_ &= ~secret_api::decryptedMessage::GROUPED_ID_MASK;
+    message = secret_api::make_object<secret_api::decryptedMessage46>(
+        old->flags_, old->random_id_, old->ttl_, std::move(old->message_), std::move(old->media_),
+        std::move(old->entities_), std::move(old->via_bot_name_), old->reply_to_random_id_);
+  }
+
+  mtproto::AuthKey *auth_key = &pfs_state_.auth_key;
+  auto in_seq_no = my_in_seq_no * 2 + auth_state_.x;
+  auto out_seq_no = my_out_seq_no * 2 - 1 - auth_state_.x;
+
+  BufferSlice random_bytes(32);
+  Random::secure_bytes(random_bytes.as_slice().ubegin(), random_bytes.size());
+  auto message_with_layer = secret_api::make_object<secret_api::decryptedMessageLayer>(
+      std::move(random_bytes), layer, in_seq_no, out_seq_no, std::move(message));
+  LOG(INFO) << to_string(message_with_layer);
+  auto storer = create_storer(*message_with_layer);
+  auto new_storer = mtproto::PacketStorer<SecretImpl>(storer);
+  mtproto::PacketInfo info;
+  info.type = mtproto::PacketInfo::EndToEnd;
+  // Send with mtproto 2.0 if current layer is at least MTPROTO_2_LAYER
+  info.version = layer >= MTPROTO_2_LAYER ? 2 : 1;
+  info.is_creator = auth_state_.x == 0;
+  auto packet_writer = BufferWriter{mtproto::Transport::write(new_storer, *auth_key, &info), 0, 0};
+  mtproto::Transport::write(new_storer, *auth_key, &info, packet_writer.as_slice());
+  message = std::move(message_with_layer->message_);
+  return packet_writer.as_buffer_slice();
+}
+
+void SecretChatActor::send_message(tl_object_ptr<secret_api::DecryptedMessage> message,
+                                   tl_object_ptr<telegram_api::InputEncryptedFile> file, Promise<> promise) {
+  if (close_flag_) {
+    promise.set_error(Status::Error(400, "Chat is closed"));
+    return;
+  }
+  send_message_impl(std::move(message), std::move(file), SendFlag::External | SendFlag::Push, std::move(promise));
+}
+
+static int32 get_min_layer(const secret_api::decryptedMessageActionTyping &message) {
+  switch (message.action_->get_id()) {
+    case secret_api::sendMessageRecordRoundAction::ID:
+    case secret_api::sendMessageUploadRoundAction::ID:
+      return SecretChatActor::VOICE_NOTES_LAYER;
+  }
+  return 0;
+}
+static int32 get_min_layer(const secret_api::decryptedMessageService &message) {
+  switch (message.action_->get_id()) {
+    case secret_api::decryptedMessageActionTyping::ID:
+      return get_min_layer(static_cast<const secret_api::decryptedMessageActionTyping &>(*message.action_));
+    default:
+      return 0;
+  }
+}
+static int32 get_min_layer(const secret_api::DocumentAttribute &attribute) {
+  switch (attribute.get_id()) {
+    case secret_api::documentAttributeVideo66::ID:
+      return SecretChatActor::VOICE_NOTES_LAYER;
+    default:
+      return 0;
+  }
+}
+static int32 get_min_layer(const secret_api::decryptedMessageMediaDocument &message) {
+  int32 res = 0;
+  for (auto &attribute : message.attributes_) {
+    auto attrirbute_layer = get_min_layer(*attribute);
+    if (attrirbute_layer > res) {
+      res = attrirbute_layer;
+    }
+    return res;
+  }
+  return res;
+}
+static int32 get_min_layer(const secret_api::decryptedMessage &message) {
+  if (!message.media_) {
+    return 0;
+  }
+  switch (message.media_->get_id()) {
+    case secret_api::decryptedMessageMediaDocument::ID:
+      return get_min_layer(static_cast<const secret_api::decryptedMessageMediaDocument &>(*message.media_));
+    default:
+      return 0;
+  }
+}
+static int32 get_min_layer(const secret_api::DecryptedMessage &message) {
+  switch (message.get_id()) {
+    case secret_api::decryptedMessageService::ID:
+      return get_min_layer(static_cast<const secret_api::decryptedMessageService &>(message));
+    case secret_api::decryptedMessage::ID:
+      return get_min_layer(static_cast<const secret_api::decryptedMessage &>(message));
+    default:
+      return 0;
+  }
+}
+
+void SecretChatActor::send_message_impl(tl_object_ptr<secret_api::DecryptedMessage> message,
+                                        tl_object_ptr<telegram_api::InputEncryptedFile> file, int32 flags,
+                                        Promise<> promise) {
+  if (close_flag_) {
+    promise.set_error(Status::Error(400, "Chat is closed"));
+    return;
+  }
+  if (auth_state_.state != State::Ready) {
+    LOG(ERROR) << "Ignore send_message: " << tag("message", to_string(message)) << tag("file", to_string(file));
+    return promise.set_error(Status::Error(400, "Chat is not accessible"));
+  }
+  if (get_min_layer(*message) > config_state_.his_layer) {
+    return promise.set_error(Status::Error(400, "Message is not supported by the other side"));
+  }
+  CHECK(binlog_replay_finish_flag_) << "Trying to send message before binlog replay is finished: "
+                                    << to_string(*message) << to_string(file);
+  int64 random_id = 0;
+  downcast_call(*message, [&](auto &x) { random_id = x.random_id_; });
+
+  LOG(INFO) << "Send message: " << to_string(*message) << to_string(file);
+
+  auto it = random_id_to_outbound_message_state_token_.find(random_id);
+  if (it != end(random_id_to_outbound_message_state_token_)) {
+    return on_outbound_outer_send_message_promise(it->second, std::move(promise));
+  }
+
+  auto binlog_event = std::make_unique<logevent::OutboundSecretMessage>();
+  binlog_event->chat_id = auth_state_.id;
+  binlog_event->random_id = random_id;
+  binlog_event->file = logevent::EncryptedInputFile::from_input_encrypted_file(file);
+  binlog_event->message_id = seq_no_state_.message_id + 1;
+  binlog_event->my_in_seq_no = seq_no_state_.my_in_seq_no;
+  binlog_event->my_out_seq_no = seq_no_state_.my_out_seq_no + 1;
+  binlog_event->his_in_seq_no = seq_no_state_.his_in_seq_no;
+  binlog_event->encrypted_message =
+      create_encrypted_message(current_layer(), binlog_event->my_in_seq_no, binlog_event->my_out_seq_no, message)
+          .move_as_ok();
+  binlog_event->is_service = (flags & SendFlag::Push) == 0;
+  binlog_event->is_external = (flags & SendFlag::External) != 0;
+  if (message->get_id() == secret_api::decryptedMessageService::ID) {
+    binlog_event->is_rewritable = false;
+    auto service_message = move_tl_object_as<secret_api::decryptedMessageService>(message);
+    binlog_event->action = std::move(service_message->action_);
+  } else {
+    binlog_event->is_rewritable = true;
+  }
+
+  do_outbound_message_impl(std::move(binlog_event), std::move(promise));
+}
+
+void SecretChatActor::send_message_action(tl_object_ptr<secret_api::SendMessageAction> action) {
+  if (close_flag_) {
+    return;
+  }
+  if (auth_state_.state != State::Ready) {
+    LOG(ERROR) << "Ignore send_message_action: " << tag("message", to_string(action));
+    return;
+  }
+  bool flag = action->get_id() != secret_api::sendMessageCancelAction::ID;
+
+  auto net_query = context_->net_query_creator().create(
+      UniqueId::next(UniqueId::Type::Default, static_cast<uint8>(QueryType::Ignore)),
+      create_storer(telegram_api::messages_setEncryptedTyping(get_input_chat(), flag)));
+  if (!set_typing_query_.empty()) {
+    LOG(INFO) << "Cancel previous set typing query";
+    cancel_query(set_typing_query_);
+  }
+  set_typing_query_ = net_query.get_weak();
+  context_->send_net_query(std::move(net_query), actor_shared(this), false);
+}
+void SecretChatActor::send_read_history(int32 date, Promise<> promise) {
+  if (close_flag_) {
+    promise.set_error(Status::Error(400, "Chat is closed"));
+    return;
+  }
+  if (auth_state_.state != State::Ready) {
+    LOG(ERROR) << "Ignore send_read_history: " << tag("date", date);
+    promise.set_error(Status::Error(400, "Can't access the chat"));
+    return;
+  }
+  // TODO: use promise
+  context_->send_net_query(context_->net_query_creator().create(
+                               UniqueId::next(UniqueId::Type::Default, static_cast<uint8>(QueryType::Ignore)),
+                               create_storer(telegram_api::messages_readEncryptedHistory(get_input_chat(), date))),
+                           actor_shared(this), false);
+}
+void SecretChatActor::send_open_message(int64 random_id, Promise<> promise) {
+  if (close_flag_) {
+    promise.set_error(Status::Error(400, "Chat is closed"));
+    return;
+  }
+  if (auth_state_.state != State::Ready) {
+    promise.set_error(Status::Error(400, "Can't access the chat"));
+    return;
+  }
+  std::vector<int64> random_ids{random_id};
+  send_action(make_tl_object<secret_api::decryptedMessageActionReadMessages>(std::move(random_ids)), SendFlag::Push,
+              std::move(promise));
+}
+
+void SecretChatActor::delete_message(int64 random_id, Promise<> promise) {
+  if (close_flag_) {
+    promise.set_error(Status::Error(400, "Chat is closed"));
+    return;
+  }
+  if (auth_state_.state != State::Ready) {
+    promise.set_error(Status::Error(400, "Can't access the chat"));
+    return;
+  }
+  return delete_messages(std::vector<int64>{random_id}, std::move(promise));
+}
+
+void SecretChatActor::delete_messages(std::vector<int64> random_ids, Promise<> promise) {
+  if (close_flag_) {
+    promise.set_error(Status::Error(400, "Chat is closed"));
+    return;
+  }
+  if (auth_state_.state != State::Ready) {
+    promise.set_error(Status::Error(400, "Can't access the chat"));
+    return;
+  }
+  send_action(make_tl_object<secret_api::decryptedMessageActionDeleteMessages>(std::move(random_ids)), SendFlag::Push,
+              std::move(promise));
+}
+void SecretChatActor::delete_all_messages(Promise<> promise) {
+  if (close_flag_) {
+    promise.set_error(Status::Error(400, "Chat is closed"));
+    return;
+  }
+  if (auth_state_.state != State::Ready) {
+    promise.set_error(Status::Error(400, "Can't access the chat"));
+    return;
+  }
+  send_action(make_tl_object<secret_api::decryptedMessageActionFlushHistory>(), SendFlag::Push, std::move(promise));
+}
+
+void SecretChatActor::notify_screenshot_taken(Promise<> promise) {
+  if (close_flag_) {
+    promise.set_error(Status::Error(400, "Chat is closed"));
+    return;
+  }
+  if (auth_state_.state != State::Ready) {
+    promise.set_error(Status::Error(400, "Can't access the chat"));
+    return;
+  }
+  send_action(make_tl_object<secret_api::decryptedMessageActionScreenshotMessages>(), SendFlag::Push,
+              std::move(promise));
+}
+
+void SecretChatActor::send_set_ttl_message(int32 ttl, int64 random_id, Promise<> promise) {
+  if (close_flag_) {
+    promise.set_error(Status::Error(400, "Chat is closed"));
+    return;
+  }
+  if (auth_state_.state != State::Ready) {
+    promise.set_error(Status::Error(400, "Can't access the chat"));
+    return;
+  }
+  send_message_impl(secret_api::make_object<secret_api::decryptedMessageService>(
+                        random_id, make_tl_object<secret_api::decryptedMessageActionSetMessageTTL>(ttl)),
+                    nullptr, SendFlag::External | SendFlag::Push, std::move(promise));
+}
+
+void SecretChatActor::send_action(tl_object_ptr<secret_api::DecryptedMessageAction> action, int32 flags,
+                                  Promise<> promise) {
+  send_message_impl(
+      secret_api::make_object<secret_api::decryptedMessageService>(Random::secure_int64(), std::move(action)), nullptr,
+      flags, std::move(promise));
+}
+
+void SecretChatActor::binlog_replay_finish() {
+  on_his_in_seq_no_updated();
+  LOG(INFO) << "Binlog replay is finished";
+  LOG(INFO) << "binlog_replay_finish with SeqNoState=" << seq_no_state_;
+  LOG(INFO) << "binlog_replay_finish with PfsState=" << pfs_state_;
+  binlog_replay_finish_flag_ = true;
+  if (auth_state_.state == State::Ready) {
+    if (config_state_.my_layer < MY_LAYER) {
+      send_action(secret_api::make_object<secret_api::decryptedMessageActionNotifyLayer>(MY_LAYER), SendFlag::None,
+                  Promise<>());
+    }
+  }
+  yield();
+}
+
+void SecretChatActor::loop() {
+  if (close_flag_) {
+    return;
+  }
+  if (!binlog_replay_finish_flag_) {
+    return;
+  }
+
+  check_status(do_loop());
+}
+
+Status SecretChatActor::do_loop() {
+  TRY_STATUS(run_auth());
+  run_pfs();
+  run_fill_gaps();
+  return Status::OK();
+}
+
+void SecretChatActor::on_send_message_ack(int64 random_id) {
+  context_->on_send_message_ack(random_id);
+}
+
+Status SecretChatActor::on_delete_messages(const std::vector<int64> &random_ids) {
+  for (auto random_id : random_ids) {
+    auto it = random_id_to_outbound_message_state_token_.find(random_id);
+    if (it == random_id_to_outbound_message_state_token_.end()) {
+      continue;
+    }
+    auto state_id = it->second;
+    TRY_STATUS(outbound_rewrite_with_empty(state_id));
+  }
+  return Status::OK();
+}
+
+Status SecretChatActor::on_flush_history(int32 last_message_id) {
+  std::vector<uint64> to_rewrite;
+  outbound_message_states_.for_each([&](auto state_id, auto &state) {
+    if (state.message->message_id < last_message_id && state.message->is_rewritable) {
+      to_rewrite.push_back(state_id);
+    }
+  });
+  for (auto state_id : to_rewrite) {
+    TRY_STATUS(outbound_rewrite_with_empty(state_id));
+  }
+  return Status::OK();
+}
+
+Status SecretChatActor::run_auth() {
+  switch (auth_state_.state) {
+    case State::Empty:
+      return Status::OK();
+    case State::SendRequest: {
+      if (!auth_state_.handshake.has_config()) {
+        return Status::OK();
+      }
+      // messages.requestEncryption#f64daf43 user_id:InputUser random_id:int g_a:bytes = EncryptedChat;
+      telegram_api::messages_requestEncryption tl_query;
+      tl_query.user_id_ = get_input_user();
+      tl_query.random_id_ = auth_state_.random_id;
+      tl_query.g_a_ = BufferSlice(auth_state_.handshake.get_g_b());
+      auto query = context_->net_query_creator().create(
+          UniqueId::next(UniqueId::Type::Default, static_cast<uint8>(QueryType::EncryptedChat)),
+          create_storer(tl_query));
+      context_->send_net_query(std::move(query), actor_shared(this), false);
+      auth_state_.state = State::WaitRequestResponse;
+      return Status::OK();
+    }
+    case State::SendAccept: {
+      if (!auth_state_.handshake.has_config()) {
+        return Status::OK();
+      }
+      TRY_STATUS(auth_state_.handshake.run_checks(context_->dh_callback()));
+      auto id_and_key = auth_state_.handshake.gen_key();
+      pfs_state_.auth_key = mtproto::AuthKey(id_and_key.first, std::move(id_and_key.second));
+      calc_key_hash();
+      // messages.acceptEncryption#3dbc0415 peer:InputEncryptedChat g_b:bytes key_fingerprint:long =
+      // EncryptedChat;
+      telegram_api::messages_acceptEncryption tl_query;
+      tl_query.peer_ = get_input_chat();
+      tl_query.g_b_ = BufferSlice(auth_state_.handshake.get_g_b());
+      tl_query.key_fingerprint_ = pfs_state_.auth_key.id();
+      auto query = context_->net_query_creator().create(
+          UniqueId::next(UniqueId::Type::Default, static_cast<uint8>(QueryType::EncryptedChat)),
+          create_storer(tl_query));
+      context_->send_net_query(std::move(query), actor_shared(this), false);
+      auth_state_.state = State::WaitAcceptResponse;
+      return Status::OK();
+    }
+    default:
+      break;
+  }
+  return Status::OK();
+}
+
+void SecretChatActor::run_fill_gaps() {
+  // replay messages
+  while (true) {
+    if (pending_inbound_messages_.empty()) {
+      break;
+    }
+    auto begin = pending_inbound_messages_.begin();
+    auto next_seq_no = begin->first;
+    if (next_seq_no <= seq_no_state_.my_in_seq_no) {
+      LOG(INFO) << "Replay pending event: " << tag("seq_no", next_seq_no);
+      auto message = std::move(begin->second);
+      pending_inbound_messages_.erase(begin);
+      check_status(do_inbound_message_decrypted_unchecked(std::move(message)));
+      CHECK(pending_inbound_messages_.find(next_seq_no) == pending_inbound_messages_.end());
+    } else {
+      break;
+    }
+  }
+
+  if (pending_inbound_messages_.empty()) {
+    return;
+  }
+
+  auto start_seq_no = seq_no_state_.my_in_seq_no;
+  auto finish_seq_no = pending_inbound_messages_.begin()->first - 1;
+  LOG(INFO) << tag("start_seq_no", start_seq_no) << tag("finish_seq_no", finish_seq_no)
+            << tag("resend_end_seq_no", seq_no_state_.resend_end_seq_no);
+  CHECK(start_seq_no <= finish_seq_no);
+  if (seq_no_state_.resend_end_seq_no >= finish_seq_no) {
+    return;
+  }
+  CHECK(seq_no_state_.resend_end_seq_no < start_seq_no);
+
+  start_seq_no = start_seq_no * 2 + auth_state_.x;
+  finish_seq_no = finish_seq_no * 2 + auth_state_.x;
+
+  send_action(secret_api::make_object<secret_api::decryptedMessageActionResend>(start_seq_no, finish_seq_no),
+              SendFlag::None, Promise<>());
+}
+
+void SecretChatActor::run_pfs() {
+  while (true) {
+    LOG(INFO) << "Run pfs loop: " << pfs_state_;
+    if (pfs_state_.state == PfsState::Empty &&
+        (pfs_state_.last_message_id + 100 < seq_no_state_.message_id ||
+         pfs_state_.last_timestamp + 60 * 60 * 24 * 7 < Time::now()) &&
+        pfs_state_.other_auth_key.empty()) {
+      LOG(INFO) << "Request new key";
+      request_new_key();
+    }
+    switch (pfs_state_.state) {
+      case PfsState::SendRequest: {
+        // shouldn't wait, pfs_state is already saved explicitly
+        pfs_state_.state = PfsState::WaitSendRequest;  // don't save it!
+        send_action(secret_api::make_object<secret_api::decryptedMessageActionRequestKey>(
+                        pfs_state_.exchange_id, BufferSlice(pfs_state_.handshake.get_g_b())),
+                    SendFlag::None, Promise<>());
+        break;
+      }
+      case PfsState::SendCommit: {
+        // must wait till pfs_state is saved to binlog. Otherwise we may save ActionCommit to binlog without pfs_state,
+        // which has the new auth_key.
+        if (saved_pfs_state_message_id_ < pfs_state_.wait_message_id) {
+          return;
+        }
+
+        // TODO: wait till gaps are filled???
+        pfs_state_.state = PfsState::WaitSendCommit;  // don't save it
+        send_action(secret_api::make_object<secret_api::decryptedMessageActionCommitKey>(
+                        pfs_state_.exchange_id, static_cast<int64>(pfs_state_.other_auth_key.id())),
+                    SendFlag::None, Promise<>());
+
+        break;
+      }
+      case PfsState::SendAccept: {
+        if (saved_pfs_state_message_id_ < pfs_state_.wait_message_id) {
+          return;
+        }
+
+        pfs_state_.state = PfsState::WaitSendAccept;  // don't save it
+        send_action(secret_api::make_object<secret_api::decryptedMessageActionAcceptKey>(
+                        pfs_state_.exchange_id, BufferSlice(pfs_state_.handshake.get_g_b()),
+                        static_cast<int64>(pfs_state_.other_auth_key.id())),
+                    SendFlag::None, Promise<>());
+
+        break;
+      }
+      default:
+        return;
+    }
+  }
+}
+
+void SecretChatActor::check_status(Status status) {
+  if (status.is_error()) {
+    if (status.code() == 1) {
+      LOG(WARNING) << "Non-fatal error: " << status;
+    } else {
+      on_fatal_error(std::move(status));
+    }
+  }
+}
+
+void SecretChatActor::on_fatal_error(Status status) {
+  LOG(ERROR) << "Fatal error: " << status;
+  cancel_chat(Promise<>());
+}
+
+void SecretChatActor::cancel_chat(Promise<> promise) {
+  if (close_flag_) {
+    promise.set_error(Status::Error(400, "Chat is already closing"));
+    return;
+  }
+  close_flag_ = true;
+
+  std::vector<logevent::LogEvent::Id> to_delete;
+  outbound_message_states_.for_each(
+      [&](auto state_id, auto &state) { to_delete.push_back(state.message->logevent_id()); });
+  inbound_message_states_.for_each([&](auto state_id, auto &state) { to_delete.push_back(state.logevent_id); });
+
+  // TODO: It must be a transaction
+  for (auto id : to_delete) {
+    BinlogHelper::erase(context_->binlog(), id);
+  }
+  if (create_logevent_id_ != 0) {
+    BinlogHelper::erase(context_->binlog(), create_logevent_id_);
+    create_logevent_id_ = 0;
+  }
+
+  auto event = std::make_unique<logevent::CloseSecretChat>();
+  event->chat_id = auth_state_.id;
+  event->set_logevent_id(
+      BinlogHelper::add(context_->binlog(), LogEvent::HandlerType::SecretChats, create_storer(*event)));
+
+  auto on_sync = PromiseCreator::lambda(
+      [actor_id = actor_id(this), event = std::move(event), promise = std::move(promise)](Result<Unit> result) mutable {
+        if (result.is_ok()) {
+          send_closure(actor_id, &SecretChatActor::do_close_chat_impl, std::move(event));
+          promise.set_value(Unit());
+        } else {
+          promise.set_error(result.error().clone());
+          send_closure(actor_id, &SecretChatActor::on_promise_error, result.move_as_error(), "do_close_chat_impl");
+        }
+      });
+
+  context_->binlog()->force_sync(std::move(on_sync));
+  yield();
+}
+
+void SecretChatActor::do_close_chat_impl(std::unique_ptr<logevent::CloseSecretChat> event) {
+  close_flag_ = true;
+  close_logevent_id_ = event->logevent_id();
+  LOG(INFO) << "Send messages.discardEncryption";
+  context_->secret_chat_db()->erase_value(auth_state_);
+  context_->secret_chat_db()->erase_value(config_state_);
+  context_->secret_chat_db()->erase_value(pfs_state_);
+  context_->secret_chat_db()->erase_value(seq_no_state_);
+  telegram_api::messages_discardEncryption tl_query(auth_state_.id);
+  auto query = context_->net_query_creator().create(
+      UniqueId::next(UniqueId::Type::Default, static_cast<uint8>(QueryType::DiscardEncryption)),
+      create_storer(tl_query));
+
+  auth_state_.state = State::Closed;
+  send_update_secret_chat();
+
+  context_->send_net_query(std::move(query), actor_shared(this), true);
+}
+
+void SecretChatActor::do_create_chat_impl(std::unique_ptr<logevent::CreateSecretChat> event) {
+  LOG(INFO) << *event;
+  CHECK(event->random_id == auth_state_.id);
+  create_logevent_id_ = event->logevent_id();
+
+  if (auth_state_.state == State::Empty) {
+    auth_state_.user_id = event->user_id;
+    auth_state_.user_access_hash = event->user_access_hash;
+    auth_state_.random_id = event->random_id;
+    auth_state_.state = State::SendRequest;
+    auth_state_.x = 0;
+    auth_state_.date = context_->unix_time();
+    send_update_secret_chat();
+  } else if (auth_state_.state == State::SendRequest) {
+  } else if (auth_state_.state == State::WaitRequestResponse) {
+  } else {
+    BinlogHelper::erase(context_->binlog(), create_logevent_id_);
+    create_logevent_id_ = 0;
+  }
+}
+void SecretChatActor::on_discard_encryption_result(NetQueryPtr result) {
+  CHECK(close_flag_);
+  LOG(INFO) << "Got result for messages.discardEncryption";
+  BinlogHelper::erase(context_->binlog(), close_logevent_id_);
+  // skip flush
+  stop();
+}
+
+telegram_api::object_ptr<telegram_api::inputUser> SecretChatActor::get_input_user() {
+  return telegram_api::make_object<telegram_api::inputUser>(auth_state_.user_id, auth_state_.user_access_hash);
+}
+telegram_api::object_ptr<telegram_api::inputEncryptedChat> SecretChatActor::get_input_chat() {
+  return telegram_api::make_object<telegram_api::inputEncryptedChat>(auth_state_.id, auth_state_.access_hash);
+}
+void SecretChatActor::tear_down() {
+  LOG(INFO) << "SecretChatActor: tear_down";
+  // TODO notify send update that we are dead
+}
+
+Result<std::tuple<uint64, BufferSlice, int32>> SecretChatActor::decrypt(BufferSlice &encrypted_message) {
+  MutableSlice data = encrypted_message.as_slice();
+  CHECK(is_aligned_pointer<4>(data.data()));
+  TRY_RESULT(auth_key_id, mtproto::Transport::read_auth_key_id(data));
+  mtproto::AuthKey *auth_key = nullptr;
+  if (auth_key_id == pfs_state_.auth_key.id()) {
+    auth_key = &pfs_state_.auth_key;
+  } else if (auth_key_id == pfs_state_.other_auth_key.id()) {
+    auth_key = &pfs_state_.other_auth_key;
+  } else {
+    return Status::Error(1, PSLICE() << "Unknown " << tag("auth_key_id", format::as_hex(auth_key_id))
+                                     << tag("crc", crc64(encrypted_message.as_slice())));
+  }
+
+  // expect that message is encrypted with mtproto 2.0 if his layer is at least MTPROTO_2_LAYER
+  std::array<int, 2> versions{{1, 2}};
+  if (config_state_.his_layer >= MTPROTO_2_LAYER) {
+    std::swap(versions[0], versions[1]);
+  }
+
+  BufferSlice encrypted_message_copy;
+  int32 mtproto_version = -1;
+  int32 error_code = 0;
+  for (size_t i = 0; i < versions.size(); i++) {
+    bool is_last = i + 1 == versions.size();
+    encrypted_message_copy = encrypted_message.copy();
+    data = encrypted_message_copy.as_slice();
+    CHECK(is_aligned_pointer<4>(data.data()));
+
+    mtproto::PacketInfo info;
+    info.type = mtproto::PacketInfo::EndToEnd;
+    mtproto_version = versions[i];
+    info.version = mtproto_version;
+    info.is_creator = auth_state_.x == 0;
+    auto status = mtproto::Transport::read(data, *auth_key, &info, &data, &error_code);
+    if (is_last) {
+      TRY_STATUS(std::move(status));
+    } else if (status.is_error()) {
+      LOG(WARNING) << tag("mtproto", mtproto_version) << " decryption failed " << status;
+      continue;
+    }
+    break;
+  }
+
+  if (error_code) {
+    return Status::Error(PSLICE() << "Got mtproto error code: " << error_code);
+  }
+  auto len = as<int32>(data.begin());
+  data = data.substr(4, len);
+  if (!is_aligned_pointer<4>(data.data())) {
+    return std::make_tuple(auth_key_id, BufferSlice(data), mtproto_version);
+  } else {
+    return std::make_tuple(auth_key_id, encrypted_message_copy.from_slice(data), mtproto_version);
+  }
+}
+
+Status SecretChatActor::do_inbound_message_encrypted(std::unique_ptr<logevent::InboundSecretMessage> message) {
+  SCOPE_EXIT {
+    if (message) {
+      message->qts_ack.set_value(Unit());
+    }
+  };
+  TRY_RESULT(decrypted, decrypt(message->encrypted_message));
+  auto auth_key_id = std::get<0>(decrypted);
+  auto data_buffer = std::move(std::get<1>(decrypted));
+  auto mtproto_version = std::get<2>(decrypted);
+  message->auth_key_id = auth_key_id;
+
+  TlBufferParser parser(&data_buffer);
+  auto id = parser.fetch_int();
+  Status status;
+  if (id == secret_api::decryptedMessageLayer::ID) {
+    auto message_with_layer = secret_api::decryptedMessageLayer::fetch(parser);
+    if (!parser.get_error()) {
+      auto layer = message_with_layer->layer_;
+      if (layer < DEFAULT_LAYER && false /*TODO: fix android app bug? */) {
+        LOG(ERROR) << "All or nothing, " << tag("layer", layer) << " is not supported, drop message "
+                   << to_string(message_with_layer);
+        return Status::OK();
+      }
+      if (config_state_.his_layer < layer) {
+        config_state_.his_layer = layer;
+        context_->secret_chat_db()->set_value(config_state_);
+        send_update_secret_chat();
+      }
+      if (layer >= MTPROTO_2_LAYER && mtproto_version < 2) {
+        return Status::Error(PSLICE() << "Mtproto 1.0 encryption is forbidden for this layer");
+      }
+      if (message_with_layer->in_seq_no_ < 0) {
+        return Status::Error(PSLICE() << "Invalid seq_no: " << to_string(message_with_layer));
+      }
+      message->decrypted_message_layer = std::move(message_with_layer);
+      return do_inbound_message_decrypted_unchecked(std::move(message));
+    } else {
+      status = Status::Error(PSLICE() << parser.get_error() << format::as_hex_dump<4>(data_buffer.as_slice()));
+    }
+  } else {
+    status = Status::Error(PSLICE() << "Unknown constructor " << tag("ID", format::as_hex(id)));
+  }
+
+  // support for older layer
+  LOG(WARNING) << "Failed to Fetch update: " << status;
+  send_action(secret_api::make_object<secret_api::decryptedMessageActionNotifyLayer>(MY_LAYER), SendFlag::None,
+              Promise<>());
+
+  if (config_state_.his_layer == 8) {
+    TlBufferParser new_parser(&data_buffer);
+    auto message_without_layer = secret_api::DecryptedMessage::fetch(new_parser);
+    if (!new_parser.get_error()) {
+      message->decrypted_message_layer = secret_api::make_object<secret_api::decryptedMessageLayer>(
+          BufferSlice(), config_state_.his_layer, -1, -1, std::move(message_without_layer));
+      return do_inbound_message_decrypted_unchecked(std::move(message));
+    }
+    LOG(ERROR) << "Failed to fetch update (DecryptedMessage): " << new_parser.get_error()
+               << format::as_hex_dump<4>(data_buffer.as_slice());
+  }
+
+  return status;
+}
+
+Status SecretChatActor::check_seq_no(int in_seq_no, int out_seq_no) {
+  if (in_seq_no < 0) {
+    return Status::OK();
+  }
+  if (in_seq_no % 2 != (1 - auth_state_.x) || out_seq_no % 2 != auth_state_.x) {
+    return Status::Error("Bad seq_no parity");
+  }
+  in_seq_no /= 2;
+  out_seq_no /= 2;
+  if (out_seq_no < seq_no_state_.my_in_seq_no) {
+    return Status::Error(1, "Old seq_no");
+  }
+  if (out_seq_no > seq_no_state_.my_in_seq_no) {
+    return Status::Error(2, "Gap found!");
+  }
+  if (in_seq_no < seq_no_state_.his_in_seq_no) {
+    return Status::Error("in_seq_no is not monotonic");
+  }
+  if (seq_no_state_.my_out_seq_no < in_seq_no) {
+    return Status::Error("in_seq_no is bigger than seq_no_state_.my_out_seq_no");
+  }
+
+  return Status::OK();
+}
+
+Status SecretChatActor::do_inbound_message_decrypted_unchecked(
+    std::unique_ptr<logevent::InboundSecretMessage> message) {
+  SCOPE_EXIT {
+    LOG_IF(FATAL, message && message->qts_ack) << "Lost qts_promise";
+  };
+  auto in_seq_no = message->decrypted_message_layer->in_seq_no_;
+  auto out_seq_no = message->decrypted_message_layer->out_seq_no_;
+  auto status = check_seq_no(in_seq_no, out_seq_no);
+  if (status.is_error() && status.code() != 2 /* not gap found */) {
+    message->qts_ack.set_value(Unit());
+    if (message->logevent_id()) {
+      LOG(INFO) << "Erase binlog event: " << tag("logevent_id", message->logevent_id());
+      BinlogHelper::erase(context_->binlog(), message->logevent_id());
+    }
+    auto warning_message = PSTRING() << status << tag("seq_no_state_.my_in_seq_no", seq_no_state_.my_in_seq_no)
+                                     << tag("seq_no_state_.my_out_seq_no", seq_no_state_.my_out_seq_no)
+                                     << tag("seq_no_state_.his_in_seq_no", seq_no_state_.his_in_seq_no)
+                                     << tag("in_seq_no", in_seq_no) << tag("out_seq_no", out_seq_no)
+                                     << to_string(message->decrypted_message_layer);
+    if (status.code()) {
+      LOG(WARNING) << warning_message;
+    } else {
+      LOG(ERROR) << warning_message;
+    }
+    return status;
+  }
+
+  // Process ActionResend.
+  if (message->decrypted_message_layer->message_->get_id() == secret_api::decryptedMessageService::ID) {
+    auto *decrypted_message_service =
+        static_cast<secret_api::decryptedMessageService *>(message->decrypted_message_layer->message_.get());
+    if (decrypted_message_service->action_->get_id() == secret_api::decryptedMessageActionResend::ID) {
+      auto *action_resend =
+          static_cast<secret_api::decryptedMessageActionResend *>(decrypted_message_service->action_.get());
+
+      uint32 start_seq_no = static_cast<uint32>(action_resend->start_seq_no_ / 2);
+      uint32 finish_seq_no = static_cast<uint32>(action_resend->end_seq_no_ / 2);
+      if (start_seq_no + MAX_RESEND_COUNT < finish_seq_no) {
+        message->qts_ack.set_value(Unit());
+        return Status::Error(PSLICE() << "Won't resend more than " << MAX_RESEND_COUNT << " messages");
+      }
+      LOG(INFO) << "ActionResend: " << tag("start", start_seq_no) << tag("finish_seq_no", finish_seq_no);
+      for (auto seq_no = start_seq_no; seq_no <= finish_seq_no; seq_no++) {
+        auto it = out_seq_no_to_outbound_message_state_token_.find(seq_no);
+        if (it == out_seq_no_to_outbound_message_state_token_.end()) {
+          message->qts_ack.set_value(Unit());
+          return Status::Error(PSLICE() << "Can't resend query " << tag("seq_no", seq_no));
+        }
+        auto state_id = it->second;
+        outbound_resend(state_id);
+      }
+      // It is ok to replace action with Noop, because it won't be written to binlog before message is marked unsent
+      decrypted_message_service->action_ = secret_api::make_object<secret_api::decryptedMessageActionNoop>();
+    }
+  }
+
+  LOG(INFO) << "GOT MESSAGE " << to_string(message->decrypted_message_layer);
+
+  if (status.is_error()) {
+    CHECK(status.code() == 2);  // gap found
+    do_inbound_message_decrypted_pending(std::move(message));
+    return Status::OK();
+  }
+
+  message->message_id = seq_no_state_.message_id + 1;
+  if (in_seq_no != -1) {
+    message->my_in_seq_no = out_seq_no / 2 + 1;
+    message->my_out_seq_no = seq_no_state_.my_out_seq_no;
+    message->his_in_seq_no = in_seq_no / 2;
+  }
+
+  return do_inbound_message_decrypted(std::move(message));
+}
+
+void SecretChatActor::do_outbound_message_impl(std::unique_ptr<logevent::OutboundSecretMessage> binlog_event,
+                                               Promise<> promise) {
+  binlog_event->crc = crc64(binlog_event->encrypted_message.as_slice());
+  LOG(INFO) << "Do outbound message: " << *binlog_event << tag("crc", binlog_event->crc);
+  auto &state_id_ref = random_id_to_outbound_message_state_token_[binlog_event->random_id];
+  CHECK(state_id_ref == 0) << "Random id collision";
+  state_id_ref = outbound_message_states_.create();
+  const uint64 state_id = state_id_ref;
+  auto *state = outbound_message_states_.get(state_id);
+  LOG(INFO) << tag("state_id", state_id);
+  CHECK(state);
+  state->message = std::move(binlog_event);
+
+  // OutboundSecretMessage
+  //
+  // 1. [] => Save logevent. [save_logevent]
+  // 2. [save_logevent] => Save SeqNoState [save_changes]
+  // 3. [save_logevent] => Send NetQuery [send_message]
+  //   Note: we have to force binlog to flush
+  // 4.0 [send_message]:Fail => rewrite
+  // 4. [save_changes; send_message] => Mark logevent as sent [rewrite_logevent]
+  // 5. [save_changes; send_message; ack] => [remove_logevent]
+
+  auto message = state->message.get();
+
+  // send_message
+  auto send_message_start = PromiseCreator::lambda([actor_id = actor_id(this), state_id](Result<> result) {
+    if (result.is_ok()) {
+      send_closure(actor_id, &SecretChatActor::on_outbound_send_message_start, state_id);
+    } else {
+      send_closure(actor_id, &SecretChatActor::on_promise_error, result.move_as_error(),
+                   "on_oubound_send_message_start");
+    }
+  });
+
+  // update seq_no
+  update_seq_no_state(*message);
+
+  // process action
+  if (message->action) {
+    on_outbound_action(*message->action, message->message_id);
+  }
+
+  // save_changes
+  auto save_changes_finish = PromiseCreator::lambda([actor_id = actor_id(this), state_id](Result<> result) {
+    if (result.is_ok()) {
+      send_closure(actor_id, &SecretChatActor::on_outbound_save_changes_finish, state_id);
+    } else {
+      send_closure(actor_id, &SecretChatActor::on_promise_error, result.move_as_error(),
+                   "on_outbound_save_chages_finish");
+    }
+  });
+
+  auto save_changes_start = add_changes(std::move(save_changes_finish));
+
+  // wait for ack
+  auto out_seq_no = state->message->my_out_seq_no - 1;
+  if (out_seq_no < seq_no_state_.his_in_seq_no) {
+    state->ack_flag = true;
+  } else {
+    out_seq_no_to_outbound_message_state_token_[out_seq_no] = state_id;
+  }
+
+  // save_logevent => [send_message; save_changes]
+  auto save_logevent_finish = PromiseCreator::join(std::move(send_message_start), std::move(save_changes_start));
+
+  auto logevent_id = state->message->logevent_id();
+  if (logevent_id == 0) {
+    logevent_id =
+        BinlogHelper::add(context_->binlog(), LogEvent::HandlerType::SecretChats, create_storer(*state->message));
+    LOG(INFO) << "Outbound secret message [save_logevent] start " << tag("logevent_id", logevent_id);
+    context_->binlog()->force_sync(std::move(save_logevent_finish));
+    state->message->set_logevent_id(logevent_id);
+  } else {
+    LOG(INFO) << "Outbound secret message [save_logevent] skip " << tag("logevent_id", logevent_id);
+    save_logevent_finish.set_value(Unit());
+  }
+  promise.set_value(Unit());  // logevent was sent to binlog;
+}
+
+void SecretChatActor::on_his_in_seq_no_updated() {
+  auto it = begin(out_seq_no_to_outbound_message_state_token_);
+  while (it != end(out_seq_no_to_outbound_message_state_token_) && it->first < seq_no_state_.his_in_seq_no) {
+    auto token = it->second;
+    it = out_seq_no_to_outbound_message_state_token_.erase(it);
+    on_outbound_ack(token);
+  }
+}
+void SecretChatActor::on_seq_no_state_changed() {
+  seq_no_state_changed_ = true;
+}
+
+void SecretChatActor::on_pfs_state_changed() {
+  LOG(INFO) << "on_pfs_state_changed: " << pfs_state_;
+  pfs_state_changed_ = true;
+}
+Promise<> SecretChatActor::add_changes(Promise<> save_changes_finish) {
+  StateChange change;
+  if (seq_no_state_changed_) {
+    change.seq_no_state_change = SeqNoStateChange(seq_no_state_);
+    seq_no_state_changed_ = false;
+  }
+  if (pfs_state_changed_) {
+    change.pfs_state_change = PfsStateChange(pfs_state_);
+    pfs_state_changed_ = false;
+  }
+
+  change.save_changes_finish = std::move(save_changes_finish);
+  auto save_changes_start_token = changes_processor_.add(std::move(change));
+
+  return PromiseCreator::lambda([actor_id = actor_id(this), save_changes_start_token](Result<> result) {
+    if (result.is_ok()) {
+      send_closure(actor_id, &SecretChatActor::on_save_changes_start, save_changes_start_token);
+    } else {
+      send_closure(actor_id, &SecretChatActor::on_promise_error, result.move_as_error(), "on_save_changes_start");
+    }
+  });
+}
+
+template <class T>
+void SecretChatActor::update_seq_no_state(const T &new_seq_no_state) {
+  // Some old updates may arrive. Just ignore them
+  if (seq_no_state_.message_id >= new_seq_no_state.message_id &&
+      seq_no_state_.my_in_seq_no >= new_seq_no_state.my_in_seq_no &&
+      seq_no_state_.my_out_seq_no >= new_seq_no_state.my_out_seq_no &&
+      seq_no_state_.his_in_seq_no >= new_seq_no_state.his_in_seq_no) {
+    return;
+  }
+  seq_no_state_.message_id = new_seq_no_state.message_id;
+  if (new_seq_no_state.my_in_seq_no != -1) {
+    LOG(INFO) << "my_in_seq_no: " << seq_no_state_.my_in_seq_no << "--->" << new_seq_no_state.my_in_seq_no;
+    seq_no_state_.my_in_seq_no = new_seq_no_state.my_in_seq_no;
+    seq_no_state_.my_out_seq_no = new_seq_no_state.my_out_seq_no;
+
+    if (seq_no_state_.his_in_seq_no != new_seq_no_state.his_in_seq_no) {
+      seq_no_state_.his_in_seq_no = new_seq_no_state.his_in_seq_no;
+      on_his_in_seq_no_updated();
+    }
+  }
+
+  return on_seq_no_state_changed();
+}
+
+Status SecretChatActor::do_inbound_message_decrypted_pending(std::unique_ptr<logevent::InboundSecretMessage> message) {
+  // Just save logevent if necessary
+  auto logevent_id = message->logevent_id();
+
+  // qts
+  auto qts_promise = std::move(message->qts_ack);
+
+  if (logevent_id == 0) {
+    message->is_pending = true;
+    message->set_logevent_id(BinlogHelper::add(context_->binlog(), LogEvent::HandlerType::SecretChats,
+                                               create_storer(*message), std::move(qts_promise)));
+    LOG(INFO) << "Inbound PENDING secret message [save_logevent] start (do not expect finish) "
+              << tag("logevent_id", message->logevent_id());
+  } else {
+    LOG(INFO) << "Inbound PENDING secret message [save_logevent] skip " << tag("logevent_id", logevent_id);
+    CHECK(!qts_promise);
+  }
+  LOG(INFO) << "Inbound PENDING secret message start " << tag("logevent_id", logevent_id) << tag("message", *message);
+
+  auto seq_no = message->decrypted_message_layer->out_seq_no_ / 2;
+  pending_inbound_messages_[seq_no] = std::move(message);
+
+  return Status::OK();
+}
+
+Status SecretChatActor::do_inbound_message_decrypted(std::unique_ptr<logevent::InboundSecretMessage> message) {
+  // InboundSecretMessage
+  //
+  // 1. [] => Add logevent. [save_logevent]
+  // 2. [save_logevent] => Save SeqNoState [save_changes]
+  // 3. [save_logevent] => Add message to MessageManager [save_message]
+  //    Note: if we are able to add message by random_id, we may not wait for (logevent). Otherwise we should force
+  //    binlog flush.
+  // 4. [save_logevent] => Update qts [qts]
+  // 5. [save_changes; save_message; ?qts) => Remove logevent [remove_logevent]
+  //    Note: It is easier not to wait for qts. In the worst case old update will be handled again after restart.
+
+  auto state_id = inbound_message_states_.create();
+  InboundMessageState &state = *inbound_message_states_.get(state_id);
+
+  // save logevent
+  auto logevent_id = message->logevent_id();
+  bool need_sync = false;
+  if (logevent_id == 0) {
+    logevent_id = BinlogHelper::add(context_->binlog(), LogEvent::HandlerType::SecretChats, create_storer(*message));
+    LOG(INFO) << "Inbound secret message [save_logevent] start " << tag("logevent_id", logevent_id);
+    need_sync = true;
+  } else {
+    if (message->is_pending) {
+      message->is_pending = false;
+      auto old_logevent_id = logevent_id;
+      logevent_id = BinlogHelper::add(context_->binlog(), LogEvent::HandlerType::SecretChats, create_storer(*message));
+      BinlogHelper::erase(context_->binlog(), old_logevent_id);
+      LOG(INFO) << "Inbound secret message [save_logevent] rewrite (after pending state) "
+                << tag("logevent_id", logevent_id) << tag("old_logevent_id", old_logevent_id);
+      need_sync = true;
+    } else {
+      LOG(INFO) << "Inbound secret message [save_logevent] skip " << tag("logevent_id", logevent_id);
+    }
+  }
+  LOG(INFO) << "Inbound secret message start " << tag("logevent_id", logevent_id) << tag("message", *message);
+  state.logevent_id = logevent_id;
+
+  // save_message
+  auto save_message_finish = PromiseCreator::lambda([actor_id = actor_id(this), state_id](Result<> result) {
+    if (result.is_ok()) {
+      send_closure(actor_id, &SecretChatActor::on_inbound_save_message_finish, state_id);
+    } else {
+      send_closure(actor_id, &SecretChatActor::on_promise_error, result.move_as_error(),
+                   "on_inbound_save_message_finish");
+    }
+  });
+
+  // update seq_no
+  update_seq_no_state(*message);
+
+  // drop old key
+  if (!pfs_state_.other_auth_key.empty() && message->auth_key_id == pfs_state_.auth_key.id() &&
+      pfs_state_.can_forget_other_key) {
+    LOG(INFO) << "Drop old auth key " << tag("auth_key_id", format::as_hex(pfs_state_.other_auth_key.id()));
+    pfs_state_.other_auth_key = mtproto::AuthKey();
+    on_pfs_state_changed();
+  }
+
+  // qts
+  auto qts_promise = std::move(message->qts_ack);
+
+  // process message
+  tl_object_ptr<telegram_api::encryptedFile> file;
+  if (message->has_encrypted_file) {
+    file = message->file.as_encrypted_file();
+  }
+
+  if (message->decrypted_message_layer->message_->get_id() == secret_api::decryptedMessage46::ID) {
+    auto old = move_tl_object_as<secret_api::decryptedMessage46>(message->decrypted_message_layer->message_);
+    old->flags_ &= ~secret_api::decryptedMessage::GROUPED_ID_MASK;  // just in case
+    message->decrypted_message_layer->message_ = secret_api::make_object<secret_api::decryptedMessage>(
+        old->flags_, old->random_id_, old->ttl_, std::move(old->message_), std::move(old->media_),
+        std::move(old->entities_), std::move(old->via_bot_name_), old->reply_to_random_id_, 0);
+  }
+
+  // NB: message is invalid after this 'move_as'
+  // Send update through context_
+  // Note, that update may be sent multiple times and should be somehow protected from replay.
+  // Luckily all updates seems to be idempotent.
+  // We could use ChangesProcessor to mark logevent as sent to context_, but I don't see any advantages of this
+  // approach.
+  if (message->decrypted_message_layer->message_->get_id() == secret_api::decryptedMessage::ID) {
+    auto decrypted_message =
+        move_tl_object_as<secret_api::decryptedMessage>(message->decrypted_message_layer->message_);
+    context_->on_inbound_message(get_user_id(), MessageId(ServerMessageId(message->message_id)), message->date,
+                                 std::move(file), std::move(decrypted_message), std::move(save_message_finish));
+  } else if (message->decrypted_message_layer->message_->get_id() == secret_api::decryptedMessageService::ID) {
+    auto decrypted_message_service =
+        move_tl_object_as<secret_api::decryptedMessageService>(message->decrypted_message_layer->message_);
+
+    auto action = std::move(decrypted_message_service->action_);
+    switch (action->get_id()) {
+      case secret_api::decryptedMessageActionDeleteMessages::ID:
+        // Corresponding logevent won't be deleted before promise returned by add_changes is set.
+        context_->on_delete_messages(
+            std::move(static_cast<secret_api::decryptedMessageActionDeleteMessages &>(*action).random_ids_),
+            std::move(save_message_finish));
+        break;
+      case secret_api::decryptedMessageActionFlushHistory::ID:
+        context_->on_flush_history(MessageId(ServerMessageId(message->message_id)), std::move(save_message_finish));
+        break;
+      case secret_api::decryptedMessageActionReadMessages::ID: {
+        auto &random_ids = static_cast<secret_api::decryptedMessageActionReadMessages &>(*action).random_ids_;
+        if (random_ids.size() == 1) {
+          context_->on_read_message(random_ids[0], std::move(save_message_finish));
+        } else {  // probably never happens
+          MultiPromiseActorSafe mpas;
+          mpas.add_promise(std::move(save_message_finish));
+          auto lock = mpas.get_promise();
+          for (auto random_id : random_ids) {
+            context_->on_read_message(random_id, mpas.get_promise());
+          }
+          lock.set_value(Unit());
+        }
+        break;
+      }
+      case secret_api::decryptedMessageActionScreenshotMessages::ID:
+        context_->on_screenshot_taken(get_user_id(), MessageId(ServerMessageId(message->message_id)), message->date,
+                                      decrypted_message_service->random_id_, std::move(save_message_finish));
+        break;
+      case secret_api::decryptedMessageActionSetMessageTTL::ID:
+        context_->on_set_ttl(get_user_id(), MessageId(ServerMessageId(message->message_id)), message->date,
+                             static_cast<secret_api::decryptedMessageActionSetMessageTTL &>(*action).ttl_seconds_,
+                             decrypted_message_service->random_id_, std::move(save_message_finish));
+        break;
+      default:
+        /*
+decryptedMessageActionResend#511110b0 start_seq_no:int end_seq_no:int = DecryptedMessageAction;
+decryptedMessageActionNotifyLayer#f3048883 layer:int = DecryptedMessageAction;
+decryptedMessageActionTyping#ccb27641 action:SendMessageAction = DecryptedMessageAction;
+decryptedMessageActionRequestKey#f3c9611b exchange_id:long g_a:bytes = DecryptedMessageAction;
+decryptedMessageActionAcceptKey#6fe1735b exchange_id:long g_b:bytes key_fingerprint:long = DecryptedMessageAction;
+decryptedMessageActionAbortKey#dd05ec6b exchange_id:long = DecryptedMessageAction;
+decryptedMessageActionCommitKey#ec2e0b9b exchange_id:long key_fingerprint:long = DecryptedMessageAction;
+decryptedMessageActionNoop#a82fdd63 = DecryptedMessageAction;
+        */
+        save_message_finish.set_value(Unit());
+        break;
+    }
+
+    state.message_id = message->message_id;
+    TRY_STATUS(on_inbound_action(*action, message->message_id));
+  } else {
+    LOG(ERROR) << "INGORE MESSAGE: " << to_string(message->decrypted_message_layer);
+    save_message_finish.set_value(Unit());
+  }
+
+  // save_changes
+  auto save_changes_finish = PromiseCreator::lambda([actor_id = actor_id(this), state_id](Result<> result) {
+    if (result.is_ok()) {
+      send_closure(actor_id, &SecretChatActor::on_inbound_save_changes_finish, state_id);
+    } else {
+      send_closure(actor_id, &SecretChatActor::on_promise_error, result.move_as_error(),
+                   "on_inbound_save_changes_finish");
+    }
+  });
+  auto save_changes_start = add_changes(std::move(save_changes_finish));
+
+  // save_logevent
+  auto save_logevent_finish = PromiseCreator::join(std::move(save_changes_start), std::move(qts_promise));
+  if (need_sync) {
+    // TODO: lazy sync is enough
+    context_->binlog()->force_sync(std::move(save_logevent_finish));
+  } else {
+    save_logevent_finish.set_value(Unit());
+  }
+  return Status::OK();
+}
+
+void SecretChatActor::on_save_changes_start(ChangesProcessor<StateChange>::Id save_changes_token) {
+  if (close_flag_) {
+    return;
+  }
+  SeqNoStateChange seq_no_state_change;
+  PfsStateChange pfs_state_change;
+  std::vector<Promise<Unit>> save_changes_finish_promises;
+  changes_processor_.finish(save_changes_token, [&](StateChange &&change) {
+    save_changes_finish_promises.emplace_back(std::move(change.save_changes_finish));
+    if (change.seq_no_state_change) {
+      seq_no_state_change = std::move(change.seq_no_state_change);
+    }
+    if (change.pfs_state_change) {
+      pfs_state_change = std::move(change.pfs_state_change);
+    }
+  });
+  if (seq_no_state_change) {
+    LOG(INFO) << "SAVE SeqNoState " << seq_no_state_change;
+    context_->secret_chat_db()->set_value(seq_no_state_change);
+  }
+  if (pfs_state_change) {
+    LOG(INFO) << "SAVE PfsState " << pfs_state_change;
+    saved_pfs_state_message_id_ = pfs_state_change.message_id;
+    context_->secret_chat_db()->set_value(pfs_state_change);
+  }
+  // NB: we may not wait till db is flushed, because every other change will be in the same binlog
+  for (auto &save_changes_finish : save_changes_finish_promises) {
+    save_changes_finish.set_value(Unit());
+  }
+}
+
+void SecretChatActor::on_inbound_save_message_finish(uint64 state_id) {
+  if (close_flag_) {
+    return;
+  }
+  auto *state = inbound_message_states_.get(state_id);
+  CHECK(state);
+  LOG(INFO) << "Inbound message [save_message] finish " << tag("logevent_id", state->logevent_id);
+  state->save_message_finish = true;
+  inbound_loop(state, state_id);
+}
+
+void SecretChatActor::on_inbound_save_changes_finish(uint64 state_id) {
+  if (close_flag_) {
+    return;
+  }
+  auto *state = inbound_message_states_.get(state_id);
+  CHECK(state);
+  LOG(INFO) << "Inbound message [save_changes] finish " << tag("logevent_id", state->logevent_id);
+  state->save_changes_finish = true;
+  inbound_loop(state, state_id);
+}
+
+void SecretChatActor::inbound_loop(InboundMessageState *state, uint64 state_id) {
+  if (close_flag_) {
+    return;
+  }
+  if (!state->save_changes_finish || !state->save_message_finish) {
+    return;
+  }
+  LOG(INFO) << "Inbound message [remove_logevent] start " << tag("logevent_id", state->logevent_id);
+  BinlogHelper::erase(context_->binlog(), state->logevent_id);
+
+  inbound_message_states_.erase(state_id);
+}
+
+NetQueryPtr SecretChatActor::create_net_query(const logevent::OutboundSecretMessage &message) {
+  NetQueryPtr query;
+  if (message.is_service) {
+    CHECK(message.file.empty());
+    query = context_->net_query_creator().create(
+        UniqueId::next(UniqueId::Type::Default, static_cast<uint8>(QueryType::Message)),
+        create_storer(telegram_api::messages_sendEncryptedService(get_input_chat(), message.random_id,
+                                                                  message.encrypted_message.clone())));
+    query->total_timeout_limit = 1000000000;  // inf. We will re-sent it immediately anyway.
+  } else if (message.file.empty()) {
+    query = context_->net_query_creator().create(
+        UniqueId::next(UniqueId::Type::Default, static_cast<uint8>(QueryType::Message)),
+        create_storer(telegram_api::messages_sendEncrypted(get_input_chat(), message.random_id,
+                                                           message.encrypted_message.clone())));
+  } else {
+    query = context_->net_query_creator().create(
+        UniqueId::next(UniqueId::Type::Default, static_cast<uint8>(QueryType::Message)),
+        create_storer(telegram_api::messages_sendEncryptedFile(get_input_chat(), message.random_id,
+                                                               message.encrypted_message.clone(),
+                                                               message.file.as_input_encrypted_file())));
+  }
+  if (message.is_external && context_->get_config_option_boolean("use_quick_ack")) {
+    query->quick_ack_promise_ =
+        PromiseCreator::lambda([actor_id = actor_id(this), random_id = message.random_id](
+                                   Unit) { send_closure(actor_id, &SecretChatActor::on_send_message_ack, random_id); },
+                               PromiseCreator::Ignore());
+  }
+
+  return query;
+}
+
+void SecretChatActor::on_outbound_send_message_start(uint64 state_id) {
+  if (close_flag_) {
+    return;
+  }
+  auto *state = outbound_message_states_.get(state_id);
+  if (state == nullptr) {
+    LOG(INFO) << "Outbound message [send_message] start ignored (unknown state_id) " << tag("state_id", state_id);
+    return;
+  }
+
+  auto *message = state->message.get();
+
+  if (!message->is_sent) {
+    LOG(INFO) << "Outbound message [send_message] start " << tag("logevent_id", state->message->logevent_id());
+    auto query = create_net_query(*message);
+    state->net_query_id = query->id();
+    state->net_query_ref = query.get_weak();
+    state->net_query_may_fail = state->message->is_rewritable;
+    context_->send_net_query(std::move(query), actor_shared(this, state_id), true);
+  } else {
+    LOG(INFO) << "Outbound message [send_message] start dummy " << tag("logevent_id", state->message->logevent_id());
+    on_outbound_send_message_finish(state_id);
+  }
+}
+
+void SecretChatActor::outbound_resend(uint64 state_id) {
+  if (close_flag_) {
+    return;
+  }
+  auto *state = outbound_message_states_.get(state_id);
+  CHECK(state);
+
+  state->message->is_sent = false;
+  state->net_query_id = 0;
+  state->net_query_ref = NetQueryRef();
+  LOG(INFO) << "Oubound message [resend] " << tag("logevent_id", state->message->logevent_id())
+            << tag("state_id", state_id);
+
+  BinlogHelper::rewrite(context_->binlog(), state->message->logevent_id(), LogEvent::HandlerType::SecretChats,
+                        create_storer(*state->message));
+  auto send_message_start = PromiseCreator::lambda([actor_id = actor_id(this), state_id](Result<> result) {
+    if (result.is_ok()) {
+      send_closure(actor_id, &SecretChatActor::on_outbound_send_message_start, state_id);
+    } else {
+      send_closure(actor_id, &SecretChatActor::on_promise_error, result.move_as_error(),
+                   "on_outbound_send_message_start");
+    }
+  });
+  context_->binlog()->force_sync(std::move(send_message_start));
+}
+
+Status SecretChatActor::outbound_rewrite_with_empty(uint64 state_id) {
+  if (close_flag_) {
+    return Status::OK();
+  }
+  auto *state = outbound_message_states_.get(state_id);
+  if (state == nullptr || !state->message->is_rewritable) {
+    return Status::OK();
+  }
+  cancel_query(state->net_query_ref);
+
+  MutableSlice data = state->message->encrypted_message.as_slice();
+  CHECK(is_aligned_pointer<4>(data.data()));
+
+  // Rewrite with delete itself.
+  tl_object_ptr<secret_api::DecryptedMessage> message = secret_api::make_object<secret_api::decryptedMessageService>(
+      state->message->random_id, secret_api::make_object<secret_api::decryptedMessageActionDeleteMessages>(
+                                     std::vector<int64>{static_cast<int64>(state->message->random_id)}));
+
+  TRY_RESULT(encrypted_message, create_encrypted_message(current_layer(), state->message->my_in_seq_no,
+                                                         state->message->my_out_seq_no, message));
+  state->message->encrypted_message = std::move(encrypted_message);
+  LOG(INFO) << tag("crc", crc64(state->message->encrypted_message.as_slice()));
+  state->message->is_rewritable = false;
+  state->message->is_external = false;
+  state->message->is_service = true;
+  state->message->file = logevent::EncryptedInputFile::from_input_encrypted_file(nullptr);
+  BinlogHelper::rewrite(context_->binlog(), state->message->logevent_id(), LogEvent::HandlerType::SecretChats,
+                        create_storer(*state->message));
+  return Status::OK();
+}
+
+void SecretChatActor::on_outbound_send_message_result(NetQueryPtr query, Promise<NetQueryPtr> resend_promise) {
+  if (close_flag_) {
+    return;
+  }
+  auto state_id = get_link_token();
+  auto *state = outbound_message_states_.get(state_id);
+  if (!state) {
+    LOG(INFO) << "Ignore old net query result " << tag("state_id", state_id);
+    query->clear();
+    return;
+  }
+  CHECK(state);
+  if (state->net_query_id != query->id()) {
+    LOG(INFO) << "Ignore old net query result " << tag("logevent_id", state->message->logevent_id())
+              << tag("query_id", query->id()) << tag("state_query_id", state->net_query_id) << query;
+    query->clear();
+    return;
+  }
+
+  state->net_query_id = 0;
+  state->net_query_ref = NetQueryRef();
+
+  auto r_result = fetch_result<telegram_api::messages_sendEncrypted>(std::move(query));
+  if (r_result.is_error()) {
+    auto error = r_result.move_as_error();
+
+    auto send_message_error_promise =
+        PromiseCreator::lambda([actor_id = actor_id(this), state_id, error = error.clone(),
+                                resend_promise = std::move(resend_promise)](Result<> result) mutable {
+          if (result.is_ok()) {
+            send_closure(actor_id, &SecretChatActor::on_outbound_send_message_error, state_id, std::move(error),
+                         std::move(resend_promise));
+          } else {
+            send_closure(actor_id, &SecretChatActor::on_promise_error, result.move_as_error(),
+                         "on_outbound_send_message_error");
+          }
+        });
+
+    if (state->message->is_external) {
+      LOG(INFO) << "Outbound secret message [send_message] failed, rewrite it with dummy "
+                << tag("logevent_id", state->message->logevent_id()) << tag("error", error);
+      state->send_result_ = [this, random_id = state->message->random_id, error_code = error.code(),
+                             error_message = error.message()](Promise<> promise) {
+        this->context_->on_send_message_error(random_id, Status::Error(error_code, error_message), std::move(promise));
+      };
+      state->send_result_(std::move(send_message_error_promise));
+    } else {
+      // Just resend.
+      LOG(INFO) << "Outbound secret message [send_message] failed, resend it "
+                << tag("logevent_id", state->message->logevent_id()) << tag("error", error);
+      send_message_error_promise.set_value(Unit());
+    }
+    return;
+  }
+
+  auto result = r_result.move_as_ok();
+  LOG(INFO) << "Got messages_sendEncrypted result: " << tag("message_id", state->message->message_id)
+            << tag("random_id", state->message->random_id) << to_string(*result);
+
+  auto send_message_finish_promise = PromiseCreator::lambda([actor_id = actor_id(this), state_id](Result<> result) {
+    if (result.is_ok()) {
+      send_closure(actor_id, &SecretChatActor::on_outbound_send_message_finish, state_id);
+    } else {
+      send_closure(actor_id, &SecretChatActor::on_promise_error, result.move_as_error(),
+                   "on_outbound_send_message_finish");
+    }
+  });
+
+  if (state->message->is_external) {
+    switch (result->get_id()) {
+      case telegram_api::messages_sentEncryptedMessage::ID: {
+        auto sent = move_tl_object_as<telegram_api::messages_sentEncryptedMessage>(result);
+        state->send_result_ = [this, random_id = state->message->random_id,
+                               message_id = MessageId(ServerMessageId(state->message->message_id)),
+                               date = sent->date_](Promise<> promise) {
+          this->context_->on_send_message_ok(random_id, message_id, date, nullptr, std::move(promise));
+        };
+        state->send_result_(std::move(send_message_finish_promise));
+        return;
+      }
+      case telegram_api::messages_sentEncryptedFile::ID: {
+        auto sent = move_tl_object_as<telegram_api::messages_sentEncryptedFile>(result);
+        std::function<telegram_api::object_ptr<telegram_api::EncryptedFile>()> get_file;
+        telegram_api::downcast_call(
+            *sent->file_, overloaded(
+                              [&](telegram_api::encryptedFileEmpty &) {
+                                state->message->file = logevent::EncryptedInputFile::from_input_encrypted_file(
+                                    telegram_api::inputEncryptedFileEmpty());
+                                get_file = [] { return telegram_api::make_object<telegram_api::encryptedFileEmpty>(); };
+                              },
+                              [&](telegram_api::encryptedFile &file) {
+                                state->message->file = logevent::EncryptedInputFile::from_input_encrypted_file(
+                                    telegram_api::inputEncryptedFile(file.id_, file.access_hash_));
+                                get_file = [id = file.id_, access_hash = file.access_hash_, size = file.size_,
+                                            dc_id = file.dc_id_, key_fingerprint = file.key_fingerprint_] {
+                                  return telegram_api::make_object<telegram_api::encryptedFile>(id, access_hash, size,
+                                                                                                dc_id, key_fingerprint);
+                                };
+                              }));
+
+        state->send_result_ = [this, random_id = state->message->random_id,
+                               message_id = MessageId(ServerMessageId(state->message->message_id)), date = sent->date_,
+                               get_file = std::move(get_file)](Promise<> promise) {
+          this->context_->on_send_message_ok(random_id, message_id, date, get_file(), std::move(promise));
+        };
+        state->send_result_(std::move(send_message_finish_promise));
+        return;
+      }
+    }
+  }
+  send_message_finish_promise.set_value(Unit());
+}
+
+void SecretChatActor::on_outbound_send_message_error(uint64 state_id, Status error,
+                                                     Promise<NetQueryPtr> resend_promise) {
+  if (close_flag_) {
+    return;
+  }
+  auto *state = outbound_message_states_.get(state_id);
+  if (!state) {
+    return;
+  }
+  bool need_sync = false;
+  if (state->net_query_may_fail) {
+    // message could be already non-rewritable, if it was deleted during NetQuery execution.
+    if (state->message->is_rewritable) {
+      delete_message(state->message->random_id, Promise<>());
+      // state pointer may be invalidated
+      state = outbound_message_states_.get(state_id);
+      need_sync = true;
+    }
+  } else {
+    bool should_fail = false;
+    if (error.code() == 429) {
+      should_fail = false;
+    } else if (error.code() == 400 && error.message() == "ENCRYPTION_DECLINED") {
+      should_fail = true;
+    } else {
+      LOG(ERROR) << "Got unknown error for encrypted service message: " << error;
+      should_fail = true;
+    }
+    if (should_fail) {
+      return on_fatal_error(std::move(error));
+    }
+  }
+  auto query = create_net_query(*state->message);
+  state->net_query_id = query->id();
+
+  CHECK(resend_promise);
+  auto send_message_start =
+      PromiseCreator::lambda([actor_id = actor_id(this), resend_promise = std::move(resend_promise),
+                              query = std::move(query)](Result<> result) mutable {
+        if (result.is_ok()) {
+          resend_promise.set_value(std::move(query));
+        } else {
+          send_closure(actor_id, &SecretChatActor::on_promise_error, result.move_as_error(), "resend_query");
+        }
+      });
+  if (need_sync) {
+    context_->binlog()->force_sync(std::move(send_message_start));
+  } else {
+    send_message_start.set_value(Unit());
+  }
+}
+
+void SecretChatActor::on_outbound_send_message_finish(uint64 state_id) {
+  if (close_flag_) {
+    return;
+  }
+  auto *state = outbound_message_states_.get(state_id);
+  if (!state) {
+    return;
+  }
+  LOG(INFO) << "Outbound secret message [send_message] finish " << tag("logevent_id", state->message->logevent_id());
+  state->send_message_finish_flag = true;
+  state->outer_send_message_finish.set_value(Unit());
+
+  outbound_loop(state, state_id);
+}
+
+void SecretChatActor::on_outbound_save_changes_finish(uint64 state_id) {
+  if (close_flag_) {
+    return;
+  }
+  auto *state = outbound_message_states_.get(state_id);
+  CHECK(state);
+  LOG(INFO) << "Outbound secret message [save_changes] finish " << tag("logevent_id", state->message->logevent_id());
+  state->save_changes_finish_flag = true;
+  outbound_loop(state, state_id);
+}
+
+void SecretChatActor::on_outbound_ack(uint64 state_id) {
+  if (close_flag_) {
+    return;
+  }
+  auto *state = outbound_message_states_.get(state_id);
+  CHECK(state);
+  LOG(INFO) << "Outbound secret message [ack] finish " << tag("logevent_id", state->message->logevent_id());
+  state->ack_flag = true;
+  outbound_loop(state, state_id);
+}
+
+void SecretChatActor::on_outbound_outer_send_message_promise(uint64 state_id, Promise<> promise) {
+  if (close_flag_) {
+    promise.set_error(Status::Error(400, "Chat is closed"));
+    return;
+  }
+  auto *state = outbound_message_states_.get(state_id);
+  CHECK(state);
+  LOG(INFO) << "Outbound secret message [TODO] " << tag("logevent_id", state->message->logevent_id());
+  promise.set_value(Unit());  // Seems like this message is at least stored to binlog already
+  if (state->send_result_) {
+    state->send_result_({});
+  } else {
+    context_->on_send_message_error(state->message->random_id, Status::Error(400, "Message has already been sent"),
+                                    Auto());
+  }
+}
+
+void SecretChatActor::outbound_loop(OutboundMessageState *state, uint64 state_id) {
+  if (close_flag_) {
+    return;
+  }
+  if (state->save_changes_finish_flag /*&& state->send_message_finish_flag*/ && state->ack_flag) {
+    LOG(INFO) << "Outbound message [remove_logevent] start " << tag("logevent_id", state->message->logevent_id());
+    BinlogHelper::erase(context_->binlog(), state->message->logevent_id());
+
+    random_id_to_outbound_message_state_token_.erase(state->message->random_id);
+    LOG(INFO) << "Outbound message finish (lazy) " << tag("logevent_id", state->message->logevent_id());
+    outbound_message_states_.erase(state_id);
+    return;
+  }
+
+  if (state->save_changes_finish_flag && state->send_message_finish_flag &&
+      !state->message->is_sent) {  // [rewrite_logevent]
+    LOG(INFO) << "Outbound message [rewrite_logevent] start " << tag("logevent_id", state->message->logevent_id());
+    state->message->is_sent = true;
+    BinlogHelper::rewrite(context_->binlog(), state->message->logevent_id(), LogEvent::HandlerType::SecretChats,
+                          create_storer(*state->message));
+  }
+}
+
+template <class T>
+Status SecretChatActor::save_common_info(T &update) {
+  if (auth_state_.id != update.id_) {
+    return Status::Error(PSLICE() << "chat_id mismatch: " << tag("mine", auth_state_.id) << tag("outer", update.id_));
+  }
+  auth_state_.id = update.id_;
+  auth_state_.access_hash = update.access_hash_;
+  return Status::OK();
+}
+
+Status SecretChatActor::on_update_chat(telegram_api::encryptedChatRequested &update) {
+  if (auth_state_.state != State::Empty) {
+    LOG(WARNING) << "Unexpected ChatRequested ignored: " << to_string(update);
+    return Status::OK();
+  }
+  auth_state_.state = State::SendAccept;
+  auth_state_.x = 1;
+  auth_state_.user_id = update.admin_id_;
+  auth_state_.date = context_->unix_time();
+  TRY_STATUS(save_common_info(update));
+  auth_state_.handshake.set_g_a(update.g_a_.as_slice());
+  send_update_secret_chat();
+  return Status::OK();
+}
+Status SecretChatActor::on_update_chat(telegram_api::encryptedChatEmpty &update) {
+  return Status::OK();
+}
+Status SecretChatActor::on_update_chat(telegram_api::encryptedChatWaiting &update) {
+  if (auth_state_.state != State::WaitRequestResponse && auth_state_.state != State::WaitAcceptResponse) {
+    LOG(WARNING) << "Unexpected ChatWaiting ignored";
+    return Status::OK();
+  }
+  TRY_STATUS(save_common_info(update));
+  send_update_secret_chat();
+  return Status::OK();
+}
+Status SecretChatActor::on_update_chat(telegram_api::encryptedChat &update) {
+  if (auth_state_.state != State::WaitRequestResponse && auth_state_.state != State::WaitAcceptResponse) {
+    LOG(WARNING) << "Unexpected Chat ignored";
+    return Status::OK();
+  }
+  TRY_STATUS(save_common_info(update));
+  if (auth_state_.state == State::WaitRequestResponse) {
+    auth_state_.handshake.set_g_a(update.g_a_or_b_.as_slice());
+    TRY_STATUS(auth_state_.handshake.run_checks(context_->dh_callback()));
+    auto id_and_key = auth_state_.handshake.gen_key();
+    pfs_state_.auth_key = mtproto::AuthKey(id_and_key.first, std::move(id_and_key.second));
+    calc_key_hash();
+  }
+  if (static_cast<int64>(pfs_state_.auth_key.id()) != update.key_fingerprint_) {
+    return Status::Error("Key fingerprint mismatch");
+  }
+  auth_state_.state = State::Ready;
+  if (create_logevent_id_ != 0) {
+    BinlogHelper::erase(context_->binlog(), create_logevent_id_);
+    create_logevent_id_ = 0;
+  }
+
+  // NB: order is important
+  context_->secret_chat_db()->set_value(pfs_state_);
+  context_->secret_chat_db()->set_value(auth_state_);
+  LOG(INFO) << "OK! Ready!";
+  send_update_secret_chat();
+  send_action(secret_api::make_object<secret_api::decryptedMessageActionNotifyLayer>(MY_LAYER), SendFlag::None,
+              Promise<>());
+  return Status::OK();
+}
+Status SecretChatActor::on_update_chat(telegram_api::encryptedChatDiscarded &update) {
+  return Status::Error("Chat discarded");
+}
+
+Status SecretChatActor::on_update_chat(NetQueryPtr query) {
+  static_assert(std::is_same<telegram_api::messages_requestEncryption::ReturnType,
+                             telegram_api::messages_acceptEncryption::ReturnType>::value,
+                "");
+  TRY_RESULT(config, fetch_result<telegram_api::messages_requestEncryption>(std::move(query)));
+  TRY_STATUS(on_update_chat(std::move(config)));
+  if (auth_state_.state == State::WaitRequestResponse) {
+    context_->secret_chat_db()->set_value(auth_state_);
+    context_->binlog()->force_sync(Promise<>());
+  }
+  return Status::OK();
+}
+
+Status SecretChatActor::on_update_chat(telegram_api::object_ptr<telegram_api::EncryptedChat> chat) {
+  Status res;
+  downcast_call(*chat, [&](auto &obj) { res = this->on_update_chat(obj); });
+  return res;
+}
+
+// DH CONFIG
+// messages.dhConfigNotModified#c0e24635 random:bytes = messages.DhConfig;
+// messages.dhConfig#2c221edd g:int p:bytes version:int random:bytes = messages.DhConfig;
+//---functions---
+// messages.getDhConfig#26cf8950 version:int random_length:int = messages.DhConfig;
+
+void SecretChatActor::start_up() {
+  LOG(INFO) << "SecretChatActor: start_up";
+  // auto start = Time::now();
+  auto r_auth_state = context_->secret_chat_db()->get_value<AuthState>();
+  if (r_auth_state.is_ok()) {
+    auth_state_ = r_auth_state.move_as_ok();
+  }
+  if (!can_be_empty_ && auth_state_.state == State::Empty) {
+    LOG(WARNING) << "Close Secret chat because it is empty";
+    return stop();
+  }
+  auto r_seq_no_state = context_->secret_chat_db()->get_value<SeqNoState>();
+  if (r_seq_no_state.is_ok()) {
+    seq_no_state_ = r_seq_no_state.move_as_ok();
+  }
+  auto r_config_state = context_->secret_chat_db()->get_value<ConfigState>();
+  if (r_config_state.is_ok()) {
+    config_state_ = r_config_state.move_as_ok();
+  }
+  auto r_pfs_state = context_->secret_chat_db()->get_value<PfsState>();
+  if (r_pfs_state.is_ok()) {
+    pfs_state_ = r_pfs_state.move_as_ok();
+  }
+  saved_pfs_state_message_id_ = pfs_state_.message_id;
+  pfs_state_.last_timestamp = Time::now();
+
+  send_update_secret_chat();
+  get_dh_config();
+
+  // auto end = Time::now();
+  // CHECK(end - start < 0.2);
+  LOG(INFO) << "start_up with SeqNoState=" << seq_no_state_;
+  LOG(INFO) << "start_up with PfsState=" << pfs_state_;
+}
+
+void SecretChatActor::get_dh_config() {
+  if (auth_state_.state != State::Empty) {
+    return;
+  }
+
+  auto dh_config = context_->dh_config();
+  if (dh_config) {
+    auth_state_.dh_config = *dh_config;
+  }
+
+  auto version = auth_state_.dh_config.version;
+  int random_length = 0;
+  telegram_api::messages_getDhConfig tl_query(version, random_length);
+
+  auto query = context_->net_query_creator().create(
+      UniqueId::next(UniqueId::Type::Default, static_cast<uint8>(QueryType::DhConfig)), create_storer(tl_query));
+  context_->send_net_query(std::move(query), actor_shared(this), false);
+}
+
+Status SecretChatActor::on_dh_config(NetQueryPtr query) {
+  LOG(INFO) << "Got dh config";
+  TRY_RESULT(config, fetch_result<telegram_api::messages_getDhConfig>(std::move(query)));
+  downcast_call(*config, [&](auto &obj) { this->on_dh_config(obj); });
+  auth_state_.handshake.set_config(auth_state_.dh_config.g, auth_state_.dh_config.prime);
+  return Status::OK();
+}
+void SecretChatActor::on_dh_config(telegram_api::messages_dhConfigNotModified &dh_not_modified) {
+  // TODO: use random_
+}
+void SecretChatActor::on_dh_config(telegram_api::messages_dhConfig &dh) {
+  auto dh_config = std::make_shared<DhConfig>();
+  dh_config->version = dh.version_;
+  dh_config->prime = dh.p_.as_slice().str();
+  dh_config->g = dh.g_;
+  // TODO: use random_
+  auth_state_.dh_config = *dh_config;
+  context_->set_dh_config(dh_config);
+}
+
+void SecretChatActor::calc_key_hash() {
+  unsigned char sha1_buf[20];
+  auto sha1_slice = Slice(sha1_buf, 20);
+  sha1(pfs_state_.auth_key.key(), sha1_buf);
+
+  unsigned char sha256_buf[32];
+  auto sha256_slice = MutableSlice(sha256_buf, 32);
+  sha256(pfs_state_.auth_key.key(), sha256_slice);
+
+  auth_state_.key_hash = sha1_slice.truncate(16).str() + sha256_slice.truncate(20).str();
+}
+
+void SecretChatActor::send_update_secret_chat() {
+  if (auth_state_.state == State::Empty) {
+    return;
+  }
+  SecretChatState state;
+  if (auth_state_.state == State::Ready) {
+    state = SecretChatState::Active;
+  } else if (auth_state_.state == State::Closed) {
+    state = SecretChatState::Closed;
+  } else {
+    state = SecretChatState::Waiting;
+  }
+  context_->on_update_secret_chat(auth_state_.access_hash, get_user_id(), state, auth_state_.x == 0, config_state_.ttl,
+                                  auth_state_.date, auth_state_.key_hash, current_layer());
+}
+
+void SecretChatActor::on_outbound_action(secret_api::decryptedMessageActionSetMessageTTL &set_ttl) {
+  config_state_.ttl = set_ttl.ttl_seconds_;
+  context_->secret_chat_db()->set_value(config_state_);
+  send_update_secret_chat();
+}
+void SecretChatActor::on_outbound_action(secret_api::decryptedMessageActionReadMessages &read_messages) {
+  // TODO
+}
+void SecretChatActor::on_outbound_action(secret_api::decryptedMessageActionDeleteMessages &delete_messages) {
+  // Corresponding logevent won't be deleted before promise returned by add_changes is set.
+  on_delete_messages(delete_messages.random_ids_).ensure();
+}
+void SecretChatActor::on_outbound_action(secret_api::decryptedMessageActionScreenshotMessages &screenshot) {
+  // noting to do
+}
+void SecretChatActor::on_outbound_action(secret_api::decryptedMessageActionFlushHistory &flush_history) {
+  on_flush_history(pfs_state_.message_id).ensure();
+}
+void SecretChatActor::on_outbound_action(secret_api::decryptedMessageActionResend &resend) {
+  if (seq_no_state_.resend_end_seq_no < resend.end_seq_no_ / 2) {  // replay protection
+    seq_no_state_.resend_end_seq_no = resend.end_seq_no_ / 2;
+    on_seq_no_state_changed();
+  }
+}
+void SecretChatActor::on_outbound_action(secret_api::decryptedMessageActionNotifyLayer &notify_layer) {
+  config_state_.my_layer = notify_layer.layer_;
+  context_->secret_chat_db()->set_value(config_state_);
+}
+void SecretChatActor::on_outbound_action(secret_api::decryptedMessageActionTyping &typing) {
+  // noop
+}
+
+Status SecretChatActor::on_inbound_action(secret_api::decryptedMessageActionSetMessageTTL &set_ttl) {
+  config_state_.ttl = set_ttl.ttl_seconds_;
+  context_->secret_chat_db()->set_value(config_state_);
+  send_update_secret_chat();
+  return Status::OK();
+}
+Status SecretChatActor::on_inbound_action(secret_api::decryptedMessageActionReadMessages &read_messages) {
+  // TODO
+  return Status::OK();
+}
+Status SecretChatActor::on_inbound_action(secret_api::decryptedMessageActionDeleteMessages &delete_messages) {
+  return on_delete_messages(delete_messages.random_ids_);
+}
+Status SecretChatActor::on_inbound_action(secret_api::decryptedMessageActionScreenshotMessages &screenshot) {
+  // TODO
+  return Status::OK();
+}
+Status SecretChatActor::on_inbound_action(secret_api::decryptedMessageActionFlushHistory &screenshot) {
+  return on_flush_history(pfs_state_.message_id);
+}
+Status SecretChatActor::on_inbound_action(secret_api::decryptedMessageActionResend &resend) {
+  return Status::OK();
+}
+Status SecretChatActor::on_inbound_action(secret_api::decryptedMessageActionNotifyLayer &notify_layer) {
+  if (notify_layer.layer_ > config_state_.his_layer) {
+    config_state_.his_layer = notify_layer.layer_;
+    context_->secret_chat_db()->set_value(config_state_);
+    send_update_secret_chat();
+  }
+  return Status::OK();
+}
+Status SecretChatActor::on_inbound_action(secret_api::decryptedMessageActionTyping &typing) {
+  // noop
+  return Status::OK();
+}
+
+// Perfect Forward Secrecy
+void SecretChatActor::on_outbound_action(secret_api::decryptedMessageActionRequestKey &request_key) {
+  CHECK(pfs_state_.state == PfsState::WaitSendRequest || pfs_state_.state == PfsState::SendRequest);
+  pfs_state_.state = PfsState::WaitRequestResponse;
+  on_pfs_state_changed();
+}
+void SecretChatActor::on_outbound_action(secret_api::decryptedMessageActionAcceptKey &accept_key) {
+  CHECK(pfs_state_.state == PfsState::WaitSendAccept || pfs_state_.state == PfsState::SendAccept);
+  pfs_state_.state = PfsState::WaitAcceptResponse;
+  pfs_state_.handshake = DhHandshake();
+  on_pfs_state_changed();
+}
+void SecretChatActor::on_outbound_action(secret_api::decryptedMessageActionAbortKey &abort_key) {
+  // TODO
+  LOG(FATAL) << "TODO";
+}
+void SecretChatActor::on_outbound_action(secret_api::decryptedMessageActionCommitKey &commit_key) {
+  CHECK(pfs_state_.state == PfsState::WaitSendCommit || pfs_state_.state == PfsState::SendCommit);
+
+  CHECK(static_cast<int64>(pfs_state_.other_auth_key.id()) == commit_key.key_fingerprint_);
+  std::swap(pfs_state_.auth_key, pfs_state_.other_auth_key);
+  pfs_state_.can_forget_other_key = true;
+
+  pfs_state_.state = PfsState::Empty;
+  pfs_state_.last_message_id = pfs_state_.message_id;
+  pfs_state_.last_timestamp = Time::now();
+  pfs_state_.last_out_seq_no = seq_no_state_.my_out_seq_no;
+
+  on_pfs_state_changed();
+}
+void SecretChatActor::on_outbound_action(secret_api::decryptedMessageActionNoop &noop) {
+  // noop
+}
+
+// decryptedMessageActionRequestKey#f3c9611b exchange_id:long g_a:bytes = DecryptedMessageAction;
+Status SecretChatActor::on_inbound_action(secret_api::decryptedMessageActionRequestKey &request_key) {
+  if (pfs_state_.state == PfsState::WaitRequestResponse || pfs_state_.state == PfsState::SendRequest) {
+    if (pfs_state_.exchange_id > request_key.exchange_id_) {
+      LOG(INFO) << "RequestKey: silently abort his request";
+      return Status::OK();
+    } else {
+      pfs_state_.state = PfsState::Empty;
+      if (pfs_state_.exchange_id == request_key.exchange_id_) {
+        context_->secret_chat_db()->set_value(pfs_state_);
+        LOG(WARNING) << "RequestKey: silently abort both requests (almost impossible)";
+        return Status::OK();
+      }
+    }
+  }
+
+  if (pfs_state_.state != PfsState::Empty) {
+    return Status::Error("Unexpected RequestKey");
+  }
+  CHECK(pfs_state_.other_auth_key.empty()) << "TODO: got requestKey, before old key is dropped";
+  pfs_state_.state = PfsState::SendAccept;
+  pfs_state_.handshake = DhHandshake();
+  pfs_state_.exchange_id = request_key.exchange_id_;
+  pfs_state_.handshake.set_config(auth_state_.dh_config.g, auth_state_.dh_config.prime);
+  pfs_state_.handshake.set_g_a(request_key.g_a_.as_slice());
+  TRY_STATUS(pfs_state_.handshake.run_checks(context_->dh_callback()));
+  auto id_and_key = pfs_state_.handshake.gen_key();
+
+  pfs_state_.other_auth_key = mtproto::AuthKey(id_and_key.first, std::move(id_and_key.second));
+  pfs_state_.can_forget_other_key = false;
+  pfs_state_.wait_message_id = pfs_state_.message_id;
+
+  on_pfs_state_changed();
+  return Status::OK();
+}
+
+// decryptedMessageActionAcceptKey#6fe1735b exchange_id:long g_b:bytes key_fingerprint:long = DecryptedMessageAction;
+Status SecretChatActor::on_inbound_action(secret_api::decryptedMessageActionAcceptKey &accept_key) {
+  if (pfs_state_.state != PfsState::WaitRequestResponse) {
+    return Status::Error("AcceptKey: unexpected");
+  }
+  if (pfs_state_.exchange_id != accept_key.exchange_id_) {
+    return Status::Error("AcceptKey: exchange_id mismatch");
+  }
+  pfs_state_.handshake.set_g_a(accept_key.g_b_.as_slice());
+  TRY_STATUS(pfs_state_.handshake.run_checks(context_->dh_callback()));
+  auto id_and_key = pfs_state_.handshake.gen_key();
+  if (static_cast<int64>(id_and_key.first) != accept_key.key_fingerprint_) {
+    return Status::Error("AcceptKey: key_fingerprint mismatch");
+  }
+  pfs_state_.state = PfsState::SendCommit;
+  pfs_state_.handshake = DhHandshake();
+  CHECK(pfs_state_.can_forget_other_key || static_cast<int64>(pfs_state_.other_auth_key.id()) == id_and_key.first);
+  pfs_state_.other_auth_key = mtproto::AuthKey(id_and_key.first, std::move(id_and_key.second));
+  pfs_state_.can_forget_other_key = false;
+  pfs_state_.wait_message_id = pfs_state_.message_id;
+
+  on_pfs_state_changed();
+  return Status::OK();
+}
+Status SecretChatActor::on_inbound_action(secret_api::decryptedMessageActionAbortKey &abort_key) {
+  if (pfs_state_.exchange_id != abort_key.exchange_id_) {
+    LOG(INFO) << "AbortKey: exchange_id mismatch: " << tag("my exchange_id", pfs_state_.exchange_id)
+              << to_string(abort_key);
+    return Status::OK();
+  }
+  if (pfs_state_.state != PfsState::WaitRequestResponse) {
+    return Status::Error("AbortKey: unexpected");
+  }
+  pfs_state_.state = PfsState::Empty;
+  pfs_state_.handshake = DhHandshake();
+
+  on_pfs_state_changed();
+  return Status::OK();
+}
+Status SecretChatActor::on_inbound_action(secret_api::decryptedMessageActionCommitKey &commit_key) {
+  if (pfs_state_.state != PfsState::WaitAcceptResponse) {
+    return Status::Error("CommitKey: unexpected");
+  }
+  if (pfs_state_.exchange_id != commit_key.exchange_id_) {
+    return Status::Error("CommitKey: exchange_id mismatch ");
+  }
+
+  CHECK(!pfs_state_.can_forget_other_key);
+  if (static_cast<int64>(pfs_state_.other_auth_key.id()) != commit_key.key_fingerprint_) {
+    return Status::Error("CommitKey: fingerprint mismatch");
+  }
+  std::swap(pfs_state_.auth_key, pfs_state_.other_auth_key);
+  pfs_state_.can_forget_other_key = true;
+
+  pfs_state_.state = PfsState::Empty;
+  pfs_state_.last_message_id = pfs_state_.message_id;
+  pfs_state_.last_timestamp = Time::now();
+  pfs_state_.last_out_seq_no = seq_no_state_.my_out_seq_no;
+
+  on_pfs_state_changed();
+  return Status::OK();
+}
+Status SecretChatActor::on_inbound_action(secret_api::decryptedMessageActionNoop &noop) {
+  // noop
+  return Status::OK();
+}
+
+Status SecretChatActor::on_inbound_action(secret_api::DecryptedMessageAction &action, int32 message_id) {
+  // Action may be not about PFS, but we still can use pfs_state_.message_id
+  if (message_id <= pfs_state_.message_id) {  // replay protection
+    LOG(INFO) << "Drop old inbound DecryptedMessageAction: " << to_string(action) << tag("message_id", message_id)
+              << tag("known_message_id", pfs_state_.message_id);
+    return Status::OK();
+  }
+
+  // if message_id < seq_no_state_.message_id, then SeqNoState with message_id bigger than current message_id is already saved.
+  // And event corresponding to message_id is saved too.
+  //
+  // Also, if SeqNoState with message_id greater than current message_id is not saved, then corresponding action will be
+  // replayed.
+  //
+  // This works only for ttl, not for pfs. Same ttl action may be processed twice.
+  if (message_id < seq_no_state_.message_id) {
+    LOG(INFO) << "Drop old inbound DecryptedMessageAction (non-pfs action): " << to_string(action);
+    return Status::OK();
+  }
+  pfs_state_.message_id = message_id;  // replay protection
+
+  LOG(INFO) << "on_inbound_action: " << to_string(action);
+  Status res;
+  downcast_call(action, [&](auto &obj) { res = this->on_inbound_action(obj); });
+  return res;
+}
+
+void SecretChatActor::on_outbound_action(secret_api::DecryptedMessageAction &action, int32 message_id) {
+  // Action may be not about PFS, but we still can use pfs_state_.message_id
+  if (message_id <= pfs_state_.message_id) {  // replay protection
+    LOG(INFO) << "Drop old outbound DecryptedMessageAction: " << to_string(action);
+    return;
+  }
+
+  // see comment in on_inbound_action
+  if (message_id < seq_no_state_.message_id) {
+    LOG(INFO) << "Drop old outbound DecryptedMessageAction (non-pfs action): " << to_string(action);
+    return;
+  }
+  pfs_state_.message_id = message_id;  // replay protection
+
+  LOG(INFO) << "on_outbound_action: " << to_string(action);
+  downcast_call(action, [&](auto &obj) { this->on_outbound_action(obj); });
+}
+
+// decryptedMessageActionRequestKey#f3c9611b exchange_id:long g_a:bytes = DecryptedMessageAction;
+void SecretChatActor::request_new_key() {
+  CHECK(!auth_state_.dh_config.empty());
+
+  pfs_state_.state = PfsState::SendRequest;
+  pfs_state_.handshake = DhHandshake();
+  pfs_state_.handshake.set_config(auth_state_.dh_config.g, auth_state_.dh_config.prime);
+  pfs_state_.exchange_id = Random::secure_int64();
+
+  // NB: must save explicitly
+  LOG(INFO) << "SAVE PfsState " << pfs_state_;
+  context_->secret_chat_db()->set_value(pfs_state_);
+}
+
+void SecretChatActor::on_promise_error(Status error, string desc) {
+  if (context_->close_flag()) {
+    // ignore
+    LOG(ERROR) << "IGNORE";
+    return;
+  }
+  LOG(FATAL) << "Failed: " << tag("promise", desc) << error;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/SecretChatActor.h b/libs/tdlib/td/td/telegram/SecretChatActor.h
new file mode 100644
index 0000000000..79f73981e1
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/SecretChatActor.h
@@ -0,0 +1,676 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/mtproto/AuthKey.h"
+#include "td/mtproto/crypto.h"
+#include "td/mtproto/Transport.h"
+
+#include "td/telegram/DhConfig.h"
+#include "td/telegram/logevent/SecretChatEvent.h"
+#include "td/telegram/MessageId.h"
+#include "td/telegram/PtsManager.h"
+#include "td/telegram/SecretChatDb.h"
+#include "td/telegram/SecretChatId.h"
+#include "td/telegram/UserId.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/ChangesProcessor.h"
+#include "td/utils/Container.h"
+#include "td/utils/format.h"
+#include "td/utils/port/Clocks.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/Time.h"
+#include "td/utils/tl_helpers.h"
+
+#include <functional>
+#include <map>
+#include <memory>
+#include <tuple>
+#include <utility>
+
+namespace td {
+class BinlogInterface;
+class DhCache;
+class NetQueryCreator;
+class SequenceDispatcher;
+
+class SecretChatActor : public NetQueryCallback {
+ public:
+  // do not change DEFAULT_LAYER, unless all it's usages are fixed
+  enum : int32 { DEFAULT_LAYER = 46, VOICE_NOTES_LAYER = 66, MTPROTO_2_LAYER = 73, MY_LAYER = MTPROTO_2_LAYER };
+
+  class Context {
+   public:
+    Context() = default;
+    Context(const Context &) = delete;
+    Context &operator=(const Context &) = delete;
+    virtual ~Context() = default;
+    virtual DhCallback *dh_callback() = 0;
+    virtual BinlogInterface *binlog() = 0;
+    virtual SecretChatDb *secret_chat_db() = 0;
+
+    virtual NetQueryCreator &net_query_creator() = 0;
+    virtual std::shared_ptr<DhConfig> dh_config() = 0;
+    virtual void set_dh_config(std::shared_ptr<DhConfig> dh_config) = 0;
+
+    virtual bool get_config_option_boolean(const string &name) const = 0;
+
+    virtual int32 unix_time() = 0;
+
+    virtual bool close_flag() = 0;
+
+    // We don't want to expose the whole NetQueryDispatcher, MessagesManager and ContactsManager.
+    // So it is more clear which parts of MessagesManager is really used. And it is much easier to create tests.
+    virtual void send_net_query(NetQueryPtr query, ActorShared<NetQueryCallback> callback, bool ordered) = 0;
+
+    virtual void on_update_secret_chat(int64 access_hash, UserId user_id, SecretChatState state, bool is_outbound,
+                                       int32 ttl, int32 date, string key_hash, int32 layer) = 0;
+
+    // Promise must be set only after the update is processed.
+    //
+    // For example, one may set promise, after update was sent to binlog. It is ok, because SecretChatsActor will delete
+    // this update thought binlog too. So it wouldn't be deleted before update is saved.
+
+    // inbound messages
+    virtual void on_inbound_message(UserId user_id, MessageId message_id, int32 date,
+                                    tl_object_ptr<telegram_api::encryptedFile> file,
+                                    tl_object_ptr<secret_api::decryptedMessage> message, Promise<> promise) = 0;
+    virtual void on_delete_messages(std::vector<int64> random_id, Promise<> promise) = 0;
+    virtual void on_flush_history(MessageId message_id, Promise<> promise) = 0;
+    virtual void on_read_message(int64 random_id, Promise<> promise) = 0;
+    virtual void on_screenshot_taken(UserId user_id, MessageId message_id, int32 date, int64 random_id,
+                                     Promise<> promise) = 0;
+    virtual void on_set_ttl(UserId user_id, MessageId message_id, int32 date, int32 ttl, int64 random_id,
+                            Promise<> promise) = 0;
+
+    // outbound messages
+    virtual void on_send_message_ack(int64 random_id) = 0;
+    virtual void on_send_message_ok(int64 random_id, MessageId message_id, int32 date,
+                                    tl_object_ptr<telegram_api::EncryptedFile> file, Promise<> promise) = 0;
+    virtual void on_send_message_error(int64 random_id, Status error, Promise<> promise) = 0;
+  };
+
+  SecretChatActor(int32 id, std::unique_ptr<Context> context, bool can_be_empty);
+
+  // First query to new chat must be on of this two
+  void update_chat(telegram_api::object_ptr<telegram_api::EncryptedChat> chat);
+  void create_chat(int32 user_id, int64 user_access_hash, int32 random_id, Promise<SecretChatId> promise);
+  void cancel_chat(Promise<> promise);
+
+  // Inbound messages
+  // Logevent is created by SecretChatsManager, because it must contain qts
+  void add_inbound_message(std::unique_ptr<logevent::InboundSecretMessage> message);
+
+  // Outbound messages
+  // Promise will be set just after correspoiding logevent will be SENT to binlog.
+  void send_message(tl_object_ptr<secret_api::DecryptedMessage> message,
+                    tl_object_ptr<telegram_api::InputEncryptedFile> file, Promise<> promise);
+  void send_message_action(tl_object_ptr<secret_api::SendMessageAction> action);
+  void send_read_history(int32 date,
+                         Promise<>);  // no binlog event. TODO: Promise will be set after the net query is sent
+  void send_open_message(int64 random_id, Promise<>);
+  void delete_message(int64 random_id, Promise<> promise);
+  void delete_messages(std::vector<int64> random_ids, Promise<> promise);
+  void delete_all_messages(Promise<> promise);
+  void notify_screenshot_taken(Promise<> promise);
+  void send_set_ttl_message(int32 ttl, int64 random_id, Promise<> promise);
+
+  // Binlog replay interface
+  void replay_inbound_message(std::unique_ptr<logevent::InboundSecretMessage> message);
+  void replay_outbound_message(std::unique_ptr<logevent::OutboundSecretMessage> message);
+  void replay_close_chat(std::unique_ptr<logevent::CloseSecretChat> event);
+  void replay_create_chat(std::unique_ptr<logevent::CreateSecretChat> event);
+  void binlog_replay_finish();
+
+ private:
+  enum class State { Empty, SendRequest, SendAccept, WaitRequestResponse, WaitAcceptResponse, Ready, Closed };
+  enum { MAX_RESEND_COUNT = 1000 };
+
+  // We have git state that should be shynchronized with db.
+  // It is splitted into several parts because:
+  // 1. Some parts are BIG (auth_key, for example) and are rarely updated.
+  // 2. Other are frequently updated, so probably should be as small as possible.
+  // 3. Some parts must be updated atomically.
+  struct SeqNoState {
+    int32 message_id = 0;
+    int32 my_in_seq_no = 0;
+    int32 my_out_seq_no = 0;
+    int32 his_in_seq_no = 0;
+
+    int32 resend_end_seq_no = -1;
+
+    static Slice key() {
+      return Slice("state");
+    }
+    template <class StorerT>
+    void store(StorerT &storer) const {
+      storer.store_int(message_id);
+      storer.store_int(my_in_seq_no);
+      storer.store_int(my_out_seq_no);
+      storer.store_int(his_in_seq_no);
+      storer.store_int(resend_end_seq_no);
+    }
+
+    template <class ParserT>
+    void parse(ParserT &parser) {
+      message_id = parser.fetch_int();
+      my_in_seq_no = parser.fetch_int();
+      my_out_seq_no = parser.fetch_int();
+      his_in_seq_no = parser.fetch_int();
+      resend_end_seq_no = parser.fetch_int();
+    }
+  };
+
+  struct ConfigState {
+    int32 his_layer = 8;
+    int32 my_layer = 8;
+    int32 ttl = 0;
+
+    static Slice key() {
+      return Slice("config");
+    }
+    template <class StorerT>
+    void store(StorerT &storer) const {
+      storer.store_int(his_layer | HAS_FLAGS);
+      storer.store_int(ttl);
+      storer.store_int(my_layer);
+      //for future usage
+      BEGIN_STORE_FLAGS();
+      END_STORE_FLAGS();
+    }
+
+    template <class ParserT>
+    void parse(ParserT &parser) {
+      his_layer = parser.fetch_int();
+      ttl = parser.fetch_int();
+      bool has_flags = (his_layer & HAS_FLAGS) != 0;
+      if (has_flags) {
+        his_layer &= ~HAS_FLAGS;
+        my_layer = parser.fetch_int();
+        // for future usage
+        BEGIN_PARSE_FLAGS();
+        END_PARSE_FLAGS();
+      }
+    }
+
+    enum { HAS_FLAGS = 1 << 31 };
+  };
+
+  // PfsAction
+  struct PfsState {
+    enum State : int32 {
+      Empty,
+      WaitSendRequest,
+      SendRequest,
+      WaitRequestResponse,
+      WaitSendAccept,
+      SendAccept,
+      WaitAcceptResponse,
+      WaitSendCommit,
+      SendCommit
+    } state = Empty;
+
+    enum Flags : int32 { CanForgetOtherKey = 1 };
+    mtproto::AuthKey auth_key;
+    mtproto::AuthKey other_auth_key;
+    bool can_forget_other_key = true;
+
+    int32 message_id = 0;  // to skip old actions
+    int32 wait_message_id = 0;
+    int64 exchange_id = 0;
+    int32 last_message_id = 0;
+    double last_timestamp = 0;
+    int32 last_out_seq_no = 0;
+    DhHandshake handshake;
+
+    static Slice key() {
+      return Slice("pfs_state");
+    }
+
+    template <class StorerT>
+    void store(StorerT &storer) const {
+      int32 flags = 0;
+      if (can_forget_other_key) {
+        flags |= CanForgetOtherKey;
+      }
+      storer.store_int(flags);
+      storer.store_int(state);
+      auth_key.store(storer);
+      other_auth_key.store(storer);
+      storer.store_int(message_id);
+      storer.store_long(exchange_id);
+      storer.store_int(last_message_id);
+      storer.store_long(static_cast<int64>((last_timestamp - Time::now() + Clocks::system()) * 1000000));
+      storer.store_int(last_out_seq_no);
+      handshake.store(storer);
+    }
+    template <class ParserT>
+    void parse(ParserT &parser) {
+      int32 flags = parser.fetch_int();
+      can_forget_other_key = (flags & CanForgetOtherKey) != 0;
+      state = static_cast<State>(parser.fetch_int());
+      auth_key.parse(parser);
+      other_auth_key.parse(parser);
+      message_id = parser.fetch_int();
+      exchange_id = parser.fetch_long();
+      last_message_id = parser.fetch_int();
+      last_timestamp = static_cast<double>(parser.fetch_long()) / 1000000 - Clocks::system() + Time::now();
+      if (last_timestamp > Time::now_cached()) {
+        last_timestamp = Time::now_cached();
+      }
+      last_out_seq_no = parser.fetch_int();
+      handshake.parse(parser);
+    }
+  };
+  friend StringBuilder &operator<<(StringBuilder &sb, const PfsState &state) {
+    return sb << "PfsState["
+              << tag("state",
+                     [&] {
+                       switch (state.state) {
+                         case PfsState::Empty:
+                           return "Empty";
+                         case PfsState::WaitSendRequest:
+                           return "WaitSendRequest";
+                         case PfsState::SendRequest:
+                           return "SendRequest";
+                         case PfsState::WaitRequestResponse:
+                           return "WaitRequestResponse";
+                         case PfsState::WaitSendAccept:
+                           return "WaitSendAccept";
+                         case PfsState::SendAccept:
+                           return "SendAccept";
+                         case PfsState::WaitAcceptResponse:
+                           return "WaitAcceptResponse";
+                         case PfsState::WaitSendCommit:
+                           return "WaitSendCommit";
+                         case PfsState::SendCommit:
+                           return "SendCommit";
+                       }
+                       return "UNKNOWN";
+                     }())
+              << tag("message_id", state.message_id) << tag("auth_key", format::as_hex(state.auth_key.id()))
+              << tag("last_message_id", state.last_message_id)
+              << tag("other_auth_key", format::as_hex(state.other_auth_key.id()))
+              << tag("can_forget", state.can_forget_other_key) << "]";
+  }
+
+  PfsState pfs_state_;
+  bool pfs_state_changed_ = false;
+
+  void on_outbound_action(secret_api::decryptedMessageActionSetMessageTTL &set_ttl);
+  void on_outbound_action(secret_api::decryptedMessageActionReadMessages &read_messages);
+  void on_outbound_action(secret_api::decryptedMessageActionDeleteMessages &delete_messages);
+  void on_outbound_action(secret_api::decryptedMessageActionScreenshotMessages &screenshot);
+  void on_outbound_action(secret_api::decryptedMessageActionFlushHistory &flush_history);
+  void on_outbound_action(secret_api::decryptedMessageActionResend &resend);
+  void on_outbound_action(secret_api::decryptedMessageActionNotifyLayer &notify_layer);
+  void on_outbound_action(secret_api::decryptedMessageActionTyping &typing);
+
+  Status on_inbound_action(secret_api::decryptedMessageActionSetMessageTTL &set_ttl);
+  Status on_inbound_action(secret_api::decryptedMessageActionReadMessages &read_messages);
+  Status on_inbound_action(secret_api::decryptedMessageActionDeleteMessages &delete_messages);
+  Status on_inbound_action(secret_api::decryptedMessageActionScreenshotMessages &screenshot);
+  Status on_inbound_action(secret_api::decryptedMessageActionFlushHistory &screenshot);
+
+  Status on_inbound_action(secret_api::decryptedMessageActionResend &resend);
+  Status on_inbound_action(secret_api::decryptedMessageActionNotifyLayer &notify_layer);
+  Status on_inbound_action(secret_api::decryptedMessageActionTyping &typing);
+
+  // Perfect Forward Secrecy
+  void on_outbound_action(secret_api::decryptedMessageActionRequestKey &request_key);
+  void on_outbound_action(secret_api::decryptedMessageActionAcceptKey &accept_key);
+  void on_outbound_action(secret_api::decryptedMessageActionAbortKey &abort_key);
+  void on_outbound_action(secret_api::decryptedMessageActionCommitKey &commit_key);
+  void on_outbound_action(secret_api::decryptedMessageActionNoop &noop);
+
+  Status on_inbound_action(secret_api::decryptedMessageActionRequestKey &request_key);
+  Status on_inbound_action(secret_api::decryptedMessageActionAcceptKey &accept_key);
+  Status on_inbound_action(secret_api::decryptedMessageActionAbortKey &abort_key);
+  Status on_inbound_action(secret_api::decryptedMessageActionCommitKey &commit_key);
+  Status on_inbound_action(secret_api::decryptedMessageActionNoop &noop);
+
+  Status on_inbound_action(secret_api::DecryptedMessageAction &action, int32 message_id);
+
+  void on_outbound_action(secret_api::DecryptedMessageAction &action, int32 message_id);
+
+  void request_new_key();
+
+  struct AuthState {
+    State state = State::Empty;
+    int x = -1;
+    string key_hash;
+
+    int32 id = 0;
+    int64 access_hash = 0;
+
+    int32 user_id = 0;
+    int64 user_access_hash = 0;
+    int32 random_id = 0;
+
+    int32 date = 0;
+
+    DhConfig dh_config;
+    DhHandshake handshake;
+
+    static Slice key() {
+      return Slice("auth_state");
+    }
+    template <class StorerT>
+    void store(StorerT &storer) const {
+      uint32 flags = 0;
+      bool date_flag = date != 0;
+      bool key_hash_flag = true;
+      if (date_flag) {
+        flags |= 1;
+      }
+      if (key_hash_flag) {
+        flags |= 2;
+      }
+      storer.store_int((flags << 8) | static_cast<int32>(state));
+      storer.store_int(x);
+
+      storer.store_int(id);
+      storer.store_long(access_hash);
+      storer.store_int(user_id);
+      storer.store_long(user_access_hash);
+      storer.store_int(random_id);
+      if (date_flag) {
+        storer.store_int(date);
+      }
+      if (key_hash_flag) {
+        storer.store_string(key_hash);
+      }
+      dh_config.store(storer);
+      if (state == State::SendRequest || state == State::WaitRequestResponse) {
+        handshake.store(storer);
+      }
+    }
+
+    template <class ParserT>
+    void parse(ParserT &parser) {
+      uint32 tmp = parser.fetch_int();
+      state = static_cast<State>(tmp & 255);
+      uint32 flags = tmp >> 8;
+      bool date_flag = (flags & 1) != 0;
+      bool key_hash_flag = (flags & 2) != 0;
+
+      x = parser.fetch_int();
+
+      id = parser.fetch_int();
+      access_hash = parser.fetch_long();
+      user_id = parser.fetch_int();
+      user_access_hash = parser.fetch_long();
+      random_id = parser.fetch_int();
+      if (date_flag) {
+        date = parser.fetch_int();
+      }
+      if (key_hash_flag) {
+        key_hash = parser.template fetch_string<std::string>();
+      }
+      dh_config.parse(parser);
+      if (state == State::SendRequest || state == State::WaitRequestResponse) {
+        handshake.parse(parser);
+      }
+    }
+  };
+
+  std::shared_ptr<SecretChatDb> db_;
+  std::unique_ptr<Context> context_;
+
+  bool binlog_replay_finish_flag_ = false;
+  bool close_flag_ = false;
+  LogEvent::Id close_logevent_id_ = 0;
+
+  LogEvent::Id create_logevent_id_ = 0;
+
+  enum class QueryType : uint8 { DhConfig, EncryptedChat, Message, Ignore, DiscardEncryption };
+
+  bool can_be_empty_;
+  AuthState auth_state_;
+  ConfigState config_state_;
+
+  // Turns out, that all changes should be made made through StateChange.
+  //
+  // The problem is the time between the moment we made decision about change and
+  // the moment we actually apply the change to memory.
+  // We may accept some other change during that time, and there goes our problem
+  // The reason for the change may already be invalid. So we should somehow recheck change, that
+  // is already written to binlog, and apply it only if necessary.
+  // This is completly flawed.
+  // (A-start_save_to_binlog ----> B-start_save_to_binlog+change_memory ----> A-finish_save_to_binlog+surprise)
+  //
+  // Instead I suggest general solution that is already used with SeqNoState and Qts
+  // 1. We APPLY CHANGE to memory immidiately AFTER correspoding EVENT is SENT to the binlog.
+  // 2. We SEND CHANGE to db only after correspoiding EVENT is SAVED to the binlog.
+  // 3. The we are able to ERASE EVENT just AFTER the CHANGE is SAVED to the binlog.
+  //
+  // Actually the change will be saved do binlog too.
+  // So we can do it immidiatelly after EVENT is SENT to the binlog, because SEND CHANGE and ERASE EVENT will be
+  // ordered automatically.
+  //
+  // We will use common ChangeProcessor for all changes (inside one SecretChatActor).
+  // So all changes will be saved in exactly the same order as they are applied
+
+  template <class StateT>
+  class Change {
+   public:
+    Change() = default;
+    explicit operator bool() const {
+      return !data.empty();
+    }
+    explicit Change(const StateT &state) {
+      data = serialize(state);
+      message_id = state.message_id;
+    }
+    template <class StorerT>
+    void store(StorerT &storer) const {
+      // NB: rely that storer will the same as in serialize
+      storer.store_slice(data);
+    }
+    static Slice key() {
+      return StateT::key();
+    }
+
+    friend StringBuilder &operator<<(StringBuilder &sb, const Change<StateT> &change) {
+      if (change) {
+        StateT state;
+        unserialize(state, change.data).ensure();
+        return sb << state;
+      }
+      return sb;
+    }
+
+    int32 message_id;
+
+   private:
+    std::string data;
+  };
+
+  // SeqNoState
+  using SeqNoStateChange = Change<SeqNoState>;
+  using PfsStateChange = Change<PfsState>;
+  struct StateChange {
+    // TODO(perf): Less allocations, please? May be BufferSlice instead of std::string?
+    SeqNoStateChange seq_no_state_change;
+    PfsStateChange pfs_state_change;
+    Promise<Unit> save_changes_finish;
+  };
+
+  ChangesProcessor<StateChange> changes_processor_;
+  int32 saved_pfs_state_message_id_;
+
+  SeqNoState seq_no_state_;
+  bool seq_no_state_changed_ = false;
+  int32 last_binlog_message_id_ = -1;
+
+  Status check_seq_no(int in_seq_no, int out_seq_no) TD_WARN_UNUSED_RESULT;
+  void on_his_in_seq_no_updated();
+
+  void on_seq_no_state_changed();
+  template <class T>
+  void update_seq_no_state(const T &new_seq_no_state);
+  void on_pfs_state_changed();
+  Promise<> add_changes(Promise<> save_changes_finish = Promise<>());
+  // called only via Promise
+  void on_save_changes_start(ChangesProcessor<StateChange>::Id save_changes_token);
+
+  // InboundMessage
+  struct InboundMessageState {
+    bool save_changes_finish = false;
+    bool save_message_finish = false;
+    LogEvent::Id logevent_id = 0;
+    int32 message_id;
+  };
+  Container<InboundMessageState> inbound_message_states_;
+
+  std::map<int32, std::unique_ptr<logevent::InboundSecretMessage>> pending_inbound_messages_;
+
+  Result<std::tuple<uint64, BufferSlice, int32>> decrypt(BufferSlice &encrypted_message);
+
+  Status do_inbound_message_encrypted(std::unique_ptr<logevent::InboundSecretMessage> message);
+  Status do_inbound_message_decrypted_unchecked(std::unique_ptr<logevent::InboundSecretMessage> message);
+  Status do_inbound_message_decrypted(std::unique_ptr<logevent::InboundSecretMessage> message);
+  Status do_inbound_message_decrypted_pending(std::unique_ptr<logevent::InboundSecretMessage> message);
+
+  void on_inbound_save_message_finish(uint64 state_id);
+  void on_inbound_save_changes_finish(uint64 state_id);
+  void inbound_loop(InboundMessageState *state, uint64 state_id);
+
+  // OutboundMessage
+  struct OutboundMessageState {
+    std::unique_ptr<logevent::OutboundSecretMessage> message;
+
+    Promise<> outer_send_message_finish;
+    Promise<> send_message_finish;
+
+    bool save_changes_finish_flag = false;
+    bool send_message_finish_flag = false;
+    bool ack_flag = false;
+
+    uint64 net_query_id = 0;
+    NetQueryRef net_query_ref;
+    bool net_query_may_fail = false;
+
+    std::function<void(Promise<>)> send_result_;
+  };
+  std::map<uint64, uint64> random_id_to_outbound_message_state_token_;
+  std::map<int32, uint64> out_seq_no_to_outbound_message_state_token_;
+
+  Container<OutboundMessageState> outbound_message_states_;
+
+  NetQueryRef set_typing_query_;
+
+  enum SendFlag {
+    None = 0,
+    External = 1,
+    Push = 2,
+  };
+  void send_action(tl_object_ptr<secret_api::DecryptedMessageAction> action, int32 flags, Promise<> promise);
+
+  void send_message_impl(tl_object_ptr<secret_api::DecryptedMessage> message,
+                         tl_object_ptr<telegram_api::InputEncryptedFile> file, int32 flags, Promise<> promise);
+
+  void do_outbound_message_impl(std::unique_ptr<logevent::OutboundSecretMessage>, Promise<> promise);
+  Result<BufferSlice> create_encrypted_message(int32 layer, int32 my_in_seq_no, int32 my_out_seq_no,
+                                               tl_object_ptr<secret_api::DecryptedMessage> &message);
+
+  NetQueryPtr create_net_query(const logevent::OutboundSecretMessage &message);
+
+  void outbound_resend(uint64 state_id);
+  Status outbound_rewrite_with_empty(uint64 state_id);
+  void on_outbound_send_message_start(uint64 state_id);
+  void on_outbound_send_message_result(NetQueryPtr query, Promise<NetQueryPtr> resend_promise);
+  void on_outbound_send_message_error(uint64 state_id, Status error, Promise<NetQueryPtr> resend_promise);
+  void on_outbound_send_message_finish(uint64 state_id);
+  void on_outbound_save_changes_finish(uint64 state_id);
+  void on_outbound_ack(uint64 state_id);
+  void on_outbound_outer_send_message_promise(uint64 state_id, Promise<> promise);
+  void outbound_loop(OutboundMessageState *state, uint64 state_id);
+
+  // DiscardEncryption
+  void on_fatal_error(Status status);
+  void do_close_chat_impl(std::unique_ptr<logevent::CloseSecretChat> event);
+  void on_discard_encryption_result(NetQueryPtr result);
+
+  // Other
+  template <class T>
+  Status save_common_info(T &update);
+
+  int32 current_layer() const {
+    int32 layer = MY_LAYER;
+    if (config_state_.his_layer < layer) {
+      layer = config_state_.his_layer;
+    }
+    if (layer < DEFAULT_LAYER) {
+      layer = DEFAULT_LAYER;
+    }
+    return layer;
+  }
+
+  void ask_on_binlog_replay_finish();
+
+  void check_status(Status status);
+  void start_up() override;
+  void loop() override;
+  Status do_loop();
+  void tear_down() override;
+
+  void on_result_resendable(NetQueryPtr net_query, Promise<NetQueryPtr> promise) override;
+
+  Status run_auth();
+  void run_pfs();
+  void run_fill_gaps();
+  void on_send_message_ack(int64 random_id);
+  Status on_delete_messages(const vector<int64> &random_ids);
+  Status on_flush_history(int32 last_message_id);
+
+  telegram_api::object_ptr<telegram_api::inputUser> get_input_user();
+  telegram_api::object_ptr<telegram_api::inputEncryptedChat> get_input_chat();
+
+  Status on_update_chat(telegram_api::encryptedChatRequested &update) TD_WARN_UNUSED_RESULT;
+  Status on_update_chat(telegram_api::encryptedChatEmpty &update) TD_WARN_UNUSED_RESULT;
+  Status on_update_chat(telegram_api::encryptedChatWaiting &update) TD_WARN_UNUSED_RESULT;
+  Status on_update_chat(telegram_api::encryptedChat &update) TD_WARN_UNUSED_RESULT;
+  Status on_update_chat(telegram_api::encryptedChatDiscarded &update) TD_WARN_UNUSED_RESULT;
+
+  Status on_update_chat(NetQueryPtr query) TD_WARN_UNUSED_RESULT;
+  Status on_update_chat(telegram_api::object_ptr<telegram_api::EncryptedChat> chat) TD_WARN_UNUSED_RESULT;
+
+  void on_promise_error(Status error, string desc);
+
+  void get_dh_config();
+  Status on_dh_config(NetQueryPtr query) TD_WARN_UNUSED_RESULT;
+  void on_dh_config(telegram_api::messages_dhConfigNotModified &dh_not_modified);
+  void on_dh_config(telegram_api::messages_dhConfig &dh);
+
+  void do_create_chat_impl(std::unique_ptr<logevent::CreateSecretChat> event);
+
+  SecretChatId get_secret_chat_id() {
+    return SecretChatId(auth_state_.id);
+  }
+  UserId get_user_id() {
+    return UserId(auth_state_.user_id);
+  }
+  void send_update_ttl(int32 ttl);
+  void send_update_secret_chat();
+  void calc_key_hash();
+
+  friend inline StringBuilder &operator<<(StringBuilder &sb, const SecretChatActor::SeqNoState &state) {
+    return sb << "[" << tag("my_in_seq_no", state.my_in_seq_no) << tag("my_out_seq_no", state.my_out_seq_no)
+              << tag("his_in_seq_no", state.his_in_seq_no) << "]";
+  }
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/SecretChatDb.cpp b/libs/tdlib/td/td/telegram/SecretChatDb.cpp
new file mode 100644
index 0000000000..0b3558c9fd
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/SecretChatDb.cpp
@@ -0,0 +1,15 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/SecretChatDb.h"
+
+namespace td {
+
+SecretChatDb::SecretChatDb(std::shared_ptr<KeyValueSyncInterface> pmc, int32 chat_id)
+    : pmc_(std::move(pmc)), chat_id_(chat_id) {
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/SecretChatDb.h b/libs/tdlib/td/td/telegram/SecretChatDb.h
new file mode 100644
index 0000000000..df971777a2
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/SecretChatDb.h
@@ -0,0 +1,50 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/db/KeyValueSyncInterface.h"
+#include "td/db/Pmc.h"
+#include "td/db/SqliteDb.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/Status.h"
+#include "td/utils/tl_helpers.h"
+
+#include <memory>
+
+namespace td {
+class SecretChatDb {
+ public:
+  SecretChatDb(std::shared_ptr<KeyValueSyncInterface> pmc, int32 chat_id);
+
+  // TODO: some other interface for PFS
+  // two keys should be supported
+  template <class ValueT>
+  void set_value(const ValueT &data) {
+    auto key = PSTRING() << "secret" << chat_id_ << ValueT::key();
+    pmc_->set(std::move(key), serialize(data));
+  }
+  template <class ValueT>
+  void erase_value(const ValueT &data) {
+    auto key = PSTRING() << "secret" << chat_id_ << ValueT::key();
+    pmc_->erase(std::move(key));
+  }
+  template <class ValueT>
+  Result<ValueT> get_value() {
+    ValueT value;
+    auto key = PSTRING() << "secret" << chat_id_ << ValueT::key();
+    auto value_str = pmc_->get(std::move(key));
+    TRY_STATUS(unserialize(value, value_str));
+    return std::move(value);
+  }
+
+ private:
+  std::shared_ptr<KeyValueSyncInterface> pmc_;
+  int32 chat_id_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/SecretChatId.h b/libs/tdlib/td/td/telegram/SecretChatId.h
new file mode 100644
index 0000000000..b0e9d6277d
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/SecretChatId.h
@@ -0,0 +1,66 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/StringBuilder.h"
+
+#include <functional>
+#include <type_traits>
+
+namespace td {
+
+enum class SecretChatState : int32 { Unknown = -1, Waiting, Active, Closed };
+
+class SecretChatId {
+  int32 id = 0;
+
+ public:
+  SecretChatId() = default;
+
+  explicit SecretChatId(int32 chat_id) : id(chat_id) {
+  }
+  template <class T, typename = std::enable_if_t<std::is_convertible<T, int32>::value>>
+  SecretChatId(T chat_id) = delete;
+
+  bool is_valid() const {
+    return id != 0;
+  }
+
+  int32 get() const {
+    return id;
+  }
+
+  bool operator==(const SecretChatId &other) const {
+    return id == other.id;
+  }
+
+  bool operator!=(const SecretChatId &other) const {
+    return id != other.id;
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    storer.store_int(id);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    id = parser.fetch_int();
+  }
+};
+
+struct SecretChatIdHash {
+  std::size_t operator()(SecretChatId secret_chat_id) const {
+    return std::hash<int32>()(secret_chat_id.get());
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &string_builder, SecretChatId secret_chat_id) {
+  return string_builder << "secret chat " << secret_chat_id.get();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/SecretChatsManager.cpp b/libs/tdlib/td/td/telegram/SecretChatsManager.cpp
new file mode 100644
index 0000000000..2ba15119ee
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/SecretChatsManager.cpp
@@ -0,0 +1,561 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/SecretChatsManager.h"
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/ConfigShared.h"
+#include "td/telegram/ContactsManager.h"
+#include "td/telegram/DhCache.h"
+#include "td/telegram/logevent/SecretChatEvent.h"
+#include "td/telegram/MessageId.h"
+#include "td/telegram/MessagesManager.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+#include "td/telegram/SequenceDispatcher.h"
+#include "td/telegram/Td.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/telegram_api.hpp"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Random.h"
+#include "td/utils/Status.h"
+#include "td/utils/Time.h"
+
+#include <memory>
+
+namespace td {
+//
+// qts and seq_no
+// Each EncryptedMessage (update_message) has qts.
+// Such updates must be handled in order of qts
+//
+// Qts should be handled on level of SecretChatsManager
+// 1. Each update can be received by SecretChatsManager multiple times.
+// 2. Each update should be sent to SecretChatActor only once. (Thought SecretChatActor mustn't rely it)
+// 3. Updates must be send in order of qts, without gaps.
+// 4. SecretChatActor must notify SecretChatManager when update is processed (saved in db)
+// 5. Only after all updates <= qts are processed by SecretChatActor, UpdatesManager should be
+// notified about new qts.
+//
+// seq_no
+// 1.
+// x_in = 0 if we initiated secret chat.
+// x_in = 1 if other client initiated secret chat
+// x_out = 1 - x_in
+// 2. Send:
+// in_seq_no = my_in_seq_no * 2 + x_in
+// out_seq_no = my_out_seq_no * 2 + x_out
+// my_out_seq_no++;
+//
+// 3. Receive
+// fail_if (in_seq_no % 2 != (1 - x_in)), in_seq_no /= 2.
+// fail_if (out_seq_no % 2 != x_out), out_seq_no /= 2.
+// drop_if (out_seq_no < my_in_seq_no)
+// handle_gap_if(out_seq_no > my_in_seq_no)
+// my_in_seq_no++;
+//
+// fail_if(in_seq_no < his_in_seq_no)
+// his_in_seq_no = in_seq_no
+// fail_if(my_out_seq_no < his_in_seq_no)
+//
+// 4. Preventing gaps.
+// All messages must be sent in order of out_seq_no
+// Messages of older layer have imaginary seq_no = -1
+// a. TODO use invokeAfter.
+// b. Just don't send next message before server accepted previous one.
+//
+// 5. Handling gaps.
+// TODO
+// Just fail chat.
+//
+//
+//
+
+SecretChatsManager::SecretChatsManager(ActorShared<> parent) : parent_(std::move(parent)) {
+}
+
+void SecretChatsManager::start_up() {
+  if (!G()->parameters().use_secret_chats) {
+    dummy_mode_ = true;
+    return;
+  }
+  // TODO: use db wrapper
+  auto pmc = G()->td_db()->get_binlog_pmc();
+  auto qts_str = pmc->get("updates.qts");
+  if (!qts_str.empty()) {
+    init_qts(to_integer<int32>(qts_str));
+  }
+
+  class StateCallback : public StateManager::Callback {
+   public:
+    explicit StateCallback(ActorId<SecretChatsManager> parent) : parent_(std::move(parent)) {
+    }
+    bool on_online(bool online_flag) override {
+      send_closure(parent_, &SecretChatsManager::on_online, online_flag);
+      return parent_.is_alive();
+    }
+
+   private:
+    ActorId<SecretChatsManager> parent_;
+  };
+  send_closure(G()->state_manager(), &StateManager::add_callback, make_unique<StateCallback>(actor_id(this)));
+}
+
+void SecretChatsManager::init_qts(int qts) {
+  if (dummy_mode_ || close_flag_) {
+    return;
+  }
+  has_qts_ = true;
+  qts_manager_.init(qts);
+  LOG(INFO) << "Init secret chats qts " << tag("qts", qts);
+}
+
+void SecretChatsManager::update_qts(int qts) {
+  if (dummy_mode_ || close_flag_ || qts < 0) {
+    return;
+  }
+  LOG(INFO) << "update qts: " << qts;
+  add_qts(qts).set_value(Unit());
+  has_qts_ = true;
+  LOG(INFO) << "Update secret chats qts " << tag("qts", qts);
+}
+
+void SecretChatsManager::create_chat(int32 user_id, int64 user_access_hash, Promise<SecretChatId> promise) {
+  int32 random_id;
+  ActorId<SecretChatActor> actor;
+  do {
+    random_id = Random::secure_int32() & 0x7fffffff;
+    actor = create_chat_actor(random_id);
+  } while (actor.empty());
+  send_closure(actor, &SecretChatActor::create_chat, user_id, user_access_hash, random_id, std::move(promise));
+}
+
+void SecretChatsManager::cancel_chat(SecretChatId secret_chat_id, Promise<> promise) {
+  auto actor = get_chat_actor(secret_chat_id.get());
+  auto safe_promise = SafePromise<>(std::move(promise), Unit());
+  send_closure(actor, &SecretChatActor::cancel_chat, std::move(safe_promise));
+}
+
+void SecretChatsManager::send_message(SecretChatId secret_chat_id, tl_object_ptr<secret_api::decryptedMessage> message,
+                                      tl_object_ptr<telegram_api::InputEncryptedFile> file, Promise<> promise) {
+  // message->message_ = Random::fast(0, 1) ? string(1, static_cast<char>(0x80)) : "a";
+  auto actor = get_chat_actor(secret_chat_id.get());
+  auto safe_promise = SafePromise<>(std::move(promise), Status::Error(400, "Can't find secret chat"));
+  send_closure(actor, &SecretChatActor::send_message, std::move(message), std::move(file), std::move(safe_promise));
+}
+void SecretChatsManager::send_message_action(SecretChatId secret_chat_id,
+                                             tl_object_ptr<secret_api::SendMessageAction> action) {
+  auto actor = get_chat_actor(secret_chat_id.get());
+  if (actor.empty()) {
+    return;
+  }
+  send_closure(actor, &SecretChatActor::send_message_action, std::move(action));
+}
+void SecretChatsManager::send_read_history(SecretChatId secret_chat_id, int32 date, Promise<> promise) {
+  auto actor = get_chat_actor(secret_chat_id.get());
+  auto safe_promise = SafePromise<>(std::move(promise), Status::Error(400, "Can't find secret chat"));
+  send_closure(actor, &SecretChatActor::send_read_history, date, std::move(safe_promise));
+}
+void SecretChatsManager::send_open_message(SecretChatId secret_chat_id, int64 random_id, Promise<> promise) {
+  auto actor = get_chat_actor(secret_chat_id.get());
+  auto safe_promise = SafePromise<>(std::move(promise), Status::Error(400, "Can't find secret chat"));
+  send_closure(actor, &SecretChatActor::send_open_message, random_id, std::move(safe_promise));
+}
+
+void SecretChatsManager::delete_messages(SecretChatId secret_chat_id, vector<int64> random_ids, Promise<> promise) {
+  auto actor = get_chat_actor(secret_chat_id.get());
+  auto safe_promise = SafePromise<>(std::move(promise), Status::Error(400, "Can't find secret chat"));
+  send_closure(actor, &SecretChatActor::delete_messages, std::move(random_ids), std::move(safe_promise));
+}
+
+void SecretChatsManager::delete_all_messages(SecretChatId secret_chat_id, Promise<> promise) {
+  auto actor = get_chat_actor(secret_chat_id.get());
+  auto safe_promise = SafePromise<>(std::move(promise), Status::Error(400, "Can't find secret chat"));
+  send_closure(actor, &SecretChatActor::delete_all_messages, std::move(safe_promise));
+}
+
+void SecretChatsManager::notify_screenshot_taken(SecretChatId secret_chat_id, Promise<> promise) {
+  auto actor = get_chat_actor(secret_chat_id.get());
+  auto safe_promise = SafePromise<>(std::move(promise), Status::Error(400, "Can't find secret chat"));
+  send_closure(actor, &SecretChatActor::notify_screenshot_taken, std::move(safe_promise));
+}
+
+void SecretChatsManager::send_set_ttl_message(SecretChatId secret_chat_id, int32 ttl, int64 random_id,
+                                              Promise<> promise) {
+  auto actor = get_chat_actor(secret_chat_id.get());
+  auto safe_promise = SafePromise<>(std::move(promise), Status::Error(400, "Can't find secret chat"));
+  send_closure(actor, &SecretChatActor::send_set_ttl_message, ttl, random_id, std::move(safe_promise));
+}
+
+void SecretChatsManager::before_get_difference(int32 qts) {
+  if (dummy_mode_ || close_flag_) {
+    return;
+  }
+  last_get_difference_qts_ = qts;
+  // We will receive all updates later than qts anyway.
+}
+
+void SecretChatsManager::after_get_difference() {
+  if (dummy_mode_ || close_flag_) {
+    return;
+  }
+}
+
+void SecretChatsManager::on_update_chat(tl_object_ptr<telegram_api::updateEncryption> update) {
+  if (dummy_mode_ || close_flag_) {
+    return;
+  }
+  bool chat_requested = update->chat_->get_id() == telegram_api::encryptedChatRequested::ID;
+  pending_chat_updates_.push_back({Timestamp::in(chat_requested ? 1 : 0), std::move(update)});
+  flush_pending_chat_updates();
+}
+
+void SecretChatsManager::do_update_chat(tl_object_ptr<telegram_api::updateEncryption> update) {
+  int32 id = 0;
+  downcast_call(*update->chat_, [&](auto &x) { id = x.id_; });
+
+  send_closure(
+      update->chat_->get_id() == telegram_api::encryptedChatDiscarded::ID ? get_chat_actor(id) : create_chat_actor(id),
+      &SecretChatActor::update_chat, std::move(update->chat_));
+}
+
+void SecretChatsManager::on_update_message(tl_object_ptr<telegram_api::updateNewEncryptedMessage> update,
+                                           bool force_apply) {
+  if (dummy_mode_ || close_flag_) {
+    return;
+  }
+  // UpdatesManager MUST postpone updates during GetDifference
+  auto qts = update->qts_;
+  if (!force_apply) {
+    if (!has_qts_) {
+      LOG(INFO) << "Got update, don't know current qts. Force get_difference";
+      force_get_difference();
+      return;
+    }
+    if (qts <= last_get_difference_qts_) {
+      LOG(WARNING) << "Got updates with " << tag("qts", qts) << " lower or equal than "
+                   << tag("last get difference qts", last_get_difference_qts_);
+      force_get_difference();
+      return;
+    }
+    auto mem_qts = qts_manager_.mem_pts();
+    if (qts <= mem_qts) {
+      LOG(WARNING) << "Duplicated update " << tag("qts", qts) << tag("mem_qts", mem_qts);
+      return;
+    }
+    if (qts != mem_qts + 1) {
+      LOG(WARNING) << "Got gap in qts " << mem_qts << " ... " << qts;
+      force_get_difference();
+      // TODO wait 1 second?
+      return;
+    }
+  }
+
+  auto event = std::make_unique<logevent::InboundSecretMessage>();
+  event->qts = qts;
+  downcast_call(*update->message_, [&](auto &x) {
+    event->chat_id = x.chat_id_;
+    event->date = x.date_;
+    event->encrypted_message = std::move(x.bytes_);
+  });
+  if (update->message_->get_id() == telegram_api::encryptedMessage::ID) {
+    auto message = move_tl_object_as<telegram_api::encryptedMessage>(update->message_);
+    if (message->file_->get_id() == telegram_api::encryptedFile::ID) {
+      auto file = move_tl_object_as<telegram_api::encryptedFile>(message->file_);
+
+      event->file.id = file->id_;
+      event->file.access_hash = file->access_hash_;
+      event->file.size = file->size_;
+      event->file.dc_id = file->dc_id_;
+      event->file.key_fingerprint = file->key_fingerprint_;
+
+      event->has_encrypted_file = true;
+    }
+  }
+  add_inbound_message(std::move(event));
+}
+
+Promise<> SecretChatsManager::add_qts(int32 qts) {
+  auto id = qts_manager_.add_pts(qts);
+  return PromiseCreator::event(self_closure(this, &SecretChatsManager::on_qts_ack, id));
+}
+
+void SecretChatsManager::replay_binlog_event(BinlogEvent &&binlog_event) {
+  auto r_message = logevent::SecretChatEvent::from_buffer_slice(binlog_event.data_as_buffer_slice());
+  LOG_IF(FATAL, r_message.is_error()) << "Failed to deserialize event: " << r_message.error();
+  auto message = r_message.move_as_ok();
+  message->set_logevent_id(binlog_event.id_);
+  LOG(INFO) << "Process binlog event " << *message;
+  switch (message->get_type()) {
+    case logevent::SecretChatEvent::Type::InboundSecretMessage:
+      return replay_inbound_message(std::unique_ptr<logevent::InboundSecretMessage>(
+          static_cast<logevent::InboundSecretMessage *>(message.release())));
+    case logevent::SecretChatEvent::Type::OutboundSecretMessage:
+      return replay_outbound_message(std::unique_ptr<logevent::OutboundSecretMessage>(
+          static_cast<logevent::OutboundSecretMessage *>(message.release())));
+    case logevent::SecretChatEvent::Type::CloseSecretChat:
+      return replay_close_chat(
+          std::unique_ptr<logevent::CloseSecretChat>(static_cast<logevent::CloseSecretChat *>(message.release())));
+    case logevent::SecretChatEvent::Type::CreateSecretChat:
+      return replay_create_chat(
+          std::unique_ptr<logevent::CreateSecretChat>(static_cast<logevent::CreateSecretChat *>(message.release())));
+  }
+  LOG(FATAL) << "Unknown logevent type " << tag("type", format::as_hex(static_cast<int32>(message->get_type())));
+}
+
+void SecretChatsManager::binlog_replay_finish() {
+  binlog_replay_finish_flag_ = true;
+  for (auto &it : id_to_actor_) {
+    send_closure(it.second, &SecretChatActor::binlog_replay_finish);
+  }
+}
+
+void SecretChatsManager::replay_inbound_message(std::unique_ptr<logevent::InboundSecretMessage> message) {
+  LOG(INFO) << "Process inbound secret message " << tag("qts", message->qts);
+  auto actor = get_chat_actor(message->chat_id);
+  send_closure_later(actor, &SecretChatActor::replay_inbound_message, std::move(message));
+}
+void SecretChatsManager::add_inbound_message(std::unique_ptr<logevent::InboundSecretMessage> message) {
+  LOG(INFO) << "Process inbound secret message " << tag("qts", message->qts);
+  message->qts_ack = add_qts(message->qts);
+
+  auto actor = get_chat_actor(message->chat_id);
+  send_closure(actor, &SecretChatActor::add_inbound_message, std::move(message));
+}
+
+void SecretChatsManager::replay_close_chat(std::unique_ptr<logevent::CloseSecretChat> message) {
+  LOG(INFO) << "Process close secret chat " << tag("id", message->chat_id);
+
+  auto actor = get_chat_actor(message->chat_id);
+  send_closure_later(actor, &SecretChatActor::replay_close_chat, std::move(message));
+}
+void SecretChatsManager::replay_create_chat(std::unique_ptr<logevent::CreateSecretChat> message) {
+  LOG(INFO) << "Process create secret chat " << tag("id", message->random_id);
+
+  auto actor = create_chat_actor(message->random_id);
+  send_closure_later(actor, &SecretChatActor::replay_create_chat, std::move(message));
+}
+
+void SecretChatsManager::replay_outbound_message(std::unique_ptr<logevent::OutboundSecretMessage> message) {
+  auto actor = get_chat_actor(message->chat_id);
+  send_closure_later(actor, &SecretChatActor::replay_outbound_message, std::move(message));
+}
+
+void SecretChatsManager::force_get_difference() {
+  LOG(INFO) << "Force get difference";
+  send_closure(G()->td(), &Td::force_get_difference);
+}
+
+ActorId<SecretChatActor> SecretChatsManager::get_chat_actor(int32 id) {
+  return create_chat_actor_impl(id, false);
+}
+
+ActorId<SecretChatActor> SecretChatsManager::create_chat_actor(int32 id) {
+  return create_chat_actor_impl(id, true);
+}
+
+std::unique_ptr<SecretChatActor::Context> SecretChatsManager::make_secret_chat_context(int32 id) {
+  class Context : public SecretChatActor::Context {
+   public:
+    Context(int32 id, ActorShared<SecretChatsManager> parent, std::unique_ptr<SecretChatDb> secret_chat_db)
+        : secret_chat_id_(SecretChatId(id)), parent_(std::move(parent)), secret_chat_db_(std::move(secret_chat_db)) {
+      sequence_dispatcher_ = create_actor<SequenceDispatcher>("SecretChat SequenceDispatcher");
+    }
+    Context(const Context &other) = delete;
+    Context &operator=(const Context &other) = delete;
+    Context(Context &&other) = delete;
+    Context &operator=(Context &&other) = delete;
+    ~Context() override {
+      send_closure(std::move(sequence_dispatcher_), &SequenceDispatcher::close_silent);
+    }
+
+    DhCallback *dh_callback() override {
+      return DhCache::instance();
+    }
+    NetQueryCreator &net_query_creator() override {
+      return G()->net_query_creator();
+    }
+    BinlogInterface *binlog() override {
+      return G()->td_db()->get_binlog();
+    }
+    SecretChatDb *secret_chat_db() override {
+      return secret_chat_db_.get();
+    }
+    std::shared_ptr<DhConfig> dh_config() override {
+      return G()->get_dh_config();
+    }
+    void set_dh_config(std::shared_ptr<DhConfig> dh_config) override {
+      G()->set_dh_config(std::move(dh_config));
+    }
+    void send_net_query(NetQueryPtr query, ActorShared<NetQueryCallback> callback, bool ordered) override {
+      if (ordered) {
+        send_closure(sequence_dispatcher_, &SequenceDispatcher::send_with_callback, std::move(query),
+                     std::move(callback));
+      } else {
+        G()->net_query_dispatcher().dispatch_with_callback(std::move(query), std::move(callback));
+      }
+    }
+
+    bool get_config_option_boolean(const string &name) const override {
+      return G()->shared_config().get_option_boolean(name);
+    }
+
+    int32 unix_time() override {
+      return G()->unix_time();
+    }
+
+    bool close_flag() override {
+      return G()->close_flag();
+    }
+
+    void on_update_secret_chat(int64 access_hash, UserId user_id, SecretChatState state, bool is_outbound, int32 ttl,
+                               int32 date, string key_hash, int32 layer) override {
+      send_closure(G()->contacts_manager(), &ContactsManager::on_update_secret_chat, secret_chat_id_, access_hash,
+                   user_id, state, is_outbound, ttl, date, key_hash, layer);
+    }
+
+    void on_inbound_message(UserId user_id, MessageId message_id, int32 date,
+                            tl_object_ptr<telegram_api::encryptedFile> file,
+                            tl_object_ptr<secret_api::decryptedMessage> message, Promise<> promise) override {
+      send_closure(G()->messages_manager(), &MessagesManager::on_get_secret_message, secret_chat_id_, user_id,
+                   message_id, date, std::move(file), std::move(message), std::move(promise));
+    }
+
+    void on_send_message_error(int64 random_id, Status error, Promise<> promise) override {
+      send_closure(G()->messages_manager(), &MessagesManager::on_send_secret_message_error, random_id, std::move(error),
+                   std::move(promise));
+    }
+
+    void on_send_message_ack(int64 random_id) override {
+      send_closure(G()->messages_manager(), &MessagesManager::on_send_message_get_quick_ack, random_id);
+    }
+    void on_send_message_ok(int64 random_id, MessageId message_id, int32 date,
+                            tl_object_ptr<telegram_api::EncryptedFile> file, Promise<> promise) override {
+      send_closure(G()->messages_manager(), &MessagesManager::on_send_secret_message_success, random_id, message_id,
+                   date, std::move(file), std::move(promise));
+    }
+    void on_delete_messages(std::vector<int64> random_ids, Promise<> promise) override {
+      send_closure(G()->messages_manager(), &MessagesManager::delete_secret_messages, secret_chat_id_,
+                   std::move(random_ids), std::move(promise));
+    }
+    void on_flush_history(MessageId message_id, Promise<> promise) override {
+      send_closure(G()->messages_manager(), &MessagesManager::delete_secret_chat_history, secret_chat_id_, message_id,
+                   std::move(promise));
+    }
+    void on_read_message(int64 random_id, Promise<> promise) override {
+      send_closure(G()->messages_manager(), &MessagesManager::open_secret_message, secret_chat_id_, random_id,
+                   std::move(promise));
+    }
+    void on_screenshot_taken(UserId user_id, MessageId message_id, int32 date, int64 random_id,
+                             Promise<> promise) override {
+      send_closure(G()->messages_manager(), &MessagesManager::on_secret_chat_screenshot_taken, secret_chat_id_, user_id,
+                   message_id, date, random_id, std::move(promise));
+    }
+    void on_set_ttl(UserId user_id, MessageId message_id, int32 date, int32 ttl, int64 random_id,
+                    Promise<> promise) override {
+      send_closure(G()->messages_manager(), &MessagesManager::on_secret_chat_ttl_changed, secret_chat_id_, user_id,
+                   message_id, date, ttl, random_id, std::move(promise));
+    }
+
+   private:
+    SecretChatId secret_chat_id_;
+    ActorOwn<SequenceDispatcher> sequence_dispatcher_;
+    ActorShared<SecretChatsManager> parent_;
+    std::unique_ptr<SecretChatDb> secret_chat_db_;
+  };
+  return std::make_unique<Context>(id, actor_shared(this, id),
+                                   std::make_unique<SecretChatDb>(G()->td_db()->get_binlog_pmc_shared(), id));
+}
+
+ActorId<SecretChatActor> SecretChatsManager::create_chat_actor_impl(int32 id, bool can_be_empty) {
+  if (id == 0) {
+    return Auto();
+  }
+  auto it_flag = id_to_actor_.emplace(id, ActorOwn<SecretChatActor>());
+  if (it_flag.second) {
+    LOG(INFO) << "Create SecretChatActor: " << tag("id", id);
+    it_flag.first->second =
+        create_actor<SecretChatActor>(PSLICE() << "SecretChat " << id, id, make_secret_chat_context(id), can_be_empty);
+    if (binlog_replay_finish_flag_) {
+      send_closure(it_flag.first->second, &SecretChatActor::binlog_replay_finish);
+    }
+    return it_flag.first->second.get();
+  } else {
+    return it_flag.first->second.get();
+  }
+}
+void SecretChatsManager::on_qts_ack(PtsManager::PtsId qts_ack_token) {
+  auto old_qts = qts_manager_.db_pts();
+  auto new_qts = qts_manager_.finish(qts_ack_token);
+  if (old_qts != new_qts) {
+    save_qts();
+  }
+}
+
+void SecretChatsManager::save_qts() {
+  LOG(INFO) << "Save " << tag("qts", qts_manager_.db_pts());
+  send_closure(G()->td(), &Td::update_qts, qts_manager_.db_pts());
+}
+
+void SecretChatsManager::hangup() {
+  close_flag_ = true;
+  if (dummy_mode_) {
+    return stop();
+  }
+  for (auto &it : id_to_actor_) {
+    LOG(INFO) << "Ask close SecretChatActor " << tag("id", it.first);
+    it.second.reset();
+  }
+  if (id_to_actor_.empty()) {
+    stop();
+  }
+}
+
+void SecretChatsManager::hangup_shared() {
+  CHECK(!dummy_mode_);
+  auto token = get_link_token();
+  auto it = id_to_actor_.find(static_cast<int32>(token));
+  if (it != id_to_actor_.end()) {
+    LOG(INFO) << "Close SecretChatActor " << tag("id", it->first);
+    it->second.release();
+    id_to_actor_.erase(it);
+  } else {
+    LOG(FATAL) << "Unknown SecretChatActor hangup " << tag("id", static_cast<int32>(token));
+  }
+  if (close_flag_ && id_to_actor_.empty()) {
+    stop();
+  }
+}
+
+void SecretChatsManager::timeout_expired() {
+  flush_pending_chat_updates();
+}
+
+void SecretChatsManager::flush_pending_chat_updates() {
+  if (close_flag_ || dummy_mode_) {
+    return;
+  }
+  auto it = pending_chat_updates_.begin();
+  while (it != pending_chat_updates_.end() && (it->first.is_in_past() || is_online_)) {
+    do_update_chat(std::move(it->second));
+    it++;
+  }
+  if (it != pending_chat_updates_.end()) {
+    set_timeout_at(it->first.at());
+  }
+  pending_chat_updates_.erase(pending_chat_updates_.begin(), it);
+}
+
+void SecretChatsManager::on_online(bool is_online) {
+  is_online_ = is_online;
+  flush_pending_chat_updates();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/SecretChatsManager.h b/libs/tdlib/td/td/telegram/SecretChatsManager.h
new file mode 100644
index 0000000000..c05af851f4
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/SecretChatsManager.h
@@ -0,0 +1,98 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/SecretChatActor.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/logevent/SecretChatEvent.h"
+#include "td/telegram/PtsManager.h"
+#include "td/telegram/SecretChatId.h"
+
+#include "td/actor/actor.h"
+
+#include "td/db/binlog/BinlogEvent.h"
+
+#include "td/utils/Time.h"
+
+#include <map>
+#include <utility>
+
+namespace td {
+class SecretChatsManager : public Actor {
+ public:
+  explicit SecretChatsManager(ActorShared<> parent);
+  void init_qts(int32 qts);
+  void update_qts(int32 qts);
+  // we can forget all pending_updates after start_get_difference they will be received after this point anyway
+  // It is not necessary, but it will help.
+  void before_get_difference(int32 qts);
+  void after_get_difference();
+
+  // Proxy query to corrensponding SecretChatActor.
+  // Look for more info in SecretChatActor.h
+  void on_update_chat(tl_object_ptr<telegram_api::updateEncryption> update);
+  void on_update_message(tl_object_ptr<telegram_api::updateNewEncryptedMessage> update, bool force_apply);
+
+  void create_chat(int32 user_id, int64 user_access_hash, Promise<SecretChatId> promise);
+  void cancel_chat(SecretChatId, Promise<> promise);
+  void send_message(SecretChatId secret_chat_id, tl_object_ptr<secret_api::decryptedMessage> message,
+                    tl_object_ptr<telegram_api::InputEncryptedFile> file, Promise<> promise);
+  void send_message_action(SecretChatId secret_chat_id, tl_object_ptr<secret_api::SendMessageAction> action);
+  void send_read_history(SecretChatId secret_chat_id, int32 date, Promise<> promise);
+  void send_open_message(SecretChatId secret_chat_id, int64 random_id, Promise<> promise);
+  void delete_messages(SecretChatId secret_chat_id, vector<int64> random_ids, Promise<> promise);
+  void delete_all_messages(SecretChatId secret_chat_id, Promise<> promise);
+  void notify_screenshot_taken(SecretChatId secret_chat_id, Promise<> promise);
+  void send_set_ttl_message(SecretChatId secret_chat_id, int32 ttl, int64 random_id, Promise<> promise);
+
+  // Binlog replay
+  void replay_binlog_event(BinlogEvent &&binlog_event);
+  void binlog_replay_finish();
+
+ private:
+  bool binlog_replay_finish_flag_ = false;
+  bool dummy_mode_ = false;
+  bool close_flag_ = false;
+  bool has_qts_ = false;
+  ActorShared<> parent_;
+  std::map<int32, ActorOwn<SecretChatActor>> id_to_actor_;
+
+  PtsManager qts_manager_;
+  int32 last_get_difference_qts_ = -1;
+
+  bool is_online_{false};
+
+  std::vector<std::pair<Timestamp, telegram_api::object_ptr<telegram_api::updateEncryption>>> pending_chat_updates_;
+  void flush_pending_chat_updates();
+  void do_update_chat(tl_object_ptr<telegram_api::updateEncryption> update);
+
+  void replay_inbound_message(std::unique_ptr<logevent::InboundSecretMessage> message);
+  void add_inbound_message(std::unique_ptr<logevent::InboundSecretMessage> message);
+  void replay_outbound_message(std::unique_ptr<logevent::OutboundSecretMessage> message);
+  void replay_close_chat(std::unique_ptr<logevent::CloseSecretChat> message);
+  void replay_create_chat(std::unique_ptr<logevent::CreateSecretChat> message);
+
+  std::unique_ptr<SecretChatActor::Context> make_secret_chat_context(int32 id);
+  ActorId<SecretChatActor> get_chat_actor(int32 id);
+  ActorId<SecretChatActor> create_chat_actor(int32 id);
+  ActorId<SecretChatActor> create_chat_actor_impl(int32 id, bool can_be_empty);
+  Promise<> add_qts(int32 qts);
+  void on_qts_ack(PtsManager::PtsId qts_ack_token);
+  void save_qts();
+  void force_get_difference();
+
+  void start_up() override;
+  void hangup() override;
+  void hangup_shared() override;
+  void timeout_expired() override;
+
+  void on_online(bool is_online);
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/SecretInputMedia.h b/libs/tdlib/td/td/telegram/SecretInputMedia.h
new file mode 100644
index 0000000000..109343b8f6
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/SecretInputMedia.h
@@ -0,0 +1,30 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/telegram_api.h"
+
+namespace td {
+
+struct SecretInputMedia {
+  tl_object_ptr<telegram_api::InputEncryptedFile> input_file_;
+  tl_object_ptr<secret_api::DecryptedMessageMedia> decrypted_media_;
+
+  SecretInputMedia() = default;
+
+  SecretInputMedia(tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                   tl_object_ptr<secret_api::DecryptedMessageMedia> decrypted_media)
+      : input_file_(std::move(input_file)), decrypted_media_(std::move(decrypted_media)) {
+  }
+
+  bool empty() const {
+    return decrypted_media_ == nullptr;
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/SequenceDispatcher.cpp b/libs/tdlib/td/td/telegram/SequenceDispatcher.cpp
new file mode 100644
index 0000000000..723ebed04b
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/SequenceDispatcher.cpp
@@ -0,0 +1,264 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/SequenceDispatcher.h"
+
+#include "td/telegram/Global.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Status.h"
+
+#include <limits>
+
+namespace td {
+/*** Sequence Dispatcher ***/
+// Sends queries with invokeAfter.
+//
+// Each query has three states Start/Wait/Finish
+//
+// finish_i points to the first not Finish query.
+// next_i points to the next query to be sent.
+//
+// Each query has generation of InvokeAfter chain.
+//
+// When query is send, its generation is set to current chain generation.
+//
+// When query is failed and its generation is equals to current generation we must start new chain:
+// increment the generation and set next_i to finish_i.
+//
+// last_sent_i points to the last sent query in current chain.
+//
+void SequenceDispatcher::send_with_callback(NetQueryPtr query, ActorShared<NetQueryCallback> callback) {
+  cancel_timeout();
+  query->debug("Waiting at SequenceDispatcher");
+  auto query_weak_ref = query.get_weak();
+  data_.push_back(Data{State::Start, std::move(query_weak_ref), std::move(query), std::move(callback), 0, 0.0, 0.0});
+  loop();
+}
+
+void SequenceDispatcher::check_timeout(Data &data) {
+  if (data.state_ != State::Start) {
+    return;
+  }
+  data.query_->total_timeout += data.total_timeout_;
+  data.total_timeout_ = 0;
+  if (data.query_->total_timeout > data.query_->total_timeout_limit) {
+    data.query_->set_error(Status::Error(
+        429, PSLICE() << "Too Many Requests: retry after " << static_cast<int32>(data.last_timeout_ + 0.999)));
+    data.state_ = State::Dummy;
+    try_resend_query(data, std::move(data.query_));
+  }
+}
+
+void SequenceDispatcher::try_resend_query(Data &data, NetQueryPtr query) {
+  size_t pos = &data - &data_[0];
+  CHECK(pos < data_.size());
+  CHECK(data.state_ == State::Dummy);
+  data.state_ = State::Wait;
+  wait_cnt_++;
+  auto token = pos + id_offset_;
+  // TODO: is query is ok, use NetQueryCallback::on_result
+  auto promise = PromiseCreator::lambda([&, self = actor_shared(this, token)](NetQueryPtr query) mutable {
+    if (!query.empty()) {
+      send_closure(std::move(self), &SequenceDispatcher::on_resend_ok, std::move(query));
+    } else {
+      send_closure(std::move(self), &SequenceDispatcher::on_resend_error);
+    }
+  });
+  send_closure(data.callback_, &NetQueryCallback::on_result_resendable, std::move(query), std::move(promise));
+}
+
+SequenceDispatcher::Data &SequenceDispatcher::data_from_token() {
+  auto token = narrow_cast<size_t>(get_link_token());
+  auto pos = token - id_offset_;
+  CHECK(pos < data_.size());
+  auto &data = data_[pos];
+  CHECK(data.state_ == State::Wait);
+  CHECK(wait_cnt_ > 0);
+  wait_cnt_--;
+  data.state_ = State::Dummy;
+  return data;
+}
+
+void SequenceDispatcher::on_resend_ok(NetQueryPtr query) {
+  auto &data = data_from_token();
+  data.query_ = std::move(query);
+  do_resend(data);
+  loop();
+}
+
+void SequenceDispatcher::on_resend_error() {
+  auto &data = data_from_token();
+  do_finish(data);
+  loop();
+}
+
+void SequenceDispatcher::do_resend(Data &data) {
+  CHECK(data.state_ == State::Dummy);
+  data.state_ = State::Start;
+  if (data.generation_ == generation_) {
+    next_i_ = finish_i_;
+    generation_++;
+    last_sent_i_ = std::numeric_limits<size_t>::max();
+  }
+  check_timeout(data);
+}
+
+void SequenceDispatcher::do_finish(Data &data) {
+  CHECK(data.state_ == State::Dummy);
+  data.state_ = State::Finish;
+  if (!parent_.empty()) {
+    send_closure(parent_, &Parent::on_result);
+  }
+}
+
+void SequenceDispatcher::on_result(NetQueryPtr query) {
+  auto &data = data_from_token();
+  size_t pos = &data - &data_[0];
+  CHECK(pos < data_.size());
+
+  if (query->last_timeout != 0) {
+    for (auto i = pos + 1; i < data_.size(); i++) {
+      data_[i].total_timeout_ += query->last_timeout;
+      data_[i].last_timeout_ = query->last_timeout;
+      check_timeout(data_[i]);
+    }
+  }
+
+  if (query->is_error() && (query->error().code() == NetQuery::ResendInvokeAfter ||
+                            (query->error().code() == 400 && query->error().message() == "MSG_WAIT_FAILED"))) {
+    VLOG(net_query) << "Resend " << query;
+    query->resend();
+    query->debug("Waiting at SequenceDispatcher");
+    data.query_ = std::move(query);
+    do_resend(data);
+  } else {
+    try_resend_query(data, std::move(query));
+  }
+  loop();
+}
+
+void SequenceDispatcher::loop() {
+  for (; finish_i_ < data_.size() && data_[finish_i_].state_ == State::Finish; finish_i_++) {
+  }
+  if (next_i_ < finish_i_) {
+    next_i_ = finish_i_;
+  }
+  for (; next_i_ < data_.size() && data_[next_i_].state_ != State::Wait && wait_cnt_ < MAX_SIMULTANEOUS_WAIT;
+       next_i_++) {
+    if (data_[next_i_].state_ == State::Finish) {
+      continue;
+    }
+    NetQueryRef invoke_after;
+    if (last_sent_i_ != std::numeric_limits<size_t>::max() && data_[last_sent_i_].state_ == State::Wait) {
+      invoke_after = data_[last_sent_i_].net_query_ref_;
+    }
+    data_[next_i_].query_->set_invoke_after(invoke_after);
+    data_[next_i_].query_->last_timeout = 0;
+
+    VLOG(net_query) << "Send " << data_[next_i_].query_;
+
+    data_[next_i_].query_->debug("send to Td::send_with_callback");
+    data_[next_i_].query_->set_session_rand(session_rand_);
+    G()->net_query_dispatcher().dispatch_with_callback(std::move(data_[next_i_].query_),
+                                                       actor_shared(this, next_i_ + id_offset_));
+    data_[next_i_].state_ = State::Wait;
+    wait_cnt_++;
+    data_[next_i_].generation_ = generation_;
+    last_sent_i_ = next_i_;
+  }
+
+  try_shrink();
+
+  if (finish_i_ == data_.size() && !parent_.empty()) {
+    set_timeout_in(5);
+  }
+}
+
+void SequenceDispatcher::try_shrink() {
+  if (finish_i_ * 2 > data_.size() && data_.size() > 5) {
+    CHECK(finish_i_ <= next_i_);
+    data_.erase(data_.begin(), data_.begin() + finish_i_);
+    next_i_ -= finish_i_;
+    if (last_sent_i_ != std::numeric_limits<size_t>::max()) {
+      if (last_sent_i_ >= finish_i_) {
+        last_sent_i_ -= finish_i_;
+      } else {
+        last_sent_i_ = std::numeric_limits<size_t>::max();
+      }
+    }
+    id_offset_ += finish_i_;
+    finish_i_ = 0;
+  }
+}
+
+void SequenceDispatcher::timeout_expired() {
+  if (finish_i_ != data_.size()) {
+    return;
+  }
+  CHECK(!parent_.empty());
+  set_timeout_in(1);
+  LOG(DEBUG) << "SequenceDispatcher ready to close";
+  send_closure(parent_, &Parent::ready_to_close);
+}
+
+void SequenceDispatcher::hangup() {
+  stop();
+}
+
+void SequenceDispatcher::tear_down() {
+  for (auto &data : data_) {
+    if (data.query_.empty()) {
+      continue;
+    }
+    data.state_ = State::Dummy;
+    data.query_->set_error(Status::Error(500, "Internal Server Error: closing"));
+    do_finish(data);
+  }
+}
+
+void SequenceDispatcher::close_silent() {
+  for (auto &data : data_) {
+    if (!data.query_.empty()) {
+      data.query_->clear();
+    }
+  }
+  stop();
+}
+
+/*** MultiSequenceDispatcher ***/
+void MultiSequenceDispatcher::send_with_callback(NetQueryPtr query, ActorShared<NetQueryCallback> callback,
+                                                 uint64 sequence_id) {
+  CHECK(sequence_id != 0);
+  auto it_ok = dispatchers_.emplace(sequence_id, Data{0, ActorOwn<SequenceDispatcher>()});
+  auto &data = it_ok.first->second;
+  if (it_ok.second) {
+    LOG(DEBUG) << "Create SequenceDispatcher" << sequence_id;
+    data.dispatcher_ = create_actor<SequenceDispatcher>("sequence dispatcher", actor_shared(this, sequence_id));
+  }
+  data.cnt_++;
+  query->debug(PSTRING() << "send to SequenceDispatcher " << tag("sequence_id", sequence_id));
+  send_closure(data.dispatcher_, &SequenceDispatcher::send_with_callback, std::move(query), std::move(callback));
+}
+
+void MultiSequenceDispatcher::on_result() {
+  auto it = dispatchers_.find(get_link_token());
+  CHECK(it != dispatchers_.end());
+  it->second.cnt_--;
+}
+
+void MultiSequenceDispatcher::ready_to_close() {
+  auto it = dispatchers_.find(get_link_token());
+  CHECK(it != dispatchers_.end());
+  if (it->second.cnt_ == 0) {
+    LOG(DEBUG) << "Close SequenceDispatcher " << get_link_token();
+    dispatchers_.erase(it);
+  }
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/SequenceDispatcher.h b/libs/tdlib/td/td/telegram/SequenceDispatcher.h
new file mode 100644
index 0000000000..5ce46068aa
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/SequenceDispatcher.h
@@ -0,0 +1,86 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Random.h"
+
+#include <limits>
+#include <unordered_map>
+
+namespace td {
+class SequenceDispatcher : public NetQueryCallback {
+ public:
+  class Parent : public Actor {
+   public:
+    virtual void ready_to_close() = 0;
+    virtual void on_result() = 0;
+  };
+  SequenceDispatcher() = default;
+  explicit SequenceDispatcher(ActorShared<Parent> parent) : parent_(std::move(parent)) {
+  }
+  void send_with_callback(NetQueryPtr query, ActorShared<NetQueryCallback> callback);
+  void on_result(NetQueryPtr query) override;
+  void close_silent();
+
+ private:
+  enum class State { Start, Wait, Finish, Dummy };
+  struct Data {
+    State state_;
+    NetQueryRef net_query_ref_;
+    NetQueryPtr query_;
+    ActorShared<NetQueryCallback> callback_;
+    uint64 generation_;
+    double total_timeout_;
+    double last_timeout_;
+  };
+
+  ActorShared<Parent> parent_;
+  size_t id_offset_ = 1;
+  std::vector<Data> data_;
+  size_t finish_i_ = 0;  // skip state_ == State::Finish
+  size_t next_i_ = 0;
+  size_t last_sent_i_ = std::numeric_limits<size_t>::max();
+  uint64 generation_ = 1;
+  uint32 session_rand_ = Random::secure_int32();
+
+  static constexpr int32 MAX_SIMULTANEOUS_WAIT = 10;
+  uint32 wait_cnt_ = 0;
+
+  void check_timeout(Data &data);
+
+  void try_resend_query(Data &data, NetQueryPtr query);
+  Data &data_from_token();
+  void on_resend_ok(NetQueryPtr query);
+  void on_resend_error();
+  void do_resend(Data &data);
+  void do_finish(Data &data);
+
+  void loop() override;
+  void try_shrink();
+
+  void timeout_expired() override;
+  void hangup() override;
+  void tear_down() override;
+};
+
+class MultiSequenceDispatcher : public SequenceDispatcher::Parent {
+ public:
+  void send_with_callback(NetQueryPtr query, ActorShared<NetQueryCallback> callback, uint64 sequence_id);
+
+ private:
+  struct Data {
+    int32 cnt_;
+    ActorOwn<SequenceDispatcher> dispatcher_;
+  };
+  std::unordered_map<uint64, Data> dispatchers_;
+  void on_result() override;
+  void ready_to_close() override;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/StateManager.cpp b/libs/tdlib/td/td/telegram/StateManager.cpp
new file mode 100644
index 0000000000..6777f44154
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/StateManager.cpp
@@ -0,0 +1,176 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/StateManager.h"
+
+#include "td/actor/PromiseFuture.h"
+#include "td/actor/SleepActor.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Time.h"
+
+namespace td {
+void StateManager::inc_connect() {
+  auto &cnt = get_link_token() == 1 ? connect_cnt_ : connect_proxy_cnt_;
+  cnt++;
+  if (cnt == 1) {
+    loop();
+  }
+}
+void StateManager::dec_connect() {
+  auto &cnt = get_link_token() == 1 ? connect_cnt_ : connect_proxy_cnt_;
+  CHECK(cnt > 0);
+  cnt--;
+  if (cnt == 0) {
+    loop();
+  }
+}
+
+void StateManager::on_synchronized(bool is_synchronized) {
+  if (sync_flag_ != is_synchronized) {
+    sync_flag_ = is_synchronized;
+    loop();
+  }
+  if (sync_flag_ && !was_sync_) {
+    was_sync_ = true;
+    auto promises = std::move(wait_first_sync_);
+    reset_to_empty(wait_first_sync_);
+    for (auto &promise : promises) {
+      promise.set_value(Unit());
+    }
+  }
+}
+
+void StateManager::on_network(NetType new_network_type) {
+  do_on_network(new_network_type, true /*inc_generation*/);
+}
+void StateManager::do_on_network(NetType new_network_type, bool inc_generation) {
+  bool new_network_flag = new_network_type != NetType::None;
+  if (network_flag_ != new_network_flag) {
+    network_flag_ = new_network_flag;
+    loop();
+  }
+  network_type_ = new_network_type;
+  if (inc_generation) {
+    network_generation_++;
+  }
+  notify_flags(NetworkFlag);
+}
+
+void StateManager::on_online(bool is_online) {
+  online_flag_ = is_online;
+  notify_flags(OnlineFlag);
+}
+
+void StateManager::on_proxy(bool use_proxy) {
+  use_proxy_ = use_proxy;
+  on_network(network_type_);
+  loop();
+}
+
+void StateManager::add_callback(unique_ptr<Callback> callback) {
+  if (callback->on_network(network_type_, network_generation_) && callback->on_online(online_flag_) &&
+      callback->on_state(get_real_state())) {
+    callbacks_.push_back(std::move(callback));
+  }
+}
+void StateManager::wait_first_sync(Promise<> promise) {
+  if (was_sync_) {
+    return promise.set_value(Unit());
+  }
+  wait_first_sync_.push_back(std::move(promise));
+}
+
+void StateManager::close() {
+  stop();
+}
+
+StateManager::State StateManager::get_real_state() const {
+  if (!network_flag_) {
+    return State::WaitingForNetwork;
+  }
+  if (!connect_cnt_) {
+    if (use_proxy_ && !connect_proxy_cnt_) {
+      return State::ConnectingToProxy;
+    }
+    return State::Connecting;
+  }
+  if (!sync_flag_) {
+    return State::Updating;
+  }
+  return State::Ready;
+}
+
+void StateManager::notify_flags(int32 flags) {
+  for (auto it = callbacks_.begin(); it != callbacks_.end();) {
+    bool ok = true;
+    if (flags & OnlineFlag) {
+      ok &= (*it)->on_online(online_flag_);
+    }
+    if (flags & StateFlag) {
+      ok &= (*it)->on_state(flush_state_);
+    }
+    if (flags & NetworkFlag) {
+      ok &= (*it)->on_network(network_type_, network_generation_);
+    }
+    if (ok) {
+      ++it;
+    } else {
+      it = callbacks_.erase(it);
+    }
+  }
+}
+
+void StateManager::on_network_soft() {
+  if (network_type_ == NetType::Unknown) {
+    LOG(INFO) << "Auto set net_type = Other";
+    do_on_network(NetType::Other, false /*inc_generation*/);
+  }
+}
+
+void StateManager::start_up() {
+  create_actor<SleepActor>("SleepActor", 1, PromiseCreator::event(self_closure(this, &StateManager::on_network_soft)))
+      .release();
+  loop();
+}
+
+void StateManager::loop() {
+  auto now = Time::now();
+  auto state = get_real_state();
+  if (state != pending_state_) {
+    pending_state_ = state;
+    if (!has_timestamp_) {
+      pending_timestamp_ = now;
+      has_timestamp_ = true;
+    }
+  }
+  if (pending_state_ != flush_state_) {
+    double delay = 0;
+    if (flush_state_ != State::Empty) {
+      if (static_cast<int32>(pending_state_) > static_cast<int32>(flush_state_)) {
+        delay = UP_DELAY;
+      } else {
+        delay = DOWN_DELAY;
+      }
+      if (network_type_ == NetType::Unknown) {
+        delay = 0;
+      }
+    }
+
+    CHECK(has_timestamp_);
+    if (now >= pending_timestamp_ + delay) {
+      has_timestamp_ = false;
+      flush_state_ = pending_state_;
+      notify_flags(StateFlag);
+    } else {
+      set_timeout_at(pending_timestamp_ + delay);
+    }
+  } else {
+    has_timestamp_ = false;
+  }
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/StateManager.h b/libs/tdlib/td/td/telegram/StateManager.h
new file mode 100644
index 0000000000..cbe24c22d8
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/StateManager.h
@@ -0,0 +1,134 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/net/NetType.h"
+
+#include "td/utils/common.h"
+
+namespace td {
+class StateManager final : public Actor {
+ public:
+  enum class State : int32 { WaitingForNetwork, ConnectingToProxy, Connecting, Updating, Ready, Empty };
+
+  class Callback {
+   public:
+    Callback() = default;
+    Callback(const Callback &) = delete;
+    Callback &operator=(const Callback &) = delete;
+    virtual ~Callback() = default;
+    virtual bool on_state(State state) {
+      return true;
+    }
+    virtual bool on_network(NetType network_type, uint32 generation) {
+      return true;
+    }
+    virtual bool on_online(bool is_online) {
+      return true;
+    }
+  };
+
+  void on_synchronized(bool is_synchronized);
+
+  void on_network(NetType new_network_type);
+
+  void on_online(bool is_online);
+
+  void on_proxy(bool use_proxy);
+
+  void add_callback(unique_ptr<Callback> net_callback);
+
+  void wait_first_sync(Promise<> promise);
+
+  void close();
+
+  class ConnectionToken {
+   public:
+    ConnectionToken() = default;
+    explicit ConnectionToken(ActorShared<StateManager> state_manager) : state_manager_(std::move(state_manager)) {
+    }
+    ConnectionToken(const ConnectionToken &) = delete;
+    ConnectionToken &operator=(const ConnectionToken &) = delete;
+    ConnectionToken(ConnectionToken &&) = default;
+    ConnectionToken &operator=(ConnectionToken &&other) {
+      reset();
+      state_manager_ = std::move(other.state_manager_);
+      return *this;
+    }
+    ~ConnectionToken() {
+      reset();
+    }
+
+    void reset() {
+      if (!state_manager_.empty()) {
+        send_closure(state_manager_, &StateManager::dec_connect);
+        state_manager_.reset();
+      }
+    }
+
+    bool empty() const {
+      return state_manager_.empty();
+    }
+
+   private:
+    ActorShared<StateManager> state_manager_;
+  };
+
+  static ConnectionToken connection(ActorId<StateManager> state_manager) {
+    return connection_impl(state_manager, 1);
+  }
+  static ConnectionToken connection_proxy(ActorId<StateManager> state_manager) {
+    return connection_impl(state_manager, 2);
+  }
+
+ private:
+  uint32 connect_cnt_ = 0;
+  uint32 connect_proxy_cnt_ = 0;
+  bool sync_flag_ = true;
+  bool network_flag_ = true;
+  NetType network_type_ = NetType::Unknown;
+  uint32 network_generation_ = 1;
+  bool online_flag_ = false;
+  bool use_proxy_ = false;
+
+  static constexpr double UP_DELAY = 0.05;
+  static constexpr double DOWN_DELAY = 0.3;
+
+  State pending_state_ = State::Empty;
+  bool has_timestamp_ = false;
+  double pending_timestamp_ = 0;
+  State flush_state_ = State::Empty;
+
+  vector<unique_ptr<Callback>> callbacks_;
+
+  bool was_sync_ = false;
+  std::vector<Promise<>> wait_first_sync_;
+
+  void inc_connect();
+  void dec_connect();
+
+  enum Flags { OnlineFlag = 1, StateFlag = 2, NetworkFlag = 4 };
+  void notify_flags(int32 flags);
+
+  void start_up() override;
+  void loop() override;
+
+  void on_network_soft();
+  void do_on_network(NetType new_network_type, bool inc_generation);
+
+  State get_real_state() const;
+
+  static ConnectionToken connection_impl(ActorId<StateManager> state_manager, int mode) {
+    auto actor = ActorShared<StateManager>(state_manager, mode);
+    send_closure(actor, &StateManager::inc_connect);
+    return ConnectionToken(std::move(actor));
+  }
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/StickersManager.cpp b/libs/tdlib/td/td/telegram/StickersManager.cpp
new file mode 100644
index 0000000000..8606d0d032
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/StickersManager.cpp
@@ -0,0 +1,4189 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/StickersManager.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/MultiPromise.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/AccessRights.h"
+#include "td/telegram/AuthManager.h"
+#include "td/telegram/ContactsManager.h"
+#include "td/telegram/DialogId.h"
+#include "td/telegram/DocumentsManager.h"
+#include "td/telegram/files/FileManager.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/logevent/LogEvent.h"
+#include "td/telegram/MessagesManager.h"
+#include "td/telegram/misc.h"
+#include "td/telegram/StickersManager.hpp"
+#include "td/telegram/Td.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Random.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Time.h"
+#include "td/utils/tl_helpers.h"
+
+#include <algorithm>
+#include <type_traits>
+#include <unordered_set>
+
+namespace td {
+
+class GetAllStickersQuery : public Td::ResultHandler {
+  bool is_masks_;
+
+ public:
+  void send(bool is_masks, int32 hash) {
+    is_masks_ = is_masks;
+    if (is_masks) {
+      send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_getMaskStickers(hash))));
+    } else {
+      send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_getAllStickers(hash))));
+    }
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    static_assert(std::is_same<telegram_api::messages_getMaskStickers::ReturnType,
+                               telegram_api::messages_getAllStickers::ReturnType>::value,
+                  "");
+    auto result_ptr = fetch_result<telegram_api::messages_getAllStickers>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(DEBUG) << "Receive result for get all " << (is_masks_ ? "masks" : "stickers") << ": " << to_string(ptr);
+    td->stickers_manager_->on_get_installed_sticker_sets(is_masks_, std::move(ptr));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for get all stickers: " << status;
+    td->stickers_manager_->on_get_installed_sticker_sets_failed(is_masks_, std::move(status));
+  }
+};
+
+class SearchStickersQuery : public Td::ResultHandler {
+  string emoji_;
+
+ public:
+  void send(string emoji) {
+    emoji_ = std::move(emoji);
+    int32 flags = 0;
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_getStickers(flags, false /*ignored*/, emoji_, ""))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getStickers>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for search stickers: " << to_string(ptr);
+    td->stickers_manager_->on_find_stickers_success(emoji_, std::move(ptr));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for search stickers: " << status;
+    td->stickers_manager_->on_find_stickers_fail(emoji_, std::move(status));
+  }
+};
+
+class GetArchivedStickerSetsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  bool is_masks_;
+
+ public:
+  explicit GetArchivedStickerSetsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(bool is_masks, int64 offset_sticker_set_id, int32 limit) {
+    is_masks_ = is_masks;
+    LOG(INFO) << "Get archived " << (is_masks ? "mask" : "sticker") << " sets from " << offset_sticker_set_id
+              << " with limit " << limit;
+
+    int32 flags = 0;
+    if (is_masks) {
+      flags |= telegram_api::messages_getArchivedStickers::MASKS_MASK;
+    }
+    is_masks_ = is_masks;
+
+    send_query(G()->net_query_creator().create(create_storer(
+        telegram_api::messages_getArchivedStickers(flags, is_masks /*ignored*/, offset_sticker_set_id, limit))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getArchivedStickers>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for GetArchivedStickerSetsQuery " << to_string(ptr);
+    td->stickers_manager_->on_get_archived_sticker_sets(is_masks_, std::move(ptr->sets_), ptr->count_);
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetFeaturedStickerSetsQuery : public Td::ResultHandler {
+ public:
+  void send(int32 hash) {
+    LOG(INFO) << "Get featured sticker sets with hash " << hash;
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_getFeaturedStickers(hash))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getFeaturedStickers>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(DEBUG) << "Receive result for GetFeaturedStickerSetsQuery " << to_string(ptr);
+    td->stickers_manager_->on_get_featured_sticker_sets(std::move(ptr));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->stickers_manager_->on_get_featured_sticker_sets_failed(std::move(status));
+  }
+};
+
+class GetAttachedStickerSetsQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  FileId file_id_;
+
+ public:
+  explicit GetAttachedStickerSetsQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(FileId file_id, tl_object_ptr<telegram_api::InputStickeredMedia> &&input_stickered_media) {
+    file_id_ = file_id;
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_getAttachedStickers(std::move(input_stickered_media)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getAttachedStickers>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->stickers_manager_->on_get_attached_sticker_sets(file_id_, result_ptr.move_as_ok());
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetRecentStickersQuery : public Td::ResultHandler {
+  bool is_attached_;
+
+ public:
+  void send(bool is_attached, int32 hash) {
+    is_attached_ = is_attached;
+    int32 flags = 0;
+    if (is_attached) {
+      flags |= telegram_api::messages_getRecentStickers::ATTACHED_MASK;
+    }
+
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_getRecentStickers(flags, is_attached /*ignored*/, hash))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getRecentStickers>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(DEBUG) << "Receive result for get recent " << (is_attached_ ? "attached " : "")
+               << "stickers: " << to_string(ptr);
+    td->stickers_manager_->on_get_recent_stickers(is_attached_, std::move(ptr));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for get recent stickers: " << status;
+    td->stickers_manager_->on_get_recent_stickers_failed(is_attached_, std::move(status));
+  }
+};
+
+class SaveRecentStickerQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  bool is_attached_;
+
+ public:
+  explicit SaveRecentStickerQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(bool is_attached, tl_object_ptr<telegram_api::InputDocument> &&input_document, bool unsave) {
+    is_attached_ = is_attached;
+
+    int32 flags = 0;
+    if (is_attached) {
+      flags |= telegram_api::messages_saveRecentSticker::ATTACHED_MASK;
+    }
+
+    send_query(G()->net_query_creator().create(create_storer(
+        telegram_api::messages_saveRecentSticker(flags, is_attached /*ignored*/, std::move(input_document), unsave))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_saveRecentSticker>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for save recent sticker: " << result;
+    if (!result) {
+      td->stickers_manager_->reload_recent_stickers(is_attached_, true);
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for save recent sticker: " << status;
+    td->stickers_manager_->reload_recent_stickers(is_attached_, true);
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ClearRecentStickersQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  bool is_attached_;
+
+ public:
+  explicit ClearRecentStickersQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(bool is_attached) {
+    is_attached_ = is_attached;
+
+    int32 flags = 0;
+    if (is_attached) {
+      flags |= telegram_api::messages_clearRecentStickers::ATTACHED_MASK;
+    }
+
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_clearRecentStickers(flags, is_attached /*ignored*/))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_clearRecentStickers>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for clear recent stickers: " << result;
+    if (!result) {
+      td->stickers_manager_->reload_recent_stickers(is_attached_, true);
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for clear recent stickers: " << status;
+    td->stickers_manager_->reload_recent_stickers(is_attached_, true);
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetFavedStickersQuery : public Td::ResultHandler {
+ public:
+  void send(int32 hash) {
+    LOG(INFO) << "Send get favorite stickers request with hash = " << hash;
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_getFavedStickers(hash))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getFavedStickers>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    td->stickers_manager_->on_get_favorite_stickers(std::move(ptr));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for get favorite stickers: " << status;
+    td->stickers_manager_->on_get_favorite_stickers_failed(std::move(status));
+  }
+};
+
+class FaveStickerQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit FaveStickerQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(tl_object_ptr<telegram_api::InputDocument> &&input_document, bool unsave) {
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_faveSticker(std::move(input_document), unsave))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_faveSticker>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for fave sticker: " << result;
+    if (!result) {
+      td->stickers_manager_->reload_favorite_stickers(true);
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for fave sticker: " << status;
+    td->stickers_manager_->reload_favorite_stickers(true);
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ReorderStickerSetsQuery : public Td::ResultHandler {
+  bool is_masks_;
+
+ public:
+  void send(bool is_masks, vector<int64> sticker_set_ids) {
+    is_masks_ = is_masks;
+    int32 flags = 0;
+    if (is_masks) {
+      flags |= telegram_api::messages_reorderStickerSets::MASKS_MASK;
+    }
+    send_query(G()->net_query_creator().create(create_storer(
+        telegram_api::messages_reorderStickerSets(flags, is_masks /*ignored*/, std::move(sticker_set_ids)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_reorderStickerSets>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.move_as_ok();
+    if (!result) {
+      return on_error(id, Status::Error(400, "Result is false"));
+    }
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for ReorderStickerSetsQuery: " << status;
+    td->stickers_manager_->reload_installed_sticker_sets(is_masks_, true);
+  }
+};
+
+class GetStickerSetQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  int64 sticker_set_id_;
+
+ public:
+  explicit GetStickerSetQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int64 sticker_set_id, tl_object_ptr<telegram_api::InputStickerSet> &&input_sticker_set) {
+    sticker_set_id_ = sticker_set_id;
+    LOG(INFO) << "Load sticker set " << sticker_set_id << " from server: " << to_string(input_sticker_set);
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_getStickerSet(std::move(input_sticker_set)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getStickerSet>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    //    LOG(DEBUG) << "Receive result for get sticker set " << to_string(ptr);
+    td->stickers_manager_->on_get_messages_sticker_set(sticker_set_id_, std::move(ptr), true);
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(INFO) << "Receive error for getStickerSet: " << status;
+    td->stickers_manager_->on_load_sticker_set_fail(sticker_set_id_, status);
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SearchStickerSetsQuery : public Td::ResultHandler {
+  string query_;
+
+ public:
+  void send(string query) {
+    query_ = std::move(query);
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_searchStickerSets(0, false /*ignored*/, query_, 0))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_searchStickerSets>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for search sticker sets: " << to_string(ptr);
+    td->stickers_manager_->on_find_sticker_sets_success(query_, std::move(ptr));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for search sticker sets: " << status;
+    td->stickers_manager_->on_find_sticker_sets_fail(query_, std::move(status));
+  }
+};
+
+class InstallStickerSetQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  int64 set_id_;
+  bool is_archived_;
+
+ public:
+  explicit InstallStickerSetQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int64 set_id, tl_object_ptr<telegram_api::InputStickerSet> &&input_set, bool is_archived) {
+    set_id_ = set_id;
+    is_archived_ = is_archived;
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_installStickerSet(std::move(input_set), is_archived))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_installStickerSet>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->stickers_manager_->on_install_sticker_set(set_id_, is_archived_, result_ptr.move_as_ok());
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    CHECK(status.is_error());
+    promise_.set_error(std::move(status));
+  }
+};
+
+class UninstallStickerSetQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  int64 set_id_;
+
+ public:
+  explicit UninstallStickerSetQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int64 set_id, tl_object_ptr<telegram_api::InputStickerSet> &&input_set) {
+    set_id_ = set_id;
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_uninstallStickerSet(std::move(input_set)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_uninstallStickerSet>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.move_as_ok();
+    if (!result) {
+      LOG(WARNING) << "Receive false in result to uninstallStickerSet";
+    } else {
+      td->stickers_manager_->on_uninstall_sticker_set(set_id_);
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    CHECK(status.is_error());
+    promise_.set_error(std::move(status));
+  }
+};
+
+class ReadFeaturedStickerSetsQuery : public Td::ResultHandler {
+ public:
+  void send(vector<int64> sticker_set_ids) {
+    LOG(INFO) << "Read featured sticker sets " << format::as_array(sticker_set_ids);
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_readFeaturedStickers(std::move(sticker_set_ids)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_readFeaturedStickers>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.move_as_ok();
+    (void)result;
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "Receive error for ReadFeaturedStickerSetsQuery: " << status;
+    td->stickers_manager_->reload_featured_sticker_sets(true);
+  }
+};
+
+class UploadStickerFileQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  FileId file_id_;
+
+ public:
+  explicit UploadStickerFileQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(tl_object_ptr<telegram_api::InputPeer> &&input_peer, FileId file_id,
+            tl_object_ptr<telegram_api::InputMedia> &&input_media) {
+    CHECK(input_peer != nullptr);
+    CHECK(input_media != nullptr);
+    file_id_ = file_id;
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_uploadMedia(std::move(input_peer), std::move(input_media)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_uploadMedia>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->stickers_manager_->on_uploaded_sticker_file(file_id_, result_ptr.move_as_ok(), std::move(promise_));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    CHECK(status.is_error());
+    promise_.set_error(std::move(status));
+  }
+};
+
+class CreateNewStickerSetQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit CreateNewStickerSetQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(tl_object_ptr<telegram_api::InputUser> &&input_user, const string &title, const string &short_name,
+            bool is_masks, vector<tl_object_ptr<telegram_api::inputStickerSetItem>> &&input_stickers) {
+    CHECK(input_user != nullptr);
+
+    int32 flags = 0;
+    if (is_masks) {
+      flags |= telegram_api::stickers_createStickerSet::MASKS_MASK;
+    }
+
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::stickers_createStickerSet(
+        flags, false /*ignored*/, std::move(input_user), title, short_name, std::move(input_stickers)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::stickers_createStickerSet>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->stickers_manager_->on_get_messages_sticker_set(0, result_ptr.move_as_ok(), true);
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    CHECK(status.is_error());
+    promise_.set_error(std::move(status));
+  }
+};
+
+class AddStickerToSetQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit AddStickerToSetQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(const string &short_name, tl_object_ptr<telegram_api::inputStickerSetItem> &&input_sticker) {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::stickers_addStickerToSet(
+        make_tl_object<telegram_api::inputStickerSetShortName>(short_name), std::move(input_sticker)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::stickers_addStickerToSet>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->stickers_manager_->on_get_messages_sticker_set(0, result_ptr.move_as_ok(), true);
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    CHECK(status.is_error());
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SetStickerPositionQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit SetStickerPositionQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(tl_object_ptr<telegram_api::InputDocument> &&input_document, int32 position) {
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::stickers_changeStickerPosition(std::move(input_document), position))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::stickers_changeStickerPosition>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->stickers_manager_->on_get_messages_sticker_set(0, result_ptr.move_as_ok(), true);
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    CHECK(status.is_error());
+    promise_.set_error(std::move(status));
+  }
+};
+
+class DeleteStickerFromSetQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit DeleteStickerFromSetQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(tl_object_ptr<telegram_api::InputDocument> &&input_document) {
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::stickers_removeStickerFromSet(std::move(input_document)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::stickers_removeStickerFromSet>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->stickers_manager_->on_get_messages_sticker_set(0, result_ptr.move_as_ok(), true);
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    CHECK(status.is_error());
+    promise_.set_error(std::move(status));
+  }
+};
+
+class StickersManager::StickerListLogEvent {
+ public:
+  vector<FileId> sticker_ids;
+
+  StickerListLogEvent() = default;
+
+  explicit StickerListLogEvent(vector<FileId> sticker_ids) : sticker_ids(std::move(sticker_ids)) {
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    StickersManager *stickers_manager = storer.context()->td().get_actor_unsafe()->stickers_manager_.get();
+    td::store(narrow_cast<int32>(sticker_ids.size()), storer);
+    for (auto sticker_id : sticker_ids) {
+      stickers_manager->store_sticker(sticker_id, false, storer);
+    }
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    StickersManager *stickers_manager = parser.context()->td().get_actor_unsafe()->stickers_manager_.get();
+    int32 size = parser.fetch_int();
+    sticker_ids.resize(size);
+    for (auto &sticker_id : sticker_ids) {
+      sticker_id = stickers_manager->parse_sticker(false, parser);
+    }
+  }
+};
+
+class StickersManager::StickerSetListLogEvent {
+ public:
+  vector<int64> sticker_set_ids;
+
+  StickerSetListLogEvent() = default;
+
+  explicit StickerSetListLogEvent(vector<int64> sticker_set_ids) : sticker_set_ids(std::move(sticker_set_ids)) {
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    StickersManager *stickers_manager = storer.context()->td().get_actor_unsafe()->stickers_manager_.get();
+    td::store(narrow_cast<int32>(sticker_set_ids.size()), storer);
+    for (auto sticker_set_id : sticker_set_ids) {
+      stickers_manager->store_sticker_set_id(sticker_set_id, storer);
+    }
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    StickersManager *stickers_manager = parser.context()->td().get_actor_unsafe()->stickers_manager_.get();
+    int32 size = parser.fetch_int();
+    sticker_set_ids.resize(size);
+    for (auto &sticker_set_id : sticker_set_ids) {
+      stickers_manager->parse_sticker_set_id(sticker_set_id, parser);
+    }
+  }
+};
+
+class StickersManager::UploadStickerFileCallback : public FileManager::UploadCallback {
+ public:
+  void on_upload_ok(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) override {
+    send_closure_later(G()->stickers_manager(), &StickersManager::on_upload_sticker_file, file_id,
+                       std::move(input_file));
+  }
+
+  void on_upload_encrypted_ok(FileId file_id, tl_object_ptr<telegram_api::InputEncryptedFile> input_file) override {
+    UNREACHABLE();
+  }
+
+  void on_upload_error(FileId file_id, Status error) override {
+    send_closure_later(G()->stickers_manager(), &StickersManager::on_upload_sticker_file_error, file_id,
+                       std::move(error));
+  }
+};
+
+StickersManager::StickersManager(Td *td, ActorShared<> parent) : td_(td), parent_(std::move(parent)) {
+  upload_sticker_file_callback_ = std::make_shared<UploadStickerFileCallback>();
+}
+
+void StickersManager::tear_down() {
+  parent_.reset();
+}
+
+tl_object_ptr<td_api::MaskPoint> StickersManager::get_mask_point_object(int32 point) {
+  switch (point) {
+    case 0:
+      return td_api::make_object<td_api::maskPointForehead>();
+    case 1:
+      return td_api::make_object<td_api::maskPointEyes>();
+    case 2:
+      return td_api::make_object<td_api::maskPointMouth>();
+    case 3:
+      return td_api::make_object<td_api::maskPointChin>();
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+tl_object_ptr<td_api::sticker> StickersManager::get_sticker_object(FileId file_id) {
+  if (!file_id.is_valid()) {
+    return nullptr;
+  }
+
+  auto &sticker = stickers_[file_id];
+  CHECK(sticker != nullptr);
+  sticker->is_changed = false;
+
+  auto mask_position = sticker->point >= 0
+                           ? make_tl_object<td_api::maskPosition>(get_mask_point_object(sticker->point),
+                                                                  sticker->x_shift, sticker->y_shift, sticker->scale)
+                           : nullptr;
+
+  const PhotoSize &thumbnail =
+      sticker->sticker_thumbnail.file_id.is_valid() ? sticker->sticker_thumbnail : sticker->message_thumbnail;
+  return make_tl_object<td_api::sticker>(sticker->set_id, sticker->dimensions.width, sticker->dimensions.height,
+                                         sticker->alt, sticker->is_mask, std::move(mask_position),
+                                         get_photo_size_object(td_->file_manager_.get(), &thumbnail),
+                                         td_->file_manager_->get_file_object(file_id));
+}
+
+tl_object_ptr<td_api::stickers> StickersManager::get_stickers_object(const vector<FileId> &sticker_ids) {
+  auto result = make_tl_object<td_api::stickers>();
+  result->stickers_.reserve(sticker_ids.size());
+  for (auto sticker_id : sticker_ids) {
+    result->stickers_.push_back(get_sticker_object(sticker_id));
+  }
+  return result;
+}
+
+tl_object_ptr<td_api::stickerSet> StickersManager::get_sticker_set_object(int64 sticker_set_id) {
+  const StickerSet *sticker_set = get_sticker_set(sticker_set_id);
+  CHECK(sticker_set != nullptr);
+  CHECK(sticker_set->was_loaded);
+
+  std::vector<tl_object_ptr<td_api::sticker>> stickers;
+  std::vector<tl_object_ptr<td_api::stickerEmojis>> emojis;
+  for (auto sticker_id : sticker_set->sticker_ids) {
+    stickers.push_back(get_sticker_object(sticker_id));
+
+    auto it = sticker_set->sticker_emojis_map_.find(sticker_id);
+    if (it == sticker_set->sticker_emojis_map_.end()) {
+      emojis.push_back(Auto());
+    } else {
+      emojis.push_back(make_tl_object<td_api::stickerEmojis>(vector<string>(it->second)));
+    }
+  }
+  return make_tl_object<td_api::stickerSet>(sticker_set->id, sticker_set->title, sticker_set->short_name,
+                                            sticker_set->is_installed && !sticker_set->is_archived,
+                                            sticker_set->is_archived, sticker_set->is_official, sticker_set->is_masks,
+                                            sticker_set->is_viewed, std::move(stickers), std::move(emojis));
+}
+
+tl_object_ptr<td_api::stickerSets> StickersManager::get_sticker_sets_object(int32 total_count,
+                                                                            const vector<int64> &sticker_set_ids,
+                                                                            size_t covers_limit) {
+  vector<tl_object_ptr<td_api::stickerSetInfo>> result;
+  result.reserve(sticker_set_ids.size());
+  for (auto sticker_set_id : sticker_set_ids) {
+    auto sticker_set_info = get_sticker_set_info_object(sticker_set_id, covers_limit);
+    if (sticker_set_info->size_ != 0) {
+      result.push_back(std::move(sticker_set_info));
+    }
+  }
+
+  auto result_size = narrow_cast<int32>(result.size());
+  if (total_count < result_size) {
+    if (total_count != -1) {
+      LOG(ERROR) << "Have total_count = " << total_count << ", but there are " << result_size << " results";
+    }
+    total_count = result_size;
+  }
+  return make_tl_object<td_api::stickerSets>(total_count, std::move(result));
+}
+
+tl_object_ptr<td_api::stickerSetInfo> StickersManager::get_sticker_set_info_object(int64 sticker_set_id,
+                                                                                   size_t covers_limit) {
+  const StickerSet *sticker_set = get_sticker_set(sticker_set_id);
+  CHECK(sticker_set != nullptr);
+  CHECK(sticker_set->is_inited);
+
+  std::vector<tl_object_ptr<td_api::sticker>> stickers;
+  for (auto sticker_id : sticker_set->sticker_ids) {
+    stickers.push_back(get_sticker_object(sticker_id));
+    if (stickers.size() >= covers_limit) {
+      break;
+    }
+  }
+
+  return make_tl_object<td_api::stickerSetInfo>(
+      sticker_set->id, sticker_set->title, sticker_set->short_name,
+      sticker_set->is_installed && !sticker_set->is_archived, sticker_set->is_archived, sticker_set->is_official,
+      sticker_set->is_masks, sticker_set->is_viewed,
+      sticker_set->was_loaded ? narrow_cast<int32>(sticker_set->sticker_ids.size()) : sticker_set->sticker_count,
+      std::move(stickers));
+}
+
+tl_object_ptr<telegram_api::InputStickerSet> StickersManager::get_input_sticker_set(int64 sticker_set_id) const {
+  auto sticker_set = get_sticker_set(sticker_set_id);
+  if (sticker_set == nullptr) {
+    return nullptr;
+  }
+
+  return get_input_sticker_set(sticker_set);
+}
+
+FileId StickersManager::on_get_sticker(std::unique_ptr<Sticker> new_sticker, bool replace) {
+  auto file_id = new_sticker->file_id;
+  LOG(INFO) << "Receive sticker " << file_id;
+  auto &s = stickers_[file_id];
+  if (s == nullptr) {
+    s = std::move(new_sticker);
+  } else if (replace) {
+    CHECK(s->file_id == file_id);
+    if (s->dimensions != new_sticker->dimensions && new_sticker->dimensions.width != 0) {
+      LOG(DEBUG) << "Sticker " << file_id << " dimensions has changed";
+      s->dimensions = new_sticker->dimensions;
+      s->is_changed = true;
+    }
+    if (s->set_id != new_sticker->set_id && new_sticker->set_id != 0) {
+      LOG_IF(ERROR, s->set_id != 0) << "Sticker " << file_id << " set_id has changed";
+      s->set_id = new_sticker->set_id;
+      s->is_changed = true;
+    }
+    if (s->alt != new_sticker->alt && !new_sticker->alt.empty()) {
+      LOG(DEBUG) << "Sticker " << file_id << " emoji has changed";
+      s->alt = new_sticker->alt;
+      s->is_changed = true;
+    }
+    if (s->message_thumbnail != new_sticker->message_thumbnail && new_sticker->message_thumbnail.file_id.is_valid()) {
+      LOG_IF(INFO, s->message_thumbnail.file_id.is_valid())
+          << "Sticker " << file_id << " message thumbnail has changed from " << s->message_thumbnail << " to "
+          << new_sticker->message_thumbnail;
+      s->message_thumbnail = new_sticker->message_thumbnail;
+      s->is_changed = true;
+    }
+    if (s->sticker_thumbnail != new_sticker->sticker_thumbnail && new_sticker->sticker_thumbnail.file_id.is_valid()) {
+      LOG_IF(INFO, s->sticker_thumbnail.file_id.is_valid())
+          << "Sticker " << file_id << " thumbnail has changed from " << s->sticker_thumbnail << " to "
+          << new_sticker->sticker_thumbnail;
+      s->sticker_thumbnail = new_sticker->sticker_thumbnail;
+      s->is_changed = true;
+    }
+    if (s->is_mask != new_sticker->is_mask && new_sticker->is_mask) {
+      s->is_mask = new_sticker->is_mask;
+      s->is_changed = true;
+    }
+    if (s->point != new_sticker->point && new_sticker->point != -1) {
+      s->point = new_sticker->point;
+      s->x_shift = new_sticker->x_shift;
+      s->y_shift = new_sticker->y_shift;
+      s->scale = new_sticker->scale;
+      s->is_changed = true;
+    }
+  }
+
+  return file_id;
+}
+
+std::pair<int64, FileId> StickersManager::on_get_sticker_document(tl_object_ptr<telegram_api::Document> &&document_ptr,
+                                                                  bool from_message) {
+  int32 document_constructor_id = document_ptr->get_id();
+  if (document_constructor_id == telegram_api::documentEmpty::ID) {
+    LOG(ERROR) << "Empty sticker document received";
+    return {};
+  }
+  CHECK(document_constructor_id == telegram_api::document::ID);
+  auto document = move_tl_object_as<telegram_api::document>(document_ptr);
+
+  if (!DcId::is_valid(document->dc_id_)) {
+    LOG(ERROR) << "Wrong dc_id = " << document->dc_id_ << " in document " << to_string(document);
+    return {};
+  }
+
+  Dimensions dimensions;
+  tl_object_ptr<telegram_api::documentAttributeSticker> sticker;
+  for (auto &attribute : document->attributes_) {
+    switch (attribute->get_id()) {
+      case telegram_api::documentAttributeImageSize::ID: {
+        auto image_size = move_tl_object_as<telegram_api::documentAttributeImageSize>(attribute);
+        dimensions = get_dimensions(image_size->w_, image_size->h_);
+        break;
+      }
+      case telegram_api::documentAttributeSticker::ID:
+        sticker = move_tl_object_as<telegram_api::documentAttributeSticker>(attribute);
+        break;
+      default:
+        continue;
+    }
+  }
+  if (sticker == nullptr) {
+    LOG(ERROR) << "Have no attributeSticker in sticker " << to_string(document);
+    return {};
+  }
+
+  int64 document_id = document->id_;
+  FileId sticker_id = td_->file_manager_->register_remote(
+      FullRemoteFileLocation(FileType::Sticker, document_id, document->access_hash_, DcId::internal(document->dc_id_)),
+      FileLocationSource::FromServer, DialogId(), document->size_, 0, to_string(document_id) + ".webp");
+
+  PhotoSize thumbnail =
+      get_photo_size(td_->file_manager_.get(), FileType::Thumbnail, 0, 0, DialogId(), std::move(document->thumb_));
+
+  create_sticker(sticker_id, std::move(thumbnail), dimensions, from_message, std::move(sticker), nullptr);
+  return {document_id, sticker_id};
+}
+
+StickersManager::Sticker *StickersManager::get_sticker(FileId file_id) {
+  auto sticker = stickers_.find(file_id);
+  if (sticker == stickers_.end()) {
+    return nullptr;
+  }
+
+  CHECK(sticker->second->file_id == file_id);
+  return sticker->second.get();
+}
+
+const StickersManager::Sticker *StickersManager::get_sticker(FileId file_id) const {
+  auto sticker = stickers_.find(file_id);
+  if (sticker == stickers_.end()) {
+    return nullptr;
+  }
+
+  CHECK(sticker->second->file_id == file_id);
+  return sticker->second.get();
+}
+
+StickersManager::StickerSet *StickersManager::get_sticker_set(int64 sticker_set_id) {
+  auto sticker_set = sticker_sets_.find(sticker_set_id);
+  if (sticker_set == sticker_sets_.end()) {
+    return nullptr;
+  }
+
+  return sticker_set->second.get();
+}
+
+const StickersManager::StickerSet *StickersManager::get_sticker_set(int64 sticker_set_id) const {
+  auto sticker_set = sticker_sets_.find(sticker_set_id);
+  if (sticker_set == sticker_sets_.end()) {
+    return nullptr;
+  }
+
+  return sticker_set->second.get();
+}
+
+int64 StickersManager::add_sticker_set(tl_object_ptr<telegram_api::InputStickerSet> &&set_ptr) {
+  CHECK(set_ptr != nullptr);
+  switch (set_ptr->get_id()) {
+    case telegram_api::inputStickerSetEmpty::ID:
+      return 0;
+    case telegram_api::inputStickerSetID::ID: {
+      auto set = move_tl_object_as<telegram_api::inputStickerSetID>(set_ptr);
+      int64 set_id = set->id_;
+      add_sticker_set(set_id, set->access_hash_);
+      return set_id;
+    }
+    case telegram_api::inputStickerSetShortName::ID: {
+      auto set = move_tl_object_as<telegram_api::inputStickerSetShortName>(set_ptr);
+      LOG(ERROR) << "Receive sticker set by its short name";
+      return search_sticker_set(set->short_name_, Auto());
+    }
+    default:
+      UNREACHABLE();
+      return 0;
+  }
+}
+
+StickersManager::StickerSet *StickersManager::add_sticker_set(int64 sticker_set_id, int64 access_hash) {
+  auto &s = sticker_sets_[sticker_set_id];
+  if (s == nullptr) {
+    s = make_unique<StickerSet>();
+
+    s->id = sticker_set_id;
+    s->access_hash = access_hash;
+    s->is_changed = false;
+  } else {
+    CHECK(s->id == sticker_set_id);
+    if (s->access_hash != access_hash) {
+      s->access_hash = access_hash;
+      s->is_changed = true;
+    }
+  }
+  return s.get();
+}
+
+FileId StickersManager::get_sticker_thumbnail_file_id(FileId file_id) const {
+  auto sticker = get_sticker(file_id);
+  CHECK(sticker != nullptr);
+  return sticker->message_thumbnail.file_id;
+}
+
+void StickersManager::delete_sticker_thumbnail(FileId file_id) {
+  auto &sticker = stickers_[file_id];
+  CHECK(sticker != nullptr);
+  sticker->message_thumbnail = PhotoSize();
+}
+
+FileId StickersManager::dup_sticker(FileId new_id, FileId old_id) {
+  const Sticker *old_sticker = get_sticker(old_id);
+  CHECK(old_sticker != nullptr);
+  auto &new_sticker = stickers_[new_id];
+  CHECK(!new_sticker);
+  new_sticker = std::make_unique<Sticker>(*old_sticker);
+  new_sticker->file_id = new_id;
+  // there is no reason to dup sticker_thumb
+  new_sticker->message_thumbnail.file_id = td_->file_manager_->dup_file_id(new_sticker->message_thumbnail.file_id);
+  return new_id;
+}
+
+bool StickersManager::merge_stickers(FileId new_id, FileId old_id, bool can_delete_old) {
+  if (!old_id.is_valid()) {
+    LOG(ERROR) << "Old file id is invalid";
+    return true;
+  }
+
+  LOG(INFO) << "Merge stickers " << new_id << " and " << old_id;
+  const Sticker *old_ = get_sticker(old_id);
+  CHECK(old_ != nullptr);
+  if (old_id == new_id) {
+    return old_->is_changed;
+  }
+
+  auto new_it = stickers_.find(new_id);
+  if (new_it == stickers_.end()) {
+    auto &old = stickers_[old_id];
+    old->is_changed = true;
+    if (!can_delete_old) {
+      dup_sticker(new_id, old_id);
+    } else {
+      old->file_id = new_id;
+      stickers_.emplace(new_id, std::move(old));
+    }
+  } else {
+    Sticker *new_ = new_it->second.get();
+    CHECK(new_ != nullptr);
+
+    if (old_->alt != new_->alt || old_->set_id != new_->set_id ||
+        (old_->dimensions.width != 0 && old_->dimensions.height != 0 && old_->dimensions != new_->dimensions)) {
+      LOG(ERROR) << "Sticker has changed: alt = (" << old_->alt << ", " << new_->alt << "), set_id = (" << old_->set_id
+                 << ", " << new_->set_id << "), dimensions = (" << old_->dimensions << ", " << new_->dimensions << ")";
+    }
+
+    new_->is_changed = true;
+
+    if (old_->message_thumbnail != new_->message_thumbnail) {
+      //    LOG_STATUS(td_->file_manager_->merge(new_->message_thumbnail.file_id, old_->message_thumbnail.file_id));
+    }
+    if (old_->sticker_thumbnail != new_->sticker_thumbnail) {
+      //    LOG_STATUS(td_->file_manager_->merge(new_->sticker_thumbnail.file_id, old_->sticker_thumbnail.file_id));
+    }
+  }
+  LOG_STATUS(td_->file_manager_->merge(new_id, old_id));
+  if (can_delete_old) {
+    stickers_.erase(old_id);
+  }
+  return true;
+}
+
+tl_object_ptr<telegram_api::InputStickerSet> StickersManager::get_input_sticker_set(const StickerSet *set) {
+  CHECK(set != nullptr);
+  return make_tl_object<telegram_api::inputStickerSetID>(set->id, set->access_hash);
+}
+
+void StickersManager::reload_installed_sticker_sets(bool is_masks, bool force) {
+  auto &next_load_time = next_installed_sticker_sets_load_time_[is_masks];
+  if (!td_->auth_manager_->is_bot() && next_load_time >= 0 && (next_load_time < Time::now() || force)) {
+    LOG_IF(INFO, force) << "Reload sticker sets";
+    next_load_time = -1;
+    td_->create_handler<GetAllStickersQuery>()->send(is_masks, installed_sticker_sets_hash_[is_masks]);
+  }
+}
+
+void StickersManager::reload_featured_sticker_sets(bool force) {
+  if (!td_->auth_manager_->is_bot() && next_featured_sticker_sets_load_time_ >= 0 &&
+      (next_featured_sticker_sets_load_time_ < Time::now() || force)) {
+    LOG_IF(INFO, force) << "Reload featured sticker sets";
+    next_featured_sticker_sets_load_time_ = -1;
+    td_->create_handler<GetFeaturedStickerSetsQuery>()->send(featured_sticker_sets_hash_);
+  }
+}
+
+int64 StickersManager::on_get_input_sticker_set(FileId sticker_file_id,
+                                                tl_object_ptr<telegram_api::InputStickerSet> &&set_ptr,
+                                                MultiPromiseActor *load_data_multipromise_ptr) {
+  if (set_ptr == nullptr) {
+    return 0;
+  }
+  switch (set_ptr->get_id()) {
+    case telegram_api::inputStickerSetEmpty::ID:
+      return 0;
+    case telegram_api::inputStickerSetID::ID: {
+      auto set = move_tl_object_as<telegram_api::inputStickerSetID>(set_ptr);
+      int64 set_id = set->id_;
+      add_sticker_set(set_id, set->access_hash_);
+      return set_id;
+    }
+    case telegram_api::inputStickerSetShortName::ID: {
+      auto set = move_tl_object_as<telegram_api::inputStickerSetShortName>(set_ptr);
+      if (load_data_multipromise_ptr == nullptr) {
+        LOG(ERROR) << "Receive sticker set by its short name";
+        return search_sticker_set(set->short_name_, Auto());
+      }
+      auto set_id = search_sticker_set(set->short_name_, load_data_multipromise_ptr->get_promise());
+      if (set_id == 0) {
+        load_data_multipromise_ptr->add_promise(
+            PromiseCreator::lambda([td = td_, sticker_file_id, short_name = set->short_name_](Result<Unit> result) {
+              if (result.is_ok()) {
+                // just in case
+                td->stickers_manager_->on_resolve_sticker_set_short_name(sticker_file_id, short_name);
+              }
+            }));
+      }
+      return set_id;
+    }
+    default:
+      UNREACHABLE();
+      return 0;
+  }
+}
+
+void StickersManager::on_resolve_sticker_set_short_name(FileId sticker_file_id, const string &short_name) {
+  LOG(INFO) << "Resolve sticker " << sticker_file_id << " set to " << short_name;
+  int64 set_id = search_sticker_set(short_name, Auto());
+  if (set_id != 0) {
+    auto &s = stickers_[sticker_file_id];
+    if (s == nullptr) {
+      LOG(ERROR) << "Can't find sticker " << sticker_file_id;
+    }
+    CHECK(s->file_id == sticker_file_id);
+    if (s->set_id != set_id) {
+      s->set_id = set_id;
+      s->is_changed = true;
+    }
+  }
+}
+
+void StickersManager::create_sticker(FileId file_id, PhotoSize thumbnail, Dimensions dimensions, bool from_message,
+                                     tl_object_ptr<telegram_api::documentAttributeSticker> sticker,
+                                     MultiPromiseActor *load_data_multipromise_ptr) {
+  auto s = make_unique<Sticker>();
+  s->file_id = file_id;
+  s->dimensions = dimensions;
+  if (from_message) {
+    s->message_thumbnail = std::move(thumbnail);
+  } else {
+    s->sticker_thumbnail = std::move(thumbnail);
+  }
+  if (sticker != nullptr) {
+    s->set_id = on_get_input_sticker_set(file_id, std::move(sticker->stickerset_), load_data_multipromise_ptr);
+    s->alt = std::move(sticker->alt_);
+
+    s->is_mask = (sticker->flags_ & telegram_api::documentAttributeSticker::MASK_MASK) != 0;
+    if ((sticker->flags_ & telegram_api::documentAttributeSticker::MASK_COORDS_MASK) != 0) {
+      CHECK(sticker->mask_coords_ != nullptr);
+      int32 point = sticker->mask_coords_->n_;
+      if (0 <= point && point <= 3) {
+        s->point = sticker->mask_coords_->n_;
+        s->x_shift = sticker->mask_coords_->x_;
+        s->y_shift = sticker->mask_coords_->y_;
+        s->scale = sticker->mask_coords_->zoom_;
+      }
+    }
+  }
+  on_get_sticker(std::move(s), sticker != nullptr);
+}
+
+bool StickersManager::has_input_media(FileId sticker_file_id, bool is_secret) const {
+  const Sticker *sticker = get_sticker(sticker_file_id);
+  CHECK(sticker != nullptr);
+  auto file_view = td_->file_manager_->get_file_view(sticker_file_id);
+  if (is_secret) {
+    if (file_view.is_encrypted()) {
+      if (file_view.has_remote_location() && !sticker->message_thumbnail.file_id.is_valid()) {
+        return true;
+      }
+    } else {
+      if (sticker->set_id != 0) {
+        // stickers within a set can be sent by id and access_hash
+        return true;
+      }
+    }
+  } else {
+    if (file_view.is_encrypted()) {
+      return false;
+    }
+    if (file_view.has_remote_location() || file_view.has_url()) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+SecretInputMedia StickersManager::get_secret_input_media(FileId sticker_file_id,
+                                                         tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                                         BufferSlice thumbnail) const {
+  const Sticker *sticker = get_sticker(sticker_file_id);
+  CHECK(sticker != nullptr);
+  auto file_view = td_->file_manager_->get_file_view(sticker_file_id);
+  if (file_view.is_encrypted()) {
+    if (file_view.has_remote_location()) {
+      input_file = file_view.remote_location().as_input_encrypted_file();
+    }
+    if (!input_file) {
+      return {};
+    }
+    if (sticker->message_thumbnail.file_id.is_valid() && thumbnail.empty()) {
+      return {};
+    }
+  } else {
+    if (sticker->set_id == 0) {
+      // stickers without set can't be sent by id and access_hash
+      return {};
+    }
+  }
+
+  vector<tl_object_ptr<secret_api::DocumentAttribute>> attributes;
+  tl_object_ptr<secret_api::InputStickerSet> input_sticker_set = make_tl_object<secret_api::inputStickerSetEmpty>();
+  if (sticker->set_id) {
+    const StickerSet *sticker_set = get_sticker_set(sticker->set_id);
+    CHECK(sticker_set != nullptr);
+    if (sticker_set->is_inited) {
+      input_sticker_set = make_tl_object<secret_api::inputStickerSetShortName>(sticker_set->short_name);
+    } else {
+      // TODO load sticker set
+    }
+  }
+  attributes.push_back(
+      make_tl_object<secret_api::documentAttributeSticker>(sticker->alt, std::move(input_sticker_set)));
+
+  if (sticker->dimensions.width != 0 && sticker->dimensions.height != 0) {
+    attributes.push_back(
+        make_tl_object<secret_api::documentAttributeImageSize>(sticker->dimensions.width, sticker->dimensions.height));
+  }
+
+  if (file_view.is_encrypted()) {
+    auto &encryption_key = file_view.encryption_key();
+    return SecretInputMedia{std::move(input_file),
+                            make_tl_object<secret_api::decryptedMessageMediaDocument>(
+                                std::move(thumbnail), sticker->message_thumbnail.dimensions.width,
+                                sticker->message_thumbnail.dimensions.height, "image/webp",
+                                narrow_cast<int32>(file_view.size()), BufferSlice(encryption_key.key_slice()),
+                                BufferSlice(encryption_key.iv_slice()), std::move(attributes), "")};
+  } else {
+    auto &remote_location = file_view.remote_location();
+    CHECK(!remote_location.is_web());  // web stickers shouldn't have set_id
+    return SecretInputMedia{nullptr,
+                            make_tl_object<secret_api::decryptedMessageMediaExternalDocument>(
+                                remote_location.get_id(), remote_location.get_access_hash(), 0 /*date*/, "image/webp",
+                                narrow_cast<int32>(file_view.size()), make_tl_object<secret_api::photoSizeEmpty>(),
+                                remote_location.get_dc_id().get_raw_id(), std::move(attributes))};
+  }
+}
+
+tl_object_ptr<telegram_api::InputMedia> StickersManager::get_input_media(
+    FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file,
+    tl_object_ptr<telegram_api::InputFile> input_thumbnail) const {
+  auto file_view = td_->file_manager_->get_file_view(file_id);
+  if (file_view.is_encrypted()) {
+    return nullptr;
+  }
+  if (file_view.has_remote_location() && !file_view.remote_location().is_web()) {
+    return make_tl_object<telegram_api::inputMediaDocument>(0, file_view.remote_location().as_input_document(), 0);
+  }
+  if (file_view.has_url()) {
+    return make_tl_object<telegram_api::inputMediaDocumentExternal>(0, file_view.url(), 0);
+  }
+  CHECK(!file_view.has_remote_location());
+
+  if (input_file != nullptr) {
+    const Sticker *s = get_sticker(file_id);
+    CHECK(s != nullptr);
+
+    vector<tl_object_ptr<telegram_api::DocumentAttribute>> attributes;
+    if (s->dimensions.width != 0 && s->dimensions.height != 0) {
+      attributes.push_back(
+          make_tl_object<telegram_api::documentAttributeImageSize>(s->dimensions.width, s->dimensions.height));
+    }
+    attributes.push_back(make_tl_object<telegram_api::documentAttributeSticker>(
+        0, false /*ignored*/, s->alt, make_tl_object<telegram_api::inputStickerSetEmpty>(), nullptr));
+
+    int32 flags = 0;
+    if (input_thumbnail != nullptr) {
+      flags |= telegram_api::inputMediaUploadedDocument::THUMB_MASK;
+    }
+    return make_tl_object<telegram_api::inputMediaUploadedDocument>(
+        flags, false /*ignored*/, std::move(input_file), std::move(input_thumbnail), "image/webp",
+        std::move(attributes), vector<tl_object_ptr<telegram_api::InputDocument>>(), 0);
+  }
+
+  return nullptr;
+}
+
+int64 StickersManager::on_get_sticker_set(tl_object_ptr<telegram_api::stickerSet> &&set, bool is_changed) {
+  int64 set_id = set->id_;
+  StickerSet *s = add_sticker_set(set_id, set->access_hash_);
+
+  bool is_installed = (set->flags_ & telegram_api::stickerSet::INSTALLED_DATE_MASK) != 0;
+  bool is_archived = (set->flags_ & telegram_api::stickerSet::ARCHIVED_MASK) != 0;
+  bool is_official = (set->flags_ & telegram_api::stickerSet::OFFICIAL_MASK) != 0;
+  bool is_masks = (set->flags_ & telegram_api::stickerSet::MASKS_MASK) != 0;
+
+  if (!s->is_inited) {
+    s->is_inited = true;
+    s->title = std::move(set->title_);
+    s->short_name = std::move(set->short_name_);
+    s->sticker_count = set->count_;
+    s->hash = set->hash_;
+    s->is_official = is_official;
+    s->is_masks = is_masks;
+    s->is_changed = true;
+  } else {
+    CHECK(s->id == set_id);
+    if (s->access_hash != set->access_hash_) {
+      LOG(INFO) << "Sticker set " << set_id << " access hash has changed";
+      s->access_hash = set->access_hash_;
+      s->is_changed = true;
+    }
+    if (s->title != set->title_) {
+      LOG(INFO) << "Sticker set " << set_id << " title has changed";
+      s->title = std::move(set->title_);
+      s->is_changed = true;
+
+      if (installed_sticker_sets_hints_[s->is_masks].has_key(set_id)) {
+        installed_sticker_sets_hints_[s->is_masks].add(set_id, s->title + " " + s->short_name);
+      }
+    }
+    if (s->short_name != set->short_name_) {
+      LOG(ERROR) << "Sticker set " << set_id << " short name has changed from \"" << s->short_name << "\" to \""
+                 << set->short_name_ << "\"";
+      short_name_to_sticker_set_id_.erase(clean_username(s->short_name));
+      s->short_name = std::move(set->short_name_);
+      s->is_changed = true;
+
+      if (installed_sticker_sets_hints_[s->is_masks].has_key(set_id)) {
+        installed_sticker_sets_hints_[s->is_masks].add(set_id, s->title + " " + s->short_name);
+      }
+    }
+
+    if (s->sticker_count != set->count_ || s->hash != set->hash_) {
+      s->is_loaded = false;
+
+      s->sticker_count = set->count_;
+      s->hash = set->hash_;
+      s->is_changed = true;
+    }
+
+    if (s->is_official != is_official) {
+      s->is_official = is_official;
+      s->is_changed = true;
+    }
+    LOG_IF(ERROR, s->is_masks != is_masks) << "Type of the sticker set " << set_id << " has changed";
+  }
+  short_name_to_sticker_set_id_.emplace(clean_username(s->short_name), set_id);
+
+  on_update_sticker_set(s, is_installed, is_archived, is_changed);
+
+  return set_id;
+}
+
+int64 StickersManager::on_get_sticker_set_covered(tl_object_ptr<telegram_api::StickerSetCovered> &&set_ptr,
+                                                  bool is_changed) {
+  int64 set_id = 0;
+  switch (set_ptr->get_id()) {
+    case telegram_api::stickerSetCovered::ID: {
+      auto covered_set = move_tl_object_as<telegram_api::stickerSetCovered>(set_ptr);
+      set_id = on_get_sticker_set(std::move(covered_set->set_), is_changed);
+      if (set_id == 0) {
+        break;
+      }
+
+      auto sticker_set = get_sticker_set(set_id);
+      CHECK(sticker_set != nullptr);
+      CHECK(sticker_set->is_inited);
+      if (sticker_set->was_loaded) {
+        break;
+      }
+      if (sticker_set->sticker_count == 0) {
+        break;
+      }
+
+      auto &sticker_ids = sticker_set->sticker_ids;
+
+      auto sticker_id = on_get_sticker_document(std::move(covered_set->cover_), true).second;
+      if (sticker_id.is_valid() && std::find(sticker_ids.begin(), sticker_ids.end(), sticker_id) == sticker_ids.end()) {
+        sticker_ids.push_back(sticker_id);
+        sticker_set->is_changed = true;
+      }
+
+      break;
+    }
+    case telegram_api::stickerSetMultiCovered::ID: {
+      auto multicovered_set = move_tl_object_as<telegram_api::stickerSetMultiCovered>(set_ptr);
+      set_id = on_get_sticker_set(std::move(multicovered_set->set_), is_changed);
+      if (set_id == 0) {
+        break;
+      }
+
+      auto sticker_set = get_sticker_set(set_id);
+      CHECK(sticker_set != nullptr);
+      CHECK(sticker_set->is_inited);
+      if (sticker_set->was_loaded) {
+        break;
+      }
+      auto &sticker_ids = sticker_set->sticker_ids;
+
+      for (auto &cover : multicovered_set->covers_) {
+        auto sticker_id = on_get_sticker_document(std::move(cover), true).second;
+        if (sticker_id.is_valid() &&
+            std::find(sticker_ids.begin(), sticker_ids.end(), sticker_id) == sticker_ids.end()) {
+          sticker_ids.push_back(sticker_id);
+          sticker_set->is_changed = true;
+        }
+      }
+
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+  return set_id;
+}
+
+void StickersManager::on_get_messages_sticker_set(int64 sticker_set_id,
+                                                  tl_object_ptr<telegram_api::messages_stickerSet> &&set,
+                                                  bool is_changed) {
+  LOG(INFO) << "Receive sticker set " << to_string(set);
+
+  auto set_id = on_get_sticker_set(std::move(set->set_), is_changed);
+  if (set_id == 0) {
+    return;
+  }
+  if (sticker_set_id != 0 && sticker_set_id != set_id) {
+    LOG(ERROR) << "Expected sticker set " << sticker_set_id << ", but receive sticker set " << set_id;
+    on_load_sticker_set_fail(sticker_set_id, Status::Error(500, "Internal server error"));
+    return;
+  }
+
+  auto s = get_sticker_set(set_id);
+  CHECK(s != nullptr);
+  CHECK(s->is_inited);
+
+  s->expires_at = G()->unix_time() + (td_->auth_manager_->is_bot() ? Random::fast(10 * 60, 15 * 60)
+                                                                   : Random::fast(20 * 60 * 60, 28 * 60 * 60));
+
+  if (s->is_loaded) {
+    update_sticker_set(s);
+    send_update_installed_sticker_sets();
+    return;
+  }
+  s->was_loaded = true;
+  s->is_loaded = true;
+  s->is_changed = true;
+
+  vector<tl_object_ptr<telegram_api::stickerPack>> packs = std::move(set->packs_);
+  vector<tl_object_ptr<telegram_api::Document>> documents = std::move(set->documents_);
+
+  std::unordered_map<int64, FileId> document_id_to_sticker_id;
+
+  s->sticker_ids.clear();
+  for (auto &document_ptr : documents) {
+    auto sticker_id = on_get_sticker_document(std::move(document_ptr), false);
+    if (!sticker_id.second.is_valid()) {
+      continue;
+    }
+
+    s->sticker_ids.push_back(sticker_id.second);
+    document_id_to_sticker_id.insert(sticker_id);
+  }
+  if (static_cast<int>(s->sticker_ids.size()) != s->sticker_count) {
+    LOG(ERROR) << "Wrong sticker set size specified";
+    s->sticker_count = static_cast<int>(s->sticker_ids.size());
+  }
+
+  s->emoji_stickers_map_.clear();
+  s->sticker_emojis_map_.clear();
+  for (auto &pack : packs) {
+    vector<FileId> stickers;
+    stickers.reserve(pack->documents_.size());
+    for (int64 document_id : pack->documents_) {
+      auto it = document_id_to_sticker_id.find(document_id);
+      if (it == document_id_to_sticker_id.end()) {
+        LOG(ERROR) << "Can't find document with id " << document_id;
+        continue;
+      }
+
+      stickers.push_back(it->second);
+      s->sticker_emojis_map_[it->second].push_back(pack->emoticon_);
+    }
+    s->emoji_stickers_map_.emplace(remove_emoji_modifiers(pack->emoticon_), std::move(stickers));
+  }
+
+  update_sticker_set(s);
+  update_load_requests(s, true, Status::OK());
+  send_update_installed_sticker_sets();
+}
+
+void StickersManager::on_load_sticker_set_fail(int64 sticker_set_id, const Status &error) {
+  if (sticker_set_id == 0) {
+    return;
+  }
+  update_load_requests(get_sticker_set(sticker_set_id), true, error);
+}
+
+void StickersManager::update_load_requests(StickerSet *sticker_set, bool with_stickers, const Status &status) {
+  if (sticker_set == nullptr) {
+    return;
+  }
+  if (with_stickers) {
+    for (auto load_request_id : sticker_set->load_requests) {
+      update_load_request(load_request_id, status);
+    }
+
+    sticker_set->load_requests.clear();
+  }
+  for (auto load_request_id : sticker_set->load_without_stickers_requests) {
+    update_load_request(load_request_id, status);
+  }
+
+  sticker_set->load_without_stickers_requests.clear();
+}
+
+void StickersManager::update_load_request(uint32 load_request_id, const Status &status) {
+  auto it = sticker_set_load_requests_.find(load_request_id);
+  CHECK(it != sticker_set_load_requests_.end());
+  CHECK(it->second.left_queries > 0);
+  if (status.is_error() && it->second.error.is_ok()) {
+    it->second.error = status.clone();
+  }
+  if (--it->second.left_queries == 0) {
+    if (it->second.error.is_ok()) {
+      it->second.promise.set_value(Unit());
+    } else {
+      it->second.promise.set_error(std::move(it->second.error));
+    }
+    sticker_set_load_requests_.erase(it);
+  }
+}
+
+void StickersManager::on_get_installed_sticker_sets(bool is_masks,
+                                                    tl_object_ptr<telegram_api::messages_AllStickers> &&stickers_ptr) {
+  next_installed_sticker_sets_load_time_[is_masks] = Time::now_cached() + Random::fast(30 * 60, 50 * 60);
+
+  CHECK(stickers_ptr != nullptr);
+  int32 constructor_id = stickers_ptr->get_id();
+  if (constructor_id == telegram_api::messages_allStickersNotModified::ID) {
+    LOG(INFO) << (is_masks ? "Masks" : "Stickers") << " are not modified";
+    return;
+  }
+  CHECK(constructor_id == telegram_api::messages_allStickers::ID);
+  auto stickers = move_tl_object_as<telegram_api::messages_allStickers>(stickers_ptr);
+
+  std::unordered_set<int64> uninstalled_sticker_sets(installed_sticker_set_ids_[is_masks].begin(),
+                                                     installed_sticker_set_ids_[is_masks].end());
+
+  vector<int64> sets_to_load;
+  vector<int64> installed_sticker_set_ids;
+  vector<int32> hashes;
+  vector<int64> sticker_set_ids;
+  std::reverse(stickers->sets_.begin(), stickers->sets_.end());  // apply installed sticker sets in reverse order
+  for (auto &set : stickers->sets_) {
+    hashes.push_back(set->hash_);
+    sticker_set_ids.push_back(set->id_);
+    int64 set_id = on_get_sticker_set(std::move(set), false);
+    if (set_id == 0) {
+      continue;
+    }
+
+    auto sticker_set = get_sticker_set(set_id);
+    CHECK(sticker_set != nullptr);
+    LOG_IF(ERROR, !sticker_set->is_installed) << "Receive non-installed sticker set in getAllStickers";
+    LOG_IF(ERROR, sticker_set->is_archived) << "Receive archived sticker set in getAllStickers";
+    LOG_IF(ERROR, sticker_set->is_masks != is_masks) << "Receive sticker set of a wrong type in getAllStickers";
+    CHECK(sticker_set->is_inited);
+
+    if (sticker_set->is_installed && !sticker_set->is_archived && sticker_set->is_masks == is_masks) {
+      installed_sticker_set_ids.push_back(set_id);
+      uninstalled_sticker_sets.erase(set_id);
+    }
+    update_sticker_set(sticker_set);
+
+    if (!sticker_set->is_archived && !sticker_set->is_loaded) {
+      sets_to_load.push_back(set_id);
+    }
+  }
+  std::reverse(hashes.begin(), hashes.end());
+  std::reverse(installed_sticker_set_ids.begin(), installed_sticker_set_ids.end());
+  std::reverse(sticker_set_ids.begin(), sticker_set_ids.end());
+
+  if (!sets_to_load.empty()) {
+    load_sticker_sets(std::move(sets_to_load), Auto());
+  }
+
+  for (auto set_id : uninstalled_sticker_sets) {
+    auto sticker_set = get_sticker_set(set_id);
+    CHECK(sticker_set != nullptr);
+    CHECK(sticker_set->is_installed && !sticker_set->is_archived);
+    on_update_sticker_set(sticker_set, false, false, true);
+    update_sticker_set(sticker_set);
+  }
+
+  on_load_installed_sticker_sets_finished(is_masks, std::move(installed_sticker_set_ids));
+
+  if (installed_sticker_sets_hash_[is_masks] != stickers->hash_) {
+    LOG(ERROR) << "Sticker sets hash mismatch: server hash list = " << format::as_array(hashes)
+               << ", client hash list = "
+               << format::as_array(
+                      transform(installed_sticker_set_ids_[is_masks],
+                                [this](int64 sticker_set_id) { return get_sticker_set(sticker_set_id)->hash; }))
+               << ", server sticker set list = " << format::as_array(sticker_set_ids)
+               << ", client sticker set list = " << format::as_array(installed_sticker_set_ids_[is_masks])
+               << ", server hash = " << stickers->hash_ << ", client hash = " << installed_sticker_sets_hash_[is_masks];
+  }
+}
+
+void StickersManager::on_get_installed_sticker_sets_failed(bool is_masks, Status error) {
+  CHECK(error.is_error());
+  next_installed_sticker_sets_load_time_[is_masks] = Time::now_cached() + Random::fast(5, 10);
+  auto promises = std::move(load_installed_sticker_sets_queries_[is_masks]);
+  load_installed_sticker_sets_queries_[is_masks].clear();
+  for (auto &promise : promises) {
+    promise.set_error(error.clone());
+  }
+}
+
+vector<FileId> StickersManager::get_stickers(string emoji, int32 limit, bool force, Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    promise.set_error(Status::Error(7, "Method is not available for bots"));
+    return {};
+  }
+  if (limit <= 0) {
+    promise.set_error(Status::Error(3, "Parameter limit must be positive"));
+    return {};
+  }
+  if (!are_installed_sticker_sets_loaded_[0]) {
+    load_installed_sticker_sets(false, std::move(promise));
+    return {};
+  }
+
+  emoji = remove_emoji_modifiers(emoji);
+  if (!emoji.empty()) {
+    if (!are_recent_stickers_loaded_[0]) {
+      load_recent_stickers(false, std::move(promise));
+      return {};
+    }
+    if (!are_favorite_stickers_loaded_) {
+      load_favorite_stickers(std::move(promise));
+      return {};
+    }
+    /*
+    if (!are_featured_sticker_sets_loaded_) {
+      load_featured_sticker_sets(std::move(promise));
+      return {};
+    }
+    */
+  }
+
+  vector<int64> sets_to_load;
+  bool need_load = false;
+  for (const auto &sticker_set_id : installed_sticker_set_ids_[0]) {
+    const StickerSet *sticker_set = get_sticker_set(sticker_set_id);
+    CHECK(sticker_set != nullptr);
+    CHECK(sticker_set->is_inited);
+    CHECK(!sticker_set->is_archived);
+    if (!sticker_set->is_loaded) {
+      sets_to_load.push_back(sticker_set_id);
+      if (!sticker_set->was_loaded) {
+        need_load = true;
+      }
+    }
+  }
+
+  vector<FileId> prepend_sticker_ids;
+  if (!emoji.empty()) {
+    prepend_sticker_ids.reserve(favorite_sticker_ids_.size() + recent_sticker_ids_[0].size());
+    append(prepend_sticker_ids, recent_sticker_ids_[0]);
+    for (auto sticker_id : favorite_sticker_ids_) {
+      if (std::find(prepend_sticker_ids.begin(), prepend_sticker_ids.end(), sticker_id) == prepend_sticker_ids.end()) {
+        prepend_sticker_ids.push_back(sticker_id);
+      }
+    }
+
+    for (const auto &sticker_id : prepend_sticker_ids) {
+      const Sticker *s = get_sticker(sticker_id);
+      if (s->set_id != 0 && std::find(sets_to_load.begin(), sets_to_load.end(), s->set_id) == sets_to_load.end()) {
+        const StickerSet *sticker_set = get_sticker_set(s->set_id);
+        if (sticker_set == nullptr || !sticker_set->is_loaded) {
+          sets_to_load.push_back(s->set_id);
+          if (sticker_set == nullptr || !sticker_set->was_loaded) {
+            need_load = true;
+          }
+        }
+      }
+    }
+  }
+
+  if (!sets_to_load.empty()) {
+    if (need_load && !force) {
+      load_sticker_sets(std::move(sets_to_load),
+                        PromiseCreator::lambda([promise = std::move(promise)](Result<Unit> result) mutable {
+                          if (result.is_error() && result.error().message() != "STICKERSET_INVALID") {
+                            LOG(ERROR) << "Failed to load sticker sets: " << result.error();
+                          }
+                          promise.set_value(Unit());
+                        }));
+      return {};
+    } else {
+      load_sticker_sets(std::move(sets_to_load), Auto());
+    }
+  }
+
+  vector<FileId> result;
+  auto limit_size_t = static_cast<size_t>(limit);
+  if (emoji.empty()) {
+    for (const auto &sticker_set_id : installed_sticker_set_ids_[0]) {
+      const StickerSet *sticker_set = get_sticker_set(sticker_set_id);
+      if (sticker_set == nullptr || !sticker_set->was_loaded) {
+        continue;
+      }
+
+      append(result, sticker_set->sticker_ids);
+      if (result.size() > limit_size_t) {
+        result.resize(limit_size_t);
+        break;
+      }
+    }
+  } else {
+    vector<int64> examined_sticker_set_ids;  // = featured_sticker_set_ids_;
+    for (const auto &sticker_set_id : installed_sticker_set_ids_[0]) {
+      if (std::find(examined_sticker_set_ids.begin(), examined_sticker_set_ids.end(), sticker_set_id) ==
+          examined_sticker_set_ids.end()) {
+        examined_sticker_set_ids.push_back(sticker_set_id);
+      }
+    }
+    for (const auto &sticker_set_id : examined_sticker_set_ids) {
+      const StickerSet *sticker_set = get_sticker_set(sticker_set_id);
+      if (sticker_set == nullptr || !sticker_set->was_loaded) {
+        continue;
+      }
+
+      auto it = sticker_set->emoji_stickers_map_.find(emoji);
+      if (it != sticker_set->emoji_stickers_map_.end()) {
+        append(result, it->second);
+      }
+    }
+
+    vector<FileId> sorted;
+    sorted.reserve(min(limit_size_t, result.size()));
+    auto recent_stickers_size = recent_sticker_ids_[0].size();
+    const size_t MAX_RECENT_STICKERS = 5;
+    for (size_t i = 0; i < prepend_sticker_ids.size(); i++) {
+      if (sorted.size() == MAX_RECENT_STICKERS && i < recent_stickers_size) {
+        continue;
+      }
+
+      auto sticker_id = prepend_sticker_ids[i];
+      bool is_good = false;
+      auto it = std::find(result.begin(), result.end(), sticker_id);
+      if (it != result.end()) {
+        *it = FileId();
+        is_good = true;
+      } else {
+        const Sticker *s = get_sticker(sticker_id);
+        if (remove_emoji_modifiers(s->alt) == emoji) {
+          is_good = true;
+        } else if (s->set_id != 0) {
+          const StickerSet *sticker_set = get_sticker_set(s->set_id);
+          if (sticker_set != nullptr && sticker_set->was_loaded) {
+            auto map_it = sticker_set->emoji_stickers_map_.find(emoji);
+            if (map_it != sticker_set->emoji_stickers_map_.end()) {
+              if (std::find(map_it->second.begin(), map_it->second.end(), sticker_id) != map_it->second.end()) {
+                is_good = true;
+              }
+            }
+          }
+        }
+      }
+
+      if (is_good) {
+        sorted.push_back(sticker_id);
+        if (sorted.size() == limit_size_t) {
+          break;
+        }
+      }
+    }
+    if (sorted.size() != limit_size_t) {
+      for (const auto &sticker_id : result) {
+        if (sticker_id.is_valid()) {
+          sorted.push_back(sticker_id);
+          if (sorted.size() == limit_size_t) {
+            break;
+          }
+        }
+      }
+    }
+
+    result = std::move(sorted);
+  }
+
+  promise.set_value(Unit());
+  return result;
+}
+
+vector<FileId> StickersManager::search_stickers(string emoji, int32 limit, Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    promise.set_error(Status::Error(7, "Method is not available for bots"));
+    return {};
+  }
+  if (limit <= 0) {
+    promise.set_error(Status::Error(3, "Parameter limit must be positive"));
+    return {};
+  }
+  if (limit > MAX_FOUND_STICKERS) {
+    limit = MAX_FOUND_STICKERS;
+  }
+  if (emoji.empty()) {
+    promise.set_error(Status::Error(3, "Emoji must be non-empty"));
+    return {};
+  }
+
+  emoji = remove_emoji_modifiers(emoji);
+  if (emoji.empty()) {
+    promise.set_value(Unit());
+    return {};
+  }
+
+  auto it = found_stickers_.find(emoji);
+  if (it != found_stickers_.end()) {
+    promise.set_value(Unit());
+    auto result_size = min(static_cast<size_t>(limit), it->second.size());
+    return vector<FileId>(it->second.begin(), it->second.begin() + result_size);
+  }
+
+  auto &promises = search_stickers_queries_[emoji];
+  promises.push_back(std::move(promise));
+  if (promises.size() == 1u) {
+    td_->create_handler<SearchStickersQuery>()->send(std::move(emoji));
+  }
+
+  return {};
+}
+
+void StickersManager::on_find_stickers_success(const string &emoji,
+                                               tl_object_ptr<telegram_api::messages_Stickers> &&stickers) {
+  CHECK(stickers != nullptr);
+  switch (stickers->get_id()) {
+    case telegram_api::messages_stickersNotModified::ID:
+      return on_find_stickers_fail(emoji, Status::Error(500, "Receive messages.stickerNotModified"));
+    case telegram_api::messages_stickers::ID: {
+      auto found_stickers = move_tl_object_as<telegram_api::messages_stickers>(stickers);
+      vector<FileId> &sticker_ids = found_stickers_[emoji];
+      CHECK(sticker_ids.empty());
+
+      for (auto &sticker : found_stickers->stickers_) {
+        FileId sticker_id = on_get_sticker_document(std::move(sticker), false).second;
+        if (sticker_id.is_valid()) {
+          sticker_ids.push_back(sticker_id);
+        }
+      }
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+
+  auto it = search_stickers_queries_.find(emoji);
+  CHECK(it != search_stickers_queries_.end());
+  CHECK(!it->second.empty());
+  auto promises = std::move(it->second);
+  search_stickers_queries_.erase(it);
+
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+void StickersManager::on_find_stickers_fail(const string &emoji, Status &&error) {
+  CHECK(found_stickers_.count(emoji) == 0);
+
+  auto it = search_stickers_queries_.find(emoji);
+  CHECK(it != search_stickers_queries_.end());
+  CHECK(!it->second.empty());
+  auto promises = std::move(it->second);
+  search_stickers_queries_.erase(it);
+
+  for (auto &promise : promises) {
+    promise.set_error(error.clone());
+  }
+}
+
+vector<int64> StickersManager::get_installed_sticker_sets(bool is_masks, Promise<Unit> &&promise) {
+  if (!are_installed_sticker_sets_loaded_[is_masks]) {
+    load_installed_sticker_sets(is_masks, std::move(promise));
+    return {};
+  }
+  reload_installed_sticker_sets(is_masks, false);
+
+  promise.set_value(Unit());
+  return installed_sticker_set_ids_[is_masks];
+}
+
+bool StickersManager::update_sticker_set_cache(const StickerSet *sticker_set, Promise<Unit> &promise) {
+  CHECK(sticker_set != nullptr);
+  auto set_id = sticker_set->id;
+  if (!sticker_set->is_loaded) {
+    if (!sticker_set->was_loaded || td_->auth_manager_->is_bot()) {
+      load_sticker_sets({set_id}, std::move(promise));
+      return true;
+    } else {
+      load_sticker_sets({set_id}, Auto());
+    }
+  } else if (sticker_set->is_installed) {
+    reload_installed_sticker_sets(sticker_set->is_masks, false);
+  } else {
+    if (G()->unix_time() >= sticker_set->expires_at) {
+      if (td_->auth_manager_->is_bot()) {
+        reload_sticker_set(set_id, get_input_sticker_set(sticker_set), std::move(promise));
+        return true;
+      } else {
+        reload_sticker_set(set_id, get_input_sticker_set(sticker_set), Auto());
+      }
+    }
+  }
+
+  return false;
+}
+
+int64 StickersManager::get_sticker_set(int64 set_id, Promise<Unit> &&promise) {
+  const StickerSet *sticker_set = get_sticker_set(set_id);
+  if (sticker_set == nullptr) {
+    if (set_id == GREAT_MINDS_SET_ID) {
+      reload_sticker_set(set_id, make_tl_object<telegram_api::inputStickerSetID>(set_id, 0), std::move(promise));
+      return 0;
+    }
+
+    promise.set_error(Status::Error(400, "Sticker set not found"));
+    return 0;
+  }
+
+  if (update_sticker_set_cache(sticker_set, promise)) {
+    return 0;
+  }
+
+  promise.set_value(Unit());
+  return set_id;
+}
+
+int64 StickersManager::search_sticker_set(const string &short_name_to_search, Promise<Unit> &&promise) {
+  string short_name = clean_username(short_name_to_search);
+  auto it = short_name_to_sticker_set_id_.find(short_name);
+  const StickerSet *sticker_set = it == short_name_to_sticker_set_id_.end() ? nullptr : get_sticker_set(it->second);
+
+  if (sticker_set == nullptr) {
+    auto set_to_load = make_tl_object<telegram_api::inputStickerSetShortName>(short_name);
+    reload_sticker_set(0, std::move(set_to_load), std::move(promise));
+    return 0;
+  }
+
+  if (update_sticker_set_cache(sticker_set, promise)) {
+    return 0;
+  }
+
+  promise.set_value(Unit());
+  return sticker_set->id;
+}
+
+std::pair<int32, vector<int64>> StickersManager::search_installed_sticker_sets(bool is_masks, const string &query,
+                                                                               int32 limit, Promise<Unit> &&promise) {
+  LOG(INFO) << "Search installed " << (is_masks ? "masks " : "") << "sticker sets with query = \"" << query
+            << "\" and limit = " << limit;
+
+  if (limit < 0) {
+    promise.set_error(Status::Error(400, "Limit must be non-negative"));
+    return {};
+  }
+
+  if (!are_installed_sticker_sets_loaded_[is_masks]) {
+    load_installed_sticker_sets(is_masks, std::move(promise));
+    return {};
+  }
+  reload_installed_sticker_sets(is_masks, false);
+
+  std::pair<size_t, vector<int64>> result = installed_sticker_sets_hints_[is_masks].search(query, limit);
+  promise.set_value(Unit());
+  return {narrow_cast<int32>(result.first), std::move(result.second)};
+}
+
+vector<int64> StickersManager::search_sticker_sets(const string &query, Promise<Unit> &&promise) {
+  auto q = clean_name(query, 1000);
+  auto it = found_sticker_sets_.find(q);
+  if (it != found_sticker_sets_.end()) {
+    promise.set_value(Unit());
+    return it->second;
+  }
+
+  auto &promises = search_sticker_sets_queries_[q];
+  promises.push_back(std::move(promise));
+  if (promises.size() == 1u) {
+    td_->create_handler<SearchStickerSetsQuery>()->send(std::move(q));
+  }
+
+  return {};
+}
+
+void StickersManager::on_find_sticker_sets_success(
+    const string &query, tl_object_ptr<telegram_api::messages_FoundStickerSets> &&sticker_sets) {
+  CHECK(sticker_sets != nullptr);
+  switch (sticker_sets->get_id()) {
+    case telegram_api::messages_foundStickerSetsNotModified::ID:
+      return on_find_sticker_sets_fail(query, Status::Error(500, "Receive messages.foundStickerSetsNotModified"));
+    case telegram_api::messages_foundStickerSets::ID: {
+      auto found_stickers_sets = move_tl_object_as<telegram_api::messages_foundStickerSets>(sticker_sets);
+      vector<int64> &sticker_set_ids = found_sticker_sets_[query];
+      CHECK(sticker_set_ids.empty());
+
+      for (auto &sticker_set : found_stickers_sets->sets_) {
+        int64 set_id = on_get_sticker_set_covered(std::move(sticker_set), true);
+        if (set_id == 0) {
+          continue;
+        }
+
+        update_sticker_set(get_sticker_set(set_id));
+        sticker_set_ids.push_back(set_id);
+      }
+
+      send_update_installed_sticker_sets();
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+
+  auto it = search_sticker_sets_queries_.find(query);
+  CHECK(it != search_sticker_sets_queries_.end());
+  CHECK(!it->second.empty());
+  auto promises = std::move(it->second);
+  search_sticker_sets_queries_.erase(it);
+
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+void StickersManager::on_find_sticker_sets_fail(const string &query, Status &&error) {
+  CHECK(found_sticker_sets_.count(query) == 0);
+
+  auto it = search_sticker_sets_queries_.find(query);
+  CHECK(it != search_sticker_sets_queries_.end());
+  CHECK(!it->second.empty());
+  auto promises = std::move(it->second);
+  search_sticker_sets_queries_.erase(it);
+
+  for (auto &promise : promises) {
+    promise.set_error(error.clone());
+  }
+}
+
+void StickersManager::change_sticker_set(int64 set_id, bool is_installed, bool is_archived, Promise<Unit> &&promise) {
+  if (is_installed && is_archived) {
+    return promise.set_error(Status::Error(400, "Sticker set can't be installed and archived simultaneously"));
+  }
+  const StickerSet *sticker_set = get_sticker_set(set_id);
+  if (sticker_set == nullptr) {
+    return promise.set_error(Status::Error(400, "Sticker set not found"));
+  }
+  if (!sticker_set->is_inited) {
+    load_sticker_sets({set_id}, std::move(promise));
+    return;
+  }
+  if (!are_installed_sticker_sets_loaded_[sticker_set->is_masks]) {
+    load_installed_sticker_sets(sticker_set->is_masks, std::move(promise));
+    return;
+  }
+
+  if (is_archived) {
+    is_installed = true;
+  }
+  if (is_installed) {
+    if (sticker_set->is_installed && is_archived == sticker_set->is_archived) {
+      return promise.set_value(Unit());
+    }
+
+    td_->create_handler<InstallStickerSetQuery>(std::move(promise))
+        ->send(set_id, get_input_sticker_set(sticker_set), is_archived);
+    return;
+  }
+
+  if (!sticker_set->is_installed) {
+    return promise.set_value(Unit());
+  }
+
+  td_->create_handler<UninstallStickerSetQuery>(std::move(promise))->send(set_id, get_input_sticker_set(sticker_set));
+}
+
+void StickersManager::on_update_sticker_set(StickerSet *sticker_set, bool is_installed, bool is_archived,
+                                            bool is_changed, bool from_database) {
+  LOG(INFO) << "Update sticker set " << sticker_set->id << ": installed = " << is_installed
+            << ", archived = " << is_archived << ", changed = " << is_changed;
+  CHECK(sticker_set->is_inited);
+  if (is_archived) {
+    is_installed = true;
+  }
+  if (sticker_set->is_installed == is_installed && sticker_set->is_archived == is_archived) {
+    return;
+  }
+
+  bool was_added = sticker_set->is_installed && !sticker_set->is_archived;
+  bool was_archived = sticker_set->is_archived;
+  sticker_set->is_installed = is_installed;
+  sticker_set->is_archived = is_archived;
+  if (!from_database) {
+    sticker_set->is_changed = true;
+  }
+
+  bool is_added = sticker_set->is_installed && !sticker_set->is_archived;
+  if (was_added != is_added) {
+    vector<int64> &sticker_set_ids = installed_sticker_set_ids_[sticker_set->is_masks];
+    need_update_installed_sticker_sets_[sticker_set->is_masks] = true;
+
+    if (is_added) {
+      installed_sticker_sets_hints_[sticker_set->is_masks].add(sticker_set->id,
+                                                               sticker_set->title + " " + sticker_set->short_name);
+      sticker_set_ids.insert(sticker_set_ids.begin(), sticker_set->id);
+    } else {
+      installed_sticker_sets_hints_[sticker_set->is_masks].remove(sticker_set->id);
+      sticker_set_ids.erase(std::remove(sticker_set_ids.begin(), sticker_set_ids.end(), sticker_set->id),
+                            sticker_set_ids.end());
+    }
+  }
+  if (was_archived != is_archived && is_changed) {
+    int32 &total_count = total_archived_sticker_set_count_[sticker_set->is_masks];
+    vector<int64> &sticker_set_ids = archived_sticker_set_ids_[sticker_set->is_masks];
+    if (total_count < 0) {
+      return;
+    }
+
+    if (is_archived) {
+      total_count++;
+      sticker_set_ids.insert(sticker_set_ids.begin(), sticker_set->id);
+    } else {
+      total_count--;
+      sticker_set_ids.erase(std::remove(sticker_set_ids.begin(), sticker_set_ids.end(), sticker_set->id),
+                            sticker_set_ids.end());
+    }
+  }
+}
+
+void StickersManager::load_installed_sticker_sets(bool is_masks, Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    are_installed_sticker_sets_loaded_[is_masks] = true;
+  }
+  if (are_installed_sticker_sets_loaded_[is_masks]) {
+    promise.set_value(Unit());
+    return;
+  }
+  load_installed_sticker_sets_queries_[is_masks].push_back(std::move(promise));
+  if (load_installed_sticker_sets_queries_[is_masks].size() == 1u) {
+    if (G()->parameters().use_file_db) {
+      LOG(INFO) << "Trying to load installed " << (is_masks ? "masks " : "") << "sticker sets from database";
+      G()->td_db()->get_sqlite_pmc()->get(is_masks ? "sss1" : "sss0", PromiseCreator::lambda([is_masks](string value) {
+                                            send_closure(G()->stickers_manager(),
+                                                         &StickersManager::on_load_installed_sticker_sets_from_database,
+                                                         is_masks, std::move(value));
+                                          }));
+    } else {
+      LOG(INFO) << "Trying to load installed " << (is_masks ? "masks " : "") << "sticker sets from server";
+      reload_installed_sticker_sets(is_masks, true);
+    }
+  }
+}
+
+void StickersManager::on_load_installed_sticker_sets_from_database(bool is_masks, string value) {
+  if (value.empty()) {
+    LOG(INFO) << "Installed " << (is_masks ? "mask " : "") << "sticker sets aren't found in database";
+    reload_installed_sticker_sets(is_masks, true);
+    return;
+  }
+
+  LOG(INFO) << "Successfully loaded installed " << (is_masks ? "mask " : "") << "sticker sets list of size "
+            << value.size() << " from database";
+
+  StickerSetListLogEvent log_event;
+  log_event_parse(log_event, value).ensure();
+
+  vector<int64> sets_to_load;
+  for (auto sticker_set_id : log_event.sticker_set_ids) {
+    StickerSet *sticker_set = get_sticker_set(sticker_set_id);
+    CHECK(sticker_set != nullptr);
+    if (!sticker_set->is_inited) {
+      sets_to_load.push_back(sticker_set_id);
+    }
+  }
+  std::reverse(sets_to_load.begin(), sets_to_load.end());  // load installed sticker sets in reverse order
+
+  load_sticker_sets_without_stickers(
+      std::move(sets_to_load),
+      PromiseCreator::lambda(
+          [is_masks, sticker_set_ids = std::move(log_event.sticker_set_ids)](Result<> result) mutable {
+            if (result.is_ok()) {
+              send_closure(G()->stickers_manager(), &StickersManager::on_load_installed_sticker_sets_finished, is_masks,
+                           std::move(sticker_set_ids), true);
+            }
+          }));
+}
+
+void StickersManager::on_load_installed_sticker_sets_finished(bool is_masks, vector<int64> &&installed_sticker_set_ids,
+                                                              bool from_database) {
+  bool need_reload = false;
+  vector<int64> old_installed_sticker_set_ids;
+  if (!are_installed_sticker_sets_loaded_[is_masks] && !installed_sticker_set_ids_[is_masks].empty()) {
+    old_installed_sticker_set_ids = std::move(installed_sticker_set_ids_[is_masks]);
+  }
+  installed_sticker_set_ids_[is_masks].clear();
+  for (auto set_id : installed_sticker_set_ids) {
+    CHECK(set_id != 0);
+
+    auto sticker_set = get_sticker_set(set_id);
+    CHECK(sticker_set != nullptr);
+    CHECK(sticker_set->is_inited);
+    CHECK(sticker_set->is_masks == is_masks);
+    if (sticker_set->is_installed && !sticker_set->is_archived) {
+      installed_sticker_set_ids_[is_masks].push_back(set_id);
+    } else {
+      need_reload = true;
+    }
+  }
+  if (need_reload) {
+    LOG(ERROR) << "Reload installed " << (is_masks ? "masks " : "") << "sticker sets, because only "
+               << installed_sticker_set_ids_[is_masks].size() << " of " << installed_sticker_set_ids.size()
+               << " are really installed";
+    reload_installed_sticker_sets(is_masks, true);
+  } else if (!old_installed_sticker_set_ids.empty() &&
+             old_installed_sticker_set_ids != installed_sticker_set_ids_[is_masks]) {
+    LOG(ERROR) << "Reload installed " << (is_masks ? "masks " : "") << "sticker sets, because they has changed from "
+               << old_installed_sticker_set_ids << " to " << installed_sticker_set_ids_[is_masks];
+    reload_installed_sticker_sets(is_masks, true);
+  }
+
+  are_installed_sticker_sets_loaded_[is_masks] = true;
+  need_update_installed_sticker_sets_[is_masks] = true;
+  send_update_installed_sticker_sets(from_database);
+  auto promises = std::move(load_installed_sticker_sets_queries_[is_masks]);
+  load_installed_sticker_sets_queries_[is_masks].clear();
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+string StickersManager::get_sticker_set_database_key(int64 set_id) {
+  return "ss" + to_string(set_id);
+}
+
+string StickersManager::get_full_sticker_set_database_key(int64 set_id) {
+  return "ssf" + to_string(set_id);
+}
+
+string StickersManager::get_sticker_set_database_value(const StickerSet *s, bool with_stickers) {
+  LogEventStorerCalcLength storer_calc_length;
+  store_sticker_set(s, with_stickers, storer_calc_length);
+
+  BufferSlice value_buffer{storer_calc_length.get_length()};
+  auto value = value_buffer.as_slice();
+
+  LOG(DEBUG) << "Sticker set " << s->id << " serialized size is " << value.size();
+
+  LogEventStorerUnsafe storer_unsafe(value.begin());
+  store_sticker_set(s, with_stickers, storer_unsafe);
+
+  return value.str();
+}
+
+void StickersManager::update_sticker_set(StickerSet *sticker_set) {
+  CHECK(sticker_set != nullptr);
+  if (sticker_set->is_changed) {
+    sticker_set->is_changed = false;
+    if (G()->parameters().use_file_db) {
+      LOG(INFO) << "Save sticker set " << sticker_set->id << " to database";
+      if (sticker_set->is_inited) {
+        G()->td_db()->get_sqlite_pmc()->set(get_sticker_set_database_key(sticker_set->id),
+                                            get_sticker_set_database_value(sticker_set, false), Auto());
+      }
+      if (sticker_set->was_loaded) {
+        G()->td_db()->get_sqlite_pmc()->set(get_full_sticker_set_database_key(sticker_set->id),
+                                            get_sticker_set_database_value(sticker_set, true), Auto());
+      }
+    }
+    if (sticker_set->is_inited) {
+      update_load_requests(sticker_set, false, Status::OK());
+    }
+  }
+}
+
+void StickersManager::load_sticker_sets(vector<int64> &&sticker_set_ids, Promise<Unit> &&promise) {
+  if (sticker_set_ids.empty()) {
+    promise.set_value(Unit());
+    return;
+  }
+
+  auto load_request_id = current_sticker_set_load_request_++;
+  StickerSetLoadRequest &load_request = sticker_set_load_requests_[load_request_id];
+  load_request.promise = std::move(promise);
+  load_request.left_queries = sticker_set_ids.size();
+
+  for (auto sticker_set_id : sticker_set_ids) {
+    StickerSet *sticker_set = get_sticker_set(sticker_set_id);
+    CHECK(sticker_set != nullptr);
+    CHECK(!sticker_set->is_loaded);
+
+    sticker_set->load_requests.push_back(load_request_id);
+    if (sticker_set->load_requests.size() == 1u) {
+      if (G()->parameters().use_file_db && !sticker_set->was_loaded) {
+        LOG(INFO) << "Trying to load sticker set " << sticker_set_id << " with stickers from database";
+        G()->td_db()->get_sqlite_pmc()->get(
+            get_full_sticker_set_database_key(sticker_set_id), PromiseCreator::lambda([sticker_set_id](string value) {
+              send_closure(G()->stickers_manager(), &StickersManager::on_load_sticker_set_from_database, sticker_set_id,
+                           true, std::move(value));
+            }));
+      } else {
+        LOG(INFO) << "Trying to load sticker set " << sticker_set_id << " with stickers from server";
+        reload_sticker_set(sticker_set_id, get_input_sticker_set(sticker_set), Auto());
+      }
+    }
+  }
+}
+
+void StickersManager::load_sticker_sets_without_stickers(vector<int64> &&sticker_set_ids, Promise<Unit> &&promise) {
+  if (sticker_set_ids.empty()) {
+    promise.set_value(Unit());
+    return;
+  }
+
+  auto load_request_id = current_sticker_set_load_request_++;
+  StickerSetLoadRequest &load_request = sticker_set_load_requests_[load_request_id];
+  load_request.promise = std::move(promise);
+  load_request.left_queries = sticker_set_ids.size();
+
+  for (auto sticker_set_id : sticker_set_ids) {
+    StickerSet *sticker_set = get_sticker_set(sticker_set_id);
+    CHECK(sticker_set != nullptr);
+    CHECK(!sticker_set->is_inited);
+
+    if (!sticker_set->load_requests.empty()) {
+      sticker_set->load_requests.push_back(load_request_id);
+    } else {
+      sticker_set->load_without_stickers_requests.push_back(load_request_id);
+      if (sticker_set->load_without_stickers_requests.size() == 1u) {
+        if (G()->parameters().use_file_db) {
+          LOG(INFO) << "Trying to load sticker set " << sticker_set_id << " from database";
+          G()->td_db()->get_sqlite_pmc()->get(
+              get_sticker_set_database_key(sticker_set_id), PromiseCreator::lambda([sticker_set_id](string value) {
+                send_closure(G()->stickers_manager(), &StickersManager::on_load_sticker_set_from_database,
+                             sticker_set_id, false, std::move(value));
+              }));
+        } else {
+          LOG(INFO) << "Trying to load sticker set " << sticker_set_id << " from server";
+          reload_sticker_set(sticker_set_id, get_input_sticker_set(sticker_set), Auto());
+        }
+      }
+    }
+  }
+}
+
+void StickersManager::on_load_sticker_set_from_database(int64 sticker_set_id, bool with_stickers, string value) {
+  StickerSet *sticker_set = get_sticker_set(sticker_set_id);
+  CHECK(sticker_set != nullptr);
+  if (sticker_set->was_loaded) {
+    LOG(INFO) << "Sticker set " << sticker_set_id << " was loaded";
+    return;
+  }
+  if (!with_stickers && sticker_set->is_inited) {
+    LOG(INFO) << "Sticker set " << sticker_set_id << " was inited";
+    return;
+  }
+
+  if (with_stickers) {
+    CHECK(!sticker_set->load_requests.empty());
+  } else {
+    CHECK(!sticker_set->load_without_stickers_requests.empty());
+  }
+  if (value.empty()) {
+    reload_sticker_set(sticker_set_id, get_input_sticker_set(sticker_set), Auto());
+    return;
+  }
+
+  LOG(INFO) << "Successfully loaded sticker set " << sticker_set_id << " with" << (with_stickers ? "" : "out")
+            << " stickers of size " << value.size() << " from database";
+
+  auto old_sticker_count = sticker_set->sticker_ids.size();
+
+  {
+    LOG_IF(ERROR, sticker_set->is_changed) << "Sticker set with" << (with_stickers ? "" : "out") << " stickers "
+                                           << sticker_set_id << " was changed before it is loaded from database";
+    LogEventParser parser(value);
+    parse_sticker_set(sticker_set, parser);
+    LOG_IF(ERROR, sticker_set->is_changed)
+        << "Sticker set with" << (with_stickers ? "" : "out") << " stickers " << sticker_set_id << " is changed";
+    parser.fetch_end();
+    parser.get_status().ensure();
+  }
+
+  if (with_stickers && old_sticker_count < 5 && old_sticker_count < sticker_set->sticker_ids.size()) {
+    sticker_set->is_changed = true;
+    update_sticker_set(sticker_set);
+  }
+
+  update_load_requests(sticker_set, with_stickers, Status::OK());
+}
+
+void StickersManager::reload_sticker_set(int64 sticker_set_id,
+                                         tl_object_ptr<telegram_api::InputStickerSet> &&input_sticker_set,
+                                         Promise<Unit> &&promise) const {
+  td_->create_handler<GetStickerSetQuery>(std::move(promise))->send(sticker_set_id, std::move(input_sticker_set));
+}
+
+void StickersManager::on_install_sticker_set(int64 set_id, bool is_archived,
+                                             tl_object_ptr<telegram_api::messages_StickerSetInstallResult> &&result) {
+  StickerSet *sticker_set = get_sticker_set(set_id);
+  CHECK(sticker_set != nullptr);
+  on_update_sticker_set(sticker_set, true, is_archived, true);
+  update_sticker_set(sticker_set);
+
+  switch (result->get_id()) {
+    case telegram_api::messages_stickerSetInstallResultSuccess::ID:
+      break;
+    case telegram_api::messages_stickerSetInstallResultArchive::ID: {
+      auto archived_sets = move_tl_object_as<telegram_api::messages_stickerSetInstallResultArchive>(result);
+      for (auto &archived_set_ptr : archived_sets->sets_) {
+        int64 archived_sticker_set_id = on_get_sticker_set_covered(std::move(archived_set_ptr), true);
+        if (archived_sticker_set_id != 0) {
+          auto archived_sticker_set = get_sticker_set(archived_sticker_set_id);
+          CHECK(archived_sticker_set != nullptr);
+          update_sticker_set(archived_sticker_set);
+        }
+      }
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+
+  send_update_installed_sticker_sets();
+}
+
+void StickersManager::on_uninstall_sticker_set(int64 set_id) {
+  StickerSet *sticker_set = get_sticker_set(set_id);
+  CHECK(sticker_set != nullptr);
+  on_update_sticker_set(sticker_set, false, false, true);
+  update_sticker_set(sticker_set);
+  send_update_installed_sticker_sets();
+}
+
+void StickersManager::on_update_sticker_sets() {
+  // TODO better support
+  archived_sticker_set_ids_[0].clear();
+  total_archived_sticker_set_count_[0] = -1;
+  reload_installed_sticker_sets(false, true);
+
+  archived_sticker_set_ids_[1].clear();
+  total_archived_sticker_set_count_[1] = -1;
+  reload_installed_sticker_sets(true, true);
+}
+
+void StickersManager::view_featured_sticker_sets(const vector<int64> &sticker_set_ids) {
+  for (auto sticker_set_id : sticker_set_ids) {
+    auto set = get_sticker_set(sticker_set_id);
+    if (set != nullptr && !set->is_viewed) {
+      need_update_featured_sticker_sets_ = true;
+      set->is_viewed = true;
+      pending_viewed_featured_sticker_set_ids_.insert(sticker_set_id);
+      update_sticker_set(set);
+    }
+  }
+
+  send_update_featured_sticker_sets();
+
+  if (!pending_viewed_featured_sticker_set_ids_.empty() && !pending_featured_sticker_set_views_timeout_.has_timeout()) {
+    LOG(INFO) << "Have pending viewed featured sticker sets";
+    pending_featured_sticker_set_views_timeout_.set_callback(read_featured_sticker_sets);
+    pending_featured_sticker_set_views_timeout_.set_callback_data(static_cast<void *>(td_));
+    pending_featured_sticker_set_views_timeout_.set_timeout_in(MAX_FEATURED_STICKER_SET_VIEW_DELAY);
+  }
+}
+
+void StickersManager::read_featured_sticker_sets(void *td_void) {
+  CHECK(td_void != nullptr);
+  auto td = static_cast<Td *>(td_void);
+
+  auto &set_ids = td->stickers_manager_->pending_viewed_featured_sticker_set_ids_;
+  td->create_handler<ReadFeaturedStickerSetsQuery>()->send(vector<int64>(set_ids.begin(), set_ids.end()));
+  set_ids.clear();
+}
+
+std::pair<int32, vector<int64>> StickersManager::get_archived_sticker_sets(bool is_masks, int64 offset_sticker_set_id,
+                                                                           int32 limit, bool force,
+                                                                           Promise<Unit> &&promise) {
+  if (limit <= 0) {
+    promise.set_error(Status::Error(3, "Parameter limit must be positive"));
+    return {};
+  }
+
+  vector<int64> &sticker_set_ids = archived_sticker_set_ids_[is_masks];
+  int32 total_count = total_archived_sticker_set_count_[is_masks];
+  if (total_count < 0) {
+    total_count = 0;
+  }
+
+  if (!sticker_set_ids.empty()) {
+    auto offset_it = sticker_set_ids.begin();
+    if (offset_sticker_set_id != 0) {
+      offset_it = std::find(sticker_set_ids.begin(), sticker_set_ids.end(), offset_sticker_set_id);
+      if (offset_it == sticker_set_ids.end()) {
+        offset_it = sticker_set_ids.begin();
+      } else {
+        ++offset_it;
+      }
+    }
+    vector<int64> result;
+    while (result.size() < static_cast<size_t>(limit)) {
+      if (offset_it == sticker_set_ids.end()) {
+        break;
+      }
+      auto sticker_set_id = *offset_it++;
+      if (sticker_set_id == 0) {  // end of the list
+        promise.set_value(Unit());
+        return {total_count, std::move(result)};
+      }
+      result.push_back(sticker_set_id);
+    }
+    if (result.size() == static_cast<size_t>(limit) || force) {
+      promise.set_value(Unit());
+      return {total_count, std::move(result)};
+    }
+  }
+
+  td_->create_handler<GetArchivedStickerSetsQuery>(std::move(promise))->send(is_masks, offset_sticker_set_id, limit);
+  return {};
+}
+
+void StickersManager::on_get_archived_sticker_sets(
+    bool is_masks, vector<tl_object_ptr<telegram_api::StickerSetCovered>> &&sticker_sets, int32 total_count) {
+  vector<int64> &sticker_set_ids = archived_sticker_set_ids_[is_masks];
+  if (sticker_set_ids.size() > 0 && sticker_set_ids.back() == 0) {
+    return;
+  }
+
+  total_archived_sticker_set_count_[is_masks] = total_count;
+  for (auto &sticker_set_covered : sticker_sets) {
+    auto sticker_set_id = on_get_sticker_set_covered(std::move(sticker_set_covered), false);
+    if (sticker_set_id != 0) {
+      auto sticker_set = get_sticker_set(sticker_set_id);
+      CHECK(sticker_set != nullptr);
+      update_sticker_set(sticker_set);
+
+      if (std::find(sticker_set_ids.begin(), sticker_set_ids.end(), sticker_set_id) == sticker_set_ids.end()) {
+        sticker_set_ids.push_back(sticker_set_id);
+      }
+    }
+  }
+  if (sticker_set_ids.size() >= static_cast<size_t>(total_count)) {
+    if (sticker_set_ids.size() > static_cast<size_t>(total_count)) {
+      LOG(ERROR) << "Expected total of " << total_count << " archived sticker sets, but only " << sticker_set_ids.size()
+                 << " found";
+      total_archived_sticker_set_count_[is_masks] = static_cast<int32>(sticker_set_ids.size());
+    }
+    sticker_set_ids.push_back(0);
+  }
+  send_update_installed_sticker_sets();
+}
+
+vector<int64> StickersManager::get_featured_sticker_sets(Promise<Unit> &&promise) {
+  if (!are_featured_sticker_sets_loaded_) {
+    load_featured_sticker_sets(std::move(promise));
+    return {};
+  }
+  reload_featured_sticker_sets(false);
+
+  promise.set_value(Unit());
+  return featured_sticker_set_ids_;
+}
+
+void StickersManager::on_get_featured_sticker_sets(
+    tl_object_ptr<telegram_api::messages_FeaturedStickers> &&sticker_sets_ptr) {
+  next_featured_sticker_sets_load_time_ = Time::now_cached() + Random::fast(30 * 60, 50 * 60);
+
+  int32 constructor_id = sticker_sets_ptr->get_id();
+  if (constructor_id == telegram_api::messages_featuredStickersNotModified::ID) {
+    LOG(INFO) << "Featured stickers are not modified";
+    return;
+  }
+  CHECK(constructor_id == telegram_api::messages_featuredStickers::ID);
+  auto featured_stickers = move_tl_object_as<telegram_api::messages_featuredStickers>(sticker_sets_ptr);
+
+  vector<int64> featured_sticker_set_ids;
+  std::unordered_set<int64> unread_sticker_set_ids(featured_stickers->unread_.begin(),
+                                                   featured_stickers->unread_.end());
+  for (auto &sticker_set : featured_stickers->sets_) {
+    int64 set_id = on_get_sticker_set_covered(std::move(sticker_set), true);
+    if (set_id == 0) {
+      continue;
+    }
+
+    auto set = get_sticker_set(set_id);
+    CHECK(set != nullptr);
+    bool is_viewed = unread_sticker_set_ids.count(set_id) == 0;
+    if (is_viewed != set->is_viewed) {
+      set->is_viewed = is_viewed;
+      set->is_changed = true;
+    }
+
+    update_sticker_set(set);
+
+    featured_sticker_set_ids.push_back(set_id);
+  }
+
+  send_update_installed_sticker_sets();
+
+  on_load_featured_sticker_sets_finished(std::move(featured_sticker_set_ids));
+
+  LOG_IF(ERROR, featured_sticker_sets_hash_ != featured_stickers->hash_) << "Featured sticker sets hash mismatch";
+
+  if (!G()->parameters().use_file_db) {
+    return;
+  }
+
+  LOG(INFO) << "Save featured sticker sets to database";
+  StickerSetListLogEvent log_event(featured_sticker_set_ids_);
+  G()->td_db()->get_sqlite_pmc()->set("sssfeatured", log_event_store(log_event).as_slice().str(), Auto());
+}
+
+void StickersManager::on_get_featured_sticker_sets_failed(Status error) {
+  CHECK(error.is_error());
+  next_featured_sticker_sets_load_time_ = Time::now_cached() + Random::fast(5, 10);
+  auto promises = std::move(load_featured_sticker_sets_queries_);
+  load_featured_sticker_sets_queries_.clear();
+  for (auto &promise : promises) {
+    promise.set_error(error.clone());
+  }
+}
+
+void StickersManager::load_featured_sticker_sets(Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    are_featured_sticker_sets_loaded_ = true;
+  }
+  if (are_featured_sticker_sets_loaded_) {
+    promise.set_value(Unit());
+    return;
+  }
+  load_featured_sticker_sets_queries_.push_back(std::move(promise));
+  if (load_featured_sticker_sets_queries_.size() == 1u) {
+    if (G()->parameters().use_file_db) {
+      LOG(INFO) << "Trying to load featured sticker sets from database";
+      G()->td_db()->get_sqlite_pmc()->get("sssfeatured", PromiseCreator::lambda([](string value) {
+                                            send_closure(G()->stickers_manager(),
+                                                         &StickersManager::on_load_featured_sticker_sets_from_database,
+                                                         std::move(value));
+                                          }));
+    } else {
+      LOG(INFO) << "Trying to load featured sticker sets from server";
+      reload_featured_sticker_sets(true);
+    }
+  }
+}
+
+void StickersManager::on_load_featured_sticker_sets_from_database(string value) {
+  if (value.empty()) {
+    LOG(INFO) << "Featured sticker sets aren't found in database";
+    reload_featured_sticker_sets(true);
+    return;
+  }
+
+  LOG(INFO) << "Successfully loaded featured sticker sets list of size " << value.size() << " from database";
+
+  StickerSetListLogEvent log_event;
+  log_event_parse(log_event, value).ensure();
+
+  vector<int64> sets_to_load;
+  for (auto sticker_set_id : log_event.sticker_set_ids) {
+    StickerSet *sticker_set = get_sticker_set(sticker_set_id);
+    CHECK(sticker_set != nullptr);
+    if (!sticker_set->is_inited) {
+      sets_to_load.push_back(sticker_set_id);
+    }
+  }
+
+  load_sticker_sets_without_stickers(
+      std::move(sets_to_load),
+      PromiseCreator::lambda([sticker_set_ids = std::move(log_event.sticker_set_ids)](Result<> result) mutable {
+        if (result.is_ok()) {
+          send_closure(G()->stickers_manager(), &StickersManager::on_load_featured_sticker_sets_finished,
+                       std::move(sticker_set_ids));
+        }
+      }));
+}
+
+void StickersManager::on_load_featured_sticker_sets_finished(vector<int64> &&featured_sticker_set_ids) {
+  featured_sticker_set_ids_ = std::move(featured_sticker_set_ids);
+  are_featured_sticker_sets_loaded_ = true;
+  need_update_featured_sticker_sets_ = true;
+  send_update_featured_sticker_sets();
+  auto promises = std::move(load_featured_sticker_sets_queries_);
+  load_featured_sticker_sets_queries_.clear();
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+vector<int64> StickersManager::get_attached_sticker_sets(FileId file_id, Promise<Unit> &&promise) {
+  if (!file_id.is_valid()) {
+    promise.set_error(Status::Error(5, "Wrong file_id specified"));
+    return {};
+  }
+
+  auto file_view = td_->file_manager_->get_file_view(file_id);
+  if (file_view.empty()) {
+    promise.set_error(Status::Error(5, "File not found"));
+    return {};
+  }
+  if (!file_view.has_remote_location() || file_view.remote_location().is_encrypted() ||
+      file_view.remote_location().is_web()) {
+    promise.set_value(Unit());
+    return {};
+  }
+
+  auto it = attached_sticker_sets_.find(file_id);
+  if (it != attached_sticker_sets_.end()) {
+    promise.set_value(Unit());
+    return it->second;
+  }
+
+  tl_object_ptr<telegram_api::InputStickeredMedia> input_stickered_media;
+  if (file_view.remote_location().is_photo()) {
+    input_stickered_media =
+        make_tl_object<telegram_api::inputStickeredMediaPhoto>(file_view.remote_location().as_input_photo());
+  } else {
+    input_stickered_media =
+        make_tl_object<telegram_api::inputStickeredMediaDocument>(file_view.remote_location().as_input_document());
+  }
+
+  td_->create_handler<GetAttachedStickerSetsQuery>(std::move(promise))->send(file_id, std::move(input_stickered_media));
+  return {};
+}
+
+void StickersManager::on_get_attached_sticker_sets(
+    FileId file_id, vector<tl_object_ptr<telegram_api::StickerSetCovered>> &&sticker_sets) {
+  vector<int64> &sticker_set_ids = attached_sticker_sets_[file_id];
+  sticker_set_ids.clear();
+  for (auto &sticker_set_covered : sticker_sets) {
+    auto sticker_set_id = on_get_sticker_set_covered(std::move(sticker_set_covered), true);
+    if (sticker_set_id != 0) {
+      auto sticker_set = get_sticker_set(sticker_set_id);
+      CHECK(sticker_set != nullptr);
+      update_sticker_set(sticker_set);
+
+      sticker_set_ids.push_back(sticker_set_id);
+    }
+  }
+  send_update_installed_sticker_sets();
+}
+
+// -1 - order can't be applied, because some sticker sets aren't loaded or aren't installed,
+// 0 - order wasn't changed, 1 - order was partly replaced by the new order, 2 - order was replaced by the new order
+int StickersManager::apply_installed_sticker_sets_order(bool is_masks, const vector<int64> &sticker_set_ids) {
+  if (!are_installed_sticker_sets_loaded_[is_masks]) {
+    return -1;
+  }
+
+  vector<int64> &current_sticker_set_ids = installed_sticker_set_ids_[is_masks];
+  if (sticker_set_ids == current_sticker_set_ids) {
+    return 0;
+  }
+
+  std::unordered_set<int64> valid_set_ids(current_sticker_set_ids.begin(), current_sticker_set_ids.end());
+  vector<int64> new_sticker_set_ids;
+  for (auto sticker_set_id : sticker_set_ids) {
+    auto it = valid_set_ids.find(sticker_set_id);
+    if (it != valid_set_ids.end()) {
+      new_sticker_set_ids.push_back(sticker_set_id);
+      valid_set_ids.erase(it);
+    } else {
+      return -1;
+    }
+  }
+  if (new_sticker_set_ids.empty()) {
+    return 0;
+  }
+  if (!valid_set_ids.empty()) {
+    vector<int64> missed_sticker_set_ids;
+    for (auto sticker_set_id : current_sticker_set_ids) {
+      auto it = valid_set_ids.find(sticker_set_id);
+      if (it != valid_set_ids.end()) {
+        missed_sticker_set_ids.push_back(sticker_set_id);
+        valid_set_ids.erase(it);
+      }
+    }
+    append(missed_sticker_set_ids, new_sticker_set_ids);
+    new_sticker_set_ids = std::move(missed_sticker_set_ids);
+  }
+  CHECK(valid_set_ids.empty());
+
+  if (new_sticker_set_ids == current_sticker_set_ids) {
+    return 0;
+  }
+  current_sticker_set_ids = std::move(new_sticker_set_ids);
+
+  need_update_installed_sticker_sets_[is_masks] = true;
+  if (sticker_set_ids != current_sticker_set_ids) {
+    return 1;
+  }
+  return 2;
+}
+
+void StickersManager::on_update_sticker_sets_order(bool is_masks, const vector<int64> &sticker_set_ids) {
+  int result = apply_installed_sticker_sets_order(is_masks, sticker_set_ids);
+  if (result < 0) {
+    return reload_installed_sticker_sets(is_masks, true);
+  }
+  if (result > 0) {
+    send_update_installed_sticker_sets();
+  }
+}
+
+void StickersManager::reorder_installed_sticker_sets(bool is_masks, const vector<int64> &sticker_set_ids,
+                                                     Promise<Unit> &&promise) {
+  auto result = apply_installed_sticker_sets_order(is_masks, sticker_set_ids);
+  if (result < 0) {
+    return promise.set_error(Status::Error(400, "Wrong sticker set list"));
+  }
+  if (result > 0) {
+    td_->create_handler<ReorderStickerSetsQuery>()->send(is_masks, installed_sticker_set_ids_[is_masks]);
+    send_update_installed_sticker_sets();
+  }
+  promise.set_value(Unit());
+}
+
+Result<std::tuple<FileId, bool, bool>> StickersManager::prepare_input_sticker(td_api::inputSticker *sticker) {
+  if (sticker == nullptr) {
+    return Status::Error(3, "Input sticker shouldn't be empty");
+  }
+
+  if (!clean_input_string(sticker->emojis_)) {
+    return Status::Error(400, "Emojis must be encoded in UTF-8");
+  }
+
+  return prepare_input_file(sticker->png_sticker_);
+}
+
+Result<std::tuple<FileId, bool, bool>> StickersManager::prepare_input_file(
+    const tl_object_ptr<td_api::InputFile> &input_file) {
+  auto r_file_id = td_->file_manager_->get_input_file_id(FileType::Document, input_file, {}, false, false, false);
+  if (r_file_id.is_error()) {
+    return Status::Error(7, r_file_id.error().message());
+  }
+  auto file_id = r_file_id.move_as_ok();
+
+  td_->documents_manager_->create_document(file_id, PhotoSize(), "sticker.png", "image/png", false);
+
+  FileView file_view = td_->file_manager_->get_file_view(file_id);
+  if (file_view.is_encrypted()) {
+    return Status::Error(400, "Can't use encrypted file");
+  }
+
+  if (file_view.has_remote_location() && file_view.remote_location().is_web()) {
+    return Status::Error(400, "Can't use web file to create a sticker");
+  }
+  bool is_url = false;
+  bool is_local = false;
+  if (file_view.has_remote_location()) {
+    CHECK(!file_view.remote_location().is_encrypted());
+    CHECK(!file_view.remote_location().is_photo());
+  } else {
+    if (file_view.has_url()) {
+      is_url = true;
+    } else {
+      if (file_view.has_local_location() && file_view.local_size() > MAX_STICKER_FILE_SIZE) {
+        return Status::Error(400, "File is too big");
+      }
+      is_local = true;
+    }
+  }
+  return std::make_tuple(file_id, is_url, is_local);
+}
+
+FileId StickersManager::upload_sticker_file(UserId user_id, const tl_object_ptr<td_api::InputFile> &sticker,
+                                            Promise<Unit> &&promise) {
+  auto input_user = td_->contacts_manager_->get_input_user(user_id);
+  if (input_user == nullptr) {
+    promise.set_error(Status::Error(3, "User not found"));
+    return FileId();
+  }
+  DialogId dialog_id(user_id);
+  auto input_peer = td_->messages_manager_->get_input_peer(dialog_id, AccessRights::Write);
+  if (input_peer == nullptr) {
+    promise.set_error(Status::Error(3, "Have no access to the user"));
+    return FileId();
+  }
+
+  auto r_file_id = prepare_input_file(sticker);
+  if (r_file_id.is_error()) {
+    promise.set_error(r_file_id.move_as_error());
+    return FileId();
+  }
+  auto file_id = std::get<0>(r_file_id.ok());
+  auto is_url = std::get<1>(r_file_id.ok());
+  auto is_local = std::get<2>(r_file_id.ok());
+
+  if (is_url) {
+    do_upload_sticker_file(user_id, file_id, nullptr, std::move(promise));
+  } else if (is_local) {
+    upload_sticker_file(user_id, file_id, std::move(promise));
+  } else {
+    promise.set_value(Unit());
+  }
+
+  return file_id;
+}
+
+tl_object_ptr<telegram_api::inputStickerSetItem> StickersManager::get_input_sticker(td_api::inputSticker *sticker,
+                                                                                    FileId file_id) const {
+  FileView file_view = td_->file_manager_->get_file_view(file_id);
+  CHECK(file_view.has_remote_location());
+  auto input_document = file_view.remote_location().as_input_document();
+
+  tl_object_ptr<telegram_api::maskCoords> mask_coords;
+  if (sticker->mask_position_ != nullptr && sticker->mask_position_->point_ != nullptr) {
+    auto point = [mask_point = std::move(sticker->mask_position_->point_)]() {
+      switch (mask_point->get_id()) {
+        case td_api::maskPointForehead::ID:
+          return 0;
+        case td_api::maskPointEyes::ID:
+          return 1;
+        case td_api::maskPointMouth::ID:
+          return 2;
+        case td_api::maskPointChin::ID:
+          return 3;
+        default:
+          UNREACHABLE();
+          return -1;
+      }
+    }();
+    mask_coords = make_tl_object<telegram_api::maskCoords>(
+        point, sticker->mask_position_->x_shift_, sticker->mask_position_->y_shift_, sticker->mask_position_->scale_);
+  }
+
+  int32 flags = 0;
+  if (mask_coords != nullptr) {
+    flags |= telegram_api::inputStickerSetItem::MASK_COORDS_MASK;
+  }
+
+  return make_tl_object<telegram_api::inputStickerSetItem>(flags, std::move(input_document), sticker->emojis_,
+                                                           std::move(mask_coords));
+}
+
+void StickersManager::create_new_sticker_set(UserId user_id, string &title, string &short_name, bool is_masks,
+                                             vector<tl_object_ptr<td_api::inputSticker>> &&stickers,
+                                             Promise<Unit> &&promise) {
+  auto input_user = td_->contacts_manager_->get_input_user(user_id);
+  if (input_user == nullptr) {
+    return promise.set_error(Status::Error(3, "User not found"));
+  }
+  DialogId dialog_id(user_id);
+  auto input_peer = td_->messages_manager_->get_input_peer(dialog_id, AccessRights::Write);
+  if (input_peer == nullptr) {
+    return promise.set_error(Status::Error(3, "Have no access to the user"));
+  }
+
+  title = strip_empty_characters(title, MAX_STICKER_SET_TITLE_LENGTH);
+  if (title.empty()) {
+    return promise.set_error(Status::Error(3, "Sticker set title can't be empty"));
+  }
+
+  short_name = strip_empty_characters(short_name, MAX_STICKER_SET_SHORT_NAME_LENGTH);
+  if (short_name.empty()) {
+    return promise.set_error(Status::Error(3, "Sticker set name can't be empty"));
+  }
+
+  vector<FileId> file_ids;
+  file_ids.reserve(stickers.size());
+  vector<FileId> local_file_ids;
+  vector<FileId> url_file_ids;
+  for (auto &sticker : stickers) {
+    auto r_file_id = prepare_input_sticker(sticker.get());
+    if (r_file_id.is_error()) {
+      return promise.set_error(r_file_id.move_as_error());
+    }
+    auto file_id = std::get<0>(r_file_id.ok());
+    auto is_url = std::get<1>(r_file_id.ok());
+    auto is_local = std::get<2>(r_file_id.ok());
+
+    file_ids.push_back(file_id);
+    if (is_url) {
+      url_file_ids.push_back(file_id);
+    } else if (is_local) {
+      local_file_ids.push_back(file_id);
+    }
+  }
+
+  auto pending_new_sticker_set = make_unique<PendingNewStickerSet>();
+  pending_new_sticker_set->user_id = user_id;
+  pending_new_sticker_set->title = std::move(title);
+  pending_new_sticker_set->short_name = short_name;
+  pending_new_sticker_set->is_masks = is_masks;
+  pending_new_sticker_set->file_ids = std::move(file_ids);
+  pending_new_sticker_set->stickers = std::move(stickers);
+  pending_new_sticker_set->promise = std::move(promise);
+
+  auto &multipromise = pending_new_sticker_set->upload_files_multipromise;
+
+  int64 random_id;
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 || pending_new_sticker_sets_.find(random_id) != pending_new_sticker_sets_.end());
+  pending_new_sticker_sets_[random_id] = std::move(pending_new_sticker_set);
+
+  multipromise.add_promise(PromiseCreator::lambda([random_id](Result<Unit> result) {
+    send_closure_later(G()->stickers_manager(), &StickersManager::on_new_stickers_uploaded, random_id,
+                       std::move(result));
+  }));
+  auto lock_promise = multipromise.get_promise();
+
+  for (auto file_id : url_file_ids) {
+    do_upload_sticker_file(user_id, file_id, nullptr, multipromise.get_promise());
+  }
+
+  for (auto file_id : local_file_ids) {
+    upload_sticker_file(user_id, file_id, multipromise.get_promise());
+  }
+
+  lock_promise.set_value(Unit());
+}
+
+void StickersManager::upload_sticker_file(UserId user_id, FileId file_id, Promise<Unit> &&promise) {
+  CHECK(td_->documents_manager_->get_input_media(file_id, nullptr, nullptr) == nullptr);
+
+  auto upload_file_id = td_->documents_manager_->dup_document(td_->file_manager_->dup_file_id(file_id), file_id);
+
+  being_uploaded_files_[upload_file_id] = {user_id, std::move(promise)};
+  LOG(INFO) << "Ask to upload sticker file " << upload_file_id;
+  td_->file_manager_->upload(upload_file_id, upload_sticker_file_callback_, 2, 0);
+}
+
+void StickersManager::on_upload_sticker_file(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) {
+  LOG(INFO) << "Sticker file " << file_id << " has been uploaded";
+
+  auto it = being_uploaded_files_.find(file_id);
+  CHECK(it != being_uploaded_files_.end());
+
+  auto user_id = it->second.first;
+  auto promise = std::move(it->second.second);
+
+  being_uploaded_files_.erase(it);
+
+  do_upload_sticker_file(user_id, file_id, std::move(input_file), std::move(promise));
+}
+
+void StickersManager::on_upload_sticker_file_error(FileId file_id, Status status) {
+  if (G()->close_flag()) {
+    // do not fail upload if closing
+    return;
+  }
+
+  LOG(WARNING) << "Sticker file " << file_id << " has upload error " << status;
+  CHECK(status.is_error());
+
+  auto it = being_uploaded_files_.find(file_id);
+  CHECK(it != being_uploaded_files_.end());
+
+  auto promise = std::move(it->second.second);
+
+  being_uploaded_files_.erase(it);
+
+  // TODO FILE_PART_X_MISSING support
+
+  promise.set_error(Status::Error(status.code() > 0 ? status.code() : 500,
+                                  status.message()));  // TODO CHECK that status has always a code
+}
+
+void StickersManager::do_upload_sticker_file(UserId user_id, FileId file_id,
+                                             tl_object_ptr<telegram_api::InputFile> &&input_file,
+                                             Promise<Unit> &&promise) {
+  DialogId dialog_id(user_id);
+  auto input_peer = td_->messages_manager_->get_input_peer(dialog_id, AccessRights::Write);
+  if (input_peer == nullptr) {
+    return promise.set_error(Status::Error(3, "Have no access to the user"));
+  }
+
+  auto input_media = td_->documents_manager_->get_input_media(file_id, std::move(input_file), nullptr);
+  CHECK(input_media != nullptr);
+
+  td_->create_handler<UploadStickerFileQuery>(std::move(promise))
+      ->send(std::move(input_peer), file_id, std::move(input_media));
+}
+
+void StickersManager::on_uploaded_sticker_file(FileId file_id, tl_object_ptr<telegram_api::MessageMedia> media,
+                                               Promise<Unit> &&promise) {
+  CHECK(media != nullptr);
+  if (media->get_id() != telegram_api::messageMediaDocument::ID) {
+    return promise.set_error(Status::Error(400, "Can't upload sticker file: wrong file type"));
+  }
+
+  auto message_document = move_tl_object_as<telegram_api::messageMediaDocument>(media);
+  auto document_ptr = std::move(message_document->document_);
+  int32 document_id = document_ptr->get_id();
+  if (document_id == telegram_api::documentEmpty::ID) {
+    return promise.set_error(Status::Error(400, "Can't upload sticker file: empty file"));
+  }
+  CHECK(document_id == telegram_api::document::ID);
+
+  auto parsed_document = td_->documents_manager_->on_get_document(
+      move_tl_object_as<telegram_api::document>(document_ptr), DialogId(), nullptr);
+  if (parsed_document.first != DocumentsManager::DocumentType::General) {
+    return promise.set_error(Status::Error(400, "Wrong file type"));
+  }
+
+  td_->documents_manager_->merge_documents(parsed_document.second, file_id, true);
+  promise.set_value(Unit());
+}
+
+void StickersManager::on_new_stickers_uploaded(int64 random_id, Result<Unit> result) {
+  auto it = pending_new_sticker_sets_.find(random_id);
+  CHECK(it != pending_new_sticker_sets_.end());
+
+  auto pending_new_sticker_set = std::move(it->second);
+  CHECK(pending_new_sticker_set != nullptr);
+
+  pending_new_sticker_sets_.erase(it);
+
+  if (result.is_error()) {
+    pending_new_sticker_set->promise.set_error(result.move_as_error());
+    return;
+  }
+
+  CHECK(pending_new_sticker_set->upload_files_multipromise.promise_count() == 0);
+
+  auto input_user = td_->contacts_manager_->get_input_user(pending_new_sticker_set->user_id);
+  if (input_user == nullptr) {
+    return pending_new_sticker_set->promise.set_error(Status::Error(3, "User not found"));
+  }
+
+  bool is_masks = pending_new_sticker_set->is_masks;
+
+  auto sticker_count = pending_new_sticker_set->stickers.size();
+  vector<tl_object_ptr<telegram_api::inputStickerSetItem>> input_stickers;
+  input_stickers.reserve(sticker_count);
+  for (size_t i = 0; i < sticker_count; i++) {
+    input_stickers.push_back(
+        get_input_sticker(pending_new_sticker_set->stickers[i].get(), pending_new_sticker_set->file_ids[i]));
+  }
+
+  td_->create_handler<CreateNewStickerSetQuery>(std::move(pending_new_sticker_set->promise))
+      ->send(std::move(input_user), pending_new_sticker_set->title, pending_new_sticker_set->short_name, is_masks,
+             std::move(input_stickers));
+}
+
+void StickersManager::add_sticker_to_set(UserId user_id, string &short_name,
+                                         tl_object_ptr<td_api::inputSticker> &&sticker, Promise<Unit> &&promise) {
+  auto input_user = td_->contacts_manager_->get_input_user(user_id);
+  if (input_user == nullptr) {
+    return promise.set_error(Status::Error(3, "User not found"));
+  }
+  DialogId dialog_id(user_id);
+  auto input_peer = td_->messages_manager_->get_input_peer(dialog_id, AccessRights::Write);
+  if (input_peer == nullptr) {
+    return promise.set_error(Status::Error(3, "Have no access to the user"));
+  }
+
+  short_name = strip_empty_characters(short_name, MAX_STICKER_SET_SHORT_NAME_LENGTH);
+  if (short_name.empty()) {
+    return promise.set_error(Status::Error(3, "Sticker set name can't be empty"));
+  }
+
+  auto r_file_id = prepare_input_sticker(sticker.get());
+  if (r_file_id.is_error()) {
+    return promise.set_error(r_file_id.move_as_error());
+  }
+  auto file_id = std::get<0>(r_file_id.ok());
+  auto is_url = std::get<1>(r_file_id.ok());
+  auto is_local = std::get<2>(r_file_id.ok());
+
+  auto pending_add_sticker_to_set = make_unique<PendingAddStickerToSet>();
+  pending_add_sticker_to_set->short_name = short_name;
+  pending_add_sticker_to_set->file_id = file_id;
+  pending_add_sticker_to_set->sticker = std::move(sticker);
+  pending_add_sticker_to_set->promise = std::move(promise);
+
+  int64 random_id;
+  do {
+    random_id = Random::secure_int64();
+  } while (random_id == 0 || pending_add_sticker_to_sets_.find(random_id) != pending_add_sticker_to_sets_.end());
+  pending_add_sticker_to_sets_[random_id] = std::move(pending_add_sticker_to_set);
+
+  auto on_upload_promise = PromiseCreator::lambda([random_id](Result<Unit> result) {
+    send_closure(G()->stickers_manager(), &StickersManager::on_added_sticker_uploaded, random_id, std::move(result));
+  });
+
+  if (is_url) {
+    do_upload_sticker_file(user_id, file_id, nullptr, std::move(on_upload_promise));
+  } else if (is_local) {
+    upload_sticker_file(user_id, file_id, std::move(on_upload_promise));
+  } else {
+    on_upload_promise.set_value(Unit());
+  }
+}
+
+void StickersManager::on_added_sticker_uploaded(int64 random_id, Result<Unit> result) {
+  auto it = pending_add_sticker_to_sets_.find(random_id);
+  CHECK(it != pending_add_sticker_to_sets_.end());
+
+  auto pending_add_sticker_to_set = std::move(it->second);
+  CHECK(pending_add_sticker_to_set != nullptr);
+
+  pending_add_sticker_to_sets_.erase(it);
+
+  if (result.is_error()) {
+    pending_add_sticker_to_set->promise.set_error(result.move_as_error());
+    return;
+  }
+
+  td_->create_handler<AddStickerToSetQuery>(std::move(pending_add_sticker_to_set->promise))
+      ->send(pending_add_sticker_to_set->short_name,
+             get_input_sticker(pending_add_sticker_to_set->sticker.get(), pending_add_sticker_to_set->file_id));
+}
+
+void StickersManager::set_sticker_position_in_set(const tl_object_ptr<td_api::InputFile> &sticker, int32 position,
+                                                  Promise<Unit> &&promise) {
+  if (position < 0) {
+    return promise.set_error(Status::Error(7, "Wrong sticker position specified"));
+  }
+
+  auto r_file_id = td_->file_manager_->get_input_file_id(FileType::Sticker, sticker, DialogId(), false, false);
+  if (r_file_id.is_error()) {
+    return promise.set_error(Status::Error(7, r_file_id.error().message()));  // TODO do not drop error code
+  }
+
+  auto file_id = r_file_id.move_as_ok();
+  auto file_view = td_->file_manager_->get_file_view(file_id);
+  if (!file_view.has_remote_location() || file_view.remote_location().is_encrypted() ||
+      file_view.remote_location().is_web()) {
+    return promise.set_error(Status::Error(7, "Wrong sticker file specified"));
+  }
+
+  td_->create_handler<SetStickerPositionQuery>(std::move(promise))
+      ->send(file_view.remote_location().as_input_document(), position);
+}
+
+void StickersManager::remove_sticker_from_set(const tl_object_ptr<td_api::InputFile> &sticker,
+                                              Promise<Unit> &&promise) {
+  auto r_file_id = td_->file_manager_->get_input_file_id(FileType::Sticker, sticker, DialogId(), false, false);
+  if (r_file_id.is_error()) {
+    return promise.set_error(Status::Error(7, r_file_id.error().message()));  // TODO do not drop error code
+  }
+
+  auto file_id = r_file_id.move_as_ok();
+  auto file_view = td_->file_manager_->get_file_view(file_id);
+  if (!file_view.has_remote_location() || file_view.remote_location().is_encrypted() ||
+      file_view.remote_location().is_web()) {
+    return promise.set_error(Status::Error(7, "Wrong sticker file specified"));
+  }
+
+  td_->create_handler<DeleteStickerFromSetQuery>(std::move(promise))
+      ->send(file_view.remote_location().as_input_document());
+}
+
+vector<FileId> StickersManager::get_attached_sticker_file_ids(const vector<int32> &int_file_ids) {
+  vector<FileId> result;
+
+  result.reserve(int_file_ids.size());
+  for (auto int_file_id : int_file_ids) {
+    FileId file_id(int_file_id, 0);
+    if (get_sticker(file_id) == nullptr) {
+      LOG(WARNING) << "Can't find sticker " << file_id;
+      continue;
+    }
+    auto file_view = td_->file_manager_->get_file_view(file_id);
+    CHECK(!file_view.empty());
+    if (!file_view.has_remote_location()) {
+      LOG(WARNING) << "Sticker " << file_id << " has no remote location";
+      continue;
+    }
+    if (file_view.remote_location().is_encrypted()) {
+      LOG(WARNING) << "Sticker " << file_id << " is encrypted";
+      continue;
+    }
+    if (file_view.remote_location().is_web()) {
+      LOG(WARNING) << "Sticker " << file_id << " is web";
+      continue;
+    }
+    result.push_back(file_id);
+
+    if (!td_->auth_manager_->is_bot()) {
+      add_recent_sticker_by_id(true, file_id);
+    }
+  }
+
+  return result;
+}
+
+int32 StickersManager::get_sticker_sets_hash(const vector<int64> &sticker_set_ids) const {
+  vector<uint32> numbers;
+  numbers.reserve(sticker_set_ids.size());
+  for (auto sticker_set_id : sticker_set_ids) {
+    const StickerSet *sticker_set = get_sticker_set(sticker_set_id);
+    CHECK(sticker_set != nullptr);
+    CHECK(sticker_set->is_inited);
+    numbers.push_back(static_cast<uint32>(sticker_set->hash));
+  }
+  return get_vector_hash(numbers);
+}
+
+int32 StickersManager::get_featured_sticker_sets_hash() const {
+  vector<uint32> numbers;
+  numbers.reserve(featured_sticker_set_ids_.size());
+  for (auto sticker_set_id : featured_sticker_set_ids_) {
+    const StickerSet *sticker_set = get_sticker_set(sticker_set_id);
+    CHECK(sticker_set != nullptr);
+    CHECK(sticker_set->is_inited);
+
+    uint64 pack_id = static_cast<uint64>(sticker_set_id);
+    numbers.push_back(static_cast<uint32>(pack_id >> 32));
+    numbers.push_back(static_cast<uint32>(pack_id & 0xFFFFFFFF));
+
+    if (!sticker_set->is_viewed) {
+      numbers.push_back(1);
+    }
+  }
+  return get_vector_hash(numbers);
+}
+
+void StickersManager::send_update_installed_sticker_sets(bool from_database) {
+  for (int is_masks = 0; is_masks < 2; is_masks++) {
+    if (need_update_installed_sticker_sets_[is_masks]) {
+      need_update_installed_sticker_sets_[is_masks] = false;
+      if (are_installed_sticker_sets_loaded_[is_masks]) {
+        installed_sticker_sets_hash_[is_masks] = get_sticker_sets_hash(installed_sticker_set_ids_[is_masks]);
+        send_closure(G()->td(), &Td::send_update,
+                     make_tl_object<td_api::updateInstalledStickerSets>(
+                         is_masks != 0, vector<int64>(installed_sticker_set_ids_[is_masks])));
+
+        if (G()->parameters().use_file_db && !from_database) {
+          LOG(INFO) << "Save installed " << (is_masks ? "mask " : "") << "sticker sets to database";
+          StickerSetListLogEvent log_event(installed_sticker_set_ids_[is_masks]);
+          G()->td_db()->get_sqlite_pmc()->set(is_masks ? "sss1" : "sss0", log_event_store(log_event).as_slice().str(),
+                                              Auto());
+        }
+      }
+    }
+  }
+}
+
+void StickersManager::send_update_featured_sticker_sets() {
+  if (need_update_featured_sticker_sets_) {
+    need_update_featured_sticker_sets_ = false;
+    featured_sticker_sets_hash_ = get_featured_sticker_sets_hash();
+
+    send_closure(
+        G()->td(), &Td::send_update,
+        make_tl_object<td_api::updateTrendingStickerSets>(get_sticker_sets_object(-1, featured_sticker_set_ids_, 5)));
+  }
+}
+
+void StickersManager::reload_recent_stickers(bool is_attached, bool force) {
+  auto &next_load_time = next_recent_stickers_load_time_[is_attached];
+  if (!td_->auth_manager_->is_bot() && next_load_time >= 0 && (next_load_time < Time::now() || force)) {
+    LOG_IF(INFO, force) << "Reload recent stickers";
+    next_load_time = -1;
+    td_->create_handler<GetRecentStickersQuery>()->send(is_attached, recent_stickers_hash_[is_attached]);
+  }
+}
+
+vector<FileId> StickersManager::get_recent_stickers(bool is_attached, Promise<Unit> &&promise) {
+  if (!are_recent_stickers_loaded_[is_attached]) {
+    load_recent_stickers(is_attached, std::move(promise));
+    return {};
+  }
+  reload_recent_stickers(is_attached, false);
+
+  promise.set_value(Unit());
+  return recent_sticker_ids_[is_attached];
+}
+
+void StickersManager::load_recent_stickers(bool is_attached, Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    are_recent_stickers_loaded_[is_attached] = true;
+  }
+  if (are_recent_stickers_loaded_[is_attached]) {
+    promise.set_value(Unit());
+    return;
+  }
+  load_recent_stickers_queries_[is_attached].push_back(std::move(promise));
+  if (load_recent_stickers_queries_[is_attached].size() == 1u) {
+    if (G()->parameters().use_file_db) {
+      LOG(INFO) << "Trying to load recent " << (is_attached ? "attached " : "") << "stickers from database";
+      G()->td_db()->get_sqlite_pmc()->get(
+          is_attached ? "ssr1" : "ssr0", PromiseCreator::lambda([is_attached](string value) {
+            send_closure(G()->stickers_manager(), &StickersManager::on_load_recent_stickers_from_database, is_attached,
+                         std::move(value));
+          }));
+    } else {
+      LOG(INFO) << "Trying to load recent " << (is_attached ? "attached " : "") << "stickers from server";
+      reload_recent_stickers(is_attached, true);
+    }
+  }
+}
+
+void StickersManager::on_load_recent_stickers_from_database(bool is_attached, string value) {
+  if (value.empty()) {
+    LOG(INFO) << "Recent " << (is_attached ? "attached " : "") << "stickers aren't found in database";
+    reload_recent_stickers(is_attached, true);
+    return;
+  }
+
+  LOG(INFO) << "Successfully loaded recent " << (is_attached ? "attached " : "") << "stickers list of size "
+            << value.size() << " from database";
+
+  StickerListLogEvent log_event;
+  log_event_parse(log_event, value).ensure();
+
+  on_load_recent_stickers_finished(is_attached, std::move(log_event.sticker_ids), true);
+}
+
+void StickersManager::on_load_recent_stickers_finished(bool is_attached, vector<FileId> &&recent_sticker_ids,
+                                                       bool from_database) {
+  if (static_cast<int32>(recent_sticker_ids.size()) > recent_stickers_limit_) {
+    recent_sticker_ids.resize(recent_stickers_limit_);
+  }
+  recent_sticker_ids_[is_attached] = std::move(recent_sticker_ids);
+  are_recent_stickers_loaded_[is_attached] = true;
+  need_update_recent_stickers_[is_attached] = true;
+  send_update_recent_stickers(from_database);
+  auto promises = std::move(load_recent_stickers_queries_[is_attached]);
+  load_recent_stickers_queries_[is_attached].clear();
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+void StickersManager::on_get_recent_stickers(bool is_attached,
+                                             tl_object_ptr<telegram_api::messages_RecentStickers> &&stickers_ptr) {
+  CHECK(!td_->auth_manager_->is_bot());
+  next_recent_stickers_load_time_[is_attached] = Time::now_cached() + Random::fast(30 * 60, 50 * 60);
+
+  CHECK(stickers_ptr != nullptr);
+  int32 constructor_id = stickers_ptr->get_id();
+  if (constructor_id == telegram_api::messages_recentStickersNotModified::ID) {
+    LOG(INFO) << (is_attached ? "Attached r" : "r") << "ecent stickers are not modified";
+    return;
+  }
+  CHECK(constructor_id == telegram_api::messages_recentStickers::ID);
+  auto stickers = move_tl_object_as<telegram_api::messages_recentStickers>(stickers_ptr);
+
+  vector<FileId> recent_sticker_ids;
+  recent_sticker_ids.reserve(stickers->stickers_.size());
+  for (auto &document_ptr : stickers->stickers_) {
+    auto sticker_id = on_get_sticker_document(std::move(document_ptr), true).second;
+    if (!sticker_id.is_valid()) {
+      continue;
+    }
+    recent_sticker_ids.push_back(sticker_id);
+  }
+
+  on_load_recent_stickers_finished(is_attached, std::move(recent_sticker_ids));
+
+  LOG_IF(ERROR, recent_stickers_hash_[is_attached] != stickers->hash_) << "Stickers hash mismatch";
+}
+
+void StickersManager::on_get_recent_stickers_failed(bool is_attached, Status error) {
+  CHECK(error.is_error());
+  next_recent_stickers_load_time_[is_attached] = Time::now_cached() + Random::fast(5, 10);
+  auto promises = std::move(load_recent_stickers_queries_[is_attached]);
+  load_recent_stickers_queries_[is_attached].clear();
+  for (auto &promise : promises) {
+    promise.set_error(error.clone());
+  }
+}
+
+int32 StickersManager::get_recent_stickers_hash(const vector<FileId> &sticker_ids) const {
+  vector<uint32> numbers;
+  numbers.reserve(sticker_ids.size() * 2);
+  for (auto sticker_id : sticker_ids) {
+    auto sticker = get_sticker(sticker_id);
+    CHECK(sticker != nullptr);
+    auto file_view = td_->file_manager_->get_file_view(sticker_id);
+    CHECK(file_view.has_remote_location());
+    CHECK(!file_view.remote_location().is_encrypted());
+    CHECK(!file_view.remote_location().is_web());
+    auto id = static_cast<uint64>(file_view.remote_location().get_id());
+    numbers.push_back(static_cast<uint32>(id >> 32));
+    numbers.push_back(static_cast<uint32>(id & 0xFFFFFFFF));
+  }
+  return get_vector_hash(numbers);
+}
+
+void StickersManager::add_recent_sticker(bool is_attached, const tl_object_ptr<td_api::InputFile> &input_file,
+                                         Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(7, "Method is not available for bots"));
+  }
+  if (!are_recent_stickers_loaded_[is_attached]) {
+    load_recent_stickers(is_attached, std::move(promise));
+    return;
+  }
+
+  auto r_file_id = td_->file_manager_->get_input_file_id(FileType::Sticker, input_file, DialogId(), false, false);
+  if (r_file_id.is_error()) {
+    return promise.set_error(Status::Error(7, r_file_id.error().message()));  // TODO do not drop error code
+  }
+
+  add_recent_sticker_inner(is_attached, r_file_id.ok(), std::move(promise));
+}
+
+void StickersManager::add_recent_sticker_inner(bool is_attached, FileId sticker_id, Promise<Unit> &&promise) {
+  if (add_recent_sticker_impl(is_attached, sticker_id, promise)) {
+    // TODO invokeAfter and log event
+    auto file_view = td_->file_manager_->get_file_view(sticker_id);
+    td_->create_handler<SaveRecentStickerQuery>(std::move(promise))
+        ->send(is_attached, file_view.remote_location().as_input_document(), false);
+  }
+}
+
+void StickersManager::add_recent_sticker_by_id(bool is_attached, FileId sticker_id) {
+  // TODO log event
+  Promise<Unit> promise;
+  add_recent_sticker_impl(is_attached, sticker_id, promise);
+}
+
+bool StickersManager::add_recent_sticker_impl(bool is_attached, FileId sticker_id, Promise<Unit> &promise) {
+  CHECK(!td_->auth_manager_->is_bot());
+
+  if (!are_recent_stickers_loaded_[is_attached]) {
+    load_recent_stickers(is_attached, PromiseCreator::lambda([is_attached, sticker_id,
+                                                              promise = std::move(promise)](Result<> result) mutable {
+                           if (result.is_ok()) {
+                             send_closure(G()->stickers_manager(), &StickersManager::add_recent_sticker_inner,
+                                          is_attached, sticker_id, std::move(promise));
+                           } else {
+                             promise.set_error(result.move_as_error());
+                           }
+                         }));
+    return false;
+  }
+
+  vector<FileId> &sticker_ids = recent_sticker_ids_[is_attached];
+  if (!sticker_ids.empty() && sticker_ids[0] == sticker_id) {
+    if (sticker_ids[0].get_remote() == 0 && sticker_id.get_remote() != 0) {
+      sticker_ids[0] = sticker_id;
+      save_recent_stickers_to_database(is_attached);
+    }
+
+    promise.set_value(Unit());
+    return false;
+  }
+
+  auto sticker = get_sticker(sticker_id);
+  if (sticker == nullptr) {
+    promise.set_error(Status::Error(7, "Sticker not found"));
+    return false;
+  }
+  if (sticker->set_id == 0) {
+    promise.set_error(Status::Error(7, "Stickers without sticker set can't be added to recent"));
+    return false;
+  }
+
+  auto file_view = td_->file_manager_->get_file_view(sticker_id);
+  if (!file_view.has_remote_location()) {
+    promise.set_error(Status::Error(7, "Can save only sent stickers"));
+    return false;
+  }
+  if (file_view.remote_location().is_encrypted()) {
+    promise.set_error(Status::Error(7, "Can't save encrypted stickers"));
+    return false;
+  }
+  if (file_view.remote_location().is_web()) {
+    promise.set_error(Status::Error(7, "Can't save web stickers"));
+    return false;
+  }
+
+  need_update_recent_stickers_[is_attached] = true;
+
+  auto it = std::find(sticker_ids.begin(), sticker_ids.end(), sticker_id);
+  if (it == sticker_ids.end()) {
+    if (static_cast<int32>(sticker_ids.size()) == recent_stickers_limit_) {
+      sticker_ids.back() = sticker_id;
+    } else {
+      sticker_ids.push_back(sticker_id);
+    }
+    it = sticker_ids.end() - 1;
+  }
+  std::rotate(sticker_ids.begin(), it, it + 1);
+  if (sticker_ids[0].get_remote() == 0 && sticker_id.get_remote() != 0) {
+    sticker_ids[0] = sticker_id;
+  }
+
+  send_update_recent_stickers();
+  return true;
+}
+
+void StickersManager::remove_recent_sticker(bool is_attached, const tl_object_ptr<td_api::InputFile> &input_file,
+                                            Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(7, "Method is not available for bots"));
+  }
+  if (!are_recent_stickers_loaded_[is_attached]) {
+    load_recent_stickers(is_attached, std::move(promise));
+    return;
+  }
+
+  auto r_file_id = td_->file_manager_->get_input_file_id(FileType::Sticker, input_file, DialogId(), false, false);
+  if (r_file_id.is_error()) {
+    return promise.set_error(Status::Error(7, r_file_id.error().message()));  // TODO do not drop error code
+  }
+
+  vector<FileId> &sticker_ids = recent_sticker_ids_[is_attached];
+  FileId file_id = r_file_id.ok();
+  auto it = std::find(sticker_ids.begin(), sticker_ids.end(), file_id);
+  if (it == sticker_ids.end()) {
+    return promise.set_value(Unit());
+  }
+
+  auto sticker = get_sticker(file_id);
+  if (sticker == nullptr) {
+    return promise.set_error(Status::Error(7, "Sticker not found"));
+  }
+
+  // TODO invokeAfter
+  auto file_view = td_->file_manager_->get_file_view(file_id);
+  CHECK(file_view.has_remote_location());
+  CHECK(!file_view.remote_location().is_encrypted());
+  CHECK(!file_view.remote_location().is_web());
+  td_->create_handler<SaveRecentStickerQuery>(std::move(promise))
+      ->send(is_attached, file_view.remote_location().as_input_document(), true);
+
+  sticker_ids.erase(it);
+
+  need_update_recent_stickers_[is_attached] = true;
+  send_update_recent_stickers();
+}
+
+void StickersManager::clear_recent_stickers(bool is_attached, Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(7, "Method is not available for bots"));
+  }
+  if (!are_recent_stickers_loaded_[is_attached]) {
+    load_recent_stickers(is_attached, std::move(promise));
+    return;
+  }
+
+  vector<FileId> &sticker_ids = recent_sticker_ids_[is_attached];
+  if (sticker_ids.empty()) {
+    return promise.set_value(Unit());
+  }
+
+  // TODO invokeAfter
+  td_->create_handler<ClearRecentStickersQuery>(std::move(promise))->send(is_attached);
+
+  sticker_ids.clear();
+
+  need_update_recent_stickers_[is_attached] = true;
+  send_update_recent_stickers();
+}
+
+void StickersManager::send_update_recent_stickers(bool from_database) {
+  for (int is_attached = 0; is_attached < 2; is_attached++) {
+    if (need_update_recent_stickers_[is_attached]) {
+      need_update_recent_stickers_[is_attached] = false;
+      if (are_recent_stickers_loaded_[is_attached]) {
+        recent_stickers_hash_[is_attached] = get_recent_stickers_hash(recent_sticker_ids_[is_attached]);
+        vector<int32> stickers;
+        stickers.reserve(recent_sticker_ids_[is_attached].size());
+        for (auto sticker_id : recent_sticker_ids_[is_attached]) {
+          stickers.push_back(sticker_id.get());
+        }
+        send_closure(G()->td(), &Td::send_update,
+                     make_tl_object<td_api::updateRecentStickers>(is_attached != 0, std::move(stickers)));
+
+        if (!from_database) {
+          save_recent_stickers_to_database(is_attached != 0);
+        }
+      }
+    }
+  }
+}
+
+void StickersManager::save_recent_stickers_to_database(bool is_attached) {
+  if (G()->parameters().use_file_db) {
+    LOG(INFO) << "Save recent " << (is_attached ? "attached " : "") << "stickers to database";
+    StickerListLogEvent log_event(recent_sticker_ids_[is_attached]);
+    G()->td_db()->get_sqlite_pmc()->set(is_attached ? "ssr1" : "ssr0", log_event_store(log_event).as_slice().str(),
+                                        Auto());
+  }
+}
+
+void StickersManager::on_update_recent_stickers_limit(int32 recent_stickers_limit) {
+  if (recent_stickers_limit != recent_stickers_limit_) {
+    if (recent_stickers_limit > 0) {
+      LOG(INFO) << "Update recent stickers limit to " << recent_stickers_limit;
+      recent_stickers_limit_ = recent_stickers_limit;
+      for (int is_attached = 0; is_attached < 2; is_attached++) {
+        if (static_cast<int32>(recent_sticker_ids_[is_attached].size()) > recent_stickers_limit) {
+          recent_sticker_ids_[is_attached].resize(recent_stickers_limit);
+          send_update_recent_stickers();
+        }
+      }
+    } else {
+      LOG(ERROR) << "Receive wrong recent stickers limit = " << recent_stickers_limit;
+    }
+  }
+}
+
+void StickersManager::on_update_favorite_stickers_limit(int32 favorite_stickers_limit) {
+  if (favorite_stickers_limit != favorite_stickers_limit_) {
+    if (favorite_stickers_limit > 0) {
+      LOG(INFO) << "Update favorite stickers limit to " << favorite_stickers_limit;
+      favorite_stickers_limit_ = favorite_stickers_limit;
+      if (static_cast<int32>(favorite_sticker_ids_.size()) > favorite_stickers_limit) {
+        favorite_sticker_ids_.resize(favorite_stickers_limit);
+        send_update_favorite_stickers();
+      }
+    } else {
+      LOG(ERROR) << "Receive wrong favorite stickers limit = " << favorite_stickers_limit;
+    }
+  }
+}
+
+void StickersManager::reload_favorite_stickers(bool force) {
+  if (!td_->auth_manager_->is_bot() && next_favorite_stickers_load_time_ >= 0 &&
+      (next_favorite_stickers_load_time_ < Time::now() || force)) {
+    LOG_IF(INFO, force) << "Reload favorite stickers";
+    next_favorite_stickers_load_time_ = -1;
+    td_->create_handler<GetFavedStickersQuery>()->send(get_favorite_stickers_hash());
+  }
+}
+
+vector<FileId> StickersManager::get_favorite_stickers(Promise<Unit> &&promise) {
+  if (!are_favorite_stickers_loaded_) {
+    load_favorite_stickers(std::move(promise));
+    return {};
+  }
+  reload_favorite_stickers(false);
+
+  promise.set_value(Unit());
+  return favorite_sticker_ids_;
+}
+
+void StickersManager::load_favorite_stickers(Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    are_favorite_stickers_loaded_ = true;
+  }
+  if (are_favorite_stickers_loaded_) {
+    promise.set_value(Unit());
+    return;
+  }
+  load_favorite_stickers_queries_.push_back(std::move(promise));
+  if (load_favorite_stickers_queries_.size() == 1u) {
+    if (G()->parameters().use_file_db) {
+      LOG(INFO) << "Trying to load favorite stickers from database";
+      G()->td_db()->get_sqlite_pmc()->get("ssfav", PromiseCreator::lambda([](string value) {
+                                            send_closure(G()->stickers_manager(),
+                                                         &StickersManager::on_load_favorite_stickers_from_database,
+                                                         std::move(value));
+                                          }));
+    } else {
+      LOG(INFO) << "Trying to load favorite stickers from server";
+      reload_favorite_stickers(true);
+    }
+  }
+}
+
+void StickersManager::on_load_favorite_stickers_from_database(const string &value) {
+  if (value.empty()) {
+    LOG(INFO) << "Favorite stickers aren't found in database";
+    reload_favorite_stickers(true);
+    return;
+  }
+
+  LOG(INFO) << "Successfully loaded favorite stickers list of size " << value.size() << " from database";
+
+  StickerListLogEvent log_event;
+  log_event_parse(log_event, value).ensure();
+
+  on_load_favorite_stickers_finished(std::move(log_event.sticker_ids), true);
+}
+
+void StickersManager::on_load_favorite_stickers_finished(vector<FileId> &&favorite_sticker_ids, bool from_database) {
+  if (static_cast<int32>(favorite_sticker_ids.size()) > favorite_stickers_limit_) {
+    favorite_sticker_ids.resize(favorite_stickers_limit_);
+  }
+  favorite_sticker_ids_ = std::move(favorite_sticker_ids);
+  are_favorite_stickers_loaded_ = true;
+  send_update_favorite_stickers(from_database);
+  auto promises = std::move(load_favorite_stickers_queries_);
+  load_favorite_stickers_queries_.clear();
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+void StickersManager::on_get_favorite_stickers(
+    tl_object_ptr<telegram_api::messages_FavedStickers> &&favorite_stickers_ptr) {
+  CHECK(!td_->auth_manager_->is_bot());
+  next_favorite_stickers_load_time_ = Time::now_cached() + Random::fast(30 * 60, 50 * 60);
+
+  CHECK(favorite_stickers_ptr != nullptr);
+  int32 constructor_id = favorite_stickers_ptr->get_id();
+  if (constructor_id == telegram_api::messages_favedStickersNotModified::ID) {
+    LOG(INFO) << "Favorite stickers are not modified";
+    return;
+  }
+  CHECK(constructor_id == telegram_api::messages_favedStickers::ID);
+  auto favorite_stickers = move_tl_object_as<telegram_api::messages_favedStickers>(favorite_stickers_ptr);
+
+  // TODO use favorite_stickers->packs_
+
+  vector<FileId> favorite_sticker_ids;
+  favorite_sticker_ids.reserve(favorite_stickers->stickers_.size());
+  for (auto &document_ptr : favorite_stickers->stickers_) {
+    auto sticker_id = on_get_sticker_document(std::move(document_ptr), true).second;
+    if (!sticker_id.is_valid()) {
+      continue;
+    }
+
+    favorite_sticker_ids.push_back(sticker_id);
+  }
+
+  on_load_favorite_stickers_finished(std::move(favorite_sticker_ids));
+
+  LOG_IF(ERROR, get_favorite_stickers_hash() != favorite_stickers->hash_) << "Favorite stickers hash mismatch";
+}
+
+void StickersManager::on_get_favorite_stickers_failed(Status error) {
+  CHECK(error.is_error());
+  next_favorite_stickers_load_time_ = Time::now_cached() + Random::fast(5, 10);
+  auto promises = std::move(load_favorite_stickers_queries_);
+  load_favorite_stickers_queries_.clear();
+  for (auto &promise : promises) {
+    promise.set_error(error.clone());
+  }
+}
+
+int32 StickersManager::get_favorite_stickers_hash() const {
+  return get_recent_stickers_hash(favorite_sticker_ids_);
+}
+
+void StickersManager::add_favorite_sticker(const tl_object_ptr<td_api::InputFile> &input_file,
+                                           Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(7, "Method is not available for bots"));
+  }
+  if (!are_favorite_stickers_loaded_) {
+    load_favorite_stickers(std::move(promise));
+    return;
+  }
+
+  auto r_file_id = td_->file_manager_->get_input_file_id(FileType::Sticker, input_file, DialogId(), false, false);
+  if (r_file_id.is_error()) {
+    return promise.set_error(Status::Error(7, r_file_id.error().message()));  // TODO do not drop error code
+  }
+
+  add_favorite_sticker_inner(r_file_id.ok(), std::move(promise));
+}
+
+void StickersManager::add_favorite_sticker_inner(FileId sticker_id, Promise<Unit> &&promise) {
+  if (add_favorite_sticker_impl(sticker_id, promise)) {
+    // TODO invokeAfter and log event
+    auto file_view = td_->file_manager_->get_file_view(sticker_id);
+    td_->create_handler<FaveStickerQuery>(std::move(promise))
+        ->send(file_view.remote_location().as_input_document(), false);
+  }
+}
+
+void StickersManager::add_favorite_sticker_by_id(FileId sticker_id) {
+  // TODO log event
+  Promise<Unit> promise;
+  add_favorite_sticker_impl(sticker_id, promise);
+}
+
+bool StickersManager::add_favorite_sticker_impl(FileId sticker_id, Promise<Unit> &promise) {
+  CHECK(!td_->auth_manager_->is_bot());
+
+  if (!are_favorite_stickers_loaded_) {
+    load_favorite_stickers(PromiseCreator::lambda([sticker_id, promise = std::move(promise)](Result<> result) mutable {
+      if (result.is_ok()) {
+        send_closure(G()->stickers_manager(), &StickersManager::add_favorite_sticker_inner, sticker_id,
+                     std::move(promise));
+      } else {
+        promise.set_error(result.move_as_error());
+      }
+    }));
+    return false;
+  }
+
+  if (!favorite_sticker_ids_.empty() && favorite_sticker_ids_[0] == sticker_id) {
+    if (favorite_sticker_ids_[0].get_remote() == 0 && sticker_id.get_remote() != 0) {
+      favorite_sticker_ids_[0] = sticker_id;
+      save_favorite_stickers_to_database();
+    }
+
+    promise.set_value(Unit());
+    return false;
+  }
+
+  auto sticker = get_sticker(sticker_id);
+  if (sticker == nullptr) {
+    promise.set_error(Status::Error(7, "Sticker not found"));
+    return false;
+  }
+  if (sticker->set_id == 0) {
+    promise.set_error(Status::Error(7, "Stickers without sticker set can't be favorite"));
+    return false;
+  }
+
+  auto file_view = td_->file_manager_->get_file_view(sticker_id);
+  if (!file_view.has_remote_location()) {
+    promise.set_error(Status::Error(7, "Can fave only sent stickers"));
+    return false;
+  }
+  if (file_view.remote_location().is_encrypted()) {
+    promise.set_error(Status::Error(7, "Can't fave encrypted stickers"));
+    return false;
+  }
+  if (file_view.remote_location().is_web()) {
+    promise.set_error(Status::Error(7, "Can't fave web stickers"));
+    return false;
+  }
+
+  auto it = std::find(favorite_sticker_ids_.begin(), favorite_sticker_ids_.end(), sticker_id);
+  if (it == favorite_sticker_ids_.end()) {
+    if (static_cast<int32>(favorite_sticker_ids_.size()) == favorite_stickers_limit_) {
+      favorite_sticker_ids_.back() = sticker_id;
+    } else {
+      favorite_sticker_ids_.push_back(sticker_id);
+    }
+    it = favorite_sticker_ids_.end() - 1;
+  }
+  std::rotate(favorite_sticker_ids_.begin(), it, it + 1);
+  if (favorite_sticker_ids_[0].get_remote() == 0 && sticker_id.get_remote() != 0) {
+    favorite_sticker_ids_[0] = sticker_id;
+  }
+
+  send_update_favorite_stickers();
+  return true;
+}
+
+void StickersManager::remove_favorite_sticker(const tl_object_ptr<td_api::InputFile> &input_file,
+                                              Promise<Unit> &&promise) {
+  if (td_->auth_manager_->is_bot()) {
+    return promise.set_error(Status::Error(7, "Method is not available for bots"));
+  }
+  if (!are_favorite_stickers_loaded_) {
+    load_favorite_stickers(std::move(promise));
+    return;
+  }
+
+  auto r_file_id = td_->file_manager_->get_input_file_id(FileType::Sticker, input_file, DialogId(), false, false);
+  if (r_file_id.is_error()) {
+    return promise.set_error(Status::Error(7, r_file_id.error().message()));  // TODO do not drop error code
+  }
+
+  FileId file_id = r_file_id.ok();
+  auto it = std::find(favorite_sticker_ids_.begin(), favorite_sticker_ids_.end(), file_id);
+  if (it == favorite_sticker_ids_.end()) {
+    return promise.set_value(Unit());
+  }
+
+  auto sticker = get_sticker(file_id);
+  if (sticker == nullptr) {
+    return promise.set_error(Status::Error(7, "Sticker not found"));
+  }
+
+  // TODO invokeAfter
+  auto file_view = td_->file_manager_->get_file_view(file_id);
+  CHECK(file_view.has_remote_location());
+  CHECK(!file_view.remote_location().is_encrypted());
+  CHECK(!file_view.remote_location().is_web());
+  td_->create_handler<FaveStickerQuery>(std::move(promise))
+      ->send(file_view.remote_location().as_input_document(), true);
+
+  favorite_sticker_ids_.erase(it);
+
+  send_update_favorite_stickers();
+}
+
+void StickersManager::send_update_favorite_stickers(bool from_database) {
+  if (are_favorite_stickers_loaded_) {
+    vector<int32> stickers;
+    stickers.reserve(favorite_sticker_ids_.size());
+    for (auto sticker_id : favorite_sticker_ids_) {
+      stickers.push_back(sticker_id.get());
+    }
+    send_closure(G()->td(), &Td::send_update, make_tl_object<td_api::updateFavoriteStickers>(std::move(stickers)));
+
+    if (!from_database) {
+      save_favorite_stickers_to_database();
+    }
+  }
+}
+
+void StickersManager::save_favorite_stickers_to_database() {
+  if (G()->parameters().use_file_db) {
+    LOG(INFO) << "Save favorite stickers to database";
+    StickerListLogEvent log_event(favorite_sticker_ids_);
+    G()->td_db()->get_sqlite_pmc()->set("ssfav", log_event_store(log_event).as_slice().str(), Auto());
+  }
+}
+
+vector<string> StickersManager::get_sticker_emojis(const tl_object_ptr<td_api::InputFile> &input_file,
+                                                   Promise<Unit> &&promise) {
+  auto r_file_id = td_->file_manager_->get_input_file_id(FileType::Sticker, input_file, DialogId(), false, false);
+  if (r_file_id.is_error()) {
+    promise.set_error(Status::Error(7, r_file_id.error().message()));  // TODO do not drop error code
+    return {};
+  }
+
+  FileId file_id = r_file_id.ok();
+
+  auto sticker = get_sticker(file_id);
+  if (sticker == nullptr) {
+    promise.set_value(Unit());
+    return {};
+  }
+  if (sticker->set_id == 0) {
+    promise.set_value(Unit());
+    return {};
+  }
+
+  auto file_view = td_->file_manager_->get_file_view(file_id);
+  if (!file_view.has_remote_location()) {
+    promise.set_value(Unit());
+    return {};
+  }
+  if (file_view.remote_location().is_encrypted()) {
+    promise.set_value(Unit());
+    return {};
+  }
+  if (file_view.remote_location().is_web()) {
+    promise.set_value(Unit());
+    return {};
+  }
+
+  const StickerSet *sticker_set = get_sticker_set(sticker->set_id);
+  if (update_sticker_set_cache(sticker_set, promise)) {
+    return {};
+  }
+
+  promise.set_value(Unit());
+  auto it = sticker_set->sticker_emojis_map_.find(file_id);
+  if (it == sticker_set->sticker_emojis_map_.end()) {
+    return {};
+  }
+
+  return it->second;
+}
+
+string StickersManager::remove_emoji_modifiers(string emoji) {
+  static Slice modifiers[] = {u8"\uFE0E" /* variation selector-15 */,
+                              u8"\uFE0F" /* variation selector-16 */,
+                              u8"\u200D\u2640" /* zero width joiner + female sign */,
+                              u8"\u200D\u2642" /* zero width joiner + male sign */,
+                              u8"\U0001F3FB" /* emoji modifier fitzpatrick type-1-2 */,
+                              u8"\U0001F3FC" /* emoji modifier fitzpatrick type-3 */,
+                              u8"\U0001F3FD" /* emoji modifier fitzpatrick type-4 */,
+                              u8"\U0001F3FE" /* emoji modifier fitzpatrick type-5 */,
+                              u8"\U0001F3FF" /* emoji modifier fitzpatrick type-6 */};
+  bool found = true;
+  while (found) {
+    found = false;
+    for (auto &modifier : modifiers) {
+      if (ends_with(emoji, modifier) && emoji.size() > modifier.size()) {
+        emoji.resize(emoji.size() - modifier.size());
+        found = true;
+      }
+    }
+  }
+  return emoji;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/StickersManager.h b/libs/tdlib/td/td/telegram/StickersManager.h
new file mode 100644
index 0000000000..367c8c5960
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/StickersManager.h
@@ -0,0 +1,508 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/MultiPromise.h"
+#include "td/actor/PromiseFuture.h"
+#include "td/actor/Timeout.h"
+
+#include "td/telegram/files/FileId.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/SecretInputMedia.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/Hints.h"
+#include "td/utils/Status.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include <memory>
+#include <tuple>
+#include <unordered_map>
+#include <unordered_set>
+#include <utility>
+
+namespace td {
+class MultiPromiseActor;
+class Td;
+}  // namespace td
+
+namespace td {
+
+class StickersManager : public Actor {
+ public:
+  StickersManager(Td *td, ActorShared<> parent);
+
+  tl_object_ptr<td_api::sticker> get_sticker_object(FileId file_id);
+
+  tl_object_ptr<td_api::stickers> get_stickers_object(const vector<FileId> &sticker_ids);
+
+  tl_object_ptr<td_api::stickerSet> get_sticker_set_object(int64 sticker_set_id);
+
+  tl_object_ptr<td_api::stickerSets> get_sticker_sets_object(int32 total_count, const vector<int64> &sticker_set_ids,
+                                                             size_t covers_limit);
+
+  tl_object_ptr<telegram_api::InputStickerSet> get_input_sticker_set(int64 sticker_set_id) const;
+
+  void create_sticker(FileId file_id, PhotoSize thumbnail, Dimensions dimensions, bool from_message,
+                      tl_object_ptr<telegram_api::documentAttributeSticker> sticker,
+                      MultiPromiseActor *load_data_multipromise_ptr);
+
+  bool has_input_media(FileId sticker_file_id, bool is_secret) const;
+
+  tl_object_ptr<telegram_api::InputMedia> get_input_media(FileId file_id,
+                                                          tl_object_ptr<telegram_api::InputFile> input_file,
+                                                          tl_object_ptr<telegram_api::InputFile> input_thumbnail) const;
+
+  SecretInputMedia get_secret_input_media(FileId sticker_file_id,
+                                          tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                          BufferSlice thumbnail) const;
+
+  vector<FileId> get_stickers(string emoji, int32 limit, bool force, Promise<Unit> &&promise);
+
+  vector<FileId> search_stickers(string emoji, int32 limit, Promise<Unit> &&promise);
+
+  vector<int64> get_installed_sticker_sets(bool is_masks, Promise<Unit> &&promise);
+
+  int64 add_sticker_set(tl_object_ptr<telegram_api::InputStickerSet> &&set_ptr);
+
+  int64 get_sticker_set(int64 set_id, Promise<Unit> &&promise);
+
+  int64 search_sticker_set(const string &short_name_to_search, Promise<Unit> &&promise);
+
+  std::pair<int32, vector<int64>> search_installed_sticker_sets(bool is_masks, const string &query, int32 limit,
+                                                                Promise<Unit> &&promise);
+
+  vector<int64> search_sticker_sets(const string &query, Promise<Unit> &&promise);
+
+  void change_sticker_set(int64 set_id, bool is_installed, bool is_archived, Promise<Unit> &&promise);
+
+  void view_featured_sticker_sets(const vector<int64> &sticker_set_ids);
+
+  void on_get_installed_sticker_sets(bool is_masks, tl_object_ptr<telegram_api::messages_AllStickers> &&stickers_ptr);
+
+  void on_get_installed_sticker_sets_failed(bool is_masks, Status error);
+
+  void on_get_messages_sticker_set(int64 sticker_set_id, tl_object_ptr<telegram_api::messages_stickerSet> &&set,
+                                   bool is_changed);
+
+  int64 on_get_sticker_set(tl_object_ptr<telegram_api::stickerSet> &&set, bool is_changed);
+
+  int64 on_get_sticker_set_covered(tl_object_ptr<telegram_api::StickerSetCovered> &&set_ptr, bool is_changed);
+
+  void on_load_sticker_set_fail(int64 sticker_set_id, const Status &error);
+
+  void on_install_sticker_set(int64 set_id, bool is_archived,
+                              tl_object_ptr<telegram_api::messages_StickerSetInstallResult> &&result);
+
+  void on_uninstall_sticker_set(int64 set_id);
+
+  void on_update_sticker_sets();
+
+  void on_update_sticker_sets_order(bool is_masks, const vector<int64> &sticker_set_ids);
+
+  std::pair<int32, vector<int64>> get_archived_sticker_sets(bool is_masks, int64 offset_sticker_set_id, int32 limit,
+                                                            bool force, Promise<Unit> &&promise);
+
+  void on_get_archived_sticker_sets(bool is_masks,
+                                    vector<tl_object_ptr<telegram_api::StickerSetCovered>> &&sticker_sets,
+                                    int32 total_count);
+
+  vector<int64> get_featured_sticker_sets(Promise<Unit> &&promise);
+
+  void on_get_featured_sticker_sets(tl_object_ptr<telegram_api::messages_FeaturedStickers> &&sticker_sets_ptr);
+
+  void on_get_featured_sticker_sets_failed(Status error);
+
+  vector<int64> get_attached_sticker_sets(FileId file_id, Promise<Unit> &&promise);
+
+  void on_get_attached_sticker_sets(FileId file_id,
+                                    vector<tl_object_ptr<telegram_api::StickerSetCovered>> &&sticker_sets);
+
+  void reorder_installed_sticker_sets(bool is_masks, const vector<int64> &sticker_set_ids, Promise<Unit> &&promise);
+
+  FileId upload_sticker_file(UserId user_id, const tl_object_ptr<td_api::InputFile> &sticker, Promise<Unit> &&promise);
+
+  void create_new_sticker_set(UserId user_id, string &title, string &short_name, bool is_masks,
+                              vector<tl_object_ptr<td_api::inputSticker>> &&stickers, Promise<Unit> &&promise);
+
+  void add_sticker_to_set(UserId user_id, string &short_name, tl_object_ptr<td_api::inputSticker> &&sticker,
+                          Promise<Unit> &&promise);
+
+  void set_sticker_position_in_set(const tl_object_ptr<td_api::InputFile> &sticker, int32 position,
+                                   Promise<Unit> &&promise);
+
+  void remove_sticker_from_set(const tl_object_ptr<td_api::InputFile> &sticker, Promise<Unit> &&promise);
+
+  vector<FileId> get_recent_stickers(bool is_attached, Promise<Unit> &&promise);
+
+  void on_get_recent_stickers(bool is_attached, tl_object_ptr<telegram_api::messages_RecentStickers> &&stickers_ptr);
+
+  void on_get_recent_stickers_failed(bool is_attached, Status error);
+
+  void add_recent_sticker(bool is_attached, const tl_object_ptr<td_api::InputFile> &input_file,
+                          Promise<Unit> &&promise);
+
+  void add_recent_sticker_by_id(bool is_attached, FileId sticker_id);
+
+  void remove_recent_sticker(bool is_attached, const tl_object_ptr<td_api::InputFile> &input_file,
+                             Promise<Unit> &&promise);
+
+  void clear_recent_stickers(bool is_attached, Promise<Unit> &&promise);
+
+  void on_update_recent_stickers_limit(int32 recent_stickers_limit);
+
+  void on_update_favorite_stickers_limit(int32 favorite_stickers_limit);
+
+  void reload_favorite_stickers(bool force);
+
+  void on_get_favorite_stickers(tl_object_ptr<telegram_api::messages_FavedStickers> &&favorite_stickers_ptr);
+
+  void on_get_favorite_stickers_failed(Status error);
+
+  vector<FileId> get_favorite_stickers(Promise<Unit> &&promise);
+
+  void add_favorite_sticker(const tl_object_ptr<td_api::InputFile> &input_file, Promise<Unit> &&promise);
+
+  void add_favorite_sticker_by_id(FileId sticker_id);
+
+  void remove_favorite_sticker(const tl_object_ptr<td_api::InputFile> &input_file, Promise<Unit> &&promise);
+
+  vector<FileId> get_attached_sticker_file_ids(const vector<int32> &int_file_ids);
+
+  vector<string> get_sticker_emojis(const tl_object_ptr<td_api::InputFile> &input_file, Promise<Unit> &&promise);
+
+  void reload_installed_sticker_sets(bool is_masks, bool force);
+
+  void reload_featured_sticker_sets(bool force);
+
+  void reload_recent_stickers(bool is_attached, bool force);
+
+  FileId get_sticker_thumbnail_file_id(FileId file_id) const;
+
+  void delete_sticker_thumbnail(FileId file_id);
+
+  FileId dup_sticker(FileId new_id, FileId old_id);
+
+  bool merge_stickers(FileId new_id, FileId old_id, bool can_delete_old);
+
+  template <class T>
+  void store_sticker(FileId file_id, bool in_sticker_set, T &storer) const;
+
+  template <class T>
+  FileId parse_sticker(bool in_sticker_set, T &parser);
+
+  void on_uploaded_sticker_file(FileId file_id, tl_object_ptr<telegram_api::MessageMedia> media,
+                                Promise<Unit> &&promise);
+
+  void on_find_stickers_success(const string &emoji, tl_object_ptr<telegram_api::messages_Stickers> &&sticker_sets);
+
+  void on_find_stickers_fail(const string &emoji, Status &&error);
+
+  void on_find_sticker_sets_success(const string &query,
+                                    tl_object_ptr<telegram_api::messages_FoundStickerSets> &&sticker_sets);
+
+  void on_find_sticker_sets_fail(const string &query, Status &&error);
+
+ private:
+  static constexpr int32 MAX_FEATURED_STICKER_SET_VIEW_DELAY = 5;
+
+  static constexpr int32 MAX_FOUND_STICKERS = 100;                 // server side limit
+  static constexpr int64 MAX_STICKER_FILE_SIZE = 1 << 19;          // server side limit
+  static constexpr size_t MAX_STICKER_SET_TITLE_LENGTH = 64;       // server side limit
+  static constexpr size_t MAX_STICKER_SET_SHORT_NAME_LENGTH = 64;  // server side limit
+
+  static constexpr int64 GREAT_MINDS_SET_ID = 1842540969984001;
+
+  class Sticker {
+   public:
+    int64 set_id = 0;
+    string alt;
+    Dimensions dimensions;
+    PhotoSize message_thumbnail;
+    PhotoSize sticker_thumbnail;
+    FileId file_id;
+    bool is_mask = false;
+    int32 point = -1;
+    double x_shift = 0;
+    double y_shift = 0;
+    double scale = 0;
+
+    bool is_changed = true;
+  };
+
+  class StickerSet {
+   public:
+    bool is_inited = false;
+    bool was_loaded = false;
+    bool is_loaded = false;
+
+    int64 id = 0;
+    int64 access_hash = 0;
+    string title;
+    string short_name;
+    int32 sticker_count = 0;
+    int32 hash = 0;
+    int32 expires_at = 0;
+
+    vector<FileId> sticker_ids;
+    std::unordered_map<string, vector<FileId>> emoji_stickers_map_;              // emoji -> stickers
+    std::unordered_map<FileId, vector<string>, FileIdHash> sticker_emojis_map_;  // sticker -> emojis
+
+    bool is_installed = false;
+    bool is_archived = false;
+    bool is_official = false;
+    bool is_masks = false;
+    bool is_viewed = true;
+    bool is_changed = true;
+
+    vector<uint32> load_requests;
+    vector<uint32> load_without_stickers_requests;
+  };
+
+  struct PendingNewStickerSet {
+    MultiPromiseActor upload_files_multipromise;
+    UserId user_id;
+    string title;
+    string short_name;
+    bool is_masks;
+    vector<FileId> file_ids;
+    vector<tl_object_ptr<td_api::inputSticker>> stickers;
+    Promise<> promise;
+  };
+
+  struct PendingAddStickerToSet {
+    string short_name;
+    FileId file_id;
+    tl_object_ptr<td_api::inputSticker> sticker;
+    Promise<> promise;
+  };
+
+  class StickerListLogEvent;
+  class StickerSetListLogEvent;
+
+  class UploadStickerFileCallback;
+
+  tl_object_ptr<td_api::MaskPoint> get_mask_point_object(int32 point);
+
+  tl_object_ptr<td_api::stickerSetInfo> get_sticker_set_info_object(int64 sticker_set_id, size_t covers_limit);
+
+  Sticker *get_sticker(FileId file_id);
+  const Sticker *get_sticker(FileId file_id) const;
+
+  FileId on_get_sticker(std::unique_ptr<Sticker> new_sticker, bool replace);
+
+  StickerSet *get_sticker_set(int64 sticker_set_id);
+  const StickerSet *get_sticker_set(int64 sticker_set_id) const;
+
+  StickerSet *add_sticker_set(int64 sticker_set_id, int64 access_hash);
+
+  std::pair<int64, FileId> on_get_sticker_document(tl_object_ptr<telegram_api::Document> &&document_ptr,
+                                                   bool from_message);
+
+  static tl_object_ptr<telegram_api::InputStickerSet> get_input_sticker_set(const StickerSet *set);
+
+  int64 on_get_input_sticker_set(FileId sticker_file_id, tl_object_ptr<telegram_api::InputStickerSet> &&set_ptr,
+                                 MultiPromiseActor *load_data_multipromise_ptr = nullptr);
+
+  void on_resolve_sticker_set_short_name(FileId sticker_file_id, const string &short_name);
+
+  int apply_installed_sticker_sets_order(bool is_masks, const vector<int64> &sticker_set_ids);
+
+  void on_update_sticker_set(StickerSet *sticker_set, bool is_installed, bool is_archived, bool is_changed,
+                             bool from_database = false);
+
+  static string get_sticker_set_database_key(int64 set_id);
+
+  static string get_full_sticker_set_database_key(int64 set_id);
+
+  string get_sticker_set_database_value(const StickerSet *s, bool with_stickers);
+
+  void update_sticker_set(StickerSet *sticker_set);
+
+  void load_sticker_sets(vector<int64> &&sticker_set_ids, Promise<Unit> &&promise);
+
+  void load_sticker_sets_without_stickers(vector<int64> &&sticker_set_ids, Promise<Unit> &&promise);
+
+  void on_load_sticker_set_from_database(int64 sticker_set_id, bool with_stickers, string value);
+
+  void update_load_requests(StickerSet *sticker_set, bool with_stickers, const Status &status);
+
+  void update_load_request(uint32 load_request_id, const Status &status);
+
+  void reload_sticker_set(int64 sticker_set_id, tl_object_ptr<telegram_api::InputStickerSet> &&input_sticker_set,
+                          Promise<Unit> &&promise) const;
+
+  static void read_featured_sticker_sets(void *td_void);
+
+  int32 get_sticker_sets_hash(const vector<int64> &sticker_set_ids) const;
+
+  int32 get_featured_sticker_sets_hash() const;
+
+  int32 get_recent_stickers_hash(const vector<FileId> &sticker_ids) const;
+
+  void load_installed_sticker_sets(bool is_masks, Promise<Unit> &&promise);
+
+  void load_featured_sticker_sets(Promise<Unit> &&promise);
+
+  void load_recent_stickers(bool is_attached, Promise<Unit> &&promise);
+
+  void on_load_installed_sticker_sets_from_database(bool is_masks, string value);
+
+  void on_load_installed_sticker_sets_finished(bool is_masks, vector<int64> &&installed_sticker_set_ids,
+                                               bool from_database = false);
+
+  void on_load_featured_sticker_sets_from_database(string value);
+
+  void on_load_featured_sticker_sets_finished(vector<int64> &&featured_sticker_set_ids);
+
+  void on_load_recent_stickers_from_database(bool is_attached, string value);
+
+  void on_load_recent_stickers_finished(bool is_attached, vector<FileId> &&recent_sticker_ids,
+                                        bool from_database = false);
+
+  void send_update_installed_sticker_sets(bool from_database = false);
+
+  void send_update_featured_sticker_sets();
+
+  void send_update_recent_stickers(bool from_database = false);
+
+  void save_recent_stickers_to_database(bool is_attached);
+
+  void add_recent_sticker_inner(bool is_attached, FileId sticker_id, Promise<Unit> &&promise);
+
+  bool add_recent_sticker_impl(bool is_attached, FileId sticker_id, Promise<Unit> &promise);
+
+  int32 get_favorite_stickers_hash() const;
+
+  void add_favorite_sticker_inner(FileId sticker_id, Promise<Unit> &&promise);
+
+  bool add_favorite_sticker_impl(FileId sticker_id, Promise<Unit> &promise);
+
+  void load_favorite_stickers(Promise<Unit> &&promise);
+
+  void on_load_favorite_stickers_from_database(const string &value);
+
+  void on_load_favorite_stickers_finished(vector<FileId> &&favorite_sticker_ids, bool from_database = false);
+
+  void send_update_favorite_stickers(bool from_database = false);
+
+  void save_favorite_stickers_to_database();
+
+  template <class T>
+  void store_sticker_set(const StickerSet *sticker_set, bool with_stickers, T &storer) const;
+
+  template <class T>
+  void parse_sticker_set(StickerSet *sticker_set, T &parser);
+
+  template <class T>
+  void store_sticker_set_id(int64 sticker_set_id, T &storer) const;
+
+  template <class T>
+  void parse_sticker_set_id(int64 &sticker_set_id, T &parser);
+
+  Result<std::tuple<FileId, bool, bool>> prepare_input_file(const tl_object_ptr<td_api::InputFile> &input_file);
+
+  Result<std::tuple<FileId, bool, bool>> prepare_input_sticker(td_api::inputSticker *sticker);
+
+  tl_object_ptr<telegram_api::inputStickerSetItem> get_input_sticker(td_api::inputSticker *sticker,
+                                                                     FileId file_id) const;
+
+  void upload_sticker_file(UserId user_id, FileId file_id, Promise<Unit> &&promise);
+
+  void on_upload_sticker_file(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file);
+
+  void on_upload_sticker_file_error(FileId file_id, Status status);
+
+  void do_upload_sticker_file(UserId user_id, FileId file_id, tl_object_ptr<telegram_api::InputFile> &&input_file,
+                              Promise<Unit> &&promise);
+
+  void on_new_stickers_uploaded(int64 random_id, Result<Unit> result);
+
+  void on_added_sticker_uploaded(int64 random_id, Result<Unit> result);
+
+  bool update_sticker_set_cache(const StickerSet *sticker_set, Promise<Unit> &promise);
+
+  void tear_down() override;
+
+  static string remove_emoji_modifiers(string emoji);
+
+  Td *td_;
+  ActorShared<> parent_;
+  std::unordered_map<FileId, unique_ptr<Sticker>, FileIdHash> stickers_;  // file_id -> Sticker
+  std::unordered_map<int64, unique_ptr<StickerSet>> sticker_sets_;        // id -> StickerSet
+  std::unordered_map<string, int64> short_name_to_sticker_set_id_;
+
+  vector<int64> installed_sticker_set_ids_[2];
+  vector<int64> featured_sticker_set_ids_;
+  vector<FileId> recent_sticker_ids_[2];
+  vector<FileId> favorite_sticker_ids_;
+
+  double next_installed_sticker_sets_load_time_[2] = {0, 0};
+  double next_featured_sticker_sets_load_time_ = 0;
+  double next_recent_stickers_load_time_[2] = {0, 0};
+  double next_favorite_stickers_load_time_ = 0;
+
+  int32 installed_sticker_sets_hash_[2] = {0, 0};
+  int32 featured_sticker_sets_hash_ = 0;
+  int32 recent_stickers_hash_[2] = {0, 0};
+
+  bool need_update_installed_sticker_sets_[2] = {false, false};
+  bool need_update_featured_sticker_sets_ = false;
+  bool need_update_recent_stickers_[2] = {false, false};
+
+  bool are_installed_sticker_sets_loaded_[2] = {false, false};
+  bool are_featured_sticker_sets_loaded_ = false;
+  bool are_recent_stickers_loaded_[2] = {false, false};
+  bool are_favorite_stickers_loaded_ = false;
+
+  vector<Promise<Unit>> load_installed_sticker_sets_queries_[2];
+  vector<Promise<Unit>> load_featured_sticker_sets_queries_;
+  vector<Promise<Unit>> load_recent_stickers_queries_[2];
+  vector<Promise<Unit>> load_favorite_stickers_queries_;
+
+  vector<int64> archived_sticker_set_ids_[2];
+  int32 total_archived_sticker_set_count_[2] = {-1, -1};
+
+  std::unordered_map<FileId, vector<int64>, FileIdHash> attached_sticker_sets_;
+
+  Hints installed_sticker_sets_hints_[2];  // search installed sticker sets by their title and name
+
+  std::unordered_map<string, vector<FileId>> found_stickers_;
+  std::unordered_map<string, vector<Promise<Unit>>> search_stickers_queries_;
+
+  std::unordered_map<string, vector<int64>> found_sticker_sets_;
+  std::unordered_map<string, vector<Promise<Unit>>> search_sticker_sets_queries_;
+
+  std::unordered_set<int64> pending_viewed_featured_sticker_set_ids_;
+  Timeout pending_featured_sticker_set_views_timeout_;
+
+  int32 recent_stickers_limit_ = 200;
+  int32 favorite_stickers_limit_ = 5;
+
+  struct StickerSetLoadRequest {
+    Promise<Unit> promise;
+    Status error;
+    size_t left_queries;
+  };
+
+  std::unordered_map<uint32, StickerSetLoadRequest> sticker_set_load_requests_;
+  uint32 current_sticker_set_load_request_ = 0;
+
+  std::unordered_map<int64, unique_ptr<PendingNewStickerSet>> pending_new_sticker_sets_;
+
+  std::unordered_map<int64, unique_ptr<PendingAddStickerToSet>> pending_add_sticker_to_sets_;
+
+  std::shared_ptr<UploadStickerFileCallback> upload_sticker_file_callback_;
+
+  std::unordered_map<FileId, std::pair<UserId, Promise<Unit>>, FileIdHash> being_uploaded_files_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/StickersManager.hpp b/libs/tdlib/td/td/telegram/StickersManager.hpp
new file mode 100644
index 0000000000..2bdb3593a7
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/StickersManager.hpp
@@ -0,0 +1,254 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/telegram/StickersManager.h"
+
+#include "td/telegram/files/FileId.hpp"
+#include "td/telegram/misc.h"
+#include "td/telegram/Photo.hpp"
+
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+
+template <class T>
+void StickersManager::store_sticker(FileId file_id, bool in_sticker_set, T &storer) const {
+  auto it = stickers_.find(file_id);
+  CHECK(it != stickers_.end());
+  const Sticker *sticker = it->second.get();
+  bool has_sticker_set_access_hash = sticker->set_id != 0 && !in_sticker_set;
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(sticker->is_mask);
+  STORE_FLAG(has_sticker_set_access_hash);
+  STORE_FLAG(in_sticker_set);
+  END_STORE_FLAGS();
+  if (!in_sticker_set) {
+    store(sticker->set_id, storer);
+    if (has_sticker_set_access_hash) {
+      auto sticker_set = get_sticker_set(sticker->set_id);
+      CHECK(sticker_set != nullptr);
+      store(sticker_set->access_hash, storer);
+    }
+  }
+  store(sticker->alt, storer);
+  store(sticker->dimensions, storer);
+  store(sticker->message_thumbnail, storer);
+  store(sticker->sticker_thumbnail, storer);
+  store(file_id, storer);
+  if (sticker->is_mask) {
+    store(sticker->point, storer);
+    store(sticker->x_shift, storer);
+    store(sticker->y_shift, storer);
+    store(sticker->scale, storer);
+  }
+}
+
+template <class T>
+FileId StickersManager::parse_sticker(bool in_sticker_set, T &parser) {
+  auto sticker = make_unique<Sticker>();
+  bool has_sticker_set_access_hash;
+  bool in_sticker_set_stored;
+  BEGIN_PARSE_FLAGS();
+  PARSE_FLAG(sticker->is_mask);
+  PARSE_FLAG(has_sticker_set_access_hash);
+  PARSE_FLAG(in_sticker_set_stored);
+  END_PARSE_FLAGS();
+  CHECK(in_sticker_set_stored == in_sticker_set) << in_sticker_set << " " << in_sticker_set_stored;
+  if (!in_sticker_set) {
+    parse(sticker->set_id, parser);
+    if (has_sticker_set_access_hash) {
+      int64 sticker_set_access_hash;
+      parse(sticker_set_access_hash, parser);
+      add_sticker_set(sticker->set_id, sticker_set_access_hash);
+    } else {
+      // backward compatibility
+      sticker->set_id = 0;
+    }
+  }
+  parse(sticker->alt, parser);
+  parse(sticker->dimensions, parser);
+  parse(sticker->message_thumbnail, parser);
+  parse(sticker->sticker_thumbnail, parser);
+  parse(sticker->file_id, parser);
+  if (sticker->is_mask) {
+    parse(sticker->point, parser);
+    parse(sticker->x_shift, parser);
+    parse(sticker->y_shift, parser);
+    parse(sticker->scale, parser);
+  }
+  return on_get_sticker(std::move(sticker), true);
+}
+
+template <class T>
+void StickersManager::store_sticker_set(const StickerSet *sticker_set, bool with_stickers, T &storer) const {
+  size_t stickers_limit = with_stickers ? sticker_set->sticker_ids.size() : 5;
+  bool is_full = sticker_set->sticker_ids.size() <= stickers_limit;
+  bool was_loaded = sticker_set->was_loaded && is_full;
+  bool is_loaded = sticker_set->is_loaded && is_full;
+  bool has_expires_at = !sticker_set->is_installed && sticker_set->expires_at != 0;
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(sticker_set->is_inited);
+  STORE_FLAG(was_loaded);
+  STORE_FLAG(is_loaded);
+  STORE_FLAG(sticker_set->is_installed);
+  STORE_FLAG(sticker_set->is_archived);
+  STORE_FLAG(sticker_set->is_official);
+  STORE_FLAG(sticker_set->is_masks);
+  STORE_FLAG(sticker_set->is_viewed);
+  STORE_FLAG(has_expires_at);
+  END_STORE_FLAGS();
+  store(sticker_set->id, storer);
+  store(sticker_set->access_hash, storer);
+  if (sticker_set->is_inited) {
+    store(sticker_set->title, storer);
+    store(sticker_set->short_name, storer);
+    store(sticker_set->sticker_count, storer);
+    store(sticker_set->hash, storer);
+    if (has_expires_at) {
+      store(sticker_set->expires_at, storer);
+    }
+
+    uint32 stored_sticker_count = narrow_cast<uint32>(is_full ? sticker_set->sticker_ids.size() : stickers_limit);
+    store(stored_sticker_count, storer);
+    for (uint32 i = 0; i < stored_sticker_count; i++) {
+      auto sticker_id = sticker_set->sticker_ids[i];
+      store_sticker(sticker_id, true, storer);
+
+      if (was_loaded) {
+        auto it = sticker_set->sticker_emojis_map_.find(sticker_id);
+        if (it != sticker_set->sticker_emojis_map_.end()) {
+          store(it->second, storer);
+        } else {
+          store(vector<string>(), storer);
+        }
+      }
+    }
+  }
+}
+
+template <class T>
+void StickersManager::parse_sticker_set(StickerSet *sticker_set, T &parser) {
+  CHECK(sticker_set != nullptr);
+  CHECK(!sticker_set->was_loaded);
+  bool was_inited = sticker_set->is_inited;
+  bool is_installed;
+  bool is_archived;
+  bool is_official;
+  bool is_masks;
+  bool has_expires_at;
+  BEGIN_PARSE_FLAGS();
+  PARSE_FLAG(sticker_set->is_inited);
+  PARSE_FLAG(sticker_set->was_loaded);
+  PARSE_FLAG(sticker_set->is_loaded);
+  PARSE_FLAG(is_installed);
+  PARSE_FLAG(is_archived);
+  PARSE_FLAG(is_official);
+  PARSE_FLAG(is_masks);
+  PARSE_FLAG(sticker_set->is_viewed);
+  PARSE_FLAG(has_expires_at);
+  END_PARSE_FLAGS();
+  int64 sticker_set_id;
+  int64 access_hash;
+  parse(sticker_set_id, parser);
+  parse(access_hash, parser);
+  CHECK(sticker_set->id == sticker_set_id);
+  if (sticker_set->access_hash != access_hash) {
+    LOG(ERROR) << "Sticker set " << sticker_set_id << " access hash has changed from " << access_hash << " to "
+               << sticker_set->access_hash;
+  }
+
+  if (sticker_set->is_inited) {
+    string title;
+    string short_name;
+    int32 sticker_count;
+    int32 hash;
+    int32 expires_at = 0;
+    parse(title, parser);
+    parse(short_name, parser);
+    parse(sticker_count, parser);
+    parse(hash, parser);
+    if (has_expires_at) {
+      parse(expires_at, parser);
+    }
+    if (!was_inited) {
+      sticker_set->title = std::move(title);
+      sticker_set->short_name = std::move(short_name);
+      sticker_set->sticker_count = sticker_count;
+      sticker_set->hash = hash;
+      sticker_set->expires_at = expires_at;
+      sticker_set->is_official = is_official;
+      sticker_set->is_masks = is_masks;
+
+      short_name_to_sticker_set_id_.emplace(clean_username(sticker_set->short_name), sticker_set_id);
+      on_update_sticker_set(sticker_set, is_installed, is_archived, false, true);
+    } else {
+      if (sticker_set->title != title) {
+        LOG(INFO) << "Sticker set " << sticker_set_id << " title has changed";
+      }
+      if (sticker_set->short_name != short_name) {
+        LOG(ERROR) << "Sticker set " << sticker_set_id << " short name has changed from \"" << short_name << "\" to \""
+                   << sticker_set->short_name << "\"";
+      }
+      if (sticker_set->sticker_count != sticker_count || sticker_set->hash != hash) {
+        sticker_set->is_loaded = false;
+      }
+    }
+
+    uint32 stored_sticker_count;
+    parse(stored_sticker_count, parser);
+    sticker_set->sticker_ids.clear();
+    if (sticker_set->was_loaded) {
+      sticker_set->emoji_stickers_map_.clear();
+      sticker_set->sticker_emojis_map_.clear();
+    }
+    for (uint32 i = 0; i < stored_sticker_count; i++) {
+      auto sticker_id = parse_sticker(true, parser);
+      sticker_set->sticker_ids.push_back(sticker_id);
+
+      Sticker *sticker = get_sticker(sticker_id);
+      CHECK(sticker != nullptr);
+      if (sticker->set_id != sticker_set->id) {
+        LOG_IF(ERROR, sticker->set_id != 0) << "Sticker " << sticker_id << " set_id has changed";
+        sticker->set_id = sticker_set->id;
+        sticker->is_changed = true;
+      }
+
+      if (sticker_set->was_loaded) {
+        vector<string> emojis;
+        parse(emojis, parser);
+        for (auto &emoji : emojis) {
+          sticker_set->emoji_stickers_map_[remove_emoji_modifiers(emoji)].push_back(sticker_id);
+        }
+        sticker_set->sticker_emojis_map_[sticker_id] = std::move(emojis);
+      }
+    }
+    if (expires_at > sticker_set->expires_at) {
+      sticker_set->expires_at = expires_at;
+    }
+  }
+}
+
+template <class T>
+void StickersManager::store_sticker_set_id(int64 sticker_set_id, T &storer) const {
+  CHECK(sticker_set_id != 0);
+  const StickerSet *sticker_set = get_sticker_set(sticker_set_id);
+  CHECK(sticker_set != nullptr);
+  store(sticker_set_id, storer);
+  store(sticker_set->access_hash, storer);
+}
+
+template <class T>
+void StickersManager::parse_sticker_set_id(int64 &sticker_set_id, T &parser) {
+  parse(sticker_set_id, parser);
+  int64 sticker_set_access_hash;
+  parse(sticker_set_access_hash, parser);
+  add_sticker_set(sticker_set_id, sticker_set_access_hash);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/StorageManager.cpp b/libs/tdlib/td/td/telegram/StorageManager.cpp
new file mode 100644
index 0000000000..de68743e6c
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/StorageManager.cpp
@@ -0,0 +1,254 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/StorageManager.h"
+
+#include "td/telegram/ConfigShared.h"
+#include "td/telegram/DialogId.h"
+#include "td/telegram/files/FileGcWorker.h"
+#include "td/telegram/files/FileStatsWorker.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/logevent/LogEvent.h"
+#include "td/telegram/MessagesManager.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/Clocks.h"
+#include "td/utils/port/Stat.h"
+#include "td/utils/Random.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Time.h"
+
+namespace td {
+StorageManager::StorageManager(ActorShared<> parent, int32 scheduler_id)
+    : parent_(std::move(parent)), scheduler_id_(scheduler_id) {
+}
+
+void StorageManager::start_up() {
+  load_last_gc_timestamp();
+  schedule_next_gc();
+
+  load_fast_stat();
+}
+void StorageManager::on_new_file(int64 size) {
+  if (size > 0) {
+    fast_stat_.cnt++;
+  } else {
+    fast_stat_.cnt--;
+  }
+  fast_stat_.size += size;
+
+  if (fast_stat_.cnt < 0 || fast_stat_.size < 0) {
+    LOG(ERROR) << "Wrong fast stat after adding size " << size;
+    fast_stat_ = FileTypeStat();
+  }
+  save_fast_stat();
+}
+void StorageManager::get_storage_stats(int32 dialog_limit, Promise<FileStats> promise) {
+  if (pending_storage_stats_.size() != 0) {
+    promise.set_error(Status::Error(400, "Another storage stats is active"));
+    return;
+  }
+  stats_dialog_limit_ = dialog_limit;
+  pending_storage_stats_.emplace_back(std::move(promise));
+
+  create_stats_worker();
+  send_closure(stats_worker_, &FileStatsWorker::get_stats, false /*need_all_files*/, stats_dialog_limit_ != 0,
+               PromiseCreator::lambda([actor_id = actor_id(this)](Result<FileStats> file_stats) {
+                 send_closure(actor_id, &StorageManager::on_file_stats, std::move(file_stats), false);
+               }));
+}
+
+void StorageManager::get_storage_stats_fast(Promise<FileStatsFast> promise) {
+  promise.set_value(FileStatsFast(fast_stat_.size, fast_stat_.cnt, get_db_size()));
+}
+
+void StorageManager::update_use_storage_optimizer() {
+  schedule_next_gc();
+}
+
+void StorageManager::run_gc(FileGcParameters parameters, Promise<FileStats> promise) {
+  if (pending_run_gc_.size() != 0) {
+    promise.set_error(Status::Error(400, "Another gc is active"));
+    return;
+  }
+
+  pending_run_gc_.emplace_back(std::move(promise));
+  if (pending_run_gc_.size() > 1) {
+    return;
+  }
+
+  gc_parameters_ = std::move(parameters);
+
+  create_stats_worker();
+  send_closure(stats_worker_, &FileStatsWorker::get_stats, true /*need_all_file*/,
+               !gc_parameters_.owner_dialog_ids.empty() || !gc_parameters_.exclude_owner_dialog_ids.empty() ||
+                   gc_parameters_.dialog_limit != 0 /*split_by_owner_dialog_id*/,
+               PromiseCreator::lambda([actor_id = actor_id(this)](Result<FileStats> file_stats) {
+                 send_closure(actor_id, &StorageManager::on_all_files, std::move(file_stats), false);
+               }));
+}
+
+void StorageManager::on_file_stats(Result<FileStats> r_file_stats, bool dummy) {
+  if (r_file_stats.is_error()) {
+    auto promises = std::move(pending_storage_stats_);
+    for (auto &promise : promises) {
+      promise.set_error(r_file_stats.error().clone());
+    }
+    return;
+  }
+
+  send_stats(r_file_stats.move_as_ok(), stats_dialog_limit_, std::move(pending_storage_stats_));
+}
+
+void StorageManager::create_stats_worker() {
+  if (stats_worker_.empty()) {
+    stats_worker_ = create_actor_on_scheduler<FileStatsWorker>("FileStatsWorker", scheduler_id_, create_reference());
+  }
+}
+
+void StorageManager::on_all_files(Result<FileStats> r_file_stats, bool dummy) {
+  if (r_file_stats.is_error()) {
+    LOG(ERROR) << "Stats for GC failed: " << r_file_stats.error();
+    auto promises = std::move(pending_run_gc_);
+    for (auto &promise : promises) {
+      promise.set_error(r_file_stats.error().clone());
+    }
+    return;
+  }
+
+  create_gc_worker();
+
+  send_closure(gc_worker_, &FileGcWorker::run_gc, gc_parameters_, r_file_stats.move_as_ok().all_files,
+               PromiseCreator::lambda([actor_id = actor_id(this)](Result<FileStats> r_file_stats) {
+                 send_closure(actor_id, &StorageManager::on_gc_finished, std::move(r_file_stats), false);
+               }));
+}
+
+int64 StorageManager::get_db_size() {
+  int64 size = 0;
+  auto add_path = [&](CSlice path) {
+    TRY_RESULT(info, stat(path));
+    size += info.size_;
+
+    return Status::OK();
+  };
+
+  G()->td_db()->with_db_path([&](CSlice path) { add_path(path).ignore(); });
+  add_path(G()->parameters().database_directory + "log").ignore();
+  add_path(G()->parameters().database_directory + "log.old").ignore();
+  return size;
+}
+
+void StorageManager::create_gc_worker() {
+  if (gc_worker_.empty()) {
+    gc_worker_ = create_actor_on_scheduler<FileGcWorker>("FileGcWorker", scheduler_id_, create_reference());
+  }
+}
+
+void StorageManager::on_gc_finished(Result<FileStats> r_file_stats, bool dummy) {
+  if (r_file_stats.is_error()) {
+    LOG(ERROR) << "GC failed: " << r_file_stats.error();
+    auto promises = std::move(pending_run_gc_);
+    for (auto &promise : promises) {
+      promise.set_error(r_file_stats.error().clone());
+    }
+    return;
+  }
+
+  send_stats(r_file_stats.move_as_ok(), gc_parameters_.dialog_limit, std::move(pending_run_gc_));
+}
+
+void StorageManager::save_fast_stat() {
+  G()->td_db()->get_binlog_pmc()->set("fast_file_stat", log_event_store(fast_stat_).as_slice().str());
+}
+void StorageManager::load_fast_stat() {
+  auto status = log_event_parse(fast_stat_, G()->td_db()->get_binlog_pmc()->get("fast_file_stat"));
+  if (status.is_error()) {
+    fast_stat_ = FileTypeStat();
+  }
+}
+
+void StorageManager::send_stats(FileStats &&stats, int32 dialog_limit, std::vector<Promise<FileStats>> promises) {
+  fast_stat_ = stats.get_total_nontemp_stat();
+  save_fast_stat();
+
+  stats.apply_dialog_limit(dialog_limit);
+  std::vector<DialogId> dialog_ids = stats.get_dialog_ids();
+
+  auto promise =
+      PromiseCreator::lambda([promises = std::move(promises), stats = std::move(stats)](Result<Unit>) mutable {
+        for (auto &promise : promises) {
+          promise.set_value(FileStats(stats));
+        }
+      });
+
+  send_closure(G()->messages_manager(), &MessagesManager::load_dialogs, std::move(dialog_ids), std::move(promise));
+}
+
+ActorShared<> StorageManager::create_reference() {
+  return actor_shared(this, 1);
+}
+
+void StorageManager::hangup_shared() {
+  ref_cnt_--;
+  if (ref_cnt_ == 0) {
+    stop();
+  }
+}
+
+void StorageManager::hangup() {
+  hangup_shared();
+}
+
+uint32 StorageManager::load_last_gc_timestamp() {
+  last_gc_timestamp_ = to_integer<uint32>(G()->td_db()->get_binlog_pmc()->get("files_gc_ts"));
+  return last_gc_timestamp_;
+}
+void StorageManager::save_last_gc_timestamp() {
+  last_gc_timestamp_ = static_cast<uint32>(Clocks::system());
+  G()->td_db()->get_binlog_pmc()->set("files_gc_ts", to_string(last_gc_timestamp_));
+}
+void StorageManager::schedule_next_gc() {
+  if (!G()->shared_config().get_option_boolean("use_storage_optimizer") &&
+      !G()->parameters().enable_storage_optimizer) {
+    next_gc_at_ = 0;
+    cancel_timeout();
+    LOG(INFO) << "No next file gc is scheduled";
+    return;
+  }
+  auto sys_time = static_cast<uint32>(Clocks::system());
+
+  auto next_gc_at = last_gc_timestamp_ + GC_EACH;
+  if (next_gc_at < sys_time) {
+    next_gc_at = sys_time;
+  }
+  if (next_gc_at > sys_time + GC_EACH) {
+    next_gc_at = sys_time + GC_EACH;
+  }
+  next_gc_at += Random::fast(GC_DELAY, GC_DELAY + GC_RAND_DELAY);
+  CHECK(next_gc_at >= sys_time);
+  auto next_gc_in = next_gc_at - sys_time;
+
+  LOG(INFO) << "Schedule next file gc in " << next_gc_in;
+  next_gc_at_ = Time::now() + next_gc_in;
+  set_timeout_at(next_gc_at_);
+}
+
+void StorageManager::timeout_expired() {
+  if (next_gc_at_ == 0) {
+    return;
+  }
+  next_gc_at_ = 0;
+  run_gc({}, PromiseCreator::lambda([actor_id = actor_id(this)](Result<FileStats> r_stats) {
+           if (!r_stats.is_error() || r_stats.error().code() != 1) {
+             send_closure(actor_id, &StorageManager::save_last_gc_timestamp);
+           }
+           send_closure(actor_id, &StorageManager::schedule_next_gc);
+         }));
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/StorageManager.h b/libs/tdlib/td/td/telegram/StorageManager.h
new file mode 100644
index 0000000000..48185b9081
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/StorageManager.h
@@ -0,0 +1,82 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/files/FileGcWorker.h"
+#include "td/telegram/files/FileStats.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Status.h"
+
+namespace td {
+class FileStatsWorker;
+class FileGcWorker;
+}  // namespace td
+
+namespace td {
+class StorageManager : public Actor {
+ public:
+  StorageManager(ActorShared<> parent, int32 scheduler_id);
+  void get_storage_stats(int32 dialog_limit, Promise<FileStats> promise);
+  void get_storage_stats_fast(Promise<FileStatsFast> promise);
+  void run_gc(FileGcParameters parameters, Promise<FileStats> promise);
+  void update_use_storage_optimizer();
+  void on_new_file(int64 size);
+
+ private:
+  static constexpr uint32 GC_EACH = 60 * 60 * 24;  // 1 day
+  static constexpr uint32 GC_DELAY = 60;
+  static constexpr uint32 GC_RAND_DELAY = 60 * 15;
+
+  ActorShared<> parent_;
+
+  int32 scheduler_id_;
+
+  // get stats
+  ActorOwn<FileStatsWorker> stats_worker_;
+  std::vector<Promise<FileStats>> pending_storage_stats_;
+  int32 stats_dialog_limit_ = 0;
+
+  FileTypeStat fast_stat_;
+
+  void on_file_stats(Result<FileStats> r_file_stats, bool dummy);
+  void create_stats_worker();
+  void send_stats(FileStats &&stats, int32 dialog_limit, std::vector<Promise<FileStats>> promises);
+
+  void save_fast_stat();
+  void load_fast_stat();
+  static int64 get_db_size();
+
+  // RefCnt
+  int32 ref_cnt_{1};
+  ActorShared<> create_reference();
+  void start_up() override;
+  void hangup_shared() override;
+  void hangup() override;
+
+  // Gc
+  ActorOwn<FileGcWorker> gc_worker_;
+  std::vector<Promise<FileStats>> pending_run_gc_;
+  FileGcParameters gc_parameters_;
+
+  uint32 last_gc_timestamp_ = 0;
+  double next_gc_at_ = 0;
+
+  void on_all_files(Result<FileStats> r_file_stats, bool dummy);
+  void create_gc_worker();
+  void on_gc_finished(Result<FileStats> r_file_stats, bool dummy);
+
+  uint32 load_last_gc_timestamp();
+  void save_last_gc_timestamp();
+  void schedule_next_gc();
+
+  void timeout_expired() override;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Td.cpp b/libs/tdlib/td/td/telegram/Td.cpp
new file mode 100644
index 0000000000..a150e6cca7
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Td.cpp
@@ -0,0 +1,7036 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/Td.h"
+
+#include "td/db/binlog/BinlogEvent.h"
+
+#include "td/telegram/net/ConnectionCreator.h"
+#include "td/telegram/net/MtprotoHeader.h"
+#include "td/telegram/net/NetQuery.h"
+#include "td/telegram/net/NetQueryDelayer.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+#include "td/telegram/net/NetStatsManager.h"
+#include "td/telegram/net/TempAuthKeyWatchdog.h"
+
+#include "td/telegram/AccessRights.h"
+#include "td/telegram/AnimationsManager.h"
+#include "td/telegram/AudiosManager.h"
+#include "td/telegram/AuthManager.h"
+#include "td/telegram/CallbackQueriesManager.h"
+#include "td/telegram/CallId.h"
+#include "td/telegram/CallManager.h"
+#include "td/telegram/ChannelId.h"
+#include "td/telegram/ChatId.h"
+#include "td/telegram/ConfigManager.h"
+#include "td/telegram/ConfigShared.h"
+#include "td/telegram/ContactsManager.h"
+#include "td/telegram/DeviceTokenManager.h"
+#include "td/telegram/DialogId.h"
+#include "td/telegram/DialogParticipant.h"
+#include "td/telegram/DocumentsManager.h"
+#include "td/telegram/files/FileGcParameters.h"
+#include "td/telegram/files/FileId.h"
+#include "td/telegram/files/FileManager.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/HashtagHints.h"
+#include "td/telegram/InlineQueriesManager.h"
+#include "td/telegram/MessageEntity.h"
+#include "td/telegram/MessageId.h"
+#include "td/telegram/MessagesManager.h"
+#include "td/telegram/misc.h"
+#include "td/telegram/PasswordManager.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/PrivacyManager.h"
+#include "td/telegram/SecretChatId.h"
+#include "td/telegram/SecretChatsManager.h"
+#include "td/telegram/StateManager.h"
+#include "td/telegram/StickersManager.h"
+#include "td/telegram/StorageManager.h"
+#include "td/telegram/TdDb.h"
+#include "td/telegram/TopDialogManager.h"
+#include "td/telegram/UpdatesManager.h"
+#include "td/telegram/VideoNotesManager.h"
+#include "td/telegram/VideosManager.h"
+#include "td/telegram/VoiceNotesManager.h"
+#include "td/telegram/WebPageId.h"
+#include "td/telegram/WebPagesManager.h"
+
+#include "td/telegram/td_api.hpp"
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/mtproto/utils.h"  // for create_storer, fetch_result, etc, TODO
+
+#include "td/utils/buffer.h"
+#include "td/utils/format.h"
+#include "td/utils/MimeType.h"
+#include "td/utils/misc.h"
+#include "td/utils/PathView.h"
+#include "td/utils/port/path.h"
+#include "td/utils/Random.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/Timer.h"
+#include "td/utils/tl_parsers.h"
+#include "td/utils/utf8.h"
+
+#include <limits>
+#include <tuple>
+#include <type_traits>
+
+namespace td {
+namespace {
+DbKey as_db_key(string key) {
+  // Database will still be effectively not encrypted, but
+  // 1. sqlite db will be protected from corruption, because that's how sqlcipher works
+  // 2. security through obscurity
+  // 3. no need for reencryption of sqlite db
+  if (key.empty()) {
+    return DbKey::raw_key("cucumber");
+  }
+  return DbKey::raw_key(std::move(key));
+}
+}  // namespace
+
+void Td::ResultHandler::set_td(Td *new_td) {
+  CHECK(td == nullptr);
+  td = new_td;
+}
+
+void Td::ResultHandler::on_result(NetQueryPtr query) {
+  CHECK(query->is_ready());
+  if (query->is_ok()) {
+    on_result(query->id(), std::move(query->ok()));
+  } else {
+    on_error(query->id(), std::move(query->error()));
+  }
+  query->clear();
+}
+
+void Td::ResultHandler::send_query(NetQueryPtr query) {
+  td->add_handler(query->id(), shared_from_this());
+  td->send(std::move(query));
+}
+
+class GetNearestDcQuery : public Td::ResultHandler {
+  Promise<string> promise_;
+
+ public:
+  explicit GetNearestDcQuery(Promise<string> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::help_getNearestDc()), DcId::main(),
+                                               NetQuery::Type::Common, NetQuery::AuthFlag::Off));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::help_getNearestDc>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    promise_.set_value(std::move(result_ptr.ok()->country_));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(ERROR) << "GetNearestDc returned " << status;
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetWallpapersQuery : public Td::ResultHandler {
+  Promise<tl_object_ptr<td_api::wallpapers>> promise_;
+
+ public:
+  explicit GetWallpapersQuery(Promise<tl_object_ptr<td_api::wallpapers>> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::account_getWallPapers())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::account_getWallPapers>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto wallpapers = result_ptr.move_as_ok();
+
+    auto results = make_tl_object<td_api::wallpapers>();
+    results->wallpapers_.reserve(wallpapers.size());
+    for (auto &wallpaper_ptr : wallpapers) {
+      CHECK(wallpaper_ptr != nullptr);
+      switch (wallpaper_ptr->get_id()) {
+        case telegram_api::wallPaper::ID: {
+          auto wallpaper = move_tl_object_as<telegram_api::wallPaper>(wallpaper_ptr);
+          vector<tl_object_ptr<td_api::photoSize>> sizes;
+          sizes.reserve(wallpaper->sizes_.size());
+          for (auto &size_ptr : wallpaper->sizes_) {
+            auto photo_size =
+                get_photo_size(td->file_manager_.get(), FileType::Wallpaper, 0, 0, DialogId(), std::move(size_ptr));
+            sizes.push_back(get_photo_size_object(td->file_manager_.get(), &photo_size));
+          }
+          sort_photo_sizes(sizes);
+          results->wallpapers_.push_back(
+              make_tl_object<td_api::wallpaper>(wallpaper->id_, std::move(sizes), wallpaper->color_));
+          break;
+        }
+        case telegram_api::wallPaperSolid::ID: {
+          auto wallpaper = move_tl_object_as<telegram_api::wallPaperSolid>(wallpaper_ptr);
+          results->wallpapers_.push_back(make_tl_object<td_api::wallpaper>(
+              wallpaper->id_, vector<tl_object_ptr<td_api::photoSize>>(), wallpaper->bg_color_));
+          break;
+        }
+        default:
+          UNREACHABLE();
+      }
+    }
+    promise_.set_value(std::move(results));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetRecentMeUrlsQuery : public Td::ResultHandler {
+  Promise<tl_object_ptr<td_api::tMeUrls>> promise_;
+
+ public:
+  explicit GetRecentMeUrlsQuery(Promise<tl_object_ptr<td_api::tMeUrls>> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(const string &referrer) {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::help_getRecentMeUrls(referrer))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::help_getRecentMeUrls>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto urls_full = result_ptr.move_as_ok();
+    td->contacts_manager_->on_get_users(std::move(urls_full->users_));
+    td->contacts_manager_->on_get_chats(std::move(urls_full->chats_));
+
+    auto urls = std::move(urls_full->urls_);
+    auto results = make_tl_object<td_api::tMeUrls>();
+    results->urls_.reserve(urls.size());
+    for (auto &url_ptr : urls) {
+      CHECK(url_ptr != nullptr);
+      tl_object_ptr<td_api::tMeUrl> result = make_tl_object<td_api::tMeUrl>();
+      switch (url_ptr->get_id()) {
+        case telegram_api::recentMeUrlUser::ID: {
+          auto url = move_tl_object_as<telegram_api::recentMeUrlUser>(url_ptr);
+          result->url_ = std::move(url->url_);
+          UserId user_id(url->user_id_);
+          if (!user_id.is_valid()) {
+            LOG(ERROR) << "Receive invalid " << user_id;
+            result = nullptr;
+            break;
+          }
+          result->type_ = make_tl_object<td_api::tMeUrlTypeUser>(
+              td->contacts_manager_->get_user_id_object(user_id, "tMeUrlTypeUser"));
+          break;
+        }
+        case telegram_api::recentMeUrlChat::ID: {
+          auto url = move_tl_object_as<telegram_api::recentMeUrlChat>(url_ptr);
+          result->url_ = std::move(url->url_);
+          ChannelId channel_id(url->chat_id_);
+          if (!channel_id.is_valid()) {
+            LOG(ERROR) << "Receive invalid " << channel_id;
+            result = nullptr;
+            break;
+          }
+          result->type_ = make_tl_object<td_api::tMeUrlTypeSupergroup>(
+              td->contacts_manager_->get_supergroup_id_object(channel_id, "tMeUrlTypeSupergroup"));
+          break;
+        }
+        case telegram_api::recentMeUrlChatInvite::ID: {
+          auto url = move_tl_object_as<telegram_api::recentMeUrlChatInvite>(url_ptr);
+          result->url_ = std::move(url->url_);
+          td->contacts_manager_->on_get_dialog_invite_link_info(result->url_, std::move(url->chat_invite_));
+          result->type_ = make_tl_object<td_api::tMeUrlTypeChatInvite>(
+              td->contacts_manager_->get_chat_invite_link_info_object(result->url_));
+          break;
+        }
+        case telegram_api::recentMeUrlStickerSet::ID: {
+          auto url = move_tl_object_as<telegram_api::recentMeUrlStickerSet>(url_ptr);
+          result->url_ = std::move(url->url_);
+          auto sticker_set_id = td->stickers_manager_->on_get_sticker_set_covered(std::move(url->set_), false);
+          if (sticker_set_id == 0) {
+            LOG(ERROR) << "Receive invalid sticker set";
+            result = nullptr;
+            break;
+          }
+          result->type_ = make_tl_object<td_api::tMeUrlTypeStickerSet>(sticker_set_id);
+          break;
+        }
+        case telegram_api::recentMeUrlUnknown::ID:
+          // skip
+          result = nullptr;
+          break;
+        default:
+          UNREACHABLE();
+      }
+      if (result != nullptr) {
+        results->urls_.push_back(std::move(result));
+      }
+    }
+    promise_.set_value(std::move(results));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SendCustomRequestQuery : public Td::ResultHandler {
+  Promise<string> promise_;
+
+ public:
+  explicit SendCustomRequestQuery(Promise<string> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(const string &method, const string &parameters) {
+    send_query(G()->net_query_creator().create(create_storer(
+        telegram_api::bots_sendCustomRequest(method, make_tl_object<telegram_api::dataJSON>(parameters)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::bots_sendCustomRequest>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    promise_.set_value(std::move(result_ptr.ok()->data_));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class AnswerCustomQueryQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit AnswerCustomQueryQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(int64 custom_query_id, const string &data) {
+    send_query(G()->net_query_creator().create(create_storer(
+        telegram_api::bots_answerWebhookJSONQuery(custom_query_id, make_tl_object<telegram_api::dataJSON>(data)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::bots_answerWebhookJSONQuery>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    if (!result) {
+      LOG(INFO) << "Sending answer to a custom query has failed";
+    }
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SetBotUpdatesStatusQuery : public Td::ResultHandler {
+ public:
+  void send(int32 pending_update_count, const string &error_message) {
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::help_setBotUpdatesStatus(pending_update_count, error_message))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::help_setBotUpdatesStatus>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    LOG_IF(WARNING, !result) << "Set bot updates status has failed";
+  }
+
+  void on_error(uint64 id, Status status) override {
+    LOG(WARNING) << "Receive error for SetBotUpdatesStatus: " << status;
+    status.ignore();
+  }
+};
+
+class UpdateStatusQuery : public Td::ResultHandler {
+  bool is_offline_;
+
+ public:
+  NetQueryRef send(bool is_offline) {
+    is_offline_ = is_offline;
+    auto net_query = G()->net_query_creator().create(create_storer(telegram_api::account_updateStatus(is_offline)));
+    auto result = net_query.get_weak();
+    send_query(std::move(net_query));
+    return result;
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::account_updateStatus>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.ok();
+    LOG(INFO) << "UpdateStatus returned " << result;
+    td->on_update_status_success(!is_offline_);
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.code() != NetQuery::Cancelled) {
+      LOG(ERROR) << "Receive error for UpdateStatusQuery: " << status;
+    }
+    status.ignore();
+  }
+};
+
+class GetInviteTextQuery : public Td::ResultHandler {
+  Promise<string> promise_;
+
+ public:
+  explicit GetInviteTextQuery(Promise<string> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::help_getInviteText())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::help_getInviteText>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    promise_.set_value(std::move(result_ptr.ok()->message_));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class GetTermsOfServiceQuery : public Td::ResultHandler {
+  Promise<string> promise_;
+
+ public:
+  explicit GetTermsOfServiceQuery(Promise<string> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::help_getTermsOfService()), DcId::main(),
+                                               NetQuery::Type::Common, NetQuery::AuthFlag::Off));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::help_getTermsOfService>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    promise_.set_value(std::move(result_ptr.ok()->text_));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+template <class T = Unit>
+class RequestActor : public Actor {
+ public:
+  RequestActor(ActorShared<Td> td_id, uint64 request_id)
+      : td_id_(std::move(td_id)), td(td_id_.get().get_actor_unsafe()), request_id_(request_id) {
+  }
+
+  void loop() override {
+    PromiseActor<T> promise;
+    FutureActor<T> future;
+    init_promise_future(&promise, &future);
+
+    do_run(PromiseCreator::from_promise_actor(std::move(promise)));
+
+    if (future.is_ready()) {
+      if (future.is_error()) {
+        do_send_error(future.move_as_error());
+      } else {
+        do_set_result(future.move_as_ok());
+        do_send_result();
+      }
+      stop();
+    } else {
+      if (--tries_left_ == 0) {
+        future.close();
+        do_send_error(Status::Error(400, "Requested data is unaccessible"));
+        return stop();
+      }
+
+      future.set_event(EventCreator::raw(actor_id(), nullptr));
+      future_ = std::move(future);
+    }
+  }
+
+  void raw_event(const Event::Raw &event) override {
+    if (future_.is_error()) {
+      auto error = future_.move_as_error();
+      if (error == Status::Hangup()) {
+        // dropping query due to lost authorization or lost promise
+        // td may be already closed, so we should check is auth_manager_ is empty
+        bool is_authorized = td->auth_manager_ && td->auth_manager_->is_authorized();
+        if (is_authorized) {
+          LOG(ERROR) << "Promise was lost";
+          do_send_error(Status::Error(500, "Query can't be answered due to bug in the TDLib"));
+        } else {
+          do_send_error(Status::Error(401, "Unauthorized"));
+        }
+        return stop();
+      }
+
+      do_send_error(std::move(error));
+      stop();
+    } else {
+      do_set_result(future_.move_as_ok());
+      loop();
+    }
+  }
+
+  void on_start_migrate(int32 /*sched_id*/) override {
+    UNREACHABLE();
+  }
+  void on_finish_migrate() override {
+    UNREACHABLE();
+  }
+
+  int get_tries() const {
+    return tries_left_;
+  }
+
+  void set_tries(int32 tries) {
+    tries_left_ = tries;
+  }
+
+ protected:
+  ActorShared<Td> td_id_;
+  Td *td;
+
+  void send_result(tl_object_ptr<td_api::Object> &&result) {
+    send_closure(td_id_, &Td::send_result, request_id_, std::move(result));
+  }
+
+  void send_error(Status &&status) {
+    LOG(INFO) << "Receive error for query: " << status;
+    send_closure(td_id_, &Td::send_error, request_id_, std::move(status));
+  }
+
+ private:
+  virtual void do_run(Promise<T> &&promise) = 0;
+
+  virtual void do_send_result() {
+    send_result(make_tl_object<td_api::ok>());
+  }
+
+  virtual void do_send_error(Status &&status) {
+    send_error(std::move(status));
+  }
+
+  virtual void do_set_result(T &&result) {
+    CHECK((std::is_same<T, Unit>::value));  // all other results should be implicitly handled by overriding this method
+  }
+
+  void hangup() override {
+    do_send_error(Status::Error(500, "Request aborted"));
+    stop();
+  }
+
+  friend class RequestOnceActor;
+
+  uint64 request_id_;
+  int tries_left_ = 2;
+  FutureActor<T> future_;
+};
+
+class RequestOnceActor : public RequestActor<> {
+ public:
+  RequestOnceActor(ActorShared<Td> td_id, uint64 request_id) : RequestActor(std::move(td_id), request_id) {
+  }
+
+  void loop() override {
+    if (get_tries() < 2) {
+      do_send_result();
+      stop();
+      return;
+    }
+
+    RequestActor::loop();
+  }
+};
+
+/*** Td ***/
+/** Td queries **/
+class TestQuery : public Td::ResultHandler {
+ public:
+  explicit TestQuery(uint64 request_id) : request_id_(request_id) {
+  }
+
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::help_getConfig())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::help_getConfig>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, Status::Error(500, "Fetch failed"));
+    }
+
+    LOG(DEBUG) << "TestOK: " << to_string(result_ptr.ok());
+    send_closure(G()->td(), &Td::send_result, request_id_, make_tl_object<td_api::ok>());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    status.ignore();
+    LOG(ERROR) << "Test query failed: " << status;
+  }
+
+ private:
+  uint64 request_id_;
+};
+
+class GetAccountTtlRequest : public RequestActor<int32> {
+  int32 account_ttl_;
+
+  void do_run(Promise<int32> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(account_ttl_));
+      return;
+    }
+
+    td->contacts_manager_->get_account_ttl(std::move(promise));
+  }
+
+  void do_set_result(int32 &&result) override {
+    account_ttl_ = result;
+  }
+
+  void do_send_result() override {
+    send_result(make_tl_object<td_api::accountTtl>(account_ttl_));
+  }
+
+ public:
+  GetAccountTtlRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+  }
+};
+
+class SetAccountTtlRequest : public RequestOnceActor {
+  int32 account_ttl_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->set_account_ttl(account_ttl_, std::move(promise));
+  }
+
+ public:
+  SetAccountTtlRequest(ActorShared<Td> td, uint64 request_id, int32 account_ttl)
+      : RequestOnceActor(std::move(td), request_id), account_ttl_(account_ttl) {
+  }
+};
+
+class GetActiveSessionsRequest : public RequestActor<tl_object_ptr<td_api::sessions>> {
+  tl_object_ptr<td_api::sessions> sessions_;
+
+  void do_run(Promise<tl_object_ptr<td_api::sessions>> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(sessions_));
+      return;
+    }
+
+    td->contacts_manager_->get_active_sessions(std::move(promise));
+  }
+
+  void do_set_result(tl_object_ptr<td_api::sessions> &&result) override {
+    sessions_ = std::move(result);
+  }
+
+  void do_send_result() override {
+    CHECK(sessions_ != nullptr);
+    send_result(std::move(sessions_));
+  }
+
+ public:
+  GetActiveSessionsRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+  }
+};
+
+class TerminateSessionRequest : public RequestOnceActor {
+  int64 session_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->terminate_session(session_id_, std::move(promise));
+  }
+
+ public:
+  TerminateSessionRequest(ActorShared<Td> td, uint64 request_id, int64 session_id)
+      : RequestOnceActor(std::move(td), request_id), session_id_(session_id) {
+  }
+};
+
+class TerminateAllOtherSessionsRequest : public RequestOnceActor {
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->terminate_all_other_sessions(std::move(promise));
+  }
+
+ public:
+  TerminateAllOtherSessionsRequest(ActorShared<Td> td, uint64 request_id)
+      : RequestOnceActor(std::move(td), request_id) {
+  }
+};
+
+class GetConnectedWebsitesRequest : public RequestActor<tl_object_ptr<td_api::connectedWebsites>> {
+  tl_object_ptr<td_api::connectedWebsites> connected_websites_;
+
+  void do_run(Promise<tl_object_ptr<td_api::connectedWebsites>> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(connected_websites_));
+      return;
+    }
+
+    td->contacts_manager_->get_connected_websites(std::move(promise));
+  }
+
+  void do_set_result(tl_object_ptr<td_api::connectedWebsites> &&result) override {
+    connected_websites_ = std::move(result);
+  }
+
+  void do_send_result() override {
+    CHECK(connected_websites_ != nullptr);
+    send_result(std::move(connected_websites_));
+  }
+
+ public:
+  GetConnectedWebsitesRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+  }
+};
+
+class DisconnectWebsiteRequest : public RequestOnceActor {
+  int64 website_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->disconnect_website(website_id_, std::move(promise));
+  }
+
+ public:
+  DisconnectWebsiteRequest(ActorShared<Td> td, uint64 request_id, int64 website_id)
+      : RequestOnceActor(std::move(td), request_id), website_id_(website_id) {
+  }
+};
+
+class DisconnectAllWebsitesRequest : public RequestOnceActor {
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->disconnect_all_websites(std::move(promise));
+  }
+
+ public:
+  DisconnectAllWebsitesRequest(ActorShared<Td> td, uint64 request_id) : RequestOnceActor(std::move(td), request_id) {
+  }
+};
+
+class GetMeRequest : public RequestActor<> {
+  UserId user_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    user_id_ = td->contacts_manager_->get_me(std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->contacts_manager_->get_user_object(user_id_));
+  }
+
+ public:
+  GetMeRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+  }
+};
+
+class GetUserRequest : public RequestActor<> {
+  UserId user_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->get_user(user_id_, get_tries(), std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->contacts_manager_->get_user_object(user_id_));
+  }
+
+ public:
+  GetUserRequest(ActorShared<Td> td, uint64 request_id, int32 user_id)
+      : RequestActor(std::move(td), request_id), user_id_(user_id) {
+    set_tries(3);
+  }
+};
+
+class GetUserFullInfoRequest : public RequestActor<> {
+  UserId user_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->get_user_full(user_id_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->contacts_manager_->get_user_full_info_object(user_id_));
+  }
+
+ public:
+  GetUserFullInfoRequest(ActorShared<Td> td, uint64 request_id, int32 user_id)
+      : RequestActor(std::move(td), request_id), user_id_(user_id) {
+  }
+};
+
+class GetGroupRequest : public RequestActor<> {
+  ChatId chat_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->get_chat(chat_id_, get_tries(), std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->contacts_manager_->get_basic_group_object(chat_id_));
+  }
+
+ public:
+  GetGroupRequest(ActorShared<Td> td, uint64 request_id, int32 chat_id)
+      : RequestActor(std::move(td), request_id), chat_id_(chat_id) {
+    set_tries(3);
+  }
+};
+
+class GetGroupFullInfoRequest : public RequestActor<> {
+  ChatId chat_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->get_chat_full(chat_id_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->contacts_manager_->get_basic_group_full_info_object(chat_id_));
+  }
+
+ public:
+  GetGroupFullInfoRequest(ActorShared<Td> td, uint64 request_id, int32 chat_id)
+      : RequestActor(std::move(td), request_id), chat_id_(chat_id) {
+  }
+};
+
+class GetSupergroupRequest : public RequestActor<> {
+  ChannelId channel_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->get_channel(channel_id_, get_tries(), std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->contacts_manager_->get_supergroup_object(channel_id_));
+  }
+
+ public:
+  GetSupergroupRequest(ActorShared<Td> td, uint64 request_id, int32 channel_id)
+      : RequestActor(std::move(td), request_id), channel_id_(channel_id) {
+    set_tries(3);
+  }
+};
+
+class GetSupergroupFullInfoRequest : public RequestActor<> {
+  ChannelId channel_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->get_channel_full(channel_id_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->contacts_manager_->get_channel_full_info_object(channel_id_));
+  }
+
+ public:
+  GetSupergroupFullInfoRequest(ActorShared<Td> td, uint64 request_id, int32 channel_id)
+      : RequestActor(std::move(td), request_id), channel_id_(channel_id) {
+  }
+};
+
+class GetSecretChatRequest : public RequestActor<> {
+  SecretChatId secret_chat_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->get_secret_chat(secret_chat_id_, get_tries() < 2, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->contacts_manager_->get_secret_chat_object(secret_chat_id_));
+  }
+
+ public:
+  GetSecretChatRequest(ActorShared<Td> td, uint64 request_id, int32 secret_chat_id)
+      : RequestActor(std::move(td), request_id), secret_chat_id_(secret_chat_id) {
+  }
+};
+
+class GetChatRequest : public RequestActor<> {
+  DialogId dialog_id_;
+
+  bool dialog_found_ = false;
+
+  void do_run(Promise<Unit> &&promise) override {
+    dialog_found_ = td->messages_manager_->load_dialog(dialog_id_, get_tries(), std::move(promise));
+  }
+
+  void do_send_result() override {
+    if (!dialog_found_) {
+      send_error(Status::Error(400, "Chat is not accessible"));
+    } else {
+      send_result(td->messages_manager_->get_chat_object(dialog_id_));
+    }
+  }
+
+ public:
+  GetChatRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id)
+      : RequestActor(std::move(td), request_id), dialog_id_(dialog_id) {
+    set_tries(3);
+  }
+};
+
+class GetChatsRequest : public RequestActor<> {
+  DialogDate offset_;
+  int32 limit_;
+
+  vector<DialogId> dialog_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    dialog_ids_ = td->messages_manager_->get_dialogs(offset_, limit_, get_tries() < 2, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(MessagesManager::get_chats_object(dialog_ids_));
+  }
+
+ public:
+  GetChatsRequest(ActorShared<Td> td, uint64 request_id, int64 offset_order, int64 offset_dialog_id, int32 limit)
+      : RequestActor(std::move(td), request_id), offset_(offset_order, DialogId(offset_dialog_id)), limit_(limit) {
+    // 1 for database + 1 for server request + 1 for server request at the end + 1 for return + 1 just in case
+    set_tries(5);
+  }
+};
+
+class SearchPublicChatRequest : public RequestActor<> {
+  string username_;
+
+  DialogId dialog_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    dialog_id_ = td->messages_manager_->search_public_dialog(username_, get_tries() < 3, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_chat_object(dialog_id_));
+  }
+
+ public:
+  SearchPublicChatRequest(ActorShared<Td> td, uint64 request_id, string username)
+      : RequestActor(std::move(td), request_id), username_(std::move(username)) {
+    set_tries(3);
+  }
+};
+
+class SearchPublicChatsRequest : public RequestActor<> {
+  string query_;
+
+  vector<DialogId> dialog_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    dialog_ids_ = td->messages_manager_->search_public_dialogs(query_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(MessagesManager::get_chats_object(dialog_ids_));
+  }
+
+ public:
+  SearchPublicChatsRequest(ActorShared<Td> td, uint64 request_id, string query)
+      : RequestActor(std::move(td), request_id), query_(std::move(query)) {
+  }
+};
+
+class SearchChatsRequest : public RequestActor<> {
+  string query_;
+  int32 limit_;
+
+  vector<DialogId> dialog_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    dialog_ids_ = td->messages_manager_->search_dialogs(query_, limit_, std::move(promise)).second;
+  }
+
+  void do_send_result() override {
+    send_result(MessagesManager::get_chats_object(dialog_ids_));
+  }
+
+ public:
+  SearchChatsRequest(ActorShared<Td> td, uint64 request_id, string query, int32 limit)
+      : RequestActor(std::move(td), request_id), query_(std::move(query)), limit_(limit) {
+  }
+};
+
+class SearchChatsOnServerRequest : public RequestActor<> {
+  string query_;
+  int32 limit_;
+
+  vector<DialogId> dialog_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    dialog_ids_ = td->messages_manager_->search_dialogs_on_server(query_, limit_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(MessagesManager::get_chats_object(dialog_ids_));
+  }
+
+ public:
+  SearchChatsOnServerRequest(ActorShared<Td> td, uint64 request_id, string query, int32 limit)
+      : RequestActor(std::move(td), request_id), query_(std::move(query)), limit_(limit) {
+  }
+};
+
+class GetGroupsInCommonRequest : public RequestActor<> {
+  UserId user_id_;
+  DialogId offset_dialog_id_;
+  int32 limit_;
+
+  vector<DialogId> dialog_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    dialog_ids_ = td->messages_manager_->get_common_dialogs(user_id_, offset_dialog_id_, limit_, get_tries() < 2,
+                                                            std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(MessagesManager::get_chats_object(dialog_ids_));
+  }
+
+ public:
+  GetGroupsInCommonRequest(ActorShared<Td> td, uint64 request_id, int32 user_id, int64 offset_dialog_id, int32 limit)
+      : RequestActor(std::move(td), request_id), user_id_(user_id), offset_dialog_id_(offset_dialog_id), limit_(limit) {
+  }
+};
+
+class CheckChatUsernameRequest : public RequestActor<CheckDialogUsernameResult> {
+  DialogId dialog_id_;
+  string username_;
+
+  CheckDialogUsernameResult result_ = CheckDialogUsernameResult::Ok;
+
+  void do_run(Promise<CheckDialogUsernameResult> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(result_));
+      return;
+    }
+
+    td->contacts_manager_->check_dialog_username(dialog_id_, username_, std::move(promise));
+  }
+
+  void do_set_result(CheckDialogUsernameResult &&result) override {
+    result_ = std::move(result);
+  }
+
+  void do_send_result() override {
+    send_result(ContactsManager::get_check_chat_username_result_object(result_));
+  }
+
+ public:
+  CheckChatUsernameRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, string username)
+      : RequestActor(std::move(td), request_id), dialog_id_(dialog_id), username_(std::move(username)) {
+  }
+};
+
+class GetCreatedPublicChatsRequest : public RequestActor<> {
+  vector<DialogId> dialog_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    dialog_ids_ = td->contacts_manager_->get_created_public_dialogs(std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(MessagesManager::get_chats_object(dialog_ids_));
+  }
+
+ public:
+  GetCreatedPublicChatsRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+  }
+};
+
+class GetMessageRequest : public RequestOnceActor {
+  FullMessageId full_message_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->get_message(full_message_id_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_message_object(full_message_id_));
+  }
+
+ public:
+  GetMessageRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int64 message_id)
+      : RequestOnceActor(std::move(td), request_id), full_message_id_(DialogId(dialog_id), MessageId(message_id)) {
+  }
+};
+
+class GetRepliedMessageRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+  MessageId message_id_;
+
+  MessageId replied_message_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    replied_message_id_ =
+        td->messages_manager_->get_replied_message(dialog_id_, message_id_, get_tries() < 3, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_message_object({dialog_id_, replied_message_id_}));
+  }
+
+ public:
+  GetRepliedMessageRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int64 message_id)
+      : RequestOnceActor(std::move(td), request_id), dialog_id_(dialog_id), message_id_(message_id) {
+    set_tries(3);
+  }
+};
+
+class GetChatPinnedMessageRequest : public RequestActor<MessageId> {
+  DialogId dialog_id_;
+
+  MessageId pinned_message_id_;
+
+  void do_run(Promise<MessageId> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(pinned_message_id_));
+      return;
+    }
+
+    td->messages_manager_->get_dialog_pinned_message(dialog_id_, std::move(promise));
+  }
+
+  void do_set_result(MessageId &&result) override {
+    pinned_message_id_ = result;
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_message_object({dialog_id_, pinned_message_id_}));
+  }
+
+ public:
+  GetChatPinnedMessageRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id)
+      : RequestActor(std::move(td), request_id), dialog_id_(dialog_id) {
+  }
+};
+
+class GetMessagesRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+  vector<MessageId> message_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->get_messages(dialog_id_, message_ids_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_messages_object(-1, dialog_id_, message_ids_));
+  }
+
+ public:
+  GetMessagesRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, const vector<int64> &message_ids)
+      : RequestOnceActor(std::move(td), request_id)
+      , dialog_id_(dialog_id)
+      , message_ids_(MessagesManager::get_message_ids(message_ids)) {
+  }
+};
+
+class GetPublicMessageLinkRequest : public RequestActor<> {
+  FullMessageId full_message_id_;
+  bool for_group_;
+
+  string link_;
+  string html_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    std::tie(link_, html_) =
+        td->messages_manager_->get_public_message_link(full_message_id_, for_group_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(make_tl_object<td_api::publicMessageLink>(link_, html_));
+  }
+
+ public:
+  GetPublicMessageLinkRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int64 message_id, bool for_group)
+      : RequestActor(std::move(td), request_id)
+      , full_message_id_(DialogId(dialog_id), MessageId(message_id))
+      , for_group_(for_group) {
+  }
+};
+
+class EditMessageTextRequest : public RequestOnceActor {
+  FullMessageId full_message_id_;
+  tl_object_ptr<td_api::ReplyMarkup> reply_markup_;
+  tl_object_ptr<td_api::InputMessageContent> input_message_content_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->edit_message_text(full_message_id_, std::move(reply_markup_),
+                                             std::move(input_message_content_), std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_message_object(full_message_id_));
+  }
+
+ public:
+  EditMessageTextRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int64 message_id,
+                         tl_object_ptr<td_api::ReplyMarkup> reply_markup,
+                         tl_object_ptr<td_api::InputMessageContent> input_message_content)
+      : RequestOnceActor(std::move(td), request_id)
+      , full_message_id_(DialogId(dialog_id), MessageId(message_id))
+      , reply_markup_(std::move(reply_markup))
+      , input_message_content_(std::move(input_message_content)) {
+  }
+};
+
+class EditMessageLiveLocationRequest : public RequestOnceActor {
+  FullMessageId full_message_id_;
+  tl_object_ptr<td_api::ReplyMarkup> reply_markup_;
+  tl_object_ptr<td_api::location> location_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->edit_message_live_location(full_message_id_, std::move(reply_markup_), std::move(location_),
+                                                      std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_message_object(full_message_id_));
+  }
+
+ public:
+  EditMessageLiveLocationRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int64 message_id,
+                                 tl_object_ptr<td_api::ReplyMarkup> reply_markup,
+                                 tl_object_ptr<td_api::location> location)
+      : RequestOnceActor(std::move(td), request_id)
+      , full_message_id_(DialogId(dialog_id), MessageId(message_id))
+      , reply_markup_(std::move(reply_markup))
+      , location_(std::move(location)) {
+  }
+};
+
+class EditMessageCaptionRequest : public RequestOnceActor {
+  FullMessageId full_message_id_;
+  tl_object_ptr<td_api::ReplyMarkup> reply_markup_;
+  tl_object_ptr<td_api::formattedText> caption_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->edit_message_caption(full_message_id_, std::move(reply_markup_), std::move(caption_),
+                                                std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_message_object(full_message_id_));
+  }
+
+ public:
+  EditMessageCaptionRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int64 message_id,
+                            tl_object_ptr<td_api::ReplyMarkup> reply_markup,
+                            tl_object_ptr<td_api::formattedText> caption)
+      : RequestOnceActor(std::move(td), request_id)
+      , full_message_id_(DialogId(dialog_id), MessageId(message_id))
+      , reply_markup_(std::move(reply_markup))
+      , caption_(std::move(caption)) {
+  }
+};
+
+class EditMessageReplyMarkupRequest : public RequestOnceActor {
+  FullMessageId full_message_id_;
+  tl_object_ptr<td_api::ReplyMarkup> reply_markup_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->edit_message_reply_markup(full_message_id_, std::move(reply_markup_), std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_message_object(full_message_id_));
+  }
+
+ public:
+  EditMessageReplyMarkupRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int64 message_id,
+                                tl_object_ptr<td_api::ReplyMarkup> reply_markup)
+      : RequestOnceActor(std::move(td), request_id)
+      , full_message_id_(DialogId(dialog_id), MessageId(message_id))
+      , reply_markup_(std::move(reply_markup)) {
+  }
+};
+
+class EditInlineMessageTextRequest : public RequestOnceActor {
+  string inline_message_id_;
+  tl_object_ptr<td_api::ReplyMarkup> reply_markup_;
+  tl_object_ptr<td_api::InputMessageContent> input_message_content_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->edit_inline_message_text(inline_message_id_, std::move(reply_markup_),
+                                                    std::move(input_message_content_), std::move(promise));
+  }
+
+ public:
+  EditInlineMessageTextRequest(ActorShared<Td> td, uint64 request_id, string inline_message_id,
+                               tl_object_ptr<td_api::ReplyMarkup> reply_markup,
+                               tl_object_ptr<td_api::InputMessageContent> input_message_content)
+      : RequestOnceActor(std::move(td), request_id)
+      , inline_message_id_(std::move(inline_message_id))
+      , reply_markup_(std::move(reply_markup))
+      , input_message_content_(std::move(input_message_content)) {
+  }
+};
+
+class EditInlineMessageLiveLocationRequest : public RequestOnceActor {
+  string inline_message_id_;
+  tl_object_ptr<td_api::ReplyMarkup> reply_markup_;
+  tl_object_ptr<td_api::location> location_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->edit_inline_message_live_location(inline_message_id_, std::move(reply_markup_),
+                                                             std::move(location_), std::move(promise));
+  }
+
+ public:
+  EditInlineMessageLiveLocationRequest(ActorShared<Td> td, uint64 request_id, string inline_message_id,
+                                       tl_object_ptr<td_api::ReplyMarkup> reply_markup,
+                                       tl_object_ptr<td_api::location> location)
+      : RequestOnceActor(std::move(td), request_id)
+      , inline_message_id_(std::move(inline_message_id))
+      , reply_markup_(std::move(reply_markup))
+      , location_(std::move(location)) {
+  }
+};
+
+class EditInlineMessageCaptionRequest : public RequestOnceActor {
+  string inline_message_id_;
+  tl_object_ptr<td_api::ReplyMarkup> reply_markup_;
+  tl_object_ptr<td_api::formattedText> caption_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->edit_inline_message_caption(inline_message_id_, std::move(reply_markup_),
+                                                       std::move(caption_), std::move(promise));
+  }
+
+ public:
+  EditInlineMessageCaptionRequest(ActorShared<Td> td, uint64 request_id, string inline_message_id,
+                                  tl_object_ptr<td_api::ReplyMarkup> reply_markup,
+                                  tl_object_ptr<td_api::formattedText> caption)
+      : RequestOnceActor(std::move(td), request_id)
+      , inline_message_id_(std::move(inline_message_id))
+      , reply_markup_(std::move(reply_markup))
+      , caption_(std::move(caption)) {
+  }
+};
+
+class EditInlineMessageReplyMarkupRequest : public RequestOnceActor {
+  string inline_message_id_;
+  tl_object_ptr<td_api::ReplyMarkup> reply_markup_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->edit_inline_message_reply_markup(inline_message_id_, std::move(reply_markup_),
+                                                            std::move(promise));
+  }
+
+ public:
+  EditInlineMessageReplyMarkupRequest(ActorShared<Td> td, uint64 request_id, string inline_message_id,
+                                      tl_object_ptr<td_api::ReplyMarkup> reply_markup)
+      : RequestOnceActor(std::move(td), request_id)
+      , inline_message_id_(std::move(inline_message_id))
+      , reply_markup_(std::move(reply_markup)) {
+  }
+};
+
+class SetGameScoreRequest : public RequestOnceActor {
+  FullMessageId full_message_id_;
+  bool edit_message_;
+  UserId user_id_;
+  int32 score_;
+  bool force_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->set_game_score(full_message_id_, edit_message_, user_id_, score_, force_,
+                                          std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_message_object(full_message_id_));
+  }
+
+ public:
+  SetGameScoreRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int64 message_id, bool edit_message,
+                      int32 user_id, int32 score, bool force)
+      : RequestOnceActor(std::move(td), request_id)
+      , full_message_id_(DialogId(dialog_id), MessageId(message_id))
+      , edit_message_(edit_message)
+      , user_id_(user_id)
+      , score_(score)
+      , force_(force) {
+  }
+};
+
+class SetInlineGameScoreRequest : public RequestOnceActor {
+  string inline_message_id_;
+  bool edit_message_;
+  UserId user_id_;
+  int32 score_;
+  bool force_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->set_inline_game_score(inline_message_id_, edit_message_, user_id_, score_, force_,
+                                                 std::move(promise));
+  }
+
+ public:
+  SetInlineGameScoreRequest(ActorShared<Td> td, uint64 request_id, string inline_message_id, bool edit_message,
+                            int32 user_id, int32 score, bool force)
+      : RequestOnceActor(std::move(td), request_id)
+      , inline_message_id_(std::move(inline_message_id))
+      , edit_message_(edit_message)
+      , user_id_(user_id)
+      , score_(score)
+      , force_(force) {
+  }
+};
+
+class GetGameHighScoresRequest : public RequestOnceActor {
+  FullMessageId full_message_id_;
+  UserId user_id_;
+
+  int64 random_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    random_id_ = td->messages_manager_->get_game_high_scores(full_message_id_, user_id_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    CHECK(random_id_ != 0);
+    send_result(td->messages_manager_->get_game_high_scores_object(random_id_));
+  }
+
+ public:
+  GetGameHighScoresRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int64 message_id, int32 user_id)
+      : RequestOnceActor(std::move(td), request_id)
+      , full_message_id_(DialogId(dialog_id), MessageId(message_id))
+      , user_id_(user_id)
+      , random_id_(0) {
+  }
+};
+
+class GetInlineGameHighScoresRequest : public RequestOnceActor {
+  string inline_message_id_;
+  UserId user_id_;
+
+  int64 random_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    random_id_ = td->messages_manager_->get_inline_game_high_scores(inline_message_id_, user_id_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    CHECK(random_id_ != 0);
+    send_result(td->messages_manager_->get_game_high_scores_object(random_id_));
+  }
+
+ public:
+  GetInlineGameHighScoresRequest(ActorShared<Td> td, uint64 request_id, string inline_message_id, int32 user_id)
+      : RequestOnceActor(std::move(td), request_id)
+      , inline_message_id_(std::move(inline_message_id))
+      , user_id_(user_id)
+      , random_id_(0) {
+  }
+};
+
+class SendChatActionRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+  tl_object_ptr<td_api::ChatAction> action_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->send_dialog_action(dialog_id_, action_, std::move(promise));
+  }
+
+ public:
+  SendChatActionRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id,
+                        tl_object_ptr<td_api::ChatAction> &&action)
+      : RequestOnceActor(std::move(td), request_id), dialog_id_(dialog_id), action_(std::move(action)) {
+  }
+};
+
+class GetChatHistoryRequest : public RequestActor<> {
+  DialogId dialog_id_;
+  MessageId from_message_id_;
+  int32 offset_;
+  int32 limit_;
+  bool only_local_;
+
+  tl_object_ptr<td_api::messages> messages_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    messages_ = td->messages_manager_->get_dialog_history(dialog_id_, from_message_id_, offset_, limit_,
+                                                          get_tries() - 1, only_local_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(std::move(messages_));
+  }
+
+ public:
+  GetChatHistoryRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int64 from_message_id, int32 offset,
+                        int32 limit, bool only_local)
+      : RequestActor(std::move(td), request_id)
+      , dialog_id_(dialog_id)
+      , from_message_id_(from_message_id)
+      , offset_(offset)
+      , limit_(limit)
+      , only_local_(only_local) {
+    if (!only_local_) {
+      set_tries(4);
+    }
+  }
+};
+
+class DeleteChatHistoryRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+  bool remove_from_chat_list_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->delete_dialog_history(dialog_id_, remove_from_chat_list_, std::move(promise));
+  }
+
+ public:
+  DeleteChatHistoryRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, bool remove_from_chat_list)
+      : RequestOnceActor(std::move(td), request_id)
+      , dialog_id_(dialog_id)
+      , remove_from_chat_list_(remove_from_chat_list) {
+  }
+};
+
+class SearchChatMessagesRequest : public RequestActor<> {
+  DialogId dialog_id_;
+  string query_;
+  UserId sender_user_id_;
+  MessageId from_message_id_;
+  int32 offset_;
+  int32 limit_;
+  tl_object_ptr<td_api::SearchMessagesFilter> filter_;
+  int64 random_id_;
+
+  std::pair<int32, vector<MessageId>> messages_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    messages_ = td->messages_manager_->search_dialog_messages(dialog_id_, query_, sender_user_id_, from_message_id_,
+                                                              offset_, limit_, filter_, random_id_, get_tries() == 3,
+                                                              std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_messages_object(messages_.first, dialog_id_, messages_.second));
+  }
+
+  void do_send_error(Status &&status) override {
+    if (status.message() == "SEARCH_QUERY_EMPTY") {
+      messages_.first = 0;
+      messages_.second.clear();
+      return do_send_result();
+    }
+    send_error(std::move(status));
+  }
+
+ public:
+  SearchChatMessagesRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, string query, int32 user_id,
+                            int64 from_message_id, int32 offset, int32 limit,
+                            tl_object_ptr<td_api::SearchMessagesFilter> filter)
+      : RequestActor(std::move(td), request_id)
+      , dialog_id_(dialog_id)
+      , query_(std::move(query))
+      , sender_user_id_(user_id)
+      , from_message_id_(from_message_id)
+      , offset_(offset)
+      , limit_(limit)
+      , filter_(std::move(filter))
+      , random_id_(0) {
+    set_tries(3);
+  }
+};
+
+class OfflineSearchMessagesRequest : public RequestActor<> {
+  DialogId dialog_id_;
+  string query_;
+  int64 from_search_id_;
+  int32 limit_;
+  tl_object_ptr<td_api::SearchMessagesFilter> filter_;
+  int64 random_id_;
+
+  std::pair<int64, vector<FullMessageId>> messages_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    messages_ = td->messages_manager_->offline_search_messages(dialog_id_, query_, from_search_id_, limit_, filter_,
+                                                               random_id_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    vector<tl_object_ptr<td_api::message>> result;
+    result.reserve(messages_.second.size());
+    for (auto full_message_id : messages_.second) {
+      result.push_back(td->messages_manager_->get_message_object(full_message_id));
+    }
+
+    send_result(make_tl_object<td_api::foundMessages>(std::move(result), messages_.first));
+  }
+
+ public:
+  OfflineSearchMessagesRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, string query,
+                               int64 from_search_id, int32 limit, tl_object_ptr<td_api::SearchMessagesFilter> filter)
+      : RequestActor(std::move(td), request_id)
+      , dialog_id_(dialog_id)
+      , query_(std::move(query))
+      , from_search_id_(from_search_id)
+      , limit_(limit)
+      , filter_(std::move(filter))
+      , random_id_(0) {
+  }
+};
+
+class SearchMessagesRequest : public RequestActor<> {
+  string query_;
+  int32 offset_date_;
+  DialogId offset_dialog_id_;
+  MessageId offset_message_id_;
+  int32 limit_;
+  int64 random_id_;
+
+  std::pair<int32, vector<FullMessageId>> messages_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    messages_ = td->messages_manager_->search_messages(query_, offset_date_, offset_dialog_id_, offset_message_id_,
+                                                       limit_, random_id_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_messages_object(messages_.first, messages_.second));
+  }
+
+  void do_send_error(Status &&status) override {
+    if (status.message() == "SEARCH_QUERY_EMPTY") {
+      messages_.first = 0;
+      messages_.second.clear();
+      return do_send_result();
+    }
+    send_error(std::move(status));
+  }
+
+ public:
+  SearchMessagesRequest(ActorShared<Td> td, uint64 request_id, string query, int32 offset_date, int64 offset_dialog_id,
+                        int64 offset_message_id, int32 limit)
+      : RequestActor(std::move(td), request_id)
+      , query_(std::move(query))
+      , offset_date_(offset_date)
+      , offset_dialog_id_(offset_dialog_id)
+      , offset_message_id_(offset_message_id)
+      , limit_(limit)
+      , random_id_(0) {
+  }
+};
+
+class SearchCallMessagesRequest : public RequestActor<> {
+  MessageId from_message_id_;
+  int32 limit_;
+  bool only_missed_;
+  int64 random_id_;
+
+  std::pair<int32, vector<FullMessageId>> messages_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    messages_ = td->messages_manager_->search_call_messages(from_message_id_, limit_, only_missed_, random_id_,
+                                                            get_tries() == 3, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_messages_object(messages_.first, messages_.second));
+  }
+
+ public:
+  SearchCallMessagesRequest(ActorShared<Td> td, uint64 request_id, int64 from_message_id, int32 limit, bool only_missed)
+      : RequestActor(std::move(td), request_id)
+      , from_message_id_(from_message_id)
+      , limit_(limit)
+      , only_missed_(only_missed)
+      , random_id_(0) {
+    set_tries(3);
+  }
+};
+
+class SearchChatRecentLocationMessagesRequest : public RequestActor<> {
+  DialogId dialog_id_;
+  int32 limit_;
+  int64 random_id_;
+
+  std::pair<int32, vector<MessageId>> messages_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    messages_ = td->messages_manager_->search_dialog_recent_location_messages(dialog_id_, limit_, random_id_,
+                                                                              std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_messages_object(messages_.first, dialog_id_, messages_.second));
+  }
+
+ public:
+  SearchChatRecentLocationMessagesRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int32 limit)
+      : RequestActor(std::move(td), request_id), dialog_id_(dialog_id), limit_(limit), random_id_(0) {
+  }
+};
+
+class GetActiveLiveLocationMessagesRequest : public RequestActor<> {
+  vector<FullMessageId> full_message_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    full_message_ids_ = td->messages_manager_->get_active_live_location_messages(std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_messages_object(-1, full_message_ids_));
+  }
+
+ public:
+  GetActiveLiveLocationMessagesRequest(ActorShared<Td> td, uint64 request_id)
+      : RequestActor(std::move(td), request_id) {
+  }
+};
+
+class GetChatMessageByDateRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+  int32 date_;
+
+  int64 random_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    random_id_ = td->messages_manager_->get_dialog_message_by_date(dialog_id_, date_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_dialog_message_by_date_object(random_id_));
+  }
+
+ public:
+  GetChatMessageByDateRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int32 date)
+      : RequestOnceActor(std::move(td), request_id), dialog_id_(dialog_id), date_(date), random_id_(0) {
+  }
+};
+
+class DeleteMessagesRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+  vector<MessageId> message_ids_;
+  bool revoke_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->delete_messages(dialog_id_, message_ids_, revoke_, std::move(promise));
+  }
+
+ public:
+  DeleteMessagesRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, vector<int64> message_ids, bool revoke)
+      : RequestOnceActor(std::move(td), request_id)
+      , dialog_id_(dialog_id)
+      , message_ids_(MessagesManager::get_message_ids(message_ids))
+      , revoke_(revoke) {
+  }
+};
+
+class DeleteChatMessagesFromUserRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+  UserId user_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->delete_dialog_messages_from_user(dialog_id_, user_id_, std::move(promise));
+  }
+
+ public:
+  DeleteChatMessagesFromUserRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int32 user_id)
+      : RequestOnceActor(std::move(td), request_id), dialog_id_(dialog_id), user_id_(user_id) {
+  }
+};
+
+class ReadAllChatMentionsRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->read_all_dialog_mentions(dialog_id_, std::move(promise));
+  }
+
+ public:
+  ReadAllChatMentionsRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id)
+      : RequestOnceActor(std::move(td), request_id), dialog_id_(dialog_id) {
+  }
+};
+
+class GetWebPagePreviewRequest : public RequestOnceActor {
+  td_api::object_ptr<td_api::formattedText> text_;
+
+  int64 request_id_ = 0;
+
+  void do_run(Promise<Unit> &&promise) override {
+    request_id_ = td->web_pages_manager_->get_web_page_preview(std::move(text_), std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->web_pages_manager_->get_web_page_preview_result(request_id_));
+  }
+
+ public:
+  GetWebPagePreviewRequest(ActorShared<Td> td, uint64 request_id, td_api::object_ptr<td_api::formattedText> text)
+      : RequestOnceActor(std::move(td), request_id), text_(std::move(text)) {
+  }
+};
+
+class GetWebPageInstantViewRequest : public RequestActor<> {
+  string url_;
+  bool force_full_;
+
+  WebPageId web_page_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    web_page_id_ = td->web_pages_manager_->get_web_page_instant_view(url_, force_full_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->web_pages_manager_->get_web_page_instant_view_object(web_page_id_));
+  }
+
+ public:
+  GetWebPageInstantViewRequest(ActorShared<Td> td, uint64 request_id, string url, bool force_full)
+      : RequestActor(std::move(td), request_id), url_(std::move(url)), force_full_(force_full) {
+    set_tries(3);
+  }
+};
+
+class CreateChatRequest : public RequestActor<> {
+  DialogId dialog_id_;
+  bool force_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->create_dialog(dialog_id_, force_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->messages_manager_->get_chat_object(dialog_id_));
+  }
+
+ public:
+  CreateChatRequest(ActorShared<Td> td, uint64 request_id, DialogId dialog_id, bool force)
+      : RequestActor<>(std::move(td), request_id), dialog_id_(dialog_id), force_(force) {
+  }
+};
+
+class CreateNewGroupChatRequest : public RequestActor<> {
+  vector<UserId> user_ids_;
+  string title_;
+  int64 random_id_;
+
+  DialogId dialog_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    dialog_id_ = td->messages_manager_->create_new_group_chat(user_ids_, title_, random_id_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    CHECK(dialog_id_.is_valid());
+    send_result(td->messages_manager_->get_chat_object(dialog_id_));
+  }
+
+ public:
+  CreateNewGroupChatRequest(ActorShared<Td> td, uint64 request_id, vector<int32> user_ids, string title)
+      : RequestActor(std::move(td), request_id), title_(std::move(title)), random_id_(0) {
+    for (auto user_id : user_ids) {
+      user_ids_.emplace_back(user_id);
+    }
+  }
+};
+
+class CreateNewSecretChatRequest : public RequestActor<SecretChatId> {
+  UserId user_id_;
+  SecretChatId secret_chat_id_;
+
+  void do_run(Promise<SecretChatId> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(secret_chat_id_));
+      return;
+    }
+    td->messages_manager_->create_new_secret_chat(user_id_, std::move(promise));
+  }
+
+  void do_set_result(SecretChatId &&result) override {
+    secret_chat_id_ = result;
+    LOG(INFO) << "New " << secret_chat_id_ << " created";
+  }
+
+  void do_send_result() override {
+    CHECK(secret_chat_id_.is_valid());
+    // SecretChatActor will send this update by himself.
+    // But since the update may still be on its way, we will update essential fields here.
+    td->contacts_manager_->on_update_secret_chat(
+        secret_chat_id_, 0 /* no access_hash */, user_id_, SecretChatState::Unknown, true /* it is outbound chat */,
+        -1 /* unknown ttl */, 0 /* unknown creation date */, "" /* no key_hash */, 0);
+    DialogId dialog_id(secret_chat_id_);
+    td->messages_manager_->force_create_dialog(dialog_id, "create new secret chat");
+    send_result(td->messages_manager_->get_chat_object(dialog_id));
+  }
+
+ public:
+  CreateNewSecretChatRequest(ActorShared<Td> td, uint64 request_id, int32 user_id)
+      : RequestActor(std::move(td), request_id), user_id_(user_id) {
+  }
+};
+
+class CreateNewSupergroupChatRequest : public RequestActor<> {
+  string title_;
+  bool is_megagroup_;
+  string description_;
+  int64 random_id_;
+
+  DialogId dialog_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    dialog_id_ = td->messages_manager_->create_new_channel_chat(title_, is_megagroup_, description_, random_id_,
+                                                                std::move(promise));
+  }
+
+  void do_send_result() override {
+    CHECK(dialog_id_.is_valid());
+    send_result(td->messages_manager_->get_chat_object(dialog_id_));
+  }
+
+ public:
+  CreateNewSupergroupChatRequest(ActorShared<Td> td, uint64 request_id, string title, bool is_megagroup,
+                                 string description)
+      : RequestActor(std::move(td), request_id)
+      , title_(std::move(title))
+      , is_megagroup_(is_megagroup)
+      , description_(std::move(description))
+      , random_id_(0) {
+  }
+};
+
+class UpgradeGroupChatToSupergroupChatRequest : public RequestActor<> {
+  string title_;
+  DialogId dialog_id_;
+
+  DialogId result_dialog_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    result_dialog_id_ = td->messages_manager_->migrate_dialog_to_megagroup(dialog_id_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    CHECK(result_dialog_id_.is_valid());
+    send_result(td->messages_manager_->get_chat_object(result_dialog_id_));
+  }
+
+ public:
+  UpgradeGroupChatToSupergroupChatRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id)
+      : RequestActor(std::move(td), request_id), dialog_id_(dialog_id) {
+  }
+};
+
+class SetChatPhotoRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+  tl_object_ptr<td_api::InputFile> input_file_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->set_dialog_photo(dialog_id_, input_file_, std::move(promise));
+  }
+
+ public:
+  SetChatPhotoRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id,
+                      tl_object_ptr<td_api::InputFile> &&input_file)
+      : RequestOnceActor(std::move(td), request_id), dialog_id_(dialog_id), input_file_(std::move(input_file)) {
+  }
+};
+
+class SetChatTitleRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+  string title_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->set_dialog_title(dialog_id_, title_, std::move(promise));
+  }
+
+ public:
+  SetChatTitleRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, string &&title)
+      : RequestOnceActor(std::move(td), request_id), dialog_id_(dialog_id), title_(std::move(title)) {
+  }
+};
+
+class AddChatMemberRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+  UserId user_id_;
+  int32 forward_limit_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->add_dialog_participant(dialog_id_, user_id_, forward_limit_, std::move(promise));
+  }
+
+ public:
+  AddChatMemberRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int32 user_id, int32 forward_limit)
+      : RequestOnceActor(std::move(td), request_id)
+      , dialog_id_(dialog_id)
+      , user_id_(user_id)
+      , forward_limit_(forward_limit) {
+  }
+};
+
+class AddChatMembersRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+  vector<UserId> user_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->add_dialog_participants(dialog_id_, user_ids_, std::move(promise));
+  }
+
+ public:
+  AddChatMembersRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, const vector<int32> &user_ids)
+      : RequestOnceActor(std::move(td), request_id), dialog_id_(dialog_id) {
+    for (auto &user_id : user_ids) {
+      user_ids_.emplace_back(user_id);
+    }
+  }
+};
+
+class SetChatMemberStatusRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+  UserId user_id_;
+  tl_object_ptr<td_api::ChatMemberStatus> status_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->set_dialog_participant_status(dialog_id_, user_id_, status_, std::move(promise));
+  }
+
+ public:
+  SetChatMemberStatusRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int32 user_id,
+                             tl_object_ptr<td_api::ChatMemberStatus> &&status)
+      : RequestOnceActor(std::move(td), request_id)
+      , dialog_id_(dialog_id)
+      , user_id_(user_id)
+      , status_(std::move(status)) {
+  }
+};
+
+class GetChatMemberRequest : public RequestActor<> {
+  DialogId dialog_id_;
+  UserId user_id_;
+  int64 random_id_;
+
+  DialogParticipant dialog_participant_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    dialog_participant_ = td->messages_manager_->get_dialog_participant(dialog_id_, user_id_, random_id_,
+                                                                        get_tries() < 3, std::move(promise));
+  }
+
+  void do_send_result() override {
+    if (!td->contacts_manager_->have_user(user_id_)) {
+      return send_error(Status::Error(3, "User not found"));
+    }
+    send_result(td->contacts_manager_->get_chat_member_object(dialog_participant_));
+  }
+
+  void do_send_error(Status &&status) override {
+    send_error(std::move(status));
+  }
+
+ public:
+  GetChatMemberRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int32 user_id)
+      : RequestActor(std::move(td), request_id), dialog_id_(dialog_id), user_id_(user_id), random_id_(0) {
+    set_tries(3);
+  }
+};
+
+class SearchChatMembersRequest : public RequestActor<> {
+  DialogId dialog_id_;
+  string query_;
+  int32 limit_;
+  int64 random_id_ = 0;
+
+  std::pair<int32, vector<DialogParticipant>> participants_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    participants_ = td->messages_manager_->search_dialog_participants(dialog_id_, query_, limit_, random_id_,
+                                                                      get_tries() < 3, std::move(promise));
+  }
+
+  void do_send_result() override {
+    // TODO create function get_chat_members_object
+    vector<tl_object_ptr<td_api::chatMember>> result;
+    result.reserve(participants_.second.size());
+    for (auto participant : participants_.second) {
+      result.push_back(td->contacts_manager_->get_chat_member_object(participant));
+    }
+
+    send_result(make_tl_object<td_api::chatMembers>(participants_.first, std::move(result)));
+  }
+
+ public:
+  SearchChatMembersRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, string &&query, int32 limit)
+      : RequestActor(std::move(td), request_id), dialog_id_(dialog_id), query_(std::move(query)), limit_(limit) {
+    set_tries(3);
+  }
+};
+
+class GetChatAdministratorsRequest : public RequestActor<> {
+  DialogId dialog_id_;
+
+  vector<UserId> user_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    user_ids_ = td->messages_manager_->get_dialog_administrators(dialog_id_, get_tries(), std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->contacts_manager_->get_users_object(-1, user_ids_));
+  }
+
+ public:
+  GetChatAdministratorsRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id)
+      : RequestActor(std::move(td), request_id), dialog_id_(dialog_id) {
+    set_tries(3);
+  }
+};
+
+class GenerateChatInviteLinkRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->export_dialog_invite_link(dialog_id_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(make_tl_object<td_api::chatInviteLink>(td->messages_manager_->get_dialog_invite_link(dialog_id_)));
+  }
+
+ public:
+  GenerateChatInviteLinkRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id)
+      : RequestOnceActor(std::move(td), request_id), dialog_id_(dialog_id) {
+  }
+};
+
+class CheckChatInviteLinkRequest : public RequestActor<> {
+  string invite_link_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->check_dialog_invite_link(invite_link_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    auto result = td->contacts_manager_->get_chat_invite_link_info_object(invite_link_);
+    CHECK(result != nullptr);
+    send_result(std::move(result));
+  }
+
+ public:
+  CheckChatInviteLinkRequest(ActorShared<Td> td, uint64 request_id, string invite_link)
+      : RequestActor(std::move(td), request_id), invite_link_(std::move(invite_link)) {
+  }
+};
+
+class JoinChatByInviteLinkRequest : public RequestActor<DialogId> {
+  string invite_link_;
+
+  DialogId dialog_id_;
+
+  void do_run(Promise<DialogId> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(dialog_id_));
+      return;
+    }
+    td->contacts_manager_->import_dialog_invite_link(invite_link_, std::move(promise));
+  }
+
+  void do_set_result(DialogId &&result) override {
+    dialog_id_ = result;
+  }
+
+  void do_send_result() override {
+    CHECK(dialog_id_.is_valid());
+    td->messages_manager_->force_create_dialog(dialog_id_, "join chat by invite link");
+    send_result(td->messages_manager_->get_chat_object(dialog_id_));
+  }
+
+ public:
+  JoinChatByInviteLinkRequest(ActorShared<Td> td, uint64 request_id, string invite_link)
+      : RequestActor(std::move(td), request_id), invite_link_(std::move(invite_link)) {
+  }
+};
+
+class GetChatEventLogRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+  string query_;
+  int64 from_event_id_;
+  int32 limit_;
+  tl_object_ptr<td_api::chatEventLogFilters> filters_;
+  vector<UserId> user_ids_;
+
+  int64 random_id_ = 0;
+
+  void do_run(Promise<Unit> &&promise) override {
+    random_id_ = td->messages_manager_->get_dialog_event_log(dialog_id_, query_, from_event_id_, limit_, filters_,
+                                                             user_ids_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    CHECK(random_id_ != 0);
+    send_result(td->messages_manager_->get_chat_events_object(random_id_));
+  }
+
+ public:
+  GetChatEventLogRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, string &&query, int64 from_event_id,
+                         int32 limit, tl_object_ptr<td_api::chatEventLogFilters> &&filters, vector<int32> user_ids)
+      : RequestOnceActor(std::move(td), request_id)
+      , dialog_id_(dialog_id)
+      , query_(std::move(query))
+      , from_event_id_(from_event_id)
+      , limit_(limit)
+      , filters_(std::move(filters)) {
+    for (auto user_id : user_ids) {
+      user_ids_.emplace_back(user_id);
+    }
+  }
+};
+
+class GetBlockedUsersRequest : public RequestOnceActor {
+  int32 offset_;
+  int32 limit_;
+
+  int64 random_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    random_id_ = td->contacts_manager_->get_blocked_users(offset_, limit_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->contacts_manager_->get_blocked_users_object(random_id_));
+  }
+
+ public:
+  GetBlockedUsersRequest(ActorShared<Td> td, uint64 request_id, int32 offset, int32 limit)
+      : RequestOnceActor(std::move(td), request_id), offset_(offset), limit_(limit), random_id_(0) {
+  }
+};
+
+class ImportContactsRequest : public RequestActor<> {
+  vector<tl_object_ptr<td_api::contact>> contacts_;
+  int64 random_id_;
+
+  std::pair<vector<UserId>, vector<int32>> imported_contacts_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    imported_contacts_ = td->contacts_manager_->import_contacts(contacts_, random_id_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    CHECK(imported_contacts_.first.size() == contacts_.size());
+    CHECK(imported_contacts_.second.size() == contacts_.size());
+    send_result(make_tl_object<td_api::importedContacts>(transform(imported_contacts_.first,
+                                                                   [this](UserId user_id) {
+                                                                     return td->contacts_manager_->get_user_id_object(
+                                                                         user_id, "ImportContactsRequest");
+                                                                   }),
+                                                         std::move(imported_contacts_.second)));
+  }
+
+ public:
+  ImportContactsRequest(ActorShared<Td> td, uint64 request_id, vector<tl_object_ptr<td_api::contact>> &&contacts)
+      : RequestActor(std::move(td), request_id), contacts_(std::move(contacts)), random_id_(0) {
+    set_tries(3);  // load_contacts + import_contacts
+  }
+};
+
+class SearchContactsRequest : public RequestActor<> {
+  string query_;
+  int32 limit_;
+
+  std::pair<int32, vector<UserId>> user_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    user_ids_ = td->contacts_manager_->search_contacts(query_, limit_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->contacts_manager_->get_users_object(user_ids_.first, user_ids_.second));
+  }
+
+ public:
+  SearchContactsRequest(ActorShared<Td> td, uint64 request_id, string query, int32 limit)
+      : RequestActor(std::move(td), request_id), query_(std::move(query)), limit_(limit) {
+  }
+};
+
+class RemoveContactsRequest : public RequestActor<> {
+  vector<UserId> user_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->remove_contacts(user_ids_, std::move(promise));
+  }
+
+ public:
+  RemoveContactsRequest(ActorShared<Td> td, uint64 request_id, vector<int32> &&user_ids)
+      : RequestActor(std::move(td), request_id) {
+    for (auto user_id : user_ids) {
+      user_ids_.emplace_back(user_id);
+    }
+    set_tries(3);  // load_contacts + delete_contacts
+  }
+};
+
+class GetImportedContactCountRequest : public RequestActor<> {
+  int32 imported_contact_count_ = 0;
+
+  void do_run(Promise<Unit> &&promise) override {
+    imported_contact_count_ = td->contacts_manager_->get_imported_contact_count(std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td_api::make_object<td_api::count>(imported_contact_count_));
+  }
+
+ public:
+  GetImportedContactCountRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+  }
+};
+
+class ChangeImportedContactsRequest : public RequestActor<> {
+  vector<tl_object_ptr<td_api::contact>> contacts_;
+  size_t contacts_size_;
+  int64 random_id_;
+
+  std::pair<vector<UserId>, vector<int32>> imported_contacts_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    imported_contacts_ =
+        td->contacts_manager_->change_imported_contacts(std::move(contacts_), random_id_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    CHECK(imported_contacts_.first.size() == contacts_size_);
+    CHECK(imported_contacts_.second.size() == contacts_size_);
+    send_result(make_tl_object<td_api::importedContacts>(transform(imported_contacts_.first,
+                                                                   [this](UserId user_id) {
+                                                                     return td->contacts_manager_->get_user_id_object(
+                                                                         user_id, "ChangeImportedContactsRequest");
+                                                                   }),
+                                                         std::move(imported_contacts_.second)));
+  }
+
+ public:
+  ChangeImportedContactsRequest(ActorShared<Td> td, uint64 request_id,
+                                vector<tl_object_ptr<td_api::contact>> &&contacts)
+      : RequestActor(std::move(td), request_id)
+      , contacts_(std::move(contacts))
+      , contacts_size_(contacts_.size())
+      , random_id_(0) {
+    set_tries(4);  // load_contacts + load_local_contacts + (import_contacts + delete_contacts)
+  }
+};
+
+class ClearImportedContactsRequest : public RequestActor<> {
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->clear_imported_contacts(std::move(promise));
+  }
+
+ public:
+  ClearImportedContactsRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+    set_tries(3);  // load_contacts + clear
+  }
+};
+
+class GetRecentInlineBotsRequest : public RequestActor<> {
+  vector<UserId> user_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    user_ids_ = td->inline_queries_manager_->get_recent_inline_bots(std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->contacts_manager_->get_users_object(-1, user_ids_));
+  }
+
+ public:
+  GetRecentInlineBotsRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+  }
+};
+
+class SetNameRequest : public RequestOnceActor {
+  string first_name_;
+  string last_name_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->set_name(first_name_, last_name_, std::move(promise));
+  }
+
+ public:
+  SetNameRequest(ActorShared<Td> td, uint64 request_id, string first_name, string last_name)
+      : RequestOnceActor(std::move(td), request_id)
+      , first_name_(std::move(first_name))
+      , last_name_(std::move(last_name)) {
+  }
+};
+
+class SetBioRequest : public RequestOnceActor {
+  string bio_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->set_bio(bio_, std::move(promise));
+  }
+
+ public:
+  SetBioRequest(ActorShared<Td> td, uint64 request_id, string bio)
+      : RequestOnceActor(std::move(td), request_id), bio_(std::move(bio)) {
+  }
+};
+
+class SetUsernameRequest : public RequestOnceActor {
+  string username_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->set_username(username_, std::move(promise));
+  }
+
+ public:
+  SetUsernameRequest(ActorShared<Td> td, uint64 request_id, string username)
+      : RequestOnceActor(std::move(td), request_id), username_(std::move(username)) {
+  }
+};
+
+class SetProfilePhotoRequest : public RequestOnceActor {
+  tl_object_ptr<td_api::InputFile> input_file_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->set_profile_photo(input_file_, std::move(promise));
+  }
+
+ public:
+  SetProfilePhotoRequest(ActorShared<Td> td, uint64 request_id, tl_object_ptr<td_api::InputFile> &&input_file)
+      : RequestOnceActor(std::move(td), request_id), input_file_(std::move(input_file)) {
+  }
+};
+
+class DeleteProfilePhotoRequest : public RequestOnceActor {
+  int64 profile_photo_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->delete_profile_photo(profile_photo_id_, std::move(promise));
+  }
+
+ public:
+  DeleteProfilePhotoRequest(ActorShared<Td> td, uint64 request_id, int64 profile_photo_id)
+      : RequestOnceActor(std::move(td), request_id), profile_photo_id_(profile_photo_id) {
+  }
+};
+
+class ToggleGroupAdministratorsRequest : public RequestOnceActor {
+  ChatId chat_id_;
+  bool everyone_is_administrator_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->toggle_chat_administrators(chat_id_, everyone_is_administrator_, std::move(promise));
+  }
+
+ public:
+  ToggleGroupAdministratorsRequest(ActorShared<Td> td, uint64 request_id, int32 chat_id, bool everyone_is_administrator)
+      : RequestOnceActor(std::move(td), request_id)
+      , chat_id_(chat_id)
+      , everyone_is_administrator_(everyone_is_administrator) {
+  }
+};
+
+class SetSupergroupUsernameRequest : public RequestOnceActor {
+  ChannelId channel_id_;
+  string username_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->set_channel_username(channel_id_, username_, std::move(promise));
+  }
+
+ public:
+  SetSupergroupUsernameRequest(ActorShared<Td> td, uint64 request_id, int32 channel_id, string username)
+      : RequestOnceActor(std::move(td), request_id), channel_id_(channel_id), username_(std::move(username)) {
+  }
+};
+
+class SetSupergroupStickerSetRequest : public RequestOnceActor {
+  ChannelId channel_id_;
+  int64 sticker_set_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->set_channel_sticker_set(channel_id_, sticker_set_id_, std::move(promise));
+  }
+
+ public:
+  SetSupergroupStickerSetRequest(ActorShared<Td> td, uint64 request_id, int32 channel_id, int64 sticker_set_id)
+      : RequestOnceActor(std::move(td), request_id), channel_id_(channel_id), sticker_set_id_(sticker_set_id) {
+  }
+};
+
+class ToggleSupergroupInvitesRequest : public RequestOnceActor {
+  ChannelId channel_id_;
+  bool anyone_can_invite_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->toggle_channel_invites(channel_id_, anyone_can_invite_, std::move(promise));
+  }
+
+ public:
+  ToggleSupergroupInvitesRequest(ActorShared<Td> td, uint64 request_id, int32 channel_id, bool anyone_can_invite)
+      : RequestOnceActor(std::move(td), request_id), channel_id_(channel_id), anyone_can_invite_(anyone_can_invite) {
+  }
+};
+
+class ToggleSupergroupSignMessagesRequest : public RequestOnceActor {
+  ChannelId channel_id_;
+  bool sign_messages_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->toggle_channel_sign_messages(channel_id_, sign_messages_, std::move(promise));
+  }
+
+ public:
+  ToggleSupergroupSignMessagesRequest(ActorShared<Td> td, uint64 request_id, int32 channel_id, bool sign_messages)
+      : RequestOnceActor(std::move(td), request_id), channel_id_(channel_id), sign_messages_(sign_messages) {
+  }
+};
+
+class ToggleSupergroupIsAllHistoryAvailableRequest : public RequestOnceActor {
+  ChannelId channel_id_;
+  bool is_all_history_available_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->toggle_channel_is_all_history_available(channel_id_, is_all_history_available_,
+                                                                   std::move(promise));
+  }
+
+ public:
+  ToggleSupergroupIsAllHistoryAvailableRequest(ActorShared<Td> td, uint64 request_id, int32 channel_id,
+                                               bool is_all_history_available)
+      : RequestOnceActor(std::move(td), request_id)
+      , channel_id_(channel_id)
+      , is_all_history_available_(is_all_history_available) {
+  }
+};
+
+class SetSupergroupDescriptionRequest : public RequestOnceActor {
+  ChannelId channel_id_;
+  string description_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->set_channel_description(channel_id_, description_, std::move(promise));
+  }
+
+ public:
+  SetSupergroupDescriptionRequest(ActorShared<Td> td, uint64 request_id, int32 channel_id, string description)
+      : RequestOnceActor(std::move(td), request_id), channel_id_(channel_id), description_(std::move(description)) {
+  }
+};
+
+class PinSupergroupMessageRequest : public RequestOnceActor {
+  ChannelId channel_id_;
+  MessageId message_id_;
+  bool disable_notification_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->pin_channel_message(channel_id_, message_id_, disable_notification_, std::move(promise));
+  }
+
+ public:
+  PinSupergroupMessageRequest(ActorShared<Td> td, uint64 request_id, int32 channel_id, int64 message_id,
+                              bool disable_notification)
+      : RequestOnceActor(std::move(td), request_id)
+      , channel_id_(channel_id)
+      , message_id_(message_id)
+      , disable_notification_(disable_notification) {
+  }
+};
+
+class UnpinSupergroupMessageRequest : public RequestOnceActor {
+  ChannelId channel_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->unpin_channel_message(channel_id_, std::move(promise));
+  }
+
+ public:
+  UnpinSupergroupMessageRequest(ActorShared<Td> td, uint64 request_id, int32 channel_id)
+      : RequestOnceActor(std::move(td), request_id), channel_id_(channel_id) {
+  }
+};
+
+class ReportSupergroupSpamRequest : public RequestOnceActor {
+  ChannelId channel_id_;
+  UserId user_id_;
+  vector<MessageId> message_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->report_channel_spam(channel_id_, user_id_, message_ids_, std::move(promise));
+  }
+
+ public:
+  ReportSupergroupSpamRequest(ActorShared<Td> td, uint64 request_id, int32 channel_id, int32 user_id,
+                              const vector<int64> &message_ids)
+      : RequestOnceActor(std::move(td), request_id)
+      , channel_id_(channel_id)
+      , user_id_(user_id)
+      , message_ids_(MessagesManager::get_message_ids(message_ids)) {
+  }
+};
+
+class GetSupergroupMembersRequest : public RequestActor<> {
+  ChannelId channel_id_;
+  tl_object_ptr<td_api::SupergroupMembersFilter> filter_;
+  int32 offset_;
+  int32 limit_;
+  int64 random_id_ = 0;
+
+  std::pair<int32, vector<DialogParticipant>> participants_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    participants_ = td->contacts_manager_->get_channel_participants(channel_id_, filter_, offset_, limit_, random_id_,
+                                                                    get_tries() < 3, std::move(promise));
+  }
+
+  void do_send_result() override {
+    // TODO create function get_chat_members_object
+    vector<tl_object_ptr<td_api::chatMember>> result;
+    result.reserve(participants_.second.size());
+    for (auto participant : participants_.second) {
+      result.push_back(td->contacts_manager_->get_chat_member_object(participant));
+    }
+
+    send_result(make_tl_object<td_api::chatMembers>(participants_.first, std::move(result)));
+  }
+
+ public:
+  GetSupergroupMembersRequest(ActorShared<Td> td, uint64 request_id, int32 channel_id,
+                              tl_object_ptr<td_api::SupergroupMembersFilter> &&filter, int32 offset, int32 limit)
+      : RequestActor(std::move(td), request_id)
+      , channel_id_(channel_id)
+      , filter_(std::move(filter))
+      , offset_(offset)
+      , limit_(limit) {
+    set_tries(3);
+  }
+};
+
+class DeleteSupergroupRequest : public RequestOnceActor {
+  ChannelId channel_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->contacts_manager_->delete_channel(channel_id_, std::move(promise));
+  }
+
+ public:
+  DeleteSupergroupRequest(ActorShared<Td> td, uint64 request_id, int32 channel_id)
+      : RequestOnceActor(std::move(td), request_id), channel_id_(channel_id) {
+  }
+};
+
+class GetUserProfilePhotosRequest : public RequestActor<> {
+  UserId user_id_;
+  int32 offset_;
+  int32 limit_;
+  std::pair<int32, vector<const Photo *>> photos;
+
+  void do_run(Promise<Unit> &&promise) override {
+    photos = td->contacts_manager_->get_user_profile_photos(user_id_, offset_, limit_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    // TODO create function get_user_profile_photos_object
+    vector<tl_object_ptr<td_api::photo>> result;
+    result.reserve(photos.second.size());
+    for (auto photo : photos.second) {
+      result.push_back(get_photo_object(td->file_manager_.get(), photo));
+    }
+
+    send_result(make_tl_object<td_api::userProfilePhotos>(photos.first, std::move(result)));
+  }
+
+ public:
+  GetUserProfilePhotosRequest(ActorShared<Td> td, uint64 request_id, int32 user_id, int32 offset, int32 limit)
+      : RequestActor(std::move(td), request_id), user_id_(user_id), offset_(offset), limit_(limit) {
+  }
+};
+
+class GetNotificationSettingsRequest : public RequestActor<> {
+  NotificationSettingsScope scope_;
+
+  const NotificationSettings *notification_settings_ = nullptr;
+
+  void do_run(Promise<Unit> &&promise) override {
+    notification_settings_ = td->messages_manager_->get_notification_settings(scope_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    CHECK(notification_settings_ != nullptr);
+    send_result(td->messages_manager_->get_notification_settings_object(notification_settings_));
+  }
+
+ public:
+  GetNotificationSettingsRequest(ActorShared<Td> td, uint64 request_id, NotificationSettingsScope scope)
+      : RequestActor(std::move(td), request_id), scope_(scope) {
+  }
+};
+
+class GetChatReportSpamStateRequest : public RequestActor<> {
+  DialogId dialog_id_;
+
+  bool can_report_spam_ = false;
+
+  void do_run(Promise<Unit> &&promise) override {
+    can_report_spam_ = td->messages_manager_->get_dialog_report_spam_state(dialog_id_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(make_tl_object<td_api::chatReportSpamState>(can_report_spam_));
+  }
+
+ public:
+  GetChatReportSpamStateRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id)
+      : RequestActor(std::move(td), request_id), dialog_id_(dialog_id) {
+  }
+};
+
+class ChangeChatReportSpamStateRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+  bool is_spam_dialog_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->change_dialog_report_spam_state(dialog_id_, is_spam_dialog_, std::move(promise));
+  }
+
+ public:
+  ChangeChatReportSpamStateRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, bool is_spam_dialog)
+      : RequestOnceActor(std::move(td), request_id), dialog_id_(dialog_id), is_spam_dialog_(is_spam_dialog) {
+  }
+};
+
+class ReportChatRequest : public RequestOnceActor {
+  DialogId dialog_id_;
+  tl_object_ptr<td_api::ChatReportReason> reason_;
+  vector<MessageId> message_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->messages_manager_->report_dialog(dialog_id_, reason_, message_ids_, std::move(promise));
+  }
+
+ public:
+  ReportChatRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id,
+                    tl_object_ptr<td_api::ChatReportReason> reason, const vector<int64> &message_ids)
+      : RequestOnceActor(std::move(td), request_id)
+      , dialog_id_(dialog_id)
+      , reason_(std::move(reason))
+      , message_ids_(MessagesManager::get_message_ids(message_ids)) {
+  }
+};
+
+class GetStickersRequest : public RequestActor<> {
+  string emoji_;
+  int32 limit_;
+
+  vector<FileId> sticker_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    sticker_ids_ = td->stickers_manager_->get_stickers(emoji_, limit_, get_tries() < 2, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->stickers_manager_->get_stickers_object(sticker_ids_));
+  }
+
+ public:
+  GetStickersRequest(ActorShared<Td> td, uint64 request_id, string &&emoji, int32 limit)
+      : RequestActor(std::move(td), request_id), emoji_(std::move(emoji)), limit_(limit) {
+    set_tries(5);
+  }
+};
+
+class SearchStickersRequest : public RequestActor<> {
+  string emoji_;
+  int32 limit_;
+
+  vector<FileId> sticker_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    sticker_ids_ = td->stickers_manager_->search_stickers(emoji_, limit_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->stickers_manager_->get_stickers_object(sticker_ids_));
+  }
+
+ public:
+  SearchStickersRequest(ActorShared<Td> td, uint64 request_id, string &&emoji, int32 limit)
+      : RequestActor(std::move(td), request_id), emoji_(std::move(emoji)), limit_(limit) {
+  }
+};
+
+class GetInstalledStickerSetsRequest : public RequestActor<> {
+  bool is_masks_;
+
+  vector<int64> sticker_set_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    sticker_set_ids_ = td->stickers_manager_->get_installed_sticker_sets(is_masks_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->stickers_manager_->get_sticker_sets_object(-1, sticker_set_ids_, 1));
+  }
+
+ public:
+  GetInstalledStickerSetsRequest(ActorShared<Td> td, uint64 request_id, bool is_masks)
+      : RequestActor(std::move(td), request_id), is_masks_(is_masks) {
+  }
+};
+
+class GetArchivedStickerSetsRequest : public RequestActor<> {
+  bool is_masks_;
+  int64 offset_sticker_set_id_;
+  int32 limit_;
+
+  int32 total_count_;
+  vector<int64> sticker_set_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    std::tie(total_count_, sticker_set_ids_) = td->stickers_manager_->get_archived_sticker_sets(
+        is_masks_, offset_sticker_set_id_, limit_, get_tries() < 2, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->stickers_manager_->get_sticker_sets_object(total_count_, sticker_set_ids_, 1));
+  }
+
+ public:
+  GetArchivedStickerSetsRequest(ActorShared<Td> td, uint64 request_id, bool is_masks, int64 offset_sticker_set_id,
+                                int32 limit)
+      : RequestActor(std::move(td), request_id)
+      , is_masks_(is_masks)
+      , offset_sticker_set_id_(offset_sticker_set_id)
+      , limit_(limit) {
+  }
+};
+
+class GetTrendingStickerSetsRequest : public RequestActor<> {
+  vector<int64> sticker_set_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    sticker_set_ids_ = td->stickers_manager_->get_featured_sticker_sets(std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->stickers_manager_->get_sticker_sets_object(-1, sticker_set_ids_, 5));
+  }
+
+ public:
+  GetTrendingStickerSetsRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+  }
+};
+
+class GetAttachedStickerSetsRequest : public RequestActor<> {
+  FileId file_id_;
+
+  vector<int64> sticker_set_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    sticker_set_ids_ = td->stickers_manager_->get_attached_sticker_sets(file_id_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->stickers_manager_->get_sticker_sets_object(-1, sticker_set_ids_, 5));
+  }
+
+ public:
+  GetAttachedStickerSetsRequest(ActorShared<Td> td, uint64 request_id, int32 file_id)
+      : RequestActor(std::move(td), request_id), file_id_(file_id, 0) {
+  }
+};
+
+class GetStickerSetRequest : public RequestActor<> {
+  int64 set_id_;
+
+  int64 sticker_set_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    sticker_set_id_ = td->stickers_manager_->get_sticker_set(set_id_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->stickers_manager_->get_sticker_set_object(sticker_set_id_));
+  }
+
+ public:
+  GetStickerSetRequest(ActorShared<Td> td, uint64 request_id, int64 set_id)
+      : RequestActor(std::move(td), request_id), set_id_(set_id) {
+    set_tries(3);
+  }
+};
+
+class SearchStickerSetRequest : public RequestActor<> {
+  string name_;
+
+  int64 sticker_set_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    sticker_set_id_ = td->stickers_manager_->search_sticker_set(name_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->stickers_manager_->get_sticker_set_object(sticker_set_id_));
+  }
+
+ public:
+  SearchStickerSetRequest(ActorShared<Td> td, uint64 request_id, string &&name)
+      : RequestActor(std::move(td), request_id), name_(std::move(name)) {
+    set_tries(3);
+  }
+};
+
+class SearchInstalledStickerSetsRequest : public RequestActor<> {
+  bool is_masks_;
+  string query_;
+  int32 limit_;
+
+  std::pair<int32, vector<int64>> sticker_set_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    sticker_set_ids_ =
+        td->stickers_manager_->search_installed_sticker_sets(is_masks_, query_, limit_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->stickers_manager_->get_sticker_sets_object(sticker_set_ids_.first, sticker_set_ids_.second, 5));
+  }
+
+ public:
+  SearchInstalledStickerSetsRequest(ActorShared<Td> td, uint64 request_id, bool is_masks, string &&query, int32 limit)
+      : RequestActor(std::move(td), request_id), is_masks_(is_masks), query_(std::move(query)), limit_(limit) {
+  }
+};
+
+class SearchStickerSetsRequest : public RequestActor<> {
+  string query_;
+
+  vector<int64> sticker_set_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    sticker_set_ids_ = td->stickers_manager_->search_sticker_sets(query_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->stickers_manager_->get_sticker_sets_object(-1, sticker_set_ids_, 5));
+  }
+
+ public:
+  SearchStickerSetsRequest(ActorShared<Td> td, uint64 request_id, string &&query)
+      : RequestActor(std::move(td), request_id), query_(std::move(query)) {
+  }
+};
+
+class ChangeStickerSetRequest : public RequestOnceActor {
+  int64 set_id_;
+  bool is_installed_;
+  bool is_archived_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->stickers_manager_->change_sticker_set(set_id_, is_installed_, is_archived_, std::move(promise));
+  }
+
+ public:
+  ChangeStickerSetRequest(ActorShared<Td> td, uint64 request_id, int64 set_id, bool is_installed, bool is_archived)
+      : RequestOnceActor(std::move(td), request_id)
+      , set_id_(set_id)
+      , is_installed_(is_installed)
+      , is_archived_(is_archived) {
+    set_tries(4);
+  }
+};
+
+class ReorderInstalledStickerSetsRequest : public RequestOnceActor {
+  bool is_masks_;
+  vector<int64> sticker_set_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->stickers_manager_->reorder_installed_sticker_sets(is_masks_, sticker_set_ids_, std::move(promise));
+  }
+
+ public:
+  ReorderInstalledStickerSetsRequest(ActorShared<Td> td, uint64 request_id, bool is_masks,
+                                     vector<int64> &&sticker_set_ids)
+      : RequestOnceActor(std::move(td), request_id), is_masks_(is_masks), sticker_set_ids_(std::move(sticker_set_ids)) {
+  }
+};
+
+class UploadStickerFileRequest : public RequestOnceActor {
+  UserId user_id_;
+  tl_object_ptr<td_api::InputFile> sticker_;
+
+  FileId file_id;
+
+  void do_run(Promise<Unit> &&promise) override {
+    file_id = td->stickers_manager_->upload_sticker_file(user_id_, sticker_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->file_manager_->get_file_object(file_id));
+  }
+
+ public:
+  UploadStickerFileRequest(ActorShared<Td> td, uint64 request_id, int32 user_id,
+                           tl_object_ptr<td_api::InputFile> &&sticker)
+      : RequestOnceActor(std::move(td), request_id), user_id_(user_id), sticker_(std::move(sticker)) {
+  }
+};
+
+class CreateNewStickerSetRequest : public RequestOnceActor {
+  UserId user_id_;
+  string title_;
+  string name_;
+  bool is_masks_;
+  vector<tl_object_ptr<td_api::inputSticker>> stickers_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->stickers_manager_->create_new_sticker_set(user_id_, title_, name_, is_masks_, std::move(stickers_),
+                                                  std::move(promise));
+  }
+
+  void do_send_result() override {
+    auto set_id = td->stickers_manager_->search_sticker_set(name_, Auto());
+    if (set_id == 0) {
+      return send_error(Status::Error(500, "Created sticker set not found"));
+    }
+    send_result(td->stickers_manager_->get_sticker_set_object(set_id));
+  }
+
+ public:
+  CreateNewStickerSetRequest(ActorShared<Td> td, uint64 request_id, int32 user_id, string &&title, string &&name,
+                             bool is_masks, vector<tl_object_ptr<td_api::inputSticker>> &&stickers)
+      : RequestOnceActor(std::move(td), request_id)
+      , user_id_(user_id)
+      , title_(std::move(title))
+      , name_(std::move(name))
+      , is_masks_(is_masks)
+      , stickers_(std::move(stickers)) {
+  }
+};
+
+class AddStickerToSetRequest : public RequestOnceActor {
+  UserId user_id_;
+  string name_;
+  tl_object_ptr<td_api::inputSticker> sticker_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->stickers_manager_->add_sticker_to_set(user_id_, name_, std::move(sticker_), std::move(promise));
+  }
+
+  void do_send_result() override {
+    auto set_id = td->stickers_manager_->search_sticker_set(name_, Auto());
+    if (set_id == 0) {
+      return send_error(Status::Error(500, "Sticker set not found"));
+    }
+    send_result(td->stickers_manager_->get_sticker_set_object(set_id));
+  }
+
+ public:
+  AddStickerToSetRequest(ActorShared<Td> td, uint64 request_id, int32 user_id, string &&name,
+                         tl_object_ptr<td_api::inputSticker> &&sticker)
+      : RequestOnceActor(std::move(td), request_id)
+      , user_id_(user_id)
+      , name_(std::move(name))
+      , sticker_(std::move(sticker)) {
+  }
+};
+
+class SetStickerPositionInSetRequest : public RequestOnceActor {
+  tl_object_ptr<td_api::InputFile> sticker_;
+  int32 position_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->stickers_manager_->set_sticker_position_in_set(sticker_, position_, std::move(promise));
+  }
+
+ public:
+  SetStickerPositionInSetRequest(ActorShared<Td> td, uint64 request_id, tl_object_ptr<td_api::InputFile> &&sticker,
+                                 int32 position)
+      : RequestOnceActor(std::move(td), request_id), sticker_(std::move(sticker)), position_(position) {
+  }
+};
+
+class RemoveStickerFromSetRequest : public RequestOnceActor {
+  tl_object_ptr<td_api::InputFile> sticker_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->stickers_manager_->remove_sticker_from_set(sticker_, std::move(promise));
+  }
+
+ public:
+  RemoveStickerFromSetRequest(ActorShared<Td> td, uint64 request_id, tl_object_ptr<td_api::InputFile> &&sticker)
+      : RequestOnceActor(std::move(td), request_id), sticker_(std::move(sticker)) {
+  }
+};
+
+class GetRecentStickersRequest : public RequestActor<> {
+  bool is_attached_;
+
+  vector<FileId> sticker_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    sticker_ids_ = td->stickers_manager_->get_recent_stickers(is_attached_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->stickers_manager_->get_stickers_object(sticker_ids_));
+  }
+
+ public:
+  GetRecentStickersRequest(ActorShared<Td> td, uint64 request_id, bool is_attached)
+      : RequestActor(std::move(td), request_id), is_attached_(is_attached) {
+  }
+};
+
+class AddRecentStickerRequest : public RequestActor<> {
+  bool is_attached_;
+  tl_object_ptr<td_api::InputFile> input_file_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->stickers_manager_->add_recent_sticker(is_attached_, input_file_, std::move(promise));
+  }
+
+ public:
+  AddRecentStickerRequest(ActorShared<Td> td, uint64 request_id, bool is_attached,
+                          tl_object_ptr<td_api::InputFile> &&input_file)
+      : RequestActor(std::move(td), request_id), is_attached_(is_attached), input_file_(std::move(input_file)) {
+    set_tries(3);
+  }
+};
+
+class RemoveRecentStickerRequest : public RequestActor<> {
+  bool is_attached_;
+  tl_object_ptr<td_api::InputFile> input_file_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->stickers_manager_->remove_recent_sticker(is_attached_, input_file_, std::move(promise));
+  }
+
+ public:
+  RemoveRecentStickerRequest(ActorShared<Td> td, uint64 request_id, bool is_attached,
+                             tl_object_ptr<td_api::InputFile> &&input_file)
+      : RequestActor(std::move(td), request_id), is_attached_(is_attached), input_file_(std::move(input_file)) {
+    set_tries(3);
+  }
+};
+
+class ClearRecentStickersRequest : public RequestActor<> {
+  bool is_attached_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->stickers_manager_->clear_recent_stickers(is_attached_, std::move(promise));
+  }
+
+ public:
+  ClearRecentStickersRequest(ActorShared<Td> td, uint64 request_id, bool is_attached)
+      : RequestActor(std::move(td), request_id), is_attached_(is_attached) {
+    set_tries(3);
+  }
+};
+
+class GetFavoriteStickersRequest : public RequestActor<> {
+  vector<FileId> sticker_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    sticker_ids_ = td->stickers_manager_->get_favorite_stickers(std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->stickers_manager_->get_stickers_object(sticker_ids_));
+  }
+
+ public:
+  GetFavoriteStickersRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+  }
+};
+
+class AddFavoriteStickerRequest : public RequestOnceActor {
+  tl_object_ptr<td_api::InputFile> input_file_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->stickers_manager_->add_favorite_sticker(input_file_, std::move(promise));
+  }
+
+ public:
+  AddFavoriteStickerRequest(ActorShared<Td> td, uint64 request_id, tl_object_ptr<td_api::InputFile> &&input_file)
+      : RequestOnceActor(std::move(td), request_id), input_file_(std::move(input_file)) {
+    set_tries(3);
+  }
+};
+
+class RemoveFavoriteStickerRequest : public RequestOnceActor {
+  tl_object_ptr<td_api::InputFile> input_file_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->stickers_manager_->remove_favorite_sticker(input_file_, std::move(promise));
+  }
+
+ public:
+  RemoveFavoriteStickerRequest(ActorShared<Td> td, uint64 request_id, tl_object_ptr<td_api::InputFile> &&input_file)
+      : RequestOnceActor(std::move(td), request_id), input_file_(std::move(input_file)) {
+    set_tries(3);
+  }
+};
+
+class GetStickerEmojisRequest : public RequestActor<> {
+  tl_object_ptr<td_api::InputFile> input_file_;
+
+  vector<string> emojis_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    emojis_ = td->stickers_manager_->get_sticker_emojis(input_file_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(make_tl_object<td_api::stickerEmojis>(std::move(emojis_)));
+  }
+
+ public:
+  GetStickerEmojisRequest(ActorShared<Td> td, uint64 request_id, tl_object_ptr<td_api::InputFile> &&input_file)
+      : RequestActor(std::move(td), request_id), input_file_(std::move(input_file)) {
+    set_tries(3);
+  }
+};
+
+class GetSavedAnimationsRequest : public RequestActor<> {
+  vector<FileId> animation_ids_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    animation_ids_ = td->animations_manager_->get_saved_animations(std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(make_tl_object<td_api::animations>(transform(std::move(animation_ids_), [td = td](FileId animation_id) {
+      return td->animations_manager_->get_animation_object(animation_id, "GetSavedAnimationsRequest");
+    })));
+  }
+
+ public:
+  GetSavedAnimationsRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+  }
+};
+
+class AddSavedAnimationRequest : public RequestOnceActor {
+  tl_object_ptr<td_api::InputFile> input_file_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->animations_manager_->add_saved_animation(input_file_, std::move(promise));
+  }
+
+ public:
+  AddSavedAnimationRequest(ActorShared<Td> td, uint64 request_id, tl_object_ptr<td_api::InputFile> &&input_file)
+      : RequestOnceActor(std::move(td), request_id), input_file_(std::move(input_file)) {
+    set_tries(3);
+  }
+};
+
+class RemoveSavedAnimationRequest : public RequestOnceActor {
+  tl_object_ptr<td_api::InputFile> input_file_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->animations_manager_->remove_saved_animation(input_file_, std::move(promise));
+  }
+
+ public:
+  RemoveSavedAnimationRequest(ActorShared<Td> td, uint64 request_id, tl_object_ptr<td_api::InputFile> &&input_file)
+      : RequestOnceActor(std::move(td), request_id), input_file_(std::move(input_file)) {
+    set_tries(3);
+  }
+};
+
+class GetInlineQueryResultsRequest : public RequestOnceActor {
+  UserId bot_user_id_;
+  DialogId dialog_id_;
+  Location user_location_;
+  string query_;
+  string offset_;
+
+  uint64 query_hash_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    query_hash_ = td->inline_queries_manager_->send_inline_query(bot_user_id_, dialog_id_, user_location_, query_,
+                                                                 offset_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->inline_queries_manager_->get_inline_query_results_object(query_hash_));
+  }
+
+ public:
+  GetInlineQueryResultsRequest(ActorShared<Td> td, uint64 request_id, int32 bot_user_id, int64 dialog_id,
+                               const tl_object_ptr<td_api::location> &user_location, string query, string offset)
+      : RequestOnceActor(std::move(td), request_id)
+      , bot_user_id_(bot_user_id)
+      , dialog_id_(dialog_id)
+      , user_location_(user_location)
+      , query_(std::move(query))
+      , offset_(std::move(offset))
+      , query_hash_(0) {
+  }
+};
+
+class AnswerInlineQueryRequest : public RequestOnceActor {
+  int64 inline_query_id_;
+  bool is_personal_;
+  vector<tl_object_ptr<td_api::InputInlineQueryResult>> results_;
+  int32 cache_time_;
+  string next_offset_;
+  string switch_pm_text_;
+  string switch_pm_parameter_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->inline_queries_manager_->answer_inline_query(inline_query_id_, is_personal_, std::move(results_), cache_time_,
+                                                     next_offset_, switch_pm_text_, switch_pm_parameter_,
+                                                     std::move(promise));
+  }
+
+ public:
+  AnswerInlineQueryRequest(ActorShared<Td> td, uint64 request_id, int64 inline_query_id, bool is_personal,
+                           vector<tl_object_ptr<td_api::InputInlineQueryResult>> &&results, int32 cache_time,
+                           string next_offset, string switch_pm_text, string switch_pm_parameter)
+      : RequestOnceActor(std::move(td), request_id)
+      , inline_query_id_(inline_query_id)
+      , is_personal_(is_personal)
+      , results_(std::move(results))
+      , cache_time_(cache_time)
+      , next_offset_(std::move(next_offset))
+      , switch_pm_text_(std::move(switch_pm_text))
+      , switch_pm_parameter_(std::move(switch_pm_parameter)) {
+  }
+};
+
+class GetCallbackQueryAnswerRequest : public RequestOnceActor {
+  FullMessageId full_message_id_;
+  tl_object_ptr<td_api::CallbackQueryPayload> payload_;
+
+  int64 result_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    result_id_ = td->callback_queries_manager_->send_callback_query(full_message_id_, payload_, std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->callback_queries_manager_->get_callback_query_answer_object(result_id_));
+  }
+
+  void do_send_error(Status &&status) override {
+    if (status.code() == 502 && td->messages_manager_->is_message_edited_recently(full_message_id_, 31)) {
+      return send_result(make_tl_object<td_api::callbackQueryAnswer>());
+    }
+    send_error(std::move(status));
+  }
+
+ public:
+  GetCallbackQueryAnswerRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int64 message_id,
+                                tl_object_ptr<td_api::CallbackQueryPayload> payload)
+      : RequestOnceActor(std::move(td), request_id)
+      , full_message_id_(DialogId(dialog_id), MessageId(message_id))
+      , payload_(std::move(payload))
+      , result_id_(0) {
+  }
+};
+
+class AnswerCallbackQueryRequest : public RequestOnceActor {
+  int64 callback_query_id_;
+  string text_;
+  bool show_alert_;
+  string url_;
+  int32 cache_time_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->callback_queries_manager_->answer_callback_query(callback_query_id_, text_, show_alert_, url_, cache_time_,
+                                                         std::move(promise));
+  }
+
+ public:
+  AnswerCallbackQueryRequest(ActorShared<Td> td, uint64 request_id, int64 callback_query_id, string text,
+                             bool show_alert, string url, int32 cache_time)
+      : RequestOnceActor(std::move(td), request_id)
+      , callback_query_id_(callback_query_id)
+      , text_(std::move(text))
+      , show_alert_(show_alert)
+      , url_(std::move(url))
+      , cache_time_(cache_time) {
+  }
+};
+
+class AnswerShippingQueryRequest : public RequestOnceActor {
+  int64 shipping_query_id_;
+  vector<tl_object_ptr<td_api::shippingOption>> shipping_options_;
+  string error_message_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    answer_shipping_query(shipping_query_id_, std::move(shipping_options_), error_message_, std::move(promise));
+  }
+
+ public:
+  AnswerShippingQueryRequest(ActorShared<Td> td, uint64 request_id, int64 shipping_query_id,
+                             vector<tl_object_ptr<td_api::shippingOption>> shipping_options, string error_message)
+      : RequestOnceActor(std::move(td), request_id)
+      , shipping_query_id_(shipping_query_id)
+      , shipping_options_(std::move(shipping_options))
+      , error_message_(std::move(error_message)) {
+  }
+};
+
+class AnswerPreCheckoutQueryRequest : public RequestOnceActor {
+  int64 pre_checkout_query_id_;
+  string error_message_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    answer_pre_checkout_query(pre_checkout_query_id_, error_message_, std::move(promise));
+  }
+
+ public:
+  AnswerPreCheckoutQueryRequest(ActorShared<Td> td, uint64 request_id, int64 pre_checkout_query_id,
+                                string error_message)
+      : RequestOnceActor(std::move(td), request_id)
+      , pre_checkout_query_id_(pre_checkout_query_id)
+      , error_message_(std::move(error_message)) {
+  }
+};
+
+class GetPaymentFormRequest : public RequestActor<tl_object_ptr<td_api::paymentForm>> {
+  FullMessageId full_message_id_;
+
+  tl_object_ptr<td_api::paymentForm> payment_form_;
+
+  void do_run(Promise<tl_object_ptr<td_api::paymentForm>> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(payment_form_));
+      return;
+    }
+
+    td->messages_manager_->get_payment_form(full_message_id_, std::move(promise));
+  }
+
+  void do_set_result(tl_object_ptr<td_api::paymentForm> &&result) override {
+    payment_form_ = std::move(result);
+  }
+
+  void do_send_result() override {
+    CHECK(payment_form_ != nullptr);
+    send_result(std::move(payment_form_));
+  }
+
+ public:
+  GetPaymentFormRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int64 message_id)
+      : RequestActor(std::move(td), request_id), full_message_id_(DialogId(dialog_id), MessageId(message_id)) {
+  }
+};
+
+class ValidateOrderInfoRequest : public RequestActor<tl_object_ptr<td_api::validatedOrderInfo>> {
+  FullMessageId full_message_id_;
+  tl_object_ptr<td_api::orderInfo> order_info_;
+  bool allow_save_;
+
+  tl_object_ptr<td_api::validatedOrderInfo> validated_order_info_;
+
+  void do_run(Promise<tl_object_ptr<td_api::validatedOrderInfo>> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(validated_order_info_));
+      return;
+    }
+
+    td->messages_manager_->validate_order_info(full_message_id_, std::move(order_info_), allow_save_,
+                                               std::move(promise));
+  }
+
+  void do_set_result(tl_object_ptr<td_api::validatedOrderInfo> &&result) override {
+    validated_order_info_ = std::move(result);
+  }
+
+  void do_send_result() override {
+    CHECK(validated_order_info_ != nullptr);
+    send_result(std::move(validated_order_info_));
+  }
+
+ public:
+  ValidateOrderInfoRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int64 message_id,
+                           tl_object_ptr<td_api::orderInfo> order_info, bool allow_save)
+      : RequestActor(std::move(td), request_id)
+      , full_message_id_(DialogId(dialog_id), MessageId(message_id))
+      , order_info_(std::move(order_info))
+      , allow_save_(allow_save) {
+  }
+};
+
+class SendPaymentFormRequest : public RequestActor<tl_object_ptr<td_api::paymentResult>> {
+  FullMessageId full_message_id_;
+  string order_info_id_;
+  string shipping_option_id_;
+  tl_object_ptr<td_api::InputCredentials> credentials_;
+
+  tl_object_ptr<td_api::paymentResult> payment_result_;
+
+  void do_run(Promise<tl_object_ptr<td_api::paymentResult>> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(payment_result_));
+      return;
+    }
+
+    td->messages_manager_->send_payment_form(full_message_id_, order_info_id_, shipping_option_id_, credentials_,
+                                             std::move(promise));
+  }
+
+  void do_set_result(tl_object_ptr<td_api::paymentResult> &&result) override {
+    payment_result_ = std::move(result);
+  }
+
+  void do_send_result() override {
+    CHECK(payment_result_ != nullptr);
+    send_result(std::move(payment_result_));
+  }
+
+ public:
+  SendPaymentFormRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int64 message_id, string order_info_id,
+                         string shipping_option_id, tl_object_ptr<td_api::InputCredentials> credentials)
+      : RequestActor(std::move(td), request_id)
+      , full_message_id_(DialogId(dialog_id), MessageId(message_id))
+      , order_info_id_(std::move(order_info_id))
+      , shipping_option_id_(std::move(shipping_option_id))
+      , credentials_(std::move(credentials)) {
+  }
+};
+
+class GetPaymentReceiptRequest : public RequestActor<tl_object_ptr<td_api::paymentReceipt>> {
+  FullMessageId full_message_id_;
+
+  tl_object_ptr<td_api::paymentReceipt> payment_receipt_;
+
+  void do_run(Promise<tl_object_ptr<td_api::paymentReceipt>> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(payment_receipt_));
+      return;
+    }
+
+    td->messages_manager_->get_payment_receipt(full_message_id_, std::move(promise));
+  }
+
+  void do_set_result(tl_object_ptr<td_api::paymentReceipt> &&result) override {
+    payment_receipt_ = std::move(result);
+  }
+
+  void do_send_result() override {
+    CHECK(payment_receipt_ != nullptr);
+    send_result(std::move(payment_receipt_));
+  }
+
+ public:
+  GetPaymentReceiptRequest(ActorShared<Td> td, uint64 request_id, int64 dialog_id, int64 message_id)
+      : RequestActor(std::move(td), request_id), full_message_id_(DialogId(dialog_id), MessageId(message_id)) {
+  }
+};
+
+class GetSavedOrderInfoRequest : public RequestActor<tl_object_ptr<td_api::orderInfo>> {
+  tl_object_ptr<td_api::orderInfo> order_info_;
+
+  void do_run(Promise<tl_object_ptr<td_api::orderInfo>> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(order_info_));
+      return;
+    }
+
+    get_saved_order_info(std::move(promise));
+  }
+
+  void do_set_result(tl_object_ptr<td_api::orderInfo> &&result) override {
+    order_info_ = std::move(result);
+  }
+
+  void do_send_result() override {
+    send_result(std::move(order_info_));
+  }
+
+ public:
+  GetSavedOrderInfoRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+  }
+};
+
+class DeleteSavedOrderInfoRequest : public RequestOnceActor {
+  void do_run(Promise<Unit> &&promise) override {
+    delete_saved_order_info(std::move(promise));
+  }
+
+ public:
+  DeleteSavedOrderInfoRequest(ActorShared<Td> td, uint64 request_id) : RequestOnceActor(std::move(td), request_id) {
+  }
+};
+
+class DeleteSavedCredentialsRequest : public RequestOnceActor {
+  void do_run(Promise<Unit> &&promise) override {
+    delete_saved_credentials(std::move(promise));
+  }
+
+ public:
+  DeleteSavedCredentialsRequest(ActorShared<Td> td, uint64 request_id) : RequestOnceActor(std::move(td), request_id) {
+  }
+};
+
+class GetSupportUserRequest : public RequestActor<> {
+  UserId user_id_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    user_id_ = td->contacts_manager_->get_support_user(std::move(promise));
+  }
+
+  void do_send_result() override {
+    send_result(td->contacts_manager_->get_user_object(user_id_));
+  }
+
+ public:
+  GetSupportUserRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+  }
+};
+
+class GetWallpapersRequest : public RequestActor<tl_object_ptr<td_api::wallpapers>> {
+  tl_object_ptr<td_api::wallpapers> wallpapers_;
+
+  void do_run(Promise<tl_object_ptr<td_api::wallpapers>> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(wallpapers_));
+      return;
+    }
+
+    td->create_handler<GetWallpapersQuery>(std::move(promise))->send();
+  }
+
+  void do_set_result(tl_object_ptr<td_api::wallpapers> &&result) override {
+    wallpapers_ = std::move(result);
+  }
+
+  void do_send_result() override {
+    CHECK(wallpapers_ != nullptr);
+    send_result(std::move(wallpapers_));
+  }
+
+ public:
+  GetWallpapersRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+  }
+};
+
+class GetRecentlyVisitedTMeUrlsRequest : public RequestActor<tl_object_ptr<td_api::tMeUrls>> {
+  string referrer_;
+
+  tl_object_ptr<td_api::tMeUrls> urls_;
+
+  void do_run(Promise<tl_object_ptr<td_api::tMeUrls>> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(urls_));
+      return;
+    }
+
+    td->create_handler<GetRecentMeUrlsQuery>(std::move(promise))->send(referrer_);
+  }
+
+  void do_set_result(tl_object_ptr<td_api::tMeUrls> &&result) override {
+    urls_ = std::move(result);
+  }
+
+  void do_send_result() override {
+    CHECK(urls_ != nullptr);
+    send_result(std::move(urls_));
+  }
+
+ public:
+  GetRecentlyVisitedTMeUrlsRequest(ActorShared<Td> td, uint64 request_id, string referrer)
+      : RequestActor(std::move(td), request_id), referrer_(std::move(referrer)) {
+  }
+};
+
+class SendCustomRequestRequest : public RequestActor<string> {
+  string method_;
+  string parameters_;
+
+  string request_result_;
+
+  void do_run(Promise<string> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(request_result_));
+      return;
+    }
+
+    td->create_handler<SendCustomRequestQuery>(std::move(promise))->send(method_, parameters_);
+  }
+
+  void do_set_result(string &&result) override {
+    request_result_ = std::move(result);
+  }
+
+  void do_send_result() override {
+    send_result(make_tl_object<td_api::customRequestResult>(request_result_));
+  }
+
+ public:
+  SendCustomRequestRequest(ActorShared<Td> td, uint64 request_id, string &&method, string &&parameters)
+      : RequestActor(std::move(td), request_id), method_(method), parameters_(parameters) {
+  }
+};
+
+class AnswerCustomQueryRequest : public RequestOnceActor {
+  int64 custom_query_id_;
+  string data_;
+
+  void do_run(Promise<Unit> &&promise) override {
+    td->create_handler<AnswerCustomQueryQuery>(std::move(promise))->send(custom_query_id_, data_);
+  }
+
+ public:
+  AnswerCustomQueryRequest(ActorShared<Td> td, uint64 request_id, int64 custom_query_id, string data)
+      : RequestOnceActor(std::move(td), request_id), custom_query_id_(custom_query_id), data_(std::move(data)) {
+  }
+};
+
+class GetCountryCodeRequest : public RequestActor<string> {
+  string country_code_;
+
+  void do_run(Promise<string> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(country_code_));
+      return;
+    }
+
+    td->create_handler<GetNearestDcQuery>(std::move(promise))->send();
+  }
+
+  void do_set_result(string &&result) override {
+    country_code_ = std::move(result);
+  }
+
+  void do_send_result() override {
+    send_result(make_tl_object<td_api::text>(country_code_));
+  }
+
+ public:
+  GetCountryCodeRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+  }
+};
+
+class GetInviteTextRequest : public RequestActor<string> {
+  string text_;
+
+  void do_run(Promise<string> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(text_));
+      return;
+    }
+
+    td->create_handler<GetInviteTextQuery>(std::move(promise))->send();
+  }
+
+  void do_set_result(string &&result) override {
+    text_ = std::move(result);
+  }
+
+  void do_send_result() override {
+    send_result(make_tl_object<td_api::text>(text_));
+  }
+
+ public:
+  GetInviteTextRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+  }
+};
+
+class GetTermsOfServiceRequest : public RequestActor<string> {
+  string text_;
+
+  void do_run(Promise<string> &&promise) override {
+    if (get_tries() < 2) {
+      promise.set_value(std::move(text_));
+      return;
+    }
+
+    td->create_handler<GetTermsOfServiceQuery>(std::move(promise))->send();
+  }
+
+  void do_set_result(string &&result) override {
+    text_ = std::move(result);
+  }
+
+  void do_send_result() override {
+    send_result(make_tl_object<td_api::text>(text_));
+  }
+
+ public:
+  GetTermsOfServiceRequest(ActorShared<Td> td, uint64 request_id) : RequestActor(std::move(td), request_id) {
+  }
+};
+
+/** Td **/
+Td::Td(std::unique_ptr<TdCallback> callback) : callback_(std::move(callback)) {
+}
+
+void Td::on_alarm_timeout_callback(void *td_ptr, int64 alarm_id) {
+  auto td = static_cast<Td *>(td_ptr);
+  auto td_id = td->actor_id(td);
+  send_closure_later(td_id, &Td::on_alarm_timeout, alarm_id);
+}
+
+void Td::on_alarm_timeout(int64 alarm_id) {
+  if (alarm_id == ONLINE_ALARM_ID) {
+    on_online_updated(false, true);
+    return;
+  }
+  if (alarm_id == PING_SERVER_ALARM_ID && updates_manager_ != nullptr) {
+    updates_manager_->ping_server();
+    alarm_timeout_.set_timeout_in(PING_SERVER_ALARM_ID, PING_SERVER_TIMEOUT + Random::fast(0, PING_SERVER_TIMEOUT / 5));
+    return;
+  }
+  auto it = pending_alarms_.find(alarm_id);
+  CHECK(it != pending_alarms_.end());
+  uint64 request_id = it->second;
+  pending_alarms_.erase(alarm_id);
+  send_result(request_id, make_tl_object<td_api::ok>());
+}
+
+void Td::on_online_updated(bool force, bool send_update) {
+  if (close_flag_ >= 2 || auth_manager_->is_bot() || !auth_manager_->is_authorized()) {
+    return;
+  }
+  if (force || is_online_) {
+    contacts_manager_->set_my_online_status(is_online_, send_update, true);
+    if (!update_status_query_.empty()) {
+      LOG(INFO) << "Cancel previous update status query";
+      cancel_query(update_status_query_);
+    }
+    update_status_query_ = create_handler<UpdateStatusQuery>()->send(!is_online_);
+  }
+  if (is_online_) {
+    alarm_timeout_.set_timeout_in(ONLINE_ALARM_ID, ONLINE_TIMEOUT);
+  } else {
+    alarm_timeout_.cancel_timeout(ONLINE_ALARM_ID);
+  }
+}
+
+void Td::on_update_status_success(bool is_online) {
+  if (is_online == is_online_) {
+    if (!update_status_query_.empty()) {
+      update_status_query_ = NetQueryRef();
+    }
+    contacts_manager_->set_my_online_status(is_online_, true, false);
+  }
+}
+
+void Td::on_channel_unban_timeout(int64 channel_id_long) {
+  if (close_flag_ >= 2) {
+    return;
+  }
+  contacts_manager_->on_channel_unban_timeout(ChannelId(narrow_cast<int32>(channel_id_long)));
+}
+
+bool Td::is_online() const {
+  return is_online_;
+}
+
+void Td::request(uint64 id, tl_object_ptr<td_api::Function> function) {
+  request_set_.insert(id);
+
+  if (id == 0) {
+    LOG(ERROR) << "Receive request with id == 0";
+    return send_error_raw(id, 400, "Wrong request id == 0");
+  }
+  if (function == nullptr) {
+    LOG(ERROR) << "Receive empty request";
+    return send_error_raw(id, 400, "Request is empty");
+  }
+
+  switch (state_) {
+    case State::WaitParameters: {
+      switch (function->get_id()) {
+        case td_api::getAuthorizationState::ID:
+          return send_closure(actor_id(this), &Td::send_result, id,
+                              td_api::make_object<td_api::authorizationStateWaitTdlibParameters>());
+        case td_api::setTdlibParameters::ID:
+          return answer_ok_query(
+              id, set_parameters(std::move(move_tl_object_as<td_api::setTdlibParameters>(function)->parameters_)));
+        default:
+          return send_error_raw(id, 401, "Initialization parameters are needed");
+      }
+      break;
+    }
+    case State::Decrypt: {
+      string encryption_key;
+      switch (function->get_id()) {
+        case td_api::getAuthorizationState::ID:
+          return send_closure(
+              actor_id(this), &Td::send_result, id,
+              td_api::make_object<td_api::authorizationStateWaitEncryptionKey>(encryption_info_.is_encrypted));
+        case td_api::checkDatabaseEncryptionKey::ID: {
+          auto check_key = move_tl_object_as<td_api::checkDatabaseEncryptionKey>(function);
+          encryption_key = std::move(check_key->encryption_key_);
+          break;
+        }
+        case td_api::setDatabaseEncryptionKey::ID: {
+          auto set_key = move_tl_object_as<td_api::setDatabaseEncryptionKey>(function);
+          encryption_key = std::move(set_key->new_encryption_key_);
+          break;
+        }
+        case td_api::close::ID:
+          return close();
+        case td_api::destroy::ID:
+          return destroy();
+        default:
+          return send_error_raw(id, 401, "Database encryption key is needed");
+      }
+      return answer_ok_query(id, init(as_db_key(encryption_key)));
+    }
+    case State::Close: {
+      if (function->get_id() == td_api::getAuthorizationState::ID) {
+        if (close_flag_ == 5) {
+          return send_closure(actor_id(this), &Td::send_result, id,
+                              td_api::make_object<td_api::authorizationStateClosed>());
+        } else {
+          return send_closure(actor_id(this), &Td::send_result, id,
+                              td_api::make_object<td_api::authorizationStateClosing>());
+        }
+      }
+      return send_error_raw(id, 401, "Unauthorized");
+    }
+    case State::Run:
+      break;
+  }
+
+  VLOG(td_requests) << "Receive request " << id << ": " << to_string(function);
+  downcast_call(*function, [this, id](auto &request) { this->on_request(id, request); });
+}
+
+td_api::object_ptr<td_api::Object> Td::static_request(td_api::object_ptr<td_api::Function> function) {
+  VLOG(td_requests) << "Receive static request: " << to_string(function);
+
+  td_api::object_ptr<td_api::Object> response;
+  downcast_call(*function, [&response](auto &request) { response = Td::do_static_request(request); });
+
+  VLOG(td_requests) << "Sending result for static request: " << to_string(response);
+  return response;
+}
+
+void Td::add_handler(uint64 id, std::shared_ptr<ResultHandler> handler) {
+  result_handlers_.emplace_back(id, handler);
+}
+
+std::shared_ptr<Td::ResultHandler> Td::extract_handler(uint64 id) {
+  std::shared_ptr<Td::ResultHandler> result;
+  for (size_t i = 0; i < result_handlers_.size(); i++) {
+    if (result_handlers_[i].first == id) {
+      result = std::move(result_handlers_[i].second);
+      result_handlers_.erase(result_handlers_.begin() + i);
+      break;
+    }
+  }
+  return result;
+}
+
+void Td::invalidate_handler(ResultHandler *handler) {
+  for (size_t i = 0; i < result_handlers_.size(); i++) {
+    if (result_handlers_[i].second.get() == handler) {
+      result_handlers_.erase(result_handlers_.begin() + i);
+      i--;
+    }
+  }
+}
+
+void Td::send(NetQueryPtr &&query) {
+  VLOG(net_query) << "Send " << query << " to dispatcher";
+  query->debug("Td: send to NetQueryDispatcher");
+  query->set_callback(actor_shared(this, 1));
+  G()->net_query_dispatcher().dispatch(std::move(query));
+}
+
+void Td::update_qts(int32 qts) {
+  if (close_flag_ > 1) {
+    return;
+  }
+
+  updates_manager_->set_qts(qts);
+}
+
+void Td::force_get_difference() {
+  if (close_flag_) {
+    return;
+  }
+
+  updates_manager_->get_difference("force_get_difference");
+}
+
+void Td::on_result(NetQueryPtr query) {
+  query->debug("Td: received from DcManager");
+  VLOG(net_query) << "on_result " << query;
+  if (close_flag_ > 1) {
+    return;
+  }
+
+  if (query->id() == 0) {
+    if (query->is_error()) {
+      query->clear();
+      updates_manager_->schedule_get_difference("error in update");
+      LOG(ERROR) << "Error in update";
+      return;
+    }
+    auto ok = query->move_as_ok();
+    TlBufferParser parser(&ok);
+    auto ptr = telegram_api::Updates::fetch(parser);
+    if (parser.get_error()) {
+      LOG(ERROR) << "Failed to fetch update: " << parser.get_error() << format::as_hex_dump<4>(ok.as_slice());
+      updates_manager_->schedule_get_difference("failed to fetch update");
+    } else {
+      updates_manager_->on_get_updates(std::move(ptr));
+      if (auth_manager_->is_bot()) {
+        alarm_timeout_.set_timeout_in(PING_SERVER_ALARM_ID,
+                                      PING_SERVER_TIMEOUT + Random::fast(0, PING_SERVER_TIMEOUT / 5));
+      }
+    }
+    return;
+  }
+  auto handler = extract_handler(query->id());
+  if (handler == nullptr) {
+    query->clear();
+    LOG_IF(WARNING, !query->is_ok() || query->ok_tl_constructor() != telegram_api::upload_file::ID)
+        << tag("NetQuery", query) << " is ignored: no handlers found";
+    return;
+  }
+  handler->on_result(std::move(query));
+}
+
+bool Td::is_internal_config_option(Slice name) {
+  return name == "call_ring_timeout_ms" || name == "call_receive_timeout_ms" || name == "channels_read_media_period" ||
+         name == "edit_time_limit" || name == "revoke_pm_inbox" || name == "revoke_time_limit" ||
+         name == "revoke_pm_time_limit" || name == "rating_e_decay" || name == "saved_animations_limit" ||
+         name == "recent_stickers_limit" || name == "auth";
+}
+
+void Td::on_config_option_updated(const string &name) {
+  if (close_flag_) {
+    return;
+  }
+  if (name == "auth") {
+    on_authorization_lost();
+    return;
+  } else if (name == "saved_animations_limit") {
+    return animations_manager_->on_update_saved_animations_limit(G()->shared_config().get_option_integer(name));
+  } else if (name == "recent_stickers_limit") {
+    return stickers_manager_->on_update_recent_stickers_limit(G()->shared_config().get_option_integer(name));
+  } else if (name == "favorite_stickers_limit") {
+    stickers_manager_->on_update_favorite_stickers_limit(G()->shared_config().get_option_integer(name));
+  } else if (name == "my_id") {
+    G()->set_my_id(G()->shared_config().get_option_integer(name));
+  } else if (name == "session_count") {
+    G()->net_query_dispatcher().update_session_count();
+  } else if (name == "use_pfs") {
+    G()->net_query_dispatcher().update_use_pfs();
+  } else if (name == "use_storage_optimizer") {
+    send_closure(storage_manager_, &StorageManager::update_use_storage_optimizer);
+  } else if (name == "rating_e_decay") {
+    return send_closure(top_dialog_manager_, &TopDialogManager::update_rating_e_decay);
+  } else if (is_internal_config_option(name)) {
+    return;
+  }
+  // send_closure was already used in the callback
+  send_update(make_tl_object<td_api::updateOption>(name, G()->shared_config().get_option_value(name)));
+}
+
+tl_object_ptr<td_api::ConnectionState> Td::get_connection_state_object(StateManager::State state) {
+  switch (state) {
+    case StateManager::State::Empty:
+      UNREACHABLE();
+      return nullptr;
+    case StateManager::State::WaitingForNetwork:
+      return make_tl_object<td_api::connectionStateWaitingForNetwork>();
+    case StateManager::State::ConnectingToProxy:
+      return make_tl_object<td_api::connectionStateConnectingToProxy>();
+    case StateManager::State::Connecting:
+      return make_tl_object<td_api::connectionStateConnecting>();
+    case StateManager::State::Updating:
+      return make_tl_object<td_api::connectionStateUpdating>();
+    case StateManager::State::Ready:
+      return make_tl_object<td_api::connectionStateReady>();
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+void Td::on_connection_state_changed(StateManager::State new_state) {
+  if (new_state == connection_state_) {
+    LOG(ERROR) << "State manager sends update about unchanged state " << static_cast<int32>(new_state);
+    return;
+  }
+  connection_state_ = new_state;
+
+  send_closure(actor_id(this), &Td::send_update,
+               make_tl_object<td_api::updateConnectionState>(get_connection_state_object(connection_state_)));
+}
+
+void Td::on_authorization_lost() {
+  LOG(WARNING) << "on_authorization_lost";
+  destroy();
+}
+
+static td_api::object_ptr<td_api::error> make_error(int32 code, CSlice error) {
+  return td_api::make_object<td_api::error>(code, error.str());
+}
+
+void Td::start_up() {
+  always_wait_for_mailbox();
+
+  uint64 check_endianness = 0x0706050403020100;
+  auto check_endianness_raw = reinterpret_cast<const unsigned char *>(&check_endianness);
+  for (unsigned char c = 0; c < 8; c++) {
+    auto symbol = check_endianness_raw[static_cast<size_t>(c)];
+    LOG_IF(FATAL, symbol != c) << "TDLib requires little-endian platform";
+  }
+
+  CHECK(state_ == State::WaitParameters);
+  send_update(td_api::make_object<td_api::updateAuthorizationState>(
+      td_api::make_object<td_api::authorizationStateWaitTdlibParameters>()));
+}
+
+void Td::tear_down() {
+  CHECK(close_flag_ == 5);
+}
+
+void Td::hangup_shared() {
+  auto token = get_link_token();
+  auto type = Container<int>::type_from_id(token);
+
+  if (type == RequestActorIdType) {
+    request_actors_.erase(get_link_token());
+    dec_request_actor_refcnt();
+  } else if (type == ActorIdType) {
+    dec_actor_refcnt();
+  } else {
+    LOG(FATAL) << "Unknown hangup_shared of type " << type;
+  }
+}
+
+void Td::hangup() {
+  close();
+  dec_stop_cnt();
+}
+
+ActorShared<Td> Td::create_reference() {
+  inc_actor_refcnt();
+  return actor_shared(this, ActorIdType);
+}
+void Td::inc_actor_refcnt() {
+  actor_refcnt_++;
+}
+
+void Td::dec_actor_refcnt() {
+  actor_refcnt_--;
+  if (actor_refcnt_ == 0) {
+    if (close_flag_ == 2) {
+      create_reference();
+      close_flag_ = 3;
+    } else if (close_flag_ == 3) {
+      LOG(WARNING) << "ON_ACTORS_CLOSED";
+      Timer timer;
+      animations_manager_.reset();
+      LOG(DEBUG) << "AnimationsManager was cleared " << timer;
+      audios_manager_.reset();
+      LOG(DEBUG) << "AudiosManager was cleared " << timer;
+      auth_manager_.reset();
+      LOG(DEBUG) << "AuthManager was cleared " << timer;
+      change_phone_number_manager_.reset();
+      LOG(DEBUG) << "ChangePhoneNumberManager was cleared " << timer;
+      contacts_manager_.reset();
+      LOG(DEBUG) << "ContactsManager was cleared " << timer;
+      documents_manager_.reset();
+      LOG(DEBUG) << "DocumentsManager was cleared " << timer;
+      file_manager_.reset();
+      LOG(DEBUG) << "FileManager was cleared " << timer;
+      inline_queries_manager_.reset();
+      LOG(DEBUG) << "InlineQueriesManager was cleared " << timer;
+      messages_manager_.reset();
+      LOG(DEBUG) << "MessagesManager was cleared " << timer;
+      stickers_manager_.reset();
+      LOG(DEBUG) << "StickersManager was cleared " << timer;
+      updates_manager_.reset();
+      LOG(DEBUG) << "UpdatesManager was cleared " << timer;
+      video_notes_manager_.reset();
+      LOG(DEBUG) << "VideoNotesManager was cleared " << timer;
+      videos_manager_.reset();
+      LOG(DEBUG) << "VideosManager was cleared " << timer;
+      voice_notes_manager_.reset();
+      LOG(DEBUG) << "VoiceNotesManager was cleared " << timer;
+      web_pages_manager_.reset();
+      LOG(DEBUG) << "WebPagesManager was cleared " << timer;
+      Promise<> promise = PromiseCreator::lambda([actor_id = create_reference()](Unit) mutable { actor_id.reset(); });
+
+      if (destroy_flag_) {
+        G()->close_and_destroy_all(std::move(promise));
+      } else {
+        G()->close_all(std::move(promise));
+      }
+      // NetQueryDispatcher will be closed automatically
+      close_flag_ = 4;
+    } else if (close_flag_ == 4) {
+      on_closed();
+    } else {
+      UNREACHABLE();
+    }
+  }
+}
+
+void Td::on_closed() {
+  LOG(WARNING) << "ON_CLOSED";
+  close_flag_ = 5;
+  send_update(
+      td_api::make_object<td_api::updateAuthorizationState>(td_api::make_object<td_api::authorizationStateClosed>()));
+  callback_->on_closed();
+  dec_stop_cnt();
+}
+
+void Td::dec_stop_cnt() {
+  stop_cnt_--;
+  if (stop_cnt_ == 0) {
+    stop();
+  }
+}
+
+void Td::inc_request_actor_refcnt() {
+  request_actor_refcnt_++;
+}
+
+void Td::dec_request_actor_refcnt() {
+  request_actor_refcnt_--;
+  if (request_actor_refcnt_ == 0) {
+    LOG(WARNING) << "no request actors";
+    clear();
+    dec_actor_refcnt();  // remove guard
+  }
+}
+
+void Td::clear_handlers() {
+  result_handlers_.clear();
+}
+
+void Td::clear() {
+  if (close_flag_ >= 2) {
+    return;
+  }
+
+  close_flag_ = 2;
+
+  Timer timer;
+  if (destroy_flag_) {
+    for (auto &option : G()->shared_config().get_options()) {
+      if (!is_internal_config_option(option.first)) {
+        send_update(make_tl_object<td_api::updateOption>(option.first, make_tl_object<td_api::optionValueEmpty>()));
+      }
+    }
+  }
+  LOG(DEBUG) << "Options was cleared " << timer;
+
+  G()->net_query_creator().stop_check();
+  clear_handlers();
+  LOG(DEBUG) << "Handlers was cleared " << timer;
+  G()->net_query_dispatcher().stop();
+  LOG(DEBUG) << "NetQueryDispatcher was stopped " << timer;
+  state_manager_.reset();
+  LOG(DEBUG) << "StateManager was cleared " << timer;
+  while (!pending_alarms_.empty()) {
+    auto it = pending_alarms_.begin();
+    auto alarm_id = it->first;
+    pending_alarms_.erase(it);
+    alarm_timeout_.cancel_timeout(alarm_id);
+  }
+  while (!request_set_.empty()) {
+    uint64 id = *request_set_.begin();
+    if (destroy_flag_) {
+      send_error_impl(id, make_error(401, "Unauthorized"));
+    } else {
+      send_error_impl(id, make_error(500, "Internal Server Error: closing"));
+    }
+  }
+  if (is_online_) {
+    is_online_ = false;
+    alarm_timeout_.cancel_timeout(ONLINE_ALARM_ID);
+  }
+  alarm_timeout_.cancel_timeout(PING_SERVER_ALARM_ID);
+  LOG(DEBUG) << "Requests was answered " << timer;
+
+  // close all pure actors
+  call_manager_.reset();
+  LOG(DEBUG) << "CallManager was cleared " << timer;
+  config_manager_.reset();
+  LOG(DEBUG) << "ConfigManager was cleared " << timer;
+  device_token_manager_.reset();
+  LOG(DEBUG) << "DeviceTokenManager was cleared " << timer;
+  hashtag_hints_.reset();
+  LOG(DEBUG) << "HashtagHints was cleared " << timer;
+  net_stats_manager_.reset();
+  LOG(DEBUG) << "NetStatsManager was cleared " << timer;
+  password_manager_.reset();
+  LOG(DEBUG) << "PasswordManager was cleared " << timer;
+  privacy_manager_.reset();
+  LOG(DEBUG) << "PrivacyManager was cleared " << timer;
+  secret_chats_manager_.reset();
+  LOG(DEBUG) << "SecretChatsManager was cleared " << timer;
+  storage_manager_.reset();
+  LOG(DEBUG) << "StorageManager was cleared " << timer;
+  top_dialog_manager_.reset();
+  LOG(DEBUG) << "TopDialogManager was cleared " << timer;
+
+  G()->set_connection_creator(ActorOwn<ConnectionCreator>());
+  LOG(DEBUG) << "ConnectionCreator was cleared " << timer;
+
+  // clear actors which are unique pointers
+  animations_manager_actor_.reset();
+  LOG(DEBUG) << "AnimationsManager actor was cleared " << timer;
+  auth_manager_actor_.reset();
+  LOG(DEBUG) << "AuthManager actor was cleared " << timer;
+  change_phone_number_manager_actor_.reset();
+  LOG(DEBUG) << "ChangePhoneNumberManager actor was cleared " << timer;
+  contacts_manager_actor_.reset();
+  LOG(DEBUG) << "ContactsManager actor was cleared " << timer;
+  file_manager_actor_.reset();
+  LOG(DEBUG) << "FileManager actor was cleared " << timer;
+  inline_queries_manager_actor_.reset();
+  LOG(DEBUG) << "InlineQueriesManager actor was cleared " << timer;
+  messages_manager_actor_.reset();  // TODO: Stop silent
+  LOG(DEBUG) << "MessagesManager actor was cleared " << timer;
+  stickers_manager_actor_.reset();
+  LOG(DEBUG) << "StickersManager actor was cleared " << timer;
+  updates_manager_actor_.reset();
+  LOG(DEBUG) << "UpdatesManager actor was cleared " << timer;
+  web_pages_manager_actor_.reset();
+  LOG(DEBUG) << "WebPagesManager actor was cleared " << timer;
+}
+
+void Td::close() {
+  close_impl(false);
+}
+
+void Td::destroy() {
+  close_impl(true);
+}
+
+void Td::close_impl(bool destroy_flag) {
+  destroy_flag_ |= destroy_flag;
+  if (close_flag_) {
+    return;
+  }
+  if (state_ == State::WaitParameters) {
+    return on_closed();
+  }
+  if (state_ == State::Decrypt) {
+    if (destroy_flag) {
+      TdDb::destroy(parameters_);
+    }
+    state_ = State::Close;
+    close_flag_ = 4;
+    return dec_actor_refcnt();
+  }
+  state_ = State::Close;
+  close_flag_ = 1;
+  G()->set_close_flag();
+  send_closure(auth_manager_actor_, &AuthManager::on_closing);
+  LOG(WARNING) << "Close " << tag("destroy", destroy_flag);
+
+  // wait till all request_actors will stop.
+  request_actors_.clear();
+  G()->td_db()->flush_all();
+  send_closure_later(actor_id(this), &Td::dec_request_actor_refcnt);  // remove guard
+}
+
+class Td::DownloadFileCallback : public FileManager::DownloadCallback {
+ public:
+  void on_progress(FileId file_id) override {
+  }
+
+  void on_download_ok(FileId file_id) override {
+  }
+
+  void on_download_error(FileId file_id, Status error) override {
+  }
+};
+
+class Td::UploadFileCallback : public FileManager::UploadCallback {
+ public:
+  void on_progress(FileId file_id) override {
+  }
+
+  void on_upload_ok(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) override {
+    // cancel file upload of the file to allow next upload with the same file to succeed
+    send_closure(G()->file_manager(), &FileManager::upload, file_id, nullptr, 0, 0);
+  }
+
+  void on_upload_encrypted_ok(FileId file_id, tl_object_ptr<telegram_api::InputEncryptedFile> input_file) override {
+    // cancel file upload of the file to allow next upload with the same file to succeed
+    send_closure(G()->file_manager(), &FileManager::upload, file_id, nullptr, 0, 0);
+  }
+
+  void on_upload_error(FileId file_id, Status error) override {
+  }
+};
+
+int VERBOSITY_NAME(td_init) = VERBOSITY_NAME(DEBUG) + 3;
+
+Status Td::init(DbKey key) {
+  auto current_scheduler_id = Scheduler::instance()->sched_id();
+  auto scheduler_count = Scheduler::instance()->sched_count();
+
+  VLOG(td_init) << "Begin to init database";
+  TdDb::Events events;
+  TRY_RESULT(td_db,
+             TdDb::open(min(current_scheduler_id + 1, scheduler_count - 1), parameters_, std::move(key), events));
+  LOG(INFO) << "Successfully inited database in " << tag("database_directory", parameters_.database_directory)
+            << " and " << tag("files_directory", parameters_.files_directory);
+  G()->init(parameters_, actor_id(this), std::move(td_db)).ensure();
+
+  // Init all managers and actors
+  VLOG(td_init) << "Create StateManager";
+  class StateManagerCallback : public StateManager::Callback {
+   public:
+    explicit StateManagerCallback(ActorShared<Td> td) : td_(std::move(td)) {
+    }
+    bool on_state(StateManager::State state) override {
+      send_closure(td_, &Td::on_connection_state_changed, state);
+      return td_.is_alive();
+    }
+
+   private:
+    ActorShared<Td> td_;
+  };
+  state_manager_ = create_actor<StateManager>("State manager");
+  send_closure(state_manager_, &StateManager::add_callback, make_unique<StateManagerCallback>(create_reference()));
+  G()->set_state_manager(state_manager_.get());
+  connection_state_ = StateManager::State::Empty;
+
+  VLOG(td_init) << "Create ConnectionCreator";
+  {
+    auto connection_creator = create_actor<ConnectionCreator>("ConnectionCreator", create_reference());
+    auto net_stats_manager = create_actor<NetStatsManager>("NetStatsManager", create_reference());
+
+    // How else could I let two actor know about each other, without quite complex async logic?
+    auto net_stats_manager_ptr = net_stats_manager->get_actor_unsafe();
+    net_stats_manager_ptr->init();
+    connection_creator->get_actor_unsafe()->set_net_stats_callback(net_stats_manager_ptr->get_common_stats_callback(),
+                                                                   net_stats_manager_ptr->get_media_stats_callback());
+    G()->set_net_stats_file_callbacks(net_stats_manager_ptr->get_file_stats_callbacks());
+
+    G()->set_connection_creator(std::move(connection_creator));
+    net_stats_manager_ = std::move(net_stats_manager);
+  }
+
+  VLOG(td_init) << "Create TempAuthKeyWatchdog";
+  auto temp_auth_key_watchdog = create_actor<TempAuthKeyWatchdog>("TempAuthKeyWatchdog");
+  G()->set_temp_auth_key_watchdog(std::move(temp_auth_key_watchdog));
+
+  VLOG(td_init) << "Create ConfigManager and ConfigShared";
+  class ConfigSharedCallback : public ConfigShared::Callback {
+   public:
+    void on_option_updated(const string &name) override {
+      send_closure(G()->td(), &Td::on_config_option_updated, name);
+    }
+  };
+  send_closure(
+      actor_id(this), &Td::send_update,
+      make_tl_object<td_api::updateOption>("version", make_tl_object<td_api::optionValueString>(TDLIB_VERSION)));
+
+  G()->set_shared_config(
+      std::make_unique<ConfigShared>(G()->td_db()->get_config_pmc(), std::make_unique<ConfigSharedCallback>()));
+  config_manager_ = create_actor<ConfigManager>("ConfigManager", create_reference());
+  G()->set_config_manager(config_manager_.get());
+
+  VLOG(td_init) << "Create NetQueryDispatcher";
+  auto net_query_dispatcher = std::make_unique<NetQueryDispatcher>([&] { return create_reference(); });
+  G()->set_net_query_dispatcher(std::move(net_query_dispatcher));
+
+  VLOG(td_init) << "Create AuthManager";
+  auth_manager_ = std::make_unique<AuthManager>(parameters_.api_id, parameters_.api_hash, create_reference());
+  auth_manager_actor_ = register_actor("AuthManager", auth_manager_.get());
+
+  VLOG(td_init) << "Create FileManager";
+  download_file_callback_ = std::make_shared<DownloadFileCallback>();
+  upload_file_callback_ = std::make_shared<UploadFileCallback>();
+
+  class FileManagerContext : public FileManager::Context {
+   public:
+    explicit FileManagerContext(Td *td) : td_(td) {
+    }
+    void on_new_file(int64 size) final {
+      send_closure(G()->storage_manager(), &StorageManager::on_new_file, size);
+    }
+    void on_file_updated(FileId file_id) final {
+      send_closure(G()->td(), &Td::send_update,
+                   make_tl_object<td_api::updateFile>(td_->file_manager_->get_file_object(file_id)));
+    }
+    ActorShared<> create_reference() final {
+      return td_->create_reference();
+    }
+
+   private:
+    Td *td_;
+  };
+  file_manager_ = std::make_unique<FileManager>(std::make_unique<FileManagerContext>(this));
+  file_manager_actor_ = register_actor("FileManager", file_manager_.get());
+  file_manager_->init_actor();
+  G()->set_file_manager(file_manager_actor_.get());
+
+  VLOG(td_init) << "Create Managers";
+  audios_manager_ = make_unique<AudiosManager>(this);
+  callback_queries_manager_ = make_unique<CallbackQueriesManager>(this);
+  documents_manager_ = make_unique<DocumentsManager>(this);
+  video_notes_manager_ = make_unique<VideoNotesManager>(this);
+  videos_manager_ = make_unique<VideosManager>(this);
+  voice_notes_manager_ = make_unique<VoiceNotesManager>(this);
+
+  animations_manager_ = std::make_unique<AnimationsManager>(this, create_reference());
+  animations_manager_actor_ = register_actor("AnimationsManager", animations_manager_.get());
+  G()->set_animations_manager(animations_manager_actor_.get());
+  change_phone_number_manager_ = std::make_unique<ChangePhoneNumberManager>(create_reference());
+  change_phone_number_manager_actor_ = register_actor("ChangePhoneNumberManager", change_phone_number_manager_.get());
+  contacts_manager_ = std::make_unique<ContactsManager>(this, create_reference());
+  contacts_manager_actor_ = register_actor("ContactsManager", contacts_manager_.get());
+  G()->set_contacts_manager(contacts_manager_actor_.get());
+  inline_queries_manager_ = std::make_unique<InlineQueriesManager>(this, create_reference());
+  inline_queries_manager_actor_ = register_actor("InlineQueriesManager", inline_queries_manager_.get());
+  messages_manager_ = std::make_unique<MessagesManager>(this, create_reference());
+  messages_manager_actor_ = register_actor("MessagesManager", messages_manager_.get());
+  G()->set_messages_manager(messages_manager_actor_.get());
+  stickers_manager_ = std::make_unique<StickersManager>(this, create_reference());
+  stickers_manager_actor_ = register_actor("StickersManager", stickers_manager_.get());
+  G()->set_stickers_manager(stickers_manager_actor_.get());
+  updates_manager_ = std::make_unique<UpdatesManager>(this, create_reference());
+  updates_manager_actor_ = register_actor("UpdatesManager", updates_manager_.get());
+  G()->set_updates_manager(updates_manager_actor_.get());
+  web_pages_manager_ = std::make_unique<WebPagesManager>(this, create_reference());
+  web_pages_manager_actor_ = register_actor("WebPagesManager", web_pages_manager_.get());
+  G()->set_web_pages_manager(web_pages_manager_actor_.get());
+
+  call_manager_ = create_actor<CallManager>("CallManager", create_reference());
+  G()->set_call_manager(call_manager_.get());
+  device_token_manager_ = create_actor<DeviceTokenManager>("DeviceTokenManager", create_reference());
+  hashtag_hints_ = create_actor<HashtagHints>("HashtagHints", "text", create_reference());
+  password_manager_ = create_actor<PasswordManager>("PasswordManager", create_reference());
+  privacy_manager_ = create_actor<PrivacyManager>("PrivacyManager", create_reference());
+  secret_chats_manager_ = create_actor<SecretChatsManager>("SecretChatsManager", create_reference());
+  G()->set_secret_chats_manager(secret_chats_manager_.get());
+  storage_manager_ = create_actor<StorageManager>("StorageManager", create_reference(),
+                                                  min(current_scheduler_id + 2, scheduler_count - 1));
+  G()->set_storage_manager(storage_manager_.get());
+  top_dialog_manager_ = create_actor<TopDialogManager>("TopDialogManager", create_reference());
+  G()->set_top_dialog_manager(top_dialog_manager_.get());
+
+  VLOG(td_init) << "Send binlog events";
+  for (auto &event : events.user_events) {
+    contacts_manager_->on_binlog_user_event(std::move(event));
+  }
+
+  for (auto &event : events.channel_events) {
+    contacts_manager_->on_binlog_channel_event(std::move(event));
+  }
+
+  // chats may contain links to channels, so should be inited after
+  for (auto &event : events.chat_events) {
+    contacts_manager_->on_binlog_chat_event(std::move(event));
+  }
+
+  for (auto &event : events.secret_chat_events) {
+    contacts_manager_->on_binlog_secret_chat_event(std::move(event));
+  }
+
+  for (auto &event : events.web_page_events) {
+    web_pages_manager_->on_binlog_web_page_event(std::move(event));
+  }
+
+  // Send binlog events to managers
+  //
+  // 1. Actors must receive all binlog events before other queries.
+  //
+  // -- All actors have one "entry point". So there is only one way to send query to them. So all queries are ordered
+  // for  each Actor.
+  //
+  //
+  // 2. An actor must not make some decisions before all binlog events are processed.
+  // For example, SecretChatActor must not send RequestKey, before it receives logevent with RequestKey and understands
+  // that RequestKey was already sent.
+  //
+  // -- G()->wait_binlog_replay_finish(Promise<>);
+  //
+  // 3. During replay of binlog some queries may be sent to other actors. They shouldn't process such events before all
+  // their binlog events are processed. So actor may receive some old queries. It must be in it's actual state in
+  // orded to handle them properly.
+  //
+  // -- Use send_closure_later, so actors don't even start process binlog events, before all binlog events are sent
+
+  for (auto &event : events.to_secret_chats_manager) {
+    send_closure_later(secret_chats_manager_, &SecretChatsManager::replay_binlog_event, std::move(event));
+  }
+
+  send_closure_later(messages_manager_actor_, &MessagesManager::on_binlog_events,
+                     std::move(events.to_messages_manager));
+
+  // NB: be very careful. This notification may be received before all binlog events are.
+  G()->on_binlog_replay_finish();
+  send_closure(secret_chats_manager_, &SecretChatsManager::binlog_replay_finish);
+
+  VLOG(td_init) << "Ping datacenter";
+  if (!auth_manager_->is_authorized()) {
+    create_handler<GetNearestDcQuery>(Promise<string>())->send();
+  } else {
+    updates_manager_->get_difference("init");
+  }
+
+  state_ = State::Run;
+  return Status::OK();
+}
+
+void Td::send_update(tl_object_ptr<td_api::Update> &&object) {
+  switch (object->get_id()) {
+    case td_api::updateFavoriteStickers::ID:
+    case td_api::updateInstalledStickerSets::ID:
+    case td_api::updateRecentStickers::ID:
+    case td_api::updateSavedAnimations::ID:
+    case td_api::updateUserStatus::ID:
+      VLOG(td_requests) << "Sending update: " << oneline(to_string(object));
+      break;
+    case td_api::updateTrendingStickerSets::ID:
+      VLOG(td_requests) << "Sending update: updateTrendingStickerSets { ... }";
+      break;
+    default:
+      VLOG(td_requests) << "Sending update: " << to_string(object);
+  }
+
+  callback_->on_result(0, std::move(object));
+}
+
+void Td::send_result(uint64 id, tl_object_ptr<td_api::Object> object) {
+  if (id == 0) {
+    LOG(ERROR) << "Sending " << to_string(object) << " through send_result";
+    return;
+  }
+
+  auto it = request_set_.find(id);
+  if (it != request_set_.end()) {
+    request_set_.erase(it);
+    VLOG(td_requests) << "Sending result for request " << id << ": " << to_string(object);
+    if (object == nullptr) {
+      object = make_tl_object<td_api::error>(404, "Not Found");
+    }
+    callback_->on_result(id, std::move(object));
+  }
+}
+
+void Td::send_error_impl(uint64 id, tl_object_ptr<td_api::error> error) {
+  CHECK(id != 0);
+  CHECK(callback_ != nullptr);
+  CHECK(error != nullptr);
+  auto it = request_set_.find(id);
+  if (it != request_set_.end()) {
+    request_set_.erase(it);
+    VLOG(td_requests) << "Sending error for request " << id << ": " << oneline(to_string(error));
+    callback_->on_error(id, std::move(error));
+  }
+}
+
+void Td::send_error(uint64 id, Status error) {
+  send_error_impl(id, make_tl_object<td_api::error>(error.code(), error.message().str()));
+  error.ignore();
+}
+
+void Td::send_error_raw(uint64 id, int32 code, CSlice error) {
+  send_closure(actor_id(this), &Td::send_error_impl, id, make_error(code, error));
+}
+
+void Td::answer_ok_query(uint64 id, Status status) {
+  if (status.is_error()) {
+    send_closure(actor_id(this), &Td::send_error, id, std::move(status));
+  } else {
+    send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::ok>());
+  }
+}
+
+#define CLEAN_INPUT_STRING(field_name)                                  \
+  if (!clean_input_string(field_name)) {                                \
+    return send_error_raw(id, 400, "Strings must be encoded in UTF-8"); \
+  }
+#define CHECK_AUTH()                                \
+  if (!auth_manager_->is_authorized()) {            \
+    return send_error_raw(id, 401, "Unauthorized"); \
+  }
+#define CHECK_IS_BOT()                                              \
+  if (!auth_manager_->is_bot()) {                                   \
+    return send_error_raw(id, 400, "Only bots can use the method"); \
+  }
+#define CHECK_IS_USER()                                                     \
+  if (auth_manager_->is_bot()) {                                            \
+    return send_error_raw(id, 400, "The method is not available for bots"); \
+  }
+
+#define CREATE_NO_ARGS_REQUEST(name)                                       \
+  auto slot_id = request_actors_.create(ActorOwn<>(), RequestActorIdType); \
+  inc_request_actor_refcnt();                                              \
+  *request_actors_.get(slot_id) = create_actor<name>(#name, actor_shared(this, slot_id), id);
+#define CREATE_REQUEST(name, ...)                                          \
+  auto slot_id = request_actors_.create(ActorOwn<>(), RequestActorIdType); \
+  inc_request_actor_refcnt();                                              \
+  *request_actors_.get(slot_id) = create_actor<name>(#name, actor_shared(this, slot_id), id, __VA_ARGS__);
+#define CREATE_REQUEST_PROMISE(name) \
+  auto name = create_request_promise<std::decay_t<decltype(request)>::ReturnType>(id);
+
+Status Td::fix_parameters(TdParameters &parameters) {
+  if (parameters.database_directory.empty()) {
+    VLOG(td_init) << "Fix database_directory";
+    parameters.database_directory = ".";
+  }
+  if (parameters.files_directory.empty()) {
+    VLOG(td_init) << "Fix files_directory";
+    parameters.files_directory = parameters.database_directory;
+  }
+  if (parameters.use_message_db) {
+    VLOG(td_init) << "Fix use_chat_info_db";
+    parameters.use_chat_info_db = true;
+  }
+  if (parameters.use_chat_info_db) {
+    VLOG(td_init) << "Fix use_file_db";
+    parameters.use_file_db = true;
+  }
+  if (parameters.api_id <= 0) {
+    VLOG(td_init) << "Invalid api_id";
+    return Status::Error(400, "Valid api_id must be provided. Can be obtained at https://my.telegram.org");
+  }
+  if (parameters.api_hash.empty()) {
+    VLOG(td_init) << "Invalid api_hash";
+    return Status::Error(400, "Valid api_hash must be provided. Can be obtained at https://my.telegram.org");
+  }
+
+  auto prepare_dir = [](string dir) -> Result<string> {
+    CHECK(!dir.empty());
+    if (dir.back() != TD_DIR_SLASH) {
+      dir += TD_DIR_SLASH;
+    }
+    TRY_STATUS(mkpath(dir, 0750));
+    TRY_RESULT(real_dir, realpath(dir, true));
+    if (dir.back() != TD_DIR_SLASH) {
+      dir += TD_DIR_SLASH;
+    }
+    return real_dir;
+  };
+
+  auto r_database_directory = prepare_dir(parameters.database_directory);
+  if (r_database_directory.is_error()) {
+    VLOG(td_init) << "Invalid database_directory";
+    return Status::Error(400, PSLICE() << "Can't init database in the directory \"" << parameters.database_directory
+                                       << "\": " << r_database_directory.error());
+  }
+  parameters.database_directory = r_database_directory.move_as_ok();
+  auto r_files_directory = prepare_dir(parameters.files_directory);
+  if (r_files_directory.is_error()) {
+    VLOG(td_init) << "Invalid files_directory";
+    return Status::Error(400, PSLICE() << "Can't init files directory \"" << parameters.files_directory
+                                       << "\": " << r_files_directory.error());
+  }
+  parameters.files_directory = r_files_directory.move_as_ok();
+
+  return Status::OK();
+}
+
+Status Td::set_parameters(td_api::object_ptr<td_api::tdlibParameters> parameters) {
+  VLOG(td_init) << "Begin to set TDLib parameters";
+  if (parameters == nullptr) {
+    VLOG(td_init) << "Empty parameters";
+    return Status::Error(400, "Parameters aren't specified");
+  }
+
+  if (!clean_input_string(parameters->api_hash_) && !clean_input_string(parameters->system_language_code_) &&
+      !clean_input_string(parameters->device_model_) && !clean_input_string(parameters->system_version_) &&
+      !clean_input_string(parameters->application_version_)) {
+    VLOG(td_init) << "Wrong string encoding";
+    return Status::Error(400, "Strings must be encoded in UTF-8");
+  }
+
+  parameters_.use_test_dc = parameters->use_test_dc_;
+  parameters_.database_directory = parameters->database_directory_;
+  parameters_.files_directory = parameters->files_directory_;
+  parameters_.api_id = parameters->api_id_;
+  parameters_.api_hash = parameters->api_hash_;
+  parameters_.use_file_db = parameters->use_file_database_;
+  parameters_.enable_storage_optimizer = parameters->enable_storage_optimizer_;
+  parameters_.ignore_file_names = parameters->ignore_file_names_;
+  parameters_.use_secret_chats = parameters->use_secret_chats_;
+  parameters_.use_chat_info_db = parameters->use_chat_info_database_;
+  parameters_.use_message_db = parameters->use_message_database_;
+
+  VLOG(td_init) << "Fix parameters...";
+  TRY_STATUS(fix_parameters(parameters_));
+  VLOG(td_init) << "Check binlog encryption...";
+  TRY_RESULT(encryption_info, TdDb::check_encryption(parameters_));
+  encryption_info_ = std::move(encryption_info);
+
+  VLOG(td_init) << "Init alarm multitimeout...";
+  alarm_timeout_.set_callback(on_alarm_timeout_callback);
+  alarm_timeout_.set_callback_data(static_cast<void *>(this));
+
+  VLOG(td_init) << "Create Global";
+  set_context(std::make_shared<Global>());
+  inc_request_actor_refcnt();  // guard
+  inc_actor_refcnt();          // guard
+
+  VLOG(td_init) << "Create MtprotoHeader";
+  MtprotoHeader::Options options;
+  options.api_id = parameters->api_id_;
+  options.system_language_code = trim(parameters->system_language_code_);
+  options.device_model = trim(parameters->device_model_);
+  options.system_version = trim(parameters->system_version_);
+  options.application_version = trim(parameters->application_version_);
+  if (options.system_language_code.empty()) {
+    return Status::Error(400, "System language code must be non-empty");
+  }
+  if (options.device_model.empty()) {
+    return Status::Error(400, "Device model must be non-empty");
+  }
+  if (options.system_version.empty()) {
+    return Status::Error(400, "System version must be non-empty");
+  }
+  if (options.application_version.empty()) {
+    return Status::Error(400, "Application version must be non-empty");
+  }
+  if (options.api_id != 21724) {
+    options.application_version += ", TDLib ";
+    options.application_version += TDLIB_VERSION;
+  }
+  G()->set_mtproto_header(std::make_unique<MtprotoHeader>(options));
+
+  state_ = State::Decrypt;
+  VLOG(td_init) << "Send authorizationStateWaitEncryptionKey";
+  send_closure(actor_id(this), &Td::send_update,
+               td_api::make_object<td_api::updateAuthorizationState>(
+                   td_api::make_object<td_api::authorizationStateWaitEncryptionKey>(encryption_info_.is_encrypted)));
+  VLOG(td_init) << "Finish set parameters";
+  return Status::OK();
+}
+
+void Td::on_request(uint64 id, const td_api::setTdlibParameters &request) {
+  send_error_raw(id, 400, "Unexpected setTdlibParameters");
+}
+
+void Td::on_request(uint64 id, const td_api::checkDatabaseEncryptionKey &request) {
+  send_error_raw(id, 400, "Unexpected checkDatabaseEncryptionKey");
+}
+
+void Td::on_request(uint64 id, td_api::setDatabaseEncryptionKey &request) {
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(make_tl_object<td_api::ok>());
+    }
+  });
+  G()->td_db()->get_binlog()->change_key(as_db_key(std::move(request.new_encryption_key_)), std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, const td_api::getAuthorizationState &request) {
+  send_closure(auth_manager_actor_, &AuthManager::get_state, id);
+}
+
+void Td::on_request(uint64 id, td_api::setAuthenticationPhoneNumber &request) {
+  CLEAN_INPUT_STRING(request.phone_number_);
+  send_closure(auth_manager_actor_, &AuthManager::set_phone_number, id, std::move(request.phone_number_),
+               request.allow_flash_call_, request.is_current_phone_number_);
+}
+
+void Td::on_request(uint64 id, const td_api::resendAuthenticationCode &request) {
+  send_closure(auth_manager_actor_, &AuthManager::resend_authentication_code, id);
+}
+
+void Td::on_request(uint64 id, td_api::checkAuthenticationCode &request) {
+  CLEAN_INPUT_STRING(request.code_);
+  CLEAN_INPUT_STRING(request.first_name_);
+  CLEAN_INPUT_STRING(request.last_name_);
+  send_closure(auth_manager_actor_, &AuthManager::check_code, id, std::move(request.code_),
+               std::move(request.first_name_), std::move(request.last_name_));
+}
+
+void Td::on_request(uint64 id, td_api::checkAuthenticationPassword &request) {
+  CLEAN_INPUT_STRING(request.password_);
+  send_closure(auth_manager_actor_, &AuthManager::check_password, id, std::move(request.password_));
+}
+
+void Td::on_request(uint64 id, const td_api::requestAuthenticationPasswordRecovery &request) {
+  send_closure(auth_manager_actor_, &AuthManager::request_password_recovery, id);
+}
+
+void Td::on_request(uint64 id, td_api::recoverAuthenticationPassword &request) {
+  CLEAN_INPUT_STRING(request.recovery_code_);
+  send_closure(auth_manager_actor_, &AuthManager::recover_password, id, std::move(request.recovery_code_));
+}
+
+void Td::on_request(uint64 id, const td_api::logOut &request) {
+  // will call Td::destroy later
+  send_closure(auth_manager_actor_, &AuthManager::logout, id);
+}
+
+void Td::on_request(uint64 id, const td_api::close &request) {
+  close();
+  send_closure(actor_id(this), &Td::send_result, id, td_api::make_object<td_api::ok>());
+}
+
+void Td::on_request(uint64 id, const td_api::destroy &request) {
+  destroy();
+  send_closure(actor_id(this), &Td::send_result, id, td_api::make_object<td_api::ok>());
+}
+
+void Td::on_request(uint64 id, td_api::checkAuthenticationBotToken &request) {
+  CLEAN_INPUT_STRING(request.token_);
+  send_closure(auth_manager_actor_, &AuthManager::check_bot_token, id, std::move(request.token_));
+}
+
+void Td::on_request(uint64 id, td_api::getPasswordState &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST_PROMISE(promise);
+  send_closure(password_manager_, &PasswordManager::get_state, std::move(promise));
+}
+
+void Td::on_request(uint64 id, td_api::setPassword &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.old_password_);
+  CLEAN_INPUT_STRING(request.new_password_);
+  CLEAN_INPUT_STRING(request.new_hint_);
+  CLEAN_INPUT_STRING(request.new_recovery_email_address_);
+  CREATE_REQUEST_PROMISE(promise);
+  send_closure(password_manager_, &PasswordManager::set_password, std::move(request.old_password_),
+               std::move(request.new_password_), std::move(request.new_hint_), request.set_recovery_email_address_,
+               std::move(request.new_recovery_email_address_), std::move(promise));
+}
+
+void Td::on_request(uint64 id, td_api::setRecoveryEmailAddress &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.password_);
+  CLEAN_INPUT_STRING(request.new_recovery_email_address_);
+  CREATE_REQUEST_PROMISE(promise);
+  send_closure(password_manager_, &PasswordManager::set_recovery_email_address, std::move(request.password_),
+               std::move(request.new_recovery_email_address_), std::move(promise));
+}
+
+void Td::on_request(uint64 id, td_api::getRecoveryEmailAddress &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.password_);
+  CREATE_REQUEST_PROMISE(promise);
+  send_closure(password_manager_, &PasswordManager::get_recovery_email_address, std::move(request.password_),
+               std::move(promise));
+}
+
+void Td::on_request(uint64 id, td_api::requestPasswordRecovery &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST_PROMISE(promise);
+  send_closure(password_manager_, &PasswordManager::request_password_recovery, std::move(promise));
+}
+
+void Td::on_request(uint64 id, td_api::recoverPassword &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.recovery_code_);
+  CREATE_REQUEST_PROMISE(promise);
+  send_closure(password_manager_, &PasswordManager::recover_password, std::move(request.recovery_code_),
+               std::move(promise));
+}
+
+void Td::on_request(uint64 id, td_api::getTemporaryPasswordState &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST_PROMISE(promise);
+  send_closure(password_manager_, &PasswordManager::get_temp_password_state, std::move(promise));
+}
+
+void Td::on_request(uint64 id, td_api::createTemporaryPassword &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.password_);
+  CREATE_REQUEST_PROMISE(promise);
+  send_closure(password_manager_, &PasswordManager::create_temp_password, std::move(request.password_),
+               request.valid_for_, std::move(promise));
+}
+
+void Td::on_request(uint64 id, td_api::processDcUpdate &request) {
+  CREATE_REQUEST_PROMISE(promise);
+  CLEAN_INPUT_STRING(request.dc_);
+  CLEAN_INPUT_STRING(request.addr_);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(make_tl_object<td_api::ok>());
+    }
+  });
+  auto dc_id_raw = to_integer<int32>(request.dc_);
+  if (!DcId::is_valid(dc_id_raw)) {
+    promise.set_error(Status::Error("Invalid dc id"));
+    return;
+  }
+  send_closure(G()->connection_creator(), &ConnectionCreator::on_dc_update, DcId::internal(dc_id_raw), request.addr_,
+               std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, td_api::registerDevice &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  if (request.device_token_ == nullptr) {
+    return send_error_raw(id, 400, "Device token should not be empty");
+  }
+
+  CREATE_REQUEST_PROMISE(promise);
+  send_closure(device_token_manager_, &DeviceTokenManager::register_device, std::move(request.device_token_),
+               std::move(request.other_user_ids_), std::move(promise));
+}
+
+void Td::on_request(uint64 id, td_api::getUserPrivacySettingRules &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST_PROMISE(promise);
+  send_closure(privacy_manager_, &PrivacyManager::get_privacy, std::move(request.setting_), std::move(promise));
+}
+
+void Td::on_request(uint64 id, td_api::setUserPrivacySettingRules &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST_PROMISE(promise);
+  send_closure(privacy_manager_, &PrivacyManager::set_privacy, std::move(request.setting_), std::move(request.rules_),
+               std::move(promise));
+}
+
+void Td::on_request(uint64 id, const td_api::getAccountTtl &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(GetAccountTtlRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::setAccountTtl &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  if (request.ttl_ == nullptr) {
+    return send_error_raw(id, 400, "New account TTL should not be empty");
+  }
+  CREATE_REQUEST(SetAccountTtlRequest, request.ttl_->days_);
+}
+
+void Td::on_request(uint64 id, td_api::deleteAccount &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.reason_);
+  send_closure(auth_manager_actor_, &AuthManager::delete_account, id, request.reason_);
+}
+
+void Td::on_request(uint64 id, td_api::changePhoneNumber &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.phone_number_);
+  change_phone_number_manager_->change_phone_number(id, std::move(request.phone_number_), request.allow_flash_call_,
+                                                    request.is_current_phone_number_);
+}
+
+void Td::on_request(uint64 id, td_api::checkChangePhoneNumberCode &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.code_);
+  change_phone_number_manager_->check_code(id, std::move(request.code_));
+}
+
+void Td::on_request(uint64 id, td_api::resendChangePhoneNumberCode &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  change_phone_number_manager_->resend_authentication_code(id);
+}
+
+void Td::on_request(uint64 id, const td_api::getActiveSessions &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(GetActiveSessionsRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::terminateSession &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(TerminateSessionRequest, request.session_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::terminateAllOtherSessions &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(TerminateAllOtherSessionsRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::getConnectedWebsites &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(GetConnectedWebsitesRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::disconnectWebsite &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(DisconnectWebsiteRequest, request.website_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::disconnectAllWebsites &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(DisconnectAllWebsitesRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::getMe &request) {
+  CHECK_AUTH();
+  CREATE_NO_ARGS_REQUEST(GetMeRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::getUser &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetUserRequest, request.user_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::getUserFullInfo &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetUserFullInfoRequest, request.user_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::getBasicGroup &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetGroupRequest, request.basic_group_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::getBasicGroupFullInfo &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetGroupFullInfoRequest, request.basic_group_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::getSupergroup &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetSupergroupRequest, request.supergroup_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::getSupergroupFullInfo &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetSupergroupFullInfoRequest, request.supergroup_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::getSecretChat &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetSecretChatRequest, request.secret_chat_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::getChat &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetChatRequest, request.chat_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::getMessage &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetMessageRequest, request.chat_id_, request.message_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::getRepliedMessage &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetRepliedMessageRequest, request.chat_id_, request.message_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::getChatPinnedMessage &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetChatPinnedMessageRequest, request.chat_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::getMessages &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetMessagesRequest, request.chat_id_, request.message_ids_);
+}
+
+void Td::on_request(uint64 id, const td_api::getPublicMessageLink &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetPublicMessageLinkRequest, request.chat_id_, request.message_id_, request.for_album_);
+}
+
+void Td::on_request(uint64 id, const td_api::getFile &request) {
+  CHECK_AUTH();
+  send_closure(actor_id(this), &Td::send_result, id, file_manager_->get_file_object(FileId(request.file_id_, 0)));
+}
+
+void Td::on_request(uint64 id, td_api::getRemoteFile &request) {
+  CHECK_AUTH();
+  CLEAN_INPUT_STRING(request.remote_file_id_);
+  auto r_file_id = file_manager_->from_persistent_id(
+      request.remote_file_id_, request.file_type_ == nullptr ? FileType::Temp : from_td_api(*request.file_type_));
+  if (r_file_id.is_error()) {
+    auto error = r_file_id.move_as_error();
+    send_closure(actor_id(this), &Td::send_error, id, std::move(error));
+  } else {
+    send_closure(actor_id(this), &Td::send_result, id, file_manager_->get_file_object(r_file_id.ok()));
+  }
+}
+
+void Td::on_request(uint64 id, td_api::getStorageStatistics &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<FileStats> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(result.ok().as_td_api());
+    }
+  });
+  send_closure(storage_manager_, &StorageManager::get_storage_stats, request.chat_limit_, std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, td_api::getStorageStatisticsFast &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<FileStatsFast> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(result.ok().as_td_api());
+    }
+  });
+  send_closure(storage_manager_, &StorageManager::get_storage_stats_fast, std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, td_api::optimizeStorage &request) {
+  CHECK_AUTH();
+  std::vector<FileType> file_types;
+  for (auto &file_type : request.file_types_) {
+    if (file_type == nullptr) {
+      return send_error_raw(id, 400, "File type should not be empty");
+    }
+
+    file_types.push_back(from_td_api(*file_type));
+  }
+  std::vector<DialogId> owner_dialog_ids;
+  for (auto chat_id : request.chat_ids_) {
+    DialogId dialog_id(chat_id);
+    if (!dialog_id.is_valid() && dialog_id != DialogId()) {
+      return send_error_raw(id, 400, "Wrong chat id");
+    }
+    owner_dialog_ids.push_back(dialog_id);
+  }
+  std::vector<DialogId> exclude_owner_dialog_ids;
+  for (auto chat_id : request.exclude_chat_ids_) {
+    DialogId dialog_id(chat_id);
+    if (!dialog_id.is_valid() && dialog_id != DialogId()) {
+      return send_error_raw(id, 400, "Wrong chat id");
+    }
+    exclude_owner_dialog_ids.push_back(dialog_id);
+  }
+  FileGcParameters parameters(request.size_, request.ttl_, request.count_, request.immunity_delay_,
+                              std::move(file_types), std::move(owner_dialog_ids), std::move(exclude_owner_dialog_ids),
+                              request.chat_limit_);
+
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<FileStats> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(result.ok().as_td_api());
+    }
+  });
+  send_closure(storage_manager_, &StorageManager::run_gc, std::move(parameters), std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, td_api::getNetworkStatistics &request) {
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<NetworkStats> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(result.ok().as_td_api());
+    }
+  });
+  send_closure(net_stats_manager_, &NetStatsManager::get_network_stats, request.only_current_,
+               std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, td_api::resetNetworkStatistics &request) {
+  CREATE_REQUEST_PROMISE(promise);
+  send_closure(net_stats_manager_, &NetStatsManager::reset_network_stats);
+  promise.set_value(make_tl_object<td_api::ok>());
+}
+
+void Td::on_request(uint64 id, td_api::addNetworkStatistics &request) {
+  CREATE_REQUEST_PROMISE(promise);
+  if (request.entry_ == nullptr) {
+    return send_error_raw(id, 400, "Network statistics entry should not be empty");
+  }
+
+  NetworkStatsEntry entry;
+  switch (request.entry_->get_id()) {
+    case td_api::networkStatisticsEntryFile::ID: {
+      auto file_entry = move_tl_object_as<td_api::networkStatisticsEntryFile>(request.entry_);
+      entry.is_call = false;
+      if (file_entry->file_type_ != nullptr) {
+        entry.file_type = from_td_api(*file_entry->file_type_);
+      }
+      entry.net_type = from_td_api(file_entry->network_type_);
+      entry.rx = file_entry->received_bytes_;
+      entry.tx = file_entry->sent_bytes_;
+      break;
+    }
+    case td_api::networkStatisticsEntryCall::ID: {
+      auto call_entry = move_tl_object_as<td_api::networkStatisticsEntryCall>(request.entry_);
+      entry.is_call = true;
+      entry.net_type = from_td_api(call_entry->network_type_);
+      entry.rx = call_entry->received_bytes_;
+      entry.tx = call_entry->sent_bytes_;
+      entry.duration = call_entry->duration_;
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+
+  if (entry.net_type == NetType::None) {
+    return send_error_raw(id, 400, "Network statistics entry can't be increased for NetworkTypeNone");
+  }
+  if (entry.rx > (1ll << 40) || entry.rx < 0) {
+    return send_error_raw(id, 400, "Wrong received bytes value");
+  }
+  if (entry.tx > (1ll << 40) || entry.tx < 0) {
+    return send_error_raw(id, 400, "Wrong sent bytes value");
+  }
+  if (entry.count > (1 << 30) || entry.count < 0) {
+    return send_error_raw(id, 400, "Wrong count value");
+  }
+  if (entry.duration > (1 << 30) || entry.duration < 0) {
+    return send_error_raw(id, 400, "Wrong duration value");
+  }
+
+  send_closure(net_stats_manager_, &NetStatsManager::add_network_stats, entry);
+  send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::ok>());
+}
+
+void Td::on_request(uint64 id, td_api::setNetworkType &request) {
+  CREATE_REQUEST_PROMISE(promise);
+  send_closure(state_manager_, &StateManager::on_network, from_td_api(request.type_));
+  promise.set_value(make_tl_object<td_api::ok>());
+}
+
+void Td::on_request(uint64 id, td_api::getTopChats &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST_PROMISE(promise);
+  if (request.category_ == nullptr) {
+    promise.set_error(Status::Error(400, "Top chat category should not be empty"));
+    return;
+  }
+  if (request.limit_ <= 0) {
+    promise.set_error(Status::Error(400, "Limit must be positive"));
+    return;
+  }
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<vector<DialogId>> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(MessagesManager::get_chats_object(result.ok()));
+    }
+  });
+  send_closure(top_dialog_manager_, &TopDialogManager::get_top_dialogs,
+               top_dialog_category_from_td_api(*request.category_), request.limit_, std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, const td_api::removeTopChat &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  if (request.category_ == nullptr) {
+    return send_error_raw(id, 400, "Top chat category should not be empty");
+  }
+
+  send_closure(top_dialog_manager_, &TopDialogManager::remove_dialog,
+               top_dialog_category_from_td_api(*request.category_), DialogId(request.chat_id_),
+               messages_manager_->get_input_peer(DialogId(request.chat_id_), AccessRights::Read));
+  send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::ok>());
+}
+
+void Td::on_request(uint64 id, const td_api::getChats &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(GetChatsRequest, request.offset_order_, request.offset_chat_id_, request.limit_);
+}
+
+void Td::on_request(uint64 id, td_api::searchPublicChat &request) {
+  CHECK_AUTH();
+  CLEAN_INPUT_STRING(request.username_);
+  CREATE_REQUEST(SearchPublicChatRequest, request.username_);
+}
+
+void Td::on_request(uint64 id, td_api::searchPublicChats &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.query_);
+  CREATE_REQUEST(SearchPublicChatsRequest, request.query_);
+}
+
+void Td::on_request(uint64 id, td_api::searchChats &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.query_);
+  CREATE_REQUEST(SearchChatsRequest, request.query_, request.limit_);
+}
+
+void Td::on_request(uint64 id, td_api::searchChatsOnServer &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.query_);
+  CREATE_REQUEST(SearchChatsOnServerRequest, request.query_, request.limit_);
+}
+
+void Td::on_request(uint64 id, const td_api::getGroupsInCommon &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(GetGroupsInCommonRequest, request.user_id_, request.offset_chat_id_, request.limit_);
+}
+
+void Td::on_request(uint64 id, td_api::checkChatUsername &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.username_);
+  CREATE_REQUEST(CheckChatUsernameRequest, request.chat_id_, std::move(request.username_));
+}
+
+void Td::on_request(uint64 id, const td_api::getCreatedPublicChats &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(GetCreatedPublicChatsRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::addRecentlyFoundChat &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  answer_ok_query(id, messages_manager_->add_recently_found_dialog(DialogId(request.chat_id_)));
+}
+
+void Td::on_request(uint64 id, const td_api::removeRecentlyFoundChat &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  answer_ok_query(id, messages_manager_->remove_recently_found_dialog(DialogId(request.chat_id_)));
+}
+
+void Td::on_request(uint64 id, const td_api::clearRecentlyFoundChats &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  messages_manager_->clear_recently_found_dialogs();
+  send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::ok>());
+}
+
+void Td::on_request(uint64 id, const td_api::openChat &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  answer_ok_query(id, messages_manager_->open_dialog(DialogId(request.chat_id_)));
+}
+
+void Td::on_request(uint64 id, const td_api::closeChat &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  answer_ok_query(id, messages_manager_->close_dialog(DialogId(request.chat_id_)));
+}
+
+void Td::on_request(uint64 id, const td_api::viewMessages &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  answer_ok_query(
+      id, messages_manager_->view_messages(
+              DialogId(request.chat_id_), MessagesManager::get_message_ids(request.message_ids_), request.force_read_));
+}
+
+void Td::on_request(uint64 id, const td_api::openMessageContent &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  answer_ok_query(
+      id, messages_manager_->open_message_content({DialogId(request.chat_id_), MessageId(request.message_id_)}));
+}
+
+void Td::on_request(uint64 id, const td_api::getChatHistory &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(GetChatHistoryRequest, request.chat_id_, request.from_message_id_, request.offset_, request.limit_,
+                 request.only_local_);
+}
+
+void Td::on_request(uint64 id, const td_api::deleteChatHistory &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(DeleteChatHistoryRequest, request.chat_id_, request.remove_from_chat_list_);
+}
+
+void Td::on_request(uint64 id, td_api::searchChatMessages &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.query_);
+  CREATE_REQUEST(SearchChatMessagesRequest, request.chat_id_, std::move(request.query_), request.sender_user_id_,
+                 request.from_message_id_, request.offset_, request.limit_, std::move(request.filter_));
+}
+
+void Td::on_request(uint64 id, td_api::searchSecretMessages &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.query_);
+  CREATE_REQUEST(OfflineSearchMessagesRequest, request.chat_id_, std::move(request.query_), request.from_search_id_,
+                 request.limit_, std::move(request.filter_));
+}
+
+void Td::on_request(uint64 id, td_api::searchMessages &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.query_);
+  CREATE_REQUEST(SearchMessagesRequest, std::move(request.query_), request.offset_date_, request.offset_chat_id_,
+                 request.offset_message_id_, request.limit_);
+}
+
+void Td::on_request(uint64 id, td_api::searchCallMessages &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(SearchCallMessagesRequest, request.from_message_id_, request.limit_, request.only_missed_);
+}
+
+void Td::on_request(uint64 id, const td_api::searchChatRecentLocationMessages &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(SearchChatRecentLocationMessagesRequest, request.chat_id_, request.limit_);
+}
+
+void Td::on_request(uint64 id, const td_api::getActiveLiveLocationMessages &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(GetActiveLiveLocationMessagesRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::getChatMessageByDate &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetChatMessageByDateRequest, request.chat_id_, request.date_);
+}
+
+void Td::on_request(uint64 id, const td_api::deleteMessages &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(DeleteMessagesRequest, request.chat_id_, request.message_ids_, request.revoke_);
+}
+
+void Td::on_request(uint64 id, const td_api::deleteChatMessagesFromUser &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(DeleteChatMessagesFromUserRequest, request.chat_id_, request.user_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::readAllChatMentions &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(ReadAllChatMentionsRequest, request.chat_id_);
+}
+
+void Td::on_request(uint64 id, td_api::sendMessage &request) {
+  CHECK_AUTH();
+
+  DialogId dialog_id(request.chat_id_);
+  auto r_new_message_id = messages_manager_->send_message(
+      dialog_id, MessageId(request.reply_to_message_id_), request.disable_notification_, request.from_background_,
+      std::move(request.reply_markup_), std::move(request.input_message_content_));
+  if (r_new_message_id.is_error()) {
+    return send_closure(actor_id(this), &Td::send_error, id, r_new_message_id.move_as_error());
+  }
+
+  CHECK(r_new_message_id.ok().is_valid());
+  send_closure(actor_id(this), &Td::send_result, id,
+               messages_manager_->get_message_object({dialog_id, r_new_message_id.ok()}));
+}
+
+void Td::on_request(uint64 id, td_api::sendMessageAlbum &request) {
+  CHECK_AUTH();
+
+  DialogId dialog_id(request.chat_id_);
+  auto r_message_ids = messages_manager_->send_message_group(dialog_id, MessageId(request.reply_to_message_id_),
+                                                             request.disable_notification_, request.from_background_,
+                                                             std::move(request.input_message_contents_));
+  if (r_message_ids.is_error()) {
+    return send_closure(actor_id(this), &Td::send_error, id, r_message_ids.move_as_error());
+  }
+
+  send_closure(actor_id(this), &Td::send_result, id,
+               messages_manager_->get_messages_object(-1, dialog_id, r_message_ids.ok()));
+}
+
+void Td::on_request(uint64 id, td_api::sendBotStartMessage &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.parameter_);
+
+  DialogId dialog_id(request.chat_id_);
+  auto r_new_message_id =
+      messages_manager_->send_bot_start_message(UserId(request.bot_user_id_), dialog_id, request.parameter_);
+  if (r_new_message_id.is_error()) {
+    return send_closure(actor_id(this), &Td::send_error, id, r_new_message_id.move_as_error());
+  }
+
+  CHECK(r_new_message_id.ok().is_valid());
+  send_closure(actor_id(this), &Td::send_result, id,
+               messages_manager_->get_message_object({dialog_id, r_new_message_id.ok()}));
+}
+
+void Td::on_request(uint64 id, td_api::sendInlineQueryResultMessage &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.result_id_);
+
+  DialogId dialog_id(request.chat_id_);
+  auto r_new_message_id = messages_manager_->send_inline_query_result_message(
+      dialog_id, MessageId(request.reply_to_message_id_), request.disable_notification_, request.from_background_,
+      request.query_id_, request.result_id_);
+  if (r_new_message_id.is_error()) {
+    return send_closure(actor_id(this), &Td::send_error, id, r_new_message_id.move_as_error());
+  }
+
+  CHECK(r_new_message_id.ok().is_valid());
+  send_closure(actor_id(this), &Td::send_result, id,
+               messages_manager_->get_message_object({dialog_id, r_new_message_id.ok()}));
+}
+
+void Td::on_request(uint64 id, const td_api::sendChatSetTtlMessage &request) {
+  CHECK_AUTH();
+
+  DialogId dialog_id(request.chat_id_);
+  auto r_new_message_id = messages_manager_->send_dialog_set_ttl_message(dialog_id, request.ttl_);
+  if (r_new_message_id.is_error()) {
+    return send_closure(actor_id(this), &Td::send_error, id, r_new_message_id.move_as_error());
+  }
+
+  CHECK(r_new_message_id.ok().is_valid());
+  send_closure(actor_id(this), &Td::send_result, id,
+               messages_manager_->get_message_object({dialog_id, r_new_message_id.ok()}));
+}
+
+void Td::on_request(uint64 id, td_api::editMessageText &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(EditMessageTextRequest, request.chat_id_, request.message_id_, std::move(request.reply_markup_),
+                 std::move(request.input_message_content_));
+}
+
+void Td::on_request(uint64 id, td_api::editMessageLiveLocation &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(EditMessageLiveLocationRequest, request.chat_id_, request.message_id_,
+                 std::move(request.reply_markup_), std::move(request.location_));
+}
+
+void Td::on_request(uint64 id, td_api::editMessageCaption &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(EditMessageCaptionRequest, request.chat_id_, request.message_id_, std::move(request.reply_markup_),
+                 std::move(request.caption_));
+}
+
+void Td::on_request(uint64 id, td_api::editMessageReplyMarkup &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CREATE_REQUEST(EditMessageReplyMarkupRequest, request.chat_id_, request.message_id_,
+                 std::move(request.reply_markup_));
+}
+
+void Td::on_request(uint64 id, td_api::editInlineMessageText &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CLEAN_INPUT_STRING(request.inline_message_id_);
+  CREATE_REQUEST(EditInlineMessageTextRequest, std::move(request.inline_message_id_), std::move(request.reply_markup_),
+                 std::move(request.input_message_content_));
+}
+
+void Td::on_request(uint64 id, td_api::editInlineMessageLiveLocation &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CLEAN_INPUT_STRING(request.inline_message_id_);
+  CREATE_REQUEST(EditInlineMessageLiveLocationRequest, std::move(request.inline_message_id_),
+                 std::move(request.reply_markup_), std::move(request.location_));
+}
+
+void Td::on_request(uint64 id, td_api::editInlineMessageCaption &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CLEAN_INPUT_STRING(request.inline_message_id_);
+  CREATE_REQUEST(EditInlineMessageCaptionRequest, std::move(request.inline_message_id_),
+                 std::move(request.reply_markup_), std::move(request.caption_));
+}
+
+void Td::on_request(uint64 id, td_api::editInlineMessageReplyMarkup &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CLEAN_INPUT_STRING(request.inline_message_id_);
+  CREATE_REQUEST(EditInlineMessageReplyMarkupRequest, std::move(request.inline_message_id_),
+                 std::move(request.reply_markup_));
+}
+
+void Td::on_request(uint64 id, td_api::setGameScore &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CREATE_REQUEST(SetGameScoreRequest, request.chat_id_, request.message_id_, request.edit_message_, request.user_id_,
+                 request.score_, request.force_);
+}
+
+void Td::on_request(uint64 id, td_api::setInlineGameScore &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CLEAN_INPUT_STRING(request.inline_message_id_);
+  CREATE_REQUEST(SetInlineGameScoreRequest, std::move(request.inline_message_id_), request.edit_message_,
+                 request.user_id_, request.score_, request.force_);
+}
+
+void Td::on_request(uint64 id, td_api::getGameHighScores &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CREATE_REQUEST(GetGameHighScoresRequest, request.chat_id_, request.message_id_, request.user_id_);
+}
+
+void Td::on_request(uint64 id, td_api::getInlineGameHighScores &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CLEAN_INPUT_STRING(request.inline_message_id_);
+  CREATE_REQUEST(GetInlineGameHighScoresRequest, std::move(request.inline_message_id_), request.user_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::deleteChatReplyMarkup &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  answer_ok_query(
+      id, messages_manager_->delete_dialog_reply_markup(DialogId(request.chat_id_), MessageId(request.message_id_)));
+}
+
+void Td::on_request(uint64 id, td_api::sendChatAction &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(SendChatActionRequest, request.chat_id_, std::move(request.action_));
+}
+
+void Td::on_request(uint64 id, td_api::sendChatScreenshotTakenNotification &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  answer_ok_query(id, messages_manager_->send_screenshot_taken_notification_message(DialogId(request.chat_id_)));
+}
+
+void Td::on_request(uint64 id, const td_api::forwardMessages &request) {
+  CHECK_AUTH();
+
+  DialogId dialog_id(request.chat_id_);
+  auto r_message_ids = messages_manager_->forward_messages(
+      dialog_id, DialogId(request.from_chat_id_), MessagesManager::get_message_ids(request.message_ids_),
+      request.disable_notification_, request.from_background_, false, request.as_album_);
+  if (r_message_ids.is_error()) {
+    return send_closure(actor_id(this), &Td::send_error, id, r_message_ids.move_as_error());
+  }
+
+  send_closure(actor_id(this), &Td::send_result, id,
+               messages_manager_->get_messages_object(-1, dialog_id, r_message_ids.ok()));
+}
+
+void Td::on_request(uint64 id, td_api::getWebPagePreview &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(GetWebPagePreviewRequest, std::move(request.text_));
+}
+
+void Td::on_request(uint64 id, td_api::getWebPageInstantView &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.url_);
+  CREATE_REQUEST(GetWebPageInstantViewRequest, std::move(request.url_), request.force_full_);
+}
+
+void Td::on_request(uint64 id, const td_api::createPrivateChat &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(CreateChatRequest, DialogId(UserId(request.user_id_)), request.force_);
+}
+
+void Td::on_request(uint64 id, const td_api::createBasicGroupChat &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(CreateChatRequest, DialogId(ChatId(request.basic_group_id_)), request.force_);
+}
+
+void Td::on_request(uint64 id, const td_api::createSupergroupChat &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(CreateChatRequest, DialogId(ChannelId(request.supergroup_id_)), request.force_);
+}
+
+void Td::on_request(uint64 id, td_api::createSecretChat &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(CreateChatRequest, DialogId(SecretChatId(request.secret_chat_id_)), true);
+}
+
+void Td::on_request(uint64 id, td_api::createNewBasicGroupChat &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.title_);
+  CREATE_REQUEST(CreateNewGroupChatRequest, request.user_ids_, std::move(request.title_));
+}
+
+void Td::on_request(uint64 id, td_api::createNewSupergroupChat &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.title_);
+  CLEAN_INPUT_STRING(request.description_);
+  CREATE_REQUEST(CreateNewSupergroupChatRequest, std::move(request.title_), !request.is_channel_,
+                 std::move(request.description_));
+}
+void Td::on_request(uint64 id, td_api::createNewSecretChat &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(CreateNewSecretChatRequest, request.user_id_);
+}
+
+void Td::on_request(uint64 id, td_api::createCall &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<CallId> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(result.ok().as_td_api());
+    }
+  });
+
+  if (!request.protocol_) {
+    return query_promise.set_error(Status::Error(5, "CallProtocol must not be empty"));
+  }
+
+  UserId user_id(request.user_id_);
+  auto input_user = contacts_manager_->get_input_user(user_id);
+  if (input_user == nullptr) {
+    return query_promise.set_error(Status::Error(6, "User not found"));
+  }
+
+  if (!G()->shared_config().get_option_boolean("calls_enabled")) {
+    return query_promise.set_error(Status::Error(7, "Calls are not enabled for the current user"));
+  }
+
+  send_closure(G()->call_manager(), &CallManager::create_call, user_id, std::move(input_user),
+               CallProtocol::from_td_api(*request.protocol_), std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, td_api::discardCall &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(make_tl_object<td_api::ok>());
+    }
+  });
+  send_closure(G()->call_manager(), &CallManager::discard_call, CallId(request.call_id_), request.is_disconnected_,
+               request.duration_, request.connection_id_, std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, td_api::acceptCall &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(make_tl_object<td_api::ok>());
+    }
+  });
+  if (!request.protocol_) {
+    return query_promise.set_error(Status::Error(5, "Call protocol must not be empty"));
+  }
+  send_closure(G()->call_manager(), &CallManager::accept_call, CallId(request.call_id_),
+               CallProtocol::from_td_api(*request.protocol_), std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, td_api::sendCallRating &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.comment_);
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(make_tl_object<td_api::ok>());
+    }
+  });
+  send_closure(G()->call_manager(), &CallManager::rate_call, CallId(request.call_id_), request.rating_,
+               std::move(request.comment_), std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, td_api::sendCallDebugInformation &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.debug_information_);
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(make_tl_object<td_api::ok>());
+    }
+  });
+  send_closure(G()->call_manager(), &CallManager::send_call_debug_information, CallId(request.call_id_),
+               std::move(request.debug_information_), std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, const td_api::upgradeBasicGroupChatToSupergroupChat &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(UpgradeGroupChatToSupergroupChatRequest, request.chat_id_);
+}
+
+void Td::on_request(uint64 id, td_api::setChatTitle &request) {
+  CHECK_AUTH();
+  CLEAN_INPUT_STRING(request.title_);
+  CREATE_REQUEST(SetChatTitleRequest, request.chat_id_, std::move(request.title_));
+}
+
+void Td::on_request(uint64 id, td_api::setChatPhoto &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(SetChatPhotoRequest, request.chat_id_, std::move(request.photo_));
+}
+
+void Td::on_request(uint64 id, td_api::setChatDraftMessage &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  answer_ok_query(
+      id, messages_manager_->set_dialog_draft_message(DialogId(request.chat_id_), std::move(request.draft_message_)));
+}
+
+void Td::on_request(uint64 id, const td_api::toggleChatIsPinned &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  answer_ok_query(id, messages_manager_->toggle_dialog_is_pinned(DialogId(request.chat_id_), request.is_pinned_));
+}
+
+void Td::on_request(uint64 id, const td_api::setPinnedChats &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  answer_ok_query(id, messages_manager_->set_pinned_dialogs(
+                          transform(request.chat_ids_, [](int64 chat_id) { return DialogId(chat_id); })));
+}
+
+void Td::on_request(uint64 id, td_api::setChatClientData &request) {
+  CHECK_AUTH();
+  answer_ok_query(
+      id, messages_manager_->set_dialog_client_data(DialogId(request.chat_id_), std::move(request.client_data_)));
+}
+
+void Td::on_request(uint64 id, const td_api::addChatMember &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(AddChatMemberRequest, request.chat_id_, request.user_id_, request.forward_limit_);
+}
+
+void Td::on_request(uint64 id, const td_api::addChatMembers &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(AddChatMembersRequest, request.chat_id_, request.user_ids_);
+}
+
+void Td::on_request(uint64 id, td_api::setChatMemberStatus &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(SetChatMemberStatusRequest, request.chat_id_, request.user_id_, std::move(request.status_));
+}
+
+void Td::on_request(uint64 id, const td_api::getChatMember &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetChatMemberRequest, request.chat_id_, request.user_id_);
+}
+
+void Td::on_request(uint64 id, td_api::searchChatMembers &request) {
+  CHECK_AUTH();
+  CLEAN_INPUT_STRING(request.query_);
+  CREATE_REQUEST(SearchChatMembersRequest, request.chat_id_, std::move(request.query_), request.limit_);
+}
+
+void Td::on_request(uint64 id, td_api::getChatAdministrators &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetChatAdministratorsRequest, request.chat_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::generateChatInviteLink &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GenerateChatInviteLinkRequest, request.chat_id_);
+}
+
+void Td::on_request(uint64 id, td_api::checkChatInviteLink &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.invite_link_);
+  CREATE_REQUEST(CheckChatInviteLinkRequest, request.invite_link_);
+}
+
+void Td::on_request(uint64 id, td_api::joinChatByInviteLink &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.invite_link_);
+  CREATE_REQUEST(JoinChatByInviteLinkRequest, request.invite_link_);
+}
+
+void Td::on_request(uint64 id, td_api::getChatEventLog &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.query_);
+  CREATE_REQUEST(GetChatEventLogRequest, request.chat_id_, std::move(request.query_), request.from_event_id_,
+                 request.limit_, std::move(request.filters_), std::move(request.user_ids_));
+}
+
+void Td::on_request(uint64 id, const td_api::downloadFile &request) {
+  CHECK_AUTH();
+
+  auto priority = request.priority_;
+  if (!(1 <= priority && priority <= 32)) {
+    return send_error_raw(id, 5, "Download priority must be in [1;32] range");
+  }
+  file_manager_->download(FileId(request.file_id_, 0), download_file_callback_, priority);
+
+  auto file = file_manager_->get_file_object(FileId(request.file_id_, 0), false);
+  if (file->id_ == 0) {
+    return send_error_raw(id, 400, "Invalid file id");
+  }
+
+  send_closure(actor_id(this), &Td::send_result, id, std::move(file));
+}
+
+void Td::on_request(uint64 id, const td_api::cancelDownloadFile &request) {
+  CHECK_AUTH();
+
+  file_manager_->download(FileId(request.file_id_, 0), nullptr, request.only_if_pending_ ? -1 : 0);
+
+  send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::ok>());
+}
+
+void Td::on_request(uint64 id, td_api::uploadFile &request) {
+  CHECK_AUTH();
+
+  auto priority = request.priority_;
+  if (!(1 <= priority && priority <= 32)) {
+    return send_error_raw(id, 5, "Upload priority must be in [1;32] range");
+  }
+
+  auto file_type = request.file_type_ == nullptr ? FileType::Temp : from_td_api(*request.file_type_);
+  bool is_secret = file_type == FileType::Encrypted || file_type == FileType::EncryptedThumbnail;
+  auto r_file_id = file_manager_->get_input_file_id(file_type, request.file_, DialogId(), false, is_secret, true);
+  if (r_file_id.is_error()) {
+    return send_error_raw(id, 400, r_file_id.error().message());
+  }
+  auto file_id = r_file_id.ok();
+  auto upload_file_id = file_manager_->dup_file_id(file_id);
+
+  file_manager_->upload(upload_file_id, upload_file_callback_, priority, 0);
+
+  send_closure(actor_id(this), &Td::send_result, id, file_manager_->get_file_object(upload_file_id, false));
+}
+
+void Td::on_request(uint64 id, const td_api::cancelUploadFile &request) {
+  CHECK_AUTH();
+
+  file_manager_->upload(FileId(request.file_id_, 0), nullptr, 0, 0);
+
+  send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::ok>());
+}
+
+void Td::on_request(uint64 id, const td_api::setFileGenerationProgress &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(make_tl_object<td_api::ok>());
+    }
+  });
+  send_closure(file_manager_actor_, &FileManager::external_file_generate_progress, request.generation_id_,
+               request.expected_size_, request.local_prefix_size_, std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, td_api::finishFileGeneration &request) {
+  CHECK_AUTH();
+  Status status;
+  if (request.error_ != nullptr) {
+    CLEAN_INPUT_STRING(request.error_->message_);
+    status = Status::Error(request.error_->code_, request.error_->message_);
+  }
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(make_tl_object<td_api::ok>());
+    }
+  });
+  send_closure(file_manager_actor_, &FileManager::external_file_generate_finish, request.generation_id_,
+               std::move(status), std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, const td_api::deleteFile &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(make_tl_object<td_api::ok>());
+    }
+  });
+
+  send_closure(file_manager_actor_, &FileManager::delete_file, FileId(request.file_id_, 0), std::move(query_promise),
+               "td_api::deleteFile");
+}
+
+void Td::on_request(uint64 id, const td_api::blockUser &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  answer_ok_query(id, contacts_manager_->block_user(UserId(request.user_id_)));
+}
+
+void Td::on_request(uint64 id, const td_api::unblockUser &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  answer_ok_query(id, contacts_manager_->unblock_user(UserId(request.user_id_)));
+}
+
+void Td::on_request(uint64 id, const td_api::getBlockedUsers &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(GetBlockedUsersRequest, request.offset_, request.limit_);
+}
+
+void Td::on_request(uint64 id, td_api::importContacts &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  for (auto &contact : request.contacts_) {
+    if (contact == nullptr) {
+      return send_error_raw(id, 5, "Contact must not be empty");
+    }
+    CLEAN_INPUT_STRING(contact->phone_number_);
+    CLEAN_INPUT_STRING(contact->first_name_);
+    CLEAN_INPUT_STRING(contact->last_name_);
+  }
+  CREATE_REQUEST(ImportContactsRequest, std::move(request.contacts_));
+}
+
+void Td::on_request(uint64 id, td_api::searchContacts &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.query_);
+  CREATE_REQUEST(SearchContactsRequest, request.query_, request.limit_);
+}
+
+void Td::on_request(uint64 id, td_api::removeContacts &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(RemoveContactsRequest, std::move(request.user_ids_));
+}
+
+void Td::on_request(uint64 id, const td_api::getImportedContactCount &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(GetImportedContactCountRequest);
+}
+
+void Td::on_request(uint64 id, td_api::changeImportedContacts &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  for (auto &contact : request.contacts_) {
+    if (contact == nullptr) {
+      return send_error_raw(id, 5, "Contact must not be empty");
+    }
+    CLEAN_INPUT_STRING(contact->phone_number_);
+    CLEAN_INPUT_STRING(contact->first_name_);
+    CLEAN_INPUT_STRING(contact->last_name_);
+  }
+  CREATE_REQUEST(ChangeImportedContactsRequest, std::move(request.contacts_));
+}
+
+void Td::on_request(uint64 id, const td_api::clearImportedContacts &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(ClearImportedContactsRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::getRecentInlineBots &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(GetRecentInlineBotsRequest);
+}
+
+void Td::on_request(uint64 id, td_api::setName &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.first_name_);
+  CLEAN_INPUT_STRING(request.last_name_);
+  CREATE_REQUEST(SetNameRequest, std::move(request.first_name_), std::move(request.last_name_));
+}
+
+void Td::on_request(uint64 id, td_api::setBio &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.bio_);
+  CREATE_REQUEST(SetBioRequest, std::move(request.bio_));
+}
+
+void Td::on_request(uint64 id, td_api::setUsername &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.username_);
+  CREATE_REQUEST(SetUsernameRequest, std::move(request.username_));
+}
+
+void Td::on_request(uint64 id, td_api::setProfilePhoto &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(SetProfilePhotoRequest, std::move(request.photo_));
+}
+
+void Td::on_request(uint64 id, const td_api::deleteProfilePhoto &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(DeleteProfilePhotoRequest, request.profile_photo_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::getUserProfilePhotos &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetUserProfilePhotosRequest, request.user_id_, request.offset_, request.limit_);
+}
+
+void Td::on_request(uint64 id, const td_api::toggleBasicGroupAdministrators &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(ToggleGroupAdministratorsRequest, request.basic_group_id_, request.everyone_is_administrator_);
+}
+
+void Td::on_request(uint64 id, td_api::setSupergroupUsername &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.username_);
+  CREATE_REQUEST(SetSupergroupUsernameRequest, request.supergroup_id_, std::move(request.username_));
+}
+
+void Td::on_request(uint64 id, const td_api::setSupergroupStickerSet &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(SetSupergroupStickerSetRequest, request.supergroup_id_, request.sticker_set_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::toggleSupergroupInvites &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(ToggleSupergroupInvitesRequest, request.supergroup_id_, request.anyone_can_invite_);
+}
+
+void Td::on_request(uint64 id, const td_api::toggleSupergroupSignMessages &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(ToggleSupergroupSignMessagesRequest, request.supergroup_id_, request.sign_messages_);
+}
+
+void Td::on_request(uint64 id, const td_api::toggleSupergroupIsAllHistoryAvailable &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(ToggleSupergroupIsAllHistoryAvailableRequest, request.supergroup_id_,
+                 request.is_all_history_available_);
+}
+
+void Td::on_request(uint64 id, td_api::setSupergroupDescription &request) {
+  CHECK_AUTH();
+  CLEAN_INPUT_STRING(request.description_);
+  CREATE_REQUEST(SetSupergroupDescriptionRequest, request.supergroup_id_, std::move(request.description_));
+}
+
+void Td::on_request(uint64 id, const td_api::pinSupergroupMessage &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(PinSupergroupMessageRequest, request.supergroup_id_, request.message_id_,
+                 request.disable_notification_);
+}
+
+void Td::on_request(uint64 id, const td_api::unpinSupergroupMessage &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(UnpinSupergroupMessageRequest, request.supergroup_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::reportSupergroupSpam &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(ReportSupergroupSpamRequest, request.supergroup_id_, request.user_id_, request.message_ids_);
+}
+
+void Td::on_request(uint64 id, td_api::getSupergroupMembers &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetSupergroupMembersRequest, request.supergroup_id_, std::move(request.filter_), request.offset_,
+                 request.limit_);
+}
+
+void Td::on_request(uint64 id, const td_api::deleteSupergroup &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(DeleteSupergroupRequest, request.supergroup_id_);
+}
+
+void Td::on_request(uint64 id, td_api::closeSecretChat &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(make_tl_object<td_api::ok>());
+    }
+  });
+  send_closure(secret_chats_manager_, &SecretChatsManager::cancel_chat, SecretChatId(request.secret_chat_id_),
+               std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, td_api::getStickers &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.emoji_);
+  CREATE_REQUEST(GetStickersRequest, std::move(request.emoji_), request.limit_);
+}
+
+void Td::on_request(uint64 id, td_api::searchStickers &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.emoji_);
+  CREATE_REQUEST(SearchStickersRequest, std::move(request.emoji_), request.limit_);
+}
+
+void Td::on_request(uint64 id, const td_api::getInstalledStickerSets &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(GetInstalledStickerSetsRequest, request.is_masks_);
+}
+
+void Td::on_request(uint64 id, const td_api::getArchivedStickerSets &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(GetArchivedStickerSetsRequest, request.is_masks_, request.offset_sticker_set_id_, request.limit_);
+}
+
+void Td::on_request(uint64 id, const td_api::getTrendingStickerSets &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(GetTrendingStickerSetsRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::getAttachedStickerSets &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(GetAttachedStickerSetsRequest, request.file_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::getStickerSet &request) {
+  CHECK_AUTH();
+  CREATE_REQUEST(GetStickerSetRequest, request.set_id_);
+}
+
+void Td::on_request(uint64 id, td_api::searchStickerSet &request) {
+  CHECK_AUTH();
+  CLEAN_INPUT_STRING(request.name_);
+  CREATE_REQUEST(SearchStickerSetRequest, std::move(request.name_));
+}
+
+void Td::on_request(uint64 id, td_api::searchInstalledStickerSets &request) {
+  CHECK_AUTH();
+  CLEAN_INPUT_STRING(request.query_);
+  CREATE_REQUEST(SearchInstalledStickerSetsRequest, request.is_masks_, std::move(request.query_), request.limit_);
+}
+
+void Td::on_request(uint64 id, td_api::searchStickerSets &request) {
+  CHECK_AUTH();
+  CLEAN_INPUT_STRING(request.query_);
+  CREATE_REQUEST(SearchStickerSetsRequest, std::move(request.query_));
+}
+
+void Td::on_request(uint64 id, const td_api::changeStickerSet &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(ChangeStickerSetRequest, request.set_id_, request.is_installed_, request.is_archived_);
+}
+
+void Td::on_request(uint64 id, const td_api::viewTrendingStickerSets &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  stickers_manager_->view_featured_sticker_sets(request.sticker_set_ids_);
+  send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::ok>());
+}
+
+void Td::on_request(uint64 id, td_api::reorderInstalledStickerSets &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(ReorderInstalledStickerSetsRequest, request.is_masks_, std::move(request.sticker_set_ids_));
+}
+
+void Td::on_request(uint64 id, td_api::uploadStickerFile &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CREATE_REQUEST(UploadStickerFileRequest, request.user_id_, std::move(request.png_sticker_));
+}
+
+void Td::on_request(uint64 id, td_api::createNewStickerSet &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CLEAN_INPUT_STRING(request.title_);
+  CLEAN_INPUT_STRING(request.name_);
+  CREATE_REQUEST(CreateNewStickerSetRequest, request.user_id_, std::move(request.title_), std::move(request.name_),
+                 request.is_masks_, std::move(request.stickers_));
+}
+
+void Td::on_request(uint64 id, td_api::addStickerToSet &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CLEAN_INPUT_STRING(request.name_);
+  CREATE_REQUEST(AddStickerToSetRequest, request.user_id_, std::move(request.name_), std::move(request.sticker_));
+}
+
+void Td::on_request(uint64 id, td_api::setStickerPositionInSet &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CREATE_REQUEST(SetStickerPositionInSetRequest, std::move(request.sticker_), request.position_);
+}
+
+void Td::on_request(uint64 id, td_api::removeStickerFromSet &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CREATE_REQUEST(RemoveStickerFromSetRequest, std::move(request.sticker_));
+}
+
+void Td::on_request(uint64 id, const td_api::getRecentStickers &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(GetRecentStickersRequest, request.is_attached_);
+}
+
+void Td::on_request(uint64 id, td_api::addRecentSticker &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(AddRecentStickerRequest, request.is_attached_, std::move(request.sticker_));
+}
+
+void Td::on_request(uint64 id, td_api::removeRecentSticker &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(RemoveRecentStickerRequest, request.is_attached_, std::move(request.sticker_));
+}
+
+void Td::on_request(uint64 id, td_api::clearRecentStickers &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(ClearRecentStickersRequest, request.is_attached_);
+}
+
+void Td::on_request(uint64 id, const td_api::getFavoriteStickers &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(GetFavoriteStickersRequest);
+}
+
+void Td::on_request(uint64 id, td_api::addFavoriteSticker &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(AddFavoriteStickerRequest, std::move(request.sticker_));
+}
+
+void Td::on_request(uint64 id, td_api::removeFavoriteSticker &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(RemoveFavoriteStickerRequest, std::move(request.sticker_));
+}
+
+void Td::on_request(uint64 id, td_api::getStickerEmojis &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(GetStickerEmojisRequest, std::move(request.sticker_));
+}
+
+void Td::on_request(uint64 id, const td_api::getSavedAnimations &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(GetSavedAnimationsRequest);
+}
+
+void Td::on_request(uint64 id, td_api::addSavedAnimation &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(AddSavedAnimationRequest, std::move(request.animation_));
+}
+
+void Td::on_request(uint64 id, td_api::removeSavedAnimation &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(RemoveSavedAnimationRequest, std::move(request.animation_));
+}
+
+void Td::on_request(uint64 id, const td_api::getNotificationSettings &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(GetNotificationSettingsRequest, messages_manager_->get_notification_settings_scope(request.scope_));
+}
+
+void Td::on_request(uint64 id, const td_api::getChatReportSpamState &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(GetChatReportSpamStateRequest, request.chat_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::changeChatReportSpamState &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(ChangeChatReportSpamStateRequest, request.chat_id_, request.is_spam_chat_);
+}
+
+void Td::on_request(uint64 id, td_api::reportChat &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(ReportChatRequest, request.chat_id_, std::move(request.reason_), request.message_ids_);
+}
+
+void Td::on_request(uint64 id, td_api::setNotificationSettings &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.notification_settings_->sound_);
+  answer_ok_query(id, messages_manager_->set_notification_settings(
+                          messages_manager_->get_notification_settings_scope(request.scope_),
+                          std::move(request.notification_settings_)));
+}
+
+void Td::on_request(uint64 id, const td_api::resetAllNotificationSettings &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  messages_manager_->reset_all_notification_settings();
+  send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::ok>());
+}
+
+void Td::on_request(uint64 id, td_api::getOption &request) {
+  CLEAN_INPUT_STRING(request.name_);
+
+  tl_object_ptr<td_api::OptionValue> option_value;
+  switch (request.name_[0]) {
+    case 'o':
+      if (request.name_ == "online") {
+        option_value = make_tl_object<td_api::optionValueBoolean>(is_online_);
+      }
+      break;
+    case 'v':
+      if (request.name_ == "version") {
+        option_value = make_tl_object<td_api::optionValueString>(TDLIB_VERSION);
+      }
+      break;
+  }
+  if (option_value == nullptr) {
+    option_value = G()->shared_config().get_option_value(request.name_);
+  }
+  send_closure(actor_id(this), &Td::send_result, id, std::move(option_value));
+}
+
+void Td::on_request(uint64 id, td_api::setOption &request) {
+  CLEAN_INPUT_STRING(request.name_);
+  int32 value_constructor_id = request.value_ == nullptr ? td_api::optionValueEmpty::ID : request.value_->get_id();
+
+  auto set_integer_option = [&](Slice name, int32 min = 0, int32 max = std::numeric_limits<int32>::max()) {
+    if (request.name_ == name) {
+      if (value_constructor_id != td_api::optionValueInteger::ID &&
+          value_constructor_id != td_api::optionValueEmpty::ID) {
+        send_error_raw(id, 3, PSLICE() << "Option \"" << name << "\" must have integer value");
+        return true;
+      }
+      if (value_constructor_id == td_api::optionValueEmpty::ID) {
+        G()->shared_config().set_option_empty(name);
+      } else {
+        int32 value = static_cast<td_api::optionValueInteger *>(request.value_.get())->value_;
+        if (value < min || value > max) {
+          send_error_raw(id, 3,
+                         PSLICE() << "Option's \"" << name << "\" value " << value << " is outside of a valid range ["
+                                  << min << ", " << max << "]");
+          return true;
+        }
+        G()->shared_config().set_option_integer(name, clamp(value, min, max));
+      }
+      send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::ok>());
+      return true;
+    }
+    return false;
+  };
+
+  auto set_boolean_option = [&](Slice name) {
+    if (request.name_ == name) {
+      if (value_constructor_id != td_api::optionValueBoolean::ID &&
+          value_constructor_id != td_api::optionValueEmpty::ID) {
+        send_error_raw(id, 3, PSLICE() << "Option \"" << name << "\" must have boolean value");
+        return true;
+      }
+      if (value_constructor_id == td_api::optionValueEmpty::ID) {
+        G()->shared_config().set_option_empty(name);
+      } else {
+        bool value = static_cast<td_api::optionValueBoolean *>(request.value_.get())->value_;
+        G()->shared_config().set_option_boolean(name, value);
+      }
+      send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::ok>());
+      return true;
+    }
+    return false;
+  };
+
+  switch (request.name_[0]) {
+    case 'd':
+      if (set_boolean_option("disable_contact_registered_notifications")) {
+        return;
+      }
+      break;
+    case 'o':
+      if (request.name_ == "online") {
+        if (value_constructor_id != td_api::optionValueBoolean::ID &&
+            value_constructor_id != td_api::optionValueEmpty::ID) {
+          return send_error_raw(id, 3, "Option \"online\" must have boolean value");
+        }
+        bool is_online = value_constructor_id == td_api::optionValueEmpty::ID ||
+                         static_cast<const td_api::optionValueBoolean *>(request.value_.get())->value_;
+        if (!auth_manager_->is_bot()) {
+          send_closure(G()->state_manager(), &StateManager::on_online, is_online);
+        }
+        if (is_online != is_online_) {
+          is_online_ = is_online;
+          on_online_updated(true, true);
+        }
+        return send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::ok>());
+      }
+      break;
+    case 's':
+      if (set_integer_option("session_count", 0, 50)) {
+        return;
+      }
+      if (set_integer_option("storage_max_files_size")) {
+        return;
+      }
+      if (set_integer_option("storage_max_time_from_last_access")) {
+        return;
+      }
+      if (set_integer_option("storage_max_file_count")) {
+        return;
+      }
+      if (set_integer_option("storage_immunity_delay")) {
+        return;
+      }
+      break;
+    case 'X':
+    case 'x': {
+      if (request.name_.size() > 255) {
+        return send_error_raw(id, 3, "Option name is too long");
+      }
+      switch (value_constructor_id) {
+        case td_api::optionValueBoolean::ID:
+          G()->shared_config().set_option_boolean(
+              request.name_, static_cast<const td_api::optionValueBoolean *>(request.value_.get())->value_);
+          break;
+        case td_api::optionValueEmpty::ID:
+          G()->shared_config().set_option_empty(request.name_);
+          break;
+        case td_api::optionValueInteger::ID:
+          G()->shared_config().set_option_integer(
+              request.name_, static_cast<const td_api::optionValueInteger *>(request.value_.get())->value_);
+          break;
+        case td_api::optionValueString::ID:
+          G()->shared_config().set_option_string(
+              request.name_, static_cast<const td_api::optionValueString *>(request.value_.get())->value_);
+          break;
+        default:
+          UNREACHABLE();
+      }
+      return send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::ok>());
+    }
+    case 'u':
+      if (set_boolean_option("use_pfs")) {
+        return;
+      }
+      if (set_boolean_option("use_quick_ack")) {
+        return;
+      }
+      if (set_boolean_option("use_storage_optimizer")) {
+        return;
+      }
+      break;
+  }
+
+  return send_error_raw(id, 3, "Option can't be set");
+}
+
+void Td::on_request(uint64 id, td_api::getInlineQueryResults &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.query_);
+  CLEAN_INPUT_STRING(request.offset_);
+  CREATE_REQUEST(GetInlineQueryResultsRequest, request.bot_user_id_, request.chat_id_, request.user_location_,
+                 std::move(request.query_), std::move(request.offset_));
+}
+
+void Td::on_request(uint64 id, td_api::answerInlineQuery &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CLEAN_INPUT_STRING(request.next_offset_);
+  CLEAN_INPUT_STRING(request.switch_pm_text_);
+  CLEAN_INPUT_STRING(request.switch_pm_parameter_);
+  CREATE_REQUEST(AnswerInlineQueryRequest, request.inline_query_id_, request.is_personal_, std::move(request.results_),
+                 request.cache_time_, std::move(request.next_offset_), std::move(request.switch_pm_text_),
+                 std::move(request.switch_pm_parameter_));
+}
+
+void Td::on_request(uint64 id, td_api::getCallbackQueryAnswer &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(GetCallbackQueryAnswerRequest, request.chat_id_, request.message_id_, std::move(request.payload_));
+}
+
+void Td::on_request(uint64 id, td_api::answerCallbackQuery &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CLEAN_INPUT_STRING(request.text_);
+  CLEAN_INPUT_STRING(request.url_);
+  CREATE_REQUEST(AnswerCallbackQueryRequest, request.callback_query_id_, std::move(request.text_), request.show_alert_,
+                 std::move(request.url_), request.cache_time_);
+}
+
+void Td::on_request(uint64 id, td_api::answerShippingQuery &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CLEAN_INPUT_STRING(request.error_message_);
+  CREATE_REQUEST(AnswerShippingQueryRequest, request.shipping_query_id_, std::move(request.shipping_options_),
+                 std::move(request.error_message_));
+}
+
+void Td::on_request(uint64 id, td_api::answerPreCheckoutQuery &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CLEAN_INPUT_STRING(request.error_message_);
+  CREATE_REQUEST(AnswerPreCheckoutQueryRequest, request.pre_checkout_query_id_, std::move(request.error_message_));
+}
+
+void Td::on_request(uint64 id, const td_api::getPaymentForm &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(GetPaymentFormRequest, request.chat_id_, request.message_id_);
+}
+
+void Td::on_request(uint64 id, td_api::validateOrderInfo &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(ValidateOrderInfoRequest, request.chat_id_, request.message_id_, std::move(request.order_info_),
+                 request.allow_save_);
+}
+
+void Td::on_request(uint64 id, td_api::sendPaymentForm &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.order_info_id_);
+  CLEAN_INPUT_STRING(request.shipping_option_id_);
+  if (request.credentials_ == nullptr) {
+    return send_error_raw(id, 400, "Input payments credentials must not be empty");
+  }
+  CREATE_REQUEST(SendPaymentFormRequest, request.chat_id_, request.message_id_, std::move(request.order_info_id_),
+                 std::move(request.shipping_option_id_), std::move(request.credentials_));
+}
+
+void Td::on_request(uint64 id, const td_api::getPaymentReceipt &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_REQUEST(GetPaymentReceiptRequest, request.chat_id_, request.message_id_);
+}
+
+void Td::on_request(uint64 id, const td_api::getSavedOrderInfo &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(GetSavedOrderInfoRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::deleteSavedOrderInfo &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(DeleteSavedOrderInfoRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::deleteSavedCredentials &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(DeleteSavedCredentialsRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::getSupportUser &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(GetSupportUserRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::getWallpapers &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(GetWallpapersRequest);
+}
+
+void Td::on_request(uint64 id, td_api::getRecentlyVisitedTMeUrls &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.referrer_);
+  CREATE_REQUEST(GetRecentlyVisitedTMeUrlsRequest, std::move(request.referrer_));
+}
+
+void Td::on_request(uint64 id, td_api::setBotUpdatesStatus &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CLEAN_INPUT_STRING(request.error_message_);
+  create_handler<SetBotUpdatesStatusQuery>()->send(request.pending_update_count_, request.error_message_);
+  send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::ok>());
+}
+
+void Td::on_request(uint64 id, td_api::sendCustomRequest &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CLEAN_INPUT_STRING(request.method_);
+  CLEAN_INPUT_STRING(request.parameters_);
+  CREATE_REQUEST(SendCustomRequestRequest, std::move(request.method_), std::move(request.parameters_));
+}
+
+void Td::on_request(uint64 id, td_api::answerCustomQuery &request) {
+  CHECK_AUTH();
+  CHECK_IS_BOT();
+  CLEAN_INPUT_STRING(request.data_);
+  CREATE_REQUEST(AnswerCustomQueryRequest, request.custom_query_id_, std::move(request.data_));
+}
+
+void Td::on_request(uint64 id, const td_api::setAlarm &request) {
+  if (request.seconds_ < 0 || request.seconds_ > 3e9) {
+    return send_error_raw(id, 400, "Wrong parameter seconds specified");
+  }
+
+  int64 alarm_id = alarm_id_++;
+  pending_alarms_.emplace(alarm_id, id);
+  alarm_timeout_.set_timeout_in(alarm_id, request.seconds_);
+}
+
+void Td::on_request(uint64 id, td_api::searchHashtags &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.prefix_);
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise =
+      PromiseCreator::lambda([promise = std::move(promise)](Result<std::vector<string>> result) mutable {
+        if (result.is_error()) {
+          promise.set_error(result.move_as_error());
+        } else {
+          promise.set_value(make_tl_object<td_api::hashtags>(result.move_as_ok()));
+        }
+      });
+  send_closure(hashtag_hints_, &HashtagHints::query, std::move(request.prefix_), request.limit_,
+               std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, td_api::removeRecentHashtag &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CLEAN_INPUT_STRING(request.hashtag_);
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(make_tl_object<td_api::ok>());
+    }
+  });
+  send_closure(hashtag_hints_, &HashtagHints::remove_hashtag, std::move(request.hashtag_), std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, const td_api::getCountryCode &request) {
+  CREATE_NO_ARGS_REQUEST(GetCountryCodeRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::getInviteText &request) {
+  CHECK_AUTH();
+  CHECK_IS_USER();
+  CREATE_NO_ARGS_REQUEST(GetInviteTextRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::getTermsOfService &request) {
+  CREATE_NO_ARGS_REQUEST(GetTermsOfServiceRequest);
+}
+
+void Td::on_request(uint64 id, const td_api::getProxy &request) {
+  CREATE_REQUEST_PROMISE(promise);
+  auto query_promise = PromiseCreator::lambda([promise = std::move(promise)](Result<Proxy> result) mutable {
+    if (result.is_error()) {
+      promise.set_error(result.move_as_error());
+    } else {
+      promise.set_value(result.move_as_ok().as_td_api());
+    }
+  });
+  send_closure(G()->connection_creator(), &ConnectionCreator::get_proxy, std::move(query_promise));
+}
+
+void Td::on_request(uint64 id, const td_api::setProxy &request) {
+  CREATE_REQUEST_PROMISE(promise);
+  send_closure(G()->connection_creator(), &ConnectionCreator::set_proxy, Proxy::from_td_api(request.proxy_));
+  promise.set_value(make_tl_object<td_api::ok>());
+}
+
+void Td::on_request(uint64 id, const td_api::getTextEntities &request) {
+  // don't check authorization state
+  send_closure(actor_id(this), &Td::send_result, id, do_static_request(request));
+}
+
+void Td::on_request(uint64 id, td_api::parseTextEntities &request) {
+  // don't check authorization state
+  send_closure(actor_id(this), &Td::send_result, id, do_static_request(request));
+}
+
+void Td::on_request(uint64 id, const td_api::getFileMimeType &request) {
+  // don't check authorization state
+  send_closure(actor_id(this), &Td::send_result, id, do_static_request(request));
+}
+
+void Td::on_request(uint64 id, const td_api::getFileExtension &request) {
+  // don't check authorization state
+  send_closure(actor_id(this), &Td::send_result, id, do_static_request(request));
+}
+
+template <class T>
+td_api::object_ptr<td_api::Object> Td::do_static_request(const T &request) {
+  return make_error(400, "Function can't be executed synchronously");
+}
+
+td_api::object_ptr<td_api::Object> Td::do_static_request(const td_api::getTextEntities &request) {
+  if (!check_utf8(request.text_)) {
+    return make_error(400, "Text must be encoded in UTF-8");
+  }
+  auto text_entities = find_entities(request.text_, false);
+  return make_tl_object<td_api::textEntities>(get_text_entities_object(text_entities));
+}
+
+td_api::object_ptr<td_api::Object> Td::do_static_request(td_api::parseTextEntities &request) {
+  if (!check_utf8(request.text_)) {
+    return make_error(400, "Text must be encoded in UTF-8");
+  }
+  if (request.parse_mode_ == nullptr) {
+    return make_error(400, "Parse mode must be non-empty");
+  }
+
+  Result<vector<MessageEntity>> r_entities;
+  switch (request.parse_mode_->get_id()) {
+    case td_api::textParseModeHTML::ID:
+      r_entities = parse_html(request.text_);
+      break;
+    case td_api::textParseModeMarkdown::ID:
+      r_entities = parse_markdown(request.text_);
+      break;
+    default:
+      UNREACHABLE();
+      break;
+  }
+  if (r_entities.is_error()) {
+    return make_error(400, PSLICE() << "Can't parse entities: " << r_entities.error().message());
+  }
+
+  return make_tl_object<td_api::formattedText>(std::move(request.text_), get_text_entities_object(r_entities.ok()));
+}
+
+td_api::object_ptr<td_api::Object> Td::do_static_request(const td_api::getFileMimeType &request) {
+  // don't check file name UTF-8 correctness
+  return make_tl_object<td_api::text>(MimeType::from_extension(PathView(request.file_name_).extension()));
+}
+
+td_api::object_ptr<td_api::Object> Td::do_static_request(const td_api::getFileExtension &request) {
+  // don't check MIME type UTF-8 correctness
+  return make_tl_object<td_api::text>(MimeType::to_extension(request.mime_type_));
+}
+
+// test
+void Td::on_request(uint64 id, td_api::testNetwork &request) {
+  create_handler<TestQuery>(id)->send();
+}
+
+void Td::on_request(uint64 id, td_api::testGetDifference &request) {
+  CHECK_AUTH();
+  updates_manager_->get_difference("testGetDifference");
+  send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::ok>());
+}
+
+void Td::on_request(uint64 id, td_api::testUseUpdate &request) {
+  send_closure(actor_id(this), &Td::send_result, id, nullptr);
+}
+
+void Td::on_request(uint64 id, td_api::testUseError &request) {
+  send_closure(actor_id(this), &Td::send_result, id, nullptr);
+}
+
+void Td::on_request(uint64 id, td_api::testCallEmpty &request) {
+  send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::ok>());
+}
+
+void Td::on_request(uint64 id, td_api::testSquareInt &request) {
+  send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::testInt>(request.x_ * request.x_));
+}
+
+void Td::on_request(uint64 id, td_api::testCallString &request) {
+  send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::testString>(std::move(request.x_)));
+}
+
+void Td::on_request(uint64 id, td_api::testCallBytes &request) {
+  send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::testBytes>(std::move(request.x_)));
+}
+
+void Td::on_request(uint64 id, td_api::testCallVectorInt &request) {
+  send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::testVectorInt>(std::move(request.x_)));
+}
+
+void Td::on_request(uint64 id, td_api::testCallVectorIntObject &request) {
+  send_closure(actor_id(this), &Td::send_result, id,
+               make_tl_object<td_api::testVectorIntObject>(std::move(request.x_)));
+}
+
+void Td::on_request(uint64 id, td_api::testCallVectorString &request) {
+  send_closure(actor_id(this), &Td::send_result, id, make_tl_object<td_api::testVectorString>(std::move(request.x_)));
+}
+
+void Td::on_request(uint64 id, td_api::testCallVectorStringObject &request) {
+  send_closure(actor_id(this), &Td::send_result, id,
+               make_tl_object<td_api::testVectorStringObject>(std::move(request.x_)));
+}
+
+#undef CLEAN_INPUT_STRING
+#undef CHECK_AUTH
+#undef CHECK_IS_BOT
+#undef CHECK_IS_USER
+#undef CREATE_NO_ARGS_REQUEST
+#undef CREATE_REQUEST
+#undef CREATE_REQUEST_PROMISE
+
+constexpr const char *Td::TDLIB_VERSION;
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Td.h b/libs/tdlib/td/td/telegram/Td.h
new file mode 100644
index 0000000000..69595ef159
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Td.h
@@ -0,0 +1,818 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/net/NetQuery.h"
+#include "td/telegram/StateManager.h"
+#include "td/telegram/TdCallback.h"
+#include "td/telegram/TdDb.h"
+#include "td/telegram/TdParameters.h"
+
+#include "td/telegram/td_api.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/Timeout.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/Container.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <memory>
+#include <unordered_map>
+#include <unordered_set>
+#include <utility>
+
+namespace td {
+class AnimationsManager;
+class AudiosManager;
+class AuthManager;
+class CallManager;
+class CallbackQueriesManager;
+class ChangePhoneNumberManager;
+class ConfigManager;
+class ContactsManager;
+class DeviceTokenManager;
+class DocumentsManager;
+class FileManager;
+class InlineQueriesManager;
+class HashtagHints;
+class MessagesManager;
+class NetStatsManager;
+class PasswordManager;
+class PrivacyManager;
+class SecretChatsManager;
+class StickersManager;
+class StorageManager;
+class TopDialogManager;
+class UpdatesManager;
+class VideoNotesManager;
+class VideosManager;
+class VoiceNotesManager;
+class WebPagesManager;
+
+template <class T>
+class Promise;
+}  // namespace td
+
+namespace td {
+
+// Td may start closing after explicit "close" or "destroy" query.
+// Or it may start closing by itself, because authorization is lost.
+// It any case the parent will be notified via updateAuthorizationState.
+//
+// Td needs a way to know that it will receive no more queries.
+// It happens after "hangup".
+//
+// Parent needs a way to know that it will receive no more updates.
+// It happens after destruction of callback or after on_closed.
+class Td final : public NetQueryCallback {
+ public:
+  Td(const Td &) = delete;
+  Td(Td &&) = delete;
+  Td &operator=(const Td &) = delete;
+  Td &operator=(Td &&) = delete;
+
+  explicit Td(unique_ptr<TdCallback> callback);
+
+  void request(uint64 id, tl_object_ptr<td_api::Function> function);
+
+  void destroy();
+  void close();
+
+  void update_qts(int32 qts);
+
+  void force_get_difference();
+
+  void on_result(NetQueryPtr query) override;
+  void on_connection_state_changed(StateManager::State new_state);
+  void on_authorization_lost();
+
+  void on_online_updated(bool force, bool send_update);
+  void on_update_status_success(bool is_online);
+
+  void on_channel_unban_timeout(int64 channel_id_long);
+
+  bool is_online() const;
+
+  template <class ActorT, class... ArgsT>
+  ActorId<ActorT> create_net_actor(ArgsT &&... args) {
+    auto slot_id = request_actors_.create(ActorOwn<>(), RequestActorIdType);
+    inc_request_actor_refcnt();
+    auto actor = make_unique<ActorT>(std::forward<ArgsT>(args)...);
+    actor->set_parent(actor_shared(this, slot_id));
+
+    auto actor_own = register_actor("net_actor", std::move(actor));
+    auto actor_id = actor_own.get();
+    *request_actors_.get(slot_id) = std::move(actor_own);
+    return actor_id;
+  }
+
+  unique_ptr<AudiosManager> audios_manager_;
+  unique_ptr<CallbackQueriesManager> callback_queries_manager_;
+  unique_ptr<DocumentsManager> documents_manager_;
+  unique_ptr<VideoNotesManager> video_notes_manager_;
+  unique_ptr<VideosManager> videos_manager_;
+  unique_ptr<VoiceNotesManager> voice_notes_manager_;
+
+  std::unique_ptr<AnimationsManager> animations_manager_;
+  ActorOwn<AnimationsManager> animations_manager_actor_;
+  std::unique_ptr<AuthManager> auth_manager_;
+  ActorOwn<AuthManager> auth_manager_actor_;
+  std::unique_ptr<ChangePhoneNumberManager> change_phone_number_manager_;
+  ActorOwn<ChangePhoneNumberManager> change_phone_number_manager_actor_;
+  std::unique_ptr<ContactsManager> contacts_manager_;
+  ActorOwn<ContactsManager> contacts_manager_actor_;
+  std::unique_ptr<FileManager> file_manager_;
+  ActorOwn<FileManager> file_manager_actor_;
+  std::unique_ptr<InlineQueriesManager> inline_queries_manager_;
+  ActorOwn<InlineQueriesManager> inline_queries_manager_actor_;
+  std::unique_ptr<MessagesManager> messages_manager_;
+  ActorOwn<MessagesManager> messages_manager_actor_;
+  std::unique_ptr<StickersManager> stickers_manager_;
+  ActorOwn<StickersManager> stickers_manager_actor_;
+  std::unique_ptr<UpdatesManager> updates_manager_;
+  ActorOwn<UpdatesManager> updates_manager_actor_;
+  std::unique_ptr<WebPagesManager> web_pages_manager_;
+  ActorOwn<WebPagesManager> web_pages_manager_actor_;
+
+  ActorOwn<CallManager> call_manager_;
+  ActorOwn<ConfigManager> config_manager_;
+  ActorOwn<DeviceTokenManager> device_token_manager_;
+  ActorOwn<HashtagHints> hashtag_hints_;
+  ActorOwn<NetStatsManager> net_stats_manager_;
+  ActorOwn<PasswordManager> password_manager_;
+  ActorOwn<PrivacyManager> privacy_manager_;
+  ActorOwn<SecretChatsManager> secret_chats_manager_;
+  ActorOwn<StateManager> state_manager_;
+  ActorOwn<StorageManager> storage_manager_;
+  ActorOwn<TopDialogManager> top_dialog_manager_;
+
+  class ResultHandler : public std::enable_shared_from_this<ResultHandler> {
+   public:
+    ResultHandler() = default;
+    ResultHandler(const ResultHandler &) = delete;
+    ResultHandler &operator=(const ResultHandler &) = delete;
+    virtual ~ResultHandler() = default;
+    virtual void on_result(NetQueryPtr query);
+    virtual void on_result(uint64 id, BufferSlice packet) {
+      UNREACHABLE();
+    }
+    virtual void on_error(uint64 id, Status status) {
+      UNREACHABLE();
+    }
+
+    friend class Td;
+
+   protected:
+    void send_query(NetQueryPtr);
+
+    Td *td = nullptr;
+
+   private:
+    void set_td(Td *new_td);
+  };
+
+  template <class HandlerT, class... Args>
+  std::shared_ptr<HandlerT> create_handler(Args &&... args) {
+    auto ptr = std::make_shared<HandlerT>(std::forward<Args>(args)...);
+    ptr->set_td(this);
+    return ptr;
+  }
+
+  void send_update(tl_object_ptr<td_api::Update> &&object);
+
+  ActorShared<Td> create_reference();
+
+  static td_api::object_ptr<td_api::Object> static_request(td_api::object_ptr<td_api::Function> function);
+
+ private:
+  static constexpr const char *TDLIB_VERSION = "1.2.0";
+  static constexpr int64 ONLINE_ALARM_ID = 0;
+  static constexpr int32 ONLINE_TIMEOUT = 240;
+  static constexpr int64 PING_SERVER_ALARM_ID = -1;
+  static constexpr int32 PING_SERVER_TIMEOUT = 300;
+
+  void send_result(uint64 id, tl_object_ptr<td_api::Object> object);
+  void send_error(uint64 id, Status error);
+  void send_error_impl(uint64 id, tl_object_ptr<td_api::error> error);
+  void send_error_raw(uint64 id, int32 code, CSlice error);
+  void answer_ok_query(uint64 id, Status status);
+
+  void inc_actor_refcnt();
+  void dec_actor_refcnt();
+
+  void inc_request_actor_refcnt();
+  void dec_request_actor_refcnt();
+
+  void on_closed();
+
+  void dec_stop_cnt();
+
+  TdParameters parameters_;
+
+  unique_ptr<TdCallback> callback_;
+
+  StateManager::State connection_state_;
+
+  std::unordered_multiset<uint64> request_set_;
+  int actor_refcnt_ = 0;
+  int request_actor_refcnt_ = 0;
+  int stop_cnt_ = 2;
+  bool destroy_flag_ = false;
+  int close_flag_ = 0;
+
+  enum class State { WaitParameters, Decrypt, Run, Close } state_ = State::WaitParameters;
+  EncryptionInfo encryption_info_;
+
+  vector<std::pair<uint64, std::shared_ptr<ResultHandler>>> result_handlers_;
+  enum : int8 { RequestActorIdType = 1, ActorIdType = 2 };
+  Container<ActorOwn<Actor>> request_actors_;
+
+  bool is_online_ = false;
+  NetQueryRef update_status_query_;
+
+  int64 alarm_id_ = 1;
+  std::unordered_map<int64, uint64> pending_alarms_;
+  MultiTimeout alarm_timeout_;
+
+  static void on_alarm_timeout_callback(void *td_ptr, int64 alarm_id);
+  void on_alarm_timeout(int64 alarm_id);
+
+  template <class T>
+  friend class RequestActor;              // uses send_result/send_error
+  friend class TestQuery;                 // uses send_result/send_error
+  friend class AuthManager;               // uses send_result/send_error
+  friend class ChangePhoneNumberManager;  // uses send_result/send_error
+
+  void add_handler(uint64 id, std::shared_ptr<ResultHandler> handler);
+  std::shared_ptr<ResultHandler> extract_handler(uint64 id);
+  void invalidate_handler(ResultHandler *handler);
+  void clear_handlers();
+  // void destroy_handler(ResultHandler *handler);
+
+  static bool is_internal_config_option(Slice name);
+
+  void on_config_option_updated(const string &name);
+
+  static tl_object_ptr<td_api::ConnectionState> get_connection_state_object(StateManager::State state);
+
+  void send(NetQueryPtr &&query);
+
+  class OnRequest;
+
+  class DownloadFileCallback;
+
+  std::shared_ptr<DownloadFileCallback> download_file_callback_;
+
+  class UploadFileCallback;
+
+  std::shared_ptr<UploadFileCallback> upload_file_callback_;
+
+  template <class T>
+  auto create_request_promise(uint64 id) {
+    return PromiseCreator::lambda([id = id, actor_id = actor_id(this)](Result<T> r_state) {
+      if (r_state.is_error()) {
+        send_closure(actor_id, &Td::send_error, id, r_state.move_as_error());
+      } else {
+        send_closure(actor_id, &Td::send_result, id, r_state.move_as_ok());
+      }
+    });
+  }
+
+  template <class T>
+  void on_request(uint64 id, const T &request) = delete;
+
+  void on_request(uint64 id, const td_api::setTdlibParameters &request);
+
+  void on_request(uint64 id, const td_api::checkDatabaseEncryptionKey &request);
+
+  void on_request(uint64 id, td_api::setDatabaseEncryptionKey &request);
+
+  void on_request(uint64 id, const td_api::getAuthorizationState &request);
+
+  void on_request(uint64 id, td_api::setAuthenticationPhoneNumber &request);
+
+  void on_request(uint64 id, const td_api::resendAuthenticationCode &request);
+
+  void on_request(uint64 id, td_api::checkAuthenticationCode &request);
+
+  void on_request(uint64 id, td_api::checkAuthenticationPassword &request);
+
+  void on_request(uint64 id, const td_api::requestAuthenticationPasswordRecovery &request);
+
+  void on_request(uint64 id, td_api::recoverAuthenticationPassword &request);
+
+  void on_request(uint64 id, const td_api::logOut &request);
+
+  void on_request(uint64 id, const td_api::close &request);
+
+  void on_request(uint64 id, const td_api::destroy &request);
+
+  void on_request(uint64 id, td_api::checkAuthenticationBotToken &request);
+
+  void on_request(uint64 id, td_api::getPasswordState &request);
+
+  void on_request(uint64 id, td_api::setPassword &request);
+
+  void on_request(uint64 id, td_api::getRecoveryEmailAddress &request);
+
+  void on_request(uint64 id, td_api::setRecoveryEmailAddress &request);
+
+  void on_request(uint64 id, td_api::requestPasswordRecovery &request);
+
+  void on_request(uint64 id, td_api::recoverPassword &request);
+
+  void on_request(uint64 id, td_api::getTemporaryPasswordState &request);
+
+  void on_request(uint64 id, td_api::createTemporaryPassword &request);
+
+  void on_request(uint64 id, td_api::processDcUpdate &request);
+
+  void on_request(uint64 id, td_api::registerDevice &request);
+
+  void on_request(uint64 id, td_api::getUserPrivacySettingRules &request);
+
+  void on_request(uint64 id, td_api::setUserPrivacySettingRules &request);
+
+  void on_request(uint64 id, const td_api::getAccountTtl &request);
+
+  void on_request(uint64 id, const td_api::setAccountTtl &request);
+
+  void on_request(uint64 id, td_api::deleteAccount &request);
+
+  void on_request(uint64 id, td_api::changePhoneNumber &request);
+
+  void on_request(uint64 id, td_api::checkChangePhoneNumberCode &request);
+
+  void on_request(uint64 id, td_api::resendChangePhoneNumberCode &request);
+
+  void on_request(uint64 id, const td_api::getActiveSessions &request);
+
+  void on_request(uint64 id, const td_api::terminateSession &request);
+
+  void on_request(uint64 id, const td_api::terminateAllOtherSessions &request);
+
+  void on_request(uint64 id, const td_api::getConnectedWebsites &request);
+
+  void on_request(uint64 id, const td_api::disconnectWebsite &request);
+
+  void on_request(uint64 id, const td_api::disconnectAllWebsites &request);
+
+  void on_request(uint64 id, const td_api::getMe &request);
+
+  void on_request(uint64 id, const td_api::getUser &request);
+
+  void on_request(uint64 id, const td_api::getUserFullInfo &request);
+
+  void on_request(uint64 id, const td_api::getBasicGroup &request);
+
+  void on_request(uint64 id, const td_api::getBasicGroupFullInfo &request);
+
+  void on_request(uint64 id, const td_api::getSupergroup &request);
+
+  void on_request(uint64 id, const td_api::getSupergroupFullInfo &request);
+
+  void on_request(uint64 id, const td_api::getSecretChat &request);
+
+  void on_request(uint64 id, const td_api::getChat &request);
+
+  void on_request(uint64 id, const td_api::getMessage &request);
+
+  void on_request(uint64 id, const td_api::getRepliedMessage &request);
+
+  void on_request(uint64 id, const td_api::getChatPinnedMessage &request);
+
+  void on_request(uint64 id, const td_api::getMessages &request);
+
+  void on_request(uint64 id, const td_api::getPublicMessageLink &request);
+
+  void on_request(uint64 id, const td_api::getFile &request);
+
+  void on_request(uint64 id, td_api::getRemoteFile &request);
+
+  void on_request(uint64 id, td_api::getStorageStatistics &request);
+
+  void on_request(uint64 id, td_api::getStorageStatisticsFast &request);
+
+  void on_request(uint64 id, td_api::optimizeStorage &request);
+
+  void on_request(uint64 id, td_api::getNetworkStatistics &request);
+
+  void on_request(uint64 id, td_api::resetNetworkStatistics &request);
+
+  void on_request(uint64 id, td_api::addNetworkStatistics &request);
+
+  void on_request(uint64 id, td_api::setNetworkType &request);
+
+  void on_request(uint64 id, td_api::getTopChats &request);
+
+  void on_request(uint64 id, const td_api::removeTopChat &request);
+
+  void on_request(uint64 id, const td_api::getChats &request);
+
+  void on_request(uint64 id, td_api::searchPublicChat &request);
+
+  void on_request(uint64 id, td_api::searchPublicChats &request);
+
+  void on_request(uint64 id, td_api::searchChats &request);
+
+  void on_request(uint64 id, td_api::searchChatsOnServer &request);
+
+  void on_request(uint64 id, const td_api::addRecentlyFoundChat &request);
+
+  void on_request(uint64 id, const td_api::removeRecentlyFoundChat &request);
+
+  void on_request(uint64 id, const td_api::clearRecentlyFoundChats &request);
+
+  void on_request(uint64 id, const td_api::getGroupsInCommon &request);
+
+  void on_request(uint64 id, td_api::checkChatUsername &request);
+
+  void on_request(uint64 id, const td_api::getCreatedPublicChats &request);
+
+  void on_request(uint64 id, const td_api::openChat &request);
+
+  void on_request(uint64 id, const td_api::closeChat &request);
+
+  void on_request(uint64 id, const td_api::viewMessages &request);
+
+  void on_request(uint64 id, const td_api::openMessageContent &request);
+
+  void on_request(uint64 id, const td_api::getChatHistory &request);
+
+  void on_request(uint64 id, const td_api::deleteChatHistory &request);
+
+  void on_request(uint64 id, td_api::searchChatMessages &request);
+
+  void on_request(uint64 id, td_api::searchSecretMessages &request);
+
+  void on_request(uint64 id, td_api::searchMessages &request);
+
+  void on_request(uint64 id, td_api::searchCallMessages &request);
+
+  void on_request(uint64 id, const td_api::searchChatRecentLocationMessages &request);
+
+  void on_request(uint64 id, const td_api::getActiveLiveLocationMessages &request);
+
+  void on_request(uint64 id, const td_api::getChatMessageByDate &request);
+
+  void on_request(uint64 id, const td_api::deleteMessages &request);
+
+  void on_request(uint64 id, const td_api::deleteChatMessagesFromUser &request);
+
+  void on_request(uint64 id, const td_api::readAllChatMentions &request);
+
+  void on_request(uint64 id, td_api::sendMessage &request);
+
+  void on_request(uint64 id, td_api::sendMessageAlbum &request);
+
+  void on_request(uint64 id, td_api::sendBotStartMessage &request);
+
+  void on_request(uint64 id, td_api::sendInlineQueryResultMessage &request);
+
+  void on_request(uint64 id, const td_api::sendChatSetTtlMessage &request);
+
+  void on_request(uint64 id, td_api::editMessageText &request);
+
+  void on_request(uint64 id, td_api::editMessageLiveLocation &request);
+
+  void on_request(uint64 id, td_api::editMessageCaption &request);
+
+  void on_request(uint64 id, td_api::editMessageReplyMarkup &request);
+
+  void on_request(uint64 id, td_api::editInlineMessageText &request);
+
+  void on_request(uint64 id, td_api::editInlineMessageLiveLocation &request);
+
+  void on_request(uint64 id, td_api::editInlineMessageCaption &request);
+
+  void on_request(uint64 id, td_api::editInlineMessageReplyMarkup &request);
+
+  void on_request(uint64 id, td_api::setGameScore &request);
+
+  void on_request(uint64 id, td_api::setInlineGameScore &request);
+
+  void on_request(uint64 id, td_api::getGameHighScores &request);
+
+  void on_request(uint64 id, td_api::getInlineGameHighScores &request);
+
+  void on_request(uint64 id, const td_api::deleteChatReplyMarkup &request);
+
+  void on_request(uint64 id, td_api::sendChatAction &request);
+
+  void on_request(uint64 id, td_api::sendChatScreenshotTakenNotification &request);
+
+  void on_request(uint64 id, const td_api::forwardMessages &request);
+
+  void on_request(uint64 id, td_api::getWebPagePreview &request);
+
+  void on_request(uint64 id, td_api::getWebPageInstantView &request);
+
+  void on_request(uint64 id, const td_api::createPrivateChat &request);
+
+  void on_request(uint64 id, const td_api::createBasicGroupChat &request);
+
+  void on_request(uint64 id, const td_api::createSupergroupChat &request);
+
+  void on_request(uint64 id, td_api::createSecretChat &request);
+
+  void on_request(uint64 id, td_api::createNewBasicGroupChat &request);
+
+  void on_request(uint64 id, td_api::createNewSupergroupChat &request);
+
+  void on_request(uint64 id, td_api::createNewSecretChat &request);
+
+  void on_request(uint64 id, td_api::createCall &request);
+
+  void on_request(uint64 id, td_api::discardCall &request);
+
+  void on_request(uint64 id, td_api::acceptCall &request);
+
+  void on_request(uint64 id, td_api::sendCallRating &request);
+
+  void on_request(uint64 id, td_api::sendCallDebugInformation &request);
+
+  void on_request(uint64 id, const td_api::upgradeBasicGroupChatToSupergroupChat &request);
+
+  void on_request(uint64 id, td_api::setChatTitle &request);
+
+  void on_request(uint64 id, td_api::setChatPhoto &request);
+
+  void on_request(uint64 id, td_api::setChatDraftMessage &request);
+
+  void on_request(uint64 id, const td_api::toggleChatIsPinned &request);
+
+  void on_request(uint64 id, const td_api::setPinnedChats &request);
+
+  void on_request(uint64 id, td_api::setChatClientData &request);
+
+  void on_request(uint64 id, const td_api::addChatMember &request);
+
+  void on_request(uint64 id, const td_api::addChatMembers &request);
+
+  void on_request(uint64 id, td_api::setChatMemberStatus &request);
+
+  void on_request(uint64 id, const td_api::getChatMember &request);
+
+  void on_request(uint64 id, td_api::searchChatMembers &request);
+
+  void on_request(uint64 id, td_api::getChatAdministrators &request);
+
+  void on_request(uint64 id, const td_api::generateChatInviteLink &request);
+
+  void on_request(uint64 id, td_api::checkChatInviteLink &request);
+
+  void on_request(uint64 id, td_api::joinChatByInviteLink &request);
+
+  void on_request(uint64 id, td_api::getChatEventLog &request);
+
+  void on_request(uint64 id, const td_api::downloadFile &request);
+
+  void on_request(uint64 id, const td_api::cancelDownloadFile &request);
+
+  void on_request(uint64 id, td_api::uploadFile &request);
+
+  void on_request(uint64 id, const td_api::cancelUploadFile &request);
+
+  void on_request(uint64 id, const td_api::setFileGenerationProgress &request);
+
+  void on_request(uint64 id, td_api::finishFileGeneration &request);
+
+  void on_request(uint64 id, const td_api::deleteFile &request);
+
+  void on_request(uint64 id, const td_api::blockUser &request);
+
+  void on_request(uint64 id, const td_api::unblockUser &request);
+
+  void on_request(uint64 id, const td_api::getBlockedUsers &request);
+
+  void on_request(uint64 id, td_api::importContacts &request);
+
+  void on_request(uint64 id, td_api::searchContacts &request);
+
+  void on_request(uint64 id, td_api::removeContacts &request);
+
+  void on_request(uint64 id, const td_api::getImportedContactCount &request);
+
+  void on_request(uint64 id, td_api::changeImportedContacts &request);
+
+  void on_request(uint64 id, const td_api::clearImportedContacts &request);
+
+  void on_request(uint64 id, const td_api::getRecentInlineBots &request);
+
+  void on_request(uint64 id, td_api::setName &request);
+
+  void on_request(uint64 id, td_api::setBio &request);
+
+  void on_request(uint64 id, td_api::setUsername &request);
+
+  void on_request(uint64 id, td_api::setProfilePhoto &request);
+
+  void on_request(uint64 id, const td_api::deleteProfilePhoto &request);
+
+  void on_request(uint64 id, const td_api::getUserProfilePhotos &request);
+
+  void on_request(uint64 id, const td_api::toggleBasicGroupAdministrators &request);
+
+  void on_request(uint64 id, td_api::setSupergroupUsername &request);
+
+  void on_request(uint64 id, const td_api::setSupergroupStickerSet &request);
+
+  void on_request(uint64 id, const td_api::toggleSupergroupInvites &request);
+
+  void on_request(uint64 id, const td_api::toggleSupergroupSignMessages &request);
+
+  void on_request(uint64 id, const td_api::toggleSupergroupIsAllHistoryAvailable &request);
+
+  void on_request(uint64 id, td_api::setSupergroupDescription &request);
+
+  void on_request(uint64 id, const td_api::pinSupergroupMessage &request);
+
+  void on_request(uint64 id, const td_api::unpinSupergroupMessage &request);
+
+  void on_request(uint64 id, const td_api::reportSupergroupSpam &request);
+
+  void on_request(uint64 id, td_api::getSupergroupMembers &request);
+
+  void on_request(uint64 id, const td_api::deleteSupergroup &request);
+
+  void on_request(uint64 id, td_api::closeSecretChat &request);
+
+  void on_request(uint64 id, td_api::getStickers &request);
+
+  void on_request(uint64 id, td_api::searchStickers &request);
+
+  void on_request(uint64 id, const td_api::getInstalledStickerSets &request);
+
+  void on_request(uint64 id, const td_api::getArchivedStickerSets &request);
+
+  void on_request(uint64 id, const td_api::getTrendingStickerSets &request);
+
+  void on_request(uint64 id, const td_api::getAttachedStickerSets &request);
+
+  void on_request(uint64 id, const td_api::getStickerSet &request);
+
+  void on_request(uint64 id, td_api::searchStickerSet &request);
+
+  void on_request(uint64 id, td_api::searchInstalledStickerSets &request);
+
+  void on_request(uint64 id, td_api::searchStickerSets &request);
+
+  void on_request(uint64 id, const td_api::changeStickerSet &request);
+
+  void on_request(uint64 id, const td_api::viewTrendingStickerSets &request);
+
+  void on_request(uint64 id, td_api::reorderInstalledStickerSets &request);
+
+  void on_request(uint64 id, td_api::uploadStickerFile &request);
+
+  void on_request(uint64 id, td_api::createNewStickerSet &request);
+
+  void on_request(uint64 id, td_api::addStickerToSet &request);
+
+  void on_request(uint64 id, td_api::setStickerPositionInSet &request);
+
+  void on_request(uint64 id, td_api::removeStickerFromSet &request);
+
+  void on_request(uint64 id, const td_api::getRecentStickers &request);
+
+  void on_request(uint64 id, td_api::addRecentSticker &request);
+
+  void on_request(uint64 id, td_api::removeRecentSticker &request);
+
+  void on_request(uint64 id, td_api::clearRecentStickers &request);
+
+  void on_request(uint64 id, const td_api::getSavedAnimations &request);
+
+  void on_request(uint64 id, td_api::addSavedAnimation &request);
+
+  void on_request(uint64 id, td_api::removeSavedAnimation &request);
+
+  void on_request(uint64 id, td_api::getStickerEmojis &request);
+
+  void on_request(uint64 id, const td_api::getFavoriteStickers &request);
+
+  void on_request(uint64 id, td_api::addFavoriteSticker &request);
+
+  void on_request(uint64 id, td_api::removeFavoriteSticker &request);
+
+  void on_request(uint64 id, const td_api::getNotificationSettings &request);
+
+  void on_request(uint64 id, td_api::setNotificationSettings &request);
+
+  void on_request(uint64 id, const td_api::resetAllNotificationSettings &request);
+
+  void on_request(uint64 id, const td_api::getChatReportSpamState &request);
+
+  void on_request(uint64 id, const td_api::changeChatReportSpamState &request);
+
+  void on_request(uint64 id, td_api::reportChat &request);
+
+  void on_request(uint64 id, td_api::getOption &request);
+
+  void on_request(uint64 id, td_api::setOption &request);
+
+  void on_request(uint64 id, td_api::getInlineQueryResults &request);
+
+  void on_request(uint64 id, td_api::answerInlineQuery &request);
+
+  void on_request(uint64 id, td_api::getCallbackQueryAnswer &request);
+
+  void on_request(uint64 id, td_api::answerCallbackQuery &request);
+
+  void on_request(uint64 id, td_api::answerShippingQuery &request);
+
+  void on_request(uint64 id, td_api::answerPreCheckoutQuery &request);
+
+  void on_request(uint64 id, const td_api::getPaymentForm &request);
+
+  void on_request(uint64 id, td_api::validateOrderInfo &request);
+
+  void on_request(uint64 id, td_api::sendPaymentForm &request);
+
+  void on_request(uint64 id, const td_api::getPaymentReceipt &request);
+
+  void on_request(uint64 id, const td_api::getSavedOrderInfo &request);
+
+  void on_request(uint64 id, const td_api::deleteSavedOrderInfo &request);
+
+  void on_request(uint64 id, const td_api::deleteSavedCredentials &request);
+
+  void on_request(uint64 id, const td_api::getSupportUser &request);
+
+  void on_request(uint64 id, const td_api::getWallpapers &request);
+
+  void on_request(uint64 id, td_api::getRecentlyVisitedTMeUrls &request);
+
+  void on_request(uint64 id, td_api::setBotUpdatesStatus &request);
+
+  void on_request(uint64 id, td_api::sendCustomRequest &request);
+
+  void on_request(uint64 id, td_api::answerCustomQuery &request);
+
+  void on_request(uint64 id, const td_api::setAlarm &request);
+
+  void on_request(uint64 id, td_api::searchHashtags &request);
+
+  void on_request(uint64 id, td_api::removeRecentHashtag &request);
+
+  void on_request(uint64 id, const td_api::getCountryCode &request);
+
+  void on_request(uint64 id, const td_api::getInviteText &request);
+
+  void on_request(uint64 id, const td_api::getTermsOfService &request);
+
+  void on_request(uint64 id, const td_api::getProxy &request);
+
+  void on_request(uint64 id, const td_api::setProxy &request);
+
+  void on_request(uint64 id, const td_api::getTextEntities &request);
+
+  void on_request(uint64 id, td_api::parseTextEntities &request);
+
+  void on_request(uint64 id, const td_api::getFileMimeType &request);
+
+  void on_request(uint64 id, const td_api::getFileExtension &request);
+
+  // test
+  void on_request(uint64 id, td_api::testNetwork &request);
+  void on_request(uint64 id, td_api::testGetDifference &request);
+  void on_request(uint64 id, td_api::testUseUpdate &request);
+  void on_request(uint64 id, td_api::testUseError &request);
+  void on_request(uint64 id, td_api::testCallEmpty &request);
+  void on_request(uint64 id, td_api::testSquareInt &request);
+  void on_request(uint64 id, td_api::testCallString &request);
+  void on_request(uint64 id, td_api::testCallBytes &request);
+  void on_request(uint64 id, td_api::testCallVectorInt &request);
+  void on_request(uint64 id, td_api::testCallVectorIntObject &request);
+  void on_request(uint64 id, td_api::testCallVectorString &request);
+  void on_request(uint64 id, td_api::testCallVectorStringObject &request);
+
+  template <class T>
+  static td_api::object_ptr<td_api::Object> do_static_request(const T &request);
+  static td_api::object_ptr<td_api::Object> do_static_request(const td_api::getTextEntities &request);
+  static td_api::object_ptr<td_api::Object> do_static_request(td_api::parseTextEntities &request);
+  static td_api::object_ptr<td_api::Object> do_static_request(const td_api::getFileMimeType &request);
+  static td_api::object_ptr<td_api::Object> do_static_request(const td_api::getFileExtension &request);
+
+  Status init(DbKey key) TD_WARN_UNUSED_RESULT;
+  void clear();
+  void close_impl(bool destroy_flag);
+  Status fix_parameters(TdParameters &parameters) TD_WARN_UNUSED_RESULT;
+  Status set_parameters(td_api::object_ptr<td_api::tdlibParameters> parameters) TD_WARN_UNUSED_RESULT;
+
+  // Actor
+  void start_up() override;
+  void tear_down() override;
+  void hangup_shared() override;
+  void hangup() override;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/TdCallback.h b/libs/tdlib/td/td/telegram/TdCallback.h
new file mode 100644
index 0000000000..eead22c6c9
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/TdCallback.h
@@ -0,0 +1,48 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+///\file
+
+#include "td/telegram/td_api.h"
+
+#include <cstdint>
+
+namespace td {
+
+/**
+ * Interface of callback for low-level interaction with TDLib.
+ */
+class TdCallback {
+ public:
+  /**
+   * This function is called for every answer to a request made to TDLib and for every incoming update of the type td_api::Update.
+   * \param id Request identifier or 0 for incoming updates.
+   * \param result Answer to the TDLib request or an incoming update.
+   */
+  virtual void on_result(std::uint64_t id, td_api::object_ptr<td_api::Object> result) = 0;
+
+  /**
+   * This function is called for every unsuccessful request made to TDLib.
+   * \param id Request identifier.
+   * \param error An answer to a TDLib request or an incoming update.
+   */
+  virtual void on_error(std::uint64_t id, td_api::object_ptr<td_api::error> error) = 0;
+
+  /**
+   * This function is called when TDLib has been fully closed. It's not possible to make any new requests after this function has been called
+   * without creating a new instance of ClientActor. The callback will be destroyed as soon as a call to this function returns.
+   */
+  virtual void on_closed() = 0;
+
+  /**
+   * Destroys the TdCallback.
+   */
+  virtual ~TdCallback() = default;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/TdDb.cpp b/libs/tdlib/td/td/telegram/TdDb.cpp
new file mode 100644
index 0000000000..c642f2d50a
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/TdDb.cpp
@@ -0,0 +1,424 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/TdDb.h"
+
+#include "td/telegram/DialogDb.h"
+#include "td/telegram/files/FileDb.h"
+#include "td/telegram/logevent/LogEvent.h"
+#include "td/telegram/MessagesDb.h"
+#include "td/telegram/TdParameters.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/MultiPromise.h"
+
+#include "td/db/BinlogKeyValue.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/port/path.h"
+#include "td/utils/Random.h"
+
+namespace td {
+namespace {
+std::string get_binlog_path(const TdParameters &parameters) {
+  return PSTRING() << parameters.database_directory << "td" << (parameters.use_test_dc ? "_test" : "") << ".binlog";
+}
+
+std::string get_sqlite_path(const TdParameters &parameters) {
+  const string db_name = "db" + (parameters.use_test_dc ? string("_test") : string());
+  return parameters.database_directory + db_name + ".sqlite";
+}
+
+Result<EncryptionInfo> check_encryption(string path) {
+  Binlog binlog;
+  auto status = binlog.init(path, Binlog::Callback());
+  if (status.is_error() && status.code() != Binlog::Error::WrongPassword) {
+    return Status::Error(400, status.message());
+  }
+  EncryptionInfo info;
+  info.is_encrypted = binlog.get_info().wrong_password;
+  binlog.close(false /*need_sync*/).ensure();
+  return info;
+}
+
+Status init_binlog(Binlog &binlog, string path, BinlogKeyValue<Binlog> &binlog_pmc, BinlogKeyValue<Binlog> &config_pmc,
+                   TdDb::Events &events, DbKey key) {
+  auto callback = [&](const BinlogEvent &event) {
+    switch (event.type_) {
+      case LogEvent::HandlerType::SecretChats:
+        events.to_secret_chats_manager.push_back(event.clone());
+        break;
+      case LogEvent::HandlerType::Users:
+        events.user_events.push_back(event.clone());
+        break;
+      case LogEvent::HandlerType::Chats:
+        events.chat_events.push_back(event.clone());
+        break;
+      case LogEvent::HandlerType::Channels:
+        events.channel_events.push_back(event.clone());
+        break;
+      case LogEvent::HandlerType::SecretChatInfos:
+        events.secret_chat_events.push_back(event.clone());
+        break;
+      case LogEvent::HandlerType::WebPages:
+        events.web_page_events.push_back(event.clone());
+        break;
+      case LogEvent::HandlerType::SendMessage:
+      case LogEvent::HandlerType::DeleteMessage:
+      case LogEvent::HandlerType::DeleteMessagesFromServer:
+      case LogEvent::HandlerType::ReadHistoryOnServer:
+      case LogEvent::HandlerType::ReadMessageContentsOnServer:
+      case LogEvent::HandlerType::ForwardMessages:
+      case LogEvent::HandlerType::SendBotStartMessage:
+      case LogEvent::HandlerType::SendScreenshotTakenNotificationMessage:
+      case LogEvent::HandlerType::SendInlineQueryResultMessage:
+      case LogEvent::HandlerType::DeleteDialogHistoryFromServer:
+      case LogEvent::HandlerType::ReadAllDialogMentionsOnServer:
+      case LogEvent::HandlerType::DeleteAllChannelMessagesFromUserOnServer:
+      case LogEvent::HandlerType::ToggleDialogIsPinnedOnServer:
+      case LogEvent::HandlerType::ReorderPinnedDialogsOnServer:
+      case LogEvent::HandlerType::SaveDialogDraftMessageOnServer:
+      case LogEvent::HandlerType::GetChannelDifference:
+        events.to_messages_manager.push_back(event.clone());
+        break;
+      case LogEvent::HandlerType::BinlogPmcMagic:
+        binlog_pmc.external_init_handle(event);
+        break;
+      case LogEvent::HandlerType::ConfigPmcMagic:
+        config_pmc.external_init_handle(event);
+        break;
+      default:
+        LOG(FATAL) << "Unsupported logevent type " << event.type_;
+    }
+  };
+
+  auto binlog_info = binlog.init(std::move(path), callback, std::move(key));
+  if (binlog_info.is_error()) {
+    return binlog_info.move_as_error();
+  }
+  return Status::OK();
+}
+
+Status init_db(SqliteDb &db) {
+  TRY_STATUS(db.exec("PRAGMA encoding=\"UTF-8\""));
+  TRY_STATUS(db.exec("PRAGMA journal_mode=WAL"));
+
+  TRY_STATUS(db.exec("PRAGMA synchronous=NORMAL"));
+  TRY_STATUS(db.exec("PRAGMA temp_store=MEMORY"));
+  TRY_STATUS(db.exec("PRAGMA secure_delete=1"));
+
+  return Status::OK();
+}
+
+}  // namespace
+
+std::shared_ptr<FileDbInterface> TdDb::get_file_db_shared() {
+  return file_db_;
+}
+std::shared_ptr<SqliteConnectionSafe> &TdDb::get_sqlite_connection_safe() {
+  return sql_connection_;
+}
+ConcurrentBinlog *TdDb::get_binlog() {
+  CHECK(binlog_);
+  return binlog_.get();
+}
+BinlogPmc TdDb::get_binlog_pmc_shared() {
+  return binlog_pmc_;
+}
+BinlogPmcPtr TdDb::get_binlog_pmc() {
+  CHECK(binlog_pmc_);
+  return binlog_pmc_.get();
+}
+BinlogPmcPtr TdDb::get_config_pmc() {
+  CHECK(config_pmc_);
+  return config_pmc_.get();
+}
+
+BigPmcPtr TdDb::get_sqlite_sync_pmc() {
+  CHECK(common_kv_safe_);
+  return &common_kv_safe_->get();
+}
+
+SqliteKeyValueAsyncInterface *TdDb::get_sqlite_pmc() {
+  CHECK(common_kv_async_);
+  return common_kv_async_.get();
+}
+
+MessagesDbSyncInterface *TdDb::get_messages_db_sync() {
+  return &messages_db_sync_safe_->get();
+}
+MessagesDbAsyncInterface *TdDb::get_messages_db_async() {
+  return messages_db_async_.get();
+}
+DialogDbSyncInterface *TdDb::get_dialog_db_sync() {
+  return &dialog_db_sync_safe_->get();
+}
+DialogDbAsyncInterface *TdDb::get_dialog_db_async() {
+  return dialog_db_async_.get();
+}
+
+CSlice TdDb::binlog_path() const {
+  return binlog_->get_path();
+}
+CSlice TdDb::sqlite_path() const {
+  return sqlite_path_;
+}
+
+void TdDb::flush_all() {
+  if (messages_db_async_) {
+    messages_db_async_->force_flush();
+  }
+  binlog_->force_flush();
+}
+void TdDb::close_all(Promise<> on_finished) {
+  do_close(std::move(on_finished), false /*destroy_flag*/);
+}
+
+void TdDb::close_and_destroy_all(Promise<> on_finished) {
+  do_close(std::move(on_finished), true /*destroy_flag*/);
+}
+void TdDb::do_close(Promise<> on_finished, bool destroy_flag) {
+  MultiPromiseActorSafe mpas;
+  mpas.add_promise(PromiseCreator::lambda(
+      [promise = std::move(on_finished), sql_connection = std::move(sql_connection_), destroy_flag](Unit) mutable {
+        if (sql_connection) {
+          CHECK(sql_connection.unique()) << sql_connection.use_count();
+          if (destroy_flag) {
+            sql_connection->close_and_destroy();
+          } else {
+            sql_connection->close();
+          }
+          sql_connection.reset();
+        }
+        promise.set_value(Unit());
+      }));
+  auto lock = mpas.get_promise();
+
+  if (file_db_) {
+    file_db_->close(mpas.get_promise());
+    file_db_.reset();
+  }
+
+  common_kv_safe_.reset();
+  if (common_kv_async_) {
+    common_kv_async_->close(mpas.get_promise());
+  }
+
+  messages_db_sync_safe_.reset();
+  if (messages_db_async_) {
+    messages_db_async_->close(mpas.get_promise());
+  }
+
+  dialog_db_sync_safe_.reset();
+  if (dialog_db_async_) {
+    dialog_db_async_->close(mpas.get_promise());
+  }
+
+  // binlog_pmc is dependent on binlog_ and anyway it doesn't support close_and_destroy
+  CHECK(binlog_pmc_.unique());
+  binlog_pmc_.reset();
+  CHECK(config_pmc_.unique());
+  config_pmc_.reset();
+
+  if (binlog_) {
+    if (destroy_flag) {
+      binlog_->close_and_destroy(mpas.get_promise());
+    } else {
+      binlog_->close(mpas.get_promise());
+    }
+    binlog_.reset();
+  }
+}
+
+Status TdDb::init_sqlite(int32 scheduler_id, const TdParameters &parameters, DbKey key, DbKey old_key,
+                         BinlogKeyValue<Binlog> &binlog_pmc) {
+  CHECK(!parameters.use_message_db || parameters.use_chat_info_db);
+  CHECK(!parameters.use_chat_info_db || parameters.use_file_db);
+
+  const string sql_db_name = get_sqlite_path(parameters);
+
+  bool use_sqlite = parameters.use_file_db;
+  bool use_file_db = parameters.use_file_db;
+  bool use_dialog_db = parameters.use_message_db;
+  bool use_message_db = parameters.use_message_db;
+  if (!use_sqlite) {
+    unlink(sql_db_name).ignore();
+    return Status::OK();
+  }
+
+  sqlite_path_ = sql_db_name;
+  TRY_STATUS(SqliteDb::change_key(sqlite_path_, key, old_key));
+  sql_connection_ = std::make_shared<SqliteConnectionSafe>(sql_db_name, key);
+  auto &db = sql_connection_->get();
+
+  TRY_STATUS(init_db(db));
+
+  // Init databases
+  // Do initialization once and before everything else to avoid "database is locked" error.
+  // Must be in a transaction
+
+  // NB: when database is dropped we should also drop corresponding binlog events
+  TRY_STATUS(db.exec("BEGIN TRANSACTION"));
+
+  // Get 'PRAGMA user_version'
+  TRY_RESULT(user_version, db.user_version());
+  LOG(WARNING) << "got PRAGMA user_version = " << user_version;
+
+  // init DialogDb
+  bool dialog_db_was_created = false;
+  if (use_dialog_db) {
+    TRY_STATUS(init_dialog_db(db, user_version, dialog_db_was_created));
+  } else {
+    TRY_STATUS(drop_dialog_db(db, user_version));
+  }
+
+  // init MessagesDb
+  if (use_message_db) {
+    TRY_STATUS(init_messages_db(db, user_version));
+  } else {
+    TRY_STATUS(drop_messages_db(db, user_version));
+  }
+
+  // init filesDb
+  if (use_file_db) {
+    TRY_STATUS(init_file_db(db, user_version));
+  } else {
+    TRY_STATUS(drop_file_db(db, user_version));
+  }
+
+  // Update 'PRAGMA user_version'
+  auto db_version = current_db_version();
+  if (db_version != user_version) {
+    LOG(WARNING) << "set PRAGMA user_version = " << db_version;
+    TRY_STATUS(db.set_user_version(db_version));
+  }
+
+  if (dialog_db_was_created) {
+    binlog_pmc.erase("unread_message_count");
+    binlog_pmc.erase("last_server_dialog_date");
+  }
+  if (db_version == 0) {
+    binlog_pmc.erase_by_prefix("top_dialogs");
+    binlog_pmc.erase("next_contacts_sync_date");
+  }
+  binlog_pmc.force_sync({});
+
+  TRY_STATUS(db.exec("COMMIT TRANSACTION"));
+
+  file_db_ = create_file_db(sql_connection_, scheduler_id);
+
+  common_kv_safe_ = std::make_shared<SqliteKeyValueSafe>("common", sql_connection_);
+  common_kv_async_ = create_sqlite_key_value_async(common_kv_safe_, scheduler_id);
+
+  if (use_dialog_db) {
+    dialog_db_sync_safe_ = create_dialog_db_sync(sql_connection_);
+    dialog_db_async_ = create_dialog_db_async(dialog_db_sync_safe_, scheduler_id);
+  }
+
+  if (use_message_db) {
+    messages_db_sync_safe_ = create_messages_db_sync(sql_connection_);
+    messages_db_async_ = create_messages_db_async(messages_db_sync_safe_, scheduler_id);
+  }
+
+  return Status::OK();
+}
+
+Status TdDb::init(int32 scheduler_id, const TdParameters &parameters, DbKey key, Events &events) {
+  // Init pmc
+  Binlog *binlog_ptr = nullptr;
+  auto binlog = std::shared_ptr<Binlog>(new Binlog, [&](Binlog *ptr) { binlog_ptr = ptr; });
+
+  auto binlog_pmc = std::make_unique<BinlogKeyValue<Binlog>>();
+  auto config_pmc = std::make_unique<BinlogKeyValue<Binlog>>();
+  binlog_pmc->external_init_begin(static_cast<int32>(LogEvent::HandlerType::BinlogPmcMagic));
+  config_pmc->external_init_begin(static_cast<int32>(LogEvent::HandlerType::ConfigPmcMagic));
+
+  bool encrypt_binlog = !key.is_empty();
+  TRY_STATUS(init_binlog(*binlog, get_binlog_path(parameters), *binlog_pmc, *config_pmc, events, std::move(key)));
+
+  binlog_pmc->external_init_finish(binlog);
+  config_pmc->external_init_finish(binlog);
+
+  DbKey new_sqlite_key;
+  DbKey old_sqlite_key;
+  bool encrypt_sqlite = encrypt_binlog;
+  bool drop_sqlite_key = false;
+  auto sqlite_key = binlog_pmc->get("sqlite_key");
+  if (encrypt_sqlite) {
+    if (sqlite_key.empty()) {
+      sqlite_key = string(32, ' ');
+      Random::secure_bytes(sqlite_key);
+      binlog_pmc->set("sqlite_key", sqlite_key);
+      binlog_pmc->force_sync(Auto());
+    }
+    new_sqlite_key = DbKey::raw_key(std::move(sqlite_key));
+  } else {
+    if (!sqlite_key.empty()) {
+      old_sqlite_key = DbKey::raw_key(std::move(sqlite_key));
+      drop_sqlite_key = true;
+    }
+  }
+  auto init_sqlite_status = init_sqlite(scheduler_id, parameters, new_sqlite_key, old_sqlite_key, *binlog_pmc);
+  if (init_sqlite_status.is_error()) {
+    LOG(ERROR) << "Destroy bad sqlite db because of: " << init_sqlite_status;
+    SqliteDb::destroy(get_sqlite_path(parameters)).ignore();
+    TRY_STATUS(init_sqlite(scheduler_id, parameters, new_sqlite_key, old_sqlite_key, *binlog_pmc));
+  }
+  if (drop_sqlite_key) {
+    binlog_pmc->erase("sqlite_key");
+    binlog_pmc->force_sync(Auto());
+  }
+
+  auto concurrent_binlog_pmc = std::make_shared<BinlogKeyValue<ConcurrentBinlog>>();
+  concurrent_binlog_pmc->external_init_begin(binlog_pmc->get_magic());
+  concurrent_binlog_pmc->external_init_handle(std::move(*binlog_pmc));
+
+  auto concurrent_config_pmc = std::make_shared<BinlogKeyValue<ConcurrentBinlog>>();
+  concurrent_config_pmc->external_init_begin(config_pmc->get_magic());
+  concurrent_config_pmc->external_init_handle(std::move(*config_pmc));
+
+  binlog.reset();
+  binlog_pmc.reset();
+  config_pmc.reset();
+
+  CHECK(binlog_ptr != nullptr);
+  auto concurrent_binlog = std::make_shared<ConcurrentBinlog>(std::unique_ptr<Binlog>(binlog_ptr), scheduler_id);
+
+  concurrent_binlog_pmc->external_init_finish(concurrent_binlog);
+  concurrent_config_pmc->external_init_finish(concurrent_binlog);
+
+  binlog_pmc_ = std::move(concurrent_binlog_pmc);
+  config_pmc_ = std::move(concurrent_config_pmc);
+  binlog_ = std::move(concurrent_binlog);
+
+  return Status::OK();
+}
+
+TdDb::TdDb() = default;
+TdDb::~TdDb() = default;
+
+Result<std::unique_ptr<TdDb>> TdDb::open(int32 scheduler_id, const TdParameters &parameters, DbKey key,
+                                         Events &events) {
+  auto db = std::make_unique<TdDb>();
+  TRY_STATUS(db->init(scheduler_id, parameters, std::move(key), events));
+  return std::move(db);
+}
+Result<EncryptionInfo> TdDb::check_encryption(const TdParameters &parameters) {
+  return ::td::check_encryption(get_binlog_path(parameters));
+}
+void TdDb::change_key(DbKey key, Promise<> promise) {
+  get_binlog()->change_key(std::move(key), std::move(promise));
+}
+Status TdDb::destroy(const TdParameters &parameters) {
+  SqliteDb::destroy(get_sqlite_path(parameters)).ignore();
+  Binlog::destroy(get_binlog_path(parameters)).ignore();
+  return Status::OK();
+}
+void TdDb::with_db_path(std::function<void(CSlice)> callback) {
+  SqliteDb::with_db_path(sqlite_path(), callback);
+  callback(binlog_path());
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/TdDb.h b/libs/tdlib/td/td/telegram/TdDb.h
new file mode 100644
index 0000000000..dbb219ec01
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/TdDb.h
@@ -0,0 +1,121 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/db/binlog/Binlog.h"
+#include "td/db/binlog/BinlogEvent.h"
+#include "td/db/binlog/ConcurrentBinlog.h"
+#include "td/db/BinlogKeyValue.h"
+#include "td/db/DbKey.h"
+#include "td/db/Pmc.h"
+#include "td/db/SqliteKeyValue.h"
+#include "td/db/SqliteKeyValueAsync.h"
+#include "td/db/SqliteKeyValueSafe.h"
+
+#include "td/telegram/TdParameters.h"
+
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <functional>
+#include <memory>
+
+namespace td {
+
+class SqliteConnectionSafe;
+class SqliteKeyValueSafe;
+class SqliteKeyValueAsyncInterface;
+class SqliteKeyValue;
+class MessagesDbSyncInterface;
+class MessagesDbSyncSafeInterface;
+class MessagesDbAsyncInterface;
+class DialogDbSyncInterface;
+class DialogDbSyncSafeInterface;
+class DialogDbAsyncInterface;
+class FileDbInterface;
+
+struct EncryptionInfo {
+  bool is_encrypted{false};
+};
+
+class TdDb {
+ public:
+  TdDb();
+  TdDb(const TdDb &) = delete;
+  TdDb &operator=(const TdDb &) = delete;
+  TdDb(TdDb &&) = delete;
+  TdDb &operator=(TdDb &&) = delete;
+  ~TdDb();
+
+  struct Events;
+  static Result<std::unique_ptr<TdDb>> open(int32 scheduler_id, const TdParameters &parameters, DbKey key,
+                                            Events &events);
+  static Result<EncryptionInfo> check_encryption(const TdParameters &parameters);
+  static Status destroy(const TdParameters &parameters);
+
+  struct Events {
+    vector<BinlogEvent> to_secret_chats_manager;
+    vector<BinlogEvent> user_events;
+    vector<BinlogEvent> chat_events;
+    vector<BinlogEvent> channel_events;
+    vector<BinlogEvent> secret_chat_events;
+    vector<BinlogEvent> web_page_events;
+    vector<BinlogEvent> to_messages_manager;
+  };
+
+  std::shared_ptr<FileDbInterface> get_file_db_shared();
+  std::shared_ptr<SqliteConnectionSafe> &get_sqlite_connection_safe();
+  ConcurrentBinlog *get_binlog();
+
+  BinlogPmc get_binlog_pmc_shared();
+  BinlogPmcPtr get_binlog_pmc();
+  BinlogPmcPtr get_config_pmc();
+
+  BigPmcPtr get_sqlite_sync_pmc();
+  SqliteKeyValueAsyncInterface *get_sqlite_pmc();
+  CSlice binlog_path() const;
+  CSlice sqlite_path() const;
+  void flush_all();
+  void close_all(Promise<> on_finished);
+  void close_and_destroy_all(Promise<> on_finished);
+
+  MessagesDbSyncInterface *get_messages_db_sync();
+  MessagesDbAsyncInterface *get_messages_db_async();
+
+  DialogDbSyncInterface *get_dialog_db_sync();
+  DialogDbAsyncInterface *get_dialog_db_async();
+
+  void change_key(DbKey key, Promise<> promise);
+
+  void with_db_path(std::function<void(CSlice)> callback);
+
+ private:
+  string sqlite_path_;
+  std::shared_ptr<SqliteConnectionSafe> sql_connection_;
+
+  std::shared_ptr<FileDbInterface> file_db_;
+
+  std::shared_ptr<SqliteKeyValueSafe> common_kv_safe_;
+  std::unique_ptr<SqliteKeyValueAsyncInterface> common_kv_async_;
+
+  std::shared_ptr<MessagesDbSyncSafeInterface> messages_db_sync_safe_;
+  std::shared_ptr<MessagesDbAsyncInterface> messages_db_async_;
+
+  std::shared_ptr<DialogDbSyncSafeInterface> dialog_db_sync_safe_;
+  std::shared_ptr<DialogDbAsyncInterface> dialog_db_async_;
+
+  std::shared_ptr<BinlogKeyValue<ConcurrentBinlog>> binlog_pmc_;
+  std::shared_ptr<BinlogKeyValue<ConcurrentBinlog>> config_pmc_;
+  std::shared_ptr<ConcurrentBinlog> binlog_;
+
+  Status init(int32 scheduler_id, const TdParameters &parameters, DbKey key, Events &events);
+  Status init_sqlite(int32 scheduler_id, const TdParameters &parameters, DbKey key, DbKey old_key,
+                     BinlogKeyValue<Binlog> &binlog_pmc);
+
+  void do_close(Promise<> on_finished, bool destroy_flag);
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/TdParameters.h b/libs/tdlib/td/td/telegram/TdParameters.h
new file mode 100644
index 0000000000..b89022910e
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/TdParameters.h
@@ -0,0 +1,28 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include <cstdint>
+#include <string>
+
+namespace td {
+
+struct TdParameters {
+  bool use_test_dc = false;
+  std::string database_directory;
+  std::string files_directory;
+  std::int32_t api_id = 0;
+  std::string api_hash;
+  bool use_file_db = true;
+  bool enable_storage_optimizer = false;
+  bool ignore_file_names = false;
+  bool use_secret_chats = false;
+  bool use_chat_info_db = false;
+  bool use_message_db = false;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/TopDialogManager.cpp b/libs/tdlib/td/td/telegram/TopDialogManager.cpp
new file mode 100644
index 0000000000..02a9d7baac
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/TopDialogManager.cpp
@@ -0,0 +1,468 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/TopDialogManager.h"
+
+#include "td/telegram/ConfigShared.h"
+#include "td/telegram/ContactsManager.h"
+#include "td/telegram/DialogId.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/logevent/LogEvent.h"
+#include "td/telegram/MessagesManager.h"
+#include "td/telegram/misc.h"
+#include "td/telegram/net/NetQuery.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+#include "td/telegram/StateManager.h"
+#include "td/telegram/Td.h"
+
+#include "td/utils/misc.h"
+#include "td/utils/port/Clocks.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/tl_helpers.h"
+
+#include "td/telegram/telegram_api.h"
+
+#include <algorithm>
+#include <cmath>
+#include <iterator>
+
+namespace td {
+
+static CSlice top_dialog_category_name(TopDialogCategory category) {
+  switch (category) {
+    case TopDialogCategory::Correspondent:
+      return CSlice("correspondent");
+    case TopDialogCategory::BotPM:
+      return CSlice("bot_pm");
+    case TopDialogCategory::BotInline:
+      return CSlice("bot_inline");
+    case TopDialogCategory::Group:
+      return CSlice("group");
+    case TopDialogCategory::Channel:
+      return CSlice("channel");
+    case TopDialogCategory::Call:
+      return CSlice("call");
+    default:
+      UNREACHABLE();
+  }
+}
+
+static TopDialogCategory top_dialog_category_from_telegram_api(const telegram_api::TopPeerCategory &category) {
+  switch (category.get_id()) {
+    case telegram_api::topPeerCategoryCorrespondents::ID:
+      return TopDialogCategory::Correspondent;
+    case telegram_api::topPeerCategoryBotsPM::ID:
+      return TopDialogCategory::BotPM;
+    case telegram_api::topPeerCategoryBotsInline::ID:
+      return TopDialogCategory::BotInline;
+    case telegram_api::topPeerCategoryGroups::ID:
+      return TopDialogCategory::Group;
+    case telegram_api::topPeerCategoryChannels::ID:
+      return TopDialogCategory::Channel;
+    case telegram_api::topPeerCategoryPhoneCalls::ID:
+      return TopDialogCategory::Call;
+    default:
+      UNREACHABLE();
+  }
+}
+
+static tl_object_ptr<telegram_api::TopPeerCategory> top_dialog_category_as_telegram_api(TopDialogCategory category) {
+  switch (category) {
+    case TopDialogCategory::Correspondent:
+      return make_tl_object<telegram_api::topPeerCategoryCorrespondents>();
+    case TopDialogCategory::BotPM:
+      return make_tl_object<telegram_api::topPeerCategoryBotsPM>();
+    case TopDialogCategory::BotInline:
+      return make_tl_object<telegram_api::topPeerCategoryBotsInline>();
+    case TopDialogCategory::Group:
+      return make_tl_object<telegram_api::topPeerCategoryGroups>();
+    case TopDialogCategory::Channel:
+      return make_tl_object<telegram_api::topPeerCategoryChannels>();
+    case TopDialogCategory::Call:
+      return make_tl_object<telegram_api::topPeerCategoryPhoneCalls>();
+    default:
+      UNREACHABLE();
+  }
+}
+
+void TopDialogManager::on_dialog_used(TopDialogCategory category, DialogId dialog_id, int32 date) {
+  if (!is_active_) {
+    return;
+  }
+  auto pos = static_cast<size_t>(category);
+  CHECK(pos < by_category_.size());
+  auto &top_dialogs = by_category_[pos];
+
+  top_dialogs.is_dirty = true;
+  auto it = std::find_if(top_dialogs.dialogs.begin(), top_dialogs.dialogs.end(),
+                         [&](auto &top_dialog) { return top_dialog.dialog_id == dialog_id; });
+  if (it == top_dialogs.dialogs.end()) {
+    TopDialog top_dialog;
+    top_dialog.dialog_id = dialog_id;
+    top_dialogs.dialogs.push_back(top_dialog);
+    it = top_dialogs.dialogs.end() - 1;
+  }
+
+  auto delta = rating_add(date, top_dialogs.rating_timestamp);
+  it->rating += delta;
+  while (it != top_dialogs.dialogs.begin()) {
+    auto next = std::prev(it);
+    if (*next < *it) {
+      break;
+    }
+    std::swap(*next, *it);
+    it = next;
+  }
+
+  LOG(INFO) << "Update " << top_dialog_category_name(category) << " rating of " << dialog_id << " by " << delta;
+
+  if (!first_unsync_change_) {
+    first_unsync_change_ = Timestamp::now_cached();
+  }
+  loop();
+}
+
+void TopDialogManager::remove_dialog(TopDialogCategory category, DialogId dialog_id,
+                                     tl_object_ptr<telegram_api::InputPeer> input_peer) {
+  if (!is_active_) {
+    return;
+  }
+
+  auto pos = static_cast<size_t>(category);
+  CHECK(pos < by_category_.size());
+  auto &top_dialogs = by_category_[pos];
+
+  LOG(INFO) << "Remove " << top_dialog_category_name(category) << " rating of " << dialog_id;
+
+  if (input_peer != nullptr) {
+    auto query =
+        telegram_api::contacts_resetTopPeerRating(top_dialog_category_as_telegram_api(category), std::move(input_peer));
+    auto net_query = G()->net_query_creator().create(create_storer(query));
+    G()->net_query_dispatcher().dispatch_with_callback(std::move(net_query), actor_shared(this, 1));
+  }
+
+  auto it = std::find_if(top_dialogs.dialogs.begin(), top_dialogs.dialogs.end(),
+                         [&](auto &top_dialog) { return top_dialog.dialog_id == dialog_id; });
+  if (it == top_dialogs.dialogs.end()) {
+    return;
+  }
+
+  top_dialogs.is_dirty = true;
+  top_dialogs.dialogs.erase(it);
+  if (!first_unsync_change_) {
+    first_unsync_change_ = Timestamp::now_cached();
+  }
+  loop();
+}
+
+void TopDialogManager::get_top_dialogs(TopDialogCategory category, size_t limit, Promise<vector<DialogId>> promise) {
+  if (!is_active_) {
+    promise.set_error(Status::Error(400, "Not supported without chat info database"));
+    return;
+  }
+  GetTopDialogsQuery query;
+  query.category = category;
+  query.limit = limit;
+  query.promise = std::move(promise);
+  pending_get_top_dialogs_.push_back(std::move(query));
+  loop();
+}
+
+void TopDialogManager::update_rating_e_decay() {
+  if (!is_active_) {
+    return;
+  }
+  rating_e_decay_ = G()->shared_config().get_option_integer("rating_e_decay", rating_e_decay_);
+}
+
+template <class T>
+void parse(TopDialogManager::TopDialog &top_dialog, T &parser) {
+  using ::td::parse;
+  parse(top_dialog.dialog_id, parser);
+  parse(top_dialog.rating, parser);
+}
+
+template <class T>
+void store(const TopDialogManager::TopDialog &top_dialog, T &storer) {
+  using ::td::store;
+  store(top_dialog.dialog_id, storer);
+  store(top_dialog.rating, storer);
+}
+
+template <class T>
+void parse(TopDialogManager::TopDialogs &top_dialogs, T &parser) {
+  using ::td::parse;
+  parse(top_dialogs.rating_timestamp, parser);
+  parse(top_dialogs.dialogs, parser);
+}
+
+template <class T>
+void store(const TopDialogManager::TopDialogs &top_dialogs, T &storer) {
+  using ::td::store;
+  store(top_dialogs.rating_timestamp, storer);
+  store(top_dialogs.dialogs, storer);
+}
+
+double TopDialogManager::rating_add(double now, double rating_timestamp) const {
+  return std::exp((now - rating_timestamp) / rating_e_decay_);
+}
+
+double TopDialogManager::current_rating_add(double rating_timestamp) const {
+  return rating_add(G()->server_time_cached(), rating_timestamp);
+}
+
+void TopDialogManager::normalize_rating() {
+  for (auto &top_dialogs : by_category_) {
+    auto div_by = current_rating_add(top_dialogs.rating_timestamp);
+    top_dialogs.rating_timestamp = G()->server_time_cached();
+    for (auto &dialog : top_dialogs.dialogs) {
+      dialog.rating /= div_by;
+    }
+    top_dialogs.is_dirty = true;
+  }
+  db_sync_state_ = SyncState::None;
+}
+
+void TopDialogManager::do_get_top_dialogs(GetTopDialogsQuery &&query) {
+  auto pos = static_cast<size_t>(query.category);
+  CHECK(pos < by_category_.size());
+  auto &top_dialogs = by_category_[pos];
+
+  auto limit = std::min({query.limit, MAX_TOP_DIALOGS_LIMIT, top_dialogs.dialogs.size()});
+
+  vector<DialogId> dialog_ids = transform(top_dialogs.dialogs, [](const auto &x) { return x.dialog_id; });
+
+  auto promise = PromiseCreator::lambda([query = std::move(query), dialog_ids, limit](Result<Unit>) mutable {
+    vector<DialogId> result;
+    result.reserve(limit);
+    for (auto dialog_id : dialog_ids) {
+      if (dialog_id.get_type() == DialogType::User) {
+        auto user_id = dialog_id.get_user_id();
+        if (G()->td().get_actor_unsafe()->contacts_manager_->is_user_deleted(user_id)) {
+          LOG(INFO) << "Skip deleted " << user_id;
+          continue;
+        }
+        if (G()->td().get_actor_unsafe()->contacts_manager_->get_my_id("do_get_top_dialogs") == user_id) {
+          LOG(INFO) << "Skip self " << user_id;
+          continue;
+        }
+      }
+
+      result.push_back(dialog_id);
+      if (result.size() == limit) {
+        break;
+      }
+    }
+
+    query.promise.set_value(std::move(result));
+  });
+  send_closure(G()->messages_manager(), &MessagesManager::load_dialogs, std::move(dialog_ids), std::move(promise));
+}
+
+void TopDialogManager::do_get_top_peers() {
+  LOG(INFO) << "Send get top peers request";
+  using telegram_api::contacts_getTopPeers;
+
+  std::vector<uint32> ids;
+  for (auto &category : by_category_) {
+    for (auto &top_dialog : category.dialogs) {
+      auto dialog_id = top_dialog.dialog_id;
+      switch (dialog_id.get_type()) {
+        case DialogType::Channel:
+          ids.push_back(dialog_id.get_channel_id().get());
+          break;
+        case DialogType::User:
+          ids.push_back(dialog_id.get_user_id().get());
+          break;
+        case DialogType::Chat:
+          ids.push_back(dialog_id.get_chat_id().get());
+          break;
+        default:
+          break;
+      }
+    }
+  }
+
+  int32 hash = get_vector_hash(ids);
+
+  int32 flags = contacts_getTopPeers::CORRESPONDENTS_MASK | contacts_getTopPeers::BOTS_PM_MASK |
+                contacts_getTopPeers::BOTS_INLINE_MASK | contacts_getTopPeers::GROUPS_MASK |
+                contacts_getTopPeers::CHANNELS_MASK | contacts_getTopPeers::PHONE_CALLS_MASK;
+
+  contacts_getTopPeers query{
+      flags,           true /*correspondents*/, true /*bot_pm*/, true /*bot_inline */, true /*phone_calls*/,
+      true /*groups*/, true /*channels*/,       0 /*offset*/,    100 /*limit*/,        hash};
+  auto net_query = G()->net_query_creator().create(create_storer(query));
+  G()->net_query_dispatcher().dispatch_with_callback(std::move(net_query), actor_shared(this));
+}
+
+void TopDialogManager::on_result(NetQueryPtr net_query) {
+  if (get_link_token() == 1) {
+    return;
+  }
+  SCOPE_EXIT {
+    loop();
+  };
+  normalize_rating();  // once a day too
+  last_server_sync_ = Timestamp::now();
+  server_sync_state_ = SyncState::Ok;
+  G()->td_db()->get_binlog_pmc()->set("top_dialogs_ts", to_string(static_cast<uint32>(Clocks::system())));
+
+  auto r_top_peers = fetch_result<telegram_api::contacts_getTopPeers>(std::move(net_query));
+  if (r_top_peers.is_error()) {
+    LOG(ERROR) << "contacts_getTopPeers failed: " << r_top_peers.error();
+    return;
+  }
+  auto top_peers_parent = r_top_peers.move_as_ok();
+  LOG(INFO) << "contacts_getTopPeers returned " << to_string(top_peers_parent);
+  if (top_peers_parent->get_id() == telegram_api::contacts_topPeersNotModified::ID) {
+    return;
+  }
+
+  CHECK(top_peers_parent->get_id() == telegram_api::contacts_topPeers::ID);
+  auto top_peers = move_tl_object_as<telegram_api::contacts_topPeers>(std::move(top_peers_parent));
+
+  send_closure(G()->contacts_manager(), &ContactsManager::on_get_users, std::move(top_peers->users_));
+  send_closure(G()->contacts_manager(), &ContactsManager::on_get_chats, std::move(top_peers->chats_));
+  for (auto &category : top_peers->categories_) {
+    auto dialog_category = top_dialog_category_from_telegram_api(*category->category_);
+    auto pos = static_cast<size_t>(dialog_category);
+    CHECK(pos < by_category_.size());
+    auto &top_dialogs = by_category_[pos];
+
+    top_dialogs.is_dirty = true;
+    top_dialogs.dialogs.clear();
+    for (auto &top_peer : category->peers_) {
+      TopDialog top_dialog;
+      top_dialog.dialog_id = DialogId(top_peer->peer_);
+      top_dialog.rating = top_peer->rating_;
+      top_dialogs.dialogs.push_back(std::move(top_dialog));
+    }
+  }
+  db_sync_state_ = SyncState::None;
+}
+
+void TopDialogManager::do_save_top_dialogs() {
+  LOG(INFO) << "Save top chats";
+  for (size_t top_dialog_category_i = 0; top_dialog_category_i < by_category_.size(); top_dialog_category_i++) {
+    auto top_dialog_category = TopDialogCategory(top_dialog_category_i);
+    auto key = PSTRING() << "top_dialogs#" << top_dialog_category_name(top_dialog_category);
+
+    auto &top_dialogs = by_category_[top_dialog_category_i];
+    if (!top_dialogs.is_dirty) {
+      continue;
+    }
+    top_dialogs.is_dirty = false;
+
+    G()->td_db()->get_binlog_pmc()->set(key, log_event_store(top_dialogs).as_slice().str());
+  }
+  db_sync_state_ = SyncState::Ok;
+  first_unsync_change_ = Timestamp();
+}
+
+void TopDialogManager::start_up() {
+  if (!G()->parameters().use_chat_info_db) {
+    G()->td_db()->get_binlog_pmc()->erase_by_prefix("top_dialogs");
+    is_active_ = false;
+    return;
+  }
+  is_active_ = true;
+
+  auto di_top_dialogs_ts = G()->td_db()->get_binlog_pmc()->get("top_dialogs_ts");
+  if (!di_top_dialogs_ts.empty()) {
+    last_server_sync_ = Timestamp::in(to_integer<uint32>(di_top_dialogs_ts) - Clocks::system());
+    if (last_server_sync_.is_in_past()) {
+      server_sync_state_ = SyncState::Ok;
+    }
+  }
+  update_rating_e_decay();
+
+  for (size_t top_dialog_category_i = 0; top_dialog_category_i < by_category_.size(); top_dialog_category_i++) {
+    auto top_dialog_category = TopDialogCategory(top_dialog_category_i);
+    auto key = PSTRING() << "top_dialogs#" << top_dialog_category_name(top_dialog_category);
+    auto value = G()->td_db()->get_binlog_pmc()->get(key);
+
+    auto &top_dialogs = by_category_[top_dialog_category_i];
+    top_dialogs.is_dirty = false;
+    if (value.empty()) {
+      continue;
+    }
+    log_event_parse(top_dialogs, value).ensure();
+  }
+  normalize_rating();
+  db_sync_state_ = SyncState::Ok;
+
+  send_closure(G()->state_manager(), &StateManager::wait_first_sync,
+               PromiseCreator::event(self_closure(this, &TopDialogManager::on_first_sync)));
+
+  loop();
+}
+
+void TopDialogManager::on_first_sync() {
+  was_first_sync_ = true;
+  loop();
+}
+
+void TopDialogManager::loop() {
+  if (!is_active_) {
+    return;
+  }
+
+  if (!pending_get_top_dialogs_.empty()) {
+    for (auto &query : pending_get_top_dialogs_) {
+      do_get_top_dialogs(std::move(query));
+    }
+    pending_get_top_dialogs_.clear();
+  }
+
+  // server sync
+  Timestamp server_sync_timeout;
+  if (server_sync_state_ == SyncState::Ok) {
+    server_sync_timeout = Timestamp::at(last_server_sync_.at() + SERVER_SYNC_DELAY);
+    if (server_sync_timeout.is_in_past()) {
+      server_sync_state_ = SyncState::None;
+    }
+  }
+
+  Timestamp wakeup_timeout;
+  if (server_sync_state_ == SyncState::Ok) {
+    wakeup_timeout.relax(server_sync_timeout);
+  } else if (server_sync_state_ == SyncState::None && was_first_sync_) {
+    server_sync_state_ = SyncState::Pending;
+    do_get_top_peers();
+  }
+
+  // db sync
+  Timestamp db_sync_timeout;
+  if (db_sync_state_ == SyncState::Ok) {
+    if (first_unsync_change_) {
+      db_sync_timeout = Timestamp::at(first_unsync_change_.at() + DB_SYNC_DELAY);
+      if (db_sync_timeout.is_in_past()) {
+        db_sync_state_ = SyncState::None;
+      }
+    }
+  }
+
+  if (db_sync_state_ == SyncState::Ok) {
+    wakeup_timeout.relax(db_sync_timeout);
+  } else if (db_sync_state_ == SyncState::None) {
+    if (server_sync_state_ == SyncState::Ok) {
+      do_save_top_dialogs();
+    }
+  }
+
+  if (wakeup_timeout) {
+    LOG(INFO) << "Wakeup in: " << wakeup_timeout.in();
+    set_timeout_at(wakeup_timeout.at());
+  } else {
+    LOG(INFO) << "Wakeup: never";
+    cancel_timeout();
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/TopDialogManager.h b/libs/tdlib/td/td/telegram/TopDialogManager.h
new file mode 100644
index 0000000000..c301e4252e
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/TopDialogManager.h
@@ -0,0 +1,123 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/DialogId.h"
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/Time.h"
+
+#include <array>
+#include <utility>
+
+namespace td {
+enum class TopDialogCategory { Correspondent, BotPM, BotInline, Group, Channel, Call, Size };
+
+inline TopDialogCategory top_dialog_category_from_td_api(const td_api::TopChatCategory &category) {
+  switch (category.get_id()) {
+    case td_api::topChatCategoryUsers::ID:
+      return TopDialogCategory::Correspondent;
+    case td_api::topChatCategoryBots::ID:
+      return TopDialogCategory::BotPM;
+    case td_api::topChatCategoryInlineBots::ID:
+      return TopDialogCategory::BotInline;
+    case td_api::topChatCategoryGroups::ID:
+      return TopDialogCategory::Group;
+    case td_api::topChatCategoryChannels::ID:
+      return TopDialogCategory::Channel;
+    case td_api::topChatCategoryCalls::ID:
+      return TopDialogCategory::Call;
+    default:
+      UNREACHABLE();
+  }
+}
+
+class TopDialogManager : public NetQueryCallback {
+ public:
+  explicit TopDialogManager(ActorShared<> parent) : parent_(std::move(parent)) {
+  }
+
+  void on_dialog_used(TopDialogCategory category, DialogId dialog_id, int32 date);
+
+  void remove_dialog(TopDialogCategory category, DialogId dialog_id, tl_object_ptr<telegram_api::InputPeer> input_peer);
+
+  void get_top_dialogs(TopDialogCategory category, size_t limit, Promise<vector<DialogId>> promise);
+
+  void update_rating_e_decay();
+
+ private:
+  static constexpr size_t MAX_TOP_DIALOGS_LIMIT = 30;
+  static constexpr int32 SERVER_SYNC_DELAY = 86400;  // seconds
+  static constexpr int32 DB_SYNC_DELAY = 5;          // seconds
+  ActorShared<> parent_;
+
+  bool is_active_{false};
+  bool was_first_sync_{false};
+  enum class SyncState { None, Pending, Ok };
+  SyncState db_sync_state_ = SyncState::None;
+  Timestamp first_unsync_change_;
+  SyncState server_sync_state_ = SyncState::None;
+  Timestamp last_server_sync_;
+
+  struct GetTopDialogsQuery {
+    TopDialogCategory category;
+    size_t limit;
+    Promise<vector<DialogId>> promise;
+  };
+  std::vector<GetTopDialogsQuery> pending_get_top_dialogs_;
+
+  struct TopDialog {
+    DialogId dialog_id;
+    double rating = 0;
+    bool operator<(const TopDialog &other) const {
+      return std::make_pair(-rating, dialog_id.get()) < std::make_pair(-other.rating, other.dialog_id.get());
+    }
+  };
+
+  struct TopDialogs {
+    bool is_dirty = false;
+    double rating_timestamp = 0;
+    std::vector<TopDialog> dialogs;
+  };
+  template <class T>
+  friend void parse(TopDialog &top_dialog, T &parser);
+  template <class T>
+  friend void store(const TopDialog &top_dialog, T &storer);
+  template <class T>
+  friend void parse(TopDialogs &top_dialogs, T &parser);
+  template <class T>
+  friend void store(const TopDialogs &top_dialogs, T &storer);
+
+  std::array<TopDialogs, static_cast<size_t>(TopDialogCategory::Size)> by_category_;
+
+  double rating_add(double now, double rating_timestamp) const;
+  double current_rating_add(double rating_timestamp) const;
+  void normalize_rating();
+
+  int32 rating_e_decay_ = 241920;
+
+  void do_get_top_dialogs(GetTopDialogsQuery &&query);
+
+  void do_get_top_peers();
+  void do_save_top_dialogs();
+
+  void on_first_sync();
+
+  void on_result(NetQueryPtr net_query) override;
+
+  void start_up() override;
+  void loop() override;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/UniqueId.h b/libs/tdlib/td/td/telegram/UniqueId.h
new file mode 100644
index 0000000000..746a6c3ba8
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/UniqueId.h
@@ -0,0 +1,38 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+#include <atomic>
+
+namespace td {
+
+class UniqueId {
+ public:
+  enum Type : uint8 { Default, DcAuth, GetConfig, BindKey, TempFile };
+  static uint64 next() {
+    return next(Default, 0);
+  }
+  static uint64 next(Type type) {
+    return next(type, 0);
+  }
+  static uint64 next(Type type, uint8 key) {
+    // TODO: this is VERY ineffective
+    static std::atomic<uint64> current_id{1};
+    return ((current_id.fetch_add(1, std::memory_order_relaxed)) << 16) | (static_cast<uint64>(type) << 8) | key;
+  }
+
+  static uint8 extract_key(uint64 id) {
+    return static_cast<uint8>(id);
+  }
+  static Type extract_type(uint64 id) {
+    return static_cast<Type>(static_cast<uint8>(id >> 8));
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/UpdatesManager.cpp b/libs/tdlib/td/td/telegram/UpdatesManager.cpp
new file mode 100644
index 0000000000..43153d96a3
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/UpdatesManager.cpp
@@ -0,0 +1,1800 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/UpdatesManager.h"
+
+#include "td/telegram/telegram_api.hpp"
+
+#include "td/telegram/AnimationsManager.h"
+#include "td/telegram/AuthManager.h"
+#include "td/telegram/CallbackQueriesManager.h"
+#include "td/telegram/CallManager.h"
+#include "td/telegram/ChannelId.h"
+#include "td/telegram/ChatId.h"
+#include "td/telegram/ConfigManager.h"
+#include "td/telegram/ContactsManager.h"
+#include "td/telegram/DialogId.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/InlineQueriesManager.h"
+#include "td/telegram/Location.h"
+#include "td/telegram/MessageId.h"
+#include "td/telegram/MessagesManager.h"
+#include "td/telegram/net/DcOptions.h"
+#include "td/telegram/net/NetQuery.h"
+#include "td/telegram/Payments.h"
+#include "td/telegram/PrivacyManager.h"
+#include "td/telegram/SecretChatId.h"
+#include "td/telegram/SecretChatsManager.h"
+#include "td/telegram/StateManager.h"
+#include "td/telegram/StickersManager.h"
+#include "td/telegram/Td.h"
+#include "td/telegram/WebPagesManager.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Random.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+
+#include <limits>
+
+namespace td {
+
+class OnUpdate {
+  UpdatesManager *manager_;
+  tl_object_ptr<telegram_api::Update> &update_;
+  bool force_apply_;
+
+ public:
+  OnUpdate(UpdatesManager *manager, tl_object_ptr<telegram_api::Update> &update, bool force_apply)
+      : manager_(manager), update_(update), force_apply_(force_apply) {
+  }
+
+  template <class T>
+  void operator()(T &obj) const {
+    CHECK(&*update_ == &obj);
+    manager_->on_update(move_tl_object_as<T>(update_), force_apply_);
+  }
+};
+
+class GetUpdatesStateQuery : public Td::ResultHandler {
+ public:
+  void send() {
+    // TODO this call must be first after client is logged in, there must be no API calls before
+    // it succeeds
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::updates_getState())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::updates_getState>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto state = result_ptr.move_as_ok();
+    CHECK(state->get_id() == telegram_api::updates_state::ID);
+
+    td->updates_manager_->on_get_updates_state(std::move(state), "GetUpdatesStateQuery");
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.message() != CSlice("SESSION_REVOKED") && status.message() != CSlice("USER_DEACTIVATED")) {
+      LOG(ERROR) << "updates.getState error: " << status;
+    }
+    status.ignore();
+    td->updates_manager_->on_get_updates_state(nullptr, "GetUpdatesStateQuery");
+  }
+};
+
+class PingServerQuery : public Td::ResultHandler {
+ public:
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::updates_getState())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::updates_getState>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto state = result_ptr.move_as_ok();
+    CHECK(state->get_id() == telegram_api::updates_state::ID);
+    td->updates_manager_->on_server_pong(std::move(state));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    status.ignore();
+    td->updates_manager_->on_server_pong(nullptr);
+  }
+};
+
+class GetDifferenceQuery : public Td::ResultHandler {
+ public:
+  void send() {
+    int32 pts = td->updates_manager_->get_pts();
+    int32 date = td->updates_manager_->get_date();
+    int32 qts = td->updates_manager_->get_qts();
+    if (pts < 0) {
+      pts = 0;
+    }
+
+    LOG(INFO) << tag("pts", pts) << tag("qts", qts) << tag("date", date);
+
+    send_query(
+        G()->net_query_creator().create(create_storer(telegram_api::updates_getDifference(0, pts, 0, date, qts))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::updates_getDifference>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    td->updates_manager_->on_get_difference(result_ptr.move_as_ok());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    if (status.message() != CSlice("SESSION_REVOKED") && status.message() != CSlice("USER_DEACTIVATED")) {
+      LOG(ERROR) << "updates.getDifference error: " << status;
+    }
+    td->updates_manager_->on_get_difference(nullptr);
+    if (status.message() == CSlice("PERSISTENT_TIMESTAMP_INVALID")) {
+      td->updates_manager_->set_pts(std::numeric_limits<int32>::max(), "PERSISTENT_TIMESTAMP_INVALID")
+          .set_value(Unit());
+    }
+    status.ignore();
+  }
+};
+
+const double UpdatesManager::MAX_UNFILLED_GAP_TIME = 1.0;
+
+UpdatesManager::UpdatesManager(Td *td, ActorShared<> parent) : td_(td), parent_(std::move(parent)) {
+  pts_manager_.init(-1);
+}
+
+void UpdatesManager::tear_down() {
+  parent_.reset();
+}
+
+void UpdatesManager::fill_pts_gap(void *td) {
+  fill_gap(td, "pts");
+}
+
+void UpdatesManager::fill_seq_gap(void *td) {
+  fill_gap(td, "seq");
+}
+
+void UpdatesManager::fill_get_difference_gap(void *td) {
+  fill_gap(td, "getDifference");
+}
+
+void UpdatesManager::fill_gap(void *td, const char *source) {
+  CHECK(td != nullptr);
+  auto updates_manager = static_cast<Td *>(td)->updates_manager_.get();
+
+  LOG(WARNING) << "Filling gap in " << source << " by running getDifference. " << updates_manager->get_state();
+
+  updates_manager->get_difference("fill_gap");
+}
+
+string UpdatesManager::get_state() const {
+  char buff[1024];
+  StringBuilder sb({buff, sizeof(buff)});
+  sb << "UpdatesManager is in state ";
+  switch (state_.type) {
+    case State::Type::General:
+      sb << "General";
+      break;
+    case State::Type::RunningGetUpdatesState:
+      sb << "RunningGetUpdatesState";
+      break;
+    case State::Type::RunningGetDifference:
+      sb << "RunningGetDifference";
+      break;
+    case State::Type::ApplyingDifference:
+      sb << "ApplyingDifference";
+      break;
+    case State::Type::ApplyingDifferenceSlice:
+      sb << "ApplyingDifferenceSlice";
+      break;
+    case State::Type::ApplyingUpdates:
+      sb << "ApplyingUpdates";
+      break;
+    case State::Type::ApplyingSeqUpdates:
+      sb << "ApplyingSeqUpdates";
+      break;
+    default:
+      UNREACHABLE();
+  }
+  sb << " with pts = " << state_.pts << ", qts = " << state_.qts << " and date = " << state_.date;
+  CHECK(!sb.is_error());
+  return sb.as_cslice().str();
+}
+
+void UpdatesManager::set_state(State::Type type) {
+  state_.type = type;
+  state_.pts = get_pts();
+  state_.qts = qts_;
+  state_.date = date_;
+}
+
+void UpdatesManager::get_difference(const char *source) {
+  if (get_pts() == -1) {
+    init_state();
+    return;
+  }
+
+  if (!td_->auth_manager_->is_authorized()) {
+    return;
+  }
+
+  if (running_get_difference_) {
+    LOG(INFO) << "Skip running getDifference from " << source << " because it is already running";
+    return;
+  }
+  running_get_difference_ = true;
+
+  LOG(INFO) << "-----BEGIN GET DIFFERENCE----- from " << source;
+
+  before_get_difference();
+
+  td_->create_handler<GetDifferenceQuery>()->send();
+  last_get_difference_pts_ = get_pts();
+
+  set_state(State::Type::RunningGetDifference);
+}
+
+void UpdatesManager::before_get_difference() {
+  // may be called many times before after_get_difference is called
+  send_closure(G()->state_manager(), &StateManager::on_synchronized, false);
+
+  td_->messages_manager_->before_get_difference();
+  send_closure(td_->secret_chats_manager_, &SecretChatsManager::before_get_difference, get_qts());
+}
+
+Promise<> UpdatesManager::add_pts(int32 pts) {
+  auto id = pts_manager_.add_pts(pts);
+  return PromiseCreator::event(self_closure(this, &UpdatesManager::on_pts_ack, id));
+}
+
+void UpdatesManager::on_pts_ack(PtsManager::PtsId ack_token) {
+  auto old_pts = pts_manager_.db_pts();
+  auto new_pts = pts_manager_.finish(ack_token);
+  if (old_pts != new_pts) {
+    save_pts(new_pts);
+  }
+}
+
+void UpdatesManager::save_pts(int32 pts) {
+  if (pts == std::numeric_limits<int32>::max()) {
+    G()->td_db()->get_binlog_pmc()->erase("updates.pts");
+  } else {
+    G()->td_db()->get_binlog_pmc()->set("updates.pts", to_string(pts));
+  }
+}
+
+Promise<> UpdatesManager::set_pts(int32 pts, const char *source) {
+  if (pts == std::numeric_limits<int32>::max()) {
+    LOG(WARNING) << "Update pts from " << get_pts() << " to -1 from " << source;
+    G()->td_db()->get_binlog_pmc()->erase("updates.pts");
+    auto result = add_pts(std::numeric_limits<int32>::max());
+    init_state();
+    return result;
+  }
+  Promise<> result;
+  if (pts > get_pts() || (0 < pts && pts < get_pts() - 999999)) {  // pts can only go up or drop cardinally
+    if (pts < get_pts() - 999999) {
+      LOG(WARNING) << "Pts decreases from " << get_pts() << " to " << pts << " from " << source << ". " << get_state();
+    } else {
+      LOG(INFO) << "Update pts from " << get_pts() << " to " << pts << " from " << source;
+    }
+
+    result = add_pts(pts);
+    if (last_get_difference_pts_ + FORCED_GET_DIFFERENCE_PTS_DIFF < get_pts()) {
+      last_get_difference_pts_ = get_pts();
+      schedule_get_difference("set_pts");
+    }
+  } else if (pts < get_pts()) {
+    LOG(ERROR) << "Receive wrong pts = " << pts << " from " << source << ". Current pts = " << get_pts() << ". "
+               << get_state();
+  }
+  return result;
+}
+
+void UpdatesManager::set_qts(int32 qts) {
+  if (qts > qts_) {
+    LOG(INFO) << "Update qts to " << qts;
+
+    qts_ = qts;
+    G()->td_db()->get_binlog_pmc()->set("updates.qts", to_string(qts));
+  } else if (qts < qts_) {
+    LOG(ERROR) << "Receive wrong qts = " << qts << ". Current qts = " << qts_ << ". " << get_state();
+  }
+}
+
+void UpdatesManager::set_date(int32 date, bool from_update, string date_source) {
+  if (date > date_) {
+    LOG(INFO) << "Update date to " << date;
+    if (from_update && false) {  // date in updates is decreased by the server
+      date--;
+
+      if (date == date_) {
+        return;
+      }
+    }
+    auto now = G()->unix_time();
+    if (date_ > now + 1) {
+      LOG(ERROR) << "Receive wrong by " << (date_ - now) << " date = " << date_ << " from " << date_source
+                 << ". Now = " << now;
+      date_ = now;
+      if (date_ <= date) {
+        return;
+      }
+    }
+
+    date_ = date;
+    date_source_ = std::move(date_source);
+    G()->td_db()->get_binlog_pmc()->set("updates.date", to_string(date));
+  } else if (date < date_) {
+    if (from_update) {
+      date++;
+
+      if (date == date_) {
+        return;
+      }
+    }
+    LOG(ERROR) << "Receive wrong by " << (date_ - date) << " date = " << date << " from " << date_source
+               << ". Current date = " << date_ << " from " << date_source_ << ". " << get_state();
+  }
+}
+
+bool UpdatesManager::is_acceptable_message_entities(
+    const vector<tl_object_ptr<telegram_api::MessageEntity>> &message_entities) const {
+  for (auto &entity : message_entities) {
+    if (entity->get_id() == telegram_api::messageEntityMentionName::ID) {
+      auto entity_mention_name = static_cast<const telegram_api::messageEntityMentionName *>(entity.get());
+      UserId user_id(entity_mention_name->user_id_);
+      if (!td_->contacts_manager_->have_user(user_id) || !td_->contacts_manager_->have_input_user(user_id)) {
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
+bool UpdatesManager::is_acceptable_message(const telegram_api::Message *message_ptr) const {
+  CHECK(message_ptr != nullptr);
+  int32 constructor_id = message_ptr->get_id();
+
+  bool is_channel_post = false;
+  DialogId dialog_id;
+  UserId sender_user_id;
+
+  switch (constructor_id) {
+    case telegram_api::messageEmpty::ID:
+      return true;
+    case telegram_api::message::ID: {
+      auto message = static_cast<const telegram_api::message *>(message_ptr);
+
+      is_channel_post = (message->flags_ & MessagesManager::MESSAGE_FLAG_IS_POST) != 0;
+      dialog_id = DialogId(message->to_id_);
+      if (message->flags_ & MessagesManager::MESSAGE_FLAG_HAS_FROM_ID) {
+        sender_user_id = UserId(message->from_id_);
+      }
+
+      if (message->flags_ & MessagesManager::MESSAGE_FLAG_IS_FORWARDED) {
+        CHECK(message->fwd_from_ != nullptr);
+        auto flags = message->fwd_from_->flags_;
+        bool from_post = (flags & MessagesManager::MESSAGE_FORWARD_HEADER_FLAG_HAS_CHANNEL_ID) != 0;
+        if (from_post && !td_->contacts_manager_->have_channel(ChannelId(message->fwd_from_->channel_id_))) {
+          return false;
+        }
+        if (flags & MessagesManager::MESSAGE_FORWARD_HEADER_FLAG_HAS_AUTHOR_ID) {
+          UserId user_id(message->fwd_from_->from_id_);
+          if (from_post && !td_->contacts_manager_->have_min_user(user_id)) {
+            return false;
+          }
+          if (!from_post && !td_->contacts_manager_->have_user(user_id)) {
+            return false;
+          }
+        }
+      } else {
+        CHECK(message->fwd_from_ == nullptr);
+      }
+
+      if ((message->flags_ & MessagesManager::MESSAGE_FLAG_IS_SENT_VIA_BOT) &&
+          !td_->contacts_manager_->have_user(UserId(message->via_bot_id_))) {
+        return false;
+      }
+
+      if (!is_acceptable_message_entities(message->entities_)) {
+        return false;
+      }
+
+      if (message->flags_ & MessagesManager::MESSAGE_FLAG_HAS_MEDIA) {
+        CHECK(message->media_ != nullptr);
+        auto media_id = message->media_->get_id();
+        if (media_id == telegram_api::messageMediaContact::ID) {
+          auto message_media_contact = static_cast<const telegram_api::messageMediaContact *>(message->media_.get());
+          UserId user_id(message_media_contact->user_id_);
+          if (user_id != UserId() && !td_->contacts_manager_->have_user(user_id)) {
+            return false;
+          }
+        }
+        /*
+        if (media_id == telegram_api::messageMediaWebPage::ID) {
+          auto message_media_web_page = static_cast<const telegram_api::messageMediaWebPage *>(message->media_.get());
+          if (message_media_web_page->webpage_->get_id() == telegram_api::webPage::ID) {
+            auto web_page = static_cast<const telegram_api::webPage *>(message_media_web_page->webpage_.get());
+            if (web_page->cached_page_ != nullptr) {
+              const vector<tl_object_ptr<telegram_api::PageBlock>> *page_blocks = nullptr;
+              downcast_call(*web_page->cached_page_, [&page_blocks](auto &page) { page_blocks = &page.blocks_; });
+              CHECK(page_blocks != nullptr);
+              for (auto &page_block : *page_blocks) {
+                if (page_block->get_id() == telegram_api::pageBlockChannel::ID) {
+                  auto page_block_channel = static_cast<const telegram_api::pageBlockChannel *>(page_block.get());
+                  auto channel_id = ContactsManager::get_channel_id(page_block_channel->channel_);
+                  if (channel_id.is_valid()) {
+                    if (!td_->contacts_manager_->have_channel(channel_id)) {
+                      return false;
+                    }
+                  } else {
+                    LOG(ERROR) << "Receive wrong channel " << to_string(page_block_channel->channel_);
+                  }
+                }
+              }
+            }
+          }
+        }
+        */
+      } else {
+        CHECK(message->media_ == nullptr);
+      }
+
+      break;
+    }
+    case telegram_api::messageService::ID: {
+      auto message = static_cast<const telegram_api::messageService *>(message_ptr);
+
+      is_channel_post = (message->flags_ & MessagesManager::MESSAGE_FLAG_IS_POST) != 0;
+      dialog_id = DialogId(message->to_id_);
+      if (message->flags_ & MessagesManager::MESSAGE_FLAG_HAS_FROM_ID) {
+        sender_user_id = UserId(message->from_id_);
+      }
+
+      const telegram_api::MessageAction *action = message->action_.get();
+      CHECK(action != nullptr);
+
+      switch (action->get_id()) {
+        case telegram_api::messageActionEmpty::ID:
+        case telegram_api::messageActionChatEditTitle::ID:
+        case telegram_api::messageActionChatEditPhoto::ID:
+        case telegram_api::messageActionChatDeletePhoto::ID:
+        case telegram_api::messageActionCustomAction::ID:
+        case telegram_api::messageActionBotAllowed::ID:
+        case telegram_api::messageActionHistoryClear::ID:
+        case telegram_api::messageActionChannelCreate::ID:
+        case telegram_api::messageActionPinMessage::ID:
+        case telegram_api::messageActionGameScore::ID:
+        case telegram_api::messageActionPhoneCall::ID:
+        case telegram_api::messageActionPaymentSent::ID:
+        case telegram_api::messageActionPaymentSentMe::ID:
+        case telegram_api::messageActionScreenshotTaken::ID:
+          break;
+        case telegram_api::messageActionChatCreate::ID: {
+          auto chat_create = static_cast<const telegram_api::messageActionChatCreate *>(action);
+          for (auto &user : chat_create->users_) {
+            if (!td_->contacts_manager_->have_user(UserId(user))) {
+              return false;
+            }
+          }
+          break;
+        }
+        case telegram_api::messageActionChatAddUser::ID: {
+          auto chat_add_user = static_cast<const telegram_api::messageActionChatAddUser *>(action);
+          for (auto &user : chat_add_user->users_) {
+            if (!td_->contacts_manager_->have_user(UserId(user))) {
+              return false;
+            }
+          }
+          break;
+        }
+        case telegram_api::messageActionChatJoinedByLink::ID: {
+          auto chat_joined_by_link = static_cast<const telegram_api::messageActionChatJoinedByLink *>(action);
+          if (!td_->contacts_manager_->have_user(UserId(chat_joined_by_link->inviter_id_))) {
+            return false;
+          }
+          break;
+        }
+        case telegram_api::messageActionChatDeleteUser::ID: {
+          auto chat_delete_user = static_cast<const telegram_api::messageActionChatDeleteUser *>(action);
+          if (!td_->contacts_manager_->have_user(UserId(chat_delete_user->user_id_))) {
+            return false;
+          }
+          break;
+        }
+        case telegram_api::messageActionChatMigrateTo::ID: {
+          auto chat_migrate_to = static_cast<const telegram_api::messageActionChatMigrateTo *>(action);
+          if (!td_->contacts_manager_->have_channel(ChannelId(chat_migrate_to->channel_id_))) {
+            return false;
+          }
+          break;
+        }
+        case telegram_api::messageActionChannelMigrateFrom::ID: {
+          auto channel_migrate_from = static_cast<const telegram_api::messageActionChannelMigrateFrom *>(action);
+          if (!td_->contacts_manager_->have_chat(ChatId(channel_migrate_from->chat_id_))) {
+            return false;
+          }
+          break;
+        }
+        default:
+          UNREACHABLE();
+          return false;
+      }
+      break;
+    }
+    default:
+      UNREACHABLE();
+      return false;
+  }
+
+  switch (dialog_id.get_type()) {
+    case DialogType::None:
+      LOG(ERROR) << "Receive message in the invalid " << dialog_id;
+      return false;
+    case DialogType::User: {
+      if (!td_->contacts_manager_->have_user(dialog_id.get_user_id())) {
+        return false;
+      }
+      break;
+    }
+    case DialogType::Chat: {
+      if (!td_->contacts_manager_->have_chat(dialog_id.get_chat_id())) {
+        return false;
+      }
+      break;
+    }
+    case DialogType::Channel: {
+      if (!td_->contacts_manager_->have_channel(dialog_id.get_channel_id())) {
+        return false;
+      }
+      break;
+    }
+    case DialogType::SecretChat:
+    default:
+      UNREACHABLE();
+      return false;
+  }
+
+  if (sender_user_id != UserId()) {
+    if (is_channel_post && !td_->contacts_manager_->have_min_user(sender_user_id)) {
+      return false;
+    }
+    if (!is_channel_post && !td_->contacts_manager_->have_user(sender_user_id)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool UpdatesManager::is_acceptable_update(const telegram_api::Update *update) const {
+  if (update == nullptr) {
+    return true;
+  }
+  int32 id = update->get_id();
+  const telegram_api::Message *message = nullptr;
+  if (id == telegram_api::updateNewMessage::ID) {
+    message = static_cast<const telegram_api::updateNewMessage *>(update)->message_.get();
+  }
+  if (id == telegram_api::updateNewChannelMessage::ID) {
+    message = static_cast<const telegram_api::updateNewChannelMessage *>(update)->message_.get();
+  }
+  if (id == telegram_api::updateEditMessage::ID) {
+    message = static_cast<const telegram_api::updateEditMessage *>(update)->message_.get();
+  }
+  if (id == telegram_api::updateEditChannelMessage::ID) {
+    message = static_cast<const telegram_api::updateEditChannelMessage *>(update)->message_.get();
+  }
+  if (message != nullptr) {
+    return is_acceptable_message(message);
+  }
+
+  if (id == telegram_api::updateDraftMessage::ID) {
+    auto update_draft_message = static_cast<const telegram_api::updateDraftMessage *>(update);
+    CHECK(update_draft_message->draft_ != nullptr);
+    if (update_draft_message->draft_->get_id() == telegram_api::draftMessage::ID) {
+      auto draft_message = static_cast<const telegram_api::draftMessage *>(update_draft_message->draft_.get());
+      return is_acceptable_message_entities(draft_message->entities_);
+    }
+  }
+
+  return true;
+}
+
+void UpdatesManager::on_get_updates(tl_object_ptr<telegram_api::Updates> &&updates_ptr) {
+  CHECK(updates_ptr != nullptr);
+  auto updates_type = updates_ptr->get_id();
+  if (updates_type != telegram_api::updateShort::ID) {
+    LOG(INFO) << "Receive " << to_string(updates_ptr);
+  }
+  if (!td_->auth_manager_->is_authorized()) {
+    LOG(INFO) << "Ignore updates received before authorization or after logout";
+    return;
+  }
+
+  switch (updates_ptr->get_id()) {
+    case telegram_api::updatesTooLong::ID:
+      get_difference("updatesTooLong");
+      break;
+    case telegram_api::updateShortMessage::ID: {
+      auto update = move_tl_object_as<telegram_api::updateShortMessage>(updates_ptr);
+      if (update->flags_ & MessagesManager::MESSAGE_FLAG_HAS_REPLY_MARKUP) {
+        LOG(ERROR) << "Receive updateShortMessage with reply_markup";
+        update->flags_ ^= MessagesManager::MESSAGE_FLAG_HAS_REPLY_MARKUP;
+      }
+      if (update->flags_ & MessagesManager::MESSAGE_FLAG_HAS_MEDIA) {
+        LOG(ERROR) << "Receive updateShortMessage with media";
+        update->flags_ ^= MessagesManager::MESSAGE_FLAG_HAS_MEDIA;
+      }
+
+      auto from_id = update->flags_ & MessagesManager::MESSAGE_FLAG_IS_OUT
+                         ? td_->contacts_manager_->get_my_id("on_get_updates").get()
+                         : update->user_id_;
+
+      update->flags_ |= MessagesManager::MESSAGE_FLAG_HAS_FROM_ID;
+      on_pending_update(
+          make_tl_object<telegram_api::updateNewMessage>(
+              make_tl_object<telegram_api::message>(
+                  update->flags_, false /*ignored*/, false /*ignored*/, false /*ignored*/, false /*ignored*/,
+                  false /*ignored*/, update->id_, from_id, make_tl_object<telegram_api::peerUser>(update->user_id_),
+                  std::move(update->fwd_from_), update->via_bot_id_, update->reply_to_msg_id_, update->date_,
+                  update->message_, nullptr, nullptr, std::move(update->entities_), 0, 0, "", 0),
+              update->pts_, update->pts_count_),
+          0, "telegram_api::updatesShortMessage");
+      break;
+    }
+    case telegram_api::updateShortChatMessage::ID: {
+      auto update = move_tl_object_as<telegram_api::updateShortChatMessage>(updates_ptr);
+      if (update->flags_ & MessagesManager::MESSAGE_FLAG_HAS_REPLY_MARKUP) {
+        LOG(ERROR) << "Receive updateShortChatMessage with reply_markup";
+        update->flags_ ^= MessagesManager::MESSAGE_FLAG_HAS_REPLY_MARKUP;
+      }
+      if (update->flags_ & MessagesManager::MESSAGE_FLAG_HAS_MEDIA) {
+        LOG(ERROR) << "Receive updateShortChatMessage with media";
+        update->flags_ ^= MessagesManager::MESSAGE_FLAG_HAS_MEDIA;
+      }
+
+      update->flags_ |= MessagesManager::MESSAGE_FLAG_HAS_FROM_ID;
+      on_pending_update(make_tl_object<telegram_api::updateNewMessage>(
+                            make_tl_object<telegram_api::message>(
+                                update->flags_, false /*ignored*/, false /*ignored*/, false /*ignored*/,
+                                false /*ignored*/, false /*ignored*/, update->id_, update->from_id_,
+                                make_tl_object<telegram_api::peerChat>(update->chat_id_), std::move(update->fwd_from_),
+                                update->via_bot_id_, update->reply_to_msg_id_, update->date_, update->message_, nullptr,
+                                nullptr, std::move(update->entities_), 0, 0, "", 0),
+                            update->pts_, update->pts_count_),
+                        0, "telegram_api::updatesShortChatMessage");
+      break;
+    }
+    case telegram_api::updateShort::ID: {
+      auto update = move_tl_object_as<telegram_api::updateShort>(updates_ptr);
+      LOG(DEBUG) << "Receive " << to_string(update);
+      if (!is_acceptable_update(update->update_.get())) {
+        LOG(ERROR) << "Receive unacceptable short update: " << td::oneline(to_string(update));
+        return get_difference("unacceptable short update");
+      }
+
+      if (!downcast_call(*update->update_, OnUpdate(this, update->update_, false))) {
+        LOG(ERROR) << "Can't call on some update";
+      }
+      break;
+    }
+    case telegram_api::updatesCombined::ID: {
+      auto updates = move_tl_object_as<telegram_api::updatesCombined>(updates_ptr);
+      td_->contacts_manager_->on_get_users(std::move(updates->users_));
+      td_->contacts_manager_->on_get_chats(std::move(updates->chats_));
+      on_pending_updates(std::move(updates->updates_), updates->seq_start_, updates->seq_, updates->date_,
+                         "telegram_api::updatesCombined");
+      break;
+    }
+    case telegram_api::updates::ID: {
+      auto updates = move_tl_object_as<telegram_api::updates>(updates_ptr);
+      td_->contacts_manager_->on_get_users(std::move(updates->users_));
+      td_->contacts_manager_->on_get_chats(std::move(updates->chats_));
+      on_pending_updates(std::move(updates->updates_), updates->seq_, updates->seq_, updates->date_,
+                         "telegram_api::updates");
+      break;
+    }
+    case telegram_api::updateShortSentMessage::ID:
+      LOG(ERROR) << "Receive " << oneline(to_string(updates_ptr));
+      get_difference("updateShortSentMessage");
+      break;
+    default:
+      UNREACHABLE();
+  }
+}
+
+void UpdatesManager::on_failed_get_difference() {
+  schedule_get_difference("on_failed_get_difference");
+}
+
+void UpdatesManager::schedule_get_difference(const char *source) {
+  LOG(INFO) << "Schedule getDifference from " << source;
+  if (!retry_timeout_.has_timeout()) {
+    retry_timeout_.set_callback(std::move(fill_get_difference_gap));
+    retry_timeout_.set_callback_data(static_cast<void *>(td_));
+    retry_timeout_.set_timeout_in(retry_time_);
+    retry_time_ *= 2;
+    if (retry_time_ > 60) {
+      retry_time_ = Random::fast(60, 80);
+    }
+  }
+}
+
+void UpdatesManager::on_get_updates_state(tl_object_ptr<telegram_api::updates_state> &&state, const char *source) {
+  if (state == nullptr) {
+    running_get_difference_ = false;
+    on_failed_get_difference();
+    return;
+  }
+  LOG(INFO) << "Receive " << oneline(to_string(state)) << " from " << source;
+  // TODO use state->unread_count;
+
+  if (get_pts() == std::numeric_limits<int32>::max()) {
+    LOG(WARNING) << "Restore pts to " << state->pts_;
+    // restoring right pts
+    pts_manager_.init(state->pts_);
+    last_get_difference_pts_ = get_pts();
+  } else {
+    string full_source = "on_get_updates_state " + oneline(to_string(state)) + " from " + source;
+    set_pts(state->pts_, full_source.c_str()).set_value(Unit());
+    set_date(state->date_, false, std::move(full_source));
+    // set_qts(state->qts_);
+
+    seq_ = state->seq_;
+  }
+
+  if (running_get_difference_) {  // called from getUpdatesState
+    running_get_difference_ = false;
+    after_get_difference();
+  }
+}
+
+std::unordered_set<int64> UpdatesManager::get_sent_messages_random_ids(const telegram_api::Updates *updates_ptr) {
+  std::unordered_set<int64> random_ids;
+  const vector<tl_object_ptr<telegram_api::Update>> *updates;
+  switch (updates_ptr->get_id()) {
+    case telegram_api::updatesTooLong::ID:
+    case telegram_api::updateShortMessage::ID:
+    case telegram_api::updateShortChatMessage::ID:
+    case telegram_api::updateShort::ID:
+    case telegram_api::updateShortSentMessage::ID:
+      LOG(ERROR) << "Receive " << oneline(to_string(*updates_ptr)) << " instead of updates";
+      return random_ids;
+    case telegram_api::updatesCombined::ID: {
+      updates = &static_cast<const telegram_api::updatesCombined *>(updates_ptr)->updates_;
+      break;
+    }
+    case telegram_api::updates::ID: {
+      updates = &static_cast<const telegram_api::updates *>(updates_ptr)->updates_;
+      break;
+    }
+    default:
+      UNREACHABLE();
+      return random_ids;
+  }
+  for (auto &update : *updates) {
+    if (update->get_id() == telegram_api::updateMessageID::ID) {
+      int64 random_id = static_cast<const telegram_api::updateMessageID *>(update.get())->random_id_;
+      if (!random_ids.insert(random_id).second) {
+        LOG(ERROR) << "Receive twice updateMessageID for " << random_id;
+      }
+    }
+  }
+  return random_ids;
+}
+
+vector<const tl_object_ptr<telegram_api::Message> *> UpdatesManager::get_new_messages(
+    const telegram_api::Updates *updates_ptr) {
+  vector<const tl_object_ptr<telegram_api::Message> *> messages;
+  const vector<tl_object_ptr<telegram_api::Update>> *updates;
+  switch (updates_ptr->get_id()) {
+    case telegram_api::updatesTooLong::ID:
+    case telegram_api::updateShortMessage::ID:
+    case telegram_api::updateShortChatMessage::ID:
+    case telegram_api::updateShort::ID:
+    case telegram_api::updateShortSentMessage::ID:
+      LOG(ERROR) << "Receive " << oneline(to_string(*updates_ptr)) << " instead of updates";
+      return messages;
+    case telegram_api::updatesCombined::ID: {
+      updates = &static_cast<const telegram_api::updatesCombined *>(updates_ptr)->updates_;
+      break;
+    }
+    case telegram_api::updates::ID: {
+      updates = &static_cast<const telegram_api::updates *>(updates_ptr)->updates_;
+      break;
+    }
+    default:
+      UNREACHABLE();
+      return messages;
+  }
+  for (auto &update : *updates) {
+    auto constructor_id = update->get_id();
+    if (constructor_id == telegram_api::updateNewMessage::ID) {
+      messages.emplace_back(&static_cast<const telegram_api::updateNewMessage *>(update.get())->message_);
+    } else if (constructor_id == telegram_api::updateNewChannelMessage::ID) {
+      messages.emplace_back(&static_cast<const telegram_api::updateNewChannelMessage *>(update.get())->message_);
+    }
+  }
+  return messages;
+}
+
+vector<DialogId> UpdatesManager::get_chats(const telegram_api::Updates *updates_ptr) {
+  const vector<tl_object_ptr<telegram_api::Chat>> *chats = nullptr;
+  switch (updates_ptr->get_id()) {
+    case telegram_api::updatesTooLong::ID:
+    case telegram_api::updateShortMessage::ID:
+    case telegram_api::updateShortChatMessage::ID:
+    case telegram_api::updateShort::ID:
+    case telegram_api::updateShortSentMessage::ID:
+      LOG(ERROR) << "Receive " << oneline(to_string(*updates_ptr)) << " instead of updates";
+      break;
+    case telegram_api::updatesCombined::ID: {
+      chats = &static_cast<const telegram_api::updatesCombined *>(updates_ptr)->chats_;
+      break;
+    }
+    case telegram_api::updates::ID: {
+      chats = &static_cast<const telegram_api::updates *>(updates_ptr)->chats_;
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+
+  if (chats == nullptr) {
+    return {};
+  }
+
+  vector<DialogId> dialog_ids;
+  dialog_ids.reserve(chats->size());
+  for (const auto &chat : *chats) {
+    auto chat_id = ContactsManager::get_chat_id(chat);
+    if (chat_id.is_valid()) {
+      dialog_ids.push_back(DialogId(chat_id));
+      continue;
+    }
+
+    auto channel_id = ContactsManager::get_channel_id(chat);
+    if (channel_id.is_valid()) {
+      dialog_ids.push_back(DialogId(channel_id));
+      continue;
+    }
+
+    LOG(ERROR) << "Can't find id of " << oneline(to_string(chat));
+  }
+  return dialog_ids;
+}
+
+void UpdatesManager::init_state() {
+  if (!td_->auth_manager_->is_authorized()) {
+    return;
+  }
+
+  auto pmc = G()->td_db()->get_binlog_pmc();
+  string pts_str = pmc->get("updates.pts");
+  if (pts_str.empty()) {
+    if (!running_get_difference_) {
+      running_get_difference_ = true;
+      send_closure(G()->state_manager(), &StateManager::on_synchronized, false);
+      td_->create_handler<GetUpdatesStateQuery>()->send();
+
+      set_state(State::Type::RunningGetUpdatesState);
+    }
+    return;
+  }
+  pts_manager_.init(to_integer<int32>(pts_str));
+  last_get_difference_pts_ = get_pts();
+  qts_ = to_integer<int32>(pmc->get("updates.qts"));
+  date_ = to_integer<int32>(pmc->get("updates.date"));
+  date_source_ = "database";
+  LOG(DEBUG) << "Init: " << get_pts() << " " << qts_ << " " << date_;
+  send_closure(td_->secret_chats_manager_, &SecretChatsManager::init_qts, qts_);
+
+  get_difference("init_state");
+}
+
+void UpdatesManager::ping_server() {
+  td_->create_handler<PingServerQuery>()->send();
+}
+
+void UpdatesManager::on_server_pong(tl_object_ptr<telegram_api::updates_state> &&state) {
+  LOG(INFO) << "Receive " << oneline(to_string(state));
+  if (state == nullptr || state->pts_ > get_pts() || state->seq_ > seq_) {
+    get_difference("on server pong");
+  }
+}
+
+void UpdatesManager::process_get_difference_updates(
+    vector<tl_object_ptr<telegram_api::Message>> &&new_messages,
+    vector<tl_object_ptr<telegram_api::EncryptedMessage>> &&new_encrypted_messages, int32 qts,
+    vector<tl_object_ptr<telegram_api::Update>> &&other_updates) {
+  LOG(INFO) << "In get difference receive " << new_messages.size() << " messages, " << new_encrypted_messages.size()
+            << " encrypted messages and " << other_updates.size() << " other updates";
+  for (auto &update : other_updates) {
+    auto constructor_id = update->get_id();
+    if (constructor_id == telegram_api::updateMessageID::ID) {
+      on_update(move_tl_object_as<telegram_api::updateMessageID>(update), true);
+      CHECK(!running_get_difference_);
+    }
+
+    if (constructor_id == telegram_api::updateEncryption::ID) {
+      on_update(move_tl_object_as<telegram_api::updateEncryption>(update), true);
+      CHECK(!running_get_difference_);
+    }
+
+    /*
+        // TODO can't apply it here, because dialog may not be created yet
+        // process updateReadHistoryInbox before new messages
+        if (constructor_id == telegram_api::updateReadHistoryInbox::ID) {
+          on_update(move_tl_object_as<telegram_api::updateReadHistoryInbox>(update), true);
+          CHECK(!running_get_difference_);
+        }
+    */
+  }
+
+  for (auto &message : new_messages) {
+    // channel messages must not be received in this vector
+    td_->messages_manager_->on_get_message(std::move(message), true, false, true, true, "get difference");
+    CHECK(!running_get_difference_);
+  }
+
+  for (auto &encrypted_message : new_encrypted_messages) {
+    on_update(make_tl_object<telegram_api::updateNewEncryptedMessage>(std::move(encrypted_message), 0), true);
+  }
+  send_closure(td_->secret_chats_manager_, &SecretChatsManager::update_qts, qts);
+
+  process_updates(std::move(other_updates), true);
+}
+
+void UpdatesManager::on_get_difference(tl_object_ptr<telegram_api::updates_Difference> &&difference_ptr) {
+  LOG(INFO) << "----- END  GET DIFFERENCE-----";
+  running_get_difference_ = false;
+
+  if (difference_ptr == nullptr) {
+    on_failed_get_difference();
+    return;
+  }
+
+  LOG(DEBUG) << "Result of get difference: " << to_string(difference_ptr);
+
+  switch (difference_ptr->get_id()) {
+    case telegram_api::updates_differenceEmpty::ID: {
+      auto difference = move_tl_object_as<telegram_api::updates_differenceEmpty>(difference_ptr);
+      set_date(difference->date_, false, "on_get_difference_empty");
+      seq_ = difference->seq_;
+      break;
+    }
+    case telegram_api::updates_difference::ID: {
+      auto difference = move_tl_object_as<telegram_api::updates_difference>(difference_ptr);
+      td_->contacts_manager_->on_get_users(std::move(difference->users_));
+      td_->contacts_manager_->on_get_chats(std::move(difference->chats_));
+
+      set_state(State::Type::ApplyingDifference);
+
+      process_get_difference_updates(std::move(difference->new_messages_),
+                                     std::move(difference->new_encrypted_messages_), difference->state_->qts_,
+                                     std::move(difference->other_updates_));
+      if (running_get_difference_) {
+        LOG(ERROR) << "Get difference has run while processing get difference updates";
+        break;
+      }
+
+      on_get_updates_state(std::move(difference->state_), "get difference");
+      break;
+    }
+    case telegram_api::updates_differenceSlice::ID: {
+      auto difference = move_tl_object_as<telegram_api::updates_differenceSlice>(difference_ptr);
+      td_->contacts_manager_->on_get_users(std::move(difference->users_));
+      td_->contacts_manager_->on_get_chats(std::move(difference->chats_));
+
+      set_state(State::Type::ApplyingDifferenceSlice);
+
+      process_get_difference_updates(std::move(difference->new_messages_),
+                                     std::move(difference->new_encrypted_messages_),
+                                     difference->intermediate_state_->qts_, std::move(difference->other_updates_));
+      if (running_get_difference_) {
+        LOG(ERROR) << "Get difference has run while processing get difference updates";
+        break;
+      }
+
+      on_get_updates_state(std::move(difference->intermediate_state_), "get difference slice");
+      get_difference("on updates_differenceSlice");
+      break;
+    }
+    case telegram_api::updates_differenceTooLong::ID: {
+      LOG(ERROR) << "Receive differenceTooLong";
+      // TODO
+      auto difference = move_tl_object_as<telegram_api::updates_differenceTooLong>(difference_ptr);
+      set_pts(difference->pts_, "differenceTooLong").set_value(Unit());
+      get_difference("on updates_differenceTooLong");
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+
+  if (!running_get_difference_) {
+    after_get_difference();
+  }
+}
+
+void UpdatesManager::after_get_difference() {
+  CHECK(!running_get_difference_);
+  send_closure(td_->secret_chats_manager_, &SecretChatsManager::after_get_difference);
+  auto saved_state = state_;
+
+  retry_timeout_.cancel_timeout();
+  retry_time_ = 1;
+
+  process_pending_seq_updates();  // cancels seq_gap_timeout_, may apply some updates coming before getDifference, but
+                                  // not returned in getDifference
+  if (running_get_difference_) {
+    return;
+  }
+
+  if (postponed_updates_.size()) {
+    LOG(INFO) << "Begin to apply postponed updates";
+    while (!postponed_updates_.empty()) {
+      auto it = postponed_updates_.begin();
+      auto updates = std::move(it->second.updates);
+      auto updates_seq_begin = it->second.seq_begin;
+      auto updates_seq_end = it->second.seq_end;
+      // ignore it->second.date, because it may be too old
+      postponed_updates_.erase(it);
+      on_pending_updates(std::move(updates), updates_seq_begin, updates_seq_end, 0, "postponed updates");
+      if (running_get_difference_) {
+        LOG(INFO) << "Finish to apply postponed updates because forced to run getDifference";
+        return;
+      }
+    }
+    LOG(INFO) << "Finish to apply postponed updates";
+  }
+
+  state_ = saved_state;
+
+  td_->inline_queries_manager_->after_get_difference();
+  td_->messages_manager_->after_get_difference();
+  send_closure(G()->state_manager(), &StateManager::on_synchronized, true);
+
+  set_state(State::Type::General);
+}
+
+void UpdatesManager::on_pending_updates(vector<tl_object_ptr<telegram_api::Update>> &&updates, int32 seq_begin,
+                                        int32 seq_end, int32 date, const char *source) {
+  if (get_pts() == -1) {
+    init_state();
+  }
+
+  if (!td_->auth_manager_->is_authorized()) {
+    LOG(INFO) << "Ignore updates received before authorization or after logout";
+    return;
+  }
+
+  //  for (auto &update : updates) {
+  //    LOG(WARNING) << "Receive update " << to_string(update.get());
+  //  }
+
+  if (seq_begin < 0 || seq_end < 0 || date < 0 || seq_end < seq_begin) {
+    LOG(ERROR) << "Wrong updates parameters seq_begin = " << seq_begin << ", seq_end = " << seq_end
+               << ", date = " << date << " from " << source;
+    get_difference("on wrong updates in on_pending_updates");
+    return;
+  }
+
+  if (running_get_difference_) {
+    LOG(INFO) << "Postpone " << updates.size() << " updates [" << seq_begin << ", " << seq_end
+              << "] with date = " << date << " from " << source;
+    postponed_updates_.emplace(seq_begin, PendingUpdates(seq_begin, seq_end, date, std::move(updates)));
+    return;
+  }
+
+  // TODO typings must be processed before NewMessage
+
+  size_t processed_updates = 0;
+
+  for (auto &update : updates) {
+    if (!is_acceptable_update(update.get())) {
+      CHECK(update != nullptr);
+      int32 id = update->get_id();
+      const tl_object_ptr<telegram_api::Message> *message_ptr = nullptr;
+      int32 pts = 0;
+      if (id == telegram_api::updateNewChannelMessage::ID) {
+        auto update_new_channel_message = static_cast<const telegram_api::updateNewChannelMessage *>(update.get());
+        message_ptr = &update_new_channel_message->message_;
+        pts = update_new_channel_message->pts_;
+      }
+      if (id == telegram_api::updateEditChannelMessage::ID) {
+        auto update_edit_channel_message = static_cast<const telegram_api::updateEditChannelMessage *>(update.get());
+        message_ptr = &update_edit_channel_message->message_;
+        pts = update_edit_channel_message->pts_;
+      }
+      if (message_ptr != nullptr) {
+        auto dialog_id = td_->messages_manager_->get_message_dialog_id(*message_ptr);
+        if (dialog_id.get_type() == DialogType::Channel) {
+          // for channels we can replace unacceptable update with updateChannelTooLong
+          update = telegram_api::make_object<telegram_api::updateChannelTooLong>(
+              telegram_api::updateChannelTooLong::PTS_MASK, dialog_id.get_channel_id().get(), pts);
+          continue;
+        } else {
+          LOG(ERROR) << "Update is not from a channel: " << to_string(update);
+        }
+      }
+
+      return get_difference("on unacceptable updates in on_pending_updates");
+    }
+  }
+
+  set_state(State::Type::ApplyingUpdates);
+
+  for (auto &update : updates) {
+    if (update != nullptr) {
+      LOG(INFO) << "Receive from " << source << " pending " << to_string(update);
+      int32 id = update->get_id();
+      if (id == telegram_api::updateMessageID::ID) {
+        LOG(INFO) << "Receive from " << source << " " << to_string(update);
+        auto sent_message_update = move_tl_object_as<telegram_api::updateMessageID>(update);
+        if (!td_->messages_manager_->on_update_message_id(
+                sent_message_update->random_id_, MessageId(ServerMessageId(sent_message_update->id_)), source)) {
+          for (auto &debug_update : updates) {
+            LOG(ERROR) << "Update: " << oneline(to_string(debug_update));
+          }
+        }
+        processed_updates++;
+        update = nullptr;
+        CHECK(!running_get_difference_);
+      }
+    }
+  }
+
+  for (auto &update : updates) {
+    if (update != nullptr) {
+      int32 id = update->get_id();
+      if (id == telegram_api::updateNewMessage::ID || id == telegram_api::updateReadMessagesContents::ID ||
+          id == telegram_api::updateEditMessage::ID || id == telegram_api::updateDeleteMessages::ID ||
+          id == telegram_api::updateReadHistoryInbox::ID || id == telegram_api::updateReadHistoryOutbox::ID ||
+          id == telegram_api::updateWebPage::ID) {
+        if (!downcast_call(*update, OnUpdate(this, update, false))) {
+          LOG(ERROR) << "Can't call on some update received from " << source;
+        }
+        processed_updates++;
+        update = nullptr;
+      }
+    }
+  }
+
+  if (running_get_difference_) {
+    LOG(INFO) << "Postpone " << updates.size() << " updates [" << seq_begin << ", " << seq_end
+              << "] with date = " << date << " from " << source;
+    postponed_updates_.emplace(seq_begin, PendingUpdates(seq_begin, seq_end, date, std::move(updates)));
+    return;
+  }
+
+  set_state(State::Type::General);
+
+  if (processed_updates == updates.size()) {
+    if (seq_begin || seq_end) {
+      LOG(ERROR) << "All updates from " << source << " was processed but seq = " << seq_
+                 << ", seq_begin = " << seq_begin << ", seq_end = " << seq_end;
+    } else {
+      LOG(INFO) << "All updates was processed";
+    }
+    return;
+  }
+
+  if (seq_begin == 0 || seq_begin == seq_ + 1) {
+    LOG(INFO) << "Process " << updates.size() << " updates [" << seq_begin << ", " << seq_end
+              << "] with date = " << date << " from " << source;
+    process_seq_updates(seq_end, date, std::move(updates));
+    process_pending_seq_updates();
+    return;
+  }
+
+  if (seq_begin <= seq_) {
+    if (seq_end > seq_) {
+      LOG(ERROR) << "Strange updates from " << source << " coming with seq_begin = " << seq_begin
+                 << ", seq_end = " << seq_end << ", but seq = " << seq_;
+    } else {
+      LOG(INFO) << "Old updates from " << source << " coming with seq_begin = " << seq_begin
+                << ", seq_end = " << seq_end << ", but seq = " << seq_;
+    }
+    return;
+  }
+
+  LOG(INFO) << "Gap in seq has found. Receive " << updates.size() << " updates [" << seq_begin << ", " << seq_end
+            << "] from " << source << ", but seq = " << seq_;
+  LOG_IF(WARNING, pending_seq_updates_.find(seq_begin) != pending_seq_updates_.end())
+      << "Already have pending updates with seq = " << seq_begin << ", but receive it again from " << source;
+
+  pending_seq_updates_.emplace(seq_begin, PendingUpdates(seq_begin, seq_end, date, std::move(updates)));
+  set_seq_gap_timeout(MAX_UNFILLED_GAP_TIME);
+}
+
+void UpdatesManager::process_updates(vector<tl_object_ptr<telegram_api::Update>> &&updates, bool force_apply) {
+  tl_object_ptr<telegram_api::updatePtsChanged> update_pts_changed;
+  /*
+    for (auto &update : updates) {
+      if (update != nullptr) {
+        // TODO can't apply it here, because dialog may not be created yet
+        // process updateReadChannelInbox before updateNewChannelMessage
+        auto constructor_id = update->get_id();
+        if (constructor_id == telegram_api::updateReadChannelInbox::ID) {
+          on_update(move_tl_object_as<telegram_api::updateReadChannelInbox>(update), force_apply);
+        }
+      }
+    }
+  */
+  for (auto &update : updates) {
+    if (update != nullptr) {
+      // process updateNewChannelMessage first
+      auto constructor_id = update->get_id();
+      if (constructor_id == telegram_api::updateNewChannelMessage::ID) {
+        on_update(move_tl_object_as<telegram_api::updateNewChannelMessage>(update), force_apply);
+      }
+
+      // updatePtsChanged forces get difference, so process it last
+      if (constructor_id == telegram_api::updatePtsChanged::ID) {
+        update_pts_changed = move_tl_object_as<telegram_api::updatePtsChanged>(update);
+      }
+    }
+  }
+  for (auto &update : updates) {
+    if (update != nullptr) {
+      LOG(INFO) << "Process update " << to_string(update);
+      if (!downcast_call(*update, OnUpdate(this, update, force_apply))) {
+        LOG(ERROR) << "Can't call on some update";
+      }
+      CHECK(!running_get_difference_);
+    }
+  }
+  if (update_pts_changed != nullptr) {
+    on_update(std::move(update_pts_changed), force_apply);
+  }
+}
+
+void UpdatesManager::process_seq_updates(int32 seq_end, int32 date,
+                                         vector<tl_object_ptr<telegram_api::Update>> &&updates) {
+  set_state(State::Type::ApplyingSeqUpdates);
+
+  string serialized_updates = PSTRING() << "process_seq_updates [seq_ = " << seq_ << ", seq_end = " << seq_end << "]: ";
+  // TODO remove after bugs will be fixed
+  for (auto &update : updates) {
+    if (update != nullptr) {
+      serialized_updates += oneline(to_string(update));
+    }
+  }
+  process_updates(std::move(updates), false);
+  if (seq_end) {
+    seq_ = seq_end;
+  }
+  if (date && seq_end) {
+    set_date(date, true, std::move(serialized_updates));
+  }
+
+  if (!running_get_difference_) {
+    set_state(State::Type::General);
+  }
+}
+
+void UpdatesManager::process_pending_seq_updates() {
+  while (!pending_seq_updates_.empty() && !running_get_difference_) {
+    auto update_it = pending_seq_updates_.begin();
+    auto seq_begin = update_it->second.seq_begin;
+    if (seq_begin > seq_ + 1) {
+      break;
+    }
+    if (seq_begin == seq_ + 1) {
+      process_seq_updates(update_it->second.seq_end, update_it->second.date, std::move(update_it->second.updates));
+    } else {
+      // old update
+      CHECK(seq_begin != 0);
+      LOG_IF(ERROR, update_it->second.seq_end > seq_)
+          << "Strange updates coming with seq_begin = " << seq_begin << ", seq_end = " << update_it->second.seq_end
+          << ", but seq = " << seq_;
+    }
+    pending_seq_updates_.erase(update_it);
+  }
+  if (pending_seq_updates_.empty()) {
+    seq_gap_timeout_.cancel_timeout();
+  }
+}
+
+void UpdatesManager::set_seq_gap_timeout(double timeout) {
+  if (!seq_gap_timeout_.has_timeout()) {
+    seq_gap_timeout_.set_callback(std::move(fill_seq_gap));
+    seq_gap_timeout_.set_callback_data(static_cast<void *>(td_));
+    seq_gap_timeout_.set_timeout_in(timeout);
+  }
+}
+
+void UpdatesManager::on_pending_update(tl_object_ptr<telegram_api::Update> update, int32 seq, const char *source) {
+  vector<tl_object_ptr<telegram_api::Update>> v;
+  v.push_back(std::move(update));
+
+  on_pending_updates(std::move(v), seq, seq, 0, source);  // TODO can be optimized
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateNewMessage> update, bool force_apply) {
+  CHECK(update != nullptr);
+  int new_pts = update->pts_;
+  int pts_count = update->pts_count_;
+  td_->messages_manager_->add_pending_update(std::move(update), new_pts, pts_count, force_apply, "on_updateNewMessage");
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateNewChannelMessage> update, bool /*force_apply*/) {
+  CHECK(update != nullptr);
+  td_->messages_manager_->on_update_new_channel_message(std::move(update));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateMessageID> update, bool force_apply) {
+  CHECK(update != nullptr);
+  if (!force_apply) {
+    LOG(ERROR) << "Receive updateMessageID not in getDifference";
+    return;
+  }
+  LOG(INFO) << "Receive update about sent message " << to_string(update);
+  td_->messages_manager_->on_update_message_id(update->random_id_, MessageId(ServerMessageId(update->id_)),
+                                               "getDifference");
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateReadMessagesContents> update, bool force_apply) {
+  CHECK(update != nullptr);
+  int new_pts = update->pts_;
+  int pts_count = update->pts_count_;
+  td_->messages_manager_->add_pending_update(std::move(update), new_pts, pts_count, force_apply,
+                                             "on_updateReadMessagesContents");
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateEditMessage> update, bool force_apply) {
+  CHECK(update != nullptr);
+  int new_pts = update->pts_;
+  int pts_count = update->pts_count_;
+  td_->messages_manager_->add_pending_update(std::move(update), new_pts, pts_count, force_apply,
+                                             "on_updateEditMessage");
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateDeleteMessages> update, bool force_apply) {
+  CHECK(update != nullptr);
+  int new_pts = update->pts_;
+  int pts_count = update->pts_count_;
+  if (update->messages_.empty()) {
+    td_->messages_manager_->add_pending_update(make_tl_object<dummyUpdate>(), new_pts, pts_count, force_apply,
+                                               "on_updateDeleteMessages");
+  } else {
+    td_->messages_manager_->add_pending_update(std::move(update), new_pts, pts_count, force_apply,
+                                               "on_updateDeleteMessages");
+  }
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateReadHistoryInbox> update, bool force_apply) {
+  CHECK(update != nullptr);
+  int new_pts = update->pts_;
+  int pts_count = update->pts_count_;
+  td_->messages_manager_->add_pending_update(std::move(update), new_pts, pts_count, force_apply,
+                                             "on_updateReadHistoryInbox");
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateReadHistoryOutbox> update, bool force_apply) {
+  CHECK(update != nullptr);
+  int new_pts = update->pts_;
+  int pts_count = update->pts_count_;
+  td_->messages_manager_->add_pending_update(std::move(update), new_pts, pts_count, force_apply,
+                                             "on_updateReadHistoryOutbox");
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateServiceNotification> update, bool /*force_apply*/) {
+  CHECK(update != nullptr);
+  td_->messages_manager_->on_update_service_notification(std::move(update));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateContactRegistered> update, bool /*force_apply*/) {
+  CHECK(update != nullptr);
+  td_->messages_manager_->on_update_contact_registered(std::move(update));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateReadChannelInbox> update, bool /*force_apply*/) {
+  CHECK(update != nullptr);
+  td_->messages_manager_->on_update_read_channel_inbox(std::move(update));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateReadChannelOutbox> update, bool /*force_apply*/) {
+  CHECK(update != nullptr);
+  td_->messages_manager_->on_update_read_channel_outbox(std::move(update));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateChannelReadMessagesContents> update,
+                               bool /*force_apply*/) {
+  td_->messages_manager_->on_update_read_channel_messages_contents(std::move(update));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateChannelTooLong> update, bool force_apply) {
+  td_->messages_manager_->on_update_channel_too_long(std::move(update), force_apply);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateChannel> update, bool /*force_apply*/) {
+  // nothing to do
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateEditChannelMessage> update, bool /*force_apply*/) {
+  td_->messages_manager_->on_update_edit_channel_message(std::move(update));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateDeleteChannelMessages> update, bool /*force_apply*/) {
+  ChannelId channel_id(update->channel_id_);
+  if (!channel_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << channel_id;
+    return;
+  }
+  DialogId dialog_id(channel_id);
+  int new_pts = update->pts_;
+  int pts_count = update->pts_count_;
+  td_->messages_manager_->add_pending_channel_update(dialog_id, std::move(update), new_pts, pts_count,
+                                                     "on_updateDeleteChannelMessages");
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateChannelMessageViews> update, bool /*force_apply*/) {
+  ChannelId channel_id(update->channel_id_);
+  if (!channel_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << channel_id;
+    return;
+  }
+  DialogId dialog_id(channel_id);
+  td_->messages_manager_->on_update_message_views({dialog_id, MessageId(ServerMessageId(update->id_))}, update->views_);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateChannelPinnedMessage> update, bool /*force_apply*/) {
+  td_->contacts_manager_->on_update_channel_pinned_message(ChannelId(update->channel_id_),
+                                                           MessageId(ServerMessageId(update->id_)));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateChannelAvailableMessages> update,
+                               bool /*force_apply*/) {
+  td_->messages_manager_->on_update_channel_max_unavailable_message_id(
+      ChannelId(update->channel_id_), MessageId(ServerMessageId(update->available_min_id_)));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateNotifySettings> update, bool /*force_apply*/) {
+  CHECK(update != nullptr);
+  td_->messages_manager_->on_update_notify_settings(
+      td_->messages_manager_->get_notification_settings_scope(std::move(update->peer_)),
+      std::move(update->notify_settings_));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateWebPage> update, bool force_apply) {
+  CHECK(update != nullptr);
+  td_->web_pages_manager_->on_get_web_page(std::move(update->webpage_), DialogId());
+  td_->messages_manager_->add_pending_update(make_tl_object<dummyUpdate>(), update->pts_, update->pts_count_,
+                                             force_apply, "on_updateWebPage");
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateChannelWebPage> update, bool /*force_apply*/) {
+  CHECK(update != nullptr);
+  td_->web_pages_manager_->on_get_web_page(std::move(update->webpage_), DialogId());
+  ChannelId channel_id(update->channel_id_);
+  if (!channel_id.is_valid()) {
+    LOG(ERROR) << "Receive invalid " << channel_id;
+    return;
+  }
+  DialogId dialog_id(channel_id);
+  td_->messages_manager_->add_pending_channel_update(dialog_id, make_tl_object<dummyUpdate>(), update->pts_,
+                                                     update->pts_count_, "on_updateChannelWebPage");
+}
+
+tl_object_ptr<td_api::ChatAction> UpdatesManager::convert_send_message_action(
+    tl_object_ptr<telegram_api::SendMessageAction> action) {
+  auto fix_progress = [](int32 progress) { return progress <= 0 || progress > 100 ? 0 : progress; };
+
+  switch (action->get_id()) {
+    case telegram_api::sendMessageCancelAction::ID:
+      return make_tl_object<td_api::chatActionCancel>();
+    case telegram_api::sendMessageTypingAction::ID:
+      return make_tl_object<td_api::chatActionTyping>();
+    case telegram_api::sendMessageRecordVideoAction::ID:
+      return make_tl_object<td_api::chatActionRecordingVideo>();
+    case telegram_api::sendMessageUploadVideoAction::ID: {
+      auto upload_video_action = move_tl_object_as<telegram_api::sendMessageUploadVideoAction>(action);
+      return make_tl_object<td_api::chatActionUploadingVideo>(fix_progress(upload_video_action->progress_));
+    }
+    case telegram_api::sendMessageRecordAudioAction::ID:
+      return make_tl_object<td_api::chatActionRecordingVoiceNote>();
+    case telegram_api::sendMessageUploadAudioAction::ID: {
+      auto upload_audio_action = move_tl_object_as<telegram_api::sendMessageUploadAudioAction>(action);
+      return make_tl_object<td_api::chatActionUploadingVoiceNote>(fix_progress(upload_audio_action->progress_));
+    }
+    case telegram_api::sendMessageUploadPhotoAction::ID: {
+      auto upload_photo_action = move_tl_object_as<telegram_api::sendMessageUploadPhotoAction>(action);
+      return make_tl_object<td_api::chatActionUploadingPhoto>(fix_progress(upload_photo_action->progress_));
+    }
+    case telegram_api::sendMessageUploadDocumentAction::ID: {
+      auto upload_document_action = move_tl_object_as<telegram_api::sendMessageUploadDocumentAction>(action);
+      return make_tl_object<td_api::chatActionUploadingDocument>(fix_progress(upload_document_action->progress_));
+    }
+    case telegram_api::sendMessageGeoLocationAction::ID:
+      return make_tl_object<td_api::chatActionChoosingLocation>();
+    case telegram_api::sendMessageChooseContactAction::ID:
+      return make_tl_object<td_api::chatActionChoosingContact>();
+    case telegram_api::sendMessageGamePlayAction::ID:
+      return make_tl_object<td_api::chatActionStartPlayingGame>();
+    case telegram_api::sendMessageRecordRoundAction::ID:
+      return make_tl_object<td_api::chatActionRecordingVideoNote>();
+    case telegram_api::sendMessageUploadRoundAction::ID: {
+      auto upload_round_action = move_tl_object_as<telegram_api::sendMessageUploadRoundAction>(action);
+      return make_tl_object<td_api::chatActionUploadingVideoNote>(fix_progress(upload_round_action->progress_));
+    }
+    default:
+      UNREACHABLE();
+      return make_tl_object<td_api::chatActionTyping>();
+  }
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateUserTyping> update, bool /*force_apply*/) {
+  UserId user_id(update->user_id_);
+  if (!td_->contacts_manager_->have_min_user(user_id)) {
+    LOG(DEBUG) << "Ignore user typing of unknown " << user_id;
+    return;
+  }
+  DialogId dialog_id(user_id);
+  if (!td_->messages_manager_->have_dialog(dialog_id)) {
+    LOG(DEBUG) << "Ignore user typing in unknown " << dialog_id;
+    return;
+  }
+  td_->messages_manager_->on_user_dialog_action(dialog_id, user_id,
+                                                convert_send_message_action(std::move(update->action_)));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateChatUserTyping> update, bool /*force_apply*/) {
+  UserId user_id(update->user_id_);
+  if (!td_->contacts_manager_->have_min_user(user_id)) {
+    LOG(DEBUG) << "Ignore user chat typing of unknown " << user_id;
+    return;
+  }
+  ChatId chat_id(update->chat_id_);
+  DialogId dialog_id(chat_id);
+  if (!td_->messages_manager_->have_dialog(dialog_id)) {
+    ChannelId channel_id(update->chat_id_);
+    dialog_id = DialogId(channel_id);
+    if (!td_->messages_manager_->have_dialog(dialog_id)) {
+      LOG(DEBUG) << "Ignore user chat typing in unknown " << dialog_id;
+      return;
+    }
+  }
+  td_->messages_manager_->on_user_dialog_action(dialog_id, user_id,
+                                                convert_send_message_action(std::move(update->action_)));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateEncryptedChatTyping> update, bool /*force_apply*/) {
+  SecretChatId secret_chat_id(update->chat_id_);
+  DialogId dialog_id(secret_chat_id);
+
+  if (!td_->messages_manager_->have_dialog(dialog_id)) {
+    LOG(DEBUG) << "Ignore secret chat typing in unknown " << dialog_id;
+    return;
+  }
+
+  UserId user_id = td_->contacts_manager_->get_secret_chat_user_id(secret_chat_id);
+  if (!td_->contacts_manager_->have_user_force(user_id)) {
+    LOG(DEBUG) << "Ignore secret chat typing of unknown " << user_id;
+    return;
+  }
+
+  td_->messages_manager_->on_user_dialog_action(dialog_id, user_id, make_tl_object<td_api::chatActionTyping>());
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateUserStatus> update, bool /*force_apply*/) {
+  td_->contacts_manager_->on_update_user_online(UserId(update->user_id_), std::move(update->status_));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateUserName> update, bool /*force_apply*/) {
+  td_->contacts_manager_->on_update_user_name(UserId(update->user_id_), std::move(update->first_name_),
+                                              std::move(update->last_name_), std::move(update->username_));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateUserPhone> update, bool /*force_apply*/) {
+  td_->contacts_manager_->on_update_user_phone_number(UserId(update->user_id_), std::move(update->phone_));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateUserPhoto> update, bool /*force_apply*/) {
+  // TODO update->previous_, update->date_
+  td_->contacts_manager_->on_update_user_photo(UserId(update->user_id_), std::move(update->photo_));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateUserBlocked> update, bool /*force_apply*/) {
+  td_->contacts_manager_->on_update_user_blocked(UserId(update->user_id_), update->blocked_);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateContactLink> update, bool /*force_apply*/) {
+  td_->contacts_manager_->on_update_user_links(UserId(update->user_id_), std::move(update->my_link_),
+                                               std::move(update->foreign_link_));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateChatParticipants> update, bool /*force_apply*/) {
+  td_->contacts_manager_->on_get_chat_participants(std::move(update->participants_));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateChatParticipantAdd> update, bool /*force_apply*/) {
+  td_->contacts_manager_->on_update_chat_add_user(ChatId(update->chat_id_), UserId(update->inviter_id_),
+                                                  UserId(update->user_id_), update->date_, update->version_);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateChatParticipantAdmin> update, bool /*force_apply*/) {
+  td_->contacts_manager_->on_update_chat_edit_administrator(ChatId(update->chat_id_), UserId(update->user_id_),
+                                                            update->is_admin_, update->version_);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateChatParticipantDelete> update, bool /*force_apply*/) {
+  td_->contacts_manager_->on_update_chat_delete_user(ChatId(update->chat_id_), UserId(update->user_id_),
+                                                     update->version_);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateChatAdmins> update, bool /*force_apply*/) {
+  td_->contacts_manager_->on_update_chat_everyone_is_administrator(ChatId(update->chat_id_), !update->enabled_,
+                                                                   update->version_);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateDraftMessage> update, bool /*force_apply*/) {
+  td_->messages_manager_->on_update_dialog_draft_message(DialogId(update->peer_), std::move(update->draft_));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateDialogPinned> update, bool /*force_apply*/) {
+  td_->messages_manager_->on_update_dialog_pinned(
+      DialogId(update->peer_), (update->flags_ & telegram_api::updateDialogPinned::PINNED_MASK) != 0);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updatePinnedDialogs> update, bool /*force_apply*/) {
+  td_->messages_manager_->on_update_pinned_dialogs();  // TODO use update->order_
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateDcOptions> update, bool /*force_apply*/) {
+  send_closure(G()->config_manager(), &ConfigManager::on_dc_options_update, DcOptions(update->dc_options_));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateBotInlineQuery> update, bool /*force_apply*/) {
+  td_->inline_queries_manager_->on_new_query(update->query_id_, UserId(update->user_id_), Location(update->geo_),
+                                             update->query_, update->offset_);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateBotInlineSend> update, bool /*force_apply*/) {
+  td_->inline_queries_manager_->on_chosen_result(UserId(update->user_id_), Location(update->geo_), update->query_,
+                                                 update->id_, std::move(update->msg_id_));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateBotCallbackQuery> update, bool /*force_apply*/) {
+  td_->callback_queries_manager_->on_new_query(update->flags_, update->query_id_, UserId(update->user_id_),
+                                               DialogId(update->peer_), MessageId(ServerMessageId(update->msg_id_)),
+                                               std::move(update->data_), update->chat_instance_,
+                                               std::move(update->game_short_name_));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateInlineBotCallbackQuery> update, bool /*force_apply*/) {
+  td_->callback_queries_manager_->on_new_inline_query(update->flags_, update->query_id_, UserId(update->user_id_),
+                                                      std::move(update->msg_id_), std::move(update->data_),
+                                                      update->chat_instance_, std::move(update->game_short_name_));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateFavedStickers> update, bool /*force_apply*/) {
+  td_->stickers_manager_->reload_favorite_stickers(true);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateSavedGifs> update, bool /*force_apply*/) {
+  td_->animations_manager_->reload_saved_animations(true);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateConfig> update, bool /*force_apply*/) {
+  send_closure(td_->config_manager_, &ConfigManager::request_config);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updatePtsChanged> update, bool /*force_apply*/) {
+  set_pts(std::numeric_limits<int32>::max(), "updatePtsChanged").set_value(Unit());
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateEncryption> update, bool /*force_apply*/) {
+  send_closure(td_->secret_chats_manager_, &SecretChatsManager::on_update_chat, std::move(update));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateNewEncryptedMessage> update, bool force_apply) {
+  send_closure(td_->secret_chats_manager_, &SecretChatsManager::on_update_message, std::move(update), force_apply);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateEncryptedMessagesRead> update, bool /*force_apply*/) {
+  td_->messages_manager_->read_secret_chat_outbox(SecretChatId(update->chat_id_), update->max_date_, update->date_);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updatePrivacy> update, bool /*force_apply*/) {
+  send_closure(td_->privacy_manager_, &PrivacyManager::update_privacy, std::move(update));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateNewStickerSet> update, bool /*force_apply*/) {
+  td_->stickers_manager_->on_get_messages_sticker_set(0, std::move(update->stickerset_), true);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateStickerSets> update, bool /*force_apply*/) {
+  td_->stickers_manager_->on_update_sticker_sets();
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateStickerSetsOrder> update, bool /*force_apply*/) {
+  bool is_masks = (update->flags_ & telegram_api::updateStickerSetsOrder::MASKS_MASK) != 0;
+  td_->stickers_manager_->on_update_sticker_sets_order(is_masks, update->order_);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateReadFeaturedStickers> update, bool /*force_apply*/) {
+  td_->stickers_manager_->reload_featured_sticker_sets(true);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateRecentStickers> update, bool /*force_apply*/) {
+  td_->stickers_manager_->reload_recent_stickers(false, true);
+  td_->stickers_manager_->reload_recent_stickers(true, true);
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateBotShippingQuery> update, bool /*force_apply*/) {
+  UserId user_id(update->user_id_);
+  if (!user_id.is_valid()) {
+    LOG(ERROR) << "Receive shipping query from invalid " << user_id;
+    return;
+  }
+  CHECK(update->shipping_address_ != nullptr);
+
+  send_closure(G()->td(), &Td::send_update,
+               make_tl_object<td_api::updateNewShippingQuery>(
+                   update->query_id_, td_->contacts_manager_->get_user_id_object(user_id, "updateNewShippingQuery"),
+                   update->payload_.as_slice().str(),
+                   get_shipping_address_object(get_shipping_address(
+                       std::move(update->shipping_address_)))));  // TODO use convert_shipping_address
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateBotPrecheckoutQuery> update, bool /*force_apply*/) {
+  UserId user_id(update->user_id_);
+  if (!user_id.is_valid()) {
+    LOG(ERROR) << "Receive pre-checkout query from invalid " << user_id;
+    return;
+  }
+
+  send_closure(G()->td(), &Td::send_update,
+               make_tl_object<td_api::updateNewPreCheckoutQuery>(
+                   update->query_id_, td_->contacts_manager_->get_user_id_object(user_id, "updateNewPreCheckoutQuery"),
+                   update->currency_, update->total_amount_, update->payload_.as_slice().str(),
+                   update->shipping_option_id_, get_order_info_object(get_order_info(std::move(update->info_)))));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateBotWebhookJSON> update, bool /*force_apply*/) {
+  send_closure(G()->td(), &Td::send_update, make_tl_object<td_api::updateNewCustomEvent>(update->data_->data_));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateBotWebhookJSONQuery> update, bool /*force_apply*/) {
+  send_closure(G()->td(), &Td::send_update,
+               make_tl_object<td_api::updateNewCustomQuery>(update->query_id_, update->data_->data_, update->timeout_));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updatePhoneCall> update, bool /*force_apply*/) {
+  send_closure(G()->call_manager(), &CallManager::update_call, std::move(update));
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateContactsReset> update, bool /*force_apply*/) {
+  td_->contacts_manager_->on_update_contacts_reset();
+}
+
+// unsupported updates
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateLangPackTooLong> update, bool /*force_apply*/) {
+}
+
+void UpdatesManager::on_update(tl_object_ptr<telegram_api::updateLangPack> update, bool /*force_apply*/) {
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/UpdatesManager.h b/libs/tdlib/td/td/telegram/UpdatesManager.h
new file mode 100644
index 0000000000..9602fee7ef
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/UpdatesManager.h
@@ -0,0 +1,273 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/DialogId.h"
+#include "td/telegram/PtsManager.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/PromiseFuture.h"
+#include "td/actor/Timeout.h"
+#include "td/utils/common.h"
+
+#include <map>
+#include <unordered_set>
+
+namespace td {
+
+class Td;
+
+class UpdatesManager : public Actor {
+ public:
+  UpdatesManager(Td *td, ActorShared<> parent);
+
+  void on_get_updates(tl_object_ptr<telegram_api::Updates> &&updates_ptr);
+
+  void on_get_updates_state(tl_object_ptr<telegram_api::updates_state> &&state, const char *source);
+
+  void on_get_difference(tl_object_ptr<telegram_api::updates_Difference> &&difference_ptr);
+
+  std::unordered_set<int64> get_sent_messages_random_ids(const telegram_api::Updates *updates_ptr);
+
+  vector<const tl_object_ptr<telegram_api::Message> *> get_new_messages(const telegram_api::Updates *updates_ptr);
+
+  vector<DialogId> get_chats(const telegram_api::Updates *updates_ptr);
+
+  void get_difference(const char *source);
+
+  void schedule_get_difference(const char *source);
+
+  void init_state();
+
+  void ping_server();
+
+  void on_server_pong(tl_object_ptr<telegram_api::updates_state> &&state);
+
+  int32 get_pts() const {
+    return pts_manager_.mem_pts();
+  }
+  int32 get_qts() const {
+    return qts_;
+  }
+  int32 get_date() const {
+    return date_;
+  }
+
+  string get_state() const;  // for debug purposes only
+
+  Promise<> set_pts(int32 pts, const char *source) TD_WARN_UNUSED_RESULT;
+
+  void set_qts(int32 qts);
+
+  static const double MAX_UNFILLED_GAP_TIME;
+
+  static void fill_pts_gap(void *td);
+
+  bool running_get_difference() const {
+    return running_get_difference_;
+  }
+
+ private:
+  static constexpr int32 FORCED_GET_DIFFERENCE_PTS_DIFF = 100000;
+
+  friend class OnUpdate;
+
+  class PendingUpdates {
+   public:
+    int32 seq_begin;
+    int32 seq_end;
+    int32 date;
+    vector<tl_object_ptr<telegram_api::Update>> updates;
+
+    PendingUpdates(int32 seq_begin, int32 seq_end, int32 date, vector<tl_object_ptr<telegram_api::Update>> &&updates)
+        : seq_begin(seq_begin), seq_end(seq_end), date(date), updates(std::move(updates)) {
+    }
+  };
+
+  Td *td_;
+  ActorShared<> parent_;
+
+  PtsManager pts_manager_;
+  int32 qts_ = 0;
+  int32 date_ = 0;
+  int32 seq_ = 0;
+  string date_source_ = "nowhere";
+
+  std::multimap<int32, PendingUpdates> postponed_updates_;    // updates received during getDifference
+  std::multimap<int32, PendingUpdates> pending_seq_updates_;  // updates with too big seq
+
+  Timeout seq_gap_timeout_;
+
+  int32 retry_time_ = 1;
+  Timeout retry_timeout_;
+
+  bool running_get_difference_ = false;
+  int32 last_get_difference_pts_ = 0;
+
+  class State {
+   public:
+    enum class Type {
+      General,
+      RunningGetUpdatesState,
+      RunningGetDifference,
+      ApplyingDifference,
+      ApplyingDifferenceSlice,
+      ApplyingUpdates,
+      ApplyingSeqUpdates
+    };
+    Type type = Type::General;
+    int32 pts = -1;
+    int32 qts = -1;
+    int32 date = -1;
+  };
+
+  State state_;  // for debug purposes only
+
+  void set_state(State::Type type);  // for debug purposes only
+
+  void tear_down() override;
+
+  Promise<> add_pts(int32 pts);
+  void on_pts_ack(PtsManager::PtsId ack_token);
+  void save_pts(int32 pts);
+
+  void set_date(int32 date, bool from_update, string date_source);
+
+  static tl_object_ptr<td_api::ChatAction> convert_send_message_action(
+      tl_object_ptr<telegram_api::SendMessageAction> action);
+
+  void process_get_difference_updates(vector<tl_object_ptr<telegram_api::Message>> &&new_messages,
+                                      vector<tl_object_ptr<telegram_api::EncryptedMessage>> &&new_encrypted_messages,
+                                      int32 qts, vector<tl_object_ptr<telegram_api::Update>> &&other_updates);
+
+  void on_pending_update(tl_object_ptr<telegram_api::Update> update, int32 seq, const char *source);
+
+  void on_pending_updates(vector<tl_object_ptr<telegram_api::Update>> &&updates, int32 seq_begin, int32 seq_end,
+                          int32 date, const char *source);
+
+  void process_updates(vector<tl_object_ptr<telegram_api::Update>> &&updates, bool force_apply);
+
+  void process_seq_updates(int32 seq_end, int32 date, vector<tl_object_ptr<telegram_api::Update>> &&updates);
+
+  void process_pending_seq_updates();
+
+  static void fill_seq_gap(void *td);
+
+  static void fill_get_difference_gap(void *td);
+
+  static void fill_gap(void *td, const char *source);
+
+  void set_seq_gap_timeout(double timeout);
+
+  void on_failed_get_difference();
+
+  void before_get_difference();
+
+  void after_get_difference();
+
+  bool is_acceptable_message_entities(const vector<tl_object_ptr<telegram_api::MessageEntity>> &message_entities) const;
+
+  bool is_acceptable_message(const telegram_api::Message *message_ptr) const;
+
+  bool is_acceptable_update(const telegram_api::Update *update) const;
+
+  void on_update(tl_object_ptr<telegram_api::updateNewMessage> update, bool force_apply);
+  void on_update(tl_object_ptr<telegram_api::updateMessageID> update, bool force_apply);
+  void on_update(tl_object_ptr<telegram_api::updateReadMessagesContents> update, bool force_apply);
+  void on_update(tl_object_ptr<telegram_api::updateEditMessage> update, bool force_apply);
+  void on_update(tl_object_ptr<telegram_api::updateDeleteMessages> update, bool force_apply);
+  void on_update(tl_object_ptr<telegram_api::updateReadHistoryInbox> update, bool force_apply);
+  void on_update(tl_object_ptr<telegram_api::updateReadHistoryOutbox> update, bool force_apply);
+  void on_update(tl_object_ptr<telegram_api::updateNotifySettings> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateWebPage> update, bool force_apply);
+  void on_update(tl_object_ptr<telegram_api::updateChannelWebPage> update, bool force_apply);
+
+  void on_update(tl_object_ptr<telegram_api::updateUserTyping> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateChatUserTyping> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateEncryptedChatTyping> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateUserStatus> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateUserName> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateUserPhone> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateUserPhoto> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateUserBlocked> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateContactLink> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateChatParticipants> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateChatParticipantAdd> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateChatParticipantAdmin> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateChatParticipantDelete> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateChatAdmins> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateServiceNotification> update, bool force_apply);
+  void on_update(tl_object_ptr<telegram_api::updateContactRegistered> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateDcOptions> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateNewChannelMessage> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateReadChannelInbox> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateReadChannelOutbox> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateChannelReadMessagesContents> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateChannelTooLong> update, bool force_apply);
+  void on_update(tl_object_ptr<telegram_api::updateChannel> update, bool force_apply);
+  void on_update(tl_object_ptr<telegram_api::updateEditChannelMessage> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateDeleteChannelMessages> update, bool force_apply);
+  void on_update(tl_object_ptr<telegram_api::updateChannelMessageViews> update, bool force_apply);
+  void on_update(tl_object_ptr<telegram_api::updateChannelPinnedMessage> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateChannelAvailableMessages> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateDraftMessage> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateDialogPinned> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updatePinnedDialogs> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateBotInlineQuery> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateBotInlineSend> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateBotCallbackQuery> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateInlineBotCallbackQuery> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateFavedStickers> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateSavedGifs> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateConfig> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updatePtsChanged> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updatePrivacy> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateEncryption> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateNewEncryptedMessage> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateEncryptedMessagesRead> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateNewStickerSet> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateStickerSets> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateStickerSetsOrder> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateReadFeaturedStickers> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateRecentStickers> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateBotShippingQuery> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateBotPrecheckoutQuery> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateBotWebhookJSON> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateBotWebhookJSONQuery> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updatePhoneCall> update, bool /*force_apply*/);
+
+  void on_update(tl_object_ptr<telegram_api::updateContactsReset> update, bool /*force_apply*/);
+
+  // unsupported updates
+
+  void on_update(tl_object_ptr<telegram_api::updateLangPackTooLong> update, bool /*force_apply*/);
+  void on_update(tl_object_ptr<telegram_api::updateLangPack> update, bool /*force_apply*/);
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/UserId.h b/libs/tdlib/td/td/telegram/UserId.h
new file mode 100644
index 0000000000..d7088b8645
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/UserId.h
@@ -0,0 +1,65 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/StringBuilder.h"
+
+#include <functional>
+#include <type_traits>
+
+namespace td {
+
+class UserId {
+  int32 id = 0;
+
+ public:
+  UserId() = default;
+
+  explicit UserId(int32 user_id) : id(user_id) {
+  }
+  template <class T, typename = std::enable_if_t<std::is_convertible<T, int32>::value>>
+  UserId(T user_id) = delete;
+
+  bool is_valid() const {
+    return id > 0;
+  }
+
+  int32 get() const {
+    return id;
+  }
+
+  bool operator==(const UserId &other) const {
+    return id == other.id;
+  }
+
+  bool operator!=(const UserId &other) const {
+    return id != other.id;
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    storer.store_int(id);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    id = parser.fetch_int();
+  }
+};
+
+struct UserIdHash {
+  std::size_t operator()(UserId user_id) const {
+    return std::hash<int32>()(user_id.get());
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &string_builder, UserId user_id) {
+  return string_builder << "user " << user_id.get();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/Version.h b/libs/tdlib/td/td/telegram/Version.h
new file mode 100644
index 0000000000..f27c3b77be
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/Version.h
@@ -0,0 +1,43 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+namespace td {
+
+enum class Version : int32 {
+  Initial,
+  StoreFileId,
+  AddKeyHashToSecretChat,
+  AddDurationToAnimation,
+  FixStoreGameWithoutAnimation,
+  AddAccessHashToSecretChat,
+  StoreFileOwnerId,
+  StoreFileEncryptionKey,
+  NetStatsCountDuration,
+  FixWebPageInstantViewDatabase,
+  FixMinUsers,
+  FixPageBlockAudioEmptyFile,
+  AddMessageInvoiceProviderData,
+  AddCaptionEntities,
+  Next
+};
+
+enum class DbVersion : int32 {
+  DialogDbCreated = 3,
+  MessagesDbMediaIndex,
+  MessagesDb30MediaIndex,
+  MessagesDbFts,
+  MessagesCallIndex,
+  FixFileRemoteLocationKeyBug,
+  Next
+};
+
+inline int32 current_db_version() {
+  return static_cast<int32>(DbVersion::Next) - 1;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/VideoNotesManager.cpp b/libs/tdlib/td/td/telegram/VideoNotesManager.cpp
new file mode 100644
index 0000000000..e83fefa582
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/VideoNotesManager.cpp
@@ -0,0 +1,230 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/VideoNotesManager.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/DocumentsManager.h"
+#include "td/telegram/files/FileManager.h"
+#include "td/telegram/SecretChatActor.h"
+#include "td/telegram/Td.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+VideoNotesManager::VideoNotesManager(Td *td) : td_(td) {
+}
+
+int32 VideoNotesManager::get_video_note_duration(FileId file_id) {
+  auto &video_note = video_notes_[file_id];
+  CHECK(video_note != nullptr);
+  return video_note->duration;
+}
+
+tl_object_ptr<td_api::videoNote> VideoNotesManager::get_video_note_object(FileId file_id) {
+  if (!file_id.is_valid()) {
+    return nullptr;
+  }
+
+  auto &video_note = video_notes_[file_id];
+  CHECK(video_note != nullptr);
+  video_note->is_changed = false;
+
+  return make_tl_object<td_api::videoNote>(video_note->duration, video_note->dimensions.width,
+                                           get_photo_size_object(td_->file_manager_.get(), &video_note->thumbnail),
+                                           td_->file_manager_->get_file_object(file_id));
+}
+
+FileId VideoNotesManager::on_get_video_note(std::unique_ptr<VideoNote> new_video_note, bool replace) {
+  auto file_id = new_video_note->file_id;
+  LOG(INFO) << "Receive video note " << file_id;
+  auto &v = video_notes_[file_id];
+  if (v == nullptr) {
+    v = std::move(new_video_note);
+  } else if (replace) {
+    CHECK(v->file_id == new_video_note->file_id);
+    if (v->duration != new_video_note->duration || v->dimensions != new_video_note->dimensions) {
+      LOG(DEBUG) << "Video note " << file_id << " info has changed";
+      v->duration = new_video_note->duration;
+      v->dimensions = new_video_note->dimensions;
+      v->is_changed = true;
+    }
+    if (v->thumbnail != new_video_note->thumbnail) {
+      if (!v->thumbnail.file_id.is_valid()) {
+        LOG(DEBUG) << "Video note " << file_id << " thumbnail has changed";
+      } else {
+        LOG(INFO) << "Video note " << file_id << " thumbnail has changed from " << v->thumbnail << " to "
+                  << new_video_note->thumbnail;
+      }
+      v->thumbnail = new_video_note->thumbnail;
+      v->is_changed = true;
+    }
+  }
+  return file_id;
+}
+
+const VideoNotesManager::VideoNote *VideoNotesManager::get_video_note(FileId file_id) const {
+  auto video_note = video_notes_.find(file_id);
+  if (video_note == video_notes_.end()) {
+    return nullptr;
+  }
+
+  CHECK(video_note->second->file_id == file_id);
+  return video_note->second.get();
+}
+
+FileId VideoNotesManager::get_video_note_thumbnail_file_id(FileId file_id) const {
+  auto video_note = get_video_note(file_id);
+  CHECK(video_note != nullptr);
+  return video_note->thumbnail.file_id;
+}
+
+void VideoNotesManager::delete_video_note_thumbnail(FileId file_id) {
+  auto &video_note = video_notes_[file_id];
+  CHECK(video_note != nullptr);
+  video_note->thumbnail = PhotoSize();
+}
+
+FileId VideoNotesManager::dup_video_note(FileId new_id, FileId old_id) {
+  const VideoNote *old_video_note = get_video_note(old_id);
+  CHECK(old_video_note != nullptr);
+  auto &new_video_note = video_notes_[new_id];
+  CHECK(!new_video_note);
+  new_video_note = std::make_unique<VideoNote>(*old_video_note);
+  new_video_note->file_id = new_id;
+  new_video_note->thumbnail.file_id = td_->file_manager_->dup_file_id(new_video_note->thumbnail.file_id);
+  return new_id;
+}
+
+bool VideoNotesManager::merge_video_notes(FileId new_id, FileId old_id, bool can_delete_old) {
+  if (!old_id.is_valid()) {
+    LOG(ERROR) << "Old file id is invalid";
+    return true;
+  }
+
+  LOG(INFO) << "Merge video notes " << new_id << " and " << old_id;
+  const VideoNote *old_ = get_video_note(old_id);
+  CHECK(old_ != nullptr);
+  if (old_id == new_id) {
+    return old_->is_changed;
+  }
+
+  auto new_it = video_notes_.find(new_id);
+  if (new_it == video_notes_.end()) {
+    auto &old = video_notes_[old_id];
+    old->is_changed = true;
+    if (!can_delete_old) {
+      dup_video_note(new_id, old_id);
+    } else {
+      old->file_id = new_id;
+      video_notes_.emplace(new_id, std::move(old));
+    }
+  } else {
+    VideoNote *new_ = new_it->second.get();
+    CHECK(new_ != nullptr);
+    new_->is_changed = true;
+    if (old_->thumbnail != new_->thumbnail) {
+      //    LOG_STATUS(td_->file_manager_->merge(new_->thumbnail.file_id, old_->thumbnail.file_id));
+    }
+  }
+  LOG_STATUS(td_->file_manager_->merge(new_id, old_id));
+  if (can_delete_old) {
+    video_notes_.erase(old_id);
+  }
+  return true;
+}
+
+void VideoNotesManager::create_video_note(FileId file_id, PhotoSize thumbnail, int32 duration, Dimensions dimensions,
+                                          bool replace) {
+  auto v = make_unique<VideoNote>();
+  v->file_id = file_id;
+  v->duration = max(duration, 0);
+  if (dimensions.width == dimensions.height && dimensions.width <= 640) {
+    v->dimensions = dimensions;
+  } else {
+    LOG(INFO) << "Receive wrong video note dimensions " << dimensions;
+  }
+  v->thumbnail = std::move(thumbnail);
+  on_get_video_note(std::move(v), replace);
+}
+
+SecretInputMedia VideoNotesManager::get_secret_input_media(FileId video_note_file_id,
+                                                           tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                                           BufferSlice thumbnail, int32 layer) const {
+  const VideoNote *video_note = get_video_note(video_note_file_id);
+  CHECK(video_note != nullptr);
+  auto file_view = td_->file_manager_->get_file_view(video_note_file_id);
+  auto &encryption_key = file_view.encryption_key();
+  if (encryption_key.empty()) {
+    return SecretInputMedia{};
+  }
+  if (file_view.has_remote_location()) {
+    input_file = file_view.remote_location().as_input_encrypted_file();
+  }
+  if (!input_file) {
+    return SecretInputMedia{};
+  }
+  if (video_note->thumbnail.file_id.is_valid() && thumbnail.empty()) {
+    return SecretInputMedia{};
+  }
+  CHECK(layer >= SecretChatActor::VOICE_NOTES_LAYER);
+  vector<tl_object_ptr<secret_api::DocumentAttribute>> attributes;
+  attributes.push_back(make_tl_object<secret_api::documentAttributeVideo66>(
+      secret_api::documentAttributeVideo66::Flags::ROUND_MESSAGE_MASK, true, video_note->duration,
+      video_note->dimensions.width, video_note->dimensions.height));
+  return SecretInputMedia{
+      std::move(input_file),
+      make_tl_object<secret_api::decryptedMessageMediaDocument>(
+          std::move(thumbnail), video_note->thumbnail.dimensions.width, video_note->thumbnail.dimensions.height,
+          "video/mp4", narrow_cast<int32>(file_view.size()), BufferSlice(encryption_key.key_slice()),
+          BufferSlice(encryption_key.iv_slice()), std::move(attributes), "")};
+}
+
+tl_object_ptr<telegram_api::InputMedia> VideoNotesManager::get_input_media(
+    FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file,
+    tl_object_ptr<telegram_api::InputFile> input_thumbnail) const {
+  auto file_view = td_->file_manager_->get_file_view(file_id);
+  if (file_view.is_encrypted()) {
+    return nullptr;
+  }
+  if (file_view.has_remote_location() && !file_view.remote_location().is_web()) {
+    return make_tl_object<telegram_api::inputMediaDocument>(0, file_view.remote_location().as_input_document(), 0);
+  }
+  if (file_view.has_url()) {
+    return make_tl_object<telegram_api::inputMediaDocumentExternal>(0, file_view.url(), 0);
+  }
+  CHECK(!file_view.has_remote_location());
+
+  if (input_file != nullptr) {
+    const VideoNote *video_note = get_video_note(file_id);
+    CHECK(video_note != nullptr);
+
+    vector<tl_object_ptr<telegram_api::DocumentAttribute>> attributes;
+    attributes.push_back(make_tl_object<telegram_api::documentAttributeVideo>(
+        telegram_api::documentAttributeVideo::ROUND_MESSAGE_MASK, false /*ignored*/, false /*ignored*/,
+        video_note->duration, video_note->dimensions.width ? video_note->dimensions.width : 240,
+        video_note->dimensions.height ? video_note->dimensions.height : 240));
+    int32 flags = 0;
+    if (input_thumbnail != nullptr) {
+      flags |= telegram_api::inputMediaUploadedDocument::THUMB_MASK;
+    }
+    return make_tl_object<telegram_api::inputMediaUploadedDocument>(
+        flags, false /*ignored*/, std::move(input_file), std::move(input_thumbnail), "video/mp4", std::move(attributes),
+        vector<tl_object_ptr<telegram_api::InputDocument>>(), 0);
+  }
+
+  return nullptr;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/VideoNotesManager.h b/libs/tdlib/td/td/telegram/VideoNotesManager.h
new file mode 100644
index 0000000000..f5babe801c
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/VideoNotesManager.h
@@ -0,0 +1,79 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/files/FileId.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/SecretInputMedia.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+
+#include <unordered_map>
+
+namespace td {
+class Td;
+}  // namespace td
+
+namespace td {
+
+class VideoNotesManager {
+ public:
+  explicit VideoNotesManager(Td *td);
+
+  int32 get_video_note_duration(FileId file_id);
+
+  tl_object_ptr<td_api::videoNote> get_video_note_object(FileId file_id);
+
+  void create_video_note(FileId file_id, PhotoSize thumbnail, int32 duration, Dimensions dimensions, bool replace);
+
+  tl_object_ptr<telegram_api::InputMedia> get_input_media(FileId file_id,
+                                                          tl_object_ptr<telegram_api::InputFile> input_file,
+                                                          tl_object_ptr<telegram_api::InputFile> input_thumbnail) const;
+
+  SecretInputMedia get_secret_input_media(FileId video_note_file_id,
+                                          tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                          BufferSlice thumbnail, int32 layer) const;
+
+  FileId get_video_note_thumbnail_file_id(FileId file_id) const;
+
+  void delete_video_note_thumbnail(FileId file_id);
+
+  FileId dup_video_note(FileId new_id, FileId old_id);
+
+  bool merge_video_notes(FileId new_id, FileId old_id, bool can_delete_old);
+
+  template <class T>
+  void store_video_note(FileId file_id, T &storer) const;
+
+  template <class T>
+  FileId parse_video_note(T &parser);
+
+ private:
+  class VideoNote {
+   public:
+    int32 duration = 0;
+    Dimensions dimensions;
+    PhotoSize thumbnail;
+
+    FileId file_id;
+
+    bool is_changed = true;
+  };
+
+  const VideoNote *get_video_note(FileId file_id) const;
+
+  FileId on_get_video_note(std::unique_ptr<VideoNote> new_video_note, bool replace);
+
+  Td *td_;
+  std::unordered_map<FileId, unique_ptr<VideoNote>, FileIdHash> video_notes_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/VideoNotesManager.hpp b/libs/tdlib/td/td/telegram/VideoNotesManager.hpp
new file mode 100644
index 0000000000..5992848c97
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/VideoNotesManager.hpp
@@ -0,0 +1,39 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/telegram/VideoNotesManager.h"
+
+#include "td/telegram/files/FileId.hpp"
+#include "td/telegram/Photo.hpp"
+
+#include "td/utils/logging.h"
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+
+template <class T>
+void VideoNotesManager::store_video_note(FileId file_id, T &storer) const {
+  auto it = video_notes_.find(file_id);
+  CHECK(it != video_notes_.end());
+  const VideoNote *video_note = it->second.get();
+  store(video_note->duration, storer);
+  store(video_note->dimensions, storer);
+  store(video_note->thumbnail, storer);
+  store(file_id, storer);
+}
+
+template <class T>
+FileId VideoNotesManager::parse_video_note(T &parser) {
+  auto video_note = make_unique<VideoNote>();
+  parse(video_note->duration, parser);
+  parse(video_note->dimensions, parser);
+  parse(video_note->thumbnail, parser);
+  parse(video_note->file_id, parser);
+  return on_get_video_note(std::move(video_note), true);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/VideosManager.cpp b/libs/tdlib/td/td/telegram/VideosManager.cpp
new file mode 100644
index 0000000000..0d171cd871
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/VideosManager.cpp
@@ -0,0 +1,295 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/VideosManager.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/AuthManager.h"
+#include "td/telegram/DocumentsManager.h"
+#include "td/telegram/files/FileManager.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/Td.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+VideosManager::VideosManager(Td *td) : td_(td) {
+}
+
+int32 VideosManager::get_video_duration(FileId file_id) {
+  auto &video = videos_[file_id];
+  CHECK(video != nullptr);
+  return video->duration;
+}
+
+tl_object_ptr<td_api::video> VideosManager::get_video_object(FileId file_id) {
+  if (!file_id.is_valid()) {
+    return nullptr;
+  }
+
+  auto &video = videos_[file_id];
+  CHECK(video != nullptr);
+  video->is_changed = false;
+
+  return make_tl_object<td_api::video>(
+      video->duration, video->dimensions.width, video->dimensions.height, video->file_name, video->mime_type,
+      video->has_stickers, video->supports_streaming,
+      get_photo_size_object(td_->file_manager_.get(), &video->thumbnail), td_->file_manager_->get_file_object(file_id));
+}
+
+FileId VideosManager::on_get_video(std::unique_ptr<Video> new_video, bool replace) {
+  auto file_id = new_video->file_id;
+  LOG(INFO) << "Receive video " << file_id;
+  auto &v = videos_[file_id];
+  if (v == nullptr) {
+    v = std::move(new_video);
+  } else if (replace) {
+    CHECK(v->file_id == new_video->file_id);
+    if (v->mime_type != new_video->mime_type) {
+      LOG(DEBUG) << "Video " << file_id << " MIME type has changed";
+      v->mime_type = new_video->mime_type;
+      v->is_changed = true;
+    }
+    if (v->duration != new_video->duration || v->dimensions != new_video->dimensions ||
+        v->supports_streaming != new_video->supports_streaming) {
+      LOG(DEBUG) << "Video " << file_id << " info has changed";
+      v->duration = new_video->duration;
+      v->dimensions = new_video->dimensions;
+      v->supports_streaming = new_video->supports_streaming;
+      v->is_changed = true;
+    }
+    if (v->file_name != new_video->file_name) {
+      LOG(DEBUG) << "Video " << file_id << " file name has changed";
+      v->file_name = std::move(new_video->file_name);
+      v->is_changed = true;
+    }
+    if (v->thumbnail != new_video->thumbnail) {
+      if (!v->thumbnail.file_id.is_valid()) {
+        LOG(DEBUG) << "Video " << file_id << " thumbnail has changed";
+      } else {
+        LOG(INFO) << "Video " << file_id << " thumbnail has changed from " << v->thumbnail << " to "
+                  << new_video->thumbnail;
+      }
+      v->thumbnail = new_video->thumbnail;
+      v->is_changed = true;
+    }
+    if (v->has_stickers != new_video->has_stickers && new_video->has_stickers) {
+      v->has_stickers = new_video->has_stickers;
+      v->is_changed = true;
+    }
+    if (v->sticker_file_ids != new_video->sticker_file_ids && !new_video->sticker_file_ids.empty()) {
+      v->sticker_file_ids = new_video->sticker_file_ids;
+      v->is_changed = true;
+    }
+  }
+  return file_id;
+}
+
+const VideosManager::Video *VideosManager::get_video(FileId file_id) const {
+  auto video = videos_.find(file_id);
+  if (video == videos_.end()) {
+    return nullptr;
+  }
+
+  CHECK(video->second->file_id == file_id);
+  return video->second.get();
+}
+
+FileId VideosManager::get_video_thumbnail_file_id(FileId file_id) const {
+  auto video = get_video(file_id);
+  CHECK(video != nullptr);
+  return video->thumbnail.file_id;
+}
+
+void VideosManager::delete_video_thumbnail(FileId file_id) {
+  auto &video = videos_[file_id];
+  CHECK(video != nullptr);
+  video->thumbnail = PhotoSize();
+}
+
+FileId VideosManager::dup_video(FileId new_id, FileId old_id) {
+  const Video *old_video = get_video(old_id);
+  CHECK(old_video != nullptr);
+  auto &new_video = videos_[new_id];
+  CHECK(!new_video);
+  new_video = std::make_unique<Video>(*old_video);
+  new_video->file_id = new_id;
+  new_video->thumbnail.file_id = td_->file_manager_->dup_file_id(new_video->thumbnail.file_id);
+  return new_id;
+}
+
+bool VideosManager::merge_videos(FileId new_id, FileId old_id, bool can_delete_old) {
+  if (!old_id.is_valid()) {
+    LOG(ERROR) << "Old file id is invalid";
+    return true;
+  }
+
+  LOG(INFO) << "Merge videos " << new_id << " and " << old_id;
+  const Video *old_ = get_video(old_id);
+  CHECK(old_ != nullptr);
+  if (old_id == new_id) {
+    return old_->is_changed;
+  }
+
+  auto new_it = videos_.find(new_id);
+  if (new_it == videos_.end()) {
+    auto &old = videos_[old_id];
+    old->is_changed = true;
+    if (!can_delete_old) {
+      dup_video(new_id, old_id);
+    } else {
+      old->file_id = new_id;
+      videos_.emplace(new_id, std::move(old));
+    }
+  } else {
+    Video *new_ = new_it->second.get();
+    CHECK(new_ != nullptr);
+
+    if (!old_->mime_type.empty() && old_->mime_type != new_->mime_type) {
+      LOG(INFO) << "Video has changed: mime_type = (" << old_->mime_type << ", " << new_->mime_type << ")";
+    }
+
+    new_->is_changed = true;
+    if (old_->thumbnail != new_->thumbnail) {
+      //    LOG_STATUS(td_->file_manager_->merge(new_->thumbnail.file_id, old_->thumbnail.file_id));
+    }
+  }
+  LOG_STATUS(td_->file_manager_->merge(new_id, old_id));
+  if (can_delete_old) {
+    videos_.erase(old_id);
+  }
+  return true;
+}
+
+void VideosManager::create_video(FileId file_id, PhotoSize thumbnail, bool has_stickers,
+                                 vector<FileId> &&sticker_file_ids, string file_name, string mime_type, int32 duration,
+                                 Dimensions dimensions, bool supports_streaming, bool replace) {
+  auto v = make_unique<Video>();
+  v->file_id = file_id;
+  v->file_name = std::move(file_name);
+  v->mime_type = std::move(mime_type);
+  v->duration = max(duration, 0);
+  v->dimensions = dimensions;
+  v->thumbnail = std::move(thumbnail);
+  v->supports_streaming = supports_streaming;
+  v->has_stickers = has_stickers;
+  v->sticker_file_ids = std::move(sticker_file_ids);
+  on_get_video(std::move(v), replace);
+}
+
+SecretInputMedia VideosManager::get_secret_input_media(FileId video_file_id,
+                                                       tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                                       const string &caption, BufferSlice thumbnail) const {
+  const Video *video = get_video(video_file_id);
+  CHECK(video != nullptr);
+  auto file_view = td_->file_manager_->get_file_view(video_file_id);
+  auto &encryption_key = file_view.encryption_key();
+  if (encryption_key.empty()) {
+    return SecretInputMedia{};
+  }
+  if (file_view.has_remote_location()) {
+    input_file = file_view.remote_location().as_input_encrypted_file();
+  }
+  if (!input_file) {
+    return SecretInputMedia{};
+  }
+  if (video->thumbnail.file_id.is_valid() && thumbnail.empty()) {
+    return {};
+  }
+  return SecretInputMedia{
+      std::move(input_file),
+      make_tl_object<secret_api::decryptedMessageMediaVideo>(
+          std::move(thumbnail), video->thumbnail.dimensions.width, video->thumbnail.dimensions.height, video->duration,
+          video->mime_type, video->dimensions.width, video->dimensions.height, narrow_cast<int32>(file_view.size()),
+          BufferSlice(encryption_key.key_slice()), BufferSlice(encryption_key.iv_slice()), caption)};
+}
+
+tl_object_ptr<telegram_api::InputMedia> VideosManager::get_input_media(
+    FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file,
+    tl_object_ptr<telegram_api::InputFile> input_thumbnail, int32 ttl) const {
+  if (!file_id.is_valid()) {
+    LOG_IF(ERROR, ttl == 0) << "Video has invalid file_id";
+    return nullptr;
+  }
+  auto file_view = td_->file_manager_->get_file_view(file_id);
+  if (file_view.is_encrypted()) {
+    return nullptr;
+  }
+  if (file_view.has_remote_location() && !file_view.remote_location().is_web()) {
+    int32 flags = 0;
+    if (ttl != 0) {
+      flags |= telegram_api::inputMediaDocument::TTL_SECONDS_MASK;
+    }
+    return make_tl_object<telegram_api::inputMediaDocument>(flags, file_view.remote_location().as_input_document(),
+                                                            ttl);
+  }
+  if (file_view.has_url()) {
+    int32 flags = 0;
+    if (ttl != 0) {
+      flags |= telegram_api::inputMediaDocumentExternal::TTL_SECONDS_MASK;
+    }
+    return make_tl_object<telegram_api::inputMediaDocumentExternal>(flags, file_view.url(), ttl);
+  }
+  CHECK(!file_view.has_remote_location());
+
+  if (input_file != nullptr) {
+    const Video *video = get_video(file_id);
+    CHECK(video != nullptr);
+
+    int32 attribute_flags = 0;
+    if (video->supports_streaming) {
+      attribute_flags |= telegram_api::documentAttributeVideo::SUPPORTS_STREAMING_MASK;
+    }
+
+    vector<tl_object_ptr<telegram_api::DocumentAttribute>> attributes;
+    attributes.push_back(make_tl_object<telegram_api::documentAttributeVideo>(
+        attribute_flags, false /*ignored*/, false /*ignored*/, video->duration, video->dimensions.width,
+        video->dimensions.height));
+    if (!video->file_name.empty()) {
+      attributes.push_back(make_tl_object<telegram_api::documentAttributeFilename>(video->file_name));
+    }
+    int32 flags = 0;
+    vector<tl_object_ptr<telegram_api::InputDocument>> added_stickers;
+    if (ttl != 0 || !td_->auth_manager_->is_bot()) {
+      flags |= telegram_api::inputMediaUploadedDocument::NOSOUND_VIDEO_MASK;
+    }
+    if (video->has_stickers) {
+      flags |= telegram_api::inputMediaUploadedDocument::STICKERS_MASK;
+      added_stickers = td_->file_manager_->get_input_documents(video->sticker_file_ids);
+    }
+    string mime_type = video->mime_type;
+    if (!begins_with(mime_type, "video/") || ttl > 0) {
+      mime_type = "video/mp4";
+    }
+    if (ttl != 0) {
+      flags |= telegram_api::inputMediaUploadedDocument::TTL_SECONDS_MASK;
+    }
+    if (input_thumbnail != nullptr) {
+      flags |= telegram_api::inputMediaUploadedDocument::THUMB_MASK;
+    }
+    return make_tl_object<telegram_api::inputMediaUploadedDocument>(
+        flags, false /*ignored*/, std::move(input_file), std::move(input_thumbnail), mime_type, std::move(attributes),
+        std::move(added_stickers), ttl);
+  }
+
+  return nullptr;
+}
+
+string VideosManager::get_video_search_text(FileId file_id) const {
+  auto *video = get_video(file_id);
+  CHECK(video != nullptr);
+  return video->file_name;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/VideosManager.h b/libs/tdlib/td/td/telegram/VideosManager.h
new file mode 100644
index 0000000000..777327138f
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/VideosManager.h
@@ -0,0 +1,91 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/files/FileId.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/SecretInputMedia.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+
+#include <unordered_map>
+
+namespace td {
+class Td;
+}  // namespace td
+
+namespace td {
+
+class VideosManager {
+ public:
+  explicit VideosManager(Td *td);
+
+  int32 get_video_duration(FileId file_id);
+
+  tl_object_ptr<td_api::video> get_video_object(FileId file_id);
+
+  void create_video(FileId file_id, PhotoSize thumbnail, bool has_stickers, vector<FileId> &&sticker_file_ids,
+                    string file_name, string mime_type, int32 duration, Dimensions dimensions, bool supports_streaming,
+                    bool replace);
+
+  tl_object_ptr<telegram_api::InputMedia> get_input_media(FileId file_id,
+                                                          tl_object_ptr<telegram_api::InputFile> input_file,
+                                                          tl_object_ptr<telegram_api::InputFile> input_thumbnail,
+                                                          int32 ttl) const;
+
+  SecretInputMedia get_secret_input_media(FileId video_file_id,
+                                          tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                          const string &caption, BufferSlice thumbnail) const;
+
+  FileId get_video_thumbnail_file_id(FileId file_id) const;
+
+  void delete_video_thumbnail(FileId file_id);
+
+  FileId dup_video(FileId new_id, FileId old_id);
+
+  bool merge_videos(FileId new_id, FileId old_id, bool can_delete_old);
+
+  template <class T>
+  void store_video(FileId file_id, T &storer) const;
+
+  template <class T>
+  FileId parse_video(T &parser);
+
+  string get_video_search_text(FileId file_id) const;
+
+ private:
+  class Video {
+   public:
+    string file_name;
+    string mime_type;
+    int32 duration = 0;
+    Dimensions dimensions;
+    PhotoSize thumbnail;
+
+    bool supports_streaming = false;
+
+    bool has_stickers = false;
+    vector<FileId> sticker_file_ids;
+
+    FileId file_id;
+
+    bool is_changed = true;
+  };
+
+  const Video *get_video(FileId file_id) const;
+
+  FileId on_get_video(std::unique_ptr<Video> new_video, bool replace);
+
+  Td *td_;
+  std::unordered_map<FileId, unique_ptr<Video>, FileIdHash> videos_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/VideosManager.hpp b/libs/tdlib/td/td/telegram/VideosManager.hpp
new file mode 100644
index 0000000000..b93ce4c02c
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/VideosManager.hpp
@@ -0,0 +1,57 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/telegram/VideosManager.h"
+
+#include "td/telegram/files/FileId.hpp"
+#include "td/telegram/Photo.hpp"
+
+#include "td/utils/logging.h"
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+
+template <class T>
+void VideosManager::store_video(FileId file_id, T &storer) const {
+  auto it = videos_.find(file_id);
+  CHECK(it != videos_.end());
+  const Video *video = it->second.get();
+  BEGIN_STORE_FLAGS();
+  STORE_FLAG(video->has_stickers);
+  STORE_FLAG(video->supports_streaming);
+  END_STORE_FLAGS();
+  store(video->file_name, storer);
+  store(video->mime_type, storer);
+  store(video->duration, storer);
+  store(video->dimensions, storer);
+  store(video->thumbnail, storer);
+  store(file_id, storer);
+  if (video->has_stickers) {
+    store(video->sticker_file_ids, storer);
+  }
+}
+
+template <class T>
+FileId VideosManager::parse_video(T &parser) {
+  auto video = make_unique<Video>();
+  BEGIN_PARSE_FLAGS();
+  PARSE_FLAG(video->has_stickers);
+  PARSE_FLAG(video->supports_streaming);
+  END_PARSE_FLAGS();
+  parse(video->file_name, parser);
+  parse(video->mime_type, parser);
+  parse(video->duration, parser);
+  parse(video->dimensions, parser);
+  parse(video->thumbnail, parser);
+  parse(video->file_id, parser);
+  if (video->has_stickers) {
+    parse(video->sticker_file_ids, parser);
+  }
+  return on_get_video(std::move(video), true);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/VoiceNotesManager.cpp b/libs/tdlib/td/td/telegram/VoiceNotesManager.cpp
new file mode 100644
index 0000000000..0ba7b92291
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/VoiceNotesManager.cpp
@@ -0,0 +1,206 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/VoiceNotesManager.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/DocumentsManager.h"
+#include "td/telegram/files/FileManager.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/Td.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+VoiceNotesManager::VoiceNotesManager(Td *td) : td_(td) {
+}
+
+int32 VoiceNotesManager::get_voice_note_duration(FileId file_id) {
+  auto &voice_note = voice_notes_[file_id];
+  CHECK(voice_note != nullptr);
+  return voice_note->duration;
+}
+
+tl_object_ptr<td_api::voiceNote> VoiceNotesManager::get_voice_note_object(FileId file_id) {
+  if (!file_id.is_valid()) {
+    return nullptr;
+  }
+
+  auto &voice_note = voice_notes_[file_id];
+  CHECK(voice_note != nullptr);
+  voice_note->is_changed = false;
+  return make_tl_object<td_api::voiceNote>(voice_note->duration, voice_note->waveform, voice_note->mime_type,
+                                           td_->file_manager_->get_file_object(file_id));
+}
+
+FileId VoiceNotesManager::on_get_voice_note(std::unique_ptr<VoiceNote> new_voice_note, bool replace) {
+  auto file_id = new_voice_note->file_id;
+  LOG(INFO) << "Receive voice note " << file_id;
+  auto &v = voice_notes_[file_id];
+  if (v == nullptr) {
+    v = std::move(new_voice_note);
+  } else if (replace) {
+    CHECK(v->file_id == new_voice_note->file_id);
+    if (v->mime_type != new_voice_note->mime_type) {
+      LOG(DEBUG) << "Voice note " << file_id << " info has changed";
+      v->mime_type = new_voice_note->mime_type;
+      v->is_changed = true;
+    }
+    if (v->duration != new_voice_note->duration || v->waveform != new_voice_note->waveform) {
+      LOG(DEBUG) << "Voice note " << file_id << " info has changed";
+      v->duration = new_voice_note->duration;
+      v->waveform = new_voice_note->waveform;
+      v->is_changed = true;
+    }
+  }
+
+  return file_id;
+}
+
+const VoiceNotesManager::VoiceNote *VoiceNotesManager::get_voice_note(FileId file_id) const {
+  auto voice_note = voice_notes_.find(file_id);
+  if (voice_note == voice_notes_.end()) {
+    return nullptr;
+  }
+
+  CHECK(voice_note->second->file_id == file_id);
+  return voice_note->second.get();
+}
+
+FileId VoiceNotesManager::dup_voice_note(FileId new_id, FileId old_id) {
+  const VoiceNote *old_voice_note = get_voice_note(old_id);
+  CHECK(old_voice_note != nullptr);
+  auto &new_voice_note = voice_notes_[new_id];
+  CHECK(!new_voice_note);
+  new_voice_note = std::make_unique<VoiceNote>(*old_voice_note);
+  new_voice_note->file_id = new_id;
+  return new_id;
+}
+
+bool VoiceNotesManager::merge_voice_notes(FileId new_id, FileId old_id, bool can_delete_old) {
+  if (!old_id.is_valid()) {
+    LOG(ERROR) << "Old file id is invalid";
+    return true;
+  }
+
+  LOG(INFO) << "Merge voice notes " << new_id << " and " << old_id;
+  const VoiceNote *old_ = get_voice_note(old_id);
+  CHECK(old_ != nullptr);
+  if (old_id == new_id) {
+    return old_->is_changed;
+  }
+
+  auto new_it = voice_notes_.find(new_id);
+  if (new_it == voice_notes_.end()) {
+    auto &old = voice_notes_[old_id];
+    old->is_changed = true;
+    if (!can_delete_old) {
+      dup_voice_note(new_id, old_id);
+    } else {
+      old->file_id = new_id;
+      voice_notes_.emplace(new_id, std::move(old));
+    }
+  } else {
+    VoiceNote *new_ = new_it->second.get();
+    CHECK(new_ != nullptr);
+
+    if (!old_->mime_type.empty() && old_->mime_type != new_->mime_type) {
+      LOG(INFO) << "Voice note has changed: mime_type = (" << old_->mime_type << ", " << new_->mime_type << ")";
+    }
+
+    new_->is_changed = true;
+  }
+  LOG_STATUS(td_->file_manager_->merge(new_id, old_id));
+  if (can_delete_old) {
+    voice_notes_.erase(old_id);
+  }
+  return true;
+}
+
+void VoiceNotesManager::create_voice_note(FileId file_id, string mime_type, int32 duration, string waveform,
+                                          bool replace) {
+  auto v = std::make_unique<VoiceNote>();
+  v->file_id = file_id;
+  v->mime_type = std::move(mime_type);
+  v->duration = max(duration, 0);
+  v->waveform = std::move(waveform);
+  on_get_voice_note(std::move(v), replace);
+}
+
+SecretInputMedia VoiceNotesManager::get_secret_input_media(FileId voice_file_id,
+                                                           tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                                           const string &caption) const {
+  auto *voice_note = get_voice_note(voice_file_id);
+  CHECK(voice_note != nullptr);
+  auto file_view = td_->file_manager_->get_file_view(voice_file_id);
+  auto &encryption_key = file_view.encryption_key();
+  if (encryption_key.empty()) {
+    return SecretInputMedia{};
+  }
+  if (file_view.has_remote_location()) {
+    input_file = file_view.remote_location().as_input_encrypted_file();
+  }
+  if (!input_file) {
+    return SecretInputMedia{};
+  }
+  vector<tl_object_ptr<secret_api::DocumentAttribute>> attributes;
+  attributes.push_back(make_tl_object<secret_api::documentAttributeAudio>(
+      secret_api::documentAttributeAudio::Flags::VOICE_MASK | secret_api::documentAttributeAudio::Flags::WAVEFORM_MASK,
+      false /*ignored*/, voice_note->duration, "", "", BufferSlice(voice_note->waveform)));
+  return SecretInputMedia{std::move(input_file),
+                          make_tl_object<secret_api::decryptedMessageMediaDocument>(
+                              BufferSlice(), 0, 0, voice_note->mime_type, narrow_cast<int32>(file_view.size()),
+                              BufferSlice(encryption_key.key_slice()), BufferSlice(encryption_key.iv_slice()),
+                              std::move(attributes), caption)};
+}
+
+tl_object_ptr<telegram_api::InputMedia> VoiceNotesManager::get_input_media(
+    FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) const {
+  auto file_view = td_->file_manager_->get_file_view(file_id);
+  if (file_view.is_encrypted()) {
+    return nullptr;
+  }
+  if (file_view.has_remote_location() && !file_view.remote_location().is_web()) {
+    return make_tl_object<telegram_api::inputMediaDocument>(0, file_view.remote_location().as_input_document(), 0);
+  }
+  if (file_view.has_url()) {
+    return make_tl_object<telegram_api::inputMediaDocumentExternal>(0, file_view.url(), 0);
+  }
+  CHECK(!file_view.has_remote_location());
+
+  if (input_file != nullptr) {
+    const VoiceNote *voice_note = get_voice_note(file_id);
+    CHECK(voice_note != nullptr);
+
+    vector<tl_object_ptr<telegram_api::DocumentAttribute>> attributes;
+    int32 flags = telegram_api::documentAttributeAudio::VOICE_MASK;
+    if (!voice_note->waveform.empty()) {
+      flags |= telegram_api::documentAttributeAudio::WAVEFORM_MASK;
+    }
+    attributes.push_back(make_tl_object<telegram_api::documentAttributeAudio>(
+        flags, false /*ignored*/, voice_note->duration, "", "", BufferSlice(voice_note->waveform)));
+    string mime_type = voice_note->mime_type;
+    if (mime_type != "audio/ogg" && mime_type != "audio/mpeg" && mime_type != "audio/mp4") {
+      mime_type = "audio/ogg";
+    }
+    return make_tl_object<telegram_api::inputMediaUploadedDocument>(
+        0, false /*ignored*/, std::move(input_file), nullptr, mime_type, std::move(attributes),
+        vector<tl_object_ptr<telegram_api::InputDocument>>(), 0);
+  }
+
+  return nullptr;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/VoiceNotesManager.h b/libs/tdlib/td/td/telegram/VoiceNotesManager.h
new file mode 100644
index 0000000000..ba77f003ea
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/VoiceNotesManager.h
@@ -0,0 +1,72 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/files/FileId.h"
+#include "td/telegram/SecretInputMedia.h"
+
+#include "td/utils/common.h"
+
+#include <unordered_map>
+
+namespace td {
+class Td;
+}  // namespace td
+
+namespace td {
+
+class VoiceNotesManager {
+ public:
+  explicit VoiceNotesManager(Td *td);
+
+  int32 get_voice_note_duration(FileId file_id);
+
+  tl_object_ptr<td_api::voiceNote> get_voice_note_object(FileId file_id);
+
+  void create_voice_note(FileId file_id, string mime_type, int32 duration, string waveform, bool replace);
+
+  tl_object_ptr<telegram_api::InputMedia> get_input_media(FileId file_id,
+                                                          tl_object_ptr<telegram_api::InputFile> input_file) const;
+
+  SecretInputMedia get_secret_input_media(FileId voice_file_id,
+                                          tl_object_ptr<telegram_api::InputEncryptedFile> input_file,
+                                          const string &caption) const;
+
+  FileId dup_voice_note(FileId new_id, FileId old_id);
+
+  bool merge_voice_notes(FileId new_id, FileId old_id, bool can_delete_old);
+
+  template <class T>
+  void store_voice_note(FileId file_id, T &storer) const;
+
+  template <class T>
+  FileId parse_voice_note(T &parser);
+
+ private:
+  class VoiceNote {
+   public:
+    string mime_type;
+    int32 duration = 0;
+    string waveform;
+
+    FileId file_id;
+
+    bool is_changed = true;
+  };
+
+  const VoiceNote *get_voice_note(FileId file_id) const;
+
+  FileId on_get_voice_note(std::unique_ptr<VoiceNote> new_voice_note, bool replace);
+
+  Td *td_;
+  std::unordered_map<FileId, unique_ptr<VoiceNote>, FileIdHash> voice_notes_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/VoiceNotesManager.hpp b/libs/tdlib/td/td/telegram/VoiceNotesManager.hpp
new file mode 100644
index 0000000000..6165f42607
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/VoiceNotesManager.hpp
@@ -0,0 +1,39 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/VoiceNotesManager.h"
+
+#include "td/telegram/files/FileId.hpp"
+
+#include "td/utils/logging.h"
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+
+template <class T>
+void VoiceNotesManager::store_voice_note(FileId file_id, T &storer) const {
+  auto it = voice_notes_.find(file_id);
+  CHECK(it != voice_notes_.end());
+  const VoiceNote *voice_note = it->second.get();
+  store(voice_note->mime_type, storer);
+  store(voice_note->duration, storer);
+  store(voice_note->waveform, storer);
+  store(file_id, storer);
+}
+
+template <class T>
+FileId VoiceNotesManager::parse_voice_note(T &parser) {
+  auto voice_note = make_unique<VoiceNote>();
+  parse(voice_note->mime_type, parser);
+  parse(voice_note->duration, parser);
+  parse(voice_note->waveform, parser);
+  parse(voice_note->file_id, parser);
+  return on_get_voice_note(std::move(voice_note), true);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/WebPageId.h b/libs/tdlib/td/td/telegram/WebPageId.h
new file mode 100644
index 0000000000..bb05f57931
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/WebPageId.h
@@ -0,0 +1,66 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tl_helpers.h"
+
+#include <functional>
+#include <type_traits>
+
+namespace td {
+
+class WebPageId {
+  int64 id = 0;
+
+ public:
+  WebPageId() = default;
+
+  explicit WebPageId(int64 webpage_id) : id(webpage_id) {
+  }
+  template <class T, typename = std::enable_if_t<std::is_convertible<T, int64>::value>>
+  WebPageId(T webpage_id) = delete;
+
+  int64 get() const {
+    return id;
+  }
+
+  bool operator==(const WebPageId &other) const {
+    return id == other.id;
+  }
+
+  bool operator!=(const WebPageId &other) const {
+    return id != other.id;
+  }
+
+  bool is_valid() const {
+    return id != 0;
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(id, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(id, parser);
+  }
+};
+
+struct WebPageIdHash {
+  std::size_t operator()(WebPageId webpage_id) const {
+    return std::hash<int64>()(webpage_id.get());
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &string_builder, WebPageId webpage_id) {
+  return string_builder << "web page " << webpage_id.get();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/WebPagesManager.cpp b/libs/tdlib/td/td/telegram/WebPagesManager.cpp
new file mode 100644
index 0000000000..4e0157e369
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/WebPagesManager.cpp
@@ -0,0 +1,2775 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/WebPagesManager.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/telegram_api.hpp"
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/db/binlog/BinlogHelper.h"
+
+#include "td/telegram/AnimationsManager.h"
+#include "td/telegram/AnimationsManager.hpp"
+#include "td/telegram/AudiosManager.h"
+#include "td/telegram/AudiosManager.hpp"
+#include "td/telegram/ChannelId.h"
+#include "td/telegram/ContactsManager.h"
+#include "td/telegram/DocumentsManager.h"
+#include "td/telegram/DocumentsManager.hpp"
+#include "td/telegram/files/FileManager.h"
+#include "td/telegram/files/FileManager.hpp"
+#include "td/telegram/Global.h"
+#include "td/telegram/logevent/LogEvent.h"
+#include "td/telegram/MessageEntity.h"
+#include "td/telegram/MessagesManager.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/Photo.hpp"
+#include "td/telegram/StickersManager.h"
+#include "td/telegram/StickersManager.hpp"
+#include "td/telegram/Td.h"
+#include "td/telegram/VideoNotesManager.h"
+#include "td/telegram/VideoNotesManager.hpp"
+#include "td/telegram/VideosManager.h"
+#include "td/telegram/VideosManager.hpp"
+#include "td/telegram/VoiceNotesManager.h"
+#include "td/telegram/VoiceNotesManager.hpp"
+
+#include "td/utils/buffer.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tl_helpers.h"
+
+#include <type_traits>
+
+namespace td {
+
+class GetWebPagePreviewQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  int64 request_id_;
+  string url_;
+
+ public:
+  explicit GetWebPagePreviewQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(const string &text, vector<tl_object_ptr<telegram_api::MessageEntity>> &&entities, int64 request_id,
+            string url) {
+    request_id_ = request_id;
+    url_ = std::move(url);
+
+    int32 flags = 0;
+    if (!entities.empty()) {
+      flags |= telegram_api::messages_getWebPagePreview::ENTITIES_MASK;
+    }
+
+    send_query(G()->net_query_creator().create(
+        create_storer(telegram_api::messages_getWebPagePreview(flags, text, std::move(entities)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getWebPagePreview>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for GetWebPagePreviewQuery " << to_string(ptr);
+    td->web_pages_manager_->on_get_web_page_preview_success(request_id_, url_, std::move(ptr), std::move(promise_));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    td->web_pages_manager_->on_get_web_page_preview_fail(request_id_, url_, std::move(status), std::move(promise_));
+  }
+};
+
+class GetWebPageQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+  string url_;
+
+ public:
+  explicit GetWebPageQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(const string &url, int32 hash) {
+    url_ = url;
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::messages_getWebPage(url, hash))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::messages_getWebPage>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto ptr = result_ptr.move_as_ok();
+    LOG(INFO) << "Receive result for GetWebPageQuery " << to_string(ptr);
+    if (ptr->get_id() != telegram_api::webPageNotModified::ID) {
+      auto web_page_id = td->web_pages_manager_->on_get_web_page(std::move(ptr), DialogId());
+      td->web_pages_manager_->on_get_web_page_by_url(url_, web_page_id, false);
+    }
+
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class WebPagesManager::WebPageInstantView {
+ public:
+  vector<unique_ptr<PageBlock>> page_blocks;
+  int32 hash = 0;
+  bool is_empty = true;
+  bool is_full = false;
+  bool is_loaded = false;
+  bool was_loaded_from_database = false;
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    BEGIN_STORE_FLAGS();
+    STORE_FLAG(is_full);
+    STORE_FLAG(is_loaded);
+    END_STORE_FLAGS();
+
+    store(page_blocks, storer);
+    store(hash, storer);
+    CHECK(!is_empty);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    BEGIN_PARSE_FLAGS();
+    PARSE_FLAG(is_full);
+    PARSE_FLAG(is_loaded);
+    END_PARSE_FLAGS();
+
+    parse(page_blocks, parser);
+    parse(hash, parser);
+    is_empty = false;
+  }
+
+  friend StringBuilder &operator<<(StringBuilder &string_builder,
+                                   const WebPagesManager::WebPageInstantView &instant_view) {
+    return string_builder << "InstantView(size = " << instant_view.page_blocks.size()
+                          << ", hash = " << instant_view.hash << ", is_empty = " << instant_view.is_empty
+                          << ", is_full = " << instant_view.is_full << ", is_loaded = " << instant_view.is_loaded
+                          << ", was_loaded_from_database = " << instant_view.was_loaded_from_database << ")";
+  }
+};
+
+class WebPagesManager::WebPage {
+ public:
+  string url;
+  string display_url;
+  string type;
+  string site_name;
+  string title;
+  string description;
+  Photo photo;
+  string embed_url;
+  string embed_type;
+  Dimensions embed_dimensions;
+  int32 duration = 0;
+  string author;
+  DocumentsManager::DocumentType document_type = DocumentsManager::DocumentType::Unknown;
+  FileId document_file_id;
+  WebPageInstantView instant_view;
+
+  uint64 logevent_id = 0;
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    bool has_type = !type.empty();
+    bool has_site_name = !site_name.empty();
+    bool has_title = !title.empty();
+    bool has_description = !description.empty();
+    bool has_photo = photo.id != -2;
+    bool has_embed = !embed_url.empty();
+    bool has_embed_dimensions = has_embed && embed_dimensions != Dimensions();
+    bool has_duration = duration > 0;
+    bool has_author = !author.empty();
+    bool has_document = document_type != DocumentsManager::DocumentType::Unknown;
+    bool has_instant_view = !instant_view.is_empty;
+    bool has_no_hash = true;
+    BEGIN_STORE_FLAGS();
+    STORE_FLAG(has_type);
+    STORE_FLAG(has_site_name);
+    STORE_FLAG(has_title);
+    STORE_FLAG(has_description);
+    STORE_FLAG(has_photo);
+    STORE_FLAG(has_embed);
+    STORE_FLAG(has_embed_dimensions);
+    STORE_FLAG(has_duration);
+    STORE_FLAG(has_author);
+    STORE_FLAG(has_document);
+    STORE_FLAG(has_instant_view);
+    STORE_FLAG(has_no_hash);
+    END_STORE_FLAGS();
+
+    store(url, storer);
+    store(display_url, storer);
+    if (has_type) {
+      store(type, storer);
+    }
+    if (has_site_name) {
+      store(site_name, storer);
+    }
+    if (has_title) {
+      store(title, storer);
+    }
+    if (has_description) {
+      store(description, storer);
+    }
+    if (has_photo) {
+      store(photo, storer);
+    }
+    if (has_embed) {
+      store(embed_url, storer);
+      store(embed_type, storer);
+    }
+    if (has_embed_dimensions) {
+      store(embed_dimensions, storer);
+    }
+    if (has_duration) {
+      store(duration, storer);
+    }
+    if (has_author) {
+      store(author, storer);
+    }
+    if (has_document) {
+      Td *td = storer.context()->td().get_actor_unsafe();
+      CHECK(td != nullptr);
+
+      store(document_type, storer);
+      switch (document_type) {
+        case DocumentsManager::DocumentType::Animation:
+          td->animations_manager_->store_animation(document_file_id, storer);
+          break;
+        case DocumentsManager::DocumentType::Audio:
+          td->audios_manager_->store_audio(document_file_id, storer);
+          break;
+        case DocumentsManager::DocumentType::General:
+          td->documents_manager_->store_document(document_file_id, storer);
+          break;
+        case DocumentsManager::DocumentType::Sticker:
+          td->stickers_manager_->store_sticker(document_file_id, false, storer);
+          break;
+        case DocumentsManager::DocumentType::Video:
+          td->videos_manager_->store_video(document_file_id, storer);
+          break;
+        case DocumentsManager::DocumentType::VideoNote:
+          td->video_notes_manager_->store_video_note(document_file_id, storer);
+          break;
+        case DocumentsManager::DocumentType::VoiceNote:
+          td->voice_notes_manager_->store_voice_note(document_file_id, storer);
+          break;
+        case DocumentsManager::DocumentType::Unknown:
+        default:
+          UNREACHABLE();
+      }
+    }
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    bool has_type;
+    bool has_site_name;
+    bool has_title;
+    bool has_description;
+    bool has_photo;
+    bool has_embed;
+    bool has_embed_dimensions;
+    bool has_duration;
+    bool has_author;
+    bool has_document;
+    bool has_instant_view;
+    bool has_no_hash;
+    BEGIN_PARSE_FLAGS();
+    PARSE_FLAG(has_type);
+    PARSE_FLAG(has_site_name);
+    PARSE_FLAG(has_title);
+    PARSE_FLAG(has_description);
+    PARSE_FLAG(has_photo);
+    PARSE_FLAG(has_embed);
+    PARSE_FLAG(has_embed_dimensions);
+    PARSE_FLAG(has_duration);
+    PARSE_FLAG(has_author);
+    PARSE_FLAG(has_document);
+    PARSE_FLAG(has_instant_view);
+    PARSE_FLAG(has_no_hash);
+    END_PARSE_FLAGS();
+
+    parse(url, parser);
+    parse(display_url, parser);
+    if (!has_no_hash) {
+      int32 hash;
+      parse(hash, parser);
+    }
+    if (has_type) {
+      parse(type, parser);
+    }
+    if (has_site_name) {
+      parse(site_name, parser);
+    }
+    if (has_title) {
+      parse(title, parser);
+    }
+    if (has_description) {
+      parse(description, parser);
+    }
+    if (has_photo) {
+      parse(photo, parser);
+    } else {
+      photo.id = -2;
+    }
+    if (has_embed) {
+      parse(embed_url, parser);
+      parse(embed_type, parser);
+    }
+    if (has_embed_dimensions) {
+      parse(embed_dimensions, parser);
+    }
+    if (has_duration) {
+      parse(duration, parser);
+    }
+    if (has_author) {
+      parse(author, parser);
+    }
+    if (has_document) {
+      Td *td = parser.context()->td().get_actor_unsafe();
+      CHECK(td != nullptr);
+
+      parse(document_type, parser);
+      switch (document_type) {
+        case DocumentsManager::DocumentType::Animation:
+          document_file_id = td->animations_manager_->parse_animation(parser);
+          break;
+        case DocumentsManager::DocumentType::Audio:
+          document_file_id = td->audios_manager_->parse_audio(parser);
+          break;
+        case DocumentsManager::DocumentType::General:
+          document_file_id = td->documents_manager_->parse_document(parser);
+          break;
+        case DocumentsManager::DocumentType::Sticker:
+          document_file_id = td->stickers_manager_->parse_sticker(false, parser);
+          break;
+        case DocumentsManager::DocumentType::Video:
+          document_file_id = td->videos_manager_->parse_video(parser);
+          break;
+        case DocumentsManager::DocumentType::VideoNote:
+          document_file_id = td->video_notes_manager_->parse_video_note(parser);
+          break;
+        case DocumentsManager::DocumentType::VoiceNote:
+          document_file_id = td->voice_notes_manager_->parse_voice_note(parser);
+          break;
+        case DocumentsManager::DocumentType::Unknown:
+        default:
+          UNREACHABLE();
+      }
+      if (!document_file_id.is_valid()) {
+        LOG(ERROR) << "Parse invalid document_file_id";
+        document_type = DocumentsManager::DocumentType::Unknown;
+      }
+    }
+
+    if (has_instant_view) {
+      instant_view.is_empty = false;
+    }
+  }
+};
+
+class WebPagesManager::RichText {
+ public:
+  enum class Type : int32 { Plain, Bold, Italic, Underline, Strikethrough, Fixed, Url, EmailAddress, Concatenation };
+  Type type = Type::Plain;
+  string content;
+  vector<RichText> texts;
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(type, storer);
+    store(content, storer);
+    store(texts, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(type, parser);
+    parse(content, parser);
+    parse(texts, parser);
+  }
+};
+
+class WebPagesManager::PageBlock {
+ public:
+  enum class Type : int32 {
+    Title,
+    Subtitle,
+    AuthorDate,
+    Header,
+    Subheader,
+    Paragraph,
+    Preformatted,
+    Footer,
+    Divider,
+    Anchor,
+    List,
+    BlockQuote,
+    PullQuote,
+    Animation,
+    Photo,
+    Video,
+    Cover,
+    Embedded,
+    EmbeddedPost,
+    Collage,
+    Slideshow,
+    ChatLink,
+    Audio
+  };
+
+  virtual Type get_type() const = 0;
+
+  virtual tl_object_ptr<td_api::PageBlock> get_page_block_object() const = 0;
+
+  PageBlock() = default;
+  PageBlock(const PageBlock &) = delete;
+  PageBlock &operator=(const PageBlock &) = delete;
+  PageBlock(PageBlock &&) = delete;
+  PageBlock &operator=(PageBlock &&) = delete;
+  virtual ~PageBlock() = default;
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    Type type = get_type();
+    store(type, storer);
+    call_impl(type, this, [&](const auto *object) { store(*object, storer); });
+  }
+  template <class T>
+  static std::unique_ptr<PageBlock> parse(T &parser) {
+    using ::td::parse;
+    Type type;
+    parse(type, parser);
+    std::unique_ptr<PageBlock> res;
+    call_impl(type, nullptr, [&](const auto *ptr) {
+      using ObjT = std::decay_t<decltype(*ptr)>;
+      auto object = std::make_unique<ObjT>();
+      parse(*object, parser);
+      res = std::move(object);
+    });
+    return res;
+  }
+
+ private:
+  template <class F>
+  static void call_impl(Type type, const PageBlock *ptr, F &&f);
+};
+
+template <class T>
+void store(const unique_ptr<WebPagesManager::PageBlock> &block, T &storer) {
+  block->store(storer);
+}
+
+template <class T>
+void parse(unique_ptr<WebPagesManager::PageBlock> &block, T &parser) {
+  block = WebPagesManager::PageBlock::parse(parser);
+}
+
+class WebPagesManager::PageBlockTitle : public PageBlock {
+  RichText title;
+
+ public:
+  PageBlockTitle() = default;
+
+  explicit PageBlockTitle(RichText &&title) : title(std::move(title)) {
+  }
+
+  Type get_type() const override {
+    return Type::Title;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockTitle>(get_rich_text_object(title));
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(title, storer);
+  }
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(title, parser);
+  }
+};
+
+class WebPagesManager::PageBlockSubtitle : public PageBlock {
+  RichText subtitle;
+
+ public:
+  PageBlockSubtitle() = default;
+  explicit PageBlockSubtitle(RichText &&subtitle) : subtitle(std::move(subtitle)) {
+  }
+
+  Type get_type() const override {
+    return Type::Subtitle;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockSubtitle>(get_rich_text_object(subtitle));
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(subtitle, storer);
+  }
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(subtitle, parser);
+  }
+};
+
+class WebPagesManager::PageBlockAuthorDate : public PageBlock {
+  RichText author;
+  int32 date = 0;
+
+ public:
+  PageBlockAuthorDate() = default;
+  PageBlockAuthorDate(RichText &&author, int32 date) : author(std::move(author)), date(max(date, 0)) {
+  }
+
+  Type get_type() const override {
+    return Type::AuthorDate;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockAuthorDate>(get_rich_text_object(author), date);
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(author, storer);
+    store(date, storer);
+  }
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(author, parser);
+    parse(date, parser);
+  }
+};
+
+class WebPagesManager::PageBlockHeader : public PageBlock {
+  RichText header;
+
+ public:
+  PageBlockHeader() = default;
+  explicit PageBlockHeader(RichText &&header) : header(std::move(header)) {
+  }
+
+  Type get_type() const override {
+    return Type::Header;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockHeader>(get_rich_text_object(header));
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(header, storer);
+  }
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(header, parser);
+  }
+};
+
+class WebPagesManager::PageBlockSubheader : public PageBlock {
+  RichText subheader;
+
+ public:
+  PageBlockSubheader() = default;
+  explicit PageBlockSubheader(RichText &&subheader) : subheader(std::move(subheader)) {
+  }
+
+  Type get_type() const override {
+    return Type::Subheader;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockSubheader>(get_rich_text_object(subheader));
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(subheader, storer);
+  }
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(subheader, parser);
+  }
+};
+
+class WebPagesManager::PageBlockParagraph : public PageBlock {
+  RichText text;
+
+ public:
+  PageBlockParagraph() = default;
+  explicit PageBlockParagraph(RichText &&text) : text(std::move(text)) {
+  }
+
+  Type get_type() const override {
+    return Type::Paragraph;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockParagraph>(get_rich_text_object(text));
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(text, storer);
+  }
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(text, parser);
+  }
+};
+
+class WebPagesManager::PageBlockPreformatted : public PageBlock {
+  RichText text;
+  string language;
+
+ public:
+  PageBlockPreformatted() = default;
+  PageBlockPreformatted(RichText &&text, string language) : text(std::move(text)), language(std::move(language)) {
+  }
+
+  Type get_type() const override {
+    return Type::Preformatted;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockPreformatted>(get_rich_text_object(text), language);
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(text, storer);
+    store(language, storer);
+  }
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(text, parser);
+    parse(language, parser);
+  }
+};
+
+class WebPagesManager::PageBlockFooter : public PageBlock {
+  RichText footer;
+
+ public:
+  PageBlockFooter() = default;
+  explicit PageBlockFooter(RichText &&footer) : footer(std::move(footer)) {
+  }
+
+  Type get_type() const override {
+    return Type::Footer;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockFooter>(get_rich_text_object(footer));
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(footer, storer);
+  }
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(footer, parser);
+  }
+};
+
+class WebPagesManager::PageBlockDivider : public PageBlock {
+ public:
+  Type get_type() const override {
+    return Type::Divider;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockDivider>();
+  }
+  template <class T>
+  void store(T &storer) const {
+  }
+  template <class T>
+  void parse(T &parser) {
+  }
+};
+
+class WebPagesManager::PageBlockAnchor : public PageBlock {
+  string name;
+
+ public:
+  PageBlockAnchor() = default;
+  explicit PageBlockAnchor(string name) : name(std::move(name)) {
+  }
+
+  Type get_type() const override {
+    return Type::Anchor;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockAnchor>(name);
+  }
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(name, storer);
+  }
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(name, parser);
+  }
+};
+
+class WebPagesManager::PageBlockList : public PageBlock {
+  vector<RichText> items;
+  bool is_ordered = false;
+
+ public:
+  PageBlockList() = default;
+  PageBlockList(vector<RichText> &&items, bool is_ordered) : items(std::move(items)), is_ordered(is_ordered) {
+  }
+
+  Type get_type() const override {
+    return Type::List;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockList>(get_rich_text_objects(items), is_ordered);
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+
+    BEGIN_STORE_FLAGS();
+    STORE_FLAG(is_ordered);
+    END_STORE_FLAGS();
+
+    store(items, storer);
+  }
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+
+    BEGIN_PARSE_FLAGS();
+    PARSE_FLAG(is_ordered);
+    END_PARSE_FLAGS();
+
+    parse(items, parser);
+  }
+};
+
+class WebPagesManager::PageBlockBlockQuote : public PageBlock {
+  RichText text;
+  RichText caption;
+
+ public:
+  PageBlockBlockQuote() = default;
+  PageBlockBlockQuote(RichText &&text, RichText &&caption) : text(std::move(text)), caption(std::move(caption)) {
+  }
+
+  Type get_type() const override {
+    return Type::BlockQuote;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockBlockQuote>(get_rich_text_object(text), get_rich_text_object(caption));
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(text, storer);
+    store(caption, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(text, parser);
+    parse(caption, parser);
+  }
+};
+
+class WebPagesManager::PageBlockPullQuote : public PageBlock {
+  RichText text;
+  RichText caption;
+
+ public:
+  PageBlockPullQuote() = default;
+  PageBlockPullQuote(RichText &&text, RichText &&caption) : text(std::move(text)), caption(std::move(caption)) {
+  }
+
+  Type get_type() const override {
+    return Type::PullQuote;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockPullQuote>(get_rich_text_object(text), get_rich_text_object(caption));
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(text, storer);
+    store(caption, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(text, parser);
+    parse(caption, parser);
+  }
+};
+
+class WebPagesManager::PageBlockAnimation : public PageBlock {
+  FileId animation_file_id;
+  RichText caption;
+  bool need_autoplay = false;
+
+ public:
+  PageBlockAnimation() = default;
+  PageBlockAnimation(FileId animation_file_id, RichText &&caption, bool need_autoplay)
+      : animation_file_id(animation_file_id), caption(std::move(caption)), need_autoplay(need_autoplay) {
+  }
+
+  Type get_type() const override {
+    return Type::Animation;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockAnimation>(
+        G()->td().get_actor_unsafe()->animations_manager_->get_animation_object(animation_file_id,
+                                                                                "get_page_block_object"),
+        get_rich_text_object(caption), need_autoplay);
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+
+    bool has_empty_animation = !animation_file_id.is_valid();
+    BEGIN_STORE_FLAGS();
+    STORE_FLAG(need_autoplay);
+    STORE_FLAG(has_empty_animation);
+    END_STORE_FLAGS();
+
+    if (!has_empty_animation) {
+      storer.context()->td().get_actor_unsafe()->animations_manager_->store_animation(animation_file_id, storer);
+    }
+    store(caption, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+
+    bool has_empty_animation;
+    BEGIN_PARSE_FLAGS();
+    PARSE_FLAG(need_autoplay);
+    PARSE_FLAG(has_empty_animation);
+    END_PARSE_FLAGS();
+
+    if (parser.version() >= static_cast<int32>(Version::FixWebPageInstantViewDatabase)) {
+      if (!has_empty_animation) {
+        animation_file_id = parser.context()->td().get_actor_unsafe()->animations_manager_->parse_animation(parser);
+      } else {
+        animation_file_id = FileId();
+      }
+    } else {
+      animation_file_id = FileId();
+      parser.set_error("Wrong stored object");
+    }
+    parse(caption, parser);
+  }
+};
+
+class WebPagesManager::PageBlockPhoto : public PageBlock {
+  Photo photo;
+  RichText caption;
+
+ public:
+  PageBlockPhoto() = default;
+  PageBlockPhoto(Photo photo, RichText &&caption) : photo(std::move(photo)), caption(std::move(caption)) {
+  }
+
+  Type get_type() const override {
+    return Type::Photo;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockPhoto>(
+        get_photo_object(G()->td().get_actor_unsafe()->file_manager_.get(), &photo), get_rich_text_object(caption));
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(photo, storer);
+    store(caption, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(photo, parser);
+    parse(caption, parser);
+  }
+};
+
+class WebPagesManager::PageBlockVideo : public PageBlock {
+  FileId video_file_id;
+  RichText caption;
+  bool need_autoplay = false;
+  bool is_looped = false;
+
+ public:
+  PageBlockVideo() = default;
+  PageBlockVideo(FileId video_file_id, RichText &&caption, bool need_autoplay, bool is_looped)
+      : video_file_id(video_file_id), caption(std::move(caption)), need_autoplay(need_autoplay), is_looped(is_looped) {
+  }
+
+  Type get_type() const override {
+    return Type::Video;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockVideo>(
+        G()->td().get_actor_unsafe()->videos_manager_->get_video_object(video_file_id), get_rich_text_object(caption),
+        need_autoplay, is_looped);
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+
+    bool has_empty_video = !video_file_id.is_valid();
+    BEGIN_STORE_FLAGS();
+    STORE_FLAG(need_autoplay);
+    STORE_FLAG(is_looped);
+    STORE_FLAG(has_empty_video);
+    END_STORE_FLAGS();
+
+    if (!has_empty_video) {
+      storer.context()->td().get_actor_unsafe()->videos_manager_->store_video(video_file_id, storer);
+    }
+    store(caption, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+
+    bool has_empty_video;
+    BEGIN_PARSE_FLAGS();
+    PARSE_FLAG(need_autoplay);
+    PARSE_FLAG(is_looped);
+    PARSE_FLAG(has_empty_video);
+    END_PARSE_FLAGS();
+
+    if (parser.version() >= static_cast<int32>(Version::FixWebPageInstantViewDatabase)) {
+      if (!has_empty_video) {
+        video_file_id = parser.context()->td().get_actor_unsafe()->videos_manager_->parse_video(parser);
+      } else {
+        video_file_id = FileId();
+      }
+    } else {
+      video_file_id = FileId();
+      parser.set_error("Wrong stored object");
+    }
+    parse(caption, parser);
+  }
+};
+
+class WebPagesManager::PageBlockCover : public PageBlock {
+  unique_ptr<PageBlock> cover;
+
+ public:
+  PageBlockCover() = default;
+  explicit PageBlockCover(unique_ptr<PageBlock> &&cover) : cover(std::move(cover)) {
+  }
+
+  Type get_type() const override {
+    return Type::Cover;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockCover>(cover->get_page_block_object());
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(cover, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(cover, parser);
+  }
+};
+
+class WebPagesManager::PageBlockEmbedded : public PageBlock {
+  string url;
+  string html;
+  Photo poster_photo;
+  Dimensions dimensions;
+  RichText caption;
+  bool is_full_width;
+  bool allow_scrolling;
+
+ public:
+  PageBlockEmbedded() = default;
+  PageBlockEmbedded(string url, string html, Photo poster_photo, Dimensions dimensions, RichText &&caption,
+                    bool is_full_width, bool allow_scrolling)
+      : url(std::move(url))
+      , html(std::move(html))
+      , poster_photo(std::move(poster_photo))
+      , dimensions(dimensions)
+      , caption(std::move(caption))
+      , is_full_width(is_full_width)
+      , allow_scrolling(allow_scrolling) {
+  }
+
+  Type get_type() const override {
+    return Type::Embedded;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockEmbedded>(
+        url, html, get_photo_object(G()->td().get_actor_unsafe()->file_manager_.get(), &poster_photo), dimensions.width,
+        dimensions.height, get_rich_text_object(caption), is_full_width, allow_scrolling);
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    BEGIN_STORE_FLAGS();
+    STORE_FLAG(is_full_width);
+    STORE_FLAG(allow_scrolling);
+    END_STORE_FLAGS();
+
+    store(url, storer);
+    store(html, storer);
+    store(poster_photo, storer);
+    store(dimensions, storer);
+    store(caption, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    BEGIN_PARSE_FLAGS();
+    PARSE_FLAG(is_full_width);
+    PARSE_FLAG(allow_scrolling);
+    END_PARSE_FLAGS();
+
+    parse(url, parser);
+    parse(html, parser);
+    parse(poster_photo, parser);
+    parse(dimensions, parser);
+    parse(caption, parser);
+  }
+};
+
+class WebPagesManager::PageBlockEmbeddedPost : public PageBlock {
+  string url;
+  string author;
+  Photo author_photo;
+  int32 date;
+  vector<unique_ptr<PageBlock>> page_blocks;
+  RichText caption;
+
+ public:
+  PageBlockEmbeddedPost() = default;
+  PageBlockEmbeddedPost(string url, string author, Photo author_photo, int32 date,
+                        vector<unique_ptr<PageBlock>> &&page_blocks, RichText &&caption)
+      : url(std::move(url))
+      , author(std::move(author))
+      , author_photo(std::move(author_photo))
+      , date(max(date, 0))
+      , page_blocks(std::move(page_blocks))
+      , caption(std::move(caption)) {
+  }
+
+  Type get_type() const override {
+    return Type::EmbeddedPost;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockEmbeddedPost>(
+        url, author, get_photo_object(G()->td().get_actor_unsafe()->file_manager_.get(), &author_photo), date,
+        get_page_block_objects(page_blocks), get_rich_text_object(caption));
+  }
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(url, storer);
+    store(author, storer);
+    store(author_photo, storer);
+    store(date, storer);
+    store(page_blocks, storer);
+    store(caption, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(url, parser);
+    parse(author, parser);
+    parse(author_photo, parser);
+    parse(date, parser);
+    parse(page_blocks, parser);
+    parse(caption, parser);
+  }
+};
+
+class WebPagesManager::PageBlockCollage : public PageBlock {
+  vector<unique_ptr<PageBlock>> page_blocks;
+  RichText caption;
+
+ public:
+  PageBlockCollage() = default;
+  PageBlockCollage(vector<unique_ptr<PageBlock>> &&page_blocks, RichText &&caption)
+      : page_blocks(std::move(page_blocks)), caption(std::move(caption)) {
+  }
+
+  Type get_type() const override {
+    return Type::Collage;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockCollage>(get_page_block_objects(page_blocks), get_rich_text_object(caption));
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(page_blocks, storer);
+    store(caption, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(page_blocks, parser);
+    parse(caption, parser);
+  }
+};
+
+class WebPagesManager::PageBlockSlideshow : public PageBlock {
+  vector<unique_ptr<PageBlock>> page_blocks;
+  RichText caption;
+
+ public:
+  PageBlockSlideshow() = default;
+  PageBlockSlideshow(vector<unique_ptr<PageBlock>> &&page_blocks, RichText &&caption)
+      : page_blocks(std::move(page_blocks)), caption(std::move(caption)) {
+  }
+
+  Type get_type() const override {
+    return Type::Slideshow;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockSlideshow>(get_page_block_objects(page_blocks),
+                                                      get_rich_text_object(caption));
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(page_blocks, storer);
+    store(caption, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(page_blocks, parser);
+    parse(caption, parser);
+  }
+};
+
+class WebPagesManager::PageBlockChatLink : public PageBlock {
+  string title;
+  DialogPhoto photo;
+  string username;
+
+ public:
+  PageBlockChatLink() = default;
+  PageBlockChatLink(string title, DialogPhoto photo, string username)
+      : title(std::move(title)), photo(std::move(photo)), username(std::move(username)) {
+  }
+
+  Type get_type() const override {
+    return Type::ChatLink;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockChatLink>(
+        title, get_chat_photo_object(G()->td().get_actor_unsafe()->file_manager_.get(), &photo), username);
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+    store(title, storer);
+    store(photo, storer);
+    store(username, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+    parse(title, parser);
+    parse(photo, parser);
+    parse(username, parser);
+  }
+};
+
+class WebPagesManager::PageBlockAudio : public PageBlock {
+  FileId audio_file_id;
+  RichText caption;
+
+ public:
+  PageBlockAudio() = default;
+  PageBlockAudio(FileId audio_file_id, RichText &&caption) : audio_file_id(audio_file_id), caption(std::move(caption)) {
+  }
+
+  Type get_type() const override {
+    return Type::Audio;
+  }
+
+  tl_object_ptr<td_api::PageBlock> get_page_block_object() const override {
+    return make_tl_object<td_api::pageBlockAudio>(
+        G()->td().get_actor_unsafe()->audios_manager_->get_audio_object(audio_file_id), get_rich_text_object(caption));
+  }
+
+  template <class T>
+  void store(T &storer) const {
+    using ::td::store;
+
+    bool has_empty_audio = !audio_file_id.is_valid();
+    BEGIN_STORE_FLAGS();
+    STORE_FLAG(has_empty_audio);
+    END_STORE_FLAGS();
+
+    if (!has_empty_audio) {
+      storer.context()->td().get_actor_unsafe()->audios_manager_->store_audio(audio_file_id, storer);
+    }
+    store(caption, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using ::td::parse;
+
+    bool has_empty_audio;
+    if (parser.version() >= static_cast<int32>(Version::FixPageBlockAudioEmptyFile)) {
+      BEGIN_PARSE_FLAGS();
+      PARSE_FLAG(has_empty_audio);
+      END_PARSE_FLAGS();
+    } else {
+      has_empty_audio = false;
+    }
+
+    if (!has_empty_audio) {
+      audio_file_id = parser.context()->td().get_actor_unsafe()->audios_manager_->parse_audio(parser);
+    } else {
+      audio_file_id = FileId();
+    }
+    parse(caption, parser);
+  }
+};
+
+template <class F>
+void WebPagesManager::PageBlock::call_impl(Type type, const PageBlock *ptr, F &&f) {
+  switch (type) {
+    case Type::Title:
+      return f(static_cast<const WebPagesManager::PageBlockTitle *>(ptr));
+    case Type::Subtitle:
+      return f(static_cast<const WebPagesManager::PageBlockSubtitle *>(ptr));
+    case Type::AuthorDate:
+      return f(static_cast<const WebPagesManager::PageBlockAuthorDate *>(ptr));
+    case Type::Header:
+      return f(static_cast<const WebPagesManager::PageBlockHeader *>(ptr));
+    case Type::Subheader:
+      return f(static_cast<const WebPagesManager::PageBlockSubheader *>(ptr));
+    case Type::Paragraph:
+      return f(static_cast<const WebPagesManager::PageBlockParagraph *>(ptr));
+    case Type::Preformatted:
+      return f(static_cast<const WebPagesManager::PageBlockPreformatted *>(ptr));
+    case Type::Footer:
+      return f(static_cast<const WebPagesManager::PageBlockFooter *>(ptr));
+    case Type::Divider:
+      return f(static_cast<const WebPagesManager::PageBlockDivider *>(ptr));
+    case Type::Anchor:
+      return f(static_cast<const WebPagesManager::PageBlockAnchor *>(ptr));
+    case Type::List:
+      return f(static_cast<const WebPagesManager::PageBlockList *>(ptr));
+    case Type::BlockQuote:
+      return f(static_cast<const WebPagesManager::PageBlockBlockQuote *>(ptr));
+    case Type::PullQuote:
+      return f(static_cast<const WebPagesManager::PageBlockPullQuote *>(ptr));
+    case Type::Animation:
+      return f(static_cast<const WebPagesManager::PageBlockAnimation *>(ptr));
+    case Type::Photo:
+      return f(static_cast<const WebPagesManager::PageBlockPhoto *>(ptr));
+    case Type::Video:
+      return f(static_cast<const WebPagesManager::PageBlockVideo *>(ptr));
+    case Type::Cover:
+      return f(static_cast<const WebPagesManager::PageBlockCover *>(ptr));
+    case Type::Embedded:
+      return f(static_cast<const WebPagesManager::PageBlockEmbedded *>(ptr));
+    case Type::EmbeddedPost:
+      return f(static_cast<const WebPagesManager::PageBlockEmbeddedPost *>(ptr));
+    case Type::Collage:
+      return f(static_cast<const WebPagesManager::PageBlockCollage *>(ptr));
+    case Type::Slideshow:
+      return f(static_cast<const WebPagesManager::PageBlockSlideshow *>(ptr));
+    case Type::ChatLink:
+      return f(static_cast<const WebPagesManager::PageBlockChatLink *>(ptr));
+    case Type::Audio:
+      return f(static_cast<const WebPagesManager::PageBlockAudio *>(ptr));
+  }
+  UNREACHABLE();
+}
+
+WebPagesManager::WebPagesManager(Td *td, ActorShared<> parent) : td_(td), parent_(std::move(parent)) {
+  pending_web_pages_timeout_.set_callback(on_pending_web_page_timeout_callback);
+  pending_web_pages_timeout_.set_callback_data(static_cast<void *>(this));
+}
+
+void WebPagesManager::tear_down() {
+  parent_.reset();
+}
+
+WebPagesManager::~WebPagesManager() = default;
+
+WebPageId WebPagesManager::on_get_web_page(tl_object_ptr<telegram_api::WebPage> &&web_page_ptr,
+                                           DialogId owner_dialog_id) {
+  CHECK(web_page_ptr != nullptr);
+  LOG(DEBUG) << "Got " << to_string(web_page_ptr);
+  switch (web_page_ptr->get_id()) {
+    case telegram_api::webPageEmpty::ID: {
+      auto web_page = move_tl_object_as<telegram_api::webPageEmpty>(web_page_ptr);
+      WebPageId web_page_id(web_page->id_);
+      if (!web_page_id.is_valid()) {
+        LOG_IF(ERROR, web_page_id != WebPageId()) << "Receive invalid " << web_page_id;
+        return WebPageId();
+      }
+
+      LOG(INFO) << "Got empty " << web_page_id;
+      auto web_page_to_delete = get_web_page(web_page_id);
+      if (web_page_to_delete != nullptr) {
+        if (web_page_to_delete->logevent_id != 0) {
+          LOG(INFO) << "Erase " << web_page_id << " from binlog";
+          BinlogHelper::erase(G()->td_db()->get_binlog(), web_page_to_delete->logevent_id);
+          web_page_to_delete->logevent_id = 0;
+        }
+        web_pages_.erase(web_page_id);
+      }
+
+      update_messages_content(web_page_id, false);
+      if (!G()->parameters().use_message_db) {
+        //        update_messages_content(web_page_id, false);
+      } else {
+        LOG(INFO) << "Delete " << web_page_id << " from database";
+        G()->td_db()->get_sqlite_pmc()->erase(get_web_page_database_key(web_page_id), Auto()
+                                              /*
+              PromiseCreator::lambda([web_page_id](Result<> result) {
+                if (result.is_ok()) {
+                  send_closure(G()->web_pages_manager(), &WebPagesManager::update_messages_content, web_page_id, false);
+                }
+              })
+            */
+        );
+        G()->td_db()->get_sqlite_pmc()->erase(get_web_page_instant_view_database_key(web_page_id), Auto());
+      }
+
+      return WebPageId();
+    }
+    case telegram_api::webPagePending::ID: {
+      auto web_page = move_tl_object_as<telegram_api::webPagePending>(web_page_ptr);
+      WebPageId web_page_id(web_page->id_);
+      if (!web_page_id.is_valid()) {
+        LOG(ERROR) << "Receive invalid " << web_page_id;
+        return WebPageId();
+      }
+
+      auto web_page_date = web_page->date_;
+      LOG(INFO) << "Got pending " << web_page_id << ", date = " << web_page_date << ", now = " << G()->server_time();
+
+      pending_web_pages_timeout_.add_timeout_in(web_page_id.get(), max(web_page_date - G()->server_time(), 1.0));
+      return web_page_id;
+    }
+    case telegram_api::webPage::ID: {
+      auto web_page = move_tl_object_as<telegram_api::webPage>(web_page_ptr);
+      WebPageId web_page_id(web_page->id_);
+      if (!web_page_id.is_valid()) {
+        LOG(ERROR) << "Receive invalid " << web_page_id;
+        return WebPageId();
+      }
+
+      LOG(INFO) << "Got " << web_page_id;
+      auto page = make_unique<WebPage>();
+
+      page->url = std::move(web_page->url_);
+      page->display_url = std::move(web_page->display_url_);
+      page->type = std::move(web_page->type_);
+      page->site_name = std::move(web_page->site_name_);
+      page->title = std::move(web_page->title_);
+      page->description = std::move(web_page->description_);
+      if ((web_page->flags_ & WEBPAGE_FLAG_HAS_PHOTO) && web_page->photo_->get_id() == telegram_api::photo::ID) {
+        page->photo = get_photo(td_->file_manager_.get(), move_tl_object_as<telegram_api::photo>(web_page->photo_),
+                                owner_dialog_id);
+      } else {
+        page->photo.id = -2;
+      }
+      if (web_page->flags_ & WEBPAGE_FLAG_HAS_EMBEDDED_PREVIEW) {
+        page->embed_url = std::move(web_page->embed_url_);
+        page->embed_type = std::move(web_page->embed_type_);
+      }
+      if (web_page->flags_ & WEBPAGE_FLAG_HAS_EMBEDDED_PREVIEW_SIZE) {
+        page->embed_dimensions = get_dimensions(web_page->embed_width_, web_page->embed_height_);
+      }
+      if (web_page->flags_ & WEBPAGE_FLAG_HAS_DURATION) {
+        page->duration = web_page->duration_;
+        if (page->duration < 0) {
+          LOG(ERROR) << "Receive wrong web page duration " << page->duration;
+          page->duration = 0;
+        }
+      }
+      if (web_page->flags_ & WEBPAGE_FLAG_HAS_AUTHOR) {
+        page->author = std::move(web_page->author_);
+      }
+      if (web_page->flags_ & WEBPAGE_FLAG_HAS_DOCUMENT) {
+        int32 document_id = web_page->document_->get_id();
+        if (document_id == telegram_api::document::ID) {
+          auto parsed_document = td_->documents_manager_->on_get_document(
+              move_tl_object_as<telegram_api::document>(web_page->document_), owner_dialog_id);
+          page->document_type = parsed_document.first;
+          page->document_file_id = parsed_document.second;
+        }
+      }
+      if (web_page->flags_ & WEBPAGE_FLAG_HAS_INSTANT_VIEW) {
+        on_get_web_page_instant_view(page.get(), std::move(web_page->cached_page_), web_page->hash_, owner_dialog_id);
+      }
+
+      update_web_page(std::move(page), web_page_id, false, false);
+      return web_page_id;
+    }
+    case telegram_api::webPageNotModified::ID: {
+      LOG(ERROR) << "Receive webPageNotModified";
+      return WebPageId();
+    }
+    default:
+      UNREACHABLE();
+      return WebPageId();
+  }
+}
+
+void WebPagesManager::update_web_page(unique_ptr<WebPage> web_page, WebPageId web_page_id, bool from_binlog,
+                                      bool from_database) {
+  LOG(INFO) << "Update " << web_page_id;
+  CHECK(web_page != nullptr);
+
+  auto &page = web_pages_[web_page_id];
+  WebPageInstantView old_instant_view;
+  if (page != nullptr) {
+    old_instant_view = std::move(page->instant_view);
+    web_page->logevent_id = page->logevent_id;
+  }
+  page = std::move(web_page);
+
+  update_web_page_instant_view(web_page_id, page->instant_view, std::move(old_instant_view));
+
+  on_get_web_page_by_url(page->url, web_page_id, from_database);
+
+  update_messages_content(web_page_id, true);
+
+  if (!from_database) {
+    save_web_page(page.get(), web_page_id, from_binlog);
+  }
+}
+
+void WebPagesManager::update_web_page_instant_view(WebPageId web_page_id, WebPageInstantView &new_instant_view,
+                                                   WebPageInstantView &&old_instant_view) {
+  bool new_from_database = new_instant_view.was_loaded_from_database;
+  bool old_from_database = old_instant_view.was_loaded_from_database;
+  if (need_use_old_instant_view(new_instant_view, old_instant_view)) {
+    new_instant_view = std::move(old_instant_view);
+  }
+
+  if (G()->parameters().use_message_db && !new_instant_view.is_empty && new_instant_view.is_loaded) {
+    // we have instant view and probably want it to be saved
+    if (!new_from_database && !old_from_database) {
+      // if it wasn't loaded from the database, load it first
+      auto &load_web_page_instant_view_queries = load_web_page_instant_view_queries_[web_page_id];
+      auto previous_queries =
+          load_web_page_instant_view_queries.partial.size() + load_web_page_instant_view_queries.full.size();
+      if (previous_queries == 0) {
+        // try to load it only if there is no pending load queries
+        load_web_page_instant_view(web_page_id, false, Auto());
+        return;
+      }
+    }
+
+    if (!new_instant_view.was_loaded_from_database) {
+      LOG(INFO) << "Save instant view of " << web_page_id << " to database";
+      /*
+      if (web_page_id.get() == 0) {
+        auto blocks = std::move(new_instant_view.page_blocks);
+        new_instant_view.page_blocks.clear();
+        for (size_t i = 0; i < blocks.size(); i++) {
+          LOG(ERROR) << to_string(blocks[i]->get_page_block_object());
+          new_instant_view.page_blocks.push_back(std::move(blocks[i]));
+          log_event_store(new_instant_view);
+        }
+        UNREACHABLE();
+      }
+      */
+      new_instant_view.was_loaded_from_database = true;
+      G()->td_db()->get_sqlite_pmc()->set(get_web_page_instant_view_database_key(web_page_id),
+                                          log_event_store(new_instant_view).as_slice().str(), Auto());
+    }
+  }
+}
+
+bool WebPagesManager::need_use_old_instant_view(const WebPageInstantView &new_instant_view,
+                                                const WebPageInstantView &old_instant_view) {
+  LOG(INFO) << "Merge " << new_instant_view << " and " << old_instant_view;
+  if (old_instant_view.is_empty || !old_instant_view.is_loaded) {
+    return false;
+  }
+  if (new_instant_view.is_empty || !new_instant_view.is_loaded) {
+    return true;
+  }
+  if (new_instant_view.is_full != old_instant_view.is_full) {
+    return old_instant_view.is_full;
+  }
+
+  if (new_instant_view.hash == old_instant_view.hash) {
+    // the same instant view
+    return !new_instant_view.is_full || old_instant_view.is_full;
+  }
+
+  // data in database is always outdated
+  return new_instant_view.was_loaded_from_database;
+}
+
+void WebPagesManager::on_get_web_page_by_url(const string &url, WebPageId web_page_id, bool from_database) {
+  if (!from_database && G()->parameters().use_message_db) {
+    if (web_page_id.is_valid()) {
+      G()->td_db()->get_sqlite_pmc()->set(get_web_page_url_database_key(url), to_string(web_page_id.get()), Auto());
+    } else {
+      G()->td_db()->get_sqlite_pmc()->erase(get_web_page_url_database_key(url), Auto());
+    }
+  }
+
+  auto &cached_web_page_id = url_to_web_page_id_[url];
+  if (cached_web_page_id.is_valid() && web_page_id.is_valid() && web_page_id != cached_web_page_id) {
+    LOG(ERROR) << "Url \"" << url << "\" preview is changed from " << cached_web_page_id << " to " << web_page_id;
+  }
+
+  cached_web_page_id = web_page_id;
+}
+
+void WebPagesManager::wait_for_pending_web_page(DialogId dialog_id, MessageId message_id, WebPageId web_page_id) {
+  LOG(INFO) << "Waiting for " << web_page_id << " needed in " << message_id << " in " << dialog_id;
+  pending_web_pages_[web_page_id].emplace(dialog_id, message_id);
+  pending_web_pages_timeout_.add_timeout_in(web_page_id.get(), 1.0);
+}
+
+void WebPagesManager::on_get_web_page_preview_success(int64 request_id, const string &url,
+                                                      tl_object_ptr<telegram_api::MessageMedia> &&message_media_ptr,
+                                                      Promise<Unit> &&promise) {
+  CHECK(message_media_ptr != nullptr);
+  int32 constructor_id = message_media_ptr->get_id();
+  if (constructor_id != telegram_api::messageMediaWebPage::ID) {
+    if (constructor_id == telegram_api::messageMediaEmpty::ID) {
+      on_get_web_page_preview_success(request_id, url, WebPageId(), std::move(promise));
+      return;
+    }
+
+    LOG(ERROR) << "Receive " << to_string(message_media_ptr) << " instead of web page";
+    on_get_web_page_preview_fail(request_id, url, Status::Error(500, "Receive not web page in GetWebPagePreview"),
+                                 std::move(promise));
+    return;
+  }
+
+  auto message_media_web_page = move_tl_object_as<telegram_api::messageMediaWebPage>(message_media_ptr);
+  CHECK(message_media_web_page->webpage_ != nullptr);
+
+  auto web_page_id = on_get_web_page(std::move(message_media_web_page->webpage_), DialogId());
+  if (web_page_id.is_valid() && !have_web_page(web_page_id)) {
+    pending_get_web_pages_[web_page_id].emplace(request_id,
+                                                std::make_pair(url, std::move(promise)));  // TODO MultiPromise ?
+    pending_web_pages_timeout_.add_timeout_in(web_page_id.get(), 1.0);
+    return;
+  }
+
+  on_get_web_page_preview_success(request_id, url, web_page_id, std::move(promise));
+}
+
+void WebPagesManager::on_get_web_page_preview_success(int64 request_id, const string &url, WebPageId web_page_id,
+                                                      Promise<Unit> &&promise) {
+  CHECK(web_page_id == WebPageId() || have_web_page(web_page_id));
+
+  CHECK(got_web_page_previews_.find(request_id) == got_web_page_previews_.end());
+  got_web_page_previews_[request_id] = web_page_id;
+
+  if (web_page_id.is_valid() && !url.empty()) {
+    on_get_web_page_by_url(url, web_page_id, true);
+  }
+
+  promise.set_value(Unit());
+}
+
+void WebPagesManager::on_get_web_page_preview_fail(int64 request_id, const string &url, Status error,
+                                                   Promise<Unit> &&promise) {
+  LOG(INFO) << "Clean up getting of web page preview with url \"" << url << '"';
+  CHECK(error.is_error());
+  promise.set_error(std::move(error));
+}
+
+int64 WebPagesManager::get_web_page_preview(td_api::object_ptr<td_api::formattedText> &&text, Promise<Unit> &&promise) {
+  if (text == nullptr) {
+    promise.set_value(Unit());
+    return 0;
+  }
+
+  auto r_entities = get_message_entities(td_->contacts_manager_.get(), text->entities_);
+  if (r_entities.is_error()) {
+    promise.set_error(r_entities.move_as_error());
+    return 0;
+  }
+  auto entities = r_entities.move_as_ok();
+
+  auto result = fix_formatted_text(text->text_, entities, true, false, true, false);
+  if (text->text_.empty()) {
+    promise.set_value(Unit());
+    return 0;
+  }
+
+  auto url = get_first_url(text->text_, entities);
+  if (url.empty()) {
+    promise.set_value(Unit());
+    return 0;
+  }
+
+  LOG(INFO) << "Trying to get web page preview for message \"" << text->text_ << '"';
+  int64 request_id = get_web_page_preview_request_id_++;
+
+  auto web_page_id = get_web_page_by_url(url);
+  if (web_page_id.is_valid()) {
+    got_web_page_previews_[request_id] = web_page_id;
+    promise.set_value(Unit());
+  } else {
+    td_->create_handler<GetWebPagePreviewQuery>(std::move(promise))
+        ->send(text->text_, get_input_message_entities(td_->contacts_manager_.get(), entities), request_id,
+               std::move(url));
+  }
+  return request_id;
+}
+
+tl_object_ptr<td_api::webPage> WebPagesManager::get_web_page_preview_result(int64 request_id) {
+  if (request_id == 0) {
+    return nullptr;
+  }
+
+  auto it = got_web_page_previews_.find(request_id);
+  CHECK(it != got_web_page_previews_.end());
+  auto web_page_id = it->second;
+  got_web_page_previews_.erase(it);
+  return get_web_page_object(web_page_id);
+}
+
+WebPageId WebPagesManager::get_web_page_instant_view(const string &url, bool force_full, Promise<Unit> &&promise) {
+  LOG(INFO) << "Trying to get web page instant view for the url \"" << url << '"';
+  auto it = url_to_web_page_id_.find(url);
+  if (it != url_to_web_page_id_.end()) {
+    return get_web_page_instant_view(it->second, force_full, std::move(promise));
+  }
+
+  load_web_page_by_url(url, std::move(promise));
+  return WebPageId();
+}
+
+WebPageId WebPagesManager::get_web_page_instant_view(WebPageId web_page_id, bool force_full, Promise<Unit> &&promise) {
+  LOG(INFO) << "Trying to get web page instant view for " << web_page_id;
+
+  auto web_page_instant_view = get_web_page_instant_view(web_page_id);
+  if (web_page_instant_view == nullptr) {
+    promise.set_value(Unit());
+    return WebPageId();
+  }
+
+  if (!web_page_instant_view->is_loaded || (force_full && !web_page_instant_view->is_full)) {
+    load_web_page_instant_view(web_page_id, force_full, std::move(promise));
+    return WebPageId();
+  }
+
+  if (force_full) {
+    reload_web_page_instant_view(web_page_id);
+  }
+
+  promise.set_value(Unit());
+  return web_page_id;
+}
+
+string WebPagesManager::get_web_page_instant_view_database_key(WebPageId web_page_id) {
+  return "wpiv" + to_string(web_page_id.get());
+}
+
+void WebPagesManager::load_web_page_instant_view(WebPageId web_page_id, bool force_full, Promise<Unit> &&promise) {
+  auto &load_web_page_instant_view_queries = load_web_page_instant_view_queries_[web_page_id];
+  auto previous_queries =
+      load_web_page_instant_view_queries.partial.size() + load_web_page_instant_view_queries.full.size();
+  if (force_full) {
+    load_web_page_instant_view_queries.full.push_back(std::move(promise));
+  } else {
+    load_web_page_instant_view_queries.partial.push_back(std::move(promise));
+  }
+  LOG(INFO) << "Load " << web_page_id << " instant view, have " << previous_queries << " previous queries";
+  if (previous_queries == 0) {
+    const WebPageInstantView *web_page_instant_view = get_web_page_instant_view(web_page_id);
+    CHECK(web_page_instant_view != nullptr);
+
+    if (G()->parameters().use_message_db && !web_page_instant_view->was_loaded_from_database) {
+      LOG(INFO) << "Trying to load " << web_page_id << " instant view from database";
+      G()->td_db()->get_sqlite_pmc()->get(
+          get_web_page_instant_view_database_key(web_page_id), PromiseCreator::lambda([web_page_id](string value) {
+            send_closure(G()->web_pages_manager(), &WebPagesManager::on_load_web_page_instant_view_from_database,
+                         web_page_id, std::move(value));
+          }));
+    } else {
+      reload_web_page_instant_view(web_page_id);
+    }
+  }
+}
+
+void WebPagesManager::reload_web_page_instant_view(WebPageId web_page_id) {
+  LOG(INFO) << "Reload " << web_page_id << " instant view";
+  auto web_page = get_web_page(web_page_id);
+  CHECK(web_page != nullptr && !web_page->instant_view.is_empty);
+
+  auto promise = PromiseCreator::lambda([web_page_id](Result<> result) {
+    send_closure(G()->web_pages_manager(), &WebPagesManager::update_web_page_instant_view_load_requests, web_page_id,
+                 true, std::move(result));
+  });
+
+  td_->create_handler<GetWebPageQuery>(std::move(promise))
+      ->send(web_page->url, web_page->instant_view.is_full ? web_page->instant_view.hash : 0);
+}
+
+void WebPagesManager::on_load_web_page_instant_view_from_database(WebPageId web_page_id, string value) {
+  CHECK(G()->parameters().use_message_db);
+  LOG(INFO) << "Successfully loaded " << web_page_id << " instant view of size " << value.size() << " from database";
+  //  G()->td_db()->get_sqlite_pmc()->erase(get_web_page_instant_view_database_key(web_page_id), Auto());
+  //  return;
+
+  auto web_page_instant_view = get_web_page_instant_view(web_page_id);
+  if (web_page_instant_view == nullptr) {
+    // possible if web page loses preview/instant view
+    LOG(WARNING) << "There is no instant view in " << web_page_id;
+    if (!value.empty()) {
+      G()->td_db()->get_sqlite_pmc()->erase(get_web_page_instant_view_database_key(web_page_id), Auto());
+    }
+    update_web_page_instant_view_load_requests(web_page_id, true, Unit());
+    return;
+  }
+  if (web_page_instant_view->was_loaded_from_database) {
+    return;
+  }
+
+  WebPageInstantView result;
+  if (!value.empty()) {
+    if (log_event_parse(result, value).is_error()) {
+      result = WebPageInstantView();
+
+      LOG(INFO) << "Erase instant view in " << web_page_id << " from database";
+      G()->td_db()->get_sqlite_pmc()->erase(get_web_page_instant_view_database_key(web_page_id), Auto());
+    }
+  }
+  result.was_loaded_from_database = true;
+
+  update_web_page_instant_view(web_page_id, *web_page_instant_view, std::move(result));
+
+  update_web_page_instant_view_load_requests(web_page_id, false, Unit());
+}
+
+void WebPagesManager::update_web_page_instant_view_load_requests(WebPageId web_page_id, bool force_update,
+                                                                 Result<> result) {
+  // TODO [Error : 0 : Lost promise] on closing
+  LOG(INFO) << "Update load requests for " << web_page_id;
+  auto it = load_web_page_instant_view_queries_.find(web_page_id);
+  if (it == load_web_page_instant_view_queries_.end()) {
+    return;
+  }
+  vector<Promise<Unit>> promises[2];
+  promises[0] = std::move(it->second.partial);
+  promises[1] = std::move(it->second.full);
+  reset_to_empty(it->second.partial);
+  reset_to_empty(it->second.full);
+  load_web_page_instant_view_queries_.erase(it);
+
+  if (result.is_error()) {
+    LOG(INFO) << "Receive error " << result.error() << " for load " << web_page_id;
+    append(promises[0], std::move(promises[1]));
+    for (auto &promise : promises[0]) {
+      promise.set_error(result.error().clone());
+    }
+    return;
+  }
+  LOG(INFO) << "Successfully loaded web page " << web_page_id;
+
+  auto web_page_instant_view = get_web_page_instant_view(web_page_id);
+  if (web_page_instant_view == nullptr) {
+    append(promises[0], std::move(promises[1]));
+    for (auto &promise : promises[0]) {
+      promise.set_value(Unit());
+    }
+    return;
+  }
+  if (web_page_instant_view->is_loaded) {
+    if (web_page_instant_view->is_full) {
+      append(promises[0], std::move(promises[1]));
+      promises[1].clear();
+    }
+
+    for (auto &promise : promises[0]) {
+      promise.set_value(Unit());
+    }
+    promises[0].clear();
+  }
+  if (!promises[0].empty() || !promises[1].empty()) {
+    if (force_update) {
+      // protection from cycles
+      LOG(ERROR) << "Expected to receive " << web_page_id << " from the server, but didn't receive it";
+      append(promises[0], std::move(promises[1]));
+      for (auto &promise : promises[0]) {
+        promise.set_value(Unit());
+      }
+      return;
+    }
+    auto &load_queries = load_web_page_instant_view_queries_[web_page_id];
+    auto old_size = load_queries.partial.size() + load_queries.full.size();
+    append(load_queries.partial, std::move(promises[0]));
+    append(load_queries.full, std::move(promises[1]));
+    if (old_size == 0) {
+      reload_web_page_instant_view(web_page_id);
+    }
+  }
+}
+
+WebPageId WebPagesManager::get_web_page_by_url(const string &url) const {
+  if (url.empty()) {
+    return WebPageId();
+  }
+
+  LOG(INFO) << "Get web page id for the url \"" << url << '"';
+
+  auto it = url_to_web_page_id_.find(url);
+  if (it != url_to_web_page_id_.end()) {
+    return it->second;
+  }
+
+  return WebPageId();
+}
+
+WebPageId WebPagesManager::get_web_page_by_url(const string &url, Promise<Unit> &&promise) {
+  LOG(INFO) << "Trying to get web page id for the url \"" << url << '"';
+
+  auto it = url_to_web_page_id_.find(url);
+  if (it != url_to_web_page_id_.end()) {
+    promise.set_value(Unit());
+    return it->second;
+  }
+
+  load_web_page_by_url(url, std::move(promise));
+  return WebPageId();
+}
+
+void WebPagesManager::load_web_page_by_url(const string &url, Promise<Unit> &&promise) {
+  if (!G()->parameters().use_message_db) {
+    reload_web_page_by_url(url, std::move(promise));
+    return;
+  }
+
+  LOG(INFO) << "Load \"" << url << '"';
+  G()->td_db()->get_sqlite_pmc()->get(get_web_page_url_database_key(url),
+                                      PromiseCreator::lambda([url, promise = std::move(promise)](string value) mutable {
+                                        send_closure(G()->web_pages_manager(),
+                                                     &WebPagesManager::on_load_web_page_id_by_url_from_database, url,
+                                                     value, std::move(promise));
+                                      }));
+}
+
+void WebPagesManager::on_load_web_page_id_by_url_from_database(const string &url, string value,
+                                                               Promise<Unit> &&promise) {
+  LOG(INFO) << "Successfully loaded url \"" << url << "\" of size " << value.size() << " from database";
+  //  G()->td_db()->get_sqlite_pmc()->erase(get_web_page_url_database_key(web_page_id), Auto());
+  //  return;
+
+  auto it = url_to_web_page_id_.find(url);
+  if (it != url_to_web_page_id_.end()) {
+    // URL web page has already been loaded
+    promise.set_value(Unit());
+    return;
+  }
+  if (!value.empty()) {
+    auto web_page_id = WebPageId(to_integer<int64>(value));
+    if (web_page_id.is_valid()) {
+      if (have_web_page(web_page_id)) {
+        // URL web page has already been loaded
+        on_get_web_page_by_url(url, web_page_id, true);
+        promise.set_value(Unit());
+        return;
+      }
+
+      load_web_page_from_database(
+          web_page_id,
+          PromiseCreator::lambda([web_page_id, url, promise = std::move(promise)](Result<> result) mutable {
+            send_closure(G()->web_pages_manager(), &WebPagesManager::on_load_web_page_by_url_from_database, web_page_id,
+                         url, std::move(promise), std::move(result));
+          }));
+      return;
+    } else {
+      LOG(ERROR) << "Receive invalid " << web_page_id;
+    }
+  }
+
+  reload_web_page_by_url(url, std::move(promise));
+}
+
+void WebPagesManager::on_load_web_page_by_url_from_database(WebPageId web_page_id, const string &url,
+                                                            Promise<Unit> &&promise, Result<> result) {
+  if (result.is_error()) {
+    CHECK(G()->close_flag());
+    promise.set_error(Status::Error(500, "Request aborted"));
+    return;
+  }
+
+  auto web_page = get_web_page(web_page_id);
+  if (web_page == nullptr) {
+    reload_web_page_by_url(url, std::move(promise));
+    return;
+  }
+
+  if (web_page->url != url) {
+    on_get_web_page_by_url(url, web_page_id, true);
+  }
+
+  promise.set_value(Unit());
+}
+
+void WebPagesManager::reload_web_page_by_url(const string &url, Promise<Unit> &&promise) {
+  LOG(INFO) << "Reload url \"" << url << '"';
+  td_->create_handler<GetWebPageQuery>(std::move(promise))->send(url, 0);
+}
+
+SecretInputMedia WebPagesManager::get_secret_input_media(WebPageId web_page_id) const {
+  if (!web_page_id.is_valid()) {
+    return SecretInputMedia{};
+  }
+
+  auto web_page = get_web_page(web_page_id);
+  if (web_page == nullptr) {
+    return SecretInputMedia{};
+  }
+  return SecretInputMedia{nullptr, make_tl_object<secret_api::decryptedMessageMediaWebPage>(web_page->url)};
+}
+
+bool WebPagesManager::have_web_page(WebPageId web_page_id) const {
+  if (!web_page_id.is_valid()) {
+    return false;
+  }
+  return get_web_page(web_page_id) != nullptr;
+}
+
+tl_object_ptr<td_api::webPage> WebPagesManager::get_web_page_object(WebPageId web_page_id) const {
+  if (!web_page_id.is_valid()) {
+    return nullptr;
+  }
+  auto web_page = get_web_page(web_page_id);
+  if (web_page == nullptr) {
+    return nullptr;
+  }
+  return make_tl_object<td_api::webPage>(
+      web_page->url, web_page->display_url, web_page->type, web_page->site_name, web_page->title, web_page->description,
+      get_photo_object(td_->file_manager_.get(), &web_page->photo), web_page->embed_url, web_page->embed_type,
+      web_page->embed_dimensions.width, web_page->embed_dimensions.height, web_page->duration, web_page->author,
+      web_page->document_type == DocumentsManager::DocumentType::Animation
+          ? td_->animations_manager_->get_animation_object(web_page->document_file_id, "get_web_page_object")
+          : nullptr,
+      web_page->document_type == DocumentsManager::DocumentType::Audio
+          ? td_->audios_manager_->get_audio_object(web_page->document_file_id)
+          : nullptr,
+      web_page->document_type == DocumentsManager::DocumentType::General
+          ? td_->documents_manager_->get_document_object(web_page->document_file_id)
+          : nullptr,
+      web_page->document_type == DocumentsManager::DocumentType::Sticker
+          ? td_->stickers_manager_->get_sticker_object(web_page->document_file_id)
+          : nullptr,
+      web_page->document_type == DocumentsManager::DocumentType::Video
+          ? td_->videos_manager_->get_video_object(web_page->document_file_id)
+          : nullptr,
+      web_page->document_type == DocumentsManager::DocumentType::VideoNote
+          ? td_->video_notes_manager_->get_video_note_object(web_page->document_file_id)
+          : nullptr,
+      web_page->document_type == DocumentsManager::DocumentType::VoiceNote
+          ? td_->voice_notes_manager_->get_voice_note_object(web_page->document_file_id)
+          : nullptr,
+      !web_page->instant_view.is_empty);
+}
+
+tl_object_ptr<td_api::webPageInstantView> WebPagesManager::get_web_page_instant_view_object(
+    WebPageId web_page_id) const {
+  return get_web_page_instant_view_object(get_web_page_instant_view(web_page_id));
+}
+
+tl_object_ptr<td_api::webPageInstantView> WebPagesManager::get_web_page_instant_view_object(
+    const WebPageInstantView *web_page_instant_view) const {
+  if (web_page_instant_view == nullptr) {
+    return nullptr;
+  }
+  if (!web_page_instant_view->is_loaded) {
+    LOG(ERROR) << "Trying to get not loaded web page instant view";
+    return nullptr;
+  }
+  return make_tl_object<td_api::webPageInstantView>(
+      transform(web_page_instant_view->page_blocks,
+                [](const auto &page_block) { return page_block->get_page_block_object(); }),
+      web_page_instant_view->is_full);
+}
+
+void WebPagesManager::update_messages_content(WebPageId web_page_id, bool have_web_page) {
+  LOG(INFO) << "Update messages awaiting " << web_page_id;
+  auto it = pending_web_pages_.find(web_page_id);
+  if (it != pending_web_pages_.end()) {
+    auto full_message_ids = std::move(it->second);
+    pending_web_pages_.erase(it);
+    for (auto full_message_id : full_message_ids) {
+      send_closure_later(G()->messages_manager(), &MessagesManager::on_update_message_web_page, full_message_id,
+                         have_web_page);
+    }
+  }
+  auto get_it = pending_get_web_pages_.find(web_page_id);
+  if (get_it != pending_get_web_pages_.end()) {
+    auto requests = std::move(get_it->second);
+    pending_get_web_pages_.erase(get_it);
+    for (auto &request : requests) {
+      on_get_web_page_preview_success(request.first, request.second.first, have_web_page ? web_page_id : WebPageId(),
+                                      std::move(request.second.second));
+    }
+  }
+  pending_web_pages_timeout_.cancel_timeout(web_page_id.get());
+}
+
+WebPagesManager::WebPage *WebPagesManager::get_web_page(WebPageId web_page_id) {
+  auto p = web_pages_.find(web_page_id);
+  if (p == web_pages_.end()) {
+    return nullptr;
+  } else {
+    return p->second.get();
+  }
+}
+
+const WebPagesManager::WebPage *WebPagesManager::get_web_page(WebPageId web_page_id) const {
+  auto p = web_pages_.find(web_page_id);
+  if (p == web_pages_.end()) {
+    return nullptr;
+  } else {
+    return p->second.get();
+  }
+}
+
+WebPagesManager::WebPageInstantView *WebPagesManager::get_web_page_instant_view(WebPageId web_page_id) {
+  auto web_page = get_web_page(web_page_id);
+  if (web_page == nullptr || web_page->instant_view.is_empty) {
+    return nullptr;
+  }
+  return &web_page->instant_view;
+}
+
+const WebPagesManager::WebPageInstantView *WebPagesManager::get_web_page_instant_view(WebPageId web_page_id) const {
+  auto web_page = get_web_page(web_page_id);
+  if (web_page == nullptr || web_page->instant_view.is_empty) {
+    return nullptr;
+  }
+  return &web_page->instant_view;
+}
+
+void WebPagesManager::on_pending_web_page_timeout_callback(void *web_pages_manager_ptr, int64 web_page_id) {
+  static_cast<WebPagesManager *>(web_pages_manager_ptr)->on_pending_web_page_timeout(WebPageId(web_page_id));
+}
+
+void WebPagesManager::on_pending_web_page_timeout(WebPageId web_page_id) {
+  int32 count = 0;
+  auto it = pending_web_pages_.find(web_page_id);
+  if (it != pending_web_pages_.end()) {
+    vector<FullMessageId> full_message_ids;
+    for (auto full_message_id : it->second) {
+      full_message_ids.push_back(full_message_id);
+      count++;
+    }
+    send_closure_later(G()->messages_manager(), &MessagesManager::get_messages_from_server, std::move(full_message_ids),
+                       Promise<Unit>(), nullptr);
+  }
+  auto get_it = pending_get_web_pages_.find(web_page_id);
+  if (get_it != pending_get_web_pages_.end()) {
+    auto requests = std::move(get_it->second);
+    pending_get_web_pages_.erase(get_it);
+    for (auto &request : requests) {
+      on_get_web_page_preview_fail(request.first, request.second.first, Status::Error(500, "Request timeout exceeded"),
+                                   std::move(request.second.second));
+      count++;
+    }
+  }
+  if (count == 0) {
+    LOG(WARNING) << "Have no messages waiting for " << web_page_id;
+  }
+}
+
+WebPagesManager::RichText WebPagesManager::get_rich_text(tl_object_ptr<telegram_api::RichText> &&rich_text_ptr) {
+  CHECK(rich_text_ptr != nullptr);
+
+  RichText result;
+  switch (rich_text_ptr->get_id()) {
+    case telegram_api::textEmpty::ID:
+      break;
+    case telegram_api::textPlain::ID: {
+      auto rich_text = move_tl_object_as<telegram_api::textPlain>(rich_text_ptr);
+      result.content = std::move(rich_text->text_);
+      break;
+    }
+    case telegram_api::textBold::ID: {
+      auto rich_text = move_tl_object_as<telegram_api::textBold>(rich_text_ptr);
+      result.type = RichText::Type::Bold;
+      result.texts.push_back(get_rich_text(std::move(rich_text->text_)));
+      break;
+    }
+    case telegram_api::textItalic::ID: {
+      auto rich_text = move_tl_object_as<telegram_api::textItalic>(rich_text_ptr);
+      result.type = RichText::Type::Italic;
+      result.texts.push_back(get_rich_text(std::move(rich_text->text_)));
+      break;
+    }
+    case telegram_api::textUnderline::ID: {
+      auto rich_text = move_tl_object_as<telegram_api::textUnderline>(rich_text_ptr);
+      result.type = RichText::Type::Underline;
+      result.texts.push_back(get_rich_text(std::move(rich_text->text_)));
+      break;
+    }
+    case telegram_api::textStrike::ID: {
+      auto rich_text = move_tl_object_as<telegram_api::textStrike>(rich_text_ptr);
+      result.type = RichText::Type::Strikethrough;
+      result.texts.push_back(get_rich_text(std::move(rich_text->text_)));
+      break;
+    }
+    case telegram_api::textFixed::ID: {
+      auto rich_text = move_tl_object_as<telegram_api::textFixed>(rich_text_ptr);
+      result.type = RichText::Type::Fixed;
+      result.texts.push_back(get_rich_text(std::move(rich_text->text_)));
+      break;
+    }
+    case telegram_api::textUrl::ID: {
+      auto rich_text = move_tl_object_as<telegram_api::textUrl>(rich_text_ptr);
+      result.type = RichText::Type::Url;
+      result.content = std::move(rich_text->url_);
+      result.texts.push_back(get_rich_text(std::move(rich_text->text_)));
+      break;
+    }
+    case telegram_api::textEmail::ID: {
+      auto rich_text = move_tl_object_as<telegram_api::textEmail>(rich_text_ptr);
+      result.type = RichText::Type::EmailAddress;
+      result.content = std::move(rich_text->email_);
+      result.texts.push_back(get_rich_text(std::move(rich_text->text_)));
+      break;
+    }
+    case telegram_api::textConcat::ID: {
+      auto rich_text = move_tl_object_as<telegram_api::textConcat>(rich_text_ptr);
+      result.type = RichText::Type::Concatenation;
+      result.texts.reserve(rich_text->texts_.size());
+      for (auto &text : rich_text->texts_) {
+        result.texts.push_back(get_rich_text(std::move(text)));
+      }
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+  return result;
+}
+
+vector<WebPagesManager::RichText> WebPagesManager::get_rich_texts(
+    vector<tl_object_ptr<telegram_api::RichText>> &&rich_text_ptrs) {
+  vector<RichText> result;
+  result.reserve(rich_text_ptrs.size());
+  for (auto &rich_text : rich_text_ptrs) {
+    result.push_back(get_rich_text(std::move(rich_text)));
+  }
+  return result;
+}
+
+tl_object_ptr<td_api::RichText> WebPagesManager::get_rich_text_object(const RichText &rich_text) {
+  switch (rich_text.type) {
+    case RichText::Type::Plain:
+      return make_tl_object<td_api::richTextPlain>(rich_text.content);
+    case RichText::Type::Bold:
+      return make_tl_object<td_api::richTextBold>(get_rich_text_object(rich_text.texts[0]));
+    case RichText::Type::Italic:
+      return make_tl_object<td_api::richTextItalic>(get_rich_text_object(rich_text.texts[0]));
+    case RichText::Type::Underline:
+      return make_tl_object<td_api::richTextUnderline>(get_rich_text_object(rich_text.texts[0]));
+    case RichText::Type::Strikethrough:
+      return make_tl_object<td_api::richTextStrikethrough>(get_rich_text_object(rich_text.texts[0]));
+    case RichText::Type::Fixed:
+      return make_tl_object<td_api::richTextFixed>(get_rich_text_object(rich_text.texts[0]));
+    case RichText::Type::Url:
+      return make_tl_object<td_api::richTextUrl>(get_rich_text_object(rich_text.texts[0]), rich_text.content);
+    case RichText::Type::EmailAddress:
+      return make_tl_object<td_api::richTextEmailAddress>(get_rich_text_object(rich_text.texts[0]), rich_text.content);
+    case RichText::Type::Concatenation: {
+      vector<tl_object_ptr<td_api::RichText>> texts;
+      texts.reserve(rich_text.texts.size());
+      for (auto &text : rich_text.texts) {
+        texts.push_back(get_rich_text_object(text));
+      }
+      return make_tl_object<td_api::richTexts>(std::move(texts));
+    }
+  }
+  UNREACHABLE();
+  return nullptr;
+}
+
+vector<tl_object_ptr<td_api::RichText>> WebPagesManager::get_rich_text_objects(const vector<RichText> &rich_texts) {
+  vector<tl_object_ptr<td_api::RichText>> result;
+  result.reserve(rich_texts.size());
+  for (auto &rich_text : rich_texts) {
+    result.push_back(get_rich_text_object(rich_text));
+  }
+  return result;
+}
+
+vector<tl_object_ptr<td_api::PageBlock>> WebPagesManager::get_page_block_objects(
+    const vector<unique_ptr<PageBlock>> &page_blocks) {
+  vector<tl_object_ptr<td_api::PageBlock>> result;
+  result.reserve(page_blocks.size());
+  for (auto &page_block : page_blocks) {
+    result.push_back(page_block->get_page_block_object());
+  }
+  return result;
+}
+
+unique_ptr<WebPagesManager::PageBlock> WebPagesManager::get_page_block(
+    tl_object_ptr<telegram_api::PageBlock> page_block_ptr, const std::unordered_map<int64, FileId> &animations,
+    const std::unordered_map<int64, FileId> &audios, const std::unordered_map<int64, Photo> &photos,
+    const std::unordered_map<int64, FileId> &videos) const {
+  CHECK(page_block_ptr != nullptr);
+  switch (page_block_ptr->get_id()) {
+    case telegram_api::pageBlockUnsupported::ID:
+      return nullptr;
+    case telegram_api::pageBlockTitle::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockTitle>(page_block_ptr);
+      return make_unique<PageBlockTitle>(get_rich_text(std::move(page_block->text_)));
+    }
+    case telegram_api::pageBlockSubtitle::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockSubtitle>(page_block_ptr);
+      return make_unique<PageBlockSubtitle>(get_rich_text(std::move(page_block->text_)));
+    }
+    case telegram_api::pageBlockAuthorDate::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockAuthorDate>(page_block_ptr);
+      return make_unique<PageBlockAuthorDate>(get_rich_text(std::move(page_block->author_)),
+                                              page_block->published_date_);
+    }
+    case telegram_api::pageBlockHeader::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockHeader>(page_block_ptr);
+      return make_unique<PageBlockHeader>(get_rich_text(std::move(page_block->text_)));
+    }
+    case telegram_api::pageBlockSubheader::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockSubheader>(page_block_ptr);
+      return make_unique<PageBlockSubheader>(get_rich_text(std::move(page_block->text_)));
+    }
+    case telegram_api::pageBlockParagraph::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockParagraph>(page_block_ptr);
+      return make_unique<PageBlockParagraph>(get_rich_text(std::move(page_block->text_)));
+    }
+    case telegram_api::pageBlockPreformatted::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockPreformatted>(page_block_ptr);
+      return make_unique<PageBlockPreformatted>(get_rich_text(std::move(page_block->text_)),
+                                                std::move(page_block->language_));
+    }
+    case telegram_api::pageBlockFooter::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockFooter>(page_block_ptr);
+      return make_unique<PageBlockFooter>(get_rich_text(std::move(page_block->text_)));
+    }
+    case telegram_api::pageBlockDivider::ID:
+      return make_unique<PageBlockDivider>();
+    case telegram_api::pageBlockAnchor::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockAnchor>(page_block_ptr);
+      return make_unique<PageBlockAnchor>(std::move(page_block->name_));
+    }
+    case telegram_api::pageBlockList::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockList>(page_block_ptr);
+      return make_unique<PageBlockList>(get_rich_texts(std::move(page_block->items_)), page_block->ordered_);
+    }
+    case telegram_api::pageBlockBlockquote::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockBlockquote>(page_block_ptr);
+      return make_unique<PageBlockBlockQuote>(get_rich_text(std::move(page_block->text_)),
+                                              get_rich_text(std::move(page_block->caption_)));
+    }
+    case telegram_api::pageBlockPullquote::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockPullquote>(page_block_ptr);
+      return make_unique<PageBlockPullQuote>(get_rich_text(std::move(page_block->text_)),
+                                             get_rich_text(std::move(page_block->caption_)));
+    }
+    case telegram_api::pageBlockPhoto::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockPhoto>(page_block_ptr);
+      auto it = photos.find(page_block->photo_id_);
+      Photo photo;
+      if (it == photos.end()) {
+        photo.id = -2;
+      } else {
+        photo = it->second;
+      }
+      return make_unique<PageBlockPhoto>(std::move(photo), get_rich_text(std::move(page_block->caption_)));
+    }
+    case telegram_api::pageBlockVideo::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockVideo>(page_block_ptr);
+      bool need_autoplay = (page_block->flags_ & telegram_api::pageBlockVideo::AUTOPLAY_MASK) != 0;
+      bool is_looped = (page_block->flags_ & telegram_api::pageBlockVideo::LOOP_MASK) != 0;
+      auto animations_it = animations.find(page_block->video_id_);
+      if (animations_it != animations.end()) {
+        LOG_IF(ERROR, !is_looped) << "Receive non-looped animation";
+        return make_unique<PageBlockAnimation>(animations_it->second, get_rich_text(std::move(page_block->caption_)),
+                                               need_autoplay);
+      }
+
+      auto it = videos.find(page_block->video_id_);
+      FileId video_file_id;
+      if (it != videos.end()) {
+        video_file_id = it->second;
+      }
+      return make_unique<PageBlockVideo>(video_file_id, get_rich_text(std::move(page_block->caption_)), need_autoplay,
+                                         is_looped);
+    }
+    case telegram_api::pageBlockCover::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockCover>(page_block_ptr);
+      auto cover = get_page_block(std::move(page_block->cover_), animations, audios, photos, videos);
+      if (cover == nullptr) {
+        return nullptr;
+      }
+      return make_unique<PageBlockCover>(std::move(cover));
+    }
+    case telegram_api::pageBlockEmbed::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockEmbed>(page_block_ptr);
+      bool is_full_width = (page_block->flags_ & telegram_api::pageBlockEmbed::FULL_WIDTH_MASK) != 0;
+      bool allow_scrolling = (page_block->flags_ & telegram_api::pageBlockEmbed::ALLOW_SCROLLING_MASK) != 0;
+      auto it = (page_block->flags_ & telegram_api::pageBlockEmbed::POSTER_PHOTO_ID_MASK) != 0
+                    ? photos.find(page_block->poster_photo_id_)
+                    : photos.end();
+      Photo poster_photo;
+      if (it == photos.end()) {
+        poster_photo.id = -2;
+      } else {
+        poster_photo = it->second;
+      }
+      return make_unique<PageBlockEmbedded>(std::move(page_block->url_), std::move(page_block->html_),
+                                            std::move(poster_photo), get_dimensions(page_block->w_, page_block->h_),
+                                            get_rich_text(std::move(page_block->caption_)), is_full_width,
+                                            allow_scrolling);
+    }
+    case telegram_api::pageBlockEmbedPost::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockEmbedPost>(page_block_ptr);
+      auto it = photos.find(page_block->author_photo_id_);
+      Photo author_photo;
+      if (it == photos.end()) {
+        author_photo.id = -2;
+      } else {
+        author_photo = it->second;
+      }
+      return make_unique<PageBlockEmbeddedPost>(
+          std::move(page_block->url_), std::move(page_block->author_), std::move(author_photo), page_block->date_,
+          get_page_blocks(std::move(page_block->blocks_), animations, audios, photos, videos),
+          get_rich_text(std::move(page_block->caption_)));
+    }
+    case telegram_api::pageBlockCollage::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockCollage>(page_block_ptr);
+      return make_unique<PageBlockCollage>(
+          get_page_blocks(std::move(page_block->items_), animations, audios, photos, videos),
+          get_rich_text(std::move(page_block->caption_)));
+    }
+    case telegram_api::pageBlockSlideshow::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockSlideshow>(page_block_ptr);
+      return make_unique<PageBlockSlideshow>(
+          get_page_blocks(std::move(page_block->items_), animations, audios, photos, videos),
+          get_rich_text(std::move(page_block->caption_)));
+    }
+    case telegram_api::pageBlockChannel::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockChannel>(page_block_ptr);
+      CHECK(page_block->channel_ != nullptr);
+      if (page_block->channel_->get_id() == telegram_api::channel::ID) {
+        auto channel = static_cast<telegram_api::channel *>(page_block->channel_.get());
+        ChannelId channel_id(channel->id_);
+        if (!channel_id.is_valid()) {
+          LOG(ERROR) << "Receive invalid " << channel_id;
+          return nullptr;
+        }
+
+        if (td_->contacts_manager_->have_channel_force(channel_id)) {
+          td_->contacts_manager_->on_get_chat(std::move(page_block->channel_));
+          LOG(INFO) << "Receive known min " << channel_id;
+          return make_unique<PageBlockChatLink>(td_->contacts_manager_->get_channel_title(channel_id),
+                                                *td_->contacts_manager_->get_channel_dialog_photo(channel_id),
+                                                td_->contacts_manager_->get_channel_username(channel_id));
+        } else {
+          return make_unique<PageBlockChatLink>(std::move(channel->title_),
+                                                get_dialog_photo(td_->file_manager_.get(), std::move(channel->photo_)),
+                                                std::move(channel->username_));
+        }
+      } else {
+        LOG(ERROR) << "Receive wrong channel " << to_string(page_block->channel_);
+        return nullptr;
+      }
+    }
+    case telegram_api::pageBlockAudio::ID: {
+      auto page_block = move_tl_object_as<telegram_api::pageBlockAudio>(page_block_ptr);
+      auto it = audios.find(page_block->audio_id_);
+      FileId audio_file_id;
+      if (it != audios.end()) {
+        audio_file_id = it->second;
+      }
+      return make_unique<PageBlockAudio>(audio_file_id, get_rich_text(std::move(page_block->caption_)));
+    }
+    default:
+      UNREACHABLE();
+  }
+  return nullptr;
+}
+
+vector<unique_ptr<WebPagesManager::PageBlock>> WebPagesManager::get_page_blocks(
+    vector<tl_object_ptr<telegram_api::PageBlock>> page_block_ptrs, const std::unordered_map<int64, FileId> &animations,
+    const std::unordered_map<int64, FileId> &audios, const std::unordered_map<int64, Photo> &photos,
+    const std::unordered_map<int64, FileId> &videos) const {
+  vector<unique_ptr<PageBlock>> result;
+  result.reserve(page_block_ptrs.size());
+  for (auto &page_block_ptr : page_block_ptrs) {
+    auto page_block = get_page_block(std::move(page_block_ptr), animations, audios, photos, videos);
+    if (page_block != nullptr) {
+      result.push_back(std::move(page_block));
+    }
+  }
+  return result;
+}
+
+void WebPagesManager::on_get_web_page_instant_view(WebPage *web_page, tl_object_ptr<telegram_api::Page> &&page_ptr,
+                                                   int32 hash, DialogId owner_dialog_id) {
+  CHECK(page_ptr != nullptr);
+  vector<tl_object_ptr<telegram_api::PageBlock>> page_block_ptrs;
+  vector<tl_object_ptr<telegram_api::Photo>> photo_ptrs;
+  vector<tl_object_ptr<telegram_api::Document>> document_ptrs;
+  downcast_call(*page_ptr, [&](auto &page) {
+    page_block_ptrs = std::move(page.blocks_);
+    photo_ptrs = std::move(page.photos_);
+    document_ptrs = std::move(page.documents_);
+  });
+
+  std::unordered_map<int64, Photo> photos;
+  for (auto &photo_ptr : photo_ptrs) {
+    if (photo_ptr->get_id() == telegram_api::photo::ID) {
+      Photo photo =
+          get_photo(td_->file_manager_.get(), move_tl_object_as<telegram_api::photo>(photo_ptr), owner_dialog_id);
+      int64 photo_id = photo.id;
+      photos.emplace(photo_id, std::move(photo));
+    }
+  }
+  if (web_page->photo.id != -2 && web_page->photo.id != 0) {
+    photos.emplace(web_page->photo.id, web_page->photo);
+  }
+
+  std::unordered_map<int64, FileId> animations;
+  std::unordered_map<int64, FileId> audios;
+  std::unordered_map<int64, FileId> videos;
+  for (auto &document_ptr : document_ptrs) {
+    if (document_ptr->get_id() == telegram_api::document::ID) {
+      auto document = move_tl_object_as<telegram_api::document>(document_ptr);
+      auto document_id = document->id_;
+      auto parsed_document = td_->documents_manager_->on_get_document(std::move(document), owner_dialog_id);
+      if (parsed_document.first == DocumentsManager::DocumentType::Animation) {
+        animations.emplace(document_id, parsed_document.second);
+      } else if (parsed_document.first == DocumentsManager::DocumentType::Audio) {
+        audios.emplace(document_id, parsed_document.second);
+      } else if (parsed_document.first == DocumentsManager::DocumentType::Video) {
+        videos.emplace(document_id, parsed_document.second);
+      } else {
+        LOG(ERROR) << "Receive document of the wrong type " << static_cast<int32>(parsed_document.first);
+      }
+    }
+  }
+  if (web_page->document_type == DocumentsManager::DocumentType::Animation) {
+    auto file_view = td_->file_manager_->get_file_view(web_page->document_file_id);
+    if (file_view.has_remote_location()) {
+      animations.emplace(file_view.remote_location().get_id(), web_page->document_file_id);
+    } else {
+      LOG(ERROR) << "Animation has no remote location";
+    }
+  }
+  if (web_page->document_type == DocumentsManager::DocumentType::Audio) {
+    auto file_view = td_->file_manager_->get_file_view(web_page->document_file_id);
+    if (file_view.has_remote_location()) {
+      audios.emplace(file_view.remote_location().get_id(), web_page->document_file_id);
+    } else {
+      LOG(ERROR) << "Audio has no remote location";
+    }
+  }
+  if (web_page->document_type == DocumentsManager::DocumentType::Video) {
+    auto file_view = td_->file_manager_->get_file_view(web_page->document_file_id);
+    if (file_view.has_remote_location()) {
+      videos.emplace(file_view.remote_location().get_id(), web_page->document_file_id);
+    } else {
+      LOG(ERROR) << "Video has no remote location";
+    }
+  }
+
+  LOG(INFO) << "Receive a web page instant view with " << page_block_ptrs.size() << " blocks, " << animations.size()
+            << " animations, " << audios.size() << " audios, " << photos.size() << " photos and " << videos.size()
+            << " videos";
+  web_page->instant_view.page_blocks = get_page_blocks(std::move(page_block_ptrs), animations, audios, photos, videos);
+  web_page->instant_view.hash = hash;
+  web_page->instant_view.is_empty = false;
+  web_page->instant_view.is_full = page_ptr->get_id() == telegram_api::pageFull::ID;
+  web_page->instant_view.is_loaded = true;
+
+  LOG(DEBUG) << "Receive web page instant view: "
+             << to_string(get_web_page_instant_view_object(&web_page->instant_view));
+}
+
+class WebPagesManager::WebPageLogEvent {
+ public:
+  WebPageId web_page_id;
+  const WebPage *web_page_in;
+  unique_ptr<WebPage> web_page_out;
+
+  WebPageLogEvent() = default;
+
+  WebPageLogEvent(WebPageId web_page_id, const WebPage *web_page) : web_page_id(web_page_id), web_page_in(web_page) {
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(web_page_id, storer);
+    td::store(*web_page_in, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(web_page_id, parser);
+    CHECK(web_page_out == nullptr);
+    web_page_out = make_unique<WebPage>();
+    td::parse(*web_page_out, parser);
+  }
+};
+
+void WebPagesManager::save_web_page(WebPage *web_page, WebPageId web_page_id, bool from_binlog) {
+  if (!G()->parameters().use_message_db) {
+    return;
+  }
+
+  CHECK(web_page != nullptr);
+  if (!from_binlog) {
+    WebPageLogEvent logevent(web_page_id, web_page);
+    LogEventStorerImpl<WebPageLogEvent> storer(logevent);
+    if (web_page->logevent_id == 0) {
+      web_page->logevent_id = BinlogHelper::add(G()->td_db()->get_binlog(), LogEvent::HandlerType::WebPages, storer);
+    } else {
+      BinlogHelper::rewrite(G()->td_db()->get_binlog(), web_page->logevent_id, LogEvent::HandlerType::WebPages, storer);
+    }
+  }
+
+  LOG(INFO) << "Save " << web_page_id << " to database";
+  G()->td_db()->get_sqlite_pmc()->set(
+      get_web_page_database_key(web_page_id), log_event_store(*web_page).as_slice().str(),
+      PromiseCreator::lambda([web_page_id](Result<> result) {
+        send_closure(G()->web_pages_manager(), &WebPagesManager::on_save_web_page_to_database, web_page_id,
+                     result.is_ok());
+      }));
+}
+
+string WebPagesManager::get_web_page_url_database_key(const string &url) {
+  return "wpurl" + url;
+}
+
+void WebPagesManager::on_binlog_web_page_event(BinlogEvent &&event) {
+  if (!G()->parameters().use_message_db) {
+    BinlogHelper::erase(G()->td_db()->get_binlog(), event.id_);
+    return;
+  }
+
+  WebPageLogEvent log_event;
+  log_event_parse(log_event, event.data_).ensure();
+
+  auto web_page_id = log_event.web_page_id;
+  LOG(INFO) << "Add " << web_page_id << " from binlog";
+  auto web_page = std::move(log_event.web_page_out);
+  CHECK(web_page != nullptr);
+
+  web_page->logevent_id = event.id_;
+
+  update_web_page(std::move(web_page), web_page_id, true, false);
+}
+
+string WebPagesManager::get_web_page_database_key(WebPageId web_page_id) {
+  return "wp" + to_string(web_page_id.get());
+}
+
+void WebPagesManager::on_save_web_page_to_database(WebPageId web_page_id, bool success) {
+  WebPage *web_page = get_web_page(web_page_id);
+  if (web_page == nullptr) {
+    LOG(ERROR) << "Can't find " << (success ? "saved " : "failed to save ") << web_page_id;
+    return;
+  }
+
+  if (!success) {
+    LOG(ERROR) << "Failed to save " << web_page_id << " to database";
+    save_web_page(web_page, web_page_id, web_page->logevent_id != 0);
+  } else {
+    LOG(INFO) << "Successfully saved " << web_page_id << " to database";
+    if (web_page->logevent_id != 0) {
+      LOG(INFO) << "Erase " << web_page_id << " from binlog";
+      BinlogHelper::erase(G()->td_db()->get_binlog(), web_page->logevent_id);
+      web_page->logevent_id = 0;
+    }
+  }
+}
+
+void WebPagesManager::load_web_page_from_database(WebPageId web_page_id, Promise<Unit> promise) {
+  if (!G()->parameters().use_message_db || loaded_from_database_web_pages_.count(web_page_id)) {
+    promise.set_value(Unit());
+    return;
+  }
+
+  LOG(INFO) << "Load " << web_page_id << " from database";
+  auto &load_web_page_queries = load_web_page_from_database_queries_[web_page_id];
+  load_web_page_queries.push_back(std::move(promise));
+  if (load_web_page_queries.size() == 1u) {
+    G()->td_db()->get_sqlite_pmc()->get(
+        get_web_page_database_key(web_page_id), PromiseCreator::lambda([web_page_id](string value) {
+          send_closure(G()->web_pages_manager(), &WebPagesManager::on_load_web_page_from_database, web_page_id,
+                       std::move(value));
+        }));
+  }
+}
+
+void WebPagesManager::on_load_web_page_from_database(WebPageId web_page_id, string value) {
+  if (!loaded_from_database_web_pages_.insert(web_page_id).second) {
+    return;
+  }
+
+  auto it = load_web_page_from_database_queries_.find(web_page_id);
+  vector<Promise<Unit>> promises;
+  if (it != load_web_page_from_database_queries_.end()) {
+    promises = std::move(it->second);
+    CHECK(!promises.empty());
+    load_web_page_from_database_queries_.erase(it);
+  }
+
+  LOG(INFO) << "Successfully loaded " << web_page_id << " of size " << value.size() << " from database";
+  //  G()->td_db()->get_sqlite_pmc()->erase(get_web_page_database_key(web_page_id), Auto());
+  //  return;
+
+  WebPage *web_page = get_web_page(web_page_id);
+  if (web_page == nullptr) {
+    if (!value.empty()) {
+      auto result = make_unique<WebPage>();
+      log_event_parse(*result, value).ensure();
+      update_web_page(std::move(result), web_page_id, true, true);
+    }
+  } else {
+    // web page has already been loaded from the server
+  }
+
+  for (auto &promise : promises) {
+    promise.set_value(Unit());
+  }
+}
+
+bool WebPagesManager::have_web_page_force(WebPageId web_page_id) {
+  return get_web_page_force(web_page_id) != nullptr;
+}
+
+WebPagesManager::WebPage *WebPagesManager::get_web_page_force(WebPageId web_page_id) {
+  WebPage *web_page = get_web_page(web_page_id);
+  if (web_page != nullptr) {
+    return web_page;
+  }
+  if (!G()->parameters().use_message_db) {
+    return nullptr;
+  }
+  if (loaded_from_database_web_pages_.count(web_page_id)) {
+    return nullptr;
+  }
+
+  LOG(INFO) << "Try load " << web_page_id << " from database";
+  on_load_web_page_from_database(web_page_id,
+                                 G()->td_db()->get_sqlite_sync_pmc()->get(get_web_page_database_key(web_page_id)));
+  return get_web_page(web_page_id);
+}
+
+string WebPagesManager::get_web_page_search_text(WebPageId web_page_id) const {
+  auto *web_page = get_web_page(web_page_id);
+  if (web_page == nullptr) {
+    return "";
+  }
+  return PSTRING() << web_page->title + " " + web_page->description;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/WebPagesManager.h b/libs/tdlib/td/td/telegram/WebPagesManager.h
new file mode 100644
index 0000000000..7c491a8f78
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/WebPagesManager.h
@@ -0,0 +1,247 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/DialogId.h"
+#include "td/telegram/files/FileId.h"
+#include "td/telegram/MessageId.h"
+#include "td/telegram/Photo.h"
+#include "td/telegram/WebPageId.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+#include "td/actor/Timeout.h"
+
+#include "td/db/binlog/BinlogEvent.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Status.h"
+
+#include <unordered_map>
+#include <unordered_set>
+#include <utility>
+
+namespace td {
+
+class Td;
+
+class WebPagesManager : public Actor {
+ public:
+  WebPagesManager(Td *td, ActorShared<> parent);
+
+  WebPagesManager(const WebPagesManager &) = delete;
+  WebPagesManager &operator=(const WebPagesManager &) = delete;
+  WebPagesManager(WebPagesManager &&) = delete;
+  WebPagesManager &operator=(WebPagesManager &&) = delete;
+  ~WebPagesManager() override;
+
+  WebPageId on_get_web_page(tl_object_ptr<telegram_api::WebPage> &&web_page_ptr, DialogId owner_dialog_id);
+
+  void on_get_web_page_by_url(const string &url, WebPageId web_page_id, bool from_database);
+
+  void wait_for_pending_web_page(DialogId dialog_id, MessageId message_id, WebPageId web_page_id);
+
+  bool have_web_page(WebPageId web_page_id) const;
+
+  bool have_web_page_force(WebPageId web_page_id);
+
+  tl_object_ptr<td_api::webPage> get_web_page_object(WebPageId web_page_id) const;
+
+  tl_object_ptr<td_api::webPageInstantView> get_web_page_instant_view_object(WebPageId web_page_id) const;
+
+  int64 get_web_page_preview(td_api::object_ptr<td_api::formattedText> &&text, Promise<Unit> &&promise);
+
+  tl_object_ptr<td_api::webPage> get_web_page_preview_result(int64 request_id);
+
+  WebPageId get_web_page_instant_view(const string &url, bool force_full, Promise<Unit> &&promise);
+
+  WebPageId get_web_page_by_url(const string &url) const;
+
+  WebPageId get_web_page_by_url(const string &url, Promise<Unit> &&promise);
+
+  void on_get_web_page_preview_success(int64 request_id, const string &url,
+                                       tl_object_ptr<telegram_api::MessageMedia> &&message_media_ptr,
+                                       Promise<Unit> &&promise);
+
+  void on_get_web_page_preview_fail(int64 request_id, const string &url, Status error, Promise<Unit> &&promise);
+
+  SecretInputMedia get_secret_input_media(WebPageId web_page_id) const;
+
+  void on_binlog_web_page_event(BinlogEvent &&event);
+
+  string get_web_page_search_text(WebPageId web_page_id) const;
+
+ private:
+  static constexpr int32 WEBPAGE_FLAG_HAS_TYPE = 1;
+  static constexpr int32 WEBPAGE_FLAG_HAS_SITE_NAME = 2;
+  static constexpr int32 WEBPAGE_FLAG_HAS_TITLE = 4;
+  static constexpr int32 WEBPAGE_FLAG_HAS_DESCRIPTION = 8;
+  static constexpr int32 WEBPAGE_FLAG_HAS_PHOTO = 16;
+  static constexpr int32 WEBPAGE_FLAG_HAS_EMBEDDED_PREVIEW = 32;
+  static constexpr int32 WEBPAGE_FLAG_HAS_EMBEDDED_PREVIEW_SIZE = 64;
+  static constexpr int32 WEBPAGE_FLAG_HAS_DURATION = 128;
+  static constexpr int32 WEBPAGE_FLAG_HAS_AUTHOR = 256;
+  static constexpr int32 WEBPAGE_FLAG_HAS_DOCUMENT = 512;
+  static constexpr int32 WEBPAGE_FLAG_HAS_INSTANT_VIEW = 1024;
+
+  class WebPage;
+
+  class RichText;
+
+  class PageBlock;
+  class PageBlockTitle;
+  class PageBlockSubtitle;
+  class PageBlockAuthorDate;
+  class PageBlockHeader;
+  class PageBlockSubheader;
+  class PageBlockParagraph;
+  class PageBlockPreformatted;
+  class PageBlockFooter;
+  class PageBlockDivider;
+  class PageBlockAnchor;
+  class PageBlockList;
+  class PageBlockBlockQuote;
+  class PageBlockPullQuote;
+  class PageBlockAnimation;
+  class PageBlockPhoto;
+  class PageBlockVideo;
+  class PageBlockCover;
+  class PageBlockEmbedded;
+  class PageBlockEmbeddedPost;
+  class PageBlockCollage;
+  class PageBlockSlideshow;
+  class PageBlockChatLink;
+  class PageBlockAudio;
+
+  class WebPageInstantView;
+
+  class WebPageLogEvent;
+
+  template <class T>
+  friend void store(const unique_ptr<PageBlock> &block, T &storer);
+
+  template <class T>
+  friend void parse(unique_ptr<PageBlock> &block, T &parser);
+
+  void update_web_page(unique_ptr<WebPage> web_page, WebPageId web_page_id, bool from_binlog, bool from_database);
+
+  void update_web_page_instant_view(WebPageId web_page_id, WebPageInstantView &new_instant_view,
+                                    WebPageInstantView &&old_instant_view);
+
+  static bool need_use_old_instant_view(const WebPageInstantView &new_instant_view,
+                                        const WebPageInstantView &old_instant_view);
+
+  void update_messages_content(WebPageId web_page_id, bool have_web_page);
+
+  WebPage *get_web_page(WebPageId web_page_id);
+  const WebPage *get_web_page(WebPageId web_page_id) const;
+
+  WebPageInstantView *get_web_page_instant_view(WebPageId web_page_id);
+
+  const WebPageInstantView *get_web_page_instant_view(WebPageId web_page_id) const;
+
+  WebPageId get_web_page_instant_view(WebPageId web_page_id, bool force_full, Promise<Unit> &&promise);
+
+  tl_object_ptr<td_api::webPageInstantView> get_web_page_instant_view_object(
+      const WebPageInstantView *web_page_instant_view) const;
+
+  static void on_pending_web_page_timeout_callback(void *web_pages_manager_ptr, int64 web_page_id);
+  void on_pending_web_page_timeout(WebPageId web_page_id);
+
+  void on_get_web_page_preview_success(int64 request_id, const string &url, WebPageId web_page_id,
+                                       Promise<Unit> &&promise);
+
+  static RichText get_rich_text(tl_object_ptr<telegram_api::RichText> &&rich_text_ptr);
+
+  static vector<RichText> get_rich_texts(vector<tl_object_ptr<telegram_api::RichText>> &&rich_text_ptrs);
+
+  static tl_object_ptr<td_api::RichText> get_rich_text_object(const RichText &rich_text);
+
+  static vector<tl_object_ptr<td_api::RichText>> get_rich_text_objects(const vector<RichText> &rich_texts);
+
+  static vector<tl_object_ptr<td_api::PageBlock>> get_page_block_objects(
+      const vector<unique_ptr<PageBlock>> &page_blocks);
+
+  unique_ptr<PageBlock> get_page_block(tl_object_ptr<telegram_api::PageBlock> page_block_ptr,
+                                       const std::unordered_map<int64, FileId> &animations,
+                                       const std::unordered_map<int64, FileId> &audios,
+                                       const std::unordered_map<int64, Photo> &photos,
+                                       const std::unordered_map<int64, FileId> &videos) const;
+
+  vector<unique_ptr<PageBlock>> get_page_blocks(vector<tl_object_ptr<telegram_api::PageBlock>> page_block_ptrs,
+                                                const std::unordered_map<int64, FileId> &animations,
+                                                const std::unordered_map<int64, FileId> &audios,
+                                                const std::unordered_map<int64, Photo> &photos,
+                                                const std::unordered_map<int64, FileId> &videos) const;
+
+  void on_get_web_page_instant_view(WebPage *web_page, tl_object_ptr<telegram_api::Page> &&page_ptr, int32 hash,
+                                    DialogId owner_dialog_id);
+
+  void save_web_page(WebPage *web_page, WebPageId web_page_id, bool from_binlog);
+
+  static string get_web_page_database_key(WebPageId web_page_id);
+
+  void on_save_web_page_to_database(WebPageId web_page_id, bool success);
+
+  void load_web_page_from_database(WebPageId web_page_id, Promise<Unit> promise);
+
+  void on_load_web_page_from_database(WebPageId web_page_id, string value);
+
+  WebPage *get_web_page_force(WebPageId web_page_id);
+
+  static string get_web_page_instant_view_database_key(WebPageId web_page_id);
+
+  void load_web_page_instant_view(WebPageId web_page_id, bool force_full, Promise<Unit> &&promise);
+
+  void on_load_web_page_instant_view_from_database(WebPageId web_page_id, string value);
+
+  void reload_web_page_instant_view(WebPageId web_page_id);
+
+  void update_web_page_instant_view_load_requests(WebPageId web_page_id, bool force_update, Result<> result);
+
+  static string get_web_page_url_database_key(const string &url);
+
+  void load_web_page_by_url(const string &url, Promise<Unit> &&promise);
+
+  void reload_web_page_by_url(const string &url, Promise<Unit> &&promise);
+
+  void on_load_web_page_id_by_url_from_database(const string &url, string value, Promise<Unit> &&promise);
+
+  void on_load_web_page_by_url_from_database(WebPageId web_page_id, const string &url, Promise<Unit> &&promise,
+                                             Result<> result);
+
+  void tear_down() override;
+
+  Td *td_;
+  ActorShared<> parent_;
+  std::unordered_map<WebPageId, unique_ptr<WebPage>, WebPageIdHash> web_pages_;
+
+  std::unordered_map<WebPageId, vector<Promise<Unit>>, WebPageIdHash> load_web_page_from_database_queries_;
+  std::unordered_set<WebPageId, WebPageIdHash> loaded_from_database_web_pages_;
+
+  struct PendingWebPageInstantViewQueries {
+    vector<Promise<Unit>> partial;
+    vector<Promise<Unit>> full;
+  };
+  std::unordered_map<WebPageId, PendingWebPageInstantViewQueries, WebPageIdHash> load_web_page_instant_view_queries_;
+
+  std::unordered_map<WebPageId, std::unordered_set<FullMessageId, FullMessageIdHash>, WebPageIdHash> pending_web_pages_;
+  std::unordered_map<WebPageId, std::unordered_map<int64, std::pair<string, Promise<Unit>>>, WebPageIdHash>
+      pending_get_web_pages_;
+
+  int64 get_web_page_preview_request_id_ = 1;
+  std::unordered_map<int64, WebPageId> got_web_page_previews_;
+
+  std::unordered_map<string, WebPageId> url_to_web_page_id_;
+
+  MultiTimeout pending_web_pages_timeout_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/cli.cpp b/libs/tdlib/td/td/telegram/cli.cpp
new file mode 100644
index 0000000000..ec69f8265e
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/cli.cpp
@@ -0,0 +1,3072 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/ClientActor.h"
+#include "td/telegram/Log.h"
+
+#include "td/telegram/td_api_json.h"
+
+#include "td/actor/actor.h"
+
+#include "td/tl/tl_json.h"  // should be included after td_api_json?
+
+#include "memprof/memprof.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/BufferedFd.h"
+#include "td/utils/FileLog.h"
+#include "td/utils/format.h"
+#include "td/utils/JsonBuilder.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/port/signals.h"
+#include "td/utils/port/Stat.h"
+#include "td/utils/port/thread_local.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/Time.h"
+
+#ifndef USE_READLINE
+#include "td/utils/find_boundary.h"
+#endif
+
+#include <algorithm>
+#include <array>
+#include <atomic>
+#include <clocale>
+#include <cstdlib>
+#include <cstring>  // for strcmp
+#include <ctime>
+#include <iostream>
+#include <limits>
+#include <locale>
+#include <memory>
+#include <queue>
+#include <tuple>
+#include <unordered_map>
+
+#ifdef USE_READLINE
+/* Standard readline include files. */
+#include <readline/history.h>
+#include <readline/readline.h>
+#endif
+
+namespace td {
+
+static void dump_memory_usage() {
+  if (is_memprof_on()) {
+    LOG(WARNING) << "memory_dump";
+    clear_thread_locals();
+    std::vector<AllocInfo> v;
+    dump_alloc([&](const AllocInfo &info) { v.push_back(info); });
+    std::sort(v.begin(), v.end(), [](const AllocInfo &a, const AllocInfo &b) { return a.size > b.size; });
+    size_t total_size = 0;
+    size_t other_size = 0;
+    int cnt = 0;
+    for (auto &info : v) {
+      if (cnt++ < 50) {
+        LOG(WARNING) << td::format::as_size(info.size) << td::format::as_array(info.backtrace);
+      } else {
+        other_size += info.size;
+      }
+      total_size += info.size;
+    }
+    LOG(WARNING) << tag("other", td::format::as_size(other_size));
+    LOG(WARNING) << tag("total", td::format::as_size(total_size));
+    LOG(WARNING) << tag("total traces", get_ht_size());
+    LOG(WARNING) << tag("fast_backtrace_success_rate", get_fast_backtrace_success_rate());
+  }
+}
+
+#ifdef USE_READLINE
+const char *prompt = "td_cli> ";
+static int32 saved_point;
+static string saved_line;
+static std::atomic_flag readline_lock = ATOMIC_FLAG_INIT;
+
+static void deactivate_readline() {
+  while (readline_lock.test_and_set(std::memory_order_acquire)) {
+    // spin
+  }
+
+  saved_point = rl_point;
+  saved_line = string(rl_line_buffer, rl_end);
+
+  rl_set_prompt("");
+  rl_replace_line("", 0);
+  rl_redisplay();
+}
+
+static void reactivate_readline() {
+  rl_set_prompt(prompt);
+  rl_replace_line(saved_line.c_str(), 0);
+  rl_point = saved_point;
+  rl_redisplay();
+
+  readline_lock.clear(std::memory_order_release);
+}
+
+static char *command_generator(const char *text, int state) {
+  static vector<CSlice> commands{"GetContacts",
+                                 "GetChats",
+                                 "GetHistory",
+                                 "SetVerbosity",
+                                 "SendVideo",
+                                 "SearchDocument",
+                                 "GetChatMember",
+                                 "GetSupergroupAdministrators",
+                                 "GetSupergroupBanned",
+                                 "GetSupergroupMembers",
+                                 "GetFile",
+                                 "DownloadFile",
+                                 "CancelDownloadFile",
+                                 "ImportContacts",
+                                 "RemoveContacts",
+                                 "DumpNetQueries",
+                                 "CreateSecretChat",
+                                 "CreateNewSecretChat"};
+  static size_t cmd_i;
+  if (state == 0) {
+    cmd_i = 0;
+  }
+
+  while (cmd_i < commands.size()) {
+    const char *a = commands[cmd_i++].c_str();
+    const char *b = text;
+    const char *c = b;
+    while (*c && to_lower(*c) == *c) {
+      c++;
+    }
+    bool only_lowercase = !is_alpha(*c);
+    while (*a && *b) {
+      if (*a == *b || (only_lowercase && *a == to_upper(*b))) {
+        b++;
+      }
+      a++;
+    }
+    if (*b == 0) {
+// TODO call to strdup is completely wrong. Readline will try to call std::free() on the returned char*,
+// which may be incompatible with the std::malloc() called by strdup
+// It is especially likely to happen if Readline is used as dynamic library
+// Unfortunately Readline doesn't provide memory allocation functions/memory deallocation callbacks to fix this
+#if TD_MSVC
+      return _strdup(commands[cmd_i - 1].c_str());
+#else
+      return strdup(commands[cmd_i - 1].c_str());
+#endif
+    }
+  }
+  return nullptr;
+}
+
+static char **tg_cli_completion(const char *text, int start, int end) {
+  char **matches = nullptr;
+  if (start == 0) {
+    matches = rl_completion_matches(text, command_generator);
+  }
+  return matches;
+}
+#endif
+
+class CliLog : public LogInterface {
+ public:
+  void append(CSlice slice, int log_level) override {
+#ifdef USE_READLINE
+    deactivate_readline();
+#endif
+    if (log_level == VERBOSITY_NAME(PLAIN)) {
+#if TD_WINDOWS
+      TsCerr() << slice;
+#else
+      TsCerr() << TC_GREEN << slice << TC_EMPTY;
+#endif
+    } else {
+      default_log_interface->append(slice, log_level);
+    }
+#ifdef USE_READLINE
+    reactivate_readline();
+#endif
+  }
+  void rotate() override {
+  }
+};
+
+struct SendMessageInfo {
+  double start_time = 0;
+  double quick_ack_time = 0;
+  double ack_time = 0;
+  bool empty() const {
+    return quick_ack_time != 0 || ack_time != 0;
+  }
+};
+
+StringBuilder &operator<<(StringBuilder &sb, const SendMessageInfo &info) {
+  sb << format::cond(info.quick_ack_time != 0, tag("quick_ack", info.quick_ack_time - info.start_time));
+  sb << format::cond(info.ack_time != 0, tag("ack", info.ack_time - info.start_time));
+  return sb;
+}
+
+class CliClient final : public Actor {
+ public:
+  CliClient(bool use_test_dc, bool get_chat_list, bool disable_network, int32 api_id, string api_hash)
+      : use_test_dc_(use_test_dc)
+      , get_chat_list_(get_chat_list)
+      , disable_network_(disable_network)
+      , api_id_(api_id)
+      , api_hash_(api_hash) {
+  }
+
+  static void quit_instance() {
+    instance_->quit();
+  }
+
+ private:
+  void start_up() override {
+    yield();
+  }
+
+  std::unordered_map<uint64, SendMessageInfo> query_id_to_send_message_info_;
+  std::unordered_map<uint64, SendMessageInfo> message_id_to_send_message_info_;
+
+  struct User {
+    string first_name;
+    string last_name;
+    string username;
+  };
+
+  std::unordered_map<int32, User> users_;
+  std::unordered_map<string, int32> username_to_user_id_;
+
+  void register_user(const td_api::user &user) {
+    User &new_user = users_[user.id_];
+    new_user.first_name = user.first_name_;
+    new_user.last_name = user.last_name_;
+    new_user.username = user.username_;
+    username_to_user_id_[to_lower(new_user.username)] = user.id_;
+  }
+
+  void print_user(Logger &log, int32 user_id, bool full = false) {
+    const User *user = &users_[user_id];
+    log << user->first_name << " " << user->last_name << " #" << user_id;
+    if (!user->username.empty()) {
+      log << " @" << user->username;
+    }
+  }
+
+  void update_users(const td_api::users &users) {
+    Logger log{*log_interface, VERBOSITY_NAME(PLAIN)};
+    for (auto &user_id : users.user_ids_) {
+      if (user_id == 0) {
+        continue;
+      }
+      print_user(log, user_id);
+      log << "\n";
+    }
+  }
+
+  std::unordered_map<string, int32> username_to_supergroup_id;
+  void register_supergroup(const td_api::supergroup &supergroup) {
+    if (!supergroup.username_.empty()) {
+      username_to_supergroup_id[to_lower(supergroup.username_)] = supergroup.id_;
+    }
+  }
+
+  void update_option(const td_api::updateOption &option) {
+    if (option.name_ == "my_id") {
+      if (option.value_->get_id() == td_api::optionValueInteger::ID) {
+        my_id_ = static_cast<const td_api::optionValueInteger *>(option.value_.get())->value_;
+        LOG(INFO) << "Set my id to " << my_id_;
+      }
+    }
+  }
+
+  int64 get_history_chat_id = 0;
+  int64 search_chat_id = 0;
+  void on_get_messages(const td_api::messages &messages) {
+    if (get_history_chat_id != 0) {
+      int64 last_message_id = 0;
+      for (auto &m : messages.messages_) {
+        // LOG(PLAIN) << to_string(m);
+        if (m->content_->get_id() == td_api::messageText::ID) {
+          LOG(PLAIN) << td::oneline(static_cast<const td_api::messageText *>(m->content_.get())->text_->text_) << "\n";
+        }
+        last_message_id = m->id_;
+      }
+
+      if (last_message_id > 0) {
+        send_request(make_tl_object<td_api::getChatHistory>(get_history_chat_id, last_message_id, 0, 100, false));
+      } else {
+        get_history_chat_id = 0;
+      }
+    }
+    if (search_chat_id != 0) {
+      if (!messages.messages_.empty()) {
+        auto last_message_id = messages.messages_.back()->id_;
+        LOG(ERROR) << (last_message_id >> 20);
+        send_request(
+            make_tl_object<td_api::searchChatMessages>(search_chat_id, "", 0, last_message_id, 0, 100,
+                                                       make_tl_object<td_api::searchMessagesFilterPhotoAndVideo>()));
+      } else {
+        search_chat_id = 0;
+      }
+    }
+  }
+
+  void on_get_message(const td_api::message &message) {
+    if (message.sending_state_ != nullptr &&
+        message.sending_state_->get_id() == td_api::messageSendingStatePending::ID) {
+      // send_request(make_tl_object<td_api::deleteMessages>(message.chat_id_, vector<int64>{message.id_}, true));
+    }
+  }
+
+  struct FileGeneration {
+    int64 id = 0;
+    string destination;
+    string source;
+    int32 part_size = 0;
+    int32 local_size = 0;
+    int32 size = 0;
+  };
+
+  vector<FileGeneration> pending_file_generations;
+
+  void on_file_generation_start(const td_api::updateFileGenerationStart &update) {
+    FileGeneration file_generation;
+    file_generation.id = update.generation_id_;
+    file_generation.destination = update.destination_path_;
+    if (update.conversion_ == "#url#") {
+      // TODO: actually download
+      file_generation.source = "test.jpg";
+      file_generation.part_size = 1000000;
+    } else if (update.conversion_ == "skip") {
+      return;
+    } else {
+      file_generation.source = update.original_path_;
+      file_generation.part_size = to_integer<int32>(update.conversion_);
+    }
+
+    auto r_stat = stat(file_generation.source);
+    if (r_stat.is_ok()) {
+      auto size = r_stat.ok().size_;
+      if (size <= 0 || size > 1500000000) {
+        r_stat = Status::Error(400, size == 0 ? Slice("File is empty") : Slice("File is too big"));
+      }
+    }
+    if (r_stat.is_ok()) {
+      file_generation.size = narrow_cast<int32>(r_stat.ok().size_);
+      if (file_generation.part_size <= 0) {
+        file_generation.part_size = file_generation.size;
+      }
+      pending_file_generations.push_back(std::move(file_generation));
+      timeout_expired();
+    } else {
+      send_request(make_tl_object<td_api::finishFileGeneration>(
+          update.generation_id_, td_api::make_object<td_api::error>(400, r_stat.error().message().str())));
+    }
+  }
+
+  int64 as_chat_id(Slice str) const {
+    str = trim(str);
+    if (str[0] == '@') {
+      auto it = username_to_user_id_.find(to_lower(str.substr(1)));
+      if (it != username_to_user_id_.end()) {
+        return it->second;
+      }
+      auto it2 = username_to_supergroup_id.find(to_lower(str.substr(1)));
+      if (it2 != username_to_supergroup_id.end()) {
+        auto supergroup_id = it2->second;
+        return static_cast<int64>(-1000'000'000'000ll) - supergroup_id;
+      }
+      LOG(ERROR) << "Can't resolve " << str;
+      return 0;
+    }
+    if (str == "me") {
+      return my_id_;
+    }
+    return to_integer<int64>(str);
+  }
+
+  vector<int64> as_chat_ids(Slice chat_ids, char delimiter = ' ') const {
+    return transform(full_split(chat_ids, delimiter), [this](Slice str) { return as_chat_id(str); });
+  }
+
+  static int64 as_message_id(Slice str) {
+    str = trim(str);
+    if (!str.empty() && str.back() == 's') {
+      return to_integer<int32>(str) << 20;
+    }
+    return to_integer<int64>(str);
+  }
+
+  static vector<int64> as_message_ids(Slice message_ids, char delimiter = ' ') {
+    return transform(full_split(message_ids, delimiter), as_message_id);
+  }
+
+  int32 as_user_id(Slice str) const {
+    str = trim(str);
+    if (str[0] == '@') {
+      auto it = username_to_user_id_.find(to_lower(str.substr(1)));
+      if (it != username_to_user_id_.end()) {
+        return it->second;
+      }
+      LOG(ERROR) << "Can't find user " << str;
+      return 0;
+    }
+    if (str == "me") {
+      return my_id_;
+    }
+    return to_integer<int32>(str);
+  }
+
+  vector<int32> as_user_ids(Slice user_ids, char delimiter = ' ') const {
+    return transform(full_split(user_ids, delimiter), [this](Slice str) { return as_user_id(str); });
+  }
+
+  static int32 as_file_id(string str) {
+    return to_integer<int32>(trim(std::move(str)));
+  }
+
+  static int32 as_call_id(string str) {
+    return to_integer<int32>(trim(std::move(str)));
+  }
+
+  static td_api::object_ptr<td_api::InputFile> as_input_file_id(string str) {
+    return make_tl_object<td_api::inputFileId>(as_file_id(str));
+  }
+
+  static tl_object_ptr<td_api::InputFile> as_local_file(string path) {
+    return make_tl_object<td_api::inputFileLocal>(trim(std::move(path)));
+  }
+
+  static tl_object_ptr<td_api::InputFile> as_generated_file(string original_path, string conversion,
+                                                            int32 expected_size = 0) {
+    return make_tl_object<td_api::inputFileGenerated>(trim(original_path), trim(conversion), expected_size);
+  }
+
+  static tl_object_ptr<td_api::location> as_location(string latitude, string longitude) {
+    return make_tl_object<td_api::location>(to_double(latitude), to_double(longitude));
+  }
+
+  static bool as_bool(string str) {
+    str = to_lower(str);
+    return str == "true" || str == "1";
+  }
+
+  template <class T>
+  static vector<T> to_integers(Slice ids_string, char delimiter = ' ') {
+    return transform(full_split(ids_string, delimiter), to_integer<T>);
+  }
+
+  void on_result(uint64 id, tl_object_ptr<td_api::Object> result) {
+    if (id > 0 && GET_VERBOSITY_LEVEL() < VERBOSITY_NAME(td_requests)) {
+      LOG(ERROR) << "on_result [id=" << id << "] " << to_string(result);
+    }
+
+    auto as_json_str = json_encode<std::string>(ToJson(result));
+    // LOG(INFO) << "on_result [id=" << id << "] " << as_json_str;
+    auto copy_as_json_str = as_json_str;
+    auto as_json_value = json_decode(copy_as_json_str).move_as_ok();
+    td_api::object_ptr<td_api::Object> object;
+    from_json(object, as_json_value).ensure();
+    CHECK(object != nullptr);
+    auto as_json_str2 = json_encode<std::string>(ToJson(object));
+    CHECK(as_json_str == as_json_str2) << "\n" << tag("a", as_json_str) << "\n" << tag("b", as_json_str2);
+    // LOG(INFO) << "on_result [id=" << id << "] " << as_json_str;
+
+    int32 result_id = result == nullptr ? 0 : result->get_id();
+
+    [&] {
+      if (id != 0) {
+        auto it = query_id_to_send_message_info_.find(id);
+        if (it == query_id_to_send_message_info_.end()) {
+          return;
+        }
+        auto info = it->second;
+        query_id_to_send_message_info_.erase(id);
+
+        if (result_id == td_api::message::ID) {
+          auto *message = static_cast<const td_api::message *>(result.get());
+          message_id_to_send_message_info_[message->id_] = info;
+        }
+      }
+    }();
+    [&] {
+      if (result_id == td_api::updateMessageSendAcknowledged::ID) {
+        auto *message = static_cast<const td_api::updateMessageSendAcknowledged *>(result.get());
+        auto it = message_id_to_send_message_info_.find(message->message_id_);
+        if (it == message_id_to_send_message_info_.end()) {
+          return;
+        }
+        auto &info = it->second;
+        info.quick_ack_time = Time::now();
+      }
+    }();
+    [&] {
+      if (result_id == td_api::updateMessageSendSucceeded::ID) {
+        auto *message = static_cast<const td_api::updateMessageSendSucceeded *>(result.get());
+        auto it = message_id_to_send_message_info_.find(message->old_message_id_);
+        if (it == message_id_to_send_message_info_.end()) {
+          return;
+        }
+        auto info = it->second;
+        message_id_to_send_message_info_.erase(it);
+        info.ack_time = Time::now();
+        LOG(INFO) << info;
+      }
+    }();
+
+    switch (result_id) {
+      case td_api::updateUser::ID:
+        register_user(*static_cast<const td_api::updateUser *>(result.get())->user_);
+        break;
+      case td_api::updateSupergroup::ID:
+        register_supergroup(*static_cast<const td_api::updateSupergroup *>(result.get())->supergroup_);
+        break;
+      case td_api::users::ID:
+        update_users(*static_cast<const td_api::users *>(result.get()));
+        break;
+      case td_api::updateOption::ID:
+        update_option(*static_cast<const td_api::updateOption *>(result.get()));
+        break;
+      case td_api::message::ID:
+        on_get_message(*static_cast<const td_api::message *>(result.get()));
+        break;
+      case td_api::messages::ID:
+        on_get_messages(*static_cast<const td_api::messages *>(result.get()));
+        break;
+      case td_api::updateFileGenerationStart::ID:
+        on_file_generation_start(*static_cast<const td_api::updateFileGenerationStart *>(result.get()));
+        break;
+      case td_api::updateChatLastMessage::ID: {
+        auto message = static_cast<const td_api::updateChatLastMessage *>(result.get())->last_message_.get();
+        if (message != nullptr && message->content_->get_id() == td_api::messageText::ID) {
+          // auto text = static_cast<const td_api::messageText *>(message->content_.get())->text_->text_;
+        }
+        break;
+      }
+    }
+  }
+
+  void on_error(uint64 id, tl_object_ptr<td_api::error> error) {
+    auto current_verbosity_level = GET_VERBOSITY_LEVEL();
+    SET_VERBOSITY_LEVEL(VERBOSITY_NAME(INFO));
+    LOG(INFO) << "on_error [id=" << id << "] " << to_string(error);
+    SET_VERBOSITY_LEVEL(current_verbosity_level);
+  }
+
+  void on_closed() {
+    LOG(INFO) << "on_closed";
+    ready_to_stop_ = true;
+    if (close_flag_) {
+      yield();
+      return;
+    }
+  }
+
+  void quit() {
+    if (close_flag_) {
+      return;
+    }
+
+    LOG(WARNING) << "QUIT";
+    close_flag_ = true;
+    dump_memory_usage();
+    td_.reset();
+#if TD_WINDOWS
+    stdin_reader_.reset();
+#else
+    is_stdin_reader_stopped_ = true;
+#endif
+    yield();
+  }
+
+#ifdef USE_READLINE
+  Fd stdin_;
+#else
+  using StreamConnection = BufferedFd<Fd>;
+  StreamConnection stdin_;
+#endif
+  static CliClient *instance_;
+
+#ifdef USE_READLINE
+  /* Callback function called for each line when accept-line executed, EOF
+   *    seen, or EOF character read.  This sets a flag and returns; it could
+   *       also call exit. */
+  static void cb_linehandler(char *line) {
+    /* Can use ^D (stty eof) to exit. */
+    if (line == nullptr) {
+      LOG(FATAL) << "closed";
+      return;
+    }
+    if (*line) {
+      add_history(line);
+    }
+    instance_->add_cmd(line);
+    rl_free(line);
+  }
+#endif
+
+  unique_ptr<TdCallback> make_td_callback() {
+    class TdCallbackImpl : public TdCallback {
+     public:
+      explicit TdCallbackImpl(CliClient *client) : client_(client) {
+      }
+      void on_result(uint64 id, tl_object_ptr<td_api::Object> result) override {
+        client_->on_result(id, std::move(result));
+      }
+      void on_error(uint64 id, tl_object_ptr<td_api::error> error) override {
+        client_->on_error(id, std::move(error));
+      }
+      void on_closed() override {
+        client_->on_closed();
+      }
+
+     private:
+      CliClient *client_;
+    };
+    return make_unique<TdCallbackImpl>(this);
+  }
+
+  void init_td() {
+    close_flag_ = false;
+    ready_to_stop_ = false;
+
+    td_ = create_actor<ClientActor>("ClientActor1", make_td_callback());
+    td_ = create_actor<ClientActor>("ClientActor2", make_td_callback());
+    ready_to_stop_ = false;
+
+    auto bad_parameters = td_api::make_object<td_api::tdlibParameters>();
+    bad_parameters->database_directory_ = "/..";
+    bad_parameters->api_id_ = api_id_;
+    bad_parameters->api_hash_ = api_hash_;
+    send_request(td_api::make_object<td_api::setTdlibParameters>(std::move(bad_parameters)));
+
+    auto parameters = td_api::make_object<td_api::tdlibParameters>();
+    parameters->use_test_dc_ = use_test_dc_;
+    parameters->use_message_database_ = true;
+    parameters->use_secret_chats_ = true;
+    parameters->api_id_ = api_id_;
+    parameters->api_hash_ = api_hash_;
+    parameters->system_language_code_ = "en";
+    parameters->device_model_ = "Desktop";
+    parameters->system_version_ = "Unknown";
+    parameters->application_version_ = "tg_cli";
+    send_request(td_api::make_object<td_api::setTdlibParameters>(std::move(parameters)));
+    send_request(td_api::make_object<td_api::checkDatabaseEncryptionKey>());
+
+    for (int i = 0; i < 4; i++) {
+      send_closure_later(td_, &ClientActor::request, std::numeric_limits<uint64>::max(),
+                         td_api::make_object<td_api::setAlarm>(0.001 + 1000 * (i / 2)));
+    }
+  }
+
+  void init() {
+    instance_ = this;
+
+    init_td();
+
+#if TD_WINDOWS
+    auto stdin_id = Scheduler::instance()->sched_count() - 1;
+    class StdinReader : public Actor {
+     public:
+      explicit StdinReader(ActorShared<CliClient> parent) : parent_(std::move(parent)) {
+      }
+      void start_up() override {
+        stdin_ = &Fd::Stdin();
+        set_timeout_in(0.001);
+      }
+      void timeout_expired() override {
+        std::array<char, 100> buf;
+        auto t_res = stdin_->read(MutableSlice(buf.data(), buf.size()));
+        if (t_res.is_error()) {
+          LOG(FATAL) << "Can't read from stdin";
+        }
+        auto res = t_res.ok();
+        VLOG(fd) << res << " " << string(buf.data(), res);
+        data_.append(string(buf.data(), res));
+        process();
+        set_timeout_in(0.05);
+      }
+
+     private:
+      Fd *stdin_ = nullptr;
+      string data_;
+      ActorShared<CliClient> parent_;
+      void process() {
+        while (true) {
+          auto pos = data_.find('\n');
+          if (pos == string::npos) {
+            break;
+          }
+          auto cmd = string(data_.data(), pos);
+          while (!cmd.empty() && cmd.back() == '\r') {
+            cmd.pop_back();
+          }
+          send_closure(parent_, &CliClient::on_cmd, cmd);
+          data_ = data_.substr(pos + 1);
+        }
+      }
+    };
+    stdin_reader_ = create_actor_on_scheduler<StdinReader>("stdin_reader", stdin_id, actor_shared(this, 1));
+#else
+    Fd::Stdin().set_is_blocking(false).ensure();
+#ifdef USE_READLINE
+    deactivate_readline();
+    rl_callback_handler_install(prompt, cb_linehandler);
+    rl_attempted_completion_function = tg_cli_completion;
+    reactivate_readline();
+
+    stdin_ = Fd::Stdin().clone();
+#else
+    stdin_ = StreamConnection(Fd::Stdin().clone());
+#endif
+    stdin_.get_fd().set_observer(this);
+    subscribe(stdin_, Fd::Read);
+#endif
+
+    if (get_chat_list_) {
+      send_request(make_tl_object<td_api::getChats>(std::numeric_limits<int64>::max(), 0, 100));
+    }
+    if (disable_network_) {
+      send_request(make_tl_object<td_api::setNetworkType>(make_tl_object<td_api::networkTypeNone>()));
+    }
+  }
+#ifndef USE_READLINE
+  size_t buffer_pos_ = 0;
+  Result<BufferSlice> process_stdin(ChainBufferReader *buffer) {
+    auto found = find_boundary(buffer->clone(), "\n", buffer_pos_);
+
+    if (!found) {
+      return Status::Error("End of line not found");
+    }
+
+    auto data = buffer->cut_head(buffer_pos_).move_as_buffer_slice();
+    if (!data.empty() && data[data.size() - 1] == '\r') {
+      data.truncate(data.size() - 1);
+    }
+    buffer->cut_head(1);
+    buffer_pos_ = 0;
+    return std::move(data);
+  }
+#endif
+
+  static tl_object_ptr<td_api::formattedText> as_caption(string caption,
+                                                         vector<td_api::object_ptr<td_api::textEntity>> entities = {}) {
+    if (entities.empty()) {
+      auto parsed_caption =
+          execute(make_tl_object<td_api::parseTextEntities>(caption, make_tl_object<td_api::textParseModeMarkdown>()));
+      if (parsed_caption->get_id() == td_api::formattedText::ID) {
+        return td_api::move_object_as<td_api::formattedText>(parsed_caption);
+      }
+    }
+    return make_tl_object<td_api::formattedText>(caption, std::move(entities));
+  }
+
+  tl_object_ptr<td_api::NotificationSettingsScope> get_notification_settings_scope(Slice scope) const {
+    if (scope == "users" || scope == "privateChats") {
+      return make_tl_object<td_api::notificationSettingsScopePrivateChats>();
+    } else if (scope == "chats" || scope == "groups" || scope == "groupChats") {
+      return make_tl_object<td_api::notificationSettingsScopeBasicGroupChats>();
+    } else if (scope == "all" || scope == "dialogs") {
+      return make_tl_object<td_api::notificationSettingsScopeAllChats>();
+    } else {
+      return make_tl_object<td_api::notificationSettingsScopeChat>(as_chat_id(scope));
+    }
+  }
+
+  static tl_object_ptr<td_api::UserPrivacySetting> get_user_privacy_setting(MutableSlice setting) {
+    setting = trim(setting);
+    to_lower_inplace(setting);
+    if (setting == "invite") {
+      return make_tl_object<td_api::userPrivacySettingAllowChatInvites>();
+    }
+    if (setting == "status") {
+      return make_tl_object<td_api::userPrivacySettingShowStatus>();
+    }
+    if (setting == "call") {
+      return make_tl_object<td_api::userPrivacySettingAllowCalls>();
+    }
+    return nullptr;
+  }
+
+  static tl_object_ptr<td_api::SearchMessagesFilter> get_search_messages_filter(MutableSlice filter) {
+    filter = trim(filter);
+    to_lower_inplace(filter);
+    if (filter == "an" || filter == "animation") {
+      return make_tl_object<td_api::searchMessagesFilterAnimation>();
+    }
+    if (filter == "au" || filter == "audio") {
+      return make_tl_object<td_api::searchMessagesFilterAudio>();
+    }
+    if (filter == "d" || filter == "document") {
+      return make_tl_object<td_api::searchMessagesFilterDocument>();
+    }
+    if (filter == "p" || filter == "photo") {
+      return make_tl_object<td_api::searchMessagesFilterPhoto>();
+    }
+    if (filter == "vi" || filter == "video") {
+      return make_tl_object<td_api::searchMessagesFilterVideo>();
+    }
+    if (filter == "vo" || filter == "voice") {
+      return make_tl_object<td_api::searchMessagesFilterVoiceNote>();
+    }
+    if (filter == "pvo") {
+      return make_tl_object<td_api::searchMessagesFilterPhotoAndVideo>();
+    }
+    if (filter == "u" || filter == "url") {
+      return make_tl_object<td_api::searchMessagesFilterUrl>();
+    }
+    if (filter == "cp" || filter == "chatphoto") {
+      return make_tl_object<td_api::searchMessagesFilterChatPhoto>();
+    }
+    if (filter == "vc" || filter == "call") {
+      return make_tl_object<td_api::searchMessagesFilterCall>();
+    }
+    if (filter == "mvc" || filter == "missedcall") {
+      return make_tl_object<td_api::searchMessagesFilterMissedCall>();
+    }
+    if (filter == "vn" || filter == "videonote") {
+      return make_tl_object<td_api::searchMessagesFilterVideoNote>();
+    }
+    if (filter == "vvn" || filter == "voicevideonote") {
+      return make_tl_object<td_api::searchMessagesFilterVoiceAndVideoNote>();
+    }
+    if (filter == "m" || filter == "mention") {
+      return make_tl_object<td_api::searchMessagesFilterMention>();
+    }
+    if (filter == "um" || filter == "umention") {
+      return make_tl_object<td_api::searchMessagesFilterUnreadMention>();
+    }
+    if (!filter.empty()) {
+      LOG(ERROR) << "Unsupported message filter " << filter;
+    }
+    return nullptr;
+  }
+
+  tl_object_ptr<td_api::TopChatCategory> get_top_chat_category(MutableSlice category) {
+    category = trim(category);
+    to_lower_inplace(category);
+    if (!category.empty() && category.back() == 's') {
+      category.remove_suffix(1);
+    }
+    if (category == "bot") {
+      return make_tl_object<td_api::topChatCategoryBots>();
+    } else if (category == "group") {
+      return make_tl_object<td_api::topChatCategoryGroups>();
+    } else if (category == "channel") {
+      return make_tl_object<td_api::topChatCategoryChannels>();
+    } else if (category == "inline") {
+      return make_tl_object<td_api::topChatCategoryInlineBots>();
+    } else if (category == "call") {
+      return make_tl_object<td_api::topChatCategoryCalls>();
+    } else {
+      return make_tl_object<td_api::topChatCategoryUsers>();
+    }
+  }
+
+  static tl_object_ptr<td_api::ChatAction> get_chat_action(MutableSlice action) {
+    action = trim(action);
+    to_lower_inplace(action);
+    if (action == "c" || action == "cancel") {
+      return make_tl_object<td_api::chatActionCancel>();
+    }
+    if (action == "rvi" || action == "record_video") {
+      return make_tl_object<td_api::chatActionRecordingVideo>();
+    }
+    if (action == "uvi" || action == "upload_video") {
+      return make_tl_object<td_api::chatActionUploadingVideo>(50);
+    }
+    if (action == "rvo" || action == "record_voice") {
+      return make_tl_object<td_api::chatActionRecordingVoiceNote>();
+    }
+    if (action == "uvo" || action == "upload_voice") {
+      return make_tl_object<td_api::chatActionUploadingVoiceNote>(50);
+    }
+    if (action == "up" || action == "upload_photo") {
+      return make_tl_object<td_api::chatActionUploadingPhoto>(50);
+    }
+    if (action == "ud" || action == "upload_document") {
+      return make_tl_object<td_api::chatActionUploadingDocument>(50);
+    }
+    if (action == "fl" || action == "find_location") {
+      return make_tl_object<td_api::chatActionChoosingLocation>();
+    }
+    if (action == "cc" || action == "choose_contact") {
+      return make_tl_object<td_api::chatActionChoosingContact>();
+    }
+    if (action == "spg" || action == "start_play_game") {
+      return make_tl_object<td_api::chatActionStartPlayingGame>();
+    }
+    if (action == "rvn" || action == "record_video_note") {
+      return make_tl_object<td_api::chatActionRecordingVideoNote>();
+    }
+    if (action == "uvn" || action == "upload_video_note") {
+      return make_tl_object<td_api::chatActionUploadingVideoNote>(50);
+    }
+    return make_tl_object<td_api::chatActionTyping>();
+  }
+
+  static tl_object_ptr<td_api::NetworkType> get_network_type(MutableSlice type) {
+    type = trim(type);
+    to_lower_inplace(type);
+    if (type == "none") {
+      return make_tl_object<td_api::networkTypeNone>();
+    }
+    if (type == "mobile") {
+      return make_tl_object<td_api::networkTypeMobile>();
+    }
+    if (type == "roaming") {
+      return make_tl_object<td_api::networkTypeMobileRoaming>();
+    }
+    if (type == "wifi") {
+      return make_tl_object<td_api::networkTypeWiFi>();
+    }
+    if (type == "other") {
+      return make_tl_object<td_api::networkTypeOther>();
+    }
+    return nullptr;
+  }
+
+  static td_api::object_ptr<td_api::Object> execute(tl_object_ptr<td_api::Function> f) {
+    LOG(INFO) << "Execute request: " << to_string(f);
+    auto res = ClientActor::execute(std::move(f));
+    LOG(INFO) << "Execute response: " << to_string(res);
+    return res;
+  }
+
+  uint64 send_request(tl_object_ptr<td_api::Function> f) {
+    static uint64 query_num = 1;
+    if (!td_.empty()) {
+      auto id = query_num++;
+      send_closure_later(td_, &ClientActor::request, id, std::move(f));
+      return id;
+    } else {
+      LOG(ERROR) << "Failed to send: " << to_string(f);
+      return 0;
+    }
+  }
+
+  void send_message(const string &chat_id, tl_object_ptr<td_api::InputMessageContent> &&input_message_content,
+                    bool disable_notification = false, bool from_background = false, int64 reply_to_message_id = 0) {
+    auto chat = as_chat_id(chat_id);
+    auto id = send_request(make_tl_object<td_api::sendMessage>(
+        chat, reply_to_message_id, disable_notification, from_background, nullptr, std::move(input_message_content)));
+    query_id_to_send_message_info_[id].start_time = Time::now();
+  }
+
+  void on_cmd(string cmd) {
+    // TODO: need to remove https://en.wikipedia.org/wiki/ANSI_escape_code from cmd
+    cmd.erase(std::remove_if(cmd.begin(), cmd.end(), [](char c) { return 0 <= c && c < 32; }), cmd.end());
+    LOG(INFO) << "CMD:[" << cmd << "]";
+
+    string op;
+    string args;
+    std::tie(op, args) = split(cmd);
+
+    const int32 OP_BLOCK_COUNT = 5;
+    int32 op_not_found_count = 0;
+
+    if (op == "gas") {
+      send_request(make_tl_object<td_api::getAuthorizationState>());
+    } else if (op == "sap") {
+      send_request(make_tl_object<td_api::setAuthenticationPhoneNumber>(args, false, false));
+    } else if (op == "rac") {
+      send_request(make_tl_object<td_api::resendAuthenticationCode>());
+    } else if (op == "cdek" || op == "CheckDatabaseEncryptionKey") {
+      send_request(make_tl_object<td_api::checkDatabaseEncryptionKey>(args));
+    } else if (op == "sdek" || op == "SetDatabaseEncryptionKey") {
+      send_request(make_tl_object<td_api::setDatabaseEncryptionKey>(args));
+    } else if (op == "cac") {
+      string code;
+      string first_name;
+      string last_name;
+
+      std::tie(code, args) = split(args);
+      std::tie(first_name, last_name) = split(args);
+
+      send_request(make_tl_object<td_api::checkAuthenticationCode>(code, first_name, last_name));
+    } else if (op == "cap") {
+      send_request(make_tl_object<td_api::checkAuthenticationPassword>(args));
+    } else if (op == "cab") {
+      send_request(make_tl_object<td_api::checkAuthenticationBotToken>(args));
+    } else if (op == "rapr") {
+      send_request(make_tl_object<td_api::requestAuthenticationPasswordRecovery>());
+    } else if (op == "rap") {
+      send_request(make_tl_object<td_api::recoverAuthenticationPassword>(args));
+    } else if (op == "lo" || op == "LogOut" || op == "logout") {
+      send_request(make_tl_object<td_api::logOut>());
+    } else if (op == "ra" || op == "destroy") {
+      send_request(make_tl_object<td_api::destroy>());
+    } else if (op == "reset") {
+      init_td();
+    } else if (op == "close_td") {
+      send_request(make_tl_object<td_api::close>());
+    } else if (op == "DeleteAccountYesIReallyWantToDeleteMyAccount") {
+      send_request(make_tl_object<td_api::deleteAccount>(args));
+    } else if (op == "gps" || op == "GetPasswordState") {
+      send_request(make_tl_object<td_api::getPasswordState>());
+    } else if (op == "spass" || op == "SetPassword") {
+      string password;
+      string new_password;
+      string new_hint;
+      string recovery_email_address;
+      std::tie(password, args) = split(args);
+      if (password == "#") {
+        password = "";
+      }
+      std::tie(new_password, args) = split(args);
+      if (new_password == "#") {
+        new_password = "";
+      }
+      std::tie(new_hint, args) = split(args);
+      if (new_hint == "#") {
+        new_hint = "";
+      }
+      recovery_email_address = args;
+      if (recovery_email_address == "#") {
+        recovery_email_address = "";
+      }
+      send_request(make_tl_object<td_api::setPassword>(password, new_password, new_hint, true, recovery_email_address));
+    } else if (op == "srea" || op == "SetRecoveryEmailAddress") {
+      string password;
+      string recovery_email_address;
+      std::tie(password, recovery_email_address) = split(args);
+      send_request(make_tl_object<td_api::setRecoveryEmailAddress>(password, recovery_email_address));
+    } else if (op == "rpr" || op == "RequestPasswordRecovery") {
+      send_request(make_tl_object<td_api::requestPasswordRecovery>());
+    } else if (op == "rp" || op == "RecoverPassword") {
+      send_request(make_tl_object<td_api::recoverPassword>(args));
+    } else if (op == "grea" || op == "GetRecoveryEmailAddress") {
+      send_request(make_tl_object<td_api::getRecoveryEmailAddress>(args));
+    } else if (op == "gtp" || op == "GetTemporaryPassword") {
+      send_request(make_tl_object<td_api::getTemporaryPasswordState>());
+    } else if (op == "ctp" || op == "CreateTemporaryPassword") {
+      send_request(make_tl_object<td_api::createTemporaryPassword>(args, 60 * 6));
+    } else if (op == "pdu" || op == "processDcUpdate") {
+      string dc_id;
+      string ip_port;
+      std::tie(dc_id, ip_port) = split(args);
+      send_request(make_tl_object<td_api::processDcUpdate>(dc_id, ip_port));
+    } else if (op == "rda") {
+      send_request(make_tl_object<td_api::registerDevice>(make_tl_object<td_api::deviceTokenApplePush>(args, true),
+                                                          as_user_ids("")));
+    } else if (op == "rdb") {
+      send_request(make_tl_object<td_api::registerDevice>(make_tl_object<td_api::deviceTokenBlackBerryPush>(args),
+                                                          as_user_ids("")));
+    } else if (op == "rdt") {
+      string token;
+      string other_user_ids_str;
+
+      std::tie(token, other_user_ids_str) = split(args);
+      send_request(make_tl_object<td_api::registerDevice>(make_tl_object<td_api::deviceTokenTizenPush>(token),
+                                                          as_user_ids(other_user_ids_str)));
+    } else if (op == "rdu") {
+      string token;
+      string other_user_ids_str;
+
+      std::tie(token, other_user_ids_str) = split(args);
+      send_request(make_tl_object<td_api::registerDevice>(make_tl_object<td_api::deviceTokenUbuntuPush>(token),
+                                                          as_user_ids(other_user_ids_str)));
+    } else if (op == "rdw") {
+      string endpoint;
+      string key;
+      string secret;
+      string other_user_ids_str;
+
+      std::tie(endpoint, args) = split(args);
+      std::tie(key, args) = split(args);
+      std::tie(secret, other_user_ids_str) = split(args);
+      send_request(make_tl_object<td_api::registerDevice>(
+          make_tl_object<td_api::deviceTokenWebPush>(endpoint, key, secret), as_user_ids(other_user_ids_str)));
+    } else if (op == "gpf") {
+      string chat_id;
+      string message_id;
+
+      std::tie(chat_id, message_id) = split(args);
+      send_request(make_tl_object<td_api::getPaymentForm>(as_chat_id(chat_id), as_message_id(message_id)));
+    } else if (op == "voi") {
+      string chat_id;
+      string message_id;
+      string allow_save;
+
+      std::tie(chat_id, args) = split(args);
+      std::tie(message_id, allow_save) = split(args);
+      send_request(make_tl_object<td_api::validateOrderInfo>(as_chat_id(chat_id), as_message_id(message_id), nullptr,
+                                                             as_bool(allow_save)));
+    } else if (op == "spfs") {
+      string chat_id;
+      string message_id;
+      string order_info_id;
+      string shipping_option_id;
+      string saved_credentials_id;
+
+      std::tie(chat_id, args) = split(args);
+      std::tie(message_id, args) = split(args);
+      std::tie(order_info_id, args) = split(args);
+      std::tie(shipping_option_id, saved_credentials_id) = split(args);
+      send_request(make_tl_object<td_api::sendPaymentForm>(
+          as_chat_id(chat_id), as_message_id(message_id), order_info_id, shipping_option_id,
+          make_tl_object<td_api::inputCredentialsSaved>(saved_credentials_id)));
+    } else if (op == "spfn") {
+      string chat_id;
+      string message_id;
+      string order_info_id;
+      string shipping_option_id;
+      string data;
+
+      std::tie(chat_id, args) = split(args);
+      std::tie(message_id, args) = split(args);
+      std::tie(order_info_id, args) = split(args);
+      std::tie(shipping_option_id, data) = split(args);
+      send_request(make_tl_object<td_api::sendPaymentForm>(as_chat_id(chat_id), as_message_id(message_id),
+                                                           order_info_id, shipping_option_id,
+                                                           make_tl_object<td_api::inputCredentialsNew>(data, true)));
+    } else if (op == "gpre") {
+      string chat_id;
+      string message_id;
+
+      std::tie(chat_id, message_id) = split(args);
+      send_request(make_tl_object<td_api::getPaymentReceipt>(as_chat_id(chat_id), as_message_id(message_id)));
+    } else if (op == "gsoi") {
+      send_request(make_tl_object<td_api::getSavedOrderInfo>());
+    } else if (op == "dsoi") {
+      send_request(make_tl_object<td_api::deleteSavedOrderInfo>());
+    } else if (op == "dsc") {
+      send_request(make_tl_object<td_api::deleteSavedCredentials>());
+    } else if (op == "gpr") {
+      send_request(make_tl_object<td_api::getUserPrivacySettingRules>(get_user_privacy_setting(args)));
+    } else if (op == "spr") {
+      string setting;
+      string allow;
+      std::tie(setting, allow) = split(args);
+
+      std::vector<tl_object_ptr<td_api::UserPrivacySettingRule>> rules;
+      if (as_bool(allow)) {
+        rules.push_back(make_tl_object<td_api::userPrivacySettingRuleAllowAll>());
+      } else {
+        rules.push_back(make_tl_object<td_api::userPrivacySettingRuleRestrictAll>());
+      }
+      send_request(make_tl_object<td_api::setUserPrivacySettingRules>(
+          get_user_privacy_setting(setting), make_tl_object<td_api::userPrivacySettingRules>(std::move(rules))));
+    } else if (op == "cp" || op == "ChangePhone") {
+      send_request(make_tl_object<td_api::changePhoneNumber>(args, false, false));
+    } else if (op == "ccpc" || op == "CheckChangePhoneCode") {
+      send_request(make_tl_object<td_api::checkChangePhoneNumberCode>(args));
+    } else if (op == "rcpc" || op == "ResendChangePhoneCode") {
+      send_request(make_tl_object<td_api::resendChangePhoneNumberCode>());
+    } else if (op == "GetContacts") {
+      auto limit = to_integer<int32>(args);
+      if (limit == 0) {
+        limit = 10000;
+      }
+      send_request(make_tl_object<td_api::searchContacts>("", limit));
+    } else if (op == "ImportContacts") {
+      vector<string> contacts_str = full_split(args, ';');
+      vector<tl_object_ptr<td_api::contact>> contacts;
+      for (auto c : contacts_str) {
+        string phone_number;
+        string first_name;
+        string last_name;
+        std::tie(phone_number, c) = split(c, ',');
+        std::tie(first_name, last_name) = split(c, ',');
+        contacts.push_back(make_tl_object<td_api::contact>(phone_number, first_name, last_name, 0));
+      }
+
+      send_request(make_tl_object<td_api::importContacts>(std::move(contacts)));
+    } else if (op == "RemoveContacts") {
+      send_request(make_tl_object<td_api::removeContacts>(as_user_ids(args)));
+    } else if (op == "gicc") {
+      send_request(make_tl_object<td_api::getImportedContactCount>());
+    } else if (op == "cic") {
+      vector<string> contacts_str = full_split(args, ';');
+      vector<tl_object_ptr<td_api::contact>> contacts;
+      for (auto c : contacts_str) {
+        string phone_number;
+        string first_name;
+        string last_name;
+        std::tie(phone_number, c) = split(c, ',');
+        std::tie(first_name, last_name) = split(c, ',');
+        contacts.push_back(make_tl_object<td_api::contact>(phone_number, first_name, last_name, 0));
+      }
+
+      send_request(make_tl_object<td_api::changeImportedContacts>(std::move(contacts)));
+    } else if (op == "ClearImportedContacts") {
+      send_request(make_tl_object<td_api::clearImportedContacts>());
+    } else {
+      op_not_found_count++;
+    }
+
+    if (op == "gc" || op == "GetChats") {
+      string offset_order_string;
+      string offset_chat_id;
+      string limit;
+
+      std::tie(limit, args) = split(args);
+      std::tie(offset_order_string, offset_chat_id) = split(args);
+
+      if (limit.empty()) {
+        limit = "10000";
+      }
+      int64 offset_order;
+      if (offset_order_string.empty()) {
+        offset_order = std::numeric_limits<int64>::max();
+      } else {
+        offset_order = to_integer<int64>(offset_order_string);
+      }
+      send_request(
+          make_tl_object<td_api::getChats>(offset_order, as_chat_id(offset_chat_id), to_integer<int32>(limit)));
+    } else if (op == "gcc" || op == "GetCommonChats") {
+      string user_id;
+      string offset_chat_id;
+      string limit;
+
+      std::tie(user_id, args) = split(args);
+      std::tie(offset_chat_id, limit) = split(args);
+
+      if (limit.empty()) {
+        limit = "100";
+      }
+      send_request(make_tl_object<td_api::getGroupsInCommon>(as_user_id(user_id), as_chat_id(offset_chat_id),
+                                                             to_integer<int32>(limit)));
+    } else if (op == "gh" || op == "GetHistory" || op == "ghl") {
+      string chat_id;
+      string from_message_id;
+      string offset;
+      string limit;
+
+      std::tie(chat_id, args) = split(args);
+      std::tie(from_message_id, args) = split(args);
+      if (from_message_id.empty()) {
+        from_message_id = "0";
+      }
+      std::tie(offset, args) = split(args);
+      if (offset.empty()) {
+        offset = "0";
+      }
+      std::tie(limit, args) = split(args);
+      if (limit.empty()) {
+        limit = "10";
+      }
+      if (!args.empty()) {
+        LOG(ERROR) << "Wrong parameters to function getChatHistory specified";
+      } else {
+        send_request(make_tl_object<td_api::getChatHistory>(as_chat_id(chat_id), as_message_id(from_message_id),
+                                                            to_integer<int32>(offset), to_integer<int32>(limit),
+                                                            op == "ghl"));
+      }
+    } else if (op == "ghf") {
+      get_history_chat_id = as_chat_id(args);
+
+      send_request(make_tl_object<td_api::getChatHistory>(get_history_chat_id, std::numeric_limits<int64>::max(), 0,
+                                                          100, false));
+    } else if (op == "spvf") {
+      search_chat_id = as_chat_id(args);
+
+      send_request(make_tl_object<td_api::searchChatMessages>(
+          search_chat_id, "", 0, 0, 0, 100, make_tl_object<td_api::searchMessagesFilterPhotoAndVideo>()));
+    } else if (op == "Search") {
+      string from_date;
+      string limit;
+      string query;
+
+      std::tie(query, args) = split(args);
+      std::tie(limit, from_date) = split(args);
+      if (from_date.empty()) {
+        from_date = "0";
+      }
+      send_request(make_tl_object<td_api::searchMessages>(query, to_integer<int32>(from_date), 2147482647, 0,
+                                                          to_integer<int32>(limit)));
+    } else if (op == "SCM") {
+      string chat_id;
+      string limit;
+      string query;
+
+      std::tie(chat_id, args) = split(args);
+      std::tie(limit, query) = split(args);
+      if (limit.empty()) {
+        limit = "10";
+      }
+
+      send_request(make_tl_object<td_api::searchChatMessages>(as_chat_id(chat_id), query, 0, 0, 0,
+                                                              to_integer<int32>(limit), nullptr));
+    } else if (op == "SMME") {
+      string chat_id;
+      string limit;
+
+      std::tie(chat_id, limit) = split(args);
+      if (limit.empty()) {
+        limit = "10";
+      }
+
+      send_request(make_tl_object<td_api::searchChatMessages>(as_chat_id(chat_id), "", my_id_, 0, 0,
+                                                              to_integer<int32>(limit), nullptr));
+    } else if (op == "SM") {
+      string chat_id;
+      string offset_message_id;
+      string offset;
+      string limit;
+      string filter;
+
+      std::tie(chat_id, args) = split(args);
+      std::tie(filter, args) = split(args);
+      std::tie(limit, args) = split(args);
+      std::tie(offset_message_id, offset) = split(args);
+      if (limit.empty()) {
+        limit = "10";
+      }
+      if (offset_message_id.empty()) {
+        offset_message_id = "0";
+      }
+      if (offset.empty()) {
+        offset = "0";
+      }
+
+      send_request(make_tl_object<td_api::searchChatMessages>(
+          as_chat_id(chat_id), "", 0, as_message_id(offset_message_id), to_integer<int32>(offset),
+          to_integer<int32>(limit), get_search_messages_filter(filter)));
+    } else if (op == "SC") {
+      string limit;
+      string offset_message_id;
+      string only_missed;
+
+      std::tie(limit, args) = split(args);
+      std::tie(offset_message_id, only_missed) = split(args);
+      if (limit.empty()) {
+        limit = "10";
+      }
+      if (offset_message_id.empty()) {
+        offset_message_id = "0";
+      }
+
+      send_request(make_tl_object<td_api::searchCallMessages>(as_message_id(offset_message_id),
+                                                              to_integer<int32>(limit), as_bool(only_missed)));
+    } else if (op == "SCRLM") {
+      string chat_id;
+      string limit;
+
+      std::tie(chat_id, limit) = split(args);
+      if (limit.empty()) {
+        limit = "10";
+      }
+
+      send_request(
+          make_tl_object<td_api::searchChatRecentLocationMessages>(as_chat_id(chat_id), to_integer<int32>(limit)));
+    } else if (op == "SearchAudio") {
+      string chat_id;
+      string offset_message_id;
+      string limit;
+      string query;
+
+      std::tie(chat_id, args) = split(args);
+      std::tie(offset_message_id, args) = split(args);
+      if (offset_message_id.empty()) {
+        offset_message_id = "0";
+      }
+      std::tie(limit, query) = split(args);
+      if (limit.empty()) {
+        limit = "10";
+      }
+      send_request(make_tl_object<td_api::searchChatMessages>(
+          as_chat_id(chat_id), query, 0, as_message_id(offset_message_id), 0, to_integer<int32>(limit),
+          make_tl_object<td_api::searchMessagesFilterAudio>()));
+    } else if (op == "SearchDocument") {
+      string chat_id;
+      string offset_message_id;
+      string limit;
+      string query;
+
+      std::tie(chat_id, args) = split(args);
+      std::tie(offset_message_id, args) = split(args);
+      if (offset_message_id.empty()) {
+        offset_message_id = "0";
+      }
+      std::tie(limit, query) = split(args);
+      if (limit.empty()) {
+        limit = "10";
+      }
+      send_request(make_tl_object<td_api::searchChatMessages>(
+          as_chat_id(chat_id), query, 0, to_integer<int64>(offset_message_id), 0, to_integer<int32>(limit),
+          make_tl_object<td_api::searchMessagesFilterDocument>()));
+    } else if (op == "SearchPhoto") {
+      string chat_id;
+      string offset_message_id;
+      string limit;
+      string query;
+
+      std::tie(chat_id, args) = split(args);
+      std::tie(offset_message_id, args) = split(args);
+      if (offset_message_id.empty()) {
+        offset_message_id = "2000000000000000000";
+      }
+      std::tie(limit, query) = split(args);
+      if (limit.empty()) {
+        limit = "10";
+      }
+      send_request(make_tl_object<td_api::searchChatMessages>(
+          as_chat_id(chat_id), query, 0, as_message_id(offset_message_id), 0, to_integer<int32>(limit),
+          make_tl_object<td_api::searchMessagesFilterPhoto>()));
+    } else if (op == "SearchChatPhoto") {
+      string chat_id;
+      string offset_message_id;
+      string limit;
+      string query;
+
+      std::tie(chat_id, args) = split(args);
+      std::tie(offset_message_id, args) = split(args);
+      if (offset_message_id.empty()) {
+        offset_message_id = "2000000000000000000";
+      }
+      std::tie(limit, query) = split(args);
+      if (limit.empty()) {
+        limit = "10";
+      }
+      send_request(make_tl_object<td_api::searchChatMessages>(
+          as_chat_id(chat_id), query, 0, as_message_id(offset_message_id), 0, to_integer<int32>(limit),
+          make_tl_object<td_api::searchMessagesFilterChatPhoto>()));
+    } else if (op == "gup" || op == "GetUserPhotos") {
+      string user_id;
+      string offset;
+      string limit;
+
+      std::tie(user_id, args) = split(args);
+      std::tie(offset, args) = split(args);
+      if (offset.empty()) {
+        offset = "0";
+      }
+      std::tie(limit, args) = split(args);
+      if (limit.empty()) {
+        limit = "10";
+      }
+      if (!args.empty()) {
+        LOG(ERROR) << "Wrong parameters to function getUserProfilePhotos specified";
+      } else {
+        send_request(make_tl_object<td_api::getUserProfilePhotos>(as_user_id(user_id), to_integer<int32>(offset),
+                                                                  to_integer<int32>(limit)));
+      }
+    } else if (op == "dcrm") {
+      string chat_id;
+      string message_id;
+
+      std::tie(chat_id, message_id) = split(args);
+      send_request(make_tl_object<td_api::deleteChatReplyMarkup>(as_chat_id(chat_id), as_message_id(message_id)));
+    } else if (op == "go") {
+      send_request(make_tl_object<td_api::getOption>(args));
+    } else if (op == "sob") {
+      string name;
+      string value;
+
+      std::tie(name, value) = split(args);
+      send_request(make_tl_object<td_api::setOption>(name, make_tl_object<td_api::optionValueBoolean>(as_bool(value))));
+    } else if (op == "soe") {
+      send_request(make_tl_object<td_api::setOption>(args, make_tl_object<td_api::optionValueEmpty>()));
+    } else if (op == "soi") {
+      string name;
+      string value;
+
+      std::tie(name, value) = split(args);
+      int32 value_int = to_integer<int32>(value);
+      send_request(make_tl_object<td_api::setOption>(name, make_tl_object<td_api::optionValueInteger>(value_int)));
+    } else if (op == "sos") {
+      string name;
+      string value;
+
+      std::tie(name, value) = split(args);
+      send_request(make_tl_object<td_api::setOption>(name, make_tl_object<td_api::optionValueString>(value)));
+    } else if (op == "me") {
+      send_request(make_tl_object<td_api::getMe>());
+    } else if (op == "sattl") {
+      send_request(make_tl_object<td_api::setAccountTtl>(make_tl_object<td_api::accountTtl>(to_integer<int32>(args))));
+    } else if (op == "gattl") {
+      send_request(make_tl_object<td_api::getAccountTtl>());
+    } else if (op == "GetActiveSessions") {
+      send_request(make_tl_object<td_api::getActiveSessions>());
+    } else if (op == "TerminateSession") {
+      send_request(make_tl_object<td_api::terminateSession>(to_integer<int64>(args)));
+    } else if (op == "TerminateAllOtherSessions") {
+      send_request(make_tl_object<td_api::terminateAllOtherSessions>());
+    } else if (op == "gcw") {
+      send_request(make_tl_object<td_api::getConnectedWebsites>());
+    } else if (op == "dw") {
+      send_request(make_tl_object<td_api::disconnectWebsite>(to_integer<int64>(args)));
+    } else if (op == "daw") {
+      send_request(make_tl_object<td_api::disconnectAllWebsites>());
+    } else if (op == "gw") {
+      send_request(make_tl_object<td_api::getWallpapers>());
+    } else if (op == "gccode") {
+      send_request(make_tl_object<td_api::getCountryCode>());
+    } else if (op == "git") {
+      send_request(make_tl_object<td_api::getInviteText>());
+    } else if (op == "gtos") {
+      send_request(make_tl_object<td_api::getTermsOfService>());
+    } else if (op == "tme") {
+      send_request(make_tl_object<td_api::getRecentlyVisitedTMeUrls>(args));
+    } else if (op == "bu") {
+      send_request(make_tl_object<td_api::blockUser>(as_user_id(args)));
+    } else if (op == "ubu") {
+      send_request(make_tl_object<td_api::unblockUser>(as_user_id(args)));
+    } else if (op == "gbu") {
+      string offset;
+      string limit;
+
+      std::tie(offset, limit) = split(args);
+      if (offset.empty()) {
+        offset = "0";
+      }
+      if (limit.empty()) {
+        limit = "10";
+      }
+      send_request(make_tl_object<td_api::getBlockedUsers>(to_integer<int32>(offset), to_integer<int32>(limit)));
+    } else if (op == "gu") {
+      send_request(make_tl_object<td_api::getUser>(as_user_id(args)));
+    } else if (op == "gsu") {
+      send_request(make_tl_object<td_api::getSupportUser>());
+    } else if (op == "gs") {
+      string limit;
+      string emoji;
+      std::tie(limit, emoji) = split(args);
+      send_request(make_tl_object<td_api::getStickers>(emoji, to_integer<int32>(limit)));
+    } else if (op == "sst") {
+      string limit;
+      string emoji;
+      std::tie(limit, emoji) = split(args);
+      send_request(make_tl_object<td_api::searchStickers>(emoji, to_integer<int32>(limit)));
+    } else if (op == "gss") {
+      send_request(make_tl_object<td_api::getStickerSet>(to_integer<int64>(args)));
+    } else if (op == "giss") {
+      send_request(make_tl_object<td_api::getInstalledStickerSets>(as_bool(args)));
+    } else if (op == "gass") {
+      string is_masks;
+      string offset_sticker_set_id;
+      string limit;
+
+      std::tie(is_masks, args) = split(args);
+      std::tie(offset_sticker_set_id, limit) = split(args);
+
+      send_request(make_tl_object<td_api::getArchivedStickerSets>(
+          as_bool(is_masks), to_integer<int64>(offset_sticker_set_id), to_integer<int32>(limit)));
+    } else if (op == "gtss") {
+      send_request(make_tl_object<td_api::getTrendingStickerSets>());
+    } else if (op == "gatss") {
+      send_request(make_tl_object<td_api::getAttachedStickerSets>(to_integer<int32>(args)));
+    } else if (op == "storage") {
+      send_request(make_tl_object<td_api::getStorageStatistics>(to_integer<int32>(args)));
+    } else if (op == "storage_fast") {
+      send_request(make_tl_object<td_api::getStorageStatisticsFast>());
+    } else if (op == "optimize_storage") {
+      string chat_ids;
+      string exclude_chat_ids;
+      string chat_ids_limit;
+      std::tie(chat_ids, args) = split(args);
+      std::tie(exclude_chat_ids, chat_ids_limit) = split(args);
+      send_request(make_tl_object<td_api::optimizeStorage>(
+          10000000, -1, -1, 0, std::vector<tl_object_ptr<td_api::FileType>>(), as_chat_ids(chat_ids, ','),
+          as_chat_ids(exclude_chat_ids, ','), to_integer<int32>(chat_ids_limit)));
+    } else if (op == "clean_storage_default") {
+      send_request(make_tl_object<td_api::optimizeStorage>());
+    } else if (op == "clean_storage") {
+      std::vector<tl_object_ptr<td_api::FileType>> types;
+      types.push_back(make_tl_object<td_api::fileTypeThumbnail>());
+      types.push_back(make_tl_object<td_api::fileTypeProfilePhoto>());
+      types.push_back(make_tl_object<td_api::fileTypePhoto>());
+      types.push_back(make_tl_object<td_api::fileTypeVoiceNote>());
+      types.push_back(make_tl_object<td_api::fileTypeVideo>());
+      types.push_back(make_tl_object<td_api::fileTypeDocument>());
+      types.push_back(make_tl_object<td_api::fileTypeSecret>());
+      types.push_back(make_tl_object<td_api::fileTypeUnknown>());
+      types.push_back(make_tl_object<td_api::fileTypeSticker>());
+      types.push_back(make_tl_object<td_api::fileTypeAudio>());
+      types.push_back(make_tl_object<td_api::fileTypeAnimation>());
+      types.push_back(make_tl_object<td_api::fileTypeVideoNote>());
+      send_request(make_tl_object<td_api::optimizeStorage>(0, -1, -1, 0, std::move(types), as_chat_ids(args, ','),
+                                                           as_chat_ids(""), 20));
+    } else if (op == "network") {
+      send_request(make_tl_object<td_api::getNetworkStatistics>());
+    } else if (op == "current_network") {
+      send_request(make_tl_object<td_api::getNetworkStatistics>(true));
+    } else if (op == "reset_network") {
+      send_request(make_tl_object<td_api::resetNetworkStatistics>());
+    } else if (op == "snt") {
+      send_request(make_tl_object<td_api::setNetworkType>(get_network_type(args)));
+    } else if (op == "ansc") {
+      string sent_bytes;
+      string received_bytes;
+      string duration;
+      string network_type;
+      std::tie(sent_bytes, args) = split(args);
+      std::tie(received_bytes, args) = split(args);
+      std::tie(duration, network_type) = split(args);
+      send_request(make_tl_object<td_api::addNetworkStatistics>(make_tl_object<td_api::networkStatisticsEntryCall>(
+          get_network_type(network_type), to_integer<int32>(sent_bytes), to_integer<int32>(received_bytes),
+          to_double(duration))));
+    } else if (op == "ans") {
+      string sent_bytes;
+      string received_bytes;
+      string network_type;
+      std::tie(sent_bytes, args) = split(args);
+      std::tie(received_bytes, network_type) = split(args);
+      send_request(make_tl_object<td_api::addNetworkStatistics>(make_tl_object<td_api::networkStatisticsEntryFile>(
+          make_tl_object<td_api::fileTypeDocument>(), get_network_type(network_type), to_integer<int32>(sent_bytes),
+          to_integer<int32>(received_bytes))));
+    } else if (op == "top_chats") {
+      send_request(make_tl_object<td_api::getTopChats>(get_top_chat_category(args), 50));
+    } else if (op == "rtc") {
+      string chat_id;
+      string category;
+      std::tie(chat_id, category) = split(args);
+
+      send_request(make_tl_object<td_api::removeTopChat>(get_top_chat_category(category), as_chat_id(chat_id)));
+    } else if (op == "sss") {
+      send_request(make_tl_object<td_api::searchStickerSet>(args));
+    } else if (op == "siss") {
+      send_request(make_tl_object<td_api::searchInstalledStickerSets>(false, args, 2));
+    } else if (op == "ssss") {
+      send_request(make_tl_object<td_api::searchStickerSets>(args));
+    } else if (op == "css") {
+      string set_id;
+      string is_installed;
+      string is_archived;
+
+      std::tie(set_id, args) = split(args);
+      std::tie(is_installed, is_archived) = split(args);
+
+      send_request(make_tl_object<td_api::changeStickerSet>(to_integer<int64>(set_id), as_bool(is_installed),
+                                                            as_bool(is_archived)));
+    } else if (op == "vtss") {
+      send_request(make_tl_object<td_api::viewTrendingStickerSets>(to_integers<int64>(args)));
+    } else if (op == "riss") {
+      string is_masks;
+      string new_order;
+
+      std::tie(is_masks, new_order) = split(args);
+
+      send_request(
+          make_tl_object<td_api::reorderInstalledStickerSets>(as_bool(is_masks), to_integers<int64>(new_order)));
+    } else if (op == "grs") {
+      send_request(make_tl_object<td_api::getRecentStickers>(as_bool(args)));
+    } else if (op == "ars") {
+      string is_attached;
+      string sticker_id;
+
+      std::tie(is_attached, sticker_id) = split(args);
+
+      send_request(make_tl_object<td_api::addRecentSticker>(as_bool(is_attached), as_input_file_id(sticker_id)));
+    } else if (op == "rrs") {
+      string is_attached;
+      string sticker_id;
+
+      std::tie(is_attached, sticker_id) = split(args);
+
+      send_request(make_tl_object<td_api::removeRecentSticker>(as_bool(is_attached), as_input_file_id(sticker_id)));
+    } else if (op == "gfs") {
+      send_request(make_tl_object<td_api::getFavoriteStickers>());
+    } else if (op == "afs") {
+      send_request(make_tl_object<td_api::addFavoriteSticker>(as_input_file_id(args)));
+    } else if (op == "rfs") {
+      send_request(make_tl_object<td_api::removeFavoriteSticker>(as_input_file_id(args)));
+    } else if (op == "crs") {
+      send_request(make_tl_object<td_api::clearRecentStickers>(as_bool(args)));
+    } else if (op == "gse") {
+      send_request(make_tl_object<td_api::getStickerEmojis>(as_input_file_id(args)));
+    } else {
+      op_not_found_count++;
+    }
+
+    if (op == "gsan") {
+      send_request(make_tl_object<td_api::getSavedAnimations>());
+    } else if (op == "asan") {
+      send_request(make_tl_object<td_api::addSavedAnimation>(as_input_file_id(args)));
+    } else if (op == "rsan") {
+      send_request(make_tl_object<td_api::removeSavedAnimation>(as_input_file_id(args)));
+    } else if (op == "guf") {
+      send_request(make_tl_object<td_api::getUserFullInfo>(as_user_id(args)));
+    } else if (op == "gbg") {
+      send_request(make_tl_object<td_api::getBasicGroup>(to_integer<int32>(args)));
+    } else if (op == "gbgf") {
+      send_request(make_tl_object<td_api::getBasicGroupFullInfo>(to_integer<int32>(args)));
+    } else if (op == "gsg" || op == "gch") {
+      send_request(make_tl_object<td_api::getSupergroup>(to_integer<int32>(args)));
+    } else if (op == "gsgf" || op == "gchf") {
+      send_request(make_tl_object<td_api::getSupergroupFullInfo>(to_integer<int32>(args)));
+    } else if (op == "gsc") {
+      send_request(make_tl_object<td_api::getSecretChat>(to_integer<int32>(args)));
+    } else if (op == "scm") {
+      string chat_id;
+      string limit;
+      string query;
+
+      std::tie(chat_id, args) = split(args);
+      std::tie(limit, query) = split(args);
+      send_request(make_tl_object<td_api::searchChatMembers>(as_chat_id(chat_id), query, to_integer<int32>(limit)));
+    } else if (op == "gcm") {
+      string chat_id;
+      string user_id;
+
+      std::tie(chat_id, user_id) = split(args);
+      send_request(make_tl_object<td_api::getChatMember>(as_chat_id(chat_id), as_user_id(user_id)));
+    } else if (op == "GetSupergroupAdministrators") {
+      string supergroup_id;
+      string offset;
+      string limit;
+
+      std::tie(supergroup_id, args) = split(args);
+      std::tie(offset, limit) = split(args);
+      if (offset.empty()) {
+        offset = "0";
+      }
+      if (limit.empty()) {
+        limit = "10";
+      }
+      send_request(make_tl_object<td_api::getSupergroupMembers>(
+          to_integer<int32>(supergroup_id), make_tl_object<td_api::supergroupMembersFilterAdministrators>(),
+          to_integer<int32>(offset), to_integer<int32>(limit)));
+    } else if (op == "GetChatAdministrators") {
+      string chat_id = args;
+      send_request(make_tl_object<td_api::getChatAdministrators>(as_chat_id(chat_id)));
+    } else if (op == "GetSupergroupBanned") {
+      string supergroup_id;
+      string query;
+      string offset;
+      string limit;
+
+      std::tie(supergroup_id, args) = split(args);
+      std::tie(query, args) = split(args);
+      std::tie(offset, limit) = split(args);
+      if (offset.empty()) {
+        offset = "0";
+      }
+      if (limit.empty()) {
+        limit = "10";
+      }
+      send_request(make_tl_object<td_api::getSupergroupMembers>(
+          to_integer<int32>(supergroup_id), make_tl_object<td_api::supergroupMembersFilterBanned>(query),
+          to_integer<int32>(offset), to_integer<int32>(limit)));
+    } else if (op == "GetSupergroupBots") {
+      string supergroup_id;
+      string offset;
+      string limit;
+
+      std::tie(supergroup_id, args) = split(args);
+      std::tie(offset, limit) = split(args);
+      if (offset.empty()) {
+        offset = "0";
+      }
+      if (limit.empty()) {
+        limit = "10";
+      }
+      send_request(make_tl_object<td_api::getSupergroupMembers>(to_integer<int32>(supergroup_id),
+                                                                make_tl_object<td_api::supergroupMembersFilterBots>(),
+                                                                to_integer<int32>(offset), to_integer<int32>(limit)));
+    } else if (op == "GetSupergroupMembers") {
+      string supergroup_id;
+      string offset;
+      string limit;
+
+      std::tie(supergroup_id, args) = split(args);
+      std::tie(offset, limit) = split(args);
+      if (offset.empty()) {
+        offset = "0";
+      }
+      if (limit.empty()) {
+        limit = "10";
+      }
+      send_request(make_tl_object<td_api::getSupergroupMembers>(to_integer<int32>(supergroup_id),
+                                                                make_tl_object<td_api::supergroupMembersFilterRecent>(),
+                                                                to_integer<int32>(offset), to_integer<int32>(limit)));
+    } else if (op == "SearchSupergroupMembers") {
+      string supergroup_id;
+      string query;
+      string offset;
+      string limit;
+
+      std::tie(supergroup_id, args) = split(args);
+      std::tie(query, args) = split(args);
+      std::tie(offset, limit) = split(args);
+      if (offset.empty()) {
+        offset = "0";
+      }
+      if (limit.empty()) {
+        limit = "10";
+      }
+      send_request(make_tl_object<td_api::getSupergroupMembers>(
+          to_integer<int32>(supergroup_id), make_tl_object<td_api::supergroupMembersFilterSearch>(query),
+          to_integer<int32>(offset), to_integer<int32>(limit)));
+    } else if (op == "GetSupergroupRestricted") {
+      string supergroup_id;
+      string query;
+      string offset;
+      string limit;
+
+      std::tie(supergroup_id, args) = split(args);
+      std::tie(query, args) = split(args);
+      std::tie(offset, limit) = split(args);
+      if (offset.empty()) {
+        offset = "0";
+      }
+      if (limit.empty()) {
+        limit = "10";
+      }
+      send_request(make_tl_object<td_api::getSupergroupMembers>(
+          to_integer<int32>(supergroup_id), make_tl_object<td_api::supergroupMembersFilterRestricted>(query),
+          to_integer<int32>(offset), to_integer<int32>(limit)));
+    } else if (op == "gdialog" || op == "gd") {
+      send_request(make_tl_object<td_api::getChat>(as_chat_id(args)));
+    } else if (op == "open") {
+      send_request(make_tl_object<td_api::openChat>(as_chat_id(args)));
+    } else if (op == "close") {
+      send_request(make_tl_object<td_api::closeChat>(as_chat_id(args)));
+    } else if (op == "gm") {
+      string chat_id;
+      string message_id;
+      std::tie(chat_id, message_id) = split(args);
+      send_request(make_tl_object<td_api::getMessage>(as_chat_id(chat_id), as_message_id(message_id)));
+    } else if (op == "grm") {
+      string chat_id;
+      string message_id;
+      std::tie(chat_id, message_id) = split(args);
+      send_request(make_tl_object<td_api::getRepliedMessage>(as_chat_id(chat_id), as_message_id(message_id)));
+    } else if (op == "gcpm") {
+      string chat_id = args;
+      send_request(make_tl_object<td_api::getChatPinnedMessage>(as_chat_id(chat_id)));
+    } else if (op == "gms") {
+      string chat_id;
+      string message_ids;
+      std::tie(chat_id, message_ids) = split(args);
+      send_request(make_tl_object<td_api::getMessages>(as_chat_id(chat_id), as_message_ids(message_ids)));
+    } else if (op == "gpml") {
+      string chat_id;
+      string message_id;
+      string for_album;
+      std::tie(chat_id, args) = split(args);
+      std::tie(message_id, for_album) = split(args);
+      send_request(make_tl_object<td_api::getPublicMessageLink>(as_chat_id(chat_id), as_message_id(message_id),
+                                                                as_bool(for_album)));
+    } else if (op == "gcmbd") {
+      string chat_id;
+      string date;
+      std::tie(chat_id, date) = split(args);
+      send_request(make_tl_object<td_api::getChatMessageByDate>(as_chat_id(chat_id), to_integer<int32>(date)));
+    } else if (op == "gf" || op == "GetFile") {
+      send_request(make_tl_object<td_api::getFile>(as_file_id(args)));
+    } else if (op == "grf") {
+      send_request(make_tl_object<td_api::getRemoteFile>(args, nullptr));
+    } else if (op == "df" || op == "DownloadFile") {
+      string file_id;
+      string priority;
+      std::tie(file_id, priority) = split(args);
+      if (priority.empty()) {
+        priority = "1";
+      }
+
+      send_request(make_tl_object<td_api::downloadFile>(as_file_id(file_id), to_integer<int32>(priority)));
+    } else if (op == "dff") {
+      string file_id;
+      string priority;
+      std::tie(file_id, priority) = split(args);
+      if (priority.empty()) {
+        priority = "1";
+      }
+
+      for (int i = 1; i <= as_file_id(file_id); i++) {
+        send_request(make_tl_object<td_api::downloadFile>(i, to_integer<int32>(priority)));
+      }
+    } else if (op == "cdf") {
+      send_request(make_tl_object<td_api::cancelDownloadFile>(as_file_id(args), true));
+    } else if (op == "uf") {
+      string file_path;
+      string priority;
+      std::tie(file_path, priority) = split(args);
+      if (priority.empty()) {
+        priority = "1";
+      }
+
+      send_request(make_tl_object<td_api::uploadFile>(as_local_file(file_path), make_tl_object<td_api::fileTypePhoto>(),
+                                                      to_integer<int32>(priority)));
+    } else if (op == "ufs") {
+      string file_path;
+      string priority;
+      std::tie(file_path, priority) = split(args);
+      if (priority.empty()) {
+        priority = "1";
+      }
+
+      send_request(make_tl_object<td_api::uploadFile>(
+          as_local_file(file_path), make_tl_object<td_api::fileTypeSecret>(), to_integer<int32>(priority)));
+    } else if (op == "ufg") {
+      string file_path;
+      string conversion;
+      std::tie(file_path, conversion) = split(args);
+      send_request(make_tl_object<td_api::uploadFile>(as_generated_file(file_path, conversion),
+                                                      make_tl_object<td_api::fileTypePhoto>(), 1));
+    } else if (op == "cuf") {
+      send_request(make_tl_object<td_api::cancelUploadFile>(as_file_id(args)));
+    } else if (op == "delf" || op == "DeleteFile") {
+      string file_id = args;
+      send_request(make_tl_object<td_api::deleteFile>(as_file_id(file_id)));
+    } else if (op == "dm") {
+      string chat_id;
+      string message_ids;
+      string revoke;
+      std::tie(chat_id, args) = split(args);
+      std::tie(message_ids, revoke) = split(args);
+
+      send_request(make_tl_object<td_api::deleteMessages>(as_chat_id(chat_id), as_message_ids(message_ids, ','),
+                                                          as_bool(revoke)));
+    } else if (op == "fm" || op == "fmg") {
+      string chat_id;
+      string from_chat_id;
+      string message_ids;
+      std::tie(chat_id, args) = split(args);
+      std::tie(from_chat_id, message_ids) = split(args);
+
+      auto chat = as_chat_id(chat_id);
+      send_request(make_tl_object<td_api::forwardMessages>(chat, as_chat_id(from_chat_id), as_message_ids(message_ids),
+                                                           false, false, op == "fmg"));
+    } else if (op == "csc" || op == "CreateSecretChat") {
+      send_request(make_tl_object<td_api::createSecretChat>(to_integer<int32>(args)));
+    } else if (op == "cnsc" || op == "CreateNewSecretChat") {
+      send_request(make_tl_object<td_api::createNewSecretChat>(as_user_id(args)));
+    } else if (op == "scstn") {
+      send_request(make_tl_object<td_api::sendChatScreenshotTakenNotification>(as_chat_id(args)));
+    } else if (op == "sscttl" || op == "setSecretChatTtl") {
+      string chat_id;
+      string ttl;
+      std::tie(chat_id, ttl) = split(args);
+
+      send_request(make_tl_object<td_api::sendChatSetTtlMessage>(as_chat_id(chat_id), to_integer<int32>(ttl)));
+    } else if (op == "closeSC" || op == "cancelSC") {
+      send_request(make_tl_object<td_api::closeSecretChat>(to_integer<int32>(args)));
+    } else if (op == "cc" || op == "CreateCall") {
+      send_request(make_tl_object<td_api::createCall>(as_user_id(args),
+                                                      make_tl_object<td_api::callProtocol>(true, true, 65, 65)));
+    } else if (op == "dc" || op == "DiscardCall") {
+      string call_id;
+      string is_disconnected;
+      std::tie(call_id, is_disconnected) = split(args);
+
+      send_request(make_tl_object<td_api::discardCall>(as_call_id(call_id), as_bool(is_disconnected), 0, 0));
+    } else if (op == "ac" || op == "AcceptCall") {
+      send_request(make_tl_object<td_api::acceptCall>(as_call_id(args),
+                                                      make_tl_object<td_api::callProtocol>(true, true, 65, 65)));
+    } else if (op == "scr" || op == "SendCallRating") {
+      send_request(make_tl_object<td_api::sendCallRating>(as_call_id(args), 5, "Wow, such good call! (TDLib test)"));
+    } else if (op == "scdi" || op == "SendCallDebugInformation") {
+      send_request(make_tl_object<td_api::sendCallDebugInformation>(as_call_id(args), "{}"));
+    } else if (op == "gcil") {
+      send_request(make_tl_object<td_api::generateChatInviteLink>(as_chat_id(args)));
+    } else if (op == "ccil") {
+      send_request(make_tl_object<td_api::checkChatInviteLink>(args));
+    } else if (op == "jcbil") {
+      send_request(make_tl_object<td_api::joinChatByInviteLink>(args));
+    } else if (op == "gte") {
+      send_request(make_tl_object<td_api::getTextEntities>(args));
+    } else if (op == "gtes") {
+      execute(make_tl_object<td_api::getTextEntities>(args));
+    } else if (op == "pte") {
+      send_request(make_tl_object<td_api::parseTextEntities>(args, make_tl_object<td_api::textParseModeMarkdown>()));
+    } else if (op == "ptes") {
+      execute(make_tl_object<td_api::parseTextEntities>(args, make_tl_object<td_api::textParseModeMarkdown>()));
+    } else if (op == "gfmt") {
+      send_request(make_tl_object<td_api::getFileMimeType>(trim(args)));
+    } else if (op == "gfe") {
+      send_request(make_tl_object<td_api::getFileExtension>(trim(args)));
+    } else {
+      op_not_found_count++;
+    }
+
+    if (op == "scdm") {
+      string chat_id;
+      string reply_to_message_id;
+      string message;
+      std::tie(chat_id, args) = split(args);
+      std::tie(reply_to_message_id, message) = split(args);
+      tl_object_ptr<td_api::draftMessage> draft_message;
+      if (!reply_to_message_id.empty() || !message.empty()) {
+        vector<tl_object_ptr<td_api::textEntity>> entities;
+        entities.push_back(make_tl_object<td_api::textEntity>(0, 1, make_tl_object<td_api::textEntityTypePre>()));
+
+        draft_message = make_tl_object<td_api::draftMessage>(
+            as_message_id(reply_to_message_id),
+            make_tl_object<td_api::inputMessageText>(
+                make_tl_object<td_api::formattedText>(message, std::move(entities)), true, false));
+      }
+      send_request(make_tl_object<td_api::setChatDraftMessage>(as_chat_id(chat_id), std::move(draft_message)));
+    } else if (op == "tcip") {
+      string chat_id;
+      string is_pinned;
+      std::tie(chat_id, is_pinned) = split(args);
+      send_request(make_tl_object<td_api::toggleChatIsPinned>(as_chat_id(chat_id), as_bool(is_pinned)));
+    } else if (op == "spchats") {
+      vector<string> chat_ids_str = full_split(args, ' ');
+      vector<int64> chat_ids;
+      for (auto &chat_id_str : chat_ids_str) {
+        chat_ids.push_back(as_chat_id(chat_id_str));
+      }
+      send_request(make_tl_object<td_api::setPinnedChats>(std::move(chat_ids)));
+    } else if (op == "sca") {
+      string chat_id;
+      string action;
+      std::tie(chat_id, action) = split(args);
+      send_request(make_tl_object<td_api::sendChatAction>(as_chat_id(chat_id), get_chat_action(action)));
+    } else if (op == "smt" || op == "smtp" || op == "smtf" || op == "smtpf") {
+      const string &chat_id = args;
+      for (int i = 1; i <= 200; i++) {
+        string message = PSTRING() << "#" << i;
+        if (i == 6 || (op.back() == 'f' && i % 2 == 0)) {
+          message = string(4097, 'a');
+        }
+        if (op[3] == 'p') {
+          send_message(chat_id, make_tl_object<td_api::inputMessagePhoto>(as_local_file("rgb.jpg"), nullptr, Auto(), 0,
+                                                                          0, as_caption(message), 0));
+        } else {
+          send_message(chat_id,
+                       make_tl_object<td_api::inputMessageText>(
+                           make_tl_object<td_api::formattedText>(message, vector<tl_object_ptr<td_api::textEntity>>()),
+                           false, true));
+        }
+      }
+    } else if (op == "ssm") {
+      string chat_id;
+      string from_search_id;
+      string limit;
+      string filter;
+      string query;
+
+      std::tie(chat_id, args) = split(args);
+      std::tie(from_search_id, args) = split(args);
+      std::tie(limit, args) = split(args);
+      std::tie(filter, query) = split(args);
+
+      send_request(
+          make_tl_object<td_api::searchSecretMessages>(as_chat_id(chat_id), query, to_integer<int64>(from_search_id),
+                                                       to_integer<int32>(limit), get_search_messages_filter(filter)));
+    } else if (op == "sm" || op == "sms" || op == "smr" || op == "smf") {
+      string chat_id;
+      string reply_to_message_id;
+      string message;
+
+      std::tie(chat_id, message) = split(args);
+      if (op == "smr") {
+        std::tie(reply_to_message_id, message) = split(message);
+      }
+      if (op == "smf") {
+        message = string(1000097, 'a');
+      }
+
+      auto parsed_text =
+          execute(make_tl_object<td_api::parseTextEntities>(message, make_tl_object<td_api::textParseModeMarkdown>()));
+      if (parsed_text->get_id() == td_api::error::ID) {
+        parsed_text = make_tl_object<td_api::formattedText>(message, vector<tl_object_ptr<td_api::textEntity>>());
+      }
+
+      send_message(
+          chat_id,
+          make_tl_object<td_api::inputMessageText>(move_tl_object_as<td_api::formattedText>(parsed_text), false, true),
+          op == "sms", false, as_message_id(reply_to_message_id));
+    } else if (op == "smap" || op == "smapr") {
+      string chat_id;
+      string reply_to_message_id;
+      vector<string> photos;
+
+      std::tie(chat_id, args) = split(args);
+      if (op == "smapr") {
+        std::tie(reply_to_message_id, args) = split(args);
+      }
+      photos = full_split(args);
+
+      send_request(make_tl_object<td_api::sendMessageAlbum>(
+          as_chat_id(chat_id), as_message_id(reply_to_message_id), false, false,
+          transform(photos, [](const string &photo_path) {
+            tl_object_ptr<td_api::InputMessageContent> content = make_tl_object<td_api::inputMessagePhoto>(
+                as_local_file(photo_path), nullptr, Auto(), 0, 0, as_caption(""), 0);
+            return content;
+          })));
+    } else if (op == "em") {
+      string chat_id;
+      string message_id;
+      string message;
+      std::tie(chat_id, args) = split(args);
+      std::tie(message_id, message) = split(args);
+      send_request(make_tl_object<td_api::editMessageText>(
+          as_chat_id(chat_id), as_message_id(message_id), nullptr,
+          make_tl_object<td_api::inputMessageText>(
+              make_tl_object<td_api::formattedText>(message, vector<tl_object_ptr<td_api::textEntity>>()), true,
+              true)));
+    } else if (op == "emll") {
+      string chat_id;
+      string message_id;
+      string latitude;
+      string longitude;
+      std::tie(chat_id, args) = split(args);
+      std::tie(message_id, args) = split(args);
+      std::tie(latitude, longitude) = split(args);
+      send_request(make_tl_object<td_api::editMessageLiveLocation>(as_chat_id(chat_id), as_message_id(message_id),
+                                                                   nullptr, as_location(latitude, longitude)));
+    } else if (op == "gallm") {
+      send_request(make_tl_object<td_api::getActiveLiveLocationMessages>());
+    } else if (op == "sbsm") {
+      string bot_id;
+      string chat_id;
+      string parameter;
+      std::tie(bot_id, args) = split(args);
+      std::tie(chat_id, parameter) = split(args);
+      send_request(make_tl_object<td_api::sendBotStartMessage>(as_user_id(bot_id), as_chat_id(chat_id), parameter));
+    } else if (op == "giqr") {
+      string bot_id;
+      string query;
+      std::tie(bot_id, query) = split(args);
+      send_request(make_tl_object<td_api::getInlineQueryResults>(as_user_id(bot_id), 0, nullptr, query, ""));
+    } else if (op == "giqro") {
+      string bot_id;
+      string offset;
+      string query;
+      std::tie(bot_id, args) = split(args);
+      std::tie(offset, query) = split(args);
+      send_request(make_tl_object<td_api::getInlineQueryResults>(as_user_id(bot_id), 0, nullptr, query, offset));
+    } else if (op == "giqrl") {
+      string bot_id;
+      string query;
+      std::tie(bot_id, query) = split(args);
+      send_request(
+          make_tl_object<td_api::getInlineQueryResults>(as_user_id(bot_id), 0, as_location("1.1", "2.2"), query, ""));
+    } else if (op == "siqr") {
+      string chat_id;
+      string query_id;
+      string result_id;
+      std::tie(chat_id, args) = split(args);
+      std::tie(query_id, result_id) = split(args);
+
+      auto chat = as_chat_id(chat_id);
+      send_request(make_tl_object<td_api::sendInlineQueryResultMessage>(chat, 0, false, false,
+                                                                        to_integer<int64>(query_id), result_id));
+    } else if (op == "gcqr") {
+      string chat_id;
+      string message_id;
+      string data;
+      std::tie(chat_id, args) = split(args);
+      std::tie(message_id, data) = split(args);
+      send_request(make_tl_object<td_api::getCallbackQueryAnswer>(
+          as_chat_id(chat_id), as_message_id(message_id), make_tl_object<td_api::callbackQueryPayloadData>(data)));
+    } else if (op == "gcgqr") {
+      string chat_id;
+      string message_id;
+      std::tie(chat_id, message_id) = split(args);
+      send_request(make_tl_object<td_api::getCallbackQueryAnswer>(
+          as_chat_id(chat_id), as_message_id(message_id), make_tl_object<td_api::callbackQueryPayloadGame>("")));
+    } else if (op == "san") {
+      string chat_id;
+      string animation_path;
+      string width;
+      string height;
+      string caption;
+      std::tie(chat_id, args) = split(args);
+      std::tie(animation_path, args) = split(args);
+      std::tie(width, args) = split(args);
+      std::tie(height, caption) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessageAnimation>(
+                                as_local_file(animation_path), nullptr, 60, to_integer<int32>(width),
+                                to_integer<int32>(height), as_caption(caption)));
+    } else if (op == "sang") {
+      string chat_id;
+      string animation_path;
+      string animation_conversion;
+      std::tie(chat_id, args) = split(args);
+      std::tie(animation_path, animation_conversion) = split(args);
+      send_message(chat_id,
+                   make_tl_object<td_api::inputMessageAnimation>(
+                       as_generated_file(animation_path, animation_conversion), nullptr, 60, 0, 0, as_caption("")));
+    } else if (op == "sanid") {
+      string chat_id;
+      string file_id;
+      std::tie(chat_id, file_id) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessageAnimation>(as_input_file_id(file_id), nullptr, 0, 0, 0,
+                                                                          as_caption("")));
+    } else if (op == "sanurl") {
+      string chat_id;
+      string url;
+      std::tie(chat_id, url) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessageAnimation>(
+                                td_api::make_object<td_api::inputFileGenerated>(url, "#url#", 0), nullptr, 0, 0, 0,
+                                as_caption("")));
+    } else if (op == "sanurl2") {
+      string chat_id;
+      string url;
+      std::tie(chat_id, url) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessageAnimation>(
+                                td_api::make_object<td_api::inputFileRemote>(url), nullptr, 0, 0, 0, as_caption("")));
+    } else if (op == "sau") {
+      string chat_id;
+      string audio_path;
+      string duration;
+      string title;
+      string performer;
+      std::tie(chat_id, args) = split(args);
+      std::tie(audio_path, args) = split(args);
+      std::tie(duration, args) = split(args);
+      std::tie(title, performer) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessageAudio>(as_local_file(audio_path), nullptr,
+                                                                      to_integer<int32>(duration), title, performer,
+                                                                      as_caption("audio caption")));
+    } else if (op == "svoice") {
+      string chat_id;
+      string voice_path;
+      std::tie(chat_id, voice_path) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessageVoiceNote>(as_local_file(voice_path), 0, "abacaba",
+                                                                          as_caption("voice caption")));
+    } else if (op == "SendContact" || op == "scontact") {
+      string chat_id;
+      string phone_number;
+      string first_name;
+      string last_name;
+      string user_id;
+      std::tie(chat_id, args) = split(args);
+      std::tie(phone_number, args) = split(args);
+      std::tie(first_name, args) = split(args);
+      std::tie(last_name, user_id) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessageContact>(make_tl_object<td_api::contact>(
+                                phone_number, first_name, last_name, as_user_id(user_id))));
+    } else if (op == "sf") {
+      string chat_id;
+      string from_chat_id;
+      string from_message_id;
+      std::tie(chat_id, args) = split(args);
+      std::tie(from_chat_id, from_message_id) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessageForwarded>(as_chat_id(from_chat_id),
+                                                                          as_message_id(from_message_id), true));
+    } else if (op == "sd") {
+      string chat_id;
+      string document_path;
+      std::tie(chat_id, document_path) = split(args);
+      send_message(chat_id, make_tl_object<td_api::inputMessageDocument>(
+                                as_local_file(document_path), nullptr,
+                                as_caption(u8"\u1680\u180Etest \u180E\n\u180E\n\u180E\n cap\ttion\u180E\u180E")));
+    } else if (op == "sdt") {
+      string chat_id;
+      string document_path;
+      string thumbnail_path;
+      std::tie(chat_id, args) = split(args);
+      std::tie(document_path, thumbnail_path) = split(args);
+      send_message(chat_id, make_tl_object<td_api::inputMessageDocument>(
+                                as_local_file(document_path),
+                                make_tl_object<td_api::inputThumbnail>(as_local_file(thumbnail_path), 0, 0),
+                                as_caption("test caption")));
+    } else if (op == "sdg") {
+      string chat_id;
+      string document_path;
+      string document_conversion;
+      std::tie(chat_id, args) = split(args);
+      std::tie(document_path, document_conversion) = split(args);
+      send_message(chat_id,
+                   make_tl_object<td_api::inputMessageDocument>(as_generated_file(document_path, document_conversion),
+                                                                nullptr, as_caption("test caption")));
+    } else if (op == "sdtg") {
+      string chat_id;
+      string document_path;
+      string thumbnail_path;
+      string thumbnail_conversion;
+      std::tie(chat_id, args) = split(args);
+      std::tie(document_path, args) = split(args);
+      std::tie(thumbnail_path, thumbnail_conversion) = split(args);
+      send_message(chat_id, make_tl_object<td_api::inputMessageDocument>(
+                                as_local_file(document_path),
+                                make_tl_object<td_api::inputThumbnail>(
+                                    as_generated_file(thumbnail_path, thumbnail_conversion), 0, 0),
+                                as_caption("test caption")));
+    } else if (op == "sdgtg") {
+      string chat_id;
+      string document_path;
+      string document_conversion;
+      string thumbnail_path;
+      string thumbnail_conversion;
+      std::tie(chat_id, args) = split(args);
+      std::tie(document_path, args) = split(args);
+      std::tie(document_conversion, args) = split(args);
+      std::tie(thumbnail_path, thumbnail_conversion) = split(args);
+      send_message(chat_id, make_tl_object<td_api::inputMessageDocument>(
+                                as_generated_file(document_path, document_conversion),
+                                make_tl_object<td_api::inputThumbnail>(
+                                    as_generated_file(thumbnail_path, thumbnail_conversion), 0, 0),
+                                as_caption("test caption")));
+    } else if (op == "sdid") {
+      string chat_id;
+      string file_id;
+      std::tie(chat_id, file_id) = split(args);
+      send_message(chat_id,
+                   make_tl_object<td_api::inputMessageDocument>(as_input_file_id(file_id), nullptr, as_caption("")));
+    } else if (op == "sg") {
+      string chat_id;
+      string bot_user_id;
+      string game_short_name;
+      std::tie(chat_id, args) = split(args);
+      std::tie(bot_user_id, game_short_name) = split(args);
+      send_message(chat_id, make_tl_object<td_api::inputMessageGame>(as_user_id(bot_user_id), game_short_name));
+    } else if (op == "sl") {
+      string chat_id;
+      std::tie(chat_id, args) = split(args);
+
+      string latitude;
+      string longitude;
+      std::tie(latitude, longitude) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessageLocation>(as_location(latitude, longitude), 0));
+    } else if (op == "sll") {
+      string chat_id;
+      string period;
+      string latitude;
+      string longitude;
+      std::tie(chat_id, args) = split(args);
+      std::tie(period, args) = split(args);
+      std::tie(latitude, longitude) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessageLocation>(as_location(latitude, longitude),
+                                                                         to_integer<int32>(period)));
+    } else if (op == "sp") {
+      string chat_id;
+      string photo_path;
+      string sticker_file_ids_str;
+      vector<int32> sticker_file_ids;
+      std::tie(chat_id, args) = split(args);
+      std::tie(sticker_file_ids_str, photo_path) = split(args);
+      if (trim(photo_path).empty()) {
+        photo_path = sticker_file_ids_str;
+      } else {
+        sticker_file_ids = to_integers<int32>(sticker_file_ids_str, ',');
+      }
+
+      send_message(chat_id,
+                   make_tl_object<td_api::inputMessagePhoto>(as_local_file(photo_path), nullptr,
+                                                             std::move(sticker_file_ids), 0, 0, as_caption(""), 0));
+    } else if (op == "spttl") {
+      string chat_id;
+      string photo_path;
+      std::tie(chat_id, photo_path) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessagePhoto>(as_local_file(photo_path), nullptr, Auto(), 0, 0,
+                                                                      as_caption(""), 10));
+    } else if (op == "spg") {
+      string chat_id;
+      string photo_path;
+      string conversion;
+      std::tie(chat_id, args) = split(args);
+      std::tie(photo_path, conversion) = split(args);
+
+      send_message(chat_id,
+                   make_tl_object<td_api::inputMessagePhoto>(as_generated_file(photo_path, conversion), nullptr,
+                                                             vector<int32>(), 0, 0, as_caption(""), 0));
+    } else if (op == "spt") {
+      string chat_id;
+      string photo_path;
+      string thumbnail_path;
+      std::tie(chat_id, args) = split(args);
+      std::tie(photo_path, thumbnail_path) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessagePhoto>(
+                                as_local_file(photo_path),
+                                make_tl_object<td_api::inputThumbnail>(as_local_file(thumbnail_path), 90, 89),
+                                vector<int32>(), 0, 0, as_caption(""), 0));
+    } else if (op == "sptg") {
+      string chat_id;
+      string photo_path;
+      string thumbnail_path;
+      string thumbnail_conversion;
+      std::tie(chat_id, args) = split(args);
+      std::tie(photo_path, args) = split(args);
+      std::tie(thumbnail_path, thumbnail_conversion) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessagePhoto>(
+                                as_local_file(photo_path),
+                                make_tl_object<td_api::inputThumbnail>(
+                                    as_generated_file(thumbnail_path, thumbnail_conversion), 90, 89),
+                                vector<int32>(), 0, 0, as_caption(""), 0));
+    } else if (op == "spgtg") {
+      string chat_id;
+      string photo_path;
+      string conversion;
+      string thumbnail_path;
+      string thumbnail_conversion;
+
+      std::tie(chat_id, args) = split(args);
+      std::tie(photo_path, args) = split(args);
+      std::tie(conversion, args) = split(args);
+      std::tie(thumbnail_path, thumbnail_conversion) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessagePhoto>(
+                                as_generated_file(photo_path, conversion),
+                                make_tl_object<td_api::inputThumbnail>(
+                                    as_generated_file(thumbnail_path, thumbnail_conversion), 90, 89),
+                                vector<int32>(), 0, 0, as_caption(""), 0));
+    } else if (op == "spid") {
+      string chat_id;
+      string file_id;
+      std::tie(chat_id, file_id) = split(args);
+      send_message(chat_id, make_tl_object<td_api::inputMessagePhoto>(as_input_file_id(file_id), nullptr,
+                                                                      vector<int32>(), 0, 0, as_caption(""), 0));
+    } else if (op == "ss") {
+      string chat_id;
+      string sticker_path;
+      std::tie(chat_id, sticker_path) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessageSticker>(as_local_file(sticker_path), nullptr, 0, 0));
+    } else if (op == "ssid") {
+      string chat_id;
+      string file_id;
+      std::tie(chat_id, file_id) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessageSticker>(as_input_file_id(file_id), nullptr, 0, 0));
+    } else if (op == "sv") {
+      string chat_id;
+      string video_path;
+      string sticker_file_ids_str;
+      vector<int32> sticker_file_ids;
+      std::tie(chat_id, args) = split(args);
+      std::tie(sticker_file_ids_str, video_path) = split(args);
+      if (trim(video_path).empty()) {
+        video_path = sticker_file_ids_str;
+      } else {
+        sticker_file_ids = to_integers<int32>(sticker_file_ids_str, ',');
+      }
+
+      send_message(chat_id, make_tl_object<td_api::inputMessageVideo>(as_local_file(video_path), nullptr,
+                                                                      std::move(sticker_file_ids), 1, 2, 3, true,
+                                                                      as_caption(""), 0));
+    } else if (op == "svn") {
+      string chat_id;
+      string video_path;
+      std::tie(chat_id, video_path) = split(args);
+      send_message(chat_id, make_tl_object<td_api::inputMessageVideoNote>(as_local_file(video_path), nullptr, 1, 5));
+    } else if (op == "svenue") {
+      string chat_id;
+
+      string latitude;
+      string longitude;
+      string title;
+      string address;
+      string provider;
+      string venue_id;
+      std::tie(chat_id, args) = split(args);
+      std::tie(latitude, args) = split(args);
+      std::tie(longitude, args) = split(args);
+      std::tie(title, args) = split(args);
+      std::tie(address, args) = split(args);
+      std::tie(provider, venue_id) = split(args);
+
+      send_message(chat_id, make_tl_object<td_api::inputMessageVenue>(make_tl_object<td_api::venue>(
+                                as_location(latitude, longitude), title, address, provider, venue_id)));
+    } else if (op == "test") {
+      send_request(make_tl_object<td_api::testNetwork>());
+    } else if (op == "alarm") {
+      send_request(make_tl_object<td_api::setAlarm>(to_double(args)));
+    } else if (op == "delete") {
+      string chat_id;
+      string remove_from_the_chat_list;
+      std::tie(chat_id, remove_from_the_chat_list) = split(args);
+      send_request(make_tl_object<td_api::deleteChatHistory>(as_chat_id(chat_id), as_bool(remove_from_the_chat_list)));
+    } else if (op == "dmfu") {
+      string chat_id;
+      string user_id;
+      std::tie(chat_id, user_id) = split(args);
+      send_request(make_tl_object<td_api::deleteChatMessagesFromUser>(as_chat_id(chat_id), as_user_id(user_id)));
+    } else if (op == "cnbgc") {
+      string user_ids_string;
+      string title;
+      std::tie(user_ids_string, title) = split(args);
+
+      send_request(make_tl_object<td_api::createNewBasicGroupChat>(as_user_ids(user_ids_string, ','), title));
+    } else if (op == "cnch") {
+      send_request(make_tl_object<td_api::createNewSupergroupChat>(args, true, "Description"));
+    } else if (op == "cnsg") {
+      send_request(make_tl_object<td_api::createNewSupergroupChat>(args, false, "Description"));
+    } else if (op == "UpgradeBasicGroupChatToSupergroupChat") {
+      send_request(make_tl_object<td_api::upgradeBasicGroupChatToSupergroupChat>(as_chat_id(args)));
+    } else if (op == "DeleteSupergroup") {
+      send_request(make_tl_object<td_api::deleteSupergroup>(to_integer<int32>(args)));
+    } else if (op == "gcpc") {
+      send_request(make_tl_object<td_api::getCreatedPublicChats>());
+    } else if (op == "cpc") {
+      string user_id;
+      string force;
+
+      std::tie(user_id, force) = split(args);
+      send_request(make_tl_object<td_api::createPrivateChat>(as_user_id(user_id), as_bool(force)));
+    } else if (op == "cbgc") {
+      string basic_group_id;
+      string force;
+
+      std::tie(basic_group_id, force) = split(args);
+      send_request(make_tl_object<td_api::createBasicGroupChat>(to_integer<int32>(basic_group_id), as_bool(force)));
+    } else if (op == "csgc" || op == "cchc") {
+      string supergroup_id;
+      string force;
+
+      std::tie(supergroup_id, force) = split(args);
+      send_request(make_tl_object<td_api::createSupergroupChat>(to_integer<int32>(supergroup_id), as_bool(force)));
+    } else if (op == "sct") {
+      string chat_id;
+      string title;
+
+      std::tie(chat_id, title) = split(args);
+      send_request(make_tl_object<td_api::setChatTitle>(as_chat_id(chat_id), title));
+    } else if (op == "scp") {
+      string chat_id;
+      string photo_path;
+
+      std::tie(chat_id, photo_path) = split(args);
+      send_request(make_tl_object<td_api::setChatPhoto>(as_chat_id(chat_id), as_local_file(photo_path)));
+    } else if (op == "scpid") {
+      string chat_id;
+      string file_id;
+
+      std::tie(chat_id, file_id) = split(args);
+      send_request(make_tl_object<td_api::setChatPhoto>(as_chat_id(chat_id), as_input_file_id(file_id)));
+    } else if (op == "sccd") {
+      string chat_id;
+      string client_data;
+
+      std::tie(chat_id, client_data) = split(args);
+      send_request(make_tl_object<td_api::setChatClientData>(as_chat_id(chat_id), client_data));
+    } else if (op == "acm") {
+      string chat_id;
+      string user_id;
+      string forward_limit;
+
+      std::tie(chat_id, args) = split(args);
+      std::tie(user_id, forward_limit) = split(args);
+      send_request(make_tl_object<td_api::addChatMember>(as_chat_id(chat_id), as_user_id(user_id),
+                                                         to_integer<int32>(forward_limit)));
+    } else if (op == "acms") {
+      string chat_id;
+      string user_ids;
+
+      std::tie(chat_id, user_ids) = split(args);
+      send_request(make_tl_object<td_api::addChatMembers>(as_chat_id(chat_id), as_user_ids(user_ids, ',')));
+    } else {
+      op_not_found_count++;
+    }
+
+    if (op == "scms") {
+      string chat_id;
+      string user_id;
+      string status_str;
+      tl_object_ptr<td_api::ChatMemberStatus> status;
+
+      std::tie(chat_id, args) = split(args);
+      std::tie(user_id, status_str) = split(args);
+      if (status_str == "member") {
+        status = make_tl_object<td_api::chatMemberStatusMember>();
+      } else if (status_str == "left") {
+        status = make_tl_object<td_api::chatMemberStatusLeft>();
+      } else if (status_str == "banned") {
+        status = make_tl_object<td_api::chatMemberStatusBanned>(std::numeric_limits<int32>::max());
+      } else if (status_str == "creator") {
+        status = make_tl_object<td_api::chatMemberStatusCreator>(true);
+      } else if (status_str == "uncreator") {
+        status = make_tl_object<td_api::chatMemberStatusCreator>(false);
+      } else if (status_str == "admin") {
+        status =
+            make_tl_object<td_api::chatMemberStatusAdministrator>(true, true, true, true, true, true, true, true, true);
+      } else if (status_str == "unadmin") {
+        status = make_tl_object<td_api::chatMemberStatusAdministrator>(true, false, false, false, false, false, false,
+                                                                       false, false);
+      } else if (status_str == "rest") {
+        status = make_tl_object<td_api::chatMemberStatusRestricted>(true, static_cast<int32>(60 + std::time(nullptr)),
+                                                                    false, false, false, false);
+      } else if (status_str == "restkick") {
+        status = make_tl_object<td_api::chatMemberStatusRestricted>(false, static_cast<int32>(60 + std::time(nullptr)),
+                                                                    true, false, false, false);
+      } else if (status_str == "unrest") {
+        status = make_tl_object<td_api::chatMemberStatusRestricted>(true, 0, true, true, true, true);
+      }
+      if (status != nullptr) {
+        send_request(
+            make_tl_object<td_api::setChatMemberStatus>(as_chat_id(chat_id), as_user_id(user_id), std::move(status)));
+      } else {
+        LOG(ERROR) << "Unknown status \"" << status_str << "\"";
+      }
+    } else if (op == "log") {
+      string chat_id;
+      string limit;
+
+      std::tie(chat_id, limit) = split(args);
+      send_request(make_tl_object<td_api::getChatEventLog>(as_chat_id(chat_id), "", 0, to_integer<int32>(limit),
+                                                           nullptr, vector<int32>()));
+    } else if (op == "dcm") {
+      string chat_id;
+      string user_id;
+
+      std::tie(chat_id, user_id) = split(args);
+      send_request(make_tl_object<td_api::setChatMemberStatus>(as_chat_id(chat_id), as_user_id(user_id),
+                                                               make_tl_object<td_api::chatMemberStatusBanned>()));
+    } else if (op == "sn") {
+      string first_name;
+      string last_name;
+      std::tie(first_name, last_name) = split(args);
+      send_request(make_tl_object<td_api::setName>(first_name, last_name));
+    } else if (op == "sb") {
+      send_request(make_tl_object<td_api::setBio>("\n" + args + "\n" + args + "\n"));
+    } else if (op == "sun") {
+      send_request(make_tl_object<td_api::setUsername>(args));
+    } else if (op == "tbga") {
+      string group_id;
+      string everyone_is_administrator;
+
+      std::tie(group_id, everyone_is_administrator) = split(args);
+      send_request(make_tl_object<td_api::toggleBasicGroupAdministrators>(to_integer<int32>(group_id),
+                                                                          as_bool(everyone_is_administrator)));
+    } else if (op == "ccun") {
+      string chat_id;
+      string username;
+
+      std::tie(chat_id, username) = split(args);
+      send_request(make_tl_object<td_api::checkChatUsername>(as_chat_id(chat_id), username));
+    } else if (op == "ssgun" || op == "schun") {
+      string supergroup_id;
+      string username;
+
+      std::tie(supergroup_id, username) = split(args);
+      send_request(make_tl_object<td_api::setSupergroupUsername>(to_integer<int32>(supergroup_id), username));
+    } else if (op == "ssgss") {
+      string supergroup_id;
+      string sticker_set_id;
+
+      std::tie(supergroup_id, sticker_set_id) = split(args);
+      send_request(make_tl_object<td_api::setSupergroupStickerSet>(to_integer<int32>(supergroup_id),
+                                                                   to_integer<int64>(sticker_set_id)));
+    } else if (op == "tsgi") {
+      string supergroup_id;
+      string anyone_can_invite;
+
+      std::tie(supergroup_id, anyone_can_invite) = split(args);
+      send_request(make_tl_object<td_api::toggleSupergroupInvites>(to_integer<int32>(supergroup_id),
+                                                                   as_bool(anyone_can_invite)));
+    } else if (op == "tsgp") {
+      string supergroup_id;
+      string is_all_history_available;
+
+      std::tie(supergroup_id, is_all_history_available) = split(args);
+      send_request(make_tl_object<td_api::toggleSupergroupIsAllHistoryAvailable>(to_integer<int32>(supergroup_id),
+                                                                                 as_bool(is_all_history_available)));
+    } else if (op == "csgd" || op == "cchd") {
+      string supergroup_id;
+      string description;
+
+      std::tie(supergroup_id, description) = split(args);
+      send_request(make_tl_object<td_api::setSupergroupDescription>(to_integer<int32>(supergroup_id), description));
+    } else if (op == "psgm" || op == "pchm") {
+      string supergroup_id;
+      string message_id;
+
+      std::tie(supergroup_id, message_id) = split(args);
+      send_request(make_tl_object<td_api::pinSupergroupMessage>(to_integer<int32>(supergroup_id),
+                                                                as_message_id(message_id), false));
+    } else if (op == "pchms") {
+      string supergroup_id;
+      string message_id;
+
+      std::tie(supergroup_id, message_id) = split(args);
+      send_request(make_tl_object<td_api::pinSupergroupMessage>(to_integer<int32>(supergroup_id),
+                                                                as_message_id(message_id), true));
+    } else if (op == "upsgm" || op == "upchm") {
+      send_request(make_tl_object<td_api::unpinSupergroupMessage>(to_integer<int32>(args)));
+    } else if (op == "grib") {
+      send_request(make_tl_object<td_api::getRecentInlineBots>());
+    } else if (op == "spc" || op == "su" || op == "sch") {
+      send_request(make_tl_object<td_api::searchPublicChat>(args));
+    } else if (op == "spcs") {
+      send_request(make_tl_object<td_api::searchPublicChats>(args));
+    } else if (op == "sc") {
+      string limit;
+      string query;
+      std::tie(limit, query) = split(args);
+      send_request(make_tl_object<td_api::searchChats>(query, to_integer<int32>(limit)));
+    } else if (op == "scos") {
+      string limit;
+      string query;
+      std::tie(limit, query) = split(args);
+      send_request(make_tl_object<td_api::searchChatsOnServer>(query, to_integer<int32>(limit)));
+    } else if (op == "sco") {
+      string limit;
+      string query;
+      std::tie(limit, query) = split(args);
+      send_request(make_tl_object<td_api::searchContacts>(query, to_integer<int32>(limit)));
+    } else if (op == "arfc") {
+      send_request(make_tl_object<td_api::addRecentlyFoundChat>(as_chat_id(args)));
+    } else if (op == "rrfc") {
+      send_request(make_tl_object<td_api::removeRecentlyFoundChat>(as_chat_id(args)));
+    } else if (op == "crfcs") {
+      send_request(make_tl_object<td_api::clearRecentlyFoundChats>());
+    } else if (op == "gwpp") {
+      send_request(make_tl_object<td_api::getWebPagePreview>(as_caption(args)));
+    } else if (op == "gwpiv") {
+      string url;
+      string force_full;
+      std::tie(url, force_full) = split(args);
+
+      send_request(make_tl_object<td_api::getWebPageInstantView>(url, as_bool(force_full)));
+    } else if (op == "spp") {
+      send_request(make_tl_object<td_api::setProfilePhoto>(as_local_file(args)));
+    } else if (op == "sppg") {
+      string path;
+      string conversion;
+      std::tie(path, conversion) = split(args);
+      send_request(make_tl_object<td_api::setProfilePhoto>(as_generated_file(path, conversion)));
+    } else if (op == "sh") {
+      auto prefix = std::move(args);
+      send_request(make_tl_object<td_api::searchHashtags>(prefix, 10));
+    } else if (op == "rrh") {
+      auto hashtag = std::move(args);
+      send_request(make_tl_object<td_api::removeRecentHashtag>(hashtag));
+    } else if (op == "view") {
+      string chat_id;
+      string message_ids;
+      std::tie(chat_id, message_ids) = split(args);
+
+      send_request(make_tl_object<td_api::viewMessages>(as_chat_id(chat_id), as_message_ids(message_ids), true));
+    } else if (op == "omc") {
+      string chat_id;
+      string message_id;
+      std::tie(chat_id, message_id) = split(args);
+
+      send_request(make_tl_object<td_api::openMessageContent>(as_chat_id(chat_id), as_message_id(message_id)));
+    } else if (op == "racm") {
+      string chat_id = args;
+      send_request(make_tl_object<td_api::readAllChatMentions>(as_chat_id(chat_id)));
+    } else if (op == "dpp") {
+      send_request(make_tl_object<td_api::deleteProfilePhoto>(to_integer<int64>(args)));
+    } else if (op == "gns") {
+      send_request(make_tl_object<td_api::getNotificationSettings>(get_notification_settings_scope(args)));
+    } else if (op == "sns") {
+      string scope;
+      string settings;
+
+      std::tie(scope, settings) = split(args);
+
+      string mute_for;
+      string sound;
+      string show_previews;
+
+      std::tie(mute_for, settings) = split(settings, ',');
+      std::tie(sound, show_previews) = split(settings, ',');
+
+      send_request(make_tl_object<td_api::setNotificationSettings>(
+          get_notification_settings_scope(scope),
+          make_tl_object<td_api::notificationSettings>(to_integer<int32>(mute_for), sound, as_bool(show_previews))));
+    } else if (op == "rans") {
+      send_request(make_tl_object<td_api::resetAllNotificationSettings>());
+    } else if (op == "gcrss") {
+      send_request(make_tl_object<td_api::getChatReportSpamState>(as_chat_id(args)));
+    } else if (op == "ccrss") {
+      string chat_id;
+      string is_spam_chat;
+      std::tie(chat_id, is_spam_chat) = split(args);
+
+      send_request(make_tl_object<td_api::changeChatReportSpamState>(as_chat_id(chat_id), as_bool(is_spam_chat)));
+    } else if (op == "rc") {
+      string chat_id;
+      string reason_str;
+      string message_ids;
+      std::tie(chat_id, args) = split(args);
+      std::tie(reason_str, message_ids) = split(args);
+
+      tl_object_ptr<td_api::ChatReportReason> reason;
+      if (reason_str == "spam") {
+        reason = make_tl_object<td_api::chatReportReasonSpam>();
+      } else if (reason_str == "violence") {
+        reason = make_tl_object<td_api::chatReportReasonViolence>();
+      } else if (reason_str == "porno") {
+        reason = make_tl_object<td_api::chatReportReasonPornography>();
+      } else {
+        reason = make_tl_object<td_api::chatReportReasonCustom>(reason_str);
+      }
+
+      send_request(
+          make_tl_object<td_api::reportChat>(as_chat_id(chat_id), std::move(reason), as_message_ids(message_ids)));
+    } else if (op == "rsgs" || op == "rchs") {
+      string supergroup_id;
+      string user_id;
+      string message_ids;
+      std::tie(supergroup_id, args) = split(args);
+      std::tie(user_id, message_ids) = split(args);
+
+      send_request(make_tl_object<td_api::reportSupergroupSpam>(to_integer<int32>(supergroup_id), as_user_id(user_id),
+                                                                as_message_ids(message_ids)));
+    } else if (op == "gdiff") {
+      send_request(make_tl_object<td_api::testGetDifference>());
+    } else if (op == "cproxy") {
+      send_request(make_tl_object<td_api::setProxy>(make_tl_object<td_api::proxyEmpty>()));
+    } else if (op == "sproxy") {
+      string server;
+      string port;
+      string user;
+      string password;
+      std::tie(server, args) = split(args);
+      std::tie(port, args) = split(args);
+      std::tie(user, password) = split(args);
+
+      send_request(make_tl_object<td_api::setProxy>(
+          make_tl_object<td_api::proxySocks5>(server, to_integer<int32>(port), user, password)));
+    } else if (op == "gproxy") {
+      send_request(make_tl_object<td_api::getProxy>());
+    } else if (op == "SetVerbosity") {
+      td::Log::set_verbosity_level(to_integer<int>(args));
+    } else if (op == "q" || op == "Quit") {
+      quit();
+    } else if (op == "dnq" || op == "DumpNetQueries") {
+      dump_pending_network_queries();
+    } else if (op == "fatal") {
+      LOG(FATAL) << "Fatal!";
+    } else if (op == "unreachable") {
+      UNREACHABLE();
+    } else {
+      op_not_found_count++;
+    }
+
+    if (op_not_found_count == OP_BLOCK_COUNT && !cmd.empty()) {
+      LOG(ERROR) << "Unknown command \"" << cmd << "\" of length " << cmd.size();
+    }
+  }
+
+  bool inited_ = false;
+  void loop() override {
+    if (!inited_) {
+      inited_ = true;
+      init();
+    }
+#if !TD_WINDOWS
+#ifdef USE_READLINE
+    if (can_read(stdin_)) {
+      rl_callback_read_char();
+      stdin_.get_fd().clear_flags(Fd::Read);
+    }
+#else
+    auto r = stdin_.flush_read();
+    CHECK(r.is_ok());
+    while (true) {
+      auto cmd = process_stdin(&stdin_.input_buffer());
+      if (cmd.is_error()) {
+        break;
+      }
+      add_cmd(cmd.ok().as_slice().str());
+    }
+#endif
+
+    while (!cmd_queue_.empty() && !close_flag_) {
+      auto cmd = std::move(cmd_queue_.front());
+      cmd_queue_.pop();
+      on_cmd(std::move(cmd));
+    }
+#endif
+
+    if (ready_to_stop_ && close_flag_ && is_stdin_reader_stopped_) {
+#ifdef USE_READLINE
+      rl_callback_handler_remove();
+#endif
+      Scheduler::instance()->finish();
+      LOG(WARNING) << "STOP";
+      stop();
+    }
+  }
+
+  void timeout_expired() override {
+    if (close_flag_) {
+      return;
+    }
+
+    for (auto it = pending_file_generations.begin(); it != pending_file_generations.end();) {
+      auto left_size = it->size - it->local_size;
+      CHECK(left_size > 0);
+      if (it->part_size > left_size) {
+        it->part_size = left_size;
+      }
+      BufferSlice block(it->part_size);
+      FileFd::open(it->source, FileFd::Flags::Read).move_as_ok().pread(block.as_slice(), it->local_size).ensure();
+      auto open_flags = FileFd::Flags::Write | (it->local_size ? 1 : FileFd::Flags::Truncate | FileFd::Flags::Create);
+      FileFd::open(it->destination, open_flags).move_as_ok().pwrite(block.as_slice(), it->local_size).ensure();
+      it->local_size += it->part_size;
+      if (it->local_size == it->size) {
+        send_request(make_tl_object<td_api::setFileGenerationProgress>(it->id, it->size, it->size));
+        send_request(make_tl_object<td_api::finishFileGeneration>(it->id, nullptr));
+        it = pending_file_generations.erase(it);
+      } else {
+        send_request(
+            make_tl_object<td_api::setFileGenerationProgress>(it->id, (it->size + it->local_size) / 2, it->local_size));
+        ++it;
+      }
+    }
+
+    if (!pending_file_generations.empty()) {
+      set_timeout_in(0.01);
+    }
+  }
+
+  void hangup_shared() override {
+    CHECK(get_link_token() == 1);
+    LOG(INFO) << "StdinReader stopped";
+    is_stdin_reader_stopped_ = true;
+    yield();
+  }
+
+  void add_cmd(string cmd) {
+    cmd_queue_.push(std::move(cmd));
+  }
+
+  int32 my_id_ = 0;
+
+  bool use_test_dc_ = false;
+  ActorOwn<ClientActor> td_;
+  std::queue<string> cmd_queue_;
+  bool close_flag_ = false;
+  bool ready_to_stop_ = false;
+  bool is_stdin_reader_stopped_ = false;
+
+  bool get_chat_list_ = false;
+  bool disable_network_ = false;
+  int api_id_ = 0;
+  std::string api_hash_;
+
+#if TD_WINDOWS
+  ActorOwn<> stdin_reader_;
+#endif
+};
+CliClient *CliClient::instance_ = nullptr;
+
+void quit() {
+  CliClient::quit_instance();
+}
+
+static void fail_signal(int sig) {
+  signal_safe_write_signal_number(sig);
+  while (true) {
+    // spin forever to allow debugger to attach
+  }
+}
+
+static void usage() {
+  //TODO:
+}
+
+static void on_fatal_error(const char *error) {
+  std::cerr << "Fatal error: " << error << std::endl;
+}
+
+void main(int argc, char **argv) {
+  ignore_signal(SignalType::HangUp).ensure();
+  ignore_signal(SignalType::Pipe).ensure();
+  set_signal_handler(SignalType::Error, fail_signal).ensure();
+  set_signal_handler(SignalType::Abort, fail_signal).ensure();
+  td::Log::set_fatal_error_callback(on_fatal_error);
+
+  const char *locale_name = (std::setlocale(LC_ALL, "fr-FR") == nullptr ? "" : "fr-FR");
+  std::locale new_locale(locale_name);
+  std::locale::global(new_locale);
+  SCOPE_EXIT {
+    std::locale::global(std::locale::classic());
+  };
+
+  CliLog cli_log;
+  log_interface = &cli_log;
+
+  td::FileLog file_log;
+  td::TsLog ts_log(&file_log);
+
+  int new_verbosity_level = VERBOSITY_NAME(INFO);
+  bool use_test_dc = false;
+  bool get_chat_list = false;
+  bool disable_network = false;
+  auto api_id = [](auto x) -> int32 {
+    if (x) {
+      return td::to_integer<int32>(Slice(x));
+    }
+    return 0;
+  }(std::getenv("TD_API_ID"));
+  auto api_hash = [](auto x) -> std::string {
+    if (x) {
+      return x;
+    }
+    return "";
+  }(std::getenv("TD_API_HASH"));
+  // TODO port OptionsParser to Windows
+  for (int i = 1; i < argc; i++) {
+    if (!std::strcmp(argv[i], "--test")) {
+      use_test_dc = true;
+    } else if (!std::strncmp(argv[i], "-v", 2)) {
+      const char *arg = argv[i] + 2;
+      if (*arg == '\0' && i + 1 < argc) {
+        arg = argv[++i];
+      }
+      int new_verbosity = 0;
+      if (arg[0] == 'v') {
+        new_verbosity = 1;
+        while (arg[0] == 'v') {
+          new_verbosity++;
+          arg++;
+        }
+      }
+      new_verbosity += to_integer<int>(Slice(arg));
+      new_verbosity_level = VERBOSITY_NAME(FATAL) + new_verbosity;
+    } else if (!std::strncmp(argv[i], "-l", 2)) {
+      const char *arg = argv[i] + 2;
+      if (*arg == '\0' && i + 1 < argc) {
+        arg = argv[++i];
+      }
+      if (file_log.init(arg) && file_log.init(arg) && file_log.init(arg, 1000 << 20)) {
+        log_interface = &ts_log;
+      }
+    } else if (!std::strcmp(argv[i], "-W")) {
+      get_chat_list = true;
+    } else if (!std::strcmp(argv[i], "--disable-network") || !std::strcmp(argv[i], "-n")) {
+      disable_network = true;
+    } else if (!std::strcmp(argv[i], "--api_id")) {
+      if (i + 1 >= argc) {
+        return usage();
+      }
+      api_id = td::to_integer<int32>(Slice(argv[++i]));
+    } else if (!std::strcmp(argv[i], "--api_hash")) {
+      if (i + 1 >= argc) {
+        return usage();
+      }
+      api_hash = argv[++i];
+    }
+  }
+
+  if (api_id == 0 || api_hash == "") {
+    LOG(ERROR) << "You should provide some valid api_id and api_hash";
+    return usage();
+  }
+
+  SET_VERBOSITY_LEVEL(new_verbosity_level);
+
+  {
+    ConcurrentScheduler scheduler;
+    scheduler.init(4);
+
+    scheduler
+        .create_actor_unsafe<CliClient>(0, "CliClient", use_test_dc, get_chat_list, disable_network, api_id, api_hash)
+        .release();
+
+    scheduler.start();
+    while (scheduler.run_main(100)) {
+    }
+    scheduler.finish();
+  }
+
+  dump_memory_usage();
+}
+}  // namespace td
+
+int main(int argc, char **argv) {
+  td::main(argc, argv);
+}
diff --git a/libs/tdlib/td/td/telegram/files/FileDb.cpp b/libs/tdlib/td/td/telegram/files/FileDb.cpp
new file mode 100644
index 0000000000..96795dcea1
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileDb.cpp
@@ -0,0 +1,290 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/files/FileDb.h"
+
+#include "td/telegram/files/FileLocation.h"
+#include "td/telegram/Version.h"
+
+#include "td/actor/actor.h"
+
+#include "td/db/SqliteKeyValueSafe.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Slice.h"
+#include "td/utils/StackAllocator.h"
+#include "td/utils/Status.h"
+#include "td/utils/tl_helpers.h"
+#include "td/utils/tl_parsers.h"
+#include "td/utils/tl_storers.h"
+
+namespace td {
+
+Status drop_file_db(SqliteDb &db, int32 version) {
+  LOG(WARNING) << "Drop file_db " << tag("version", version) << tag("current_db_version", current_db_version());
+  TRY_STATUS(SqliteKeyValue::drop(db, "files"));
+  return Status::OK();
+}
+
+Status fix_file_remote_location_key_bug(SqliteDb &db);
+Status init_file_db(SqliteDb &db, int32 version) {
+  LOG(INFO) << "Init file db " << tag("version", version);
+
+  // Check if database exists
+  TRY_RESULT(has_table, db.has_table("files"));
+
+  if (!has_table) {
+    version = 0;
+  } else if (version < static_cast<int32>(DbVersion::DialogDbCreated)) {
+    TRY_STATUS(drop_file_db(db, version));
+    version = 0;
+  } else if (version < static_cast<int>(DbVersion::FixFileRemoteLocationKeyBug)) {
+    TRY_STATUS(fix_file_remote_location_key_bug(db));
+  }
+
+  if (version == 0) {
+    TRY_STATUS(SqliteKeyValue::init(db, "files"));
+  }
+  return Status::OK();
+}
+
+class FileDb : public FileDbInterface {
+ public:
+  class FileDbActor : public Actor {
+   public:
+    using Id = FileDbInterface::Id;
+    FileDbActor(Id current_pmc_id, std::shared_ptr<SqliteKeyValueSafe> file_kv_safe)
+        : current_pmc_id_(current_pmc_id), file_kv_safe_(std::move(file_kv_safe)) {
+    }
+
+    void close(Promise<> promise) {
+      file_kv_safe_.reset();
+      LOG(INFO) << "FileDb is closed";
+      promise.set_value(Unit());
+      stop();
+    }
+
+    void load_file_data(const string &key, Promise<FileData> promise) {
+      promise.set_result(load_file_data_impl(file_pmc(), key));
+    }
+
+    void clear_file_data(Id id, const string &remote_key, const string &local_key, const string &generate_key) {
+      auto &pmc = file_pmc();
+      pmc.begin_transaction().ensure();
+      SCOPE_EXIT {
+        pmc.commit_transaction().ensure();
+      };
+
+      if (id > current_pmc_id_) {
+        pmc.set("file_id", to_string(id));
+        current_pmc_id_ = id;
+      }
+
+      pmc.erase("file" + to_string(id));
+      LOG(DEBUG) << "ERASE " << format::as_hex_dump<4>(Slice(PSLICE() << "file" << to_string(id)));
+
+      if (!remote_key.empty()) {
+        pmc.erase(remote_key);
+        LOG(DEBUG) << "ERASE remote " << format::as_hex_dump<4>(Slice(remote_key));
+      }
+      if (!local_key.empty()) {
+        pmc.erase(local_key);
+        LOG(DEBUG) << "ERASE local " << format::as_hex_dump<4>(Slice(local_key));
+      }
+      if (!generate_key.empty()) {
+        pmc.erase(generate_key);
+      }
+    }
+    void store_file_data(Id id, const string &file_data, const string &remote_key, const string &local_key,
+                         const string &generate_key) {
+      auto &pmc = file_pmc();
+      pmc.begin_transaction().ensure();
+      SCOPE_EXIT {
+        pmc.commit_transaction().ensure();
+      };
+
+      if (id > current_pmc_id_) {
+        pmc.set("file_id", to_string(id));
+        current_pmc_id_ = id;
+      }
+
+      pmc.set("file" + to_string(id), file_data);
+
+      if (!remote_key.empty()) {
+        pmc.set(remote_key, to_string(id));
+      }
+      if (!local_key.empty()) {
+        pmc.set(local_key, to_string(id));
+      }
+      if (!generate_key.empty()) {
+        pmc.set(generate_key, to_string(id));
+      }
+    }
+    void store_file_data_ref(Id id, Id new_id) {
+      auto &pmc = file_pmc();
+      pmc.begin_transaction().ensure();
+      SCOPE_EXIT {
+        pmc.commit_transaction().ensure();
+      };
+
+      if (id > current_pmc_id_) {
+        pmc.set("file_id", to_string(id));
+        current_pmc_id_ = id;
+      }
+
+      pmc.set("file" + to_string(id), "@@" + to_string(new_id));
+    }
+
+   private:
+    Id current_pmc_id_;
+    std::shared_ptr<SqliteKeyValueSafe> file_kv_safe_;
+
+    SqliteKeyValue &file_pmc() {
+      return file_kv_safe_->get();
+    }
+  };
+
+  explicit FileDb(std::shared_ptr<SqliteKeyValueSafe> kv_safe, int scheduler_id = -1) {
+    file_kv_safe_ = std::move(kv_safe);
+    CHECK(file_kv_safe_);
+    current_pmc_id_ = to_integer<int32>(file_kv_safe_->get().get("file_id"));
+    file_db_actor_ =
+        create_actor_on_scheduler<FileDbActor>("FileDbActor", scheduler_id, current_pmc_id_, file_kv_safe_);
+  }
+
+  Id create_pmc_id() override {
+    return ++current_pmc_id_;
+  }
+
+  void close(Promise<> promise) override {
+    send_closure(std::move(file_db_actor_), &FileDbActor::close, std::move(promise));
+  }
+
+  void get_file_data_impl(string key, Promise<FileData> promise) override {
+    send_closure(file_db_actor_, &FileDbActor::load_file_data, std::move(key), std::move(promise));
+  }
+
+  Result<FileData> get_file_data_sync_impl(string key) override {
+    return load_file_data_impl(file_kv_safe_->get(), key);
+  }
+
+  void clear_file_data(Id id, const FileData &file_data) override {
+    string remote_key;
+    if (file_data.remote_.type() == RemoteFileLocation::Type::Full) {
+      remote_key = as_key(file_data.remote_.full());
+    }
+    string local_key;
+    if (file_data.local_.type() == LocalFileLocation::Type::Full) {
+      local_key = as_key(file_data.local_.full());
+    }
+    string generate_key;
+    if (file_data.generate_ != nullptr) {
+      generate_key = as_key(*file_data.generate_);
+    }
+    send_closure(file_db_actor_, &FileDbActor::clear_file_data, id, remote_key, local_key, generate_key);
+  }
+  void set_file_data(Id id, const FileData &file_data, bool new_remote, bool new_local, bool new_generate) override {
+    string remote_key;
+    if (file_data.remote_.type() == RemoteFileLocation::Type::Full && new_remote) {
+      remote_key = as_key(file_data.remote_.full());
+    }
+    string local_key;
+    if (file_data.local_.type() == LocalFileLocation::Type::Full && new_local) {
+      local_key = as_key(file_data.local_.full());
+    }
+    string generate_key;
+    if (file_data.generate_ != nullptr && new_generate) {
+      generate_key = as_key(*file_data.generate_);
+    }
+    LOG(DEBUG) << "SAVE " << id << " -> " << file_data << " "
+               << tag("remote", format::as_hex_dump<4>(Slice(remote_key)))
+               << tag("local", format::as_hex_dump<4>(Slice(local_key)));
+    send_closure(file_db_actor_, &FileDbActor::store_file_data, id, serialize(file_data), remote_key, local_key,
+                 generate_key);
+  }
+
+  void set_file_data_ref(Id id, Id new_id) override {
+    send_closure(file_db_actor_, &FileDbActor::store_file_data_ref, id, new_id);
+  }
+  SqliteKeyValue &pmc() override {
+    return file_kv_safe_->get();
+  }
+
+ private:
+  ActorOwn<FileDbActor> file_db_actor_;
+  Id current_pmc_id_;
+  std::shared_ptr<SqliteKeyValueSafe> file_kv_safe_;
+
+  static Result<FileData> load_file_data_impl(SqliteKeyValue &pmc, const string &key) {
+    //LOG(DEBUG) << "Load by key " << format::as_hex_dump<4>(Slice(key));
+    TRY_RESULT(id, get_id(pmc, key));
+
+    string data_str;
+    int attempt_count = 0;
+    while (true) {
+      if (attempt_count > 5) {
+        LOG(FATAL) << "cycle in files db?";
+      }
+      attempt_count++;
+
+      data_str = pmc.get(PSTRING() << "file" << id);
+      auto data_slice = Slice(data_str);
+
+      if (data_slice.substr(0, 2) == "@@") {
+        id = to_integer<Id>(data_slice.substr(2));
+      } else {
+        break;
+      }
+    }
+    //LOG(DEBUG) << "By id " << id << " found data " << format::as_hex_dump<4>(Slice(data_str));
+
+    FileData data;
+    auto status = unserialize(data, data_str);
+    if (status.is_error()) {
+      return std::move(status);
+    }
+    return std::move(data);
+  }
+
+  static Result<Id> get_id(SqliteKeyValue &pmc, const string &key) TD_WARN_UNUSED_RESULT {
+    auto id_str = pmc.get(key);
+    //LOG(DEBUG) << "Found id " << id_str << " by key " << format::as_hex_dump<4>(Slice(key));
+    if (id_str.empty()) {
+      return Status::Error("There is no such a key in db");
+    }
+    return to_integer<Id>(id_str);
+  }
+};
+
+std::shared_ptr<FileDbInterface> create_file_db(std::shared_ptr<SqliteConnectionSafe> connection, int scheduler_id) {
+  auto kv = std::make_shared<SqliteKeyValueSafe>("files", std::move(connection));
+  return std::make_shared<FileDb>(std::move(kv), scheduler_id);
+}
+
+Status fix_file_remote_location_key_bug(SqliteDb &db) {
+  static const int32 OLD_KEY_MAGIC = 0x64378433;
+  SqliteKeyValue kv;
+  kv.init_with_connection(db.clone(), "files").ensure();
+  auto ptr = StackAllocator::alloc(4);
+  MutableSlice prefix = ptr.as_slice();
+  TlStorerUnsafe(prefix.begin()).store_int(OLD_KEY_MAGIC);
+  kv.get_by_prefix(prefix, [&](Slice key, Slice value) {
+    CHECK(TlParser(key).fetch_int() == OLD_KEY_MAGIC);
+    auto remote_str = PSTRING() << key.substr(4, 4) << Slice("\0\0\0\0") << key.substr(8);
+    FullRemoteFileLocation remote;
+    if (unserialize(remote, remote_str).is_ok()) {
+      kv.set(as_key(remote), value);
+    }
+    LOG(DEBUG) << "ERASE " << format::as_hex_dump<4>(Slice(key));
+    kv.erase(key);
+  });
+  return Status::OK();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileDb.h b/libs/tdlib/td/td/telegram/files/FileDb.h
new file mode 100644
index 0000000000..d53fb32091
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileDb.h
@@ -0,0 +1,75 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/files/FileLocation.h"
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/Status.h"
+
+#include <memory>
+
+namespace td {
+class SqliteDb;
+class SqliteConnectionSafe;
+class SqliteKeyValue;
+}  // namespace td
+
+namespace td {
+Status drop_file_db(SqliteDb &db, int32 version) TD_WARN_UNUSED_RESULT;
+Status init_file_db(SqliteDb &db, int32 version) TD_WARN_UNUSED_RESULT;
+
+class FileDbInterface;
+std::shared_ptr<FileDbInterface> create_file_db(std::shared_ptr<SqliteConnectionSafe> connection,
+                                                int32 scheduler_id = -1) TD_WARN_UNUSED_RESULT;
+
+using FileDbId = uint64;
+
+class FileDbInterface {
+ public:
+  using Id = FileDbId;
+  FileDbInterface() = default;
+  FileDbInterface(const FileDbInterface &) = delete;
+  FileDbInterface &operator=(const FileDbInterface &) = delete;
+  virtual ~FileDbInterface() = default;
+
+  // non thread safe
+  virtual Id create_pmc_id() = 0;
+
+  // thread safe
+  virtual void close(Promise<> promise) = 0;
+  template <class LocationT>
+  void get_file_data(const LocationT &location, Promise<FileData> promise) {
+    get_file_data(as_key(location), std::move(promise));
+  }
+
+  template <class LocationT>
+  Result<FileData> get_file_data_sync(const LocationT &location) {
+    auto res = get_file_data_sync_impl(as_key(location));
+    if (res.is_ok()) {
+      LOG(DEBUG) << "GET " << location << " " << res.ok();
+    } else {
+      LOG(DEBUG) << "GET " << location << " " << res.error();
+    }
+    return res;
+  }
+
+  virtual void clear_file_data(Id id, const FileData &file_data) = 0;
+  virtual void set_file_data(Id id, const FileData &file_data, bool new_remote, bool new_local, bool new_generate) = 0;
+  virtual void set_file_data_ref(Id id, Id new_id) = 0;
+
+  // For FileStatsWorker. TODO: remove it
+  virtual SqliteKeyValue &pmc() = 0;
+
+ private:
+  virtual void get_file_data_impl(string key, Promise<FileData> promise) = 0;
+  virtual Result<FileData> get_file_data_sync_impl(string key) = 0;
+};
+;
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileDownloader.cpp b/libs/tdlib/td/td/telegram/files/FileDownloader.cpp
new file mode 100644
index 0000000000..29180dd701
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileDownloader.cpp
@@ -0,0 +1,461 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/files/FileDownloader.h"
+
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/files/FileLoaderUtils.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/UniqueId.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/crypto.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Slice.h"
+
+#include <tuple>
+
+namespace td {
+
+FileDownloader::FileDownloader(const FullRemoteFileLocation &remote, const LocalFileLocation &local, int64 size,
+                               string name, const FileEncryptionKey &encryption_key, bool is_small, bool search_file,
+                               std::unique_ptr<Callback> callback)
+    : remote_(remote)
+    , local_(local)
+    , size_(size)
+    , name_(std::move(name))
+    , encryption_key_(encryption_key)
+    , callback_(std::move(callback))
+    , is_small_(is_small)
+    , search_file_(search_file) {
+  if (!encryption_key.empty()) {
+    set_ordered_flag(true);
+  }
+}
+
+Result<FileLoader::FileInfo> FileDownloader::init() {
+  SCOPE_EXIT {
+    try_release_fd();
+  };
+  if (local_.type() == LocalFileLocation::Type::Full) {
+    return Status::Error("File is already downloaded");
+  }
+  int ready_part_count = 0;
+  int32 part_size = 0;
+  if (local_.type() == LocalFileLocation::Type::Partial) {
+    const auto &partial = local_.partial();
+    path_ = partial.path_;
+    auto result_fd = FileFd::open(path_, FileFd::Write | FileFd::Read);
+    // TODO: check timestamps..
+    if (result_fd.is_ok()) {
+      if (!encryption_key_.empty()) {
+        CHECK(partial.iv_.size() == 32) << partial.iv_.size();
+        encryption_key_.mutable_iv() = as<UInt256>(partial.iv_.data());
+        next_part_ = partial.ready_part_count_;
+      }
+      fd_ = result_fd.move_as_ok();
+      part_size = partial.part_size_;
+      ready_part_count = partial.ready_part_count_;
+    }
+  }
+  if (search_file_ && fd_.empty() && size_ > 0 && size_ < 1000 * (1 << 20) && encryption_key_.empty() &&
+      !remote_.is_web()) {
+    [&] {
+      TRY_RESULT(path, search_file(get_files_dir(remote_.file_type_), name_, size_));
+      TRY_RESULT(fd, FileFd::open(path, FileFd::Read));
+      LOG(INFO) << "Check hash of local file " << path;
+      path_ = std::move(path);
+      fd_ = std::move(fd);
+      need_check_ = true;
+      only_check_ = true;
+      part_size = 32 * (1 << 10);
+      ready_part_count = narrow_cast<int>((size_ + part_size - 1) / part_size);
+      return Status::OK();
+    }();
+  }
+
+  std::vector<int> parts(ready_part_count);
+  for (int i = 0; i < ready_part_count; i++) {
+    parts[i] = i;
+  }
+
+  FileInfo res;
+  res.size = size_;
+  res.is_size_final = true;
+  res.part_size = part_size;
+  res.ready_parts = std::move(parts);
+  res.use_part_count_limit = false;
+  res.only_check = only_check_;
+  res.need_delay = !is_small_ && (remote_.file_type_ == FileType::VideoNote ||
+                                  remote_.file_type_ == FileType::VoiceNote || remote_.file_type_ == FileType::Audio ||
+                                  remote_.file_type_ == FileType::Video || remote_.file_type_ == FileType::Animation ||
+                                  (remote_.file_type_ == FileType::Encrypted && size_ > (1 << 20)));
+  return res;
+}
+Status FileDownloader::on_ok(int64 size) {
+  auto dir = get_files_dir(remote_.file_type_);
+
+  std::string path;
+  if (only_check_) {
+    path = path_;
+  } else {
+    TRY_RESULT(perm_path, create_from_temp(path_, dir, name_));
+    path = std::move(perm_path);
+  }
+  fd_.close();
+  callback_->on_ok(FullLocalFileLocation(remote_.file_type_, std::move(path), 0), size);
+  return Status::OK();
+}
+void FileDownloader::on_error(Status status) {
+  fd_.close();
+  callback_->on_error(std::move(status));
+}
+
+Result<bool> FileDownloader::should_restart_part(Part part, NetQueryPtr &net_query) {
+  // Check if we should use CDN or reupload file to CDN
+
+  if (net_query->is_error()) {
+    if (net_query->error().message() == "FILE_TOKEN_INVALID") {
+      use_cdn_ = false;
+      return true;
+    }
+    if (net_query->error().message() == "REQUEST_TOKEN_INVALID") {
+      return true;
+    }
+    return false;
+  }
+
+  switch (narrow_cast<QueryType>(UniqueId::extract_key(net_query->id()))) {
+    case QueryType::Default: {
+      if (net_query->ok_tl_constructor() == telegram_api::upload_fileCdnRedirect::ID) {
+        LOG(DEBUG) << part.id << " got REDIRECT";
+        TRY_RESULT(file_base, fetch_result<telegram_api::upload_getFile>(net_query->ok()));
+        CHECK(file_base->get_id() == telegram_api::upload_fileCdnRedirect::ID);
+        auto file = move_tl_object_as<telegram_api::upload_fileCdnRedirect>(file_base);
+
+        auto new_cdn_file_token = file->file_token_.as_slice();
+        if (cdn_file_token_ == new_cdn_file_token) {
+          return true;
+        }
+
+        use_cdn_ = true;
+        need_check_ = true;
+        cdn_file_token_generation_++;
+        cdn_file_token_ = new_cdn_file_token.str();
+        cdn_dc_id_ = DcId::external(file->dc_id_);
+        cdn_encryption_key_ = file->encryption_key_.as_slice().str();
+        cdn_encryption_iv_ = file->encryption_iv_.as_slice().str();
+        add_hash_info(file->file_hashes_);
+        if (cdn_encryption_iv_.size() != 16 || cdn_encryption_key_.size() != 32) {
+          return Status::Error("Wrong ctr key or iv size");
+        }
+
+        return true;
+      }
+      return false;
+    }
+    case QueryType::ReuploadCDN: {
+      TRY_RESULT(file_hashes, fetch_result<telegram_api::upload_reuploadCdnFile>(net_query->ok()));
+      add_hash_info(file_hashes);
+      LOG(DEBUG) << part.id << " got REUPLOAD_OK";
+      return true;
+    }
+    case QueryType::CDN: {
+      if (net_query->ok_tl_constructor() == telegram_api::upload_cdnFileReuploadNeeded::ID) {
+        LOG(DEBUG) << part.id << " got REUPLOAD";
+        TRY_RESULT(file_base, fetch_result<telegram_api::upload_getCdnFile>(net_query->ok()));
+        CHECK(file_base->get_id() == telegram_api::upload_cdnFileReuploadNeeded::ID);
+        auto file = move_tl_object_as<telegram_api::upload_cdnFileReuploadNeeded>(file_base);
+        cdn_part_reupload_token_[part.id] = file->request_token_.as_slice().str();
+        return true;
+      }
+      auto it = cdn_part_file_token_generation_.find(part.id);
+      CHECK(it != cdn_part_file_token_generation_.end());
+      if (it->second != cdn_file_token_generation_) {
+        LOG(DEBUG) << part.id << " got part with old file_token";
+        return true;
+      }
+      return false;
+    }
+    default:
+      UNREACHABLE();
+  }
+
+  return false;
+}
+Result<std::pair<NetQueryPtr, bool>> FileDownloader::start_part(Part part, int32 part_count) {
+  if (!encryption_key_.empty()) {
+    part.size = (part.size + 15) & ~15;  // fix for last part
+  }
+  // auto size = part.size;
+  //// sometimes we can ask more than server has, just to check size
+  // if (size < get_part_size()) {
+  // size = min(size + 16, get_part_size());
+  // LOG(INFO) << "Ask " << size << " instead of " << part.size;
+  //}
+  auto size = get_part_size();
+  CHECK(part.size <= size);
+
+  callback_->on_start_download();
+
+  NetQueryPtr net_query;
+  if (!use_cdn_) {
+    net_query = G()->net_query_creator().create(
+        UniqueId::next(UniqueId::Type::Default, static_cast<uint8>(QueryType::Default)),
+        remote_.is_web()
+            ? create_storer(telegram_api::upload_getWebFile(remote_.as_input_web_file_location(),
+                                                            static_cast<int32>(part.offset), static_cast<int32>(size)))
+            : create_storer(telegram_api::upload_getFile(remote_.as_input_file_location(),
+                                                         static_cast<int32>(part.offset), static_cast<int32>(size))),
+        remote_.get_dc_id(), is_small_ ? NetQuery::Type::DownloadSmall : NetQuery::Type::Download);
+  } else {
+    if (remote_.is_web()) {
+      return Status::Error("Can't download web file from CDN");
+    }
+    auto it = cdn_part_reupload_token_.find(part.id);
+    if (it == cdn_part_reupload_token_.end()) {
+      auto query = telegram_api::upload_getCdnFile(BufferSlice(cdn_file_token_), static_cast<int32>(part.offset),
+                                                   static_cast<int32>(size));
+      cdn_part_file_token_generation_[part.id] = cdn_file_token_generation_;
+      LOG(DEBUG) << part.id << " " << to_string(query);
+      net_query = G()->net_query_creator().create(
+          UniqueId::next(UniqueId::Type::Default, static_cast<uint8>(QueryType::CDN)), create_storer(query), cdn_dc_id_,
+          is_small_ ? NetQuery::Type::DownloadSmall : NetQuery::Type::Download, NetQuery::AuthFlag::Off);
+    } else {
+      auto query = telegram_api::upload_reuploadCdnFile(BufferSlice(cdn_file_token_), BufferSlice(it->second));
+      LOG(DEBUG) << part.id << " " << to_string(query);
+      net_query = G()->net_query_creator().create(
+          UniqueId::next(UniqueId::Type::Default, static_cast<uint8>(QueryType::ReuploadCDN)), create_storer(query),
+          remote_.get_dc_id(), is_small_ ? NetQuery::Type::DownloadSmall : NetQuery::Type::Download,
+          NetQuery::AuthFlag::On);
+      cdn_part_reupload_token_.erase(it);
+    }
+  }
+  net_query->file_type_ = narrow_cast<int32>(remote_.file_type_);
+  return std::make_pair(std::move(net_query), false);
+}
+
+Result<size_t> FileDownloader::process_part(Part part, NetQueryPtr net_query) {
+  if (net_query->is_error()) {
+    return std::move(net_query->error());
+  }
+
+  BufferSlice bytes;
+  bool need_cdn_decrypt = false;
+  auto query_type = narrow_cast<QueryType>(UniqueId::extract_key(net_query->id()));
+  switch (query_type) {
+    case QueryType::Default: {
+      if (remote_.is_web()) {
+        TRY_RESULT(file, fetch_result<telegram_api::upload_getWebFile>(net_query->ok()));
+        bytes = std::move(file->bytes_);
+      } else {
+        TRY_RESULT(file_base, fetch_result<telegram_api::upload_getFile>(net_query->ok()));
+        CHECK(file_base->get_id() == telegram_api::upload_file::ID);
+        auto file = move_tl_object_as<telegram_api::upload_file>(file_base);
+        LOG(DEBUG) << part.id << " upload_getFile result";
+        bytes = std::move(file->bytes_);
+      }
+      break;
+    }
+    case QueryType::CDN: {
+      TRY_RESULT(file_base, fetch_result<telegram_api::upload_getCdnFile>(net_query->ok()));
+      CHECK(file_base->get_id() == telegram_api::upload_cdnFile::ID);
+      auto file = move_tl_object_as<telegram_api::upload_cdnFile>(file_base);
+      LOG(DEBUG) << part.id << " upload_getCdnFile result";
+      bytes = std::move(file->bytes_);
+      need_cdn_decrypt = true;
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+
+  auto padded_size = part.size;
+  if (!encryption_key_.empty()) {
+    padded_size = (part.size + 15) & ~15;
+  }
+  LOG(INFO) << "Got " << bytes.size() << " padded_size=" << padded_size;
+  if (bytes.size() > padded_size) {
+    return Status::Error("Part size is more than requested");
+  }
+  if (bytes.empty()) {
+    return 0;
+  }
+
+  // Encryption
+  if (need_cdn_decrypt) {
+    auto iv = as<UInt128>(cdn_encryption_iv_.c_str());
+    CHECK(part.offset % 16 == 0);
+    auto offset = narrow_cast<uint32>(part.offset / 16);
+    offset =
+        ((offset & 0xff) << 24) | ((offset & 0xff00) << 8) | ((offset & 0xff0000) >> 8) | ((offset & 0xff000000) >> 24);
+    as<uint32>(iv.raw + 12) = offset;
+    auto key = as<UInt256>(cdn_encryption_key_.c_str());
+
+    AesCtrState ctr_state;
+    ctr_state.init(key, iv);
+    ctr_state.decrypt(bytes.as_slice(), bytes.as_slice());
+  }
+  if (!encryption_key_.empty()) {
+    CHECK(next_part_ == part.id) << tag("expected part.id", next_part_) << "!=" << tag("part.id", part.id);
+    CHECK(!next_part_stop_);
+    next_part_++;
+    if (part.size % 16 != 0) {
+      next_part_stop_ = true;
+    }
+    aes_ige_decrypt(encryption_key_.key(), &encryption_key_.mutable_iv(), bytes.as_slice(), bytes.as_slice());
+  }
+
+  auto slice = bytes.as_slice().truncate(part.size);
+  TRY_STATUS(acquire_fd());
+  TRY_RESULT(written, fd_.pwrite(slice, part.offset));
+  // may write less than part.size, when size of downloadable file is unknown
+  if (written != slice.size()) {
+    return Status::Error("Failed to save file part to the file");
+  }
+  return written;
+}
+void FileDownloader::on_progress(int32 part_count, int32 part_size, int32 ready_part_count, bool is_ready,
+                                 int64 ready_size) {
+  if (is_ready) {
+    // do not send partial location. will lead to wrong local_size
+    return;
+  }
+  if (ready_size == 0 || path_.empty()) {
+    return;
+  }
+  if (encryption_key_.empty()) {
+    callback_->on_partial_download(PartialLocalFileLocation{remote_.file_type_, path_, part_size, ready_part_count, ""},
+                                   ready_size);
+  } else {
+    UInt256 iv;
+    if (ready_part_count == next_part_) {
+      iv = encryption_key_.mutable_iv();
+    } else {
+      LOG(FATAL) << tag("ready_part_count", ready_part_count) << tag("next_part", next_part_);
+    }
+    callback_->on_partial_download(PartialLocalFileLocation{remote_.file_type_, path_, part_size, ready_part_count,
+                                                            Slice(iv.raw, sizeof(iv)).str()},
+                                   ready_size);
+  }
+}
+
+FileLoader::Callback *FileDownloader::get_callback() {
+  return static_cast<FileLoader::Callback *>(callback_.get());
+}
+
+Status FileDownloader::process_check_query(NetQueryPtr net_query) {
+  has_hash_query_ = false;
+  TRY_RESULT(file_hashes, fetch_result<telegram_api::upload_getCdnFileHashes>(std::move(net_query)));
+  add_hash_info(file_hashes);
+  return Status::OK();
+}
+Result<FileLoader::CheckInfo> FileDownloader::check_loop(int64 checked_prefix_size, int64 ready_prefix_size,
+                                                         bool is_ready) {
+  if (!need_check_) {
+    return CheckInfo{};
+  }
+  SCOPE_EXIT {
+    try_release_fd();
+  };
+  CheckInfo info;
+  while (checked_prefix_size < ready_prefix_size) {
+    //LOG(ERROR) << "NEED TO CHECK: " << checked_prefix_size << "->" << ready_prefix_size - checked_prefix_size;
+    HashInfo search_info;
+    search_info.offset = checked_prefix_size;
+    auto it = hash_info_.upper_bound(search_info);
+    if (it != hash_info_.begin()) {
+      it--;
+    }
+    if (it != hash_info_.end() && it->offset <= checked_prefix_size &&
+        it->offset + narrow_cast<int64>(it->size) > checked_prefix_size) {
+      int64 begin_offset = it->offset;
+      int64 end_offset = it->offset + narrow_cast<int64>(it->size);
+      if (ready_prefix_size < end_offset) {
+        if (!is_ready) {
+          break;
+        }
+        end_offset = ready_prefix_size;
+      }
+      size_t size = narrow_cast<size_t>(end_offset - begin_offset);
+      auto slice = BufferSlice(size);
+      TRY_STATUS(acquire_fd());
+      TRY_RESULT(read_size, fd_.pread(slice.as_slice(), begin_offset));
+      if (size != read_size) {
+        return Status::Error("Failed to read file to check hash");
+      }
+      string hash(32, ' ');
+      sha256(slice.as_slice(), hash);
+
+      if (hash != it->hash) {
+        if (only_check_) {
+          return Status::Error("FILE_DOWNLOAD_RESTART");
+        }
+        return Status::Error("Hash mismatch");
+      }
+
+      checked_prefix_size = end_offset;
+      info.changed = true;
+      continue;
+    }
+    if (!has_hash_query_) {
+      has_hash_query_ = true;
+      auto query =
+          telegram_api::upload_getFileHashes(remote_.as_input_file_location(), narrow_cast<int32>(checked_prefix_size));
+      auto net_query = G()->net_query_creator().create(
+          create_storer(query), remote_.get_dc_id(),
+          is_small_ ? NetQuery::Type::DownloadSmall : NetQuery::Type::Download, NetQuery::AuthFlag::On);
+      info.queries.push_back(std::move(net_query));
+      break;
+    }
+    // Should fail?
+    break;
+  }
+  info.need_check = need_check_;
+  info.checked_prefix_size = checked_prefix_size;
+  return std::move(info);
+}
+void FileDownloader::add_hash_info(const std::vector<telegram_api::object_ptr<telegram_api::fileHash>> &hashes) {
+  for (auto &hash : hashes) {
+    //LOG(ERROR) << "ADD HASH " << hash->offset_ << "->" << hash->limit_;
+    HashInfo hash_info;
+    hash_info.size = hash->limit_;
+    hash_info.offset = hash->offset_;
+    hash_info.hash = hash->hash_.as_slice().str();
+    hash_info_.insert(std::move(hash_info));
+  }
+}
+
+void FileDownloader::keep_fd_flag(bool keep_fd) {
+  keep_fd_ = keep_fd;
+  try_release_fd();
+}
+
+void FileDownloader::try_release_fd() {
+  if (!keep_fd_ && !fd_.empty()) {
+    fd_.close();
+  }
+}
+
+Status FileDownloader::acquire_fd() {
+  if (fd_.empty()) {
+    if (path_.empty()) {
+      TRY_RESULT(file_path, open_temp_file(remote_.file_type_));
+      std::tie(fd_, path_) = std::move(file_path);
+    } else {
+      TRY_RESULT(fd, FileFd::open(path_, (only_check_ ? 0 : FileFd::Write) | FileFd::Read));
+      fd_ = std::move(fd);
+    }
+  }
+  return Status::OK();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileDownloader.h b/libs/tdlib/td/td/telegram/files/FileDownloader.h
new file mode 100644
index 0000000000..6a45ca567b
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileDownloader.h
@@ -0,0 +1,100 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/files/FileLoader.h"
+#include "td/telegram/files/FileLocation.h"
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/utils/common.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/Status.h"
+
+#include <map>
+#include <set>
+#include <utility>
+
+namespace td {
+class FileDownloader : public FileLoader {
+ public:
+  class Callback : public FileLoader::Callback {
+   public:
+    virtual void on_start_download() = 0;
+    virtual void on_partial_download(const PartialLocalFileLocation &partial_local, int64 ready_size) = 0;
+    virtual void on_ok(const FullLocalFileLocation &full_local, int64 size) = 0;
+    virtual void on_error(Status status) = 0;
+  };
+
+  FileDownloader(const FullRemoteFileLocation &remote, const LocalFileLocation &local, int64 size, string name,
+                 const FileEncryptionKey &encryption_key, bool is_small, bool search_file,
+                 std::unique_ptr<Callback> callback);
+
+  // Should just implement all parent pure virtual methods.
+  // Must not call any of them...
+ private:
+  enum class QueryType : uint8 { Default = 1, CDN, ReuploadCDN };
+  ResourceState resource_state_;
+  FullRemoteFileLocation remote_;
+  LocalFileLocation local_;
+  int64 size_;
+  string name_;
+  FileEncryptionKey encryption_key_;
+  std::unique_ptr<Callback> callback_;
+  bool only_check_{false};
+
+  string path_;
+  FileFd fd_;
+
+  int32 next_part_ = 0;
+  bool next_part_stop_ = false;
+  bool is_small_;
+  bool search_file_{false};
+
+  bool use_cdn_ = false;
+  DcId cdn_dc_id_;
+  string cdn_encryption_key_;
+  string cdn_encryption_iv_;
+  string cdn_file_token_;
+  int32 cdn_file_token_generation_{0};
+  std::map<int32, string> cdn_part_reupload_token_;
+  std::map<int32, int32> cdn_part_file_token_generation_;
+
+  bool need_check_{false};
+  struct HashInfo {
+    int64 offset;
+    size_t size;
+    string hash;
+    bool operator<(const HashInfo &other) const {
+      return offset < other.offset;
+    }
+  };
+  std::set<HashInfo> hash_info_;
+  bool has_hash_query_ = false;
+
+  Result<FileInfo> init() override TD_WARN_UNUSED_RESULT;
+  Status on_ok(int64 size) override TD_WARN_UNUSED_RESULT;
+  void on_error(Status status) override;
+  Result<bool> should_restart_part(Part part, NetQueryPtr &net_query) override TD_WARN_UNUSED_RESULT;
+  Result<std::pair<NetQueryPtr, bool>> start_part(Part part, int32 part_count) override TD_WARN_UNUSED_RESULT;
+  Result<size_t> process_part(Part part, NetQueryPtr net_query) override TD_WARN_UNUSED_RESULT;
+  void on_progress(int32 part_count, int32 part_size, int32 ready_part_count, bool is_ready, int64 ready_size) override;
+  FileLoader::Callback *get_callback() override;
+  Status process_check_query(NetQueryPtr net_query) override;
+  Result<CheckInfo> check_loop(int64 checked_prefix_size, int64 ready_prefix_size, bool is_ready) override;
+  void add_hash_info(const std::vector<telegram_api::object_ptr<telegram_api::fileHash>> &hashes);
+
+  bool keep_fd_ = false;
+  void keep_fd_flag(bool keep_fd) override;
+  void try_release_fd();
+  Status acquire_fd() TD_WARN_UNUSED_RESULT;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileFromBytes.cpp b/libs/tdlib/td/td/telegram/files/FileFromBytes.cpp
new file mode 100644
index 0000000000..939803d8a8
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileFromBytes.cpp
@@ -0,0 +1,50 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/files/FileFromBytes.h"
+
+#include "td/telegram/files/FileLoaderUtils.h"
+#include "td/telegram/Global.h"
+
+#include "td/utils/common.h"
+#include "td/utils/misc.h"
+
+#include <tuple>
+
+namespace td {
+
+FileFromBytes::FileFromBytes(FileType type, BufferSlice bytes, string name, std::unique_ptr<Callback> callback)
+    : type_(type), bytes_(std::move(bytes)), name_(std::move(name)), callback_(std::move(callback)) {
+}
+
+void FileFromBytes::wakeup() {
+  auto r_fd_path = open_temp_file(type_);
+  if (r_fd_path.is_error()) {
+    return callback_->on_error(r_fd_path.move_as_error());
+  }
+  FileFd fd;
+  string path;
+  std::tie(fd, path) = r_fd_path.move_as_ok();
+
+  auto r_size = fd.write(bytes_.as_slice());
+  if (r_size.is_error()) {
+    return callback_->on_error(r_size.move_as_error());
+  }
+  fd.close();
+  auto size = r_size.ok();
+  if (size != bytes_.size()) {
+    return callback_->on_error(Status::Error("Failed to write bytes to the file"));
+  }
+
+  auto dir = get_files_dir(type_);
+  auto r_perm_path = create_from_temp(path, dir, name_);
+  if (r_perm_path.is_error()) {
+    return callback_->on_error(r_perm_path.move_as_error());
+  }
+  callback_->on_ok(FullLocalFileLocation(type_, r_perm_path.move_as_ok(), 0), narrow_cast<int64>(bytes_.size()));
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileFromBytes.h b/libs/tdlib/td/td/telegram/files/FileFromBytes.h
new file mode 100644
index 0000000000..23f4b2ff4f
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileFromBytes.h
@@ -0,0 +1,54 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+
+#include "td/telegram/files/FileLoader.h"
+#include "td/telegram/files/FileLocation.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/Status.h"
+
+namespace td {
+class FileFromBytes : public FileLoaderActor {
+ public:
+  class Callback {
+   public:
+    Callback() = default;
+    Callback(const Callback &) = delete;
+    Callback &operator=(const Callback &) = delete;
+    virtual ~Callback() = default;
+    virtual void on_ok(const FullLocalFileLocation &full_local, int64 size) = 0;
+    virtual void on_error(Status status) = 0;
+  };
+
+  FileFromBytes(FileType type, BufferSlice bytes, string name, std::unique_ptr<Callback> callback);
+
+  // Should just implement all parent pure virtual methods.
+  // Must not call any of them...
+ private:
+  FileType type_;
+  BufferSlice bytes_;
+  string name_;
+
+  std::unique_ptr<Callback> callback_;
+
+  FileFd fd_;
+  string path_;
+
+  void wakeup() override;
+  void set_resource_manager(ActorShared<ResourceManager>) override {
+  }
+  void update_priority(int8 priority) override {
+  }
+  void update_resources(const ResourceState &other) override {
+  }
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileGcParameters.cpp b/libs/tdlib/td/td/telegram/files/FileGcParameters.cpp
new file mode 100644
index 0000000000..7b949d73a2
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileGcParameters.cpp
@@ -0,0 +1,32 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/files/FileGcParameters.h"
+
+#include "td/telegram/ConfigShared.h"
+#include "td/telegram/Global.h"
+
+namespace td {
+FileGcParameters::FileGcParameters(int64 size, int32 ttl, int32 count, int32 immunity_delay,
+                                   vector<FileType> file_types, vector<DialogId> owner_dialog_ids,
+                                   vector<DialogId> exclude_owner_dialog_ids, int32 dialog_limit)
+    : file_types(std::move(file_types))
+    , owner_dialog_ids(std::move(owner_dialog_ids))
+    , exclude_owner_dialog_ids(std::move(exclude_owner_dialog_ids))
+    , dialog_limit(dialog_limit) {
+  auto &config = G()->shared_config();
+  this->max_files_size =
+      size >= 0 ? size : static_cast<int64>(config.get_option_integer("storage_max_files_size", 100 << 10)) << 10;
+
+  this->max_time_from_last_access =
+      ttl >= 0 ? ttl : config.get_option_integer("storage_max_time_from_last_access", 60 * 60 * 23);
+
+  this->max_file_count = count >= 0 ? count : config.get_option_integer("storage_max_file_count", 40000);
+
+  this->immunity_delay =
+      immunity_delay >= 0 ? immunity_delay : config.get_option_integer("storage_immunity_delay", 60 * 60);
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileGcParameters.h b/libs/tdlib/td/td/telegram/files/FileGcParameters.h
new file mode 100644
index 0000000000..a0c3c35524
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileGcParameters.h
@@ -0,0 +1,34 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/DialogId.h"
+#include "td/telegram/files/FileLocation.h"
+
+#include "td/utils/common.h"
+
+namespace td {
+
+struct FileGcParameters {
+  FileGcParameters() : FileGcParameters(-1, -1, -1, -1, {}, {}, {}, 0) {
+  }
+  FileGcParameters(int64 size, int32 ttl, int32 count, int32 immunity_delay, vector<FileType> file_types,
+                   vector<DialogId> owner_dialog_ids, vector<DialogId> exclude_owner_dialog_ids, int32 dialog_limit);
+
+  int64 max_files_size;
+  uint32 max_time_from_last_access;
+  uint32 max_file_count;
+  uint32 immunity_delay;
+
+  vector<FileType> file_types;
+  vector<DialogId> owner_dialog_ids;
+  vector<DialogId> exclude_owner_dialog_ids;
+
+  int32 dialog_limit;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileGcWorker.cpp b/libs/tdlib/td/td/telegram/files/FileGcWorker.cpp
new file mode 100644
index 0000000000..35dce38e9c
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileGcWorker.cpp
@@ -0,0 +1,174 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/files/FileGcWorker.h"
+
+#include "td/telegram/files/FileManager.h"
+#include "td/telegram/Global.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/Clocks.h"
+#include "td/utils/port/path.h"
+#include "td/utils/Time.h"
+
+#include <algorithm>
+#include <array>
+
+namespace td {
+void FileGcWorker::do_remove_file(const FullFileInfo &info) {
+  // LOG(WARNING) << "Gc remove file: " << tag("path", file) << tag("mtime", stat.mtime_nsec_ / 1000000000)
+  // << tag("atime", stat.atime_nsec_ / 1000000000);
+  // TODO: remove file from db too.
+  auto status = unlink(info.path);
+  LOG_IF(WARNING, status.is_error()) << "Failed to unlink file during files gc: " << status;
+  send_closure(G()->file_manager(), &FileManager::on_file_unlink,
+               FullLocalFileLocation(info.file_type, info.path, info.mtime_nsec));
+}
+
+void FileGcWorker::run_gc(const FileGcParameters &parameters, std::vector<FullFileInfo> files,
+                          Promise<FileStats> promise) {
+  auto begin_time = Time::now();
+  LOG(INFO) << "Start files gc";
+  // quite stupid implementations
+  // needs a lot of memory
+  // may write something more clever, but i will need at least 2 passes over the files
+  // TODO update atime for all files in android (?)
+
+  std::array<bool, file_type_size> immune_types{{false}};
+
+  if (G()->parameters().use_file_db) {
+    // immune by default
+    immune_types[narrow_cast<size_t>(FileType::Sticker)] = true;
+    immune_types[narrow_cast<size_t>(FileType::ProfilePhoto)] = true;
+    immune_types[narrow_cast<size_t>(FileType::Thumbnail)] = true;
+    immune_types[narrow_cast<size_t>(FileType::Wallpaper)] = true;
+  }
+
+  if (!parameters.file_types.empty()) {
+    std::fill(immune_types.begin(), immune_types.end(), true);
+    for (auto file_type : parameters.file_types) {
+      immune_types[narrow_cast<size_t>(file_type)] = false;
+    }
+  }
+
+  if (G()->parameters().use_file_db) {
+    immune_types[narrow_cast<size_t>(FileType::EncryptedThumbnail)] = true;
+  }
+
+  auto file_cnt = files.size();
+  int32 type_immunity_ignored_cnt = 0;
+  int32 time_immunity_ignored_cnt = 0;
+  int32 exclude_owner_dialog_id_ignored_cnt = 0;
+  int32 owner_dialog_id_ignored_cnt = 0;
+  int32 remove_by_atime_cnt = 0;
+  int32 remove_by_count_cnt = 0;
+  int32 remove_by_size_cnt = 0;
+  int64 total_removed_size = 0;
+  int64 total_size = 0;
+  for (auto &info : files) {
+    if (info.atime_nsec < info.mtime_nsec) {
+      info.atime_nsec = info.mtime_nsec;
+    }
+    total_size += info.size;
+  }
+
+  FileStats new_stats;
+  new_stats.split_by_owner_dialog_id = parameters.dialog_limit != 0;
+
+  // Remove all files with atime > now - max_time_from_last_access
+  double now = Clocks::system();
+  files.erase(
+      std::remove_if(
+          files.begin(), files.end(),
+          [&](const FullFileInfo &info) {
+            if (immune_types[narrow_cast<size_t>(info.file_type)]) {
+              type_immunity_ignored_cnt++;
+              new_stats.add(FullFileInfo(info));
+              return true;
+            }
+            if (std::find(parameters.exclude_owner_dialog_ids.begin(), parameters.exclude_owner_dialog_ids.end(),
+                          info.owner_dialog_id) != parameters.exclude_owner_dialog_ids.end()) {
+              exclude_owner_dialog_id_ignored_cnt++;
+              new_stats.add(FullFileInfo(info));
+              return true;
+            }
+            if (!parameters.owner_dialog_ids.empty() &&
+                std::find(parameters.owner_dialog_ids.begin(), parameters.owner_dialog_ids.end(),
+                          info.owner_dialog_id) == parameters.owner_dialog_ids.end()) {
+              owner_dialog_id_ignored_cnt++;
+              new_stats.add(FullFileInfo(info));
+              return true;
+            }
+            if (static_cast<double>(info.mtime_nsec / 1000000000) > now - parameters.immunity_delay) {
+              // new files are immune to gc.
+              time_immunity_ignored_cnt++;
+              new_stats.add(FullFileInfo(info));
+              return true;
+            }
+
+            if (static_cast<double>(info.atime_nsec / 1000000000) < now - parameters.max_time_from_last_access) {
+              do_remove_file(info);
+              total_removed_size += info.size;
+              remove_by_atime_cnt++;
+              return true;
+            }
+            return false;
+          }),
+      files.end());
+
+  // sort by max(atime, mtime)
+  std::sort(files.begin(), files.end(), [](const auto &a, const auto &b) { return a.atime_nsec < b.atime_nsec; });
+
+  // 1. Total memory must be less than max_memory
+  // 2. Total file count must be less than MAX_FILE_COUNT
+  size_t remove_count = 0;
+  if (files.size() > parameters.max_file_count) {
+    remove_count = files.size() - parameters.max_file_count;
+  }
+  int64 remove_size = -parameters.max_files_size;
+  for (auto &file : files) {
+    remove_size += file.size;
+  }
+
+  size_t pos = 0;
+  while (pos < files.size() && (remove_count > 0 || remove_size > 0)) {
+    if (remove_count > 0) {
+      remove_by_count_cnt++;
+    } else {
+      remove_by_size_cnt++;
+    }
+
+    if (remove_count > 0) {
+      remove_count--;
+    }
+    remove_size -= files[pos].size;
+
+    total_removed_size += files[pos].size;
+    do_remove_file(files[pos]);
+    pos++;
+  }
+
+  while (pos < files.size()) {
+    new_stats.add(std::move(files[pos]));
+    pos++;
+  }
+
+  auto end_time = Time::now();
+
+  LOG(INFO) << "Finish files gc: " << tag("time", end_time - begin_time) << tag("total", file_cnt)
+            << tag("removed", remove_by_atime_cnt + remove_by_count_cnt + remove_by_size_cnt)
+            << tag("total_size", format::as_size(total_size))
+            << tag("total_removed_size", format::as_size(total_removed_size)) << tag("by_atime", remove_by_atime_cnt)
+            << tag("by_count", remove_by_count_cnt) << tag("by_size", remove_by_size_cnt)
+            << tag("type_immunity", type_immunity_ignored_cnt) << tag("time_immunity", time_immunity_ignored_cnt)
+            << tag("owner_dialog_id_immunity", owner_dialog_id_ignored_cnt)
+            << tag("exclude_owner_dialog_id_immunity", exclude_owner_dialog_id_ignored_cnt);
+
+  promise.set_value(std::move(new_stats));
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileGcWorker.h b/libs/tdlib/td/td/telegram/files/FileGcWorker.h
new file mode 100644
index 0000000000..7e83d9fa98
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileGcWorker.h
@@ -0,0 +1,28 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/files/FileGcParameters.h"
+#include "td/telegram/files/FileLocation.h"
+#include "td/telegram/files/FileStats.h"
+
+namespace td {
+class FileGcWorker : public Actor {
+ public:
+  explicit FileGcWorker(ActorShared<> parent) : parent_(std::move(parent)) {
+  }
+  void run_gc(const FileGcParameters &parameters, std::vector<FullFileInfo> files, Promise<FileStats> promise);
+
+ private:
+  ActorShared<> parent_;
+  void do_remove_file(const FullFileInfo &info);
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileGenerateManager.cpp b/libs/tdlib/td/td/telegram/files/FileGenerateManager.cpp
new file mode 100644
index 0000000000..22472a248f
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileGenerateManager.cpp
@@ -0,0 +1,285 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/files/FileGenerateManager.h"
+
+#include "td/telegram/td_api.h"
+
+#include "td/telegram/files/FileId.h"
+#include "td/telegram/files/FileLoaderUtils.h"
+#include "td/telegram/files/FileManager.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/Td.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/path.h"
+#include "td/utils/Slice.h"
+
+#include <utility>
+
+namespace td {
+
+class FileGenerateActor : public Actor {
+ public:
+  FileGenerateActor() = default;
+  FileGenerateActor(const FileGenerateActor &) = delete;
+  FileGenerateActor &operator=(const FileGenerateActor &) = delete;
+  FileGenerateActor(FileGenerateActor &&) = delete;
+  FileGenerateActor &operator=(FileGenerateActor &&) = delete;
+  ~FileGenerateActor() override = default;
+  virtual void file_generate_progress(int32 expected_size, int32 local_prefix_size, Promise<> promise) = 0;
+  virtual void file_generate_finish(Status status, Promise<> promise) = 0;
+};
+
+class FileDownloadGenerateActor : public FileGenerateActor {
+ public:
+  FileDownloadGenerateActor(FileType file_type, FileId file_id, std::unique_ptr<FileGenerateCallback> callback,
+                            ActorShared<> parent)
+      : file_type_(file_type), file_id_(file_id), callback_(std::move(callback)), parent_(std::move(parent)) {
+  }
+  void file_generate_progress(int32 expected_size, int32 local_prefix_size, Promise<> promise) override {
+    UNREACHABLE();
+  }
+  void file_generate_finish(Status status, Promise<> promise) override {
+    UNREACHABLE();
+  }
+
+ private:
+  FileType file_type_;
+  FileId file_id_;
+  std::unique_ptr<FileGenerateCallback> callback_;
+  ActorShared<> parent_;
+
+  void start_up() override {
+    LOG(INFO) << "DOWNLOAD " << file_id_;
+    class Callback : public FileManager::DownloadCallback {
+     public:
+      explicit Callback(ActorId<FileDownloadGenerateActor> parent) : parent_(std::move(parent)) {
+      }
+
+      // TODO: upload during download
+
+      void on_download_ok(FileId file_id) override {
+        send_closure(parent_, &FileDownloadGenerateActor::on_download_ok);
+      }
+      void on_download_error(FileId file_id, Status error) override {
+        send_closure(parent_, &FileDownloadGenerateActor::on_download_error, std::move(error));
+      }
+
+     private:
+      ActorId<FileDownloadGenerateActor> parent_;
+    };
+
+    send_closure(G()->file_manager(), &FileManager::download, file_id_, std::make_unique<Callback>(actor_id(this)), 1);
+  }
+  void hangup() override {
+    send_closure(G()->file_manager(), &FileManager::download, file_id_, nullptr, 0);
+    stop();
+  }
+
+  void on_download_ok() {
+    send_lambda(G()->file_manager(), [file_type = file_type_, file_id = file_id_, callback = std::move(callback_)] {
+      auto file_view = G()->td().get_actor_unsafe()->file_manager_->get_file_view(file_id);
+      if (file_view.has_local_location()) {
+        auto location = file_view.local_location();
+        location.file_type_ = file_type;
+        callback->on_ok(location);
+      } else {
+        LOG(ERROR) << "Expected to have local location";
+        callback->on_error(Status::Error("Unknown"));
+      }
+    });
+    stop();
+  }
+  void on_download_error(Status error) {
+    callback_->on_error(std::move(error));
+    stop();
+  }
+};
+
+class FileExternalGenerateActor : public FileGenerateActor {
+ public:
+  FileExternalGenerateActor(uint64 query_id, const FullGenerateFileLocation &generate_location,
+                            const LocalFileLocation &local_location, string name,
+                            std::unique_ptr<FileGenerateCallback> callback, ActorShared<> parent)
+      : query_id_(query_id)
+      , generate_location_(generate_location)
+      , local_(local_location)
+      , name_(std::move(name))
+      , callback_(std::move(callback))
+      , parent_(std::move(parent)) {
+  }
+
+  void file_generate_progress(int32 expected_size, int32 local_prefix_size, Promise<> promise) override {
+    check_status(do_file_generate_progress(expected_size, local_prefix_size), std::move(promise));
+  }
+  void file_generate_finish(Status status, Promise<> promise) override {
+    check_status(do_file_generate_finish(std::move(status)), std::move(promise));
+  }
+
+ private:
+  uint64 query_id_;
+  FullGenerateFileLocation generate_location_;
+  LocalFileLocation local_;
+  string name_;
+  string path_;
+  std::unique_ptr<FileGenerateCallback> callback_;
+  ActorShared<> parent_;
+
+  void start_up() override {
+    if (local_.type() == LocalFileLocation::Type::Full) {
+      callback_->on_ok(local_.full());
+      callback_.reset();
+      return stop();
+    }
+
+    if (local_.type() == LocalFileLocation::Type::Partial) {
+      const auto &partial = local_.partial();
+      path_ = partial.path_;
+      LOG(INFO) << "Unlink partially generated file at " << path_;
+      unlink(path_).ignore();
+    } else {
+      auto r_file_path = open_temp_file(generate_location_.file_type_);
+      if (r_file_path.is_error()) {
+        return check_status(r_file_path.move_as_error());
+      }
+      auto file_path = r_file_path.move_as_ok();
+      file_path.first.close();
+      path_ = file_path.second;
+    }
+    send_closure(
+        G()->td(), &Td::send_update,
+        make_tl_object<td_api::updateFileGenerationStart>(
+            static_cast<int64>(query_id_), generate_location_.original_path_, path_, generate_location_.conversion_));
+  }
+  void hangup() override {
+    check_status(Status::Error(1, "Cancelled"));
+  }
+
+  Status do_file_generate_progress(int32 expected_size, int32 local_prefix_size) {
+    if (local_prefix_size < 0) {
+      return Status::Error(1, "Invalid local prefix size");
+    }
+    callback_->on_partial_generate(
+        PartialLocalFileLocation{generate_location_.file_type_, path_, 1, local_prefix_size, ""}, expected_size);
+    return Status::OK();
+  }
+
+  Status do_file_generate_finish(Status status) {
+    TRY_STATUS(std::move(status));
+
+    auto dir = get_files_dir(generate_location_.file_type_);
+
+    TRY_RESULT(perm_path, create_from_temp(path_, dir, name_));
+    callback_->on_ok(FullLocalFileLocation(generate_location_.file_type_, std::move(perm_path), 0));
+    callback_.reset();
+    stop();
+    return Status::OK();
+  }
+
+  void check_status(Status status, Promise<> promise = Promise<>()) {
+    if (promise) {
+      if (status.is_ok() || status.code() == 1) {
+        promise.set_value(Unit());
+      } else {
+        promise.set_error(Status::Error(400, status.message()));
+      }
+    }
+
+    if (status.is_error()) {
+      LOG(INFO) << "Unlink partially generated file at " << path_ << " because of " << status;
+      unlink(path_).ignore();
+      callback_->on_error(std::move(status));
+      callback_.reset();
+      stop();
+    }
+  }
+
+  void tear_down() override {
+    send_closure(G()->td(), &Td::send_update,
+                 make_tl_object<td_api::updateFileGenerationStop>(static_cast<int64>(query_id_)));
+  }
+};
+
+FileGenerateManager::Query::~Query() = default;
+FileGenerateManager::Query::Query(Query &&other) = default;
+FileGenerateManager::Query &FileGenerateManager::Query::operator=(Query &&other) = default;
+
+void FileGenerateManager::generate_file(uint64 query_id, const FullGenerateFileLocation &generate_location,
+                                        const LocalFileLocation &local_location, string name,
+                                        std::unique_ptr<FileGenerateCallback> callback) {
+  CHECK(query_id != 0);
+  auto it_flag = query_id_to_query_.insert(std::make_pair(query_id, Query{}));
+  CHECK(it_flag.second) << "Query id must be unique";
+  auto parent = actor_shared(this, query_id);
+
+  Slice file_id_query = "#file_id#";
+  Slice conversion = generate_location.conversion_;
+
+  auto &query = it_flag.first->second;
+  if (conversion.copy().truncate(file_id_query.size()) == file_id_query) {
+    auto file_id = FileId(to_integer<int32>(conversion.substr(file_id_query.size())), 0);
+    query.worker_ = create_actor<FileDownloadGenerateActor>("FileDownloadGenerateActor", generate_location.file_type_,
+                                                            file_id, std::move(callback), std::move(parent));
+  } else {
+    query.worker_ = create_actor<FileExternalGenerateActor>("FileExternalGenerationActor", query_id, generate_location,
+                                                            local_location, std::move(name), std::move(callback),
+                                                            std::move(parent));
+  }
+}
+
+void FileGenerateManager::cancel(uint64 query_id) {
+  auto it = query_id_to_query_.find(query_id);
+  if (it == query_id_to_query_.end()) {
+    return;
+  }
+  it->second.worker_.reset();
+}
+
+void FileGenerateManager::external_file_generate_progress(uint64 query_id, int32 expected_size, int32 local_prefix_size,
+                                                          Promise<> promise) {
+  auto it = query_id_to_query_.find(query_id);
+  if (it == query_id_to_query_.end()) {
+    return promise.set_error(Status::Error(400, "Unknown generation_id"));
+  }
+  send_closure(it->second.worker_, &FileGenerateActor::file_generate_progress, expected_size, local_prefix_size,
+               std::move(promise));
+}
+
+void FileGenerateManager::external_file_generate_finish(uint64 query_id, Status status, Promise<> promise) {
+  auto it = query_id_to_query_.find(query_id);
+  if (it == query_id_to_query_.end()) {
+    return promise.set_error(Status::Error(400, "Unknown generation_id"));
+  }
+  send_closure(it->second.worker_, &FileGenerateActor::file_generate_finish, std::move(status), std::move(promise));
+}
+
+void FileGenerateManager::do_cancel(uint64 query_id) {
+  query_id_to_query_.erase(query_id);
+}
+
+void FileGenerateManager::hangup_shared() {
+  do_cancel(get_link_token());
+  loop();
+}
+
+void FileGenerateManager::hangup() {
+  close_flag_ = true;
+  for (auto &it : query_id_to_query_) {
+    it.second.worker_.reset();
+  }
+  loop();
+}
+
+void FileGenerateManager::loop() {
+  if (close_flag_ && query_id_to_query_.empty()) {
+    stop();
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileGenerateManager.h b/libs/tdlib/td/td/telegram/files/FileGenerateManager.h
new file mode 100644
index 0000000000..4acd495d72
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileGenerateManager.h
@@ -0,0 +1,70 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/files/FileLocation.h"
+
+#include "td/utils/Status.h"
+
+#include <map>
+
+namespace td {
+class FileGenerateActor;
+
+class FileGenerateCallback {
+ public:
+  FileGenerateCallback() = default;
+  FileGenerateCallback(const FileGenerateCallback &) = delete;
+  FileGenerateCallback &operator=(const FileGenerateCallback &) = delete;
+  virtual ~FileGenerateCallback() = default;
+
+  virtual void on_partial_generate(const PartialLocalFileLocation &partial_local, int32 expected_size) = 0;
+  virtual void on_ok(const FullLocalFileLocation &local) = 0;
+  virtual void on_error(Status error) = 0;
+};
+
+class FileGenerateManager : public Actor {
+ public:
+  explicit FileGenerateManager(ActorShared<> parent) : parent_(std::move(parent)) {
+  }
+
+  void generate_file(uint64 query_id, const FullGenerateFileLocation &generate_location,
+                     const LocalFileLocation &local_location, string name,
+                     std::unique_ptr<FileGenerateCallback> callback);
+  void cancel(uint64 query_id);
+
+  // external updates about file generation state
+  void external_file_generate_progress(uint64 query_id, int32 expected_size, int32 local_prefix_size,
+                                       Promise<> promise);
+  void external_file_generate_finish(uint64 query_id, Status status, Promise<> promise);
+
+ private:
+  struct Query {
+    Query() = default;
+    Query(const Query &other) = delete;
+    Query &operator=(const Query &other) = delete;
+    Query(Query &&other);
+    Query &operator=(Query &&other);
+    ~Query();
+
+    ActorOwn<FileGenerateActor> worker_;
+  };
+
+  ActorShared<> parent_;
+  std::map<uint64, Query> query_id_to_query_;
+  bool close_flag_ = false;
+
+  void hangup() override;
+  void hangup_shared() override;
+  void loop() override;
+  void do_cancel(uint64 query_id);
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileHashUploader.cpp b/libs/tdlib/td/td/telegram/files/FileHashUploader.cpp
new file mode 100644
index 0000000000..2408e16df4
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileHashUploader.cpp
@@ -0,0 +1,142 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/files/FileHashUploader.h"
+
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/Global.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/crypto.h"
+#include "td/utils/logging.h"
+#include "td/utils/MimeType.h"
+#include "td/utils/misc.h"
+#include "td/utils/PathView.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/Status.h"
+
+namespace td {
+void FileHashUploader::start_up() {
+  auto status = init();
+  if (status.is_error()) {
+    callback_->on_error(std::move(status));
+    stop_flag_ = true;
+    return;
+  }
+}
+Status FileHashUploader::init() {
+  TRY_RESULT(fd, FileFd::open(local_.path_, FileFd::Read));
+  if (fd.get_size() != size_) {
+    return Status::Error("size mismatch");
+  }
+  fd_ = BufferedFd<FileFd>(std::move(fd));
+  sha256_init(&sha256_state_);
+
+  resource_state_.set_unit_size(1024);
+  resource_state_.update_estimated_limit(size_);
+  return Status::OK();
+}
+void FileHashUploader::loop() {
+  if (stop_flag_) {
+    return;
+  }
+
+  auto status = loop_impl();
+  if (status.is_error()) {
+    callback_->on_error(std::move(status));
+    stop_flag_ = true;
+    return;
+  }
+}
+
+Status FileHashUploader::loop_impl() {
+  if (state_ == CalcSha) {
+    TRY_STATUS(loop_sha());
+  }
+  if (state_ == NetRequest) {
+    // messages.getDocumentByHash#338e2464 sha256:bytes size:int mime_type:string = Document;
+    auto hash = BufferSlice(32);
+    sha256_final(&sha256_state_, hash.as_slice());
+    auto mime_type = MimeType::from_extension(PathView(local_.path_).extension(), "image/gif");
+    auto query =
+        telegram_api::messages_getDocumentByHash(std::move(hash), static_cast<int32>(size_), std::move(mime_type));
+    LOG(INFO) << "Send getDocumentByHash request: " << to_string(query);
+    auto ptr = G()->net_query_creator().create(create_storer(query));
+    G()->net_query_dispatcher().dispatch_with_callback(std::move(ptr), actor_shared(this));
+    state_ = WaitNetResult;
+  }
+  return Status::OK();
+}
+
+Status FileHashUploader::loop_sha() {
+  auto limit = resource_state_.unused();
+  if (limit == 0) {
+    return Status::OK();
+  }
+  if (limit > size_left_) {
+    limit = size_left_;
+  }
+  resource_state_.start_use(limit);
+
+  fd_.update_flags(Fd::Flag::Read);
+  TRY_RESULT(read_size, fd_.flush_read(static_cast<size_t>(limit)));
+  if (read_size != static_cast<size_t>(limit)) {
+    return Status::Error("unexpected end of file");
+  }
+  while (true) {
+    auto ready = fd_.input_buffer().prepare_read();
+    if (ready.empty()) {
+      break;
+    }
+    sha256_update(ready, &sha256_state_);
+    fd_.input_buffer().confirm_read(ready.size());
+  }
+  resource_state_.stop_use(limit);
+
+  size_left_ -= narrow_cast<int64>(read_size);
+  CHECK(size_left_ >= 0);
+  if (size_left_ == 0) {
+    state_ = NetRequest;
+    return Status::OK();
+  }
+  return Status::OK();
+}
+
+void FileHashUploader::on_result(NetQueryPtr net_query) {
+  auto status = on_result_impl(std::move(net_query));
+  if (status.is_error()) {
+    callback_->on_error(std::move(status));
+    stop_flag_ = true;
+    return;
+  }
+}
+
+Status FileHashUploader::on_result_impl(NetQueryPtr net_query) {
+  if (net_query->is_error()) {
+    return net_query->move_as_error();
+  }
+  TRY_RESULT(res, fetch_result<telegram_api::messages_getDocumentByHash>(net_query->ok()));
+
+  switch (res->get_id()) {
+    case telegram_api::documentEmpty::ID:
+      return Status::Error("Document is not found by hash");
+    case telegram_api::document::ID: {
+      auto document = move_tl_object_as<telegram_api::document>(res);
+      callback_->on_ok(FullRemoteFileLocation(FileType::Document, document->id_, document->access_hash_,
+                                              DcId::internal(document->dc_id_)));
+
+      stop_flag_ = true;
+      return Status::OK();
+    }
+    default:
+      UNREACHABLE();
+      return Status::Error("UNREACHABLE");
+  }
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileHashUploader.h b/libs/tdlib/td/td/telegram/files/FileHashUploader.h
new file mode 100644
index 0000000000..d836c521b7
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileHashUploader.h
@@ -0,0 +1,80 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/files/FileLoaderActor.h"
+#include "td/telegram/files/FileLocation.h"
+#include "td/telegram/files/ResourceManager.h"
+
+#include "td/utils/BufferedFd.h"
+#include "td/utils/crypto.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+class FileHashUploader : public FileLoaderActor {
+ public:
+  class Callback {
+   public:
+    Callback() = default;
+    Callback(const Callback &) = delete;
+    Callback &operator=(const Callback &) = delete;
+    virtual ~Callback() = default;
+    virtual void on_ok(const FullRemoteFileLocation &locatioin) = 0;
+    virtual void on_error(Status status) = 0;
+  };
+
+  FileHashUploader(const FullLocalFileLocation &local, int64 size, std::unique_ptr<Callback> callback)
+      : local_(local), size_(size), size_left_(size), callback_(std::move(callback)) {
+  }
+
+  void set_resource_manager(ActorShared<ResourceManager> resource_manager) override {
+    resource_manager_ = std::move(resource_manager);
+    send_closure(resource_manager_, &ResourceManager::update_resources, resource_state_);
+  }
+
+  void update_priority(int8 priority) override {
+    send_closure(resource_manager_, &ResourceManager::update_priority, priority);
+  }
+  void update_resources(const ResourceState &other) override {
+    if (stop_flag_) {
+      return;
+    }
+    resource_state_.update_slave(other);
+    loop();
+  }
+
+ private:
+  ResourceState resource_state_;
+  BufferedFd<FileFd> fd_;
+
+  FullLocalFileLocation local_;
+  int64 size_;
+  int64 size_left_;
+  unique_ptr<Callback> callback_;
+
+  ActorShared<ResourceManager> resource_manager_;
+
+  enum { CalcSha, NetRequest, WaitNetResult } state_ = CalcSha;
+  bool stop_flag_ = false;
+  Sha256State sha256_state_;
+
+  void start_up() override;
+  Status init();
+
+  void loop() override;
+
+  Status loop_impl();
+
+  Status loop_sha();
+
+  void on_result(NetQueryPtr net_query) override;
+
+  Status on_result_impl(NetQueryPtr net_query);
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileId.h b/libs/tdlib/td/td/telegram/files/FileId.h
new file mode 100644
index 0000000000..ef68681ba0
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileId.h
@@ -0,0 +1,67 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/StringBuilder.h"
+
+#include <functional>
+#include <type_traits>
+
+namespace td {
+
+class FileId {
+  int32 id = 0;
+  int32 remote_id = 0;
+
+ public:
+  FileId() = default;
+
+  FileId(int32 file_id, int32 remote_id) : id(file_id), remote_id(remote_id) {
+  }
+  template <class T1, class T2, typename = std::enable_if_t<std::is_convertible<T1, int32>::value>,
+            typename = std::enable_if_t<std::is_convertible<T2, int32>::value>>
+  FileId(T1 file_id, T2 remote_id) = delete;
+
+  bool empty() const {
+    return id <= 0;
+  }
+  bool is_valid() const {
+    return id > 0;
+  }
+
+  int32 get() const {
+    return id;
+  }
+
+  int32 get_remote() const {
+    return remote_id;
+  }
+
+  bool operator<(const FileId &other) const {
+    return id < other.id;
+  }
+
+  bool operator==(const FileId &other) const {
+    return id == other.id;
+  }
+
+  bool operator!=(const FileId &other) const {
+    return id != other.id;
+  }
+};
+
+struct FileIdHash {
+  std::size_t operator()(FileId file_id) const {
+    return std::hash<int32>()(file_id.get());
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &string_builder, FileId file_id) {
+  return string_builder << file_id.get() << "(" << file_id.get_remote() << ")";
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileId.hpp b/libs/tdlib/td/td/telegram/files/FileId.hpp
new file mode 100644
index 0000000000..b4b5dbf429
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileId.hpp
@@ -0,0 +1,26 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/files/FileId.h"
+
+#include "td/telegram/files/FileManager.hpp"
+#include "td/telegram/Td.h"
+
+namespace td {
+
+template <class StorerT>
+void store(const FileId &file_id, StorerT &storer) {
+  storer.context()->td().get_actor_unsafe()->file_manager_->store_file(file_id, storer);
+}
+
+template <class ParserT>
+void parse(FileId &file_id, ParserT &parser) {
+  file_id = parser.context()->td().get_actor_unsafe()->file_manager_->parse_file(parser);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileLoadManager.cpp b/libs/tdlib/td/td/telegram/files/FileLoadManager.cpp
new file mode 100644
index 0000000000..85ef83595d
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileLoadManager.cpp
@@ -0,0 +1,273 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/files/FileLoadManager.h"
+
+#include "td/telegram/Global.h"
+
+#include "td/utils/common.h"
+#include "td/utils/filesystem.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+
+namespace td {
+FileLoadManager::FileLoadManager(ActorShared<Callback> callback, ActorShared<> parent)
+    : callback_(std::move(callback)), parent_(std::move(parent)) {
+}
+
+void FileLoadManager::start_up() {
+  upload_resource_manager_ =
+      create_actor<ResourceManager>("UploadResourceManager", !G()->parameters().use_file_db /*tdlib_engine*/
+                                                                 ? ResourceManager::Mode::Greedy
+                                                                 : ResourceManager::Mode::Baseline);
+}
+
+ActorOwn<ResourceManager> &FileLoadManager::get_download_resource_manager(bool is_small, DcId dc_id) {
+  auto &actor = is_small ? download_small_resource_manager_map_[dc_id] : download_resource_manager_map_[dc_id];
+  if (actor.empty()) {
+    actor = create_actor<ResourceManager>(
+        PSLICE() << "DownloadResourceManager " << tag("is_small", is_small) << tag("dc_id", dc_id),
+        ResourceManager::Mode::Baseline);
+  }
+  return actor;
+}
+
+void FileLoadManager::download(QueryId id, const FullRemoteFileLocation &remote_location,
+                               const LocalFileLocation &local, int64 size, string name,
+                               const FileEncryptionKey &encryption_key, bool search_file, int8 priority) {
+  if (stop_flag_) {
+    return;
+  }
+  CHECK(query_id_to_node_id_.find(id) == query_id_to_node_id_.end());
+  NodeId node_id = nodes_container_.create(Node());
+  Node *node = nodes_container_.get(node_id);
+  CHECK(node);
+  node->query_id_ = id;
+  auto callback = make_unique<FileDownloaderCallback>(actor_shared(this, node_id));
+  bool is_small = size < 20 * 1024;
+  node->loader_ = create_actor<FileDownloader>("Downloader", remote_location, local, size, std::move(name),
+                                               encryption_key, is_small, search_file, std::move(callback));
+  auto &resource_manager = get_download_resource_manager(is_small, remote_location.get_dc_id());
+  send_closure(resource_manager, &ResourceManager::register_worker,
+               ActorShared<FileLoaderActor>(node->loader_.get(), static_cast<uint64>(-1)), priority);
+  query_id_to_node_id_[id] = node_id;
+}
+
+void FileLoadManager::upload(QueryId id, const LocalFileLocation &local_location,
+                             const RemoteFileLocation &remote_location, int64 size,
+                             const FileEncryptionKey &encryption_key, int8 priority, vector<int> bad_parts) {
+  if (stop_flag_) {
+    return;
+  }
+  CHECK(query_id_to_node_id_.find(id) == query_id_to_node_id_.end());
+  NodeId node_id = nodes_container_.create(Node());
+  Node *node = nodes_container_.get(node_id);
+  CHECK(node);
+  node->query_id_ = id;
+  auto callback = make_unique<FileUploaderCallback>(actor_shared(this, node_id));
+  node->loader_ = create_actor<FileUploader>("Uploader", local_location, remote_location, size, encryption_key,
+                                             std::move(bad_parts), std::move(callback));
+  send_closure(upload_resource_manager_, &ResourceManager::register_worker,
+               ActorShared<FileLoaderActor>(node->loader_.get(), static_cast<uint64>(-1)), priority);
+  query_id_to_node_id_[id] = node_id;
+}
+
+void FileLoadManager::upload_by_hash(QueryId id, const FullLocalFileLocation &local_location, int64 size,
+                                     int8 priority) {
+  if (stop_flag_) {
+    return;
+  }
+  CHECK(query_id_to_node_id_.find(id) == query_id_to_node_id_.end());
+  NodeId node_id = nodes_container_.create(Node());
+  Node *node = nodes_container_.get(node_id);
+  CHECK(node);
+  node->query_id_ = id;
+  auto callback = make_unique<FileHashUploaderCallback>(actor_shared(this, node_id));
+  node->loader_ = create_actor<FileHashUploader>("HashUploader", local_location, size, std::move(callback));
+  send_closure(upload_resource_manager_, &ResourceManager::register_worker,
+               ActorShared<FileLoaderActor>(node->loader_.get(), static_cast<uint64>(-1)), priority);
+  query_id_to_node_id_[id] = node_id;
+}
+
+void FileLoadManager::update_priority(QueryId id, int8 priority) {
+  if (stop_flag_) {
+    return;
+  }
+  auto it = query_id_to_node_id_.find(id);
+  if (it == query_id_to_node_id_.end()) {
+    return;
+  }
+  auto node = nodes_container_.get(it->second);
+  if (node == nullptr) {
+    return;
+  }
+  send_closure(node->loader_, &FileLoaderActor::update_priority, priority);
+}
+
+void FileLoadManager::from_bytes(QueryId id, FileType type, BufferSlice bytes, string name) {
+  if (stop_flag_) {
+    return;
+  }
+  CHECK(query_id_to_node_id_.find(id) == query_id_to_node_id_.end());
+  NodeId node_id = nodes_container_.create(Node());
+  Node *node = nodes_container_.get(node_id);
+  CHECK(node);
+  node->query_id_ = id;
+  auto callback = make_unique<FileFromBytesCallback>(actor_shared(this, node_id));
+  node->loader_ =
+      create_actor<FileFromBytes>("FromBytes", type, std::move(bytes), std::move(name), std::move(callback));
+  query_id_to_node_id_[id] = node_id;
+}
+
+void FileLoadManager::get_content(const FullLocalFileLocation &local_location, Promise<BufferSlice> promise) {
+  // TODO: send query to other thread
+  promise.set_result(read_file(local_location.path_));
+}
+
+// void upload_reload_parts(QueryId id, vector<int32> parts);
+// void upload_restart(QueryId id);
+void FileLoadManager::cancel(QueryId id) {
+  if (stop_flag_) {
+    return;
+  }
+  auto it = query_id_to_node_id_.find(id);
+  if (it == query_id_to_node_id_.end()) {
+    return;
+  }
+  on_error_impl(it->second, Status::Error(1, "Cancelled"));
+}
+void FileLoadManager::update_local_file_location(QueryId id, const LocalFileLocation &local) {
+  if (stop_flag_) {
+    return;
+  }
+  auto it = query_id_to_node_id_.find(id);
+  if (it == query_id_to_node_id_.end()) {
+    return;
+  }
+  auto node = nodes_container_.get(it->second);
+  if (node == nullptr) {
+    return;
+  }
+  send_closure(node->loader_, &FileLoaderActor::update_local_file_location, local);
+}
+void FileLoadManager::close() {
+  nodes_container_.for_each([](auto id, auto &node) { node.loader_.reset(); });
+  stop_flag_ = true;
+  loop();
+}
+
+void FileLoadManager::on_start_download() {
+  auto node_id = get_link_token();
+  auto node = nodes_container_.get(node_id);
+  if (node == nullptr) {
+    return;
+  }
+  if (!stop_flag_) {
+    send_closure(callback_, &Callback::on_start_download, node->query_id_);
+  }
+}
+
+void FileLoadManager::on_partial_download(const PartialLocalFileLocation &partial_local, int64 ready_size) {
+  auto node_id = get_link_token();
+  auto node = nodes_container_.get(node_id);
+  if (node == nullptr) {
+    return;
+  }
+  if (!stop_flag_) {
+    send_closure(callback_, &Callback::on_partial_download, node->query_id_, partial_local, ready_size);
+  }
+}
+
+void FileLoadManager::on_partial_upload(const PartialRemoteFileLocation &partial_remote, int64 ready_size) {
+  auto node_id = get_link_token();
+  auto node = nodes_container_.get(node_id);
+  if (node == nullptr) {
+    return;
+  }
+  if (!stop_flag_) {
+    send_closure(callback_, &Callback::on_partial_upload, node->query_id_, partial_remote, ready_size);
+  }
+}
+
+void FileLoadManager::on_ok_download(const FullLocalFileLocation &local, int64 size) {
+  auto node_id = get_link_token();
+  auto node = nodes_container_.get(node_id);
+  if (node == nullptr) {
+    return;
+  }
+  if (!stop_flag_) {
+    send_closure(callback_, &Callback::on_download_ok, node->query_id_, local, size);
+  }
+  close_node(node_id);
+  loop();
+}
+
+void FileLoadManager::on_ok_upload(FileType file_type, const PartialRemoteFileLocation &remote, int64 size) {
+  auto node_id = get_link_token();
+  auto node = nodes_container_.get(node_id);
+  if (node == nullptr) {
+    return;
+  }
+  if (!stop_flag_) {
+    send_closure(callback_, &Callback::on_upload_ok, node->query_id_, file_type, remote, size);
+  }
+  close_node(node_id);
+  loop();
+}
+
+void FileLoadManager::on_ok_upload_full(const FullRemoteFileLocation &remote) {
+  auto node_id = get_link_token();
+  auto node = nodes_container_.get(node_id);
+  if (node == nullptr) {
+    return;
+  }
+  if (!stop_flag_) {
+    send_closure(callback_, &Callback::on_upload_full_ok, node->query_id_, remote);
+  }
+  close_node(node_id);
+  loop();
+}
+
+void FileLoadManager::on_error(Status status) {
+  auto node_id = get_link_token();
+  on_error_impl(node_id, std::move(status));
+}
+
+void FileLoadManager::on_error_impl(NodeId node_id, Status status) {
+  auto node = nodes_container_.get(node_id);
+  if (node == nullptr) {
+    status.ignore();
+    return;
+  }
+  if (!stop_flag_) {
+    send_closure(callback_, &Callback::on_error, node->query_id_, std::move(status));
+  }
+  close_node(node_id);
+  loop();
+}
+
+void FileLoadManager::hangup_shared() {
+  auto node_id = get_link_token();
+  on_error_impl(node_id, Status::Error(1, "Cancelled"));
+}
+
+void FileLoadManager::loop() {
+  if (stop_flag_) {
+    if (nodes_container_.empty()) {
+      stop();
+    }
+    return;
+  }
+}
+
+void FileLoadManager::close_node(NodeId node_id) {
+  auto node = nodes_container_.get(node_id);
+  CHECK(node);
+  query_id_to_node_id_.erase(node->query_id_);
+  nodes_container_.erase(node_id);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileLoadManager.h b/libs/tdlib/td/td/telegram/files/FileLoadManager.h
new file mode 100644
index 0000000000..d61df5d08e
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileLoadManager.h
@@ -0,0 +1,167 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/files/FileDownloader.h"
+#include "td/telegram/files/FileFromBytes.h"
+#include "td/telegram/files/FileHashUploader.h"
+#include "td/telegram/files/FileLocation.h"
+#include "td/telegram/files/FileUploader.h"
+#include "td/telegram/files/ResourceManager.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/Container.h"
+#include "td/utils/Status.h"
+
+#include <map>
+
+namespace td {
+
+class FileLoadManager final : public Actor {
+ public:
+  using QueryId = uint64;
+  class Callback : public Actor {
+   public:
+    Callback() = default;
+    Callback(const Callback &) = delete;
+    Callback &operator=(const Callback &) = delete;
+    ~Callback() override = default;
+    virtual void on_start_download(QueryId id) = 0;
+    virtual void on_partial_download(QueryId id, const PartialLocalFileLocation &partial_local, int64 ready_size) = 0;
+    virtual void on_partial_upload(QueryId id, const PartialRemoteFileLocation &partial_remote, int64 ready_size) = 0;
+    virtual void on_upload_ok(QueryId id, FileType file_type, const PartialRemoteFileLocation &remtoe, int64 size) = 0;
+    virtual void on_upload_full_ok(QueryId id, const FullRemoteFileLocation &remote) = 0;
+    virtual void on_download_ok(QueryId id, const FullLocalFileLocation &local, int64 size) = 0;
+    virtual void on_error(QueryId id, Status status) = 0;
+  };
+
+  explicit FileLoadManager(ActorShared<Callback> callback, ActorShared<> parent);
+  void download(QueryId id, const FullRemoteFileLocation &remote_location, const LocalFileLocation &local, int64 size,
+                string name, const FileEncryptionKey &encryption_key, bool search_file, int8 priority);
+  void upload(QueryId id, const LocalFileLocation &local_location, const RemoteFileLocation &remote_location,
+              int64 size, const FileEncryptionKey &encryption_key, int8 priority, vector<int> bad_parts);
+  void upload_by_hash(QueryId id, const FullLocalFileLocation &local_location, int64 size, int8 priority);
+  void update_priority(QueryId id, int8 priority);
+  void from_bytes(QueryId id, FileType type, BufferSlice bytes, string name);
+  void cancel(QueryId id);
+  void update_local_file_location(QueryId id, const LocalFileLocation &local);
+  void get_content(const FullLocalFileLocation &local_location, Promise<BufferSlice> promise);
+
+  // just stops actor and all queries. no callbacks will be called
+  void close();
+
+ private:
+  struct Node {
+    QueryId query_id_;
+    ActorOwn<FileLoaderActor> loader_;
+    ResourceState resource_state_;
+  };
+  using NodeId = uint64;
+
+  std::map<DcId, ActorOwn<ResourceManager>> download_resource_manager_map_;
+  std::map<DcId, ActorOwn<ResourceManager>> download_small_resource_manager_map_;
+  ActorOwn<ResourceManager> upload_resource_manager_;
+
+  Container<Node> nodes_container_;
+  ActorShared<Callback> callback_;
+  ActorShared<> parent_;
+  std::map<QueryId, NodeId> query_id_to_node_id_;
+  bool stop_flag_ = false;
+
+  void start_up() override;
+  void loop() override;
+  void hangup_shared() override;
+
+  void close_node(NodeId node_id);
+  ActorOwn<ResourceManager> &get_download_resource_manager(bool is_small, DcId dc_id);
+
+  void on_start_download();
+  void on_partial_download(const PartialLocalFileLocation &partial_local, int64 ready_size);
+  void on_partial_upload(const PartialRemoteFileLocation &partial_remote, int64 ready_size);
+  void on_ok_download(const FullLocalFileLocation &local, int64 size);
+  void on_ok_upload(FileType file_type, const PartialRemoteFileLocation &remote, int64 size);
+  void on_ok_upload_full(const FullRemoteFileLocation &remote);
+  void on_error(Status status);
+  void on_error_impl(NodeId node_id, Status status);
+
+  class FileDownloaderCallback : public FileDownloader::Callback {
+   public:
+    explicit FileDownloaderCallback(ActorShared<FileLoadManager> actor_id) : actor_id_(std::move(actor_id)) {
+    }
+
+   private:
+    ActorShared<FileLoadManager> actor_id_;
+
+    void on_start_download() override {
+      send_closure(actor_id_, &FileLoadManager::on_start_download);
+    }
+    void on_partial_download(const PartialLocalFileLocation &partial_local, int64 ready_size) override {
+      send_closure(actor_id_, &FileLoadManager::on_partial_download, partial_local, ready_size);
+    }
+    void on_ok(const FullLocalFileLocation &full_local, int64 size) override {
+      send_closure(std::move(actor_id_), &FileLoadManager::on_ok_download, full_local, size);
+    }
+    void on_error(Status status) override {
+      send_closure(std::move(actor_id_), &FileLoadManager::on_error, std::move(status));
+    }
+  };
+
+  class FileUploaderCallback : public FileUploader::Callback {
+   public:
+    explicit FileUploaderCallback(ActorShared<FileLoadManager> actor_id) : actor_id_(std::move(actor_id)) {
+    }
+
+   private:
+    ActorShared<FileLoadManager> actor_id_;
+
+    void on_partial_upload(const PartialRemoteFileLocation &partial_remote, int64 ready_size) override {
+      send_closure(actor_id_, &FileLoadManager::on_partial_upload, partial_remote, ready_size);
+    }
+    void on_ok(FileType file_type, const PartialRemoteFileLocation &partial_remote, int64 size) override {
+      send_closure(std::move(actor_id_), &FileLoadManager::on_ok_upload, file_type, partial_remote, size);
+    }
+    void on_error(Status status) override {
+      send_closure(std::move(actor_id_), &FileLoadManager::on_error, std::move(status));
+    }
+  };
+  class FileHashUploaderCallback : public FileHashUploader::Callback {
+   public:
+    explicit FileHashUploaderCallback(ActorShared<FileLoadManager> actor_id) : actor_id_(std::move(actor_id)) {
+    }
+
+   private:
+    ActorShared<FileLoadManager> actor_id_;
+
+    void on_ok(const FullRemoteFileLocation &remote) override {
+      send_closure(std::move(actor_id_), &FileLoadManager::on_ok_upload_full, remote);
+    }
+    void on_error(Status status) override {
+      send_closure(std::move(actor_id_), &FileLoadManager::on_error, std::move(status));
+    }
+  };
+
+  class FileFromBytesCallback : public FileFromBytes::Callback {
+   public:
+    explicit FileFromBytesCallback(ActorShared<FileLoadManager> actor_id) : actor_id_(std::move(actor_id)) {
+    }
+
+   private:
+    ActorShared<FileLoadManager> actor_id_;
+
+    void on_ok(const FullLocalFileLocation &full_local, int64 size) override {
+      send_closure(std::move(actor_id_), &FileLoadManager::on_ok_download, full_local, size);
+    }
+    void on_error(Status status) override {
+      send_closure(std::move(actor_id_), &FileLoadManager::on_error, std::move(status));
+    }
+  };
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileLoader.cpp b/libs/tdlib/td/td/telegram/files/FileLoader.cpp
new file mode 100644
index 0000000000..8431aa8553
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileLoader.cpp
@@ -0,0 +1,292 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/files/FileLoader.h"
+
+#include "td/telegram/files/ResourceManager.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+#include "td/telegram/Td.h"
+#include "td/telegram/UniqueId.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/ScopeGuard.h"
+
+#include <tuple>
+
+namespace td {
+void FileLoader::set_resource_manager(ActorShared<ResourceManager> resource_manager) {
+  resource_manager_ = std::move(resource_manager);
+  send_closure(resource_manager_, &ResourceManager::update_resources, resource_state_);
+}
+void FileLoader::update_priority(int8 priority) {
+  send_closure(resource_manager_, &ResourceManager::update_priority, priority);
+}
+void FileLoader::update_resources(const ResourceState &other) {
+  resource_state_.update_slave(other);
+  VLOG(files) << "update resources " << resource_state_;
+  loop();
+}
+void FileLoader::set_ordered_flag(bool flag) {
+  ordered_flag_ = flag;
+}
+size_t FileLoader::get_part_size() const {
+  return parts_manager_.get_part_size();
+}
+void FileLoader::hangup() {
+  // if (!stop_flag_) {
+  // stop_flag_ = true;
+  // on_error(Status::Error("Cancelled"));
+  //}
+  stop();
+}
+
+void FileLoader::update_local_file_location(const LocalFileLocation &local) {
+  auto r_prefix_info = on_update_local_location(local);
+  if (r_prefix_info.is_error()) {
+    on_error(r_prefix_info.move_as_error());
+    stop_flag_ = true;
+    return;
+  }
+  auto prefix_info = r_prefix_info.move_as_ok();
+  auto status = parts_manager_.set_known_prefix(narrow_cast<size_t>(prefix_info.size), prefix_info.is_ready);
+  if (status.is_error()) {
+    on_error(std::move(status));
+    stop_flag_ = true;
+    return;
+  }
+  loop();
+}
+
+void FileLoader::start_up() {
+  auto r_file_info = init();
+  if (r_file_info.is_error()) {
+    on_error(r_file_info.move_as_error());
+    stop_flag_ = true;
+    return;
+  }
+  auto file_info = r_file_info.ok();
+  auto size = file_info.size;
+  auto expected_size = max(size, file_info.expected_size);
+  bool is_size_final = file_info.is_size_final;
+  auto part_size = file_info.part_size;
+  auto &ready_parts = file_info.ready_parts;
+  auto use_part_count_limit = file_info.use_part_count_limit;
+  auto status = parts_manager_.init(size, expected_size, is_size_final, part_size, ready_parts, use_part_count_limit);
+  if (file_info.only_check) {
+    parts_manager_.set_checked_prefix_size(0);
+  }
+  if (status.is_error()) {
+    on_error(std::move(status));
+    stop_flag_ = true;
+    return;
+  }
+  if (ordered_flag_) {
+    ordered_parts_ = OrderedEventsProcessor<std::pair<Part, NetQueryPtr>>(parts_manager_.get_ready_prefix_count());
+  }
+  if (file_info.need_delay) {
+    delay_dispatcher_ = create_actor<DelayDispatcher>("DelayDispatcher", 0.003);
+    next_delay_ = 0.05;
+  }
+  resource_state_.set_unit_size(parts_manager_.get_part_size());
+  update_estimated_limit();
+  on_progress_impl(narrow_cast<size_t>(parts_manager_.get_ready_size()));
+  yield();
+}
+
+void FileLoader::loop() {
+  if (stop_flag_) {
+    return;
+  }
+  auto status = do_loop();
+  if (status.is_error()) {
+    if (status.code() == 1) {
+      return;
+    }
+    on_error(std::move(status));
+    stop_flag_ = true;
+    return;
+  }
+}
+Status FileLoader::do_loop() {
+  TRY_RESULT(check_info,
+             check_loop(parts_manager_.get_checked_prefix_size(), parts_manager_.get_unchecked_ready_prefix_size(),
+                        parts_manager_.unchecked_ready()));
+  if (check_info.changed) {
+    on_progress_impl(narrow_cast<size_t>(parts_manager_.get_ready_size()));
+  }
+  for (auto &query : check_info.queries) {
+    G()->net_query_dispatcher().dispatch_with_callback(
+        std::move(query), actor_shared(this, UniqueId::next(UniqueId::Type::Default, CommonQueryKey)));
+  }
+  if (check_info.need_check) {
+    parts_manager_.set_need_check();
+    parts_manager_.set_checked_prefix_size(check_info.checked_prefix_size);
+  }
+
+  if (parts_manager_.ready()) {
+    TRY_STATUS(parts_manager_.finish());
+    TRY_STATUS(on_ok(parts_manager_.get_size()));
+    LOG(INFO) << "Bad download order rate: "
+              << (debug_total_parts_ == 0 ? 0.0 : 100.0 * debug_bad_part_order_ / debug_total_parts_) << "% "
+              << debug_bad_part_order_ << "/" << debug_total_parts_ << " " << format::as_array(debug_bad_parts_);
+    stop_flag_ = true;
+    return Status::OK();
+  }
+
+  TRY_STATUS(before_start_parts());
+  SCOPE_EXIT {
+    after_start_parts();
+  };
+  while (true) {
+    if (blocking_id_ != 0) {
+      break;
+    }
+    if (resource_state_.unused() < static_cast<int64>(parts_manager_.get_part_size())) {
+      VLOG(files) << "Got only " << resource_state_.unused() << " resource";
+      break;
+    }
+    TRY_RESULT(part, parts_manager_.start_part());
+    if (part.size == 0) {
+      break;
+    }
+    VLOG(files) << "Start part " << tag("id", part.id) << tag("size", part.size);
+    resource_state_.start_use(static_cast<int64>(part.size));
+
+    TRY_RESULT(query_flag, start_part(part, parts_manager_.get_part_count()));
+    NetQueryPtr query;
+    bool is_blocking;
+    std::tie(query, is_blocking) = std::move(query_flag);
+    uint64 id = UniqueId::next();
+    if (is_blocking) {
+      CHECK(blocking_id_ == 0);
+      blocking_id_ = id;
+    }
+    part_map_[id] = std::make_pair(part, query->cancel_slot_.get_signal_new());
+    // part_map_[id] = std::make_pair(part, query.get_weak());
+
+    auto callback = actor_shared(this, id);
+    if (delay_dispatcher_.empty()) {
+      G()->net_query_dispatcher().dispatch_with_callback(std::move(query), std::move(callback));
+    } else {
+      send_closure(delay_dispatcher_, &DelayDispatcher::send_with_callback_and_delay, std::move(query),
+                   std::move(callback), next_delay_);
+      next_delay_ = std::max(next_delay_ * 0.8, 0.003);
+    }
+  }
+  return Status::OK();
+}
+
+void FileLoader::tear_down() {
+  for (auto &it : part_map_) {
+    it.second.second.reset();  // cancel_query(it.second.second);
+  }
+}
+void FileLoader::update_estimated_limit() {
+  if (stop_flag_) {
+    return;
+  }
+  auto estimated_exta = parts_manager_.get_expected_size() - parts_manager_.get_ready_size();
+  resource_state_.update_estimated_limit(estimated_exta);
+  VLOG(files) << "update estimated limit " << estimated_exta;
+  if (!resource_manager_.empty()) {
+    keep_fd_flag(narrow_cast<uint64>(resource_state_.active_limit()) >= parts_manager_.get_part_size());
+    send_closure(resource_manager_, &ResourceManager::update_resources, resource_state_);
+  }
+}
+
+void FileLoader::on_result(NetQueryPtr query) {
+  if (stop_flag_) {
+    return;
+  }
+  auto id = get_link_token();
+  if (id == blocking_id_) {
+    blocking_id_ = 0;
+  }
+  if (UniqueId::extract_key(id) == CommonQueryKey) {
+    on_common_query(std::move(query));
+    return loop();
+  }
+  auto it = part_map_.find(id);
+  if (it == part_map_.end()) {
+    LOG(WARNING) << "Got result for unknown part";
+    return;
+  }
+
+  Part part = it->second.first;
+  it->second.second.release();
+  CHECK(query->is_ready());
+
+  bool next = false;
+  auto status = [&] {
+    TRY_RESULT(should_restart, should_restart_part(part, query));
+    if (should_restart) {
+      VLOG(files) << "Restart part " << tag("id", part.id) << tag("size", part.size);
+      resource_state_.stop_use(static_cast<int64>(part.size));
+      parts_manager_.on_part_failed(part.id);
+    } else {
+      next = true;
+    }
+    return Status::OK();
+  }();
+  if (status.is_error()) {
+    on_error(std::move(status));
+    stop_flag_ = true;
+    return;
+  }
+
+  if (next) {
+    if (ordered_flag_) {
+      auto seq_no = part.id;
+      ordered_parts_.add(seq_no, std::make_pair(part, std::move(query)),
+                         [this](auto seq_no, auto &&p) { this->on_part_query(p.first, std::move(p.second)); });
+    } else {
+      on_part_query(part, std::move(query));
+    }
+  }
+  update_estimated_limit();
+  loop();
+}
+
+void FileLoader::on_part_query(Part part, NetQueryPtr query) {
+  auto status = try_on_part_query(part, std::move(query));
+  if (status.is_error()) {
+    on_error(std::move(status));
+    stop_flag_ = true;
+  }
+}
+
+void FileLoader::on_common_query(NetQueryPtr query) {
+  auto status = process_check_query(std::move(query));
+  if (status.is_error()) {
+    on_error(std::move(status));
+    stop_flag_ = true;
+  }
+}
+
+Status FileLoader::try_on_part_query(Part part, NetQueryPtr query) {
+  TRY_RESULT(size, process_part(part, std::move(query)));
+  VLOG(files) << "Ok part " << tag("id", part.id) << tag("size", part.size);
+  resource_state_.stop_use(static_cast<int64>(part.size));
+  auto old_ready_prefix_count = parts_manager_.get_ready_prefix_count();
+  TRY_STATUS(parts_manager_.on_part_ok(part.id, part.size, size));
+  auto new_ready_prefix_count = parts_manager_.get_ready_prefix_count();
+  debug_total_parts_++;
+  if (old_ready_prefix_count == new_ready_prefix_count) {
+    debug_bad_parts_.push_back(part.id);
+    debug_bad_part_order_++;
+  }
+  on_progress_impl(size);
+  return Status::OK();
+}
+
+void FileLoader::on_progress_impl(size_t size) {
+  on_progress(parts_manager_.get_part_count(), static_cast<int32>(parts_manager_.get_part_size()),
+              parts_manager_.get_ready_prefix_count(), parts_manager_.ready(), parts_manager_.get_ready_size());
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileLoader.h b/libs/tdlib/td/td/telegram/files/FileLoader.h
new file mode 100644
index 0000000000..a97a5199e9
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileLoader.h
@@ -0,0 +1,129 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/files/FileLoaderActor.h"
+#include "td/telegram/files/FileLocation.h"
+#include "td/telegram/files/PartsManager.h"
+#include "td/telegram/files/ResourceManager.h"
+#include "td/telegram/files/ResourceState.h"
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/telegram/DelayDispatcher.h"
+
+#include "td/utils/OrderedEventsProcessor.h"
+#include "td/utils/Status.h"
+
+#include <map>
+#include <utility>
+
+namespace td {
+class FileLoader : public FileLoaderActor {
+ public:
+  class Callback {
+   public:
+    Callback() = default;
+    Callback(const Callback &) = delete;
+    Callback &operator=(const Callback &) = delete;
+    virtual ~Callback() = default;
+  };
+  void set_resource_manager(ActorShared<ResourceManager> resource_manager) override;
+  void update_priority(int8 priority) override;
+  void update_resources(const ResourceState &other) override;
+
+  void update_local_file_location(const LocalFileLocation &local) override;
+
+ protected:
+  void set_ordered_flag(bool flag);
+  size_t get_part_size() const;
+
+  struct PrefixInfo {
+    int64 size = -1;
+    bool is_ready = false;
+  };
+  struct FileInfo {
+    int64 size;
+    int64 expected_size = 0;
+    bool is_size_final;
+    int32 part_size;
+    std::vector<int> ready_parts;
+    bool use_part_count_limit = true;
+    bool only_check = false;
+    bool need_delay = false;
+  };
+  virtual Result<FileInfo> init() TD_WARN_UNUSED_RESULT = 0;
+  virtual Status on_ok(int64 size) TD_WARN_UNUSED_RESULT = 0;
+  virtual void on_error(Status status) = 0;
+  virtual Status before_start_parts() {
+    return Status::OK();
+  }
+  virtual Result<std::pair<NetQueryPtr, bool>> start_part(Part part, int part_count) TD_WARN_UNUSED_RESULT = 0;
+  virtual void after_start_parts() {
+  }
+  virtual Result<size_t> process_part(Part part, NetQueryPtr net_query) TD_WARN_UNUSED_RESULT = 0;
+  virtual void on_progress(int32 part_count, int32 part_size, int32 ready_part_count, bool is_ready,
+                           int64 ready_size) = 0;
+  virtual Callback *get_callback() = 0;
+  virtual Result<PrefixInfo> on_update_local_location(const LocalFileLocation &location) TD_WARN_UNUSED_RESULT {
+    return Status::Error("unsupported");
+  }
+  virtual Result<bool> should_restart_part(Part part, NetQueryPtr &net_query) TD_WARN_UNUSED_RESULT {
+    return false;
+  }
+
+  virtual Status process_check_query(NetQueryPtr net_query) {
+    return Status::Error("unsupported");
+  }
+  struct CheckInfo {
+    bool need_check{false};
+    bool changed{false};
+    int64 checked_prefix_size{0};
+    std::vector<NetQueryPtr> queries;
+  };
+  virtual Result<CheckInfo> check_loop(int64 checked_prefix_size, int64 ready_prefix_size, bool is_ready) {
+    return CheckInfo{};
+  }
+
+  virtual void keep_fd_flag(bool keep_fd) {
+  }
+
+ private:
+  enum { CommonQueryKey = 2 };
+  bool stop_flag_ = false;
+  ActorShared<ResourceManager> resource_manager_;
+  ResourceState resource_state_;
+  PartsManager parts_manager_;
+  uint64 blocking_id_{0};
+  std::map<uint64, std::pair<Part, ActorShared<>>> part_map_;
+  // std::map<uint64, std::pair<Part, NetQueryRef>> part_map_;
+  bool ordered_flag_ = false;
+  OrderedEventsProcessor<std::pair<Part, NetQueryPtr>> ordered_parts_;
+  ActorOwn<DelayDispatcher> delay_dispatcher_;
+  double next_delay_ = 0;
+
+  uint32 debug_total_parts_ = 0;
+  uint32 debug_bad_part_order_ = 0;
+  std::vector<int32> debug_bad_parts_;
+
+  void start_up() override;
+  void loop() override;
+  Status do_loop();
+  void hangup() override;
+  void tear_down() override;
+
+  void update_estimated_limit();
+  void on_progress_impl(size_t size);
+
+  void on_result(NetQueryPtr query) override;
+  void on_part_query(Part part, NetQueryPtr query);
+  void on_common_query(NetQueryPtr query);
+  Status try_on_part_query(Part part, NetQueryPtr query);
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileLoaderActor.h b/libs/tdlib/td/td/telegram/files/FileLoaderActor.h
new file mode 100644
index 0000000000..d802f589ca
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileLoaderActor.h
@@ -0,0 +1,28 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/files/ResourceState.h"
+#include "td/telegram/net/NetQuery.h"
+
+namespace td {
+
+class LocalFileLocation;
+class ResourceManager;
+
+class FileLoaderActor : public NetQueryCallback {
+ public:
+  virtual void set_resource_manager(ActorShared<ResourceManager>) = 0;
+  virtual void update_priority(int8 priority) = 0;
+  virtual void update_resources(const ResourceState &other) = 0;
+
+  // TODO: existence of this function is a dirty hack. Refactoring is highly appreciated
+  virtual void update_local_file_location(const LocalFileLocation &local) {
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileLoaderUtils.cpp b/libs/tdlib/td/td/telegram/files/FileLoaderUtils.cpp
new file mode 100644
index 0000000000..1e89cb72ee
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileLoaderUtils.cpp
@@ -0,0 +1,168 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/files/FileLoaderUtils.h"
+
+#include "td/telegram/files/FileLocation.h"
+#include "td/telegram/Global.h"
+
+#include "td/utils/common.h"
+#include "td/utils/filesystem.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/PathView.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/port/path.h"
+#include "td/utils/Random.h"
+#include "td/utils/StringBuilder.h"
+
+#include <tuple>
+
+namespace td {
+
+namespace {
+Result<std::pair<FileFd, string>> try_create_new_file(Result<CSlice> result_name) {
+  TRY_RESULT(name, std::move(result_name));
+  TRY_RESULT(fd, FileFd::open(name, FileFd::Read | FileFd::Write | FileFd::CreateNew, 0640));
+  return std::make_pair(std::move(fd), name.str());
+}
+Result<std::pair<FileFd, string>> try_open_file(Result<CSlice> result_name) {
+  TRY_RESULT(name, std::move(result_name));
+  TRY_RESULT(fd, FileFd::open(name, FileFd::Read, 0640));
+  return std::make_pair(std::move(fd), name.str());
+}
+
+struct RandSuff {
+  int len;
+};
+StringBuilder &operator<<(StringBuilder &sb, const RandSuff &) {
+  for (int i = 0; i < 6; i++) {
+    sb << format::hex_digit(Random::fast(0, 15));
+  }
+  return sb;
+}
+struct Ext {
+  Slice ext;
+};
+StringBuilder &operator<<(StringBuilder &sb, const Ext &ext) {
+  if (ext.ext.empty()) {
+    return sb;
+  }
+  return sb << "." << ext.ext;
+}
+}  // namespace
+
+Result<std::pair<FileFd, string>> open_temp_file(const FileType &file_type) {
+  auto pmc = G()->td_db()->get_binlog_pmc();
+  // TODO: CAS?
+  int32 file_id = to_integer<int32>(pmc->get("tmp_file_id"));
+  pmc->set("tmp_file_id", to_string(file_id + 1));
+
+  auto temp_dir = get_files_temp_dir(file_type);
+  auto res = try_create_new_file(PSLICE_SAFE() << temp_dir << file_id);
+  if (res.is_error()) {
+    res = try_create_new_file(PSLICE_SAFE() << temp_dir << file_id << "_" << RandSuff{6});
+  }
+  return res;
+}
+
+template <class F>
+bool for_suggested_file_name(CSlice name, bool use_pmc, bool use_random, F &&callback) {
+  auto try_callback = [&](Result<CSlice> r_path) {
+    if (r_path.is_error()) {
+      return true;
+    }
+    return callback(r_path.move_as_ok());
+  };
+  auto cleaned_name = clean_filename(name);
+  PathView path_view(cleaned_name);
+  auto stem = path_view.file_stem();
+  auto ext = path_view.extension();
+  bool active = true;
+  if (!stem.empty() && !G()->parameters().ignore_file_names) {
+    active = try_callback(PSLICE_SAFE() << stem << Ext{ext});
+    for (int i = 0; active && i < 10; i++) {
+      active = try_callback(PSLICE_SAFE() << stem << "_(" << i << ")" << Ext{ext});
+    }
+    for (int i = 2; active && i < 12 && use_random; i++) {
+      active = try_callback(PSLICE_SAFE() << stem << "_(" << RandSuff{i} << ")" << Ext{ext});
+    }
+  } else if (use_pmc) {
+    auto pmc = G()->td_db()->get_binlog_pmc();
+    int32 file_id = to_integer<int32>(pmc->get("perm_file_id"));
+    pmc->set("perm_file_id", to_string(file_id + 1));
+    active = try_callback(PSLICE_SAFE() << "file_" << file_id << Ext{ext});
+    if (active) {
+      active = try_callback(PSLICE_SAFE() << "file_" << file_id << "_" << RandSuff{6} << Ext{ext});
+    }
+  }
+  return active;
+}
+
+Result<string> create_from_temp(CSlice temp_path, CSlice dir, CSlice name) {
+  LOG(INFO) << "Create file in directory " << dir << " with suggested name " << name << " from temporary file "
+            << temp_path;
+  Result<std::pair<FileFd, string>> res = Status::Error(500, "Can't find suitable file name");
+  for_suggested_file_name(name, true, true, [&](CSlice suggested_name) {
+    res = try_create_new_file(PSLICE_SAFE() << dir << suggested_name);
+    return res.is_error();
+  });
+  TRY_RESULT(tmp, std::move(res));
+  tmp.first.close();
+  auto perm_path = std::move(tmp.second);
+  TRY_STATUS(rename(temp_path, perm_path));
+  return perm_path;
+}
+
+Result<string> search_file(CSlice dir, CSlice name, int64 expected_size) {
+  Result<std::string> res = Status::Error(500, "Can't find suitable file name");
+  for_suggested_file_name(name, false, false, [&](CSlice suggested_name) {
+    auto r_pair = try_open_file(PSLICE_SAFE() << dir << suggested_name);
+    if (r_pair.is_error()) {
+      return false;
+    }
+    FileFd fd;
+    std::string path;
+    std::tie(fd, path) = r_pair.move_as_ok();
+    if (fd.stat().size_ != expected_size) {
+      return true;
+    }
+    fd.close();
+    res = std::move(path);
+    return false;
+  });
+  return res;
+}
+
+const char *file_type_name[file_type_size] = {"thumbnails", "profile_photos", "photos",     "voice",
+                                              "videos",     "documents",      "secret",     "temp",
+                                              "stickers",   "music",          "animations", "secret_thumbnails",
+                                              "wallpapers", "video_notes"};
+
+string get_file_base_dir(const FileDirType &file_dir_type) {
+  switch (file_dir_type) {
+    case FileDirType::Secure:
+      return G()->get_dir().str();
+    case FileDirType::Common:
+      return G()->get_files_dir().str();
+    default:
+      UNREACHABLE();
+      return "";
+  }
+}
+
+string get_files_base_dir(const FileType &file_type) {
+  return get_file_base_dir(get_file_dir_type(file_type));
+}
+string get_files_temp_dir(const FileType &file_type) {
+  return get_files_base_dir(file_type) + "temp" + TD_DIR_SLASH;
+}
+string get_files_dir(const FileType &file_type) {
+  return get_files_base_dir(file_type) + file_type_name[static_cast<int32>(file_type)] + TD_DIR_SLASH;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileLoaderUtils.h b/libs/tdlib/td/td/telegram/files/FileLoaderUtils.h
new file mode 100644
index 0000000000..7eaf1e12e8
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileLoaderUtils.h
@@ -0,0 +1,25 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <utility>
+
+namespace td {
+enum class FileType : int8;
+
+Result<std::pair<FileFd, string>> open_temp_file(const FileType &file_type) TD_WARN_UNUSED_RESULT;
+Result<string> create_from_temp(CSlice temp_path, CSlice dir, CSlice name) TD_WARN_UNUSED_RESULT;
+Result<string> search_file(CSlice dir, CSlice name, int64 expected_size) TD_WARN_UNUSED_RESULT;
+string get_files_base_dir(const FileType &file_type);
+string get_files_temp_dir(const FileType &file_type);
+string get_files_dir(const FileType &file_type);
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileLocation.h b/libs/tdlib/td/td/telegram/files/FileLocation.h
new file mode 100644
index 0000000000..7733b65d2a
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileLocation.h
@@ -0,0 +1,1199 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/DialogId.h"
+#include "td/telegram/net/DcId.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/crypto.h"
+#include "td/utils/format.h"
+#include "td/utils/int_types.h"
+#include "td/utils/logging.h"
+#include "td/utils/Random.h"
+#include "td/utils/Slice.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tl_helpers.h"
+#include "td/utils/tl_storers.h"
+#include "td/utils/Variant.h"
+
+#include <cstring>
+#include <tuple>
+
+namespace td {
+
+enum class FileType : int8 {
+  Thumbnail,
+  ProfilePhoto,
+  Photo,
+  VoiceNote,
+  Video,
+  Document,
+  Encrypted,
+  Temp,
+  Sticker,
+  Audio,
+  Animation,
+  EncryptedThumbnail,
+  Wallpaper,
+  VideoNote,
+  Size,
+  None
+};
+
+inline FileType from_td_api(const td_api::FileType &file_type) {
+  switch (file_type.get_id()) {
+    case td_api::fileTypeThumbnail::ID:
+      return FileType::Thumbnail;
+    case td_api::fileTypeProfilePhoto::ID:
+      return FileType::ProfilePhoto;
+    case td_api::fileTypePhoto::ID:
+      return FileType::Photo;
+    case td_api::fileTypeVoiceNote::ID:
+      return FileType::VoiceNote;
+    case td_api::fileTypeVideo::ID:
+      return FileType::Video;
+    case td_api::fileTypeDocument::ID:
+      return FileType::Document;
+    case td_api::fileTypeSecret::ID:
+      return FileType::Encrypted;
+    case td_api::fileTypeUnknown::ID:
+      return FileType::Temp;
+    case td_api::fileTypeSticker::ID:
+      return FileType::Sticker;
+    case td_api::fileTypeAudio::ID:
+      return FileType::Audio;
+    case td_api::fileTypeAnimation::ID:
+      return FileType::Animation;
+    case td_api::fileTypeSecretThumbnail::ID:
+      return FileType::EncryptedThumbnail;
+    case td_api::fileTypeWallpaper::ID:
+      return FileType::Wallpaper;
+    case td_api::fileTypeVideoNote::ID:
+      return FileType::VideoNote;
+    case td_api::fileTypeNone::ID:
+      return FileType::None;
+    default:
+      UNREACHABLE();
+      return FileType::None;
+  }
+}
+
+inline tl_object_ptr<td_api::FileType> as_td_api(FileType file_type) {
+  switch (file_type) {
+    case FileType::Thumbnail:
+      return make_tl_object<td_api::fileTypeThumbnail>();
+    case FileType::ProfilePhoto:
+      return make_tl_object<td_api::fileTypeProfilePhoto>();
+    case FileType::Photo:
+      return make_tl_object<td_api::fileTypePhoto>();
+    case FileType::VoiceNote:
+      return make_tl_object<td_api::fileTypeVoiceNote>();
+    case FileType::Video:
+      return make_tl_object<td_api::fileTypeVideo>();
+    case FileType::Document:
+      return make_tl_object<td_api::fileTypeDocument>();
+    case FileType::Encrypted:
+      return make_tl_object<td_api::fileTypeSecret>();
+    case FileType::Temp:
+      return make_tl_object<td_api::fileTypeUnknown>();
+    case FileType::Sticker:
+      return make_tl_object<td_api::fileTypeSticker>();
+    case FileType::Audio:
+      return make_tl_object<td_api::fileTypeAudio>();
+    case FileType::Animation:
+      return make_tl_object<td_api::fileTypeAnimation>();
+    case FileType::EncryptedThumbnail:
+      return make_tl_object<td_api::fileTypeSecretThumbnail>();
+    case FileType::Wallpaper:
+      return make_tl_object<td_api::fileTypeWallpaper>();
+    case FileType::VideoNote:
+      return make_tl_object<td_api::fileTypeVideoNote>();
+    case FileType::None:
+      return make_tl_object<td_api::fileTypeNone>();
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+enum class FileDirType : int8 { Secure, Common };
+inline FileDirType get_file_dir_type(FileType file_type) {
+  switch (file_type) {
+    case FileType::Thumbnail:
+    case FileType::ProfilePhoto:
+    case FileType::Encrypted:
+    case FileType::Sticker:
+    case FileType::Temp:
+    case FileType::Wallpaper:
+    case FileType::EncryptedThumbnail:
+      return FileDirType::Secure;
+    default:
+      return FileDirType::Common;
+  }
+}
+
+constexpr int32 file_type_size = static_cast<int32>(FileType::Size);
+extern const char *file_type_name[file_type_size];
+
+struct FileEncryptionKey {
+  FileEncryptionKey() = default;
+  FileEncryptionKey(Slice key, Slice iv) : key_iv_(key.size() + iv.size(), '\0') {
+    if (key.size() != 32 || iv.size() != 32) {
+      LOG(ERROR) << "Wrong key/iv sizes: " << key.size() << " " << iv.size();
+      return;
+    }
+    CHECK(key_iv_.size() == 64);
+    std::memcpy(&key_iv_[0], key.data(), key.size());
+    std::memcpy(&key_iv_[key.size()], iv.data(), iv.size());
+  }
+  static FileEncryptionKey create() {
+    FileEncryptionKey res;
+    res.key_iv_.resize(64);
+    Random::secure_bytes(res.key_iv_);
+    return res;
+  }
+
+  const UInt256 &key() const {
+    CHECK(key_iv_.size() == 64);
+    return *reinterpret_cast<const UInt256 *>(key_iv_.data());
+  }
+  Slice key_slice() const {
+    CHECK(key_iv_.size() == 64);
+    return Slice(key_iv_.data(), 32);
+  }
+
+  UInt256 &mutable_iv() {
+    CHECK(key_iv_.size() == 64);
+    return *reinterpret_cast<UInt256 *>(&key_iv_[0] + 32);
+  }
+  Slice iv_slice() const {
+    CHECK(key_iv_.size() == 64);
+    return Slice(key_iv_.data() + 32, 32);
+  }
+
+  int32 calc_fingerprint() const {
+    char buf[16];
+    md5(key_iv_, {buf, sizeof(buf)});
+    return as<int32>(buf) ^ as<int32>(buf + 4);
+  }
+
+  bool empty() const {
+    return key_iv_.empty();
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(key_iv_, storer);
+  }
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(key_iv_, parser);
+  }
+
+  string key_iv_;  // TODO wrong alignment is possible
+};
+
+inline bool operator==(const FileEncryptionKey &lhs, const FileEncryptionKey &rhs) {
+  return lhs.key_iv_ == rhs.key_iv_;
+}
+
+inline bool operator!=(const FileEncryptionKey &lhs, const FileEncryptionKey &rhs) {
+  return !(lhs == rhs);
+}
+
+struct EmptyRemoteFileLocation {
+  template <class StorerT>
+  void store(StorerT &storer) const {
+  }
+  template <class ParserT>
+  void parse(ParserT &parser) {
+  }
+};
+
+inline bool operator==(const EmptyRemoteFileLocation &lhs, const EmptyRemoteFileLocation &rhs) {
+  return true;
+}
+
+inline bool operator!=(const EmptyRemoteFileLocation &lhs, const EmptyRemoteFileLocation &rhs) {
+  return !(lhs == rhs);
+}
+
+struct PartialRemoteFileLocation {
+  int64 file_id_;
+  int32 part_count_;
+  int32 part_size_;
+  int32 ready_part_count_;
+  int32 is_big_;
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    using td::store;
+    store(file_id_, storer);
+    store(part_count_, storer);
+    store(part_size_, storer);
+    store(ready_part_count_, storer);
+    store(is_big_, storer);
+  }
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    using td::parse;
+    parse(file_id_, parser);
+    parse(part_count_, parser);
+    parse(part_size_, parser);
+    parse(ready_part_count_, parser);
+    parse(is_big_, parser);
+  }
+};
+
+inline bool operator==(const PartialRemoteFileLocation &lhs, const PartialRemoteFileLocation &rhs) {
+  return lhs.file_id_ == rhs.file_id_ && lhs.part_count_ == rhs.part_count_ && lhs.part_size_ == rhs.part_size_ &&
+         lhs.ready_part_count_ == rhs.ready_part_count_ && lhs.is_big_ == rhs.is_big_;
+}
+
+inline bool operator!=(const PartialRemoteFileLocation &lhs, const PartialRemoteFileLocation &rhs) {
+  return !(lhs == rhs);
+}
+
+struct PhotoRemoteFileLocation {
+  int64 id_;
+  int64 access_hash_;
+  int64 volume_id_;
+  int64 secret_;
+  int32 local_id_;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    using td::store;
+    store(id_, storer);
+    store(access_hash_, storer);
+    store(volume_id_, storer);
+    store(secret_, storer);
+    store(local_id_, storer);
+  }
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    using td::parse;
+    parse(id_, parser);
+    parse(access_hash_, parser);
+    parse(volume_id_, parser);
+    parse(secret_, parser);
+    parse(local_id_, parser);
+  }
+  struct AsKey {
+    const PhotoRemoteFileLocation &key;
+    template <class StorerT>
+    void store(StorerT &storer) const {
+      using td::store;
+      store(key.id_, storer);
+      store(key.volume_id_, storer);
+      store(key.local_id_, storer);
+    }
+  };
+  AsKey as_key() const {
+    return AsKey{*this};
+  }
+
+  bool operator<(const PhotoRemoteFileLocation &other) const {
+    return std::tie(id_, volume_id_, local_id_) < std::tie(other.id_, other.volume_id_, other.local_id_);
+  }
+  bool operator==(const PhotoRemoteFileLocation &other) const {
+    return std::tie(id_, volume_id_, local_id_) == std::tie(other.id_, other.volume_id_, other.local_id_);
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &string_builder, const PhotoRemoteFileLocation &location) {
+  return string_builder << "[id = " << location.id_ << ", access_hash = " << location.access_hash_
+                        << ", volume_id = " << location.volume_id_ << ", secret = " << location.secret_
+                        << ", local_id = " << location.local_id_ << "]";
+}
+
+struct WebRemoteFileLocation {
+  string url_;
+  int64 access_hash_;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    using td::store;
+    store(url_, storer);
+    store(access_hash_, storer);
+  }
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    using td::parse;
+    parse(url_, parser);
+    parse(access_hash_, parser);
+  }
+  struct AsKey {
+    const WebRemoteFileLocation &key;
+    template <class StorerT>
+    void store(StorerT &storer) const {
+      using td::store;
+      store(key.url_, storer);
+    }
+  };
+  AsKey as_key() const {
+    return AsKey{*this};
+  }
+  bool operator<(const WebRemoteFileLocation &other) const {
+    return url_ < other.url_;
+  }
+  bool operator==(const WebRemoteFileLocation &other) const {
+    return url_ == other.url_;
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &string_builder, const WebRemoteFileLocation &location) {
+  return string_builder << "[url = " << location.url_ << ", access_hash = " << location.access_hash_ << "]";
+}
+
+struct CommonRemoteFileLocation {
+  int64 id_;
+  int64 access_hash_;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    using td::store;
+    store(id_, storer);
+    store(access_hash_, storer);
+  }
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    using td::parse;
+    parse(id_, parser);
+    parse(access_hash_, parser);
+  }
+  struct AsKey {
+    const CommonRemoteFileLocation &key;
+    template <class StorerT>
+    void store(StorerT &storer) const {
+      td::store(key.id_, storer);
+    }
+  };
+  AsKey as_key() const {
+    return AsKey{*this};
+  }
+  bool operator<(const CommonRemoteFileLocation &other) const {
+    return std::tie(id_) < std::tie(other.id_);
+  }
+  bool operator==(const CommonRemoteFileLocation &other) const {
+    return std::tie(id_) == std::tie(other.id_);
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &string_builder, const CommonRemoteFileLocation &location) {
+  return string_builder << "[id = " << location.id_ << ", access_hash = " << location.access_hash_ << "]";
+}
+
+class FullRemoteFileLocation {
+ public:
+  FileType file_type_{FileType::None};
+
+ private:
+  static constexpr int32 WEB_LOCATION_FLAG = 1 << 24;
+  bool web_location_flag_{false};
+  DcId dc_id_;
+  enum class LocationType { Web, Photo, Common, None };
+  Variant<WebRemoteFileLocation, PhotoRemoteFileLocation, CommonRemoteFileLocation> variant_;
+
+  LocationType location_type() const {
+    if (is_web()) {
+      return LocationType::Web;
+    }
+    switch (file_type_) {
+      case FileType::Photo:
+      case FileType::ProfilePhoto:
+      case FileType::Thumbnail:
+      case FileType::EncryptedThumbnail:
+      case FileType::Wallpaper:
+        return LocationType::Photo;
+      case FileType::Video:
+      case FileType::VoiceNote:
+      case FileType::Document:
+      case FileType::Sticker:
+      case FileType::Audio:
+      case FileType::Animation:
+      case FileType::Encrypted:
+      case FileType::VideoNote:
+        return LocationType::Common;
+      case FileType::None:
+      case FileType::Size:
+      default:
+        UNREACHABLE();
+      case FileType::Temp:
+        return LocationType::None;
+    }
+  }
+
+  WebRemoteFileLocation &web() {
+    return variant_.get<WebRemoteFileLocation>();
+  }
+  PhotoRemoteFileLocation &photo() {
+    return variant_.get<PhotoRemoteFileLocation>();
+  }
+  CommonRemoteFileLocation &common() {
+    return variant_.get<CommonRemoteFileLocation>();
+  }
+  const WebRemoteFileLocation &web() const {
+    return variant_.get<WebRemoteFileLocation>();
+  }
+  const PhotoRemoteFileLocation &photo() const {
+    return variant_.get<PhotoRemoteFileLocation>();
+  }
+  const CommonRemoteFileLocation &common() const {
+    return variant_.get<CommonRemoteFileLocation>();
+  }
+
+  friend StringBuilder &operator<<(StringBuilder &string_builder,
+                                   const FullRemoteFileLocation &full_remote_file_location);
+
+  int32 full_type() const {
+    auto type = static_cast<int32>(file_type_);
+    if (is_web()) {
+      type |= WEB_LOCATION_FLAG;
+    }
+    return type;
+  }
+
+ public:
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    using ::td::store;
+    store(full_type(), storer);
+    store(dc_id_.get_value(), storer);
+    variant_.visit([&](auto &&value) {
+      using td::store;
+      store(value, storer);
+    });
+  }
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    using ::td::parse;
+    int32 raw_type;
+    parse(raw_type, parser);
+    web_location_flag_ = (raw_type & WEB_LOCATION_FLAG) != 0;
+    raw_type &= ~WEB_LOCATION_FLAG;
+    if (raw_type < 0 || raw_type >= static_cast<int32>(FileType::Size)) {
+      return parser.set_error("Invalid FileType in FullRemoteFileLocation");
+    }
+    file_type_ = static_cast<FileType>(raw_type);
+    int32 dc_id_value;
+    parse(dc_id_value, parser);
+    dc_id_ = DcId::from_value(dc_id_value);
+
+    switch (location_type()) {
+      case LocationType::Web: {
+        variant_ = WebRemoteFileLocation();
+        return web().parse(parser);
+      }
+      case LocationType::Photo: {
+        variant_ = PhotoRemoteFileLocation();
+        return photo().parse(parser);
+      }
+      case LocationType::Common: {
+        variant_ = CommonRemoteFileLocation();
+        return common().parse(parser);
+      }
+      case LocationType::None: {
+        break;
+      }
+    }
+    parser.set_error("Invalid FileType in FullRemoteFileLocation");
+  }
+
+  struct AsKey {
+    const FullRemoteFileLocation &key;
+    template <class StorerT>
+    void store(StorerT &storer) const {
+      using td::store;
+      store(key.full_type(), storer);
+      key.variant_.visit([&](auto &&value) {
+        using td::store;
+        store(value.as_key(), storer);
+      });
+    }
+  };
+  AsKey as_key() const {
+    return AsKey{*this};
+  }
+
+  DcId get_dc_id() const {
+    return dc_id_;
+  }
+  int64 get_access_hash() const {
+    switch (location_type()) {
+      case LocationType::Photo:
+        return photo().access_hash_;
+      case LocationType::Common:
+        return common().access_hash_;
+      case LocationType::Web:
+        return web().access_hash_;
+      case LocationType::None:
+      default:
+        UNREACHABLE();
+        return 0;
+    }
+  }
+  int64 get_id() const {
+    switch (location_type()) {
+      case LocationType::Photo:
+        return photo().id_;
+      case LocationType::Common:
+        return common().id_;
+      case LocationType::Web:
+      case LocationType::None:
+      default:
+        UNREACHABLE();
+        return 0;
+    }
+  }
+  string get_url() const {
+    if (is_web()) {
+      return web().url_;
+    }
+
+    return string();
+  }
+
+  bool is_web() const {
+    return web_location_flag_;
+  }
+  bool is_photo() const {
+    return location_type() == LocationType::Photo;
+  }
+  bool is_common() const {
+    return location_type() == LocationType::Common;
+  }
+  bool is_encrypted() const {
+    return file_type_ == FileType::Encrypted;
+  }
+
+  tl_object_ptr<telegram_api::inputWebFileLocation> as_input_web_file_location() const {
+    CHECK(is_web());
+    return make_tl_object<telegram_api::inputWebFileLocation>(web().url_, web().access_hash_);
+  }
+  tl_object_ptr<telegram_api::InputFileLocation> as_input_file_location() const {
+    switch (location_type()) {
+      case LocationType::Photo:
+        return make_tl_object<telegram_api::inputFileLocation>(photo().volume_id_, photo().local_id_, photo().secret_);
+      case LocationType::Common:
+        if (is_encrypted()) {
+          return make_tl_object<telegram_api::inputEncryptedFileLocation>(common().id_, common().access_hash_);
+        } else {
+          return make_tl_object<telegram_api::inputDocumentFileLocation>(common().id_, common().access_hash_, 0);
+        }
+      case LocationType::Web:
+      case LocationType::None:
+      default:
+        UNREACHABLE();
+        return nullptr;
+    }
+  }
+
+  tl_object_ptr<telegram_api::InputDocument> as_input_document() const {
+    CHECK(is_common());
+    LOG_IF(ERROR, is_encrypted()) << "Can't call as_input_document on an encrypted file";
+    return make_tl_object<telegram_api::inputDocument>(common().id_, common().access_hash_);
+  }
+
+  tl_object_ptr<telegram_api::InputPhoto> as_input_photo() const {
+    CHECK(is_photo());
+    return make_tl_object<telegram_api::inputPhoto>(photo().id_, photo().access_hash_);
+  }
+
+  tl_object_ptr<telegram_api::InputEncryptedFile> as_input_encrypted_file() const {
+    CHECK(is_encrypted()) << "Can't call as_input_encrypted_file on a non-encrypted file";
+    return make_tl_object<telegram_api::inputEncryptedFile>(common().id_, common().access_hash_);
+  }
+
+  // TODO: this constructor is just for immediate unserialize
+  FullRemoteFileLocation() = default;
+  FullRemoteFileLocation(FileType file_type, int64 id, int64 access_hash, int32 local_id, int64 volume_id, int64 secret,
+                         DcId dc_id)
+      : file_type_(file_type)
+      , dc_id_(dc_id)
+      , variant_(PhotoRemoteFileLocation{id, access_hash, volume_id, secret, local_id}) {
+    CHECK(is_photo());
+  }
+  FullRemoteFileLocation(FileType file_type, int64 id, int64 access_hash, DcId dc_id)
+      : file_type_(file_type), dc_id_(dc_id), variant_(CommonRemoteFileLocation{id, access_hash}) {
+    CHECK(is_common());
+  }
+  FullRemoteFileLocation(FileType file_type, string url, int64 access_hash, DcId dc_id)
+      : file_type_(file_type)
+      , web_location_flag_{true}
+      , dc_id_(dc_id)
+      , variant_(WebRemoteFileLocation{std::move(url), access_hash}) {
+    CHECK(is_web());
+    CHECK(!web().url_.empty());
+  }
+
+  bool operator<(const FullRemoteFileLocation &other) const {
+    if (full_type() != other.full_type()) {
+      return full_type() < other.full_type();
+    }
+    if (dc_id_ != other.dc_id_) {
+      return dc_id_ < other.dc_id_;
+    }
+    switch (location_type()) {
+      case LocationType::Photo:
+        return photo() < other.photo();
+      case LocationType::Common:
+        return common() < other.common();
+      case LocationType::Web:
+        return web() < other.web();
+      case LocationType::None:
+      default:
+        UNREACHABLE();
+        return false;
+    }
+  }
+  bool operator==(const FullRemoteFileLocation &other) const {
+    if (full_type() != other.full_type()) {
+      return false;
+    }
+    if (dc_id_ != other.dc_id_) {
+      return false;
+    }
+    switch (location_type()) {
+      case LocationType::Photo:
+        return photo() == other.photo();
+      case LocationType::Common:
+        return common() == other.common();
+      case LocationType::Web:
+        return web() == other.web();
+      case LocationType::None:
+      default:
+        UNREACHABLE();
+        return false;
+    }
+  }
+
+  static const int32 KEY_MAGIC = 0x64374632;
+};
+
+inline StringBuilder &operator<<(StringBuilder &string_builder,
+                                 const FullRemoteFileLocation &full_remote_file_location) {
+  string_builder << "[" << file_type_name[static_cast<int32>(full_remote_file_location.file_type_)] << ", "
+                 << full_remote_file_location.get_dc_id() << ", location = ";
+
+  if (full_remote_file_location.is_web()) {
+    string_builder << full_remote_file_location.web();
+  } else if (full_remote_file_location.is_photo()) {
+    string_builder << full_remote_file_location.photo();
+  } else if (full_remote_file_location.is_common()) {
+    string_builder << full_remote_file_location.common();
+  }
+
+  return string_builder << "]";
+}
+
+class RemoteFileLocation {
+ public:
+  enum class Type : int32 { Empty, Partial, Full };
+
+  Type type() const {
+    return static_cast<Type>(variant_.get_offset());
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    storer.store_int(variant_.get_offset());
+    bool ok{false};
+    variant_.visit([&](auto &&value) {
+      using td::store;
+      store(value, storer);
+      ok = true;
+    });
+    CHECK(ok);
+  }
+  PartialRemoteFileLocation &partial() {
+    return variant_.get<1>();
+  }
+  FullRemoteFileLocation &full() {
+    return variant_.get<2>();
+  }
+  const PartialRemoteFileLocation &partial() const {
+    return variant_.get<1>();
+  }
+  const FullRemoteFileLocation &full() const {
+    return variant_.get<2>();
+  }
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    auto type = static_cast<Type>(parser.fetch_int());
+    switch (type) {
+      case Type::Empty: {
+        variant_ = EmptyRemoteFileLocation();
+        return;
+      }
+      case Type::Partial: {
+        variant_ = PartialRemoteFileLocation();
+        return partial().parse(parser);
+      }
+      case Type::Full: {
+        variant_ = FullRemoteFileLocation();
+        return full().parse(parser);
+      }
+    }
+    parser.set_error("Invalid type in RemoteFileLocation");
+  }
+
+  RemoteFileLocation() : variant_{EmptyRemoteFileLocation{}} {
+  }
+  explicit RemoteFileLocation(const FullRemoteFileLocation &full) : variant_(full) {
+  }
+  explicit RemoteFileLocation(const PartialRemoteFileLocation &partial) : variant_(partial) {
+  }
+  RemoteFileLocation(FileType file_type, int64 id, int64 access_hash, int32 local_id, int64 volume_id, int64 secret,
+                     DcId dc_id)
+      : variant_(FullRemoteFileLocation{file_type, id, access_hash, local_id, volume_id, secret, dc_id}) {
+  }
+  RemoteFileLocation(FileType file_type, int64 id, int64 access_hash, DcId dc_id)
+      : variant_(FullRemoteFileLocation{file_type, id, access_hash, dc_id}) {
+  }
+
+ private:
+  Variant<EmptyRemoteFileLocation, PartialRemoteFileLocation, FullRemoteFileLocation> variant_;
+
+  friend bool operator==(const RemoteFileLocation &lhs, const RemoteFileLocation &rhs);
+};
+
+inline bool operator==(const RemoteFileLocation &lhs, const RemoteFileLocation &rhs) {
+  return lhs.variant_ == rhs.variant_;
+}
+
+inline bool operator!=(const RemoteFileLocation &lhs, const RemoteFileLocation &rhs) {
+  return !(lhs == rhs);
+}
+
+struct EmptyLocalFileLocation {
+  template <class StorerT>
+  void store(StorerT &storer) const {
+  }
+  template <class ParserT>
+  void parse(ParserT &parser) {
+  }
+};
+
+inline bool operator==(const EmptyLocalFileLocation &lhs, const EmptyLocalFileLocation &rhs) {
+  return true;
+}
+
+inline bool operator!=(const EmptyLocalFileLocation &lhs, const EmptyLocalFileLocation &rhs) {
+  return !(lhs == rhs);
+}
+
+struct PartialLocalFileLocation {
+  FileType file_type_;
+  string path_;
+  int32 part_size_;
+  int32 ready_part_count_;
+  string iv_;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    using td::store;
+    store(file_type_, storer);
+    store(path_, storer);
+    store(part_size_, storer);
+    store(ready_part_count_, storer);
+    store(iv_, storer);
+  }
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    using td::parse;
+    parse(file_type_, parser);
+    if (file_type_ < FileType::Thumbnail || file_type_ >= FileType::Size) {
+      return parser.set_error("Invalid type in PartialLocalFileLocation");
+    }
+    parse(path_, parser);
+    parse(part_size_, parser);
+    parse(ready_part_count_, parser);
+    parse(iv_, parser);
+  }
+};
+
+inline bool operator==(const PartialLocalFileLocation &lhs, const PartialLocalFileLocation &rhs) {
+  return lhs.file_type_ == rhs.file_type_ && lhs.path_ == rhs.path_ && lhs.part_size_ == rhs.part_size_ &&
+         lhs.ready_part_count_ == rhs.ready_part_count_ && lhs.iv_ == rhs.iv_;
+}
+
+inline bool operator!=(const PartialLocalFileLocation &lhs, const PartialLocalFileLocation &rhs) {
+  return !(lhs == rhs);
+}
+
+struct FullLocalFileLocation {
+  FileType file_type_;
+  string path_;
+  uint64 mtime_nsec_;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    using td::store;
+    store(file_type_, storer);
+    store(mtime_nsec_, storer);
+    store(path_, storer);
+  }
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    using td::parse;
+    parse(file_type_, parser);
+    if (file_type_ < FileType::Thumbnail || file_type_ >= FileType::Size) {
+      return parser.set_error("Invalid type in FullLocalFileLocation");
+    }
+    parse(mtime_nsec_, parser);
+    parse(path_, parser);
+  }
+  const FullLocalFileLocation &as_key() const {
+    return *this;
+  }
+
+  // TODO: remove this constructor
+  FullLocalFileLocation() : file_type_(FileType::Photo) {
+  }
+  FullLocalFileLocation(FileType file_type, string path, uint64 mtime_nsec)
+      : file_type_(file_type), path_(std::move(path)), mtime_nsec_(mtime_nsec) {
+  }
+
+  static const int32 KEY_MAGIC = 0x84373817;
+};
+
+inline bool operator<(const FullLocalFileLocation &lhs, const FullLocalFileLocation &rhs) {
+  return std::tie(lhs.file_type_, lhs.mtime_nsec_, lhs.path_) < std::tie(rhs.file_type_, rhs.mtime_nsec_, rhs.path_);
+}
+
+inline bool operator==(const FullLocalFileLocation &lhs, const FullLocalFileLocation &rhs) {
+  return std::tie(lhs.file_type_, lhs.mtime_nsec_, lhs.path_) == std::tie(rhs.file_type_, rhs.mtime_nsec_, rhs.path_);
+}
+
+inline bool operator!=(const FullLocalFileLocation &lhs, const FullLocalFileLocation &rhs) {
+  return !(lhs == rhs);
+}
+
+inline StringBuilder &operator<<(StringBuilder &sb, const FullLocalFileLocation &location) {
+  return sb << tag("path", location.path_);
+}
+
+class LocalFileLocation {
+ public:
+  enum class Type : int32 { Empty, Partial, Full };
+
+  Type type() const {
+    return static_cast<Type>(variant_.get_offset());
+  }
+
+  PartialLocalFileLocation &partial() {
+    return variant_.get<1>();
+  }
+  FullLocalFileLocation &full() {
+    return variant_.get<2>();
+  }
+  const PartialLocalFileLocation &partial() const {
+    return variant_.get<1>();
+  }
+  const FullLocalFileLocation &full() const {
+    return variant_.get<2>();
+  }
+
+  CSlice file_name() const {
+    switch (type()) {
+      case Type::Partial:
+        return partial().path_;
+      case Type::Full:
+        return full().path_;
+      case Type::Empty:
+      default:
+        return CSlice();
+    }
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    using td::store;
+    store(variant_.get_offset(), storer);
+    variant_.visit([&](auto &&value) {
+      using td::store;
+      store(value, storer);
+    });
+  }
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    using td::parse;
+    auto type = static_cast<Type>(parser.fetch_int());
+    switch (type) {
+      case Type::Empty:
+        variant_ = EmptyLocalFileLocation();
+        return;
+      case Type::Partial:
+        variant_ = PartialLocalFileLocation();
+        return parse(partial(), parser);
+      case Type::Full:
+        variant_ = FullLocalFileLocation();
+        return parse(full(), parser);
+    }
+    return parser.set_error("Invalid type in LocalFileLocation");
+  }
+
+  LocalFileLocation() : variant_{EmptyLocalFileLocation()} {
+  }
+  explicit LocalFileLocation(const PartialLocalFileLocation &partial) : variant_(partial) {
+  }
+  explicit LocalFileLocation(const FullLocalFileLocation &full) : variant_(full) {
+  }
+  LocalFileLocation(FileType file_type, string path, uint64 mtime_nsec)
+      : variant_(FullLocalFileLocation{file_type, std::move(path), mtime_nsec}) {
+  }
+
+ private:
+  Variant<EmptyLocalFileLocation, PartialLocalFileLocation, FullLocalFileLocation> variant_;
+
+  friend bool operator==(const LocalFileLocation &lhs, const LocalFileLocation &rhs);
+};
+
+inline bool operator==(const LocalFileLocation &lhs, const LocalFileLocation &rhs) {
+  return lhs.variant_ == rhs.variant_;
+}
+
+inline bool operator!=(const LocalFileLocation &lhs, const LocalFileLocation &rhs) {
+  return !(lhs == rhs);
+}
+
+struct FullGenerateFileLocation {
+  FileType file_type_{FileType::None};
+  string original_path_;
+  string conversion_;
+  static const int32 KEY_MAGIC = 0x8b60a1c8;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    using td::store;
+    store(file_type_, storer);
+    store(original_path_, storer);
+    store(conversion_, storer);
+  }
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    using td::parse;
+    parse(file_type_, parser);
+    parse(original_path_, parser);
+    parse(conversion_, parser);
+  }
+
+  const FullGenerateFileLocation &as_key() const {
+    return *this;
+  }
+  FullGenerateFileLocation() = default;
+  FullGenerateFileLocation(FileType file_type, string original_path, string conversion)
+      : file_type_(file_type), original_path_(std::move(original_path)), conversion_(std::move(conversion)) {
+  }
+};
+
+inline bool operator<(const FullGenerateFileLocation &lhs, const FullGenerateFileLocation &rhs) {
+  return std::tie(lhs.file_type_, lhs.original_path_, lhs.conversion_) <
+         std::tie(rhs.file_type_, rhs.original_path_, rhs.conversion_);
+}
+
+inline bool operator==(const FullGenerateFileLocation &lhs, const FullGenerateFileLocation &rhs) {
+  return std::tie(lhs.file_type_, lhs.original_path_, lhs.conversion_) ==
+         std::tie(rhs.file_type_, rhs.original_path_, rhs.conversion_);
+}
+
+inline bool operator!=(const FullGenerateFileLocation &lhs, const FullGenerateFileLocation &rhs) {
+  return !(lhs == rhs);
+}
+
+inline StringBuilder &operator<<(StringBuilder &string_builder,
+                                 const FullGenerateFileLocation &full_generated_file_location) {
+  return string_builder << "["
+                        << tag("file_type", file_type_name[static_cast<int32>(full_generated_file_location.file_type_)])
+                        << tag("original_path", full_generated_file_location.original_path_)
+                        << tag("conversion", full_generated_file_location.conversion_) << "]";
+}
+
+class GenerateFileLocation {
+ public:
+  enum class Type : int32 { Empty, Full };
+
+  Type type() const {
+    return type_;
+  }
+
+  FullGenerateFileLocation &full() {
+    CHECK(type_ == Type::Full);
+    return full_;
+  }
+  const FullGenerateFileLocation &full() const {
+    CHECK(type_ == Type::Full);
+    return full_;
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    td::store(type_, storer);
+    switch (type_) {
+      case Type::Empty:
+        return;
+      case Type::Full:
+        return td::store(full_, storer);
+    }
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    td::parse(type_, parser);
+    switch (type_) {
+      case Type::Empty:
+        return;
+      case Type::Full:
+        return td::parse(full_, parser);
+    }
+    return parser.set_error("Invalid type in GenerateFileLocation");
+  }
+
+  GenerateFileLocation() : type_(Type::Empty) {
+  }
+
+  explicit GenerateFileLocation(const FullGenerateFileLocation &full) : type_(Type::Full), full_(full) {
+  }
+
+  GenerateFileLocation(FileType file_type, string original_path, string conversion)
+      : type_(Type::Full), full_{file_type, std::move(original_path), std::move(conversion)} {
+  }
+
+ private:
+  Type type_;
+  FullGenerateFileLocation full_;
+};
+
+inline bool operator==(const GenerateFileLocation &lhs, const GenerateFileLocation &rhs) {
+  if (lhs.type() != rhs.type()) {
+    return false;
+  }
+  switch (lhs.type()) {
+    case GenerateFileLocation::Type::Empty:
+      return true;
+    case GenerateFileLocation::Type::Full:
+      return lhs.full() == rhs.full();
+  }
+  UNREACHABLE();
+  return false;
+}
+
+inline bool operator!=(const GenerateFileLocation &lhs, const GenerateFileLocation &rhs) {
+  return !(lhs == rhs);
+}
+
+class FileData {
+ public:
+  DialogId owner_dialog_id_;
+  uint64 pmc_id_ = 0;
+  RemoteFileLocation remote_;
+  LocalFileLocation local_;
+  unique_ptr<FullGenerateFileLocation> generate_;
+  int64 size_ = 0;
+  int64 expected_size_ = 0;
+  string remote_name_;
+  string url_;
+  FileEncryptionKey encryption_key_;
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    using ::td::store;
+    bool has_owner_dialog_id = owner_dialog_id_.is_valid();
+    bool has_expected_size = size_ == 0 && expected_size_ != 0;
+    BEGIN_STORE_FLAGS();
+    STORE_FLAG(has_owner_dialog_id);
+    STORE_FLAG(has_expected_size);
+    END_STORE_FLAGS();
+
+    if (has_owner_dialog_id) {
+      store(owner_dialog_id_, storer);
+    }
+    store(pmc_id_, storer);
+    store(remote_, storer);
+    store(local_, storer);
+    auto generate = generate_ == nullptr ? GenerateFileLocation() : GenerateFileLocation(*generate_);
+    store(generate, storer);
+    if (has_expected_size) {
+      store(expected_size_, storer);
+    } else {
+      store(size_, storer);
+    }
+    store(remote_name_, storer);
+    store(url_, storer);
+    store(encryption_key_, storer);
+  }
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    using ::td::parse;
+    bool has_owner_dialog_id;
+    bool has_expected_size;
+    BEGIN_PARSE_FLAGS();
+    PARSE_FLAG(has_owner_dialog_id);
+    PARSE_FLAG(has_expected_size);
+    END_PARSE_FLAGS();
+
+    if (has_owner_dialog_id) {
+      parse(owner_dialog_id_, parser);
+    }
+    parse(pmc_id_, parser);
+    parse(remote_, parser);
+    parse(local_, parser);
+    GenerateFileLocation generate;
+    parse(generate, parser);
+    if (generate.type() == GenerateFileLocation::Type::Full) {
+      generate_ = std::make_unique<FullGenerateFileLocation>(generate.full());
+    } else {
+      generate_ = nullptr;
+    }
+    if (has_expected_size) {
+      parse(expected_size_, parser);
+    } else {
+      parse(size_, parser);
+    }
+    parse(remote_name_, parser);
+    parse(url_, parser);
+    parse(encryption_key_, parser);
+  }
+};
+inline StringBuilder &operator<<(StringBuilder &sb, const FileData &file_data) {
+  sb << "[" << tag("remote_name", file_data.remote_name_) << " " << file_data.owner_dialog_id_ << " "
+     << tag("size", file_data.size_) << tag("expected_size", file_data.expected_size_);
+  if (!file_data.url_.empty()) {
+    sb << tag("url", file_data.url_);
+  }
+  if (file_data.local_.type() == LocalFileLocation::Type::Full) {
+    sb << " local " << file_data.local_.full();
+  }
+  if (file_data.generate_ != nullptr) {
+    sb << " generate " << *file_data.generate_;
+  }
+  if (file_data.remote_.type() == RemoteFileLocation::Type::Full) {
+    sb << " remote " << file_data.remote_.full();
+  }
+  return sb << "]";
+}
+
+template <class T>
+string as_key(const T &object) {
+  TlStorerCalcLength calc_length;
+  calc_length.store_int(0);
+  object.as_key().store(calc_length);
+
+  BufferSlice key_buffer{calc_length.get_length()};
+  auto key = key_buffer.as_slice();
+  TlStorerUnsafe storer(key.begin());
+  storer.store_int(T::KEY_MAGIC);
+  object.as_key().store(storer);
+  return key.str();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileManager.cpp b/libs/tdlib/td/td/telegram/files/FileManager.cpp
new file mode 100644
index 0000000000..dc5e2d1caf
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileManager.cpp
@@ -0,0 +1,2356 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/files/FileManager.h"
+
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/files/FileLoaderUtils.h"
+#include "td/telegram/files/FileLocation.h"
+#include "td/telegram/files/FileUploader.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/misc.h"
+#include "td/telegram/Td.h"
+
+#include "td/utils/base64.h"
+#include "td/utils/format.h"
+#include "td/utils/HttpUrl.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/PathView.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/port/path.h"
+#include "td/utils/port/Stat.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/tl_helpers.h"
+
+#include <algorithm>
+#include <limits>
+#include <tuple>
+#include <utility>
+
+namespace td {
+
+static int VERBOSITY_NAME(update_file) = VERBOSITY_NAME(INFO);
+
+FileNode *FileNodePtr::operator->() const {
+  return get();
+}
+
+FileNode &FileNodePtr::operator*() const {
+  return *get();
+}
+
+FileNode *FileNodePtr::get() const {
+  auto res = get_unsafe();
+  CHECK(res);
+  return res;
+}
+
+FullRemoteFileLocation *FileNodePtr::get_remote() const {
+  return file_manager_->get_remote(file_id_.get_remote());
+}
+
+FileNode *FileNodePtr::get_unsafe() const {
+  CHECK(file_manager_ != nullptr);
+  return file_manager_->get_file_node_raw(file_id_);
+}
+
+FileNodePtr::operator bool() const {
+  return file_manager_ != nullptr && get_unsafe() != nullptr;
+}
+
+void FileNode::set_local_location(const LocalFileLocation &local, int64 ready_size) {
+  if (local_ready_size_ != ready_size) {
+    local_ready_size_ = ready_size;
+    VLOG(update_file) << "File " << main_file_id_ << " has changed local ready size";
+    on_info_changed();
+  }
+  if (local_ != local) {
+    VLOG(update_file) << "File " << main_file_id_ << " has changed local location";
+    local_ = local;
+    on_changed();
+  }
+}
+
+void FileNode::set_remote_location(const RemoteFileLocation &remote, FileLocationSource source, int64 ready_size) {
+  if (remote_ready_size_ != ready_size) {
+    remote_ready_size_ = ready_size;
+    VLOG(update_file) << "File " << main_file_id_ << " has changed remote ready size";
+    on_info_changed();
+  }
+  if (remote_ == remote) {
+    if (remote_.type() == RemoteFileLocation::Type::Full) {
+      if (remote_.full().get_access_hash() == remote.full().get_access_hash()) {
+        return;
+      }
+    } else {
+      return;
+    }
+  }
+
+  VLOG(update_file) << "File " << main_file_id_ << " has changed remote location";
+  remote_ = remote;
+  remote_source_ = source;
+  on_changed();
+}
+
+void FileNode::set_generate_location(unique_ptr<FullGenerateFileLocation> &&generate) {
+  bool is_changed = generate_ == nullptr ? generate != nullptr : generate == nullptr || *generate_ != *generate;
+  if (is_changed) {
+    generate_ = std::move(generate);
+    on_pmc_changed();
+  }
+}
+
+void FileNode::set_size(int64 size) {
+  if (size_ != size) {
+    VLOG(update_file) << "File " << main_file_id_ << " has changed size to " << size;
+    size_ = size;
+    on_changed();
+  }
+}
+
+void FileNode::set_expected_size(int64 expected_size) {
+  if (expected_size_ != expected_size) {
+    VLOG(update_file) << "File " << main_file_id_ << " has changed expected size to " << expected_size;
+    expected_size_ = expected_size;
+    on_changed();
+  }
+}
+
+void FileNode::set_remote_name(string remote_name) {
+  if (remote_name_ != remote_name) {
+    remote_name_ = std::move(remote_name);
+    on_pmc_changed();
+  }
+}
+
+void FileNode::set_url(string url) {
+  if (url_ != url) {
+    VLOG(update_file) << "File " << main_file_id_ << " has changed URL to " << url;
+    url_ = std::move(url);
+    on_changed();
+  }
+}
+
+void FileNode::set_owner_dialog_id(DialogId owner_id) {
+  if (owner_dialog_id_ != owner_id) {
+    owner_dialog_id_ = owner_id;
+    on_pmc_changed();
+  }
+}
+
+void FileNode::set_encryption_key(FileEncryptionKey key) {
+  if (encryption_key_ != key) {
+    encryption_key_ = std::move(key);
+    on_pmc_changed();
+  }
+}
+
+void FileNode::set_download_priority(int8 priority) {
+  if ((download_priority_ == 0) != (priority == 0)) {
+    VLOG(update_file) << "File " << main_file_id_ << " has changed download priority to " << priority;
+    on_info_changed();
+  }
+  download_priority_ = priority;
+}
+
+void FileNode::set_upload_priority(int8 priority) {
+  if ((upload_priority_ == 0) != (priority == 0)) {
+    VLOG(update_file) << "File " << main_file_id_ << " has changed upload priority to " << priority;
+    on_info_changed();
+  }
+  upload_priority_ = priority;
+}
+
+void FileNode::set_generate_priority(int8 download_priority, int8 upload_priority) {
+  if ((download_priority_ == 0) != (download_priority == 0) || (upload_priority_ == 0) != (upload_priority == 0)) {
+    VLOG(update_file) << "File " << main_file_id_ << " has changed generate priority to " << download_priority << "/"
+                      << upload_priority;
+    on_info_changed();
+  }
+  generate_priority_ = max(download_priority, upload_priority);
+  generate_download_priority_ = download_priority;
+  generate_upload_priority_ = upload_priority;
+}
+
+void FileNode::on_changed() {
+  on_pmc_changed();
+  on_info_changed();
+}
+void FileNode::on_info_changed() {
+  info_changed_flag_ = true;
+}
+void FileNode::on_pmc_changed() {
+  pmc_changed_flag_ = true;
+}
+
+bool FileNode::need_info_flush() const {
+  return info_changed_flag_;
+}
+
+bool FileNode::need_pmc_flush() const {
+  if (!pmc_changed_flag_) {
+    return false;
+  }
+
+  // already in pmc
+  if (pmc_id_ != 0) {
+    return true;
+  }
+
+  // We must save encryption key
+  if (!encryption_key_.empty()) {
+    // && remote_.type() != RemoteFileLocation::Type::Empty
+    return true;
+  }
+
+  bool has_generate_location = generate_ != nullptr;
+  // Do not save "#file_id#" conversion.
+  if (has_generate_location && begins_with(generate_->conversion_, "#file_id#")) {
+    has_generate_location = false;
+  }
+
+  if (remote_.type() == RemoteFileLocation::Type::Full &&
+      (has_generate_location || local_.type() != LocalFileLocation::Type::Empty)) {
+    return true;
+  }
+  if (local_.type() == LocalFileLocation::Type::Full &&
+      (has_generate_location || remote_.type() != RemoteFileLocation::Type::Empty)) {
+    return true;
+  }
+
+  // TODO: Generate location with constant conversion
+
+  return false;
+}
+
+void FileNode::on_pmc_flushed() {
+  pmc_changed_flag_ = false;
+}
+void FileNode::on_info_flushed() {
+  info_changed_flag_ = false;
+}
+
+string FileNode::suggested_name() const {
+  if (!remote_name_.empty()) {
+    return remote_name_;
+  }
+  if (!url_.empty()) {
+    auto file_name = get_url_file_name(url_);
+    if (!file_name.empty()) {
+      return file_name;
+    }
+  }
+  if (generate_ != nullptr) {
+    if (!generate_->original_path_.empty()) {
+      return generate_->original_path_;
+    }
+  }
+  return local_.file_name().str();
+}
+
+/*** FileView ***/
+bool FileView::has_local_location() const {
+  return node_->local_.type() == LocalFileLocation::Type::Full;
+}
+const FullLocalFileLocation &FileView::local_location() const {
+  CHECK(has_local_location());
+  return node_->local_.full();
+}
+bool FileView::has_remote_location() const {
+  return node_->remote_.type() == RemoteFileLocation::Type::Full;
+}
+const FullRemoteFileLocation &FileView::remote_location() const {
+  CHECK(has_remote_location());
+  auto *remote = node_.get_remote();
+  if (remote) {
+    return *remote;
+  }
+  return node_->remote_.full();
+}
+bool FileView::has_generate_location() const {
+  return node_->generate_ != nullptr;
+}
+const FullGenerateFileLocation &FileView::generate_location() const {
+  CHECK(has_generate_location());
+  return *node_->generate_;
+}
+
+int64 FileView::size() const {
+  return node_->size_;
+}
+
+int64 FileView::expected_size() const {
+  if (node_->size_ != 0) {
+    return node_->size_;
+  }
+  return node_->expected_size_;
+}
+
+bool FileView::is_downloading() const {
+  return node_->download_priority_ != 0 || node_->generate_download_priority_ != 0;
+}
+
+int64 FileView::local_size() const {
+  switch (node_->local_.type()) {
+    case LocalFileLocation::Type::Full:
+      return node_->size_;
+    case LocalFileLocation::Type::Partial:
+      return node_->local_.partial().part_size_ * node_->local_.partial().ready_part_count_;
+    default:
+      return 0;
+  }
+}
+int64 FileView::local_total_size() const {
+  switch (node_->local_.type()) {
+    case LocalFileLocation::Type::Empty:
+      return 0;
+    case LocalFileLocation::Type::Full:
+      return node_->size_;
+    case LocalFileLocation::Type::Partial:
+      return max(static_cast<int64>(node_->local_.partial().part_size_) * node_->local_.partial().ready_part_count_,
+                 node_->local_ready_size_);
+    default:
+      UNREACHABLE();
+      return 0;
+  }
+}
+
+bool FileView::is_uploading() const {
+  return node_->upload_priority_ != 0 || node_->generate_upload_priority_ != 0;
+}
+
+int64 FileView::remote_size() const {
+  switch (node_->remote_.type()) {
+    case RemoteFileLocation::Type::Full:
+      return node_->size_;
+    case RemoteFileLocation::Type::Partial: {
+      auto res =
+          max(static_cast<int64>(node_->remote_.partial().part_size_) * node_->remote_.partial().ready_part_count_,
+              node_->remote_ready_size_);
+      if (size() != 0 && size() < res) {
+        res = size();
+      }
+      return res;
+    }
+    default:
+      return 0;
+  }
+}
+
+string FileView::path() const {
+  switch (node_->local_.type()) {
+    case LocalFileLocation::Type::Full:
+      return node_->local_.full().path_;
+    case LocalFileLocation::Type::Partial:
+      return node_->local_.partial().path_;
+    default:
+      return "";
+  }
+}
+
+bool FileView::has_url() const {
+  return !node_->url_.empty();
+}
+
+const string &FileView::url() const {
+  return node_->url_;
+}
+
+const string &FileView::remote_name() const {
+  return node_->remote_name_;
+}
+
+string FileView::suggested_name() const {
+  return node_->suggested_name();
+}
+
+DialogId FileView::owner_dialog_id() const {
+  return node_->owner_dialog_id_;
+}
+
+bool FileView::get_by_hash() const {
+  return node_->get_by_hash_;
+}
+
+FileView::FileView(ConstFileNodePtr node) : node_(node) {
+}
+
+bool FileView::empty() const {
+  return !node_;
+}
+
+bool FileView::can_download_from_server() const {
+  if (!has_remote_location()) {
+    return false;
+  }
+  if (remote_location().file_type_ == FileType::Encrypted && encryption_key().empty()) {
+    return false;
+  }
+  if (remote_location().get_dc_id().is_empty()) {
+    return false;
+  }
+  return true;
+}
+bool FileView::can_generate() const {
+  return has_generate_location();
+}
+
+bool FileView::can_delete() const {
+  if (has_local_location()) {
+    return begins_with(local_location().path_, get_files_dir(get_type()));
+  }
+  return node_->local_.type() == LocalFileLocation::Type::Partial;
+}
+
+/*** FileManager ***/
+namespace {
+void prepare_path_for_pmc(FileType file_type, string &path) {
+  path = PathView::relative(path, get_files_base_dir(file_type)).str();
+}
+}  // namespace
+
+FileManager::FileManager(std::unique_ptr<Context> context) : context_(std::move(context)) {
+  if (G()->parameters().use_file_db) {
+    file_db_ = G()->td_db()->get_file_db_shared();
+  }
+
+  parent_ = context_->create_reference();
+  next_file_id();
+  next_file_node_id();
+
+  std::vector<string> dirs;
+  auto create_dir = [&](CSlice path) {
+    dirs.push_back(path.str());
+    auto status = mkdir(path, 0750);
+    if (status.is_error()) {
+      auto r_stat = stat(path);
+      if (r_stat.is_ok() && r_stat.ok().is_dir_) {
+        LOG(ERROR) << "mkdir " << tag("path", path) << " failed " << status << ", but directory exists";
+      } else {
+        LOG(ERROR) << "mkdir " << tag("path", path) << " failed " << status;
+      }
+    }
+#if TD_ANDROID
+    FileFd::open(dirs.back() + ".nomedia", FileFd::Create | FileFd::Read).ignore();
+#endif
+  };
+  for (int i = 0; i < file_type_size; i++) {
+    auto path = get_files_dir(FileType(i));
+    create_dir(path);
+  }
+
+  // Create both temp dirs.
+  create_dir(get_files_temp_dir(FileType::Encrypted));
+  create_dir(get_files_temp_dir(FileType::Video));
+
+  G()->td_db()->with_db_path([this](CSlice path) { this->bad_paths_.insert(path.str()); });
+}
+
+void FileManager::init_actor() {
+  file_load_manager_ = create_actor_on_scheduler<FileLoadManager>("FileLoadManager", G()->get_slow_net_scheduler_id(),
+                                                                  actor_shared(this), context_->create_reference());
+  file_generate_manager_ = create_actor_on_scheduler<FileGenerateManager>(
+      "FileGenerateManager", G()->get_slow_net_scheduler_id(), context_->create_reference());
+}
+FileManager::~FileManager() {
+  // NB: As FileLoadManager callback is just "this" pointer, this event must be processed immediately.
+  send_closure(std::move(file_load_manager_), &FileLoadManager::close);
+}
+
+string FileManager::fix_file_extension(Slice file_name, Slice file_type, Slice file_extension) {
+  return (file_name.empty() ? file_type : file_name).str() + "." + file_extension.str();
+}
+
+string FileManager::get_file_name(FileType file_type, Slice path) {
+  PathView path_view(path);
+  auto file_name = path_view.file_name();
+  auto extension = path_view.extension();
+  switch (file_type) {
+    case FileType::Thumbnail:
+      if (extension != "jpg" && extension != "jpeg" && extension != "webp") {
+        return fix_file_extension(file_name, "thumbnail", "jpg");
+      }
+      break;
+    case FileType::ProfilePhoto:
+    case FileType::Photo:
+      if (extension != "jpg" && extension != "jpeg" && extension != "gif" && extension != "png" && extension != "tif" &&
+          extension != "bmp") {
+        return fix_file_extension(file_name, "photo", "jpg");
+      }
+      break;
+    case FileType::VoiceNote:
+      if (extension != "ogg" && extension != "oga" && extension != "mp3" && extension != "mpeg3" &&
+          extension != "m4a") {
+        return fix_file_extension(file_name, "voice", "oga");
+      }
+      break;
+    case FileType::Video:
+    case FileType::VideoNote:
+      if (extension != "mov" && extension != "3gp" && extension != "mpeg4" && extension != "mp4") {
+        return fix_file_extension(file_name, "video", "mp4");
+      }
+      break;
+    case FileType::Audio:
+      if (extension != "ogg" && extension != "oga" && extension != "mp3" && extension != "mpeg3" &&
+          extension != "m4a") {
+        return fix_file_extension(file_name, "audio", "mp3");
+      }
+      break;
+    case FileType::Document:
+    case FileType::Sticker:
+    case FileType::Animation:
+    case FileType::Encrypted:
+    case FileType::Temp:
+    case FileType::EncryptedThumbnail:
+    case FileType::Wallpaper:
+      break;
+    default:
+      UNREACHABLE();
+  }
+  return file_name.str();
+}
+
+Status FileManager::check_local_location(FullLocalFileLocation &location, int64 &size) {
+  constexpr int64 MAX_THUMBNAIL_SIZE = 200 * (1 << 10) /* 200KB */;
+  constexpr int64 MAX_FILE_SIZE = 1500 * (1 << 20) /* 1500MB */;
+
+  if (location.path_.empty()) {
+    return Status::Error("File must have non-empty path");
+  }
+  TRY_RESULT(path, realpath(location.path_, true));
+  if (bad_paths_.count(path) != 0) {
+    return Status::Error("Sending of internal database files is forbidden");
+  }
+  location.path_ = std::move(path);
+  TRY_RESULT(stat, stat(location.path_));
+  if (!stat.is_reg_) {
+    return Status::Error("File must be a regular file");
+  }
+  if (stat.size_ < 0) {
+    // TODO is it possible?
+    return Status::Error("File is too big");
+  }
+  if (stat.size_ == 0) {
+    return Status::Error("File must be non-empty");
+  }
+
+  if (size == 0) {
+    size = stat.size_;
+  }
+  if (location.mtime_nsec_ == 0) {
+    LOG(INFO) << "Set file \"" << location.path_ << "\" modification time to " << stat.mtime_nsec_;
+    location.mtime_nsec_ = stat.mtime_nsec_;
+  } else if (location.mtime_nsec_ != stat.mtime_nsec_) {
+    LOG(INFO) << "File \"" << location.path_ << "\" was nodified: old mtime = " << location.mtime_nsec_
+              << ", new mtime = " << stat.mtime_nsec_;
+    return Status::Error(PSLICE() << "File \"" << location.path_ << "\" was modified");
+  }
+  if ((location.file_type_ == FileType::Thumbnail || location.file_type_ == FileType::EncryptedThumbnail) &&
+      size >= MAX_THUMBNAIL_SIZE) {
+    return Status::Error(PSLICE() << "File \"" << location.path_ << "\" is too big for thumbnail "
+                                  << tag("size", format::as_size(size)));
+  }
+  if (size >= MAX_FILE_SIZE) {
+    return Status::Error(PSLICE() << "File \"" << location.path_ << "\" is too big "
+                                  << tag("size", format::as_size(size)));
+  }
+  return Status::OK();
+}
+
+static Status check_partial_local_location(const PartialLocalFileLocation &location) {
+  TRY_RESULT(stat, stat(location.path_));
+  if (!stat.is_reg_) {
+    if (stat.is_dir_) {
+      return Status::Error(PSLICE() << "Can't use directory \"" << location.path_ << "\" as a file path");
+    }
+    return Status::Error("File must be a regular file");
+  }
+  // can't check mtime. Hope nobody will mess with this file in our temporary dir.
+  return Status::OK();
+}
+
+Status FileManager::check_local_location(FileNodePtr node) {
+  Status status;
+  if (node->local_.type() == LocalFileLocation::Type::Full) {
+    status = check_local_location(node->local_.full(), node->size_);
+  } else if (node->local_.type() == LocalFileLocation::Type::Partial) {
+    status = check_partial_local_location(node->local_.partial());
+  }
+  if (status.is_error()) {
+    node->set_local_location(LocalFileLocation(), 0);
+    try_flush_node(node);
+  }
+  return status;
+}
+
+FileManager::FileIdInfo *FileManager::get_file_id_info(FileId file_id) {
+  CHECK(0 <= file_id.get() && file_id.get() < static_cast<int32>(file_id_info_.size()))
+      << file_id << " " << file_id_info_.size();
+  return &file_id_info_[file_id.get()];
+}
+
+FileId FileManager::dup_file_id(FileId file_id) {
+  int32 file_node_id;
+  auto *file_node = get_file_node_raw(file_id, &file_node_id);
+  if (!file_node) {
+    return FileId();
+  }
+  auto result = create_file_id(file_node_id, file_node);
+  LOG(INFO) << "Dup file " << file_id << " to " << result;
+  return result;
+}
+
+FileId FileManager::create_file_id(int32 file_node_id, FileNode *file_node) {
+  auto file_id = next_file_id();
+  get_file_id_info(file_id)->node_id_ = file_node_id;
+  file_node->file_ids_.push_back(file_id);
+  return file_id;
+}
+void FileManager::try_forget_file_id(FileId file_id) {
+  auto *info = get_file_id_info(file_id);
+  if (info->send_updates_flag_ || info->pin_flag_) {
+    return;
+  }
+  auto file_node = get_file_node(file_id);
+  if (file_node->main_file_id_ == file_id) {
+    return;
+  }
+
+  LOG(INFO) << "Forget file " << file_id;
+  auto it = std::find(file_node->file_ids_.begin(), file_node->file_ids_.end(), file_id);
+  CHECK(it != file_node->file_ids_.end());
+  file_node->file_ids_.erase(it);
+  *info = FileIdInfo();
+  empty_file_ids_.push_back(file_id.get());
+}
+
+FileId FileManager::register_empty(FileType type) {
+  return register_local(FullLocalFileLocation(type, "", 0), DialogId(), 0, false, true).ok();
+}
+
+void FileManager::on_file_unlink(const FullLocalFileLocation &location) {
+  auto it = local_location_to_file_id_.find(location);
+  if (it == local_location_to_file_id_.end()) {
+    return;
+  }
+  auto file_id = it->second;
+  auto file_node = get_sync_file_node(file_id);
+  CHECK(file_node);
+  file_node->set_local_location(LocalFileLocation(), 0);
+  try_flush_node_info(file_node);
+}
+
+Result<FileId> FileManager::register_local(FullLocalFileLocation location, DialogId owner_dialog_id, int64 size,
+                                           bool get_by_hash, bool force) {
+  // TODO: use get_by_hash
+  FileData data;
+  data.local_ = LocalFileLocation(std::move(location));
+  data.owner_dialog_id_ = owner_dialog_id;
+  data.size_ = size;
+  return register_file(std::move(data), FileLocationSource::None /*won't be used*/, "register_local", force);
+}
+
+FileId FileManager::register_remote(const FullRemoteFileLocation &location, FileLocationSource file_location_source,
+                                    DialogId owner_dialog_id, int64 size, int64 expected_size, string name) {
+  FileData data;
+  data.remote_ = RemoteFileLocation(location);
+  data.owner_dialog_id_ = owner_dialog_id;
+  data.size_ = size;
+  data.expected_size_ = expected_size;
+  data.remote_name_ = std::move(name);
+  return register_file(std::move(data), file_location_source, "register_remote", false).move_as_ok();
+}
+
+FileId FileManager::register_url(string url, FileType file_type, FileLocationSource file_location_source,
+                                 DialogId owner_dialog_id) {
+  auto file_id = register_generate(file_type, file_location_source, url, "#url#", owner_dialog_id, 0).ok();
+  auto file_node = get_file_node(file_id);
+  CHECK(file_node);
+  file_node->set_url(url);
+  return file_id;
+}
+
+Result<FileId> FileManager::register_generate(FileType file_type, FileLocationSource file_location_source,
+                                              string original_path, string conversion, DialogId owner_dialog_id,
+                                              int64 expected_size) {
+  FileData data;
+  data.generate_ = make_unique<FullGenerateFileLocation>(file_type, std::move(original_path), std::move(conversion));
+  data.owner_dialog_id_ = owner_dialog_id;
+  data.expected_size_ = expected_size;
+  return register_file(std::move(data), file_location_source, "register_generate", false);
+}
+
+Result<FileId> FileManager::register_file(FileData data, FileLocationSource file_location_source, const char *source,
+                                          bool force) {
+  bool has_remote = data.remote_.type() == RemoteFileLocation::Type::Full;
+  bool has_generate = data.generate_ != nullptr;
+  if (data.local_.type() == LocalFileLocation::Type::Full && !force) {
+    if (file_location_source == FileLocationSource::FromDb) {
+      PathView path_view(data.local_.full().path_);
+      if (path_view.is_relative()) {
+        data.local_.full().path_ = get_files_base_dir(data.local_.full().file_type_) + data.local_.full().path_;
+      }
+    }
+
+    auto status = check_local_location(data.local_.full(), data.size_);
+    if (status.is_error()) {
+      LOG(WARNING) << "Invalid local location: " << status << " from " << source;
+      data.local_ = LocalFileLocation();
+      if (data.remote_.type() == RemoteFileLocation::Type::Partial) {
+        data.remote_ = {};
+      }
+
+      if (!has_remote && !has_generate) {
+        return std::move(status);
+      }
+    }
+  }
+  bool has_local = data.local_.type() == LocalFileLocation::Type::Full;
+  bool has_location = has_local || has_remote || has_generate;
+  if (!has_location) {
+    return Status::Error("No location");
+  }
+
+  FileId file_id = next_file_id();
+
+  LOG(INFO) << "Register file data " << data << " as " << file_id << " from " << source;
+  // create FileNode
+  auto file_node_id = next_file_node_id();
+  auto &node = file_nodes_[file_node_id];
+  node = std::make_unique<FileNode>(std::move(data.local_), std::move(data.remote_), std::move(data.generate_),
+                                    data.size_, data.expected_size_, std::move(data.remote_name_), std::move(data.url_),
+                                    data.owner_dialog_id_, std::move(data.encryption_key_), file_id,
+                                    static_cast<int8>(has_remote));
+  node->remote_source_ = file_location_source;
+  node->pmc_id_ = data.pmc_id_;
+  get_file_id_info(file_id)->node_id_ = file_node_id;
+  node->file_ids_.push_back(file_id);
+
+  FileView file_view(get_file_node(file_id));
+
+  std::vector<FileId> to_merge;
+  auto register_location = [&](const auto &location, auto &mp) {
+    auto &other_id = mp[location];
+    if (other_id.empty()) {
+      other_id = file_id;
+      get_file_id_info(file_id)->pin_flag_ = true;
+      return true;
+    } else {
+      to_merge.push_back(other_id);
+      return false;
+    }
+  };
+  bool new_remote = false;
+  int32 remote_key = 0;
+  if (file_view.has_remote_location()) {
+    RemoteInfo info{file_view.remote_location(), file_id};
+    remote_key = remote_location_info_.add(info);
+    auto &stored_info = remote_location_info_.get(remote_key);
+    if (stored_info.file_id_ == file_id) {
+      get_file_id_info(file_id)->pin_flag_ = true;
+      new_remote = true;
+    } else {
+      to_merge.push_back(stored_info.file_id_);
+      if (stored_info.remote_ == file_view.remote_location() &&
+          stored_info.remote_.get_access_hash() != file_view.remote_location().get_access_hash() &&
+          file_location_source == FileLocationSource::FromServer) {
+        stored_info.remote_ = file_view.remote_location();
+      }
+    }
+  }
+  bool new_local = false;
+  if (file_view.has_local_location()) {
+    new_local = register_location(file_view.local_location(), local_location_to_file_id_);
+  }
+  bool new_generate = false;
+  if (file_view.has_generate_location()) {
+    new_generate = register_location(file_view.generate_location(), generate_location_to_file_id_);
+  }
+  std::sort(to_merge.begin(), to_merge.end());
+  to_merge.erase(std::unique(to_merge.begin(), to_merge.end()), to_merge.end());
+
+  int new_cnt = new_remote + new_local + new_generate;
+  if (data.pmc_id_ == 0 && file_db_ && new_cnt > 0) {
+    node->need_load_from_pmc_ = true;
+  }
+  bool no_sync_merge = to_merge.size() == 1 && new_cnt == 0;
+  for (auto id : to_merge) {
+    // may invalidate node
+    merge(file_id, id, no_sync_merge).ignore();
+  }
+
+  try_flush_node(get_file_node(file_id));
+  auto main_file_id = get_file_node(file_id)->main_file_id_;
+  try_forget_file_id(file_id);
+  return FileId(main_file_id.get(), remote_key);
+}
+
+// 0 -- choose x
+// 1 -- choose y
+// 2 -- choose any
+static int merge_choose(const LocalFileLocation &x, const LocalFileLocation &y) {
+  int32 x_type = static_cast<int32>(x.type());
+  int32 y_type = static_cast<int32>(y.type());
+  if (x_type != y_type) {
+    return x_type < y_type;
+  }
+  return 2;
+}
+
+static int merge_choose(const RemoteFileLocation &x, int8 x_source, const RemoteFileLocation &y, int8 y_source) {
+  int32 x_type = static_cast<int32>(x.type());
+  int32 y_type = static_cast<int32>(y.type());
+  if (x_type != y_type) {
+    return x_type < y_type;
+  }
+  // If access_hash changed use a newer one
+  if (x.type() == RemoteFileLocation::Type::Full) {
+    if (x.full().get_access_hash() != y.full().get_access_hash()) {
+      return x_source < y_source;
+    }
+  }
+  return 2;
+}
+static int merge_choose(const unique_ptr<FullGenerateFileLocation> &x, const unique_ptr<FullGenerateFileLocation> &y) {
+  int x_type = static_cast<int>(x != nullptr);
+  int y_type = static_cast<int>(y != nullptr);
+  if (x_type != y_type) {
+    return x_type < y_type;
+  }
+  return 2;
+}
+
+// -1 -- error
+static int merge_choose_size(int64 x, int64 y) {
+  if (x == 0) {
+    return 1;
+  }
+  if (y == 0) {
+    return 0;
+  }
+  if (x != y) {
+    return -1;
+  }
+  return 2;
+}
+static int merge_choose_expected_size(int64 x, int64 y) {
+  if (x == 0) {
+    return 1;
+  }
+  if (y == 0) {
+    return 0;
+  }
+  return 2;
+}
+
+static int merge_choose_name(Slice x, Slice y) {
+  if (x.empty() != y.empty()) {
+    return x.empty() > y.empty();
+  }
+  return 2;
+}
+
+static int merge_choose_owner(DialogId x, DialogId y) {
+  if (x.is_valid() != y.is_valid()) {
+    return x.is_valid() < y.is_valid();
+  }
+  return 2;
+}
+
+static int merge_choose_main_file_id(FileId a, int8 a_priority, FileId b, int8 b_priority) {
+  if (a_priority != b_priority) {
+    return a_priority < b_priority;
+  }
+  return a.get() > b.get();
+}
+
+static int merge_choose_encryption_key(const FileEncryptionKey &a, const FileEncryptionKey &b) {
+  if (a.empty() != b.empty()) {
+    return a.empty() > b.empty();
+  }
+  if (a.key_iv_ != b.key_iv_) {
+    return -1;
+  }
+  return 2;
+}
+
+void FileManager::cancel_download(FileNodePtr node) {
+  if (node->download_id_ == 0) {
+    return;
+  }
+  send_closure(file_load_manager_, &FileLoadManager::cancel, node->download_id_);
+  node->download_id_ = 0;
+  node->is_download_started_ = false;
+  node->set_download_priority(0);
+}
+
+void FileManager::cancel_upload(FileNodePtr node) {
+  if (node->upload_id_ == 0) {
+    return;
+  }
+  send_closure(file_load_manager_, &FileLoadManager::cancel, node->upload_id_);
+  node->upload_id_ = 0;
+  node->set_upload_priority(0);
+}
+
+void FileManager::cancel_generate(FileNodePtr node) {
+  if (node->generate_id_ == 0) {
+    return;
+  }
+  send_closure(file_generate_manager_, &FileGenerateManager::cancel, node->generate_id_);
+  node->generate_id_ = 0;
+  node->generate_was_update_ = false;
+  node->set_generate_priority(0, 0);
+}
+
+Result<FileId> FileManager::merge(FileId x_file_id, FileId y_file_id, bool no_sync) {
+  LOG(INFO) << x_file_id << " VS " << y_file_id;
+
+  if (!x_file_id.is_valid()) {
+    return Status::Error("First file_id is invalid");
+  }
+  FileNodePtr x_node = no_sync ? get_file_node(x_file_id) : get_sync_file_node(x_file_id);
+  if (!x_node) {
+    return Status::Error(PSLICE() << "Can't merge files. First id is invalid: " << x_file_id << " and " << y_file_id);
+  }
+
+  if (!y_file_id.is_valid()) {
+    return x_node->main_file_id_;
+  }
+  FileNodePtr y_node = get_file_node(y_file_id);
+  if (!y_node) {
+    return Status::Error(PSLICE() << "Can't merge files. Second id is invalid: " << x_file_id << " and " << y_file_id);
+  }
+
+  if (x_file_id == x_node->upload_pause_) {
+    x_node->upload_pause_ = FileId();
+  }
+  if (x_node.get() == y_node.get()) {
+    return x_node->main_file_id_;
+  }
+  if (y_file_id == y_node->upload_pause_) {
+    y_node->upload_pause_ = FileId();
+  }
+
+  if (x_node->remote_.type() == RemoteFileLocation::Type::Full &&
+      y_node->remote_.type() == RemoteFileLocation::Type::Full &&
+      x_node->remote_.full().get_dc_id() != y_node->remote_.full().get_dc_id()) {
+    LOG(ERROR) << "File remote location was changed from " << y_node->remote_.full() << " to "
+               << x_node->remote_.full();
+  }
+
+  FileNodePtr nodes[] = {x_node, y_node, x_node};
+  FileNodeId node_ids[] = {get_file_id_info(x_file_id)->node_id_, get_file_id_info(y_file_id)->node_id_};
+
+  int local_i = merge_choose(x_node->local_, y_node->local_);
+  int remote_i = merge_choose(x_node->remote_, static_cast<int8>(x_node->remote_source_), y_node->remote_,
+                              static_cast<int8>(y_node->remote_source_));
+  int generate_i = merge_choose(x_node->generate_, y_node->generate_);
+  int size_i = merge_choose_size(x_node->size_, y_node->size_);
+  int expected_size_i = merge_choose_expected_size(x_node->expected_size_, y_node->expected_size_);
+  int remote_name_i = merge_choose_name(x_node->remote_name_, y_node->remote_name_);
+  int url_i = merge_choose_name(x_node->url_, y_node->url_);
+  int owner_i = merge_choose_owner(x_node->owner_dialog_id_, y_node->owner_dialog_id_);
+  int encryption_key_i = merge_choose_encryption_key(x_node->encryption_key_, y_node->encryption_key_);
+  int main_file_id_i = merge_choose_main_file_id(x_node->main_file_id_, x_node->main_file_id_priority_,
+                                                 y_node->main_file_id_, y_node->main_file_id_priority_);
+
+  if (size_i == -1) {
+    return Status::Error(PSLICE() << "Can't merge files. Different size: " << x_node->size_ << " and "
+                                  << y_node->size_);
+  }
+  if (encryption_key_i == -1) {
+    if (nodes[remote_i]->remote_.type() == RemoteFileLocation::Type::Full &&
+        nodes[local_i]->local_.type() != LocalFileLocation::Type::Partial) {
+      //???
+      LOG(ERROR) << "Different encryption key in files, but go Choose same key as remote location";
+      encryption_key_i = remote_i;
+    } else {
+      return Status::Error("Can't merge files. Different encryption keys");
+    }
+  }
+
+  int node_i = std::make_tuple(y_node->pmc_id_, y_node->file_ids_.size(), main_file_id_i == 1) >
+               std::make_tuple(x_node->pmc_id_, x_node->file_ids_.size(), main_file_id_i == 0);
+
+  auto other_node_i = 1 - node_i;
+  FileNodePtr node = nodes[node_i];
+  FileNodePtr other_node = nodes[other_node_i];
+  auto file_view = FileView(node);
+
+  LOG(INFO) << "x_node->pmc_id_ = " << x_node->pmc_id_ << ", y_node->pmc_id_ = " << y_node->pmc_id_
+            << ", x_node_size = " << x_node->file_ids_.size() << ", y_node_size = " << y_node->file_ids_.size()
+            << ", node_i = " << node_i << ", local_i = " << local_i << ", remote_i = " << remote_i
+            << ", generate_i = " << generate_i << ", size_i = " << size_i << ", remote_name_i = " << remote_name_i
+            << ", url_i = " << url_i << ", owner_i = " << owner_i << ", encryption_key_i = " << encryption_key_i
+            << ", main_file_id_i = " << main_file_id_i;
+  if (local_i == other_node_i) {
+    cancel_download(node);
+    node->set_local_location(other_node->local_, other_node->local_ready_size_);
+    node->download_id_ = other_node->download_id_;
+    node->is_download_started_ |= other_node->is_download_started_;
+    node->set_download_priority(other_node->download_priority_);
+    other_node->download_id_ = 0;
+    other_node->is_download_started_ = false;
+    other_node->download_priority_ = 0;
+
+    //cancel_generate(node);
+    //node->set_generate_location(std::move(other_node->generate_));
+    //node->generate_id_ = other_node->generate_id_;
+    //node->set_generate_priority(other_node->generate_download_priority_, other_node->generate_upload_priority_);
+    //other_node->generate_id_ = 0;
+    //other_node->generate_was_update_ = false;
+    //other_node->generate_priority_ = 0;
+    //other_node->generate_download_priority_ = 0;
+    //other_node->generate_upload_priority_ = 0;
+  } else {
+    cancel_download(other_node);
+    //cancel_generate(other_node);
+  }
+
+  if (remote_i == other_node_i) {
+    cancel_upload(node);
+    node->set_remote_location(other_node->remote_, other_node->remote_source_, other_node->remote_ready_size_);
+    node->upload_id_ = other_node->upload_id_;
+    node->set_upload_priority(other_node->upload_priority_);
+    node->upload_pause_ = other_node->upload_pause_;
+    other_node->upload_id_ = 0;
+    other_node->upload_priority_ = 0;
+    other_node->upload_pause_ = FileId();
+  } else {
+    cancel_upload(other_node);
+  }
+
+  if (generate_i == other_node_i) {
+    cancel_generate(node);
+    node->set_generate_location(std::move(other_node->generate_));
+    node->generate_id_ = other_node->generate_id_;
+    node->set_generate_priority(other_node->generate_download_priority_, other_node->generate_upload_priority_);
+    other_node->generate_id_ = 0;
+    other_node->generate_priority_ = 0;
+    other_node->generate_download_priority_ = 0;
+    other_node->generate_upload_priority_ = 0;
+  } else {
+    cancel_generate(other_node);
+  }
+
+  if (size_i == other_node_i) {
+    node->set_size(other_node->size_);
+  }
+
+  if (expected_size_i == other_node_i) {
+    node->set_expected_size(other_node->expected_size_);
+  }
+
+  if (remote_name_i == other_node_i) {
+    node->set_remote_name(other_node->remote_name_);
+  }
+
+  if (url_i == other_node_i) {
+    node->set_url(other_node->url_);
+  }
+
+  if (owner_i == other_node_i) {
+    node->set_owner_dialog_id(other_node->owner_dialog_id_);
+  }
+
+  if (encryption_key_i == other_node_i) {
+    node->set_encryption_key(other_node->encryption_key_);
+    nodes[node_i]->set_encryption_key(nodes[encryption_key_i]->encryption_key_);
+  }
+  node->need_load_from_pmc_ |= other_node->need_load_from_pmc_;
+  node->can_search_locally_ &= other_node->can_search_locally_;
+
+  if (main_file_id_i == other_node_i) {
+    node->main_file_id_ = other_node->main_file_id_;
+    node->main_file_id_priority_ = other_node->main_file_id_priority_;
+  }
+
+  bool send_updates_flag = false;
+  auto other_pmc_id = other_node->pmc_id_;
+  node->file_ids_.insert(node->file_ids_.end(), other_node->file_ids_.begin(), other_node->file_ids_.end());
+
+  for (auto file_id : other_node->file_ids_) {
+    auto file_id_info = get_file_id_info(file_id);
+    CHECK(file_id_info->node_id_ == node_ids[other_node_i])
+        << node_ids[node_i] << " " << node_ids[other_node_i] << " " << file_id << " " << file_id_info->node_id_;
+    file_id_info->node_id_ = node_ids[node_i];
+    send_updates_flag |= file_id_info->send_updates_flag_;
+  }
+  other_node = {};
+
+  if (send_updates_flag) {
+    // node might not changed, but other_node might changed, so we need to send update anyway
+    VLOG(update_file) << "File " << node->main_file_id_ << " has been merged";
+    node->on_info_changed();
+  }
+
+  // Check is some download/upload queries are ready
+  for (auto file_id : vector<FileId>(node->file_ids_)) {
+    auto *info = get_file_id_info(file_id);
+    if (info->download_priority_ != 0 && file_view.has_local_location()) {
+      info->download_priority_ = 0;
+      if (info->download_callback_) {
+        info->download_callback_->on_download_ok(file_id);
+        info->download_callback_.reset();
+      }
+    }
+    if (info->upload_priority_ != 0 && file_view.has_remote_location()) {
+      info->upload_priority_ = 0;
+      if (info->upload_callback_) {
+        info->upload_callback_->on_upload_ok(file_id, nullptr);
+        info->upload_callback_.reset();
+      }
+    }
+  }
+
+  file_nodes_[node_ids[other_node_i]] = nullptr;
+
+  run_generate(node);
+  run_download(node);
+  run_upload(node, {});
+
+  if (other_pmc_id != 0) {
+    // node might not changed, but we need to merge nodes in pmc anyway
+    node->on_pmc_changed();
+  }
+  try_flush_node(node, node_i != remote_i, node_i != local_i, node_i != generate_i, other_pmc_id);
+
+  return node->main_file_id_;
+}
+
+void FileManager::try_flush_node(FileNodePtr node, bool new_remote, bool new_local, bool new_generate,
+                                 FileDbId other_pmc_id) {
+  if (node->need_pmc_flush()) {
+    if (file_db_) {
+      load_from_pmc(node, true, true, true);
+      flush_to_pmc(node, new_remote, new_local, new_generate);
+      if (other_pmc_id != 0 && node->pmc_id_ != other_pmc_id) {
+        file_db_->set_file_data_ref(other_pmc_id, node->pmc_id_);
+      }
+    }
+    node->on_pmc_flushed();
+  }
+
+  try_flush_node_info(node);
+}
+
+void FileManager::try_flush_node_info(FileNodePtr node) {
+  if (node->need_info_flush()) {
+    for (auto file_id : vector<FileId>(node->file_ids_)) {
+      auto *info = get_file_id_info(file_id);
+      if (info->send_updates_flag_) {
+        VLOG(update_file) << "Send UpdateFile about file " << file_id;
+        context_->on_file_updated(file_id);
+      }
+    }
+    node->on_info_flushed();
+  }
+}
+
+void FileManager::clear_from_pmc(FileNodePtr node) {
+  if (!file_db_) {
+    return;
+  }
+  if (node->pmc_id_ == 0) {
+    return;
+  }
+
+  LOG(INFO) << "Delete files " << format::as_array(node->file_ids_) << " from pmc";
+  FileData data;
+  auto file_view = FileView(node);
+  if (file_view.has_local_location()) {
+    data.local_ = node->local_;
+  }
+  if (file_view.has_remote_location()) {
+    data.remote_ = node->remote_;
+  }
+  if (file_view.has_generate_location()) {
+    data.generate_ = std::make_unique<FullGenerateFileLocation>(*node->generate_);
+  }
+  file_db_->clear_file_data(node->pmc_id_, data);
+  node->pmc_id_ = 0;
+}
+
+void FileManager::flush_to_pmc(FileNodePtr node, bool new_remote, bool new_local, bool new_generate) {
+  if (!file_db_) {
+    return;
+  }
+  FileView view(node);
+  bool create_flag = false;
+  if (node->pmc_id_ == 0) {
+    create_flag = true;
+    node->pmc_id_ = file_db_->create_pmc_id();
+  }
+
+  FileData data;
+  data.pmc_id_ = node->pmc_id_;
+  data.local_ = node->local_;
+  if (data.local_.type() == LocalFileLocation::Type::Full) {
+    prepare_path_for_pmc(data.local_.full().file_type_, data.local_.full().path_);
+  }
+  data.remote_ = node->remote_;
+  if (node->generate_ != nullptr && !begins_with(node->generate_->conversion_, "#file_id#")) {
+    data.generate_ = std::make_unique<FullGenerateFileLocation>(*node->generate_);
+  }
+
+  // TODO: not needed when GenerateLocation has constant convertion
+  if (data.remote_.type() != RemoteFileLocation::Type::Full && data.local_.type() != LocalFileLocation::Type::Full) {
+    data.local_ = LocalFileLocation();
+    data.remote_ = RemoteFileLocation();
+  }
+
+  data.size_ = node->size_;
+  data.expected_size_ = node->expected_size_;
+  data.remote_name_ = node->remote_name_;
+  data.encryption_key_ = node->encryption_key_;
+  data.url_ = node->url_;
+  data.owner_dialog_id_ = node->owner_dialog_id_;
+
+  file_db_->set_file_data(node->pmc_id_, data, (create_flag || new_remote), (create_flag || new_local),
+                          (create_flag || new_generate));
+}
+
+FileNode *FileManager::get_file_node_raw(FileId file_id, FileNodeId *file_node_id) {
+  if (file_id.get() <= 0 || file_id.get() >= static_cast<int32>(file_id_info_.size())) {
+    return nullptr;
+  }
+  FileNodeId node_id = file_id_info_[file_id.get()].node_id_;
+  if (node_id == 0) {
+    return nullptr;
+  }
+  if (file_node_id != nullptr) {
+    *file_node_id = node_id;
+  }
+  return file_nodes_[node_id].get();
+}
+
+FileNodePtr FileManager::get_sync_file_node(FileId file_id) {
+  auto file_node = get_file_node(file_id);
+  if (!file_node) {
+    return {};
+  }
+  load_from_pmc(file_node, true, true, true);
+  return file_node;
+}
+
+void FileManager::load_from_pmc(FileNodePtr node, bool new_remote, bool new_local, bool new_generate) {
+  if (!node->need_load_from_pmc_) {
+    return;
+  }
+  auto file_id = node->main_file_id_;
+  node->need_load_from_pmc_ = false;
+  if (!file_db_) {
+    return;
+  }
+  auto file_view = get_file_view(file_id);
+
+  FullRemoteFileLocation remote;
+  FullLocalFileLocation local;
+  FullGenerateFileLocation generate;
+  new_remote &= file_view.has_remote_location();
+  if (new_remote) {
+    remote = file_view.remote_location();
+  }
+  new_local &= file_view.has_local_location();
+  if (new_local) {
+    local = get_file_view(file_id).local_location();
+    prepare_path_for_pmc(local.file_type_, local.path_);
+  }
+  new_generate &= file_view.has_generate_location();
+  if (new_generate) {
+    generate = file_view.generate_location();
+  }
+
+  LOG(INFO) << "Load from pmc " << file_id << "/" << file_view.file_id() << ", new_remote = " << new_remote
+            << ", new_local = " << new_local << ", new_generate = " << new_generate;
+  auto load = [&](auto location) {
+    TRY_RESULT(file_data, file_db_->get_file_data_sync(location));
+    TRY_RESULT(new_file_id, register_file(std::move(file_data), FileLocationSource::FromDb, "load_from_pmc", false));
+    TRY_RESULT(main_file_id, merge(file_id, new_file_id));
+    file_id = main_file_id;
+    return Status::OK();
+  };
+  if (new_remote) {
+    load(remote);
+  }
+  if (new_local) {
+    load(local);
+  }
+  if (new_generate) {
+    load(generate);
+  }
+  return;
+}
+
+bool FileManager::set_encryption_key(FileId file_id, FileEncryptionKey key) {
+  auto node = get_sync_file_node(file_id);
+  if (!node) {
+    return false;
+  }
+  auto view = FileView(node);
+  if (view.has_local_location() && view.has_remote_location()) {
+    return false;
+  }
+  if (!node->encryption_key_.empty()) {
+    return false;
+  }
+  node->set_encryption_key(std::move(key));
+  try_flush_node(node);
+  return true;
+}
+
+bool FileManager::set_content(FileId file_id, BufferSlice bytes) {
+  auto node = get_sync_file_node(file_id);
+  if (!node) {
+    return false;
+  }
+
+  if (node->local_.type() == LocalFileLocation::Type::Full) {
+    // There was no download so we don't need an update
+    return true;
+  }
+
+  if (node->download_priority_ == FROM_BYTES_PRIORITY) {
+    return true;
+  }
+
+  cancel_download(node);
+
+  auto *file_info = get_file_id_info(file_id);
+  file_info->download_priority_ = FROM_BYTES_PRIORITY;
+
+  node->set_download_priority(FROM_BYTES_PRIORITY);
+
+  QueryId id = queries_container_.create(Query{file_id, Query::SetContent});
+  node->download_id_ = id;
+  node->is_download_started_ = true;
+  send_closure(file_load_manager_, &FileLoadManager::from_bytes, id, node->remote_.full().file_type_, std::move(bytes),
+               node->suggested_name());
+  return true;
+}
+
+void FileManager::get_content(FileId file_id, Promise<BufferSlice> promise) {
+  auto node = get_sync_file_node(file_id);
+  if (!node) {
+    return promise.set_error(Status::Error("Unknown file_id"));
+  }
+  auto status = check_local_location(node);
+  status.ignore();
+
+  auto file_view = FileView(node);
+  if (!file_view.has_local_location()) {
+    return promise.set_error(Status::Error("No local location"));
+  }
+
+  send_closure(file_load_manager_, &FileLoadManager::get_content, node->local_.full(), std::move(promise));
+}
+
+void FileManager::delete_file(FileId file_id, Promise<Unit> promise, const char *source) {
+  LOG(INFO) << "Trying to delete file " << file_id << " from " << source;
+  auto node = get_sync_file_node(file_id);
+  if (!node) {
+    return promise.set_value(Unit());
+  }
+
+  auto file_view = FileView(node);
+
+  // TODO: review delete condition
+  if (file_view.has_local_location()) {
+    if (begins_with(file_view.local_location().path_, get_files_dir(file_view.get_type()))) {
+      LOG(INFO) << "Unlink file " << file_id << " at " << file_view.local_location().path_;
+      clear_from_pmc(node);
+
+      unlink(file_view.local_location().path_).ignore();
+      context_->on_new_file(-file_view.size());
+      node->set_local_location(LocalFileLocation(), 0);
+      try_flush_node(node);
+    }
+  } else {
+    if (file_view.get_type() == FileType::Encrypted) {
+      clear_from_pmc(node);
+    }
+    if (node->local_.type() == LocalFileLocation::Type::Partial) {
+      LOG(INFO) << "Unlink partial file " << file_id << " at " << node->local_.partial().path_;
+      unlink(node->local_.partial().path_).ignore();
+      node->set_local_location(LocalFileLocation(), 0);
+      try_flush_node(node);
+    }
+  }
+
+  promise.set_value(Unit());
+}
+
+void FileManager::download(FileId file_id, std::shared_ptr<DownloadCallback> callback, int32 new_priority) {
+  auto node = get_sync_file_node(file_id);
+  if (!node) {
+    if (callback) {
+      callback->on_download_error(file_id, Status::Error("File not found"));
+    }
+    return;
+  }
+
+  if (node->local_.type() == LocalFileLocation::Type::Full) {
+    auto status = check_local_location(node);
+    if (status.is_error()) {
+      LOG(WARNING) << "Need to redownload file " << file_id << ": " << status.error();
+    } else {
+      if (callback) {
+        callback->on_download_ok(file_id);
+      }
+      return;
+    }
+  } else if (node->local_.type() == LocalFileLocation::Type::Partial) {
+    auto status = check_local_location(node);
+    if (status.is_error()) {
+      LOG(WARNING) << "Need to download file " << file_id << " from beginning: " << status.error();
+    }
+  }
+
+  FileView file_view(node);
+  if (!file_view.can_download_from_server() && !file_view.can_generate()) {
+    if (callback) {
+      callback->on_download_error(file_id, Status::Error("Can't download or generate file"));
+    }
+    return;
+  }
+
+  if (new_priority == -1) {
+    if (node->is_download_started_) {
+      return;
+    }
+    new_priority = 0;
+  }
+
+  auto *file_info = get_file_id_info(file_id);
+  CHECK(new_priority == 0 || callback);
+  file_info->download_priority_ = narrow_cast<int8>(new_priority);
+  file_info->download_callback_ = std::move(callback);
+  // TODO: send current progress?
+
+  run_generate(node);
+  run_download(node);
+
+  try_flush_node(node);
+}
+
+void FileManager::run_download(FileNodePtr node) {
+  if (node->need_load_from_pmc_) {
+    return;
+  }
+  if (node->generate_id_) {
+    return;
+  }
+  auto file_view = FileView(node);
+  if (!file_view.can_download_from_server()) {
+    return;
+  }
+  int8 priority = 0;
+  for (auto id : node->file_ids_) {
+    auto *info = get_file_id_info(id);
+    if (info->download_priority_ > priority) {
+      priority = info->download_priority_;
+    }
+  }
+
+  auto old_priority = node->download_priority_;
+  node->set_download_priority(priority);
+
+  if (priority == 0) {
+    if (old_priority != 0) {
+      cancel_download(node);
+    }
+    return;
+  }
+
+  if (old_priority != 0) {
+    CHECK(node->download_id_ != 0);
+    send_closure(file_load_manager_, &FileLoadManager::update_priority, node->download_id_, priority);
+    return;
+  }
+
+  CHECK(node->download_id_ == 0);
+  CHECK(!node->file_ids_.empty());
+  auto file_id = node->file_ids_.back();
+  QueryId id = queries_container_.create(Query{file_id, Query::Download});
+  node->download_id_ = id;
+  node->is_download_started_ = false;
+  send_closure(file_load_manager_, &FileLoadManager::download, id, node->remote_.full(), node->local_, node->size_,
+               node->suggested_name(), node->encryption_key_, node->can_search_locally_, priority);
+}
+
+void FileManager::resume_upload(FileId file_id, std::vector<int> bad_parts, std::shared_ptr<UploadCallback> callback,
+                                int32 new_priority, uint64 upload_order) {
+  LOG(INFO) << "Resume upload of file " << file_id << " with priority " << new_priority;
+
+  auto node = get_sync_file_node(file_id);
+  if (!node) {
+    if (callback) {
+      callback->on_upload_error(file_id, Status::Error("Wrong file id to upload"));
+    }
+    return;
+  }
+  if (node->upload_pause_ == file_id) {
+    node->upload_pause_ = FileId();
+  }
+  FileView file_view(node);
+  if (file_view.has_remote_location() && file_view.get_type() != FileType::Thumbnail &&
+      file_view.get_type() != FileType::EncryptedThumbnail) {
+    if (callback) {
+      callback->on_upload_ok(file_id, nullptr);
+    }
+    return;
+  }
+
+  if (file_view.has_local_location()) {
+    auto status = check_local_location(node);
+    if (status.is_error()) {
+      LOG(INFO) << "Full local location of file " << file_id << " for upload is invalid: " << status;
+    }
+  }
+
+  if (!file_view.has_local_location() && !file_view.has_generate_location()) {
+    if (callback) {
+      callback->on_upload_error(file_id, Status::Error("Need full local (or generate) location for upload"));
+    }
+    return;
+  }
+
+  auto *file_info = get_file_id_info(file_id);
+  CHECK(new_priority == 0 || callback);
+  file_info->upload_order_ = upload_order;
+  file_info->upload_priority_ = narrow_cast<int8>(new_priority);
+  file_info->upload_callback_ = std::move(callback);
+  // TODO: send current progress?
+
+  run_generate(node);
+  run_upload(node, std::move(bad_parts));
+  try_flush_node(node);
+}
+
+bool FileManager::delete_partial_remote_location(FileId file_id) {
+  auto node = get_sync_file_node(file_id);
+  if (!node) {
+    LOG(INFO) << "Wrong file id " << file_id;
+    return false;
+  }
+  if (node->upload_pause_ == file_id) {
+    node->upload_pause_ = FileId();
+  }
+  if (node->remote_.type() == RemoteFileLocation::Type::Full) {
+    LOG(INFO) << "File " << file_id << " is already uploaded";
+    return true;
+  }
+
+  node->set_remote_location(RemoteFileLocation(), FileLocationSource::None, 0);
+  auto *file_info = get_file_id_info(file_id);
+  file_info->upload_priority_ = 0;
+
+  if (node->local_.type() != LocalFileLocation::Type::Full) {
+    LOG(INFO) << "Need full local location to upload file " << file_id;
+    return false;
+  }
+
+  auto status = check_local_location(node);
+  if (status.is_error()) {
+    LOG(INFO) << "Need full local location to upload file " << file_id << ": " << status;
+    return false;
+  }
+
+  run_upload(node, std::vector<int>());
+  try_flush_node(node);
+  return true;
+}
+
+void FileManager::external_file_generate_progress(int64 id, int32 expected_size, int32 local_prefix_size,
+                                                  Promise<> promise) {
+  send_closure(file_generate_manager_, &FileGenerateManager::external_file_generate_progress, id, expected_size,
+               local_prefix_size, std::move(promise));
+}
+void FileManager::external_file_generate_finish(int64 id, Status status, Promise<> promise) {
+  send_closure(file_generate_manager_, &FileGenerateManager::external_file_generate_finish, id, std::move(status),
+               std::move(promise));
+}
+
+void FileManager::run_generate(FileNodePtr node) {
+  if (node->need_load_from_pmc_) {
+    return;
+  }
+  FileView file_view(node);
+  if (file_view.has_local_location() || file_view.can_download_from_server() || !file_view.can_generate()) {
+    return;
+  }
+
+  int8 download_priority = 0;
+  int8 upload_priority = 0;
+  FileId file_id = node->main_file_id_;
+  for (auto id : node->file_ids_) {
+    auto *info = get_file_id_info(id);
+    if (info->download_priority_ > download_priority) {
+      download_priority = info->download_priority_;
+      if (download_priority > upload_priority) {
+        file_id = id;
+      }
+    }
+    if (info->upload_priority_ > upload_priority) {
+      upload_priority = info->upload_priority_;
+      if (upload_priority > download_priority) {
+        file_id = id;
+      }
+    }
+  }
+
+  auto old_priority = node->generate_priority_;
+  node->set_generate_priority(download_priority, upload_priority);
+
+  if (node->generate_priority_ == 0) {
+    if (old_priority != 0) {
+      LOG(INFO) << "Cancel file " << file_id << " generation";
+      cancel_generate(node);
+    }
+    return;
+  }
+
+  if (old_priority != 0) {
+    LOG(INFO) << "TODO: change file " << file_id << " generation priority";
+    return;
+  }
+
+  QueryId id = queries_container_.create(Query{file_id, Query::Generate});
+  node->generate_id_ = id;
+  send_closure(file_generate_manager_, &FileGenerateManager::generate_file, id, *node->generate_, node->local_,
+               node->suggested_name(), [file_manager = this, id] {
+                 class Callback : public FileGenerateCallback {
+                   ActorId<FileManager> actor_;
+                   uint64 query_id_;
+
+                  public:
+                   Callback(ActorId<FileManager> actor, QueryId id) : actor_(std::move(actor)), query_id_(id) {
+                   }
+                   void on_partial_generate(const PartialLocalFileLocation &partial_local,
+                                            int32 expected_size) override {
+                     send_closure(actor_, &FileManager::on_partial_generate, query_id_, partial_local, expected_size);
+                   }
+                   void on_ok(const FullLocalFileLocation &local) override {
+                     send_closure(actor_, &FileManager::on_generate_ok, query_id_, local);
+                   }
+                   void on_error(Status error) override {
+                     send_closure(actor_, &FileManager::on_error, query_id_, std::move(error));
+                   }
+                 };
+                 return std::make_unique<Callback>(file_manager->actor_id(file_manager), id);
+               }());
+
+  LOG(INFO) << "File " << file_id << " generate request has sent to FileGenerateManager";
+}
+
+void FileManager::run_upload(FileNodePtr node, std::vector<int> bad_parts) {
+  if (node->need_load_from_pmc_) {
+    return;
+  }
+  if (node->upload_pause_.is_valid()) {
+    return;
+  }
+  FileView file_view(node);
+  if (!file_view.has_local_location()) {
+    if (node->get_by_hash_ || node->generate_id_ == 0 || !node->generate_was_update_) {
+      return;
+    }
+  }
+  int8 priority = 0;
+  FileId file_id = node->main_file_id_;
+  for (auto id : node->file_ids_) {
+    auto *info = get_file_id_info(id);
+    if (info->upload_priority_ > priority) {
+      priority = info->upload_priority_;
+      file_id = id;
+    }
+  }
+
+  auto old_priority = node->upload_priority_;
+  node->set_upload_priority(priority);
+
+  if (priority == 0) {
+    if (old_priority != 0) {
+      LOG(INFO) << "Cancel file " << file_id << " uploading";
+      cancel_upload(node);
+    }
+    return;
+  }
+
+  // create encryption key if necessary
+  if (((file_view.has_generate_location() && file_view.generate_location().file_type_ == FileType::Encrypted) ||
+       (file_view.has_local_location() && file_view.local_location().file_type_ == FileType::Encrypted)) &&
+      file_view.encryption_key().empty()) {
+    CHECK(!node->file_ids_.empty());
+    bool success = set_encryption_key(node->file_ids_[0], FileEncryptionKey::create());
+    LOG_IF(FATAL, !success) << "Failed to set encryption key for file " << file_id;
+  }
+
+  if (old_priority != 0) {
+    LOG(INFO) << "File " << file_id << " is already uploading";
+    CHECK(node->upload_id_ != 0);
+    send_closure(file_load_manager_, &FileLoadManager::update_priority, node->upload_id_, narrow_cast<int8>(-priority));
+    return;
+  }
+
+  CHECK(node->upload_id_ == 0);
+  if (node->remote_.type() != RemoteFileLocation::Type::Partial && node->get_by_hash_) {
+    QueryId id = queries_container_.create(Query{file_id, Query::UploadByHash});
+    node->upload_id_ = id;
+
+    send_closure(file_load_manager_, &FileLoadManager::upload_by_hash, id, node->local_.full(), node->size_,
+                 narrow_cast<int8>(-priority));
+    return;
+  }
+
+  QueryId id = queries_container_.create(Query{file_id, Query::Upload});
+  node->upload_id_ = id;
+  send_closure(file_load_manager_, &FileLoadManager::upload, id, node->local_, node->remote_, node->size_,
+               node->encryption_key_, narrow_cast<int8>(bad_parts.empty() ? -priority : priority),
+               std::move(bad_parts));
+
+  LOG(INFO) << "File " << file_id << " upload request has sent to FileLoadManager";
+}
+
+void FileManager::upload(FileId file_id, std::shared_ptr<UploadCallback> callback, int32 new_priority,
+                         uint64 upload_order) {
+  return resume_upload(file_id, std::vector<int>(), std::move(callback), new_priority, upload_order);
+}
+
+// is't quite stupid, yep
+// 0x00 <count of zeroes>
+static string zero_decode(Slice s) {
+  string res;
+  for (size_t n = s.size(), i = 0; i < n; i++) {
+    if (i + 1 < n && s[i] == 0) {
+      res.append(static_cast<unsigned char>(s[i + 1]), 0);
+      i++;
+      continue;
+    }
+    res.push_back(s[i]);
+  }
+  return res;
+}
+
+static string zero_encode(Slice s) {
+  string res;
+  for (size_t n = s.size(), i = 0; i < n; i++) {
+    res.push_back(s[i]);
+    if (s[i] == 0) {
+      unsigned char cnt = 1;
+      while (cnt < 250 && i + cnt < n && s[i + cnt] == 0) {
+        cnt++;
+      }
+      res.push_back(cnt);
+      i += cnt - 1;
+    }
+  }
+  return res;
+}
+
+static bool is_document_type(FileType type) {
+  return type == FileType::Document || type == FileType::Sticker || type == FileType::Audio ||
+         type == FileType::Animation;
+}
+
+string FileManager::get_persistent_id(const FullRemoteFileLocation &location) {
+  auto binary = serialize(location);
+
+  binary = zero_encode(binary);
+  binary.push_back(PERSISTENT_ID_VERSION);
+  return base64url_encode(binary);
+}
+
+Result<string> FileManager::to_persistent_id(FileId file_id) {
+  auto view = get_file_view(file_id);
+  if (view.empty()) {
+    return Status::Error(10, "Unknown file id");
+  }
+  if (!view.has_remote_location()) {
+    return Status::Error(10, "File has no persistent id");
+  }
+  return get_persistent_id(view.remote_location());
+}
+
+Result<FileId> FileManager::from_persistent_id(CSlice persistent_id, FileType file_type) {
+  if (persistent_id.find('.') != string::npos) {
+    string input_url = persistent_id.str();  // TODO do not copy persistent_id
+    TRY_RESULT(http_url, parse_url(input_url));
+    auto url = http_url.get_url();
+    if (!clean_input_string(url)) {
+      return Status::Error(400, "URL must be in UTF-8");
+    }
+    return register_url(std::move(url), file_type, FileLocationSource::FromUser, DialogId());
+  }
+
+  auto r_binary = base64url_decode(persistent_id);
+  if (r_binary.is_error()) {
+    return Status::Error(10, "Wrong remote file id specified: " + r_binary.error().message().str());
+  }
+  auto binary = r_binary.move_as_ok();
+  if (binary.empty()) {
+    return Status::Error(10, "Remote file id can't be empty");
+  }
+  if (binary.back() != PERSISTENT_ID_VERSION) {
+    return Status::Error(10, "Wrong remote file id specified: can't unserialize it. Wrong last symbol");
+  }
+  binary.pop_back();
+  binary = zero_decode(binary);
+  FullRemoteFileLocation remote_location;
+  auto status = unserialize(remote_location, binary);
+  if (status.is_error()) {
+    return Status::Error(10, "Wrong remote file id specified: can't unserialize it");
+  }
+  auto &real_file_type = remote_location.file_type_;
+  if (is_document_type(real_file_type) && is_document_type(file_type)) {
+    real_file_type = file_type;
+  } else if (real_file_type != file_type && file_type != FileType::Temp) {
+    return Status::Error(10, "Type of file mismatch");
+  }
+  FileData data;
+  data.remote_ = RemoteFileLocation(std::move(remote_location));
+  return register_file(std::move(data), FileLocationSource::FromUser, "from_persistent_id", false).move_as_ok();
+}
+
+FileView FileManager::get_file_view(FileId file_id) const {
+  auto file_node = get_file_node(file_id);
+  if (!file_node) {
+    return FileView();
+  }
+  return FileView(file_node);
+}
+FileView FileManager::get_sync_file_view(FileId file_id) {
+  auto file_node = get_sync_file_node(file_id);
+  if (!file_node) {
+    return FileView();
+  }
+  return FileView(file_node);
+}
+
+tl_object_ptr<td_api::file> FileManager::get_file_object(FileId file_id, bool with_main_file_id) {
+  auto file_view = get_sync_file_view(file_id);
+
+  if (file_view.empty()) {
+    return td_api::make_object<td_api::file>(0, 0, 0, td_api::make_object<td_api::localFile>(),
+                                             td_api::make_object<td_api::remoteFile>());
+  }
+
+  string persistent_file_id;
+  if (file_view.has_remote_location()) {
+    persistent_file_id = get_persistent_id(file_view.remote_location());
+  } else if (file_view.has_url()) {
+    persistent_file_id = file_view.url();
+  }
+
+  int32 size = narrow_cast<int32>(file_view.size());
+  int32 expected_size = narrow_cast<int32>(file_view.expected_size());
+  int32 local_size = narrow_cast<int32>(file_view.local_size());
+  int32 local_total_size = narrow_cast<int32>(file_view.local_total_size());
+  int32 remote_size = narrow_cast<int32>(file_view.remote_size());
+  string path = file_view.path();
+  bool can_be_downloaded = file_view.can_download_from_server() || file_view.can_generate();
+  bool can_be_deleted = file_view.can_delete();
+
+  auto result_file_id = file_id;
+  auto *file_info = get_file_id_info(result_file_id);
+  if (with_main_file_id) {
+    if (!file_info->send_updates_flag_) {
+      result_file_id = file_view.file_id();
+    }
+    file_info = get_file_id_info(file_view.file_id());
+  }
+  file_info->send_updates_flag_ = true;
+  VLOG(update_file) << "Send file " << file_id << " as " << result_file_id << " and update send_updates_flag_ for file "
+                    << (with_main_file_id ? file_view.file_id() : result_file_id);
+
+  return td_api::make_object<td_api::file>(
+      result_file_id.get(), size, expected_size,
+      td_api::make_object<td_api::localFile>(std::move(path), can_be_downloaded, can_be_deleted,
+                                             file_view.is_downloading(), file_view.has_local_location(), local_size,
+                                             local_total_size),
+      td_api::make_object<td_api::remoteFile>(std::move(persistent_file_id), file_view.is_uploading(),
+                                              file_view.has_remote_location(), remote_size));
+}
+
+Result<FileId> FileManager::check_input_file_id(FileType type, Result<FileId> result, bool is_encrypted,
+                                                bool allow_zero) {
+  TRY_RESULT(file_id, std::move(result));
+  if (allow_zero && !file_id.is_valid()) {
+    return FileId();
+  }
+
+  auto file_node = get_file_node(file_id);
+  if (!file_node) {
+    return Status::Error(6, "File not found");
+  }
+  auto file_view = FileView(file_node);
+  FileType real_type = file_view.get_type();
+  if (!is_encrypted) {
+    if (real_type != type && !(real_type == FileType::Temp && file_view.has_url()) &&
+        !(is_document_type(real_type) && is_document_type(type))) {
+      // TODO: send encrypted file to unencrypted chat
+      return Status::Error(6, "Type of file mismatch");
+    }
+  }
+
+  if (!file_view.has_remote_location()) {
+    // TODO why not return file_id here? We will dup it anyway
+    // But it will not be duped if has_input_media(), so for now we can't return main_file_id
+    return dup_file_id(file_id);
+  }
+  return file_node->main_file_id_;
+}
+
+Result<FileId> FileManager::get_input_thumbnail_file_id(const tl_object_ptr<td_api::InputFile> &thumbnail_input_file,
+                                                        DialogId owner_dialog_id, bool is_encrypted) {
+  if (thumbnail_input_file == nullptr) {
+    return Status::Error(6, "inputThumbnail not specified");
+  }
+
+  switch (thumbnail_input_file->get_id()) {
+    case td_api::inputFileLocal::ID: {
+      const string &path = static_cast<const td_api::inputFileLocal *>(thumbnail_input_file.get())->path_;
+      return register_local(
+          FullLocalFileLocation(is_encrypted ? FileType::EncryptedThumbnail : FileType::Thumbnail, path, 0),
+          owner_dialog_id, 0, false);
+    }
+    case td_api::inputFileId::ID:
+      return Status::Error(6, "InputFileId is not supported for thumbnails");
+    case td_api::inputFileRemote::ID:
+      return Status::Error(6, "InputFileRemote is not supported for thumbnails");
+    case td_api::inputFileGenerated::ID: {
+      auto *generated_thumbnail = static_cast<const td_api::inputFileGenerated *>(thumbnail_input_file.get());
+      return register_generate(is_encrypted ? FileType::EncryptedThumbnail : FileType::Thumbnail,
+                               FileLocationSource::FromUser, generated_thumbnail->original_path_,
+                               generated_thumbnail->conversion_, owner_dialog_id, generated_thumbnail->expected_size_);
+    }
+    default:
+      UNREACHABLE();
+      return Status::Error(500, "Unreachable");
+  }
+}
+
+Result<FileId> FileManager::get_input_file_id(FileType type, const tl_object_ptr<td_api::InputFile> &file,
+                                              DialogId owner_dialog_id, bool allow_zero, bool is_encrypted,
+                                              bool get_by_hash) {
+  if (is_encrypted) {
+    get_by_hash = false;
+  }
+  if (!file) {
+    if (allow_zero) {
+      return FileId();
+    }
+    return Status::Error(6, "InputFile not specified");
+  }
+
+  auto r_file_id = [&]() -> Result<FileId> {
+    switch (file->get_id()) {
+      case td_api::inputFileLocal::ID: {
+        const string &path = static_cast<const td_api::inputFileLocal *>(file.get())->path_;
+        if (allow_zero && path.empty()) {
+          return FileId();
+        }
+        return register_local(FullLocalFileLocation(is_encrypted ? FileType::Encrypted : type, path, 0),
+                              owner_dialog_id, 0, get_by_hash);
+      }
+      case td_api::inputFileId::ID: {
+        FileId file_id(static_cast<const td_api::inputFileId *>(file.get())->id_, 0);
+        if (!file_id.is_valid()) {
+          return FileId();
+        }
+        return file_id;
+      }
+      case td_api::inputFileRemote::ID: {
+        const string &file_persistent_id = static_cast<const td_api::inputFileRemote *>(file.get())->id_;
+        if (allow_zero && file_persistent_id.empty()) {
+          return FileId();
+        }
+        return from_persistent_id(file_persistent_id, type);
+      }
+      case td_api::inputFileGenerated::ID: {
+        auto *generated_file = static_cast<const td_api::inputFileGenerated *>(file.get());
+        return register_generate(is_encrypted ? FileType::Encrypted : type, FileLocationSource::FromUser,
+                                 generated_file->original_path_, generated_file->conversion_, owner_dialog_id,
+                                 generated_file->expected_size_);
+      }
+      default:
+        UNREACHABLE();
+        return Status::Error(500, "Unreachable");
+    }
+  }();
+
+  return check_input_file_id(type, std::move(r_file_id), is_encrypted, allow_zero);
+}
+
+vector<tl_object_ptr<telegram_api::InputDocument>> FileManager::get_input_documents(const vector<FileId> &file_ids) {
+  vector<tl_object_ptr<telegram_api::InputDocument>> result;
+  result.reserve(file_ids.size());
+  for (auto file_id : file_ids) {
+    auto file_view = get_file_view(file_id);
+    CHECK(!file_view.empty());
+    CHECK(file_view.has_remote_location());
+    CHECK(!file_view.remote_location().is_web());
+    result.push_back(file_view.remote_location().as_input_document());
+  }
+  return result;
+}
+
+FileId FileManager::next_file_id() {
+  if (!empty_file_ids_.empty()) {
+    auto res = empty_file_ids_.back();
+    empty_file_ids_.pop_back();
+    return FileId{res, 0};
+  }
+  FileId res(static_cast<int32>(file_id_info_.size()), 0);
+  // LOG(ERROR) << "NEXT file_id " << res;
+  file_id_info_.push_back({});
+  return res;
+}
+
+FileManager::FileNodeId FileManager::next_file_node_id() {
+  FileNodeId res = static_cast<FileNodeId>(file_nodes_.size());
+  file_nodes_.emplace_back(nullptr);
+  return res;
+}
+
+void FileManager::on_start_download(QueryId query_id) {
+  auto query = queries_container_.get(query_id);
+  CHECK(query != nullptr);
+
+  auto file_id = query->file_id_;
+  auto file_node = get_file_node(file_id);
+  if (!file_node) {
+    return;
+  }
+  if (file_node->download_id_ != query_id) {
+    return;
+  }
+
+  LOG(DEBUG) << "Start to download part of file " << file_id;
+  file_node->is_download_started_ = true;
+}
+
+void FileManager::on_partial_download(QueryId query_id, const PartialLocalFileLocation &partial_local,
+                                      int64 ready_size) {
+  auto query = queries_container_.get(query_id);
+  CHECK(query != nullptr);
+
+  auto file_id = query->file_id_;
+  auto file_node = get_file_node(file_id);
+  if (!file_node) {
+    return;
+  }
+  if (file_node->download_id_ != query_id) {
+    return;
+  }
+
+  file_node->set_local_location(LocalFileLocation(partial_local), ready_size);
+  try_flush_node(file_node);
+}
+
+void FileManager::on_partial_upload(QueryId query_id, const PartialRemoteFileLocation &partial_remote,
+                                    int64 ready_size) {
+  auto query = queries_container_.get(query_id);
+  CHECK(query != nullptr);
+
+  auto file_id = query->file_id_;
+  auto file_node = get_file_node(file_id);
+  if (!file_node) {
+    return;
+  }
+  if (file_node->upload_id_ != query_id) {
+    return;
+  }
+
+  file_node->set_remote_location(RemoteFileLocation(partial_remote), FileLocationSource::None, ready_size);
+  try_flush_node(file_node);
+}
+void FileManager::on_download_ok(QueryId query_id, const FullLocalFileLocation &local, int64 size) {
+  auto file_id = finish_query(query_id).first.file_id_;
+  LOG(INFO) << "ON DOWNLOAD OK file " << file_id << " of size " << size;
+  auto r_new_file_id = register_local(local, DialogId(), size);
+  if (r_new_file_id.is_error()) {
+    LOG(ERROR) << "Can't register local file after download: " << r_new_file_id.error();
+  } else {
+    context_->on_new_file(get_file_view(r_new_file_id.ok()).size());
+    LOG_STATUS(merge(r_new_file_id.ok(), file_id));
+  }
+}
+void FileManager::on_upload_ok(QueryId query_id, FileType file_type, const PartialRemoteFileLocation &partial_remote,
+                               int64 size) {
+  CHECK(partial_remote.ready_part_count_ == partial_remote.part_count_);
+  auto some_file_id = finish_query(query_id).first.file_id_;
+  LOG(INFO) << "ON UPLOAD OK file " << some_file_id << " of size " << size;
+
+  auto file_node = get_file_node(some_file_id);
+  if (!file_node) {
+    return;
+  }
+
+  FileId file_id;
+  uint64 file_id_upload_order{std::numeric_limits<uint64>::max()};
+  for (auto id : file_node->file_ids_) {
+    auto *info = get_file_id_info(id);
+    if (info->upload_priority_ != 0 && info->upload_order_ < file_id_upload_order) {
+      file_id = id;
+      file_id_upload_order = info->upload_order_;
+    }
+  }
+  if (!file_id.is_valid()) {
+    return;
+  }
+
+  auto *file_info = get_file_id_info(file_id);
+  file_info->upload_priority_ = 0;
+  file_info->download_priority_ = 0;
+
+  FileView file_view(file_node);
+  string file_name = get_file_name(file_type, file_view.suggested_name());
+
+  if (file_view.is_encrypted()) {
+    tl_object_ptr<telegram_api::InputEncryptedFile> input_file;
+    if (partial_remote.is_big_) {
+      input_file = make_tl_object<telegram_api::inputEncryptedFileBigUploaded>(
+          partial_remote.file_id_, partial_remote.part_count_, file_view.encryption_key().calc_fingerprint());
+    } else {
+      input_file = make_tl_object<telegram_api::inputEncryptedFileUploaded>(
+          partial_remote.file_id_, partial_remote.part_count_, "", file_view.encryption_key().calc_fingerprint());
+    }
+    if (file_info->upload_callback_) {
+      file_info->upload_callback_->on_upload_encrypted_ok(file_id, std::move(input_file));
+      file_node->upload_pause_ = file_id;
+      file_info->upload_callback_.reset();
+    }
+  } else {
+    tl_object_ptr<telegram_api::InputFile> input_file;
+    if (partial_remote.is_big_) {
+      input_file = make_tl_object<telegram_api::inputFileBig>(partial_remote.file_id_, partial_remote.part_count_,
+                                                              std::move(file_name));
+    } else {
+      input_file = make_tl_object<telegram_api::inputFile>(partial_remote.file_id_, partial_remote.part_count_,
+                                                           std::move(file_name), "");
+    }
+    if (file_info->upload_callback_) {
+      file_info->upload_callback_->on_upload_ok(file_id, std::move(input_file));
+      file_node->upload_pause_ = file_id;
+      file_info->upload_callback_.reset();
+    }
+  }
+}
+
+void FileManager::on_upload_full_ok(QueryId query_id, const FullRemoteFileLocation &remote) {
+  LOG(INFO) << "ON UPLOAD OK";
+  auto file_id = finish_query(query_id).first.file_id_;
+  auto new_file_id = register_remote(remote, FileLocationSource::FromServer, DialogId(), 0, 0, "");
+  LOG_STATUS(merge(new_file_id, file_id));
+}
+
+void FileManager::on_partial_generate(QueryId query_id, const PartialLocalFileLocation &partial_local,
+                                      int32 expected_size) {
+  LOG(INFO) << "on_parital_generate: " << partial_local.path_ << " " << partial_local.ready_part_count_;
+  auto query = queries_container_.get(query_id);
+  CHECK(query != nullptr);
+
+  auto file_id = query->file_id_;
+  auto file_node = get_file_node(file_id);
+  if (!file_node) {
+    return;
+  }
+  if (file_node->generate_id_ != query_id) {
+    return;
+  }
+  file_node->set_local_location(LocalFileLocation(partial_local), 0);
+  // TODO check for size and local_size, abort generation if needed
+  if (expected_size != 0) {
+    file_node->set_expected_size(expected_size);
+  }
+  if (!file_node->generate_was_update_) {
+    file_node->generate_was_update_ = true;
+    run_upload(file_node, {});
+  }
+  if (file_node->upload_id_ != 0) {
+    send_closure(file_load_manager_, &FileLoadManager::update_local_file_location, file_node->upload_id_,
+                 LocalFileLocation(partial_local));
+  }
+
+  try_flush_node(file_node);
+}
+void FileManager::on_generate_ok(QueryId query_id, const FullLocalFileLocation &local) {
+  LOG(INFO) << "on_ok_generate: " << local;
+  Query query;
+  bool was_active;
+  std::tie(query, was_active) = finish_query(query_id);
+  auto generate_file_id = query.file_id_;
+
+  auto file_node = get_file_node(generate_file_id);
+  if (!file_node) {
+    return;
+  }
+
+  auto old_upload_id = file_node->upload_id_;
+
+  auto r_new_file_id = register_local(local, DialogId(), 0);
+  Status status;
+  if (r_new_file_id.is_error()) {
+    status = Status::Error(PSLICE() << "Can't register local file after generate: " << r_new_file_id.error());
+  } else {
+    auto result = merge(r_new_file_id.ok(), generate_file_id);
+    if (result.is_error()) {
+      status = result.move_as_error();
+    }
+  }
+  file_node = get_file_node(generate_file_id);
+  if (status.is_error()) {
+    return on_error_impl(file_node, query.type_, was_active, std::move(status));
+  }
+
+  CHECK(file_node);
+  context_->on_new_file(FileView(file_node).size());
+
+  run_upload(file_node, {});
+
+  if (was_active) {
+    if (old_upload_id != 0 && old_upload_id == file_node->upload_id_) {
+      send_closure(file_load_manager_, &FileLoadManager::update_local_file_location, file_node->upload_id_,
+                   LocalFileLocation(local));
+    }
+  }
+}
+
+void FileManager::on_error(QueryId query_id, Status status) {
+  Query query;
+  bool was_active;
+  std::tie(query, was_active) = finish_query(query_id);
+  auto node = get_file_node(query.file_id_);
+  if (!node) {
+    LOG(ERROR) << "Can't find file node for " << query.file_id_ << " " << status;
+    return;
+  }
+
+  if (query.type_ == Query::UploadByHash) {
+    LOG(INFO) << "Upload By Hash failed: " << status << ", restart upload";
+    node->get_by_hash_ = false;
+    run_upload(node, {});
+    return;
+  }
+  on_error_impl(node, query.type_, was_active, std::move(status));
+}
+
+void FileManager::on_error_impl(FileNodePtr node, FileManager::Query::Type type, bool was_active, Status status) {
+  SCOPE_EXIT {
+    try_flush_node(node);
+  };
+  if (status.code() != 1) {
+    LOG(WARNING) << "Failed to upload/download/generate file: " << status << ". Query type = " << type
+                 << ". File type is " << file_type_name[static_cast<int32>(FileView(node).get_type())];
+    if (status.code() == 0) {
+      // Remove partial locations
+      if (node->local_.type() == LocalFileLocation::Type::Partial && status.message() != "FILE_UPLOAD_RESTART") {
+        LOG(INFO) << "Unlink file " << node->local_.partial().path_;
+        unlink(node->local_.partial().path_).ignore();
+        node->set_local_location(LocalFileLocation(), 0);
+      }
+      if (node->remote_.type() == RemoteFileLocation::Type::Partial) {
+        node->set_remote_location(RemoteFileLocation(), FileLocationSource::None, 0);
+      }
+      status = Status::Error(400, status.message());
+    }
+  }
+
+  if (status.message() == "FILE_UPLOAD_RESTART") {
+    run_upload(node, {});
+    return;
+  }
+  if (status.message() == "FILE_DOWNLOAD_RESTART") {
+    node->can_search_locally_ = false;
+    run_download(node);
+    return;
+  }
+
+  if (!was_active) {
+    return;
+  }
+
+  // Stop everything on error
+  cancel_generate(node);
+  cancel_download(node);
+  cancel_upload(node);
+
+  for (auto file_id : vector<FileId>(node->file_ids_)) {
+    auto *info = get_file_id_info(file_id);
+    if (info->download_priority_ != 0) {
+      info->download_priority_ = 0;
+      if (info->download_callback_) {
+        info->download_callback_->on_download_error(file_id, status.clone());
+        info->download_callback_.reset();
+      }
+    }
+    if (info->upload_priority_ != 0) {
+      info->upload_priority_ = 0;
+      if (info->upload_callback_) {
+        info->upload_callback_->on_upload_error(file_id, status.clone());
+        info->upload_callback_.reset();
+      }
+    }
+  }
+}
+
+std::pair<FileManager::Query, bool> FileManager::finish_query(QueryId query_id) {
+  SCOPE_EXIT {
+    queries_container_.erase(query_id);
+  };
+  auto query = queries_container_.get(query_id);
+  CHECK(query != nullptr);
+
+  auto res = *query;
+  auto node = get_file_node(res.file_id_);
+  if (!node) {
+    return std::make_pair(res, false);
+  }
+  bool was_active = false;
+  if (node->generate_id_ == query_id) {
+    node->generate_id_ = 0;
+    node->generate_was_update_ = false;
+    node->set_generate_priority(0, 0);
+    was_active = true;
+  }
+  if (node->download_id_ == query_id) {
+    node->download_id_ = 0;
+    node->is_download_started_ = false;
+    node->set_download_priority(0);
+    was_active = true;
+  }
+  if (node->upload_id_ == query_id) {
+    node->upload_id_ = 0;
+    node->set_upload_priority(0);
+    was_active = true;
+  }
+  return std::make_pair(res, was_active);
+}
+
+FullRemoteFileLocation *FileManager::get_remote(int32 key) {
+  if (key == 0) {
+    return nullptr;
+  }
+  return &remote_location_info_.get(key).remote_;
+}
+
+void FileManager::hangup() {
+  file_db_.reset();
+  file_generate_manager_.reset();
+  file_load_manager_.reset();
+  stop();
+}
+
+void FileManager::tear_down() {
+  parent_.reset();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileManager.h b/libs/tdlib/td/td/telegram/files/FileManager.h
new file mode 100644
index 0000000000..10f961c213
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileManager.h
@@ -0,0 +1,475 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/DialogId.h"
+#include "td/telegram/files/FileDb.h"
+#include "td/telegram/files/FileGenerateManager.h"
+#include "td/telegram/files/FileId.h"
+#include "td/telegram/files/FileLoadManager.h"
+#include "td/telegram/files/FileLocation.h"
+#include "td/telegram/files/FileStats.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/Container.h"
+#include "td/utils/Enumerator.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <map>
+#include <memory>
+#include <set>
+#include <utility>
+
+namespace td {
+
+enum class FileLocationSource : int8 { None, FromUser, FromDb, FromServer };
+
+class FileNode {
+ public:
+  FileNode(LocalFileLocation local, RemoteFileLocation remote, unique_ptr<FullGenerateFileLocation> generate,
+           int64 size, int64 expected_size, string remote_name, string url, DialogId owner_dialog_id,
+           FileEncryptionKey key, FileId main_file_id, int8 main_file_id_priority)
+      : local_(std::move(local))
+      , remote_(std::move(remote))
+      , generate_(std::move(generate))
+      , size_(size)
+      , expected_size_(expected_size)
+      , remote_name_(std::move(remote_name))
+      , url_(std::move(url))
+      , owner_dialog_id_(owner_dialog_id)
+      , encryption_key_(std::move(key))
+      , main_file_id_(main_file_id)
+      , main_file_id_priority_(main_file_id_priority) {
+  }
+  void set_local_location(const LocalFileLocation &local, int64 ready_size);
+  void set_remote_location(const RemoteFileLocation &remote, FileLocationSource source, int64 ready_size);
+  void set_generate_location(unique_ptr<FullGenerateFileLocation> &&generate);
+  void set_size(int64 size);
+  void set_expected_size(int64 expected_size);
+  void set_remote_name(string remote_name);
+  void set_url(string url);
+  void set_owner_dialog_id(DialogId owner_id);
+  void set_encryption_key(FileEncryptionKey key);
+
+  void set_download_priority(int8 priority);
+  void set_upload_priority(int8 priority);
+  void set_generate_priority(int8 download_priority, int8 upload_priority);
+
+  void on_changed();
+  void on_info_changed();
+  void on_pmc_changed();
+
+  bool need_info_flush() const;
+  bool need_pmc_flush() const;
+
+  void on_pmc_flushed();
+  void on_info_flushed();
+
+  string suggested_name() const;
+
+ private:
+  friend class FileView;
+  friend class FileManager;
+
+  LocalFileLocation local_;
+  FileLoadManager::QueryId upload_id_ = 0;
+  int64 local_ready_size_ = 0;
+
+  RemoteFileLocation remote_;
+  FileLoadManager::QueryId download_id_ = 0;
+  int64 remote_ready_size_ = 0;
+
+  unique_ptr<FullGenerateFileLocation> generate_;
+  FileLoadManager::QueryId generate_id_ = 0;
+
+  int64 size_ = 0;
+  int64 expected_size_ = 0;
+  string remote_name_;
+  string url_;
+  DialogId owner_dialog_id_;
+  FileEncryptionKey encryption_key_;
+  FileDbId pmc_id_ = 0;
+  std::vector<FileId> file_ids_;
+
+  FileId main_file_id_;
+
+  FileId upload_pause_;
+  int8 upload_priority_ = 0;
+  int8 download_priority_ = 0;
+  int8 generate_priority_ = 0;
+
+  int8 generate_download_priority_ = 0;
+  int8 generate_upload_priority_ = 0;
+
+  int8 main_file_id_priority_ = 0;
+
+  FileLocationSource remote_source_ = FileLocationSource::FromUser;
+
+  bool get_by_hash_ = false;
+  bool can_search_locally_{true};
+
+  bool is_download_started_ = false;
+  bool generate_was_update_ = false;
+
+  bool need_load_from_pmc_ = false;
+
+  bool pmc_changed_flag_{false};
+  bool info_changed_flag_{false};
+};
+
+class FileManager;
+
+class FileNodePtr {
+ public:
+  FileNodePtr() = default;
+  FileNodePtr(FileId file_id, FileManager *file_manager) : file_id_(file_id), file_manager_(file_manager) {
+  }
+
+  FileNode *operator->() const;
+  FileNode &operator*() const;
+  FileNode *get() const;
+  FullRemoteFileLocation *get_remote() const;
+  explicit operator bool() const;
+
+ private:
+  FileId file_id_;
+  FileManager *file_manager_ = nullptr;
+  FileNode *get_unsafe() const;
+};
+
+class ConstFileNodePtr {
+ public:
+  ConstFileNodePtr() = default;
+  ConstFileNodePtr(FileNodePtr file_node_ptr) : file_node_ptr_(file_node_ptr) {
+  }
+
+  const FileNode *operator->() const {
+    return file_node_ptr_.operator->();
+  }
+  const FileNode &operator*() const {
+    return file_node_ptr_.operator*();
+  }
+
+  explicit operator bool() const {
+    return bool(file_node_ptr_);
+  }
+  const FullRemoteFileLocation *get_remote() const {
+    return file_node_ptr_.get_remote();
+  }
+
+ private:
+  FileNodePtr file_node_ptr_;
+};
+
+class FileView {
+ public:
+  FileView() = default;
+  explicit FileView(ConstFileNodePtr node);
+
+  bool empty() const;
+
+  bool has_local_location() const;
+  const FullLocalFileLocation &local_location() const;
+  bool has_remote_location() const;
+  const FullRemoteFileLocation &remote_location() const;
+  bool has_generate_location() const;
+  const FullGenerateFileLocation &generate_location() const;
+
+  bool has_url() const;
+  const string &url() const;
+
+  const string &remote_name() const;
+
+  string suggested_name() const;
+
+  DialogId owner_dialog_id() const;
+
+  bool get_by_hash() const;
+
+  FileId file_id() const {
+    return node_->main_file_id_;
+  }
+
+  int64 size() const;
+  int64 expected_size() const;
+  bool is_downloading() const;
+  int64 local_size() const;
+  int64 local_total_size() const;
+  bool is_uploading() const;
+  int64 remote_size() const;
+  string path() const;
+
+  bool can_download_from_server() const;
+  bool can_generate() const;
+  bool can_delete() const;
+
+  FileType get_type() const {
+    if (has_local_location()) {
+      return local_location().file_type_;
+    }
+    if (has_remote_location()) {
+      return remote_location().file_type_;
+    }
+    if (has_generate_location()) {
+      return generate_location().file_type_;
+    }
+    return FileType::Temp;
+  }
+  bool is_encrypted() const {
+    return get_type() == FileType::Encrypted;
+  }
+  const FileEncryptionKey &encryption_key() const {
+    return node_->encryption_key_;
+  }
+
+ private:
+  ConstFileNodePtr node_{};
+};
+
+class Td;
+class FileManager : public FileLoadManager::Callback {
+ public:
+  class DownloadCallback {
+   public:
+    DownloadCallback() = default;
+    DownloadCallback(const DownloadCallback &) = delete;
+    DownloadCallback &operator=(const DownloadCallback &) = delete;
+    virtual ~DownloadCallback() = default;
+    virtual void on_progress(FileId file_id) {
+    }
+
+    virtual void on_download_ok(FileId file_id) = 0;
+    virtual void on_download_error(FileId file_id, Status error) = 0;
+  };
+
+  class UploadCallback {
+   public:
+    UploadCallback() = default;
+    UploadCallback(const UploadCallback &) = delete;
+    UploadCallback &operator=(const UploadCallback &) = delete;
+    virtual ~UploadCallback() = default;
+
+    virtual void on_progress(FileId file_id) {
+    }
+
+    // After on_upload_ok all uploads of this file will be paused till merge, delete_partial_remote_location or
+    // explicit upload request with the same file_id.
+    // Also upload may be resumed after some other merges.
+    virtual void on_upload_ok(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) = 0;
+    virtual void on_upload_encrypted_ok(FileId file_id, tl_object_ptr<telegram_api::InputEncryptedFile> input_file) = 0;
+    virtual void on_upload_error(FileId file_id, Status error) = 0;
+  };
+
+  class Context {
+   public:
+    virtual void on_new_file(int64 size) = 0;
+    virtual void on_file_updated(FileId size) = 0;
+    virtual ActorShared<> create_reference() = 0;
+    Context() = default;
+    Context(const Context &) = delete;
+    Context &operator=(const Context &) = delete;
+    virtual ~Context() = default;
+  };
+
+  explicit FileManager(std::unique_ptr<Context> context);
+  FileManager(const FileManager &other) = delete;
+  FileManager &operator=(const FileManager &other) = delete;
+  FileManager(FileManager &&other) = delete;
+  FileManager &operator=(FileManager &&other) = delete;
+  ~FileManager() override;
+
+  void init_actor();
+
+  FileId dup_file_id(FileId file_id);
+
+  void on_file_unlink(const FullLocalFileLocation &location);
+
+  FileId register_empty(FileType type);
+  Result<FileId> register_local(FullLocalFileLocation location, DialogId owner_dialog_id, int64 size,
+                                bool get_by_hash = false, bool force = false) TD_WARN_UNUSED_RESULT;
+  FileId register_remote(const FullRemoteFileLocation &location, FileLocationSource file_location_source,
+                         DialogId owner_dialog_id, int64 size, int64 expected_size, string name) TD_WARN_UNUSED_RESULT;
+  Result<FileId> register_generate(FileType file_type, FileLocationSource file_location_source, string original_path,
+                                   string conversion, DialogId owner_dialog_id,
+                                   int64 expected_size) TD_WARN_UNUSED_RESULT;
+  Result<FileId> register_file(FileData data, FileLocationSource file_location_source, const char *source, bool force);
+
+  Result<FileId> merge(FileId x_file_id, FileId y_file_id, bool no_sync = false) TD_WARN_UNUSED_RESULT;
+
+  bool set_encryption_key(FileId file_id, FileEncryptionKey key);
+  bool set_content(FileId file_id, BufferSlice bytes);
+
+  void download(FileId file_id, std::shared_ptr<DownloadCallback> callback, int32 new_priority);
+  void upload(FileId file_id, std::shared_ptr<UploadCallback> callback, int32 new_priority, uint64 upload_order);
+  void resume_upload(FileId file_id, std::vector<int> bad_parts, std::shared_ptr<UploadCallback> callback,
+                     int32 new_priority, uint64 upload_order);
+  bool delete_partial_remote_location(FileId file_id);
+  void get_content(FileId file_id, Promise<BufferSlice> promise);
+
+  void delete_file(FileId file_id, Promise<Unit> promise, const char *source);
+
+  void external_file_generate_progress(int64 id, int32 expected_size, int32 local_prefix_size, Promise<> promise);
+  void external_file_generate_finish(int64 id, Status status, Promise<> promise);
+
+  static constexpr char PERSISTENT_ID_VERSION = 2;
+  Result<string> to_persistent_id(FileId file_id) TD_WARN_UNUSED_RESULT;
+  Result<FileId> from_persistent_id(CSlice persistent_id, FileType file_type) TD_WARN_UNUSED_RESULT;
+  FileView get_file_view(FileId file_id) const;
+  FileView get_sync_file_view(FileId file_id);
+  tl_object_ptr<td_api::file> get_file_object(FileId file_id, bool with_main_file_id = true);
+
+  Result<FileId> get_input_thumbnail_file_id(const tl_object_ptr<td_api::InputFile> &thumb_input_file,
+                                             DialogId owner_dialog_id, bool is_encrypted) TD_WARN_UNUSED_RESULT;
+  Result<FileId> get_input_file_id(FileType type, const tl_object_ptr<td_api::InputFile> &file,
+                                   DialogId owner_dialog_id, bool allow_zero, bool is_encrypted,
+                                   bool get_by_hash = false) TD_WARN_UNUSED_RESULT;
+
+  vector<tl_object_ptr<telegram_api::InputDocument>> get_input_documents(const vector<FileId> &file_ids);
+
+  template <class T>
+  void store_file(FileId file_id, T &storer, int32 ttl = 5) const;
+
+  template <class T>
+  FileId parse_file(T &parser);
+
+ private:
+  Result<FileId> check_input_file_id(FileType type, Result<FileId> result, bool is_encrypted,
+                                     bool allow_zero) TD_WARN_UNUSED_RESULT;
+
+  FileId register_url(string url, FileType file_type, FileLocationSource file_location_source,
+                      DialogId owner_dialog_id);
+
+  static constexpr int8 FROM_BYTES_PRIORITY = 10;
+  using FileNodeId = int32;
+  using QueryId = FileLoadManager::QueryId;
+  class Query {
+   public:
+    FileId file_id_;
+    enum Type { UploadByHash, Upload, Download, SetContent, Generate } type_;
+  };
+  struct FileIdInfo {
+    FileNodeId node_id_{0};
+    bool send_updates_flag_{false};
+    bool pin_flag_{false};
+
+    int8 download_priority_{0};
+    int8 upload_priority_{0};
+
+    uint64 upload_order_;
+
+    std::shared_ptr<DownloadCallback> download_callback_;
+    std::shared_ptr<UploadCallback> upload_callback_;
+  };
+
+  ActorShared<> parent_;
+  std::unique_ptr<Context> context_;
+  std::shared_ptr<FileDbInterface> file_db_;
+
+  FileIdInfo *get_file_id_info(FileId file_id);
+
+  struct RemoteInfo {
+    // mutible is set to to enable changing access hash
+    mutable FullRemoteFileLocation remote_;
+    FileId file_id_;
+    bool operator==(const RemoteInfo &other) const {
+      return this->remote_ == other.remote_;
+    }
+    bool operator<(const RemoteInfo &other) const {
+      return this->remote_ < other.remote_;
+    }
+  };
+  Enumerator<RemoteInfo> remote_location_info_;
+
+  std::map<FullLocalFileLocation, FileId> local_location_to_file_id_;
+  std::map<FullGenerateFileLocation, FileId> generate_location_to_file_id_;
+  std::map<FileDbId, int32> pmc_id_to_file_node_id_;
+
+  vector<FileIdInfo> file_id_info_;
+  vector<int32> empty_file_ids_;
+  vector<std::unique_ptr<FileNode>> file_nodes_;
+  ActorOwn<FileLoadManager> file_load_manager_;
+  ActorOwn<FileGenerateManager> file_generate_manager_;
+
+  Container<Query> queries_container_;
+
+  std::set<std::string> bad_paths_;
+
+  FileId next_file_id();
+  FileNodeId next_file_node_id();
+  int32 next_pmc_file_id();
+  FileId create_file_id(int32 file_node_id, FileNode *file_node);
+  void try_forget_file_id(FileId file_id);
+
+  void load_from_pmc(FileId file_id, FullLocalFileLocation full_local);
+  void load_from_pmc(FileId file_id, const FullRemoteFileLocation &full_remote);
+  void load_from_pmc(FileId file_id, const FullGenerateFileLocation &full_generate);
+  template <class LocationT>
+  void load_from_pmc_impl(FileId file_id, const LocationT &location);
+  void load_from_pmc_result(FileId file_id, Result<FileData> &&result);
+  FileId register_pmc_file_data(FileData &&data);
+
+  Status check_local_location(FileNodePtr node);
+  Status check_local_location(FullLocalFileLocation &location, int64 &size);
+  void try_flush_node(FileNodePtr node, bool new_remote = false, bool new_local = false, bool new_generate = false,
+                      FileDbId other_pmc_id = Auto());
+  void try_flush_node_info(FileNodePtr node);
+  void clear_from_pmc(FileNodePtr node);
+  void flush_to_pmc(FileNodePtr node, bool new_remote, bool new_local, bool new_generate);
+  void load_from_pmc(FileNodePtr node, bool new_remote, bool new_local, bool new_generate);
+
+  string get_persistent_id(const FullRemoteFileLocation &location);
+
+  string fix_file_extension(Slice file_name, Slice file_type, Slice file_extension);
+  string get_file_name(FileType file_type, Slice path);
+
+  ConstFileNodePtr get_file_node(FileId file_id) const {
+    return ConstFileNodePtr{FileNodePtr{file_id, const_cast<FileManager *>(this)}};
+  }
+  FileNodePtr get_file_node(FileId file_id) {
+    return FileNodePtr{file_id, this};
+  }
+  FileNode *get_file_node_raw(FileId file_id, FileNodeId *file_node_id = nullptr);
+
+  FileNodePtr get_sync_file_node(FileId file_id);
+
+  // void release_file_node(FileNodeId id);
+  void cancel_download(FileNodePtr node);
+  void cancel_upload(FileNodePtr node);
+  void cancel_generate(FileNodePtr node);
+  void run_upload(FileNodePtr node, std::vector<int> bad_parts);
+  void run_download(FileNodePtr node);
+  void run_generate(FileNodePtr node);
+
+  void on_start_download(QueryId query_id) override;
+  void on_partial_download(QueryId query_id, const PartialLocalFileLocation &partial_local, int64 ready_size) override;
+  void on_partial_upload(QueryId query_id, const PartialRemoteFileLocation &partial_remote, int64 ready_size) override;
+  void on_download_ok(QueryId query_id, const FullLocalFileLocation &local, int64 size) override;
+  void on_upload_ok(QueryId query_id, FileType file_type, const PartialRemoteFileLocation &partial_remote,
+                    int64 size) override;
+  void on_upload_full_ok(QueryId query_id, const FullRemoteFileLocation &remote) override;
+  void on_error(QueryId query_id, Status status) override;
+
+  void on_error_impl(FileNodePtr node, Query::Type type, bool was_active, Status status);
+
+  void on_partial_generate(QueryId, const PartialLocalFileLocation &partial_local, int32 expected_size);
+  void on_generate_ok(QueryId, const FullLocalFileLocation &local);
+
+  std::pair<Query, bool> finish_query(QueryId query_id);
+
+  FullRemoteFileLocation *get_remote(int32 key);
+
+  void hangup() override;
+  void tear_down() override;
+
+  friend class FileNodePtr;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileManager.hpp b/libs/tdlib/td/td/telegram/files/FileManager.hpp
new file mode 100644
index 0000000000..28f481308e
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileManager.hpp
@@ -0,0 +1,222 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/DialogId.h"
+#include "td/telegram/files/FileManager.h"
+#include "td/telegram/Version.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Slice.h"
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+
+enum class FileStoreType : int32 { Empty, Url, Generate, Local, Remote };
+
+template <class StorerT>
+void FileManager::store_file(FileId file_id, StorerT &storer, int32 ttl) const {
+  auto file_store_type = FileStoreType::Empty;
+  auto file_view = get_file_view(file_id);
+  if (file_view.empty() || ttl <= 0) {
+  } else if (file_view.has_remote_location()) {
+    file_store_type = FileStoreType::Remote;
+  } else if (file_view.has_local_location()) {
+    file_store_type = FileStoreType::Local;
+  } else if (file_view.has_url()) {
+    file_store_type = FileStoreType::Url;
+  } else if (file_view.has_generate_location()) {
+    file_store_type = FileStoreType::Generate;
+  }
+
+  store(file_store_type, storer);
+
+  bool has_encryption_key = false;
+  bool has_expected_size =
+      file_store_type == FileStoreType::Remote && file_view.size() == 0 && file_view.expected_size() != 0;
+  if (file_store_type != FileStoreType::Empty) {
+    has_encryption_key = !file_view.empty() && file_view.is_encrypted();
+    BEGIN_STORE_FLAGS();
+    STORE_FLAG(has_encryption_key);
+    STORE_FLAG(has_expected_size);
+    END_STORE_FLAGS();
+  }
+
+  switch (file_store_type) {
+    case FileStoreType::Empty:
+      break;
+    case FileStoreType::Url:
+      store(file_view.get_type(), storer);
+      store(file_view.url(), storer);
+      store(file_view.owner_dialog_id(), storer);
+      break;
+    case FileStoreType::Remote: {
+      store(file_view.remote_location(), storer);
+      if (has_expected_size) {
+        store(narrow_cast<int32>(file_view.expected_size()), storer);
+      } else {
+        store(narrow_cast<int32>(file_view.size()), storer);
+      }
+      store(file_view.remote_name(), storer);
+      store(file_view.owner_dialog_id(), storer);
+      break;
+    }
+    case FileStoreType::Local: {
+      store(file_view.local_location(), storer);
+      store(narrow_cast<int32>(file_view.size()), storer);
+      store(static_cast<int32>(file_view.get_by_hash()), storer);
+      store(file_view.owner_dialog_id(), storer);
+      break;
+    }
+    case FileStoreType::Generate: {
+      auto generate_location = file_view.generate_location();
+      FileId from_file_id;
+      bool have_file_id = false;
+      if (generate_location.conversion_ == "#_file_id#") {
+        break;
+      } else if (begins_with(generate_location.conversion_, "#file_id#")) {
+        // It is not the best possible way to serialize file_id
+        from_file_id =
+            FileId(to_integer<int32>(Slice(generate_location.conversion_).remove_prefix(Slice("#file_id#").size())), 0);
+        generate_location.conversion_ = "#_file_id#";
+        have_file_id = true;
+      }
+      store(generate_location, storer);
+      store(static_cast<int32>(0), storer);  // expected_size
+      store(static_cast<int32>(0), storer);
+      store(file_view.owner_dialog_id(), storer);
+
+      if (have_file_id) {
+        store_file(from_file_id, storer, ttl - 1);
+      }
+      break;
+    }
+  }
+  if (has_encryption_key) {
+    store(file_view.encryption_key(), storer);
+  }
+}
+
+template <class ParserT>
+FileId FileManager::parse_file(ParserT &parser) {
+  if (parser.version() < static_cast<int32>(Version::StoreFileId)) {
+    return FileId();
+  }
+
+  FileStoreType file_store_type;
+  parse(file_store_type, parser);
+
+  bool has_encryption_key = false;
+  bool has_expected_size = false;
+  if (file_store_type != FileStoreType::Empty) {
+    if (parser.version() >= static_cast<int32>(Version::StoreFileEncryptionKey)) {
+      BEGIN_PARSE_FLAGS();
+      PARSE_FLAG(has_encryption_key);
+      PARSE_FLAG(has_expected_size);
+      END_PARSE_FLAGS();
+    }
+  }
+
+  auto file_id = [&] {
+    switch (file_store_type) {
+      case FileStoreType::Empty:
+        return FileId();
+      case FileStoreType::Remote: {
+        FullRemoteFileLocation full_remote_location;
+        parse(full_remote_location, parser);
+        int32 size = 0;
+        int32 expected_size = 0;
+        if (has_expected_size) {
+          parse(expected_size, parser);
+        } else {
+          parse(size, parser);
+        }
+        string name;
+        parse(name, parser);
+        DialogId owner_dialog_id;
+        if (parser.version() >= static_cast<int32>(Version::StoreFileOwnerId)) {
+          parse(owner_dialog_id, parser);
+        }
+        return register_remote(full_remote_location, FileLocationSource::FromDb, owner_dialog_id, size, expected_size,
+                               name);
+      }
+      case FileStoreType::Local: {
+        FullLocalFileLocation full_local_location;
+        parse(full_local_location, parser);
+        int32 size;
+        parse(size, parser);
+        int32 get_by_hash;
+        parse(get_by_hash, parser);
+        DialogId owner_dialog_id;
+        if (parser.version() >= static_cast<int32>(Version::StoreFileOwnerId)) {
+          parse(owner_dialog_id, parser);
+        }
+        auto r_file_id = register_local(full_local_location, owner_dialog_id, size, get_by_hash != 0);
+        if (r_file_id.is_ok()) {
+          return r_file_id.move_as_ok();
+        }
+        LOG(ERROR) << "Can't resend local file " << full_local_location.path_;
+        return register_empty(full_local_location.file_type_);
+      }
+      case FileStoreType::Generate: {
+        FullGenerateFileLocation full_generated_location;
+        parse(full_generated_location, parser);
+        int32 expected_size;
+        parse(expected_size, parser);  // expected_size
+        int32 zero;
+        parse(zero, parser);
+        DialogId owner_dialog_id;
+        if (parser.version() >= static_cast<int32>(Version::StoreFileOwnerId)) {
+          parse(owner_dialog_id, parser);
+        }
+        if (begins_with(full_generated_location.conversion_, "#file_id#")) {
+          LOG(ERROR) << "Can't resend message with '#file_id#...' location";
+          return register_empty(full_generated_location.file_type_);
+        }
+        if (full_generated_location.conversion_ == "#_file_id#") {
+          auto file_id = parse_file(parser);
+          if (file_id.empty()) {
+            return register_empty(full_generated_location.file_type_);
+          }
+          auto download_file_id = dup_file_id(file_id);
+          full_generated_location.conversion_ = PSTRING() << "#file_id#" << download_file_id.get();
+        }
+
+        auto r_file_id = register_generate(full_generated_location.file_type_, FileLocationSource::FromDb,
+                                           full_generated_location.original_path_, full_generated_location.conversion_,
+                                           owner_dialog_id, expected_size);
+        if (r_file_id.is_ok()) {
+          return r_file_id.move_as_ok();
+        }
+        return register_empty(full_generated_location.file_type_);
+      }
+      case FileStoreType::Url: {
+        FileType type;
+        string url;
+        parse(type, parser);
+        parse(url, parser);
+        DialogId owner_dialog_id;
+        if (parser.version() >= static_cast<int32>(Version::StoreFileOwnerId)) {
+          parse(owner_dialog_id, parser);
+        }
+        return register_url(url, type, FileLocationSource::FromDb, owner_dialog_id);
+      }
+    }
+    return FileId();
+  }();
+
+  if (has_encryption_key) {
+    FileEncryptionKey encryption_key;
+    parse(encryption_key, parser);
+    set_encryption_key(file_id, std::move(encryption_key));
+  }
+
+  return file_id;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileStats.cpp b/libs/tdlib/td/td/telegram/files/FileStats.cpp
new file mode 100644
index 0000000000..8c93f01ce3
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileStats.cpp
@@ -0,0 +1,221 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/files/FileStats.h"
+
+#include "td/telegram/td_api.h"
+
+#include "td/telegram/files/FileLoaderUtils.h"
+#include "td/telegram/Global.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+
+#include <algorithm>
+#include <unordered_set>
+#include <utility>
+
+namespace td {
+
+tl_object_ptr<td_api::storageStatisticsFast> FileStatsFast::as_td_api() const {
+  return make_tl_object<td_api::storageStatisticsFast>(size, count, db_size);
+}
+
+void FileStats::add(StatByType &by_type, FileType file_type, int64 size) {
+  auto pos = static_cast<size_t>(file_type);
+  CHECK(pos < stat_by_type.size());
+  by_type[pos].size += size;
+  by_type[pos].cnt++;
+}
+
+void FileStats::add(FullFileInfo &&info) {
+  if (split_by_owner_dialog_id) {
+    add(stat_by_owner_dialog_id[info.owner_dialog_id], info.file_type, info.size);
+  } else {
+    add(stat_by_type, info.file_type, info.size);
+  }
+  if (need_all_files) {
+    all_files.emplace_back(std::move(info));
+  }
+}
+
+FileTypeStat get_nontemp_stat(const FileStats::StatByType &by_type) {
+  FileTypeStat stat;
+  for (size_t i = 0; i < file_type_size; i++) {
+    if (FileType(i) != FileType::Temp) {
+      stat.size += by_type[i].size;
+      stat.cnt += by_type[i].cnt;
+    }
+  }
+  return stat;
+}
+FileTypeStat FileStats::get_total_nontemp_stat() const {
+  if (!split_by_owner_dialog_id) {
+    return get_nontemp_stat(stat_by_type);
+  }
+  FileTypeStat stat;
+  for (auto &dialog : stat_by_owner_dialog_id) {
+    auto tmp = get_nontemp_stat(dialog.second);
+    stat.size += tmp.size;
+    stat.cnt += tmp.cnt;
+  }
+  return stat;
+}
+void FileStats::apply_dialog_limit(int32 limit) {
+  if (limit == -1) {
+    return;
+  }
+  if (!split_by_owner_dialog_id) {
+    return;
+  }
+
+  std::vector<std::pair<int64, DialogId>> dialogs;
+  for (auto &dialog : stat_by_owner_dialog_id) {
+    if (!dialog.first.is_valid()) {
+      continue;
+    }
+    int64 size = 0;
+    for (auto &it : dialog.second) {
+      size += it.size;
+    }
+    dialogs.push_back(std::make_pair(size, dialog.first));
+  }
+  size_t prefix = dialogs.size();
+  if (prefix > static_cast<size_t>(limit)) {
+    prefix = static_cast<size_t>(limit);
+  }
+  std::partial_sort(dialogs.begin(), dialogs.begin() + prefix, dialogs.end(),
+                    [](const auto &x, const auto &y) { return x.first > y.first; });
+  dialogs.resize(prefix);
+
+  std::unordered_set<DialogId, DialogIdHash> all_dialogs;
+
+  for (auto &dialog : dialogs) {
+    all_dialogs.insert(dialog.second);
+  }
+
+  StatByType other_stats;
+  bool other_flag = false;
+  for (auto it = stat_by_owner_dialog_id.begin(); it != stat_by_owner_dialog_id.end();) {
+    if (all_dialogs.count(it->first)) {
+      it++;
+    } else {
+      for (size_t i = 0; i < file_type_size; i++) {
+        other_stats[i].size += it->second[i].size;
+        other_stats[i].cnt += it->second[i].cnt;
+      }
+      other_flag = true;
+      it = stat_by_owner_dialog_id.erase(it);
+    }
+  }
+
+  if (other_flag) {
+    DialogId other_dialog_id;
+    stat_by_owner_dialog_id[other_dialog_id] = other_stats;
+  }
+}
+
+tl_object_ptr<td_api::storageStatisticsByChat> as_td_api(DialogId dialog_id,
+                                                         const FileStats::StatByType &stat_by_type) {
+  auto stats = make_tl_object<td_api::storageStatisticsByChat>(dialog_id.get(), 0, 0, Auto());
+  for (size_t i = 0; i < file_type_size; i++) {
+    if (stat_by_type[i].size == 0) {
+      continue;
+    }
+    stats->size_ += stat_by_type[i].size;
+    stats->count_ += stat_by_type[i].cnt;
+    stats->by_file_type_.push_back(make_tl_object<td_api::storageStatisticsByFileType>(
+        as_td_api(FileType(i)), stat_by_type[i].size, stat_by_type[i].cnt));
+  }
+  return stats;
+}
+
+tl_object_ptr<td_api::storageStatistics> FileStats::as_td_api() const {
+  auto stats = make_tl_object<td_api::storageStatistics>(0, 0, Auto());
+  if (!split_by_owner_dialog_id) {
+    stats->by_chat_.reserve(1);
+    stats->by_chat_.push_back(::td::as_td_api(DialogId(), stat_by_type));
+  } else {
+    stats->by_chat_.reserve(stat_by_owner_dialog_id.size());
+    for (auto &by_dialog : stat_by_owner_dialog_id) {
+      stats->by_chat_.push_back(::td::as_td_api(by_dialog.first, by_dialog.second));
+    }
+    std::sort(stats->by_chat_.begin(), stats->by_chat_.end(), [](const auto &x, const auto &y) {
+      if (x->chat_id_ == 0 || y->chat_id_ == 0) {
+        return (x->chat_id_ == 0) < (y->chat_id_ == 0);
+      }
+      return x->size_ > y->size_;
+    });
+  }
+  for (const auto &by_dialog : stats->by_chat_) {
+    stats->size_ += by_dialog->size_;
+    stats->count_ += by_dialog->count_;
+  }
+  return stats;
+}
+
+std::vector<DialogId> FileStats::get_dialog_ids() const {
+  std::vector<DialogId> res;
+  if (!split_by_owner_dialog_id) {
+    return res;
+  }
+  res.reserve(stat_by_owner_dialog_id.size());
+  for (auto &by_dialog : stat_by_owner_dialog_id) {
+    if (by_dialog.first.is_valid()) {
+      res.push_back(by_dialog.first);
+    }
+  }
+  return res;
+}
+
+StringBuilder &operator<<(StringBuilder &sb, const FileTypeStat &stat) {
+  return sb << tag("size", format::as_size(stat.size)) << tag("count", stat.cnt);
+}
+
+StringBuilder &operator<<(StringBuilder &sb, const FileStats &file_stats) {
+  if (!file_stats.split_by_owner_dialog_id) {
+    FileTypeStat total_stat;
+    for (auto &type_stat : file_stats.stat_by_type) {
+      total_stat.size += type_stat.size;
+      total_stat.cnt += type_stat.cnt;
+    }
+
+    sb << "[FileStat " << tag("total", total_stat);
+    for (int i = 0; i < file_type_size; i++) {
+      sb << tag(Slice(file_type_name[i]), file_stats.stat_by_type[i]);
+    }
+    sb << "]";
+  } else {
+    {
+      FileTypeStat total_stat;
+      for (auto &by_type : file_stats.stat_by_owner_dialog_id) {
+        for (auto &type_stat : by_type.second) {
+          total_stat.size += type_stat.size;
+          total_stat.cnt += type_stat.cnt;
+        }
+      }
+      sb << "[FileStat " << tag("total", total_stat);
+    }
+    for (auto &by_type : file_stats.stat_by_owner_dialog_id) {
+      FileTypeStat dialog_stat;
+      for (auto &type_stat : by_type.second) {
+        dialog_stat.size += type_stat.size;
+        dialog_stat.cnt += type_stat.cnt;
+      }
+
+      sb << "[FileStat " << tag("owner_dialog_id", by_type.first) << tag("total", dialog_stat);
+      for (int i = 0; i < file_type_size; i++) {
+        sb << tag(Slice(file_type_name[i]), by_type.second[i]);
+      }
+      sb << "]";
+    }
+    sb << "]";
+  }
+
+  return sb;
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileStats.h b/libs/tdlib/td/td/telegram/files/FileStats.h
new file mode 100644
index 0000000000..5e02fd249e
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileStats.h
@@ -0,0 +1,88 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/DialogId.h"
+#include "td/telegram/files/FileLocation.h"
+
+#include "td/utils/common.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tl_helpers.h"
+
+#include <array>
+#include <unordered_map>
+
+namespace td {
+namespace td_api {
+class storageStatistics;
+class storageStatisticsFast;
+}  // namespace td_api
+}  // namespace td
+
+namespace td {
+
+struct FileTypeStat {
+  int64 size{0};
+  int32 cnt{0};
+};
+
+template <class T>
+void store(const FileTypeStat &stat, T &storer) {
+  using ::td::store;
+  store(stat.size, storer);
+  store(stat.cnt, storer);
+}
+template <class T>
+void parse(FileTypeStat &stat, T &parser) {
+  using ::td::parse;
+  parse(stat.size, parser);
+  parse(stat.cnt, parser);
+}
+
+struct FullFileInfo {
+  FileType file_type;
+  string path;
+  DialogId owner_dialog_id;
+  int64 size;
+  uint64 atime_nsec;
+  uint64 mtime_nsec;
+};
+
+struct FileStatsFast {
+  int64 size{0};
+  int32 count{0};
+  int64 db_size{0};
+  FileStatsFast(int64 size, int32 count, int64 db_size) : size(size), count(count), db_size(db_size) {
+  }
+  tl_object_ptr<td_api::storageStatisticsFast> as_td_api() const;
+};
+
+struct FileStats {
+  bool need_all_files{false};
+  bool split_by_owner_dialog_id{false};
+
+  using StatByType = std::array<FileTypeStat, file_type_size>;
+
+  StatByType stat_by_type;
+  std::unordered_map<DialogId, StatByType, DialogIdHash> stat_by_owner_dialog_id;
+
+  std::vector<FullFileInfo> all_files;
+
+  void add(FullFileInfo &&info);
+  void apply_dialog_limit(int32 limit);
+
+  tl_object_ptr<td_api::storageStatistics> as_td_api() const;
+  std::vector<DialogId> get_dialog_ids() const;
+  FileTypeStat get_total_nontemp_stat() const;
+
+ private:
+  void add(StatByType &by_type, FileType file_type, int64 size);
+};
+
+StringBuilder &operator<<(StringBuilder &sb, const FileStats &file_stats);
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileStatsWorker.cpp b/libs/tdlib/td/td/telegram/files/FileStatsWorker.cpp
new file mode 100644
index 0000000000..999402ae2b
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileStatsWorker.cpp
@@ -0,0 +1,184 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/files/FileStatsWorker.h"
+
+#include "td/telegram/DialogId.h"
+#include "td/telegram/files/FileDb.h"
+#include "td/telegram/files/FileLoaderUtils.h"
+#include "td/telegram/Global.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/PathView.h"
+#include "td/utils/port/path.h"
+#include "td/utils/port/Stat.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/Time.h"
+#include "td/utils/tl_helpers.h"
+
+#include <functional>
+#include <unordered_map>
+
+namespace td {
+namespace {
+// Performance ideas:
+// - use slice instead of string
+// - use arena memory allocator
+// - store FileType or dir, no both
+// - store dir relative to G()->files_dir()
+
+struct DbFileInfo {
+  FileType file_type;
+  string path;
+  DialogId owner_dialog_id;
+  int64 size;
+};
+
+// long and blocking
+template <class CallbackT>
+Status scan_db(CallbackT &&callback) {
+  G()->td_db()->get_file_db_shared()->pmc().get_by_range("file0", "file:", [&](Slice key, Slice value) {
+    // skip reference to other data
+    if (value.substr(0, 2) == "@@") {
+      return;
+    }
+    FileData data;
+    auto status = unserialize(data, value);
+    if (status.is_error()) {
+      LOG(ERROR) << "Invalid FileData in the database " << tag("value", format::escaped(value));
+      return;
+    }
+    DbFileInfo info;
+    if (data.local_.type() == LocalFileLocation::Type::Full) {
+      info.file_type = data.local_.full().file_type_;
+      info.path = data.local_.full().path_;
+    } else if (data.local_.type() == LocalFileLocation::Type::Partial) {
+      info.file_type = data.local_.partial().file_type_;
+      info.path = data.local_.partial().path_;
+    } else {
+      return;
+    }
+    PathView path_view(info.path);
+    if (path_view.is_relative()) {
+      info.path = get_files_base_dir(info.file_type) + info.path;
+    }
+    // LOG(INFO) << "Found file in the database: " << data << " " << info.path;
+    info.owner_dialog_id = data.owner_dialog_id_;
+    info.size = data.size_;
+    if (info.size == 0 && data.local_.type() == LocalFileLocation::Type::Full) {
+      LOG(ERROR) << "Unknown size in the database";
+      return;
+    }
+    callback(info);
+  });
+  return Status::OK();
+}
+
+struct FsFileInfo {
+  FileType file_type;
+  string path;
+  int64 size;
+  uint64 atime_nsec;
+  uint64 mtime_nsec;
+};
+
+// long and blocking
+template <class CallbackT>
+Status scan_fs(CallbackT &&callback) {
+  for (int i = 0; i < file_type_size; i++) {
+    auto file_type = static_cast<FileType>(i);
+    auto files_dir = get_files_dir(file_type);
+    td::walk_path(files_dir, [&](CSlice path, bool is_dir) {
+      if (is_dir) {
+        // TODO: skip subdirs
+        return;
+      }
+      auto r_stat = stat(path);
+      if (r_stat.is_error()) {
+        LOG(WARNING) << "Stat in files gc failed: " << r_stat.error();
+        return;
+      }
+      auto stat = r_stat.move_as_ok();
+      FsFileInfo info;
+      info.path = path.str();
+      info.size = stat.size_;
+      info.file_type = file_type;
+      info.atime_nsec = stat.atime_nsec_;
+      info.mtime_nsec = stat.mtime_nsec_;
+      callback(info);
+    });
+  }
+  return Status::OK();
+}
+}  // namespace
+
+void FileStatsWorker::get_stats(bool need_all_files, bool split_by_owner_dialog_id, Promise<FileStats> promise) {
+  if (!G()->parameters().use_chat_info_db) {
+    split_by_owner_dialog_id = false;
+  }
+  if (!split_by_owner_dialog_id) {
+    FileStats file_stats;
+    file_stats.need_all_files = need_all_files;
+    auto start = Time::now();
+    scan_fs([&](FsFileInfo &fs_info) {
+      FullFileInfo info;
+      info.file_type = fs_info.file_type;
+      info.path = std::move(fs_info.path);
+      info.size = fs_info.size;
+      info.atime_nsec = fs_info.atime_nsec;
+      info.mtime_nsec = fs_info.mtime_nsec;
+      file_stats.add(std::move(info));
+    });
+    auto passed = Time::now() - start;
+    LOG_IF(INFO, passed > 0.5) << "Get file stats took: " << format::as_time(passed);
+    promise.set_value(std::move(file_stats));
+  } else {
+    auto start = Time::now();
+
+    std::vector<FullFileInfo> full_infos;
+    scan_fs([&](FsFileInfo &fs_info) {
+      FullFileInfo info;
+      info.file_type = fs_info.file_type;
+      info.path = std::move(fs_info.path);
+      info.size = fs_info.size;
+      info.atime_nsec = fs_info.atime_nsec;
+      info.mtime_nsec = fs_info.mtime_nsec;
+
+      // LOG(INFO) << "Found file of size " << info.size << " at " << info.path;
+
+      full_infos.push_back(std::move(info));
+    });
+
+    std::unordered_map<size_t, size_t> hash_to_pos;
+    size_t pos = 0;
+    for (auto &full_info : full_infos) {
+      hash_to_pos[std::hash<std::string>()(full_info.path)] = pos;
+      pos++;
+    }
+    scan_db([&](DbFileInfo &db_info) {
+      auto it = hash_to_pos.find(std::hash<std::string>()(db_info.path));
+      if (it == hash_to_pos.end()) {
+        return;
+      }
+      // LOG(INFO) << "Match! " << db_info.path << " from " << db_info.owner_dialog_id;
+      full_infos[it->second].owner_dialog_id = db_info.owner_dialog_id;
+    });
+
+    FileStats file_stats;
+    file_stats.need_all_files = need_all_files;
+    file_stats.split_by_owner_dialog_id = split_by_owner_dialog_id;
+    for (auto &full_info : full_infos) {
+      file_stats.add(std::move(full_info));
+    }
+    auto passed = Time::now() - start;
+    LOG_IF(INFO, passed > 0.5) << "Get file stats took: " << format::as_time(passed);
+    promise.set_value(std::move(file_stats));
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileStatsWorker.h b/libs/tdlib/td/td/telegram/files/FileStatsWorker.h
new file mode 100644
index 0000000000..f70fcac1e0
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileStatsWorker.h
@@ -0,0 +1,26 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/files/FileStats.h"
+
+namespace td {
+
+class FileStatsWorker : public Actor {
+ public:
+  explicit FileStatsWorker(ActorShared<> parent) : parent_(std::move(parent)) {
+  }
+  void get_stats(bool need_all_files, bool split_by_owner_dialog_id, Promise<FileStats> promise);
+
+ private:
+  ActorShared<> parent_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileUploader.cpp b/libs/tdlib/td/td/telegram/files/FileUploader.cpp
new file mode 100644
index 0000000000..635e5c8933
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileUploader.cpp
@@ -0,0 +1,292 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/files/FileUploader.h"
+
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/Global.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/crypto.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Random.h"
+#include "td/utils/ScopeGuard.h"
+
+namespace td {
+FileUploader::FileUploader(const LocalFileLocation &local, const RemoteFileLocation &remote, int64 expected_size,
+                           const FileEncryptionKey &encryption_key, std::vector<int> bad_parts,
+                           std::unique_ptr<Callback> callback)
+    : local_(local)
+    , remote_(remote)
+    , expected_size_(expected_size)
+    , encryption_key_(encryption_key)
+    , bad_parts_(std::move(bad_parts))
+    , callback_(std::move(callback)) {
+  if (!encryption_key_.empty()) {
+    iv_ = encryption_key_.mutable_iv();
+    generate_iv_ = encryption_key_.iv_slice().str();
+  }
+}
+
+Result<FileLoader::FileInfo> FileUploader::init() {
+  if (remote_.type() == RemoteFileLocation::Type::Full) {
+    return Status::Error("File is already uploaded");
+  }
+
+  TRY_RESULT(prefix_info, on_update_local_location(local_));
+  (void)prefix_info;
+
+  int offset = 0;
+  int part_size = 0;
+  if (remote_.type() == RemoteFileLocation::Type::Partial) {
+    const auto &partial = remote_.partial();
+    file_id_ = partial.file_id_;
+    part_size = partial.part_size_;
+    big_flag_ = partial.is_big_ != 0;
+    offset = partial.ready_part_count_;
+  } else {
+    file_id_ = Random::secure_int64();
+    big_flag_ = expected_size_ > 10 * (1 << 20);
+  }
+
+  std::vector<bool> ok(offset, true);
+  for (auto bad_id : bad_parts_) {
+    if (bad_id >= 0 && bad_id < offset) {
+      ok[bad_id] = false;
+    }
+  }
+  std::vector<int> parts;
+  for (int i = 0; i < offset; i++) {
+    if (ok[i]) {
+      parts.push_back(i);
+    }
+  }
+  if (!ok.empty() && !ok[0]) {
+    parts.clear();
+  }
+  FileInfo res;
+  res.size = local_size_;
+  res.is_size_final = local_is_ready_;
+  res.part_size = part_size;
+  res.ready_parts = std::move(parts);
+  return res;
+}
+
+Result<FileLoader::PrefixInfo> FileUploader::on_update_local_location(const LocalFileLocation &location) {
+  SCOPE_EXIT {
+    try_release_fd();
+  };
+  string path;
+  int64 local_size = 0;
+  bool local_is_ready{false};
+  FileType file_type{FileType::Temp};
+  if (location.type() == LocalFileLocation::Type::Empty) {
+    path = "";
+    local_size = 0;
+    local_is_ready = false;
+    file_type = FileType::Temp;
+  } else if (location.type() == LocalFileLocation::Type::Partial) {
+    path = location.partial().path_;
+    local_size = static_cast<int64>(location.partial().part_size_) * location.partial().ready_part_count_;
+    local_is_ready = false;
+    file_type = location.partial().file_type_;
+  } else {
+    path = location.full().path_;
+    local_is_ready = true;
+    file_type = location.full().file_type_;
+  }
+
+  if (!path.empty() && path != fd_path_) {
+    auto res_fd = FileFd::open(path, FileFd::Read);
+
+    // Race: partial location could be already deleted. Just ignore such locations
+    if (res_fd.is_error()) {
+      if (location.type() == LocalFileLocation::Type::Partial) {
+        PrefixInfo info;
+        info.size = local_size_;
+        info.is_ready = local_is_ready_;
+        return info;
+      }
+      return res_fd.move_as_error();
+    }
+
+    fd_.close();
+    fd_ = res_fd.move_as_ok();
+    fd_path_ = path;
+  }
+
+  if (local_is_ready) {
+    CHECK(!fd_.empty());
+    local_size = fd_.get_size();
+    if (local_size == 0) {
+      return Status::Error("Can't upload empty file");
+    }
+  } else if (!fd_.empty()) {
+    auto real_local_size = fd_.get_size();
+    if (real_local_size < local_size) {
+      LOG(ERROR) << tag("real_local_size", real_local_size) << " < " << tag("local_size", local_size);
+      PrefixInfo info;
+      info.size = local_size_;
+      info.is_ready = local_is_ready_;
+      return info;
+    }
+  }
+
+  local_size_ = local_size;
+  if (expected_size_ < local_size_) {
+    expected_size_ = local_size_;
+  }
+  local_is_ready_ = local_is_ready;
+  file_type_ = file_type;
+
+  PrefixInfo info;
+  info.size = local_size_;
+  info.is_ready = local_is_ready_;
+  return info;
+}
+
+Status FileUploader::on_ok(int64 size) {
+  fd_.close();
+  return Status::OK();
+}
+void FileUploader::on_error(Status status) {
+  fd_.close();
+  callback_->on_error(std::move(status));
+}
+
+Status FileUploader::generate_iv_map() {
+  LOG(INFO) << "generate iv_map " << generate_offset_ << " " << local_size_;
+  auto part_size = get_part_size();
+  auto encryption_key = FileEncryptionKey(encryption_key_.key_slice(), generate_iv_);
+  BufferSlice bytes(part_size);
+  if (iv_map_.empty()) {
+    iv_map_.push_back(encryption_key.mutable_iv());
+  }
+  CHECK(!fd_.empty());
+  for (; generate_offset_ + static_cast<int64>(part_size) < local_size_;
+       generate_offset_ += static_cast<int64>(part_size)) {
+    TRY_RESULT(read_size, fd_.pread(bytes.as_slice(), generate_offset_));
+    if (read_size != part_size) {
+      return Status::Error("Failed to read file part (for iv_map)");
+    }
+    aes_ige_encrypt(encryption_key.key(), &encryption_key.mutable_iv(), bytes.as_slice(), bytes.as_slice());
+    iv_map_.push_back(encryption_key.mutable_iv());
+  }
+  generate_iv_ = encryption_key.iv_slice().str();
+  return Status::OK();
+}
+
+Status FileUploader::before_start_parts() {
+  auto status = acquire_fd();
+  if (status.is_error() && !local_is_ready_) {
+    return Status::Error(1, "Can't open temporary file");
+  }
+  return status;
+}
+void FileUploader::after_start_parts() {
+  try_release_fd();
+}
+
+Result<std::pair<NetQueryPtr, bool>> FileUploader::start_part(Part part, int32 part_count) {
+  auto padded_size = part.size;
+  if (!encryption_key_.empty()) {
+    padded_size = (padded_size + 15) & ~15;
+  }
+  BufferSlice bytes(padded_size);
+  TRY_RESULT(size, fd_.pread(bytes.as_slice().truncate(part.size), part.offset));
+  if (!encryption_key_.empty()) {
+    Random::secure_bytes(bytes.as_slice().substr(part.size));
+    if (next_offset_ == part.offset) {
+      aes_ige_encrypt(encryption_key_.key(), &iv_, bytes.as_slice(), bytes.as_slice());
+      next_offset_ += static_cast<int64>(bytes.size());
+    } else {
+      if (part.id >= static_cast<int32>(iv_map_.size())) {
+        TRY_STATUS(generate_iv_map());
+      }
+      CHECK(part.id < static_cast<int32>(iv_map_.size()) && part.id >= 0);
+      auto iv = iv_map_[part.id];
+      aes_ige_encrypt(encryption_key_.key(), &iv, bytes.as_slice(), bytes.as_slice());
+    }
+  }
+
+  if (size != part.size) {
+    LOG(ERROR) << "Need to read " << part.size << " bytes, but read " << size << " bytes instead";
+    return Status::Error("Failed to read file part");
+  }
+
+  NetQueryPtr net_query;
+  if (big_flag_) {
+    auto query =
+        telegram_api::upload_saveBigFilePart(file_id_, part.id, local_is_ready_ ? part_count : -1, std::move(bytes));
+    net_query = G()->net_query_creator().create(create_storer(query), DcId::main(), NetQuery::Type::Upload,
+                                                NetQuery::AuthFlag::On, NetQuery::GzipFlag::Off);
+  } else {
+    auto query = telegram_api::upload_saveFilePart(file_id_, part.id, std::move(bytes));
+    net_query = G()->net_query_creator().create(create_storer(query), DcId::main(), NetQuery::Type::Upload,
+                                                NetQuery::AuthFlag::On, NetQuery::GzipFlag::Off);
+  }
+  net_query->file_type_ = narrow_cast<int32>(file_type_);
+  return std::make_pair(std::move(net_query), false);
+}
+
+Result<size_t> FileUploader::process_part(Part part, NetQueryPtr net_query) {
+  if (net_query->is_error()) {
+    return std::move(net_query->error());
+  }
+  Result<bool> result;
+  if (big_flag_) {
+    result = fetch_result<telegram_api::upload_saveBigFilePart>(net_query->ok());
+  } else {
+    result = fetch_result<telegram_api::upload_saveFilePart>(net_query->ok());
+  }
+  if (result.is_error()) {
+    return result.move_as_error();
+  }
+  if (!result.ok()) {
+    // TODO: it is possible
+    return Status::Error(500, "Internal Server Error");
+  }
+  return part.size;
+}
+
+void FileUploader::on_progress(int32 part_count, int32 part_size, int32 ready_part_count, bool is_ready,
+                               int64 ready_size) {
+  callback_->on_partial_upload(PartialRemoteFileLocation{file_id_, part_count, part_size, ready_part_count, big_flag_},
+                               ready_size);
+  if (is_ready) {
+    callback_->on_ok(file_type_,
+                     PartialRemoteFileLocation{file_id_, part_count, part_size, ready_part_count, big_flag_},
+                     local_size_);
+  }
+}
+FileLoader::Callback *FileUploader::get_callback() {
+  return static_cast<FileLoader::Callback *>(callback_.get());
+}
+
+void FileUploader::keep_fd_flag(bool keep_fd) {
+  keep_fd_ = keep_fd;
+  try_release_fd();
+}
+
+void FileUploader::try_release_fd() {
+  if (!keep_fd_ && !fd_.empty()) {
+    fd_.close();
+  }
+}
+
+Status FileUploader::acquire_fd() {
+  if (fd_.empty()) {
+    TRY_RESULT(fd, FileFd::open(fd_path_, FileFd::Read));
+    fd_ = std::move(fd);
+  }
+  return Status::OK();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/FileUploader.h b/libs/tdlib/td/td/telegram/files/FileUploader.h
new file mode 100644
index 0000000000..7f2ccfe8e8
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/FileUploader.h
@@ -0,0 +1,76 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/files/FileLoader.h"
+#include "td/telegram/files/FileLocation.h"
+
+#include "td/utils/port/FileFd.h"
+#include "td/utils/Status.h"
+
+#include <utility>
+
+namespace td {
+class FileUploader : public FileLoader {
+ public:
+  class Callback : public FileLoader::Callback {
+   public:
+    virtual void on_partial_upload(const PartialRemoteFileLocation &partial_remote, int64 ready_size) = 0;
+    virtual void on_ok(FileType file_type, const PartialRemoteFileLocation &partial_remote, int64 size) = 0;
+    virtual void on_error(Status status) = 0;
+  };
+
+  FileUploader(const LocalFileLocation &local, const RemoteFileLocation &remote, int64 expected_size,
+               const FileEncryptionKey &encryption_key, std::vector<int> bad_parts, std::unique_ptr<Callback> callback);
+
+  // Should just implement all parent pure virtual methods.
+  // Must not call any of them...
+ private:
+  ResourceState resource_state_;
+  LocalFileLocation local_;
+  RemoteFileLocation remote_;
+  int64 expected_size_;
+  FileEncryptionKey encryption_key_;
+  std::vector<int> bad_parts_;
+  std::unique_ptr<Callback> callback_;
+  int64 local_size_ = 0;
+  bool local_is_ready_ = false;
+  FileType file_type_ = FileType::Temp;
+
+  std::vector<UInt256> iv_map_;
+  UInt256 iv_;
+  string generate_iv_;
+  int64 generate_offset_ = 0;
+  int64 next_offset_ = 0;
+
+  FileFd fd_;
+  string fd_path_;
+  int64 file_id_;
+  bool big_flag_;
+
+  Result<FileInfo> init() override TD_WARN_UNUSED_RESULT;
+  Status on_ok(int64 size) override TD_WARN_UNUSED_RESULT;
+  void on_error(Status status) override;
+  Status before_start_parts() override;
+  void after_start_parts() override;
+  Result<std::pair<NetQueryPtr, bool>> start_part(Part part, int32 part_count) override TD_WARN_UNUSED_RESULT;
+  Result<size_t> process_part(Part part, NetQueryPtr net_query) override TD_WARN_UNUSED_RESULT;
+  void on_progress(int32 part_count, int32 part_size, int32 ready_part_count, bool is_ready, int64 ready_size) override;
+  FileLoader::Callback *get_callback() override;
+  Result<PrefixInfo> on_update_local_location(const LocalFileLocation &location) override TD_WARN_UNUSED_RESULT;
+
+  Status generate_iv_map();
+
+  bool keep_fd_ = false;
+  void keep_fd_flag(bool keep_fd) override;
+  void try_release_fd();
+  Status acquire_fd() TD_WARN_UNUSED_RESULT;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/PartsManager.cpp b/libs/tdlib/td/td/telegram/files/PartsManager.cpp
new file mode 100644
index 0000000000..75debb7af1
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/PartsManager.cpp
@@ -0,0 +1,333 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/files/PartsManager.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+
+#include <limits>
+#include <numeric>
+
+namespace td {
+/*** PartsManager ***/
+
+namespace {
+int64 calc_parts_count(int64 size, int64 part_size) {
+  CHECK(part_size != 0);
+  return (size + part_size - 1) / part_size;
+}
+}  // namespace
+
+Status PartsManager::init_known_prefix(int64 known_prefix, size_t part_size, const std::vector<int> &ready_parts) {
+  known_prefix_flag_ = true;
+  known_prefix_size_ = known_prefix;
+  return init_no_size(part_size, ready_parts);
+}
+
+Status PartsManager::init_no_size(size_t part_size, const std::vector<int> &ready_parts) {
+  unknown_size_flag_ = true;
+  size_ = 0;
+  min_size_ = 0;
+  max_size_ = std::numeric_limits<int64>::max();
+
+  if (part_size != 0) {
+    part_size_ = part_size;
+  } else {
+    part_size_ = 32 * (1 << 10);
+    while (use_part_count_limit_ && calc_parts_count(expected_size_, part_size_) > MAX_PART_COUNT) {
+      part_size_ *= 2;
+      CHECK(part_size_ <= MAX_PART_SIZE);
+    }
+    // just in case if expected_size_ is wrong
+    if (part_size_ < MAX_PART_SIZE) {
+      part_size_ *= 2;
+    }
+  }
+  part_count_ = 0;
+  if (known_prefix_flag_) {
+    part_count_ = static_cast<int>(known_prefix_size_ / part_size_);
+  }
+  part_count_ = max(part_count_, std::accumulate(ready_parts.begin(), ready_parts.end(), 0,
+                                                 [](auto a, auto b) { return max(a, b + 1); }));
+
+  init_common(ready_parts);
+  return Status::OK();
+}
+
+Status PartsManager::init(int64 size, int64 expected_size, bool is_size_final, size_t part_size,
+                          const std::vector<int> &ready_parts, bool use_part_count_limit) {
+  CHECK(expected_size >= size);
+  use_part_count_limit_ = use_part_count_limit;
+  expected_size_ = expected_size;
+  if (expected_size_ > MAX_FILE_SIZE) {
+    return Status::Error("Too big file");
+  }
+  if (!is_size_final) {
+    return init_known_prefix(size, part_size, ready_parts);
+  }
+  if (size == 0) {
+    return init_no_size(part_size, ready_parts);
+  }
+  CHECK(size > 0) << tag("size", size);
+  unknown_size_flag_ = false;
+  size_ = size;
+
+  if (part_size != 0) {
+    part_size_ = part_size;
+    if (use_part_count_limit_ && calc_parts_count(expected_size_, part_size_) > MAX_PART_COUNT) {
+      return Status::Error("FILE_UPLOAD_RESTART");
+    }
+  } else {
+    // TODO choose part_size_ depending on size
+    part_size_ = 64 * (1 << 10);
+    while (use_part_count_limit && calc_parts_count(expected_size_, part_size_) > MAX_PART_COUNT) {
+      part_size_ *= 2;
+      CHECK(part_size_ <= MAX_PART_SIZE);
+    }
+  }
+  CHECK(1 <= size_) << tag("size_", size_);
+  CHECK(!use_part_count_limit || calc_parts_count(expected_size_, part_size_) <= MAX_PART_COUNT)
+      << tag("size_", size_) << tag("expected_size", size_) << tag("is_size_final", is_size_final)
+      << tag("part_size_", part_size_) << tag("ready_parts", ready_parts.size());
+  part_count_ = static_cast<int>(calc_parts_count(size_, part_size_));
+
+  init_common(ready_parts);
+  return Status::OK();
+}
+
+bool PartsManager::unchecked_ready() {
+  VLOG(files) << "Check readiness. Ready size is " << ready_size_ << ", total size is " << size_
+              << ", unknown_size_flag = " << unknown_size_flag_ << ", need_check = " << need_check_
+              << ", checked_prefix_size = " << checked_prefix_size_;
+  return !unknown_size_flag_ && ready_size_ == size_;
+}
+bool PartsManager::ready() {
+  return unchecked_ready() && (!need_check_ || checked_prefix_size_ == size_);
+}
+
+Status PartsManager::finish() {
+  if (!ready()) {
+    return Status::Error("File transferring not finished");
+  }
+  return Status::OK();
+}
+
+void PartsManager::update_first_empty_part() {
+  while (first_empty_part_ < part_count_ && part_status_[first_empty_part_] != PartStatus::Empty) {
+    first_empty_part_++;
+  }
+}
+
+void PartsManager::update_first_not_ready_part() {
+  while (first_not_ready_part_ < part_count_ && part_status_[first_not_ready_part_] == PartStatus::Ready) {
+    first_not_ready_part_++;
+  }
+}
+
+int32 PartsManager::get_ready_prefix_count() {
+  update_first_not_ready_part();
+  auto res = first_not_ready_part_;
+  if (need_check_) {
+    auto checked_parts = narrow_cast<int32>(checked_prefix_size_ / part_size_);
+    if (checked_parts < res) {
+      res = checked_parts;
+    }
+  }
+  return res;
+}
+
+Result<Part> PartsManager::start_part() {
+  update_first_empty_part();
+  if (first_empty_part_ == part_count_) {
+    if (unknown_size_flag_) {
+      if (known_prefix_flag_ == false) {
+        part_count_++;
+        if (part_count_ > MAX_PART_COUNT) {
+          return Status::Error("Too big file with unknown size");
+        }
+        part_status_.push_back(PartStatus::Empty);
+      } else {
+        return Status::Error(1, "Wait for prefix to be known");
+      }
+    } else {
+      return get_empty_part();
+    }
+  }
+  CHECK(part_status_[first_empty_part_] == PartStatus::Empty);
+  int id = first_empty_part_;
+  on_part_start(id);
+  return get_part(id);
+}
+
+Status PartsManager::set_known_prefix(size_t size, bool is_ready) {
+  CHECK(known_prefix_flag_);
+  CHECK(size >= static_cast<size_t>(known_prefix_size_));
+  known_prefix_size_ = narrow_cast<int64>(size);
+  expected_size_ = max(known_prefix_size_, expected_size_);
+
+  CHECK(static_cast<size_t>(part_count_) == part_status_.size());
+  if (is_ready) {
+    part_count_ = static_cast<int>(calc_parts_count(size, part_size_));
+
+    size_ = narrow_cast<int64>(size);
+    unknown_size_flag_ = false;
+  } else {
+    part_count_ = static_cast<int>(size / part_size_);
+  }
+  CHECK(static_cast<size_t>(part_count_) >= part_status_.size())
+      << size << " " << is_ready << " " << part_count_ << " " << part_size_ << " " << part_status_.size();
+  part_status_.resize(part_count_);
+  if (use_part_count_limit_ && calc_parts_count(expected_size_, part_size_) > MAX_PART_COUNT) {
+    return Status::Error("FILE_UPLOAD_RESTART");
+  }
+  return Status::OK();
+}
+
+Status PartsManager::on_part_ok(int32 id, size_t part_size, size_t actual_size) {
+  CHECK(part_status_[id] == PartStatus::Pending);
+  pending_count_--;
+
+  part_status_[id] = PartStatus::Ready;
+  ready_size_ += narrow_cast<int64>(actual_size);
+
+  VLOG(files) << "Transferred part " << id << " of size " << part_size << ", total ready size = " << ready_size_;
+
+  int64 offset = narrow_cast<int64>(part_size_) * id;
+  int64 end_offset = offset + narrow_cast<int64>(actual_size);
+  if (unknown_size_flag_) {
+    CHECK(part_size == part_size_);
+    if (actual_size < part_size_) {
+      max_size_ = min(max_size_, end_offset);
+    }
+    if (actual_size) {
+      min_size_ = max(min_size_, end_offset);
+    }
+    if (min_size_ > max_size_) {
+      auto status = Status::Error(PSLICE() << "Failed to transfer file: " << tag("min_size", min_size_)
+                                           << tag("max_size", max_size_));
+      LOG(ERROR) << status;
+      return status;
+    } else if (min_size_ == max_size_) {
+      unknown_size_flag_ = false;
+      size_ = min_size_;
+    }
+  } else {
+    if ((actual_size < part_size && offset < size_) || (offset >= size_ && actual_size > 0)) {
+      auto status = Status::Error(PSLICE() << "Failed to transfer file: " << tag("size", size_) << tag("offset", offset)
+                                           << tag("transferred size", actual_size) << tag("part size", part_size));
+      LOG(ERROR) << status;
+      return status;
+    }
+  }
+  return Status::OK();
+}
+
+void PartsManager::on_part_failed(int32 id) {
+  CHECK(part_status_[id] == PartStatus::Pending);
+  pending_count_--;
+  part_status_[id] = PartStatus::Empty;
+  if (id < first_empty_part_) {
+    first_empty_part_ = id;
+  }
+}
+
+int64 PartsManager::get_size() const {
+  CHECK(!unknown_size_flag_);
+  return size_;
+}
+int64 PartsManager::get_size_or_zero() const {
+  return size_;
+}
+
+int64 PartsManager::get_ready_size() const {
+  return ready_size_;
+}
+
+int64 PartsManager::get_expected_size() const {
+  if (unknown_size_flag_) {
+    return max(static_cast<int64>(512 * (1 << 10)), get_ready_size() * 2);
+  }
+  return get_size();
+}
+
+size_t PartsManager::get_part_size() const {
+  return part_size_;
+}
+
+int32 PartsManager::get_part_count() const {
+  return part_count_;
+}
+
+void PartsManager::init_common(const std::vector<int> &ready_parts) {
+  ready_size_ = 0;
+  pending_count_ = 0;
+  first_empty_part_ = 0;
+  first_not_ready_part_ = 0;
+  part_status_ = vector<PartStatus>(part_count_);
+
+  for (auto i : ready_parts) {
+    CHECK(0 <= i && i < part_count_) << tag("i", i) << tag("part_count", part_count_);
+    part_status_[i] = PartStatus::Ready;
+    auto part = get_part(i);
+    ready_size_ += narrow_cast<int64>(part.size);
+  }
+
+  checked_prefix_size_ = get_ready_prefix_count() * narrow_cast<int64>(part_size_);
+}
+
+void PartsManager::set_need_check() {
+  need_check_ = true;
+}
+
+void PartsManager::set_checked_prefix_size(int64 size) {
+  checked_prefix_size_ = size;
+}
+
+int64 PartsManager::get_checked_prefix_size() const {
+  return checked_prefix_size_;
+}
+int64 PartsManager::get_unchecked_ready_prefix_size() {
+  update_first_not_ready_part();
+  auto count = first_not_ready_part_;
+  if (count == 0) {
+    return 0;
+  }
+  auto part = get_part(count - 1);
+  int64 res = part.offset;
+  if (!unknown_size_flag_) {
+    res += narrow_cast<int64>(part.size);
+    res = min(res, get_size());
+  }
+  return res;
+}
+
+Part PartsManager::get_part(int id) {
+  int64 offset = narrow_cast<int64>(part_size_) * id;
+  int64 size = narrow_cast<int64>(part_size_);
+  if (!unknown_size_flag_) {
+    auto total_size = get_size();
+    if (total_size < offset) {
+      size = 0;
+    } else {
+      size = min(size, total_size - offset);
+    }
+  }
+  return Part{id, offset, static_cast<size_t>(size)};
+}
+
+Part PartsManager::get_empty_part() {
+  return Part{-1, 0, 0};
+}
+
+void PartsManager::on_part_start(int32 id) {
+  CHECK(part_status_[id] == PartStatus::Empty);
+  part_status_[id] = PartStatus::Pending;
+  pending_count_++;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/PartsManager.h b/libs/tdlib/td/td/telegram/files/PartsManager.h
new file mode 100644
index 0000000000..26c31d5174
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/PartsManager.h
@@ -0,0 +1,87 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+/*** PartsManager***/
+struct Part {
+  int id;
+  int64 offset;
+  size_t size;
+};
+
+class PartsManager {
+ public:
+  Status init(int64 size, int64 expected_size, bool is_size_final, size_t part_size,
+              const std::vector<int> &ready_parts, bool use_part_count_limit) TD_WARN_UNUSED_RESULT;
+  bool ready();
+  bool unchecked_ready();
+  Status finish() TD_WARN_UNUSED_RESULT;
+
+  // returns empty part if nothing to return
+  Result<Part> start_part() TD_WARN_UNUSED_RESULT;
+  Status on_part_ok(int32 id, size_t part_size, size_t actual_size) TD_WARN_UNUSED_RESULT;
+  void on_part_failed(int32 id);
+  Status set_known_prefix(size_t size, bool is_ready);
+  void set_need_check();
+  void set_checked_prefix_size(int64 size);
+
+  int64 get_checked_prefix_size() const;
+  int64 get_unchecked_ready_prefix_size();
+  int64 get_size() const;
+  int64 get_size_or_zero() const;
+  int64 get_expected_size() const;
+  int64 get_ready_size() const;
+  size_t get_part_size() const;
+  int32 get_part_count() const;
+  int32 get_ready_prefix_count();
+
+ private:
+  static constexpr int MAX_PART_COUNT = 3000;
+  static constexpr int MAX_PART_SIZE = 512 * (1 << 10);
+  static constexpr int64 MAX_FILE_SIZE = MAX_PART_SIZE * MAX_PART_COUNT;
+
+  enum class PartStatus { Empty, Pending, Ready };
+
+  bool need_check_{false};
+  int64 checked_prefix_size_{0};
+
+  bool known_prefix_flag_{false};
+  int64 known_prefix_size_;
+
+  int64 size_;
+  int64 expected_size_;
+  int64 min_size_;
+  int64 max_size_;
+  bool unknown_size_flag_;
+  int64 ready_size_;
+
+  size_t part_size_;
+  int part_count_;
+  int pending_count_;
+  int first_empty_part_;
+  int first_not_ready_part_;
+  vector<PartStatus> part_status_;
+  bool use_part_count_limit_;
+
+  void init_common(const vector<int> &ready_parts);
+  Status init_known_prefix(int64 known_prefix, size_t part_size,
+                           const std::vector<int> &ready_parts) TD_WARN_UNUSED_RESULT;
+  Status init_no_size(size_t part_size, const std::vector<int> &ready_parts) TD_WARN_UNUSED_RESULT;
+
+  Part get_part(int id);
+  Part get_empty_part();
+  void on_part_start(int32 id);
+  void update_first_empty_part();
+  void update_first_not_ready_part();
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/ResourceManager.cpp b/libs/tdlib/td/td/telegram/files/ResourceManager.cpp
new file mode 100644
index 0000000000..00677ddd76
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/ResourceManager.cpp
@@ -0,0 +1,179 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/files/ResourceManager.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/ScopeGuard.h"
+
+#include <algorithm>
+
+namespace td {
+
+void ResourceManager::register_worker(ActorShared<FileLoaderActor> callback, int8 priority) {
+  auto node_id = nodes_container_.create();
+  auto *node_ptr = nodes_container_.get(node_id);
+  *node_ptr = std::make_unique<Node>();
+  auto *node = (*node_ptr).get();
+  CHECK(node);
+  node->node_id = node_id;
+  node->callback_ = std::move(callback);
+
+  add_node(node_id, priority);
+  send_closure(node->callback_, &FileLoaderActor::set_resource_manager, actor_shared(this, node_id));
+}
+
+void ResourceManager::update_priority(int8 priority) {
+  if (stop_flag_) {
+    return;
+  }
+  auto node_id = get_link_token();
+  if (!remove_node(node_id)) {
+    return;
+  }
+  add_node(node_id, priority);
+}
+
+void ResourceManager::update_resources(const ResourceState &resource_state) {
+  if (stop_flag_) {
+    return;
+  }
+  auto node_id = get_link_token();
+  auto node_ptr = nodes_container_.get(node_id);
+  if (node_ptr == nullptr) {
+    return;
+  }
+  auto node = (*node_ptr).get();
+  CHECK(node);
+  VLOG(files) << "before total: " << resource_state_;
+  VLOG(files) << "before " << tag("node_id", node_id) << ": " << node->resource_state_;
+  resource_state_ -= node->resource_state_;
+  node->resource_state_.update_master(resource_state);
+  resource_state_ += node->resource_state_;
+  VLOG(files) << "after total: " << resource_state_;
+  VLOG(files) << "after " << tag("node_id", node_id) << ": " << node->resource_state_;
+
+  if (mode_ == Mode::Greedy) {
+    add_to_heap(node);
+  }
+  loop();
+}
+
+void ResourceManager::hangup_shared() {
+  auto node_id = get_link_token();
+  auto node_ptr = nodes_container_.get(node_id);
+  if (node_ptr == nullptr) {
+    return;
+  }
+  auto node = (*node_ptr).get();
+  CHECK(node);
+  if (node->in_heap()) {
+    by_estimated_extra_.erase(node->as_heap_node());
+  }
+  resource_state_ -= node->resource_state_;
+  remove_node(node_id);
+  nodes_container_.erase(node_id);
+  loop();
+}
+
+void ResourceManager::add_to_heap(Node *node) {
+  auto *heap_node = node->as_heap_node();
+  auto key = node->resource_state_.estimated_extra();
+  if (heap_node->in_heap()) {
+    if (key != 0) {
+      by_estimated_extra_.fix(key, heap_node);
+    } else {
+      by_estimated_extra_.erase(heap_node);
+    }
+  } else {
+    if (key != 0) {
+      by_estimated_extra_.insert(key, heap_node);
+    }
+  }
+}
+
+bool ResourceManager::satisfy_node(NodeId file_node_id) {
+  auto file_node_ptr = nodes_container_.get(file_node_id);
+  CHECK(file_node_ptr);
+  auto file_node = (*file_node_ptr).get();
+  CHECK(file_node);
+  auto part_size = narrow_cast<int64>(file_node->resource_state_.unit_size());
+  auto need = file_node->resource_state_.estimated_extra();
+  VLOG(files) << tag("need", need) << tag("part_size", part_size);
+  need = (need + part_size - 1) / part_size * part_size;
+  VLOG(files) << tag("need", need);
+  if (need == 0) {
+    return true;
+  }
+  auto give = resource_state_.unused();
+  give = min(need, give);
+  give -= give % part_size;
+  VLOG(files) << tag("give", give);
+  if (give == 0) {
+    return false;
+  }
+  resource_state_.start_use(give);
+  file_node->resource_state_.update_limit(give);
+  send_closure(file_node->callback_, &FileLoaderActor::update_resources, file_node->resource_state_);
+  return true;
+}
+
+void ResourceManager::loop() {
+  if (stop_flag_) {
+    if (nodes_container_.empty()) {
+      stop();
+    }
+    return;
+  }
+  auto active_limit = resource_state_.active_limit();
+  resource_state_.update_limit(2 * 1024 * (1 << 10) - active_limit);
+  LOG(INFO) << tag("unused", resource_state_.unused());
+
+  if (mode_ == Mode::Greedy) {
+    std::vector<Node *> to_add;
+    while (!by_estimated_extra_.empty()) {
+      auto *node = Node::from_heap_node(by_estimated_extra_.pop());
+      SCOPE_EXIT {
+        to_add.push_back(node);
+      };
+      if (!satisfy_node(node->node_id)) {
+        break;
+      }
+    }
+    for (auto *node : to_add) {
+      add_to_heap(node);
+    }
+  } else if (mode_ == Mode::Baseline) {
+    // plain
+    for (auto &it : to_xload_) {
+      auto file_node_id = it.second;
+      if (!satisfy_node(file_node_id)) {
+        break;
+      }
+    }
+  }
+}
+void ResourceManager::add_node(NodeId node_id, int8 priority) {
+  if (priority >= 0) {
+    auto it = std::find_if(to_xload_.begin(), to_xload_.end(), [&](auto &x) { return x.first <= priority; });
+    to_xload_.insert(it, std::make_pair(priority, node_id));
+  } else {
+    auto it = std::find_if(to_xload_.begin(), to_xload_.end(), [&](auto &x) { return x.first < -priority; });
+    to_xload_.insert(it, std::make_pair(-priority, node_id));
+  }
+}
+bool ResourceManager::remove_node(NodeId node_id) {
+  auto it = std::find_if(to_xload_.begin(), to_xload_.end(), [&](auto &x) { return x.second == node_id; });
+  if (it != to_xload_.end()) {
+    to_xload_.erase(it);
+    return true;
+  }
+  return false;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/ResourceManager.h b/libs/tdlib/td/td/telegram/files/ResourceManager.h
new file mode 100644
index 0000000000..48a32f18f6
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/ResourceManager.h
@@ -0,0 +1,66 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/files/FileLoaderActor.h"
+#include "td/telegram/files/ResourceState.h"
+
+#include "td/utils/Container.h"
+#include "td/utils/Heap.h"
+
+#include <utility>
+
+namespace td {
+class ResourceManager : public Actor {
+ public:
+  enum class Mode { Baseline, Greedy };
+  explicit ResourceManager(Mode mode) : mode_(mode) {
+  }
+  // use through ActorShared
+  void update_priority(int8 priority);
+  void update_resources(const ResourceState &resource_state);
+
+  void register_worker(ActorShared<FileLoaderActor> callback, int8 priority);
+
+ private:
+  Mode mode_;
+  using NodeId = uint64;
+  struct Node : public HeapNode {
+    NodeId node_id;
+
+    ResourceState resource_state_;
+    ActorShared<FileLoaderActor> callback_;
+
+    HeapNode *as_heap_node() {
+      return static_cast<HeapNode *>(this);
+    }
+    static Node *from_heap_node(HeapNode *heap_node) {
+      return static_cast<Node *>(heap_node);
+    }
+  };
+
+  Container<std::unique_ptr<Node>> nodes_container_;
+  vector<std::pair<int8, NodeId>> to_xload_;
+  KHeap<int64> by_estimated_extra_;
+  ResourceState resource_state_;
+
+  ActorShared<> parent_;
+  bool stop_flag_ = false;
+
+  void hangup_shared() override;
+
+  void loop() override;
+
+  void add_to_heap(Node *node);
+  bool satisfy_node(NodeId file_node_id);
+  void add_node(NodeId node_id, int8 priority);
+  bool remove_node(NodeId node_id);
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/files/ResourceState.h b/libs/tdlib/td/td/telegram/files/ResourceState.h
new file mode 100644
index 0000000000..e6a251ce95
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/files/ResourceState.h
@@ -0,0 +1,104 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/StringBuilder.h"
+
+namespace td {
+
+class ResourceState {
+ public:
+  void start_use(int64 x) {
+    using_ += x;
+    CHECK(used_ + using_ <= limit_);
+  }
+
+  void stop_use(int64 x) {
+    CHECK(x <= using_);
+    using_ -= x;
+    used_ += x;
+  }
+
+  void update_limit(int64 extra) {
+    limit_ += extra;
+  }
+
+  bool update_estimated_limit(int64 extra) {
+    auto new_estimated_limit = used_ + extra;
+    if (new_estimated_limit == estimated_limit_) {
+      return false;
+    }
+    estimated_limit_ = new_estimated_limit;
+    return true;
+  }
+
+  void set_unit_size(size_t new_unit_size) {
+    unit_size_ = new_unit_size;
+  }
+
+  int64 active_limit() const {
+    return limit_ - used_;
+  }
+
+  int64 get_using() const {
+    return using_;
+  }
+
+  int64 unused() const {
+    return limit_ - using_ - used_;
+  }
+
+  int64 estimated_extra() const {
+    auto new_unused = max(limit_, estimated_limit_) - using_ - used_;
+    new_unused = static_cast<int64>((new_unused + unit_size() - 1) / unit_size() * unit_size());
+    return new_unused + using_ + used_ - limit_;
+  }
+
+  size_t unit_size() const {
+    return unit_size_;
+  }
+
+  ResourceState &operator+=(const ResourceState &other) {
+    using_ += other.active_limit();
+    used_ += other.used_;
+    return *this;
+  }
+
+  ResourceState &operator-=(const ResourceState &other) {
+    using_ -= other.active_limit();
+    used_ -= other.used_;
+    return *this;
+  }
+
+  void update_master(const ResourceState &other) {
+    estimated_limit_ = other.estimated_limit_;
+    used_ = other.used_;
+    using_ = other.using_;
+    unit_size_ = other.unit_size_;
+  }
+
+  void update_slave(const ResourceState &other) {
+    limit_ = other.limit_;
+  }
+
+  friend StringBuilder &operator<<(StringBuilder &sb, const ResourceState &state) {
+    return sb << tag("estimated_limit", state.estimated_limit_) << tag("used", state.used_)
+              << tag("using", state.using_) << tag("limit", state.limit_);
+  }
+
+ private:
+  int64 estimated_limit_ = 0;  // me
+  int64 limit_ = 0;            // master
+  int64 used_ = 0;             // me
+  int64 using_ = 0;            // me
+  size_t unit_size_ = 1;       // me
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/logevent/LogEvent.h b/libs/tdlib/td/td/telegram/logevent/LogEvent.h
new file mode 100644
index 0000000000..9275c6faeb
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/logevent/LogEvent.h
@@ -0,0 +1,291 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/Global.h"
+#include "td/telegram/Version.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/Storer.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tl_helpers.h"
+#include "td/utils/tl_parsers.h"
+#include "td/utils/tl_storers.h"
+
+#include <type_traits>
+
+namespace td {
+namespace logevent {
+
+template <class ParentT>
+class WithVersion : public ParentT {
+ public:
+  using ParentT::ParentT;
+  void set_version(int32 version) {
+    version_ = version;
+  }
+  int32 version() const {
+    return version_;
+  }
+
+ private:
+  int32 version_;
+};
+
+template <class ParentT, class ContextT>
+class WithContext : public ParentT {
+ public:
+  using ParentT::ParentT;
+  void set_context(ContextT context) {
+    context_ = context;
+  }
+  ContextT context() const {
+    return context_;
+  }
+
+ private:
+  ContextT context_;
+};
+
+class LogEvent {
+ public:
+  LogEvent() = default;
+  LogEvent(const LogEvent &) = delete;
+  LogEvent &operator=(const LogEvent &) = delete;
+  virtual ~LogEvent() = default;
+  enum HandlerType : uint32 {
+    SecretChats = 1,
+    Users = 2,
+    Chats = 3,
+    Channels = 4,
+    SecretChatInfos = 5,
+    WebPages = 0x10,
+    SendMessage = 0x100,
+    DeleteMessage = 0x101,
+    DeleteMessagesFromServer = 0x102,
+    ReadHistoryOnServer = 0x103,
+    ForwardMessages = 0x104,
+    ReadMessageContentsOnServer = 0x105,
+    SendBotStartMessage = 0x106,
+    SendScreenshotTakenNotificationMessage = 0x107,
+    SendInlineQueryResultMessage = 0x108,
+    DeleteDialogHistoryFromServer = 0x109,
+    ReadAllDialogMentionsOnServer = 0x10a,
+    DeleteAllChannelMessagesFromUserOnServer = 0x10b,
+    ToggleDialogIsPinnedOnServer = 0x10c,
+    ReorderPinnedDialogsOnServer = 0x10d,
+    SaveDialogDraftMessageOnServer = 0x10e,
+    GetChannelDifference = 0x140,
+    ConfigPmcMagic = 0x1f18,
+    BinlogPmcMagic = 0x4327
+  };
+
+  using Id = uint64;
+
+  Id logevent_id() const {
+    return logevent_id_;
+  }
+  void set_logevent_id(Id logevent_id) {
+    logevent_id_ = logevent_id;
+  }
+
+  virtual StringBuilder &print(StringBuilder &sb) const {
+    return sb << "[Logevent " << tag("id", logevent_id()) << "]";
+  }
+
+ private:
+  Id logevent_id_;
+};
+inline StringBuilder &operator<<(StringBuilder &sb, const LogEvent &log_event) {
+  return log_event.print(sb);
+}
+
+namespace detail {
+
+template <class EventT>
+int32 magic(EventT &event) {
+  return static_cast<int32>(event.get_type());
+}
+
+template <class EventT, class StorerT>
+void store(const EventT &event, StorerT &storer) {
+  EventT::downcast_call(event.get_type(),
+                        [&](auto *ptr) { static_cast<const std::decay_t<decltype(*ptr)> &>(event).store(storer); });
+}
+
+template <class DestT, class T>
+Result<std::unique_ptr<DestT>> from_parser(T &&parser) {
+  auto version = parser.fetch_int();
+  parser.set_version(version);
+  parser.set_context(G());
+  auto magic = static_cast<typename DestT::Type>(parser.fetch_int());
+
+  std::unique_ptr<DestT> event;
+  DestT::downcast_call(magic, [&](auto *ptr) {
+    auto tmp = make_unique<std::decay_t<decltype(*ptr)>>();
+    tmp->parse(parser);
+    event = std::move(tmp);
+  });
+  parser.fetch_end();
+  TRY_STATUS(parser.get_status());
+  if (event) {
+    return std::move(event);
+  }
+  return Status::Error(PSLICE() << "Unknown SecretChatEvent type: " << format::as_hex(magic));
+}
+
+template <class DestT>
+Result<std::unique_ptr<DestT>> from_buffer_slice(BufferSlice slice) {
+  return from_parser<DestT>(WithVersion<WithContext<TlBufferParser, Global *>>{&slice});
+}
+
+template <class T>
+class StorerImpl : public Storer {
+ public:
+  explicit StorerImpl(const T &event) : event_(event) {
+  }
+
+  size_t size() const override {
+    WithContext<TlStorerCalcLength, Global *> storer;
+    storer.set_context(G());
+
+    storer.store_int(T::version());
+    td::store(magic(event_), storer);
+    td::store(event_, storer);
+    return storer.get_length();
+  }
+  size_t store(uint8 *ptr_x) const override {
+    char *ptr = reinterpret_cast<char *>(ptr_x);
+    WithContext<TlStorerUnsafe, Global *> storer(ptr);
+    storer.set_context(G());
+
+    storer.store_int(T::version());
+    td::store(magic(event_), storer);
+    td::store(event_, storer);
+    return storer.get_buf() - ptr;
+  }
+
+ private:
+  const T &event_;
+};
+}  // namespace detail
+
+template <class ChildT>
+class LogEventBase : public LogEvent {
+ public:
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    detail::store(static_cast<const ChildT &>(*this), storer);
+  }
+  static Result<std::unique_ptr<ChildT>> from_buffer_slice(BufferSlice slice) {
+    return detail::from_buffer_slice<ChildT>(std::move(slice));
+  }
+};
+
+template <class ChildT, class ParentT>
+class LogEventHelper : public ParentT {
+ public:
+  typename ParentT::Type get_type() const override {
+    return ChildT::type;
+  }
+
+  constexpr int32 magic() const {
+    return static_cast<int32>(get_type());
+  }
+};
+
+class LogEventParser : public WithVersion<WithContext<TlParser, Global *>> {
+ public:
+  explicit LogEventParser(Slice data) : WithVersion<WithContext<TlParser, Global *>>(data) {
+    set_version(fetch_int());
+    CHECK(version() < static_cast<int32>(Version::Next)) << "Wrong version " << version();
+    set_context(G());
+  }
+};
+
+class LogEventStorerCalcLength : public WithContext<TlStorerCalcLength, Global *> {
+ public:
+  LogEventStorerCalcLength() : WithContext<TlStorerCalcLength, Global *>() {
+    store_int(static_cast<int32>(Version::Next) - 1);
+    set_context(G());
+  }
+};
+
+class LogEventStorerUnsafe : public WithContext<TlStorerUnsafe, Global *> {
+ public:
+  explicit LogEventStorerUnsafe(char *buf) : WithContext<TlStorerUnsafe, Global *>(buf) {
+    store_int(static_cast<int32>(Version::Next) - 1);
+    set_context(G());
+  }
+};
+
+}  // namespace logevent
+
+using LogEvent = logevent::LogEvent;
+using LogEventParser = logevent::LogEventParser;
+using LogEventStorerCalcLength = logevent::LogEventStorerCalcLength;
+using LogEventStorerUnsafe = logevent::LogEventStorerUnsafe;
+
+template <class T>
+Status log_event_parse(T &data, Slice slice) TD_WARN_UNUSED_RESULT;
+
+template <class T>
+Status log_event_parse(T &data, Slice slice) {
+  LogEventParser parser(slice);
+  parse(data, parser);
+  parser.fetch_end();
+  return parser.get_status();
+}
+
+template <class T>
+class LogEventStorerImpl : public Storer {
+ public:
+  explicit LogEventStorerImpl(const T &event) : event_(event) {
+  }
+
+  size_t size() const override {
+    LogEventStorerCalcLength storer;
+    td::store(event_, storer);
+    return storer.get_length();
+  }
+  size_t store(uint8 *ptr_x) const override {
+    char *ptr = reinterpret_cast<char *>(ptr_x);
+    LogEventStorerUnsafe storer(ptr);
+    td::store(event_, storer);
+#ifdef TD_DEBUG
+    T check_result;
+    log_event_parse(check_result, Slice(ptr, storer.get_buf())).ensure();
+#endif
+    return storer.get_buf() - ptr;
+  }
+
+ private:
+  const T &event_;
+};
+
+template <class T>
+BufferSlice log_event_store(const T &data) {
+  LogEventStorerCalcLength storer_calc_length;
+  store(data, storer_calc_length);
+
+  BufferSlice value_buffer{storer_calc_length.get_length()};
+
+  LogEventStorerUnsafe storer_unsafe(value_buffer.as_slice().begin());
+  store(data, storer_unsafe);
+
+#ifdef TD_DEBUG
+  T check_result;
+  log_event_parse(check_result, value_buffer.as_slice()).ensure();
+#endif
+  return value_buffer;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/logevent/SecretChatEvent.h b/libs/tdlib/td/td/telegram/logevent/SecretChatEvent.h
new file mode 100644
index 0000000000..5b12f7b014
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/logevent/SecretChatEvent.h
@@ -0,0 +1,452 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/logevent/LogEvent.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/Storer.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tl_helpers.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/telegram_api.h"
+
+namespace td {
+namespace logevent {
+
+class SecretChatEvent : public LogEventBase<SecretChatEvent> {
+ public:
+  // append only enum
+  enum class Type : int32 {
+    InboundSecretMessage = 1,
+    OutboundSecretMessage = 2,
+    CloseSecretChat = 3,
+    CreateSecretChat = 4
+  };
+
+  virtual Type get_type() const = 0;
+
+  static constexpr LogEvent::HandlerType get_handler_type() {
+    return LogEvent::HandlerType::SecretChats;
+  }
+
+  static constexpr int32 version() {
+    return 2;
+  }
+
+  template <class F>
+  static void downcast_call(Type type, F &&f);
+};
+
+// Internal structure
+
+// inputEncryptedFileEmpty#1837c364 = InputEncryptedFile;
+// inputEncryptedFileUploaded#64bd0306 id:long parts:int md5_checksum:string key_fingerprint:int = InputEncryptedFile;
+// inputEncryptedFile#5a17b5e5 id:long access_hash:long = InputEncryptedFile;
+// inputEncryptedFileBigUploaded#2dc173c8 id:long parts:int key_fingerprint:int = InputEncryptedFile;
+struct EncryptedInputFile {
+  static constexpr int32 magic = 0x4328d38a;
+  enum Type : int32 { Empty = 0, Uploaded = 1, BigUploaded = 2, Location = 3 } type;
+  int64 id;
+  int64 access_hash;
+  int32 parts;
+  int32 key_fingerprint;
+  template <class T>
+  void store(T &storer) const {
+    using td::store;
+    store(magic, storer);
+    store(type, storer);
+    store(id, storer);
+    store(access_hash, storer);
+    store(parts, storer);
+    store(key_fingerprint, storer);
+  }
+
+  bool empty() const {
+    return type == Empty;
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using td::parse;
+    int32 got_magic;
+
+    parse(got_magic, parser);
+    parse(type, parser);
+    parse(id, parser);
+    parse(access_hash, parser);
+    parse(parts, parser);
+    parse(key_fingerprint, parser);
+
+    if (got_magic != magic) {
+      parser.set_error("EncryptedInputFile magic mismatch");
+      return;
+    }
+  }
+  static EncryptedInputFile from_input_encrypted_file(const tl_object_ptr<telegram_api::InputEncryptedFile> &from) {
+    if (!from) {
+      return EncryptedInputFile{Empty, 0, 0, 0, 0};
+    }
+    return from_input_encrypted_file(*from);
+  }
+  static EncryptedInputFile from_input_encrypted_file(const telegram_api::InputEncryptedFile &from) {
+    switch (from.get_id()) {
+      case telegram_api::inputEncryptedFileEmpty::ID:
+        return EncryptedInputFile{Empty, 0, 0, 0, 0};
+      case telegram_api::inputEncryptedFileUploaded::ID: {
+        auto &uploaded = static_cast<const telegram_api::inputEncryptedFileUploaded &>(from);
+        return EncryptedInputFile{Uploaded, uploaded.id_, 0, uploaded.parts_, uploaded.key_fingerprint_};
+      }
+      case telegram_api::inputEncryptedFileBigUploaded::ID: {
+        auto &uploaded = static_cast<const telegram_api::inputEncryptedFileBigUploaded &>(from);
+        return EncryptedInputFile{BigUploaded, uploaded.id_, 0, uploaded.parts_, uploaded.key_fingerprint_};
+      }
+      case telegram_api::inputEncryptedFile::ID: {
+        auto &uploaded = static_cast<const telegram_api::inputEncryptedFile &>(from);
+        return EncryptedInputFile{Location, uploaded.id_, uploaded.access_hash_, 0, 0};
+      }
+      default:
+        UNREACHABLE();
+    }
+  }
+  tl_object_ptr<telegram_api::InputEncryptedFile> as_input_encrypted_file() const {
+    switch (type) {
+      case Empty:
+        return make_tl_object<telegram_api::inputEncryptedFileEmpty>();
+      case Uploaded:
+        return make_tl_object<telegram_api::inputEncryptedFileUploaded>(id, parts, "", key_fingerprint);
+      case BigUploaded:
+        return make_tl_object<telegram_api::inputEncryptedFileBigUploaded>(id, parts, key_fingerprint);
+      case Location:
+        return make_tl_object<telegram_api::inputEncryptedFile>(id, access_hash);
+    }
+    UNREACHABLE();
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &sb, const EncryptedInputFile &file) {
+  return sb << to_string(file.as_input_encrypted_file());
+}
+
+// encryptedFile#4a70994c id:long access_hash:long size:int dc_id:int key_fingerprint:int = EncryptedFile;
+struct EncryptedFileLocation {
+  static constexpr int32 magic = 0x473d738a;
+  int64 id;
+  int64 access_hash;
+  int32 size;
+  int32 dc_id;
+  int32 key_fingerprint;
+
+  tl_object_ptr<telegram_api::encryptedFile> as_encrypted_file() {
+    return make_tl_object<telegram_api::encryptedFile>(id, access_hash, size, dc_id, key_fingerprint);
+  }
+  template <class T>
+  void store(T &storer) const {
+    using td::store;
+    store(magic, storer);
+    store(id, storer);
+    store(access_hash, storer);
+    store(size, storer);
+    store(dc_id, storer);
+    store(key_fingerprint, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using td::parse;
+    int32 got_magic;
+
+    parse(got_magic, parser);
+    parse(id, parser);
+    parse(access_hash, parser);
+    parse(size, parser);
+    parse(dc_id, parser);
+    parse(key_fingerprint, parser);
+
+    if (got_magic != magic) {
+      parser.set_error("EncryptedFileLocation magic mismatch");
+      return;
+    }
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &sb, const EncryptedFileLocation &file) {
+  return sb << "[" << tag("id", file.id) << tag("access_hash", file.access_hash) << tag("size", file.size)
+            << tag("dc_id", file.dc_id) << tag("key_fingerprint", file.key_fingerprint) << "]";
+}
+
+// LogEvents
+// TODO: Qts and SeqNoState could be just Logevents that are updated during regenerate
+class InboundSecretMessage : public LogEventHelper<InboundSecretMessage, SecretChatEvent> {
+ public:
+  static constexpr Type type = SecretChatEvent::Type::InboundSecretMessage;
+  int32 qts = 0;
+
+  int32 chat_id = 0;
+  int32 date = 0;
+
+  BufferSlice encrypted_message;  // empty when we store event to binlog
+  Promise<Unit> qts_ack;
+
+  bool is_checked = false;
+  // after decrypted and checked
+  tl_object_ptr<secret_api::decryptedMessageLayer> decrypted_message_layer;
+
+  uint64 auth_key_id = 0;
+  int32 message_id = 0;
+  int32 my_in_seq_no = -1;
+  int32 my_out_seq_no = -1;
+  int32 his_in_seq_no = -1;
+
+  EncryptedFileLocation file;
+
+  bool has_encrypted_file;
+  bool is_pending = false;
+
+  template <class T>
+  void store(T &storer) const {
+    using td::store;
+
+    BEGIN_STORE_FLAGS();
+    STORE_FLAG(has_encrypted_file);
+    STORE_FLAG(is_pending);
+    END_STORE_FLAGS();
+
+    store(qts, storer);
+    store(chat_id, storer);
+    store(date, storer);
+    // skip encrypted_message
+    // skip qts_ack
+
+    // TODO
+    decrypted_message_layer->store(storer);
+    storer.store_long(static_cast<int64>(auth_key_id));
+
+    store(message_id, storer);
+    store(my_in_seq_no, storer);
+    store(my_out_seq_no, storer);
+    store(his_in_seq_no, storer);
+    if (has_encrypted_file) {
+      store(file, storer);
+    }
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using td::parse;
+
+    BEGIN_PARSE_FLAGS();
+    PARSE_FLAG(has_encrypted_file);
+    PARSE_FLAG(is_pending);
+    END_PARSE_FLAGS();
+
+    parse(qts, parser);
+    parse(chat_id, parser);
+    parse(date, parser);
+    // skip encrypted_message
+    // skip qts_ack
+
+    // TODO
+    decrypted_message_layer = secret_api::decryptedMessageLayer::fetch(parser);
+    auth_key_id = static_cast<uint64>(parser.fetch_long());
+
+    parse(message_id, parser);
+    parse(my_in_seq_no, parser);
+    parse(my_out_seq_no, parser);
+    parse(his_in_seq_no, parser);
+    if (has_encrypted_file) {
+      parse(file, parser);
+    }
+
+    is_checked = true;
+  }
+
+  StringBuilder &print(StringBuilder &sb) const override {
+    return sb << "[Logevent InboundSecretMessage " << tag("id", logevent_id())
+              << tag("auth_key_id", format::as_hex(auth_key_id)) << tag("message_id", message_id)
+              << tag("my_in_seq_no", my_in_seq_no) << tag("my_out_seq_no", my_out_seq_no)
+              << tag("his_in_seq_no", his_in_seq_no) << tag("message", to_string(decrypted_message_layer))
+              << tag("is_pending", is_pending) << format::cond(has_encrypted_file, tag("file", file)) << "]";
+  }
+};
+
+class OutboundSecretMessage : public LogEventHelper<OutboundSecretMessage, SecretChatEvent> {
+ public:
+  static constexpr Type type = SecretChatEvent::Type::OutboundSecretMessage;
+
+  int32 chat_id = 0;
+  int64 random_id = 0;
+
+  BufferSlice encrypted_message;
+  EncryptedInputFile file;
+
+  int32 message_id = 0;
+  int32 my_in_seq_no = -1;
+  int32 my_out_seq_no = -1;
+  int32 his_in_seq_no = -1;
+
+  bool is_sent = false;
+  bool is_service = false;
+  bool is_rewritable = false;
+  bool is_external = false;
+
+  tl_object_ptr<secret_api::DecryptedMessageAction> action;
+  uint64 crc = 0;  // DEBUG;
+
+  // Flags:
+  // 2. can_fail = !file.empty() // send of other messages can't fail if chat is ok. It is usless to rewrite them with
+  // empty
+  // 1. is_service // use messages_sendEncryptedsService
+  // 3. can_rewrite_with_empty // false for almost all service messages
+
+  // TODO: combine this two functions into one macros hell. Or lambda hell.
+  template <class T>
+  void store(T &storer) const {
+    using td::store;
+
+    store(chat_id, storer);
+    store(random_id, storer);
+    store(encrypted_message, storer);
+    store(file, storer);
+    store(message_id, storer);
+    store(my_in_seq_no, storer);
+    store(my_out_seq_no, storer);
+    store(his_in_seq_no, storer);
+
+    bool has_action = static_cast<bool>(action);
+    BEGIN_STORE_FLAGS();
+    STORE_FLAG(is_sent);
+    STORE_FLAG(is_service);
+    STORE_FLAG(has_action);
+    STORE_FLAG(is_rewritable);
+    STORE_FLAG(is_external);
+    END_STORE_FLAGS();
+
+    if (has_action) {
+      CHECK(action);
+      // TODO
+      storer.store_int(action->get_id());
+      action->store(storer);
+    }
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using td::parse;
+
+    parse(chat_id, parser);
+    parse(random_id, parser);
+    parse(encrypted_message, parser);
+    parse(file, parser);
+    parse(message_id, parser);
+    parse(my_in_seq_no, parser);
+    parse(my_out_seq_no, parser);
+    parse(his_in_seq_no, parser);
+
+    bool has_action;
+    BEGIN_PARSE_FLAGS();
+    PARSE_FLAG(is_sent);
+    PARSE_FLAG(is_service);
+    PARSE_FLAG(has_action);
+    PARSE_FLAG(is_rewritable);
+    PARSE_FLAG(is_external);
+    END_PARSE_FLAGS();
+
+    if (has_action) {
+      // TODO:
+      action = secret_api::DecryptedMessageAction::fetch(parser);
+    }
+  }
+
+  StringBuilder &print(StringBuilder &sb) const override {
+    return sb << "[Logevent OutboundSecretMessage " << tag("id", logevent_id()) << tag("is_sent", is_sent)
+              << tag("is_service", is_service) << tag("is_rewritable", is_rewritable) << tag("is_external", is_external)
+              << tag("message_id", message_id) << tag("random_id", random_id) << tag("my_in_seq_no", my_in_seq_no)
+              << tag("my_out_seq_no", my_out_seq_no) << tag("his_in_seq_no", his_in_seq_no) << tag("file", file)
+              << tag("action", to_string(action)) << "]";
+  }
+};
+
+class CloseSecretChat : public LogEventHelper<CloseSecretChat, SecretChatEvent> {
+ public:
+  static constexpr Type type = SecretChatEvent::Type::CloseSecretChat;
+  int32 chat_id = 0;
+
+  template <class T>
+  void store(T &storer) const {
+    using td::store;
+    store(chat_id, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using td::parse;
+    parse(chat_id, parser);
+  }
+
+  StringBuilder &print(StringBuilder &sb) const override {
+    return sb << "[Logevent CloseSecretChat " << tag("id", logevent_id()) << tag("chat_id", chat_id) << "]";
+  }
+};
+
+class CreateSecretChat : public LogEventHelper<CreateSecretChat, SecretChatEvent> {
+ public:
+  static constexpr Type type = SecretChatEvent::Type::CreateSecretChat;
+  int32 random_id = 0;
+  int32 user_id = 0;
+  int64 user_access_hash = 0;
+
+  template <class T>
+  void store(T &storer) const {
+    using td::store;
+    store(random_id, storer);
+    store(user_id, storer);
+    store(user_access_hash, storer);
+  }
+
+  template <class T>
+  void parse(T &parser) {
+    using td::parse;
+    parse(random_id, parser);
+    parse(user_id, parser);
+    parse(user_access_hash, parser);
+  }
+
+  StringBuilder &print(StringBuilder &sb) const override {
+    return sb << "[Logevent CreateSecretChat " << tag("id", logevent_id()) << tag("chat_id", random_id) << "]";
+  }
+};
+
+template <class F>
+void SecretChatEvent::downcast_call(Type type, F &&f) {
+  switch (type) {
+    case Type::InboundSecretMessage:
+      f(static_cast<InboundSecretMessage *>(nullptr));
+      break;
+    case Type::OutboundSecretMessage:
+      f(static_cast<OutboundSecretMessage *>(nullptr));
+      break;
+    case Type::CloseSecretChat:
+      f(static_cast<CloseSecretChat *>(nullptr));
+      break;
+    case Type::CreateSecretChat:
+      f(static_cast<CreateSecretChat *>(nullptr));
+      break;
+    default:
+      break;
+  }
+}
+}  // namespace logevent
+
+inline auto create_storer(logevent::SecretChatEvent &event) {
+  return logevent::detail::StorerImpl<logevent::SecretChatEvent>(event);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/misc.cpp b/libs/tdlib/td/td/telegram/misc.cpp
new file mode 100644
index 0000000000..282906279d
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/misc.cpp
@@ -0,0 +1,273 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/misc.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Slice.h"
+#include "td/utils/utf8.h"
+
+#include <algorithm>
+#include <cstring>
+#include <limits>
+
+namespace td {
+
+string clean_name(string str, size_t max_length) {
+  str = strip_empty_characters(str, max_length);
+  size_t new_len = 0;
+  bool is_previous_space = false;
+  for (size_t i = 0; i < str.size(); i++) {
+    if (str[i] == ' ' || str[i] == '\n') {
+      if (!is_previous_space) {
+        str[new_len++] = ' ';
+        is_previous_space = true;
+      }
+      continue;
+    }
+    if (static_cast<unsigned char>(str[i]) == 0xC2 && static_cast<unsigned char>(str[i + 1]) == 0xA0) {  // &nbsp;
+      if (!is_previous_space) {
+        str[new_len++] = ' ';
+        is_previous_space = true;
+      }
+      i++;
+      continue;
+    }
+
+    str[new_len++] = str[i];
+    is_previous_space = false;
+  }
+  str.resize(new_len);
+  return trim(str);
+}
+
+string clean_username(string str) {
+  str.resize(std::remove(str.begin(), str.end(), '.') - str.begin());
+  return trim(to_lower(str));
+}
+
+bool clean_input_string(string &str) {
+  constexpr size_t LENGTH_LIMIT = 35000;  // server side limit
+  if (!check_utf8(str)) {
+    return false;
+  }
+
+  size_t str_size = str.size();
+  size_t new_size = 0;
+  for (size_t pos = 0; pos < str_size; pos++) {
+    unsigned char c = static_cast<unsigned char>(str[pos]);
+    switch (c) {
+      // remove control characters
+      case 0:
+      case 1:
+      case 2:
+      case 3:
+      case 4:
+      case 5:
+      case 6:
+      case 7:
+      case 8:
+      case 9:
+      // allow '\n'
+      case 11:
+      case 12:
+      // ignore '\r'
+      case 14:
+      case 15:
+      case 16:
+      case 17:
+      case 18:
+      case 19:
+      case 20:
+      case 21:
+      case 22:
+      case 23:
+      case 24:
+      case 25:
+      case 26:
+      case 27:
+      case 28:
+      case 29:
+      case 30:
+      case 31:
+      case 32:
+        str[new_size++] = ' ';
+        break;
+      case '\r':
+        // skip
+        break;
+      default:
+        // remove \xe2\x80[\xa8-\xae]
+        if (c == 0xe2 && pos + 2 < str_size) {
+          unsigned char next = static_cast<unsigned char>(str[pos + 1]);
+          if (next == 0x80) {
+            next = static_cast<unsigned char>(str[pos + 2]);
+            if (0xa8 <= next && next <= 0xae) {
+              pos += 2;
+              break;
+            }
+          }
+        }
+        // remove vertical lines \xcc[\xb3\xbf\x8a]
+        if (c == 0xcc && pos + 1 < str_size) {
+          unsigned char next = static_cast<unsigned char>(str[pos + 1]);
+          if (next == 0xb3 || next == 0xbf || next == 0x8a) {
+            pos++;
+            break;
+          }
+        }
+
+        str[new_size++] = str[pos];
+        break;
+    }
+    if (new_size >= LENGTH_LIMIT - 3 && is_utf8_character_first_code_unit(str[new_size - 1])) {
+      new_size--;
+      break;
+    }
+  }
+
+  str.resize(new_size);
+  return true;
+}
+
+string strip_empty_characters(string str, size_t max_length) {
+  static const char *space_characters[] = {u8"\u1680", u8"\u180E", u8"\u2000", u8"\u2001", u8"\u2002",
+                                           u8"\u2003", u8"\u2004", u8"\u2005", u8"\u2006", u8"\u2007",
+                                           u8"\u2008", u8"\u2009", u8"\u200A", u8"\u200B", u8"\u202F",
+                                           u8"\u205F", u8"\u3000", u8"\uFEFF", u8"\uFFFC"};
+  static bool can_be_first[std::numeric_limits<unsigned char>::max() + 1];
+  static bool can_be_first_inited = [&] {
+    for (auto space_ch : space_characters) {
+      CHECK(std::strlen(space_ch) == 3);
+      can_be_first[static_cast<unsigned char>(space_ch[0])] = true;
+    }
+    return true;
+  }();
+  CHECK(can_be_first_inited);
+
+  // replace all occurences of space characters with a space
+  size_t i = 0;
+  while (i < str.size() && !can_be_first[static_cast<unsigned char>(str[i])]) {
+    i++;
+  }
+  size_t new_len = i;
+  while (i < str.size()) {
+    if (can_be_first[static_cast<unsigned char>(str[i])] && i + 3 <= str.size()) {
+      bool found = false;
+      for (auto space_ch : space_characters) {
+        if (space_ch[0] == str[i] && space_ch[1] == str[i + 1] && space_ch[2] == str[i + 2]) {
+          found = true;
+          break;
+        }
+      }
+      if (found) {
+        str[new_len++] = ' ';
+        i += 3;
+        continue;
+      }
+    }
+    str[new_len++] = str[i++];
+  }
+  Slice trimmed = trim(utf8_truncate(trim(Slice(str.c_str(), new_len)), max_length));
+
+  // check if there is some non-empty character, empty characters:
+  // "\xE2\x80\x8C", ZERO WIDTH NON-JOINER
+  // "\xE2\x80\x8D", ZERO WIDTH JOINER
+  // "\xE2\x80\xAE", RIGHT-TO-LEFT OVERRIDE
+  // "\xC2\xA0", NO-BREAK SPACE
+  for (i = 0;;) {
+    if (i == trimmed.size()) {
+      // if all characters are empty, return an empty string
+      return string();
+    }
+
+    if (static_cast<unsigned char>(trimmed[i]) == 0xE2 && static_cast<unsigned char>(trimmed[i + 1]) == 0x80 &&
+        (static_cast<unsigned char>(trimmed[i + 2]) == 0x8C || static_cast<unsigned char>(trimmed[i + 2]) == 0x8D ||
+         static_cast<unsigned char>(trimmed[i + 2]) == 0xAE)) {
+      i += 3;
+      continue;
+    }
+    if (static_cast<unsigned char>(trimmed[i]) == 0xC2 && static_cast<unsigned char>(trimmed[i + 1]) == 0xA0) {
+      i += 2;
+      continue;
+    }
+    break;
+  }
+  return trimmed.str();
+}
+
+bool is_empty_string(const string &str) {
+  return strip_empty_characters(str, str.size()).empty();
+}
+
+int32 get_vector_hash(const vector<uint32> &numbers) {
+  uint32 acc = 0;
+  for (auto number : numbers) {
+    acc = acc * 20261 + number;
+  }
+  return static_cast<int32>(acc & 0x7FFFFFFF);
+}
+
+string get_emoji_fingerprint(uint64 num) {
+  static const vector<Slice> emojis{
+      u8"\U0001f609", u8"\U0001f60d", u8"\U0001f61b", u8"\U0001f62d", u8"\U0001f631", u8"\U0001f621", u8"\U0001f60e",
+      u8"\U0001f634", u8"\U0001f635", u8"\U0001f608", u8"\U0001f62c", u8"\U0001f607", u8"\U0001f60f", u8"\U0001f46e",
+      u8"\U0001f477", u8"\U0001f482", u8"\U0001f476", u8"\U0001f468", u8"\U0001f469", u8"\U0001f474", u8"\U0001f475",
+      u8"\U0001f63b", u8"\U0001f63d", u8"\U0001f640", u8"\U0001f47a", u8"\U0001f648", u8"\U0001f649", u8"\U0001f64a",
+      u8"\U0001f480", u8"\U0001f47d", u8"\U0001f4a9", u8"\U0001f525", u8"\U0001f4a5", u8"\U0001f4a4", u8"\U0001f442",
+      u8"\U0001f440", u8"\U0001f443", u8"\U0001f445", u8"\U0001f444", u8"\U0001f44d", u8"\U0001f44e", u8"\U0001f44c",
+      u8"\U0001f44a", u8"\u270c", u8"\u270b", u8"\U0001f450", u8"\U0001f446", u8"\U0001f447", u8"\U0001f449",
+      u8"\U0001f448", u8"\U0001f64f", u8"\U0001f44f", u8"\U0001f4aa", u8"\U0001f6b6", u8"\U0001f3c3", u8"\U0001f483",
+      u8"\U0001f46b", u8"\U0001f46a", u8"\U0001f46c", u8"\U0001f46d", u8"\U0001f485", u8"\U0001f3a9", u8"\U0001f451",
+      u8"\U0001f452", u8"\U0001f45f", u8"\U0001f45e", u8"\U0001f460", u8"\U0001f455", u8"\U0001f457", u8"\U0001f456",
+      u8"\U0001f459", u8"\U0001f45c", u8"\U0001f453", u8"\U0001f380", u8"\U0001f484", u8"\U0001f49b", u8"\U0001f499",
+      u8"\U0001f49c", u8"\U0001f49a", u8"\U0001f48d", u8"\U0001f48e", u8"\U0001f436", u8"\U0001f43a", u8"\U0001f431",
+      u8"\U0001f42d", u8"\U0001f439", u8"\U0001f430", u8"\U0001f438", u8"\U0001f42f", u8"\U0001f428", u8"\U0001f43b",
+      u8"\U0001f437", u8"\U0001f42e", u8"\U0001f417", u8"\U0001f434", u8"\U0001f411", u8"\U0001f418", u8"\U0001f43c",
+      u8"\U0001f427", u8"\U0001f425", u8"\U0001f414", u8"\U0001f40d", u8"\U0001f422", u8"\U0001f41b", u8"\U0001f41d",
+      u8"\U0001f41c", u8"\U0001f41e", u8"\U0001f40c", u8"\U0001f419", u8"\U0001f41a", u8"\U0001f41f", u8"\U0001f42c",
+      u8"\U0001f40b", u8"\U0001f410", u8"\U0001f40a", u8"\U0001f42b", u8"\U0001f340", u8"\U0001f339", u8"\U0001f33b",
+      u8"\U0001f341", u8"\U0001f33e", u8"\U0001f344", u8"\U0001f335", u8"\U0001f334", u8"\U0001f333", u8"\U0001f31e",
+      u8"\U0001f31a", u8"\U0001f319", u8"\U0001f30e", u8"\U0001f30b", u8"\u26a1", u8"\u2614", u8"\u2744", u8"\u26c4",
+      u8"\U0001f300", u8"\U0001f308", u8"\U0001f30a", u8"\U0001f393", u8"\U0001f386", u8"\U0001f383", u8"\U0001f47b",
+      u8"\U0001f385", u8"\U0001f384", u8"\U0001f381", u8"\U0001f388", u8"\U0001f52e", u8"\U0001f3a5", u8"\U0001f4f7",
+      u8"\U0001f4bf", u8"\U0001f4bb", u8"\u260e", u8"\U0001f4e1", u8"\U0001f4fa", u8"\U0001f4fb", u8"\U0001f509",
+      u8"\U0001f514", u8"\u23f3", u8"\u23f0", u8"\u231a", u8"\U0001f512", u8"\U0001f511", u8"\U0001f50e",
+      u8"\U0001f4a1", u8"\U0001f526", u8"\U0001f50c", u8"\U0001f50b", u8"\U0001f6bf", u8"\U0001f6bd", u8"\U0001f527",
+      u8"\U0001f528", u8"\U0001f6aa", u8"\U0001f6ac", u8"\U0001f4a3", u8"\U0001f52b", u8"\U0001f52a", u8"\U0001f48a",
+      u8"\U0001f489", u8"\U0001f4b0", u8"\U0001f4b5", u8"\U0001f4b3", u8"\u2709", u8"\U0001f4eb", u8"\U0001f4e6",
+      u8"\U0001f4c5", u8"\U0001f4c1", u8"\u2702", u8"\U0001f4cc", u8"\U0001f4ce", u8"\u2712", u8"\u270f",
+      u8"\U0001f4d0", u8"\U0001f4da", u8"\U0001f52c", u8"\U0001f52d", u8"\U0001f3a8", u8"\U0001f3ac", u8"\U0001f3a4",
+      u8"\U0001f3a7", u8"\U0001f3b5", u8"\U0001f3b9", u8"\U0001f3bb", u8"\U0001f3ba", u8"\U0001f3b8", u8"\U0001f47e",
+      u8"\U0001f3ae", u8"\U0001f0cf", u8"\U0001f3b2", u8"\U0001f3af", u8"\U0001f3c8", u8"\U0001f3c0", u8"\u26bd",
+      u8"\u26be", u8"\U0001f3be", u8"\U0001f3b1", u8"\U0001f3c9", u8"\U0001f3b3", u8"\U0001f3c1", u8"\U0001f3c7",
+      u8"\U0001f3c6", u8"\U0001f3ca", u8"\U0001f3c4", u8"\u2615", u8"\U0001f37c", u8"\U0001f37a", u8"\U0001f377",
+      u8"\U0001f374", u8"\U0001f355", u8"\U0001f354", u8"\U0001f35f", u8"\U0001f357", u8"\U0001f371", u8"\U0001f35a",
+      u8"\U0001f35c", u8"\U0001f361", u8"\U0001f373", u8"\U0001f35e", u8"\U0001f369", u8"\U0001f366", u8"\U0001f382",
+      u8"\U0001f370", u8"\U0001f36a", u8"\U0001f36b", u8"\U0001f36d", u8"\U0001f36f", u8"\U0001f34e", u8"\U0001f34f",
+      u8"\U0001f34a", u8"\U0001f34b", u8"\U0001f352", u8"\U0001f347", u8"\U0001f349", u8"\U0001f353", u8"\U0001f351",
+      u8"\U0001f34c", u8"\U0001f350", u8"\U0001f34d", u8"\U0001f346", u8"\U0001f345", u8"\U0001f33d", u8"\U0001f3e1",
+      u8"\U0001f3e5", u8"\U0001f3e6", u8"\u26ea", u8"\U0001f3f0", u8"\u26fa", u8"\U0001f3ed", u8"\U0001f5fb",
+      u8"\U0001f5fd", u8"\U0001f3a0", u8"\U0001f3a1", u8"\u26f2", u8"\U0001f3a2", u8"\U0001f6a2", u8"\U0001f6a4",
+      u8"\u2693", u8"\U0001f680", u8"\u2708", u8"\U0001f681", u8"\U0001f682", u8"\U0001f68b", u8"\U0001f68e",
+      u8"\U0001f68c", u8"\U0001f699", u8"\U0001f697", u8"\U0001f695", u8"\U0001f69b", u8"\U0001f6a8", u8"\U0001f694",
+      u8"\U0001f692", u8"\U0001f691", u8"\U0001f6b2", u8"\U0001f6a0", u8"\U0001f69c", u8"\U0001f6a6", u8"\u26a0",
+      u8"\U0001f6a7", u8"\u26fd", u8"\U0001f3b0", u8"\U0001f5ff", u8"\U0001f3aa", u8"\U0001f3ad",
+      u8"\U0001f1ef\U0001f1f5", u8"\U0001f1f0\U0001f1f7", u8"\U0001f1e9\U0001f1ea", u8"\U0001f1e8\U0001f1f3",
+      u8"\U0001f1fa\U0001f1f8", u8"\U0001f1eb\U0001f1f7", u8"\U0001f1ea\U0001f1f8", u8"\U0001f1ee\U0001f1f9",
+      u8"\U0001f1f7\U0001f1fa", u8"\U0001f1ec\U0001f1e7", u8"\u0031\u20e3", u8"\u0032\u20e3", u8"\u0033\u20e3",
+      u8"\u0034\u20e3", u8"\u0035\u20e3", u8"\u0036\u20e3", u8"\u0037\u20e3", u8"\u0038\u20e3", u8"\u0039\u20e3",
+      u8"\u0030\u20e3", u8"\U0001f51f", u8"\u2757", u8"\u2753", u8"\u2665", u8"\u2666", u8"\U0001f4af", u8"\U0001f517",
+      u8"\U0001f531", u8"\U0001f534", u8"\U0001f535", u8"\U0001f536",
+      // comment for clang-format
+      u8"\U0001f537"};
+
+  return emojis[(num & 0x7FFFFFFFFFFFFFFF) % emojis.size()].str();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/misc.h b/libs/tdlib/td/td/telegram/misc.h
new file mode 100644
index 0000000000..8efbb23c2f
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/misc.h
@@ -0,0 +1,34 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+namespace td {
+
+// cleans user name/dialog title
+string clean_name(string str, size_t max_length) TD_WARN_UNUSED_RESULT;
+
+// prepares username/stickername for search
+string clean_username(string str) TD_WARN_UNUSED_RESULT;
+
+// removes control characters from the string, will fail if input string is not in UTF-8
+bool clean_input_string(string &str) TD_WARN_UNUSED_RESULT;
+
+// strips empty characters and ensures that string length is no more than max_length
+string strip_empty_characters(string str, size_t max_length) TD_WARN_UNUSED_RESULT;
+
+// checks if string is empty after strip_empty_characters
+bool is_empty_string(const string &str) TD_WARN_UNUSED_RESULT;
+
+// calculates hash of list of uint32
+int32 get_vector_hash(const vector<uint32> &numbers) TD_WARN_UNUSED_RESULT;
+
+// returns emoji corresponding to the specified number
+string get_emoji_fingerprint(uint64 num);
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/AuthDataShared.cpp b/libs/tdlib/td/td/telegram/net/AuthDataShared.cpp
new file mode 100644
index 0000000000..318d472067
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/AuthDataShared.cpp
@@ -0,0 +1,119 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/AuthDataShared.h"
+
+#include "td/telegram/Global.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/RwMutex.h"
+#include "td/utils/tl_helpers.h"
+
+#include <algorithm>
+
+namespace td {
+
+class AuthDataSharedImpl : public AuthDataShared {
+ public:
+  AuthDataSharedImpl(DcId dc_id, std::shared_ptr<PublicRsaKeyShared> public_rsa_key, std::shared_ptr<Guard> guard)
+      : dc_id_(dc_id), public_rsa_key_(std::move(public_rsa_key)), guard_(std::move(guard)) {
+    log_auth_key(get_auth_key());
+  }
+
+  DcId dc_id() const override {
+    return dc_id_;
+  }
+
+  const std::shared_ptr<PublicRsaKeyShared> &public_rsa_key() override {
+    return public_rsa_key_;
+  }
+
+  mtproto::AuthKey get_auth_key() override {
+    string dc_key = G()->td_db()->get_binlog_pmc()->get(auth_key_key());
+
+    mtproto::AuthKey res;
+    if (!dc_key.empty()) {
+      unserialize(res, dc_key).ensure();
+    }
+    return res;
+  }
+  using AuthDataShared::get_auth_state;
+  std::pair<AuthState, bool> get_auth_state() override {
+    // TODO (perf):
+    auto auth_key = get_auth_key();
+    AuthState state = get_auth_state(auth_key);
+    return std::make_pair(state, auth_key.was_auth_flag());
+  }
+
+  void set_auth_key(const mtproto::AuthKey &auth_key) override {
+    G()->td_db()->get_binlog_pmc()->set(auth_key_key(), serialize(auth_key));
+    log_auth_key(auth_key);
+
+    notify();
+  }
+
+  // TODO: extract it from G()
+  void update_server_time_difference(double diff) override {
+    G()->update_server_time_difference(diff);
+  }
+
+  double get_server_time_difference() override {
+    return G()->get_server_time_difference();
+  }
+
+  void add_auth_key_listener(unique_ptr<Listener> listener) override {
+    if (listener->notify()) {
+      auto lock = rw_mutex_.lock_write();
+      auth_key_listeners_.push_back(std::move(listener));
+    }
+  }
+
+  void set_future_salts(const std::vector<mtproto::ServerSalt> &future_salts) override {
+    G()->td_db()->get_binlog_pmc()->set(future_salts_key(), serialize(future_salts));
+  }
+
+  std::vector<mtproto::ServerSalt> get_future_salts() override {
+    string future_salts = G()->td_db()->get_binlog_pmc()->get(future_salts_key());
+    std::vector<mtproto::ServerSalt> res;
+    if (!future_salts.empty()) {
+      unserialize(res, future_salts).ensure();
+    }
+    return res;
+  }
+
+ private:
+  DcId dc_id_;
+  std::vector<unique_ptr<Listener>> auth_key_listeners_;
+  std::shared_ptr<PublicRsaKeyShared> public_rsa_key_;
+  std::shared_ptr<Guard> guard_;
+  RwMutex rw_mutex_;
+
+  string auth_key_key() {
+    return PSTRING() << "auth" << dc_id_.get_raw_id();
+  }
+  string future_salts_key() {
+    return PSTRING() << "salt" << dc_id_.get_raw_id();
+  }
+
+  void notify() {
+    auto lock = rw_mutex_.lock_read();
+
+    auto it = std::remove_if(auth_key_listeners_.begin(), auth_key_listeners_.end(),
+                             [&](auto &listener) { return !listener->notify(); });
+    auth_key_listeners_.erase(it, auth_key_listeners_.end());
+  }
+
+  void log_auth_key(const mtproto::AuthKey &auth_key) {
+    LOG(WARNING) << dc_id_ << " " << tag("auth_key_id", auth_key.id()) << tag("state", get_auth_state(auth_key));
+  }
+};
+
+std::shared_ptr<AuthDataShared> AuthDataShared::create(DcId dc_id, std::shared_ptr<PublicRsaKeyShared> public_rsa_key,
+                                                       std::shared_ptr<Guard> guard) {
+  return std::make_shared<AuthDataSharedImpl>(dc_id, std::move(public_rsa_key), std::move(guard));
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/AuthDataShared.h b/libs/tdlib/td/td/telegram/net/AuthDataShared.h
new file mode 100644
index 0000000000..027aa80eda
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/AuthDataShared.h
@@ -0,0 +1,78 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/mtproto/AuthData.h"
+#include "td/mtproto/AuthKey.h"
+
+#include "td/telegram/net/DcId.h"
+#include "td/telegram/net/PublicRsaKeyShared.h"
+
+#include "td/utils/common.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/StringBuilder.h"
+
+#include <memory>
+#include <utility>
+
+namespace td {
+enum class AuthState : int32 { Empty, KeyNoAuth, OK };
+
+inline StringBuilder &operator<<(StringBuilder &sb, AuthState state) {
+  switch (state) {
+    case AuthState::Empty:
+      return sb << "Empty";
+    case AuthState::KeyNoAuth:
+      return sb << "KeyNoAuth";
+    case AuthState::OK:
+      return sb << "OK";
+    default:
+      return sb << "Unknown AuthState";
+  }
+}
+
+class AuthDataShared {
+ public:
+  virtual ~AuthDataShared() = default;
+  class Listener {
+   public:
+    Listener() = default;
+    Listener(const Listener &) = delete;
+    Listener &operator=(const Listener &) = delete;
+    virtual ~Listener() = default;
+    virtual bool notify() = 0;
+  };
+
+  virtual DcId dc_id() const = 0;
+  virtual const std::shared_ptr<PublicRsaKeyShared> &public_rsa_key() = 0;
+  virtual mtproto::AuthKey get_auth_key() = 0;
+  virtual std::pair<AuthState, bool> get_auth_state() = 0;
+  virtual void set_auth_key(const mtproto::AuthKey &auth_key) = 0;
+  virtual void update_server_time_difference(double diff) = 0;
+  virtual double get_server_time_difference() = 0;
+  virtual void add_auth_key_listener(unique_ptr<Listener> listener) = 0;
+
+  virtual void set_future_salts(const std::vector<mtproto::ServerSalt> &future_salts) = 0;
+  virtual std::vector<mtproto::ServerSalt> get_future_salts() = 0;
+
+  static AuthState get_auth_state(const mtproto::AuthKey &auth_key) {
+    AuthState state;
+    if (auth_key.empty()) {
+      state = AuthState::Empty;
+    } else if (auth_key.auth_flag()) {
+      state = AuthState::OK;
+    } else {
+      state = AuthState::KeyNoAuth;
+    }
+    return state;
+  }
+
+  static std::shared_ptr<AuthDataShared> create(DcId dc_id, std::shared_ptr<PublicRsaKeyShared> public_rsa_key,
+                                                std::shared_ptr<Guard> guard);
+};
+
+};  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/ConnectionCreator.cpp b/libs/tdlib/td/td/telegram/net/ConnectionCreator.cpp
new file mode 100644
index 0000000000..3805835ef3
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/ConnectionCreator.cpp
@@ -0,0 +1,712 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/ConnectionCreator.h"
+
+#include "td/telegram/ConfigManager.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/logevent/LogEvent.h"
+#include "td/telegram/StateManager.h"
+
+#include "td/mtproto/IStreamTransport.h"
+#include "td/mtproto/PingConnection.h"
+#include "td/mtproto/RawConnection.h"
+
+#include "td/net/GetHostByNameActor.h"
+#include "td/net/Socks5.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/IPAddress.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Time.h"
+#include "td/utils/tl_helpers.h"
+
+#include <algorithm>
+
+namespace td {
+
+namespace detail {
+
+class StatsCallback final : public mtproto::RawConnection::StatsCallback {
+ public:
+  StatsCallback(std::shared_ptr<NetStatsCallback> net_stats_callback, ActorId<ConnectionCreator> connection_creator,
+                size_t hash, DcOptionsSet::Stat *option_stat)
+      : net_stats_callback_(std::move(net_stats_callback))
+      , connection_creator_(std::move(connection_creator))
+      , hash_(hash)
+      , option_stat_(option_stat) {
+  }
+
+  void on_read(uint64 bytes) final {
+    net_stats_callback_->on_read(bytes);
+  }
+  void on_write(uint64 bytes) final {
+    net_stats_callback_->on_write(bytes);
+  }
+
+  void on_pong() final {
+    send_lambda(connection_creator_, [stat = option_stat_] { stat->on_ok(); });
+  }
+  void on_error() final {
+    send_lambda(connection_creator_, [stat = option_stat_] { stat->on_error(); });
+  }
+
+  void on_mtproto_error() final {
+    send_closure(connection_creator_, &ConnectionCreator::on_mtproto_error, hash_);
+  }
+
+ private:
+  std::shared_ptr<NetStatsCallback> net_stats_callback_;
+  ActorId<ConnectionCreator> connection_creator_;
+  size_t hash_;
+  DcOptionsSet::Stat *option_stat_;
+};
+
+class PingActor : public Actor {
+ public:
+  PingActor(std::unique_ptr<mtproto::RawConnection> raw_connection,
+            Promise<std::unique_ptr<mtproto::RawConnection>> promise, ActorShared<> parent)
+      : promise_(std::move(promise)), parent_(std::move(parent)) {
+    ping_connection_ = std::make_unique<mtproto::PingConnection>(std::move(raw_connection));
+  }
+
+ private:
+  std::unique_ptr<mtproto::PingConnection> ping_connection_;
+  Promise<std::unique_ptr<mtproto::RawConnection>> promise_;
+  ActorShared<> parent_;
+  double start_at_;
+
+  void start_up() override {
+    ping_connection_->get_pollable().set_observer(this);
+    subscribe(ping_connection_->get_pollable());
+    start_at_ = Time::now();
+    set_timeout_in(10);
+    yield();
+  }
+  void tear_down() override {
+    finish(Status::OK());
+  }
+
+  void loop() override {
+    auto status = ping_connection_->flush();
+    if (status.is_error()) {
+      finish(std::move(status));
+      return stop();
+    }
+    if (ping_connection_->was_pong()) {
+      finish(Status::OK());
+      return stop();
+    }
+  }
+
+  void timeout_expired() override {
+    finish(Status::Error("Pong timeout expired"));
+    stop();
+  }
+
+  void finish(Status status) {
+    auto raw_connection = ping_connection_->move_as_raw_connection();
+    if (!raw_connection) {
+      CHECK(!promise_);
+      return;
+    }
+    unsubscribe(raw_connection->get_pollable());
+    raw_connection->get_pollable().set_observer(nullptr);
+    if (promise_) {
+      if (status.is_error()) {
+        if (raw_connection->stats_callback()) {
+          raw_connection->stats_callback()->on_error();
+        }
+        raw_connection->close();
+        promise_.set_error(std::move(status));
+      } else {
+        raw_connection->rtt_ = Time::now() - start_at_;
+        if (raw_connection->stats_callback()) {
+          raw_connection->stats_callback()->on_pong();
+        }
+        promise_.set_value(std::move(raw_connection));
+      }
+    } else {
+      if (raw_connection->stats_callback()) {
+        raw_connection->stats_callback()->on_error();
+      }
+      raw_connection->close();
+    }
+  }
+};
+
+}  // namespace detail
+
+template <class T>
+void Proxy::parse(T &parser) {
+  using td::parse;
+  parse(type_, parser);
+  if (type_ == Proxy::Type::Socks5) {
+    parse(server_, parser);
+    parse(port_, parser);
+    parse(user_, parser);
+    parse(password_, parser);
+  } else {
+    CHECK(type_ == Proxy::Type::None);
+  }
+}
+
+template <class T>
+void Proxy::store(T &storer) const {
+  using td::store;
+  store(type_, storer);
+  if (type_ == Proxy::Type::Socks5) {
+    store(server_, storer);
+    store(port_, storer);
+    store(user_, storer);
+    store(password_, storer);
+  } else {
+    CHECK(type_ == Proxy::Type::None);
+  }
+}
+
+ConnectionCreator::ClientInfo::ClientInfo() {
+  flood_control.add_limit(1, 1);
+  flood_control.add_limit(4, 2);
+  flood_control.add_limit(8, 3);
+
+  flood_control_online.add_limit(1, 4);
+  flood_control_online.add_limit(5, 5);
+
+  mtproto_error_flood_control.add_limit(1, 1);
+  mtproto_error_flood_control.add_limit(4, 2);
+  mtproto_error_flood_control.add_limit(8, 3);
+}
+
+ConnectionCreator::ConnectionCreator(ActorShared<> parent) : parent_(std::move(parent)) {
+}
+
+ConnectionCreator::ConnectionCreator(ConnectionCreator &&other) = default;
+
+ConnectionCreator &ConnectionCreator::operator=(ConnectionCreator &&other) = default;
+
+ConnectionCreator::~ConnectionCreator() = default;
+
+void ConnectionCreator::set_net_stats_callback(std::shared_ptr<NetStatsCallback> common_callback,
+                                               std::shared_ptr<NetStatsCallback> media_callback) {
+  common_net_stats_callback_ = std::move(common_callback);
+  media_net_stats_callback_ = std::move(media_callback);
+}
+
+void ConnectionCreator::set_proxy(Proxy proxy) {
+  set_proxy_impl(std::move(proxy), false);
+  loop();
+}
+
+void ConnectionCreator::set_proxy_impl(Proxy proxy, bool from_db) {
+  if (proxy_ == proxy) {
+    return;
+  }
+
+  proxy_ = std::move(proxy);
+  send_closure(G()->state_manager(), &StateManager::on_proxy, proxy_.type() != Proxy::Type::None);
+
+  if (!from_db) {
+    G()->td_db()->get_binlog_pmc()->set("proxy", log_event_store(proxy_).as_slice().str());
+    for (auto &child : children_) {
+      child.second.reset();
+    }
+  }
+
+  resolve_proxy_query_token_ = 0;
+  resolve_proxy_timestamp_ = Timestamp();
+  proxy_ip_address_ = IPAddress();
+}
+
+void ConnectionCreator::get_proxy(Promise<Proxy> promise) {
+  promise.set_value(Proxy(proxy_));
+}
+
+void ConnectionCreator::on_network(bool network_flag, uint32 network_generation) {
+  network_flag_ = network_flag;
+  auto old_generation = network_generation_;
+  network_generation_ = network_generation;
+  if (network_flag_) {
+    resolve_proxy_query_token_ = 0;
+    resolve_proxy_timestamp_ = Timestamp();
+    for (auto &client : clients_) {
+      client.second.backoff.clear();
+      client.second.flood_control.clear_events();
+      client.second.flood_control_online.clear_events();
+      client_loop(client.second);
+    }
+
+    if (old_generation != network_generation_) {
+      loop();
+    }
+  }
+}
+void ConnectionCreator::on_online(bool online_flag) {
+  online_flag_ = online_flag;
+  if (online_flag_) {
+    for (auto &client : clients_) {
+      client.second.backoff.clear();
+      client.second.flood_control_online.clear_events();
+      client_loop(client.second);
+    }
+  }
+}
+
+void ConnectionCreator::on_mtproto_error(size_t hash) {
+  auto &client = clients_[hash];
+  client.hash = hash;
+  client.mtproto_error_flood_control.add_event(static_cast<int32>(Time::now_cached()));
+}
+
+void ConnectionCreator::request_raw_connection(DcId dc_id, bool allow_media_only, bool is_media,
+                                               Promise<std::unique_ptr<mtproto::RawConnection>> promise, size_t hash) {
+  auto &client = clients_[hash];
+  if (!client.inited) {
+    client.inited = true;
+    client.hash = hash;
+    client.dc_id = dc_id;
+    client.allow_media_only = allow_media_only;
+    client.is_media = is_media;
+  } else {
+    CHECK(client.hash == hash);
+    CHECK(client.dc_id == dc_id);
+    CHECK(client.allow_media_only == allow_media_only);
+    CHECK(client.is_media == is_media);
+  }
+  VLOG(connections) << tag("client", format::as_hex(client.hash)) << " " << dc_id << " "
+                    << tag("allow_media_only", allow_media_only);
+  client.queries.push_back(std::move(promise));
+
+  client_loop(client);
+}
+
+void ConnectionCreator::request_raw_connection_by_ip(IPAddress ip_address,
+                                                     Promise<std::unique_ptr<mtproto::RawConnection>> promise) {
+  auto r_socket_fd = SocketFd::open(ip_address);
+  if (r_socket_fd.is_error()) {
+    return promise.set_error(r_socket_fd.move_as_error());
+  }
+  auto raw_connection = std::make_unique<mtproto::RawConnection>(r_socket_fd.move_as_ok(),
+                                                                 mtproto::TransportType::ObfuscatedTcp, nullptr);
+  raw_connection->extra_ = network_generation_;
+  promise.set_value(std::move(raw_connection));
+}
+
+void ConnectionCreator::client_loop(ClientInfo &client) {
+  CHECK(client.hash != 0);
+  if (!network_flag_) {
+    return;
+  }
+  if (close_flag_) {
+    return;
+  }
+  bool use_socks5 = proxy_.type() == Proxy::Type::Socks5;
+  if (use_socks5 && !proxy_ip_address_.is_valid()) {
+    return;
+  }
+
+  VLOG(connections) << "client_loop: " << tag("client", format::as_hex(client.hash));
+
+  // Remove expired ready connections
+  client.ready_connections.erase(
+      std::remove_if(client.ready_connections.begin(), client.ready_connections.end(),
+                     [&, expire_at = Time::now_cached() - ClientInfo::READY_CONNECTIONS_TIMEOUT](auto &v) {
+                       bool drop = v.second < expire_at;
+                       VLOG_IF(connections, drop) << "Drop expired " << tag("connection", v.first.get());
+                       return drop;
+                     }),
+      client.ready_connections.end());
+
+  // Send ready connections into promises
+  {
+    auto begin = client.queries.begin();
+    auto it = begin;
+    while (it != client.queries.end() && !client.ready_connections.empty()) {
+      VLOG(connections) << "Send to promise " << tag("connection", client.ready_connections.back().first.get());
+      it->set_value(std::move(client.ready_connections.back().first));
+      client.ready_connections.pop_back();
+      it++;
+    }
+    client.queries.erase(begin, it);
+  }
+
+  // Main loop. Create new connections till needed
+  bool check_mode = client.checking_connections != 0;
+  while (true) {
+    // Check if we need new connections
+    if (client.queries.empty()) {
+      if (!client.ready_connections.empty()) {
+        client_set_timeout_at(client, Time::now() + ClientInfo::READY_CONNECTIONS_TIMEOUT);
+      }
+      return;
+    }
+    if (check_mode) {
+      if (client.checking_connections >= 3) {
+        return;
+      }
+    } else {
+      if (client.pending_connections >= client.queries.size()) {
+        return;
+      }
+    }
+
+    // Check flood
+    auto &flood_control = online_flag_ ? client.flood_control_online : client.flood_control;
+    auto wakeup_at = max(flood_control.get_wakeup_at(), client.mtproto_error_flood_control.get_wakeup_at());
+    if (!online_flag_) {
+      wakeup_at = max(wakeup_at, client.backoff.get_wakeup_at());
+    }
+    if (wakeup_at > Time::now()) {
+      return client_set_timeout_at(client, wakeup_at);
+    }
+    flood_control.add_event(static_cast<int32>(Time::now()));
+    if (!online_flag_) {
+      client.backoff.add_event(static_cast<int32>(Time::now()));
+    }
+
+    // Create new RawConnection
+    DcOptionsSet::Stat *stat{nullptr};
+    bool use_http{false};
+    string debug_str;
+
+    IPAddress mtproto_ip;
+
+    // sync part
+    auto r_socket_fd = [&, dc_id = client.dc_id, allow_media_only = client.allow_media_only]() -> Result<SocketFd> {
+      TRY_RESULT(info, dc_options_set_.find_connection(dc_id, allow_media_only, use_socks5));
+      stat = info.stat;
+      use_http = info.use_http;
+      check_mode |= info.should_check;
+
+      if (use_socks5) {
+        mtproto_ip = info.option->get_ip_address();
+        IPAddress socks5_ip;
+        TRY_STATUS(socks5_ip.init_host_port(proxy_.server(), proxy_.port()));
+        debug_str = PSTRING() << "Sock5 " << socks5_ip << " --> " << info.option->get_ip_address() << " " << dc_id
+                              << (info.use_http ? " HTTP" : "");
+        LOG(INFO) << "Create: " << debug_str;
+        return SocketFd::open(socks5_ip);
+      } else {
+        debug_str = PSTRING() << info.option->get_ip_address() << " " << dc_id << (info.use_http ? " HTTP" : "");
+        LOG(INFO) << "Create: " << debug_str;
+        return SocketFd::open(info.option->get_ip_address());
+      }
+    }();
+    if (r_socket_fd.is_error()) {
+      LOG(WARNING) << r_socket_fd.error();
+      if (stat) {
+        stat->on_error();  // TODO: different kind of error
+      }
+      return client_set_timeout_at(client, Time::now() + 0.1);
+    }
+
+    auto socket_fd = r_socket_fd.move_as_ok();
+    IPAddress debug_ip;
+    auto debug_ip_status = debug_ip.init_socket_address(socket_fd);
+    if (debug_ip_status.is_ok()) {
+      debug_str = PSTRING() << debug_str << debug_ip;
+    } else {
+      LOG(ERROR) << debug_ip_status;
+    }
+
+    client.pending_connections++;
+    if (check_mode) {
+      stat->on_check();
+      client.checking_connections++;
+    }
+
+    auto promise = PromiseCreator::lambda(
+        [actor_id = actor_id(this), check_mode, use_http, hash = client.hash, debug_str,
+         network_generation = network_generation_](Result<ConnectionData> r_connection_data) mutable {
+          send_closure(std::move(actor_id), &ConnectionCreator::client_create_raw_connection,
+                       std::move(r_connection_data), check_mode, use_http, hash, debug_str, network_generation);
+        });
+
+    auto stats_callback = std::make_unique<detail::StatsCallback>(
+        client.is_media ? media_net_stats_callback_ : common_net_stats_callback_, actor_id(this), client.hash, stat);
+
+    if (use_socks5) {
+      class Callback : public Socks5::Callback {
+       public:
+        explicit Callback(Promise<ConnectionData> promise, std::unique_ptr<detail::StatsCallback> stats_callback)
+            : promise_(std::move(promise)), stats_callback_(std::move(stats_callback)) {
+        }
+        void set_result(Result<SocketFd> result) override {
+          if (result.is_error()) {
+            connection_token_ = StateManager::ConnectionToken();
+            if (was_connected_) {
+              stats_callback_->on_error();
+            }
+            promise_.set_error(result.move_as_error());
+          } else {
+            ConnectionData data;
+            data.socket_fd = result.move_as_ok();
+            data.connection_token = std::move(connection_token_);
+            data.stats_callback = std::move(stats_callback_);
+            promise_.set_value(std::move(data));
+          }
+        }
+        void on_connected() override {
+          connection_token_ = StateManager::connection_proxy(G()->state_manager());
+          was_connected_ = true;
+        }
+
+       private:
+        Promise<ConnectionData> promise_;
+        StateManager::ConnectionToken connection_token_;
+        bool was_connected_{false};
+        std::unique_ptr<detail::StatsCallback> stats_callback_;
+      };
+      LOG(INFO) << "Start socks5: " << debug_str;
+      auto token = next_token();
+      children_[token] = create_actor<Socks5>(
+          "Socks5", std::move(socket_fd), mtproto_ip, proxy_.user().str(), proxy_.password().str(),
+          std::make_unique<Callback>(std::move(promise), std::move(stats_callback)), create_reference(token));
+    } else {
+      ConnectionData data;
+      data.socket_fd = std::move(socket_fd);
+      data.stats_callback = std::move(stats_callback);
+      promise.set_result(std::move(data));
+    }
+  }
+}
+
+void ConnectionCreator::client_create_raw_connection(Result<ConnectionData> r_connection_data, bool check_mode,
+                                                     bool use_http, size_t hash, string debug_str,
+                                                     uint32 network_generation) {
+  auto promise = PromiseCreator::lambda([actor_id = actor_id(this), hash, check_mode,
+                                         debug_str](Result<std::unique_ptr<mtproto::RawConnection>> result) mutable {
+    VLOG(connections) << "Ready " << debug_str << " " << tag("checked", check_mode) << tag("ok", result.is_ok());
+    send_closure(std::move(actor_id), &ConnectionCreator::client_add_connection, hash, std::move(result), check_mode);
+  });
+
+  if (r_connection_data.is_error()) {
+    return promise.set_error(r_connection_data.move_as_error());
+  }
+
+  auto connection_data = r_connection_data.move_as_ok();
+  auto raw_connection = std::make_unique<mtproto::RawConnection>(
+      std::move(connection_data.socket_fd),
+      use_http ? mtproto::TransportType::Http : mtproto::TransportType::ObfuscatedTcp,
+      std::move(connection_data.stats_callback));
+  raw_connection->set_connection_token(std::move(connection_data.connection_token));
+
+  raw_connection->extra_ = network_generation;
+  raw_connection->debug_str_ = debug_str;
+
+  if (check_mode) {
+    VLOG(connections) << "Start check: " << debug_str;
+    auto token = next_token();
+    children_[token] = create_actor<detail::PingActor>("PingActor", std::move(raw_connection), std::move(promise),
+                                                       create_reference(token));
+  } else {
+    promise.set_value(std::move(raw_connection));
+  }
+}
+
+void ConnectionCreator::client_set_timeout_at(ClientInfo &client, double wakeup_at) {
+  if (!client.slot.has_event()) {
+    client.slot.set_event(self_closure(this, &ConnectionCreator::client_wakeup, client.hash));
+  }
+  client.slot.set_timeout_at(wakeup_at);
+  VLOG(connections) << tag("client", format::as_hex(client.hash)) << " set timeout in "
+                    << wakeup_at - Time::now_cached();
+}
+
+void ConnectionCreator::client_add_connection(size_t hash,
+                                              Result<std::unique_ptr<mtproto::RawConnection>> r_raw_connection,
+                                              bool check_flag) {
+  auto &client = clients_[hash];
+  CHECK(client.pending_connections > 0);
+  client.pending_connections--;
+  if (check_flag) {
+    CHECK(client.checking_connections > 0);
+    client.checking_connections--;
+  }
+  if (r_raw_connection.is_ok()) {
+    client.backoff.clear();
+    client.ready_connections.push_back(std::make_pair(r_raw_connection.move_as_ok(), Time::now_cached()));
+  }
+  client_loop(client);
+}
+
+void ConnectionCreator::client_wakeup(size_t hash) {
+  LOG(INFO) << tag("hash", format::as_hex(hash)) << " wakeup";
+  client_loop(clients_[hash]);
+}
+
+void ConnectionCreator::on_dc_options(DcOptions new_dc_options) {
+  LOG(INFO) << "SAVE " << new_dc_options;
+  G()->td_db()->get_binlog_pmc()->set("dc_options", serialize(new_dc_options));
+  dc_options_set_.reset();
+  dc_options_set_.add_dc_options(get_default_dc_options(G()->is_test_dc()));
+#if !TD_EMSCRIPTEN  // FIXME
+  dc_options_set_.add_dc_options(std::move(new_dc_options));
+#endif
+}
+
+void ConnectionCreator::on_dc_update(DcId dc_id, string ip_port, Promise<> promise) {
+  promise.set_result([&]() -> Result<> {
+    if (!dc_id.is_exact()) {
+      return Status::Error("Invalid dc_id");
+    }
+    IPAddress ip_address;
+    TRY_STATUS(ip_address.init_host_port(ip_port));
+    DcOptions options;
+    options.dc_options.emplace_back(dc_id, ip_address);
+    send_closure(G()->config_manager(), &ConfigManager::on_dc_options_update, std::move(options));
+    return Unit();
+  }());
+}
+
+void ConnectionCreator::start_up() {
+  class StateCallback : public StateManager::Callback {
+   public:
+    explicit StateCallback(ActorId<ConnectionCreator> session) : session_(std::move(session)) {
+    }
+    bool on_network(NetType network_type, uint32 generation) override {
+      send_closure(session_, &ConnectionCreator::on_network, network_type != NetType::None, generation);
+      return session_.is_alive();
+    }
+    bool on_online(bool online_flag) override {
+      send_closure(session_, &ConnectionCreator::on_online, online_flag);
+      return session_.is_alive();
+    }
+
+   private:
+    ActorId<ConnectionCreator> session_;
+  };
+  send_closure(G()->state_manager(), &StateManager::add_callback, make_unique<StateCallback>(actor_id(this)));
+
+  auto serialized_dc_options = G()->td_db()->get_binlog_pmc()->get("dc_options");
+  DcOptions dc_options;
+  auto status = unserialize(dc_options, serialized_dc_options);
+  if (status.is_error()) {
+    on_dc_options(DcOptions());
+  } else {
+    on_dc_options(std::move(dc_options));
+  }
+
+  auto log_event_proxy = G()->td_db()->get_binlog_pmc()->get("proxy");
+  if (!log_event_proxy.empty()) {
+    Proxy proxy;
+    log_event_parse(proxy, log_event_proxy).ensure();
+    set_proxy_impl(std::move(proxy), true);
+  }
+
+  get_host_by_name_actor_ =
+      create_actor_on_scheduler<GetHostByNameActor>("GetHostByNameActor", G()->get_gc_scheduler_id(), 29 * 60, 0);
+
+  ref_cnt_guard_ = create_reference(-1);
+
+  loop();
+}
+
+void ConnectionCreator::hangup_shared() {
+  ref_cnt_--;
+  children_.erase(get_link_token());
+  if (ref_cnt_ == 0) {
+    stop();
+  }
+}
+
+ActorShared<ConnectionCreator> ConnectionCreator::create_reference(int64 token) {
+  CHECK(token != 0);
+  ref_cnt_++;
+  return actor_shared(this, token);
+}
+
+void ConnectionCreator::hangup() {
+  close_flag_ = true;
+  ref_cnt_guard_.reset();
+  for (auto &child : children_) {
+    child.second.reset();
+  }
+}
+
+DcOptions ConnectionCreator::get_default_dc_options(bool is_test) {
+  DcOptions res;
+  auto add_ip_ports = [&res](int32 dc_id, const vector<string> &ips, const vector<int> &ports, bool is_ipv6 = false) {
+    IPAddress ip_address;
+    for (auto &ip : ips) {
+      for (auto port : ports) {
+        if (is_ipv6) {
+          ip_address.init_ipv6_port(ip, port).ensure();
+        } else {
+          ip_address.init_ipv4_port(ip, port).ensure();
+        }
+        res.dc_options.emplace_back(DcId::internal(dc_id), ip_address);
+      }
+    }
+  };
+  vector<int> ports = {443, 80, 5222};
+  if (is_test) {
+    add_ip_ports(1, {"149.154.175.10"}, ports);
+    add_ip_ports(2, {"149.154.167.40"}, ports);
+    add_ip_ports(3, {"149.154.175.117"}, ports);
+
+    add_ip_ports(1, {"2001:b28:f23d:f001::e"}, ports, true);
+    add_ip_ports(2, {"2001:67c:4e8:f002::e"}, ports, true);
+    add_ip_ports(3, {"2001:b28:f23d:f003::e"}, ports, true);
+  } else {
+    add_ip_ports(1, {"149.154.175.50"}, ports);
+    add_ip_ports(2, {"149.154.167.51"}, ports);
+    add_ip_ports(3, {"149.154.175.100"}, ports);
+    add_ip_ports(4, {"149.154.167.91"}, ports);
+    add_ip_ports(5, {"149.154.171.5"}, ports);
+
+    add_ip_ports(1, {"2001:b28:f23d:f001::a"}, ports, true);
+    add_ip_ports(2, {"2001:67c:4e8:f002::a"}, ports, true);
+    add_ip_ports(3, {"2001:b28:f23d:f003::a"}, ports, true);
+    add_ip_ports(4, {"2001:67c:4e8:f004::a"}, ports, true);
+    add_ip_ports(5, {"2001:b28:f23f:f005::a"}, ports, true);
+  }
+  return res;
+}
+
+void ConnectionCreator::loop() {
+  if (!network_flag_) {
+    return;
+  }
+  if (proxy_.type() != Proxy::Type::Socks5) {
+    return;
+  }
+  if (resolve_proxy_query_token_ != 0) {
+    return;
+  }
+  if (resolve_proxy_timestamp_ && !resolve_proxy_timestamp_.is_in_past()) {
+    set_timeout_at(resolve_proxy_timestamp_.at());
+    return;
+  }
+  resolve_proxy_query_token_ = next_token();
+  send_closure(
+      get_host_by_name_actor_, &GetHostByNameActor::run, proxy_.server().str(), proxy_.port(),
+      PromiseCreator::lambda([actor_id = create_reference(resolve_proxy_query_token_)](Result<IPAddress> result) {
+        send_closure(std::move(actor_id), &ConnectionCreator::on_proxy_resolved, std::move(result), false);
+      }));
+}
+
+void ConnectionCreator::on_proxy_resolved(Result<IPAddress> r_ip_address, bool dummy) {
+  SCOPE_EXIT {
+    loop();
+  };
+  if (get_link_token() != resolve_proxy_query_token_) {
+    return;
+  }
+  resolve_proxy_query_token_ = 0;
+  if (r_ip_address.is_error()) {
+    resolve_proxy_timestamp_ = Timestamp::in(5 * 60);
+    return;
+  }
+  proxy_ip_address_ = r_ip_address.move_as_ok();
+  resolve_proxy_timestamp_ = Timestamp::in(29 * 60);
+  for (auto &client : clients_) {
+    client_loop(client.second);
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/ConnectionCreator.h b/libs/tdlib/td/td/telegram/net/ConnectionCreator.h
new file mode 100644
index 0000000000..1c5dbc8d9f
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/ConnectionCreator.h
@@ -0,0 +1,255 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+
+#include "td/telegram/net/DcOptions.h"
+#include "td/telegram/net/DcOptionsSet.h"
+#include "td/telegram/StateManager.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+#include "td/actor/SignalSlot.h"
+
+#include "td/net/NetStats.h"
+
+#include "td/utils/FloodControlStrict.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/IPAddress.h"
+#include "td/utils/port/SocketFd.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/Time.h"
+
+#include <map>
+#include <memory>
+#include <utility>
+
+namespace td {
+namespace mtproto {
+class RawConnection;
+}  // namespace mtproto
+namespace detail {
+class StatsCallback;
+}
+class GetHostByNameActor;
+}  // namespace td
+
+namespace td {
+
+class Proxy {
+ public:
+  tl_object_ptr<td_api::Proxy> as_td_api() const {
+    switch (type_) {
+      case Type::None:
+        return make_tl_object<td_api::proxyEmpty>();
+      case Type::Socks5:
+        return make_tl_object<td_api::proxySocks5>(server_, port_, user_, password_);
+    }
+    UNREACHABLE();
+    return nullptr;
+  }
+
+  static Proxy from_td_api(const tl_object_ptr<td_api::Proxy> &proxy) {
+    if (proxy == nullptr) {
+      return Proxy();
+    }
+
+    switch (proxy->get_id()) {
+      case td_api::proxyEmpty::ID:
+        return Proxy();
+      case td_api::proxySocks5::ID: {
+        auto &socks5_proxy = static_cast<const td_api::proxySocks5 &>(*proxy);
+        return Proxy::socks5(socks5_proxy.server_, socks5_proxy.port_, socks5_proxy.username_, socks5_proxy.password_);
+      }
+    }
+    UNREACHABLE();
+    return Proxy();
+  }
+
+  static Proxy socks5(string server, int32 port, string user, string password) {
+    Proxy proxy;
+    proxy.type_ = Type::Socks5;
+    proxy.server_ = std::move(server);
+    proxy.port_ = std::move(port);
+    proxy.user_ = std::move(user);
+    proxy.password_ = std::move(password);
+    return proxy;
+  }
+
+  CSlice server() const {
+    return server_;
+  }
+
+  int32 port() const {
+    return port_;
+  }
+
+  CSlice user() const {
+    return user_;
+  }
+
+  CSlice password() const {
+    return password_;
+  }
+
+  enum class Type { None, Socks5 };
+  Type type() const {
+    return type_;
+  }
+
+  template <class T>
+  void parse(T &parser);
+
+  template <class T>
+  void store(T &storer) const;
+
+ private:
+  Type type_{Type::None};
+  string server_;
+  int32 port_ = 0;
+  string user_;
+  string password_;
+};
+
+inline bool operator==(const Proxy &lhs, const Proxy &rhs) {
+  return lhs.type() == rhs.type() && lhs.server() == rhs.server() && lhs.port() == rhs.port() &&
+         lhs.user() == rhs.user() && lhs.password() == rhs.password();
+}
+
+inline bool operator!=(const Proxy &lhs, const Proxy &rhs) {
+  return !(lhs == rhs);
+}
+
+class ConnectionCreator : public Actor {
+ public:
+  explicit ConnectionCreator(ActorShared<> parent);
+  ConnectionCreator(ConnectionCreator &&other);
+  ConnectionCreator &operator=(ConnectionCreator &&other);
+  ~ConnectionCreator() override;
+  void on_dc_options(DcOptions new_dc_options);
+  void on_dc_update(DcId dc_id, string ip_port, Promise<> promise);
+  void on_mtproto_error(size_t hash);
+  void request_raw_connection(DcId dc_id, bool allow_media_only, bool is_media,
+                              Promise<std::unique_ptr<mtproto::RawConnection>> promise, size_t hash = 0);
+  void request_raw_connection_by_ip(IPAddress ip_address, Promise<std::unique_ptr<mtproto::RawConnection>> promise);
+
+  void set_net_stats_callback(std::shared_ptr<NetStatsCallback> common_callback,
+                              std::shared_ptr<NetStatsCallback> media_callback);
+
+  void set_proxy(Proxy proxy);
+  void get_proxy(Promise<Proxy> promise);
+
+ private:
+  ActorShared<> parent_;
+  DcOptionsSet dc_options_set_;
+  bool network_flag_ = false;
+  uint32 network_generation_ = 0;
+  bool online_flag_ = false;
+
+  Proxy proxy_;
+  ActorOwn<GetHostByNameActor> get_host_by_name_actor_;
+  IPAddress proxy_ip_address_;
+  Timestamp resolve_proxy_timestamp_;
+  uint64 resolve_proxy_query_token_{0};
+
+  struct ClientInfo {
+    class Backoff {
+#if TD_ANDROID || TD_DARWIN_IOS || TD_DARWIN_WATCH_OS || TD_TIZEN
+      static constexpr int32 MAX_BACKOFF = 300;
+#else
+      static constexpr int32 MAX_BACKOFF = 16;
+#endif
+
+     public:
+      void add_event(int32 now) {
+        wakeup_at_ = now + next_delay_;
+        next_delay_ = min(MAX_BACKOFF, next_delay_ * 2);
+      }
+      int32 get_wakeup_at() const {
+        return wakeup_at_;
+      }
+      void clear() {
+        *this = {};
+      }
+
+     private:
+      int32 wakeup_at_{0};
+      int32 next_delay_ = 1;
+    };
+    ClientInfo();
+
+    Backoff backoff;
+    FloodControlStrict flood_control;
+    FloodControlStrict flood_control_online;
+    FloodControlStrict mtproto_error_flood_control;
+    Slot slot;
+    size_t pending_connections{0};
+    size_t checking_connections{0};
+    std::vector<std::pair<std::unique_ptr<mtproto::RawConnection>, double>> ready_connections;
+    std::vector<Promise<std::unique_ptr<mtproto::RawConnection>>> queries;
+
+    static constexpr double READY_CONNECTIONS_TIMEOUT = 10;
+
+    bool inited{false};
+    size_t hash{0};
+    DcId dc_id;
+    bool allow_media_only;
+    bool is_media;
+  };
+  std::map<size_t, ClientInfo> clients_;
+
+  std::shared_ptr<NetStatsCallback> media_net_stats_callback_;
+  std::shared_ptr<NetStatsCallback> common_net_stats_callback_;
+
+  ActorShared<> ref_cnt_guard_;
+  int ref_cnt_{0};
+  ActorShared<ConnectionCreator> create_reference(int64 token);
+  bool close_flag_{false};
+  int64 current_token_ = 0;
+  std::map<int64, ActorShared<>> children_;
+
+  int64 next_token() {
+    return ++current_token_;
+  }
+  void set_proxy_impl(Proxy proxy, bool from_db);
+
+  void start_up() override;
+  void hangup_shared() override;
+  void hangup() override;
+  void loop() override;
+
+  void save_dc_options();
+  Result<SocketFd> do_request_connection(DcId dc_id, bool allow_media_only);
+  Result<std::pair<std::unique_ptr<mtproto::RawConnection>, bool>> do_request_raw_connection(DcId dc_id,
+                                                                                             bool allow_media_only,
+                                                                                             bool is_media,
+                                                                                             size_t hash);
+
+  void on_network(bool network_flag, uint32 network_generation);
+  void on_online(bool online_flag);
+
+  void client_wakeup(size_t hash);
+  void client_loop(ClientInfo &client);
+  struct ConnectionData {
+    SocketFd socket_fd;
+    StateManager::ConnectionToken connection_token;
+    std::unique_ptr<detail::StatsCallback> stats_callback;
+  };
+  void client_create_raw_connection(Result<ConnectionData> r_connection_data, bool check_mode, bool use_http,
+                                    size_t hash, string debug_str, uint32 network_generation);
+  void client_add_connection(size_t hash, Result<std::unique_ptr<mtproto::RawConnection>> r_raw_connection,
+                             bool check_flag);
+  void client_set_timeout_at(ClientInfo &client, double wakeup_at);
+
+  void on_proxy_resolved(Result<IPAddress> ip_address, bool dummy);
+
+  static DcOptions get_default_dc_options(bool is_test);
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/DcAuthManager.cpp b/libs/tdlib/td/td/telegram/net/DcAuthManager.cpp
new file mode 100644
index 0000000000..dd3776a449
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/DcAuthManager.cpp
@@ -0,0 +1,217 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/DcAuthManager.h"
+
+#include "td/actor/actor.h"
+
+#include "td/telegram/ConfigShared.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/net/AuthDataShared.h"
+#include "td/telegram/net/NetQuery.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+#include "td/telegram/UniqueId.h"
+
+#include "td/telegram/telegram_api.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+
+#include <algorithm>
+#include <limits>
+
+namespace td {
+
+DcAuthManager::DcAuthManager(ActorShared<> parent) {
+  parent_ = std::move(parent);
+  auto s_main_dc_id = G()->td_db()->get_binlog_pmc()->get("main_dc_id");
+  if (!s_main_dc_id.empty()) {
+    main_dc_id_ = DcId::internal(to_integer<int32>(s_main_dc_id));
+  }
+}
+
+void DcAuthManager::add_dc(std::shared_ptr<AuthDataShared> auth_data) {
+  VLOG(dc) << "Register " << auth_data->dc_id();
+  class Listener : public AuthDataShared::Listener {
+   public:
+    explicit Listener(ActorShared<DcAuthManager> dc_manager) : dc_manager_(std::move(dc_manager)) {
+    }
+    bool notify() override {
+      if (!dc_manager_.is_alive()) {
+        return false;
+      }
+      send_closure(dc_manager_, &DcAuthManager::update_auth_state);
+      return true;
+    }
+
+   private:
+    ActorShared<DcAuthManager> dc_manager_;
+  };
+
+  DcInfo info;
+  info.dc_id = auth_data->dc_id();
+  CHECK(info.dc_id.is_exact());
+  info.shared_auth_data = std::move(auth_data);
+  auto state_was_auth = info.shared_auth_data->get_auth_state();
+  info.auth_state = state_was_auth.first;
+  was_auth_ |= state_was_auth.second;
+  if (!main_dc_id_.is_exact()) {
+    main_dc_id_ = info.dc_id;
+  }
+  info.shared_auth_data->add_auth_key_listener(std::make_unique<Listener>(actor_shared(this, info.dc_id.get_raw_id())));
+  dcs_.emplace_back(std::move(info));
+  loop();
+}
+
+void DcAuthManager::update_main_dc(DcId new_main_dc_id) {
+  main_dc_id_ = new_main_dc_id;
+  loop();
+}
+
+DcAuthManager::DcInfo &DcAuthManager::get_dc(int32 dc_id) {
+  auto *dc = find_dc(dc_id);
+  CHECK(dc);
+  return *dc;
+}
+DcAuthManager::DcInfo *DcAuthManager::find_dc(int32 dc_id) {
+  auto it = std::find_if(dcs_.begin(), dcs_.end(), [&](auto &x) { return x.dc_id.get_raw_id() == dc_id; });
+  if (it == dcs_.end()) {
+    return nullptr;
+  }
+  return &*it;
+}
+
+void DcAuthManager::update_auth_state() {
+  int32 dc_id = narrow_cast<int32>(get_link_token());
+  auto &dc = get_dc(dc_id);
+  auto state_was_auth = dc.shared_auth_data->get_auth_state();
+  VLOG(dc) << "Update dc auth state " << tag("dc_id", dc_id) << tag("old_auth_state", dc.auth_state)
+           << tag("new_auth_state", state_was_auth.first);
+  dc.auth_state = state_was_auth.first;
+  was_auth_ |= state_was_auth.second;
+
+  loop();
+}
+
+void DcAuthManager::on_result(NetQueryPtr result) {
+  int32 dc_id = narrow_cast<int32>(get_link_token());
+  auto &dc = get_dc(dc_id);
+  CHECK(dc.wait_id == result->id());
+  dc.wait_id = std::numeric_limits<decltype(dc.wait_id)>::max();
+  switch (dc.state) {
+    case DcInfo::State::Import: {
+      if (result->is_error()) {
+        LOG(WARNING) << "DC auth_exportAuthorization error: " << result->error();
+        dc.state = DcInfo::State::Export;
+        break;
+      }
+      auto result_auth_exported = fetch_result<telegram_api::auth_exportAuthorization>(result->ok());
+      if (result_auth_exported.is_error()) {
+        LOG(WARNING) << "Failed to parse result to auth_exportAuthorization: " << result_auth_exported.error();
+        dc.state = DcInfo::State::Export;
+        break;
+      }
+      dc.export_id = result_auth_exported.ok()->id_;
+      dc.export_bytes = std::move(result_auth_exported.ok()->bytes_);
+      break;
+    }
+    case DcInfo::State::BeforeOk: {
+      if (result->is_error()) {
+        LOG(WARNING) << "DC authImport error: " << result->error();
+        dc.state = DcInfo::State::Export;
+        break;
+      }
+      auto result_auth = fetch_result<telegram_api::auth_importAuthorization>(result->ok());
+      if (result_auth.is_error()) {
+        LOG(WARNING) << "Failed to parse result to auth_importAuthorization: " << result_auth.error();
+        dc.state = DcInfo::State::Export;
+        break;
+      }
+      dc.state = DcInfo::State::Ok;
+      break;
+    }
+    default:
+      UNREACHABLE();
+  }
+  result->clear();
+  loop();
+}
+
+void DcAuthManager::dc_loop(DcInfo &dc) {
+  VLOG(dc) << "dc_loop " << dc.dc_id << " " << dc.auth_state;
+  if (dc.auth_state == AuthState::OK) {
+    return;
+  }
+  CHECK(dc.shared_auth_data);
+  switch (dc.state) {
+    case DcInfo::State::Waiting: {
+      // wait for timeout
+      //      break;
+    }
+    case DcInfo::State::Export: {
+      // send auth.exportAuthorization to auth_dc
+      VLOG(dc) << "Send exportAuthorization to " << dc.dc_id;
+      auto id = UniqueId::next();
+      G()->net_query_dispatcher().dispatch_with_callback(
+          G()->net_query_creator().create(
+              id, create_storer(telegram_api::auth_exportAuthorization(dc.dc_id.get_raw_id())), DcId::main(),
+              NetQuery::Type::Common, NetQuery::AuthFlag::On, NetQuery::GzipFlag::On, 60 * 60 * 24),
+          actor_shared(this, dc.dc_id.get_raw_id()));
+      dc.wait_id = id;
+      dc.export_id = -1;
+      dc.state = DcInfo::State::Import;
+      break;
+    }
+    case DcInfo::State::Import: {
+      // send auth.importAuthorization to dc
+      if (dc.export_id == -1) {
+        break;
+      }
+      uint64 id = UniqueId::next();
+      VLOG(dc) << "Send importAuthorization to " << dc.dc_id;
+      G()->net_query_dispatcher().dispatch_with_callback(
+          G()->net_query_creator().create(
+              id, create_storer(telegram_api::auth_importAuthorization(dc.export_id, std::move(dc.export_bytes))),
+              dc.dc_id, NetQuery::Type::Common, NetQuery::AuthFlag::Off, NetQuery::GzipFlag::On, 60 * 60 * 24),
+          actor_shared(this, dc.dc_id.get_raw_id()));
+      dc.wait_id = id;
+      dc.state = DcInfo::State::BeforeOk;
+      break;
+    }
+    case DcInfo::State::BeforeOk: {
+      break;
+    }
+    case DcInfo::State::Ok: {
+      break;
+    }
+  }
+}
+
+void DcAuthManager::loop() {
+  if (close_flag_) {
+    VLOG(dc) << "Skip loop because close_flag";
+    return;
+  }
+  if (!main_dc_id_.is_exact()) {
+    VLOG(dc) << "Skip loop because main_dc_id is unknown";
+    return;
+  }
+  auto main_dc = find_dc(main_dc_id_.get_raw_id());
+  if (!main_dc || main_dc->auth_state != AuthState::OK) {
+    if (was_auth_) {
+      G()->shared_config().set_option_boolean("auth", false);
+    }
+    VLOG(dc) << "Skip loop because auth state of main dc " << main_dc_id_.get_raw_id() << " is "
+             << (main_dc != nullptr ? (PSTRING() << main_dc->auth_state) : "unknown");
+
+    return;
+  }
+  for (auto &dc : dcs_) {
+    dc_loop(dc);
+  }
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/DcAuthManager.h b/libs/tdlib/td/td/telegram/net/DcAuthManager.h
new file mode 100644
index 0000000000..a8710f6102
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/DcAuthManager.h
@@ -0,0 +1,58 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/Global.h"
+#include "td/telegram/net/AuthDataShared.h"
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/actor/actor.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+
+#include <memory>
+
+namespace td {
+class DcAuthManager : public NetQueryCallback {
+ public:
+  explicit DcAuthManager(ActorShared<> parent);
+
+  void add_dc(std::shared_ptr<AuthDataShared> auth_data);
+  void update_main_dc(DcId new_main_dc_id);
+
+ private:
+  struct DcInfo {
+    DcId dc_id;
+    std::shared_ptr<AuthDataShared> shared_auth_data;
+    AuthState auth_state;
+
+    enum class State { Waiting, Export, Import, BeforeOk, Ok };
+    State state = State::Waiting;
+    uint64 wait_id;
+    int32 export_id;
+    BufferSlice export_bytes;
+  };
+
+  ActorShared<> parent_;
+
+  std::vector<DcInfo> dcs_;
+  bool was_auth_ = false;
+  DcId main_dc_id_;
+  bool close_flag_ = false;
+
+  DcInfo &get_dc(int32 dc_id);
+  DcInfo *find_dc(int32 dc_id);
+
+  void update_auth_state();
+
+  void on_result(NetQueryPtr result) override;
+  void dc_loop(DcInfo &dc);
+
+  void loop() override;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/DcId.h b/libs/tdlib/td/td/telegram/net/DcId.h
new file mode 100644
index 0000000000..f258d34014
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/DcId.h
@@ -0,0 +1,102 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/utils/logging.h"
+#include "td/utils/StringBuilder.h"
+
+namespace td {
+class DcId {
+ public:
+  DcId() = default;
+  DcId(const DcId &other) = default;
+
+  static bool is_valid(int32 dc_id) {
+    return 1 <= dc_id && dc_id <= 1000;
+  }
+  static DcId main() {
+    return DcId{MainDc, false};
+  }
+  static DcId invalid() {
+    return DcId{Invalid, false};
+  }
+  static DcId internal(int32 id) {
+    CHECK(is_valid(id));
+    return DcId{id, false};
+  }
+  static DcId external(int32 id) {
+    CHECK(is_valid(id));
+    return DcId{id, true};
+  }
+  static DcId empty() {
+    return {};
+  }
+  static DcId from_value(int32 value) {
+    return DcId{value, false};
+  }
+
+  bool is_empty() const {
+    return !is_valid();
+  }
+  bool is_main() const {
+    return dc_id_ == MainDc;
+  }
+  int32 get_raw_id() const {
+    CHECK(is_exact());
+    return dc_id_;
+  }
+  int32 get_value() const {
+    return dc_id_;
+  }
+  bool is_internal() const {
+    return !is_external();
+  }
+  bool is_external() const {
+    return is_external_;
+  }
+  bool is_exact() const {
+    return dc_id_ > 0;
+  }
+  bool operator==(DcId other) const {
+    return dc_id_ == other.dc_id_ && is_external_ == other.is_external_;
+  }
+  bool operator<(DcId other) const {
+    return dc_id_ < other.dc_id_;
+  }
+  bool operator!=(DcId other) const {
+    return !(*this == other);
+  }
+
+ private:
+  enum { Empty = 0, MainDc = -1, Invalid = -2 };
+  int32 dc_id_{Empty};
+  bool is_external_{false};
+
+  DcId(int32 dc_id, bool is_external) : dc_id_(dc_id), is_external_(is_external) {
+  }
+
+  bool is_valid() const {
+    return is_exact() || is_main();
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &sb, const DcId &dc_id) {
+  sb << "DcId{";
+  if (dc_id.is_empty()) {
+    sb << "empty";
+  } else if (dc_id.is_main()) {
+    sb << "main";
+  } else {
+    sb << dc_id.get_raw_id();
+    if (dc_id.is_external()) {
+      sb << " external";
+    }
+  }
+  sb << "}";
+  return sb;
+}
+
+};  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/DcOptions.h b/libs/tdlib/td/td/telegram/net/DcOptions.h
new file mode 100644
index 0000000000..9ce5aeb40f
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/DcOptions.h
@@ -0,0 +1,207 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/net/DcId.h"
+
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/IPAddress.h"
+#include "td/utils/Slice.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+class DcOption {
+  // do not forget to update PrintFlags
+  enum Flags { IPv6 = 1, MediaOnly = 2, ObfuscatedTcpOnly = 4, Cdn = 8, Static = 16 };
+
+  int32 flags = 0;
+  DcId dc_id;
+  IPAddress ip_address;
+
+  struct PrintFlags {
+    int32 flags;
+  };
+
+  bool is_ipv6() const {
+    return (flags & Flags::IPv6) != 0;
+  }
+
+ public:
+  DcOption() = default;
+
+  DcOption(DcId dc_id, const IPAddress &ip_address)
+      : flags(ip_address.is_ipv4() ? 0 : IPv6), dc_id(dc_id), ip_address(ip_address) {
+  }
+
+  explicit DcOption(const telegram_api::dcOption &option) {
+    auto ip = option.ip_address_;
+    auto port = option.port_;
+    flags = 0;
+    if (!DcId::is_valid(option.id_)) {
+      dc_id = DcId::invalid();
+      return;
+    }
+
+    if (option.cdn_) {
+      dc_id = DcId::external(option.id_);
+      flags |= Flags::Cdn;
+    } else {
+      dc_id = DcId::internal(option.id_);
+    }
+    if (option.ipv6_) {
+      flags |= Flags::IPv6;
+    }
+    if (option.media_only_) {
+      flags |= Flags::MediaOnly;
+    }
+    if (option.tcpo_only_) {
+      flags |= Flags::ObfuscatedTcpOnly;
+    }
+    if (option.static_) {
+      flags |= Flags::Static;
+    }
+    init_ip_address(ip, port);
+  }
+
+  DcOption(DcId new_dc_id, const telegram_api::ipPort &ip_port) {
+    dc_id = new_dc_id;
+    init_ip_address(IPAddress::ipv4_to_str(ip_port.ipv4_), ip_port.port_);
+  }
+
+  DcId get_dc_id() const {
+    return dc_id;
+  }
+
+  const IPAddress &get_ip_address() const {
+    return ip_address;
+  }
+
+  bool is_media_only() const {
+    return (flags & Flags::MediaOnly) != 0;
+  }
+
+  bool is_obfuscated_tcp_only() const {
+    return (flags & Flags::ObfuscatedTcpOnly) != 0;
+  }
+
+  bool is_static() const {
+    return (flags & Flags::Static) != 0;
+  }
+
+  bool is_valid() const {
+    return ip_address.is_valid() && dc_id.is_exact();
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    storer.store_int(flags);
+    storer.store_int(dc_id.get_raw_id());
+    CHECK(ip_address.is_valid());
+    storer.store_string(ip_address.get_ip_str());
+    storer.store_int(ip_address.get_port());
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    flags = parser.fetch_int();
+    auto raw_dc_id = parser.fetch_int();
+    if (flags & Flags::Cdn) {
+      dc_id = DcId::external(raw_dc_id);
+    } else {
+      dc_id = DcId::internal(raw_dc_id);
+    }
+    auto ip = parser.template fetch_string<std::string>();
+    auto port = parser.fetch_int();
+    init_ip_address(ip, port);
+  }
+
+  friend bool operator==(const DcOption &lhs, const DcOption &rhs);
+
+  friend StringBuilder &operator<<(StringBuilder &sb, const DcOption::PrintFlags &flags);
+
+  friend StringBuilder &operator<<(StringBuilder &sb, const DcOption &dc_option);
+
+ private:
+  void init_ip_address(CSlice ip, int32 port) {
+    if (is_ipv6()) {
+      ip_address.init_ipv6_port(ip, port).ignore();
+    } else {
+      ip_address.init_ipv4_port(ip, port).ignore();
+    }
+  }
+};
+
+inline bool operator==(const DcOption &lhs, const DcOption &rhs) {
+  return lhs.dc_id == rhs.dc_id && lhs.ip_address == rhs.ip_address && lhs.flags == rhs.flags;
+}
+
+inline StringBuilder &operator<<(StringBuilder &sb, const DcOption::PrintFlags &flags) {
+  if ((flags.flags & DcOption::Flags::ObfuscatedTcpOnly) != 0) {
+    sb << "(ObfuscatedTcpOnly)";
+  }
+  if ((flags.flags & DcOption::Flags::MediaOnly) != 0) {
+    sb << "(MediaOnly)";
+  }
+  if ((flags.flags & DcOption::Flags::IPv6) != 0) {
+    sb << "(IPv6)";
+  }
+  if ((flags.flags & DcOption::Flags::Cdn) != 0) {
+    sb << "(Cdn)";
+  }
+  if ((flags.flags & DcOption::Flags::Static) != 0) {
+    sb << "(Static)";
+  }
+  return sb;
+}
+
+inline StringBuilder &operator<<(StringBuilder &sb, const DcOption &dc_option) {
+  return sb << tag("DcOption", format::concat(dc_option.dc_id, tag("ip", dc_option.ip_address.get_ip_str()),
+                                              tag("port", dc_option.ip_address.get_port()),
+                                              tag("flags", DcOption::PrintFlags{dc_option.flags})));
+}
+
+class DcOptions {
+ public:
+  DcOptions() = default;
+  explicit DcOptions(const std::vector<tl_object_ptr<telegram_api::dcOption>> &server_dc_options) {
+    for (auto &dc_option : server_dc_options) {
+      DcOption option(*dc_option);
+      if (option.is_valid()) {
+        dc_options.push_back(std::move(option));
+      }
+    }
+  }
+  explicit DcOptions(const telegram_api::help_configSimple &config_simple) {
+    auto dc_id = DcId::is_valid(config_simple.dc_id_) ? DcId::internal(config_simple.dc_id_) : DcId();
+    for (auto &ip_port : config_simple.ip_port_list_) {
+      DcOption option(dc_id, *ip_port);
+      if (option.is_valid()) {
+        dc_options.push_back(std::move(option));
+      }
+    }
+  }
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    ::td::store(dc_options, storer);
+  }
+
+  template <class ParserT>
+  void parse(ParserT &parser) {
+    ::td::parse(dc_options, parser);
+  }
+
+  std::vector<DcOption> dc_options;
+};
+inline StringBuilder &operator<<(StringBuilder &sb, const DcOptions &dc_options) {
+  return sb << "DcOptions" << format::as_array(dc_options.dc_options);
+}
+};  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/DcOptionsSet.cpp b/libs/tdlib/td/td/telegram/net/DcOptionsSet.cpp
new file mode 100644
index 0000000000..4aefd3b7f7
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/DcOptionsSet.cpp
@@ -0,0 +1,158 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/DcOptionsSet.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+
+#include <algorithm>
+#include <set>
+#include <utility>
+
+namespace td {
+
+void DcOptionsSet::add_dc_options(DcOptions dc_options) {
+  std::vector<DcOptionId> new_ordered_options;
+  for (auto &option : dc_options.dc_options) {
+    auto *info = register_dc_option(std::move(option));
+    new_ordered_options.push_back(DcOptionId{info->pos});
+  }
+
+  std::set<DcOptionId> new_ordered_options_set(new_ordered_options.begin(), new_ordered_options.end());
+  for (auto option_id : ordered_options_) {
+    if (!new_ordered_options_set.count(option_id)) {
+      new_ordered_options.push_back(option_id);
+    }
+  }
+
+  ordered_options_ = std::move(new_ordered_options);
+  for (size_t i = 0; i < ordered_options_.size(); i++) {
+    options_[ordered_options_[i].pos]->order = i;
+  }
+}
+
+DcOptions DcOptionsSet::get_dc_options() const {
+  DcOptions result;
+  for (auto id : ordered_options_) {
+    result.dc_options.push_back(options_[id.pos]->option);
+  }
+  return result;
+}
+
+Result<DcOptionsSet::ConnectionInfo> DcOptionsSet::find_connection(DcId dc_id, bool allow_media_only, bool use_static) {
+  std::vector<ConnectionInfo> options;
+  std::vector<ConnectionInfo> static_options;
+
+  for (auto &option_info : options_) {
+    auto &option = option_info->option;
+    if (option.get_dc_id() != dc_id) {
+      continue;
+    }
+    if (!option.is_valid()) {
+      LOG(INFO) << "Skip invalid DC option";
+      continue;
+    }
+    if (!allow_media_only && option.is_media_only()) {
+      LOG(DEBUG) << "Skip media only option";
+      continue;
+    }
+
+    ConnectionInfo info;
+    info.option = &option;
+    info.order = option_info->order;
+
+    OptionStat *option_stat = get_option_stat(option_info.get());
+
+    info.use_http = false;
+    info.stat = &option_stat->tcp_stat;
+    if (option.is_static()) {
+      static_options.push_back(info);
+    } else {
+      options.push_back(info);
+    }
+
+    if (!option.is_obfuscated_tcp_only() && !option.is_static() && false) {  // TODO fix HTTP-mode and enable it
+      info.use_http = true;
+      info.stat = &option_stat->http_stat;
+      options.push_back(info);
+    }
+  }
+
+  if (use_static) {
+    if (!static_options.empty()) {
+      options = std::move(static_options);
+    }
+  } else {
+    if (options.empty()) {
+      options = std::move(static_options);
+    }
+  }
+  bool have_media_only = std::any_of(options.begin(), options.end(), [](auto &v) { return v.option->is_media_only(); });
+  if (have_media_only) {
+    options.erase(std::remove_if(options.begin(), options.end(), [](auto &v) { return !v.option->is_media_only(); }),
+                  options.end());
+  }
+
+  if (options.empty()) {
+    return Status::Error(PSLICE() << "No such connection: " << tag("dc_id", dc_id)
+                                  << tag("allow_media_only", allow_media_only) << tag("use_static", use_static));
+  }
+
+  auto last_error_at = std::min_element(options.begin(), options.end(),
+                                        [](const auto &a_option, const auto &b_option) {
+                                          return a_option.stat->error_at > b_option.stat->error_at;
+                                        })
+                           ->stat->error_at;
+
+  auto result = *std::min_element(options.begin(), options.end(), [](const auto &a_option, const auto &b_option) {
+    auto &a = *a_option.stat;
+    auto &b = *b_option.stat;
+    auto a_state = a.state();
+    auto b_state = b.state();
+    if (a_state != b_state) {
+      return a_state < b_state;
+    }
+    if (a_state == Stat::Ok) {
+      if (a_option.order == b_option.order) {
+        return a_option.use_http < b_option.use_http;
+      }
+      return a_option.order < b_option.order;
+    } else if (a_state == Stat::Error) {
+      return a.error_at < b.error_at;
+    }
+    return a_option.order < b_option.order;
+  });
+  result.should_check = !result.stat->is_ok() || result.use_http || last_error_at > Time::now_cached() - 10;
+  return result;
+}
+
+void DcOptionsSet::reset() {
+  ordered_options_.clear();
+}
+
+DcOptionsSet::DcOptionInfo *DcOptionsSet::register_dc_option(DcOption &&option) {
+  auto info = std::make_unique<DcOptionInfo>(std::move(option), options_.size());
+  init_option_stat(info.get());
+  auto result = info.get();
+  options_.push_back(std::move(info));
+  return result;
+}
+
+void DcOptionsSet::init_option_stat(DcOptionInfo *option_info) {
+  const auto &ip_address = option_info->option.get_ip_address();
+  auto it_ok = option_to_stat_id_.insert(std::make_pair(ip_address, 0));
+  if (it_ok.second) {
+    it_ok.first->second = option_stats_.create(std::make_unique<OptionStat>());
+  }
+  option_info->stat_id = it_ok.first->second;
+}
+
+DcOptionsSet::OptionStat *DcOptionsSet::get_option_stat(const DcOptionInfo *option_info) {
+  return option_stats_.get(option_info->stat_id)->get();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/DcOptionsSet.h b/libs/tdlib/td/td/telegram/net/DcOptionsSet.h
new file mode 100644
index 0000000000..e57e90036e
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/DcOptionsSet.h
@@ -0,0 +1,105 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/net/DcOptions.h"
+
+#include "td/utils/Container.h"
+#include "td/utils/port/IPAddress.h"
+#include "td/utils/Status.h"
+#include "td/utils/Time.h"
+
+#include <map>
+
+namespace td {
+class DcOptionsSet {
+ public:
+  void add_dc_options(DcOptions dc_options);
+
+  DcOptions get_dc_options() const;
+
+  struct Stat {
+    double ok_at{-1000};
+    double error_at{-1001};
+    double check_at{-1002};
+    enum State { Ok, Error, Checking };
+
+    void on_ok() {
+      ok_at = Time::now_cached();
+    }
+    void on_error() {
+      error_at = Time::now_cached();
+    }
+    void on_check() {
+      check_at = Time::now_cached();
+    }
+    bool is_ok() const {
+      return state() == Ok;
+    }
+    State state() const {
+      if (ok_at > error_at && ok_at > check_at) {
+        return Ok;
+      }
+      if (check_at > ok_at && check_at > error_at) {
+        return Checking;
+      }
+      return Error;
+    }
+  };
+
+  struct ConnectionInfo {
+    DcOption *option{nullptr};
+    bool use_http{false};
+    size_t order{0};
+    bool should_check{false};
+    Stat *stat{nullptr};
+  };
+
+  Result<ConnectionInfo> find_connection(DcId dc_id, bool allow_media_only, bool use_static);
+  void reset();
+
+ private:
+  enum class State { Error, Ok, Checking };
+
+  struct OptionStat {
+    Stat tcp_stat;
+    Stat http_stat;
+  };
+
+  struct DcOptionInfo {
+    DcOption option;
+    int64 stat_id;
+    size_t pos;
+    size_t order = 0;
+
+    DcOptionInfo(DcOption &&option, size_t pos) : option(std::move(option)), pos(pos) {
+    }
+  };
+
+  struct DcOptionId {
+    size_t pos;
+    auto as_tie() const {
+      return pos;
+    }
+    bool operator==(const DcOptionId &other) const {
+      return as_tie() == other.as_tie();
+    }
+    bool operator<(const DcOptionId &other) const {
+      return as_tie() < other.as_tie();
+    }
+  };
+
+  std::vector<std::unique_ptr<DcOptionInfo>> options_;
+  std::vector<DcOptionId> ordered_options_;
+  std::map<IPAddress, int64> option_to_stat_id_;
+  Container<std::unique_ptr<OptionStat>> option_stats_;
+
+  DcOptionInfo *register_dc_option(DcOption &&option);
+  void init_option_stat(DcOptionInfo *option_info);
+  OptionStat *get_option_stat(const DcOptionInfo *option_info);
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/MtprotoHeader.cpp b/libs/tdlib/td/td/telegram/net/MtprotoHeader.cpp
new file mode 100644
index 0000000000..3c41e2d1d9
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/MtprotoHeader.cpp
@@ -0,0 +1,55 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/MtprotoHeader.h"
+
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+
+namespace {
+class HeaderStorer {
+ public:
+  HeaderStorer(const MtprotoHeader::Options &options, bool is_anonymous)
+      : options(options), is_anonymous(is_anonymous) {
+  }
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    constexpr int32 LAYER = 76;
+
+    using td::store;
+    // invokeWithLayer#da9b0d0d {X:Type} layer:int query:!X = X;
+    store(static_cast<int32>(0xda9b0d0d), storer);
+    store(LAYER, storer);
+    // initConnection#c7481da6 {X:Type} api_id:int device_model:string system_version:string app_version:string
+    // system_lang_code:string lang_pack:string lang_code:string query:!X = X;
+    store(static_cast<int32>(0xc7481da6), storer);
+    store(options.api_id, storer);
+    if (is_anonymous) {
+      store(Slice("n/a"), storer);
+      store(Slice("n/a"), storer);
+    } else {
+      store(options.device_model, storer);
+      store(options.system_version, storer);
+    }
+    store(options.application_version, storer);
+    store(options.system_language_code, storer);
+    store(string(), storer);
+    store(string(), storer);
+  }
+
+ private:
+  const MtprotoHeader::Options &options;
+  bool is_anonymous;
+};
+}  // namespace
+
+string MtprotoHeader::gen_header(const MtprotoHeader::Options &options, bool is_anonymous) {
+  HeaderStorer storer(options, is_anonymous);
+  return serialize(storer);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/MtprotoHeader.h b/libs/tdlib/td/td/telegram/net/MtprotoHeader.h
new file mode 100644
index 0000000000..e7f4a22bdb
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/MtprotoHeader.h
@@ -0,0 +1,41 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+
+namespace td {
+class MtprotoHeader {
+ public:
+  struct Options {
+    int32 api_id;
+    string system_language_code;
+    string device_model;
+    string system_version;
+    string application_version;
+  };
+
+  explicit MtprotoHeader(const Options &options)
+      : default_header_(gen_header(options, false)), anonymous_header_(gen_header(options, true)) {
+  }
+
+  Slice get_default_header() const {
+    return default_header_;
+  }
+  Slice get_anonymous_header() const {
+    return anonymous_header_;
+  }
+
+ private:
+  string default_header_;
+  string anonymous_header_;
+
+  static string gen_header(const Options &options, bool is_anonymous);
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/NetActor.cpp b/libs/tdlib/td/td/telegram/net/NetActor.cpp
new file mode 100644
index 0000000000..68c14a1a26
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/NetActor.cpp
@@ -0,0 +1,36 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/NetActor.h"
+
+#include "td/telegram/Global.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+#include "td/telegram/Td.h"
+
+namespace td {
+
+NetActor::NetActor() : td(static_cast<Td *>(G()->td().get_actor_unsafe())) {
+}
+
+void NetActor::set_parent(ActorShared<> parent) {
+  parent_ = std::move(parent);
+}
+
+void NetActor::on_result(NetQueryPtr query) {
+  CHECK(query->is_ready());
+  if (query->is_ok()) {
+    on_result(query->id(), query->move_as_ok());
+  } else {
+    on_error(query->id(), query->move_as_error());
+  }
+  on_result_finish();
+}
+
+void NetActor::send_query(NetQueryPtr query) {
+  G()->net_query_dispatcher().dispatch_with_callback(std::move(query), actor_shared(this));
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/NetActor.h b/libs/tdlib/td/td/telegram/net/NetActor.h
new file mode 100644
index 0000000000..71972f6070
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/NetActor.h
@@ -0,0 +1,42 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/actor/actor.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+class Td;
+
+class NetActor : public NetQueryCallback {
+ public:
+  NetActor();
+  void set_parent(ActorShared<> parent);
+  void on_result(NetQueryPtr query) override;
+  virtual void on_result(uint64 id, BufferSlice packet) {
+    UNREACHABLE();
+  }
+  virtual void on_error(uint64 id, Status status) {
+    UNREACHABLE();
+  }
+  virtual void on_result_finish() {
+  }
+
+ protected:
+  ActorShared<> parent_;
+  void send_query(NetQueryPtr query);
+  Td *td;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/NetQuery.cpp b/libs/tdlib/td/td/telegram/net/NetQuery.cpp
new file mode 100644
index 0000000000..8cda0bccab
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/NetQuery.cpp
@@ -0,0 +1,63 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/telegram/Global.h"
+
+namespace td {
+ListNode net_query_list_;
+
+int32 NetQuery::get_my_id() {
+  return G()->get_my_id();
+}
+
+void NetQuery::on_net_write(size_t size) {
+  if (file_type_ == -1) {
+    return;
+  }
+  G()->get_net_stats_file_callbacks().at(file_type_)->on_write(size);
+}
+void NetQuery::on_net_read(size_t size) {
+  if (file_type_ == -1) {
+    return;
+  }
+  G()->get_net_stats_file_callbacks().at(file_type_)->on_read(size);
+}
+int32 NetQuery::tl_magic(const BufferSlice &buffer_slice) {
+  auto slice = buffer_slice.as_slice();
+  if (slice.size() < 4) {
+    return 0;
+  }
+  return as<int32>(slice.begin());
+}
+
+void dump_pending_network_queries() {
+  auto n = NetQueryCounter::get_count();
+  LOG(WARNING) << tag("pending net queries", n);
+
+  decltype(n) i = 0;
+  bool was_gap = false;
+  for (auto end = &net_query_list_, cur = end->prev; cur != end; cur = cur->prev, i++) {
+    if (i < 20 || i + 20 > n || i % (n / 20 + 1) == 0) {
+      if (was_gap) {
+        LOG(WARNING) << "...";
+        was_gap = false;
+      }
+      auto nq = &static_cast<NetQuery &>(*cur);
+      LOG(WARNING) << tag("id", nq->my_id_) << *nq << tag("total_flood", td::format::as_time(nq->total_timeout)) << " "
+                   << tag("since start", td::format::as_time(td::Time::now_cached() - nq->start_timestamp_))
+                   << tag("state", nq->debug_str_)
+                   << tag("since state", td::format::as_time(td::Time::now_cached() - nq->debug_timestamp_))
+                   << tag("resend_cnt", nq->debug_resend_cnt_) << tag("fail_cnt", nq->debug_send_failed_cnt_)
+                   << tag("ack", nq->debug_ack) << tag("unknown", nq->debug_unknown);
+    } else {
+      was_gap = true;
+    }
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/NetQuery.h b/libs/tdlib/td/td/telegram/net/NetQuery.h
new file mode 100644
index 0000000000..ccf1034a65
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/NetQuery.h
@@ -0,0 +1,409 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/net/DcId.h"
+#include "td/telegram/net/NetQueryCounter.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+#include "td/actor/SignalSlot.h"
+
+#include "td/mtproto/utils.h"  // for create_storer, fetch_result TODO
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/List.h"
+#include "td/utils/logging.h"
+#include "td/utils/ObjectPool.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/Time.h"
+
+#include <atomic>
+#include <utility>
+
+namespace td {
+
+class NetQuery;
+using NetQueryPtr = ObjectPool<NetQuery>::OwnerPtr;
+using NetQueryRef = ObjectPool<NetQuery>::WeakPtr;
+
+class NetQueryCallback : public Actor {
+ public:
+  virtual void on_result(NetQueryPtr query);
+  virtual void on_result_resendable(NetQueryPtr query, Promise<NetQueryPtr> promise);
+};
+
+extern ListNode net_query_list_;
+
+class NetQuery : public ListNode {
+ public:
+  NetQuery() = default;
+
+  enum class State : int8 { Empty, Query, OK, Error };
+  enum class Type { Common, Upload, Download, DownloadSmall };
+  enum class AuthFlag : int8 { Off, On };
+  enum class GzipFlag : int8 { Off, On };
+  enum Error : int32 { Resend = 202, Cancelled = 203, ResendInvokeAfter = 204 };
+
+  uint64 id() const {
+    return id_;
+  }
+
+  DcId dc_id() const {
+    return dc_id_;
+  }
+
+  Type type() const {
+    return type_;
+  }
+
+  GzipFlag gzip_flag() const {
+    return gzip_flag_;
+  }
+
+  AuthFlag auth_flag() const {
+    return auth_flag_;
+  }
+
+  int32 tl_constructor() const {
+    return tl_constructor_;
+  }
+
+  void resend(DcId new_dc_id) {
+    VLOG(net_query) << "Resend" << *this;
+    debug_resend_cnt_++;
+    dc_id_ = new_dc_id;
+    status_ = Status::OK();
+    state_ = State::Query;
+  }
+
+  void resend() {
+    resend(dc_id_);
+  }
+
+  BufferSlice &query() {
+    return query_;
+  }
+
+  BufferSlice &ok() {
+    CHECK(state_ == State::OK);
+    return answer_;
+  }
+
+  const BufferSlice &ok() const {
+    CHECK(state_ == State::OK);
+    return answer_;
+  }
+
+  Status &error() {
+    CHECK(state_ == State::Error);
+    return status_;
+  }
+
+  const Status &error() const {
+    CHECK(state_ == State::Error);
+    return status_;
+  }
+
+  BufferSlice move_as_ok() {
+    auto ok = std::move(answer_);
+    clear();
+    return ok;
+  }
+  Status move_as_error() TD_WARN_UNUSED_RESULT {
+    auto status = std::move(status_);
+    clear();
+    return status;
+  }
+
+  void set_ok(BufferSlice slice) {
+    VLOG(net_query) << "Got answer " << *this;
+    CHECK(state_ == State::Query);
+    answer_ = std::move(slice);
+    state_ = State::OK;
+  }
+
+  void on_net_write(size_t size);
+  void on_net_read(size_t size);
+
+  void set_error(Status status, string source = "") {
+    if (status.code() == Error::Resend || status.code() == Error::Cancelled ||
+        status.code() == Error::ResendInvokeAfter) {
+      return set_error_impl(Status::Error(200, PSLICE() << status), std::move(source));
+    }
+    set_error_impl(std::move(status), source);
+  }
+
+  void set_error_resend() {
+    set_error_impl(Status::Error<Error::Resend>());
+  }
+
+  void set_error_cancelled() {
+    set_error_impl(Status::Error<Error::Cancelled>());
+  }
+
+  void set_error_resend_invoke_after() {
+    set_error_impl(Status::Error<Error::ResendInvokeAfter>());
+  }
+
+  bool update_is_ready() {
+    if (state_ == State::Query) {
+      if (cancellation_token_.load(std::memory_order_relaxed) == 0 || cancel_slot_.was_signal()) {
+        set_error_cancelled();
+        return true;
+      }
+      return false;
+    }
+    return true;
+  }
+
+  bool is_ready() const {
+    return state_ != State::Query;
+  }
+
+  bool is_error() const {
+    return state_ == State::Error;
+  }
+
+  bool is_ok() const {
+    return state_ == State::OK;
+  }
+
+  int32 ok_tl_constructor() const {
+    return tl_magic(answer_);
+  }
+
+  void ignore() const {
+    status_.ignore();
+  }
+
+  uint64 session_id() const {
+    return session_id_.load(std::memory_order_relaxed);
+  }
+  void set_session_id(uint64 session_id) {
+    session_id_.store(session_id, std::memory_order_relaxed);
+  }
+
+  uint64 message_id() const {
+    return message_id_;
+  }
+  void set_message_id(uint64 message_id) {
+    message_id_ = message_id;
+  }
+
+  NetQueryRef invoke_after() const {
+    return invoke_after_;
+  }
+  void set_invoke_after(NetQueryRef ref) {
+    invoke_after_ = ref;
+  }
+  void set_session_rand(uint32 session_rand) {
+    session_rand_ = session_rand;
+  }
+  uint32 session_rand() const {
+    return session_rand_;
+  }
+
+  void cancel(int32 cancellation_token) {
+    cancellation_token_.compare_exchange_strong(cancellation_token, 0, std::memory_order_relaxed);
+  }
+  void set_cancellation_token(int32 cancellation_token) {
+    cancellation_token_.store(cancellation_token, std::memory_order_relaxed);
+  }
+
+  void clear() {
+    LOG_IF(ERROR, !is_ready()) << "Destroy not ready query " << *this << " " << tag("debug", debug_str_);
+    // TODO: CHECK if net_query is lost here
+    cancel_slot_.close();
+    *this = NetQuery();
+  }
+  bool empty() const {
+    return state_ == State::Empty || nq_counter_.empty() || may_be_lost_;
+  }
+
+  void stop_track() {
+    nq_counter_ = NetQueryCounter();
+    remove();
+  }
+
+  void debug_send_failed() {
+    debug_send_failed_cnt_++;
+  }
+
+  void debug(string str, bool may_be_lost = false) {
+    may_be_lost_ = may_be_lost;
+    debug_str_ = std::move(str);
+    debug_timestamp_ = Time::now();
+    debug_cnt_++;
+    VLOG(net_query) << *this << " " << tag("debug", debug_str_);
+  }
+  void set_callback(ActorShared<NetQueryCallback> callback) {
+    callback_ = std::move(callback);
+  }
+  ActorShared<NetQueryCallback> move_callback() {
+    return std::move(callback_);
+  }
+
+  void start_migrate(int32 sched_id) {
+    using ::td::start_migrate;
+    start_migrate(cancel_slot_, sched_id);
+  }
+  void finish_migrate() {
+    using ::td::finish_migrate;
+    finish_migrate(cancel_slot_);
+  }
+
+  static int32 tl_magic(const BufferSlice &buffer_slice);
+
+ private:
+  State state_ = State::Empty;
+  Type type_;
+  AuthFlag auth_flag_;
+  GzipFlag gzip_flag_;
+  DcId dc_id_;
+
+  Status status_;
+  uint64 id_;
+  BufferSlice query_;
+  BufferSlice answer_;
+  int32 tl_constructor_;
+
+  NetQueryRef invoke_after_;
+  uint32 session_rand_ = 0;
+  template <class T>
+  struct movable_atomic : public std::atomic<T> {
+    movable_atomic() = default;
+    movable_atomic(T &&x) : std::atomic<T>(std::forward<T>(x)) {
+    }
+    movable_atomic(movable_atomic &&other) {
+      this->store(other.load(std::memory_order_relaxed), std::memory_order_relaxed);
+    }
+    movable_atomic &operator=(movable_atomic &&other) {
+      this->store(other.load(std::memory_order_relaxed), std::memory_order_relaxed);
+      return *this;
+    }
+    movable_atomic(const movable_atomic &other) = delete;
+    movable_atomic &operator=(const movable_atomic &other) = delete;
+    ~movable_atomic() = default;
+  };
+
+  static int32 get_my_id();
+
+  movable_atomic<uint64> session_id_{0};
+  uint64 message_id_;
+
+  movable_atomic<int32> cancellation_token_{-1};  // == 0 if query is canceled
+  ActorShared<NetQueryCallback> callback_;
+
+  void set_error_impl(Status status, string source = "") {
+    VLOG(net_query) << "Got error " << *this << " " << status;
+    status_ = std::move(status);
+    state_ = State::Error;
+    source_ = std::move(source);
+  }
+
+ public:
+  double next_timeout = 1;
+  double total_timeout = 0;
+  double total_timeout_limit = 60;
+  double last_timeout = 0;
+  bool need_resend_on_503 = true;
+  bool may_be_lost_ = false;
+  string debug_str_ = "empty";
+  string source_ = "";
+  double debug_timestamp_;
+  int32 debug_cnt_ = 0;
+  int32 debug_send_failed_cnt_ = 0;
+  int32 debug_resend_cnt_ = 0;
+  int debug_ack = 0;
+  bool debug_unknown = false;
+  int32 dispatch_ttl = -1;
+  Slot cancel_slot_;
+  Promise<> quick_ack_promise_;
+  int32 file_type_ = -1;
+
+  double start_timestamp_;
+  int32 my_id_ = 0;
+  NetQueryCounter nq_counter_;
+
+  NetQuery(State state, uint64 id, BufferSlice &&query, BufferSlice &&answer, DcId dc_id, Type type, AuthFlag auth_flag,
+           GzipFlag gzip_flag, int32 tl_constructor)
+      : state_(state)
+      , type_(type)
+      , auth_flag_(auth_flag)
+      , gzip_flag_(gzip_flag)
+      , dc_id_(dc_id)
+      , status_()
+      , id_(id)
+      , query_(std::move(query))
+      , answer_(std::move(answer))
+      , tl_constructor_(tl_constructor)
+      , nq_counter_(true) {
+    my_id_ = get_my_id();
+    start_timestamp_ = Time::now();
+    LOG(INFO) << *this;
+    // net_query_list_.put(this);
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &stream, const NetQuery &net_query) {
+  stream << "[Query:";
+  stream << tag("id", net_query.id());
+  stream << tag("tl", format::as_hex(net_query.tl_constructor()));
+  if (!net_query.is_ready()) {
+    stream << tag("state", "Query");
+  } else if (net_query.is_error()) {
+    stream << tag("state", "Error");
+    stream << net_query.error();
+  } else if (net_query.is_ok()) {
+    stream << tag("state", "Result");
+    stream << tag("tl", format::as_hex(net_query.ok_tl_constructor()));
+  }
+  stream << "]";
+  return stream;
+}
+inline StringBuilder &operator<<(StringBuilder &stream, const NetQueryPtr &net_query_ptr) {
+  return stream << *net_query_ptr;
+}
+
+void dump_pending_network_queries();
+
+inline void cancel_query(NetQueryRef &ref) {
+  if (ref.empty()) {
+    return;
+  }
+  ref->cancel(ref.generation());
+}
+
+template <class T>
+Result<typename T::ReturnType> fetch_result(NetQueryPtr query) {
+  CHECK(!query.empty());
+  if (query->is_error()) {
+    return query->move_as_error();
+  }
+  auto buffer = query->move_as_ok();
+  return fetch_result<T>(buffer);
+}
+
+inline void NetQueryCallback::on_result(NetQueryPtr query) {
+  on_result_resendable(std::move(query), Auto());
+}
+inline void NetQueryCallback::on_result_resendable(NetQueryPtr query, Promise<NetQueryPtr> promise) {
+  on_result(std::move(query));
+}
+
+inline void start_migrate(NetQueryPtr &net_query, int32 sched_id) {
+  net_query->start_migrate(sched_id);
+}
+inline void finish_migrate(NetQueryPtr &net_query) {
+  net_query->finish_migrate();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/NetQueryCounter.cpp b/libs/tdlib/td/td/telegram/net/NetQueryCounter.cpp
new file mode 100644
index 0000000000..1952e6abd9
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/NetQueryCounter.cpp
@@ -0,0 +1,13 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/NetQueryCounter.h"
+
+namespace td {
+
+std::atomic<uint64> NetQueryCounter::net_query_cnt_{0};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/NetQueryCounter.h b/libs/tdlib/td/td/telegram/net/NetQueryCounter.h
new file mode 100644
index 0000000000..0599d8cf36
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/NetQueryCounter.h
@@ -0,0 +1,55 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+#include <atomic>
+
+namespace td {
+
+class NetQueryCounter {
+  static std::atomic<uint64> net_query_cnt_;
+
+ public:
+  static uint64 get_count() {
+    return net_query_cnt_.load();
+  }
+
+  bool empty() const {
+    return !is_alive_;
+  }
+
+  explicit NetQueryCounter(bool is_alive = false) : is_alive_(is_alive) {
+    if (is_alive) {
+      net_query_cnt_++;
+    }
+  }
+
+  NetQueryCounter(const NetQueryCounter &other) = delete;
+  NetQueryCounter &operator=(const NetQueryCounter &other) = delete;
+  NetQueryCounter(NetQueryCounter &&other) : is_alive_(other.is_alive_) {
+    other.is_alive_ = false;
+  }
+  NetQueryCounter &operator=(NetQueryCounter &&other) {
+    if (is_alive_) {
+      net_query_cnt_--;
+    }
+    is_alive_ = other.is_alive_;
+    other.is_alive_ = false;
+    return *this;
+  }
+  ~NetQueryCounter() {
+    if (is_alive_) {
+      net_query_cnt_--;
+    }
+  }
+
+ private:
+  bool is_alive_;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/NetQueryCreator.cpp b/libs/tdlib/td/td/telegram/net/NetQueryCreator.cpp
new file mode 100644
index 0000000000..20d71d3b98
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/NetQueryCreator.cpp
@@ -0,0 +1,40 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/NetQueryCreator.h"
+
+#include "td/utils/Gzip.h"
+
+namespace td {
+NetQueryCreator::Ptr NetQueryCreator::create(uint64 id, const Storer &storer, DcId dc_id, NetQuery::Type type,
+                                             NetQuery::AuthFlag auth_flag, NetQuery::GzipFlag gzip_flag,
+                                             double total_timeout_limit) {
+  BufferSlice slice(storer.size());
+  storer.store(slice.as_slice().ubegin());
+
+  // TODO: magic constant
+  if (slice.size() < (1 << 8)) {
+    gzip_flag = NetQuery::GzipFlag::Off;
+  }
+  int32 tl_constructor = NetQuery::tl_magic(slice);
+  if (gzip_flag == NetQuery::GzipFlag::On) {
+    // TODO: try to compress files?
+    BufferSlice compressed;
+    compressed = gzencode(slice.as_slice());
+    if (compressed.empty()) {
+      gzip_flag = NetQuery::GzipFlag::Off;
+    } else {
+      slice = std::move(compressed);
+    }
+  }
+
+  auto query = object_pool_.create(NetQuery::State::Query, id, std::move(slice), BufferSlice(), dc_id, type, auth_flag,
+                                   gzip_flag, tl_constructor);
+  query->set_cancellation_token(query.generation());
+  query->total_timeout_limit = total_timeout_limit;
+  return query;
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/NetQueryCreator.h b/libs/tdlib/td/td/telegram/net/NetQueryCreator.h
new file mode 100644
index 0000000000..8973dc46bf
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/NetQueryCreator.h
@@ -0,0 +1,54 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/net/NetQuery.h"
+#include "td/telegram/UniqueId.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/ObjectPool.h"
+#include "td/utils/Storer.h"
+
+namespace td {
+class NetQueryCreator {
+ public:
+  using Ptr = NetQueryPtr;
+  using Ref = NetQueryRef;
+
+  NetQueryCreator() {
+    object_pool_.set_check_empty(true);
+  }
+
+  void stop_check() {
+    object_pool_.set_check_empty(false);
+  }
+
+  Ptr create_result(BufferSlice &&buffer, DcId dc_id = DcId::main(),
+                    NetQuery::AuthFlag auth_flag = NetQuery::AuthFlag::On,
+                    NetQuery::GzipFlag gzip_flag = NetQuery::GzipFlag::Off) {
+    return create_result(0, std::move(buffer), dc_id, auth_flag, gzip_flag);
+  }
+  Ptr create_result(uint64 id, BufferSlice &&buffer, DcId dc_id = DcId::main(),
+                    NetQuery::AuthFlag auth_flag = NetQuery::AuthFlag::On,
+                    NetQuery::GzipFlag gzip_flag = NetQuery::GzipFlag::Off) {
+    return object_pool_.create(NetQuery::State::OK, id, BufferSlice(), std::move(buffer), dc_id, NetQuery::Type::Common,
+                               auth_flag, gzip_flag, 0);
+  }
+
+  Ptr create(const Storer &storer, DcId dc_id = DcId::main(), NetQuery::Type type = NetQuery::Type::Common,
+             NetQuery::AuthFlag auth_flag = NetQuery::AuthFlag::On,
+             NetQuery::GzipFlag gzip_flag = NetQuery::GzipFlag::On, double total_timeout_limit = 60) {
+    return create(UniqueId::next(), storer, dc_id, type, auth_flag, gzip_flag, total_timeout_limit);
+  }
+  Ptr create(uint64 id, const Storer &storer, DcId dc_id = DcId::main(), NetQuery::Type type = NetQuery::Type::Common,
+             NetQuery::AuthFlag auth_flag = NetQuery::AuthFlag::On,
+             NetQuery::GzipFlag gzip_flag = NetQuery::GzipFlag::On, double total_timeout_limit = 60);
+
+ private:
+  ObjectPool<NetQuery> object_pool_;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/NetQueryDelayer.cpp b/libs/tdlib/td/td/telegram/net/NetQueryDelayer.cpp
new file mode 100644
index 0000000000..0950b19f87
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/NetQueryDelayer.cpp
@@ -0,0 +1,119 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/NetQueryDelayer.h"
+
+#include "td/telegram/Global.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+namespace td {
+void NetQueryDelayer::delay(NetQueryPtr query) {
+  query->debug("try delay");
+  query->is_ready();
+  CHECK(query->is_error());
+  auto code = query->error().code();
+  double timeout = 0;
+  if (code < 0 || code == 500) {
+    // skip
+  } else if (code == 420) {
+    auto msg = query->error().message();
+    auto prefix = Slice("FLOOD_WAIT_");
+    if (msg.substr(0, prefix.size()) == prefix) {
+      timeout = to_integer<int>(msg.substr(prefix.size()));
+      if (timeout < 0) {
+        timeout = 0;
+      }
+      if (timeout > 24 * 60 * 60) {
+        timeout = 24 * 60 * 60;
+      }
+    }
+  } else {
+    G()->net_query_dispatcher().dispatch(std::move(query));
+    return;
+  }
+
+  if (timeout == 0) {
+    timeout = query->next_timeout;
+    if (timeout < 60) {
+      query->next_timeout *= 2;
+    }
+  } else {
+    query->next_timeout = 1;
+  }
+  query->total_timeout += timeout;
+  query->last_timeout = timeout;
+
+  auto error = query->error().move_as_error();
+  query->resend();
+
+  // Fix for infinity flood control
+  if (!query->need_resend_on_503 && code == -503) {
+    query->set_error(Status::Error(502, "Bad Gateway"));
+    query->debug("DcManager: send to DcManager");
+    G()->net_query_dispatcher().dispatch(std::move(query));
+    return;
+  }
+
+  if (query->total_timeout > query->total_timeout_limit) {
+    // TODO: support timeouts in DcAuth and GetConfig
+    LOG(WARNING) << "Failed: " << query << " " << tag("timeout", timeout) << tag("total_timeout", query->total_timeout)
+                 << " because of " << error << " from " << query->source_;
+    // NB: code must differ from tdapi FLOOD_WAIT code
+    query->set_error(
+        Status::Error(429, PSLICE() << "Too Many Requests: retry after " << static_cast<int32>(timeout + 0.999)));
+    query->debug("DcManager: send to DcManager");
+    G()->net_query_dispatcher().dispatch(std::move(query));
+    return;
+  }
+
+  LOG(WARNING) << "Delay: " << query << " " << tag("timeout", timeout) << tag("total_timeout", query->total_timeout)
+               << " because of " << error << " from " << query->source_;
+  query->debug(PSTRING() << "delay for " << format::as_time(timeout));
+  auto id = container_.create(QuerySlot());
+  auto *query_slot = container_.get(id);
+  query_slot->query_ = std::move(query);
+  query_slot->timeout_.set_event(EventCreator::yield(actor_shared(this, id)));
+  query_slot->timeout_.set_timeout_in(timeout);
+}
+
+void NetQueryDelayer::wakeup() {
+  auto link_token = get_link_token();
+  if (link_token) {
+    LOG(INFO) << "raw_event";
+    on_slot_event(link_token);
+  }
+  loop();
+}
+
+void NetQueryDelayer::on_slot_event(uint64 id) {
+  auto *slot = container_.get(id);
+  if (slot == nullptr) {
+    return;
+  }
+  auto query = std::move(slot->query_);
+  if (!query->invoke_after().empty()) {
+    // Fail query after timeout expired if it is a part of an invokeAfter chain.
+    // It is not necessary but helps to avoid server problems, when previous query was lost.
+    query->set_error_resend_invoke_after();
+  }
+  slot->timeout_.close();
+  container_.erase(id);
+  G()->net_query_dispatcher().dispatch(std::move(query));
+}
+
+void NetQueryDelayer::tear_down() {
+  container_.for_each([](auto id, auto &query_slot) {
+    query_slot.query_->set_error(Status::Error(500, "Internal Server Error: closing"));
+    G()->net_query_dispatcher().dispatch(std::move(query_slot.query_));
+  });
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/NetQueryDelayer.h b/libs/tdlib/td/td/telegram/net/NetQueryDelayer.h
new file mode 100644
index 0000000000..5083434004
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/NetQueryDelayer.h
@@ -0,0 +1,35 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/SignalSlot.h"
+
+#include "td/utils/Container.h"
+
+namespace td {
+class NetQueryDelayer : public Actor {
+ public:
+  explicit NetQueryDelayer(ActorShared<> parent) : parent_(std::move(parent)) {
+  }
+  void delay(NetQueryPtr query);
+
+ private:
+  struct QuerySlot {
+    NetQueryPtr query_;
+    Slot timeout_;
+  };
+  Container<QuerySlot> container_;
+  ActorShared<> parent_;
+  void wakeup() override;
+
+  void on_slot_event(uint64 id);
+
+  void tear_down() override;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/NetQueryDispatcher.cpp b/libs/tdlib/td/td/telegram/net/NetQueryDispatcher.cpp
new file mode 100644
index 0000000000..9eb0571ace
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/NetQueryDispatcher.cpp
@@ -0,0 +1,295 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/NetQueryDispatcher.h"
+
+#include "td/telegram/net/DcAuthManager.h"
+#include "td/telegram/net/NetQuery.h"
+#include "td/telegram/net/NetQueryDelayer.h"
+#include "td/telegram/net/PublicRsaKeyWatchdog.h"
+#include "td/telegram/net/SessionMultiProxy.h"
+
+#include "td/telegram/ConfigShared.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/Td.h"
+
+#include "td/db/Pmc.h"
+
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/thread.h"
+#include "td/utils/Slice.h"
+
+namespace td {
+void NetQueryDispatcher::dispatch(NetQueryPtr net_query) {
+  net_query->debug("dispatch");
+  if (stop_flag_.load(std::memory_order_relaxed)) {
+    // Set error to avoid warning
+    // No need to send result somewhere, it probably will be ignored anyway
+    net_query->set_error(Status::Error(500, "Internal Server Error: closing"));
+    net_query->clear();
+    net_query.reset();
+    // G()->net_query_creator().release(std::move(net_query));
+    return;
+  }
+
+  if (net_query->is_ready()) {
+    if (net_query->is_error()) {
+      auto code = net_query->error().code();
+      if (code == 303) {
+        try_fix_migrate(net_query);
+      } else if (code == NetQuery::Resend) {
+        net_query->resend();
+      } else if (code < 0 || code == 500 || code == 420) {
+        net_query->debug("sent to NetQueryDelayer");
+        return send_closure(delayer_, &NetQueryDelayer::delay, std::move(net_query));
+      }
+    }
+  }
+
+  if (!net_query->is_ready()) {
+    if (net_query->dispatch_ttl == 0) {
+      net_query->set_error(Status::Error("DispatchTtlError"));
+    }
+  }
+
+  auto dest_dc_id = net_query->dc_id();
+  if (dest_dc_id.is_main()) {
+    dest_dc_id = DcId::internal(main_dc_id_.load(std::memory_order_relaxed));
+  }
+  if (!net_query->is_ready() && wait_dc_init(dest_dc_id, true).is_error()) {
+    net_query->set_error(Status::Error(PSLICE() << "No such dc " << dest_dc_id));
+  }
+
+  if (net_query->is_ready()) {
+    auto callback = net_query->move_callback();
+    if (callback.empty()) {
+      net_query->debug("sent to td (no callback)");
+      send_closure(G()->td(), &NetQueryCallback::on_result, std::move(net_query));
+    } else {
+      net_query->debug("sent to callback", true);
+      send_closure(std::move(callback), &NetQueryCallback::on_result, std::move(net_query));
+    }
+    return;
+  }
+
+  if (net_query->dispatch_ttl > 0) {
+    net_query->dispatch_ttl--;
+  }
+
+  size_t dc_pos = static_cast<size_t>(dest_dc_id.get_raw_id() - 1);
+  CHECK(dc_pos < dcs_.size());
+  switch (net_query->type()) {
+    case NetQuery::Type::Common:
+      net_query->debug(PSTRING() << "sent to main session multi proxy " << dest_dc_id);
+      send_closure_later(dcs_[dc_pos].main_session_, &SessionMultiProxy::send, std::move(net_query));
+      break;
+    case NetQuery::Type::Upload:
+      net_query->debug(PSTRING() << "sent to upload session multi proxy " << dest_dc_id);
+      send_closure_later(dcs_[dc_pos].upload_session_, &SessionMultiProxy::send, std::move(net_query));
+      break;
+    case NetQuery::Type::Download:
+      net_query->debug(PSTRING() << "sent to download session multi proxy " << dest_dc_id);
+      send_closure_later(dcs_[dc_pos].download_session_, &SessionMultiProxy::send, std::move(net_query));
+      break;
+    case NetQuery::Type::DownloadSmall:
+      net_query->debug(PSTRING() << "sent to download small session multi proxy " << dest_dc_id);
+      send_closure_later(dcs_[dc_pos].download_small_session_, &SessionMultiProxy::send, std::move(net_query));
+      break;
+  }
+}
+
+Status NetQueryDispatcher::wait_dc_init(DcId dc_id, bool force) {
+  // TODO: optimize
+  if (!dc_id.is_exact()) {
+    return Status::Error("Not exact DC");
+  }
+  size_t pos = static_cast<size_t>(dc_id.get_raw_id() - 1);
+  if (pos >= dcs_.size()) {
+    return Status::Error("Too big DC id");
+  }
+  auto &dc = dcs_[pos];
+
+  bool should_init = false;
+  if (!dc.is_valid_) {
+    if (!force) {
+      return Status::Error("Invalid DC");
+    }
+    bool expected = false;
+    should_init =
+        dc.is_valid_.compare_exchange_strong(expected, true, std::memory_order_seq_cst, std::memory_order_seq_cst);
+  }
+
+  if (should_init) {
+    std::lock_guard<std::mutex> guard(main_dc_id_mutex_);
+    if (stop_flag_.load(std::memory_order_relaxed)) {
+      return Status::Error("Closing");
+    }
+    // init dc
+    decltype(common_public_rsa_key_) public_rsa_key;
+    bool is_cdn = false;
+    if (dc_id.is_internal()) {
+      public_rsa_key = common_public_rsa_key_;
+    } else {
+      public_rsa_key = std::make_shared<PublicRsaKeyShared>(dc_id);
+      send_closure_later(public_rsa_key_watchdog_, &PublicRsaKeyWatchdog::add_public_rsa_key, public_rsa_key);
+      is_cdn = true;
+    }
+    auto auth_data = AuthDataShared::create(dc_id, std::move(public_rsa_key), td_guard_);
+    int32 session_count = get_session_count();
+    bool use_pfs = get_use_pfs();
+
+    int32 slow_net_scheduler_id = G()->get_slow_net_scheduler_id();
+
+    auto raw_dc_id = dc_id.get_raw_id();
+    dc.main_session_ = create_actor<SessionMultiProxy>(PSLICE() << "SessionMultiProxy:" << raw_dc_id << ":main",
+                                                       session_count, auth_data, raw_dc_id == main_dc_id_,
+                                                       use_pfs || (session_count > 1), false, false, is_cdn);
+    dc.upload_session_ = create_actor_on_scheduler<SessionMultiProxy>(
+        PSLICE() << "SessionMultiProxy:" << raw_dc_id << ":upload", slow_net_scheduler_id,
+        raw_dc_id != 2 && raw_dc_id != 4 ? 8 : 4, auth_data, false, use_pfs || (session_count > 1), false, true,
+        is_cdn);
+    dc.download_session_ = create_actor_on_scheduler<SessionMultiProxy>(
+        PSLICE() << "SessionMultiProxy:" << raw_dc_id << ":download", slow_net_scheduler_id, 1, auth_data, false,
+        use_pfs, true, true, is_cdn);
+    dc.download_small_session_ = create_actor_on_scheduler<SessionMultiProxy>(
+        PSLICE() << "SessionMultiProxy:" << raw_dc_id << ":download_small", slow_net_scheduler_id, 1, auth_data, false,
+        use_pfs, true, true, is_cdn);
+    dc.is_inited_ = true;
+    if (dc_id.is_internal()) {
+      send_closure_later(dc_auth_manager_, &DcAuthManager::add_dc, std::move(auth_data));
+    }
+  } else {
+    while (!dc.is_inited_) {
+      if (stop_flag_.load(std::memory_order_relaxed)) {
+        return Status::Error("Closing");
+      }
+#if !TD_THREAD_UNSUPPORTED
+      td::this_thread::yield();
+#endif
+    }
+  }
+  return Status::OK();
+}
+
+void NetQueryDispatcher::dispatch_with_callback(NetQueryPtr net_query, ActorShared<NetQueryCallback> callback) {
+  net_query->set_callback(std::move(callback));
+  dispatch(std::move(net_query));
+}
+
+void NetQueryDispatcher::stop() {
+  std::lock_guard<std::mutex> guard(main_dc_id_mutex_);
+  td_guard_.reset();
+  stop_flag_ = true;
+  delayer_.hangup();
+  for (const auto &dc : dcs_) {
+    dc.main_session_.hangup();
+    dc.upload_session_.hangup();
+    dc.download_session_.hangup();
+    dc.download_small_session_.hangup();
+  }
+  public_rsa_key_watchdog_.reset();
+  dc_auth_manager_.reset();
+}
+
+void NetQueryDispatcher::update_session_count() {
+  std::lock_guard<std::mutex> guard(main_dc_id_mutex_);
+  int32 session_count = get_session_count();
+  bool use_pfs = get_use_pfs();
+  for (size_t i = 1; i < MAX_DC_COUNT; i++) {
+    if (is_dc_inited(narrow_cast<int32>(i))) {
+      send_closure_later(dcs_[i - 1].main_session_, &SessionMultiProxy::update_options, session_count,
+                         use_pfs || (session_count > 1));
+    }
+  }
+}
+
+void NetQueryDispatcher::update_use_pfs() {
+  std::lock_guard<std::mutex> guard(main_dc_id_mutex_);
+  int32 session_count = get_session_count();
+  bool use_pfs = get_use_pfs();
+  for (size_t i = 1; i < MAX_DC_COUNT; i++) {
+    if (is_dc_inited(narrow_cast<int32>(i))) {
+      send_closure_later(dcs_[i - 1].main_session_, &SessionMultiProxy::update_use_pfs, use_pfs || (session_count > 1));
+      send_closure_later(dcs_[i - 1].upload_session_, &SessionMultiProxy::update_use_pfs, use_pfs);
+      send_closure_later(dcs_[i - 1].download_session_, &SessionMultiProxy::update_use_pfs, use_pfs);
+      send_closure_later(dcs_[i - 1].download_small_session_, &SessionMultiProxy::update_use_pfs, use_pfs);
+    }
+  }
+}
+void NetQueryDispatcher::update_valid_dc(DcId dc_id) {
+  wait_dc_init(dc_id, true);
+}
+
+bool NetQueryDispatcher::is_dc_inited(int32 raw_dc_id) {
+  return dcs_[raw_dc_id - 1].is_valid_.load(std::memory_order_relaxed);
+}
+int32 NetQueryDispatcher::get_session_count() {
+  return max(G()->shared_config().get_option_integer("session_count"), 1);
+}
+
+bool NetQueryDispatcher::get_use_pfs() {
+  return G()->shared_config().get_option_boolean("use_pfs");
+}
+
+NetQueryDispatcher::NetQueryDispatcher(std::function<ActorShared<>()> create_reference) {
+  auto s_main_dc_id = G()->td_db()->get_binlog_pmc()->get("main_dc_id");
+  if (!s_main_dc_id.empty()) {
+    main_dc_id_ = to_integer<int32>(s_main_dc_id);
+  }
+  LOG(INFO) << tag("main_dc_id", main_dc_id_.load(std::memory_order_relaxed));
+  delayer_ = create_actor<NetQueryDelayer>("NetQueryDelayer", create_reference());
+  dc_auth_manager_ = create_actor<DcAuthManager>("DcAuthManager", create_reference());
+  common_public_rsa_key_ = std::make_shared<PublicRsaKeyShared>(DcId::empty());
+  public_rsa_key_watchdog_ = create_actor<PublicRsaKeyWatchdog>("PublicRsaKeyWatchdog", create_reference());
+
+  td_guard_ = create_shared_lambda_guard([actor = create_reference] {});
+}
+
+NetQueryDispatcher::NetQueryDispatcher() = default;
+NetQueryDispatcher::~NetQueryDispatcher() = default;
+
+void NetQueryDispatcher::try_fix_migrate(NetQueryPtr &net_query) {
+  auto msg = net_query->error().message();
+  static constexpr CSlice prefixes[] = {"PHONE_MIGRATE_", "NETWORK_MIGRATE_", "USER_MIGRATE_"};
+  for (auto &prefix : prefixes) {
+    if (msg.substr(0, prefix.size()) == prefix) {
+      int32 new_main_dc_id = to_integer<int32>(msg.substr(prefix.size()));
+      if (!DcId::is_valid(new_main_dc_id)) {
+        LOG(FATAL) << "Receive " << prefix << " to wrong dc " << new_main_dc_id;
+      }
+      if (new_main_dc_id != main_dc_id_.load(std::memory_order_relaxed)) {
+        // Very rare event. Mutex is ok.
+        std::lock_guard<std::mutex> guard(main_dc_id_mutex_);
+        if (new_main_dc_id != main_dc_id_) {
+          LOG(INFO) << "Update: " << tag("main_dc_id", main_dc_id_.load(std::memory_order_relaxed));
+          if (is_dc_inited(main_dc_id_.load(std::memory_order_relaxed))) {
+            send_closure_later(dcs_[main_dc_id_ - 1].main_session_, &SessionMultiProxy::update_main_flag, false);
+          }
+          main_dc_id_ = new_main_dc_id;
+          if (is_dc_inited(main_dc_id_.load(std::memory_order_relaxed))) {
+            send_closure_later(dcs_[main_dc_id_ - 1].main_session_, &SessionMultiProxy::update_main_flag, true);
+          }
+          send_closure_later(dc_auth_manager_, &DcAuthManager::update_main_dc,
+                             DcId::internal(main_dc_id_.load(std::memory_order_relaxed)));
+          G()->td_db()->get_binlog_pmc()->set("main_dc_id", to_string(main_dc_id_.load(std::memory_order_relaxed)));
+        }
+      }
+
+      if (!net_query->dc_id().is_main()) {
+        LOG(ERROR) << msg << " from query to non-main dc " << net_query->dc_id();
+        net_query->resend(DcId::internal(new_main_dc_id));
+      } else {
+        net_query->resend();
+      }
+      break;
+    }
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/NetQueryDispatcher.h b/libs/tdlib/td/td/telegram/net/NetQueryDispatcher.h
new file mode 100644
index 0000000000..461c8b5ba8
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/NetQueryDispatcher.h
@@ -0,0 +1,88 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/telegram/net/AuthDataShared.h"
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/actor/actor.h"
+
+#include "td/utils/common.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Status.h"
+
+#include <array>
+#include <atomic>
+#include <functional>
+#include <memory>
+#include <mutex>
+
+namespace td {
+class NetQueryDelayer;
+class DataCenter;
+class DcAuthManager;
+class SessionMultiProxy;
+class PublicRsaKeyShared;
+class PublicRsaKeyWatchdog;
+}  // namespace td
+
+namespace td {
+// Not just dispatcher.
+class NetQueryDispatcher {
+ public:
+  explicit NetQueryDispatcher(std::function<ActorShared<>()> create_reference);
+  NetQueryDispatcher();
+  NetQueryDispatcher(const NetQueryDispatcher &) = delete;
+  NetQueryDispatcher &operator=(const NetQueryDispatcher &) = delete;
+  NetQueryDispatcher(NetQueryDispatcher &&) = delete;
+  NetQueryDispatcher &operator=(NetQueryDispatcher &&) = delete;
+  ~NetQueryDispatcher();
+
+  void dispatch(NetQueryPtr net_query);
+  void dispatch_with_callback(NetQueryPtr net_query, ActorShared<NetQueryCallback> callback);
+  void stop();
+
+  void update_session_count();
+  void update_use_pfs();
+  void update_valid_dc(DcId dc_id);
+  DcId main_dc_id() {
+    return DcId::internal(main_dc_id_.load());
+  }
+
+ private:
+  std::atomic<bool> stop_flag_{false};
+  ActorOwn<NetQueryDelayer> delayer_;
+  ActorOwn<DcAuthManager> dc_auth_manager_;
+  struct Dc {
+    std::atomic<bool> is_valid_{false};
+    std::atomic<bool> is_inited_{false};  // TODO: cache in scheduler local storage :D
+
+    ActorOwn<SessionMultiProxy> main_session_;
+    ActorOwn<SessionMultiProxy> download_session_;
+    ActorOwn<SessionMultiProxy> download_small_session_;
+    ActorOwn<SessionMultiProxy> upload_session_;
+  };
+  static constexpr size_t MAX_DC_COUNT = 1000;
+  std::array<Dc, MAX_DC_COUNT> dcs_;
+#if TD_EMSCRIPTEN  // FIXME
+  std::atomic<int32> main_dc_id_{2};
+#else
+  std::atomic<int32> main_dc_id_{1};
+#endif
+  std::shared_ptr<PublicRsaKeyShared> common_public_rsa_key_;
+  ActorOwn<PublicRsaKeyWatchdog> public_rsa_key_watchdog_;
+  std::mutex main_dc_id_mutex_;
+  std::shared_ptr<Guard> td_guard_;
+
+  Status wait_dc_init(DcId dc_id, bool force);
+  bool is_dc_inited(int32 raw_dc_id);
+
+  static int32 get_session_count();
+  static bool get_use_pfs();
+
+  void try_fix_migrate(NetQueryPtr &net_query);
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/NetStatsManager.cpp b/libs/tdlib/td/td/telegram/net/NetStatsManager.cpp
new file mode 100644
index 0000000000..ff080db611
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/NetStatsManager.cpp
@@ -0,0 +1,316 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/NetStatsManager.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/Global.h"
+#include "td/telegram/logevent/LogEvent.h"
+#include "td/telegram/StateManager.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/tl_helpers.h"
+
+namespace td {
+
+template <class T>
+static void store(const NetStatsData &net_stats, T &storer) {
+  using ::td::store;
+  store(net_stats.read_size, storer);
+  store(net_stats.write_size, storer);
+  store(net_stats.count, storer);
+  store(net_stats.duration, storer);
+}
+
+template <class T>
+static void parse(NetStatsData &net_stats, T &parser) {
+  using ::td::parse;
+  parse(net_stats.read_size, parser);
+  parse(net_stats.write_size, parser);
+
+  if (parser.version() >= static_cast<int32>(Version::NetStatsCountDuration)) {
+    parse(net_stats.count, parser);
+    parse(net_stats.duration, parser);
+  }
+}
+
+void NetStatsManager::init() {
+  CHECK(!empty());
+  class NetStatsInternalCallback : public NetStats::Callback {
+   public:
+    NetStatsInternalCallback(ActorId<NetStatsManager> parent, size_t id) : parent_(std::move(parent)), id_(id) {
+    }
+
+   private:
+    ActorId<NetStatsManager> parent_;
+    size_t id_;
+    void on_stats_updated() override {
+      send_closure(parent_, &NetStatsManager::on_stats_updated, id_);
+    }
+  };
+
+  for_each_stat([&](NetStatsInfo &stat, size_t id, CSlice name, FileType) {
+    stat.key = "net_stats_" + name.str();
+    stat.stats.set_callback(std::make_unique<NetStatsInternalCallback>(actor_id(this), id));
+  });
+}
+
+void NetStatsManager::get_network_stats(bool current, Promise<NetworkStats> promise) {
+  NetworkStats result;
+
+  result.since = current ? since_current_ : since_total_;
+
+  for_each_stat([&](NetStatsInfo &info, size_t id, CSlice name, FileType file_type) { update(info, false); });
+
+  for (size_t net_type_i = 0; net_type_i < net_type_size(); net_type_i++) {
+    auto net_type = NetType(net_type_i);
+    NetStatsData total;
+    NetStatsData total_files;
+
+    for_each_stat([&](NetStatsInfo &info, size_t id, CSlice name, FileType file_type) {
+      auto type_stats = info.stats_by_type[net_type_i];
+      auto stats = current ? type_stats.mem_stats : type_stats.mem_stats + type_stats.db_stats;
+      if (id == 0) {
+      } else if (id == 1) {
+        total = stats;
+      } else if (id == call_net_stats_id_) {
+      } else if (file_type != FileType::None) {
+        total_files = total_files + stats;
+      }
+    });
+
+    NetStatsData check;
+    for_each_stat([&](NetStatsInfo &info, size_t id, CSlice name, FileType file_type) {
+      if (id == 1) {
+        return;
+      }
+      auto type_stats = info.stats_by_type[net_type_i];
+      auto stats = current ? type_stats.mem_stats : type_stats.mem_stats + type_stats.db_stats;
+
+      NetworkStatsEntry entry;
+      entry.file_type = file_type;
+      entry.net_type = net_type;
+      entry.rx = stats.read_size;
+      entry.tx = stats.write_size;
+      entry.count = stats.count;
+      entry.duration = stats.duration;
+      if (id == 0) {
+        result.entries.push_back(std::move(entry));
+      } else if (id == call_net_stats_id_) {
+        entry.is_call = true;
+        result.entries.push_back(std::move(entry));
+      } else if (file_type != FileType::None) {
+        if (total_files.read_size != 0) {
+          entry.rx = static_cast<int64>(static_cast<double>(total.read_size) *
+                                        (static_cast<double>(entry.rx) / static_cast<double>(total_files.read_size)));
+        } else {
+          // entry.rx += total.read_size / file_type_size;
+        }
+
+        if (total_files.write_size != 0) {
+          entry.tx = static_cast<int64>(static_cast<double>(total.write_size) *
+                                        (static_cast<double>(entry.tx) / static_cast<double>(total_files.write_size)));
+        } else {
+          // entry.tx += total.write_size / file_type_size;
+        }
+        check.read_size += entry.rx;
+        check.write_size += entry.tx;
+        result.entries.push_back(std::move(entry));
+      }
+    });
+    // LOG(ERROR) << total.read_size << " " << check.read_size;
+    // LOG(ERROR) << total.write_size << " " << check.write_size;
+  }
+
+  promise.set_value(std::move(result));
+}
+
+void NetStatsManager::reset_network_stats() {
+  auto do_reset_network_stats = [&](auto &info) {
+    info.last_sync_stats = info.stats.get_stats();
+    for (size_t net_type_i = 0; net_type_i < net_type_size(); net_type_i++) {
+      auto net_type = NetType(net_type_i);
+      info.stats_by_type[net_type_i] = NetStatsInfo::TypeStats{};
+      auto key = PSTRING() << info.key << "#" << net_type_string(net_type);
+      G()->td_db()->get_binlog_pmc()->erase(key);
+    }
+  };
+
+  for_each_stat([&](NetStatsInfo &info, size_t id, CSlice name, FileType) { do_reset_network_stats(info); });
+
+  auto unix_time = G()->unix_time();
+  since_total_ = unix_time;
+  since_current_ = unix_time;
+  G()->td_db()->get_binlog_pmc()->set("net_stats_since", to_string(unix_time));
+}
+
+void NetStatsManager::add_network_stats(const NetworkStatsEntry &entry) {
+  if (entry.is_call) {
+    return add_network_stats_impl(call_net_stats_, entry);
+  }
+  if (entry.file_type == FileType::None) {
+    return add_network_stats_impl(common_net_stats_, entry);
+  }
+  add_network_stats_impl(media_net_stats_, entry);
+  size_t file_type_n = static_cast<size_t>(entry.file_type);
+  CHECK(file_type_n < file_type_size);
+  add_network_stats_impl(files_stats_[file_type_n], entry);
+}
+
+void NetStatsManager::add_network_stats_impl(NetStatsInfo &info, const NetworkStatsEntry &entry) {
+  auto net_type_i = static_cast<size_t>(entry.net_type);
+  auto &data = info.stats_by_type[net_type_i].mem_stats;
+
+  if (data.read_size + entry.rx < data.read_size || data.write_size + entry.tx < data.write_size ||
+      data.count + entry.count < data.count) {
+    LOG(ERROR) << "Network stats overflow";
+    return;
+  }
+
+  data.read_size += entry.rx;
+  data.write_size += entry.tx;
+  data.count += entry.count;
+  data.duration += entry.duration;
+  save_stats(info, entry.net_type);
+}
+
+void NetStatsManager::start_up() {
+  for_each_stat([&](NetStatsInfo &info, size_t id, CSlice name, FileType) {
+    for (size_t net_type_i = 0; net_type_i < net_type_size(); net_type_i++) {
+      auto net_type = NetType(net_type_i);
+      auto key = PSTRING() << info.key << "#" << net_type_string(net_type);
+
+      auto value = G()->td_db()->get_binlog_pmc()->get(key);
+      if (value.empty()) {
+        continue;
+      }
+      log_event_parse(info.stats_by_type[net_type_i].db_stats, value).ensure();
+    }
+  });
+  auto unix_time = G()->unix_time();
+  since_total_ = 0;
+  since_current_ = unix_time;
+  auto since_str = G()->td_db()->get_binlog_pmc()->get("net_stats_since");
+  if (!since_str.empty()) {
+    auto since = to_integer<int32>(since_str);
+    if (unix_time < since) {
+      since_total_ = unix_time;
+      G()->td_db()->get_binlog_pmc()->set("net_stats_since", to_string(since_total_));
+    } else {
+      since_total_ = since;
+    }
+  } else {
+    // approximate since_total by first run date for new users
+    since_total_ = unix_time;
+    G()->td_db()->get_binlog_pmc()->set("net_stats_since", to_string(since_total_));
+  }
+
+  class NetCallback : public StateManager::Callback {
+   public:
+    explicit NetCallback(ActorId<NetStatsManager> net_stats_manager)
+        : net_stats_manager_(std::move(net_stats_manager)) {
+    }
+    bool on_network(NetType network_type, uint32 network_generation) override {
+      send_closure(net_stats_manager_, &NetStatsManager::on_net_type_updated, network_type);
+      return net_stats_manager_.is_alive();
+    }
+
+   private:
+    ActorId<NetStatsManager> net_stats_manager_;
+  };
+  send_closure(G()->state_manager(), &StateManager::add_callback, make_unique<NetCallback>(actor_id(this)));
+}
+
+std::shared_ptr<NetStatsCallback> NetStatsManager::get_common_stats_callback() const {
+  return common_net_stats_.stats.get_callback();
+}
+
+std::shared_ptr<NetStatsCallback> NetStatsManager::get_media_stats_callback() const {
+  return media_net_stats_.stats.get_callback();
+}
+
+std::vector<std::shared_ptr<NetStatsCallback>> NetStatsManager::get_file_stats_callbacks() const {
+  return transform(files_stats_, [](auto &stat) { return stat.stats.get_callback(); });
+}
+
+void NetStatsManager::update(NetStatsInfo &info, bool force_save) {
+  if (info.net_type == NetType::None) {
+    return;
+  }
+  auto current_stats = info.stats.get_stats();
+  auto diff = current_stats - info.last_sync_stats;
+
+  auto net_type_i = static_cast<size_t>(info.net_type);
+  auto &type_stats = info.stats_by_type[net_type_i];
+
+  info.last_sync_stats = current_stats;
+
+  auto mem_stats = type_stats.mem_stats + diff;
+  type_stats.mem_stats = mem_stats;
+  type_stats.dirty_size += diff.read_size + diff.write_size;
+
+  if (type_stats.dirty_size < 1000 && !force_save) {
+    return;
+  }
+
+  type_stats.dirty_size = 0;
+
+  save_stats(info, info.net_type);
+}
+
+void NetStatsManager::save_stats(NetStatsInfo &info, NetType net_type) {
+  auto net_type_i = static_cast<size_t>(net_type);
+  auto &type_stats = info.stats_by_type[net_type_i];
+
+  auto key = PSTRING() << info.key << "#" << net_type_string(info.net_type);
+  auto stats = type_stats.mem_stats + type_stats.db_stats;
+  // LOG(ERROR) << "SAVE " << key << " " << stats;
+
+  G()->td_db()->get_binlog_pmc()->set(key, log_event_store(stats).as_slice().str());
+}
+
+void NetStatsManager::info_loop(NetStatsInfo &info) {
+  if (info.net_type == NetType::None) {
+    return;
+  }
+  auto mem_stats = info.stats.get_stats();
+  auto diff = mem_stats - info.last_sync_stats;
+  auto size = diff.read_size + diff.write_size;
+  if (size < 1000) {
+    return;
+  }
+  update(info, false);
+}
+
+void NetStatsManager::on_stats_updated(size_t id) {
+  for_each_stat([&](NetStatsInfo &stat, size_t stat_id, CSlice name, FileType) {
+    if (stat_id == id) {
+      info_loop(stat);
+    }
+  });
+}
+
+void NetStatsManager::on_net_type_updated(NetType net_type) {
+  if (net_type == NetType::Unknown) {
+    net_type = NetType::None;
+  }
+  auto do_on_net_type_updated = [&](NetStatsInfo &info) {  // g++ 4.9-6.2 crashes if (auto &info) is used
+    if (info.net_type == net_type) {
+      return;
+    }
+    if (info.net_type != NetType::None) {
+      update(info, true);
+    }
+    info.net_type = net_type;
+  };
+
+  for_each_stat([&](NetStatsInfo &stat, size_t stat_id, CSlice name, FileType) { do_on_net_type_updated(stat); });
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/NetStatsManager.h b/libs/tdlib/td/td/telegram/net/NetStatsManager.h
new file mode 100644
index 0000000000..e363f181cd
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/NetStatsManager.h
@@ -0,0 +1,206 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/td_api.h"
+
+#include "td/telegram/files/FileLocation.h"
+#include "td/telegram/net/NetType.h"
+
+#include "td/net/NetStats.h"
+
+#include "td/utils/Slice.h"
+
+#include <array>
+#include <memory>
+
+namespace td {
+
+struct NetworkStatsEntry {
+  FileType file_type{FileType::None};
+
+  NetType net_type{NetType::Other};
+  int64 rx{0};
+  int64 tx{0};
+
+  bool is_call{false};
+  int64 count{0};
+  double duration{0};
+
+  tl_object_ptr<td_api::NetworkStatisticsEntry> as_td_api() const {
+    if (is_call) {
+      return make_tl_object<td_api::networkStatisticsEntryCall>(::td::as_td_api(net_type), tx, rx, duration);
+    } else {
+      return make_tl_object<td_api::networkStatisticsEntryFile>(::td::as_td_api(file_type), ::td::as_td_api(net_type),
+                                                                tx, rx);
+    }
+  }
+};
+
+struct NetworkStats {
+  int32 since = 0;
+  std::vector<NetworkStatsEntry> entries;
+
+  auto as_td_api() const {
+    auto result = make_tl_object<td_api::networkStatistics>();
+    result->since_date_ = since;
+    result->entries_.reserve(entries.size());
+    for (const auto &entry : entries) {
+      if (entry.rx != 0 || entry.tx != 0) {
+        result->entries_.push_back(entry.as_td_api());
+      }
+    }
+    return result;
+  }
+};
+
+class NetStatsManager : public Actor {
+ public:
+  explicit NetStatsManager(ActorShared<> parent) : parent_(std::move(parent)) {
+  }
+  // Call init just after actor is registered and before getting callbacks
+  void init();
+  std::shared_ptr<NetStatsCallback> get_common_stats_callback() const;
+  std::shared_ptr<NetStatsCallback> get_media_stats_callback() const;
+  std::vector<std::shared_ptr<NetStatsCallback>> get_file_stats_callbacks() const;
+
+  void get_network_stats(bool current, Promise<NetworkStats> promise);
+
+  void reset_network_stats();
+
+  void add_network_stats(const NetworkStatsEntry &entry);
+
+ private:
+  ActorShared<> parent_;
+
+  static constexpr size_t net_type_size() {
+    return static_cast<size_t>(NetType::Size);
+  }
+  // TODO constexpr
+  static CSlice net_type_string(NetType type) {
+    switch (type) {
+      case NetType::Other:
+        return CSlice("other");
+      case NetType::Wifi:
+        return CSlice("wifi");
+      case NetType::Mobile:
+        return CSlice("mobile");
+      case NetType::MobileRoaming:
+        return CSlice("mobile_roaming");
+      default:
+        return CSlice("bug");
+    }
+  }
+
+  struct NetStatsInfo {
+    string key;
+    NetStats stats;
+    NetStatsData last_sync_stats;
+    NetType net_type = NetType::None;
+
+    struct TypeStats {
+      uint64 dirty_size = 0;
+      NetStatsData mem_stats;
+      NetStatsData db_stats;
+    };
+    std::array<TypeStats, 5 /*NetStatsManager::net_type_size()*/> stats_by_type;
+  };
+
+  int32 since_total_{0};
+  int32 since_current_{0};
+  NetStatsInfo common_net_stats_;
+  NetStatsInfo media_net_stats_;
+  std::array<NetStatsInfo, file_type_size> files_stats_;
+  NetStatsInfo call_net_stats_;
+  static constexpr int32 call_net_stats_id_{file_type_size + 2};
+
+  template <class F>
+  void for_each_stat(F &&f) {
+    f(common_net_stats_, 0, CSlice("common"), FileType::None);
+    f(media_net_stats_, 1, CSlice("media"), FileType::None);
+    for (size_t file_type_i = 0; file_type_i < file_type_size; file_type_i++) {
+      auto &stat = files_stats_[file_type_i];
+      f(stat, file_type_i + 2, CSlice(file_type_name[file_type_i]), FileType(file_type_i));
+    }
+    f(call_net_stats_, call_net_stats_id_, CSlice("calls"), FileType::None);
+  }
+
+  void add_network_stats_impl(NetStatsInfo &info, const NetworkStatsEntry &entry);
+
+  void start_up() override;
+  void update(NetStatsInfo &info, bool force_save);
+  void save_stats(NetStatsInfo &info, NetType net_type);
+  void info_loop(NetStatsInfo &info);
+
+  void on_stats_updated(size_t id);
+  void on_net_type_updated(NetType net_type);
+};
+}  // namespace td
+
+/*
+
+networkTypeBluetooth = NetworkType; ?
+networkTypeEthernet = NetworkType;  ?
+
+Android NetType.
+TYPE_BLUETOOTH The Bluetooth data connection.
+TYPE_DUMMY Dummy data connection.
+TYPE_ETHERNET The Ethernet data connection.
+TYPE_MOBILE The Mobile data connection.
+TYPE_MOBILE_DUN A DUN-specific Mobile data connection.
+TYPE_VPN A virtual network using one or more native bearers.
+TYPE_WIFI The WIFI data connection.
+TYPE_WIMAX The WiMAX data connection.
+
+ios NetType
+ReachableViaWiFi,
+ReachableViaWWAN
+
+
+Mobile subtype
+2G
+NETWORK_TYPE_IDEN  ~25 kbps
+NETWORK_TYPE_CDMA  ~ 14-64 kbps
+CTRadioAccessTechnologyCDMA1x
+NETWORK_TYPE_1xRTT  ~ 50-100 kbps
+NETWORK_TYPE_GPRS  ~ 100 kbps
+CTRadioAccessTechnologyEdge
+NETWORK_TYPE_EDGE  ~ 50-100 kbps
+CTRadioAccessTechnologyGPRS
+
+3G
+NETWORK_TYPE_EVDO_0  ~ 400-1000 kbps
+CTRadioAccessTechnologyCDMAEVDORev0
+NETWORK_TYPE_EVDO_A  ~ 600-1400 kbps
+CTRadioAccessTechnologyCDMAEVDORevA
+NETWORK_TYPE_HSPA  ~ 700-1700 kbps
+NETWORK_TYPE_UMTS  ~ 400-7000 kbps
+NETWORK_TYPE_EHRPD  ~ 1-2 Mbps
+NETWORK_TYPE_EVDO_B  ~ 5 Mbps
+CTRadioAccessTechnologyCDMAEVDORevB
+NETWORK_TYPE_HSDPA  ~ 2-14 Mbps
+CTRadioAccessTechnologyHSDPA
+NETWORK_TYPE_HSPAP  ~ 10-20 Mbps
+NETWORK_TYPE_HSUPA  ~ 1-23 Mbps
+CTRadioAccessTechnologyHSUPA
+
+CTRadioAccessTechnologyWCDMA
+CTRadioAccessTechnologyeHRPD
+
+4G
+NETWORK_TYPE_LTE  ~ 10+ Mbps
+CTRadioAccessTechnologyLTE
+
+NETWORK_TYPE_GSM
+NETWORK_TYPE_IWLAN
+NETWORK_TYPE_TD_SCDMA
+NETWORK_TYPE_UNKNOWN
+
+*/
diff --git a/libs/tdlib/td/td/telegram/net/NetType.h b/libs/tdlib/td/td/telegram/net/NetType.h
new file mode 100644
index 0000000000..e04eb1a98c
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/NetType.h
@@ -0,0 +1,52 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/td_api.h"
+
+#include "td/utils/logging.h"
+
+namespace td {
+enum class NetType : int8 { Other, Wifi, Mobile, MobileRoaming, Size, None, Unknown };
+
+inline NetType from_td_api(tl_object_ptr<td_api::NetworkType> &net_type) {
+  if (net_type == nullptr) {
+    return NetType::Other;
+  }
+
+  switch (net_type->get_id()) {
+    case td_api::networkTypeOther::ID:
+      return NetType::Other;
+    case td_api::networkTypeWiFi::ID:
+      return NetType::Wifi;
+    case td_api::networkTypeMobile::ID:
+      return NetType::Mobile;
+    case td_api::networkTypeMobileRoaming::ID:
+      return NetType::MobileRoaming;
+    case td_api::networkTypeNone::ID:
+      return NetType::None;
+    default:
+      UNREACHABLE();
+  }
+}
+
+inline tl_object_ptr<td_api::NetworkType> as_td_api(NetType net_type) {
+  switch (net_type) {
+    case NetType::Other:
+      return make_tl_object<td_api::networkTypeOther>();
+    case NetType::Wifi:
+      return make_tl_object<td_api::networkTypeWiFi>();
+    case NetType::Mobile:
+      return make_tl_object<td_api::networkTypeMobile>();
+    case NetType::MobileRoaming:
+      return make_tl_object<td_api::networkTypeMobileRoaming>();
+    default:
+      UNREACHABLE();
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/PublicRsaKeyShared.cpp b/libs/tdlib/td/td/telegram/net/PublicRsaKeyShared.cpp
new file mode 100644
index 0000000000..44169c66dc
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/PublicRsaKeyShared.cpp
@@ -0,0 +1,145 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/PublicRsaKeyShared.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <algorithm>
+
+namespace td {
+
+PublicRsaKeyShared::PublicRsaKeyShared(DcId dc_id) : dc_id_(dc_id) {
+  if (!dc_id_.is_empty()) {
+    return;
+  }
+  auto add_pem = [this](CSlice pem) {
+    auto r_rsa = RSA::from_pem(pem);
+    CHECK(r_rsa.is_ok()) << r_rsa.error();
+
+    if (r_rsa.is_ok()) {
+      this->add_rsa(r_rsa.move_as_ok());
+    }
+  };
+  //old_key
+  add_pem(
+      "-----BEGIN RSA PUBLIC KEY-----\n"
+      "MIIBCgKCAQEAwVACPi9w23mF3tBkdZz+zwrzKOaaQdr01vAbU4E1pvkfj4sqDsm6\n"
+      "lyDONS789sVoD/xCS9Y0hkkC3gtL1tSfTlgCMOOul9lcixlEKzwKENj1Yz/s7daS\n"
+      "an9tqw3bfUV/nqgbhGX81v/+7RFAEd+RwFnK7a+XYl9sluzHRyVVaTTveB2GazTw\n"
+      "Efzk2DWgkBluml8OREmvfraX3bkHZJTKX4EQSjBbbdJ2ZXIsRrYOXfaA+xayEGB+\n"
+      "8hdlLmAjbCVfaigxX0CDqWeR1yFL9kwd9P0NsZRPsmoqVwMbMu7mStFai6aIhc3n\n"
+      "Slv8kg9qv1m6XHVQY3PnEw+QQtqSIXklHwIDAQAB\n"
+      "-----END RSA PUBLIC KEY-----");
+
+  // a35e0b92d00f9b61c351ce30526cb855649b12a35e01fe39b5b315e81b515779  key1.pub
+  add_pem(
+      "-----BEGIN RSA PUBLIC KEY-----\n"
+      "MIIBCgKCAQEAruw2yP/BCcsJliRoW5eB\n"
+      "VBVle9dtjJw+OYED160Wybum9SXtBBLXriwt4rROd9csv0t0OHCaTmRqBcQ0J8fx\n"
+      "hN6/cpR1GWgOZRUAiQxoMnlt0R93LCX/j1dnVa/gVbCjdSxpbrfY2g2L4frzjJvd\n"
+      "l84Kd9ORYjDEAyFnEA7dD556OptgLQQ2e2iVNq8NZLYTzLp5YpOdO1doK+ttrltg\n"
+      "gTCy5SrKeLoCPPbOgGsdxJxyz5KKcZnSLj16yE5HvJQn0CNpRdENvRUXe6tBP78O\n"
+      "39oJ8BTHp9oIjd6XWXAsp2CvK45Ol8wFXGF710w9lwCGNbmNxNYhtIkdqfsEcwR5\n"
+      "JwIDAQAB\n"
+      "-----END RSA PUBLIC KEY-----\n");
+
+  // f1c346bd6de0c3365658e0740de42372e51262099d47ee097c3ff1e238ebf985  key2.pub
+  add_pem(
+      "-----BEGIN RSA PUBLIC KEY-----\n"
+      "MIIBCgKCAQEAvfLHfYH2r9R70w8prHbl\n"
+      "Wt/nDkh+XkgpflqQVcnAfSuTtO05lNPspQmL8Y2XjVT4t8cT6xAkdgfmmvnvRPOO\n"
+      "KPi0OfJXoRVylFzAQG/j83u5K3kRLbae7fLccVhKZhY46lvsueI1hQdLgNV9n1cQ\n"
+      "3TDS2pQOCtovG4eDl9wacrXOJTG2990VjgnIKNA0UMoP+KF03qzryqIt3oTvZq03\n"
+      "DyWdGK+AZjgBLaDKSnC6qD2cFY81UryRWOab8zKkWAnhw2kFpcqhI0jdV5QaSCEx\n"
+      "vnsjVaX0Y1N0870931/5Jb9ICe4nweZ9kSDF/gip3kWLG0o8XQpChDfyvsqB9OLV\n"
+      "/wIDAQAB\n"
+      "-----END RSA PUBLIC KEY-----\n");
+
+  // 129e129a464a2b515f579fd568f5579e8a6ea2832a362b07f282a7c271acfead  key3.pub
+  add_pem(
+      "-----BEGIN RSA PUBLIC KEY-----\n"
+      "MIIBCgKCAQEAs/ditzm+mPND6xkhzwFI\n"
+      "z6J/968CtkcSE/7Z2qAJiXbmZ3UDJPGrzqTDHkO30R8VeRM/Kz2f4nR05GIFiITl\n"
+      "4bEjvpy7xqRDspJcCFIOcyXm8abVDhF+th6knSU0yLtNKuQVP6voMrnt9MV1X92L\n"
+      "GZQLgdHZbPQz0Z5qIpaKhdyA8DEvWWvSUwwc+yi1/gGaybwlzZwqXYoPOhwMebzK\n"
+      "Uk0xW14htcJrRrq+PXXQbRzTMynseCoPIoke0dtCodbA3qQxQovE16q9zz4Otv2k\n"
+      "4j63cz53J+mhkVWAeWxVGI0lltJmWtEYK6er8VqqWot3nqmWMXogrgRLggv/Nbbo\n"
+      "oQIDAQAB\n"
+      "-----END RSA PUBLIC KEY-----\n");
+
+  // f9e47d59fbe0fa338ac8c5085201a0dd58dfd88f44abb16756ee5e9d50d52949  key4.pub
+  add_pem(
+      "-----BEGIN RSA PUBLIC KEY-----\n"
+      "MIIBCgKCAQEAvmpxVY7ld/8DAjz6F6q0\n"
+      "5shjg8/4p6047bn6/m8yPy1RBsvIyvuDuGnP/RzPEhzXQ9UJ5Ynmh2XJZgHoE9xb\n"
+      "nfxL5BXHplJhMtADXKM9bWB11PU1Eioc3+AXBB8QiNFBn2XI5UkO5hPhbb9mJpjA\n"
+      "9Uhw8EdfqJP8QetVsI/xrCEbwEXe0xvifRLJbY08/Gp66KpQvy7g8w7VB8wlgePe\n"
+      "xW3pT13Ap6vuC+mQuJPyiHvSxjEKHgqePji9NP3tJUFQjcECqcm0yV7/2d0t/pbC\n"
+      "m+ZH1sadZspQCEPPrtbkQBlvHb4OLiIWPGHKSMeRFvp3IWcmdJqXahxLCUS1Eh6M\n"
+      "AQIDAQAB\n"
+      "-----END RSA PUBLIC KEY-----\n");
+}
+
+void PublicRsaKeyShared::add_rsa(RSA rsa) {
+  auto lock = rw_mutex_.lock_write();
+  auto fingerprint = rsa.get_fingerprint();
+  auto *has_rsa = get_rsa_locked(fingerprint);
+  if (has_rsa) {
+    return;
+  }
+  options_.push_back(RsaOption{fingerprint, std::move(rsa)});
+}
+
+Result<std::pair<RSA, int64>> PublicRsaKeyShared::get_rsa(const vector<int64> &fingerprints) {
+  auto lock = rw_mutex_.lock_read();
+  for (auto fingerprint : fingerprints) {
+    auto *rsa = get_rsa_locked(fingerprint);
+    if (rsa) {
+      return std::make_pair(rsa->clone(), fingerprint);
+    }
+  }
+  return Status::Error("Unknown fingerprints");
+}
+
+void PublicRsaKeyShared::drop_keys() {
+  if (dc_id_.is_empty()) {
+    return;
+  }
+  auto lock = rw_mutex_.lock_write();
+  options_.clear();
+}
+
+bool PublicRsaKeyShared::has_keys() {
+  auto lock = rw_mutex_.lock_read();
+  return !options_.empty();
+}
+
+void PublicRsaKeyShared::add_listener(std::unique_ptr<Listener> listener) {
+  if (listener->notify()) {
+    auto lock = rw_mutex_.lock_write();
+    listeners_.push_back(std::move(listener));
+  }
+}
+
+RSA *PublicRsaKeyShared::get_rsa_locked(int64 fingerprint) {
+  auto it = std::find_if(options_.begin(), options_.end(),
+                         [&](const auto &value) { return value.fingerprint == fingerprint; });
+  if (it == options_.end()) {
+    return nullptr;
+  }
+  return &it->rsa;
+}
+
+void PublicRsaKeyShared::notify() {
+  auto lock = rw_mutex_.lock_read();
+  auto it = std::remove_if(listeners_.begin(), listeners_.end(), [&](auto &listener) { return !listener->notify(); });
+  listeners_.erase(it, listeners_.end());
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/PublicRsaKeyShared.h b/libs/tdlib/td/td/telegram/net/PublicRsaKeyShared.h
new file mode 100644
index 0000000000..453bb7bda1
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/PublicRsaKeyShared.h
@@ -0,0 +1,62 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/net/DcId.h"
+
+#include "td/mtproto/crypto.h"
+
+#include "td/utils/common.h"
+#include "td/utils/port/RwMutex.h"
+#include "td/utils/Status.h"
+
+#include <utility>
+
+namespace td {
+
+class PublicRsaKeyShared : public PublicRsaKeyInterface {
+ public:
+  explicit PublicRsaKeyShared(DcId dc_id);
+
+  class Listener {
+   public:
+    Listener() = default;
+    Listener(const Listener &) = delete;
+    Listener &operator=(const Listener &) = delete;
+    Listener(Listener &&) = delete;
+    Listener &operator=(Listener &&) = delete;
+    virtual ~Listener() = default;
+    virtual bool notify() = 0;
+  };
+
+  void add_rsa(RSA rsa);
+  Result<std::pair<RSA, int64>> get_rsa(const vector<int64> &fingerprints) override;
+  void drop_keys() override;
+  bool has_keys();
+
+  void add_listener(std::unique_ptr<Listener> listener);
+
+  DcId dc_id() const {
+    return dc_id_;
+  }
+
+ private:
+  DcId dc_id_;
+  struct RsaOption {
+    int64 fingerprint;
+    RSA rsa;
+  };
+  std::vector<RsaOption> options_;
+  std::vector<std::unique_ptr<Listener>> listeners_;
+  RwMutex rw_mutex_;
+
+  RSA *get_rsa_locked(int64 fingerprint);
+
+  void notify();
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/PublicRsaKeyWatchdog.cpp b/libs/tdlib/td/td/telegram/net/PublicRsaKeyWatchdog.cpp
new file mode 100644
index 0000000000..5946fca4ca
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/PublicRsaKeyWatchdog.cpp
@@ -0,0 +1,117 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/PublicRsaKeyWatchdog.h"
+
+#include "td/telegram/Global.h"
+
+#include "td/telegram/telegram_api.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/Time.h"
+
+namespace td {
+
+PublicRsaKeyWatchdog::PublicRsaKeyWatchdog(ActorShared<> parent) : parent_(std::move(parent)) {
+}
+
+void PublicRsaKeyWatchdog::add_public_rsa_key(std::shared_ptr<PublicRsaKeyShared> key) {
+  class Listener : public PublicRsaKeyShared::Listener {
+   public:
+    explicit Listener(ActorId<PublicRsaKeyWatchdog> parent) : parent_(std::move(parent)) {
+    }
+    bool notify() override {
+      send_event(parent_, Event::yield());
+      return parent_.is_alive();
+    }
+
+   private:
+    ActorId<PublicRsaKeyWatchdog> parent_;
+  };
+
+  key->add_listener(std::make_unique<Listener>(actor_id(this)));
+  sync_key(key);
+  keys_.push_back(std::move(key));
+  loop();
+}
+
+void PublicRsaKeyWatchdog::start_up() {
+  flood_control_.add_limit(1, 1);
+  flood_control_.add_limit(2, 60);
+  flood_control_.add_limit(3, 2 * 60);
+
+  sync(BufferSlice(G()->td_db()->get_binlog_pmc()->get("cdn_config")));
+}
+
+void PublicRsaKeyWatchdog::loop() {
+  if (has_query_) {
+    return;
+  }
+  if (Time::now_cached() < flood_control_.get_wakeup_at()) {
+    return;
+  }
+  bool ok = true;
+  for (auto &key : keys_) {
+    if (!key->has_keys()) {
+      ok = false;
+    }
+  }
+  if (ok) {
+    return;
+  }
+  flood_control_.add_event(static_cast<int32>(Time::now_cached()));
+  has_query_ = true;
+  G()->net_query_dispatcher().dispatch_with_callback(
+      G()->net_query_creator().create(create_storer(telegram_api::help_getCdnConfig()), DcId::main(),
+                                      NetQuery::Type::Common, NetQuery::AuthFlag::Off, NetQuery::GzipFlag::On,
+                                      60 * 60 * 24),
+      actor_shared(this));
+}
+
+void PublicRsaKeyWatchdog::on_result(NetQueryPtr net_query) {
+  has_query_ = false;
+  yield();
+  if (net_query->is_error()) {
+    LOG(ERROR) << "getCdnConfig error " << net_query->move_as_error();
+    return;
+  }
+
+  auto buf = net_query->move_as_ok();
+  G()->td_db()->get_binlog_pmc()->set("cdn_config", buf.as_slice().str());
+  sync(std::move(buf));
+}
+
+void PublicRsaKeyWatchdog::sync(BufferSlice cdn_config_serialized) {
+  if (cdn_config_serialized.empty()) {
+    return;
+  }
+  auto r_keys = fetch_result<telegram_api::help_getCdnConfig>(cdn_config_serialized);
+  if (r_keys.is_error()) {
+    LOG(WARNING) << "Failed to deserialize help_getCdnConfig (probably not a problem) " << r_keys.error();
+    return;
+  }
+  cdn_config_ = r_keys.move_as_ok();
+  for (auto &key : keys_) {
+    sync_key(key);
+  }
+}
+
+void PublicRsaKeyWatchdog::sync_key(std::shared_ptr<PublicRsaKeyShared> &key) {
+  if (!cdn_config_) {
+    return;
+  }
+  for (auto &config_key : cdn_config_->public_keys_) {
+    if (key->dc_id().get_raw_id() == config_key->dc_id_) {
+      auto r_rsa = RSA::from_pem(config_key->public_key_);
+      if (r_rsa.is_error()) {
+        LOG(ERROR) << r_rsa.error();
+        continue;
+      }
+      key->add_rsa(r_rsa.move_as_ok());
+    }
+  }
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/PublicRsaKeyWatchdog.h b/libs/tdlib/td/td/telegram/net/PublicRsaKeyWatchdog.h
new file mode 100644
index 0000000000..ff6fa39424
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/PublicRsaKeyWatchdog.h
@@ -0,0 +1,46 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/net/PublicRsaKeyShared.h"
+
+#include "td/telegram/net/NetActor.h"
+#include "td/telegram/net/NetQueryCreator.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+
+#include "td/telegram/telegram_api.h"
+
+#include "td/actor/actor.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/FloodControlStrict.h"
+
+#include <memory>
+
+namespace td {
+class PublicRsaKeyWatchdog : public NetActor {
+ public:
+  explicit PublicRsaKeyWatchdog(ActorShared<> parent);
+
+  void add_public_rsa_key(std::shared_ptr<PublicRsaKeyShared> key);
+
+ private:
+  ActorShared<> parent_;
+  vector<std::shared_ptr<PublicRsaKeyShared>> keys_;
+  tl_object_ptr<telegram_api::cdnConfig> cdn_config_;
+  FloodControlStrict flood_control_;
+  bool has_query_{false};
+
+  void start_up() override;
+  void loop() override;
+
+  void on_result(NetQueryPtr net_query) override;
+  void sync(BufferSlice cdn_config_serialized);
+  void sync_key(std::shared_ptr<PublicRsaKeyShared> &key);
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/Session.cpp b/libs/tdlib/td/td/telegram/net/Session.cpp
new file mode 100644
index 0000000000..25759a87d7
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/Session.cpp
@@ -0,0 +1,1190 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/Session.h"
+
+#include "td/telegram/telegram_api.h"
+
+#include "td/telegram/DhCache.h"
+#include "td/telegram/Global.h"
+#include "td/telegram/net/MtprotoHeader.h"
+#include "td/telegram/net/NetQuery.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+#include "td/telegram/StateManager.h"
+#include "td/telegram/UniqueId.h"
+
+#include "td/mtproto/Handshake.h"
+#include "td/mtproto/HandshakeActor.h"
+#include "td/mtproto/RawConnection.h"
+#include "td/mtproto/SessionConnection.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Random.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Time.h"
+#include "td/utils/Timer.h"
+#include "td/utils/tl_parsers.h"
+
+#include <algorithm>
+#include <tuple>
+#include <utility>
+
+namespace td {
+
+namespace detail {
+class GenAuthKeyActor : public Actor {
+ public:
+  GenAuthKeyActor(std::unique_ptr<mtproto::AuthKeyHandshake> handshake,
+                  std::unique_ptr<mtproto::AuthKeyHandshakeContext> context,
+                  Promise<std::unique_ptr<mtproto::RawConnection>> connection_promise,
+                  Promise<std::unique_ptr<mtproto::AuthKeyHandshake>> handshake_promise,
+                  std::shared_ptr<Session::Callback> callback)
+      : handshake_(std::move(handshake))
+      , context_(std::move(context))
+      , connection_promise_(std::move(connection_promise))
+      , handshake_promise_(std::move(handshake_promise))
+      , callback_(std::move(callback)) {
+  }
+
+  void on_network(uint32 network_generation) {
+    if (network_generation_ != network_generation) {
+      send_closure(std::move(child_), &mtproto::HandshakeActor::close);
+    }
+  }
+
+ private:
+  uint32 network_generation_ = 0;
+  std::unique_ptr<mtproto::AuthKeyHandshake> handshake_;
+  std::unique_ptr<mtproto::AuthKeyHandshakeContext> context_;
+  Promise<std::unique_ptr<mtproto::RawConnection>> connection_promise_;
+  Promise<std::unique_ptr<mtproto::AuthKeyHandshake>> handshake_promise_;
+  std::shared_ptr<Session::Callback> callback_;
+
+  ActorOwn<mtproto::HandshakeActor> child_;
+
+  void start_up() override {
+    // Bug in Android clang and MSVC
+    // std::tuple<Result<int>> b(std::forward_as_tuple(Result<int>()));
+
+    callback_->request_raw_connection(PromiseCreator::lambda(
+        [actor_id = actor_id(this)](Result<std::unique_ptr<mtproto::RawConnection>> r_raw_connection) {
+          send_closure(actor_id, &GenAuthKeyActor::on_connection, std::move(r_raw_connection), false);
+        }));
+  }
+
+  void on_connection(Result<std::unique_ptr<mtproto::RawConnection>> r_raw_connection, bool dummy) {
+    if (r_raw_connection.is_error()) {
+      connection_promise_.set_error(r_raw_connection.move_as_error());
+      handshake_promise_.set_value(std::move(handshake_));
+      return;
+    }
+    auto raw_connection = r_raw_connection.move_as_ok();
+    network_generation_ = raw_connection->extra_;
+    child_ = create_actor_on_scheduler<mtproto::HandshakeActor>(
+        "HandshakeActor", G()->get_slow_net_scheduler_id(), std::move(handshake_), std::move(raw_connection),
+        std::move(context_), 10, std::move(connection_promise_), std::move(handshake_promise_));
+  }
+};
+}  // namespace detail
+
+Session::Session(unique_ptr<Callback> callback, std::shared_ptr<AuthDataShared> shared_auth_data, bool is_main,
+                 bool use_pfs, bool is_cdn, const mtproto::AuthKey &tmp_auth_key) {
+  VLOG(dc) << "Start connection";
+
+  shared_auth_data_ = std::move(shared_auth_data);
+  auth_data_.set_use_pfs(use_pfs);
+  auth_data_.set_main_auth_key(shared_auth_data_->get_auth_key());
+  auth_data_.set_server_time_difference(shared_auth_data_->get_server_time_difference());
+  auth_data_.set_future_salts(shared_auth_data_->get_future_salts(), Time::now());
+  if (use_pfs && !tmp_auth_key.empty()) {
+    auth_data_.set_tmp_auth_key(tmp_auth_key);
+  }
+  uint64 session_id = 0;
+  Random::secure_bytes(reinterpret_cast<uint8 *>(&session_id), sizeof(session_id));
+  auth_data_.session_id_ = session_id;
+  LOG(WARNING) << "Generate new session_id " << session_id << " for auth key " << auth_data_.get_auth_key().id();
+
+  callback_ = std::shared_ptr<Callback>(callback.release());
+
+  main_connection_.connection_id = 0;
+  long_poll_connection_.connection_id = 1;
+
+  is_main_ = is_main;
+  is_cdn_ = is_cdn;
+  if (is_cdn) {
+    auth_data_.set_header(G()->mtproto_header().get_anonymous_header().str());
+  } else {
+    auth_data_.set_header(G()->mtproto_header().get_default_header().str());
+  }
+  last_activity_timestamp_ = Time::now();
+}
+
+void Session::start_up() {
+  class StateCallback : public StateManager::Callback {
+   public:
+    explicit StateCallback(ActorId<Session> session) : session_(std::move(session)) {
+    }
+    bool on_network(NetType network_type, uint32 network_generation) override {
+      send_closure(session_, &Session::on_network, network_type != NetType::None, network_generation);
+      return session_.is_alive();
+    }
+    bool on_online(bool online_flag) override {
+      send_closure(session_, &Session::on_online, online_flag);
+      return session_.is_alive();
+    }
+
+   private:
+    ActorId<Session> session_;
+  };
+  send_closure(G()->state_manager(), &StateManager::add_callback, make_unique<StateCallback>(actor_id(this)));
+
+  yield();
+}
+
+void Session::on_network(bool network_flag, uint32 network_generation) {
+  was_on_network_ = true;
+  network_flag_ = network_flag;
+  if (network_generation_ != network_generation) {
+    network_generation_ = network_generation;
+    connection_close(&main_connection_);
+    connection_close(&long_poll_connection_);
+  }
+
+  for (auto &handshake_info : handshake_info_) {
+    if (handshake_info.actor_.empty()) {
+      continue;
+    }
+    send_closure(handshake_info.actor_, &detail::GenAuthKeyActor::on_network, network_generation);
+  }
+
+  loop();
+}
+
+void Session::on_online(bool online_flag) {
+  online_flag_ = online_flag;
+  connection_online_update(true);
+  loop();
+}
+
+void Session::connection_online_update(bool force) {
+  bool new_connection_online_flag =
+      online_flag_ && (has_queries() || last_activity_timestamp_ + 10 > Time::now_cached() || is_main_);
+  if (connection_online_flag_ == new_connection_online_flag && !force) {
+    return;
+  }
+  connection_online_flag_ = new_connection_online_flag;
+  LOG(INFO) << "Set connection_online " << connection_online_flag_;
+  if (is_main_) {
+    if (main_connection_.connection) {
+      main_connection_.connection->set_online(connection_online_flag_);
+    }
+    if (long_poll_connection_.connection) {
+      long_poll_connection_.connection->set_online(connection_online_flag_);
+    }
+  } else {
+    // TODO: support online state in media connections.
+    if (connection_online_flag_) {
+      connection_close(&main_connection_);
+      connection_close(&long_poll_connection_);
+    }
+    return;
+  }
+}
+
+void Session::send(NetQueryPtr &&query) {
+  last_activity_timestamp_ = Time::now();
+
+  query->debug("Session: received from DataCenter");
+  query->set_session_id(auth_data_.session_id_);
+  VLOG(net_query) << "got query " << query;
+  if (query->update_is_ready()) {
+    return_query(std::move(query));
+    return;
+  }
+  add_query(std::move(query));
+  loop();
+}
+
+void Session::on_result(NetQueryPtr query) {
+  CHECK(UniqueId::extract_type(query->id()) == UniqueId::BindKey);
+  if (last_bind_id_ != query->id()) {
+    query->clear();
+    return;
+  }
+
+  LOG(INFO) << "ANSWER TO BindKey" << query;
+  Status status;
+  tmp_auth_key_id_ = 0;
+  last_bind_id_ = 0;
+  if (query->is_error()) {
+    status = std::move(query->error());
+  } else {
+    auto r_flag = fetch_result<telegram_api::auth_bindTempAuthKey>(query->ok());
+    if (r_flag.is_error()) {
+      status = r_flag.move_as_error();
+    } else {
+      auto flag = r_flag.move_as_ok();
+      if (!flag) {
+        status = Status::Error("Returned false");
+      }
+    }
+  }
+  if (status.is_ok()) {
+    LOG(INFO) << "BOUND!" << tag("tmp_id", auth_data_.get_tmp_auth_key().id());
+    auth_data_.on_bind();
+    on_tmp_auth_key_updated();
+  } else {
+    LOG(ERROR) << "BindKey failed: " << status;
+  }
+  query->clear();
+  yield();
+}
+
+void Session::return_query(NetQueryPtr &&query) {
+  last_activity_timestamp_ = Time::now();
+
+  query->set_session_id(0);
+  G()->net_query_dispatcher().dispatch(std::move(query));
+}
+
+void Session::flush_pending_invoke_after_queries() {
+  while (!pending_invoke_after_queries_.empty()) {
+    auto &query = pending_invoke_after_queries_.front();
+    pending_queries_.push_back(std::move(query));
+    pending_invoke_after_queries_.pop_front();
+  }
+}
+
+void Session::close() {
+  close_flag_ = true;
+  connection_close(&main_connection_);
+  connection_close(&long_poll_connection_);
+
+  for (auto &it : sent_queries_) {
+    auto &query = it.second.query;
+    query->set_message_id(0);
+    query->cancel_slot_.clear_event();
+    pending_queries_.push_back(std::move(query));
+  }
+  sent_queries_.clear();
+  sent_containers_.clear();
+
+  flush_pending_invoke_after_queries();
+  CHECK(sent_queries_.empty());
+  while (!pending_queries_.empty()) {
+    auto &query = pending_queries_.front();
+    query->set_error_resend();
+    return_query(std::move(query));
+    pending_queries_.pop_front();
+  }
+
+  callback_->on_closed();
+  stop();
+}
+
+void Session::hangup() {
+  LOG(DEBUG) << "HANGUP";
+  close();
+}
+
+void Session::raw_event(const Event::Raw &event) {
+  auto message_id = event.u64;
+  auto it = sent_queries_.find(message_id);
+  if (it == sent_queries_.end()) {
+    return;
+  }
+
+  dec_container(it->first, &it->second);
+  mark_as_known(it->first, &it->second);
+
+  auto query = std::move(it->second.query);
+  query->set_message_id(0);
+  query->cancel_slot_.clear_event();
+  sent_queries_.erase(it);
+  return_query(std::move(query));
+
+  LOG(DEBUG) << "Drop answer " << tag("message_id", format::as_hex(message_id));
+  if (main_connection_.state == ConnectionInfo::State::Ready) {
+    main_connection_.connection->cancel_answer(message_id);
+  } else {
+    to_cancel_.push_back(message_id);
+  }
+  loop();
+}
+
+/** Connection::Callback **/
+void Session::on_connected() {
+  if (is_main_) {
+    connection_token_ = StateManager::connection(G()->state_manager());
+  }
+}
+Status Session::on_pong() {
+  constexpr int MAX_QUERY_TIMEOUT = 60;
+  constexpr int MIN_CONNECTION_ACTIVE = 60;
+  if (current_info_ == &main_connection_ &&
+      Timestamp::at(current_info_->created_at_ + MIN_CONNECTION_ACTIVE).is_in_past()) {
+    Status status;
+    if (!unknown_queries_.empty()) {
+      status = Status::Error(PSLICE() << "No state info for " << unknown_queries_.size() << " queries for "
+                                      << format::as_time(Time::now_cached() - current_info_->created_at_));
+    }
+    if (!sent_queries_list_.empty()) {
+      for (auto it = sent_queries_list_.prev; it != &sent_queries_list_; it = it->prev) {
+        auto query = Query::from_list_node(it);
+        if (Timestamp::at(query->sent_at_ + MAX_QUERY_TIMEOUT).is_in_past()) {
+          if (status.is_ok()) {
+            status = Status::Error(PSLICE() << "No answer for " << query->query << " for "
+                                            << format::as_time(Time::now_cached() - query->sent_at_));
+          }
+          query->ack = false;
+        } else {
+          break;
+        }
+      }
+      if (status.is_error()) {
+        return status;
+      }
+    }
+  }
+  return Status::OK();
+}
+void Session::on_auth_key_updated() {
+  shared_auth_data_->set_auth_key(auth_data_.get_main_auth_key());
+}
+void Session::on_tmp_auth_key_updated() {
+  callback_->on_tmp_auth_key_updated(auth_data_.get_tmp_auth_key());
+}
+
+void Session::on_server_salt_updated() {
+  if (auth_data_.use_pfs()) {
+    return;
+  }
+  shared_auth_data_->set_future_salts(auth_data_.get_future_salts());
+}
+
+void Session::on_server_time_difference_updated() {
+  shared_auth_data_->update_server_time_difference(auth_data_.get_server_time_difference());
+}
+
+void Session::on_before_close() {
+  unsubscribe_before_close(current_info_->connection->get_pollable());
+}
+
+void Session::on_closed(Status status) {
+  if (!close_flag_ && is_main_) {
+    connection_token_.reset();
+  }
+
+  if (status.is_error()) {
+    LOG(WARNING) << "on_closed: " << status << " " << current_info_->connection->get_name();
+  } else {
+    LOG(INFO) << "on_closed: " << status << " " << current_info_->connection->get_name();
+  }
+
+  if (status.is_error() && status.code() == -404) {
+    if (auth_data_.use_pfs()) {
+      LOG(WARNING) << "Invalidate tmp_key";
+      auth_data_.drop_tmp_auth_key();
+      on_tmp_auth_key_updated();
+      yield();
+    } else if (is_cdn_) {
+      LOG(WARNING) << "Invalidate cdn tmp_key";
+      auth_data_.drop_main_auth_key();
+      on_auth_key_updated();
+      on_session_failed(std::move(status));
+    }
+  }
+
+  // resend all queries without ack.
+  for (auto it = sent_queries_.begin(); it != sent_queries_.end();) {
+    if (!it->second.ack && it->second.connection_id == current_info_->connection_id) {
+      // container vector leak otherwise
+      cleanup_container(it->first, &it->second);
+
+      // mark query as unknown
+      if (status.is_error() && status.code() == 500) {
+        cleanup_container(it->first, &it->second);
+        mark_as_known(it->first, &it->second);
+
+        auto &query = it->second.query;
+        VLOG(net_query) << "resend query (on_disconnected, no ack) " << query;
+        query->set_message_id(0);
+        query->cancel_slot_.clear_event();
+        query->set_error(Status::Error(500, "Session failed: " + status.message().str()),
+                         current_info_->connection->get_name().str());
+        return_query(std::move(query));
+        it = sent_queries_.erase(it);
+      } else {
+        mark_as_unknown(it->first, &it->second);
+        it++;
+      }
+    } else {
+      ++it;
+    }
+  }
+
+  current_info_->connection.reset();
+  current_info_->state = ConnectionInfo::State::Empty;
+}
+
+void Session::on_session_created(uint64 unique_id, uint64 first_id) {
+  // TODO: use unique_id
+  // send updatesTooLong to force getDifference
+  LOG(INFO) << "new_session_created " << unique_id << " " << first_id;
+  if (is_main_) {
+    LOG(INFO) << "Sending updatesTooLong to force getDifference";
+    telegram_api::updatesTooLong too_long_;
+    auto storer = create_storer(too_long_);
+    BufferSlice packet(storer.size());
+    storer.store(packet.as_slice().ubegin());
+    return_query(G()->net_query_creator().create_result(0, std::move(packet)));
+  }
+
+  for (auto it = sent_queries_.begin(); it != sent_queries_.end();) {
+    Query *query_ptr = &it->second;
+    if (query_ptr->container_id < first_id) {
+      // container vector leak otherwise
+      cleanup_container(it->first, &it->second);
+      mark_as_known(it->first, &it->second);
+
+      auto &query = it->second.query;
+      VLOG(net_query) << "resend query (on_session_created) " << query;
+      query->set_message_id(0);
+      query->cancel_slot_.clear_event();
+      resend_query(std::move(query));
+      it = sent_queries_.erase(it);
+    } else {
+      ++it;
+    }
+  }
+}
+
+void Session::on_session_failed(Status status) {
+  if (status.is_error()) {
+    LOG(WARNING) << "Session failed: " << status;
+  } else {
+    LOG(INFO) << "Session will be closed soon";
+  }
+  // this connection will be closed soon
+  close_flag_ = true;
+  callback_->on_failed();
+}
+
+void Session::on_container_sent(uint64 container_id, vector<uint64> msg_ids) {
+  auto erase_from = std::remove_if(msg_ids.begin(), msg_ids.end(), [&](uint64 msg_id) {
+    auto it = sent_queries_.find(msg_id);
+    if (it == sent_queries_.end()) {
+      return true;  // remove
+    }
+    it->second.container_id = container_id;
+    return false;
+  });
+  msg_ids.erase(erase_from, msg_ids.end());
+  if (msg_ids.empty()) {
+    return;
+  }
+  auto size = msg_ids.size();
+  sent_containers_.emplace(container_id, ContainerInfo{size, std::move(msg_ids)});
+}
+
+void Session::on_message_ack(uint64 id) {
+  on_message_ack_impl(id, 1);
+}
+void Session::on_message_ack_impl(uint64 id, int32 type) {
+  auto cit = sent_containers_.find(id);
+  if (cit != sent_containers_.end()) {
+    auto container_info = std::move(cit->second);
+    for (auto message_id : container_info.message_ids) {
+      on_message_ack_impl_inner(message_id, type, true);
+    }
+    sent_containers_.erase(cit);
+    return;
+  }
+
+  on_message_ack_impl_inner(id, type, false);
+}
+
+void Session::on_message_ack_impl_inner(uint64 id, int32 type, bool in_container) {
+  auto it = sent_queries_.find(id);
+  if (it == sent_queries_.end()) {
+    return;
+  }
+  VLOG(net_query) << "Ack " << tag("msg_id", id) << it->second.query;
+  it->second.ack = true;
+  it->second.query->debug_ack |= type;
+  it->second.query->quick_ack_promise_.set_value(Unit());
+  if (!in_container) {
+    cleanup_container(id, &it->second);
+  }
+  mark_as_known(it->first, &it->second);
+}
+
+void Session::dec_container(uint64 message_id, Query *query) {
+  if (query->container_id == message_id) {
+    // message was sent without any container
+    return;
+  }
+  auto it = sent_containers_.find(query->container_id);
+  if (it == sent_containers_.end()) {
+    return;
+  }
+  CHECK(it->second.ref_cnt > 0);
+  it->second.ref_cnt--;
+  if (it->second.ref_cnt == 0) {
+    sent_containers_.erase(it);
+  }
+}
+void Session::cleanup_container(uint64 message_id, Query *query) {
+  if (query->container_id == message_id) {
+    // message was sent without any container
+    return;
+  }
+
+  // we can forget container now, since we have an answer for its part.
+  // TODO: we can do it only for one element per container
+  sent_containers_.erase(query->container_id);
+}
+
+void Session::mark_as_known(uint64 id, Query *query) {
+  query->query->debug_unknown = false;
+  if (!query->unknown) {
+    return;
+  }
+  VLOG(net_query) << "Mark as known " << tag("msg_id", id) << query->query;
+  query->unknown = false;
+  unknown_queries_.erase(id);
+  if (unknown_queries_.empty()) {
+    flush_pending_invoke_after_queries();
+  }
+}
+
+void Session::mark_as_unknown(uint64 id, Query *query) {
+  query->query->debug_unknown = true;
+  if (query->unknown) {
+    return;
+  }
+  VLOG(net_query) << "Mark as unknown " << tag("msg_id", id) << query->query;
+  query->unknown = true;
+  unknown_queries_.insert(id);
+}
+
+Status Session::on_message_result_ok(uint64 id, BufferSlice packet, size_t original_size) {
+  // Steal authorization information.
+  // It is a dirty hack, yep.
+  TlParser parser(packet.as_slice());
+  int32 ID = parser.fetch_int();
+  if (!parser.get_error()) {
+    if (ID == telegram_api::auth_authorization::ID) {
+      LOG(INFO) << "GOT AUTHORIZATION!";
+      auth_data_.set_auth_flag(true);
+      shared_auth_data_->set_auth_key(auth_data_.get_main_auth_key());
+    }
+  }
+
+  if (id == 0) {
+    if (is_cdn_) {
+      return Status::Error("Got update from CDN connection");
+    }
+    return_query(G()->net_query_creator().create_result(0, std::move(packet)));
+    return Status::OK();
+  }
+  auto it = sent_queries_.find(id);
+  if (it == sent_queries_.end()) {
+    LOG(DEBUG) << "DROP result to " << tag("request_id", format::as_hex(id)) << tag("tl", format::as_hex(ID));
+
+    if (packet.size() > 16 * 1024) {
+      dropped_size_ += packet.size();
+      if (dropped_size_ > (256 * 1024)) {
+        auto dropped_size = dropped_size_;
+        dropped_size_ = 0;
+        return Status::Error(
+            2, PSLICE() << "Too much dropped packets " << tag("total_size", format::as_size(dropped_size)));
+      }
+    }
+    return Status::OK();
+  }
+  auth_data_.on_api_response();
+  Query *query_ptr = &it->second;
+  VLOG(net_query) << "return query result " << query_ptr->query;
+
+  cleanup_container(id, query_ptr);
+  mark_as_known(id, query_ptr);
+  query_ptr->query->on_net_read(original_size);
+  query_ptr->query->set_ok(std::move(packet));
+  query_ptr->query->set_message_id(0);
+  query_ptr->query->cancel_slot_.clear_event();
+  return_query(std::move(query_ptr->query));
+
+  sent_queries_.erase(it);
+  return Status::OK();
+}
+
+void Session::on_message_result_error(uint64 id, int error_code, BufferSlice message) {
+  // UNAUTHORIZED
+  // TODO: some errors shouldn't cause loss of authorizations. Especially when PFS will be used
+  if (error_code == 401 && message.as_slice() != CSlice("SESSION_PASSWORD_NEEDED")) {
+    if (auth_data_.use_pfs() && message.as_slice() == CSlice("AUTH_KEY_PERM_EMPTY")) {
+      LOG(ERROR) << "Receive AUTH_KEY_PERM_EMPTY in session " << auth_data_.session_id_ << " for auth key "
+                 << auth_data_.get_tmp_auth_key().id();
+      auth_data_.drop_tmp_auth_key();
+      on_tmp_auth_key_updated();
+      error_code = 500;
+    } else {
+      LOG(WARNING) << "Lost authorization due to " << tag("msg", message.as_slice());
+      auth_data_.set_auth_flag(false);
+      shared_auth_data_->set_auth_key(auth_data_.get_main_auth_key());
+      auth_lost_flag_ = true;
+    }
+  }
+
+  if (id == 0) {
+    LOG(WARNING) << "Session got error update";
+    return;
+  }
+
+  LOG(DEBUG) << "Session::on_error " << tag("id", id) << tag("error_code", error_code)
+             << tag("msg", message.as_slice());
+  auto it = sent_queries_.find(id);
+  if (it == sent_queries_.end()) {
+    return;
+  }
+
+  Query *query_ptr = &it->second;
+  VLOG(net_query) << "return query error " << query_ptr->query;
+
+  cleanup_container(id, query_ptr);
+  mark_as_known(id, query_ptr);
+  query_ptr->query->set_error(Status::Error(error_code, message.as_slice()),
+                              current_info_->connection->get_name().str());
+  query_ptr->query->set_message_id(0);
+  query_ptr->query->cancel_slot_.clear_event();
+  return_query(std::move(query_ptr->query));
+
+  sent_queries_.erase(it);
+}
+
+void Session::on_message_failed_inner(uint64 id, bool in_container) {
+  LOG(INFO) << "message inner failed " << id;
+  auto it = sent_queries_.find(id);
+  if (it == sent_queries_.end()) {
+    return;
+  }
+
+  Query *query_ptr = &it->second;
+  if (!in_container) {
+    cleanup_container(id, query_ptr);
+  }
+  mark_as_known(id, query_ptr);
+
+  query_ptr->query->set_message_id(0);
+  query_ptr->query->cancel_slot_.clear_event();
+  query_ptr->query->debug_send_failed();
+  resend_query(std::move(query_ptr->query));
+  sent_queries_.erase(it);
+}
+
+void Session::on_message_failed(uint64 id, Status status) {
+  LOG(INFO) << "on_message_failed " << tag("id", id) << tag("status", status);
+  status.ignore();
+
+  auto cit = sent_containers_.find(id);
+  if (cit != sent_containers_.end()) {
+    auto container_info = std::move(cit->second);
+    for (auto message_id : container_info.message_ids) {
+      on_message_failed_inner(message_id, true);
+    }
+    sent_containers_.erase(cit);
+    return;
+  }
+
+  on_message_failed_inner(id, false);
+}
+
+void Session::on_message_info(uint64 id, int32 state, uint64 answer_id, int32 answer_size) {
+  auto it = sent_queries_.find(id);
+  if (it != sent_queries_.end()) {
+    if (it->second.query->update_is_ready()) {
+      dec_container(it->first, &it->second);
+      mark_as_known(it->first, &it->second);
+
+      auto query = std::move(it->second.query);
+      query->set_message_id(0);
+      query->cancel_slot_.clear_event();
+      sent_queries_.erase(it);
+      return_query(std::move(query));
+      return;
+    }
+  }
+  if (id != 0) {
+    if (it == sent_queries_.end()) {
+      return;
+    }
+    switch (state & 7) {
+      case 1:
+      case 2:
+      case 3:
+        // message not received by server
+        return on_message_failed(id, Status::Error("Unknown message id"));
+      case 0:
+        if (answer_id == 0) {
+          LOG(ERROR) << "Unexpected message_info.state == 0 " << tag("id", id) << tag("state", state)
+                     << tag("answer_id", answer_id);
+          return on_message_failed(id, Status::Error("Unexpected message_info.state == 0"));
+        }
+      // fallthrough
+      case 4:
+        on_message_ack_impl(id, 2);
+        break;
+      default:
+        LOG(ERROR) << "Invalid message info " << tag("state", state);
+    }
+  }
+
+  // ok, we are waiting for result of id. let's ask to resend it
+  if (answer_id != 0) {
+    if (it != sent_queries_.end()) {
+      VLOG_IF(net_query, id != 0) << "Resend answer " << tag("msg_id", id) << tag("answer_id", answer_id)
+                                  << tag("answer_size", answer_size) << it->second.query;
+      it->second.query->debug("Session: resend answer");
+    }
+    current_info_->connection->resend_answer(answer_id);
+  }
+}
+
+bool Session::has_queries() const {
+  return !pending_invoke_after_queries_.empty() || !pending_queries_.empty() || !sent_queries_.empty();
+}
+
+void Session::resend_query(NetQueryPtr query) {
+  if (UniqueId::extract_type(query->id()) == UniqueId::BindKey) {
+    query->set_error_resend();
+    return_query(std::move(query));
+  } else {
+    add_query(std::move(query));
+  }
+}
+
+void Session::add_query(NetQueryPtr &&net_query) {
+  net_query->debug("Session: pending");
+  LOG_IF(FATAL, UniqueId::extract_type(net_query->id()) == UniqueId::BindKey)
+      << "Add BindKey query inpo pending_queries_";
+  pending_queries_.emplace_back(std::move(net_query));
+}
+
+void Session::connection_send_query(ConnectionInfo *info, NetQueryPtr &&net_query, uint64 message_id) {
+  net_query->debug("Session: try send to mtproto::connection");
+  CHECK(info->state == ConnectionInfo::State::Ready);
+  current_info_ = info;
+
+  if (net_query->update_is_ready()) {
+    return return_query(std::move(net_query));
+  }
+
+  uint64 invoke_after_id = 0;
+  NetQueryRef invoke_after = net_query->invoke_after();
+  if (!invoke_after.empty()) {
+    invoke_after_id = invoke_after->message_id();
+    if (invoke_after->session_id() != auth_data_.session_id_ || invoke_after_id == 0) {
+      net_query->set_error_resend_invoke_after();
+      return return_query(std::move(net_query));
+    }
+    if (!unknown_queries_.empty()) {
+      pending_invoke_after_queries_.push_back(std::move(net_query));
+      return;
+    }
+  }
+
+  net_query->debug("Session: send to mtproto::connection");
+  auto r_message_id =
+      info->connection->send_query(net_query->query().clone(), net_query->gzip_flag() == NetQuery::GzipFlag::On,
+                                   message_id, invoke_after_id, static_cast<bool>(net_query->quick_ack_promise_));
+
+  net_query->on_net_write(net_query->query().size());
+
+  if (r_message_id.is_error()) {
+    LOG(FATAL) << "Failed to send query: " << r_message_id.error();
+  }
+  message_id = r_message_id.ok();
+  VLOG(net_query) << "send query to connection " << net_query << " [msg_id:" << format::as_hex(message_id) << "]"
+                  << tag("invoke_after", format::as_hex(invoke_after_id));
+  net_query->set_message_id(message_id);
+  net_query->cancel_slot_.clear_event();
+  CHECK(sent_queries_.find(message_id) == sent_queries_.end()) << message_id;
+  net_query->debug_unknown = false;
+  net_query->debug_ack = 0;
+  if (!net_query->cancel_slot_.empty()) {
+    LOG(DEBUG) << "set event for net_query cancellation " << tag("message_id", format::as_hex(message_id));
+    net_query->cancel_slot_.set_event(EventCreator::raw(actor_id(), message_id));
+  }
+  auto status = sent_queries_.emplace(
+      message_id, Query{message_id, std::move(net_query), main_connection_.connection_id, Time::now_cached()});
+  sent_queries_list_.put(status.first->second.get_list_node());
+  if (!status.second) {
+    LOG(FATAL) << "Duplicate message_id oO [message_id=" << message_id << "]";
+  }
+}
+
+void Session::connection_open(ConnectionInfo *info, bool ask_info) {
+  CHECK(info->state == ConnectionInfo::State::Empty);
+  if (!network_flag_) {
+    return;
+  }
+  if (!auth_data_.has_auth_key(Time::now_cached())) {
+    return;
+  }
+  info->ask_info = ask_info;
+
+  info->state = ConnectionInfo::State::Connecting;
+  // NB: rely on constant location of info
+  auto promise = PromiseCreator::lambda(
+      [actor_id = actor_id(this), info = info](Result<std::unique_ptr<mtproto::RawConnection>> res) {
+        send_closure(actor_id, &Session::connection_open_finish, info, std::move(res));
+      });
+
+  if (cached_connection_) {
+    LOG(INFO) << "Reuse cached connection";
+    promise.set_value(std::move(cached_connection_));
+  } else {
+    callback_->request_raw_connection(std::move(promise));
+  }
+
+  info->wakeup_at = Time::now_cached() + 1000;
+}
+
+void Session::connection_add(std::unique_ptr<mtproto::RawConnection> raw_connection) {
+  LOG(INFO) << "Cache connection";
+  cached_connection_ = std::move(raw_connection);
+  cached_connection_timestamp_ = Time::now();
+}
+
+void Session::connection_check_mode(ConnectionInfo *info) {
+  if (close_flag_ || info->state != ConnectionInfo::State::Ready) {
+    return;
+  }
+  if (info->mode != mode_) {
+    LOG(WARNING) << "Close connection because of outdated mode_";
+    connection_close(info);
+  }
+}
+
+void Session::connection_open_finish(ConnectionInfo *info,
+                                     Result<std::unique_ptr<mtproto::RawConnection>> r_raw_connection) {
+  if (close_flag_ || info->state != ConnectionInfo::State::Connecting) {
+    return;
+  }
+  current_info_ = info;
+  // Create new connection
+  if (r_raw_connection.is_error()) {
+    LOG(WARNING) << "Failed to open socket: " << r_raw_connection.error();
+    info->state = ConnectionInfo::State::Empty;
+    yield();
+    return;
+  }
+
+  auto raw_connection = r_raw_connection.move_as_ok();
+  if (raw_connection->extra_ != network_generation_) {
+    LOG(WARNING) << "Got RawConnection with old network_generation";
+    info->state = ConnectionInfo::State::Empty;
+    yield();
+    return;
+  }
+
+  Mode expected_mode = raw_connection->get_transport_type() == mtproto::TransportType::Http ? Mode::Http : Mode::Tcp;
+  if (mode_ != expected_mode) {
+    LOG(INFO) << "Change mode " << mode_ << "--->" << expected_mode;
+    mode_ = expected_mode;
+    if (info->connection_id == 1 && mode_ != Mode::Http) {
+      LOG(WARNING) << "Got tcp connection, for long poll connection";
+      connection_add(std::move(raw_connection));
+      info->state = ConnectionInfo::State::Empty;
+      yield();
+      return;
+    }
+  }
+
+  // mtproto::TransportType transport_type = raw_connection->get_transport_type();
+  mtproto::SessionConnection::Mode mode;
+  Slice mode_name;
+  if (mode_ == Mode::Tcp) {
+    mode = mtproto::SessionConnection::Mode::Tcp;
+    mode_name = "Tcp";
+  } else {
+    if (info->connection_id == 0) {
+      mode = mtproto::SessionConnection::Mode::Http;
+      mode_name = "Http";
+    } else {
+      mode = mtproto::SessionConnection::Mode::HttpLongPoll;
+      mode_name = "HttpLongPoll";
+    }
+  }
+  auto name = PSTRING() << get_name() << "::Connect::" << mode_name << "::" << raw_connection->debug_str_;
+  info->connection =
+      make_unique<mtproto::SessionConnection>(mode, std::move(raw_connection), &auth_data_, DhCache::instance());
+  if (is_main_) {
+    info->connection->set_online(connection_online_flag_);
+  }
+  info->connection->set_name(name);
+  info->connection->get_pollable().set_observer(this);
+  subscribe(info->connection->get_pollable());
+  info->mode = mode_;
+  info->state = ConnectionInfo::State::Ready;
+  info->created_at_ = Time::now_cached();
+  info->wakeup_at = Time::now_cached() + 10;
+  if (unknown_queries_.size() > 1024) {
+    on_session_failed(Status::Error("Too much queries with unknown state"));
+    return;
+  }
+  if (info->ask_info) {
+    for (auto &id : unknown_queries_) {
+      info->connection->get_state_info(id);
+    }
+    for (auto &id : to_cancel_) {
+      info->connection->cancel_answer(id);
+    }
+    to_cancel_.clear();
+  }
+  yield();
+}
+
+void Session::connection_flush(ConnectionInfo *info) {
+  CHECK(info->state == ConnectionInfo::State::Ready);
+  current_info_ = info;
+  info->wakeup_at = info->connection->flush(static_cast<mtproto::SessionConnection::Callback *>(this));
+}
+
+void Session::connection_close(ConnectionInfo *info) {
+  current_info_ = info;
+  if (info->state != ConnectionInfo::State::Ready) {
+    return;
+  }
+  info->connection->force_close(static_cast<mtproto::SessionConnection::Callback *>(this));
+  CHECK(info->state == ConnectionInfo::State::Empty);
+}
+
+bool Session::need_send_bind_key() {
+  return auth_data_.use_pfs() && !auth_data_.get_bind_flag() && auth_data_.get_tmp_auth_key().id() != tmp_auth_key_id_;
+}
+bool Session::need_send_query() {
+  return !close_flag_ && (!auth_data_.use_pfs() || auth_data_.get_bind_flag()) && !pending_queries_.empty();
+}
+bool Session::connection_send_bind_key(ConnectionInfo *info) {
+  CHECK(info->state != ConnectionInfo::State::Empty);
+  uint64 key_id = auth_data_.get_tmp_auth_key().id();
+  if (key_id == tmp_auth_key_id_) {
+    return false;
+  }
+  tmp_auth_key_id_ = key_id;
+  last_bind_id_ = UniqueId::next(UniqueId::BindKey);
+
+  int64 perm_auth_key_id = auth_data_.get_main_auth_key().id();
+  int64 nonce = Random::secure_int64();
+  int32 expire_at = static_cast<int32>(auth_data_.get_server_time(auth_data_.get_tmp_auth_key().expire_at()));
+  int64 message_id;
+  BufferSlice encrypted;
+  std::tie(message_id, encrypted) = info->connection->encrypted_bind(perm_auth_key_id, nonce, expire_at);
+
+  LOG(INFO) << "Bind key: " << tag("tmp", key_id) << tag("perm", static_cast<uint64>(perm_auth_key_id));
+  NetQueryPtr query = G()->net_query_creator().create(
+      last_bind_id_,
+      create_storer(telegram_api::auth_bindTempAuthKey(perm_auth_key_id, nonce, expire_at, std::move(encrypted))));
+  query->dispatch_ttl = 0;
+  query->set_callback(actor_shared(this));
+  connection_send_query(info, std::move(query), message_id);
+
+  return true;
+}
+
+void Session::on_handshake_ready(Result<std::unique_ptr<mtproto::AuthKeyHandshake>> r_handshake) {
+  auto handshake_id = narrow_cast<HandshakeId>(get_link_token() - 1);
+  bool is_main = handshake_id == MainAuthKeyHandshake;
+  auto &info = handshake_info_[handshake_id];
+  info.flag_ = false;
+  info.actor_.reset();
+
+  if (r_handshake.is_error()) {
+    LOG(ERROR) << "Handshake failed: " << r_handshake.move_as_error();
+  } else {
+    auto handshake = r_handshake.move_as_ok();
+    if (!handshake->is_ready_for_finish()) {
+      LOG(WARNING) << "Handshake is not yet ready";
+      info.handshake_ = std::move(handshake);
+    } else {
+      if (is_main) {
+        auth_data_.set_main_auth_key(std::move(handshake->auth_key));
+        on_auth_key_updated();
+      } else {
+        if (is_main_) {
+          registered_temp_auth_key_ = TempAuthKeyWatchdog::register_auth_key_id(handshake->auth_key.id());
+        }
+        auth_data_.set_tmp_auth_key(std::move(handshake->auth_key));
+        on_tmp_auth_key_updated();
+      }
+      LOG(WARNING) << "Update auth key in session_id " << auth_data_.session_id_ << " to "
+                   << auth_data_.get_auth_key().id();
+      connection_close(&main_connection_);
+      connection_close(&long_poll_connection_);
+
+      // Salt of temporary key is different salt. Do not rewrite it
+      if (auth_data_.use_pfs() ^ is_main) {
+        auth_data_.set_server_salt(handshake->server_salt, Time::now_cached());
+        on_server_salt_updated();
+      }
+      if (auth_data_.update_server_time_difference(handshake->server_time_diff)) {
+        on_server_time_difference_updated();
+      }
+      LOG(INFO) << "Got " << (is_main ? "main" : "tmp") << " auth key";
+    }
+  }
+
+  loop();
+}
+
+void Session::create_gen_auth_key_actor(HandshakeId handshake_id) {
+  auto &info = handshake_info_[handshake_id];
+  if (info.flag_) {
+    return;
+  }
+  LOG(INFO) << "Create GenAuthKeyActor " << handshake_id;
+  info.flag_ = true;
+  bool is_main = handshake_id == MainAuthKeyHandshake;
+  if (!info.handshake_) {
+    info.handshake_ = std::make_unique<mtproto::AuthKeyHandshake>(is_main && !is_cdn_ ? 0 : 24 * 60 * 60);
+  }
+  class AuthKeyHandshakeContext : public mtproto::AuthKeyHandshakeContext {
+   public:
+    AuthKeyHandshakeContext(DhCallback *dh_callback, std::shared_ptr<PublicRsaKeyInterface> public_rsa_key)
+        : dh_callback_(dh_callback), public_rsa_key_(std::move(public_rsa_key)) {
+    }
+    DhCallback *get_dh_callback() override {
+      return dh_callback_;
+    }
+    PublicRsaKeyInterface *get_public_rsa_key_interface() override {
+      return public_rsa_key_.get();
+    }
+
+   private:
+    DhCallback *dh_callback_;
+    std::shared_ptr<PublicRsaKeyInterface> public_rsa_key_;
+  };
+  info.actor_ = create_actor<detail::GenAuthKeyActor>(
+      "GenAuthKey", std::move(info.handshake_),
+      std::make_unique<AuthKeyHandshakeContext>(DhCache::instance(), shared_auth_data_->public_rsa_key()),
+      PromiseCreator::lambda([self = actor_id(this)](Result<std::unique_ptr<mtproto::RawConnection>> r_connection) {
+        if (r_connection.is_error() && r_connection.error().code() != 1) {
+          LOG(WARNING) << r_connection.error();
+          return;
+        }
+        send_closure(self, &Session::connection_add, r_connection.move_as_ok());
+      }),
+      PromiseCreator::lambda(
+          [self = actor_shared(this, handshake_id + 1), handshake_perf = PerfWarningTimer("handshake", 1000.1)](
+              Result<std::unique_ptr<mtproto::AuthKeyHandshake>> handshake) mutable {
+            // later is just to avoid lost hangup
+            send_closure_later(std::move(self), &Session::on_handshake_ready, std::move(handshake));
+          }),
+      callback_);
+}
+
+void Session::auth_loop() {
+  if (auth_data_.need_main_auth_key()) {
+    create_gen_auth_key_actor(MainAuthKeyHandshake);
+  }
+  if (auth_data_.need_tmp_auth_key(Time::now_cached())) {
+    create_gen_auth_key_actor(TmpAuthKeyHandshake);
+  }
+}
+
+void Session::loop() {
+  if (!was_on_network_) {
+    return;
+  }
+  Time::now();  // update now
+
+  if (cached_connection_timestamp_ < Time::now_cached() - 10) {
+    cached_connection_.reset();
+  }
+  if (!is_main_ && !has_queries() && last_activity_timestamp_ < Time::now_cached() - ACTIVITY_TIMEOUT) {
+    on_session_failed(Status::OK());
+  }
+
+  auth_loop();
+  connection_online_update();
+
+  double wakeup_at = 0;
+  main_connection_.wakeup_at = 0;
+  long_poll_connection_.wakeup_at = 0;
+
+  auth_lost_flag_ = false;
+  // NB: order is crucial. First long_poll_connection, then main_connection
+  // Otherwise queries could be sent with big delay
+
+  connection_check_mode(&main_connection_);
+  connection_check_mode(&long_poll_connection_);
+  if (mode_ == Mode::Http) {
+    if (long_poll_connection_.state == ConnectionInfo::State::Ready) {
+      connection_flush(&long_poll_connection_);
+    }
+    if (!close_flag_ && long_poll_connection_.state == ConnectionInfo::State::Empty) {
+      connection_open(&long_poll_connection_);
+    }
+    relax_timeout_at(&wakeup_at, long_poll_connection_.wakeup_at);
+  }
+
+  if (main_connection_.state == ConnectionInfo::State::Ready) {
+    // do not send queries before we have key and e.t.c
+    // do not send queries before tmp_key is bound
+    bool need_flush = true;
+    while (main_connection_.state == ConnectionInfo::State::Ready) {
+      if (auth_data_.is_ready(Time::now_cached())) {
+        if (need_send_query()) {
+          while (!pending_queries_.empty()) {
+            auto &query = pending_queries_.front();
+            connection_send_query(&main_connection_, std::move(query));
+            pending_queries_.pop_front();
+          }
+          need_flush = true;
+        }
+        if (need_send_bind_key()) {
+          // send auth.bindTempAuthKey
+          connection_send_bind_key(&main_connection_);
+          need_flush = true;
+        }
+      }
+      if (need_flush) {
+        connection_flush(&main_connection_);
+        need_flush = false;
+      } else {
+        break;
+      }
+    }
+  }
+  if (!close_flag_ && main_connection_.state == ConnectionInfo::State::Empty) {
+    connection_open(&main_connection_, true /*send ask_info*/);
+  }
+
+  if (auth_lost_flag_) {
+    connection_close(&main_connection_);
+    connection_close(&long_poll_connection_);
+    auth_lost_flag_ = false;
+    relax_timeout_at(&wakeup_at, Time::now_cached() + 0.1);
+  }
+
+  relax_timeout_at(&wakeup_at, main_connection_.wakeup_at);
+
+  double wakeup_in = 0;
+  if (wakeup_at != 0) {
+    wakeup_in = wakeup_at - Time::now_cached();
+    LOG(INFO) << "Wakeup After " << wakeup_in;
+    set_timeout_at(wakeup_at);
+  }
+  // TODO: write proper condition..
+  // LOG_IF(ERROR, !close_flag_ && ((wakeup_at == 0 && network_flag_) || wakeup_in < 0 || wakeup_in > 3000))
+  // << "Bad timeout in: " << wakeup_in;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/Session.h b/libs/tdlib/td/td/telegram/net/Session.h
new file mode 100644
index 0000000000..93f69a27b4
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/Session.h
@@ -0,0 +1,235 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/mtproto/AuthData.h"
+#include "td/mtproto/Handshake.h"
+#include "td/mtproto/SessionConnection.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/net/AuthDataShared.h"
+#include "td/telegram/net/NetQuery.h"
+#include "td/telegram/net/TempAuthKeyWatchdog.h"
+#include "td/telegram/StateManager.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/List.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+
+#include <array>
+#include <deque>
+#include <map>
+#include <memory>
+#include <unordered_map>
+#include <unordered_set>
+#include <utility>
+
+namespace td {
+
+namespace mtproto {
+class RawConnection;
+}  // namespace mtproto
+
+namespace detail {
+class GenAuthKeyActor;
+}  // namespace detail
+
+class Session final
+    : public NetQueryCallback
+    , private mtproto::SessionConnection::Callback {
+ public:
+  class Callback {
+   public:
+    Callback() = default;
+    Callback(const Callback &) = delete;
+    Callback &operator=(const Callback &) = delete;
+    virtual ~Callback() = default;
+    virtual void on_failed() = 0;
+    virtual void on_closed() = 0;
+    virtual void request_raw_connection(Promise<std::unique_ptr<mtproto::RawConnection>>) = 0;
+    virtual void on_tmp_auth_key_updated(mtproto::AuthKey auth_key) = 0;
+    // one still have to call close after on_closed
+  };
+
+  Session(unique_ptr<Callback> callback, std::shared_ptr<AuthDataShared> shared_auth_data, bool is_main, bool use_pfs,
+          bool is_cdn, const mtproto::AuthKey &tmp_auth_key);
+  void send(NetQueryPtr &&query);
+  void on_network(bool network_flag, uint32 network_generation);
+  void on_online(bool online_flag);
+  void close();
+
+ private:
+  struct Query : private ListNode {
+    uint64 container_id;
+    NetQueryPtr query;
+
+    bool ack = false;
+    bool unknown = false;
+
+    int8 connection_id;
+    double sent_at_;
+    Query(uint64 message_id, NetQueryPtr &&q, int8 connection_id, double sent_at)
+        : container_id(message_id), query(std::move(q)), connection_id(connection_id), sent_at_(sent_at) {
+    }
+
+    ListNode *get_list_node() {
+      return static_cast<ListNode *>(this);
+    }
+    static Query *from_list_node(ListNode *list_node) {
+      return static_cast<Query *>(list_node);
+    }
+  };
+
+  // When connection is closed, mark all queries without ack as unknown
+  // Ask state of all unknown queries when new connection is created.
+  //
+  // Just re-ask answer_id each time we get information about it.
+  // Thought mtproto::Connection must ensure delivery of such query
+
+  enum class Mode { Tcp, Http } mode_ = Mode::Tcp;
+  bool is_main_;
+  bool is_cdn_;
+  bool was_on_network_ = false;
+  bool network_flag_ = false;
+  uint32 network_generation_ = 0;
+  bool online_flag_ = false;
+  bool connection_online_flag_ = false;
+  uint64 tmp_auth_key_id_ = 0;
+  uint64 last_bind_id_ = 0;
+  double last_activity_timestamp_ = 0;
+  size_t dropped_size_ = 0;
+
+  std::unordered_set<uint64> unknown_queries_;
+  std::vector<int64> to_cancel_;
+
+  // Do not invalidate iterators of this two containers!
+  // TODO: better data structures
+  std::deque<NetQueryPtr> pending_queries_;
+  std::map<uint64, Query> sent_queries_;
+  std::deque<NetQueryPtr> pending_invoke_after_queries_;
+  ListNode sent_queries_list_;
+
+  struct ConnectionInfo {
+    int8 connection_id;
+    Mode mode;
+    enum class State { Empty, Connecting, Ready } state = State::Empty;
+    mtproto::AuthKeyHandshake handshake;
+    mtproto::AuthKeyHandshake tmp_handshake;
+    unique_ptr<mtproto::SessionConnection> connection;
+    bool ask_info;
+    double wakeup_at = 0;
+    double created_at_ = 0;
+  };
+
+  ConnectionInfo *current_info_;
+  ConnectionInfo main_connection_;
+  ConnectionInfo long_poll_connection_;
+  bool auth_lost_flag_ = false;
+  StateManager::ConnectionToken connection_token_;
+
+  double cached_connection_timestamp_ = 0;
+  std::unique_ptr<mtproto::RawConnection> cached_connection_;
+
+  std::shared_ptr<Callback> callback_;
+  mtproto::AuthData auth_data_;
+  TempAuthKeyWatchdog::RegisteredAuthKey registered_temp_auth_key_;
+  std::shared_ptr<AuthDataShared> shared_auth_data_;
+  bool close_flag_ = false;
+
+  static constexpr double ACTIVITY_TIMEOUT = 60 * 5;
+
+  struct ContainerInfo {
+    size_t ref_cnt;
+    std::vector<uint64> message_ids;
+  };
+  std::unordered_map<uint64, ContainerInfo> sent_containers_;
+
+  friend class GenAuthKeyActor;
+  struct HandshakeInfo {
+    bool flag_ = false;
+    ActorOwn<detail::GenAuthKeyActor> actor_;
+    std::unique_ptr<mtproto::AuthKeyHandshake> handshake_;
+  };
+  enum HandshakeId : int32 { MainAuthKeyHandshake = 0, TmpAuthKeyHandshake = 1 };
+  std::array<HandshakeInfo, 2> handshake_info_;
+
+  double wakeup_at_;
+  void on_handshake_ready(Result<std::unique_ptr<mtproto::AuthKeyHandshake>> r_handshake);
+  void create_gen_auth_key_actor(HandshakeId handshake_id);
+  void auth_loop();
+
+  // mtproto::Connection::Callback
+  void on_connected() override;
+  void on_before_close() override;
+  void on_closed(Status status) override;
+
+  Status on_pong() override;
+
+  void on_auth_key_updated() override;
+  void on_tmp_auth_key_updated() override;
+  void on_server_salt_updated() override;
+  void on_server_time_difference_updated() override;
+
+  void on_session_created(uint64 unique_id, uint64 first_id) override;
+  void on_session_failed(Status status) override;
+
+  void on_container_sent(uint64 container_id, vector<uint64> msg_ids) override;
+
+  void on_message_ack(uint64 id) override;
+  Status on_message_result_ok(uint64 id, BufferSlice packet, size_t original_size) override;
+  void on_message_result_error(uint64 id, int error_code, BufferSlice message) override;
+  void on_message_failed(uint64 id, Status status) override;
+
+  void on_message_info(uint64 id, int32 state, uint64 answer_id, int32 answer_size) override;
+
+  void flush_pending_invoke_after_queries();
+  bool has_queries() const;
+
+  void dec_container(uint64 message_id, Query *query);
+  void cleanup_container(uint64 id, Query *query);
+  void mark_as_known(uint64 id, Query *query);
+  void mark_as_unknown(uint64 id, Query *query);
+
+  void on_message_ack_impl(uint64 id, int32 type);
+  void on_message_ack_impl_inner(uint64 id, int32 type, bool in_container);
+  void on_message_failed_inner(uint64 id, bool in_container);
+
+  // send NetQueryPtr to parent
+  void return_query(NetQueryPtr &&query);
+  void add_query(NetQueryPtr &&net_query);
+  void resend_query(NetQueryPtr query);
+
+  void connection_open(ConnectionInfo *info, bool ask_info = false);
+  void connection_add(std::unique_ptr<mtproto::RawConnection> raw_connection);
+  void connection_check_mode(ConnectionInfo *info);
+  void connection_open_finish(ConnectionInfo *info, Result<std::unique_ptr<mtproto::RawConnection>> r_raw_connection);
+
+  void connection_online_update(bool force = false);
+  void connection_close(ConnectionInfo *info);
+  void connection_flush(ConnectionInfo *info);
+  void connection_send_query(ConnectionInfo *info, NetQueryPtr &&net_query, uint64 message_id = 0);
+  bool need_send_bind_key();
+  bool need_send_query();
+  bool connection_send_bind_key(ConnectionInfo *info);
+
+  void on_result(NetQueryPtr query) override;
+
+  void start_up() override;
+  void loop() override;
+  void hangup() override;
+  void raw_event(const Event::Raw &event) override;
+
+  friend StringBuilder &operator<<(StringBuilder &sb, Mode mode) {
+    return sb << (mode == Mode::Http ? "Http" : "Tcp");
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/SessionMultiProxy.cpp b/libs/tdlib/td/td/telegram/net/SessionMultiProxy.cpp
new file mode 100644
index 0000000000..7fe27dd81e
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/SessionMultiProxy.cpp
@@ -0,0 +1,111 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/SessionMultiProxy.h"
+
+#include "td/telegram/net/SessionProxy.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+
+namespace td {
+
+SessionMultiProxy::SessionMultiProxy() = default;
+SessionMultiProxy::~SessionMultiProxy() = default;
+
+SessionMultiProxy::SessionMultiProxy(int32 session_count, std::shared_ptr<AuthDataShared> shared_auth_data,
+                                     bool is_main, bool use_pfs, bool allow_media_only, bool is_media, bool is_cdn)
+    : session_count_(session_count)
+    , auth_data_(std::move(shared_auth_data))
+    , is_main_(is_main)
+    , use_pfs_(use_pfs)
+    , allow_media_only_(allow_media_only)
+    , is_media_(is_media)
+    , is_cdn_(is_cdn) {
+  if (allow_media_only_) {
+    CHECK(is_media_);
+  }
+}
+
+void SessionMultiProxy::send(NetQueryPtr query) {
+  size_t pos = 0;
+  // TODO temporary hack with total_timeout_limit
+  if (query->auth_flag() == NetQuery::AuthFlag::On && query->total_timeout_limit > 50) {
+    if (query->session_rand()) {
+      pos = query->session_rand() % sessions_.size();
+    } else {
+      pos = pos_++ % sessions_.size();
+    }
+  }
+  query->debug(PSTRING() << get_name() << ": send to proxy #" << pos);
+  send_closure(sessions_[pos], &SessionProxy::send, std::move(query));
+}
+
+void SessionMultiProxy::update_main_flag(bool is_main) {
+  LOG(INFO) << "Update " << get_name() << " is_main to " << is_main;
+  is_main_ = is_main;
+  for (auto &session : sessions_) {
+    send_closure(session, &SessionProxy::update_main_flag, is_main);
+  }
+}
+void SessionMultiProxy::update_session_count(int32 session_count) {
+  update_options(session_count, use_pfs_);
+}
+void SessionMultiProxy::update_use_pfs(bool use_pfs) {
+  update_options(session_count_, use_pfs);
+}
+
+void SessionMultiProxy::update_options(int32 session_count, bool use_pfs) {
+  bool changed = false;
+
+  if (session_count != session_count_) {
+    session_count_ = session_count;
+    if (session_count_ <= 0) {
+      session_count_ = 1;
+    }
+    if (session_count_ > 100) {
+      session_count_ = 100;
+    }
+    LOG(INFO) << "Update " << get_name() << " session_count to " << session_count_;
+    changed = true;
+  }
+
+  if (use_pfs != use_pfs_) {
+    bool old_pfs_flag = get_pfs_flag();
+    use_pfs_ = use_pfs;
+    if (old_pfs_flag != get_pfs_flag()) {
+      LOG(INFO) << "Update " << get_name() << " use_pfs to " << use_pfs_;
+      changed = true;
+    }
+  }
+  if (changed) {
+    init();
+  }
+}
+
+void SessionMultiProxy::start_up() {
+  init();
+}
+
+bool SessionMultiProxy::get_pfs_flag() const {
+  return (!allow_media_only_ && use_pfs_);  // pfs is not supported in media only DCs
+}
+
+void SessionMultiProxy::init() {
+  sessions_.clear();
+  if (is_main_) {
+    LOG(WARNING) << tag("session_count", session_count_);
+  }
+  for (int32 i = 0; i < session_count_; i++) {
+    string name = PSTRING() << "Session" << get_name().substr(Slice("SessionMulti").size())
+                            << format::cond(session_count_ > 1, format::concat("#", i));
+    sessions_.push_back(create_actor<SessionProxy>(name, auth_data_, is_main_, allow_media_only_, is_media_,
+                                                   get_pfs_flag(), is_main_ && i != 0, is_cdn_));
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/SessionMultiProxy.h b/libs/tdlib/td/td/telegram/net/SessionMultiProxy.h
new file mode 100644
index 0000000000..7a31656cf6
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/SessionMultiProxy.h
@@ -0,0 +1,53 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/telegram/net/AuthDataShared.h"
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/actor/actor.h"
+
+#include <memory>
+
+namespace td {
+class SessionProxy;
+
+class SessionMultiProxy : public Actor {
+ public:
+  SessionMultiProxy();
+  SessionMultiProxy(const SessionMultiProxy &other) = delete;
+  SessionMultiProxy &operator=(const SessionMultiProxy &other) = delete;
+  ~SessionMultiProxy() override;
+  SessionMultiProxy(int32 session_count, std::shared_ptr<AuthDataShared> shared_auth_data, bool is_main, bool use_pfs,
+                    bool allow_media_only, bool is_media, bool is_cdn);
+
+  void send(NetQueryPtr query);
+  void update_main_flag(bool is_main);
+
+  void update_session_count(int32 session_count);
+  void update_use_pfs(bool use_pfs);
+  void update_options(int32 session_count, bool use_pfs);
+
+ private:
+  size_t pos_ = 0;
+  int32 session_count_ = 0;
+  std::shared_ptr<AuthDataShared> auth_data_;
+  bool is_main_ = false;
+  bool use_pfs_ = false;
+  bool allow_media_only_ = false;
+  bool is_media_ = false;
+  bool is_cdn_ = false;
+  std::vector<ActorOwn<SessionProxy>> sessions_;
+
+  void start_up() override;
+  void init();
+
+  bool get_pfs_flag() const;
+
+  void update_auth_state();
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/SessionProxy.cpp b/libs/tdlib/td/td/telegram/net/SessionProxy.cpp
new file mode 100644
index 0000000000..df1e1d84f8
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/SessionProxy.cpp
@@ -0,0 +1,182 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/net/SessionProxy.h"
+
+#include "td/telegram/Global.h"
+#include "td/telegram/net/ConnectionCreator.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+#include "td/telegram/net/Session.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+
+#include <functional>
+
+namespace td {
+namespace mtproto {
+class RawConnection;
+}  // namespace mtproto
+
+class SessionCallback : public Session::Callback {
+ public:
+  SessionCallback(ActorShared<SessionProxy> parent, DcId dc_id, bool allow_media_only, bool is_media, size_t hash)
+      : parent_(std::move(parent))
+      , dc_id_(dc_id)
+      , allow_media_only_(allow_media_only)
+      , is_media_(is_media)
+      , hash_(hash) {
+  }
+
+  void on_failed() override {
+    send_closure(parent_, &SessionProxy::on_failed);
+  }
+  void on_closed() override {
+    send_closure(parent_, &SessionProxy::on_closed);
+  }
+  void request_raw_connection(Promise<std::unique_ptr<mtproto::RawConnection>> promise) override {
+    send_closure(G()->connection_creator(), &ConnectionCreator::request_raw_connection, dc_id_, allow_media_only_,
+                 is_media_, std::move(promise), hash_);
+  }
+
+  void on_tmp_auth_key_updated(mtproto::AuthKey auth_key) override {
+    send_closure(parent_, &SessionProxy::on_tmp_auth_key_updated, std::move(auth_key));
+  }
+
+ private:
+  ActorShared<SessionProxy> parent_;
+  DcId dc_id_;
+  bool allow_media_only_ = false;
+  bool is_media_ = false;
+  size_t hash_ = 0;
+};
+
+SessionProxy::SessionProxy(std::shared_ptr<AuthDataShared> shared_auth_data, bool is_main, bool allow_media_only,
+                           bool is_media, bool use_pfs, bool need_wait_for_key, bool is_cdn)
+    : auth_data_(std::move(shared_auth_data))
+    , is_main_(is_main)
+    , allow_media_only_(allow_media_only)
+    , is_media_(is_media)
+    , use_pfs_(use_pfs)
+    , need_wait_for_key_(need_wait_for_key)
+    , is_cdn_(is_cdn) {
+}
+
+void SessionProxy::start_up() {
+  class Listener : public AuthDataShared::Listener {
+   public:
+    explicit Listener(ActorShared<SessionProxy> session_proxy) : session_proxy_(std::move(session_proxy)) {
+    }
+    bool notify() override {
+      if (!session_proxy_.is_alive()) {
+        return false;
+      }
+      send_closure(session_proxy_, &SessionProxy::update_auth_state);
+      return true;
+    }
+
+   private:
+    ActorShared<SessionProxy> session_proxy_;
+  };
+  auth_state_ = auth_data_->get_auth_state().first;
+  auth_data_->add_auth_key_listener(std::make_unique<Listener>(actor_shared(this)));
+  if (is_main_ && !need_wait_for_key_) {
+    open_session();
+  }
+}
+
+void SessionProxy::tear_down() {
+  for (auto &query : pending_queries_) {
+    query->resend();
+    G()->net_query_dispatcher().dispatch(std::move(query));
+  }
+  pending_queries_.clear();
+}
+
+void SessionProxy::send(NetQueryPtr query) {
+  if (query->auth_flag() == NetQuery::AuthFlag::On && auth_state_ != AuthState::OK) {
+    query->debug(PSTRING() << get_name() << ": wait for auth");
+    pending_queries_.emplace_back(std::move(query));
+    return;
+  }
+  if (session_.empty()) {
+    open_session(true);
+  }
+  query->debug(PSTRING() << get_name() << ": sent to session");
+  send_closure(session_, &Session::send, std::move(query));
+}
+
+void SessionProxy::update_main_flag(bool is_main) {
+  if (is_main_ == is_main) {
+    return;
+  }
+  LOG(INFO) << "Update " << get_name() << " is_main to " << is_main;
+  is_main_ = is_main;
+  close_session();
+  open_session();
+}
+
+void SessionProxy::on_failed() {
+  if (session_generation_ != get_link_token()) {
+    return;
+  }
+  close_session();
+  open_session();
+}
+
+void SessionProxy::on_closed() {
+}
+
+void SessionProxy::close_session() {
+  send_closure(std::move(session_), &Session::close);
+  session_generation_++;
+}
+void SessionProxy::open_session(bool force) {
+  if (!force && !is_main_) {
+    return;
+  }
+  CHECK(session_.empty());
+  string name = PSTRING() << "Session" << get_name().substr(Slice("SessionProxy").size());
+  string hash_string = PSTRING() << name << " " << auth_data_->dc_id().get_raw_id() << " " << allow_media_only_;
+  auto hash = std::hash<std::string>()(hash_string);
+  session_ =
+      create_actor<Session>(name,
+                            make_unique<SessionCallback>(actor_shared(this, session_generation_), auth_data_->dc_id(),
+                                                         allow_media_only_, is_media_, hash),
+                            auth_data_, is_main_, use_pfs_, is_cdn_, tmp_auth_key_);
+}
+
+void SessionProxy::update_auth_state() {
+  auth_state_ = auth_data_->get_auth_state().first;
+  if (pending_queries_.empty() && !need_wait_for_key_) {
+    return;
+  }
+  if (auth_state_ != AuthState::OK) {
+    return;
+  }
+  if (session_.empty()) {
+    open_session(true);
+  }
+  for (auto &query : pending_queries_) {
+    query->debug(PSTRING() << get_name() << ": sent to session");
+    send_closure(session_, &Session::send, std::move(query));
+  }
+  pending_queries_.clear();
+}
+
+void SessionProxy::on_tmp_auth_key_updated(mtproto::AuthKey auth_key) {
+  string state;
+  if (auth_key.empty()) {
+    state = "Empty";
+  } else if (auth_key.auth_flag()) {
+    state = "OK";
+  } else {
+    state = "NoAuth";
+  }
+  LOG(WARNING) << "tmp_auth_key " << auth_key.id() << ": " << state;
+  tmp_auth_key_ = std::move(auth_key);
+}
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/SessionProxy.h b/libs/tdlib/td/td/telegram/net/SessionProxy.h
new file mode 100644
index 0000000000..40f881612d
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/SessionProxy.h
@@ -0,0 +1,52 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/telegram/net/AuthDataShared.h"
+#include "td/telegram/net/NetQuery.h"
+
+#include "td/actor/actor.h"
+
+#include <memory>
+
+namespace td {
+class Session;
+class SessionProxy : public Actor {
+ public:
+  friend class SessionCallback;
+
+  SessionProxy(std::shared_ptr<AuthDataShared> shared_auth_data, bool is_main, bool allow_media_only, bool is_media,
+               bool use_pfs, bool need_wait_for_key, bool is_cdn);
+
+  void send(NetQueryPtr query);
+  void update_main_flag(bool is_main);
+
+ private:
+  std::shared_ptr<AuthDataShared> auth_data_;
+  AuthState auth_state_;
+  bool is_main_;
+  bool allow_media_only_;
+  bool is_media_;
+  bool use_pfs_;
+  mtproto::AuthKey tmp_auth_key_;
+  bool need_wait_for_key_;
+  bool is_cdn_;
+  ActorOwn<Session> session_;
+  std::vector<NetQueryPtr> pending_queries_;
+  uint64 session_generation_ = 1;
+
+  void on_failed();
+  void on_closed();
+  void close_session();
+  void open_session(bool force = false);
+
+  void update_auth_state();
+  void on_tmp_auth_key_updated(mtproto::AuthKey auth_key);
+
+  void start_up() override;
+  void tear_down() override;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/net/TempAuthKeyWatchdog.h b/libs/tdlib/td/td/telegram/net/TempAuthKeyWatchdog.h
new file mode 100644
index 0000000000..eff190bf61
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/net/TempAuthKeyWatchdog.h
@@ -0,0 +1,127 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+
+#include "td/telegram/Global.h"
+#include "td/telegram/net/NetQueryCreator.h"
+#include "td/telegram/net/NetQueryDispatcher.h"
+
+#include "td/telegram/telegram_api.h"
+
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/Time.h"
+
+#include <map>
+
+namespace td {
+class TempAuthKeyWatchdog : public NetQueryCallback {
+  class RegisteredAuthKeyImpl {
+   public:
+    explicit RegisteredAuthKeyImpl(int64 auth_key_id)
+        : watchdog_(G()->temp_auth_key_watchdog()), auth_key_id_(auth_key_id) {
+    }
+    RegisteredAuthKeyImpl(const RegisteredAuthKeyImpl &other) = delete;
+    RegisteredAuthKeyImpl &operator=(const RegisteredAuthKeyImpl &other) = delete;
+    RegisteredAuthKeyImpl(RegisteredAuthKeyImpl &&other) = delete;
+    RegisteredAuthKeyImpl &operator=(RegisteredAuthKeyImpl &&other) = delete;
+    ~RegisteredAuthKeyImpl() {
+      send_closure(watchdog_, &TempAuthKeyWatchdog::unregister_auth_key_id_impl, auth_key_id_);
+    }
+
+   private:
+    ActorId<TempAuthKeyWatchdog> watchdog_;
+    int64 auth_key_id_;
+  };
+
+ public:
+  using RegisteredAuthKey = std::unique_ptr<RegisteredAuthKeyImpl>;
+
+  static RegisteredAuthKey register_auth_key_id(int64 id) {
+    send_closure(G()->temp_auth_key_watchdog(), &TempAuthKeyWatchdog::register_auth_key_id_impl, id);
+    return std::make_unique<RegisteredAuthKeyImpl>(id);
+  }
+
+ private:
+  static constexpr double SYNC_WAIT = 0.1;
+  static constexpr double SYNC_WAIT_MAX = 1.0;
+
+  std::map<uint64, uint32> id_count_;
+  double sync_at_ = 0;
+  bool need_sync_ = false;
+  bool run_sync_ = false;
+
+  void register_auth_key_id_impl(int64 id) {
+    if (!++id_count_[id]) {
+      id_count_.erase(id);
+    }
+    need_sync();
+  }
+
+  void unregister_auth_key_id_impl(int64 id) {
+    if (!--id_count_[id]) {
+      id_count_.erase(id);
+    }
+    need_sync();
+  }
+
+  void need_sync() {
+    need_sync_ = true;
+    try_sync();
+    LOG(DEBUG) << "need sync";
+  }
+
+  void try_sync() {
+    if (run_sync_ || !need_sync_) {
+      return;
+    }
+
+    auto now = Time::now();
+    if (sync_at_ == 0) {
+      sync_at_ = now + SYNC_WAIT_MAX;
+    }
+    LOG(DEBUG) << "set timeout";
+    set_timeout_at(min(sync_at_, now + SYNC_WAIT));
+  }
+
+  void timeout_expired() override {
+    LOG(DEBUG) << "timeout expired";
+    CHECK(!run_sync_);
+    if (!need_sync_) {
+      LOG(ERROR) << "Do not need sync..";
+      return;
+    }
+    need_sync_ = false;
+    run_sync_ = true;
+    sync_at_ = 0;
+    vector<int64> ids;
+    for (auto &id_count : id_count_) {
+      ids.push_back(id_count.first);
+    }
+    if (G()->close_flag()) {
+      return;
+    }
+    LOG(WARNING) << "Start auth_dropTempAuthKeys except keys " << format::as_array(ids);
+    auto query = G()->net_query_creator().create(create_storer(telegram_api::auth_dropTempAuthKeys(std::move(ids))));
+    G()->net_query_dispatcher().dispatch_with_callback(std::move(query), actor_shared(this));
+  }
+
+  void on_result(NetQueryPtr query) final {
+    run_sync_ = false;
+    if (query->is_error()) {
+      LOG(ERROR) << "auth_dropTempAuthKeys failed " << query->error();
+      need_sync_ = true;
+    } else {
+      LOG(INFO) << "auth_dropTempAuthKeys OK";
+    }
+    try_sync();
+  }
+};
+}  // namespace td
diff --git a/libs/tdlib/td/td/telegram/td_c_client.cpp b/libs/tdlib/td/td/telegram/td_c_client.cpp
new file mode 100644
index 0000000000..da3061199d
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/td_c_client.cpp
@@ -0,0 +1,80 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/td_c_client.h"
+
+#include "td/telegram/Client.h"
+#include "td/telegram/Log.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/td_tdc_api_inner.h"
+
+#include <cstring>
+
+void *TdCClientCreate() {
+  return new td::Client();
+}
+
+void TdCClientSend(void *instance, struct TdRequest request) {
+  auto client = static_cast<td::Client *>(instance);
+  td::Client::Request client_request;
+  client_request.id = request.id;
+  client_request.function = TdConvertToInternal(request.function);
+  TdDestroyObjectFunction(request.function);
+  client->send(std::move(client_request));
+}
+
+TdResponse TdCClientReceive(void *instance, double timeout) {
+  auto client = static_cast<td::Client *>(instance);
+  auto response = client->receive(timeout);
+  TdResponse c_response;
+  c_response.id = response.id;
+  c_response.object = response.object == nullptr
+                          ? nullptr
+                          : TdConvertFromInternal(static_cast<const td::td_api::Object &>(*response.object));
+  return c_response;
+}
+
+void TdCClientDestroy(void *instance) {
+  auto client = static_cast<td::Client *>(instance);
+  delete client;
+}
+
+void TdCClientSetVerbosity(int new_verbosity_level) {
+  td::Log::set_verbosity_level(new_verbosity_level);
+}
+
+TdVectorInt *TdCreateObjectVectorInt(int size, int *data) {
+  auto res = new TdVectorInt();
+  res->len = size;
+  res->data = new int[size];
+  std::memcpy(res->data, data, sizeof(int) * size);
+  return res;
+}
+
+TdVectorLong *TdCreateObjectVectorLong(int size, long long *data) {
+  auto res = new TdVectorLong();
+  res->len = size;
+  res->data = new long long[size];
+  std::memcpy(res->data, data, sizeof(long long) * size);
+  return res;
+}
+
+TdVectorObject *TdCreateObjectVectorObject(int size, TdObject **data) {
+  auto res = new TdVectorObject();
+  res->len = size;
+  res->data = new TdObject *[size];
+  std::memcpy(res->data, data, sizeof(TdObject *) * size);
+  return res;
+}
+
+TdBytes TdCreateObjectBytes(unsigned char *data, int len) {
+  TdBytes res;
+  res.len = len;
+  res.data = new unsigned char[len];
+  std::memcpy(res.data, data, len);
+  return res;
+}
diff --git a/libs/tdlib/td/td/telegram/td_c_client.h b/libs/tdlib/td/td/telegram/td_c_client.h
new file mode 100644
index 0000000000..fc472f9fdf
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/td_c_client.h
@@ -0,0 +1,39 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "td/telegram/td_tdc_api.h"
+
+struct TdVectorInt *TdCreateObjectVectorInt(int size, int *data);
+struct TdVectorLong *TdCreateObjectVectorLong(int size, long long *data);
+struct TdVectorObject *TdCreateObjectVectorObject(int size, struct TdObject **data);
+struct TdBytes TdCreateObjectBytes(unsigned char *data, int len);
+
+struct TdRequest {
+  long long id;
+  TdFunction *function;
+};
+
+struct TdResponse {
+  long long id;
+  TdObject *object;
+};
+
+void *TdCClientCreate();
+void TdCClientSend(void *instance, struct TdRequest cmd);
+struct TdResponse TdCClientSendCommandSync(void *instance, double timeout);
+void TdCClientDestroy(void *instance);
+
+void TdCClientSetVerbosity(int new_verbosity_level);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/libs/tdlib/td/td/telegram/td_emscripten.cpp b/libs/tdlib/td/td/telegram/td_emscripten.cpp
new file mode 100644
index 0000000000..ba9e31f7e9
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/td_emscripten.cpp
@@ -0,0 +1,40 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// Just for testing.
+// Will be completly rewritten
+
+#include "td/telegram/td_json_client.h"
+#include "td/telegram/td_log.h"
+
+#include <emscripten.h>
+
+extern "C" {
+
+EMSCRIPTEN_KEEPALIVE void *td_create() {
+  return td_json_client_create();
+}
+EMSCRIPTEN_KEEPALIVE void td_send(void *client, const char *query) {
+  td_json_client_send(client, query);
+}
+EMSCRIPTEN_KEEPALIVE const char *td_receive(void *client) {
+  return td_json_client_receive(client, 0);
+}
+EMSCRIPTEN_KEEPALIVE const char *td_execute(void *client, const char *query) {
+  return td_json_client_execute(client, query);
+}
+EMSCRIPTEN_KEEPALIVE void td_destroy(void *client) {
+  td_json_client_destroy(client);
+}
+EMSCRIPTEN_KEEPALIVE void td_set_verbosity(int verbosity) {
+  td_set_log_verbosity_level(verbosity);
+}
+}
+
+int main(void) {
+  emscripten_exit_with_live_runtime();
+  return 0;
+}
diff --git a/libs/tdlib/td/td/telegram/td_json_client.cpp b/libs/tdlib/td/td/telegram/td_json_client.cpp
new file mode 100644
index 0000000000..94f327d19e
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/td_json_client.cpp
@@ -0,0 +1,45 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/td_json_client.h"
+
+#include "td/telegram/ClientJson.h"
+
+#include "td/utils/Slice.h"
+
+extern "C" int td_json_client_square(int x, const char *str) {
+  return x * x;
+}
+
+void *td_json_client_create() {
+  return new td::ClientJson();
+}
+
+void td_json_client_destroy(void *client) {
+  delete static_cast<td::ClientJson *>(client);
+}
+
+void td_json_client_send(void *client, const char *request) {
+  static_cast<td::ClientJson *>(client)->send(td::Slice(request));
+}
+
+const char *td_json_client_receive(void *client, double timeout) {
+  auto slice = static_cast<td::ClientJson *>(client)->receive(timeout);
+  if (slice.empty()) {
+    return nullptr;
+  } else {
+    return slice.c_str();
+  }
+}
+
+const char *td_json_client_execute(void *client, const char *request) {
+  auto slice = static_cast<td::ClientJson *>(client)->execute(td::Slice(request));
+  if (slice.empty()) {
+    return nullptr;
+  } else {
+    return slice.c_str();
+  }
+}
diff --git a/libs/tdlib/td/td/telegram/td_json_client.h b/libs/tdlib/td/td/telegram/td_json_client.h
new file mode 100644
index 0000000000..55a0f00837
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/td_json_client.h
@@ -0,0 +1,99 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+/**
+ * \file
+ * C interface for interaction with TDLib via JSON-serialized objects.
+ * Can be used to easily integrate TDLib with any programming language which supports calling C functions
+ * and is able to work with JSON.
+ *
+ * The JSON serialization of TDLib API objects is straightforward: all API objects are represented as JSON objects with
+ * the same keys as the API object field names. The object type name is stored in the special field "@type", which is
+ * optional in places where a type is uniquely determined by the context.
+ * Bool object fields are stored as Booleans in JSON. int32, int53 and double fields are stored as Numbers.
+ * int64 and string fields are stored as Strings. bytes fields are base64 encoded and then stored as String.
+ * vectors are stored as Arrays.
+ * The main TDLib interface is asynchronous. To match requests with a corresponding response a field "@extra" can
+ * be added to the request object. The corresponding response will have an "@extra" field with exactly the same value.
+ *
+ * A TDLib client instance should be created through td_json_client_create.
+ * Requests then can be sent using td_json_client_send from any thread.
+ * New updates and request responses can be received through td_json_client_receive from any thread. This function
+ * shouldn't be called simultaneously from two different threads. Also note that all updates and request responses
+ * should be applied in the order they were received to ensure consistency.
+ * Given this information, it's advisable to call this function from a dedicated thread.
+ * Some service TDLib requests can be executed synchronously from any thread by using td_json_client_execute.
+ * The TDLib client instance can be destroyed via td_json_client_destroy.
+ *
+ * General pattern of usage:
+ * \code
+ * void *client = td_json_client_create();
+ * // somehow share the client with other threads, which will be able to send requests via td_json_client_send
+ *
+ * const double WAIT_TIMEOUT = 10.0; // seconds
+ * int is_closed = 0;  // should be set to 1, when updateAuthorizationState with authorizationStateClosed is received
+ * while (!is_closed) {
+ *   const char *result = td_json_client_receive(client, WAIT_TIMEOUT);
+ *   if (result) {
+ *     // parse the result as JSON object and process it as an incoming update or an answer to a previously sent request
+ *   }
+ * }
+ * td_json_client_destroy(client);
+ * \endcode
+ */
+
+#include "td/telegram/tdjson_export.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Creates a new instance of TDLib.
+ * \return Pointer to the created instance of TDLib.
+ */
+TDJSON_EXPORT void *td_json_client_create();
+
+/**
+ * Sends request to the TDLib client. May be called from any thread.
+ * \param[in] client The client.
+ * \param[in] request JSON-serialized null-terminated request to TDLib.
+ */
+TDJSON_EXPORT void td_json_client_send(void *client, const char *request);
+
+/**
+ * Receives incoming updates and request responses from the TDLib client. May be called from any thread, but
+ * shouldn't be called simultaneously from two different threads.
+ * Returned pointer will be deallocated by TDLib during next call to td_json_client_receive or td_json_client_execute
+ * in the same thread, so it can't be used after that.
+ * \param[in] client The client.
+ * \param[in] timeout Maximum number of seconds allowed for this function to wait for new data.
+ * \return JSON-serialized null-terminated incoming update or request response. May be NULL if the timeout expires.
+ */
+TDJSON_EXPORT const char *td_json_client_receive(void *client, double timeout);
+
+/**
+ * Synchronously executes TDLib request. May be called from any thread.
+ * Only a few requests can be executed synchronously.
+ * Returned pointer will be deallocated by TDLib during next call to td_json_client_receive or td_json_client_execute
+ * in the same thread, so it can't be used after that.
+ * \param[in] client The client.
+ * \param[in] request JSON-serialized null-terminated request to TDLib.
+ * \return JSON-serialized null-terminated request response. May be NULL if the request can't be parsed.
+ */
+TDJSON_EXPORT const char *td_json_client_execute(void *client, const char *request);
+
+/**
+ * Destroys the TDLib client instance. After this is called the client instance shouldn't be used anymore.
+ * \param[in] client The client.
+ */
+TDJSON_EXPORT void td_json_client_destroy(void *client);
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif
diff --git a/libs/tdlib/td/td/telegram/td_log.cpp b/libs/tdlib/td/td/telegram/td_log.cpp
new file mode 100644
index 0000000000..2eb3605787
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/td_log.cpp
@@ -0,0 +1,27 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/td_log.h"
+
+#include "td/telegram/Log.h"
+
+#include <cstdint>
+
+int td_set_log_file_path(const char *file_path) {
+  return static_cast<int>(td::Log::set_file_path(file_path == nullptr ? "" : file_path));
+}
+
+void td_set_log_max_file_size(long long max_file_size) {
+  td::Log::set_max_file_size(static_cast<std::int64_t>(max_file_size));
+}
+
+void td_set_log_verbosity_level(int new_verbosity_level) {
+  td::Log::set_verbosity_level(new_verbosity_level);
+}
+
+void td_set_log_fatal_error_callback(td_log_fatal_error_callback_ptr callback) {
+  td::Log::set_fatal_error_callback(callback);
+}
diff --git a/libs/tdlib/td/td/telegram/td_log.h b/libs/tdlib/td/td/telegram/td_log.h
new file mode 100644
index 0000000000..51ab6393a2
--- /dev/null
+++ b/libs/tdlib/td/td/telegram/td_log.h
@@ -0,0 +1,76 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+/**
+ * \file
+ * C interface for managing the internal logging of TDLib.
+ * By default TDLib writes logs to stderr or an OS specific log and uses a verbosity level of 5.
+ */
+
+#include "td/telegram/tdjson_export.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Sets the path to the file where the internal TDLib log will be written.
+ * By default TDLib writes logs to stderr or an OS specific log.
+ * Use this method to write the log to a file instead.
+ *
+ * \param[in]  file_path Null-terminated path to a file where the internal TDLib log will be written.
+ *                       Use an empty path to switch back to the default logging behaviour.
+ * \return True 1 on success, or 0 otherwise, i.e. if the file can't be opened for writing.
+ */
+TDJSON_EXPORT int td_set_log_file_path(const char *file_path);
+
+/**
+ * Sets maximum size of the file to where the internal TDLib log is written before the file will be auto-rotated.
+ * Unused if log is not written to a file. Defaults to 10 MB.
+ *
+ * \param[in]  max_file_size Maximum size of the file to where the internal TDLib log is written before the file
+ *                           will be auto-rotated. Should be positive.
+ */
+TDJSON_EXPORT void td_set_log_max_file_size(long long max_file_size);
+
+/**
+ * Sets the verbosity level of the internal logging of TDLib.
+ * By default the TDLib uses a log verbosity level of 5.
+ *
+ * \param[in]  new_verbosity_level New value of logging verbosity level.
+ *                                 Value 0 corresponds to fatal errors,
+ *                                 value 1 corresponds to errors,
+ *                                 value 2 corresponds to warnings and debug warnings,
+ *                                 value 3 corresponds to informational,
+ *                                 value 4 corresponds to debug,
+ *                                 value 5 corresponds to verbose debug,
+ *                                 value greater than 5 and up to 1024 can be used to enable even more logging.
+ */
+TDJSON_EXPORT void td_set_log_verbosity_level(int new_verbosity_level);
+
+/**
+ * A type of callback function that will be called when a fatal error happens.
+ *
+ * \param error_message Null-terminated string with a description of a happened fatal error.
+ */
+typedef void (*td_log_fatal_error_callback_ptr)(const char *error_message);
+
+/**
+ * Sets the callback that will be called when a fatal error happens.
+ * None of the TDLib methods can be called from the callback.
+ * The TDLib will crash as soon as callback returns.
+ * By default the callback is not set.
+ *
+ * \param[in]  callback Callback that will be called when a fatal error happens.
+ *                      Pass NULL to remove the callback.
+ */
+TDJSON_EXPORT void td_set_log_fatal_error_callback(td_log_fatal_error_callback_ptr callback);
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif
diff --git a/libs/tdlib/td/td/tl/TlObject.h b/libs/tdlib/td/td/tl/TlObject.h
new file mode 100644
index 0000000000..4fcbf6bc46
--- /dev/null
+++ b/libs/tdlib/td/td/tl/TlObject.h
@@ -0,0 +1,172 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+/**
+ * \file
+ * Contains the declarations of a base class for all TL-objects and some helper methods
+ */
+
+#include <cstdint>
+#include <memory>
+#include <string>
+#include <utility>
+
+namespace td {
+
+class TlStorerCalcLength;
+
+class TlStorerUnsafe;
+
+class TlStorerToString;
+
+/**
+ * This class is a base class for all TDLib TL-objects.
+ */
+class TlObject {
+ public:
+  /**
+   * Returns an identifier, uniquely determining the TL-type of the object.
+   */
+  virtual std::int32_t get_id() const = 0;
+
+  /**
+   * Appends the object to the storer serializing object, a buffer of fixed length.
+   * \param[in] s Storer to which the object will be appended.
+   */
+  virtual void store(TlStorerUnsafe &s) const {
+  }
+
+  /**
+   * Appends the object to the storer, calculating the TL-length of the serialized object.
+   * \param[in] s Storer to which the object will be appended.
+   */
+  virtual void store(TlStorerCalcLength &s) const {
+  }
+
+  /**
+   * Helper function for the to_string method. Appends a string representation of the object to the storer.
+   * \param[in] s Storer to which the object string representation will be appended.
+   * \param[in] field_name Object field_name if applicable.
+   */
+  virtual void store(TlStorerToString &s, const char *field_name) const = 0;
+
+  /**
+   * Default constructor.
+   */
+  TlObject() = default;
+
+  /**
+   * Deleted copy constructor.
+   */
+  TlObject(const TlObject &) = delete;
+
+  /**
+   * Deleted copy assignment operator.
+   */
+  TlObject &operator=(const TlObject &) = delete;
+
+  /**
+   * Default move constructor.
+   */
+  TlObject(TlObject &&) = default;
+
+  /**
+   * Default move assignment operator.
+   */
+  TlObject &operator=(TlObject &&) = default;
+
+  /**
+   * Virtual destructor.
+   */
+  virtual ~TlObject() = default;
+};
+
+/**
+ * A smart wrapper to store a pointer to a TL-object.
+ */
+template <class Type>
+using tl_object_ptr = std::unique_ptr<Type>;
+
+/**
+ * A function to create a dynamically allocated TL-object. Can be treated as an analogue of std::make_unique.
+ * Usage example:
+ * \code
+ * auto get_authorization_state_request = td::make_tl_object<td::td_api::getAuthorizationState>();
+ * auto message_text = td::make_tl_object<td::td_api::formattedText>("Hello, world!!!",
+ *                     std::vector<td::tl_object_ptr<td::td_api::textEntities>>());
+ * auto send_message_request = td::make_tl_object<td::td_api::sendMessage>(chat_id, 0, false, false, nullptr,
+ *      td::make_tl_object<td::td_api::inputMessageText>(std::move(message_text), false, true));
+ * \endcode
+ *
+ * \tparam Type Type of the TL-object to construct.
+ * \param[in] args Arguments to pass to the object constructor.
+ * \return Wrapped pointer to the created TL-object.
+ */
+template <class Type, class... Args>
+tl_object_ptr<Type> make_tl_object(Args &&... args) {
+  return tl_object_ptr<Type>(new Type(std::forward<Args>(args)...));
+}
+
+/**
+ * A function to downcast a wrapped pointer to a TL-object to a pointer to its subclass.
+ * Casting an object to an incorrect type will lead to undefined behaviour.
+ * Examples of usage:
+ * \code
+ * td::tl_object_ptr<td::td_api::callState> call_state = ...;
+ * switch (call_state->get_id()) {
+ *   case td::td_api::callStatePending::ID: {
+ *     auto state = td::move_tl_object_as<td::td_api::callStatePending>(call_state);
+ *     // use state
+ *     break;
+ *   }
+ *   case td::td_api::callStateExchangingKeys::ID: {
+ *     // no additional fields, so cast isn't needed
+ *     break;
+ *   }
+ *   case td::td_api::callStateReady::ID: {
+ *     auto state = td::move_tl_object_as<td::td_api::callStateReady>(call_state);
+ *     // use state
+ *     break;
+ *   }
+ *   case td::td_api::callStateHangingUp::ID: {
+ *     // no additional fields, so cast isn't needed
+ *     break;
+ *   }
+ *   case td::td_api::callStateDiscarded::ID: {
+ *     auto state = td::move_tl_object_as<td::td_api::callStateDiscarded>(call_state);
+ *     // use state
+ *     break;
+ *   }
+ *   case td::td_api::callStateError::ID: {
+ *     auto state = td::move_tl_object_as<td::td_api::callStateError>(call_state);
+ *     // use state
+ *     break;
+ *   }
+ *   default:
+ *     assert(false);
+ * }
+ * \endcode
+ *
+ * \tparam ToT Type of a TL-object to move to.
+ * \tparam FromT Type of a TL-object to move from, this is auto-deduced.
+ * \param[in] from Wrapped pointer to a TL-object.
+ */
+template <class ToT, class FromT>
+tl_object_ptr<ToT> move_tl_object_as(tl_object_ptr<FromT> &from) {
+  return tl_object_ptr<ToT>(static_cast<ToT *>(from.release()));
+}
+
+/**
+ * \overload
+ */
+template <class ToT, class FromT>
+tl_object_ptr<ToT> move_tl_object_as(tl_object_ptr<FromT> &&from) {
+  return tl_object_ptr<ToT>(static_cast<ToT *>(from.release()));
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/tl/tl_dotnet_object.h b/libs/tdlib/td/td/tl/tl_dotnet_object.h
new file mode 100644
index 0000000000..57b18b22c1
--- /dev/null
+++ b/libs/tdlib/td/td/tl/tl_dotnet_object.h
@@ -0,0 +1,179 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/CxCli.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/td_api.hpp"
+
+namespace Telegram {
+namespace Td {
+namespace Api {
+
+using namespace CxCli;
+
+public ref class NativeObject sealed {
+public:
+  virtual ~NativeObject() {
+    if (data != nullptr) {
+      get_object_ptr();
+    }
+  }
+internal:
+  explicit NativeObject(td::td_api::BaseObject *fromData) {
+    data = static_cast<void *>(fromData);
+  }
+  td::td_api::object_ptr<td::td_api::BaseObject> get_object_ptr() {
+    auto res = static_cast<td::td_api::BaseObject *>(data);
+    data = nullptr;
+    return td::td_api::object_ptr<td::td_api::BaseObject>(res);
+  }
+  void *data;
+};
+
+public interface class BaseObject {
+public:
+  virtual NativeObject^ ToUnmanaged();
+};
+
+// from unmanaged
+inline bool FromUnmanaged(bool val) {
+  return val;
+}
+
+inline int32 FromUnmanaged(int32 val) {
+  return val;
+}
+
+inline int64 FromUnmanaged(int64 val) {
+  return val;
+}
+
+inline float64 FromUnmanaged(float64 val) {
+  return val;
+}
+
+inline String^ FromUnmanaged(const std::string &from) {
+  return string_from_unmanaged(from);
+}
+
+inline auto CLRCALL BytesFromUnmanaged(const std::string &from) {
+  Array<byte>^ res = REF_NEW Vector<byte>(static_cast<ArrayIndexType>(from.size()));
+  ArrayIndexType i = 0;
+  for (auto b : from) {
+    ArraySet(res, i++, b);
+  }
+  return res;
+}
+
+template <class FromT>
+auto CLRCALL FromUnmanaged(std::vector<FromT> &vec) {
+  using ToT = decltype(FromUnmanaged(vec[0]));
+  Array<ToT>^ res = REF_NEW Vector<ToT>(static_cast<ArrayIndexType>(vec.size()));
+  ArrayIndexType i = 0;
+  for (auto &from : vec) {
+    ArraySet(res, i++, FromUnmanaged(from));
+  }
+  return res;
+}
+
+template <class T>
+auto CLRCALL FromUnmanaged(td::td_api::object_ptr<T> &from) -> decltype(FromUnmanaged(*from.get())) {
+  if (!from) {
+    return nullptr;
+  }
+  return FromUnmanaged(*from.get());
+}
+
+template <class ResT>
+ref class CallFromUnmanagedRes {
+public:
+  static property ResT res;
+};
+
+template <class ResT>
+struct CallFromUnmanaged {
+  template <class T>
+  void operator()(T &val) const {
+    CallFromUnmanagedRes<ResT>::res = FromUnmanaged(val);
+  }
+};
+
+inline BaseObject^ FromUnmanaged(td::td_api::Function &from) {
+  CallFromUnmanaged<BaseObject^> res;
+  downcast_call(from, res);
+  return CallFromUnmanagedRes<BaseObject^>::res;
+}
+
+inline BaseObject^ FromUnmanaged(td::td_api::Object &from) {
+  CallFromUnmanaged<BaseObject^> res;
+  downcast_call(from, res);
+  return CallFromUnmanagedRes<BaseObject^>::res;
+}
+
+// to unmanaged
+inline bool ToUnmanaged(bool val) {
+  return val;
+}
+inline int32 ToUnmanaged(int32 val) {
+  return val;
+}
+
+inline int64 ToUnmanaged(int64 val) {
+  return val;
+}
+
+inline float64 ToUnmanaged(float64 val) {
+  return val;
+}
+
+inline std::string ToUnmanaged(String ^from) {
+  return string_to_unmanaged(from);
+}
+
+inline std::string ToUnmanaged(Array<byte>^ from) {
+  if (!from) {
+    return std::string();
+  }
+
+  ArrayIndexType size = ArraySize(from);
+  std::string res(size, '\0');
+  for (ArrayIndexType i = 0; i < size; i++) {
+    res[i] = static_cast<char>(ArrayGet(from, i));
+  }
+  return res;
+}
+
+template <class FromT>
+auto ToUnmanaged(Array<FromT>^ from) {
+  std::vector<decltype(ToUnmanaged(ArrayGet(from, 0)))> res;
+  if (from && ArraySize(from)) {
+    ArrayIndexType size = ArraySize(from);
+    res.reserve(size);
+    for (ArrayIndexType i = 0; i < size; i++) {
+      res.push_back(ToUnmanaged(ArrayGet(from, i)));
+    }
+  }
+  return res;
+}
+
+inline NativeObject^ ToUnmanaged(BaseObject^ from) {
+  if (!from) {
+    return REF_NEW NativeObject(nullptr);
+  }
+
+  return from->ToUnmanaged();
+}
+
+inline String^ ToString(BaseObject^ from) {
+  return string_from_unmanaged(td::td_api::to_string(ToUnmanaged(from)->get_object_ptr()));
+}
+
+}  // namespace Api
+}  // namespace Td
+}  // namespace Telegram
diff --git a/libs/tdlib/td/td/tl/tl_jni_object.cpp b/libs/tdlib/td/td/tl/tl_jni_object.cpp
new file mode 100644
index 0000000000..5074017b90
--- /dev/null
+++ b/libs/tdlib/td/td/tl/tl_jni_object.cpp
@@ -0,0 +1,352 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/tl/tl_jni_object.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Slice.h"
+
+#include <memory>
+
+namespace td {
+namespace jni {
+
+thread_local bool parse_error;
+
+static jclass BooleanClass;
+static jclass IntegerClass;
+static jclass LongClass;
+static jclass DoubleClass;
+static jclass StringClass;
+static jclass ObjectClass;
+jclass ArrayKeyboardButtonClass;
+jclass ArrayInlineKeyboardButtonClass;
+jmethodID GetConstructorID;
+jmethodID BooleanGetValueMethodID;
+jmethodID IntegerGetValueMethodID;
+jmethodID LongGetValueMethodID;
+jmethodID DoubleGetValueMethodID;
+
+static void fatal_error(JNIEnv *env, CSlice error) {
+  LOG(ERROR) << error;
+  env->FatalError(error.c_str());
+}
+
+jclass get_jclass(JNIEnv *env, const char *class_name) {
+  jclass clazz = env->FindClass(class_name);
+  if (!clazz) {
+    fatal_error(env, PSLICE() << "Can't find class [" << class_name << "]");
+  }
+  jclass clazz_global = (jclass)env->NewGlobalRef(clazz);
+
+  env->DeleteLocalRef(clazz);
+
+  if (!clazz_global) {
+    fatal_error(env, PSLICE() << "Can't create global reference to [" << class_name << "]");
+  }
+
+  return clazz_global;
+}
+
+jmethodID get_method_id(JNIEnv *env, jclass clazz, const char *name, const char *signature) {
+  jmethodID res = env->GetMethodID(clazz, name, signature);
+  if (!res) {
+    fatal_error(env, PSLICE() << "Can't find method [" << name << "] with signature [" << signature << "]");
+  }
+  return res;
+}
+
+jfieldID get_field_id(JNIEnv *env, jclass clazz, const char *name, const char *signature) {
+  jfieldID res = env->GetFieldID(clazz, name, signature);
+  if (!res) {
+    fatal_error(env, PSLICE() << "Can't find field [" << name << "] with signature [" << signature << "]");
+  }
+  return res;
+}
+
+void register_native_method(JNIEnv *env, jclass clazz, std::string name, std::string signature, void *function_ptr) {
+  JNINativeMethod native_method{&name[0], &signature[0], function_ptr};
+  if (env->RegisterNatives(clazz, &native_method, 1) != 0) {
+    fatal_error(env, PSLICE() << "RegisterNatives failed for " << name << " with signature " << signature);
+  }
+}
+
+std::unique_ptr<JNIEnv, JvmThreadDetacher> get_jni_env(JavaVM *java_vm, jint jni_version) {
+  JNIEnv *env = nullptr;
+  if (java_vm->GetEnv(reinterpret_cast<void **>(&env), jni_version) == JNI_EDETACHED) {
+#ifdef JDK1_2  // if not Android JNI
+    auto p_env = reinterpret_cast<void **>(&env);
+#else
+    auto p_env = &env;
+#endif
+    java_vm->AttachCurrentThread(p_env, nullptr);
+  } else {
+    java_vm = nullptr;
+  }
+
+  return std::unique_ptr<JNIEnv, JvmThreadDetacher>(env, JvmThreadDetacher(java_vm));
+}
+
+void init_vars(JNIEnv *env, const char *td_api_java_package) {
+  BooleanClass = get_jclass(env, "java/lang/Boolean");
+  IntegerClass = get_jclass(env, "java/lang/Integer");
+  LongClass = get_jclass(env, "java/lang/Long");
+  DoubleClass = get_jclass(env, "java/lang/Double");
+  StringClass = get_jclass(env, "java/lang/String");
+  ObjectClass = get_jclass(env, (PSLICE() << td_api_java_package << "/TdApi$Object").c_str());
+  ArrayKeyboardButtonClass =
+      get_jclass(env, (PSLICE() << "[L" << td_api_java_package << "/TdApi$KeyboardButton;").c_str());
+  ArrayInlineKeyboardButtonClass =
+      get_jclass(env, (PSLICE() << "[L" << td_api_java_package << "/TdApi$InlineKeyboardButton;").c_str());
+  GetConstructorID = get_method_id(env, ObjectClass, "getConstructor", "()I");
+  BooleanGetValueMethodID = get_method_id(env, BooleanClass, "booleanValue", "()Z");
+  IntegerGetValueMethodID = get_method_id(env, IntegerClass, "intValue", "()I");
+  LongGetValueMethodID = get_method_id(env, LongClass, "longValue", "()J");
+  DoubleGetValueMethodID = get_method_id(env, DoubleClass, "doubleValue", "()D");
+}
+
+static size_t get_utf8_from_utf16_length(const jchar *p, jsize len) {
+  size_t result = 0;
+  for (jsize i = 0; i < len; i++) {
+    unsigned int cur = p[i];
+    if ((cur & 0xF800) == 0xD800) {
+      if (i < len) {
+        unsigned int next = p[++i];
+        if ((next & 0xFC00) == 0xDC00 && (cur & 0x400) == 0) {
+          result += 4;
+          continue;
+        }
+      }
+
+      // TODO wrong UTF-16, it is possible
+      return 0;
+    }
+    result += 1 + (cur >= 0x80) + (cur >= 0x800);
+  }
+  return result;
+}
+
+static void utf16_to_utf8(const jchar *p, jsize len, char *res) {
+  for (jsize i = 0; i < len; i++) {
+    unsigned int cur = p[i];
+    // TODO conversion unsigned int -> signed char is implementation defined
+    if (cur <= 0x7f) {
+      *res++ = static_cast<char>(cur);
+    } else if (cur <= 0x7ff) {
+      *res++ = static_cast<char>(0xc0 | (cur >> 6));
+      *res++ = static_cast<char>(0x80 | (cur & 0x3f));
+    } else if ((cur & 0xF800) != 0xD800) {
+      *res++ = static_cast<char>(0xe0 | (cur >> 12));
+      *res++ = static_cast<char>(0x80 | ((cur >> 6) & 0x3f));
+      *res++ = static_cast<char>(0x80 | (cur & 0x3f));
+    } else {
+      // correctness is already checked
+      unsigned int next = p[++i];
+      unsigned int val = ((cur - 0xD800) << 10) + next - 0xDC00 + 0x10000;
+
+      *res++ = static_cast<char>(0xf0 | (val >> 18));
+      *res++ = static_cast<char>(0x80 | ((val >> 12) & 0x3f));
+      *res++ = static_cast<char>(0x80 | ((val >> 6) & 0x3f));
+      *res++ = static_cast<char>(0x80 | (val & 0x3f));
+    }
+  }
+}
+
+static jsize get_utf16_from_utf8_length(const char *p, size_t len, jsize *surrogates) {
+  // UTF-8 correctness is supposed
+  jsize result = 0;
+  for (size_t i = 0; i < len; i++) {
+    result += ((p[i] & 0xc0) != 0x80);
+    *surrogates += ((p[i] & 0xf8) == 0xf0);
+  }
+  return result;
+}
+
+static void utf8_to_utf16(const char *p, size_t len, jchar *res) {
+  // UTF-8 correctness is supposed
+  for (size_t i = 0; i < len;) {
+    unsigned int a = static_cast<unsigned char>(p[i++]);
+    if (a >= 0x80) {
+      unsigned int b = static_cast<unsigned char>(p[i++]);
+      if (a >= 0xe0) {
+        unsigned int c = static_cast<unsigned char>(p[i++]);
+        if (a >= 0xf0) {
+          unsigned int d = static_cast<unsigned char>(p[i++]);
+          unsigned int val = ((a & 0x07) << 18) + ((b & 0x3f) << 12) + ((c & 0x3f) << 6) + (d & 0x3f) - 0x10000;
+          *res++ = static_cast<jchar>(0xD800 + (val >> 10));
+          *res++ = static_cast<jchar>(0xDC00 + (val & 0x3ff));
+        } else {
+          *res++ = static_cast<jchar>(((a & 0x0f) << 12) + ((b & 0x3f) << 6) + (c & 0x3f));
+        }
+      } else {
+        *res++ = static_cast<jchar>(((a & 0x1f) << 6) + (b & 0x3f));
+      }
+    } else {
+      *res++ = static_cast<jchar>(a);
+    }
+  }
+}
+
+std::string fetch_string(JNIEnv *env, jobject o, jfieldID id) {
+  jstring s = (jstring)env->GetObjectField(o, id);
+  if (s == nullptr) {
+    // treat null as an empty string
+    return std::string();
+  }
+  std::string res = from_jstring(env, s);
+  env->DeleteLocalRef(s);
+  return res;
+}
+
+std::string from_jstring(JNIEnv *env, jstring s) {
+  if (!s) {
+    return "";
+  }
+  jsize s_len = env->GetStringLength(s);
+  const jchar *p = env->GetStringChars(s, nullptr);
+  if (p == nullptr) {
+    parse_error = true;
+    return std::string();
+  }
+  size_t len = get_utf8_from_utf16_length(p, s_len);
+  std::string res(len, '\0');
+  if (len) {
+    utf16_to_utf8(p, s_len, &res[0]);
+  }
+  env->ReleaseStringChars(s, p);
+  return res;
+}
+
+jstring to_jstring(JNIEnv *env, const std::string &s) {
+  jsize surrogates = 0;
+  jsize unicode_len = get_utf16_from_utf8_length(s.c_str(), s.size(), &surrogates);
+  if (surrogates == 0) {
+    // TODO '\0'
+    return env->NewStringUTF(s.c_str());
+  }
+  jsize result_len = surrogates + unicode_len;
+  if (result_len <= 256) {
+    jchar result[256];
+    utf8_to_utf16(s.c_str(), s.size(), result);
+    return env->NewString(result, result_len);
+  }
+
+  auto result = std::make_unique<jchar[]>(result_len);
+  utf8_to_utf16(s.c_str(), s.size(), result.get());
+  return env->NewString(result.get(), result_len);
+}
+
+std::string from_bytes(JNIEnv *env, jbyteArray arr) {
+  std::string b;
+  if (arr != nullptr) {
+    jsize length = env->GetArrayLength(arr);
+    if (length != 0) {
+      b.resize(narrow_cast<size_t>(length));
+      env->GetByteArrayRegion(arr, 0, length, reinterpret_cast<jbyte *>(&b[0]));
+    }
+    env->DeleteLocalRef(arr);
+  }
+  return b;
+}
+
+jbyteArray to_bytes(JNIEnv *env, const std::string &b) {
+  static_assert(sizeof(char) == sizeof(jbyte), "Mismatched jbyte size");
+  jsize length = narrow_cast<jsize>(b.size());
+  jbyteArray arr = env->NewByteArray(length);
+  if (arr != nullptr && length != 0) {
+    env->SetByteArrayRegion(arr, 0, length, reinterpret_cast<const jbyte *>(b.data()));
+  }
+  return arr;
+}
+
+jintArray store_vector(JNIEnv *env, const std::vector<std::int32_t> &v) {
+  static_assert(sizeof(std::int32_t) == sizeof(jint), "Mismatched jint size");
+  jsize length = narrow_cast<jsize>(v.size());
+  jintArray arr = env->NewIntArray(length);
+  if (arr != nullptr && length != 0) {
+    env->SetIntArrayRegion(arr, 0, length, reinterpret_cast<const jint *>(&v[0]));
+  }
+  return arr;
+}
+
+jlongArray store_vector(JNIEnv *env, const std::vector<std::int64_t> &v) {
+  static_assert(sizeof(std::int64_t) == sizeof(jlong), "Mismatched jlong size");
+  jsize length = narrow_cast<jsize>(v.size());
+  jlongArray arr = env->NewLongArray(length);
+  if (arr != nullptr && length != 0) {
+    env->SetLongArrayRegion(arr, 0, length, reinterpret_cast<const jlong *>(&v[0]));
+  }
+  return arr;
+}
+
+jdoubleArray store_vector(JNIEnv *env, const std::vector<double> &v) {
+  static_assert(sizeof(double) == sizeof(jdouble), "Mismatched jdouble size");
+  jsize length = narrow_cast<jsize>(v.size());
+  jdoubleArray arr = env->NewDoubleArray(length);
+  if (arr != nullptr && length != 0) {
+    env->SetDoubleArrayRegion(arr, 0, length, reinterpret_cast<const jdouble *>(&v[0]));
+  }
+  return arr;
+}
+
+jobjectArray store_vector(JNIEnv *env, const std::vector<std::string> &v) {
+  jsize length = narrow_cast<jsize>(v.size());
+  jobjectArray arr = env->NewObjectArray(length, StringClass, 0);
+  if (arr != nullptr) {
+    for (jsize i = 0; i < length; i++) {
+      jstring str = to_jstring(env, v[i]);
+      if (str) {
+        env->SetObjectArrayElement(arr, i, str);
+        env->DeleteLocalRef(str);
+      }
+    }
+  }
+  return arr;
+}
+
+std::vector<std::int32_t> fetch_vector(JNIEnv *env, jintArray arr) {
+  std::vector<std::int32_t> result;
+  if (arr != nullptr) {
+    jsize length = env->GetArrayLength(arr);
+    if (length != 0) {
+      result.resize(length);
+      env->GetIntArrayRegion(arr, 0, length, reinterpret_cast<jint *>(&result[0]));
+    }
+    env->DeleteLocalRef(arr);
+  }
+  return result;
+}
+
+std::vector<std::int64_t> fetch_vector(JNIEnv *env, jlongArray arr) {
+  std::vector<std::int64_t> result;
+  if (arr != nullptr) {
+    jsize length = env->GetArrayLength(arr);
+    if (length != 0) {
+      result.resize(length);
+      env->GetLongArrayRegion(arr, 0, length, reinterpret_cast<jlong *>(&result[0]));
+    }
+    env->DeleteLocalRef(arr);
+  }
+  return result;
+}
+
+std::vector<double> fetch_vector(JNIEnv *env, jdoubleArray arr) {
+  std::vector<double> result;
+  if (arr != nullptr) {
+    jsize length = env->GetArrayLength(arr);
+    if (length != 0) {
+      result.resize(length);
+      env->GetDoubleArrayRegion(arr, 0, length, reinterpret_cast<jdouble *>(&result[0]));
+    }
+    env->DeleteLocalRef(arr);
+  }
+  return result;
+}
+
+}  // namespace jni
+}  // namespace td
diff --git a/libs/tdlib/td/td/tl/tl_jni_object.h b/libs/tdlib/td/td/tl/tl_jni_object.h
new file mode 100644
index 0000000000..418d47df9e
--- /dev/null
+++ b/libs/tdlib/td/td/tl/tl_jni_object.h
@@ -0,0 +1,231 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include <jni.h>
+
+#include <cstdint>
+#include <memory>
+#include <string>
+#include <vector>
+
+namespace td {
+namespace td_api {
+class keyboardButton;
+class inlineKeyboardButton;
+}  // namespace td_api
+
+namespace jni {
+
+extern thread_local bool parse_error;
+
+extern jclass ArrayKeyboardButtonClass;
+extern jclass ArrayInlineKeyboardButtonClass;
+extern jmethodID GetConstructorID;
+extern jmethodID BooleanGetValueMethodID;
+extern jmethodID IntegerGetValueMethodID;
+extern jmethodID LongGetValueMethodID;
+extern jmethodID DoubleGetValueMethodID;
+
+jclass get_jclass(JNIEnv *env, const char *class_name);
+
+jmethodID get_method_id(JNIEnv *env, jclass clazz, const char *name, const char *signature);
+
+jfieldID get_field_id(JNIEnv *env, jclass clazz, const char *name, const char *signature);
+
+void register_native_method(JNIEnv *env, jclass clazz, std::string name, std::string signature, void *function_ptr);
+
+class JvmThreadDetacher {
+  JavaVM *java_vm_;
+
+  void detach() {
+    if (java_vm_ != nullptr) {
+      java_vm_->DetachCurrentThread();
+      java_vm_ = nullptr;
+    }
+  }
+
+ public:
+  explicit JvmThreadDetacher(JavaVM *java_vm) : java_vm_(java_vm) {
+  }
+
+  JvmThreadDetacher(const JvmThreadDetacher &other) = delete;
+  JvmThreadDetacher &operator=(const JvmThreadDetacher &other) = delete;
+  JvmThreadDetacher(JvmThreadDetacher &&other) : java_vm_(other.java_vm_) {
+    other.java_vm_ = nullptr;
+  }
+  JvmThreadDetacher &operator=(JvmThreadDetacher &&other) = delete;
+  ~JvmThreadDetacher() {
+    detach();
+  }
+
+  void operator()(JNIEnv *env) {
+    detach();
+  }
+};
+
+std::unique_ptr<JNIEnv, JvmThreadDetacher> get_jni_env(JavaVM *java_vm, jint jni_version);
+
+std::string fetch_string(JNIEnv *env, jobject o, jfieldID id);
+
+inline jobject fetch_object(JNIEnv *env, const jobject &o, const jfieldID &id) {
+  // null return object is implicitly allowed
+  return env->GetObjectField(o, id);
+}
+
+inline bool have_parse_error() {
+  return parse_error;
+}
+
+inline void reset_parse_error() {
+  parse_error = false;
+}
+
+std::string from_jstring(JNIEnv *env, jstring s);
+
+jstring to_jstring(JNIEnv *env, const std::string &s);
+
+std::string from_bytes(JNIEnv *env, jbyteArray arr);
+
+jbyteArray to_bytes(JNIEnv *env, const std::string &b);
+
+void init_vars(JNIEnv *env, const char *td_api_java_package);
+
+jintArray store_vector(JNIEnv *env, const std::vector<std::int32_t> &v);
+
+jlongArray store_vector(JNIEnv *env, const std::vector<std::int64_t> &v);
+
+jdoubleArray store_vector(JNIEnv *env, const std::vector<double> &v);
+
+jobjectArray store_vector(JNIEnv *env, const std::vector<std::string> &v);
+
+template <class T>
+jobjectArray store_vector(JNIEnv *env, const std::vector<T> &v) {
+  jint length = static_cast<jint>(v.size());
+  jobjectArray arr = env->NewObjectArray(length, T::element_type::Class, jobject());
+  if (arr != nullptr) {
+    for (jint i = 0; i < length; i++) {
+      if (v[i] != nullptr) {
+        jobject stored_object;
+        v[i]->store(env, stored_object);
+        if (stored_object) {
+          env->SetObjectArrayElement(arr, i, stored_object);
+          env->DeleteLocalRef(stored_object);
+        }
+      }
+    }
+  }
+  return arr;
+}
+
+template <class T>
+class get_array_class {
+  static jclass get();
+};
+
+template <>
+class get_array_class<td_api::keyboardButton> {
+ public:
+  static jclass get() {
+    return ArrayKeyboardButtonClass;
+  }
+};
+
+template <>
+class get_array_class<td_api::inlineKeyboardButton> {
+ public:
+  static jclass get() {
+    return ArrayInlineKeyboardButtonClass;
+  }
+};
+
+template <class T>
+jobjectArray store_vector(JNIEnv *env, const std::vector<std::vector<T>> &v) {
+  jint length = static_cast<jint>(v.size());
+  jobjectArray arr = env->NewObjectArray(length, get_array_class<typename T::element_type>::get(), 0);
+  if (arr != nullptr) {
+    for (jint i = 0; i < length; i++) {
+      auto stored_array = store_vector(env, v[i]);
+      if (stored_array) {
+        env->SetObjectArrayElement(arr, i, stored_array);
+        env->DeleteLocalRef(stored_array);
+      }
+    }
+  }
+  return arr;
+}
+
+template <class T>
+auto fetch_tl_object(JNIEnv *env, jobject obj) {
+  decltype(T::fetch(env, obj)) result;
+  if (obj != nullptr) {
+    result = T::fetch(env, obj);
+    env->DeleteLocalRef(obj);
+  }
+  return result;
+}
+
+std::vector<std::int32_t> fetch_vector(JNIEnv *env, jintArray arr);
+
+std::vector<std::int64_t> fetch_vector(JNIEnv *env, jlongArray arr);
+
+std::vector<double> fetch_vector(JNIEnv *env, jdoubleArray arr);
+
+template <class T>
+struct FetchVector {
+  static auto fetch(JNIEnv *env, jobjectArray arr) {
+    std::vector<decltype(fetch_tl_object<T>(env, jobject()))> result;
+    if (arr != nullptr) {
+      jsize length = env->GetArrayLength(arr);
+      result.reserve(length);
+      for (jsize i = 0; i < length; i++) {
+        result.push_back(fetch_tl_object<T>(env, env->GetObjectArrayElement(arr, i)));
+      }
+      env->DeleteLocalRef(arr);
+    }
+    return result;
+  }
+};
+
+template <>
+struct FetchVector<std::string> {
+  static std::vector<std::string> fetch(JNIEnv *env, jobjectArray arr) {
+    std::vector<std::string> result;
+    if (arr != nullptr) {
+      jsize length = env->GetArrayLength(arr);
+      result.reserve(length);
+      for (jsize i = 0; i < length; i++) {
+        jstring str = (jstring)env->GetObjectArrayElement(arr, i);
+        result.push_back(jni::from_jstring(env, str));
+        if (str) {
+          env->DeleteLocalRef(str);
+        }
+      }
+      env->DeleteLocalRef(arr);
+    }
+    return result;
+  }
+};
+
+template <class T>
+struct FetchVector<std::vector<T>> {
+  static auto fetch(JNIEnv *env, jobjectArray arr) {
+    std::vector<decltype(FetchVector<T>::fetch(env, jobjectArray()))> result;
+    if (arr != nullptr) {
+      jsize length = env->GetArrayLength(arr);
+      result.reserve(length);
+      for (jsize i = 0; i < length; i++) {
+        result.push_back(FetchVector<T>::fetch(env, (jobjectArray)env->GetObjectArrayElement(arr, i)));
+      }
+      env->DeleteLocalRef(arr);
+    }
+    return result;
+  }
+};
+
+}  // namespace jni
+}  // namespace td
diff --git a/libs/tdlib/td/td/tl/tl_json.h b/libs/tdlib/td/td/tl/tl_json.h
new file mode 100644
index 0000000000..f8f21203da
--- /dev/null
+++ b/libs/tdlib/td/td/tl/tl_json.h
@@ -0,0 +1,225 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/base64.h"
+#include "td/utils/format.h"
+#include "td/utils/JsonBuilder.h"
+#include "td/utils/misc.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/tl_storers.h"
+
+#include "td/telegram/td_api.h"
+#include "td/telegram/td_api.hpp"
+
+#include <type_traits>
+
+namespace td {
+template <class T>
+class ToJsonImpl : public Jsonable {
+ public:
+  explicit ToJsonImpl(const T &value) : value_(value) {
+  }
+  void store(JsonValueScope *scope) const {
+    to_json(*scope, value_);
+  }
+
+ private:
+  const T &value_;
+};
+
+template <class T>
+auto ToJson(const T &value) {
+  return ToJsonImpl<T>(value);
+}
+
+template <class T>
+void to_json(JsonValueScope &jv, const T &value) {
+  jv << value;
+}
+
+struct JsonInt64 {
+  int64 value;
+};
+
+inline void to_json(JsonValueScope &jv, const JsonInt64 json_int64) {
+  jv << JsonString(PSLICE() << json_int64.value);
+}
+struct JsonVectorInt64 {
+  const std::vector<int64> &value;
+};
+
+inline void to_json(JsonValueScope &jv, const JsonVectorInt64 &vec) {
+  auto ja = jv.enter_array();
+  for (auto &value : vec.value) {
+    ja.enter_value() << ToJson(JsonInt64{value});
+  }
+}
+
+inline void to_json(JsonValueScope &jv, const td_api::Object &object) {
+  td_api::downcast_call(const_cast<td_api::Object &>(object), [&jv](const auto &object) { to_json(jv, object); });
+}
+inline void to_json(JsonValueScope &jv, const td_api::Function &object) {
+  td_api::downcast_call(const_cast<td_api::Function &>(object), [&jv](const auto &object) { to_json(jv, object); });
+}
+
+template <class T>
+void to_json(JsonValueScope &jv, const tl_object_ptr<T> &value) {
+  if (value) {
+    to_json(jv, *value);
+  } else {
+    jv << JsonNull();
+  }
+}
+
+template <class T>
+void to_json(JsonValueScope &jv, const std::vector<T> &v) {
+  auto ja = jv.enter_array();
+  for (auto &value : v) {
+    ja.enter_value() << ToJson(value);
+  }
+}
+
+inline Status from_json(int32 &to, JsonValue &from) {
+  if (from.type() != JsonValue::Type::Number && from.type() != JsonValue::Type::String) {
+    return Status::Error(PSLICE() << "Expected number, got " << from.type());
+  }
+  Slice number = from.type() == JsonValue::Type::String ? from.get_string() : from.get_number();
+  TRY_RESULT(res, to_integer_safe<int32>(number));
+  to = res;
+  return Status::OK();
+}
+
+inline Status from_json(bool &to, JsonValue &from) {
+  if (from.type() != JsonValue::Type::Boolean) {
+    int32 x;
+    auto status = from_json(x, from);
+    if (status.is_ok()) {
+      to = x != 0;
+      return Status::OK();
+    }
+    return Status::Error(PSLICE() << "Expected bool, got " << from.type());
+  }
+  to = from.get_boolean();
+  return Status::OK();
+}
+
+inline Status from_json(int64 &to, JsonValue &from) {
+  if (from.type() != JsonValue::Type::Number && from.type() != JsonValue::Type::String) {
+    return Status::Error(PSLICE() << "Expected number, got " << from.type());
+  }
+  Slice number = from.type() == JsonValue::Type::String ? from.get_string() : from.get_number();
+  TRY_RESULT(res, to_integer_safe<int64>(number));
+  to = res;
+  return Status::OK();
+}
+inline Status from_json(double &to, JsonValue &from) {
+  if (from.type() != JsonValue::Type::Number) {
+    return Status::Error(PSLICE() << "Expected number, got " << from.type());
+  }
+  to = to_double(from.get_number());
+  return Status::OK();
+}
+
+inline Status from_json(string &to, JsonValue &from) {
+  if (from.type() != JsonValue::Type::String) {
+    return Status::Error(PSLICE() << "Expected string, got " << from.type());
+  }
+  to = from.get_string().str();
+  return Status::OK();
+}
+
+inline Status from_json_bytes(string &to, JsonValue &from) {
+  if (from.type() != JsonValue::Type::String) {
+    return Status::Error(PSLICE() << "Expected string, got " << from.type());
+  }
+  TRY_RESULT(decoded, base64_decode(from.get_string()));
+  to = std::move(decoded);
+  return Status::OK();
+}
+
+template <class T>
+Status from_json(std::vector<T> &to, JsonValue &from) {
+  if (from.type() != JsonValue::Type::Array) {
+    return Status::Error(PSLICE() << "Expected array, got " << from.type());
+  }
+  to = std::vector<T>(from.get_array().size());
+  size_t i = 0;
+  for (auto &value : from.get_array()) {
+    TRY_STATUS(from_json(to[i], value));
+    i++;
+  }
+  return Status::OK();
+}
+
+template <class T>
+class DowncastHelper : public T {
+ public:
+  explicit DowncastHelper(int32 constructor) : constructor_(constructor) {
+  }
+  int32 get_id() const override {
+    return constructor_;
+  }
+  void store(TlStorerToString &s, const char *field_name) const override {
+  }
+
+ private:
+  int32 constructor_{0};
+};
+
+template <class T>
+std::enable_if_t<!std::is_constructible<T>::value, Status> from_json(tl_object_ptr<T> &to, JsonValue &from) {
+  if (from.type() != JsonValue::Type::Object) {
+    if (from.type() == JsonValue::Type::Null) {
+      to = nullptr;
+      return Status::OK();
+    }
+    return Status::Error(PSLICE() << "Expected object, got " << from.type());
+  }
+
+  auto &object = from.get_object();
+  TRY_RESULT(constructor_value, get_json_object_field(object, "@type", JsonValue::Type::Null, false));
+  int32 constructor = 0;
+  if (constructor_value.type() == JsonValue::Type::Number) {
+    constructor = to_integer<int32>(constructor_value.get_number());
+  } else if (constructor_value.type() == JsonValue::Type::String) {
+    TRY_RESULT(t_constructor, tl_constructor_from_string(to.get(), constructor_value.get_string().str()));
+    constructor = t_constructor;
+  } else {
+    return Status::Error(PSLICE() << "Expected string or int, got " << constructor_value.type());
+  }
+
+  DowncastHelper<T> helper(constructor);
+  Status status;
+  bool ok = downcast_call(static_cast<T &>(helper), [&](auto &dummy) {
+    auto result = make_tl_object<std::decay_t<decltype(dummy)>>();
+    status = from_json(*result, object);
+    to = std::move(result);
+  });
+  TRY_STATUS(std::move(status));
+  if (!ok) {
+    return Status::Error(PSLICE() << "Unknown constructor " << format::as_hex(constructor));
+  }
+
+  return Status::OK();
+}
+
+template <class T>
+std::enable_if_t<std::is_constructible<T>::value, Status> from_json(tl_object_ptr<T> &to, JsonValue &from) {
+  if (from.type() != JsonValue::Type::Object) {
+    if (from.type() == JsonValue::Type::Null) {
+      to = nullptr;
+      return Status::OK();
+    }
+    return Status::Error(PSLICE() << "Expected object, got " << from.type());
+  }
+  to = make_tl_object<T>();
+  return from_json(*to, from.get_object());
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/tl/tl_object_parse.h b/libs/tdlib/td/td/tl/tl_object_parse.h
new file mode 100644
index 0000000000..953e0940b3
--- /dev/null
+++ b/libs/tdlib/td/td/tl/tl_object_parse.h
@@ -0,0 +1,145 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/tl/TlObject.h"
+
+#include "td/utils/int_types.h"
+
+#include <cstdint>
+#include <memory>
+#include <string>
+#include <vector>
+
+namespace td {
+
+template <class Func, std::int32_t constructor_id>
+class TlFetchBoxed {
+ public:
+  template <class ParserT>
+  static auto parse(ParserT &p) -> decltype(Func::parse(p)) {
+    if (p.fetch_int() != constructor_id) {
+      p.set_error("Wrong constructor found");
+      return decltype(Func::parse(p))();
+    }
+    return Func::parse(p);
+  }
+};
+
+class TlFetchTrue {
+ public:
+  template <class ParserT>
+  static bool parse(ParserT &p) {
+    return true;
+  }
+};
+
+class TlFetchBool {
+ public:
+  template <class ParserT>
+  static bool parse(ParserT &p) {
+    constexpr std::int32_t ID_BOOL_FALSE = 0xbc799737;
+    constexpr std::int32_t ID_BOOL_TRUE = 0x997275b5;
+
+    std::int32_t c = p.fetch_int();
+    if (c == ID_BOOL_TRUE) {
+      return true;
+    }
+    if (c != ID_BOOL_FALSE) {
+      p.set_error("Bool expected");
+    }
+    return false;
+  }
+};
+
+class TlFetchInt {
+ public:
+  template <class ParserT>
+  static std::int32_t parse(ParserT &p) {
+    return p.fetch_int();
+  }
+};
+
+class TlFetchLong {
+ public:
+  template <class ParserT>
+  static std::int64_t parse(ParserT &p) {
+    return p.fetch_long();
+  }
+};
+
+class TlFetchDouble {
+ public:
+  template <class ParserT>
+  static double parse(ParserT &p) {
+    return p.fetch_double();
+  }
+};
+
+class TlFetchInt128 {
+ public:
+  template <class ParserT>
+  static UInt128 parse(ParserT &p) {
+    return p.template fetch_binary<UInt128>();
+  }
+};
+
+class TlFetchInt256 {
+ public:
+  template <class ParserT>
+  static UInt256 parse(ParserT &p) {
+    return p.template fetch_binary<UInt256>();
+  }
+};
+
+template <class T>
+class TlFetchString {
+ public:
+  template <class ParserT>
+  static T parse(ParserT &p) {
+    return p.template fetch_string<T>();
+  }
+};
+
+template <class T>
+class TlFetchBytes {
+ public:
+  template <class ParserT>
+  static T parse(ParserT &p) {
+    return p.template fetch_string<T>();
+  }
+};
+
+template <class Func>
+class TlFetchVector {
+ public:
+  template <class ParserT>
+  static auto parse(ParserT &p) -> std::vector<decltype(Func::parse(p))> {
+    const std::uint32_t multiplicity = p.fetch_int();
+    std::vector<decltype(Func::parse(p))> v;
+    if (p.get_left_len() < multiplicity) {
+      p.set_error("Wrong vector length");
+    } else {
+      v.reserve(multiplicity);
+      for (std::uint32_t i = 0; i < multiplicity; i++) {
+        v.push_back(Func::parse(p));
+      }
+    }
+    return v;
+  }
+};
+
+template <class T>
+class TlFetchObject {
+ public:
+  template <class ParserT>
+  static tl_object_ptr<T> parse(ParserT &p) {
+    return T::fetch(p);
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/td/tl/tl_object_store.h b/libs/tdlib/td/td/tl/tl_object_store.h
new file mode 100644
index 0000000000..f6cd376692
--- /dev/null
+++ b/libs/tdlib/td/td/tl/tl_object_store.h
@@ -0,0 +1,95 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/tl/TlObject.h"
+
+#include "td/utils/misc.h"
+
+#include <cstdint>
+#include <memory>
+#include <string>
+#include <vector>
+
+namespace td {
+
+template <class Func, std::int32_t constructor_id>
+class TlStoreBoxed {
+ public:
+  template <class T, class StorerT>
+  static void store(const T &x, StorerT &s) {
+    s.store_binary(constructor_id);
+    Func::store(x, s);
+  }
+};
+
+template <class Func>
+class TlStoreBoxedUnknown {
+ public:
+  template <class T, class StorerT>
+  static void store(const T &x, StorerT &s) {
+    s.store_binary(x->get_id());
+    Func::store(x, s);
+  }
+};
+
+class TlStoreBool {
+ public:
+  template <class StorerT>
+  static void store(const bool &x, StorerT &s) {
+    constexpr std::int32_t ID_BOOL_FALSE = 0xbc799737;
+    constexpr std::int32_t ID_BOOL_TRUE = 0x997275b5;
+
+    s.store_binary(x ? ID_BOOL_TRUE : ID_BOOL_FALSE);
+  }
+};
+
+class TlStoreTrue {
+ public:
+  template <class StorerT>
+  static void store(const bool &x, StorerT &s) {
+    // currently nothing to do
+  }
+};
+
+class TlStoreBinary {
+ public:
+  template <class T, class StorerT>
+  static void store(const T &x, StorerT &s) {
+    s.store_binary(x);
+  }
+};
+
+class TlStoreString {
+ public:
+  template <class T, class StorerT>
+  static void store(const T &x, StorerT &s) {
+    s.store_string(x);
+  }
+};
+
+template <class Func>
+class TlStoreVector {
+ public:
+  template <class T, class StorerT>
+  static void store(const T &vec, StorerT &s) {
+    s.store_binary(narrow_cast<int32>(vec.size()));
+    for (auto &val : vec) {
+      Func::store(val, s);
+    }
+  }
+};
+
+class TlStoreObject {
+ public:
+  template <class T, class StorerT>
+  static void store(const tl_object_ptr<T> &obj, StorerT &s) {
+    return obj->store(s);
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/CMakeLists.txt b/libs/tdlib/td/tdactor/CMakeLists.txt
new file mode 100644
index 0000000000..c0c83025e5
--- /dev/null
+++ b/libs/tdlib/td/tdactor/CMakeLists.txt
@@ -0,0 +1,65 @@
+cmake_minimum_required(VERSION 3.0.2 FATAL_ERROR)
+
+#SOURCE SETS
+set(TDACTOR_SOURCE
+  td/actor/impl/ConcurrentScheduler.cpp
+  td/actor/impl/Scheduler.cpp
+  td/actor/MultiPromise.cpp
+  td/actor/Timeout.cpp
+
+  td/actor/impl2/Scheduler.cpp
+
+  td/actor/impl/Actor-decl.h
+  td/actor/impl/Actor.h
+  td/actor/impl/ActorId-decl.h
+  td/actor/impl/ActorId.h
+  td/actor/impl/ActorInfo-decl.h
+  td/actor/impl/ActorInfo.h
+  td/actor/impl/EventFull-decl.h
+  td/actor/impl/EventFull.h
+  td/actor/impl/ConcurrentScheduler.h
+  td/actor/impl/Event.h
+  td/actor/impl/Scheduler-decl.h
+  td/actor/impl/Scheduler.h
+  td/actor/Condition.h
+  td/actor/MultiPromise.h
+  td/actor/PromiseFuture.h
+  td/actor/SchedulerLocalStorage.h
+  td/actor/SignalSlot.h
+  td/actor/SleepActor.h
+  td/actor/Timeout.h
+  td/actor/actor.h
+
+  td/actor/impl2/ActorLocker.h
+  td/actor/impl2/ActorSignals.h
+  td/actor/impl2/ActorState.h
+  td/actor/impl2/Scheduler.h
+  td/actor/impl2/SchedulerId.h
+)
+
+set(TDACTOR_TEST_SOURCE
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/actors_impl2.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/actors_main.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/actors_simple.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/actors_workers.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/actors_bugs.cpp
+  PARENT_SCOPE
+)
+
+#RULES
+
+#LIBRARIES
+
+add_library(tdactor STATIC ${TDACTOR_SOURCE})
+target_include_directories(tdactor PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>)
+target_link_libraries(tdactor PUBLIC tdutils)
+
+add_executable(example example/example.cpp)
+target_link_libraries(example PRIVATE tdactor)
+
+install(TARGETS tdactor EXPORT TdTargets
+  LIBRARY DESTINATION lib
+  ARCHIVE DESTINATION lib
+  RUNTIME DESTINATION bin
+  INCLUDES DESTINATION include
+)
diff --git a/libs/tdlib/td/tdactor/example/example.cpp b/libs/tdlib/td/tdactor/example/example.cpp
new file mode 100644
index 0000000000..4c2415c5e2
--- /dev/null
+++ b/libs/tdlib/td/tdactor/example/example.cpp
@@ -0,0 +1,49 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/actor/actor.h"
+
+#include "td/utils/logging.h"
+
+class Worker : public td::Actor {
+ public:
+  void ping(int x) {
+    LOG(ERROR) << "got ping " << x;
+  }
+};
+
+class MainActor : public td::Actor {
+ public:
+  void start_up() override {
+    LOG(ERROR) << "start up";
+    set_timeout_in(10);
+    worker_ = td::create_actor_on_scheduler<Worker>("Worker", 1);
+    send_closure(worker_, &Worker::ping, 123);
+  }
+
+  void timeout_expired() override {
+    LOG(ERROR) << "timeout expired";
+    td::Scheduler::instance()->finish();
+  }
+
+ private:
+  td::ActorOwn<Worker> worker_;
+};
+
+int main(void) {
+  td::ConcurrentScheduler scheduler;
+  scheduler.init(4 /*threads_count*/);
+  scheduler.start();
+  {
+    auto guard = scheduler.get_current_guard();
+    td::create_actor_on_scheduler<MainActor>("Main actor", 0).release();
+  }
+  while (!scheduler.is_finished()) {
+    scheduler.run_main(10);
+  }
+  scheduler.finish();
+  return 0;
+}
diff --git a/libs/tdlib/td/tdactor/td/actor/Condition.h b/libs/tdlib/td/tdactor/td/actor/Condition.h
new file mode 100644
index 0000000000..c3799df487
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/Condition.h
@@ -0,0 +1,47 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+
+#include "td/utils/logging.h"
+
+namespace td {
+class Condition {
+  class Helper : public Actor {
+   public:
+    void wait(Promise<> promise) {
+      pending_promises_.push_back(std::move(promise));
+    }
+
+   private:
+    std::vector<Promise<>> pending_promises_;
+    void tear_down() override {
+      for (auto &promise : pending_promises_) {
+        promise.set_value(Unit());
+      }
+    }
+  };
+
+ public:
+  Condition() {
+    own_actor_ = create_actor<Helper>("helper");
+    actor_ = own_actor_.get();
+  }
+  void wait(Promise<> promise) {
+    send_closure(actor_, &Helper::wait, std::move(promise));
+  }
+  void set_true() {
+    CHECK(!own_actor_.empty());
+    own_actor_.reset();
+  }
+
+ private:
+  ActorId<Helper> actor_;
+  ActorOwn<Helper> own_actor_;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/MultiPromise.cpp b/libs/tdlib/td/tdactor/td/actor/MultiPromise.cpp
new file mode 100644
index 0000000000..0d98f5cfb4
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/MultiPromise.cpp
@@ -0,0 +1,90 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/actor/MultiPromise.h"
+
+namespace td {
+void MultiPromiseActor::add_promise(Promise<Unit> &&promise) {
+  promises_.emplace_back(std::move(promise));
+}
+
+Promise<Unit> MultiPromiseActor::get_promise() {
+  if (empty()) {
+    register_actor("MultiPromise", this).release();
+  }
+  CHECK(!promises_.empty());
+
+  PromiseActor<Unit> promise;
+  FutureActor<Unit> future;
+  init_promise_future(&promise, &future);
+
+  future.set_event(EventCreator::raw(actor_id(), nullptr));
+  futures_.emplace_back(std::move(future));
+  return PromiseCreator::from_promise_actor(std::move(promise));
+}
+
+void MultiPromiseActor::raw_event(const Event::Raw &event) {
+  received_results_++;
+  if (received_results_ == futures_.size()) {
+    if (!ignore_errors_) {
+      for (auto &future : futures_) {
+        auto result = future.move_as_result();
+        if (result.is_error()) {
+          return set_result(result.move_as_error());
+        }
+      }
+    }
+    return set_result(Unit());
+  }
+}
+
+void MultiPromiseActor::set_ignore_errors(bool ignore_errors) {
+  ignore_errors_ = ignore_errors;
+}
+
+void MultiPromiseActor::set_result(Result<Unit> &&result) {
+  // MultiPromiseActor should be cleared before he begins to send out result
+  auto promises_copy = std::move(promises_);
+  promises_.clear();
+  auto futures_copy = std::move(futures_);
+  futures_.clear();
+  received_results_ = 0;
+  stop();
+
+  if (!promises_copy.empty()) {
+    for (size_t i = 0; i + 1 < promises_copy.size(); i++) {
+      promises_copy[i].set_result(result.clone());
+    }
+    promises_copy.back().set_result(std::move(result));
+  }
+}
+
+size_t MultiPromiseActor::promise_count() const {
+  return promises_.size();
+}
+
+void MultiPromiseActorSafe::add_promise(Promise<Unit> &&promise) {
+  multi_promise_->add_promise(std::move(promise));
+}
+
+Promise<Unit> MultiPromiseActorSafe::get_promise() {
+  return multi_promise_->get_promise();
+}
+
+void MultiPromiseActorSafe::set_ignore_errors(bool ignore_errors) {
+  multi_promise_->set_ignore_errors(ignore_errors);
+}
+
+size_t MultiPromiseActorSafe::promise_count() const {
+  return multi_promise_->promise_count();
+}
+
+MultiPromiseActorSafe::~MultiPromiseActorSafe() {
+  if (!multi_promise_->empty()) {
+    register_existing_actor(std::move(multi_promise_)).release();
+  }
+}
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/MultiPromise.h b/libs/tdlib/td/tdactor/td/actor/MultiPromise.h
new file mode 100644
index 0000000000..aa28947464
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/MultiPromise.h
@@ -0,0 +1,116 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+class MultiPromiseInterface {
+ public:
+  virtual void add_promise(Promise<> &&promise) = 0;
+  virtual Promise<> get_promise() = 0;
+
+  // deprecated?
+  virtual size_t promise_count() const = 0;
+  virtual void set_ignore_errors(bool ignore_errors) = 0;
+
+  MultiPromiseInterface() = default;
+  MultiPromiseInterface(const MultiPromiseInterface &) = delete;
+  MultiPromiseInterface &operator=(const MultiPromiseInterface &) = delete;
+  MultiPromiseInterface(MultiPromiseInterface &&) = default;
+  MultiPromiseInterface &operator=(MultiPromiseInterface &&) = default;
+  virtual ~MultiPromiseInterface() = default;
+};
+
+class MultiPromise : public MultiPromiseInterface {
+ public:
+  void add_promise(Promise<> &&promise) override {
+    impl_->add_promise(std::move(promise));
+  }
+  Promise<> get_promise() override {
+    return impl_->get_promise();
+  }
+
+  // deprecated?
+  size_t promise_count() const override {
+    return impl_->promise_count();
+  }
+  void set_ignore_errors(bool ignore_errors) override {
+    impl_->set_ignore_errors(ignore_errors);
+  }
+
+  MultiPromise() = default;
+  explicit MultiPromise(std::unique_ptr<MultiPromiseInterface> impl) : impl_(std::move(impl)) {
+  }
+
+ private:
+  std::unique_ptr<MultiPromiseInterface> impl_;
+};
+
+class MultiPromiseActor final
+    : public Actor
+    , public MultiPromiseInterface {
+ public:
+  MultiPromiseActor() = default;
+
+  void add_promise(Promise<Unit> &&promise) override;
+
+  Promise<Unit> get_promise() override;
+
+  void set_ignore_errors(bool ignore_errors) override;
+
+  size_t promise_count() const override;
+
+ private:
+  void set_result(Result<Unit> &&result);
+
+  vector<Promise<Unit>> promises_;     // promises waiting for result
+  vector<FutureActor<Unit>> futures_;  // futures waiting for result of the queries
+  size_t received_results_ = 0;
+  bool ignore_errors_ = false;
+
+  void raw_event(const Event::Raw &event) override;
+
+  void on_start_migrate(int32) override {
+    UNREACHABLE();
+  }
+  void on_finish_migrate() override {
+    UNREACHABLE();
+  }
+};
+
+class MultiPromiseActorSafe : public MultiPromiseInterface {
+ public:
+  void add_promise(Promise<Unit> &&promise) override;
+  Promise<Unit> get_promise() override;
+  void set_ignore_errors(bool ignore_errors) override;
+  size_t promise_count() const override;
+  MultiPromiseActorSafe() = default;
+  MultiPromiseActorSafe(const MultiPromiseActorSafe &other) = delete;
+  MultiPromiseActorSafe &operator=(const MultiPromiseActorSafe &other) = delete;
+  MultiPromiseActorSafe(MultiPromiseActorSafe &&other) = delete;
+  MultiPromiseActorSafe &operator=(MultiPromiseActorSafe &&other) = delete;
+  ~MultiPromiseActorSafe() override;
+
+ private:
+  std::unique_ptr<MultiPromiseActor> multi_promise_ = std::make_unique<MultiPromiseActor>();
+};
+
+class MultiPromiseCreator {
+ public:
+  static MultiPromise create() {
+    return MultiPromise(std::make_unique<MultiPromiseActor>());
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/PromiseFuture.h b/libs/tdlib/td/tdactor/td/actor/PromiseFuture.h
new file mode 100644
index 0000000000..63156c3838
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/PromiseFuture.h
@@ -0,0 +1,570 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+
+#include "td/utils/Closure.h"
+#include "td/utils/common.h"
+#include "td/utils/invoke.h"  // for tuple_for_each
+#include "td/utils/logging.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Status.h"
+
+#include <tuple>
+#include <type_traits>
+#include <utility>
+
+namespace td {
+template <class T = Unit>
+class PromiseInterface {
+ public:
+  PromiseInterface() = default;
+  PromiseInterface(const PromiseInterface &) = delete;
+  PromiseInterface &operator=(const PromiseInterface &) = delete;
+  PromiseInterface(PromiseInterface &&) = default;
+  PromiseInterface &operator=(PromiseInterface &&) = default;
+  virtual ~PromiseInterface() = default;
+  virtual void set_value(T &&value) {
+    set_result(std::move(value));
+  }
+  virtual void set_error(Status &&error) {
+    set_result(std::move(error));
+  }
+  virtual void set_result(Result<T> &&result) {
+    if (result.is_ok()) {
+      set_value(result.move_as_ok());
+    } else {
+      set_error(result.move_as_error());
+    }
+  }
+  virtual void start_migrate(int32 sched_id) {
+  }
+  virtual void finish_migrate() {
+  }
+};
+
+template <class T = Unit>
+class FutureInterface {
+ public:
+  FutureInterface() = default;
+  FutureInterface(const FutureInterface &) = delete;
+  FutureInterface &operator=(const FutureInterface &) = delete;
+  FutureInterface(FutureInterface &&) = default;
+  FutureInterface &operator=(FutureInterface &&) = default;
+  virtual ~FutureInterface() = default;
+  virtual bool is_ready() = 0;
+  virtual bool is_ok() = 0;
+  virtual bool is_error() = 0;
+  virtual const T &ok() = 0;
+  virtual T move_as_ok() = 0;
+  virtual const Status &error() = 0;
+  virtual Status move_as_error() TD_WARN_UNUSED_RESULT = 0;
+  virtual const Result<T> &result() = 0;
+  virtual Result<T> move_as_result() TD_WARN_UNUSED_RESULT = 0;
+};
+
+template <class T>
+class SafePromise;
+
+template <class T = Unit>
+class Promise {
+ public:
+  void set_value(T &&value) {
+    if (!promise_) {
+      return;
+    }
+    promise_->set_value(std::move(value));
+    promise_.reset();
+  }
+  void set_error(Status &&error) {
+    if (!promise_) {
+      return;
+    }
+    promise_->set_error(std::move(error));
+    promise_.reset();
+  }
+  void set_result(Result<T> &&result) {
+    if (!promise_) {
+      return;
+    }
+    promise_->set_result(std::move(result));
+    promise_.reset();
+  }
+  void reset() {
+    promise_.reset();
+  }
+  void start_migrate(int32 sched_id) {
+    if (!promise_) {
+      return;
+    }
+    promise_->start_migrate(sched_id);
+  }
+  void finish_migrate() {
+    if (!promise_) {
+      return;
+    }
+    promise_->finish_migrate();
+  }
+  std::unique_ptr<PromiseInterface<T>> release() {
+    return std::move(promise_);
+  }
+
+  Promise() = default;
+  explicit Promise(std::unique_ptr<PromiseInterface<T>> promise) : promise_(std::move(promise)) {
+  }
+  Promise(SafePromise<T> &&other);
+  Promise &operator=(SafePromise<T> &&other);
+
+  explicit operator bool() {
+    return static_cast<bool>(promise_);
+  }
+
+ private:
+  std::unique_ptr<PromiseInterface<T>> promise_;
+};
+
+template <class T>
+void start_migrate(Promise<T> &promise, int32 sched_id) {
+  // promise.start_migrate(sched_id);
+}
+template <class T>
+void finish_migrate(Promise<T> &promise) {
+  // promise.finish_migrate();
+}
+
+template <class T = Unit>
+class SafePromise {
+ public:
+  SafePromise(Promise<T> promise, Result<T> result) : promise_(std::move(promise)), result_(std::move(result)) {
+  }
+  SafePromise(const SafePromise &other) = delete;
+  SafePromise &operator=(const SafePromise &other) = delete;
+  SafePromise(SafePromise &&other) = default;
+  SafePromise &operator=(SafePromise &&other) = default;
+  ~SafePromise() {
+    if (promise_) {
+      promise_.set_result(std::move(result_));
+    }
+  }
+  Promise<T> release() {
+    return std::move(promise_);
+  }
+
+ private:
+  Promise<T> promise_;
+  Result<T> result_;
+};
+
+template <class T>
+Promise<T>::Promise(SafePromise<T> &&other) : Promise(other.release()) {
+}
+template <class T>
+Promise<T> &Promise<T>::operator=(SafePromise<T> &&other) {
+  *this = other.release();
+  return *this;
+}
+
+namespace detail {
+
+class EventPromise : public PromiseInterface<Unit> {
+ public:
+  void set_value(Unit &&) override {
+    ok_.try_emit();
+    fail_.clear();
+  }
+  void set_error(Status &&) override {
+    do_set_error();
+  }
+
+  EventPromise(const EventPromise &other) = delete;
+  EventPromise &operator=(const EventPromise &other) = delete;
+  EventPromise(EventPromise &&other) = delete;
+  EventPromise &operator=(EventPromise &&other) = delete;
+  ~EventPromise() override {
+    do_set_error();
+  }
+
+  EventPromise() = default;
+  explicit EventPromise(EventFull ok) : ok_(std::move(ok)), use_ok_as_fail_(true) {
+  }
+  EventPromise(EventFull ok, EventFull fail) : ok_(std::move(ok)), fail_(std::move(fail)), use_ok_as_fail_(false) {
+  }
+
+ private:
+  EventFull ok_;
+  EventFull fail_;
+  bool use_ok_as_fail_ = false;
+  void do_set_error() {
+    if (use_ok_as_fail_) {
+      ok_.try_emit();
+    } else {
+      ok_.clear();
+      fail_.try_emit();
+    }
+  }
+};
+
+template <typename T>
+struct GetArg : public GetArg<decltype(&T::operator())> {};
+
+template <class C, class R, class Arg>
+class GetArg<R (C::*)(Arg)> {
+ public:
+  using type = Arg;
+};
+template <class C, class R, class Arg>
+class GetArg<R (C::*)(Arg) const> {
+ public:
+  using type = Arg;
+};
+
+template <class T>
+using get_arg_t = std::decay_t<typename GetArg<T>::type>;
+
+template <class T>
+struct DropResult {
+  using type = T;
+};
+
+template <class T>
+struct DropResult<Result<T>> {
+  using type = T;
+};
+
+template <class T>
+using drop_result_t = typename DropResult<T>::type;
+
+template <class ValueT, class FunctionOkT, class FunctionFailT>
+class LambdaPromise : public PromiseInterface<ValueT> {
+  enum OnFail { None, Ok, Fail };
+
+ public:
+  void set_value(ValueT &&value) override {
+    ok_(std::move(value));
+    on_fail_ = None;
+  }
+  void set_error(Status &&error) override {
+    do_error(std::move(error));
+  }
+  LambdaPromise(const LambdaPromise &other) = delete;
+  LambdaPromise &operator=(const LambdaPromise &other) = delete;
+  LambdaPromise(LambdaPromise &&other) = delete;
+  LambdaPromise &operator=(LambdaPromise &&other) = delete;
+  ~LambdaPromise() override {
+    do_error(Status::Error("Lost promise"));
+  }
+
+  template <class FromOkT, class FromFailT>
+  LambdaPromise(FromOkT &&ok, FromFailT &&fail, bool use_ok_as_fail)
+      : ok_(std::forward<FromOkT>(ok)), fail_(std::forward<FromFailT>(fail)), on_fail_(use_ok_as_fail ? Ok : Fail) {
+  }
+
+ private:
+  FunctionOkT ok_;
+  FunctionFailT fail_;
+  OnFail on_fail_ = None;
+
+  template <class FuncT, class ArgT = detail::get_arg_t<FuncT>>
+  std::enable_if_t<std::is_assignable<ArgT, Status>::value> do_error_impl(FuncT &func, Status &&status) {
+    func(std::move(status));
+  }
+
+  template <class FuncT, class ArgT = detail::get_arg_t<FuncT>>
+  std::enable_if_t<!std::is_assignable<ArgT, Status>::value> do_error_impl(FuncT &func, Status &&status) {
+    func(Auto());
+  }
+
+  void do_error(Status &&error) {
+    switch (on_fail_) {
+      case None:
+        break;
+      case Ok:
+        do_error_impl(ok_, std::move(error));
+        break;
+      case Fail:
+        fail_(std::move(error));
+        break;
+    }
+    on_fail_ = None;
+  }
+};
+
+template <class... ArgsT>
+class JoinPromise : public PromiseInterface<Unit> {
+ public:
+  explicit JoinPromise(ArgsT &&... arg) : promises_(std::forward<ArgsT>(arg)...) {
+  }
+  void set_value(Unit &&) override {
+    tuple_for_each(promises_, [](auto &promise) { promise.set_value(Unit()); });
+  }
+  void set_error(Status &&error) override {
+    tuple_for_each(promises_, [&error](auto &promise) { promise.set_error(error.clone()); });
+  }
+
+ private:
+  std::tuple<std::decay_t<ArgsT>...> promises_;
+};
+}  // namespace detail
+
+/*** FutureActor and PromiseActor ***/
+template <class T>
+class FutureActor;
+
+template <class T>
+class PromiseActor;
+
+template <class T>
+class ActorTraits<FutureActor<T>> {
+ public:
+  static constexpr bool is_lite = true;
+};
+
+template <class T>
+class PromiseActor final : public PromiseInterface<T> {
+  friend class FutureActor<T>;
+  enum State { Waiting, Hangup };
+
+ public:
+  PromiseActor() = default;
+  PromiseActor(const PromiseActor &other) = delete;
+  PromiseActor &operator=(const PromiseActor &other) = delete;
+  PromiseActor(PromiseActor &&) = default;
+  PromiseActor &operator=(PromiseActor &&) = default;
+  ~PromiseActor() override {
+    close();
+  }
+
+  void set_value(T &&value) override;
+  void set_error(Status &&error) override;
+
+  void close() {
+    future_id_.reset();
+  }
+
+  // NB: if true is returned no further events will be sent
+  bool is_hangup() {
+    if (state_ == State::Hangup) {
+      return true;
+    }
+    if (!future_id_.is_alive()) {
+      state_ = State::Hangup;
+      future_id_.release();
+      event_.clear();
+      return true;
+    }
+    return false;
+  }
+
+  template <class S>
+  friend void init_promise_future(PromiseActor<S> *promise, FutureActor<S> *future);
+
+  bool empty_promise() {
+    return future_id_.empty();
+  }
+  bool empty() {
+    return future_id_.empty();
+  }
+
+ private:
+  ActorOwn<FutureActor<T>> future_id_;
+  EventFull event_;
+  State state_;
+
+  void init() {
+    state_ = State::Waiting;
+    event_.clear();
+  }
+};
+
+template <class T>
+class FutureActor final : public Actor {
+  friend class PromiseActor<T>;
+  enum State { Waiting, Ready };
+
+ public:
+  FutureActor() = default;
+
+  FutureActor(const FutureActor &other) = delete;
+  FutureActor &operator=(const FutureActor &other) = delete;
+
+  FutureActor(FutureActor &&other) = default;
+  FutureActor &operator=(FutureActor &&other) = default;
+
+  ~FutureActor() override = default;
+
+  bool is_ok() const {
+    return is_ready() && result_.is_ok();
+  }
+  bool is_error() const {
+    CHECK(is_ready());
+    return is_ready() && result_.is_error();
+  }
+  T move_as_ok() {
+    return move_as_result().move_as_ok();
+  }
+  Status move_as_error() TD_WARN_UNUSED_RESULT {
+    return move_as_result().move_as_error();
+  }
+  Result<T> move_as_result() TD_WARN_UNUSED_RESULT {
+    CHECK(is_ready());
+    SCOPE_EXIT {
+      do_stop();
+    };
+    return std::move(result_);
+  }
+  bool is_ready() const {
+    return !empty() && state_ == State::Ready;
+  }
+
+  void close() {
+    event_.clear();
+    result_.clear();
+    do_stop();
+  }
+
+  void set_event(EventFull &&event) {
+    CHECK(!empty());
+    event_ = std::move(event);
+    if (state_ != State::Waiting) {
+      event_.try_emit_later();
+    }
+  }
+
+  template <class S>
+  friend void init_promise_future(PromiseActor<S> *promise, FutureActor<S> *future);
+
+ private:
+  EventFull event_;
+  Result<T> result_;
+  State state_;
+
+  void set_value(T &&value) {
+    set_result(std::move(value));
+  }
+
+  void set_error(Status &&error) {
+    set_result(std::move(error));
+  }
+
+  void set_result(Result<T> &&result) {
+    CHECK(state_ == State::Waiting);
+    result_ = std::move(result);
+    state_ = State::Ready;
+
+    event_.try_emit_later();
+  }
+
+  void hangup() override {
+    set_error(Status::Hangup());
+  }
+
+  void start_up() override {
+    // empty
+  }
+
+  void init() {
+    CHECK(empty());
+    state_ = State::Waiting;
+    event_.clear();
+  }
+};
+
+template <class T>
+void PromiseActor<T>::set_value(T &&value) {
+  if (state_ == State::Waiting && !future_id_.empty()) {
+    send_closure(std::move(future_id_), &FutureActor<T>::set_value, std::move(value));
+  }
+}
+template <class T>
+void PromiseActor<T>::set_error(Status &&error) {
+  if (state_ == State::Waiting && !future_id_.empty()) {
+    send_closure(std::move(future_id_), &FutureActor<T>::set_error, std::move(error));
+  }
+}
+
+template <class S>
+void init_promise_future(PromiseActor<S> *promise, FutureActor<S> *future) {
+  promise->init();
+  future->init();
+  promise->future_id_ = register_actor("FutureActor", future);
+
+  CHECK(future->get_info() != nullptr);
+}
+
+template <class T>
+class PromiseFuture {
+ public:
+  PromiseFuture() {
+    init_promise_future(&promise_, &future_);
+  }
+  PromiseActor<T> &promise() {
+    return promise_;
+  }
+  FutureActor<T> &future() {
+    return future_;
+  }
+  PromiseActor<T> &&move_promise() {
+    return std::move(promise_);
+  }
+  FutureActor<T> &&move_future() {
+    return std::move(future_);
+  }
+
+ private:
+  PromiseActor<T> promise_;
+  FutureActor<T> future_;
+};
+
+template <class T, class ActorAT, class ActorBT, class ResultT, class... DestArgsT, class... ArgsT>
+FutureActor<T> send_promise(ActorId<ActorAT> actor_id, Send::Flags flags,
+                            ResultT (ActorBT::*func)(PromiseActor<T> &&, DestArgsT...), ArgsT &&... args) {
+  PromiseFuture<T> pf;
+  ::td::Scheduler::instance()->send_closure(
+      std::move(actor_id), create_immediate_closure(func, pf.move_promise(), std::forward<ArgsT>(args)...), flags);
+  return pf.move_future();
+}
+
+class PromiseCreator {
+ public:
+  struct Ignore {
+    void operator()(Status &&error) {
+      error.ignore();
+    }
+  };
+
+  template <class OkT, class ArgT = detail::drop_result_t<detail::get_arg_t<OkT>>>
+  static Promise<ArgT> lambda(OkT &&ok) {
+    return Promise<ArgT>(std::make_unique<detail::LambdaPromise<ArgT, std::decay_t<OkT>, Ignore>>(std::forward<OkT>(ok),
+                                                                                                  Ignore(), true));
+  }
+
+  template <class OkT, class FailT, class ArgT = detail::get_arg_t<OkT>>
+  static Promise<ArgT> lambda(OkT &&ok, FailT &&fail) {
+    return Promise<ArgT>(std::make_unique<detail::LambdaPromise<ArgT, std::decay_t<OkT>, std::decay_t<FailT>>>(
+        std::forward<OkT>(ok), std::forward<FailT>(fail), false));
+  }
+
+  static Promise<> event(EventFull &&ok) {
+    return Promise<>(std::make_unique<detail::EventPromise>(std::move(ok)));
+  }
+
+  static Promise<> event(EventFull ok, EventFull fail) {
+    return Promise<>(std::make_unique<detail::EventPromise>(std::move(ok), std::move(fail)));
+  }
+
+  template <class... ArgsT>
+  static Promise<> join(ArgsT &&... args) {
+    return Promise<>(std::make_unique<detail::JoinPromise<ArgsT...>>(std::forward<ArgsT>(args)...));
+  }
+
+  template <class T>
+  static Promise<T> from_promise_actor(PromiseActor<T> &&from) {
+    return Promise<T>(std::make_unique<PromiseActor<T>>(std::move(from)));
+  }
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/SchedulerLocalStorage.h b/libs/tdlib/td/tdactor/td/actor/SchedulerLocalStorage.h
new file mode 100644
index 0000000000..f505836a16
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/SchedulerLocalStorage.h
@@ -0,0 +1,70 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/optional.h"
+
+#include <functional>
+
+namespace td {
+template <class T>
+class SchedulerLocalStorage {
+ public:
+  SchedulerLocalStorage() : data_(Scheduler::instance()->sched_count()) {
+  }
+  T &get() {
+    return data_[Scheduler::instance()->sched_id()];
+  }
+  template <class F>
+  void for_each(F &&f) {
+    for (auto &value : data_) {
+      f(value);
+    }
+  }
+  template <class F>
+  void for_each(F &&f) const {
+    for (const auto &value : data_) {
+      f(value);
+    }
+  }
+
+ private:
+  std::vector<T> data_;
+};
+
+template <class T>
+class LazySchedulerLocalStorage {
+ public:
+  LazySchedulerLocalStorage() = default;
+  explicit LazySchedulerLocalStorage(std::function<T()> create_func) : create_func_(std::move(create_func)) {
+  }
+
+  T &get() {
+    auto &optional_value_ = sls_optional_value_.get();
+    if (!optional_value_) {
+      CHECK(create_func_);
+      optional_value_ = create_func_();
+    }
+    return *optional_value_;
+  }
+  void clear_values() {
+    sls_optional_value_.for_each([&](auto &optional_value) {
+      if (optional_value) {
+        optional_value = optional<T>();
+      }
+    });
+  }
+
+ private:
+  std::function<T()> create_func_;
+  SchedulerLocalStorage<optional<T>> sls_optional_value_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/SignalSlot.h b/libs/tdlib/td/tdactor/td/actor/SignalSlot.h
new file mode 100644
index 0000000000..73b48f58ed
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/SignalSlot.h
@@ -0,0 +1,108 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+
+namespace td {
+class Slot;
+class Signal {
+ public:
+  void emit();
+
+  explicit Signal(ActorId<Slot> slot_id) : slot_id_(slot_id) {
+  }
+
+ private:
+  ActorId<Slot> slot_id_;
+};
+class Slot final : public Actor {
+ public:
+  Slot() = default;
+  Slot(const Slot &other) = delete;
+  Slot &operator=(const Slot &other) = delete;
+  Slot(Slot &&) = default;
+  Slot &operator=(Slot &&) = default;
+  ~Slot() override {
+    close();
+  }
+  void set_event(EventFull &&event) {
+    was_signal_ = false;
+    event_ = std::move(event);
+  }
+
+  bool has_event() {
+    return !event_.empty();
+  }
+
+  bool was_signal() {
+    return was_signal_;
+  }
+
+  void clear_event() {
+    event_.clear();
+  }
+
+  void close() {
+    if (!empty()) {
+      do_stop();
+    }
+  }
+
+  void set_timeout_in(double timeout_in) {
+    register_if_empty();
+    Actor::set_timeout_in(timeout_in);
+  }
+  void set_timeout_at(double timeout_at) {
+    register_if_empty();
+    Actor::set_timeout_at(timeout_at);
+  }
+
+  friend class Signal;
+  Signal get_signal() {
+    register_if_empty();
+    return Signal(actor_id(this));
+  }
+  ActorShared<> get_signal_new() {
+    register_if_empty();
+    return actor_shared();
+  }
+
+ private:
+  bool was_signal_ = false;
+  EventFull event_;
+
+  void timeout_expired() override {
+    signal();
+  }
+
+  void start_up() override {
+    empty();
+  }
+
+  void register_if_empty() {
+    if (empty()) {
+      register_actor("Slot", this).release();
+    }
+  }
+
+  // send event only once
+  void signal() {
+    if (!was_signal_) {
+      was_signal_ = true;
+      event_.try_emit_later();
+    }
+  }
+  void hangup_shared() override {
+    signal();
+  }
+};
+inline void Signal::emit() {
+  send_closure(slot_id_, &Slot::signal);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/SleepActor.h b/libs/tdlib/td/tdactor/td/actor/SleepActor.h
new file mode 100644
index 0000000000..9b9981ec38
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/SleepActor.h
@@ -0,0 +1,33 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+
+#include "td/actor/PromiseFuture.h"
+
+namespace td {
+
+class SleepActor : public Actor {
+ public:
+  SleepActor(double timeout, Promise<> promise) : timeout_(timeout), promise_(std::move(promise)) {
+  }
+
+ private:
+  double timeout_;
+  Promise<> promise_;
+
+  void start_up() override {
+    set_timeout_in(timeout_);
+  }
+  void timeout_expired() override {
+    promise_.set_value(Unit());
+    stop();
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/Timeout.cpp b/libs/tdlib/td/tdactor/td/actor/Timeout.cpp
new file mode 100644
index 0000000000..fa2e5ffff3
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/Timeout.cpp
@@ -0,0 +1,96 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/actor/Timeout.h"
+
+#include "td/utils/Time.h"
+
+namespace td {
+
+bool MultiTimeout::has_timeout(int64 key) const {
+  return items_.find(Item(key)) != items_.end();
+}
+
+void MultiTimeout::set_timeout_at(int64 key, double timeout) {
+  LOG(DEBUG) << "Set timeout for " << key << " in " << timeout - Time::now();
+  auto item = items_.emplace(key);
+  auto heap_node = static_cast<HeapNode *>(const_cast<Item *>(&*item.first));
+  if (heap_node->in_heap()) {
+    CHECK(!item.second);
+    bool need_update_timeout = heap_node->is_top();
+    timeout_queue_.fix(timeout, heap_node);
+    if (need_update_timeout || heap_node->is_top()) {
+      update_timeout();
+    }
+  } else {
+    CHECK(item.second);
+    timeout_queue_.insert(timeout, heap_node);
+    if (heap_node->is_top()) {
+      update_timeout();
+    }
+  }
+}
+
+void MultiTimeout::add_timeout_at(int64 key, double timeout) {
+  LOG(DEBUG) << "Add timeout for " << key << " in " << timeout - Time::now();
+  auto item = items_.emplace(key);
+  auto heap_node = static_cast<HeapNode *>(const_cast<Item *>(&*item.first));
+  if (heap_node->in_heap()) {
+    CHECK(!item.second);
+  } else {
+    CHECK(item.second);
+    timeout_queue_.insert(timeout, heap_node);
+    if (heap_node->is_top()) {
+      update_timeout();
+    }
+  }
+}
+
+void MultiTimeout::cancel_timeout(int64 key) {
+  LOG(DEBUG) << "Cancel timeout for " << key;
+  auto item = items_.find(Item(key));
+  if (item != items_.end()) {
+    auto heap_node = static_cast<HeapNode *>(const_cast<Item *>(&*item));
+    CHECK(heap_node->in_heap());
+    bool need_update_timeout = heap_node->is_top();
+    timeout_queue_.erase(heap_node);
+    items_.erase(item);
+
+    if (need_update_timeout) {
+      update_timeout();
+    }
+  }
+}
+
+void MultiTimeout::update_timeout() {
+  if (items_.empty()) {
+    LOG(DEBUG) << "Cancel timeout";
+    CHECK(timeout_queue_.empty());
+    CHECK(Actor::has_timeout());
+    Actor::cancel_timeout();
+  } else {
+    LOG(DEBUG) << "Set timeout in " << timeout_queue_.top_key() - Time::now_cached();
+    Actor::set_timeout_at(timeout_queue_.top_key());
+  }
+}
+
+void MultiTimeout::timeout_expired() {
+  double now = Time::now_cached();
+  while (!timeout_queue_.empty() && timeout_queue_.top_key() < now) {
+    int64 key = static_cast<Item *>(timeout_queue_.pop())->key;
+    items_.erase(Item(key));
+    expired_.push_back(key);
+  }
+  if (!items_.empty()) {
+    update_timeout();
+  }
+  for (auto key : expired_) {
+    callback_(data_, key);
+  }
+  expired_.clear();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/Timeout.h b/libs/tdlib/td/tdactor/td/actor/Timeout.h
new file mode 100644
index 0000000000..a3a9ba1913
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/Timeout.h
@@ -0,0 +1,127 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+
+#include "td/utils/Heap.h"
+#include "td/utils/logging.h"
+#include "td/utils/Time.h"
+
+#include <set>
+
+namespace td {
+class Timeout final : public Actor {
+ public:
+  using Data = void *;
+  using Callback = void (*)(Data);
+  Timeout() {
+    register_actor("Timeout", this).release();
+  }
+
+  void set_callback(Callback callback) {
+    callback_ = callback;
+  }
+  void set_callback_data(Data &&data) {
+    data_ = data;
+  }
+
+  bool has_timeout() const {
+    return Actor::has_timeout();
+  }
+  void set_timeout_in(double timeout) {
+    Actor::set_timeout_in(timeout);
+  }
+  void cancel_timeout() {
+    if (has_timeout()) {
+      Actor::cancel_timeout();
+      callback_ = Callback();
+      data_ = Data();
+    }
+  }
+
+ private:
+  friend class Scheduler;
+
+  Callback callback_;
+  Data data_;
+
+  void set_timeout_at(double timeout) {
+    Actor::set_timeout_at(timeout);
+  }
+
+  void timeout_expired() override {
+    CHECK(!has_timeout());
+    CHECK(callback_ != Callback());
+    Callback callback = callback_;
+    Data data = data_;
+    callback_ = Callback();
+    data_ = Data();
+
+    callback(data);
+  }
+};
+
+// TODO optimize
+class MultiTimeout final : public Actor {
+  struct Item : public HeapNode {
+    int64 key;
+
+    explicit Item(int64 key) : key(key) {
+    }
+
+    bool operator<(const Item &other) const {
+      return key < other.key;
+    }
+  };
+
+ public:
+  using Data = void *;
+  using Callback = void (*)(Data, int64);
+  MultiTimeout() {
+    register_actor("MultiTimeout", this).release();
+  }
+
+  void set_callback(Callback callback) {
+    callback_ = callback;
+  }
+  void set_callback_data(Data data) {
+    data_ = data;
+  }
+
+  bool has_timeout(int64 key) const;
+
+  void set_timeout_in(int64 key, double timeout) {
+    set_timeout_at(key, Time::now() + timeout);
+  }
+
+  void add_timeout_in(int64 key, double timeout) {
+    add_timeout_at(key, Time::now() + timeout);
+  }
+
+  void set_timeout_at(int64 key, double timeout);
+
+  void add_timeout_at(int64 key, double timeout);  // memcache semantics, doesn't replace old timeout
+
+  void cancel_timeout(int64 key);
+
+ private:
+  friend class Scheduler;
+
+  Callback callback_;
+  Data data_;
+
+  KHeap<double> timeout_queue_;
+  std::set<Item> items_;
+  std::vector<int64> expired_;
+
+  void update_timeout();
+
+  void timeout_expired() override;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/actor.h b/libs/tdlib/td/tdactor/td/actor/actor.h
new file mode 100644
index 0000000000..dadfadc055
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/actor.h
@@ -0,0 +1,14 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/impl/Actor.h"
+#include "td/actor/impl/ActorId.h"
+#include "td/actor/impl/ActorInfo.h"
+#include "td/actor/impl/ConcurrentScheduler.h"
+#include "td/actor/impl/EventFull.h"
+#include "td/actor/impl/Scheduler.h"
diff --git a/libs/tdlib/td/tdactor/td/actor/impl/Actor-decl.h b/libs/tdlib/td/tdactor/td/actor/impl/Actor-decl.h
new file mode 100644
index 0000000000..4342214800
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl/Actor-decl.h
@@ -0,0 +1,120 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/impl/ActorId-decl.h"
+#include "td/actor/impl/ActorInfo-decl.h"
+#include "td/actor/impl/Event.h"
+
+#include "td/utils/ObjectPool.h"
+#include "td/utils/Observer.h"
+#include "td/utils/Slice.h"
+
+#include <memory>
+
+namespace td {
+
+class Actor : public ObserverBase {
+ public:
+  using Deleter = ActorInfo::Deleter;
+  Actor() = default;
+  Actor(const Actor &) = delete;
+  Actor &operator=(const Actor &) = delete;
+  Actor(Actor &&other);
+  Actor &operator=(Actor &&other);
+  ~Actor() override {
+    if (!empty()) {
+      do_stop();
+    }
+  }
+
+  virtual void start_up() {
+    yield();
+  }
+  virtual void tear_down() {
+  }
+  virtual void wakeup() {
+    loop();
+  }
+  virtual void hangup() {
+    stop();
+  }
+  virtual void hangup_shared() {
+    // ignore
+  }
+  virtual void timeout_expired() {
+    loop();
+  }
+  virtual void raw_event(const Event::Raw &event) {
+  }
+  virtual void loop() {
+  }
+
+  // TODO: not called in events. Can't use stop, or migrate inside of them
+  virtual void on_start_migrate(int32 sched_id) {
+  }
+  virtual void on_finish_migrate() {
+  }
+
+  void notify() override;
+
+  // proxy to scheduler
+  void yield();
+  void stop();
+  void do_stop();
+  bool has_timeout() const;
+  void set_timeout_in(double timeout_in);
+  void set_timeout_at(double timeout_at);
+  void cancel_timeout();
+  void migrate(int32 sched_id);
+  void do_migrate(int32 sched_id);
+
+  uint64 get_link_token();
+  void set_context(std::shared_ptr<ActorContext> context);
+  void set_tag(CSlice tag);
+
+  void always_wait_for_mailbox();
+
+  // for ActorInfo mostly
+  void init(ObjectPool<ActorInfo>::OwnerPtr &&info);
+  ActorInfo *get_info();
+  const ActorInfo *get_info() const;
+  ObjectPool<ActorInfo>::OwnerPtr clear();
+
+  bool empty() const;
+
+  template <class FuncT, class... ArgsT>
+  auto self_closure(FuncT &&func, ArgsT &&... args);
+
+  template <class SelfT, class FuncT, class... ArgsT>
+  auto self_closure(SelfT *self, FuncT &&func, ArgsT &&... args);
+
+  template <class LambdaT>
+  auto self_lambda(LambdaT &&lambda);
+
+  // proxy to info_
+  ActorId<> actor_id();
+  template <class SelfT>
+  ActorId<SelfT> actor_id(SelfT *self);
+
+  ActorShared<> actor_shared();
+  template <class SelfT>
+  ActorShared<SelfT> actor_shared(SelfT *self, uint64 id = static_cast<uint64>(-1));
+
+  Slice get_name() const;
+
+ private:
+  ObjectPool<ActorInfo>::OwnerPtr info_;
+};
+
+template <class ActorT>
+class ActorTraits {
+ public:
+  static constexpr bool is_lite = false;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl/Actor.h b/libs/tdlib/td/tdactor/td/actor/impl/Actor.h
new file mode 100644
index 0000000000..3fe5e20abf
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl/Actor.h
@@ -0,0 +1,153 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/impl/Actor-decl.h"
+#include "td/actor/impl/EventFull-decl.h"
+#include "td/actor/impl/Scheduler-decl.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/ObjectPool.h"
+#include "td/utils/Slice.h"
+
+#include <memory>
+#include <type_traits>
+#include <utility>
+
+namespace td {
+inline Actor::Actor(Actor &&other) {
+  CHECK(info_.empty());
+  info_ = std::move(other.info_);
+  if (!empty()) {
+    info_->on_actor_moved(this);
+  }
+}
+inline Actor &Actor::operator=(Actor &&other) {
+  CHECK(info_.empty());
+  info_ = std::move(other.info_);
+  if (!empty()) {
+    info_->on_actor_moved(this);
+  }
+  return *this;
+}
+
+inline void Actor::notify() {
+  yield();
+}
+
+// proxy to scheduler
+inline void Actor::yield() {
+  Scheduler::instance()->yield_actor(this);
+}
+inline void Actor::stop() {
+  Scheduler::instance()->stop_actor(this);
+}
+inline void Actor::do_stop() {
+  Scheduler::instance()->do_stop_actor(this);
+  CHECK(empty());
+}
+inline bool Actor::has_timeout() const {
+  return Scheduler::instance()->has_actor_timeout(this);
+}
+inline void Actor::set_timeout_in(double timeout_in) {
+  Scheduler::instance()->set_actor_timeout_in(this, timeout_in);
+}
+inline void Actor::set_timeout_at(double timeout_at) {
+  Scheduler::instance()->set_actor_timeout_at(this, timeout_at);
+}
+inline void Actor::cancel_timeout() {
+  Scheduler::instance()->cancel_actor_timeout(this);
+}
+inline void Actor::migrate(int32 sched_id) {
+  Scheduler::instance()->migrate_actor(this, sched_id);
+}
+inline void Actor::do_migrate(int32 sched_id) {
+  Scheduler::instance()->do_migrate_actor(this, sched_id);
+}
+
+template <class ActorType>
+std::enable_if_t<std::is_base_of<Actor, ActorType>::value> start_migrate(ActorType &obj, int32 sched_id) {
+  if (!obj.empty()) {
+    Scheduler::instance()->start_migrate_actor(&obj, sched_id);
+  }
+}
+template <class ActorType>
+std::enable_if_t<std::is_base_of<Actor, ActorType>::value> finish_migrate(ActorType &obj) {
+  if (!obj.empty()) {
+    Scheduler::instance()->finish_migrate_actor(&obj);
+  }
+}
+inline uint64 Actor::get_link_token() {
+  return Scheduler::instance()->get_link_token(this);
+}
+inline void Actor::set_context(std::shared_ptr<ActorContext> context) {
+  info_->set_context(std::move(context));
+}
+inline void Actor::set_tag(CSlice tag) {
+  info_->get_context()->tag_ = tag.c_str();
+  Scheduler::on_context_updated();
+}
+
+inline void Actor::init(ObjectPool<ActorInfo>::OwnerPtr &&info) {
+  info_ = std::move(info);
+}
+inline ActorInfo *Actor::get_info() {
+  return &*info_;
+}
+inline const ActorInfo *Actor::get_info() const {
+  return &*info_;
+}
+inline ObjectPool<ActorInfo>::OwnerPtr Actor::clear() {
+  return std::move(info_);
+}
+
+inline bool Actor::empty() const {
+  return info_.empty();
+}
+
+inline ActorId<> Actor::actor_id() {
+  return actor_id(this);
+}
+template <class SelfT>
+ActorId<SelfT> Actor::actor_id(SelfT *self) {
+  CHECK(static_cast<Actor *>(self) == this);
+  return ActorId<SelfT>(info_.get_weak());
+}
+
+inline ActorShared<> Actor::actor_shared() {
+  return actor_shared(this);
+}
+template <class SelfT>
+ActorShared<SelfT> Actor::actor_shared(SelfT *self, uint64 id) {
+  CHECK(static_cast<Actor *>(self) == this);
+  return ActorShared<SelfT>(actor_id(self), id);
+}
+
+template <class FuncT, class... ArgsT>
+auto Actor::self_closure(FuncT &&func, ArgsT &&... args) {
+  return self_closure(this, std::forward<FuncT>(func), std::forward<ArgsT>(args)...);
+}
+
+template <class SelfT, class FuncT, class... ArgsT>
+auto Actor::self_closure(SelfT *self, FuncT &&func, ArgsT &&... args) {
+  return EventCreator::closure(actor_id(self), std::forward<FuncT>(func), std::forward<ArgsT>(args)...);
+}
+
+template <class LambdaT>
+auto Actor::self_lambda(LambdaT &&lambda) {
+  return EventCreator::lambda(actor_id(), std::forward<LambdaT>(lambda));
+}
+
+inline Slice Actor::get_name() const {
+  return info_->get_name();
+}
+
+inline void Actor::always_wait_for_mailbox() {
+  info_->always_wait_for_mailbox();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl/ActorId-decl.h b/libs/tdlib/td/tdactor/td/actor/impl/ActorId-decl.h
new file mode 100644
index 0000000000..5e82ed6a05
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl/ActorId-decl.h
@@ -0,0 +1,169 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/ObjectPool.h"
+#include "td/utils/Slice.h"
+
+#include <type_traits>
+
+namespace td {
+class ActorInfo;
+class Actor;
+template <class ActorType = Actor>
+class ActorId {
+ public:
+  using ActorT = ActorType;
+  explicit ActorId(ObjectPool<ActorInfo>::WeakPtr ptr) : ptr_(ptr) {
+  }
+  ActorId() = default;
+  ActorId(const ActorId &) = default;
+  ActorId &operator=(const ActorId &) = default;
+  ActorId(ActorId &&other) : ptr_(other.ptr_) {
+    other.ptr_.clear();
+  }
+  ActorId &operator=(ActorId &&other) {
+    if (&other == this) {
+      return *this;
+    }
+    ptr_ = other.ptr_;
+    other.clear();
+    return *this;
+  }
+  ~ActorId() = default;
+
+  bool empty() const {
+    return ptr_.empty();
+  }
+  void clear() {
+    ptr_.clear();
+  }
+
+  bool is_alive() const {
+    return ptr_.is_alive_unsafe();
+  }
+
+  ActorInfo *get_actor_info() const;
+  ActorType *get_actor_unsafe() const;
+
+  // returns pointer to actor if it is on current thread. nullptr otherwise
+  ActorType *try_get_actor() const;
+
+  Slice get_name() const;
+
+  template <class ToActorType, class = std::enable_if_t<std::is_base_of<ToActorType, ActorType>::value>>
+  explicit operator ActorId<ToActorType>() const {
+    return ActorId<ToActorType>(ptr_);
+  }
+
+  template <class AsActorType>
+  ActorId<AsActorType> as() const {
+    return ActorId<AsActorType>(ptr_);
+  }
+
+ private:
+  ObjectPool<ActorInfo>::WeakPtr ptr_;
+};
+
+// threat ActorId as pointer and ActorOwn as
+// unique_ptr<ActorId>
+template <class ActorType = Actor>
+class ActorOwn {
+ public:
+  using ActorT = ActorType;
+  ActorOwn() = default;
+  explicit ActorOwn(ActorId<ActorType>);
+  template <class OtherActorType>
+  explicit ActorOwn(ActorId<OtherActorType> id);
+  template <class OtherActorType>
+  explicit ActorOwn(ActorOwn<OtherActorType> &&);
+  template <class OtherActorType>
+  ActorOwn &operator=(ActorOwn<OtherActorType> &&);
+  ActorOwn(ActorOwn &&);
+  ActorOwn &operator=(ActorOwn &&);
+  ActorOwn(const ActorOwn &) = delete;
+  ActorOwn &operator=(const ActorOwn &) = delete;
+  ~ActorOwn();
+
+  bool empty() const;
+  bool is_alive() const {
+    return id_.is_alive();
+  }
+  ActorId<ActorType> get() const;
+  ActorId<ActorType> release();
+  void reset(ActorId<ActorType> other = ActorId<ActorType>());
+  void hangup() const;
+  const ActorId<ActorType> *operator->() const;
+
+  using ActorIdConstRef = const ActorId<ActorType> &;
+  // operator ActorIdConstRef();
+
+ private:
+  ActorId<ActorType> id_;
+};
+
+template <class ActorType = Actor>
+class ActorShared {
+ public:
+  using ActorT = ActorType;
+  ActorShared() = default;
+  template <class OtherActorType>
+  ActorShared(ActorId<OtherActorType>, uint64 token);
+  template <class OtherActorType>
+  ActorShared(ActorShared<OtherActorType> &&);
+  template <class OtherActorType>
+  ActorShared(ActorOwn<OtherActorType> &&);
+  template <class OtherActorType>
+  ActorShared &operator=(ActorShared<OtherActorType> &&);
+  ActorShared(ActorShared &&);
+  ActorShared &operator=(ActorShared &&);
+  ActorShared(const ActorShared &) = delete;
+  ActorShared &operator=(const ActorShared &) = delete;
+  ~ActorShared();
+
+  uint64 token() const;
+  bool empty() const;
+  bool is_alive() const {
+    return id_.is_alive();
+  }
+  ActorId<ActorType> get() const;
+  ActorId<ActorType> release();
+  void reset(ActorId<ActorType> other = ActorId<ActorType>());
+  template <class OtherActorType>
+  void reset(ActorId<OtherActorType> other);
+  const ActorId<ActorType> *operator->() const;
+
+ private:
+  ActorId<ActorType> id_;
+  uint64 token_;
+};
+
+class ActorRef {
+ public:
+  ActorRef() = default;
+  template <class T>
+  ActorRef(const ActorId<T> &actor_id);
+  template <class T>
+  ActorRef(const ActorShared<T> &actor_id);
+  template <class T>
+  ActorRef(ActorShared<T> &&actor_id);
+  template <class T>
+  ActorRef(const ActorOwn<T> &actor_id);
+  template <class T>
+  ActorRef(ActorOwn<T> &&actor_id);
+  ActorId<> get() const {
+    return actor_id_;
+  }
+  uint64 token() const {
+    return token_;
+  }
+
+ private:
+  ActorId<> actor_id_;
+  uint64 token_ = 0;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl/ActorId.h b/libs/tdlib/td/tdactor/td/actor/impl/ActorId.h
new file mode 100644
index 0000000000..34d7970633
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl/ActorId.h
@@ -0,0 +1,200 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/impl/ActorId-decl.h"
+#include "td/actor/impl/ActorInfo-decl.h"
+#include "td/actor/impl/Scheduler-decl.h"
+
+#include "td/utils/Slice.h"
+
+namespace td {
+/*** ActorId ***/
+
+// If actor is on our scheduler(thread) result will be valid
+// If actor is on another scheduler we will see it in migrate_dest_flags
+template <class ActorType>
+ActorInfo *ActorId<ActorType>::get_actor_info() const {
+  if (ptr_.is_alive()) {
+    return &*ptr_;
+  }
+  return nullptr;
+}
+
+template <class ActorType>
+ActorType *ActorId<ActorType>::get_actor_unsafe() const {
+  return static_cast<ActorType *>(ptr_->get_actor_unsafe());
+}
+
+template <class ActorType>
+ActorType *ActorId<ActorType>::try_get_actor() const {
+  auto info = get_actor_info();
+  if (info && !info->is_migrating() && Scheduler::instance()->sched_id() == info->migrate_dest()) {
+    return static_cast<ActorType *>(info->get_actor_unsafe());
+  }
+  return nullptr;
+}
+
+template <class ActorType>
+Slice ActorId<ActorType>::get_name() const {
+  return ptr_->get_name();
+}
+
+// ActorOwn
+template <class ActorType>
+ActorOwn<ActorType>::ActorOwn(ActorId<ActorType> id) : id_(std::move(id)) {
+}
+template <class ActorType>
+template <class OtherActorType>
+ActorOwn<ActorType>::ActorOwn(ActorId<OtherActorType> id) : id_(std::move(id)) {
+}
+template <class ActorType>
+template <class OtherActorType>
+ActorOwn<ActorType>::ActorOwn(ActorOwn<OtherActorType> &&other) : id_(other.release()) {
+}
+template <class ActorType>
+template <class OtherActorType>
+ActorOwn<ActorType> &ActorOwn<ActorType>::operator=(ActorOwn<OtherActorType> &&other) {
+  reset(static_cast<ActorId<ActorType>>(other.release()));
+  return *this;
+}
+
+template <class ActorType>
+ActorOwn<ActorType>::ActorOwn(ActorOwn &&other) : id_(other.release()) {
+}
+template <class ActorType>
+ActorOwn<ActorType> &ActorOwn<ActorType>::operator=(ActorOwn &&other) {
+  reset(other.release());
+  return *this;
+}
+
+template <class ActorType>
+ActorOwn<ActorType>::~ActorOwn() {
+  reset();
+}
+
+template <class ActorType>
+bool ActorOwn<ActorType>::empty() const {
+  return id_.empty();
+}
+template <class ActorType>
+ActorId<ActorType> ActorOwn<ActorType>::get() const {
+  return id_;
+}
+
+template <class ActorType>
+ActorId<ActorType> ActorOwn<ActorType>::release() {
+  return std::move(id_);
+}
+template <class ActorType>
+void ActorOwn<ActorType>::reset(ActorId<ActorType> other) {
+  static_assert(sizeof(ActorType) > 0, "Can't use ActorOwn with incomplete type");
+  hangup();
+  id_ = std::move(other);
+}
+
+template <class ActorType>
+void ActorOwn<ActorType>::hangup() const {
+  if (!id_.empty()) {
+    send_event(id_, Event::hangup());
+  }
+}
+template <class ActorType>
+const ActorId<ActorType> *ActorOwn<ActorType>::operator->() const {
+  return &id_;
+}
+
+// ActorShared
+template <class ActorType>
+template <class OtherActorType>
+ActorShared<ActorType>::ActorShared(ActorId<OtherActorType> id, uint64 token) : id_(std::move(id)), token_(token) {
+}
+template <class ActorType>
+template <class OtherActorType>
+ActorShared<ActorType>::ActorShared(ActorShared<OtherActorType> &&other) : id_(other.release()), token_(other.token()) {
+}
+template <class ActorType>
+template <class OtherActorType>
+ActorShared<ActorType>::ActorShared(ActorOwn<OtherActorType> &&other) : id_(other.release()), token_(0) {
+}
+template <class ActorType>
+template <class OtherActorType>
+ActorShared<ActorType> &ActorShared<ActorType>::operator=(ActorShared<OtherActorType> &&other) {
+  reset(other.release());
+  token_ = other.token();
+  return *this;
+}
+
+template <class ActorType>
+ActorShared<ActorType>::ActorShared(ActorShared &&other) : id_(other.release()), token_(other.token_) {
+}
+template <class ActorType>
+ActorShared<ActorType> &ActorShared<ActorType>::operator=(ActorShared &&other) {
+  reset(other.release());
+  token_ = other.token_;
+  return *this;
+}
+
+template <class ActorType>
+ActorShared<ActorType>::~ActorShared() {
+  reset();
+}
+
+template <class ActorType>
+uint64 ActorShared<ActorType>::token() const {
+  return token_;
+}
+template <class ActorType>
+bool ActorShared<ActorType>::empty() const {
+  return id_.empty();
+}
+template <class ActorType>
+ActorId<ActorType> ActorShared<ActorType>::get() const {
+  return id_;
+}
+
+template <class ActorType>
+ActorId<ActorType> ActorShared<ActorType>::release() {
+  return std::move(id_);
+}
+template <class ActorType>
+void ActorShared<ActorType>::reset(ActorId<ActorType> other) {
+  reset<ActorType>(std::move(other));
+}
+
+template <class ActorType>
+template <class OtherActorType>
+void ActorShared<ActorType>::reset(ActorId<OtherActorType> other) {
+  static_assert(sizeof(ActorType) > 0, "Can't use ActorShared with incomplete type");
+  if (!id_.empty()) {
+    send_event(*this, Event::hangup());
+  }
+  id_ = static_cast<ActorId<ActorType>>(other);
+}
+template <class ActorType>
+const ActorId<ActorType> *ActorShared<ActorType>::operator->() const {
+  return &id_;
+}
+
+/*** ActorRef ***/
+template <class T>
+ActorRef::ActorRef(const ActorId<T> &actor_id) : actor_id_(actor_id) {
+}
+template <class T>
+ActorRef::ActorRef(const ActorShared<T> &actor_id) : actor_id_(actor_id.get()), token_(actor_id.token()) {
+}
+template <class T>
+ActorRef::ActorRef(ActorShared<T> &&actor_id) : actor_id_(actor_id.release()), token_(actor_id.token()) {
+}
+template <class T>
+ActorRef::ActorRef(const ActorOwn<T> &actor_id) : actor_id_(actor_id.get()) {
+}
+template <class T>
+ActorRef::ActorRef(ActorOwn<T> &&actor_id) : actor_id_(actor_id.release()) {
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl/ActorInfo-decl.h b/libs/tdlib/td/tdactor/td/actor/impl/ActorInfo-decl.h
new file mode 100644
index 0000000000..de9fba794e
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl/ActorInfo-decl.h
@@ -0,0 +1,119 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/impl/ActorId-decl.h"
+#include "td/actor/impl/Event.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Heap.h"
+#include "td/utils/List.h"
+#include "td/utils/ObjectPool.h"
+#include "td/utils/Slice.h"
+#include "td/utils/StringBuilder.h"
+
+#include <atomic>
+#include <memory>
+#include <utility>
+
+namespace td {
+
+class Actor;
+
+class ActorContext {
+ public:
+  ActorContext() = default;
+  ActorContext(const ActorContext &) = delete;
+  ActorContext &operator=(const ActorContext &) = delete;
+  ActorContext(ActorContext &&) = delete;
+  ActorContext &operator=(ActorContext &&) = delete;
+  virtual ~ActorContext() = default;
+  const char *tag_ = nullptr;
+  std::weak_ptr<ActorContext> this_ptr_;
+};
+
+class ActorInfo
+    : private ListNode
+    , HeapNode {
+ public:
+  enum class Deleter : uint8 { Destroy, None };
+
+  ActorInfo() = default;
+  ~ActorInfo() = default;
+
+  ActorInfo(ActorInfo &&) = delete;
+  ActorInfo &operator=(ActorInfo &&) = delete;
+
+  ActorInfo(const ActorInfo &) = delete;
+  ActorInfo &operator=(const ActorInfo &) = delete;
+
+  void init(int32 sched_id, Slice name, ObjectPool<ActorInfo>::OwnerPtr &&this_ptr, Actor *actor_ptr, Deleter deleter,
+            bool is_lite);
+  void on_actor_moved(Actor *actor_new_ptr);
+
+  template <class ActorT>
+  ActorOwn<ActorT> transfer_ownership_to_scheduler(std::unique_ptr<ActorT> actor);
+  void clear();
+  void destroy_actor();
+
+  bool empty() const;
+  void start_migrate(int32 to_sched_id);
+  bool is_migrating() const;
+  int32 migrate_dest() const;
+  std::pair<int32, bool> migrate_dest_flag_atomic() const;
+
+  void finish_migrate();
+
+  ActorId<> actor_id();
+  template <class SelfT>
+  ActorId<SelfT> actor_id(SelfT *self);
+  Actor *get_actor_unsafe();
+  const Actor *get_actor_unsafe() const;
+
+  void set_context(std::shared_ptr<ActorContext> context);
+  ActorContext *get_context();
+  const ActorContext *get_context() const;
+  CSlice get_name() const;
+
+  HeapNode *get_heap_node();
+  const HeapNode *get_heap_node() const;
+  static ActorInfo *from_heap_node(HeapNode *node);
+
+  ListNode *get_list_node();
+  const ListNode *get_list_node() const;
+  static ActorInfo *from_list_node(ListNode *node);
+
+  void start_run();
+  bool is_running() const;
+  void finish_run();
+
+  vector<Event> mailbox_;
+
+  bool is_lite() const;
+
+  void set_wait_generation(uint32 wait_generation);
+  bool must_wait(uint32 wait_generation) const;
+  void always_wait_for_mailbox();
+
+ private:
+  Deleter deleter_;
+  bool is_lite_;
+  bool is_running_;
+  bool always_wait_for_mailbox_{false};
+  uint32 wait_generation_{0};
+
+  std::atomic<int32> sched_id_{0};
+  Actor *actor_ = nullptr;
+
+#ifdef TD_DEBUG
+  string name_;
+#endif
+  std::shared_ptr<ActorContext> context_;
+};
+
+StringBuilder &operator<<(StringBuilder &sb, const ActorInfo &info);
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl/ActorInfo.h b/libs/tdlib/td/tdactor/td/actor/impl/ActorInfo.h
new file mode 100644
index 0000000000..df0b0dfd81
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl/ActorInfo.h
@@ -0,0 +1,201 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/impl/Actor-decl.h"
+#include "td/actor/impl/ActorInfo-decl.h"
+#include "td/actor/impl/Scheduler-decl.h"
+
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/Heap.h"
+#include "td/utils/List.h"
+#include "td/utils/logging.h"
+#include "td/utils/ObjectPool.h"
+#include "td/utils/Slice.h"
+#include "td/utils/StringBuilder.h"
+
+#include <atomic>
+#include <memory>
+#include <utility>
+
+namespace td {
+/*** ActorInfo ***/
+inline StringBuilder &operator<<(StringBuilder &sb, const ActorInfo &info) {
+  sb << info.get_name() << ":" << const_cast<void *>(static_cast<const void *>(&info)) << ":"
+     << const_cast<void *>(static_cast<const void *>(info.get_context()));
+  return sb;
+}
+inline void ActorInfo::init(int32 sched_id, Slice name, ObjectPool<ActorInfo>::OwnerPtr &&this_ptr, Actor *actor_ptr,
+                            Deleter deleter, bool is_lite) {
+  CHECK(!is_running());
+  CHECK(!is_migrating());
+  sched_id_.store(sched_id, std::memory_order_relaxed);
+  actor_ = actor_ptr;
+
+  if (!is_lite) {
+    context_ = Scheduler::context()->this_ptr_.lock();
+#ifdef TD_DEBUG
+    name_ = name.str();
+#endif
+  }
+
+  actor_->init(std::move(this_ptr));
+  deleter_ = deleter;
+  is_lite_ = is_lite;
+  is_running_ = false;
+  wait_generation_ = 0;
+}
+inline bool ActorInfo::is_lite() const {
+  return is_lite_;
+}
+inline void ActorInfo::set_wait_generation(uint32 wait_generation) {
+  wait_generation_ = wait_generation;
+}
+inline bool ActorInfo::must_wait(uint32 wait_generation) const {
+  return wait_generation_ == wait_generation || (always_wait_for_mailbox_ && !mailbox_.empty());
+}
+inline void ActorInfo::always_wait_for_mailbox() {
+  always_wait_for_mailbox_ = true;
+}
+inline void ActorInfo::on_actor_moved(Actor *actor_new_ptr) {
+  actor_ = actor_new_ptr;
+}
+
+inline void ActorInfo::clear() {
+  //  LOG_IF(WARNING, !mailbox_.empty()) << "Destroy actor with non-empty mailbox: " << get_name()
+  //                                     << format::as_array(mailbox_);
+  mailbox_.clear();
+  CHECK(!is_running());
+  CHECK(!is_migrating());
+  // NB: must be in non migrating state
+  // store invalid scheduler id.
+  sched_id_.store((1 << 30) - 1, std::memory_order_relaxed);
+  destroy_actor();
+  // Destroy context only after destructor.
+  context_.reset();
+}
+
+inline void ActorInfo::destroy_actor() {
+  if (!actor_) {
+    return;
+  }
+  switch (deleter_) {
+    case Deleter::Destroy:
+      std::default_delete<Actor>()(actor_);
+      break;
+    case Deleter::None:
+      break;
+  }
+  actor_ = nullptr;
+}
+
+template <class ActorT>
+ActorOwn<ActorT> ActorInfo::transfer_ownership_to_scheduler(std::unique_ptr<ActorT> actor) {
+  CHECK(!empty());
+  CHECK(deleter_ == Deleter::None);
+  ActorT *actor_ptr = actor.release();
+  CHECK(actor_ == static_cast<Actor *>(actor_ptr));
+  actor_ = static_cast<Actor *>(actor_ptr);
+  deleter_ = Deleter::Destroy;
+  return ActorOwn<ActorT>(actor_id(actor_ptr));
+}
+
+inline bool ActorInfo::empty() const {
+  return actor_ == nullptr;
+}
+
+inline void ActorInfo::start_migrate(int32 to_sched_id) {
+  sched_id_.store(to_sched_id | (1 << 30), std::memory_order_relaxed);
+}
+inline std::pair<int32, bool> ActorInfo::migrate_dest_flag_atomic() const {
+  int32 sched_id = sched_id_.load(std::memory_order_relaxed);
+  return std::make_pair(sched_id & ~(1 << 30), (sched_id & (1 << 30)) != 0);
+}
+inline void ActorInfo::finish_migrate() {
+  sched_id_.store(migrate_dest(), std::memory_order_relaxed);
+}
+inline bool ActorInfo::is_migrating() const {
+  return migrate_dest_flag_atomic().second;
+}
+inline int32 ActorInfo::migrate_dest() const {
+  return migrate_dest_flag_atomic().first;
+}
+
+inline ActorId<> ActorInfo::actor_id() {
+  return actor_id(actor_);
+}
+
+template <class SelfT>
+ActorId<SelfT> ActorInfo::actor_id(SelfT *self) {
+  return actor_->actor_id(self);
+}
+
+inline Actor *ActorInfo::get_actor_unsafe() {
+  return actor_;
+}
+inline const Actor *ActorInfo::get_actor_unsafe() const {
+  return actor_;
+}
+
+inline void ActorInfo::set_context(std::shared_ptr<ActorContext> context) {
+  CHECK(is_running());
+  context->this_ptr_ = context;
+  context->tag_ = Scheduler::context()->tag_;
+  context_ = std::move(context);
+  Scheduler::context() = context_.get();
+  Scheduler::on_context_updated();
+}
+inline const ActorContext *ActorInfo::get_context() const {
+  return context_.get();
+}
+
+inline ActorContext *ActorInfo::get_context() {
+  return context_.get();
+}
+
+inline CSlice ActorInfo::get_name() const {
+#ifdef TD_DEBUG
+  return name_;
+#else
+  return "";
+#endif
+}
+
+inline void ActorInfo::start_run() {
+  VLOG(actor) << "start_run: " << *this;
+  CHECK(!is_running_) << "Recursive call of actor " << tag("name", get_name());
+  is_running_ = true;
+}
+inline void ActorInfo::finish_run() {
+  is_running_ = false;
+  VLOG(actor) << "stop_run: " << *this;
+}
+
+inline bool ActorInfo::is_running() const {
+  return is_running_;
+}
+
+inline HeapNode *ActorInfo::get_heap_node() {
+  return this;
+}
+inline const HeapNode *ActorInfo::get_heap_node() const {
+  return this;
+}
+inline ActorInfo *ActorInfo::from_heap_node(HeapNode *node) {
+  return static_cast<ActorInfo *>(node);
+}
+inline ListNode *ActorInfo::get_list_node() {
+  return this;
+}
+inline const ListNode *ActorInfo::get_list_node() const {
+  return this;
+}
+inline ActorInfo *ActorInfo::from_list_node(ListNode *node) {
+  return static_cast<ActorInfo *>(node);
+}
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl/ConcurrentScheduler.cpp b/libs/tdlib/td/tdactor/td/actor/impl/ConcurrentScheduler.cpp
new file mode 100644
index 0000000000..47593db90b
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl/ConcurrentScheduler.cpp
@@ -0,0 +1,102 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/actor/impl/ConcurrentScheduler.h"
+
+#include "td/actor/impl/Actor.h"
+#include "td/actor/impl/ActorId.h"
+#include "td/actor/impl/ActorInfo.h"
+#include "td/actor/impl/Scheduler.h"
+
+#include "td/utils/MpscPollableQueue.h"
+#include "td/utils/port/thread_local.h"
+
+#include <memory>
+
+namespace td {
+
+void ConcurrentScheduler::init(int32 threads_n) {
+#if TD_THREAD_UNSUPPORTED || TD_EVENTFD_UNSUPPORTED
+  threads_n = 0;
+#endif
+  threads_n++;
+  std::vector<std::shared_ptr<MpscPollableQueue<EventFull>>> outbound(threads_n);
+  for (int32 i = 0; i < threads_n; i++) {
+#if TD_THREAD_UNSUPPORTED || TD_EVENTFD_UNSUPPORTED
+#else
+    auto queue = std::make_shared<MpscPollableQueue<EventFull>>();
+    queue->init();
+    outbound[i] = queue;
+#endif
+  }
+
+  schedulers_.resize(threads_n);
+  for (int32 i = 0; i < threads_n; i++) {
+    auto &sched = schedulers_[i];
+    sched = make_unique<Scheduler>();
+    sched->init(i, outbound, static_cast<Scheduler::Callback *>(this));
+  }
+
+  state_ = State::Start;
+}
+
+void ConcurrentScheduler::test_one_thread_run() {
+  do {
+    for (auto &sched : schedulers_) {
+      sched->run(0);
+    }
+  } while (!is_finished_.load(std::memory_order_relaxed));
+}
+
+void ConcurrentScheduler::start() {
+  CHECK(state_ == State::Start);
+  is_finished_.store(false, std::memory_order_relaxed);
+  set_thread_id(0);
+#if !TD_THREAD_UNSUPPORTED && !TD_EVENTFD_UNSUPPORTED
+  for (size_t i = 1; i < schedulers_.size(); i++) {
+    auto &sched = schedulers_[i];
+    threads_.push_back(td::thread([&, tid = i]() {
+      set_thread_id(static_cast<int32>(tid));
+      while (!is_finished()) {
+        sched->run(10);
+      }
+    }));
+  }
+#endif
+  state_ = State::Run;
+}
+
+bool ConcurrentScheduler::run_main(double timeout) {
+  CHECK(state_ == State::Run);
+  // run main scheduler in same thread
+  auto &main_sched = schedulers_[0];
+  if (!is_finished()) {
+    main_sched->run(timeout);
+  }
+  return !is_finished();
+}
+
+void ConcurrentScheduler::finish() {
+  CHECK(state_ == State::Run);
+  if (!is_finished()) {
+    on_finish();
+  }
+#if !TD_THREAD_UNSUPPORTED && !TD_EVENTFD_UNSUPPORTED
+  for (auto &thread : threads_) {
+    thread.join();
+  }
+  threads_.clear();
+#endif
+  schedulers_.clear();
+  for (auto &f : at_finish_) {
+    f();
+  }
+  at_finish_.clear();
+
+  state_ = State::Start;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl/ConcurrentScheduler.h b/libs/tdlib/td/tdactor/td/actor/impl/ConcurrentScheduler.h
new file mode 100644
index 0000000000..1e9793eab4
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl/ConcurrentScheduler.h
@@ -0,0 +1,93 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/impl/Scheduler-decl.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/thread.h"
+#include "td/utils/Slice.h"
+
+#include <atomic>
+#include <functional>
+#include <mutex>
+#include <utility>
+
+namespace td {
+
+class ConcurrentScheduler : private Scheduler::Callback {
+ public:
+  void init(int32 threads_n);
+
+  void finish_async() {
+    schedulers_[0]->finish();
+  }
+  void wakeup() {
+    schedulers_[0]->wakeup();
+  }
+  SchedulerGuard get_current_guard() {
+    return schedulers_[0]->get_guard();
+  }
+
+  void test_one_thread_run();
+
+  bool is_finished() {
+    return is_finished_.load(std::memory_order_relaxed);
+  }
+
+  void start();
+
+  bool run_main(double timeout);
+
+  void finish();
+
+  template <class ActorT, class... Args>
+  ActorOwn<ActorT> create_actor_unsafe(int32 sched_id, Slice name, Args &&... args) {
+#if TD_THREAD_UNSUPPORTED || TD_EVENTFD_UNSUPPORTED
+    sched_id = 0;
+#endif
+    CHECK(0 <= sched_id && sched_id < static_cast<int32>(schedulers_.size()));
+    auto guard = schedulers_[sched_id]->get_guard();
+    return schedulers_[sched_id]->create_actor<ActorT>(name, std::forward<Args>(args)...);
+  }
+
+  template <class ActorT>
+  ActorOwn<ActorT> register_actor_unsafe(int32 sched_id, Slice name, ActorT *actor) {
+#if TD_THREAD_UNSUPPORTED || TD_EVENTFD_UNSUPPORTED
+    sched_id = 0;
+#endif
+    CHECK(0 <= sched_id && sched_id < static_cast<int32>(schedulers_.size()));
+    auto guard = schedulers_[sched_id]->get_guard();
+    return schedulers_[sched_id]->register_actor<ActorT>(name, actor);
+  }
+
+ private:
+  enum class State { Start, Run };
+  State state_;
+  std::vector<unique_ptr<Scheduler>> schedulers_;
+  std::atomic<bool> is_finished_;
+  std::mutex at_finish_mutex_;
+  std::vector<std::function<void()>> at_finish_;
+#if !TD_THREAD_UNSUPPORTED && !TD_EVENTFD_UNSUPPORTED
+  std::vector<thread> threads_;
+#endif
+
+  void on_finish() override {
+    is_finished_.store(true, std::memory_order_relaxed);
+    for (auto &it : schedulers_) {
+      it->wakeup();
+    }
+  }
+
+  void register_at_finish(std::function<void()> f) override {
+    std::lock_guard<std::mutex> lock(at_finish_mutex_);
+    at_finish_.push_back(std::move(f));
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl/Event.h b/libs/tdlib/td/tdactor/td/actor/impl/Event.h
new file mode 100644
index 0000000000..fac66dd120
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl/Event.h
@@ -0,0 +1,247 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/Closure.h"
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/StringBuilder.h"
+
+#include <type_traits>
+#include <utility>
+
+namespace td {
+
+class Actor;
+
+// Events
+//
+// Small structure (up to 16 bytes) used to send events between actors.
+//
+// There are some predefined types of events:
+// NoType -- unitialized event
+// Start -- start actor
+// Stop -- stop actor
+// Yield -- wake up actor
+// Timeout -- some timeout has expired
+// Hangup -- hang up called
+// Raw -- just pass 8 bytes (union Raw is used for convenience)
+// Custom -- Send CustomEvent
+
+template <class T>
+std::enable_if_t<!std::is_base_of<Actor, T>::value> start_migrate(T &obj, int32 sched_id) {
+}
+template <class T>
+std::enable_if_t<!std::is_base_of<Actor, T>::value> finish_migrate(T &obj) {
+}
+
+class CustomEvent {
+ public:
+  CustomEvent() = default;
+  CustomEvent(const CustomEvent &) = delete;
+  CustomEvent &operator=(const CustomEvent &) = delete;
+  CustomEvent(CustomEvent &&) = delete;
+  CustomEvent &operator=(CustomEvent &&) = delete;
+  virtual ~CustomEvent() = default;
+
+  virtual void run(Actor *actor) = 0;
+  virtual CustomEvent *clone() const = 0;
+  virtual void start_migrate(int32 sched_id) {
+  }
+  virtual void finish_migrate() {
+  }
+};
+
+template <class ClosureT>
+class ClosureEvent : public CustomEvent {
+ public:
+  void run(Actor *actor) override {
+    closure_.run(static_cast<typename ClosureT::ActorType *>(actor));
+  }
+  CustomEvent *clone() const override {
+    return new ClosureEvent<ClosureT>(closure_.clone());
+  }
+  template <class... ArgsT>
+  explicit ClosureEvent(ArgsT &&... args) : closure_(std::forward<ArgsT>(args)...) {
+  }
+
+  void start_migrate(int32 sched_id) override {
+    closure_.for_each([sched_id](auto &obj) {
+      using ::td::start_migrate;
+      start_migrate(obj, sched_id);
+    });
+  }
+
+  void finish_migrate() override {
+    closure_.for_each([](auto &obj) {
+      using ::td::finish_migrate;
+      finish_migrate(obj);
+    });
+  }
+
+ private:
+  ClosureT closure_;
+};
+
+template <class LambdaT>
+class LambdaEvent : public CustomEvent {
+ public:
+  void run(Actor *actor) override {
+    f_();
+  }
+  CustomEvent *clone() const override {
+    LOG(FATAL) << "Not supported";
+    return nullptr;
+  }
+  template <class FromLambdaT>
+  explicit LambdaEvent(FromLambdaT &&lambda) : f_(std::forward<FromLambdaT>(lambda)) {
+  }
+
+ private:
+  LambdaT f_;
+};
+
+class Event {
+ public:
+  enum class Type { NoType, Start, Stop, Yield, Timeout, Hangup, Raw, Custom };
+  Type type;
+  uint64 link_token = 0;
+  union Raw {
+    void *ptr;
+    CustomEvent *custom_event;
+    uint32 u32;
+    uint64 u64;
+  } data{};
+
+  // factory functions
+  static Event start() {
+    return Event(Type::Start);
+  }
+  static Event stop() {
+    return Event(Type::Stop);
+  }
+  static Event yield() {
+    return Event(Type::Yield);
+  }
+  static Event timeout() {
+    return Event(Type::Timeout);
+  }
+  static Event hangup() {
+    return Event(Type::Hangup);
+  }
+  static Event raw(void *ptr) {
+    return Event(Type::Raw, ptr);
+  }
+  static Event raw(uint32 u32) {
+    return Event(Type::Raw, u32);
+  }
+  static Event raw(uint64 u64) {
+    return Event(Type::Raw, u64);
+  }
+  static Event custom(CustomEvent *custom_event) {
+    return Event(Type::Custom, custom_event);
+  }
+
+  template <class FromImmediateClosureT>
+  static Event immediate_closure(FromImmediateClosureT &&closure) {
+    return custom(
+        new ClosureEvent<typename FromImmediateClosureT::Delayed>(std::forward<FromImmediateClosureT>(closure)));
+  }
+  template <class... ArgsT>
+  static Event delayed_closure(ArgsT &&... args) {
+    using DelayedClosureT = decltype(create_delayed_closure(std::forward<ArgsT>(args)...));
+    return custom(new ClosureEvent<DelayedClosureT>(std::forward<ArgsT>(args)...));
+  }
+
+  template <class FromLambdaT>
+  static Event lambda(FromLambdaT &&lambda) {
+    return custom(new LambdaEvent<std::decay_t<FromLambdaT>>(std::forward<FromLambdaT>(lambda)));
+  }
+
+  Event() : Event(Type::NoType) {
+  }
+  Event(const Event &other) = delete;
+  Event &operator=(const Event &) = delete;
+  Event(Event &&other) : type(other.type), link_token(other.link_token), data(other.data) {
+    other.type = Type::NoType;
+  }
+  Event &operator=(Event &&other) {
+    destroy();
+    type = other.type;
+    link_token = other.link_token;
+    data = other.data;
+    other.type = Type::NoType;
+    return *this;
+  }
+  ~Event() {
+    destroy();
+  }
+
+  Event clone() const {
+    Event res;
+    res.type = type;
+    if (type == Type::Custom) {
+      res.data.custom_event = data.custom_event->clone();
+    } else {
+      res.data = data;
+    }
+    return res;
+  }
+
+  bool empty() const {
+    return type == Type::NoType;
+  }
+
+  void clear() {
+    destroy();
+    type = Type::NoType;
+  }
+
+  Event &set_link_token(uint64 new_link_token) {
+    link_token = new_link_token;
+    return *this;
+  }
+
+  friend void start_migrate(Event &obj, int32 sched_id) {
+    if (obj.type == Type::Custom) {
+      obj.data.custom_event->start_migrate(sched_id);
+    }
+  }
+  friend void finish_migrate(Event &obj) {
+    if (obj.type == Type::Custom) {
+      obj.data.custom_event->finish_migrate();
+    }
+  }
+
+ private:
+  explicit Event(Type type) : type(type) {
+  }
+
+  Event(Type type, void *ptr) : Event(type) {
+    data.ptr = ptr;
+  }
+  Event(Type type, CustomEvent *custom_event) : Event(type) {
+    data.custom_event = custom_event;
+  }
+  Event(Type type, uint32 u32) : Event(type) {
+    data.u32 = u32;
+  }
+  Event(Type type, uint64 u64) : Event(type) {
+    data.u64 = u64;
+  }
+
+  void destroy() {
+    if (type == Type::Custom) {
+      delete data.custom_event;
+    }
+  }
+};
+inline StringBuilder &operator<<(StringBuilder &sb, const Event &e) {
+  return sb << tag("Event", static_cast<int32>(e.type));
+}
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl/EventFull-decl.h b/libs/tdlib/td/tdactor/td/actor/impl/EventFull-decl.h
new file mode 100644
index 0000000000..ef2f1c2dcb
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl/EventFull-decl.h
@@ -0,0 +1,87 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/impl/ActorId-decl.h"
+#include "td/actor/impl/Event.h"
+
+#include "td/utils/type_traits.h"
+
+#include <type_traits>
+#include <utility>
+
+namespace td {
+
+class EventFull {
+ public:
+  EventFull() = default;
+
+  bool empty() const {
+    return data_.empty();
+  }
+
+  void clear() {
+    data_.clear();
+  }
+
+  ActorId<> actor_id() const {
+    return actor_id_;
+  }
+  Event &data() {
+    return data_;
+  }
+
+  void try_emit_later();
+  void try_emit();
+
+ private:
+  friend class EventCreator;
+
+  EventFull(ActorRef actor_ref, Event &&data) : actor_id_(actor_ref.get()), data_(std::move(data)) {
+    data_.link_token = actor_ref.token();
+  }
+  template <class T>
+  EventFull(ActorId<T> actor_id, Event &&data) : actor_id_(actor_id), data_(std::move(data)) {
+  }
+
+  ActorId<> actor_id_;
+
+  Event data_;
+};
+
+class EventCreator {
+ public:
+  template <class ActorIdT, class FunctionT, class... ArgsT>
+  static EventFull closure(ActorIdT &&actor_id, FunctionT function, ArgsT &&... args) {
+    using ActorT = typename std::decay_t<ActorIdT>::ActorT;
+    using FunctionClassT = member_function_class_t<FunctionT>;
+    static_assert(std::is_base_of<FunctionClassT, ActorT>::value, "unsafe send_closure");
+
+    return EventFull(std::forward<ActorIdT>(actor_id), Event::delayed_closure(function, std::forward<ArgsT>(args)...));
+  }
+
+  template <class LambdaT>
+  static EventFull lambda(ActorRef actor_ref, LambdaT &&lambda) {
+    return EventFull(actor_ref, Event::lambda(std::forward<LambdaT>(lambda)));
+  }
+
+  static EventFull yield(ActorRef actor_ref) {
+    return EventFull(actor_ref, Event::yield());
+  }
+  static EventFull raw(ActorRef actor_ref, uint64 data) {
+    return EventFull(actor_ref, Event::raw(data));
+  }
+  static EventFull raw(ActorRef actor_ref, void *ptr) {
+    return EventFull(actor_ref, Event::raw(ptr));
+  }
+
+  static EventFull event_unsafe(ActorId<> actor_id, Event &&event) {
+    return EventFull(actor_id, std::move(event));
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl/EventFull.h b/libs/tdlib/td/tdactor/td/actor/impl/EventFull.h
new file mode 100644
index 0000000000..1e997ee4b3
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl/EventFull.h
@@ -0,0 +1,38 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/impl/EventFull-decl.h"
+#include "td/actor/impl/Scheduler-decl.h"
+
+#include "td/utils/logging.h"
+
+#include <utility>
+
+namespace td {
+
+inline void EventFull::try_emit_later() {
+  if (empty()) {
+    return;
+  }
+  auto link_token = data_.link_token;
+  send_event_later(ActorShared<>(actor_id_, link_token), std::move(data_));
+  data_.clear();
+  CHECK(empty());
+}
+
+inline void EventFull::try_emit() {
+  if (empty()) {
+    return;
+  }
+  auto link_token = data_.link_token;
+  send_event(ActorShared<>(actor_id_, link_token), std::move(data_));
+  data_.clear();
+  CHECK(empty());
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl/Scheduler-decl.h b/libs/tdlib/td/tdactor/td/actor/impl/Scheduler-decl.h
new file mode 100644
index 0000000000..4b51c102a5
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl/Scheduler-decl.h
@@ -0,0 +1,296 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/impl/Actor-decl.h"
+#include "td/actor/impl/ActorId-decl.h"
+#include "td/actor/impl/EventFull-decl.h"
+
+#include "td/utils/Closure.h"
+#include "td/utils/Heap.h"
+#include "td/utils/List.h"
+#include "td/utils/MovableValue.h"
+#include "td/utils/MpscPollableQueue.h"
+#include "td/utils/ObjectPool.h"
+#include "td/utils/port/EventFd.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/Poll.h"
+#include "td/utils/port/thread_local.h"
+#include "td/utils/Slice.h"
+#include "td/utils/type_traits.h"
+
+#include <functional>
+#include <map>
+#include <memory>
+#include <type_traits>
+#include <utility>
+
+namespace td {
+class ActorInfo;
+struct Send {
+  using Flags = uint32;
+  static const Flags immediate = 0x001;
+  static const Flags later = 0x002;
+  static const Flags later_weak = 0x004;
+};
+
+class Scheduler;
+class SchedulerGuard {
+ public:
+  explicit SchedulerGuard(Scheduler *scheduler);
+  ~SchedulerGuard();
+  SchedulerGuard(const SchedulerGuard &other) = delete;
+  SchedulerGuard &operator=(const SchedulerGuard &other) = delete;
+  SchedulerGuard(SchedulerGuard &&other) = default;
+  SchedulerGuard &operator=(SchedulerGuard &&other) = delete;
+
+ private:
+  MovableValue<bool> is_valid_ = true;
+  Scheduler *scheduler_;
+  ActorContext *save_context_;
+  Scheduler *save_scheduler_;
+  const char *save_tag_;
+};
+
+class Scheduler {
+ public:
+  class Callback {
+   public:
+    Callback() = default;
+    Callback(const Callback &) = delete;
+    Callback &operator=(const Callback &) = delete;
+    virtual ~Callback() = default;
+    virtual void on_finish() = 0;
+    virtual void register_at_finish(std::function<void()>) = 0;
+  };
+  Scheduler() = default;
+  Scheduler(const Scheduler &) = delete;
+  Scheduler &operator=(const Scheduler &) = delete;
+  Scheduler(Scheduler &&) = delete;
+  Scheduler &operator=(Scheduler &&) = delete;
+  ~Scheduler();
+
+  void init();
+  void init(int32 id, std::vector<std::shared_ptr<MpscPollableQueue<EventFull>>> outbound, Callback *callback);
+  void clear();
+
+  int32 sched_id() const;
+  int32 sched_count() const;
+
+  template <class ActorT, class... Args>
+  TD_WARN_UNUSED_RESULT ActorOwn<ActorT> create_actor(Slice name, Args &&... args);
+  template <class ActorT, class... Args>
+  TD_WARN_UNUSED_RESULT ActorOwn<ActorT> create_actor_on_scheduler(Slice name, int32 sched_id, Args &&... args);
+  template <class ActorT>
+  TD_WARN_UNUSED_RESULT ActorOwn<ActorT> register_actor(Slice name, ActorT *actor_ptr, int32 sched_id = -1);
+  template <class ActorT>
+  TD_WARN_UNUSED_RESULT ActorOwn<ActorT> register_actor(Slice name, unique_ptr<ActorT> actor_ptr, int32 sched_id = -1);
+
+  template <class ActorT>
+  TD_WARN_UNUSED_RESULT ActorOwn<ActorT> register_existing_actor(unique_ptr<ActorT> actor_ptr);
+
+  void send_to_scheduler(int32 sched_id, const ActorId<> &actor_id, Event &&event);
+  void send_to_other_scheduler(int32 sched_id, const ActorId<> &actor_id, Event &&event);
+
+  template <class EventT>
+  void send_lambda(ActorRef actor_ref, EventT &&lambda, Send::Flags flags = 0);
+
+  template <class EventT>
+  void send_closure(ActorRef actor_ref, EventT &&closure, Send::Flags flags = 0);
+
+  void send(ActorRef actor_ref, Event &&event, Send::Flags flags = 0);
+
+  void hack(const ActorId<> &actor_id, Event &&event) {
+    actor_id.get_actor_unsafe()->raw_event(event.data);
+  }
+  void before_tail_send(const ActorId<> &actor_id);
+
+  void subscribe(const Fd &fd, Fd::Flags flags = Fd::Write | Fd::Read);
+  void unsubscribe(const Fd &fd);
+  void unsubscribe_before_close(const Fd &fd);
+
+  void yield_actor(Actor *actor);
+  void stop_actor(Actor *actor);
+  void do_stop_actor(Actor *actor);
+  uint64 get_link_token(Actor *actor);
+  void migrate_actor(Actor *actor, int32 dest_sched_id);
+  void do_migrate_actor(Actor *actor, int32 dest_sched_id);
+  void start_migrate_actor(Actor *actor, int32 dest_sched_id);
+  void finish_migrate_actor(Actor *actor);
+
+  bool has_actor_timeout(const Actor *actor) const;
+  void set_actor_timeout_in(Actor *actor, double timeout);
+  void set_actor_timeout_at(Actor *actor, double timeout_at);
+  void cancel_actor_timeout(Actor *actor);
+
+  void finish();
+  void yield();
+  void run(double timeout);
+  void run_no_guard(double timeout);
+
+  void wakeup();
+
+  static Scheduler *instance();
+  static ActorContext *&context();
+  static void on_context_updated();
+
+  SchedulerGuard get_guard();
+
+ private:
+  static void set_scheduler(Scheduler *scheduler);
+  /*** ServiceActor ***/
+  class ServiceActor final : public Actor {
+   public:
+    void set_queue(std::shared_ptr<MpscPollableQueue<EventFull>> queues);
+    void start_up() override;
+
+   private:
+    std::shared_ptr<MpscPollableQueue<EventFull>> inbound_;
+    void loop() override;
+  };
+  friend class ServiceActor;
+
+  void do_custom_event(ActorInfo *actor, CustomEvent &event);
+  void do_event(ActorInfo *actor, Event &&event);
+
+  void enter_actor(ActorInfo *actor_info);
+  void exit_actor(ActorInfo *actor_info);
+
+  void yield_actor(ActorInfo *actor_info);
+  void stop_actor(ActorInfo *actor_info);
+  void do_stop_actor(ActorInfo *actor_info);
+  uint64 get_link_token(ActorInfo *actor_info);
+  void migrate_actor(ActorInfo *actor_info, int32 dest_sched_id);
+  void do_migrate_actor(ActorInfo *actor_info, int32 dest_sched_id);
+  void start_migrate_actor(ActorInfo *actor_info, int32 dest_sched_id);
+
+  bool has_actor_timeout(const ActorInfo *actor_info) const;
+  void set_actor_timeout_in(ActorInfo *actor_info, double timeout);
+  void set_actor_timeout_at(ActorInfo *actor_info, double timeout_at);
+  void cancel_actor_timeout(ActorInfo *actor_info);
+
+  void register_migrated_actor(ActorInfo *actor_info);
+  void add_to_mailbox(ActorInfo *actor_info, Event &&event);
+  void clear_mailbox(ActorInfo *actor_info);
+
+  template <class RunFuncT, class EventFuncT>
+  void flush_mailbox(ActorInfo *actor_info, const RunFuncT &run_func, const EventFuncT &event_func);
+
+  template <class RunFuncT, class EventFuncT>
+  void send_impl(const ActorId<> &actor_id, Send::Flags flags, const RunFuncT &run_func, const EventFuncT &event_func);
+
+  void inc_wait_generation();
+
+  double run_timeout();
+  void run_mailbox();
+  double run_events();
+  void run_poll(double timeout);
+
+  template <class ActorT>
+  ActorOwn<ActorT> register_actor_impl(Slice name, ActorT *actor_ptr, Actor::Deleter deleter, int32 sched_id);
+  void destroy_actor(ActorInfo *actor_info);
+
+  static TD_THREAD_LOCAL Scheduler *scheduler_;
+  static TD_THREAD_LOCAL ActorContext *context_;
+
+  Callback *callback_ = nullptr;
+  std::unique_ptr<ObjectPool<ActorInfo>> actor_info_pool_;
+
+  int32 actor_count_;
+  ListNode pending_actors_list_;
+  ListNode ready_actors_list_;
+  KHeap<double> timeout_queue_;
+
+  std::map<ActorInfo *, std::vector<Event>> pending_events_;
+
+#if !TD_THREAD_UNSUPPORTED && !TD_EVENTFD_UNSUPPORTED
+  EventFd event_fd_;
+#endif
+  ServiceActor service_actor_;
+  Poll poll_;
+
+  bool yield_flag_;
+  bool has_guard_ = false;
+  bool close_flag_ = false;
+
+  uint32 wait_generation_ = 0;
+  int32 sched_id_;
+  int32 sched_n_;
+  std::shared_ptr<MpscPollableQueue<EventFull>> inbound_queue_;
+  std::vector<std::shared_ptr<MpscPollableQueue<EventFull>>> outbound_queues_;
+
+  std::shared_ptr<ActorContext> save_context_;
+
+  struct EventContext {
+    int32 dest_sched_id;
+    enum Flags { Stop = 1, Migrate = 2 };
+    int32 flags{0};
+    uint64 link_token;
+
+    ActorInfo *actor_info;
+  };
+  EventContext *event_context_ptr_;
+
+  friend class GlobalScheduler;
+  friend class SchedulerGuard;
+  friend class EventGuard;
+};
+
+/*** Interface to current scheduler ***/
+void subscribe(const Fd &fd, Fd::Flags flags = Fd::Write | Fd::Read);
+void unsubscribe(const Fd &fd);
+void unsubscribe_before_close(const Fd &fd);
+
+template <class ActorT, class... Args>
+TD_WARN_UNUSED_RESULT ActorOwn<ActorT> create_actor(Slice name, Args &&... args);
+template <class ActorT, class... Args>
+TD_WARN_UNUSED_RESULT ActorOwn<ActorT> create_actor_on_scheduler(Slice name, int32 sched_id, Args &&... args);
+template <class ActorT>
+TD_WARN_UNUSED_RESULT ActorOwn<ActorT> register_actor(Slice name, ActorT *actor_ptr, int32 sched_id = -1);
+template <class ActorT>
+TD_WARN_UNUSED_RESULT ActorOwn<ActorT> register_actor(Slice name, unique_ptr<ActorT> actor_ptr, int32 sched_id = -1);
+
+template <class ActorT>
+TD_WARN_UNUSED_RESULT ActorOwn<ActorT> register_existing_actor(unique_ptr<ActorT> actor_ptr);
+
+template <class ActorIdT, class FunctionT, class... ArgsT>
+void send_closure(ActorIdT &&actor_id, FunctionT function, ArgsT &&... args) {
+  using ActorT = typename std::decay_t<ActorIdT>::ActorT;
+  using FunctionClassT = member_function_class_t<FunctionT>;
+  static_assert(std::is_base_of<FunctionClassT, ActorT>::value, "unsafe send_closure");
+
+  Scheduler::instance()->send_closure(std::forward<ActorIdT>(actor_id),
+                                      create_immediate_closure(function, std::forward<ArgsT>(args)...));
+}
+
+template <class ActorIdT, class FunctionT, class... ArgsT>
+void send_closure_later(ActorIdT &&actor_id, FunctionT function, ArgsT &&... args) {
+  using ActorT = typename std::decay_t<ActorIdT>::ActorT;
+  using FunctionClassT = member_function_class_t<FunctionT>;
+  static_assert(std::is_base_of<FunctionClassT, ActorT>::value, "unsafe send_closure");
+
+  Scheduler::instance()->send(std::forward<ActorIdT>(actor_id),
+                              Event::delayed_closure(function, std::forward<ArgsT>(args)...), Send::later);
+}
+
+template <class... ArgsT>
+void send_lambda(ActorRef actor_ref, ArgsT &&... args) {
+  Scheduler::instance()->send_lambda(actor_ref, std::forward<ArgsT>(args)...);
+}
+
+template <class... ArgsT>
+void send_event(ActorRef actor_ref, ArgsT &&... args) {
+  Scheduler::instance()->send(actor_ref, std::forward<ArgsT>(args)...);
+}
+
+template <class... ArgsT>
+void send_event_later(ActorRef actor_ref, ArgsT &&... args) {
+  Scheduler::instance()->send(actor_ref, std::forward<ArgsT>(args)..., Send::later);
+}
+
+void yield_scheduler();
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl/Scheduler.cpp b/libs/tdlib/td/tdactor/td/actor/impl/Scheduler.cpp
new file mode 100644
index 0000000000..479e419d62
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl/Scheduler.cpp
@@ -0,0 +1,496 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/actor/impl/Scheduler.h"
+
+#include "td/actor/impl/Actor.h"
+#include "td/actor/impl/ActorId.h"
+#include "td/actor/impl/ActorInfo.h"
+#include "td/actor/impl/Event.h"
+#include "td/actor/impl/EventFull.h"
+
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/List.h"
+#include "td/utils/logging.h"
+#include "td/utils/ObjectPool.h"
+#include "td/utils/port/thread_local.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Time.h"
+
+#include <functional>
+#include <utility>
+
+namespace td {
+
+TD_THREAD_LOCAL Scheduler *Scheduler::scheduler_;   // static zero-initialized
+TD_THREAD_LOCAL ActorContext *Scheduler::context_;  // static zero-initialized
+
+Scheduler::~Scheduler() {
+  clear();
+}
+
+Scheduler *Scheduler::instance() {
+  return scheduler_;
+}
+
+ActorContext *&Scheduler::context() {
+  return context_;
+}
+
+void Scheduler::on_context_updated() {
+  LOG_TAG = context_->tag_;
+}
+
+void Scheduler::set_scheduler(Scheduler *scheduler) {
+  scheduler_ = scheduler;
+}
+
+void Scheduler::ServiceActor::start_up() {
+#if TD_THREAD_UNSUPPORTED || TD_EVENTFD_UNSUPPORTED
+  CHECK(!inbound_);
+#else
+  if (!inbound_) {
+    return;
+  }
+  auto &fd = inbound_->reader_get_event_fd();
+
+  fd.get_fd().set_observer(this);
+  ::td::subscribe(fd.get_fd(), Fd::Read);
+  yield();
+#endif
+}
+
+void Scheduler::ServiceActor::loop() {
+  auto &queue = inbound_;
+  int ready_n = queue->reader_wait_nonblock();
+  if (ready_n == 0) {
+    return;
+  }
+  while (ready_n-- > 0) {
+    EventFull event = queue->reader_get_unsafe();
+    if (event.actor_id().empty()) {
+      Scheduler::instance()->register_migrated_actor(static_cast<ActorInfo *>(event.data().data.ptr));
+    } else {
+      VLOG(actor) << "Receive " << event.data();
+      finish_migrate(event.data());
+      event.try_emit();
+    }
+  }
+  queue->reader_flush();
+  yield();
+}
+
+/*** SchedlerGuard ***/
+SchedulerGuard::SchedulerGuard(Scheduler *scheduler) : scheduler_(scheduler) {
+  CHECK(!scheduler_->has_guard_);
+  scheduler_->has_guard_ = true;
+  save_scheduler_ = Scheduler::instance();
+  Scheduler::set_scheduler(scheduler_);
+
+  // Scheduler::context() must be not null
+  save_context_ = scheduler_->save_context_.get();
+  save_tag_ = LOG_TAG;
+  LOG_TAG = save_context_->tag_;
+  std::swap(save_context_, Scheduler::context());
+}
+
+SchedulerGuard::~SchedulerGuard() {
+  if (is_valid_.get()) {
+    std::swap(save_context_, scheduler_->context());
+    Scheduler::set_scheduler(save_scheduler_);
+    CHECK(scheduler_->has_guard_);
+    scheduler_->has_guard_ = false;
+    LOG_TAG = save_tag_;
+  }
+}
+
+/*** EventGuard ***/
+EventGuard::EventGuard(Scheduler *scheduler, ActorInfo *actor_info) : scheduler_(scheduler) {
+  actor_info->start_run();
+  event_context_.actor_info = actor_info;
+  event_context_ptr_ = &event_context_;
+
+  save_context_ = actor_info->get_context();
+#ifdef TD_DEBUG
+  save_log_tag2_ = actor_info->get_name().c_str();
+#endif
+  swap_context(actor_info);
+}
+
+EventGuard::~EventGuard() {
+  auto info = event_context_.actor_info;
+  auto node = info->get_list_node();
+  node->remove();
+  if (info->mailbox_.empty()) {
+    scheduler_->pending_actors_list_.put(node);
+  } else {
+    scheduler_->ready_actors_list_.put(node);
+  }
+  info->finish_run();
+  swap_context(info);
+  CHECK(info->is_lite() || save_context_ == info->get_context());
+#ifdef TD_DEBUG
+  CHECK(info->is_lite() || save_log_tag2_ == info->get_name().c_str());
+#endif
+  if (event_context_.flags & Scheduler::EventContext::Stop) {
+    scheduler_->do_stop_actor(info);
+    return;
+  }
+  if (event_context_.flags & Scheduler::EventContext::Migrate) {
+    scheduler_->do_migrate_actor(info, event_context_.dest_sched_id);
+  }
+}
+
+void EventGuard::swap_context(ActorInfo *info) {
+  std::swap(scheduler_->event_context_ptr_, event_context_ptr_);
+
+  if (info->is_lite()) {
+    return;
+  }
+
+#ifdef TD_DEBUG
+  std::swap(LOG_TAG2, save_log_tag2_);
+#endif
+
+  auto *current_context_ptr = &Scheduler::context();
+  if (save_context_ != *current_context_ptr) {
+    std::swap(save_context_, *current_context_ptr);
+    Scheduler::on_context_updated();
+  }
+}
+
+void Scheduler::init(int32 id, std::vector<std::shared_ptr<MpscPollableQueue<EventFull>>> outbound,
+                     Callback *callback) {
+  save_context_ = std::make_shared<ActorContext>();
+  save_context_->this_ptr_ = save_context_;
+  save_context_->tag_ = LOG_TAG;
+
+  auto guard = get_guard();
+
+  callback_ = callback;
+  actor_info_pool_ = make_unique<ObjectPool<ActorInfo>>();
+
+  yield_flag_ = false;
+  actor_count_ = 0;
+  sched_id_ = 0;
+
+  poll_.init();
+
+#if !TD_THREAD_UNSUPPORTED && !TD_EVENTFD_UNSUPPORTED
+  event_fd_.init();
+  subscribe(event_fd_.get_fd(), Fd::Read);
+#endif
+
+  if (!outbound.empty()) {
+    inbound_queue_ = std::move(outbound[id]);
+  }
+  outbound_queues_ = std::move(outbound);
+  sched_id_ = id;
+  sched_n_ = static_cast<int32>(outbound_queues_.size());
+  service_actor_.set_queue(inbound_queue_);
+  register_actor("ServiceActor", &service_actor_).release();
+}
+
+void Scheduler::clear() {
+  if (service_actor_.empty()) {
+    return;
+  }
+  close_flag_ = true;
+  auto guard = get_guard();
+
+  // Stop all actors
+  if (!service_actor_.empty()) {
+    service_actor_.do_stop();
+  }
+  while (!pending_actors_list_.empty()) {
+    auto actor_info = ActorInfo::from_list_node(pending_actors_list_.get());
+    do_stop_actor(actor_info);
+  }
+  while (!ready_actors_list_.empty()) {
+    auto actor_info = ActorInfo::from_list_node(ready_actors_list_.get());
+    do_stop_actor(actor_info);
+  }
+  LOG_IF(FATAL, !ready_actors_list_.empty()) << ActorInfo::from_list_node(ready_actors_list_.next)->get_name();
+  CHECK(ready_actors_list_.empty());
+  poll_.clear();
+
+#if !TD_THREAD_UNSUPPORTED && !TD_EVENTFD_UNSUPPORTED
+  if (!event_fd_.empty()) {
+    event_fd_.close();
+  }
+#endif
+
+  if (callback_) {
+    // can't move lambda with unique_ptr inside into std::function
+    auto ptr = actor_info_pool_.release();
+    callback_->register_at_finish([=]() { delete ptr; });
+  } else {
+    actor_info_pool_.reset();
+  }
+}
+
+void Scheduler::do_event(ActorInfo *actor_info, Event &&event) {
+  event_context_ptr_->link_token = event.link_token;
+  auto actor = actor_info->get_actor_unsafe();
+  switch (event.type) {
+    case Event::Type::Start: {
+      VLOG(actor) << *actor_info << " Event::Start";
+      actor->start_up();
+      break;
+    }
+    case Event::Type::Stop: {
+      VLOG(actor) << *actor_info << " Event::Stop";
+      actor->tear_down();
+      break;
+    }
+    case Event::Type::Yield: {
+      VLOG(actor) << *actor_info << " Event::Yield";
+      actor->wakeup();
+      break;
+    }
+    case Event::Type::Hangup: {
+      auto token = get_link_token(actor);
+      VLOG(actor) << *actor_info << " Event::Hangup " << tag("token", format::as_hex(token));
+      if (token != 0) {
+        actor->hangup_shared();
+      } else {
+        actor->hangup();
+      }
+      break;
+    }
+    case Event::Type::Timeout: {
+      VLOG(actor) << *actor_info << " Event::Timeout";
+      actor->timeout_expired();
+      break;
+    }
+    case Event::Type::Raw: {
+      VLOG(actor) << *actor_info << " Event::Raw";
+      actor->raw_event(event.data);
+      break;
+    }
+    case Event::Type::Custom: {
+      do_custom_event(actor_info, *event.data.custom_event);
+      break;
+    }
+    case Event::Type::NoType: {
+      UNREACHABLE();
+      break;
+    }
+  }
+  // can't clear event here. It may be already destroyed during destory_actor
+}
+
+void Scheduler::register_migrated_actor(ActorInfo *actor_info) {
+  VLOG(actor) << "Register migrated actor: " << tag("name", *actor_info) << tag("ptr", actor_info)
+              << tag("actor_count", actor_count_);
+  actor_count_++;
+  CHECK(actor_info->is_migrating());
+  CHECK(sched_id_ == actor_info->migrate_dest());
+  // CHECK(!actor_info->is_running());
+  actor_info->finish_migrate();
+  for (auto &event : actor_info->mailbox_) {
+    finish_migrate(event);
+  }
+  auto it = pending_events_.find(actor_info);
+  if (it != pending_events_.end()) {
+    actor_info->mailbox_.insert(actor_info->mailbox_.end(), make_move_iterator(begin(it->second)),
+                                make_move_iterator(end(it->second)));
+    pending_events_.erase(it);
+  }
+  if (actor_info->mailbox_.empty()) {
+    pending_actors_list_.put(actor_info->get_list_node());
+  } else {
+    ready_actors_list_.put(actor_info->get_list_node());
+  }
+  actor_info->get_actor_unsafe()->on_finish_migrate();
+}
+
+void Scheduler::send_to_other_scheduler(int32 sched_id, const ActorId<> &actor_id, Event &&event) {
+  if (sched_id < sched_count()) {
+    auto actor_info = actor_id.get_actor_info();
+    if (actor_info) {
+      VLOG(actor) << "Send to " << *actor_info << " on scheduler " << sched_id << ": " << event;
+    } else {
+      VLOG(actor) << "Send to scheduler " << sched_id << ": " << event;
+    }
+    start_migrate(event, sched_id);
+    outbound_queues_[sched_id]->writer_put(EventCreator::event_unsafe(actor_id, std::move(event)));
+    outbound_queues_[sched_id]->writer_flush();
+  }
+}
+
+void Scheduler::add_to_mailbox(ActorInfo *actor_info, Event &&event) {
+  if (!actor_info->is_running()) {
+    auto node = actor_info->get_list_node();
+    node->remove();
+    ready_actors_list_.put(node);
+  }
+  VLOG(actor) << "Add to mailbox: " << *actor_info << " " << event;
+  actor_info->mailbox_.push_back(std::move(event));
+}
+
+void Scheduler::do_stop_actor(Actor *actor) {
+  return do_stop_actor(actor->get_info());
+}
+void Scheduler::do_stop_actor(ActorInfo *actor_info) {
+  CHECK(!actor_info->is_migrating());
+  CHECK(actor_info->migrate_dest() == sched_id_) << actor_info->migrate_dest() << " " << sched_id_;
+  ObjectPool<ActorInfo>::OwnerPtr owner_ptr;
+  if (!actor_info->is_lite()) {
+    EventGuard guard(this, actor_info);
+    do_event(actor_info, Event::stop());
+    owner_ptr = actor_info->get_actor_unsafe()->clear();
+    // Actor context is visible in destructor
+    actor_info->destroy_actor();
+    event_context_ptr_->flags = 0;
+  } else {
+    owner_ptr = actor_info->get_actor_unsafe()->clear();
+  }
+  destroy_actor(actor_info);
+}
+
+void Scheduler::migrate_actor(Actor *actor, int32 dest_sched_id) {
+  migrate_actor(actor->get_info(), dest_sched_id);
+}
+void Scheduler::migrate_actor(ActorInfo *actor_info, int32 dest_sched_id) {
+  CHECK(event_context_ptr_->actor_info == actor_info);
+  if (sched_id_ == dest_sched_id) {
+    return;
+  }
+  event_context_ptr_->flags |= EventContext::Migrate;
+  event_context_ptr_->dest_sched_id = dest_sched_id;
+}
+
+void Scheduler::do_migrate_actor(Actor *actor, int32 dest_sched_id) {
+  do_migrate_actor(actor->get_info(), dest_sched_id);
+}
+void Scheduler::do_migrate_actor(ActorInfo *actor_info, int32 dest_sched_id) {
+#if TD_THREAD_UNSUPPORTED || TD_EVENTFD_UNSUPPORTED
+  dest_sched_id = 0;
+#endif
+  if (sched_id_ == dest_sched_id) {
+    return;
+  }
+  start_migrate_actor(actor_info, dest_sched_id);
+  send_to_other_scheduler(dest_sched_id, ActorId<>(), Event::raw(actor_info));
+}
+
+void Scheduler::start_migrate_actor(Actor *actor, int32 dest_sched_id) {
+  start_migrate_actor(actor->get_info(), dest_sched_id);
+}
+void Scheduler::start_migrate_actor(ActorInfo *actor_info, int32 dest_sched_id) {
+  VLOG(actor) << "Start migrate actor: " << tag("name", actor_info) << tag("ptr", actor_info)
+              << tag("actor_count", actor_count_);
+  actor_count_--;
+  CHECK(actor_count_ >= 0);
+  actor_info->get_actor_unsafe()->on_start_migrate(dest_sched_id);
+  for (auto &event : actor_info->mailbox_) {
+    start_migrate(event, dest_sched_id);
+  }
+  actor_info->start_migrate(dest_sched_id);
+  actor_info->get_list_node()->remove();
+  cancel_actor_timeout(actor_info);
+}
+
+void Scheduler::set_actor_timeout_in(ActorInfo *actor_info, double timeout) {
+  if (timeout > 1e10) {
+    timeout = 1e10;
+  }
+  if (timeout < 0) {
+    timeout = 0;
+  }
+  double expire_at = Time::now() + timeout;
+  set_actor_timeout_at(actor_info, expire_at);
+}
+
+void Scheduler::set_actor_timeout_at(ActorInfo *actor_info, double timeout_at) {
+  HeapNode *heap_node = actor_info->get_heap_node();
+  VLOG(actor) << "set actor " << *actor_info << " " << tag("timeout", timeout_at) << timeout_at - Time::now_cached();
+  if (heap_node->in_heap()) {
+    timeout_queue_.fix(timeout_at, heap_node);
+  } else {
+    timeout_queue_.insert(timeout_at, heap_node);
+  }
+}
+
+void Scheduler::run_poll(double timeout) {
+  // LOG(DEBUG) << "run poll [timeout:" << format::as_time(timeout) << "]";
+  // we can't wait for less than 1ms
+  poll_.run(static_cast<int32>(timeout * 1000 + 1));
+
+#if !TD_THREAD_UNSUPPORTED && !TD_EVENTFD_UNSUPPORTED
+  if (can_read(event_fd_.get_fd())) {
+    std::atomic_thread_fence(std::memory_order_acquire);
+    event_fd_.acquire();
+  }
+#endif
+}
+
+void Scheduler::run_mailbox() {
+  VLOG(actor) << "run mailbox : begin";
+  ListNode actors_list = std::move(ready_actors_list_);
+  while (!actors_list.empty()) {
+    ListNode *node = actors_list.get();
+    CHECK(node);
+    auto actor_info = ActorInfo::from_list_node(node);
+    inc_wait_generation();
+    flush_mailbox(actor_info, static_cast<void (*)(ActorInfo *)>(nullptr), static_cast<Event (*)()>(nullptr));
+  }
+  VLOG(actor) << "run mailbox : finish " << actor_count_;
+
+  //Useful for debug, but O(ActorsCount) check
+
+  //int cnt = 0;
+  //for (ListNode *end = &pending_actors_list_, *it = pending_actors_list_.next; it != end; it = it->next) {
+  //cnt++;
+  //auto actor_info = ActorInfo::from_list_node(it);
+  //LOG(ERROR) << *actor_info;
+  //CHECK(actor_info->mailbox_.empty());
+  //CHECK(!actor_info->is_running());
+  //}
+  //for (ListNode *end = &ready_actors_list_, *it = ready_actors_list_.next; it != end; it = it->next) {
+  //auto actor_info = ActorInfo::from_list_node(it);
+  //LOG(ERROR) << *actor_info;
+  //cnt++;
+  //}
+  //CHECK(cnt == actor_count_) << cnt << " vs " << actor_count_;
+}
+
+double Scheduler::run_timeout() {
+  double now = Time::now();
+  while (!timeout_queue_.empty() && timeout_queue_.top_key() < now) {
+    HeapNode *node = timeout_queue_.pop();
+    ActorInfo *actor_info = ActorInfo::from_heap_node(node);
+    inc_wait_generation();
+    send(actor_info->actor_id(), Event::timeout(), Send::immediate);
+  }
+  if (timeout_queue_.empty()) {
+    return 10000;
+  }
+  double timeout = timeout_queue_.top_key() - now;
+  // LOG(DEBUG) << "Timeout [cnt:" << timeout_queue_.size() << "] in " << format::as_time(timeout);
+  return timeout;
+}
+
+void Scheduler::run_no_guard(double timeout) {
+  CHECK(has_guard_);
+  SCOPE_EXIT {
+    yield_flag_ = false;
+  };
+
+  double next_timeout = run_events();
+  if (next_timeout < timeout) {
+    timeout = next_timeout;
+  }
+  if (yield_flag_) {
+    return;
+  }
+  run_poll(timeout);
+  run_events();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl/Scheduler.h b/libs/tdlib/td/tdactor/td/actor/impl/Scheduler.h
new file mode 100644
index 0000000000..7edf3f1d2d
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl/Scheduler.h
@@ -0,0 +1,397 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/impl/ActorInfo-decl.h"
+#include "td/actor/impl/Scheduler-decl.h"
+
+#include "td/utils/format.h"
+#include "td/utils/Heap.h"
+#include "td/utils/logging.h"
+#include "td/utils/MpscPollableQueue.h"
+#include "td/utils/ObjectPool.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/Slice.h"
+
+#include <atomic>
+#include <memory>
+#include <tuple>
+#include <utility>
+
+namespace td {
+
+/*** ServiceActor ***/
+inline void Scheduler::ServiceActor::set_queue(std::shared_ptr<MpscPollableQueue<EventFull>> queues) {
+  inbound_ = std::move(queues);
+}
+
+/*** EventGuard ***/
+class EventGuard {
+ public:
+  EventGuard(Scheduler *scheduler, ActorInfo *actor_info);
+
+  bool can_run() const {
+    return event_context_.flags == 0;
+  }
+
+  EventGuard(const EventGuard &other) = delete;
+  EventGuard &operator=(const EventGuard &other) = delete;
+  EventGuard(EventGuard &&other) = delete;
+  EventGuard &operator=(EventGuard &&other) = delete;
+  ~EventGuard();
+
+ private:
+  Scheduler::EventContext event_context_;
+  Scheduler::EventContext *event_context_ptr_;
+  Scheduler *scheduler_;
+  ActorContext *save_context_;
+  const char *save_log_tag2_;
+
+  void swap_context(ActorInfo *info);
+};
+
+/*** Scheduler ***/
+inline SchedulerGuard Scheduler::get_guard() {
+  return SchedulerGuard(this);
+}
+
+inline void Scheduler::init() {
+  init(0, {}, nullptr);
+}
+
+inline int32 Scheduler::sched_id() const {
+  return sched_id_;
+}
+inline int32 Scheduler::sched_count() const {
+  return sched_n_;
+}
+
+template <class ActorT, class... Args>
+ActorOwn<ActorT> Scheduler::create_actor(Slice name, Args &&... args) {
+  return register_actor_impl(name, new ActorT(std::forward<Args>(args)...), Actor::Deleter::Destroy, sched_id_);
+}
+
+template <class ActorT, class... Args>
+ActorOwn<ActorT> Scheduler::create_actor_on_scheduler(Slice name, int32 sched_id, Args &&... args) {
+  return register_actor_impl(name, new ActorT(std::forward<Args>(args)...), Actor::Deleter::Destroy, sched_id);
+}
+
+template <class ActorT>
+ActorOwn<ActorT> Scheduler::register_actor(Slice name, ActorT *actor_ptr, int32 sched_id) {
+  return register_actor_impl(name, actor_ptr, Actor::Deleter::None, sched_id);
+}
+
+template <class ActorT>
+ActorOwn<ActorT> Scheduler::register_actor(Slice name, unique_ptr<ActorT> actor_ptr, int32 sched_id) {
+  return register_actor_impl(name, actor_ptr.release(), Actor::Deleter::Destroy, sched_id);
+}
+
+template <class ActorT>
+ActorOwn<ActorT> Scheduler::register_actor_impl(Slice name, ActorT *actor_ptr, Actor::Deleter deleter, int32 sched_id) {
+  if (sched_id == -1) {
+    sched_id = sched_id_;
+  }
+#if TD_THREAD_UNSUPPORTED || TD_EVENTFD_UNSUPPORTED
+  sched_id = 0;
+#endif
+  CHECK(sched_id == sched_id_ || (0 <= sched_id && sched_id < static_cast<int32>(outbound_queues_.size()))) << sched_id;
+  auto info = actor_info_pool_->create_empty();
+  VLOG(actor) << "Create actor: " << tag("name", name) << tag("ptr", *info) << tag("context", context())
+              << tag("this", this) << tag("actor_count", actor_count_);
+  actor_count_++;
+  auto weak_info = info.get_weak();
+  auto actor_info = info.get();
+  info->init(sched_id_, name, std::move(info), static_cast<Actor *>(actor_ptr), deleter, ActorTraits<ActorT>::is_lite);
+
+  ActorId<ActorT> actor_id = weak_info->actor_id(actor_ptr);
+  if (sched_id != sched_id_) {
+    send(actor_id, Event::start(), Send::later_weak);
+    do_migrate_actor(actor_info, sched_id);
+  } else {
+    pending_actors_list_.put(weak_info->get_list_node());
+    if (!ActorTraits<ActorT>::is_lite) {
+      send(actor_id, Event::start(), Send::later_weak);
+    }
+  }
+
+  return ActorOwn<ActorT>(actor_id);
+}
+
+template <class ActorT>
+ActorOwn<ActorT> Scheduler::register_existing_actor(std::unique_ptr<ActorT> actor_ptr) {
+  CHECK(!actor_ptr->empty());
+  auto actor_info = actor_ptr->get_info();
+  CHECK(actor_info->migrate_dest_flag_atomic().first == sched_id_);
+  return actor_info->transfer_ownership_to_scheduler(std::move(actor_ptr));
+}
+
+inline void Scheduler::destroy_actor(ActorInfo *actor_info) {
+  VLOG(actor) << "Destroy actor: " << tag("name", *actor_info) << tag("ptr", actor_info)
+              << tag("actor_count", actor_count_);
+
+  CHECK(actor_info->migrate_dest() == sched_id_) << actor_info->migrate_dest() << " " << sched_id_;
+  cancel_actor_timeout(actor_info);
+  actor_info->get_list_node()->remove();
+  // called by ObjectPool
+  // actor_info->clear();
+  actor_count_--;
+  CHECK(actor_count_ >= 0);
+}
+
+inline void Scheduler::do_custom_event(ActorInfo *actor_info, CustomEvent &event) {
+  VLOG(actor) << *actor_info << " Event::Custom";
+  event.run(actor_info->get_actor_unsafe());
+}
+
+template <class RunFuncT, class EventFuncT>
+void Scheduler::flush_mailbox(ActorInfo *actor_info, const RunFuncT &run_func, const EventFuncT &event_func) {
+  auto &mailbox = actor_info->mailbox_;
+  size_t mailbox_size = mailbox.size();
+  CHECK(mailbox_size != 0);
+  EventGuard guard(this, actor_info);
+  size_t i = 0;
+  for (; i < mailbox_size && guard.can_run(); i++) {
+    do_event(actor_info, std::move(mailbox[i]));
+  }
+  if (run_func) {
+    if (guard.can_run()) {
+      (*run_func)(actor_info);
+    } else {
+      mailbox.insert(begin(mailbox) + i, (*event_func)());
+    }
+  }
+  mailbox.erase(begin(mailbox), begin(mailbox) + i);
+}
+
+inline void Scheduler::send_to_scheduler(int32 sched_id, const ActorId<> &actor_id, Event &&event) {
+  if (sched_id == sched_id_) {
+    ActorInfo *actor_info = actor_id.get_actor_info();
+    pending_events_[actor_info].push_back(std::move(event));
+  } else {
+    send_to_other_scheduler(sched_id, actor_id, std::move(event));
+  }
+}
+
+inline void Scheduler::before_tail_send(const ActorId<> &actor_id) {
+  // TODO
+}
+
+inline void Scheduler::inc_wait_generation() {
+  wait_generation_++;
+}
+
+template <class RunFuncT, class EventFuncT>
+void Scheduler::send_impl(const ActorId<> &actor_id, Send::Flags flags, const RunFuncT &run_func,
+                          const EventFuncT &event_func) {
+  CHECK(has_guard_);
+  ActorInfo *actor_info = actor_id.get_actor_info();
+  if (unlikely(actor_info == nullptr || close_flag_)) {
+    // LOG(ERROR) << "Invalid actor id";
+    return;
+  }
+
+  CHECK(actor_info != nullptr);
+  int32 actor_sched_id;
+  bool is_migrating;
+  std::tie(actor_sched_id, is_migrating) = actor_info->migrate_dest_flag_atomic();
+  bool on_current_sched = !is_migrating && sched_id_ == actor_sched_id;
+
+  if (likely(!(flags & Send::later) && !(flags & Send::later_weak) && on_current_sched && !actor_info->is_running() &&
+             !actor_info->must_wait(wait_generation_))) {  // run immediately
+    if (likely(actor_info->mailbox_.empty())) {
+      EventGuard guard(this, actor_info);
+      run_func(actor_info);
+    } else {
+      flush_mailbox(actor_info, &run_func, &event_func);
+    }
+  } else {
+    if (on_current_sched) {
+      add_to_mailbox(actor_info, event_func());
+      if (flags & Send::later) {
+        actor_info->set_wait_generation(wait_generation_);
+      }
+    } else {
+      send_to_scheduler(actor_sched_id, actor_id, event_func());
+    }
+  }
+}
+
+template <class EventT>
+void Scheduler::send_lambda(ActorRef actor_ref, EventT &&lambda, Send::Flags flags) {
+  return send_impl(actor_ref.get(), flags,
+                   [&](ActorInfo *actor_info) {
+                     event_context_ptr_->link_token = actor_ref.token();
+                     lambda();
+                   },
+                   [&]() {
+                     auto event = Event::lambda(std::forward<EventT>(lambda));
+                     event.set_link_token(actor_ref.token());
+                     return std::move(event);
+                   });
+}
+
+template <class EventT>
+void Scheduler::send_closure(ActorRef actor_ref, EventT &&closure, Send::Flags flags) {
+  return send_impl(actor_ref.get(), flags,
+                   [&](ActorInfo *actor_info) {
+                     event_context_ptr_->link_token = actor_ref.token();
+                     closure.run(static_cast<typename EventT::ActorType *>(actor_info->get_actor_unsafe()));
+                   },
+                   [&]() {
+                     auto event = Event::immediate_closure(std::forward<EventT>(closure));
+                     event.set_link_token(actor_ref.token());
+                     return std::move(event);
+                   });
+}
+
+inline void Scheduler::send(ActorRef actor_ref, Event &&event, Send::Flags flags) {
+  event.set_link_token(actor_ref.token());
+  return send_impl(actor_ref.get(), flags, [&](ActorInfo *actor_info) { do_event(actor_info, std::move(event)); },
+                   [&]() { return std::move(event); });
+}
+
+inline void Scheduler::subscribe(const Fd &fd, Fd::Flags flags) {
+  poll_.subscribe(fd, flags);
+}
+
+inline void Scheduler::unsubscribe(const Fd &fd) {
+  poll_.unsubscribe(fd);
+}
+
+inline void Scheduler::unsubscribe_before_close(const Fd &fd) {
+  poll_.unsubscribe_before_close(fd);
+}
+
+inline void Scheduler::yield_actor(Actor *actor) {
+  yield_actor(actor->get_info());
+}
+inline void Scheduler::yield_actor(ActorInfo *actor_info) {
+  send(actor_info->actor_id(), Event::yield(), Send::later_weak);
+}
+
+inline void Scheduler::stop_actor(Actor *actor) {
+  stop_actor(actor->get_info());
+}
+inline void Scheduler::stop_actor(ActorInfo *actor_info) {
+  CHECK(event_context_ptr_->actor_info == actor_info);
+  event_context_ptr_->flags |= EventContext::Stop;
+}
+
+inline uint64 Scheduler::get_link_token(Actor *actor) {
+  return get_link_token(actor->get_info());
+}
+inline uint64 Scheduler::get_link_token(ActorInfo *actor_info) {
+  CHECK(event_context_ptr_->actor_info == actor_info);
+  return event_context_ptr_->link_token;
+}
+
+inline void Scheduler::finish_migrate_actor(Actor *actor) {
+  register_migrated_actor(actor->get_info());
+}
+
+inline bool Scheduler::has_actor_timeout(const Actor *actor) const {
+  return has_actor_timeout(actor->get_info());
+}
+inline void Scheduler::set_actor_timeout_in(Actor *actor, double timeout) {
+  set_actor_timeout_in(actor->get_info(), timeout);
+}
+inline void Scheduler::set_actor_timeout_at(Actor *actor, double timeout_at) {
+  set_actor_timeout_at(actor->get_info(), timeout_at);
+}
+inline void Scheduler::cancel_actor_timeout(Actor *actor) {
+  cancel_actor_timeout(actor->get_info());
+}
+
+inline bool Scheduler::has_actor_timeout(const ActorInfo *actor_info) const {
+  const HeapNode *heap_node = actor_info->get_heap_node();
+  return heap_node->in_heap();
+}
+
+inline void Scheduler::cancel_actor_timeout(ActorInfo *actor_info) {
+  HeapNode *heap_node = actor_info->get_heap_node();
+  if (heap_node->in_heap()) {
+    timeout_queue_.erase(heap_node);
+  }
+}
+
+inline void Scheduler::finish() {
+  if (callback_) {
+    callback_->on_finish();
+  }
+  yield();
+}
+
+inline void Scheduler::yield() {
+  yield_flag_ = true;
+}
+
+inline void Scheduler::wakeup() {
+  std::atomic_thread_fence(std::memory_order_release);
+#if !TD_THREAD_UNSUPPORTED && !TD_EVENTFD_UNSUPPORTED
+  event_fd_.release();
+#endif
+}
+
+inline double Scheduler::run_events() {
+  double res;
+  VLOG(actor) << "run events " << sched_id_ << " " << tag("pending", pending_events_.size())
+              << tag("actors", actor_count_);
+  do {
+    run_mailbox();
+    res = run_timeout();
+  } while (!ready_actors_list_.empty());
+  return res;
+}
+
+inline void Scheduler::run(double timeout) {
+  auto guard = get_guard();
+  run_no_guard(timeout);
+}
+
+/*** Interface to current scheduler ***/
+inline void subscribe(const Fd &fd, Fd::Flags flags) {
+  Scheduler::instance()->subscribe(fd, flags);
+}
+
+inline void unsubscribe(const Fd &fd) {
+  Scheduler::instance()->unsubscribe(fd);
+}
+
+inline void unsubscribe_before_close(const Fd &fd) {
+  Scheduler::instance()->unsubscribe_before_close(fd);
+}
+
+template <class ActorT, class... Args>
+ActorOwn<ActorT> create_actor(Slice name, Args &&... args) {
+  return Scheduler::instance()->create_actor<ActorT>(name, std::forward<Args>(args)...);
+}
+
+template <class ActorT, class... Args>
+ActorOwn<ActorT> create_actor_on_scheduler(Slice name, int32 sched_id, Args &&... args) {
+  return Scheduler::instance()->create_actor_on_scheduler<ActorT>(name, sched_id, std::forward<Args>(args)...);
+}
+
+template <class ActorT>
+ActorOwn<ActorT> register_actor(Slice name, ActorT *actor_ptr, int32 sched_id) {
+  return Scheduler::instance()->register_actor<ActorT>(name, actor_ptr, sched_id);
+}
+
+template <class ActorT>
+ActorOwn<ActorT> register_actor(Slice name, unique_ptr<ActorT> actor_ptr, int32 sched_id) {
+  return Scheduler::instance()->register_actor<ActorT>(name, std::move(actor_ptr), sched_id);
+}
+
+template <class ActorT>
+ActorOwn<ActorT> register_existing_actor(unique_ptr<ActorT> actor_ptr) {
+  return Scheduler::instance()->register_existing_actor(std::move(actor_ptr));
+}
+
+inline void yield_scheduler() {
+  Scheduler::instance()->yield();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl2/ActorLocker.h b/libs/tdlib/td/tdactor/td/actor/impl2/ActorLocker.h
new file mode 100644
index 0000000000..2cb5cb2127
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl2/ActorLocker.h
@@ -0,0 +1,117 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/impl2/ActorSignals.h"
+#include "td/actor/impl2/ActorState.h"
+
+#include "td/utils/logging.h"
+
+#include <atomic>
+
+namespace td {
+namespace actor2 {
+class ActorLocker {
+ public:
+  struct Options {
+    Options() {
+    }
+    bool can_execute_paused = false;
+    bool is_shared = true;
+    Options &with_can_execute_paused(bool new_can_execute_paused) {
+      can_execute_paused = new_can_execute_paused;
+      return *this;
+    }
+    Options &with_is_shared(bool new_is_shared) {
+      is_shared = new_is_shared;
+      return *this;
+    }
+  };
+  explicit ActorLocker(ActorState *state, Options options = {})
+      : state_(state), flags_(state->get_flags_unsafe()), new_flags_{}, options_{options} {
+  }
+  bool try_lock() {
+    CHECK(!own_lock());
+    while (!can_try_add_signals()) {
+      new_flags_ = flags_;
+      new_flags_.set_locked(true);
+      new_flags_.clear_signals();
+      if (state_->state_.compare_exchange_strong(flags_.raw_ref(), new_flags_.raw(), std::memory_order_acq_rel)) {
+        own_lock_ = true;
+        return true;
+      }
+    }
+    return false;
+  }
+  bool try_unlock(ActorState::Flags flags) {
+    CHECK(!flags.is_locked());
+    CHECK(own_lock());
+    // can't unlock with signals set
+    //CHECK(!flags.has_signals());
+
+    flags_ = flags;
+    //try unlock
+    if (state_->state_.compare_exchange_strong(new_flags_.raw_ref(), flags.raw(), std::memory_order_acq_rel)) {
+      own_lock_ = false;
+      return true;
+    }
+
+    // read all signals
+    flags.set_locked(true);
+    flags.clear_signals();
+    do {
+      flags_.add_signals(new_flags_.get_signals());
+    } while (!state_->state_.compare_exchange_strong(new_flags_.raw_ref(), flags.raw(), std::memory_order_acq_rel));
+    new_flags_ = flags;
+    return false;
+  }
+
+  bool try_add_signals(ActorSignals signals) {
+    CHECK(!own_lock());
+    CHECK(can_try_add_signals());
+    new_flags_ = flags_;
+    new_flags_.add_signals(signals);
+    return state_->state_.compare_exchange_strong(flags_.raw_ref(), new_flags_.raw(), std::memory_order_acq_rel);
+  }
+  bool add_signals(ActorSignals signals) {
+    CHECK(!own_lock());
+    while (true) {
+      if (can_try_add_signals()) {
+        if (try_add_signals(signals)) {
+          return false;
+        }
+      } else {
+        if (try_lock()) {
+          flags_.add_signals(signals);
+          return true;
+        }
+      }
+    }
+  }
+  bool own_lock() const {
+    return own_lock_;
+  }
+  ActorState::Flags flags() const {
+    return flags_;
+  }
+  bool can_execute() const {
+    return flags_.is_shared() == options_.is_shared && (options_.can_execute_paused || !flags_.is_pause());
+  }
+
+ private:
+  ActorState *state_{nullptr};
+  ActorState::Flags flags_;
+  ActorState::Flags new_flags_;
+  bool own_lock_{false};
+  Options options_;
+
+  bool can_try_add_signals() const {
+    return flags_.is_locked() || (flags_.is_in_queue() && !can_execute());
+  }
+};
+}  // namespace actor2
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl2/ActorSignals.h b/libs/tdlib/td/tdactor/td/actor/impl2/ActorSignals.h
new file mode 100644
index 0000000000..b7a7483022
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl2/ActorSignals.h
@@ -0,0 +1,84 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+namespace td {
+namespace actor2 {
+class ActorSignals {
+ public:
+  ActorSignals() = default;
+  uint32 raw() const {
+    return raw_;
+  }
+  bool empty() const {
+    return raw_ == 0;
+  }
+  bool has_signal(uint32 signal) const {
+    return (raw_ & (1u << signal)) != 0;
+  }
+  void add_signal(uint32 signal) {
+    raw_ |= (1u << signal);
+  }
+  void add_signals(ActorSignals signals) {
+    raw_ |= signals.raw();
+  }
+  void clear_signal(uint32 signal) {
+    raw_ &= ~(1u << signal);
+  }
+  uint32 first_signal() {
+    if (!raw_) {
+      return 0;
+    }
+#if TD_MSVC
+    int res = 0;
+    int bit = 1;
+    while ((raw_ & bit) == 0) {
+      res++;
+      bit <<= 1;
+    }
+    return res;
+#else
+    return __builtin_ctz(raw_);
+#endif
+  }
+  enum Signal : uint32 {
+    // Signals in order of priority
+    Wakeup = 1,
+    Alarm = 2,
+    Kill = 3,  // immediate kill
+    Io = 4,    // move to io thread
+    Cpu = 5,   // move to cpu thread
+    StartUp = 6,
+    TearDown = 7,
+    // Two signals for mpmc queue logic
+    //
+    // PopSignal is set after actor is popped from queue
+    // When processed it should set InQueue and Pause flags to false.
+    //
+    // MessagesSignal is set after new messages was added to actor
+    // If owner of actor wish to delay message handling, she should set InQueue flag to true and
+    // add actor into mpmc queue.
+    Pop = 8,      // got popped from queue
+    Message = 9,  // got new message
+  };
+
+  static ActorSignals one(uint32 signal) {
+    ActorSignals res;
+    res.add_signal(signal);
+    return res;
+  }
+
+ private:
+  uint32 raw_{0};
+  friend class ActorState;
+  explicit ActorSignals(uint32 raw) : raw_(raw) {
+  }
+};
+}  // namespace actor2
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl2/ActorState.h b/libs/tdlib/td/tdactor/td/actor/impl2/ActorState.h
new file mode 100644
index 0000000000..02ead6bcf6
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl2/ActorState.h
@@ -0,0 +1,166 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/impl2/ActorSignals.h"
+#include "td/actor/impl2/SchedulerId.h"
+
+#include "td/utils/common.h"
+
+#include <atomic>
+
+namespace td {
+namespace actor2 {
+class ActorState {
+ public:
+  class Flags {
+   public:
+    Flags() = default;
+    uint32 raw() const {
+      return raw_;
+    }
+    uint32 &raw_ref() {
+      return raw_;
+    }
+    SchedulerId get_scheduler_id() const {
+      return SchedulerId{static_cast<uint8>(raw_ & SchedulerMask)};
+    }
+    void set_scheduler_id(SchedulerId id) {
+      raw_ = (raw_ & ~SchedulerMask) | id.value();
+    }
+
+    bool is_shared() const {
+      return check_flag(SharedFlag);
+    }
+    void set_shared(bool shared) {
+      set_flag(SharedFlag, shared);
+    }
+
+    bool is_locked() const {
+      return check_flag(LockFlag);
+    }
+    void set_locked(bool locked) {
+      set_flag(LockFlag, locked);
+    }
+
+    bool is_migrate() const {
+      return check_flag(MigrateFlag);
+    }
+    void set_migrate(bool migrate) {
+      set_flag(MigrateFlag, migrate);
+    }
+
+    bool is_pause() const {
+      return check_flag(PauseFlag);
+    }
+    void set_pause(bool pause) {
+      set_flag(PauseFlag, pause);
+    }
+
+    bool is_closed() const {
+      return check_flag(ClosedFlag);
+    }
+    void set_closed(bool closed) {
+      set_flag(ClosedFlag, closed);
+    }
+
+    bool is_in_queue() const {
+      return check_flag(InQueueFlag);
+    }
+    void set_in_queue(bool in_queue) {
+      set_flag(InQueueFlag, in_queue);
+    }
+
+    bool has_signals() const {
+      return check_flag(SignalMask);
+    }
+    void clear_signals() {
+      set_flag(SignalMask, false);
+    }
+    void set_signals(ActorSignals signals) {
+      raw_ = (raw_ & ~SignalMask) | (signals.raw() << SignalOffset);
+    }
+    void add_signals(ActorSignals signals) {
+      raw_ = raw_ | (signals.raw() << SignalOffset);
+    }
+    ActorSignals get_signals() const {
+      return ActorSignals{(raw_ & SignalMask) >> SignalOffset};
+    }
+
+   private:
+    uint32 raw_{0};
+
+    friend class ActorState;
+    Flags(uint32 raw) : raw_(raw) {
+    }
+
+    bool check_flag(uint32 mask) const {
+      return (raw_ & mask) != 0;
+    }
+    void set_flag(uint32 mask, bool flag) {
+      raw_ = (raw_ & ~mask) | (flag * mask);
+    }
+  };
+
+  Flags get_flags_unsafe() {
+    return Flags(state_.load(std::memory_order_relaxed));
+  }
+  void set_flags_unsafe(Flags flags) {
+    state_.store(flags.raw(), std::memory_order_relaxed);
+  }
+
+ private:
+  friend class ActorLocker;
+  std::atomic<uint32> state_{0};
+  enum : uint32 {
+    SchedulerMask = 255,
+
+    // Actors can be shared or not.
+    // If actor is shared, than any thread may try to lock it
+    // If actor is not shared, than it is owned by its scheduler, and only
+    // its scheduler is allowed to access it
+    // This flag may NOT change during the lifetime of an actor
+    SharedFlag = 1 << 9,
+
+    // Only shared actors need lock
+    // Lock if somebody is going to unlock it eventually.
+    // For example actor is locked, when some scheduler is executing its mailbox
+    // Or it is locked when it is in Mpmc queue, so someone will pop it eventually.
+    LockFlag = 1 << 10,
+
+    // While actor is migrating from one scheduler to another no one is allowed to change it
+    // Could not be set for shared actors.
+    MigrateFlag = 1 << 11,
+
+    // While set all messages are delayed
+    // Dropped from flush_maibox
+    // PauseFlag => InQueueFlag
+    PauseFlag = 1 << 12,
+
+    ClosedFlag = 1 << 13,
+
+    InQueueFlag = 1 << 14,
+
+    // Signals
+    SignalOffset = 15,
+    Signal = 1 << SignalOffset,
+    WakeupSignalFlag = Signal << ActorSignals::Wakeup,
+    AlarmSignalFlag = Signal << ActorSignals::Alarm,
+    KillSignalFlag = Signal << ActorSignals::Kill,  // immediate kill
+    IoSignalFlag = Signal << ActorSignals::Io,      // move to io thread
+    CpuSignalFlag = Signal << ActorSignals::Cpu,    // move to cpu thread
+    StartUpSignalFlag = Signal << ActorSignals::StartUp,
+    TearDownSignalFlag = Signal << ActorSignals::TearDown,
+    MessageSignalFlag = Signal << ActorSignals::Message,
+    PopSignalFlag = Signal << ActorSignals::Pop,
+
+    SignalMask = WakeupSignalFlag | AlarmSignalFlag | KillSignalFlag | IoSignalFlag | CpuSignalFlag |
+                 StartUpSignalFlag | TearDownSignalFlag | MessageSignalFlag | PopSignalFlag
+  };
+};
+}  // namespace actor2
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl2/Scheduler.cpp b/libs/tdlib/td/tdactor/td/actor/impl2/Scheduler.cpp
new file mode 100644
index 0000000000..720bf6bc4f
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl2/Scheduler.cpp
@@ -0,0 +1,11 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/actor/impl2/Scheduler.h"
+
+namespace td {
+namespace actor2 {}
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl2/Scheduler.h b/libs/tdlib/td/tdactor/td/actor/impl2/Scheduler.h
new file mode 100644
index 0000000000..9d5783b165
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl2/Scheduler.h
@@ -0,0 +1,1508 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/impl2/ActorLocker.h"
+#include "td/actor/impl2/SchedulerId.h"
+
+#include "td/utils/Closure.h"
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/Heap.h"
+#include "td/utils/List.h"
+#include "td/utils/logging.h"
+#include "td/utils/MpmcQueue.h"
+#include "td/utils/MpmcWaiter.h"
+#include "td/utils/MpscLinkQueue.h"
+#include "td/utils/MpscPollableQueue.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/Poll.h"
+#include "td/utils/port/thread.h"
+#include "td/utils/port/thread_local.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/SharedObjectPool.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Time.h"
+#include "td/utils/type_traits.h"
+
+#include <atomic>
+#include <condition_variable>
+#include <limits>
+#include <memory>
+#include <mutex>
+#include <type_traits>
+#include <utility>
+
+namespace td {
+namespace actor2 {
+class Actor;
+
+template <class Impl>
+class Context {
+ public:
+  static Impl *get() {
+    return context_;
+  }
+  class Guard {
+   public:
+    explicit Guard(Impl *new_context) {
+      old_context_ = context_;
+      context_ = new_context;
+    }
+    ~Guard() {
+      context_ = old_context_;
+    }
+    Guard(const Guard &) = delete;
+    Guard &operator=(const Guard &) = delete;
+    Guard(Guard &&) = delete;
+    Guard &operator=(Guard &&) = delete;
+
+   private:
+    Impl *old_context_;
+  };
+
+ private:
+  static TD_THREAD_LOCAL Impl *context_;
+};
+
+template <class Impl>
+TD_THREAD_LOCAL Impl *Context<Impl>::context_;
+
+enum : uint64 { EmptyLinkToken = std::numeric_limits<uint64>::max() };
+
+class ActorExecuteContext : public Context<ActorExecuteContext> {
+ public:
+  explicit ActorExecuteContext(Actor *actor, Timestamp alarm_timestamp = Timestamp::never())
+      : actor_(actor), alarm_timestamp_(alarm_timestamp) {
+  }
+  Actor &actor() const {
+    CHECK(actor_);
+    return *actor_;
+  }
+  bool has_flags() const {
+    return flags_ != 0;
+  }
+  void set_stop() {
+    flags_ |= 1 << Stop;
+  }
+  bool get_stop() const {
+    return (flags_ & (1 << Stop)) != 0;
+  }
+  void set_pause() {
+    flags_ |= 1 << Pause;
+  }
+  bool get_pause() const {
+    return (flags_ & (1 << Pause)) != 0;
+  }
+  void clear_actor() {
+    actor_ = nullptr;
+  }
+  void set_link_token(uint64 link_token) {
+    link_token_ = link_token;
+  }
+  uint64 get_link_token() const {
+    return link_token_;
+  }
+  Timestamp &alarm_timestamp() {
+    flags_ |= 1 << Alarm;
+    return alarm_timestamp_;
+  }
+  bool get_alarm_flag() const {
+    return (flags_ & (1 << Alarm)) != 0;
+  }
+  Timestamp get_alarm_timestamp() const {
+    return alarm_timestamp_;
+  }
+
+ private:
+  Actor *actor_;
+  uint32 flags_{0};
+  uint64 link_token_{EmptyLinkToken};
+  Timestamp alarm_timestamp_;
+  enum { Stop, Pause, Alarm };
+};
+
+class ActorMessageImpl : private MpscLinkQueueImpl::Node {
+ public:
+  ActorMessageImpl() = default;
+  ActorMessageImpl(const ActorMessageImpl &) = delete;
+  ActorMessageImpl &operator=(const ActorMessageImpl &) = delete;
+  ActorMessageImpl(ActorMessageImpl &&other) = delete;
+  ActorMessageImpl &operator=(ActorMessageImpl &&other) = delete;
+  virtual ~ActorMessageImpl() = default;
+  virtual void run() = 0;
+  //virtual void run_anonymous() = 0;
+
+  // ActorMessage <--> MpscLintQueue::Node
+  // Each actor's mailbox will be a queue
+  static ActorMessageImpl *from_mpsc_link_queue_node(MpscLinkQueueImpl::Node *node) {
+    return static_cast<ActorMessageImpl *>(node);
+  }
+  MpscLinkQueueImpl::Node *to_mpsc_link_queue_node() {
+    return static_cast<MpscLinkQueueImpl::Node *>(this);
+  }
+
+  uint64 link_token_{EmptyLinkToken};
+  bool is_big_{false};
+};
+
+class ActorMessage {
+ public:
+  ActorMessage() = default;
+  explicit ActorMessage(std::unique_ptr<ActorMessageImpl> impl) : impl_(std::move(impl)) {
+  }
+  void run() {
+    CHECK(impl_);
+    impl_->run();
+  }
+  explicit operator bool() {
+    return bool(impl_);
+  }
+  friend class ActorMailbox;
+
+  void set_link_token(uint64 link_token) {
+    impl_->link_token_ = link_token;
+  }
+  uint64 get_link_token() const {
+    return impl_->link_token_;
+  }
+  bool is_big() const {
+    return impl_->is_big_;
+  }
+  void set_big() {
+    impl_->is_big_ = true;
+  }
+
+ private:
+  std::unique_ptr<ActorMessageImpl> impl_;
+
+  template <class T>
+  friend class td::MpscLinkQueue;
+
+  static ActorMessage from_mpsc_link_queue_node(MpscLinkQueueImpl::Node *node) {
+    return ActorMessage(std::unique_ptr<ActorMessageImpl>(ActorMessageImpl::from_mpsc_link_queue_node(node)));
+  }
+  MpscLinkQueueImpl::Node *to_mpsc_link_queue_node() {
+    return impl_.release()->to_mpsc_link_queue_node();
+  }
+};
+
+class ActorMailbox {
+ public:
+  ActorMailbox() = default;
+  ActorMailbox(const ActorMailbox &) = delete;
+  ActorMailbox &operator=(const ActorMailbox &) = delete;
+  ActorMailbox(ActorMailbox &&other) = delete;
+  ActorMailbox &operator=(ActorMailbox &&other) = delete;
+  ~ActorMailbox() {
+    pop_all();
+    while (reader_.read()) {
+      // skip
+    }
+  }
+  class Reader;
+  void push(ActorMessage message) {
+    queue_.push(std::move(message));
+  }
+  void push_unsafe(ActorMessage message) {
+    queue_.push_unsafe(std::move(message));
+  }
+
+  td::MpscLinkQueue<ActorMessage>::Reader &reader() {
+    return reader_;
+  }
+
+  void pop_all() {
+    queue_.pop_all(reader_);
+  }
+  void pop_all_unsafe() {
+    queue_.pop_all_unsafe(reader_);
+  }
+
+ private:
+  td::MpscLinkQueue<ActorMessage> queue_;
+  td::MpscLinkQueue<ActorMessage>::Reader reader_;
+};
+
+class ActorInfo
+    : private HeapNode
+    , private ListNode {
+ public:
+  ActorInfo(std::unique_ptr<Actor> actor, ActorState::Flags state_flags, Slice name)
+      : actor_(std::move(actor)), name_(name.begin(), name.size()) {
+    state_.set_flags_unsafe(state_flags);
+  }
+
+  bool has_actor() const {
+    return bool(actor_);
+  }
+  Actor &actor() {
+    CHECK(has_actor());
+    return *actor_;
+  }
+  Actor *actor_ptr() const {
+    return actor_.get();
+  }
+  void destroy_actor() {
+    actor_.reset();
+  }
+  ActorState &state() {
+    return state_;
+  }
+  ActorMailbox &mailbox() {
+    return mailbox_;
+  }
+  CSlice get_name() const {
+    return name_;
+  }
+
+  HeapNode *as_heap_node() {
+    return this;
+  }
+  static ActorInfo *from_heap_node(HeapNode *node) {
+    return static_cast<ActorInfo *>(node);
+  }
+
+  Timestamp &alarm_timestamp() {
+    return alarm_timestamp_;
+  }
+
+ private:
+  std::unique_ptr<Actor> actor_;
+  ActorState state_;
+  ActorMailbox mailbox_;
+  std::string name_;
+  Timestamp alarm_timestamp_;
+};
+
+using ActorInfoPtr = SharedObjectPool<ActorInfo>::Ptr;
+
+class Actor {
+ public:
+  Actor() = default;
+  Actor(const Actor &) = delete;
+  Actor &operator=(const Actor &) = delete;
+  Actor(Actor &&other) = delete;
+  Actor &operator=(Actor &&other) = delete;
+  virtual ~Actor() = default;
+
+  void set_actor_info_ptr(ActorInfoPtr actor_info_ptr) {
+    actor_info_ptr_ = std::move(actor_info_ptr);
+  }
+  ActorInfoPtr get_actor_info_ptr() {
+    return actor_info_ptr_;
+  }
+
+ protected:
+  // Signal handlers
+  virtual void start_up();   // StartUp signal handler
+  virtual void tear_down();  // TearDown signal handler (or Kill)
+  virtual void hang_up();    // HangUp signal handler
+  virtual void wake_up();    // WakeUp signal handler
+  virtual void alarm();      // Alarm signal handler
+
+  friend class ActorMessageHangup;
+
+  // Event handlers
+  //virtual void hangup_shared();
+  // TODO: raw event?
+
+  virtual void loop();  // default handler
+
+  // Useful functions
+  void yield();  // send wakeup signal to itself
+  void stop();   // send Kill signal to itself
+  Timestamp &alarm_timestamp() {
+    return ActorExecuteContext::get()->alarm_timestamp();
+  }
+  Timestamp get_alarm_timestamp() {
+    return ActorExecuteContext::get()->get_alarm_timestamp();
+  }
+
+  CSlice get_name() {
+    return actor_info_ptr_->get_name();
+  }
+
+  // Inteface to scheduler
+  // Query will be just passed to current scheduler
+  // Timeout functions
+  //bool has_timeout() const;
+  //void set_timeout_in(double timeout_in);
+  //void set_timeout_at(double timeout_at);
+  //void cancel_timeout();
+  //uint64 get_link_token();  // get current request's link_token
+  //set context that will be inherited by all childrens
+  //void set_context(std::shared_ptr<ActorContext> context);
+
+  //ActorShared<> actor_shared();  // ActorShared to itself
+  //template <class SelfT>
+  //ActorShared<SelfT> actor_shared(SelfT *self, uint64 id = static_cast<uint64>(-1));  // ActorShared with type
+
+  // Create EventFull to itself
+  //template <class FuncT, class... ArgsT>
+  //auto self_closure(FuncT &&func, ArgsT &&... args);
+  //template <class SelfT, class FuncT, class... ArgsT>
+  //auto self_closure(SelfT *self, FuncT &&func, ArgsT &&... args);
+  //template <class LambdaT>
+  //auto self_lambda(LambdaT &&lambda);
+
+  //void do_stop();  // process Kill signal immediately
+
+ private:
+  friend class ActorExecutor;
+  ActorInfoPtr actor_info_ptr_;
+};
+// Signal handlers
+inline void Actor::start_up() {
+  yield();
+}
+inline void Actor::tear_down() {
+  // noop
+}
+inline void Actor::hang_up() {
+  stop();
+}
+inline void Actor::wake_up() {
+  loop();
+}
+inline void Actor::alarm() {
+  loop();
+}
+
+inline void Actor::loop() {
+  // noop
+}
+
+// Useful functions
+inline void Actor::yield() {
+  // TODO
+}
+inline void Actor::stop() {
+  ActorExecuteContext::get()->set_stop();
+}
+
+class ActorInfoCreator {
+ public:
+  class Options {
+   public:
+    Options() = default;
+
+    Options &with_name(Slice new_name) {
+      name = new_name;
+      return *this;
+    }
+
+    Options &on_scheduler(SchedulerId new_scheduler_id) {
+      scheduler_id = new_scheduler_id;
+      return *this;
+    }
+    bool has_scheduler() const {
+      return scheduler_id.is_valid();
+    }
+    Options &with_poll() {
+      is_shared = false;
+      return *this;
+    }
+
+   private:
+    friend class ActorInfoCreator;
+    Slice name;
+    SchedulerId scheduler_id;
+    bool is_shared{true};
+    bool in_queue{true};
+    //TODO: rename
+  };
+
+  //Create unlocked actor. One must send StartUp signal immediately.
+  ActorInfoPtr create(std::unique_ptr<Actor> actor, const Options &args) {
+    ActorState::Flags flags;
+    flags.set_scheduler_id(args.scheduler_id);
+    flags.set_shared(args.is_shared);
+    flags.set_in_queue(args.in_queue);
+    flags.set_signals(ActorSignals::one(ActorSignals::StartUp));
+
+    auto actor_info_ptr = pool_.alloc(std::move(actor), flags, args.name);
+    actor_info_ptr->actor().set_actor_info_ptr(actor_info_ptr);
+    return actor_info_ptr;
+  }
+
+  ActorInfoCreator() = default;
+  ActorInfoCreator(const ActorInfoCreator &) = delete;
+  ActorInfoCreator &operator=(const ActorInfoCreator &) = delete;
+  ActorInfoCreator(ActorInfoCreator &&other) = delete;
+  ActorInfoCreator &operator=(ActorInfoCreator &&other) = delete;
+  ~ActorInfoCreator() {
+    pool_.for_each([](auto &actor_info) { actor_info.destroy_actor(); });
+  }
+
+ private:
+  SharedObjectPool<ActorInfo> pool_;
+};
+
+using ActorOptions = ActorInfoCreator::Options;
+
+class SchedulerDispatcher {
+ public:
+  virtual SchedulerId get_scheduler_id() const = 0;
+  virtual void add_to_queue(ActorInfoPtr actor_info_ptr, SchedulerId scheduler_id, bool need_poll) = 0;
+  virtual void set_alarm_timestamp(const ActorInfoPtr &actor_info_ptr, Timestamp timestamp) = 0;
+
+  SchedulerDispatcher() = default;
+  SchedulerDispatcher(const SchedulerDispatcher &) = delete;
+  SchedulerDispatcher &operator=(const SchedulerDispatcher &) = delete;
+  SchedulerDispatcher(SchedulerDispatcher &&other) = delete;
+  SchedulerDispatcher &operator=(SchedulerDispatcher &&other) = delete;
+  virtual ~SchedulerDispatcher() = default;
+};
+
+class ActorExecutor {
+ public:
+  struct Options {
+    Options &with_from_queue() {
+      from_queue = true;
+      return *this;
+    }
+    Options &with_has_poll(bool new_has_poll) {
+      this->has_poll = new_has_poll;
+      return *this;
+    }
+    bool from_queue{false};
+    bool has_poll{false};
+  };
+  ActorExecutor(ActorInfo &actor_info, SchedulerDispatcher &dispatcher, Options options)
+      : actor_info_(actor_info), dispatcher_(dispatcher), options_(options) {
+    //LOG(ERROR) << "START " << actor_info_.get_name() << " " << tag("from_queue", from_queue);
+    start();
+  }
+  ActorExecutor(const ActorExecutor &) = delete;
+  ActorExecutor &operator=(const ActorExecutor &) = delete;
+  ActorExecutor(ActorExecutor &&other) = delete;
+  ActorExecutor &operator=(ActorExecutor &&other) = delete;
+  ~ActorExecutor() {
+    //LOG(ERROR) << "FINISH " << actor_info_.get_name() << " " << tag("own_lock", actor_locker_.own_lock());
+    finish();
+  }
+
+  // our best guess if actor is closed or not
+  bool can_send() {
+    return !flags().is_closed();
+  }
+
+  bool can_send_immediate() {
+    return actor_locker_.own_lock() && !actor_execute_context_.has_flags() && actor_locker_.can_execute();
+  }
+
+  template <class F>
+  void send_immediate(F &&f, uint64 link_token) {
+    CHECK(can_send_immediate());
+    if (!can_send()) {
+      return;
+    }
+    actor_execute_context_.set_link_token(link_token);
+    f();
+  }
+  void send_immediate(ActorMessage message) {
+    CHECK(can_send_immediate());
+    if (message.is_big()) {
+      actor_info_.mailbox().reader().delay(std::move(message));
+      pending_signals_.add_signal(ActorSignals::Message);
+      actor_execute_context_.set_pause();
+      return;
+    }
+    actor_execute_context_.set_link_token(message.get_link_token());
+    message.run();
+  }
+  void send_immediate(ActorSignals signals) {
+    CHECK(can_send_immediate());
+    while (flush_one_signal(signals) && can_send_immediate()) {
+    }
+    pending_signals_.add_signals(signals);
+  }
+
+  void send(ActorMessage message) {
+    if (!can_send()) {
+      return;
+    }
+    if (can_send_immediate()) {
+      return send_immediate(std::move(message));
+    }
+    actor_info_.mailbox().push(std::move(message));
+    pending_signals_.add_signal(ActorSignals::Message);
+  }
+
+  void send(ActorSignals signals) {
+    if (!can_send()) {
+      return;
+    }
+
+    pending_signals_.add_signals(signals);
+  }
+
+ private:
+  ActorInfo &actor_info_;
+  SchedulerDispatcher &dispatcher_;
+  Options options_;
+  ActorLocker actor_locker_{
+      &actor_info_.state(),
+      ActorLocker::Options().with_can_execute_paused(options_.from_queue).with_is_shared(!options_.has_poll)};
+
+  ActorExecuteContext actor_execute_context_{actor_info_.actor_ptr(), actor_info_.alarm_timestamp()};
+  ActorExecuteContext::Guard guard{&actor_execute_context_};
+
+  ActorState::Flags flags_;
+  ActorSignals pending_signals_;
+
+  ActorState::Flags &flags() {
+    return flags_;
+  }
+
+  void start() {
+    if (!can_send()) {
+      return;
+    }
+
+    ActorSignals signals;
+    SCOPE_EXIT {
+      pending_signals_.add_signals(signals);
+    };
+
+    if (options_.from_queue) {
+      signals.add_signal(ActorSignals::Pop);
+    }
+
+    actor_locker_.try_lock();
+    flags_ = actor_locker_.flags();
+
+    if (!actor_locker_.own_lock()) {
+      return;
+    }
+
+    if (options_.from_queue) {
+      flags().set_pause(false);
+    }
+    if (!actor_locker_.can_execute()) {
+      CHECK(!options_.from_queue);
+      return;
+    }
+
+    signals.add_signals(flags().get_signals());
+    actor_info_.mailbox().pop_all();
+
+    while (!actor_execute_context_.has_flags() && flush_one(signals)) {
+    }
+  }
+
+  void finish() {
+    if (!actor_locker_.own_lock()) {
+      if (!pending_signals_.empty() && actor_locker_.add_signals(pending_signals_)) {
+        flags_ = actor_locker_.flags();
+      } else {
+        return;
+      }
+    }
+    CHECK(actor_locker_.own_lock());
+
+    if (actor_execute_context_.has_flags()) {
+      if (actor_execute_context_.get_stop()) {
+        if (actor_info_.alarm_timestamp()) {
+          dispatcher_.set_alarm_timestamp(actor_info_.actor().get_actor_info_ptr(), Timestamp::never());
+        }
+        flags_.set_closed(true);
+        actor_info_.actor().tear_down();
+        actor_info_.destroy_actor();
+        return;
+      }
+      if (actor_execute_context_.get_pause()) {
+        flags_.set_pause(true);
+      }
+      if (actor_execute_context_.get_alarm_flag()) {
+        auto old_timestamp = actor_info_.alarm_timestamp();
+        auto new_timestamp = actor_execute_context_.get_alarm_timestamp();
+        if (!(old_timestamp == new_timestamp)) {
+          actor_info_.alarm_timestamp() = new_timestamp;
+          dispatcher_.set_alarm_timestamp(actor_info_.actor().get_actor_info_ptr(), new_timestamp);
+        }
+      }
+    }
+    flags_.set_signals(pending_signals_);
+
+    bool add_to_queue = false;
+    while (true) {
+      // Drop InQueue flag if has pop signal
+      // Can't delay this signal
+      auto signals = flags().get_signals();
+      if (signals.has_signal(ActorSignals::Pop)) {
+        signals.clear_signal(ActorSignals::Pop);
+        flags().set_signals(signals);
+        flags().set_in_queue(false);
+      }
+
+      if (flags().has_signals() && !flags().is_in_queue()) {
+        add_to_queue = true;
+        flags().set_in_queue(true);
+      }
+      if (actor_locker_.try_unlock(flags())) {
+        if (add_to_queue) {
+          dispatcher_.add_to_queue(actor_info_.actor().get_actor_info_ptr(), flags().get_scheduler_id(),
+                                   !flags().is_shared());
+        }
+        break;
+      }
+      flags_ = actor_locker_.flags();
+    }
+  }
+
+  bool flush_one(ActorSignals &signals) {
+    return flush_one_signal(signals) || flush_one_message();
+  }
+
+  bool flush_one_signal(ActorSignals &signals) {
+    auto signal = signals.first_signal();
+    if (!signal) {
+      return false;
+    }
+    switch (signal) {
+      case ActorSignals::Wakeup:
+        actor_info_.actor().wake_up();
+        break;
+      case ActorSignals::Alarm:
+        if (actor_execute_context_.get_alarm_timestamp().is_in_past()) {
+          actor_execute_context_.alarm_timestamp() = Timestamp::never();
+          actor_info_.actor().alarm();
+        }
+        break;
+      case ActorSignals::Kill:
+        actor_execute_context_.set_stop();
+        break;
+      case ActorSignals::StartUp:
+        actor_info_.actor().start_up();
+        break;
+      case ActorSignals::TearDown:
+        actor_info_.actor().tear_down();
+        break;
+      case ActorSignals::Pop:
+        flags().set_in_queue(false);
+        break;
+
+      case ActorSignals::Message:
+        break;
+      case ActorSignals::Io:
+      case ActorSignals::Cpu:
+        LOG(FATAL) << "TODO";
+      default:
+        UNREACHABLE();
+    }
+    signals.clear_signal(signal);
+    return true;
+  }
+
+  bool flush_one_message() {
+    auto message = actor_info_.mailbox().reader().read();
+    if (!message) {
+      return false;
+    }
+    if (message.is_big() && !options_.from_queue) {
+      actor_info_.mailbox().reader().delay(std::move(message));
+      pending_signals_.add_signal(ActorSignals::Message);
+      actor_execute_context_.set_pause();
+      return false;
+    }
+
+    actor_execute_context_.set_link_token(message.get_link_token());
+    message.run();
+    return true;
+  }
+};
+
+using SchedulerMessage = ActorInfoPtr;
+
+struct WorkerInfo {
+  enum class Type { Io, Cpu } type{Type::Io};
+  WorkerInfo() = default;
+  explicit WorkerInfo(Type type) : type(type) {
+  }
+  ActorInfoCreator actor_info_creator;
+};
+
+struct SchedulerInfo {
+  SchedulerId id;
+  // will be read by all workers is any thread
+  std::unique_ptr<MpmcQueue<SchedulerMessage>> cpu_queue;
+  std::unique_ptr<MpmcWaiter> cpu_queue_waiter;
+  // only scheduler itself may read from io_queue_
+  std::unique_ptr<MpscPollableQueue<SchedulerMessage>> io_queue;
+  size_t cpu_threads_count{0};
+
+  std::unique_ptr<WorkerInfo> io_worker;
+  std::vector<std::unique_ptr<WorkerInfo>> cpu_workers;
+};
+
+struct SchedulerGroupInfo {
+  explicit SchedulerGroupInfo(size_t n) : schedulers(n) {
+  }
+  std::atomic<bool> is_stop_requested{false};
+
+  int active_scheduler_count{0};
+  std::mutex active_scheduler_count_mutex;
+  std::condition_variable active_scheduler_count_condition_variable;
+
+  std::vector<SchedulerInfo> schedulers;
+};
+
+class SchedulerContext
+    : public Context<SchedulerContext>
+    , public SchedulerDispatcher {
+ public:
+  // DispatcherInterface
+  SchedulerDispatcher &dispatcher() {
+    return *this;
+  }
+
+  // ActorCreator Interface
+  virtual ActorInfoCreator &get_actor_info_creator() = 0;
+
+  // Poll interface
+  virtual bool has_poll() = 0;
+  virtual Poll &get_poll() = 0;
+
+  // Timeout interface
+  virtual bool has_heap() = 0;
+  virtual KHeap<double> &get_heap() = 0;
+
+  // Stop all schedulers
+  virtual bool is_stop_requested() = 0;
+  virtual void stop() = 0;
+};
+
+#if !TD_THREAD_UNSUPPORTED
+class Scheduler {
+ public:
+  Scheduler(std::shared_ptr<SchedulerGroupInfo> scheduler_group_info, SchedulerId id, size_t cpu_threads_count)
+      : scheduler_group_info_(std::move(scheduler_group_info)), cpu_threads_(cpu_threads_count) {
+    scheduler_group_info_->active_scheduler_count++;
+    info_ = &scheduler_group_info_->schedulers.at(id.value());
+    info_->id = id;
+    if (cpu_threads_count != 0) {
+      info_->cpu_threads_count = cpu_threads_count;
+      info_->cpu_queue = std::make_unique<MpmcQueue<SchedulerMessage>>(1024, max_thread_count());
+      info_->cpu_queue_waiter = std::make_unique<MpmcWaiter>();
+    }
+    info_->io_queue = std::make_unique<MpscPollableQueue<SchedulerMessage>>();
+    info_->io_queue->init();
+
+    info_->cpu_workers.resize(cpu_threads_count);
+    for (auto &worker : info_->cpu_workers) {
+      worker = std::make_unique<WorkerInfo>(WorkerInfo::Type::Cpu);
+    }
+    info_->io_worker = std::make_unique<WorkerInfo>(WorkerInfo::Type::Io);
+
+    poll_.init();
+    io_worker_ = std::make_unique<IoWorker>(*info_->io_queue);
+  }
+
+  Scheduler(const Scheduler &) = delete;
+  Scheduler &operator=(const Scheduler &) = delete;
+  Scheduler(Scheduler &&other) = delete;
+  Scheduler &operator=(Scheduler &&other) = delete;
+  ~Scheduler() {
+    // should stop
+    stop();
+    do_stop();
+  }
+
+  void start() {
+    for (size_t i = 0; i < cpu_threads_.size(); i++) {
+      cpu_threads_[i] = td::thread([this, i] {
+        this->run_in_context_impl(*this->info_->cpu_workers[i],
+                                  [this] { CpuWorker(*info_->cpu_queue, *info_->cpu_queue_waiter).run(); });
+      });
+    }
+    this->run_in_context([this] { this->io_worker_->start_up(); });
+  }
+
+  template <class F>
+  void run_in_context(F &&f) {
+    run_in_context_impl(*info_->io_worker, std::forward<F>(f));
+  }
+
+  bool run(double timeout) {
+    bool res;
+    run_in_context_impl(*info_->io_worker, [this, timeout, &res] {
+      if (SchedulerContext::get()->is_stop_requested()) {
+        res = false;
+      } else {
+        res = io_worker_->run_once(timeout);
+      }
+      if (!res) {
+        io_worker_->tear_down();
+      }
+    });
+    if (!res) {
+      do_stop();
+    }
+    return res;
+  }
+
+  // Just syntactic sugar
+  void stop() {
+    run_in_context([] { SchedulerContext::get()->stop(); });
+  }
+
+  SchedulerId get_scheduler_id() const {
+    return info_->id;
+  }
+
+ private:
+  std::shared_ptr<SchedulerGroupInfo> scheduler_group_info_;
+  SchedulerInfo *info_;
+  std::vector<td::thread> cpu_threads_;
+  bool is_stopped_{false};
+  Poll poll_;
+  KHeap<double> heap_;
+  class IoWorker;
+  std::unique_ptr<IoWorker> io_worker_;
+
+  class SchedulerContextImpl : public SchedulerContext {
+   public:
+    SchedulerContextImpl(WorkerInfo *worker, SchedulerInfo *scheduler, SchedulerGroupInfo *scheduler_group, Poll *poll,
+                         KHeap<double> *heap)
+        : worker_(worker), scheduler_(scheduler), scheduler_group_(scheduler_group), poll_(poll), heap_(heap) {
+    }
+
+    SchedulerId get_scheduler_id() const override {
+      return scheduler()->id;
+    }
+    void add_to_queue(ActorInfoPtr actor_info_ptr, SchedulerId scheduler_id, bool need_poll) override {
+      if (!scheduler_id.is_valid()) {
+        scheduler_id = scheduler()->id;
+      }
+      auto &info = scheduler_group()->schedulers.at(scheduler_id.value());
+      if (need_poll) {
+        info.io_queue->writer_put(std::move(actor_info_ptr));
+      } else {
+        info.cpu_queue->push(std::move(actor_info_ptr), get_thread_id());
+        info.cpu_queue_waiter->notify();
+      }
+    }
+
+    ActorInfoCreator &get_actor_info_creator() override {
+      return worker()->actor_info_creator;
+    }
+
+    bool has_poll() override {
+      return poll_ != nullptr;
+    }
+    Poll &get_poll() override {
+      CHECK(has_poll());
+      return *poll_;
+    }
+
+    bool has_heap() override {
+      return heap_ != nullptr;
+    }
+    KHeap<double> &get_heap() override {
+      CHECK(has_heap());
+      return *heap_;
+    }
+
+    void set_alarm_timestamp(const ActorInfoPtr &actor_info_ptr, Timestamp timestamp) override {
+      // we are in PollWorker
+      CHECK(has_heap());
+      auto &heap = get_heap();
+      auto *heap_node = actor_info_ptr->as_heap_node();
+      if (timestamp) {
+        if (heap_node->in_heap()) {
+          heap.fix(timestamp.at(), heap_node);
+        } else {
+          heap.insert(timestamp.at(), heap_node);
+        }
+      } else {
+        if (heap_node->in_heap()) {
+          heap.erase(heap_node);
+        }
+      }
+
+      // TODO: do something in plain worker
+    }
+
+    bool is_stop_requested() override {
+      return scheduler_group()->is_stop_requested;
+    }
+
+    void stop() override {
+      bool expect_false = false;
+      // Trying to set close_flag_ to true with CAS
+      auto &group = *scheduler_group();
+      if (!group.is_stop_requested.compare_exchange_strong(expect_false, true)) {
+        return;
+      }
+
+      // Notify all workers of all schedulers
+      for (auto &scheduler_info : group.schedulers) {
+        scheduler_info.io_queue->writer_put({});
+        for (size_t i = 0; i < scheduler_info.cpu_threads_count; i++) {
+          scheduler_info.cpu_queue->push({}, get_thread_id());
+          scheduler_info.cpu_queue_waiter->notify();
+        }
+      }
+    }
+
+   private:
+    WorkerInfo *worker() const {
+      return worker_;
+    }
+    SchedulerInfo *scheduler() const {
+      return scheduler_;
+    }
+    SchedulerGroupInfo *scheduler_group() const {
+      return scheduler_group_;
+    }
+
+    WorkerInfo *worker_;
+    SchedulerInfo *scheduler_;
+    SchedulerGroupInfo *scheduler_group_;
+    Poll *poll_;
+
+    KHeap<double> *heap_;
+  };
+
+  template <class F>
+  void run_in_context_impl(WorkerInfo &worker_info, F &&f) {
+    bool is_io_worker = worker_info.type == WorkerInfo::Type::Io;
+    SchedulerContextImpl context(&worker_info, info_, scheduler_group_info_.get(), is_io_worker ? &poll_ : nullptr,
+                                 is_io_worker ? &heap_ : nullptr);
+    SchedulerContext::Guard guard(&context);
+    f();
+  }
+
+  class CpuWorker {
+   public:
+    CpuWorker(MpmcQueue<SchedulerMessage> &queue, MpmcWaiter &waiter) : queue_(queue), waiter_(waiter) {
+    }
+    void run() {
+      auto thread_id = get_thread_id();
+      auto &dispatcher = SchedulerContext::get()->dispatcher();
+
+      int yields = 0;
+      while (true) {
+        SchedulerMessage message;
+        if (queue_.try_pop(message, thread_id)) {
+          if (!message) {
+            return;
+          }
+          ActorExecutor executor(*message, dispatcher, ActorExecutor::Options().with_from_queue());
+          yields = waiter_.stop_wait(yields, thread_id);
+        } else {
+          yields = waiter_.wait(yields, thread_id);
+        }
+      }
+    }
+
+   private:
+    MpmcQueue<SchedulerMessage> &queue_;
+    MpmcWaiter &waiter_;
+  };
+
+  class IoWorker {
+   public:
+    explicit IoWorker(MpscPollableQueue<SchedulerMessage> &queue) : queue_(queue) {
+    }
+
+    void start_up() {
+      auto &poll = SchedulerContext::get()->get_poll();
+      poll.subscribe(queue_.reader_get_event_fd().get_fd(), Fd::Flag::Read);
+    }
+    void tear_down() {
+      auto &poll = SchedulerContext::get()->get_poll();
+      poll.unsubscribe(queue_.reader_get_event_fd().get_fd());
+    }
+
+    bool run_once(double timeout) {
+      auto &dispatcher = SchedulerContext::get()->dispatcher();
+      auto &poll = SchedulerContext::get()->get_poll();
+      auto &heap = SchedulerContext::get()->get_heap();
+
+      auto now = Time::now();  // update Time::now_cached()
+      while (!heap.empty() && heap.top_key() <= now) {
+        auto *heap_node = heap.pop();
+        auto *actor_info = ActorInfo::from_heap_node(heap_node);
+
+        ActorExecutor executor(*actor_info, dispatcher, ActorExecutor::Options().with_has_poll(true));
+        if (executor.can_send_immediate()) {
+          executor.send_immediate(ActorSignals::one(ActorSignals::Alarm));
+        } else {
+          executor.send(ActorSignals::one(ActorSignals::Alarm));
+        }
+      }
+
+      const int size = queue_.reader_wait_nonblock();
+      for (int i = 0; i < size; i++) {
+        auto message = queue_.reader_get_unsafe();
+        if (!message) {
+          return false;
+        }
+        ActorExecutor executor(*message, dispatcher, ActorExecutor::Options().with_from_queue().with_has_poll(true));
+      }
+      queue_.reader_flush();
+
+      bool can_sleep = size == 0 && timeout != 0;
+      int32 timeout_ms = 0;
+      if (can_sleep) {
+        auto wakeup_timestamp = Timestamp::in(timeout);
+        if (!heap.empty()) {
+          wakeup_timestamp.relax(Timestamp::at(heap.top_key()));
+        }
+        timeout_ms = static_cast<int>(wakeup_timestamp.in() * 1000) + 1;
+        if (timeout_ms < 0) {
+          timeout_ms = 0;
+        }
+        //const int thirty_seconds = 30 * 1000;
+        //if (timeout_ms > thirty_seconds) {
+        //timeout_ms = thirty_seconds;
+        //}
+      }
+      poll.run(timeout_ms);
+      return true;
+    }
+
+   private:
+    MpscPollableQueue<SchedulerMessage> &queue_;
+  };
+
+  void do_stop() {
+    if (is_stopped_) {
+      return;
+    }
+    // wait other threads to finish
+    for (auto &thread : cpu_threads_) {
+      thread.join();
+    }
+    // Can't do anything else, other schedulers may send queries to this one.
+    // Must wait till every scheduler is stopped first..
+    is_stopped_ = true;
+
+    io_worker_.reset();
+    poll_.clear();
+
+    std::unique_lock<std::mutex> lock(scheduler_group_info_->active_scheduler_count_mutex);
+    scheduler_group_info_->active_scheduler_count--;
+    scheduler_group_info_->active_scheduler_count_condition_variable.notify_all();
+  }
+
+ public:
+  static void close_scheduler_group(SchedulerGroupInfo &group_info) {
+    LOG(ERROR) << "close scheduler group";
+    // Cannot close scheduler group before somebody asked to stop them
+    CHECK(group_info.is_stop_requested);
+    {
+      std::unique_lock<std::mutex> lock(group_info.active_scheduler_count_mutex);
+      group_info.active_scheduler_count_condition_variable.wait(lock,
+                                                                [&] { return group_info.active_scheduler_count == 0; });
+    }
+
+    // Drain all queues
+    // Just to destroy all elements should be ok.
+    for (auto &scheduler_info : group_info.schedulers) {
+      // Drain io queue
+      auto &io_queue = *scheduler_info.io_queue;
+      while (true) {
+        int n = io_queue.reader_wait_nonblock();
+        if (n == 0) {
+          break;
+        }
+        while (n-- > 0) {
+          auto message = io_queue.reader_get_unsafe();
+          // message's destructor is called
+        }
+      }
+      scheduler_info.io_queue.reset();
+
+      // Drain cpu queue
+      auto &cpu_queue = *scheduler_info.cpu_queue;
+      while (true) {
+        SchedulerMessage message;
+        if (!cpu_queue.try_pop(message, get_thread_id())) {
+          break;
+        }
+        // message's destructor is called
+      }
+      scheduler_info.cpu_queue.reset();
+
+      // Do not destroy worker infos. run_in_context will crash if they are empty
+    }
+  }
+};
+
+// Actor messages
+template <class LambdaT>
+class ActorMessageLambda : public ActorMessageImpl {
+ public:
+  template <class FromLambdaT>
+  explicit ActorMessageLambda(FromLambdaT &&lambda) : lambda_(std::forward<FromLambdaT>(lambda)) {
+  }
+  void run() override {
+    lambda_();
+  }
+
+ private:
+  LambdaT lambda_;
+};
+
+class ActorMessageHangup : public ActorMessageImpl {
+ public:
+  void run() override {
+    ActorExecuteContext::get()->actor().hang_up();
+  }
+};
+
+class ActorMessageCreator {
+ public:
+  template <class F>
+  static ActorMessage lambda(F &&f) {
+    return ActorMessage(std::make_unique<ActorMessageLambda<F>>(std::forward<F>(f)));
+  }
+
+  static ActorMessage hangup() {
+    return ActorMessage(std::make_unique<ActorMessageHangup>());
+  }
+
+  // Use faster allocation?
+};
+
+// SYNTAX SHUGAR
+namespace detail {
+struct ActorRef {
+  ActorRef(ActorInfo &actor_info, uint64 link_token = EmptyLinkToken) : actor_info(actor_info), link_token(link_token) {
+  }
+
+  ActorInfo &actor_info;
+  uint64 link_token;
+};
+
+template <class T>
+T &current_actor() {
+  return static_cast<T &>(ActorExecuteContext::get()->actor());
+}
+
+void send_message(ActorInfo &actor_info, ActorMessage message) {
+  ActorExecutor executor(actor_info, SchedulerContext::get()->dispatcher(), ActorExecutor::Options());
+  executor.send(std::move(message));
+}
+
+void send_message(ActorRef actor_ref, ActorMessage message) {
+  message.set_link_token(actor_ref.link_token);
+  send_message(actor_ref.actor_info, std::move(message));
+}
+void send_message_later(ActorInfo &actor_info, ActorMessage message) {
+  ActorExecutor executor(actor_info, SchedulerContext::get()->dispatcher(), ActorExecutor::Options());
+  executor.send(std::move(message));
+}
+
+void send_message_later(ActorRef actor_ref, ActorMessage message) {
+  message.set_link_token(actor_ref.link_token);
+  send_message_later(actor_ref.actor_info, std::move(message));
+}
+
+template <class ExecuteF, class ToMessageF>
+void send_immediate(ActorRef actor_ref, ExecuteF &&execute, ToMessageF &&to_message) {
+  auto &scheduler_context = *SchedulerContext::get();
+  ActorExecutor executor(actor_ref.actor_info, scheduler_context.dispatcher(),
+                         ActorExecutor::Options().with_has_poll(scheduler_context.has_poll()));
+  if (executor.can_send_immediate()) {
+    return executor.send_immediate(execute, actor_ref.link_token);
+  }
+  auto message = to_message();
+  message.set_link_token(actor_ref.link_token);
+  executor.send(std::move(message));
+}
+
+template <class F>
+void send_lambda(ActorRef actor_ref, F &&lambda) {
+  send_immediate(actor_ref, lambda, [&lambda]() mutable { return ActorMessageCreator::lambda(std::move(lambda)); });
+}
+template <class F>
+void send_lambda_later(ActorRef actor_ref, F &&lambda) {
+  send_message_later(actor_ref, ActorMessageCreator::lambda(std::move(lambda)));
+}
+
+template <class ClosureT>
+void send_closure_impl(ActorRef actor_ref, ClosureT &&closure) {
+  using ActorType = typename ClosureT::ActorType;
+  send_immediate(actor_ref, [&closure]() mutable { closure.run(&current_actor<ActorType>()); },
+                 [&closure]() mutable {
+                   return ActorMessageCreator::lambda([closure = to_delayed_closure(std::move(closure))]() mutable {
+                     closure.run(&current_actor<ActorType>());
+                   });
+                 });
+}
+
+template <class... ArgsT>
+void send_closure(ActorRef actor_ref, ArgsT &&... args) {
+  send_closure_impl(actor_ref, create_immediate_closure(std::forward<ArgsT>(args)...));
+}
+
+template <class ClosureT>
+void send_closure_later_impl(ActorRef actor_ref, ClosureT &&closure) {
+  using ActorType = typename ClosureT::ActorType;
+  send_message_later(actor_ref, ActorMessageCreator::lambda([closure = std::move(closure)]() mutable {
+                       closure.run(&current_actor<ActorType>());
+                     }));
+}
+
+template <class... ArgsT>
+void send_closure_later(ActorRef actor_ref, ArgsT &&... args) {
+  send_closure_later_impl(actor_ref, create_delayed_closure(std::forward<ArgsT>(args)...));
+}
+
+void register_actor_info_ptr(ActorInfoPtr actor_info_ptr) {
+  auto state = actor_info_ptr->state().get_flags_unsafe();
+  SchedulerContext::get()->add_to_queue(std::move(actor_info_ptr), state.get_scheduler_id(), !state.is_shared());
+}
+
+template <class T, class... ArgsT>
+ActorInfoPtr create_actor(ActorOptions &options, ArgsT &&... args) {
+  auto *scheduler_context = SchedulerContext::get();
+  if (!options.has_scheduler()) {
+    options.on_scheduler(scheduler_context->get_scheduler_id());
+  }
+  auto res =
+      scheduler_context->get_actor_info_creator().create(std::make_unique<T>(std::forward<ArgsT>(args)...), options);
+  register_actor_info_ptr(res);
+  return res;
+}
+}  // namespace detail
+
+// Essentially ActorInfoWeakPtr with Type
+template <class ActorType = Actor>
+class ActorId {
+ public:
+  using ActorT = ActorType;
+  ActorId() = default;
+  ActorId(const ActorId &) = default;
+  ActorId &operator=(const ActorId &) = default;
+  ActorId(ActorId &&other) = default;
+  ActorId &operator=(ActorId &&other) = default;
+
+  // allow only conversion from child to parent
+  template <class ToActorType, class = std::enable_if_t<std::is_base_of<ToActorType, ActorType>::value>>
+  explicit operator ActorId<ToActorType>() const {
+    return ActorId<ToActorType>(ptr_);
+  }
+
+  const ActorInfoPtr &actor_info_ptr() const {
+    return ptr_;
+  }
+
+  ActorInfo &actor_info() const {
+    CHECK(ptr_);
+    return *ptr_;
+  }
+  bool empty() const {
+    return !ptr_;
+  }
+
+  template <class... ArgsT>
+  static ActorId<ActorType> create(ActorOptions &options, ArgsT &&... args) {
+    return ActorId<ActorType>(detail::create_actor<ActorType>(options, std::forward<ArgsT>(args)...));
+  }
+
+  detail::ActorRef as_actor_ref() const {
+    CHECK(!empty());
+    return detail::ActorRef(*actor_info_ptr());
+  }
+
+ private:
+  ActorInfoPtr ptr_;
+
+  explicit ActorId(ActorInfoPtr ptr) : ptr_(std::move(ptr)) {
+  }
+
+  template <class SelfT>
+  friend ActorId<SelfT> actor_id(SelfT *self);
+};
+
+template <class ActorType = Actor>
+class ActorOwn {
+ public:
+  using ActorT = ActorType;
+  ActorOwn() = default;
+  explicit ActorOwn(ActorId<ActorType> id) : id_(std::move(id)) {
+  }
+  template <class OtherActorType>
+  explicit ActorOwn(ActorId<OtherActorType> id) : id_(std::move(id)) {
+  }
+  template <class OtherActorType>
+  explicit ActorOwn(ActorOwn<OtherActorType> &&other) : id_(other.release()) {
+  }
+  template <class OtherActorType>
+  ActorOwn &operator=(ActorOwn<OtherActorType> &&other) {
+    reset(other.release());
+  }
+  ActorOwn(ActorOwn &&other) : id_(other.release()) {
+  }
+  ActorOwn &operator=(ActorOwn &&other) {
+    reset(other.release());
+  }
+  ActorOwn(const ActorOwn &) = delete;
+  ActorOwn &operator=(const ActorOwn &) = delete;
+  ~ActorOwn() {
+    reset();
+  }
+
+  bool empty() const {
+    return id_.empty();
+  }
+  bool is_alive() const {
+    return id_.is_alive();
+  }
+  ActorId<ActorType> get() const {
+    return id_;
+  }
+  ActorId<ActorType> release() {
+    return std::move(id_);
+  }
+  void reset(ActorId<ActorType> other = ActorId<ActorType>()) {
+    static_assert(sizeof(ActorType) > 0, "Can't use ActorOwn with incomplete type");
+    hangup();
+    id_ = std::move(other);
+  }
+  const ActorId<ActorType> *operator->() const {
+    return &id_;
+  }
+
+  detail::ActorRef as_actor_ref() const {
+    CHECK(!empty());
+    return detail::ActorRef(*id_.actor_info_ptr(), 0);
+  }
+
+ private:
+  ActorId<ActorType> id_;
+  void hangup() const {
+    if (empty()) {
+      return;
+    }
+    detail::send_message(as_actor_ref(), ActorMessageCreator::hangup());
+  }
+};
+
+template <class ActorType = Actor>
+class ActorShared {
+ public:
+  using ActorT = ActorType;
+  ActorShared() = default;
+  template <class OtherActorType>
+  ActorShared(ActorId<OtherActorType> id, uint64 token) : id_(std::move(id)), token_(token) {
+    CHECK(token_ != 0);
+  }
+  template <class OtherActorType>
+  ActorShared(ActorShared<OtherActorType> &&other) : id_(other.release()), token_(other.token()) {
+  }
+  template <class OtherActorType>
+  ActorShared(ActorOwn<OtherActorType> &&other) : id_(other.release()), token_(other.token()) {
+  }
+  template <class OtherActorType>
+  ActorShared &operator=(ActorShared<OtherActorType> &&other) {
+    reset(other.release(), other.token());
+  }
+  ActorShared(ActorShared &&other) : id_(other.release()), token_(other.token()) {
+  }
+  ActorShared &operator=(ActorShared &&other) {
+    reset(other.release(), other.token());
+  }
+  ActorShared(const ActorShared &) = delete;
+  ActorShared &operator=(const ActorShared &) = delete;
+  ~ActorShared() {
+    reset();
+  }
+
+  uint64 token() const {
+    return token_;
+  }
+  bool empty() const {
+    return id_.empty();
+  }
+  bool is_alive() const {
+    return id_.is_alive();
+  }
+  ActorId<ActorType> get() const {
+    return id_;
+  }
+  ActorId<ActorType> release();
+  void reset(ActorId<ActorType> other = ActorId<ActorType>(), uint64 link_token = EmptyLinkToken) {
+    static_assert(sizeof(ActorType) > 0, "Can't use ActorShared with incomplete type");
+    hangup();
+    id_ = other;
+    token_ = link_token;
+  }
+  const ActorId<ActorType> *operator->() const {
+    return &id_;
+  }
+
+  detail::ActorRef as_actor_ref() const {
+    CHECK(!empty());
+    return detail::ActorRef(*id_.actor_info_ptr(), token_);
+  }
+
+ private:
+  ActorId<ActorType> id_;
+  uint64 token_;
+
+  void hangup() const {
+  }
+};
+
+// common interface
+template <class SelfT>
+ActorId<SelfT> actor_id(SelfT *self) {
+  CHECK(self);
+  CHECK(static_cast<Actor *>(self) == &ActorExecuteContext::get()->actor());
+  return ActorId<SelfT>(ActorExecuteContext::get()->actor().get_actor_info_ptr());
+}
+
+inline ActorId<> actor_id() {
+  return actor_id(&ActorExecuteContext::get()->actor());
+}
+
+template <class T, class... ArgsT>
+ActorOwn<T> create_actor(ActorOptions options, ArgsT &&... args) {
+  return ActorOwn<T>(ActorId<T>::create(options, std::forward<ArgsT>(args)...));
+}
+
+template <class T, class... ArgsT>
+ActorOwn<T> create_actor(Slice name, ArgsT &&... args) {
+  return ActorOwn<T>(ActorId<T>::create(ActorOptions().with_name(name), std::forward<ArgsT>(args)...));
+}
+
+template <class ActorIdT, class FunctionT, class... ArgsT>
+void send_closure(ActorIdT &&actor_id, FunctionT function, ArgsT &&... args) {
+  using ActorT = typename std::decay_t<ActorIdT>::ActorT;
+  using FunctionClassT = member_function_class_t<FunctionT>;
+  static_assert(std::is_base_of<FunctionClassT, ActorT>::value, "unsafe send_closure");
+
+  ActorIdT id = std::forward<ActorIdT>(actor_id);
+  detail::send_closure(id.as_actor_ref(), function, std::forward<ArgsT>(args)...);
+}
+
+template <class ActorIdT, class FunctionT, class... ArgsT>
+void send_closure_later(ActorIdT &&actor_id, FunctionT function, ArgsT &&... args) {
+  using ActorT = typename std::decay_t<ActorIdT>::ActorT;
+  using FunctionClassT = member_function_class_t<FunctionT>;
+  static_assert(std::is_base_of<FunctionClassT, ActorT>::value, "unsafe send_closure");
+
+  ActorIdT id = std::forward<ActorIdT>(actor_id);
+  detail::send_closure_later(id.as_actor_ref(), function, std::forward<ArgsT>(args)...);
+}
+
+template <class ActorIdT, class... ArgsT>
+void send_lambda(ActorIdT &&actor_id, ArgsT &&... args) {
+  ActorIdT id = std::forward<ActorIdT>(actor_id);
+  detail::send_lambda(id.as_actor_ref(), std::forward<ArgsT>(args)...);
+}
+
+#endif  //!TD_THREAD_UNSUPPORTED
+}  // namespace actor2
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/td/actor/impl2/SchedulerId.h b/libs/tdlib/td/tdactor/td/actor/impl2/SchedulerId.h
new file mode 100644
index 0000000000..5850f1a94c
--- /dev/null
+++ b/libs/tdlib/td/tdactor/td/actor/impl2/SchedulerId.h
@@ -0,0 +1,32 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+
+namespace td {
+namespace actor2 {
+class SchedulerId {
+ public:
+  SchedulerId() : id_(-1) {
+  }
+  explicit SchedulerId(uint8 id) : id_(id) {
+  }
+  bool is_valid() const {
+    return id_ >= 0;
+  }
+  uint8 value() const {
+    CHECK(is_valid());
+    return static_cast<uint8>(id_);
+  }
+
+ private:
+  int32 id_{0};
+};
+}  // namespace actor2
+}  // namespace td
diff --git a/libs/tdlib/td/tdactor/test/actors_bugs.cpp b/libs/tdlib/td/tdactor/test/actors_bugs.cpp
new file mode 100644
index 0000000000..f4267f2818
--- /dev/null
+++ b/libs/tdlib/td/tdactor/test/actors_bugs.cpp
@@ -0,0 +1,47 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/tests.h"
+
+#include "td/actor/Timeout.h"
+
+using namespace td;
+
+TEST(MultiTimeout, bug) {
+  ConcurrentScheduler sched;
+  int threads_n = 0;
+  sched.init(threads_n);
+
+  sched.start();
+  std::unique_ptr<MultiTimeout> multi_timeout;
+  struct Data {
+    MultiTimeout *multi_timeout;
+  };
+  Data data;
+
+  {
+    auto guard = sched.get_current_guard();
+    multi_timeout = std::make_unique<MultiTimeout>();
+    data.multi_timeout = multi_timeout.get();
+    multi_timeout->set_callback([](void *void_data, int64 key) {
+      auto &data = *static_cast<Data *>(void_data);
+      if (key == 1) {
+        data.multi_timeout->cancel_timeout(key + 1);
+        data.multi_timeout->set_timeout_in(key + 2, 1);
+      } else {
+        Scheduler::instance()->finish();
+      }
+    });
+    multi_timeout->set_callback_data(&data);
+    multi_timeout->set_timeout_in(1, 1);
+    multi_timeout->set_timeout_in(2, 2);
+  }
+
+  while (sched.run_main(10)) {
+    // empty
+  }
+  sched.finish();
+}
diff --git a/libs/tdlib/td/tdactor/test/actors_impl2.cpp b/libs/tdlib/td/tdactor/test/actors_impl2.cpp
new file mode 100644
index 0000000000..9185fe8858
--- /dev/null
+++ b/libs/tdlib/td/tdactor/test/actors_impl2.cpp
@@ -0,0 +1,535 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/actor/impl2/ActorLocker.h"
+#include "td/actor/impl2/Scheduler.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/thread.h"
+#include "td/utils/Slice.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tests.h"
+#include "td/utils/Time.h"
+
+#include <array>
+#include <atomic>
+#include <deque>
+#include <memory>
+
+using td::actor2::ActorLocker;
+using td::actor2::ActorSignals;
+using td::actor2::ActorState;
+using td::actor2::SchedulerId;
+
+TEST(Actor2, signals) {
+  ActorSignals signals;
+  signals.add_signal(ActorSignals::Wakeup);
+  signals.add_signal(ActorSignals::Cpu);
+  signals.add_signal(ActorSignals::Kill);
+  signals.clear_signal(ActorSignals::Cpu);
+
+  bool was_kill = false;
+  bool was_wakeup = false;
+  while (!signals.empty()) {
+    auto s = signals.first_signal();
+    if (s == ActorSignals::Kill) {
+      was_kill = true;
+    } else if (s == ActorSignals::Wakeup) {
+      was_wakeup = true;
+    } else {
+      UNREACHABLE();
+    }
+    signals.clear_signal(s);
+  }
+  CHECK(was_kill && was_wakeup);
+}
+
+TEST(Actors2, flags) {
+  ActorState::Flags flags;
+  CHECK(!flags.is_locked());
+  flags.set_locked(true);
+  CHECK(flags.is_locked());
+  flags.set_locked(false);
+  CHECK(!flags.is_locked());
+  flags.set_pause(true);
+
+  flags.set_scheduler_id(SchedulerId{123});
+
+  auto signals = flags.get_signals();
+  CHECK(signals.empty());
+  signals.add_signal(ActorSignals::Cpu);
+  signals.add_signal(ActorSignals::Kill);
+  CHECK(signals.has_signal(ActorSignals::Cpu));
+  CHECK(signals.has_signal(ActorSignals::Kill));
+  flags.set_signals(signals);
+  CHECK(flags.get_signals().raw() == signals.raw()) << flags.get_signals().raw() << " " << signals.raw();
+
+  auto wakeup = ActorSignals{};
+  wakeup.add_signal(ActorSignals::Wakeup);
+
+  flags.add_signals(wakeup);
+  signals.add_signal(ActorSignals::Wakeup);
+  CHECK(flags.get_signals().raw() == signals.raw());
+
+  flags.clear_signals();
+  CHECK(flags.get_signals().empty());
+
+  CHECK(flags.get_scheduler_id().value() == 123);
+  CHECK(flags.is_pause());
+}
+
+TEST(Actor2, locker) {
+  ActorState state;
+
+  ActorSignals kill_signal;
+  kill_signal.add_signal(ActorSignals::Kill);
+
+  ActorSignals wakeup_signal;
+  kill_signal.add_signal(ActorSignals::Wakeup);
+
+  ActorSignals cpu_signal;
+  kill_signal.add_signal(ActorSignals::Cpu);
+
+  {
+    ActorLocker lockerA(&state);
+    ActorLocker lockerB(&state);
+    ActorLocker lockerC(&state);
+
+    CHECK(lockerA.try_lock());
+    CHECK(lockerA.own_lock());
+    auto flagsA = lockerA.flags();
+    CHECK(lockerA.try_unlock(flagsA));
+    CHECK(!lockerA.own_lock());
+
+    CHECK(lockerA.try_lock());
+    CHECK(!lockerB.try_lock());
+    CHECK(!lockerC.try_lock());
+
+    CHECK(lockerB.try_add_signals(kill_signal));
+    CHECK(!lockerC.try_add_signals(wakeup_signal));
+    CHECK(lockerC.try_add_signals(wakeup_signal));
+    CHECK(!lockerC.add_signals(cpu_signal));
+    CHECK(!lockerA.flags().has_signals());
+    CHECK(!lockerA.try_unlock(lockerA.flags()));
+    {
+      auto flags = lockerA.flags();
+      auto signals = flags.get_signals();
+      bool was_kill = false;
+      bool was_wakeup = false;
+      bool was_cpu = false;
+      while (!signals.empty()) {
+        auto s = signals.first_signal();
+        if (s == ActorSignals::Kill) {
+          was_kill = true;
+        } else if (s == ActorSignals::Wakeup) {
+          was_wakeup = true;
+        } else if (s == ActorSignals::Cpu) {
+          was_cpu = true;
+        } else {
+          UNREACHABLE();
+        }
+        signals.clear_signal(s);
+      }
+      CHECK(was_kill && was_wakeup && was_cpu);
+      flags.clear_signals();
+      CHECK(lockerA.try_unlock(flags));
+    }
+  }
+
+  {
+    ActorLocker lockerB(&state);
+    CHECK(lockerB.try_lock());
+    CHECK(lockerB.try_unlock(lockerB.flags()));
+    CHECK(lockerB.add_signals(kill_signal));
+    CHECK(lockerB.flags().get_signals().has_signal(ActorSignals::Kill));
+    auto flags = lockerB.flags();
+    flags.clear_signals();
+    ActorLocker lockerA(&state);
+    CHECK(!lockerA.add_signals(kill_signal));
+    CHECK(!lockerB.try_unlock(flags));
+    CHECK(!lockerA.add_signals(kill_signal));  // do not loose this signal!
+    CHECK(!lockerB.try_unlock(flags));
+    CHECK(lockerB.flags().get_signals().has_signal(ActorSignals::Kill));
+    CHECK(lockerB.try_unlock(flags));
+  }
+
+  {
+    ActorLocker lockerA(&state);
+    CHECK(lockerA.try_lock());
+    auto flags = lockerA.flags();
+    flags.set_pause(true);
+    CHECK(lockerA.try_unlock(flags));
+    //We have to lock, though we can't execute.
+    CHECK(lockerA.add_signals(wakeup_signal));
+  }
+}
+
+#if !TD_THREAD_UNSUPPORTED
+TEST(Actor2, locker_stress) {
+  ActorState state;
+
+  constexpr size_t threads_n = 5;
+  auto stage = [&](std::atomic<int> &value, int need) {
+    value.fetch_add(1, std::memory_order_release);
+    while (value.load(std::memory_order_acquire) < need) {
+      td::this_thread::yield();
+    }
+  };
+
+  struct Node {
+    std::atomic<td::uint32> request{0};
+    td::uint32 response = 0;
+    char pad[64];
+  };
+  std::array<Node, threads_n> nodes;
+  auto do_work = [&]() {
+    for (auto &node : nodes) {
+      auto query = node.request.load(std::memory_order_acquire);
+      if (query) {
+        node.response = query * query;
+        node.request.store(0, std::memory_order_relaxed);
+      }
+    }
+  };
+
+  std::atomic<int> begin{0};
+  std::atomic<int> ready{0};
+  std::atomic<int> check{0};
+  std::atomic<int> finish{0};
+  std::vector<td::thread> threads;
+  for (size_t i = 0; i < threads_n; i++) {
+    threads.push_back(td::thread([&, id = i] {
+      for (size_t i = 1; i < 1000000; i++) {
+        ActorLocker locker(&state);
+        auto need = static_cast<int>(threads_n * i);
+        auto query = static_cast<td::uint32>(id + need);
+        stage(begin, need);
+        nodes[id].request = 0;
+        nodes[id].response = 0;
+        stage(ready, need);
+        if (locker.try_lock()) {
+          nodes[id].response = query * query;
+        } else {
+          auto cpu = ActorSignals::one(ActorSignals::Cpu);
+          nodes[id].request.store(query, std::memory_order_release);
+          locker.add_signals(cpu);
+        }
+        while (locker.own_lock()) {
+          auto flags = locker.flags();
+          auto signals = flags.get_signals();
+          if (!signals.empty()) {
+            do_work();
+          }
+          flags.clear_signals();
+          locker.try_unlock(flags);
+        }
+
+        stage(check, need);
+        if (id == 0) {
+          CHECK(locker.add_signals(ActorSignals{}));
+          CHECK(!locker.flags().has_signals());
+          CHECK(locker.try_unlock(locker.flags()));
+          for (size_t thread_id = 0; thread_id < threads_n; thread_id++) {
+            CHECK(nodes[thread_id].response ==
+                  static_cast<td::uint32>(thread_id + need) * static_cast<td::uint32>(thread_id + need))
+                << td::tag("thread", thread_id) << " " << nodes[thread_id].response << " "
+                << nodes[thread_id].request.load();
+          }
+        }
+      }
+    }));
+  }
+  for (auto &thread : threads) {
+    thread.join();
+  }
+}
+
+namespace {
+const size_t BUF_SIZE = 1024 * 1024;
+char buf[BUF_SIZE];
+td::StringBuilder sb(td::MutableSlice(buf, BUF_SIZE - 1));
+}  // namespace
+
+TEST(Actor2, executor_simple) {
+  using namespace td;
+  using namespace td::actor2;
+  struct Dispatcher : public SchedulerDispatcher {
+    void add_to_queue(ActorInfoPtr ptr, SchedulerId scheduler_id, bool need_poll) override {
+      queue.push_back(std::move(ptr));
+    }
+    void set_alarm_timestamp(const ActorInfoPtr &actor_info_ptr, Timestamp timestamp) override {
+      UNREACHABLE();
+    }
+    SchedulerId get_scheduler_id() const override {
+      return SchedulerId{0};
+    }
+    std::deque<ActorInfoPtr> queue;
+  };
+  Dispatcher dispatcher;
+
+  class TestActor : public Actor {
+   public:
+    void close() {
+      stop();
+    }
+
+   private:
+    void start_up() override {
+      sb << "StartUp";
+    }
+    void tear_down() override {
+      sb << "TearDown";
+    }
+  };
+  ActorInfoCreator actor_info_creator;
+  auto actor = actor_info_creator.create(
+      std::make_unique<TestActor>(), ActorInfoCreator::Options().on_scheduler(SchedulerId{0}).with_name("TestActor"));
+  dispatcher.add_to_queue(actor, SchedulerId{0}, false);
+
+  {
+    ActorExecutor executor(*actor, dispatcher, ActorExecutor::Options());
+    CHECK(executor.can_send());
+    CHECK(executor.can_send_immediate());
+    CHECK(sb.as_cslice() == "StartUp") << sb.as_cslice();
+    sb.clear();
+    executor.send(ActorMessageCreator::lambda([&] { sb << "A"; }));
+    CHECK(sb.as_cslice() == "A") << sb.as_cslice();
+    sb.clear();
+    auto big_message = ActorMessageCreator::lambda([&] { sb << "big"; });
+    big_message.set_big();
+    executor.send(std::move(big_message));
+    CHECK(sb.as_cslice() == "") << sb.as_cslice();
+    executor.send(ActorMessageCreator::lambda([&] { sb << "A"; }));
+    CHECK(sb.as_cslice() == "") << sb.as_cslice();
+  }
+  CHECK(dispatcher.queue.size() == 1);
+  { ActorExecutor executor(*actor, dispatcher, ActorExecutor::Options().with_from_queue()); }
+  CHECK(dispatcher.queue.size() == 1);
+  dispatcher.queue.clear();
+  CHECK(sb.as_cslice() == "bigA") << sb.as_cslice();
+  sb.clear();
+  {
+    ActorExecutor executor(*actor, dispatcher, ActorExecutor::Options());
+    executor.send(
+        ActorMessageCreator::lambda([&] { static_cast<TestActor &>(ActorExecuteContext::get()->actor()).close(); }));
+  }
+  CHECK(sb.as_cslice() == "TearDown") << sb.as_cslice();
+  sb.clear();
+  CHECK(!actor->has_actor());
+  {
+    ActorExecutor executor(*actor, dispatcher, ActorExecutor::Options());
+    executor.send(
+        ActorMessageCreator::lambda([&] { static_cast<TestActor &>(ActorExecuteContext::get()->actor()).close(); }));
+  }
+  CHECK(dispatcher.queue.empty());
+  CHECK(sb.as_cslice() == "");
+}
+
+using namespace td::actor2;
+using td::uint32;
+static std::atomic<int> cnt;
+class Worker : public Actor {
+ public:
+  void query(uint32 x, ActorInfoPtr master);
+  void close() {
+    stop();
+  }
+};
+class Master : public Actor {
+ public:
+  void on_result(uint32 x, uint32 y) {
+    loop();
+  }
+
+ private:
+  uint32 l = 0;
+  uint32 r = 100000;
+  ActorInfoPtr worker;
+  void start_up() override {
+    worker = detail::create_actor<Worker>(ActorOptions().with_name("Master"));
+    loop();
+  }
+  void loop() override {
+    l++;
+    if (l == r) {
+      if (!--cnt) {
+        SchedulerContext::get()->stop();
+      }
+      detail::send_closure(*worker, &Worker::close);
+      stop();
+      return;
+    }
+    detail::send_lambda(*worker,
+                        [x = l, self = get_actor_info_ptr()] { detail::current_actor<Worker>().query(x, self); });
+  }
+};
+
+void Worker::query(uint32 x, ActorInfoPtr master) {
+  auto y = x;
+  for (int i = 0; i < 100; i++) {
+    y = y * y;
+  }
+  detail::send_lambda(*master, [result = y, x] { detail::current_actor<Master>().on_result(x, result); });
+}
+
+TEST(Actor2, scheduler_simple) {
+  auto group_info = std::make_shared<SchedulerGroupInfo>(1);
+  Scheduler scheduler{group_info, SchedulerId{0}, 2};
+  scheduler.start();
+  scheduler.run_in_context([] {
+    cnt = 10;
+    for (int i = 0; i < 10; i++) {
+      detail::create_actor<Master>(ActorOptions().with_name("Master"));
+    }
+  });
+  while (scheduler.run(1000)) {
+  }
+  Scheduler::close_scheduler_group(*group_info);
+}
+
+TEST(Actor2, actor_id_simple) {
+  auto group_info = std::make_shared<SchedulerGroupInfo>(1);
+  Scheduler scheduler{group_info, SchedulerId{0}, 2};
+  sb.clear();
+  scheduler.start();
+
+  scheduler.run_in_context([] {
+    class A : public Actor {
+     public:
+      A(int value) : value_(value) {
+        sb << "A" << value_;
+      }
+      void hello() {
+        sb << "hello";
+      }
+      ~A() {
+        sb << "~A";
+        if (--cnt <= 0) {
+          SchedulerContext::get()->stop();
+        }
+      }
+
+     private:
+      int value_;
+    };
+    cnt = 1;
+    auto id = create_actor<A>("A", 123);
+    CHECK(sb.as_cslice() == "A123");
+    sb.clear();
+    send_closure(id, &A::hello);
+  });
+  while (scheduler.run(1000)) {
+  }
+  CHECK(sb.as_cslice() == "hello~A");
+  Scheduler::close_scheduler_group(*group_info);
+  sb.clear();
+}
+
+TEST(Actor2, actor_creation) {
+  auto group_info = std::make_shared<SchedulerGroupInfo>(1);
+  Scheduler scheduler{group_info, SchedulerId{0}, 1};
+  scheduler.start();
+
+  scheduler.run_in_context([]() mutable {
+    class B;
+    class A : public Actor {
+     public:
+      void f() {
+        check();
+        stop();
+      }
+
+     private:
+      void start_up() override {
+        check();
+        create_actor<B>("Simple", actor_id(this)).release();
+      }
+
+      void check() {
+        auto &context = *SchedulerContext::get();
+        CHECK(context.has_poll());
+        context.get_poll();
+      }
+
+      void tear_down() override {
+        if (--cnt <= 0) {
+          SchedulerContext::get()->stop();
+        }
+      }
+    };
+
+    class B : public Actor {
+     public:
+      B(ActorId<A> a) : a_(a) {
+      }
+
+     private:
+      void start_up() override {
+        auto &context = *SchedulerContext::get();
+        CHECK(!context.has_poll());
+        send_closure(a_, &A::f);
+        stop();
+      }
+      void tear_down() override {
+        if (--cnt <= 0) {
+          SchedulerContext::get()->stop();
+        }
+      }
+      ActorId<A> a_;
+    };
+    cnt = 2;
+    create_actor<A>(ActorOptions().with_name("Poll").with_poll()).release();
+  });
+  while (scheduler.run(1000)) {
+  }
+  scheduler.stop();
+  Scheduler::close_scheduler_group(*group_info);
+}
+
+TEST(Actor2, actor_timeout_simple) {
+  auto group_info = std::make_shared<SchedulerGroupInfo>(1);
+  Scheduler scheduler{group_info, SchedulerId{0}, 2};
+  sb.clear();
+  scheduler.start();
+
+  scheduler.run_in_context([] {
+    class A : public Actor {
+     public:
+      void start_up() override {
+        set_timeout();
+      }
+      void alarm() override {
+        double diff = td::Time::now() - expected_timeout_;
+        CHECK(-0.001 < diff && diff < 0.1) << diff;
+        if (cnt_-- > 0) {
+          set_timeout();
+        } else {
+          stop();
+        }
+      }
+
+      void tear_down() override {
+        SchedulerContext::get()->stop();
+      }
+
+     private:
+      double expected_timeout_;
+      int cnt_ = 5;
+      void set_timeout() {
+        auto wakeup_timestamp = td::Timestamp::in(0.1);
+        expected_timeout_ = wakeup_timestamp.at();
+        alarm_timestamp() = wakeup_timestamp;
+      }
+    };
+    create_actor<A>(ActorInfoCreator::Options().with_name("A").with_poll()).release();
+  });
+  while (scheduler.run(1000)) {
+  }
+  Scheduler::close_scheduler_group(*group_info);
+  sb.clear();
+}
+#endif  //!TD_THREAD_UNSUPPORTED
diff --git a/libs/tdlib/td/tdactor/test/actors_main.cpp b/libs/tdlib/td/tdactor/test/actors_main.cpp
new file mode 100644
index 0000000000..ffceacc595
--- /dev/null
+++ b/libs/tdlib/td/tdactor/test/actors_main.cpp
@@ -0,0 +1,463 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/tests.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/Random.h"
+
+#include <limits>
+#include <map>
+#include <utility>
+
+using namespace td;
+
+REGISTER_TESTS(actors_main);
+
+namespace {
+
+template <class ContainerT>
+static typename ContainerT::value_type &rand_elem(ContainerT &cont) {
+  CHECK(0 < cont.size() && cont.size() <= static_cast<size_t>(std::numeric_limits<int>::max()));
+  return cont[Random::fast(0, static_cast<int>(cont.size()) - 1)];
+}
+
+static uint32 fast_pow_mod_uint32(uint32 x, uint32 p) {
+  uint32 res = 1;
+  while (p) {
+    if (p & 1) {
+      res *= x;
+    }
+    x *= x;
+    p >>= 1;
+  }
+  return res;
+}
+
+static uint32 slow_pow_mod_uint32(uint32 x, uint32 p) {
+  uint32 res = 1;
+  for (uint32 i = 0; i < p; i++) {
+    res *= x;
+  }
+  return res;
+}
+
+struct Query {
+  uint32 query_id;
+  uint32 result;
+  std::vector<int> todo;
+  Query() = default;
+  Query(const Query &) = delete;
+  Query &operator=(const Query &) = delete;
+  Query(Query &&) = default;
+  Query &operator=(Query &&) = default;
+  ~Query() {
+    CHECK(todo.empty()) << "Query lost";
+  }
+  int next_pow() {
+    CHECK(!todo.empty());
+    int res = todo.back();
+    todo.pop_back();
+    return res;
+  }
+  bool ready() {
+    return todo.empty();
+  }
+};
+
+static uint32 fast_calc(Query &q) {
+  uint32 result = q.result;
+  for (auto x : q.todo) {
+    result = fast_pow_mod_uint32(result, x);
+  }
+  return result;
+}
+
+class Worker final : public Actor {
+ public:
+  explicit Worker(int threads_n) : threads_n_(threads_n) {
+  }
+  void query(PromiseActor<uint32> &&promise, uint32 x, uint32 p) {
+    uint32 result = slow_pow_mod_uint32(x, p);
+    promise.set_value(std::move(result));
+
+    (void)threads_n_;
+    // if (threads_n_ > 1 && Random::fast(0, 9) == 0) {
+    // migrate(Random::fast(2, threads_n));
+    //}
+  }
+
+ private:
+  int threads_n_;
+};
+
+class QueryActor final : public Actor {
+ public:
+  class Callback {
+   public:
+    Callback() = default;
+    Callback(const Callback &) = delete;
+    Callback &operator=(const Callback &) = delete;
+    Callback(Callback &&) = delete;
+    Callback &operator=(Callback &&) = delete;
+    virtual ~Callback() = default;
+    virtual void on_result(Query &&query) = 0;
+    virtual void on_closed() = 0;
+  };
+
+  explicit QueryActor(int threads_n) : threads_n_(threads_n) {
+  }
+
+  void set_callback(std::unique_ptr<Callback> callback) {
+    callback_ = std::move(callback);
+  }
+  void set_workers(std::vector<ActorId<Worker>> workers) {
+    workers_ = std::move(workers);
+  }
+
+  void query(Query &&query) {
+    uint32 x = query.result;
+    uint32 p = query.next_pow();
+    if (Random::fast(0, 3) && (p <= 1000 || workers_.empty())) {
+      query.result = slow_pow_mod_uint32(x, p);
+      callback_->on_result(std::move(query));
+    } else {
+      auto future = send_promise(rand_elem(workers_), Random::fast(0, 3) == 0 ? 0 : Send::later, &Worker::query, x, p);
+      if (future.is_ready()) {
+        query.result = future.move_as_ok();
+        callback_->on_result(std::move(query));
+      } else {
+        future.set_event(EventCreator::raw(actor_id(), query.query_id));
+        auto query_id = query.query_id;
+        pending_.insert(std::make_pair(query_id, std::make_pair(std::move(future), std::move(query))));
+      }
+    }
+    if (threads_n_ > 1 && Random::fast(0, 9) == 0) {
+      migrate(Random::fast(2, threads_n_));
+    }
+  }
+
+  void raw_event(const Event::Raw &event) override {
+    uint32 id = event.u32;
+    auto it = pending_.find(id);
+    auto future = std::move(it->second.first);
+    auto query = std::move(it->second.second);
+    pending_.erase(it);
+    CHECK(future.is_ready());
+    query.result = future.move_as_ok();
+    callback_->on_result(std::move(query));
+  }
+
+  void close() {
+    callback_->on_closed();
+    stop();
+  }
+
+  void on_start_migrate(int32 sched_id) override {
+    for (auto &it : pending_) {
+      start_migrate(it.second.first, sched_id);
+    }
+  }
+  void on_finish_migrate() override {
+    for (auto &it : pending_) {
+      finish_migrate(it.second.first);
+    }
+  }
+
+ private:
+  unique_ptr<Callback> callback_;
+  std::map<uint32, std::pair<FutureActor<uint32>, Query>> pending_;
+  std::vector<ActorId<Worker>> workers_;
+  int threads_n_;
+};
+
+class MainQueryActor final : public Actor {
+  class QueryActorCallback : public QueryActor::Callback {
+   public:
+    void on_result(Query &&query) override {
+      if (query.ready()) {
+        send_closure(parent_id_, &MainQueryActor::on_result, std::move(query));
+      } else {
+        send_closure(next_solver_, &QueryActor::query, std::move(query));
+      }
+    }
+    void on_closed() override {
+      send_closure(parent_id_, &MainQueryActor::on_closed);
+    }
+    QueryActorCallback(ActorId<MainQueryActor> parent_id, ActorId<QueryActor> next_solver)
+        : parent_id_(parent_id), next_solver_(next_solver) {
+    }
+
+   private:
+    ActorId<MainQueryActor> parent_id_;
+    ActorId<QueryActor> next_solver_;
+  };
+
+  const int ACTORS_CNT = 10;
+  const int WORKERS_CNT = 4;
+
+ public:
+  explicit MainQueryActor(int threads_n) : threads_n_(threads_n) {
+  }
+
+  void start_up() override {
+    actors_.resize(ACTORS_CNT);
+    for (auto &actor : actors_) {
+      auto actor_ptr = make_unique<QueryActor>(threads_n_);
+      actor = register_actor("QueryActor", std::move(actor_ptr), threads_n_ > 1 ? Random::fast(2, threads_n_) : 0)
+                  .release();
+    }
+
+    workers_.resize(WORKERS_CNT);
+    for (auto &worker : workers_) {
+      auto actor_ptr = make_unique<Worker>(threads_n_);
+      worker =
+          register_actor("Worker", std::move(actor_ptr), threads_n_ > 1 ? Random::fast(2, threads_n_) : 0).release();
+    }
+
+    for (int i = 0; i < ACTORS_CNT; i++) {
+      ref_cnt_++;
+      send_closure(actors_[i], &QueryActor::set_callback,
+                   make_unique<QueryActorCallback>(actor_id(this), actors_[(i + 1) % ACTORS_CNT]));
+      send_closure(actors_[i], &QueryActor::set_workers, workers_);
+    }
+    yield();
+  }
+
+  void on_result(Query &&query) {
+    CHECK(query.ready());
+    CHECK(query.result == expected_[query.query_id]);
+    in_cnt_++;
+    wakeup();
+  }
+
+  Query create_query() {
+    Query q;
+    q.query_id = (query_id_ += 2);
+    q.result = q.query_id;
+    q.todo = {1, 1, 1, 1, 1, 1, 1, 1, 10000};
+    expected_[q.query_id] = fast_calc(q);
+    return q;
+  }
+
+  void on_closed() {
+    ref_cnt_--;
+    if (ref_cnt_ == 0) {
+      Scheduler::instance()->finish();
+    }
+  }
+
+  void wakeup() override {
+    int cnt = 100000;
+    while (out_cnt_ < in_cnt_ + 100 && out_cnt_ < cnt) {
+      if (Random::fast(0, 1)) {
+        send_closure(rand_elem(actors_), &QueryActor::query, create_query());
+      } else {
+        send_closure_later(rand_elem(actors_), &QueryActor::query, create_query());
+      }
+      out_cnt_++;
+    }
+    if (in_cnt_ == cnt) {
+      in_cnt_++;
+      ref_cnt_--;
+      for (auto &actor : actors_) {
+        send_closure(actor, &QueryActor::close);
+      }
+    }
+  }
+
+ private:
+  std::map<uint32, uint32> expected_;
+  std::vector<ActorId<QueryActor>> actors_;
+  std::vector<ActorId<Worker>> workers_;
+  int out_cnt_ = 0;
+  int in_cnt_ = 0;
+  int query_id_ = 1;
+  int ref_cnt_ = 1;
+  int threads_n_;
+};
+
+class SimpleActor final : public Actor {
+ public:
+  explicit SimpleActor(int32 threads_n) : threads_n_(threads_n) {
+  }
+  void start_up() override {
+    auto actor_ptr = make_unique<Worker>(threads_n_);
+    worker_ =
+        register_actor("Worker", std::move(actor_ptr), threads_n_ > 1 ? Random::fast(2, threads_n_) : 0).release();
+    yield();
+  }
+
+  void wakeup() override {
+    if (q_ == 100000) {
+      Scheduler::instance()->finish();
+      stop();
+      return;
+    }
+    q_++;
+    p_ = Random::fast(0, 1) ? 1 : 10000;
+    auto future = send_promise(worker_, Random::fast(0, 3) == 0 ? 0 : Send::later, &Worker::query, q_, p_);
+    if (future.is_ready()) {
+      auto result = future.move_as_ok();
+      CHECK(result == fast_pow_mod_uint32(q_, p_));
+      yield();
+    } else {
+      future.set_event(EventCreator::raw(actor_id(), nullptr));
+      future_ = std::move(future);
+    }
+    // if (threads_n_ > 1 && Random::fast(0, 2) == 0) {
+    // migrate(Random::fast(1, threads_n));
+    //}
+  }
+  void raw_event(const Event::Raw &event) override {
+    auto result = future_.move_as_ok();
+    CHECK(result == fast_pow_mod_uint32(q_, p_));
+    yield();
+  }
+
+  void on_start_migrate(int32 sched_id) override {
+    start_migrate(future_, sched_id);
+  }
+  void on_finish_migrate() override {
+    finish_migrate(future_);
+  }
+
+ private:
+  int32 threads_n_;
+  ActorId<Worker> worker_;
+  FutureActor<uint32> future_;
+  uint32 q_ = 1;
+  uint32 p_;
+};
+}  // namespace
+
+class SendToDead : public Actor {
+ public:
+  class Parent : public Actor {
+   public:
+    explicit Parent(ActorShared<> parent, int ttl = 3) : parent_(std::move(parent)), ttl_(ttl) {
+    }
+    void start_up() override {
+      set_timeout_in(Random::fast_uint32() % 3 * 0.001);
+      if (ttl_ != 0) {
+        child_ = create_actor_on_scheduler<Parent>(
+            "Child", Random::fast_uint32() % Scheduler::instance()->sched_count(), actor_shared(), ttl_ - 1);
+      }
+    }
+    void timeout_expired() override {
+      stop();
+    }
+
+   private:
+    ActorOwn<Parent> child_;
+    ActorShared<> parent_;
+    int ttl_;
+  };
+
+  void start_up() override {
+    for (int i = 0; i < 2000; i++) {
+      create_actor_on_scheduler<Parent>("Parent", Random::fast_uint32() % Scheduler::instance()->sched_count(),
+                                        create_reference(), 4)
+          .release();
+    }
+  }
+
+  ActorShared<> create_reference() {
+    ref_cnt_++;
+    return actor_shared();
+  }
+  void hangup_shared() override {
+    ref_cnt_--;
+    if (ref_cnt_ == 0) {
+      ttl_--;
+      if (ttl_ <= 0) {
+        Scheduler::instance()->finish();
+        stop();
+      } else {
+        start_up();
+      }
+    }
+  }
+
+  uint32 ttl_{50};
+  uint32 ref_cnt_{0};
+};
+
+TEST(Actors, send_to_dead) {
+  //TODO: fix CHECK(storage_count_.load() == 0)
+  return;
+  ConcurrentScheduler sched;
+  int threads_n = 5;
+  sched.init(threads_n);
+
+  sched.create_actor_unsafe<SendToDead>(0, "manager").release();
+  sched.start();
+  while (sched.run_main(10)) {
+    // empty
+  }
+  sched.finish();
+}
+
+TEST(Actors, main_simple) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(DEBUG));
+
+  ConcurrentScheduler sched;
+  int threads_n = 3;
+  sched.init(threads_n);
+
+  sched.create_actor_unsafe<SimpleActor>(threads_n > 1 ? 1 : 0, "simple", threads_n).release();
+  sched.start();
+  while (sched.run_main(10)) {
+    // empty
+  }
+  sched.finish();
+}
+
+TEST(Actors, main) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(DEBUG));
+
+  ConcurrentScheduler sched;
+  int threads_n = 9;
+  sched.init(threads_n);
+
+  sched.create_actor_unsafe<MainQueryActor>(threads_n > 1 ? 1 : 0, "manager", threads_n).release();
+  sched.start();
+  while (sched.run_main(10)) {
+    // empty
+  }
+  sched.finish();
+}
+
+class DoAfterStop : public Actor {
+ public:
+  void loop() override {
+    ptr = std::make_unique<int>(10);
+    stop();
+    CHECK(*ptr == 10);
+    Scheduler::instance()->finish();
+  }
+
+ private:
+  std::unique_ptr<int> ptr;
+};
+
+TEST(Actors, do_after_stop) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(DEBUG));
+
+  ConcurrentScheduler sched;
+  int threads_n = 0;
+  sched.init(threads_n);
+
+  sched.create_actor_unsafe<DoAfterStop>(0, "manager").release();
+  sched.start();
+  while (sched.run_main(10)) {
+    // empty
+  }
+  sched.finish();
+}
diff --git a/libs/tdlib/td/tdactor/test/actors_simple.cpp b/libs/tdlib/td/tdactor/test/actors_simple.cpp
new file mode 100644
index 0000000000..c0a6c32b61
--- /dev/null
+++ b/libs/tdlib/td/tdactor/test/actors_simple.cpp
@@ -0,0 +1,622 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/tests.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/MultiPromise.h"
+#include "td/actor/PromiseFuture.h"
+#include "td/actor/SleepActor.h"
+#include "td/actor/Timeout.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/Observer.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+
+#include <tuple>
+
+REGISTER_TESTS(actors_simple)
+
+namespace {
+using namespace td;
+
+static const size_t BUF_SIZE = 1024 * 1024;
+static char buf[BUF_SIZE];
+static char buf2[BUF_SIZE];
+static StringBuilder sb(MutableSlice(buf, BUF_SIZE - 1));
+static StringBuilder sb2(MutableSlice(buf2, BUF_SIZE - 1));
+
+TEST(Actors, SendLater) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR));
+  sb.clear();
+  Scheduler scheduler;
+  scheduler.init();
+
+  auto guard = scheduler.get_guard();
+  class Worker : public Actor {
+   public:
+    void f() {
+      sb << "A";
+    }
+  };
+  auto id = create_actor<Worker>("Worker");
+  scheduler.run_no_guard(0);
+  send_closure(id, &Worker::f);
+  send_closure_later(id, &Worker::f);
+  send_closure(id, &Worker::f);
+  ASSERT_STREQ("A", sb.as_cslice().c_str());
+  scheduler.run_no_guard(0);
+  ASSERT_STREQ("AAA", sb.as_cslice().c_str());
+}
+
+class X {
+ public:
+  X() {
+    sb << "[cnstr_default]";
+  }
+  X(const X &) {
+    sb << "[cnstr_copy]";
+  }
+  X(X &&) {
+    sb << "[cnstr_move]";
+  }
+  X &operator=(const X &) {
+    sb << "[set_copy]";
+    return *this;
+  }
+  X &operator=(X &&) {
+    sb << "[set_move]";
+    return *this;
+  }
+  ~X() = default;
+};
+
+class XReceiver final : public Actor {
+ public:
+  void by_const_ref(const X &) {
+    sb << "[by_const_ref]";
+  }
+  void by_lvalue_ref(const X &) {
+    sb << "[by_lvalue_ref]";
+  }
+  void by_value(X) {
+    sb << "[by_value]";
+  }
+};
+
+TEST(Actors, simple_pass_event_arguments) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(DEBUG));
+  Scheduler scheduler;
+  scheduler.init();
+
+  auto guard = scheduler.get_guard();
+  auto id = create_actor<XReceiver>("XR").release();
+  scheduler.run_no_guard(0);
+
+  X x;
+
+  // check tuple
+  // std::tuple<X> tx;
+  // sb.clear();
+  // std::tuple<X> ty(std::move(tx));
+  // tx = std::move(ty);
+  // ASSERT_STREQ("[cnstr_move]", sb.as_cslice().c_str());
+
+  // Send temporary object
+
+  // Tmp-->ConstRef
+  sb.clear();
+  send_closure(id, &XReceiver::by_const_ref, X());
+  ASSERT_STREQ("[cnstr_default][by_const_ref]", sb.as_cslice().c_str());
+
+  // Tmp-->ConstRef (Delayed)
+  sb.clear();
+  send_closure_later(id, &XReceiver::by_const_ref, X());
+  scheduler.run_no_guard(0);
+  // LOG(ERROR) << sb.as_cslice();
+  ASSERT_STREQ("[cnstr_default][cnstr_move][by_const_ref]", sb.as_cslice().c_str());
+
+  // Tmp-->LvalueRef
+  sb.clear();
+  send_closure(id, &XReceiver::by_lvalue_ref, X());
+  ASSERT_STREQ("[cnstr_default][by_lvalue_ref]", sb.as_cslice().c_str());
+
+  // Tmp-->LvalueRef (Delayed)
+  sb.clear();
+  send_closure_later(id, &XReceiver::by_lvalue_ref, X());
+  scheduler.run_no_guard(0);
+  ASSERT_STREQ("[cnstr_default][cnstr_move][by_lvalue_ref]", sb.as_cslice().c_str());
+
+  // Tmp-->Value
+  sb.clear();
+  send_closure(id, &XReceiver::by_value, X());
+  ASSERT_STREQ("[cnstr_default][cnstr_move][by_value]", sb.as_cslice().c_str());
+
+  // Tmp-->Value (Delayed)
+  sb.clear();
+  send_closure_later(id, &XReceiver::by_value, X());
+  scheduler.run_no_guard(0);
+  ASSERT_STREQ("[cnstr_default][cnstr_move][cnstr_move][by_value]", sb.as_cslice().c_str());
+
+  // Var-->ConstRef
+  sb.clear();
+  send_closure(id, &XReceiver::by_const_ref, x);
+  ASSERT_STREQ("[by_const_ref]", sb.as_cslice().c_str());
+
+  // Var-->ConstRef (Delayed)
+  sb.clear();
+  send_closure_later(id, &XReceiver::by_const_ref, x);
+  scheduler.run_no_guard(0);
+  ASSERT_STREQ("[cnstr_copy][by_const_ref]", sb.as_cslice().c_str());
+
+  // Var-->LvalueRef
+  // Var-->LvalueRef (Delayed)
+  // CE or stange behaviour
+
+  // Var-->Value
+  sb.clear();
+  send_closure(id, &XReceiver::by_value, x);
+  ASSERT_STREQ("[cnstr_copy][by_value]", sb.as_cslice().c_str());
+
+  // Var-->Value (Delayed)
+  sb.clear();
+  send_closure_later(id, &XReceiver::by_value, x);
+  scheduler.run_no_guard(0);
+  ASSERT_STREQ("[cnstr_copy][cnstr_move][by_value]", sb.as_cslice().c_str());
+}
+
+class PrintChar final : public Actor {
+ public:
+  PrintChar(char c, int cnt) : char_(c), cnt_(cnt) {
+  }
+  void start_up() override {
+    yield();
+  }
+  void wakeup() override {
+    if (cnt_ == 0) {
+      stop();
+    } else {
+      sb << char_;
+      cnt_--;
+      yield();
+    }
+  }
+
+ private:
+  char char_;
+  int cnt_;
+};
+}  // namespace
+
+//
+// Yield must add actor to the end of queue
+//
+TEST(Actors, simple_hand_yield) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(DEBUG));
+  Scheduler scheduler;
+  scheduler.init();
+  sb.clear();
+  int cnt = 1000;
+  {
+    auto guard = scheduler.get_guard();
+    create_actor<PrintChar>("PrintA", 'A', cnt).release();
+    create_actor<PrintChar>("PrintB", 'B', cnt).release();
+    create_actor<PrintChar>("PrintC", 'C', cnt).release();
+  }
+  scheduler.run(0);
+  std::string expected;
+  for (int i = 0; i < cnt; i++) {
+    expected += "ABC";
+  }
+  ASSERT_STREQ(expected.c_str(), sb.as_cslice().c_str());
+}
+
+class Ball {
+ public:
+  friend void start_migrate(Ball &ball, int32 sched_id) {
+    sb << "start";
+  }
+  friend void finish_migrate(Ball &ball) {
+    sb2 << "finish";
+  }
+};
+
+class Pong final : public Actor {
+ public:
+  void pong(Ball ball) {
+    Scheduler::instance()->finish();
+  }
+};
+
+class Ping final : public Actor {
+ public:
+  explicit Ping(ActorId<Pong> pong) : pong_(pong) {
+  }
+  void start_up() override {
+    send_closure(pong_, &Pong::pong, Ball());
+  }
+
+ private:
+  ActorId<Pong> pong_;
+};
+
+TEST(Actors, simple_migrate) {
+  sb.clear();
+  sb2.clear();
+
+  ConcurrentScheduler scheduler;
+  scheduler.init(2);
+  auto pong = scheduler.create_actor_unsafe<Pong>(2, "Pong").release();
+  scheduler.create_actor_unsafe<Ping>(1, "Ping", pong).release();
+  scheduler.start();
+  while (scheduler.run_main(10)) {
+  }
+  scheduler.finish();
+#if TD_THREAD_UNSUPPORTED || TD_EVENTFD_UNSUPPORTED
+  ASSERT_STREQ("", sb.as_cslice().c_str());
+  ASSERT_STREQ("", sb2.as_cslice().c_str());
+#else
+  ASSERT_STREQ("start", sb.as_cslice().c_str());
+  ASSERT_STREQ("finish", sb2.as_cslice().c_str());
+#endif
+}
+
+class OpenClose final : public Actor {
+ public:
+  explicit OpenClose(int cnt) : cnt_(cnt) {
+  }
+  void start_up() override {
+    yield();
+  }
+  void wakeup() override {
+    ObserverBase *observer = reinterpret_cast<ObserverBase *>(123);
+    if (cnt_ > 0) {
+      auto r_file_fd = FileFd::open("server", FileFd::Read | FileFd::Create);
+      CHECK(r_file_fd.is_ok()) << r_file_fd.error();
+      auto file_fd = r_file_fd.move_as_ok();
+      // LOG(ERROR) << file_fd.get_native_fd();
+      file_fd.get_fd().set_observer(observer);
+      file_fd.close();
+      cnt_--;
+      yield();
+    } else {
+      Scheduler::instance()->finish();
+    }
+  }
+
+ private:
+  int cnt_;
+};
+
+TEST(Actors, open_close) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR));
+  ConcurrentScheduler scheduler;
+  scheduler.init(2);
+  int cnt = 1000000;
+#if TD_WINDOWS || TD_ANDROID
+  // TODO(perf) optimize
+  cnt = 100;
+#endif
+  scheduler.create_actor_unsafe<OpenClose>(1, "A", cnt).release();
+  scheduler.create_actor_unsafe<OpenClose>(2, "B", cnt).release();
+  scheduler.start();
+  while (scheduler.run_main(10)) {
+  }
+  scheduler.finish();
+}
+
+namespace {
+class MsgActor : public Actor {
+ public:
+  virtual void msg() = 0;
+};
+
+class Slave : public Actor {
+ public:
+  ActorId<MsgActor> msg;
+  explicit Slave(ActorId<MsgActor> msg) : msg(msg) {
+  }
+  void hangup() override {
+    send_closure(msg, &MsgActor::msg);
+  }
+};
+
+class MasterActor : public MsgActor {
+ public:
+  void loop() override {
+    alive_ = true;
+    slave = create_actor<Slave>("slave", static_cast<ActorId<MsgActor>>(actor_id(this)));
+    stop();
+  }
+  ActorOwn<Slave> slave;
+
+  MasterActor() = default;
+  MasterActor(const MasterActor &) = delete;
+  MasterActor &operator=(const MasterActor &) = delete;
+  MasterActor(MasterActor &&) = delete;
+  MasterActor &operator=(MasterActor &&) = delete;
+  ~MasterActor() override {
+    alive_ = 987654321;
+  }
+  void msg() override {
+    CHECK(alive_ == 123456789);
+  }
+  uint64 alive_ = 123456789;
+};
+}  // namespace
+
+TEST(Actors, call_after_destruct) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(DEBUG));
+  Scheduler scheduler;
+  scheduler.init();
+  {
+    auto guard = scheduler.get_guard();
+    create_actor<MasterActor>("Master").release();
+  }
+  scheduler.run(0);
+}
+
+class LinkTokenSlave : public Actor {
+ public:
+  explicit LinkTokenSlave(ActorShared<> parent) : parent_(std::move(parent)) {
+  }
+  void add(uint64 link_token) {
+    CHECK(link_token == get_link_token());
+  }
+  void close() {
+    stop();
+  }
+
+ private:
+  ActorShared<> parent_;
+};
+
+class LinkTokenMasterActor : public Actor {
+ public:
+  explicit LinkTokenMasterActor(int cnt) : cnt_(cnt) {
+  }
+  void start_up() override {
+    child_ = create_actor<LinkTokenSlave>("Slave", actor_shared(this, 123)).release();
+    yield();
+  }
+  void loop() override {
+    for (int i = 0; i < 100 && cnt_ > 0; cnt_--, i++) {
+      switch (i % 4) {
+        case 0: {
+          send_closure(ActorShared<LinkTokenSlave>(child_, cnt_ + 1), &LinkTokenSlave::add, cnt_ + 1);
+          break;
+        }
+        case 1: {
+          send_closure_later(ActorShared<LinkTokenSlave>(child_, cnt_ + 1), &LinkTokenSlave::add, cnt_ + 1);
+          break;
+        }
+        case 2: {
+          EventCreator::closure(ActorShared<LinkTokenSlave>(child_, cnt_ + 1), &LinkTokenSlave::add, cnt_ + 1)
+              .try_emit();
+          break;
+        }
+        case 3: {
+          EventCreator::closure(ActorShared<LinkTokenSlave>(child_, cnt_ + 1), &LinkTokenSlave::add, cnt_ + 1)
+              .try_emit_later();
+          break;
+        }
+      }
+    }
+    if (cnt_ == 0) {
+      send_closure(child_, &LinkTokenSlave::close);
+    } else {
+      yield();
+    }
+  }
+
+  void hangup_shared() override {
+    CHECK(get_link_token() == 123);
+    Scheduler::instance()->finish();
+    stop();
+  }
+
+ private:
+  int cnt_;
+  ActorId<LinkTokenSlave> child_;
+};
+
+TEST(Actors, link_token) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR));
+  ConcurrentScheduler scheduler;
+  scheduler.init(0);
+  auto cnt = 100000;
+  scheduler.create_actor_unsafe<LinkTokenMasterActor>(0, "A", cnt).release();
+  scheduler.start();
+  while (scheduler.run_main(10)) {
+  }
+  scheduler.finish();
+}
+
+TEST(Actors, promise) {
+  int value = -1;
+  Promise<int> p1 = PromiseCreator::lambda([&](int x) { value = x; });
+  p1.set_error(Status::Error("Test error"));
+  ASSERT_EQ(0, value);
+  Promise<int32> p2 = PromiseCreator::lambda([&](Result<int32> x) { value = 1; });
+  p2.set_error(Status::Error("Test error"));
+  ASSERT_EQ(1, value);
+}
+
+class LaterSlave : public Actor {
+ public:
+  explicit LaterSlave(ActorShared<> parent) : parent_(std::move(parent)) {
+  }
+
+ private:
+  ActorShared<> parent_;
+
+  void hangup() override {
+    sb << "A";
+    send_closure(actor_id(this), &LaterSlave::finish);
+  }
+  void finish() {
+    sb << "B";
+    stop();
+  }
+};
+
+class LaterMasterActor : public Actor {
+  int cnt_ = 3;
+  std::vector<ActorOwn<LaterSlave>> children_;
+  void start_up() override {
+    for (int i = 0; i < cnt_; i++) {
+      children_.push_back(create_actor<LaterSlave>("B", actor_shared()));
+    }
+    yield();
+  }
+  void loop() override {
+    children_.clear();
+  }
+  void hangup_shared() override {
+    if (!--cnt_) {
+      Scheduler::instance()->finish();
+      stop();
+    }
+  }
+};
+
+TEST(Actors, later) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR));
+  sb.clear();
+  ConcurrentScheduler scheduler;
+  scheduler.init(0);
+  scheduler.create_actor_unsafe<LaterMasterActor>(0, "A").release();
+  scheduler.start();
+  while (scheduler.run_main(10)) {
+  }
+  scheduler.finish();
+  ASSERT_STREQ(sb.as_cslice().c_str(), "AAABBB");
+}
+
+class MultiPromise2 : public Actor {
+ public:
+  void start_up() override {
+    auto promise = PromiseCreator::lambda([](Result<Unit> result) {
+      result.ensure();
+      Scheduler::instance()->finish();
+    });
+
+    MultiPromiseActorSafe multi_promise;
+    multi_promise.add_promise(std::move(promise));
+    for (int i = 0; i < 10; i++) {
+      create_actor<SleepActor>("Sleep", 0.1, multi_promise.get_promise()).release();
+    }
+  }
+};
+
+class MultiPromise1 : public Actor {
+ public:
+  void start_up() override {
+    auto promise = PromiseCreator::lambda([](Result<Unit> result) {
+      CHECK(result.is_error());
+      create_actor<MultiPromise2>("B").release();
+    });
+    MultiPromiseActorSafe multi_promise;
+    multi_promise.add_promise(std::move(promise));
+  }
+};
+
+TEST(Actors, MultiPromise) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR));
+  sb.clear();
+  ConcurrentScheduler scheduler;
+  scheduler.init(0);
+  scheduler.create_actor_unsafe<MultiPromise1>(0, "A").release();
+  scheduler.start();
+  while (scheduler.run_main(10)) {
+  }
+  scheduler.finish();
+}
+
+class FastPromise : public Actor {
+ public:
+  void start_up() override {
+    PromiseFuture<int> pf;
+    auto promise = pf.move_promise();
+    auto future = pf.move_future();
+    promise.set_value(123);
+    CHECK(future.move_as_ok() == 123);
+    Scheduler::instance()->finish();
+  }
+};
+
+TEST(Actors, FastPromise) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR));
+  sb.clear();
+  ConcurrentScheduler scheduler;
+  scheduler.init(0);
+  scheduler.create_actor_unsafe<FastPromise>(0, "A").release();
+  scheduler.start();
+  while (scheduler.run_main(10)) {
+  }
+  scheduler.finish();
+}
+
+class StopInTeardown : public Actor {
+  void loop() override {
+    stop();
+  }
+  void tear_down() override {
+    stop();
+    Scheduler::instance()->finish();
+  }
+};
+
+TEST(Actors, stop_in_teardown) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR));
+  sb.clear();
+  ConcurrentScheduler scheduler;
+  scheduler.init(0);
+  scheduler.create_actor_unsafe<StopInTeardown>(0, "A").release();
+  scheduler.start();
+  while (scheduler.run_main(10)) {
+  }
+  scheduler.finish();
+}
+
+class AlwaysWaitForMailbox : public Actor {
+ public:
+  void start_up() override {
+    always_wait_for_mailbox();
+    create_actor<SleepActor>("Sleep", 0.1, PromiseCreator::lambda([actor_id = actor_id(this), ptr = this](Unit) {
+                               send_closure(actor_id, &AlwaysWaitForMailbox::g);
+                               send_closure(actor_id, &AlwaysWaitForMailbox::g);
+                               CHECK(!ptr->was_f_);
+                             }))
+        .release();
+  }
+
+  void f() {
+    was_f_ = true;
+    Scheduler::instance()->finish();
+  }
+  void g() {
+    send_closure(actor_id(this), &AlwaysWaitForMailbox::f);
+  }
+
+ private:
+  Timeout timeout_;
+  bool was_f_{false};
+};
+
+TEST(Actors, always_wait_for_mailbox) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR));
+  ConcurrentScheduler scheduler;
+  scheduler.init(0);
+  scheduler.create_actor_unsafe<AlwaysWaitForMailbox>(0, "A").release();
+  scheduler.start();
+  while (scheduler.run_main(10)) {
+  }
+  scheduler.finish();
+}
diff --git a/libs/tdlib/td/tdactor/test/actors_workers.cpp b/libs/tdlib/td/tdactor/test/actors_workers.cpp
new file mode 100644
index 0000000000..b97a258a44
--- /dev/null
+++ b/libs/tdlib/td/tdactor/test/actors_workers.cpp
@@ -0,0 +1,156 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/tests.h"
+
+#include "td/actor/actor.h"
+
+#include "td/utils/logging.h"
+
+REGISTER_TESTS(actors_workers);
+
+namespace {
+
+using namespace td;
+
+class PowerWorker final : public Actor {
+ public:
+  class Callback {
+   public:
+    Callback() = default;
+    Callback(const Callback &) = delete;
+    Callback &operator=(const Callback &) = delete;
+    Callback(Callback &&) = delete;
+    Callback &operator=(Callback &&) = delete;
+    virtual ~Callback() = default;
+    virtual void on_ready(int query, int res) = 0;
+    virtual void on_closed() = 0;
+  };
+  void set_callback(unique_ptr<Callback> callback) {
+    callback_ = std::move(callback);
+  }
+  void task(uint32 x, uint32 p) {
+    uint32 res = 1;
+    for (uint32 i = 0; i < p; i++) {
+      res *= x;
+    }
+    callback_->on_ready(x, res);
+  }
+  void close() {
+    callback_->on_closed();
+    stop();
+  }
+
+ private:
+  std::unique_ptr<Callback> callback_;
+};
+
+class Manager final : public Actor {
+ public:
+  Manager(int queries_n, int query_size, std::vector<ActorId<PowerWorker>> workers)
+      : workers_(std::move(workers)), left_query_(queries_n), query_size_(query_size) {
+  }
+
+  class Callback : public PowerWorker::Callback {
+   public:
+    Callback(ActorId<Manager> actor_id, int worker_id) : actor_id_(actor_id), worker_id_(worker_id) {
+    }
+    void on_ready(int query, int result) override {
+      send_closure(actor_id_, &Manager::on_ready, worker_id_, query, result);
+    }
+    void on_closed() override {
+      send_closure_later(actor_id_, &Manager::on_closed, worker_id_);
+    }
+
+   private:
+    ActorId<Manager> actor_id_;
+    int worker_id_;
+  };
+
+  void start_up() override {
+    ref_cnt_ = static_cast<int>(workers_.size());
+    int i = 0;
+    for (auto &worker : workers_) {
+      ref_cnt_++;
+      send_closure_later(worker, &PowerWorker::set_callback, make_unique<Callback>(actor_id(this), i));
+      i++;
+      send_closure_later(worker, &PowerWorker::task, 3, query_size_);
+      left_query_--;
+    }
+  }
+
+  void on_ready(int worker_id, int query, int res) {
+    ref_cnt_--;
+    if (left_query_ == 0) {
+      send_closure(workers_[worker_id], &PowerWorker::close);
+    } else {
+      ref_cnt_++;
+      send_closure(workers_[worker_id], &PowerWorker::task, 3, query_size_);
+      left_query_--;
+    }
+  }
+
+  void on_closed(int worker_id) {
+    ref_cnt_--;
+    if (ref_cnt_ == 0) {
+      Scheduler::instance()->finish();
+      stop();
+    }
+  }
+
+ private:
+  std::vector<ActorId<PowerWorker>> workers_;
+  int left_query_;
+  int ref_cnt_;
+  int query_size_;
+};
+
+void test_workers(int threads_n, int workers_n, int queries_n, int query_size) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(DEBUG));
+
+  ConcurrentScheduler sched;
+  sched.init(threads_n);
+
+  std::vector<ActorId<PowerWorker>> workers;
+  for (int i = 0; i < workers_n; i++) {
+    int thread_id = threads_n ? i % (threads_n - 1) + 2 : 0;
+    workers.push_back(sched.create_actor_unsafe<PowerWorker>(thread_id, "worker" + to_string(i)).release());
+  }
+  sched.create_actor_unsafe<Manager>(threads_n ? 1 : 0, "manager", queries_n, query_size, std::move(workers)).release();
+
+  sched.start();
+  while (sched.run_main(10)) {
+    // empty
+  }
+  sched.finish();
+
+  // sched.test_one_thread_run();
+}
+}  // namespace
+
+TEST(Actors, workers_big_query_one_thread) {
+  test_workers(0, 10, 1000, 300000);
+}
+
+TEST(Actors, workers_big_query_two_threads) {
+  test_workers(2, 10, 1000, 300000);
+}
+
+TEST(Actors, workers_big_query_nine_threads) {
+  test_workers(9, 10, 1000, 300000);
+}
+
+TEST(Actors, workers_small_query_one_thread) {
+  test_workers(0, 10, 1000000, 1);
+}
+
+TEST(Actors, workers_small_query_two_threads) {
+  test_workers(2, 10, 1000000, 1);
+}
+
+TEST(Actors, workers_small_query_nine_threads) {
+  test_workers(9, 10, 1000000, 1);
+}
diff --git a/libs/tdlib/td/tdclientjson_export_list b/libs/tdlib/td/tdclientjson_export_list
new file mode 100644
index 0000000000..f1db3603c4
--- /dev/null
+++ b/libs/tdlib/td/tdclientjson_export_list
@@ -0,0 +1,9 @@
+_td_json_client_create
+_td_json_client_destroy
+_td_json_client_send
+_td_json_client_receive
+_td_json_client_execute
+_td_set_log_file_path
+_td_set_log_max_file_size
+_td_set_log_verbosity_level
+_td_set_log_fatal_error_callback
diff --git a/libs/tdlib/td/tddb/CMakeLists.txt b/libs/tdlib/td/tddb/CMakeLists.txt
new file mode 100644
index 0000000000..531dcc5c02
--- /dev/null
+++ b/libs/tdlib/td/tddb/CMakeLists.txt
@@ -0,0 +1,55 @@
+cmake_minimum_required(VERSION 3.0.2 FATAL_ERROR)
+
+#SOURCE SETS
+set(TDDB_SOURCE
+  td/db/binlog/Binlog.cpp
+  td/db/binlog/BinlogEvent.cpp
+  td/db/binlog/ConcurrentBinlog.cpp
+  td/db/binlog/detail/BinlogEventsBuffer.cpp
+  td/db/binlog/detail/BinlogEventsProcessor.cpp
+
+  td/db/SqliteDb.cpp
+  td/db/SqliteStatement.cpp
+  td/db/SqliteKeyValueAsync.cpp
+
+  td/db/detail/RawSqliteDb.cpp
+
+  td/db/binlog/Binlog.h
+  td/db/binlog/BinlogInterface.h
+  td/db/binlog/BinlogEvent.h
+  td/db/binlog/BinlogHelper.h
+  td/db/binlog/ConcurrentBinlog.h
+  td/db/binlog/detail/BinlogEventsBuffer.h
+  td/db/binlog/detail/BinlogEventsProcessor.h
+
+  td/db/BinlogKeyValue.h
+  td/db/DbKey.h
+  td/db/KeyValueSyncInterface.h
+  td/db/Pmc.h
+  td/db/SeqKeyValue.h
+  td/db/SqliteConnectionSafe.h
+  td/db/SqliteDb.h
+  td/db/SqliteKeyValue.h
+  td/db/SqliteKeyValueAsync.h
+  td/db/SqliteKeyValueSafe.h
+  td/db/SqliteStatement.h
+  td/db/TsSeqKeyValue.h
+
+  td/db/detail/RawSqliteDb.h
+)
+
+add_library(tddb STATIC ${TDDB_SOURCE})
+target_include_directories(tddb PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>)
+target_link_libraries(tddb PUBLIC tdactor tdutils PRIVATE tdsqlite)
+
+if (NOT CMAKE_CROSSCOMPILING)
+  add_executable(binlog_dump td/db/binlog/binlog_dump.cpp)
+  target_link_libraries(binlog_dump PRIVATE tddb)
+endif()
+
+install(TARGETS tddb EXPORT TdTargets
+  LIBRARY DESTINATION lib
+  ARCHIVE DESTINATION lib
+  RUNTIME DESTINATION bin
+  INCLUDES DESTINATION include
+)
diff --git a/libs/tdlib/td/tddb/td/db/BinlogKeyValue.h b/libs/tdlib/td/tddb/td/db/BinlogKeyValue.h
new file mode 100644
index 0000000000..04df413d53
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/BinlogKeyValue.h
@@ -0,0 +1,252 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/db/binlog/Binlog.h"
+#include "td/db/binlog/BinlogEvent.h"
+#include "td/db/binlog/ConcurrentBinlog.h"
+#include "td/db/KeyValueSyncInterface.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/RwMutex.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/tl_parsers.h"
+#include "td/utils/tl_storers.h"
+
+#include <map>
+#include <memory>
+#include <unordered_map>
+#include <utility>
+
+namespace td {
+template <class BinlogT>
+class BinlogKeyValue : public KeyValueSyncInterface {
+ public:
+  static constexpr int32 magic = 0x2a280000;
+
+  struct Event : public Storer {
+    Event() = default;
+    Event(Slice key, Slice value) : key(key), value(value) {
+    }
+    Slice key;
+    Slice value;
+    template <class StorerT>
+    void store(StorerT &&storer) const {
+      storer.store_string(key);
+      storer.store_string(value);
+    }
+
+    template <class ParserT>
+    void parse(ParserT &&parser) {
+      key = parser.template fetch_string<Slice>();
+      value = parser.template fetch_string<Slice>();
+    }
+
+    size_t size() const override {
+      TlStorerCalcLength storer;
+      store(storer);
+      return storer.get_length();
+    }
+    size_t store(uint8 *ptr_x) const override {
+      auto ptr = reinterpret_cast<char *>(ptr_x);
+      TlStorerUnsafe storer(ptr);
+      store(storer);
+      return storer.get_buf() - ptr;
+    }
+  };
+
+  int32 get_magic() const {
+    return magic_;
+  }
+
+  Status init(string name, DbKey db_key = DbKey::empty(), int scheduler_id = -1,
+              int32 override_magic = 0) TD_WARN_UNUSED_RESULT {
+    close();
+    if (override_magic) {
+      magic_ = override_magic;
+    }
+
+    binlog_ = std::make_unique<BinlogT>();
+    TRY_STATUS(binlog_->init(name,
+                             [&](const BinlogEvent &binlog_event) {
+                               Event event;
+                               event.parse(TlParser(binlog_event.data_));
+                               map_.emplace(std::make_pair(event.key.str(),
+                                                           std::make_pair(event.value.str(), binlog_event.id_)));
+                             },
+                             std::move(db_key), DbKey::empty(), scheduler_id));
+    return Status::OK();
+  }
+
+  void external_init_begin(int32 override_magic = 0) {
+    close();
+    if (override_magic) {
+      magic_ = override_magic;
+    }
+  }
+
+  template <class OtherBinlogT>
+  void external_init_handle(BinlogKeyValue<OtherBinlogT> &&other) {
+    map_ = std::move(other.map_);
+  }
+
+  void external_init_handle(const BinlogEvent &binlog_event) {
+    Event event;
+    event.parse(TlParser(binlog_event.data_));
+    map_.emplace(std::make_pair(event.key.str(), std::make_pair(event.value.str(), binlog_event.id_)));
+  }
+
+  void external_init_finish(std::shared_ptr<BinlogT> binlog) {
+    binlog_ = std::move(binlog);
+  }
+
+  void close() {
+    *this = BinlogKeyValue();
+  }
+
+  SeqNo set(string key, string value) override {
+    auto lock = rw_mutex_.lock_write().move_as_ok();
+    uint64 old_id = 0;
+    auto it_ok = map_.insert({key, {value, 0}});
+    if (!it_ok.second) {
+      if (it_ok.first->second.first == value) {
+        return 0;
+      }
+      old_id = it_ok.first->second.second;
+      it_ok.first->second.first = value;
+    }
+    bool rewrite = false;
+    uint64 id;
+    auto seq_no = binlog_->next_id();
+    if (old_id != 0) {
+      rewrite = true;
+      id = old_id;
+    } else {
+      id = seq_no;
+      it_ok.first->second.second = id;
+    }
+
+    lock.reset();
+    add_event(seq_no,
+              BinlogEvent::create_raw(id, magic_, rewrite ? BinlogEvent::Flags::Rewrite : 0, Event{key, value}));
+    return seq_no;
+  }
+
+  SeqNo erase(const string &key) override {
+    auto lock = rw_mutex_.lock_write().move_as_ok();
+    auto it = map_.find(key);
+    if (it == map_.end()) {
+      return 0;
+    }
+    uint64 id = it->second.second;
+    map_.erase(it);
+    // LOG(ERROR) << "ADD EVENT";
+    auto seq_no = binlog_->next_id();
+    lock.reset();
+    add_event(seq_no, BinlogEvent::create_raw(id, BinlogEvent::ServiceTypes::Empty, BinlogEvent::Flags::Rewrite,
+                                              EmptyStorer()));
+    return seq_no;
+  }
+
+  void add_event(uint64 seq_no, BufferSlice &&event) {
+    binlog_->add_raw_event(seq_no, std::move(event));
+  }
+
+  bool isset(const string &key) override {
+    auto lock = rw_mutex_.lock_read().move_as_ok();
+    return map_.count(key) > 0;
+  }
+
+  string get(const string &key) override {
+    auto lock = rw_mutex_.lock_read().move_as_ok();
+    auto it = map_.find(key);
+    if (it == map_.end()) {
+      return string();
+    }
+    return it->second.first;
+  }
+
+  void force_sync(Promise<> &&promise) {
+    binlog_->force_sync(std::move(promise));
+  }
+  void lazy_sync(Promise<> &&promise) {
+    binlog_->lazy_sync(std::move(promise));
+  }
+
+  std::unordered_map<string, string> prefix_get(Slice prefix) {
+    // TODO: optimize with std::map?
+    auto lock = rw_mutex_.lock_write().move_as_ok();
+    std::unordered_map<string, string> res;
+    for (const auto &kv : map_) {
+      if (begins_with(kv.first, prefix)) {
+        res[kv.first] = kv.second.first;
+      }
+    }
+    return res;
+  }
+
+  std::unordered_map<string, string> get_all() {
+    auto lock = rw_mutex_.lock_write().move_as_ok();
+    std::unordered_map<string, string> res;
+    for (const auto &kv : map_) {
+      res[kv.first] = kv.second.first;
+    }
+    return res;
+  }
+
+  void erase_by_prefix(Slice prefix) {
+    auto lock = rw_mutex_.lock_write().move_as_ok();
+    std::vector<uint64> ids;
+    for (auto it = map_.begin(); it != map_.end();) {
+      if (begins_with(it->first, prefix)) {
+        ids.push_back(it->second.second);
+        it = map_.erase(it);
+      } else {
+        ++it;
+      }
+    }
+    auto seq_no = binlog_->next_id(narrow_cast<int32>(ids.size()));
+    lock.reset();
+    for (auto id : ids) {
+      add_event(seq_no, BinlogEvent::create_raw(id, BinlogEvent::ServiceTypes::Empty, BinlogEvent::Flags::Rewrite,
+                                                EmptyStorer()));
+      seq_no++;
+    }
+  }
+  template <class T>
+  friend class BinlogKeyValue;
+
+  static Status destroy(Slice name) {
+    return Binlog::destroy(name);
+  }
+
+ private:
+  std::unordered_map<string, std::pair<string, uint64>> map_;
+  std::shared_ptr<BinlogT> binlog_;
+  RwMutex rw_mutex_;
+  int32 magic_ = magic;
+};
+template <>
+inline void BinlogKeyValue<Binlog>::add_event(uint64 seq_no, BufferSlice &&event) {
+  binlog_->add_raw_event(std::move(event));
+}
+template <>
+inline void BinlogKeyValue<Binlog>::force_sync(Promise<> &&promise) {
+  binlog_->sync();
+  promise.set_value(Unit());
+}
+template <>
+inline void BinlogKeyValue<Binlog>::lazy_sync(Promise<> &&promise) {
+  force_sync(std::move(promise));
+}
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/DbKey.h b/libs/tdlib/td/tddb/td/db/DbKey.h
new file mode 100644
index 0000000000..b0edde2ae1
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/DbKey.h
@@ -0,0 +1,51 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+
+namespace td {
+class DbKey {
+ public:
+  enum Type { Empty, RawKey, Password };
+
+  Type type() const {
+    return type_;
+  }
+  bool is_empty() const {
+    return type_ == Empty;
+  }
+  bool is_raw_key() const {
+    return type_ == RawKey;
+  }
+  bool is_password() const {
+    return type_ == Password;
+  }
+  CSlice data() const {
+    return data_;
+  }
+  static DbKey raw_key(string raw_key) {
+    DbKey res;
+    res.type_ = RawKey;
+    res.data_ = std::move(raw_key);
+    return res;
+  }
+  static DbKey password(string password) {
+    DbKey res;
+    res.type_ = Password;
+    res.data_ = std::move(password);
+    return res;
+  }
+  static DbKey empty() {
+    return DbKey();
+  }
+
+ private:
+  Type type_{Empty};
+  string data_;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/KeyValueSyncInterface.h b/libs/tdlib/td/tddb/td/db/KeyValueSyncInterface.h
new file mode 100644
index 0000000000..8d19d0e75c
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/KeyValueSyncInterface.h
@@ -0,0 +1,35 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+namespace td {
+
+class KeyValueSyncInterface {
+ public:
+  // SeqNo is used to restore total order on all write queries.
+  // Some implementations may return 0 as SeqNo.
+  using SeqNo = uint64;
+
+  KeyValueSyncInterface() = default;
+  KeyValueSyncInterface(const KeyValueSyncInterface &) = delete;
+  KeyValueSyncInterface &operator=(const KeyValueSyncInterface &) = delete;
+  KeyValueSyncInterface(KeyValueSyncInterface &&) = default;
+  KeyValueSyncInterface &operator=(KeyValueSyncInterface &&) = default;
+  virtual ~KeyValueSyncInterface() = default;
+
+  virtual SeqNo set(string key, string value) = 0;
+
+  virtual bool isset(const string &key) = 0;
+
+  virtual string get(const string &key) = 0;
+
+  virtual SeqNo erase(const string &key) = 0;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/Pmc.h b/libs/tdlib/td/tddb/td/db/Pmc.h
new file mode 100644
index 0000000000..dcf0e0c351
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/Pmc.h
@@ -0,0 +1,27 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/db/binlog/ConcurrentBinlog.h"
+#include "td/db/BinlogKeyValue.h"
+#include "td/db/SqliteKeyValue.h"
+
+#include "td/utils/common.h"
+
+#include <memory>
+
+namespace td {
+
+using BinlogPmcBase = BinlogKeyValue<ConcurrentBinlog>;
+using BinlogPmc = std::shared_ptr<BinlogPmcBase>;
+using BinlogPmcPtr = BinlogPmcBase *;
+
+using BigPmcBase = SqliteKeyValue;
+using BigPmc = std::unique_ptr<BigPmcBase>;
+using BigPmcPtr = BigPmcBase *;
+
+};  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/SeqKeyValue.h b/libs/tdlib/td/tddb/td/db/SeqKeyValue.h
new file mode 100644
index 0000000000..ec6f2b99b6
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/SeqKeyValue.h
@@ -0,0 +1,78 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/Slice.h"
+
+#include <unordered_map>
+
+namespace td {
+class SeqKeyValue {
+ public:
+  using SeqNo = uint64;
+  SeqKeyValue() = default;
+  SeqKeyValue(SeqKeyValue &&) = default;
+  SeqKeyValue &operator=(SeqKeyValue &&) = default;
+  SeqKeyValue(const SeqKeyValue &) = delete;
+  SeqKeyValue &operator=(const SeqKeyValue &) = delete;
+  ~SeqKeyValue() = default;
+
+  SeqNo set(Slice key, Slice value) {
+    auto it_ok = map_.insert({key.str(), value.str()});
+    if (!it_ok.second) {
+      if (it_ok.first->second == value) {
+        return 0;
+      }
+      it_ok.first->second = value.str();
+    }
+    return next_seq_no();
+  }
+  SeqNo erase(const string &key) {
+    auto it = map_.find(key);
+    if (it == map_.end()) {
+      return 0;
+    }
+    map_.erase(it);
+    return next_seq_no();
+  }
+  SeqNo seq_no() const {
+    return current_id_ + 1;
+  }
+  string get(const string &key) const {
+    auto it = map_.find(key);
+    if (it == map_.end()) {
+      return string();
+    }
+    return it->second;
+  }
+
+  template <class F>
+  void foreach (const F &f) {
+    for (auto &it : map_) {
+      f(it.first, it.second);
+    }
+  }
+
+  size_t size() const {
+    return map_.size();
+  }
+
+  void reset_seq_no() {
+    current_id_ = 0;
+  }
+  std::unordered_map<string, string> get_all() const {
+    return map_;
+  }
+
+ private:
+  std::unordered_map<string, string> map_;
+  SeqNo current_id_ = 0;
+  SeqNo next_seq_no() {
+    return ++current_id_;
+  }
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/SqliteConnectionSafe.h b/libs/tdlib/td/tddb/td/db/SqliteConnectionSafe.h
new file mode 100644
index 0000000000..6e45e79e63
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/SqliteConnectionSafe.h
@@ -0,0 +1,53 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/SchedulerLocalStorage.h"
+
+#include "td/db/SqliteDb.h"
+
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+
+namespace td {
+
+class SqliteConnectionSafe {
+ public:
+  SqliteConnectionSafe() = default;
+  explicit SqliteConnectionSafe(string name, DbKey key = DbKey::empty())
+      : lsls_connection_([name = name, key = std::move(key)] {
+        auto db = SqliteDb::open_with_key(name, key).move_as_ok();
+        db.exec("PRAGMA synchronous=NORMAL").ensure();
+        db.exec("PRAGMA temp_store=MEMORY").ensure();
+        db.exec("PRAGMA secure_delete=1").ensure();
+        db.exec("PRAGMA recursive_triggers=1").ensure();
+        return db;
+      })
+      , name_(std::move(name)) {
+  }
+
+  SqliteDb &get() {
+    return lsls_connection_.get();
+  }
+
+  void close() {
+    LOG(INFO) << "Close sqlite db " << tag("path", name_);
+    lsls_connection_.clear_values();
+  }
+  void close_and_destroy() {
+    close();
+    LOG(INFO) << "Destroy sqlite db " << tag("path", name_);
+    SqliteDb::destroy(name_).ignore();
+  }
+
+ private:
+  LazySchedulerLocalStorage<SqliteDb> lsls_connection_;
+  string name_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/SqliteDb.cpp b/libs/tdlib/td/tddb/td/db/SqliteDb.cpp
new file mode 100644
index 0000000000..819818197d
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/SqliteDb.cpp
@@ -0,0 +1,228 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/db/SqliteDb.h"
+
+#include "td/utils/format.h"
+#include "td/utils/port/path.h"
+#include "td/utils/port/Stat.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/Timer.h"
+
+#include "sqlite/sqlite3.h"
+
+namespace td {
+
+namespace {
+string db_key_to_sqlcipher_key(const DbKey &db_key) {
+  if (db_key.is_empty()) {
+    return "''";
+  }
+  if (db_key.is_password()) {
+    return PSTRING() << "'" << db_key.data().str() << "'";
+  }
+  CHECK(db_key.is_raw_key());
+  Slice raw_key = db_key.data();
+  CHECK(raw_key.size() == 32);
+  size_t expected_size = 64 + 5;
+  string res(expected_size + 50, ' ');
+  StringBuilder sb(res);
+  sb << '"';
+  sb << 'x';
+  sb << '\'';
+  sb << format::as_hex_dump<0>(raw_key);
+  sb << '\'';
+  sb << '"';
+  CHECK(!sb.is_error());
+  CHECK(sb.as_cslice().size() == expected_size);
+  res.resize(expected_size);
+  return res;
+}
+}  // namespace
+
+SqliteDb::~SqliteDb() = default;
+
+Status SqliteDb::init(CSlice path, bool *was_created) {
+  // If database does not exist, delete all other files which may left
+  // from older database
+  bool is_db_exists = stat(path).is_ok();
+  if (!is_db_exists) {
+    destroy(path).ignore();
+  }
+
+  if (was_created != nullptr) {
+    *was_created = !is_db_exists;
+  }
+  sqlite3 *db;
+  CHECK(sqlite3_threadsafe() != 0);
+  int rc = sqlite3_open_v2(path.c_str(), &db, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE /*| SQLITE_OPEN_SHAREDCACHE*/,
+                           nullptr);
+  if (rc != SQLITE_OK) {
+    auto res = Status::Error(PSLICE() << "Failed to open db: " << detail::RawSqliteDb::last_error(db));
+    sqlite3_close(db);
+    return res;
+  }
+  sqlite3_busy_timeout(db, 1000 * 5 /* 5 seconds */);
+  raw_ = std::make_shared<detail::RawSqliteDb>(db, path.str());
+  return Status::OK();
+}
+
+static void trace_callback(void *ptr, const char *query) {
+  LOG(ERROR) << query;
+}
+static int trace_v2_callback(unsigned code, void *ctx, void *p_raw, void *x_raw) {
+  CHECK(code == SQLITE_TRACE_STMT);
+  auto x = static_cast<const char *>(x_raw);
+  if (x[0] == '-' && x[1] == '-') {
+    trace_callback(ctx, x);
+  } else {
+    trace_callback(ctx, sqlite3_expanded_sql(static_cast<sqlite3_stmt *>(p_raw)));
+  }
+
+  return 0;
+}
+void SqliteDb::trace(bool flag) {
+  sqlite3_trace_v2(raw_->db(), SQLITE_TRACE_STMT, flag ? trace_v2_callback : nullptr, nullptr);
+}
+
+Status SqliteDb::exec(CSlice cmd) {
+  CHECK(!empty());
+  char *msg;
+  VLOG(sqlite) << "Start exec " << tag("cmd", cmd) << tag("db", raw_->db());
+  auto rc = sqlite3_exec(raw_->db(), cmd.c_str(), nullptr, nullptr, &msg);
+  VLOG(sqlite) << "Finish exec " << tag("cmd", cmd) << tag("db", raw_->db());
+  if (rc != SQLITE_OK) {
+    CHECK(msg != nullptr);
+    return Status::Error(PSLICE() << tag("query", cmd) << " failed: " << msg);
+  }
+  CHECK(msg == nullptr);
+  return Status::OK();
+}
+
+Result<bool> SqliteDb::has_table(Slice table) {
+  TRY_RESULT(stmt, get_statement(PSLICE() << "SELECT count(*) FROM sqlite_master WHERE type='table' AND name='" << table
+                                          << "'"));
+  TRY_STATUS(stmt.step());
+  CHECK(stmt.has_row());
+  auto cnt = stmt.view_int32(0);
+  return cnt == 1;
+}
+Result<string> SqliteDb::get_pragma(Slice name) {
+  TRY_RESULT(stmt, get_statement(PSLICE() << "PRAGMA " << name));
+  TRY_STATUS(stmt.step());
+  CHECK(stmt.has_row());
+  auto res = stmt.view_blob(0).str();
+  TRY_STATUS(stmt.step());
+  CHECK(!stmt.can_step());
+  return std::move(res);
+}
+
+Result<int32> SqliteDb::user_version() {
+  TRY_RESULT(get_version_stmt, get_statement("PRAGMA user_version"));
+  TRY_STATUS(get_version_stmt.step());
+  if (!get_version_stmt.has_row()) {
+    return Status::Error("PRAGMA user_version failed");
+  }
+  return get_version_stmt.view_int32(0);
+}
+
+Status SqliteDb::set_user_version(int32 version) {
+  return exec(PSLICE() << "PRAGMA user_version = " << version);
+}
+
+Status SqliteDb::begin_transaction() {
+  return exec("BEGIN");
+}
+Status SqliteDb::commit_transaction() {
+  return exec("COMMIT");
+}
+
+bool SqliteDb::is_encrypted() {
+  return exec("SELECT count(*) FROM sqlite_master").is_error();
+}
+
+Result<SqliteDb> SqliteDb::open_with_key(CSlice path, const DbKey &db_key) {
+  SqliteDb db;
+  TRY_STATUS(db.init(path));
+  if (!db_key.is_empty()) {
+    if (!db.is_encrypted()) {
+      return Status::Error("No key is needed");
+    }
+    auto key = db_key_to_sqlcipher_key(db_key);
+    TRY_STATUS(db.exec(PSLICE() << "PRAGMA key = " << key));
+  }
+  if (db.is_encrypted()) {
+    return Status::Error("Wrong key");
+  }
+  return std::move(db);
+}
+
+Status SqliteDb::change_key(CSlice path, const DbKey &new_db_key, const DbKey &old_db_key) {
+  // fast path
+  {
+    auto r_db = open_with_key(path, new_db_key);
+    if (r_db.is_ok()) {
+      return Status::OK();
+    }
+  }
+
+  TRY_RESULT(db, open_with_key(path, old_db_key));
+  TRY_RESULT(user_version, db.user_version());
+  auto new_key = db_key_to_sqlcipher_key(new_db_key);
+  if (old_db_key.is_empty() && !new_db_key.is_empty()) {
+    LOG(DEBUG) << "ENCRYPT";
+    // Encrypt
+    PerfWarningTimer timer("Encrypt sqlite database", 0.1);
+    auto tmp_path = path.str() + ".ecnrypted";
+    unlink(tmp_path).ignore();
+
+    // make shure that database is not empty
+    TRY_STATUS(db.exec("CREATE TABLE IF NOT EXISTS encryption_dummy_table(id INT PRIMARY KEY)"));
+    //NB: not really safe
+    TRY_STATUS(db.exec(PSLICE() << "ATTACH DATABASE '" << tmp_path << "' AS encrypted KEY " << new_key));
+    TRY_STATUS(db.exec("SELECT sqlcipher_export('encrypted')"));
+    TRY_STATUS(db.exec(PSLICE() << "PRAGMA encrypted.user_version = " << user_version));
+    TRY_STATUS(db.exec("DETACH DATABASE encrypted"));
+    db.close();
+    TRY_STATUS(rename(tmp_path, path));
+  } else if (!old_db_key.is_empty() && new_db_key.is_empty()) {
+    LOG(DEBUG) << "DECRYPT";
+    // Dectypt
+    PerfWarningTimer timer("Decrypt sqlite database", 0.1);
+    auto tmp_path = path.str() + ".ecnrypted";
+    unlink(tmp_path).ignore();
+
+    //NB: not really safe
+    TRY_STATUS(db.exec(PSLICE() << "ATTACH DATABASE '" << tmp_path << "' AS decrypted KEY ''"));
+    TRY_STATUS(db.exec("SELECT sqlcipher_export('decrypted')"));
+    TRY_STATUS(db.exec(PSLICE() << "PRAGMA decrypted.user_version = " << user_version));
+    TRY_STATUS(db.exec("DETACH DATABASE decrypted"));
+    db.close();
+    TRY_STATUS(rename(tmp_path, path));
+  } else {
+    LOG(DEBUG) << "REKEY";
+    PerfWarningTimer timer("Rekey sqlite database", 0.1);
+    TRY_STATUS(db.exec(PSLICE() << "PRAGMA rekey = " << new_key));
+  }
+
+  TRY_RESULT(new_db, open_with_key(path, new_db_key));
+  CHECK(new_db.user_version().ok() == user_version);
+  return Status::OK();
+}
+Status SqliteDb::destroy(Slice path) {
+  return detail::RawSqliteDb::destroy(path);
+}
+
+Result<SqliteStatement> SqliteDb::get_statement(CSlice statement) {
+  sqlite3_stmt *stmt = nullptr;
+  auto rc = sqlite3_prepare_v2(get_native(), statement.c_str(), static_cast<int>(statement.size()) + 1, &stmt, nullptr);
+  if (rc != SQLITE_OK) {
+    return Status::Error(PSLICE() << "Failed to prepare sqlite " << tag("stmt", statement) << raw_->last_error());
+  }
+  return SqliteStatement(stmt, raw_);
+}
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/SqliteDb.h b/libs/tdlib/td/tddb/td/db/SqliteDb.h
new file mode 100644
index 0000000000..40137464ce
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/SqliteDb.h
@@ -0,0 +1,86 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/db/DbKey.h"
+#include "td/db/SqliteStatement.h"
+
+#include "td/db/detail/RawSqliteDb.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <memory>
+
+struct sqlite3;
+
+namespace td {
+
+class SqliteDb {
+ public:
+  SqliteDb() = default;
+  explicit SqliteDb(CSlice path) {
+    auto status = init(path);
+    LOG_IF(FATAL, status.is_error()) << status;
+  }
+  SqliteDb(SqliteDb &&) = default;
+  SqliteDb &operator=(SqliteDb &&) = default;
+  SqliteDb(const SqliteDb &) = delete;
+  SqliteDb &operator=(const SqliteDb &) = delete;
+  ~SqliteDb();
+
+  // dangerous
+  SqliteDb clone() const {
+    return SqliteDb(raw_);
+  }
+
+  bool empty() const {
+    return !raw_;
+  }
+  void close() {
+    *this = SqliteDb();
+  }
+
+  Status init(CSlice path, bool *was_created = nullptr) TD_WARN_UNUSED_RESULT;
+  Status exec(CSlice cmd) TD_WARN_UNUSED_RESULT;
+  Result<bool> has_table(Slice table);
+  Result<string> get_pragma(Slice name);
+  Status begin_transaction();
+  Status commit_transaction();
+
+  Result<int32> user_version();
+  Status set_user_version(int32 version);
+  void trace(bool flag);
+
+  static Status destroy(Slice path) TD_WARN_UNUSED_RESULT;
+
+  // Anyway we can't change the key on the fly, so static functions is more than enough
+  static Result<SqliteDb> open_with_key(CSlice path, const DbKey &db_key);
+  static Status change_key(CSlice path, const DbKey &new_db_key, const DbKey &old_db_key);
+
+  Status last_error();
+
+  sqlite3 *get_native() const {
+    return raw_->db();
+  }
+
+  Result<SqliteStatement> get_statement(CSlice statement) TD_WARN_UNUSED_RESULT;
+
+  template <class F>
+  static void with_db_path(Slice main_path, F &&f) {
+    detail::RawSqliteDb::with_db_path(main_path, f);
+  }
+
+ private:
+  explicit SqliteDb(std::shared_ptr<detail::RawSqliteDb> raw) : raw_(std::move(raw)) {
+  }
+  std::shared_ptr<detail::RawSqliteDb> raw_;
+
+  bool is_encrypted();
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/SqliteKeyValue.h b/libs/tdlib/td/tddb/td/db/SqliteKeyValue.h
new file mode 100644
index 0000000000..6fe050e7f2
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/SqliteKeyValue.h
@@ -0,0 +1,221 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/db/SqliteDb.h"
+#include "td/db/SqliteStatement.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <unordered_map>
+
+namespace td {
+class SqliteKeyValue {
+ public:
+  static Status drop(SqliteDb &connection, Slice kv_name) TD_WARN_UNUSED_RESULT {
+    return connection.exec(PSLICE() << "DROP TABLE IF EXISTS " << kv_name);
+  }
+
+  static Status init(SqliteDb &connection, Slice kv_name) TD_WARN_UNUSED_RESULT {
+    return connection.exec(PSLICE() << "CREATE TABLE IF NOT EXISTS " << kv_name << " (k BLOB PRIMARY KEY, v BLOB)");
+  }
+
+  using SeqNo = uint64;
+  Result<bool> init(string name) TD_WARN_UNUSED_RESULT {
+    name_ = std::move(name);
+    bool is_created = false;
+    SqliteDb db;
+    TRY_STATUS(db.init(name, &is_created));
+    TRY_STATUS(db.exec("PRAGMA encoding=\"UTF-8\""));
+    TRY_STATUS(db.exec("PRAGMA synchronous=NORMAL"));
+    TRY_STATUS(db.exec("PRAGMA journal_mode=WAL"));
+    TRY_STATUS(db.exec("PRAGMA temp_store=MEMORY"));
+    TRY_STATUS(init_with_connection(std::move(db), "KV"));
+    return is_created;
+  }
+
+  Status init_with_connection(SqliteDb connection, string kv_name) {
+    db_ = std::move(connection);
+    kv_name_ = std::move(kv_name);
+    TRY_STATUS(init(db_, kv_name_));
+    TRY_STATUS(db_.exec(PSLICE() << "CREATE TABLE IF NOT EXISTS " << kv_name_ << " (k BLOB PRIMARY KEY, v BLOB)"));
+
+    TRY_RESULT(set_stmt, db_.get_statement(PSLICE() << "REPLACE INTO " << kv_name_ << " (k, v) VALUES (?1, ?2)"));
+    set_stmt_ = std::move(set_stmt);
+    TRY_RESULT(get_stmt, db_.get_statement(PSLICE() << "SELECT v FROM " << kv_name_ << " WHERE k = ?1"));
+    get_stmt_ = std::move(get_stmt);
+    TRY_RESULT(erase_stmt, db_.get_statement(PSLICE() << "DELETE FROM " << kv_name_ << " WHERE k = ?1"));
+    erase_stmt_ = std::move(erase_stmt);
+    TRY_RESULT(get_all_stmt, db_.get_statement(PSLICE() << "SELECT k, v FROM " << kv_name_ << ""));
+
+    TRY_RESULT(erase_by_prefix_stmt,
+               db_.get_statement(PSLICE() << "DELETE FROM " << kv_name_ << " WHERE ?1 <= k AND k < ?2"));
+    erase_by_prefix_stmt_ = std::move(erase_by_prefix_stmt);
+
+    TRY_RESULT(erase_by_prefix_rare_stmt,
+               db_.get_statement(PSLICE() << "DELETE FROM " << kv_name_ << " WHERE ?1 <= k"));
+    erase_by_prefix_rare_stmt_ = std::move(erase_by_prefix_rare_stmt);
+
+    TRY_RESULT(get_by_prefix_stmt,
+               db_.get_statement(PSLICE() << "SELECT k, v FROM " << kv_name_ << " WHERE ?1 <= k AND k < ?2"));
+    get_by_prefix_stmt_ = std::move(get_by_prefix_stmt);
+
+    TRY_RESULT(get_by_prefix_rare_stmt,
+               db_.get_statement(PSLICE() << "SELECT k, v FROM " << kv_name_ << " WHERE ?1 <= k"));
+    get_by_prefix_rare_stmt_ = std::move(get_by_prefix_rare_stmt);
+
+    get_all_stmt_ = std::move(get_all_stmt);
+    return Status::OK();
+  }
+
+  Result<bool> try_regenerate_index() TD_WARN_UNUSED_RESULT {
+    return false;
+  }
+  void close() {
+    clear();
+  }
+  void close_silent() {
+    clear();
+  }
+  static Status destroy(Slice name) {
+    return SqliteDb::destroy(name);
+  }
+  void close_and_destroy() {
+    db_.exec(PSLICE() << "DROP TABLE IF EXISTS " << kv_name_).ensure();
+    auto name = std::move(name_);
+    clear();
+    if (!name.empty()) {
+      SqliteDb::destroy(name).ignore();
+    }
+  }
+
+  SeqNo set(Slice key, Slice value) {
+    set_stmt_.bind_blob(1, key).ensure();
+    set_stmt_.bind_blob(2, value).ensure();
+    set_stmt_.step().ensure();
+    set_stmt_.reset();
+    return 0;
+  }
+
+  SeqNo erase(Slice key) {
+    erase_stmt_.bind_blob(1, key).ensure();
+    erase_stmt_.step().ensure();
+    erase_stmt_.reset();
+    return 0;
+  }
+  string get(Slice key) {
+    SCOPE_EXIT {
+      get_stmt_.reset();
+    };
+    get_stmt_.bind_blob(1, key).ensure();
+    get_stmt_.step().ensure();
+    if (!get_stmt_.has_row()) {
+      return "";
+    }
+    auto data = get_stmt_.view_blob(0).str();
+    get_stmt_.step().ignore();
+    return data;
+  }
+
+  Status begin_transaction() {
+    return db_.begin_transaction();
+  }
+  Status commit_transaction() {
+    return db_.commit_transaction();
+  }
+
+  void erase_by_prefix(Slice prefix) {
+    auto next = next_prefix(prefix);
+    if (next.empty()) {
+      SCOPE_EXIT {
+        erase_by_prefix_rare_stmt_.reset();
+      };
+      erase_by_prefix_rare_stmt_.bind_blob(1, prefix).ensure();
+      erase_by_prefix_rare_stmt_.step().ensure();
+    } else {
+      SCOPE_EXIT {
+        erase_by_prefix_stmt_.reset();
+      };
+      erase_by_prefix_stmt_.bind_blob(1, prefix).ensure();
+      erase_by_prefix_stmt_.bind_blob(2, next).ensure();
+      erase_by_prefix_stmt_.step().ensure();
+    }
+  };
+
+  std::unordered_map<string, string> get_all() {
+    std::unordered_map<string, string> res;
+    get_by_prefix("", [&](Slice key, Slice value) { res.emplace(key.str(), value.str()); });
+    return res;
+  }
+
+  template <class CallbackT>
+  void get_by_prefix(Slice prefix, CallbackT &&callback) {
+    string next;
+    if (!prefix.empty()) {
+      next = next_prefix(prefix);
+    }
+    get_by_range(prefix, next, callback);
+  }
+  template <class CallbackT>
+  void get_by_range(Slice from, Slice till, CallbackT &&callback) {
+    SqliteStatement *stmt = nullptr;
+    if (from.empty()) {
+      stmt = &get_all_stmt_;
+    } else {
+      if (till.empty()) {
+        stmt = &get_by_prefix_rare_stmt_;
+        stmt->bind_blob(1, till).ensure();
+      } else {
+        stmt = &get_by_prefix_stmt_;
+        stmt->bind_blob(1, from).ensure();
+        stmt->bind_blob(2, till).ensure();
+      }
+    }
+    auto guard = stmt->guard();
+    stmt->step().ensure();
+    while (stmt->has_row()) {
+      callback(stmt->view_blob(0), stmt->view_blob(1));
+      stmt->step().ensure();
+    }
+  }
+
+  void clear() {
+    *this = SqliteKeyValue();
+  }
+
+ private:
+  string name_;  // deprecated
+  string kv_name_;
+  SqliteDb db_;
+  SqliteStatement get_stmt_;
+  SqliteStatement set_stmt_;
+  SqliteStatement erase_stmt_;
+  SqliteStatement get_all_stmt_;
+  SqliteStatement erase_by_prefix_stmt_;
+  SqliteStatement erase_by_prefix_rare_stmt_;
+  SqliteStatement get_by_prefix_stmt_;
+  SqliteStatement get_by_prefix_rare_stmt_;
+
+  string next_prefix(Slice prefix) {
+    string next = prefix.str();
+    size_t pos = next.size();
+    while (pos) {
+      pos--;
+      auto value = static_cast<uint8>(next[pos]);
+      value++;
+      next[pos] = static_cast<char>(value);
+      if (value != 0) {
+        return next;
+      }
+    }
+    return string{};
+  }
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/SqliteKeyValueAsync.cpp b/libs/tdlib/td/tddb/td/db/SqliteKeyValueAsync.cpp
new file mode 100644
index 0000000000..e8575b62f1
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/SqliteKeyValueAsync.cpp
@@ -0,0 +1,141 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/db/SqliteKeyValueAsync.h"
+
+#include "td/utils/optional.h"
+#include "td/utils/Time.h"
+
+#include <unordered_map>
+
+namespace td {
+class SqliteKeyValueAsync : public SqliteKeyValueAsyncInterface {
+ public:
+  explicit SqliteKeyValueAsync(std::shared_ptr<SqliteKeyValueSafe> kv_safe, int32 scheduler_id = -1) {
+    impl_ = create_actor_on_scheduler<Impl>("KV", scheduler_id, std::move(kv_safe));
+  }
+  void set(string key, string value, Promise<> promise) override {
+    send_closure_later(impl_, &Impl::set, std::move(key), std::move(value), std::move(promise));
+  }
+  void erase(string key, Promise<> promise) override {
+    send_closure_later(impl_, &Impl::erase, std::move(key), std::move(promise));
+  }
+  void get(string key, Promise<string> promise) override {
+    send_closure_later(impl_, &Impl::get, std::move(key), std::move(promise));
+  }
+  void close(Promise<> promise) override {
+    send_closure_later(impl_, &Impl::close, std::move(promise));
+  }
+
+ private:
+  class Impl : public Actor {
+   public:
+    explicit Impl(std::shared_ptr<SqliteKeyValueSafe> kv_safe) : kv_safe_(std::move(kv_safe)) {
+    }
+    void set(string key, string value, Promise<> promise) {
+      auto it = buffer_.find(key);
+      if (it != buffer_.end()) {
+        it->second = std::move(value);
+      } else {
+        buffer_.emplace(std::move(key), std::move(value));
+      }
+      if (promise) {
+        buffer_promises_.push_back(std::move(promise));
+      }
+      cnt_++;
+      do_flush(false /*force*/);
+    }
+    void erase(string key, Promise<> promise) {
+      auto it = buffer_.find(key);
+      if (it != buffer_.end()) {
+        it->second = optional<string>();
+      } else {
+        buffer_.emplace(std::move(key), optional<string>());
+      }
+      if (promise) {
+        buffer_promises_.push_back(std::move(promise));
+      }
+      cnt_++;
+      do_flush(false /*force*/);
+    }
+
+    void get(const string &key, Promise<string> promise) {
+      auto it = buffer_.find(key);
+      if (it != buffer_.end()) {
+        return promise.set_value(it->second ? it->second.value() : "");
+      }
+      promise.set_value(kv_->get(key));
+    }
+    void close(Promise<> promise) {
+      do_flush(true /*force*/);
+      kv_safe_.reset();
+      kv_ = nullptr;
+      stop();
+      promise.set_value(Unit());
+    }
+
+   private:
+    std::shared_ptr<SqliteKeyValueSafe> kv_safe_;
+    SqliteKeyValue *kv_ = nullptr;
+
+    static constexpr double MAX_PENDING_QUERIES_DELAY = 1;
+    static constexpr size_t MAX_PENDING_QUERIES_COUNT = 100;
+    std::unordered_map<string, optional<string>> buffer_;
+    std::vector<Promise<>> buffer_promises_;
+    size_t cnt_ = 0;
+
+    double wakeup_at_ = 0;
+    void do_flush(bool force) {
+      if (buffer_.empty()) {
+        return;
+      }
+
+      if (!force) {
+        auto now = Time::now_cached();
+        if (wakeup_at_ == 0) {
+          wakeup_at_ = now + MAX_PENDING_QUERIES_DELAY;
+        }
+        if (now < wakeup_at_ && cnt_ < MAX_PENDING_QUERIES_COUNT) {
+          set_timeout_at(wakeup_at_);
+          return;
+        }
+      }
+
+      wakeup_at_ = 0;
+      cnt_ = 0;
+
+      kv_->begin_transaction().ensure();
+      for (auto &it : buffer_) {
+        if (it.second) {
+          kv_->set(it.first, it.second.value());
+        } else {
+          kv_->erase(it.first);
+        }
+      }
+      kv_->commit_transaction().ensure();
+      buffer_.clear();
+      for (auto &promise : buffer_promises_) {
+        promise.set_value(Unit());
+      }
+      buffer_promises_.clear();
+    }
+
+    void timeout_expired() override {
+      do_flush(false /*force*/);
+    }
+
+    void start_up() override {
+      kv_ = &kv_safe_->get();
+    }
+  };
+  ActorOwn<Impl> impl_;
+};
+std::unique_ptr<SqliteKeyValueAsyncInterface> create_sqlite_key_value_async(std::shared_ptr<SqliteKeyValueSafe> kv,
+                                                                            int32 scheduler_id) {
+  return std::make_unique<SqliteKeyValueAsync>(std::move(kv), scheduler_id);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/SqliteKeyValueAsync.h b/libs/tdlib/td/tddb/td/db/SqliteKeyValueAsync.h
new file mode 100644
index 0000000000..6015d26fb2
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/SqliteKeyValueAsync.h
@@ -0,0 +1,30 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/db/SqliteKeyValueSafe.h"
+
+#include "td/actor/PromiseFuture.h"
+
+#include <memory>
+
+namespace td {
+
+class SqliteKeyValueAsyncInterface {
+ public:
+  virtual ~SqliteKeyValueAsyncInterface() = default;
+
+  virtual void set(string key, string value, Promise<> promise) = 0;
+  virtual void erase(string key, Promise<> promise) = 0;
+
+  virtual void get(string key, Promise<string> promise) = 0;
+  virtual void close(Promise<> promise) = 0;
+};
+
+std::unique_ptr<SqliteKeyValueAsyncInterface> create_sqlite_key_value_async(std::shared_ptr<SqliteKeyValueSafe> kv,
+                                                                            int32 scheduler_id = 1);
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/SqliteKeyValueSafe.h b/libs/tdlib/td/tddb/td/db/SqliteKeyValueSafe.h
new file mode 100644
index 0000000000..d63af3cfb2
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/SqliteKeyValueSafe.h
@@ -0,0 +1,36 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/db/SqliteConnectionSafe.h"
+#include "td/db/SqliteKeyValue.h"
+
+#include <memory>
+
+namespace td {
+
+class SqliteKeyValueSafe {
+ public:
+  SqliteKeyValueSafe(string name, std::shared_ptr<SqliteConnectionSafe> safe_connection)
+      : lsls_kv_([name = std::move(name), safe_connection = std::move(safe_connection)] {
+        SqliteKeyValue kv;
+        kv.init_with_connection(safe_connection->get().clone(), name).ensure();
+        return kv;
+      }) {
+  }
+  SqliteKeyValue &get() {
+    return lsls_kv_.get();
+  }
+  void close() {
+    lsls_kv_.clear_values();
+  }
+
+ private:
+  LazySchedulerLocalStorage<SqliteKeyValue> lsls_kv_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/SqliteStatement.cpp b/libs/tdlib/td/tddb/td/db/SqliteStatement.cpp
new file mode 100644
index 0000000000..c9ce8c3e8e
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/SqliteStatement.cpp
@@ -0,0 +1,203 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/db/SqliteStatement.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/StackAllocator.h"
+#include "td/utils/StringBuilder.h"
+
+#include "sqlite/sqlite3.h"
+
+namespace td {
+
+namespace {
+int printExplainQueryPlan(StringBuilder &sb, sqlite3_stmt *pStmt) {
+  const char *zSql = sqlite3_sql(pStmt);
+  if (zSql == nullptr) {
+    return SQLITE_ERROR;
+  }
+
+  sb << "Explain " << tag("cmd", zSql);
+  char *zExplain = sqlite3_mprintf("EXPLAIN QUERY PLAN %s", zSql);
+  if (zExplain == nullptr) {
+    return SQLITE_NOMEM;
+  }
+
+  sqlite3_stmt *pExplain; /* Compiled EXPLAIN QUERY PLAN command */
+  int rc = sqlite3_prepare_v2(sqlite3_db_handle(pStmt), zExplain, -1, &pExplain, nullptr);
+  sqlite3_free(zExplain);
+  if (rc != SQLITE_OK) {
+    return rc;
+  }
+
+  while (SQLITE_ROW == sqlite3_step(pExplain)) {
+    int iSelectid = sqlite3_column_int(pExplain, 0);
+    int iOrder = sqlite3_column_int(pExplain, 1);
+    int iFrom = sqlite3_column_int(pExplain, 2);
+    const char *zDetail = reinterpret_cast<const char *>(sqlite3_column_text(pExplain, 3));
+
+    sb << "\n" << iSelectid << " " << iOrder << " " << iFrom << " " << zDetail;
+  }
+
+  return sqlite3_finalize(pExplain);
+}
+}  // namespace
+
+SqliteStatement::SqliteStatement(sqlite3_stmt *stmt, std::shared_ptr<detail::RawSqliteDb> db)
+    : stmt_(stmt), db_(std::move(db)) {
+  CHECK(stmt != nullptr);
+}
+SqliteStatement::~SqliteStatement() = default;
+
+Result<string> SqliteStatement::explain() {
+  if (empty()) {
+    return Status::Error("No statement");
+  }
+  auto tmp = StackAllocator::alloc(10000);
+  StringBuilder sb(tmp.as_slice());
+  auto code = printExplainQueryPlan(sb, stmt_.get());
+  if (code != SQLITE_OK) {
+    return last_error();
+  }
+  if (sb.is_error()) {
+    return Status::Error("StringBuilder buffer overflow");
+  }
+  return sb.as_cslice().str();
+}
+Status SqliteStatement::bind_blob(int id, Slice blob) {
+  auto rc = sqlite3_bind_blob(stmt_.get(), id, blob.data(), static_cast<int>(blob.size()), nullptr);
+  if (rc != SQLITE_OK) {
+    return last_error();
+  }
+  return Status::OK();
+}
+Status SqliteStatement::bind_string(int id, Slice str) {
+  auto rc = sqlite3_bind_text(stmt_.get(), id, str.data(), static_cast<int>(str.size()), nullptr);
+  if (rc != SQLITE_OK) {
+    return last_error();
+  }
+  return Status::OK();
+}
+
+Status SqliteStatement::bind_int32(int id, int32 value) {
+  auto rc = sqlite3_bind_int(stmt_.get(), id, value);
+  if (rc != SQLITE_OK) {
+    return last_error();
+  }
+  return Status::OK();
+}
+Status SqliteStatement::bind_int64(int id, int64 value) {
+  auto rc = sqlite3_bind_int64(stmt_.get(), id, value);
+  if (rc != SQLITE_OK) {
+    return last_error();
+  }
+  return Status::OK();
+}
+Status SqliteStatement::bind_null(int id) {
+  auto rc = sqlite3_bind_null(stmt_.get(), id);
+  if (rc != SQLITE_OK) {
+    return last_error();
+  }
+  return Status::OK();
+}
+
+StringBuilder &operator<<(StringBuilder &sb, SqliteStatement::Datatype type) {
+  using Datatype = SqliteStatement::Datatype;
+  switch (type) {
+    case Datatype::Integer:
+      return sb << "Integer";
+    case Datatype::Float:
+      return sb << "Float";
+    case Datatype::Blob:
+      return sb << "Blob";
+    case Datatype::Null:
+      return sb << "Null";
+    case Datatype::Text:
+      return sb << "Text";
+  }
+  UNREACHABLE();
+  return sb;
+}
+Slice SqliteStatement::view_blob(int id) {
+  LOG_IF(ERROR, view_datatype(id) != Datatype::Blob) << view_datatype(id);
+  auto *data = sqlite3_column_blob(stmt_.get(), id);
+  auto size = sqlite3_column_bytes(stmt_.get(), id);
+  if (data == nullptr) {
+    return Slice();
+  }
+  return Slice(static_cast<const char *>(data), size);
+}
+Slice SqliteStatement::view_string(int id) {
+  LOG_IF(ERROR, view_datatype(id) != Datatype::Text) << view_datatype(id);
+  auto *data = sqlite3_column_text(stmt_.get(), id);
+  auto size = sqlite3_column_bytes(stmt_.get(), id);
+  if (data == nullptr) {
+    return Slice();
+  }
+  return Slice(data, size);
+}
+int32 SqliteStatement::view_int32(int id) {
+  LOG_IF(ERROR, view_datatype(id) != Datatype::Integer) << view_datatype(id);
+  return sqlite3_column_int(stmt_.get(), id);
+}
+int64 SqliteStatement::view_int64(int id) {
+  LOG_IF(ERROR, view_datatype(id) != Datatype::Integer) << view_datatype(id);
+  return sqlite3_column_int64(stmt_.get(), id);
+}
+SqliteStatement::Datatype SqliteStatement::view_datatype(int id) {
+  auto type = sqlite3_column_type(stmt_.get(), id);
+  switch (type) {
+    case SQLITE_INTEGER:
+      return Datatype::Integer;
+    case SQLITE_FLOAT:
+      return Datatype::Float;
+    case SQLITE_BLOB:
+      return Datatype::Blob;
+    case SQLITE_NULL:
+      return Datatype::Null;
+    case SQLITE3_TEXT:
+      return Datatype::Text;
+    default:
+      UNREACHABLE();
+  }
+}
+
+void SqliteStatement::reset() {
+  sqlite3_reset(stmt_.get());
+  state_ = Start;
+}
+
+Status SqliteStatement::step() {
+  if (state_ == Finish) {
+    return Status::Error("One has to reset statement");
+  }
+  VLOG(sqlite) << "Start step " << tag("cmd", sqlite3_sql(stmt_.get())) << tag("stmt", stmt_.get())
+               << tag("db", db_.get());
+  auto rc = sqlite3_step(stmt_.get());
+  VLOG(sqlite) << "Finish step " << tag("cmd", sqlite3_sql(stmt_.get())) << tag("stmt", stmt_.get())
+               << tag("db", db_.get());
+  if (rc == SQLITE_ROW) {
+    state_ = GotRow;
+    return Status::OK();
+  }
+  if (rc == SQLITE_DONE) {
+    state_ = Finish;
+    return Status::OK();
+  }
+  state_ = Finish;
+  return last_error();
+}
+
+void SqliteStatement::StmtDeleter::operator()(sqlite3_stmt *stmt) {
+  sqlite3_finalize(stmt);
+}
+
+Status SqliteStatement::last_error() {
+  return db_->last_error();
+}
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/SqliteStatement.h b/libs/tdlib/td/tddb/td/db/SqliteStatement.h
new file mode 100644
index 0000000000..2e2182ff7e
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/SqliteStatement.h
@@ -0,0 +1,80 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include "td/db/detail/RawSqliteDb.h"
+
+#include <memory>
+
+struct sqlite3;
+struct sqlite3_stmt;
+
+namespace td {
+
+class SqliteStatement {
+ public:
+  SqliteStatement() = default;
+  SqliteStatement(const SqliteStatement &other) = delete;
+  SqliteStatement &operator=(const SqliteStatement &other) = delete;
+  SqliteStatement(SqliteStatement &&other) = default;
+  SqliteStatement &operator=(SqliteStatement &&other) = default;
+  ~SqliteStatement();
+
+  Status bind_blob(int id, Slice blob) TD_WARN_UNUSED_RESULT;
+  Status bind_string(int id, Slice str) TD_WARN_UNUSED_RESULT;
+  Status bind_int32(int id, int32 value) TD_WARN_UNUSED_RESULT;
+  Status bind_int64(int id, int64 value) TD_WARN_UNUSED_RESULT;
+  Status bind_null(int id) TD_WARN_UNUSED_RESULT;
+  Status step() TD_WARN_UNUSED_RESULT;
+  Slice view_string(int id) TD_WARN_UNUSED_RESULT;
+  Slice view_blob(int id) TD_WARN_UNUSED_RESULT;
+  int32 view_int32(int id) TD_WARN_UNUSED_RESULT;
+  int64 view_int64(int id) TD_WARN_UNUSED_RESULT;
+  enum class Datatype { Integer, Float, Blob, Null, Text };
+  Datatype view_datatype(int id);
+
+  Result<string> explain();
+
+  bool can_step() const {
+    return state_ != Finish;
+  }
+  bool has_row() const {
+    return state_ == GotRow;
+  }
+  bool empty() const {
+    return !stmt_;
+  }
+
+  void reset();
+
+  auto guard() {
+    return ScopeExit{} + [this] { this->reset(); };
+  }
+
+  // TODO get row
+
+ private:
+  friend class SqliteDb;
+  SqliteStatement(sqlite3_stmt *stmt, std::shared_ptr<detail::RawSqliteDb> db);
+
+  class StmtDeleter {
+   public:
+    void operator()(sqlite3_stmt *stmt);
+  };
+
+  enum { Start, GotRow, Finish } state_ = Start;
+
+  std::unique_ptr<sqlite3_stmt, StmtDeleter> stmt_;
+  std::shared_ptr<detail::RawSqliteDb> db_;
+
+  Status last_error();
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/TsSeqKeyValue.h b/libs/tdlib/td/tddb/td/db/TsSeqKeyValue.h
new file mode 100644
index 0000000000..8d94d79673
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/TsSeqKeyValue.h
@@ -0,0 +1,71 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/db/SeqKeyValue.h"
+
+#include "td/utils/port/RwMutex.h"
+#include "td/utils/Slice.h"
+
+#include <unordered_map>
+#include <utility>
+
+namespace td {
+class TsSeqKeyValue {
+ public:
+  using SeqNo = SeqKeyValue::SeqNo;
+  TsSeqKeyValue() = default;
+  explicit TsSeqKeyValue(SeqKeyValue kv) : kv_(std::move(kv)) {
+  }
+
+  TsSeqKeyValue(TsSeqKeyValue &&) = default;
+  TsSeqKeyValue &operator=(TsSeqKeyValue &&) = default;
+  TsSeqKeyValue(const TsSeqKeyValue &) = delete;
+  TsSeqKeyValue &operator=(const TsSeqKeyValue &) = delete;
+  ~TsSeqKeyValue() = default;
+
+  SeqNo set(Slice key, Slice value) {
+    auto lock = rw_mutex_.lock_write().move_as_ok();
+    return kv_.set(key, value);
+  }
+  std::pair<SeqNo, RwMutex::WriteLock> set_and_lock(Slice key, Slice value) {
+    auto lock = rw_mutex_.lock_write().move_as_ok();
+    return std::make_pair(kv_.set(key, value), std::move(lock));
+  }
+  SeqNo erase(const string &key) {
+    auto lock = rw_mutex_.lock_write().move_as_ok();
+    return kv_.erase(key);
+  }
+  std::pair<SeqNo, RwMutex::WriteLock> erase_and_lock(const string &key) {
+    auto lock = rw_mutex_.lock_write().move_as_ok();
+    return std::make_pair(kv_.erase(key), std::move(lock));
+  }
+  string get(const string &key) {
+    auto lock = rw_mutex_.lock_read().move_as_ok();
+    return kv_.get(key);
+  }
+  size_t size() const {
+    return kv_.size();
+  }
+  std::unordered_map<string, string> get_all() {
+    auto lock = rw_mutex_.lock_write().move_as_ok();
+    return kv_.get_all();
+  }
+  // not thread safe method
+  SeqKeyValue &inner() {
+    return kv_;
+  }
+
+  auto lock() {
+    return rw_mutex_.lock_write().move_as_ok();
+  }
+
+ private:
+  RwMutex rw_mutex_;
+  SeqKeyValue kv_;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/binlog/Binlog.cpp b/libs/tdlib/td/tddb/td/db/binlog/Binlog.cpp
new file mode 100644
index 0000000000..5d76028dba
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/binlog/Binlog.cpp
@@ -0,0 +1,629 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/db/binlog/Binlog.h"
+
+#include "td/db/binlog/detail/BinlogEventsBuffer.h"
+#include "td/db/binlog/detail/BinlogEventsProcessor.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/Clocks.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/path.h"
+#include "td/utils/port/Stat.h"
+#include "td/utils/Random.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Status.h"
+#include "td/utils/Time.h"
+#include "td/utils/tl_helpers.h"
+#include "td/utils/tl_parsers.h"
+
+namespace td {
+namespace detail {
+struct AesCtrEncryptionEvent {
+  static constexpr size_t min_salt_size() {
+    return 16;  // 256 bits
+  }
+  static constexpr size_t default_salt_size() {
+    return 32;  // 256 bits
+  }
+  static constexpr size_t key_size() {
+    return 32;  // 256 bits
+  }
+  static constexpr size_t iv_size() {
+    return 16;  // 128 bits
+  }
+  static constexpr size_t hash_size() {
+    return 32;  // 256 bits
+  }
+  static constexpr size_t kdf_iteration_count() {
+    return 60002;
+  }
+  static constexpr size_t kdf_fast_iteration_count() {
+    return 2;
+  }
+
+  BufferSlice key_salt_;
+  BufferSlice iv_;
+  BufferSlice key_hash_;
+
+  BufferSlice generate_key(const DbKey &db_key) {
+    CHECK(!db_key.is_empty());
+    BufferSlice key(key_size());
+    size_t iteration_count = kdf_iteration_count();
+    if (db_key.is_raw_key()) {
+      iteration_count = kdf_fast_iteration_count();
+    }
+    pbkdf2_sha256(db_key.data(), key_salt_.as_slice(), narrow_cast<int>(iteration_count), key.as_slice());
+    return key;
+  }
+  BufferSlice generate_hash(Slice key) {
+    BufferSlice hash(hash_size());
+    hmac_sha256(key, "cucumbers everywhere", hash.as_slice());
+    return hash;
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+    using td::store;
+    BEGIN_STORE_FLAGS();
+    END_STORE_FLAGS();
+    store(key_salt_, storer);
+    store(iv_, storer);
+    store(key_hash_, storer);
+  }
+  template <class ParserT>
+  void parse(ParserT &&parser) {
+    using td::parse;
+    BEGIN_PARSE_FLAGS();
+    END_PARSE_FLAGS();
+    parse(key_salt_, parser);
+    parse(iv_, parser);
+    parse(key_hash_, parser);
+  }
+};
+
+class BinlogReader {
+ public:
+  BinlogReader() = default;
+  explicit BinlogReader(ChainBufferReader *input) : input_(input) {
+  }
+  void set_input(ChainBufferReader *input) {
+    input_ = input;
+  }
+
+  int64 offset() {
+    return offset_;
+  }
+  Result<size_t> read_next(BinlogEvent *event) {
+    if (state_ == ReadLength) {
+      if (input_->size() < 4) {
+        return 4;
+      }
+      auto it = input_->clone();
+
+      char buf[4];
+      it.advance(4, MutableSlice(buf, 4));
+      size_ = static_cast<size_t>(TlParser(Slice(buf, 4)).fetch_int());
+
+      if (size_ > MAX_EVENT_SIZE) {
+        return Status::Error(PSLICE() << "Too big event " << tag("size", size_));
+      }
+      if (size_ < MIN_EVENT_SIZE) {
+        return Status::Error(PSLICE() << "Too small event " << tag("size", size_));
+      }
+      state_ = ReadEvent;
+    }
+
+    if (input_->size() < size_) {
+      return size_;
+    }
+
+    TRY_STATUS(event->init(input_->cut_head(size_).move_as_buffer_slice()));
+    offset_ += size_;
+    event->offset_ = offset_;
+    state_ = ReadLength;
+    return 0;
+  }
+
+ private:
+  ChainBufferReader *input_;
+  enum { ReadLength, ReadEvent } state_ = ReadLength;
+  size_t size_{0};
+  int64 offset_{0};
+};
+}  // namespace detail
+
+bool Binlog::IGNORE_ERASE_HACK = false;
+
+Binlog::Binlog() = default;
+
+Binlog::~Binlog() {
+  close().ignore();
+}
+
+Result<FileFd> Binlog::open_binlog(CSlice path, int32 flags) {
+  TRY_RESULT(fd, FileFd::open(path, flags));
+  TRY_STATUS(fd.lock(FileFd::LockFlags::Write, 100));
+  return std::move(fd);
+}
+
+Status Binlog::init(string path, const Callback &callback, DbKey db_key, DbKey old_db_key, int32 dummy,
+                    const Callback &debug_callback) {
+  close().ignore();
+
+  db_key_ = std::move(db_key);
+  old_db_key_ = std::move(old_db_key);
+
+  processor_ = std::make_unique<detail::BinlogEventsProcessor>();
+  // Turn off BinlogEventsBuffer
+  // events_buffer_ = std::make_unique<detail::BinlogEventsBuffer>();
+
+  // try to restore binlog from regenerated version
+  if (stat(path).is_error()) {
+    rename(PSLICE() << path << ".new", path).ignore();
+  }
+
+  info_ = BinlogInfo();
+  info_.was_created = stat(path).is_error();
+
+  TRY_RESULT(fd, open_binlog(path, FileFd::Flags::Read | FileFd::Flags::Write | FileFd::Flags::Create));
+  fd_ = BufferedFdBase<FileFd>(std::move(fd));
+  fd_size_ = 0;
+  path_ = std::move(path);
+
+  auto status = load_binlog(callback, debug_callback);
+  if (status.is_error()) {
+    close().ignore();
+    return status;
+  }
+  info_.last_id = processor_->last_id();
+  last_id_ = processor_->last_id();
+  if (info_.wrong_password) {
+    close().ignore();
+    return Status::Error(Error::WrongPassword, "Wrong password");
+  }
+
+  if ((!db_key_.is_empty() && !db_key_used_) || (db_key_.is_empty() && encryption_type_ != EncryptionType::None)) {
+    aes_ctr_key_salt_ = BufferSlice();
+    do_reindex();
+  }
+
+  info_.is_opened = true;
+  return Status::OK();
+}
+
+void Binlog::add_event(BinlogEvent &&event) {
+  if (!events_buffer_) {
+    do_add_event(std::move(event));
+  } else {
+    events_buffer_->add_event(std::move(event));
+  }
+  lazy_flush();
+
+  if (state_ == State::Run) {
+    auto fd_size = fd_size_;
+    if (events_buffer_) {
+      fd_size += events_buffer_->size();
+    }
+    auto need_reindex = [&](int64 min_size, int rate) {
+      return fd_size > min_size && fd_size / rate > processor_->total_raw_events_size();
+    };
+    if (need_reindex(100000, 5) || need_reindex(500000, 2)) {
+      LOG(INFO) << tag("fd_size", format::as_size(fd_size))
+                << tag("total events size", format::as_size(processor_->total_raw_events_size()));
+      do_reindex();
+    }
+  }
+}
+
+size_t Binlog::flush_events_buffer(bool force) {
+  if (!events_buffer_) {
+    return 0;
+  }
+  if (!force && !events_buffer_->need_flush()) {
+    return events_buffer_->size();
+  }
+  CHECK(!in_flush_events_buffer_);
+  in_flush_events_buffer_ = true;
+  events_buffer_->flush([&](BinlogEvent &&event) { this->do_add_event(std::move(event)); });
+  in_flush_events_buffer_ = false;
+  return 0;
+}
+
+void Binlog::do_add_event(BinlogEvent &&event) {
+  if (event.flags_ & BinlogEvent::Flags::Partial) {
+    event.flags_ &= ~BinlogEvent::Flags::Partial;
+    pending_events_.emplace_back(std::move(event));
+  } else {
+    for (auto &pending_event : pending_events_) {
+      do_event(std::move(pending_event));
+    }
+    pending_events_.clear();
+    do_event(std::move(event));
+  }
+}
+
+Status Binlog::close(bool need_sync) {
+  if (fd_.empty()) {
+    return Status::OK();
+  }
+  SCOPE_EXIT {
+    path_ = "";
+    info_.is_opened = false;
+    fd_.close();
+    need_sync_ = false;
+  };
+  if (need_sync) {
+    sync();
+  } else {
+    flush();
+  }
+  return Status::OK();
+}
+
+void Binlog::change_key(DbKey new_db_key) {
+  db_key_ = std::move(new_db_key);
+  aes_ctr_key_salt_ = BufferSlice();
+  do_reindex();
+}
+
+Status Binlog::close_and_destroy() {
+  auto path = path_;
+  auto close_status = close(false);
+  destroy(path).ignore();
+  return close_status;
+}
+Status Binlog::destroy(Slice path) {
+  unlink(PSLICE() << path).ignore();
+  unlink(PSLICE() << path << ".new").ignore();
+  return Status::OK();
+}
+
+void Binlog::do_event(BinlogEvent &&event) {
+  fd_events_++;
+  fd_size_ += event.raw_event_.size();
+
+  if (state_ == State::Run || state_ == State::Reindex) {
+    VLOG(binlog) << "Write binlog event: " << format::cond(state_ == State::Reindex, "[reindex] ") << event;
+    switch (encryption_type_) {
+      case EncryptionType::None: {
+        buffer_writer_.append(event.raw_event_.clone());
+        break;
+      }
+      case EncryptionType::AesCtr: {
+        buffer_writer_.append(event.raw_event_.as_slice());
+        break;
+      }
+    }
+  }
+
+  if (event.type_ < 0) {
+    if (event.type_ == BinlogEvent::ServiceTypes::AesCtrEncryption) {
+      detail::AesCtrEncryptionEvent encryption_event;
+      encryption_event.parse(TlParser(event.data_));
+
+      BufferSlice key;
+      if (aes_ctr_key_salt_.as_slice() == encryption_event.key_salt_.as_slice()) {
+        key = BufferSlice(Slice(aes_ctr_key_.raw, sizeof(aes_ctr_key_.raw)));
+      } else if (!db_key_.is_empty()) {
+        key = encryption_event.generate_key(db_key_);
+      }
+
+      if (encryption_event.generate_hash(key.as_slice()).as_slice() != encryption_event.key_hash_.as_slice()) {
+        CHECK(state_ == State::Load);
+        if (!old_db_key_.is_empty()) {
+          key = encryption_event.generate_key(old_db_key_);
+          if (encryption_event.generate_hash(key.as_slice()).as_slice() != encryption_event.key_hash_.as_slice()) {
+            info_.wrong_password = true;
+          }
+        } else {
+          info_.wrong_password = true;
+        }
+      } else {
+        db_key_used_ = true;
+      }
+
+      encryption_type_ = EncryptionType::AesCtr;
+
+      aes_ctr_key_salt_ = encryption_event.key_salt_.copy();
+      update_encryption(key.as_slice(), encryption_event.iv_.as_slice());
+
+      if (state_ == State::Load) {
+        update_read_encryption();
+        LOG(INFO) << "Load: init encryption";
+      } else {
+        CHECK(state_ == State::Reindex);
+        flush();
+        update_write_encryption();
+        //LOG(INFO) << format::cond(state_ == State::Run, "Run", "Reindex") << ": init encryption";
+      }
+      return;
+    }
+  }
+
+  if (state_ != State::Reindex) {
+    processor_->add_event(std::move(event));
+  }
+}
+
+void Binlog::sync() {
+  flush();
+  if (need_sync_) {
+    auto status = fd_.sync();
+    LOG_IF(FATAL, status.is_error()) << "Failed to sync binlog: " << status;
+    need_sync_ = false;
+  }
+}
+
+void Binlog::flush() {
+  if (state_ == State::Load) {
+    return;
+  }
+  flush_events_buffer(true);
+  // NB: encryption happens during flush
+  if (byte_flow_flag_) {
+    byte_flow_source_.wakeup();
+  }
+  auto r_written = fd_.flush_write();
+  r_written.ensure();
+  auto written = r_written.ok();
+  if (written > 0) {
+    need_sync_ = true;
+  }
+  need_flush_since_ = 0;
+  LOG_IF(FATAL, fd_.need_flush_write()) << "Failed to flush binlog";
+}
+
+void Binlog::lazy_flush() {
+  size_t events_buffer_size = flush_events_buffer(false /*force*/);
+  buffer_reader_.sync_with_writer();
+  auto size = buffer_reader_.size() + events_buffer_size;
+  if (size > (1 << 14)) {
+    flush();
+  } else if (size > 0 && need_flush_since_ == 0) {
+    need_flush_since_ = Time::now_cached();
+  }
+}
+
+void Binlog::update_read_encryption() {
+  CHECK(binlog_reader_ptr_);
+  switch (encryption_type_) {
+    case EncryptionType::None: {
+      binlog_reader_ptr_->set_input(&buffer_reader_);
+      byte_flow_flag_ = false;
+      break;
+    }
+    case EncryptionType::AesCtr: {
+      byte_flow_source_ = ByteFlowSource(&buffer_reader_);
+      aes_xcode_byte_flow_ = AesCtrByteFlow();
+      aes_xcode_byte_flow_.init(std::move(aes_ctr_state_));
+      byte_flow_sink_ = ByteFlowSink();
+      byte_flow_source_ >> aes_xcode_byte_flow_ >> byte_flow_sink_;
+      byte_flow_flag_ = true;
+      binlog_reader_ptr_->set_input(byte_flow_sink_.get_output());
+      break;
+    }
+  }
+}
+
+void Binlog::update_write_encryption() {
+  switch (encryption_type_) {
+    case EncryptionType::None: {
+      fd_.set_output_reader(&buffer_reader_);
+      byte_flow_flag_ = false;
+      break;
+    }
+    case EncryptionType::AesCtr: {
+      byte_flow_source_ = ByteFlowSource(&buffer_reader_);
+      aes_xcode_byte_flow_ = AesCtrByteFlow();
+      aes_xcode_byte_flow_.init(std::move(aes_ctr_state_));
+      byte_flow_sink_ = ByteFlowSink();
+      byte_flow_source_ >> aes_xcode_byte_flow_ >> byte_flow_sink_;
+      byte_flow_flag_ = true;
+      fd_.set_output_reader(byte_flow_sink_.get_output());
+      break;
+    }
+  }
+}
+
+Status Binlog::load_binlog(const Callback &callback, const Callback &debug_callback) {
+  state_ = State::Load;
+
+  buffer_writer_ = ChainBufferWriter();
+  buffer_reader_ = buffer_writer_.extract_reader();
+  fd_.set_input_writer(&buffer_writer_);
+  detail::BinlogReader reader;
+  binlog_reader_ptr_ = &reader;
+
+  update_read_encryption();
+
+  bool ready_flag = false;
+  fd_.update_flags(Fd::Flag::Read);
+  info_.wrong_password = false;
+  while (true) {
+    BinlogEvent event;
+    auto r_need_size = reader.read_next(&event);
+    if (r_need_size.is_error()) {
+      LOG(ERROR) << r_need_size.error();
+      break;
+    }
+    auto need_size = r_need_size.move_as_ok();
+    // LOG(ERROR) << "need size = " << need_size;
+    if (need_size == 0) {
+      if (IGNORE_ERASE_HACK && event.type_ == BinlogEvent::ServiceTypes::Empty &&
+          (event.flags_ & BinlogEvent::Flags::Rewrite) != 0) {
+        // skip erase
+      } else {
+        if (debug_callback) {
+          debug_callback(event);
+        }
+        do_add_event(std::move(event));
+        if (info_.wrong_password) {
+          return Status::OK();
+        }
+      }
+      ready_flag = false;
+    } else {
+      // TODO(now): fix bug
+      if (ready_flag) {
+        break;
+      }
+      TRY_STATUS(fd_.flush_read(max(need_size, static_cast<size_t>(4096))));
+      buffer_reader_.sync_with_writer();
+      if (byte_flow_flag_) {
+        byte_flow_source_.wakeup();
+      }
+      ready_flag = true;
+    }
+  }
+
+  auto offset = processor_->offset();
+  processor_->for_each([&](BinlogEvent &event) {
+    VLOG(binlog) << "Replay binlog event: " << event;
+    if (callback) {
+      callback(event);
+    }
+  });
+
+  auto fd_size = fd_.get_size();
+  if (offset != fd_size) {
+    LOG(ERROR) << "Truncate " << tag("path", path_) << tag("old_size", fd_size) << tag("new_size", offset);
+    fd_.seek(offset).ensure();
+    fd_.truncate_to_current_position(offset).ensure();
+    db_key_used_ = false;  // force reindex
+  }
+  CHECK(IGNORE_ERASE_HACK || fd_size_ == offset) << fd_size << " " << fd_size_ << " " << offset;
+  binlog_reader_ptr_ = nullptr;
+  state_ = State::Run;
+
+  buffer_writer_ = ChainBufferWriter();
+  buffer_reader_ = buffer_writer_.extract_reader();
+
+  // reuse aes_ctr_state_
+  if (encryption_type_ == EncryptionType::AesCtr) {
+    aes_ctr_state_ = aes_xcode_byte_flow_.move_aes_ctr_state();
+  }
+  update_write_encryption();
+
+  return Status::OK();
+}
+
+static int64 file_size(CSlice path) {
+  auto r_stat = stat(path);
+  if (r_stat.is_error()) {
+    return 0;
+  }
+  return r_stat.ok().size_;
+}
+
+void Binlog::update_encryption(Slice key, Slice iv) {
+  MutableSlice(aes_ctr_key_.raw, sizeof(aes_ctr_key_.raw)).copy_from(key);
+  UInt128 aes_ctr_iv;
+  MutableSlice(aes_ctr_iv.raw, sizeof(aes_ctr_iv.raw)).copy_from(iv);
+  aes_ctr_state_.init(aes_ctr_key_, aes_ctr_iv);
+}
+
+void Binlog::reset_encryption() {
+  if (db_key_.is_empty()) {
+    encryption_type_ = EncryptionType::None;
+    return;
+  }
+
+  using EncryptionEvent = detail::AesCtrEncryptionEvent;
+  EncryptionEvent event;
+
+  if (aes_ctr_key_salt_.empty()) {
+    event.key_salt_ = BufferSlice(EncryptionEvent::default_salt_size());
+    Random::secure_bytes(event.key_salt_.as_slice());
+  } else {
+    event.key_salt_ = aes_ctr_key_salt_.clone();
+  }
+  event.iv_ = BufferSlice(EncryptionEvent::iv_size());
+  Random::secure_bytes(event.iv_.as_slice());
+
+  BufferSlice key;
+  if (aes_ctr_key_salt_.as_slice() == event.key_salt_.as_slice()) {
+    key = BufferSlice(Slice(aes_ctr_key_.raw, sizeof(aes_ctr_key_.raw)));
+  } else {
+    key = event.generate_key(db_key_);
+  }
+
+  event.key_hash_ = event.generate_hash(key.as_slice());
+
+  do_event(BinlogEvent(
+      BinlogEvent::create_raw(0, BinlogEvent::ServiceTypes::AesCtrEncryption, 0, create_default_storer(event))));
+}
+
+void Binlog::do_reindex() {
+  flush_events_buffer(true);
+  // start reindex
+  CHECK(state_ == State::Run);
+  state_ = State::Reindex;
+  SCOPE_EXIT {
+    state_ = State::Run;
+  };
+
+  auto start_time = Clocks::monotonic();
+  auto start_size = file_size(path_);
+  auto start_events = fd_events_;
+
+  string new_path = path_ + ".new";
+
+  auto r_opened_file = open_binlog(new_path, FileFd::Flags::Write | FileFd::Flags::Create | FileFd::Truncate);
+  if (r_opened_file.is_error()) {
+    LOG(ERROR) << "Can't open new binlog for regenerate: " << r_opened_file.error();
+    return;
+  }
+  fd_.close();
+  fd_ = BufferedFdBase<FileFd>(r_opened_file.move_as_ok());
+
+  buffer_writer_ = ChainBufferWriter();
+  buffer_reader_ = buffer_writer_.extract_reader();
+  encryption_type_ = EncryptionType::None;
+  update_write_encryption();
+
+  // reindex
+  fd_size_ = 0;
+  fd_events_ = 0;
+  reset_encryption();
+  processor_->for_each([&](BinlogEvent &event) {
+    do_event(std::move(event));  // NB: no move is actually happens
+  });
+  need_sync_ = true;  // must sync creation of the file
+  sync();
+
+  // finish_reindex
+  auto status = unlink(path_);
+  LOG_IF(FATAL, status.is_error()) << "Failed to unlink old binlog: " << status;
+  status = rename(new_path, path_);
+  LOG_IF(FATAL, status.is_error()) << "Failed to rename binlog: " << status;
+
+  auto finish_time = Clocks::monotonic();
+  auto finish_size = fd_size_;
+  auto finish_events = fd_events_;
+  CHECK(fd_size_ == file_size(path_));
+
+  // TODO: print warning only if time or ratio is suspicious
+  double ratio = static_cast<double>(start_size) / static_cast<double>(finish_size + 1);
+  LOG(INFO) << "regenerate index " << tag("name", path_) << tag("time", format::as_time(finish_time - start_time))
+            << tag("before_size", format::as_size(start_size)) << tag("after_size", format::as_size(finish_size))
+            << tag("ratio", ratio) << tag("before_events", start_events) << tag("after_events", finish_events);
+
+  buffer_writer_ = ChainBufferWriter();
+  buffer_reader_ = buffer_writer_.extract_reader();
+
+  // reuse aes_ctr_state_
+  if (encryption_type_ == EncryptionType::AesCtr) {
+    aes_ctr_state_ = aes_xcode_byte_flow_.move_aes_ctr_state();
+  }
+  update_write_encryption();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/binlog/Binlog.h b/libs/tdlib/td/tddb/td/db/binlog/Binlog.h
new file mode 100644
index 0000000000..cdda868b4e
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/binlog/Binlog.h
@@ -0,0 +1,143 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/db/binlog/BinlogEvent.h"
+#include "td/db/DbKey.h"
+
+#include "td/utils/AesCtrByteFlow.h"
+#include "td/utils/buffer.h"
+#include "td/utils/BufferedFd.h"
+#include "td/utils/ByteFlow.h"
+#include "td/utils/common.h"
+#include "td/utils/crypto.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <functional>
+
+namespace td {
+struct BinlogInfo {
+  bool was_created;
+  uint64 last_id;
+  bool is_encrypted{false};
+  bool wrong_password{false};
+  bool is_opened{false};
+};
+
+namespace detail {
+class BinlogReader;
+class BinlogEventsProcessor;
+class BinlogEventsBuffer;
+};  // namespace detail
+
+class Binlog {
+ public:
+  enum Error : int { WrongPassword = -1 };
+  static bool IGNORE_ERASE_HACK;
+  Binlog();
+  Binlog(const Binlog &other) = delete;
+  Binlog &operator=(const Binlog &other) = delete;
+  Binlog(Binlog &&other) = delete;
+  Binlog &operator=(Binlog &&other) = delete;
+  ~Binlog();
+
+  using Callback = std::function<void(const BinlogEvent &)>;
+  Status init(string path, const Callback &callback, DbKey db_key = DbKey::empty(), DbKey old_db_key = DbKey::empty(),
+              int32 dummy = -1, const Callback &debug_callback = Callback()) TD_WARN_UNUSED_RESULT;
+
+  uint64 next_id() {
+    return ++last_id_;
+  }
+  uint64 next_id(int32 shift) {
+    auto res = last_id_ + 1;
+    last_id_ += shift;
+    return res;
+  }
+  uint64 peek_next_id() const {
+    return last_id_ + 1;
+  }
+
+  bool empty() const {
+    return fd_.empty();
+  }
+
+  void add_raw_event(BufferSlice &&raw_event) {
+    add_event(BinlogEvent(std::move(raw_event)));
+  }
+
+  void add_event(BinlogEvent &&event);
+  void sync();
+  void flush();
+  void lazy_flush();
+  double need_flush_since() const {
+    return need_flush_since_;
+  }
+  void change_key(DbKey new_db_key);
+
+  Status close(bool need_sync = true) TD_WARN_UNUSED_RESULT;
+  Status close_and_destroy() TD_WARN_UNUSED_RESULT;
+  static Status destroy(Slice path) TD_WARN_UNUSED_RESULT;
+
+  CSlice get_path() const {
+    return path_;
+  }
+
+  BinlogInfo get_info() const {  // works even after binlog was closed
+    return info_;
+  }
+
+ private:
+  BufferedFdBase<FileFd> fd_;
+  ChainBufferWriter buffer_writer_;
+  ChainBufferReader buffer_reader_;
+  detail::BinlogReader *binlog_reader_ptr_;
+
+  BinlogInfo info_;
+  DbKey db_key_;
+  bool db_key_used_ = false;
+  DbKey old_db_key_;
+  enum class EncryptionType { None, AesCtr } encryption_type_ = EncryptionType::None;
+
+  // AesCtrEncryption
+  BufferSlice aes_ctr_key_salt_;
+  UInt256 aes_ctr_key_;
+  AesCtrState aes_ctr_state_;
+
+  bool byte_flow_flag_ = false;
+  ByteFlowSource byte_flow_source_;
+  ByteFlowSink byte_flow_sink_;
+  AesCtrByteFlow aes_xcode_byte_flow_;
+
+  int64 fd_size_{0};
+  uint64 fd_events_{0};
+  string path_;
+  std::vector<BinlogEvent> pending_events_;
+  std::unique_ptr<detail::BinlogEventsProcessor> processor_;
+  std::unique_ptr<detail::BinlogEventsBuffer> events_buffer_;
+  bool in_flush_events_buffer_{false};
+  uint64 last_id_{0};
+  double need_flush_since_ = 0;
+  bool need_sync_{false};
+  enum class State { Empty, Load, Reindex, Run } state_{State::Empty};
+
+  static constexpr uint32 MAX_EVENT_SIZE = 65536;
+
+  Result<FileFd> open_binlog(CSlice path, int32 flags);
+  size_t flush_events_buffer(bool force);
+  void do_add_event(BinlogEvent &&event);
+  void do_event(BinlogEvent &&event);
+  Status load_binlog(const Callback &callback, const Callback &debug_callback = Callback()) TD_WARN_UNUSED_RESULT;
+  void do_reindex();
+
+  void update_encryption(Slice key, Slice iv);
+  void reset_encryption();
+  void update_read_encryption();
+  void update_write_encryption();
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/binlog/BinlogEvent.cpp b/libs/tdlib/td/tddb/td/db/binlog/BinlogEvent.cpp
new file mode 100644
index 0000000000..e4584e920e
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/binlog/BinlogEvent.cpp
@@ -0,0 +1,38 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/db/binlog/BinlogEvent.h"
+
+#include "td/utils/tl_parsers.h"
+
+namespace td {
+int32 VERBOSITY_NAME(binlog) = VERBOSITY_NAME(DEBUG) + 8;
+
+Status BinlogEvent::init(BufferSlice &&raw_event, bool check_crc) {
+  TlParser parser(raw_event.as_slice());
+  size_ = parser.fetch_int();
+  CHECK(size_ == raw_event.size());
+  id_ = parser.fetch_long();
+  type_ = parser.fetch_int();
+  flags_ = parser.fetch_int();
+  extra_ = parser.fetch_long();
+  CHECK(size_ >= MIN_EVENT_SIZE);
+  auto slice_data = parser.fetch_string_raw<Slice>(size_ - MIN_EVENT_SIZE);
+  data_ = MutableSlice(const_cast<char *>(slice_data.begin()), slice_data.size());
+  crc32_ = static_cast<uint32>(parser.fetch_int());
+  if (check_crc) {
+    CHECK(size_ >= EVENT_TAIL_SIZE);
+    auto calculated_crc = crc32(raw_event.as_slice().truncate(size_ - EVENT_TAIL_SIZE));
+    if (calculated_crc != crc32_) {
+      return Status::Error(PSLICE() << "crc mismatch " << tag("actual", format::as_hex(calculated_crc))
+                                    << tag("expected", format::as_hex(crc32_)));
+    }
+  }
+  raw_event_ = std::move(raw_event);
+  return Status::OK();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/binlog/BinlogEvent.h b/libs/tdlib/td/tddb/td/db/binlog/BinlogEvent.h
new file mode 100644
index 0000000000..1874543dff
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/binlog/BinlogEvent.h
@@ -0,0 +1,109 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/crypto.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/Storer.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tl_storers.h"
+
+namespace td {
+struct EmptyStorerImpl {
+  EmptyStorerImpl() {
+  }
+
+  template <class StorerT>
+  void store(StorerT &storer) const {
+  }
+};
+
+inline auto EmptyStorer() {
+  static const EmptyStorerImpl impl;
+  return create_default_storer(impl);
+}
+
+static constexpr size_t MAX_EVENT_SIZE = 1 << 24;
+static constexpr size_t EVENT_HEADER_SIZE = 4 + 8 + 4 + 4 + 8;
+static constexpr size_t EVENT_TAIL_SIZE = 4;
+static constexpr size_t MIN_EVENT_SIZE = EVENT_HEADER_SIZE + EVENT_TAIL_SIZE;
+
+extern int32 VERBOSITY_NAME(binlog);
+
+// TODO: smaller BinlogEvent
+struct BinlogEvent {
+  int64 offset_;
+
+  uint32 size_;
+  uint64 id_;
+  int32 type_;  // type can be merged with flags
+  int32 flags_;
+  uint64 extra_;
+  MutableSlice data_;
+  uint32 crc32_;
+
+  BufferSlice raw_event_;
+
+  enum ServiceTypes { Header = -1, Empty = -2, AesCtrEncryption = -3, NoEncryption = -4 };
+  enum Flags { Rewrite = 1, Partial = 2 };
+
+  void clear() {
+    raw_event_ = BufferSlice();
+  }
+  bool empty() const {
+    return raw_event_.empty();
+  }
+  BinlogEvent clone() const {
+    BinlogEvent result;
+    result.init(raw_event_.clone()).ensure();
+    return result;
+  }
+
+  BufferSlice data_as_buffer_slice() const {
+    return raw_event_.from_slice(data_);
+  }
+
+  BinlogEvent() = default;
+  explicit BinlogEvent(BufferSlice &&raw_event) {
+    init(std::move(raw_event), false).ensure();
+  }
+  Status init(BufferSlice &&raw_event, bool check_crc = true) TD_WARN_UNUSED_RESULT;
+
+  static BufferSlice create_raw(uint64 id, int32 type, int32 flags, const Storer &storer);
+};
+
+inline StringBuilder &operator<<(StringBuilder &sb, const BinlogEvent &event) {
+  return sb << "LogEvent[" << tag("id", format::as_hex(event.id_)) << tag("type", event.type_)
+            << tag("flags", event.flags_) << tag("data", format::as_hex_dump<4>(event.data_)) << "]";
+}
+
+// Implementation
+inline BufferSlice BinlogEvent::create_raw(uint64 id, int32 type, int32 flags, const Storer &storer) {
+  auto raw_event = BufferSlice{storer.size() + MIN_EVENT_SIZE};
+
+  TlStorerUnsafe tl_storer(raw_event.as_slice().begin());
+  tl_storer.store_int(narrow_cast<int32>(raw_event.size()));
+  tl_storer.store_long(id);
+  tl_storer.store_int(type);
+  tl_storer.store_int(flags);
+  tl_storer.store_long(0);
+
+  CHECK(tl_storer.get_buf() == raw_event.as_slice().begin() + EVENT_HEADER_SIZE);
+  tl_storer.store_storer(storer);
+
+  CHECK(tl_storer.get_buf() == raw_event.as_slice().end() - EVENT_TAIL_SIZE);
+  tl_storer.store_int(::td::crc32(raw_event.as_slice().truncate(raw_event.size() - EVENT_TAIL_SIZE)));
+
+  return raw_event;
+}
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/binlog/BinlogHelper.h b/libs/tdlib/td/tddb/td/db/binlog/BinlogHelper.h
new file mode 100644
index 0000000000..1224ac4ac2
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/binlog/BinlogHelper.h
@@ -0,0 +1,45 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/db/binlog/BinlogEvent.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Storer.h"
+
+namespace td {
+class BinlogHelper {
+ public:
+  template <class BinlogT, class StorerT>
+  static uint64 add(const BinlogT &binlog_ptr, int32 type, const StorerT &storer, Promise<> promise = Promise<>()) {
+    auto logevent_id = binlog_ptr->next_id();
+    binlog_ptr->add_raw_event(logevent_id, BinlogEvent::create_raw(logevent_id, type, 0, storer), std::move(promise));
+    return logevent_id;
+  }
+
+  template <class BinlogT, class StorerT>
+  static uint64 rewrite(const BinlogT &binlog_ptr, uint64 logevent_id, int32 type, const StorerT &storer,
+                        Promise<> promise = Promise<>()) {
+    auto seq_no = binlog_ptr->next_id();
+    binlog_ptr->add_raw_event(seq_no, BinlogEvent::create_raw(logevent_id, type, BinlogEvent::Flags::Rewrite, storer),
+                              std::move(promise));
+    return seq_no;
+  }
+
+  template <class BinlogT>
+  static uint64 erase(const BinlogT &binlog_ptr, uint64 logevent_id, Promise<> promise = Promise<>()) {
+    auto seq_no = binlog_ptr->next_id();
+    binlog_ptr->add_raw_event(seq_no,
+                              BinlogEvent::create_raw(logevent_id, BinlogEvent::ServiceTypes::Empty,
+                                                      BinlogEvent::Flags::Rewrite, EmptyStorer()),
+                              std::move(promise));
+    return seq_no;
+  }
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/binlog/BinlogInterface.h b/libs/tdlib/td/tddb/td/db/binlog/BinlogInterface.h
new file mode 100644
index 0000000000..2360f3c480
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/binlog/BinlogInterface.h
@@ -0,0 +1,51 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/db/binlog/BinlogEvent.h"
+#include "td/db/DbKey.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+
+namespace td {
+class BinlogInterface {
+ public:
+  BinlogInterface() = default;
+  BinlogInterface(const BinlogInterface &) = delete;
+  BinlogInterface &operator=(const BinlogInterface &) = delete;
+  BinlogInterface(BinlogInterface &&) = delete;
+  BinlogInterface &operator=(BinlogInterface &&) = delete;
+  virtual ~BinlogInterface() = default;
+
+  void close(Promise<> promise = {}) {
+    close_impl(std::move(promise));
+  }
+  void close_and_destroy(Promise<> promise = {}) {
+    close_and_destroy_impl(std::move(promise));
+  }
+  void add_raw_event(uint64 id, BufferSlice &&raw_event, Promise<> promise = Promise<>()) {
+    add_raw_event_impl(id, std::move(raw_event), std::move(promise));
+  }
+  void lazy_sync(Promise<> promise = Promise<>()) {
+    add_raw_event_impl(next_id(), BufferSlice(), std::move(promise));
+  }
+  virtual void force_sync(Promise<> promise) = 0;
+  virtual void force_flush() = 0;
+  virtual void change_key(DbKey db_key, Promise<> promise = Promise<>()) = 0;
+
+  virtual uint64 next_id() = 0;
+  virtual uint64 next_id(int32 shift) = 0;
+
+ protected:
+  virtual void close_impl(Promise<> promise) = 0;
+  virtual void close_and_destroy_impl(Promise<> promise) = 0;
+  virtual void add_raw_event_impl(uint64 id, BufferSlice &&raw_event, Promise<> promise) = 0;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/binlog/ConcurrentBinlog.cpp b/libs/tdlib/td/tddb/td/db/binlog/ConcurrentBinlog.cpp
new file mode 100644
index 0000000000..aaf07f2967
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/binlog/ConcurrentBinlog.cpp
@@ -0,0 +1,203 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/db/binlog/ConcurrentBinlog.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/OrderedEventsProcessor.h"
+#include "td/utils/Time.h"
+
+#include <map>
+
+namespace td {
+namespace detail {
+class BinlogActor : public Actor {
+ public:
+  BinlogActor(std::unique_ptr<Binlog> binlog, uint64 seq_no) : binlog_(std::move(binlog)), processor_(seq_no) {
+  }
+  void close(Promise<> promise) {
+    binlog_->close().ensure();
+    promise.set_value(Unit());
+    LOG(INFO) << "close: done";
+    stop();
+  }
+  void close_and_destroy(Promise<> promise) {
+    binlog_->close_and_destroy().ensure();
+    promise.set_value(Unit());
+    LOG(INFO) << "close_and_destroy: done";
+    stop();
+  }
+
+  struct Event {
+    BufferSlice raw_event;
+    Promise<> sync_promise;
+  };
+  void add_raw_event(uint64 seq_no, BufferSlice &&raw_event, Promise<> &&promise) {
+    processor_.add(seq_no, Event{std::move(raw_event), std::move(promise)}, [&](uint64 id, Event &&event) {
+      if (!event.raw_event.empty()) {
+        do_add_raw_event(std::move(event.raw_event));
+      }
+      do_lazy_sync(std::move(event.sync_promise));
+    });
+    flush_immediate_sync();
+    try_flush();
+  }
+
+  void force_sync(Promise<> &&promise) {
+    auto seq_no = processor_.max_unfinished_seq_no();
+    if (processor_.max_finished_seq_no() == seq_no) {
+      do_immediate_sync(std::move(promise));
+    } else {
+      immediate_sync_promises_.emplace(seq_no, std::move(promise));
+    }
+  }
+
+  void force_flush() {
+    // TODO: use same logic as in force_sync
+    binlog_->flush();
+    flush_flag_ = false;
+  }
+
+  void change_key(DbKey db_key, Promise<> promise) {
+    binlog_->change_key(std::move(db_key));
+    promise.set_value(Unit());
+  }
+
+ private:
+  std::unique_ptr<Binlog> binlog_;
+
+  OrderedEventsProcessor<Event> processor_;
+
+  std::multimap<uint64, Promise<>> immediate_sync_promises_;
+  std::vector<Promise<>> sync_promises_;
+  bool force_sync_flag_ = false;
+  bool lazy_sync_flag_ = false;
+  bool flush_flag_ = false;
+  double wakeup_at_ = 0;
+
+  static constexpr int32 FLUSH_TIMEOUT = 1;  // 1s
+
+  void wakeup_after(double after) {
+    auto now = Time::now_cached();
+    wakeup_at(now + after);
+  }
+
+  void wakeup_at(double at) {
+    if (wakeup_at_ == 0 || wakeup_at_ > at) {
+      wakeup_at_ = at;
+      set_timeout_at(wakeup_at_);
+    }
+  }
+
+  void do_add_raw_event(BufferSlice &&raw_event) {
+    binlog_->add_raw_event(std::move(raw_event));
+  }
+
+  void try_flush() {
+    auto need_flush_since = binlog_->need_flush_since();
+    auto now = Time::now_cached();
+    if (now > need_flush_since + FLUSH_TIMEOUT - 1e-9) {
+      binlog_->flush();
+    } else {
+      if (!force_sync_flag_) {
+        flush_flag_ = true;
+        wakeup_at(need_flush_since + FLUSH_TIMEOUT);
+      }
+    }
+  }
+
+  void flush_immediate_sync() {
+    auto seq_no = processor_.max_finished_seq_no();
+    for (auto it = immediate_sync_promises_.begin(), end = immediate_sync_promises_.end();
+         it != end && it->first <= seq_no; it = immediate_sync_promises_.erase(it)) {
+      do_immediate_sync(std::move(it->second));
+    }
+  }
+
+  void do_immediate_sync(Promise<> &&promise) {
+    if (promise) {
+      sync_promises_.emplace_back(std::move(promise));
+    }
+    if (!force_sync_flag_) {
+      force_sync_flag_ = true;
+      wakeup_after(0.003);
+    }
+  }
+
+  void do_lazy_sync(Promise<> &&promise) {
+    if (!promise) {
+      return;
+    }
+    sync_promises_.emplace_back(std::move(promise));
+    if (!lazy_sync_flag_ && !force_sync_flag_) {
+      wakeup_after(30);
+      lazy_sync_flag_ = true;
+    }
+  }
+
+  void timeout_expired() override {
+    bool need_sync = lazy_sync_flag_ || force_sync_flag_;
+    lazy_sync_flag_ = false;
+    force_sync_flag_ = false;
+    bool need_flush = flush_flag_;
+    flush_flag_ = false;
+    wakeup_at_ = 0;
+    if (need_sync) {
+      binlog_->sync();
+      // LOG(ERROR) << "BINLOG SYNC";
+      for (auto &promise : sync_promises_) {
+        promise.set_value(Unit());
+      }
+      sync_promises_.clear();
+    } else if (need_flush) {
+      try_flush();
+      // LOG(ERROR) << "BINLOG FLUSH";
+    }
+  }
+};
+}  // namespace detail
+
+ConcurrentBinlog::ConcurrentBinlog() = default;
+ConcurrentBinlog::~ConcurrentBinlog() = default;
+ConcurrentBinlog::ConcurrentBinlog(std::unique_ptr<Binlog> binlog, int scheduler_id) {
+  init_impl(std::move(binlog), scheduler_id);
+}
+
+Result<BinlogInfo> ConcurrentBinlog::init(string path, const Callback &callback, DbKey db_key, DbKey old_db_key,
+                                          int scheduler_id) {
+  auto binlog = std::make_unique<Binlog>();
+  TRY_STATUS(binlog->init(std::move(path), callback, std::move(db_key), std::move(old_db_key)));
+  auto info = binlog->get_info();
+  init_impl(std::move(binlog), scheduler_id);
+  return info;
+}
+
+void ConcurrentBinlog::init_impl(std::unique_ptr<Binlog> binlog, int32 scheduler_id) {
+  path_ = binlog->get_path().str();
+  last_id_ = binlog->peek_next_id();
+  binlog_actor_ =
+      create_actor_on_scheduler<detail::BinlogActor>("Binlog " + path_, scheduler_id, std::move(binlog), last_id_);
+}
+
+void ConcurrentBinlog::close_impl(Promise<> promise) {
+  send_closure(std::move(binlog_actor_), &detail::BinlogActor::close, std::move(promise));
+}
+void ConcurrentBinlog::close_and_destroy_impl(Promise<> promise) {
+  send_closure(std::move(binlog_actor_), &detail::BinlogActor::close_and_destroy, std::move(promise));
+}
+void ConcurrentBinlog::add_raw_event_impl(uint64 id, BufferSlice &&raw_event, Promise<> promise) {
+  send_closure(binlog_actor_, &detail::BinlogActor::add_raw_event, id, std::move(raw_event), std::move(promise));
+}
+void ConcurrentBinlog::force_sync(Promise<> promise) {
+  send_closure(binlog_actor_, &detail::BinlogActor::force_sync, std::move(promise));
+}
+void ConcurrentBinlog::force_flush() {
+  send_closure(binlog_actor_, &detail::BinlogActor::force_flush);
+}
+void ConcurrentBinlog::change_key(DbKey db_key, Promise<> promise) {
+  send_closure(binlog_actor_, &detail::BinlogActor::change_key, std::move(db_key), std::move(promise));
+}
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/binlog/ConcurrentBinlog.h b/libs/tdlib/td/tddb/td/db/binlog/ConcurrentBinlog.h
new file mode 100644
index 0000000000..ce77a78a84
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/binlog/ConcurrentBinlog.h
@@ -0,0 +1,68 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/db/binlog/Binlog.h"
+#include "td/db/binlog/BinlogInterface.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <atomic>
+#include <functional>
+
+namespace td {
+
+namespace detail {
+class BinlogActor;
+}  // namespace detail
+
+class ConcurrentBinlog : public BinlogInterface {
+ public:
+  using Callback = std::function<void(const BinlogEvent &)>;
+  Result<BinlogInfo> init(string path, const Callback &callback, DbKey db_key = DbKey::empty(),
+                          DbKey old_db_key = DbKey::empty(), int scheduler_id = -1) TD_WARN_UNUSED_RESULT;
+
+  ConcurrentBinlog();
+  explicit ConcurrentBinlog(std::unique_ptr<Binlog> binlog, int scheduler_id = -1);
+  ConcurrentBinlog(const ConcurrentBinlog &other) = delete;
+  ConcurrentBinlog &operator=(const ConcurrentBinlog &other) = delete;
+  ConcurrentBinlog(ConcurrentBinlog &&other) = delete;
+  ConcurrentBinlog &operator=(ConcurrentBinlog &&other) = delete;
+  ~ConcurrentBinlog() override;
+
+  void force_sync(Promise<> promise) override;
+  void force_flush() override;
+  void change_key(DbKey db_key, Promise<> promise) override;
+
+  uint64 next_id() override {
+    return last_id_.fetch_add(1, std::memory_order_relaxed);
+  }
+  uint64 next_id(int32 shift) override {
+    return last_id_.fetch_add(shift, std::memory_order_relaxed);
+  }
+
+  CSlice get_path() const {
+    return path_;
+  }
+
+ private:
+  void init_impl(std::unique_ptr<Binlog> binlog, int scheduler_id);
+  void close_impl(Promise<> promise) override;
+  void close_and_destroy_impl(Promise<> promise) override;
+  void add_raw_event_impl(uint64 id, BufferSlice &&raw_event, Promise<> promise) override;
+
+  ActorOwn<detail::BinlogActor> binlog_actor_;
+  string path_;
+  std::atomic<uint64> last_id_;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/binlog/binlog_dump.cpp b/libs/tdlib/td/tddb/td/db/binlog/binlog_dump.cpp
new file mode 100644
index 0000000000..a8b8bf9e1b
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/binlog/binlog_dump.cpp
@@ -0,0 +1,53 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/db/binlog/Binlog.h"
+
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+
+#include <cstdio>
+#include <map>
+
+int main(int argc, char *argv[]) {
+  if (argc < 2) {
+    std::fprintf(stderr, "Usage: binlog_dump <binlog_file_name>\n");
+    return 1;
+  }
+
+  struct Info {
+    std::size_t full_size = 0;
+    std::size_t compressed_size = 0;
+  };
+  std::map<td::uint64, Info> info;
+
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR));
+  td::Binlog binlog;
+  binlog
+      .init(argv[1],
+            [&](auto &event) {
+              info[0].compressed_size += event.raw_event_.size();
+              info[event.type_].compressed_size += event.raw_event_.size();
+            },
+            td::DbKey::empty(), td::DbKey::empty(), -1,
+            [&](auto &event) mutable {
+              info[0].full_size += event.raw_event_.size();
+              info[event.type_].full_size += event.raw_event_.size();
+              LOG(PLAIN) << "LogEvent[" << td::tag("id", td::format::as_hex(event.id_)) << td::tag("type", event.type_)
+                         << td::tag("flags", event.flags_) << td::tag("data", td::format::escaped(event.data_))
+                         << "]\n";
+            })
+      .ensure();
+
+  for (auto &it : info) {
+    LOG(ERROR) << td::tag("handler", td::format::as_hex(it.first))
+               << td::tag("full_size", td::format::as_size(it.second.full_size))
+               << td::tag("compressed_size", td::format::as_size(it.second.compressed_size));
+  }
+
+  return 0;
+}
diff --git a/libs/tdlib/td/tddb/td/db/binlog/detail/BinlogEventsBuffer.cpp b/libs/tdlib/td/tddb/td/db/binlog/detail/BinlogEventsBuffer.cpp
new file mode 100644
index 0000000000..b7ddc98ff1
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/binlog/detail/BinlogEventsBuffer.cpp
@@ -0,0 +1,39 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/db/binlog/detail/BinlogEventsBuffer.h"
+
+#include <algorithm>
+
+namespace td {
+namespace detail {
+void BinlogEventsBuffer::add_event(BinlogEvent &&event) {
+  total_events_++;
+  if ((event.flags_ & BinlogEvent::Flags::Partial) == 0) {
+    auto it = std::find(ids_.begin(), ids_.end(), event.id_);
+    if (it != ids_.end()) {
+      auto &to_event = events_[it - ids_.begin()];
+      size_ -= to_event.size_;
+      to_event = std::move(event);
+      size_ += to_event.size_;
+      return;
+    }
+  }
+  ids_.push_back(event.id_);
+  size_ += event.size_;
+  events_.push_back(std::move(event));
+}
+bool BinlogEventsBuffer::need_flush() const {
+  return total_events_ > 5000 || ids_.size() > 100;
+}
+void BinlogEventsBuffer::clear() {
+  ids_.clear();
+  events_.clear();
+  total_events_ = 0;
+  size_ = 0;
+}
+}  // namespace detail
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/binlog/detail/BinlogEventsBuffer.h b/libs/tdlib/td/tddb/td/db/binlog/detail/BinlogEventsBuffer.h
new file mode 100644
index 0000000000..dcd6d7c1b3
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/binlog/detail/BinlogEventsBuffer.h
@@ -0,0 +1,47 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/db/binlog/BinlogEvent.h"
+
+#include "td/utils/common.h"
+
+namespace td {
+namespace detail {
+class BinlogEventsBuffer {
+ public:
+  void add_event(BinlogEvent &&event);
+
+  bool need_flush() const;
+
+  template <class CallbackT>
+  void flush(CallbackT &&callback) {
+    for (size_t i = 0; i < ids_.size(); i++) {
+      auto &event = events_[i];
+      if (i + 1 != ids_.size() && (event.flags_ & BinlogEvent::Flags::Partial) == 0) {
+        callback(BinlogEvent(BinlogEvent::create_raw(event.id_, event.type_, event.flags_ | BinlogEvent::Flags::Partial,
+                                                     create_storer(event.data_))));
+      } else {
+        callback(std::move(event));
+      }
+    }
+    clear();
+  }
+  size_t size() const {
+    return size_;
+  }
+
+ private:
+  vector<uint64> ids_;
+  vector<BinlogEvent> events_;
+  size_t total_events_{0};
+  size_t size_{0};
+
+  void do_event(BinlogEvent &&event);
+  void clear();
+};
+}  // namespace detail
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/binlog/detail/BinlogEventsProcessor.cpp b/libs/tdlib/td/tddb/td/db/binlog/detail/BinlogEventsProcessor.cpp
new file mode 100644
index 0000000000..50ad91bff8
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/binlog/detail/BinlogEventsProcessor.cpp
@@ -0,0 +1,70 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/db/binlog/detail/BinlogEventsProcessor.h"
+
+#include "td/utils/logging.h"
+
+#include <algorithm>
+
+namespace td {
+namespace detail {
+void BinlogEventsProcessor::do_event(BinlogEvent &&event) {
+  offset_ = event.offset_;
+  auto fixed_id = event.id_ * 2;
+  if ((event.flags_ & BinlogEvent::Flags::Rewrite) && !ids_.empty() && ids_.back() >= fixed_id) {
+    auto it = std::lower_bound(ids_.begin(), ids_.end(), fixed_id);
+    if (it == ids_.end() || *it != fixed_id) {
+      LOG(FATAL) << "Ignore rewrite logevent";
+      return;
+    }
+    auto pos = it - ids_.begin();
+    total_raw_events_size_ -= static_cast<int64>(events_[pos].raw_event_.size());
+    if (event.type_ == BinlogEvent::ServiceTypes::Empty) {
+      *it += 1;
+      empty_events_++;
+      events_[pos].clear();
+    } else {
+      event.flags_ &= ~BinlogEvent::Flags::Rewrite;
+      total_raw_events_size_ += static_cast<int64>(event.raw_event_.size());
+      events_[pos] = std::move(event);
+    }
+  } else if (event.type_ == BinlogEvent::ServiceTypes::Empty) {
+    // just skip this event
+  } else {
+    CHECK(ids_.empty() || ids_.back() < fixed_id);
+    last_id_ = event.id_;
+    total_raw_events_size_ += static_cast<int64>(event.raw_event_.size());
+    total_events_++;
+    ids_.push_back(fixed_id);
+    events_.emplace_back(std::move(event));
+  }
+
+  if (total_events_ > 10 && empty_events_ * 4 > total_events_ * 3) {
+    compactify();
+  }
+}
+
+void BinlogEventsProcessor::compactify() {
+  CHECK(ids_.size() == events_.size());
+  auto ids_from = ids_.begin();
+  auto ids_to = ids_from;
+  auto events_from = events_.begin();
+  auto events_to = events_from;
+  for (; ids_from != ids_.end(); ids_from++, events_from++) {
+    if ((*ids_from & 1) == 0) {
+      *ids_to++ = *ids_from;
+      *events_to++ = std::move(*events_from);
+    }
+  }
+  ids_.erase(ids_to, ids_.end());
+  events_.erase(events_to, events_.end());
+  total_events_ = ids_.size();
+  empty_events_ = 0;
+  CHECK(ids_.size() == events_.size());
+}
+}  // namespace detail
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/binlog/detail/BinlogEventsProcessor.h b/libs/tdlib/td/tddb/td/db/binlog/detail/BinlogEventsProcessor.h
new file mode 100644
index 0000000000..645f8c50ab
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/binlog/detail/BinlogEventsProcessor.h
@@ -0,0 +1,53 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/db/binlog/BinlogEvent.h"
+
+#include "td/utils/common.h"
+
+namespace td {
+namespace detail {
+class BinlogEventsProcessor {
+ public:
+  void add_event(BinlogEvent &&event) {
+    do_event(std::move(event));
+  }
+
+  template <class CallbackT>
+  void for_each(CallbackT &&callback) {
+    for (size_t i = 0; i < ids_.size(); i++) {
+      if ((ids_[i] & 1) == 0) {
+        callback(events_[i]);
+      }
+    }
+  }
+
+  uint64 last_id() const {
+    return last_id_;
+  }
+  int64 offset() const {
+    return offset_;
+  }
+  int64 total_raw_events_size() const {
+    return total_raw_events_size_;
+  }
+
+ private:
+  // holds (id * 2 + was_deleted)
+  std::vector<uint64> ids_;
+  std::vector<BinlogEvent> events_;
+  size_t total_events_{0};
+  size_t empty_events_{0};
+  uint64 last_id_{0};
+  int64 offset_{0};
+  int64 total_raw_events_size_{0};
+
+  void do_event(BinlogEvent &&event);
+  void compactify();
+};
+}  // namespace detail
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/detail/RawSqliteDb.cpp b/libs/tdlib/td/tddb/td/db/detail/RawSqliteDb.cpp
new file mode 100644
index 0000000000..6ee1b45af2
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/detail/RawSqliteDb.cpp
@@ -0,0 +1,39 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/db/detail/RawSqliteDb.h"
+
+#include "sqlite/sqlite3.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/path.h"
+
+namespace td {
+namespace detail {
+Status RawSqliteDb::last_error(sqlite3 *db) {
+  return Status::Error(Slice(sqlite3_errmsg(db)));
+}
+Status RawSqliteDb::destroy(Slice path) {
+  with_db_path(path, [](auto path) { unlink(path).ignore(); });
+  return Status::OK();
+}
+Status RawSqliteDb::last_error() {
+  //If database was corrupted, try to delete it.
+  auto code = sqlite3_errcode(db_);
+  if (code == SQLITE_CORRUPT) {
+    destroy(path_).ignore();
+  }
+
+  return last_error(db_);
+}
+RawSqliteDb::~RawSqliteDb() {
+  auto rc = sqlite3_close(db_);
+  LOG_IF(FATAL, rc != SQLITE_OK) << last_error(db_);
+}
+
+}  // namespace detail
+}  // namespace td
diff --git a/libs/tdlib/td/tddb/td/db/detail/RawSqliteDb.h b/libs/tdlib/td/tddb/td/db/detail/RawSqliteDb.h
new file mode 100644
index 0000000000..801f3b192a
--- /dev/null
+++ b/libs/tdlib/td/tddb/td/db/detail/RawSqliteDb.h
@@ -0,0 +1,51 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+struct sqlite3;
+
+namespace td {
+namespace detail {
+class RawSqliteDb {
+ public:
+  RawSqliteDb(sqlite3 *db, std::string path) : db_(db), path_(std::move(path)) {
+  }
+  RawSqliteDb(const RawSqliteDb &) = delete;
+  RawSqliteDb(RawSqliteDb &&) = delete;
+  RawSqliteDb &operator=(const RawSqliteDb &) = delete;
+  RawSqliteDb &operator=(RawSqliteDb &&) = delete;
+  ~RawSqliteDb();
+
+  template <class F>
+  static void with_db_path(Slice main_path, F &&f) {
+    f(PSLICE() << main_path);
+    f(PSLICE() << main_path << "-journal");
+    f(PSLICE() << main_path << "-shm");
+    f(PSLICE() << main_path << "-wal");
+  }
+  static Status destroy(Slice path) TD_WARN_UNUSED_RESULT;
+
+  sqlite3 *db() {
+    return db_;
+  }
+  CSlice path() const {
+    return path_;
+  }
+
+  Status last_error();
+  static Status last_error(sqlite3 *db);
+
+ private:
+  sqlite3 *db_;
+  std::string path_;
+};
+};  // namespace detail
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/CMakeLists.txt b/libs/tdlib/td/tdnet/CMakeLists.txt
new file mode 100644
index 0000000000..823ed027d6
--- /dev/null
+++ b/libs/tdlib/td/tdnet/CMakeLists.txt
@@ -0,0 +1,54 @@
+cmake_minimum_required(VERSION 3.0.2 FATAL_ERROR)
+
+if (NOT OPENSSL_FOUND)
+  find_package(OpenSSL REQUIRED)
+  find_package(ZLIB REQUIRED)
+endif()
+
+#SOURCE SETS
+set(TDNET_SOURCE
+  td/net/GetHostByNameActor.cpp
+  td/net/HttpChunkedByteFlow.cpp
+  td/net/HttpConnectionBase.cpp
+  td/net/HttpContentLengthByteFlow.cpp
+  td/net/HttpFile.cpp
+  td/net/HttpInboundConnection.cpp
+  td/net/HttpOutboundConnection.cpp
+  td/net/HttpQuery.cpp
+  td/net/HttpReader.cpp
+  td/net/Socks5.cpp
+  td/net/SslFd.cpp
+  td/net/TcpListener.cpp
+  td/net/Wget.cpp
+
+  td/net/GetHostByNameActor.h
+  td/net/HttpChunkedByteFlow.h
+  td/net/HttpConnectionBase.h
+  td/net/HttpContentLengthByteFlow.h
+  td/net/HttpFile.h
+  td/net/HttpHeaderCreator.h
+  td/net/HttpInboundConnection.h
+  td/net/HttpOutboundConnection.h
+  td/net/HttpQuery.h
+  td/net/HttpReader.h
+  td/net/NetStats.h
+  td/net/Socks5.h
+  td/net/SslFd.h
+  td/net/TcpListener.h
+  td/net/Wget.h
+)
+
+#RULES
+#LIBRARIES
+
+add_library(tdnet STATIC ${TDNET_SOURCE})
+target_include_directories(tdnet PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>)
+target_include_directories(tdnet SYSTEM PUBLIC $<BUILD_INTERFACE:${OPENSSL_INCLUDE_DIR}>)
+target_link_libraries(tdnet PUBLIC tdutils tdactor ${OPENSSL_LIBRARIES} PRIVATE ${CMAKE_DL_LIBS} ${ZLIB_LIBRARIES})
+
+install(TARGETS tdnet EXPORT TdTargets
+  LIBRARY DESTINATION lib
+  ARCHIVE DESTINATION lib
+  RUNTIME DESTINATION bin
+  INCLUDES DESTINATION include
+)
diff --git a/libs/tdlib/td/tdnet/td/net/GetHostByNameActor.cpp b/libs/tdlib/td/tdnet/td/net/GetHostByNameActor.cpp
new file mode 100644
index 0000000000..b6cdcca0f0
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/GetHostByNameActor.cpp
@@ -0,0 +1,48 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/net/GetHostByNameActor.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/Time.h"
+
+namespace td {
+GetHostByNameActor::GetHostByNameActor(int32 ok_timeout, int32 error_timeout)
+    : ok_timeout_(ok_timeout), error_timeout_(error_timeout) {
+}
+
+void GetHostByNameActor::run(std::string host, int port, td::Promise<td::IPAddress> promise) {
+  auto r_ip = load_ip(std::move(host), port);
+  promise.set_result(std::move(r_ip));
+}
+
+Result<td::IPAddress> GetHostByNameActor::load_ip(string host, int port) {
+  auto &value = cache_.emplace(host, Value{{}, 0}).first->second;
+  auto begin_time = td::Time::now();
+  if (value.expire_at > begin_time) {
+    auto ip = value.ip.clone();
+    if (ip.is_ok()) {
+      ip.ok_ref().set_port(port);
+      CHECK(ip.ok().get_port() == port);
+    }
+    return ip;
+  }
+
+  td::IPAddress ip;
+  auto status = ip.init_host_port(host, port);
+  auto end_time = td::Time::now();
+  LOG(WARNING) << "Init host = " << host << ", port = " << port << " in " << end_time - begin_time << " seconds to "
+               << ip;
+
+  if (status.is_ok()) {
+    value = Value{ip, end_time + ok_timeout_};
+    return ip;
+  } else {
+    value = Value{status.clone(), end_time + error_timeout_};
+    return std::move(status);
+  }
+}
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/GetHostByNameActor.h b/libs/tdlib/td/tdnet/td/net/GetHostByNameActor.h
new file mode 100644
index 0000000000..b352a05d18
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/GetHostByNameActor.h
@@ -0,0 +1,35 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/utils/port/IPAddress.h"
+#include "td/utils/Status.h"
+
+#include <unordered_map>
+
+namespace td {
+class GetHostByNameActor final : public td::Actor {
+ public:
+  explicit GetHostByNameActor(int32 ok_timeout = CACHE_TIME, int32 error_timeout = ERROR_CACHE_TIME);
+  void run(std::string host, int port, td::Promise<td::IPAddress> promise);
+
+ private:
+  struct Value {
+    Result<td::IPAddress> ip;
+    double expire_at;
+  };
+  std::unordered_map<string, Value> cache_;
+  static constexpr int32 CACHE_TIME = 60 * 29;       // 29 minutes
+  static constexpr int32 ERROR_CACHE_TIME = 60 * 5;  // 5 minutes
+
+  int32 ok_timeout_;
+  int32 error_timeout_;
+  Result<td::IPAddress> load_ip(string host, int port) TD_WARN_UNUSED_RESULT;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpChunkedByteFlow.cpp b/libs/tdlib/td/tdnet/td/net/HttpChunkedByteFlow.cpp
new file mode 100644
index 0000000000..2edd225bfa
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpChunkedByteFlow.cpp
@@ -0,0 +1,83 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/net/HttpChunkedByteFlow.h"
+
+#include "td/utils/find_boundary.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+void HttpChunkedByteFlow::loop() {
+  bool was_updated = false;
+  size_t need_size;
+  while (true) {
+    if (state_ == ReadChunkLength) {
+      bool ok = find_boundary(input_->clone(), "\r\n", len_);
+      if (len_ > 10) {
+        return finish(Status::Error(PSLICE() << "Too long length in chunked "
+                                             << input_->cut_head(len_).move_as_buffer_slice().as_slice()));
+      }
+      if (!ok) {
+        need_size = input_->size() + 1;
+        break;
+      }
+      auto s_len = input_->cut_head(len_).move_as_buffer_slice();
+      input_->advance(2);
+      len_ = hex_to_integer<size_t>(s_len.as_slice());
+      if (len_ > MAX_CHUNK_SIZE) {
+        return finish(Status::Error(PSLICE() << "Invalid chunk size " << tag("size", len_)));
+      }
+      save_len_ = len_;
+      state_ = ReadChunkContent;
+    }
+
+    auto size = input_->size();
+    auto ready = min(len_, size);
+    need_size = min(MIN_UPDATE_SIZE, len_ + 2);
+    if (size < need_size) {
+      break;
+    }
+    total_size_ += ready;
+    uncommited_size_ += ready;
+    if (total_size_ > MAX_SIZE) {
+      return finish(Status::Error(PSLICE() << "Too big query " << tag("size", input_->size())));
+    }
+
+    output_.append(input_->cut_head(ready));
+    len_ -= ready;
+    if (uncommited_size_ >= MIN_UPDATE_SIZE) {
+      uncommited_size_ = 0;
+      was_updated = true;
+    }
+
+    if (len_ == 0) {
+      if (input_->size() < 2) {
+        need_size = 2;
+        break;
+      }
+      input_->cut_head(2);
+      total_size_ += 2;
+      if (save_len_ == 0) {
+        return finish(Status::OK());
+      }
+      state_ = ReadChunkLength;
+      len_ = 0;
+    }
+  }
+  if (was_updated) {
+    on_output_updated();
+  }
+  if (!is_input_active_) {
+    return finish(Status::Error("Unexpected end of stream"));
+  }
+  set_need_size(need_size);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpChunkedByteFlow.h b/libs/tdlib/td/tdnet/td/net/HttpChunkedByteFlow.h
new file mode 100644
index 0000000000..9c62c3368e
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpChunkedByteFlow.h
@@ -0,0 +1,28 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/ByteFlow.h"
+
+namespace td {
+
+class HttpChunkedByteFlow final : public ByteFlowBase {
+ public:
+  void loop() override;
+
+ private:
+  static constexpr int MAX_CHUNK_SIZE = 15 << 20;  // some reasonable limit
+  static constexpr int MAX_SIZE = 150 << 20;       // some reasonable limit
+  static constexpr size_t MIN_UPDATE_SIZE = 1 << 14;
+  enum { ReadChunkLength, ReadChunkContent, OK } state_ = ReadChunkLength;
+  size_t len_ = 0;
+  size_t save_len_;
+  size_t total_size_ = 0;
+  size_t uncommited_size_ = 0;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpConnectionBase.cpp b/libs/tdlib/td/tdnet/td/net/HttpConnectionBase.cpp
new file mode 100644
index 0000000000..087ee5b790
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpConnectionBase.cpp
@@ -0,0 +1,153 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/net/HttpConnectionBase.h"
+
+#include "td/actor/actor.h"
+
+#include "td/net/HttpHeaderCreator.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+
+namespace td {
+namespace detail {
+
+HttpConnectionBase::HttpConnectionBase(State state, FdProxy fd, size_t max_post_size, size_t max_files,
+                                       int32 idle_timeout)
+    : state_(state)
+    , stream_connection_(std::move(fd))
+    , max_post_size_(max_post_size)
+    , max_files_(max_files)
+    , idle_timeout_(idle_timeout) {
+  CHECK(state_ != State::Close);
+}
+
+void HttpConnectionBase::live_event() {
+  if (idle_timeout_ != 0) {
+    set_timeout_in(idle_timeout_);
+  }
+}
+
+void HttpConnectionBase::start_up() {
+  stream_connection_.get_fd().set_observer(this);
+  subscribe(stream_connection_.get_fd());
+  reader_.init(&stream_connection_.input_buffer(), max_post_size_, max_files_);
+  if (state_ == State::Read) {
+    current_query_ = make_unique<HttpQuery>();
+  }
+  live_event();
+  yield();
+}
+void HttpConnectionBase::tear_down() {
+  unsubscribe_before_close(stream_connection_.get_fd());
+  stream_connection_.close();
+}
+
+void HttpConnectionBase::write_next(BufferSlice buffer) {
+  CHECK(state_ == State::Write);
+  stream_connection_.output_buffer().append(std::move(buffer));
+  loop();
+}
+
+void HttpConnectionBase::write_ok() {
+  CHECK(state_ == State::Write);
+  current_query_ = make_unique<HttpQuery>();
+  state_ = State::Read;
+  live_event();
+  loop();
+}
+
+void HttpConnectionBase::write_error(Status error) {
+  CHECK(state_ == State::Write);
+  LOG(WARNING) << "Close http connection: " << error;
+  state_ = State::Close;
+  loop();
+}
+
+void HttpConnectionBase::timeout_expired() {
+  LOG(INFO) << "Idle timeout expired";
+
+  if (stream_connection_.need_flush_write()) {
+    on_error(Status::Error("Write timeout expired"));
+  } else if (state_ == State::Read) {
+    on_error(Status::Error("Read timeout expired"));
+  }
+
+  stop();
+}
+void HttpConnectionBase::loop() {
+  if (can_read(stream_connection_)) {
+    LOG(DEBUG) << "Can read from the connection";
+    auto r = stream_connection_.flush_read();
+    if (r.is_error()) {
+      if (!begins_with(r.error().message(), "SSL error {336134278")) {  // if error is not yet outputed
+        LOG(INFO) << "flush_read error: " << r.error();
+      }
+      on_error(Status::Error(r.error().public_message()));
+      return stop();
+    }
+  }
+
+  // TODO: read_next even when state_ == State::Write
+
+  bool want_read = false;
+  if (state_ == State::Read) {
+    auto res = reader_.read_next(current_query_.get());
+    if (res.is_error()) {
+      live_event();
+      state_ = State::Write;
+      LOG(INFO) << res.error();
+      HttpHeaderCreator hc;
+      hc.init_status_line(res.error().code());
+      hc.set_content_size(0);
+      stream_connection_.output_buffer().append(hc.finish().ok());
+      close_after_write_ = true;
+      on_error(Status::Error(res.error().public_message()));
+    } else if (res.ok() == 0) {
+      state_ = State::Write;
+      LOG(INFO) << "Send query to handler";
+      live_event();
+      on_query(std::move(current_query_));
+    } else {
+      want_read = true;
+    }
+  }
+
+  if (can_write(stream_connection_)) {
+    LOG(DEBUG) << "Can write to the connection";
+    auto r = stream_connection_.flush_write();
+    if (r.is_error()) {
+      LOG(INFO) << "flush_write error: " << r.error();
+      on_error(Status::Error(r.error().public_message()));
+    }
+    if (close_after_write_ && !stream_connection_.need_flush_write()) {
+      return stop();
+    }
+  }
+
+  if (stream_connection_.get_fd().has_pending_error()) {
+    auto pending_error = stream_connection_.get_pending_error();
+    LOG(INFO) << pending_error;
+    if (!close_after_write_) {
+      on_error(Status::Error(pending_error.public_message()));
+    }
+    state_ = State::Close;
+  }
+  if (can_close(stream_connection_)) {
+    LOG(INFO) << "Can close the connection";
+    state_ = State::Close;
+  }
+  if (state_ == State::Close) {
+    LOG_IF(INFO, stream_connection_.need_flush_write()) << "Close nonempty connection";
+    LOG_IF(INFO, want_read &&
+                     (stream_connection_.input_buffer().size() > 0 || current_query_->type_ != HttpQuery::Type::EMPTY))
+        << "Close connection while reading request/response";
+    return stop();
+  }
+}
+}  // namespace detail
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpConnectionBase.h b/libs/tdlib/td/tdnet/td/net/HttpConnectionBase.h
new file mode 100644
index 0000000000..1d420a3175
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpConnectionBase.h
@@ -0,0 +1,164 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+
+#include "td/net/HttpQuery.h"
+#include "td/net/HttpReader.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/BufferedFd.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+class FdInterface {
+ public:
+  FdInterface() = default;
+  FdInterface(const FdInterface &) = delete;
+  FdInterface &operator=(const FdInterface &) = delete;
+  FdInterface(FdInterface &&) = default;
+  FdInterface &operator=(FdInterface &&) = default;
+  virtual ~FdInterface() = default;
+  virtual const Fd &get_fd() const = 0;
+  virtual Fd &get_fd() = 0;
+  virtual int32 get_flags() const = 0;
+  virtual Status get_pending_error() TD_WARN_UNUSED_RESULT = 0;
+
+  virtual Result<size_t> write(Slice slice) TD_WARN_UNUSED_RESULT = 0;
+  virtual Result<size_t> read(MutableSlice slice) TD_WARN_UNUSED_RESULT = 0;
+
+  virtual void close() = 0;
+  virtual bool empty() const = 0;
+};
+
+template <class FdT>
+class FdToInterface : public FdInterface {
+ public:
+  FdToInterface() = default;
+  explicit FdToInterface(FdT fd) : fd_(std::move(fd)) {
+  }
+
+  const Fd &get_fd() const final {
+    return fd_.get_fd();
+  }
+  Fd &get_fd() final {
+    return fd_.get_fd();
+  }
+  int32 get_flags() const final {
+    return fd_.get_flags();
+  }
+  Status get_pending_error() final TD_WARN_UNUSED_RESULT {
+    return fd_.get_pending_error();
+  }
+
+  Result<size_t> write(Slice slice) final TD_WARN_UNUSED_RESULT {
+    return fd_.write(slice);
+  }
+  Result<size_t> read(MutableSlice slice) final TD_WARN_UNUSED_RESULT {
+    return fd_.read(slice);
+  }
+
+  void close() final {
+    fd_.close();
+  }
+  bool empty() const final {
+    return fd_.empty();
+  }
+
+ private:
+  FdT fd_;
+};
+
+template <class FdT>
+std::unique_ptr<FdInterface> make_fd_interface(FdT fd) {
+  return make_unique<FdToInterface<FdT>>(std::move(fd));
+}
+
+class FdProxy {
+ public:
+  FdProxy() = default;
+  explicit FdProxy(std::unique_ptr<FdInterface> fd) : fd_(std::move(fd)) {
+  }
+
+  const Fd &get_fd() const {
+    return fd_->get_fd();
+  }
+  Fd &get_fd() {
+    return fd_->get_fd();
+  }
+  int32 get_flags() const {
+    return fd_->get_flags();
+  }
+  Status get_pending_error() TD_WARN_UNUSED_RESULT {
+    return fd_->get_pending_error();
+  }
+
+  Result<size_t> write(Slice slice) TD_WARN_UNUSED_RESULT {
+    return fd_->write(slice);
+  }
+  Result<size_t> read(MutableSlice slice) TD_WARN_UNUSED_RESULT {
+    return fd_->read(slice);
+  }
+
+  void close() {
+    fd_->close();
+  }
+  bool empty() const {
+    return fd_->empty();
+  }
+
+ private:
+  std::unique_ptr<FdInterface> fd_;
+};
+
+template <class FdT>
+FdProxy make_fd_proxy(FdT fd) {
+  return FdProxy(make_fd_interface(std::move(fd)));
+}
+
+namespace detail {
+class HttpConnectionBase : public Actor {
+ public:
+  void write_next(BufferSlice buffer);
+  void write_ok();
+  void write_error(Status error);
+
+ protected:
+  enum class State { Read, Write, Close };
+  template <class FdT>
+  HttpConnectionBase(State state, FdT fd, size_t max_post_size, size_t max_files, int32 idle_timeout)
+      : HttpConnectionBase(state, make_fd_proxy(std::move(fd)), max_post_size, max_files, idle_timeout) {
+  }
+  HttpConnectionBase(State state, FdProxy fd, size_t max_post_size, size_t max_files, int32 idle_timeout);
+
+ private:
+  using StreamConnection = BufferedFd<FdProxy>;
+  State state_;
+  StreamConnection stream_connection_;
+  size_t max_post_size_;
+  size_t max_files_;
+  int32 idle_timeout_;
+  HttpReader reader_;
+  HttpQueryPtr current_query_;
+  bool close_after_write_ = false;
+
+  void live_event();
+
+  void start_up() override;
+  void tear_down() override;
+  void timeout_expired() override;
+  void loop() override;
+
+  virtual void on_query(HttpQueryPtr) = 0;
+  virtual void on_error(Status error) = 0;
+};
+}  // namespace detail
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpContentLengthByteFlow.cpp b/libs/tdlib/td/tdnet/td/net/HttpContentLengthByteFlow.cpp
new file mode 100644
index 0000000000..ea299b3993
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpContentLengthByteFlow.cpp
@@ -0,0 +1,34 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/net/HttpContentLengthByteFlow.h"
+
+#include "td/utils/Status.h"
+
+namespace td {
+
+void HttpContentLengthByteFlow::loop() {
+  auto ready_size = input_->size();
+  if (ready_size > len_) {
+    ready_size = len_;
+  }
+  auto need_size = min(MIN_UPDATE_SIZE, len_);
+  if (ready_size < need_size) {
+    set_need_size(need_size);
+    return;
+  }
+  output_.append(input_->cut_head(ready_size));
+  len_ -= ready_size;
+  if (len_ == 0) {
+    return finish(Status::OK());
+  }
+  if (!is_input_active_) {
+    return finish(Status::Error("Unexpected end of stream"));
+  }
+  on_output_updated();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpContentLengthByteFlow.h b/libs/tdlib/td/tdnet/td/net/HttpContentLengthByteFlow.h
new file mode 100644
index 0000000000..18f86abdb0
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpContentLengthByteFlow.h
@@ -0,0 +1,25 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/ByteFlow.h"
+
+namespace td {
+
+class HttpContentLengthByteFlow final : public ByteFlowBase {
+ public:
+  HttpContentLengthByteFlow() = default;
+  explicit HttpContentLengthByteFlow(size_t len) : len_(len) {
+  }
+  void loop() override;
+
+ private:
+  static constexpr size_t MIN_UPDATE_SIZE = 1 << 14;
+  size_t len_ = 0;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpFile.cpp b/libs/tdlib/td/tdnet/td/net/HttpFile.cpp
new file mode 100644
index 0000000000..b4f6e6d16b
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpFile.cpp
@@ -0,0 +1,25 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/net/HttpFile.h"
+
+#include "td/net/HttpReader.h"
+
+#include "td/utils/format.h"
+
+namespace td {
+
+HttpFile::~HttpFile() {
+  if (!temp_file_name.empty()) {
+    HttpReader::delete_temp_file(temp_file_name);
+  }
+}
+
+StringBuilder &operator<<(StringBuilder &sb, const HttpFile &file) {
+  return sb << tag("name", file.name) << tag("size", file.size);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpFile.h b/libs/tdlib/td/tdnet/td/net/HttpFile.h
new file mode 100644
index 0000000000..6f35843060
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpFile.h
@@ -0,0 +1,49 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/StringBuilder.h"
+
+namespace td {
+
+class HttpFile {
+ public:
+  string field_name;
+  string name;
+  string content_type;
+  int64 size;
+  string temp_file_name;
+
+  HttpFile(string field_name, string name, string content_type, int64 size, string temp_file_name)
+      : field_name(std::move(field_name))
+      , name(std::move(name))
+      , content_type(std::move(content_type))
+      , size(size)
+      , temp_file_name(std::move(temp_file_name)) {
+  }
+
+  HttpFile(const HttpFile &) = delete;
+  HttpFile &operator=(const HttpFile &) = delete;
+
+  HttpFile(HttpFile &&other)
+      : field_name(std::move(other.field_name))
+      , name(std::move(other.name))
+      , content_type(std::move(other.content_type))
+      , size(other.size)
+      , temp_file_name(std::move(other.temp_file_name)) {
+    other.temp_file_name.clear();
+  }
+
+  HttpFile &operator=(HttpFile &&) = delete;
+
+  ~HttpFile();
+};
+
+StringBuilder &operator<<(StringBuilder &sb, const HttpFile &file);
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpHeaderCreator.h b/libs/tdlib/td/tdnet/td/net/HttpHeaderCreator.h
new file mode 100644
index 0000000000..d3e84e5dbf
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpHeaderCreator.h
@@ -0,0 +1,139 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+
+namespace td {
+
+class HttpHeaderCreator {
+ public:
+  static constexpr size_t MAX_HEADER = 4096;
+  HttpHeaderCreator() : sb_({header_, MAX_HEADER}) {
+  }
+  void init_ok() {
+    sb_ = StringBuilder({header_, MAX_HEADER});
+    sb_ << "HTTP/1.1 200 OK\r\n";
+  }
+  void init_get(Slice url) {
+    sb_ = StringBuilder({header_, MAX_HEADER});
+    sb_ << "GET " << url << " HTTP/1.1\r\n";
+  }
+  void init_post(Slice url) {
+    sb_ = StringBuilder({header_, MAX_HEADER});
+    sb_ << "POST " << url << " HTTP/1.1\r\n";
+  }
+  void init_error(int code, Slice reason) {
+    sb_ = StringBuilder({header_, MAX_HEADER});
+    sb_ << "HTTP/1.1 " << code << " " << reason << "\r\n";
+  }
+  void init_status_line(int http_status_code) {
+    sb_ = StringBuilder({header_, MAX_HEADER});
+    sb_ << "HTTP/1.1 " << http_status_code << " " << get_status_line(http_status_code) << "\r\n";
+  }
+  void add_header(Slice key, Slice value) {
+    sb_ << key << ": " << value << "\r\n";
+  }
+  void set_content_type(Slice type) {
+    add_header("Content-Type", type);
+  }
+  void set_content_size(size_t size) {
+    add_header("Content-Length", to_string(size));
+  }
+  void set_keep_alive() {
+    add_header("Connection", "keep-alive");
+  }
+
+  Result<Slice> finish(Slice content = {}) TD_WARN_UNUSED_RESULT {
+    sb_ << "\r\n";
+    if (!content.empty()) {
+      sb_ << content;
+    }
+    if (sb_.is_error()) {
+      return Status::Error("Too much headers");
+    }
+    return sb_.as_cslice();
+  }
+
+ private:
+  static CSlice get_status_line(int http_status_code) {
+    if (http_status_code == 200) {
+      return CSlice("OK");
+    }
+    switch (http_status_code) {
+      case 201:
+        return CSlice("Created");
+      case 202:
+        return CSlice("Accepted");
+      case 204:
+        return CSlice("No Content");
+      case 206:
+        return CSlice("Partial Content");
+      case 301:
+        return CSlice("Moved Permanently");
+      case 302:
+        return CSlice("Found");
+      case 303:
+        return CSlice("See Other");
+      case 304:
+        return CSlice("Not Modified");
+      case 307:
+        return CSlice("Temporary Redirect");
+      case 400:
+        return CSlice("Bad Request");
+      case 401:
+        return CSlice("Unauthorized");
+      case 403:
+        return CSlice("Forbidden");
+      case 404:
+        return CSlice("Not Found");
+      case 405:
+        return CSlice("Method Not Allowed");
+      case 406:
+        return CSlice("Not Acceptable");
+      case 408:
+        return CSlice("Request Timeout");
+      case 409:
+        return CSlice("Conflict");
+      case 411:
+        return CSlice("Length Required");
+      case 413:
+        return CSlice("Request Entity Too Large");
+      case 414:
+        return CSlice("Request-URI Too Long");
+      case 415:
+        return CSlice("Unsupported Media Type");
+      case 418:
+        return CSlice("I'm a teapot");
+      case 429:
+        return CSlice("Too Many Requests");
+      case 431:
+        return CSlice("Request Header Fields Too Large");
+      case 480:
+        return CSlice("Temporarily Unavailable");
+      case 501:
+        return CSlice("Not Implemented");
+      case 502:
+        return CSlice("Bad Gateway");
+      case 503:
+        return CSlice("Service Unavailable");
+      case 505:
+        return CSlice("HTTP Version Not Supported");
+      default:
+        LOG_IF(ERROR, http_status_code != 500) << "Unsupported status code " << http_status_code << " returned";
+        return CSlice("Internal Server Error");
+    }
+  }
+
+  char header_[MAX_HEADER];
+  StringBuilder sb_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpInboundConnection.cpp b/libs/tdlib/td/tdnet/td/net/HttpInboundConnection.cpp
new file mode 100644
index 0000000000..533cdd5407
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpInboundConnection.cpp
@@ -0,0 +1,28 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/net/HttpInboundConnection.h"
+
+#include "td/utils/logging.h"
+
+namespace td {
+// HttpInboundConnection implementation
+HttpInboundConnection::HttpInboundConnection(SocketFd fd, size_t max_post_size, size_t max_files, int32 idle_timeout,
+                                             ActorShared<Callback> callback)
+    : HttpConnectionBase(State::Read, std::move(fd), max_post_size, max_files, idle_timeout)
+    , callback_(std::move(callback)) {
+}
+
+void HttpInboundConnection::on_query(HttpQueryPtr query) {
+  CHECK(!callback_.empty());
+  send_closure(callback_, &Callback::handle, std::move(query), ActorOwn<HttpInboundConnection>(actor_id(this)));
+}
+
+void HttpInboundConnection::on_error(Status error) {
+  // nothing to do
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpInboundConnection.h b/libs/tdlib/td/tdnet/td/net/HttpInboundConnection.h
new file mode 100644
index 0000000000..013b024592
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpInboundConnection.h
@@ -0,0 +1,43 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+
+#include "td/net/HttpConnectionBase.h"
+#include "td/net/HttpQuery.h"
+
+#include "td/utils/port/SocketFd.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+class HttpInboundConnection final : public detail::HttpConnectionBase {
+ public:
+  class Callback : public Actor {
+   public:
+    virtual void handle(HttpQueryPtr query, ActorOwn<HttpInboundConnection> connection) = 0;
+  };
+  // Inherited interface
+  // void write_next(BufferSlice buffer);
+  // void write_ok();
+  // void write_error(Status error);
+
+  HttpInboundConnection(SocketFd fd, size_t max_post_size, size_t max_files, int32 idle_timeout,
+                        ActorShared<Callback> callback);
+
+ private:
+  void on_query(HttpQueryPtr query) override;
+  void on_error(Status error) override;
+  void hangup() override {
+    callback_.release();
+    stop();
+  }
+  ActorShared<Callback> callback_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpOutboundConnection.cpp b/libs/tdlib/td/tdnet/td/net/HttpOutboundConnection.cpp
new file mode 100644
index 0000000000..f6efe7e07a
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpOutboundConnection.cpp
@@ -0,0 +1,23 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/net/HttpOutboundConnection.h"
+
+#include "td/utils/logging.h"
+
+namespace td {
+// HttpOutboundConnection implementation
+void HttpOutboundConnection::on_query(HttpQueryPtr query) {
+  CHECK(!callback_.empty());
+  send_closure(callback_, &Callback::handle, std::move(query));
+}
+
+void HttpOutboundConnection::on_error(Status error) {
+  CHECK(!callback_.empty());
+  send_closure(callback_, &Callback::on_connection_error, std::move(error));
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpOutboundConnection.h b/libs/tdlib/td/tdnet/td/net/HttpOutboundConnection.h
new file mode 100644
index 0000000000..d7496c59c4
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpOutboundConnection.h
@@ -0,0 +1,46 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+
+#include "td/net/HttpConnectionBase.h"
+#include "td/net/HttpQuery.h"
+
+#include "td/utils/Status.h"
+
+namespace td {
+
+class HttpOutboundConnection final : public detail::HttpConnectionBase {
+ public:
+  class Callback : public Actor {
+   public:
+    virtual void handle(HttpQueryPtr query) = 0;
+    virtual void on_connection_error(Status error) = 0;  // TODO rename to on_error
+  };
+  template <class FdT>
+  HttpOutboundConnection(FdT fd, size_t max_post_size, size_t max_files, int32 idle_timeout,
+                         ActorShared<Callback> callback)
+      : HttpConnectionBase(HttpConnectionBase::State::Write, std::move(fd), max_post_size, max_files, idle_timeout)
+      , callback_(std::move(callback)) {
+  }
+  // Inherited interface
+  // void write_next(BufferSlice buffer);
+  // void write_ok();
+  // void write_error(Status error);
+
+ private:
+  void on_query(HttpQueryPtr query) override;
+  void on_error(Status error) override;
+  void hangup() override {
+    callback_.release();
+    HttpConnectionBase::hangup();
+  }
+  ActorShared<Callback> callback_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpQuery.cpp b/libs/tdlib/td/tdnet/td/net/HttpQuery.cpp
new file mode 100644
index 0000000000..b4af0eef3f
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpQuery.cpp
@@ -0,0 +1,70 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/net/HttpQuery.h"
+
+#include <algorithm>
+
+namespace td {
+
+Slice HttpQuery::header(Slice key) const {
+  auto it = std::find_if(headers_.begin(), headers_.end(),
+                         [&key](const std::pair<MutableSlice, MutableSlice> &s) { return s.first == key; });
+  return it == headers_.end() ? Slice() : it->second;
+}
+
+MutableSlice HttpQuery::arg(Slice key) const {
+  auto it = std::find_if(args_.begin(), args_.end(),
+                         [&key](const std::pair<MutableSlice, MutableSlice> &s) { return s.first == key; });
+  return it == args_.end() ? MutableSlice() : it->second;
+}
+
+std::vector<std::pair<string, string>> HttpQuery::string_args() const {
+  std::vector<std::pair<string, string>> res;
+  for (auto &it : args_) {
+    res.push_back(std::make_pair(it.first.str(), it.second.str()));
+  }
+  return res;
+}
+
+StringBuilder &operator<<(StringBuilder &sb, const HttpQuery &q) {
+  switch (q.type_) {
+    case HttpQuery::Type::EMPTY:
+      sb << "EMPTY";
+      return sb;
+    case HttpQuery::Type::GET:
+      sb << "GET";
+      break;
+    case HttpQuery::Type::POST:
+      sb << "POST";
+      break;
+    case HttpQuery::Type::RESPONSE:
+      sb << "RESPONSE";
+      break;
+  }
+  if (q.type_ == HttpQuery::Type::RESPONSE) {
+    sb << ":" << q.code_ << ":" << q.reason_;
+  } else {
+    sb << ":" << q.url_path_;
+    for (auto &key_value : q.args_) {
+      sb << ":[" << key_value.first << ":" << key_value.second << "]";
+    }
+  }
+  if (q.keep_alive_) {
+    sb << ":keep-alive";
+  }
+  sb << "\n";
+  for (auto &key_value : q.headers_) {
+    sb << key_value.first << "=" << key_value.second << "\n";
+  }
+  sb << "BEGIN CONTENT\n";
+  sb << q.content_;
+  sb << "END CONTENT\n";
+
+  return sb;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpQuery.h b/libs/tdlib/td/tdnet/td/net/HttpQuery.h
new file mode 100644
index 0000000000..acab74ac66
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpQuery.h
@@ -0,0 +1,47 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/net/HttpFile.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+#include "td/utils/StringBuilder.h"
+
+#include <utility>
+
+namespace td {
+
+class HttpQuery {
+ public:
+  enum class Type : int8 { EMPTY, GET, POST, RESPONSE };
+
+  std::vector<BufferSlice> container_;
+  Type type_;
+  MutableSlice url_path_;
+  std::vector<std::pair<MutableSlice, MutableSlice>> args_;
+  int code_;
+  MutableSlice reason_;
+
+  bool keep_alive_;
+  std::vector<std::pair<MutableSlice, MutableSlice>> headers_;
+  std::vector<HttpFile> files_;
+  MutableSlice content_;
+
+  Slice header(Slice key) const;
+
+  MutableSlice arg(Slice key) const;
+
+  std::vector<std::pair<string, string>> string_args() const;
+};
+
+using HttpQueryPtr = std::unique_ptr<HttpQuery>;
+
+StringBuilder &operator<<(StringBuilder &sb, const HttpQuery &q);
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpReader.cpp b/libs/tdlib/td/tdnet/td/net/HttpReader.cpp
new file mode 100644
index 0000000000..1cfa7666a7
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpReader.cpp
@@ -0,0 +1,814 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/net/HttpReader.h"
+
+#include "td/utils/filesystem.h"
+#include "td/utils/find_boundary.h"
+#include "td/utils/format.h"
+#include "td/utils/Gzip.h"
+#include "td/utils/HttpUrl.h"
+#include "td/utils/JsonBuilder.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Parser.h"
+#include "td/utils/PathView.h"
+#include "td/utils/port/path.h"
+
+#include <cstring>
+
+namespace td {
+
+constexpr const char HttpReader::TEMP_DIRECTORY_PREFIX[];
+
+static size_t urldecode(Slice from, MutableSlice to, bool decode_plus_sign_as_space) {
+  size_t to_i = 0;
+  CHECK(to.size() >= from.size());
+  for (size_t from_i = 0, n = from.size(); from_i < n; from_i++) {
+    if (from[from_i] == '%' && from_i + 2 < n) {
+      int high = hex_to_int(from[from_i + 1]);
+      int low = hex_to_int(from[from_i + 2]);
+      if (high < 16 && low < 16) {
+        to[to_i++] = static_cast<char>(high * 16 + low);
+        from_i += 2;
+        continue;
+      }
+    }
+    to[to_i++] = decode_plus_sign_as_space && from[from_i] == '+' ? ' ' : from[from_i];
+  }
+  return to_i;
+}
+
+static MutableSlice urldecode_inplace(MutableSlice str, bool decode_plus_sign_as_space) {
+  size_t result_size = urldecode(str, str, decode_plus_sign_as_space);
+  str.truncate(result_size);
+  return str;
+}
+
+void HttpReader::init(ChainBufferReader *input, size_t max_post_size, size_t max_files) {
+  input_ = input;
+  state_ = ReadHeaders;
+  headers_read_length_ = 0;
+  content_length_ = 0;
+  query_ = nullptr;
+  max_post_size_ = max_post_size;
+  max_files_ = max_files;
+  total_parameters_length_ = 0;
+  total_headers_length_ = 0;
+}
+
+Result<size_t> HttpReader::read_next(HttpQuery *query) {
+  if (query_ != query) {
+    CHECK(query_ == nullptr);
+    query_ = query;
+  }
+  size_t need_size = input_->size() + 1;
+  while (true) {
+    if (state_ != ReadHeaders) {
+      flow_source_.wakeup();
+      if (flow_sink_.is_ready() && flow_sink_.status().is_error()) {
+        return Status::Error(400, "Bad Request: " + flow_sink_.status().message().str());
+      }
+      need_size = flow_source_.get_need_size();
+      if (need_size == 0) {
+        need_size = input_->size() + 1;
+      }
+    }
+    switch (state_) {
+      case ReadHeaders: {
+        auto result = split_header();
+        if (result.is_error() || result.ok() != 0) {
+          return result;
+        }
+        if (transfer_encoding_.empty() && content_length_ == 0) {
+          break;
+        }
+
+        flow_source_ = ByteFlowSource(input_);
+        ByteFlowInterface *source = &flow_source_;
+        if (transfer_encoding_.empty()) {
+          content_length_flow_ = HttpContentLengthByteFlow(content_length_);
+          *source >> content_length_flow_;
+          source = &content_length_flow_;
+        } else if (transfer_encoding_ == "chunked") {
+          chunked_flow_ = HttpChunkedByteFlow();
+          *source >> chunked_flow_;
+          source = &chunked_flow_;
+        } else {
+          LOG(ERROR) << "Unsupported " << tag("transfer-encoding", transfer_encoding_);
+          return Status::Error(501, "Unimplemented: unsupported transfer-encoding");
+        }
+
+        if (content_encoding_.empty()) {
+        } else if (content_encoding_ == "gzip" || content_encoding_ == "deflate") {
+          gzip_flow_ = GzipByteFlow(Gzip::Decode);
+          gzip_flow_.set_max_output_size(MAX_FILE_SIZE);
+          *source >> gzip_flow_;
+          source = &gzip_flow_;
+        } else {
+          LOG(ERROR) << "Unsupported " << tag("content-encoding", content_encoding_);
+          return Status::Error(415, "Unsupported Media Type: unsupported content-encoding");
+        }
+
+        flow_sink_ = ByteFlowSink();
+        *source >> flow_sink_;
+        content_ = flow_sink_.get_output();
+
+        if (content_length_ > MAX_CONTENT_SIZE) {
+          return Status::Error(413, PSLICE() << "Request Entity Too Large: content length is " << content_length_);
+        }
+
+        if (std::strstr(content_type_lowercased_.c_str(), "multipart/form-data")) {
+          state_ = ReadMultipartFormData;
+
+          const char *p = std::strstr(content_type_lowercased_.c_str(), "boundary");
+          if (p == nullptr) {
+            return Status::Error(400, "Bad Request: boundary not found");
+          }
+          p += 8;
+          ptrdiff_t offset = p - content_type_lowercased_.c_str();
+          p = static_cast<const char *>(
+              std::memchr(content_type_.begin() + offset, '=', content_type_.size() - offset));
+          if (p == nullptr) {
+            return Status::Error(400, "Bad Request: boundary value not found");
+          }
+          p++;
+          const char *end_p = static_cast<const char *>(std::memchr(p, ';', content_type_.end() - p));
+          if (end_p == nullptr) {
+            end_p = content_type_.end();
+          }
+          if (*p == '"' && p + 1 < end_p && end_p[-1] == '"') {
+            p++;
+            end_p--;
+          }
+
+          Slice boundary(p, static_cast<size_t>(end_p - p));
+          if (boundary.empty() || boundary.size() > MAX_BOUNDARY_LENGTH) {
+            return Status::Error(400, "Bad Request: boundary too big or empty");
+          }
+
+          boundary_ = "\r\n--" + boundary.str();
+          form_data_parse_state_ = SkipPrologue;
+          form_data_read_length_ = 0;
+          form_data_skipped_length_ = 0;
+        } else if (std::strstr(content_type_lowercased_.c_str(), "application/x-www-form-urlencoded") ||
+                   std::strstr(content_type_lowercased_.c_str(), "application/json")) {
+          state_ = ReadArgs;
+        } else {
+          form_data_skipped_length_ = 0;
+          state_ = ReadContent;
+        }
+        continue;
+      }
+      case ReadContent: {
+        if (content_->size() > max_post_size_) {
+          state_ = ReadContentToFile;
+          continue;
+        }
+        if (flow_sink_.is_ready()) {
+          CHECK(query_->container_.size() == 1u);
+          query_->container_.emplace_back(content_->cut_head(content_->size()).move_as_buffer_slice());
+          query_->content_ = query_->container_.back().as_slice();
+          break;
+        }
+
+        return need_size;
+      }
+      case ReadContentToFile: {
+        // save content to a file
+        if (temp_file_.empty()) {
+          auto file = open_temp_file("file");
+          if (file.is_error()) {
+            return Status::Error(500, "Internal Server Error: can't create temporary file");
+          }
+        }
+
+        auto size = content_->size();
+        if (size) {
+          TRY_STATUS(save_file_part(content_->cut_head(size).move_as_buffer_slice()));
+        }
+        if (flow_sink_.is_ready()) {
+          query_->files_.emplace_back("file", "", content_type_.str(), file_size_, temp_file_name_);
+          close_temp_file();
+          break;
+        }
+
+        return need_size;
+      }
+      case ReadArgs: {
+        auto size = content_->size();
+        if (size > MAX_TOTAL_PARAMETERS_LENGTH - total_parameters_length_) {
+          return Status::Error(413, "Request Entity Too Large: too much parameters");
+        }
+
+        if (flow_sink_.is_ready()) {
+          query_->container_.emplace_back(content_->cut_head(size).move_as_buffer_slice());
+          Status result;
+          if (std::strstr(content_type_lowercased_.c_str(), "application/x-www-form-urlencoded")) {
+            result = parse_parameters(query_->container_.back().as_slice());
+          } else {
+            result = parse_json_parameters(query_->container_.back().as_slice());
+          }
+          if (result.is_error()) {
+            if (result.code() == 413) {
+              return std::move(result);
+            }
+            LOG(INFO) << result.message();
+          }
+          query_->content_ = MutableSlice();
+          break;
+        }
+
+        return need_size;
+      }
+      case ReadMultipartFormData: {
+        TRY_RESULT(result, parse_multipart_form_data());
+        if (result) {
+          break;
+        }
+        return need_size;
+      }
+      default:
+        UNREACHABLE();
+    }
+    break;
+  }
+
+  init(input_, max_post_size_, max_files_);
+  return 0;
+}
+
+// returns Status on wrong request
+// returns true if parsing has finished
+// returns false if need more data
+Result<bool> HttpReader::parse_multipart_form_data() {
+  while (true) {
+    LOG(DEBUG) << "Parsing multipart form data in state " << form_data_parse_state_;
+    switch (form_data_parse_state_) {
+      case SkipPrologue:
+        if (find_boundary(content_->clone(), {boundary_.c_str() + 2, boundary_.size() - 2}, form_data_read_length_)) {
+          size_t to_skip = form_data_read_length_ + (boundary_.size() - 2);
+          content_->advance(to_skip);
+          form_data_skipped_length_ += to_skip;
+          form_data_read_length_ = 0;
+
+          form_data_parse_state_ = ReadPartHeaders;
+          continue;
+        }
+
+        content_->advance(form_data_read_length_);
+        form_data_skipped_length_ += form_data_read_length_;
+        form_data_read_length_ = 0;
+        return false;
+      case ReadPartHeaders:
+        if (find_boundary(content_->clone(), "\r\n\r\n", form_data_read_length_)) {
+          total_headers_length_ += form_data_read_length_;
+          if (total_headers_length_ > MAX_TOTAL_HEADERS_LENGTH) {
+            return Status::Error(431, "Request Header Fields Too Large: total headers size exceeded");
+          }
+          if (form_data_read_length_ == 0) {
+            // there is no headers at all
+            return Status::Error(400, "Bad Request: headers in multipart/form-data are empty");
+          }
+
+          content_->advance(2);  // "\r\n" after boundary
+          auto headers = content_->cut_head(form_data_read_length_).move_as_buffer_slice();
+          CHECK(headers.as_slice().size() == form_data_read_length_);
+          LOG(DEBUG) << "Parse headers in multipart form data: \"" << headers.as_slice() << "\"";
+          content_->advance(2);
+
+          form_data_skipped_length_ += form_data_read_length_ + 4;
+          form_data_read_length_ = 0;
+
+          field_name_ = MutableSlice();
+          file_field_name_.clear();
+          field_content_type_ = "application/octet-stream";
+          file_name_.clear();
+          CHECK(temp_file_.empty());
+          temp_file_name_.clear();
+
+          Parser headers_parser(headers.as_slice());
+          while (headers_parser.status().is_ok() && !headers_parser.data().empty()) {
+            MutableSlice header_name = headers_parser.read_till(':');
+            headers_parser.skip(':');
+            char *header_value_begin = headers_parser.ptr();
+            char *header_value_end;
+            do {
+              headers_parser.read_till('\r');
+              header_value_end = headers_parser.ptr();
+              headers_parser.skip('\r');
+              headers_parser.skip('\n');
+            } while (headers_parser.status().is_ok() &&
+                     (headers_parser.peek_char() == ' ' || headers_parser.peek_char() == '\t'));
+
+            MutableSlice header_value(header_value_begin, header_value_end);
+
+            header_name = trim(header_name);
+            header_value = trim(header_value);
+            to_lower_inplace(header_name);
+
+            if (header_name == "content-disposition") {
+              if (header_value.substr(0, 10) != "form-data;") {
+                return Status::Error(400, "Bad Request: expected form-data content disposition");
+              }
+              header_value.remove_prefix(10);
+              while (true) {
+                header_value = trim(header_value);
+                const char *key_end =
+                    static_cast<const char *>(std::memchr(header_value.data(), '=', header_value.size()));
+                if (key_end == nullptr) {
+                  break;
+                }
+                size_t key_size = key_end - header_value.data();
+                auto key = header_value.substr(0, key_size);
+                key = trim(key);
+
+                header_value.remove_prefix(key_size + 1);
+                const char *value_end =
+                    static_cast<const char *>(std::memchr(header_value.data(), ';', header_value.size()));
+                size_t value_size;
+                if (value_end == nullptr) {
+                  value_size = header_value.size();
+                } else {
+                  value_size = value_end - header_value.data();
+                }
+                auto value = header_value.substr(0, value_size);
+                value = trim(value);
+                if (value.size() > 1u && value[0] == '"' && value.back() == '"') {
+                  value = {value.data() + 1, value.size() - 2};
+                }
+                header_value.remove_prefix(value_size + (header_value.size() > value_size));
+
+                if (key == "name") {
+                  field_name_ = value;
+                } else if (key == "filename") {
+                  file_name_ = value.str();
+                } else {
+                  // ignore unknown parts of header
+                }
+              }
+            } else if (header_name == "content-type") {
+              field_content_type_ = header_value.str();
+            } else {
+              // ignore unknown header
+            }
+          }
+
+          if (headers_parser.status().is_error()) {
+            return Status::Error(400, "Bad Request: can't parse form data headers");
+          }
+
+          if (field_name_.empty()) {
+            return Status::Error(400, "Bad Request: field name in multipart/form-data not found");
+          }
+
+          if (!file_name_.empty()) {
+            // file
+            if (query_->files_.size() == max_files_) {
+              return Status::Error(413, "Request Entity Too Large: too much files attached");
+            }
+            auto file = open_temp_file(file_name_);
+            if (file.is_error()) {
+              return Status::Error(500, "Internal Server Error: can't create temporary file");
+            }
+
+            // don't need to save headers for files
+            file_field_name_ = field_name_.str();
+            form_data_parse_state_ = ReadFile;
+          } else {
+            // save headers for query parameters. They contain header names
+            query_->container_.push_back(std::move(headers));
+            form_data_parse_state_ = ReadPartValue;
+          }
+
+          continue;
+        }
+
+        if (total_headers_length_ + form_data_read_length_ > MAX_TOTAL_HEADERS_LENGTH) {
+          return Status::Error(431, "Request Header Fields Too Large: total headers size exceeded");
+        }
+        return false;
+      case ReadPartValue:
+        if (find_boundary(content_->clone(), boundary_, form_data_read_length_)) {
+          if (total_parameters_length_ + form_data_read_length_ > MAX_TOTAL_PARAMETERS_LENGTH) {
+            return Status::Error(413, "Request Entity Too Large: too much parameters in form data");
+          }
+
+          query_->container_.emplace_back(content_->cut_head(form_data_read_length_).move_as_buffer_slice());
+          MutableSlice value = query_->container_.back().as_slice();
+          content_->advance(boundary_.size());
+          form_data_skipped_length_ += form_data_read_length_ + boundary_.size();
+          form_data_read_length_ = 0;
+
+          if (begins_with(field_content_type_, "application/x-www-form-urlencoded")) {
+            // treat value as ordinary parameters
+            auto result = parse_parameters(value);
+            if (result.is_error()) {
+              return std::move(result);
+            }
+          } else {
+            total_parameters_length_ += form_data_read_length_;
+            LOG(DEBUG) << "Get ordinary parameter in multipart form data: \"" << field_name_ << "\": \"" << value
+                       << "\"";
+            query_->args_.emplace_back(field_name_, value);
+          }
+
+          form_data_parse_state_ = CheckForLastBoundary;
+          continue;
+        }
+        CHECK(content_->size() < form_data_read_length_ + boundary_.size());
+
+        if (total_parameters_length_ + form_data_read_length_ > MAX_TOTAL_PARAMETERS_LENGTH) {
+          return Status::Error(413, "Request Entity Too Large: too much parameters in form data");
+        }
+        return false;
+      case ReadFile: {
+        if (find_boundary(content_->clone(), boundary_, form_data_read_length_)) {
+          auto file_part = content_->cut_head(form_data_read_length_).move_as_buffer_slice();
+          content_->advance(boundary_.size());
+          form_data_skipped_length_ += form_data_read_length_ + boundary_.size();
+          form_data_read_length_ = 0;
+
+          TRY_STATUS(save_file_part(std::move(file_part)));
+
+          query_->files_.emplace_back(file_field_name_, file_name_, field_content_type_, file_size_, temp_file_name_);
+          close_temp_file();
+
+          form_data_parse_state_ = CheckForLastBoundary;
+          continue;
+        }
+
+        // TODO optimize?
+        auto file_part = content_->cut_head(form_data_read_length_).move_as_buffer_slice();
+        form_data_skipped_length_ += form_data_read_length_;
+        form_data_read_length_ = 0;
+        CHECK(content_->size() < boundary_.size());
+
+        TRY_STATUS(save_file_part(std::move(file_part)));
+        return false;
+      }
+      case CheckForLastBoundary: {
+        if (content_->size() < 2) {
+          // need more data
+          return false;
+        }
+
+        auto range = content_->clone();
+        char x[2];
+        range.advance(2, {x, 2});
+        if (x[0] == '-' && x[1] == '-') {
+          content_->advance(2);
+          form_data_skipped_length_ += 2;
+          form_data_parse_state_ = SkipEpilogue;
+        } else {
+          form_data_parse_state_ = ReadPartHeaders;
+        }
+        continue;
+      }
+      case SkipEpilogue: {
+        size_t size = content_->size();
+        LOG(DEBUG) << "Skipping epilogue. Have " << size << " bytes";
+        content_->advance(size);
+        form_data_skipped_length_ += size;
+        // TODO(now): check if form_data_skipped_length is too big
+        return flow_sink_.is_ready();
+      }
+      default:
+        UNREACHABLE();
+    }
+    break;
+  }
+
+  return true;
+}
+
+Result<size_t> HttpReader::split_header() {
+  if (find_boundary(input_->clone(), "\r\n\r\n", headers_read_length_)) {
+    query_->container_.clear();
+    auto a = input_->cut_head(headers_read_length_ + 2);
+    auto b = a.move_as_buffer_slice();
+    query_->container_.emplace_back(std::move(b));
+    // query_->container_.emplace_back(input_->cut_head(headers_read_length_ + 2).move_as_buffer_slice());
+    CHECK(query_->container_.back().size() == headers_read_length_ + 2);
+    input_->advance(2);
+    total_headers_length_ = headers_read_length_;
+    auto status = parse_head(query_->container_.back().as_slice());
+    if (status.is_error()) {
+      return std::move(status);
+    }
+    return 0;
+  }
+
+  if (input_->size() > MAX_TOTAL_HEADERS_LENGTH) {
+    return Status::Error(431, "Request Header Fields Too Large: total headers size exceeded");
+  }
+  return input_->size() + 1;
+}
+
+void HttpReader::process_header(MutableSlice header_name, MutableSlice header_value) {
+  header_name = trim(header_name);
+  header_value = trim(header_value);  // TODO need to remove "\r\n" from value
+  to_lower_inplace(header_name);
+  LOG(DEBUG) << "process_header [" << header_name << "=>" << header_value << "]";
+  query_->headers_.emplace_back(header_name, header_value);
+  // TODO: check if protocol is HTTP/1.1
+  query_->keep_alive_ = true;
+  if (header_name == "content-length") {
+    content_length_ = to_integer<size_t>(header_value);
+  } else if (header_name == "connection") {
+    to_lower_inplace(header_value);
+    if (header_value == "close") {
+      query_->keep_alive_ = false;
+    }
+  } else if (header_name == "content-type") {
+    content_type_ = header_value;
+    content_type_lowercased_ = header_value.str();
+    to_lower_inplace(content_type_lowercased_);
+  } else if (header_name == "content-encoding") {
+    to_lower_inplace(header_value);
+    content_encoding_ = header_value;
+  } else if (header_name == "transfer-encoding") {
+    to_lower_inplace(header_value);
+    transfer_encoding_ = header_value;
+  }
+}
+
+Status HttpReader::parse_url(MutableSlice url) {
+  size_t url_path_size = 0;
+  while (url_path_size < url.size() && url[url_path_size] != '?' && url[url_path_size] != '#') {
+    url_path_size++;
+  }
+
+  query_->url_path_ = urldecode_inplace({url.data(), url_path_size}, false);
+
+  if (url_path_size == url.size() || url[url_path_size] != '?') {
+    return Status::OK();
+  }
+  return parse_parameters(url.substr(url_path_size + 1));
+}
+
+Status HttpReader::parse_parameters(MutableSlice parameters) {
+  total_parameters_length_ += parameters.size();
+  if (total_parameters_length_ > MAX_TOTAL_PARAMETERS_LENGTH) {
+    return Status::Error(413, "Request Entity Too Large: too much parameters");
+  }
+  LOG(DEBUG) << "Parse parameters: \"" << parameters << "\"";
+
+  Parser parser(parameters);
+  while (!parser.data().empty()) {
+    auto key_value = parser.read_till_nofail('&');
+    parser.skip_nofail('&');
+    Parser kv_parser(key_value);
+    auto key = urldecode_inplace(kv_parser.read_till_nofail('='), true);
+    kv_parser.skip_nofail('=');
+    auto value = urldecode_inplace(kv_parser.data(), true);
+    query_->args_.emplace_back(key, value);
+  }
+
+  CHECK(parser.status().is_ok());
+  return Status::OK();
+}
+
+Status HttpReader::parse_json_parameters(MutableSlice parameters) {
+  if (parameters.empty()) {
+    return Status::OK();
+  }
+
+  total_parameters_length_ += parameters.size();
+  if (total_parameters_length_ > MAX_TOTAL_PARAMETERS_LENGTH) {
+    return Status::Error(413, "Request Entity Too Large: too much parameters");
+  }
+  LOG(DEBUG) << "Parse json parameters: \"" << parameters << "\"";
+
+  Parser parser(parameters);
+  parser.skip_whitespaces();
+  parser.skip('{');
+  if (parser.status().is_error()) {
+    return Status::Error(400, "Bad Request: json object expected");
+  }
+  while (true) {
+    parser.skip_whitespaces();
+    if (parser.try_skip('}')) {
+      parser.skip_whitespaces();
+      if (parser.empty()) {
+        return Status::OK();
+      }
+      return Status::Error(400, "Bad Request: unexpected data after object end");
+    }
+    if (parser.empty()) {
+      return Status::Error(400, "Bad Request: expected parameter name");
+    }
+    auto r_key = json_string_decode(parser);
+    if (r_key.is_error()) {
+      return Status::Error(400, string("Bad Request: can't parse parameter name: ") + r_key.error().message().c_str());
+    }
+    parser.skip_whitespaces();
+    if (!parser.try_skip(':')) {
+      return Status::Error(400, "Bad Request: can't parse object, ':' expected");
+    }
+    parser.skip_whitespaces();
+    Result<MutableSlice> r_value;
+    if (parser.peek_char() == '"') {
+      r_value = json_string_decode(parser);
+    } else {
+      const int32 DEFAULT_MAX_DEPTH = 100;
+      auto begin = parser.ptr();
+      auto result = do_json_skip(parser, DEFAULT_MAX_DEPTH);
+      if (result.is_ok()) {
+        r_value = MutableSlice(begin, parser.ptr());
+      } else {
+        r_value = result.move_as_error();
+      }
+    }
+    if (r_value.is_error()) {
+      return Status::Error(400,
+                           string("Bad Request: can't parse parameter value: ") + r_value.error().message().c_str());
+    }
+    query_->args_.emplace_back(r_key.move_as_ok(), r_value.move_as_ok());
+
+    parser.skip_whitespaces();
+    if (parser.peek_char() != '}' && !parser.try_skip(',')) {
+      return Status::Error(400, "Bad Request: expected next field or object end");
+    }
+  }
+  UNREACHABLE();
+  return Status::OK();
+}
+
+Status HttpReader::parse_head(MutableSlice head) {
+  Parser parser(head);
+
+  Slice type = parser.read_till(' ');
+  parser.skip(' ');
+  // GET POST HTTP/1.1
+  if (type == "GET") {
+    query_->type_ = HttpQuery::Type::GET;
+  } else if (type == "POST") {
+    query_->type_ = HttpQuery::Type::POST;
+  } else if (type.size() >= 4 && type.substr(0, 4) == "HTTP") {
+    if (type == "HTTP/1.1" || type == "HTTP/1.0") {
+      query_->type_ = HttpQuery::Type::RESPONSE;
+    } else {
+      LOG(INFO) << "Unsupported HTTP version: " << type;
+      return Status::Error(505, "HTTP Version Not Supported");
+    }
+  } else {
+    LOG(INFO) << "Not Implemented " << tag("type", type) << tag("head", head);
+    return Status::Error(501, "Not Implemented");
+  }
+
+  query_->args_.clear();
+
+  if (query_->type_ == HttpQuery::Type::RESPONSE) {
+    query_->code_ = to_integer<int32>(parser.read_till(' '));
+    parser.skip(' ');
+    query_->reason_ = parser.read_till('\r');
+  } else {
+    auto url_version = parser.read_till('\r');
+    auto space_pos = url_version.rfind(' ');
+    if (space_pos == static_cast<size_t>(-1)) {
+      return Status::Error(400, "Bad Request: wrong request line");
+    }
+
+    TRY_STATUS(parse_url(url_version.substr(0, space_pos)));
+
+    auto http_version = url_version.substr(space_pos + 1);
+    if (http_version != "HTTP/1.1" && http_version != "HTTP/1.0") {
+      LOG(WARNING) << "Unsupported HTTP version: " << http_version;
+      return Status::Error(505, "HTTP Version Not Supported");
+    }
+  }
+  parser.skip('\r');
+  parser.skip('\n');
+
+  content_length_ = 0;
+  content_type_ = "application/octet-stream";
+  content_type_lowercased_ = content_type_.str();
+  transfer_encoding_ = "";
+  content_encoding_ = "";
+
+  query_->keep_alive_ = false;
+  query_->headers_.clear();
+  query_->files_.clear();
+  query_->content_ = MutableSlice();
+  while (parser.status().is_ok() && !parser.data().empty()) {
+    MutableSlice header_name = parser.read_till(':');
+    parser.skip(':');
+    char *header_value_begin = parser.ptr();
+    char *header_value_end;
+    do {
+      parser.read_till('\r');
+      header_value_end = parser.ptr();
+      parser.skip('\r');
+      parser.skip('\n');
+    } while (parser.status().is_ok() && (parser.peek_char() == ' ' || parser.peek_char() == '\t'));
+
+    process_header(header_name, {header_value_begin, header_value_end});
+  }
+  return parser.status().is_ok() ? Status::OK() : Status::Error(400, "Bad Request");
+}
+
+Status HttpReader::open_temp_file(CSlice desired_file_name) {
+  CHECK(temp_file_.empty());
+
+  auto tmp_dir = get_temporary_dir();
+  if (tmp_dir.empty()) {
+    return Status::Error("Can't find temporary directory");
+  }
+
+  TRY_RESULT(dir, realpath(tmp_dir, true));
+  CHECK(!dir.empty());
+
+  auto first_try = try_open_temp_file(dir, desired_file_name);
+  if (first_try.is_ok()) {
+    return Status::OK();
+  }
+
+  // Creation of new file with desired name has failed. Trying to create unique directory for it
+  TRY_RESULT(directory, mkdtemp(dir, TEMP_DIRECTORY_PREFIX));
+  auto second_try = try_open_temp_file(directory, desired_file_name);
+  if (second_try.is_ok()) {
+    return Status::OK();
+  }
+  auto third_try = try_open_temp_file(directory, "file");
+  if (third_try.is_ok()) {
+    return Status::OK();
+  }
+
+  rmdir(directory).ignore();
+  LOG(WARNING) << "Failed to create temporary file " << desired_file_name << ": " << second_try.error();
+  return second_try.move_as_error();
+}
+
+Status HttpReader::try_open_temp_file(Slice directory_name, CSlice desired_file_name) {
+  CHECK(temp_file_.empty());
+  CHECK(!directory_name.empty());
+
+  string file_name = clean_filename(desired_file_name);
+  if (file_name.empty()) {
+    file_name = "file";
+  }
+
+  temp_file_name_.clear();
+  temp_file_name_.reserve(directory_name.size() + 1 + file_name.size());
+  temp_file_name_.append(directory_name.data(), directory_name.size());
+  if (temp_file_name_.back() != TD_DIR_SLASH) {
+    temp_file_name_ += TD_DIR_SLASH;
+  }
+  temp_file_name_.append(file_name.data(), file_name.size());
+
+  TRY_RESULT(opened_file, FileFd::open(temp_file_name_, FileFd::Write | FileFd::CreateNew, 0640));
+
+  file_size_ = 0;
+  temp_file_ = std::move(opened_file);
+  LOG(DEBUG) << "Created temporary file " << temp_file_name_;
+  return Status::OK();
+}
+
+Status HttpReader::save_file_part(BufferSlice &&file_part) {
+  file_size_ += narrow_cast<int64>(file_part.size());
+  if (file_size_ > MAX_FILE_SIZE) {
+    string file_name = temp_file_name_;
+    close_temp_file();
+    delete_temp_file(file_name);
+    return Status::Error(
+        413, PSLICE() << "Request Entity Too Large: file is too big to be uploaded " << tag("size", file_size_));
+  }
+
+  LOG(DEBUG) << "Save file part of size " << file_part.size() << " to file " << temp_file_name_;
+  auto result_written = temp_file_.write(file_part.as_slice());
+  if (result_written.is_error() || result_written.ok() != file_part.size()) {
+    string file_name = temp_file_name_;
+    close_temp_file();
+    delete_temp_file(file_name);
+    return Status::Error(500, "Internal server error: can't upload the file");
+  }
+  return Status::OK();
+}
+
+void HttpReader::close_temp_file() {
+  LOG(DEBUG) << "Close temporary file " << temp_file_name_;
+  CHECK(!temp_file_.empty());
+  temp_file_.close();
+  CHECK(temp_file_.empty());
+  temp_file_name_.clear();
+}
+
+void HttpReader::delete_temp_file(CSlice file_name) {
+  CHECK(!file_name.empty());
+  LOG(DEBUG) << "Unlink temporary file " << file_name;
+  unlink(file_name).ignore();
+  PathView path_view(file_name);
+  Slice parent = path_view.parent_dir();
+  const size_t prefix_length = std::strlen(TEMP_DIRECTORY_PREFIX);
+  if (parent.size() >= prefix_length + 7 &&
+      parent.substr(parent.size() - prefix_length - 7, prefix_length) == TEMP_DIRECTORY_PREFIX) {
+    LOG(DEBUG) << "Unlink temporary directory " << parent;
+    rmdir(Slice(parent.data(), parent.size() - 1).str()).ignore();
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/HttpReader.h b/libs/tdlib/td/tdnet/td/net/HttpReader.h
new file mode 100644
index 0000000000..74067d1291
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/HttpReader.h
@@ -0,0 +1,108 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/net/HttpChunkedByteFlow.h"
+#include "td/net/HttpContentLengthByteFlow.h"
+#include "td/net/HttpQuery.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/ByteFlow.h"
+#include "td/utils/common.h"
+#include "td/utils/GzipByteFlow.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+
+#include <limits>
+
+namespace td {
+
+class HttpReader {
+ public:
+  void init(ChainBufferReader *input, size_t max_post_size = std::numeric_limits<size_t>::max(),
+            size_t max_files = 100);
+  Result<size_t> read_next(HttpQuery *query) TD_WARN_UNUSED_RESULT;  // TODO move query to init
+
+  HttpReader() = default;
+  HttpReader(const HttpReader &other) = delete;
+  HttpReader &operator=(const HttpReader &other) = delete;
+  HttpReader(HttpReader &&other) = delete;
+  HttpReader &operator=(HttpReader &&other) = delete;
+  ~HttpReader() {
+    if (!temp_file_.empty()) {
+      temp_file_.close();
+    }
+  }
+
+  static void delete_temp_file(CSlice file_name);
+
+ private:
+  size_t max_post_size_;
+  size_t max_files_;
+
+  enum { ReadHeaders, ReadContent, ReadContentToFile, ReadArgs, ReadMultipartFormData } state_;
+  size_t headers_read_length_;
+  size_t content_length_;
+  ChainBufferReader *input_;
+  ByteFlowSource flow_source_;
+  HttpChunkedByteFlow chunked_flow_;
+  GzipByteFlow gzip_flow_;
+  HttpContentLengthByteFlow content_length_flow_;
+  ByteFlowSink flow_sink_;
+  ChainBufferReader *content_;
+
+  HttpQuery *query_;
+  Slice transfer_encoding_;
+  Slice content_encoding_;
+  Slice content_type_;
+  string content_type_lowercased_;
+  size_t total_parameters_length_;
+  size_t total_headers_length_;
+
+  string boundary_;
+  size_t form_data_read_length_;
+  size_t form_data_skipped_length_;
+  enum {
+    SkipPrologue,
+    ReadPartHeaders,
+    ReadPartValue,
+    ReadFile,
+    CheckForLastBoundary,
+    SkipEpilogue
+  } form_data_parse_state_;
+  MutableSlice field_name_;
+  string file_field_name_;
+  string field_content_type_;
+  string file_name_;
+  FileFd temp_file_;
+  string temp_file_name_;
+  int64 file_size_;
+
+  Result<size_t> split_header() TD_WARN_UNUSED_RESULT;
+  void process_header(MutableSlice header_name, MutableSlice header_value);
+  Result<bool> parse_multipart_form_data() TD_WARN_UNUSED_RESULT;
+  Status parse_url(MutableSlice url) TD_WARN_UNUSED_RESULT;
+  Status parse_parameters(MutableSlice parameters) TD_WARN_UNUSED_RESULT;
+  Status parse_json_parameters(MutableSlice parameters) TD_WARN_UNUSED_RESULT;
+  Status parse_head(MutableSlice head) TD_WARN_UNUSED_RESULT;
+
+  Status open_temp_file(CSlice desired_file_name) TD_WARN_UNUSED_RESULT;
+  Status try_open_temp_file(Slice directory_name, CSlice desired_file_name) TD_WARN_UNUSED_RESULT;
+  Status save_file_part(BufferSlice &&file_part) TD_WARN_UNUSED_RESULT;
+  void close_temp_file();
+
+  static constexpr size_t MAX_CONTENT_SIZE = 150 << 20;           // Some reasonable limit
+  static constexpr size_t MAX_TOTAL_PARAMETERS_LENGTH = 1 << 16;  // Some reasonable limit
+  static constexpr size_t MAX_TOTAL_HEADERS_LENGTH = 1 << 18;     // Some reasonable limit
+  static constexpr size_t MAX_BOUNDARY_LENGTH = 70;               // As defined by RFC1341
+  static constexpr int64 MAX_FILE_SIZE = 1500 << 20;              // Telegram server file size limit
+  static constexpr const char TEMP_DIRECTORY_PREFIX[] = "tdlib-server-tmp";
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/NetStats.h b/libs/tdlib/td/tdnet/td/net/NetStats.h
new file mode 100644
index 0000000000..e67f9fbc93
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/NetStats.h
@@ -0,0 +1,145 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/SchedulerLocalStorage.h"
+
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/Time.h"
+
+#include <atomic>
+#include <memory>
+
+namespace td {
+
+class NetStatsCallback {
+ public:
+  virtual void on_read(uint64 bytes) = 0;
+  virtual void on_write(uint64 bytes) = 0;
+  NetStatsCallback() = default;
+  NetStatsCallback(const NetStatsCallback &) = delete;
+  NetStatsCallback &operator=(const NetStatsCallback &) = delete;
+  virtual ~NetStatsCallback() = default;
+};
+
+struct NetStatsData {
+  uint64 read_size = 0;
+  uint64 write_size = 0;
+
+  uint64 count = 0;
+  double duration = 0;
+};
+
+inline NetStatsData operator+(const NetStatsData &a, const NetStatsData &b) {
+  NetStatsData res;
+  res.read_size = a.read_size + b.read_size;
+  res.write_size = a.write_size + b.write_size;
+  res.count = a.count + b.count;
+  res.duration = a.duration + b.duration;
+  return res;
+}
+inline NetStatsData operator-(const NetStatsData &a, const NetStatsData &b) {
+  NetStatsData res;
+  CHECK(a.read_size >= b.read_size);
+  res.read_size = a.read_size - b.read_size;
+
+  CHECK(a.write_size >= b.write_size);
+  res.write_size = a.write_size - b.write_size;
+
+  CHECK(a.count >= b.count);
+  res.count = a.count - b.count;
+
+  CHECK(a.duration >= b.duration);
+  res.duration = a.duration - b.duration;
+
+  return res;
+}
+
+inline StringBuilder &operator<<(StringBuilder &sb, const NetStatsData &data) {
+  return sb << tag("Rx size", format::as_size(data.read_size)) << tag("Tx size", format::as_size(data.write_size))
+            << tag("count", data.count) << tag("duration", format::as_time(data.duration));
+}
+
+class NetStats {
+ public:
+  class Callback {
+   public:
+    virtual void on_stats_updated() = 0;
+    Callback() = default;
+    Callback(const Callback &) = delete;
+    Callback &operator=(const Callback &) = delete;
+    virtual ~Callback() = default;
+  };
+
+  std::shared_ptr<NetStatsCallback> get_callback() const {
+    return impl_;
+  }
+
+  NetStatsData get_stats() const {
+    return impl_->get_stats();
+  }
+
+  // do it before get_callback
+  void set_callback(std::unique_ptr<Callback> callback) {
+    impl_->set_callback(std::move(callback));
+  }
+
+ private:
+  class Impl : public NetStatsCallback {
+   public:
+    NetStatsData get_stats() const {
+      NetStatsData res;
+      local_net_stats_.for_each([&](auto &stats) {
+        res.read_size += stats.read_size.load(std::memory_order_relaxed);
+        res.write_size += stats.write_size.load(std::memory_order_relaxed);
+      });
+      return res;
+    }
+    void set_callback(std::unique_ptr<Callback> callback) {
+      callback_ = std::move(callback);
+    }
+
+   private:
+    struct LocalNetStats {
+      double last_update = 0;
+      uint64 unsync_size = 0;
+      std::atomic<uint64> read_size{0};
+      std::atomic<uint64> write_size{0};
+    };
+    SchedulerLocalStorage<LocalNetStats> local_net_stats_;
+    std::unique_ptr<Callback> callback_;
+
+    void on_read(uint64 size) final {
+      auto &stats = local_net_stats_.get();
+      stats.read_size.fetch_add(size, std::memory_order_relaxed);
+
+      on_change(stats, size);
+    }
+    void on_write(uint64 size) final {
+      auto &stats = local_net_stats_.get();
+      stats.write_size.fetch_add(size, std::memory_order_relaxed);
+
+      on_change(stats, size);
+    }
+
+    void on_change(LocalNetStats &stats, uint64 size) {
+      stats.unsync_size += size;
+      auto now = Time::now_cached();
+      if (stats.unsync_size > 10000 || now - stats.last_update > 5 * 60) {
+        stats.unsync_size = 0;
+        stats.last_update = now;
+        callback_->on_stats_updated();
+      }
+    }
+  };
+  std::shared_ptr<Impl> impl_{std::make_shared<Impl>()};
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/Socks5.cpp b/libs/tdlib/td/tdnet/td/net/Socks5.cpp
new file mode 100644
index 0000000000..02e1e067ea
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/Socks5.cpp
@@ -0,0 +1,249 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/net/Socks5.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/Slice.h"
+
+namespace td {
+
+static int VERBOSITY_NAME(socks5) = VERBOSITY_NAME(DEBUG);
+
+Socks5::Socks5(SocketFd socket_fd, IPAddress ip_address, string username, string password,
+               std::unique_ptr<Callback> callback, ActorShared<> parent)
+    : fd_(std::move(socket_fd))
+    , ip_address_(std::move(ip_address))
+    , username_(std::move(username))
+    , password_(std::move(password))
+    , callback_(std::move(callback))
+    , parent_(std::move(parent)) {
+}
+
+void Socks5::on_error(Status status) {
+  CHECK(status.is_error());
+  VLOG(socks5) << "Receive " << status;
+  if (callback_) {
+    callback_->set_result(std::move(status));
+    callback_.reset();
+  }
+  stop();
+}
+
+void Socks5::tear_down() {
+  VLOG(socks5) << "Finish to connect to proxy";
+  unsubscribe(fd_.get_fd());
+  fd_.get_fd().set_observer(nullptr);
+  if (callback_) {
+    callback_->set_result(std::move(fd_));
+    callback_.reset();
+  }
+}
+
+void Socks5::hangup() {
+  on_error(Status::Error("Cancelled"));
+}
+
+void Socks5::start_up() {
+  VLOG(socks5) << "Begin to connect to proxy";
+  fd_.get_fd().set_observer(this);
+  subscribe(fd_.get_fd());
+  set_timeout_in(10);
+  if (can_write(fd_)) {
+    loop();
+  }
+}
+
+void Socks5::send_greeting() {
+  VLOG(socks5) << "Send greeting to proxy";
+  CHECK(state_ == State::SendGreeting);
+  state_ = State::WaitGreetingResponse;
+
+  string greeting;
+  greeting += '\x05';
+  bool use_username = !username_.empty();
+  char authentication_count = use_username ? '\x02' : '\x01';
+  greeting += authentication_count;
+  greeting += '\0';
+  if (use_username) {
+    greeting += '\x02';
+  }
+
+  fd_.output_buffer().append(greeting);
+}
+
+Status Socks5::wait_greeting_response() {
+  auto &buf = fd_.input_buffer();
+  VLOG(socks5) << "Receive greeting response of size " << buf.size();
+  if (buf.size() < 2) {
+    return Status::OK();
+  }
+  auto buffer_slice = buf.read_as_buffer_slice(2);
+  auto slice = buffer_slice.as_slice();
+  if (slice[0] != '\x05') {
+    return Status::Error(PSLICE() << "Unsupported socks protocol version " << int(slice[0]));
+  }
+  auto authentication_method = slice[1];
+  if (authentication_method == '\0') {
+    state_ = State::SendIpAddress;
+    send_ip_address();
+    return Status::OK();
+  }
+  if (authentication_method == '\x02') {
+    return send_username_password();
+  }
+  return Status::Error("Unsupported authentication mode");
+}
+
+Status Socks5::send_username_password() {
+  VLOG(socks5) << "Send username and password";
+  if (username_.size() >= 128) {
+    return Status::Error("Username is too long");
+  }
+  if (password_.size() >= 128) {
+    return Status::Error("Password is too long");
+  }
+
+  string request;
+  request += '\x01';
+  request += narrow_cast<char>(username_.size());
+  request += username_;
+  request += narrow_cast<char>(password_.size());
+  request += password_;
+  fd_.output_buffer().append(request);
+  state_ = State::WaitPasswordResponse;
+
+  return Status::OK();
+}
+
+Status Socks5::wait_password_response() {
+  auto &buf = fd_.input_buffer();
+  VLOG(socks5) << "Receive password response of size " << buf.size();
+  if (buf.size() < 2) {
+    return Status::OK();
+  }
+  auto buffer_slice = buf.read_as_buffer_slice(2);
+  auto slice = buffer_slice.as_slice();
+  if (slice[0] != '\x01') {
+    return Status::Error(PSLICE() << "Unsupported socks subnegotiation protocol version " << int(slice[0]));
+  }
+  if (slice[1] != '\x00') {
+    return Status::Error("Wrong username or password");
+  }
+
+  state_ = State::SendIpAddress;
+  send_ip_address();
+  return Status::OK();
+}
+
+void Socks5::send_ip_address() {
+  VLOG(socks5) << "Send IP address";
+  CHECK(state_ == State::SendIpAddress);
+  callback_->on_connected();
+  string request;
+  request += '\x05';
+  request += '\x01';
+  request += '\x00';
+  if (ip_address_.is_ipv4()) {
+    request += '\x01';
+    auto ipv4 = ip_address_.get_ipv4();
+    request += static_cast<char>(ipv4 & 255);
+    request += static_cast<char>((ipv4 >> 8) & 255);
+    request += static_cast<char>((ipv4 >> 16) & 255);
+    request += static_cast<char>((ipv4 >> 24) & 255);
+  } else {
+    request += '\x04';
+    request += ip_address_.get_ipv6().str();
+  }
+  auto port = ip_address_.get_port();
+  request += static_cast<char>((port >> 8) & 255);
+  request += static_cast<char>(port & 255);
+  fd_.output_buffer().append(request);
+  state_ = State::WaitIpAddressResponse;
+}
+
+Status Socks5::wait_ip_address_response() {
+  CHECK(state_ == State::WaitIpAddressResponse);
+  auto it = fd_.input_buffer().clone();
+  VLOG(socks5) << "Receive IP address response of size " << it.size();
+  if (it.size() < 4) {
+    return Status::OK();
+  }
+  char c;
+  MutableSlice c_slice(&c, 1);
+  it.advance(1, c_slice);
+  if (c != '\x05') {
+    return Status::Error("Invalid response");
+  }
+  it.advance(1, c_slice);
+  if (c != '\0') {
+    return Status::Error(PSLICE() << tag("code", c));
+  }
+  it.advance(1, c_slice);
+  if (c != '\0') {
+    return Status::Error("byte must be zero");
+  }
+  it.advance(1, c_slice);
+  if (c == '\x01') {
+    if (it.size() < 4) {
+      return Status::OK();
+    }
+    it.advance(4);
+  } else if (c == '\x04') {
+    if (it.size() < 16) {
+      return Status::OK();
+    }
+    it.advance(16);
+  } else {
+    return Status::Error("Invalid response");
+  }
+  if (it.size() < 2) {
+    return Status::OK();
+  }
+  it.advance(2);
+  stop();
+  return Status::OK();
+}
+
+void Socks5::loop() {
+  auto status = [&] {
+    TRY_STATUS(fd_.flush_read());
+    switch (state_) {
+      case State::SendGreeting:
+        send_greeting();
+        break;
+      case State::WaitGreetingResponse:
+        TRY_STATUS(wait_greeting_response());
+        break;
+      case State::WaitPasswordResponse:
+        TRY_STATUS(wait_password_response());
+        break;
+      case State::WaitIpAddressResponse:
+        TRY_STATUS(wait_ip_address_response());
+        break;
+      case State::SendIpAddress:
+      case State::Stop:
+        UNREACHABLE();
+    }
+    TRY_STATUS(fd_.flush_write());
+    return Status::OK();
+  }();
+  if (status.is_error()) {
+    on_error(std::move(status));
+  }
+  if (can_close(fd_)) {
+    on_error(Status::Error("Connection closed"));
+  }
+}
+
+void Socks5::timeout_expired() {
+  on_error(Status::Error("Timeout expired"));
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/Socks5.h b/libs/tdlib/td/tdnet/td/net/Socks5.h
new file mode 100644
index 0000000000..b67a33c282
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/Socks5.h
@@ -0,0 +1,71 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/utils/BufferedFd.h"
+#include "td/utils/common.h"
+#include "td/utils/port/IPAddress.h"
+#include "td/utils/port/SocketFd.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+class Socks5 : public Actor {
+ public:
+  class Callback {
+   public:
+    Callback() = default;
+    Callback(const Callback &) = delete;
+    Callback &operator=(const Callback &) = delete;
+    virtual ~Callback() = default;
+
+    virtual void set_result(Result<SocketFd>) = 0;
+    virtual void on_connected() = 0;
+  };
+
+  Socks5(SocketFd socket_fd, IPAddress ip_address, string username, string password, std::unique_ptr<Callback> callback,
+         ActorShared<> parent);
+
+ private:
+  BufferedFd<SocketFd> fd_;
+  IPAddress ip_address_;
+  string username_;
+  string password_;
+  std::unique_ptr<Callback> callback_;
+  ActorShared<> parent_;
+
+  void on_error(Status status);
+  void tear_down() override;
+  void start_up() override;
+  void hangup() override;
+
+  enum class State {
+    SendGreeting,
+    WaitGreetingResponse,
+    WaitPasswordResponse,
+    SendIpAddress,
+    WaitIpAddressResponse,
+    Stop
+  } state_ = State::SendGreeting;
+
+  void send_greeting();
+  Status wait_greeting_response();
+  Status send_username_password();
+
+  Status wait_password_response();
+
+  void send_ip_address();
+  Status wait_ip_address_response();
+
+  void loop() override;
+  void timeout_expired() override;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/SslFd.cpp b/libs/tdlib/td/tdnet/td/net/SslFd.cpp
new file mode 100644
index 0000000000..f6f7557235
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/SslFd.cpp
@@ -0,0 +1,280 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/net/SslFd.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/StackAllocator.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/Time.h"
+
+#include <openssl/err.h>
+#include <openssl/evp.h>
+#include <openssl/ssl.h>
+#include <openssl/x509v3.h>
+
+#include <map>
+#include <mutex>
+
+namespace td {
+
+#if !TD_WINDOWS
+static int verify_callback(int preverify_ok, X509_STORE_CTX *ctx) {
+  if (!preverify_ok) {
+    char buf[256];
+    X509_NAME_oneline(X509_get_subject_name(X509_STORE_CTX_get_current_cert(ctx)), buf, 256);
+
+    int err = X509_STORE_CTX_get_error(ctx);
+    auto warning = PSTRING() << "verify error:num=" << err << ":" << X509_verify_cert_error_string(err)
+                             << ":depth=" << X509_STORE_CTX_get_error_depth(ctx) << ":" << buf;
+    double now = Time::now();
+
+    static std::mutex warning_mutex;
+    {
+      std::lock_guard<std::mutex> lock(warning_mutex);
+      static std::map<std::string, double> next_warning_time;
+      double &next = next_warning_time[warning];
+      if (next <= now) {
+        next = now + 300;  // one warning per 5 minutes
+        LOG(WARNING) << warning;
+      }
+    }
+  }
+
+  return preverify_ok;
+}
+#endif
+
+namespace {
+
+Status create_openssl_error(int code, Slice message) {
+  const int buf_size = 1 << 12;
+  auto buf = StackAllocator::alloc(buf_size);
+  StringBuilder sb(buf.as_slice());
+
+  sb << message;
+  while (unsigned long error_code = ERR_get_error()) {
+    sb << "{" << error_code << ", " << ERR_error_string(error_code, nullptr) << "}";
+  }
+  LOG_IF(ERROR, sb.is_error()) << "OPENSSL error buffer overflow";
+  return Status::Error(code, sb.as_cslice());
+}
+
+void openssl_clear_errors(Slice from) {
+  if (ERR_peek_error() != 0) {
+    LOG(ERROR) << from << ": " << create_openssl_error(0, "Unprocessed OPENSSL_ERROR");
+  }
+  errno = 0;
+}
+
+void do_ssl_shutdown(SSL *ssl_handle) {
+  if (!SSL_is_init_finished(ssl_handle)) {
+    return;
+  }
+  openssl_clear_errors("Before SSL_shutdown");
+  SSL_set_quiet_shutdown(ssl_handle, 1);
+  SSL_shutdown(ssl_handle);
+  openssl_clear_errors("After SSL_shutdown");
+}
+
+}  // namespace
+
+SslFd::SslFd(SocketFd &&fd, SSL *ssl_handle_, SSL_CTX *ssl_ctx_)
+    : fd_(std::move(fd)), ssl_handle_(ssl_handle_), ssl_ctx_(ssl_ctx_) {
+}
+
+Result<SslFd> SslFd::init(SocketFd fd, CSlice host, CSlice cert_file, VerifyPeer verify_peer) {
+#if TD_WINDOWS
+  return Status::Error("TODO");
+#else
+  static bool init_openssl = [] {
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+    return OPENSSL_init_ssl(0, nullptr) != 0;
+#else
+    OpenSSL_add_all_algorithms();
+    SSL_load_error_strings();
+    return OpenSSL_add_ssl_algorithms() != 0;
+#endif
+  }();
+  CHECK(init_openssl);
+
+  openssl_clear_errors("Before SslFd::init");
+  CHECK(!fd.empty());
+
+  auto ssl_method =
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+      TLS_client_method();
+#else
+      SSLv23_client_method();
+#endif
+  if (ssl_method == nullptr) {
+    return create_openssl_error(-6, "Failed to create an SSL client method");
+  }
+
+  auto ssl_ctx = SSL_CTX_new(ssl_method);
+  if (ssl_ctx == nullptr) {
+    return create_openssl_error(-7, "Failed to create an SSL context");
+  }
+  auto ssl_ctx_guard = ScopeExit() + [&]() { SSL_CTX_free(ssl_ctx); };
+  long options = 0;
+#ifdef SSL_OP_NO_SSLv2
+  options |= SSL_OP_NO_SSLv2;
+#endif
+#ifdef SSL_OP_NO_SSLv3
+  options |= SSL_OP_NO_SSLv3;
+#endif
+  SSL_CTX_set_options(ssl_ctx, options);
+  SSL_CTX_set_mode(ssl_ctx, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER | SSL_MODE_ENABLE_PARTIAL_WRITE);
+
+  if (cert_file.empty()) {
+    SSL_CTX_set_default_verify_paths(ssl_ctx);
+  } else {
+    if (SSL_CTX_load_verify_locations(ssl_ctx, cert_file.c_str(), nullptr) == 0) {
+      return create_openssl_error(-8, "Failed to set custom cert file");
+    }
+  }
+  if (VERIFY_PEER && verify_peer == VerifyPeer::On) {
+    SSL_CTX_set_verify(ssl_ctx, SSL_VERIFY_PEER, verify_callback);
+
+    if (VERIFY_DEPTH != -1) {
+      SSL_CTX_set_verify_depth(ssl_ctx, VERIFY_DEPTH);
+    }
+  } else {
+    SSL_CTX_set_verify(ssl_ctx, SSL_VERIFY_NONE, nullptr);
+  }
+
+  // TODO(now): cipher list
+  string cipher_list;
+  if (SSL_CTX_set_cipher_list(ssl_ctx, cipher_list.empty() ? "DEFAULT" : cipher_list.c_str()) == 0) {
+    return create_openssl_error(-9, PSLICE() << "Failed to set cipher list \"" << cipher_list << '"');
+  }
+
+  auto ssl_handle = SSL_new(ssl_ctx);
+  if (ssl_handle == nullptr) {
+    return create_openssl_error(-13, "Failed to create an SSL handle");
+  }
+  auto ssl_handle_guard = ScopeExit() + [&]() {
+    do_ssl_shutdown(ssl_handle);
+    SSL_free(ssl_handle);
+  };
+
+#if OPENSSL_VERSION_NUMBER >= 0x10002000L
+  X509_VERIFY_PARAM *param = SSL_get0_param(ssl_handle);
+  /* Enable automatic hostname checks */
+  // TODO: X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
+  X509_VERIFY_PARAM_set_hostflags(param, 0);
+  X509_VERIFY_PARAM_set1_host(param, host.c_str(), 0);
+#else
+#warning DANGEROUS! HTTPS HOST WILL NOT BE CHECKED. INSTALL OPENSSL >= 1.0.2 OR IMPLEMENT HTTPS HOST CHECK MANUALLY
+#endif
+
+  if (!SSL_set_fd(ssl_handle, fd.get_fd().get_native_fd())) {
+    return create_openssl_error(-14, "Failed to set fd");
+  }
+
+#if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
+  auto host_str = host.str();
+  SSL_set_tlsext_host_name(ssl_handle, MutableCSlice(host_str).begin());
+#endif
+  SSL_set_connect_state(ssl_handle);
+
+  ssl_ctx_guard.dismiss();
+  ssl_handle_guard.dismiss();
+  return SslFd(std::move(fd), ssl_handle, ssl_ctx);
+#endif
+}
+
+Result<size_t> SslFd::process_ssl_error(int ret, int *mask) {
+#if TD_WINDOWS
+  return Status::Error("TODO");
+#else
+  auto openssl_errno = errno;
+  int error = SSL_get_error(ssl_handle_, ret);
+  LOG(INFO) << "SSL ERROR: " << ret << " " << error;
+  switch (error) {
+    case SSL_ERROR_NONE:
+      LOG(ERROR) << "SSL_get_error returned no error";
+      return 0;
+    case SSL_ERROR_ZERO_RETURN:
+      LOG(DEBUG) << "SSL_ERROR_ZERO_RETURN";
+      fd_.get_fd().update_flags(Fd::Close);
+      write_mask_ |= Fd::Error;
+      *mask |= Fd::Error;
+      return 0;
+    case SSL_ERROR_WANT_READ:
+      LOG(DEBUG) << "SSL_ERROR_WANT_READ";
+      fd_.get_fd().clear_flags(Fd::Read);
+      *mask |= Fd::Read;
+      return 0;
+    case SSL_ERROR_WANT_WRITE:
+      LOG(DEBUG) << "SSL_ERROR_WANT_WRITE";
+      fd_.get_fd().clear_flags(Fd::Write);
+      *mask |= Fd::Write;
+      return 0;
+    case SSL_ERROR_WANT_CONNECT:
+    case SSL_ERROR_WANT_ACCEPT:
+    case SSL_ERROR_WANT_X509_LOOKUP:
+      LOG(DEBUG) << "SSL_ERROR: CONNECT ACCEPT LOOKUP";
+      fd_.get_fd().clear_flags(Fd::Write);
+      *mask |= Fd::Write;
+      return 0;
+    case SSL_ERROR_SYSCALL:
+      LOG(DEBUG) << "SSL_ERROR_SYSCALL";
+      if (ERR_peek_error() == 0) {
+        if (openssl_errno != 0) {
+          CHECK(openssl_errno != EAGAIN);
+          return Status::PosixError(openssl_errno, "SSL_ERROR_SYSCALL");
+        } else {
+          // Socket was closed from the other side, probably. Not an error
+          fd_.get_fd().update_flags(Fd::Close);
+          write_mask_ |= Fd::Error;
+          *mask |= Fd::Error;
+          return 0;
+        }
+      }
+    /* fall through */
+    default:
+      LOG(DEBUG) << "SSL_ERROR Default";
+      fd_.get_fd().update_flags(Fd::Close);
+      write_mask_ |= Fd::Error;
+      read_mask_ |= Fd::Error;
+      return create_openssl_error(1, "SSL error ");
+  }
+#endif
+}
+
+Result<size_t> SslFd::write(Slice slice) {
+  openssl_clear_errors("Before SslFd::write");
+  auto size = SSL_write(ssl_handle_, slice.data(), static_cast<int>(slice.size()));
+  if (size <= 0) {
+    return process_ssl_error(size, &write_mask_);
+  }
+  return size;
+}
+Result<size_t> SslFd::read(MutableSlice slice) {
+  openssl_clear_errors("Before SslFd::read");
+  auto size = SSL_read(ssl_handle_, slice.data(), static_cast<int>(slice.size()));
+  if (size <= 0) {
+    return process_ssl_error(size, &read_mask_);
+  }
+  return size;
+}
+
+void SslFd::close() {
+  if (fd_.empty()) {
+    CHECK(!ssl_handle_ && !ssl_ctx_);
+    return;
+  }
+  CHECK(ssl_handle_ && ssl_ctx_);
+  do_ssl_shutdown(ssl_handle_);
+  SSL_free(ssl_handle_);
+  ssl_handle_ = nullptr;
+  SSL_CTX_free(ssl_ctx_);
+  ssl_ctx_ = nullptr;
+  fd_.close();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/SslFd.h b/libs/tdlib/td/tdnet/td/net/SslFd.h
new file mode 100644
index 0000000000..c197b9c318
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/SslFd.h
@@ -0,0 +1,109 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/SocketFd.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <openssl/ssl.h>  // TODO can we remove it from header and make target_link_libraries dependence PRIVATE?
+
+namespace td {
+
+class SslFd {
+ public:
+  enum class VerifyPeer { On, Off };
+  static Result<SslFd> init(SocketFd fd, CSlice host, CSlice cert_file = CSlice(),
+                            VerifyPeer verify_peer = VerifyPeer::On) TD_WARN_UNUSED_RESULT;
+
+  SslFd(const SslFd &other) = delete;
+  SslFd &operator=(const SslFd &other) = delete;
+  SslFd(SslFd &&other)
+      : fd_(std::move(other.fd_))
+      , write_mask_(other.write_mask_)
+      , read_mask_(other.read_mask_)
+      , ssl_handle_(other.ssl_handle_)
+      , ssl_ctx_(other.ssl_ctx_) {
+    other.ssl_handle_ = nullptr;
+    other.ssl_ctx_ = nullptr;
+  }
+  SslFd &operator=(SslFd &&other) {
+    close();
+
+    fd_ = std::move(other.fd_);
+    write_mask_ = other.write_mask_;
+    read_mask_ = other.read_mask_;
+    ssl_handle_ = other.ssl_handle_;
+    ssl_ctx_ = other.ssl_ctx_;
+
+    other.ssl_handle_ = nullptr;
+    other.ssl_ctx_ = nullptr;
+    return *this;
+  }
+
+  const Fd &get_fd() const {
+    return fd_.get_fd();
+  }
+
+  Fd &get_fd() {
+    return fd_.get_fd();
+  }
+
+  Status get_pending_error() TD_WARN_UNUSED_RESULT {
+    return fd_.get_pending_error();
+  }
+
+  Result<size_t> write(Slice slice) TD_WARN_UNUSED_RESULT;
+  Result<size_t> read(MutableSlice slice) TD_WARN_UNUSED_RESULT;
+
+  void close();
+
+  int32 get_flags() const {
+    int32 res = 0;
+    int32 fd_flags = fd_.get_flags();
+    fd_flags &= ~Fd::Error;
+    if (fd_flags & Fd::Close) {
+      res |= Fd::Close;
+    }
+    write_mask_ &= ~fd_flags;
+    read_mask_ &= ~fd_flags;
+    if (write_mask_ == 0) {
+      res |= Fd::Write;
+    }
+    if (read_mask_ == 0) {
+      res |= Fd::Read;
+    }
+    return res;
+  }
+
+  bool empty() const {
+    return fd_.empty();
+  }
+
+  ~SslFd() {
+    close();
+  }
+
+ private:
+  static constexpr bool VERIFY_PEER = true;
+  static constexpr int VERIFY_DEPTH = 10;
+
+  SocketFd fd_;
+  mutable int write_mask_ = 0;
+  mutable int read_mask_ = 0;
+
+  // TODO unique_ptr
+  SSL *ssl_handle_ = nullptr;
+  SSL_CTX *ssl_ctx_ = nullptr;
+
+  SslFd(SocketFd &&fd, SSL *ssl_handle_, SSL_CTX *ssl_ctx_);
+
+  Result<size_t> process_ssl_error(int ret, int *mask) TD_WARN_UNUSED_RESULT;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/TcpListener.cpp b/libs/tdlib/td/tdnet/td/net/TcpListener.cpp
new file mode 100644
index 0000000000..54531f9b60
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/TcpListener.cpp
@@ -0,0 +1,62 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/net/TcpListener.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/port/Fd.h"
+
+namespace td {
+// TcpListener implementation
+TcpListener::TcpListener(int port, ActorShared<Callback> callback) : port_(port), callback_(std::move(callback)) {
+}
+
+void TcpListener::hangup() {
+  stop();
+}
+
+void TcpListener::start_up() {
+  auto r_socket = ServerSocketFd::open(port_);
+  if (r_socket.is_error()) {
+    LOG(ERROR) << "Can't open server socket: " << r_socket.error();
+    set_timeout_in(5);
+    return;
+  }
+  server_fd_ = r_socket.move_as_ok();
+  server_fd_.get_fd().set_observer(this);
+  subscribe(server_fd_.get_fd());
+}
+
+void TcpListener::tear_down() {
+  LOG(ERROR) << "TcpListener closed";
+  if (!server_fd_.empty()) {
+    unsubscribe_before_close(server_fd_.get_fd());
+    server_fd_.close();
+  }
+}
+
+void TcpListener::loop() {
+  if (server_fd_.empty()) {
+    start_up();
+  }
+  while (can_read(server_fd_)) {
+    auto r_socket_fd = server_fd_.accept();
+    if (r_socket_fd.is_error()) {
+      if (r_socket_fd.error().code() != -1) {
+        LOG(ERROR) << r_socket_fd.error();
+      }
+      continue;
+    }
+    send_closure(callback_, &Callback::accept, r_socket_fd.move_as_ok());
+  }
+
+  if (can_close(server_fd_)) {
+    LOG(ERROR) << "HELLO!";
+    stop();
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/TcpListener.h b/libs/tdlib/td/tdnet/td/net/TcpListener.h
new file mode 100644
index 0000000000..f2e61a2387
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/TcpListener.h
@@ -0,0 +1,35 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/actor/actor.h"
+
+#include "td/utils/port/ServerSocketFd.h"
+#include "td/utils/port/SocketFd.h"
+
+namespace td {
+
+class TcpListener final : public Actor {
+ public:
+  class Callback : public Actor {
+   public:
+    virtual void accept(SocketFd fd) = 0;
+  };
+
+  TcpListener(int port, ActorShared<Callback> callback);
+  void hangup() override;
+
+ private:
+  int port_;
+  ServerSocketFd server_fd_;
+  ActorShared<Callback> callback_;
+  void start_up() override;
+  void tear_down() override;
+  void loop() override;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/Wget.cpp b/libs/tdlib/td/tdnet/td/net/Wget.cpp
new file mode 100644
index 0000000000..b30128be32
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/Wget.cpp
@@ -0,0 +1,126 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/net/Wget.h"
+
+#include "td/net/HttpHeaderCreator.h"
+#include "td/net/HttpOutboundConnection.h"
+#include "td/net/SslFd.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/HttpUrl.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/IPAddress.h"
+#include "td/utils/port/SocketFd.h"
+#include "td/utils/Slice.h"
+
+#include <limits>
+
+namespace td {
+Wget::Wget(Promise<HttpQueryPtr> promise, string url, std::vector<std::pair<string, string>> headers, int32 timeout_in,
+           int32 ttl, SslFd::VerifyPeer verify_peer)
+    : promise_(std::move(promise))
+    , input_url_(std::move(url))
+    , headers_(std::move(headers))
+    , timeout_in_(timeout_in)
+    , ttl_(ttl)
+    , verify_peer_(verify_peer) {
+}
+
+Status Wget::try_init() {
+  string input_url = input_url_;
+  TRY_RESULT(url, parse_url(MutableSlice(input_url)));
+
+  IPAddress addr;
+  TRY_STATUS(addr.init_host_port(url.host_, url.port_));
+
+  TRY_RESULT(fd, SocketFd::open(addr));
+  if (url.protocol_ == HttpUrl::Protocol::HTTP) {
+    connection_ =
+        create_actor<HttpOutboundConnection>("Connect", std::move(fd), std::numeric_limits<std::size_t>::max(), 0, 0,
+                                             ActorOwn<HttpOutboundConnection::Callback>(actor_id(this)));
+  } else {
+    TRY_RESULT(ssl_fd, SslFd::init(std::move(fd), url.host_, CSlice() /* certificate */, verify_peer_));
+    connection_ =
+        create_actor<HttpOutboundConnection>("Connect", std::move(ssl_fd), std::numeric_limits<std::size_t>::max(), 0,
+                                             0, ActorOwn<HttpOutboundConnection::Callback>(actor_id(this)));
+  }
+
+  HttpHeaderCreator hc;
+  hc.init_get(url.query_);
+  bool was_host = false;
+  for (auto &header : headers_) {
+    if (header.first == "Host") {  // TODO: lowercase
+      was_host = true;
+    }
+    hc.add_header(header.first, header.second);
+  }
+  if (!was_host) {
+    hc.add_header("Host", url.host_);
+  }
+  hc.add_header("Accept-Encoding", "gzip, deflate");
+
+  send_closure(connection_, &HttpOutboundConnection::write_next, BufferSlice(hc.finish().ok()));
+  send_closure(connection_, &HttpOutboundConnection::write_ok);
+  return Status::OK();
+}
+
+void Wget::loop() {
+  if (connection_.empty()) {
+    auto status = try_init();
+    if (status.is_error()) {
+      return on_error(std::move(status));
+    }
+  }
+}
+
+void Wget::handle(HttpQueryPtr result) {
+  on_ok(std::move(result));
+}
+
+void Wget::on_connection_error(Status error) {
+  on_error(std::move(error));
+}
+
+void Wget::on_ok(HttpQueryPtr http_query_ptr) {
+  CHECK(promise_);
+  if (http_query_ptr->code_ == 302 && ttl_ > 0) {
+    LOG(DEBUG) << *http_query_ptr;
+    input_url_ = http_query_ptr->header("location").str();
+    LOG(DEBUG) << input_url_;
+    ttl_--;
+    connection_.reset();
+    yield();
+  } else if (http_query_ptr->code_ >= 200 && http_query_ptr->code_ < 300) {
+    promise_.set_value(std::move(http_query_ptr));
+    stop();
+  } else {
+    on_error(Status::Error(PSLICE() << "http error: " << http_query_ptr->code_));
+  }
+}
+
+void Wget::on_error(Status error) {
+  CHECK(error.is_error());
+  CHECK(promise_);
+  promise_.set_error(std::move(error));
+  stop();
+}
+
+void Wget::start_up() {
+  set_timeout_in(timeout_in_);
+  loop();
+}
+
+void Wget::timeout_expired() {
+  on_error(Status::Error("Timeout expired"));
+}
+
+void Wget::tear_down() {
+  if (promise_) {
+    on_error(Status::Error("Cancelled"));
+  }
+}
+}  // namespace td
diff --git a/libs/tdlib/td/tdnet/td/net/Wget.h b/libs/tdlib/td/tdnet/td/net/Wget.h
new file mode 100644
index 0000000000..cecb113c94
--- /dev/null
+++ b/libs/tdlib/td/tdnet/td/net/Wget.h
@@ -0,0 +1,48 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/net/HttpOutboundConnection.h"
+#include "td/net/HttpQuery.h"
+#include "td/net/SslFd.h"
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Status.h"
+
+#include <utility>
+
+namespace td {
+
+class Wget : public HttpOutboundConnection::Callback {
+ public:
+  explicit Wget(Promise<HttpQueryPtr> promise, string url, std::vector<std::pair<string, string>> headers = {},
+                int32 timeout_in = 10, int32 ttl = 3, SslFd::VerifyPeer verify_peer = SslFd::VerifyPeer::On);
+
+ private:
+  Status try_init();
+  void loop() override;
+  void handle(HttpQueryPtr result) override;
+  void on_connection_error(Status error) override;
+  void on_ok(HttpQueryPtr http_query_ptr);
+  void on_error(Status error);
+
+  void tear_down() override;
+  void start_up() override;
+  void timeout_expired() override;
+
+  Promise<HttpQueryPtr> promise_;
+  ActorOwn<HttpOutboundConnection> connection_;
+  string input_url_;
+  std::vector<std::pair<string, string>> headers_;
+  int32 timeout_in_;
+  int32 ttl_;
+  SslFd::VerifyPeer verify_peer_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/CMakeLists.txt b/libs/tdlib/td/tdtl/CMakeLists.txt
new file mode 100644
index 0000000000..b0f83cd98d
--- /dev/null
+++ b/libs/tdlib/td/tdtl/CMakeLists.txt
@@ -0,0 +1,29 @@
+cmake_minimum_required(VERSION 3.0.2 FATAL_ERROR)
+
+#SOURCE SETS
+set(TDTL_SOURCE
+  td/tl/tl_config.cpp
+  td/tl/tl_core.cpp
+  td/tl/tl_file_outputer.cpp
+  td/tl/tl_file_utils.cpp
+  td/tl/tl_generate.cpp
+  td/tl/tl_outputer.cpp
+  td/tl/tl_string_outputer.cpp
+  td/tl/tl_writer.cpp
+
+  td/tl/tl_config.h
+  td/tl/tl_core.h
+  td/tl/tl_file_outputer.h
+  td/tl/tl_file_utils.h
+  td/tl/tl_generate.h
+  td/tl/tl_outputer.h
+  td/tl/tl_simple.h
+  td/tl/tl_simple_parser.h
+  td/tl/tl_string_outputer.h
+  td/tl/tl_writer.h
+)
+
+add_library(tdtl STATIC ${TDTL_SOURCE})
+target_include_directories(tdtl PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>)
+#TODO
+#target_compile_options(tdtl PRIVATE "-std=c++03")
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_config.cpp b/libs/tdlib/td/tdtl/td/tl/tl_config.cpp
new file mode 100644
index 0000000000..e796596760
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_config.cpp
@@ -0,0 +1,363 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_config.h"
+
+#include <cassert>
+#include <cstdio>
+#include <cstdlib>
+
+namespace td {
+namespace tl {
+
+const std::int32_t TLS_SCHEMA_V2 = 0x3a2f9be2;
+const std::int32_t TLS_SCHEMA_V3 = 0xe4a8604b;
+const std::int32_t TLS_SCHEMA_V4 = 0x90ac88d7;
+const std::int32_t TLS_TYPE = 0x12eb4386;
+const std::int32_t TLS_COMBINATOR = 0x5c0a1ed5;
+const std::int32_t TLS_COMBINATOR_LEFT_BUILTIN = 0xcd211f63;
+const std::int32_t TLS_COMBINATOR_LEFT = 0x4c12c6d9;
+const std::int32_t TLS_COMBINATOR_RIGHT_V2 = 0x2c064372;
+const std::int32_t TLS_ARG_V2 = 0x29dfe61b;
+
+const std::int32_t TLS_EXPR_NAT = 0xdcb49bd8;
+const std::int32_t TLS_EXPR_TYPE = 0xecc9da78;
+
+const std::int32_t TLS_NAT_CONST_OLD = 0xdcb49bd8;
+const std::int32_t TLS_NAT_CONST = 0x8ce940b1;
+const std::int32_t TLS_NAT_VAR = 0x4e8a14f0;
+const std::int32_t TLS_TYPE_VAR = 0x0142ceae;
+const std::int32_t TLS_ARRAY = 0xd9fb20de;
+const std::int32_t TLS_TYPE_EXPR = 0xc1863d08;
+
+void tl_config::add_type(tl_type *type) {
+  types.push_back(type);
+  id_to_type[type->id] = type;
+  name_to_type[type->name] = type;
+}
+
+tl_type *tl_config::get_type(std::int32_t type_id) const {
+  auto it = id_to_type.find(type_id);
+  assert(it != id_to_type.end());
+  return it->second;
+}
+
+tl_type *tl_config::get_type(const std::string &type_name) {
+  return name_to_type[type_name];
+}
+
+void tl_config::add_function(tl_combinator *function) {
+  functions.push_back(function);
+  id_to_function[function->id] = function;
+  name_to_function[function->name] = function;
+}
+
+tl_combinator *tl_config::get_function(std::int32_t function_id) {
+  return id_to_function[function_id];
+}
+
+tl_combinator *tl_config::get_function(const std::string &function_name) {
+  return name_to_function[function_name];
+}
+
+std::size_t tl_config::get_type_count() const {
+  return types.size();
+}
+
+tl_type *tl_config::get_type_by_num(std::size_t num) const {
+  return types[num];
+}
+
+std::size_t tl_config::get_function_count() const {
+  return functions.size();
+}
+
+tl_combinator *tl_config::get_function_by_num(std::size_t num) const {
+  return functions[num];
+}
+
+std::int32_t tl_config_parser::try_parse_int() {
+  return try_parse(p.fetch_int());
+}
+
+std::int64_t tl_config_parser::try_parse_long() {
+  return try_parse(p.fetch_long());
+}
+
+std::string tl_config_parser::try_parse_string() {
+  return try_parse(p.fetch_string());
+}
+
+template <class T>
+T tl_config_parser::try_parse(const T &res) const {
+  if (p.get_error() != NULL) {
+    std::fprintf(stderr, "Wrong TL-scheme specified: %s at %d\n", p.get_error(), static_cast<int>(p.get_error_pos()));
+    std::abort();
+  }
+
+  return res;
+}
+
+int tl_config_parser::get_schema_version(std::int32_t version_id) {
+  if (version_id == TLS_SCHEMA_V4) {
+    return 4;
+  }
+  if (version_id == TLS_SCHEMA_V3) {
+    return 3;
+  }
+  if (version_id == TLS_SCHEMA_V2) {
+    return 2;
+  }
+  return -1;
+}
+
+tl_tree *tl_config_parser::read_num_const() {
+  int num = static_cast<int>(try_parse_int());
+
+  return new tl_tree_nat_const(FLAG_NOVAR, num);
+}
+
+tl_tree *tl_config_parser::read_num_var(int *var_count) {
+  std::int32_t diff = try_parse_int();
+  int var_num = static_cast<int>(try_parse_int());
+
+  if (var_num >= *var_count) {
+    *var_count = var_num + 1;
+  }
+
+  return new tl_tree_var_num(0, var_num, diff);
+}
+
+tl_tree *tl_config_parser::read_type_var(int *var_count) {
+  int var_num = static_cast<int>(try_parse_int());
+  std::int32_t flags = try_parse_int();
+
+  if (var_num >= *var_count) {
+    *var_count = var_num + 1;
+  }
+  assert(!(flags & (FLAG_NOVAR | FLAG_BARE)));
+
+  return new tl_tree_var_type(flags, var_num);
+}
+
+tl_tree *tl_config_parser::read_array(int *var_count) {
+  std::int32_t flags = FLAG_NOVAR;
+  tl_tree *multiplicity = read_nat_expr(var_count);
+
+  tl_tree_array *T = new tl_tree_array(flags, multiplicity, read_args_list(var_count));
+
+  for (std::size_t i = 0; i < T->args.size(); i++) {
+    if (!(T->args[i].flags & FLAG_NOVAR)) {
+      T->flags &= ~FLAG_NOVAR;
+    }
+  }
+  return T;
+}
+
+tl_tree *tl_config_parser::read_type(int *var_count) {
+  tl_type *type = config.get_type(try_parse_int());
+  assert(type != NULL);
+  std::int32_t flags = try_parse_int() | FLAG_NOVAR;
+  int arity = static_cast<int>(try_parse_int());
+  assert(type->arity == arity);
+
+  tl_tree_type *T = new tl_tree_type(flags, type, arity);
+  for (std::int32_t i = 0; i < arity; i++) {
+    tl_tree *child = read_expr(var_count);
+
+    T->children[i] = child;
+    if (!(child->flags & FLAG_NOVAR)) {
+      T->flags &= ~FLAG_NOVAR;
+    }
+  }
+  return T;
+}
+
+tl_tree *tl_config_parser::read_type_expr(int *var_count) {
+  std::int32_t tree_type = try_parse_int();
+  switch (tree_type) {
+    case TLS_TYPE_VAR:
+      return read_type_var(var_count);
+    case TLS_TYPE_EXPR:
+      return read_type(var_count);
+    case TLS_ARRAY:
+      return read_array(var_count);
+    default:
+      std::fprintf(stderr, "tree_type = %d\n", static_cast<int>(tree_type));
+      std::abort();
+  }
+}
+
+tl_tree *tl_config_parser::read_nat_expr(int *var_count) {
+  std::int32_t tree_type = try_parse_int();
+  switch (tree_type) {
+    case TLS_NAT_CONST_OLD:
+    case TLS_NAT_CONST:
+      return read_num_const();
+    case TLS_NAT_VAR:
+      return read_num_var(var_count);
+    default:
+      std::fprintf(stderr, "tree_type = %d\n", static_cast<int>(tree_type));
+      std::abort();
+  }
+}
+
+tl_tree *tl_config_parser::read_expr(int *var_count) {
+  std::int32_t tree_type = try_parse_int();
+  switch (tree_type) {
+    case TLS_EXPR_NAT:
+      return read_nat_expr(var_count);
+    case TLS_EXPR_TYPE:
+      return read_type_expr(var_count);
+    default:
+      std::fprintf(stderr, "tree_type = %d\n", static_cast<int>(tree_type));
+      std::abort();
+  }
+}
+
+std::vector<arg> tl_config_parser::read_args_list(int *var_count) {
+  const int schema_flag_opt_field = 2 << static_cast<int>(schema_version >= 3);
+  const int schema_flag_has_vars = schema_flag_opt_field ^ 6;
+
+  std::size_t args_num = static_cast<size_t>(try_parse_int());
+  std::vector<arg> args(args_num);
+  for (std::size_t i = 0; i < args_num; i++) {
+    arg cur_arg;
+
+    std::int32_t arg_v = try_parse_int();
+    if (arg_v != TLS_ARG_V2) {
+      std::fprintf(stderr, "Wrong tls_arg magic %d\n", static_cast<int>(arg_v));
+      std::abort();
+    }
+
+    cur_arg.name = try_parse_string();
+    cur_arg.flags = try_parse_int();
+
+    bool is_optional = false;
+    if (cur_arg.flags & schema_flag_opt_field) {
+      cur_arg.flags &= ~schema_flag_opt_field;
+      is_optional = true;
+    }
+    if (cur_arg.flags & schema_flag_has_vars) {
+      cur_arg.flags &= ~schema_flag_has_vars;
+      cur_arg.var_num = static_cast<int>(try_parse_int());
+    } else {
+      cur_arg.var_num = -1;
+    }
+
+    if (cur_arg.var_num >= *var_count) {
+      *var_count = cur_arg.var_num + 1;
+    }
+    if (is_optional) {
+      cur_arg.exist_var_num = static_cast<int>(try_parse_int());
+      cur_arg.exist_var_bit = static_cast<int>(try_parse_int());
+    } else {
+      cur_arg.exist_var_num = -1;
+      cur_arg.exist_var_bit = 0;
+    }
+    cur_arg.type = read_type_expr(var_count);
+    if (/*cur_arg.var_num < 0 && cur_arg.exist_var_num < 0 && */ (cur_arg.type->flags & FLAG_NOVAR)) {
+      cur_arg.flags |= FLAG_NOVAR;
+    }
+
+    args[i] = cur_arg;
+  }
+  return args;
+}
+
+tl_combinator *tl_config_parser::read_combinator() {
+  std::int32_t t = try_parse_int();
+  if (t != TLS_COMBINATOR) {
+    std::fprintf(stderr, "Wrong tls_combinator magic %d\n", static_cast<int>(t));
+    std::abort();
+  }
+
+  tl_combinator *combinator = new tl_combinator();
+  combinator->id = try_parse_int();
+  combinator->name = try_parse_string();
+  combinator->type_id = try_parse_int();
+  combinator->var_count = 0;
+
+  std::int32_t left_type = try_parse_int();
+  if (left_type == TLS_COMBINATOR_LEFT) {
+    combinator->args = read_args_list(&combinator->var_count);
+  } else {
+    if (left_type != TLS_COMBINATOR_LEFT_BUILTIN) {
+      std::fprintf(stderr, "Wrong tls_combinator_left magic %d\n", static_cast<int>(left_type));
+      std::abort();
+    }
+  }
+
+  std::int32_t right_ver = try_parse_int();
+  if (right_ver != TLS_COMBINATOR_RIGHT_V2) {
+    std::fprintf(stderr, "Wrong tls_combinator_right magic %d\n", static_cast<int>(right_ver));
+    std::abort();
+  }
+  combinator->result = read_type_expr(&combinator->var_count);
+
+  return combinator;
+}
+
+tl_type *tl_config_parser::read_type() {
+  std::int32_t t = try_parse_int();
+  if (t != TLS_TYPE) {
+    std::fprintf(stderr, "Wrong tls_type magic %d\n", t);
+    std::abort();
+  }
+
+  tl_type *type = new tl_type();
+  type->id = try_parse_int();
+  type->name = try_parse_string();
+  type->constructors_num = static_cast<std::size_t>(try_parse_int());
+  type->constructors.reserve(type->constructors_num);
+  type->flags = try_parse_int();
+  type->flags &= ~(1 | 8 | 16 | 1024);
+  if (type->flags != 0) {
+    std::fprintf(stderr, "Type %s has non-zero flags: %d\n", type->name.c_str(), static_cast<int>(type->flags));
+  }
+  type->arity = static_cast<int>(try_parse_int());
+
+  try_parse_long();  // unused
+  return type;
+}
+
+tl_config tl_config_parser::parse_config() {
+  schema_version = get_schema_version(try_parse_int());
+  if (schema_version < 2) {
+    std::fprintf(stderr, "Unsupported tl-schema verdion %d\n", static_cast<int>(schema_version));
+    std::abort();
+  }
+
+  try_parse_int();  // date
+  try_parse_int();  // version
+
+  std::int32_t types_n = try_parse_int();
+  std::size_t constructors_total = 0;
+  for (std::int32_t i = 0; i < types_n; i++) {
+    tl_type *type = read_type();
+    config.add_type(type);
+    constructors_total += type->constructors_num;
+  }
+
+  std::int32_t constructors_n = try_parse_int();
+  assert(static_cast<std::size_t>(constructors_n) == constructors_total);
+  for (std::int32_t i = 0; i < constructors_n; i++) {
+    tl_combinator *constructor = read_combinator();
+    config.get_type(constructor->type_id)->add_constructor(constructor);
+  }
+
+  std::int32_t functions_n = try_parse_int();
+  for (std::int32_t i = 0; i < functions_n; i++) {
+    config.add_function(read_combinator());
+  }
+  p.fetch_end();
+  try_parse(0);
+
+  return config;
+}
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_config.h b/libs/tdlib/td/tdtl/td/tl/tl_config.h
new file mode 100644
index 0000000000..6a25a9cd09
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_config.h
@@ -0,0 +1,87 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "tl_core.h"
+#include "tl_simple_parser.h"
+
+#include <cstddef>
+#include <cstdint>
+#include <map>
+#include <string>
+#include <vector>
+
+namespace td {
+namespace tl {
+
+class tl_config {
+  std::vector<tl_type *> types;
+  std::map<std::int32_t, tl_type *> id_to_type;
+  std::map<std::string, tl_type *> name_to_type;
+
+  std::vector<tl_combinator *> functions;
+  std::map<std::int32_t, tl_combinator *> id_to_function;
+  std::map<std::string, tl_combinator *> name_to_function;
+
+ public:
+  void add_type(tl_type *type);
+
+  tl_type *get_type(std::int32_t type_id) const;
+
+  tl_type *get_type(const std::string &type_name);
+
+  void add_function(tl_combinator *function);
+
+  tl_combinator *get_function(std::int32_t function_id);
+
+  tl_combinator *get_function(const std::string &function_name);
+
+  std::size_t get_type_count() const;
+
+  tl_type *get_type_by_num(std::size_t num) const;
+
+  std::size_t get_function_count() const;
+
+  tl_combinator *get_function_by_num(std::size_t num) const;
+};
+
+class tl_config_parser {
+  tl_simple_parser p;
+  int schema_version;
+  tl_config config;
+
+  static int get_schema_version(std::int32_t version_id);
+
+  tl_tree *read_num_const();
+  tl_tree *read_num_var(int *var_count);
+  tl_tree *read_type_var(int *var_count);
+  tl_tree *read_array(int *var_count);
+  tl_tree *read_type(int *var_count);
+  tl_tree *read_type_expr(int *var_count);
+  tl_tree *read_nat_expr(int *var_count);
+  tl_tree *read_expr(int *var_count);
+  std::vector<arg> read_args_list(int *var_count);
+
+  tl_combinator *read_combinator();
+  tl_type *read_type();
+
+  template <class T>
+  T try_parse(const T &res) const;
+
+  std::int32_t try_parse_int();
+  std::int64_t try_parse_long();
+  std::string try_parse_string();
+
+ public:
+  tl_config_parser(const char *s, std::size_t len) : p(s, len) {
+  }
+
+  tl_config parse_config();
+};
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_core.cpp b/libs/tdlib/td/tdtl/td/tl/tl_core.cpp
new file mode 100644
index 0000000000..f8aa6eb10d
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_core.cpp
@@ -0,0 +1,21 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_core.h"
+
+#include <cassert>
+
+namespace td {
+namespace tl {
+
+void tl_type::add_constructor(tl_combinator *new_constructor) {
+  constructors.push_back(new_constructor);
+
+  assert(constructors.size() <= constructors_num);
+}
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_core.h b/libs/tdlib/td/tdtl/td/tl/tl_core.h
new file mode 100644
index 0000000000..04fabe1168
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_core.h
@@ -0,0 +1,159 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include <cstddef>
+#include <cstdint>
+#include <string>
+#include <vector>
+
+namespace td {
+namespace tl {
+
+const int NODE_TYPE_TYPE = 1;
+const int NODE_TYPE_NAT_CONST = 2;
+const int NODE_TYPE_VAR_TYPE = 3;
+const int NODE_TYPE_VAR_NUM = 4;
+const int NODE_TYPE_ARRAY = 5;
+
+const std::int32_t ID_VAR_NUM = 0x70659eff;
+const std::int32_t ID_VAR_TYPE = 0x2cecf817;
+const std::int32_t ID_INT = 0xa8509bda;
+const std::int32_t ID_LONG = 0x22076cba;
+const std::int32_t ID_DOUBLE = 0x2210c154;
+const std::int32_t ID_STRING = 0xb5286e24;
+const std::int32_t ID_VECTOR = 0x1cb5c415;
+const std::int32_t ID_DICTIONARY = 0x1f4c618f;
+const std::int32_t ID_MAYBE_TRUE = 0x3f9c8ef8;
+const std::int32_t ID_MAYBE_FALSE = 0x27930a7b;
+const std::int32_t ID_BOOL_FALSE = 0xbc799737;
+const std::int32_t ID_BOOL_TRUE = 0x997275b5;
+
+const std::int32_t FLAG_OPT_VAR = (1 << 17);
+const std::int32_t FLAG_EXCL = (1 << 18);
+const std::int32_t FLAG_NOVAR = (1 << 21);
+const std::int32_t FLAG_DEFAULT_CONSTRUCTOR = (1 << 25);
+const std::int32_t FLAG_BARE = (1 << 0);
+const std::int32_t FLAG_COMPLEX = (1 << 1);
+const std::int32_t FLAGS_MASK = ((1 << 16) - 1);
+
+class tl_combinator;
+
+class tl_tree;
+
+class tl_type {
+ public:
+  std::int32_t id;
+  std::string name;
+  int arity;
+  std::int32_t flags;
+  int simple_constructors;
+  std::size_t constructors_num;
+  std::vector<tl_combinator *> constructors;
+
+  void add_constructor(tl_combinator *new_constructor);
+};
+
+class arg {
+ public:
+  std::string name;
+  std::int32_t flags;
+  int var_num;
+  int exist_var_num;
+  int exist_var_bit;
+  tl_tree *type;
+};
+
+class tl_combinator {
+ public:
+  std::int32_t id;
+  std::string name;
+  int var_count;
+  std::int32_t type_id;
+  std::vector<arg> args;
+  tl_tree *result;
+};
+
+class tl_tree {
+ public:
+  std::int32_t flags;
+
+  explicit tl_tree(std::int32_t flags) : flags(flags) {
+  }
+
+  virtual int get_type() const = 0;
+
+  virtual ~tl_tree() {
+  }
+};
+
+class tl_tree_type : public tl_tree {
+ public:
+  tl_type *type;
+  std::vector<tl_tree *> children;
+
+  tl_tree_type(std::int32_t flags, tl_type *type, int child_count) : tl_tree(flags), type(type), children(child_count) {
+  }
+
+  virtual int get_type() const {
+    return NODE_TYPE_TYPE;
+  }
+};
+
+class tl_tree_nat_const : public tl_tree {
+ public:
+  int num;
+
+  tl_tree_nat_const(std::int32_t flags, int num) : tl_tree(flags), num(num) {
+  }
+
+  virtual int get_type() const {
+    return NODE_TYPE_NAT_CONST;
+  }
+};
+
+class tl_tree_var_type : public tl_tree {
+ public:
+  int var_num;
+
+  tl_tree_var_type(std::int32_t flags, int var_num) : tl_tree(flags), var_num(var_num) {
+  }
+
+  virtual int get_type() const {
+    return NODE_TYPE_VAR_TYPE;
+  }
+};
+
+class tl_tree_var_num : public tl_tree {
+ public:
+  int var_num;
+  int diff;
+
+  tl_tree_var_num(std::int32_t flags, int var_num, int diff) : tl_tree(flags), var_num(var_num), diff(diff) {
+  }
+
+  virtual int get_type() const {
+    return NODE_TYPE_VAR_NUM;
+  }
+};
+
+class tl_tree_array : public tl_tree {
+ public:
+  tl_tree *multiplicity;
+  std::vector<arg> args;
+
+  tl_tree_array(std::int32_t flags, tl_tree *multiplicity, const std::vector<arg> &a)
+      : tl_tree(flags), multiplicity(multiplicity), args(a) {
+  }
+
+  virtual int get_type() const {
+    return NODE_TYPE_ARRAY;
+  }
+};
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_file_outputer.cpp b/libs/tdlib/td/tdtl/td/tl/tl_file_outputer.cpp
new file mode 100644
index 0000000000..046a1ce84e
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_file_outputer.cpp
@@ -0,0 +1,41 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_file_outputer.h"
+
+#include <cassert>
+
+namespace td {
+namespace tl {
+
+void tl_file_outputer::append(const std::string &str) {
+  assert(f != NULL);
+  std::fprintf(f, "%s", str.c_str());
+}
+
+tl_file_outputer::tl_file_outputer() : f(NULL) {
+}
+
+void tl_file_outputer::close() {
+  if (f) {
+    std::fclose(f);
+  }
+}
+
+bool tl_file_outputer::open(const std::string &file_name) {
+  close();
+
+  f = std::fopen(file_name.c_str(), "w");
+
+  return (f != NULL);
+}
+
+tl_file_outputer::~tl_file_outputer() {
+  close();
+}
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_file_outputer.h b/libs/tdlib/td/tdtl/td/tl/tl_file_outputer.h
new file mode 100644
index 0000000000..3b9c66caaf
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_file_outputer.h
@@ -0,0 +1,33 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "tl_outputer.h"
+
+#include <cstdio>
+#include <string>
+
+namespace td {
+namespace tl {
+
+class tl_file_outputer : public tl_outputer {
+  FILE *f;
+
+  void close();
+
+ public:
+  tl_file_outputer();
+
+  bool open(const std::string &file_name);
+
+  virtual void append(const std::string &str);
+
+  virtual ~tl_file_outputer();
+};
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_file_utils.cpp b/libs/tdlib/td/tdtl/td/tl/tl_file_utils.cpp
new file mode 100644
index 0000000000..bc79d7254e
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_file_utils.cpp
@@ -0,0 +1,92 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_file_utils.h"
+
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+
+namespace td {
+namespace tl {
+
+std::string get_file_contents(const std::string &file_name, const std::string &mode) {
+  FILE *f = std::fopen(file_name.c_str(), mode.c_str());
+  if (f == NULL) {
+    return std::string();
+  }
+
+  int fseek_res = std::fseek(f, 0, SEEK_END);
+  if (fseek_res != 0) {
+    std::fprintf(stderr, "Can't seek to the end of the file \"%s\"", file_name.c_str());
+    std::abort();
+  }
+  long size_long = std::ftell(f);
+  if (size_long < 0 || size_long >= (1 << 25)) {
+    std::fprintf(stderr, "Wrong file \"%s\" has wrong size = %ld", file_name.c_str(), size_long);
+    std::abort();
+  }
+  std::size_t size = static_cast<std::size_t>(size_long);
+
+  std::string result(size, ' ');
+  std::rewind(f);
+  std::size_t fread_res = std::fread(&result[0], size, 1, f);
+  if (size != 0 && fread_res != 1) {
+    std::fprintf(stderr, "Can't read file \"%s\"", file_name.c_str());
+    std::abort();
+  }
+  std::fclose(f);
+
+  return result;
+}
+
+bool put_file_contents(const std::string &file_name, const std::string &mode, const std::string &contents) {
+  FILE *f = std::fopen(file_name.c_str(), mode.c_str());
+  if (f == NULL) {
+    std::fprintf(stderr, "Can't open file \"%s\"\n", file_name.c_str());
+    return false;
+  }
+
+  std::size_t fwrite_res = std::fwrite(contents.c_str(), contents.size(), 1, f);
+  if (fwrite_res != 1) {
+    std::fclose(f);
+    return false;
+  }
+  if (std::fclose(f) != 0) {
+    return false;
+  }
+  return true;
+}
+
+std::string remove_documentation(const std::string &str) {
+  std::size_t line_begin = 0;
+  std::string result;
+  bool inside_documentation = false;
+  while (line_begin < str.size()) {
+    std::size_t line_end = str.find('\n', line_begin);
+    if (line_end == std::string::npos) {
+      line_end = str.size() - 1;
+    }
+    std::string line = str.substr(line_begin, line_end - line_begin + 1);
+    line_begin = line_end + 1;
+
+    std::size_t pos = line.find_first_not_of(' ');
+    if (pos != std::string::npos && ((line[pos] == '/' && line[pos + 1] == '/' && line[pos + 2] == '/') ||
+                                     (line[pos] == '/' && line[pos + 1] == '*' && line[pos + 2] == '*') ||
+                                     (inside_documentation && line[pos] == '*'))) {
+      inside_documentation = !(line[pos] == '/' && line[pos + 1] == '/' && line[pos + 2] == '/') &&
+                             !(line[pos] == '*' && line[pos + 1] == '/');
+      continue;
+    }
+
+    inside_documentation = false;
+    result += line;
+  }
+  return result;
+}
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_file_utils.h b/libs/tdlib/td/tdtl/td/tl/tl_file_utils.h
new file mode 100644
index 0000000000..50e40b4418
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_file_utils.h
@@ -0,0 +1,21 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include <string>
+
+namespace td {
+namespace tl {
+
+std::string get_file_contents(const std::string &file_name, const std::string &mode);
+
+bool put_file_contents(const std::string &file_name, const std::string &mode, const std::string &contents);
+
+std::string remove_documentation(const std::string &str);
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_generate.cpp b/libs/tdlib/td/tdtl/td/tl/tl_generate.cpp
new file mode 100644
index 0000000000..401d451cd6
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_generate.cpp
@@ -0,0 +1,843 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_generate.h"
+
+#include "tl_config.h"
+#include "tl_core.h"
+#include "tl_file_utils.h"
+#include "tl_outputer.h"
+#include "tl_string_outputer.h"
+#include "tl_writer.h"
+
+#include <cassert>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <set>
+#include <string>
+#include <vector>
+
+namespace td {
+namespace tl {
+
+static bool is_reachable_for_parser(int parser_type, const std::string &name,
+                                    const std::set<std::string> &request_types,
+                                    const std::set<std::string> &result_types, const TL_writer &w) {
+  TL_writer::Mode mode = w.get_parser_mode(parser_type);
+  if (mode == TL_writer::Client) {
+    return result_types.count(name) > 0;
+  }
+  if (mode == TL_writer::Server) {
+    return request_types.count(name) > 0;
+  }
+  return true;
+}
+
+static bool is_reachable_for_storer(int storer_type, const std::string &name,
+                                    const std::set<std::string> &request_types,
+                                    const std::set<std::string> &result_types, const TL_writer &w) {
+  TL_writer::Mode mode = w.get_storer_mode(storer_type);
+  if (mode == TL_writer::Client) {
+    return request_types.count(name) > 0;
+  }
+  if (mode == TL_writer::Server) {
+    return result_types.count(name) > 0;
+  }
+  return true;
+}
+
+static void write_class_constructor(tl_outputer &out, const tl_combinator *t, const std::string &class_name,
+                                    bool is_default, const TL_writer &w) {
+  //  std::fprintf(stderr, "Gen constructor %s\n", class_name.c_str());
+  int fields_num = 0;
+  for (std::size_t i = 0; i < t->args.size(); i++) {
+    fields_num += !w.gen_constructor_parameter(0, class_name, t->args[i], is_default).empty();
+  }
+
+  out.append(w.gen_constructor_begin(fields_num, class_name, is_default));
+  int field_num = 0;
+  for (std::size_t i = 0; i < t->args.size(); i++) {
+    std::string parameter_init = w.gen_constructor_parameter(field_num, class_name, t->args[i], is_default);
+    if (parameter_init.size()) {
+      out.append(parameter_init);
+      field_num++;
+    }
+  }
+  assert(field_num == fields_num);
+
+  field_num = 0;
+  for (std::size_t i = 0; i < t->args.size(); i++) {
+    std::string field_init = w.gen_constructor_field_init(field_num, class_name, t->args[i], is_default);
+    if (field_init.size()) {
+      out.append(field_init);
+      field_num++;
+    }
+  }
+
+  out.append(w.gen_constructor_end(t, field_num, is_default));
+}
+
+static void write_function_fetch(tl_outputer &out, const std::string &parser_name, const tl_combinator *t,
+                                 const std::string &class_name, const std::set<std::string> &request_types,
+                                 const std::set<std::string> &result_types, const TL_writer &w) {
+  //  std::fprintf(stderr, "Write function fetch %s\n", class_name.c_str());
+  std::vector<var_description> vars(t->var_count);
+  int parser_type = w.get_parser_type(t, parser_name);
+
+  if (!is_reachable_for_parser(parser_type, t->name, request_types, result_types, w)) {
+    return;
+  }
+
+  out.append(w.gen_fetch_function_begin(parser_name, class_name, 0, vars, parser_type));
+  out.append(w.gen_vars(t, NULL, vars));
+  int field_num = 0;
+  for (std::size_t i = 0; i < t->args.size(); i++) {
+    std::string field_fetch = w.gen_field_fetch(field_num, t->args[i], vars, false, parser_type);
+    if (field_fetch.size()) {
+      out.append(field_fetch);
+      field_num++;
+    }
+  }
+
+  out.append(w.gen_fetch_function_end(field_num, vars, parser_type));
+}
+
+static std::vector<var_description> write_function_store(tl_outputer &out, const std::string &storer_name,
+                                                         const tl_combinator *t, const std::string &class_name,
+                                                         std::vector<var_description> &vars,
+                                                         const std::set<std::string> &request_types,
+                                                         const std::set<std::string> &result_types,
+                                                         const TL_writer &w) {
+  //  std::fprintf(stderr, "Write function store %s\n", class_name.c_str());
+  int storer_type = w.get_storer_type(t, storer_name);
+
+  if (!is_reachable_for_storer(storer_type, t->name, request_types, result_types, w)) {
+    return vars;
+  }
+
+  out.append(w.gen_store_function_begin(storer_name, class_name, 0, vars, storer_type));
+  out.append(w.gen_constructor_id_store(t->id, storer_type));
+  for (std::size_t i = 0; i < t->args.size(); i++) {
+    out.append(w.gen_field_store(t->args[i], vars, false, storer_type));
+  }
+
+  out.append(w.gen_store_function_end(vars, storer_type));
+
+  return vars;
+}
+
+static void write_function_result_fetch(tl_outputer &out, const std::string &parser_name, const tl_combinator *t,
+                                        const std::string &class_name, const tl_tree *result,
+                                        const std::vector<var_description> &vars, const TL_writer &w) {
+  //  std::fprintf(stderr, "Write function result fetch %s\n", class_name.c_str());
+  int parser_type = w.get_parser_type(t, parser_name);
+
+  out.append(w.gen_fetch_function_result_begin(parser_name, class_name, result));
+
+  if (result->get_type() == NODE_TYPE_VAR_TYPE) {
+    const tl_tree_var_type *result_var_type = static_cast<const tl_tree_var_type *>(result);
+
+    for (std::size_t i = 0; i < t->args.size(); i++) {
+      const arg &a = t->args[i];
+
+      int arg_type = a.type->get_type();
+      if (arg_type == NODE_TYPE_VAR_TYPE) {
+        const tl_tree_var_type *tree_var_type = static_cast<const tl_tree_var_type *>(a.type);
+        assert(a.flags & FLAG_EXCL);
+        assert(tree_var_type->var_num >= 0);
+        if (tree_var_type->var_num == result_var_type->var_num) {
+          out.append(w.gen_var_type_fetch(a));
+        }
+      }
+    }
+  } else {
+    assert(result->get_type() == NODE_TYPE_TYPE);
+    const tl_tree_type *result_type = static_cast<const tl_tree_type *>(result);
+    out.append(w.gen_type_fetch("", result_type, vars, parser_type));
+  }
+
+  out.append(w.gen_fetch_function_result_end());
+
+  out.append(w.gen_fetch_function_result_any_begin(parser_name, class_name, false));
+  out.append(w.gen_fetch_function_result_any_end(false));
+}
+
+static void write_constructor_fetch(tl_outputer &out, const std::string &parser_name, const tl_combinator *t,
+                                    const std::string &class_name, const tl_tree_type *result_type, bool is_flat,
+                                    const std::set<std::string> &request_types,
+                                    const std::set<std::string> &result_types, const TL_writer &w) {
+  std::vector<var_description> vars(t->var_count);
+
+  int parser_type = w.get_parser_type(t, parser_name);
+
+  if (!is_reachable_for_parser(parser_type, t->name, request_types, result_types, w)) {
+    return;
+  }
+
+  out.append(w.gen_fetch_function_begin(parser_name, class_name, static_cast<int>(result_type->children.size()), vars,
+                                        parser_type));
+  out.append(w.gen_vars(t, result_type, vars));
+  out.append(w.gen_uni(result_type, vars, true));
+  int field_num = 0;
+  for (std::size_t i = 0; i < t->args.size(); i++) {
+    std::string field_fetch = w.gen_field_fetch(field_num, t->args[i], vars, is_flat, parser_type);
+    if (field_fetch.size()) {
+      out.append(field_fetch);
+      field_num++;
+    }
+  }
+
+  out.append(w.gen_fetch_function_end(field_num, vars, parser_type));
+}
+
+static void write_constructor_store(tl_outputer &out, const std::string &storer_name, const tl_combinator *t,
+                                    const std::string &class_name, const tl_tree_type *result_type, bool is_flat,
+                                    const std::set<std::string> &request_types,
+                                    const std::set<std::string> &result_types, const TL_writer &w) {
+  std::vector<var_description> vars(t->var_count);
+  int storer_type = w.get_storer_type(t, storer_name);
+
+  if (!is_reachable_for_storer(storer_type, t->name, request_types, result_types, w)) {
+    return;
+  }
+
+  out.append(w.gen_store_function_begin(storer_name, class_name, static_cast<int>(result_type->children.size()), vars,
+                                        storer_type));
+  out.append(w.gen_vars(t, result_type, vars));
+  out.append(w.gen_uni(result_type, vars, false));
+  for (std::size_t i = 0; i < t->args.size(); i++) {
+    //  std::fprintf(stderr, "%s: %s\n", result_type->type->name.c_str(), t->name.c_str());
+    out.append(w.gen_field_store(t->args[i], vars, is_flat, storer_type));
+  }
+
+  out.append(w.gen_store_function_end(vars, storer_type));
+}
+
+static int gen_field_definitions(tl_outputer &out, const tl_combinator *t, const std::string &class_name,
+                                 const TL_writer &w) {
+  int required_args = 0;
+
+  for (std::size_t i = 0; i < t->args.size(); i++) {
+    const arg &a = t->args[i];
+
+    assert(-1 <= a.var_num && a.var_num < t->var_count);
+
+    required_args += !(a.flags & FLAG_OPT_VAR);
+
+    if (a.flags & FLAG_OPT_VAR) {
+      //    continue;
+    }
+
+    std::string type_name = w.gen_field_type(a);
+    if (type_name.size()) {
+      out.append(w.gen_field_definition(class_name, type_name, w.gen_field_name(a.name)));
+    }
+  }
+
+  return required_args;
+}
+
+static void write_function(tl_outputer &out, const tl_combinator *t, const std::set<std::string> &request_types,
+                           const std::set<std::string> &result_types, const TL_writer &w) {
+  assert(w.is_combinator_supported(t));
+
+  std::string class_name = w.gen_class_name(t->name);
+
+  out.append(w.gen_class_begin(class_name, w.gen_base_function_class_name(), false));
+
+  int required_args = gen_field_definitions(out, t, class_name, w);
+  out.append(w.gen_flags_definitions(t));
+
+  std::vector<var_description> vars(t->var_count);
+  out.append(w.gen_function_vars(t, vars));
+
+  write_class_constructor(out, t, class_name, true, w);
+  if (required_args) {
+    write_class_constructor(out, t, class_name, false, w);
+  }
+
+  out.append(w.gen_get_id(class_name, t->id, false));
+
+  out.append(w.gen_function_result_type(t->result));
+
+  //  PARSER
+  std::vector<std::string> parsers = w.get_parsers();
+  for (std::size_t i = 0; i < parsers.size(); i++) {
+    write_function_fetch(out, parsers[i], t, class_name, request_types, result_types, w);
+  }
+
+  //  STORER
+  std::vector<std::string> storers = w.get_storers();
+  for (std::size_t i = 0; i < storers.size(); i++) {
+    write_function_store(out, storers[i], t, class_name, vars, request_types, result_types, w);
+  }
+
+  //  PARSE RESULT
+  for (std::size_t i = 0; i < parsers.size(); i++) {
+    if (w.get_parser_mode(-1) == TL_writer::Server) {
+      continue;
+    }
+
+    write_function_result_fetch(out, parsers[i], t, class_name, t->result, vars, w);
+  }
+
+  //  ADDITIONAL FUNCTIONS
+  std::vector<std::string> additional_functions = w.get_additional_functions();
+  for (std::size_t i = 0; i < additional_functions.size(); i++) {
+    out.append(w.gen_additional_function(additional_functions[i], t, true));
+  }
+
+  out.append(w.gen_class_end());
+}
+
+static void write_constructor(tl_outputer &out, const tl_combinator *t, const std::string &base_class, bool is_proxy,
+                              const std::set<std::string> &request_types, const std::set<std::string> &result_types,
+                              const TL_writer &w) {
+  assert(w.is_combinator_supported(t));
+
+  std::string class_name = w.gen_class_name(t->name);
+
+  out.append(w.gen_class_begin(class_name, base_class, is_proxy));
+  int required_args = gen_field_definitions(out, t, class_name, w);
+  out.append(w.gen_flags_definitions(t));
+
+  write_class_constructor(out, t, class_name, true, w);
+  if (required_args) {
+    write_class_constructor(out, t, class_name, false, w);
+  }
+
+  out.append(w.gen_get_id(class_name, t->id, false));
+
+  //  PARSER
+  assert(t->result->get_type() == NODE_TYPE_TYPE);
+  const tl_tree_type *result_type = static_cast<const tl_tree_type *>(t->result);
+
+  std::vector<std::string> parsers = w.get_parsers();
+  for (std::size_t i = 0; i < parsers.size(); i++) {
+    write_constructor_fetch(out, parsers[i], t, class_name, result_type,
+                            required_args == 1 && result_type->type->simple_constructors == 1, request_types,
+                            result_types, w);
+  }
+
+  //  STORER
+  std::vector<std::string> storers = w.get_storers();
+  for (std::size_t i = 0; i < storers.size(); i++) {
+    write_constructor_store(out, storers[i], t, class_name, result_type,
+                            required_args == 1 && result_type->type->simple_constructors == 1, request_types,
+                            result_types, w);
+  }
+
+  //  ADDITIONAL FUNCTIONS
+  std::vector<std::string> additional_functions = w.get_additional_functions();
+  for (std::size_t i = 0; i < additional_functions.size(); i++) {
+    out.append(w.gen_additional_function(additional_functions[i], t, false));
+  }
+
+  out.append(w.gen_class_end());
+}
+
+void write_class(tl_outputer &out, const tl_type *t, const std::set<std::string> &request_types,
+                 const std::set<std::string> &result_types, const TL_writer &w) {
+  assert(t->constructors_num > 0);
+  assert(!w.is_built_in_simple_type(t->name));
+  assert(!w.is_built_in_complex_type(t->name));
+  assert(!(t->flags & FLAG_COMPLEX));
+
+  assert(t->arity >= 0);
+  assert(t->simple_constructors > 0);
+  assert(t->flags == 0);
+
+  const std::string base_class = w.gen_base_type_class_name(t->arity);
+  const std::string class_name = w.gen_class_name(t->name);
+
+  std::vector<var_description> empty_vars;
+  bool optimize_one_constructor = (t->simple_constructors == 1);
+  if (!optimize_one_constructor) {
+    out.append(w.gen_class_begin(class_name, base_class, true));
+
+    out.append(w.gen_get_id(class_name, 0, true));
+
+    std::vector<std::string> parsers = w.get_parsers();
+    for (std::size_t i = 0; i < parsers.size(); i++) {
+      if (!is_reachable_for_parser(-1, t->name, request_types, result_types, w)) {
+        continue;
+      }
+
+      out.append(w.gen_fetch_function_begin(parsers[i], class_name, t->arity, empty_vars, -1));
+      out.append(w.gen_fetch_switch_begin());
+      for (std::size_t j = 0; j < t->constructors_num; j++) {
+        if (w.is_combinator_supported(t->constructors[j])) {
+          out.append(w.gen_fetch_switch_case(t->constructors[j], t->arity));
+        }
+      }
+
+      out.append(w.gen_fetch_switch_end());
+      out.append(w.gen_fetch_function_end(-1, empty_vars, -1));
+    }
+
+    std::vector<std::string> storers = w.get_storers();
+    for (std::size_t i = 0; i < storers.size(); i++) {
+      if (!is_reachable_for_storer(-1, t->name, request_types, result_types, w)) {
+        continue;
+      }
+
+      out.append(w.gen_store_function_begin(storers[i], class_name, t->arity, empty_vars, -1));
+      out.append(w.gen_store_function_end(empty_vars, -1));
+    }
+
+    std::vector<std::string> additional_functions = w.get_additional_functions();
+    for (std::size_t i = 0; i < additional_functions.size(); i++) {
+      out.append(w.gen_additional_proxy_function_begin(additional_functions[i], t, class_name, t->arity, false));
+      for (std::size_t j = 0; j < t->constructors_num; j++) {
+        if (w.is_combinator_supported(t->constructors[j])) {
+          out.append(
+              w.gen_additional_proxy_function_case(additional_functions[i], t, t->constructors[j], t->arity, false));
+        }
+      }
+
+      out.append(w.gen_additional_proxy_function_end(additional_functions[i], t, false));
+    }
+
+    out.append(w.gen_class_end());
+  }
+
+  int written_constructors = 0;
+  for (std::size_t i = 0; i < t->constructors_num; i++) {
+    if (w.is_combinator_supported(t->constructors[i])) {
+      if (optimize_one_constructor) {
+        write_constructor(out, t->constructors[i], base_class, false, request_types, result_types, w);
+        out.append(w.gen_class_alias(w.gen_class_name(t->constructors[i]->name), class_name));
+      } else {
+        write_constructor(out, t->constructors[i], class_name, false, request_types, result_types, w);
+      }
+      written_constructors++;
+    } else {
+      std::fprintf(stderr, "Skip complex constructor %s of %s\n", t->constructors[i]->name.c_str(), t->name.c_str());
+    }
+  }
+  assert(written_constructors == t->simple_constructors);
+}
+
+static void dfs_type(const tl_type *t, std::set<std::string> &found, const TL_writer &w);
+
+static void dfs_tree(const tl_tree *t, std::set<std::string> &found, const TL_writer &w) {
+  int type = t->get_type();
+
+  if (type == NODE_TYPE_ARRAY) {
+    const tl_tree_array *arr = static_cast<const tl_tree_array *>(t);
+    for (std::size_t i = 0; i < arr->args.size(); i++) {
+      dfs_tree(arr->args[i].type, found, w);
+    }
+  } else if (type == NODE_TYPE_TYPE) {
+    const tl_tree_type *tree_type = static_cast<const tl_tree_type *>(t);
+    dfs_type(tree_type->type, found, w);
+    for (std::size_t i = 0; i < tree_type->children.size(); i++) {
+      dfs_tree(tree_type->children[i], found, w);
+    }
+  } else {
+    assert(type == NODE_TYPE_VAR_TYPE);
+  }
+}
+
+static void dfs_combinator(const tl_combinator *constructor, std::set<std::string> &found, const TL_writer &w) {
+  if (!w.is_combinator_supported(constructor)) {
+    return;
+  }
+
+  if (!found.insert(constructor->name).second) {
+    return;
+  }
+
+  for (std::size_t i = 0; i < constructor->args.size(); i++) {
+    dfs_tree(constructor->args[i].type, found, w);
+  }
+}
+
+static void dfs_type(const tl_type *t, std::set<std::string> &found, const TL_writer &w) {
+  if (!found.insert(t->name).second) {
+    return;
+  }
+
+  if (t->constructors_num == 0 || w.is_built_in_simple_type(t->name) || w.is_built_in_complex_type(t->name)) {
+    return;
+  }
+
+  assert(!(t->flags & FLAG_COMPLEX));
+
+  for (std::size_t i = 0; i < t->constructors_num; i++) {
+    dfs_combinator(t->constructors[i], found, w);
+  }
+}
+
+void write_tl(const tl_config &config, tl_outputer &out, const TL_writer &w) {
+  out.append(w.gen_output_begin());
+
+  std::size_t types_n = config.get_type_count();
+  std::size_t functions_n = config.get_function_count();
+
+  bool found_complex = false;
+  for (std::size_t type = 0; type < types_n; type++) {
+    tl_type *t = config.get_type_by_num(type);
+    assert(t->constructors_num == t->constructors.size());
+    if (t->constructors_num == 0) {  // built-in dummy types
+      if (t->name == "Type") {
+        assert(t->id == ID_VAR_TYPE);
+        t->flags |= FLAG_COMPLEX;
+        found_complex = true;
+      }
+      continue;
+    }
+
+    for (std::size_t j = 0; j < t->constructors_num; j++) {
+      tl_combinator *constructor = t->constructors[j];
+      assert(constructor->type_id == t->id);
+      assert(constructor->result->get_type() == NODE_TYPE_TYPE);
+      assert(static_cast<const tl_tree_type *>(constructor->result)->type == t);
+      assert(static_cast<const tl_tree_type *>(constructor->result)->children.size() ==
+             static_cast<std::size_t>(t->arity));
+      assert(static_cast<const tl_tree_type *>(constructor->result)->flags == (t->arity > 0 ? 0 : FLAG_NOVAR));
+
+      for (std::size_t k = 0; k < constructor->args.size(); k++) {
+        const arg &a = constructor->args[k];
+
+        assert(-1 <= a.var_num && a.var_num <= constructor->var_count);
+
+        int arg_type = a.type->get_type();
+        assert(arg_type == NODE_TYPE_TYPE || arg_type == NODE_TYPE_VAR_TYPE || arg_type == NODE_TYPE_ARRAY);
+        if (a.var_num >= 0) {
+          assert(arg_type == NODE_TYPE_TYPE);
+          assert(static_cast<const tl_tree_type *>(a.type)->type->id == ID_VAR_NUM ||
+                 static_cast<const tl_tree_type *>(a.type)->type->id == ID_VAR_TYPE);
+        }
+
+        if (arg_type == NODE_TYPE_ARRAY) {
+          const tl_tree_array *arr = static_cast<const tl_tree_array *>(a.type);
+          assert(arr->multiplicity->get_type() == NODE_TYPE_NAT_CONST ||
+                 arr->multiplicity->get_type() == NODE_TYPE_VAR_NUM);
+          for (std::size_t l = 0; l < arr->args.size(); l++) {
+            const arg &b = arr->args[l];
+            int b_arg_type = b.type->get_type();
+            if (b_arg_type == NODE_TYPE_VAR_TYPE || b_arg_type == NODE_TYPE_ARRAY || b.var_num != -1 ||
+                b.exist_var_num != -1) {
+              if (!w.is_built_in_complex_type(t->name)) {
+                t->flags |= FLAG_COMPLEX;
+                found_complex = true;
+              }
+            } else {
+              assert(b_arg_type == NODE_TYPE_TYPE);
+            }
+            assert(b.flags == FLAG_NOVAR || b.flags == 0);
+          }
+        }
+      }
+    }
+
+    for (int i = 0; i < t->arity; i++) {
+      int main_type = static_cast<const tl_tree_type *>(t->constructors[0]->result)->children[i]->get_type();
+      for (std::size_t j = 1; j < t->constructors_num; j++) {
+        assert(static_cast<const tl_tree_type *>(t->constructors[j]->result)->children[i]->get_type() == main_type);
+      }
+      assert(main_type == NODE_TYPE_VAR_TYPE || main_type == NODE_TYPE_VAR_NUM);
+      if (main_type == NODE_TYPE_VAR_TYPE) {
+        if (!w.is_built_in_complex_type(t->name)) {
+          t->flags |= FLAG_COMPLEX;
+          found_complex = true;
+        }
+      }
+    }
+  }
+
+  while (found_complex) {
+    found_complex = false;
+    for (std::size_t type = 0; type < types_n; type++) {
+      tl_type *t = config.get_type_by_num(type);
+      if (t->constructors_num == 0 || w.is_built_in_complex_type(t->name)) {  // built-in dummy or complex types
+        continue;
+      }
+      if (t->flags & FLAG_COMPLEX) {  // already complex
+        continue;
+      }
+
+      t->simple_constructors = 0;
+      for (std::size_t i = 0; i < t->constructors_num; i++) {
+        t->simple_constructors += w.is_combinator_supported(t->constructors[i]);
+      }
+      if (t->simple_constructors == 0) {
+        t->flags |= FLAG_COMPLEX;
+        found_complex = true;
+        //  std::fprintf(stderr, "Found complex %s\n", t->name.c_str());
+      }
+    }
+  }
+
+  std::set<std::string> request_types;
+  std::set<std::string> result_types;
+  for (std::size_t function = 0; function < functions_n; function++) {
+    const tl_combinator *t = config.get_function_by_num(function);
+    dfs_combinator(t, request_types, w);
+    dfs_tree(t->result, result_types, w);
+  }
+
+  // write forward declarations
+  for (std::size_t type = 0; type < types_n; type++) {
+    tl_type *t = config.get_type_by_num(type);
+    if (t->constructors_num == 0 || w.is_built_in_simple_type(t->name) || w.is_built_in_complex_type(t->name) ||
+        (t->flags & FLAG_COMPLEX)) {  // built-in or complex types
+      continue;
+    }
+
+    assert(t->flags == 0);
+
+    if (t->simple_constructors != 1) {
+      out.append(w.gen_forward_class_declaration(w.gen_class_name(t->name), true));
+    } else {
+      for (std::size_t i = 0; i < t->constructors_num; i++) {
+        if (w.is_combinator_supported(t->constructors[i])) {
+          out.append(w.gen_forward_class_declaration(w.gen_class_name(t->constructors[i]->name), false));
+        }
+      }
+    }
+  }
+  for (int i = 0; i <= w.get_max_arity(); i++) {
+    out.append(w.gen_forward_class_declaration(w.gen_base_type_class_name(i), true));
+  }
+
+  for (std::size_t function = 0; function < functions_n; function++) {
+    tl_combinator *t = config.get_function_by_num(function);
+    if (!w.is_combinator_supported(t)) {
+      continue;
+    }
+
+    // out.append(w.gen_forward_class_declaration(w.gen_class_name(t->name), false));
+  }
+  // out.append(w.gen_forward_class_declaration(w.gen_base_function_class_name(), true));
+
+  // write base classes
+  std::vector<var_description> empty_vars;
+  for (int i = 0; i <= w.get_max_arity(); i++) {
+    out.append(w.gen_class_begin(w.gen_base_type_class_name(i), w.gen_base_tl_class_name(), true));
+
+    out.append(w.gen_get_id(w.gen_base_type_class_name(i), 0, true));
+
+    std::vector<std::string> parsers = w.get_parsers();
+    for (std::size_t j = 0; j < parsers.size(); j++) {
+      int case_count = 0;
+      for (std::size_t type = 0; type < types_n; type++) {
+        tl_type *t = config.get_type_by_num(type);
+        if (t->constructors_num == 0 || w.is_built_in_simple_type(t->name) || w.is_built_in_complex_type(t->name) ||
+            (t->flags & FLAG_COMPLEX)) {  // built-in or complex types
+          continue;
+        }
+        if (t->arity != i) {  // additional condition
+          continue;
+        }
+
+        for (std::size_t k = 0; k < t->constructors_num; k++) {
+          if (w.is_combinator_supported(t->constructors[k]) &&
+              is_reachable_for_parser(-1, t->constructors[k]->name, request_types, result_types, w)) {
+            case_count++;
+          }
+        }
+      }
+
+      if (case_count == 0) {
+        continue;
+      }
+
+      out.append(w.gen_fetch_function_begin(parsers[j], w.gen_base_type_class_name(i), i, empty_vars, -1));
+      out.append(w.gen_fetch_switch_begin());
+      for (std::size_t type = 0; type < types_n; type++) {
+        tl_type *t = config.get_type_by_num(type);
+        if (t->constructors_num == 0 || w.is_built_in_simple_type(t->name) || w.is_built_in_complex_type(t->name) ||
+            (t->flags & FLAG_COMPLEX)) {  // built-in or complex types
+          continue;
+        }
+        if (t->arity != i) {  // additional condition
+          continue;
+        }
+
+        for (std::size_t k = 0; k < t->constructors_num; k++) {
+          if (w.is_combinator_supported(t->constructors[k]) &&
+              is_reachable_for_parser(-1, t->constructors[k]->name, request_types, result_types, w)) {
+            out.append(w.gen_fetch_switch_case(t->constructors[k], i));
+          }
+        }
+      }
+      out.append(w.gen_fetch_switch_end());
+      out.append(w.gen_fetch_function_end(-1, empty_vars, -1));
+    }
+
+    std::vector<std::string> additional_functions = w.get_additional_functions();
+    for (std::size_t j = 0; j < additional_functions.size(); j++) {
+      out.append(w.gen_additional_proxy_function_begin(additional_functions[j], NULL, w.gen_base_type_class_name(i), i,
+                                                       false));
+      for (std::size_t type = 0; type < types_n; type++) {
+        tl_type *t = config.get_type_by_num(type);
+        if (t->constructors_num == 0 || w.is_built_in_simple_type(t->name) || w.is_built_in_complex_type(t->name) ||
+            (t->flags & FLAG_COMPLEX)) {  // built-in or complex types
+          continue;
+        }
+        if (t->arity != i) {  // additional condition
+          continue;
+        }
+
+        int function_type = w.get_additional_function_type(additional_functions[j]);
+        if ((function_type & 1) && t->simple_constructors != 1) {
+          out.append(w.gen_additional_proxy_function_case(additional_functions[j], NULL, w.gen_class_name(t->name), i));
+        }
+        if ((function_type & 2) || ((function_type & 1) && t->simple_constructors == 1)) {
+          for (std::size_t k = 0; k < t->constructors_num; k++) {
+            if (w.is_combinator_supported(t->constructors[k])) {
+              out.append(
+                  w.gen_additional_proxy_function_case(additional_functions[j], NULL, t->constructors[k], i, false));
+            }
+          }
+        }
+      }
+
+      out.append(w.gen_additional_proxy_function_end(additional_functions[j], NULL, false));
+    }
+
+    std::vector<std::string> storers = w.get_storers();
+    for (std::size_t j = 0; j < storers.size(); j++) {
+      out.append(w.gen_store_function_begin(storers[j], w.gen_base_type_class_name(i), i, empty_vars, -1));
+      out.append(w.gen_store_function_end(empty_vars, -1));
+    }
+
+    out.append(w.gen_class_end());
+  }
+
+  {
+    out.append(w.gen_class_begin(w.gen_base_function_class_name(), w.gen_base_tl_class_name(), true));
+
+    out.append(w.gen_get_id(w.gen_base_function_class_name(), 0, true));
+
+    std::vector<std::string> parsers = w.get_parsers();
+    for (std::size_t j = 0; j < parsers.size(); j++) {
+      if (w.get_parser_mode(-1) == TL_writer::Client) {
+        continue;
+      }
+
+      out.append(w.gen_fetch_function_begin(parsers[j], w.gen_base_function_class_name(), 0, empty_vars, -1));
+      out.append(w.gen_fetch_switch_begin());
+      for (std::size_t function = 0; function < functions_n; function++) {
+        tl_combinator *t = config.get_function_by_num(function);
+
+        if (w.is_combinator_supported(t)) {
+          out.append(w.gen_fetch_switch_case(t, 0));
+        }
+      }
+      out.append(w.gen_fetch_switch_end());
+      out.append(w.gen_fetch_function_end(-1, empty_vars, -1));
+    }
+
+    std::vector<std::string> storers = w.get_storers();
+    for (std::size_t j = 0; j < storers.size(); j++) {
+      if (w.get_storer_mode(-1) == TL_writer::Server) {
+        continue;
+      }
+
+      out.append(w.gen_store_function_begin(storers[j], w.gen_base_function_class_name(), 0, empty_vars, -1));
+      out.append(w.gen_store_function_end(empty_vars, -1));
+    }
+
+    for (std::size_t j = 0; j < parsers.size(); j++) {
+      if (w.get_parser_mode(-1) == TL_writer::Server) {
+        continue;
+      }
+
+      out.append(w.gen_fetch_function_result_any_begin(parsers[j], w.gen_base_function_class_name(), true));
+      out.append(w.gen_fetch_function_result_any_end(true));
+    }
+
+    std::vector<std::string> additional_functions = w.get_additional_functions();
+    for (std::size_t j = 0; j < additional_functions.size(); j++) {
+      out.append(w.gen_additional_proxy_function_begin(additional_functions[j], NULL, w.gen_base_function_class_name(),
+                                                       0, true));
+      for (std::size_t function = 0; function < functions_n; function++) {
+        tl_combinator *t = config.get_function_by_num(function);
+
+        if (w.is_combinator_supported(t)) {
+          out.append(w.gen_additional_proxy_function_case(additional_functions[j], NULL, t, 0, true));
+        }
+      }
+
+      out.append(w.gen_additional_proxy_function_end(additional_functions[j], NULL, true));
+    }
+
+    out.append(w.gen_class_end());
+  }
+
+  for (std::size_t type = 0; type < types_n; type++) {
+    tl_type *t = config.get_type_by_num(type);
+    if (t->constructors_num == 0 || w.is_built_in_simple_type(t->name) ||
+        w.is_built_in_complex_type(t->name)) {  // built-in dummy or complex types
+      continue;
+    }
+
+    if (t->flags & FLAG_COMPLEX) {
+      std::fprintf(stderr, "Can't generate class %s\n", t->name.c_str());
+      continue;
+    }
+
+    write_class(out, t, request_types, result_types, w);
+  }
+
+  for (std::size_t function = 0; function < functions_n; function++) {
+    tl_combinator *t = config.get_function_by_num(function);
+    if (!w.is_combinator_supported(t)) {
+      std::fprintf(stderr, "Function %s is too hard to store\n", t->name.c_str());
+      continue;
+    }
+
+    write_function(out, t, request_types, result_types, w);
+  }
+  out.append(w.gen_output_end());
+
+  for (std::size_t type = 0; type < types_n; type++) {
+    tl_type *t = config.get_type_by_num(type);
+    if (t->flags & FLAG_COMPLEX) {
+      t->flags &= ~FLAG_COMPLEX;  // remove temporary flag
+    }
+  }
+}
+
+tl_config read_tl_config_from_file(const std::string &file_name) {
+  std::string config = get_file_contents(file_name, "rb");
+  if (config.empty()) {
+    std::fprintf(stderr, "Config file %s is empty\n", file_name.c_str());
+    std::abort();
+  }
+  if (config.size() % sizeof(std::int32_t) != 0) {
+    std::fprintf(stderr, "Config size = %d is not multiple of %d\n", static_cast<int>(config.size()),
+                 static_cast<int>(sizeof(std::int32_t)));
+    std::abort();
+  }
+
+  tl_config_parser parser(config.c_str(), config.size());
+  return parser.parse_config();
+}
+
+bool write_tl_to_file(const tl_config &config, const std::string &file_name, const TL_writer &w) {
+  tl_string_outputer out;
+  write_tl(config, out, w);
+
+  auto old_file_contents = get_file_contents(file_name, "rb");
+  if (!w.is_documentation_generated()) {
+    old_file_contents = remove_documentation(old_file_contents);
+  }
+
+  if (old_file_contents != out.get_result()) {
+    std::fprintf(stderr, "Write tl to file %s\n", file_name.c_str());
+    return put_file_contents(file_name, "wb", out.get_result());
+  }
+
+  return true;
+}
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_generate.h b/libs/tdlib/td/tdtl/td/tl/tl_generate.h
new file mode 100644
index 0000000000..3523d1c828
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_generate.h
@@ -0,0 +1,24 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "tl_config.h"
+#include "tl_outputer.h"
+#include "tl_writer.h"
+
+#include <string>
+
+namespace td {
+namespace tl {
+
+void write_tl(const tl_config &config, tl_outputer &out, const TL_writer &w);
+
+tl_config read_tl_config_from_file(const std::string &file_name);
+bool write_tl_to_file(const tl_config &config, const std::string &file_name, const TL_writer &w);
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_outputer.cpp b/libs/tdlib/td/tdtl/td/tl/tl_outputer.cpp
new file mode 100644
index 0000000000..fed4ceb818
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_outputer.cpp
@@ -0,0 +1,16 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_outputer.h"
+
+namespace td {
+namespace tl {
+
+tl_outputer::~tl_outputer() {
+}
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_outputer.h b/libs/tdlib/td/tdtl/td/tl/tl_outputer.h
new file mode 100644
index 0000000000..47c0ab4fed
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_outputer.h
@@ -0,0 +1,22 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include <string>
+
+namespace td {
+namespace tl {
+
+class tl_outputer {
+ public:
+  virtual void append(const std::string &str) = 0;
+
+  virtual ~tl_outputer() = 0;
+};
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_simple.h b/libs/tdlib/td/tdtl/td/tl/tl_simple.h
new file mode 100644
index 0000000000..bf4801f1e2
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_simple.h
@@ -0,0 +1,204 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/tl/tl_config.h"
+
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <map>
+#include <memory>
+#include <string>
+#include <vector>
+
+namespace td {
+namespace tl {
+namespace simple {
+// TL type is
+
+std::string gen_cpp_name(std::string name) {
+  for (std::size_t i = 0; i < name.size(); i++) {
+    if ((name[i] < '0' || '9' < name[i]) && (name[i] < 'a' || 'z' < name[i]) && (name[i] < 'A' || 'Z' < name[i])) {
+      name[i] = '_';
+    }
+  }
+  assert(name.size() > 0);
+  assert(name[name.size() - 1] != '_');
+  return name;
+}
+
+std::string gen_cpp_field_name(std::string name) {
+  return gen_cpp_name(name) + "_";
+}
+
+struct CustomType;
+struct Type {
+  enum { Int32, Int53, Int64, Double, String, Bytes, Vector, Bool, Custom } type;
+
+  // type == Custom
+  bool is_bare{false};
+  const CustomType *custom{nullptr};
+
+  // type == Vector
+  const Type *vector_value_type{nullptr};
+};  // namespace simple
+
+struct Arg {
+  const Type *type;
+  std::string name;
+};
+
+struct Constructor {
+  std::string name;
+  std::int32_t id;
+  std::vector<Arg> args;
+  const CustomType *type;
+};
+
+struct CustomType {
+  std::string name;
+  std::vector<const Constructor *> constructors;
+};
+
+struct Function {
+  std::string name;
+  std::int32_t id;
+  std::vector<Arg> args;
+  const Type *type;
+};
+
+class Schema {
+ public:
+  explicit Schema(const tl_config &config) {
+    config_ = &config;
+    for (std::size_t type_num = 0, type_count = config.get_type_count(); type_num < type_count; type_num++) {
+      auto *from_type = config.get_type_by_num(type_num);
+      if (from_type->name == "Vector") {
+        continue;
+      }
+      auto *type = get_type(from_type);
+      if (type->type == Type::Custom) {
+        custom_types.push_back(type->custom);
+      }
+    }
+    for (std::size_t function_num = 0, function_count = config.get_function_count(); function_num < function_count;
+         function_num++) {
+      auto *from_function = config.get_function_by_num(function_num);
+      functions.push_back(get_function(from_function));
+    }
+  }
+
+  std::vector<const CustomType *> custom_types;
+  std::vector<const Function *> functions;
+
+ private:
+  std::vector<std::unique_ptr<Function>> functions_;
+  std::vector<std::unique_ptr<Constructor>> constructors_;
+  std::vector<std::unique_ptr<CustomType>> custom_types_;
+  std::vector<std::unique_ptr<Type>> types_;
+
+  const tl_config *config_{nullptr};
+  std::map<std::int32_t, Type *> type_by_id;
+  std::map<std::int32_t, Constructor *> constructor_by_id;
+  std::map<std::int32_t, Function *> function_by_id;
+
+  const Type *get_type(const tl_type *from_type) {
+    auto &type = type_by_id[from_type->id];
+    if (!type) {
+      types_.push_back(std::make_unique<Type>());
+      type = types_.back().get();
+
+      if (from_type->name == "Int32") {
+        type->type = Type::Int32;
+      } else if (from_type->name == "Int53") {
+        type->type = Type::Int53;
+      } else if (from_type->name == "Int64") {
+        type->type = Type::Int64;
+      } else if (from_type->name == "Double") {
+        type->type = Type::Double;
+      } else if (from_type->name == "String") {
+        type->type = Type::String;
+      } else if (from_type->name == "Bytes") {
+        type->type = Type::Bytes;
+      } else if (from_type->name == "Bool") {
+        type->type = Type::Bool;
+      } else if (from_type->name == "Vector") {
+        assert(false);  // unreachable
+      } else {
+        type->type = Type::Custom;
+        custom_types_.push_back(std::make_unique<CustomType>());
+        auto *custom_type = custom_types_.back().get();
+        type->custom = custom_type;
+        custom_type->name = from_type->name;
+        for (auto *constructor : from_type->constructors) {
+          custom_type->constructors.push_back(get_constructor(constructor));
+        }
+      }
+    }
+    return type;
+  }
+  const CustomType *get_custom_type(const tl_type *from_type) {
+    auto *type = get_type(from_type);
+    assert(type->type == Type::Custom);
+    return type->custom;
+  }
+
+  const Constructor *get_constructor(const tl_combinator *from) {
+    auto &constructor = constructor_by_id[from->id];
+    if (!constructor) {
+      constructors_.push_back(std::make_unique<Constructor>());
+      constructor = constructors_.back().get();
+      constructor->id = from->id;
+      constructor->name = from->name;
+      constructor->type = get_custom_type(config_->get_type(from->type_id));
+      for (auto &from_arg : from->args) {
+        Arg arg;
+        arg.name = from_arg.name;
+        arg.type = get_type(from_arg.type);
+        constructor->args.push_back(std::move(arg));
+      }
+    }
+    return constructor;
+  }
+  const Function *get_function(const tl_combinator *from) {
+    auto &function = function_by_id[from->id];
+    if (!function) {
+      functions_.push_back(std::make_unique<Function>());
+      function = functions_.back().get();
+      function->id = from->id;
+      function->name = from->name;
+      function->type = get_type(config_->get_type(from->type_id));
+      for (auto &from_arg : from->args) {
+        Arg arg;
+        arg.name = from_arg.name;
+        arg.type = get_type(from_arg.type);
+        function->args.push_back(std::move(arg));
+      }
+    }
+    return function;
+  }
+  const Type *get_type(const tl_tree *tree) {
+    assert(tree->get_type() == NODE_TYPE_TYPE);
+    auto *type_tree = static_cast<const tl_tree_type *>(tree);
+    if (type_tree->type->name == "Vector") {
+      assert(type_tree->children.size() == 1);
+      types_.push_back(std::make_unique<Type>());
+      auto *type = types_.back().get();
+      type->type = Type::Vector;
+      type->vector_value_type = get_type(type_tree->children[0]);
+      return type;
+    } else {
+      assert(type_tree->children.empty());
+      return get_type(type_tree->type);
+    }
+  }
+};
+
+}  // namespace simple
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_simple_parser.h b/libs/tdlib/td/tdtl/td/tl/tl_simple_parser.h
new file mode 100644
index 0000000000..9e612bf799
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_simple_parser.h
@@ -0,0 +1,107 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include <cassert>
+#include <cstdint>
+#include <cstring>
+#include <string>
+
+namespace td {
+namespace tl {
+
+class tl_simple_parser {
+  const char *data;
+  const char *data_begin;
+  std::size_t data_len;
+  const char *error;
+  std::size_t error_pos;
+
+  void set_error(const char *error_message) {
+    if (error == NULL) {
+      assert(error_message != NULL);
+      error = error_message;
+      error_pos = static_cast<std::size_t>(data - data_begin);
+      data = "\x00\x00\x00\x00\x00\x00\x00\x00";
+      data_len = 0;
+    } else {
+      data = "\x00\x00\x00\x00\x00\x00\x00\x00";
+      assert(data_len == 0);
+    }
+  }
+
+  void check_len(const std::size_t len) {
+    if (data_len < len) {
+      set_error("Not enough data to read");
+    } else {
+      data_len -= len;
+    }
+  }
+
+  tl_simple_parser(const tl_simple_parser &other);
+  tl_simple_parser &operator=(const tl_simple_parser &other);
+
+ public:
+  tl_simple_parser(const char *data, std::size_t data_len)
+      : data(data), data_begin(data), data_len(data_len), error(), error_pos() {
+  }
+
+  const char *get_error() const {
+    return error;
+  }
+
+  std::size_t get_error_pos() const {
+    return error_pos;
+  }
+
+  std::int32_t fetch_int() {
+    check_len(sizeof(std::int32_t));
+    std::int32_t result = *reinterpret_cast<const std::int32_t *>(data);
+    data += sizeof(std::int32_t);
+    return result;
+  }
+
+  std::int64_t fetch_long() {
+    check_len(sizeof(std::int64_t));
+    std::int64_t result;
+    std::memcpy(reinterpret_cast<char *>(&result), data, sizeof(std::int64_t));
+    data += sizeof(std::int64_t);
+    return result;
+  }
+
+  std::string fetch_string() {
+    check_len(4);
+    int result_len = static_cast<unsigned char>(data[0]);
+    if (result_len < 254) {
+      check_len((result_len >> 2) * 4);
+      std::string result(data + 1, result_len);
+      data += ((result_len >> 2) + 1) * 4;
+      return result;
+    }
+
+    if (result_len == 254) {
+      result_len = static_cast<unsigned char>(data[1]) + (static_cast<unsigned char>(data[2]) << 8) +
+                   (static_cast<unsigned char>(data[3]) << 16);
+      check_len(((result_len + 3) >> 2) * 4);
+      std::string result(data + 4, result_len);
+      data += ((result_len + 7) >> 2) * 4;
+      return result;
+    }
+
+    set_error("Can't fetch string, 255 found");
+    return std::string();
+  }
+
+  void fetch_end() {
+    if (data_len) {
+      set_error("Too much data to fetch");
+    }
+  }
+};
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_string_outputer.cpp b/libs/tdlib/td/tdtl/td/tl/tl_string_outputer.cpp
new file mode 100644
index 0000000000..4a72ecdccd
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_string_outputer.cpp
@@ -0,0 +1,21 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_string_outputer.h"
+
+namespace td {
+namespace tl {
+
+void tl_string_outputer::append(const std::string &str) {
+  result += str;
+}
+
+const std::string &tl_string_outputer::get_result() const {
+  return result;
+}
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_string_outputer.h b/libs/tdlib/td/tdtl/td/tl/tl_string_outputer.h
new file mode 100644
index 0000000000..f0936340da
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_string_outputer.h
@@ -0,0 +1,26 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "tl_outputer.h"
+
+#include <string>
+
+namespace td {
+namespace tl {
+
+class tl_string_outputer : public tl_outputer {
+  std::string result;
+
+ public:
+  virtual void append(const std::string &str);
+
+  const std::string &get_result() const;
+};
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_writer.cpp b/libs/tdlib/td/tdtl/td/tl/tl_writer.cpp
new file mode 100644
index 0000000000..f1d8b2e18a
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_writer.cpp
@@ -0,0 +1,231 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "tl_writer.h"
+
+#include "tl_core.h"
+
+#include <cassert>
+#include <cstdio>
+
+namespace td {
+namespace tl {
+
+std::string TL_writer::int_to_string(int x) {
+  char buf[15];
+  std::sprintf(buf, "%d", x);
+  return buf;
+}
+
+bool TL_writer::is_alnum(char c) {
+  return ('0' <= c && c <= '9') || ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z');
+}
+
+char TL_writer::to_lower(char c) {
+  return 'A' <= c && c <= 'Z' ? static_cast<char>(c - 'A' + 'a') : c;
+}
+
+char TL_writer::to_upper(char c) {
+  return 'a' <= c && c <= 'z' ? static_cast<char>(c - 'a' + 'A') : c;
+}
+
+std::vector<std::string> TL_writer::get_additional_functions() const {
+  return std::vector<std::string>();
+}
+
+bool TL_writer::is_type_supported(const tl_tree_type *tree_type) const {
+  if (tree_type->type->flags & FLAG_COMPLEX) {
+    return false;
+  }
+
+  for (std::size_t i = 0; i < tree_type->children.size(); i++) {
+    const tl_tree *child = tree_type->children[i];
+    assert(child->get_type() == NODE_TYPE_TYPE || child->get_type() == NODE_TYPE_VAR_TYPE ||
+           child->get_type() == NODE_TYPE_NAT_CONST || child->get_type() == NODE_TYPE_VAR_NUM);
+
+    if (child->get_type() == NODE_TYPE_TYPE) {
+      if (!is_type_supported(static_cast<const tl_tree_type *>(child))) {
+        return false;
+      }
+    }
+    if (child->get_type() == NODE_TYPE_VAR_TYPE) {
+      return false;  // TODO
+    }
+  }
+
+  return true;
+}
+
+bool TL_writer::is_combinator_supported(const tl_combinator *constructor) const {
+  std::vector<bool> is_function_result(constructor->var_count);
+  for (std::size_t i = 0; i < constructor->args.size(); i++) {
+    const arg &a = constructor->args[i];
+
+    int arg_type = a.type->get_type();
+    if (arg_type == NODE_TYPE_VAR_TYPE) {
+      const tl_tree_var_type *t = static_cast<const tl_tree_var_type *>(a.type);
+      if (a.flags & FLAG_EXCL) {
+        assert(t->var_num >= 0);
+        if (is_function_result[t->var_num]) {
+          return false;  // lazy to check that result of two function calls is the same
+        }
+        is_function_result[t->var_num] = true;
+      } else {
+        return false;  // do not support generic types
+      }
+    }
+  }
+
+  for (std::size_t i = 0; i < constructor->args.size(); i++) {
+    const arg &a = constructor->args[i];
+
+    int arg_type = a.type->get_type();
+    if (a.var_num >= 0) {
+      assert(arg_type == NODE_TYPE_TYPE);
+      const tl_tree_type *a_type = static_cast<const tl_tree_type *>(a.type);
+      if (a_type->type->id == ID_VAR_TYPE) {
+        assert(!(a_type->flags & FLAG_EXCL));
+        if (!is_function_result[a.var_num]) {
+          assert(false);  // not possible, otherwise type is an argument of a type, but all types with type arguments
+                          // are already marked complex
+          return false;
+        } else {
+          continue;
+        }
+      }
+    }
+
+    if (arg_type == NODE_TYPE_VAR_TYPE) {
+      continue;
+    } else if (arg_type == NODE_TYPE_TYPE) {
+      if (!is_type_supported(static_cast<const tl_tree_type *>(a.type))) {
+        return false;
+      }
+    } else {
+      assert(arg_type == NODE_TYPE_ARRAY);
+      const tl_tree_array *arr = static_cast<const tl_tree_array *>(a.type);
+      for (std::size_t j = 0; j < arr->args.size(); j++) {
+        const arg &b = arr->args[j];
+        assert(b.type->get_type() == NODE_TYPE_TYPE && b.var_num == -1);
+        if (!is_type_supported(static_cast<const tl_tree_type *>(b.type))) {
+          return false;
+        }
+      }
+    }
+  }
+
+  tl_tree *result = constructor->result;
+  if (result->get_type() == NODE_TYPE_TYPE) {
+    if (!is_type_supported(static_cast<const tl_tree_type *>(result))) {
+      return false;
+    }
+  } else {
+    assert(result->get_type() == NODE_TYPE_VAR_TYPE);
+    const tl_tree_var_type *t = static_cast<const tl_tree_var_type *>(result);
+    return is_function_result[t->var_num];
+  }
+
+  return true;
+}
+
+bool TL_writer::is_documentation_generated() const {
+  return false;
+}
+
+std::string TL_writer::gen_main_class_name(const tl_type *t) const {
+  if (t->simple_constructors == 1) {
+    for (std::size_t i = 0; i < t->constructors_num; i++) {
+      if (is_combinator_supported(t->constructors[i])) {
+        return gen_class_name(t->constructors[i]->name);
+      }
+    }
+  }
+
+  return gen_class_name(t->name);
+}
+
+int TL_writer::get_parser_type(const tl_combinator *t, const std::string &parser_name) const {
+  return t->var_count > 0;
+}
+
+int TL_writer::get_storer_type(const tl_combinator *t, const std::string &storer_name) const {
+  return 0;
+}
+
+int TL_writer::get_additional_function_type(const std::string &additional_function_name) const {
+  return 0;
+}
+
+TL_writer::Mode TL_writer::get_parser_mode(int type) const {
+  return All;
+}
+
+TL_writer::Mode TL_writer::get_storer_mode(int type) const {
+  return All;
+}
+
+std::string TL_writer::gen_field_type(const arg &a) const {
+  if (a.flags & FLAG_EXCL) {
+    assert(a.flags == FLAG_EXCL);
+    assert(a.type->get_type() == NODE_TYPE_VAR_TYPE);
+
+    return gen_var_type_name();
+  }
+
+  assert(a.flags == FLAG_NOVAR || a.flags == 0 || a.flags == (FLAG_OPT_VAR | FLAG_NOVAR | FLAG_BARE));
+
+  if (a.type->get_type() == NODE_TYPE_TYPE) {
+    const tl_tree_type *arg_type = static_cast<const tl_tree_type *>(a.type);
+    assert(arg_type->children.size() == static_cast<std::size_t>(arg_type->type->arity));
+
+    if (arg_type->type->id == ID_VAR_TYPE) {
+      return std::string();
+    }
+
+    return gen_type_name(arg_type);
+  } else {
+    assert(a.flags == FLAG_NOVAR || a.flags == 0);
+
+    assert(a.type->get_type() == NODE_TYPE_ARRAY);
+    const tl_tree_array *arg_array = static_cast<const tl_tree_array *>(a.type);
+    assert((arg_array->flags & ~FLAG_NOVAR) == 0);
+    return gen_array_type_name(arg_array, a.name);
+  }
+}
+
+std::string TL_writer::gen_additional_function(const std::string &function_name, const tl_combinator *t,
+                                               bool is_function) const {
+  assert(false);
+  return "";
+}
+
+std::string TL_writer::gen_additional_proxy_function_begin(const std::string &function_name, const tl_type *type,
+                                                           const std::string &class_name, int arity,
+                                                           bool is_function) const {
+  assert(false);
+  return "";
+}
+
+std::string TL_writer::gen_additional_proxy_function_case(const std::string &function_name, const tl_type *type,
+                                                          const std::string &class_name, int arity) const {
+  assert(false);
+  return "";
+}
+
+std::string TL_writer::gen_additional_proxy_function_case(const std::string &function_name, const tl_type *type,
+                                                          const tl_combinator *t, int arity, bool is_function) const {
+  assert(false);
+  return "";
+}
+
+std::string TL_writer::gen_additional_proxy_function_end(const std::string &function_name, const tl_type *type,
+                                                         bool is_function) const {
+  assert(false);
+  return "";
+}
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdtl/td/tl/tl_writer.h b/libs/tdlib/td/tdtl/td/tl/tl_writer.h
new file mode 100644
index 0000000000..3c3847516b
--- /dev/null
+++ b/libs/tdlib/td/tdtl/td/tl/tl_writer.h
@@ -0,0 +1,162 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "tl_core.h"
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+namespace td {
+namespace tl {
+
+class var_description {
+ public:
+  int index;
+  bool is_stored;
+  bool is_type;
+  int parameter_num;
+  int function_arg_num;
+
+  var_description() : index(-1), is_stored(false), is_type(false), parameter_num(-1), function_arg_num(-1) {
+  }
+};
+
+class TL_writer {
+  TL_writer(const TL_writer &other);
+  TL_writer &operator=(const TL_writer &other);
+
+ protected:
+  const std::string tl_name;
+
+ public:
+  enum Mode { All, Client, Server };
+
+  explicit TL_writer(const std::string &tl_name) : tl_name(tl_name) {
+  }
+
+  virtual ~TL_writer() {
+  }
+
+  virtual int get_max_arity() const = 0;
+
+  static std::string int_to_string(int x);
+  static bool is_alnum(char c);
+  static char to_lower(char c);
+  static char to_upper(char c);
+
+  virtual bool is_built_in_simple_type(const std::string &name) const = 0;
+  virtual bool is_built_in_complex_type(const std::string &name) const = 0;
+  virtual bool is_type_supported(const tl_tree_type *tree_type) const;
+  virtual bool is_type_bare(const tl_type *t) const = 0;
+  virtual bool is_combinator_supported(const tl_combinator *constructor) const;
+  virtual bool is_documentation_generated() const;
+
+  virtual int get_parser_type(const tl_combinator *t, const std::string &parser_name) const;
+  virtual int get_storer_type(const tl_combinator *t, const std::string &storer_name) const;
+  virtual int get_additional_function_type(const std::string &additional_function_name) const;
+  virtual Mode get_parser_mode(int type) const;
+  virtual Mode get_storer_mode(int type) const;
+  virtual std::vector<std::string> get_parsers() const = 0;
+  virtual std::vector<std::string> get_storers() const = 0;
+  virtual std::vector<std::string> get_additional_functions() const;
+
+  virtual std::string gen_base_tl_class_name() const = 0;
+  virtual std::string gen_base_type_class_name(int arity) const = 0;
+  virtual std::string gen_base_function_class_name() const = 0;
+  virtual std::string gen_class_name(std::string name) const = 0;
+  virtual std::string gen_field_name(std::string name) const = 0;
+  virtual std::string gen_var_name(const var_description &desc) const = 0;
+  virtual std::string gen_parameter_name(int index) const = 0;
+  virtual std::string gen_main_class_name(const tl_type *t) const;
+  virtual std::string gen_field_type(const arg &a) const;
+  virtual std::string gen_type_name(const tl_tree_type *tree_type) const = 0;
+  virtual std::string gen_array_type_name(const tl_tree_array *arr, const std::string &field_name) const = 0;
+  virtual std::string gen_var_type_name() const = 0;
+
+  virtual std::string gen_int_const(const tl_tree *tree_c, const std::vector<var_description> &vars) const = 0;
+
+  virtual std::string gen_output_begin() const = 0;
+  virtual std::string gen_output_end() const = 0;
+
+  virtual std::string gen_forward_class_declaration(const std::string &class_name, bool is_proxy) const = 0;
+
+  virtual std::string gen_class_begin(const std::string &class_name, const std::string &base_class_name,
+                                      bool is_proxy) const = 0;
+  virtual std::string gen_class_end() const = 0;
+
+  virtual std::string gen_class_alias(const std::string &class_name, const std::string &alias_name) const = 0;
+
+  virtual std::string gen_field_definition(const std::string &class_name, const std::string &type_name,
+                                           const std::string &field_name) const = 0;
+  virtual std::string gen_flags_definitions(const tl_combinator *t) const {
+    return "";
+  }
+
+  virtual std::string gen_vars(const tl_combinator *t, const tl_tree_type *result_type,
+                               std::vector<var_description> &vars) const = 0;
+  virtual std::string gen_function_vars(const tl_combinator *t, std::vector<var_description> &vars) const = 0;
+  virtual std::string gen_uni(const tl_tree_type *result_type, std::vector<var_description> &vars,
+                              bool check_negative) const = 0;
+  virtual std::string gen_constructor_id_store(std::int32_t id, int storer_type) const = 0;
+  virtual std::string gen_field_fetch(int field_num, const arg &a, std::vector<var_description> &vars, bool flat,
+                                      int parser_type) const = 0;
+  virtual std::string gen_field_store(const arg &a, std::vector<var_description> &vars, bool flat,
+                                      int storer_type) const = 0;
+  virtual std::string gen_type_fetch(const std::string &field_name, const tl_tree_type *tree_type,
+                                     const std::vector<var_description> &vars, int parser_type) const = 0;
+  virtual std::string gen_type_store(const std::string &field_name, const tl_tree_type *tree_type,
+                                     const std::vector<var_description> &vars, int storer_type) const = 0;
+  virtual std::string gen_var_type_fetch(const arg &a) const = 0;
+
+  virtual std::string gen_get_id(const std::string &class_name, std::int32_t id, bool is_proxy) const = 0;
+
+  virtual std::string gen_function_result_type(const tl_tree *result) const = 0;
+
+  virtual std::string gen_fetch_function_begin(const std::string &parser_name, const std::string &class_name, int arity,
+                                               std::vector<var_description> &vars, int parser_type) const = 0;
+  virtual std::string gen_fetch_function_end(int field_num, const std::vector<var_description> &vars,
+                                             int parser_type) const = 0;
+
+  virtual std::string gen_fetch_function_result_begin(const std::string &parser_name, const std::string &class_name,
+                                                      const tl_tree *result) const = 0;
+  virtual std::string gen_fetch_function_result_end() const = 0;
+  virtual std::string gen_fetch_function_result_any_begin(const std::string &parser_name, const std::string &class_name,
+                                                          bool is_proxy) const = 0;
+  virtual std::string gen_fetch_function_result_any_end(bool is_proxy) const = 0;
+
+  virtual std::string gen_store_function_begin(const std::string &storer_name, const std::string &class_name, int arity,
+                                               std::vector<var_description> &vars, int storer_type) const = 0;
+  virtual std::string gen_store_function_end(const std::vector<var_description> &vars, int storer_type) const = 0;
+
+  virtual std::string gen_fetch_switch_begin() const = 0;
+  virtual std::string gen_fetch_switch_case(const tl_combinator *t, int arity) const = 0;
+  virtual std::string gen_fetch_switch_end() const = 0;
+
+  virtual std::string gen_constructor_begin(int fields_num, const std::string &class_name, bool is_default) const = 0;
+  virtual std::string gen_constructor_parameter(int field_num, const std::string &class_name, const arg &a,
+                                                bool is_default) const = 0;
+  virtual std::string gen_constructor_field_init(int field_num, const std::string &class_name, const arg &a,
+                                                 bool is_default) const = 0;
+  virtual std::string gen_constructor_end(const tl_combinator *t, int fields_num, bool is_default) const = 0;
+
+  virtual std::string gen_additional_function(const std::string &function_name, const tl_combinator *t,
+                                              bool is_function) const;
+  virtual std::string gen_additional_proxy_function_begin(const std::string &function_name, const tl_type *type,
+                                                          const std::string &class_name, int arity,
+                                                          bool is_function) const;
+  virtual std::string gen_additional_proxy_function_case(const std::string &function_name, const tl_type *type,
+                                                         const std::string &class_name, int arity) const;
+  virtual std::string gen_additional_proxy_function_case(const std::string &function_name, const tl_type *type,
+                                                         const tl_combinator *t, int arity, bool is_function) const;
+  virtual std::string gen_additional_proxy_function_end(const std::string &function_name, const tl_type *type,
+                                                        bool is_function) const;
+};
+
+}  // namespace tl
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/CMakeLists.txt b/libs/tdlib/td/tdutils/CMakeLists.txt
new file mode 100644
index 0000000000..1fbc34df32
--- /dev/null
+++ b/libs/tdlib/td/tdutils/CMakeLists.txt
@@ -0,0 +1,244 @@
+cmake_minimum_required(VERSION 3.0.2 FATAL_ERROR)
+
+if (NOT ZLIB_FOUND)
+  find_package(ZLIB)
+endif()
+if (ZLIB_FOUND)
+  set(TD_HAVE_ZLIB 1)
+  message(STATUS "Found ZLIB: ${ZLIB_INCLUDE_DIR} ${ZLIB_LIBRARIES}")
+
+  # OpenSSL internally depends on zlib
+  if (NOT OPENSSL_FOUND)
+    find_package(OpenSSL)
+  endif()
+  if (OPENSSL_FOUND)
+    set(TD_HAVE_OPENSSL 1)
+  endif()
+endif()
+
+configure_file(td/utils/config.h.in td/utils/config.h @ONLY)
+
+add_subdirectory(generate)
+
+# TDUTILS
+set_source_files_properties(${TDMIME_AUTO} PROPERTIES GENERATED TRUE)
+if (CLANG OR GCC)
+  set_property(SOURCE ${TDMIME_AUTO} APPEND_STRING PROPERTY COMPILE_FLAGS " -Wno-conversion")
+elseif (MSVC)
+  set_property(SOURCE ${TDMIME_AUTO} APPEND_STRING PROPERTY COMPILE_FLAGS " /wd4267")
+endif()
+if (CLANG)
+  set_property(SOURCE ${TDMIME_AUTO} APPEND_STRING PROPERTY COMPILE_FLAGS " -Wno-deprecated-register")
+endif()
+
+set(TDUTILS_SOURCE
+  td/utils/port/Clocks.cpp
+  td/utils/port/Fd.cpp
+  td/utils/port/FileFd.cpp
+  td/utils/port/IPAddress.cpp
+  td/utils/port/path.cpp
+  td/utils/port/ServerSocketFd.cpp
+  td/utils/port/signals.cpp
+  td/utils/port/sleep.cpp
+  td/utils/port/SocketFd.cpp
+  td/utils/port/Stat.cpp
+  td/utils/port/thread_local.cpp
+  td/utils/port/wstring_convert.cpp
+
+  td/utils/port/detail/Epoll.cpp
+  td/utils/port/detail/EventFdBsd.cpp
+  td/utils/port/detail/EventFdLinux.cpp
+  td/utils/port/detail/EventFdWindows.cpp
+  td/utils/port/detail/KQueue.cpp
+  td/utils/port/detail/Poll.cpp
+  td/utils/port/detail/Select.cpp
+  td/utils/port/detail/ThreadIdGuard.cpp
+  td/utils/port/detail/WineventPoll.cpp
+
+  ${TDMIME_AUTO}
+
+  td/utils/base64.cpp
+  td/utils/BigNum.cpp
+  td/utils/buffer.cpp
+  td/utils/crypto.cpp
+  td/utils/FileLog.cpp
+  td/utils/filesystem.cpp
+  td/utils/find_boundary.cpp
+  td/utils/Gzip.cpp
+  td/utils/GzipByteFlow.cpp
+  td/utils/Hints.cpp
+  td/utils/HttpUrl.cpp
+  td/utils/JsonBuilder.cpp
+  td/utils/logging.cpp
+  td/utils/misc.cpp
+  td/utils/MimeType.cpp
+  td/utils/Random.cpp
+  td/utils/StackAllocator.cpp
+  td/utils/Status.cpp
+  td/utils/StringBuilder.cpp
+  td/utils/Time.cpp
+  td/utils/Timer.cpp
+  td/utils/tl_parsers.cpp
+  td/utils/unicode.cpp
+  td/utils/utf8.cpp
+
+  td/utils/port/Clocks.h
+  td/utils/port/config.h
+  td/utils/port/CxCli.h
+  td/utils/port/EventFd.h
+  td/utils/port/EventFdBase.h
+  td/utils/port/Fd.h
+  td/utils/port/FileFd.h
+  td/utils/port/IPAddress.h
+  td/utils/port/path.h
+  td/utils/port/platform.h
+  td/utils/port/Poll.h
+  td/utils/port/PollBase.h
+  td/utils/port/RwMutex.h
+  td/utils/port/ServerSocketFd.h
+  td/utils/port/signals.h
+  td/utils/port/sleep.h
+  td/utils/port/SocketFd.h
+  td/utils/port/Stat.h
+  td/utils/port/thread.h
+  td/utils/port/thread_local.h
+  td/utils/port/wstring_convert.h
+
+  td/utils/port/detail/Epoll.h
+  td/utils/port/detail/EventFdBsd.h
+  td/utils/port/detail/EventFdLinux.h
+  td/utils/port/detail/EventFdWindows.h
+  td/utils/port/detail/KQueue.h
+  td/utils/port/detail/Poll.h
+  td/utils/port/detail/Select.h
+  td/utils/port/detail/ThreadIdGuard.h
+  td/utils/port/detail/ThreadPthread.h
+  td/utils/port/detail/ThreadStl.h
+  td/utils/port/detail/WineventPoll.h
+
+  td/utils/AesCtrByteFlow.h
+  td/utils/base64.h
+  td/utils/benchmark.h
+  td/utils/BigNum.h
+  td/utils/buffer.h
+  td/utils/BufferedFd.h
+  td/utils/BufferedReader.h
+  td/utils/ByteFlow.h
+  td/utils/ChangesProcessor.h
+  td/utils/Closure.h
+  td/utils/common.h
+  td/utils/Container.h
+  td/utils/crypto.h
+  td/utils/Enumerator.h
+  td/utils/FileLog.h
+  td/utils/filesystem.h
+  td/utils/find_boundary.h
+  td/utils/FloodControlFast.h
+  td/utils/FloodControlStrict.h
+  td/utils/format.h
+  td/utils/Gzip.h
+  td/utils/GzipByteFlow.h
+  td/utils/HazardPointers.h
+  td/utils/Heap.h
+  td/utils/Hints.h
+  td/utils/HttpUrl.h
+  td/utils/int_types.h
+  td/utils/invoke.h
+  td/utils/JsonBuilder.h
+  td/utils/List.h
+  td/utils/logging.h
+  td/utils/MemoryLog.h
+  td/utils/MimeType.h
+  td/utils/misc.h
+  td/utils/MovableValue.h
+  td/utils/MpmcQueue.h
+  td/utils/MpmcWaiter.h
+  td/utils/MpscPollableQueue.h
+  td/utils/MpscLinkQueue.h
+  td/utils/Named.h
+  td/utils/ObjectPool.h
+  td/utils/Observer.h
+  td/utils/optional.h
+  td/utils/OptionsParser.h
+  td/utils/OrderedEventsProcessor.h
+  td/utils/overloaded.h
+  td/utils/Parser.h
+  td/utils/PathView.h
+  td/utils/queue.h
+  td/utils/Random.h
+  td/utils/ScopeGuard.h
+  td/utils/SharedObjectPool.h
+  td/utils/Slice-decl.h
+  td/utils/Slice.h
+  td/utils/SpinLock.h
+  td/utils/StackAllocator.h
+  td/utils/Status.h
+  td/utils/Storer.h
+  td/utils/StorerBase.h
+  td/utils/StringBuilder.h
+  td/utils/tests.h
+  td/utils/Time.h
+  td/utils/TimedStat.h
+  td/utils/Timer.h
+  td/utils/tl_helpers.h
+  td/utils/tl_parsers.h
+  td/utils/tl_storers.h
+  td/utils/type_traits.h
+  td/utils/unicode.h
+  td/utils/utf8.h
+  td/utils/Variant.h
+)
+
+set(TDUTILS_TEST_SOURCE
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/crypto.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/Enumerator.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/filesystem.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/gzip.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/HazardPointers.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/heap.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/json.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/misc.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/MpmcQueue.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/MpmcWaiter.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/MpscLinkQueue.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/OrderedEventsProcessor.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/pq.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/SharedObjectPool.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/test/variant.cpp
+  PARENT_SCOPE
+)
+
+#RULES
+#LIBRARIES
+add_library(tdutils STATIC ${TDUTILS_SOURCE})
+if (WIN32)
+  # find_library(WS2_32_LIBRARY ws2_32)
+  # find_library(MSWSOCK_LIBRARY Mswsock)
+  # target_link_libraries(tdutils PRIVATE ${WS2_32_LIBRARY} ${MSWSOCK_LIBRARY})
+  target_link_libraries(tdutils PRIVATE ws2_32 Mswsock)
+endif()
+if (NOT CMAKE_CROSSCOMPILING)
+  add_dependencies(tdutils tdmime_auto)
+endif()
+
+if (DEFINED CMAKE_THREAD_LIBS_INIT)
+  target_link_libraries(tdutils PUBLIC ${CMAKE_THREAD_LIBS_INIT})
+endif()
+target_include_directories(tdutils PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}> $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}>)
+
+if (OPENSSL_FOUND)
+  target_link_libraries(tdutils PRIVATE ${OPENSSL_CRYPTO_LIBRARY} ${CMAKE_DL_LIBS} ${ZLIB_LIBRARIES})
+  target_include_directories(tdutils SYSTEM PRIVATE ${OPENSSL_INCLUDE_DIR})
+endif()
+
+if (ZLIB_FOUND)
+  target_link_libraries(tdutils PRIVATE ${ZLIB_LIBRARIES})
+  target_include_directories(tdutils SYSTEM PRIVATE ${ZLIB_INCLUDE_DIR})
+endif()
+
+install(TARGETS tdutils EXPORT TdTargets
+  LIBRARY DESTINATION lib
+  ARCHIVE DESTINATION lib
+  RUNTIME DESTINATION bin
+  INCLUDES DESTINATION include
+)
diff --git a/libs/tdlib/td/tdutils/generate/CMakeLists.txt b/libs/tdlib/td/tdutils/generate/CMakeLists.txt
new file mode 100644
index 0000000000..69697b04b8
--- /dev/null
+++ b/libs/tdlib/td/tdutils/generate/CMakeLists.txt
@@ -0,0 +1,64 @@
+cmake_minimum_required(VERSION 3.0.2 FATAL_ERROR)
+
+# Generates files for MIME type <-> extension conversions
+# DEPENDS ON: gperf grep bash/powershell
+
+file(MAKE_DIRECTORY auto)
+
+set(TDMIME_SOURCE
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/mime_type_to_extension.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/auto/extension_to_mime_type.cpp
+)
+set(TDMIME_AUTO
+  ${TDMIME_SOURCE}
+  PARENT_SCOPE
+)
+
+add_custom_target(tdmime_auto DEPENDS ${TDMIME_SOURCE})
+
+if (NOT CMAKE_CROSSCOMPILING)
+  find_program(GPERF_EXECUTABLE gperf)
+  if (NOT GPERF_EXECUTABLE)
+    message(FATAL_ERROR "Could NOT find gperf. Path to gperf needs to be specified manually, i.e. 'cmake -DGPERF_EXECUTABLE:FILEPATH=\"<path to gperf executable>\" .')")
+  endif()
+
+  set(GPERF_FILES
+    ${CMAKE_CURRENT_SOURCE_DIR}/auto/mime_type_to_extension.gperf
+    ${CMAKE_CURRENT_SOURCE_DIR}/auto/extension_to_mime_type.gperf
+  )
+
+  set(GPERF_GEN_SOURCE generate_mime_types_gperf.cpp)
+
+  add_executable(generate_mime_types_gperf ${GPERF_GEN_SOURCE})
+
+  add_custom_command(
+    OUTPUT ${GPERF_FILES}
+    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+    COMMAND generate_mime_types_gperf mime_types.txt ${GPERF_FILES}
+    DEPENDS generate_mime_types_gperf mime_types.txt
+  )
+
+  if (WIN32)
+    set(MIME_TYPE_TO_EXTENSION_CMD ${GPERF_EXECUTABLE} -m100 --output-file=auto/mime_type_to_extension.cpp auto/mime_type_to_extension.gperf)
+  else()
+    set(MIME_TYPE_TO_EXTENSION_CMD ${GPERF_EXECUTABLE} -m100 auto/mime_type_to_extension.gperf | grep -v __gnu_inline__ > auto/mime_type_to_extension.cpp)
+  endif()
+  add_custom_command(
+    OUTPUT ${CMAKE_CURRENT_SOURCE_DIR}/auto/mime_type_to_extension.cpp
+    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+    COMMAND ${MIME_TYPE_TO_EXTENSION_CMD}
+    DEPENDS auto/mime_type_to_extension.gperf
+  )
+
+  if (WIN32)
+    set(EXTENSION_TO_MIME_TYPE_CMD ${GPERF_EXECUTABLE} -m100 --output-file=auto/extension_to_mime_type.cpp auto/extension_to_mime_type.gperf)
+  else()
+    set(EXTENSION_TO_MIME_TYPE_CMD ${GPERF_EXECUTABLE} -m100 auto/extension_to_mime_type.gperf | grep -v __gnu_inline__ > auto/extension_to_mime_type.cpp)
+  endif()
+  add_custom_command(
+    OUTPUT ${CMAKE_CURRENT_SOURCE_DIR}/auto/extension_to_mime_type.cpp
+    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+    COMMAND ${EXTENSION_TO_MIME_TYPE_CMD}
+    DEPENDS auto/extension_to_mime_type.gperf
+  )
+endif()
diff --git a/libs/tdlib/td/tdutils/generate/generate_mime_types_gperf.cpp b/libs/tdlib/td/tdutils/generate/generate_mime_types_gperf.cpp
new file mode 100644
index 0000000000..ac7ff68605
--- /dev/null
+++ b/libs/tdlib/td/tdutils/generate/generate_mime_types_gperf.cpp
@@ -0,0 +1,146 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <string>
+#include <tuple>
+#include <utility>
+#include <vector>
+
+std::pair<std::string, std::string> split(std::string s, char delimiter = ' ') {
+  auto delimiter_pos = s.find(delimiter);
+  if (delimiter_pos == std::string::npos) {
+    return {std::move(s), ""};
+  } else {
+    auto head = s.substr(0, delimiter_pos);
+    auto tail = s.substr(delimiter_pos + 1);
+    return {head, tail};
+  }
+}
+
+bool generate(const char *file_name, const char *from_name, const char *to_name,
+              const std::map<std::string, std::string> &map) {
+  // binary mode is needed for MSYS2 gperf
+  std::ofstream out(file_name, std::ios_base::trunc | std::ios_base::binary);
+  if (!out) {
+    std::cerr << "Can't open output file \"" << file_name << std::endl;
+    return false;
+  }
+
+  out << "%struct-type\n";
+  out << "%ignore-case\n";
+  out << "%language=ANSI-C\n";
+  out << "%readonly-tables\n";
+  out << "%includes\n";
+  out << "%enum\n";
+  out << "%define slot-name " << from_name << "\n";
+  out << "%define initializer-suffix ,nullptr\n";
+  out << "%define slot-name " << from_name << "\n";
+  out << "%define hash-function-name " << from_name << "_hash\n";
+  out << "%define lookup-function-name search_" << from_name << "\n";
+  //  out << "%define class-name " << from_name << "_to_" << to_name << "\n";
+  out << "struct " << from_name << "_and_" << to_name << " {\n";
+  out << "  const char *" << from_name << ";\n";
+  out << "  const char *" << to_name << ";\n";
+  out << "}\n";
+  out << "%%\n";
+
+  for (auto &value : map) {
+    out << '"' << value.first << "\", \"" << value.second << '"' << "\n";
+  }
+
+  out << "%%\n";
+  out << "const char *" << from_name << "_to_" << to_name << "(const char *" << from_name << ", size_t " << from_name
+      << "_len) {\n";
+  out << "  const auto &result = search_" << from_name << "(" << from_name << ", " << from_name << "_len);\n";
+  out << "  if (result == nullptr) {\n";
+  out << "    return nullptr;\n";
+  out << "  }\n";
+  out << "\n";
+  out << "  return result->" << to_name << ";\n";
+  out << "}\n";
+
+  return true;
+}
+
+int main(int argc, char *argv[]) {
+  if (argc != 4) {
+    std::cerr << "Wrong number of arguments supplied. Expected 'generate_mime_types_gperf <mime_types.txt> "
+                 "<mime_type_to_extension.cpp> <extension_to_mime_type.cpp>'"
+              << std::endl;
+    return EXIT_FAILURE;
+  }
+
+  std::ifstream mime_types_file(argv[1]);
+  if (!mime_types_file) {
+    std::cerr << "Can't open input file \"" << argv[1] << std::endl;
+    return EXIT_FAILURE;
+  }
+
+  std::map<std::string, std::string> mime_type_to_extension;
+  std::map<std::string, std::string> extension_to_mime_type;
+
+  std::string line;
+  while (std::getline(mime_types_file, line)) {
+    while (!line.empty() && (line.back() == '\r' || line.back() == '\n')) {
+      line.pop_back();
+    }
+
+    std::string mime_type;
+    std::string extensions_string;
+    std::tie(mime_type, extensions_string) = split(line, '\t');
+
+    if (mime_type.empty()) {
+      std::cerr << "Wrong MIME type description \"" << line << "\"" << std::endl;
+      continue;
+    }
+
+    auto extensions_start_position = extensions_string.find_first_not_of(" \t");
+    if (extensions_start_position == std::string::npos) {
+      std::cerr << "Wrong MIME type description \"" << line << "\"" << std::endl;
+      continue;
+    }
+    extensions_string = extensions_string.substr(extensions_start_position);
+
+    std::vector<std::string> extensions;
+    while (!extensions_string.empty()) {
+      extensions.push_back("");
+      std::tie(extensions.back(), extensions_string) = split(extensions_string);
+    }
+    assert(!extensions.empty());
+
+    std::map<std::string, std::string> preffered_extensions{{"image/jpeg", "jpg"},  {"audio/mpeg", "mp3"},
+                                                            {"audio/midi", "midi"}, {"text/x-pascal", "pas"},
+                                                            {"text/x-asm", "asm"},  {"video/quicktime", "mov"}};
+    std::size_t index = 0;
+    if (preffered_extensions.count(mime_type) != 0) {
+      index = std::find(extensions.begin(), extensions.end(), preffered_extensions[mime_type]) - extensions.begin();
+      assert(index < extensions.size());
+    }
+    if (mime_type_to_extension.emplace_hint(mime_type_to_extension.end(), mime_type, extensions[index])->second !=
+        extensions[index]) {
+      std::cerr << "MIME type \"" << mime_type << "\" has more than one extensions list" << std::endl;
+    }
+
+    for (auto &extension : extensions) {
+      if (!extension_to_mime_type.emplace(extension, mime_type).second) {
+        std::cerr << "Extension \"" << extension << "\" matches more than one type" << std::endl;
+      }
+    }
+  }
+
+  if (!generate(argv[2], "mime_type", "extension", mime_type_to_extension)) {
+    return EXIT_FAILURE;
+  }
+  if (!generate(argv[3], "extension", "mime_type", extension_to_mime_type)) {
+    return EXIT_FAILURE;
+  }
+}
diff --git a/libs/tdlib/td/tdutils/generate/mime_types.txt b/libs/tdlib/td/tdutils/generate/mime_types.txt
new file mode 100644
index 0000000000..a2d4abbf29
--- /dev/null
+++ b/libs/tdlib/td/tdutils/generate/mime_types.txt
@@ -0,0 +1,765 @@
+application/andrew-inset			ez
+application/applixware				aw
+application/atom+xml				atom
+application/atomcat+xml				atomcat
+application/atomsvc+xml				atomsvc
+application/ccxml+xml				ccxml
+application/cdmi-capability			cdmia
+application/cdmi-container			cdmic
+application/cdmi-domain				cdmid
+application/cdmi-object				cdmio
+application/cdmi-queue				cdmiq
+application/cu-seeme				cu
+application/davmount+xml			davmount
+application/docbook+xml				dbk
+application/dssc+der				dssc
+application/dssc+xml				xdssc
+application/ecmascript				ecma
+application/emma+xml				emma
+application/epub+zip				epub
+application/exi					exi
+application/font-tdpfr				pfr
+application/gml+xml				gml
+application/gpx+xml				gpx
+application/gxf					gxf
+application/hyperstudio				stk
+application/inkml+xml				ink inkml
+application/ipfix				ipfix
+application/java-archive			jar
+application/java-serialized-object		ser
+application/java-vm				class
+application/javascript				js
+application/json				json
+application/jsonml+json				jsonml
+application/lost+xml				lostxml
+application/mac-binhex40			hqx
+application/mac-compactpro			cpt
+application/mads+xml				mads
+application/marc				mrc
+application/marcxml+xml				mrcx
+application/mathematica				ma nb mb
+application/mathml+xml				mathml
+application/mbox				mbox
+application/mediaservercontrol+xml		mscml
+application/metalink+xml			metalink
+application/metalink4+xml			meta4
+application/mets+xml				mets
+application/mods+xml				mods
+application/mp21				m21 mp21
+application/mp4					mp4s
+application/msword				doc dot
+application/mxf					mxf
+application/octet-stream	bin dms lrf mar so dist distz pkg bpk dump elc deploy
+application/oda					oda
+application/oebps-package+xml			opf
+application/ogg					ogx
+application/omdoc+xml				omdoc
+application/onenote				onetoc onetoc2 onetmp onepkg
+application/oxps				oxps
+application/patch-ops-error+xml			xer
+application/pdf					pdf
+application/pgp-encrypted			pgp
+application/pgp-signature			asc sig
+application/pics-rules				prf
+application/pkcs10				p10
+application/pkcs7-mime				p7m p7c
+application/pkcs7-signature			p7s
+application/pkcs8				p8
+application/pkix-attr-cert			ac
+application/pkix-cert				cer
+application/pkix-crl				crl
+application/pkix-pkipath			pkipath
+application/pkixcmp				pki
+application/pls+xml				pls
+application/postscript				ai eps ps
+application/prs.cww				cww
+application/pskc+xml				pskcxml
+application/rdf+xml				rdf
+application/reginfo+xml				rif
+application/relax-ng-compact-syntax		rnc
+application/resource-lists+xml			rl
+application/resource-lists-diff+xml		rld
+application/rls-services+xml			rs
+application/rpki-ghostbusters			gbr
+application/rpki-manifest			mft
+application/rpki-roa				roa
+application/rsd+xml				rsd
+application/rss+xml				rss
+application/rtf					rtf
+application/sbml+xml				sbml
+application/scvp-cv-request			scq
+application/scvp-cv-response			scs
+application/scvp-vp-request			spq
+application/scvp-vp-response			spp
+application/sdp					sdp
+application/set-payment-initiation		setpay
+application/set-registration-initiation		setreg
+application/shf+xml				shf
+application/smil+xml				smi smil
+application/sparql-query			rq
+application/sparql-results+xml			srx
+application/srgs				gram
+application/srgs+xml				grxml
+application/sru+xml				sru
+application/ssdl+xml				ssdl
+application/ssml+xml				ssml
+application/tei+xml				tei teicorpus
+application/thraud+xml				tfi
+application/timestamped-data			tsd
+application/vnd.3gpp.pic-bw-large		plb
+application/vnd.3gpp.pic-bw-small		psb
+application/vnd.3gpp.pic-bw-var			pvb
+application/vnd.3gpp2.tcap			tcap
+application/vnd.3m.post-it-notes		pwn
+application/vnd.accpac.simply.aso		aso
+application/vnd.accpac.simply.imp		imp
+application/vnd.acucobol			acu
+application/vnd.acucorp				atc acutc
+application/vnd.adobe.air-application-installer-package+zip	air
+application/vnd.adobe.formscentral.fcdt		fcdt
+application/vnd.adobe.fxp			fxp fxpl
+application/vnd.adobe.xdp+xml			xdp
+application/vnd.adobe.xfdf			xfdf
+application/vnd.ahead.space			ahead
+application/vnd.airzip.filesecure.azf		azf
+application/vnd.airzip.filesecure.azs		azs
+application/vnd.amazon.ebook			azw
+application/vnd.americandynamics.acc		acc
+application/vnd.amiga.ami			ami
+application/vnd.android.package-archive		apk
+application/vnd.anser-web-certificate-issue-initiation	cii
+application/vnd.anser-web-funds-transfer-initiation	fti
+application/vnd.antix.game-component		atx
+application/vnd.apple.installer+xml		mpkg
+application/vnd.apple.mpegurl			m3u8
+application/vnd.aristanetworks.swi		swi
+application/vnd.astraea-software.iota		iota
+application/vnd.audiograph			aep
+application/vnd.blueice.multipass		mpm
+application/vnd.bmi				bmi
+application/vnd.businessobjects			rep
+application/vnd.chemdraw+xml			cdxml
+application/vnd.chipnuts.karaoke-mmd		mmd
+application/vnd.cinderella			cdy
+application/vnd.claymore			cla
+application/vnd.cloanto.rp9			rp9
+application/vnd.clonk.c4group			c4g c4d c4f c4p c4u
+application/vnd.cluetrust.cartomobile-config		c11amc
+application/vnd.cluetrust.cartomobile-config-pkg	c11amz
+application/vnd.commonspace			csp
+application/vnd.contact.cmsg			cdbcmsg
+application/vnd.cosmocaller			cmc
+application/vnd.crick.clicker			clkx
+application/vnd.crick.clicker.keyboard		clkk
+application/vnd.crick.clicker.palette		clkp
+application/vnd.crick.clicker.template		clkt
+application/vnd.crick.clicker.wordbank		clkw
+application/vnd.criticaltools.wbs+xml		wbs
+application/vnd.ctc-posml			pml
+application/vnd.cups-ppd			ppd
+application/vnd.curl.car			car
+application/vnd.curl.pcurl			pcurl
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+message/rfc822					eml mime
+model/iges					igs iges
+model/mesh					msh mesh silo
+model/vnd.collada+xml				dae
+model/vnd.dwf					dwf
+model/vnd.gdl					gdl
+model/vnd.gtw					gtw
+model/vnd.mts					mts
+model/vnd.vtu					vtu
+model/vrml					wrl vrml
+model/x3d+binary				x3db x3dbz
+model/x3d+vrml					x3dv x3dvz
+model/x3d+xml					x3d x3dz
+text/cache-manifest				appcache
+text/calendar					ics ifb
+text/css					css
+text/csv					csv
+text/html					html htm
+text/n3						n3
+text/plain					txt text conf def list log in
+text/prs.lines.tag				dsc
+text/richtext					rtx
+text/sgml					sgml sgm
+text/tab-separated-values			tsv
+text/troff					t tr roff man me ms
+text/turtle					ttl
+text/uri-list					uri uris urls
+text/vcard					vcard
+text/vnd.curl					curl
+text/vnd.curl.dcurl				dcurl
+text/vnd.curl.scurl				scurl
+text/vnd.curl.mcurl				mcurl
+text/vnd.dvb.subtitle				sub
+text/vnd.fly					fly
+text/vnd.fmi.flexstor				flx
+text/vnd.graphviz				gv
+text/vnd.in3d.3dml				3dml
+text/vnd.in3d.spot				spot
+text/vnd.sun.j2me.app-descriptor		jad
+text/vnd.wap.wml				wml
+text/vnd.wap.wmlscript				wmls
+text/x-asm					s asm
+text/x-c					c cc cxx cpp h hh dic
+text/x-fortran					f for f77 f90
+text/x-java-source				java
+text/x-opml					opml
+text/x-pascal					p pas
+text/x-nfo					nfo
+text/x-setext					etx
+text/x-sfv					sfv
+text/x-uuencode					uu
+text/x-vcalendar				vcs
+text/x-vcard					vcf
+video/3gpp					3gp
+video/3gpp2					3g2
+video/h261					h261
+video/h263					h263
+video/h264					h264
+video/jpeg					jpgv
+video/jpm					jpm jpgm
+video/mj2					mj2 mjp2
+video/mp4					mp4 mp4v mpg4
+video/mpeg					mpeg mpg mpe m1v m2v
+video/ogg					ogv
+video/quicktime					qt mov
+video/vnd.dece.hd				uvh uvvh
+video/vnd.dece.mobile				uvm uvvm
+video/vnd.dece.pd				uvp uvvp
+video/vnd.dece.sd				uvs uvvs
+video/vnd.dece.video				uvv uvvv
+video/vnd.dvb.file				dvb
+video/vnd.fvt					fvt
+video/vnd.mpegurl				mxu m4u
+video/vnd.ms-playready.media.pyv		pyv
+video/vnd.uvvu.mp4				uvu uvvu
+video/vnd.vivo					viv
+video/webm					webm
+video/x-f4v					f4v
+video/x-fli					fli
+video/x-flv					flv
+video/x-m4v					m4v
+video/x-matroska				mkv mk3d mks
+video/x-mng					mng
+video/x-ms-asf					asf asx
+video/x-ms-vob					vob
+video/x-ms-wm					wm
+video/x-ms-wmv					wmv
+video/x-ms-wmx					wmx
+video/x-ms-wvx					wvx
+video/x-msvideo					avi
+video/x-sgi-movie				movie
+video/x-smv					smv
+x-conference/x-cooltalk				ice
diff --git a/libs/tdlib/td/tdutils/td/utils/AesCtrByteFlow.h b/libs/tdlib/td/tdutils/td/utils/AesCtrByteFlow.h
new file mode 100644
index 0000000000..820aa02fbe
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/AesCtrByteFlow.h
@@ -0,0 +1,55 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/ByteFlow.h"
+#include "td/utils/common.h"
+#include "td/utils/crypto.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+#if TD_HAVE_OPENSSL
+class AesCtrByteFlow : public ByteFlowInplaceBase {
+ public:
+  void init(const UInt256 &key, const UInt128 &iv) {
+    state_.init(key, iv);
+  }
+  void init(AesCtrState &&state) {
+    state_ = std::move(state);
+  }
+  AesCtrState move_aes_ctr_state() {
+    return std::move(state_);
+  }
+  void loop() override {
+    bool was_updated = false;
+    while (true) {
+      auto ready = input_->prepare_read();
+      if (ready.empty()) {
+        break;
+      }
+      state_.encrypt(ready, MutableSlice(const_cast<char *>(ready.data()), ready.size()));
+      input_->confirm_read(ready.size());
+      output_.advance_end(ready.size());
+      was_updated = true;
+    }
+    if (was_updated) {
+      on_output_updated();
+    }
+    if (!is_input_active_) {
+      finish(Status::OK());  // End of input stream.
+    }
+    set_need_size(1);
+  }
+
+ private:
+  AesCtrState state_;
+};
+#endif
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/BigNum.cpp b/libs/tdlib/td/tdutils/td/utils/BigNum.cpp
new file mode 100644
index 0000000000..f553661d49
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/BigNum.cpp
@@ -0,0 +1,251 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/BigNum.h"
+
+char disable_linker_warning_about_empty_file_bignum_cpp TD_UNUSED;
+
+#if TD_HAVE_OPENSSL
+
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+
+#include <openssl/bn.h>
+#include <openssl/crypto.h>
+
+namespace td {
+
+class BigNumContext::Impl {
+ public:
+  BN_CTX *big_num_context;
+
+  Impl() : big_num_context(BN_CTX_new()) {
+    LOG_IF(FATAL, big_num_context == nullptr);
+  }
+  Impl(const Impl &other) = delete;
+  Impl &operator=(const Impl &other) = delete;
+  Impl(Impl &&other) = delete;
+  Impl &operator=(Impl &&other) = delete;
+  ~Impl() {
+    BN_CTX_free(big_num_context);
+  }
+};
+
+BigNumContext::BigNumContext() : impl_(make_unique<Impl>()) {
+}
+
+BigNumContext::BigNumContext(BigNumContext &&other) = default;
+BigNumContext &BigNumContext::operator=(BigNumContext &&other) = default;
+
+BigNumContext::~BigNumContext() = default;
+
+class BigNum::Impl {
+ public:
+  BIGNUM *big_num;
+
+  Impl() : Impl(BN_new()) {
+  }
+  explicit Impl(BIGNUM *big_num) : big_num(big_num) {
+    LOG_IF(FATAL, big_num == nullptr);
+  }
+  Impl(const Impl &other) = delete;
+  Impl &operator=(const Impl &other) = delete;
+  Impl(Impl &&other) = delete;
+  Impl &operator=(Impl &&other) = delete;
+  ~Impl() {
+    BN_clear_free(big_num);
+  }
+};
+
+BigNum::BigNum() : impl_(make_unique<Impl>()) {
+}
+
+BigNum::BigNum(const BigNum &other) : BigNum() {
+  *this = other;
+}
+
+BigNum &BigNum::operator=(const BigNum &other) {
+  CHECK(impl_ != nullptr);
+  CHECK(other.impl_ != nullptr);
+  BIGNUM *result = BN_copy(impl_->big_num, other.impl_->big_num);
+  LOG_IF(FATAL, result == nullptr);
+  return *this;
+}
+
+BigNum::BigNum(BigNum &&other) = default;
+
+BigNum &BigNum::operator=(BigNum &&other) = default;
+
+BigNum::~BigNum() = default;
+
+BigNum BigNum::from_binary(Slice str) {
+  return BigNum(make_unique<Impl>(BN_bin2bn(str.ubegin(), narrow_cast<int>(str.size()), nullptr)));
+}
+
+BigNum BigNum::from_decimal(CSlice str) {
+  BigNum result;
+  int err = BN_dec2bn(&result.impl_->big_num, str.c_str());
+  LOG_IF(FATAL, err == 0);
+  return result;
+}
+
+BigNum BigNum::from_raw(void *openssl_big_num) {
+  return BigNum(make_unique<Impl>(static_cast<BIGNUM *>(openssl_big_num)));
+}
+
+BigNum::BigNum(unique_ptr<Impl> &&impl) : impl_(std::move(impl)) {
+}
+
+void BigNum::ensure_const_time() {
+  BN_set_flags(impl_->big_num, BN_FLG_CONSTTIME);
+}
+
+int BigNum::get_num_bits() const {
+  return BN_num_bits(impl_->big_num);
+}
+
+int BigNum::get_num_bytes() const {
+  return BN_num_bytes(impl_->big_num);
+}
+
+void BigNum::set_bit(int num) {
+  int result = BN_set_bit(impl_->big_num, num);
+  LOG_IF(FATAL, result != 1);
+}
+
+void BigNum::clear_bit(int num) {
+  int result = BN_clear_bit(impl_->big_num, num);
+  LOG_IF(FATAL, result != 1);
+}
+
+bool BigNum::is_bit_set(int num) const {
+  return BN_is_bit_set(impl_->big_num, num) != 0;
+}
+
+bool BigNum::is_prime(BigNumContext &context) const {
+  int result = BN_is_prime_ex(impl_->big_num, BN_prime_checks, context.impl_->big_num_context, nullptr);
+  LOG_IF(FATAL, result == -1);
+  return result == 1;
+}
+
+void BigNum::operator+=(uint32 value) {
+  int result = BN_add_word(impl_->big_num, value);
+  LOG_IF(FATAL, result != 1);
+}
+
+void BigNum::operator-=(uint32 value) {
+  int result = BN_sub_word(impl_->big_num, value);
+  LOG_IF(FATAL, result != 1);
+}
+
+void BigNum::operator*=(uint32 value) {
+  int result = BN_mul_word(impl_->big_num, value);
+  LOG_IF(FATAL, result != 1);
+}
+
+void BigNum::operator/=(uint32 value) {
+  BN_ULONG result = BN_div_word(impl_->big_num, value);
+  LOG_IF(FATAL, result == static_cast<BN_ULONG>(-1));
+}
+
+uint32 BigNum::operator%(uint32 value) const {
+  BN_ULONG result = BN_mod_word(impl_->big_num, value);
+  LOG_IF(FATAL, result == static_cast<BN_ULONG>(-1));
+  return narrow_cast<uint32>(result);
+}
+
+void BigNum::set_value(uint32 new_value) {
+  if (new_value == 0) {
+    BN_zero(impl_->big_num);
+  } else {
+    int result = BN_set_word(impl_->big_num, new_value);
+    LOG_IF(FATAL, result != 1);
+  }
+}
+
+BigNum BigNum::clone() const {
+  BIGNUM *result = BN_dup(impl_->big_num);
+  LOG_IF(FATAL, result == nullptr);
+  return BigNum(make_unique<Impl>(result));
+}
+
+string BigNum::to_binary(int exact_size) const {
+  int num_size = get_num_bytes();
+  if (exact_size == -1) {
+    exact_size = num_size;
+  } else {
+    CHECK(exact_size >= num_size);
+  }
+  string res(exact_size, '\0');
+  BN_bn2bin(impl_->big_num, reinterpret_cast<unsigned char *>(&res[exact_size - num_size]));
+  return res;
+}
+
+string BigNum::to_decimal() const {
+  char *result = BN_bn2dec(impl_->big_num);
+  CHECK(result != nullptr);
+  string res(result);
+  OPENSSL_free(result);
+  return res;
+}
+
+void BigNum::random(BigNum &r, int bits, int top, int bottom) {
+  int result = BN_rand(r.impl_->big_num, bits, top, bottom);
+  LOG_IF(FATAL, result != 1);
+}
+
+void BigNum::add(BigNum &r, const BigNum &a, const BigNum &b) {
+  int result = BN_add(r.impl_->big_num, a.impl_->big_num, b.impl_->big_num);
+  LOG_IF(FATAL, result != 1);
+}
+
+void BigNum::sub(BigNum &r, const BigNum &a, const BigNum &b) {
+  CHECK(r.impl_->big_num != a.impl_->big_num);
+  CHECK(r.impl_->big_num != b.impl_->big_num);
+  int result = BN_sub(r.impl_->big_num, a.impl_->big_num, b.impl_->big_num);
+  LOG_IF(FATAL, result != 1);
+}
+
+void BigNum::mul(BigNum &r, BigNum &a, BigNum &b, BigNumContext &context) {
+  int result = BN_mul(r.impl_->big_num, a.impl_->big_num, b.impl_->big_num, context.impl_->big_num_context);
+  LOG_IF(FATAL, result != 1);
+}
+
+void BigNum::mod_mul(BigNum &r, BigNum &a, BigNum &b, const BigNum &m, BigNumContext &context) {
+  int result = BN_mod_mul(r.impl_->big_num, a.impl_->big_num, b.impl_->big_num, m.impl_->big_num,
+                          context.impl_->big_num_context);
+  LOG_IF(FATAL, result != 1);
+}
+
+void BigNum::div(BigNum *quotient, BigNum *remainder, const BigNum &dividend, const BigNum &divisor,
+                 BigNumContext &context) {
+  auto q = quotient == nullptr ? nullptr : quotient->impl_->big_num;
+  auto r = remainder == nullptr ? nullptr : remainder->impl_->big_num;
+  if (q == nullptr && r == nullptr) {
+    return;
+  }
+
+  auto result = BN_div(q, r, dividend.impl_->big_num, divisor.impl_->big_num, context.impl_->big_num_context);
+  LOG_IF(FATAL, result != 1);
+}
+
+void BigNum::mod_exp(BigNum &r, const BigNum &a, const BigNum &p, const BigNum &m, BigNumContext &context) {
+  int result = BN_mod_exp(r.impl_->big_num, a.impl_->big_num, p.impl_->big_num, m.impl_->big_num,
+                          context.impl_->big_num_context);
+  LOG_IF(FATAL, result != 1);
+}
+
+void BigNum::gcd(BigNum &r, BigNum &a, BigNum &b, BigNumContext &context) {
+  int result = BN_gcd(r.impl_->big_num, a.impl_->big_num, b.impl_->big_num, context.impl_->big_num_context);
+  LOG_IF(FATAL, result != 1);
+}
+
+int BigNum::compare(const BigNum &a, const BigNum &b) {
+  return BN_cmp(a.impl_->big_num, b.impl_->big_num);
+}
+
+}  // namespace td
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/BigNum.h b/libs/tdlib/td/tdutils/td/utils/BigNum.h
new file mode 100644
index 0000000000..6eecdeab03
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/BigNum.h
@@ -0,0 +1,108 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+#if TD_HAVE_OPENSSL
+
+#include "td/utils/Slice.h"
+
+namespace td {
+
+class BigNumContext {
+ public:
+  BigNumContext();
+  BigNumContext(const BigNumContext &other) = delete;
+  BigNumContext &operator=(const BigNumContext &other) = delete;
+  BigNumContext(BigNumContext &&other);
+  BigNumContext &operator=(BigNumContext &&other);
+  ~BigNumContext();
+
+ private:
+  class Impl;
+  unique_ptr<Impl> impl_;
+
+  friend class BigNum;
+};
+
+class BigNum {
+ public:
+  BigNum();
+  BigNum(const BigNum &other);
+  BigNum &operator=(const BigNum &other);
+  BigNum(BigNum &&other);
+  BigNum &operator=(BigNum &&other);
+  ~BigNum();
+
+  static BigNum from_binary(Slice str);
+
+  static BigNum from_decimal(CSlice str);
+
+  static BigNum from_raw(void *openssl_big_num);
+
+  void set_value(uint32 new_value);
+
+  void ensure_const_time();
+
+  int get_num_bits() const;
+
+  int get_num_bytes() const;
+
+  void set_bit(int num);
+
+  void clear_bit(int num);
+
+  bool is_bit_set(int num) const;
+
+  bool is_prime(BigNumContext &context) const;
+
+  BigNum clone() const;
+
+  string to_binary(int exact_size = -1) const;
+
+  string to_decimal() const;
+
+  void operator+=(uint32 value);
+
+  void operator-=(uint32 value);
+
+  void operator*=(uint32 value);
+
+  void operator/=(uint32 value);
+
+  uint32 operator%(uint32 value) const;
+
+  static void random(BigNum &r, int bits, int top, int bottom);
+
+  static void add(BigNum &r, const BigNum &a, const BigNum &b);
+
+  static void sub(BigNum &r, const BigNum &a, const BigNum &b);
+
+  static void mul(BigNum &r, BigNum &a, BigNum &b, BigNumContext &context);
+
+  static void mod_mul(BigNum &r, BigNum &a, BigNum &b, const BigNum &m, BigNumContext &context);
+
+  static void div(BigNum *quotient, BigNum *remainder, const BigNum &dividend, const BigNum &divisor,
+                  BigNumContext &context);
+
+  static void mod_exp(BigNum &r, const BigNum &a, const BigNum &p, const BigNum &m, BigNumContext &context);
+
+  static void gcd(BigNum &r, BigNum &a, BigNum &b, BigNumContext &context);
+
+  static int compare(const BigNum &a, const BigNum &b);
+
+ private:
+  class Impl;
+  unique_ptr<Impl> impl_;
+
+  explicit BigNum(unique_ptr<Impl> &&impl);
+};
+
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/BufferedFd.h b/libs/tdlib/td/tdutils/td/utils/BufferedFd.h
new file mode 100644
index 0000000000..0c8f65408d
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/BufferedFd.h
@@ -0,0 +1,199 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/buffer.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <limits>
+
+namespace td {
+// just reads from given reader and writes to given writer
+template <class FdT>
+class BufferedFdBase : public FdT {
+ public:
+  BufferedFdBase() = default;
+  explicit BufferedFdBase(FdT &&fd_);
+  // TODO: make move constructor and move assignment safer
+
+  Result<size_t> flush_read(size_t max_read = std::numeric_limits<size_t>::max()) TD_WARN_UNUSED_RESULT;
+  Result<size_t> flush_write() TD_WARN_UNUSED_RESULT;
+
+  bool need_flush_write(size_t at_least = 0) {
+    CHECK(write_);
+    write_->sync_with_writer();
+    return write_->size() > at_least;
+  }
+  size_t ready_for_flush_write() {
+    CHECK(write_);
+    write_->sync_with_writer();
+    return write_->size();
+  }
+  void set_input_writer(ChainBufferWriter *read) {
+    read_ = read;
+  }
+  void set_output_reader(ChainBufferReader *write) {
+    write_ = write;
+  }
+
+ private:
+  ChainBufferWriter *read_ = nullptr;
+  ChainBufferReader *write_ = nullptr;
+};
+
+template <class FdT>
+class BufferedFd : public BufferedFdBase<FdT> {
+  using Parent = BufferedFdBase<FdT>;
+  ChainBufferWriter input_writer_;
+  ChainBufferReader input_reader_;
+  ChainBufferWriter output_writer_;
+  ChainBufferReader output_reader_;
+  void init();
+  void init_ptr();
+
+ public:
+  BufferedFd();
+  explicit BufferedFd(FdT &&fd_);
+  BufferedFd(BufferedFd &&);
+  BufferedFd &operator=(BufferedFd &&);
+  BufferedFd(const BufferedFd &) = delete;
+  BufferedFd &operator=(const BufferedFd &) = delete;
+  ~BufferedFd();
+
+  void close();
+
+  Result<size_t> flush_read(size_t max_read = std::numeric_limits<size_t>::max()) TD_WARN_UNUSED_RESULT;
+  Result<size_t> flush_write() TD_WARN_UNUSED_RESULT;
+
+  // Yep, direct access to buffers. It is IO interface too.
+  ChainBufferReader &input_buffer();
+  ChainBufferWriter &output_buffer();
+};
+
+// IMPLEMENTATION
+
+/*** BufferedFd ***/
+template <class FdT>
+BufferedFdBase<FdT>::BufferedFdBase(FdT &&fd_) : FdT(std::move(fd_)) {
+}
+
+template <class FdT>
+Result<size_t> BufferedFdBase<FdT>::flush_read(size_t max_read) {
+  CHECK(read_);
+  size_t result = 0;
+  while (::td::can_read(*this) && max_read) {
+    MutableSlice slice = read_->prepare_append().truncate(max_read);
+    TRY_RESULT(x, FdT::read(slice));
+    slice.truncate(x);
+    read_->confirm_append(x);
+    result += x;
+    max_read -= x;
+  }
+  return result;
+}
+
+template <class FdT>
+Result<size_t> BufferedFdBase<FdT>::flush_write() {
+  size_t result = 0;
+  // TODO: sync on demand
+  write_->sync_with_writer();
+  while (!write_->empty() && ::td::can_write(*this)) {
+    Slice slice = write_->prepare_read();
+    TRY_RESULT(x, FdT::write(slice));
+    write_->confirm_read(x);
+    result += x;
+  }
+  return result;
+}
+
+/*** BufferedFd ***/
+template <class FdT>
+void BufferedFd<FdT>::init() {
+  input_reader_ = input_writer_.extract_reader();
+  output_reader_ = output_writer_.extract_reader();
+  init_ptr();
+}
+
+template <class FdT>
+void BufferedFd<FdT>::init_ptr() {
+  this->set_input_writer(&input_writer_);
+  this->set_output_reader(&output_reader_);
+}
+
+template <class FdT>
+BufferedFd<FdT>::BufferedFd() {
+  init();
+}
+
+template <class FdT>
+BufferedFd<FdT>::BufferedFd(FdT &&fd_) : Parent(std::move(fd_)) {
+  init();
+}
+
+template <class FdT>
+BufferedFd<FdT>::BufferedFd(BufferedFd &&from) {
+  *this = std::move(from);
+}
+
+template <class FdT>
+BufferedFd<FdT> &BufferedFd<FdT>::operator=(BufferedFd &&from) {
+  FdT::operator=(std::move(static_cast<FdT &>(from)));
+  input_reader_ = std::move(from.input_reader_);
+  input_writer_ = std::move(from.input_writer_);
+  output_reader_ = std::move(from.output_reader_);
+  output_writer_ = std::move(from.output_writer_);
+  init_ptr();
+  return *this;
+}
+
+template <class FdT>
+BufferedFd<FdT>::~BufferedFd() {
+  close();
+}
+
+template <class FdT>
+void BufferedFd<FdT>::close() {
+  FdT::close();
+  // TODO: clear buffers
+}
+
+template <class FdT>
+Result<size_t> BufferedFd<FdT>::flush_read(size_t max_read) {
+  TRY_RESULT(result, Parent::flush_read(max_read));
+  if (result) {
+    // TODO: faster sync is possible if you owns writer.
+    input_reader_.sync_with_writer();
+    LOG(DEBUG) << "flush_read: +" << format::as_size(result) << tag("total", format::as_size(input_reader_.size()));
+  }
+  return result;
+}
+
+template <class FdT>
+Result<size_t> BufferedFd<FdT>::flush_write() {
+  TRY_RESULT(result, Parent::flush_write());
+  if (result) {
+    LOG(DEBUG) << "flush_write: +" << format::as_size(result) << tag("left", format::as_size(output_reader_.size()));
+  }
+  return result;
+}
+
+// Yep, direct access to buffers. It is IO interface too.
+template <class FdT>
+ChainBufferReader &BufferedFd<FdT>::input_buffer() {
+  return input_reader_;
+}
+
+template <class FdT>
+ChainBufferWriter &BufferedFd<FdT>::output_buffer() {
+  return output_writer_;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/BufferedReader.h b/libs/tdlib/td/tdutils/td/utils/BufferedReader.h
new file mode 100644
index 0000000000..9006d78132
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/BufferedReader.h
@@ -0,0 +1,61 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <cstring>
+
+namespace td {
+class BufferedReader {
+ public:
+  explciit BufferedReader(FileFd &file, size_t buff_size = 8152)
+      : file_(file), buff_(buff_size), begin_pos_(0), end_pos_(0) {
+  }
+
+  Result<size_t> read(MutableSlice slice) TD_WARN_UNUSED_RESULT;
+
+ private:
+  FileFd &file_;
+  vector<char> buff_;
+  size_t begin_pos_;
+  size_t end_pos_;
+};
+
+inline Result<size_t> BufferedReader::read(MutableSlice slice) {
+  size_t available = end_pos_ - begin_pos_;
+  if (available >= slice.size()) {
+    // have enough data in buffer
+    std::memcpy(slice.begin(), &buff_[begin_pos_], slice.size());
+    begin_pos_ += slice.size();
+    return slice.size();
+  }
+
+  if (available) {
+    std::memcpy(slice.begin(), &buff_[begin_pos_], available);
+    begin_pos_ += available;
+    slice.remove_prefix(available);
+  }
+
+  if (slice.size() > buff_.size() / 2) {
+    TRY_RESULT(result, file_.read(slice));
+    return result + available;
+  }
+
+  TRY_RESULT(result, file_.read({&buff_[0], buff_.size()}));
+  begin_pos_ = 0;
+  end_pos_ = result;
+
+  size_t left = min(end_pos_, slice.size());
+  std::memcpy(slice.begin(), &buff_[begin_pos_], left);
+  begin_pos_ += left;
+  return left + available;
+}
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/ByteFlow.h b/libs/tdlib/td/tdutils/td/utils/ByteFlow.h
new file mode 100644
index 0000000000..fb0c4489eb
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/ByteFlow.h
@@ -0,0 +1,288 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+class ByteFlowInterface {
+ public:
+  virtual void close_input(Status status) = 0;
+  virtual void wakeup() = 0;
+  virtual void set_parent(ByteFlowInterface &other) = 0;
+  virtual void set_input(ChainBufferReader *input) = 0;
+  virtual size_t get_need_size() = 0;
+  ByteFlowInterface() = default;
+  ByteFlowInterface(const ByteFlowInterface &) = delete;
+  ByteFlowInterface &operator=(const ByteFlowInterface &) = delete;
+  ByteFlowInterface(ByteFlowInterface &&) = default;
+  ByteFlowInterface &operator=(ByteFlowInterface &&) = default;
+  virtual ~ByteFlowInterface() = default;
+};
+
+class ByteFlowBaseCommon : public ByteFlowInterface {
+ public:
+  ByteFlowBaseCommon() = default;
+
+  void close_input(Status status) final {
+    if (status.is_error()) {
+      finish(std::move(status));
+    } else {
+      is_input_active_ = false;
+      wakeup();
+    }
+  }
+
+  void wakeup() final {
+    if (stop_flag_) {
+      return;
+    }
+    input_->sync_with_writer();
+    if (waiting_flag_) {
+      if (!is_input_active_) {
+        finish(Status::OK());
+      }
+      return;
+    }
+    if (is_input_active_) {
+      if (need_size_ != 0 && input_->size() < need_size_) {
+        return;
+      }
+    }
+    need_size_ = 0;
+    loop();
+  }
+
+  size_t get_need_size() final {
+    return need_size_;
+  }
+
+  virtual void loop() = 0;
+
+ protected:
+  bool waiting_flag_ = false;
+  ChainBufferReader *input_;
+  bool is_input_active_ = true;
+  size_t need_size_ = 0;
+  void finish(Status status) {
+    stop_flag_ = true;
+    need_size_ = 0;
+    if (parent_) {
+      parent_->close_input(std::move(status));
+      parent_ = nullptr;
+    }
+  }
+
+  void set_need_size(size_t need_size) {
+    need_size_ = need_size;
+  }
+
+  void on_output_updated() {
+    if (parent_) {
+      parent_->wakeup();
+    }
+  }
+  void consume_input() {
+    waiting_flag_ = true;
+    if (!is_input_active_) {
+      finish(Status::OK());
+    }
+  }
+
+ private:
+  ByteFlowInterface *parent_ = nullptr;
+  bool stop_flag_ = false;
+  friend class ByteFlowBase;
+  friend class ByteFlowInplaceBase;
+};
+
+class ByteFlowBase : public ByteFlowBaseCommon {
+ public:
+  ByteFlowBase() = default;
+
+  void set_input(ChainBufferReader *input) final {
+    input_ = input;
+  }
+  void set_parent(ByteFlowInterface &other) final {
+    parent_ = &other;
+    parent_->set_input(&output_reader_);
+  }
+  void loop() override = 0;
+
+  // ChainBufferWriter &get_output() {
+  // return output_;
+  //}
+
+ protected:
+  ChainBufferWriter output_;
+  ChainBufferReader output_reader_ = output_.extract_reader();
+};
+
+class ByteFlowInplaceBase : public ByteFlowBaseCommon {
+ public:
+  ByteFlowInplaceBase() = default;
+
+  void set_input(ChainBufferReader *input) final {
+    input_ = input;
+    output_ = ChainBufferReader(input_->begin().clone(), input_->begin().clone(), false);
+  }
+  void set_parent(ByteFlowInterface &other) final {
+    parent_ = &other;
+    parent_->set_input(&output_);
+  }
+  void loop() override = 0;
+
+  ChainBufferReader &get_output() {
+    return output_;
+  }
+
+ protected:
+  ChainBufferReader output_;
+};
+
+inline ByteFlowInterface &operator>>(ByteFlowInterface &from, ByteFlowInterface &to) {
+  from.set_parent(to);
+  return to;
+}
+
+class ByteFlowSource : public ByteFlowInterface {
+ public:
+  ByteFlowSource() = default;
+  explicit ByteFlowSource(ChainBufferReader *buffer) : buffer_(buffer) {
+  }
+  ByteFlowSource(ByteFlowSource &&other) : buffer_(other.buffer_), parent_(other.parent_) {
+    other.buffer_ = nullptr;
+    other.parent_ = nullptr;
+  }
+  ByteFlowSource &operator=(ByteFlowSource &&other) {
+    buffer_ = other.buffer_;
+    parent_ = other.parent_;
+    other.buffer_ = nullptr;
+    other.parent_ = nullptr;
+    return *this;
+  }
+  ByteFlowSource(const ByteFlowSource &) = delete;
+  ByteFlowSource &operator=(const ByteFlowSource &) = delete;
+  ~ByteFlowSource() override = default;
+
+  void set_input(ChainBufferReader *) final {
+    UNREACHABLE();
+  }
+  void set_parent(ByteFlowInterface &parent) final {
+    CHECK(parent_ == nullptr);
+    parent_ = &parent;
+    parent_->set_input(buffer_);
+  }
+  void close_input(Status status) final {
+    CHECK(parent_);
+    parent_->close_input(std::move(status));
+    parent_ = nullptr;
+  }
+  void wakeup() final {
+    CHECK(parent_);
+    parent_->wakeup();
+  }
+  size_t get_need_size() final {
+    if (parent_ == nullptr) {
+      return 0;
+    }
+    return parent_->get_need_size();
+  }
+
+ private:
+  ChainBufferReader *buffer_ = nullptr;
+  ByteFlowInterface *parent_ = nullptr;
+};
+
+class ByteFlowSink : public ByteFlowInterface {
+ public:
+  void set_input(ChainBufferReader *input) final {
+    CHECK(buffer_ == nullptr);
+    buffer_ = input;
+  }
+  void set_parent(ByteFlowInterface &parent) final {
+    UNREACHABLE();
+  }
+  void close_input(Status status) final {
+    CHECK(active_);
+    active_ = false;
+    status_ = std::move(status);
+    buffer_->sync_with_writer();
+  }
+  void wakeup() final {
+    buffer_->sync_with_writer();
+  }
+  size_t get_need_size() final {
+    UNREACHABLE();
+    return 0;
+  }
+  bool is_ready() {
+    return !active_;
+  }
+  Status &status() {
+    return status_;
+  }
+  ChainBufferReader *result() {
+    CHECK(is_ready() && status().is_ok());
+    return buffer_;
+  }
+  ChainBufferReader *get_output() {
+    return buffer_;
+  }
+
+ private:
+  bool active_ = true;
+  Status status_;
+  ChainBufferReader *buffer_ = nullptr;
+};
+
+class ByteFlowMoveSink : public ByteFlowInterface {
+ public:
+  void set_input(ChainBufferReader *input) final {
+    CHECK(!input_);
+    input_ = input;
+  }
+  void set_parent(ByteFlowInterface &parent) final {
+    UNREACHABLE();
+  }
+  void close_input(Status status) final {
+    CHECK(active_);
+    active_ = false;
+    status_ = std::move(status);
+    wakeup();
+  }
+  void wakeup() final {
+    input_->sync_with_writer();
+    output_->append(*input_);
+  }
+  size_t get_need_size() final {
+    UNREACHABLE();
+    return 0;
+  }
+  void set_output(ChainBufferWriter *output) {
+    CHECK(!output_);
+    output_ = output;
+  }
+
+  bool is_ready() {
+    return !active_;
+  }
+  Status &status() {
+    return status_;
+  }
+
+ private:
+  bool active_ = true;
+  Status status_;
+  ChainBufferReader *input_ = nullptr;
+  ChainBufferWriter *output_ = nullptr;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/ChangesProcessor.h b/libs/tdlib/td/tdutils/td/utils/ChangesProcessor.h
new file mode 100644
index 0000000000..9342f45a8b
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/ChangesProcessor.h
@@ -0,0 +1,61 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+#include <utility>
+
+namespace td {
+
+// Process changes after they are finished in order of addition
+template <class DataT>
+class ChangesProcessor {
+ public:
+  using Id = uint64;
+
+  void clear() {
+    offset_ += data_array_.size();
+    ready_i_ = 0;
+    data_array_.clear();
+  }
+
+  template <class FromDataT>
+  Id add(FromDataT &&data) {
+    auto res = offset_ + data_array_.size();
+    data_array_.emplace_back(std::forward<DataT>(data), false);
+    return static_cast<Id>(res);
+  }
+
+  template <class F>
+  void finish(Id token, F &&func) {
+    size_t pos = static_cast<size_t>(token) - offset_;
+    if (pos >= data_array_.size()) {
+      return;
+    }
+    data_array_[pos].second = true;
+    while (ready_i_ < data_array_.size() && data_array_[ready_i_].second == true) {
+      func(std::move(data_array_[ready_i_].first));
+      ready_i_++;
+    }
+    try_compactify();
+  }
+
+ private:
+  size_t offset_ = 1;
+  size_t ready_i_ = 0;
+  std::vector<std::pair<DataT, bool>> data_array_;
+  void try_compactify() {
+    if (ready_i_ > 5 && ready_i_ * 2 > data_array_.size()) {
+      data_array_.erase(data_array_.begin(), data_array_.begin() + ready_i_);
+      offset_ += ready_i_;
+      ready_i_ = 0;
+    }
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Closure.h b/libs/tdlib/td/tdutils/td/utils/Closure.h
new file mode 100644
index 0000000000..718f930b8a
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Closure.h
@@ -0,0 +1,169 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/invoke.h"
+#include "td/utils/logging.h"
+
+#include <cstdlib>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+
+//
+// Essentially we have:
+// (ActorT::func, arg1, arg2, ..., argn)
+// We want to call:
+// actor->func(arg1, arg2, ..., argn)
+// And in some cases we would like to delay this call.
+//
+// First attempt would be
+// [a1=arg1, a2=arg2, ..., an=argn](ActorT *actor) {
+//   actor->func(a1, a2, ..., an)
+// }
+//
+// But there are some difficulties with elimitation on unnecessary copies.
+// We want to use move constructor when it is possible
+//
+// We may pass
+// Tmp. Temporary / rvalue reference
+// Var. Variable / reference
+// CnstRef. const reference
+//
+//
+// Function may expect
+// Val. Value
+// CnstRef. const reference
+// Ref. rvalue reverence / reference
+//
+// TODO:
+//    Immediate call / Delayed call
+// Tmp->Val       move / move->move
+// Tmp->CnstRef      + / move->+
+// Tmp->Ref          + / move->+
+// Var->Val       copy / copy->move
+// Var->CnstRef      + / copy->
+// Var->Ref          + / copy->+   // khm. It will complile, but won't work
+//
+// So I will use common idiom: forward references
+// If delay is needed, just std::forward data to temporary storage, and std::move them when call is executed.
+//
+//
+// create_immediate_closure(&Actor::func, arg1, arg2, ..., argn).run(actor)
+// to_delayed_closure(std::move(immediate)).run(actor)
+
+namespace td {
+template <class ActorT, class FunctionT, class... ArgsT>
+class DelayedClosure;
+
+template <class ActorT, class FunctionT, class... ArgsT>
+class ImmediateClosure {
+ public:
+  using Delayed = DelayedClosure<ActorT, FunctionT, ArgsT...>;
+  friend Delayed;
+  using ActorType = ActorT;
+
+  void run(ActorT *actor) {
+    mem_call_tuple(actor, func, std::move(args));
+  }
+
+  // no &&. just save references as references.
+  explicit ImmediateClosure(FunctionT func, ArgsT... args) : func(func), args(std::forward<ArgsT>(args)...) {
+  }
+
+ private:
+  FunctionT func;
+  std::tuple<ArgsT...> args;
+};
+
+template <class ActorT, class ResultT, class... DestArgsT, class... SrcArgsT>
+ImmediateClosure<ActorT, ResultT (ActorT::*)(DestArgsT...), SrcArgsT &&...> create_immediate_closure(
+    ResultT (ActorT::*func)(DestArgsT...), SrcArgsT &&... args) {
+  return ImmediateClosure<ActorT, ResultT (ActorT::*)(DestArgsT...), SrcArgsT &&...>(func,
+                                                                                     std::forward<SrcArgsT>(args)...);
+}
+
+template <class ActorT, class FunctionT, class... ArgsT>
+class DelayedClosure {
+ public:
+  using ActorType = ActorT;
+  using Delayed = DelayedClosure<ActorT, FunctionT, ArgsT...>;
+
+  void run(ActorT *actor) {
+    mem_call_tuple(actor, func, std::move(args));
+  }
+
+  DelayedClosure clone() const {
+    return do_clone(*this);
+  }
+
+  explicit DelayedClosure(ImmediateClosure<ActorT, FunctionT, ArgsT...> &&other)
+      : func(std::move(other.func)), args(std::move(other.args)) {
+  }
+
+  explicit DelayedClosure(FunctionT func, ArgsT... args) : func(func), args(std::forward<ArgsT>(args)...) {
+  }
+
+  template <class F>
+  void for_each(const F &f) {
+    tuple_for_each(args, f);
+  }
+
+ private:
+  using ArgsStorageT = std::tuple<typename std::decay<ArgsT>::type...>;
+
+  FunctionT func;
+  ArgsStorageT args;
+
+  template <class FromActorT, class FromFunctionT, class... FromArgsT>
+  explicit DelayedClosure(const DelayedClosure<FromActorT, FromFunctionT, FromArgsT...> &other,
+                          std::enable_if_t<LogicAnd<std::is_copy_constructible<FromArgsT>::value...>::value, int> = 0)
+      : func(other.func), args(other.args) {
+  }
+
+  template <class FromActorT, class FromFunctionT, class... FromArgsT>
+  explicit DelayedClosure(
+      const DelayedClosure<FromActorT, FromFunctionT, FromArgsT...> &other,
+      std::enable_if_t<!LogicAnd<std::is_copy_constructible<FromArgsT>::value...>::value, int> = 0) {
+    LOG(FATAL) << "Deleted constructor";
+    std::abort();
+  }
+
+  template <class FromActorT, class FromFunctionT, class... FromArgsT>
+  std::enable_if_t<!LogicAnd<std::is_copy_constructible<FromArgsT>::value...>::value,
+                   DelayedClosure<FromActorT, FromFunctionT, FromArgsT...>>
+  do_clone(const DelayedClosure<FromActorT, FromFunctionT, FromArgsT...> &value) const {
+    LOG(FATAL) << "Trying to clone DelayedClosure that contains noncopyable elements";
+    std::abort();
+  }
+
+  template <class FromActorT, class FromFunctionT, class... FromArgsT>
+  std::enable_if_t<LogicAnd<std::is_copy_constructible<FromArgsT>::value...>::value,
+                   DelayedClosure<FromActorT, FromFunctionT, FromArgsT...>>
+  do_clone(const DelayedClosure<FromActorT, FromFunctionT, FromArgsT...> &value) const {
+    return DelayedClosure<FromActorT, FromFunctionT, FromArgsT...>(value);
+  }
+};
+
+template <class... ArgsT>
+typename ImmediateClosure<ArgsT...>::Delayed to_delayed_closure(ImmediateClosure<ArgsT...> &&other) {
+  return typename ImmediateClosure<ArgsT...>::Delayed(std::move(other));
+}
+
+template <class... ArgsT>
+DelayedClosure<ArgsT...> to_delayed_closure(DelayedClosure<ArgsT...> &&other) {
+  return std::move(other);
+}
+
+template <class ActorT, class ResultT, class... DestArgsT, class... SrcArgsT>
+auto create_delayed_closure(ResultT (ActorT::*func)(DestArgsT...), SrcArgsT &&... args) {
+  return DelayedClosure<ActorT, ResultT (ActorT::*)(DestArgsT...), SrcArgsT &&...>(func,
+                                                                                   std::forward<SrcArgsT>(args)...);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Container.h b/libs/tdlib/td/tdutils/td/utils/Container.h
new file mode 100644
index 0000000000..57b4bb4d16
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Container.h
@@ -0,0 +1,149 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+
+#include <limits>
+
+namespace td {
+
+// 1. Allocates all objects in vector. (but vector never shrinks)
+// 2. Id is safe way to reach this object.
+// 3. All ids are unique.
+// 4. All ids are non-zero.
+template <class DataT>
+class Container {
+ public:
+  using Id = uint64;
+  DataT *get(Id id) {
+    int32 slot_id = decode_id(id);
+    if (slot_id == -1) {
+      return nullptr;
+    }
+    return &slots_[slot_id].data;
+  }
+
+  void erase(Id id) {
+    int32 slot_id = decode_id(id);
+    if (slot_id == -1) {
+      return;
+    }
+    release(slot_id);
+  }
+
+  DataT extract(Id id) {
+    int32 slot_id = decode_id(id);
+    CHECK(slot_id != -1);
+    auto res = std::move(slots_[slot_id].data);
+    release(slot_id);
+    return res;
+  }
+
+  Id create(DataT &&data = DataT(), uint8 type = 0) {
+    int32 id = store(std::move(data), type);
+    return encode_id(id);
+  }
+
+  Id reset_id(Id id) {
+    int32 slot_id = decode_id(id);
+    CHECK(slot_id != -1);
+    inc_generation(slot_id);
+    return encode_id(slot_id);
+  }
+
+  static uint8 type_from_id(Id id) {
+    return static_cast<uint8>(id);
+  }
+
+  vector<Id> ids() {
+    vector<bool> is_bad(slots_.size(), false);
+    for (auto id : empty_slots_) {
+      is_bad[id] = true;
+    }
+    vector<Id> res;
+    for (size_t i = 0, n = slots_.size(); i < n; i++) {
+      if (!is_bad[i]) {
+        res.push_back(encode_id(static_cast<int32>(i)));
+      }
+    }
+    return res;
+  }
+  template <class F>
+  void for_each(const F &f) {
+    auto ids = this->ids();
+    for (auto id : ids) {
+      f(id, *get(id));
+    }
+  }
+  size_t size() const {
+    CHECK(empty_slots_.size() <= slots_.size());
+    return slots_.size() - empty_slots_.size();
+  }
+  bool empty() const {
+    return size() == 0;
+  }
+  void clear() {
+    *this = Container<DataT>();
+  }
+
+ private:
+  static constexpr uint32 GENERATION_STEP = 1 << 8;
+  static constexpr uint32 TYPE_MASK = (1 << 8) - 1;
+  struct Slot {
+    uint32 generation;
+    DataT data;
+  };
+  vector<Slot> slots_;
+  vector<int32> empty_slots_;
+
+  Id encode_id(int32 id) const {
+    return (static_cast<uint64>(id) << 32) | slots_[id].generation;
+  }
+
+  int32 decode_id(Id id) const {
+    int32 slot_id = static_cast<int32>(id >> 32);
+    uint32 generation = static_cast<uint32>(id);
+    if (slot_id < 0 || slot_id >= static_cast<int32>(slots_.size())) {
+      return -1;
+    }
+    if (generation != slots_[slot_id].generation) {
+      return -1;
+    }
+    return slot_id;
+  }
+
+  int32 store(DataT &&data, uint8 type) {
+    int32 pos;
+    if (!empty_slots_.empty()) {
+      pos = empty_slots_.back();
+      empty_slots_.pop_back();
+      slots_[pos].data = std::move(data);
+      slots_[pos].generation ^= (slots_[pos].generation & TYPE_MASK) ^ type;
+    } else {
+      CHECK(slots_.size() <= static_cast<size_t>(std::numeric_limits<int32>::max()));
+      pos = static_cast<int32>(slots_.size());
+      slots_.push_back(Slot{GENERATION_STEP + type, std::move(data)});
+    }
+    return pos;
+  }
+
+  void release(int32 id) {
+    inc_generation(id);
+    slots_[id].data = DataT();
+    if (slots_[id].generation & ~TYPE_MASK) {  // generation overflow. Can't use this id anymore
+      empty_slots_.push_back(id);
+    }
+  }
+
+  void inc_generation(int32 id) {
+    slots_[id].generation += GENERATION_STEP;
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Enumerator.h b/libs/tdlib/td/tdutils/td/utils/Enumerator.h
new file mode 100644
index 0000000000..ca7c0493ff
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Enumerator.h
@@ -0,0 +1,45 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+
+#include <map>
+#include <tuple>
+
+namespace td {
+
+template <class ValueT>
+class Enumerator {
+ public:
+  using Key = int32;
+
+  Key add(ValueT v) {
+    int32 next_id = narrow_cast<int32>(arr_.size() + 1);
+    bool was_inserted;
+    decltype(map_.begin()) it;
+    std::tie(it, was_inserted) = map_.emplace(std::move(v), next_id);
+    if (was_inserted) {
+      arr_.push_back(&it->first);
+    }
+    return it->second;
+  }
+
+  const ValueT &get(Key key) const {
+    auto pos = static_cast<size_t>(key - 1);
+    CHECK(pos < arr_.size());
+    return *arr_[pos];
+  }
+
+ private:
+  std::map<ValueT, int32> map_;
+  std::vector<const ValueT *> arr_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/FileLog.cpp b/libs/tdlib/td/tdutils/td/utils/FileLog.cpp
new file mode 100644
index 0000000000..e3c84f1713
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/FileLog.cpp
@@ -0,0 +1,92 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/FileLog.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/port/path.h"
+#include "td/utils/Slice.h"
+
+#include <limits>
+
+namespace td {
+
+bool FileLog::init(string path, int64 rotate_threshold) {
+  if (path == path_) {
+    set_rotate_threshold(rotate_threshold);
+    return true;
+  }
+
+  auto r_fd = FileFd::open(path, FileFd::Create | FileFd::Write | FileFd::Append);
+  if (r_fd.is_error()) {
+    LOG(ERROR) << "Can't open log: " << r_fd.error();
+    return false;
+  }
+
+  fd_.close();
+  fd_ = r_fd.move_as_ok();
+  Fd::duplicate(fd_.get_fd(), Fd::Stderr()).ignore();
+
+  path_ = std::move(path);
+  size_ = fd_.get_size();
+  rotate_threshold_ = rotate_threshold;
+  return true;
+}
+
+void FileLog::set_rotate_threshold(int64 rotate_threshold) {
+  rotate_threshold_ = rotate_threshold;
+}
+
+void FileLog::append(CSlice cslice, int log_level) {
+  Slice slice = cslice;
+  while (!slice.empty()) {
+    auto r_size = fd_.write(slice);
+    if (r_size.is_error()) {
+      process_fatal_error(r_size.error().message());
+    }
+    auto written = r_size.ok();
+    size_ += static_cast<int64>(written);
+    slice.remove_prefix(written);
+  }
+  if (log_level == VERBOSITY_NAME(FATAL)) {
+    process_fatal_error(cslice);
+  }
+
+  if (size_ > rotate_threshold_) {
+    auto status = rename(path_, path_ + ".old");
+    if (status.is_error()) {
+      process_fatal_error(status.message());
+    }
+    do_rotate();
+  }
+}
+
+void FileLog::rotate() {
+  if (path_.empty()) {
+    return;
+  }
+  do_rotate();
+}
+
+void FileLog::do_rotate() {
+  auto current_verbosity_level = GET_VERBOSITY_LEVEL();
+  SET_VERBOSITY_LEVEL(std::numeric_limits<int>::min());  // to ensure that nothing will be printed to the closed log
+  CHECK(!path_.empty());
+  fd_.close();
+  auto r_fd = FileFd::open(path_, FileFd::Create | FileFd::Truncate | FileFd::Write);
+  if (r_fd.is_error()) {
+    process_fatal_error(r_fd.error().message());
+  }
+  fd_ = r_fd.move_as_ok();
+  Fd::duplicate(fd_.get_fd(), Fd::Stderr()).ignore();
+  size_ = 0;
+  SET_VERBOSITY_LEVEL(current_verbosity_level);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/FileLog.h b/libs/tdlib/td/tdutils/td/utils/FileLog.h
new file mode 100644
index 0000000000..12e9d1479a
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/FileLog.h
@@ -0,0 +1,37 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/Slice.h"
+
+namespace td {
+
+class FileLog : public LogInterface {
+  static constexpr int64 DEFAULT_ROTATE_THRESHOLD = 10 * (1 << 20);
+
+ public:
+  bool init(string path, int64 rotate_threshold = DEFAULT_ROTATE_THRESHOLD);
+
+  void set_rotate_threshold(int64 rotate_threshold);
+
+  void append(CSlice cslice, int log_level) override;
+
+  void rotate() override;
+
+ private:
+  FileFd fd_;
+  string path_;
+  int64 size_;
+  int64 rotate_threshold_;
+
+  void do_rotate();
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/FloodControlFast.h b/libs/tdlib/td/tdutils/td/utils/FloodControlFast.h
new file mode 100644
index 0000000000..9f047881aa
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/FloodControlFast.h
@@ -0,0 +1,62 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/TimedStat.h"
+
+namespace td {
+
+class FloodControlFast {
+ public:
+  uint32 add_event(int32 now) {
+    for (auto &limit : limits_) {
+      limit.stat_.add_event(CounterStat::Event(), now);
+      if (limit.stat_.get_stat(now).count_ > limit.count_) {
+        wakeup_at_ = max(wakeup_at_, now + limit.duration_ * 2);
+      }
+    }
+    return wakeup_at_;
+  }
+  uint32 get_wakeup_at() {
+    return wakeup_at_;
+  }
+
+  void add_limit(uint32 duration, int32 count) {
+    limits_.push_back({TimedStat<CounterStat>(duration, 0), duration, count});
+  }
+
+  void clear_events() {
+    for (auto &limit : limits_) {
+      limit.stat_.clear_events();
+    }
+    wakeup_at_ = 0;
+  }
+
+ private:
+  class CounterStat {
+   public:
+    struct Event {};
+    int32 count_ = 0;
+    void on_event(Event e) {
+      count_++;
+    }
+    void clear() {
+      count_ = 0;
+    }
+  };
+
+  uint32 wakeup_at_ = 0;
+  struct Limit {
+    TimedStat<CounterStat> stat_;
+    uint32 duration_;
+    int32 count_;
+  };
+  std::vector<Limit> limits_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/FloodControlStrict.h b/libs/tdlib/td/tdutils/td/utils/FloodControlStrict.h
new file mode 100644
index 0000000000..521fbbedc0
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/FloodControlStrict.h
@@ -0,0 +1,97 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+
+#include <limits>
+
+namespace td {
+
+// More strict implementaions of flood control than FloodControlFast.
+// Should be just fine for small counters.
+class FloodControlStrict {
+ public:
+  int32 add_event(int32 now) {
+    events_.push_back(Event{now});
+    if (without_update_ > 0) {
+      without_update_--;
+    } else {
+      update(now);
+    }
+    return wakeup_at_;
+  }
+
+  // no more than count in each duration.
+  void add_limit(int32 duration, int32 count) {
+    limits_.push_back(Limit{duration, count, 0});
+  }
+
+  int32 get_wakeup_at() {
+    return wakeup_at_;
+  }
+
+  void clear_events() {
+    events_.clear();
+    for (auto &limit : limits_) {
+      limit.pos_ = 0;
+    }
+    without_update_ = 0;
+    wakeup_at_ = 0;
+  }
+
+  int32 update(int32 now) {
+    size_t min_pos = events_.size();
+
+    without_update_ = std::numeric_limits<size_t>::max();
+    for (auto &limit : limits_) {
+      if (limit.pos_ + limit.count_ < events_.size()) {
+        limit.pos_ = events_.size() - limit.count_;
+      }
+
+      // binary-search? :D
+      while (limit.pos_ < events_.size() && events_[limit.pos_].timestamp_ + limit.duration_ < now) {
+        limit.pos_++;
+      }
+
+      if (limit.count_ + limit.pos_ <= events_.size()) {
+        CHECK(limit.count_ + limit.pos_ == events_.size());
+        wakeup_at_ = max(wakeup_at_, events_[limit.pos_].timestamp_ + limit.duration_);
+        without_update_ = 0;
+      } else {
+        without_update_ = min(without_update_, limit.count_ + limit.pos_ - events_.size());
+      }
+
+      min_pos = min(min_pos, limit.pos_);
+    }
+
+    if (min_pos * 2 > events_.size()) {
+      for (auto &limit : limits_) {
+        limit.pos_ -= min_pos;
+      }
+      events_.erase(events_.begin(), events_.begin() + min_pos);
+    }
+    return wakeup_at_;
+  }
+
+ private:
+  int32 wakeup_at_ = 0;
+  struct Event {
+    int32 timestamp_;
+  };
+  struct Limit {
+    int32 duration_;
+    int32 count_;
+    size_t pos_;
+  };
+  size_t without_update_ = 0;
+  std::vector<Event> events_;
+  std::vector<Limit> limits_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/GitInfo.cpp b/libs/tdlib/td/tdutils/td/utils/GitInfo.cpp
new file mode 100644
index 0000000000..976286b923
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/GitInfo.cpp
@@ -0,0 +1,20 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/GitInfo.h"
+
+#include "auto/git_info.h"
+
+namespace td {
+
+CSlice GitInfo::commit() {
+  return GIT_COMMIT;
+}
+bool GitInfo::is_dirty() {
+  return GIT_DIRTY;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/GitInfo.h b/libs/tdlib/td/tdutils/td/utils/GitInfo.h
new file mode 100644
index 0000000000..a3ba32602f
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/GitInfo.h
@@ -0,0 +1,19 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/Slice.h"
+
+namespace td {
+
+class GitInfo {
+ public:
+  static CSlice commit();
+  static bool is_dirty();
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Gzip.cpp b/libs/tdlib/td/tdutils/td/utils/Gzip.cpp
new file mode 100644
index 0000000000..d4e60d6e29
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Gzip.cpp
@@ -0,0 +1,191 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/Gzip.h"
+
+char disable_linker_warning_about_empty_file_gzip_cpp TD_UNUSED;
+
+#if TD_HAVE_ZLIB
+#include "td/utils/logging.h"
+
+#include <cstring>
+#include <limits>
+
+#include <zlib.h>
+
+namespace td {
+
+class Gzip::Impl {
+ public:
+  z_stream stream_;
+
+  // z_stream is not copyable nor movable
+  Impl() = default;
+  Impl(const Impl &other) = delete;
+  Impl &operator=(const Impl &other) = delete;
+  Impl(Impl &&other) = delete;
+  Impl &operator=(Impl &&other) = delete;
+  ~Impl() = default;
+};
+
+Status Gzip::init_encode() {
+  CHECK(mode_ == Empty);
+  init_common();
+  mode_ = Encode;
+  int ret = deflateInit2(&impl_->stream_, 6, Z_DEFLATED, 15, MAX_MEM_LEVEL, Z_DEFAULT_STRATEGY);
+  if (ret != Z_OK) {
+    return Status::Error("zlib deflate init failed");
+  }
+  return Status::OK();
+}
+
+Status Gzip::init_decode() {
+  CHECK(mode_ == Empty);
+  init_common();
+  mode_ = Decode;
+  int ret = inflateInit2(&impl_->stream_, MAX_WBITS + 32);
+  if (ret != Z_OK) {
+    return Status::Error("zlib inflate init failed");
+  }
+  return Status::OK();
+}
+
+void Gzip::set_input(Slice input) {
+  CHECK(input_size_ == 0);
+  CHECK(!close_input_flag_);
+  CHECK(input.size() <= std::numeric_limits<uInt>::max());
+  CHECK(impl_->stream_.avail_in == 0);
+  input_size_ = input.size();
+  impl_->stream_.avail_in = static_cast<uInt>(input.size());
+  impl_->stream_.next_in = reinterpret_cast<Bytef *>(const_cast<char *>(input.data()));
+}
+
+void Gzip::set_output(MutableSlice output) {
+  CHECK(output_size_ == 0);
+  CHECK(output.size() <= std::numeric_limits<uInt>::max());
+  CHECK(impl_->stream_.avail_out == 0);
+  output_size_ = output.size();
+  impl_->stream_.avail_out = static_cast<uInt>(output.size());
+  impl_->stream_.next_out = reinterpret_cast<Bytef *>(output.data());
+}
+
+Result<Gzip::State> Gzip::run() {
+  while (true) {
+    int ret;
+    if (mode_ == Decode) {
+      ret = inflate(&impl_->stream_, Z_NO_FLUSH);
+    } else {
+      ret = deflate(&impl_->stream_, close_input_flag_ ? Z_FINISH : Z_NO_FLUSH);
+    }
+
+    if (ret == Z_OK) {
+      return Running;
+    }
+    if (ret == Z_STREAM_END) {
+      // TODO(now): fail if input is not empty;
+      clear();
+      return Done;
+    }
+    clear();
+    return Status::Error(PSLICE() << "zlib error " << ret);
+  }
+}
+
+size_t Gzip::left_input() const {
+  return impl_->stream_.avail_in;
+}
+size_t Gzip::left_output() const {
+  return impl_->stream_.avail_out;
+}
+
+void Gzip::init_common() {
+  std::memset(&impl_->stream_, 0, sizeof(impl_->stream_));
+  impl_->stream_.zalloc = Z_NULL;
+  impl_->stream_.zfree = Z_NULL;
+  impl_->stream_.opaque = Z_NULL;
+  impl_->stream_.avail_in = 0;
+  impl_->stream_.next_in = nullptr;
+  impl_->stream_.avail_out = 0;
+  impl_->stream_.next_out = nullptr;
+
+  input_size_ = 0;
+  output_size_ = 0;
+
+  close_input_flag_ = false;
+}
+
+void Gzip::clear() {
+  if (mode_ == Decode) {
+    inflateEnd(&impl_->stream_);
+  } else if (mode_ == Encode) {
+    deflateEnd(&impl_->stream_);
+  }
+  mode_ = Empty;
+}
+
+Gzip::Gzip() : impl_(make_unique<Impl>()) {
+}
+
+Gzip::Gzip(Gzip &&other) = default;
+
+Gzip &Gzip::operator=(Gzip &&other) = default;
+
+Gzip::~Gzip() {
+  clear();
+}
+
+BufferSlice gzdecode(Slice s) {
+  Gzip gzip;
+  gzip.init_decode().ensure();
+  auto message = ChainBufferWriter::create_empty();
+  gzip.set_input(s);
+  gzip.close_input();
+  double k = 2;
+  gzip.set_output(message.prepare_append(static_cast<size_t>(static_cast<double>(s.size()) * k)));
+  while (true) {
+    auto r_state = gzip.run();
+    if (r_state.is_error()) {
+      return BufferSlice();
+    }
+    auto state = r_state.ok();
+    if (state == Gzip::Done) {
+      message.confirm_append(gzip.flush_output());
+      break;
+    }
+    if (gzip.need_input()) {
+      return BufferSlice();
+    }
+    if (gzip.need_output()) {
+      message.confirm_append(gzip.flush_output());
+      k *= 1.5;
+      gzip.set_output(message.prepare_append(static_cast<size_t>(static_cast<double>(gzip.left_input()) * k)));
+    }
+  }
+  return message.extract_reader().move_as_buffer_slice();
+}
+
+BufferSlice gzencode(Slice s, double k) {
+  Gzip gzip;
+  gzip.init_encode().ensure();
+  gzip.set_input(s);
+  gzip.close_input();
+  size_t max_size = static_cast<size_t>(static_cast<double>(s.size()) * k);
+  BufferWriter message{max_size};
+  gzip.set_output(message.prepare_append());
+  auto r_state = gzip.run();
+  if (r_state.is_error()) {
+    return BufferSlice();
+  }
+  auto state = r_state.ok();
+  if (state != Gzip::Done) {
+    return BufferSlice();
+  }
+  message.confirm_append(gzip.flush_output());
+  return message.as_buffer_slice();
+}
+
+}  // namespace td
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/Gzip.h b/libs/tdlib/td/tdutils/td/utils/Gzip.h
new file mode 100644
index 0000000000..dd5fba5bf5
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Gzip.h
@@ -0,0 +1,104 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+#if TD_HAVE_ZLIB
+#include "td/utils/buffer.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+class Gzip {
+ public:
+  Gzip();
+  Gzip(const Gzip &) = delete;
+  Gzip &operator=(const Gzip &) = delete;
+  Gzip(Gzip &&other);
+  Gzip &operator=(Gzip &&other);
+  ~Gzip();
+
+  enum Mode { Empty, Encode, Decode };
+  Status init(Mode mode) TD_WARN_UNUSED_RESULT {
+    if (mode == Encode) {
+      return init_encode();
+    } else if (mode == Decode) {
+      return init_decode();
+    }
+    clear();
+    return Status::OK();
+  }
+
+  Status init_encode() TD_WARN_UNUSED_RESULT;
+
+  Status init_decode() TD_WARN_UNUSED_RESULT;
+
+  void set_input(Slice input);
+
+  void set_output(MutableSlice output);
+
+  void close_input() {
+    close_input_flag_ = true;
+  }
+
+  bool need_input() const {
+    return left_input() == 0;
+  }
+
+  bool need_output() const {
+    return left_output() == 0;
+  }
+
+  size_t left_input() const;
+
+  size_t left_output() const;
+
+  size_t used_input() const {
+    return input_size_ - left_input();
+  }
+
+  size_t used_output() const {
+    return output_size_ - left_output();
+  }
+
+  size_t flush_input() {
+    auto res = used_input();
+    input_size_ = left_input();
+    return res;
+  }
+
+  size_t flush_output() {
+    auto res = used_output();
+    output_size_ = left_output();
+    return res;
+  }
+
+  enum State { Running, Done };
+  Result<State> run() TD_WARN_UNUSED_RESULT;
+
+ private:
+  class Impl;
+  unique_ptr<Impl> impl_;
+
+  size_t input_size_ = 0;
+  size_t output_size_ = 0;
+  bool close_input_flag_ = false;
+  Mode mode_ = Empty;
+
+  void init_common();
+  void clear();
+};
+
+BufferSlice gzdecode(Slice s);
+
+BufferSlice gzencode(Slice s, double k = 0.9);
+
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/GzipByteFlow.cpp b/libs/tdlib/td/tdutils/td/utils/GzipByteFlow.cpp
new file mode 100644
index 0000000000..d225ef800e
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/GzipByteFlow.cpp
@@ -0,0 +1,70 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/GzipByteFlow.h"
+
+char disable_linker_warning_about_empty_file_gzipbyteflow_cpp TD_UNUSED;
+
+#if TD_HAVE_ZLIB
+#include "td/utils/logging.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+void GzipByteFlow::loop() {
+  while (true) {
+    if (gzip_.need_input()) {
+      auto slice = input_->prepare_read();
+      if (slice.empty()) {
+        if (!is_input_active_) {
+          gzip_.close_input();
+        } else {
+          break;
+        }
+      } else {
+        gzip_.set_input(input_->prepare_read());
+      }
+    }
+    if (gzip_.need_output()) {
+      auto slice = output_.prepare_append();
+      CHECK(!slice.empty());
+      gzip_.set_output(slice);
+    }
+    auto r_state = gzip_.run();
+    auto output_size = gzip_.flush_output();
+    if (output_size) {
+      uncommited_size_ += output_size;
+      total_output_size_ += output_size;
+      if (total_output_size_ > max_output_size_) {
+        return finish(Status::Error("Max output size limit exceeded"));
+      }
+      output_.confirm_append(output_size);
+    }
+
+    auto input_size = gzip_.flush_input();
+    if (input_size) {
+      input_->confirm_read(input_size);
+    }
+    if (r_state.is_error()) {
+      return finish(r_state.move_as_error());
+    }
+    auto state = r_state.ok();
+    if (state == Gzip::Done) {
+      on_output_updated();
+      return consume_input();
+    }
+  }
+  if (uncommited_size_ >= MIN_UPDATE_SIZE) {
+    uncommited_size_ = 0;
+    on_output_updated();
+  }
+}
+
+constexpr size_t GzipByteFlow::MIN_UPDATE_SIZE;
+
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/GzipByteFlow.h b/libs/tdlib/td/tdutils/td/utils/GzipByteFlow.h
new file mode 100644
index 0000000000..c7e07abd0a
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/GzipByteFlow.h
@@ -0,0 +1,48 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/ByteFlow.h"
+#include "td/utils/Gzip.h"
+
+#include <limits>
+
+namespace td {
+
+#if TD_HAVE_ZLIB
+class GzipByteFlow final : public ByteFlowBase {
+ public:
+  GzipByteFlow() = default;
+
+  explicit GzipByteFlow(Gzip::Mode mode) {
+    gzip_.init(mode).ensure();
+  }
+
+  void init_decode() {
+    gzip_.init_decode().ensure();
+  }
+
+  void init_encode() {
+    gzip_.init_encode().ensure();
+  }
+
+  void set_max_output_size(size_t max_output_size) {
+    max_output_size_ = max_output_size;
+  }
+
+  void loop() override;
+
+ private:
+  Gzip gzip_;
+  size_t uncommited_size_ = 0;
+  size_t total_output_size_ = 0;
+  size_t max_output_size_ = std::numeric_limits<size_t>::max();
+  static constexpr size_t MIN_UPDATE_SIZE = 1 << 14;
+};
+#endif
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/HazardPointers.h b/libs/tdlib/td/tdutils/td/utils/HazardPointers.h
new file mode 100644
index 0000000000..e13dc8022e
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/HazardPointers.h
@@ -0,0 +1,133 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+
+#include <array>
+#include <atomic>
+
+namespace td {
+
+template <class T, int MaxPointersN = 1>
+class HazardPointers {
+ public:
+  explicit HazardPointers(size_t threads_n) : threads_(threads_n) {
+    for (auto &data : threads_) {
+      for (auto &ptr : data.hazard) {
+        ptr = nullptr;
+      }
+    }
+  }
+  HazardPointers(const HazardPointers &other) = delete;
+  HazardPointers &operator=(const HazardPointers &other) = delete;
+  HazardPointers(HazardPointers &&other) = delete;
+  HazardPointers &operator=(HazardPointers &&other) = delete;
+
+  class Holder {
+   public:
+    T *protect(std::atomic<T *> &to_protect) {
+      return do_protect(hazard_ptr_, to_protect);
+    }
+    Holder(const Holder &other) = delete;
+    Holder &operator=(const Holder &other) = delete;
+    Holder(Holder &&other) = default;  // TODO
+    Holder &operator=(Holder &&other) = delete;
+    ~Holder() {
+      clear();
+    }
+    void clear() {
+      hazard_ptr_.store(nullptr, std::memory_order_release);
+    }
+
+   private:
+    friend class HazardPointers;
+    explicit Holder(std::atomic<T *> &ptr) : hazard_ptr_(ptr) {
+    }
+    std::atomic<T *> &hazard_ptr_;
+  };
+
+  Holder get_holder(size_t thread_id, size_t pos) {
+    return Holder(get_hazard_ptr(thread_id, pos));
+  }
+
+  void retire(size_t thread_id, T *ptr = nullptr) {
+    CHECK(thread_id < threads_.size());
+    auto &data = threads_[thread_id];
+    if (ptr) {
+      data.to_delete.push_back(std::unique_ptr<T>(ptr));
+    }
+    for (auto it = data.to_delete.begin(); it != data.to_delete.end();) {
+      if (!is_protected(it->get())) {
+        it->reset();
+        it = data.to_delete.erase(it);
+      } else {
+        ++it;
+      }
+    }
+  }
+
+  // old inteface
+  T *protect(size_t thread_id, size_t pos, std::atomic<T *> &ptr) {
+    return do_protect(get_hazard_ptr(thread_id, pos), ptr);
+  }
+  void clear(size_t thread_id, size_t pos) {
+    do_clear(get_hazard_ptr(thread_id, pos));
+  }
+
+  size_t to_delete_size_unsafe() const {
+    size_t res = 0;
+    for (auto &thread : threads_) {
+      res += thread.to_delete.size();
+    }
+    return res;
+  }
+
+ private:
+  struct ThreadData {
+    std::array<std::atomic<T *>, MaxPointersN> hazard;
+    char pad[TD_CONCURRENCY_PAD - sizeof(std::array<std::atomic<T *>, MaxPointersN>)];
+
+    // stupid gc
+    std::vector<std::unique_ptr<T>> to_delete;
+    char pad2[TD_CONCURRENCY_PAD - sizeof(std::vector<std::unique_ptr<T>>)];
+  };
+  std::vector<ThreadData> threads_;
+  char pad2[TD_CONCURRENCY_PAD - sizeof(std::vector<ThreadData>)];
+
+  static T *do_protect(std::atomic<T *> &hazard_ptr, std::atomic<T *> &to_protect) {
+    T *saved = nullptr;
+    T *to_save;
+    while ((to_save = to_protect.load()) != saved) {
+      hazard_ptr.store(to_save);
+      saved = to_save;
+    }
+    return saved;
+  }
+
+  static void do_clear(std::atomic<T *> &hazard_ptr) {
+    hazard_ptr.store(nullptr, std::memory_order_release);
+  }
+
+  bool is_protected(T *ptr) {
+    for (auto &thread : threads_) {
+      for (auto &hazard_ptr : thread.hazard) {
+        if (hazard_ptr.load() == ptr) {
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
+  std::atomic<T *> &get_hazard_ptr(size_t thread_id, size_t pos) {
+    return threads_[thread_id].hazard[pos];
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Heap.h b/libs/tdlib/td/tdutils/td/utils/Heap.h
new file mode 100644
index 0000000000..54ee391497
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Heap.h
@@ -0,0 +1,152 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+
+namespace td {
+
+struct HeapNode {
+  bool in_heap() const {
+    return pos_ != -1;
+  }
+  bool is_top() const {
+    return pos_ == 0;
+  }
+  void remove() {
+    pos_ = -1;
+  }
+  int pos_ = -1;
+};
+
+template <class KeyT, int K = 4>
+class KHeap {
+ public:
+  bool empty() const {
+    return array_.empty();
+  }
+  size_t size() const {
+    return array_.size();
+  }
+
+  KeyT top_key() const {
+    return array_[0].key_;
+  }
+
+  HeapNode *pop() {
+    CHECK(!empty());
+    HeapNode *result = array_[0].node_;
+    result->remove();
+    erase(0);
+    return result;
+  }
+
+  void insert(KeyT key, HeapNode *node) {
+    CHECK(!node->in_heap());
+    array_.push_back({key, node});
+    fix_up(static_cast<int>(array_.size()) - 1);
+  }
+
+  void fix(KeyT key, HeapNode *node) {
+    CHECK(node->in_heap());
+    int pos = node->pos_;
+    KeyT old_key = array_[pos].key_;
+    array_[pos].key_ = key;
+    if (key < old_key) {
+      fix_up(pos);
+    } else {
+      fix_down(pos);
+    }
+  }
+
+  void erase(HeapNode *node) {
+    CHECK(node->in_heap());
+    int pos = node->pos_;
+    node->remove();
+    erase(pos);
+  }
+
+  template <class F>
+  void for_each(F &f) const {
+    for (auto &it : array_) {
+      f(it.key_, it.node_);
+    }
+  }
+
+  void check() const {
+    for (size_t i = 0; i < array_.size(); i++) {
+      for (size_t j = i * K + 1; j < i * K + 1 + K && j < array_.size(); j++) {
+        CHECK(array_[i].key_ <= array_[j].key_) << i << " " << j;
+      }
+    }
+  }
+
+ private:
+  struct Item {
+    KeyT key_;
+    HeapNode *node_;
+  };
+  vector<Item> array_;
+
+  void fix_up(int pos) {
+    auto item = array_[pos];
+
+    while (pos) {
+      int parent_pos = (pos - 1) / K;
+      auto parent_item = array_[parent_pos];
+
+      if (parent_item.key_ < item.key_) {
+        break;
+      }
+
+      parent_item.node_->pos_ = pos;
+      array_[pos] = parent_item;
+      pos = parent_pos;
+    }
+
+    item.node_->pos_ = pos;
+    array_[pos] = item;
+  }
+
+  void fix_down(int pos) {
+    auto item = array_[pos];
+    while (true) {
+      int left_pos = pos * K + 1;
+      int right_pos = min(left_pos + K, static_cast<int>(array_.size()));
+      int next_pos = pos;
+      KeyT next_key = item.key_;
+      for (int i = left_pos; i < right_pos; i++) {
+        KeyT i_key = array_[i].key_;
+        if (i_key < next_key) {
+          next_key = i_key;
+          next_pos = i;
+        }
+      }
+      if (next_pos == pos) {
+        break;
+      }
+      array_[pos] = array_[next_pos];
+      array_[pos].node_->pos_ = pos;
+      pos = next_pos;
+    }
+
+    item.node_->pos_ = pos;
+    array_[pos] = item;
+  }
+
+  void erase(int pos) {
+    array_[pos] = array_.back();
+    array_.pop_back();
+    if (pos < static_cast<int>(array_.size())) {
+      fix_down(pos);
+      fix_up(pos);
+    }
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Hints.cpp b/libs/tdlib/td/tdutils/td/utils/Hints.cpp
new file mode 100644
index 0000000000..1e7449a668
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Hints.cpp
@@ -0,0 +1,191 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/Hints.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Slice.h"
+#include "td/utils/unicode.h"
+#include "td/utils/utf8.h"
+
+#include <algorithm>
+
+namespace td {
+
+vector<string> Hints::get_words(Slice name) {
+  bool in_word = false;
+  string word;
+  vector<string> words;
+  auto pos = name.ubegin();
+  auto end = name.uend();
+  while (pos != end) {
+    uint32 code;
+    pos = next_utf8_unsafe(pos, &code);
+
+    code = prepare_search_character(code);
+    if (code == 0) {
+      continue;
+    }
+    if (code == ' ') {
+      if (in_word) {
+        words.push_back(std::move(word));
+        word.clear();
+        in_word = false;
+      }
+    } else {
+      in_word = true;
+      append_utf8_character(word, code);
+    }
+  }
+  if (in_word) {
+    words.push_back(std::move(word));
+  }
+  std::sort(words.begin(), words.end());
+
+  size_t new_words_size = 0;
+  for (size_t i = 0; i != words.size(); i++) {
+    if (i == words.size() - 1 || !begins_with(words[i + 1], words[i])) {
+      if (i != new_words_size) {
+        words[new_words_size] = std::move(words[i]);
+      }
+      // LOG(ERROR) << "Get word " << words[new_words_size];
+      new_words_size++;
+    }
+  }
+  words.resize(new_words_size);
+  return words;
+}
+
+void Hints::add(KeyT key, Slice name) {
+  // LOG(ERROR) << "Add " << key << ": " << name;
+  auto it = key_to_name_.find(key);
+  if (it != key_to_name_.end()) {
+    if (it->second == name) {
+      return;
+    }
+    auto old_words = get_words(it->second);
+    for (auto &old_word : old_words) {
+      vector<KeyT> &keys = word_to_keys_[old_word];
+      auto key_it = std::find(keys.begin(), keys.end(), key);
+      CHECK(key_it != keys.end());
+      if (keys.size() == 1) {
+        word_to_keys_.erase(old_word);
+      } else {
+        CHECK(keys.size() > 1);
+        *key_it = keys.back();
+        keys.pop_back();
+      }
+    }
+  }
+  if (name.empty()) {
+    if (it != key_to_name_.end()) {
+      key_to_name_.erase(it);
+    }
+    key_to_rating_.erase(key);
+    return;
+  }
+  auto words = get_words(name);
+  for (auto &word : words) {
+    vector<KeyT> &keys = word_to_keys_[word];
+    CHECK(std::find(keys.begin(), keys.end(), key) == keys.end());
+    keys.push_back(key);
+  }
+  key_to_name_[key] = name.str();
+}
+
+void Hints::set_rating(KeyT key, RatingT rating) {
+  // LOG(ERROR) << "Set rating " << key << ": " << rating;
+  key_to_rating_[key] = rating;
+}
+
+vector<Hints::KeyT> Hints::search_word(const string &word) const {
+  // LOG(ERROR) << "Search word " << word;
+  vector<KeyT> results;
+  auto it = word_to_keys_.lower_bound(word);
+  while (it != word_to_keys_.end() && begins_with(it->first, word)) {
+    results.insert(results.end(), it->second.begin(), it->second.end());
+    ++it;
+  }
+
+  std::sort(results.begin(), results.end());
+  results.erase(std::unique(results.begin(), results.end()), results.end());
+  return results;
+}
+
+std::pair<size_t, vector<Hints::KeyT>> Hints::search(Slice query, int32 limit, bool return_all_for_empty_query) const {
+  // LOG(ERROR) << "Search " << query;
+  vector<KeyT> results;
+
+  if (limit < 0) {
+    return {key_to_name_.size(), std::move(results)};
+  }
+
+  auto words = get_words(query);
+  if (return_all_for_empty_query && words.empty()) {
+    results.reserve(key_to_name_.size());
+    for (auto &it : key_to_name_) {
+      results.push_back(it.first);
+    }
+  }
+
+  for (size_t i = 0; i < words.size(); i++) {
+    vector<KeyT> keys = search_word(words[i]);
+    if (i == 0) {
+      results = std::move(keys);
+      continue;
+    }
+
+    // now need to intersect two lists
+    size_t results_pos = 0;
+    size_t keys_pos = 0;
+    size_t new_results_size = 0;
+    while (results_pos != results.size() && keys_pos != keys.size()) {
+      if (results[results_pos] < keys[keys_pos]) {
+        results_pos++;
+      } else if (results[results_pos] > keys[keys_pos]) {
+        keys_pos++;
+      } else {
+        results[new_results_size++] = results[results_pos];
+        results_pos++;
+        keys_pos++;
+      }
+    }
+    results.resize(new_results_size);
+  }
+
+  auto total_size = results.size();
+  if (total_size < static_cast<size_t>(limit)) {
+    std::sort(results.begin(), results.end(), CompareByRating(key_to_rating_));
+  } else {
+    std::partial_sort(results.begin(), results.begin() + limit, results.end(), CompareByRating(key_to_rating_));
+    results.resize(limit);
+  }
+
+  return {total_size, std::move(results)};
+}
+
+bool Hints::has_key(KeyT key) const {
+  return key_to_name_.find(key) != key_to_name_.end();
+}
+
+string Hints::key_to_string(KeyT key) const {
+  auto it = key_to_name_.find(key);
+  if (it == key_to_name_.end()) {
+    return string();
+  }
+  return it->second;
+}
+
+std::pair<size_t, vector<Hints::KeyT>> Hints::search_empty(int32 limit) const {
+  return search(Slice(), limit, true);
+}
+
+size_t Hints::size() const {
+  return key_to_name_.size();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Hints.h b/libs/tdlib/td/tdutils/td/utils/Hints.h
new file mode 100644
index 0000000000..645896684a
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Hints.h
@@ -0,0 +1,76 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+
+#include <map>
+#include <unordered_map>
+#include <utility>
+
+namespace td {
+
+// TODO template KeyT
+class Hints {
+  using KeyT = int64;
+  using RatingT = int64;
+
+ public:
+  void add(KeyT key, Slice name);
+
+  void remove(KeyT key) {
+    add(key, "");
+  }
+
+  void set_rating(KeyT key, RatingT rating);
+
+  std::pair<size_t, vector<KeyT>> search(
+      Slice query, int32 limit,
+      bool return_all_for_empty_query = false) const;  // TODO sort by name instead of sort by rating
+
+  bool has_key(KeyT key) const;
+
+  string key_to_string(KeyT key) const;
+
+  std::pair<size_t, vector<KeyT>> search_empty(int32 limit) const;  // == search("", limit, true)
+
+  size_t size() const;
+
+ private:
+  std::map<string, vector<KeyT>> word_to_keys_;
+  std::unordered_map<KeyT, string> key_to_name_;
+  std::unordered_map<KeyT, RatingT> key_to_rating_;
+
+  static vector<string> get_words(Slice name);
+
+  vector<KeyT> search_word(const string &word) const;
+
+  class CompareByRating {
+    const std::unordered_map<KeyT, RatingT> &key_to_rating_;
+
+    RatingT get_rating(const KeyT &key) const {
+      auto it = key_to_rating_.find(key);
+      if (it == key_to_rating_.end()) {
+        return RatingT();
+      }
+      return it->second;
+    }
+
+   public:
+    explicit CompareByRating(const std::unordered_map<KeyT, RatingT> &key_to_rating) : key_to_rating_(key_to_rating) {
+    }
+
+    bool operator()(const KeyT &lhs, const KeyT &rhs) const {
+      auto lhs_rating = get_rating(lhs);
+      auto rhs_rating = get_rating(rhs);
+      return lhs_rating < rhs_rating || (lhs_rating == rhs_rating && lhs < rhs);
+    }
+  };
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/HttpUrl.cpp b/libs/tdlib/td/tdutils/td/utils/HttpUrl.cpp
new file mode 100644
index 0000000000..55b66f7b3a
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/HttpUrl.cpp
@@ -0,0 +1,189 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/HttpUrl.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Parser.h"
+
+namespace td {
+
+string HttpUrl::get_url() const {
+  string result;
+  switch (protocol_) {
+    case Protocol::HTTP:
+      result += "http://";
+      break;
+    case Protocol::HTTPS:
+      result += "https://";
+      break;
+    default:
+      UNREACHABLE();
+  }
+  if (!userinfo_.empty()) {
+    result += userinfo_;
+    result += '@';
+  }
+  if (is_ipv6) {
+    result += '[';
+  }
+  result += host_;
+  if (is_ipv6) {
+    result += ']';
+  }
+  if (specified_port_ > 0) {
+    result += ':';
+    result += to_string(specified_port_);
+  }
+  CHECK(!query_.empty() && query_[0] == '/');
+  result += query_;
+  return result;
+}
+
+Result<HttpUrl> parse_url(MutableSlice url, HttpUrl::Protocol default_protocol) {
+  // url == [https?://][userinfo@]host[:port]
+  Parser parser(url);
+  string protocol_str = to_lower(parser.read_till_nofail(':'));
+
+  HttpUrl::Protocol protocol;
+  if (parser.start_with("://")) {
+    parser.advance(3);
+    if (protocol_str == "http") {
+      protocol = HttpUrl::Protocol::HTTP;
+    } else if (protocol_str == "https") {
+      protocol = HttpUrl::Protocol::HTTPS;
+    } else {
+      return Status::Error("Unsupported URL protocol");
+    }
+  } else {
+    parser = Parser(url);
+    protocol = default_protocol;
+  }
+  Slice userinfo_host_port = parser.read_till_nofail("/?#");
+
+  int port = 0;
+  const char *colon = userinfo_host_port.end() - 1;
+  while (colon > userinfo_host_port.begin() && *colon != ':' && *colon != ']' && *colon != '@') {
+    colon--;
+  }
+  Slice userinfo_host;
+  if (colon > userinfo_host_port.begin() && *colon == ':') {
+    port = to_integer<int>(Slice(colon + 1, userinfo_host_port.end()));
+    userinfo_host = Slice(userinfo_host_port.begin(), colon);
+  } else {
+    userinfo_host = userinfo_host_port;
+  }
+  if (port < 0 || port > 65535) {
+    return Status::Error("Wrong port number specified in the URL");
+  }
+
+  auto at_pos = userinfo_host.rfind('@');
+  Slice userinfo = at_pos == static_cast<size_t>(-1) ? "" : userinfo_host.substr(0, at_pos);
+  Slice host = userinfo_host.substr(at_pos + 1);
+
+  bool is_ipv6 = false;
+  if (!host.empty() && host[0] == '[' && host.back() == ']') {
+    host.remove_prefix(1);
+    host.remove_suffix(1);
+    is_ipv6 = true;
+  }
+  if (host.empty()) {
+    return Status::Error("URL host is empty");
+  }
+
+  int specified_port = port;
+  if (port == 0) {
+    if (protocol == HttpUrl::Protocol::HTTP) {
+      port = 80;
+    } else {
+      CHECK(protocol == HttpUrl::Protocol::HTTPS);
+      port = 443;
+    }
+  }
+
+  Slice query = parser.read_all();
+  while (!query.empty() && is_space(query.back())) {
+    query.remove_suffix(1);
+  }
+  if (query.empty()) {
+    query = "/";
+  }
+  string query_str;
+  if (query[0] != '/') {
+    query_str = '/';
+  }
+  for (auto c : query) {
+    if (static_cast<unsigned char>(c) <= 0x20) {
+      query_str += '%';
+      query_str += "0123456789ABCDEF"[c / 16];
+      query_str += "0123456789ABCDEF"[c % 16];
+    } else {
+      query_str += c;
+    }
+  }
+
+  string host_str = to_lower(host);
+  for (size_t i = 0; i < host_str.size(); i++) {
+    char c = host_str[i];
+    if (('a' <= c && c <= 'z') || c == '.' || ('0' <= c && c <= '9') || c == '-' || c == '_' || c == '!' || c == '$' ||
+        c == ',' || c == '~' || c == '*' || c == '\'' || c == '(' || c == ')' || c == ';' || c == '&' || c == '+' ||
+        c == '=') {
+      // symbols allowed by RFC 7230 and RFC 3986
+      continue;
+    }
+    if (c == '%') {
+      c = host_str[++i];
+      if (('a' <= c && c <= 'f') || ('0' <= c && c <= '9')) {
+        c = host_str[++i];
+        if (('a' <= c && c <= 'f') || ('0' <= c && c <= '9')) {
+          // percent encoded symbol as allowed by RFC 7230 and RFC 3986
+          continue;
+        }
+      }
+    }
+    // all other symbols aren't allowed
+    unsigned char uc = static_cast<unsigned char>(c);
+    if (uc >= 128) {
+      // but we allow plain UTF-8 symbols
+      continue;
+    }
+    return Status::Error("Wrong URL host");
+  }
+
+  return HttpUrl{protocol, userinfo.str(), std::move(host_str), is_ipv6, specified_port, port, std::move(query_str)};
+}
+
+StringBuilder &operator<<(StringBuilder &sb, const HttpUrl &url) {
+  sb << tag("protocol", url.protocol_ == HttpUrl::Protocol::HTTP ? "HTTP" : "HTTPS") << tag("userinfo", url.userinfo_)
+     << tag("host", url.host_) << tag("port", url.port_) << tag("query", url.query_);
+  return sb;
+}
+
+string get_url_query_file_name(const string &query) {
+  Slice query_slice = query;
+  query_slice.truncate(query.find_first_of("?#"));
+
+  auto slash_pos = query_slice.rfind('/');
+  if (slash_pos < query_slice.size()) {
+    return query_slice.substr(slash_pos + 1).str();
+  }
+  return query_slice.str();
+}
+
+string get_url_file_name(const string &url) {
+  // TODO remove copy
+  string url_copy = url;
+  auto r_http_url = parse_url(url_copy);
+  if (r_http_url.is_error()) {
+    LOG(WARNING) << "Receive wrong URL \"" << url << '"';
+    return string();
+  }
+  return get_url_query_file_name(r_http_url.ok().query_);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/HttpUrl.h b/libs/tdlib/td/tdutils/td/utils/HttpUrl.h
new file mode 100644
index 0000000000..f7d1e4aaba
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/HttpUrl.h
@@ -0,0 +1,39 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+
+namespace td {
+
+class HttpUrl {
+ public:
+  enum class Protocol { HTTP, HTTPS } protocol_;
+  string userinfo_;
+  string host_;
+  bool is_ipv6;
+  int specified_port_;
+  int port_;
+  string query_;
+
+  string get_url() const;
+};
+
+// TODO Slice instead of MutableSlice
+Result<HttpUrl> parse_url(MutableSlice url,
+                          HttpUrl::Protocol default_protocol = HttpUrl::Protocol::HTTP) TD_WARN_UNUSED_RESULT;
+
+StringBuilder &operator<<(StringBuilder &sb, const HttpUrl &url);
+
+string get_url_query_file_name(const string &query);
+
+string get_url_file_name(const string &url);
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/JsonBuilder.cpp b/libs/tdlib/td/tdutils/td/utils/JsonBuilder.cpp
new file mode 100644
index 0000000000..eb654f43cd
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/JsonBuilder.cpp
@@ -0,0 +1,648 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/JsonBuilder.h"
+
+#include "td/utils/misc.h"
+#include "td/utils/ScopeGuard.h"
+
+#include <cstring>
+
+namespace td {
+StringBuilder &operator<<(StringBuilder &sb, const JsonRawString &val) {
+  sb << '"';
+  SCOPE_EXIT {
+    sb << '"';
+  };
+  auto *s = val.value_.begin();
+  auto len = val.value_.size();
+
+  for (size_t pos = 0; pos < len; pos++) {
+    auto ch = static_cast<unsigned char>(s[pos]);
+    switch (ch) {
+      case '"':
+        sb << '\\' << '"';
+        break;
+      case '\\':
+        sb << '\\' << '\\';
+        break;
+      case '\b':
+        sb << '\\' << 'b';
+        break;
+      case '\f':
+        sb << '\\' << 'f';
+        break;
+      case '\n':
+        sb << '\\' << 'n';
+        break;
+      case '\r':
+        sb << '\\' << 'r';
+        break;
+      case '\t':
+        sb << '\\' << 't';
+        break;
+      default:
+        if (ch <= 31) {
+          sb << JsonOneChar(s[pos]);
+          break;
+        }
+        sb << s[pos];
+        break;
+    }
+  }
+  return sb;
+}
+
+StringBuilder &operator<<(StringBuilder &sb, const JsonString &val) {
+  sb << '"';
+  SCOPE_EXIT {
+    sb << '"';
+  };
+  auto *s = val.str_.begin();
+  auto len = val.str_.size();
+
+  for (size_t pos = 0; pos < len; pos++) {
+    auto ch = static_cast<unsigned char>(s[pos]);
+    switch (ch) {
+      case '"':
+        sb << '\\' << '"';
+        break;
+      case '\\':
+        sb << '\\' << '\\';
+        break;
+      case '\b':
+        sb << '\\' << 'b';
+        break;
+      case '\f':
+        sb << '\\' << 'f';
+        break;
+      case '\n':
+        sb << '\\' << 'n';
+        break;
+      case '\r':
+        sb << '\\' << 'r';
+        break;
+      case '\t':
+        sb << '\\' << 't';
+        break;
+      default:
+        if (ch <= 31) {
+          sb << JsonOneChar(s[pos]);
+          break;
+        }
+        if (128 <= ch) {
+          int a = s[pos];
+          CHECK((a & 0x40) != 0);
+
+          CHECK(pos + 1 < len);
+          int b = s[++pos];
+          CHECK((b & 0xc0) == 0x80);
+          if ((a & 0x20) == 0) {
+            CHECK((a & 0x1e) > 0);
+            sb << JsonChar(((a & 0x1f) << 6) | (b & 0x3f));
+            break;
+          }
+
+          CHECK(pos + 1 < len);
+          int c = s[++pos];
+          CHECK((c & 0xc0) == 0x80);
+          if ((a & 0x10) == 0) {
+            CHECK(((a & 0x0f) | (b & 0x20)) > 0);
+            sb << JsonChar(((a & 0x0f) << 12) | ((b & 0x3f) << 6) | (c & 0x3f));
+            break;
+          }
+
+          CHECK(pos + 1 < len);
+          int d = s[++pos];
+          CHECK((d & 0xc0) == 0x80);
+          if ((a & 0x08) == 0) {
+            CHECK(((a & 0x07) | (b & 0x30)) > 0);
+            sb << JsonChar(((a & 0x07) << 18) | ((b & 0x3f) << 12) | ((c & 0x3f) << 6) | (d & 0x3f));
+            break;
+          }
+
+          UNREACHABLE();
+          break;
+        }
+        sb << s[pos];
+        break;
+    }
+  }
+  return sb;
+}
+Result<MutableSlice> json_string_decode(Parser &parser) {
+  if (!parser.try_skip('"')) {
+    return Status::Error("Opening '\"' expected");
+  }
+  auto *cur_src = parser.data().data();
+  auto *end_src = parser.data().end();
+  auto *end = cur_src;
+  while (end < end_src && end[0] != '"') {
+    if (end[0] == '\\') {
+      end++;
+    }
+    end++;
+  }
+  if (end >= end_src) {
+    return Status::Error("Closing '\"' not found");
+  }
+  parser.advance(end + 1 - cur_src);
+  end_src = end;
+
+  auto *cur_dest = cur_src;
+  auto *begin_dest = cur_src;
+
+  while (cur_src != end_src) {
+    auto *slash = static_cast<char *>(std::memchr(cur_src, '\\', end_src - cur_src));
+    if (slash == nullptr) {
+      slash = end_src;
+    }
+    std::memmove(cur_dest, cur_src, slash - cur_src);
+    cur_dest += slash - cur_src;
+    cur_src = slash;
+    if (cur_src != end_src) {
+      cur_src++;
+      if (cur_src == end_src) {
+        // TODO UNREACHABLE();
+        return Status::Error("Unexpected end of string");
+      }
+      switch (*cur_src) {
+        case '"':
+        case '\\':
+        case '/':
+          *cur_dest++ = *cur_src++;
+          break;
+        case 'b':
+          *cur_dest++ = '\b';
+          cur_src++;
+          break;
+        case 'f':
+          *cur_dest++ = '\f';
+          cur_src++;
+          break;
+        case 'n':
+          *cur_dest++ = '\n';
+          cur_src++;
+          break;
+        case 'r':
+          *cur_dest++ = '\r';
+          cur_src++;
+          break;
+        case 't':
+          *cur_dest++ = '\t';
+          cur_src++;
+          break;
+        case 'u': {
+          cur_src++;
+          if (cur_src + 4 > end_src) {
+            return Status::Error("\\u has less than 4 symbols");
+          }
+          int num = 0;
+          for (int i = 0; i < 4; i++, cur_src++) {
+            int d = hex_to_int(*cur_src);
+            if (d == 16) {
+              return Status::Error("Invalid \\u -- not hex digit");
+            }
+            num = num * 16 + d;
+          }
+          if (0xD7FF < num && num < 0xE000) {
+            if (cur_src + 6 <= end_src && cur_src[0] == '\\' && cur_src[1] == 'u') {
+              cur_src += 2;
+              int new_num = 0;
+              for (int i = 0; i < 4; i++, cur_src++) {
+                int d = hex_to_int(*cur_src);
+                if (d == 16) {
+                  return Status::Error("Invalid \\u -- not hex digit");
+                }
+                new_num = new_num * 16 + d;
+              }
+              if (0xD7FF < new_num && new_num < 0xE000) {
+                num = (((num & 0x3FF) << 10) | (new_num & 0x3FF)) + 0x10000;
+              } else {
+                cur_src -= 6;
+              }
+            }
+          }
+
+          if (num < 128) {
+            *cur_dest++ = static_cast<char>(num);
+          } else if (num < 0x800) {
+            *cur_dest++ = static_cast<char>(0xc0 + (num >> 6));
+            *cur_dest++ = static_cast<char>(0x80 + (num & 63));
+          } else if (num < 0xffff) {
+            *cur_dest++ = static_cast<char>(0xe0 + (num >> 12));
+            *cur_dest++ = static_cast<char>(0x80 + ((num >> 6) & 63));
+            *cur_dest++ = static_cast<char>(0x80 + (num & 63));
+          } else {
+            *cur_dest++ = static_cast<char>(0xf0 + (num >> 18));
+            *cur_dest++ = static_cast<char>(0x80 + ((num >> 12) & 63));
+            *cur_dest++ = static_cast<char>(0x80 + ((num >> 6) & 63));
+            *cur_dest++ = static_cast<char>(0x80 + (num & 63));
+          }
+          break;
+        }
+      }
+    }
+  }
+  CHECK(cur_dest <= end_src);
+  return MutableSlice(begin_dest, cur_dest);
+}
+
+Status json_string_skip(Parser &parser) {
+  if (!parser.try_skip('"')) {
+    return Status::Error("Opening '\"' expected");
+  }
+  auto *begin_src = parser.data().data();
+  auto *cur_src = begin_src;
+  auto *end_src = parser.data().end();
+  auto *end = cur_src;
+  while (end < end_src && *end != '"') {
+    if (*end == '\\') {
+      end++;
+    }
+    end++;
+  }
+  if (end >= end_src) {
+    return Status::Error("Closing '\"' not found");
+  }
+  parser.advance(end + 1 - cur_src);
+  end_src = end;
+
+  while (cur_src != end_src) {
+    auto *slash = static_cast<char *>(std::memchr(cur_src, '\\', end_src - cur_src));
+    if (slash == nullptr) {
+      slash = end_src;
+    }
+    cur_src = slash;
+    if (cur_src != end_src) {
+      cur_src++;
+      if (cur_src == end_src) {
+        // TODO UNREACHABLE();
+        return Status::Error("Unexpected end of string");
+      }
+      switch (*cur_src) {
+        case '"':
+        case '\\':
+        case '/':
+        case 'b':
+        case 'f':
+        case 'n':
+        case 'r':
+        case 't':
+          cur_src++;
+          break;
+        case 'u': {
+          cur_src++;
+          if (cur_src + 4 > end_src) {
+            return Status::Error("\\u has less than 4 symbols");
+          }
+          int num = 0;
+          for (int i = 0; i < 4; i++, cur_src++) {
+            int d = hex_to_int(*cur_src);
+            if (d == 16) {
+              return Status::Error("Invalid \\u -- not hex digit");
+            }
+            num = num * 16 + d;
+          }
+          if (0xD7FF < num && num < 0xE000) {
+            if (cur_src + 6 <= end_src && cur_src[0] == '\\' && cur_src[1] == 'u') {
+              cur_src += 2;
+              int new_num = 0;
+              for (int i = 0; i < 4; i++, cur_src++) {
+                int d = hex_to_int(*cur_src);
+                if (d == 16) {
+                  return Status::Error("Invalid \\u -- not hex digit");
+                }
+                new_num = new_num * 16 + d;
+              }
+              if (0xD7FF < new_num && new_num < 0xE000) {
+                // num = (((num & 0x3FF) << 10) | (new_num & 0x3FF)) + 0x10000;
+              } else {
+                cur_src -= 6;
+              }
+            }
+          }
+          break;
+        }
+      }
+    }
+  }
+  return Status::OK();
+}
+
+Result<JsonValue> do_json_decode(Parser &parser, int32 max_depth) {
+  if (max_depth < 0) {
+    return Status::Error("Too big object depth");
+  }
+
+  parser.skip_whitespaces();
+  switch (parser.peek_char()) {
+    case 'f':
+      if (parser.skip_start_with("false")) {
+        return JsonValue::create_boolean(false);
+      }
+      return Status::Error("Starts with 'f' -- false expected");
+    case 't':
+      if (parser.skip_start_with("true")) {
+        return JsonValue::create_boolean(true);
+      }
+      return Status::Error("Starts with 't' -- true expected");
+    case 'n':
+      if (parser.skip_start_with("null")) {
+        return JsonValue();
+      }
+      return Status::Error("Starts with 'n' -- null expected");
+    case '"': {
+      TRY_RESULT(slice, json_string_decode(parser));
+      return JsonValue::create_string(slice);
+    }
+    case '[': {
+      parser.skip('[');
+      parser.skip_whitespaces();
+      std::vector<JsonValue> res;
+      if (parser.try_skip(']')) {
+        return JsonValue::create_array(std::move(res));
+      }
+      while (true) {
+        if (parser.empty()) {
+          return Status::Error("Unexpected end");
+        }
+        TRY_RESULT(value, do_json_decode(parser, max_depth - 1));
+        res.emplace_back(std::move(value));
+
+        parser.skip_whitespaces();
+        if (parser.try_skip(']')) {
+          break;
+        }
+        if (parser.try_skip(',')) {
+          parser.skip_whitespaces();
+          continue;
+        }
+        return Status::Error("Unexpected symbol");
+      }
+      return JsonValue::create_array(std::move(res));
+    }
+    case '{': {
+      parser.skip('{');
+      parser.skip_whitespaces();
+      std::vector<std::pair<MutableSlice, JsonValue> > res;
+      if (parser.try_skip('}')) {
+        return JsonValue::make_object(std::move(res));
+      }
+      while (true) {
+        if (parser.empty()) {
+          return Status::Error("Unexpected end");
+        }
+        TRY_RESULT(key, json_string_decode(parser));
+        parser.skip_whitespaces();
+        if (!parser.try_skip(':')) {
+          return Status::Error("':' expected");
+        }
+        TRY_RESULT(value, do_json_decode(parser, max_depth - 1));
+        res.emplace_back(std::move(key), std::move(value));
+
+        parser.skip_whitespaces();
+        if (parser.try_skip('}')) {
+          break;
+        }
+        if (parser.try_skip(',')) {
+          parser.skip_whitespaces();
+          continue;
+        }
+        return Status::Error("Unexpected symbol");
+      }
+      return JsonValue::make_object(std::move(res));
+    }
+    case '-':
+    case '+':
+    case '.':
+    case '0':
+    case '1':
+    case '2':
+    case '3':
+    case '4':
+    case '5':
+    case '6':
+    case '7':
+    case '8':
+    case '9': {
+      auto num = parser.read_while(
+          [](char c) { return c == '-' || ('0' <= c && c <= '9') || c == 'e' || c == 'E' || c == '+' || c == '.'; });
+      return JsonValue::create_number(num);
+    }
+    case 0:
+      return Status::Error("Unexpected end");
+    default: {
+      char next = parser.peek_char();
+      if (0 < next && next < 127) {
+        return Status::Error(PSLICE() << "Unexpected symbol '" << parser.peek_char() << "'");
+      } else {
+        return Status::Error("Unexpected symbol");
+      }
+    }
+  }
+  UNREACHABLE();
+}
+
+Status do_json_skip(Parser &parser, int32 max_depth) {
+  if (max_depth < 0) {
+    return Status::Error("Too big object depth");
+  }
+
+  parser.skip_whitespaces();
+  switch (parser.peek_char()) {
+    case 'f':
+      if (parser.skip_start_with("false")) {
+        return Status::OK();
+      }
+      return Status::Error("Starts with 'f' -- false expected");
+    case 't':
+      if (parser.skip_start_with("true")) {
+        return Status::OK();
+      }
+      return Status::Error("Starts with 't' -- true expected");
+    case 'n':
+      if (parser.skip_start_with("null")) {
+        return Status::OK();
+      }
+      return Status::Error("Starts with 'n' -- null expected");
+    case '"': {
+      return json_string_skip(parser);
+    }
+    case '[': {
+      parser.skip('[');
+      parser.skip_whitespaces();
+      if (parser.try_skip(']')) {
+        return Status::OK();
+      }
+      while (true) {
+        if (parser.empty()) {
+          return Status::Error("Unexpected end");
+        }
+        TRY_STATUS(do_json_skip(parser, max_depth - 1));
+
+        parser.skip_whitespaces();
+        if (parser.try_skip(']')) {
+          break;
+        }
+        if (parser.try_skip(',')) {
+          parser.skip_whitespaces();
+          continue;
+        }
+        return Status::Error("Unexpected symbol");
+      }
+      return Status::OK();
+    }
+    case '{': {
+      parser.skip('{');
+      parser.skip_whitespaces();
+      if (parser.try_skip('}')) {
+        return Status::OK();
+      }
+      while (true) {
+        if (parser.empty()) {
+          return Status::Error("Unexpected end");
+        }
+        TRY_STATUS(json_string_skip(parser));
+        parser.skip_whitespaces();
+        if (!parser.try_skip(':')) {
+          return Status::Error("':' expected");
+        }
+        TRY_STATUS(do_json_skip(parser, max_depth - 1));
+
+        parser.skip_whitespaces();
+        if (parser.try_skip('}')) {
+          break;
+        }
+        if (parser.try_skip(',')) {
+          parser.skip_whitespaces();
+          continue;
+        }
+        return Status::Error("Unexpected symbol");
+      }
+      return Status::OK();
+    }
+    case '-':
+    case '+':
+    case '.':
+    case '0':
+    case '1':
+    case '2':
+    case '3':
+    case '4':
+    case '5':
+    case '6':
+    case '7':
+    case '8':
+    case '9': {
+      parser.read_while(
+          [](char c) { return c == '-' || ('0' <= c && c <= '9') || c == 'e' || c == 'E' || c == '+' || c == '.'; });
+      return Status::OK();
+    }
+    case 0:
+      return Status::Error("Unexpected end");
+    default: {
+      char next = parser.peek_char();
+      if (0 < next && next < 127) {
+        return Status::Error(PSLICE() << "Unexpected symbol '" << parser.peek_char() << "'");
+      } else {
+        return Status::Error("Unexpected symbol");
+      }
+    }
+  }
+  return Status::Error("Can't parse");
+}
+
+Slice JsonValue::get_type_name(Type type) {
+  switch (type) {
+    case Type::Null:
+      return Slice("Null");
+    case Type::Number:
+      return Slice("Number");
+    case Type::Boolean:
+      return Slice("Boolean");
+    case Type::String:
+      return Slice("String");
+    case Type::Array:
+      return Slice("Array");
+    case Type::Object:
+      return Slice("Object");
+    default:
+      UNREACHABLE();
+      return Slice("Unknown");
+  }
+}
+
+bool has_json_object_field(JsonObject &object, Slice name) {
+  for (auto &field_value : object) {
+    if (field_value.first == name) {
+      return true;
+    }
+  }
+  return false;
+}
+
+Result<JsonValue> get_json_object_field(JsonObject &object, Slice name, JsonValue::Type type, bool is_optional) {
+  for (auto &field_value : object) {
+    if (field_value.first == name) {
+      if (type != JsonValue::Type::Null && field_value.second.type() != type) {
+        return Status::Error(400, PSLICE()
+                                      << "Field \"" << name << "\" must be of type " << JsonValue::get_type_name(type));
+      }
+
+      return std::move(field_value.second);
+    }
+  }
+  if (!is_optional) {
+    return Status::Error(400, PSLICE() << "Can't find field \"" << name << "\"");
+  }
+  return JsonValue();
+}
+
+Result<bool> get_json_object_bool_field(JsonObject &object, Slice name, bool is_optional, bool default_value) {
+  TRY_RESULT(value, get_json_object_field(object, name, JsonValue::Type::Boolean, is_optional));
+  if (value.type() == JsonValue::Type::Null) {
+    return default_value;
+  }
+  return value.get_boolean();
+}
+
+Result<int32> get_json_object_int_field(JsonObject &object, Slice name, bool is_optional, int32 default_value) {
+  TRY_RESULT(value, get_json_object_field(object, name, JsonValue::Type::Number, is_optional));
+  if (value.type() == JsonValue::Type::Null) {
+    return default_value;
+  }
+  return to_integer_safe<int32>(value.get_number());
+}
+
+Result<double> get_json_object_double_field(JsonObject &object, Slice name, bool is_optional, double default_value) {
+  TRY_RESULT(value, get_json_object_field(object, name, JsonValue::Type::Number, is_optional));
+  if (value.type() == JsonValue::Type::Null) {
+    return default_value;
+  }
+  return to_double(value.get_number());
+}
+
+Result<string> get_json_object_string_field(JsonObject &object, Slice name, bool is_optional, string default_value) {
+  for (auto &field_value : object) {
+    if (field_value.first == name) {
+      if (field_value.second.type() == JsonValue::Type::String) {
+        return field_value.second.get_string().str();
+      }
+      if (field_value.second.type() == JsonValue::Type::Number) {
+        return field_value.second.get_number().str();
+      }
+
+      return Status::Error(400, PSLICE() << "Field \"" << name << "\" must be of type String");
+    }
+  }
+  if (is_optional) {
+    return default_value;
+  }
+  return Status::Error(400, PSLICE() << "Can't find field \"" << name << "\"");
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/JsonBuilder.h b/libs/tdlib/td/tdutils/td/utils/JsonBuilder.h
new file mode 100644
index 0000000000..735c4b29ec
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/JsonBuilder.h
@@ -0,0 +1,760 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/Parser.h"
+#include "td/utils/Slice.h"
+#include "td/utils/StackAllocator.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+
+#include <new>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+
+namespace td {
+
+template <class... Args>
+std::tuple<const Args &...> ctie(const Args &... args) TD_WARN_UNUSED_RESULT;
+
+template <class... Args>
+std::tuple<const Args &...> ctie(const Args &... args) {
+  return std::tie(args...);
+}
+
+class JsonTrue {
+ public:
+  friend StringBuilder &operator<<(StringBuilder &sb, const JsonTrue &val) {
+    return sb << "true";
+  }
+};
+
+class JsonFalse {
+ public:
+  friend StringBuilder &operator<<(StringBuilder &sb, const JsonFalse &val) {
+    return sb << "false";
+  }
+};
+
+class JsonNull {
+ public:
+  friend StringBuilder &operator<<(StringBuilder &sb, JsonNull val) {
+    return sb << "null";
+  }
+};
+
+class JsonBool {
+ public:
+  explicit JsonBool(bool value) : value_(value) {
+  }
+  friend StringBuilder &operator<<(StringBuilder &sb, const JsonBool &val) {
+    if (val.value_) {
+      return sb << JsonTrue();
+    } else {
+      return sb << JsonFalse();
+    }
+  }
+
+ private:
+  bool value_;
+};
+
+class JsonInt {
+ public:
+  explicit JsonInt(int32 value) : value_(value) {
+  }
+  friend StringBuilder &operator<<(StringBuilder &sb, const JsonInt &val) {
+    return sb << val.value_;
+  }
+
+ private:
+  int32 value_;
+};
+
+class JsonLong {
+ public:
+  explicit JsonLong(int64 value) : value_(value) {
+  }
+  friend StringBuilder &operator<<(StringBuilder &sb, const JsonLong &val) {
+    return sb << val.value_;
+  }
+
+ private:
+  int64 value_;
+};
+
+class JsonFloat {
+ public:
+  explicit JsonFloat(double value) : value_(value) {
+  }
+  friend StringBuilder &operator<<(StringBuilder &sb, const JsonFloat &val) {
+    return sb << val.value_;
+  }
+
+ private:
+  double value_;
+};
+
+class JsonOneChar {
+ public:
+  explicit JsonOneChar(unsigned int c) : c_(c) {
+  }
+
+  friend StringBuilder &operator<<(StringBuilder &sb, const JsonOneChar &val) {
+    auto c = val.c_;
+    return sb << '\\' << 'u' << "0123456789abcdef"[c >> 12] << "0123456789abcdef"[(c >> 8) & 15]
+              << "0123456789abcdef"[(c >> 4) & 15] << "0123456789abcdef"[c & 15];
+  }
+
+ private:
+  unsigned int c_;
+};
+
+class JsonChar {
+ public:
+  explicit JsonChar(unsigned int c) : c_(c) {
+  }
+  friend StringBuilder &operator<<(StringBuilder &sb, const JsonChar &val) {
+    auto c = val.c_;
+    if (c < 0x10000) {
+      if (0xD7FF < c && c < 0xE000) {
+        // UTF-8 correctness has already been checked
+        UNREACHABLE();
+      }
+      return sb << JsonOneChar(c);
+    } else if (c <= 0x10ffff) {
+      return sb << JsonOneChar(0xD7C0 + (c >> 10)) << JsonOneChar(0xDC00 + (c & 0x3FF));
+    } else {
+      // UTF-8 correctness has already been checked
+      UNREACHABLE();
+    }
+  }
+
+ private:
+  unsigned int c_;
+};
+
+class JsonRaw {
+ public:
+  explicit JsonRaw(Slice value) : value_(value) {
+  }
+  friend StringBuilder &operator<<(StringBuilder &sb, const JsonRaw &val) {
+    return sb << val.value_;
+  }
+
+ private:
+  Slice value_;
+};
+
+class JsonRawString {
+ public:
+  explicit JsonRawString(Slice value) : value_(value) {
+  }
+  friend StringBuilder &operator<<(StringBuilder &sb, const JsonRawString &val);
+
+ private:
+  Slice value_;
+};
+
+class JsonString {
+ public:
+  explicit JsonString(Slice str) : str_(str) {
+  }
+
+  friend StringBuilder &operator<<(StringBuilder &sb, const JsonString &val);
+
+ private:
+  Slice str_;
+};
+
+class JsonScope;
+class JsonValueScope;
+class JsonArrayScope;
+class JsonObjectScope;
+
+class JsonBuilder {
+ public:
+  explicit JsonBuilder(StringBuilder &&sb) : sb_(std::move(sb)) {
+  }
+  StringBuilder &string_builder() {
+    return sb_;
+  }
+  friend class JsonScope;
+  JsonValueScope enter_value() TD_WARN_UNUSED_RESULT;
+  JsonArrayScope enter_array() TD_WARN_UNUSED_RESULT;
+  JsonObjectScope enter_object() TD_WARN_UNUSED_RESULT;
+
+ private:
+  StringBuilder sb_;
+  JsonScope *scope_ = nullptr;
+};
+
+class Jsonable {};
+
+class JsonScope {
+ public:
+  explicit JsonScope(JsonBuilder *jb) : sb_(&jb->sb_), jb_(jb) {
+    save_scope_ = jb_->scope_;
+    jb_->scope_ = this;
+    CHECK(is_active());
+  }
+  JsonScope(const JsonScope &other) = delete;
+  JsonScope(JsonScope &&other) : sb_(other.sb_), jb_(other.jb_), save_scope_(other.save_scope_) {
+    other.jb_ = nullptr;
+  }
+  JsonScope &operator=(const JsonScope &) = delete;
+  JsonScope &operator=(JsonScope &&) = delete;
+  ~JsonScope() {
+    if (jb_) {
+      leave();
+    }
+  }
+  void leave() {
+    CHECK(is_active());
+    jb_->scope_ = save_scope_;
+  }
+
+ protected:
+  StringBuilder *sb_;
+
+  // For CHECK
+  JsonBuilder *jb_;
+  JsonScope *save_scope_;
+
+  bool is_active() const {
+    return jb_ && jb_->scope_ == this;
+  }
+
+  JsonScope &operator<<(JsonTrue x) {
+    *sb_ << x;
+    return *this;
+  }
+  JsonScope &operator<<(JsonFalse x) {
+    *sb_ << x;
+    return *this;
+  }
+  JsonScope &operator<<(JsonNull x) {
+    *sb_ << x;
+    return *this;
+  }
+  JsonScope &operator<<(const JsonBool &x) {
+    *sb_ << x;
+    return *this;
+  }
+  JsonScope &operator<<(const JsonInt &x) {
+    *sb_ << x;
+    return *this;
+  }
+  JsonScope &operator<<(const JsonLong &x) {
+    *sb_ << x;
+    return *this;
+  }
+  JsonScope &operator<<(const JsonFloat &x) {
+    *sb_ << x;
+    return *this;
+  }
+  JsonScope &operator<<(const JsonString &x) {
+    *sb_ << x;
+    return *this;
+  }
+  JsonScope &operator<<(const JsonRawString &x) {
+    *sb_ << x;
+    return *this;
+  }
+  JsonScope &operator<<(const JsonRaw &x) {
+    *sb_ << x;
+    return *this;
+  }
+  JsonScope &operator<<(bool x) {
+    return *this << JsonBool(x);
+  }
+  JsonScope &operator<<(int32 x) {
+    return *this << JsonInt(x);
+  }
+  JsonScope &operator<<(int64 x) {
+    return *this << JsonLong(x);
+  }
+  JsonScope &operator<<(double x) {
+    return *this << JsonFloat(x);
+  }
+  template <class T>
+  JsonScope &operator<<(const T *x);  // not implemented
+  template <size_t N>
+  JsonScope &operator<<(const char (&x)[N]) {
+    return *this << JsonString(Slice(x));
+  }
+  JsonScope &operator<<(const char *x) {
+    return *this << JsonString(Slice(x));
+  }
+  JsonScope &operator<<(const string &x) {
+    return *this << JsonString(Slice(x));
+  }
+  JsonScope &operator<<(Slice x) {
+    return *this << JsonString(x);
+  }
+};
+
+class JsonValueScope : public JsonScope {
+ public:
+  using JsonScope::JsonScope;
+  template <class T>
+  std::enable_if_t<std::is_base_of<Jsonable, typename std::decay<T>::type>::value, JsonValueScope &> operator<<(
+      const T &x) {
+    x.store(this);
+    return *this;
+  }
+  template <class T>
+  std::enable_if_t<!std::is_base_of<Jsonable, typename std::decay<T>::type>::value, JsonValueScope &> operator<<(
+      const T &x) {
+    CHECK(!was_);
+    was_ = true;
+    JsonScope::operator<<(x);
+    return *this;
+  }
+
+  JsonArrayScope enter_array() TD_WARN_UNUSED_RESULT;
+  JsonObjectScope enter_object() TD_WARN_UNUSED_RESULT;
+
+ private:
+  bool was_ = false;
+};
+
+class JsonArrayScope : public JsonScope {
+ public:
+  explicit JsonArrayScope(JsonBuilder *jb) : JsonScope(jb) {
+    *sb_ << "[";
+  }
+  JsonArrayScope(JsonArrayScope &&other) = default;
+  ~JsonArrayScope() {
+    if (jb_) {
+      leave();
+    }
+  }
+  void leave() {
+    *sb_ << "]";
+  }
+  template <class T>
+  JsonArrayScope &operator<<(const T &x) {
+    enter_value() << x;
+    return *this;
+  }
+  JsonValueScope enter_value() {
+    CHECK(is_active());
+    if (is_first_) {
+      *sb_ << ",";
+    } else {
+      is_first_ = true;
+    }
+    return jb_->enter_value();
+  }
+
+ private:
+  bool is_first_ = false;
+};
+
+class JsonObjectScope : public JsonScope {
+ public:
+  explicit JsonObjectScope(JsonBuilder *jb) : JsonScope(jb) {
+    *sb_ << "{";
+  }
+  JsonObjectScope(JsonObjectScope &&other) = default;
+  ~JsonObjectScope() {
+    if (jb_) {
+      leave();
+    }
+  }
+  void leave() {
+    *sb_ << "}";
+  }
+  template <class S, class T>
+  JsonObjectScope &operator<<(std::tuple<S, T> key_value) {
+    return *this << std::pair<S, T>(std::get<0>(key_value), std::get<1>(key_value));
+  }
+  template <class S, class T>
+  JsonObjectScope &operator<<(std::pair<S, T> key_value) {
+    CHECK(is_active());
+    if (is_first_) {
+      *sb_ << ",";
+    } else {
+      is_first_ = true;
+    }
+    jb_->enter_value() << key_value.first;
+    *sb_ << ":";
+    jb_->enter_value() << key_value.second;
+    return *this;
+  }
+  JsonObjectScope &operator<<(const JsonRaw &key_value) {
+    CHECK(is_active());
+    is_first_ = true;
+    jb_->enter_value() << key_value;
+    return *this;
+  }
+
+ private:
+  bool is_first_ = false;
+};
+
+inline JsonArrayScope JsonValueScope::enter_array() {
+  CHECK(!was_);
+  was_ = true;
+  return JsonArrayScope(jb_);
+}
+inline JsonObjectScope JsonValueScope::enter_object() {
+  CHECK(!was_);
+  was_ = true;
+  return JsonObjectScope(jb_);
+}
+inline JsonValueScope JsonBuilder::enter_value() {
+  return JsonValueScope(this);
+}
+inline JsonObjectScope JsonBuilder::enter_object() {
+  return JsonObjectScope(this);
+}
+inline JsonArrayScope JsonBuilder::enter_array() {
+  return JsonArrayScope(this);
+}
+
+class JsonValue;
+
+using JsonObject = vector<std::pair<MutableSlice, JsonValue>>;
+using JsonArray = vector<JsonValue>;
+
+class JsonValue : public Jsonable {
+ public:
+  enum class Type { Null, Number, Boolean, String, Array, Object };
+
+  static Slice get_type_name(Type type);
+
+  JsonValue() {
+  }
+  ~JsonValue() {
+    destroy();
+  }
+  JsonValue(JsonValue &&other) : JsonValue() {
+    init(std::move(other));
+  }
+  JsonValue &operator=(JsonValue &&other) {
+    if (&other == this) {
+      return *this;
+    }
+    destroy();
+    init(std::move(other));
+    return *this;
+  }
+  JsonValue(const JsonValue &other) = delete;
+  JsonValue &operator=(const JsonValue &other) = delete;
+
+  Type type() const {
+    return type_;
+  }
+
+  MutableSlice &get_string() {
+    CHECK(type_ == Type::String);
+    return string_;
+  }
+  const MutableSlice &get_string() const {
+    CHECK(type_ == Type::String);
+    return string_;
+  }
+  bool &get_boolean() {
+    CHECK(type_ == Type::Boolean);
+    return boolean_;
+  }
+  const bool &get_boolean() const {
+    CHECK(type_ == Type::Boolean);
+    return boolean_;
+  }
+
+  MutableSlice &get_number() {
+    CHECK(type_ == Type::Number);
+    return number_;
+  }
+  const MutableSlice &get_number() const {
+    CHECK(type_ == Type::Number);
+    return number_;
+  }
+
+  JsonArray &get_array() {
+    CHECK(type_ == Type::Array);
+    return array_;
+  }
+  const JsonArray &get_array() const {
+    CHECK(type_ == Type::Array);
+    return array_;
+  }
+
+  JsonObject &get_object() {
+    CHECK(type_ == Type::Object);
+    return object_;
+  }
+  const JsonObject &get_object() const {
+    CHECK(type_ == Type::Object);
+    return object_;
+  }
+
+  static JsonValue create_boolean(bool val) {
+    JsonValue res;
+    res.init_boolean(val);
+    return res;
+  }
+
+  static JsonValue create_number(MutableSlice number) {
+    JsonValue res;
+    res.init_number(number);
+    return res;
+  }
+
+  static JsonValue create_string(MutableSlice str) {
+    JsonValue res;
+    res.init_string(str);
+    return res;
+  }
+
+  static JsonValue create_array(JsonArray v) {
+    JsonValue res;
+    res.init_array(std::move(v));
+    return res;
+  }
+
+  static JsonValue make_object(JsonObject c) {
+    JsonValue res;
+    res.init_object(std::move(c));
+    return res;
+  }
+
+  void store(JsonValueScope *scope) const {
+    switch (type_) {
+      case Type::Null:
+        *scope << JsonRaw("null");
+        break;
+      case Type::Boolean:
+        if (get_boolean()) {
+          *scope << JsonRaw("true");
+        } else {
+          *scope << JsonRaw("false");
+        }
+        break;
+      case Type::Number:
+        *scope << JsonRaw(get_number());
+        break;
+      case Type::String:
+        *scope << JsonString(get_string());
+        break;
+      case Type::Array: {
+        auto arr = scope->enter_array();
+        for (auto &val : get_array()) {
+          arr << val;
+        }
+        break;
+      }
+      case Type::Object: {
+        auto object = scope->enter_object();
+        for (auto &key_value : get_object()) {
+          object << ctie(JsonString(key_value.first), key_value.second);
+        }
+        break;
+      }
+    }
+  };
+
+ private:
+  Type type_{Type::Null};
+  union {
+    MutableSlice number_;
+    bool boolean_;
+    MutableSlice string_;
+    JsonArray array_;
+    JsonObject object_;
+  };
+
+  void init_null() {
+    type_ = Type::Null;
+  }
+  void init_number(MutableSlice number) {
+    type_ = Type::Number;
+    new (&number_) MutableSlice(number);
+  }
+  void init_boolean(bool boolean) {
+    type_ = Type::Boolean;
+    boolean_ = boolean;
+  }
+  void init_string(MutableSlice slice) {
+    type_ = Type::String;
+    new (&string_) MutableSlice(slice);
+  }
+  void init_array(JsonArray array) {
+    type_ = Type::Array;
+    new (&array_) JsonArray(std::move(array));
+  }
+  void init_object(JsonObject object) {
+    type_ = Type::Object;
+    new (&object_) JsonObject(std::move(object));
+  }
+
+  void init(JsonValue &&other) {
+    switch (other.type_) {
+      case Type::Null:
+        break;
+      case Type::Number:
+        init_number(other.number_);
+        break;
+      case Type::Boolean:
+        init_boolean(other.boolean_);
+        break;
+      case Type::String:
+        init_string(other.string_);
+        break;
+      case Type::Array:
+        init_array(std::move(other.array_));
+        break;
+      case Type::Object:
+        init_object(std::move(other.object_));
+        break;
+    }
+    other.destroy();
+  }
+
+  void destroy() {
+    switch (type_) {
+      case Type::Null:
+      case Type::Boolean:
+        break;
+      case Type::Number:
+        number_.~MutableSlice();
+        break;
+      case Type::String:
+        string_.~MutableSlice();
+        break;
+      case Type::Array:
+        array_.~vector<JsonValue>();
+        break;
+      case Type::Object:
+        object_.~vector<std::pair<MutableSlice, JsonValue>>();
+        break;
+    }
+    type_ = Type::Null;
+  }
+};
+
+inline StringBuilder &operator<<(StringBuilder &sb, JsonValue::Type type) {
+  switch (type) {
+    case JsonValue::Type::Object:
+      return sb << "JsonObject";
+    case JsonValue::Type::Boolean:
+      return sb << "JsonBoolean";
+    case JsonValue::Type::Null:
+      return sb << "JsonNull";
+    case JsonValue::Type::Number:
+      return sb << "JsonNumber";
+    case JsonValue::Type::Array:
+      return sb << "JsonArray";
+    case JsonValue::Type::String:
+      return sb << "JsonString";
+    default:
+      UNREACHABLE();
+      return sb;
+  }
+}
+
+class VirtuallyJsonable : public Jsonable {
+ public:
+  virtual void store(JsonValueScope *scope) const = 0;
+  VirtuallyJsonable() = default;
+  VirtuallyJsonable(const VirtuallyJsonable &) = delete;
+  VirtuallyJsonable &operator=(const VirtuallyJsonable &) = delete;
+  VirtuallyJsonable(VirtuallyJsonable &&) = default;
+  VirtuallyJsonable &operator=(VirtuallyJsonable &&) = default;
+  virtual ~VirtuallyJsonable() = default;
+};
+
+class VirtuallyJsonableInt : public VirtuallyJsonable {
+ public:
+  explicit VirtuallyJsonableInt(int32 value) : value_(value) {
+  }
+  void store(JsonValueScope *scope) const override {
+    *scope << JsonInt(value_);
+  }
+
+ private:
+  int32 value_;
+};
+
+class VirtuallyJsonableLong : public VirtuallyJsonable {
+ public:
+  explicit VirtuallyJsonableLong(int64 value) : value_(value) {
+  }
+  void store(JsonValueScope *scope) const override {
+    *scope << JsonLong(value_);
+  }
+
+ private:
+  int64 value_;
+};
+
+class VirtuallyJsonableString : public VirtuallyJsonable {
+ public:
+  explicit VirtuallyJsonableString(Slice value) : value_(value) {
+  }
+  void store(JsonValueScope *scope) const override {
+    *scope << JsonString(value_);
+  }
+
+ private:
+  Slice value_;
+};
+
+Result<MutableSlice> json_string_decode(Parser &parser) TD_WARN_UNUSED_RESULT;
+Status json_string_skip(Parser &parser) TD_WARN_UNUSED_RESULT;
+
+Result<JsonValue> do_json_decode(Parser &parser, int32 max_depth) TD_WARN_UNUSED_RESULT;
+Status do_json_skip(Parser &parser, int32 max_depth) TD_WARN_UNUSED_RESULT;
+
+inline Result<JsonValue> json_decode(MutableSlice from) {
+  Parser parser(from);
+  const int32 DEFAULT_MAX_DEPTH = 100;
+  auto result = do_json_decode(parser, DEFAULT_MAX_DEPTH);
+  if (result.is_ok()) {
+    parser.skip_whitespaces();
+    if (!parser.empty()) {
+      return Status::Error("Expected string end");
+    }
+  }
+  return result;
+}
+
+template <class StrT, class ValT>
+StrT json_encode(const ValT &val) {
+  auto buf_len = 1 << 19;
+  auto buf = StackAllocator::alloc(buf_len);
+  JsonBuilder jb(StringBuilder(buf.as_slice()));
+  jb.enter_value() << val;
+  LOG_IF(ERROR, jb.string_builder().is_error()) << "Json buffer overflow";
+  auto slice = jb.string_builder().as_cslice();
+  return StrT(slice.begin(), slice.size());
+}
+
+bool has_json_object_field(JsonObject &object, Slice name);
+
+Result<JsonValue> get_json_object_field(JsonObject &object, Slice name, JsonValue::Type type,
+                                        bool is_optional = true) TD_WARN_UNUSED_RESULT;
+
+Result<bool> get_json_object_bool_field(JsonObject &object, Slice name, bool is_optional = true,
+                                        bool default_value = false) TD_WARN_UNUSED_RESULT;
+
+Result<int32> get_json_object_int_field(JsonObject &object, Slice name, bool is_optional = true,
+                                        int32 default_value = 0) TD_WARN_UNUSED_RESULT;
+
+Result<double> get_json_object_double_field(JsonObject &object, Slice name, bool is_optional = true,
+                                            double default_value = 0.0) TD_WARN_UNUSED_RESULT;
+
+Result<string> get_json_object_string_field(JsonObject &object, Slice name, bool is_optional = true,
+                                            string default_value = "") TD_WARN_UNUSED_RESULT;
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/List.h b/libs/tdlib/td/tdutils/td/utils/List.h
new file mode 100644
index 0000000000..1606c44d2b
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/List.h
@@ -0,0 +1,92 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/logging.h"
+
+namespace td {
+
+struct ListNode {
+  ListNode *next;
+  ListNode *prev;
+  ListNode() {
+    clear();
+  }
+
+  ~ListNode() {
+    remove();
+  }
+
+  ListNode(const ListNode &) = delete;
+  ListNode &operator=(const ListNode &) = delete;
+
+  ListNode(ListNode &&other) {
+    if (other.empty()) {
+      clear();
+    } else {
+      ListNode *head = other.prev;
+      other.remove();
+      head->put(this);
+    }
+  }
+
+  ListNode &operator=(ListNode &&other) {
+    this->remove();
+
+    if (!other.empty()) {
+      ListNode *head = other.prev;
+      other.remove();
+      head->put(this);
+    }
+
+    return *this;
+  }
+
+  void connect(ListNode *to) {
+    CHECK(to != nullptr);
+    next = to;
+    to->prev = this;
+  }
+
+  void remove() {
+    prev->connect(next);
+    clear();
+  }
+
+  void put(ListNode *other) {
+    other->connect(next);
+    this->connect(other);
+  }
+
+  void put_back(ListNode *other) {
+    prev->connect(other);
+    other->connect(this);
+  }
+
+  ListNode *get() {
+    ListNode *result = prev;
+    if (result == this) {
+      return nullptr;
+    }
+    result->prev->connect(this);
+    result->clear();
+    // this->connect(result->next);
+    return result;
+  }
+
+  bool empty() const {
+    return next == this;
+  }
+
+ private:
+  void clear() {
+    next = this;
+    prev = this;
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/MemoryLog.h b/libs/tdlib/td/tdutils/td/utils/MemoryLog.h
new file mode 100644
index 0000000000..aa125df2f7
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/MemoryLog.h
@@ -0,0 +1,83 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+
+#include <atomic>
+#include <cstdio>
+#include <cstring>
+
+namespace td {
+
+template <int buffer_size = 32 * (1 << 10)>
+class MemoryLog : public LogInterface {
+  static constexpr size_t MAX_OUTPUT_SIZE = buffer_size / 16 < (8 << 10) ? buffer_size / 16 : (8 << 10);
+
+ public:
+  MemoryLog() {
+    std::memset(buffer_, ' ', sizeof(buffer_));
+  }
+
+  void append(CSlice new_slice, int log_level) override {
+    Slice slice = new_slice;
+    slice.truncate(MAX_OUTPUT_SIZE);
+    while (!slice.empty() && slice.back() == '\n') {
+      slice.remove_suffix(1);
+    }
+    size_t slice_size = slice.size();
+    CHECK(slice_size * 3 < buffer_size);
+    size_t pad_size = ((slice_size + 15) & ~15) - slice_size;
+    constexpr size_t magic_size = 16;
+    uint32 total_size = static_cast<uint32>(slice_size + pad_size + magic_size);
+    uint32 real_pos = pos_.fetch_add(total_size, std::memory_order_relaxed);
+    CHECK((total_size & 15) == 0);
+
+    uint32 start_pos = real_pos & (buffer_size - 1);
+    uint32 end_pos = start_pos + total_size;
+    if (likely(end_pos <= buffer_size)) {
+      std::memcpy(&buffer_[start_pos + magic_size], slice.data(), slice_size);
+      std::memcpy(&buffer_[start_pos + magic_size + slice_size], "                     ", pad_size);
+    } else {
+      size_t first = buffer_size - start_pos - magic_size;
+      size_t second = slice_size - first;
+      std::memcpy(&buffer_[start_pos + magic_size], slice.data(), first);
+      std::memcpy(&buffer_[0], slice.data() + first, second);
+      std::memcpy(&buffer_[second], "                            ", pad_size);
+    }
+
+    CHECK((start_pos & 15) == 0);
+    CHECK(start_pos <= buffer_size - magic_size);
+    buffer_[start_pos] = '\n';
+    size_t printed = std::snprintf(&buffer_[start_pos + 1], magic_size - 1, "LOG:%08x: ", real_pos);
+    CHECK(printed == magic_size - 2);
+    buffer_[start_pos + magic_size - 1] = ' ';
+
+    if (log_level == VERBOSITY_NAME(FATAL)) {
+      process_fatal_error(new_slice);
+    }
+  }
+
+  void rotate() override {
+  }
+
+  Slice get_buffer() const {
+    return Slice(buffer_, sizeof(buffer_));
+  }
+
+  size_t get_pos() const {
+    return pos_ & (buffer_size - 1);
+  }
+
+ private:
+  char buffer_[buffer_size];
+  std::atomic<uint32> pos_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/MimeType.cpp b/libs/tdlib/td/tdutils/td/utils/MimeType.cpp
new file mode 100644
index 0000000000..75c4fe34b5
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/MimeType.cpp
@@ -0,0 +1,44 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/MimeType.h"
+
+#include "td/utils/logging.h"
+
+const char *extension_to_mime_type(const char *extension, size_t extension_len);  // auto-generated
+const char *mime_type_to_extension(const char *mime_type, size_t mime_type_len);  // auto-generated
+
+namespace td {
+
+string MimeType::to_extension(Slice mime_type, Slice default_value) {
+  if (mime_type.empty()) {
+    return default_value.str();
+  }
+
+  const char *result = ::mime_type_to_extension(mime_type.data(), mime_type.size());
+  if (result != nullptr) {
+    return result;
+  }
+
+  LOG(INFO) << "Unknown file MIME type " << mime_type;
+  return default_value.str();
+}
+
+string MimeType::from_extension(Slice extension, Slice default_value) {
+  if (extension.empty()) {
+    return default_value.str();
+  }
+
+  const char *result = ::extension_to_mime_type(extension.data(), extension.size());
+  if (result != nullptr) {
+    return result;
+  }
+
+  LOG(INFO) << "Unknown file extension " << extension;
+  return default_value.str();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/MimeType.h b/libs/tdlib/td/tdutils/td/utils/MimeType.h
new file mode 100644
index 0000000000..11210ceb30
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/MimeType.h
@@ -0,0 +1,20 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+
+namespace td {
+
+class MimeType {
+ public:
+  static string to_extension(Slice mime_type, Slice default_value = Slice());
+  static string from_extension(Slice extension, Slice default_value = Slice());
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/MovableValue.h b/libs/tdlib/td/tdutils/td/utils/MovableValue.h
new file mode 100644
index 0000000000..939bf51f28
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/MovableValue.h
@@ -0,0 +1,40 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+namespace td {
+
+template <class T, T empty_val = T()>
+class MovableValue {
+ public:
+  MovableValue() = default;
+  MovableValue(T val) : val_(val) {
+  }
+  MovableValue(MovableValue &&other) : val_(other.val_) {
+    other.clear();
+  }
+  MovableValue &operator=(MovableValue &&other) {
+    val_ = other.val_;
+    other.clear();
+    return *this;
+  }
+  MovableValue(const MovableValue &) = delete;
+  MovableValue &operator=(const MovableValue &) = delete;
+  ~MovableValue() = default;
+
+  void clear() {
+    val_ = empty_val;
+  }
+  const T &get() const {
+    return val_;
+  }
+
+ private:
+  T val_ = empty_val;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/MpmcQueue.h b/libs/tdlib/td/tdutils/td/utils/MpmcQueue.h
new file mode 100644
index 0000000000..ae65554b72
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/MpmcQueue.h
@@ -0,0 +1,449 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+// MPMC queue
+// Simple semaphore protected implementation
+// To close queue, one should send as much sentinel elements as there are readers.
+// Once there are no readers and writers, one may easily destroy queue
+
+#include "td/utils/format.h"
+#include "td/utils/HazardPointers.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/thread.h"
+#include "td/utils/ScopeGuard.h"
+
+#include <array>
+#include <atomic>
+
+namespace td {
+
+namespace detail {
+struct MpmcStat {
+  void alloc_ok(size_t thread_id) {
+    s(thread_id).alloc_ok_cnt++;
+  }
+  void alloc_error(size_t thread_id) {
+    s(thread_id).alloc_error_cnt++;
+  }
+  void push_loop_error(size_t thread_id) {
+    s(thread_id).push_loop_error_cnt++;
+  }
+  void push_loop_ok(size_t thread_id) {
+    s(thread_id).push_loop_ok_cnt++;
+  }
+  void dump() {
+    int alloc_ok_cnt = 0;
+    int alloc_error_cnt = 0;
+    int push_loop_error_cnt = 0;
+    int push_loop_ok_cnt = 0;
+    for (auto &d : arr) {
+      alloc_ok_cnt += d.alloc_ok_cnt;
+      alloc_error_cnt += d.alloc_error_cnt;
+      push_loop_error_cnt += d.push_loop_error_cnt;
+      push_loop_ok_cnt += d.push_loop_ok_cnt;
+    }
+    LOG(ERROR) << tag("alloc_ok_cnt", alloc_ok_cnt) << tag("alloc_error_cnt", alloc_error_cnt)
+               << tag("push_loop_error_cnt", push_loop_error_cnt) << tag("push_loop_ok_cnt", push_loop_ok_cnt);
+  }
+
+ private:
+  struct ThreadStat {
+    int alloc_ok_cnt{0};
+    int alloc_error_cnt{0};
+    int push_loop_ok_cnt{0};
+    int push_loop_error_cnt{0};
+    char pad[TD_CONCURRENCY_PAD - sizeof(int) * 4];
+  };
+  std::array<ThreadStat, 1024> arr;
+  ThreadStat &s(size_t thread_id) {
+    return arr[thread_id];
+  }
+};
+}  // namespace detail
+//detail::MpmcStat stat_;
+
+template <class T>
+class OneValue {
+ public:
+  bool set_value(T &value) {
+    value_ = std::move(value);
+    int state = Empty;
+    if (state_.compare_exchange_strong(state, Value, std::memory_order_acq_rel)) {
+      return true;
+    }
+    value = std::move(value_);
+    return false;
+  }
+  bool get_value(T &value) {
+    auto old_state = state_.exchange(Taken, std::memory_order_acq_rel);
+    if (old_state == Value) {
+      value = std::move(value_);
+      return true;
+    }
+    return false;
+  }
+  void reset() {
+    state_ = Empty;
+    value_ = T();
+  }
+
+ private:
+  enum Type : int { Empty = 0, Taken, Value };
+  std::atomic<int> state_{Empty};
+  T value_;
+};
+
+template <class T>
+class OneValue<T *> {
+ public:
+  bool set_value(T *value) {
+    T *was = nullptr;
+    return state_.compare_exchange_strong(was, value, std::memory_order_acq_rel);
+  }
+  bool get_value(T *&value) {
+    value = state_.exchange(Taken(), std::memory_order_acq_rel);
+    return value != nullptr;
+  }
+  void reset() {
+    state_ = nullptr;
+  }
+  OneValue() {
+  }
+
+ private:
+  std::atomic<T *> state_{nullptr};
+  T *Taken() {
+    static T xxx;
+    return &xxx;
+  }
+};
+
+template <class T>
+class MpmcQueueBlock {
+ public:
+  explicit MpmcQueueBlock(size_t size) : nodes_(size) {
+  }
+  enum class PopStatus { Ok, Empty, Closed };
+
+  //blocking pop
+  //returns Ok or Closed
+  PopStatus pop(T &value) {
+    while (true) {
+      auto read_pos = read_pos_.fetch_add(1, std::memory_order_relaxed);
+      if (read_pos >= nodes_.size()) {
+        return PopStatus::Closed;
+      }
+      //TODO blocking get_value
+      if (nodes_[static_cast<size_t>(read_pos)].one_value.get_value(value)) {
+        return PopStatus::Ok;
+      }
+    }
+  }
+
+  //nonblocking pop
+  //returns Ok, Empty or Closed
+  PopStatus try_pop(T &value) {
+    while (true) {
+      auto read_pos = read_pos_.fetch_add(1, std::memory_order_relaxed);
+      if (read_pos >= nodes_.size()) {
+        return PopStatus::Closed;
+      }
+      if (nodes_[static_cast<size_t>(read_pos)].one_value.get_value(value)) {
+        return PopStatus::Ok;
+      }
+      auto write_pos = write_pos_.load(std::memory_order_relaxed);
+      if (write_pos <= read_pos + 1) {
+        return PopStatus::Empty;
+      }
+    }
+  }
+
+  enum class PushStatus { Ok, Closed };
+  PushStatus push(T &value) {
+    while (true) {
+      auto write_pos = write_pos_.fetch_add(1, std::memory_order_relaxed);
+      if (write_pos >= nodes_.size()) {
+        return PushStatus::Closed;
+      }
+      if (nodes_[static_cast<size_t>(write_pos)].one_value.set_value(value)) {
+        //stat_.push_loop_ok(0);
+        return PushStatus::Ok;
+      }
+      //stat_.push_loop_error(0);
+    }
+  }
+
+ private:
+  struct Node {
+    OneValue<T> one_value;
+  };
+  std::atomic<uint64> write_pos_{0};
+  char pad[TD_CONCURRENCY_PAD - sizeof(std::atomic<uint64>)];
+  std::atomic<uint64> read_pos_{0};
+  char pad2[TD_CONCURRENCY_PAD - sizeof(std::atomic<uint64>)];
+  std::vector<Node> nodes_;
+  char pad3[TD_CONCURRENCY_PAD - sizeof(std::vector<Node>)];
+};
+
+template <class T>
+class MpmcQueueOld {
+ public:
+  explicit MpmcQueueOld(size_t threads_n) : MpmcQueueOld(1024, threads_n) {
+  }
+  static std::string get_description() {
+    return "Mpmc queue (fetch and add array queue)";
+  }
+  MpmcQueueOld(size_t block_size, size_t threads_n) : block_size_{block_size}, hazard_pointers_{threads_n} {
+    auto node = std::make_unique<Node>(block_size_);
+    write_pos_ = node.get();
+    read_pos_ = node.get();
+    node.release();
+  }
+
+  MpmcQueueOld(const MpmcQueueOld &other) = delete;
+  MpmcQueueOld &operator=(const MpmcQueueOld &other) = delete;
+  MpmcQueueOld(MpmcQueueOld &&other) = delete;
+  MpmcQueueOld &operator=(MpmcQueueOld &&other) = delete;
+  ~MpmcQueueOld() {
+    auto *ptr = read_pos_.load(std::memory_order_relaxed);
+    while (ptr) {
+      auto *to_delete = ptr;
+      ptr = ptr->next_.load(std::memory_order_relaxed);
+      delete to_delete;
+    }
+    //stat_.dump();
+    //stat_ = MpmcStat();
+  }
+
+  size_t hazard_pointers_to_delele_size_unsafe() const {
+    return hazard_pointers_.to_delete_size_unsafe();
+  }
+  void gc(size_t thread_id) {
+    hazard_pointers_.retire(thread_id);
+  }
+
+  using PushStatus = typename MpmcQueueBlock<T>::PushStatus;
+  using PopStatus = typename MpmcQueueBlock<T>::PopStatus;
+
+  void push(T value, size_t thread_id) {
+    auto hazard_ptr_holder = hazard_pointers_.get_holder(thread_id, 0);
+    while (true) {
+      auto node = hazard_ptr_holder.protect(write_pos_);
+      auto status = node->block.push(value);
+      switch (status) {
+        case PushStatus::Ok:
+          return;
+        case PushStatus::Closed: {
+          auto next = node->next_.load(std::memory_order_acquire);
+          if (next == nullptr) {
+            auto new_node = new Node(block_size_);
+            new_node->block.push(value);
+            if (node->next_.compare_exchange_strong(next, new_node, std::memory_order_acq_rel)) {
+              //stat_.alloc_ok(thread_id);
+              write_pos_.compare_exchange_strong(node, new_node, std::memory_order_acq_rel);
+              return;
+            } else {
+              //stat_.alloc_error(thread_id);
+              new_node->block.pop(value);
+              //CHECK(status == PopStatus::Ok);
+              delete new_node;
+            }
+          }
+          //CHECK(next != nullptr);
+          write_pos_.compare_exchange_strong(node, next, std::memory_order_acq_rel);
+          break;
+        }
+      }
+    }
+  }
+
+  bool try_pop(T &value, size_t thread_id) {
+    auto hazard_ptr_holder = hazard_pointers_.get_holder(thread_id, 0);
+    while (true) {
+      auto node = hazard_ptr_holder.protect(read_pos_);
+      auto status = node->block.try_pop(value);
+      switch (status) {
+        case PopStatus::Ok:
+          return true;
+        case PopStatus::Empty:
+          return false;
+        case PopStatus::Closed: {
+          auto next = node->next_.load(std::memory_order_acquire);
+          if (!next) {
+            return false;
+          }
+          if (read_pos_.compare_exchange_strong(node, next, std::memory_order_acq_rel)) {
+            hazard_ptr_holder.clear();
+            hazard_pointers_.retire(thread_id, node);
+          }
+          break;
+        }
+      }
+    }
+  }
+
+  T pop(size_t thread_id) {
+    T value;
+    while (true) {
+      if (try_pop(value, thread_id)) {
+        return value;
+      }
+      td::this_thread::yield();
+    }
+  }
+
+ private:
+  struct Node {
+    explicit Node(size_t block_size) : block{block_size} {
+    }
+    std::atomic<Node *> next_{nullptr};
+    char pad[TD_CONCURRENCY_PAD - sizeof(std::atomic<Node *>)];
+    MpmcQueueBlock<T> block;
+    //Got pad in MpmcQueueBlock
+  };
+  std::atomic<Node *> write_pos_;
+  char pad[TD_CONCURRENCY_PAD - sizeof(std::atomic<Node *>)];
+  std::atomic<Node *> read_pos_;
+  char pad2[TD_CONCURRENCY_PAD - sizeof(std::atomic<Node *>)];
+  size_t block_size_;
+  HazardPointers<Node, 1> hazard_pointers_;
+  //Got pad in HazardPointers
+};
+
+template <class T>
+class MpmcQueue {
+ public:
+  explicit MpmcQueue(size_t threads_n) : MpmcQueue(1024, threads_n) {
+  }
+  static std::string get_description() {
+    return "NEW Mpmc queue (fetch and add array queue)";
+  }
+  MpmcQueue(size_t block_size, size_t threads_n) : hazard_pointers_{threads_n} {
+    auto node = std::make_unique<Node>();
+    write_pos_ = node.get();
+    read_pos_ = node.get();
+    node.release();
+  }
+
+  MpmcQueue(const MpmcQueue &other) = delete;
+  MpmcQueue &operator=(const MpmcQueue &other) = delete;
+  MpmcQueue(MpmcQueue &&other) = delete;
+  MpmcQueue &operator=(MpmcQueue &&other) = delete;
+  ~MpmcQueue() {
+    auto *ptr = read_pos_.load(std::memory_order_relaxed);
+    while (ptr) {
+      auto *to_delete = ptr;
+      ptr = ptr->next.load(std::memory_order_relaxed);
+      delete to_delete;
+    }
+  }
+
+  size_t hazard_pointers_to_delele_size_unsafe() const {
+    return hazard_pointers_.to_delete_size_unsafe();
+  }
+  void gc(size_t thread_id) {
+    hazard_pointers_.retire(thread_id);
+  }
+
+  void push(T value, size_t thread_id) {
+    SCOPE_EXIT {
+      hazard_pointers_.clear(thread_id, 0);
+    };
+    while (true) {
+      auto node = hazard_pointers_.protect(thread_id, 0, write_pos_);
+      auto &block = node->block;
+      auto pos = block.write_pos++;
+      if (pos >= block.data.size()) {
+        auto next = node->next.load();
+        if (next == nullptr) {
+          auto new_node = new Node{};
+          new_node->block.write_pos++;
+          new_node->block.data[0].set_value(value);
+          Node *null = nullptr;
+          if (node->next.compare_exchange_strong(null, new_node)) {
+            write_pos_.compare_exchange_strong(node, new_node);
+            return;
+          } else {
+            new_node->block.data[0].get_value(value);
+            delete new_node;
+          }
+        } else {
+          write_pos_.compare_exchange_strong(node, next);
+        }
+      } else {
+        if (block.data[static_cast<size_t>(pos)].set_value(value)) {
+          return;
+        }
+      }
+    }
+  }
+
+  bool try_pop(T &value, size_t thread_id) {
+    SCOPE_EXIT {
+      hazard_pointers_.clear(thread_id, 0);
+    };
+    while (true) {
+      auto node = hazard_pointers_.protect(thread_id, 0, read_pos_);
+      auto &block = node->block;
+      if (block.write_pos <= block.read_pos && node->next.load(std::memory_order_relaxed) == nullptr) {
+        return false;
+      }
+      auto pos = block.read_pos++;
+      if (pos >= block.data.size()) {
+        auto next = node->next.load();
+        if (!next) {
+          return false;
+        }
+        if (read_pos_.compare_exchange_strong(node, next)) {
+          hazard_pointers_.clear(thread_id, 0);
+          hazard_pointers_.retire(thread_id, node);
+        }
+      } else {
+        if (block.data[static_cast<size_t>(pos)].get_value(value)) {
+          return true;
+        }
+      }
+    }
+  }
+
+  T pop(size_t thread_id) {
+    T value;
+    while (true) {
+      if (try_pop(value, thread_id)) {
+        return value;
+      }
+      td::this_thread::yield();
+    }
+  }
+
+ private:
+  struct Block {
+    std::atomic<uint64> write_pos{0};
+    char pad[TD_CONCURRENCY_PAD - sizeof(std::atomic<uint64>)];
+    std::atomic<uint64> read_pos{0};
+    char pad2[TD_CONCURRENCY_PAD - sizeof(std::atomic<uint64>)];
+    std::array<OneValue<T>, 1024> data;
+    char pad3[TD_CONCURRENCY_PAD];
+  };
+  struct Node {
+    Node() = default;
+
+    Block block;
+    std::atomic<Node *> next{nullptr};
+    char pad[TD_CONCURRENCY_PAD - sizeof(std::atomic<Node *>)];
+    //Got pad in MpmcQueueBlock
+  };
+  std::atomic<Node *> write_pos_;
+  char pad[TD_CONCURRENCY_PAD - sizeof(std::atomic<Node *>)];
+  std::atomic<Node *> read_pos_;
+  char pad2[TD_CONCURRENCY_PAD - sizeof(std::atomic<Node *>)];
+  HazardPointers<Node, 1> hazard_pointers_;
+  //Got pad in HazardPointers
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/MpmcWaiter.h b/libs/tdlib/td/tdutils/td/utils/MpmcWaiter.h
new file mode 100644
index 0000000000..0f48620e63
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/MpmcWaiter.h
@@ -0,0 +1,106 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/port/thread.h"
+
+#include <atomic>
+#include <condition_variable>
+#include <mutex>
+
+namespace td {
+
+class MpmcWaiter {
+ public:
+  int wait(int yields, uint32 worker_id) {
+    if (yields < RoundsTillSleepy) {
+      td::this_thread::yield();
+      return yields + 1;
+    } else if (yields == RoundsTillSleepy) {
+      auto state = state_.load(std::memory_order_relaxed);
+      if (!State::has_worker(state)) {
+        auto new_state = State::with_worker(state, worker_id);
+        if (state_.compare_exchange_strong(state, new_state)) {
+          td::this_thread::yield();
+          return yields + 1;
+        }
+        if (state == State::awake()) {
+          return 0;
+        }
+      }
+      td::this_thread::yield();
+      return 0;
+    } else if (yields < RoundsTillAsleep) {
+      auto state = state_.load(std::memory_order_acquire);
+      if (State::still_sleepy(state, worker_id)) {
+        td::this_thread::yield();
+        return yields + 1;
+      }
+      return 0;
+    } else {
+      auto state = state_.load(std::memory_order_acquire);
+      if (State::still_sleepy(state, worker_id)) {
+        std::unique_lock<std::mutex> lock(mutex_);
+        if (state_.compare_exchange_strong(state, State::asleep(), std::memory_order_acq_rel)) {
+          condition_variable_.wait(lock);
+        }
+      }
+      return 0;
+    }
+  }
+
+  int stop_wait(int yields, uint32 worker_id) {
+    if (yields > RoundsTillSleepy) {
+      notify_cold();
+    }
+    return 0;
+  }
+
+  void notify() {
+    if (state_.load(std::memory_order_acquire) == State::awake()) {
+      return;
+    }
+    notify_cold();
+  }
+
+ private:
+  struct State {
+    static constexpr uint32 awake() {
+      return 0;
+    }
+    static constexpr uint32 asleep() {
+      return 1;
+    }
+    static bool is_asleep(uint32 state) {
+      return (state & 1) != 0;
+    }
+    static bool has_worker(uint32 state) {
+      return (state >> 1) != 0;
+    }
+    static int32 with_worker(uint32 state, uint32 worker) {
+      return state | ((worker + 1) << 1);
+    }
+    static bool still_sleepy(uint32 state, uint32 worker) {
+      return (state >> 1) == (worker + 1);
+    }
+  };
+  enum { RoundsTillSleepy = 32, RoundsTillAsleep = 64 };
+  std::atomic<uint32> state_{State::awake()};
+  std::mutex mutex_;
+  std::condition_variable condition_variable_;
+
+  void notify_cold() {
+    auto old_state = state_.exchange(State::awake(), std::memory_order_release);
+    if (State::is_asleep(old_state)) {
+      std::lock_guard<std::mutex> guard(mutex_);
+      condition_variable_.notify_all();
+    }
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/MpscLinkQueue.h b/libs/tdlib/td/tdutils/td/utils/MpscLinkQueue.h
new file mode 100644
index 0000000000..4398c7503d
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/MpscLinkQueue.h
@@ -0,0 +1,174 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+
+#include <atomic>
+
+namespace td {
+//NB: holder of the queue holds all responsibility of freeing its nodes
+class MpscLinkQueueImpl {
+ public:
+  class Node;
+  class Reader;
+
+  void push(Node *node) {
+    node->next_ = head_.load(std::memory_order_relaxed);
+    while (!head_.compare_exchange_strong(node->next_, node, std::memory_order_release, std::memory_order_relaxed)) {
+    }
+  }
+
+  void push_unsafe(Node *node) {
+    node->next_ = head_.load(std::memory_order_relaxed);
+    head_.store(node, std::memory_order_relaxed);
+  }
+
+  void pop_all(Reader &reader) {
+    return reader.add(head_.exchange(nullptr, std::memory_order_acquire));
+  }
+
+  void pop_all_unsafe(Reader &reader) {
+    return reader.add(head_.exchange(nullptr, std::memory_order_relaxed));
+  }
+
+  class Node {
+    friend class MpscLinkQueueImpl;
+    Node *next_{nullptr};
+  };
+
+  class Reader {
+   public:
+    Node *read() {
+      auto old_head = head_;
+      if (head_) {
+        head_ = head_->next_;
+      }
+      return old_head;
+    }
+    void delay(Node *node) {
+      node->next_ = head_;
+      if (!head_) {
+        tail_ = node;
+      }
+      head_ = node;
+    }
+    size_t calc_size() const {
+      size_t res = 0;
+      for (auto it = head_; it != nullptr; it = it->next_, res++) {
+      }
+      return res;
+    }
+
+   private:
+    friend class MpscLinkQueueImpl;
+    void add(Node *node) {
+      if (node == nullptr) {
+        return;
+      }
+      // Reverse list
+      Node *tail = node;
+      Node *head = nullptr;
+      while (node) {
+        auto next = node->next_;
+        node->next_ = head;
+        head = node;
+        node = next;
+      }
+      if (head_ == nullptr) {
+        head_ = head;
+      } else {
+        tail_->next_ = head;
+      }
+      tail_ = tail;
+    }
+    Node *head_{nullptr};
+    Node *tail_{nullptr};
+  };
+
+ private:
+  std::atomic<Node *> head_{nullptr};
+};
+
+// Uses MpscLinkQueueImpl.
+// Node should have to_mpsc_link_queue_node and from_mpsc_link_queue_node functions
+template <class Node>
+class MpscLinkQueue {
+ public:
+  void push(Node node) {
+    impl_.push(node.to_mpsc_link_queue_node());
+  }
+  void push_unsafe(Node node) {
+    impl_.push_unsafe(node.to_mpsc_link_queue_node());
+  }
+  class Reader {
+   public:
+    ~Reader() {
+      CHECK(!read());
+    }
+    Node read() {
+      auto node = impl_.read();
+      if (!node) {
+        return {};
+      }
+      return Node::from_mpsc_link_queue_node(node);
+    }
+    void delay(Node node) {
+      impl_.delay(node.to_mpsc_link_queue_node());
+    }
+    size_t calc_size() const {
+      return impl_.calc_size();
+    }
+
+   private:
+    friend class MpscLinkQueue;
+
+    MpscLinkQueueImpl::Reader impl_;
+    MpscLinkQueueImpl::Reader &impl() {
+      return impl_;
+    }
+  };
+
+  void pop_all(Reader &reader) {
+    return impl_.pop_all(reader.impl());
+  }
+  void pop_all_unsafe(Reader &reader) {
+    return impl_.pop_all_unsafe(reader.impl());
+  }
+
+ private:
+  MpscLinkQueueImpl impl_;
+};
+
+template <class Value>
+class MpscLinkQueueUniquePtrNode {
+ public:
+  MpscLinkQueueUniquePtrNode() = default;
+  explicit MpscLinkQueueUniquePtrNode(std::unique_ptr<Value> ptr) : ptr_(std::move(ptr)) {
+  }
+
+  MpscLinkQueueImpl::Node *to_mpsc_link_queue_node() {
+    return ptr_.release()->to_mpsc_link_queue_node();
+  }
+  static MpscLinkQueueUniquePtrNode<Value> from_mpsc_link_queue_node(td::MpscLinkQueueImpl::Node *node) {
+    return MpscLinkQueueUniquePtrNode<Value>(std::unique_ptr<Value>(Value::from_mpsc_link_queue_node(node)));
+  }
+
+  explicit operator bool() {
+    return ptr_ != nullptr;
+  }
+
+  Value &value() {
+    return *ptr_;
+  }
+
+ private:
+  std::unique_ptr<Value> ptr_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/MpscPollableQueue.h b/libs/tdlib/td/tdutils/td/utils/MpscPollableQueue.h
new file mode 100644
index 0000000000..89d2df8693
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/MpscPollableQueue.h
@@ -0,0 +1,154 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/misc.h"
+#include "td/utils/port/EventFd.h"
+#include "td/utils/SpinLock.h"
+
+#if !TD_EVENTFD_UNSUPPORTED
+#if !TD_WINDOWS
+#include <poll.h>
+#include <sched.h>
+#endif
+
+#include <utility>
+
+namespace td {
+// interface like in PollableQueue
+template <class ValueT>
+class MpscPollableQueue {
+ public:
+  int reader_wait_nonblock() {
+    auto ready = reader_vector_.size() - reader_pos_;
+    if (ready != 0) {
+      return narrow_cast<int>(ready);
+    }
+
+    auto guard = lock_.lock();
+    if (writer_vector_.empty()) {
+      event_fd_.acquire();
+      wait_event_fd_ = true;
+      return 0;
+    } else {
+      reader_vector_.clear();
+      reader_pos_ = 0;
+      std::swap(writer_vector_, reader_vector_);
+      return narrow_cast<int>(reader_vector_.size());
+    }
+  }
+  ValueT reader_get_unsafe() {
+    return std::move(reader_vector_[reader_pos_++]);
+  }
+  void reader_flush() {
+    //nop
+  }
+  void writer_put(ValueT value) {
+    auto guard = lock_.lock();
+    writer_vector_.push_back(std::move(value));
+    if (wait_event_fd_) {
+      wait_event_fd_ = false;
+      event_fd_.release();
+    }
+  }
+  EventFd &reader_get_event_fd() {
+    return event_fd_;
+  }
+  void writer_flush() {
+    //nop
+  }
+
+  void init() {
+    event_fd_.init();
+  }
+  void destroy() {
+    if (!event_fd_.empty()) {
+      event_fd_.close();
+      wait_event_fd_ = false;
+      writer_vector_.clear();
+      reader_vector_.clear();
+      reader_pos_ = 0;
+    }
+  }
+
+// Just example of usage
+#if !TD_WINDOWS
+  int reader_wait() {
+    int res;
+
+    while ((res = reader_wait_nonblock()) == 0) {
+      // TODO: reader_flush?
+      pollfd fd;
+      fd.fd = reader_get_event_fd().get_fd().get_native_fd();
+      fd.events = POLLIN;
+      poll(&fd, 1, -1);
+    }
+    return res;
+  }
+#endif
+
+ private:
+  SpinLock lock_;
+  bool wait_event_fd_{false};
+  EventFd event_fd_;
+  std::vector<ValueT> writer_vector_;
+  std::vector<ValueT> reader_vector_;
+  size_t reader_pos_{0};
+};
+
+}  // namespace td
+
+#else
+#include "td/utils/logging.h"
+
+namespace td {
+
+// dummy implementation which shouldn't be used
+
+template <class T>
+class MpscPollableQueue {
+ public:
+  using ValueType = T;
+
+  void init() {
+    UNREACHABLE();
+  }
+
+  template <class PutValueType>
+  void writer_put(PutValueType &&value) {
+    UNREACHABLE();
+  }
+
+  void writer_flush() {
+    UNREACHABLE();
+  }
+
+  int reader_wait_nonblock() {
+    UNREACHABLE();
+    return 0;
+  }
+
+  ValueType reader_get_unsafe() {
+    UNREACHABLE();
+    return ValueType();
+  }
+
+  void reader_flush() {
+    UNREACHABLE();
+  }
+
+  MpscPollableQueue() = default;
+  MpscPollableQueue(const MpscPollableQueue &) = delete;
+  MpscPollableQueue &operator=(const MpscPollableQueue &) = delete;
+  MpscPollableQueue(MpscPollableQueue &&) = delete;
+  MpscPollableQueue &operator=(MpscPollableQueue &&) = delete;
+  ~MpscPollableQueue() = default;
+};
+
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/Named.h b/libs/tdlib/td/tdutils/td/utils/Named.h
new file mode 100644
index 0000000000..202de5f7d4
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Named.h
@@ -0,0 +1,27 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+
+namespace td {
+
+class Named {
+ public:
+  Slice get_name() const {
+    return name_;
+  }
+  void set_name(Slice name) {
+    name_ = name.str();
+  }
+
+ private:
+  string name_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/ObjectPool.h b/libs/tdlib/td/tdutils/td/utils/ObjectPool.h
new file mode 100644
index 0000000000..e6e4549dbb
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/ObjectPool.h
@@ -0,0 +1,249 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+
+#include <atomic>
+#include <memory>
+#include <utility>
+
+namespace td {
+// It is draft object pool implementaion
+//
+// Compared with std::shared_ptr:
+// + WeakPtr are much faster. Just pointer copy. No barriers, no atomics.
+// - We can't destroy object, because we don't know if it is pointed to by some weak pointer
+//
+template <class DataT>
+class ObjectPool {
+  struct Storage;
+
+ public:
+  class WeakPtr {
+   public:
+    WeakPtr() : generation_(-1), storage_(nullptr) {
+    }
+    WeakPtr(int32 generation, Storage *storage) : generation_(generation), storage_(storage) {
+    }
+
+    DataT &operator*() const {
+      return storage_->data;
+    }
+
+    DataT *operator->() const {
+      return &**this;
+    }
+
+    // Pattern of usage: 1. Read an object 2. Check if read was valid via is_alive
+    //
+    // It is not very usual case of acquire/release use.
+    // Instead of publishing an object via some flag we do the opposite.
+    // We publish new generation via destruction of the data.
+    // In usual case if we see a flag then we are able to use an object.
+    // In our case if we have used an object and it is already invalid, then generation will mismatch
+    bool is_alive() const {
+      if (!storage_) {
+        return false;
+      }
+      std::atomic_thread_fence(std::memory_order_acquire);
+      return generation_ == storage_->generation.load(std::memory_order_relaxed);
+    }
+
+    // Used for ActorId
+    bool is_alive_unsafe() const {
+      if (!storage_) {
+        return false;
+      }
+      return generation_ == storage_->generation.load(std::memory_order_relaxed);
+    }
+
+    bool empty() const {
+      return storage_ == nullptr;
+    }
+    void clear() {
+      generation_ = -1;
+      storage_ = nullptr;
+    }
+    int32 generation() {
+      return generation_;
+    }
+
+   private:
+    int32 generation_;
+    Storage *storage_;
+  };
+
+  class OwnerPtr {
+   public:
+    OwnerPtr() = default;
+    OwnerPtr(const OwnerPtr &) = delete;
+    OwnerPtr &operator=(const OwnerPtr &) = delete;
+    OwnerPtr(OwnerPtr &&other) : storage_(other.storage_), parent_(other.parent_) {
+      other.storage_ = nullptr;
+      other.parent_ = nullptr;
+    }
+    OwnerPtr &operator=(OwnerPtr &&other) {
+      if (this != &other) {
+        storage_ = other.storage_;
+        parent_ = other.parent_;
+        other.storage_ = nullptr;
+        other.parent_ = nullptr;
+      }
+      return *this;
+    }
+    ~OwnerPtr() {
+      reset();
+    }
+
+    DataT *get() {
+      return &storage_->data;
+    }
+    DataT &operator*() {
+      return *get();
+    }
+    DataT *operator->() {
+      return get();
+    }
+
+    const DataT *get() const {
+      return &storage_->data;
+    }
+    const DataT &operator*() const {
+      return *get();
+    }
+    const DataT *operator->() const {
+      return get();
+    }
+
+    WeakPtr get_weak() {
+      return WeakPtr(storage_->generation.load(std::memory_order_relaxed), storage_);
+    }
+    int32 generation() {
+      return storage_->generation.load(std::memory_order_relaxed);
+    }
+
+    Storage *release() {
+      auto result = storage_;
+      storage_ = nullptr;
+      return result;
+    }
+
+    bool empty() const {
+      return storage_ == nullptr;
+    }
+
+    void reset() {
+      if (storage_ != nullptr) {
+        // for crazy cases when data owns owner pointer to itself.
+        auto tmp = storage_;
+        storage_ = nullptr;
+        parent_->release(OwnerPtr(tmp, parent_));
+      }
+    }
+
+   private:
+    friend class ObjectPool;
+    OwnerPtr(Storage *storage, ObjectPool<DataT> *parent) : storage_(storage), parent_(parent) {
+    }
+    Storage *storage_ = nullptr;
+    ObjectPool<DataT> *parent_ = nullptr;
+  };
+
+  template <class... ArgsT>
+  OwnerPtr create(ArgsT &&... args) {
+    Storage *storage = get_storage();
+    storage->init_data(std::forward<ArgsT>(args)...);
+    return OwnerPtr(storage, this);
+  }
+
+  OwnerPtr create_empty() {
+    Storage *storage = get_storage();
+    return OwnerPtr(storage, this);
+  }
+
+  void set_check_empty(bool flag) {
+    check_empty_flag_ = flag;
+  }
+
+  void release(OwnerPtr &&owner_ptr) {
+    Storage *storage = owner_ptr.release();
+    storage->destroy_data();
+    release_storage(storage);
+  }
+
+  ObjectPool() = default;
+  ObjectPool(const ObjectPool &) = delete;
+  ObjectPool &operator=(const ObjectPool &) = delete;
+  ObjectPool(ObjectPool &&other) = delete;
+  ObjectPool &operator=(ObjectPool &&other) = delete;
+  ~ObjectPool() {
+    while (head_.load()) {
+      auto to_delete = head_.load();
+      head_ = to_delete->next;
+      delete to_delete;
+      storage_count_--;
+    }
+    CHECK(storage_count_.load() == 0) << storage_count_.load();
+  }
+
+ private:
+  struct Storage {
+    // union {
+    DataT data;
+    //};
+    Storage *next = nullptr;
+    std::atomic<int32> generation{1};
+
+    template <class... ArgsT>
+    void init_data(ArgsT &&... args) {
+      // new  (&data) DataT(std::forward<ArgsT>(args)...);
+      data = DataT(std::forward<ArgsT>(args)...);
+    }
+    void destroy_data() {
+      generation.fetch_add(1, std::memory_order_relaxed);
+      std::atomic_thread_fence(std::memory_order_release);
+      data.clear();
+    }
+  };
+
+  std::atomic<int32> storage_count_{0};
+  std::atomic<Storage *> head_{static_cast<Storage *>(nullptr)};
+  bool check_empty_flag_ = false;
+
+  // TODO(perf): allocation Storages in chunks? Anyway we won't be able to release them.
+  // TODO(perf): memory order
+  // TODO(perf): use another non lockfree list for release on the same thread
+  // only one thread, so no aba problem
+  Storage *get_storage() {
+    if (head_.load() == nullptr) {
+      storage_count_++;
+      return new Storage();
+    }
+    Storage *res;
+    while (true) {
+      res = head_.load();
+      auto *next = res->next;
+      if (head_.compare_exchange_weak(res, next)) {
+        break;
+      }
+    }
+    return res;
+  }
+  // release can be called from other thread
+  void release_storage(Storage *storage) {
+    while (true) {
+      auto *save_head = head_.load();
+      storage->next = save_head;
+      if (head_.compare_exchange_weak(save_head, storage)) {
+        break;
+      }
+    }
+  }
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Observer.h b/libs/tdlib/td/tdutils/td/utils/Observer.h
new file mode 100644
index 0000000000..8511e0ce8b
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Observer.h
@@ -0,0 +1,41 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+namespace td {
+
+class ObserverBase {
+ public:
+  ObserverBase() = default;
+  ObserverBase(const ObserverBase &) = delete;
+  ObserverBase &operator=(const ObserverBase &) = delete;
+  ObserverBase(ObserverBase &&) = delete;
+  ObserverBase &operator=(ObserverBase &&) = delete;
+  virtual ~ObserverBase() = default;
+
+  virtual void notify() = 0;
+};
+
+class Observer : ObserverBase {
+ public:
+  Observer() = default;
+  explicit Observer(unique_ptr<ObserverBase> &&ptr) : observer_ptr_(std::move(ptr)) {
+  }
+
+  void notify() override {
+    if (observer_ptr_) {
+      observer_ptr_->notify();
+    }
+  }
+
+ private:
+  unique_ptr<ObserverBase> observer_ptr_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/OptionsParser.h b/libs/tdlib/td/tdutils/td/utils/OptionsParser.h
new file mode 100644
index 0000000000..6ac0385575
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/OptionsParser.h
@@ -0,0 +1,150 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+
+#include <functional>
+#include <string>
+
+#if !TD_WINDOWS
+#include <getopt.h>
+#endif
+
+namespace td {
+
+class OptionsParser {
+ public:
+  class Option {
+   public:
+    enum Type { NoArg, Arg, OptionalArg };
+    Type type;
+    char short_key;
+    std::string long_key;
+    std::string description;
+    std::function<Status(Slice)> arg_callback;
+  };
+
+  void set_description(std::string description) {
+    description_ = std::move(description);
+  }
+
+  void add_option(Option::Type type, char short_key, Slice long_key, Slice description,
+                  std::function<Status(Slice)> callback) {
+    options_.push_back(Option{type, short_key, long_key.str(), description.str(), std::move(callback)});
+  }
+
+  void add_option(char short_key, Slice long_key, Slice description, std::function<Status(Slice)> callback) {
+    add_option(Option::Type::Arg, short_key, long_key, description, std::move(callback));
+  }
+
+  void add_option(char short_key, Slice long_key, Slice description, std::function<Status(void)> callback) {
+    // Ouch. There must be some better way
+    add_option(Option::Type::NoArg, short_key, long_key, description,
+               std::bind([](std::function<Status(void)> &func, Slice) { return func(); }, std::move(callback),
+                         std::placeholders::_1));
+  }
+
+  Result<int> run(int argc, char *argv[]) TD_WARN_UNUSED_RESULT {
+#if TD_WINDOWS
+    return -1;
+#else
+    // use getopt. long keys are not supported for now
+    char buff[1024];
+    StringBuilder sb({buff, sizeof(buff)});
+    for (auto &opt : options_) {
+      CHECK(opt.type != Option::OptionalArg);
+      sb << opt.short_key;
+      if (opt.type == Option::Arg) {
+        sb << ":";
+      }
+    }
+    if (sb.is_error()) {
+      return Status::Error("Can't parse options");
+    }
+    CSlice short_options = sb.as_cslice();
+
+    vector<option> long_options;
+    for (auto &opt : options_) {
+      if (opt.long_key.empty()) {
+        continue;
+      }
+      option o;
+      o.flag = nullptr;
+      o.val = opt.short_key;
+      o.has_arg = opt.type == Option::Arg ? required_argument : no_argument;
+      o.name = opt.long_key.c_str();
+      long_options.push_back(o);
+    }
+    long_options.push_back({nullptr, 0, nullptr, 0});
+
+    while (true) {
+      int opt_i = getopt_long(argc, argv, short_options.c_str(), &long_options[0], nullptr);
+      if (opt_i == ':') {
+        return Status::Error("Missing argument");
+      }
+      if (opt_i == '?') {
+        return Status::Error("Unrecognized option");
+      }
+      if (opt_i == -1) {
+        break;
+      }
+      bool found = false;
+      for (auto &opt : options_) {
+        if (opt.short_key == opt_i) {
+          Slice arg;
+          if (opt.type == Option::Arg) {
+            arg = Slice(optarg);
+          }
+          auto status = opt.arg_callback(arg);
+          if (status.is_error()) {
+            return std::move(status);
+          }
+          found = true;
+          break;
+        }
+      }
+      if (!found) {
+        return Status::Error("Unknown argument");
+      }
+    }
+    return optind;
+#endif
+  }
+
+  friend StringBuilder &operator<<(StringBuilder &sb, const OptionsParser &o) {
+    sb << o.description_ << "\n";
+    for (auto &opt : o.options_) {
+      sb << "-" << opt.short_key;
+      if (!opt.long_key.empty()) {
+        sb << "|--" << opt.long_key;
+      }
+      if (opt.type == Option::OptionalArg) {
+        sb << "[";
+      }
+      if (opt.type != Option::NoArg) {
+        sb << "<arg>";
+      }
+      if (opt.type == Option::OptionalArg) {
+        sb << "]";
+      }
+      sb << "\t" << opt.description;
+      sb << "\n";
+    }
+    return sb;
+  }
+
+ private:
+  std::vector<Option> options_;
+  std::string description_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/OrderedEventsProcessor.h b/libs/tdlib/td/tdutils/td/utils/OrderedEventsProcessor.h
new file mode 100644
index 0000000000..4515b74684
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/OrderedEventsProcessor.h
@@ -0,0 +1,87 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+
+#include <utility>
+
+namespace td {
+
+// Process states in order defined by their Id
+template <class DataT>
+class OrderedEventsProcessor {
+ public:
+  using SeqNo = uint64;
+
+  OrderedEventsProcessor() = default;
+  explicit OrderedEventsProcessor(SeqNo offset) : offset_(offset), begin_(offset_), end_(offset_) {
+  }
+
+  template <class FromDataT, class FunctionT>
+  void add(SeqNo seq_no, FromDataT &&data, FunctionT &&function) {
+    CHECK(seq_no >= begin_) << seq_no << ">=" << begin_;  // or ignore?
+
+    if (seq_no == begin_) {  // run now
+      begin_++;
+      function(seq_no, std::forward<FromDataT>(data));
+
+      while (begin_ < end_) {
+        auto &data_flag = data_array_[static_cast<size_t>(begin_ - offset_)];
+        if (!data_flag.second) {
+          break;
+        }
+        function(begin_, std::move(data_flag.first));
+        data_flag.second = false;
+        begin_++;
+      }
+      if (begin_ > end_) {
+        end_ = begin_;
+      }
+      if (begin_ == end_) {
+        offset_ = begin_;
+      }
+
+      // try_compactify
+      auto begin_pos = static_cast<size_t>(begin_ - offset_);
+      if (begin_pos > 5 && begin_pos * 2 > data_array_.size()) {
+        data_array_.erase(data_array_.begin(), data_array_.begin() + begin_pos);
+        offset_ = begin_;
+      }
+    } else {
+      auto pos = static_cast<size_t>(seq_no - offset_);
+      auto need_size = pos + 1;
+      if (data_array_.size() < need_size) {
+        data_array_.resize(need_size);
+      }
+      data_array_[pos].first = std::forward<FromDataT>(data);
+      data_array_[pos].second = true;
+      if (end_ < seq_no + 1) {
+        end_ = seq_no + 1;
+      }
+    }
+  }
+
+  bool has_events() const {
+    return begin_ != end_;
+  }
+  SeqNo max_unfinished_seq_no() {
+    return end_ - 1;
+  }
+  SeqNo max_finished_seq_no() {
+    return begin_ - 1;
+  }
+
+ private:
+  SeqNo offset_ = 1;
+  SeqNo begin_ = 1;
+  SeqNo end_ = 1;
+  std::vector<std::pair<DataT, bool>> data_array_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Parser.h b/libs/tdlib/td/tdutils/td/utils/Parser.h
new file mode 100644
index 0000000000..06e95bf807
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Parser.h
@@ -0,0 +1,183 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <cstring>
+#include <utility>
+
+namespace td {
+
+class Parser {
+ public:
+  explicit Parser(MutableSlice data) : ptr_(data.begin()), end_(data.end()), status_() {
+  }
+  Parser(Parser &&other) : ptr_(other.ptr_), end_(other.end_), status_(std::move(other.status_)) {
+    other.clear();
+  }
+  Parser &operator=(Parser &&other) {
+    if (&other == this) {
+      return *this;
+    }
+    ptr_ = other.ptr_;
+    end_ = other.end_;
+    status_ = std::move(other.status_);
+    other.clear();
+    return *this;
+  }
+  Parser(const Parser &) = delete;
+  Parser &operator=(const Parser &) = delete;
+  ~Parser() = default;
+
+  bool empty() const {
+    return ptr_ == end_;
+  }
+  void clear() {
+    ptr_ = nullptr;
+    end_ = ptr_;
+    status_ = Status::OK();
+  }
+
+  MutableSlice read_till_nofail(char c) {
+    if (status_.is_error()) {
+      return MutableSlice();
+    }
+    char *till = reinterpret_cast<char *>(std::memchr(ptr_, c, end_ - ptr_));
+    if (till == nullptr) {
+      till = end_;
+    }
+    MutableSlice result(ptr_, till);
+    ptr_ = till;
+    return result;
+  }
+
+  MutableSlice read_till_nofail(Slice str) {
+    if (status_.is_error()) {
+      return MutableSlice();
+    }
+    char *best_till = end_;
+    for (auto c : str) {
+      char *till = reinterpret_cast<char *>(std::memchr(ptr_, c, end_ - ptr_));
+      if (till != nullptr && till < best_till) {
+        best_till = till;
+      }
+    }
+    MutableSlice result(ptr_, best_till);
+    ptr_ = best_till;
+    return result;
+  }
+
+  template <class F>
+  MutableSlice read_while(const F &f) {
+    auto save_ptr = ptr_;
+    while (ptr_ != end_ && f(*ptr_)) {
+      ptr_++;
+    }
+    return MutableSlice(save_ptr, ptr_);
+  }
+  MutableSlice read_all() {
+    auto save_ptr = ptr_;
+    ptr_ = end_;
+    return MutableSlice(save_ptr, ptr_);
+  }
+
+  MutableSlice read_till(char c) {
+    if (status_.is_error()) {
+      return MutableSlice();
+    }
+    MutableSlice res = read_till_nofail(c);
+    if (ptr_ == end_ || ptr_[0] != c) {
+      status_ = Status::Error(PSLICE() << "Read till " << tag("char", c) << " failed");
+      return MutableSlice();
+    }
+    return res;
+  }
+
+  char peek_char() {
+    if (ptr_ == end_) {
+      return 0;
+    }
+    return *ptr_;
+  }
+
+  char *ptr() {
+    return ptr_;
+  }
+
+  void skip_nofail(char c) {
+    if (ptr_ != end_ && ptr_[0] == c) {
+      ptr_++;
+    }
+  }
+  void skip(char c) {
+    if (status_.is_error()) {
+      return;
+    }
+    if (ptr_ == end_ || ptr_[0] != c) {
+      status_ = Status::Error(PSLICE() << "Skip " << tag("char", c) << " failed");
+      return;
+    }
+    ptr_++;
+  }
+  bool try_skip(char c) {
+    if (ptr_ != end_ && ptr_[0] == c) {
+      ptr_++;
+      return true;
+    }
+    return false;
+  }
+
+  void skip_till_not(Slice str) {
+    while (ptr_ != end_) {
+      if (std::memchr(str.data(), *ptr_, str.size()) == nullptr) {
+        break;
+      }
+      ptr_++;
+    }
+  }
+  void skip_whitespaces() {
+    skip_till_not(" \t\r\n");
+  }
+
+  MutableSlice data() const {
+    return MutableSlice(ptr_, end_);
+  }
+
+  Status &status() {
+    return status_;
+  }
+
+  bool start_with(Slice prefix) {
+    if (prefix.size() + ptr_ > end_) {
+      return false;
+    }
+    return std::memcmp(prefix.begin(), ptr_, prefix.size()) == 0;
+  }
+
+  bool skip_start_with(Slice prefix) {
+    if (start_with(prefix)) {
+      advance(prefix.size());
+      return true;
+    }
+    return false;
+  }
+
+  void advance(size_t diff) {
+    ptr_ += diff;
+    CHECK(ptr_ <= end_);
+  }
+
+ private:
+  char *ptr_;
+  char *end_;
+  Status status_;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/PathView.h b/libs/tdlib/td/tdutils/td/utils/PathView.h
new file mode 100644
index 0000000000..edb5d7c127
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/PathView.h
@@ -0,0 +1,116 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/misc.h"
+#include "td/utils/Slice.h"
+
+namespace td {
+
+class PathView {
+ public:
+  explicit PathView(Slice path) : path_(path) {
+    last_slash_ = narrow_cast<int32>(path_.size()) - 1;
+    while (last_slash_ >= 0 && !is_slash(path_[last_slash_])) {
+      last_slash_--;
+    }
+
+    last_dot_ = static_cast<int32>(path_.size());
+    for (auto i = last_dot_ - 1; i > last_slash_ + 1; i--) {
+      if (path_[i] == '.') {
+        last_dot_ = i;
+        break;
+      }
+    }
+  }
+
+  bool empty() const {
+    return path_.empty();
+  }
+
+  bool is_dir() const {
+    if (empty()) {
+      return false;
+    }
+    return is_slash(path_.back());
+  }
+
+  Slice parent_dir() const {
+    return Slice(path_.begin(), last_slash_ + 1);
+  }
+
+  Slice extension() const {
+    if (last_dot_ == static_cast<int32>(path_.size())) {
+      return Slice();
+    }
+    return path_.substr(last_dot_ + 1);
+  }
+
+  Slice without_extension() const {
+    return Slice(path_.begin(), last_dot_);
+  }
+
+  Slice file_stem() const {
+    return path_.substr(last_slash_ + 1, last_dot_ - last_slash_ - 1);
+  }
+
+  Slice file_name() const {
+    return path_.substr(last_slash_ + 1);
+  }
+
+  Slice path() const {
+    return path_;
+  }
+
+  bool is_absolute() const {
+    return !empty() && (is_slash(path_[0]) || (path_.size() >= 3 && path_[1] == ':' && is_slash(path_[2])));
+  }
+
+  bool is_relative() const {
+    return !is_absolute();
+  }
+
+  static Slice relative(Slice path, Slice dir, bool force = false) {
+    if (begins_with(path, dir)) {
+      path.remove_prefix(dir.size());
+      return path;
+    }
+    if (force) {
+      return Slice();
+    }
+    return path;
+  }
+
+  static Slice dir_and_file(Slice path) {
+    auto last_slash = static_cast<int32>(path.size()) - 1;
+    while (last_slash >= 0 && !is_slash(path[last_slash])) {
+      last_slash--;
+    }
+    if (last_slash < 0) {
+      return Slice();
+    }
+    last_slash--;
+    while (last_slash >= 0 && !is_slash(path[last_slash])) {
+      last_slash--;
+    }
+    if (last_slash < 0) {
+      return Slice();
+    }
+    return path.substr(last_slash + 1);
+  }
+
+ private:
+  static bool is_slash(char c) {
+    return c == '/' || c == '\\';
+  }
+
+  Slice path_;
+  int32 last_slash_;
+  int32 last_dot_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Random.cpp b/libs/tdlib/td/tdutils/td/utils/Random.cpp
new file mode 100644
index 0000000000..db11df4dfa
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Random.cpp
@@ -0,0 +1,108 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/Random.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/port/thread_local.h"
+
+#if TD_HAVE_OPENSSL
+#include <openssl/rand.h>
+#endif
+
+#include <cstring>
+#include <limits>
+#include <random>
+
+namespace td {
+
+#if TD_HAVE_OPENSSL
+void Random::secure_bytes(MutableSlice dest) {
+  Random::secure_bytes(dest.ubegin(), dest.size());
+}
+
+void Random::secure_bytes(unsigned char *ptr, size_t size) {
+  constexpr size_t buf_size = 512;
+  static TD_THREAD_LOCAL unsigned char *buf;  // static zero-initialized
+  static TD_THREAD_LOCAL size_t buf_pos;
+  if (init_thread_local<unsigned char[]>(buf, buf_size)) {
+    buf_pos = buf_size;
+  }
+
+  auto ready = min(size, buf_size - buf_pos);
+  if (ready != 0) {
+    std::memcpy(ptr, buf + buf_pos, ready);
+    buf_pos += ready;
+    ptr += ready;
+    size -= ready;
+    if (size == 0) {
+      return;
+    }
+  }
+  if (size < buf_size) {
+    int err = RAND_bytes(buf, static_cast<int>(buf_size));
+    // TODO: it CAN fail
+    LOG_IF(FATAL, err != 1);
+    buf_pos = size;
+    std::memcpy(ptr, buf, size);
+    return;
+  }
+
+  CHECK(size <= static_cast<size_t>(std::numeric_limits<int>::max()));
+  int err = RAND_bytes(ptr, static_cast<int>(size));
+  // TODO: it CAN fail
+  LOG_IF(FATAL, err != 1);
+}
+
+int32 Random::secure_int32() {
+  int32 res = 0;
+  secure_bytes(reinterpret_cast<unsigned char *>(&res), sizeof(int32));
+  return res;
+}
+
+int64 Random::secure_int64() {
+  int64 res = 0;
+  secure_bytes(reinterpret_cast<unsigned char *>(&res), sizeof(int64));
+  return res;
+}
+#endif
+
+static unsigned int rand_device_helper() {
+  static TD_THREAD_LOCAL std::random_device *rd;
+  init_thread_local<std::random_device>(rd);
+  return (*rd)();
+}
+
+uint32 Random::fast_uint32() {
+  static TD_THREAD_LOCAL std::mt19937 *gen;
+  if (!gen) {
+    auto &rg = rand_device_helper;
+    std::seed_seq seq{rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg()};
+    init_thread_local<std::mt19937>(gen, seq);
+  }
+  return static_cast<uint32>((*gen)());
+}
+
+uint64 Random::fast_uint64() {
+  static TD_THREAD_LOCAL std::mt19937_64 *gen;
+  if (!gen) {
+    auto &rg = rand_device_helper;
+    std::seed_seq seq{rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg()};
+    init_thread_local<std::mt19937_64>(gen, seq);
+  }
+  return static_cast<uint64>((*gen)());
+}
+
+int Random::fast(int min, int max) {
+  if (min == std::numeric_limits<int>::min() && max == std::numeric_limits<int>::max()) {
+    // to prevent integer overflow and division by zero
+    min++;
+  }
+  CHECK(min <= max);
+  return static_cast<int>(min + fast_uint32() % (max - min + 1));  // TODO signed_cast
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Random.h b/libs/tdlib/td/tdutils/td/utils/Random.h
new file mode 100644
index 0000000000..efe5d64618
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Random.h
@@ -0,0 +1,30 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+
+namespace td {
+
+class Random {
+ public:
+#if TD_HAVE_OPENSSL
+  static void secure_bytes(MutableSlice dest);
+  static void secure_bytes(unsigned char *ptr, size_t size);
+  static int32 secure_int32();
+  static int64 secure_int64();
+#endif
+
+  static uint32 fast_uint32();
+  static uint64 fast_uint64();
+
+  // distribution is not uniform, min and max are included
+  static int fast(int min, int max);
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/ScopeGuard.h b/libs/tdlib/td/tdutils/td/utils/ScopeGuard.h
new file mode 100644
index 0000000000..a914ce357c
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/ScopeGuard.h
@@ -0,0 +1,76 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+#include <cstdlib>
+#include <memory>
+#include <type_traits>
+#include <utility>
+
+namespace td {
+class Guard {
+ public:
+  Guard() = default;
+  Guard(const Guard &other) = delete;
+  Guard &operator=(const Guard &other) = delete;
+  Guard(Guard &&other) = default;
+  Guard &operator=(Guard &&other) = default;
+  virtual ~Guard() = default;
+  virtual void dismiss() {
+    std::abort();
+  }
+};
+
+template <class FunctionT>
+class LambdaGuard : public Guard {
+ public:
+  explicit LambdaGuard(const FunctionT &func) : func_(func) {
+  }
+  explicit LambdaGuard(FunctionT &&func) : func_(std::move(func)) {
+  }
+  LambdaGuard(const LambdaGuard &other) = delete;
+  LambdaGuard &operator=(const LambdaGuard &other) = delete;
+  LambdaGuard(LambdaGuard &&other) : func_(std::move(other.func_)), dismissed_(other.dismissed_) {
+    other.dismissed_ = true;
+  }
+  LambdaGuard &operator=(LambdaGuard &&other) = delete;
+
+  void dismiss() {
+    dismissed_ = true;
+  }
+
+  ~LambdaGuard() {
+    if (!dismissed_) {
+      func_();
+    }
+  }
+
+ private:
+  FunctionT func_;
+  bool dismissed_ = false;
+};
+
+template <class F>
+std::unique_ptr<Guard> create_lambda_guard(F &&f) {
+  return std::make_unique<LambdaGuard<F>>(std::forward<F>(f));
+}
+template <class F>
+std::shared_ptr<Guard> create_shared_lambda_guard(F &&f) {
+  return std::make_shared<LambdaGuard<F>>(std::forward<F>(f));
+}
+
+enum class ScopeExit {};
+template <class FunctionT>
+auto operator+(ScopeExit, FunctionT &&func) {
+  return LambdaGuard<std::decay_t<FunctionT>>(std::forward<FunctionT>(func));
+}
+
+}  // namespace td
+
+#define SCOPE_EXIT auto TD_CONCAT(SCOPE_EXIT_VAR_, __LINE__) = ::td::ScopeExit() + [&]()
diff --git a/libs/tdlib/td/tdutils/td/utils/SharedObjectPool.h b/libs/tdlib/td/tdutils/td/utils/SharedObjectPool.h
new file mode 100644
index 0000000000..dc8512b268
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/SharedObjectPool.h
@@ -0,0 +1,276 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/MpscLinkQueue.h"
+
+#include <atomic>
+#include <memory>
+#include <new>
+#include <utility>
+
+namespace td {
+
+namespace detail {
+class AtomicRefCnt {
+ public:
+  explicit AtomicRefCnt(uint64 cnt) : cnt_(cnt) {
+  }
+  void inc() {
+    cnt_.fetch_add(1, std::memory_order_relaxed);
+  }
+  bool dec() {
+    return cnt_.fetch_sub(1, std::memory_order_acq_rel) == 1;
+  }
+  uint64 value() const {
+    return cnt_.load(std::memory_order_relaxed);
+  }
+
+ private:
+  std::atomic<uint64> cnt_;
+};
+
+template <class DataT, class DeleterT>
+class SharedPtrRaw
+    : public DeleterT
+    , private MpscLinkQueueImpl::Node {
+ public:
+  explicit SharedPtrRaw(DeleterT deleter) : DeleterT(std::move(deleter)), ref_cnt_{0}, option_magic_(Magic) {
+  }
+
+  ~SharedPtrRaw() {
+    CHECK(use_cnt() == 0);
+    CHECK(option_magic_ == Magic);
+  }
+  template <class... ArgsT>
+  void init_data(ArgsT &&... args) {
+    new (&option_data_) DataT(std::forward<ArgsT>(args)...);
+  }
+  void destroy_data() {
+    option_data_.~DataT();
+    option_magic_ = Magic;
+  }
+  uint64 use_cnt() const {
+    return ref_cnt_.value();
+  }
+  void inc() {
+    ref_cnt_.inc();
+  }
+  bool dec() {
+    return ref_cnt_.dec();
+  }
+  DataT &data() {
+    return option_data_;
+  }
+  static SharedPtrRaw *from_mpsc_link_queue_node(MpscLinkQueueImpl::Node *node) {
+    return static_cast<SharedPtrRaw<DataT, DeleterT> *>(node);
+  }
+  MpscLinkQueueImpl::Node *to_mpsc_link_queue_node() {
+    return static_cast<MpscLinkQueueImpl::Node *>(this);
+  }
+
+ private:
+  AtomicRefCnt ref_cnt_;
+  enum { Magic = 0x732817a2 };
+  union {
+    DataT option_data_;
+    uint32 option_magic_;
+  };
+};
+
+template <class T, class DeleterT = std::default_delete<T>>
+class SharedPtr {
+ public:
+  using Raw = detail::SharedPtrRaw<T, DeleterT>;
+  SharedPtr() = default;
+  ~SharedPtr() {
+    if (!raw_) {
+      return;
+    }
+    reset();
+  }
+  explicit SharedPtr(Raw *raw) : raw_(raw) {
+    raw_->inc();
+  }
+  SharedPtr(const SharedPtr &other) : SharedPtr(other.raw_) {
+  }
+  SharedPtr &operator=(const SharedPtr &other) {
+    other.raw_->inc();
+    reset(other.raw_);
+    return *this;
+  }
+  SharedPtr(SharedPtr &&other) : raw_(other.raw_) {
+    other.raw_ = nullptr;
+  }
+  SharedPtr &operator=(SharedPtr &&other) {
+    reset(other.raw_);
+    other.raw_ = nullptr;
+    return *this;
+  }
+  bool empty() const {
+    return raw_ == nullptr;
+  }
+  explicit operator bool() const {
+    return !empty();
+  }
+  uint64 use_cnt() const {
+    if (!raw_) {
+      return 0;
+    }
+    return raw_->use_cnt();
+  }
+  T &operator*() const {
+    return raw_->data();
+  }
+  T *operator->() const {
+    return &raw_->data();
+  }
+
+  Raw *release() {
+    auto res = raw_;
+    raw_ = nullptr;
+    return res;
+  }
+
+  void reset(Raw *new_raw = nullptr) {
+    if (raw_ && raw_->dec()) {
+      raw_->destroy_data();
+      auto deleter = std::move(static_cast<DeleterT &>(*raw_));
+      deleter(raw_);
+    }
+    raw_ = new_raw;
+  }
+
+  template <class... ArgsT>
+  static SharedPtr<T, DeleterT> create(ArgsT &&... args) {
+    auto raw = std::make_unique<Raw>(DeleterT());
+    raw->init_data(std::forward<ArgsT>(args)...);
+    return SharedPtr<T, DeleterT>(raw.release());
+  }
+  template <class D, class... ArgsT>
+  static SharedPtr<T, DeleterT> create_with_deleter(D &&d, ArgsT &&... args) {
+    auto raw = std::make_unique<Raw>(std::forward<D>(d));
+    raw->init_data(std::forward<ArgsT>(args)...);
+    return SharedPtr<T, DeleterT>(raw.release());
+  }
+
+ private:
+  Raw *raw_{nullptr};
+};
+
+}  // namespace detail
+
+template <class DataT>
+class SharedObjectPool {
+  class Deleter;
+
+ public:
+  using Ptr = detail::SharedPtr<DataT, Deleter>;
+
+  SharedObjectPool() = default;
+  SharedObjectPool(const SharedObjectPool &other) = delete;
+  SharedObjectPool &operator=(const SharedObjectPool &other) = delete;
+  SharedObjectPool(SharedObjectPool &&other) = delete;
+  SharedObjectPool &operator=(SharedObjectPool &&other) = delete;
+  ~SharedObjectPool() {
+    free_queue_.pop_all(free_queue_reader_);
+    size_t free_cnt = 0;
+    while (free_queue_reader_.read()) {
+      free_cnt++;
+    }
+    CHECK(free_cnt == allocated_.size()) << free_cnt << " " << allocated_.size();
+  }
+
+  template <class... ArgsT>
+  Ptr alloc(ArgsT &&... args) {
+    auto *raw = alloc_raw();
+    raw->init_data(std::forward<ArgsT>(args)...);
+    return Ptr(raw);
+  }
+  size_t total_size() const {
+    return allocated_.size();
+  }
+  uint64 calc_free_size() {
+    free_queue_.pop_all(free_queue_reader_);
+    return free_queue_reader_.calc_size();
+  }
+
+  //non thread safe
+  template <class F>
+  void for_each(F &&f) {
+    for (auto &raw : allocated_) {
+      if (raw->use_cnt() > 0) {
+        f(raw->data());
+      }
+    }
+  }
+
+ private:
+  using Raw = typename Ptr::Raw;
+  Raw *alloc_raw() {
+    free_queue_.pop_all(free_queue_reader_);
+    auto *raw = free_queue_reader_.read().get();
+    if (raw) {
+      return raw;
+    }
+    allocated_.push_back(std::make_unique<Raw>(deleter()));
+    return allocated_.back().get();
+  }
+
+  void free_raw(Raw *raw) {
+    free_queue_.push(Node{raw});
+  }
+
+  class Node {
+   public:
+    Node() = default;
+    explicit Node(Raw *raw) : raw_(raw) {
+    }
+
+    MpscLinkQueueImpl::Node *to_mpsc_link_queue_node() {
+      return raw_->to_mpsc_link_queue_node();
+    }
+    static Node from_mpsc_link_queue_node(MpscLinkQueueImpl::Node *node) {
+      return Node{Raw::from_mpsc_link_queue_node(node)};
+    }
+    Raw *get() const {
+      return raw_;
+    }
+    explicit operator bool() const {
+      return raw_ != nullptr;
+    }
+
+   private:
+    Raw *raw_{nullptr};
+  };
+
+  class Deleter {
+   public:
+    explicit Deleter(SharedObjectPool<DataT> *pool) : pool_(pool) {
+    }
+    void operator()(Raw *raw) {
+      pool_->free_raw(raw);
+    };
+
+   private:
+    SharedObjectPool<DataT> *pool_;
+  };
+  friend class Deleter;
+
+  Deleter deleter() {
+    return Deleter(this);
+  }
+
+  std::vector<std::unique_ptr<Raw>> allocated_;
+  MpscLinkQueue<Node> free_queue_;
+  typename MpscLinkQueue<Node>::Reader free_queue_reader_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Slice-decl.h b/libs/tdlib/td/tdutils/td/utils/Slice-decl.h
new file mode 100644
index 0000000000..69b4a4ad21
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Slice-decl.h
@@ -0,0 +1,187 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+#include <cstring>
+#include <type_traits>
+
+namespace td {
+class Slice;
+
+class MutableSlice {
+  char *s_;
+  size_t len_;
+
+  struct private_tag {};
+
+ public:
+  MutableSlice();
+  MutableSlice(char *s, size_t len);
+  MutableSlice(unsigned char *s, size_t len);
+  MutableSlice(string &s);
+  template <class T>
+  explicit MutableSlice(T s, std::enable_if_t<std::is_same<char *, T>::value, private_tag> = {})
+      : MutableSlice(s, std::strlen(s)) {
+  }
+  MutableSlice(char *s, char *t);
+  MutableSlice(unsigned char *s, unsigned char *t);
+  template <size_t N>
+  constexpr MutableSlice(char (&a)[N]) = delete;
+
+  bool empty() const;
+  size_t size() const;
+
+  MutableSlice &remove_prefix(size_t prefix_len);
+  MutableSlice &remove_suffix(size_t suffix_len);
+  MutableSlice &truncate(size_t size);
+
+  MutableSlice copy() const;
+
+  char *data() const;
+  char *begin() const;
+  unsigned char *ubegin() const;
+  char *end() const;
+  unsigned char *uend() const;
+
+  string str() const;
+  MutableSlice substr(size_t from) const;
+  MutableSlice substr(size_t from, size_t size) const;
+  size_t find(char c) const;
+  size_t rfind(char c) const;
+
+  void copy_from(Slice from);
+
+  char &back();
+  char &operator[](size_t i);
+};
+
+class Slice {
+  const char *s_;
+  size_t len_;
+
+  struct private_tag {};
+
+ public:
+  Slice();
+  Slice(const MutableSlice &other);
+  Slice(const char *s, size_t len);
+  Slice(const unsigned char *s, size_t len);
+  Slice(const string &s);
+  template <class T>
+  explicit Slice(T s, std::enable_if_t<std::is_same<char *, std::remove_const_t<T>>::value, private_tag> = {})
+      : Slice(s, std::strlen(s)) {
+  }
+  template <class T>
+  explicit Slice(T s, std::enable_if_t<std::is_same<const char *, std::remove_const_t<T>>::value, private_tag> = {})
+      : Slice(s, std::strlen(s)) {
+  }
+  Slice(const char *s, const char *t);
+  Slice(const unsigned char *s, const unsigned char *t);
+
+  template <size_t N>
+  constexpr Slice(char (&a)[N]) = delete;
+
+  template <size_t N>
+  constexpr Slice(const char (&a)[N]) : s_(a), len_(N - 1) {
+  }
+
+  bool empty() const;
+  size_t size() const;
+
+  Slice &remove_prefix(size_t prefix_len);
+  Slice &remove_suffix(size_t suffix_len);
+  Slice &truncate(size_t size);
+
+  Slice copy() const;
+
+  const char *data() const;
+  const char *begin() const;
+  const unsigned char *ubegin() const;
+  const char *end() const;
+  const unsigned char *uend() const;
+
+  string str() const;
+  Slice substr(size_t from) const;
+  Slice substr(size_t from, size_t size) const;
+  size_t find(char c) const;
+  size_t rfind(char c) const;
+
+  char back() const;
+  char operator[](size_t i) const;
+};
+
+bool operator==(const Slice &a, const Slice &b);
+bool operator!=(const Slice &a, const Slice &b);
+
+class MutableCSlice : public MutableSlice {
+  struct private_tag {};
+
+  MutableSlice &remove_suffix(size_t suffix_len) = delete;
+  MutableSlice &truncate(size_t size) = delete;
+
+ public:
+  MutableCSlice() = delete;
+  MutableCSlice(string &s) : MutableSlice(s) {
+  }
+  template <class T>
+  explicit MutableCSlice(T s, std::enable_if_t<std::is_same<char *, T>::value, private_tag> = {}) : MutableSlice(s) {
+  }
+  MutableCSlice(char *s, char *t);
+
+  template <size_t N>
+  constexpr MutableCSlice(char (&a)[N]) = delete;
+
+  const char *c_str() const {
+    return begin();
+  }
+};
+
+class CSlice : public Slice {
+  struct private_tag {};
+
+  Slice &remove_suffix(size_t suffix_len) = delete;
+  Slice &truncate(size_t size) = delete;
+
+ public:
+  explicit CSlice(const MutableSlice &other) : Slice(other) {
+  }
+  CSlice(const MutableCSlice &other) : Slice(other.begin(), other.size()) {
+  }
+  CSlice(const string &s) : Slice(s) {
+  }
+  template <class T>
+  explicit CSlice(T s, std::enable_if_t<std::is_same<char *, std::remove_const_t<T>>::value, private_tag> = {})
+      : Slice(s) {
+  }
+  template <class T>
+  explicit CSlice(T s, std::enable_if_t<std::is_same<const char *, std::remove_const_t<T>>::value, private_tag> = {})
+      : Slice(s) {
+  }
+  CSlice(const char *s, const char *t);
+
+  template <size_t N>
+  constexpr CSlice(char (&a)[N]) = delete;
+
+  template <size_t N>
+  constexpr CSlice(const char (&a)[N]) : Slice(a) {
+  }
+
+  CSlice() : CSlice("") {
+  }
+
+  const char *c_str() const {
+    return begin();
+  }
+};
+
+struct SliceHash {
+  std::size_t operator()(Slice slice) const;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Slice.h b/libs/tdlib/td/tdutils/td/utils/Slice.h
new file mode 100644
index 0000000000..a9bc6a7551
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Slice.h
@@ -0,0 +1,275 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/Slice-decl.h"
+
+#include "td/utils/logging.h"
+
+#include <cstring>
+
+namespace td {
+/*** MutableSlice ***/
+inline MutableSlice::MutableSlice() : MutableSlice(const_cast<char *>(""), static_cast<size_t>(0)) {
+}
+
+inline MutableSlice::MutableSlice(char *s, size_t len) : s_(s), len_(len) {
+  CHECK(s_ != nullptr);
+}
+
+inline MutableSlice::MutableSlice(unsigned char *s, size_t len) : s_(reinterpret_cast<char *>(s)), len_(len) {
+  CHECK(s_ != nullptr);
+}
+
+inline MutableSlice::MutableSlice(string &s) : MutableSlice(&s[0], s.size()) {
+}
+
+inline MutableSlice::MutableSlice(char *s, char *t) : MutableSlice(s, t - s) {
+}
+
+inline MutableSlice::MutableSlice(unsigned char *s, unsigned char *t) : MutableSlice(s, t - s) {
+}
+
+inline size_t MutableSlice::size() const {
+  return len_;
+}
+
+inline MutableSlice &MutableSlice::remove_prefix(size_t prefix_len) {
+  CHECK(prefix_len <= len_);
+  s_ += prefix_len;
+  len_ -= prefix_len;
+  return *this;
+}
+inline MutableSlice &MutableSlice::remove_suffix(size_t suffix_len) {
+  CHECK(suffix_len <= len_);
+  len_ -= suffix_len;
+  return *this;
+}
+
+inline MutableSlice &MutableSlice::truncate(size_t size) {
+  if (len_ > size) {
+    len_ = size;
+  }
+  return *this;
+}
+
+inline MutableSlice MutableSlice::copy() const {
+  return *this;
+}
+
+inline bool MutableSlice::empty() const {
+  return len_ == 0;
+}
+
+inline char *MutableSlice::data() const {
+  return s_;
+}
+
+inline char *MutableSlice::begin() const {
+  return s_;
+}
+
+inline unsigned char *MutableSlice::ubegin() const {
+  return reinterpret_cast<unsigned char *>(s_);
+}
+
+inline char *MutableSlice::end() const {
+  return s_ + len_;
+}
+
+inline unsigned char *MutableSlice::uend() const {
+  return reinterpret_cast<unsigned char *>(s_) + len_;
+}
+
+inline string MutableSlice::str() const {
+  return string(begin(), size());
+}
+
+inline MutableSlice MutableSlice::substr(size_t from) const {
+  CHECK(from <= len_);
+  return MutableSlice(s_ + from, len_ - from);
+}
+inline MutableSlice MutableSlice::substr(size_t from, size_t size) const {
+  CHECK(from <= len_);
+  return MutableSlice(s_ + from, min(size, len_ - from));
+}
+
+inline size_t MutableSlice::find(char c) const {
+  for (size_t pos = 0; pos < len_; pos++) {
+    if (s_[pos] == c) {
+      return pos;
+    }
+  }
+  return static_cast<size_t>(-1);
+}
+
+inline size_t MutableSlice::rfind(char c) const {
+  for (size_t pos = len_; pos-- > 0;) {
+    if (s_[pos] == c) {
+      return pos;
+    }
+  }
+  return static_cast<size_t>(-1);
+}
+
+inline void MutableSlice::copy_from(Slice from) {
+  CHECK(size() >= from.size());
+  std::memcpy(ubegin(), from.ubegin(), from.size());
+}
+
+inline char &MutableSlice::back() {
+  CHECK(1 <= len_);
+  return s_[len_ - 1];
+}
+
+inline char &MutableSlice::operator[](size_t i) {
+  return s_[i];
+}
+
+/*** Slice ***/
+inline Slice::Slice() : Slice("", static_cast<size_t>(0)) {
+}
+
+inline Slice::Slice(const MutableSlice &other) : Slice(other.begin(), other.size()) {
+}
+
+inline Slice::Slice(const char *s, size_t len) : s_(s), len_(len) {
+  CHECK(s_ != nullptr);
+}
+
+inline Slice::Slice(const unsigned char *s, size_t len) : s_(reinterpret_cast<const char *>(s)), len_(len) {
+  CHECK(s_ != nullptr);
+}
+
+inline Slice::Slice(const string &s) : Slice(s.c_str(), s.size()) {
+}
+
+inline Slice::Slice(const char *s, const char *t) : Slice(s, t - s) {
+}
+
+inline Slice::Slice(const unsigned char *s, const unsigned char *t) : Slice(s, t - s) {
+}
+
+inline size_t Slice::size() const {
+  return len_;
+}
+
+inline Slice &Slice::remove_prefix(size_t prefix_len) {
+  CHECK(prefix_len <= len_);
+  s_ += prefix_len;
+  len_ -= prefix_len;
+  return *this;
+}
+
+inline Slice &Slice::remove_suffix(size_t suffix_len) {
+  CHECK(suffix_len <= len_);
+  len_ -= suffix_len;
+  return *this;
+}
+
+inline Slice &Slice::truncate(size_t size) {
+  if (len_ > size) {
+    len_ = size;
+  }
+  return *this;
+}
+
+inline Slice Slice::copy() const {
+  return *this;
+}
+
+inline bool Slice::empty() const {
+  return len_ == 0;
+}
+
+inline const char *Slice::data() const {
+  return s_;
+}
+
+inline const char *Slice::begin() const {
+  return s_;
+}
+
+inline const unsigned char *Slice::ubegin() const {
+  return reinterpret_cast<const unsigned char *>(s_);
+}
+
+inline const char *Slice::end() const {
+  return s_ + len_;
+}
+
+inline const unsigned char *Slice::uend() const {
+  return reinterpret_cast<const unsigned char *>(s_) + len_;
+}
+
+inline string Slice::str() const {
+  return string(begin(), size());
+}
+
+inline Slice Slice::substr(size_t from) const {
+  CHECK(from <= len_);
+  return Slice(s_ + from, len_ - from);
+}
+inline Slice Slice::substr(size_t from, size_t size) const {
+  CHECK(from <= len_);
+  return Slice(s_ + from, min(size, len_ - from));
+}
+
+inline size_t Slice::find(char c) const {
+  for (size_t pos = 0; pos < len_; pos++) {
+    if (s_[pos] == c) {
+      return pos;
+    }
+  }
+  return static_cast<size_t>(-1);
+}
+
+inline size_t Slice::rfind(char c) const {
+  for (size_t pos = len_; pos-- > 0;) {
+    if (s_[pos] == c) {
+      return pos;
+    }
+  }
+  return static_cast<size_t>(-1);
+}
+
+inline char Slice::back() const {
+  CHECK(1 <= len_);
+  return s_[len_ - 1];
+}
+
+inline char Slice::operator[](size_t i) const {
+  return s_[i];
+}
+
+inline bool operator==(const Slice &a, const Slice &b) {
+  return a.size() == b.size() && std::memcmp(a.data(), b.data(), a.size()) == 0;
+}
+
+inline bool operator!=(const Slice &a, const Slice &b) {
+  return !(a == b);
+}
+
+inline MutableCSlice::MutableCSlice(char *s, char *t) : MutableSlice(s, t) {
+  CHECK(*t == '\0');
+}
+
+inline CSlice::CSlice(const char *s, const char *t) : Slice(s, t) {
+  CHECK(*t == '\0');
+}
+
+inline std::size_t SliceHash::operator()(Slice slice) const {
+  // simple string hash
+  std::size_t result = 0;
+  constexpr std::size_t MUL = 123456789;
+  for (auto c : slice) {
+    result = result * MUL + c;
+  }
+  return result;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/SpinLock.h b/libs/tdlib/td/tdutils/td/utils/SpinLock.h
new file mode 100644
index 0000000000..d726b0b2f6
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/SpinLock.h
@@ -0,0 +1,58 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/thread.h"
+
+#include <atomic>
+
+namespace td {
+
+class SpinLock {
+  struct Unlock {
+    void operator()(SpinLock *ptr) {
+      ptr->unlock();
+    }
+  };
+
+  class InfBackoff {
+    int cnt = 0;
+
+   public:
+    bool next() {
+      cnt++;
+      if (cnt < 50) {
+        return true;
+      } else {
+        td::this_thread::yield();
+        return true;
+      }
+    }
+  };
+
+ public:
+  using Lock = std::unique_ptr<SpinLock, Unlock>;
+
+  Lock lock() {
+    InfBackoff backoff;
+    while (!try_lock()) {
+      backoff.next();
+    }
+    return Lock(this);
+  }
+  bool try_lock() {
+    return !flag_.test_and_set(std::memory_order_acquire);
+  }
+
+ private:
+  std::atomic_flag flag_ = ATOMIC_FLAG_INIT;
+  void unlock() {
+    flag_.clear(std::memory_order_release);
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/StackAllocator.cpp b/libs/tdlib/td/tdutils/td/utils/StackAllocator.cpp
new file mode 100644
index 0000000000..4db905368b
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/StackAllocator.cpp
@@ -0,0 +1,18 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/StackAllocator.h"
+
+#include "td/utils/port/thread_local.h"
+
+namespace td {
+
+StackAllocator::Impl &StackAllocator::impl() {
+  static TD_THREAD_LOCAL StackAllocator::Impl *impl;  // static zero-initialized
+  init_thread_local<Impl>(impl);
+  return *impl;
+}
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/StackAllocator.h b/libs/tdlib/td/tdutils/td/utils/StackAllocator.h
new file mode 100644
index 0000000000..d2399b9526
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/StackAllocator.h
@@ -0,0 +1,82 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/MovableValue.h"
+#include "td/utils/Slice-decl.h"
+
+#include <array>
+#include <cstdlib>
+
+namespace td {
+
+class StackAllocator {
+  class Deleter {
+   public:
+    void operator()(char *ptr) {
+      free_ptr(ptr);
+    }
+  };
+
+  // TODO: alloc memory with mmap and unload unused pages
+  // memory still can be corrupted, but it is better than explicit free function
+  // TODO: use pointer that can't be even copied
+  using PtrImpl = std::unique_ptr<char, Deleter>;
+  class Ptr {
+   public:
+    Ptr(char *ptr, size_t size) : ptr_(ptr), size_(size) {
+    }
+
+    MutableSlice as_slice() const {
+      return MutableSlice(ptr_.get(), size_.get());
+    }
+
+   private:
+    PtrImpl ptr_;
+    MovableValue<size_t> size_;
+  };
+
+  static void free_ptr(char *ptr) {
+    impl().free_ptr(ptr);
+  }
+
+  struct Impl {
+    static const size_t MEM_SIZE = 1024 * 1024;
+    std::array<char, MEM_SIZE> mem;
+
+    size_t pos{0};
+    char *alloc(size_t size) {
+      if (size == 0) {
+        size = 1;
+      }
+      char *res = mem.data() + pos;
+      size = (size + 7) & -8;
+      pos += size;
+      if (pos > MEM_SIZE) {
+        std::abort();  // memory is over
+      }
+      return res;
+    }
+    void free_ptr(char *ptr) {
+      size_t new_pos = ptr - mem.data();
+      if (new_pos >= pos) {
+        std::abort();  // shouldn't happen
+      }
+      pos = new_pos;
+    }
+  };
+
+  static Impl &impl();
+
+ public:
+  static Ptr alloc(size_t size) {
+    return Ptr(impl().alloc(size), size);
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Status.cpp b/libs/tdlib/td/tdutils/td/utils/Status.cpp
new file mode 100644
index 0000000000..b8bb169e60
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Status.cpp
@@ -0,0 +1,54 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/Status.h"
+
+#if TD_PORT_WINDOWS
+#include "td/utils/port/wstring_convert.h"
+#endif
+
+#if TD_PORT_POSIX
+#include "td/utils/port/thread_local.h"
+
+#include <string.h>
+
+#include <cstring>
+#endif
+
+namespace td {
+
+#if TD_PORT_POSIX
+CSlice strerror_safe(int code) {
+  const size_t size = 1000;
+
+  static TD_THREAD_LOCAL char *buf;
+  init_thread_local<char[]>(buf, size);
+
+#if !defined(__GLIBC__) || ((_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600) && !_GNU_SOURCE)
+  strerror_r(code, buf, size);
+  return CSlice(buf, buf + std::strlen(buf));
+#else
+  return CSlice(strerror_r(code, buf, size));
+#endif
+}
+#endif
+
+#if TD_PORT_WINDOWS
+string winerror_to_string(int code) {
+  const size_t size = 1000;
+  wchar_t wbuf[size];
+  auto res_size = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, nullptr, code, 0, wbuf, size - 1, nullptr);
+  if (res_size == 0) {
+    return "Unknown windows error";
+  }
+  while (res_size != 0 && (wbuf[res_size - 1] == '\n' || wbuf[res_size - 1] == '\r')) {
+    res_size--;
+  }
+  return from_wstring(wbuf, res_size).ok();
+}
+#endif
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Status.h b/libs/tdlib/td/tdutils/td/utils/Status.h
new file mode 100644
index 0000000000..8ef2846df1
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Status.h
@@ -0,0 +1,458 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Slice.h"
+#include "td/utils/StackAllocator.h"
+#include "td/utils/StringBuilder.h"
+
+#include <cerrno>
+#include <cstring>
+#include <new>
+#include <utility>
+
+#define TRY_STATUS(status)               \
+  {                                      \
+    auto try_status = (status);          \
+    if (try_status.is_error()) {         \
+      return try_status.move_as_error(); \
+    }                                    \
+  }
+#define TRY_RESULT(name, result) TRY_RESULT_IMPL(TD_CONCAT(TD_CONCAT(r_, name), __LINE__), name, result)
+
+#define TRY_RESULT_IMPL(r_name, name, result) \
+  auto r_name = (result);                     \
+  if (r_name.is_error()) {                    \
+    return r_name.move_as_error();            \
+  }                                           \
+  auto name = r_name.move_as_ok();
+
+#define LOG_STATUS(status)                      \
+  {                                             \
+    auto log_status = (status);                 \
+    if (log_status.is_error()) {                \
+      LOG(ERROR) << log_status.move_as_error(); \
+    }                                           \
+  }
+
+#ifndef TD_STATUS_NO_ENSURE
+#define ensure() ensure_impl(__FILE__, __LINE__)
+#define ensure_error() ensure_error_impl(__FILE__, __LINE__)
+#endif
+
+#if TD_PORT_POSIX
+#define OS_ERROR(message)                                    \
+  [&]() {                                                    \
+    auto saved_errno = errno;                                \
+    return ::td::Status::PosixError(saved_errno, (message)); \
+  }()
+#define OS_SOCKET_ERROR(message) OS_ERROR(message)
+#elif TD_PORT_WINDOWS
+#define OS_ERROR(message)                                      \
+  [&]() {                                                      \
+    auto saved_error = ::GetLastError();                       \
+    return ::td::Status::WindowsError(saved_error, (message)); \
+  }()
+#define OS_SOCKET_ERROR(message)                               \
+  [&]() {                                                      \
+    auto saved_error = ::WSAGetLastError();                    \
+    return ::td::Status::WindowsError(saved_error, (message)); \
+  }()
+#endif
+
+namespace td {
+
+#if TD_PORT_POSIX
+CSlice strerror_safe(int code);
+#endif
+
+#if TD_PORT_WINDOWS
+string winerror_to_string(int code);
+#endif
+
+class Status {
+  enum class ErrorType : int8 { general, os };
+
+ public:
+  Status() = default;
+
+  bool operator==(const Status &other) const {
+    if (get_info().static_flag) {
+      return ptr_ == other.ptr_;
+    }
+    return false;
+  }
+
+  Status clone() const TD_WARN_UNUSED_RESULT {
+    if (is_ok()) {
+      return Status();
+    }
+    auto info = get_info();
+    if (info.static_flag) {
+      return clone_static();
+    }
+    return Status(false, info.error_type, info.error_code, message());
+  }
+
+  static Status OK() TD_WARN_UNUSED_RESULT {
+    return Status();
+  }
+
+  static Status Error(int err, Slice message = Slice()) TD_WARN_UNUSED_RESULT {
+    return Status(false, ErrorType::general, err, message);
+  }
+
+  static Status Error(Slice message) TD_WARN_UNUSED_RESULT {
+    return Error(0, message);
+  }
+
+#if TD_PORT_WINDOWS
+  static Status WindowsError(int saved_error, Slice message) TD_WARN_UNUSED_RESULT {
+    return Status(false, ErrorType::os, saved_error, message);
+  }
+#endif
+
+#if TD_PORT_POSIX
+  static Status PosixError(int32 saved_errno, Slice message) TD_WARN_UNUSED_RESULT {
+    return Status(false, ErrorType::os, saved_errno, message);
+  }
+#endif
+
+  static Status Error() TD_WARN_UNUSED_RESULT {
+    return Error<0>();
+  }
+
+  template <int Code>
+  static Status Error() {
+    static Status status(true, ErrorType::general, Code, "");
+    return status.clone_static();
+  }
+
+  static Status InvalidId() TD_WARN_UNUSED_RESULT {
+    static Status status(true, ErrorType::general, 0, "Invalid Id");
+    return status.clone_static();
+  }
+
+  static Status Hangup() TD_WARN_UNUSED_RESULT {
+    static Status status(true, ErrorType::general, 0, "Hangup");
+    return status.clone_static();
+  }
+
+  StringBuilder &print(StringBuilder &sb) const {
+    if (is_ok()) {
+      return sb << "OK";
+    }
+    Info info = get_info();
+    switch (info.error_type) {
+      case ErrorType::general:
+        sb << "[Error";
+        break;
+      case ErrorType::os:
+#if TD_PORT_POSIX
+        sb << "[PosixError : " << strerror_safe(info.error_code);
+#elif TD_PORT_WINDOWS
+        sb << "[WindowsError : " << winerror_to_string(info.error_code);
+#endif
+        break;
+      default:
+        LOG(FATAL) << "Unknown status type: " << static_cast<int8>(info.error_type);
+        UNREACHABLE();
+        break;
+    }
+    sb << " : " << code() << " : " << message() << "]";
+    return sb;
+  }
+
+  string to_string() const {
+    auto buf = StackAllocator::alloc(4096);
+    StringBuilder sb(buf.as_slice());
+    print(sb);
+    return sb.as_cslice().str();
+  }
+
+  // Default interface
+  bool is_ok() const TD_WARN_UNUSED_RESULT {
+    return !is_error();
+  }
+
+  bool is_error() const TD_WARN_UNUSED_RESULT {
+    return ptr_ != nullptr;
+  }
+
+  void ensure_impl(CSlice file_name, int line) const {
+    if (!is_ok()) {
+      LOG(FATAL) << "Unexpexted Status " << to_string() << " in file " << file_name << " at line " << line;
+    }
+  }
+  void ensure_error_impl(CSlice file_name, int line) const {
+    if (is_ok()) {
+      LOG(FATAL) << "Unexpected Status::OK in file " << file_name << " at line " << line;
+    }
+  }
+
+  void ignore() const {
+    // nop
+  }
+
+  int32 code() const {
+    if (is_ok()) {
+      return 0;
+    }
+    return get_info().error_code;
+  }
+
+  CSlice message() const {
+    if (is_ok()) {
+      return CSlice("OK");
+    }
+    return CSlice(ptr_.get() + sizeof(Info));
+  }
+
+  string public_message() const {
+    if (is_ok()) {
+      return "OK";
+    }
+    Info info = get_info();
+    switch (info.error_type) {
+      case ErrorType::general:
+        return message().str();
+      case ErrorType::os:
+#if TD_PORT_POSIX
+        return strerror_safe(info.error_code).str();
+#elif TD_PORT_WINDOWS
+        return winerror_to_string(info.error_code);
+#endif
+      default:
+        LOG(FATAL) << "Unknown status type: " << static_cast<int8>(info.error_type);
+        UNREACHABLE();
+        return "";
+    }
+  }
+
+  const Status &error() const {
+    return *this;
+  }
+
+  Status move() TD_WARN_UNUSED_RESULT {
+    return std::move(*this);
+  }
+
+  Status move_as_error() TD_WARN_UNUSED_RESULT {
+    return std::move(*this);
+  }
+
+ private:
+  struct Info {
+    bool static_flag : 1;
+    signed int error_code : 23;
+    ErrorType error_type;
+  };
+
+  struct Deleter {
+    void operator()(char *ptr) {
+      if (!get_info(ptr).static_flag) {
+        delete[] ptr;
+      }
+    }
+  };
+  std::unique_ptr<char[], Deleter> ptr_;
+
+  Status(Info info, Slice message) {
+    size_t size = sizeof(Info) + message.size() + 1;
+    ptr_ = std::unique_ptr<char[], Deleter>(new char[size]);
+    char *ptr = ptr_.get();
+    reinterpret_cast<Info *>(ptr)[0] = info;
+    ptr += sizeof(Info);
+    std::memcpy(ptr, message.begin(), message.size());
+    ptr += message.size();
+    *ptr = 0;
+  }
+
+  Status(bool static_flag, ErrorType error_type, int error_code, Slice message)
+      : Status(to_info(static_flag, error_type, error_code), message) {
+  }
+
+  Status clone_static() const TD_WARN_UNUSED_RESULT {
+    CHECK(is_ok() || get_info().static_flag);
+    Status result;
+    result.ptr_ = std::unique_ptr<char[], Deleter>(ptr_.get());
+    return result;
+  }
+
+  static Info to_info(bool static_flag, ErrorType error_type, int error_code) {
+    const int MIN_ERROR_CODE = -(1 << 22) + 1;
+    const int MAX_ERROR_CODE = (1 << 22) - 1;
+    Info tmp;
+    tmp.static_flag = static_flag;
+    tmp.error_type = error_type;
+
+    if (error_code < MIN_ERROR_CODE) {
+      LOG(ERROR) << "Error code value is altered from " << error_code;
+      error_code = MIN_ERROR_CODE;
+    }
+    if (error_code > MAX_ERROR_CODE) {
+      LOG(ERROR) << "Error code value is altered from " << error_code;
+      error_code = MAX_ERROR_CODE;
+    }
+
+#if TD_GCC
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wconversion"
+#endif
+    tmp.error_code = error_code;
+#if TD_GCC
+#pragma GCC diagnostic pop
+#endif
+    CHECK(error_code == tmp.error_code);
+    return tmp;
+  }
+
+  Info get_info() const {
+    return get_info(ptr_.get());
+  }
+  static Info get_info(char *ptr) {
+    return reinterpret_cast<Info *>(ptr)[0];
+  }
+};
+
+template <class T = Unit>
+class Result {
+ public:
+  Result() : status_(Status::Error()) {
+  }
+  template <class S>
+  Result(S &&x) : status_(), value_(std::forward<S>(x)) {
+  }
+  Result(Status &&status) : status_(std::move(status)) {
+    CHECK(status_.is_error());
+  }
+  Result(const Result &) = delete;
+  Result &operator=(const Result &) = delete;
+  Result(Result &&other) : status_(std::move(other.status_)) {
+    if (status_.is_ok()) {
+      new (&value_) T(std::move(other.value_));
+      other.value_.~T();
+    }
+    other.status_ = Status::Error();
+  }
+  Result &operator=(Result &&other) {
+    if (status_.is_ok()) {
+      value_.~T();
+    }
+    if (other.status_.is_ok()) {
+#if TD_GCC
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#endif
+      new (&value_) T(std::move(other.value_));
+#if TD_GCC
+#pragma GCC diagnostic pop
+#endif
+      other.value_.~T();
+    }
+    status_ = std::move(other.status_);
+    other.status_ = Status::Error();
+    return *this;
+  }
+  ~Result() {
+    if (status_.is_ok()) {
+      value_.~T();
+    }
+  }
+
+  void ensure_impl(CSlice file_name, int line) const {
+    status_.ensure_impl(file_name, line);
+  }
+  void ensure_error_impl(CSlice file_name, int line) const {
+    status_.ensure_error_impl(file_name, line);
+  }
+  void ignore() const {
+    status_.ignore();
+  }
+  bool is_ok() const {
+    return status_.is_ok();
+  }
+  bool is_error() const {
+    return status_.is_error();
+  }
+  const Status &error() const {
+    CHECK(status_.is_error());
+    return status_;
+  }
+  Status move_as_error() TD_WARN_UNUSED_RESULT {
+    CHECK(status_.is_error());
+    SCOPE_EXIT {
+      status_ = Status::Error();
+    };
+    return std::move(status_);
+  }
+  const T &ok() const {
+    CHECK(status_.is_ok()) << status_;
+    return value_;
+  }
+  T &ok_ref() {
+    CHECK(status_.is_ok()) << status_;
+    return value_;
+  }
+  T move_as_ok() {
+    CHECK(status_.is_ok()) << status_;
+    return std::move(value_);
+  }
+
+  Result<T> clone() const TD_WARN_UNUSED_RESULT {
+    if (is_ok()) {
+      return Result<T>(ok());  // TODO: return clone(ok());
+    }
+    return error().clone();
+  }
+  void clear() {
+    *this = Result<T>();
+  }
+
+ private:
+  Status status_;
+  union {
+    T value_;
+  };
+};
+
+template <>
+inline Result<Unit>::Result(Status &&status) : status_(std::move(status)) {
+  // no assert
+}
+
+inline StringBuilder &operator<<(StringBuilder &string_builder, const Status &status) {
+  return status.print(string_builder);
+}
+
+namespace detail {
+
+class SlicifySafe {
+ public:
+  Result<CSlice> operator&(Logger &logger) {
+    if (logger.is_error()) {
+      return Status::Error("Buffer overflow");
+    }
+    return logger.as_cslice();
+  }
+};
+
+class StringifySafe {
+ public:
+  Result<string> operator&(Logger &logger) {
+    if (logger.is_error()) {
+      return Status::Error("Buffer overflow");
+    }
+    return logger.as_cslice().str();
+  }
+};
+
+}  // namespace detail
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Storer.h b/libs/tdlib/td/tdutils/td/utils/Storer.h
new file mode 100644
index 0000000000..91750dcd44
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Storer.h
@@ -0,0 +1,86 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/utils/StorerBase.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+#include "td/utils/tl_storers.h"
+
+#include <cstring>
+#include <limits>
+
+namespace td {
+class SliceStorer : public Storer {
+  Slice slice;
+
+ public:
+  explicit SliceStorer(Slice slice) : slice(slice) {
+  }
+  size_t size() const override {
+    return slice.size();
+  }
+  size_t store(uint8 *ptr) const override {
+    std::memcpy(ptr, slice.ubegin(), slice.size());
+    return slice.size();
+  }
+};
+
+inline SliceStorer create_storer(Slice slice) {
+  return SliceStorer(slice);
+}
+
+class ConcatStorer : public Storer {
+  const Storer &a_;
+  const Storer &b_;
+
+ public:
+  ConcatStorer(const Storer &a, const Storer &b) : a_(a), b_(b) {
+  }
+
+  size_t size() const override {
+    return a_.size() + b_.size();
+  }
+
+  size_t store(uint8 *ptr) const override {
+    uint8 *ptr_save = ptr;
+    ptr += a_.store(ptr);
+    ptr += b_.store(ptr);
+    return ptr - ptr_save;
+  }
+};
+
+inline ConcatStorer create_storer(const Storer &a, const Storer &b) {
+  return ConcatStorer(a, b);
+}
+
+template <class T>
+class DefaultStorer : public Storer {
+ public:
+  explicit DefaultStorer(const T &object) : object_(object) {
+  }
+  size_t size() const override {
+    if (size_ == std::numeric_limits<size_t>::max()) {
+      size_ = tl_calc_length(object_);
+    }
+    return size_;
+  }
+  size_t store(uint8 *ptr) const override {
+    return tl_store_unsafe(object_, ptr);
+  }
+
+ private:
+  mutable size_t size_ = std::numeric_limits<size_t>::max();
+  const T &object_;
+};
+
+template <class T>
+DefaultStorer<T> create_default_storer(const T &from) {
+  return DefaultStorer<T>(from);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/StorerBase.h b/libs/tdlib/td/tdutils/td/utils/StorerBase.h
new file mode 100644
index 0000000000..e6fea28e16
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/StorerBase.h
@@ -0,0 +1,25 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/int_types.h"
+
+namespace td {
+
+class Storer {
+ public:
+  Storer() = default;
+  Storer(const Storer &) = delete;
+  Storer &operator=(const Storer &) = delete;
+  Storer(Storer &&) = default;
+  Storer &operator=(Storer &&) = default;
+  virtual ~Storer() = default;
+  virtual size_t size() const = 0;
+  virtual size_t store(uint8 *ptr) const = 0;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/StringBuilder.cpp b/libs/tdlib/td/tdutils/td/utils/StringBuilder.cpp
new file mode 100644
index 0000000000..ce64bbc9a6
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/StringBuilder.cpp
@@ -0,0 +1,102 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/StringBuilder.h"
+
+#include "td/utils/misc.h"
+#include "td/utils/port/thread_local.h"
+
+#include <cstdio>
+#include <locale>
+#include <sstream>
+
+namespace td {
+
+// TODO: optimize
+StringBuilder &StringBuilder::operator<<(int x) {
+  if (unlikely(end_ptr_ < current_ptr_)) {
+    return on_error();
+  }
+  current_ptr_ += std::snprintf(current_ptr_, reserved_size, "%d", x);
+  return *this;
+}
+
+StringBuilder &StringBuilder::operator<<(unsigned int x) {
+  if (unlikely(end_ptr_ < current_ptr_)) {
+    return on_error();
+  }
+  current_ptr_ += std::snprintf(current_ptr_, reserved_size, "%u", x);
+  return *this;
+}
+
+StringBuilder &StringBuilder::operator<<(long int x) {
+  if (unlikely(end_ptr_ < current_ptr_)) {
+    return on_error();
+  }
+  current_ptr_ += std::snprintf(current_ptr_, reserved_size, "%ld", x);
+  return *this;
+}
+
+StringBuilder &StringBuilder::operator<<(long unsigned int x) {
+  if (unlikely(end_ptr_ < current_ptr_)) {
+    return on_error();
+  }
+  current_ptr_ += std::snprintf(current_ptr_, reserved_size, "%lu", x);
+  return *this;
+}
+
+StringBuilder &StringBuilder::operator<<(long long int x) {
+  if (unlikely(end_ptr_ < current_ptr_)) {
+    return on_error();
+  }
+  current_ptr_ += std::snprintf(current_ptr_, reserved_size, "%lld", x);
+  return *this;
+}
+
+StringBuilder &StringBuilder::operator<<(long long unsigned int x) {
+  if (unlikely(end_ptr_ < current_ptr_)) {
+    return on_error();
+  }
+  current_ptr_ += std::snprintf(current_ptr_, reserved_size, "%llu", x);
+  return *this;
+}
+
+StringBuilder &StringBuilder::operator<<(FixedDouble x) {
+  if (unlikely(end_ptr_ < current_ptr_)) {
+    return on_error();
+  }
+
+  static TD_THREAD_LOCAL std::stringstream *ss;
+  if (init_thread_local<std::stringstream>(ss)) {
+    ss->imbue(std::locale::classic());
+    ss->setf(std::ios_base::fixed, std::ios_base::floatfield);
+  } else {
+    ss->str(std::string());
+    ss->clear();
+  }
+  ss->precision(x.precision);
+  *ss << x.d;
+
+  int len = narrow_cast<int>(static_cast<std::streamoff>(ss->tellp()));
+  auto left = end_ptr_ + reserved_size - current_ptr_;
+  if (unlikely(len >= left)) {
+    error_flag_ = true;
+    len = left ? narrow_cast<int>(left - 1) : 0;
+  }
+  ss->read(current_ptr_, len);
+  current_ptr_ += len;
+  return *this;
+}
+
+StringBuilder &StringBuilder::operator<<(const void *ptr) {
+  if (unlikely(end_ptr_ < current_ptr_)) {
+    return on_error();
+  }
+  current_ptr_ += std::snprintf(current_ptr_, reserved_size, "%p", ptr);
+  return *this;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/StringBuilder.h b/libs/tdlib/td/tdutils/td/utils/StringBuilder.h
new file mode 100644
index 0000000000..a6345a9273
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/StringBuilder.h
@@ -0,0 +1,138 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/Slice-decl.h"
+#include "td/utils/StackAllocator.h"
+
+#include <cstdlib>
+#include <cstring>
+#include <type_traits>
+
+namespace td {
+
+class StringBuilder {
+ public:
+  explicit StringBuilder(MutableSlice slice)
+      : begin_ptr_(slice.begin()), current_ptr_(begin_ptr_), end_ptr_(slice.end() - reserved_size) {
+    if (slice.size() <= reserved_size) {
+      std::abort();  // shouldn't happen
+    }
+  }
+
+  void clear() {
+    current_ptr_ = begin_ptr_;
+    error_flag_ = false;
+  }
+
+  MutableCSlice as_cslice() {
+    if (current_ptr_ >= end_ptr_ + reserved_size) {
+      std::abort();  // shouldn't happen
+    }
+    *current_ptr_ = 0;
+    return MutableCSlice(begin_ptr_, current_ptr_);
+  }
+
+  bool is_error() const {
+    return error_flag_;
+  }
+
+  StringBuilder &operator<<(const char *str) {
+    return *this << Slice(str);
+  }
+
+  StringBuilder &operator<<(Slice slice) {
+    if (unlikely(end_ptr_ < current_ptr_)) {
+      return on_error();
+    }
+    auto size = static_cast<size_t>(end_ptr_ + reserved_size - 1 - current_ptr_);
+    if (unlikely(slice.size() > size)) {
+      error_flag_ = true;
+    } else {
+      size = slice.size();
+    }
+    std::memcpy(current_ptr_, slice.begin(), size);
+    current_ptr_ += size;
+    return *this;
+  }
+
+  StringBuilder &operator<<(bool b) {
+    return *this << (b ? Slice("true") : Slice("false"));
+  }
+
+  StringBuilder &operator<<(char c) {
+    if (unlikely(end_ptr_ < current_ptr_)) {
+      return on_error();
+    }
+    *current_ptr_++ = c;
+    return *this;
+  }
+
+  StringBuilder &operator<<(unsigned char c) {
+    return *this << static_cast<unsigned int>(c);
+  }
+
+  StringBuilder &operator<<(signed char c) {
+    return *this << static_cast<int>(c);
+  }
+
+  StringBuilder &operator<<(int x);
+
+  StringBuilder &operator<<(unsigned int x);
+
+  StringBuilder &operator<<(long int x);
+
+  StringBuilder &operator<<(long unsigned int x);
+
+  StringBuilder &operator<<(long long int x);
+
+  StringBuilder &operator<<(long long unsigned int x);
+
+  struct FixedDouble {
+    double d;
+    int precision;
+
+    FixedDouble(double d, int precision) : d(d), precision(precision) {
+    }
+  };
+  StringBuilder &operator<<(FixedDouble x);
+
+  StringBuilder &operator<<(double x) {
+    return *this << FixedDouble(x, 6);
+  }
+
+  StringBuilder &operator<<(const void *ptr);
+
+  template <class T>
+  StringBuilder &operator<<(const T *ptr) {
+    return *this << static_cast<const void *>(ptr);
+  }
+
+ private:
+  char *begin_ptr_;
+  char *current_ptr_;
+  char *end_ptr_;
+  bool error_flag_ = false;
+  static constexpr size_t reserved_size = 30;
+
+  StringBuilder &on_error() {
+    error_flag_ = true;
+    return *this;
+  }
+};
+
+template <class T>
+std::enable_if_t<std::is_arithmetic<T>::value, string> to_string(const T &x) {
+  const size_t buf_size = 1000;
+  auto buf = StackAllocator::alloc(buf_size);
+  StringBuilder sb(buf.as_slice());
+  sb << x;
+  return sb.as_cslice().str();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Time.cpp b/libs/tdlib/td/tdutils/td/utils/Time.cpp
new file mode 100644
index 0000000000..3e62002c18
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Time.cpp
@@ -0,0 +1,19 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/Time.h"
+
+#include <cmath>
+
+namespace td {
+
+std::atomic<double> Time::now_;
+
+bool operator==(Timestamp a, Timestamp b) {
+  return std::abs(a.at() - b.at()) < 1e-6;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Time.h b/libs/tdlib/td/tdutils/td/utils/Time.h
new file mode 100644
index 0000000000..acdb8b52ef
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Time.h
@@ -0,0 +1,104 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/port/Clocks.h"
+
+#include <atomic>
+
+namespace td {
+
+class Time {
+ public:
+  static double now() {
+    double now = Clocks::monotonic();
+    now_.store(now, std::memory_order_relaxed);
+    return now;
+  }
+  static double now_cached() {
+    return now_.load(std::memory_order_relaxed);
+  }
+
+ private:
+  static std::atomic<double> now_;
+};
+
+inline void relax_timeout_at(double *timeout, double new_timeout) {
+  if (new_timeout == 0) {
+    return;
+  }
+  if (*timeout == 0 || new_timeout < *timeout) {
+    *timeout = new_timeout;
+  }
+}
+
+class Timestamp {
+ public:
+  Timestamp() = default;
+  static Timestamp never() {
+    return Timestamp{};
+  }
+  static Timestamp now() {
+    return Timestamp{Time::now()};
+  }
+  static Timestamp now_cached() {
+    return Timestamp{Time::now_cached()};
+  }
+  static Timestamp at(double timeout) {
+    return Timestamp{timeout};
+  }
+
+  static Timestamp in(double timeout) {
+    return Timestamp{Time::now_cached() + timeout};
+  }
+
+  bool is_in_past() const {
+    return at_ <= Time::now_cached();
+  }
+
+  explicit operator bool() const {
+    return at_ > 0;
+  }
+
+  double at() const {
+    return at_;
+  }
+
+  double in() const {
+    return at_ - Time::now_cached();
+  }
+
+  void relax(const Timestamp &timeout) {
+    if (!timeout) {
+      return;
+    }
+    if (!*this || at_ > timeout.at_) {
+      at_ = timeout.at_;
+    }
+  }
+
+  friend bool operator==(Timestamp a, Timestamp b);
+
+ private:
+  double at_{0};
+
+  explicit Timestamp(double timeout) : at_(timeout) {
+  }
+};
+
+template <class T>
+void parse(Timestamp &timestamp, T &parser) {
+  timestamp = Timestamp::in(parser.fetch_double() - Clocks::system());
+}
+
+template <class T>
+void store(const Timestamp &timestamp, T &storer) {
+  storer.store_binary(timestamp.at() - Time::now() + Clocks::system());
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/TimedStat.h b/libs/tdlib/td/tdutils/td/utils/TimedStat.h
new file mode 100644
index 0000000000..fc4197470d
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/TimedStat.h
@@ -0,0 +1,71 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/logging.h"
+
+#include <utility>
+
+namespace td {
+
+template <class StatT>
+class TimedStat {
+ public:
+  TimedStat(double duration, double now)
+      : duration_(duration), current_(), current_timestamp_(now), next_(), next_timestamp_(now) {
+  }
+  TimedStat() : TimedStat(0, 0) {
+  }
+  template <class EventT>
+  void add_event(const EventT &e, double now) {
+    update(now);
+    current_.on_event(e);
+    next_.on_event(e);
+  }
+  const StatT &get_stat(double now) {
+    update(now);
+    return current_;
+  }
+  std::pair<StatT, double> stat_duration(double now) {
+    update(now);
+    return std::make_pair(current_, now - current_timestamp_);
+  }
+  void clear_events() {
+    current_.clear();
+    next_.clear();
+  }
+
+ private:
+  double duration_;
+  StatT current_;
+  double current_timestamp_;
+  StatT next_;
+  double next_timestamp_;
+
+  void update(double &now) {
+    if (now < next_timestamp_) {
+      CHECK(now >= next_timestamp_ * (1 - 1e-14)) << now << " " << next_timestamp_;
+      now = next_timestamp_;
+    }
+    if (duration_ == 0) {
+      return;
+    }
+    if (next_timestamp_ + 2 * duration_ < now) {
+      current_ = StatT();
+      current_timestamp_ = now;
+      next_ = StatT();
+      next_timestamp_ = now;
+    } else if (next_timestamp_ + duration_ < now) {
+      current_ = next_;
+      current_timestamp_ = next_timestamp_;
+      next_ = StatT();
+      next_timestamp_ = now;
+    }
+  }
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Timer.cpp b/libs/tdlib/td/tdutils/td/utils/Timer.cpp
new file mode 100644
index 0000000000..dc35721caa
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Timer.cpp
@@ -0,0 +1,41 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/Timer.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+//#include  "td/utils/Slice.h"  // TODO move StringBuilder implementation to cpp, remove header
+#include "td/utils/Time.h"
+
+namespace td {
+
+Timer::Timer() : start_time_(Time::now()) {
+}
+
+StringBuilder &operator<<(StringBuilder &string_builder, const Timer &timer) {
+  return string_builder << "in " << Time::now() - timer.start_time_;
+}
+
+PerfWarningTimer::PerfWarningTimer(string name, double max_duration)
+    : name_(std::move(name)), start_at_(Time::now()), max_duration_(max_duration) {
+}
+
+PerfWarningTimer::PerfWarningTimer(PerfWarningTimer &&other)
+    : name_(std::move(other.name_)), start_at_(other.start_at_), max_duration_(other.max_duration_) {
+  other.start_at_ = 0;
+}
+
+PerfWarningTimer::~PerfWarningTimer() {
+  if (start_at_ == 0) {
+    return;
+  }
+  double duration = Time::now() - start_at_;
+  LOG_IF(WARNING, duration > max_duration_)
+      << "SLOW: " << tag("name", name_) << tag("duration", format::as_time(duration));
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Timer.h b/libs/tdlib/td/tdutils/td/utils/Timer.h
new file mode 100644
index 0000000000..65b879088d
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Timer.h
@@ -0,0 +1,38 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/StringBuilder.h"
+
+namespace td {
+
+class Timer {
+ public:
+  Timer();
+
+ private:
+  friend StringBuilder &operator<<(StringBuilder &string_builder, const Timer &timer);
+
+  double start_time_;
+};
+
+class PerfWarningTimer {
+ public:
+  explicit PerfWarningTimer(string name, double max_duration = 0.1);
+  PerfWarningTimer(const PerfWarningTimer &) = delete;
+  PerfWarningTimer &operator=(const PerfWarningTimer &) = delete;
+  PerfWarningTimer(PerfWarningTimer &&other);
+  PerfWarningTimer &operator=(PerfWarningTimer &&) = delete;
+  ~PerfWarningTimer();
+
+ private:
+  string name_;
+  double start_at_{0};
+  double max_duration_{0};
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/Variant.h b/libs/tdlib/td/tdutils/td/utils/Variant.h
new file mode 100644
index 0000000000..9b6e0561cc
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/Variant.h
@@ -0,0 +1,286 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+
+#include <new>
+#include <type_traits>
+#include <utility>
+
+namespace td {
+namespace detail {
+
+template <size_t... Args>
+class MaxSizeImpl {};
+
+template <class T>
+constexpr const T &constexpr_max(const T &a, const T &b) {
+  return a < b ? b : a;
+}
+
+template <size_t Res, size_t X, size_t... Args>
+class MaxSizeImpl<Res, X, Args...> {
+ public:
+  static constexpr size_t value = MaxSizeImpl<constexpr_max(Res, X), Args...>::value;
+};
+
+template <size_t Res>
+class MaxSizeImpl<Res> {
+ public:
+  static constexpr size_t value = Res;
+};
+
+template <class... Args>
+class MaxSize {
+ public:
+  static constexpr size_t value = MaxSizeImpl<0, sizeof(Args)...>::value;
+};
+
+template <size_t to_skip, class... Args>
+class IthTypeImpl {};
+template <class Res, class... Args>
+class IthTypeImpl<0, Res, Args...> {
+ public:
+  using type = Res;
+};
+template <size_t pos, class Skip, class... Args>
+class IthTypeImpl<pos, Skip, Args...> : public IthTypeImpl<pos - 1, Args...> {};
+
+class Dummy {};
+
+template <size_t pos, class... Args>
+class IthType : public IthTypeImpl<pos, Args..., Dummy> {};
+
+template <bool ok, int offset, class... Types>
+class FindTypeOffsetImpl {};
+
+template <int offset, class... Types>
+class FindTypeOffsetImpl<true, offset, Types...> {
+ public:
+  static constexpr int value = offset;
+};
+template <int offset, class T, class S, class... Types>
+class FindTypeOffsetImpl<false, offset, T, S, Types...>
+    : public FindTypeOffsetImpl<std::is_same<T, S>::value, offset + 1, T, Types...> {};
+template <class T, class... Types>
+class FindTypeOffset : public FindTypeOffsetImpl<false, -1, T, Types...> {};
+
+template <int offset, class... Types>
+class ForEachTypeImpl {};
+
+template <int offset>
+class ForEachTypeImpl<offset, Dummy> {
+ public:
+  template <class F>
+  static void visit(F &&f) {
+  }
+};
+
+template <int offset, class T, class... Types>
+class ForEachTypeImpl<offset, T, Types...> {
+ public:
+  template <class F>
+  static void visit(F &&f) {
+    f(offset, static_cast<T *>(nullptr));
+    ForEachTypeImpl<offset + 1, Types...>::visit(f);
+  }
+};
+
+template <class... Types>
+class ForEachType {
+ public:
+  template <class F>
+  static void visit(F &&f) {
+    ForEachTypeImpl<0, Types..., Dummy>::visit(f);
+  }
+};
+
+}  // namespace detail
+
+template <class... Types>
+class Variant {
+ public:
+  static constexpr int npos = -1;
+  Variant() {
+  }
+  Variant(Variant &&other) {
+    other.visit([&](auto &&value) { this->init_empty(std::forward<decltype(value)>(value)); });
+  }
+  Variant(const Variant &other) {
+    other.visit([&](auto &&value) { this->init_empty(std::forward<decltype(value)>(value)); });
+  }
+  Variant &operator=(Variant &&other) {
+    clear();
+    other.visit([&](auto &&value) { this->init_empty(std::forward<decltype(value)>(value)); });
+    return *this;
+  }
+  Variant &operator=(const Variant &other) {
+    clear();
+    other.visit([&](auto &&value) { this->init_empty(std::forward<decltype(value)>(value)); });
+    return *this;
+  }
+
+  bool operator==(const Variant &other) const {
+    if (offset_ != other.offset_) {
+      return false;
+    }
+    bool res = false;
+    for_each([&](int offset, auto *ptr) {
+      using T = std::decay_t<decltype(*ptr)>;
+      if (offset == offset_) {
+        res = this->get<T>() == other.template get<T>();
+      }
+    });
+    return res;
+  }
+  bool operator<(const Variant &other) const {
+    if (offset_ != other.offset_) {
+      return offset_ < other.offset_;
+    }
+    bool res = false;
+    for_each([&](int offset, auto *ptr) {
+      using T = std::decay_t<decltype(*ptr)>;
+      if (offset == offset_) {
+        res = this->get<T>() < other.template get<T>();
+      }
+    });
+    return res;
+  }
+
+  template <class T>
+  Variant(T &&t) {
+    init_empty(std::forward<T>(t));
+  }
+  template <class T>
+  Variant &operator=(T &&t) {
+    clear();
+    init_empty(std::forward<T>(t));
+    return *this;
+  }
+  template <class T>
+  static constexpr int offset() {
+    return detail::FindTypeOffset<std::decay_t<T>, Types...>::value;
+  }
+
+  template <class T>
+  void init_empty(T &&t) {
+    CHECK(offset_ == npos);
+    offset_ = offset<T>();
+    new (&get<T>()) std::decay_t<T>(std::forward<T>(t));
+  }
+  ~Variant() {
+    clear();
+  }
+
+  template <class F>
+  void visit(F &&f) {
+    for_each([&](int offset, auto *ptr) {
+      using T = std::decay_t<decltype(*ptr)>;
+      if (offset == offset_) {
+        f(std::move(*this->get_unsafe<T>()));
+      }
+    });
+  }
+  template <class F>
+  void for_each(F &&f) {
+    detail::ForEachType<Types...>::visit(f);
+  }
+  template <class F>
+  void visit(F &&f) const {
+    for_each([&](int offset, auto *ptr) {
+      using T = std::decay_t<decltype(*ptr)>;
+      if (offset == offset_) {
+        f(std::move(*this->get_unsafe<T>()));
+      }
+    });
+  }
+  template <class F>
+  void for_each(F &&f) const {
+    detail::ForEachType<Types...>::visit(f);
+  }
+
+  void clear() {
+    visit([](auto &&value) {
+      using T = std::decay_t<decltype(value)>;
+      value.~T();
+    });
+    offset_ = npos;
+  }
+
+  template <int offset>
+  auto &get() {
+    CHECK(offset == offset_);
+    return *get_unsafe<offset>();
+  }
+  template <class T>
+  auto &get() {
+    return get<offset<T>()>();
+  }
+
+  template <int offset>
+  const auto &get() const {
+    CHECK(offset == offset_);
+    return *get_unsafe<offset>();
+  }
+  template <class T>
+  const auto &get() const {
+    return get<offset<T>()>();
+  }
+
+  int32 get_offset() const {
+    return offset_;
+  }
+
+ private:
+  union {
+    int64 align_;
+    char data_[detail::MaxSize<Types...>::value];
+  };
+  int offset_{npos};
+
+  template <class T>
+  auto *get_unsafe() {
+    return reinterpret_cast<T *>(data_);
+  }
+
+  template <int offset>
+  auto *get_unsafe() {
+    using T = typename detail::IthType<offset, Types...>::type;
+    return get_unsafe<T>();
+  }
+
+  template <class T>
+  const auto *get_unsafe() const {
+    return reinterpret_cast<const T *>(data_);
+  }
+
+  template <int offset>
+  const auto *get_unsafe() const {
+    using T = typename detail::IthType<offset, Types...>::type;
+    return get_unsafe<T>();
+  }
+};
+
+template <class T, class... Types>
+auto &get(Variant<Types...> &v) {
+  return v.template get<T>();
+}
+template <class T, class... Types>
+auto &get(const Variant<Types...> &v) {
+  return v.template get<T>();
+}
+template <int T, class... Types>
+auto &get(Variant<Types...> &v) {
+  return v.template get<T>();
+}
+template <int T, class... Types>
+auto &get(const Variant<Types...> &v) {
+  return v.template get<T>();
+}
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/base64.cpp b/libs/tdlib/td/tdutils/td/utils/base64.cpp
new file mode 100644
index 0000000000..4016feaa58
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/base64.cpp
@@ -0,0 +1,261 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/base64.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <algorithm>
+#include <iterator>
+
+namespace td {
+//TODO: fix copypaste
+
+static const char *const symbols64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+string base64_encode(Slice input) {
+  string base64;
+  base64.reserve((input.size() + 2) / 3 * 4);
+  for (size_t i = 0; i < input.size();) {
+    size_t left = min(input.size() - i, static_cast<size_t>(3));
+    int c = input.ubegin()[i++] << 16;
+    base64 += symbols64[c >> 18];
+    if (left != 1) {
+      c |= input.ubegin()[i++] << 8;
+    }
+    base64 += symbols64[(c >> 12) & 63];
+    if (left == 3) {
+      c |= input.ubegin()[i++];
+    }
+    if (left != 1) {
+      base64 += symbols64[(c >> 6) & 63];
+    } else {
+      base64 += '=';
+    }
+    if (left == 3) {
+      base64 += symbols64[c & 63];
+    } else {
+      base64 += '=';
+    }
+  }
+  return base64;
+}
+
+static unsigned char char_to_value[256];
+static void init_base64_table() {
+  static bool is_inited = []() {
+    std::fill(std::begin(char_to_value), std::end(char_to_value), 64);
+    for (unsigned char i = 0; i < 64; i++) {
+      char_to_value[static_cast<size_t>(symbols64[i])] = i;
+    }
+    return true;
+  }();
+  CHECK(is_inited);
+}
+
+Result<string> base64_decode(Slice base64) {
+  init_base64_table();
+
+  if ((base64.size() & 3) != 0) {
+    return Status::Error("Wrong string length");
+  }
+
+  size_t padding_length = 0;
+  while (!base64.empty() && base64.back() == '=') {
+    base64.remove_suffix(1);
+    padding_length++;
+  }
+  if (padding_length >= 3) {
+    return Status::Error("Wrong string padding");
+  }
+
+  string output;
+  output.reserve(((base64.size() + 3) >> 2) * 3);
+  for (size_t i = 0; i < base64.size();) {
+    size_t left = min(base64.size() - i, static_cast<size_t>(4));
+    int c = 0;
+    for (size_t t = 0; t < left; t++) {
+      auto value = char_to_value[base64.ubegin()[i++]];
+      if (value == 64) {
+        return Status::Error("Wrong character in the string");
+      }
+      c |= value << ((3 - t) * 6);
+    }
+    output += static_cast<char>(static_cast<unsigned char>(c >> 16));  // implementation-defined
+    if (left == 2) {
+      if ((c & ((1 << 16) - 1)) != 0) {
+        return Status::Error("Wrong padding in the string");
+      }
+    } else {
+      output += static_cast<char>(static_cast<unsigned char>(c >> 8));  // implementation-defined
+      if (left == 3) {
+        if ((c & ((1 << 8) - 1)) != 0) {
+          return Status::Error("Wrong padding in the string");
+        }
+      } else {
+        output += static_cast<char>(static_cast<unsigned char>(c));  // implementation-defined
+      }
+    }
+  }
+  return output;
+}
+
+static const char *const url_symbols64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
+
+string base64url_encode(Slice input) {
+  string base64;
+  base64.reserve((input.size() + 2) / 3 * 4);
+  for (size_t i = 0; i < input.size();) {
+    size_t left = min(input.size() - i, static_cast<size_t>(3));
+    int c = input.ubegin()[i++] << 16;
+    base64 += url_symbols64[c >> 18];
+    if (left != 1) {
+      c |= input.ubegin()[i++] << 8;
+    }
+    base64 += url_symbols64[(c >> 12) & 63];
+    if (left == 3) {
+      c |= input.ubegin()[i++];
+    }
+    if (left != 1) {
+      base64 += url_symbols64[(c >> 6) & 63];
+    }
+    if (left == 3) {
+      base64 += url_symbols64[c & 63];
+    }
+  }
+  return base64;
+}
+
+static unsigned char url_char_to_value[256];
+static void init_base64url_table() {
+  static bool is_inited = []() {
+    std::fill(std::begin(url_char_to_value), std::end(url_char_to_value), 64);
+    for (unsigned char i = 0; i < 64; i++) {
+      url_char_to_value[static_cast<size_t>(url_symbols64[i])] = i;
+    }
+    return true;
+  }();
+  CHECK(is_inited);
+}
+
+Result<string> base64url_decode(Slice base64) {
+  init_base64url_table();
+
+  size_t padding_length = 0;
+  while (!base64.empty() && base64.back() == '=') {
+    base64.remove_suffix(1);
+    padding_length++;
+  }
+  if (padding_length >= 3 || (padding_length > 0 && ((base64.size() + padding_length) & 3) != 0)) {
+    return Status::Error("Wrong string padding");
+  }
+
+  if ((base64.size() & 3) == 1) {
+    return Status::Error("Wrong string length");
+  }
+
+  string output;
+  output.reserve(((base64.size() + 3) >> 2) * 3);
+  for (size_t i = 0; i < base64.size();) {
+    size_t left = min(base64.size() - i, static_cast<size_t>(4));
+    int c = 0;
+    for (size_t t = 0; t < left; t++) {
+      auto value = url_char_to_value[base64.ubegin()[i++]];
+      if (value == 64) {
+        return Status::Error("Wrong character in the string");
+      }
+      c |= value << ((3 - t) * 6);
+    }
+    output += static_cast<char>(static_cast<unsigned char>(c >> 16));  // implementation-defined
+    if (left == 2) {
+      if ((c & ((1 << 16) - 1)) != 0) {
+        return Status::Error("Wrong padding in the string");
+      }
+    } else {
+      output += static_cast<char>(static_cast<unsigned char>(c >> 8));  // implementation-defined
+      if (left == 3) {
+        if ((c & ((1 << 8) - 1)) != 0) {
+          return Status::Error("Wrong padding in the string");
+        }
+      } else {
+        output += static_cast<char>(static_cast<unsigned char>(c));  // implementation-defined
+      }
+    }
+  }
+  return output;
+}
+
+template <bool is_url>
+static bool is_base64_impl(Slice input) {
+  size_t padding_length = 0;
+  while (!input.empty() && input.back() == '=') {
+    input.remove_suffix(1);
+    padding_length++;
+  }
+  if (padding_length >= 3) {
+    return false;
+  }
+  if ((!is_url || padding_length > 0) && ((input.size() + padding_length) & 3) != 0) {
+    return false;
+  }
+  if (is_url && (input.size() & 3) == 1) {
+    return false;
+  }
+
+  unsigned char *table;
+  if (is_url) {
+    init_base64url_table();
+    table = url_char_to_value;
+  } else {
+    init_base64_table();
+    table = char_to_value;
+  }
+  for (auto c : input) {
+    if (table[static_cast<unsigned char>(c)] == 64) {
+      return false;
+    }
+  }
+
+  if ((input.size() & 3) == 2) {
+    auto value = table[static_cast<int>(input.back())];
+    if ((value & 15) != 0) {
+      return false;
+    }
+  }
+  if ((input.size() & 3) == 3) {
+    auto value = table[static_cast<int>(input.back())];
+    if ((value & 3) != 0) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool is_base64(Slice input) {
+  return is_base64_impl<false>(input);
+}
+
+bool is_base64url(Slice input) {
+  return is_base64_impl<true>(input);
+}
+
+string base64_filter(Slice input) {
+  string res;
+  res.reserve(input.size());
+  init_base64_table();
+  for (auto c : input) {
+    if (char_to_value[static_cast<unsigned char>(c)] != 64 || c == '=') {
+      res += c;
+    }
+  }
+  return res;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/base64.h b/libs/tdlib/td/tdutils/td/utils/base64.h
new file mode 100644
index 0000000000..cef2b4cb34
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/base64.h
@@ -0,0 +1,26 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+string base64_encode(Slice input);
+Result<string> base64_decode(Slice base64);
+
+string base64url_encode(Slice input);
+Result<string> base64url_decode(Slice base64);
+
+bool is_base64(Slice input);
+bool is_base64url(Slice input);
+
+string base64_filter(Slice input);
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/benchmark.h b/libs/tdlib/td/tdutils/td/utils/benchmark.h
new file mode 100644
index 0000000000..ddc7ad75e6
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/benchmark.h
@@ -0,0 +1,132 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/Clocks.h"
+#include "td/utils/StringBuilder.h"
+
+#include <cmath>
+#include <tuple>
+#include <utility>
+
+#define BENCH(name, desc)                          \
+  class name##Bench : public ::td::Benchmark {     \
+   public:                                         \
+    std::string get_description() const override { \
+      return (desc);                               \
+    }                                              \
+    void run(int n) override;                      \
+  };                                               \
+  void name##Bench::run(int n)
+
+namespace td {
+
+#if TD_MSVC
+
+#pragma optimize("", off)
+template <class T>
+void do_not_optimize_away(T &&datum) {
+  datum = datum;
+}
+#pragma optimize("", on)
+
+#else
+
+template <class T>
+void do_not_optimize_away(T &&datum) {
+  asm volatile("" : "+r"(datum));
+}
+
+#endif
+
+class Benchmark {
+ public:
+  Benchmark() = default;
+  Benchmark(const Benchmark &) = delete;
+  Benchmark &operator=(const Benchmark &) = delete;
+  Benchmark(Benchmark &&) = delete;
+  Benchmark &operator=(Benchmark &&) = delete;
+  virtual ~Benchmark() = default;
+
+  virtual std::string get_description() const = 0;
+
+  virtual void start_up() {
+  }
+  virtual void start_up_n(int n) {
+    start_up();
+  }
+
+  virtual void tear_down() {
+  }
+
+  virtual void run(int n) = 0;
+};
+
+inline std::pair<double, double> bench_n(Benchmark &b, int n) {
+  double total = -Clocks::monotonic();
+  b.start_up_n(n);
+  double t = -Clocks::monotonic();
+  b.run(n);
+  t += Clocks::monotonic();
+  b.tear_down();
+  total += Clocks::monotonic();
+
+  return std::make_pair(t, total);
+}
+
+inline std::pair<double, double> bench_n(Benchmark &&b, int n) {
+  return bench_n(b, n);
+}
+
+inline void bench(Benchmark &b, double max_time = 1.0) {
+  int n = 1;
+  double pass_time = 0;
+  double total_pass_time = 0;
+  while (pass_time < max_time && total_pass_time < max_time * 3 && n < (1 << 30)) {
+    n *= 2;
+    std::tie(pass_time, total_pass_time) = bench_n(b, n);
+  }
+  pass_time = n / pass_time;
+
+  int pass_cnt = 2;
+  double sum = pass_time;
+  double square_sum = pass_time * pass_time;
+  double min_pass_time = pass_time;
+  double max_pass_time = pass_time;
+
+  for (int i = 1; i < pass_cnt; i++) {
+    pass_time = n / bench_n(b, n).first;
+    sum += pass_time;
+    square_sum += pass_time * pass_time;
+    if (pass_time < min_pass_time) {
+      min_pass_time = pass_time;
+    }
+    if (pass_time > max_pass_time) {
+      max_pass_time = pass_time;
+    }
+  }
+  double average = sum / pass_cnt;
+  double d = sqrt(square_sum / pass_cnt - average * average);
+
+  auto description = b.get_description();
+  std::string pad;
+  if (description.size() < 40) {
+    pad = std::string(40 - description.size(), ' ');
+  }
+
+  LOG(ERROR) << "Bench [" << pad << description << "]: " << StringBuilder::FixedDouble(average, 3) << '['
+             << StringBuilder::FixedDouble(min_pass_time, 3) << '-' << StringBuilder::FixedDouble(max_pass_time, 3)
+             << "] ops/sec,\t" << format::as_time(1 / average) << " [d = " << StringBuilder::FixedDouble(d, 6) << ']';
+}
+
+inline void bench(Benchmark &&b, double max_time = 1.0) {
+  bench(b, max_time);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/buffer.cpp b/libs/tdlib/td/tdutils/td/utils/buffer.cpp
new file mode 100644
index 0000000000..c1a123031c
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/buffer.cpp
@@ -0,0 +1,105 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/buffer.h"
+
+#include "td/utils/port/thread_local.h"
+
+#include <new>
+
+namespace td {
+
+TD_THREAD_LOCAL BufferAllocator::BufferRawTls *BufferAllocator::buffer_raw_tls;  // static zero-initialized
+
+std::atomic<size_t> BufferAllocator::buffer_mem;
+
+size_t BufferAllocator::get_buffer_mem() {
+  return buffer_mem;
+}
+
+BufferAllocator::WriterPtr BufferAllocator::create_writer(size_t size) {
+  if (size < 512) {
+    size = 512;
+  }
+  return create_writer_exact(size);
+}
+
+BufferAllocator::WriterPtr BufferAllocator::create_writer_exact(size_t size) {
+  return WriterPtr(create_buffer_raw(size));
+}
+
+BufferAllocator::WriterPtr BufferAllocator::create_writer(size_t size, size_t prepend, size_t append) {
+  auto ptr = create_writer(size + prepend + append);
+  ptr->begin_ += prepend;
+  ptr->end_ += prepend + size;
+  return ptr;
+}
+
+BufferAllocator::ReaderPtr BufferAllocator::create_reader(size_t size) {
+  if (size < 512) {
+    return create_reader_fast(size);
+  }
+  auto ptr = create_writer_exact(size);
+  ptr->end_ += (size + 7) & -8;
+  return create_reader(ptr);
+}
+
+BufferAllocator::ReaderPtr BufferAllocator::create_reader_fast(size_t size) {
+  size = (size + 7) & -8;
+
+  init_thread_local<BufferRawTls>(buffer_raw_tls);
+
+  auto buffer_raw = buffer_raw_tls->buffer_raw.get();
+  if (buffer_raw == nullptr || buffer_raw->data_size_ - buffer_raw->end_.load(std::memory_order_relaxed) < size) {
+    buffer_raw = create_buffer_raw(4096 * 4);
+    buffer_raw_tls->buffer_raw = std::unique_ptr<BufferRaw, BufferAllocator::BufferRawDeleter>(buffer_raw);
+  }
+  buffer_raw->end_.fetch_add(size, std::memory_order_relaxed);
+  buffer_raw->ref_cnt_.fetch_add(1, std::memory_order_acq_rel);
+  return ReaderPtr(buffer_raw);
+}
+
+BufferAllocator::ReaderPtr BufferAllocator::create_reader(const WriterPtr &raw) {
+  raw->was_reader_ = true;
+  raw->ref_cnt_.fetch_add(1, std::memory_order_acq_rel);
+  return ReaderPtr(raw.get());
+}
+
+BufferAllocator::ReaderPtr BufferAllocator::create_reader(const ReaderPtr &raw) {
+  raw->ref_cnt_.fetch_add(1, std::memory_order_acq_rel);
+  return ReaderPtr(raw.get());
+}
+
+void BufferAllocator::dec_ref_cnt(BufferRaw *ptr) {
+  int left = ptr->ref_cnt_.fetch_sub(1, std::memory_order_acq_rel);
+  if (left == 1) {
+    auto buf_size = max(sizeof(BufferRaw), offsetof(BufferRaw, data_) + ptr->data_size_);
+    buffer_mem -= buf_size;
+    ptr->~BufferRaw();
+    delete[] ptr;
+  }
+}
+
+BufferRaw *BufferAllocator::create_buffer_raw(size_t size) {
+  size = (size + 7) & -8;
+
+  auto buf_size = offsetof(BufferRaw, data_) + size;
+  if (buf_size < sizeof(BufferRaw)) {
+    buf_size = sizeof(BufferRaw);
+  }
+  buffer_mem += buf_size;
+  auto *buffer_raw = reinterpret_cast<BufferRaw *>(new char[buf_size]);
+  new (buffer_raw) BufferRaw();
+  buffer_raw->data_size_ = size;
+  buffer_raw->begin_ = 0;
+  buffer_raw->end_ = 0;
+
+  buffer_raw->ref_cnt_.store(1, std::memory_order_relaxed);
+  buffer_raw->has_writer_.store(true, std::memory_order_relaxed);
+  buffer_raw->was_reader_ = false;
+  return buffer_raw;
+}
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/buffer.h b/libs/tdlib/td/tdutils/td/utils/buffer.h
new file mode 100644
index 0000000000..aa4ef8db26
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/buffer.h
@@ -0,0 +1,708 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/thread_local.h"
+#include "td/utils/Slice.h"
+
+#include <atomic>
+#include <cstring>
+#include <limits>
+
+namespace td {
+
+struct BufferRaw {
+  size_t data_size_;
+
+  // Constant after first reader is created.
+  // May be change by writer before it.
+  // So writer may do prepends till there is no reader created.
+  size_t begin_;
+
+  // Write by writer.
+  // Read by reader.
+  std::atomic<size_t> end_;
+
+  mutable std::atomic<int32> ref_cnt_;
+  std::atomic<bool> has_writer_;
+  bool was_reader_;
+
+  alignas(4) char data_[1];
+};
+
+class BufferAllocator {
+ public:
+  class DeleteWriterPtr {
+   public:
+    void operator()(BufferRaw *ptr) {
+      ptr->has_writer_.store(false, std::memory_order_release);
+      dec_ref_cnt(ptr);
+    }
+  };
+  class DeleteReaderPtr {
+   public:
+    void operator()(BufferRaw *ptr) {
+      dec_ref_cnt(ptr);
+    }
+  };
+
+  using WriterPtr = std::unique_ptr<BufferRaw, DeleteWriterPtr>;
+  using ReaderPtr = std::unique_ptr<BufferRaw, DeleteReaderPtr>;
+
+  static WriterPtr create_writer(size_t size);
+
+  static WriterPtr create_writer(size_t size, size_t prepend, size_t append);
+
+  static ReaderPtr create_reader(size_t size);
+
+  static ReaderPtr create_reader(const WriterPtr &raw);
+
+  static ReaderPtr create_reader(const ReaderPtr &raw);
+
+  static size_t get_buffer_mem();
+
+  static void clear_thread_local();
+
+ private:
+  static ReaderPtr create_reader_fast(size_t size);
+
+  static WriterPtr create_writer_exact(size_t size);
+
+  struct BufferRawDeleter {
+    void operator()(BufferRaw *ptr) {
+      dec_ref_cnt(ptr);
+    }
+  };
+  struct BufferRawTls {
+    std::unique_ptr<BufferRaw, BufferRawDeleter> buffer_raw;
+  };
+
+  static TD_THREAD_LOCAL BufferRawTls *buffer_raw_tls;
+
+  static void dec_ref_cnt(BufferRaw *ptr);
+
+  static BufferRaw *create_buffer_raw(size_t size);
+
+  static std::atomic<size_t> buffer_mem;
+};
+
+using BufferWriterPtr = BufferAllocator::WriterPtr;
+using BufferReaderPtr = BufferAllocator::ReaderPtr;
+
+class BufferSlice {
+ public:
+  BufferSlice() = default;
+  explicit BufferSlice(BufferReaderPtr buffer_ptr) : buffer_(std::move(buffer_ptr)) {
+    if (is_null()) {
+      return;
+    }
+    begin_ = buffer_->begin_;
+    sync_with_writer();
+  }
+  BufferSlice(BufferReaderPtr buffer_ptr, size_t begin, size_t end)
+      : buffer_(std::move(buffer_ptr)), begin_(begin), end_(end) {
+  }
+
+  explicit BufferSlice(size_t size) : buffer_(BufferAllocator::create_reader(size)) {
+    end_ = buffer_->end_.load(std::memory_order_relaxed);
+    begin_ = end_ - ((size + 7) & -8);
+    end_ = begin_ + size;
+  }
+
+  explicit BufferSlice(Slice slice) : BufferSlice(slice.size()) {
+    std::memcpy(as_slice().begin(), slice.begin(), slice.size());
+  }
+
+  BufferSlice(const char *ptr, size_t size) : BufferSlice(Slice(ptr, size)) {
+  }
+
+  BufferSlice clone() const {
+    if (is_null()) {
+      return BufferSlice(BufferReaderPtr(), begin_, end_);
+    }
+    return BufferSlice(BufferAllocator::create_reader(buffer_), begin_, end_);
+  }
+
+  BufferSlice copy() const {
+    if (is_null()) {
+      return BufferSlice(BufferReaderPtr(), begin_, end_);
+    }
+    return BufferSlice(as_slice());
+  }
+
+  Slice as_slice() const {
+    if (is_null()) {
+      return Slice();
+    }
+    return Slice(buffer_->data_ + begin_, size());
+  }
+
+  MutableSlice as_slice() {
+    if (is_null()) {
+      return MutableSlice();
+    }
+    return MutableSlice(buffer_->data_ + begin_, size());
+  }
+
+  Slice prepare_read() const {
+    return as_slice();
+  }
+
+  Slice after(size_t offset) const {
+    auto full = as_slice();
+    full.remove_prefix(offset);
+    return full;
+  }
+
+  bool confirm_read(size_t size) {
+    begin_ += size;
+    CHECK(begin_ <= end_);
+    return begin_ == end_;
+  }
+
+  void truncate(size_t limit) {
+    if (size() > limit) {
+      end_ = begin_ + limit;
+    }
+  }
+
+  BufferSlice from_slice(Slice slice) const {
+    auto res = BufferSlice(BufferAllocator::create_reader(buffer_));
+    res.begin_ = slice.begin() - buffer_->data_;
+    res.end_ = slice.end() - buffer_->data_;
+    CHECK(buffer_->begin_ <= res.begin_);
+    CHECK(res.begin_ <= res.end_);
+    CHECK(res.end_ <= buffer_->end_.load(std::memory_order_relaxed));
+    return res;
+  }
+
+  // like in std::string
+  char *data() {
+    return as_slice().data();
+  }
+  const char *data() const {
+    return as_slice().data();
+  }
+  char operator[](size_t at) const {
+    return as_slice()[at];
+  }
+
+  bool empty() const {
+    return size() == 0;
+  }
+
+  bool is_null() const {
+    return !buffer_;
+  }
+
+  size_t size() const {
+    return end_ - begin_;
+  }
+
+  // set end_ into writer's end_
+  size_t sync_with_writer() {
+    CHECK(!is_null());
+    auto old_end = end_;
+    end_ = buffer_->end_.load(std::memory_order_acquire);
+    return end_ - old_end;
+  }
+  bool is_writer_alive() const {
+    CHECK(!is_null());
+    return buffer_->has_writer_.load(std::memory_order_acquire);
+  }
+
+ private:
+  BufferReaderPtr buffer_;
+  size_t begin_ = 0;
+  size_t end_ = 0;
+};
+
+template <class StorerT>
+void store(const BufferSlice &buffer_slice, StorerT &storer) {
+  storer.store_string(buffer_slice);
+}
+
+template <class ParserT>
+void parse(BufferSlice &buffer_slice, ParserT &parser) {
+  buffer_slice = parser.template fetch_string<BufferSlice>();
+}
+
+class BufferWriter {
+ public:
+  BufferWriter() = default;
+  explicit BufferWriter(size_t size) : BufferWriter(BufferAllocator::create_writer(size)) {
+  }
+  BufferWriter(size_t size, size_t prepend, size_t append)
+      : BufferWriter(BufferAllocator::create_writer(size, prepend, append)) {
+  }
+  explicit BufferWriter(BufferWriterPtr buffer_ptr) : buffer_(std::move(buffer_ptr)) {
+  }
+
+  BufferSlice as_buffer_slice() const {
+    return BufferSlice(BufferAllocator::create_reader(buffer_));
+  }
+  bool is_null() const {
+    return !buffer_;
+  }
+  bool empty() const {
+    return size() == 0;
+  }
+  size_t size() const {
+    if (is_null()) {
+      return 0;
+    }
+    return buffer_->end_.load(std::memory_order_relaxed) - buffer_->begin_;
+  }
+  MutableSlice as_slice() {
+    auto end = buffer_->end_.load(std::memory_order_relaxed);
+    return MutableSlice(buffer_->data_ + buffer_->begin_, buffer_->data_ + end);
+  }
+
+  MutableSlice prepare_prepend() {
+    if (is_null()) {
+      return MutableSlice();
+    }
+    CHECK(!buffer_->was_reader_);
+    return MutableSlice(buffer_->data_, buffer_->begin_);
+  }
+  MutableSlice prepare_append() {
+    if (is_null()) {
+      return MutableSlice();
+    }
+    auto end = buffer_->end_.load(std::memory_order_relaxed);
+    return MutableSlice(buffer_->data_ + end, buffer_->data_size_ - end);
+  }
+  void confirm_append(size_t size) {
+    if (is_null()) {
+      CHECK(size == 0);
+      return;
+    }
+    auto new_end = buffer_->end_.load(std::memory_order_relaxed) + size;
+    CHECK(new_end <= buffer_->data_size_);
+    buffer_->end_.store(new_end, std::memory_order_release);
+  }
+  void confirm_prepend(size_t size) {
+    if (is_null()) {
+      CHECK(size == 0);
+      return;
+    }
+    CHECK(buffer_->begin_ >= size);
+    buffer_->begin_ -= size;
+  }
+
+ private:
+  BufferWriterPtr buffer_;
+};
+
+struct ChainBufferNode {
+  friend struct DeleteWriterPtr;
+  struct DeleteWriterPtr {
+    void operator()(ChainBufferNode *ptr) {
+      ptr->has_writer_.store(false, std::memory_order_release);
+      dec_ref_cnt(ptr);
+    }
+  };
+  friend struct DeleteReaderPtr;
+  struct DeleteReaderPtr {
+    void operator()(ChainBufferNode *ptr) {
+      dec_ref_cnt(ptr);
+    }
+  };
+  using WriterPtr = std::unique_ptr<ChainBufferNode, DeleteWriterPtr>;
+  using ReaderPtr = std::unique_ptr<ChainBufferNode, DeleteReaderPtr>;
+
+  static WriterPtr make_writer_ptr(ChainBufferNode *ptr) {
+    ptr->ref_cnt_.store(1, std::memory_order_relaxed);
+    ptr->has_writer_.store(true, std::memory_order_relaxed);
+    return WriterPtr(ptr);
+  }
+  static ReaderPtr make_reader_ptr(ChainBufferNode *ptr) {
+    ptr->ref_cnt_.fetch_add(1, std::memory_order_acq_rel);
+    return ReaderPtr(ptr);
+  }
+
+  bool has_writer() {
+    return has_writer_.load(std::memory_order_acquire);
+  }
+
+  bool unique() {
+    return ref_cnt_.load(std::memory_order_acquire) == 1;
+  }
+
+  ChainBufferNode(BufferSlice slice, bool sync_flag) : slice_(std::move(slice)), sync_flag_(sync_flag) {
+  }
+
+  // reader
+  // There are two options
+  // 1. Fixed slice of Buffer
+  // 2. Slice with non-fixed right end
+  // In each case slice_ is const. Reader should read it and use sync_with_writer on its own copy.
+  const BufferSlice slice_;
+  const bool sync_flag_{false};  // should we call slice_.sync_with_writer or not.
+
+  // writer
+  ReaderPtr next_{nullptr};
+
+ private:
+  std::atomic<int> ref_cnt_{0};
+  std::atomic<bool> has_writer_{false};
+
+  static void clear_nonrecursive(ReaderPtr ptr) {
+    while (ptr && ptr->unique()) {
+      ptr = std::move(ptr->next_);
+    }
+  }
+  static void dec_ref_cnt(ChainBufferNode *ptr) {
+    int left = --ptr->ref_cnt_;
+    if (left == 0) {
+      clear_nonrecursive(std::move(ptr->next_));
+      // TODO(refact): move memory management into allocator (?)
+      delete ptr;
+    }
+  }
+};
+
+using ChainBufferNodeWriterPtr = ChainBufferNode::WriterPtr;
+using ChainBufferNodeReaderPtr = ChainBufferNode::ReaderPtr;
+
+class ChainBufferNodeAllocator {
+ public:
+  static ChainBufferNodeWriterPtr create(BufferSlice slice, bool sync_flag) {
+    auto *ptr = new ChainBufferNode(std::move(slice), sync_flag);
+    return ChainBufferNode::make_writer_ptr(ptr);
+  }
+  static ChainBufferNodeReaderPtr clone(const ChainBufferNodeReaderPtr &ptr) {
+    if (!ptr) {
+      return ChainBufferNodeReaderPtr();
+    }
+    return ChainBufferNode::make_reader_ptr(ptr.get());
+  }
+  static ChainBufferNodeReaderPtr clone(ChainBufferNodeWriterPtr &ptr) {
+    if (!ptr) {
+      return ChainBufferNodeReaderPtr();
+    }
+    return ChainBufferNode::make_reader_ptr(ptr.get());
+  }
+};
+
+class ChainBufferIterator {
+ public:
+  ChainBufferIterator() = default;
+  explicit ChainBufferIterator(ChainBufferNodeReaderPtr head) : head_(std::move(head)) {
+    load_head();
+  }
+  ChainBufferIterator clone() const {
+    return ChainBufferIterator(ChainBufferNodeAllocator::clone(head_), reader_.clone(), need_sync_, offset_);
+  }
+
+  size_t offset() const {
+    return offset_;
+  }
+
+  void clear() {
+    *this = ChainBufferIterator();
+  }
+
+  Slice prepare_read() {
+    if (!head_) {
+      return Slice();
+    }
+    while (true) {
+      auto res = reader_.prepare_read();
+      if (!res.empty()) {
+        return res;
+      }
+      auto has_writer = head_->has_writer();
+      if (need_sync_) {
+        reader_.sync_with_writer();
+        res = reader_.prepare_read();
+        if (!res.empty()) {
+          return res;
+        }
+      }
+      if (has_writer) {
+        return Slice();
+      }
+      head_ = ChainBufferNodeAllocator::clone(head_->next_);
+      if (!head_) {
+        return Slice();
+      }
+      load_head();
+    }
+  }
+
+  // returns only head
+  BufferSlice read_as_buffer_slice(size_t limit) {
+    prepare_read();
+    auto res = reader_.clone();
+    res.truncate(limit);
+    confirm_read(res.size());
+    return res;
+  }
+
+  const BufferSlice &head() const {
+    return reader_;
+  }
+
+  void confirm_read(size_t size) {
+    offset_ += size;
+    reader_.confirm_read(size);
+  }
+
+  void advance_till_end() {
+    while (true) {
+      auto ready = prepare_read();
+      if (ready.empty()) {
+        break;
+      }
+      confirm_read(ready.size());
+    }
+  }
+
+  size_t advance(size_t offset, MutableSlice dest = MutableSlice()) {
+    size_t skipped = 0;
+    while (offset != 0) {
+      auto ready = prepare_read();
+      if (ready.empty()) {
+        break;
+      }
+
+      // read no more than offset
+      ready.truncate(offset);
+      offset -= ready.size();
+      skipped += ready.size();
+
+      // copy to dest if possible
+      auto to_dest_size = min(ready.size(), dest.size());
+      if (to_dest_size != 0) {
+        std::memcpy(dest.data(), ready.data(), to_dest_size);
+        dest.remove_prefix(to_dest_size);
+      }
+
+      confirm_read(ready.size());
+    }
+    return skipped;
+  }
+
+ private:
+  ChainBufferNodeReaderPtr head_;
+  BufferSlice reader_;      // copy of head_->slice_
+  bool need_sync_ = false;  // copy of head_->sync_flag_
+  size_t offset_ = 0;       // position in the union of all nodes
+
+  ChainBufferIterator(ChainBufferNodeReaderPtr head, BufferSlice reader, bool need_sync, size_t offset)
+      : head_(std::move(head)), reader_(std::move(reader)), need_sync_(need_sync), offset_(offset) {
+  }
+  void load_head() {
+    reader_ = head_->slice_.clone();
+    need_sync_ = head_->sync_flag_;
+  }
+};
+
+class ChainBufferReader {
+ public:
+  ChainBufferReader() = default;
+  explicit ChainBufferReader(ChainBufferNodeReaderPtr head)
+      : begin_(ChainBufferNodeAllocator::clone(head)), end_(std::move(head)) {
+    end_.advance_till_end();
+  }
+  ChainBufferReader(ChainBufferIterator begin, ChainBufferIterator end, bool sync_flag)
+      : begin_(std::move(begin)), end_(std::move(end)), sync_flag_(sync_flag) {
+  }
+  ChainBufferReader(ChainBufferNodeReaderPtr head, size_t size)
+      : begin_(ChainBufferNodeAllocator::clone(head)), end_(std::move(head)) {
+    auto advanced = end_.advance(size);
+    CHECK(advanced == size);
+  }
+  ChainBufferReader(ChainBufferReader &&) = default;
+  ChainBufferReader &operator=(ChainBufferReader &&) = default;
+  ChainBufferReader(const ChainBufferReader &) = delete;
+  ChainBufferReader &operator=(const ChainBufferReader &) = delete;
+  ~ChainBufferReader() = default;
+
+  ChainBufferReader clone() {
+    return ChainBufferReader(begin_.clone(), end_.clone(), sync_flag_);
+  }
+
+  Slice prepare_read() {
+    auto res = begin_.prepare_read();
+    res.truncate(size());
+    return res;
+  }
+
+  void confirm_read(size_t size) {
+    CHECK(size <= this->size());
+    begin_.confirm_read(size);
+  }
+
+  size_t advance(size_t offset, MutableSlice dest = MutableSlice()) {
+    CHECK(offset <= size());
+    return begin_.advance(offset, dest);
+  }
+
+  size_t size() const {
+    return end_.offset() - begin_.offset();
+  }
+  bool empty() const {
+    return size() == 0;
+  }
+
+  void sync_with_writer() {
+    if (sync_flag_) {
+      end_.advance_till_end();
+    }
+  }
+  void advance_end(size_t size) {
+    end_.advance(size);
+  }
+  const ChainBufferIterator &begin() {
+    return begin_;
+  }
+  const ChainBufferIterator &end() {
+    return end_;
+  }
+
+  // Return [begin_, tail.begin_)
+  // *this = tail
+  ChainBufferReader cut_head(ChainBufferIterator pos) {
+    auto tmp = begin_.clone();
+    begin_ = pos.clone();
+    return ChainBufferReader(std::move(tmp), std::move(pos), false);
+  }
+
+  ChainBufferReader cut_head(size_t offset) {
+    CHECK(offset <= size()) << offset << " " << size();
+    auto it = begin_.clone();
+    it.advance(offset);
+    return cut_head(std::move(it));
+  }
+
+  BufferSlice move_as_buffer_slice() {
+    BufferSlice res;
+    if (begin_.head().size() >= size()) {
+      res = begin_.read_as_buffer_slice(size());
+    } else {
+      auto save_size = size();
+      res = BufferSlice{save_size};
+      advance(save_size, res.as_slice());
+    }
+    *this = ChainBufferReader();
+    return res;
+  }
+
+  BufferSlice read_as_buffer_slice(size_t limit = std::numeric_limits<size_t>::max()) {
+    return begin_.read_as_buffer_slice(min(limit, size()));
+  }
+
+ private:
+  ChainBufferIterator begin_;  // use it for prepare_read. Fix result with size()
+  ChainBufferIterator end_;    // keep end as far as we can. use it for size()
+  bool sync_flag_ = true;      // auto sync of end_
+
+  // 1. We have fixed size. Than end_ is useless.
+  // 2. No fixed size. One has to sync end_ with end_.advance_till_end() in order to calculate size.
+};
+
+class ChainBufferWriter {
+ public:
+  ChainBufferWriter() {
+    init();
+  }
+
+  // legacy
+  static ChainBufferWriter create_empty(size_t size = 0) {
+    return ChainBufferWriter();
+  }
+
+  void init(size_t size = 0) {
+    writer_ = BufferWriter(size);
+    tail_ = ChainBufferNodeAllocator::create(writer_.as_buffer_slice(), true);
+    head_ = ChainBufferNodeAllocator::clone(tail_);
+  }
+
+  MutableSlice prepare_append(size_t hint = 0) {
+    CHECK(!empty());
+    auto res = prepare_append_inplace();
+    if (res.empty()) {
+      return prepare_append_alloc(hint);
+    }
+    return res;
+  }
+  MutableSlice prepare_append_inplace() {
+    CHECK(!empty());
+    return writer_.prepare_append();
+  }
+  MutableSlice prepare_append_alloc(size_t hint = 0) {
+    CHECK(!empty());
+    if (hint < (1 << 10)) {
+      hint = 1 << 12;
+    }
+    BufferWriter new_writer(hint);
+    auto new_tail = ChainBufferNodeAllocator::create(new_writer.as_buffer_slice(), true);
+    tail_->next_ = ChainBufferNodeAllocator::clone(new_tail);
+    writer_ = std::move(new_writer);
+    tail_ = std::move(new_tail);  // release tail_
+    return writer_.prepare_append();
+  }
+  void confirm_append(size_t size) {
+    CHECK(!empty());
+    writer_.confirm_append(size);
+  }
+
+  void append(Slice slice) {
+    while (!slice.empty()) {
+      auto ready = prepare_append(slice.size());
+      auto shift = min(ready.size(), slice.size());
+      std::memcpy(ready.data(), slice.data(), shift);
+      confirm_append(shift);
+      slice.remove_prefix(shift);
+    }
+  }
+
+  void append(BufferSlice slice) {
+    auto ready = prepare_append_inplace();
+    // TODO(perf): we have to store some stats in ChainBufferWriter
+    // for better append logic
+    if (slice.size() < (1 << 8) || ready.size() >= slice.size()) {
+      return append(slice.as_slice());
+    }
+
+    auto new_tail = ChainBufferNodeAllocator::create(std::move(slice), false);
+    tail_->next_ = ChainBufferNodeAllocator::clone(new_tail);
+    writer_ = BufferWriter();
+    tail_ = std::move(new_tail);  // release tail_
+  }
+
+  void append(ChainBufferReader &&reader) {
+    while (!reader.empty()) {
+      append(reader.read_as_buffer_slice());
+    }
+  }
+  void append(ChainBufferReader &reader) {
+    while (!reader.empty()) {
+      append(reader.read_as_buffer_slice());
+    }
+  }
+
+  ChainBufferReader extract_reader() {
+    CHECK(head_);
+    return ChainBufferReader(std::move(head_));
+  }
+
+ private:
+  bool empty() const {
+    return !tail_;
+  }
+
+  ChainBufferNodeReaderPtr head_;
+  ChainBufferNodeWriterPtr tail_;
+  BufferWriter writer_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/common.h b/libs/tdlib/td/tdutils/td/utils/common.h
new file mode 100644
index 0000000000..d1217016e3
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/common.h
@@ -0,0 +1,126 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/config.h"
+#include "td/utils/port/platform.h"
+
+// clang-format off
+#if TD_WINDOWS
+  #ifndef NTDDI_VERSION
+    #define NTDDI_VERSION 0x06020000
+  #endif
+  #ifndef WINVER
+    #define WINVER 0x0602
+  #endif
+  #ifndef _WIN32_WINNT
+    #define _WIN32_WINNT 0x0602
+  #endif
+  #ifndef NOMINMAX
+    #define NOMINMAX
+  #endif
+  #ifndef UNICODE
+    #define UNICODE
+  #endif
+  #ifndef _UNICODE
+    #define _UNICODE
+  #endif
+  #ifndef _CRT_SECURE_NO_WARNINGS
+    #define _CRT_SECURE_NO_WARNINGS
+  #endif
+
+  #include <Winsock2.h>
+  #include <ws2tcpip.h>
+
+  #include <Mswsock.h>
+  #include <Windows.h>
+  #undef ERROR
+#endif
+// clang-format on
+
+#include "td/utils/int_types.h"
+
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
+
+#define TD_DEBUG
+
+#define TD_DEFINE_STR_IMPL(x) #x
+#define TD_DEFINE_STR(x) TD_DEFINE_STR_IMPL(x)
+#define TD_CONCAT_IMPL(x, y) x##y
+#define TD_CONCAT(x, y) TD_CONCAT_IMPL(x, y)
+
+// clang-format off
+#if TD_WINDOWS
+  #define TD_DIR_SLASH '\\'
+#else
+  #define TD_DIR_SLASH '/'
+#endif
+// clang-format on
+
+namespace td {
+
+inline bool likely(bool x) {
+#if TD_CLANG || TD_GCC || TD_INTEL
+  return __builtin_expect(x, 1);
+#else
+  return x;
+#endif
+}
+
+inline bool unlikely(bool x) {
+#if TD_CLANG || TD_GCC || TD_INTEL
+  return __builtin_expect(x, 0);
+#else
+  return x;
+#endif
+}
+
+// replace std::max and std::min to not have to include <algorithm> everywhere
+// as a side bonus, accept parameters by value, so constexpr variables aren't required to be instantiated
+template <class T>
+T max(T a, T b) {
+  return a < b ? b : a;
+}
+
+template <class T>
+T min(T a, T b) {
+  return a < b ? a : b;
+}
+
+using string = std::string;
+
+template <class ValueT>
+using vector = std::vector<ValueT>;
+
+template <class ValueT>
+using unique_ptr = std::unique_ptr<ValueT>;
+
+using std::make_unique;
+
+struct Unit {};
+
+struct Auto {
+  template <class ToT>
+  operator ToT() const {
+    return ToT();
+  }
+};
+
+template <class ToT, class FromT>
+ToT &as(FromT *from) {
+  return *reinterpret_cast<ToT *>(from);
+}
+
+template <class ToT, class FromT>
+const ToT &as(const FromT *from) {
+  return *reinterpret_cast<const ToT *>(from);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/config.h b/libs/tdlib/td/tdutils/td/utils/config.h
new file mode 100644
index 0000000000..ac7462480d
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/config.h
@@ -0,0 +1,3 @@
+#pragma once
+#define TD_HAVE_OPENSSL 1
+#define TD_HAVE_ZLIB 1
diff --git a/libs/tdlib/td/tdutils/td/utils/config.h.in b/libs/tdlib/td/tdutils/td/utils/config.h.in
new file mode 100644
index 0000000000..92cbd5cdc6
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/config.h.in
@@ -0,0 +1,3 @@
+#pragma once
+#cmakedefine01 TD_HAVE_OPENSSL
+#cmakedefine01 TD_HAVE_ZLIB
diff --git a/libs/tdlib/td/tdutils/td/utils/crypto.cpp b/libs/tdlib/td/tdutils/td/utils/crypto.cpp
new file mode 100644
index 0000000000..3e54e673ab
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/crypto.cpp
@@ -0,0 +1,541 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/crypto.h"
+
+#include "td/utils/BigNum.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/RwMutex.h"
+#include "td/utils/port/thread_local.h"
+#include "td/utils/Random.h"
+
+#if TD_HAVE_OPENSSL
+#include <openssl/aes.h>
+#include <openssl/crypto.h>
+#include <openssl/evp.h>
+#include <openssl/hmac.h>
+#include <openssl/md5.h>
+#include <openssl/sha.h>
+#endif
+
+#if TD_HAVE_ZLIB
+#include <zlib.h>
+#endif
+
+#include <algorithm>
+#include <cstring>
+#include <utility>
+
+namespace td {
+
+static uint64 gcd(uint64 a, uint64 b) {
+  if (a == 0) {
+    return b;
+  }
+  if (b == 0) {
+    return a;
+  }
+
+  int shift = 0;
+  while ((a & 1) == 0 && (b & 1) == 0) {
+    a >>= 1;
+    b >>= 1;
+    shift++;
+  }
+
+  while (true) {
+    while ((a & 1) == 0) {
+      a >>= 1;
+    }
+    while ((b & 1) == 0) {
+      b >>= 1;
+    }
+    if (a > b) {
+      a -= b;
+    } else if (b > a) {
+      b -= a;
+    } else {
+      return a << shift;
+    }
+  }
+}
+
+uint64 pq_factorize(uint64 pq) {
+  if (pq < 2 || pq > (static_cast<uint64>(1) << 63)) {
+    return 1;
+  }
+  uint64 g = 0;
+  for (int i = 0, it = 0; i < 3 || it < 1000; i++) {
+    uint64 q = Random::fast(17, 32) % (pq - 1);
+    uint64 x = Random::fast_uint64() % (pq - 1) + 1;
+    uint64 y = x;
+    int lim = 1 << (min(5, i) + 18);
+    for (int j = 1; j < lim; j++) {
+      it++;
+      uint64 a = x;
+      uint64 b = x;
+      uint64 c = q;
+
+      // c += a * b
+      while (b) {
+        if (b & 1) {
+          c += a;
+          if (c >= pq) {
+            c -= pq;
+          }
+        }
+        a += a;
+        if (a >= pq) {
+          a -= pq;
+        }
+        b >>= 1;
+      }
+
+      x = c;
+      uint64 z = x < y ? pq + x - y : x - y;
+      g = gcd(z, pq);
+      if (g != 1) {
+        break;
+      }
+
+      if (!(j & (j - 1))) {
+        y = x;
+      }
+    }
+    if (g > 1 && g < pq) {
+      break;
+    }
+  }
+  if (g != 0) {
+    uint64 other = pq / g;
+    if (other < g) {
+      g = other;
+    }
+  }
+  return g;
+}
+
+#if TD_HAVE_OPENSSL
+void init_crypto() {
+  static bool is_inited = [] {
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+    return OPENSSL_init_crypto(0, nullptr) != 0;
+#else
+    OpenSSL_add_all_algorithms();
+    return true;
+#endif
+  }();
+  CHECK(is_inited);
+}
+
+template <class FromT>
+static string as_big_endian_string(const FromT &from) {
+  size_t size = sizeof(from);
+  string res(size, '\0');
+
+  auto ptr = reinterpret_cast<const unsigned char *>(&from);
+  std::memcpy(&res[0], ptr, size);
+
+  size_t i = size;
+  while (i && res[i - 1] == 0) {
+    i--;
+  }
+
+  res.resize(i);
+  std::reverse(res.begin(), res.end());
+  return res;
+}
+
+static int pq_factorize_big(Slice pq_str, string *p_str, string *q_str) {
+  // TODO: qsieve?
+  // do not work for pq == 1
+  BigNumContext context;
+  BigNum a;
+  BigNum b;
+  BigNum p;
+  BigNum q;
+  BigNum one;
+  one.set_value(1);
+
+  BigNum pq = BigNum::from_binary(pq_str);
+
+  bool found = false;
+  for (int i = 0, it = 0; !found && (i < 3 || it < 1000); i++) {
+    int32 t = Random::fast(17, 32);
+    a.set_value(Random::fast_uint32());
+    b = a;
+
+    int32 lim = 1 << (i + 23);
+    for (int j = 1; j < lim; j++) {
+      it++;
+      BigNum::mod_mul(a, a, a, pq, context);
+      a += t;
+      if (BigNum::compare(a, pq) >= 0) {
+        BigNum tmp;
+        BigNum::sub(tmp, a, pq);
+        a = std::move(tmp);
+      }
+      if (BigNum::compare(a, b) > 0) {
+        BigNum::sub(q, a, b);
+      } else {
+        BigNum::sub(q, b, a);
+      }
+      BigNum::gcd(p, q, pq, context);
+      if (BigNum::compare(p, one) != 0) {
+        found = true;
+        break;
+      }
+      if ((j & (j - 1)) == 0) {
+        b = a;
+      }
+    }
+  }
+
+  if (found) {
+    BigNum::div(&q, nullptr, pq, p, context);
+    if (BigNum::compare(p, q) > 0) {
+      std::swap(p, q);
+    }
+
+    *p_str = p.to_binary();
+    *q_str = q.to_binary();
+
+    return 0;
+  }
+
+  return -1;
+}
+
+int pq_factorize(Slice pq_str, string *p_str, string *q_str) {
+  size_t size = pq_str.size();
+  if (static_cast<int>(size) > 8 || (static_cast<int>(size) == 8 && (pq_str.begin()[0] & 128) != 0)) {
+    return pq_factorize_big(pq_str, p_str, q_str);
+  }
+
+  auto ptr = pq_str.ubegin();
+  uint64 pq = 0;
+  for (int i = 0; i < static_cast<int>(size); i++) {
+    pq = (pq << 8) | ptr[i];
+  }
+
+  uint64 p = pq_factorize(pq);
+  if (p == 0 || pq % p != 0) {
+    return -1;
+  }
+  *p_str = as_big_endian_string(p);
+  *q_str = as_big_endian_string(pq / p);
+
+  // std::string p2, q2;
+  // pq_factorize_big(pq_str, &p2, &q2);
+  // CHECK(*p_str == p2);
+  // CHECK(*q_str == q2);
+  return 0;
+}
+
+/*** AES ***/
+static void aes_ige_xcrypt(const UInt256 &aes_key, UInt256 *aes_iv, Slice from, MutableSlice to, bool encrypt_flag) {
+  AES_KEY key;
+  int err;
+  if (encrypt_flag) {
+    err = AES_set_encrypt_key(aes_key.raw, 256, &key);
+  } else {
+    err = AES_set_decrypt_key(aes_key.raw, 256, &key);
+  }
+  LOG_IF(FATAL, err != 0);
+  CHECK(from.size() <= to.size());
+  AES_ige_encrypt(from.ubegin(), to.ubegin(), from.size(), &key, aes_iv->raw, encrypt_flag);
+}
+
+void aes_ige_encrypt(const UInt256 &aes_key, UInt256 *aes_iv, Slice from, MutableSlice to) {
+  aes_ige_xcrypt(aes_key, aes_iv, from, to, true);
+}
+
+void aes_ige_decrypt(const UInt256 &aes_key, UInt256 *aes_iv, Slice from, MutableSlice to) {
+  aes_ige_xcrypt(aes_key, aes_iv, from, to, false);
+}
+
+static void aes_cbc_xcrypt(const UInt256 &aes_key, UInt128 *aes_iv, Slice from, MutableSlice to, bool encrypt_flag) {
+  AES_KEY key;
+  int err;
+  if (encrypt_flag) {
+    err = AES_set_encrypt_key(aes_key.raw, 256, &key);
+  } else {
+    err = AES_set_decrypt_key(aes_key.raw, 256, &key);
+  }
+  LOG_IF(FATAL, err != 0);
+  CHECK(from.size() <= to.size());
+  AES_cbc_encrypt(from.ubegin(), to.ubegin(), from.size(), &key, aes_iv->raw, encrypt_flag);
+}
+
+void aes_cbc_encrypt(const UInt256 &aes_key, UInt128 *aes_iv, Slice from, MutableSlice to) {
+  aes_cbc_xcrypt(aes_key, aes_iv, from, to, true);
+}
+
+void aes_cbc_decrypt(const UInt256 &aes_key, UInt128 *aes_iv, Slice from, MutableSlice to) {
+  aes_cbc_xcrypt(aes_key, aes_iv, from, to, false);
+}
+
+class AesCtrState::Impl {
+ public:
+  Impl(const UInt256 &key, const UInt128 &iv) {
+    if (AES_set_encrypt_key(key.raw, 256, &aes_key) < 0) {
+      LOG(FATAL) << "Failed to set encrypt key";
+    }
+    MutableSlice(counter, AES_BLOCK_SIZE).copy_from({iv.raw, AES_BLOCK_SIZE});
+    current_pos = 0;
+  }
+
+  void encrypt(Slice from, MutableSlice to) {
+    CHECK(to.size() >= from.size());
+    for (size_t i = 0; i < from.size(); i++) {
+      if (current_pos == 0) {
+        AES_encrypt(counter, encrypted_counter, &aes_key);
+        for (int j = 15; j >= 0; j--) {
+          if (++counter[j] != 0) {
+            break;
+          }
+        }
+      }
+      to[i] = static_cast<char>(from[i] ^ encrypted_counter[current_pos]);
+      current_pos = (current_pos + 1) & 15;
+    }
+  }
+
+ private:
+  AES_KEY aes_key;
+  uint8 counter[AES_BLOCK_SIZE];
+  uint8 encrypted_counter[AES_BLOCK_SIZE];
+  uint8 current_pos;
+};
+
+AesCtrState::AesCtrState() = default;
+AesCtrState::AesCtrState(AesCtrState &&from) = default;
+AesCtrState &AesCtrState::operator=(AesCtrState &&from) = default;
+AesCtrState::~AesCtrState() = default;
+
+void AesCtrState::init(const UInt256 &key, const UInt128 &iv) {
+  ctx_ = std::make_unique<AesCtrState::Impl>(key, iv);
+}
+
+void AesCtrState::encrypt(Slice from, MutableSlice to) {
+  ctx_->encrypt(from, to);
+}
+
+void AesCtrState::decrypt(Slice from, MutableSlice to) {
+  encrypt(from, to);  // it is the same as decrypt
+}
+
+void sha1(Slice data, unsigned char output[20]) {
+  auto result = SHA1(data.ubegin(), data.size(), output);
+  CHECK(result == output);
+}
+
+void sha256(Slice data, MutableSlice output) {
+  CHECK(output.size() >= 32);
+  auto result = SHA256(data.ubegin(), data.size(), output.ubegin());
+  CHECK(result == output.ubegin());
+}
+
+struct Sha256StateImpl {
+  SHA256_CTX ctx;
+};
+
+Sha256State::Sha256State() = default;
+Sha256State::Sha256State(Sha256State &&from) = default;
+Sha256State &Sha256State::operator=(Sha256State &&from) = default;
+Sha256State::~Sha256State() = default;
+
+void sha256_init(Sha256State *state) {
+  state->impl = std::make_unique<Sha256StateImpl>();
+  int err = SHA256_Init(&state->impl->ctx);
+  LOG_IF(FATAL, err != 1);
+}
+
+void sha256_update(Slice data, Sha256State *state) {
+  CHECK(state->impl);
+  int err = SHA256_Update(&state->impl->ctx, data.ubegin(), data.size());
+  LOG_IF(FATAL, err != 1);
+}
+
+void sha256_final(Sha256State *state, MutableSlice output) {
+  CHECK(output.size() >= 32);
+  CHECK(state->impl);
+  int err = SHA256_Final(output.ubegin(), &state->impl->ctx);
+  LOG_IF(FATAL, err != 1);
+  state->impl.reset();
+}
+
+/*** md5 ***/
+void md5(Slice input, MutableSlice output) {
+  CHECK(output.size() >= MD5_DIGEST_LENGTH);
+  auto result = MD5(input.ubegin(), input.size(), output.ubegin());
+  CHECK(result == output.ubegin());
+}
+
+void pbkdf2_sha256(Slice password, Slice salt, int iteration_count, MutableSlice dest) {
+  CHECK(dest.size() == 256 / 8) << dest.size();
+  CHECK(iteration_count > 0);
+  auto evp_md = EVP_sha256();
+  CHECK(evp_md != nullptr);
+#if OPENSSL_VERSION_NUMBER < 0x10000000L
+  HMAC_CTX ctx;
+  HMAC_CTX_init(&ctx);
+  unsigned char counter[4] = {0, 0, 0, 1};
+  int password_len = narrow_cast<int>(password.size());
+  HMAC_Init_ex(&ctx, password.data(), password_len, evp_md, nullptr);
+  HMAC_Update(&ctx, salt.ubegin(), narrow_cast<int>(salt.size()));
+  HMAC_Update(&ctx, counter, 4);
+  HMAC_Final(&ctx, dest.ubegin(), nullptr);
+  HMAC_CTX_cleanup(&ctx);
+
+  if (iteration_count > 1) {
+    unsigned char buf[32];
+    std::copy(dest.ubegin(), dest.uend(), buf);
+    for (int iter = 1; iter < iteration_count; iter++) {
+      if (HMAC(evp_md, password.data(), password_len, buf, 32, buf, nullptr) == nullptr) {
+        LOG(FATAL) << "Failed to HMAC";
+      }
+      for (int i = 0; i < 32; i++) {
+        dest[i] ^= buf[i];
+      }
+    }
+  }
+#else
+  int err = PKCS5_PBKDF2_HMAC(password.data(), narrow_cast<int>(password.size()), salt.ubegin(),
+                              narrow_cast<int>(salt.size()), iteration_count, evp_md, narrow_cast<int>(dest.size()),
+                              dest.ubegin());
+  LOG_IF(FATAL, err != 1);
+#endif
+}
+
+void hmac_sha256(Slice key, Slice message, MutableSlice dest) {
+  CHECK(dest.size() == 256 / 8);
+  unsigned int len = 0;
+  auto result = HMAC(EVP_sha256(), key.ubegin(), narrow_cast<int>(key.size()), message.ubegin(),
+                     narrow_cast<int>(message.size()), dest.ubegin(), &len);
+  CHECK(result == dest.ubegin());
+  CHECK(len == dest.size());
+}
+
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
+namespace {
+std::vector<RwMutex> &openssl_mutexes() {
+  static std::vector<RwMutex> mutexes(CRYPTO_num_locks());
+  return mutexes;
+}
+
+#if OPENSSL_VERSION_NUMBER >= 0x10000000L
+void openssl_threadid_callback(CRYPTO_THREADID *thread_id) {
+  static TD_THREAD_LOCAL int id;
+  CRYPTO_THREADID_set_pointer(thread_id, &id);
+}
+#endif
+
+void openssl_locking_function(int mode, int n, const char *file, int line) {
+  auto &mutexes = openssl_mutexes();
+  if (mode & CRYPTO_LOCK) {
+    if (mode & CRYPTO_READ) {
+      mutexes[n].lock_read_unsafe();
+    } else {
+      mutexes[n].lock_write_unsafe();
+    }
+  } else {
+    if (mode & CRYPTO_READ) {
+      mutexes[n].unlock_read_unsafe();
+    } else {
+      mutexes[n].unlock_write_unsafe();
+    }
+  }
+}
+}  // namespace
+#endif
+
+void init_openssl_threads() {
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
+  if (CRYPTO_get_locking_callback() == nullptr) {
+#if OPENSSL_VERSION_NUMBER >= 0x10000000L
+    CRYPTO_THREADID_set_callback(openssl_threadid_callback);
+#endif
+    CRYPTO_set_locking_callback(openssl_locking_function);
+  }
+#endif
+}
+#endif
+
+#if TD_HAVE_ZLIB
+uint32 crc32(Slice data) {
+  return static_cast<uint32>(::crc32(0, data.ubegin(), static_cast<uint32>(data.size())));
+}
+#endif
+
+static const uint64 crc64_table[256] = {
+    0x0000000000000000, 0xb32e4cbe03a75f6f, 0xf4843657a840a05b, 0x47aa7ae9abe7ff34, 0x7bd0c384ff8f5e33,
+    0xc8fe8f3afc28015c, 0x8f54f5d357cffe68, 0x3c7ab96d5468a107, 0xf7a18709ff1ebc66, 0x448fcbb7fcb9e309,
+    0x0325b15e575e1c3d, 0xb00bfde054f94352, 0x8c71448d0091e255, 0x3f5f08330336bd3a, 0x78f572daa8d1420e,
+    0xcbdb3e64ab761d61, 0x7d9ba13851336649, 0xceb5ed8652943926, 0x891f976ff973c612, 0x3a31dbd1fad4997d,
+    0x064b62bcaebc387a, 0xb5652e02ad1b6715, 0xf2cf54eb06fc9821, 0x41e11855055bc74e, 0x8a3a2631ae2dda2f,
+    0x39146a8fad8a8540, 0x7ebe1066066d7a74, 0xcd905cd805ca251b, 0xf1eae5b551a2841c, 0x42c4a90b5205db73,
+    0x056ed3e2f9e22447, 0xb6409f5cfa457b28, 0xfb374270a266cc92, 0x48190ecea1c193fd, 0x0fb374270a266cc9,
+    0xbc9d3899098133a6, 0x80e781f45de992a1, 0x33c9cd4a5e4ecdce, 0x7463b7a3f5a932fa, 0xc74dfb1df60e6d95,
+    0x0c96c5795d7870f4, 0xbfb889c75edf2f9b, 0xf812f32ef538d0af, 0x4b3cbf90f69f8fc0, 0x774606fda2f72ec7,
+    0xc4684a43a15071a8, 0x83c230aa0ab78e9c, 0x30ec7c140910d1f3, 0x86ace348f355aadb, 0x3582aff6f0f2f5b4,
+    0x7228d51f5b150a80, 0xc10699a158b255ef, 0xfd7c20cc0cdaf4e8, 0x4e526c720f7dab87, 0x09f8169ba49a54b3,
+    0xbad65a25a73d0bdc, 0x710d64410c4b16bd, 0xc22328ff0fec49d2, 0x85895216a40bb6e6, 0x36a71ea8a7ace989,
+    0x0adda7c5f3c4488e, 0xb9f3eb7bf06317e1, 0xfe5991925b84e8d5, 0x4d77dd2c5823b7ba, 0x64b62bcaebc387a1,
+    0xd7986774e864d8ce, 0x90321d9d438327fa, 0x231c512340247895, 0x1f66e84e144cd992, 0xac48a4f017eb86fd,
+    0xebe2de19bc0c79c9, 0x58cc92a7bfab26a6, 0x9317acc314dd3bc7, 0x2039e07d177a64a8, 0x67939a94bc9d9b9c,
+    0xd4bdd62abf3ac4f3, 0xe8c76f47eb5265f4, 0x5be923f9e8f53a9b, 0x1c4359104312c5af, 0xaf6d15ae40b59ac0,
+    0x192d8af2baf0e1e8, 0xaa03c64cb957be87, 0xeda9bca512b041b3, 0x5e87f01b11171edc, 0x62fd4976457fbfdb,
+    0xd1d305c846d8e0b4, 0x96797f21ed3f1f80, 0x2557339fee9840ef, 0xee8c0dfb45ee5d8e, 0x5da24145464902e1,
+    0x1a083bacedaefdd5, 0xa9267712ee09a2ba, 0x955cce7fba6103bd, 0x267282c1b9c65cd2, 0x61d8f8281221a3e6,
+    0xd2f6b4961186fc89, 0x9f8169ba49a54b33, 0x2caf25044a02145c, 0x6b055fede1e5eb68, 0xd82b1353e242b407,
+    0xe451aa3eb62a1500, 0x577fe680b58d4a6f, 0x10d59c691e6ab55b, 0xa3fbd0d71dcdea34, 0x6820eeb3b6bbf755,
+    0xdb0ea20db51ca83a, 0x9ca4d8e41efb570e, 0x2f8a945a1d5c0861, 0x13f02d374934a966, 0xa0de61894a93f609,
+    0xe7741b60e174093d, 0x545a57dee2d35652, 0xe21ac88218962d7a, 0x5134843c1b317215, 0x169efed5b0d68d21,
+    0xa5b0b26bb371d24e, 0x99ca0b06e7197349, 0x2ae447b8e4be2c26, 0x6d4e3d514f59d312, 0xde6071ef4cfe8c7d,
+    0x15bb4f8be788911c, 0xa6950335e42fce73, 0xe13f79dc4fc83147, 0x521135624c6f6e28, 0x6e6b8c0f1807cf2f,
+    0xdd45c0b11ba09040, 0x9aefba58b0476f74, 0x29c1f6e6b3e0301b, 0xc96c5795d7870f42, 0x7a421b2bd420502d,
+    0x3de861c27fc7af19, 0x8ec62d7c7c60f076, 0xb2bc941128085171, 0x0192d8af2baf0e1e, 0x4638a2468048f12a,
+    0xf516eef883efae45, 0x3ecdd09c2899b324, 0x8de39c222b3eec4b, 0xca49e6cb80d9137f, 0x7967aa75837e4c10,
+    0x451d1318d716ed17, 0xf6335fa6d4b1b278, 0xb199254f7f564d4c, 0x02b769f17cf11223, 0xb4f7f6ad86b4690b,
+    0x07d9ba1385133664, 0x4073c0fa2ef4c950, 0xf35d8c442d53963f, 0xcf273529793b3738, 0x7c0979977a9c6857,
+    0x3ba3037ed17b9763, 0x888d4fc0d2dcc80c, 0x435671a479aad56d, 0xf0783d1a7a0d8a02, 0xb7d247f3d1ea7536,
+    0x04fc0b4dd24d2a59, 0x3886b22086258b5e, 0x8ba8fe9e8582d431, 0xcc0284772e652b05, 0x7f2cc8c92dc2746a,
+    0x325b15e575e1c3d0, 0x8175595b76469cbf, 0xc6df23b2dda1638b, 0x75f16f0cde063ce4, 0x498bd6618a6e9de3,
+    0xfaa59adf89c9c28c, 0xbd0fe036222e3db8, 0x0e21ac88218962d7, 0xc5fa92ec8aff7fb6, 0x76d4de52895820d9,
+    0x317ea4bb22bfdfed, 0x8250e80521188082, 0xbe2a516875702185, 0x0d041dd676d77eea, 0x4aae673fdd3081de,
+    0xf9802b81de97deb1, 0x4fc0b4dd24d2a599, 0xfceef8632775faf6, 0xbb44828a8c9205c2, 0x086ace348f355aad,
+    0x34107759db5dfbaa, 0x873e3be7d8faa4c5, 0xc094410e731d5bf1, 0x73ba0db070ba049e, 0xb86133d4dbcc19ff,
+    0x0b4f7f6ad86b4690, 0x4ce50583738cb9a4, 0xffcb493d702be6cb, 0xc3b1f050244347cc, 0x709fbcee27e418a3,
+    0x3735c6078c03e797, 0x841b8ab98fa4b8f8, 0xadda7c5f3c4488e3, 0x1ef430e13fe3d78c, 0x595e4a08940428b8,
+    0xea7006b697a377d7, 0xd60abfdbc3cbd6d0, 0x6524f365c06c89bf, 0x228e898c6b8b768b, 0x91a0c532682c29e4,
+    0x5a7bfb56c35a3485, 0xe955b7e8c0fd6bea, 0xaeffcd016b1a94de, 0x1dd181bf68bdcbb1, 0x21ab38d23cd56ab6,
+    0x9285746c3f7235d9, 0xd52f0e859495caed, 0x6601423b97329582, 0xd041dd676d77eeaa, 0x636f91d96ed0b1c5,
+    0x24c5eb30c5374ef1, 0x97eba78ec690119e, 0xab911ee392f8b099, 0x18bf525d915feff6, 0x5f1528b43ab810c2,
+    0xec3b640a391f4fad, 0x27e05a6e926952cc, 0x94ce16d091ce0da3, 0xd3646c393a29f297, 0x604a2087398eadf8,
+    0x5c3099ea6de60cff, 0xef1ed5546e415390, 0xa8b4afbdc5a6aca4, 0x1b9ae303c601f3cb, 0x56ed3e2f9e224471,
+    0xe5c372919d851b1e, 0xa26908783662e42a, 0x114744c635c5bb45, 0x2d3dfdab61ad1a42, 0x9e13b115620a452d,
+    0xd9b9cbfcc9edba19, 0x6a978742ca4ae576, 0xa14cb926613cf817, 0x1262f598629ba778, 0x55c88f71c97c584c,
+    0xe6e6c3cfcadb0723, 0xda9c7aa29eb3a624, 0x69b2361c9d14f94b, 0x2e184cf536f3067f, 0x9d36004b35545910,
+    0x2b769f17cf112238, 0x9858d3a9ccb67d57, 0xdff2a94067518263, 0x6cdce5fe64f6dd0c, 0x50a65c93309e7c0b,
+    0xe388102d33392364, 0xa4226ac498dedc50, 0x170c267a9b79833f, 0xdcd7181e300f9e5e, 0x6ff954a033a8c131,
+    0x28532e49984f3e05, 0x9b7d62f79be8616a, 0xa707db9acf80c06d, 0x14299724cc279f02, 0x5383edcd67c06036,
+    0xe0ada17364673f59};
+
+static uint64 crc64_partial(Slice data, uint64 crc) {
+  const char *p = data.begin();
+  for (auto len = data.size(); len > 0; len--) {
+    crc = crc64_table[(crc ^ *p++) & 0xff] ^ (crc >> 8);
+  }
+  return crc;
+}
+
+uint64 crc64(Slice data) {
+  return crc64_partial(data, static_cast<uint64>(-1)) ^ static_cast<uint64>(-1);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/crypto.h b/libs/tdlib/td/tdutils/td/utils/crypto.h
new file mode 100644
index 0000000000..23ac694bfb
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/crypto.h
@@ -0,0 +1,79 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+
+namespace td {
+
+uint64 pq_factorize(uint64 pq);
+
+#if TD_HAVE_OPENSSL
+void init_crypto();
+
+int pq_factorize(Slice pq_str, string *p_str, string *q_str);
+
+void aes_ige_encrypt(const UInt256 &aes_key, UInt256 *aes_iv, Slice from, MutableSlice to);
+void aes_ige_decrypt(const UInt256 &aes_key, UInt256 *aes_iv, Slice from, MutableSlice to);
+
+void aes_cbc_encrypt(const UInt256 &aes_key, UInt128 *aes_iv, Slice from, MutableSlice to);
+void aes_cbc_decrypt(const UInt256 &aes_key, UInt128 *aes_iv, Slice from, MutableSlice to);
+
+class AesCtrState {
+ public:
+  AesCtrState();
+  AesCtrState(const AesCtrState &from) = delete;
+  AesCtrState &operator=(const AesCtrState &from) = delete;
+  AesCtrState(AesCtrState &&from);
+  AesCtrState &operator=(AesCtrState &&from);
+  ~AesCtrState();
+
+  void init(const UInt256 &key, const UInt128 &iv);
+
+  void encrypt(Slice from, MutableSlice to);
+
+  void decrypt(Slice from, MutableSlice to);
+
+ private:
+  class Impl;
+  std::unique_ptr<Impl> ctx_;
+};
+
+void sha1(Slice data, unsigned char output[20]);
+
+void sha256(Slice data, MutableSlice output);
+
+struct Sha256StateImpl;
+
+struct Sha256State {
+  Sha256State();
+  Sha256State(Sha256State &&from);
+  Sha256State &operator=(Sha256State &&from);
+  ~Sha256State();
+  std::unique_ptr<Sha256StateImpl> impl;
+};
+
+void sha256_init(Sha256State *state);
+void sha256_update(Slice data, Sha256State *state);
+void sha256_final(Sha256State *state, MutableSlice output);
+
+void md5(Slice input, MutableSlice output);
+
+void pbkdf2_sha256(Slice password, Slice salt, int iteration_count, MutableSlice dest);
+void hmac_sha256(Slice key, Slice message, MutableSlice dest);
+
+void init_openssl_threads();
+#endif
+
+#if TD_HAVE_ZLIB
+uint32 crc32(Slice data);
+#endif
+
+uint64 crc64(Slice data);
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/filesystem.cpp b/libs/tdlib/td/tdutils/td/utils/filesystem.cpp
new file mode 100644
index 0000000000..b22418151c
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/filesystem.cpp
@@ -0,0 +1,123 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/filesystem.h"
+
+#include "td/utils/buffer.h"
+#include "td/utils/logging.h"
+#include "td/utils/PathView.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/unicode.h"
+#include "td/utils/utf8.h"
+
+namespace td {
+
+Result<BufferSlice> read_file(CSlice path, int64 size) {
+  TRY_RESULT(from_file, FileFd::open(path, FileFd::Read));
+  if (size == -1) {
+    size = from_file.get_size();
+  }
+  BufferWriter content{static_cast<size_t>(size), 0, 0};
+  TRY_RESULT(got_size, from_file.read(content.as_slice()));
+  if (got_size != static_cast<size_t>(size)) {
+    return Status::Error("Failed to read file");
+  }
+  from_file.close();
+  return content.as_buffer_slice();
+}
+
+// Very straightforward function. Don't expect much of it.
+Status copy_file(CSlice from, CSlice to, int64 size) {
+  TRY_RESULT(content, read_file(from, size));
+  return write_file(to, content.as_slice());
+}
+
+Status write_file(CSlice to, Slice data) {
+  auto size = data.size();
+  TRY_RESULT(to_file, FileFd::open(to, FileFd::Truncate | FileFd::Create | FileFd::Write));
+  TRY_RESULT(written, to_file.write(data));
+  if (written != static_cast<size_t>(size)) {
+    return Status::Error(PSLICE() << "Failed to write file: written " << written << " bytes instead of " << size);
+  }
+  to_file.close();
+  return Status::OK();
+}
+
+static std::string clean_filename_part(Slice name, int max_length) {
+  auto is_ok = [](uint32 code) {
+    if (code < 32) {
+      return false;
+    }
+    if (code < 127) {
+      switch (code) {
+        case '<':
+        case '>':
+        case ':':
+        case '"':
+        case '/':
+        case '\\':
+        case '|':
+        case '?':
+        case '*':
+        case '&':
+        case '`':
+        case '\'':
+          return false;
+        default:
+          return true;
+      }
+    }
+    auto category = get_unicode_simple_category(code);
+
+    return category == UnicodeSimpleCategory::Letter || category == UnicodeSimpleCategory::DecimalNumber ||
+           category == UnicodeSimpleCategory::Number;
+  };
+
+  std::string new_name;
+  int size = 0;
+  for (auto *it = name.ubegin(); it != name.uend() && size < max_length;) {
+    uint32 code;
+    it = next_utf8_unsafe(it, &code);
+    if (!is_ok(code)) {
+      code = ' ';
+    }
+    if (new_name.empty() && (code == ' ' || code == '.')) {
+      continue;
+    }
+    append_utf8_character(new_name, code);
+    size++;
+  }
+
+  while (!new_name.empty() && (new_name.back() == ' ' || new_name.back() == '.')) {
+    new_name.pop_back();
+  }
+  return new_name;
+}
+
+std::string clean_filename(CSlice name) {
+  if (!check_utf8(name)) {
+    return {};
+  }
+
+  PathView path_view(name);
+  auto filename = clean_filename_part(path_view.file_stem(), 60);
+  auto extension = clean_filename_part(path_view.extension(), 20);
+  if (!extension.empty()) {
+    if (filename.empty()) {
+      filename = std::move(extension);
+    } else {
+      filename.reserve(filename.size() + 1 + extension.size());
+      filename += '.';
+      filename += extension;
+    }
+  }
+
+  return filename;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/filesystem.h b/libs/tdlib/td/tdutils/td/utils/filesystem.h
new file mode 100644
index 0000000000..4bb1b17191
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/filesystem.h
@@ -0,0 +1,22 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/buffer.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+Result<BufferSlice> read_file(CSlice path, int64 size = -1);
+
+Status copy_file(CSlice from, CSlice to, int64 size = -1);
+
+Status write_file(CSlice to, Slice data);
+
+std::string clean_filename(CSlice name);
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/find_boundary.cpp b/libs/tdlib/td/tdutils/td/utils/find_boundary.cpp
new file mode 100644
index 0000000000..44fc264ab5
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/find_boundary.cpp
@@ -0,0 +1,53 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/find_boundary.h"
+
+#include "td/utils/logging.h"
+
+#include <cstring>
+
+namespace td {
+
+bool find_boundary(ChainBufferReader range, Slice boundary, size_t &already_read) {
+  range.advance(already_read);
+
+  const int MAX_BOUNDARY_LENGTH = 70;
+  CHECK(boundary.size() <= MAX_BOUNDARY_LENGTH + 4);
+  while (!range.empty()) {
+    Slice ready = range.prepare_read();
+    if (ready[0] == boundary[0]) {
+      if (range.size() < boundary.size()) {
+        return false;
+      }
+      auto save_range = range.clone();
+      char x[MAX_BOUNDARY_LENGTH + 4];
+      range.advance(boundary.size(), {x, sizeof(x)});
+      if (std::memcmp(x, boundary.data(), boundary.size()) == 0) {
+        return true;
+      }
+
+      // not a boundary, restoring previous state and skip one symbol
+      range = std::move(save_range);
+      range.advance(1);
+      already_read++;
+    } else {
+      const char *ptr = static_cast<const char *>(std::memchr(ready.data(), boundary[0], ready.size()));
+      size_t shift;
+      if (ptr == nullptr) {
+        shift = ready.size();
+      } else {
+        shift = ptr - ready.data();
+      }
+      already_read += shift;
+      range.advance(shift);
+    }
+  }
+
+  return false;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/find_boundary.h b/libs/tdlib/td/tdutils/td/utils/find_boundary.h
new file mode 100644
index 0000000000..5b424cf23c
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/find_boundary.h
@@ -0,0 +1,17 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+
+namespace td {
+
+bool find_boundary(ChainBufferReader range, Slice boundary, size_t &already_read);
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/format.h b/libs/tdlib/td/tdutils/td/utils/format.h
new file mode 100644
index 0000000000..745ad0d8a5
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/format.h
@@ -0,0 +1,312 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/invoke.h"  // for tuple_for_each
+#include "td/utils/Slice.h"
+#include "td/utils/StringBuilder.h"
+
+#include <tuple>
+#include <utility>
+
+namespace td {
+namespace format {
+/*** HexDump ***/
+template <std::size_t size, bool reversed = true>
+struct HexDumpSize {
+  const unsigned char *data;
+};
+
+inline char hex_digit(int x) {
+  return "0123456789abcdef"[x];
+}
+
+template <std::size_t size, bool reversed>
+StringBuilder &operator<<(StringBuilder &builder, const HexDumpSize<size, reversed> &dump) {
+  const unsigned char *ptr = dump.data;
+  // TODO: append unsafe
+  for (std::size_t i = 0; i < size; i++) {
+    int xy = ptr[reversed ? size - 1 - i : i];
+    int x = xy >> 4;
+    int y = xy & 15;
+    builder << hex_digit(x) << hex_digit(y);
+  }
+  return builder;
+}
+
+template <std::size_t align>
+struct HexDumpSlice {
+  Slice slice;
+};
+
+template <std::size_t align>
+StringBuilder &operator<<(StringBuilder &builder, const HexDumpSlice<align> &dump) {
+  std::size_t size = dump.slice.size();
+  const unsigned char *ptr = dump.slice.ubegin();
+
+  builder << '\n';
+
+  const std::size_t part = size % align;
+  if (part) {
+    builder << HexDumpSlice<1>{Slice(ptr, part)} << '\n';
+  }
+  size -= part;
+  ptr += part;
+
+  for (std::size_t i = 0; i < size; i += align) {
+    builder << HexDumpSize<align>{ptr};
+    ptr += align;
+
+    if (((i / align) & 15) == 15 || i + align >= size) {
+      builder << '\n';
+    } else {
+      builder << ' ';
+    }
+  }
+
+  return builder;
+}
+
+inline StringBuilder &operator<<(StringBuilder &builder, const HexDumpSlice<0> &dump) {
+  auto size = dump.slice.size();
+  const uint8 *ptr = dump.slice.ubegin();
+  for (size_t i = 0; i < size; i++) {
+    builder << HexDumpSize<1>{ptr + i};
+  }
+  return builder;
+}
+
+template <std::size_t align>
+HexDumpSlice<align> as_hex_dump(Slice slice) {
+  return HexDumpSlice<align>{slice};
+}
+
+template <std::size_t align>
+HexDumpSlice<align> as_hex_dump(MutableSlice slice) {
+  return HexDumpSlice<align>{slice};
+}
+
+template <std::size_t align, class T>
+HexDumpSlice<align> as_hex_dump(const T &value) {
+  return HexDumpSlice<align>{Slice(&value, sizeof(value))};
+}
+template <class T>
+HexDumpSize<sizeof(T), true> as_hex_dump(const T &value) {
+  return HexDumpSize<sizeof(T), true>{reinterpret_cast<const unsigned char *>(&value)};
+}
+
+/*** Hex ***/
+template <class T>
+struct Hex {
+  const T &value;
+};
+
+template <class T>
+Hex<T> as_hex(const T &value) {
+  return Hex<T>{value};
+}
+
+template <class T>
+StringBuilder &operator<<(StringBuilder &builder, const Hex<T> &hex) {
+  builder << "0x" << as_hex_dump(hex.value);
+  return builder;
+}
+
+/*** Binary ***/
+template <class T>
+struct Binary {
+  const T &value;
+};
+
+template <class T>
+Binary<T> as_binary(const T &value) {
+  return Binary<T>{value};
+}
+
+template <class T>
+StringBuilder &operator<<(StringBuilder &builder, const Binary<T> &hex) {
+  for (size_t i = 0; i < sizeof(T) * 8; i++) {
+    builder << ((hex.value >> i) & 1 ? '1' : '0');
+  }
+  return builder;
+}
+
+/*** Escaped ***/
+struct Escaped {
+  Slice str;
+};
+
+inline StringBuilder &operator<<(StringBuilder &builder, const Escaped &escaped) {
+  Slice str = escaped.str;
+  for (unsigned char c : str) {
+    if (c > 31 && c < 127 && c != '"' && c != '\\') {
+      builder << static_cast<char>(c);
+    } else {
+      const char *oct = "01234567";
+      builder << "\\0" << oct[c >> 6] << oct[(c >> 3) & 7] << oct[c & 7];
+    }
+  }
+  return builder;
+}
+
+inline Escaped escaped(Slice slice) {
+  return Escaped{slice};
+}
+
+/*** Time to string ***/
+struct Time {
+  double seconds_;
+};
+
+inline StringBuilder &operator<<(StringBuilder &logger, Time t) {
+  struct NamedValue {
+    const char *name;
+    double value;
+  };
+
+  static constexpr NamedValue durations[] = {{"ns", 1e-9}, {"us", 1e-6}, {"ms", 1e-3}, {"s", 1}};
+  static constexpr size_t durations_n = sizeof(durations) / sizeof(NamedValue);
+
+  size_t i = 0;
+  while (i + 1 < durations_n && t.seconds_ > 10 * durations[i + 1].value) {
+    i++;
+  }
+  logger << StringBuilder::FixedDouble(t.seconds_ / durations[i].value, 1) << durations[i].name;
+  return logger;
+}
+
+inline Time as_time(double seconds) {
+  return Time{seconds};
+}
+
+/*** Size to string ***/
+struct Size {
+  uint64 size_;
+};
+
+inline StringBuilder &operator<<(StringBuilder &logger, Size t) {
+  struct NamedValue {
+    const char *name;
+    uint64 value;
+  };
+
+  static constexpr NamedValue sizes[] = {{"B", 1}, {"KB", 1 << 10}, {"MB", 1 << 20}, {"GB", 1 << 30}};
+  static constexpr size_t sizes_n = sizeof(sizes) / sizeof(NamedValue);
+
+  size_t i = 0;
+  while (i + 1 < sizes_n && t.size_ > 10 * sizes[i + 1].value) {
+    i++;
+  }
+  logger << t.size_ / sizes[i].value << sizes[i].name;
+  return logger;
+}
+
+inline Size as_size(uint64 size) {
+  return Size{size};
+}
+
+/*** Array to string ***/
+template <class ArrayT>
+struct Array {
+  const ArrayT &ref;
+};
+
+template <class ArrayT>
+StringBuilder &operator<<(StringBuilder &stream, const Array<ArrayT> &array) {
+  bool first = true;
+  stream << Slice("{");
+  for (auto &x : array.ref) {
+    if (!first) {
+      stream << Slice(", ");
+    }
+    stream << x;
+    first = false;
+  }
+  return stream << Slice("}");
+}
+
+template <class ArrayT>
+Array<ArrayT> as_array(const ArrayT &array) {
+  return Array<ArrayT>{array};
+}
+
+/*** Tagged ***/
+template <class ValueT>
+struct Tagged {
+  Slice tag;
+  const ValueT &ref;
+};
+
+template <class ValueT>
+StringBuilder &operator<<(StringBuilder &stream, const Tagged<ValueT> &tagged) {
+  return stream << "[" << tagged.tag << ":" << tagged.ref << "]";
+}
+
+template <class ValueT>
+Tagged<ValueT> tag(Slice tag, const ValueT &ref) {
+  return Tagged<ValueT>{tag, ref};
+}
+
+/*** Cond ***/
+inline StringBuilder &operator<<(StringBuilder &sb, Unit) {
+  return sb;
+}
+
+template <class TrueT, class FalseT>
+struct Cond {
+  bool flag;
+  const TrueT &on_true;
+  const FalseT &on_false;
+};
+
+template <class TrueT, class FalseT>
+StringBuilder &operator<<(StringBuilder &sb, const Cond<TrueT, FalseT> &cond) {
+  if (cond.flag) {
+    return sb << cond.on_true;
+  } else {
+    return sb << cond.on_false;
+  }
+}
+
+template <class TrueT, class FalseT = Unit>
+Cond<TrueT, FalseT> cond(bool flag, const TrueT &on_true, const FalseT &on_false = FalseT()) {
+  return Cond<TrueT, FalseT>{flag, on_true, on_false};
+}
+
+/*** Concat ***/
+template <class T>
+struct Concat {
+  T args;
+};
+
+template <class T>
+StringBuilder &operator<<(StringBuilder &sb, const Concat<T> &concat) {
+  tuple_for_each(concat.args, [&sb](auto &x) { sb << x; });
+  return sb;
+}
+
+template <class... ArgsT>
+auto concat(const ArgsT &... args) {
+  return Concat<decltype(std::tie(args...))>{std::tie(args...)};
+}
+
+}  // namespace format
+
+using format::tag;
+
+template <class A, class B>
+StringBuilder &operator<<(StringBuilder &sb, const std::pair<A, B> &p) {
+  return sb << "[" << p.first << ";" << p.second << "]";
+}
+
+template <class T>
+StringBuilder &operator<<(StringBuilder &stream, const vector<T> &vec) {
+  return stream << format::as_array(vec);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/int_types.h b/libs/tdlib/td/tdutils/td/utils/int_types.h
new file mode 100644
index 0000000000..08ff1099c2
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/int_types.h
@@ -0,0 +1,65 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/platform.h"
+
+#include <cstddef>
+#include <cstdint>
+#include <cstring>
+
+namespace td {
+
+#if !TD_WINDOWS
+using size_t = std::size_t;
+#endif
+
+using int8 = std::int8_t;
+using int16 = std::int16_t;
+using uint16 = std::uint16_t;
+using int32 = std::int32_t;
+using uint32 = std::uint32_t;
+using int64 = std::int64_t;
+using uint64 = std::uint64_t;
+
+static_assert(sizeof(std::uint8_t) == sizeof(unsigned char), "Unsigned char expected to be 8-bit");
+using uint8 = unsigned char;
+
+#if TD_MSVC
+#pragma warning(push)
+#pragma warning(disable : 4309)
+#endif
+
+static_assert(static_cast<char>(128) == -128 || static_cast<char>(128) == 128,
+              "Unexpected cast to char implementation-defined behaviour");
+static_assert(static_cast<char>(256) == 0, "Unexpected cast to char implementation-defined behaviour");
+static_assert(static_cast<char>(-256) == 0, "Unexpected cast to char implementation-defined behaviour");
+
+#if TD_MSVC
+#pragma warning(pop)
+#endif
+
+template <size_t size>
+struct UInt {
+  static_assert(size % 8 == 0, "size should be divisible by 8");
+  uint8 raw[size / 8];
+};
+
+template <size_t size>
+inline bool operator==(const UInt<size> &a, const UInt<size> &b) {
+  return std::memcmp(a.raw, b.raw, sizeof(a.raw)) == 0;
+}
+
+template <size_t size>
+inline bool operator!=(const UInt<size> &a, const UInt<size> &b) {
+  return !(a == b);
+}
+
+using UInt128 = UInt<128>;
+using UInt256 = UInt<256>;
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/invoke.h b/libs/tdlib/td/tdutils/td/utils/invoke.h
new file mode 100644
index 0000000000..e9e56fc2c5
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/invoke.h
@@ -0,0 +1,178 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+#include <functional>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+
+namespace td {
+
+namespace detail {
+
+template <std::size_t... S>
+struct IntSeq {};
+
+template <std::size_t L, std::size_t N, std::size_t... S>
+struct IntSeqGen : IntSeqGen<L, N - 1, L + N - 1, S...> {};
+
+template <std::size_t L, std::size_t... S>
+struct IntSeqGen<L, 0, S...> {
+  using type = IntSeq<S...>;
+};
+
+template <bool... Args>
+class LogicAndImpl {};
+
+template <bool Res, bool X, bool... Args>
+class LogicAndImpl<Res, X, Args...> {
+ public:
+  static constexpr bool value = LogicAndImpl<(Res && X), Args...>::value;
+};
+
+template <bool Res>
+class LogicAndImpl<Res> {
+ public:
+  static constexpr bool value = Res;
+};
+
+template <std::size_t N>
+using IntRange = typename IntSeqGen<0, N>::type;
+
+template <class T>
+struct is_reference_wrapper : std::false_type {};
+
+template <class U>
+struct is_reference_wrapper<std::reference_wrapper<U>> : std::true_type {};
+
+template <class Base, class T, class Derived, class... Args>
+auto invoke_impl(T Base::*pmf, Derived &&ref,
+                 Args &&... args) noexcept(noexcept((std::forward<Derived>(ref).*pmf)(std::forward<Args>(args)...)))
+    -> std::enable_if_t<std::is_function<T>::value && std::is_base_of<Base, std::decay<Derived>>::value,
+                        decltype((std::forward<Derived>(ref).*pmf)(std::forward<Args>(args)...))> {
+  return (std::forward<Derived>(ref).*pmf)(std::forward<Args>(args)...);
+}
+
+template <class Base, class T, class RefWrap, class... Args>
+auto invoke_impl(T Base::*pmf, RefWrap &&ref,
+                 Args &&... args) noexcept(noexcept((ref.get().*pmf)(std::forward<Args>(args)...)))
+    -> std::enable_if_t<std::is_function<T>::value && is_reference_wrapper<std::decay_t<RefWrap>>::value,
+                        decltype((ref.get().*pmf)(std::forward<Args>(args)...))>
+
+{
+  return (ref.get().*pmf)(std::forward<Args>(args)...);
+}
+
+template <class Base, class T, class Pointer, class... Args>
+auto invoke_impl(T Base::*pmf, Pointer &&ptr,
+                 Args &&... args) noexcept(noexcept(((*std::forward<Pointer>(ptr)).*pmf)(std::forward<Args>(args)...)))
+    -> std::enable_if_t<std::is_function<T>::value && !is_reference_wrapper<std::decay_t<Pointer>>::value &&
+                            !std::is_base_of<Base, std::decay_t<Pointer>>::value,
+                        decltype(((*std::forward<Pointer>(ptr)).*pmf)(std::forward<Args>(args)...))> {
+  return ((*std::forward<Pointer>(ptr)).*pmf)(std::forward<Args>(args)...);
+}
+
+template <class Base, class T, class Derived>
+auto invoke_impl(T Base::*pmd, Derived &&ref) noexcept(noexcept(std::forward<Derived>(ref).*pmd))
+    -> std::enable_if_t<!std::is_function<T>::value && std::is_base_of<Base, std::decay_t<Derived>>::value,
+                        decltype(std::forward<Derived>(ref).*pmd)> {
+  return std::forward<Derived>(ref).*pmd;
+}
+
+template <class Base, class T, class RefWrap>
+auto invoke_impl(T Base::*pmd, RefWrap &&ref) noexcept(noexcept(ref.get().*pmd))
+    -> std::enable_if_t<!std::is_function<T>::value && is_reference_wrapper<std::decay_t<RefWrap>>::value,
+                        decltype(ref.get().*pmd)> {
+  return ref.get().*pmd;
+}
+
+template <class Base, class T, class Pointer>
+auto invoke_impl(T Base::*pmd, Pointer &&ptr) noexcept(noexcept((*std::forward<Pointer>(ptr)).*pmd))
+    -> std::enable_if_t<!std::is_function<T>::value && !is_reference_wrapper<std::decay_t<Pointer>>::value &&
+                            !std::is_base_of<Base, std::decay_t<Pointer>>::value,
+                        decltype((*std::forward<Pointer>(ptr)).*pmd)> {
+  return (*std::forward<Pointer>(ptr)).*pmd;
+}
+
+template <class F, class... Args>
+auto invoke_impl(F &&f, Args &&... args) noexcept(noexcept(std::forward<F>(f)(std::forward<Args>(args)...)))
+    -> std::enable_if_t<!std::is_member_pointer<std::decay_t<F>>::value,
+                        decltype(std::forward<F>(f)(std::forward<Args>(args)...))> {
+  return std::forward<F>(f)(std::forward<Args>(args)...);
+}
+
+template <class F, class... ArgTypes>
+auto invoke(F &&f,
+            ArgTypes &&... args) noexcept(noexcept(invoke_impl(std::forward<F>(f), std::forward<ArgTypes>(args)...)))
+    -> decltype(invoke_impl(std::forward<F>(f), std::forward<ArgTypes>(args)...)) {
+  return invoke_impl(std::forward<F>(f), std::forward<ArgTypes>(args)...);
+}
+
+template <class F, class... Args, std::size_t... S>
+void call_tuple_impl(F &func, std::tuple<Args...> &&tuple, IntSeq<S...>) {
+  func(std::forward<Args>(std::get<S>(tuple))...);
+}
+
+template <class... Args, std::size_t... S>
+void invoke_tuple_impl(std::tuple<Args...> &&tuple, IntSeq<S...>) {
+  invoke(std::forward<Args>(std::get<S>(tuple))...);
+}
+
+template <class Actor, class F, class... Args, std::size_t... S>
+void mem_call_tuple_impl(Actor *actor, F &func, std::tuple<Args...> &&tuple, IntSeq<S...>) {
+  (actor->*func)(std::forward<Args>(std::get<S>(tuple))...);
+}
+
+template <class F, class... Args, std::size_t... S>
+void tuple_for_each_impl(std::tuple<Args...> &tuple, const F &func, IntSeq<S...>) {
+  const auto &dummy = {0, (func(std::get<S>(tuple)), 0)...};
+  (void)dummy;
+}
+
+template <class F, class... Args, std::size_t... S>
+void tuple_for_each_impl(const std::tuple<Args...> &tuple, const F &func, IntSeq<S...>) {
+  const auto &dummy = {0, (func(std::get<S>(tuple)), 0)...};
+  (void)dummy;
+}
+
+}  // namespace detail
+
+template <bool... Args>
+class LogicAnd {
+ public:
+  static constexpr bool value = detail::LogicAndImpl<true, Args...>::value;
+};
+
+template <class F, class... Args>
+void call_tuple(F &func, std::tuple<Args...> &&tuple) {
+  detail::call_tuple_impl(func, std::move(tuple), detail::IntRange<sizeof...(Args)>());
+}
+
+template <class... Args>
+void invoke_tuple(std::tuple<Args...> &&tuple) {
+  detail::invoke_tuple_impl(std::move(tuple), detail::IntRange<sizeof...(Args)>());
+}
+
+template <class Actor, class F, class... Args>
+void mem_call_tuple(Actor *actor, F &func, std::tuple<Args...> &&tuple) {
+  detail::mem_call_tuple_impl(actor, func, std::move(tuple), detail::IntRange<sizeof...(Args)>());
+}
+
+template <class F, class... Args>
+void tuple_for_each(std::tuple<Args...> &tuple, const F &func) {
+  detail::tuple_for_each_impl(tuple, func, detail::IntRange<sizeof...(Args)>());
+}
+
+template <class F, class... Args>
+void tuple_for_each(const std::tuple<Args...> &tuple, const F &func) {
+  detail::tuple_for_each_impl(tuple, func, detail::IntRange<sizeof...(Args)>());
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/logging.cpp b/libs/tdlib/td/tdutils/td/utils/logging.cpp
new file mode 100644
index 0000000000..17403ff87b
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/logging.cpp
@@ -0,0 +1,238 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/logging.h"
+
+#include "td/utils/port/Clocks.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/thread_local.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Time.h"
+
+#include <atomic>
+#include <cstdlib>
+
+#if TD_ANDROID
+#include <android/log.h>
+#define ALOG_TAG "DLTD"
+#elif TD_TIZEN
+#include <dlog.h>
+#define DLOG_TAG "DLTD"
+#elif TD_EMSCRIPTEN
+#include <emscripten.h>
+#endif
+
+namespace td {
+
+int VERBOSITY_NAME(level) = VERBOSITY_NAME(DEBUG) + 1;
+int VERBOSITY_NAME(net_query) = VERBOSITY_NAME(INFO);
+int VERBOSITY_NAME(td_requests) = VERBOSITY_NAME(INFO);
+int VERBOSITY_NAME(dc) = VERBOSITY_NAME(DEBUG) + 2;
+int VERBOSITY_NAME(files) = VERBOSITY_NAME(DEBUG) + 2;
+int VERBOSITY_NAME(mtproto) = VERBOSITY_NAME(DEBUG) + 7;
+int VERBOSITY_NAME(connections) = VERBOSITY_NAME(DEBUG) + 8;
+int VERBOSITY_NAME(raw_mtproto) = VERBOSITY_NAME(DEBUG) + 10;
+int VERBOSITY_NAME(fd) = VERBOSITY_NAME(DEBUG) + 9;
+int VERBOSITY_NAME(actor) = VERBOSITY_NAME(DEBUG) + 10;
+int VERBOSITY_NAME(buffer) = VERBOSITY_NAME(DEBUG) + 10;
+int VERBOSITY_NAME(sqlite) = VERBOSITY_NAME(DEBUG) + 10;
+
+TD_THREAD_LOCAL const char *Logger::tag_ = nullptr;
+TD_THREAD_LOCAL const char *Logger::tag2_ = nullptr;
+
+Logger::Logger(LogInterface &log, int log_level, Slice file_name, int line_num, Slice comment, bool simple_mode)
+    : Logger(log, log_level, simple_mode) {
+  if (simple_mode) {
+    return;
+  }
+
+  auto last_slash_ = static_cast<int32>(file_name.size()) - 1;
+  while (last_slash_ >= 0 && file_name[last_slash_] != '/' && file_name[last_slash_] != '\\') {
+    last_slash_--;
+  }
+  file_name = file_name.substr(last_slash_ + 1);
+
+  auto thread_id = get_thread_id();
+
+  (*this) << '[';
+  if (log_level < 10) {
+    (*this) << ' ';
+  }
+  (*this) << log_level << "][t";
+  if (thread_id < 10) {
+    (*this) << ' ';
+  }
+  (*this) << thread_id << "][" << StringBuilder::FixedDouble(Clocks::system(), 9) << "][" << file_name << ':'
+          << line_num << ']';
+  if (tag_ != nullptr && *tag_) {
+    (*this) << "[#" << Slice(tag_) << "]";
+  }
+  if (tag2_ != nullptr && *tag2_) {
+    (*this) << "[!" << Slice(tag2_) << "]";
+  }
+  if (!comment.empty()) {
+    (*this) << "[&" << comment << "]";
+  }
+  (*this) << "\t";
+}
+
+Logger::~Logger() {
+  if (!simple_mode_) {
+    sb_ << '\n';
+    auto slice = as_cslice();
+    if (slice.back() != '\n') {
+      slice.back() = '\n';
+    }
+  }
+
+  log_.append(as_cslice(), log_level_);
+}
+
+TsCerr::TsCerr() {
+  enterCritical();
+}
+TsCerr::~TsCerr() {
+  exitCritical();
+}
+TsCerr &TsCerr::operator<<(Slice slice) {
+  auto &fd = Fd::Stderr();
+  if (fd.empty()) {
+    return *this;
+  }
+  double end_time = 0;
+  while (!slice.empty()) {
+    auto res = fd.write(slice);
+    if (res.is_error()) {
+      if (res.error().code() == EPIPE) {
+        break;
+      }
+      // Resource temporary unavailable
+      if (end_time == 0) {
+        end_time = Time::now() + 0.01;
+      } else if (Time::now() > end_time) {
+        break;
+      }
+      continue;
+    }
+    slice.remove_prefix(res.ok());
+  }
+  return *this;
+}
+
+void TsCerr::enterCritical() {
+  while (lock_.test_and_set(std::memory_order_acquire)) {
+    // spin
+  }
+}
+
+void TsCerr::exitCritical() {
+  lock_.clear(std::memory_order_release);
+}
+TsCerr::Lock TsCerr::lock_ = ATOMIC_FLAG_INIT;
+
+class DefaultLog : public LogInterface {
+ public:
+  void append(CSlice slice, int log_level) override {
+#if TD_ANDROID
+    switch (log_level) {
+      case VERBOSITY_NAME(FATAL):
+        __android_log_write(ANDROID_LOG_FATAL, ALOG_TAG, slice.c_str());
+        break;
+      case VERBOSITY_NAME(ERROR):
+        __android_log_write(ANDROID_LOG_ERROR, ALOG_TAG, slice.c_str());
+        break;
+      case VERBOSITY_NAME(WARNING):
+        __android_log_write(ANDROID_LOG_WARN, ALOG_TAG, slice.c_str());
+        break;
+      case VERBOSITY_NAME(INFO):
+        __android_log_write(ANDROID_LOG_INFO, ALOG_TAG, slice.c_str());
+        break;
+      default:
+        __android_log_write(ANDROID_LOG_DEBUG, ALOG_TAG, slice.c_str());
+        break;
+    }
+#elif TD_TIZEN
+    switch (log_level) {
+      case VERBOSITY_NAME(FATAL):
+        dlog_print(DLOG_ERROR, DLOG_TAG, slice.c_str());
+        break;
+      case VERBOSITY_NAME(ERROR):
+        dlog_print(DLOG_ERROR, DLOG_TAG, slice.c_str());
+        break;
+      case VERBOSITY_NAME(WARNING):
+        dlog_print(DLOG_WARN, DLOG_TAG, slice.c_str());
+        break;
+      case VERBOSITY_NAME(INFO):
+        dlog_print(DLOG_INFO, DLOG_TAG, slice.c_str());
+        break;
+      default:
+        dlog_print(DLOG_DEBUG, DLOG_TAG, slice.c_str());
+        break;
+    }
+#elif TD_EMSCRIPTEN
+    switch (log_level) {
+      case VERBOSITY_NAME(FATAL):
+        emscripten_log(
+            EM_LOG_ERROR | EM_LOG_CONSOLE | EM_LOG_C_STACK | EM_LOG_JS_STACK | EM_LOG_DEMANGLE | EM_LOG_FUNC_PARAMS,
+            "%s", slice.c_str());
+        EM_ASM(throw(UTF8ToString($0)), slice.c_str());
+        break;
+      case VERBOSITY_NAME(ERROR):
+        emscripten_log(EM_LOG_ERROR | EM_LOG_CONSOLE, "%s", slice.c_str());
+        break;
+      case VERBOSITY_NAME(WARNING):
+        emscripten_log(EM_LOG_WARN | EM_LOG_CONSOLE, "%s", slice.c_str());
+        break;
+      default:
+        emscripten_log(EM_LOG_CONSOLE, "%s", slice.c_str());
+        break;
+    }
+#elif !TD_WINDOWS
+    Slice color;
+    switch (log_level) {
+      case VERBOSITY_NAME(FATAL):
+      case VERBOSITY_NAME(ERROR):
+        color = TC_RED;
+        break;
+      case VERBOSITY_NAME(WARNING):
+        color = TC_YELLOW;
+        break;
+      case VERBOSITY_NAME(INFO):
+        color = TC_CYAN;
+        break;
+    }
+    TsCerr() << color << slice << TC_EMPTY;
+#else
+    // TODO: color
+    TsCerr() << slice;
+#endif
+    if (log_level == VERBOSITY_NAME(FATAL)) {
+      process_fatal_error(slice);
+    }
+  }
+  void rotate() override {
+  }
+};
+static DefaultLog default_log;
+
+LogInterface *const default_log_interface = &default_log;
+LogInterface *log_interface = default_log_interface;
+
+static OnFatalErrorCallback on_fatal_error_callback = nullptr;
+
+void set_log_fatal_error_callback(OnFatalErrorCallback callback) {
+  on_fatal_error_callback = callback;
+}
+
+void process_fatal_error(CSlice message) {
+  auto callback = on_fatal_error_callback;
+  if (callback) {
+    callback(message);
+  }
+  std::abort();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/logging.h b/libs/tdlib/td/tdutils/td/utils/logging.h
new file mode 100644
index 0000000000..629a4f248a
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/logging.h
@@ -0,0 +1,279 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+/*
+ * Simple logging.
+ *
+ * Predefined log levels: FATAL, ERROR, WARNING, INFO, DEBUG
+ *
+ * LOG(WARNING) << "Hello world!";
+ * LOG(INFO) << "Hello " << 1234 << " world!";
+ * LOG_IF(INFO, condition) << "Hello world if condition!";
+ *
+ * Custom log levels may be defined and used using VLOG:
+ * int VERBOSITY_NAME(custom) = VERBOSITY_NAME(WARNING);
+ * VLOG(custom) << "Hello custom world!"
+ *
+ * LOG(FATAL) << "Power is off";
+ * CHECK(condition) <===> LOG_IF(FATAL, !(condition))
+ */
+
+#include "td/utils/common.h"
+#include "td/utils/port/thread_local.h"
+#include "td/utils/Slice-decl.h"
+#include "td/utils/StackAllocator.h"
+#include "td/utils/StringBuilder.h"
+
+#include <atomic>
+#include <type_traits>
+
+#define PSTR_IMPL() ::td::Logger(::td::NullLog().ref(), 0, true)
+#define PSLICE() ::td::detail::Slicify() & PSTR_IMPL()
+#define PSTRING() ::td::detail::Stringify() & PSTR_IMPL()
+#define PSLICE_SAFE() ::td::detail::SlicifySafe() & PSTR_IMPL()
+#define PSTRING_SAFE() ::td::detail::StringifySafe() & PSTR_IMPL()
+
+#define VERBOSITY_NAME(x) verbosity_##x
+
+#define GET_VERBOSITY_LEVEL() (::td::VERBOSITY_NAME(level))
+#define SET_VERBOSITY_LEVEL(new_level) (::td::VERBOSITY_NAME(level) = (new_level))
+
+#ifndef STRIP_LOG
+#define STRIP_LOG VERBOSITY_NAME(DEBUG)
+#endif
+#define LOG_IS_STRIPPED(strip_level) \
+  (std::integral_constant<int, VERBOSITY_NAME(strip_level)>() > std::integral_constant<int, STRIP_LOG>())
+
+#define LOGGER(level, comment)                                                           \
+  ::td::Logger(*::td::log_interface, VERBOSITY_NAME(level), __FILE__, __LINE__, comment, \
+               VERBOSITY_NAME(level) == VERBOSITY_NAME(PLAIN))
+
+#define LOG_IMPL(strip_level, level, condition, comment)                                        \
+  LOG_IS_STRIPPED(strip_level) || VERBOSITY_NAME(level) > GET_VERBOSITY_LEVEL() || !(condition) \
+      ? (void)0                                                                                 \
+      : ::td::detail::Voidify() & LOGGER(level, comment)
+
+#define LOG(level) LOG_IMPL(level, level, true, ::td::Slice())
+#define LOG_IF(level, condition) LOG_IMPL(level, level, condition, #condition)
+
+#define VLOG(level) LOG_IMPL(DEBUG, level, true, TD_DEFINE_STR(level))
+#define VLOG_IF(level, condition) LOG_IMPL(DEBUG, level, condition, TD_DEFINE_STR(level) " " #condition)
+
+#define LOG_ROTATE() ::td::log_interface->rotate()
+
+#define LOG_TAG ::td::Logger::tag_
+#define LOG_TAG2 ::td::Logger::tag2_
+
+#if TD_CLANG
+bool no_return_func() __attribute__((analyzer_noreturn));
+#endif
+
+inline bool no_return_func() {
+  return true;
+}
+
+// clang-format off
+#ifdef CHECK
+  #undef CHECK
+#endif
+#ifdef TD_DEBUG
+  #if TD_MSVC
+    #define CHECK(condition)            \
+      __analysis_assume(!!(condition)); \
+      LOG_IMPL(FATAL, FATAL, !(condition), #condition)
+  #else
+    #define CHECK(condition) LOG_IMPL(FATAL, FATAL, !(condition) && no_return_func(), #condition)
+  #endif
+#else
+  #define CHECK(condition) LOG_IF(NEVER, !(condition))
+#endif
+// clang-format on
+
+#define UNREACHABLE() \
+  LOG(FATAL);         \
+  ::td::process_fatal_error("Unreachable in " __FILE__ " at " TD_DEFINE_STR(__LINE__))
+
+constexpr int VERBOSITY_NAME(PLAIN) = -1;
+constexpr int VERBOSITY_NAME(FATAL) = 0;
+constexpr int VERBOSITY_NAME(ERROR) = 1;
+constexpr int VERBOSITY_NAME(WARNING) = 2;
+constexpr int VERBOSITY_NAME(INFO) = 3;
+constexpr int VERBOSITY_NAME(DEBUG) = 4;
+constexpr int VERBOSITY_NAME(NEVER) = 1024;
+
+namespace td {
+extern int VERBOSITY_NAME(level);
+// TODO Not part of utils. Should be in some separate file
+extern int VERBOSITY_NAME(mtproto);
+extern int VERBOSITY_NAME(raw_mtproto);
+extern int VERBOSITY_NAME(connections);
+extern int VERBOSITY_NAME(dc);
+extern int VERBOSITY_NAME(fd);
+extern int VERBOSITY_NAME(net_query);
+extern int VERBOSITY_NAME(td_requests);
+extern int VERBOSITY_NAME(actor);
+extern int VERBOSITY_NAME(buffer);
+extern int VERBOSITY_NAME(files);
+extern int VERBOSITY_NAME(sqlite);
+
+class LogInterface {
+ public:
+  LogInterface() = default;
+  LogInterface(const LogInterface &) = delete;
+  LogInterface &operator=(const LogInterface &) = delete;
+  LogInterface(LogInterface &&) = delete;
+  LogInterface &operator=(LogInterface &&) = delete;
+  virtual ~LogInterface() = default;
+  virtual void append(CSlice slice, int log_level_) = 0;
+  virtual void rotate() = 0;
+};
+
+class NullLog : public LogInterface {
+ public:
+  void append(CSlice slice, int log_level_) override {
+  }
+  void rotate() override {
+  }
+  NullLog &ref() {
+    return *this;
+  }
+};
+
+extern LogInterface *const default_log_interface;
+extern LogInterface *log_interface;
+
+using OnFatalErrorCallback = void (*)(CSlice message);
+void set_log_fatal_error_callback(OnFatalErrorCallback callback);
+
+[[noreturn]] void process_fatal_error(CSlice message);
+
+#define TC_RED "\e[1;31m"
+#define TC_BLUE "\e[1;34m"
+#define TC_CYAN "\e[1;36m"
+#define TC_GREEN "\e[1;32m"
+#define TC_YELLOW "\e[1;33m"
+#define TC_EMPTY "\e[0m"
+
+class TsCerr {
+ public:
+  TsCerr();
+  TsCerr(const TsCerr &) = delete;
+  TsCerr &operator=(const TsCerr &) = delete;
+  TsCerr(TsCerr &&) = delete;
+  TsCerr &operator=(TsCerr &&) = delete;
+  ~TsCerr();
+  TsCerr &operator<<(Slice slice);
+
+ private:
+  using Lock = std::atomic_flag;
+  static Lock lock_;
+
+  void enterCritical();
+  void exitCritical();
+};
+
+class Logger {
+ public:
+  static const int BUFFER_SIZE = 128 * 1024;
+  Logger(LogInterface &log, int log_level, bool simple_mode = false)
+      : buffer_(StackAllocator::alloc(BUFFER_SIZE))
+      , log_(log)
+      , log_level_(log_level)
+      , sb_(buffer_.as_slice())
+      , simple_mode_(simple_mode) {
+  }
+
+  Logger(LogInterface &log, int log_level, Slice file_name, int line_num, Slice comment, bool simple_mode);
+
+  template <class T>
+  Logger &operator<<(const T &other) {
+    sb_ << other;
+    return *this;
+  }
+
+  MutableCSlice as_cslice() {
+    return sb_.as_cslice();
+  }
+  bool is_error() const {
+    return sb_.is_error();
+  }
+  Logger(const Logger &) = delete;
+  Logger &operator=(const Logger &) = delete;
+  Logger(Logger &&) = delete;
+  Logger &operator=(Logger &&) = delete;
+  ~Logger();
+
+  static TD_THREAD_LOCAL const char *tag_;
+  static TD_THREAD_LOCAL const char *tag2_;
+
+ private:
+  decltype(StackAllocator::alloc(0)) buffer_;
+  LogInterface &log_;
+  int log_level_;
+  StringBuilder sb_;
+  bool simple_mode_;
+};
+
+namespace detail {
+class Voidify {
+ public:
+  template <class T>
+  void operator&(const T &) {
+  }
+};
+
+class Slicify {
+ public:
+  CSlice operator&(Logger &logger) {
+    return logger.as_cslice();
+  }
+};
+
+class Stringify {
+ public:
+  string operator&(Logger &logger) {
+    return logger.as_cslice().str();
+  }
+};
+}  // namespace detail
+
+class TsLog : public LogInterface {
+ public:
+  explicit TsLog(LogInterface *log) : log_(log) {
+  }
+  void init(LogInterface *log) {
+    enter_critical();
+    log_ = log;
+    exit_critical();
+  }
+  void append(CSlice slice, int level) override {
+    enter_critical();
+    log_->append(slice, level);
+    exit_critical();
+  }
+  void rotate() override {
+    enter_critical();
+    log_->rotate();
+    exit_critical();
+  }
+
+ private:
+  LogInterface *log_ = nullptr;
+  std::atomic_flag lock_ = ATOMIC_FLAG_INIT;
+  void enter_critical() {
+    while (lock_.test_and_set(std::memory_order_acquire)) {
+      // spin
+    }
+  }
+  void exit_critical() {
+    lock_.clear(std::memory_order_release);
+  }
+};
+}  // namespace td
+
+#include "td/utils/Slice.h"
diff --git a/libs/tdlib/td/tdutils/td/utils/misc.cpp b/libs/tdlib/td/tdutils/td/utils/misc.cpp
new file mode 100644
index 0000000000..f3068ca6d3
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/misc.cpp
@@ -0,0 +1,78 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/misc.h"
+
+#include "td/utils/port/thread_local.h"
+
+#include <algorithm>
+#include <cstdlib>
+#include <locale>
+#include <sstream>
+
+namespace td {
+
+char *str_dup(Slice str) {
+  char *res = static_cast<char *>(std::malloc(str.size() + 1));
+  if (res == nullptr) {
+    return nullptr;
+  }
+  std::copy(str.begin(), str.end(), res);
+  res[str.size()] = '\0';
+  return res;
+}
+
+string implode(vector<string> v, char delimiter) {
+  string result;
+  for (auto &str : v) {
+    if (!result.empty()) {
+      result += delimiter;
+    }
+    result += str;
+  }
+  return result;
+}
+
+string oneline(Slice str) {
+  string result;
+  result.reserve(str.size());
+  bool after_new_line = true;
+  for (auto c : str) {
+    if (c != '\n') {
+      if (after_new_line) {
+        if (c == ' ') {
+          continue;
+        }
+        after_new_line = false;
+      }
+      result += c;
+    } else {
+      after_new_line = true;
+      result += ' ';
+    }
+  }
+  while (!result.empty() && result.back() == ' ') {
+    result.pop_back();
+  }
+  return result;
+}
+
+double to_double(Slice str) {
+  static TD_THREAD_LOCAL std::stringstream *ss;
+  if (init_thread_local<std::stringstream>(ss)) {
+    ss->imbue(std::locale::classic());
+  } else {
+    ss->str(std::string());
+    ss->clear();
+  }
+  ss->write(str.begin(), narrow_cast<std::streamsize>(str.size()));
+
+  double result = 0.0;
+  *ss >> result;
+  return result;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/misc.h b/libs/tdlib/td/tdutils/td/utils/misc.h
new file mode 100644
index 0000000000..62b01794ab
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/misc.h
@@ -0,0 +1,337 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+
+#include <cstdint>
+#include <limits>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+
+namespace td {
+
+char *str_dup(Slice str);
+
+template <class T>
+std::pair<T, T> split(T s, char delimiter = ' ') {
+  auto delimiter_pos = s.find(delimiter);
+  if (delimiter_pos == string::npos) {
+    return {std::move(s), T()};
+  } else {
+    return {s.substr(0, delimiter_pos), s.substr(delimiter_pos + 1)};
+  }
+}
+
+template <class T>
+vector<T> full_split(T s, char delimiter = ' ') {
+  T next;
+  vector<T> result;
+  while (!s.empty()) {
+    std::tie(next, s) = split(s, delimiter);
+    result.push_back(next);
+  }
+  return result;
+}
+
+string implode(vector<string> v, char delimiter = ' ');
+
+namespace detail {
+
+template <typename T>
+struct transform_helper {
+  template <class Func>
+  auto transform(const T &v, const Func &f) {
+    vector<decltype(f(*v.begin()))> result;
+    result.reserve(v.size());
+    for (auto &x : v) {
+      result.push_back(f(x));
+    }
+    return result;
+  }
+
+  template <class Func>
+  auto transform(T &&v, const Func &f) {
+    vector<decltype(f(std::move(*v.begin())))> result;
+    result.reserve(v.size());
+    for (auto &x : v) {
+      result.push_back(f(std::move(x)));
+    }
+    return result;
+  }
+};
+
+}  // namespace detail
+
+template <class T, class Func>
+auto transform(T &&v, const Func &f) {
+  return detail::transform_helper<std::decay_t<T>>().transform(std::forward<T>(v), f);
+}
+
+template <class T>
+void reset_to_empty(T &value) {
+  using std::swap;
+  std::decay_t<T> tmp;
+  swap(tmp, value);
+}
+
+template <class T>
+auto append(vector<T> &destination, const vector<T> &source) {
+  destination.insert(destination.end(), source.begin(), source.end());
+}
+
+template <class T>
+auto append(vector<T> &destination, vector<T> &&source) {
+  if (destination.empty()) {
+    destination.swap(source);
+    return;
+  }
+  destination.reserve(destination.size() + source.size());
+  for (auto &elem : source) {
+    destination.push_back(std::move(elem));
+  }
+  reset_to_empty(source);
+}
+
+inline bool begins_with(Slice str, Slice prefix) {
+  return prefix.size() <= str.size() && prefix == Slice(str.data(), prefix.size());
+}
+
+inline bool ends_with(Slice str, Slice suffix) {
+  return suffix.size() <= str.size() && suffix == Slice(str.data() + str.size() - suffix.size(), suffix.size());
+}
+
+inline char to_lower(char c) {
+  if ('A' <= c && c <= 'Z') {
+    return static_cast<char>(c - 'A' + 'a');
+  }
+
+  return c;
+}
+
+inline void to_lower_inplace(MutableSlice slice) {
+  for (auto &c : slice) {
+    c = to_lower(c);
+  }
+}
+
+inline string to_lower(Slice slice) {
+  auto result = slice.str();
+  to_lower_inplace(result);
+  return result;
+}
+
+inline char to_upper(char c) {
+  if ('a' <= c && c <= 'z') {
+    return static_cast<char>(c - 'a' + 'A');
+  }
+
+  return c;
+}
+
+inline void to_upper_inplace(MutableSlice slice) {
+  for (auto &c : slice) {
+    c = to_upper(c);
+  }
+}
+
+inline string to_upper(Slice slice) {
+  auto result = slice.str();
+  to_upper_inplace(result);
+  return result;
+}
+
+inline bool is_space(char c) {
+  return c == ' ' || c == '\t' || c == '\r' || c == '\n' || c == '\0' || c == '\v';
+}
+
+inline bool is_alpha(char c) {
+  c |= 0x20;
+  return 'a' <= c && c <= 'z';
+}
+
+inline bool is_digit(char c) {
+  return '0' <= c && c <= '9';
+}
+
+inline bool is_alnum(char c) {
+  return is_alpha(c) || is_digit(c);
+}
+
+inline bool is_hex_digit(char c) {
+  if (is_digit(c)) {
+    return true;
+  }
+  c |= 0x20;
+  return 'a' <= c && c <= 'f';
+}
+
+template <class T>
+T trim(T str) {
+  auto begin = str.data();
+  auto end = begin + str.size();
+  while (begin < end && is_space(*begin)) {
+    begin++;
+  }
+  while (begin < end && is_space(end[-1])) {
+    end--;
+  }
+  if (static_cast<size_t>(end - begin) == str.size()) {
+    return std::move(str);
+  }
+  return T(begin, end);
+}
+
+string oneline(Slice str);
+
+template <class T>
+std::enable_if_t<std::is_signed<T>::value, T> to_integer(Slice str) {
+  using unsigned_T = typename std::make_unsigned<T>::type;
+  unsigned_T integer_value = 0;
+  auto begin = str.begin();
+  auto end = str.end();
+  bool is_negative = false;
+  if (begin != end && *begin == '-') {
+    is_negative = true;
+    begin++;
+  }
+  while (begin != end && is_digit(*begin)) {
+    integer_value = static_cast<unsigned_T>(integer_value * 10 + (*begin++ - '0'));
+  }
+  if (integer_value > static_cast<unsigned_T>(std::numeric_limits<T>::max())) {
+    static_assert(~0 + 1 == 0, "Two's complement");
+    // Use ~x + 1 instead of -x to suppress Visual Studio warning.
+    integer_value = static_cast<unsigned_T>(~integer_value + 1);
+    is_negative = !is_negative;
+
+    if (integer_value > static_cast<unsigned_T>(std::numeric_limits<T>::max())) {
+      return std::numeric_limits<T>::min();
+    }
+  }
+
+  return is_negative ? static_cast<T>(-static_cast<T>(integer_value)) : static_cast<T>(integer_value);
+}
+
+template <class T>
+std::enable_if_t<std::is_unsigned<T>::value, T> to_integer(Slice str) {
+  T integer_value = 0;
+  auto begin = str.begin();
+  auto end = str.end();
+  while (begin != end && is_digit(*begin)) {
+    integer_value = static_cast<T>(integer_value * 10 + (*begin++ - '0'));
+  }
+  return integer_value;
+}
+
+template <class T>
+Result<T> to_integer_safe(Slice str) {
+  auto res = to_integer<T>(str);
+  if (to_string(res) != str) {
+    return Status::Error(PSLICE() << "Can't parse \"" << str << "\" as number");
+  }
+  return res;
+}
+
+inline int hex_to_int(char c) {
+  if (is_digit(c)) {
+    return c - '0';
+  }
+  c |= 0x20;
+  if ('a' <= c && c <= 'f') {
+    return c - 'a' + 10;
+  }
+  return 16;
+}
+
+template <class T>
+typename std::enable_if<std::is_unsigned<T>::value, T>::type hex_to_integer(Slice str) {
+  T integer_value = 0;
+  auto begin = str.begin();
+  auto end = str.end();
+  while (begin != end && is_hex_digit(*begin)) {
+    integer_value = static_cast<T>(integer_value * 16 + hex_to_int(*begin++));
+  }
+  return integer_value;
+}
+
+double to_double(Slice str);
+
+template <class T>
+T clamp(T value, T min_value, T max_value) {
+  if (value < min_value) {
+    return min_value;
+  }
+  if (value > max_value) {
+    return max_value;
+  }
+  return value;
+}
+
+// run-time checked narrowing cast (type conversion):
+
+namespace detail {
+template <class T, class U>
+struct is_same_signedness
+    : public std::integral_constant<bool, std::is_signed<T>::value == std::is_signed<U>::value> {};
+
+template <class T, class Enable = void>
+struct safe_undeflying_type {
+  using type = T;
+};
+
+template <class T>
+struct safe_undeflying_type<T, std::enable_if_t<std::is_enum<T>::value>> {
+  using type = std::underlying_type_t<T>;
+};
+}  // namespace detail
+
+template <class R, class A>
+R narrow_cast(const A &a) {
+  using RT = typename detail::safe_undeflying_type<R>::type;
+  using AT = typename detail::safe_undeflying_type<A>::type;
+
+  static_assert(std::is_integral<RT>::value, "expected integral type to cast to");
+  static_assert(std::is_integral<AT>::value, "expected integral type to cast from");
+
+  auto r = R(a);
+  CHECK(A(r) == a);
+  CHECK((detail::is_same_signedness<RT, AT>::value) || ((static_cast<RT>(r) < RT{}) == (static_cast<AT>(a) < AT{})));
+
+  return r;
+}
+
+template <class R, class A>
+Result<R> narrow_cast_safe(const A &a) {
+  using RT = typename detail::safe_undeflying_type<R>::type;
+  using AT = typename detail::safe_undeflying_type<A>::type;
+
+  static_assert(std::is_integral<RT>::value, "expected integral type to cast to");
+  static_assert(std::is_integral<AT>::value, "expected integral type to cast from");
+
+  auto r = R(a);
+  if (!(A(r) == a)) {
+    return Status::Error("Narrow cast failed");
+  }
+  if (!((detail::is_same_signedness<RT, AT>::value) || ((static_cast<RT>(r) < RT{}) == (static_cast<AT>(a) < AT{})))) {
+    return Status::Error("Narrow cast failed");
+  }
+
+  return r;
+}
+
+template <int Alignment, class T>
+bool is_aligned_pointer(const T *pointer) {
+  static_assert(Alignment > 0 && (Alignment & (Alignment - 1)) == 0, "Wrong alignment");
+  return (reinterpret_cast<std::uintptr_t>(static_cast<const void *>(pointer)) & (Alignment - 1)) == 0;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/optional.h b/libs/tdlib/td/tdutils/td/utils/optional.h
new file mode 100644
index 0000000000..450b60f94c
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/optional.h
@@ -0,0 +1,36 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/Status.h"
+
+#include <utility>
+
+namespace td {
+
+template <class T>
+class optional {
+ public:
+  optional() = default;
+  template <class T1>
+  optional(T1 &&t) : impl_(std::forward<T1>(t)) {
+  }
+  explicit operator bool() {
+    return impl_.is_ok();
+  }
+  T &value() {
+    return impl_.ok_ref();
+  }
+  T &operator*() {
+    return value();
+  }
+
+ private:
+  Result<T> impl_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/overloaded.h b/libs/tdlib/td/tdutils/td/utils/overloaded.h
new file mode 100644
index 0000000000..6c6186f6a2
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/overloaded.h
@@ -0,0 +1,39 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+namespace td {
+
+namespace detail {
+
+template <class... Fs>
+struct overload;
+
+template <class F>
+struct overload<F> : public F {
+  explicit overload(F f) : F(f) {
+  }
+};
+
+template <class F, class... Fs>
+struct overload<F, Fs...>
+    : public overload<F>
+    , overload<Fs...> {
+  overload(F f, Fs... fs) : overload<F>(f), overload<Fs...>(fs...) {
+  }
+  using overload<F>::operator();
+  using overload<Fs...>::operator();
+};
+
+}  // namespace detail
+
+template <class... F>
+auto overloaded(F... f) {
+  return detail::overload<F...>(f...);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/Clocks.cpp b/libs/tdlib/td/tdutils/td/utils/port/Clocks.cpp
new file mode 100644
index 0000000000..da68754a61
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/Clocks.cpp
@@ -0,0 +1,23 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/Clocks.h"
+
+#include <chrono>
+
+namespace td {
+
+ClocksDefault::Duration ClocksDefault::monotonic() {
+  auto duration = std::chrono::steady_clock::now().time_since_epoch();
+  return static_cast<double>(std::chrono::duration_cast<std::chrono::nanoseconds>(duration).count()) * 1e-9;
+}
+
+ClocksDefault::Duration ClocksDefault::system() {
+  auto duration = std::chrono::system_clock::now().time_since_epoch();
+  return static_cast<double>(std::chrono::duration_cast<std::chrono::nanoseconds>(duration).count()) * 1e-9;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/Clocks.h b/libs/tdlib/td/tdutils/td/utils/port/Clocks.h
new file mode 100644
index 0000000000..a4270df4ad
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/Clocks.h
@@ -0,0 +1,28 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+namespace td {
+
+class ClocksBase {
+ public:
+  using Duration = double;
+};
+
+// TODO: (maybe) write system specific functions.
+class ClocksDefault {
+ public:
+  using Duration = ClocksBase::Duration;
+
+  static Duration monotonic();
+
+  static Duration system();
+};
+
+using Clocks = ClocksDefault;
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/CxCli.h b/libs/tdlib/td/tdutils/td/utils/port/CxCli.h
new file mode 100644
index 0000000000..b7f01fa401
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/CxCli.h
@@ -0,0 +1,133 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#include "td/utils/common.h"
+#undef small
+
+#if TD_WINRT
+
+#include "td/utils/port/wstring_convert.h"
+
+#include "collection.h"
+
+#include <cstdint>
+#include <map>
+#include <mutex>
+
+#define REF_NEW ref new
+#define CLRCALL
+
+namespace CxCli {
+
+using Windows::Foundation::Collections::IVector;
+#define Array IVector
+using Platform::Collections::Vector;
+#define ArraySize(arr) ((arr)->Size)
+#define ArrayGet(arr, index) ((arr)->GetAt(index))
+#define ArraySet(arr, index, value) ((arr)->SetAt((index), (value)))
+#define ArrayIndexType unsigned
+
+using Platform::String;
+
+using Platform::NullReferenceException;
+
+template <class Key, class Value> class ConcurrentDictionary {
+public:
+  bool TryGetValue(Key key, Value &value) {
+    std::lock_guard<std::mutex> guard(mutex_);
+    auto it = impl_.find(key);
+    if (it == impl_.end()) {
+      return false;
+    }
+    value = it->second;
+    return true;
+  }
+  bool TryRemove(Key key, Value &value) {
+    std::lock_guard<std::mutex> guard(mutex_);
+    auto it = impl_.find(key);
+    if (it == impl_.end()) {
+      return false;
+    }
+    value = std::move(it->second);
+    impl_.erase(it);
+    return true;
+  }
+  Value &operator [] (Key key) {
+    std::lock_guard<std::mutex> guard(mutex_);
+    return impl_[key];
+  }
+private:
+  std::mutex mutex_;
+  std::map<Key, Value> impl_;
+};
+
+inline std::int64_t Increment(volatile std::int64_t &value) {
+  return InterlockedIncrement64(&value);
+}
+
+inline std::string string_to_unmanaged(String^ str) {
+  if (!str) {
+    return std::string();
+  }
+  return td::from_wstring(str->Data(), str->Length()).ok();
+}
+
+inline String^ string_from_unmanaged(const std::string &from) {
+  auto tmp = td::to_wstring(from).ok();
+  return REF_NEW String(tmp.c_str(), static_cast<unsigned>(tmp.size()));
+}
+
+} // namespace CxCli
+
+#elif TD_CLI
+
+#include <msclr\marshal_cppstd.h>
+
+#define REF_NEW gcnew
+#define CLRCALL __clrcall
+
+namespace CxCli {
+
+using uint8 = td::uint8;
+using int32 = td::int32;
+using int64 = td::int64;
+using float64 = double;
+
+#define Array array
+#define Vector array
+#define ArraySize(arr) ((arr)->Length)
+#define ArrayGet(arr, index) ((arr)[index])
+#define ArraySet(arr, index, value) ((arr)[index] = (value))
+#define ArrayIndexType int
+
+using System::String;
+
+using System::NullReferenceException;
+
+using System::Collections::Concurrent::ConcurrentDictionary;
+
+inline std::int64_t Increment(std::int64_t %value) {
+  return System::Threading::Interlocked::Increment(value);
+}
+
+inline std::string string_to_unmanaged(String^ str) {
+  if (!str) {
+    return std::string();
+  }
+  return msclr::interop::marshal_as<std::string>(str);
+}
+
+inline String^ string_from_unmanaged(const std::string &from) {
+  return msclr::interop::marshal_as<String^>(from);
+}
+
+} // namespace CxCli
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/EventFd.h b/libs/tdlib/td/tdutils/td/utils/port/EventFd.h
new file mode 100644
index 0000000000..ba2edabefd
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/EventFd.h
@@ -0,0 +1,33 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+// include all and let config.h decide
+#include "td/utils/port/detail/EventFdBsd.h"
+#include "td/utils/port/detail/EventFdLinux.h"
+#include "td/utils/port/detail/EventFdWindows.h"
+
+namespace td {
+
+// clang-format off
+
+#if TD_EVENTFD_LINUX
+  using EventFd = detail::EventFdLinux;
+#elif TD_EVENTFD_BSD
+  using EventFd = detail::EventFdBsd;
+#elif TD_EVENTFD_WINDOWS
+  using EventFd = detail::EventFdWindows;
+#elif TD_EVENTFD_UNSUPPORTED
+#else
+  #error "EventFd's implementation is not defined"
+#endif
+
+// clang-format on
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/EventFdBase.h b/libs/tdlib/td/tdutils/td/utils/port/EventFdBase.h
new file mode 100644
index 0000000000..e119a3c0eb
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/EventFdBase.h
@@ -0,0 +1,32 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/Status.h"
+
+namespace td {
+class EventFdBase {
+ public:
+  EventFdBase() = default;
+  EventFdBase(const EventFdBase &) = delete;
+  EventFdBase &operator=(const EventFdBase &) = delete;
+  EventFdBase(EventFdBase &&) = default;
+  EventFdBase &operator=(EventFdBase &&) = default;
+  virtual ~EventFdBase() = default;
+
+  virtual void init() = 0;
+  virtual bool empty() = 0;
+  virtual void close() = 0;
+  virtual const Fd &get_fd() const = 0;
+  virtual Fd &get_fd() = 0;
+  virtual Status get_pending_error() TD_WARN_UNUSED_RESULT = 0;
+  virtual void release() = 0;
+  virtual void acquire() = 0;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/Fd.cpp b/libs/tdlib/td/tdutils/td/utils/port/Fd.cpp
new file mode 100644
index 0000000000..cb4cb27306
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/Fd.cpp
@@ -0,0 +1,1104 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/Fd.h"
+
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Observer.h"
+
+#if TD_PORT_POSIX
+
+#include <atomic>
+
+#include <fcntl.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#endif
+
+#if TD_PORT_WINDOWS
+
+#include "td/utils/buffer.h"
+#include "td/utils/misc.h"
+
+#include <cstring>
+
+#endif
+
+namespace td {
+
+#if TD_PORT_POSIX
+
+Fd::InfoSet::InfoSet() {
+  get_info(0).refcnt = 1;
+  get_info(1).refcnt = 1;
+  get_info(2).refcnt = 1;
+}
+Fd::Info &Fd::InfoSet::get_info(int32 id) {
+  CHECK(0 <= id && id < InfoSet::MAX_FD) << tag("fd", id);
+  return fd_array_[id];
+}
+Fd::InfoSet Fd::fd_info_set_;
+
+// TODO(bug) if constuctor call tries to output something to the LOG it will fail, because log is not initialized
+Fd Fd::stderr_(2, Mode::Reference);
+Fd Fd::stdout_(1, Mode::Reference);
+Fd Fd::stdin_(0, Mode::Reference);
+
+Fd::Fd() = default;
+
+Fd::Fd(int fd, Mode mode) : mode_(mode), fd_(fd) {
+  auto *info = get_info();
+  int old_ref_cnt = info->refcnt.load(std::memory_order_relaxed);
+  if (old_ref_cnt == 0) {
+    old_ref_cnt = info->refcnt.load(std::memory_order_acquire);
+    CHECK(old_ref_cnt == 0);
+    CHECK(mode_ == Mode::Owner) << tag("fd", fd_);
+    VLOG(fd) << "FD created [fd:" << fd_ << "]";
+
+    auto fcntl_res = fcntl(fd_, F_GETFD);
+    auto fcntl_errno = errno;
+    LOG_IF(FATAL, fcntl_res == -1) << Status::PosixError(fcntl_errno, "fcntl F_GET_FD failed");
+
+    info->refcnt.store(1, std::memory_order_relaxed);
+    CHECK(mode_ != Mode::Reference);
+    CHECK(info->observer == nullptr);
+    info->flags = 0;
+    info->observer = nullptr;
+  } else {
+    CHECK(mode_ == Mode::Reference) << tag("fd", fd_);
+    auto fcntl_res = fcntl(fd_, F_GETFD);
+    auto fcntl_errno = errno;
+    LOG_IF(FATAL, fcntl_res == -1) << Status::PosixError(fcntl_errno, "fcntl F_GET_FD failed");
+
+    CHECK(mode_ == Mode::Reference);
+    info->refcnt.fetch_add(1, std::memory_order_relaxed);
+  }
+}
+
+int Fd::move_as_native_fd() {
+  clear_info();
+  auto res = fd_;
+  fd_ = -1;
+  return res;
+}
+
+Fd::~Fd() {
+  close();
+}
+
+Fd::Fd(Fd &&other) {
+  fd_ = other.fd_;
+  mode_ = other.mode_;
+  other.fd_ = -1;
+}
+
+Fd &Fd::operator=(Fd &&other) {
+  if (this != &other) {
+    close();
+
+    fd_ = other.fd_;
+    mode_ = other.mode_;
+    other.fd_ = -1;
+  }
+  return *this;
+}
+
+Fd Fd::clone() const {
+  return Fd(fd_, Mode::Reference);
+}
+
+Fd &Fd::Stderr() {
+  return stderr_;
+}
+Fd &Fd::Stdout() {
+  return stdout_;
+}
+Fd &Fd::Stdin() {
+  return stdin_;
+}
+
+Status Fd::duplicate(const Fd &from, Fd &to) {
+  CHECK(!from.empty());
+  CHECK(!to.empty());
+  if (dup2(from.get_native_fd(), to.get_native_fd()) == -1) {
+    return OS_ERROR("dup2 failed");
+  }
+  return Status::OK();
+}
+
+bool Fd::empty() const {
+  return fd_ == -1;
+}
+
+const Fd &Fd::get_fd() const {
+  return *this;
+}
+
+Fd &Fd::get_fd() {
+  return *this;
+}
+
+int Fd::get_native_fd() const {
+  CHECK(!empty());
+  return fd_;
+}
+
+void Fd::set_observer(ObserverBase *observer) {
+  auto *info = get_info();
+  CHECK(observer == nullptr || info->observer == nullptr);
+  info->observer = observer;
+}
+
+ObserverBase *Fd::get_observer() const {
+  auto *info = get_info();
+  return info->observer;
+}
+
+void Fd::close_ref() {
+  CHECK(mode_ == Mode::Reference);
+  auto *info = get_info();
+
+  int old_ref_cnt = info->refcnt.fetch_sub(1, std::memory_order_relaxed);
+  CHECK(old_ref_cnt > 1) << tag("fd", fd_);
+  fd_ = -1;
+}
+
+void Fd::close_own() {
+  CHECK(mode_ == Mode::Owner);
+  VLOG(fd) << "FD closed [fd:" << fd_ << "]";
+
+  clear_info();
+  ::close(fd_);
+  fd_ = -1;
+}
+
+void Fd::close() {
+  if (!empty()) {
+    switch (mode_) {
+      case Mode::Reference:
+        close_ref();
+        break;
+      case Mode::Owner:
+        close_own();
+        break;
+    }
+  }
+}
+
+Fd::Info *Fd::get_info() {
+  CHECK(!empty());
+  return &fd_info_set_.get_info(fd_);
+}
+
+const Fd::Info *Fd::get_info() const {
+  CHECK(!empty());
+  return &fd_info_set_.get_info(fd_);
+}
+
+void Fd::clear_info() {
+  CHECK(!empty());
+  CHECK(mode_ != Mode::Reference);
+
+  auto *info = get_info();
+  int old_ref_cnt = info->refcnt.load(std::memory_order_relaxed);
+  CHECK(old_ref_cnt == 1);
+  info->flags = 0;
+  info->observer = nullptr;
+  info->refcnt.store(0, std::memory_order_release);
+}
+
+void Fd::update_flags_notify(Flags flags) {
+  update_flags_inner(flags, true);
+}
+
+void Fd::update_flags(Flags flags) {
+  update_flags_inner(flags, false);
+}
+
+void Fd::update_flags_inner(int32 new_flags, bool notify_flag) {
+  if (new_flags & Error) {
+    new_flags |= Error;
+    new_flags |= Close;
+  }
+  auto *info = get_info();
+  int32 &flags = info->flags;
+  int32 old_flags = flags;
+  flags |= new_flags;
+  if (new_flags & Close) {
+    // TODO: ???
+    flags &= ~Write;
+  }
+  if (flags != old_flags) {
+    VLOG(fd) << "Update flags " << tag("fd", fd_) << tag("from", format::as_binary(old_flags))
+             << tag("to", format::as_binary(flags));
+  }
+  if (flags != old_flags && notify_flag) {
+    auto observer = info->observer;
+    if (observer != nullptr) {
+      observer->notify();
+    }
+  }
+}
+
+Fd::Flags Fd::get_flags() const {
+  return get_info()->flags;
+}
+
+void Fd::clear_flags(Flags flags) {
+  get_info()->flags &= ~flags;
+}
+
+bool Fd::has_pending_error() const {
+  return (get_flags() & Fd::Flag::Error) != 0;
+}
+
+Status Fd::get_pending_error() {
+  if (!has_pending_error()) {
+    return Status::OK();
+  }
+  clear_flags(Fd::Error);
+  int error = 0;
+  socklen_t errlen = sizeof(error);
+  if (getsockopt(fd_, SOL_SOCKET, SO_ERROR, static_cast<void *>(&error), &errlen) == 0) {
+    if (error == 0) {
+      return Status::OK();
+    }
+    return Status::PosixError(error, PSLICE() << "Error on socket [fd_ = " << fd_ << "]");
+  }
+  auto status = OS_SOCKET_ERROR(PSLICE() << "Can't load error on socket [fd_ = " << fd_ << "]");
+  LOG(INFO) << "Can't load pending socket error: " << status;
+  return status;
+}
+
+Result<size_t> Fd::write_unsafe(Slice slice) {
+  int native_fd = get_native_fd();
+  auto write_res = skip_eintr([&] { return ::write(native_fd, slice.begin(), slice.size()); });
+  auto write_errno = errno;
+  if (write_res >= 0) {
+    return narrow_cast<size_t>(write_res);
+  }
+  return Status::PosixError(write_errno, PSLICE() << "Write to fd " << native_fd << " has failed");
+}
+
+Result<size_t> Fd::write(Slice slice) {
+  int native_fd = get_native_fd();
+  auto write_res = skip_eintr([&] { return ::write(native_fd, slice.begin(), slice.size()); });
+  auto write_errno = errno;
+  if (write_res >= 0) {
+    return narrow_cast<size_t>(write_res);
+  }
+
+  if (write_errno == EAGAIN
+#if EAGAIN != EWOULDBLOCK
+      || write_errno == EWOULDBLOCK
+#endif
+  ) {
+    clear_flags(Write);
+    return 0;
+  }
+
+  auto error = Status::PosixError(write_errno, PSLICE() << "Write to fd " << native_fd << " has failed");
+  switch (write_errno) {
+    case EBADF:
+    case ENXIO:
+    case EFAULT:
+    case EINVAL:
+      LOG(FATAL) << error;
+      UNREACHABLE();
+    default:
+      LOG(WARNING) << error;
+    // fallthrough
+    case ECONNRESET:
+    case EDQUOT:
+    case EFBIG:
+    case EIO:
+    case ENETDOWN:
+    case ENETUNREACH:
+    case ENOSPC:
+    case EPIPE:
+      clear_flags(Write);
+      update_flags(Close);
+      return std::move(error);
+  }
+}
+
+Result<size_t> Fd::read(MutableSlice slice) {
+  int native_fd = get_native_fd();
+  CHECK(slice.size() > 0);
+  auto read_res = skip_eintr([&] { return ::read(native_fd, slice.begin(), slice.size()); });
+  auto read_errno = errno;
+  if (read_res >= 0) {
+    if (read_res == 0) {
+      errno = 0;
+      clear_flags(Read);
+      update_flags(Close);
+    }
+    return narrow_cast<size_t>(read_res);
+  }
+  if (read_errno == EAGAIN
+#if EAGAIN != EWOULDBLOCK
+      || read_errno == EWOULDBLOCK
+#endif
+  ) {
+    clear_flags(Read);
+    return 0;
+  }
+  auto error = Status::PosixError(read_errno, PSLICE() << "Read from fd " << native_fd << " has failed");
+  switch (read_errno) {
+    case EISDIR:
+    case EBADF:
+    case ENXIO:
+    case EFAULT:
+    case EINVAL:
+    case ENOTCONN:
+      LOG(FATAL) << error;
+      UNREACHABLE();
+    default:
+      LOG(WARNING) << error;
+    // fallthrough
+    case EIO:
+    case ENOBUFS:
+    case ENOMEM:
+    case ECONNRESET:
+    case ETIMEDOUT:
+      clear_flags(Read);
+      update_flags(Close);
+      return std::move(error);
+  }
+}
+
+Status Fd::set_is_blocking(bool is_blocking) {
+  auto old_flags = fcntl(fd_, F_GETFL);
+  if (old_flags == -1) {
+    return OS_SOCKET_ERROR("Failed to get socket flags");
+  }
+  auto new_flags = is_blocking ? old_flags & ~O_NONBLOCK : old_flags | O_NONBLOCK;
+  if (new_flags != old_flags && fcntl(fd_, F_SETFL, new_flags) == -1) {
+    return OS_SOCKET_ERROR("Failed to set socket flags");
+  }
+
+  return Status::OK();
+}
+
+#endif
+
+#if TD_PORT_WINDOWS
+
+class Fd::FdImpl {
+ public:
+  FdImpl(Fd::Type type, HANDLE handle)
+      : type_(type), handle_(handle), async_mode_(type_ == Fd::Type::EventFd || type_ == Fd::Type::StdinFileFd) {
+    init();
+  }
+  FdImpl(Fd::Type type, SOCKET socket, int socket_family)
+      : type_(type), socket_(socket), socket_family_(socket_family), async_mode_(true) {
+    init();
+  }
+
+  FdImpl(const FdImpl &) = delete;
+  FdImpl &operator=(const FdImpl &) = delete;
+  FdImpl(FdImpl &&) = delete;
+  FdImpl &operator=(FdImpl &&) = delete;
+
+  ~FdImpl() {
+    close();
+  }
+  void set_observer(ObserverBase *observer) {
+    observer_ = observer;
+  }
+  ObserverBase *get_observer() const {
+    return observer_;
+  }
+
+  void update_flags_notify(Fd::Flags flags) {
+    update_flags_inner(flags, true);
+  }
+
+  void update_flags(Fd::Flags flags) {
+    update_flags_inner(flags, false);
+  }
+
+  void update_flags_inner(int32 new_flags, bool notify_flag) {
+    if (new_flags & Fd::Error) {
+      new_flags |= Fd::Error;
+      new_flags |= Fd::Close;
+    }
+    int32 old_flags = flags_;
+    flags_ |= new_flags;
+    if (new_flags & Fd::Close) {
+      // TODO: ???
+      flags_ &= ~Fd::Write;
+      internal_flags_ &= ~Fd::Write;
+    }
+    if (flags_ != old_flags) {
+      VLOG(fd) << "Update flags " << tag("fd", get_io_handle()) << tag("from", format::as_binary(old_flags))
+               << tag("to", format::as_binary(flags_));
+    }
+    if (flags_ != old_flags && notify_flag) {
+      auto observer = get_observer();
+      if (observer != nullptr) {
+        observer->notify();
+      }
+    }
+  }
+
+  int32 get_flags() const {
+    return flags_;
+  }
+
+  void clear_flags(Fd::Flags mask) {
+    flags_ &= ~mask;
+  }
+
+  Status get_pending_error() {
+    if (!has_pending_error()) {
+      return Status::OK();
+    }
+    clear_flags(Fd::Error);
+    return std::move(pending_error_);
+  }
+  bool has_pending_error() const {
+    return (get_flags() & Fd::Flag::Error) != 0;
+  }
+
+  HANDLE get_read_event() {
+    if (type() == Fd::Type::StdinFileFd) {
+      return get_io_handle();
+    }
+    return read_event_;
+  }
+  void on_read_event() {
+    if (type_ == Fd::Type::StdinFileFd) {
+      return try_read_stdin();
+    }
+    ResetEvent(read_event_);
+    if (type_ == Fd::Type::EventFd) {
+      return update_flags_notify(Fd::Flag::Read);
+    }
+    if (type_ == Fd::Type::SocketFd && !connected_) {
+      on_connect_ready();
+    } else {
+      if (!async_read_flag_) {
+        return;
+      }
+
+      if (type_ == Fd::Type::ServerSocketFd) {
+        on_accept_ready();
+      } else {
+        on_read_ready();
+      }
+    }
+    loop();
+  }
+  HANDLE get_write_event() {
+    return write_event_;
+  }
+  void on_write_event() {
+    CHECK(async_write_flag_);
+    ResetEvent(write_event_);
+    on_write_ready();
+    loop();
+  }
+
+  SOCKET get_native_socket() const {
+    return socket_;
+  }
+
+  HANDLE get_io_handle() const {
+    CHECK(!empty());
+    if (type() == Fd::Type::FileFd || type() == Fd::Type::StdinFileFd) {
+      return handle_;
+    }
+    return reinterpret_cast<HANDLE>(socket_);
+  }
+
+  Result<size_t> write(Slice slice) TD_WARN_UNUSED_RESULT {
+    if (async_mode_) {
+      return write_async(slice);
+    } else {
+      return write_sync(slice);
+    }
+  }
+
+  Result<size_t> read(MutableSlice slice) TD_WARN_UNUSED_RESULT {
+    if (async_mode_) {
+      return read_async(slice);
+    } else {
+      return read_sync(slice);
+    }
+  }
+
+  Result<size_t> write_async(Slice slice) TD_WARN_UNUSED_RESULT {
+    CHECK(async_mode_);
+    output_writer_.append(slice);
+    output_reader_.sync_with_writer();
+    loop();
+    return slice.size();
+  }
+  Result<size_t> write_sync(Slice slice) TD_WARN_UNUSED_RESULT {
+    CHECK(!async_mode_);
+    DWORD bytes_written = 0;
+    auto res = WriteFile(get_io_handle(), slice.data(), narrow_cast<DWORD>(slice.size()), &bytes_written, nullptr);
+    if (!res) {
+      return OS_ERROR("Failed to write_sync");
+    }
+    return bytes_written;
+  }
+  Result<size_t> read_async(MutableSlice slice) TD_WARN_UNUSED_RESULT {
+    CHECK(async_mode_);
+    auto res = input_reader_.advance(min(slice.size(), input_reader_.size()), slice);
+    if (res == 0) {
+      clear_flags(Fd::Flag::Read);
+    }
+    return res;
+  }
+  Result<size_t> read_sync(MutableSlice slice) TD_WARN_UNUSED_RESULT {
+    CHECK(!async_mode_);
+    DWORD bytes_read = 0;
+    auto res = ReadFile(get_io_handle(), slice.data(), narrow_cast<DWORD>(slice.size()), &bytes_read, nullptr);
+    if (!res) {
+      return OS_ERROR("Failed to read_sync");
+    }
+    if (bytes_read == 0) {
+      clear_flags(Fd::Flag::Read);
+    }
+    return bytes_read;
+  }
+
+  // for ServerSocket
+  Result<Fd> accept() {
+    if (accepted_.empty()) {
+      clear_flags(Fd::Flag::Read);
+      return Status::Error(-1, "Operation would block");
+    }
+    auto res = std::move(accepted_.back());
+    accepted_.pop_back();
+    return std::move(res);
+  }
+
+  void connect(const IPAddress &addr) {
+    CHECK(!connected_);
+    CHECK(type_ == Fd::Type::SocketFd);
+    DWORD bytes_read;
+    std::memset(&read_overlapped_, 0, sizeof(read_overlapped_));
+    read_overlapped_.hEvent = read_event_;
+    LPFN_CONNECTEX ConnectExPtr = nullptr;
+    GUID guid = WSAID_CONNECTEX;
+    DWORD numBytes;
+    int error = ::WSAIoctl(socket_, SIO_GET_EXTENSION_FUNCTION_POINTER, static_cast<void *>(&guid), sizeof(guid),
+                           static_cast<void *>(&ConnectExPtr), sizeof(ConnectExPtr), &numBytes, nullptr, nullptr);
+    if (error) {
+      return on_error(OS_SOCKET_ERROR("WSAIoctl failed"), Fd::Flag::Read);
+    }
+    auto status = ConnectExPtr(socket_, addr.get_sockaddr(), narrow_cast<int>(addr.get_sockaddr_len()), nullptr, 0,
+                               &bytes_read, &read_overlapped_);
+    if (status != 0) {
+      ResetEvent(read_event_);
+      connected_ = true;
+      update_flags_notify(Fd::Flag::Read);
+      return;
+    }
+
+    auto last_error = GetLastError();
+    if (last_error == ERROR_IO_PENDING) {
+      return;
+    }
+    on_error(OS_SOCKET_ERROR("ConnectEx failed"), Fd::Flag::Read);
+  }
+
+  // for EventFd
+  void release() {
+    CHECK(type_ == Fd::Type::EventFd);
+    SetEvent(read_event_);
+  }
+
+  void acquire() {
+    CHECK(type_ == Fd::Type::EventFd);
+    ResetEvent(read_event_);
+    clear_flags(Fd::Flag::Read);
+  }
+
+  // TODO: interface for BufferedFd optimization.
+
+  bool empty() const {
+    return type() == Fd::Type::Empty;
+  }
+  void close() {
+    if (empty()) {
+      return;
+    }
+    switch (type()) {
+      case Fd::Type::StdinFileFd:
+      case Fd::Type::FileFd: {
+        if (!CloseHandle(handle_)) {
+          auto error = OS_ERROR("Failed to close file");
+          LOG(ERROR) << error;
+        }
+        handle_ = INVALID_HANDLE_VALUE;
+        break;
+      }
+      case Fd::Type::ServerSocketFd:
+      case Fd::Type::SocketFd: {
+        if (closesocket(socket_) != 0) {
+          auto error = OS_SOCKET_ERROR("Failed to close socket");
+          LOG(ERROR) << error;
+        }
+        socket_ = INVALID_SOCKET;
+        break;
+      }
+      case Fd::Type::EventFd:
+        break;
+      default:
+        UNREACHABLE();
+    }
+
+    if (read_event_ != INVALID_HANDLE_VALUE) {
+      if (!CloseHandle(read_event_)) {
+        auto error = OS_ERROR("Failed to close event");
+        LOG(ERROR) << error;
+      }
+      read_event_ = INVALID_HANDLE_VALUE;
+    }
+    if (write_event_ != INVALID_HANDLE_VALUE) {
+      if (!CloseHandle(write_event_)) {
+        auto error = OS_ERROR("Failed to close event");
+        LOG(ERROR) << error;
+      }
+      write_event_ = INVALID_HANDLE_VALUE;
+    }
+
+    type_ = Fd::Type::Empty;
+  }
+
+ private:
+  Fd::Type type_;
+  HANDLE handle_ = INVALID_HANDLE_VALUE;
+  SOCKET socket_ = INVALID_SOCKET;
+
+  int socket_family_ = 0;
+
+  bool async_mode_ = false;
+
+  ObserverBase *observer_ = nullptr;
+  Fd::Flags flags_ = Fd::Flag::Write;
+  Status pending_error_;
+  Fd::Flags internal_flags_ = Fd::Flag::Write | Fd::Flag::Read;
+
+  HANDLE read_event_ = INVALID_HANDLE_VALUE;  // used by WineventPoll
+  bool async_read_flag_ = false;              // do we have pending read?
+  OVERLAPPED read_overlapped_;
+  ChainBufferWriter input_writer_;
+  ChainBufferReader input_reader_ = input_writer_.extract_reader();
+
+  bool connected_ = false;
+
+  std::vector<Fd> accepted_;
+  SOCKET accept_socket_ = INVALID_SOCKET;
+  static constexpr size_t MAX_ADDR_SIZE = sizeof(sockaddr_in6) + 16;
+  char addr_buf_[MAX_ADDR_SIZE * 2];
+
+  HANDLE write_event_ = INVALID_HANDLE_VALUE;  // used by WineventPoll
+  bool async_write_flag_ = false;              // do we have pending write?
+  OVERLAPPED write_overlapped_;
+  ChainBufferWriter output_writer_;
+  ChainBufferReader output_reader_ = output_writer_.extract_reader();
+
+  void init() {
+    if (async_mode_) {
+      if (type_ != Fd::Type::EventFd) {
+        write_event_ = CreateEventW(nullptr, true, false, nullptr);
+      }
+      read_event_ = CreateEventW(nullptr, true, false, nullptr);
+      loop();
+    }
+  }
+
+  Fd::Type type() const {
+    return type_;
+  }
+
+  void on_error(Status error, Fd::Flag flag) {
+    VLOG(fd) << tag("fd", get_io_handle()) << error;
+    pending_error_ = std::move(error);
+    internal_flags_ &= ~flag;
+    update_flags_notify(Fd::Flag::Error);
+  }
+  void on_eof() {
+    internal_flags_ &= ~Fd::Flag::Read;
+    update_flags_notify(Fd::Flag::Close);
+  }
+
+  void on_read_ready() {
+    async_read_flag_ = false;
+    DWORD bytes_read;
+    auto status = GetOverlappedResult(get_io_handle(), &read_overlapped_, &bytes_read, false);
+    if (status == 0) {
+      return on_error(OS_ERROR("ReadFile failed"), Fd::Flag::Read);
+    }
+
+    VLOG(fd) << "Read " << tag("fd", get_io_handle()) << tag("size", bytes_read);
+    if (bytes_read == 0) {  // eof
+      return on_eof();
+    }
+    input_writer_.confirm_append(bytes_read);
+    input_reader_.sync_with_writer();
+    update_flags_notify(Fd::Flag::Read);
+  }
+  void on_write_ready() {
+    async_write_flag_ = false;
+    DWORD bytes_written;
+    auto status = GetOverlappedResult(get_io_handle(), &write_overlapped_, &bytes_written, false);
+    if (status == 0) {
+      return on_error(OS_ERROR("WriteFile failed"), Fd::Flag::Write);
+    }
+    if (bytes_written != 0) {
+      VLOG(fd) << "Write " << tag("fd", get_io_handle()) << tag("size", bytes_written);
+      output_reader_.confirm_read(bytes_written);
+      update_flags_notify(Fd::Flag::Write);
+    }
+  }
+
+  void on_accept_ready() {
+    async_read_flag_ = false;
+    DWORD bytes_read;
+    auto status = GetOverlappedResult(get_io_handle(), &read_overlapped_, &bytes_read, false);
+    if (status == 0) {
+      return on_error(OS_ERROR("AcceptEx failed"), Fd::Flag::Write);
+    }
+    accepted_.push_back(Fd::create_socket_fd(accept_socket_));
+    accept_socket_ = INVALID_SOCKET;
+    update_flags_notify(Fd::Flag::Read);
+  }
+
+  void on_connect_ready() {
+    async_read_flag_ = false;
+    DWORD bytes_read;
+    VLOG(fd) << "on_connect_ready";
+    auto status = GetOverlappedResult(get_io_handle(), &read_overlapped_, &bytes_read, false);
+    if (status == 0) {
+      return on_error(OS_ERROR("ConnectEx failed"), Fd::Flag::Write);
+    }
+    connected_ = true;
+    VLOG(fd) << "connected = true";
+  }
+
+  void try_read_stdin() {
+  }
+  void try_start_read() {
+    auto dest = input_writer_.prepare_append();
+    DWORD bytes_read;
+    std::memset(&read_overlapped_, 0, sizeof(read_overlapped_));
+    read_overlapped_.hEvent = read_event_;
+    VLOG(fd) << "try_read..";
+    auto status =
+        ReadFile(get_io_handle(), dest.data(), narrow_cast<DWORD>(dest.size()), &bytes_read, &read_overlapped_);
+    if (status != 0) {  // ok
+      ResetEvent(read_event_);
+      VLOG(fd) << "Read " << tag("fd", get_io_handle()) << tag("size", bytes_read);
+      if (bytes_read == 0) {  // eof
+        return on_eof();
+      }
+      input_writer_.confirm_append(bytes_read);
+      input_reader_.sync_with_writer();
+      update_flags_notify(Fd::Flag::Read);
+      return;
+    }
+    auto last_error = GetLastError();
+    if (last_error == ERROR_IO_PENDING) {
+      async_read_flag_ = true;
+      return;
+    }
+    on_error(OS_ERROR("ReadFile failed"), Fd::Flag::Read);
+  }
+
+  void try_start_write() {
+    auto dest = output_reader_.prepare_read();
+    DWORD bytes_written;
+    std::memset(&write_overlapped_, 0, sizeof(write_overlapped_));
+    write_overlapped_.hEvent = write_event_;
+    VLOG(fd) << "try_start_write";
+    auto status =
+        WriteFile(get_io_handle(), dest.data(), narrow_cast<DWORD>(dest.size()), &bytes_written, &write_overlapped_);
+    if (status != 0) {  // ok
+      VLOG(fd) << "Write " << tag("fd", get_io_handle()) << tag("size", bytes_written);
+      ResetEvent(write_event_);
+      output_reader_.confirm_read(bytes_written);
+      update_flags_notify(Fd::Flag::Write);
+      return;
+    }
+    auto last_error = GetLastError();
+    if (last_error == ERROR_IO_PENDING) {
+      VLOG(fd) << "try_start_write: ERROR_IO_PENDING";
+      async_write_flag_ = true;
+      return;
+    }
+    CHECK(WaitForSingleObject(write_event_, 0) != WAIT_OBJECT_0);
+    on_error(OS_ERROR("WriteFile failed"), Fd::Flag::Write);
+  }
+
+  void try_start_accept() {
+    if (async_read_flag_ == true) {
+      return;
+    }
+    accept_socket_ = socket(socket_family_, SOCK_STREAM, 0);
+    DWORD bytes_read;
+    std::memset(&read_overlapped_, 0, sizeof(read_overlapped_));
+    read_overlapped_.hEvent = read_event_;
+    auto status =
+        AcceptEx(socket_, accept_socket_, addr_buf_, 0, MAX_ADDR_SIZE, MAX_ADDR_SIZE, &bytes_read, &read_overlapped_);
+    if (status != 0) {
+      ResetEvent(read_event_);
+      accepted_.push_back(Fd::create_socket_fd(accept_socket_));
+      accept_socket_ = INVALID_SOCKET;
+      update_flags_notify(Fd::Flag::Read);
+      return;
+    }
+
+    auto last_error = GetLastError();
+    if (last_error == ERROR_IO_PENDING) {
+      async_read_flag_ = true;
+      return;
+    }
+    on_error(OS_SOCKET_ERROR("AcceptExFailed"), Fd::Flag::Read);
+  }
+
+  void loop() {
+    CHECK(async_mode_);
+
+    if (type_ == Fd::Type::EventFd) {
+      return;
+    }
+    if (type_ == Fd::Type::ServerSocketFd) {
+      while (async_read_flag_ == false && (internal_flags_ & Fd::Flag::Read) != 0) {
+        // read always
+        try_start_accept();
+      }
+      return;
+    }
+    if (!connected_) {
+      return;
+    }
+    while (async_read_flag_ == false && (internal_flags_ & Fd::Flag::Read) != 0) {
+      // read always
+      try_start_read();
+    }
+    VLOG(fd) << (async_write_flag_ == false) << " " << output_reader_.size() << " "
+             << ((internal_flags_ & Fd::Flag::Write) != 0);
+    while (async_write_flag_ == false && output_reader_.size() && (internal_flags_ & Fd::Flag::Write) != 0) {
+      // write if we have data to write
+      try_start_write();
+    }
+  }
+};
+
+Fd::Fd() = default;
+
+Fd::Fd(Fd &&other) = default;
+
+Fd &Fd::operator=(Fd &&other) = default;
+
+Fd::~Fd() = default;
+
+Fd Fd::create_file_fd(HANDLE handle) {
+  return Fd(Fd::Type::FileFd, Fd::Mode::Owner, handle);
+}
+
+Fd Fd::create_socket_fd(SOCKET sock) {
+  return Fd(Fd::Type::SocketFd, Fd::Mode::Owner, sock, AF_UNSPEC);
+}
+
+Fd Fd::create_server_socket_fd(SOCKET sock, int socket_family) {
+  return Fd(Fd::Type::ServerSocketFd, Fd::Mode::Owner, sock, socket_family);
+}
+
+Fd Fd::create_event_fd() {
+  return Fd(Fd::Type::EventFd, Fd::Mode::Owner, INVALID_HANDLE_VALUE);
+}
+
+const Fd &Fd::get_fd() const {
+  return *this;
+}
+
+Fd &Fd::get_fd() {
+  return *this;
+}
+
+Result<size_t> Fd::read(MutableSlice slice) {
+  return impl_->read(slice);
+}
+
+Result<size_t> Fd::write(Slice slice) {
+  CHECK(!empty());
+  return impl_->write(slice);
+}
+
+bool Fd::empty() const {
+  return !impl_;
+}
+
+void Fd::close() {
+  impl_.reset();
+}
+
+Result<Fd> Fd::accept() {
+  return impl_->accept();
+}
+void Fd::connect(const IPAddress &addr) {
+  return impl_->connect(addr);
+}
+
+Fd Fd::clone() const {
+  return Fd(impl_);
+}
+
+uint64 Fd::get_key() const {
+  return reinterpret_cast<uint64>(impl_.get());
+}
+
+void Fd::set_observer(ObserverBase *observer) {
+  return impl_->set_observer(observer);
+}
+ObserverBase *Fd::get_observer() const {
+  return impl_->get_observer();
+}
+
+Fd::Flags Fd::get_flags() const {
+  return impl_->get_flags();
+}
+void Fd::update_flags(Flags flags) {
+  impl_->update_flags(flags);
+}
+
+void Fd::on_read_event() {
+  impl_->on_read_event();
+}
+void Fd::on_write_event() {
+  impl_->on_write_event();
+}
+
+bool Fd::has_pending_error() const {
+  return impl_->has_pending_error();
+}
+Status Fd::get_pending_error() {
+  return impl_->get_pending_error();
+}
+
+HANDLE Fd::get_read_event() {
+  return impl_->get_read_event();
+}
+HANDLE Fd::get_write_event() {
+  return impl_->get_write_event();
+}
+
+SOCKET Fd::get_native_socket() const {
+  return impl_->get_native_socket();
+}
+
+HANDLE Fd::get_io_handle() const {
+  return impl_->get_io_handle();
+}
+
+#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP | WINAPI_PARTITION_SYSTEM)
+Fd &Fd::Stderr() {
+  static auto handle = GetStdHandle(STD_ERROR_HANDLE);
+  LOG_IF(FATAL, handle == INVALID_HANDLE_VALUE) << "Failed to get stderr";
+  static auto fd = Fd(Fd::Type::FileFd, Fd::Mode::Reference, handle);
+  return fd;
+}
+Fd &Fd::Stdin() {
+  static auto handle = GetStdHandle(STD_INPUT_HANDLE);
+  LOG_IF(FATAL, handle == INVALID_HANDLE_VALUE) << "Failed to get stdin";
+  static auto fd = Fd(Fd::Type::FileFd, Fd::Mode::Reference, handle);
+  return fd;
+}
+Fd &Fd::Stdout() {
+  static auto handle = GetStdHandle(STD_OUTPUT_HANDLE);
+  LOG_IF(FATAL, handle == INVALID_HANDLE_VALUE) << "Failed to get stdout";
+  static auto fd = Fd(Fd::Type::FileFd, Fd::Mode::Reference, handle);
+  return fd;
+}
+#else
+Fd &Fd::Stderr() {
+  static Fd result;
+  result = Fd();
+  return result;
+}
+Fd &Fd::Stdin() {
+  static Fd result;
+  result = Fd();
+  return result;
+}
+Fd &Fd::Stdout() {
+  static Fd result;
+  result = Fd();
+  return result;
+}
+#endif
+
+Status Fd::duplicate(const Fd &from, Fd &to) {
+  return Status::Error("Not supported");
+}
+
+Status Fd::set_is_blocking(bool is_blocking) {
+  return detail::set_native_socket_is_blocking(get_native_socket(), is_blocking);
+}
+
+Fd::Fd(Type type, Mode mode, HANDLE handle) : mode_(mode), impl_(std::make_shared<FdImpl>(type, handle)) {
+}
+
+Fd::Fd(Type type, Mode mode, SOCKET sock, int socket_family)
+    : mode_(mode), impl_(std::make_shared<FdImpl>(type, sock, socket_family)) {
+}
+
+Fd::Fd(std::shared_ptr<FdImpl> impl) : mode_(Mode::Reference), impl_(std::move(impl)) {
+}
+
+void Fd::acquire() {
+  return impl_->acquire();
+}
+
+void Fd::release() {
+  return impl_->release();
+}
+
+class InitWSA {
+ public:
+  InitWSA() {
+    /* Use the MAKEWORD(lowbyte, highbyte) macro declared in Windef.h */
+    WORD wVersionRequested = MAKEWORD(2, 2);
+    WSADATA wsaData;
+    if (WSAStartup(wVersionRequested, &wsaData) != 0) {
+      auto error = OS_SOCKET_ERROR("Failed to init WSA");
+      LOG(FATAL) << error;
+    }
+  }
+};
+
+static InitWSA init_wsa;
+
+#endif
+
+namespace detail {
+#if TD_PORT_POSIX
+Status set_native_socket_is_blocking(int fd, bool is_blocking) {
+  if (fcntl(fd, F_SETFL, is_blocking ? 0 : O_NONBLOCK) == -1) {
+#elif TD_PORT_WINDOWS
+Status set_native_socket_is_blocking(SOCKET fd, bool is_blocking) {
+  u_long mode = is_blocking;
+  if (ioctlsocket(fd, FIONBIO, &mode) != 0) {
+#endif
+    return OS_SOCKET_ERROR("Failed to change socket flags");
+  }
+  return Status::OK();
+}
+}  // namespace detail
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/Fd.h b/libs/tdlib/td/tdutils/td/utils/port/Fd.h
new file mode 100644
index 0000000000..5ce9b6cedc
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/Fd.h
@@ -0,0 +1,226 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#if TD_PORT_WINDOWS
+#include "td/utils/port/IPAddress.h"
+
+#include <memory>
+#endif
+
+#if TD_PORT_POSIX
+#include <errno.h>
+
+#include <atomic>
+#include <type_traits>
+#endif
+
+namespace td {
+
+class ObserverBase;
+
+#if TD_PORT_WINDOWS
+namespace detail {
+class EventFdWindows;
+}  // namespace detail
+#endif
+
+class Fd {
+ public:
+  // TODO: Close may be not enough
+  // Sometimes descriptor is half-closed.
+
+  enum Flag : int32 {
+    Write = 0x001,
+    Read = 0x002,
+    Close = 0x004,
+    Error = 0x008,
+    All = Write | Read | Close | Error,
+    None = 0
+  };
+  using Flags = int32;
+  enum class Mode { Reference, Owner };
+
+  Fd();
+  Fd(const Fd &) = delete;
+  Fd &operator=(const Fd &) = delete;
+  Fd(Fd &&other);
+  Fd &operator=(Fd &&other);
+  ~Fd();
+
+#if TD_PORT_POSIX
+  Fd(int fd, Mode mode);
+#endif
+#if TD_PORT_WINDOWS
+  static Fd create_file_fd(HANDLE handle);
+
+  static Fd create_socket_fd(SOCKET sock);
+
+  static Fd create_server_socket_fd(SOCKET sock, int socket_family);
+
+  static Fd create_event_fd();
+#endif
+
+  Fd clone() const;
+
+  static Fd &Stderr();
+  static Fd &Stdout();
+  static Fd &Stdin();
+
+  static Status duplicate(const Fd &from, Fd &to);
+
+  bool empty() const;
+
+  const Fd &get_fd() const;
+  Fd &get_fd();
+
+  void set_observer(ObserverBase *observer);
+  ObserverBase *get_observer() const;
+
+  void close();
+
+  void update_flags(Flags flags);
+
+  Flags get_flags() const;
+
+  bool has_pending_error() const;
+  Status get_pending_error() TD_WARN_UNUSED_RESULT;
+
+  Result<size_t> write(Slice slice) TD_WARN_UNUSED_RESULT;
+  Result<size_t> read(MutableSlice slice) TD_WARN_UNUSED_RESULT;
+
+  Status set_is_blocking(bool is_blocking);
+
+#if TD_PORT_POSIX
+  void update_flags_notify(Flags flags);
+  void clear_flags(Flags flags);
+
+  Result<size_t> write_unsafe(Slice slice) TD_WARN_UNUSED_RESULT;
+
+  int get_native_fd() const;
+  int move_as_native_fd();
+#endif
+
+#if TD_PORT_WINDOWS
+  Result<Fd> accept() TD_WARN_UNUSED_RESULT;
+  void connect(const IPAddress &addr);
+
+  uint64 get_key() const;
+
+  HANDLE get_read_event();
+  HANDLE get_write_event();
+  void on_read_event();
+  void on_write_event();
+
+  SOCKET get_native_socket() const;
+  HANDLE get_io_handle() const;
+#endif
+
+ private:
+  Mode mode_ = Mode::Owner;
+
+#if TD_PORT_POSIX
+  struct Info {
+    std::atomic<int> refcnt;
+    int32 flags;
+    ObserverBase *observer;
+  };
+  struct InfoSet {
+    InfoSet();
+    Info &get_info(int32 id);
+
+   private:
+    static constexpr int MAX_FD = 1 << 18;
+    Info fd_array_[MAX_FD];
+  };
+  static InfoSet fd_info_set_;
+
+  static Fd stderr_;
+  static Fd stdout_;
+  static Fd stdin_;
+
+  void update_flags_inner(int32 new_flags, bool notify_flag);
+  Info *get_info();
+  const Info *get_info() const;
+  void clear_info();
+
+  void close_ref();
+  void close_own();
+
+  int fd_ = -1;
+#endif
+#if TD_PORT_WINDOWS
+  class FdImpl;
+
+  enum class Type { Empty, EventFd, FileFd, StdinFileFd, SocketFd, ServerSocketFd };
+
+  Fd(Type type, Mode mode, HANDLE handle);
+  Fd(Type type, Mode mode, SOCKET sock, int socket_family);
+  explicit Fd(std::shared_ptr<FdImpl> impl);
+
+  friend class detail::EventFdWindows;  // for release and acquire
+
+  void acquire();
+  void release();
+
+  std::shared_ptr<FdImpl> impl_;
+#endif
+};
+
+#if TD_PORT_POSIX
+template <class F>
+auto skip_eintr(F &&f) {
+  decltype(f()) res;
+  static_assert(std::is_integral<decltype(res)>::value, "integral type expected");
+  do {
+    errno = 0;  // just in case
+    res = f();
+  } while (res < 0 && errno == EINTR);
+  return res;
+}
+template <class F>
+auto skip_eintr_cstr(F &&f) {
+  char *res;
+  do {
+    errno = 0;  // just in case
+    res = f();
+  } while (res == nullptr && errno == EINTR);
+  return res;
+}
+#endif
+
+template <class FdT>
+bool can_read(const FdT &fd) {
+  return (fd.get_flags() & Fd::Read) != 0;
+}
+
+template <class FdT>
+bool can_write(const FdT &fd) {
+  return (fd.get_flags() & Fd::Write) != 0;
+}
+
+template <class FdT>
+bool can_close(const FdT &fd) {
+  return (fd.get_flags() & Fd::Close) != 0;
+}
+
+namespace detail {
+#if TD_PORT_POSIX
+Status set_native_socket_is_blocking(int fd, bool is_blocking);
+#endif
+#if TD_PORT_WINDOWS
+Status set_native_socket_is_blocking(SOCKET fd, bool is_blocking);
+#endif
+}  // namespace detail
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/FileFd.cpp b/libs/tdlib/td/tdutils/td/utils/port/FileFd.cpp
new file mode 100644
index 0000000000..17a2727f64
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/FileFd.cpp
@@ -0,0 +1,481 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/FileFd.h"
+
+#if TD_PORT_WINDOWS
+#include "td/utils/misc.h"  // for narrow_cast
+
+#include "td/utils/port/Stat.h"
+#include "td/utils/port/wstring_convert.h"
+#endif
+
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/sleep.h"
+#include "td/utils/StringBuilder.h"
+
+#include <cstring>
+
+#if TD_PORT_POSIX
+#include <fcntl.h>
+#include <sys/file.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <unistd.h>
+#endif
+
+namespace td {
+
+namespace {
+
+struct PrintFlags {
+  int32 flags;
+};
+
+StringBuilder &operator<<(StringBuilder &sb, const PrintFlags &print_flags) {
+  auto flags = print_flags.flags;
+  if (flags &
+      ~(FileFd::Write | FileFd::Read | FileFd::Truncate | FileFd::Create | FileFd::Append | FileFd::CreateNew)) {
+    return sb << "opened with invalid flags " << flags;
+  }
+
+  if (flags & FileFd::Create) {
+    sb << "opened/created ";
+  } else if (flags & FileFd::CreateNew) {
+    sb << "created ";
+  } else {
+    sb << "opened ";
+  }
+
+  if ((flags & FileFd::Write) && (flags & FileFd::Read)) {
+    if (flags & FileFd::Append) {
+      sb << "for reading and appending";
+    } else {
+      sb << "for reading and writing";
+    }
+  } else if (flags & FileFd::Write) {
+    if (flags & FileFd::Append) {
+      sb << "for appending";
+    } else {
+      sb << "for writing";
+    }
+  } else if (flags & FileFd::Read) {
+    sb << "for reading";
+  } else {
+    sb << "for nothing";
+  }
+
+  if (flags & FileFd::Truncate) {
+    sb << " with truncation";
+  }
+  return sb;
+}
+
+}  // namespace
+
+const Fd &FileFd::get_fd() const {
+  return fd_;
+}
+
+Fd &FileFd::get_fd() {
+  return fd_;
+}
+
+Result<FileFd> FileFd::open(CSlice filepath, int32 flags, int32 mode) {
+  if (flags & ~(Write | Read | Truncate | Create | Append | CreateNew)) {
+    return Status::Error(PSLICE() << "File \"" << filepath << "\" has failed to be " << PrintFlags{flags});
+  }
+
+  if ((flags & (Write | Read)) == 0) {
+    return Status::Error(PSLICE() << "File \"" << filepath << "\" can't be " << PrintFlags{flags});
+  }
+
+#if TD_PORT_POSIX
+  int native_flags = 0;
+
+  if ((flags & Write) && (flags & Read)) {
+    native_flags |= O_RDWR;
+  } else if (flags & Write) {
+    native_flags |= O_WRONLY;
+  } else {
+    CHECK(flags & Read);
+    native_flags |= O_RDONLY;
+  }
+
+  if (flags & Truncate) {
+    native_flags |= O_TRUNC;
+  }
+
+  if (flags & Create) {
+    native_flags |= O_CREAT;
+  } else if (flags & CreateNew) {
+    native_flags |= O_CREAT;
+    native_flags |= O_EXCL;
+  }
+
+  if (flags & Append) {
+    native_flags |= O_APPEND;
+  }
+
+  int native_fd = skip_eintr([&] { return ::open(filepath.c_str(), native_flags, static_cast<mode_t>(mode)); });
+  if (native_fd < 0) {
+    return OS_ERROR(PSLICE() << "File \"" << filepath << "\" can't be " << PrintFlags{flags});
+  }
+
+  FileFd result;
+  result.fd_ = Fd(native_fd, Fd::Mode::Owner);
+#elif TD_PORT_WINDOWS
+  // TODO: support modes
+  auto r_filepath = to_wstring(filepath);
+  if (r_filepath.is_error()) {
+    return Status::Error(PSLICE() << "Failed to convert file path \" << filepath << \" to UTF-16");
+  }
+  auto w_filepath = r_filepath.move_as_ok();
+  DWORD desired_access = 0;
+  if ((flags & Write) && (flags & Read)) {
+    desired_access |= GENERIC_READ | GENERIC_WRITE;
+  } else if (flags & Write) {
+    desired_access |= GENERIC_WRITE;
+  } else {
+    CHECK(flags & Read);
+    desired_access |= GENERIC_READ;
+  }
+
+  // TODO: share mode
+  DWORD share_mode = FILE_SHARE_READ | FILE_SHARE_DELETE | FILE_SHARE_WRITE;
+
+  DWORD creation_disposition = 0;
+  if (flags & Create) {
+    if (flags & Truncate) {
+      creation_disposition = CREATE_ALWAYS;
+    } else {
+      creation_disposition = OPEN_ALWAYS;
+    }
+  } else if (flags & CreateNew) {
+    creation_disposition = CREATE_NEW;
+  } else {
+    if (flags & Truncate) {
+      creation_disposition = TRUNCATE_EXISTING;
+    } else {
+      creation_disposition = OPEN_EXISTING;
+    }
+  }
+
+#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP | WINAPI_PARTITION_SYSTEM)
+  auto handle = CreateFile(w_filepath.c_str(), desired_access, share_mode, nullptr, creation_disposition, 0, nullptr);
+#else
+  auto handle = CreateFile2(w_filepath.c_str(), desired_access, share_mode, creation_disposition, nullptr);
+#endif
+  if (handle == INVALID_HANDLE_VALUE) {
+    return OS_ERROR(PSLICE() << "File \"" << filepath << "\" can't be " << PrintFlags{flags});
+  }
+  if (flags & Append) {
+    LARGE_INTEGER offset;
+    offset.QuadPart = 0;
+    auto set_pointer_res = SetFilePointerEx(handle, offset, nullptr, FILE_END);
+    if (!set_pointer_res) {
+      auto res = OS_ERROR(PSLICE() << "Failed to seek to the end of file \"" << filepath << "\"");
+      CloseHandle(handle);
+      return res;
+    }
+  }
+  FileFd result;
+  result.fd_ = Fd::create_file_fd(handle);
+#endif
+  result.fd_.update_flags(Fd::Flag::Write);
+  return std::move(result);
+}
+
+Result<size_t> FileFd::write(Slice slice) {
+#if TD_PORT_POSIX
+  CHECK(!fd_.empty());
+  int native_fd = get_native_fd();
+  auto write_res = skip_eintr([&] { return ::write(native_fd, slice.begin(), slice.size()); });
+  if (write_res >= 0) {
+    return narrow_cast<size_t>(write_res);
+  }
+
+  auto write_errno = errno;
+  auto error = Status::PosixError(write_errno, PSLICE() << "Write to [fd = " << native_fd << "] has failed");
+  if (write_errno != EAGAIN
+#if EAGAIN != EWOULDBLOCK
+      && write_errno != EWOULDBLOCK
+#endif
+      && write_errno != EIO) {
+    LOG(ERROR) << error;
+  }
+  return std::move(error);
+#elif TD_PORT_WINDOWS
+  return fd_.write(slice);
+#endif
+}
+
+Result<size_t> FileFd::read(MutableSlice slice) {
+#if TD_PORT_POSIX
+  CHECK(!fd_.empty());
+  int native_fd = get_native_fd();
+  auto read_res = skip_eintr([&] { return ::read(native_fd, slice.begin(), slice.size()); });
+  auto read_errno = errno;
+
+  if (read_res >= 0) {
+    if (narrow_cast<size_t>(read_res) < slice.size()) {
+      fd_.clear_flags(Read);
+    }
+    return static_cast<size_t>(read_res);
+  }
+
+  auto error = Status::PosixError(read_errno, PSLICE() << "Read from [fd = " << native_fd << "] has failed");
+  if (read_errno != EAGAIN
+#if EAGAIN != EWOULDBLOCK
+      && read_errno != EWOULDBLOCK
+#endif
+      && read_errno != EIO) {
+    LOG(ERROR) << error;
+  }
+  return std::move(error);
+#elif TD_PORT_WINDOWS
+  return fd_.read(slice);
+#endif
+}
+
+Result<size_t> FileFd::pwrite(Slice slice, int64 offset) {
+  if (offset < 0) {
+    return Status::Error("Offset must be non-negative");
+  }
+#if TD_PORT_POSIX
+  TRY_RESULT(offset_off_t, narrow_cast_safe<off_t>(offset));
+  CHECK(!fd_.empty());
+  int native_fd = get_native_fd();
+  auto pwrite_res = skip_eintr([&] { return ::pwrite(native_fd, slice.begin(), slice.size(), offset_off_t); });
+  if (pwrite_res >= 0) {
+    return narrow_cast<size_t>(pwrite_res);
+  }
+
+  auto pwrite_errno = errno;
+  auto error = Status::PosixError(
+      pwrite_errno, PSLICE() << "Pwrite to [fd = " << native_fd << "] at [offset = " << offset << "] has failed");
+  if (pwrite_errno != EAGAIN
+#if EAGAIN != EWOULDBLOCK
+      && pwrite_errno != EWOULDBLOCK
+#endif
+      && pwrite_errno != EIO) {
+    LOG(ERROR) << error;
+  }
+  return std::move(error);
+#elif TD_PORT_WINDOWS
+  DWORD bytes_written = 0;
+  OVERLAPPED overlapped;
+  std::memset(&overlapped, 0, sizeof(overlapped));
+  overlapped.Offset = static_cast<DWORD>(offset);
+  overlapped.OffsetHigh = static_cast<DWORD>(offset >> 32);
+  auto res =
+      WriteFile(fd_.get_io_handle(), slice.data(), narrow_cast<DWORD>(slice.size()), &bytes_written, &overlapped);
+  if (!res) {
+    return OS_ERROR("Failed to pwrite");
+  }
+  return bytes_written;
+#endif
+}
+
+Result<size_t> FileFd::pread(MutableSlice slice, int64 offset) {
+  if (offset < 0) {
+    return Status::Error("Offset must be non-negative");
+  }
+#if TD_PORT_POSIX
+  TRY_RESULT(offset_off_t, narrow_cast_safe<off_t>(offset));
+  CHECK(!fd_.empty());
+  int native_fd = get_native_fd();
+  auto pread_res = skip_eintr([&] { return ::pread(native_fd, slice.begin(), slice.size(), offset_off_t); });
+  if (pread_res >= 0) {
+    return narrow_cast<size_t>(pread_res);
+  }
+
+  auto pread_errno = errno;
+  auto error = Status::PosixError(
+      pread_errno, PSLICE() << "Pread from [fd = " << native_fd << "] at [offset = " << offset << "] has failed");
+  if (pread_errno != EAGAIN
+#if EAGAIN != EWOULDBLOCK
+      && pread_errno != EWOULDBLOCK
+#endif
+      && pread_errno != EIO) {
+    LOG(ERROR) << error;
+  }
+  return std::move(error);
+#elif TD_PORT_WINDOWS
+  DWORD bytes_read = 0;
+  OVERLAPPED overlapped;
+  std::memset(&overlapped, 0, sizeof(overlapped));
+  overlapped.Offset = static_cast<DWORD>(offset);
+  overlapped.OffsetHigh = static_cast<DWORD>(offset >> 32);
+  auto res = ReadFile(fd_.get_io_handle(), slice.data(), narrow_cast<DWORD>(slice.size()), &bytes_read, &overlapped);
+  if (!res) {
+    return OS_ERROR("Failed to pread");
+  }
+  return bytes_read;
+#endif
+}
+
+Status FileFd::lock(FileFd::LockFlags flags, int32 max_tries) {
+  if (max_tries <= 0) {
+    return Status::Error(0, "Can't lock file: wrong max_tries");
+  }
+
+  while (true) {
+#if TD_PORT_POSIX
+    struct flock lock;
+    std::memset(&lock, 0, sizeof(lock));
+
+    lock.l_type = static_cast<short>([&] {
+      switch (flags) {
+        case LockFlags::Read:
+          return F_RDLCK;
+        case LockFlags::Write:
+          return F_WRLCK;
+        case LockFlags::Unlock:
+          return F_UNLCK;
+        default:
+          UNREACHABLE();
+          return F_UNLCK;
+      }
+    }());
+
+    lock.l_whence = SEEK_SET;
+    if (fcntl(get_native_fd(), F_SETLK, &lock) == -1) {
+      if (errno == EAGAIN && --max_tries > 0) {
+#elif TD_PORT_WINDOWS
+    OVERLAPPED overlapped;
+    std::memset(&overlapped, 0, sizeof(overlapped));
+
+    BOOL result;
+    if (flags == LockFlags::Unlock) {
+      result = UnlockFileEx(fd_.get_io_handle(), 0, MAXDWORD, MAXDWORD, &overlapped);
+    } else {
+      DWORD dw_flags = LOCKFILE_FAIL_IMMEDIATELY;
+      if (flags == LockFlags::Write) {
+        dw_flags |= LOCKFILE_EXCLUSIVE_LOCK;
+      }
+
+      result = LockFileEx(fd_.get_io_handle(), dw_flags, 0, MAXDWORD, MAXDWORD, &overlapped);
+    }
+
+    if (!result) {
+      if (GetLastError() == ERROR_LOCK_VIOLATION && --max_tries > 0) {
+#endif
+        usleep_for(100000);
+        continue;
+      }
+
+      return OS_ERROR("Can't lock file");
+    }
+    return Status::OK();
+  }
+}
+
+void FileFd::close() {
+  fd_.close();
+}
+
+bool FileFd::empty() const {
+  return fd_.empty();
+}
+
+#if TD_PORT_POSIX
+int FileFd::get_native_fd() const {
+  return fd_.get_native_fd();
+}
+#endif
+
+int32 FileFd::get_flags() const {
+  return fd_.get_flags();
+}
+
+void FileFd::update_flags(Fd::Flags mask) {
+  fd_.update_flags(mask);
+}
+
+int64 FileFd::get_size() {
+  return stat().size_;
+}
+
+#if TD_PORT_WINDOWS
+static uint64 filetime_to_unix_time_nsec(LONGLONG filetime) {
+  const auto FILETIME_UNIX_TIME_DIFF = 116444736000000000ll;
+  return static_cast<uint64>((filetime - FILETIME_UNIX_TIME_DIFF) * 100);
+}
+#endif
+
+Stat FileFd::stat() {
+  CHECK(!empty());
+#if TD_PORT_POSIX
+  return detail::fstat(get_native_fd());
+#elif TD_PORT_WINDOWS
+  Stat res;
+
+  FILE_BASIC_INFO basic_info;
+  auto status = GetFileInformationByHandleEx(fd_.get_io_handle(), FileBasicInfo, &basic_info, sizeof(basic_info));
+  if (!status) {
+    auto error = OS_ERROR("Stat failed");
+    LOG(FATAL) << error;
+  }
+  res.atime_nsec_ = filetime_to_unix_time_nsec(basic_info.LastAccessTime.QuadPart);
+  res.mtime_nsec_ = filetime_to_unix_time_nsec(basic_info.LastWriteTime.QuadPart);
+  res.is_dir_ = (basic_info.FileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
+  res.is_reg_ = true;
+
+  FILE_STANDARD_INFO standard_info;
+  status = GetFileInformationByHandleEx(fd_.get_io_handle(), FileStandardInfo, &standard_info, sizeof(standard_info));
+  if (!status) {
+    auto error = OS_ERROR("Stat failed");
+    LOG(FATAL) << error;
+  }
+  res.size_ = standard_info.EndOfFile.QuadPart;
+
+  return res;
+#endif
+}
+
+Status FileFd::sync() {
+  CHECK(!empty());
+#if TD_PORT_POSIX
+  if (fsync(fd_.get_native_fd()) != 0) {
+#elif TD_PORT_WINDOWS
+  if (FlushFileBuffers(fd_.get_io_handle()) == 0) {
+#endif
+    return OS_ERROR("Sync failed");
+  }
+  return Status::OK();
+}
+
+Status FileFd::seek(int64 position) {
+  CHECK(!empty());
+#if TD_PORT_POSIX
+  TRY_RESULT(position_off_t, narrow_cast_safe<off_t>(position));
+  if (skip_eintr([&] { return ::lseek(fd_.get_native_fd(), position_off_t, SEEK_SET); }) < 0) {
+#elif TD_PORT_WINDOWS
+  LARGE_INTEGER offset;
+  offset.QuadPart = position;
+  if (SetFilePointerEx(fd_.get_io_handle(), offset, nullptr, FILE_BEGIN) == 0) {
+#endif
+    return OS_ERROR("Seek failed");
+  }
+  return Status::OK();
+}
+
+Status FileFd::truncate_to_current_position(int64 current_position) {
+  CHECK(!empty());
+#if TD_PORT_POSIX
+  TRY_RESULT(current_position_off_t, narrow_cast_safe<off_t>(current_position));
+  if (skip_eintr([&] { return ::ftruncate(fd_.get_native_fd(), current_position_off_t); }) < 0) {
+#elif TD_PORT_WINDOWS
+  if (SetEndOfFile(fd_.get_io_handle()) == 0) {
+#endif
+    return OS_ERROR("Truncate failed");
+  }
+  return Status::OK();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/FileFd.h b/libs/tdlib/td/tdutils/td/utils/port/FileFd.h
new file mode 100644
index 0000000000..bf7166c1de
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/FileFd.h
@@ -0,0 +1,63 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#include "td/utils/common.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/Stat.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+class FileFd {
+ public:
+  FileFd() = default;
+
+  enum Flags : int32 { Write = 1, Read = 2, Truncate = 4, Create = 8, Append = 16, CreateNew = 32 };
+
+  const Fd &get_fd() const;
+  Fd &get_fd();
+
+  static Result<FileFd> open(CSlice filepath, int32 flags, int32 mode = 0600) TD_WARN_UNUSED_RESULT;
+
+  Result<size_t> write(Slice slice) TD_WARN_UNUSED_RESULT;
+  Result<size_t> read(MutableSlice slice) TD_WARN_UNUSED_RESULT;
+
+  Result<size_t> pwrite(Slice slice, int64 offset) TD_WARN_UNUSED_RESULT;
+  Result<size_t> pread(MutableSlice slice, int64 offset) TD_WARN_UNUSED_RESULT;
+
+  enum class LockFlags { Write, Read, Unlock };
+  Status lock(LockFlags flags, int32 max_tries = 1) TD_WARN_UNUSED_RESULT;
+
+  void close();
+  bool empty() const;
+
+  int32 get_flags() const;
+  void update_flags(Fd::Flags mask);
+
+  int64 get_size();
+
+  Stat stat();
+
+  Status sync() TD_WARN_UNUSED_RESULT;
+
+  Status seek(int64 position) TD_WARN_UNUSED_RESULT;
+
+  Status truncate_to_current_position(int64 current_position) TD_WARN_UNUSED_RESULT;
+
+#if TD_PORT_POSIX
+  int get_native_fd() const;
+#endif
+
+ private:
+  Fd fd_;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/IPAddress.cpp b/libs/tdlib/td/tdutils/td/utils/port/IPAddress.cpp
new file mode 100644
index 0000000000..2d3a3cdbc0
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/IPAddress.cpp
@@ -0,0 +1,361 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/IPAddress.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/SocketFd.h"
+#include "td/utils/port/thread_local.h"
+#include "td/utils/ScopeGuard.h"
+
+#if !TD_WINDOWS
+#include <netdb.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#endif
+
+#include <cstring>
+
+namespace td {
+
+IPAddress::IPAddress() : is_valid_(false) {
+}
+
+bool IPAddress::is_valid() const {
+  return is_valid_;
+}
+
+const sockaddr *IPAddress::get_sockaddr() const {
+  return &sockaddr_;
+}
+
+size_t IPAddress::get_sockaddr_len() const {
+  CHECK(is_valid());
+  switch (addr_.ss_family) {
+    case AF_INET6:
+      return sizeof(ipv6_addr_);
+    case AF_INET:
+      return sizeof(ipv4_addr_);
+    default:
+      LOG(FATAL) << "Unknown address family";
+      return 0;
+  }
+}
+
+int IPAddress::get_address_family() const {
+  return get_sockaddr()->sa_family;
+}
+
+bool IPAddress::is_ipv4() const {
+  return get_address_family() == AF_INET;
+}
+
+uint32 IPAddress::get_ipv4() const {
+  CHECK(is_valid());
+  CHECK(is_ipv4());
+  return ipv4_addr_.sin_addr.s_addr;
+}
+
+Slice IPAddress::get_ipv6() const {
+  static_assert(sizeof(ipv6_addr_.sin6_addr) == 16, "ipv6 size == 16");
+  CHECK(is_valid());
+  CHECK(!is_ipv4());
+  return Slice(ipv6_addr_.sin6_addr.s6_addr, 16);
+}
+
+IPAddress IPAddress::get_any_addr() const {
+  IPAddress res;
+  switch (get_address_family()) {
+    case AF_INET6:
+      res.init_ipv6_any();
+      break;
+    case AF_INET:
+      res.init_ipv4_any();
+      break;
+    default:
+      LOG(FATAL) << "Unknown address family";
+  }
+  return res;
+}
+void IPAddress::init_ipv4_any() {
+  is_valid_ = true;
+  ipv4_addr_.sin_family = AF_INET;
+  ipv4_addr_.sin_addr.s_addr = INADDR_ANY;
+  ipv4_addr_.sin_port = 0;
+}
+void IPAddress::init_ipv6_any() {
+  is_valid_ = true;
+  ipv6_addr_.sin6_family = AF_INET6;
+  ipv6_addr_.sin6_addr = in6addr_any;
+  ipv6_addr_.sin6_port = 0;
+}
+
+Status IPAddress::init_ipv6_port(CSlice ipv6, int port) {
+  is_valid_ = false;
+  if (port <= 0 || port >= (1 << 16)) {
+    return Status::Error(PSLICE() << "Invalid [port=" << port << "]");
+  }
+  std::memset(&ipv6_addr_, 0, sizeof(ipv6_addr_));
+  ipv6_addr_.sin6_family = AF_INET6;
+  ipv6_addr_.sin6_port = htons(static_cast<uint16>(port));
+  int err = inet_pton(AF_INET6, ipv6.c_str(), &ipv6_addr_.sin6_addr);
+  if (err == 0) {
+    return Status::Error(PSLICE() << "Failed inet_pton(AF_INET6, " << ipv6 << ")");
+  } else if (err == -1) {
+    return OS_SOCKET_ERROR(PSLICE() << "Failed inet_pton(AF_INET6, " << ipv6 << ")");
+  }
+  is_valid_ = true;
+  return Status::OK();
+}
+
+Status IPAddress::init_ipv6_as_ipv4_port(CSlice ipv4, int port) {
+  return init_ipv6_port(string("::FFFF:").append(ipv4.begin(), ipv4.size()), port);
+}
+
+Status IPAddress::init_ipv4_port(CSlice ipv4, int port) {
+  is_valid_ = false;
+  if (port <= 0 || port >= (1 << 16)) {
+    return Status::Error(PSLICE() << "Invalid [port=" << port << "]");
+  }
+  std::memset(&ipv4_addr_, 0, sizeof(ipv4_addr_));
+  ipv4_addr_.sin_family = AF_INET;
+  ipv4_addr_.sin_port = htons(static_cast<uint16>(port));
+  int err = inet_pton(AF_INET, ipv4.c_str(), &ipv4_addr_.sin_addr);
+  if (err == 0) {
+    return Status::Error(PSLICE() << "Failed inet_pton(AF_INET, " << ipv4 << ")");
+  } else if (err == -1) {
+    return OS_SOCKET_ERROR(PSLICE() << "Failed inet_pton(AF_INET, " << ipv4 << ")");
+  }
+  is_valid_ = true;
+  return Status::OK();
+}
+
+Status IPAddress::init_host_port(CSlice host, int port) {
+  auto str_port = to_string(port);
+  return init_host_port(host, str_port);
+}
+
+Status IPAddress::init_host_port(CSlice host, CSlice port) {
+  addrinfo hints;
+  addrinfo *info = nullptr;
+  std::memset(&hints, 0, sizeof(hints));
+  hints.ai_family = AF_INET;  // TODO AF_UNSPEC;
+  hints.ai_socktype = SOCK_STREAM;
+  LOG(INFO) << "Try to init IP address of " << host << " with port " << port;
+  auto s = getaddrinfo(host.c_str(), port.c_str(), &hints, &info);
+  if (s != 0) {
+    return Status::Error(PSLICE() << "getaddrinfo: " << gai_strerror(s));
+  }
+  SCOPE_EXIT {
+    freeaddrinfo(info);
+  };
+
+  // prefer ipv4
+  addrinfo *best_info = info;
+  for (auto *ptr = info->ai_next; ptr != nullptr; ptr = ptr->ai_next) {
+    if (ptr->ai_socktype == AF_INET) {
+      best_info = ptr;
+      break;
+    }
+  }
+  // just use first address
+  CHECK(best_info != nullptr);
+  return init_sockaddr(best_info->ai_addr, narrow_cast<socklen_t>(best_info->ai_addrlen));
+}
+
+Status IPAddress::init_host_port(CSlice host_port) {
+  auto pos = host_port.rfind(':');
+  if (pos == static_cast<size_t>(-1)) {
+    return Status::Error("Can't split string into host and port");
+  }
+  return init_host_port(host_port.substr(0, pos).str(), host_port.substr(pos + 1).str());
+}
+
+Status IPAddress::init_sockaddr(sockaddr *addr, socklen_t len) {
+  if (addr->sa_family == AF_INET6) {
+    CHECK(len == sizeof(ipv6_addr_));
+    std::memcpy(&ipv6_addr_, reinterpret_cast<sockaddr_in6 *>(addr), sizeof(ipv6_addr_));
+    LOG(INFO) << "Have ipv6 address " << get_ip_str() << " with port " << get_port();
+  } else if (addr->sa_family == AF_INET) {
+    CHECK(len == sizeof(ipv4_addr_));
+    std::memcpy(&ipv4_addr_, reinterpret_cast<sockaddr_in *>(addr), sizeof(ipv4_addr_));
+    LOG(INFO) << "Have ipv4 address " << get_ip_str() << " with port " << get_port();
+  } else {
+    return Status::Error(PSLICE() << "Unknown " << tag("sa_family", addr->sa_family));
+  }
+
+  is_valid_ = true;
+  return Status::OK();
+}
+
+Status IPAddress::init_socket_address(const SocketFd &socket_fd) {
+  is_valid_ = false;
+#if TD_WINDOWS
+  auto fd = socket_fd.get_fd().get_native_socket();
+#else
+  auto fd = socket_fd.get_fd().get_native_fd();
+#endif
+  socklen_t len = sizeof(addr_);
+  int ret = getsockname(fd, &sockaddr_, &len);
+  if (ret != 0) {
+    return OS_SOCKET_ERROR("Failed to get socket address");
+  }
+  is_valid_ = true;
+  return Status::OK();
+}
+
+Status IPAddress::init_peer_address(const SocketFd &socket_fd) {
+  is_valid_ = false;
+#if TD_WINDOWS
+  auto fd = socket_fd.get_fd().get_native_socket();
+#else
+  auto fd = socket_fd.get_fd().get_native_fd();
+#endif
+  socklen_t len = sizeof(addr_);
+  int ret = getpeername(fd, &sockaddr_, &len);
+  if (ret != 0) {
+    return OS_SOCKET_ERROR("Failed to get peer socket address");
+  }
+  is_valid_ = true;
+  return Status::OK();
+}
+
+static CSlice get_ip_str(int family, const void *addr) {
+  const int buf_size = INET6_ADDRSTRLEN;  //, INET_ADDRSTRLEN;
+  static TD_THREAD_LOCAL char *buf;
+  init_thread_local<char[]>(buf, buf_size);
+
+  const char *res = inet_ntop(family,
+#if TD_WINDOWS
+                              const_cast<PVOID>(addr),
+#else
+                              addr,
+#endif
+                              buf, buf_size);
+  if (res == nullptr) {
+    return CSlice();
+  } else {
+    return CSlice(res);
+  }
+}
+
+CSlice IPAddress::ipv4_to_str(int32 ipv4) {
+  auto tmp_ipv4 = ntohl(ipv4);
+  return ::td::get_ip_str(AF_INET, &tmp_ipv4);
+}
+
+Slice IPAddress::get_ip_str() const {
+  if (!is_valid()) {
+    return Slice("0.0.0.0");
+  }
+
+  const void *addr;
+  switch (get_address_family()) {
+    case AF_INET6:
+      addr = &ipv6_addr_.sin6_addr;
+      break;
+    case AF_INET:
+      addr = &ipv4_addr_.sin_addr;
+      break;
+    default:
+      UNREACHABLE();
+      return Slice();
+  }
+  return ::td::get_ip_str(get_address_family(), addr);
+}
+
+int IPAddress::get_port() const {
+  if (!is_valid()) {
+    return 0;
+  }
+
+  switch (get_address_family()) {
+    case AF_INET6:
+      return ntohs(ipv6_addr_.sin6_port);
+    case AF_INET:
+      return ntohs(ipv4_addr_.sin_port);
+    default:
+      UNREACHABLE();
+      return 0;
+  }
+}
+
+void IPAddress::set_port(int port) {
+  CHECK(is_valid());
+
+  switch (get_address_family()) {
+    case AF_INET6:
+      ipv6_addr_.sin6_port = htons(static_cast<uint16>(port));
+      break;
+    case AF_INET:
+      ipv4_addr_.sin_port = htons(static_cast<uint16>(port));
+      break;
+    default:
+      UNREACHABLE();
+  }
+}
+
+bool operator==(const IPAddress &a, const IPAddress &b) {
+  if (!a.is_valid() || !b.is_valid()) {
+    return false;
+  }
+  if (a.get_address_family() != b.get_address_family()) {
+    return false;
+  }
+
+  if (a.get_address_family() == AF_INET) {
+    return a.ipv4_addr_.sin_port == b.ipv4_addr_.sin_port &&
+           std::memcmp(&a.ipv4_addr_.sin_addr, &b.ipv4_addr_.sin_addr, sizeof(a.ipv4_addr_.sin_addr)) == 0;
+  } else if (a.get_address_family() == AF_INET6) {
+    return a.ipv6_addr_.sin6_port == b.ipv6_addr_.sin6_port &&
+           std::memcmp(&a.ipv6_addr_.sin6_addr, &b.ipv6_addr_.sin6_addr, sizeof(a.ipv6_addr_.sin6_addr)) == 0;
+  }
+
+  LOG(FATAL) << "Unknown address family";
+  return false;
+}
+
+bool operator<(const IPAddress &a, const IPAddress &b) {
+  if (a.is_valid() != b.is_valid()) {
+    return a.is_valid() < b.is_valid();
+  }
+  if (a.get_address_family() != b.get_address_family()) {
+    return a.get_address_family() < b.get_address_family();
+  }
+
+  if (a.get_address_family() == AF_INET) {
+    if (a.ipv4_addr_.sin_port != b.ipv4_addr_.sin_port) {
+      return a.ipv4_addr_.sin_port < b.ipv4_addr_.sin_port;
+    }
+    return std::memcmp(&a.ipv4_addr_.sin_addr, &b.ipv4_addr_.sin_addr, sizeof(a.ipv4_addr_.sin_addr)) < 0;
+  } else if (a.get_address_family() == AF_INET6) {
+    if (a.ipv6_addr_.sin6_port != b.ipv6_addr_.sin6_port) {
+      return a.ipv6_addr_.sin6_port < b.ipv6_addr_.sin6_port;
+    }
+    return std::memcmp(&a.ipv6_addr_.sin6_addr, &b.ipv6_addr_.sin6_addr, sizeof(a.ipv6_addr_.sin6_addr)) < 0;
+  }
+
+  LOG(FATAL) << "Unknown address family";
+  return false;
+}
+
+StringBuilder &operator<<(StringBuilder &builder, const IPAddress &address) {
+  if (!address.is_valid()) {
+    return builder << "[invalid]";
+  }
+  if (address.get_address_family() == AF_INET) {
+    return builder << "[" << address.get_ip_str() << ":" << address.get_port() << "]";
+  } else {
+    CHECK(address.get_address_family() == AF_INET6);
+    return builder << "[[" << address.get_ip_str() << "]:" << address.get_port() << "]";
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/IPAddress.h b/libs/tdlib/td/tdutils/td/utils/port/IPAddress.h
new file mode 100644
index 0000000000..116a4c5425
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/IPAddress.h
@@ -0,0 +1,71 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/StringBuilder.h"
+
+#if !TD_WINDOWS
+#include <arpa/inet.h>
+#include <sys/socket.h>
+#endif
+
+namespace td {
+class SocketFd;
+class IPAddress {
+ public:
+  IPAddress();
+
+  bool is_valid() const;
+
+  const sockaddr *get_sockaddr() const;
+  size_t get_sockaddr_len() const;
+  int get_address_family() const;
+  Slice get_ip_str() const;
+  bool is_ipv4() const;
+  uint32 get_ipv4() const;
+  Slice get_ipv6() const;
+  int get_port() const;
+  void set_port(int port);
+
+  IPAddress get_any_addr() const;
+
+  Status init_ipv6_port(CSlice ipv6, int port) TD_WARN_UNUSED_RESULT;
+  Status init_ipv6_as_ipv4_port(CSlice ipv4, int port) TD_WARN_UNUSED_RESULT;
+  Status init_ipv4_port(CSlice ipv4, int port) TD_WARN_UNUSED_RESULT;
+  Status init_host_port(CSlice host, int port) TD_WARN_UNUSED_RESULT;
+  Status init_host_port(CSlice host, CSlice port) TD_WARN_UNUSED_RESULT;
+  Status init_host_port(CSlice host_port) TD_WARN_UNUSED_RESULT;
+  Status init_socket_address(const SocketFd &socket_fd) TD_WARN_UNUSED_RESULT;
+  Status init_peer_address(const SocketFd &socket_fd) TD_WARN_UNUSED_RESULT;
+
+  friend bool operator==(const IPAddress &a, const IPAddress &b);
+  friend bool operator<(const IPAddress &a, const IPAddress &b);
+
+  static CSlice ipv4_to_str(int32 ipv4);
+
+ private:
+  union {
+    sockaddr_storage addr_;
+    sockaddr sockaddr_;
+    sockaddr_in ipv4_addr_;
+    sockaddr_in6 ipv6_addr_;
+  };
+  bool is_valid_;
+
+  Status init_sockaddr(sockaddr *addr, socklen_t len) TD_WARN_UNUSED_RESULT;
+  void init_ipv4_any();
+  void init_ipv6_any();
+};
+
+StringBuilder &operator<<(StringBuilder &builder, const IPAddress &address);
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/Poll.h b/libs/tdlib/td/tdutils/td/utils/port/Poll.h
new file mode 100644
index 0000000000..e23f4382d0
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/Poll.h
@@ -0,0 +1,35 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#include "td/utils/port/detail/Epoll.h"
+#include "td/utils/port/detail/KQueue.h"
+#include "td/utils/port/detail/Poll.h"
+#include "td/utils/port/detail/Select.h"
+#include "td/utils/port/detail/WineventPoll.h"
+
+namespace td {
+
+// clang-format off
+
+#if TD_POLL_EPOLL
+  using Poll = detail::Epoll;
+#elif TD_POLL_KQUEUE
+  using Poll = detail::KQueue;
+#elif TD_POLL_WINEVENT
+  using Poll = detail::WineventPoll;
+#elif TD_POLL_POLL
+  using Poll = detail::Poll;
+#elif TD_POLL_SELECT
+  using Poll = detail::Select;
+#endif
+
+// clang-format on
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/PollBase.h b/libs/tdlib/td/tdutils/td/utils/port/PollBase.h
new file mode 100644
index 0000000000..eb71367ab9
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/PollBase.h
@@ -0,0 +1,27 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/Fd.h"
+
+namespace td {
+class PollBase {
+ public:
+  PollBase() = default;
+  PollBase(const PollBase &) = delete;
+  PollBase &operator=(const PollBase &) = delete;
+  PollBase(PollBase &&) = default;
+  PollBase &operator=(PollBase &&) = default;
+  virtual ~PollBase() = default;
+  virtual void init() = 0;
+  virtual void clear() = 0;
+  virtual void subscribe(const Fd &fd, Fd::Flags flags) = 0;
+  virtual void unsubscribe(const Fd &fd) = 0;
+  virtual void unsubscribe_before_close(const Fd &fd) = 0;
+  virtual void run(int timeout_ms) = 0;
+};
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/RwMutex.h b/libs/tdlib/td/tdutils/td/utils/port/RwMutex.h
new file mode 100644
index 0000000000..eee5f3dcdb
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/RwMutex.h
@@ -0,0 +1,147 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/Status.h"
+
+#if TD_PORT_POSIX
+#include <pthread.h>
+#endif
+
+namespace td {
+class RwMutex {
+ public:
+  RwMutex() {
+    init();
+  }
+  RwMutex(const RwMutex &) = delete;
+  RwMutex &operator=(const RwMutex &) = delete;
+  RwMutex(RwMutex &&other) {
+    init();
+    other.clear();
+  }
+  RwMutex &operator=(RwMutex &&other) {
+    other.clear();
+    return *this;
+  }
+  ~RwMutex() {
+    clear();
+  }
+
+  bool empty() const {
+    return !is_valid_;
+  }
+
+  void init();
+
+  void clear();
+
+  struct ReadUnlock {
+    void operator()(RwMutex *ptr) {
+      ptr->unlock_read_unsafe();
+    }
+  };
+  struct WriteUnlock {
+    void operator()(RwMutex *ptr) {
+      ptr->unlock_write_unsafe();
+    }
+  };
+
+  using ReadLock = std::unique_ptr<RwMutex, ReadUnlock>;
+  using WriteLock = std::unique_ptr<RwMutex, WriteUnlock>;
+
+  Result<ReadLock> lock_read() TD_WARN_UNUSED_RESULT {
+    lock_read_unsafe();
+    return ReadLock(this);
+  }
+
+  Result<WriteLock> lock_write() TD_WARN_UNUSED_RESULT {
+    lock_write_unsafe();
+    return WriteLock(this);
+  }
+
+  void lock_read_unsafe();
+
+  void lock_write_unsafe();
+
+  void unlock_read_unsafe();
+
+  void unlock_write_unsafe();
+
+ private:
+  bool is_valid_ = false;
+#if TD_PORT_POSIX
+  pthread_rwlock_t mutex_;
+#elif TD_PORT_WINDOWS
+  unique_ptr<SRWLOCK> mutex_;
+#endif
+};
+
+inline void RwMutex::init() {
+  CHECK(empty());
+  is_valid_ = true;
+#if TD_PORT_POSIX
+  pthread_rwlock_init(&mutex_, nullptr);
+#elif TD_PORT_WINDOWS
+  mutex_ = make_unique<SRWLOCK>();
+  InitializeSRWLock(mutex_.get());
+#endif
+}
+
+inline void RwMutex::clear() {
+  if (is_valid_) {
+#if TD_PORT_POSIX
+    pthread_rwlock_destroy(&mutex_);
+#elif TD_PORT_WINDOWS
+    mutex_.release();
+#endif
+    is_valid_ = false;
+  }
+}
+
+inline void RwMutex::lock_read_unsafe() {
+  CHECK(!empty());
+// TODO error handling
+#if TD_PORT_POSIX
+  pthread_rwlock_rdlock(&mutex_);
+#elif TD_PORT_WINDOWS
+  AcquireSRWLockShared(mutex_.get());
+#endif
+}
+
+inline void RwMutex::lock_write_unsafe() {
+  CHECK(!empty());
+#if TD_PORT_POSIX
+  pthread_rwlock_wrlock(&mutex_);
+#elif TD_PORT_WINDOWS
+  AcquireSRWLockExclusive(mutex_.get());
+#endif
+}
+
+inline void RwMutex::unlock_read_unsafe() {
+  CHECK(!empty());
+#if TD_PORT_POSIX
+  pthread_rwlock_unlock(&mutex_);
+#elif TD_PORT_WINDOWS
+  ReleaseSRWLockShared(mutex_.get());
+#endif
+}
+
+inline void RwMutex::unlock_write_unsafe() {
+  CHECK(!empty());
+#if TD_PORT_POSIX
+  pthread_rwlock_unlock(&mutex_);
+#elif TD_PORT_WINDOWS
+  ReleaseSRWLockExclusive(mutex_.get());
+#endif
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/ServerSocketFd.cpp b/libs/tdlib/td/tdutils/td/utils/port/ServerSocketFd.cpp
new file mode 100644
index 0000000000..ead43a3d4b
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/ServerSocketFd.cpp
@@ -0,0 +1,160 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/ServerSocketFd.h"
+
+#include "td/utils/port/config.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/port/IPAddress.h"
+
+#if TD_PORT_POSIX
+
+#include <arpa/inet.h>
+#include <fcntl.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#endif
+
+namespace td {
+
+Result<ServerSocketFd> ServerSocketFd::open(int32 port, CSlice addr) {
+  ServerSocketFd socket;
+  TRY_STATUS(socket.init(port, addr));
+  return std::move(socket);
+}
+
+const Fd &ServerSocketFd::get_fd() const {
+  return fd_;
+}
+
+Fd &ServerSocketFd::get_fd() {
+  return fd_;
+}
+
+int32 ServerSocketFd::get_flags() const {
+  return fd_.get_flags();
+}
+
+Status ServerSocketFd::get_pending_error() {
+  return fd_.get_pending_error();
+}
+
+Result<SocketFd> ServerSocketFd::accept() {
+#if TD_PORT_POSIX
+  sockaddr_storage addr;
+  socklen_t addr_len = sizeof(addr);
+  int native_fd = fd_.get_native_fd();
+  int r_fd = skip_eintr([&] { return ::accept(native_fd, reinterpret_cast<sockaddr *>(&addr), &addr_len); });
+  auto accept_errno = errno;
+  if (r_fd >= 0) {
+    return SocketFd::from_native_fd(r_fd);
+  }
+
+  if (accept_errno == EAGAIN
+#if EAGAIN != EWOULDBLOCK
+      || accept_errno == EWOULDBLOCK
+#endif
+  ) {
+    fd_.clear_flags(Fd::Read);
+    return Status::Error(-1, "Operation would block");
+  }
+
+  auto error = Status::PosixError(accept_errno, PSLICE() << "Accept from [fd = " << native_fd << "] has failed");
+  switch (accept_errno) {
+    case EBADF:
+    case EFAULT:
+    case EINVAL:
+    case ENOTSOCK:
+    case EOPNOTSUPP:
+      LOG(FATAL) << error;
+      UNREACHABLE();
+      break;
+    default:
+      LOG(ERROR) << error;
+    // fallthrough
+    case EMFILE:
+    case ENFILE:
+    case ECONNABORTED:  //???
+      fd_.clear_flags(Fd::Read);
+      fd_.update_flags(Fd::Close);
+      return std::move(error);
+  }
+#elif TD_PORT_WINDOWS
+  TRY_RESULT(socket_fd, fd_.accept());
+  return SocketFd(std::move(socket_fd));
+#endif
+}
+
+void ServerSocketFd::close() {
+  fd_.close();
+}
+
+bool ServerSocketFd::empty() const {
+  return fd_.empty();
+}
+
+Status ServerSocketFd::init(int32 port, CSlice addr) {
+  IPAddress address;
+  TRY_STATUS(address.init_ipv4_port(addr, port));
+  auto fd = socket(address.get_address_family(), SOCK_STREAM, 0);
+#if TD_PORT_POSIX
+  if (fd == -1) {
+#elif TD_PORT_WINDOWS
+  if (fd == INVALID_SOCKET) {
+#endif
+    return OS_SOCKET_ERROR("Failed to create a socket");
+  }
+  auto fd_quard = ScopeExit() + [fd]() {
+#if TD_PORT_POSIX
+    ::close(fd);
+#elif TD_PORT_WINDOWS
+    ::closesocket(fd);
+#endif
+  };
+
+  TRY_STATUS(detail::set_native_socket_is_blocking(fd, false));
+
+  linger ling = {0, 0};
+#if TD_PORT_POSIX
+  int flags = 1;
+#ifdef SO_REUSEPORT
+  setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, reinterpret_cast<const char *>(&flags), sizeof(flags));
+#endif
+#elif TD_PORT_WINDOWS
+  BOOL flags = TRUE;
+#endif
+  setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, reinterpret_cast<const char *>(&flags), sizeof(flags));
+  setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, reinterpret_cast<const char *>(&flags), sizeof(flags));
+  setsockopt(fd, SOL_SOCKET, SO_LINGER, reinterpret_cast<const char *>(&ling), sizeof(ling));
+  setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, reinterpret_cast<const char *>(&flags), sizeof(flags));
+
+  int e_bind = bind(fd, address.get_sockaddr(), static_cast<socklen_t>(address.get_sockaddr_len()));
+  if (e_bind != 0) {
+    return OS_SOCKET_ERROR("Failed to bind a socket");
+  }
+
+  // TODO: magic constant
+  int e_listen = listen(fd, 8192);
+  if (e_listen != 0) {
+    return OS_SOCKET_ERROR("Failed to listen on a socket");
+  }
+
+#if TD_PORT_POSIX
+  fd_ = Fd(fd, Fd::Mode::Owner);
+#elif TD_PORT_WINDOWS
+  fd_ = Fd::create_server_socket_fd(fd, address.get_address_family());
+#endif
+
+  fd_quard.dismiss();
+  return Status::OK();
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/ServerSocketFd.h b/libs/tdlib/td/tdutils/td/utils/port/ServerSocketFd.h
new file mode 100644
index 0000000000..67b43ad02d
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/ServerSocketFd.h
@@ -0,0 +1,43 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/SocketFd.h"
+
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+class ServerSocketFd {
+ public:
+  ServerSocketFd() = default;
+  ServerSocketFd(const ServerSocketFd &) = delete;
+  ServerSocketFd &operator=(const ServerSocketFd &) = delete;
+  ServerSocketFd(ServerSocketFd &&) = default;
+  ServerSocketFd &operator=(ServerSocketFd &&) = default;
+
+  static Result<ServerSocketFd> open(int32 port, CSlice addr = CSlice("0.0.0.0")) TD_WARN_UNUSED_RESULT;
+
+  const Fd &get_fd() const;
+  Fd &get_fd();
+  int32 get_flags() const;
+  Status get_pending_error() TD_WARN_UNUSED_RESULT;
+
+  Result<SocketFd> accept() TD_WARN_UNUSED_RESULT;
+
+  void close();
+  bool empty() const;
+
+ private:
+  Fd fd_;
+
+  Status init(int32 port, CSlice addr) TD_WARN_UNUSED_RESULT;
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/SocketFd.cpp b/libs/tdlib/td/tdutils/td/utils/port/SocketFd.cpp
new file mode 100644
index 0000000000..790bcd1bbd
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/SocketFd.cpp
@@ -0,0 +1,139 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/SocketFd.h"
+
+#include "td/utils/logging.h"
+
+#if TD_PORT_WINDOWS
+#include "td/utils/misc.h"
+#endif
+
+#if TD_PORT_POSIX
+#include <arpa/inet.h>
+#include <fcntl.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+#endif
+
+namespace td {
+
+Result<SocketFd> SocketFd::open(const IPAddress &address) {
+  SocketFd socket;
+  TRY_STATUS(socket.init(address));
+  return std::move(socket);
+}
+
+#if TD_PORT_POSIX
+Result<SocketFd> SocketFd::from_native_fd(int fd) {
+  auto fd_guard = ScopeExit() + [fd]() { ::close(fd); };
+
+  TRY_STATUS(detail::set_native_socket_is_blocking(fd, false));
+
+  // TODO remove copypaste
+  int flags = 1;
+  setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, reinterpret_cast<const char *>(&flags), sizeof(flags));
+  setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, reinterpret_cast<const char *>(&flags), sizeof(flags));
+  setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, reinterpret_cast<const char *>(&flags), sizeof(flags));
+  // TODO: SO_REUSEADDR, SO_KEEPALIVE, TCP_NODELAY, SO_SNDBUF, SO_RCVBUF, TCP_QUICKACK, SO_LINGER
+
+  fd_guard.dismiss();
+
+  SocketFd socket;
+  socket.fd_ = Fd(fd, Fd::Mode::Owner);
+  return std::move(socket);
+}
+#endif
+
+Status SocketFd::init(const IPAddress &address) {
+  auto fd = socket(address.get_address_family(), SOCK_STREAM, 0);
+#if TD_PORT_POSIX
+  if (fd == -1) {
+#elif TD_PORT_WINDOWS
+  if (fd == INVALID_SOCKET) {
+#endif
+    return OS_SOCKET_ERROR("Failed to create a socket");
+  }
+  auto fd_quard = ScopeExit() + [fd]() {
+#if TD_PORT_POSIX
+    ::close(fd);
+#elif TD_PORT_WINDOWS
+    ::closesocket(fd);
+#endif
+  };
+
+  TRY_STATUS(detail::set_native_socket_is_blocking(fd, false));
+
+#if TD_PORT_POSIX
+  int flags = 1;
+#elif TD_PORT_WINDOWS
+  BOOL flags = TRUE;
+#endif
+  setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, reinterpret_cast<const char *>(&flags), sizeof(flags));
+  setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, reinterpret_cast<const char *>(&flags), sizeof(flags));
+  setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, reinterpret_cast<const char *>(&flags), sizeof(flags));
+  // TODO: SO_REUSEADDR, SO_KEEPALIVE, TCP_NODELAY, SO_SNDBUF, SO_RCVBUF, TCP_QUICKACK, SO_LINGER
+
+#if TD_PORT_POSIX
+  int e_connect = connect(fd, address.get_sockaddr(), static_cast<socklen_t>(address.get_sockaddr_len()));
+  if (e_connect == -1) {
+    auto connect_errno = errno;
+    if (connect_errno != EINPROGRESS) {
+      return Status::PosixError(connect_errno, PSLICE() << "Failed to connect to " << address);
+    }
+  }
+  fd_ = Fd(fd, Fd::Mode::Owner);
+#elif TD_PORT_WINDOWS
+  auto bind_addr = address.get_any_addr();
+  auto e_bind = bind(fd, bind_addr.get_sockaddr(), narrow_cast<int>(bind_addr.get_sockaddr_len()));
+  if (e_bind != 0) {
+    return OS_SOCKET_ERROR("Failed to bind a socket");
+  }
+
+  fd_ = Fd::create_socket_fd(fd);
+  fd_.connect(address);
+#endif
+
+  fd_quard.dismiss();
+  return Status::OK();
+}
+
+const Fd &SocketFd::get_fd() const {
+  return fd_;
+}
+
+Fd &SocketFd::get_fd() {
+  return fd_;
+}
+
+void SocketFd::close() {
+  fd_.close();
+}
+
+bool SocketFd::empty() const {
+  return fd_.empty();
+}
+
+int32 SocketFd::get_flags() const {
+  return fd_.get_flags();
+}
+
+Status SocketFd::get_pending_error() {
+  return fd_.get_pending_error();
+}
+
+Result<size_t> SocketFd::write(Slice slice) {
+  return fd_.write(slice);
+}
+
+Result<size_t> SocketFd::read(MutableSlice slice) {
+  return fd_.read(slice);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/SocketFd.h b/libs/tdlib/td/tdutils/td/utils/port/SocketFd.h
new file mode 100644
index 0000000000..c88dd7d789
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/SocketFd.h
@@ -0,0 +1,57 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/IPAddress.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+class SocketFd {
+ public:
+  SocketFd() = default;
+  SocketFd(const SocketFd &) = delete;
+  SocketFd &operator=(const SocketFd &) = delete;
+  SocketFd(SocketFd &&) = default;
+  SocketFd &operator=(SocketFd &&) = default;
+
+  static Result<SocketFd> open(const IPAddress &address) TD_WARN_UNUSED_RESULT;
+
+  const Fd &get_fd() const;
+  Fd &get_fd();
+
+  int32 get_flags() const;
+
+  Status get_pending_error() TD_WARN_UNUSED_RESULT;
+
+  Result<size_t> write(Slice slice) TD_WARN_UNUSED_RESULT;
+  Result<size_t> read(MutableSlice slice) TD_WARN_UNUSED_RESULT;
+
+  void close();
+  bool empty() const;
+
+ private:
+  Fd fd_;
+
+  friend class ServerSocketFd;
+
+  Status init(const IPAddress &address) TD_WARN_UNUSED_RESULT;
+
+#if TD_PORT_POSIX
+  static Result<SocketFd> from_native_fd(int fd);
+#endif
+#if TD_PORT_WINDOWS
+  explicit SocketFd(Fd fd) : fd_(std::move(fd)) {
+  }
+#endif
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/Stat.cpp b/libs/tdlib/td/tdutils/td/utils/port/Stat.cpp
new file mode 100644
index 0000000000..edc882761b
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/Stat.cpp
@@ -0,0 +1,337 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/Stat.h"
+
+#include "td/utils/port/FileFd.h"
+
+#if TD_PORT_POSIX
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/Clocks.h"
+#include "td/utils/ScopeGuard.h"
+
+#include <utility>
+
+#if TD_DARWIN
+#include <mach/mach.h>
+#include <sys/time.h>
+#endif
+
+// We don't want warnings from system headers
+#if TD_GCC
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wconversion"
+#endif
+#include <sys/stat.h>
+#if TD_GCC
+#pragma GCC diagnostic pop
+#endif
+
+#if TD_ANDROID || TD_TIZEN
+#include <sys/syscall.h>
+#endif
+
+namespace td {
+
+namespace detail {
+
+template <class...>
+struct voider {
+  using type = void;
+};
+template <class... T>
+using void_t = typename voider<T...>::type;
+
+template <class T, class = void>
+struct TimeNsec {
+  static std::pair<int, int> get(const T &) {
+    T().warning("Platform lacks support of precise access/modification file times, comment this line to continue");
+    return {0, 0};
+  }
+};
+
+template <class T>
+struct TimeNsec<T, void_t<char, decltype(T::st_atimespec), decltype(T::st_mtimespec)>> {
+  static std::pair<decltype(decltype(T::st_atimespec)::tv_nsec), decltype(decltype(T::st_mtimespec)::tv_nsec)> get(
+      const T &s) {
+    return {s.st_atimespec.tv_nsec, s.st_mtimespec.tv_nsec};
+  }
+};
+
+template <class T>
+struct TimeNsec<T, void_t<short, decltype(T::st_atimensec), decltype(T::st_mtimensec)>> {
+  static std::pair<decltype(T::st_atimensec), decltype(T::st_mtimensec)> get(const T &s) {
+    return {s.st_atimensec, s.st_mtimensec};
+  }
+};
+
+template <class T>
+struct TimeNsec<T, void_t<int, decltype(T::st_atim), decltype(T::st_mtim)>> {
+  static std::pair<decltype(decltype(T::st_atim)::tv_nsec), decltype(decltype(T::st_mtim)::tv_nsec)> get(const T &s) {
+    return {s.st_atim.tv_nsec, s.st_mtim.tv_nsec};
+  }
+};
+
+Stat from_native_stat(const struct ::stat &buf) {
+  auto time_nsec = TimeNsec<struct ::stat>::get(buf);
+
+  Stat res;
+  res.atime_nsec_ = static_cast<uint64>(buf.st_atime) * 1000000000 + time_nsec.first;
+  res.mtime_nsec_ = static_cast<uint64>(buf.st_mtime) * 1000000000 + time_nsec.second / 1000 * 1000;
+  res.size_ = buf.st_size;
+  res.is_dir_ = (buf.st_mode & S_IFMT) == S_IFDIR;
+  res.is_reg_ = (buf.st_mode & S_IFMT) == S_IFREG;
+  return res;
+}
+
+Stat fstat(int native_fd) {
+  struct ::stat buf;
+  int err = fstat(native_fd, &buf);
+  auto fstat_errno = errno;
+  LOG_IF(FATAL, err < 0) << Status::PosixError(fstat_errno, PSLICE() << "stat for fd " << native_fd << " failed");
+  return detail::from_native_stat(buf);
+}
+
+Status update_atime(int native_fd) {
+#if TD_LINUX
+  timespec times[2];
+  // access time
+  times[0].tv_nsec = UTIME_NOW;
+  // modify time
+  times[1].tv_nsec = UTIME_OMIT;
+  if (futimens(native_fd, times) < 0) {
+    auto status = OS_ERROR(PSLICE() << "futimens " << tag("fd", native_fd));
+    LOG(WARNING) << status;
+    return status;
+  }
+  return Status::OK();
+#elif TD_DARWIN
+  auto info = fstat(native_fd);
+  timeval upd[2];
+  auto now = Clocks::system();
+  // access time
+  upd[0].tv_sec = static_cast<decltype(upd[0].tv_sec)>(now);
+  upd[0].tv_usec = static_cast<decltype(upd[0].tv_usec)>((now - static_cast<double>(upd[0].tv_sec)) * 1000000);
+  // modify time
+  upd[1].tv_sec = static_cast<decltype(upd[1].tv_sec)>(info.mtime_nsec_ / 1000000000ll);
+  upd[1].tv_usec = static_cast<decltype(upd[1].tv_usec)>(info.mtime_nsec_ % 1000000000ll / 1000);
+  if (futimes(native_fd, upd) < 0) {
+    auto status = OS_ERROR(PSLICE() << "futimes " << tag("fd", native_fd));
+    LOG(WARNING) << status;
+    return status;
+  }
+  return Status::OK();
+#else
+  return Status::Error("Not supported");
+// timespec times[2];
+//// access time
+// times[0].tv_nsec = UTIME_NOW;
+//// modify time
+// times[1].tv_nsec = UTIME_OMIT;
+////  int err = syscall(__NR_utimensat, native_fd, nullptr, times, 0);
+// if (futimens(native_fd, times) < 0) {
+//   auto status = OS_ERROR(PSLICE() << "futimens " << tag("fd", native_fd));
+//   LOG(WARNING) << status;
+//   return status;
+// }
+// return Status::OK();
+#endif
+}
+}  // namespace detail
+
+Status update_atime(CSlice path) {
+  TRY_RESULT(file, FileFd::open(path, FileFd::Flags::Read));
+  SCOPE_EXIT {
+    file.close();
+  };
+  return detail::update_atime(file.get_native_fd());
+}
+
+Result<Stat> stat(CSlice path) {
+  struct ::stat buf;
+  if (stat(path.c_str(), &buf) < 0) {
+    return OS_ERROR(PSLICE() << "stat for " << tag("file", path) << " failed");
+  }
+  return detail::from_native_stat(buf);
+}
+
+Result<MemStat> mem_stat() {
+#if TD_DARWIN
+  task_basic_info t_info;
+  mach_msg_type_number_t t_info_count = TASK_BASIC_INFO_COUNT;
+
+  if (KERN_SUCCESS !=
+      task_info(mach_task_self(), TASK_BASIC_INFO, reinterpret_cast<task_info_t>(&t_info), &t_info_count)) {
+    return Status::Error("task_info failed");
+  }
+  MemStat res;
+  res.resident_size_ = t_info.resident_size;
+  res.virtual_size_ = t_info.virtual_size;
+  res.resident_size_peak_ = 0;
+  res.virtual_size_peak_ = 0;
+  return res;
+#elif TD_LINUX || TD_ANDROID || TD_TIZEN
+  TRY_RESULT(fd, FileFd::open("/proc/self/status", FileFd::Read));
+  SCOPE_EXIT {
+    fd.close();
+  };
+
+  constexpr int TMEM_SIZE = 10000;
+  char mem[TMEM_SIZE];
+  TRY_RESULT(size, fd.read(MutableSlice(mem, TMEM_SIZE - 1)));
+  CHECK(size < TMEM_SIZE - 1);
+  mem[size] = 0;
+
+  const char *s = mem;
+  MemStat res;
+  while (*s) {
+    const char *name_begin = s;
+    while (*s != 0 && *s != '\n') {
+      s++;
+    }
+    auto name_end = name_begin;
+    while (is_alpha(*name_end)) {
+      name_end++;
+    }
+    Slice name(name_begin, name_end);
+
+    uint64 *x = nullptr;
+    if (name == "VmPeak") {
+      x = &res.virtual_size_peak_;
+    }
+    if (name == "VmSize") {
+      x = &res.virtual_size_;
+    }
+    if (name == "VmHWM") {
+      x = &res.resident_size_peak_;
+    }
+    if (name == "VmRSS") {
+      x = &res.resident_size_;
+    }
+    if (x != nullptr) {
+      Slice value(name_end, s);
+      if (!value.empty() && value[0] == ':') {
+        value.remove_prefix(1);
+      }
+      value = trim(value);
+      value = split(value).first;
+      auto r_mem = to_integer_safe<uint64>(value);
+      if (r_mem.is_error()) {
+        LOG(ERROR) << "Failed to parse memory stats " << tag("name", name) << tag("value", value);
+        *x = static_cast<uint64>(-1);
+      } else {
+        *x = r_mem.ok() * 1024;  // memory is in kB
+      }
+    }
+    if (*s == 0) {
+      break;
+    }
+    s++;
+  }
+
+  return res;
+#else
+  return Status::Error("Not supported");
+#endif
+}
+
+#if TD_LINUX
+Status cpu_stat_self(CpuStat &stat) {
+  TRY_RESULT(fd, FileFd::open("/proc/self/stat", FileFd::Read));
+  SCOPE_EXIT {
+    fd.close();
+  };
+
+  constexpr int TMEM_SIZE = 10000;
+  char mem[TMEM_SIZE];
+  TRY_RESULT(size, fd.read(MutableSlice(mem, TMEM_SIZE - 1)));
+  CHECK(size < TMEM_SIZE - 1);
+  mem[size] = 0;
+
+  char *s = mem;
+  char *t = mem + size;
+  int pass_cnt = 0;
+
+  while (pass_cnt < 15) {
+    if (pass_cnt == 13) {
+      stat.process_user_ticks = to_integer<uint64>(Slice(s, t));
+    }
+    if (pass_cnt == 14) {
+      stat.process_system_ticks = to_integer<uint64>(Slice(s, t));
+    }
+    while (*s && *s != ' ') {
+      s++;
+    }
+    if (*s == ' ') {
+      s++;
+      pass_cnt++;
+    } else {
+      return Status::Error("unexpected end of proc file");
+    }
+  }
+  return Status::OK();
+}
+Status cpu_stat_total(CpuStat &stat) {
+  TRY_RESULT(fd, FileFd::open("/proc/stat", FileFd::Read));
+  SCOPE_EXIT {
+    fd.close();
+  };
+
+  constexpr int TMEM_SIZE = 10000;
+  char mem[TMEM_SIZE];
+  TRY_RESULT(size, fd.read(MutableSlice(mem, TMEM_SIZE - 1)));
+  CHECK(size < TMEM_SIZE - 1);
+  mem[size] = 0;
+
+  uint64 sum = 0, cur = 0;
+  for (size_t i = 0; i < size; i++) {
+    int c = mem[i];
+    if (c >= '0' && c <= '9') {
+      cur = cur * 10 + (uint64)c - '0';
+    } else {
+      sum += cur;
+      cur = 0;
+      if (c == '\n') {
+        break;
+      }
+    }
+  }
+
+  stat.total_ticks = sum;
+  return Status::OK();
+}
+#endif
+
+Result<CpuStat> cpu_stat() {
+#if TD_LINUX
+  CpuStat stat;
+  TRY_STATUS(cpu_stat_self(stat));
+  TRY_STATUS(cpu_stat_total(stat));
+  return stat;
+#else
+  return Status::Error("Not supported");
+#endif
+}
+}  // namespace td
+#endif
+
+#if TD_PORT_WINDOWS
+namespace td {
+
+Result<Stat> stat(CSlice path) {
+  TRY_RESULT(fd, FileFd::open(path, FileFd::Flags::Read));
+  return fd.stat();
+}
+
+Result<CpuStat> cpu_stat() {
+  return Status::Error("Not supported");
+}
+
+}  // namespace td
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/Stat.h b/libs/tdlib/td/tdutils/td/utils/port/Stat.h
new file mode 100644
index 0000000000..d0a98db141
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/Stat.h
@@ -0,0 +1,53 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+struct Stat {
+  bool is_dir_;
+  bool is_reg_;
+  int64 size_;
+  uint64 atime_nsec_;
+  uint64 mtime_nsec_;
+};
+
+Result<Stat> stat(CSlice path) TD_WARN_UNUSED_RESULT;
+
+struct CpuStat {
+  uint64 total_ticks{0};
+  uint64 process_user_ticks{0};
+  uint64 process_system_ticks{0};
+};
+Result<CpuStat> cpu_stat() TD_WARN_UNUSED_RESULT;
+
+#if TD_PORT_POSIX
+
+namespace detail {
+Stat fstat(int native_fd);  // TODO return Result<Stat>
+}  // namespace detail
+
+Status update_atime(CSlice path) TD_WARN_UNUSED_RESULT;
+
+struct MemStat {
+  uint64 resident_size_ = 0;
+  uint64 resident_size_peak_ = 0;
+  uint64 virtual_size_ = 0;
+  uint64 virtual_size_peak_ = 0;
+};
+
+Result<MemStat> mem_stat() TD_WARN_UNUSED_RESULT;
+
+#endif
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/config.h b/libs/tdlib/td/tdutils/td/utils/port/config.h
new file mode 100644
index 0000000000..0ffdb3c3bf
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/config.h
@@ -0,0 +1,46 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/platform.h"
+
+// clang-format off
+
+#if TD_WINDOWS
+  #define TD_PORT_WINDOWS 1
+#else
+  #define TD_PORT_POSIX 1
+#endif
+
+#if TD_LINUX || TD_ANDROID || TD_TIZEN
+  #define TD_POLL_EPOLL 1
+  #define TD_EVENTFD_LINUX 1
+#elif TD_CYGWIN
+  #define TD_POLL_SELECT 1
+  #define TD_EVENTFD_BSD 1
+#elif TD_EMSCRIPTEN
+  #define TD_POLL_POLL 1
+  #define TD_EVENTFD_UNSUPPORTED 1
+#elif TD_DARWIN
+  #define TD_POLL_KQUEUE 1
+  #define TD_EVENTFD_BSD 1
+#elif TD_WINDOWS
+  #define TD_POLL_WINEVENT 1
+  #define TD_EVENTFD_WINDOWS 1
+#else
+  #error "Poll's implementation is not defined"
+#endif
+
+#if TD_EMSCRIPTEN
+  #define TD_THREAD_UNSUPPORTED 1
+#elif TD_TIZEN
+  #define TD_THREAD_PTHREAD 1
+#else
+  #define TD_THREAD_STL 1
+#endif
+
+// clang-format on
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/Epoll.cpp b/libs/tdlib/td/tdutils/td/utils/port/detail/Epoll.cpp
new file mode 100644
index 0000000000..2ef026d164
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/Epoll.cpp
@@ -0,0 +1,114 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/detail/Epoll.h"
+
+char disable_linker_warning_about_empty_file_epoll_cpp TD_UNUSED;
+
+#ifdef TD_POLL_EPOLL
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/Status.h"
+
+#include <unistd.h>
+
+namespace td {
+namespace detail {
+void Epoll::init() {
+  CHECK(epoll_fd == -1);
+  epoll_fd = epoll_create(1);
+  auto epoll_create_errno = errno;
+  LOG_IF(FATAL, epoll_fd == -1) << Status::PosixError(epoll_create_errno, "epoll_create failed");
+
+  events.resize(1000);
+}
+
+void Epoll::clear() {
+  if (epoll_fd == -1) {
+    return;
+  }
+  events.clear();
+
+  close(epoll_fd);
+  epoll_fd = -1;
+}
+
+void Epoll::subscribe(const Fd &fd, Fd::Flags flags) {
+  epoll_event event;
+  event.events = EPOLLHUP | EPOLLERR | EPOLLET;
+#ifdef EPOLLRDHUP
+  event.events |= EPOLLRDHUP;
+#endif
+  if (flags & Fd::Read) {
+    event.events |= EPOLLIN;
+  }
+  if (flags & Fd::Write) {
+    event.events |= EPOLLOUT;
+  }
+  auto native_fd = fd.get_native_fd();
+  event.data.fd = native_fd;
+  int err = epoll_ctl(epoll_fd, EPOLL_CTL_ADD, native_fd, &event);
+  auto epoll_ctl_errno = errno;
+  LOG_IF(FATAL, err == -1) << Status::PosixError(epoll_ctl_errno, "epoll_ctl ADD failed") << ", epoll_fd = " << epoll_fd
+                           << ", fd = " << native_fd;
+}
+
+void Epoll::unsubscribe(const Fd &fd) {
+  auto native_fd = fd.get_native_fd();
+  int err = epoll_ctl(epoll_fd, EPOLL_CTL_DEL, native_fd, nullptr);
+  auto epoll_ctl_errno = errno;
+  LOG_IF(FATAL, err == -1) << Status::PosixError(epoll_ctl_errno, "epoll_ctl DEL failed") << ", epoll_fd = " << epoll_fd
+                           << ", fd = " << native_fd;
+}
+
+void Epoll::unsubscribe_before_close(const Fd &fd) {
+  unsubscribe(fd);
+}
+
+void Epoll::run(int timeout_ms) {
+  int ready_n = epoll_wait(epoll_fd, &events[0], static_cast<int>(events.size()), timeout_ms);
+  auto epoll_wait_errno = errno;
+  LOG_IF(FATAL, ready_n == -1 && epoll_wait_errno != EINTR)
+      << Status::PosixError(epoll_wait_errno, "epoll_wait failed");
+
+  for (int i = 0; i < ready_n; i++) {
+    Fd::Flags flags = 0;
+    epoll_event *event = &events[i];
+    if (event->events & EPOLLIN) {
+      event->events &= ~EPOLLIN;
+      flags |= Fd::Read;
+    }
+    if (event->events & EPOLLOUT) {
+      event->events &= ~EPOLLOUT;
+      flags |= Fd::Write;
+    }
+#ifdef EPOLLRDHUP
+    if (event->events & EPOLLRDHUP) {
+      event->events &= ~EPOLLRDHUP;
+      //      flags |= Fd::Close;
+      // TODO
+    }
+#endif
+    if (event->events & EPOLLHUP) {
+      event->events &= ~EPOLLHUP;
+      flags |= Fd::Close;
+    }
+    if (event->events & EPOLLERR) {
+      event->events &= ~EPOLLERR;
+      flags |= Fd::Error;
+    }
+    if (event->events) {
+      LOG(FATAL) << "Unsupported epoll events: " << event->events;
+    }
+    // LOG(DEBUG) << "Epoll event " << tag("fd", event->data.fd) << tag("flags", format::as_binary(flags));
+    Fd(event->data.fd, Fd::Mode::Reference).update_flags_notify(flags);
+  }
+}
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/Epoll.h b/libs/tdlib/td/tdutils/td/utils/port/detail/Epoll.h
new file mode 100644
index 0000000000..db4f66e5a7
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/Epoll.h
@@ -0,0 +1,51 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#ifdef TD_POLL_EPOLL
+
+#include "td/utils/common.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/PollBase.h"
+
+#include <sys/epoll.h>
+
+namespace td {
+namespace detail {
+
+class Epoll final : public PollBase {
+ public:
+  Epoll() = default;
+  Epoll(const Epoll &) = delete;
+  Epoll &operator=(const Epoll &) = delete;
+  Epoll(Epoll &&) = delete;
+  Epoll &operator=(Epoll &&) = delete;
+  ~Epoll() override = default;
+
+  void init() override;
+
+  void clear() override;
+
+  void subscribe(const Fd &fd, Fd::Flags flags) override;
+
+  void unsubscribe(const Fd &fd) override;
+
+  void unsubscribe_before_close(const Fd &fd) override;
+
+  void run(int timeout_ms) override;
+
+ private:
+  int epoll_fd = -1;
+  vector<struct epoll_event> events;
+};
+
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdBsd.cpp b/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdBsd.cpp
new file mode 100644
index 0000000000..d51e99ac0a
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdBsd.cpp
@@ -0,0 +1,93 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/detail/EventFdBsd.h"
+
+char disable_linker_warning_about_empty_file_event_fd_bsd_cpp TD_UNUSED;
+
+#ifdef TD_EVENTFD_BSD
+
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+
+#include <fcntl.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+
+namespace td {
+namespace detail {
+
+// TODO: it is extremely non optimal on Darwin. kqueue events should be used instead
+void EventFdBsd::init() {
+  int fds[2];
+  int err = socketpair(AF_UNIX, SOCK_STREAM, 0, fds);
+  auto socketpair_errno = errno;
+#if TD_CYGWIN
+  // it looks like CYGWIN bug
+  int max_retries = 1000000;
+  while (err == -1 && socketpair_errno == EADDRINUSE && max_retries-- > 0) {
+    err = socketpair(AF_UNIX, SOCK_STREAM, 0, fds);
+    socketpair_errno = errno;
+  }
+// LOG_IF(ERROR, max_retries < 1000000) << max_retries;
+#endif
+  LOG_IF(FATAL, err == -1) << Status::PosixError(socketpair_errno, "socketpair failed");
+
+  detail::set_native_socket_is_blocking(fds[0], false).ensure();
+  detail::set_native_socket_is_blocking(fds[1], false).ensure();
+
+  in_ = Fd(fds[0], Fd::Mode::Owner);
+  out_ = Fd(fds[1], Fd::Mode::Owner);
+}
+
+bool EventFdBsd::empty() {
+  return in_.empty();
+}
+
+void EventFdBsd::close() {
+  in_.close();
+  out_.close();
+}
+
+Status EventFdBsd::get_pending_error() {
+  return Status::OK();
+}
+
+const Fd &EventFdBsd::get_fd() const {
+  return out_;
+}
+
+Fd &EventFdBsd::get_fd() {
+  return out_;
+}
+
+void EventFdBsd::release() {
+  int value = 1;
+  auto result = in_.write(Slice(reinterpret_cast<const char *>(&value), sizeof(value)));
+  if (result.is_error()) {
+    LOG(FATAL) << "EventFdBsd write failed: " << result.error();
+  }
+  size_t size = result.ok();
+  if (size != sizeof(value)) {
+    LOG(FATAL) << "EventFdBsd write returned " << value << " instead of " << sizeof(value);
+  }
+}
+
+void EventFdBsd::acquire() {
+  out_.update_flags(Fd::Read);
+  while (can_read(out_)) {
+    uint8 value[1024];
+    auto result = out_.read(MutableSlice(value, sizeof(value)));
+    if (result.is_error()) {
+      LOG(FATAL) << "EventFdBsd read failed:" << result.error();
+    }
+  }
+}
+
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdBsd.h b/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdBsd.h
new file mode 100644
index 0000000000..08f7ddd308
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdBsd.h
@@ -0,0 +1,47 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#ifdef TD_EVENTFD_BSD
+
+#include "td/utils/common.h"
+#include "td/utils/port/EventFdBase.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/Status.h"
+
+namespace td {
+namespace detail {
+
+class EventFdBsd final : public EventFdBase {
+  Fd in_;
+  Fd out_;
+
+ public:
+  EventFdBsd() = default;
+
+  void init() override;
+
+  bool empty() override;
+
+  void close() override;
+
+  Status get_pending_error() override TD_WARN_UNUSED_RESULT;
+
+  const Fd &get_fd() const override;
+  Fd &get_fd() override;
+
+  void release() override;
+
+  void acquire() override;
+};
+
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdLinux.cpp b/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdLinux.cpp
new file mode 100644
index 0000000000..fd08c9af08
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdLinux.cpp
@@ -0,0 +1,74 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/detail/EventFdLinux.h"
+
+char disable_linker_warning_about_empty_file_event_fd_linux_cpp TD_UNUSED;
+
+#ifdef TD_EVENTFD_LINUX
+
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+
+#include <sys/eventfd.h>
+
+namespace td {
+namespace detail {
+
+void EventFdLinux::init() {
+  int fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
+  auto eventfd_errno = errno;
+  LOG_IF(FATAL, fd == -1) << Status::PosixError(eventfd_errno, "eventfd call failed");
+
+  fd_ = Fd(fd, Fd::Mode::Owner);
+}
+
+bool EventFdLinux::empty() {
+  return fd_.empty();
+}
+
+void EventFdLinux::close() {
+  fd_.close();
+}
+
+Status EventFdLinux::get_pending_error() {
+  return Status::OK();
+}
+
+const Fd &EventFdLinux::get_fd() const {
+  return fd_;
+}
+
+Fd &EventFdLinux::get_fd() {
+  return fd_;
+}
+
+void EventFdLinux::release() {
+  const uint64 value = 1;
+  // NB: write_unsafe is used, because release will be called from multiple threads
+  auto result = fd_.write_unsafe(Slice(reinterpret_cast<const char *>(&value), sizeof(value)));
+  if (result.is_error()) {
+    LOG(FATAL) << "EventFdLinux write failed: " << result.error();
+  }
+  size_t size = result.ok();
+  if (size != sizeof(value)) {
+    LOG(FATAL) << "EventFdLinux write returned " << value << " instead of " << sizeof(value);
+  }
+}
+
+void EventFdLinux::acquire() {
+  uint64 res;
+  auto result = fd_.read(MutableSlice(reinterpret_cast<char *>(&res), sizeof(res)));
+  if (result.is_error()) {
+    LOG(FATAL) << "EventFdLinux read failed: " << result.error();
+  }
+  fd_.clear_flags(Fd::Read);
+}
+
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdLinux.h b/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdLinux.h
new file mode 100644
index 0000000000..3df7ce3a5d
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdLinux.h
@@ -0,0 +1,44 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#ifdef TD_EVENTFD_LINUX
+
+#include "td/utils/common.h"
+#include "td/utils/port/EventFdBase.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/Status.h"
+
+namespace td {
+namespace detail {
+
+class EventFdLinux final : public EventFdBase {
+  Fd fd_;
+
+ public:
+  void init() override;
+
+  bool empty() override;
+
+  void close() override;
+
+  Status get_pending_error() override TD_WARN_UNUSED_RESULT;
+
+  const Fd &get_fd() const override;
+  Fd &get_fd() override;
+
+  void release() override;
+
+  void acquire() override;
+};
+
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdWindows.cpp b/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdWindows.cpp
new file mode 100644
index 0000000000..8adfd5a686
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdWindows.cpp
@@ -0,0 +1,51 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/detail/EventFdWindows.h"
+
+char disable_linker_warning_about_empty_file_event_fd_windows_cpp TD_UNUSED;
+
+#ifdef TD_EVENTFD_WINDOWS
+
+namespace td {
+namespace detail {
+
+void EventFdWindows::init() {
+  fd_ = Fd::create_event_fd();
+}
+
+bool EventFdWindows::empty() {
+  return fd_.empty();
+}
+
+void EventFdWindows::close() {
+  fd_.close();
+}
+
+Status EventFdWindows::get_pending_error() {
+  return Status::OK();
+}
+
+const Fd &EventFdWindows::get_fd() const {
+  return fd_;
+}
+
+Fd &EventFdWindows::get_fd() {
+  return fd_;
+}
+
+void EventFdWindows::release() {
+  fd_.release();
+}
+
+void EventFdWindows::acquire() {
+  fd_.acquire();
+}
+
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdWindows.h b/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdWindows.h
new file mode 100644
index 0000000000..48e1c763b3
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/EventFdWindows.h
@@ -0,0 +1,46 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#ifdef TD_EVENTFD_WINDOWS
+
+#include "td/utils/common.h"
+#include "td/utils/port/EventFdBase.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/Status.h"
+
+namespace td {
+namespace detail {
+
+class EventFdWindows final : public EventFdBase {
+  Fd fd_;
+
+ public:
+  EventFdWindows() = default;
+
+  void init() override;
+
+  bool empty() override;
+
+  void close() override;
+
+  Status get_pending_error() override TD_WARN_UNUSED_RESULT;
+
+  const Fd &get_fd() const override;
+  Fd &get_fd() override;
+
+  void release() override;
+
+  void acquire() override;
+};
+
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/KQueue.cpp b/libs/tdlib/td/tdutils/td/utils/port/detail/KQueue.cpp
new file mode 100644
index 0000000000..351f8d7d6c
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/KQueue.cpp
@@ -0,0 +1,160 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/detail/KQueue.h"
+
+char disable_linker_warning_about_empty_file_kqueue_cpp TD_UNUSED;
+
+#ifdef TD_POLL_KQUEUE
+
+#include "td/utils/logging.h"
+#include "td/utils/Status.h"
+
+#include <utility>
+
+#include <unistd.h>
+
+namespace td {
+namespace detail {
+
+KQueue::KQueue() {
+  kq = -1;
+}
+KQueue::~KQueue() {
+  clear();
+}
+void KQueue::init() {
+  kq = kqueue();
+  auto kqueue_errno = errno;
+  LOG_IF(FATAL, kq == -1) << Status::PosixError(kqueue_errno, "kqueue creation failed");
+
+  // TODO: const
+  events.resize(1000);
+  changes_n = 0;
+}
+
+void KQueue::clear() {
+  if (kq == -1) {
+    return;
+  }
+  events.clear();
+  close(kq);
+  kq = -1;
+}
+
+int KQueue::update(int nevents, const timespec *timeout, bool may_fail) {
+  int err = kevent(kq, &events[0], changes_n, &events[0], nevents, timeout);
+  auto kevent_errno = errno;
+
+  bool is_fatal_error = [&] {
+    if (err != -1) {
+      return false;
+    }
+    if (may_fail) {
+      return kevent_errno != ENOENT;
+    }
+    return kevent_errno != EINTR;
+  }();
+  LOG_IF(FATAL, is_fatal_error) << Status::PosixError(kevent_errno, "kevent failed");
+
+  changes_n = 0;
+  if (err < 0) {
+    return 0;
+  }
+  return err;
+}
+
+void KQueue::flush_changes(bool may_fail) {
+  if (!changes_n) {
+    return;
+  }
+  int n = update(0, nullptr, may_fail);
+  CHECK(n == 0);
+}
+
+void KQueue::add_change(std::uintptr_t ident, int16 filter, uint16 flags, uint32 fflags, std::intptr_t data,
+                        void *udata) {
+  if (changes_n == static_cast<int>(events.size())) {
+    flush_changes();
+  }
+  EV_SET(&events[changes_n], ident, filter, flags, fflags, data, udata);
+  VLOG(fd) << "Subscribe [fd:" << ident << "] [filter:" << filter << "] [udata: " << udata << "]";
+  changes_n++;
+}
+
+void KQueue::subscribe(const Fd &fd, Fd::Flags flags) {
+  if (flags & Fd::Read) {
+    add_change(fd.get_native_fd(), EVFILT_READ, EV_ADD | EV_CLEAR, 0, 0, nullptr);
+  }
+  if (flags & Fd::Write) {
+    add_change(fd.get_native_fd(), EVFILT_WRITE, EV_ADD | EV_CLEAR, 0, 0, nullptr);
+  }
+}
+
+void KQueue::invalidate(const Fd &fd) {
+  for (int i = 0; i < changes_n; i++) {
+    if (events[i].ident == static_cast<std::uintptr_t>(fd.get_native_fd())) {
+      changes_n--;
+      std::swap(events[i], events[changes_n]);
+      i--;
+    }
+  }
+}
+
+void KQueue::unsubscribe(const Fd &fd) {
+  // invalidate(fd);
+  flush_changes();
+  add_change(fd.get_native_fd(), EVFILT_READ, EV_DELETE, 0, 0, nullptr);
+  flush_changes(true);
+  add_change(fd.get_native_fd(), EVFILT_WRITE, EV_DELETE, 0, 0, nullptr);
+  flush_changes(true);
+}
+
+void KQueue::unsubscribe_before_close(const Fd &fd) {
+  invalidate(fd);
+
+  // just to avoid O(changes_n ^ 2)
+  if (changes_n != 0) {
+    flush_changes();
+  }
+}
+
+void KQueue::run(int timeout_ms) {
+  timespec timeout_data;
+  timespec *timeout_ptr;
+  if (timeout_ms == -1) {
+    timeout_ptr = nullptr;
+  } else {
+    timeout_data.tv_sec = timeout_ms / 1000;
+    timeout_data.tv_nsec = timeout_ms % 1000 * 1000000;
+    timeout_ptr = &timeout_data;
+  }
+
+  int n = update(static_cast<int>(events.size()), timeout_ptr);
+  for (int i = 0; i < n; i++) {
+    struct kevent *event = &events[i];
+    Fd::Flags flags = 0;
+    if (event->filter == EVFILT_WRITE) {
+      flags |= Fd::Write;
+    }
+    if (event->filter == EVFILT_READ) {
+      flags |= Fd::Read;
+    }
+    if (event->flags & EV_EOF) {
+      flags |= Fd::Close;
+    }
+    if (event->fflags & EV_ERROR) {
+      LOG(FATAL) << "EV_ERROR in kqueue is not supported";
+    }
+    VLOG(fd) << "Event [fd:" << event->ident << "] [filter:" << event->filter << "] [udata: " << event->udata << "]";
+    // LOG(WARNING) << "event->ident = " << event->ident << "event->filter = " << event->filter;
+    Fd(static_cast<int>(event->ident), Fd::Mode::Reference).update_flags_notify(flags);
+  }
+}
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/KQueue.h b/libs/tdlib/td/tdutils/td/utils/port/detail/KQueue.h
new file mode 100644
index 0000000000..e1b71e5fa5
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/KQueue.h
@@ -0,0 +1,62 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#ifdef TD_POLL_KQUEUE
+
+#include "td/utils/common.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/PollBase.h"
+
+#include <cstdint>
+
+#include <sys/event.h>
+
+namespace td {
+namespace detail {
+
+class KQueue final : public PollBase {
+ public:
+  KQueue();
+  KQueue(const KQueue &) = delete;
+  KQueue &operator=(const KQueue &) = delete;
+  KQueue(KQueue &&) = delete;
+  KQueue &operator=(KQueue &&) = delete;
+  ~KQueue() override;
+
+  void init() override;
+
+  void clear() override;
+
+  void subscribe(const Fd &fd, Fd::Flags flags) override;
+
+  void unsubscribe(const Fd &fd) override;
+
+  void unsubscribe_before_close(const Fd &fd) override;
+
+  void run(int timeout_ms) override;
+
+ private:
+  vector<struct kevent> events;
+  int changes_n;
+  int kq;
+
+  int update(int nevents, const timespec *timeout, bool may_fail = false);
+
+  void invalidate(const Fd &fd);
+
+  void flush_changes(bool may_fail = false);
+
+  void add_change(std::uintptr_t ident, int16 filter, uint16 flags, uint32 fflags, std::intptr_t data, void *udata);
+};
+
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/Poll.cpp b/libs/tdlib/td/tdutils/td/utils/port/detail/Poll.cpp
new file mode 100644
index 0000000000..87a7391802
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/Poll.cpp
@@ -0,0 +1,92 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/detail/Poll.h"
+
+char disable_linker_warning_about_empty_file_poll_cpp TD_UNUSED;
+
+#ifdef TD_POLL_POLL
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Status.h"
+
+namespace td {
+namespace detail {
+
+void Poll::init() {
+}
+
+void Poll::clear() {
+  pollfds_.clear();
+}
+
+void Poll::subscribe(const Fd &fd, Fd::Flags flags) {
+  unsubscribe(fd);
+  struct pollfd pollfd;
+  pollfd.fd = fd.get_native_fd();
+  pollfd.events = 0;
+  if (flags & Fd::Read) {
+    pollfd.events |= POLLIN;
+  }
+  if (flags & Fd::Write) {
+    pollfd.events |= POLLOUT;
+  }
+  pollfd.revents = 0;
+  pollfds_.push_back(pollfd);
+}
+
+void Poll::unsubscribe(const Fd &fd) {
+  for (auto it = pollfds_.begin(); it != pollfds_.end(); ++it) {
+    if (it->fd == fd.get_native_fd()) {
+      pollfds_.erase(it);
+      return;
+    }
+  }
+}
+
+void Poll::unsubscribe_before_close(const Fd &fd) {
+  unsubscribe(fd);
+}
+
+void Poll::run(int timeout_ms) {
+  int err = poll(pollfds_.data(), narrow_cast<int>(pollfds_.size()), timeout_ms);
+  auto poll_errno = errno;
+  LOG_IF(FATAL, err == -1 && poll_errno != EINTR) << Status::PosixError(poll_errno, "poll failed");
+
+  for (auto &pollfd : pollfds_) {
+    Fd::Flags flags = 0;
+    if (pollfd.revents & POLLIN) {
+      pollfd.revents &= ~POLLIN;
+      flags |= Fd::Read;
+    }
+    if (pollfd.revents & POLLOUT) {
+      pollfd.revents &= ~POLLOUT;
+      flags |= Fd::Write;
+    }
+    if (pollfd.revents & POLLHUP) {
+      pollfd.revents &= ~POLLHUP;
+      flags |= Fd::Close;
+    }
+    if (pollfd.revents & POLLERR) {
+      pollfd.revents &= ~POLLERR;
+      flags |= Fd::Error;
+    }
+    if (pollfd.revents & POLLNVAL) {
+      LOG(FATAL) << "Unexpected POLLNVAL " << tag("fd", pollfd.fd);
+    }
+    if (pollfd.revents) {
+      LOG(FATAL) << "Unsupported poll events: " << pollfd.revents;
+    }
+    Fd(pollfd.fd, Fd::Mode::Reference).update_flags_notify(flags);
+  }
+}
+
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/Poll.h b/libs/tdlib/td/tdutils/td/utils/port/detail/Poll.h
new file mode 100644
index 0000000000..32eca75399
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/Poll.h
@@ -0,0 +1,50 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#ifdef TD_POLL_POLL
+
+#include "td/utils/common.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/PollBase.h"
+
+#include <poll.h>
+
+namespace td {
+namespace detail {
+
+class Poll final : public PollBase {
+ public:
+  Poll() = default;
+  Poll(const Poll &) = delete;
+  Poll &operator=(const Poll &) = delete;
+  Poll(Poll &&) = delete;
+  Poll &operator=(Poll &&) = delete;
+  ~Poll() override = default;
+
+  void init() override;
+
+  void clear() override;
+
+  void subscribe(const Fd &fd, Fd::Flags flags) override;
+
+  void unsubscribe(const Fd &fd) override;
+
+  void unsubscribe_before_close(const Fd &fd) override;
+
+  void run(int timeout_ms) override;
+
+ private:
+  vector<pollfd> pollfds_;
+};
+
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/Select.cpp b/libs/tdlib/td/tdutils/td/utils/port/detail/Select.cpp
new file mode 100644
index 0000000000..b532a0464c
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/Select.cpp
@@ -0,0 +1,119 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/detail/Select.h"
+
+char disable_linker_warning_about_empty_file_select_cpp TD_UNUSED;
+
+#ifdef TD_POLL_SELECT
+
+#include "td/utils/logging.h"
+
+#include <utility>
+
+namespace td {
+namespace detail {
+
+void Select::init() {
+  FD_ZERO(&all_fd_);
+  FD_ZERO(&read_fd_);
+  FD_ZERO(&write_fd_);
+  FD_ZERO(&except_fd_);
+  max_fd_ = -1;
+}
+
+void Select::clear() {
+  fds_.clear();
+}
+
+void Select::subscribe(const Fd &fd, Fd::Flags flags) {
+  int native_fd = fd.get_native_fd();
+  for (auto &it : fds_) {
+    CHECK(it.fd_ref.get_native_fd() != native_fd);
+  }
+  fds_.push_back(FdInfo{Fd(native_fd, Fd::Mode::Reference), flags});
+  CHECK(0 <= native_fd && native_fd < FD_SETSIZE) << native_fd << " " << FD_SETSIZE;
+  FD_SET(native_fd, &all_fd_);
+  if (native_fd > max_fd_) {
+    max_fd_ = native_fd;
+  }
+}
+
+void Select::unsubscribe(const Fd &fd) {
+  int native_fd = fd.get_native_fd();
+  CHECK(0 <= native_fd && native_fd < FD_SETSIZE) << native_fd << " " << FD_SETSIZE;
+  FD_CLR(native_fd, &all_fd_);
+  FD_CLR(native_fd, &read_fd_);
+  FD_CLR(native_fd, &write_fd_);
+  FD_CLR(native_fd, &except_fd_);
+  while (max_fd_ >= 0 && !FD_ISSET(max_fd_, &all_fd_)) {
+    max_fd_--;
+  }
+  for (auto it = fds_.begin(); it != fds_.end();) {
+    if (it->fd_ref.get_native_fd() == native_fd) {
+      std::swap(*it, fds_.back());
+      fds_.pop_back();
+      break;
+    } else {
+      it++;
+    }
+  }
+}
+
+void Select::unsubscribe_before_close(const Fd &fd) {
+  unsubscribe(fd);
+}
+
+void Select::run(int timeout_ms) {
+  timeval timeout_data;
+  timeval *timeout_ptr;
+  if (timeout_ms == -1) {
+    timeout_ptr = nullptr;
+  } else {
+    timeout_data.tv_sec = timeout_ms / 1000;
+    timeout_data.tv_usec = timeout_ms % 1000 * 1000;
+    timeout_ptr = &timeout_data;
+  }
+
+  for (auto &it : fds_) {
+    int native_fd = it.fd_ref.get_native_fd();
+    Fd::Flags fd_flags = it.fd_ref.get_flags();
+    if ((it.flags & Fd::Write) && !(fd_flags & Fd::Write)) {
+      FD_SET(native_fd, &write_fd_);
+    } else {
+      FD_CLR(native_fd, &write_fd_);
+    }
+    if ((it.flags & Fd::Read) && !(fd_flags & Fd::Read)) {
+      FD_SET(native_fd, &read_fd_);
+    } else {
+      FD_CLR(native_fd, &read_fd_);
+    }
+    FD_SET(native_fd, &except_fd_);
+  }
+
+  select(max_fd_ + 1, &read_fd_, &write_fd_, &except_fd_, timeout_ptr);
+  for (auto &it : fds_) {
+    int native_fd = it.fd_ref.get_native_fd();
+    Fd::Flags flags = 0;
+    if (FD_ISSET(native_fd, &read_fd_)) {
+      flags |= Fd::Read;
+    }
+    if (FD_ISSET(native_fd, &write_fd_)) {
+      flags |= Fd::Write;
+    }
+    if (FD_ISSET(native_fd, &except_fd_)) {
+      flags |= Fd::Error;
+    }
+    if (flags != 0) {
+      it.fd_ref.update_flags_notify(flags);
+    }
+  }
+}
+
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/Select.h b/libs/tdlib/td/tdutils/td/utils/port/detail/Select.h
new file mode 100644
index 0000000000..17f2876f3a
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/Select.h
@@ -0,0 +1,59 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#ifdef TD_POLL_SELECT
+
+#include "td/utils/common.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/PollBase.h"
+
+#include <sys/select.h>
+
+namespace td {
+namespace detail {
+
+class Select final : public PollBase {
+ public:
+  Select() = default;
+  Select(const Select &) = delete;
+  Select &operator=(const Select &) = delete;
+  Select(Select &&) = delete;
+  Select &operator=(Select &&) = delete;
+  ~Select() override = default;
+
+  void init() override;
+
+  void clear() override;
+
+  void subscribe(const Fd &fd, Fd::Flags flags) override;
+
+  void unsubscribe(const Fd &fd) override;
+
+  void unsubscribe_before_close(const Fd &fd) override;
+
+  void run(int timeout_ms) override;
+
+ private:
+  struct FdInfo {
+    Fd fd_ref;
+    Fd::Flags flags;
+  };
+  vector<FdInfo> fds_;
+  fd_set all_fd_;
+  fd_set read_fd_;
+  fd_set write_fd_;
+  fd_set except_fd_;
+  int max_fd_;
+};
+
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/ThreadIdGuard.cpp b/libs/tdlib/td/tdutils/td/utils/port/detail/ThreadIdGuard.cpp
new file mode 100644
index 0000000000..d949945e1d
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/ThreadIdGuard.cpp
@@ -0,0 +1,52 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/detail/ThreadIdGuard.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/port/thread_local.h"
+
+#include <array>
+#include <mutex>
+
+namespace td {
+namespace detail {
+class ThreadIdManager {
+ public:
+  int32 register_thread() {
+    std::lock_guard<std::mutex> guard(mutex_);
+    for (size_t i = 0; i < is_id_used_.size(); i++) {
+      if (!is_id_used_[i]) {
+        is_id_used_[i] = true;
+        return static_cast<int32>(i + 1);
+      }
+    }
+    LOG(FATAL) << "Cannot create more than " << max_thread_count() << " threads";
+    return 0;
+  }
+  void unregister_thread(int32 thread_id) {
+    thread_id--;
+    std::lock_guard<std::mutex> guard(mutex_);
+    CHECK(is_id_used_.at(thread_id));
+    is_id_used_[thread_id] = false;
+  }
+
+ private:
+  std::mutex mutex_;
+  std::array<bool, max_thread_count()> is_id_used_{{false}};
+};
+static ThreadIdManager thread_id_manager;
+
+ThreadIdGuard::ThreadIdGuard() {
+  thread_id_ = thread_id_manager.register_thread();
+  set_thread_id(thread_id_);
+}
+ThreadIdGuard::~ThreadIdGuard() {
+  thread_id_manager.unregister_thread(thread_id_);
+  set_thread_id(0);
+}
+}  // namespace detail
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/ThreadIdGuard.h b/libs/tdlib/td/tdutils/td/utils/port/detail/ThreadIdGuard.h
new file mode 100644
index 0000000000..434bd5ac4d
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/ThreadIdGuard.h
@@ -0,0 +1,26 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+namespace td {
+namespace detail {
+class ThreadIdGuard {
+ public:
+  ThreadIdGuard();
+  ~ThreadIdGuard();
+  ThreadIdGuard(const ThreadIdGuard &) = delete;
+  ThreadIdGuard &operator=(const ThreadIdGuard &) = delete;
+  ThreadIdGuard(ThreadIdGuard &&) = delete;
+  ThreadIdGuard &operator=(ThreadIdGuard &&) = delete;
+
+ private:
+  int32 thread_id_;
+};
+}  // namespace detail
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/ThreadPthread.h b/libs/tdlib/td/tdutils/td/utils/port/detail/ThreadPthread.h
new file mode 100644
index 0000000000..e42efc3771
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/ThreadPthread.h
@@ -0,0 +1,90 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/utils/port/config.h"
+
+#ifdef TD_THREAD_PTHREAD
+
+#include "td/utils/common.h"
+#include "td/utils/invoke.h"
+#include "td/utils/MovableValue.h"
+#include "td/utils/port/detail/ThreadIdGuard.h"
+#include "td/utils/port/thread_local.h"
+
+#include <tuple>
+#include <type_traits>
+#include <utility>
+
+#include <pthread.h>
+#include <sched.h>
+
+namespace td {
+namespace detail {
+class ThreadPthread {
+ public:
+  ThreadPthread() = default;
+  ThreadPthread(const ThreadPthread &other) = delete;
+  ThreadPthread &operator=(const ThreadPthread &other) = delete;
+  ThreadPthread(ThreadPthread &&) = default;
+  ThreadPthread &operator=(ThreadPthread &&) = default;
+  template <class Function, class... Args>
+  explicit ThreadPthread(Function &&f, Args &&... args) {
+    func_ = std::make_unique<std::unique_ptr<Destructor>>(
+        create_destructor([args = std::make_tuple(decay_copy(std::forward<Function>(f)),
+                                                  decay_copy(std::forward<Args>(args))...)]() mutable {
+          invoke_tuple(std::move(args));
+          clear_thread_locals();
+        }));
+    pthread_create(&thread_, nullptr, run_thread, func_.get());
+    is_inited_ = true;
+  }
+  void join() {
+    if (is_inited_.get()) {
+      is_inited_ = false;
+      pthread_join(thread_, nullptr);
+    }
+  }
+  ~ThreadPthread() {
+    join();
+  }
+
+  static unsigned hardware_concurrency() {
+    return 8;
+  }
+
+  using id = pthread_t;
+
+ private:
+  MovableValue<bool> is_inited_;
+  pthread_t thread_;
+  std::unique_ptr<std::unique_ptr<Destructor>> func_;
+
+  template <class T>
+  std::decay_t<T> decay_copy(T &&v) {
+    return std::forward<T>(v);
+  }
+
+  static void *run_thread(void *ptr) {
+    ThreadIdGuard thread_id_guard;
+    auto func = static_cast<decltype(func_.get())>(ptr);
+    func->reset();
+    return nullptr;
+  }
+};
+
+namespace this_thread_pthread {
+inline void yield() {
+  sched_yield();
+}
+inline ThreadPthread::id get_id() {
+  return pthread_self();
+}
+}  // namespace this_thread_pthread
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/ThreadStl.h b/libs/tdlib/td/tdutils/td/utils/port/detail/ThreadStl.h
new file mode 100644
index 0000000000..64bf3213cf
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/ThreadStl.h
@@ -0,0 +1,64 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/utils/port/config.h"
+
+#ifdef TD_THREAD_STL
+
+#include "td/utils/common.h"
+#include "td/utils/invoke.h"
+#include "td/utils/port/detail/ThreadIdGuard.h"
+#include "td/utils/port/thread_local.h"
+
+#include <thread>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+
+namespace td {
+namespace detail {
+class ThreadStl {
+ public:
+  ThreadStl() = default;
+  ThreadStl(const ThreadStl &other) = delete;
+  ThreadStl &operator=(const ThreadStl &other) = delete;
+  ThreadStl(ThreadStl &&) = default;
+  ThreadStl &operator=(ThreadStl &&) = default;
+  ~ThreadStl() = default;
+  template <class Function, class... Args>
+  explicit ThreadStl(Function &&f, Args &&... args) {
+    thread_ = std::thread([args = std::make_tuple(decay_copy(std::forward<Function>(f)),
+                                                  decay_copy(std::forward<Args>(args))...)]() mutable {
+      ThreadIdGuard thread_id_guard;
+      invoke_tuple(std::move(args));
+      clear_thread_locals();
+    });
+  }
+
+  void join() {
+    thread_.join();
+  }
+
+  static unsigned hardware_concurrency() {
+    return std::thread::hardware_concurrency();
+  }
+
+  using id = std::thread::id;
+
+ private:
+  std::thread thread_;
+
+  template <class T>
+  std::decay_t<T> decay_copy(T &&v) {
+    return std::forward<T>(v);
+  }
+};
+namespace this_thread_stl = std::this_thread;
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/WineventPoll.cpp b/libs/tdlib/td/tdutils/td/utils/port/detail/WineventPoll.cpp
new file mode 100644
index 0000000000..8f443d29ab
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/WineventPoll.cpp
@@ -0,0 +1,97 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/detail/WineventPoll.h"
+
+char disable_linker_warning_about_empty_file_wineventpoll_cpp TD_UNUSED;
+
+#ifdef TD_POLL_WINEVENT
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/PollBase.h"
+#include "td/utils/port/sleep.h"
+#include "td/utils/Status.h"
+
+#include <utility>
+
+namespace td {
+namespace detail {
+
+void WineventPoll::init() {
+  clear();
+}
+
+void WineventPoll::clear() {
+  fds_.clear();
+}
+
+void WineventPoll::subscribe(const Fd &fd, Fd::Flags flags) {
+  for (auto &it : fds_) {
+    if (it.fd_ref.get_key() == fd.get_key()) {
+      it.flags = flags;
+      return;
+    }
+  }
+  fds_.push_back({fd.clone(), flags});
+}
+
+void WineventPoll::unsubscribe(const Fd &fd) {
+  for (auto it = fds_.begin(); it != fds_.end(); ++it) {
+    if (it->fd_ref.get_key() == fd.get_key()) {
+      std::swap(*it, fds_.back());
+      fds_.pop_back();
+      return;
+    }
+  }
+}
+
+void WineventPoll::unsubscribe_before_close(const Fd &fd) {
+  unsubscribe(fd);
+}
+
+void WineventPoll::run(int timeout_ms) {
+  vector<std::pair<size_t, Fd::Flag>> events_desc;
+  vector<HANDLE> events;
+  for (size_t i = 0; i < fds_.size(); i++) {
+    auto &fd_info = fds_[i];
+    if (fd_info.flags & Fd::Flag::Write) {
+      events_desc.emplace_back(i, Fd::Flag::Write);
+      events.push_back(fd_info.fd_ref.get_write_event());
+    }
+    if (fd_info.flags & Fd::Flag::Read) {
+      events_desc.emplace_back(i, Fd::Flag::Read);
+      events.push_back(fd_info.fd_ref.get_read_event());
+    }
+  }
+  if (events.empty()) {
+    usleep_for(timeout_ms * 1000);
+    return;
+  }
+
+  auto status = WaitForMultipleObjects(narrow_cast<DWORD>(events.size()), events.data(), false, timeout_ms);
+  if (status == WAIT_FAILED) {
+    auto error = OS_ERROR("WaitForMultipleObjects failed");
+    LOG(FATAL) << events.size() << " " << timeout_ms << " " << error;
+  }
+  for (size_t i = 0; i < events.size(); i++) {
+    if (WaitForSingleObject(events[i], 0) == WAIT_OBJECT_0) {
+      auto &fd = fds_[events_desc[i].first].fd_ref;
+      if (events_desc[i].second == Fd::Flag::Read) {
+        fd.on_read_event();
+      } else {
+        fd.on_write_event();
+      }
+    }
+  }
+}
+
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/detail/WineventPoll.h b/libs/tdlib/td/tdutils/td/utils/port/detail/WineventPoll.h
new file mode 100644
index 0000000000..ecc93f33fa
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/detail/WineventPoll.h
@@ -0,0 +1,52 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#ifdef TD_POLL_WINEVENT
+
+#include "td/utils/common.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/PollBase.h"
+
+namespace td {
+namespace detail {
+
+class WineventPoll final : public PollBase {
+ public:
+  WineventPoll() = default;
+  WineventPoll(const WineventPoll &) = delete;
+  WineventPoll &operator=(const WineventPoll &) = delete;
+  WineventPoll(WineventPoll &&) = delete;
+  WineventPoll &operator=(WineventPoll &&) = delete;
+  ~WineventPoll() override = default;
+
+  void init() override;
+
+  void clear() override;
+
+  void subscribe(const Fd &fd, Fd::Flags flags) override;
+
+  void unsubscribe(const Fd &fd) override;
+
+  void unsubscribe_before_close(const Fd &fd) override;
+
+  void run(int timeout_ms) override;
+
+ private:
+  struct FdInfo {
+    Fd fd_ref;
+    Fd::Flags flags;
+  };
+  vector<FdInfo> fds_;
+};
+
+}  // namespace detail
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/path.cpp b/libs/tdlib/td/tdutils/td/utils/port/path.cpp
new file mode 100644
index 0000000000..8b169fefa4
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/path.cpp
@@ -0,0 +1,383 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/path.h"
+
+#include "td/utils/port/Fd.h"
+
+#if TD_WINDOWS
+#include "td/utils/Random.h"
+#endif
+
+#if TD_PORT_POSIX
+
+#include <limits.h>
+#include <stdio.h>
+
+// We don't want warnings from system headers
+#if TD_GCC
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wconversion"
+#endif
+#include <sys/stat.h>
+#if TD_GCC
+#pragma GCC diagnostic pop
+#endif
+
+#include <sys/types.h>
+#include <unistd.h>
+
+#endif
+
+#include <cstdlib>
+
+namespace td {
+
+static string temporary_dir;
+
+Status set_temporary_dir(CSlice dir) {
+  string input_dir = dir.str();
+  if (!dir.empty() && dir.back() != TD_DIR_SLASH) {
+    input_dir += TD_DIR_SLASH;
+  }
+  TRY_STATUS(mkpath(input_dir, 0750));
+  TRY_RESULT(real_dir, realpath(input_dir));
+  temporary_dir = std::move(real_dir);
+  return Status::OK();
+}
+
+Status mkpath(CSlice path, int32 mode) {
+  Status first_error = Status::OK();
+  Status last_error = Status::OK();
+  for (size_t i = 1; i < path.size(); i++) {
+    if (path[i] == TD_DIR_SLASH) {
+      last_error = mkdir(path.substr(0, i).str(), mode);
+      if (last_error.is_error() && first_error.is_ok()) {
+        first_error = last_error.clone();
+      }
+    }
+  }
+  if (last_error.is_error()) {
+    return first_error;
+  }
+  return Status::OK();
+}
+
+#if TD_PORT_POSIX
+
+Status mkdir(CSlice dir, int32 mode) {
+  int mkdir_res = skip_eintr([&] { return ::mkdir(dir.c_str(), static_cast<mode_t>(mode)); });
+  if (mkdir_res == 0) {
+    return Status::OK();
+  }
+  auto mkdir_errno = errno;
+  if (mkdir_errno == EEXIST) {
+    // TODO check that it is a directory
+    return Status::OK();
+  }
+  return Status::PosixError(mkdir_errno, PSLICE() << "Can't create directory \"" << dir << '"');
+}
+
+Status rename(CSlice from, CSlice to) {
+  int rename_res = skip_eintr([&] { return ::rename(from.c_str(), to.c_str()); });
+  if (rename_res < 0) {
+    return OS_ERROR(PSLICE() << "Can't rename \"" << from << "\" to \"" << to << '\"');
+  }
+  return Status::OK();
+}
+
+Result<string> realpath(CSlice slice, bool ignore_access_denied) {
+  char full_path[PATH_MAX + 1];
+  string res;
+  char *err = skip_eintr_cstr([&] { return ::realpath(slice.c_str(), full_path); });
+  if (err != full_path) {
+    if (ignore_access_denied && errno == EACCES) {
+      res = slice.str();
+    } else {
+      return OS_ERROR(PSLICE() << "Realpath failed for \"" << slice << '"');
+    }
+  } else {
+    res = full_path;
+  }
+  if (res.empty()) {
+    return Status::Error("Empty path");
+  }
+  if (!slice.empty() && slice.end()[-1] == TD_DIR_SLASH) {
+    if (res.back() != TD_DIR_SLASH) {
+      res += TD_DIR_SLASH;
+    }
+  }
+  return res;
+}
+
+Status chdir(CSlice dir) {
+  int chdir_res = skip_eintr([&] { return ::chdir(dir.c_str()); });
+  if (chdir_res) {
+    return OS_ERROR(PSLICE() << "Can't change directory to \"" << dir << '"');
+  }
+  return Status::OK();
+}
+
+Status rmdir(CSlice dir) {
+  int rmdir_res = skip_eintr([&] { return ::rmdir(dir.c_str()); });
+  if (rmdir_res) {
+    return OS_ERROR(PSLICE() << "Can't delete directory \"" << dir << '"');
+  }
+  return Status::OK();
+}
+
+Status unlink(CSlice path) {
+  int unlink_res = skip_eintr([&] { return ::unlink(path.c_str()); });
+  if (unlink_res) {
+    return OS_ERROR(PSLICE() << "Can't unlink \"" << path << '"');
+  }
+  return Status::OK();
+}
+
+CSlice get_temporary_dir() {
+  static bool is_inited = [] {
+    if (temporary_dir.empty()) {
+      const char *s = std::getenv("TMPDIR");
+      if (s != nullptr && s[0] != '\0') {
+        temporary_dir = s;
+      } else if (P_tmpdir != nullptr && P_tmpdir[0] != '\0') {
+        temporary_dir = P_tmpdir;
+      } else {
+        return false;
+      }
+    }
+    if (temporary_dir.size() > 1 && temporary_dir.back() == TD_DIR_SLASH) {
+      temporary_dir.pop_back();
+    }
+    return true;
+  }();
+  LOG_IF(FATAL, !is_inited) << "Can't find temporary directory";
+  return temporary_dir;
+}
+
+Result<std::pair<FileFd, string>> mkstemp(CSlice dir) {
+  if (dir.empty()) {
+    dir = get_temporary_dir();
+    if (dir.empty()) {
+      return Status::Error("Can't find temporary directory");
+    }
+  }
+
+  TRY_RESULT(dir_real, realpath(dir));
+  CHECK(!dir_real.empty());
+
+  string file_pattern;
+  file_pattern.reserve(dir_real.size() + 14);
+  file_pattern = dir_real;
+  if (file_pattern.back() != TD_DIR_SLASH) {
+    file_pattern += TD_DIR_SLASH;
+  }
+  file_pattern += "tmpXXXXXXXXXX";
+
+  int fd = skip_eintr([&] { return ::mkstemp(&file_pattern[0]); });
+  if (fd == -1) {
+    return OS_ERROR(PSLICE() << "Can't create temporary file \"" << file_pattern << '"');
+  }
+  if (close(fd)) {
+    return OS_ERROR(PSLICE() << "Can't close temporary file \"" << file_pattern << '"');
+  }
+  // TODO create file from fd
+  TRY_RESULT(file, FileFd::open(file_pattern, FileFd::Write | FileFd::Truncate | FileFd::Append));
+  return std::make_pair(std::move(file), std::move(file_pattern));
+}
+
+Result<string> mkdtemp(CSlice dir, Slice prefix) {
+  if (dir.empty()) {
+    dir = get_temporary_dir();
+    if (dir.empty()) {
+      return Status::Error("Can't find temporary directory");
+    }
+  }
+
+  TRY_RESULT(dir_real, realpath(dir));
+  CHECK(!dir_real.empty());
+
+  string dir_pattern;
+  dir_pattern.reserve(dir_real.size() + prefix.size() + 7);
+  dir_pattern = dir_real;
+  if (dir_pattern.back() != TD_DIR_SLASH) {
+    dir_pattern += TD_DIR_SLASH;
+  }
+  dir_pattern.append(prefix.begin(), prefix.size());
+  dir_pattern += "XXXXXX";
+
+  char *result = skip_eintr_cstr([&] { return ::mkdtemp(&dir_pattern[0]); });
+  if (result == nullptr) {
+    return OS_ERROR(PSLICE() << "Can't create temporary directory \"" << dir_pattern << '"');
+  }
+  return result;
+}
+
+#endif
+
+#if TD_PORT_WINDOWS
+
+Status mkdir(CSlice dir, int32 mode) {
+  TRY_RESULT(wdir, to_wstring(dir));
+  auto status = CreateDirectoryW(wdir.c_str(), nullptr);
+  if (status == 0 && GetLastError() != ERROR_ALREADY_EXISTS) {
+    return OS_ERROR(PSLICE() << "Can't create directory \"" << dir << '"');
+  }
+  return Status::OK();
+}
+
+Status rename(CSlice from, CSlice to) {
+  TRY_RESULT(wfrom, to_wstring(from));
+  TRY_RESULT(wto, to_wstring(to));
+  auto status = MoveFileExW(wfrom.c_str(), wto.c_str(), MOVEFILE_REPLACE_EXISTING);
+  if (status == 0) {
+    return OS_ERROR(PSLICE() << "Can't rename \"" << from << "\" to \"" << to << '\"');
+  }
+  return Status::OK();
+}
+
+Result<string> realpath(CSlice slice, bool ignore_access_denied) {
+  wchar_t buf[MAX_PATH + 1];
+  TRY_RESULT(wslice, to_wstring(slice));
+  auto status = GetFullPathNameW(wslice.c_str(), MAX_PATH, buf, nullptr);
+  string res;
+  if (status == 0) {
+    if (ignore_access_denied && errno == ERROR_ACCESS_DENIED) {
+      res = slice.str();
+    } else {
+      return OS_ERROR(PSLICE() << "GetFullPathNameW failed for \"" << slice << '"');
+    }
+  } else {
+    TRY_RESULT(t_res, from_wstring(buf));
+    res = std::move(t_res);
+  }
+  if (res.empty()) {
+    return Status::Error("Empty path");
+  }
+  if (!slice.empty() && slice.end()[-1] == TD_DIR_SLASH) {
+    if (res.back() != TD_DIR_SLASH) {
+      res += TD_DIR_SLASH;
+    }
+  }
+  return res;
+}
+
+Status chdir(CSlice dir) {
+  TRY_RESULT(wdir, to_wstring(dir));
+  auto res = SetCurrentDirectoryW(wdir.c_str());
+  if (res == 0) {
+    return OS_ERROR(PSLICE() << "Can't change directory to \"" << dir << '"');
+  }
+  return Status::OK();
+}
+
+Status rmdir(CSlice dir) {
+  TRY_RESULT(wdir, to_wstring(dir));
+  int status = RemoveDirectoryW(wdir.c_str());
+  if (!status) {
+    return OS_ERROR(PSLICE() << "Can't delete directory \"" << dir << '"');
+  }
+  return Status::OK();
+}
+
+Status unlink(CSlice path) {
+  TRY_RESULT(wpath, to_wstring(path));
+  int status = DeleteFileW(wpath.c_str());
+  if (!status) {
+    return OS_ERROR(PSLICE() << "Can't unlink \"" << path << '"');
+  }
+  return Status::OK();
+}
+
+CSlice get_temporary_dir() {
+  static bool is_inited = [] {
+    if (temporary_dir.empty()) {
+      wchar_t buf[MAX_PATH + 1];
+      if (GetTempPathW(MAX_PATH, buf) == 0) {
+        auto error = OS_ERROR("GetTempPathW failed");
+        LOG(FATAL) << error;
+      }
+      auto rs = from_wstring(buf);
+      LOG_IF(FATAL, rs.is_error()) << "GetTempPathW failed: " << rs.error();
+      temporary_dir = rs.ok();
+    }
+    if (temporary_dir.size() > 1 && temporary_dir.back() == TD_DIR_SLASH) {
+      temporary_dir.pop_back();
+    }
+    return true;
+  }();
+  LOG_IF(FATAL, !is_inited) << "Can't find temporary directory";
+  return temporary_dir;
+}
+
+Result<string> mkdtemp(CSlice dir, Slice prefix) {
+  if (dir.empty()) {
+    dir = get_temporary_dir();
+    if (dir.empty()) {
+      return Status::Error("Can't find temporary directory");
+    }
+  }
+
+  TRY_RESULT(dir_real, realpath(dir));
+  CHECK(!dir_real.empty());
+
+  string dir_pattern;
+  dir_pattern.reserve(dir_real.size() + prefix.size() + 7);
+  dir_pattern = dir_real;
+  if (dir_pattern.back() != TD_DIR_SLASH) {
+    dir_pattern += TD_DIR_SLASH;
+  }
+  dir_pattern.append(prefix.begin(), prefix.size());
+
+  for (auto it = 0; it < 20; it++) {
+    auto path = dir_pattern;
+    for (int i = 0; i < 6 + it / 5; i++) {
+      path += static_cast<char>(Random::fast('a', 'z'));
+    }
+    auto status = mkdir(path);
+    if (status.is_ok()) {
+      return path;
+    }
+  }
+  return Status::Error(PSLICE() << "Can't create temporary directory \"" << dir_pattern << '"');
+}
+
+Result<std::pair<FileFd, string>> mkstemp(CSlice dir) {
+  if (dir.empty()) {
+    dir = get_temporary_dir();
+    if (dir.empty()) {
+      return Status::Error("Can't find temporary directory");
+    }
+  }
+
+  TRY_RESULT(dir_real, realpath(dir));
+  CHECK(!dir_real.empty());
+
+  string file_pattern;
+  file_pattern.reserve(dir_real.size() + 14);
+  file_pattern = dir_real;
+  if (file_pattern.back() != TD_DIR_SLASH) {
+    file_pattern += TD_DIR_SLASH;
+  }
+  file_pattern += "tmp";
+
+  for (auto it = 0; it < 20; it++) {
+    auto path = file_pattern;
+    for (int i = 0; i < 6 + it / 5; i++) {
+      path += static_cast<char>(Random::fast('a', 'z'));
+    }
+    auto r_file = FileFd::open(path, FileFd::Write | FileFd::Read | FileFd::CreateNew);
+    if (r_file.is_ok()) {
+      return std::make_pair(r_file.move_as_ok(), path);
+    }
+  }
+
+  return Status::Error(PSLICE() << "Can't create temporary file \"" << file_pattern << '"');
+}
+
+#endif
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/path.h b/libs/tdlib/td/tdutils/td/utils/port/path.h
new file mode 100644
index 0000000000..47b7d3a350
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/path.h
@@ -0,0 +1,225 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/ScopeGuard.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <utility>
+
+#if TD_PORT_POSIX
+#include <dirent.h>
+#include <sys/types.h>
+#endif
+
+#if TD_DARWIN
+#include <sys/syslimits.h>
+#endif
+
+#if TD_PORT_WINDOWS
+#include "td/utils/port/wstring_convert.h"
+
+#include <string>
+#endif
+
+namespace td {
+
+Status mkdir(CSlice dir, int32 mode = 0700) TD_WARN_UNUSED_RESULT;
+Status mkpath(CSlice path, int32 mode = 0700) TD_WARN_UNUSED_RESULT;
+Status rename(CSlice from, CSlice to) TD_WARN_UNUSED_RESULT;
+Result<string> realpath(CSlice slice, bool ignore_access_denied = false) TD_WARN_UNUSED_RESULT;
+Status chdir(CSlice dir) TD_WARN_UNUSED_RESULT;
+Status rmdir(CSlice dir) TD_WARN_UNUSED_RESULT;
+Status unlink(CSlice path) TD_WARN_UNUSED_RESULT;
+Status set_temporary_dir(CSlice dir) TD_WARN_UNUSED_RESULT;
+CSlice get_temporary_dir();
+Result<std::pair<FileFd, string>> mkstemp(CSlice dir) TD_WARN_UNUSED_RESULT;
+Result<string> mkdtemp(CSlice dir, Slice prefix) TD_WARN_UNUSED_RESULT;
+
+template <class Func>
+Status walk_path(CSlice path, Func &func) TD_WARN_UNUSED_RESULT;
+
+#if TD_PORT_POSIX
+
+// TODO move details somewhere else
+namespace detail {
+template <class Func>
+Status walk_path_dir(string &path, FileFd fd, Func &&func) TD_WARN_UNUSED_RESULT;
+template <class Func>
+Status walk_path_dir(string &path, Func &&func) TD_WARN_UNUSED_RESULT;
+template <class Func>
+Status walk_path_file(string &path, Func &&func) TD_WARN_UNUSED_RESULT;
+template <class Func>
+Status walk_path(string &path, Func &&func) TD_WARN_UNUSED_RESULT;
+
+template <class Func>
+Status walk_path_subdir(string &path, DIR *dir, Func &&func) {
+  while (true) {
+    errno = 0;
+    auto *entry = readdir(dir);
+    auto readdir_errno = errno;
+    if (readdir_errno) {
+      return Status::PosixError(readdir_errno, "readdir");
+    }
+    if (entry == nullptr) {
+      return Status::OK();
+    }
+    Slice name = Slice(&*entry->d_name);
+    if (name == "." || name == "..") {
+      continue;
+    }
+    auto size = path.size();
+    if (path.back() != TD_DIR_SLASH) {
+      path += TD_DIR_SLASH;
+    }
+    path.append(name.begin(), name.size());
+    SCOPE_EXIT {
+      path.resize(size);
+    };
+    Status status;
+#ifdef DT_DIR
+    if (entry->d_type == DT_UNKNOWN) {
+      status = walk_path(path, std::forward<Func>(func));
+    } else if (entry->d_type == DT_DIR) {
+      status = walk_path_dir(path, std::forward<Func>(func));
+    } else if (entry->d_type == DT_REG) {
+      status = walk_path_file(path, std::forward<Func>(func));
+    }
+#else
+#warning "Slow walk_path"
+    status = walk_path(path, std::forward<Func>(func));
+#endif
+    if (status.is_error()) {
+      return status;
+    }
+  }
+}
+
+template <class Func>
+Status walk_path_dir(string &path, DIR *subdir, Func &&func) {
+  SCOPE_EXIT {
+    closedir(subdir);
+  };
+  TRY_STATUS(walk_path_subdir(path, subdir, std::forward<Func>(func)));
+  std::forward<Func>(func)(path, true);
+  return Status::OK();
+}
+
+template <class Func>
+Status walk_path_dir(string &path, FileFd fd, Func &&func) {
+  auto *subdir = fdopendir(fd.get_fd().move_as_native_fd());
+  if (subdir == nullptr) {
+    auto error = OS_ERROR("fdopendir");
+    fd.close();
+    return error;
+  }
+  return walk_path_dir(path, subdir, std::forward<Func>(func));
+}
+
+template <class Func>
+Status walk_path_dir(string &path, Func &&func) {
+  auto *subdir = opendir(path.c_str());
+  if (subdir == nullptr) {
+    return OS_ERROR(PSLICE() << tag("opendir", path));
+  }
+  return walk_path_dir(path, subdir, std::forward<Func>(func));
+}
+
+template <class Func>
+Status walk_path_file(string &path, Func &&func) {
+  std::forward<Func>(func)(path, false);
+  return Status::OK();
+}
+
+template <class Func>
+Status walk_path(string &path, Func &&func) {
+  TRY_RESULT(fd, FileFd::open(path, FileFd::Read));
+  auto stat = fd.stat();
+  bool is_dir = stat.is_dir_;
+  bool is_reg = stat.is_reg_;
+  if (is_dir) {
+    return walk_path_dir(path, std::move(fd), std::forward<Func>(func));
+  }
+
+  fd.close();
+  if (is_reg) {
+    return walk_path_file(path, std::forward<Func>(func));
+  }
+
+  return Status::OK();
+}
+}  // namespace detail
+
+template <class Func>
+Status walk_path(CSlice path, Func &&func) {
+  string curr_path;
+  curr_path.reserve(PATH_MAX + 10);
+  curr_path = path.c_str();
+  return detail::walk_path(curr_path, std::forward<Func>(func));
+}
+
+#endif
+
+#if TD_PORT_WINDOWS
+
+namespace detail {
+template <class Func>
+Status walk_path_dir(const std::wstring &dir_name, Func &&func) {
+  std::wstring name = dir_name + L"\\*";
+
+  WIN32_FIND_DATA file_data;
+  auto handle = FindFirstFileExW(name.c_str(), FindExInfoStandard, &file_data, FindExSearchNameMatch, nullptr, 0);
+  if (handle == INVALID_HANDLE_VALUE) {
+    return OS_ERROR(PSLICE() << "FindFirstFileEx" << tag("name", from_wstring(name).ok()));
+  }
+
+  SCOPE_EXIT {
+    FindClose(handle);
+  };
+  while (true) {
+    auto full_name = dir_name + L"\\" + file_data.cFileName;
+    TRY_RESULT(entry_name, from_wstring(full_name));
+    if (file_data.cFileName[0] != '.') {
+      if ((file_data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0) {
+        TRY_STATUS(walk_path_dir(full_name, func));
+        func(entry_name, true);
+      } else {
+        func(entry_name, false);
+      }
+    }
+    auto status = FindNextFileW(handle, &file_data);
+    if (status == 0) {
+      auto last_error = GetLastError();
+      if (last_error == ERROR_NO_MORE_FILES) {
+        return Status::OK();
+      }
+      return OS_ERROR("FindNextFileW");
+    }
+  }
+}
+}  // namespace detail
+
+template <class Func>
+Status walk_path(CSlice path, Func &&func) {
+  Slice path_slice = path;
+  while (!path_slice.empty() && (path_slice.back() == '/' || path_slice.back() == '\\')) {
+    path_slice.remove_suffix(1);
+  }
+  TRY_RESULT(wpath, to_wstring(path_slice));
+  return detail::walk_path_dir(wpath.c_str(), func);
+}
+
+#endif
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/platform.h b/libs/tdlib/td/tdutils/td/utils/port/platform.h
new file mode 100644
index 0000000000..a1c3776a40
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/platform.h
@@ -0,0 +1,106 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+// clang-format off
+
+/*** Platform macros ***/
+#if defined(_WIN32)
+  #if defined(__cplusplus_winrt)
+    #define TD_WINRT 1
+  #endif
+  #if defined(__cplusplus_cli)
+    #define TD_CLI 1
+  #endif
+  #define TD_WINDOWS 1
+#elif defined(__APPLE__)
+  #include "TargetConditionals.h"
+  #if TARGET_OS_IPHONE
+    // iOS/Apple Watch OS/Apple TV OS
+    #if TARGET_OS_IOS
+      #define TD_DARWIN_IOS 1
+    #elif TARGET_OS_TV
+      #define TD_DARWIN_TV_OS 1
+    #elif TARGET_OS_WATCH
+      #define TD_DARWIN_WATCH_OS 1
+    #else
+      #warning "Probably unsupported Apple iPhone platform. Feel free to try to compile"
+    #endif
+  #elif TARGET_OS_MAC
+    // Other kinds of Mac OS
+    #define TD_DARWIN_MAC 1
+  #else
+    #warning "Probably unsupported Apple platform. Feel free to try to compile"
+  #endif
+  #define TD_DARWIN 1
+#elif defined(ANDROID) || defined(__ANDROID__)
+  #define TD_ANDROID 1
+#elif defined(TIZEN_DEPRECATION)
+  #define TD_TIZEN 1
+#elif defined(__linux__)
+  #define TD_LINUX 1
+#elif defined(__CYGWIN__)
+  #define TD_CYGWIN 1
+#elif defined(__EMSCRIPTEN__)
+  #define TD_EMSCRIPTEN 1
+#elif defined(__unix__)  // all unices not caught above
+  #warning "Probably unsupported Unix platform. Feel free to try to compile"
+  #define TD_CYGWIN 1
+#else
+  #error "Probably unsupported platform. Feel free to remove the error and try to recompile"
+#endif
+
+#if defined(__ICC) || defined(__INTEL_COMPILER)
+  #define TD_INTEL 1
+#elif defined(__clang__)
+  #define TD_CLANG 1
+#elif defined(__GNUC__) || defined(__GNUG__)
+  #define TD_GCC 1
+#elif defined(_MSC_VER)
+  #define TD_MSVC 1
+#else
+  #warning "Probably unsupported compiler. Feel free to try to compile"
+#endif
+
+#if TD_GCC || TD_CLANG || TD_INTEL
+  #define TD_WARN_UNUSED_RESULT __attribute__((warn_unused_result))
+  #define TD_ATTRIBUTE_FORMAT_PRINTF(from, to) __attribute__((format(printf, from, to)))
+#else
+  #define TD_WARN_UNUSED_RESULT
+  #define TD_ATTRIBUTE_FORMAT_PRINTF(from, to)
+#endif
+
+#if TD_MSVC
+  #define TD_UNUSED __pragma(warning(suppress : 4100))
+#elif TD_CLANG || TD_GCC || TD_INTEL
+  #define TD_UNUSED __attribute__((unused))
+#else
+  #define TD_UNUSED
+#endif
+
+#define TD_HAVE_ATOMIC_SHARED_PTR 1
+
+// No atomic operations on std::shared_ptr in libstdc++ before 5.0
+// see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57250
+#ifdef __GLIBCXX__
+  #undef TD_HAVE_ATOMIC_SHARED_PTR
+#endif
+
+// Also no atomic operations on std::shared_ptr when clang __has_feature(cxx_atomic) is defined and zero
+#if defined(__has_feature)
+  #if !__has_feature(cxx_atomic)
+    #undef TD_HAVE_ATOMIC_SHARED_PTR
+  #endif
+#endif
+
+#ifdef TD_HAVE_ATOMIC_SHARED_PTR // unfortunately we can't check for __GLIBCXX__ here, it is not defined yet
+  #undef TD_HAVE_ATOMIC_SHARED_PTR
+#endif
+
+#define TD_CONCURRENCY_PAD 128
+
+// clang-format on
diff --git a/libs/tdlib/td/tdutils/td/utils/port/signals.cpp b/libs/tdlib/td/tdutils/td/utils/port/signals.cpp
new file mode 100644
index 0000000000..8627474d63
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/signals.cpp
@@ -0,0 +1,298 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/signals.h"
+
+#include "td/utils/port/config.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+
+#if TD_PORT_POSIX
+#include <signal.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#endif
+#if TD_PORT_WINDOWS
+#include <csignal>
+#endif
+
+#include <cerrno>
+#include <cstdint>
+#include <cstring>
+#include <ctime>
+#include <limits>
+
+namespace td {
+
+#if TD_PORT_POSIX && !TD_DARWIN_TV_OS && !TD_DARWIN_WATCH_OS
+static Status protect_memory(void *addr, size_t len) {
+  if (mprotect(addr, len, PROT_NONE) != 0) {
+    return OS_ERROR("mprotect failed");
+  }
+  return Status::OK();
+}
+#endif
+
+Status setup_signals_alt_stack() {
+#if TD_PORT_POSIX && !TD_DARWIN_TV_OS && !TD_DARWIN_WATCH_OS
+  auto page_size = getpagesize();
+  auto stack_size = (MINSIGSTKSZ + 16 * page_size - 1) / page_size * page_size;
+
+  void *stack = mmap(nullptr, stack_size + 2 * page_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
+  if (stack == MAP_FAILED) {
+    return OS_ERROR("Mmap failed");
+  }
+
+  TRY_STATUS(protect_memory(stack, page_size));
+  TRY_STATUS(protect_memory(static_cast<char *>(stack) + stack_size + page_size, page_size));
+
+  stack_t signal_stack;
+  signal_stack.ss_sp = static_cast<char *>(stack) + page_size;
+  signal_stack.ss_size = stack_size;
+  signal_stack.ss_flags = 0;
+
+  if (sigaltstack(&signal_stack, nullptr) != 0) {
+    return OS_ERROR("sigaltstack failed");
+  }
+#endif
+  return Status::OK();
+}
+
+#if TD_PORT_POSIX
+template <class F>
+static Status set_signal_handler_impl(vector<int> signals, F func, bool is_extended = false) {
+  struct sigaction act;
+  std::memset(&act, '\0', sizeof(act));
+  if (is_extended) {  // TODO if constexpr, remove useless reinterpret_cast
+    act.sa_handler = reinterpret_cast<decltype(act.sa_handler)>(func);
+  } else {
+    act.sa_sigaction = reinterpret_cast<decltype(act.sa_sigaction)>(func);
+  }
+  sigemptyset(&act.sa_mask);
+  for (auto signal : signals) {
+    sigaddset(&act.sa_mask, signal);
+  }
+  act.sa_flags = SA_RESTART | SA_ONSTACK;
+  if (is_extended) {
+    act.sa_flags |= SA_SIGINFO;
+  }
+
+  for (auto signal : signals) {
+    if (sigaction(signal, &act, nullptr) != 0) {
+      return OS_ERROR("sigaction failed");
+    }
+  }
+  return Status::OK();
+}
+
+static vector<int> get_native_signals(SignalType type) {
+  switch (type) {
+    case SignalType::Abort:
+      return {SIGABRT, SIGXCPU, SIGXFSZ};
+    case SignalType::Error:
+      return {SIGILL, SIGFPE, SIGBUS, SIGSEGV, SIGSYS};
+    case SignalType::Quit:
+      return {SIGINT, SIGTERM, SIGQUIT};
+    case SignalType::Pipe:
+      return {SIGPIPE};
+    case SignalType::HangUp:
+      return {SIGHUP};
+    case SignalType::User:
+      return {SIGUSR1, SIGUSR2};
+    case SignalType::Other:
+      return {SIGTRAP, SIGALRM, SIGVTALRM, SIGPROF, SIGTSTP, SIGTTIN, SIGTTOU};
+    default:
+      return {};
+  }
+}
+#endif
+#if TD_PORT_WINDOWS
+static Status set_signal_handler_impl(vector<int> signals, void (*func)(int sig), bool /*unused*/ = true) {
+  for (auto signal : signals) {
+    if (std::signal(signal, func) == SIG_ERR) {
+      return Status::Error("Failed to set signal handler");
+    }
+  }
+  return Status::OK();
+}
+
+static vector<int> get_native_signals(SignalType type) {
+  switch (type) {
+    case SignalType::Abort:
+      return {SIGABRT};
+    case SignalType::Error:
+      return {SIGILL, SIGFPE, SIGSEGV};
+    case SignalType::Quit:
+      return {SIGINT, SIGTERM};
+    case SignalType::Pipe:
+      return {};
+    case SignalType::HangUp:
+      return {};
+    case SignalType::User:
+      return {};
+    case SignalType::Other:
+      return {};
+    default:
+      return {};
+  }
+}
+#endif
+
+Status set_signal_handler(SignalType type, void (*func)(int)) {
+  return set_signal_handler_impl(get_native_signals(type), func == nullptr ? SIG_DFL : func);
+}
+
+using extended_signal_handler = void (*)(int sig, void *addr);
+static extended_signal_handler extended_signal_handlers[NSIG] = {};
+
+#if TD_PORT_POSIX
+static void siginfo_handler(int signum, siginfo_t *info, void *data) {
+  auto handler = extended_signal_handlers[signum];
+  handler(signum, info->si_addr);
+}
+#elif TD_PORT_WINDOWS
+static void siginfo_handler(int signum) {
+  auto handler = extended_signal_handlers[signum];
+  handler(signum, nullptr);
+}
+#endif
+
+Status set_extended_signal_handler(SignalType type, extended_signal_handler func) {
+  CHECK(func != nullptr);
+  auto signals = get_native_signals(type);
+  for (auto signal : signals) {
+    if (0 <= signal && signal < NSIG) {
+      extended_signal_handlers[signal] = func;
+    } else {
+      UNREACHABLE();
+    }
+  }
+  return set_signal_handler_impl(std::move(signals), siginfo_handler, true);
+}
+
+Status set_runtime_signal_handler(int runtime_signal_number, void (*func)(int)) {
+#ifdef SIGRTMIN
+  CHECK(SIGRTMIN + runtime_signal_number <= SIGRTMAX);
+  return set_signal_handler_impl({SIGRTMIN + runtime_signal_number}, func == nullptr ? SIG_DFL : func);
+#else
+  return Status::OK();
+#endif
+}
+
+Status ignore_signal(SignalType type) {
+  return set_signal_handler_impl(get_native_signals(type), SIG_IGN);
+}
+
+static void signal_safe_append_int(char **s, Slice name, int number) {
+  if (number < 0) {
+    number = std::numeric_limits<int>::max();
+  }
+
+  *--*s = ' ';
+  *--*s = ']';
+
+  do {
+    *--*s = static_cast<char>(number % 10 + '0');
+    number /= 10;
+  } while (number > 0);
+
+  *--*s = ' ';
+
+  for (auto pos = static_cast<int>(name.size()) - 1; pos >= 0; pos--) {
+    *--*s = name[pos];
+  }
+
+  *--*s = '[';
+}
+
+static void signal_safe_write_data(Slice data) {
+#if TD_PORT_POSIX
+  while (!data.empty()) {
+    auto res = write(2, data.begin(), data.size());
+    if (res < 0 && errno == EINTR) {
+      continue;
+    }
+    if (res <= 0) {
+      break;
+    }
+
+    if (res > 0) {
+      data.remove_prefix(res);
+    }
+  }
+#elif TD_PORT_WINDOWS
+#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP | WINAPI_PARTITION_SYSTEM)
+  HANDLE stderr_handle = GetStdHandle(STD_ERROR_HANDLE);
+  DWORD bytes_written;
+  WriteFile(stderr_handle, data.data(), static_cast<DWORD>(data.size()), &bytes_written, nullptr);
+#else
+// there is no stderr
+#endif
+#endif
+}
+
+static int get_process_id() {
+#if TD_PORT_POSIX
+  return getpid();
+#elif TD_PORT_WINDOWS
+  return GetCurrentProcessId();
+#endif
+}
+
+void signal_safe_write(Slice data, bool add_header) {
+  auto old_errno = errno;
+
+  if (add_header) {
+    constexpr size_t HEADER_BUF_SIZE = 100;
+    char header[HEADER_BUF_SIZE];
+    char *header_end = header + HEADER_BUF_SIZE;
+    char *header_begin = header_end;
+
+    signal_safe_append_int(&header_begin, "time", static_cast<int>(std::time(nullptr)));
+    signal_safe_append_int(&header_begin, "pid", get_process_id());
+
+    signal_safe_write_data(Slice(header_begin, header_end));
+  }
+
+  signal_safe_write_data(data);
+
+  errno = old_errno;
+}
+
+void signal_safe_write_signal_number(int sig, bool add_header) {
+  char buf[100];
+  char *end = buf + sizeof(buf);
+  char *ptr = end;
+  *--ptr = '\n';
+  do {
+    *--ptr = static_cast<char>(sig % 10 + '0');
+    sig /= 10;
+  } while (sig != 0);
+
+  ptr -= 8;
+  std::memcpy(ptr, "Signal: ", 8);
+  signal_safe_write(Slice(ptr, end), add_header);
+}
+
+void signal_safe_write_pointer(void *p, bool add_header) {
+  std::uintptr_t addr = reinterpret_cast<std::uintptr_t>(p);
+  char buf[100];
+  char *end = buf + sizeof(buf);
+  char *ptr = end;
+  *--ptr = '\n';
+  do {
+    *--ptr = td::format::hex_digit(addr % 16);
+    addr /= 16;
+  } while (addr != 0);
+  *--ptr = 'x';
+  *--ptr = '0';
+  ptr -= 9;
+  std::memcpy(ptr, "Address: ", 9);
+  signal_safe_write(Slice(ptr, end), add_header);
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/signals.h b/libs/tdlib/td/tdutils/td/utils/port/signals.h
new file mode 100644
index 0000000000..1f6ed24732
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/signals.h
@@ -0,0 +1,34 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+namespace td {
+
+Status setup_signals_alt_stack() TD_WARN_UNUSED_RESULT;
+
+enum class SignalType { Abort, Error, Quit, Pipe, HangUp, User, Other };
+
+Status set_signal_handler(SignalType type, void (*func)(int sig)) TD_WARN_UNUSED_RESULT;
+
+Status set_extended_signal_handler(SignalType type, void (*func)(int sig, void *addr)) TD_WARN_UNUSED_RESULT;
+
+Status set_runtime_signal_handler(int runtime_signal_number, void (*func)(int sig)) TD_WARN_UNUSED_RESULT;
+
+Status ignore_signal(SignalType type) TD_WARN_UNUSED_RESULT;
+
+// writes data to the standard error stream in a signal-safe way
+void signal_safe_write(Slice data, bool add_header = true);
+
+void signal_safe_write_signal_number(int sig, bool add_header = true);
+
+void signal_safe_write_pointer(void *p, bool add_header = true);
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/sleep.cpp b/libs/tdlib/td/tdutils/td/utils/port/sleep.cpp
new file mode 100644
index 0000000000..4f02f69dfb
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/sleep.cpp
@@ -0,0 +1,37 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/sleep.h"
+
+#include "td/utils/port/config.h"
+
+#if TD_PORT_POSIX
+#if _POSIX_C_SOURCE >= 199309L
+#include <time.h>
+#else
+#include <unistd.h>
+#endif
+#endif
+
+namespace td {
+
+void usleep_for(int32 microseconds) {
+#if TD_PORT_WINDOWS
+  int32 milliseconds = microseconds / 1000 + (microseconds % 1000 ? 1 : 0);
+  Sleep(milliseconds);
+#else
+#if _POSIX_C_SOURCE >= 199309L
+  timespec ts;
+  ts.tv_sec = microseconds / 1000000;
+  ts.tv_nsec = (microseconds % 1000000) * 1000;
+  nanosleep(&ts, nullptr);
+#else
+  usleep(microseconds);
+#endif
+#endif
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/sleep.h b/libs/tdlib/td/tdutils/td/utils/port/sleep.h
new file mode 100644
index 0000000000..56cd9f7bcd
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/sleep.h
@@ -0,0 +1,15 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+namespace td {
+
+void usleep_for(int32 microseconds);
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/thread.h b/libs/tdlib/td/tdutils/td/utils/port/thread.h
new file mode 100644
index 0000000000..3034e456e8
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/thread.h
@@ -0,0 +1,34 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#include "td/utils/port/detail/ThreadPthread.h"
+#include "td/utils/port/detail/ThreadStl.h"
+
+namespace td {
+
+// clang-format off
+
+#if TD_THREAD_PTHREAD
+  using thread = detail::ThreadPthread;
+  namespace this_thread = detail::this_thread_pthread;
+#elif TD_THREAD_STL
+  using thread = detail::ThreadStl;
+  namespace this_thread = detail::this_thread_stl;
+#elif TD_THREAD_UNSUPPORTED
+  namespace this_thread {
+    inline void yield() {}
+  }
+#else
+  #error "Thread's implementation is not defined"
+#endif
+
+// clang-format on
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/thread_local.cpp b/libs/tdlib/td/tdutils/td/utils/port/thread_local.cpp
new file mode 100644
index 0000000000..aa4e371405
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/thread_local.cpp
@@ -0,0 +1,41 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/thread_local.h"
+
+#include "td/utils/logging.h"
+
+namespace td {
+
+namespace detail {
+
+static TD_THREAD_LOCAL int32 thread_id_;
+static TD_THREAD_LOCAL std::vector<std::unique_ptr<Guard>> *thread_local_destructors;
+
+void add_thread_local_destructor(std::unique_ptr<Guard> destructor) {
+  if (thread_local_destructors == nullptr) {
+    thread_local_destructors = new std::vector<std::unique_ptr<Guard>>();
+  }
+  thread_local_destructors->push_back(std::move(destructor));
+}
+
+}  // namespace detail
+
+void clear_thread_locals() {
+  // ensure that no destructors were added during destructors invokation
+  auto to_delete = detail::thread_local_destructors;
+  detail::thread_local_destructors = nullptr;
+  delete to_delete;
+  CHECK(detail::thread_local_destructors == nullptr);
+}
+void set_thread_id(int32 id) {
+  detail::thread_id_ = id;
+}
+
+int32 get_thread_id() {
+  return detail::thread_id_;
+}
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/thread_local.h b/libs/tdlib/td/tdutils/td/utils/port/thread_local.h
new file mode 100644
index 0000000000..6d8c135e88
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/thread_local.h
@@ -0,0 +1,69 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#include "td/utils/common.h"
+#include "td/utils/ScopeGuard.h"
+
+#include <memory>
+#include <utility>
+
+namespace td {
+
+// clang-format off
+#if TD_GCC || TD_CLANG
+  #define TD_THREAD_LOCAL __thread
+#elif TD_INTEL || TD_MSVC
+  #define TD_THREAD_LOCAL thread_local
+#else
+  #warning "TD_THREAD_LOCAL is not defined, trying 'thread_local'"
+  #define TD_THREAD_LOCAL thread_local
+#endif
+// clang-format on
+
+inline constexpr size_t max_thread_count() {
+  return 256;
+}
+
+// If raw_ptr is not nullptr, allocate T as in std::make_unique<T>(args...) and store pointer into raw_ptr
+template <class T, class P, class... ArgsT>
+bool init_thread_local(P &raw_ptr, ArgsT &&... args);
+
+// Destroy all thread locals, and store nullptr into corresponding pointers
+void clear_thread_locals();
+
+void set_thread_id(int32 id);
+
+int32 get_thread_id();
+
+namespace detail {
+void add_thread_local_destructor(std::unique_ptr<Guard> destructor);
+
+template <class T, class P, class... ArgsT>
+void do_init_thread_local(P &raw_ptr, ArgsT &&... args) {
+  auto ptr = std::make_unique<T>(std::forward<ArgsT>(args)...);
+  raw_ptr = ptr.get();
+
+  detail::add_thread_local_destructor(create_lambda_guard([ptr = std::move(ptr), &raw_ptr]() mutable {
+    ptr.reset();
+    raw_ptr = nullptr;
+  }));
+}
+}  // namespace detail
+
+template <class T, class P, class... ArgsT>
+bool init_thread_local(P &raw_ptr, ArgsT &&... args) {
+  if (likely(raw_ptr != nullptr)) {
+    return false;
+  }
+  detail::do_init_thread_local<T>(raw_ptr, std::forward<ArgsT>(args)...);
+  return true;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/port/wstring_convert.cpp b/libs/tdlib/td/tdutils/td/utils/port/wstring_convert.cpp
new file mode 100644
index 0000000000..56da62b96d
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/wstring_convert.cpp
@@ -0,0 +1,63 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/wstring_convert.h"
+
+char disable_linker_warning_about_empty_file_wstring_convert_cpp TD_UNUSED;
+
+#if TD_PORT_WINDOWS
+
+#define _SILENCE_CXX17_CODECVT_HEADER_DEPRECATION_WARNING
+
+#include "td/utils/port/wstring_convert.h"
+
+#include <codecvt>
+#include <locale>
+#include <utility>
+
+namespace td {
+
+namespace detail {
+template <class Facet>
+class UsableFacet : public Facet {
+ public:
+  template <class... Args>
+  explicit UsableFacet(Args &&... args) : Facet(std::forward<Args>(args)...) {
+  }
+  ~UsableFacet() = default;
+};
+}  // namespace detail
+
+Result<std::wstring> to_wstring(Slice slice) {
+  // TODO(perf): optimize
+  std::wstring_convert<detail::UsableFacet<std::codecvt_utf8_utf16<wchar_t>>> converter;
+  auto res = converter.from_bytes(slice.begin(), slice.end());
+  if (converter.converted() != slice.size()) {
+    return Status::Error("Wrong encoding");
+  }
+  return res;
+}
+
+Result<string> from_wstring(const wchar_t *begin, size_t size) {
+  std::wstring_convert<detail::UsableFacet<std::codecvt_utf8_utf16<wchar_t>>> converter;
+  auto res = converter.to_bytes(begin, begin + size);
+  if (converter.converted() != size) {
+    return Status::Error("Wrong encoding");
+  }
+  return res;
+}
+
+Result<string> from_wstring(const std::wstring &str) {
+  return from_wstring(str.data(), str.size());
+}
+
+Result<string> from_wstring(const wchar_t *begin) {
+  return from_wstring(begin, wcslen(begin));
+}
+
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/port/wstring_convert.h b/libs/tdlib/td/tdutils/td/utils/port/wstring_convert.h
new file mode 100644
index 0000000000..a795d2bd92
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/port/wstring_convert.h
@@ -0,0 +1,31 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/config.h"
+
+#if TD_PORT_WINDOWS
+
+#include "td/utils/common.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include <string>
+
+namespace td {
+
+Result<std::wstring> to_wstring(Slice slice);
+
+Result<string> from_wstring(const std::wstring &str);
+
+Result<string> from_wstring(const wchar_t *begin, size_t size);
+
+Result<string> from_wstring(const wchar_t *begin);
+
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/queue.h b/libs/tdlib/td/tdutils/td/utils/queue.h
new file mode 100644
index 0000000000..6d107e37f2
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/queue.h
@@ -0,0 +1,484 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/port/EventFd.h"
+#include "td/utils/port/thread.h"
+
+#if !TD_THREAD_UNSUPPORTED && !TD_EVENTFD_UNSUPPORTED
+
+#if !TD_WINDOWS
+#include <poll.h>
+#include <sched.h>
+#endif
+
+#include <atomic>
+#include <type_traits>
+#include <utility>
+
+namespace td {
+
+namespace detail {
+class Backoff {
+  int cnt = 0;
+
+ public:
+  bool next() {
+    // TODO: find out better strategy
+    // TODO: try adaptive backoff
+    // TODO: different strategy one core cpu
+    // return false;
+
+    cnt++;
+    if (cnt < 1) {  // 50
+      return true;
+    } else {
+      td::this_thread::yield();
+      return cnt < 3;  // 500
+    }
+  }
+};
+
+class InfBackoff {
+  int cnt = 0;
+
+ public:
+  bool next() {
+    cnt++;
+    if (cnt < 50) {
+      return true;
+    } else {
+      td::this_thread::yield();
+      return true;
+    }
+  }
+};
+
+}  // namespace detail
+
+template <class T, int P = 10>
+class SPSCBlockQueue {
+ public:
+  using ValueType = T;
+
+ private:
+  static constexpr int buffer_size() {
+    static_assert(P >= 1 && P <= 20, "Bad size of BlockQueue");
+    return 1 << P;
+  }
+
+  struct Position {
+    std::atomic<uint32> i;
+    char pad[64 - sizeof(std::atomic<uint32>)];
+    uint32 local_writer_i;
+    char pad2[64 - sizeof(uint32)];
+    uint32 local_reader_i;
+    char pad3[64 - sizeof(uint32)];
+
+    void init() {
+      i = 0;
+      local_reader_i = 0;
+      local_writer_i = 0;
+    }
+  };
+
+  typename std::aligned_storage<sizeof(ValueType)>::type data_[buffer_size()];
+  Position writer_;
+  Position reader_;
+
+  static int fix_i(int i) {
+    return i & (buffer_size() - 1);
+  }
+
+  ValueType *at_ptr(int i) {
+    return reinterpret_cast<ValueType *>(&data_[fix_i(i)]);
+  }
+
+  ValueType &at(int i) {
+    return *at_ptr(i);
+  }
+
+ public:
+  void init() {
+    writer_.init();
+    reader_.init();
+  }
+
+  void destroy() {
+  }
+
+  int writer_size() {
+    return static_cast<int>(writer_.local_reader_i + buffer_size() - writer_.local_writer_i);
+  }
+
+  bool writer_empty() {
+    return writer_.local_reader_i + buffer_size() == writer_.local_writer_i;
+  }
+
+  template <class PutValueType>
+  void writer_put_unsafe(PutValueType &&value) {
+    at(writer_.local_writer_i++) = std::forward<PutValueType>(value);
+  }
+
+  int writer_update() {
+    writer_.local_reader_i = reader_.i.load(std::memory_order_acquire);
+    return writer_size();
+  }
+
+  void writer_flush() {
+    writer_.i.store(writer_.local_writer_i, std::memory_order_release);
+  }
+
+  int reader_size() {
+    return static_cast<int>(reader_.local_writer_i - reader_.local_reader_i);
+  }
+
+  int reader_empty() {
+    return reader_.local_writer_i == reader_.local_reader_i;
+  }
+
+  ValueType reader_get_unsafe() {
+    return std::move(at(reader_.local_reader_i++));
+  }
+
+  int reader_update() {
+    reader_.local_writer_i = writer_.i.load(std::memory_order_acquire);
+    return reader_size();
+  }
+
+  void reader_flush() {
+    reader_.i.store(reader_.local_reader_i, std::memory_order_release);
+  }
+};
+
+template <class T, class BlockQueueT = SPSCBlockQueue<T> >
+class SPSCChainQueue {
+ public:
+  using ValueType = T;
+
+  void init() {
+    head_ = tail_ = create_node();
+  }
+
+  SPSCChainQueue() = default;
+  SPSCChainQueue(const SPSCChainQueue &) = delete;
+  SPSCChainQueue &operator=(const SPSCChainQueue &) = delete;
+  SPSCChainQueue(SPSCChainQueue &&) = delete;
+  SPSCChainQueue &operator=(SPSCChainQueue &&) = delete;
+  ~SPSCChainQueue() {
+    destroy();
+  }
+
+  void destroy() {
+    while (head_ != nullptr) {
+      Node *to_delete = head_;
+      head_ = head_->next_;
+      delete_node(to_delete);
+    }
+    tail_ = nullptr;
+  }
+
+  int writer_size() {
+    return tail_->q_.writer_size();
+  }
+
+  bool writer_empty() {
+    return tail_->q_.writer_empty();
+  }
+
+  template <class PutValueType>
+  void writer_put_unsafe(PutValueType &&value) {
+    tail_->q_.writer_put_unsafe(std::forward<PutValueType>(value));
+  }
+
+  int writer_update() {
+    int res = tail_->q_.writer_update();
+    if (res != 0) {
+      return res;
+    }
+
+    writer_flush();
+
+    Node *new_tail = create_node();
+    tail_->next_ = new_tail;
+    tail_->is_closed_.store(true, std::memory_order_release);
+    tail_ = new_tail;
+    return tail_->q_.writer_update();
+  }
+
+  void writer_flush() {
+    tail_->q_.writer_flush();
+  }
+
+  int reader_size() {
+    return head_->q_.reader_size();
+  }
+
+  int reader_empty() {
+    return head_->q_.reader_empty();
+  }
+
+  ValueType reader_get_unsafe() {
+    return std::move(head_->q_.reader_get_unsafe());
+  }
+
+  int reader_update() {
+    int res = head_->q_.reader_update();
+    if (res != 0) {
+      return res;
+    }
+
+    if (!head_->is_closed_.load(std::memory_order_acquire)) {
+      return 0;
+    }
+
+    res = head_->q_.reader_update();
+    if (res != 0) {
+      return res;
+    }
+
+    // reader_flush();
+
+    Node *old_head = head_;
+    head_ = head_->next_;
+    delete_node(old_head);
+
+    return head_->q_.reader_update();
+  }
+
+  void reader_flush() {
+    head_->q_.reader_flush();
+  }
+
+ private:
+  struct Node {
+    BlockQueueT q_;
+    std::atomic<bool> is_closed_;
+    Node *next_;
+
+    void init() {
+      q_.init();
+      is_closed_ = false;
+      next_ = nullptr;
+    }
+
+    void destroy() {
+      q_.destroy();
+      next_ = nullptr;
+    }
+  };
+
+  Node *head_;
+  char pad[64 - sizeof(Node *)];
+  Node *tail_;
+  char pad2[64 - sizeof(Node *)];
+
+  Node *create_node() {
+    Node *res = new Node();
+    res->init();
+    return res;
+  }
+
+  void delete_node(Node *node) {
+    node->destroy();
+    delete node;
+  }
+};
+
+template <class T, class QueueT = SPSCChainQueue<T>, class BackoffT = detail::Backoff>
+class BackoffQueue : public QueueT {
+ public:
+  using ValueType = T;
+
+  template <class PutValueType>
+  void writer_put(PutValueType &&value) {
+    if (this->writer_empty()) {
+      int sz = this->writer_update();
+      CHECK(sz != 0);
+    }
+    this->writer_put_unsafe(std::forward<PutValueType>(value));
+  }
+
+  int reader_wait() {
+    BackoffT backoff;
+    int res = 0;
+    do {
+      res = this->reader_update();
+    } while (res == 0 && backoff.next());
+    return res;
+  }
+};
+
+template <class T, class QueueT = SPSCChainQueue<T> >
+using InfBackoffQueue = BackoffQueue<T, QueueT, detail::InfBackoff>;
+
+template <class T, class QueueT = BackoffQueue<T> >
+class PollQueue : public QueueT {
+ public:
+  using ValueType = T;
+  using QueueType = QueueT;
+
+  void init() {
+    QueueType::init();
+    event_fd_.init();
+    wait_state_ = 0;
+    writer_wait_state_ = 0;
+  }
+
+  PollQueue() = default;
+  PollQueue(const PollQueue &) = delete;
+  PollQueue &operator=(const PollQueue &) = delete;
+  PollQueue(PollQueue &&) = delete;
+  PollQueue &operator=(PollQueue &&) = delete;
+  ~PollQueue() {
+    destroy_impl();
+  }
+  void destroy() {
+    destroy_impl();
+    QueueType::destroy();
+  }
+
+  void writer_flush() {
+    int old_wait_state = get_wait_state();
+
+    std::atomic_thread_fence(std::memory_order_seq_cst);
+
+    QueueType::writer_flush();
+
+    std::atomic_thread_fence(std::memory_order_seq_cst);
+
+    int wait_state = get_wait_state();
+    if ((wait_state & 1) && wait_state != writer_wait_state_) {
+      event_fd_.release();
+      writer_wait_state_ = old_wait_state;
+    }
+  }
+
+  EventFd &reader_get_event_fd() {
+    return event_fd_;
+  }
+
+  // if 0 is returned than it is useless to rerun it before fd is
+  // ready to read.
+  int reader_wait_nonblock() {
+    int res;
+
+    if ((get_wait_state() & 1) == 0) {
+      res = this->QueueType::reader_wait();
+      if (res != 0) {
+        return res;
+      }
+
+      inc_wait_state();
+
+      std::atomic_thread_fence(std::memory_order_seq_cst);
+
+      res = this->reader_update();
+      if (res != 0) {
+        inc_wait_state();
+        return res;
+      }
+    }
+
+    event_fd_.acquire();
+    std::atomic_thread_fence(std::memory_order_seq_cst);
+    res = this->reader_update();
+    if (res != 0) {
+      inc_wait_state();
+    }
+    return res;
+  }
+
+// Just example of usage
+#if !TD_WINDOWS
+  int reader_wait() {
+    int res;
+
+    while ((res = reader_wait_nonblock()) == 0) {
+      // TODO: reader_flush?
+      pollfd fd;
+      fd.fd = reader_get_event_fd().get_fd().get_native_fd();
+      fd.events = POLLIN;
+      poll(&fd, 1, -1);
+    }
+    return res;
+  }
+#endif
+
+ private:
+  EventFd event_fd_;
+  std::atomic<int> wait_state_;
+  int writer_wait_state_;
+
+  int get_wait_state() {
+    return wait_state_.load(std::memory_order_relaxed);
+  }
+
+  void inc_wait_state() {
+    wait_state_.store(get_wait_state() + 1, std::memory_order_relaxed);
+  }
+
+  void destroy_impl() {
+    if (!event_fd_.empty()) {
+      event_fd_.close();
+    }
+  }
+};
+
+}  // namespace td
+
+#else
+
+#include "td/utils/logging.h"
+
+namespace td {
+
+// dummy implementation which shouldn't be used
+
+template <class T>
+class PollQueue {
+ public:
+  using ValueType = T;
+
+  void init() {
+    UNREACHABLE();
+  }
+
+  template <class PutValueType>
+  void writer_put(PutValueType &&value) {
+    UNREACHABLE();
+  }
+
+  void writer_flush() {
+    UNREACHABLE();
+  }
+
+  int reader_wait_nonblock() {
+    UNREACHABLE();
+    return 0;
+  }
+
+  ValueType reader_get_unsafe() {
+    UNREACHABLE();
+    return ValueType();
+  }
+
+  void reader_flush() {
+    UNREACHABLE();
+  }
+
+  PollQueue() = default;
+  PollQueue(const PollQueue &) = delete;
+  PollQueue &operator=(const PollQueue &) = delete;
+  PollQueue(PollQueue &&) = delete;
+  PollQueue &operator=(PollQueue &&) = delete;
+  ~PollQueue() = default;
+};
+
+}  // namespace td
+
+#endif
diff --git a/libs/tdlib/td/tdutils/td/utils/tests.h b/libs/tdlib/td/tdutils/td/utils/tests.h
new file mode 100644
index 0000000000..24e2f3fe22
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/tests.h
@@ -0,0 +1,205 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/List.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/thread.h"
+#include "td/utils/Random.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Time.h"
+
+#include <atomic>
+
+#define REGISTER_TESTS(x)                \
+  void TD_CONCAT(register_tests_, x)() { \
+  }
+#define DESC_TESTS(x) void TD_CONCAT(register_tests_, x)()
+#define LOAD_TESTS(x) TD_CONCAT(register_tests_, x)()
+
+namespace td {
+
+class Test : private ListNode {
+ public:
+  explicit Test(CSlice name) : name_(name) {
+    get_tests_list()->put_back(this);
+  }
+
+  Test(const Test &) = delete;
+  Test &operator=(const Test &) = delete;
+  Test(Test &&) = delete;
+  Test &operator=(Test &&) = delete;
+  virtual ~Test() = default;
+
+  static void add_substr_filter(std::string str) {
+    if (str[0] != '+' && str[0] != '-') {
+      str = "+" + str;
+    }
+    get_substr_filters()->push_back(std::move(str));
+  }
+  static void set_stress_flag(bool flag) {
+    get_stress_flag() = flag;
+  }
+  static void run_all() {
+    while (run_all_step()) {
+    }
+  }
+
+  static bool run_all_step() {
+    auto *state = get_state();
+    if (state->it == nullptr) {
+      state->end = get_tests_list();
+      state->it = state->end->next;
+    }
+
+    while (state->it != state->end) {
+      auto test = static_cast<td::Test *>(state->it);
+      if (!state->is_running) {
+        bool ok = true;
+        for (const auto &filter : *get_substr_filters()) {
+          bool is_match = test->name_.str().find(filter.substr(1)) != std::string::npos;
+          if (is_match != (filter[0] == '+')) {
+            ok = false;
+            break;
+          }
+        }
+        if (!ok) {
+          state->it = state->it->next;
+          continue;
+        }
+        LOG(ERROR) << "Run test " << tag("name", test->name_);
+        state->start = Time::now();
+        state->is_running = true;
+      }
+
+      if (test->step()) {
+        break;
+      }
+
+      LOG(ERROR) << format::as_time(Time::now() - state->start);
+      state->is_running = false;
+      state->it = state->it->next;
+    }
+
+    auto ret = state->it != state->end;
+    if (!ret) {
+      *state = State();
+    }
+    return ret || get_stress_flag();
+  }
+
+ private:
+  CSlice name_;
+  struct State {
+    ListNode *it = nullptr;
+    bool is_running = false;
+    double start;
+    ListNode *end = nullptr;
+  };
+  static State *get_state() {
+    static State state;
+    return &state;
+  }
+  static std::vector<std::string> *get_substr_filters() {
+    static std::vector<std::string> substr_filters_;
+    return &substr_filters_;
+  }
+
+  static ListNode *get_tests_list() {
+    static ListNode root;
+    return &root;
+  }
+  static bool &get_ok_flag() {
+    static bool is_ok = true;
+    return is_ok;
+  }
+  static bool &get_stress_flag() {
+    static bool stress_flag = false;
+    return stress_flag;
+  }
+  virtual void run() {
+    while (step()) {
+    }
+  }
+
+  virtual bool step() {
+    run();
+    return false;
+  }
+};
+
+class Stage {
+ public:
+  void wait(uint64 need) {
+    value_.fetch_add(1, std::memory_order_release);
+    while (value_.load(std::memory_order_acquire) < need) {
+      td::this_thread::yield();
+    }
+  };
+
+ private:
+  std::atomic<uint64> value_{0};
+};
+
+inline string rand_string(char from, char to, int len) {
+  string res(len, 0);
+  for (auto &c : res) {
+    c = static_cast<char>(Random::fast(from, to));
+  }
+  return res;
+}
+
+inline std::vector<string> rand_split(string str) {
+  std::vector<string> res;
+  size_t pos = 0;
+  while (pos < str.size()) {
+    size_t len;
+    if (Random::fast(0, 1) == 1) {
+      len = Random::fast(1, 10);
+    } else {
+      len = Random::fast(100, 200);
+    }
+    res.push_back(str.substr(pos, len));
+    pos += len;
+  }
+  return res;
+}
+
+template <class T1, class T2>
+void assert_eq_impl(const T1 &expected, const T2 &got, const char *file, int line) {
+  CHECK(expected == got) << tag("expected", expected) << tag("got", got) << " in " << file << " at line " << line;
+}
+
+template <class T>
+void assert_true_impl(const T &got, const char *file, int line) {
+  CHECK(got) << "Expected true in " << file << " at line " << line;
+}
+
+}  // namespace td
+
+#define ASSERT_EQ(expected, got) ::td::assert_eq_impl((expected), (got), __FILE__, __LINE__)
+
+#define ASSERT_TRUE(got) ::td::assert_true_impl((got), __FILE__, __LINE__)
+
+#define ASSERT_STREQ(expected, got) \
+  ::td::assert_eq_impl(::td::Slice((expected)), ::td::Slice((got)), __FILE__, __LINE__)
+
+#define TEST_NAME(test_case_name, test_name) \
+  TD_CONCAT(Test, TD_CONCAT(_, TD_CONCAT(test_case_name, TD_CONCAT(_, test_name))))
+
+#define TEST(test_case_name, test_name) TEST_IMPL(TEST_NAME(test_case_name, test_name))
+
+#define TEST_IMPL(test_name)                                                                     \
+  class test_name : public ::td::Test {                                                          \
+   public:                                                                                       \
+    using Test::Test;                                                                            \
+    void run() final;                                                                            \
+  };                                                                                             \
+  test_name TD_CONCAT(test_instance_, TD_CONCAT(test_name, __LINE__))(TD_DEFINE_STR(test_name)); \
+  void test_name::run()
diff --git a/libs/tdlib/td/tdutils/td/utils/tl_helpers.h b/libs/tdlib/td/tdutils/td/utils/tl_helpers.h
new file mode 100644
index 0000000000..686dacbeef
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/tl_helpers.h
@@ -0,0 +1,203 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Slice.h"
+#include "td/utils/StackAllocator.h"
+#include "td/utils/Status.h"
+#include "td/utils/tl_parsers.h"
+#include "td/utils/tl_storers.h"
+
+#include <type_traits>
+#include <unordered_set>
+
+#define BEGIN_STORE_FLAGS() \
+  uint32 flags_store = 0;   \
+  uint32 bit_offset_store = 0
+
+#define STORE_FLAG(flag)                     \
+  flags_store |= (flag) << bit_offset_store; \
+  bit_offset_store++
+
+#define END_STORE_FLAGS()       \
+  CHECK(bit_offset_store < 31); \
+  td::store(flags_store, storer)
+
+#define BEGIN_PARSE_FLAGS()    \
+  uint32 flags_parse;          \
+  uint32 bit_offset_parse = 0; \
+  td::parse(flags_parse, parser)
+
+#define PARSE_FLAG(flag)                               \
+  flag = ((flags_parse >> bit_offset_parse) & 1) != 0; \
+  bit_offset_parse++
+
+#define END_PARSE_FLAGS()       \
+  CHECK(bit_offset_parse < 31); \
+  CHECK((flags_parse & ~((1 << bit_offset_parse) - 1)) == 0) << flags_parse << " " << bit_offset_parse;
+
+namespace td {
+template <class StorerT>
+void store(bool x, StorerT &storer) {
+  storer.store_binary(static_cast<int32>(x));
+}
+template <class ParserT>
+void parse(bool &x, ParserT &parser) {
+  x = parser.fetch_int() != 0;
+}
+
+template <class StorerT>
+void store(int32 x, StorerT &storer) {
+  storer.store_binary(x);
+}
+template <class ParserT>
+void parse(int32 &x, ParserT &parser) {
+  x = parser.fetch_int();
+}
+
+template <class StorerT>
+void store(uint32 x, StorerT &storer) {
+  storer.store_binary(x);
+}
+template <class ParserT>
+void parse(uint32 &x, ParserT &parser) {
+  x = static_cast<uint32>(parser.fetch_int());
+}
+
+template <class StorerT>
+void store(int64 x, StorerT &storer) {
+  storer.store_binary(x);
+}
+template <class ParserT>
+void parse(int64 &x, ParserT &parser) {
+  x = parser.fetch_long();
+}
+template <class StorerT>
+void store(uint64 x, StorerT &storer) {
+  storer.store_binary(x);
+}
+template <class ParserT>
+void parse(uint64 &x, ParserT &parser) {
+  x = static_cast<uint64>(parser.fetch_long());
+}
+
+template <class StorerT>
+void store(double x, StorerT &storer) {
+  storer.store_binary(x);
+}
+template <class ParserT>
+void parse(double &x, ParserT &parser) {
+  x = parser.fetch_double();
+}
+
+template <class StorerT>
+void store(Slice x, StorerT &storer) {
+  storer.store_string(x);
+}
+template <class StorerT>
+void store(const string &x, StorerT &storer) {
+  storer.store_string(x);
+}
+template <class ParserT>
+void parse(string &x, ParserT &parser) {
+  x = parser.template fetch_string<string>();
+}
+
+template <class T, class StorerT>
+void store(const vector<T> &vec, StorerT &storer) {
+  storer.store_binary(narrow_cast<int32>(vec.size()));
+  for (auto &val : vec) {
+    store(val, storer);
+  }
+}
+template <class T, class ParserT>
+void parse(vector<T> &vec, ParserT &parser) {
+  uint32 size = parser.fetch_int();
+  if (parser.get_left_len() < size) {
+    parser.set_error("Wrong vector length");
+    return;
+  }
+  vec = vector<T>(size);
+  for (auto &val : vec) {
+    parse(val, parser);
+  }
+}
+
+template <class Key, class Hash, class KeyEqual, class Allocator, class StorerT>
+void store(const std::unordered_set<Key, Hash, KeyEqual, Allocator> &s, StorerT &storer) {
+  storer.store_binary(narrow_cast<int32>(s.size()));
+  for (auto &val : s) {
+    store(val, storer);
+  }
+}
+template <class Key, class Hash, class KeyEqual, class Allocator, class ParserT>
+void parse(std::unordered_set<Key, Hash, KeyEqual, Allocator> &s, ParserT &parser) {
+  uint32 size = parser.fetch_int();
+  if (parser.get_left_len() < size) {
+    parser.set_error("Wrong set length");
+    return;
+  }
+  s.clear();
+  Key val;
+  for (uint32 i = 0; i < size; i++) {
+    parse(val, parser);
+    s.insert(std::move(val));
+  }
+}
+
+template <class T, class StorerT>
+std::enable_if_t<std::is_enum<T>::value> store(const T &val, StorerT &storer) {
+  store(static_cast<int32>(val), storer);
+}
+template <class T, class ParserT>
+std::enable_if_t<std::is_enum<T>::value> parse(T &val, ParserT &parser) {
+  int32 result;
+  parse(result, parser);
+  val = static_cast<T>(result);
+}
+
+template <class T, class StorerT>
+std::enable_if_t<!std::is_enum<T>::value> store(const T &val, StorerT &storer) {
+  val.store(storer);
+}
+template <class T, class ParserT>
+std::enable_if_t<!std::is_enum<T>::value> parse(T &val, ParserT &parser) {
+  val.parse(parser);
+}
+
+template <class T>
+string serialize(const T &object) {
+  TlStorerCalcLength calc_length;
+  store(object, calc_length);
+  size_t length = calc_length.get_length();
+
+  string key(length, '\0');
+  if (!is_aligned_pointer<4>(key.data())) {
+    auto ptr = StackAllocator::alloc(length);
+    MutableSlice data = ptr.as_slice();
+    TlStorerUnsafe storer(data.begin());
+    store(object, storer);
+    key.assign(data.begin(), data.size());
+  } else {
+    MutableSlice data = key;
+    TlStorerUnsafe storer(data.begin());
+    store(object, storer);
+  }
+  return key;
+}
+
+template <class T>
+TD_WARN_UNUSED_RESULT Status unserialize(T &object, Slice data) {
+  TlParser parser(data);
+  parse(object, parser);
+  parser.fetch_end();
+  return parser.get_status();
+}
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/tl_parsers.cpp b/libs/tdlib/td/tdutils/td/utils/tl_parsers.cpp
new file mode 100644
index 0000000000..534e7793cf
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/tl_parsers.cpp
@@ -0,0 +1,29 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/tl_parsers.h"
+
+namespace td {
+
+alignas(4) const unsigned char TlParser::empty_data[sizeof(UInt256)] = {};  // static zero-initialized
+
+void TlParser::set_error(const string &error_message) {
+  if (error.empty()) {
+    CHECK(!error_message.empty());
+    error = error_message;
+    error_pos = data_len - left_len;
+    data = empty_data;
+    left_len = 0;
+    data_len = 0;
+  } else {
+    data = empty_data;
+    CHECK(error_pos != std::numeric_limits<size_t>::max());
+    CHECK(data_len == 0);
+    CHECK(left_len == 0);
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/tl_parsers.h b/libs/tdlib/td/tdutils/td/utils/tl_parsers.h
new file mode 100644
index 0000000000..ffb669bdeb
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/tl_parsers.h
@@ -0,0 +1,242 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/buffer.h"
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/utf8.h"
+
+#include <array>
+#include <cstring>
+#include <limits>
+#include <string>
+
+namespace td {
+
+class TlParser {
+  const unsigned char *data = nullptr;
+  size_t data_len = 0;
+  size_t left_len = 0;
+  size_t error_pos = std::numeric_limits<size_t>::max();
+  std::string error;
+
+  unique_ptr<int32[]> data_buf;
+  static constexpr size_t SMALL_DATA_ARRAY_SIZE = 6;
+  std::array<int32, SMALL_DATA_ARRAY_SIZE> small_data_array;
+
+  alignas(4) static const unsigned char empty_data[sizeof(UInt256)];
+
+ public:
+  explicit TlParser(Slice slice) {
+    if (slice.size() % sizeof(int32) != 0) {
+      set_error("Wrong length");
+      return;
+    }
+
+    data_len = left_len = slice.size();
+    if (is_aligned_pointer<4>(slice.begin())) {
+      data = slice.ubegin();
+    } else {
+      int32 *buf;
+      if (data_len <= small_data_array.size() * sizeof(int32)) {
+        buf = &small_data_array[0];
+      } else {
+        LOG(ERROR) << "Unexpected big unaligned data pointer of length " << slice.size() << " at " << slice.begin();
+        data_buf = make_unique<int32[]>(data_len / sizeof(int32));
+        buf = data_buf.get();
+      }
+      std::memcpy(static_cast<void *>(buf), static_cast<const void *>(slice.begin()), slice.size());
+      data = reinterpret_cast<unsigned char *>(buf);
+    }
+  }
+
+  TlParser(const TlParser &other) = delete;
+  TlParser &operator=(const TlParser &other) = delete;
+
+  void set_error(const string &error_message);
+
+  const char *get_error() const {
+    if (error.empty()) {
+      return nullptr;
+    }
+    return error.c_str();
+  }
+
+  size_t get_error_pos() const {
+    return error_pos;
+  }
+
+  Status get_status() const {
+    if (error.empty()) {
+      return Status::OK();
+    }
+    return Status::Error(PSLICE() << error << " at " << error_pos);
+  }
+
+  void check_len(const size_t len) {
+    if (unlikely(left_len < len)) {
+      set_error("Not enough data to read");
+    } else {
+      left_len -= len;
+    }
+  }
+
+  int32 fetch_int_unsafe() {
+    int32 result = *reinterpret_cast<const int32 *>(data);
+    data += sizeof(int32);
+    return result;
+  }
+
+  int32 fetch_int() {
+    check_len(sizeof(int32));
+    return fetch_int_unsafe();
+  }
+
+  int64 fetch_long_unsafe() {
+    int64 result;
+    std::memcpy(reinterpret_cast<unsigned char *>(&result), data, sizeof(int64));
+    data += sizeof(int64);
+    return result;
+  }
+
+  int64 fetch_long() {
+    check_len(sizeof(int64));
+    return fetch_long_unsafe();
+  }
+
+  double fetch_double_unsafe() {
+    double result;
+    std::memcpy(reinterpret_cast<unsigned char *>(&result), data, sizeof(double));
+    data += sizeof(double);
+    return result;
+  }
+
+  double fetch_double() {
+    check_len(sizeof(double));
+    return fetch_double_unsafe();
+  }
+
+  template <class T>
+  T fetch_binary_unsafe() {
+    T result;
+    std::memcpy(reinterpret_cast<unsigned char *>(&result), data, sizeof(T));
+    data += sizeof(T);
+    return result;
+  }
+
+  template <class T>
+  T fetch_binary() {
+    static_assert(sizeof(T) <= sizeof(empty_data), "too big fetch_binary");
+    static_assert(sizeof(T) % sizeof(int32) == 0, "wrong call to fetch_binary");
+    check_len(sizeof(T));
+    return fetch_binary_unsafe<T>();
+  }
+
+  template <class T>
+  T fetch_string() {
+    check_len(sizeof(int32));
+    size_t result_len = *data;
+    const char *result_begin;
+    size_t result_aligned_len;
+    if (result_len < 254) {
+      result_begin = reinterpret_cast<const char *>(data + 1);
+      result_aligned_len = (result_len >> 2) << 2;
+    } else if (result_len == 254) {
+      result_len = data[1] + (data[2] << 8) + (data[3] << 16);
+      result_begin = reinterpret_cast<const char *>(data + 4);
+      result_aligned_len = ((result_len + 3) >> 2) << 2;
+    } else {
+      set_error("Can't fetch string, 255 found");
+      return T();
+    }
+    check_len(result_aligned_len);
+    data += result_aligned_len + sizeof(int32);
+    return T(result_begin, result_len);
+  }
+
+  template <class T>
+  T fetch_string_raw(const size_t size) {
+    CHECK(size % sizeof(int32) == 0);
+    check_len(size);
+    const char *result = reinterpret_cast<const char *>(data);
+    data += size;
+    return T(result, size);
+  }
+
+  void fetch_end() {
+    if (left_len) {
+      set_error("Too much data to fetch");
+    }
+  }
+
+  size_t get_left_len() const {
+    return left_len;
+  }
+};
+
+class TlBufferParser : public TlParser {
+ public:
+  explicit TlBufferParser(const BufferSlice *buffer_slice) : TlParser(buffer_slice->as_slice()), parent_(buffer_slice) {
+  }
+  template <class T>
+  T fetch_string() {
+    auto result = TlParser::fetch_string<T>();
+    for (auto &c : result) {
+      if (c == '\0') {
+        c = ' ';
+      }
+    }
+    if (check_utf8(result)) {
+      return result;
+    }
+    CHECK(!result.empty());
+    LOG(WARNING) << "Wrong UTF-8 string [[" << result << "]] in " << format::as_hex_dump<4>(parent_->as_slice());
+
+    // trying to remove last character
+    size_t new_size = result.size() - 1;
+    while (new_size != 0 && !is_utf8_character_first_code_unit(static_cast<unsigned char>(result[new_size]))) {
+      new_size--;
+    }
+    result.resize(new_size);
+    if (check_utf8(result)) {
+      return result;
+    }
+
+    return T();
+  }
+  template <class T>
+  T fetch_string_raw(const size_t size) {
+    return TlParser::fetch_string_raw<T>(size);
+  }
+
+ private:
+  const BufferSlice *parent_;
+
+  BufferSlice as_buffer_slice(Slice slice) {
+    if (is_aligned_pointer<4>(slice.data())) {
+      return parent_->from_slice(slice);
+    }
+    return BufferSlice(slice);
+  }
+};
+
+template <>
+inline BufferSlice TlBufferParser::fetch_string<BufferSlice>() {
+  return as_buffer_slice(TlParser::fetch_string<Slice>());
+}
+
+template <>
+inline BufferSlice TlBufferParser::fetch_string_raw<BufferSlice>(const size_t size) {
+  return as_buffer_slice(TlParser::fetch_string_raw<Slice>(size));
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/tl_storers.h b/libs/tdlib/td/tdutils/td/utils/tl_storers.h
new file mode 100644
index 0000000000..f389451d8a
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/tl_storers.h
@@ -0,0 +1,281 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/int_types.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Slice.h"
+#include "td/utils/StorerBase.h"
+
+#include <cstring>
+
+namespace td {
+
+class TlStorerUnsafe {
+  char *buf;
+
+ public:
+  explicit TlStorerUnsafe(char *buf) : buf(buf) {
+    CHECK(is_aligned_pointer<4>(buf));
+  }
+
+  TlStorerUnsafe(const TlStorerUnsafe &other) = delete;
+  TlStorerUnsafe &operator=(const TlStorerUnsafe &other) = delete;
+
+  template <class T>
+  void store_binary(const T &x) {
+    std::memcpy(buf, reinterpret_cast<const unsigned char *>(&x), sizeof(T));
+    buf += sizeof(T);
+  }
+
+  void store_int(int32 x) {
+    *reinterpret_cast<int32 *>(buf) = x;
+    buf += sizeof(int32);
+  }
+
+  void store_long(int64 x) {
+    store_binary<int64>(x);
+  }
+
+  void store_slice(Slice slice) {
+    std::memcpy(buf, slice.begin(), slice.size());
+    buf += slice.size();
+  }
+  void store_storer(const Storer &storer) {
+    size_t size = storer.store(reinterpret_cast<unsigned char *>(buf));
+    buf += size;
+  }
+
+  template <class T>
+  void store_string(const T &str) {
+    size_t len = str.size();
+    if (len < 254) {
+      *buf++ = static_cast<char>(len);
+      len++;
+    } else if (len < (1 << 24)) {
+      *buf++ = static_cast<char>(static_cast<unsigned char>(254));
+      *buf++ = static_cast<char>(len & 255);
+      *buf++ = static_cast<char>((len >> 8) & 255);
+      *buf++ = static_cast<char>(len >> 16);
+    } else {
+      LOG(FATAL) << "String size " << len << " is too big to be stored";
+    }
+    std::memcpy(buf, str.data(), str.size());
+    buf += str.size();
+
+    switch (len & 3) {
+      case 1:
+        *buf++ = '\0';
+      // fallthrough
+      case 2:
+        *buf++ = '\0';
+      // fallthrough
+      case 3:
+        *buf++ = '\0';
+    }
+  }
+
+  char *get_buf() const {
+    return buf;
+  }
+};
+
+class TlStorerCalcLength {
+  size_t length = 0;
+
+ public:
+  TlStorerCalcLength() = default;
+  TlStorerCalcLength(const TlStorerCalcLength &other) = delete;
+  TlStorerCalcLength &operator=(const TlStorerCalcLength &other) = delete;
+
+  template <class T>
+  void store_binary(const T &x) {
+    length += sizeof(T);
+  }
+
+  void store_int(int32 x) {
+    store_binary<int32>(x);
+  }
+
+  void store_long(int64 x) {
+    store_binary<int64>(x);
+  }
+
+  void store_slice(Slice slice) {
+    length += slice.size();
+  }
+
+  void store_storer(const Storer &storer) {
+    length += storer.size();
+  }
+
+  template <class T>
+  void store_string(const T &str) {
+    size_t add = str.size();
+    if (add < 254) {
+      add += 1;
+    } else {
+      add += 4;
+    }
+    add = (add + 3) & -4;
+    length += add;
+  }
+
+  size_t get_length() const {
+    return length;
+  }
+};
+
+class TlStorerToString {
+  std::string result;
+  int shift = 0;
+
+  void store_field_begin(const char *name) {
+    for (int i = 0; i < shift; i++) {
+      result += ' ';
+    }
+    if (name && name[0]) {
+      result += name;
+      result += " = ";
+    }
+  }
+
+  void store_field_end() {
+    result += "\n";
+  }
+
+  void store_long(int64 value) {
+    result += (PSLICE() << value).c_str();
+  }
+
+  void store_binary(Slice data) {
+    static const char *hex = "0123456789ABCDEF";
+
+    result.append("{ ");
+    for (auto c : data) {
+      unsigned char byte = c;
+      result += hex[byte >> 4];
+      result += hex[byte & 15];
+      result += ' ';
+    }
+    result.append("}");
+  }
+
+ public:
+  TlStorerToString() = default;
+  TlStorerToString(const TlStorerToString &other) = delete;
+  TlStorerToString &operator=(const TlStorerToString &other) = delete;
+
+  void store_field(const char *name, bool value) {
+    store_field_begin(name);
+    result += (value ? "true" : "false");
+    store_field_end();
+  }
+
+  void store_field(const char *name, int32 value) {
+    store_field(name, static_cast<int64>(value));
+  }
+
+  void store_field(const char *name, int64 value) {
+    store_field_begin(name);
+    store_long(value);
+    store_field_end();
+  }
+
+  void store_field(const char *name, double value) {
+    store_field_begin(name);
+    result += (PSLICE() << value).c_str();
+    store_field_end();
+  }
+
+  void store_field(const char *name, const char *value) {
+    store_field_begin(name);
+    result += value;
+    store_field_end();
+  }
+
+  void store_field(const char *name, const string &value) {
+    store_field_begin(name);
+    result += '"';
+    result.append(value.data(), value.size());
+    result += '"';
+    store_field_end();
+  }
+
+  template <class T>
+  void store_field(const char *name, const T &value) {
+    store_field_begin(name);
+    result.append(value.data(), value.size());
+    store_field_end();
+  }
+
+  template <class BytesT>
+  void store_bytes_field(const char *name, const BytesT &value) {
+    static const char *hex = "0123456789ABCDEF";
+
+    store_field_begin(name);
+    result.append("bytes { ");
+    for (size_t i = 0; i < value.size(); i++) {
+      int b = value[static_cast<int>(i)] & 0xff;
+      result += hex[b >> 4];
+      result += hex[b & 15];
+      result += ' ';
+    }
+    result.append("}");
+    store_field_end();
+  }
+
+  void store_field(const char *name, const UInt128 &value) {
+    store_field_begin(name);
+    store_binary(Slice(reinterpret_cast<const unsigned char *>(&value), sizeof(value)));
+    store_field_end();
+  }
+
+  void store_field(const char *name, const UInt256 &value) {
+    store_field_begin(name);
+    store_binary(Slice(reinterpret_cast<const unsigned char *>(&value), sizeof(value)));
+    store_field_end();
+  }
+
+  void store_class_begin(const char *field_name, const char *class_name) {
+    store_field_begin(field_name);
+    result += class_name;
+    result += " {\n";
+    shift += 2;
+  }
+
+  void store_class_end() {
+    shift -= 2;
+    for (int i = 0; i < shift; i++) {
+      result += ' ';
+    }
+    result += "}\n";
+    CHECK(shift >= 0);
+  }
+
+  std::string str() const {
+    return result;
+  }
+};
+
+template <class T>
+size_t tl_calc_length(const T &data) {
+  TlStorerCalcLength storer_calc_length;
+  data.store(storer_calc_length);
+  return storer_calc_length.get_length();
+}
+
+template <class T, class CharT>
+size_t tl_store_unsafe(const T &data, CharT *dst) {
+  char *start = reinterpret_cast<char *>(dst);
+  TlStorerUnsafe storer_unsafe(start);
+  data.store(storer_unsafe);
+  return storer_unsafe.get_buf() - start;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/type_traits.h b/libs/tdlib/td/tdutils/td/utils/type_traits.h
new file mode 100644
index 0000000000..ef9c159420
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/type_traits.h
@@ -0,0 +1,22 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+namespace td {
+
+template <class FunctionT>
+struct member_function_class;
+
+template <class ReturnType, class Type>
+struct member_function_class<ReturnType Type::*> {
+  using type = Type;
+};
+
+template <class FunctionT>
+using member_function_class_t = typename member_function_class<FunctionT>::type;
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/unicode.cpp b/libs/tdlib/td/tdutils/td/utils/unicode.cpp
new file mode 100644
index 0000000000..11e76b7979
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/unicode.cpp
@@ -0,0 +1,574 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/unicode.h"
+
+#include "td/utils/logging.h"
+
+#include <algorithm>
+#include <iterator>
+
+namespace td {
+
+// list of [(range_begin << 5) + range_type]
+static const uint32 unicode_simple_category_ranges[] = {
+    0,       1028,    1056,    1538,    1856,    2081,    2912,    3105,      3936,    5124,    5152,    5441,
+    5472,    5699,    5760,    5793,    5824,    5923,    5953,    5984,      6019,    6112,    6145,    6880,
+    6913,    7904,    7937,    22592,   22721,   23104,   23553,   23712,     23937,   23968,   24001,   24032,
+    28161,   28320,   28353,   28416,   28481,   28608,   28641,   28672,     28865,   28896,   28929,   29024,
+    29057,   29088,   29121,   29760,   29793,   32448,   32481,   36928,     37185,   42496,   42529,   43744,
+    43809,   43840,   44065,   45312,   47617,   48480,   48641,   48736,     50177,   51552,   52226,   52544,
+    52673,   52736,   52769,   55936,   55969,   56000,   56481,   56544,     56769,   56834,   57153,   57248,
+    57313,   57344,   57857,   57888,   57921,   58880,   59809,   62656,     63009,   63040,   63490,   63809,
+    64864,   65153,   65216,   65345,   65376,   65537,   66240,   66369,     66400,   66689,   66720,   66817,
+    66848,   67585,   68384,   70657,   71328,   71361,   71616,   73857,     75584,   75681,   75712,   76289,
+    76320,   76545,   76864,   76994,   77312,   77345,   77856,   77985,     78240,   78305,   78368,   78433,
+    79136,   79169,   79392,   79425,   79456,   79553,   79680,   79777,     79808,   80321,   80352,   80769,
+    80832,   80865,   80960,   81090,   81409,   81472,   81539,   81728,     82081,   82272,   82401,   82464,
+    82529,   83232,   83265,   83488,   83521,   83584,   83617,   83680,     83713,   83776,   84769,   84896,
+    84929,   84960,   85186,   85504,   85569,   85664,   86177,   86464,     86497,   86592,   86625,   87328,
+    87361,   87584,   87617,   87680,   87713,   87872,   87969,   88000,     88577,   88608,   89089,   89152,
+    89282,   89600,   89889,   89920,   90273,   90528,   90593,   90656,     90721,   91424,   91457,   91680,
+    91713,   91776,   91809,   91968,   92065,   92096,   93057,   93120,     93153,   93248,   93378,   93696,
+    93729,   93763,   93952,   94305,   94336,   94369,   94560,   94657,     94752,   94785,   94912,   95009,
+    95072,   95105,   95136,   95169,   95232,   95329,   95392,   95489,     95584,   95681,   96064,   96769,
+    96800,   97474,   97795,   97888,   98465,   98720,   98753,   98848,     98881,   99616,   99649,   100160,
+    100257,  100288,  101121,  101216,  101377,  101440,  101570,  101888,    102147,  102368,  102401,  102432,
+    102561,  102816,  102849,  102944,  102977,  103712,  103745,  104064,    104097,  104256,  104353,  104384,
+    105409,  105440,  105473,  105536,  105666,  105984,  106017,  106080,    106657,  106912,  106945,  107040,
+    107073,  108384,  108449,  108480,  108993,  109024,  109185,  109280,    109315,  109537,  109632,  109762,
+    110083,  110368,  110401,  110592,  110753,  111328,  111425,  112192,    112225,  112512,  112545,  112576,
+    112641,  112864,  113858,  114176,  114721,  116256,  116289,  116352,    116737,  116960,  117250,  117568,
+    118817,  118880,  118913,  118944,  119009,  119072,  119105,  119136,    119201,  119232,  119425,  119552,
+    119585,  119808,  119841,  119936,  119969,  120000,  120033,  120064,    120129,  120192,  120225,  120352,
+    120385,  120448,  120737,  120768,  120833,  120992,  121025,  121056,    121346,  121664,  121729,  121856,
+    122881,  122912,  123906,  124227,  124544,  124929,  125184,  125217,    126368,  127233,  127392,  131073,
+    132448,  133089,  133122,  133440,  133633,  133824,  133953,  134080,    134177,  134208,  134305,  134368,
+    134593,  134688,  134817,  135232,  135617,  135648,  135682,  136000,    136193,  137408,  137441,  137472,
+    137633,  137664,  137729,  139104,  139137,  149792,  149825,  149952,    150017,  150240,  150273,  150304,
+    150337,  150464,  150529,  151840,  151873,  152000,  152065,  153120,    153153,  153280,  153345,  153568,
+    153601,  153632,  153665,  153792,  153857,  154336,  154369,  156192,    156225,  156352,  156417,  158560,
+    159011,  159648,  159745,  160256,  160769,  163520,  163585,  163776,    163873,  183712,  183777,  184324,
+    184353,  185184,  185345,  187744,  187843,  187937,  188192,  188417,    188832,  188865,  188992,  189441,
+    190016,  190465,  191040,  191489,  191904,  191937,  192032,  192513,    194176,  195297,  195328,  195457,
+    195488,  195586,  195904,  196099,  196416,  197122,  197440,  197633,    200448,  200705,  200864,  200929,
+    202016,  202049,  202080,  202241,  204480,  204801,  205792,  207042,    207361,  208320,  208385,  208544,
+    208897,  210304,  210433,  211264,  211458,  211779,  211808,  212993,    213728,  214017,  215712,  217090,
+    217408,  217602,  217920,  218337,  218368,  221345,  222848,  223393,    223616,  223746,  224064,  225377,
+    226336,  226753,  226818,  227137,  228544,  229377,  230528,  231426,    231744,  231841,  231938,  232257,
+    233408,  233473,  233760,  236833,  236960,  236993,  237120,  237217,    237280,  237569,  243712,  245761,
+    254656,  254721,  254912,  254977,  256192,  256257,  256448,  256513,    256768,  256801,  256832,  256865,
+    256896,  256929,  256960,  256993,  257984,  258049,  259744,  259777,    260000,  260033,  260064,  260161,
+    260256,  260289,  260512,  260609,  260736,  260801,  260992,  261121,    261536,  261697,  261792,  261825,
+    262048,  262148,  262496,  263428,  263488,  263652,  263680,  265188,    265216,  265731,  265761,  265792,
+    265859,  266048,  266209,  266243,  266560,  266753,  267168,  270401,    270432,  270561,  270592,  270657,
+    270976,  271009,  271040,  271137,  271296,  271489,  271520,  271553,    271584,  271617,  271648,  271681,
+    271808,  271841,  272192,  272257,  272384,  272545,  272704,  272833,    272864,  272899,  274529,  274595,
+    274752,  297987,  299904,  302403,  303104,  323267,  324224,  360449,    361952,  361985,  363488,  363521,
+    367776,  367969,  368096,  368193,  368256,  368547,  368576,  368641,    369856,  369889,  369920,  370081,
+    370112,  370177,  371968,  372193,  372224,  372737,  373472,  373761,    373984,  374017,  374240,  374273,
+    374496,  374529,  374752,  374785,  375008,  375041,  375264,  375297,    375520,  375553,  375776,  378337,
+    378368,  393220,  393248,  393377,  393443,  393472,  394275,  394560,    394785,  394944,  395011,  395105,
+    395168,  395297,  398048,  398241,  398336,  398369,  401248,  401281,    401408,  401569,  402880,  402977,
+    405984,  406083,  406208,  406529,  407392,  409089,  409600,  410627,    410944,  411907,  412160,  412195,
+    412672,  413699,  414016,  415267,  415744,  425985,  636608,  638977,    1309376, 1310721, 1348000, 1350145,
+    1351616, 1351681, 1360288, 1360385, 1360898, 1361217, 1361280, 1361921,   1363424, 1363937, 1364928, 1364993,
+    1367235, 1367552, 1368801, 1369088, 1369153, 1372448, 1372513, 1373664,   1373697, 1373952, 1375969, 1376320,
+    1376353, 1376448, 1376481, 1376608, 1376641, 1377376, 1377795, 1377984,   1378305, 1379968, 1380417, 1382016,
+    1382914, 1383232, 1384001, 1384192, 1384289, 1384320, 1384353, 1384384,   1384450, 1384769, 1385664, 1385985,
+    1386720, 1387521, 1388448, 1388673, 1390176, 1391073, 1391106, 1391424,   1391617, 1391776, 1391809, 1392130,
+    1392449, 1392608, 1392641, 1393952, 1394689, 1394784, 1394817, 1395072,   1395202, 1395520, 1395713, 1396448,
+    1396545, 1396576, 1396673, 1398272, 1398305, 1398336, 1398433, 1398496,   1398561, 1398720, 1398785, 1398816,
+    1398849, 1398880, 1399649, 1399744, 1399809, 1400160, 1400385, 1400480,   1400865, 1401056, 1401121, 1401312,
+    1401377, 1401568, 1401857, 1402080, 1402113, 1402336, 1402369, 1403744,   1403777, 1404096, 1404417, 1408096,
+    1408514, 1408832, 1409025, 1766528, 1766913, 1767648, 1767777, 1769344,   2039809, 2051520, 2051585, 2054976,
+    2056193, 2056416, 2056801, 2056960, 2057121, 2057152, 2057185, 2057504,   2057537, 2057952, 2057985, 2058144,
+    2058177, 2058208, 2058241, 2058304, 2058337, 2058400, 2058433, 2061888,   2062945, 2074560, 2075137, 2077184,
+    2077249, 2078976, 2080257, 2080640, 2084353, 2084512, 2084545, 2088864,   2089474, 2089792, 2090017, 2090848,
+    2091041, 2091872, 2092225, 2095072, 2095169, 2095360, 2095425, 2095616,   2095681, 2095872, 2095937, 2096032,
+    2097153, 2097536, 2097569, 2098400, 2098433, 2099040, 2099073, 2099136,   2099169, 2099648, 2099713, 2100160,
+    2101249, 2105184, 2105571, 2107008, 2107395, 2109216, 2109763, 2109824,   2117633, 2118560, 2118657, 2120224,
+    2120739, 2121600, 2121729, 2122755, 2122880, 2123265, 2123811, 2123841,   2124099, 2124128, 2124289, 2125504,
+    2125825, 2126784, 2126849, 2128000, 2128129, 2128384, 2128419, 2128576,   2129921, 2134976, 2135042, 2135360,
+    2135553, 2136704, 2136833, 2137984, 2138113, 2139392, 2139649, 2141312,   2146305, 2156256, 2156545, 2157248,
+    2157569, 2157824, 2162689, 2162880, 2162945, 2162976, 2163009, 2164416,   2164449, 2164512, 2164609, 2164640,
+    2164705, 2165440, 2165507, 2165761, 2166496, 2166563, 2166785, 2167776,   2168035, 2168320, 2169857, 2170464,
+    2170497, 2170560, 2170723, 2170881, 2171587, 2171776, 2171905, 2172736,   2174977, 2176768, 2176899, 2176961,
+    2177027, 2177536, 2177603, 2179073, 2179104, 2179585, 2179712, 2179745,   2179840, 2179873, 2180736, 2181123,
+    2181376, 2182145, 2183075, 2183136, 2183169, 2184099, 2184192, 2185217,   2185472, 2185505, 2186400, 2186595,
+    2186752, 2187265, 2188992, 2189313, 2190016, 2190083, 2190337, 2190944,   2191107, 2191361, 2191936, 2192675,
+    2192896, 2195457, 2197792, 2199553, 2201184, 2201601, 2203232, 2203459,   2203648, 2214915, 2215904, 2228321,
+    2230016, 2230851, 2231490, 2231808, 2232417, 2233856, 2234881, 2235680,   2235906, 2236224, 2236513, 2237664,
+    2238146, 2238464, 2238977, 2240096, 2240193, 2240224, 2240609, 2242144,   2242593, 2242720, 2243074, 2243393,
+    2243424, 2243457, 2243488, 2243619, 2244256, 2244609, 2245184, 2245217,   2246016, 2248705, 2248928, 2248961,
+    2248992, 2249025, 2249152, 2249185, 2249664, 2249697, 2250016, 2250241,   2251744, 2252290, 2252608, 2252961,
+    2253216, 2253281, 2253344, 2253409, 2254112, 2254145, 2254368, 2254401,   2254464, 2254497, 2254656, 2254753,
+    2254784, 2255361, 2255392, 2255777, 2255936, 2260993, 2262688, 2263265,   2263392, 2263554, 2263872, 2265089,
+    2266624, 2267265, 2267328, 2267361, 2267392, 2267650, 2267968, 2273281,   2274784, 2276097, 2276224, 2277377,
+    2278912, 2279553, 2279584, 2279938, 2280256, 2281473, 2282848, 2283522,   2283840, 2285569, 2286400, 2287106,
+    2287427, 2287488, 2298881, 2300930, 2301251, 2301536, 2301921, 2301952,   2316289, 2318112, 2326529, 2326816,
+    2326849, 2328032, 2328577, 2328608, 2329090, 2329411, 2330016, 2330177,   2331136, 2359297, 2388800, 2392067,
+    2395616, 2396161, 2402432, 2490369, 2524640, 2654209, 2672864, 2949121,   2967328, 2967553, 2968544, 2968578,
+    2968896, 2972161, 2973120, 2973697, 2975232, 2975745, 2975872, 2976258,   2976576, 2976611, 2976832, 2976865,
+    2977536, 2977697, 2978304, 3006465, 3008672, 3009025, 3009056, 3011169,   3011584, 3013633, 3013664, 3014657,
+    3210656, 3211265, 3235424, 3538945, 3539008, 3637249, 3640672, 3640833,   3641248, 3641345, 3641632, 3641857,
+    3642176, 3828739, 3829312, 3833857, 3836576, 3836609, 3838880, 3838913,   3838976, 3839041, 3839072, 3839137,
+    3839200, 3839265, 3839392, 3839425, 3839808, 3839841, 3839872, 3839905,   3840128, 3840161, 3842240, 3842273,
+    3842400, 3842465, 3842720, 3842753, 3842976, 3843009, 3843904, 3843937,   3844064, 3844097, 3844256, 3844289,
+    3844320, 3844417, 3844640, 3844673, 3855552, 3855617, 3856416, 3856449,   3857248, 3857281, 3858272, 3858305,
+    3859104, 3859137, 3860128, 3860161, 3860960, 3860993, 3861984, 3862017,   3862816, 3862849, 3863840, 3863873,
+    3864672, 3864705, 3864960, 3865026, 3866624, 3997697, 4004000, 4004067,   4004352, 4005889, 4008064, 4008450,
+    4008768, 4046849, 4046976, 4047009, 4047872, 4047905, 4047968, 4048001,   4048032, 4048097, 4048128, 4048161,
+    4048480, 4048513, 4048640, 4048673, 4048704, 4048737, 4048768, 4048961,   4048992, 4049121, 4049152, 4049185,
+    4049216, 4049249, 4049280, 4049313, 4049408, 4049441, 4049504, 4049537,   4049568, 4049633, 4049664, 4049697,
+    4049728, 4049761, 4049792, 4049825, 4049856, 4049889, 4049920, 4049953,   4050016, 4050049, 4050080, 4050145,
+    4050272, 4050305, 4050528, 4050561, 4050688, 4050721, 4050848, 4050881,   4050912, 4050945, 4051264, 4051297,
+    4051840, 4052001, 4052096, 4052129, 4052288, 4052321, 4052864, 4071427,   4071840, 4194305, 5561056, 5562369,
+    5695136, 5695489, 5702592, 5702657, 5887040, 6225921, 6243264, 4294967295};
+
+static constexpr uint32 TABLE_SIZE = 1280;
+
+static int16 prepare_search_character_table[TABLE_SIZE] = {
+    0,     32,   32,   32,   32,    32,   32,   32,   32,   32,   32,   32,   32,   32,   32,   32,   32,   32,   32,
+    32,    32,   32,   32,   32,    32,   32,   32,   32,   32,   32,   32,   32,   32,   32,   32,   32,   32,   32,
+    32,    32,   32,   32,   32,    32,   32,   32,   32,   32,   48,   49,   50,   51,   52,   53,   54,   55,   56,
+    57,    32,   32,   32,   32,    32,   32,   32,   97,   98,   99,   100,  101,  102,  103,  104,  105,  106,  107,
+    108,   109,  110,  111,  112,   113,  114,  115,  116,  117,  118,  119,  120,  121,  122,  32,   32,   32,   32,
+    32,    32,   97,   98,   99,    100,  101,  102,  103,  104,  105,  106,  107,  108,  109,  110,  111,  112,  113,
+    114,   115,  116,  117,  118,   119,  120,  121,  122,  32,   32,   32,   32,   32,   32,   32,   32,   32,   32,
+    32,    32,   32,   32,   32,    32,   32,   32,   32,   32,   32,   32,   32,   32,   32,   32,   32,   32,   32,
+    32,    32,   32,   32,   32,    32,   32,   32,   32,   32,   32,   32,   32,   32,   32,   32,   32,   32,   170,
+    32,    32,   0,    32,   32,    32,   32,   178,  179,  32,   956,  32,   0,    32,   185,  186,  32,   188,  189,
+    190,   32,   224,  225,  226,   227,  228,  229,  230,  231,  232,  233,  234,  235,  236,  237,  238,  239,  240,
+    241,   242,  243,  244,  245,   246,  32,   248,  249,  250,  251,  252,  253,  254,  223,  224,  225,  226,  227,
+    228,   229,  230,  231,  232,   233,  234,  235,  236,  237,  238,  239,  240,  241,  242,  243,  244,  245,  246,
+    32,    248,  249,  250,  251,   252,  253,  254,  255,  257,  257,  259,  259,  261,  261,  263,  263,  265,  265,
+    267,   267,  269,  269,  271,   271,  273,  273,  275,  275,  277,  277,  279,  279,  281,  281,  283,  283,  285,
+    285,   287,  287,  289,  289,   291,  291,  293,  293,  295,  295,  297,  297,  299,  299,  301,  301,  303,  303,
+    105,   305,  307,  307,  309,   309,  311,  311,  312,  314,  314,  316,  316,  318,  318,  320,  320,  322,  322,
+    324,   324,  326,  326,  328,   328,  329,  331,  331,  333,  333,  335,  335,  337,  337,  339,  339,  341,  341,
+    343,   343,  345,  345,  347,   347,  349,  349,  351,  351,  353,  353,  355,  355,  357,  357,  359,  359,  361,
+    361,   363,  363,  365,  365,   367,  367,  369,  369,  371,  371,  373,  373,  375,  375,  255,  378,  378,  380,
+    380,   382,  382,  115,  384,   595,  387,  387,  389,  389,  596,  392,  392,  598,  599,  396,  396,  397,  477,
+    601,   603,  402,  402,  608,   611,  405,  617,  616,  409,  409,  410,  411,  623,  626,  414,  629,  417,  417,
+    419,   419,  421,  421,  640,   424,  424,  643,  426,  427,  429,  429,  648,  432,  432,  650,  651,  436,  436,
+    438,   438,  658,  441,  441,   442,  443,  445,  445,  446,  447,  448,  449,  450,  451,  454,  454,  454,  457,
+    457,   457,  460,  460,  460,   462,  462,  464,  464,  466,  466,  468,  468,  470,  470,  472,  472,  474,  474,
+    476,   476,  477,  479,  479,   481,  481,  483,  483,  485,  485,  487,  487,  489,  489,  491,  491,  493,  493,
+    495,   495,  496,  499,  499,   499,  501,  501,  405,  447,  505,  505,  507,  507,  509,  509,  511,  511,  513,
+    513,   515,  515,  517,  517,   519,  519,  521,  521,  523,  523,  525,  525,  527,  527,  529,  529,  531,  531,
+    533,   533,  535,  535,  537,   537,  539,  539,  541,  541,  543,  543,  414,  545,  547,  547,  549,  549,  551,
+    551,   553,  553,  555,  555,   557,  557,  559,  559,  561,  561,  563,  563,  564,  565,  566,  567,  568,  569,
+    11365, 572,  572,  410,  11366, 575,  576,  578,  578,  384,  649,  652,  583,  583,  585,  585,  587,  587,  589,
+    589,   591,  591,  592,  593,   594,  595,  596,  597,  598,  599,  600,  601,  602,  603,  604,  605,  606,  607,
+    608,   609,  610,  611,  612,   613,  614,  615,  616,  617,  618,  619,  620,  621,  622,  623,  624,  625,  626,
+    627,   628,  629,  630,  631,   632,  633,  634,  635,  636,  637,  638,  639,  640,  641,  642,  643,  644,  645,
+    646,   647,  648,  649,  650,   651,  652,  653,  654,  655,  656,  657,  658,  659,  660,  661,  662,  663,  664,
+    665,   666,  667,  668,  669,   670,  671,  672,  673,  674,  675,  676,  677,  678,  679,  680,  681,  682,  683,
+    684,   685,  686,  687,  688,   689,  690,  691,  692,  693,  694,  695,  696,  697,  698,  699,  0,    701,  0,
+    703,   704,  705,  32,   32,    32,   32,   710,  711,  712,  713,  714,  715,  716,  717,  718,  719,  720,  721,
+    32,    32,   32,   32,   32,    32,   32,   32,   32,   32,   32,   32,   32,   32,   736,  737,  738,  739,  740,
+    32,    32,   32,   32,   32,    32,   32,   748,  32,   750,  32,   32,   32,   32,   32,   32,   32,   32,   32,
+    32,    32,   32,   32,   32,    32,   32,   32,   0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,     0,    0,    0,    0,     0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,     0,    0,    0,    0,     0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,     0,    0,    0,    0,     0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,     837,  0,    0,    0,     0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,     0,    0,    0,    0,     0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,     0,    0,    0,    0,     0,    881,  881,  883,  883,  884,  32,   887,  887,  888,  889,  890,  891,  892,
+    893,   32,   1011, 896,  897,   898,  899,  32,   32,   940,  32,   941,  942,  943,  907,  972,  909,  973,  974,
+    912,   945,  946,  947,  948,   949,  950,  951,  952,  953,  954,  955,  956,  957,  958,  959,  960,  961,  930,
+    963,   964,  965,  966,  967,   968,  969,  970,  971,  940,  941,  942,  943,  944,  945,  946,  947,  948,  949,
+    950,   951,  952,  953,  954,   955,  956,  957,  958,  959,  960,  961,  963,  963,  964,  965,  966,  967,  968,
+    969,   970,  971,  972,  973,   974,  983,  946,  952,  965,  965,  965,  966,  960,  983,  985,  985,  987,  987,
+    989,   989,  991,  991,  993,   993,  995,  995,  997,  997,  999,  999,  1001, 1001, 1003, 1003, 1005, 1005, 1007,
+    1007,  954,  961,  963,  1011,  952,  949,  32,   1016, 1016, 1010, 1019, 1019, 1020, 891,  892,  893,  1104, 1105,
+    1106,  1107, 1108, 1109, 1110,  1111, 1112, 1113, 1114, 1115, 1116, 1117, 1118, 1119, 1072, 1073, 1074, 1075, 1076,
+    1077,  1078, 1079, 1080, 1081,  1082, 1083, 1084, 1085, 1086, 1087, 1088, 1089, 1090, 1091, 1092, 1093, 1094, 1095,
+    1096,  1097, 1098, 1099, 1100,  1101, 1102, 1103, 1072, 1073, 1074, 1075, 1076, 1077, 1078, 1079, 1080, 1081, 1082,
+    1083,  1084, 1085, 1086, 1087,  1088, 1089, 1090, 1091, 1092, 1093, 1094, 1095, 1096, 1097, 1098, 1099, 1100, 1101,
+    1102,  1103, 1104, 1105, 1106,  1107, 1108, 1109, 1110, 1111, 1112, 1113, 1114, 1115, 1116, 1117, 1118, 1119, 1121,
+    1121,  1123, 1123, 1125, 1125,  1127, 1127, 1129, 1129, 1131, 1131, 1133, 1133, 1135, 1135, 1137, 1137, 1139, 1139,
+    1141,  1141, 1143, 1143, 1145,  1145, 1147, 1147, 1149, 1149, 1151, 1151, 1153, 1153, 32,   0,    0,    0,    0,
+    0,     0,    0,    1163, 1163,  1165, 1165, 1167, 1167, 1169, 1169, 1171, 1171, 1173, 1173, 1175, 1175, 1177, 1177,
+    1179,  1179, 1181, 1181, 1183,  1183, 1185, 1185, 1187, 1187, 1189, 1189, 1191, 1191, 1193, 1193, 1195, 1195, 1197,
+    1197,  1199, 1199, 1201, 1201,  1203, 1203, 1205, 1205, 1207, 1207, 1209, 1209, 1211, 1211, 1213, 1213, 1215, 1215,
+    1231,  1218, 1218, 1220, 1220,  1222, 1222, 1224, 1224, 1226, 1226, 1228, 1228, 1230, 1230, 1231, 1233, 1233, 1235,
+    1235,  1237, 1237, 1239, 1239,  1241, 1241, 1243, 1243, 1245, 1245, 1247, 1247, 1249, 1249, 1251, 1251, 1253, 1253,
+    1255,  1255, 1257, 1257, 1259,  1259, 1261, 1261, 1263, 1263, 1265, 1265, 1267, 1267, 1269, 1269, 1271, 1271, 1273,
+    1273,  1275, 1275, 1277, 1277,  1279, 1279};
+
+static const int32 prepare_search_character_ranges[] = {
+    1280,   2097153, 1328,   1328,    1329,    -1378,   1367,    -1368,    1370,    32,      1376,       -1377,
+    1417,   32,      1419,   -1420,   1421,    32,      1424,    1424,     1425,    0,       1470,       32,
+    1471,   0,       1472,   32,      1473,    0,       1475,    32,       1476,    0,       1478,       32,
+    1479,   0,       1480,   -1481,   1523,    32,      1525,    -1526,    1536,    0,       1542,       32,
+    1552,   0,       1563,   32,      1564,    0,       1565,    1565,     1566,    32,      1568,       -1569,
+    1611,   0,       1632,   -1633,   1642,    32,      1646,    -1647,    1648,    0,       1649,       -1650,
+    1748,   32,      1749,   1749,    1750,    0,       1758,    32,       1759,    0,       1765,       -1766,
+    1767,   0,       1769,   32,      1770,    0,       1774,    -1775,    1789,    32,      1791,       1791,
+    1792,   32,      1806,   1806,    1807,    0,       1808,    1808,     1809,    0,       1810,       -1811,
+    1840,   0,       1867,   -1868,   1958,    0,       1969,    -1970,    2027,    0,       2036,       -2037,
+    2038,   32,      2042,   -2043,   2070,    0,       2074,    2074,     2075,    0,       2084,       2084,
+    2085,   0,       2088,   2088,    2089,    0,       2094,    -2095,    2096,    32,      2111,       -2112,
+    2137,   0,       2140,   -2141,   2142,    32,      2143,    -2144,    2260,    0,       2308,       -2309,
+    2362,   0,       2365,   2365,    2366,    0,       2384,    2384,     2385,    0,       2392,       -2393,
+    2402,   0,       2404,   32,      2406,    -2407,   2416,    32,       2417,    -2418,   2433,       0,
+    2436,   -2437,   2492,   0,       2493,    2493,    2494,    0,        2501,    -2502,   2503,       0,
+    2505,   -2506,   2507,   0,       2510,    -2511,   2519,    0,        2520,    -2521,   2530,       0,
+    2532,   -2533,   2546,   32,      2548,    -2549,   2554,    32,       2556,    -2557,   2561,       0,
+    2564,   -2565,   2620,   0,       2621,    2621,    2622,    0,        2627,    -2628,   2631,       0,
+    2633,   -2634,   2635,   0,       2638,    -2639,   2641,    0,        2642,    -2643,   2672,       0,
+    2674,   -2675,   2677,   0,       2678,    -2679,   2689,    0,        2692,    -2693,   2748,       0,
+    2749,   2749,    2750,   0,       2758,    2758,    2759,    0,        2762,    2762,    2763,       0,
+    2766,   -2767,   2786,   0,       2788,    -2789,   2800,    32,       2802,    -2803,   2817,       0,
+    2820,   -2821,   2876,   0,       2877,    2877,    2878,    0,        2885,    -2886,   2887,       0,
+    2889,   -2890,   2891,   0,       2894,    -2895,   2902,    0,        2904,    -2905,   2914,       0,
+    2916,   -2917,   2928,   32,      2929,    -2930,   2946,    0,        2947,    -2948,   3006,       0,
+    3011,   -3012,   3014,   0,       3017,    3017,    3018,    0,        3022,    -3023,   3031,       0,
+    3032,   -3033,   3059,   32,      3067,    -3068,   3072,    0,        3076,    -3077,   3134,       0,
+    3141,   3141,    3142,   0,       3145,    3145,    3146,    0,        3150,    -3151,   3157,       0,
+    3159,   -3160,   3170,   0,       3172,    -3173,   3199,    32,       3200,    3200,    3201,       0,
+    3204,   -3205,   3260,   0,       3261,    3261,    3262,    0,        3269,    3269,    3270,       0,
+    3273,   3273,    3274,   0,       3278,    -3279,   3285,    0,        3287,    -3288,   3298,       0,
+    3300,   -3301,   3329,   0,       3332,    -3333,   3390,    0,        3397,    3397,    3398,       0,
+    3401,   3401,    3402,   0,       3406,    3406,    3407,    32,       3408,    -3409,   3415,       0,
+    3416,   -3417,   3426,   0,       3428,    -3429,   3449,    32,       3450,    -3451,   3458,       0,
+    3460,   -3461,   3530,   0,       3531,    -3532,   3535,    0,        3541,    3541,    3542,       0,
+    3543,   3543,    3544,   0,       3552,    -3553,   3570,    0,        3572,    32,      3573,       -3574,
+    3633,   0,       3634,   -3635,   3636,    0,       3643,    -3644,    3647,    32,      3648,       -3649,
+    3655,   0,       3663,   32,      3664,    -3665,   3674,    32,       3676,    -3677,   3761,       0,
+    3762,   -3763,   3764,   0,       3770,    3770,    3771,    0,        3773,    -3774,   3784,       0,
+    3790,   -3791,   3841,   32,      3864,    0,       3866,    32,       3872,    -3873,   3892,       32,
+    3893,   0,       3894,   32,      3895,    0,       3896,    32,       3897,    0,       3898,       32,
+    3902,   0,       3904,   -3905,   3953,    0,       3973,    32,       3974,    0,       3976,       -3977,
+    3981,   0,       3992,   3992,    3993,    0,       4029,    4029,     4030,    32,      4038,       0,
+    4039,   32,      4045,   4045,    4046,    32,      4059,    -4060,    4139,    0,       4159,       -4160,
+    4170,   32,      4176,   -4177,   4182,    0,       4186,    -4187,    4190,    0,       4193,       4193,
+    4194,   0,       4197,   -4198,   4199,    0,       4206,    -4207,    4209,    0,       4213,       -4214,
+    4226,   0,       4238,   4238,    4239,    0,       4240,    -4241,    4250,    0,       4254,       32,
+    4256,   -11521,  4294,   4294,    4295,    11559,   4296,    -4297,    4301,    11565,   4302,       -4303,
+    4347,   32,      4348,   -4349,   4957,    0,       4960,    32,       4969,    -4970,   5008,       32,
+    5018,   -5019,   5112,   -5105,   5118,    -5119,   5120,    32,       5121,    -5122,   5741,       32,
+    5743,   -5744,   5760,   32,      5761,    -5762,   5787,    32,       5789,    -5790,   5867,       32,
+    5870,   -5871,   5906,   0,       5909,    -5910,   5938,    0,        5941,    32,      5943,       -5944,
+    5970,   0,       5972,   -5973,   6002,    0,       6004,    -6005,    6068,    0,       6100,       32,
+    6103,   6103,    6104,   32,      6108,    6108,    6109,    0,        6110,    -6111,   6144,       32,
+    6155,   0,       6159,   -6160,   6277,    0,       6279,    -6280,    6313,    0,       6314,       -6315,
+    6432,   0,       6444,   -6445,   6448,    0,       6460,    -6461,    6464,    32,      6465,       -6466,
+    6468,   32,      6470,   -6471,   6622,    32,      6656,    -6657,    6679,    0,       6684,       -6685,
+    6686,   32,      6688,   -6689,   6741,    0,       6751,    6751,     6752,    0,       6781,       -6782,
+    6783,   0,       6784,   -6785,   6816,    32,      6823,    6823,     6824,    32,      6830,       -6831,
+    6832,   0,       6847,   -6848,   6912,    0,       6917,    -6918,    6964,    0,       6981,       -6982,
+    7002,   32,      7019,   0,       7028,    32,      7037,    -7038,    7040,    0,       7043,       -7044,
+    7073,   0,       7086,   -7087,   7142,    0,       7156,    -7157,    7164,    32,      7168,       -7169,
+    7204,   0,       7224,   -7225,   7227,    32,      7232,    -7233,    7294,    32,      7296,       1074,
+    7297,   1076,    7298,   1086,    7299,    -1090,   7301,    1090,     7302,    1098,    7303,       1123,
+    7304,   42571,   7305,   -7306,   7360,    32,      7368,    -7369,    7376,    0,       7379,       32,
+    7380,   0,       7401,   -7402,   7405,    0,       7406,    -7407,    7410,    0,       7413,       -7414,
+    7416,   0,       7418,   -7419,   7468,    97,      7469,    230,      7470,    98,      7471,       7471,
+    7472,   -101,    7474,   477,     7475,    -104,    7483,    7483,     7484,    111,     7485,       547,
+    7486,   112,     7487,   114,     7488,    -117,    7490,    119,      7491,    -7492,   7616,       0,
+    7670,   -7671,   7675,   0,       7680,    2097153, 7830,    -7831,    7835,    7777,    7836,       -7837,
+    7838,   223,     7839,   2097153, 7936,    -7937,   7944,    -7937,    7952,    -7953,   7960,       -7953,
+    7966,   -7967,   7976,   -7969,   7984,    -7985,   7992,    -7985,    8000,    -8001,   8008,       -8001,
+    8014,   -8015,   8025,   8017,    8026,    8026,    8027,    8019,     8028,    8028,    8029,       8021,
+    8030,   8030,    8031,   8023,    8032,    -8033,   8040,    -8033,    8048,    -8049,   8072,       -8065,
+    8080,   -8081,   8088,   -8081,   8096,    -8097,   8104,    -8097,    8112,    -8113,   8120,       -8113,
+    8122,   -8049,   8124,   8115,    8125,    32,      8126,    953,      8127,    32,      8130,       -8131,
+    8136,   -8051,   8140,   8131,    8141,    32,      8144,    -8145,    8152,    -8145,   8154,       -8055,
+    8156,   8156,    8157,   32,      8160,    -8161,   8168,    -8161,    8170,    -8059,   8172,       8165,
+    8173,   32,      8176,   -8177,   8184,    -8057,   8186,    -8061,    8188,    8179,    8189,       32,
+    8191,   8191,    8192,   32,      8203,    0,       8208,    32,       8234,    0,       8239,       32,
+    8288,   0,       8293,   8293,    8294,    0,       8304,    -8305,    8314,    32,      8319,       -8320,
+    8330,   32,      8335,   -8336,   8352,    32,      8383,    -8384,    8400,    0,       8433,       -8434,
+    8448,   32,      8450,   99,      8452,    32,      8455,    603,      8456,    32,      8457,       102,
+    8458,   8458,    8459,   104,     8462,    -8463,   8464,    105,      8466,    108,     8467,       8467,
+    8468,   32,      8469,   110,     8470,    32,      8473,    -113,     8476,    114,     8478,       32,
+    8484,   122,     8485,   32,      8486,    969,     8487,    32,       8488,    122,     8489,       32,
+    8490,   107,     8491,   229,     8492,    -99,     8494,    32,       8495,    8495,    8496,       -102,
+    8498,   8526,    8499,   109,     8500,    -8501,   8506,    32,       8508,    -8509,   8510,       947,
+    8511,   960,     8512,   32,      8517,    100,     8518,    -8519,    8522,    32,      8526,       8526,
+    8527,   32,      8528,   -8529,   8544,    -8561,   8560,    -8561,    8579,    8580,    8581,       -8582,
+    8586,   32,      8588,   -8589,   8592,    32,      9215,    9215,     9216,    32,      9255,       -9256,
+    9280,   32,      9291,   -9292,   9372,    32,      9398,    -9425,    9424,    -9425,   9472,       32,
+    10102,  -10103,  10132,  32,      11124,   -11125,  11126,   32,       11158,   -11159,  11160,      32,
+    11194,  -11195,  11197,  32,      11209,   11209,   11210,   32,       11218,   -11219,  11244,      32,
+    11248,  -11249,  11264,  -11313,  11311,   -11312,  11360,   11361,    11362,   619,     11363,      7549,
+    11364,  637,     11365,  -11366,  11367,   11368,   11369,   11370,    11371,   11372,   11373,      593,
+    11374,  625,     11375,  592,     11376,   594,     11377,   2097153,  11380,   11380,   11381,      11382,
+    11383,  -11384,  11389,  118,     11390,   -576,    11392,   2097153,  11492,   11492,   11493,      32,
+    11499,  11500,   11501,  11502,   11503,   0,       11506,   11507,    11508,   -11509,  11513,      32,
+    11517,  11517,   11518,  32,      11520,   -11521,  11632,   32,       11633,   -11634,  11647,      0,
+    11648,  -11649,  11744,  0,       11776,   32,      11823,   11823,    11824,   32,      11845,      -11846,
+    11904,  32,      11930,  11930,   11931,   32,      11935,   11935,    11936,   32,      12019,      -12020,
+    12272,  32,      12284,  -12285,  12288,   32,      12293,   -12294,   12296,   32,      12321,      -12322,
+    12330,  0,       12336,  32,      12337,   -12338,  12342,   32,       12344,   -12345,  12349,      32,
+    12352,  -12353,  12441,  0,       12443,   32,      12445,   -12446,   12448,   32,      12449,      -12450,
+    12539,  32,      12540,  0,       12541,   -12542,  12688,   32,       12690,   -12691,  12736,      32,
+    12772,  -12773,  12800,  32,      12831,   -12832,  12842,   32,       12868,   -12869,  12880,      32,
+    12881,  -12882,  12910,  32,      12928,   -12929,  12992,   32,       13008,   -13009,  13056,      32,
+    13312,  -13313,  19904,  32,      19968,   -19969,  42128,   32,       42183,   -42184,  42238,      32,
+    42240,  -42241,  42509,  32,      42512,   -42513,  42560,   2097153,  42606,   42606,   42607,      0,
+    42611,  32,      42612,  0,       42622,   32,      42623,   2097153,  42652,   -42653,  42654,      0,
+    42656,  -42657,  42736,  0,       42738,   32,      42744,   -42745,   42752,   32,      42775,      -42776,
+    42784,  32,      42786,  2097153, 42800,   -42801,  42802,   2097153,  42864,   -42865,  42873,      42874,
+    42875,  42876,   42877,  7545,    42878,   2097153, 42888,   42888,    42889,   32,      42891,      42892,
+    42893,  613,     42894,  -42895,  42896,   2097153, 42900,   -42901,   42902,   2097153, 42922,      614,
+    42923,  604,     42924,  609,     42925,   620,     42926,   618,      42927,   42927,   42928,      670,
+    42929,  647,     42930,  669,     42931,   43859,   42932,   2097153,  42936,   -42937,  43000,      295,
+    43001,  -43002,  43010,  0,       43011,   -43012,  43014,   0,        43015,   -43016,  43019,      0,
+    43020,  -43021,  43043,  0,       43048,   32,      43052,   -43053,   43062,   32,      43066,      -43067,
+    43124,  32,      43128,  -43129,  43136,   0,       43138,   -43139,   43188,   0,       43206,      -43207,
+    43214,  32,      43216,  -43217,  43232,   0,       43250,   -43251,   43256,   32,      43259,      43259,
+    43260,  32,      43261,  -43262,  43302,   0,       43310,   32,       43312,   -43313,  43335,      0,
+    43348,  -43349,  43359,  32,      43360,   -43361,  43392,   0,        43396,   -43397,  43443,      0,
+    43457,  32,      43470,  -43471,  43486,   32,      43488,   -43489,   43493,   0,       43494,      -43495,
+    43561,  0,       43575,  -43576,  43587,   0,       43588,   -43589,   43596,   0,       43598,      -43599,
+    43612,  32,      43616,  -43617,  43639,   32,      43642,   43642,    43643,   0,       43646,      -43647,
+    43696,  0,       43697,  43697,   43698,   0,       43701,   -43702,   43703,   0,       43705,      -43706,
+    43710,  0,       43712,  43712,   43713,   0,       43714,   -43715,   43742,   32,      43744,      -43745,
+    43755,  0,       43760,  32,      43762,   -43763,  43765,   0,        43767,   -43768,  43867,      32,
+    43868,  -43869,  43888,  -5025,   43968,   -43969,  44003,   0,        44011,   32,      44012,      0,
+    44014,  -44015,  55296,  0,       57344,   -57345,  64286,   0,        64287,   -64288,  64297,      32,
+    64298,  -64299,  64434,  32,      64450,   -64451,  64830,   32,       64832,   -64833,  64976,      32,
+    65008,  -65009,  65020,  32,      65022,   -65023,  65024,   0,        65040,   32,      65050,      -65051,
+    65056,  0,       65072,  32,      65107,   65107,   65108,   32,       65127,   65127,   65128,      32,
+    65132,  -65133,  65279,  0,       65280,   65280,   65281,   32,       65296,   -65297,  65306,      32,
+    65313,  -65346,  65339,  32,      65345,   -65346,  65371,   32,       65382,   -65383,  65504,      32,
+    65511,  65511,   65512,  32,      65519,   -65520,  65529,   0,        65532,   32,      65536,      -65537,
+    65792,  32,      65795,  -65796,  65847,   32,      65856,   -65857,   65913,   32,      65930,      -65931,
+    65932,  32,      65935,  65935,   65936,   32,      65948,   -65949,   65952,   32,      65953,      -65954,
+    66000,  32,      66045,  0,       66046,   -66047,  66272,   0,        66273,   -66274,  66422,      0,
+    66427,  -66428,  66463,  32,      66464,   -66465,  66512,   32,       66513,   -66514,  66560,      -66601,
+    66600,  -66601,  66736,  -66777,  66772,   -66773,  66927,   32,       66928,   -66929,  67671,      32,
+    67672,  -67673,  67703,  32,      67705,   -67706,  67871,   32,       67872,   -67873,  67903,      32,
+    67904,  -67905,  68097,  0,       68100,   68100,   68101,   0,        68103,   -68104,  68108,      0,
+    68112,  -68113,  68152,  0,       68155,   -68156,  68159,   0,        68160,   -68161,  68176,      32,
+    68185,  -68186,  68223,  32,      68224,   -68225,  68296,   32,       68297,   -68298,  68325,      0,
+    68327,  -68328,  68336,  32,      68343,   -68344,  68409,   32,       68416,   -68417,  68505,      32,
+    68509,  -68510,  68736,  -68801,  68787,   -68788,  69632,   0,        69635,   -69636,  69688,      0,
+    69703,  32,      69710,  -69711,  69759,   0,       69763,   -69764,   69808,   0,       69819,      32,
+    69821,  0,       69822,  32,      69826,   -69827,  69888,   0,        69891,   -69892,  69927,      0,
+    69941,  -69942,  69952,  32,      69956,   -69957,  70003,   0,        70004,   32,      70006,      -70007,
+    70016,  0,       70019,  -70020,  70067,   0,       70081,   -70082,   70085,   32,      70090,      0,
+    70093,  32,      70094,  -70095,  70107,   32,      70108,   70108,    70109,   32,      70112,      -70113,
+    70188,  0,       70200,  32,      70206,   0,       70207,   -70208,   70313,   32,      70314,      -70315,
+    70367,  0,       70379,  -70380,  70400,   0,       70404,   -70405,   70460,   0,       70461,      70461,
+    70462,  0,       70469,  -70470,  70471,   0,       70473,   -70474,   70475,   0,       70478,      -70479,
+    70487,  0,       70488,  -70489,  70498,   0,       70500,   -70501,   70502,   0,       70509,      -70510,
+    70512,  0,       70517,  -70518,  70709,   0,       70727,   -70728,   70731,   32,      70736,      -70737,
+    70747,  32,      70748,  70748,   70749,   32,      70750,   -70751,   70832,   0,       70852,      -70853,
+    70854,  32,      70855,  -70856,  71087,   0,       71094,   -71095,   71096,   0,       71105,      32,
+    71128,  -71129,  71132,  0,       71134,   -71135,  71216,   0,        71233,   32,      71236,      -71237,
+    71264,  32,      71277,  -71278,  71339,   0,       71352,   -71353,   71453,   0,       71468,      -71469,
+    71484,  32,      71488,  -71489,  71840,   -71873,  71872,   -71873,   72751,   0,       72759,      72759,
+    72760,  0,       72768,  72768,   72769,   32,      72774,   -72775,   72816,   32,      72818,      -72819,
+    72850,  0,       72872,  72872,   72873,   0,       72887,   -72888,   74864,   32,      74869,      -74870,
+    92782,  32,      92784,  -92785,  92912,   0,       92917,   32,       92918,   -92919,  92976,      0,
+    92983,  32,      92992,  -92993,  92996,   32,      92998,   -92999,   94033,   0,       94079,      -94080,
+    94095,  0,       94099,  -94100,  113820,  32,      113821,  0,        113823,  32,      113824,     0,
+    113828, -113829, 118784, 32,      119030,  -119031, 119040,  32,       119079,  -119080, 119081,     32,
+    119141, 0,       119146, 32,      119149,  0,       119171,  32,       119173,  0,       119180,     32,
+    119210, 0,       119214, 32,      119273,  -119274, 119296,  32,       119362,  0,       119365,     32,
+    119366, -119367, 119552, 32,      119639,  -119640, 119808,  -98,      119834,  -119835, 119860,     -98,
+    119886, -119887, 119912, -98,     119938,  -119939, 119964,  97,       119965,  119965,  119966,     -100,
+    119968, -119969, 119970, 103,     119971,  -119972, 119973,  -107,     119975,  -119976, 119977,     -111,
+    119981, 119981,  119982, -116,    119990,  -119991, 120016,  -98,      120042,  -120043, 120068,     -98,
+    120070, 120070,  120071, -101,    120075,  -120076, 120077,  -107,     120085,  120085,  120086,     -116,
+    120093, -120094, 120120, -98,     120122,  120122,  120123,  -101,     120127,  120127,  120128,     -106,
+    120133, 120133,  120134, 111,     120135,  -120136, 120138,  -116,     120145,  -120146, 120172,     -98,
+    120198, -120199, 120224, -98,     120250,  -120251, 120276,  -98,      120302,  -120303, 120328,     -98,
+    120354, -120355, 120380, -98,     120406,  -120407, 120432,  -98,      120458,  -120459, 120488,     -946,
+    120505, 952,     120506, -964,    120513,  32,      120514,  -120515,  120531,  963,     120532,     -120533,
+    120539, 32,      120540, -120541, 120546,  -946,    120563,  952,      120564,  -964,    120571,     32,
+    120572, -120573, 120589, 963,     120590,  -120591, 120597,  32,       120598,  -120599, 120604,     -946,
+    120621, 952,     120622, -964,    120629,  32,      120630,  -120631,  120647,  963,     120648,     -120649,
+    120655, 32,      120656, -120657, 120662,  -946,    120679,  952,      120680,  -964,    120687,     32,
+    120688, -120689, 120705, 963,     120706,  -120707, 120713,  32,       120714,  -120715, 120720,     -946,
+    120737, 952,     120738, -964,    120745,  32,      120746,  -120747,  120763,  963,     120764,     -120765,
+    120771, 32,      120772, -120773, 120778,  989,     120779,  -120780,  120832,  32,      121344,     0,
+    121399, 32,      121403, 0,       121453,  32,      121461,  0,        121462,  32,      121476,     0,
+    121477, 32,      121484, -121485, 121499,  0,       121504,  121504,   121505,  0,       121520,     -121521,
+    122880, 0,       122887, 122887,  122888,  0,       122905,  -122906,  122907,  0,       122914,     122914,
+    122915, 0,       122917, 122917,  122918,  0,       122923,  -122924,  125136,  0,       125143,     -125144,
+    125184, -125219, 125218, -125219, 125252,  0,       125259,  -125260,  125278,  32,      125280,     -125281,
+    126704, 32,      126706, -126707, 126976,  32,      127020,  -127021,  127024,  32,      127124,     -127125,
+    127136, 32,      127151, -127152, 127153,  32,      127168,  127168,   127169,  32,      127184,     127184,
+    127185, 32,      127222, -127223, 127248,  32,      127275,  99,       127276,  114,     127277,     32,
+    127279, 127279,  127280, -98,     127306,  32,      127340,  -127341,  127344,  32,      127405,     -127406,
+    127462, 32,      127490, -127491, 127552,  32,      127561,  -127562,  127744,  32,      128723,     -128724,
+    128736, 32,      128749, -128750, 128752,  32,      128759,  -128760,  128768,  32,      128884,     -128885,
+    128896, 32,      128981, -128982, 129024,  32,      129036,  -129037,  129040,  32,      129096,     -129097,
+    129104, 32,      129114, -129115, 129120,  32,      129160,  -129161,  129168,  32,      129198,     -129199,
+    129296, 32,      129311, 129311,  129312,  32,      129320,  -129321,  129328,  32,      129329,     -129330,
+    129331, 32,      129343, 129343,  129344,  32,      129356,  -129357,  129360,  32,      129375,     -129376,
+    129408, 32,      129426, -129427, 129472,  32,      129473,  -129474,  131070,  32,      131072,     -131073,
+    196606, 32,      196608, -196609, 262142,  32,      262144,  -262145,  327678,  32,      327680,     -327681,
+    393214, 32,      393216, -393217, 458750,  32,      458752,  -458753,  524286,  32,      524288,     -524289,
+    589822, 32,      589824, -589825, 655358,  32,      655360,  -655361,  720894,  32,      720896,     -720897,
+    786430, 32,      786432, -786433, 851966,  32,      851968,  -851969,  917502,  32,      917504,     917504,
+    917505, 0,       917506, -917507, 917536,  0,       917632,  -917633,  917760,  0,       918000,     -918001,
+    983038, 32,      983040, -983041, 1048574, 32,      1048576, -1048577, 1114110, 32,      2147483647, 0};
+
+static int16 to_lower_table[TABLE_SIZE] = {
+    0,     1,    2,    3,    4,     5,    6,    7,    8,    9,    10,   11,   12,   13,   14,   15,   16,   17,   18,
+    19,    20,   21,   22,   23,    24,   25,   26,   27,   28,   29,   30,   31,   32,   33,   34,   35,   36,   37,
+    38,    39,   40,   41,   42,    43,   44,   45,   46,   47,   48,   49,   50,   51,   52,   53,   54,   55,   56,
+    57,    58,   59,   60,   61,    62,   63,   64,   97,   98,   99,   100,  101,  102,  103,  104,  105,  106,  107,
+    108,   109,  110,  111,  112,   113,  114,  115,  116,  117,  118,  119,  120,  121,  122,  91,   92,   93,   94,
+    95,    96,   97,   98,   99,    100,  101,  102,  103,  104,  105,  106,  107,  108,  109,  110,  111,  112,  113,
+    114,   115,  116,  117,  118,   119,  120,  121,  122,  123,  124,  125,  126,  127,  128,  129,  130,  131,  132,
+    133,   134,  135,  136,  137,   138,  139,  140,  141,  142,  143,  144,  145,  146,  147,  148,  149,  150,  151,
+    152,   153,  154,  155,  156,   157,  158,  159,  160,  161,  162,  163,  164,  165,  166,  167,  168,  169,  170,
+    171,   172,  173,  174,  175,   176,  177,  178,  179,  180,  181,  182,  183,  184,  185,  186,  187,  188,  189,
+    190,   191,  224,  225,  226,   227,  228,  229,  230,  231,  232,  233,  234,  235,  236,  237,  238,  239,  240,
+    241,   242,  243,  244,  245,   246,  215,  248,  249,  250,  251,  252,  253,  254,  223,  224,  225,  226,  227,
+    228,   229,  230,  231,  232,   233,  234,  235,  236,  237,  238,  239,  240,  241,  242,  243,  244,  245,  246,
+    247,   248,  249,  250,  251,   252,  253,  254,  255,  257,  257,  259,  259,  261,  261,  263,  263,  265,  265,
+    267,   267,  269,  269,  271,   271,  273,  273,  275,  275,  277,  277,  279,  279,  281,  281,  283,  283,  285,
+    285,   287,  287,  289,  289,   291,  291,  293,  293,  295,  295,  297,  297,  299,  299,  301,  301,  303,  303,
+    105,   305,  307,  307,  309,   309,  311,  311,  312,  314,  314,  316,  316,  318,  318,  320,  320,  322,  322,
+    324,   324,  326,  326,  328,   328,  329,  331,  331,  333,  333,  335,  335,  337,  337,  339,  339,  341,  341,
+    343,   343,  345,  345,  347,   347,  349,  349,  351,  351,  353,  353,  355,  355,  357,  357,  359,  359,  361,
+    361,   363,  363,  365,  365,   367,  367,  369,  369,  371,  371,  373,  373,  375,  375,  255,  378,  378,  380,
+    380,   382,  382,  383,  384,   595,  387,  387,  389,  389,  596,  392,  392,  598,  599,  396,  396,  397,  477,
+    601,   603,  402,  402,  608,   611,  405,  617,  616,  409,  409,  410,  411,  623,  626,  414,  629,  417,  417,
+    419,   419,  421,  421,  640,   424,  424,  643,  426,  427,  429,  429,  648,  432,  432,  650,  651,  436,  436,
+    438,   438,  658,  441,  441,   442,  443,  445,  445,  446,  447,  448,  449,  450,  451,  454,  454,  454,  457,
+    457,   457,  460,  460,  460,   462,  462,  464,  464,  466,  466,  468,  468,  470,  470,  472,  472,  474,  474,
+    476,   476,  477,  479,  479,   481,  481,  483,  483,  485,  485,  487,  487,  489,  489,  491,  491,  493,  493,
+    495,   495,  496,  499,  499,   499,  501,  501,  405,  447,  505,  505,  507,  507,  509,  509,  511,  511,  513,
+    513,   515,  515,  517,  517,   519,  519,  521,  521,  523,  523,  525,  525,  527,  527,  529,  529,  531,  531,
+    533,   533,  535,  535,  537,   537,  539,  539,  541,  541,  543,  543,  414,  545,  547,  547,  549,  549,  551,
+    551,   553,  553,  555,  555,   557,  557,  559,  559,  561,  561,  563,  563,  564,  565,  566,  567,  568,  569,
+    11365, 572,  572,  410,  11366, 575,  576,  578,  578,  384,  649,  652,  583,  583,  585,  585,  587,  587,  589,
+    589,   591,  591,  592,  593,   594,  595,  596,  597,  598,  599,  600,  601,  602,  603,  604,  605,  606,  607,
+    608,   609,  610,  611,  612,   613,  614,  615,  616,  617,  618,  619,  620,  621,  622,  623,  624,  625,  626,
+    627,   628,  629,  630,  631,   632,  633,  634,  635,  636,  637,  638,  639,  640,  641,  642,  643,  644,  645,
+    646,   647,  648,  649,  650,   651,  652,  653,  654,  655,  656,  657,  658,  659,  660,  661,  662,  663,  664,
+    665,   666,  667,  668,  669,   670,  671,  672,  673,  674,  675,  676,  677,  678,  679,  680,  681,  682,  683,
+    684,   685,  686,  687,  688,   689,  690,  691,  692,  693,  694,  695,  696,  697,  698,  699,  700,  701,  702,
+    703,   704,  705,  706,  707,   708,  709,  710,  711,  712,  713,  714,  715,  716,  717,  718,  719,  720,  721,
+    722,   723,  724,  725,  726,   727,  728,  729,  730,  731,  732,  733,  734,  735,  736,  737,  738,  739,  740,
+    741,   742,  743,  744,  745,   746,  747,  748,  749,  750,  751,  752,  753,  754,  755,  756,  757,  758,  759,
+    760,   761,  762,  763,  764,   765,  766,  767,  768,  769,  770,  771,  772,  773,  774,  775,  776,  777,  778,
+    779,   780,  781,  782,  783,   784,  785,  786,  787,  788,  789,  790,  791,  792,  793,  794,  795,  796,  797,
+    798,   799,  800,  801,  802,   803,  804,  805,  806,  807,  808,  809,  810,  811,  812,  813,  814,  815,  816,
+    817,   818,  819,  820,  821,   822,  823,  824,  825,  826,  827,  828,  829,  830,  831,  832,  833,  834,  835,
+    836,   837,  838,  839,  840,   841,  842,  843,  844,  845,  846,  847,  848,  849,  850,  851,  852,  853,  854,
+    855,   856,  857,  858,  859,   860,  861,  862,  863,  864,  865,  866,  867,  868,  869,  870,  871,  872,  873,
+    874,   875,  876,  877,  878,   879,  881,  881,  883,  883,  884,  885,  887,  887,  888,  889,  890,  891,  892,
+    893,   894,  1011, 896,  897,   898,  899,  900,  901,  940,  903,  941,  942,  943,  907,  972,  909,  973,  974,
+    912,   945,  946,  947,  948,   949,  950,  951,  952,  953,  954,  955,  956,  957,  958,  959,  960,  961,  930,
+    963,   964,  965,  966,  967,   968,  969,  970,  971,  940,  941,  942,  943,  944,  945,  946,  947,  948,  949,
+    950,   951,  952,  953,  954,   955,  956,  957,  958,  959,  960,  961,  962,  963,  964,  965,  966,  967,  968,
+    969,   970,  971,  972,  973,   974,  983,  976,  977,  978,  979,  980,  981,  982,  983,  985,  985,  987,  987,
+    989,   989,  991,  991,  993,   993,  995,  995,  997,  997,  999,  999,  1001, 1001, 1003, 1003, 1005, 1005, 1007,
+    1007,  1008, 1009, 1010, 1011,  952,  1013, 1014, 1016, 1016, 1010, 1019, 1019, 1020, 891,  892,  893,  1104, 1105,
+    1106,  1107, 1108, 1109, 1110,  1111, 1112, 1113, 1114, 1115, 1116, 1117, 1118, 1119, 1072, 1073, 1074, 1075, 1076,
+    1077,  1078, 1079, 1080, 1081,  1082, 1083, 1084, 1085, 1086, 1087, 1088, 1089, 1090, 1091, 1092, 1093, 1094, 1095,
+    1096,  1097, 1098, 1099, 1100,  1101, 1102, 1103, 1072, 1073, 1074, 1075, 1076, 1077, 1078, 1079, 1080, 1081, 1082,
+    1083,  1084, 1085, 1086, 1087,  1088, 1089, 1090, 1091, 1092, 1093, 1094, 1095, 1096, 1097, 1098, 1099, 1100, 1101,
+    1102,  1103, 1104, 1105, 1106,  1107, 1108, 1109, 1110, 1111, 1112, 1113, 1114, 1115, 1116, 1117, 1118, 1119, 1121,
+    1121,  1123, 1123, 1125, 1125,  1127, 1127, 1129, 1129, 1131, 1131, 1133, 1133, 1135, 1135, 1137, 1137, 1139, 1139,
+    1141,  1141, 1143, 1143, 1145,  1145, 1147, 1147, 1149, 1149, 1151, 1151, 1153, 1153, 1154, 1155, 1156, 1157, 1158,
+    1159,  1160, 1161, 1163, 1163,  1165, 1165, 1167, 1167, 1169, 1169, 1171, 1171, 1173, 1173, 1175, 1175, 1177, 1177,
+    1179,  1179, 1181, 1181, 1183,  1183, 1185, 1185, 1187, 1187, 1189, 1189, 1191, 1191, 1193, 1193, 1195, 1195, 1197,
+    1197,  1199, 1199, 1201, 1201,  1203, 1203, 1205, 1205, 1207, 1207, 1209, 1209, 1211, 1211, 1213, 1213, 1215, 1215,
+    1231,  1218, 1218, 1220, 1220,  1222, 1222, 1224, 1224, 1226, 1226, 1228, 1228, 1230, 1230, 1231, 1233, 1233, 1235,
+    1235,  1237, 1237, 1239, 1239,  1241, 1241, 1243, 1243, 1245, 1245, 1247, 1247, 1249, 1249, 1251, 1251, 1253, 1253,
+    1255,  1255, 1257, 1257, 1259,  1259, 1261, 1261, 1263, 1263, 1265, 1265, 1267, 1267, 1269, 1269, 1271, 1271, 1273,
+    1273,  1275, 1275, 1277, 1277,  1279, 1279};
+
+static const int32 to_lower_ranges[] = {
+    1280,   2097153, 1328,       1328,    1329,    -1378,   1367,   -1368,   4256,    -11521, 4294,    4294,   4295,
+    11559,  4296,    -4297,      4301,    11565,   4302,    -4303,  5024,    -43889,  5104,   -5113,   5110,   -5111,
+    7680,   2097153, 7830,       -7831,   7838,    223,     7839,   2097153, 7936,    -7937,  7944,    -7937,  7952,
+    -7953,  7960,    -7953,      7966,    -7967,   7976,    -7969,  7984,    -7985,   7992,   -7985,   8000,   -8001,
+    8008,   -8001,   8014,       -8015,   8025,    8017,    8026,   8026,    8027,    8019,   8028,    8028,   8029,
+    8021,   8030,    8030,       8031,    8023,    8032,    -8033,  8040,    -8033,   8048,   -8049,   8072,   -8065,
+    8080,   -8081,   8088,       -8081,   8096,    -8097,   8104,   -8097,   8112,    -8113,  8120,    -8113,  8122,
+    -8049,  8124,    8115,       8125,    -8126,   8136,    -8051,  8140,    8131,    8141,   -8142,   8152,   -8145,
+    8154,   -8055,   8156,       -8157,   8168,    -8161,   8170,   -8059,   8172,    8165,   8173,    -8174,  8184,
+    -8057,  8186,    -8061,      8188,    8179,    8189,    -8190,  8486,    969,     8487,   -8488,   8490,   107,
+    8491,   229,     8492,       -8493,   8498,    8526,    8499,   -8500,   8544,    -8561,  8560,    -8561,  8579,
+    8580,   8581,    -8582,      9398,    -9425,   9424,    -9425,  11264,   -11313,  11311,  -11312,  11360,  11361,
+    11362,  619,     11363,      7549,    11364,   637,     11365,  -11366,  11367,   11368,  11369,   11370,  11371,
+    11372,  11373,   593,        11374,   625,     11375,   592,    11376,   594,     11377,  2097153, 11380,  11380,
+    11381,  11382,   11383,      -11384,  11390,   -576,    11392,  2097153, 11492,   -11493, 11499,   11500,  11501,
+    11502,  11503,   -11504,     11506,   11507,   11508,   -11509, 42560,   2097153, 42606,  -42607,  42624,  2097153,
+    42652,  -42653,  42786,      2097153, 42800,   -42801,  42802,  2097153, 42864,   -42865, 42873,   42874,  42875,
+    42876,  42877,   7545,       42878,   2097153, 42888,   -42889, 42891,   42892,   42893,  613,     42894,  -42895,
+    42896,  2097153, 42900,      -42901,  42902,   2097153, 42922,  614,     42923,   604,    42924,   609,    42925,
+    620,    42926,   618,        42927,   42927,   42928,   670,    42929,   647,     42930,  669,     42931,  43859,
+    42932,  2097153, 42936,      -42937,  65313,   -65346,  65339,  -65340,  66560,   -66601, 66600,   -66601, 66736,
+    -66777, 66772,   -66773,     68736,   -68801,  68787,   -68788, 71840,   -71873,  71872,  -71873,  125184, -125219,
+    125218, -125219, 2147483647, 0};
+
+UnicodeSimpleCategory get_unicode_simple_category(uint32 code) {
+  auto it = std::upper_bound(std::begin(unicode_simple_category_ranges), std::end(unicode_simple_category_ranges),
+                             (code << 5) + 30);
+  return static_cast<UnicodeSimpleCategory>(*(it - 1) & 31);
+}
+
+/**
+ * Search pregenerated ranges of pairs for the replacement of specified character
+ */
+template <size_t N>
+static uint32 binary_search_ranges(const int32 (&ranges)[N], uint32 code) {
+  if (code > 0x10ffff) {
+    return 0;
+  }
+
+  int32 code_int = static_cast<int32>(code);
+  size_t l = 0, r = N;
+  while (l < r) {
+    size_t m = ((l + r + 2) >> 2) << 1;
+    if (ranges[m] <= code_int) {
+      l = m;
+    } else {
+      r = m - 2;
+    }
+  }
+
+  int32 t = ranges[l + 1];
+  if (t < 0) {
+    return code - ranges[l] + (~t);
+  }
+  if (t <= 0x10ffff) {
+    return t;
+  }
+  switch (t - 0x200000) {
+    case 0:
+      return (code & -2);
+    case 1:
+      return (code | 1);
+    case 2:
+      return ((code - 1) | 1);
+    default:
+      UNREACHABLE();
+      return 0;
+  }
+}
+
+uint32 prepare_search_character(uint32 code) {
+  if (code < TABLE_SIZE) {
+    return prepare_search_character_table[code];
+  } else {
+    return binary_search_ranges(prepare_search_character_ranges, code);
+  }
+}
+
+uint32 unicode_to_lower(uint32 code) {
+  if (code < TABLE_SIZE) {
+    return to_lower_table[code];
+  } else {
+    return binary_search_ranges(to_lower_ranges, code);
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/unicode.h b/libs/tdlib/td/tdutils/td/utils/unicode.h
new file mode 100644
index 0000000000..1c75397d6e
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/unicode.h
@@ -0,0 +1,28 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+namespace td {
+
+enum class UnicodeSimpleCategory { Unknown, Letter, DecimalNumber, Number, Separator };
+
+UnicodeSimpleCategory get_unicode_simple_category(uint32 code);
+
+/**
+ * Prepares unicode character for search, leaving only digits and lowercased letters.
+ * Return code of replacing character or 0 if the character should be skipped.
+ */
+uint32 prepare_search_character(uint32 code);
+
+/**
+ * Converts unicode character to lower case.
+ */
+uint32 unicode_to_lower(uint32 code);
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/utf8.cpp b/libs/tdlib/td/tdutils/td/utils/utf8.cpp
new file mode 100644
index 0000000000..50f82d6393
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/utf8.cpp
@@ -0,0 +1,124 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/utf8.h"
+
+#include "td/utils/logging.h"  // for UNREACHABLE
+#include "td/utils/unicode.h"
+
+namespace td {
+
+bool check_utf8(CSlice str) {
+  const char *data = str.data();
+  const char *data_end = data + str.size();
+  do {
+    unsigned int a = static_cast<unsigned char>(*data++);
+    if ((a & 0x80) == 0) {
+      if (data == data_end + 1) {
+        return true;
+      }
+      continue;
+    }
+
+#define ENSURE(condition) \
+  if (!(condition)) {     \
+    return false;         \
+  }
+
+    ENSURE((a & 0x40) != 0);
+
+    unsigned int b = static_cast<unsigned char>(*data++);
+    ENSURE((b & 0xc0) == 0x80);
+    if ((a & 0x20) == 0) {
+      ENSURE((a & 0x1e) > 0);
+      continue;
+    }
+
+    unsigned int c = static_cast<unsigned char>(*data++);
+    ENSURE((c & 0xc0) == 0x80);
+    if ((a & 0x10) == 0) {
+      int x = (((a & 0x0f) << 6) | (b & 0x20));
+      ENSURE(x != 0 && x != 0x360);  // surrogates
+      continue;
+    }
+
+    unsigned int d = static_cast<unsigned char>(*data++);
+    ENSURE((d & 0xc0) == 0x80);
+    if ((a & 0x08) == 0) {
+      int t = (((a & 0x07) << 6) | (b & 0x30));
+      ENSURE(0 < t && t < 0x110);  // end of unicode
+      continue;
+    }
+
+    return false;
+#undef ENSURE
+  } while (true);
+
+  UNREACHABLE();
+  return false;
+}
+
+void append_utf8_character(string &str, uint32 ch) {
+  if (ch <= 0x7f) {
+    str.push_back(static_cast<char>(ch));
+  } else if (ch <= 0x7ff) {
+    str.push_back(static_cast<char>(0xc0 | (ch >> 6)));  // implementation-defined
+    str.push_back(static_cast<char>(0x80 | (ch & 0x3f)));
+  } else if (ch <= 0xffff) {
+    str.push_back(static_cast<char>(0xe0 | (ch >> 12)));  // implementation-defined
+    str.push_back(static_cast<char>(0x80 | ((ch >> 6) & 0x3f)));
+    str.push_back(static_cast<char>(0x80 | (ch & 0x3f)));
+  } else {
+    str.push_back(static_cast<char>(0xf0 | (ch >> 18)));  // implementation-defined
+    str.push_back(static_cast<char>(0x80 | ((ch >> 12) & 0x3f)));
+    str.push_back(static_cast<char>(0x80 | ((ch >> 6) & 0x3f)));
+    str.push_back(static_cast<char>(0x80 | (ch & 0x3f)));
+  }
+}
+
+const unsigned char *next_utf8_unsafe(const unsigned char *ptr, uint32 *code) {
+  uint32 a = ptr[0];
+  if ((a & 0x80) == 0) {
+    if (code) {
+      *code = a;
+    }
+    return ptr + 1;
+  } else if ((a & 0x20) == 0) {
+    if (code) {
+      *code = ((a & 0x1f) << 6) | (ptr[1] & 0x3f);
+    }
+    return ptr + 2;
+  } else if ((a & 0x10) == 0) {
+    if (code) {
+      *code = ((a & 0x0f) << 12) | ((ptr[1] & 0x3f) << 6) | (ptr[2] & 0x3f);
+    }
+    return ptr + 3;
+  } else if ((a & 0x08) == 0) {
+    if (code) {
+      *code = ((a & 0x07) << 18) | ((ptr[1] & 0x3f) << 12) | ((ptr[2] & 0x3f) << 6) | (ptr[3] & 0x3f);
+    }
+    return ptr + 4;
+  }
+  UNREACHABLE();
+  if (code) {
+    *code = 0;
+  }
+  return ptr;
+}
+
+string utf8_to_lower(Slice str) {
+  string result;
+  auto pos = str.ubegin();
+  auto end = str.uend();
+  while (pos != end) {
+    uint32 code;
+    pos = next_utf8_unsafe(pos, &code);
+    append_utf8_character(result, unicode_to_lower(code));
+  }
+  return result;
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/td/utils/utf8.h b/libs/tdlib/td/tdutils/td/utils/utf8.h
new file mode 100644
index 0000000000..6be1952c19
--- /dev/null
+++ b/libs/tdlib/td/tdutils/td/utils/utf8.h
@@ -0,0 +1,106 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/int_types.h"
+#include "td/utils/Slice.h"
+
+namespace td {
+
+/// checks UTF-8 string for correctness
+bool check_utf8(CSlice str);
+
+/// checks if a code unit is a first code unit of a UTF-8 character
+inline bool is_utf8_character_first_code_unit(unsigned char c) {
+  return (c & 0xC0) != 0x80;
+}
+
+/// returns length of UTF-8 string in characters
+inline size_t utf8_length(Slice str) {
+  size_t result = 0;
+  for (auto c : str) {
+    result += is_utf8_character_first_code_unit(c);
+  }
+  return result;
+}
+
+/// appends a Unicode character using UTF-8 encoding
+void append_utf8_character(string &str, uint32 ch);
+
+/// moves pointer one UTF-8 character back
+inline const unsigned char *prev_utf8_unsafe(const unsigned char *ptr) {
+  while (!is_utf8_character_first_code_unit(*--ptr)) {
+    // pass
+  }
+  return ptr;
+}
+
+/// moves pointer one UTF-8 character forward and saves code of the skipped character in *code
+const unsigned char *next_utf8_unsafe(const unsigned char *ptr, uint32 *code);
+
+/// truncates UTF-8 string to the given length in Unicode characters
+template <class T>
+T utf8_truncate(T str, size_t length) {
+  if (str.size() > length) {
+    for (size_t i = 0; i < str.size(); i++) {
+      if (is_utf8_character_first_code_unit(static_cast<unsigned char>(str[i]))) {
+        if (length == 0) {
+          return str.substr(0, i);
+        } else {
+          length--;
+        }
+      }
+    }
+  }
+  return str;
+}
+
+/// truncates UTF-8 string to the given length given in UTF-16 code units
+template <class T>
+T utf8_utf16_truncate(T str, size_t length) {
+  for (size_t i = 0; i < str.size(); i++) {
+    auto c = static_cast<unsigned char>(str[i]);
+    if (is_utf8_character_first_code_unit(c)) {
+      if (length <= 0) {
+        return str.substr(0, i);
+      } else {
+        length--;
+        if (c >= 0xf0) {  // >= 4 bytes in symbol => surrogaite pair
+          length--;
+        }
+      }
+    }
+  }
+  return str;
+}
+
+template <class T>
+T utf8_substr(T str, size_t offset) {
+  auto offset_pos = utf8_truncate(str, offset).size();
+  return str.substr(offset_pos);
+}
+
+template <class T>
+T utf8_substr(T str, size_t offset, size_t length) {
+  return utf8_truncate(utf8_substr(str, offset), length);
+}
+
+template <class T>
+T utf8_utf16_substr(T str, size_t offset) {
+  auto offset_pos = utf8_utf16_truncate(str, offset).size();
+  return str.substr(offset_pos);
+}
+
+template <class T>
+T utf8_utf16_substr(T str, size_t offset, size_t length) {
+  return utf8_utf16_truncate(utf8_utf16_substr(str, offset), length);
+}
+
+/// Returns UTF-8 string converted to lower case.
+string utf8_to_lower(Slice str);
+
+}  // namespace td
diff --git a/libs/tdlib/td/tdutils/test/Enumerator.cpp b/libs/tdlib/td/tdutils/test/Enumerator.cpp
new file mode 100644
index 0000000000..b617485462
--- /dev/null
+++ b/libs/tdlib/td/tdutils/test/Enumerator.cpp
@@ -0,0 +1,24 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/Enumerator.h"
+#include "td/utils/tests.h"
+
+TEST(Enumerator, simple) {
+  td::Enumerator<std::string> e;
+  auto b = e.add("b");
+  auto a = e.add("a");
+  auto d = e.add("d");
+  auto c = e.add("c");
+  ASSERT_STREQ(e.get(a), "a");
+  ASSERT_STREQ(e.get(b), "b");
+  ASSERT_STREQ(e.get(c), "c");
+  ASSERT_STREQ(e.get(d), "d");
+  ASSERT_EQ(a, e.add("a"));
+  ASSERT_EQ(b, e.add("b"));
+  ASSERT_EQ(c, e.add("c"));
+  ASSERT_EQ(d, e.add("d"));
+}
diff --git a/libs/tdlib/td/tdutils/test/HazardPointers.cpp b/libs/tdlib/td/tdutils/test/HazardPointers.cpp
new file mode 100644
index 0000000000..36b0570530
--- /dev/null
+++ b/libs/tdlib/td/tdutils/test/HazardPointers.cpp
@@ -0,0 +1,58 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/HazardPointers.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/thread.h"
+#include "td/utils/Random.h"
+#include "td/utils/tests.h"
+
+#include <atomic>
+
+#if !TD_THREAD_UNSUPPORTED
+TEST(HazardPointers, stress) {
+  struct Node {
+    std::atomic<std::string *> name_;
+    char pad[64];
+  };
+  int threads_n = 10;
+  std::vector<Node> nodes(threads_n);
+  td::HazardPointers<std::string> hazard_pointers(threads_n);
+  std::vector<td::thread> threads(threads_n);
+  int thread_id = 0;
+  for (auto &thread : threads) {
+    thread = td::thread([&, thread_id] {
+      auto holder = hazard_pointers.get_holder(thread_id, 0);
+      for (int i = 0; i < 1000000; i++) {
+        auto &node = nodes[td::Random::fast(0, threads_n - 1)];
+        auto *str = holder.protect(node.name_);
+        if (str) {
+          CHECK(*str == "one" || *str == "twotwo");
+        }
+        holder.clear();
+        if (td::Random::fast(0, 5) == 0) {
+          std::string *new_str = new std::string(td::Random::fast(0, 1) == 0 ? "one" : "twotwo");
+          if (node.name_.compare_exchange_strong(str, new_str, std::memory_order_acq_rel)) {
+            hazard_pointers.retire(thread_id, str);
+          } else {
+            delete new_str;
+          }
+        }
+      }
+    });
+    thread_id++;
+  }
+  for (auto &thread : threads) {
+    thread.join();
+  }
+  LOG(ERROR) << "Undeleted pointers: " << hazard_pointers.to_delete_size_unsafe();
+  CHECK(static_cast<int>(hazard_pointers.to_delete_size_unsafe()) <= threads_n * threads_n);
+  for (int i = 0; i < threads_n; i++) {
+    hazard_pointers.retire(i);
+  }
+  CHECK(hazard_pointers.to_delete_size_unsafe() == 0);
+}
+#endif  //!TD_THREAD_UNSUPPORTED
diff --git a/libs/tdlib/td/tdutils/test/MpmcQueue.cpp b/libs/tdlib/td/tdutils/test/MpmcQueue.cpp
new file mode 100644
index 0000000000..2da3f0cd3f
--- /dev/null
+++ b/libs/tdlib/td/tdutils/test/MpmcQueue.cpp
@@ -0,0 +1,205 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/logging.h"
+#include "td/utils/MpmcQueue.h"
+#include "td/utils/port/thread.h"
+#include "td/utils/tests.h"
+
+#include <algorithm>
+#include <tuple>
+
+TEST(OneValue, simple) {
+  {
+    std::string x{"hello"};
+    td::OneValue<std::string> value;
+    auto status = value.set_value(x);
+    CHECK(status);
+    CHECK(x.empty());
+    status = value.get_value(x);
+    CHECK(status);
+    CHECK(x == "hello");
+  }
+  {
+    td::OneValue<std::string> value;
+    std::string x;
+    auto status = value.get_value(x);
+    CHECK(!status);
+    CHECK(x.empty());
+    std::string y{"hello"};
+    status = value.set_value(y);
+    CHECK(!status);
+    CHECK(y == "hello");
+  }
+}
+
+#if !TD_THREAD_UNSUPPORTED
+TEST(OneValue, stress) {
+  td::Stage run;
+  td::Stage check;
+
+  std::string from;
+  bool set_status;
+
+  std::string to;
+  bool get_status;
+  std::vector<td::thread> threads;
+  td::OneValue<std::string> value;
+  for (size_t i = 0; i < 2; i++) {
+    threads.push_back(td::thread([&, id = i] {
+      for (td::uint64 round = 1; round < 100000; round++) {
+        if (id == 0) {
+          value.reset();
+          to = "";
+          from = "";
+        }
+        run.wait(round * 2);
+        if (id == 0) {
+          from = "hello";
+          set_status = value.set_value(from);
+        } else {
+          get_status = value.get_value(to);
+        }
+        check.wait(round * 2);
+        if (id == 0) {
+          if (set_status) {
+            CHECK(get_status);
+            CHECK(from.empty());
+            CHECK(to == "hello") << to;
+          } else {
+            CHECK(!get_status);
+            CHECK(from == "hello");
+            CHECK(to.empty());
+          }
+        }
+      }
+    }));
+  }
+  for (auto &thread : threads) {
+    thread.join();
+  }
+}
+#endif  //!TD_THREAD_UNSUPPORTED
+
+TEST(MpmcQueueBlock, simple) {
+  // Test doesn't work now and it is ok, try_pop, logic changed
+  return;
+  td::MpmcQueueBlock<std::string> block(2);
+  std::string x = "hello";
+  using PushStatus = td::MpmcQueueBlock<std::string>::PushStatus;
+  using PopStatus = td::MpmcQueueBlock<std::string>::PopStatus;
+  auto push_status = block.push(x);
+  CHECK(push_status == PushStatus::Ok);
+  CHECK(x.empty());
+  auto pop_status = block.pop(x);
+  CHECK(pop_status == PopStatus::Ok);
+  CHECK(x == "hello");
+  pop_status = block.try_pop(x);
+  CHECK(pop_status == PopStatus::Empty);
+  x = "hello";
+  push_status = block.push(x);
+  CHECK(push_status == PushStatus::Ok);
+  x = "hello";
+  push_status = block.push(x);
+  CHECK(push_status == PushStatus::Closed);
+  CHECK(x == "hello");
+  x = "";
+  pop_status = block.try_pop(x);
+  CHECK(pop_status == PopStatus::Ok);
+  pop_status = block.try_pop(x);
+  CHECK(pop_status == PopStatus::Closed);
+}
+
+TEST(MpmcQueue, simple) {
+  td::MpmcQueue<int> q(2, 1);
+  for (int t = 0; t < 2; t++) {
+    for (int i = 0; i < 100; i++) {
+      q.push(i, 0);
+    }
+    for (int i = 0; i < 100; i++) {
+      int x = q.pop(0);
+      CHECK(x == i) << x << " expected " << i;
+    }
+  }
+}
+
+#if !TD_THREAD_UNSUPPORTED
+TEST(MpmcQueue, multi_thread) {
+  size_t n = 10;
+  size_t m = 10;
+  struct Data {
+    size_t from{0};
+    size_t value{0};
+  };
+  struct ThreadData {
+    std::vector<Data> v;
+    char pad[64];
+  };
+  td::MpmcQueue<Data> q(1024, n + m + 1);
+  std::vector<td::thread> n_threads(n);
+  std::vector<td::thread> m_threads(m);
+  std::vector<ThreadData> thread_data(m);
+  size_t thread_id = 0;
+  for (auto &thread : m_threads) {
+    thread = td::thread([&, thread_id] {
+      while (true) {
+        auto data = q.pop(thread_id);
+        if (data.value == 0) {
+          return;
+        }
+        thread_data[thread_id].v.push_back(data);
+      }
+    });
+    thread_id++;
+  }
+  size_t qn = 100000;
+  for (auto &thread : n_threads) {
+    thread = td::thread([&, thread_id] {
+      for (size_t i = 0; i < qn; i++) {
+        Data data;
+        data.from = thread_id - m;
+        data.value = i + 1;
+        q.push(data, thread_id);
+      }
+    });
+    thread_id++;
+  }
+  for (auto &thread : n_threads) {
+    thread.join();
+  }
+  for (size_t i = 0; i < m; i++) {
+    Data data;
+    data.from = 0;
+    data.value = 0;
+    q.push(data, thread_id);
+  }
+  for (auto &thread : m_threads) {
+    thread.join();
+  }
+  std::vector<Data> all;
+  for (size_t i = 0; i < m; i++) {
+    std::vector<size_t> from(n, 0);
+    for (auto &data : thread_data[i].v) {
+      all.push_back(data);
+      CHECK(data.value > from[data.from]);
+      from[data.from] = data.value;
+    }
+  }
+  CHECK(all.size() == n * qn) << all.size();
+  std::sort(all.begin(), all.end(),
+            [](const auto &a, const auto &b) { return std::tie(a.from, a.value) < std::tie(b.from, b.value); });
+  for (size_t i = 0; i < n * qn; i++) {
+    CHECK(all[i].from == i / qn);
+    CHECK(all[i].value == i % qn + 1);
+  }
+  LOG(ERROR) << "Undeleted pointers: " << q.hazard_pointers_to_delele_size_unsafe();
+  CHECK(q.hazard_pointers_to_delele_size_unsafe() <= (n + m + 1) * (n + m + 1));
+  for (size_t id = 0; id < n + m + 1; id++) {
+    q.gc(id);
+  }
+  CHECK(q.hazard_pointers_to_delele_size_unsafe() == 0) << q.hazard_pointers_to_delele_size_unsafe();
+}
+#endif  //!TD_THREAD_UNSUPPORTED
diff --git a/libs/tdlib/td/tdutils/test/MpmcWaiter.cpp b/libs/tdlib/td/tdutils/test/MpmcWaiter.cpp
new file mode 100644
index 0000000000..e27e217713
--- /dev/null
+++ b/libs/tdlib/td/tdutils/test/MpmcWaiter.cpp
@@ -0,0 +1,117 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/MpmcWaiter.h"
+#include "td/utils/port/sleep.h"
+#include "td/utils/port/thread.h"
+#include "td/utils/Random.h"
+#include "td/utils/tests.h"
+
+#include <atomic>
+
+#if !TD_THREAD_UNSUPPORTED
+TEST(MpmcWaiter, stress_one_one) {
+  td::Stage run;
+  td::Stage check;
+
+  std::vector<td::thread> threads;
+  std::atomic<size_t> value;
+  size_t write_cnt = 10;
+  std::unique_ptr<td::MpmcWaiter> waiter;
+  size_t threads_n = 2;
+  for (size_t i = 0; i < threads_n; i++) {
+    threads.push_back(td::thread([&, id = static_cast<td::uint32>(i)] {
+      for (td::uint64 round = 1; round < 100000; round++) {
+        if (id == 0) {
+          value = 0;
+          waiter = std::make_unique<td::MpmcWaiter>();
+          write_cnt = td::Random::fast(1, 10);
+        }
+        run.wait(round * threads_n);
+        if (id == 1) {
+          for (size_t i = 0; i < write_cnt; i++) {
+            value.store(i + 1, std::memory_order_relaxed);
+            waiter->notify();
+          }
+        } else {
+          int yields = 0;
+          for (size_t i = 1; i <= write_cnt; i++) {
+            while (true) {
+              auto x = value.load(std::memory_order_relaxed);
+              if (x >= i) {
+                break;
+              }
+              yields = waiter->wait(yields, id);
+            }
+            yields = waiter->stop_wait(yields, id);
+          }
+        }
+        check.wait(round * threads_n);
+      }
+    }));
+  }
+  for (auto &thread : threads) {
+    thread.join();
+  }
+}
+TEST(MpmcWaiter, stress) {
+  td::Stage run;
+  td::Stage check;
+
+  std::vector<td::thread> threads;
+  size_t write_n;
+  size_t read_n;
+  std::atomic<size_t> write_pos;
+  std::atomic<size_t> read_pos;
+  size_t end_pos;
+  size_t write_cnt;
+  size_t threads_n = 20;
+  std::unique_ptr<td::MpmcWaiter> waiter;
+  for (size_t i = 0; i < threads_n; i++) {
+    threads.push_back(td::thread([&, id = static_cast<td::uint32>(i)] {
+      for (td::uint64 round = 1; round < 1000; round++) {
+        if (id == 0) {
+          write_n = td::Random::fast(1, 10);
+          read_n = td::Random::fast(1, 10);
+          write_cnt = td::Random::fast(1, 50);
+          end_pos = write_n * write_cnt;
+          write_pos = 0;
+          read_pos = 0;
+          waiter = std::make_unique<td::MpmcWaiter>();
+        }
+        run.wait(round * threads_n);
+        if (id <= write_n) {
+          for (size_t i = 0; i < write_cnt; i++) {
+            if (td::Random::fast(0, 20) == 0) {
+              td::usleep_for(td::Random::fast(1, 300));
+            }
+            write_pos.fetch_add(1, std::memory_order_relaxed);
+            waiter->notify();
+          }
+        } else if (id > 10 && id - 10 <= read_n) {
+          int yields = 0;
+          while (true) {
+            auto x = read_pos.load(std::memory_order_relaxed);
+            if (x == end_pos) {
+              break;
+            }
+            if (x == write_pos.load(std::memory_order_relaxed)) {
+              yields = waiter->wait(yields, id);
+              continue;
+            }
+            yields = waiter->stop_wait(yields, id);
+            read_pos.compare_exchange_strong(x, x + 1, std::memory_order_relaxed);
+          }
+        }
+        check.wait(round * threads_n);
+      }
+    }));
+  }
+  for (auto &thread : threads) {
+    thread.join();
+  }
+}
+#endif  // !TD_THREAD_UNSUPPORTED
diff --git a/libs/tdlib/td/tdutils/test/MpscLinkQueue.cpp b/libs/tdlib/td/tdutils/test/MpscLinkQueue.cpp
new file mode 100644
index 0000000000..629e5b7223
--- /dev/null
+++ b/libs/tdlib/td/tdutils/test/MpscLinkQueue.cpp
@@ -0,0 +1,115 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/MpscLinkQueue.h"
+#include "td/utils/port/thread.h"
+#include "td/utils/tests.h"
+
+class NodeX : public td::MpscLinkQueueImpl::Node {
+ public:
+  explicit NodeX(int value) : value_(value) {
+  }
+  td::MpscLinkQueueImpl::Node *to_mpsc_link_queue_node() {
+    return static_cast<td::MpscLinkQueueImpl::Node *>(this);
+  }
+  static NodeX *from_mpsc_link_queue_node(td::MpscLinkQueueImpl::Node *node) {
+    return static_cast<NodeX *>(node);
+  }
+  int value() {
+    return value_;
+  }
+
+ private:
+  int value_;
+};
+using QueueNode = td::MpscLinkQueueUniquePtrNode<NodeX>;
+
+QueueNode create_node(int value) {
+  return QueueNode(std::make_unique<NodeX>(value));
+}
+
+TEST(MpscLinkQueue, one_thread) {
+  td::MpscLinkQueue<QueueNode> queue;
+
+  {
+    queue.push(create_node(1));
+    queue.push(create_node(2));
+    queue.push(create_node(3));
+    td::MpscLinkQueue<QueueNode>::Reader reader;
+    queue.pop_all(reader);
+    queue.push(create_node(4));
+    queue.pop_all(reader);
+    std::vector<int> v;
+    while (auto node = reader.read()) {
+      v.push_back(node.value().value());
+    }
+    CHECK((v == std::vector<int>{1, 2, 3, 4})) << td::format::as_array(v);
+
+    v.clear();
+    queue.push(create_node(5));
+    queue.pop_all(reader);
+    while (auto node = reader.read()) {
+      v.push_back(node.value().value());
+    }
+    CHECK((v == std::vector<int>{5})) << td::format::as_array(v);
+  }
+
+  {
+    queue.push_unsafe(create_node(3));
+    queue.push_unsafe(create_node(2));
+    queue.push_unsafe(create_node(1));
+    queue.push_unsafe(create_node(0));
+    td::MpscLinkQueue<QueueNode>::Reader reader;
+    queue.pop_all_unsafe(reader);
+    std::vector<int> v;
+    while (auto node = reader.read()) {
+      v.push_back(node.value().value());
+    }
+    CHECK((v == std::vector<int>{3, 2, 1, 0})) << td::format::as_array(v);
+  }
+}
+
+#if !TD_THREAD_UNSUPPORTED
+TEST(MpscLinkQueue, multi_thread) {
+  td::MpscLinkQueue<QueueNode> queue;
+  int threads_n = 10;
+  int queries_n = 1000000;
+  std::vector<int> next_value(threads_n);
+  std::vector<td::thread> threads(threads_n);
+  int thread_i = 0;
+  for (auto &thread : threads) {
+    thread = td::thread([&, id = thread_i] {
+      for (int i = 0; i < queries_n; i++) {
+        queue.push(create_node(i * threads_n + id));
+      }
+    });
+    thread_i++;
+  }
+
+  int active_threads = threads_n;
+
+  td::MpscLinkQueue<QueueNode>::Reader reader;
+  while (active_threads) {
+    queue.pop_all(reader);
+    while (auto value = reader.read()) {
+      auto x = value.value().value();
+      auto thread_id = x % threads_n;
+      x /= threads_n;
+      CHECK(next_value[thread_id] == x);
+      next_value[thread_id]++;
+      if (x + 1 == queries_n) {
+        active_threads--;
+      }
+    }
+  }
+
+  for (auto &thread : threads) {
+    thread.join();
+  }
+}
+#endif  //!TD_THREAD_UNSUPPORTED
diff --git a/libs/tdlib/td/tdutils/test/OrderedEventsProcessor.cpp b/libs/tdlib/td/tdutils/test/OrderedEventsProcessor.cpp
new file mode 100644
index 0000000000..6a5a20015f
--- /dev/null
+++ b/libs/tdlib/td/tdutils/test/OrderedEventsProcessor.cpp
@@ -0,0 +1,36 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/OrderedEventsProcessor.h"
+#include "td/utils/Random.h"
+#include "td/utils/tests.h"
+
+#include <algorithm>
+#include <utility>
+#include <vector>
+
+TEST(OrderedEventsProcessor, random) {
+  int d = 5001;
+  int n = 1000000;
+  int offset = 1000000;
+  std::vector<std::pair<int, int>> v;
+  for (int i = 0; i < n; i++) {
+    auto shift = td::Random::fast(0, 1) ? td::Random::fast(0, d) : td::Random::fast(0, 1) * d;
+    v.push_back({i + shift, i + offset});
+  }
+  std::sort(v.begin(), v.end());
+
+  td::OrderedEventsProcessor<int> processor(offset);
+  int next_pos = offset;
+  for (auto p : v) {
+    int seq_no = p.second;
+    processor.add(seq_no, seq_no, [&](auto seq_no, int x) {
+      ASSERT_EQ(x, next_pos);
+      next_pos++;
+    });
+  }
+  ASSERT_EQ(next_pos, n + offset);
+}
diff --git a/libs/tdlib/td/tdutils/test/SharedObjectPool.cpp b/libs/tdlib/td/tdutils/test/SharedObjectPool.cpp
new file mode 100644
index 0000000000..61d956f4e6
--- /dev/null
+++ b/libs/tdlib/td/tdutils/test/SharedObjectPool.cpp
@@ -0,0 +1,96 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/logging.h"
+#include "td/utils/SharedObjectPool.h"
+#include "td/utils/tests.h"
+
+#include <memory>
+
+TEST(AtomicRefCnt, simple) {
+  td::detail::AtomicRefCnt cnt{0};
+  cnt.inc();
+  cnt.inc();
+  CHECK(!cnt.dec());
+  cnt.inc();
+  CHECK(!cnt.dec());
+  CHECK(cnt.dec());
+  cnt.inc();
+  CHECK(cnt.dec());
+}
+
+template <class T, class D>
+using Ptr = td::detail::SharedPtr<T, D>;
+class Deleter {
+ public:
+  template <class T>
+  void operator()(T *t) {
+    std::default_delete<T>()(t);
+    was_delete() = true;
+  }
+  static bool &was_delete() {
+    static bool flag = false;
+    return flag;
+  }
+};
+
+TEST(SharedPtr, simple) {
+  CHECK(!Deleter::was_delete());
+  Ptr<std::string, Deleter> ptr = Ptr<std::string, Deleter>::create("hello");
+  auto ptr2 = ptr;
+  CHECK(*ptr == "hello");
+  CHECK(*ptr2 == "hello");
+  ptr.reset();
+  CHECK(*ptr2 == "hello");
+  CHECK(ptr.empty());
+  Ptr<std::string, Deleter> ptr3 = std::move(ptr2);
+  CHECK(ptr2.empty());
+  CHECK(*ptr3 == "hello");
+  ptr = ptr3;
+  CHECK(*ptr3 == "hello");
+  ptr3.reset();
+  CHECK(*ptr == "hello");
+  ptr2 = std::move(ptr);
+  CHECK(ptr.empty());
+  CHECK(*ptr2 == "hello");
+  ptr2 = ptr2;
+  CHECK(*ptr2 == "hello");
+  CHECK(!Deleter::was_delete());
+  ptr2.reset();
+  CHECK(Deleter::was_delete());
+  CHECK(ptr2.empty());
+}
+
+TEST(SharedObjectPool, simple) {
+  class Node {
+   public:
+    Node() {
+      cnt()++;
+    };
+    ~Node() {
+      cnt()--;
+    }
+    static int &cnt() {
+      static int cnt_ = 0;
+      return cnt_;
+    }
+  };
+  {
+    td::SharedObjectPool<Node> pool;
+    pool.alloc();
+    pool.alloc();
+    pool.alloc();
+    pool.alloc();
+    pool.alloc();
+    CHECK(Node::cnt() == 0);
+    CHECK(pool.total_size() == 1);
+    CHECK(pool.calc_free_size() == 1);
+    pool.alloc(), pool.alloc(), pool.alloc();
+    CHECK(pool.total_size() == 3);
+    CHECK(pool.calc_free_size() == 3);
+  }
+  CHECK(Node::cnt() == 0);
+}
diff --git a/libs/tdlib/td/tdutils/test/crypto.cpp b/libs/tdlib/td/tdutils/test/crypto.cpp
new file mode 100644
index 0000000000..faf4ef61a4
--- /dev/null
+++ b/libs/tdlib/td/tdutils/test/crypto.cpp
@@ -0,0 +1,166 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/base64.h"
+#include "td/utils/common.h"
+#include "td/utils/crypto.h"
+#include "td/utils/Slice.h"
+#include "td/utils/tests.h"
+
+#include <limits>
+
+static td::vector<td::string> strings{"", "1", "short test string", td::string(1000000, 'a')};
+
+#if TD_HAVE_OPENSSL
+TEST(Crypto, AesCtrState) {
+  td::vector<td::uint32> answers1{0u,         1141589763u, 596296607u,  3673001485u, 2302125528u,
+                                  330967191u, 2047392231u, 3537459563u, 307747798u,  2149598133u};
+  td::vector<td::uint32> answers2{0u,         2053451992u, 1384063362u, 3266188502u, 2893295118u,
+                                  780356167u, 1904947434u, 2043402406u, 472080809u,  1807109488u};
+
+  std::size_t i = 0;
+  for (auto length : {0, 1, 31, 32, 33, 9999, 10000, 10001, 999999, 1000001}) {
+    td::uint32 seed = length;
+    td::string s(length, '\0');
+    for (auto &c : s) {
+      seed = seed * 123457567u + 987651241u;
+      c = static_cast<char>((seed >> 23) & 255);
+    }
+
+    td::UInt256 key;
+    for (auto &c : key.raw) {
+      seed = seed * 123457567u + 987651241u;
+      c = (seed >> 23) & 255;
+    }
+    td::UInt128 iv;
+    for (auto &c : iv.raw) {
+      seed = seed * 123457567u + 987651241u;
+      c = (seed >> 23) & 255;
+    }
+
+    td::AesCtrState state;
+    state.init(key, iv);
+    td::string t(length, '\0');
+    state.encrypt(s, t);
+    ASSERT_EQ(answers1[i], td::crc32(t));
+    state.init(key, iv);
+    state.decrypt(t, t);
+    ASSERT_STREQ(s, t);
+
+    for (auto &c : iv.raw) {
+      c = 0xFF;
+    }
+    state.init(key, iv);
+    state.encrypt(s, t);
+    ASSERT_EQ(answers2[i], td::crc32(t));
+
+    i++;
+  }
+}
+
+TEST(Crypto, Sha256State) {
+  for (auto length : {0, 1, 31, 32, 33, 9999, 10000, 10001, 999999, 1000001}) {
+    auto s = td::rand_string(std::numeric_limits<char>::min(), std::numeric_limits<char>::max(), length);
+    td::UInt256 baseline;
+    td::sha256(s, td::MutableSlice(baseline.raw, 32));
+
+    td::Sha256State state;
+    td::sha256_init(&state);
+    auto v = td::rand_split(s);
+    for (auto &x : v) {
+      td::sha256_update(x, &state);
+    }
+    td::UInt256 result;
+    td::sha256_final(&state, td::MutableSlice(result.raw, 32));
+    ASSERT_TRUE(baseline == result);
+  }
+}
+
+TEST(Crypto, PBKDF) {
+  td::vector<td::string> passwords{"", "qwerty", std::string(1000, 'a')};
+  td::vector<td::string> salts{"", "qwerty", std::string(1000, 'a')};
+  td::vector<int> iteration_counts{1, 2, 1000};
+  td::vector<td::Slice> answers{
+      "984LZT0tcqQQjPWr6RL/3Xd2Ftu7J6cOggTzri0Pb60=", "lzmEEdaupDp3rO+SImq4J41NsGaL0denanJfdoCsRcU=",
+      "T8WKIcEAzhg1uPmZHXOLVpZdFLJOF2H73/xprF4LZno=", "NHxAnMhPOATsb1wV0cGDlAIs+ofzI6I4I8eGJeWN9Qw=",
+      "fjYi7waEPjbVYEuZ61/Nm2hbk/vRdShoJoXg4Ygnqe4=", "GhW6e95hGJSf+ID5IrSbvzWyBZ1l35A+UoL55Uh/njk=",
+      "BueLDpqSCEc0GWk83WgMwz3UsWwfvVKcvllETSB/Yq8=", "hgHgJZNWRh78PyPdVJsK8whgHOHQbNQiyaTuGDX2IFo=",
+      "T2xdyNT1GlcA4+MVNzOe7NCgSAAzNkanNsmuoSr+4xQ=", "/f6t++GUPE+e63+0TrlInL+UsmzRSAAFopa8BBBmb2w=",
+      "8Zn98QEAKS9wPOUlN09+pfm0SWs1IGeQxQkNMT/1k48=", "sURLQ/6UX/KVYedyQB21oAtMJ+STZ4iwpxfQtqmWkLw=",
+      "T9t/EJXFpPs2Lhca7IVGphTC/OdEloPMHw1UhDnXcyQ=", "TIrtN05E9KQL6Lp/wjtbsFS+KkWZ8jlGK0ErtaoitOg=",
+      "+1KcMBjyUNz5VMaIfE5wkGwS6I+IQ5FhK+Ou2HgtVoQ=", "h36ci1T0vGllCl/xJxq6vI7n28Bg40dilzWOKg6Jt8k=",
+      "9uwsHJsotTiTqqCYftN729Dg7QI2BijIjV2MvSEUAeE=", "/l+vd/XYgbioh1SfLMaGRr13udmY6TLSlG4OYmytwGU=",
+      "7qfZZBbMRLtgjqq7GHgWa/UfXPajW8NXpJ6/T3P1rxI=", "ufwz94p28WnoOFdbrb1oyQEzm/v0CV2b0xBVxeEPJGA=",
+      "T/PUUBX2vGMUsI6httlhbMHlGPMvqFBNzayU5voVlaw=", "viMvsvTg9GfQymF3AXZ8uFYTDa3qLrqJJk9w/74iZfg=",
+      "HQF+rOZMW4DAdgZz8kAMe28eyIi0rs3a3u/mUeGPNfs=", "7lBVA+GnSxWF/eOo+tyyTB7niMDl1MqP8yzo+xnHTyw=",
+      "aTWb7HQAxaTKhSiRPY3GuM1GVmq/FPuwWBU/TUpdy70=", "fbg8M/+Ht/oU+UAZ4dQcGPo+wgCCHaA+GM4tm5jnWcY=",
+      "DJbCGFMIR/5neAlpda8Td5zftK4NGekVrg2xjrKW/4c="};
+
+  std::size_t pos = 0;
+  for (auto &password : passwords) {
+    for (auto &salt : salts) {
+      for (auto &iteration_count : iteration_counts) {
+        char result[32];
+        td::pbkdf2_sha256(password, salt, iteration_count, {result, 32});
+        ASSERT_STREQ(answers[pos], td::base64_encode({result, 32}));
+        pos++;
+      }
+    }
+  }
+}
+
+TEST(Crypto, sha1) {
+  td::vector<td::Slice> answers{"2jmj7l5rSw0yVb/vlWAYkK/YBwk=", "NWoZK3kTsExUV00Ywo1G5jlUKKs=",
+                                "uRysQwoax0pNJeBC3+zpQzJy1rA=", "NKqXPNTE2qT2Husr260nMWU0AW8="};
+
+  for (std::size_t i = 0; i < strings.size(); i++) {
+    unsigned char output[20];
+    td::sha1(strings[i], output);
+    ASSERT_STREQ(answers[i], td::base64_encode(td::Slice(output, 20)));
+  }
+}
+
+TEST(Crypto, sha256) {
+  td::vector<td::Slice> answers{
+      "47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=", "a4ayc/80/OGda4BO/1o/V0etpOqiLx1JwB5S3beHW0s=",
+      "yPMaY7Q8PKPwCsw64UnDD5mhRcituEJgzLZMvr0O8pY=", "zcduXJkU+5KBocfihNc+Z/GAmkiklyAOBG05zMcRLNA="};
+
+  for (std::size_t i = 0; i < strings.size(); i++) {
+    td::string output(32, '\0');
+    td::sha256(strings[i], output);
+    ASSERT_STREQ(answers[i], td::base64_encode(output));
+  }
+}
+
+TEST(Crypto, md5) {
+  td::vector<td::Slice> answers{
+      "1B2M2Y8AsgTpgAmY7PhCfg==", "xMpCOKC5I4INzFCab3WEmw==", "vwBninYbDRkgk+uA7GMiIQ==", "dwfWrk4CfHDuoqk1wilvIQ=="};
+
+  for (std::size_t i = 0; i < strings.size(); i++) {
+    td::string output(16, '\0');
+    td::md5(strings[i], output);
+    ASSERT_STREQ(answers[i], td::base64_encode(output));
+  }
+}
+#endif
+
+#if TD_HAVE_ZLIB
+TEST(Crypto, crc32) {
+  td::vector<td::uint32> answers{0u, 2212294583u, 3013144151u, 3693461436u};
+
+  for (std::size_t i = 0; i < strings.size(); i++) {
+    ASSERT_EQ(answers[i], td::crc32(strings[i]));
+  }
+}
+#endif
+
+TEST(Crypto, crc64) {
+  td::vector<td::uint64> answers{0ull, 3039664240384658157ull, 17549519902062861804ull, 8794730974279819706ull};
+
+  for (std::size_t i = 0; i < strings.size(); i++) {
+    ASSERT_EQ(answers[i], td::crc64(strings[i]));
+  }
+}
diff --git a/libs/tdlib/td/tdutils/test/filesystem.cpp b/libs/tdlib/td/tdutils/test/filesystem.cpp
new file mode 100644
index 0000000000..a0a92c14eb
--- /dev/null
+++ b/libs/tdlib/td/tdutils/test/filesystem.cpp
@@ -0,0 +1,41 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/filesystem.h"
+#include "td/utils/tests.h"
+
+TEST(Misc, clean_filename) {
+  using td::clean_filename;
+  ASSERT_STREQ(clean_filename("-1234567"), "-1234567");
+  ASSERT_STREQ(clean_filename(".git"), "git");
+  ASSERT_STREQ(clean_filename("../../.git"), "git");
+  ASSERT_STREQ(clean_filename(".././.."), "");
+  ASSERT_STREQ(clean_filename("../"), "");
+  ASSERT_STREQ(clean_filename(".."), "");
+  ASSERT_STREQ(clean_filename("test/git/   as   dsa  .   a"), "as   dsa.a");
+  ASSERT_STREQ(clean_filename("     .    "), "");
+  ASSERT_STREQ(clean_filename("!@#$%^&*()_+-=[]{;|:\"}'<>?,.`~"), "!@#$%^  ()_+-=[]{;   }    ,.~");
+  ASSERT_STREQ(clean_filename("!@#$%^&*()_+-=[]{}\\|:\";'<>?,.`~"), ";    ,.~");
+  ASSERT_STREQ(clean_filename("عرفها بعد قد. هذا مع تاريخ اليميني واندونيسيا،, لعدم تاريخ لهيمنة الى"),
+               "عرفها بعد قد.هذا مع تاريخ اليميني");
+  ASSERT_STREQ(
+      clean_filename(
+          "012345678901234567890123456789012345678901234567890123456789adsasdasdsaa.01234567890123456789asdasdasdasd"),
+      "012345678901234567890123456789012345678901234567890123456789.01234567890123456789");
+  ASSERT_STREQ(clean_filename("01234567890123456789012345678901234567890123456789<>*?: <>*?:0123456789adsasdasdsaa.   "
+                              "0123456789`<><<>><><>0123456789asdasdasdasd"),
+               "01234567890123456789012345678901234567890123456789.0123456789");
+  ASSERT_STREQ(clean_filename("01234567890123456789012345678901234567890123456789<>*?: <>*?:0123456789adsasdasdsaa.   "
+                              "0123456789`<><><>0123456789asdasdasdasd"),
+               "01234567890123456789012345678901234567890123456789.0123456789       012");
+  ASSERT_STREQ(clean_filename("C:/document.tar.gz"), "document.tar.gz");
+  ASSERT_STREQ(clean_filename("test...."), "test");
+  ASSERT_STREQ(clean_filename("....test"), "test");
+  ASSERT_STREQ(clean_filename("test.exe...."), "test.exe");  // extension has changed
+  ASSERT_STREQ(clean_filename("test.exe01234567890123456789...."),
+               "test.exe01234567890123456789");  // extension may be more then 20 characters
+  ASSERT_STREQ(clean_filename("....test....asdf"), "test.asdf");
+}
diff --git a/libs/tdlib/td/tdutils/test/gzip.cpp b/libs/tdlib/td/tdutils/test/gzip.cpp
new file mode 100644
index 0000000000..e4bd81eb0d
--- /dev/null
+++ b/libs/tdlib/td/tdutils/test/gzip.cpp
@@ -0,0 +1,113 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/buffer.h"
+#include "td/utils/ByteFlow.h"
+#include "td/utils/Gzip.h"
+#include "td/utils/GzipByteFlow.h"
+#include "td/utils/logging.h"
+#include "td/utils/Status.h"
+#include "td/utils/tests.h"
+
+static void encode_decode(td::string s) {
+  auto r = td::gzencode(s, 2);
+  ASSERT_TRUE(!r.empty());
+  if (r.empty()) {
+    return;
+  }
+  auto new_s = td::gzdecode(r.as_slice());
+  ASSERT_TRUE(!new_s.empty());
+  if (new_s.empty()) {
+    return;
+  }
+  ASSERT_EQ(s, new_s.as_slice().str());
+}
+
+TEST(Gzip, gzencode_gzdecode) {
+  auto str = td::rand_string(0, 127, 1000);
+  encode_decode(str);
+  str = td::rand_string('a', 'z', 1000000);
+  encode_decode(str);
+  str = td::string(1000000, 'a');
+  encode_decode(str);
+}
+
+TEST(Gzip, flow) {
+  auto str = td::rand_string('a', 'z', 1000000);
+  auto parts = td::rand_split(str);
+
+  auto input_writer = td::ChainBufferWriter::create_empty();
+  auto input = input_writer.extract_reader();
+  td::ByteFlowSource source(&input);
+  td::GzipByteFlow gzip_flow(td::Gzip::Encode);
+  gzip_flow = td::GzipByteFlow(td::Gzip::Encode);
+  td::ByteFlowSink sink;
+
+  source >> gzip_flow >> sink;
+
+  ASSERT_TRUE(!sink.is_ready());
+  for (auto &part : parts) {
+    input_writer.append(part);
+    source.wakeup();
+  }
+  ASSERT_TRUE(!sink.is_ready());
+  source.close_input(td::Status::OK());
+  ASSERT_TRUE(sink.is_ready());
+  ASSERT_TRUE(sink.status().is_ok());
+  auto res = sink.result()->move_as_buffer_slice().as_slice().str();
+  ASSERT_TRUE(!res.empty());
+  ASSERT_EQ(td::gzencode(str, 2).as_slice().str(), res);
+}
+TEST(Gzip, flow_error) {
+  auto str = td::rand_string('a', 'z', 1000000);
+  auto zip = td::gzencode(str).as_slice().str();
+  zip.resize(zip.size() - 1);
+  auto parts = td::rand_split(zip);
+
+  auto input_writer = td::ChainBufferWriter();
+  auto input = input_writer.extract_reader();
+  td::ByteFlowSource source(&input);
+  td::GzipByteFlow gzip_flow(td::Gzip::Decode);
+  td::ByteFlowSink sink;
+
+  source >> gzip_flow >> sink;
+
+  ASSERT_TRUE(!sink.is_ready());
+  for (auto &part : parts) {
+    input_writer.append(part);
+    source.wakeup();
+  }
+  ASSERT_TRUE(!sink.is_ready());
+  source.close_input(td::Status::OK());
+  ASSERT_TRUE(sink.is_ready());
+  ASSERT_TRUE(!sink.status().is_ok());
+}
+
+TEST(Gzip, encode_decode_flow) {
+  auto str = td::rand_string('a', 'z', 1000000);
+  auto parts = td::rand_split(str);
+  auto input_writer = td::ChainBufferWriter::create_empty();
+  auto input = input_writer.extract_reader();
+  td::ByteFlowSource source(&input);
+  td::GzipByteFlow gzip_encode_flow(td::Gzip::Encode);
+  td::GzipByteFlow gzip_decode_flow(td::Gzip::Decode);
+  td::GzipByteFlow gzip_encode_flow2(td::Gzip::Encode);
+  td::GzipByteFlow gzip_decode_flow2(td::Gzip::Decode);
+  td::ByteFlowSink sink;
+  source >> gzip_encode_flow >> gzip_decode_flow >> gzip_encode_flow2 >> gzip_decode_flow2 >> sink;
+
+  ASSERT_TRUE(!sink.is_ready());
+  for (auto &part : parts) {
+    input_writer.append(part);
+    source.wakeup();
+  }
+  ASSERT_TRUE(!sink.is_ready());
+  source.close_input(td::Status::OK());
+  ASSERT_TRUE(sink.is_ready());
+  LOG_IF(ERROR, sink.status().is_error()) << sink.status();
+  ASSERT_TRUE(sink.status().is_ok());
+  ASSERT_EQ(str, sink.result()->move_as_buffer_slice().as_slice().str());
+}
diff --git a/libs/tdlib/td/tdutils/test/heap.cpp b/libs/tdlib/td/tdutils/test/heap.cpp
new file mode 100644
index 0000000000..0dcfcf98ff
--- /dev/null
+++ b/libs/tdlib/td/tdutils/test/heap.cpp
@@ -0,0 +1,178 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/tests.h"
+
+#include "td/utils/common.h"
+#include "td/utils/Heap.h"
+#include "td/utils/logging.h"
+#include "td/utils/Random.h"
+
+#include <algorithm>
+#include <cstdio>
+#include <cstdlib>
+#include <set>
+#include <utility>
+
+REGISTER_TESTS(heap)
+
+using namespace td;
+
+TEST(Heap, sort_random_perm) {
+  int n = 1000000;
+  std::vector<int> v(n);
+  for (int i = 0; i < n; i++) {
+    v[i] = i;
+  }
+  std::srand(123);
+  std::random_shuffle(v.begin(), v.end());
+  std::vector<HeapNode> nodes(n);
+  KHeap<int> kheap;
+  for (int i = 0; i < n; i++) {
+    kheap.insert(v[i], &nodes[i]);
+  }
+  for (int i = 0; i < n; i++) {
+    ASSERT_EQ(i, kheap.top_key());
+    kheap.pop();
+  }
+};
+
+class CheckedHeap {
+ public:
+  void set_max_size(int max_size) {
+    nodes.resize(max_size);
+    free_ids.resize(max_size);
+    rev_ids.resize(max_size);
+    for (int i = 0; i < max_size; i++) {
+      free_ids[i] = max_size - i - 1;
+      nodes[i].value = i;
+    }
+  }
+  static void xx(int key, const HeapNode *heap_node) {
+    const Node *node = static_cast<const Node *>(heap_node);
+    std::fprintf(stderr, "(%d;%d)", node->key, node->value);
+  }
+  void check() const {
+    for (auto p : set_heap) {
+      std::fprintf(stderr, "(%d;%d)", p.first, p.second);
+    }
+    std::fprintf(stderr, "\n");
+    kheap.for_each(xx);
+    std::fprintf(stderr, "\n");
+    kheap.check();
+  }
+  int random_id() const {
+    CHECK(!empty());
+    return ids[Random::fast(0, static_cast<int>(ids.size() - 1))];
+  }
+  size_t size() const {
+    return ids.size();
+  }
+  bool empty() const {
+    return ids.empty();
+  }
+
+  int top_key() const {
+    CHECK(!empty());
+    int res = set_heap.begin()->first;
+    ASSERT_EQ(set_heap.size(), kheap.size());
+    ASSERT_EQ(res, kheap.top_key());
+    return res;
+  }
+  int insert(int key) {
+    // std::fprintf(stderr, "insert %d\n", key);
+    int id;
+    if (free_ids.empty()) {
+      UNREACHABLE();
+      id = static_cast<int>(nodes.size());
+      nodes.emplace_back(key, id);
+      rev_ids.push_back(-1);
+    } else {
+      id = free_ids.back();
+      free_ids.pop_back();
+      nodes[id].key = key;
+    }
+    rev_ids[id] = static_cast<int>(ids.size());
+    ids.push_back(id);
+    kheap.insert(key, &nodes[id]);
+    set_heap.emplace(key, id);
+    return id;
+  }
+  void fix_key(int new_key, int id) {
+    // std::fprintf(stderr, "fix key %d %d (old_key = %d)\n", new_key, id, nodes[id].key);
+    set_heap.erase(std::make_pair(nodes[id].key, id));
+    nodes[id].key = new_key;
+    kheap.fix(new_key, &nodes[id]);
+    set_heap.emplace(new_key, id);
+  }
+  void erase(int id) {
+    // std::fprintf(stderr, "erase %d\n", id);
+    int pos = rev_ids[id];
+    CHECK(pos != -1);
+    ids[pos] = ids.back();
+    rev_ids[ids[pos]] = pos;
+    ids.pop_back();
+    rev_ids[id] = -1;
+    free_ids.push_back(id);
+
+    kheap.erase(&nodes[id]);
+    set_heap.erase(std::make_pair(nodes[id].key, id));
+  }
+  void pop() {
+    // std::fprintf(stderr, "pop\n");
+    CHECK(!empty());
+    Node *node = static_cast<Node *>(kheap.pop());
+    int id = node->value;
+    ASSERT_EQ(node->key, set_heap.begin()->first);
+
+    int pos = rev_ids[id];
+    CHECK(pos != -1);
+    ids[pos] = ids.back();
+    rev_ids[ids[pos]] = pos;
+    ids.pop_back();
+    rev_ids[id] = -1;
+    free_ids.push_back(id);
+
+    set_heap.erase(std::make_pair(nodes[id].key, id));
+  }
+
+ private:
+  struct Node : public HeapNode {
+    Node() = default;
+    Node(int key, int value) : key(key), value(value) {
+    }
+    int key = 0;
+    int value = 0;
+  };
+  vector<int> ids;
+  vector<int> rev_ids;
+  vector<int> free_ids;
+  vector<Node> nodes;
+  std::set<std::pair<int, int>> set_heap;
+  KHeap<int> kheap;
+};
+
+TEST(Heap, random_events) {
+  CheckedHeap heap;
+  heap.set_max_size(1000);
+  for (int i = 0; i < 300000; i++) {
+    if (!heap.empty()) {
+      heap.top_key();
+    }
+
+    int x = Random::fast(0, 4);
+    if (heap.empty() || (x < 2 && heap.size() < 1000)) {
+      heap.insert(Random::fast(0, 99));
+    } else if (x < 3) {
+      heap.fix_key(Random::fast(0, 99), heap.random_id());
+    } else if (x < 4) {
+      heap.erase(heap.random_id());
+    } else if (x < 5) {
+      heap.pop();
+    }
+    // heap.check();
+  }
+}
diff --git a/libs/tdlib/td/tdutils/test/json.cpp b/libs/tdlib/td/tdutils/test/json.cpp
new file mode 100644
index 0000000000..deca81a791
--- /dev/null
+++ b/libs/tdlib/td/tdutils/test/json.cpp
@@ -0,0 +1,94 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/tests.h"
+
+#include "td/utils/JsonBuilder.h"
+#include "td/utils/logging.h"
+#include "td/utils/StringBuilder.h"
+
+#include <tuple>
+#include <utility>
+
+REGISTER_TESTS(json)
+
+using namespace td;
+
+static void decode_encode(string str, string result = "") {
+  auto str_copy = str;
+  auto r_value = json_decode(str_copy);
+  ASSERT_TRUE(r_value.is_ok());
+  if (r_value.is_error()) {
+    LOG(INFO) << r_value.error();
+    return;
+  }
+  auto new_str = json_encode<string>(r_value.ok());
+  if (result.empty()) {
+    result = str;
+  }
+  ASSERT_EQ(result, new_str);
+}
+
+TEST(JSON, array) {
+  char tmp[1000];
+  StringBuilder sb({tmp, sizeof(tmp)});
+  JsonBuilder jb(std::move(sb));
+  jb.enter_value().enter_array() << "Hello" << -123;
+  ASSERT_EQ(jb.string_builder().is_error(), false);
+  auto encoded = jb.string_builder().as_cslice().str();
+  ASSERT_EQ("[\"Hello\",-123]", encoded);
+  decode_encode(encoded);
+}
+TEST(JSON, object) {
+  char tmp[1000];
+  StringBuilder sb({tmp, sizeof(tmp)});
+  JsonBuilder jb(std::move(sb));
+  auto c = jb.enter_object();
+  c << std::tie("key", "value");
+  c << std::make_pair("1", 2);
+  c.leave();
+  ASSERT_EQ(jb.string_builder().is_error(), false);
+  auto encoded = jb.string_builder().as_cslice().str();
+  ASSERT_EQ("{\"key\":\"value\",\"1\":2}", encoded);
+  decode_encode(encoded);
+}
+
+TEST(JSON, nested) {
+  char tmp[1000];
+  StringBuilder sb({tmp, sizeof(tmp)});
+  JsonBuilder jb(std::move(sb));
+  {
+    auto a = jb.enter_array();
+    a << 1;
+    { a.enter_value().enter_array() << 2; }
+    a << 3;
+  }
+  ASSERT_EQ(jb.string_builder().is_error(), false);
+  auto encoded = jb.string_builder().as_cslice().str();
+  ASSERT_EQ("[1,[2],3]", encoded);
+  decode_encode(encoded);
+}
+
+TEST(JSON, kphp) {
+  decode_encode("[]");
+  decode_encode("[[]]");
+  decode_encode("{}");
+  decode_encode("{}");
+  decode_encode("\"\\n\"");
+  decode_encode(
+      "\""
+      "some long string \\t \\r \\\\ \\n \\f \\\" "
+      "\\u1234"
+      "\"");
+  decode_encode(
+      "{\"keyboard\":[[\"\\u2022 abcdefg\"],[\"\\u2022 hijklmnop\"],[\"\\u2022 "
+      "qrstuvwxyz\"]],\"one_time_keyboard\":true}");
+  decode_encode(
+      "  \n   {  \"keyboard\"  : \n  [[  \"\\u2022 abcdefg\"  ]  , \n [  \"\\u2022 hijklmnop\" \n ],[  \n \"\\u2022 "
+      "qrstuvwxyz\"]], \n  \"one_time_keyboard\"\n:\ntrue\n}\n   \n",
+      "{\"keyboard\":[[\"\\u2022 abcdefg\"],[\"\\u2022 hijklmnop\"],[\"\\u2022 "
+      "qrstuvwxyz\"]],\"one_time_keyboard\":true}");
+}
diff --git a/libs/tdlib/td/tdutils/test/misc.cpp b/libs/tdlib/td/tdutils/test/misc.cpp
new file mode 100644
index 0000000000..dd1f1ec457
--- /dev/null
+++ b/libs/tdlib/td/tdutils/test/misc.cpp
@@ -0,0 +1,262 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/base64.h"
+#include "td/utils/HttpUrl.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/EventFd.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/port/path.h"
+#include "td/utils/port/sleep.h"
+#include "td/utils/port/Stat.h"
+#include "td/utils/port/thread.h"
+#include "td/utils/Random.h"
+#include "td/utils/Slice.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tests.h"
+
+#include <atomic>
+#include <clocale>
+#include <limits>
+#include <locale>
+
+using namespace td;
+
+#if TD_LINUX || TD_DARWIN
+TEST(Misc, update_atime_saves_mtime) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR));
+  std::string name = "test_file";
+  unlink(name).ignore();
+  auto r_file = FileFd::open(name, FileFd::Read | FileFd::Flags::Create | FileFd::Flags::Truncate);
+  LOG_IF(ERROR, r_file.is_error()) << r_file.error();
+  ASSERT_TRUE(r_file.is_ok());
+  r_file.move_as_ok().close();
+
+  auto info = stat(name).ok();
+  int32 tests_ok = 0;
+  int32 tests_wa = 0;
+  for (int i = 0; i < 10000; i++) {
+    update_atime(name).ensure();
+    auto new_info = stat(name).ok();
+    if (info.mtime_nsec_ == new_info.mtime_nsec_) {
+      tests_ok++;
+    } else {
+      tests_wa++;
+      info.mtime_nsec_ = new_info.mtime_nsec_;
+    }
+    ASSERT_EQ(info.mtime_nsec_, new_info.mtime_nsec_);
+    usleep_for(Random::fast(0, 1000));
+  }
+  if (tests_wa > 0) {
+    LOG(ERROR) << "Access time was unexpectedly updated " << tests_wa << " times";
+  }
+  unlink(name).ensure();
+}
+
+TEST(Misc, update_atime_change_atime) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR));
+  std::string name = "test_file";
+  unlink(name).ignore();
+  auto r_file = FileFd::open(name, FileFd::Read | FileFd::Flags::Create | FileFd::Flags::Truncate);
+  LOG_IF(ERROR, r_file.is_error()) << r_file.error();
+  ASSERT_TRUE(r_file.is_ok());
+  r_file.move_as_ok().close();
+  auto info = stat(name).ok();
+  // not enough for fat and e.t.c.
+  usleep_for(5000000);
+  update_atime(name).ensure();
+  auto new_info = stat(name).ok();
+  if (info.atime_nsec_ == new_info.atime_nsec_) {
+    LOG(ERROR) << "Access time was unexpectedly not changed";
+  }
+  unlink(name).ensure();
+}
+#endif
+
+TEST(Misc, errno_tls_bug) {
+  // That's a problem that should be avoided
+  // errno = 0;
+  // impl_.alloc(123);
+  // CHECK(errno == 0);
+
+#if !TD_THREAD_UNSUPPORTED && !TD_EVENTFD_UNSUPPORTED
+  EventFd test_event_fd;
+  test_event_fd.init();
+  std::atomic<int> s(0);
+  s = 1;
+  td::thread th([&] {
+    while (s != 1) {
+    }
+    test_event_fd.acquire();
+  });
+  th.join();
+
+  for (int i = 0; i < 1000; i++) {
+    vector<EventFd> events(10);
+    vector<td::thread> threads;
+    for (auto &event : events) {
+      event.init();
+      event.release();
+    }
+    for (auto &event : events) {
+      threads.push_back(td::thread([&] {
+        {
+          EventFd tmp;
+          tmp.init();
+          tmp.acquire();
+        }
+        event.acquire();
+      }));
+    }
+    for (auto &thread : threads) {
+      thread.join();
+    }
+  }
+#endif
+}
+
+TEST(Misc, base64) {
+  ASSERT_TRUE(is_base64("dGVzdA==") == true);
+  ASSERT_TRUE(is_base64("dGVzdB==") == false);
+  ASSERT_TRUE(is_base64("dGVzdA=") == false);
+  ASSERT_TRUE(is_base64("dGVzdA") == false);
+  ASSERT_TRUE(is_base64("dGVz") == true);
+  ASSERT_TRUE(is_base64("") == true);
+  ASSERT_TRUE(is_base64("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/") == true);
+  ASSERT_TRUE(is_base64("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=") == false);
+  ASSERT_TRUE(is_base64("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-/") == false);
+  ASSERT_TRUE(is_base64("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_") == false);
+  ASSERT_TRUE(is_base64("====") == false);
+
+  ASSERT_TRUE(is_base64url("dGVzdA==") == true);
+  ASSERT_TRUE(is_base64url("dGVzdB==") == false);
+  ASSERT_TRUE(is_base64url("dGVzdA=") == false);
+  ASSERT_TRUE(is_base64url("dGVzdA") == true);
+  ASSERT_TRUE(is_base64url("dGVz") == true);
+  ASSERT_TRUE(is_base64url("") == true);
+  ASSERT_TRUE(is_base64url("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_") == true);
+  ASSERT_TRUE(is_base64url("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_=") == false);
+  ASSERT_TRUE(is_base64url("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-/") == false);
+  ASSERT_TRUE(is_base64url("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/") == false);
+  ASSERT_TRUE(is_base64url("====") == false);
+
+  for (int l = 0; l < 300000; l += l / 20 + l / 1000 * 500 + 1) {
+    for (int t = 0; t < 10; t++) {
+      string s = rand_string(std::numeric_limits<char>::min(), std::numeric_limits<char>::max(), l);
+      string encoded = base64url_encode(s);
+      auto decoded = base64url_decode(encoded);
+      ASSERT_TRUE(decoded.is_ok());
+      ASSERT_TRUE(decoded.ok() == s);
+
+      encoded = base64_encode(s);
+      decoded = base64_decode(encoded);
+      ASSERT_TRUE(decoded.is_ok());
+      ASSERT_TRUE(decoded.ok() == s);
+    }
+  }
+
+  ASSERT_TRUE(base64url_decode("dGVzdA").is_ok());
+  ASSERT_TRUE(base64url_decode("dGVzdB").is_error());
+  ASSERT_TRUE(base64_encode(base64url_decode("dGVzdA").ok()) == "dGVzdA==");
+  ASSERT_TRUE(base64_encode("any carnal pleas") == "YW55IGNhcm5hbCBwbGVhcw==");
+  ASSERT_TRUE(base64_encode("any carnal pleasu") == "YW55IGNhcm5hbCBwbGVhc3U=");
+  ASSERT_TRUE(base64_encode("any carnal pleasur") == "YW55IGNhcm5hbCBwbGVhc3Vy");
+  ASSERT_TRUE(base64_encode("      /'.;.';≤.];,].',[.;/,.;/]/..;!@#!*(%?::;!%\";") ==
+              "ICAgICAgLycuOy4nO+KJpC5dOyxdLicsWy47LywuOy9dLy4uOyFAIyEqKCU/"
+              "Ojo7ISUiOw==");
+}
+
+TEST(Misc, to_integer) {
+  ASSERT_EQ(to_integer<int32>("-1234567"), -1234567);
+  ASSERT_EQ(to_integer<int64>("-1234567"), -1234567);
+  ASSERT_EQ(to_integer<uint32>("-1234567"), 0u);
+  ASSERT_EQ(to_integer<int16>("-1234567"), 10617);
+  ASSERT_EQ(to_integer<uint16>("-1234567"), 0u);
+  ASSERT_EQ(to_integer<int16>("-1254567"), -9383);
+  ASSERT_EQ(to_integer<uint16>("1254567"), 9383u);
+  ASSERT_EQ(to_integer<int64>("-12345678910111213"), -12345678910111213);
+  ASSERT_EQ(to_integer<uint64>("12345678910111213"), 12345678910111213ull);
+
+  ASSERT_EQ(to_integer_safe<int32>("-1234567").ok(), -1234567);
+  ASSERT_EQ(to_integer_safe<int64>("-1234567").ok(), -1234567);
+  ASSERT_TRUE(to_integer_safe<uint32>("-1234567").is_error());
+  ASSERT_TRUE(to_integer_safe<int16>("-1234567").is_error());
+  ASSERT_TRUE(to_integer_safe<uint16>("-1234567").is_error());
+  ASSERT_TRUE(to_integer_safe<int16>("-1254567").is_error());
+  ASSERT_TRUE(to_integer_safe<uint16>("1254567").is_error());
+  ASSERT_EQ(to_integer_safe<int64>("-12345678910111213").ok(), -12345678910111213);
+  ASSERT_EQ(to_integer_safe<uint64>("12345678910111213").ok(), 12345678910111213ull);
+  ASSERT_TRUE(to_integer_safe<uint64>("-12345678910111213").is_error());
+}
+
+static void test_to_double_one(CSlice str, Slice expected, int precision = 6) {
+  auto result = PSTRING() << td::StringBuilder::FixedDouble(to_double(str), precision);
+  if (expected != result) {
+    LOG(ERROR) << "To double conversion failed: have " << str << ", expected " << expected << ", parsed "
+               << to_double(str) << ", got " << result;
+  }
+}
+
+static void test_to_double() {
+  test_to_double_one("0", "0.000000");
+  test_to_double_one("1", "1.000000");
+  test_to_double_one("-10", "-10.000000");
+  test_to_double_one("1.234", "1.234000");
+  test_to_double_one("-1.234e2", "-123.400000");
+  test_to_double_one("inf", "inf");
+  test_to_double_one("  inF  asdasd", "inf");
+  test_to_double_one("  inFasdasd", "0.000000");
+  test_to_double_one("  NaN", "nan");
+  test_to_double_one("  12345678910111213141516171819  asdasd", "12345678910111213670658736128.000000");
+  test_to_double_one("1.234567891011121314E123",
+                     "1234567891011121363209105003376291141757777526749278953577304234065881343284952489418916814035346"
+                     "625663604561924259911303168.000000");
+  test_to_double_one("1.234567891011121314E-9", "0.000000");
+  test_to_double_one("123456789", "123456789.000000");
+  test_to_double_one("-1,234567891011121314E123", "-1.000000");
+  test_to_double_one("123456789", "123456789", 0);
+  test_to_double_one("1.23456789", "1", 0);
+  test_to_double_one("1.23456789", "1.2", 1);
+  test_to_double_one("1.23456789", "1.23", 2);
+  test_to_double_one("1.23456789", "1.235", 3);
+  test_to_double_one("1.23456789", "1.2346", 4);
+  test_to_double_one("1.23456789", "1.23457", 5);
+  test_to_double_one("1.23456789", "1.234568", 6);
+  test_to_double_one("1.23456789", "1.2345679", 7);
+  test_to_double_one("1.23456789", "1.23456789", 8);
+  test_to_double_one("1.23456789", "1.234567890", 9);
+  test_to_double_one("1.23456789", "1.2345678900", 10);
+}
+
+TEST(Misc, to_double) {
+  test_to_double();
+  const char *locale_name = (std::setlocale(LC_ALL, "fr-FR") == nullptr ? "" : "fr-FR");
+  std::locale new_locale(locale_name);
+  std::locale::global(new_locale);
+  test_to_double();
+  std::locale::global(std::locale::classic());
+  test_to_double();
+}
+
+static void test_get_url_query_file_name_one(const char *prefix, const char *suffix, const char *file_name) {
+  auto path = string(prefix) + string(file_name) + string(suffix);
+  ASSERT_STREQ(file_name, get_url_query_file_name(path));
+  ASSERT_STREQ(file_name, get_url_file_name("http://telegram.org" + path));
+  ASSERT_STREQ(file_name, get_url_file_name("http://telegram.org:80" + path));
+  ASSERT_STREQ(file_name, get_url_file_name("telegram.org" + path));
+}
+
+TEST(Misc, get_url_query_file_name) {
+  for (auto suffix : {"?t=1#test", "#test?t=1", "#?t=1", "?t=1#", "#test", "?t=1", "#", "?", ""}) {
+    test_get_url_query_file_name_one("", suffix, "");
+    test_get_url_query_file_name_one("/", suffix, "");
+    test_get_url_query_file_name_one("/a/adasd/", suffix, "");
+    test_get_url_query_file_name_one("/a/lklrjetn/", suffix, "adasd.asdas");
+    test_get_url_query_file_name_one("/", suffix, "a123asadas");
+    test_get_url_query_file_name_one("/", suffix, "\\a\\1\\2\\3\\a\\s\\a\\das");
+  }
+}
diff --git a/libs/tdlib/td/tdutils/test/pq.cpp b/libs/tdlib/td/tdutils/test/pq.cpp
new file mode 100644
index 0000000000..5210cc2638
--- /dev/null
+++ b/libs/tdlib/td/tdutils/test/pq.cpp
@@ -0,0 +1,118 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/tests.h"
+
+#include "td/utils/BigNum.h"
+#include "td/utils/common.h"
+#include "td/utils/crypto.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+
+#include <algorithm>
+#include <limits>
+#include <utility>
+
+REGISTER_TESTS(pq)
+
+using namespace td;
+
+#if TD_HAVE_OPENSSL
+static bool is_prime(uint64 x) {
+  for (uint64 d = 2; d < x && d * d <= x; d++) {
+    if (x % d == 0) {
+      return false;
+    }
+  }
+  return true;
+}
+
+static std::vector<uint64> gen_primes(uint64 L, uint64 R, int limit = 0) {
+  std::vector<uint64> res;
+  for (auto x = L; x <= R && (limit <= 0 || res.size() < static_cast<std::size_t>(limit)); x++) {
+    if (is_prime(x)) {
+      res.push_back(x);
+    }
+  }
+  return res;
+}
+
+static std::vector<uint64> gen_primes() {
+  std::vector<uint64> result;
+  append(result, gen_primes(1, 100));
+  append(result, gen_primes((1ull << 31) - 500000, std::numeric_limits<uint64>::max(), 5));
+  append(result, gen_primes((1ull << 32) - 500000, std::numeric_limits<uint64>::max(), 5));
+  append(result, gen_primes((1ull << 39) - 500000, std::numeric_limits<uint64>::max(), 1));
+  return result;
+}
+
+using PqQuery = std::pair<uint64, uint64>;
+static bool cmp(const PqQuery &a, const PqQuery &b) {
+  return a.first * a.second < b.first * b.second;
+}
+static std::vector<PqQuery> gen_pq_queries() {
+  std::vector<PqQuery> res;
+  auto primes = gen_primes();
+  for (auto q : primes) {
+    for (auto p : primes) {
+      if (p > q) {
+        break;
+      }
+      res.emplace_back(p, q);
+    }
+  }
+  std::sort(res.begin(), res.end(), cmp);
+  return res;
+}
+
+static void test_pq(uint64 first, uint64 second) {
+  BigNum p = BigNum::from_decimal(PSLICE() << first);
+  BigNum q = BigNum::from_decimal(PSLICE() << second);
+
+  BigNum pq;
+  BigNumContext context;
+  BigNum::mul(pq, p, q, context);
+  std::string pq_str = pq.to_binary();
+
+  std::string p_str, q_str;
+  int err = td::pq_factorize(pq_str, &p_str, &q_str);
+  CHECK(err == 0) << first << " * " << second;
+
+  BigNum p_res = BigNum::from_binary(p_str);
+  BigNum q_res = BigNum::from_binary(q_str);
+
+  CHECK(p_str == p.to_binary()) << td::tag("got", p_res.to_decimal()) << td::tag("expected", first);
+  CHECK(q_str == q.to_binary()) << td::tag("got", q_res.to_decimal()) << td::tag("expected", second);
+}
+#endif
+
+TEST(CryptoPQ, hands) {
+  ASSERT_EQ(1ull, td::pq_factorize(0));
+  ASSERT_EQ(1ull, td::pq_factorize(1));
+  ASSERT_EQ(1ull, td::pq_factorize(2));
+  ASSERT_EQ(1ull, td::pq_factorize(3));
+  ASSERT_EQ(2ull, td::pq_factorize(4));
+  ASSERT_EQ(1ull, td::pq_factorize(5));
+  ASSERT_EQ(3ull, td::pq_factorize(7 * 3));
+  ASSERT_EQ(179424611ull, td::pq_factorize(179424611ull * 179424673ull));
+
+#if TD_HAVE_OPENSSL
+  test_pq(4294467311, 4294467449);
+#endif
+}
+
+#if TD_HAVE_OPENSSL
+TEST(CryptoPQ, generated_slow) {
+  for (int i = 0; i < 100000; i++) {
+    test_pq(2, 2);
+  }
+  auto queries = gen_pq_queries();
+  for (auto query : queries) {
+    test_pq(query.first, query.second);
+  }
+}
+#endif
\ No newline at end of file
diff --git a/libs/tdlib/td/tdutils/test/variant.cpp b/libs/tdlib/td/tdutils/test/variant.cpp
new file mode 100644
index 0000000000..5c5e18d1d8
--- /dev/null
+++ b/libs/tdlib/td/tdutils/test/variant.cpp
@@ -0,0 +1,75 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/Slice.h"
+#include "td/utils/StringBuilder.h"
+#include "td/utils/tests.h"
+#include "td/utils/Variant.h"
+
+REGISTER_TESTS(variant);
+
+using namespace td;
+
+static const size_t BUF_SIZE = 1024 * 1024;
+static char buf[BUF_SIZE], buf2[BUF_SIZE];
+static StringBuilder sb(MutableSlice(buf, BUF_SIZE - 1));
+static StringBuilder sb2(MutableSlice(buf2, BUF_SIZE - 1));
+
+static std::string move_sb() {
+  auto res = sb.as_cslice().str();
+  sb.clear();
+  return res;
+}
+
+static std::string name(int id) {
+  if (id == 1) {
+    return "A";
+  }
+  if (id == 2) {
+    return "B";
+  }
+  if (id == 3) {
+    return "C";
+  }
+  return "";
+}
+
+template <int id>
+class Class {
+ public:
+  Class() {
+    sb << "+" << name(id);
+  }
+  Class(const Class &) = delete;
+  Class &operator=(const Class &) = delete;
+  Class(Class &&) = delete;
+  Class &operator=(Class &&) = delete;
+  ~Class() {
+    sb << "-" << name(id);
+  }
+};
+
+using A = Class<1>;
+using B = Class<2>;
+using C = Class<3>;
+
+TEST(Variant, simple) {
+  {
+    Variant<std::unique_ptr<A>, std::unique_ptr<B>, std::unique_ptr<C>> abc;
+    ASSERT_STREQ("", sb.as_cslice());
+    abc = std::make_unique<A>();
+    ASSERT_STREQ("+A", sb.as_cslice());
+    sb.clear();
+    abc = std::make_unique<B>();
+    ASSERT_STREQ("+B-A", sb.as_cslice());
+    sb.clear();
+    abc = std::make_unique<C>();
+    ASSERT_STREQ("+C-B", sb.as_cslice());
+    sb.clear();
+  }
+  ASSERT_STREQ("-C", move_sb());
+  sb.clear();
+};
diff --git a/libs/tdlib/td/test/CMakeLists.txt b/libs/tdlib/td/test/CMakeLists.txt
new file mode 100644
index 0000000000..d120d8d3fb
--- /dev/null
+++ b/libs/tdlib/td/test/CMakeLists.txt
@@ -0,0 +1,50 @@
+cmake_minimum_required(VERSION 3.0.2 FATAL_ERROR)
+
+#SOURCE SETS
+set(TD_TEST_SOURCE
+  ${CMAKE_CURRENT_SOURCE_DIR}/db.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/http.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/mtproto.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/message_entities.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/secret.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/string_cleaning.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/TestsRunner.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/tests_runner.cpp
+
+  ${CMAKE_CURRENT_SOURCE_DIR}/TestsRunner.h
+  ${CMAKE_CURRENT_SOURCE_DIR}/tests_runner.h
+
+  ${CMAKE_CURRENT_SOURCE_DIR}/data.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/data.h
+
+  ${TDUTILS_TEST_SOURCE}
+  ${TDACTOR_TEST_SOURCE}
+)
+set(TD_TEST_SOURCE ${TD_TEST_SOURCE} PARENT_SCOPE)
+
+set(TESTS_MAIN
+  main.cpp
+)
+
+add_library(all_tests STATIC ${TD_TEST_SOURCE})
+target_include_directories(all_tests PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>)
+target_link_libraries(all_tests PRIVATE tdactor tddb tdcore tdnet tdutils)
+
+if (NOT CMAKE_CROSSCOMPILING OR EMSCRIPTEN)
+  #Tests
+  add_executable(run_all_tests ${TESTS_MAIN} ${TD_TEST_SOURCE})
+  if (CLANG AND NOT CYGWIN AND NOT EMSCRIPTEN)
+    target_compile_options(run_all_tests PUBLIC -fsanitize=undefined -fno-sanitize=vptr)
+    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -fsanitize=undefined -fno-sanitize=vptr")
+  endif()
+  target_include_directories(run_all_tests PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>)
+  target_link_libraries(run_all_tests PRIVATE tdactor tddb tdcore tdnet tdutils)
+
+  if (CLANG)
+#    add_executable(fuzz_url fuzz_url.cpp)
+#    target_link_libraries(fuzz_url PRIVATE tdclient)
+#    target_compile_options(fuzz_url PRIVATE "-fsanitize-coverage=trace-pc-guard")
+  endif()
+
+  add_test(run_all_tests run_all_tests)
+endif()
diff --git a/libs/tdlib/td/test/TestsRunner.cpp b/libs/tdlib/td/test/TestsRunner.cpp
new file mode 100644
index 0000000000..fbe155738e
--- /dev/null
+++ b/libs/tdlib/td/test/TestsRunner.cpp
@@ -0,0 +1,63 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "test/TestsRunner.h"
+
+#include "td/utils/common.h"
+#include "td/utils/FileLog.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/path.h"
+#include "td/utils/tests.h"
+
+#include <limits>
+
+DESC_TESTS(string_cleaning);
+DESC_TESTS(message_entities);
+DESC_TESTS(variant);
+DESC_TESTS(secret);
+DESC_TESTS(actors_main);
+DESC_TESTS(actors_simple);
+DESC_TESTS(actors_workers);
+DESC_TESTS(db);
+DESC_TESTS(json);
+DESC_TESTS(http);
+DESC_TESTS(heap);
+DESC_TESTS(pq);
+DESC_TESTS(mtproto);
+
+namespace td {
+
+void TestsRunner::run_all_tests() {
+  LOAD_TESTS(string_cleaning);
+  LOAD_TESTS(message_entities);
+  LOAD_TESTS(variant);
+  LOAD_TESTS(secret);
+  LOAD_TESTS(actors_main);
+  LOAD_TESTS(actors_simple);
+  LOAD_TESTS(actors_workers);
+  LOAD_TESTS(db);
+  LOAD_TESTS(json);
+  LOAD_TESTS(http);
+  LOAD_TESTS(heap);
+  LOAD_TESTS(pq);
+  LOAD_TESTS(mtproto);
+  Test::run_all();
+}
+
+static FileLog file_log;
+static TsLog ts_log(&file_log);
+
+void TestsRunner::init(string dir) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(WARNING));
+  chdir(dir).ensure();
+  LOG(WARNING) << "Redirect log into " << tag("file", dir + TD_DIR_SLASH + "log.txt");
+  if (file_log.init("log.txt", std::numeric_limits<int64>::max())) {
+    log_interface = &ts_log;
+  }
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/test/TestsRunner.h b/libs/tdlib/td/test/TestsRunner.h
new file mode 100644
index 0000000000..a5bc66d855
--- /dev/null
+++ b/libs/tdlib/td/test/TestsRunner.h
@@ -0,0 +1,19 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+namespace td {
+
+class TestsRunner {
+ public:
+  static void init(string dir);
+  static void run_all_tests();
+};
+
+}  // namespace td
diff --git a/libs/tdlib/td/test/data.cpp b/libs/tdlib/td/test/data.cpp
new file mode 100644
index 0000000000..a57a9147c5
--- /dev/null
+++ b/libs/tdlib/td/test/data.cpp
@@ -0,0 +1,69 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "test/data.h"
+namespace td {
+static const char thumbnail_arr[] =
+    "_9j_4AAQSkZJRgABAQEASABIAAD_2wBDAAICAgICAQICAgIDAgIDAwYEAwMDAwcFBQQGCAcJCAgHCAgJCg0LCQoMCggICw8LDA0ODg8OCQsQERAOEQ"
+    "0ODg7_2wBDAQIDAwMDAwcEBAcOCQgJDg4ODg4ODg4ODg4ODg4ODg4ODg4ODg4ODg4ODg4ODg4ODg4ODg4ODg4ODg4ODg4ODg7_wAARCAAyADIDASIA"
+    "AhEBAxEB_8QAHAAAAQUBAQEAAAAAAAAAAAAAAAUGBwgJAgQD_8QAMRAAAgEDAwMDAgUDBQAAAAAAAQIDBAURAAYSByExCBNBFCIVMlFhcZGhsQkjUm"
+    "KB_8QAGgEAAgMBAQAAAAAAAAAAAAAABgcAAggEBf_EACgRAAECBgIBBAMBAQAAAAAAAAECEQADBAUhMRJBBhMyUWEUIlJCkf_aAAwDAQACEQMRAD8A"
+    "381CvUXrbtzYtTLa6ZPx3cKj76SGQLHTn491-_E_9QC38a464dSH2H08gpLZMI9x3dmhom7EwKB98uP2yAP3Ofg6z2M8jVXvM5qqkyFpeTsCCR3Lk9"
+    "y2eWe_yD3znTG8esEqtR-TVAlJ9qRgqbZJ6T1956ELjyG_T6RRpqQhJHvWrIS-gkf6UfjrGHMTVePUH1HuVYxp7rTWOFj9sVDRocfoOUgYk_00nUXX"
+    "XqdQTrIdzmsQgHhWUcLowOcdwoPwfB1W3fG8KjaNlpnoqNK-veCWVYXk9qL26eMSOXkPZclUUdxkk-QMaiPZPqFp9wdT7btC92iltlRcZvpqea33Na"
+    "mNZSuVjcY7BsYDA-SMjByD5c2w01V-DMp5aS4HtffypjnXffULxNPeqmjNwlVU1YZRcFtfCSRjfXRIfUa1bG9SFuuddDbt6UUdkqHIVbhTkmmJPjmp"
+    "-6P-ckfrjVno5ElgSWJ1kjdQyspyGB8EH51kUWDShpFIbAAkQEjsDktk5wAMAD9hq2Pp16lTrdl2BeJzJSyKzWWWRs8Co5NCD8qR3A-CCv6aE7_45T"
+    "y5SqijSUKTlSNhvlJ-tkPrI0YMLD5DUmYiTVrE2WssmYMEK_lYxvQLbYHYi4-jRo0p4bUZ6-oC7y3P1IXajJ5QW-lio4jyIKgqsreDg_cwPceQMY86"
+    "hQAKoUeAMdzk6lzrhb5aT1R7kUqSKpoaiLt-YNEo_wAqw_8ANMuqsVbTWy3x1tEbeXV2E0isWkOcn7QPABAyTnPxp9zfJPH_ABO1US6xYSJwSMZIHE"
+    "krIyriFYJA2obyIzbMst_8oulZLpwVeiVkA4BPIAIBwORTkAnQOsExZNddoWn1T9Kju6G1yU9bLW01ILraKetiqKgLDJHSH3gVi94hoxIBkOYwCM6r"
+    "x6yLDYdt9fOi9T03l3DfN2_h8VRPBdYF-uWp-pWSCmZY40CyZYqYuPJOSqQp-0TtuK1dPt0b6oLNvfZg3R9HDM8UU8X3orcQxTDqAGwnEk4J8kAEa8"
+    "th2NtTZnVjprfZ62fd9vgsMU9jmu1OZJ7YaZ-ApqFsKEVXYq0vEBnZeJIw5UdRfrd5Fd6mptyipCVMFMwUyQXDsWwWcAk6Goc1ts9dZLNT01enishy"
+    "PcQ6jgs40csSAHc4MPynrYKyxwXHgaenngWfhMvExBl5cWB8Fc4IPgg6WbJdqi07ntd5pJ-Ro6mGpgfOSntsGwD-hGRj9zpSHTjfm-t6XWt2zXWqhg"
+    "J-rqqGpo-VNLKMMY4nVwW5sCzKue5YjAPHTbobXf6eWjs9-t0duv1RHFIaSGpWYAT_AJMEAEEkkFWAYEeMYJd9vvtHeJyKWanPByT_AEBkD6ZzCUuX"
+    "j1fYKeZVypmCviAM_ofaTjB5MPrbuRGucUizU0c0bZR1DL2-CMjRriliFNbKanzn2olTP8DGjWczvGo0onQfcV666bXhFwsXUGKnhq6m0LItRSTSGN"
+    "KpUR5olZgDxAdCCcHCuT8Y1nd0O3dW9X-gta1nv0fTvct_u9xZZ4LuK-sjZgrSSokhb2hyBVEAwBGDjuQdft02GPcuxLjZ3dYnniIhlePmI5B-Vivy"
+    "AfIyMjI-dUZpukO99qbiEtv6YxVFQjk-9QVkP08mD5BGJMHzhhkds_roG8lNVUKlOhSwkJCSHPEJUVMwBcEqJDgx7NqlU9P6hQySslSgeyQA-W6SIb"
+    "O6tqQbUk2jcEu0k93WrRPrGjVZPd4_mRhjv7gRyvEqCMnHjTT6f1VmrfUttCyb2RL7FT0sFos9NV0iJTQUsCPUksVHeV5QWLcTyZBnHwp9RoKy47tp"
+    "pr5a7haK6mOGiniaBBjHZc_GRnlnP9iI1u1huF9r7dV2GrnpNx0NSs9BUUqM5Dg5AKr3Iz_Tv8Egnvg_h12Rbq2pXI9JC-BlBRZSikK5nJ_UEEAOzk"
+    "dCF_5N5hbJVzpKZM4rKeYmcQ6U8m4aDqKSC_F2B7OIsX1grfTIfVHsSh6gRXPZW5LeJLlYLxaqeWgt0pMyoyTVKf7QkZ4lAVuLEHAbDYMc7F3jsHdX"
+    "-tXPtXb9FX38PRrW1N5p0MlKwp6f3qcyOo4BFaQxA5yWVVxjSjvDp31r6rdNVgvHS2WgqaWZaumd6yn9mr44WSLizLKnuAI6lk7PChPbOrhem3phH0"
+    "k9Ie1NpyWZbHdVgM9ypRULMY5nYkoZFGG4jio8-PJ8nsE2bSLJQeK8j_oIPz0SNwRLpqKsokKUrk5H6l2YEKSrQ7AwexE76NGjXmx0QaMDRo1IkfKS"
+    "KKZCk0ayp_xdQR_fXEVLS0yn6emip8-fbjC_40aNWc66ijDbZj0YGjRo1WLwaNGjUiR__9k";
+
+const char *thumbnail = thumbnail_arr;
+const size_t thumbnail_size = sizeof(thumbnail_arr) - 1;
+
+static const char gzip_bomb_arr[] =
+    "eJzt3VlQU2cYxvGTSFSkqHWJuIHTUqotAetIBmWzVUeUqlRrFcIqZlxCUKRshZBULVS0oqLiwqJWUVwAQQNBgSgt1EHFlS1AQCsZ1qAsASKTRonnnJ"
+    "ledHrViz5cfvMOOd_v_d-eJCK5vf6MaUmDLK7Jk_tZ9sSDEyYmdo7fOMeqdKSs-jXRxA_m8_fZPGTMW-Rhlf-AP7XxrGTW-qCOyWPtB90qdo-"
+    "NHtXfEi3Wlul0bWrxYNa1QaVY12ure9OdRgz_SVzyX-"
+    "nS59eYP1uYV68zHBLi7xcf2qyd7ddSbhX2geFsfPs3aeO04xhKLWffzBGGQyOHIeckkUmXZ1qZoH2a4XBWddSKRKGJ-"
+    "9UQxe8HGIbDXaZLU4U8SfDf_-UhiXroGG0wJSatvIgVcbXihV2YKTnpdP6ulHWxUtaxsez9U96O_ahCypHn9_AnOow0nI3uu1gRN-"
+    "Qq18SU0wZXFVfwlcxblapX025Sk6mPNymY37bVhV0LeK_hp7-3gu3nNZizl7pj1FNVSYxlY1QxnzZ4QanK2c7waeuO-"
+    "MWbmly9NUfIuBQadLP6C8PZouwzf-QKTebaiGp-o-7o1Nrt7zKhq1CZQxt8og6pySOyeiNvlWaSk4UX5tdICf12vNvNSF_"
+    "3P2ukLLOkokDaHc17B7ItjPsbtnvQBls0snaepGrQ0SegipxsWHsykCfZlqKwoTYROPt1oIK5382XS7tjwmB0dYJRtDrPmrayHq1XH0cuEJlnXROQk"
+    "-o5K6WcRTceCKdQm-BOipQKGaXnbU_R7rhM5Ny-"
+    "jFmk4bGpwbBBkY2W3XjDOaGq2o6c1ByxUrBPe6qktNqmxzsqpMSLx0kraXf81dmi72NkOTyILJElskSWBLJElgSyRJbDg8gSWSJLZEkgS2RJIEtkOT"
+    "yILJElskSWBLJElgSyRJbDi0CWyBJZIktkiSyH74gskSWyRJYEskSWBLJElu_uiCyRJbJElgSyRJbDvsgSWSJLZIkskeXwJLJElsgSWSJLZPluEFn-"
+    "11nq_NUHhOP3MGfHl7pe3eBeYz_S1Jhbye4pZRxnTCxxbZeP9Jw3gnXUOLb4jm1MyAOjcEmSo-ESnr5HI-2Nj9_kupErWfL5sYyx-"
+    "phmrlrZSlZXqylU6gsrH5TVryVZHqWWLdY_hU9x2cDJhe8f7efK9XzzVczmzPtrqMF4_qUS_"
+    "ebj1iYWkHN9InW4gt2YExOkeUru6brq1UH951Spg4vSyY2e7V13Ii5RIhPk0gY3nmjNZplVNT09R-7zrEiprZey8q-kKZxCSdSOSMdN-s_"
+    "pjUrOyiD5t4jWNTdZ-nXWWlODVzekLwxklIba22WQ-FuUmpg8IcOmTRW2mhKKMh-"
+    "nbyRiyFwlaCV7ACUoQQlKUIISlKAEJShBCUpQghKUoAQlKEEJSlCCEpSgBCUoQQlKUIISlKAEJShBCUpQghKUoAQlKEEJSlCCEpSgBCUoQQlKUIISl"
+    "KAEJShBCcp_ouzPDS_"
+    "jjv6KMWnp4tNs6yuBM3bHLpkuGBP1nLgnMfa3DN8xwjrl9p14o26PpinFCzbvcpC7meuhEyLZUuJCaJGU9nmanev3cOQBLQeSaHfIyLjcYdno0LOUW"
+    "khtk2bB9revxtcp15Cvxj9qCEj9iSPfmpIlpE0W1k32N-naUPDiE-oOwm2t2xyM-8eKDlELCesXPVC8_XoFTd5T8usVrmuOb_"
+    "Y32eGpEpyiTdqGL61mOh7rjFhO5XDqZEHtKmbRYt9z1EJmxqR1S99-F8IQJ5T8LoQOp2aPamZy5UAtbXX15d4fSomE8w4-"
+    "tBzS0zOliRL1wyk0oDil6pa-"
+    "pbYQsZs31SwoQQlKUIISlKAEJShBCUpQghKUoAQlKEEJSlCCEpSgBCUoQQlKUIISlKAEJShBCUpQghKUoAQlKEEJSlCCEpSgBCUoQQlKUIISlKAEJS"
+    "hBCUpQ_jtKiTgqPPDO3MOL_Pv3TxL68UbFJ5tlxpXs_XLFDAd3Gy-JIPvL_"
+    "KOXG414uxZmy1zt7B9axXrM53w9d0a0L0vMGGduuE7ODydO5bOO39kQKiPf5d-Udqb6Ck8SEOGbKSMXsSmvXuqVR1T4ireEkA9010f1xDnVKNpCMy_"
+    "8PeXBKz7NVkGM9LnfeXeS7_LXbJ7NbWM3mjUkCTrJRdQI8zhVHHl3lUVtHbnbnKqB6wmfMpRlhfdISsvLSbK9PMmc_euSyN-sd-2bGn-_"
+    "gGUfq3l5kvyhddcwhbA81KTrTW8cl3qg9lDnjhfL5ZpgW9qTt_KDnrP9xgQ8e0m-y39YFLsxN4hxoEkkayYXcbg-"
+    "TLGznukoHjpzn3qgqJTV2ogJXaK6ctqTgxKUoPyfUeqmx4szeRJuj3josnbUu0O57kcXXX-bi25IozxSONDzF5jalI4";
+const char *gzip_bomb = gzip_bomb_arr;
+const size_t gzip_bomb_size = sizeof(gzip_bomb_arr) - 1;
+}  // namespace td
diff --git a/libs/tdlib/td/test/data.h b/libs/tdlib/td/test/data.h
new file mode 100644
index 0000000000..c447d5cba6
--- /dev/null
+++ b/libs/tdlib/td/test/data.h
@@ -0,0 +1,15 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/utils/common.h"
+namespace td {
+extern const char *thumbnail;
+extern const size_t thumbnail_size;
+
+extern const char *gzip_bomb;
+extern const size_t gzip_bomb_size;
+}  // namespace td
diff --git a/libs/tdlib/td/test/db.cpp b/libs/tdlib/td/test/db.cpp
new file mode 100644
index 0000000000..8917dd65b8
--- /dev/null
+++ b/libs/tdlib/td/test/db.cpp
@@ -0,0 +1,575 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/db/binlog/BinlogHelper.h"
+#include "td/db/BinlogKeyValue.h"
+#include "td/db/SeqKeyValue.h"
+#include "td/db/SqliteKeyValue.h"
+#include "td/db/SqliteKeyValueSafe.h"
+#include "td/db/TsSeqKeyValue.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/port/thread.h"
+#include "td/utils/Random.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/tests.h"
+
+#include <limits>
+#include <map>
+#include <memory>
+
+REGISTER_TESTS(db);
+
+using namespace td;
+
+template <class ContainerT>
+static typename ContainerT::value_type &rand_elem(ContainerT &cont) {
+  CHECK(0 < cont.size() && cont.size() <= static_cast<size_t>(std::numeric_limits<int>::max()));
+  return cont[Random::fast(0, static_cast<int>(cont.size()) - 1)];
+}
+
+TEST(DB, binlog_encryption) {
+  CSlice binlog_name = "test_binlog";
+  Binlog::destroy(binlog_name).ignore();
+
+  auto hello = DbKey::raw_key(std::string(32, 'A'));
+  auto cucumber = DbKey::password("cucumber");
+  auto empty = DbKey::empty();
+  auto long_data = string(10000, 'Z');
+  {
+    Binlog binlog;
+    binlog.init(binlog_name.str(), [](const BinlogEvent &x) {}).ensure();
+    binlog.add_raw_event(BinlogEvent::create_raw(binlog.next_id(), 1, 0, create_storer("AAAA")));
+    binlog.add_raw_event(BinlogEvent::create_raw(binlog.next_id(), 1, 0, create_storer("BBBB")));
+    binlog.add_raw_event(BinlogEvent::create_raw(binlog.next_id(), 1, 0, create_storer(long_data)));
+    LOG(INFO) << "SET PASSWORD";
+    binlog.change_key(cucumber);
+    binlog.change_key(hello);
+    LOG(INFO) << "OK";
+    binlog.add_raw_event(BinlogEvent::create_raw(binlog.next_id(), 1, 0, create_storer("CCCC")));
+    binlog.close().ensure();
+  }
+
+  auto add_suffix = [&] {
+    auto fd = FileFd::open(binlog_name, FileFd::Flags::Write | FileFd::Flags::Append).move_as_ok();
+    fd.write("abacabadaba").ensure();
+  };
+
+  add_suffix();
+
+  {
+    std::vector<string> v;
+    LOG(INFO) << "RESTART";
+    Binlog binlog;
+    binlog.init(binlog_name.str(), [&](const BinlogEvent &x) { v.push_back(x.data_.str()); }, hello).ensure();
+    CHECK(v == std::vector<string>({"AAAA", "BBBB", long_data, "CCCC"}));
+  }
+
+  add_suffix();
+
+  {
+    std::vector<string> v;
+    LOG(INFO) << "RESTART";
+    Binlog binlog;
+    auto status = binlog.init(binlog_name.str(), [&](const BinlogEvent &x) { v.push_back(x.data_.str()); }, cucumber);
+    CHECK(status.is_error());
+  }
+
+  add_suffix();
+
+  {
+    std::vector<string> v;
+    LOG(INFO) << "RESTART";
+    Binlog binlog;
+    auto status =
+        binlog.init(binlog_name.str(), [&](const BinlogEvent &x) { v.push_back(x.data_.str()); }, cucumber, hello);
+    CHECK(v == std::vector<string>({"AAAA", "BBBB", long_data, "CCCC"}));
+  }
+};
+
+TEST(DB, sqlite_lfs) {
+  string path = "test_sqlite_db";
+  SqliteDb::destroy(path).ignore();
+  SqliteDb db;
+  db.init(path).ensure();
+  db.exec("PRAGMA journal_mode=WAL").ensure();
+  db.exec("PRAGMA user_version").ensure();
+}
+
+TEST(DB, sqlite_encryption) {
+  string path = "test_sqlite_db";
+  SqliteDb::destroy(path).ignore();
+
+  auto empty = DbKey::empty();
+  auto cucumber = DbKey::password("cucumber");
+  auto tomato = DbKey::raw_key(string(32, 'a'));
+
+  {
+    auto db = SqliteDb::open_with_key(path, empty).move_as_ok();
+    db.set_user_version(123);
+    auto kv = SqliteKeyValue();
+    kv.init_with_connection(db.clone(), "kv");
+    kv.set("a", "b");
+  }
+  SqliteDb::open_with_key(path, cucumber).ensure_error();  // key was set...
+
+  SqliteDb::change_key(path, cucumber, empty).ensure();
+
+  SqliteDb::open_with_key(path, tomato).ensure_error();
+  {
+    auto db = SqliteDb::open_with_key(path, cucumber).move_as_ok();
+    auto kv = SqliteKeyValue();
+    kv.init_with_connection(db.clone(), "kv");
+    CHECK(kv.get("a") == "b");
+    CHECK(db.user_version().ok() == 123);
+  }
+
+  SqliteDb::change_key(path, tomato, cucumber).ensure();
+  SqliteDb::change_key(path, tomato, cucumber).ensure();
+
+  SqliteDb::open_with_key(path, cucumber).ensure_error();
+  {
+    auto db = SqliteDb::open_with_key(path, tomato).move_as_ok();
+    auto kv = SqliteKeyValue();
+    kv.init_with_connection(db.clone(), "kv");
+    CHECK(kv.get("a") == "b");
+    CHECK(db.user_version().ok() == 123);
+  }
+
+  SqliteDb::change_key(path, empty, tomato).ensure();
+  SqliteDb::change_key(path, empty, tomato).ensure();
+
+  {
+    auto db = SqliteDb::open_with_key(path, empty).move_as_ok();
+    auto kv = SqliteKeyValue();
+    kv.init_with_connection(db.clone(), "kv");
+    CHECK(kv.get("a") == "b");
+    CHECK(db.user_version().ok() == 123);
+  }
+  SqliteDb::open_with_key(path, cucumber).ensure_error();
+}
+
+using SeqNo = uint64;
+struct DbQuery {
+  enum Type { Get, Set, Erase } type;
+  SeqNo tid = 0;
+  int32 id = 0;
+  string key;
+  string value;
+};
+
+template <class ImplT>
+class QueryHandler {
+ public:
+  ImplT &impl() {
+    return impl_;
+  }
+  void do_query(DbQuery &query) {
+    switch (query.type) {
+      case DbQuery::Get:
+        query.value = impl_.get(query.key);
+        return;
+      case DbQuery::Set:
+        query.tid = impl_.set(query.key, query.value);
+        return;
+      case DbQuery::Erase:
+        query.tid = impl_.erase(query.key);
+        return;
+    }
+  }
+
+ private:
+  ImplT impl_;
+};
+
+class SqliteKV {
+ public:
+  string get(string key) {
+    return kv_->get().get(key);
+  }
+  SeqNo set(string key, string value) {
+    kv_->get().set(key, value);
+    return 0;
+  }
+  SeqNo erase(string key) {
+    kv_->get().erase(key);
+    return 0;
+  }
+  Status init(string name) {
+    auto sql_connection = std::make_shared<SqliteConnectionSafe>(name);
+    kv_ = std::make_shared<SqliteKeyValueSafe>("kv", sql_connection);
+    return Status::OK();
+  }
+  void close() {
+    kv_.reset();
+  }
+
+ private:
+  std::shared_ptr<SqliteKeyValueSafe> kv_;
+};
+
+class BaselineKV {
+ public:
+  string get(string key) {
+    return map_[key];
+  }
+  SeqNo set(string key, string value) {
+    map_[key] = value;
+    return ++current_tid_;
+  }
+  SeqNo erase(string key) {
+    map_.erase(key);
+    return ++current_tid_;
+  }
+
+ private:
+  std::map<string, string> map_;
+  SeqNo current_tid_ = 0;
+};
+
+TEST(DB, key_value) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(INFO));
+  std::vector<std::string> keys;
+  std::vector<std::string> values;
+
+  for (int i = 0; i < 100; i++) {
+    keys.push_back(rand_string('a', 'b', Random::fast(1, 10)));
+  }
+  for (int i = 0; i < 1000; i++) {
+    values.push_back(rand_string('a', 'b', Random::fast(1, 10)));
+  }
+
+  int queries_n = 300000;
+  std::vector<DbQuery> queries(queries_n);
+  for (auto &q : queries) {
+    int op = Random::fast(0, 2);
+    const auto &key = rand_elem(keys);
+    const auto &value = rand_elem(values);
+    if (op == 0) {
+      q.type = DbQuery::Get;
+      q.key = key;
+    } else if (op == 1) {
+      q.type = DbQuery::Erase;
+      q.key = key;
+    } else if (op == 2) {
+      q.type = DbQuery::Set;
+      q.key = key;
+      q.value = value;
+    }
+  }
+
+  QueryHandler<BaselineKV> baseline;
+  QueryHandler<SeqKeyValue> kv;
+  QueryHandler<TsSeqKeyValue> ts_kv;
+  QueryHandler<BinlogKeyValue<Binlog>> new_kv;
+
+  CSlice new_kv_name = "test_new_kv";
+  Binlog::destroy(new_kv_name).ignore();
+  new_kv.impl().init(new_kv_name.str()).ensure();
+
+  QueryHandler<SqliteKeyValue> sqlite_kv;
+  CSlice name = "test_sqlite_kv";
+  SqliteDb::destroy(name).ignore();
+  sqlite_kv.impl().init(name.str()).ensure();
+
+  int cnt = 0;
+  for (auto &q : queries) {
+    DbQuery a = q;
+    DbQuery b = q;
+    DbQuery c = q;
+    DbQuery d = q;
+    DbQuery e = q;
+    baseline.do_query(a);
+    kv.do_query(b);
+    ts_kv.do_query(c);
+    sqlite_kv.do_query(d);
+    new_kv.do_query(e);
+    ASSERT_EQ(a.value, b.value);
+    ASSERT_EQ(a.value, c.value);
+    ASSERT_EQ(a.value, d.value);
+    ASSERT_EQ(a.value, e.value);
+    if (cnt++ % 10000 == 0) {
+      new_kv.impl().init(new_kv_name.str()).ensure();
+    }
+  }
+}
+
+TEST(DB, thread_key_value) {
+#if !TD_THREAD_UNSUPPORTED
+  std::vector<std::string> keys;
+  std::vector<std::string> values;
+
+  for (int i = 0; i < 100; i++) {
+    keys.push_back(rand_string('a', 'b', Random::fast(1, 10)));
+  }
+  for (int i = 0; i < 1000; i++) {
+    values.push_back(rand_string('a', 'b', Random::fast(1, 10)));
+  }
+
+  int threads_n = 4;
+  int queries_n = 100000;
+
+  std::vector<std::vector<DbQuery>> queries(threads_n, std::vector<DbQuery>(queries_n));
+  for (auto &qs : queries) {
+    for (auto &q : qs) {
+      int op = Random::fast(0, 10);
+      const auto &key = rand_elem(keys);
+      const auto &value = rand_elem(values);
+      if (op > 1) {
+        q.type = DbQuery::Get;
+        q.key = key;
+      } else if (op == 0) {
+        q.type = DbQuery::Erase;
+        q.key = key;
+      } else if (op == 1) {
+        q.type = DbQuery::Set;
+        q.key = key;
+        q.value = value;
+      }
+    }
+  }
+
+  QueryHandler<BaselineKV> baseline;
+  QueryHandler<TsSeqKeyValue> ts_kv;
+
+  std::vector<thread> threads(threads_n);
+  std::vector<std::vector<DbQuery>> res(threads_n);
+  for (int i = 0; i < threads_n; i++) {
+    threads[i] = thread([&ts_kv, &queries, &res, i]() {
+      for (auto q : queries[i]) {
+        ts_kv.do_query(q);
+        res[i].push_back(q);
+      }
+    });
+  }
+  for (auto &thread : threads) {
+    thread.join();
+  }
+
+  std::vector<std::size_t> pos(threads_n);
+  while (true) {
+    bool was = false;
+    for (int i = 0; i < threads_n; i++) {
+      auto p = pos[i];
+      if (p == res[i].size()) {
+        continue;
+      }
+      auto &q = res[i][p];
+      if (q.tid == 0) {
+        if (q.type == DbQuery::Get) {
+          auto nq = q;
+          baseline.do_query(nq);
+          if (nq.value == q.value) {
+            was = true;
+            pos[i]++;
+          }
+        } else {
+          was = true;
+          pos[i]++;
+        }
+      }
+    }
+    if (was) {
+      continue;
+    }
+
+    int best = -1;
+    SeqNo best_tid = 0;
+    for (int i = 0; i < threads_n; i++) {
+      auto p = pos[i];
+      if (p == res[i].size()) {
+        continue;
+      }
+      was = true;
+      auto &q = res[i][p];
+      if (q.tid != 0) {
+        if (best == -1 || q.tid < best_tid) {
+          best = i;
+          best_tid = q.tid;
+        }
+      }
+    }
+    if (!was) {
+      break;
+    }
+    ASSERT_TRUE(best != -1);
+    baseline.do_query(res[best][pos[best]]);
+    pos[best]++;
+  }
+#endif
+}
+
+TEST(DB, persistent_key_value) {
+  using KeyValue = BinlogKeyValue<ConcurrentBinlog>;
+  // using KeyValue = PersistentKeyValue;
+  // using KeyValue = SqliteKV;
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(WARNING));
+  std::vector<std::string> keys;
+  std::vector<std::string> values;
+  CSlice name = "test_pmc";
+  Binlog::destroy(name).ignore();
+  SqliteDb::destroy(name).ignore();
+
+  for (int i = 0; i < 100; i++) {
+    keys.push_back(rand_string('a', 'b', Random::fast(1, 10)));
+  }
+  for (int i = 0; i < 1000; i++) {
+    values.push_back(rand_string('a', 'b', Random::fast(1, 10)));
+  }
+
+  QueryHandler<BaselineKV> baseline;
+
+  for (int iter = 0; iter < 25; iter++) {
+    int threads_n = 4;
+    int queries_n = 3000 / threads_n;
+
+    std::vector<std::vector<DbQuery>> queries(threads_n, std::vector<DbQuery>(queries_n));
+    for (auto &qs : queries) {
+      for (auto &q : qs) {
+        int op = Random::fast(0, 10);
+        const auto &key = rand_elem(keys);
+        const auto &value = rand_elem(values);
+        if (op > 1) {
+          q.type = DbQuery::Get;
+          q.key = key;
+        } else if (op == 0) {
+          q.type = DbQuery::Erase;
+          q.key = key;
+        } else if (op == 1) {
+          q.type = DbQuery::Set;
+          q.key = key;
+          q.value = value;
+        }
+      }
+    }
+
+    std::vector<std::vector<DbQuery>> res(threads_n);
+    class Worker : public Actor {
+     public:
+      Worker(ActorShared<> parent, std::shared_ptr<QueryHandler<KeyValue>> kv, const std::vector<DbQuery> *queries,
+             std::vector<DbQuery> *res)
+          : parent_(std::move(parent)), kv_(std::move(kv)), queries_(queries), res_(res) {
+      }
+      void loop() override {
+        for (auto q : *queries_) {
+          kv_->do_query(q);
+          res_->push_back(q);
+        }
+        stop();
+      }
+
+     private:
+      ActorShared<> parent_;
+      std::shared_ptr<QueryHandler<KeyValue>> kv_;
+      const std::vector<DbQuery> *queries_;
+      std::vector<DbQuery> *res_;
+    };
+    class Main : public Actor {
+     public:
+      Main(int threads_n, const std::vector<std::vector<DbQuery>> *queries, std::vector<std::vector<DbQuery>> *res)
+          : threads_n_(threads_n), queries_(queries), res_(res) {
+      }
+
+      void start_up() override {
+        LOG(INFO) << "start_up";
+        kv_->impl().init("test_pmc").ensure();
+        ref_cnt_ = threads_n_;
+        for (int i = 0; i < threads_n_; i++) {
+          create_actor_on_scheduler<Worker>("Worker", i + 1, actor_shared(this, 2), kv_, &queries_->at(i), &res_->at(i))
+              .release();
+        }
+      }
+
+      void tear_down() override {
+        LOG(INFO) << "tear_down";
+        // kv_->impl().close();
+      }
+      void hangup_shared() override {
+        LOG(INFO) << "hangup";
+        ref_cnt_--;
+        if (ref_cnt_ == 0) {
+          kv_->impl().close();
+          Scheduler::instance()->finish();
+          stop();
+        }
+      }
+      void hangup() override {
+        LOG(ERROR) << "BAD HANGUP";
+      }
+
+     private:
+      int threads_n_;
+      const std::vector<std::vector<DbQuery>> *queries_;
+      std::vector<std::vector<DbQuery>> *res_;
+
+      std::shared_ptr<QueryHandler<KeyValue>> kv_{new QueryHandler<KeyValue>()};
+      int ref_cnt_;
+    };
+
+    ConcurrentScheduler sched;
+    sched.init(threads_n);
+    sched.create_actor_unsafe<Main>(0, "Main", threads_n, &queries, &res).release();
+    sched.start();
+    while (sched.run_main(10)) {
+      // empty
+    }
+    sched.finish();
+
+    std::vector<std::size_t> pos(threads_n);
+    while (true) {
+      bool was = false;
+      for (int i = 0; i < threads_n; i++) {
+        auto p = pos[i];
+        if (p == res[i].size()) {
+          continue;
+        }
+        auto &q = res[i][p];
+        if (q.tid == 0) {
+          if (q.type == DbQuery::Get) {
+            auto nq = q;
+            baseline.do_query(nq);
+            if (nq.value == q.value) {
+              was = true;
+              pos[i]++;
+            }
+          } else {
+            was = true;
+            pos[i]++;
+          }
+        }
+      }
+      if (was) {
+        continue;
+      }
+
+      int best = -1;
+      SeqNo best_tid = 0;
+      for (int i = 0; i < threads_n; i++) {
+        auto p = pos[i];
+        if (p == res[i].size()) {
+          continue;
+        }
+        was = true;
+        auto &q = res[i][p];
+        if (q.tid != 0) {
+          if (best == -1 || q.tid < best_tid) {
+            best = i;
+            best_tid = q.tid;
+          }
+        }
+      }
+      if (!was) {
+        break;
+      }
+      ASSERT_TRUE(best != -1);
+      baseline.do_query(res[best][pos[best]]);
+      pos[best]++;
+    }
+  }
+}
diff --git a/libs/tdlib/td/test/fuzz_url.cpp b/libs/tdlib/td/test/fuzz_url.cpp
new file mode 100644
index 0000000000..74047135c0
--- /dev/null
+++ b/libs/tdlib/td/test/fuzz_url.cpp
@@ -0,0 +1,33 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/MessageEntity.h"
+
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/Slice.h"
+
+#include <cstddef>
+#include <cstdint>
+
+static td::string get_utf_string(td::Slice from) {
+  td::string res;
+  td::string alph = " ab@./01#";
+  for (auto c : from) {
+    res += alph[td::uint8(c) % alph.size()];
+  }
+  LOG(ERROR) << res;
+  return res;
+}
+
+extern "C" int LLVMFuzzerTestOneInput(std::uint8_t *data, std::size_t data_size) {
+  td::find_urls(get_utf_string(td::Slice(data, data_size)));
+  //td::find_hashtags(get_utf_string(td::Slice(data, data_size)));
+  //td::find_bot_commands(get_utf_string(td::Slice(data, data_size)));
+  //td::is_email_address(get_utf_string(td::Slice(data, data_size)));
+  //td::find_mentions(get_utf_string(td::Slice(data, data_size)));
+  return 0;
+}
diff --git a/libs/tdlib/td/test/http.cpp b/libs/tdlib/td/test/http.cpp
new file mode 100644
index 0000000000..98c94b2e8a
--- /dev/null
+++ b/libs/tdlib/td/test/http.cpp
@@ -0,0 +1,373 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/tests.h"
+
+#include "td/net/HttpChunkedByteFlow.h"
+#include "td/net/HttpHeaderCreator.h"
+#include "td/net/HttpQuery.h"
+#include "td/net/HttpReader.h"
+
+#include "td/utils/AesCtrByteFlow.h"
+#include "td/utils/base64.h"
+#include "td/utils/buffer.h"
+#include "td/utils/BufferedFd.h"
+#include "td/utils/ByteFlow.h"
+#include "td/utils/crypto.h"
+#include "td/utils/format.h"
+#include "td/utils/Gzip.h"
+#include "td/utils/GzipByteFlow.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/Fd.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/port/path.h"
+#include "td/utils/port/thread_local.h"
+#include "td/utils/Random.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+#include "test/data.h"
+
+#include <algorithm>
+#include <cstdlib>
+#include <limits>
+
+REGISTER_TESTS(http)
+
+using namespace td;
+
+static string make_chunked(string str) {
+  auto v = rand_split(str);
+  string res;
+  for (auto &s : v) {
+    res += PSTRING() << format::as_hex_dump(int(s.size()));
+    res += "\r\n";
+    res += s;
+    res += "\r\n";
+  }
+  res += "0\r\n\r\n";
+  return res;
+}
+
+static string gen_http_content() {
+  int t = Random::fast(0, 2);
+  int len;
+  if (t == 0) {
+    len = Random::fast(1, 10);
+  } else if (t == 1) {
+    len = Random::fast(100, 200);
+  } else {
+    len = Random::fast(1000, 20000);
+  }
+  return rand_string(std::numeric_limits<char>::min(), std::numeric_limits<char>::max(), len);
+}
+
+static string make_http_query(string content, bool is_chunked, bool is_gzip, double gzip_k = 5,
+                              string zip_override = "") {
+  HttpHeaderCreator hc;
+  hc.init_post("/");
+  hc.add_header("jfkdlsahhjk", rand_string('a', 'z', Random::fast(1, 2000)));
+  if (is_gzip) {
+    BufferSlice zip;
+    if (zip_override.empty()) {
+      zip = gzencode(content, gzip_k);
+    } else {
+      zip = BufferSlice(zip_override);
+    }
+    if (!zip.empty()) {
+      hc.add_header("content-encoding", "gzip");
+      content = zip.as_slice().str();
+    }
+  }
+  if (is_chunked) {
+    hc.add_header("transfer-encoding", "chunked");
+    content = make_chunked(content);
+  } else {
+    hc.set_content_size(content.size());
+  }
+  string res;
+  auto r_header = hc.finish();
+  CHECK(r_header.is_ok());
+  res += r_header.ok().str();
+  res += content;
+  return res;
+}
+
+static string rand_http_query(string content) {
+  bool is_chunked = Random::fast(0, 1) == 0;
+  bool is_gzip = Random::fast(0, 1) == 0;
+  return make_http_query(std::move(content), is_chunked, is_gzip);
+}
+
+static string join(const std::vector<string> &v) {
+  string res;
+  for (auto &s : v) {
+    res += s;
+  }
+  return res;
+}
+
+TEST(Http, stack_overflow) {
+  ChainBufferWriter writer;
+  BufferSlice slice(string(256, 'A'));
+  for (int i = 0; i < 1000000; i++) {
+    ChainBufferWriter tmp_writer;
+    writer.append(slice.clone());
+  }
+  {
+    auto reader = writer.extract_reader();
+    reader.sync_with_writer();
+  }
+}
+
+TEST(Http, reader) {
+#if TD_ANDROID || TD_TIZEN
+  return;
+#endif
+  clear_thread_locals();
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(INFO));
+  auto start_mem = BufferAllocator::get_buffer_mem();
+  {
+    auto input_writer = ChainBufferWriter::create_empty();
+    auto input = input_writer.extract_reader();
+    HttpReader reader;
+    int max_post_size = 10000;
+    reader.init(&input, max_post_size, 0);
+
+    std::srand(4);
+    std::vector<string> contents(1000);
+    std::generate(contents.begin(), contents.end(), gen_http_content);
+    auto v = td::transform(contents, rand_http_query);
+    auto vec_str = rand_split(join(v));
+
+    HttpQuery q;
+    std::vector<string> res;
+    for (auto &str : vec_str) {
+      input_writer.append(str);
+      input.sync_with_writer();
+      while (true) {
+        auto r_state = reader.read_next(&q);
+        LOG_IF(ERROR, r_state.is_error()) << r_state.error() << tag("ok", res.size());
+        ASSERT_TRUE(r_state.is_ok());
+        auto state = r_state.ok();
+        if (state == 0) {
+          if (q.files_.empty()) {
+            ASSERT_TRUE(td::narrow_cast<int>(q.content_.size()) <= max_post_size);
+            auto expected = contents[res.size()];
+            ASSERT_EQ(expected, q.content_.str());
+            res.push_back(q.content_.str());
+          } else {
+            auto r_fd = FileFd::open(q.files_[0].temp_file_name, FileFd::Read);
+            ASSERT_TRUE(r_fd.is_ok());
+            auto fd = r_fd.move_as_ok();
+            string content(td::narrow_cast<size_t>(q.files_[0].size), '\0');
+            auto r_size = fd.read(MutableSlice(content));
+            ASSERT_TRUE(r_size.is_ok());
+            ASSERT_TRUE(r_size.ok() == content.size());
+            ASSERT_TRUE(td::narrow_cast<int>(content.size()) > max_post_size);
+            ASSERT_EQ(contents[res.size()], content);
+            res.push_back(content);
+            fd.close();
+          }
+        } else {
+          break;
+        }
+      }
+    }
+    ASSERT_EQ(contents.size(), res.size());
+    ASSERT_EQ(contents, res);
+  }
+  clear_thread_locals();
+  ASSERT_EQ(start_mem, BufferAllocator::get_buffer_mem());
+}
+
+TEST(Http, gzip_bomb) {
+#if TD_ANDROID || TD_TIZEN || TD_EMSCRIPTEN  // the test should be disabled on low-memory systems
+  return;
+#endif
+  auto gzip_bomb_str =
+      gzdecode(gzdecode(base64url_decode(Slice(gzip_bomb, gzip_bomb_size)).ok()).as_slice()).as_slice().str();
+
+  auto query = make_http_query("", false, true, 0.01, gzip_bomb_str);
+  auto parts = rand_split(query);
+  auto input_writer = ChainBufferWriter::create_empty();
+  auto input = input_writer.extract_reader();
+  HttpReader reader;
+  HttpQuery q;
+  reader.init(&input, 100000000, 0);
+  for (auto &part : parts) {
+    input_writer.append(part);
+    input.sync_with_writer();
+    auto r_state = reader.read_next(&q);
+    if (r_state.is_error()) {
+      LOG(INFO) << r_state.error();
+      return;
+    }
+    ASSERT_TRUE(r_state.ok() != 0);
+  }
+}
+
+TEST(Http, aes_ctr_encode_decode_flow) {
+  auto str = rand_string('a', 'z', 1000000);
+  auto parts = rand_split(str);
+  auto input_writer = ChainBufferWriter::create_empty();
+  auto input = input_writer.extract_reader();
+  ByteFlowSource source(&input);
+  UInt256 key;
+  UInt128 iv;
+  Random::secure_bytes(key.raw, sizeof(key));
+  Random::secure_bytes(iv.raw, sizeof(iv));
+  AesCtrByteFlow aes_encode;
+  aes_encode.init(key, iv);
+  AesCtrByteFlow aes_decode;
+  aes_decode.init(key, iv);
+  ByteFlowSink sink;
+  source >> aes_encode >> aes_decode >> sink;
+
+  ASSERT_TRUE(!sink.is_ready());
+  for (auto &part : parts) {
+    input_writer.append(part);
+    source.wakeup();
+  }
+  ASSERT_TRUE(!sink.is_ready());
+  source.close_input(Status::OK());
+  ASSERT_TRUE(sink.is_ready());
+  LOG_IF(ERROR, sink.status().is_error()) << sink.status();
+  ASSERT_TRUE(sink.status().is_ok());
+  ASSERT_EQ(str, sink.result()->move_as_buffer_slice().as_slice().str());
+}
+
+TEST(Http, aes_file_encryption) {
+  auto str = rand_string('a', 'z', 1000000);
+  CSlice name = "test_encryption";
+  unlink(name).ignore();
+  UInt256 key;
+  UInt128 iv;
+  Random::secure_bytes(key.raw, sizeof(key));
+  Random::secure_bytes(iv.raw, sizeof(iv));
+
+  {
+    BufferedFdBase<FileFd> fd(FileFd::open(name, FileFd::Write | FileFd::Create).move_as_ok());
+
+    auto parts = rand_split(str);
+
+    ChainBufferWriter output_writer;
+    auto output_reader = output_writer.extract_reader();
+    ByteFlowSource source(&output_reader);
+    AesCtrByteFlow aes_encode;
+    aes_encode.init(key, iv);
+    ByteFlowSink sink;
+
+    source >> aes_encode >> sink;
+    fd.set_output_reader(sink.get_output());
+
+    for (auto &part : parts) {
+      output_writer.append(part);
+      source.wakeup();
+      fd.flush_write().ensure();
+    }
+    fd.close();
+  }
+
+  {
+    BufferedFdBase<FileFd> fd(FileFd::open(name, FileFd::Read).move_as_ok());
+
+    ChainBufferWriter input_writer;
+    auto input_reader = input_writer.extract_reader();
+    ByteFlowSource source(&input_reader);
+    AesCtrByteFlow aes_encode;
+    aes_encode.init(key, iv);
+    ByteFlowSink sink;
+    source >> aes_encode >> sink;
+    fd.set_input_writer(&input_writer);
+
+    fd.update_flags(Fd::Flag::Read);
+    while (can_read(fd)) {
+      fd.flush_read(4096).ensure();
+      source.wakeup();
+    }
+
+    fd.close();
+
+    source.close_input(Status::OK());
+    ASSERT_TRUE(sink.is_ready());
+    LOG_IF(ERROR, sink.status().is_error()) << sink.status();
+    ASSERT_TRUE(sink.status().is_ok());
+    auto result = sink.result()->move_as_buffer_slice().as_slice().str();
+    ASSERT_EQ(str, result);
+  }
+}
+
+TEST(Http, chunked_flow) {
+  auto str = rand_string('a', 'z', 100);
+  auto parts = rand_split(make_chunked(str));
+  auto input_writer = ChainBufferWriter::create_empty();
+  auto input = input_writer.extract_reader();
+  ByteFlowSource source(&input);
+  HttpChunkedByteFlow chunked_flow;
+  ByteFlowSink sink;
+  source >> chunked_flow >> sink;
+
+  for (auto &part : parts) {
+    input_writer.append(part);
+    source.wakeup();
+  }
+  source.close_input(Status::OK());
+  ASSERT_TRUE(sink.is_ready());
+  LOG_IF(ERROR, sink.status().is_error()) << sink.status();
+  ASSERT_TRUE(sink.status().is_ok());
+  auto res = sink.result()->move_as_buffer_slice().as_slice().str();
+  ASSERT_EQ(str.size(), res.size());
+  ASSERT_EQ(str, res);
+}
+
+TEST(Http, chunked_flow_error) {
+  auto str = rand_string('a', 'z', 100000);
+  for (int d = 1; d < 100; d += 10) {
+    auto new_str = make_chunked(str);
+    new_str.resize(str.size() - d);
+    auto parts = rand_split(new_str);
+    auto input_writer = ChainBufferWriter::create_empty();
+    auto input = input_writer.extract_reader();
+    ByteFlowSource source(&input);
+    HttpChunkedByteFlow chunked_flow;
+    ByteFlowSink sink;
+    source >> chunked_flow >> sink;
+
+    for (auto &part : parts) {
+      input_writer.append(part);
+      source.wakeup();
+    }
+    ASSERT_TRUE(!sink.is_ready());
+    source.close_input(Status::OK());
+    ASSERT_TRUE(sink.is_ready());
+    ASSERT_TRUE(!sink.status().is_ok());
+  }
+}
+
+TEST(Http, gzip_chunked_flow) {
+  auto str = rand_string('a', 'z', 1000000);
+  auto parts = rand_split(make_chunked(gzencode(str).as_slice().str()));
+
+  auto input_writer = ChainBufferWriter::create_empty();
+  auto input = input_writer.extract_reader();
+  ByteFlowSource source(&input);
+  HttpChunkedByteFlow chunked_flow;
+  GzipByteFlow gzip_flow(Gzip::Decode);
+  ByteFlowSink sink;
+  source >> chunked_flow >> gzip_flow >> sink;
+
+  for (auto &part : parts) {
+    input_writer.append(part);
+    source.wakeup();
+  }
+  source.close_input(Status::OK());
+  ASSERT_TRUE(sink.is_ready());
+  LOG_IF(ERROR, sink.status().is_error()) << sink.status();
+  ASSERT_TRUE(sink.status().is_ok());
+  ASSERT_EQ(str, sink.result()->move_as_buffer_slice().as_slice().str());
+}
diff --git a/libs/tdlib/td/test/main.cpp b/libs/tdlib/td/test/main.cpp
new file mode 100644
index 0000000000..0ef46c75b2
--- /dev/null
+++ b/libs/tdlib/td/test/main.cpp
@@ -0,0 +1,40 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/tests.h"
+
+#include "td/utils/logging.h"
+
+#include <cstring>
+
+#if TD_EMSCRIPTEN
+#include <emscripten.h>
+#endif
+
+int main(int argc, char **argv) {
+  // TODO port OptionsParser to Windows
+  for (int i = 1; i < argc; i++) {
+    if (!std::strcmp(argv[i], "--filter")) {
+      CHECK(i + 1 < argc);
+      td::Test::add_substr_filter(argv[++i]);
+    }
+    if (!std::strcmp(argv[i], "--stress")) {
+      td::Test::set_stress_flag(true);
+    }
+  }
+#if TD_EMSCRIPTEN
+  emscripten_set_main_loop(
+      [] {
+        if (!td::Test::run_all_step()) {
+          emscripten_cancel_main_loop();
+        }
+      },
+      10, 0);
+#else
+  td::Test::run_all();
+#endif
+  return 0;
+}
diff --git a/libs/tdlib/td/test/message_entities.cpp b/libs/tdlib/td/test/message_entities.cpp
new file mode 100644
index 0000000000..473a87140a
--- /dev/null
+++ b/libs/tdlib/td/test/message_entities.cpp
@@ -0,0 +1,529 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/MessageEntity.h"
+
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/tests.h"
+
+REGISTER_TESTS(message_entities);
+
+using namespace td;
+
+static void check_mention(string str, std::vector<string> expected) {
+  auto result_slice = find_mentions(str);
+  std::vector<string> result;
+  for (auto &it : result_slice) {
+    result.push_back(it.str());
+  }
+  if (result != expected) {
+    LOG(FATAL) << tag("text", str) << tag("got", format::as_array(result))
+               << tag("expected", format::as_array(expected));
+  }
+}
+
+TEST(MessageEntities, mention) {
+  check_mention("@mention", {"@mention"});
+  check_mention("@mention ", {"@mention"});
+  check_mention(" @mention", {"@mention"});
+  check_mention(" @mention ", {"@mention"});
+  check_mention("@abc @xyz @abc @xyz @xxx@yyy @ttt", {});
+  check_mention("@abcde @xyzxy @abcde @xyzxy @xxxxx@yyyyy @ttttt",
+                {"@abcde", "@xyzxy", "@abcde", "@xyzxy", "@xxxxx", "@ttttt"});
+  check_mention("no@mention", {});
+  check_mention("@n", {});
+  check_mention("@abcdefghijklmnopqrstuvwxyz123456", {"@abcdefghijklmnopqrstuvwxyz123456"});
+  check_mention("@abcdefghijklmnopqrstuvwxyz1234567", {});
+  check_mention("нет@mention", {});
+  check_mention("@ya @gif @wiki @vid @bing @pic @bold @imdb @coub @like @vote @giff @cap ya cap @y @yar @bingg @bin",
+                {"@ya", "@gif", "@wiki", "@vid", "@bing", "@pic", "@bold", "@imdb", "@coub", "@like", "@vote", "@giff",
+                 "@cap", "@bingg"});
+};
+
+static void check_bot_command(string str, std::vector<string> expected) {
+  auto result_slice = find_bot_commands(str);
+  std::vector<string> result;
+  for (auto &it : result_slice) {
+    result.push_back(it.str());
+  }
+  if (result != expected) {
+    LOG(FATAL) << tag("text", str) << tag("got", format::as_array(result))
+               << tag("expected", format::as_array(expected));
+  }
+}
+
+TEST(MessageEntities, bot_command) {
+  // 1..64@3..32
+  check_bot_command("/abc", {"/abc"});
+  check_bot_command(" /abc", {"/abc"});
+  check_bot_command("/abc ", {"/abc"});
+  check_bot_command(" /abc ", {"/abc"});
+  check_bot_command("/a@abc", {"/a@abc"});
+  check_bot_command("/a@b", {});
+  check_bot_command("/@bfdsa", {});
+  check_bot_command("/test/", {});
+}
+
+static void check_hashtag(string str, std::vector<string> expected) {
+  auto result_slice = find_hashtags(str);
+  std::vector<string> result;
+  for (auto &it : result_slice) {
+    result.push_back(it.str());
+  }
+  if (result != expected) {
+    LOG(FATAL) << tag("text", str) << tag("got", format::as_array(result))
+               << tag("expected", format::as_array(expected));
+  }
+}
+
+TEST(MessageEntities, hashtag) {
+  check_hashtag("", {});
+  check_hashtag("#", {});
+  check_hashtag("##", {});
+  check_hashtag("###", {});
+  check_hashtag("#a", {"#a"});
+  check_hashtag(" #a", {"#a"});
+  check_hashtag("#a ", {"#a"});
+  check_hashtag(" #я ", {"#я"});
+  check_hashtag(" я#a ", {});
+  check_hashtag(" #a# ", {});
+  check_hashtag(" #123 ", {});
+  check_hashtag(" #123a ", {"#123a"});
+  check_hashtag(" #a123 ", {"#a123"});
+  check_hashtag(" #123a# ", {});
+  check_hashtag(" #" + string(300, '1'), {});
+  check_hashtag(" #" + string(256, '1'), {});
+  check_hashtag(" #" + string(256, '1') + "a ", {});
+  check_hashtag(" #" + string(255, '1') + "a", {"#" + string(255, '1') + "a"});
+  check_hashtag(" #" + string(255, '1') + "Я", {"#" + string(255, '1') + "Я"});
+  check_hashtag(" #" + string(255, '1') + "a" + string(255, 'b') + "# ", {});
+  check_hashtag("#a#b #c #d", {"#c", "#d"});
+  check_hashtag("#test", {"#test"});
+  check_hashtag(u8"\U0001F604\U0001F604\U0001F604\U0001F604 \U0001F604\U0001F604\U0001F604#" + string(200, '1') +
+                    "ООО" + string(200, '2'),
+                {"#" + string(200, '1') + "ООО" + string(53, '2')});
+  check_hashtag(u8"#a\u2122", {"#a"});
+}
+
+static void check_cashtag(string str, std::vector<string> expected) {
+  auto result_slice = find_cashtags(str);
+  std::vector<string> result;
+  for (auto &it : result_slice) {
+    result.push_back(it.str());
+  }
+  if (result != expected) {
+    LOG(FATAL) << tag("text", str) << tag("got", format::as_array(result))
+               << tag("expected", format::as_array(expected));
+  }
+}
+
+TEST(MessageEntities, cashtag) {
+  check_cashtag("", {});
+  check_cashtag("$", {});
+  check_cashtag("$$", {});
+  check_cashtag("$$$", {});
+  check_cashtag("$a", {});
+  check_cashtag(" $a", {});
+  check_cashtag("$a ", {});
+  check_cashtag(" $я ", {});
+  check_cashtag("$ab", {});
+  check_cashtag("$abc", {});
+  check_cashtag("$", {});
+  check_cashtag("$A", {});
+  check_cashtag("$AB", {});
+  check_cashtag("$АBC", {});
+  check_cashtag("$АВС", {});
+  check_cashtag("$ABC", {"$ABC"});
+  check_cashtag("$ABCD", {"$ABCD"});
+  check_cashtag("$ABCDE", {"$ABCDE"});
+  check_cashtag("$ABCDEF", {"$ABCDEF"});
+  check_cashtag("$ABCDEFG", {"$ABCDEFG"});
+  check_cashtag("$ABCDEFGH", {"$ABCDEFGH"});
+  check_cashtag("$ABCDEFGHJ", {});
+  check_cashtag("$ABCDEFGH1", {});
+  check_cashtag(" $XYZ", {"$XYZ"});
+  check_cashtag("$XYZ ", {"$XYZ"});
+  check_cashtag(" $XYZ ", {"$XYZ"});
+  check_cashtag(" $$XYZ ", {});
+  check_cashtag(" $XYZ$ ", {});
+  check_cashtag(" $ABC1 ", {});
+  check_cashtag(" $1ABC ", {});
+  check_cashtag(" 1$ABC ", {});
+  check_cashtag(" А$ABC ", {});
+  check_cashtag("$ABC$DEF $GHI $KLM", {"$GHI", "$KLM"});
+  check_cashtag("$TEST", {"$TEST"});
+  check_cashtag(u8"$ABC\u2122", {"$ABC"});
+  check_cashtag(u8"\u2122$ABC", {"$ABC"});
+  check_cashtag(u8"\u2122$ABC\u2122", {"$ABC"});
+}
+
+static void check_is_email_address(string str, bool expected) {
+  bool result = is_email_address(str);
+  LOG_IF(FATAL, result != expected) << "Expected " << expected << " as result of is_email_address(" << str << ")";
+}
+
+TEST(MessageEntities, is_email_address) {
+  check_is_email_address("telegram.org", false);
+  check_is_email_address("security@telegram.org", true);
+  check_is_email_address("security.telegram.org", false);
+  check_is_email_address("", false);
+  check_is_email_address("@", false);
+  check_is_email_address("A@a.a.a.ab", true);
+  check_is_email_address("A@a.ab", true);
+  check_is_email_address("Test@aa.aa.aa.aa", true);
+  check_is_email_address("Test@test.abd", true);
+  check_is_email_address("a@a.a.a.ab", true);
+  check_is_email_address("test@test.abd", true);
+  check_is_email_address("test@test.com", true);
+  check_is_email_address("test.abd", false);
+  check_is_email_address("a.ab", false);
+  check_is_email_address("a.bc@d.ef", true);
+
+  vector<string> bad_userdatas = {"",
+                                  "a.a.a.a.a.a.a.a.a.a.a.a",
+                                  "+.+.+.+.+.+",
+                                  "*.a.a",
+                                  "a.*.a",
+                                  "a.a.*",
+                                  "a.a.",
+                                  "a.a.abcdefghijklmnopqrstuvwxyz0123456789",
+                                  "a.abcdefghijklmnopqrstuvwxyz0.a",
+                                  "abcdefghijklmnopqrstuvwxyz0.a.a"};
+  vector<string> good_userdatas = {"a.a.a.a.a.a.a.a.a.a.a",
+                                   "a+a+a+a+a+a+a+a+a+a+a",
+                                   "+.+.+.+.+._",
+                                   "aozAQZ0-5-9_+-aozAQZ0-5-9_.aozAQZ0-5-9_.-._.+-",
+                                   "a.a.a",
+                                   "a.a.abcdefghijklmnopqrstuvwxyz012345678",
+                                   "a.abcdefghijklmnopqrstuvwxyz.a",
+                                   "a..a",
+                                   "abcdefghijklmnopqrstuvwxyz.a.a",
+                                   ".a.a"};
+
+  vector<string> bad_domains = {"",
+                                ".",
+                                "abc",
+                                "localhost",
+                                "a.a.a.a.a.a.a.ab",
+                                ".......",
+                                "a.a.a.a.a.a+ab",
+                                "a+a.a.a.a.a.ab",
+                                "a.a.a.a.a.a.a",
+                                "a.a.a.a.a.a.abcdefg",
+                                "a.a.a.a.a.a.ab0yz",
+                                "a.a.a.a.a.a.ab9yz",
+                                "a.a.a.a.a.a.ab-yz",
+                                "a.a.a.a.a.a.ab_yz",
+                                "a.a.a.a.a.a.ab*yz",
+                                ".ab",
+                                ".a.ab",
+                                "a..ab",
+                                "a.a.a..a.ab",
+                                ".a.a.a.a.ab",
+                                "abcdefghijklmnopqrstuvwxyz01234.ab",
+                                "ab0cd.abd.aA*sd.0.9.0-9.ABOYZ",
+                                "ab*cd.abd.aAasd.0.9.0-9.ABOYZ",
+                                "ab0cd.abd.aAasd.0.9.0*9.ABOYZ",
+                                "*b0cd.ab_d.aA-sd.0.9.0-9.ABOYZ",
+                                "ab0c*.ab_d.aA-sd.0.9.0-9.ABOYZ",
+                                "ab0cd.ab_d.aA-sd.0.9.0-*.ABOYZ",
+                                "ab0cd.ab_d.aA-sd.0.9.*-9.ABOYZ",
+                                "-b0cd.ab_d.aA-sd.0.9.0-9.ABOYZ",
+                                "ab0c-.ab_d.aA-sd.0.9.0-9.ABOYZ",
+                                "ab0cd.ab_d.aA-sd.-.9.0-9.ABOYZ",
+                                "ab0cd.ab_d.aA-sd.0.9.--9.ABOYZ",
+                                "ab0cd.ab_d.aA-sd.0.9.0--.ABOYZ",
+                                "_b0cd.ab_d.aA-sd.0.9.0-9.ABOYZ",
+                                "ab0c_.ab_d.aA-sd.0.9.0-9.ABOYZ",
+                                "ab0cd.ab_d.aA-sd._.9.0-9.ABOYZ",
+                                "ab0cd.ab_d.aA-sd.0.9._-9.ABOYZ",
+                                "ab0cd.ab_d.aA-sd.0.9.0-_.ABOYZ",
+                                "-.ab_d.aA-sd.0.9.0-9.ABOYZ",
+                                "ab0cd.ab_d.-.0.9.0-9.ABOYZ",
+                                "ab0cd.ab_d.aA-sd.0.9.-.ABOYZ",
+                                "_.ab_d.aA-sd.0.9.0-9.ABOYZ",
+                                "ab0cd.ab_d._.0.9.0-9.ABOYZ",
+                                "ab0cd.ab_d.aA-sd.0.9._.ABOYZ"};
+  vector<string> good_domains = {"a.a.a.a.a.a.ab",
+                                 "a.a.a.a.a.a.abcdef",
+                                 "a.a.a.a.a.a.aboyz",
+                                 "a.a.a.a.a.a.ABOYZ",
+                                 "a.a.a.a.a.a.AbOyZ",
+                                 "abcdefghijklmnopqrstuvwxyz0123.ab",
+                                 "ab0cd.ab_d.aA-sd.0.9.0-9.ABOYZ",
+                                 "A.Z.aA-sd.a.z.0-9.ABOYZ"};
+
+  for (auto &userdata : bad_userdatas) {
+    for (auto &domain : bad_domains) {
+      check_is_email_address(userdata + '@' + domain, false);
+      check_is_email_address(userdata + domain, false);
+    }
+    for (auto &domain : good_domains) {
+      check_is_email_address(userdata + '@' + domain, false);
+      check_is_email_address(userdata + domain, false);
+    }
+  }
+  for (auto &userdata : good_userdatas) {
+    for (auto &domain : bad_domains) {
+      check_is_email_address(userdata + '@' + domain, false);
+      check_is_email_address(userdata + domain, false);
+    }
+    for (auto &domain : good_domains) {
+      check_is_email_address(userdata + '@' + domain, true);
+      check_is_email_address(userdata + domain, false);
+    }
+  }
+}
+
+static void check_url(string str, std::vector<string> expected_urls,
+                      std::vector<string> expected_email_addresses = {}) {
+  auto result_slice = find_urls(str);
+  std::vector<string> result_urls;
+  std::vector<string> result_email_addresses;
+  for (auto &it : result_slice) {
+    if (!it.second) {
+      result_urls.push_back(it.first.str());
+    } else {
+      result_email_addresses.push_back(it.first.str());
+    }
+  }
+  if (result_urls != expected_urls) {
+    LOG(FATAL) << tag("text", str) << tag("got", format::as_array(result_urls))
+               << tag("expected", format::as_array(expected_urls));
+  }
+  if (result_email_addresses != expected_email_addresses) {
+    LOG(FATAL) << tag("text", str) << tag("got", format::as_array(result_email_addresses))
+               << tag("expected", format::as_array(expected_email_addresses));
+  }
+}
+
+TEST(MessageEntities, url) {
+  check_url("telegram.org", {"telegram.org"});
+  check_url("(telegram.org)", {"telegram.org"});
+  check_url("\ntelegram.org)", {"telegram.org"});
+  check_url(" telegram.org)", {"telegram.org"});
+  check_url(".telegram.org)", {});
+  check_url("()telegram.org/?q=()", {"telegram.org/?q=()"});
+  check_url("\"telegram.org\"", {"telegram.org"});
+  check_url(" telegram. org. www. com... telegram.org... ...google.com...", {"telegram.org"});
+  check_url(" telegram.org ", {"telegram.org"});
+  check_url("Такой сайт: http://www.google.com или такой telegram.org ", {"http://www.google.com", "telegram.org"});
+  check_url(" telegram.org. ", {"telegram.org"});
+  check_url("http://google,.com", {});
+  check_url("http://telegram.org/?asd=123#123.", {"http://telegram.org/?asd=123#123"});
+  check_url("[http://google.com](test)", {"http://google.com"});
+  check_url("", {});
+  check_url(".", {});
+  check_url("http://@google.com", {});
+  check_url("http://@goog.com", {});  // TODO: server fix
+  check_url("http://@@google.com", {"http://@@google.com"});
+  check_url("http://a@google.com", {"http://a@google.com"});
+  check_url("http://test@google.com", {"http://test@google.com"});
+  check_url("google.com:᪉᪉᪉᪉᪉", {"google.com"});
+  check_url("https://telegram.org", {"https://telegram.org"});
+  check_url("http://telegram.org", {"http://telegram.org"});
+  check_url("ftp://telegram.org", {"ftp://telegram.org"});
+  check_url("ftps://telegram.org", {});
+  check_url("sftp://telegram.org", {"sftp://telegram.org"});
+  check_url("hTtPs://telegram.org", {"hTtPs://telegram.org"});
+  check_url("HTTP://telegram.org", {"HTTP://telegram.org"});
+  check_url("аHTTP://telegram.org", {"HTTP://telegram.org"});
+  check_url("sHTTP://telegram.org", {});
+  check_url("://telegram.org", {});
+  check_url("google.com:᪀᪀", {"google.com"});
+  check_url(
+      "http://"
+      "abcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkab"
+      "cdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcd"
+      "efghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdef"
+      "ghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefgh"
+      "ijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghij"
+      "kabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijka"
+      "bcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabc"
+      "defghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijkabcdefghijk.com",
+      {});
+  check_url("http://  .com", {});
+  check_url("URL:     .com", {});
+  check_url("URL: .com", {});
+  check_url(".com", {});
+  check_url("http://  .", {});
+  check_url("http://.", {});
+  check_url("http://.com", {});
+  check_url("http://  .", {});
+  check_url(",ahttp://google.com", {"http://google.com"});
+  check_url(".ahttp://google.com", {});
+  check_url("http://1.0", {});
+  check_url("http://a.0", {});
+  check_url("http://a.a", {});
+  check_url("google.com:1#ab c", {"google.com:1#ab"});
+  check_url("google.com:1#", {"google.com:1#"});
+  check_url("google.com:1#1", {"google.com:1#1"});
+  check_url("google.com:00000001/abs", {"google.com:00000001/abs"});
+  check_url("google.com:000000065535/abs", {"google.com:000000065535/abs"});
+  check_url("google.com:000000065536/abs", {"google.com"});
+  check_url("google.com:000000080/abs", {"google.com:000000080/abs"});
+  check_url("google.com:0000000/abs", {"google.com"});
+  check_url("google.com:0/abs", {"google.com"});
+  check_url("google.com:/abs", {"google.com"});
+  check_url("google.com:65535", {"google.com:65535"});
+  check_url("google.com:65536", {"google.com"});
+  check_url("google.com:99999", {"google.com"});
+  check_url("google.com:100000", {"google.com"});
+  check_url("127.001", {});
+  check_url("127.0.0.1", {"127.0.0.1"});
+  check_url("127.0.0.01", {});
+  check_url("127.0.0.256", {});
+  check_url("127.0.0.300", {});
+  check_url("127.0.0.1000", {});
+  check_url("127.0.0.260", {});
+  check_url("1.0", {});
+  check_url("www.🤙.tk", {"www.🤙.tk"});
+  check_url("a.ab", {});
+  check_url("test.abd", {});
+  check_url("ТеСт.Москва", {});
+  check_url("ТеСт.МоСкВΑ", {});
+  check_url("ТеСт.МоСкВа", {"ТеСт.МоСкВа"});
+  check_url("ТеСт.МоСкВач", {});
+  check_url("http://ÀТеСт.МоСкВач", {"http://ÀТеСт.МоСкВач"});
+  check_url("ÀÁ.com. ÀÁ.com.", {"ÀÁ.com", "ÀÁ.com"});
+  check_url("ÀÁ.com,ÀÁ.com.", {"ÀÁ.com", "ÀÁ.com"});
+  check_url("teiegram.org", {});
+  check_url("http://test.google.com/?q=abc()}[]def", {"http://test.google.com/?q=abc()"});
+  check_url("http://test.google.com/?q=abc([{)]}def", {"http://test.google.com/?q=abc([{)]}def"});
+  check_url("http://test.google.com/?q=abc(){}]def", {"http://test.google.com/?q=abc(){}"});
+  check_url("http://test.google.com/?q=abc){}[]def", {"http://test.google.com/?q=abc"});
+  check_url("http://test.google.com/?q=abc(){}[]def", {"http://test.google.com/?q=abc(){}[]def"});
+  check_url("http://test-.google.com", {});
+  check_url("http://test_.google.com", {"http://test_.google.com"});
+  check_url("http://google_.com", {});
+  check_url("http://google._com_", {});
+  check_url("http://[2001:4860:0:2001::68]/", {});  // TODO
+  check_url("test.abd", {});
+  check_url("/.b/..a    @.....@/. a.ba", {"a.ba"});
+  check_url("bbbbbbbbbbbbbb.@.@", {});
+  check_url("http://google.com/", {"http://google.com/"});
+  check_url("http://google.com?", {"http://google.com"});
+  check_url("http://google.com#", {"http://google.com#"});
+  check_url("http://google.com/?", {"http://google.com/"});
+  check_url("https://www.google.com/ab,", {"https://www.google.com/ab"});
+  check_url("@.", {});
+  check_url(
+      "a.b.google.com dfsknnfs gsdfgsg http://códuia.de/ dffdg,\" 12)(cpia.de/())(\" http://гришка.рф/ sdufhdf "
+      "http://xn--80afpi2a3c.xn--p1ai/ I have a good time.Thanks, guys!\n\n(hdfughidufhgdis)go#ogle.com гришка.рф "
+      "hsighsdf gi почта.рф\n\n✪df.ws/123      "
+      "xn--80afpi2a3c.xn--p1ai\n\nhttp://foo.com/blah_blah\nhttp://foo.com/blah_blah/\n(Something like "
+      "http://foo.com/blah_blah)\nhttp://foo.com/blah_blah_(wikipedi8989a_Вася)\n(Something like "
+      "http://foo.com/blah_blah_(Стакан_007))\nhttp://foo.com/blah_blah.\nhttp://foo.com/blah_blah/.\n<http://foo.com/"
+      "blah_blah>\n<http://fo@@@@@@@@@^%#*@^&@$#*@#%^*&!^#o.com/blah_blah/>\nhttp://foo.com/blah_blah,\nhttp://"
+      "www.example.com/wpstyle/?p=364.\nhttp://✪df.ws/123\nrdar://1234\nrdar:/1234\nhttp://"
+      "userid:password@example.com:8080\nhttp://userid@example.com\nhttp://userid@example.com:8080\nhttp://"
+      "userid:password@example.com\nhttp://example.com:8080 "
+      "x-yojimbo-item://6303E4C1-xxxx-45A6-AB9D-3A908F59AE0E\nmessage://"
+      "%3c330e7f8409726r6a4ba78dkf1fd71420c1bf6ff@mail.gmail.com%3e\nhttp://➡️.ws/䨹\nwww.➡️.ws/"
+      "䨹\n<tag>http://example.com</tag>\nJust a www.example.com "
+      "link.\n\n➡️.ws/"
+      "䨹\n\nabcdefghijklmnopqrstuvwxyz0123456789qwe_sdfsdf.aweawe-sdfs.com\nwww.🤙.tk:1\ngoogle.com:"
+      "᪉᪉᪉᪉\ngoogle."
+      "com:᪀᪀\nhttp://  .com\nURL:     .com\nURL: "
+      ".com\n\ngoogle.com?qwe\ngoogle.com#qwe\ngoogle.com/?\ngoogle.com/#\ngoogle.com?\ngoogle.com#\n",
+      {"a.b.google.com",
+       "http://códuia.de/",
+       "cpia.de/()",
+       "http://гришка.рф/",
+       "http://xn--80afpi2a3c.xn--p1ai/",
+       "гришка.рф",
+       "почта.рф",
+       "✪df.ws/123",
+       "xn--80afpi2a3c.xn--p1ai",
+       "http://foo.com/blah_blah",
+       "http://foo.com/blah_blah/",
+       "http://foo.com/blah_blah",
+       "http://foo.com/blah_blah_(wikipedi8989a_Вася)",
+       "http://foo.com/blah_blah_(Стакан_007)",
+       "http://foo.com/blah_blah",
+       "http://foo.com/blah_blah/",
+       "http://foo.com/blah_blah",
+       "http://foo.com/blah_blah",
+       "http://www.example.com/wpstyle/?p=364",
+       "http://✪df.ws/123",
+       "http://userid:password@example.com:8080",
+       "http://userid@example.com",
+       "http://userid@example.com:8080",
+       "http://userid:password@example.com",
+       "http://example.com:8080",
+       "http://➡️.ws/䨹",
+       "www.➡️.ws/䨹",
+       "http://example.com",
+       "www.example.com",
+       "➡️.ws/䨹",
+       "abcdefghijklmnopqrstuvwxyz0123456789qwe_sdfsdf.aweawe-sdfs.com",
+       "www.🤙.tk:1",
+       "google.com",
+       "google.com",
+       "google.com?qwe",
+       "google.com#qwe",
+       "google.com/",
+       "google.com/#",
+       "google.com",
+       "google.com#"});
+  check_url("https://t.…", {});
+  check_url("('http://telegram.org/a-b/?br=ie&lang=en',)", {"http://telegram.org/a-b/?br=ie&lang=en"});
+  check_url("https://ai.telegram.org/bot%20bot/test-...", {"https://ai.telegram.org/bot%20bot/test-"});
+  check_url("a.bc@c.com", {}, {"a.bc@c.com"});
+  check_url("https://a.bc@c.com", {"https://a.bc@c.com"});
+  check_url("https://a.de[bc@c.com", {"https://a.de"}, {"bc@c.com"});
+  check_url("https://a.de/bc@c.com", {"https://a.de/bc@c.com"});
+  check_url("https://a.de]bc@c.com", {"https://a.de"}, {"bc@c.com"});
+  check_url("https://a.de{bc@c.com", {"https://a.de"}, {"bc@c.com"});
+  check_url("https://a.de}bc@c.com", {"https://a.de"}, {"bc@c.com"});
+  check_url("https://a.de(bc@c.com", {"https://a.de"}, {"bc@c.com"});
+  check_url("https://a.de)bc@c.com", {"https://a.de"}, {"bc@c.com"});
+  check_url("https://a.de\\bc@c.com", {"https://a.de\\bc@c.com"});
+  check_url("https://a.de'bc@c.com", {"https://a.de"}, {"bc@c.com"});
+  check_url("https://a.de`bc@c.com", {"https://a.de"}, {"bc@c.com"});
+  check_url("https://a.bc:de.fg@c.com", {"https://a.bc:de.fg@c.com"});
+  check_url("https://a:h.bc:de.fg@c.com", {"https://a:h.bc:de.fg@c.com"});
+  check_url("https://abc@c.com", {"https://abc@c.com"});
+  check_url("https://de[bc@c.com", {}, {"bc@c.com"});
+  check_url("https://de/bc@c.com", {});
+  check_url("https://de]bc@c.com", {}, {"bc@c.com"});
+  check_url("https://de{bc@c.com", {}, {"bc@c.com"});
+  check_url("https://de}bc@c.com", {}, {"bc@c.com"});
+  check_url("https://de(bc@c.com", {}, {"bc@c.com"});
+  check_url("https://de)bc@c.com", {}, {"bc@c.com"});
+  check_url("https://de\\bc@c.com", {"https://de\\bc@c.com"});
+  check_url("https://de'bc@c.com", {}, {"bc@c.com"});
+  check_url("https://de`bc@c.com", {}, {"bc@c.com"});
+  check_url("https://bc:defg@c.com", {"https://bc:defg@c.com"});
+  check_url("https://a:hbc:defg@c.com", {"https://a:hbc:defg@c.com"});
+  check_url("https://a.bc@test.com:cd.com", {"https://a.bc@test.com", "cd.com"});
+  check_url("telegram.Org", {});
+  check_url("telegram.ORG", {"telegram.ORG"});
+  check_url("a.b.c.com.a.b.c", {});
+  check_url("File '/usr/views.py'", {});  // TODO server fix
+  check_url("@views.py'", {});            // TODO server fix
+  check_url("#views.py'", {});            // TODO server fix
+  check_url("/views.py'", {});            // TODO server fix
+  check_url(".views.py", {});
+  check_url("'views.py'", {"views.py"});
+  check_url("bug.http://test.com/test/+#", {});  // TODO {"http://test.com/test/+#"}
+  check_url("//AB.C.D.E.F.GH//", {});
+  check_url("<http://www.ics.uci.edu/pub/ietf/uri/historical.html#WARNING>",
+            {"http://www.ics.uci.edu/pub/ietf/uri/historical.html#WARNING"});
+  check_url("Look :test@example.com", {":test@example.com"}, {});  // TODO {}, {"test@example.com"}
+  check_url("http://test.com#a", {"http://test.com#a"});
+  check_url("http://test.com#", {"http://test.com#"});
+  check_url("http://test.com?#", {"http://test.com?#"});
+  check_url("http://test.com/?#", {"http://test.com/?#"});
+  check_url("https://t.me/abcdef…", {"https://t.me/abcdef"});
+  check_url("https://t.me…", {"https://t.me"});
+  check_url("https://t.m…", {});
+  check_url("https://t.…", {});
+  check_url("https://t…", {});
+  check_url("👉http://ab.com/cdefgh-1IJ", {"http://ab.com/cdefgh-1IJ"});
+  check_url("...👉http://ab.com/cdefgh-1IJ", {});  // TODO
+}
diff --git a/libs/tdlib/td/test/mtproto.cpp b/libs/tdlib/td/test/mtproto.cpp
new file mode 100644
index 0000000000..7702a1e37b
--- /dev/null
+++ b/libs/tdlib/td/test/mtproto.cpp
@@ -0,0 +1,347 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/tests.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
+#include "td/mtproto/crypto.h"
+#include "td/mtproto/Handshake.h"
+#include "td/mtproto/HandshakeActor.h"
+#include "td/mtproto/HandshakeConnection.h"
+#include "td/mtproto/PingConnection.h"
+#include "td/mtproto/RawConnection.h"
+
+#include "td/net/Socks5.h"
+
+#include "td/telegram/ConfigManager.h"
+#include "td/telegram/net/PublicRsaKeyShared.h"
+
+#include "td/utils/logging.h"
+#include "td/utils/port/IPAddress.h"
+#include "td/utils/port/SocketFd.h"
+#include "td/utils/Status.h"
+
+REGISTER_TESTS(mtproto);
+
+using namespace td;
+using namespace mtproto;
+
+#if !TD_WINDOWS && !TD_EMSCRIPTEN  // TODO
+TEST(Mtproto, config) {
+  ConcurrentScheduler sched;
+  int threads_n = 0;
+  sched.init(threads_n);
+
+  int cnt = 3;
+  {
+    auto guard = sched.get_current_guard();
+    get_simple_config_azure(PromiseCreator::lambda([&](Result<SimpleConfig> r_simple_config) {
+      LOG(ERROR) << to_string(r_simple_config.ok());
+      if (--cnt == 0) {
+        Scheduler::instance()->finish();
+      }
+    }))
+        .release();
+
+    get_simple_config_google_app(PromiseCreator::lambda([&](Result<SimpleConfig> r_simple_config) {
+      LOG(ERROR) << to_string(r_simple_config.ok());
+      if (--cnt == 0) {
+        Scheduler::instance()->finish();
+      }
+    }))
+        .release();
+
+    get_simple_config_google_dns(PromiseCreator::lambda([&](Result<SimpleConfig> r_simple_config) {
+      LOG(ERROR) << to_string(r_simple_config.ok());
+      if (--cnt == 0) {
+        Scheduler::instance()->finish();
+      }
+    }))
+        .release();
+  }
+  sched.start();
+  while (sched.run_main(10)) {
+    // empty;
+  }
+  sched.finish();
+}
+#endif
+
+TEST(Mtproto, encrypted_config) {
+  string data =
+      "   LQ2 \b\n\tru6xVXpHHckW4eQWK0X3uThupVOor5sXT8t298IjDksYeUseQTOIrnUqiQj7o"
+      "+ZgPfhnfe+lfcQA+naax9akgllimjlJtL5riTf3O7iqZSnJ614qmCucxqqVTbXk/"
+      "hY2KaJTtsMqk7cShJjM3aQ4DD40h2InTaG7uyVO2q7K0GMUTeY3AM0Rt1lUjKHLD"
+      "g4RwjTzZaG8TwfgL/mZ7jsvgTTTATPWKUo7SmxQ9Hsj+07NMGqr6JKZS6aiU1Knz"
+      "VGCZ3OJEyRYocktN4HjaLpkguilaHWlVM2UNFUd5a+ajfLIiiKlH0FRC3XZ12CND"
+      "Y+NBjv0I57N2O4fBfswTlA==  ";
+  auto config = decode_config(data).move_as_ok();
+}
+
+class TestPingActor : public Actor {
+ public:
+  TestPingActor(IPAddress ip_address, Status *result) : ip_address_(ip_address), result_(result) {
+  }
+
+ private:
+  IPAddress ip_address_;
+  std::unique_ptr<mtproto::PingConnection> ping_connection_;
+  Status *result_;
+
+  void start_up() override {
+    ping_connection_ = std::make_unique<mtproto::PingConnection>(std::make_unique<mtproto::RawConnection>(
+        SocketFd::open(ip_address_).move_as_ok(), mtproto::TransportType::Tcp, nullptr));
+
+    ping_connection_->get_pollable().set_observer(this);
+    subscribe(ping_connection_->get_pollable());
+    set_timeout_in(10);
+    yield();
+  }
+  void tear_down() override {
+    unsubscribe_before_close(ping_connection_->get_pollable());
+    ping_connection_->close();
+    Scheduler::instance()->finish();
+  }
+
+  void loop() override {
+    auto status = ping_connection_->flush();
+    if (status.is_error()) {
+      *result_ = std::move(status);
+      return stop();
+    }
+    if (ping_connection_->was_pong()) {
+      LOG(ERROR) << "GOT PONG";
+      return stop();
+    }
+  }
+
+  void timeout_expired() override {
+    *result_ = Status::Error("Timeout expired");
+    stop();
+  }
+};
+
+static IPAddress get_default_ip_address() {
+  IPAddress ip_address;
+  ip_address.init_ipv4_port("149.154.167.40", 80).ensure();
+  return ip_address;
+}
+
+class Mtproto_ping : public td::Test {
+ public:
+  using Test::Test;
+  bool step() final {
+    if (!is_inited_) {
+      sched_.init(0);
+      sched_.create_actor_unsafe<TestPingActor>(0, "Pinger", get_default_ip_address(), &result_).release();
+      sched_.start();
+      is_inited_ = true;
+    }
+
+    bool ret = sched_.run_main(10);
+    if (ret) {
+      return true;
+    }
+    sched_.finish();
+    if (result_.is_error()) {
+      LOG(ERROR) << result_;
+    }
+    ASSERT_TRUE(result_.is_ok());
+    return false;
+  }
+
+ private:
+  bool is_inited_ = false;
+  ConcurrentScheduler sched_;
+  Status result_;
+};
+Mtproto_ping mtproto_ping("Mtproto_ping");
+
+class Context : public AuthKeyHandshakeContext {
+ public:
+  DhCallback *get_dh_callback() override {
+    return nullptr;
+  }
+  PublicRsaKeyInterface *get_public_rsa_key_interface() override {
+    return &public_rsa_key;
+  }
+
+ private:
+  PublicRsaKeyShared public_rsa_key{DcId::empty()};
+};
+
+class HandshakeTestActor : public Actor {
+ public:
+  explicit HandshakeTestActor(Status *result) : result_(result) {
+  }
+
+ private:
+  Status *result_;
+  bool wait_for_raw_connection_ = false;
+  std::unique_ptr<RawConnection> raw_connection_;
+  bool wait_for_handshake_ = false;
+  std::unique_ptr<AuthKeyHandshake> handshake_;
+  Status status_;
+  bool wait_for_result_ = false;
+
+  void tear_down() override {
+    if (raw_connection_) {
+      raw_connection_->close();
+    }
+    finish(Status::Error("Interrupted"));
+  }
+  void loop() override {
+    if (!wait_for_raw_connection_ && !raw_connection_) {
+      raw_connection_ = std::make_unique<mtproto::RawConnection>(SocketFd::open(get_default_ip_address()).move_as_ok(),
+                                                                 mtproto::TransportType::Tcp, nullptr);
+    }
+    if (!wait_for_handshake_ && !handshake_) {
+      handshake_ = std::make_unique<AuthKeyHandshake>(0);
+    }
+    if (raw_connection_ && handshake_) {
+      if (wait_for_result_) {
+        wait_for_result_ = false;
+        if (status_.is_error()) {
+          finish(std::move(status_));
+          return stop();
+        }
+        if (!handshake_->is_ready_for_finish()) {
+          finish(Status::Error("Key is not ready.."));
+          return stop();
+        }
+        finish(Status::OK());
+        return stop();
+      }
+
+      wait_for_result_ = true;
+      create_actor<HandshakeActor>(
+          "HandshakeActor", std::move(handshake_), std::move(raw_connection_), std::make_unique<Context>(), 10.0,
+          PromiseCreator::lambda([self = actor_id(this)](Result<std::unique_ptr<RawConnection>> raw_connection) {
+            send_closure(self, &HandshakeTestActor::got_connection, std::move(raw_connection), 1);
+          }),
+          PromiseCreator::lambda([self = actor_id(this)](Result<std::unique_ptr<AuthKeyHandshake>> handshake) {
+            send_closure(self, &HandshakeTestActor::got_handshake, std::move(handshake), 1);
+          }))
+          .release();
+      wait_for_raw_connection_ = true;
+      wait_for_handshake_ = true;
+    }
+  }
+
+  void got_connection(Result<std::unique_ptr<RawConnection>> r_raw_connection, int32 dummy) {
+    CHECK(wait_for_raw_connection_);
+    wait_for_raw_connection_ = false;
+    if (r_raw_connection.is_ok()) {
+      raw_connection_ = r_raw_connection.move_as_ok();
+      status_ = Status::OK();
+    } else {
+      status_ = r_raw_connection.move_as_error();
+    }
+    // TODO: save error
+    loop();
+  }
+
+  void got_handshake(Result<std::unique_ptr<AuthKeyHandshake>> r_handshake, int32 dummy) {
+    CHECK(wait_for_handshake_);
+    wait_for_handshake_ = false;
+    CHECK(r_handshake.is_ok());
+    handshake_ = r_handshake.move_as_ok();
+    loop();
+  }
+
+  void finish(Status status) {
+    if (!result_) {
+      return;
+    }
+    *result_ = std::move(status);
+    result_ = nullptr;
+    Scheduler::instance()->finish();
+  }
+};
+
+class Mtproto_handshake : public td::Test {
+ public:
+  using Test::Test;
+  bool step() final {
+    if (!is_inited_) {
+      sched_.init(0);
+      sched_.create_actor_unsafe<HandshakeTestActor>(0, "HandshakeTestActor", &result_).release();
+      sched_.start();
+      is_inited_ = true;
+    }
+
+    bool ret = sched_.run_main(10);
+    if (ret) {
+      return true;
+    }
+    sched_.finish();
+    if (result_.is_error()) {
+      LOG(ERROR) << result_;
+    }
+    ASSERT_TRUE(result_.is_ok());
+    return false;
+  }
+
+ private:
+  bool is_inited_ = false;
+  ConcurrentScheduler sched_;
+  Status result_;
+};
+Mtproto_handshake mtproto_handshake("Mtproto_handshake");
+
+class Socks5TestActor : public Actor {
+ public:
+  void start_up() override {
+    auto promise = PromiseCreator::lambda([actor_id = actor_id(this)](Result<SocketFd> res) {
+      send_closure(actor_id, &Socks5TestActor::on_result, std::move(res), false);
+    });
+
+    class Callback : public Socks5::Callback {
+     public:
+      explicit Callback(Promise<SocketFd> promise) : promise_(std::move(promise)) {
+      }
+      void set_result(Result<SocketFd> result) override {
+        promise_.set_result(std::move(result));
+      }
+      void on_connected() override {
+      }
+
+     private:
+      Promise<SocketFd> promise_;
+    };
+
+    IPAddress socks5_ip;
+    socks5_ip.init_ipv4_port("131.191.89.104", 43077).ensure();
+    IPAddress mtproto_ip = get_default_ip_address();
+
+    auto r_socket = SocketFd::open(socks5_ip);
+    create_actor<Socks5>("socks5", r_socket.move_as_ok(), mtproto_ip, "", "",
+                         std::make_unique<Callback>(std::move(promise)), actor_shared())
+        .release();
+  }
+
+ private:
+  void on_result(Result<SocketFd> res, bool dummy) {
+    res.ensure();
+    Scheduler::instance()->finish();
+  }
+};
+
+TEST(Mtproto, socks5) {
+  return;
+  ConcurrentScheduler sched;
+  int threads_n = 0;
+  sched.init(threads_n);
+
+  sched.create_actor_unsafe<Socks5TestActor>(0, "Socks5TestActor").release();
+  sched.start();
+  while (sched.run_main(10)) {
+    // empty;
+  }
+  sched.finish();
+}
diff --git a/libs/tdlib/td/test/secret.cpp b/libs/tdlib/td/test/secret.cpp
new file mode 100644
index 0000000000..2abed9787b
--- /dev/null
+++ b/libs/tdlib/td/test/secret.cpp
@@ -0,0 +1,1056 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/actor/PromiseFuture.h"
+
+#include "td/db/binlog/detail/BinlogEventsProcessor.h"
+
+#include "td/mtproto/crypto.h"
+#include "td/mtproto/utils.h"
+
+#include "td/telegram/Global.h"
+#include "td/telegram/MessageId.h"
+#include "td/telegram/SecretChatActor.h"
+#include "td/telegram/SecretChatId.h"
+
+#include "td/telegram/secret_api.h"
+#include "td/telegram/telegram_api.h"
+
+#include "td/tl/tl_object_parse.h"
+#include "td/tl/tl_object_store.h"
+
+#include "td/utils/base64.h"
+#include "td/utils/buffer.h"
+#include "td/utils/crypto.h"
+#include "td/utils/format.h"
+#include "td/utils/Gzip.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/Random.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/tests.h"
+#include "td/utils/tl_helpers.h"
+#include "td/utils/tl_parsers.h"
+#include "td/utils/tl_storers.h"
+
+#include <cstdio>
+#include <ctime>
+#include <limits>
+#include <map>
+#include <memory>
+
+REGISTER_TESTS(secret);
+
+namespace my_api {
+
+using namespace td;
+
+//messages_getDhConfig
+class messages_getDhConfig {
+ public:
+  int32 version_;
+  int32 random_length_;
+
+  messages_getDhConfig() = default;
+
+  messages_getDhConfig(int32 version_, int32 random_length_);
+
+  static const int32 ID = 651135312;
+
+  explicit messages_getDhConfig(TlBufferParser &p)
+#define FAIL(error) p.set_error(error)
+      : version_(TlFetchInt::parse(p))
+      , random_length_(TlFetchInt::parse(p))
+#undef FAIL
+  {
+  }
+};
+
+//InputUser
+class InputUser {
+ public:
+  static tl_object_ptr<InputUser> fetch(TlBufferParser &p);
+};
+
+class inputUser final : public InputUser {
+ public:
+  int32 user_id_;
+  int64 access_hash_;
+
+  static const int32 ID = -668391402;
+  inputUser() = default;
+
+  explicit inputUser(TlBufferParser &p)
+#define FAIL(error) p.set_error(error)
+      : user_id_(TlFetchInt::parse(p))
+      , access_hash_(TlFetchLong::parse(p))
+#undef FAIL
+  {
+  }
+};
+tl_object_ptr<InputUser> InputUser::fetch(TlBufferParser &p) {
+#define FAIL(error)   \
+  p.set_error(error); \
+  return nullptr;
+  int constructor = p.fetch_int();
+  switch (constructor) {
+    case inputUser::ID:
+      return make_tl_object<inputUser>(p);
+    default:
+      FAIL(PSTRING() << "Unknown constructor found " << format::as_hex(constructor));
+  }
+#undef FAIL
+}
+
+class messages_requestEncryption final {
+ public:
+  tl_object_ptr<InputUser> user_id_;
+  int32 random_id_;
+  BufferSlice g_a_;
+
+  static const int32 ID = -162681021;
+  messages_requestEncryption();
+
+  explicit messages_requestEncryption(TlBufferParser &p)
+#define FAIL(error) p.set_error(error)
+      : user_id_(TlFetchObject<InputUser>::parse(p))
+      , random_id_(TlFetchInt::parse(p))
+      , g_a_(TlFetchBytes<BufferSlice>::parse(p))
+#undef FAIL
+  {
+  }
+};
+
+class inputEncryptedChat final {
+ public:
+  int32 chat_id_;
+  int64 access_hash_;
+
+  inputEncryptedChat() = default;
+
+  static const int32 ID = -247351839;
+  explicit inputEncryptedChat(TlBufferParser &p)
+#define FAIL(error) p.set_error(error)
+      : chat_id_(TlFetchInt::parse(p))
+      , access_hash_(TlFetchLong::parse(p))
+#undef FAIL
+  {
+  }
+  static tl_object_ptr<inputEncryptedChat> fetch(TlBufferParser &p) {
+    return make_tl_object<inputEncryptedChat>(p);
+  }
+};
+
+class messages_acceptEncryption final {
+ public:
+  tl_object_ptr<inputEncryptedChat> peer_;
+  BufferSlice g_b_;
+  int64 key_fingerprint_;
+
+  messages_acceptEncryption() = default;
+
+  static const int32 ID = 1035731989;
+
+  explicit messages_acceptEncryption(TlBufferParser &p)
+#define FAIL(error) p.set_error(error)
+      : peer_(TlFetchBoxed<TlFetchObject<inputEncryptedChat>, -247351839>::parse(p))
+      , g_b_(TlFetchBytes<BufferSlice>::parse(p))
+      , key_fingerprint_(TlFetchLong::parse(p))
+#undef FAIL
+  {
+  }
+};
+
+class messages_sendEncryptedService final {
+ public:
+  tl_object_ptr<inputEncryptedChat> peer_;
+  int64 random_id_;
+  BufferSlice data_;
+
+  messages_sendEncryptedService() = default;
+  static const int32 ID = 852769188;
+  explicit messages_sendEncryptedService(TlBufferParser &p)
+#define FAIL(error) p.set_error(error)
+      : peer_(TlFetchBoxed<TlFetchObject<inputEncryptedChat>, -247351839>::parse(p))
+      , random_id_(TlFetchLong::parse(p))
+      , data_(TlFetchBytes<BufferSlice>::parse(p))
+#undef FAIL
+  {
+  }
+};
+
+class messages_sendEncrypted final {
+ public:
+  tl_object_ptr<inputEncryptedChat> peer_;
+  int64 random_id_;
+  BufferSlice data_;
+
+  messages_sendEncrypted() = default;
+  static const int32 ID = -1451792525;
+
+  explicit messages_sendEncrypted(TlBufferParser &p)
+#define FAIL(error) p.set_error(error)
+      : peer_(TlFetchBoxed<TlFetchObject<inputEncryptedChat>, -247351839>::parse(p))
+      , random_id_(TlFetchLong::parse(p))
+      , data_(TlFetchBytes<BufferSlice>::parse(p))
+#undef FAIL
+  {
+  }
+};
+
+template <class F>
+static void downcast_call(TlBufferParser &p, F &&f) {
+  auto id = p.fetch_int();
+  switch (id) {
+    case messages_getDhConfig::ID:
+      return f(*make_tl_object<messages_getDhConfig>(p));
+    case messages_requestEncryption::ID:
+      return f(*make_tl_object<messages_requestEncryption>(p));
+    case messages_acceptEncryption::ID:
+      return f(*make_tl_object<messages_acceptEncryption>(p));
+    case messages_sendEncrypted::ID:
+      return f(*make_tl_object<messages_sendEncrypted>(p));
+    case messages_sendEncryptedService::ID:
+      return f(*make_tl_object<messages_sendEncryptedService>(p));
+    default:
+      CHECK(0) << id;
+      UNREACHABLE();
+  }
+}
+
+class messages_dhConfig final {
+ public:
+  int32 g_;
+  BufferSlice p_;
+  int32 version_;
+  BufferSlice random_;
+
+  messages_dhConfig() = default;
+
+  messages_dhConfig(int32 g_, BufferSlice &&p_, int32 version_, BufferSlice &&random_)
+      : g_(g_), p_(std::move(p_)), version_(version_), random_(std::move(random_)) {
+  }
+
+  static const int32 ID = 740433629;
+  int32 get_id() const {
+    return ID;
+  }
+
+  void store(TlStorerCalcLength &s) const {
+    (void)sizeof(s);
+    TlStoreBinary::store(g_, s);
+    TlStoreString::store(p_, s);
+    TlStoreBinary::store(version_, s);
+    TlStoreString::store(random_, s);
+  }
+  void store(TlStorerUnsafe &s) const {
+    (void)sizeof(s);
+    TlStoreBinary::store(g_, s);
+    TlStoreString::store(p_, s);
+    TlStoreBinary::store(version_, s);
+    TlStoreString::store(random_, s);
+  }
+};
+
+class encryptedChat final {
+ public:
+  int32 id_;
+  int64 access_hash_;
+  int32 date_;
+  int32 admin_id_;
+  int32 participant_id_;
+  BufferSlice g_a_or_b_;
+  int64 key_fingerprint_;
+
+  encryptedChat() = default;
+
+  encryptedChat(int32 id_, int64 access_hash_, int32 date_, int32 admin_id_, int32 participant_id_,
+                BufferSlice &&g_a_or_b_, int64 key_fingerprint_)
+      : id_(id_)
+      , access_hash_(access_hash_)
+      , date_(date_)
+      , admin_id_(admin_id_)
+      , participant_id_(participant_id_)
+      , g_a_or_b_(std::move(g_a_or_b_))
+      , key_fingerprint_(key_fingerprint_) {
+  }
+
+  static const int32 ID = -94974410;
+  int32 get_id() const {
+    return ID;
+  }
+
+  void store(TlStorerCalcLength &s) const {
+    (void)sizeof(s);
+    TlStoreBinary::store(id_, s);
+    TlStoreBinary::store(access_hash_, s);
+    TlStoreBinary::store(date_, s);
+    TlStoreBinary::store(admin_id_, s);
+    TlStoreBinary::store(participant_id_, s);
+    TlStoreString::store(g_a_or_b_, s);
+    TlStoreBinary::store(key_fingerprint_, s);
+  }
+
+  void store(TlStorerUnsafe &s) const {
+    (void)sizeof(s);
+    TlStoreBinary::store(id_, s);
+    TlStoreBinary::store(access_hash_, s);
+    TlStoreBinary::store(date_, s);
+    TlStoreBinary::store(admin_id_, s);
+    TlStoreBinary::store(participant_id_, s);
+    TlStoreString::store(g_a_or_b_, s);
+    TlStoreBinary::store(key_fingerprint_, s);
+  }
+};
+
+class messages_sentEncryptedMessage final {
+ public:
+  int32 date_;
+
+  messages_sentEncryptedMessage() = default;
+
+  explicit messages_sentEncryptedMessage(int32 date_) : date_(date_) {
+  }
+
+  static const int32 ID = 1443858741;
+  int32 get_id() const {
+    return ID;
+  }
+
+  void store(TlStorerCalcLength &s) const {
+    (void)sizeof(s);
+    TlStoreBinary::store(date_, s);
+  }
+
+  void store(TlStorerUnsafe &s) const {
+    (void)sizeof(s);
+    TlStoreBinary::store(date_, s);
+  }
+};
+
+}  // namespace my_api
+
+namespace td {
+static int32 g = 3;
+static string prime_base64 =
+    "xxyuucaxyQSObFIvcPE_c5gNQCOOPiHBSTTQN1Y9kw9IGYoKp8FAWCKUk9IlMPTb-jNvbgrJJROVQ67UTM58NyD9UfaUWHBaxozU_mtrE6vcl0ZRKW"
+    "kyhFTxj6-MWV9kJHf-lrsqlB1bzR1KyMxJiAcI-ps3jjxPOpBgvuZ8-aSkppWBEFGQfhYnU7VrD2tBDbp02KhLKhSzFE4O8ShHVP0X7ZUNWWW0ud1G"
+    "WC2xF40WnGvEZbDW_5yjko_vW5rk5Bj8Feg-vqD4f6n_Xu1wBQ3tKEn0e_lZ2VaFDOkphR8NgRX2NbEF7i5OFdBLJFS_b0-t8DSxBAMRnNjjuS_MW"
+    "w";
+
+class FakeDhCallback : public DhCallback {
+ public:
+  int is_good_prime(Slice prime_str) const override {
+    auto it = cache.find(prime_str.str());
+    if (it == cache.end()) {
+      return -1;
+    }
+    return it->second;
+  }
+  void add_good_prime(Slice prime_str) const override {
+    cache[prime_str.str()] = 1;
+  }
+  void add_bad_prime(Slice prime_str) const override {
+    cache[prime_str.str()] = 0;
+  }
+  mutable std::map<string, int> cache;
+};
+
+class FakeBinlog
+    : public BinlogInterface
+    , public Actor {
+ public:
+  FakeBinlog() {
+    register_actor("FakeBinlog", this).release();
+  }
+  void force_sync(Promise<> promise) override {
+    if (pending_events_.empty()) {
+      pending_events_.emplace_back();
+    }
+    pending_events_.back().promises_.push_back(std::move(promise));
+    pending_events_.back().sync_flag = true;
+    request_sync();
+  }
+  void request_sync() {
+    if (!has_request_sync) {
+      has_request_sync = true;
+      if (Random::fast(0, 4) == 0) {
+        set_timeout_in(Random::fast(0, 99) / 100.0 * 0.005 + 0.001);
+      } else {
+        yield();
+      }
+    }
+  }
+  void force_flush() override {
+  }
+
+  uint64 next_id() override {
+    auto res = last_id_;
+    last_id_++;
+    return res;
+  }
+  uint64 next_id(int32 shift) override {
+    auto res = last_id_;
+    last_id_ += shift;
+    return res;
+  }
+  template <class F>
+  void for_each(const F &f) {
+    events_processor_.for_each([&](auto &x) {
+      LOG(INFO) << "REPLAY: " << x.id_;
+      f(x);
+    });
+  }
+
+  void restart() {
+    has_request_sync = false;
+    cancel_timeout();
+    for (auto &pending : pending_events_) {
+      auto &event = pending.event;
+      if (!event.empty()) {
+        // LOG(ERROR) << "FORGET EVENT: " << event.id_ << " " << event;
+      }
+    }
+    pending_events_.clear();
+  }
+
+  void change_key(DbKey key, Promise<> promise) override {
+  }
+
+ protected:
+  void close_impl(Promise<> promise) override {
+  }
+  void close_and_destroy_impl(Promise<> promise) override {
+  }
+  void add_raw_event_impl(uint64 id, BufferSlice &&raw_event, Promise<> promise) override {
+    auto event = BinlogEvent(std::move(raw_event));
+    LOG(INFO) << "ADD EVENT: " << event.id_ << " " << event;
+    pending_events_.emplace_back();
+    pending_events_.back().event = std::move(event);
+    pending_events_.back().promises_.push_back(std::move(promise));
+  }
+  void do_force_sync() {
+    if (pending_events_.empty()) {
+      return;
+    }
+    cancel_timeout();
+    has_request_sync = false;
+    auto pos = static_cast<size_t>(Random::fast_uint64() % pending_events_.size());
+    // pos = pending_events_.size() - 1;
+    std::vector<Promise<>> promises;
+    for (size_t i = 0; i <= pos; i++) {
+      auto &pending = pending_events_[i];
+      auto event = std::move(pending.event);
+      if (!event.empty()) {
+        LOG(INFO) << "SAVE EVENT: " << event.id_ << " " << event;
+        events_processor_.add_event(std::move(event));
+      }
+      append(promises, std::move(pending.promises_));
+    }
+    pending_events_.erase(pending_events_.begin(), pending_events_.begin() + pos + 1);
+    for (auto &promise : promises) {
+      promise.set_value(Unit());
+    }
+
+    for (auto &event : pending_events_) {
+      if (event.sync_flag) {
+        request_sync();
+        break;
+      }
+    }
+  }
+  void timeout_expired() override {
+    do_force_sync();
+  }
+  void wakeup() override {
+    if (has_request_sync) {
+      do_force_sync();
+    }
+  }
+  bool has_request_sync = false;
+  uint64 last_id_ = 1;
+  detail::BinlogEventsProcessor events_processor_;
+
+  struct PendingEvent {
+    BinlogEvent event;
+    bool sync_flag = false;
+    std::vector<Promise<>> promises_;
+  };
+
+  std::vector<PendingEvent> pending_events_;
+};
+
+using FakeKeyValue = BinlogKeyValue<BinlogInterface>;
+class OldFakeKeyValue : public KeyValueSyncInterface {
+  SeqNo set(string key, string value) override {
+    kv_[key] = value;
+    return 0;
+  }
+
+  SeqNo erase(const string &key) override {
+    kv_.erase(key);
+    return 0;
+  }
+
+  bool isset(const string &key) override {
+    return kv_.count(key) > 0;
+  }
+
+  string get(const string &key) override {
+    auto it = kv_.find(key);
+    if (it != kv_.end()) {
+      return it->second;
+    }
+    return string();
+  }
+
+ private:
+  std::map<string, string> kv_;
+};
+
+class Master;
+class FakeSecretChatContext : public SecretChatActor::Context {
+ public:
+  FakeSecretChatContext(std::shared_ptr<BinlogInterface> binlog, std::shared_ptr<KeyValueSyncInterface> key_value,
+                        std::shared_ptr<bool> close_flag, ActorShared<Master> master)
+      : binlog_(std::move(binlog))
+      , key_value_(std::move(key_value))
+      , close_flag_(std::move(close_flag))
+      , master_(std::move(master)) {
+    secret_chat_db_ = std::make_unique<SecretChatDb>(key_value_, 1);
+    net_query_creator_.stop_check();  // :(
+  }
+  DhCallback *dh_callback() override {
+    return &fake_dh_callback_;
+  }
+  NetQueryCreator &net_query_creator() override {
+    return net_query_creator_;
+  }
+  int32 unix_time() override {
+    return static_cast<int32>(std::time(nullptr));
+  }
+  bool close_flag() override {
+    return *close_flag_;
+  }
+  BinlogInterface *binlog() override {
+    return binlog_.get();
+  }
+  SecretChatDb *secret_chat_db() override {
+    return secret_chat_db_.get();
+  }
+  std::shared_ptr<DhConfig> dh_config() override {
+    static auto config = [] {
+      DhConfig dh_config;
+      dh_config.version = 12;
+      dh_config.g = g;
+      dh_config.prime = base64url_decode(prime_base64).move_as_ok();
+      return std::make_shared<DhConfig>(dh_config);
+    }();
+
+    return config;
+  }
+  void set_dh_config(std::shared_ptr<DhConfig> dh_config) override {
+    // empty
+  }
+
+  bool get_config_option_boolean(const string &name) const override {
+    return false;
+  }
+
+  // We don't want to expose the whole NetQueryDispatcher, MessagesManager and ContactsManager.
+  // So it is more clear which parts of MessagesManager is really used. And it is much easier to create tests.
+  void send_net_query(NetQueryPtr query, ActorShared<NetQueryCallback> callback, bool ordered) override;
+
+  void on_update_secret_chat(int64 access_hash, UserId user_id, SecretChatState state, bool is_outbound, int32 ttl,
+                             int32 date, string key_hash, int32 layer) override {
+  }
+
+  void on_inbound_message(UserId user_id, MessageId message_id, int32 date,
+                          tl_object_ptr<telegram_api::encryptedFile> file,
+                          tl_object_ptr<secret_api::decryptedMessage> message, Promise<>) override;
+
+  void on_send_message_error(int64 random_id, Status error, Promise<>) override;
+  void on_send_message_ack(int64 random_id) override;
+  void on_send_message_ok(int64 random_id, MessageId message_id, int32 date,
+                          tl_object_ptr<telegram_api::EncryptedFile> file, Promise<>) override;
+  void on_delete_messages(std::vector<int64> random_id, Promise<>) override;
+  void on_flush_history(MessageId, Promise<>) override;
+  void on_read_message(int64, Promise<>) override;
+
+  void on_screenshot_taken(UserId user_id, MessageId message_id, int32 date, int64 random_id,
+                           Promise<> promise) override {
+  }
+  void on_set_ttl(UserId user_id, MessageId message_id, int32 date, int32 ttl, int64 random_id,
+                  Promise<> promise) override {
+  }
+
+ private:
+  FakeDhCallback fake_dh_callback_;
+  static NetQueryCreator net_query_creator_;
+  std::shared_ptr<BinlogInterface> binlog_;
+  std::shared_ptr<KeyValueSyncInterface> key_value_;
+  std::shared_ptr<bool> close_flag_;
+  ActorShared<Master> master_;
+
+  std::shared_ptr<SecretChatDb> secret_chat_db_;
+};
+NetQueryCreator FakeSecretChatContext::net_query_creator_;
+
+class Master : public Actor {
+ public:
+  explicit Master(Status *status) : status_(status) {
+  }
+  class SecretChatProxy : public Actor {
+   public:
+    SecretChatProxy(string name, ActorShared<Master> parent) : name_(std::move(name)) {
+      binlog_ = std::make_shared<FakeBinlog>();
+      key_value_ = std::make_shared<FakeKeyValue>();
+      key_value_->external_init_begin(LogEvent::HandlerType::BinlogPmcMagic);
+      key_value_->external_init_finish(binlog_);
+      close_flag_ = std::make_shared<bool>(false);
+      parent_ = parent.get();
+      parent_token_ = parent.token();
+      actor_ = create_actor<SecretChatActor>(
+          "SecretChat " + name_, 123,
+          std::make_unique<FakeSecretChatContext>(binlog_, key_value_, close_flag_, std::move(parent)), true);
+      on_binlog_replay_finish();
+    }
+
+    ActorOwn<SecretChatActor> actor_;
+
+    void add_inbound_message(int32 chat_id, BufferSlice data, uint64 crc) {
+      CHECK(crc64(data.as_slice()) == crc);
+      auto event = std::make_unique<logevent::InboundSecretMessage>();
+      event->qts = 0;
+      event->chat_id = chat_id;
+      event->date = 0;
+      event->encrypted_message = std::move(data);
+      event->qts_ack = PromiseCreator::lambda(
+          [actor_id = actor_id(this), chat_id, data = event->encrypted_message.copy(), crc](Result<> result) mutable {
+            if (result.is_ok()) {
+              LOG(INFO) << "FINISH add_inbound_message " << tag("crc", crc);
+              return;
+            }
+            LOG(INFO) << "RESEND add_inbound_message " << tag("crc", crc) << result.error();
+            send_closure(actor_id, &SecretChatProxy::add_inbound_message, chat_id, std::move(data), crc);
+          });
+
+      add_event(Event::delayed_closure(&SecretChatActor::add_inbound_message, std::move(event)));
+    }
+
+    void send_message(tl_object_ptr<secret_api::decryptedMessage> message) {
+      BufferSlice serialized_message(serialize(*message));
+      auto resend_promise = PromiseCreator::lambda(
+          [actor_id = actor_id(this), serialized_message = std::move(serialized_message)](Result<> result) mutable {
+            TlBufferParser parser(&serialized_message);
+            auto message = secret_api::decryptedMessage::fetch(parser);
+            if (result.is_ok()) {
+              LOG(INFO) << "FINISH send_message " << tag("message", to_string(message));
+              return;
+            }
+            LOG(INFO) << "RESEND send_message " << tag("message", to_string(message)) << result.error();
+            CHECK(serialize(*message) == serialized_message.as_slice());
+            send_closure(actor_id, &SecretChatProxy::send_message, std::move(message));
+          });
+      auto sync_promise = PromiseCreator::lambda([actor_id = actor_id(this), generation = this->binlog_generation_,
+                                                  resend_promise = std::move(resend_promise)](Result<> result) mutable {
+        if (result.is_error()) {
+          resend_promise.set_error(result.move_as_error());
+          return;
+        }
+        send_closure(actor_id, &SecretChatProxy::sync_binlog, generation, std::move(resend_promise));
+      });
+
+      add_event(
+          Event::delayed_closure(&SecretChatActor::send_message, std::move(message), nullptr, std::move(sync_promise)));
+    }
+    int32 binlog_generation_ = 0;
+    void sync_binlog(int32 binlog_generation, Promise<> promise) {
+      if (binlog_generation != binlog_generation_) {
+        return promise.set_error(Status::Error("binlog generation mismatch"));
+      }
+      binlog_->force_sync(std::move(promise));
+    }
+    void on_closed() {
+      LOG(INFO) << "CLOSED";
+      ready_ = false;
+      *close_flag_ = false;
+
+      key_value_ = std::make_shared<FakeKeyValue>();
+      key_value_->external_init_begin(LogEvent::HandlerType::BinlogPmcMagic);
+
+      std::vector<BinlogEvent> events;
+      binlog_generation_++;
+      binlog_->restart();
+      binlog_->for_each([&](const BinlogEvent &event) {
+        if (event.type_ == LogEvent::HandlerType::BinlogPmcMagic) {
+          key_value_->external_init_handle(event);
+        } else {
+          events.push_back(event.clone());
+        }
+      });
+
+      key_value_->external_init_finish(binlog_);
+
+      actor_ = create_actor<SecretChatActor>(
+          "SecretChat " + name_, 123,
+          std::make_unique<FakeSecretChatContext>(binlog_, key_value_, close_flag_,
+                                                  ActorShared<Master>(parent_, parent_token_)),
+          true);
+
+      for (auto &event : events) {
+        CHECK(event.type_ == LogEvent::HandlerType::SecretChats);
+        auto r_message = logevent::SecretChatEvent::from_buffer_slice(event.data_as_buffer_slice());
+        LOG_IF(FATAL, r_message.is_error()) << "Failed to deserialize event: " << r_message.error();
+        auto message = r_message.move_as_ok();
+        message->set_logevent_id(event.id_);
+        LOG(INFO) << "Process binlog event " << *message;
+        switch (message->get_type()) {
+          case logevent::SecretChatEvent::Type::InboundSecretMessage:
+            send_closure_later(actor_, &SecretChatActor::replay_inbound_message,
+                               std::unique_ptr<logevent::InboundSecretMessage>(
+                                   static_cast<logevent::InboundSecretMessage *>(message.release())));
+            break;
+          case logevent::SecretChatEvent::Type::OutboundSecretMessage:
+            send_closure_later(actor_, &SecretChatActor::replay_outbound_message,
+                               std::unique_ptr<logevent::OutboundSecretMessage>(
+                                   static_cast<logevent::OutboundSecretMessage *>(message.release())));
+            break;
+          default:
+            UNREACHABLE();
+        }
+      };
+      start_test();
+      on_binlog_replay_finish();
+    }
+    void on_binlog_replay_finish() {
+      ready_ = true;
+      LOG(INFO) << "on_binlog_replay_finish!";
+      send_closure(actor_, &SecretChatActor::binlog_replay_finish);
+      for (auto &event : pending_events_) {
+        send_event(actor_, std::move(event));
+      }
+      pending_events_.clear();
+    }
+    void start_test() {
+      set_timeout_in(Random::fast(50, 99) * 0.3 / 50);
+      events_cnt_ = 0;
+    }
+
+   private:
+    string name_;
+
+    ActorId<Master> parent_;
+    uint64 parent_token_;
+    std::shared_ptr<FakeBinlog> binlog_;
+    std::shared_ptr<FakeKeyValue> key_value_;
+    std::shared_ptr<bool> close_flag_;
+    int events_cnt_ = 0;
+
+    std::vector<Event> pending_events_;
+    bool ready_ = false;
+
+    bool is_active() {
+      return !actor_.empty() && ready_;
+    }
+    void add_event(Event event) {
+      events_cnt_++;
+      if (is_active()) {
+        LOG(INFO) << "EMIT";
+        send_event(actor_, std::move(event));
+      } else {
+        LOG(INFO) << "DELAY";
+        pending_events_.push_back(std::move(event));
+      }
+    }
+
+    int32 bad_cnt_ = 0;
+    void timeout_expired() override {
+      LOG(INFO) << "TIMEOUT EXPIRED";
+      if (events_cnt_ < 4) {
+        bad_cnt_++;
+        CHECK(bad_cnt_ < 10);
+      } else {
+        bad_cnt_ = 0;
+      }
+      *close_flag_ = true;
+      actor_.reset();
+    }
+  };
+
+  auto &get_by_id(uint64 id) {
+    if (id == 1) {
+      return alice_;
+    } else {
+      return bob_;
+    }
+  }
+  auto &from() {
+    return get_by_id(get_link_token());
+  }
+  auto &to() {
+    return get_by_id(3 - get_link_token());
+  }
+  void start_up() override {
+    set_context(std::make_shared<Global>());
+    alice_ = create_actor<SecretChatProxy>("SecretChatProxy alice", "alice", actor_shared(this, 1));
+    bob_ = create_actor<SecretChatProxy>("SecretChatProxy bob", "bob", actor_shared(this, 2));
+    send_closure(alice_->get_actor_unsafe()->actor_, &SecretChatActor::create_chat, 2, 0, 123,
+                 PromiseCreator::lambda([actor_id = actor_id(this)](Result<SecretChatId> res) {
+                   send_closure(actor_id, &Master::got_secret_chat_id, std::move(res), 0);
+                 }));
+  }
+  void got_secret_chat_id(Result<SecretChatId> res, int) {  // second parameter is needed to workaround clang bug
+    CHECK(res.is_ok());
+    auto id = res.move_as_ok();
+    LOG(INFO) << "SecretChatId = " << id;
+  }
+  bool can_fail(NetQueryPtr &query) {
+    static int cnt = 20;
+    if (cnt > 0) {
+      cnt--;
+      return false;
+    }
+    if (query->tl_constructor() == telegram_api::messages_sendEncrypted::ID ||
+        query->tl_constructor() == telegram_api::messages_sendEncryptedFile::ID) {
+      return true;
+    }
+    return false;
+  }
+  void send_net_query(NetQueryPtr query, ActorShared<NetQueryCallback> callback, bool ordered) {
+    if (can_fail(query) && Random::fast(0, 1) == 0) {
+      LOG(INFO) << "Fail query " << query;
+      auto resend_promise =
+          PromiseCreator::lambda([id = actor_shared(this, get_link_token()), callback_actor = callback.get(),
+                                  callback_token = callback.token()](Result<NetQueryPtr> r_net_query) mutable {
+            if (r_net_query.is_error()) {
+              id.release();
+              return;
+            }
+            send_closure(std::move(id), &Master::send_net_query, r_net_query.move_as_ok(),
+                         ActorShared<NetQueryCallback>(callback_actor, callback_token), true);
+          });
+      query->set_error(Status::Error(429, "Test error"));
+      send_closure(std::move(callback), &NetQueryCallback::on_result_resendable, std::move(query),
+                   std::move(resend_promise));
+      return;
+    } else {
+      LOG(INFO) << "Do not fail " << query;
+    }
+    auto query_slice = query->query().clone();
+    if (query->gzip_flag() == NetQuery::GzipFlag::On) {
+      query_slice = gzdecode(query_slice.as_slice());
+    }
+    TlBufferParser parser(&query_slice);
+    //auto object = telegram_api::Function::fetch(parser);
+    //LOG(INFO) << query_slice.size();
+    //parser.get_status().ensure();
+    my_api::downcast_call(parser, [&](auto &object) {
+      this->process_net_query(std::move(object), std::move(query), std::move(callback));
+    });
+  }
+  template <class T>
+  void process_net_query(T &&object, NetQueryPtr query, ActorShared<NetQueryCallback> callback) {
+    LOG(FATAL) << "Unsupported query: " << to_string(object);
+  }
+  void process_net_query(my_api::messages_getDhConfig &&get_dh_config, NetQueryPtr net_query,
+                         ActorShared<NetQueryCallback> callback) {
+    //LOG(INFO) << "Got query " << to_string(get_dh_config);
+    my_api::messages_dhConfig config;
+    config.p_ = BufferSlice(base64url_decode(prime_base64).move_as_ok());
+    config.g_ = g;
+    config.version_ = 12;
+    auto storer = TLObjectStorer<my_api::messages_dhConfig>(config);
+    BufferSlice answer(storer.size());
+    storer.store(answer.as_slice().ubegin());
+    net_query->set_ok(std::move(answer));
+    send_closure(std::move(callback), &NetQueryCallback::on_result, std::move(net_query));
+  }
+  void process_net_query(my_api::messages_requestEncryption &&request_encryption, NetQueryPtr net_query,
+                         ActorShared<NetQueryCallback> callback) {
+    CHECK(get_link_token() == 1);
+    send_closure(alice_->get_actor_unsafe()->actor_, &SecretChatActor::update_chat,
+                 make_tl_object<telegram_api::encryptedChatWaiting>(123, 321, 0, 1, 2));
+    send_closure(
+        bob_->get_actor_unsafe()->actor_, &SecretChatActor::update_chat,
+        make_tl_object<telegram_api::encryptedChatRequested>(123, 321, 0, 1, 2, request_encryption.g_a_.clone()));
+    net_query->clear();
+  }
+  void process_net_query(my_api::messages_acceptEncryption &&request_encryption, NetQueryPtr net_query,
+                         ActorShared<NetQueryCallback> callback) {
+    CHECK(get_link_token() == 2);
+    send_closure(alice_->get_actor_unsafe()->actor_, &SecretChatActor::update_chat,
+                 make_tl_object<telegram_api::encryptedChat>(123, 321, 0, 1, 2, request_encryption.g_b_.clone(),
+                                                             request_encryption.key_fingerprint_));
+
+    my_api::encryptedChat encrypted_chat(123, 321, 0, 1, 2, BufferSlice(), request_encryption.key_fingerprint_);
+    auto storer = TLObjectStorer<my_api::encryptedChat>(encrypted_chat);
+    BufferSlice answer(storer.size());
+    storer.store(answer.as_slice().ubegin());
+    net_query->set_ok(std::move(answer));
+    send_closure(std::move(callback), &NetQueryCallback::on_result, std::move(net_query));
+    send_closure(alice_, &SecretChatProxy::start_test);
+    send_closure(bob_, &SecretChatProxy::start_test);
+    send_ping(1, 5000);
+    set_timeout_in(1);
+  }
+  void timeout_expired() override {
+    send_message(1, "oppa");
+    send_message(2, "appo");
+    set_timeout_in(1);
+  }
+  void send_ping(int id, int cnt) {
+    if (cnt % 200 == 0) {
+      LOG(ERROR) << "send ping " << tag("id", id) << tag("cnt", cnt);
+    } else {
+      LOG(INFO) << "send ping " << tag("id", id) << tag("cnt", cnt);
+    }
+    string text = PSTRING() << "PING: " << cnt;
+    send_message(id, std::move(text));
+  }
+  void send_message(int id, string text) {
+    auto random_id = Random::secure_int64();
+    LOG(INFO) << "send message: " << tag("id", id) << tag("text", text) << tag("random_id", random_id);
+    sent_messages_[random_id] = Message{id, text};
+    send_closure(get_by_id(id), &SecretChatProxy::send_message,
+                 secret_api::make_object<secret_api::decryptedMessage>(0, random_id, 0, text, Auto(), Auto(), Auto(),
+                                                                       Auto(), 0));
+  }
+  void process_net_query(my_api::messages_sendEncryptedService &&message, NetQueryPtr net_query,
+                         ActorShared<NetQueryCallback> callback) {
+    process_net_query_send_enrypted(std::move(message.data_), std::move(net_query), std::move(callback));
+  }
+  void process_net_query(my_api::messages_sendEncrypted &&message, NetQueryPtr net_query,
+                         ActorShared<NetQueryCallback> callback) {
+    process_net_query_send_enrypted(std::move(message.data_), std::move(net_query), std::move(callback));
+  }
+  void process_net_query_send_enrypted(BufferSlice data, NetQueryPtr net_query,
+                                       ActorShared<NetQueryCallback> callback) {
+    my_api::messages_sentEncryptedMessage sent_message;
+    sent_message.date_ = 0;
+    auto storer = TLObjectStorer<my_api::messages_sentEncryptedMessage>(sent_message);
+    BufferSlice answer(storer.size());
+    storer.store(answer.as_slice().ubegin());
+    net_query->set_ok(std::move(answer));
+    send_closure(std::move(callback), &NetQueryCallback::on_result, std::move(net_query));
+
+    // We can't loose updates yet :(
+    auto crc = crc64(data.as_slice());
+    LOG(INFO) << "send SecretChatProxy::add_inbound_message" << tag("crc", crc);
+    send_closure(to(), &SecretChatProxy::add_inbound_message, narrow_cast<int32>(3 - get_link_token()), std::move(data),
+                 crc);
+  }
+
+  int32 last_ping_ = std::numeric_limits<int32>::max();
+  void on_inbound_message(string message, Promise<> promise) {
+    promise.set_value(Unit());
+    LOG(INFO) << "GOT INBOUND MESSAGE: " << message << " " << get_link_token();
+    int32 cnt;
+    int x = std::sscanf(message.c_str(), "PING: %d", &cnt);
+    if (x != 1) {
+      return;
+    }
+    if (cnt == 0) {
+      Scheduler::instance()->finish();
+      *status_ = Status::OK();
+      return;
+    }
+    if (cnt >= last_ping_) {
+      return;
+    }
+    last_ping_ = cnt;
+    send_ping(narrow_cast<int32>(get_link_token()), cnt - 1);
+  }
+  void on_send_message_error(int64 random_id, Status error, Promise<> promise) {
+    promise.set_value(Unit());
+    LOG(INFO) << "on_send_message_error: " << tag("random_id", random_id) << error;
+    auto it = sent_messages_.find(random_id);
+    if (it == sent_messages_.end()) {
+      LOG(INFO) << "TODO: try fix errors about message after it is sent";
+      return;
+    }
+    CHECK(it != sent_messages_.end());
+    auto message = it->second;
+    // sent_messages_.erase(it);
+    send_message(message.id, message.text);
+  }
+  void on_send_message_ok(int64 random_id, Promise<> promise) {
+    promise.set_value(Unit());
+    LOG(INFO) << "on_send_message_ok: " << tag("random_id", random_id);
+    auto it = sent_messages_.find(random_id);
+    if (it == sent_messages_.end()) {
+      LOG(INFO) << "TODO: try fix errors about message after it is sent";
+      return;
+    }
+    CHECK(it != sent_messages_.end());
+    // sent_messages_.erase(it);
+  }
+
+ private:
+  Status *status_;
+  ActorOwn<SecretChatProxy> alice_;
+  ActorOwn<SecretChatProxy> bob_;
+  struct Message {
+    int32 id;
+    string text;
+  };
+  std::map<int64, Message> sent_messages_;
+
+  void hangup_shared() override {
+    LOG(INFO) << "GOT HANGUP: " << get_link_token();
+    send_closure(from(), &SecretChatProxy::on_closed);
+  }
+};
+
+void FakeSecretChatContext::send_net_query(NetQueryPtr query, ActorShared<NetQueryCallback> callback, bool ordered) {
+  send_closure(master_, &Master::send_net_query, std::move(query), std::move(callback), ordered);
+}
+void FakeSecretChatContext::on_inbound_message(UserId user_id, MessageId message_id, int32 date,
+                                               tl_object_ptr<telegram_api::encryptedFile> file,
+                                               tl_object_ptr<secret_api::decryptedMessage> message, Promise<> promise) {
+  send_closure(master_, &Master::on_inbound_message, message->message_, std::move(promise));
+}
+void FakeSecretChatContext::on_send_message_error(int64 random_id, Status error, Promise<> promise) {
+  send_closure(master_, &Master::on_send_message_error, random_id, std::move(error), std::move(promise));
+}
+void FakeSecretChatContext::on_send_message_ack(int64 random_id) {
+}
+void FakeSecretChatContext::on_send_message_ok(int64 random_id, MessageId message_id, int32 date,
+                                               tl_object_ptr<telegram_api::EncryptedFile> file, Promise<> promise) {
+  send_closure(master_, &Master::on_send_message_ok, random_id, std::move(promise));
+}
+void FakeSecretChatContext::on_delete_messages(std::vector<int64> random_id, Promise<> promise) {
+  promise.set_value(Unit());
+}
+void FakeSecretChatContext::on_flush_history(MessageId, Promise<> promise) {
+  promise.set_error(Status::Error("unsupported"));
+}
+void FakeSecretChatContext::on_read_message(int64, Promise<> promise) {
+  promise.set_error(Status::Error("unsupported"));
+}
+
+TEST(Secret, go) {
+  SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR));
+  ConcurrentScheduler sched;
+  int threads_n = 0;
+  sched.init(threads_n);
+
+  Status result;
+  sched.create_actor_unsafe<Master>(0, "HandshakeTestActor", &result).release();
+  sched.start();
+  while (sched.run_main(10)) {
+    // empty;
+  }
+  sched.finish();
+
+  if (result.is_error()) {
+    LOG(ERROR) << result;
+  }
+  ASSERT_TRUE(result.is_ok());
+}
+
+}  // namespace td
diff --git a/libs/tdlib/td/test/string_cleaning.cpp b/libs/tdlib/td/test/string_cleaning.cpp
new file mode 100644
index 0000000000..6fbd8150a4
--- /dev/null
+++ b/libs/tdlib/td/test/string_cleaning.cpp
@@ -0,0 +1,107 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/misc.h"
+
+#include "td/utils/Slice.h"
+#include "td/utils/tests.h"
+
+REGISTER_TESTS(string_cleaning);
+
+using namespace td;
+
+TEST(StringCleaning, clean_name) {
+  ASSERT_EQ("@mention", clean_name("@mention", 1000000));
+  ASSERT_EQ("@mention", clean_name("     @mention    ", 1000000));
+  ASSERT_EQ("@MENTION", clean_name("@MENTION", 1000000));
+  ASSERT_EQ("ЛШТШФУМ", clean_name("ЛШТШФУМ", 1000000));
+  ASSERT_EQ("....", clean_name("....", 1000000));
+  ASSERT_EQ(". ASD ..", clean_name(".   ASD   ..", 1000000));
+  ASSERT_EQ(". ASD", clean_name(".   ASD   ..", 10));
+  ASSERT_EQ(". ASD", clean_name(".\n\n\nASD\n\n\n..", 10));
+  ASSERT_EQ("", clean_name("\n\n\n\n\n\n", 1000000));
+  ASSERT_EQ("", clean_name("\xC2\xA0\xC2\xA0\xC2\xA0\xC2\xA0\xC2\xA0\n\n\n\n\n\n      \n\xC2\xA0 \xC2\xA0 \n", 100000));
+  ASSERT_EQ("abc", clean_name("\xC2\xA0\xC2\xA0"
+                              "abc\xC2\xA0\xC2\xA0\xC2\xA0\xC2\xA0",
+                              1000000));
+};
+
+TEST(StringCleaning, clean_username) {
+  ASSERT_EQ("@mention", clean_username("@mention"));
+  ASSERT_EQ("@mention", clean_username("     @mention    "));
+  ASSERT_EQ("@mention", clean_username("@MENTION"));
+  ASSERT_EQ("ЛШТШФУМ", clean_username("ЛШТШФУМ"));
+  ASSERT_EQ("", clean_username("...."));
+  ASSERT_EQ("asd", clean_username(".   ASD   .."));
+};
+
+static void check_clean_input_string(string str, string expected, bool expected_result) {
+  auto result = clean_input_string(str);
+  ASSERT_EQ(expected_result, result);
+  if (result) {
+    ASSERT_EQ(expected, str);
+  }
+}
+
+TEST(StringCleaning, clean_input_string) {
+  check_clean_input_string("/abc", "/abc", true);
+  check_clean_input_string(string(50000, 'a'), string(34996, 'a'), true);
+  check_clean_input_string("\xff", "", false);
+  check_clean_input_string("\xc0\x80", "", false);
+  check_clean_input_string("\xd0", "", false);
+  check_clean_input_string("\xe0\xaf", "", false);
+  check_clean_input_string("\xf0\xa6", "", false);
+  check_clean_input_string("\xf0\xa6\x88", "", false);
+  check_clean_input_string("\xf4\x8f\xbf\xbf", "\xf4\x8f\xbf\xbf", true);
+  check_clean_input_string("\xf4\x8f\xbf\xc0", "", false);
+  check_clean_input_string("\r\r\r\r\r\r\r", "", true);
+  check_clean_input_string("\r\n\r\n\r\n\r\n\r\n\r\n\r", "\n\n\n\n\n\n", true);
+  check_clean_input_string(Slice("\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14"
+                                 "\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x20\x21")
+                               .str(),
+                           "          \x0a                     \x21", true);
+  check_clean_input_string(
+      "\xe2\x80\xa7\xe2\x80\xa8\xe2\x80\xa9\xe2\x80\xaa\xe2\x80\xab\xe2\x80\xac\xe2\x80\xad\xe2\x80\xae\xe2\x80\xaf",
+      "\xe2\x80\xa7\xe2\x80\xaf", true);
+  check_clean_input_string("\xcc\xb3\xcc\xbf\xcc\x8a", "", true);
+}
+
+static void check_strip_empty_characters(string str, size_t max_length, string expected) {
+  ASSERT_EQ(expected, strip_empty_characters(str, max_length));
+}
+
+TEST(StringCleaning, strip_empty_characters) {
+  check_strip_empty_characters("/abc", 4, "/abc");
+  check_strip_empty_characters("/abc", 3, "/ab");
+  check_strip_empty_characters("/abc", 0, "");
+  check_strip_empty_characters("/abc", 10000000, "/abc");
+  string spaces =
+      u8"\u1680\u180E\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u200B\u202F\u205F\u3000\uFEFF"
+      u8"\uFFFC\uFFFC";
+  string spaces_replace = "                    ";
+  string empty = "\xE2\x80\x8C\xE2\x80\x8D\xE2\x80\xAE\xC2\xA0\xC2\xA0";
+
+  check_strip_empty_characters(spaces, 1000000, "");
+  check_strip_empty_characters(empty, 1000000, "");
+  check_strip_empty_characters(empty + "a", 1000000, empty + "a");
+  check_strip_empty_characters(spaces + empty + spaces + "abc" + spaces, 1000000, empty + spaces_replace + "abc");
+  check_strip_empty_characters(spaces + spaces + empty + spaces + spaces + empty + empty, 1000000,
+                               empty + spaces_replace + spaces_replace + empty + empty);
+  check_strip_empty_characters("\r\r\r\r\r\r\r", 1000000, "");
+  check_strip_empty_characters("\r\n\r\n\r\n\r\n\r\n\r\n\r", 1000000, "");
+  check_strip_empty_characters(Slice(" \t\r\n\0\va\v\0\n\r\t ").str(), 1000000, "a");
+  check_strip_empty_characters(
+      Slice("\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14"
+            "\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x20\x21")
+          .str(),
+      1000000,
+      "\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14"
+      "\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x20\x21");
+  check_strip_empty_characters("\xcc\xb3\xcc\xbf\xcc\x8a", 2, "\xcc\xb3\xcc\xbf");
+  check_strip_empty_characters(
+      "\xe2\x80\xa7\xe2\x80\xa8\xe2\x80\xa9\xe2\x80\xaa\xe2\x80\xab\xe2\x80\xac\xe2\x80\xad\xe2\x80\xae", 3,
+      "\xe2\x80\xa7\xe2\x80\xa8\xe2\x80\xa9");
+}
diff --git a/libs/tdlib/td/test/tdclient.cpp b/libs/tdlib/td/test/tdclient.cpp
new file mode 100644
index 0000000000..7cef0fcbc0
--- /dev/null
+++ b/libs/tdlib/td/test/tdclient.cpp
@@ -0,0 +1,837 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "data.h"
+
+#include "td/actor/PromiseFuture.h"
+
+#include "td/telegram/ClientActor.h"
+
+#include "td/telegram/td_api.h"
+
+#include "td/utils/base64.h"
+#include "td/utils/BufferedFd.h"
+#include "td/utils/filesystem.h"
+#include "td/utils/format.h"
+#include "td/utils/logging.h"
+#include "td/utils/misc.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/port/path.h"
+#include "td/utils/Random.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+#include "td/utils/tests.h"
+
+#include <cstdio>
+#include <functional>
+#include <map>
+#include <memory>
+#include <utility>
+
+REGISTER_TESTS(tdclient);
+
+namespace td {
+
+template <class T>
+static void check_td_error(T &result) {
+  CHECK(result->get_id() != td_api::error::ID) << to_string(result);
+}
+
+static void rmrf(CSlice path) {
+  td::walk_path(path, [](CSlice path, bool is_dir) {
+    if (is_dir) {
+      td::rmdir(path).ignore();
+    } else {
+      td::unlink(path).ignore();
+    }
+  });
+}
+
+class TestClient : public Actor {
+ public:
+  explicit TestClient(string name) : name_(std::move(name)) {
+  }
+  struct Update {
+    uint64 id;
+    tl_object_ptr<td_api::Object> object;
+    Update(uint64 id, tl_object_ptr<td_api::Object> object) : id(id), object(std::move(object)) {
+    }
+  };
+  class Listener {
+   public:
+    Listener() = default;
+    Listener(const Listener &) = delete;
+    Listener &operator=(const Listener &) = delete;
+    Listener(Listener &&) = delete;
+    Listener &operator=(Listener &&) = delete;
+    virtual ~Listener() = default;
+    virtual void start_listen(TestClient *client) {
+    }
+    virtual void stop_listen() {
+    }
+    virtual void on_update(std::shared_ptr<Update> update) = 0;
+  };
+  void close(Promise<> close_promise) {
+    close_promise_ = std::move(close_promise);
+    td_.reset();
+  }
+
+  unique_ptr<TdCallback> make_td_callback() {
+    class TdCallbackImpl : public TdCallback {
+     public:
+      explicit TdCallbackImpl(ActorId<TestClient> client) : client_(client) {
+      }
+      void on_result(uint64 id, tl_object_ptr<td_api::Object> result) override {
+        send_closure(client_, &TestClient::on_result, id, std::move(result));
+      }
+      void on_error(uint64 id, tl_object_ptr<td_api::error> error) override {
+        send_closure(client_, &TestClient::on_error, id, std::move(error));
+      }
+      void on_closed() override {
+        send_closure(client_, &TestClient::on_closed);
+      }
+
+     private:
+      ActorId<TestClient> client_;
+    };
+    return make_unique<TdCallbackImpl>(actor_id(this));
+  }
+
+  void add_listener(std::unique_ptr<Listener> listener) {
+    auto *ptr = listener.get();
+    listeners_.push_back(std::move(listener));
+    ptr->start_listen(this);
+  }
+  void remove_listener(Listener *listener) {
+    pending_remove_.push_back(listener);
+  }
+  void do_pending_remove_listeners() {
+    for (auto listener : pending_remove_) {
+      do_remove_listener(listener);
+    }
+    pending_remove_.clear();
+  }
+  void do_remove_listener(Listener *listener) {
+    for (size_t i = 0; i < listeners_.size(); i++) {
+      if (listeners_[i].get() == listener) {
+        listener->stop_listen();
+        listeners_.erase(listeners_.begin() + i);
+        break;
+      }
+    }
+  }
+
+  void on_result(uint64 id, tl_object_ptr<td_api::Object> result) {
+    on_update(std::make_shared<Update>(id, std::move(result)));
+  }
+  void on_error(uint64 id, tl_object_ptr<td_api::error> error) {
+    on_update(std::make_shared<Update>(id, std::move(error)));
+  }
+  void on_update(std::shared_ptr<Update> update) {
+    for (auto &listener : listeners_) {
+      listener->on_update(update);
+    }
+    do_pending_remove_listeners();
+  }
+
+  void on_closed() {
+    stop();
+  }
+
+  void start_up() override {
+    rmrf(name_);
+    set_context(std::make_shared<td::ActorContext>());
+    set_tag(name_);
+    LOG(INFO) << "START UP!";
+
+    td_ = create_actor<ClientActor>("Td-proxy", make_td_callback());
+  }
+
+  ActorOwn<ClientActor> td_;
+
+  string name_;
+
+ private:
+  std::vector<std::unique_ptr<Listener>> listeners_;
+  std::vector<Listener *> pending_remove_;
+
+  Promise<> close_promise_;
+};
+
+class Task : public TestClient::Listener {
+ public:
+  void on_update(std::shared_ptr<TestClient::Update> update) override {
+    auto it = sent_queries_.find(update->id);
+    if (it != sent_queries_.end()) {
+      it->second(std::move(update->object));
+      sent_queries_.erase(it);
+    }
+    process_update(update);
+  }
+  void start_listen(TestClient *client) override {
+    client_ = client;
+    start_up();
+  }
+  virtual void process_update(std::shared_ptr<TestClient::Update> update) {
+  }
+
+  template <class F>
+  void send_query(tl_object_ptr<td_api::Function> function, F callback) {
+    auto id = current_query_id_++;
+    sent_queries_[id] = std::forward<F>(callback);
+    send_closure(client_->td_, &ClientActor::request, id, std::move(function));
+  }
+
+ protected:
+  std::map<uint64, std::function<void(tl_object_ptr<td_api::Object>)>> sent_queries_;
+  TestClient *client_;
+  uint64 current_query_id_ = 1;
+
+  virtual void start_up() {
+  }
+  void stop() {
+    client_->remove_listener(this);
+  }
+};
+
+class DoAuthentication : public Task {
+ public:
+  DoAuthentication(string name, string phone, string code, Promise<> promise)
+      : name_(std::move(name)), phone_(std::move(phone)), code_(std::move(code)), promise_(std::move(promise)) {
+  }
+  void start_up() override {
+    send_query(make_tl_object<td_api::getAuthorizationState>(),
+               [this](auto res) { this->process_authorization_state(std::move(res)); });
+  }
+  void process_authorization_state(tl_object_ptr<td_api::Object> authorization_state) {
+    start_flag_ = true;
+    tl_object_ptr<td_api::Function> function;
+    switch (authorization_state->get_id()) {
+      case td_api::authorizationStateWaitEncryptionKey::ID:
+        function = make_tl_object<td_api::checkDatabaseEncryptionKey>();
+        break;
+      case td_api::authorizationStateWaitPhoneNumber::ID:
+        function = make_tl_object<td_api::setAuthenticationPhoneNumber>(phone_, false, true);
+        break;
+      case td_api::authorizationStateWaitCode::ID:
+        function = make_tl_object<td_api::checkAuthenticationCode>(code_, name_, "");
+        break;
+      case td_api::authorizationStateWaitTdlibParameters::ID: {
+        auto parameters = td_api::make_object<td_api::tdlibParameters>();
+        parameters->use_test_dc_ = true;
+        parameters->database_directory_ = name_ + TD_DIR_SLASH;
+        parameters->use_message_database_ = true;
+        parameters->use_secret_chats_ = true;
+        parameters->api_id_ = 94575;
+        parameters->api_hash_ = "a3406de8d171bb422bb6ddf3bbd800e2";
+        parameters->system_language_code_ = "en";
+        parameters->device_model_ = "Desktop";
+        parameters->system_version_ = "Unknown";
+        parameters->application_version_ = "tdclient-test";
+        parameters->ignore_file_names_ = false;
+        parameters->enable_storage_optimizer_ = true;
+        function = td_api::make_object<td_api::setTdlibParameters>(std::move(parameters));
+        break;
+      }
+      case td_api::authorizationStateReady::ID:
+        on_authorization_ready();
+        return;
+      default:
+        CHECK(false) << "Unexpected authorization state " << to_string(authorization_state);
+    }
+    send_query(std::move(function), [this](auto res) { CHECK(res->get_id() == td_api::ok::ID) << to_string(res); });
+  }
+  void on_authorization_ready() {
+    LOG(INFO) << "GOT AUTHORIZED";
+    stop();
+  }
+
+ private:
+  string name_;
+  string phone_;
+  string code_;
+  Promise<> promise_;
+  bool start_flag_{false};
+  void process_update(std::shared_ptr<TestClient::Update> update) override {
+    if (!start_flag_) {
+      return;
+    }
+    if (!update->object) {
+      return;
+    }
+    if (update->object->get_id() == td_api::updateAuthorizationState::ID) {
+      auto o = std::move(update->object);
+      process_authorization_state(std::move(static_cast<td_api::updateAuthorizationState &>(*o).authorization_state_));
+    }
+  }
+};
+
+class SetUsername : public Task {
+ public:
+  SetUsername(string username, Promise<> promise) : username_(std::move(username)), promise_(std::move(promise)) {
+  }
+
+ private:
+  string username_;
+  Promise<> promise_;
+  int32 self_id_;
+  string tag_;
+
+  void start_up() override {
+    send_query(make_tl_object<td_api::getMe>(), [this](auto res) { this->process_me_user(std::move(res)); });
+  }
+
+  void process_me_user(tl_object_ptr<td_api::Object> res) {
+    CHECK(res->get_id() == td_api::user::ID);
+    auto user = move_tl_object_as<td_api::user>(res);
+    self_id_ = user->id_;
+    if (user->username_ != username_) {
+      LOG(INFO) << "SET USERNAME: " << username_;
+      send_query(make_tl_object<td_api::setUsername>(username_), [this](auto res) {
+        CHECK(res->get_id() == td_api::ok::ID);
+        this->send_self_message();
+      });
+    } else {
+      send_self_message();
+    }
+  }
+  void send_self_message() {
+    tag_ = PSTRING() << format::as_hex(Random::secure_int64());
+
+    send_query(make_tl_object<td_api::createPrivateChat>(self_id_, false), [this](auto res) {
+      CHECK(res->get_id() == td_api::chat::ID);
+      auto chat = move_tl_object_as<td_api::chat>(res);
+      this->send_query(
+          make_tl_object<td_api::sendMessage>(
+              chat->id_, 0, false, false, nullptr,
+              make_tl_object<td_api::inputMessageText>(
+                  make_tl_object<td_api::formattedText>(PSTRING() << tag_ << " INIT", Auto()), false, false)),
+          [](auto res) {});
+    });
+  }
+
+  void process_update(std::shared_ptr<TestClient::Update> update) override {
+    if (!update->object) {
+      return;
+    }
+    if (update->object->get_id() == td_api::updateMessageSendSucceeded::ID) {
+      auto updateNewMessage = move_tl_object_as<td_api::updateMessageSendSucceeded>(update->object);
+      auto &message = updateNewMessage->message_;
+      if (message->content_->get_id() == td_api::messageText::ID) {
+        auto messageText = move_tl_object_as<td_api::messageText>(message->content_);
+        auto text = messageText->text_->text_;
+        if (text.substr(0, tag_.size()) == tag_) {
+          LOG(INFO) << "GOT SELF MESSAGE";
+          return stop();
+        }
+      }
+    }
+  }
+};
+
+class CheckTestA : public Task {
+ public:
+  CheckTestA(string tag, Promise<> promise) : tag_(std::move(tag)), promise_(std::move(promise)) {
+  }
+
+ private:
+  string tag_;
+  Promise<> promise_;
+  string previous_text_;
+  int cnt_ = 20;
+  void process_update(std::shared_ptr<TestClient::Update> update) override {
+    if (update->object->get_id() == td_api::updateNewMessage::ID) {
+      auto updateNewMessage = move_tl_object_as<td_api::updateNewMessage>(update->object);
+      auto &message = updateNewMessage->message_;
+      if (message->content_->get_id() == td_api::messageText::ID) {
+        auto messageText = move_tl_object_as<td_api::messageText>(message->content_);
+        auto text = messageText->text_->text_;
+        if (text.substr(0, tag_.size()) == tag_) {
+          CHECK(text > previous_text_) << tag("now", text) << tag("previous", previous_text_);
+          previous_text_ = text;
+          cnt_--;
+          LOG(INFO) << "GOT " << tag("text", text) << tag("left", cnt_);
+          if (cnt_ == 0) {
+            return stop();
+          }
+        }
+      }
+    }
+  }
+};
+
+class TestA : public Task {
+ public:
+  TestA(string tag, string username) : tag_(std::move(tag)), username_(std::move(username)) {
+  }
+  void start_up() override {
+    send_query(make_tl_object<td_api::searchPublicChat>(username_), [this](auto res) {
+      CHECK(res->get_id() == td_api::chat::ID);
+      auto chat = move_tl_object_as<td_api::chat>(res);
+      for (int i = 0; i < 20; i++) {
+        this->send_query(make_tl_object<td_api::sendMessage>(
+                             chat->id_, 0, false, false, nullptr,
+                             make_tl_object<td_api::inputMessageText>(
+                                 make_tl_object<td_api::formattedText>(PSTRING() << tag_ << " " << (1000 + i), Auto()),
+                                 false, false)),
+                         [&](auto res) { this->stop(); });
+      }
+    });
+  }
+
+ private:
+  string tag_;
+  string username_;
+};
+
+class TestSecretChat : public Task {
+ public:
+  TestSecretChat(string tag, string username) : tag_(std::move(tag)), username_(std::move(username)) {
+  }
+
+  void start_up() override {
+    auto f = [this](auto res) {
+      CHECK(res->get_id() == td_api::chat::ID);
+      auto chat = move_tl_object_as<td_api::chat>(res);
+      this->chat_id_ = chat->id_;
+      this->secret_chat_id_ = move_tl_object_as<td_api::chatTypeSecret>(chat->type_)->secret_chat_id_;
+    };
+    send_query(make_tl_object<td_api::searchPublicChat>(username_), [this, f = std::move(f)](auto res) mutable {
+      CHECK(res->get_id() == td_api::chat::ID);
+      auto chat = move_tl_object_as<td_api::chat>(res);
+      CHECK(chat->type_->get_id() == td_api::chatTypePrivate::ID);
+      auto info = move_tl_object_as<td_api::chatTypePrivate>(chat->type_);
+      this->send_query(make_tl_object<td_api::createNewSecretChat>(info->user_id_), std::move(f));
+    });
+  }
+
+  void process_update(std::shared_ptr<TestClient::Update> update) override {
+    if (!update->object) {
+      return;
+    }
+    if (update->object->get_id() == td_api::updateSecretChat::ID) {
+      auto update_secret_chat = move_tl_object_as<td_api::updateSecretChat>(update->object);
+      if (update_secret_chat->secret_chat_->id_ != secret_chat_id_ ||
+          update_secret_chat->secret_chat_->state_->get_id() != td_api::secretChatStateReady::ID) {
+        return;
+      }
+      LOG(INFO) << "SEND ENCRYPTED MESSAGES";
+      for (int i = 0; i < 20; i++) {
+        send_query(make_tl_object<td_api::sendMessage>(
+                       chat_id_, 0, false, false, nullptr,
+                       make_tl_object<td_api::inputMessageText>(
+                           make_tl_object<td_api::formattedText>(PSTRING() << tag_ << " " << (1000 + i), Auto()), false,
+                           false)),
+                   [](auto res) {});
+      }
+    }
+  }
+
+ private:
+  string tag_;
+  string username_;
+  int64 secret_chat_id_ = 0;
+  int64 chat_id_ = 0;
+};
+
+class TestFileGenerated : public Task {
+ public:
+  TestFileGenerated(string tag, string username) : tag_(std::move(tag)), username_(std::move(username)) {
+  }
+
+  void start_up() override {
+  }
+
+  void process_update(std::shared_ptr<TestClient::Update> update) override {
+    if (!update->object) {
+      return;
+    }
+    if (update->object->get_id() == td_api::updateNewMessage::ID) {
+      auto updateNewMessage = move_tl_object_as<td_api::updateNewMessage>(update->object);
+      auto &message = updateNewMessage->message_;
+      chat_id_ = message->chat_id_;
+      if (message->content_->get_id() == td_api::messageText::ID) {
+        auto messageText = move_tl_object_as<td_api::messageText>(message->content_);
+        auto text = messageText->text_->text_;
+        if (text.substr(0, tag_.size()) == tag_) {
+          if (text.substr(tag_.size() + 1) == "ONE_FILE") {
+            return one_file();
+          }
+        }
+      }
+    } else if (update->object->get_id() == td_api::updateFileGenerationStart::ID) {
+      auto info = move_tl_object_as<td_api::updateFileGenerationStart>(update->object);
+      generate_file(info->generation_id_, info->original_path_, info->destination_path_, info->conversion_);
+    } else if (update->object->get_id() == td_api::updateFile::ID) {
+      auto file = move_tl_object_as<td_api::updateFile>(update->object);
+      LOG(INFO) << to_string(file);
+    }
+  }
+  void one_file() {
+    LOG(ERROR) << "Start ONE_FILE test";
+    string file_path = string("test_documents") + TD_DIR_SLASH + "a.txt";
+    mkpath(file_path).ensure();
+    auto raw_file =
+        FileFd::open(file_path, FileFd::Flags::Create | FileFd::Flags::Truncate | FileFd::Flags::Write).move_as_ok();
+    auto file = BufferedFd<FileFd>(std::move(raw_file));
+    for (int i = 1; i < 100000; i++) {
+      file.write(PSLICE() << i << "\n").ensure();
+    }
+    file.flush_write().ensure();  // important
+    file.close();
+    this->send_query(make_tl_object<td_api::sendMessage>(
+                         chat_id_, 0, false, false, nullptr,
+                         make_tl_object<td_api::inputMessageDocument>(
+                             make_tl_object<td_api::inputFileGenerated>(file_path, "square", 0),
+                             make_tl_object<td_api::inputThumbnail>(
+                                 make_tl_object<td_api::inputFileGenerated>(file_path, "thumbnail", 0), 0, 0),
+                             make_tl_object<td_api::formattedText>(tag_, Auto()))),
+                     [](auto res) { check_td_error(res); });
+
+    this->send_query(
+        make_tl_object<td_api::sendMessage>(chat_id_, 0, false, false, nullptr,
+                                            make_tl_object<td_api::inputMessageDocument>(
+                                                make_tl_object<td_api::inputFileGenerated>(file_path, "square", 0),
+                                                nullptr, make_tl_object<td_api::formattedText>(tag_, Auto()))),
+        [](auto res) { check_td_error(res); });
+  }
+
+  friend class GenerateFile;
+  class GenerateFile : public Actor {
+   public:
+    GenerateFile(Task *parent, int64 id, string original_path, string destination_path, string conversion)
+        : parent_(parent)
+        , id_(id)
+        , original_path_(std::move(original_path))
+        , destination_path_(std::move(destination_path))
+        , conversion_(std::move(conversion)) {
+    }
+
+   private:
+    Task *parent_;
+    int64 id_;
+    string original_path_;
+    string destination_path_;
+    string conversion_;
+
+    FILE *from = nullptr;
+    FILE *to = nullptr;
+
+    void start_up() override {
+      from = std::fopen(original_path_.c_str(), "rb");
+      CHECK(from);
+      to = std::fopen(destination_path_.c_str(), "wb");
+      CHECK(to);
+      yield();
+    }
+    void loop() override {
+      int cnt = 0;
+      while (true) {
+        uint32 x;
+        auto r = std::fscanf(from, "%u", &x);
+        if (r != 1) {
+          return stop();
+        }
+        std::fprintf(to, "%u\n", x * x);
+        if (++cnt >= 10000) {
+          break;
+        }
+      }
+      auto ready = std::ftell(to);
+      LOG(ERROR) << "READY: " << ready;
+      parent_->send_query(make_tl_object<td_api::setFileGenerationProgress>(
+                              id_, 1039823 /*yeah, exact size of this file*/, narrow_cast<int32>(ready)),
+                          [](auto result) { check_td_error(result); });
+      set_timeout_in(0.02);
+    }
+    void tear_down() override {
+      std::fclose(from);
+      std::fclose(to);
+      parent_->send_query(make_tl_object<td_api::finishFileGeneration>(id_, nullptr),
+                          [](auto result) { check_td_error(result); });
+    }
+  };
+  void generate_file(int64 id, string original_path, string destination_path, string conversion) {
+    LOG(ERROR) << "Generate file " << tag("id", id) << tag("original_path", original_path)
+               << tag("destination_path", destination_path) << tag("conversion", conversion);
+    if (conversion == "square") {
+      create_actor<GenerateFile>("GenerateFile", this, id, original_path, destination_path, conversion).release();
+    } else if (conversion == "thumbnail") {
+      write_file(destination_path, base64url_decode(Slice(thumbnail, thumbnail_size)).ok()).ensure();
+      this->send_query(make_tl_object<td_api::finishFileGeneration>(id, nullptr),
+                       [](auto result) { check_td_error(result); });
+    } else {
+      LOG(FATAL) << "unknown " << tag("conversion", conversion);
+    }
+  }
+
+ private:
+  string tag_;
+  string username_;
+  int64 chat_id_ = 0;
+};
+
+class CheckTestC : public Task {
+ public:
+  CheckTestC(string username, string tag, Promise<> promise)
+      : username_(std::move(username)), tag_(std::move(tag)), promise_(std::move(promise)) {
+  }
+
+  void start_up() override {
+    send_query(make_tl_object<td_api::searchPublicChat>(username_), [this](auto res) {
+      CHECK(res->get_id() == td_api::chat::ID);
+      auto chat = move_tl_object_as<td_api::chat>(res);
+      chat_id_ = chat->id_;
+      this->one_file();
+    });
+  }
+
+ private:
+  string username_;
+  string tag_;
+  Promise<> promise_;
+  int64 chat_id_;
+
+  void one_file() {
+    this->send_query(
+        make_tl_object<td_api::sendMessage>(
+            chat_id_, 0, false, false, nullptr,
+            make_tl_object<td_api::inputMessageText>(
+                make_tl_object<td_api::formattedText>(PSTRING() << tag_ << " ONE_FILE", Auto()), false, false)),
+        [](auto res) { check_td_error(res); });
+  }
+
+  void process_update(std::shared_ptr<TestClient::Update> update) override {
+    if (!update->object) {
+      return;
+    }
+    if (update->object->get_id() == td_api::updateNewMessage::ID) {
+      auto updateNewMessage = move_tl_object_as<td_api::updateNewMessage>(update->object);
+      auto &message = updateNewMessage->message_;
+      if (message->content_->get_id() == td_api::messageDocument::ID) {
+        auto messageDocument = move_tl_object_as<td_api::messageDocument>(message->content_);
+        auto text = messageDocument->caption_->text_;
+        if (text.substr(0, tag_.size()) == tag_) {
+          file_id_to_check_ = messageDocument->document_->document_->id_;
+          LOG(ERROR) << "GOT FILE " << to_string(messageDocument->document_->document_);
+          this->send_query(make_tl_object<td_api::downloadFile>(file_id_to_check_, 1),
+                           [](auto res) { check_td_error(res); });
+        }
+      }
+    } else if (update->object->get_id() == td_api::updateFile::ID) {
+      auto updateFile = move_tl_object_as<td_api::updateFile>(update->object);
+      if (updateFile->file_->id_ == file_id_to_check_ && (updateFile->file_->local_->is_downloading_completed_)) {
+        check_file(updateFile->file_->local_->path_);
+      }
+    }
+  }
+
+  void check_file(CSlice path) {
+    FILE *from = std::fopen(path.c_str(), "rb");
+    CHECK(from);
+    uint32 x;
+    uint32 y = 1;
+    while (std::fscanf(from, "%u", &x) == 1) {
+      CHECK(x == y * y);
+      y++;
+    }
+    std::fclose(from);
+    stop();
+  }
+  int32 file_id_to_check_ = 0;
+};
+
+class LoginTestActor : public Actor {
+ public:
+  explicit LoginTestActor(Status *status) : status_(status) {
+    *status_ = Status::OK();
+  }
+
+ private:
+  Status *status_;
+  ActorOwn<TestClient> alice_;
+  ActorOwn<TestClient> bob_;
+
+  string alice_phone_ = "9996636437";
+  string bob_phone_ = "9996636438";
+  string alice_username_ = "alice_" + alice_phone_;
+  string bob_username_ = "bob_" + bob_phone_;
+
+  string stage_name_;
+
+  void begin_stage(string stage_name, double timeout) {
+    LOG(WARNING) << "Begin stage '" << stage_name << "'";
+    stage_name_ = std::move(stage_name);
+    set_timeout_in(timeout);
+  }
+
+  void start_up() override {
+    begin_stage("Logging in", 160);
+    alice_ = create_actor<TestClient>("AliceClient", "alice");
+    bob_ = create_actor<TestClient>("BobClient", "bob");
+
+    send_closure(alice_, &TestClient::add_listener,
+                 std::make_unique<DoAuthentication>(
+                     "alice", alice_phone_, "33333",
+                     PromiseCreator::event(self_closure(this, &LoginTestActor::start_up_fence_dec))));
+
+    send_closure(bob_, &TestClient::add_listener,
+                 std::make_unique<DoAuthentication>(
+                     "bob", bob_phone_, "33333",
+                     PromiseCreator::event(self_closure(this, &LoginTestActor::start_up_fence_dec))));
+  }
+
+  int start_up_fence_ = 3;
+  void start_up_fence_dec() {
+    --start_up_fence_;
+    if (start_up_fence_ == 0) {
+      init();
+    } else if (start_up_fence_ == 1) {
+      return init();
+      class WaitActor : public Actor {
+       public:
+        WaitActor(double timeout, Promise<> promise) : timeout_(timeout), promise_(std::move(promise)) {
+        }
+        void start_up() override {
+          set_timeout_in(timeout_);
+        }
+        void timeout_expired() override {
+          stop();
+        }
+
+       private:
+        double timeout_;
+        Promise<> promise_;
+      };
+      create_actor<WaitActor>("WaitActor", 2,
+                              PromiseCreator::event(self_closure(this, &LoginTestActor::start_up_fence_dec)))
+          .release();
+    }
+  }
+
+  void init() {
+    send_closure(alice_, &TestClient::add_listener,
+                 std::make_unique<SetUsername>(
+                     alice_username_, PromiseCreator::event(self_closure(this, &LoginTestActor::init_fence_dec))));
+    send_closure(bob_, &TestClient::add_listener,
+                 std::make_unique<SetUsername>(
+                     bob_username_, PromiseCreator::event(self_closure(this, &LoginTestActor::init_fence_dec))));
+  }
+
+  int init_fence_ = 2;
+  void init_fence_dec() {
+    if (--init_fence_ == 0) {
+      test_a();
+    }
+  }
+
+  int32 test_a_fence_ = 2;
+  void test_a_fence() {
+    if (--test_a_fence_ == 0) {
+      test_b();
+    }
+  }
+
+  void test_a() {
+    begin_stage("Ready to create chats", 80);
+    string alice_tag = PSTRING() << format::as_hex(Random::secure_int64());
+    string bob_tag = PSTRING() << format::as_hex(Random::secure_int64());
+
+    send_closure(bob_, &TestClient::add_listener,
+                 std::make_unique<CheckTestA>(
+                     alice_tag, PromiseCreator::event(self_closure(this, &LoginTestActor::test_a_fence))));
+    send_closure(alice_, &TestClient::add_listener,
+                 std::make_unique<CheckTestA>(
+                     bob_tag, PromiseCreator::event(self_closure(this, &LoginTestActor::test_a_fence))));
+
+    send_closure(alice_, &TestClient::add_listener, std::make_unique<TestA>(alice_tag, bob_username_));
+    send_closure(bob_, &TestClient::add_listener, std::make_unique<TestA>(bob_tag, alice_username_));
+    // send_closure(alice_, &TestClient::add_listener, std::make_unique<TestChat>(bob_username_));
+  }
+
+  void timeout_expired() override {
+    LOG(FATAL) << "Timeout expired in stage '" << stage_name_ << "'";
+  }
+
+  int32 test_b_fence_ = 1;
+  void test_b_fence() {
+    if (--test_b_fence_ == 0) {
+      test_c();
+    }
+  }
+
+  int32 test_c_fence_ = 1;
+  void test_c_fence() {
+    if (--test_c_fence_ == 0) {
+      finish();
+    }
+  }
+
+  void test_b() {
+    begin_stage("Create secret chat", 40);
+    string tag = PSTRING() << format::as_hex(Random::secure_int64());
+
+    send_closure(
+        bob_, &TestClient::add_listener,
+        std::make_unique<CheckTestA>(tag, PromiseCreator::event(self_closure(this, &LoginTestActor::test_b_fence))));
+    send_closure(alice_, &TestClient::add_listener, std::make_unique<TestSecretChat>(tag, bob_username_));
+  }
+
+  void test_c() {
+    begin_stage("Send generated file", 240);
+    string tag = PSTRING() << format::as_hex(Random::secure_int64());
+
+    send_closure(bob_, &TestClient::add_listener,
+                 std::make_unique<CheckTestC>(
+                     alice_username_, tag, PromiseCreator::event(self_closure(this, &LoginTestActor::test_c_fence))));
+    send_closure(alice_, &TestClient::add_listener, std::make_unique<TestFileGenerated>(tag, bob_username_));
+  }
+
+  int32 finish_fence_ = 2;
+  void finish_fence() {
+    finish_fence_--;
+    if (finish_fence_ == 0) {
+      Scheduler::instance()->finish();
+      stop();
+    }
+  }
+  void finish() {
+    send_closure(alice_, &TestClient::close, PromiseCreator::event(self_closure(this, &LoginTestActor::finish_fence)));
+    send_closure(bob_, &TestClient::close, PromiseCreator::event(self_closure(this, &LoginTestActor::finish_fence)));
+  }
+};
+
+class Tdclient_login : public td::Test {
+ public:
+  using Test::Test;
+  bool step() final {
+    if (!is_inited_) {
+      SET_VERBOSITY_LEVEL(VERBOSITY_NAME(DEBUG) + 2);
+      sched_.init(4);
+      sched_.create_actor_unsafe<LoginTestActor>(0, "LoginTestActor", &result_).release();
+      sched_.start();
+      is_inited_ = true;
+    }
+
+    bool ret = sched_.run_main(10);
+    if (ret) {
+      return true;
+    }
+    sched_.finish();
+    if (result_.is_error()) {
+      LOG(ERROR) << result_;
+    }
+    ASSERT_TRUE(result_.is_ok());
+    return false;
+  }
+
+ private:
+  bool is_inited_ = false;
+  ConcurrentScheduler sched_;
+  Status result_;
+};
+Tdclient_login Tdclient_login("Tdclient_login");
+};  // namespace td
diff --git a/libs/tdlib/td/test/tests_runner.cpp b/libs/tdlib/td/test/tests_runner.cpp
new file mode 100644
index 0000000000..0edb186f0a
--- /dev/null
+++ b/libs/tdlib/td/test/tests_runner.cpp
@@ -0,0 +1,18 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "test/tests_runner.h"
+
+#include "test/TestsRunner.h"
+
+extern "C" {
+void tests_runner_init(const char *dir) {
+  td::TestsRunner::init(dir);
+}
+void run_all_tests() {
+  td::TestsRunner::run_all_tests();
+}
+}
diff --git a/libs/tdlib/td/test/tests_runner.h b/libs/tdlib/td/test/tests_runner.h
new file mode 100644
index 0000000000..3de566858b
--- /dev/null
+++ b/libs/tdlib/td/test/tests_runner.h
@@ -0,0 +1,18 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void tests_runner_init(const char *dir);
+void run_all_tests();
+
+#ifdef __cplusplus
+}
+#endif